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16 pages, 14657 KiB  
Article
Genome-Wide Identification and Role of the bHLH Gene Family in Dendrocalamus latiflorus Flowering Regulation
by Mei-Yin Zeng, Peng-Kai Zhu, Yu Tang, Yu-Han Lin, Tian-You He, Jun-Dong Rong, Yu-Shan Zheng and Ling-Yan Chen
Int. J. Mol. Sci. 2024, 25(19), 10837; https://doi.org/10.3390/ijms251910837 - 9 Oct 2024
Viewed by 382
Abstract
The basic helix–loop–helix (bHLH) gene family is a crucial regulator in plants, orchestrating various developmental processes, particularly flower formation, and mediating responses to hormonal signals. The molecular mechanism of bamboo flowering regulation remains unresolved, limiting bamboo breeding efforts. In this study, [...] Read more.
The basic helix–loop–helix (bHLH) gene family is a crucial regulator in plants, orchestrating various developmental processes, particularly flower formation, and mediating responses to hormonal signals. The molecular mechanism of bamboo flowering regulation remains unresolved, limiting bamboo breeding efforts. In this study, we identified 309 bHLH genes and divided them into 23 subfamilies. Structural analysis revealed that proteins in specific DlbHLH subfamilies are highly conserved. Collinearity analysis indicates that the amplification of the DlbHLH gene family primarily occurs through segmental duplications. The structural diversity of these duplicated genes may account for their functional variability. Many DlbHLHs are expressed during flower development, indicating the bHLH gene’s significant role in this process. In the promoter region of DlbHLHs, different homeopathic elements involved in light response and hormone response co-exist, indicating that DlbHLHs are related to the regulation of the flower development of D. latiflorus. Full article
(This article belongs to the Special Issue Transcription Factors in Plant Gene Expression Regulation)
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Figure 1

Figure 1
<p>Maximum likelihood (ML) phylogenetic tree of bHLH proteins from <span class="html-italic">D. latiflorus</span>, <span class="html-italic">A. thaliana</span>, <span class="html-italic">O. sativa</span>, and <span class="html-italic">T. aestivum</span>. Sub is short for subfamily.</p>
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<p>The phylogenetic relationship, conserved motifs, and gene structure of <span class="html-italic">DlbHLHs</span>. (<b>A</b>): The maximum likelihood (ML) phylogenetic tree of DlbHLH protein was constructed using the full-length sequence of 1000 bootstrap repeats; (<b>B</b>): Distribution of conserved motifs of DlbHLH protein. A total of 20 patterns were predicted, and the scale bar represented 200 aa. (<b>C</b>): bHLH domain distribution of <span class="html-italic">DlbHLHs</span>; (<b>D</b>): Genetic structure of <span class="html-italic">DlbHLHs</span>, including coding sequences (yellow rectangle) and untranslated regions (UTRs, green rectangle). The scale bar represents 10,000 bp.</p>
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<p>Chromosomal location and collinearity analysis of <span class="html-italic">DlbHLH</span> family genes. The letters A–C represent the subgenomic distribution of <span class="html-italic">DlbHLHs</span>. Blue-purple for subgenome A, green for subgenome B, and blue for subgenome C. Chromosomes are represented by light blue boxes. Segmental duplication genes are connected with blue lines. Tandem duplication genes are connected with red lines.</p>
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<p><span class="html-italic">bHLH</span> gene collinearity analysis of <span class="html-italic">D. latiflorus</span> and 4 representative plants.</p>
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<p>The number of CREs on putative promoters of <span class="html-italic">DlbHLHs</span>.</p>
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<p>Hierarchical clustering of <span class="html-italic">DlbHLH</span> expression at different flowering stages. The heatmap was drawn based on the log2 (TPM+1) values. TPM: transcripts per million mapped reads. The size and color scales represent expression levels from low to high. The eight genes highlighted in red are selected for qRT-PCR.</p>
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<p><span class="html-italic">D. latiflorus</span> flower can be divided into four stages: young bud stage (<b>F1</b>), flowering mid-term stage (<b>F2</b>), full-bloom stage (<b>F3</b>), and fading stage (<b>F4</b>).</p>
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<p>Relative expression patterns of eight selected <span class="html-italic">DlbHLH</span> genes in four flower developmental stages. Asterisks indicate significant differences in qRT-PCR relative expression level compared with those of the early stage of young bud stage (F1). (* <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01, **** <span class="html-italic">p</span> &lt; 0.0001).</p>
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21 pages, 4545 KiB  
Article
SkipResNet: Crop and Weed Recognition Based on the Improved ResNet
by Wenyi Hu, Tian Chen, Chunjie Lan, Shan Liu and Lirong Yin
Land 2024, 13(10), 1585; https://doi.org/10.3390/land13101585 - 29 Sep 2024
Viewed by 351
Abstract
Weeds have a detrimental effect on crop yield. However, the prevailing chemical weed control methods cause pollution of the ecosystem and land. Therefore, it has become a trend to reduce dependence on herbicides; realize a sustainable, intelligent weed control method; and protect the [...] Read more.
Weeds have a detrimental effect on crop yield. However, the prevailing chemical weed control methods cause pollution of the ecosystem and land. Therefore, it has become a trend to reduce dependence on herbicides; realize a sustainable, intelligent weed control method; and protect the land. In order to realize intelligent weeding, efficient and accurate crop and weed recognition is necessary. Convolutional neural networks (CNNs) are widely applied for weed and crop recognition due to their high speed and efficiency. In this paper, a multi-path input skip-residual network (SkipResNet) was put forward to upgrade the classification function of weeds and crops. It improved the residual block in the ResNet model and combined three different path selection algorithms. Experiments showed that on the plant seedling dataset, our proposed network achieved an accuracy of 95.07%, which is 0.73%, 0.37%, and 4.75% better than that of ResNet18, VGG19, and MobileNetV2, respectively. The validation results on the weed–corn dataset also showed that the algorithm can provide more accurate identification of weeds and crops, thereby reducing land contamination during the weeding process. In addition, the algorithm is generalizable and can be used in image classification in agriculture and other fields. Full article
(This article belongs to the Special Issue GeoAI for Land Use Observations, Analysis and Forecasting)
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<p>General description of the methodology for weed classification.</p>
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<p>Structure of a residual block: x is the data input to layer1, F(x) is the output after the data are computed by layer1 and layer2, and there is a skip connection between x and F(x) such that the output of the residual block becomes x + F(x).</p>
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<p>Improvement of residual blocks: x is the data input of ayer1 (the output of the layer before layer 1 in the network), x0 are the original input data, and F(x) is the output after the computation of layer1 and layer2. After deriving F(x), x0 is re-inputted so that the output of the residual block is changed to x0 + F(x).</p>
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<p>The framework of ResNet, SkipResNet, and SkipNet. (<b>a</b>) The 18-layer ResNet, which is equivalent to the 18-layer SkipResNet when k = 1; (<b>b</b>) the 18-layer SkipResNet, which shows the first input in the middle layer of the path (k = 2); (<b>c</b>) the 18-layer SkipResNet, with the figure showing the second input path at the middle layer (k = 3); and (<b>d</b>) evaluation of the 18-layer SkipNet for the CIFAR-10 dataset, with an input image resolution of 32 × 32. Here, k is the input path labeling.</p>
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<p>The framework of ResNet, SkipResNet, and SkipNet. (<b>a</b>) The 18-layer ResNet, which is equivalent to the 18-layer SkipResNet when k = 1; (<b>b</b>) the 18-layer SkipResNet, which shows the first input in the middle layer of the path (k = 2); (<b>c</b>) the 18-layer SkipResNet, with the figure showing the second input path at the middle layer (k = 3); and (<b>d</b>) evaluation of the 18-layer SkipNet for the CIFAR-10 dataset, with an input image resolution of 32 × 32. Here, k is the input path labeling.</p>
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<p>Example images of the plant seedling dataset [<a href="#B29-land-13-01585" class="html-bibr">29</a>]. The labels in this figure correspond to the labels in <a href="#land-13-01585-t002" class="html-table">Table 2</a>. (<b>a</b>) Black-grass, (<b>b</b>) charlock, (<b>c</b>) cleavers, (<b>d</b>) common chickweed, (<b>e</b>) common wheat, (<b>f</b>) fat hen, (<b>g</b>) loose silky-bent, (<b>h</b>) maize, (<b>i</b>) scentless mayweed, (<b>j</b>) shepherd’s purse, (<b>k</b>) small-flowered cranesbill, and (<b>l</b>) sugar beet.</p>
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<p>Weed–corn dataset [<a href="#B14-land-13-01585" class="html-bibr">14</a>]: (<b>a</b>) bluegrass, (<b>b</b>) chenopodium album, (<b>c</b>) cirsium setosum, (<b>d</b>) sedge, and (<b>e</b>) corn.</p>
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<p>CIFAR-10 dataset [<a href="#B30-land-13-01585" class="html-bibr">30</a>].</p>
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<p>Confusion matrices of SkipResNet18, ResNet18, VGG19, and MobileNetV2 on a test set of 12 plant seedlings: (<b>a</b>) SkipResNet18; (<b>b</b>) ResNet18; (<b>c</b>) VGG19; (<b>d</b>) MobileNetV2. The 12 species considered were (1) black-grass, (2) charlock, (3) cleavers, (4) common chickweed, (5) common wheat, (6) fat hen, (7) loose silky-bent, (8) maize, (9) scentless mayweed, (10) shepherd’s purse, (11) small-flowered cranesbill, and (12) sugar beet.</p>
Full article ">Figure 8 Cont.
<p>Confusion matrices of SkipResNet18, ResNet18, VGG19, and MobileNetV2 on a test set of 12 plant seedlings: (<b>a</b>) SkipResNet18; (<b>b</b>) ResNet18; (<b>c</b>) VGG19; (<b>d</b>) MobileNetV2. The 12 species considered were (1) black-grass, (2) charlock, (3) cleavers, (4) common chickweed, (5) common wheat, (6) fat hen, (7) loose silky-bent, (8) maize, (9) scentless mayweed, (10) shepherd’s purse, (11) small-flowered cranesbill, and (12) sugar beet.</p>
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<p>Precision–recall plots for (<b>a</b>) SkipResNet18, (<b>b</b>) ResNet18, (<b>c</b>) VGG19, and (<b>d</b>) MobileNetV2.</p>
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<p>Precision–recall plots for (<b>a</b>) SkipResNet18, (<b>b</b>) ResNet18, (<b>c</b>) VGG19, and (<b>d</b>) MobileNetV2.</p>
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<p>Confusion matrices for SkipResNet18 and ResNet18 on four weed and corn test sets. (<b>a</b>) SkipResNet18 and (<b>b</b>) ResNet18. The 5 species considered were (1) bluegrass, (2) chenopodium album, (3) cirsium setosum, (4) corn, and (5) sedge.</p>
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<p>Accuracy of SkipNet18, ResNet18, VGG19, and ResNet34 models on the CIFAR-10 dataset.</p>
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22 pages, 5943 KiB  
Article
Dynamic Analysis and Risk Assessment of Vegetation Net Primary Productivity in Xinjiang, China
by Wenjie Zhang, Xiang Zhao, Hao Li, Yutong Fang, Wenxi Shi, Siqing Zhao and Yinkun Guo
Remote Sens. 2024, 16(19), 3604; https://doi.org/10.3390/rs16193604 - 27 Sep 2024
Viewed by 555
Abstract
Vegetation net primary productivity (NPP) is a key indicator for assessing vegetation dynamics and carbon cycle balance. Xinjiang is located in an arid and ecologically fragile region in northwest China, but the current understanding of vegetation dynamics in the region is still limited. [...] Read more.
Vegetation net primary productivity (NPP) is a key indicator for assessing vegetation dynamics and carbon cycle balance. Xinjiang is located in an arid and ecologically fragile region in northwest China, but the current understanding of vegetation dynamics in the region is still limited. This study aims to analyze Xinjiang’s NPP spatial and temporal trends, using random forest regression to quantify the extent to which climate change and human activities affect vegetation productivity. CMIP6 (Coupled Model Intercomparison Project Phase 6) climate scenario data help assess vegetation restoration potential and future risks. Our findings indicate that (1) Xinjiang’s NPP exhibits a significant increasing trend from 2001 to 2020, with three-quarters of the region experiencing an increase, 2.64% of the area showing significant decrease (p < 0.05), and the Ili River Basin showing a nonsignificant decreasing trend; (2) precipitation and radiation are major drivers of NPP variations, with contribution ratios of 35.13% and 30.17%, respectively; (3) noteworthy restoration potential exists on the Tian Shan northern slope and the Irtysh River Basin, where average restoration potentials surpass 80% relative to 2020, while the Ili River Basin has the highest future risk. This study explores the factors influencing the current vegetation dynamics in Xinjiang, aiming to provide references for vegetation restoration and future risk mitigation, thereby promoting sustainable ecological development in Xinjiang. Full article
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<p>Location of the study area in China and spatial distribution of land cover types in study area in 2020. XJ, IR, NTM, IlR, TB, and TR denote Xinjiang, the Irtysh River, north slope of the Tianshan Mountains, Ili River, Turpan Basin, and Tarim River, respectively.</p>
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<p>Annual difference and mean values of vegetation NPP in Xinjiang from 2001 to 2020. (<b>a</b>–<b>d</b>) represent the difference between the four study periods of 2001–2005, 2006–2010, 2011–2015, and 2016–2020, respectively. The units of NPP are all gC/m<sup>2</sup>∙a. (<b>e</b>) Box plots of NPP averages for the whole of Xinjiang and the five major regions. XJ, IR, NTM, IlR, TB, and TR denote the Xinjiang, Irtysh River, north slope of the Tianshan Mountains, Ili River, Turpan Basin, and Tarim River, respectively.</p>
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<p>Spatial and temporal trends of the NPP from 2001 to 2020 in Xinjiang. (<b>a</b>) Spatial distribution of the Sen slope of NPP change in Xinjiang from 2001 to 2020; (<b>b</b>) The spatial distribution of the annual mean NPP trend in Xinjiang from 2001 to 2020. (<b>c</b>) The stack bar of the trend grouped by types of significance in major regions and the whole of Xinjiang. The fold line graph of the NPP mean trend in five areas (<b>d</b>–<b>h</b>) and the whole of Xinjiang (<b>i</b>) from 2001 to 2020. NS, NNS, NC, PS, and PNS denote negative significant, negative non-significant, nonsignificant change, positive significant, and positive nonsignificant, respectively; XJ, IR, NTM, IlR, TB, and TR denote the Xinjiang, Irtysh River, north slope of the Tianshan Mountains, Ili River, Turpan Basin, and Tarim River, respectively.</p>
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<p>Twenty-year averages (<b>a</b>–<b>e</b>) and annual mean change rates (<b>f</b>–<b>j</b>) of precipitation, temperature, downward shortwave radiation, wind, and livestock density in Xinjiang. PR, TEM, SRAD, Wind, and LD denote the precipitation, temperature, downward shortwave radiation, wind speed, and livestock density, respectively.</p>
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<p>The contribution of each factor to NPP given by random forest. (<b>a</b>) is the result of the residual contribution; (<b>b</b>) is the result of the combined contribution when the average and residual contributions are superimposed. (<b>c</b>) shows the average of the comprehensive contribution of each factor for each pixel in the five regions and the whole of Xinjiang. Each pixel in (<b>a</b>,<b>b</b>) shows the highest contributing factor of the six factors: precipitation, temperature, sinking shortwave radiation, wind speed, livestock density, and CO<sub>2</sub>. PR, TEM, SRAD, Wind, LD, and CO<sub>2</sub> denote the precipitation, temperature, downward shortwave radiation, wind speed, livestock density, and CO<sub>2</sub>, respectively; XJ, IR, NTM, IlR, TB, and TR denote the Xinjiang, Irtysh River, north slope of the Tianshan Mountains, Ili River, Turpan Basin, and Tarim River, respectively.</p>
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<p>Spatial distribution and statistics of the VRPRI in Xinjiang. (<b>a</b>) Spatial distribution of the VRPRI; (<b>b</b>) box plots of the ratio of the VRPRI across the whole of Xinjiang and the five regions. XJ, IR, NTM, IlR, TB, and TR denote the Xinjiang, Irtysh River, north slope of the Tianshan Mountains, Ili River, Turpan Basin, and Tarim River, respectively.</p>
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<p>Risk of change in NPP in Xinjiang from 2025 to 2050. (<b>a</b>–<b>c</b>) Spatial distribution of change risk under scenarios SSP1-2.6, SSP2-4.5, and SSP5-8.5; (<b>d</b>–<b>f</b>) proportion of each risk class in Xinjiang and the five regions. XJ, IR, NTM, IlR, TB, and TR denote the Xinjiang, Irtysh River, north slope of the Tianshan Mountains, Ili River, Turpan Basin, and Tarim River, respectively.</p>
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22 pages, 6823 KiB  
Article
A Study on the Heterogeneity of China’s Provincial Economic Growth Contribution to Carbon Emissions
by Ruiqin Tian, Miaojie Xia, Yuqi Zhang, Dengke Xu and Shan Lu
Systems 2024, 12(10), 391; https://doi.org/10.3390/systems12100391 - 26 Sep 2024
Viewed by 652
Abstract
Achieving “dual carbon” targets by containing carbon emissions while sustaining economic growth is challenging. This study examines the varying carbon dependency levels among China’s 30 provincial-level administrative units, considering spatial correlations in emissions. Using a semi-parametric varying coefficient spatial autoregressive panel model on [...] Read more.
Achieving “dual carbon” targets by containing carbon emissions while sustaining economic growth is challenging. This study examines the varying carbon dependency levels among China’s 30 provincial-level administrative units, considering spatial correlations in emissions. Using a semi-parametric varying coefficient spatial autoregressive panel model on 2004–2019 panel data, this study shows the following: (i) The relationship between economic growth and carbon emissions forms an “S”-shaped curve, with the contribution decreasing as tertiary industry grows, defining three stages of carbon dependency. (ii) There is significant heterogeneity in carbon dependency across provinces, with some advancing to “weak dependency” or an “economic carbon peak” due to advantages and policies. (iii) Dependency levels shift over time, with “weak dependency” being the predominant stage, though transitions occur. (iv) A positive spatial spillover effect in emissions was noted. This study recommends tailored policies for each provincial-level administrative unit based on their carbon dependency and development stage. Full article
(This article belongs to the Section Systems Practice in Social Science)
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<p>Log per capita GDP against log carbon emissions scatter plot.</p>
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<p>Carbon emission distribution map for selected years in China.</p>
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<p>Estimation of varying coefficient <math display="inline"><semantics> <mrow> <mi>g</mi> <mo>(</mo> <mo>·</mo> <mo>)</mo> </mrow> </semantics></math> (blue solid line) and zero line (green dashed line).</p>
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<p>Per capita GDP coefficient distribution map of key years in China.</p>
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<p>Stage map of key years in China.</p>
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17 pages, 4093 KiB  
Article
Genetic Diversity of Tulipa alberti and T. greigii Populations from Kazakhstan Based on Application of Expressed Sequence Tag Simple Sequence Repeat Markers
by Moldir Yermagambetova, Shyryn Almerekova, Anna Ivashchenko, Yerlan Turuspekov and Saule Abugalieva
Plants 2024, 13(18), 2667; https://doi.org/10.3390/plants13182667 - 23 Sep 2024
Viewed by 480
Abstract
The genus Tulipa L., renowned for its ornamental and ecological significance, encompasses a diversity of species primarily concentrated in the Tian Shan and Pamir-Alay Mountain ranges. With its varied landscapes, Kazakhstan harbors 42 Tulipa species, including the endangered Tulipa alberti Regel and Tulipa [...] Read more.
The genus Tulipa L., renowned for its ornamental and ecological significance, encompasses a diversity of species primarily concentrated in the Tian Shan and Pamir-Alay Mountain ranges. With its varied landscapes, Kazakhstan harbors 42 Tulipa species, including the endangered Tulipa alberti Regel and Tulipa greigii Regel, which are critical for biodiversity yet face significant threats from human activities. This study aimed to assess these two species’ genetic diversity and population structure using 15 expressed sequence tag simple sequence repeat (EST-SSR) markers. Leaf samples from 423 individuals across 23 natural populations, including 11 populations of T. alberti and 12 populations of T. greigii, were collected and genetically characterized using EST-SSR markers. The results revealed relatively high levels of genetic variation in T. greigii compared to T. alberti. The average number of alleles per locus was 1.9 for T. alberti and 2.8 for T. greigii. AMOVA indicated substantial genetic variation within populations (75% for T. alberti and 77% for T. greigii). The Bayesian analysis of the population structure of the two species indicated an optimal value of K = 3 for both species, splitting all sampled populations into three distinct genetic clusters. Populations with the highest level of genetic diversity were identified in both species. The results underscore the importance of conserving the genetic diversity of Tulipa populations, which can help develop strategies for their preservation in stressed ecological conditions. Full article
(This article belongs to the Section Plant Genetics, Genomics and Biotechnology)
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<p>Principal coordinate analysis (PCoA) plots for <span class="html-italic">Tulipa alberti</span> populations (<b>A</b>); <span class="html-italic">Tulipa greigii</span> populations (<b>B</b>); and for <span class="html-italic">Tulia alberti</span> and <span class="html-italic">Tulipa greigii</span> populations (<b>C</b>). T.A.—<span class="html-italic">Tulipa alberti</span>; T.Gr.—<span class="html-italic">Tulipa greigii</span>.</p>
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<p>Unweighted pair group method with arithmetic mean (UPGMA) tree constructed from polymorphic EST-SSR loci of <span class="html-italic">Tulipa alberti and Tulipa greigii</span> populations. T.A.—<span class="html-italic">Tulipa alberti</span>; T.Gr.—<span class="html-italic">Tulipa greigii</span>.</p>
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<p>Genetic structure of <span class="html-italic">Tulipa alberti</span> (T.A.) populations. Distribution of <span class="html-italic">Tulipa alberti</span> populations (<b>A</b>); UPGMA tree of <span class="html-italic">Tulipa alberti</span> populations (<b>B</b>); STRUCTURE analysis graphic with the Evanno method showing optimal K = 3 (<b>C</b>); and Bayesian inference clustering of 207 individuals from 11 <span class="html-italic">Tulipa alberti</span> populations (<b>D</b>).</p>
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<p>Genetic structure of <span class="html-italic">Tulipa greigii</span> (T.Gr.) populations. Distribution of <span class="html-italic">T. greigii</span> populations (<b>A</b>); UPGMA tree of <span class="html-italic">T. greigii</span> populations (<b>B</b>); STRUCTURE analysis graphic with the Evanno method showing optimal K = 3 (<b>C</b>); and Bayesian inference clustering of 216 individuals from 12 <span class="html-italic">T. greigii</span> populations (<b>D</b>).</p>
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<p><span class="html-italic">Tulipa alberti</span> (<b>A</b>) and <span class="html-italic">Tulipa greigii</span> (<b>B</b>) species in nature. Photos were taken by Oleg Belyalov.</p>
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<p>Location of sampled <span class="html-italic">Tulipa alberti</span> (<b>A</b>) and <span class="html-italic">Tulipa greigii</span> (<b>B</b>) populations in Kazakhstan. Pop—population; numeration according to <a href="#plants-13-02667-t001" class="html-table">Table 1</a>. T.A.—<span class="html-italic">Tulipa alberti</span>; T.Gr.—<span class="html-italic">Tulipa greigii</span>.</p>
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17 pages, 14394 KiB  
Article
Quaternary Deformation along the Gobi–Tian Shan Fault in the Easternmost Tian Shan (Harlik Mountain), Central Asia
by Tianyi Shen, Yan Ding, Guocan Wang, Dehai Zhang and Zihao Zhao
Remote Sens. 2024, 16(17), 3343; https://doi.org/10.3390/rs16173343 - 9 Sep 2024
Viewed by 556
Abstract
The Tian Shan is a typical active intracontinental orogenic belt that is driven by the ongoing indentation of India into Eurasia. However, the geological features of Quaternary deformation, especially in the easternmost sector near Harlik Mountain, remain elusive. Field observations, topographic analysis, and [...] Read more.
The Tian Shan is a typical active intracontinental orogenic belt that is driven by the ongoing indentation of India into Eurasia. However, the geological features of Quaternary deformation, especially in the easternmost sector near Harlik Mountain, remain elusive. Field observations, topographic analysis, and Electron Spin Resonance (ESR) dating were employed to comprehensively assess the deformation features and evaluate the deformation pattern for this region during the Quaternary period. The results disclose evidence of deformation in the northern and southern foreland basins of Harlik Mountain. In the Barkol Basin to the north, crustal shortening results in the formation of surface scarps and folds, indicating north-directed thrusting, with a shortening rate of ~0.15 mm/yr. In the Hami Basin, the north-directed thrust elevates the granites, which offset the alluvial fans, with a shortening rate of ~0.18 mm/yr. Together with the shortening along the boundary fault, the aggregated north–south shortening rate is approximately 0.69 mm/yr in the easternmost Tian Shan, corresponding with the differential motion rate between the north and south Harlik Mountain revealed by the GPS velocity. These findings imply that, distal to the collision zone, tectonic strain in the eastern Tian Shan is primarily accommodated through the reactivation of pre-existing strike–slip faults, with crustal shortening concentrated at the overlapping position of parallel northeast-trending left-lateral strike–slip faults. Full article
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<p>Active faults and GPS-derived horizontal velocity field in the Tian Shan region. The map showcases the distribution of active fault lines according to Cunningham et al. [<a href="#B14-remotesensing-16-03343" class="html-bibr">14</a>], Yin [<a href="#B6-remotesensing-16-03343" class="html-bibr">6</a>], and Wu et al. [<a href="#B15-remotesensing-16-03343" class="html-bibr">15</a>], overlaid with GPS horizontal velocity field data from Zhao et al. [<a href="#B16-remotesensing-16-03343" class="html-bibr">16</a>]. The arrows indicate GPS velocities and error ellipses represent 70% confidence. Key structural features include the Gobi–Tian Shan Fault (GTF), Jianquanzi–Luobaoquan Faults (JLF), Xingxingxia Fault (XXF), Kuruk Tagh Fault (KTF), Nikolaev Line (NL, also known as the Nalati Fault), and Huoyanshan thrust belt (HYS).</p>
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<p>Active faults and main geological rock distribution around Harlik Mountain. This topographical map illustrates the active faults in the vicinity of Harlik Mountain, with fault lines adapted from Cunningham et al. [<a href="#B14-remotesensing-16-03343" class="html-bibr">14</a>] and Wu et al. [<a href="#B15-remotesensing-16-03343" class="html-bibr">15</a>]. It also presents shortening and slip rates from previous studies by Xu [<a href="#B38-remotesensing-16-03343" class="html-bibr">38</a>] and Ren [<a href="#B39-remotesensing-16-03343" class="html-bibr">39</a>], alongside GPS velocity data from Wang and Shen [<a href="#B40-remotesensing-16-03343" class="html-bibr">40</a>]. Insets blue boxes highlight detailed areas of specific interest, shown in subsequent figures. The black box illustrates the area of the tectonic model.</p>
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<p>Deformation features in the Barkol Basin. (<b>A</b>) Satellite image from Google Earth delineating the fault trace (red lines) within the basin. (<b>B</b>) Oblique aerial view from Google Earth showing the fault scarps (red lines), with the topographic profile detailed in (<b>D</b>). (<b>C</b>) Depiction of fold geometry in the Barkol Basin, with locations for the geological cross-section (<b>E</b>) and two UAV-derived topographic profiles (<b>F</b>) indicated. The <sup>10</sup>Be exposure age of exposed quartz boulder, based on Xu [<a href="#B38-remotesensing-16-03343" class="html-bibr">38</a>] and Ren [<a href="#B39-remotesensing-16-03343" class="html-bibr">39</a>], is noted. (<b>D</b>) dGPS-measured topographic profile across the fault, showing an elevation difference of ~14.12 m. (<b>E</b>) Field photo (<b>top</b>) and geological cross-section (<b>bottom</b>) of the fold at its eastern extremity, highlighting the folded sedimentary layers with ESR-dated ages of 838 and 895 ka. (<b>F</b>) UAV-derived topographic profiles of the fold, including the calculated area of horizontal crustal shortening (<b>A</b>), which provided quantitative insights into the geological deformation.</p>
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<p>Surface deformation features at the southern Harlik Mountain. (<b>A</b>) Gaofen-7 satellite imagery provides an overview of the main active faults near the southern side of Harlik Mountain, with the <sup>10</sup>Be exposure age of an exposed quartz boulder from Ren [<a href="#B39-remotesensing-16-03343" class="html-bibr">39</a>] annotated. (<b>B</b>) A detailed view illustrates the juxtaposition of granite against Quaternary alluvial fans. The boxes of a, b and c show the location of UAV surveys. Red lines are the faults. (<b>C</b>) A photograph displaying the tilted sedimentary layers of the alluvial fan overlying the granite, with the location of the ESR sample and its age marked. (<b>D</b>) A drone-captured image of the western part of the southern branch fault. The triangles illustrate the topographic boundary. (<b>E</b>) The site and age of the ESR-dated alluvial fan sediment north of the southern branch fault.</p>
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<p>Vertical offset analysis of branch faults near Harlik Mountain. (<b>A</b>) Topographic profiles displaying vertical offsets across the branch faults, with elevations obtained from Gaofen-7 satellite data. (<b>B</b>) DEMs from UAV surveys illustrating the landscape and fault lines, with profiles marked as a, b, and c. (<b>C</b>) Detailed topographic profiles from UAV-derived DEMs showcasing the vertical offsets along the southern fault, with annotations of displacement measurements and the ESR age of sediment displacement.</p>
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<p>Crustal deformation rates in the easternmost Tian Shan. This three-dimensional structural model integrates fault interpretations from our current field observations with data from previous research [<a href="#B39-remotesensing-16-03343" class="html-bibr">39</a>,<a href="#B44-remotesensing-16-03343" class="html-bibr">44</a>]. It displays the various rates of crustal shortening and horizontal slip identified in this study (indicated in regular font) alongside those from prior studies (shown in italics). The black arrows indicate the crustal shortening direction according to the GPS velocity.</p>
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14 pages, 1831 KiB  
Article
Insights into the Synergistic Effect and Inhibition Mechanism of Composite Conditioner on Sulfur-Containing Gases during Sewage Sludge Pyrolysis
by Shan Cheng, Lianghui Chen, Shaoshuo Wang, Kehui Yao and Hong Tian
Molecules 2024, 29(17), 4110; https://doi.org/10.3390/molecules29174110 - 29 Aug 2024
Viewed by 408
Abstract
Sewage sludge odorous gas release is a key barrier to resource utilization, and conditioners can mitigate the release of sulfur-containing gases. The gas release characteristics and sulfur compound distribution in pyrolysis products under both single and composite conditioning strategies of CaO, Fe2 [...] Read more.
Sewage sludge odorous gas release is a key barrier to resource utilization, and conditioners can mitigate the release of sulfur-containing gases. The gas release characteristics and sulfur compound distribution in pyrolysis products under both single and composite conditioning strategies of CaO, Fe2O3, and FeCl3 were investigated. This study focused on the inhibition mechanisms of these conditioners on sulfur-containing gas emissions and compared the theoretical and experimental sulfur content in the products to evaluate the potential synergistic effects of the composite conditioners. The findings indicated that at 650 °C, CaO, Fe2O3, and FeCl3 inhibited H2S release by 35.8%, 23.2%, and 9.1%, respectively. Notably, the composite of CaO with FeCl3 at temperatures ranging from 350 to 450 °C and the combination of Fe2O3 with FeCl3 at 650 °C were found to exert synergistic suppression on H2S emissions. The strongly alkaline CaO inhibited the metathesis reaction between HCl, a decomposition product of FeCl3, and the sulfur-containing compounds within the sewage sludge, thereby exerting a synergistic suppression on the emission of H2S. Conversely, at temperatures exceeding 550 °C, the formation of Ca-Fe compounds, such as FeCa2O4, appeared to diminish the sulfur-fixing capacity of the conditioners, resulting in increased H2S emissions. For instance, the combination of CaO and FeCl3 at 450 °C was found to synergistically reduce H2S emissions by 56.3%, while the combination of CaO and Fe2O3 at 650 °C synergistically enhances the release of H2S by 23.6%. The insights gained from this study are instrumental in optimizing the pyrolysis of sewage sludge, aiming to minimize its environmental footprint and enhance the efficiency of resource recovery. Full article
(This article belongs to the Special Issue Renewable Energy, Fuels and Chemicals from Biomass)
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<p>Distribution of sulfur in gaseous products. (Red represents H<sub>2</sub>S, orange represents COS, yellow represents SO<sub>2</sub>, green represents CH<sub>3</sub>SH, and blue represents CS<sub>2</sub>).</p>
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<p>H<sub>2</sub>S release at various pyrolysis temperatures. (Red represent 650 °C, orange represent 550 °C, green represent 450 °C, and blue represent 350 °C).</p>
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<p>The theoretical and experimental release of H<sub>2</sub>S from composite-conditioned sludge: (<b>a</b>) RS-CaO-Fe<sub>2</sub>O<sub>3</sub> (2:1), (<b>b</b>) RS-CaO-Fe<sub>2</sub>O<sub>3</sub> (1:1), (<b>c</b>) RS-CaO-Fe<sub>2</sub>O<sub>3</sub> (1:2), (<b>d</b>) RS-CaO-FeCl<sub>3</sub> (2:1), (<b>e</b>) RS-CaO-FeCl<sub>3</sub> (1:1), (<b>f</b>) RS-CaO-FeCl<sub>3</sub> (1:2), (<b>g</b>) RS-Fe<sub>2</sub>O<sub>3</sub>-FeCl<sub>3</sub> (2:1), (<b>h</b>) RS-Fe<sub>2</sub>O<sub>3</sub>-FeCl<sub>3</sub> (1:1), and (<b>i</b>) RS-Fe<sub>2</sub>O<sub>3</sub>-FeCl<sub>3</sub> (1:2).</p>
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<p>The synergistic effect of composite conditioners in suppressing the release of H<sub>2</sub>S during sludge pyrolysis.</p>
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<p>Distribution of sulfur-containing substances in sludge and pyrolysis char. (<b>a</b>) RS, (<b>b</b>) RS-char, (<b>c</b>) RS-CaO-char, (<b>d</b>) RS-Fe<sub>2</sub>O<sub>3</sub>-char, (<b>e</b>) RS-FeCl<sub>3</sub>-char, and (<b>f</b>) the content of sulfur-containing substances. (S1: inorganic sulfates; S2: sulfones; S3: sulfoxides; S4: aromatic sulfur; S5: aliphatic sulfur; S6: inorganic sulfides).</p>
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<p>Distribution of sulfur-containing products in the pyrolysis char of composite-conditioned sludge. (<b>a</b>) The S 2p spectrum of RS-CaO-Fe<sub>2</sub>O<sub>3</sub> (1:1)-char, (<b>b</b>) the S 2p spectrum of RS-Fe<sub>2</sub>O<sub>3</sub>-FeCl<sub>3</sub> (2:1)-char, (<b>c</b>) the content of sulfur-containing substances of RS-CaO-Fe<sub>2</sub>O<sub>3</sub> (1:1)-char, and (<b>d</b>) the content of sulfur-containing substances of RS-Fe<sub>2</sub>O<sub>3</sub>-FeCl<sub>3</sub> (2:1)-char. (S1: inorganic sulfates; S2: sulfones; S3: sulfoxides; S4: aromatic sulfur; S5: aliphatic sulfur; and S6: inorganic sulfides).</p>
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<p>XRD spectrum of solid-phase products from sludge pyrolysis: (<b>a</b>) RS and singly conditioned sludge; (<b>b</b>) composite-conditioned sludge.</p>
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13 pages, 5172 KiB  
Article
Research on the Support Technology for Deep Large-Section Refuge Chambers in Broken Surrounding Rock in a Roadway
by Wenqing Peng and Shenghua Feng
Appl. Sci. 2024, 14(17), 7527; https://doi.org/10.3390/app14177527 - 26 Aug 2024
Viewed by 367
Abstract
The phenomenon of peripheral rock instability is more common in crushed bedrock roadways, and the fundamental reason for this lies in the significantly different characteristics of its peripheral rock stress field. Taking the newly dug belt inclined shaft of PingDingShan TianAn Coal Co., [...] Read more.
The phenomenon of peripheral rock instability is more common in crushed bedrock roadways, and the fundamental reason for this lies in the significantly different characteristics of its peripheral rock stress field. Taking the newly dug belt inclined shaft of PingDingShan TianAn Coal Co., Ltd. No. 6 Mine as the engineering background, a mechanical model of a broken perimeter rock roadway was established by using classical rock mechanics theory. Stress distribution around the roadway of the broken perimeter rock medium was systematically analyzed, and radial and tangential stress formulas of the broken perimeter rock were deduced. Through the formula calculation, it was deduced that there was a stress drop in the intact surrounding rock outside the disturbed zone, and the radial stress of the intact surrounding rock in its deep part was relatively increased, while the tangential stress was relatively decreased. The existence of crushed surrounding rock increased the minimum principal stress and decreased the maximum principal stress of the unfractured surrounding rock, which proves that a well-maintained disturbed zone can play a lining role. Thus, a “U-shaped steel + inverted arch + bottom arch linkage beam + floor bolt compensation” support program was proposed. This joint support program easily forms a closed support structure, which is more effective in controlling the deformation of tunnel perimeter rock. The support structure can effectively resist the deformation of the surrounding rock and enhance bottom drum resistance. Through numerical simulation, it was concluded that the horizontal displacement of the two gangs was reduced by 70%, and the displacement of the top and bottom plates was reduced by 77% after optimization of the support, which effectively controlled the stability of the broken surrounding rock. Full article
(This article belongs to the Special Issue Advances and Challenges in Rock Mechanics and Rock Engineering)
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<p>Mechanical model of a roadway.</p>
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<p>Mechanical model of “surrounding rock–support’’ in the broken surrounding rock of a roadway.</p>
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<p>Relationship between support force, surrounding rock pressure, and influence radius of broken surrounding rock.</p>
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<p>(<b>a</b>) U-shaped steel bracket; (<b>b</b>) anti-bottom arch interlocking beams; (<b>c</b>) support program (unmarked numbers are measured in mm).</p>
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<p>Numerical analysis model diagram of FLAC3D: (<b>a</b>) numerical analysis model of rock formation; (<b>b</b>) numerical analysis model of support.</p>
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<p>Surrounding rock displacement nephogram: (<b>a</b>) horizontal displacement nephogram before optimization. (<b>b</b>) Horizontal displacement nephogram after optimization. (<b>c</b>) Vertical displacement nephogram before optimization. (<b>d</b>) Vertical displacement nephogram after optimization.</p>
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<p>Surrounding rock displacement.</p>
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<p>Surrounding rock displacement monitoring curve.</p>
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14 pages, 4295 KiB  
Article
Bio-Based Polyurethane–Urea with Self-Healing and Closed-Loop Recyclability Synthesized from Renewable Carbon Dioxide and Vanillin
by Tianyi Han, Tongshuai Tian, Shan Jiang and Bo Lu
Polymers 2024, 16(16), 2277; https://doi.org/10.3390/polym16162277 - 10 Aug 2024
Viewed by 1197
Abstract
Developing recyclable and self-healing non-isocyanate polyurethane (NIPU) from renewable resources to replace traditional petroleum-based polyurethane (PU) is crucial for advancing green chemistry and sustainable development. Herein, a series of innovative cross-linked Poly(hydroxyurethane-urea)s (PHUUs) were prepared using renewable carbon dioxide (CO2) and [...] Read more.
Developing recyclable and self-healing non-isocyanate polyurethane (NIPU) from renewable resources to replace traditional petroleum-based polyurethane (PU) is crucial for advancing green chemistry and sustainable development. Herein, a series of innovative cross-linked Poly(hydroxyurethane-urea)s (PHUUs) were prepared using renewable carbon dioxide (CO2) and vanillin, which displayed excellent thermal stability properties and solvent resistance. These PHUUs were constructed through the introduction of reversible hydrogen and imine bonds into cross-linked polymer networks, resulting in the cross-linked PHUUs exhibiting thermoplastic-like reprocessability, self healing, and closed-loop recyclability. Notably, the results indicated that the VL-TTD*-50 with remarkable hot-pressed remolding efficiency (nearly 98.0%) and self-healing efficiency (exceeding 95.0%) of tensile strength at 60 °C. Furthermore, they can be degraded in the 1M HCl and THF (v:v = 2:8) solution at room temperature, followed by regeneration without altering their original chemical structure and mechanical properties. This study presents a novel strategy for preparing cross-linked PHUUs with self-healing and closed-loop recyclability from renewable resources as sustainable alternatives for traditional petroleum-based PUs. Full article
(This article belongs to the Special Issue Preparation and Application of Biodegradable Polymeric Materials)
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<p>Schematic structure of VL-TTD* elastomers.</p>
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<p>(<b>a</b>) FTIR spectra of VL−C and VL−TTD*s; (<b>b</b>) FTIR spectra of VL−TTD*s; (<b>c</b>) swelling rates of the VL−TTD*s; (<b>d</b>) gel contents of the VL−TTD*s.</p>
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<p>Temperature-dependent <sup>1</sup>H NMR spectra of VL-TTD*-50 upon heating from 30 to 100 °C (<b>a</b>) and upon cooling from 100 to 30 °C (<b>b</b>).</p>
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<p>The rheology of VL-TTD*s: (<b>a</b>) Variation in the storage modulus as a function of the frequency and (<b>b</b>) variation in the loss modulus as a function of the frequency.</p>
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<p>(<b>a</b>) TGA and DTG curves of VL-TTD*s in N<sub>2</sub>; (<b>b</b>) DSC curves of VL-TTD*s; (<b>c</b>) stress–strain curves of VL-TTD*s; (<b>d</b>) mechanical properties of VL-TTD*s.</p>
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<p>(<b>a</b>) Photographs of the hot-pressing process. (<b>b</b>) FT-IR spectra of VL-TTD*-50 after two recycling processes; (<b>c</b>) stress–strain curves of VL-TTD*-50 after two recycling processes.</p>
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<p>(<b>a</b>) Polarizing optical microscopy images of the self-healing process of a crack on the VL-TTD*-50; (<b>b</b>) images of the self-healing of VL-TTD*-50: (i) original sample; (ii) cut segments; (iii) healed sample; (iv) the healed sample with the hanging weight of a 500 g bottle; (<b>c</b>) stress–strain curves of the VL-TTD*-50 after healing at different times.</p>
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<p>The self-healing mechanism of the VL-TTD*s.</p>
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<p>Closed-loop recycling of VL-TTD*s.</p>
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<p>(<b>a</b>) Degradation rate curves of VL-TTD*-50 in 1M HCl and THF (<span class="html-italic">v</span>:<span class="html-italic">v</span> = 2:8) and H<sub>2</sub>O/THF (<span class="html-italic">v</span>:<span class="html-italic">v</span> = 2:8); (<b>b</b>) FT-IR spectra of VL-TTD*-50, degraded products, and regenerated VL-TTD*-50; (<b>c</b>) stress–strain curves of original and regenerated VL-TTD*-50; (<b>d</b>) DSC curves of original and regenerated VL-TTD*-50.</p>
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<p>Synthetic routes of the VL-TTD*s.</p>
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16 pages, 69780 KiB  
Article
The 2024 Mw 7.1 Wushi Earthquake: A Thrust and Strike-Slip Event Unveiling the Seismic Mechanisms of the South Tian Shan’s Thick-Skin Tectonics
by Jiangtao Qiu, Jianbao Sun and Lingyun Ji
Remote Sens. 2024, 16(16), 2937; https://doi.org/10.3390/rs16162937 - 10 Aug 2024
Viewed by 1213
Abstract
The southern margin of the South Tian Shan has drawn attention due to the intense compressional deformation and seismic activity associated with its thrust structures. However, the deformation and seismic activity in the thick-skinned thrust sheets of the root zones are minimal. The [...] Read more.
The southern margin of the South Tian Shan has drawn attention due to the intense compressional deformation and seismic activity associated with its thrust structures. However, the deformation and seismic activity in the thick-skinned thrust sheets of the root zones are minimal. The Mw 7.1 Wushi earthquake on 23 January 2024 serves as a window to reveal these unknown aspects of the seismic mechanisms in this structural setting. Using the Leveraging Interferometric Synthetic Aperture Radar (InSAR) technique, we unlock critical insights into the coseismic deformation fields. The seismogenic fault is an unmapped segment within the Maidan Fault system, exhibiting a strike ranging from 241° to 222°. It is characterized by a shallow dip angle of 62° and a deeper dip angle of 56°. Remarkably, the seismic rupture did not propagate to the Earth’s surface. The majority of slip distribution is concentrated within a range of 4 to 26 km along the strike, indicating that this earthquake was a thrust event on a blind fault within the thick-skinned tectonics of the South Tian Shan. Coulomb stress changes indicate that aftershocks primarily occur in the stress-loading region. Interestingly, some aftershocks are very shallow, causing clear surface deformation. Inversion results show that the fault planes of two aftershocks are located above the main shock fault plane at extremely shallow depths (<6 km). Combining geophysical profile data, we infer that ruptures in the deep-seated thick-skinned structures during the main shock triggered ruptures in the shallow thrust structures. This triggering relationship highlights the potential for combined ruptures of the main shocks and aftershocks in the deep-seated thick-skinned structures beneath the South Tian Shan to result in larger disasters than typical seismic events. Full article
(This article belongs to the Special Issue Monitoring Geohazard from Synthetic Aperture Radar Interferometry)
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<p>Major Cenozoic faults in the Tianshan Zone and the tectonic setting of the 2024 Wushi earthquake. (<b>a</b>) The blue arrow indicates the GPS horizontal velocity field from [<a href="#B9-remotesensing-16-02937" class="html-bibr">9</a>]; the red arrow indicates the GPS horizontal velocity field from [<a href="#B10-remotesensing-16-02937" class="html-bibr">10</a>]; the thin black lines represent faults; the empty circles represent the locations of earthquakes with a magnitude of 6 or higher since 1900. (<b>b</b>) The red circular region delineates the area shown in (<b>a</b>); the gray circles represent the locations of strong earthquakes with a magnitude of 7 or higher since 1900 (data are from <a href="https://earthquake.usgs.gov/earthquakes/" target="_blank">https://earthquake.usgs.gov/earthquakes/</a>, accessed on 23 February 2024). (<b>c</b>) shows different organizations’ determined focal mechanism solutions and locations. (<b>d</b>) North–south structural diagram cross-section of the southern margin of the South Tian Shan. The light-blue line delineates the detachment fault. The red lines indicate the thrust faults of the southern margin of the South Tian Shan. Modified from [<a href="#B11-remotesensing-16-02937" class="html-bibr">11</a>,<a href="#B12-remotesensing-16-02937" class="html-bibr">12</a>]. The lemon chiffon area delineates thin skinned structure, medium purple area delineates thick skinned structure. Fault abbreviation: SNBF, the South Naryn Basin Fault; NNBF, the North Naryn Basin Fault; SIKF, the South Issyk-Kul Fault; PFF, the Pamir Frontal Thrust Fault; TFF, Talas-Fergana Fault; MDF, Maidan Fault; TSF, Toshgan Fault; KKSF, Kokesale Fault; NWSF the North Wensu Fault; KTF, Kepingtag Fault.</p>
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<p>Unwrapped InSAR deformation fields of the Wushi earthquake and aftershocks. (<b>a</b>,<b>b</b>) LOS deformation (cold colors indicate motion away from the satellite, while warm colors indicate motion towards the satellite). White lines denote of the surface trace of the seismogenic fault that we inferred. (<b>c</b>,<b>d</b>) Deformation profiles along A-A’ and B-B’ in (<b>a</b>,<b>b</b>). (<b>e</b>,<b>f</b>) InSAR deformation fields of aftershocks. The blue circles represent precise locations of aftershocks with depths less than 10 km and magnitudes greater than M4.5 between 24 January 2024 and 7 February 2024. The size of the circles corresponds to the magnitude of the aftershocks. Data source: <a href="https://data.earthquake.cn/gxdt/info/2024/334671642.html" target="_blank">https://data.earthquake.cn/gxdt/info/2024/334671642.html</a>, (accessed on 12 March 2024). (<b>e</b>) Ascending track 56, time interval 20240125_20240207. (<b>f</b>) Descending track 34, time interval 20240124_20240206.</p>
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<p>Marginal posterior probability distributions for the fault model parameters for the Wushi earthquake. Red lines represent the maximum a posteriori probability solution (cold colors for low frequency, warm colors for high frequency).</p>
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<p>Slip distribution model and deformation and residuals predicted of the Wushi Mw7.1 earthquake. (<b>a</b>) 3D display and (<b>b</b>) 2D display, arrows indicate the slip direction of the hanging wall relative to the footwall. (<b>c</b>,<b>f</b>) represent the observed values of ascending track 56 and descending track 34 after downsampling; (<b>d</b>,<b>g</b>) represent the predicted values; (<b>e</b>,<b>h</b>) represent the residual values. The red solid line indicates the determined trace of seismogenic fault.</p>
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<p>Estimated slip distribution and predicted deformation of the aftershocks. (<b>a</b>) A three-dimensional visualization showcasing the slip distribution of two faults. Red circles depict aftershock events occurring during the SAR imagery acquisition period. (<b>b</b>,<b>c</b>) Two-dimensional representations of the same slip distribution for enhanced clarity. (<b>d</b>–<b>f</b>) Observed deformation, simulated deformation, and residual errors derived from ascending track T56, respectively. (<b>g</b>–<b>i</b>) Similarly, the observed deformation, simulated deformation, and residual errors for descending track T34 are presented in sequence. The thin blue lines represent the seismogenic fault of the Wushi Mw 7.1 earthquake. The red solid line indicates the surface trace of f1 and f2 faults.</p>
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<p>(<b>a</b>) Coulomb stress triggering and (<b>b</b>) source structure locations of the main shock–aftershock sequence of the Wushi earthquake. (<b>a</b>) Changes in positive Coulomb stress (depicted in red) on the fault plane indicate proximity to failure and sliding hazard, while negative values (depicted in blue) signify a lack of sliding hazard. (<b>b</b>) The black lines represent the fault locations delineated based on the inversion of fault geometry parameters and geological cross-section base map (adapted from [<a href="#B27-remotesensing-16-02937" class="html-bibr">27</a>]). The red lines depict faults, the black line segments represent the mainshock fault and the aftershock (f1) fault identified in this study. Shallow light yellow areas indicate reverse-thrust overlying strata.</p>
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22 pages, 22089 KiB  
Article
Study on Spatial Distribution Dispersion Evaluation and Driving Forces of Rural Settlements in the Yellow River Basin
by Heying Li, Jianchen Zhang, Yamin Shan, Guangxia Wang, Qin Tian, Jiayao Wang and Huiling Ma
Land 2024, 13(8), 1181; https://doi.org/10.3390/land13081181 - 31 Jul 2024
Viewed by 723
Abstract
The spatial distribution pattern of rural settlements in the Yellow River Basin is scattered and numerous. It is of great significance to study the discrete distribution of rural settlements for achieving high-quality development and promoting rural revitalization strategy. In this paper, we propose [...] Read more.
The spatial distribution pattern of rural settlements in the Yellow River Basin is scattered and numerous. It is of great significance to study the discrete distribution of rural settlements for achieving high-quality development and promoting rural revitalization strategy. In this paper, we propose an enhanced evaluation model for assessing the spatial distribution dispersion of rural settlements, incorporating the weight of road grade (the road grade refers to the ranking of traffic capacity and importance of a particular type of road, indicating varying levels of time accessibility). We investigate the dispersion characteristics of rural settlements in the Yellow River Basin in 2020, focusing on both county and city scales. Furthermore, we conduct a comprehensive analysis of the spatial differentiation and scale effects of dispersion evaluation outcomes and their driving forces. Our findings reveal the following insights: (1) The road grade significantly influences the dispersion evaluation. When considering road grade in the dispersion calculation, the results align more closely with the actual situation. (2) The dispersion of rural settlements in the Yellow River Basin exhibits a decreasing trend from west to east. Specifically, the dispersion is higher in the upper reaches compared to the middle and lower reaches. Both city and county scales show spatial autocorrelation in dispersion, with a positive spatial correlation observed. High dispersion values cluster in the west, while low values concentrate in the east. Notably, the agglomeration degree is more pronounced at the county scale than at the city scale, highlighting more localized patterns of agglomeration and dispersion. (3) The multiscale geographically weighted regression model emerges as the optimal model for analyzing the driving forces of dispersion. At the city scale, factors such as river density, road density, and rural economy negatively impact dispersion. However, at the county scale, average elevation and rural economy positively affect dispersion, whereas river density, road density, and rural population density have a negative influence. By incorporating the weight of road grade into our evaluation model, we provide a more nuanced understanding of the spatial distribution dispersion of rural settlements in the Yellow River Basin. Our findings offer valuable insights for policymakers and planners seeking to optimize rural settlement patterns and promote sustainable rural development. Full article
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<p>Overview of study area.</p>
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<p>DCI indices system.</p>
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<p>Schematic diagram of rural settlements.</p>
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<p>DCI thematic map.</p>
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<p>DCI thematic map with considering road grades.</p>
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<p>DCI spatial distribution map ((<b>a</b>–<b>d</b>) represent the DCI values corresponding to the entire region, the upper reaches, the middle reaches, and the lower reaches of the Yellow River Basin, respectively).</p>
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<p>Spatial distribution of regression coefficient and significance at city scale in 2020.</p>
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<p>Spatial distribution of regression coefficient and significance at county scale.</p>
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<p>Moran scatter diagram of city-scale DCI in 2020.</p>
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<p>Moran scatter diagram of county-scale DCI in 2020.</p>
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<p>LISA cluster diagram of city-scale DCI in 2020.</p>
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<p>LISA cluster diagram of county-scale DCI in 2020.</p>
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22 pages, 22301 KiB  
Article
Projecting the Impacts of Climate Change, Soil, and Landscape on the Geographic Distribution of Ma Bamboo (Dendrocalamus latiflorus Munro) in China
by Li-Jia Chen, Yan-Qiu Xie, Tian-You He, Ling-Yan Chen, Jun-Dong Rong, Li-Guang Chen and Yu-Shan Zheng
Forests 2024, 15(8), 1321; https://doi.org/10.3390/f15081321 - 29 Jul 2024
Cited by 1 | Viewed by 801
Abstract
Ma bamboo (Dendrocalamus latiflorus Munro) is a fast-growing woody grass that offers significant economic benefits, including materials for construction, furniture, biofuel, food, and handicrafts. It also provides ecological benefits like soil conservation, wildlife habitats, and carbon sequestration. However, its species distribution patterns [...] Read more.
Ma bamboo (Dendrocalamus latiflorus Munro) is a fast-growing woody grass that offers significant economic benefits, including materials for construction, furniture, biofuel, food, and handicrafts. It also provides ecological benefits like soil conservation, wildlife habitats, and carbon sequestration. However, its species distribution patterns are influenced by various factors, including climate (mainly temperature and precipitation), soil attributes, and landscape characteristics such as topography, land use, and vegetation. Understanding these impacts is essential for the sustainable management of D. latiflorus resources and fostering related economic activities. To address these challenges, we developed a comprehensive habitat suitability (CHS) model that integrates climate, soil, and landscape variables to simulate the distribution dynamics of D. latiflorus under different shared socio-economic pathway (SSP) scenarios. An ensemble model (EM) strategy was applied to each variable set to ensure robust predictions. The results show that the current potential distribution of D. latiflorus spans 28.95 × 104 km2, primarily located in South China and the Sichuan Basin. Its distribution is most influenced by the annual mean temperature (Bio1), the cation exchange capacity of soil clay particles in the 20–40 cm soil layer (CECc 20–40 cm), vegetation, and elevation. Under future climate scenarios, these habitats are projected to initially expand slightly and then contract, with a northward shift in latitude and migration to higher elevations. Additionally, the Sichuan Basin (Sichuan–Chongqing border) is identified as a climatically stable area suitable for germplasm development and conservation. To conclude, our findings shed light on how climate change impacts the geographic distribution of D. latiflorus, providing key theoretical foundations for its sustainable cultivation and conservation strategies. Full article
(This article belongs to the Section Forest Ecology and Management)
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<p>Methodological approaches for comprehensive habitat suitability evaluation.</p>
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<p>Occurrence data (165 points) of <span class="html-italic">D. latiflorus</span> in China.</p>
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<p>Variable importance and response curves of key climate and soil variables in the modeled distribution of <span class="html-italic">D. latiflorus</span> based on ensemble models. (<b>a</b>) Single variable importance of climate EM; (<b>b</b>) response curve of Bio1; (<b>c</b>) bivariate response curves of Bio1 and Bio12; (<b>d</b>) single variable importance of soil EM; (<b>e</b>) response curve of CECc 20–40 cm; (<b>f</b>) bivariate response curves of CECc 20–40 cm and ECEC 0–20 cm.</p>
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<p>Response curves of key environmental variables for the modeled distribution of <span class="html-italic">D. latiflorus</span> using the MaxEnt algorithm. (<b>a</b>) Vegetation; (<b>b</b>) elevation.</p>
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<p>Comprehensive habitat suitability area of <span class="html-italic">D. latiflorus</span> in the current period.</p>
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<p>Areas of unsuitable, moderately suitable, and highly suitable regions for <span class="html-italic">D. latiflorus</span> under different scenarios.</p>
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<p>Changes in areas and patterns of <span class="html-italic">D. latiflorus</span> from current to future scenarios. (<b>a</b>) Percentage of habitats with different suitability under future scenarios; (<b>b</b>) percentage of pattern changes under future scenarios; (<b>c</b>) area changes under different GHG emission scenarios; (<b>d</b>) area changes across different periods.</p>
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<p>Areas of expansion and contraction and unchanged regions for <span class="html-italic">D. latiflorus</span> under different scenarios.</p>
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<p>Core shift of potential suitable habitats for <span class="html-italic">D. latiflorus</span> from current to future scenarios.</p>
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<p>Low-Impact Areas of <span class="html-italic">D. latiflorus</span> from current to future scenarios. (<b>a</b>) Primary Low-Impact Areas in the Sichuan basin (Sichuan and Chongqing); (<b>b</b>) Primary Low-Impact Areas in southwestern and southern China (Yunnan, Guizhou, Guangxi, and Hainan); (<b>c</b>) Primary Low-Impact Areas in southeastern China (Guangdong, Fujian, and Taiwan).</p>
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<p>Latitude and elevation variations of suitable habitats for <span class="html-italic">D. latiflorus</span> under different scenarios compared to current condition.</p>
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13 pages, 16054 KiB  
Article
Expression of Iron Metabolism Genes Is Potentially Regulated by DOF Transcription Factors in Dendrocalamus latiflorus Leaves
by Peng-Kai Zhu, Mei-Xia Lin, Mei-Yin Zeng, Yu Tang, Xin-Rui Li, Tian-You He, Yu-Shan Zheng and Ling-Yan Chen
Int. J. Mol. Sci. 2024, 25(15), 8114; https://doi.org/10.3390/ijms25158114 - 25 Jul 2024
Viewed by 676
Abstract
Transcription factors (TFs) are crucial pre-transcriptional regulatory mechanisms that can modulate the expression of downstream genes by binding to their promoter regions. DOF (DNA binding with One Finger) proteins are a unique class of TFs with extensive roles in plant growth and development. [...] Read more.
Transcription factors (TFs) are crucial pre-transcriptional regulatory mechanisms that can modulate the expression of downstream genes by binding to their promoter regions. DOF (DNA binding with One Finger) proteins are a unique class of TFs with extensive roles in plant growth and development. Our previous research indicated that iron content varies among bamboo leaves of different colors. However, to our knowledge, genes related to iron metabolism pathways in bamboo species have not yet been studied. Therefore, in the current study, we identified iron metabolism related (IMR) genes in bamboo and determined the TFs that significantly influence them. Among these, DOFs were found to have widespread effects and potentially significant impacts on their expression. We identified specific DOF members in Dendrocalamus latiflorus with binding abilities through homology with Arabidopsis DOF proteins, and established connections between some of these members and IMR genes using RNA-seq data. Additionally, molecular docking confirmed the binding interactions between these DlDOFs and the DOF binding sites in the promoter regions of IMR genes. The co-expression relationship between the two gene sets was further validated using q-PCR experiments. This study paves the way for research into iron metabolism pathways in bamboo and lays the foundation for understanding the role of DOF TFs in D. latiflorus. Full article
(This article belongs to the Special Issue Transcription Factors in Plant Gene Expression Regulation)
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<p>The number of IMR genes in different metabolic categories of <span class="html-italic">D. latiflorus</span>.</p>
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<p>The number of TFBS from different TF families in IMR gene promoter regions (<b>A</b>), and the number of IMR genes in the promoter regions of each TF family that have binding sites (<b>B</b>).</p>
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<p>The phylogenetic relationship, conserved motifs, and multiple alignment diagram of 93 DlDOFs.</p>
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<p>Transcriptome analysis of genes in <span class="html-italic">D. latiflorus</span> leaves. Expression heatmap of DlDOFs in leaves (<b>A</b>). Expression heatmap of IMR genes in leaves (<b>B</b>). Co-expression network of DlDOFs and IMR genes (<b>C</b>). Leaf1, Leaf2, and Leaf3 refer to mature leaves collected from three different <span class="html-italic">D. latiflorus</span> cutting seedlings.</p>
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<p>Key DlDOFs; selection and molecular docking. Venn diagram illustrating co-expression and potential regulatory relationships between DlDOFs and IMR genes through promoter binding (<b>A</b>). Green circles represent the number of co-expression relationships, while magenta circles represent potential regulatory relationships. Protein-DNA interaction models (<b>B</b>). Text below the model indicates the motif types present in TFBS and the binding of DlDOFs to IMR gene promoters.</p>
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<p>Relative expression patterns of two DlDOFs and three IMR genes in leaves.</p>
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27 pages, 29974 KiB  
Article
Evidence of Dextral Strike-Slip Movement of the Alakol Lake Fault in the Western Junggar Based on Remote Sensing
by Wenxing Yi, An Li, Liangxin Xu, Zongkai Hu and Xiaolong Li
Remote Sens. 2024, 16(14), 2615; https://doi.org/10.3390/rs16142615 - 17 Jul 2024
Viewed by 625
Abstract
The NW-SE-trending dextral strike-slip faults on the north side of the Tian Shan, e.g., the Karatau fault, Talas–Fergana fault, Dzhalair–Naiman fault, Aktas fault, Dzhungarian fault, and Chingiz fault, play an important role in accommodating crustal shortening. The classic viewpoint is that these strike-slip [...] Read more.
The NW-SE-trending dextral strike-slip faults on the north side of the Tian Shan, e.g., the Karatau fault, Talas–Fergana fault, Dzhalair–Naiman fault, Aktas fault, Dzhungarian fault, and Chingiz fault, play an important role in accommodating crustal shortening. The classic viewpoint is that these strike-slip faults are an adjustment product caused by the difference in the crustal shortening from west to east. Another viewpoint attributes the dextral strike-slip fault to large-scale sinistral shearing. The Alakol Lake fault is a typical dextral strike-slip fault in the north Tian Shan that has not been reported. It is situated along the northern margin of the Dzhungarian gate, stretching for roughly 150 km from Lake Ebinur to Lake Alakol. Our team utilized aerial photographs, satellite stereoimagery, and field observations to map the spatial distribution of the Alakol Lake fault. Our findings provided evidence supporting the assertion that the fault is a dextral strike-slip fault. In reference to its spatial distribution, the Lake Alakol is situated in a pull-apart basin that lies between two major dextral strike-slip fault faults: the Chingiz and Dzhungarian faults. The Alakol Lake fault serves as a connecting structure for these two faults, resulting in the formation of a mega NW-SE dextral strike-slip fault zone. According to our analysis of the dating samples taken from the alluvial fan, as well as our measurement of the displacement of the riser and gully, it appears that the Alakol Lake fault has a dextral strike-slip rate of 0.8–1.2 mm/a (closer to 1.2 mm/a). The strike-slip rate of the Alakol Lake fault is comparatively higher than that of the Chingiz fault in the northern region (~0.7 mm/a) but slower than that of the Dzhungarian fault in the southern region (3.2–5 mm/a). The Chingiz–Alakol–Dzhungarian fault zone shows a gradual decrease in deformation towards the interior of the Kazakhstan platform. Full article
(This article belongs to the Special Issue Remote Sensing for Geology and Mapping)
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<p>(<b>a</b>) The digital elevation model shows the distribution of the main Quaternary faults in the northern Tian Shan region (modified after Xu et al., 2016) [<a href="#B34-remotesensing-16-02615" class="html-bibr">34</a>]. Blue arrows show the GPS measurements from Wang and Shen (2020) [<a href="#B23-remotesensing-16-02615" class="html-bibr">23</a>]. The blue dashed lines (A–A’) show the locations of the GPS profiles. The white circles show the major cities. The black dashed boxes show the locations of <a href="#remotesensing-16-02615-f002" class="html-fig">Figure 2</a>. DZF—Dzhungarian fault; ALF—Alakol Lake fault; CF—Chingiz fault; KSHF—Kashihe fault; ETF—East Tacheng fault; TLF—TuoLi fault; and DF—Daerbute fault. (<b>b</b>) The global digital elevation model shows the tectonic location of the research area (<b>a</b>). (<b>c</b>) Swath GPS profile A–A’ shows the velocity components parallel to (blue dots) the profile striking N320°W [<a href="#B20-remotesensing-16-02615" class="html-bibr">20</a>]. The brown line and gray shadow show the mean value and range of elevation with 50 km width along the profile A–A’. The blue-shaded rectangles are the visually fitted range of the GPS velocities. The blue letters and numbers represent the GPS observation stations’ abbreviations.</p>
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<p>The extension of the Alakol Lake fault is shown on Google Earth. The red lines show the location of the fault trace. The red triangular arrows indicate dextral strike-slip movement. The black boxes are the study sites. The white circles show the major cities.</p>
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<p>Field collection locations of the OSL samples: (<b>a</b>) sample AL-01; (<b>b</b>) sample AL-02; (<b>c</b>) sample AL-03; and (<b>d</b>) sample AL-04. (<b>e</b>) The field site shows a dextral alluvial fan and the fault scarp, which is also where the sample AL-04 was collected. (<b>f</b>) Sample AL-05. (<b>g</b>) The field site indicates the fault trace and fault scarp, which is also where the sample AL-05 was collected. The red triangular arrows indicate the fault trace.</p>
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<p>Site 1: (<b>a</b>) The hillshade map, which was built from a high-resolution UAV DEM using ArcGIS 10.8, shows structural and geomorphological characters of the Alakol Lake fault. The red lines are the fault trace. The red dotted lines show that the fault traces are either unclear or covered. The red triangular arrows indicate dextral strike-slip movement. The black solid line (A–A’) marks the location of the profile in (<b>c</b>). Four stages of alluvial fans (T1–T4) are developed along the stream channel, and the shadows with different colors depict the corresponding alluvial fans. The white dashed lines and the pink dashed lines represent the fit lines of the T4 riser. The white dotted box represents the range of (<b>b</b>). (<b>b</b>) The image of the hillshade map displays a detailed view of the geomorphic surface in (<b>a</b>). The white and pink dashed lines in the image represent the fit lines. The white and pink arrows indicate the preferred offset. (<b>c</b>) Topographic profile across the fault extracted from the UAV DEM was used to measure the vertical offset. The blue dashed lines are fit lines. (<b>d</b>) The field photo shows the fault trace and alluvial fans. The white oval highlights the house for scale. (<b>e</b>) The field photo was shot in the northwest. The red dashed line represents the fault. Q represents the alluvial fan deposits (probably middle–upper Pleistocene), N represents the Neogene sandstone, and C represents the Carboniferous granite.</p>
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<p>Site 2: (<b>a</b>) The hillshade map image, which was made using the high-resolution UAV DEM, shows the geomorphological expression of the Alakol Lake fault. The red lines are the fault trace. The red triangular arrows indicate dextral strike-slip movement. The two blue curves represent the horizontal offset of the gullies. The orange curve represents the dextrally displaced ridge. The black solid lines (A–A’ and B–B’) indicate the location of the extracted fault scarp. All of the white dashed lines represent the fit lines. The white arrows indicate the preferred offset. (<b>b</b>) Two topographic profiles across the fault extracted from the UAV DEM were used to measure the vertical offset. The blue dashed lines are fit lines. (<b>c</b>) The field photo shows the dextrally displaced ridge. The dotted orange lines show the location of the ridge. The red triangles indicate the fault trace. The blue dashed line indicates the dextral channel. The white ovals highlight the people for scale.</p>
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<p>Site 3: (<b>a</b>) The hillshade map image, which was made using the high-resolution UAV DEM, shows the geomorphological expression of the Alakol Lake fault. The red lines are the fault trace, and the scales indicate the slope direction of the fault scarp. The red triangular arrows indicate dextral strike-slip movement. The black dotted box represents the range of Figure c. The orange shadows represent T1, and purple shadows represent T2. The blue curves represent the dextrally displaced edge of the alluvial fans, and the white dashed lines represent the fit lines. The white arrows indicate the preferred offset. The black solid lines (A–A’ and B–B’) indicate the location of the extracted fault scarps. (<b>b</b>) Topographic profiles across the fault extracted from the UAV DEM were used to measure the vertical offset. The blue dashed lines are fit lines. (<b>c</b>) A photo taken by the drone shows the fault traces and a pull-apart basin.</p>
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<p>Site 4: (<b>a</b>) The hillshade map image, which was made using the high-resolution UAV DEM, shows the geomorphological expression of the Alakol Lake fault. The red line is the fault trace, and the scales indicate the slope direction of the fault scarp. Two red triangular arrows indicate dextral strike-slip movement. The orange shadow represents T1, and the purple shadows represent T2. The blue curves with arrows represent the dextrally displaced gullies, and the white dashed lines represent the fit lines. The white arrows indicate the preferred offset. The spring symbol composed of the blue circle and blue curve indicates the location of the fault spring. The black solid lines (A–A’, B–B’) indicate the location of the extracted fault scarps. The black dotted box represents the range of (<b>b</b>,<b>c</b>). (<b>b</b>) The enlarged hillshade map image shows the more detailed geomorphic surface in (<b>a</b>). Four identical red triangles indicate the fault trace. (<b>c</b>) A field photo of the range corresponding to (<b>b</b>). (<b>d</b>) Topographic profiles across the fault extracted from the UAV DEM were used to measure the vertical offset. The blue dashed lines are fit lines. (<b>e</b>) The field photo shows the dextrally displaced gully and fault scarp. (<b>f</b>) The field photo shows the fault scarp. The dotted white line indicates the geomorphic surface. Two red arrows show the fault scarp. (<b>g</b>) The picture shows the fault spring in the field.</p>
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<p>Site 5: (<b>a</b>) The hillshade map image, which was made using the high-resolution UAV DEM, shows the geomorphological expression of the Alakol Lake fault. Different colored shadows represent different alluvial fans. The red lines indicate clear fault traces, while the red dotted lines show fault traces that are either not visible or are covered. The white arrows indicate the preferred offset. The red triangular arrows indicate dextral strike-slip movement. The scales indicate the slope direction of the fault scarp. The white dashed lines represent the dextrally displaced T2 alluvial fan. The black solid lines (A–A’, B–B’) indicate the location of the extracted fault scarps. (<b>b</b>) Topographic profiles across the fault extracted from the UAV DEM were used to measure the vertical offset. The blue dashed lines are fit lines. (<b>c</b>) The field photo shows the fault trace and the different alluvial fans. The red arrows indicate the fault scarp and fault trace, and the white circle represents the iron tower as a reference.</p>
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<p>Site 6: (<b>a</b>) View of the Pleiades DEM shows the geomorphological expression of the Alakol Lake fault. (<b>b</b>) Hillshade map image, which was made using the high-resolution UAV DEM, shows the enlarged geomorphic surface. The red lines are the fault traces, and the red dotted lines show that the fault traces are not clear or are covered. The red triangular arrows indicate dextral strike-slip movement. The scales indicate the slope direction of the fault scarp. Different colored shadows represent different alluvial fans. The green curve represents the dextrally displaced alluvial fan. The blue curve represents the dextrally displaced gullies. All of the white dashed lines represent the fit lines. The white arrows indicate the preferred offset. (<b>c</b>,<b>d</b>) The fault breccia indicated by the white arrow revealed in the field.</p>
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<p>Site 7: (<b>a</b>) View of the Pleiades DEM shows some displaced alluvial fans. The translucent green shades are the alluvial fans. The red lines are the fault traces, and the red triangular arrows indicate dextral strike-slip movement. The blue curves represent the stream channels. (<b>b</b>) Hillshade map image, which was made by the high-resolution UAV DEM, shows the geomorphic surface of enlarged alluvial fan 2. (<b>c</b>) The outline of alluvial fans identified based on the texture and color characteristics in the Pleiades satellite image.</p>
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<p>Site 8: (<b>a</b>) View of the Pleiades DEM shows the fault trace and the displaced geomorphic surface. The red triangles indicate the fault trace. The blue dashed lines indicate the displaced gullies, while the yellow dashed lines indicate the displaced T3 riser. (<b>b</b>) View of the enlarged geomorphic surface shows the displaced gullies. The red triangular arrows indicate dextral strike-slip movement. (<b>c</b>) The back-slipped view of the gullies.</p>
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<p>Site 9: (<b>a</b>) The location of site 9 is shown on Google Earth. (<b>b</b>) The fault trace and geomorphic surface are shown on Google Earth. Six identical red triangles indicate the fault trace. Two red triangular arrows indicate dextral strike-slip movement. The black solid lines (A–A’ and B–B’) show where the topographic profiles were extracted. The white boxes represent the viewing areas of (<b>d</b>,<b>e</b>). (<b>c</b>) Topographic profiles (A–A’ and B–B’) across the fault extracted from the DEM were used to measure the vertical offset. The blue dashed lines are fit lines. (<b>d</b>,<b>e</b>) Some images of the displaced gullies taken on Google Earth. The blue dashed lines indicate the displaced gullies. The white dashed lines represent the fit lines. The white arrows indicate the preferred offset.</p>
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<p>(<b>a</b>) Simplified geological model map of the new fault in the western Junggar. The white arrows indicate the relative movement directions of the Tacheng Basin, Junggar Alatau, and Junggar Basin. DZF—Dzhungarian fault; ALF—Alakol Lake fault; CF—Chingiz fault; LF—Lepsy fault; KSHF—Kashihe fault; DF—Daerbute fault; TLF—TuoLi fault; ETF—East Tacheng fault; and NTF—North Tacheng fault. (<b>b</b>) Evolutionary model map of Lake Alakol and the Alakol Lake fault.</p>
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17 pages, 6422 KiB  
Article
Mechanism of Abnormal Activation of MEK1 Induced by Dehydroalanine Modification
by Yue Zhao, Shan-Shan Du, Chao-Yue Zhao, Tian-Long Li, Si-Cheng Tong and Li Zhao
Int. J. Mol. Sci. 2024, 25(13), 7482; https://doi.org/10.3390/ijms25137482 - 8 Jul 2024
Cited by 1 | Viewed by 757
Abstract
Mitogen-activated protein kinase kinase 1 (MAPK kinase 1, MEK1) is a key kinase in the mitogen-activated protein kinase (MAPK) signaling pathway. MEK1 mutations have been reported to lead to abnormal activation that is closely related to the malignant growth and spread of various [...] Read more.
Mitogen-activated protein kinase kinase 1 (MAPK kinase 1, MEK1) is a key kinase in the mitogen-activated protein kinase (MAPK) signaling pathway. MEK1 mutations have been reported to lead to abnormal activation that is closely related to the malignant growth and spread of various tumors, making it an important target for cancer treatment. Targeting MEK1, four small-molecular drugs have been approved by the FDA, including Trametinib, Cobimetinib, Binimetinib, and Selumetinib. Recently, a study showed that modification with dehydroalanine (Dha) can also lead to abnormal activation of MEK1, which has the potential to promote tumor development. In this study, we used molecular dynamics simulations and metadynamics to explore the mechanism of abnormal activation of MEK1 caused by the Dha modification and predicted the inhibitory effects of four FDA-approved MEK1 inhibitors on the Dha-modified MEK1. The results showed that the mechanism of abnormal activation of MEK1 caused by the Dha modification is due to the movement of the active segment, which opens the active pocket and exposes the catalytic site, leading to sustained abnormal activation of MEK1. Among four FDA-approved inhibitors, only Selumetinib clearly blocks the active site by changing the secondary structure of the active segment from α-helix to disordered loop. Our study will help to explain the mechanism of abnormal activation of MEK1 caused by the Dha modification and provide clues for the development of corresponding inhibitors. Full article
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<p>MAPK signaling pathway.</p>
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<p>(<b>A</b>) Representation of MEK1 and its functional domains. (<b>B</b>) Time-dependent changes in the root mean square deviation (RMSD) values during the molecular dynamics (MD) simulations. (<b>C</b>) Root mean square fluctuation (RMSF) of the protein backbone after 200 ns of MD simulations.</p>
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<p>Dynamic changes in the secondary structures of the active segment throughout the entire simulation process, (<b>A</b>) WT_MEK1, (<b>B</b>) PP MEK1, and (<b>C</b>) Dha MEK1.</p>
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<p>(<b>A</b>–<b>C</b>) FEL analysis of the WT_MEK1, PP_MEK1 and Dha_MEK1 respectively. The energy-minimized representative conformations are shown, with the active segment highlighted in red and the rest of the conformations colored in gray using a cartoon representation. (<b>D</b>) Comparison of representative structures of the WT_MEK1 and Dha_MEK1 systems (blue helix: active segment of WT_MEK1, pink helix: active segment of Dha_MEK1). The catalytic site (Asp190) is depicted as a sphere (light green), and ATP and Mg<sup>2+</sup> ions are shown as sticks (colored according to the elements). (<b>E</b>) Hedgehog plot of MEK1 based on the first principal component (PC) of the WT_MEK1, PP_MEK1, and Dha_MEK1, with arrows indicating the direction and magnitude of motion trends.</p>
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<p>The contact number variation over time between (<b>A</b>) the active segment and the N-terminal and (<b>B</b>) the active segment and the C-terminal.</p>
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<p>Structure and volume of the active pocket. (<b>A</b>) WT_MEK1 and (<b>B</b>) Dha_MEK1 active pocket structure. The representative conformation is obtained through conformation clustering and represents the highest probability conformation, confirming the stability of the observed states. (<b>C</b>) Representation of the active pocket with key catalytic residue Asp190 highlighted (red sphere). (<b>D</b>) WT_MEK1, (<b>E</b>) PP_MEK1 and (<b>F</b>) Dha_MEK1 catalytic pocket volume. (<b>G</b>) Variation in the catalytic pocket volume over time. (<b>H</b>) Probability distribution of the catalytic pocket volume.</p>
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<p>(<b>A</b>) Representation of G×G××G domain (light blue), the C-helix (green), and the active segment (pink). (<b>B</b>) Visualization of the distance between the C-helix and the active segment and its variation over time. (<b>C</b>) Visualization of the distance between the G×G××G domain and the active segment and its variation over time. (<b>D</b>) Visualization of the distance between the C-helix and the G×G××G domain and its variation over time.</p>
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<p>Electrostatic potential surfaces (EPS) colored based on the electrostatic potential of (<b>A</b>) WT_MEK1, (<b>B</b>) PP_MEK1 and (<b>C</b>) Dha_MEK1. In the figures, the positions of Ser218 and Ser222 in the active segment are enclosed in black circles and the F-helix is outlined in green. The red color corresponds to ESP values below −64.457 kcal/e.u, the blue color corresponds to ESP values above +64.457 kcal/e.u, and the gray color corresponds to ESP values between −64.457 and +64.457 kcal/e.u.</p>
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<p>Structural representations of hydrogen bonds. (<b>A</b>) WT_MEK1, (<b>B</b>) PP_MEK1, and (<b>C</b>) Dha_MEK1. MEK1 is depicted in gray cartoon representation, with the C-helix highlighted in blue, the active segment in green, and the F-helix in pink. Amino acid residues are represented by red spheres, and the interactions are indicated by black arrows.</p>
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<p>The Free energy landscapes of (<b>A</b>) WT_MEK1, (<b>B</b>) PP_MEK1 and (<b>C</b>) Dha_MEK1, along with the one-dimensional projections of the two collective variables (CVs). (<b>D</b>) Representative conformation corresponding to the energy minima in the Dha_MEK1 system.</p>
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<p>Representation and probability distribution of the dihedral angles (<b>A</b>) <span class="html-italic">φ</span>, (<b>B</b>) <span class="html-italic">ϕ</span> and (<b>C</b>) Cα-Cβ. Probability distributions shown in unit circle are for residues at positions 218 (left) and 222 (right).</p>
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<p>(<b>A</b>) RMSD of Dha_MEK1 and Dha_MEK1 with four inhibitor complexes. (<b>B</b>) RMSF and the secondary structure of the active segment (Val211-Tyr236). (<b>C</b>) Time-dependent changes in the secondary structure of the active segment (Phe209-Met219). (<b>D</b>) Representation of clustered conformations, active segment was highlighted in gray, red, dark blue and orange for Dha_MEK1, Dha_MEK1_Tra, Dha_MEK1_Sel, Dha_MEK1_Cob and Dha_MEK1_Bin respectively. The plots were created using LigPlot [<a href="#B41-ijms-25-07482" class="html-bibr">41</a>].</p>
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<p>The interactions between Dha_MEK1 and Trametinib, Selumetinib, Cobimetinib and Binimetinib respectively. Residues involved in hydrogen bond and ligand binding are shown as stick models, while non-bonded interactions are depicted as red brush-like structures. Hydrogen bonds are depicted as green dashed lines with corresponding bond lengths in angstroms (Å). Carbon atoms are represented as black spheres, nitrogen atoms as blue spheres, oxygen atoms as red spheres, fluorine atoms as pink spheres and phosphorus atoms as purple spheres.</p>
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<p>Representation of the conformational distribution of the active segment in the catalytic region binding with Trametinib, Selumetinib, Cobimetinib and Binimetinib respectively. Asp190 is represented in surface colored in red, the ATP is in licorice colored in orange, the Mg<sup>2+</sup> ions are represented by van der Waals spheres, colored in light blue. The four inhibitors in the active pocket are drawn in licorice, and the atoms different of oxygens are colored in red (Trametinib), orange (Selumetinib and Cobimetinib) and light blue (Binimetinib). The other protein residues are drawn by surface colored in beige.</p>
Full article ">Figure 15
<p>(<b>A</b>) Schematic representation of MEK1 structure. (<b>B</b>) Structure of MEK1 with active segment highlighted (wild-type, phosphorylated and Dha-modified Ser218 and Ser222 are shown, respectively).</p>
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