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Background/Objectives: Becoming an elite canoe slalom athlete requires thousands of hours of training, spread over many years. It is difficult to assess the correct balance between flatwater and whitewater training because differences in the paddle forces on these terrains are not known. The aim of this study was to describe paddle forces during canoe slalom training on flatwater and whitewater courses for the C1 canoe category. Methods: Paddle forces for twenty C1 canoe slalom athletes were quantified during all-out figure-of-eight tests on a flatwater course and during race simulations on a whitewater course. Paddle forces were measured using strain gauges embedded in the paddle shaft and quantified by their force, impulse, and stroke durations. Results: The mean force during the pull phase of the paddle strokes was not significantly different between the flatwater and whitewater courses; however, the longer pull phase durations led to a greater pull phase impulse when paddling on the whitewater course. Conclusions: This study indicates that training for all-out runs on a whitewater course is more demanding for canoe slalom athletes than performing all-out trials on a flatwater figure-of-eight course. This evidence may help to develop effective training plans that are essential to reach the highest levels of the sport. Full article

(This article belongs to the Special Issue Biomechanical Analysis in Physical Activity and Sports)

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Distribution of pull duration, transition time, impulse, and paddle force for the twenty athletes. Strokes for flatwater training are shown in black, and those for whitewater training are in grey. Full article ">Figure 2
Mean stroke parameters (with standard error of mean). Strokes for flatwater training are shown in black, and those for whitewater training are in grey. Full article ">

11 pages, 610 KiB

Open AccessArticle

Necessary and Sufficient Criteria for a Four-Weight Weak-Type Maximal Inequality in the Orlicz Class

by Erxin Zhang

Axioms 2024, 13(9), 635; https://doi.org/10.3390/axioms13090635 (registering DOI) - 17 Sep 2024

Abstract

Let

Φ_{i} (i = 1, 2)

be two N-functions, f be a

μ

-measurable function, and

ω_{i} (i = 1, 2, 3, 4)

be four weight functions. This study presents necessary and [...] Read more.

Let

Φ_{i} (i = 1, 2)

be two N-functions, f be a

μ

-measurable function, and

ω_{i} (i = 1, 2, 3, 4)

be four weight functions. This study presents necessary and sufficient conditions for weight functions

(ω_{1}, ω_{2}, ω_{3}, ω_{4})

such that the inequality

\int_{{x : M f (x) > λ}} Φ_{1} (λ ω_{1} (x)) ω_{2} (x) d μ (x) \leq c_{1} \int_{X} Φ_{2} (c_{1} | f (x) | ω_{3} (x))

ω_{4} (x) d μ (x)

holds, which extends several established results. Full article

(This article belongs to the Special Issue Theory of Functions and Applications II)

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Equivalence relation graph. Full article ">

14 pages, 4623 KiB

Open AccessArticle

Synergic Effects of Ordered Mesoporous Bifunctional Ionic Liquid: A Recyclable Catalyst to Access Chemoselective N-Protected Indoline-2,3-dione Analogous

by Gouthaman Siddan and Viswas Raja Solomon

Catalysts 2024, 14(9), 629; https://doi.org/10.3390/catal14090629 (registering DOI) - 17 Sep 2024

Abstract

SBA-15 and organic ionic liquid were incorporated in a post-grafting technique for generating a bifunctional ionic liquid embedded mesoporous SBA-15. The prepared heterogeneous catalyst was employed for the first time to synthesize N-alkylated indoline-2,3-dione at mild conditions to afford excellent yields in a short reaction time. The synthesized DABCOIL@SBA-15 catalyst was meticulously characterized by various techniques, such as FT-IR, solid-state ¹³C NMR, solid-state ²⁹Si NMR, small-angle X-ray diffraction (XRD), and N₂ adsorption–desorption. Further, the morphological behavior of the catalyst was studied by SEM and TEM. The thermal stability and number of active sites were determined by thermogravimetric analysis (TGA). The Hammett equation was used to analyze the synergetic effect of the catalyst and substituent effects on the N-alkylated products of 5-substituted isatin derivatives, which resulted in a negative slope. This negative slope indicates a positive charge in the transition state. Notably, the DABCOIL@SBA-15 catalyst demonstrated its practicality by being reused for seven cycles with consistently high catalytic activity. Full article

(This article belongs to the Special Issue Mesoporous Nanostructured Materials for Heterogeneous Catalysis)

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10 pages, 1547 KiB

Open AccessArticle

Comparative Study of the Antioxidant Activity of the Conformers of C-tetra(4-methoxyphenyl)calix[4]resorcinarene

by Laura Angélica Maldonado-Sanabria, Ivette Nicole Rodriguez-Saavedra, Ingrid Valentina Reyes-Peña, Alver Castillo-Aguirre, Mauricio Maldonado, Almudena Crespo and Miguel A. Esteso

Int. J. Mol. Sci. 2024, 25(18), 10010; https://doi.org/10.3390/ijms251810010 (registering DOI) - 17 Sep 2024

Abstract

C-tetra(4-methoxyphenyl)calix[4]resorcinarene was synthesized by hydrochloric acid-catalysed cyclocondensation of resorcinol and 4-methoxybenzaldehyde. Under these conditions, the reaction produces a conformational mixture of crown and chair structural conformers, which were separated and characterized by chromatographic and spectroscopic techniques. The antioxidant activity of both conformers was measured by using the DPPH assay, through which it was observed that the chair conformer showed greater antioxidant activity (IC₅₀ = 47.46 ppm) than the crown conformer (IC₅₀ = 78.46 ppm). Additionally, it was observed that the mixture of both conformers presented lower antioxidant activity than either conformer in isolation. The results found suggest that the chair conformer has efficient antioxidant activity that makes it a potential target for further research. Full article

(This article belongs to the Special Issue Recent Insights on Macrocyclic-Based Hybrid Assemblies with Stimuli-Responsiveness)

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Chromatograms of the separation, via HPLC, of C-tetra(4-methoxyphenyl)calix[4]resorcinarene: (a) the conformational mixture, (b) the chair conformer and (c) the crown conformer. Full article ">Figure 2
1H-NMR C-tetra(4-methoxyphenyl)calix[4]resorcinarene: crown conformer (1a) and chair conformer (1b). Signals a, b and c (in red) correspond to protons a, b and c of the resorcinol residue. Full article ">Figure 3
DPPH free radical inhibition for 1:1 conformer mixture, individual C-tetra(4-methoxyphenyl)calix[4]resorcinarene conformers (chair and crown) and positive control (ascorbic acid). Full article ">Figure 4
Fa–CI plot of the conformational mixture to evaluate antagonism. The combination index (CI) values are represented on the y-axis and the affected fraction (Fa) on the x-axis. Full article ">Figure 5
Hydrogen bonding interactions for 1a (a), 1b (b) and the conformational mixture (c). Full article ">Scheme 1
Synthesis of C-tetra(4-methoxyphenyl)calix[4]resorcinarene, including the crown (1a) and chair (1b) conformers. Full article ">

18 pages, 1763 KiB

Open AccessArticle

In Vitro Study of Cyano-Phycocyanin Release from Hydrogels and Ex Vivo Study of Skin Penetration

by Daiva Galinytė, Jurga Bernatoniene, Modestas Žilius, Kristina Rysevaitė-Kyguolienė, Arūnas Savickas, Jūratė Karosienė, Vitalis Briedis, Dainius Haroldas Pauža and Nijolė Savickienė

Pharmaceuticals 2024, 17(9), 1224; https://doi.org/10.3390/ph17091224 (registering DOI) - 17 Sep 2024

Abstract

Background: This study explored the most suitable materials for incorporating cyano-phycocyanin (C-PC) into hydrogels, focusing on maintaining the C-PC’s long-term structural integrity and stabilityNext, the release of C-PC from the hydrogels and its skin penetration were investigated. Methods: A series of 1% (w/w) C-PC hydrogels was prepared using various gelling agents and preservatives. Spectrophotometric measurements compared the amount of C-PC in the hydrogels to the initially added amount. After selecting the most suitable gelling agent and preservative, two C-PC hydrogels, with and without propylene glycol (PG) (Sigma-Aldrich, St. Louis, MO, USA), were produced for further testing. In vitro release studies utilized modified Franz-type diffusion cells, while ex vivo skin-permeation studies employed Bronaugh-type cells and human skin. Confocal laser scanning microscopy analyzed C-PC accumulation in the skin. Results: The findings demonstrated that sodium alginate (Sigma-Aldrich, St. Louis, MO, USA), hydroxyethyl cellulose (HEC) (Sigma-Aldrich, St. Louis, MO, USA), and Soligel^TM (Givaudan, Vernier, Switzerland) are effective biopolymers for formulating hydrogels while maintaining C-PC stability. After 6 h, C-PC release from the hydrogel containing PG was approximately 10% or 728.07 (±19.35) μg/cm², significantly higher than the nearly 7% or 531.44 (±26.81) μg/cm² release from the hydrogel without PG (p < 0.05). The ex vivo qualitative skin-permeation study indicated that PG enhances C-PC penetration into the outermost skin layer. Conclusion: PG’s ability to enhance the release of C-PC from the hydrogel, coupled with its capacity to modify the skin barrier ex vivo, facilitates the penetration of C-PC into the stratum corneum. Full article

(This article belongs to the Special Issue Pharmaceutical Formulation Characterization Design)

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Graphical abstract

Graphical abstract
Full article ">Figure 1
pH of hydrogels and determined concentrations of C-PC in the produced hydrogels with different gelling agents. An asterisk (*) indicates statistically significant differences between the added and determined concentrations of C-PC (p < 0.05), evaluated using a paired-sample t-test. The means and standard deviations are presented. The experiment was repeated three times. Full article ">Figure 2
Determined concentrations of C-PCs in hydrogels with different preservatives. Different letters denote statistically significant differences (p < 0.05) in the C-PC concentrations among hydrogels containing the same gelling agent but different preservatives, as assessed using Bonferroni’s test. An asterisk (*) indicates statistically significant differences (p < 0.05) between the initially added and the determined C-PC concentrations, evaluated using a paired-sample t-test. The means and standard deviations are presented. The experiment was repeated three times. Full article ">Figure 3
The release of C-PC from hydrogels: C-PC PG hydrogel and C-PC hydrogel without PG (control). Different letters indicate statistically significant differences (p < 0.05) determined by independent-samples t-test. Means and standard deviations are presented. The experiment was repeated 3 times. Full article ">Figure 4
Confocal images of human skin autofluorescence (control) and human skin section after treatment with C-PC hydrogel and C-PC PG hydrogel. Scale bar 50 μm. The experiment was repeated 3 times. Full article ">

16 pages, 4776 KiB

Open AccessArticle

Synergistic Antifungal Effect and In Vivo Toxicity of a Monoterpene Isoespintanol Obtained from Oxandra xylopioides Diels

by Orfa Inés Contreras-Martínez, Alberto Angulo-Ortíz, Gilmar Santafé Patiño, Jesus Sierra Martinez, Ricardo Berrio Soto, Joice Margareth de Almeida Rodolpho, Krissia Franco de Godoy, Fernanda de Freitas Aníbal and Bruna Dias de Lima Fragelli

Molecules 2024, 29(18), 4417; https://doi.org/10.3390/molecules29184417 (registering DOI) - 17 Sep 2024

Abstract

Candida sp. infections are a threat to global health, with high morbidity and mortality rates due to drug resistance, especially in immunocompromised people. For this reason, the search for new alternatives is urgent, and in recent years, a combined therapy with natural compounds has been proposed. Considering the biological potential of isoespintanol (ISO) and continuing its study, the objective of this research was to assess the effect of ISO in combination with the antifungals fluconazole (FLZ), amphotericin B (AFB) and caspofungin (CASP) against clinical isolates of C. tropicalis and to evaluate the cytotoxic effect of this compound in the acute phase (days 0 and 14) and chronic phase (days 0, 14, 28, 42, 56, 70 and 84) in female mice (Mus musculus) of the Balb/c lineage. The results show that ISO can potentiate the effect of FLZ, AFB and CASP, showing synergism with these antifungals. An evaluation of the mice via direct observation showed no behavioral changes or variations in weight during treatment; furthermore, an analysis of the cytokines IFN-γ and TNF in plasma, peritoneal cavity lavage (PCL) and bronchoalveolar lavage (BAL) indicated that there was no inflammation process. In addition, histopathological studies of the lungs, liver and kidneys showed no signs of toxicity caused by ISO. This was consistent with an analysis of oxaloacetic transaminases (GOT) and pyruvic transaminases (GPT), which remained in the standard range. These findings indicate that ISO does not have a cytotoxic effect at the doses evaluated, placing it as a monoterpene of interest in the search for compounds with pharmacological potential. Full article

(This article belongs to the Section Natural Products Chemistry)

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22 pages, 2639 KiB

Open AccessReview

Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors in Cancer: Current Use and Future Prospects

by Henry Dickerson, Ahmad Diab and Othman Al Musaimi

Int. J. Mol. Sci. 2024, 25(18), 10008; https://doi.org/10.3390/ijms251810008 (registering DOI) - 17 Sep 2024

Abstract

Tyrosine kinase inhibitors (TKIs) have emerged as a leading targeted cancer therapy, reducing the side effects often seen with non-targeted treatments, especially the damage to healthy cells. To tackle resistance, typically caused by epidermal growth factor receptor (EGFR) mutations, four generations of TKIs have been developed. Each generation has shown improved effectiveness and fewer side effects, resulting in better patient outcomes. For example, patients on gefitinib, a first-generation TKI, experienced a progression-free survival (PFS) of 10 months compared to 5 months with conventional chemotherapy. Second-generation TKI afatinib outperformed erlotinib and extended PFS to 11.1 months compared to 6.9 months with cisplatin. Third-generation TKIs further increased survival to 38.6 months, compared to 31.8 months with first-generation TKIs. This progress demonstrates the ability of newer TKIs to overcome resistance, particularly the T790M mutation, while reducing adverse effects. Ongoing research focuses on overcoming resistance from newer mutations like C797S to further improve patient survival. These developments highlight the significant progress in TKI therapy and the continued effort to refine cancer treatment. Recent research in South Korea shows that third-generation TKIs are ineffective against non-small cell lung cancer (NSCLC) with the C797S mutation. Several trials have started showing promising in vitro and in vivo results, but more trials are needed before clinical approval. This review underscores notable advancements in the field of EGFR TKIs, offering a comprehensive analysis of their mechanisms of action and the progression of various TKI generations in response to resistance. Full article

(This article belongs to the Special Issue Molecular Biology of Protein Kinases: Regulatory Mechanisms, Therapeutic Targets and Cancer Treatments)

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18 pages, 3144 KiB

Open AccessArticle

Theoretical Study of the Effects of Different Coordination Atoms (O/S/N) on Crystal Structure, Stability, and Protein/DNA Binding of Ni(II) Complexes with Pyridoxal-Semi, Thiosemi, and Isothiosemicarbazone Ligand Systems

by Violeta Jevtovic, Aleksandra Rakić, Odeh A. O. Alshammari, Munirah Sulaiman Alhar, Tahani Alenezi, Violeta Rakic and Dušan Dimić

Inorganics 2024, 12(9), 251; https://doi.org/10.3390/inorganics12090251 (registering DOI) - 17 Sep 2024

Abstract

Nickel transition metal complexes have shown various biological activities that depend on the ligands and geometry. In this contribution, six Ni(II) nitrate complexes with pyridoxal-semi, thiosemi, and isothiosemicarbazone ligands were examined using theoretical chemistry methods. The structures of three previously reported complexes ([Ni(PLSC)(H₂O)₃]∙2NO₃⁻, [Ni(PLTSC)₂] ∙2NO₃⁻∙H₂O, and [Ni(PLITSC)(H₂O)₃]∙2NO₃⁻) were investigated based on Hirshfeld surface analysis, and the most important stabilization interactions in the crystal structures were outlined. These structures were optimized at the B3LYP/6-311++G(d,p)(H,C,N,O,(S))/LanL2DZ(Ni) level of theory, and the applicability was checked by comparing theoretical and experimental bond lengths and angles. The same level of theory was applied for the optimization of three additional structures, ([Ni(PLSC)₂]²⁺, [Ni(PLTSC)(H₂O)₃]²⁺, and [Ni(PLITSC)₂]²⁺). The interactions between selected ligands and Ni(II) were examined using the Natural Bond Orbital (NBO) and Quantum Theory of Atoms in Molecules (QTAIM) approaches. Particular emphasis was placed on interactions between oxygen, sulfur, and nitrogen donor atoms and Ni(II). Human Serum Albumin (HSA) and the DNA-binding properties of these complex cations were assessed using molecular docking simulations. The presence of water molecules and various substituents in the thermodynamics of the processes was demonstrated. The results showed significant effects of structural parameters on the stability and reactivity towards important biomolecules. Full article

(This article belongs to the Special Issue Metal Complexes Diversity: Synthesis, Conformations, and Bioactivity)

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Complexation modes of neutral PLSC, PLTSC, and PLITSC ligands. Full article ">Figure 2
Hirshfeld surfaces of different nickel(II) nitrate complexes included in this study. Full article ">Figure 3
Optimized structures (at the B3LYP/6-311++G(d,p)(H,C,N,O,(S)/LanL2DZ(Ni) level of theory) of selected octahedral Ni(II) complexes. Carbon—gray; nitrogen—blue; oxygen—red; sulfur—yellow; nickel—teal; hydrogen atoms have been omitted for clarity. Full article ">Figure 4
Structure of HSA with subdomains: IA in reddish, IB in yellow, IIA in green, IIB in orange, IIIA in lilac, and IIIB in pink. The active positions FA1–FA8 are denoted with the representation of myristic acids (yellow CPK model), commonly bound in the structures. The position of a fluorescent amino acid, Trp214, is depicted as dark green CPK balls, while [Ni(PLSC)2]2+ is presented as purple CPK balls. Full article ">Figure 5
The most important interactions between HSA and [Ni(PLSC)(H2O)3]2+ (left) and [Ni(PLSC)2]2+ (right) complexes, as obtained in the molecular docking simulations. Full article ">Figure 6
The most important interactions between DNA and [Ni(PLSC)(H2O)3]2+ (left) and [Ni(PLSC)2]2+ (right) complexes, as obtained via the molecular docking simulations. Full article ">

8 pages, 422 KiB

Open AccessArticle

Iron Supply of Multivitamins–Multiminerals Commercialized Online by Amazon in Western and Southern Europe: A Labeling Analysis

by Margherita G. M. Mattavelli, Giacomo Piccininni, Gabriel F. Toti, Mario G. Bianchetti, Luca Gabutti, Sebastiano A. G. Lava, Carlo Agostoni, Pietro B. Faré and Gregorio P. Milani

Nutrients 2024, 16(18), 3140; https://doi.org/10.3390/nu16183140 (registering DOI) - 17 Sep 2024

Abstract

Background. In high-income countries, shopping for non-prescription multivitamin–multimineral supplements has tremendously increased. Objective and Methods. The purpose of this labeling analysis is to inform on the daily elemental iron (with or without vitamin C) supply provided by multivitamin–multimineral supplements sold online by Amazon in Western and Southern Europe (amazon.es^®, amazon.de^®, amazon.it^®, and amazon.fr^®). Results. We identified 298 iron-containing multivitamin–multimineral preparations sold by Amazon marketplaces: 153 preparations sourced from amazon.de^®, 68 from amazon.fr^®, 54 from amazon.it^®, and 23 from amazon.es^®. The daily iron dose provided by these preparations was 14 [5–14] mg (median and interquartile range), with no differences among the marketplaces. Approximately 90% (n = 265) of the preparations contained ferrous iron. Moreover, 85% (n = 253) of the preparations were fortified with vitamin C in a dose of 80 [40–100] mg daily. Conclusions. The median supply of iron (about 14 mg) and vitamin C (80 mg) in iron-containing multivitamin–multimineral preparations offered on Amazon platforms in Western and Southern Europe falls below that currently recommended for iron deficiency in review articles, namely 100 mg of iron and 500 mg of vitamin C per day. The iron supply of iron-containing multivitamin–multimineral preparations falls also below the dose of 30–60 mg advocated to prevent iron deficiency in menstruating women. Full article

(This article belongs to the Section Micronutrients and Human Health)

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Graphical abstract

Graphical abstract
Full article ">Figure 1
Daily iron supply provided by 298 iron-containing multivitamin–multimineral preparations sold by amazon.de®, amazon.fr®, amazon.it®, and amazon.es®. The preparations are subdivided into three different groups according to the suggested daily dose of iron, namely 2–9 mg, 10–19 mg, and 20–50 mg daily. Ferrous (Fe2+) iron- and ferric (Fe3+) iron-containing preparations are presented separately. Full article ">

15 pages, 2323 KiB

Open AccessArticle

Novel Approach to Organization of Structured Cobalt-Based Fischer–Tropsch Catalyst

by Andrei Gorshkov, Lilia Sineva, Kirill Gryaznov and Vladimir Mordkovich

Catalysts 2024, 14(9), 628; https://doi.org/10.3390/catal14090628 (registering DOI) - 17 Sep 2024

Abstract

Structured Fischer–Tropsch synthesis catalysts were tested in tubular reactors of industry-standard diameters of 0.5 or 0.75 inches. The structured catalyst bed was manufactured by the obturation of a straight bunch of graphite-based extrudates (D = 1.5 mm, L = 30 mm). A conventional loose bed of granulated catalyst (D = 1.5 mm, L = 3 mm) was tested as a reference. In a 1000–3000 h⁻¹ syngas space velocity range, structured and loose catalyst bed testing showed no significant differences in their main catalytic parameters. Nevertheless, their C₅₊ hydrocarbon group composition was quite different, i.e., the alkene fraction rose from 9 to 23%, while n-alkanes dropped from 81 to 64%. This could be a result of secondary reaction intensification in the conventional loose bed due to its zeolite acid site’s higher availability. Further FTS testing of the structured catalysts in 4000–6000 h⁻¹ manifested distinctive limits in C₅₊ productivity for 0.5 and 0.75 inches of 512 kg C₅₊/(m³ reactor · h) and 362 kg C₅₊/(m³ reactor · h), respectively. This may be explained by limitations in structured bed thermal conductivity. It suggests that the arrangement of extrudates in the structured catalyst can significantly affect the reaction heat and mass transfer conditions and affords new opportunities for group composition control by means of catalyst bed organization. Full article

(This article belongs to the Section Catalysis in Organic and Polymer Chemistry)

23 pages, 3170 KiB

Open AccessArticle

Biochemical Characterization and Disease Control Efficacy of Pleurotus eryngii-Derived Chitosan—An In Vivo Study against Monilinia laxa, the Causal Agent of Plum Brown Rot

by Ippolito Camele, Amira A. Mohamed, Amira A. Ibrahim and Hazem S. Elshafie

Plants 2024, 13(18), 2598; https://doi.org/10.3390/plants13182598 (registering DOI) - 17 Sep 2024

Abstract

Chitin (Ct) is a crucial biopolymer present in fungi, algae, arthropods, and is usually obtained from crustacean shells. Chitosan (Cs) is a derivative from Ct deacetylation, and possesses numerous uses in various agro-industrial fields. Research on fungal-derived Ct and Cs is mostly focused on pharmaceutical uses, however their uses for plant disease control remain less explored. The main objective of the current study is to evaluate the possibility of using chitosan obtained from mushroom Pleurotus eryngii (Cs-Pe) for controlling some phytopathogens compared to commercial chitosan (C.Cs). This study is focused on the following key areas: (i) extracting Ct from P. eryngii mycelium and converting it to Cs through deacetylation, using both bleaching and non-bleaching methods; (ii) conducting a physico-chemical characterization and in vitro evaluation of the antimicrobial activity of the obtained Cs; (iii) performing an in vivo assessment of the phytotoxic and cytotoxic effects of Cs; and (iv) investigating in vivo the impact of the studied chitosan on fruit quality and its biocontrol efficacy against Monilinia laxa infections in plum fruits. Results showed that Cs-Pe, especially the unbleached one, displayed promising in vitro antimicrobial activity against the majority of tested pathogens. Regarding the cytotoxicity, the highest significant increase in cell abnormality percentage was observed in the case of C.Cs compared to Cs-Pe. In the in vivo study, Cs-Pe acted as a protective barrier, lowering and/or preventing moisture loss and firmness of treated plums. The studied Cs-Pe demonstrated notable efficacy against M. laxa which decreased the fruits’ percentage decline. These results strongly suggest that Cs derived from P. eryngii is a potential candidate for increasing plums’ shelf-life. This research shed light on the promising applications of P. eryngii-derived Cs in the agri-food field. Full article

(This article belongs to the Section Plant Protection and Biotic Interactions)

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15 pages, 4909 KiB

Open AccessArticle

Investigating the Effects of Transition Metals and Activated Carbon on Hydrogenation Characteristics of Severely Deformed ZK60 Processed by High-Energy Ball Milling

by Aqeel Abbas, Tzu-Chieh Hsu, Jhe-Yi Lin, Hung-Cheng Ho, Kun-Ming Lin and Hsin-Chih Lin

Materials 2024, 17(18), 4562; https://doi.org/10.3390/ma17184562 (registering DOI) - 17 Sep 2024

Abstract

The synergic effects of activated carbon and transition metals on the hydrogenation characteristics of commercial ZK60 magnesium alloy were investigated. Severe plastic deformation was performed using equal-channel angular pressing with an internal die angle of 120° and preheating at 300 °C. The ZK60 alloy samples were processed for 12 passes using route B_A. The deformed ZK60 alloy powder was blended with activated carbon and different concentrations of transition metals (Ag, Pd, Co, Ti, V, Ti) using high-energy ball milling for 20 h at a speed of 1725 rpm. The amount of hydrogen absorbed and its kinetics were calculated using Sievert’s apparatus at the higher number of cycles at a 300 °C ab/desorption temperature. The microstructure of the powder was analyzed using an X-ray diffractometer and scanning electron microscope. The results indicated that 5 wt% activated carbon presented the maximum hydrogen absorption capacity of 6.2 wt%. The optimal hydrogen absorption capacities were 7.1 wt%, 6.8 wt%, 6.7 wt%, 6.64 wt%, 6.65 wt%, and 7.06 wt% for 0.5 Ag, 0.3 Co, 0.1 Al, 0.5 Pd, 2 Ti, and 0.5 V, respectively. The hydrogen absorption capacities were reduced by 35.21%, 26.47%, 41.79%, 21.68%, 26.31%, and 26.34% after 100 cycles for 5C0.5Ag, 5C0.3Co, 5C0.1Al, 5C0.5Pd, 2Ti, and 5C0.5V, respectively. Hydrogen absorption kinetics were significantly improved so that more than 90% of hydrogen was absorbed within five minutes. Full article

(This article belongs to the Section Energy Materials)

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11 pages, 1144 KiB

Open AccessArticle

Dosimetric Comparison between the HyperArc and Conventional VMAT in Cervical Spine Stereotactic Radiosurgery

by Jeehoon Park, Byungdo Park and Jeongho Kim

J. Clin. Med. 2024, 13(18), 5497; https://doi.org/10.3390/jcm13185497 (registering DOI) - 17 Sep 2024

Abstract

Background: This research aims to evaluate the usability of the HyperArc (HA) technique in stereotactic radiosurgery for cervical spine metastasis by comparing the dosimetry of the target and organs at risk, specifically the spinal cord, between HA and VMAT and conventional volumetric modulated arc therapy (VMAT). Methods: A RANDO^® phantom and QFix Encompass^TM and support system were used to simulate three target types (A, B, and C) based on RTOG0631 guidelines. Treatment plans included one VMAT and two HyperArc techniques with different SRS NTO values (100 and 250). Dosimetric parameters such as conformity index (CI), homogeneity index (HI), R₅₀, and spinal cord sparing were analyzed. Gamma analysis was performed using portal dosimetry to validate the dose delivery accuracy. Results: HyperArc plans demonstrated higher conformity, sharper dose fall-off, and improved quality assurance (QA) results compared to VMAT plans. HA with SRS NTO 250 showed even better results in terms of conformity, dose fall-off, and spinal cord dose reduction (V₁₀ and D_max) compared to HA with SRS NTO 100. Although the mean gamma passing rates were slightly lower, all plans achieved rates above 95%. Conclusion: The findings suggest that HA provides superior dosimetric benefits over VMAT and could be effectively utilized for cervical spine radiation therapy. Full article

(This article belongs to the Topic Innovative Radiation Therapies)

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Target delineation for Types A, B, and C. Full article ">Figure 2
Isodose curve for (a) HA (SRS NTO 250), (b) HA (SRS NTO 100), (c) VMAT (NTO 100), and (d) DVH. Full article ">Figure 3
Dosimetric results for the target and spinal cord. The asterisks and circles represent outlier values, while the numbers denote the sample numbers. Full article ">

17 pages, 4052 KiB

Open AccessArticle

Microplastics Can Inhibit Organic Carbon Mineralization by Influencing Soil Aggregate Distribution and Microbial Community Structure in Cultivated Soil: Evidence from a One-Year Pot Experiment

by Zonghai Chen, Quan Wan, Pengyu Zhou, Haochen Li, Yige Liu, Ying Lu and Bo Li

Agronomy 2024, 14(9), 2114; https://doi.org/10.3390/agronomy14092114 (registering DOI) - 17 Sep 2024

Abstract

Microplastics (MPs) pollution has become a global pollution problem, potentially affecting soil carbon cycling and structure stability in agricultural systems. However, the effects of MPs pollution on soil organic carbon fractions/transformation and soil aggregate stability remain unknown. Thus, a combination of one-year pot and short-term mineralized incubation experiments that involved a reference (CK, with no MPs), different concentrations (0.1, 1, and 2 w/w % polyethylene (PE)), and types (0.1 w/w % PE, polypropylene (PP), and polyvinyl chloride (PVC)) of MPs were carried out to investigate the effects on the soil aggregate stability and organic carbon mineralization after one year of adding MPs. The results showed that the size distribution of the soil partial aggregates varied significantly as affected by the MP concentration and type (p ˂ 0.05). Compared with 0.1% PE, significant increases in the MWD (mean weight diameter) and GMD (geometric mean diameter) of 2% PE of 27.22% and 32.73%, respectively, were detected. In addition, high concentrations (>1%) of PE significantly decreased the dissolved organic carbon (DOC) (p ˂ 0.05), whereas they significantly increased the stable carbon fractions including the particulate organic carbon (POC) and mineral-bound organic carbon (MOC) (p ˂ 0.01). Meanwhile, compared with the CK, both MP types and doses significantly decreased the soil organic carbon mineralization rate (SOCMR) and cumulative mineralization amount (CM) (p ˂ 0.001). Moreover, the MPs significantly increased the total PLFA (phospholipid fatty acid) by 261.9–438.8% (p ˂ 0.01), and the soil pH and total PLFA were the dominant factors that affected the SOCMR as affected by MPs. Thus, a high concentration (>1%) of PE significantly decreased the SOCMR by influencing the soil pH, TN, and macroaggregate (R_>0.25) content and microbial community composition. This study provided evidence of the feedback of MPs pollution on soil C dynamic and aggregates in cultivated soil in South China. Full article

(This article belongs to the Special Issue Net-Zero Emissions for Sustainable Food Production and Land Management)

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Figure 1
Soil physicochemical properties in different MP treatments. Note: (A) represents the pH; (B) represents the content of total nitrogen (TN); (C) represents the content of cation exchange (CEC); (D) represents the content of soil organic carbon (SOC); (E) represents the content of alkaline dissolved nitrogen (AN); (F) represents the content of soil effective phosphorus (AP); CK: treatment without MPs; C: concentration; T: type. MPs’ effects on soil physicochemical properties were analyzed using one-way ANOVA analysis. Different lowercase letters indicate significant differences between different treatments (Duncan’s test, p < 0.05). *: p < 0.05; **: p < 0.01; ***: p < 0.001; n. s.: indicates no significant difference. Full article ">Figure 2
Soil water-stable aggregate stability in different MP treatments. Note: (A) represents the content of large aggregate (R > 0.25); (B) represents the mean weight diameter (MWD); (C) represents the geometric mean diameter (GMD); (D) represents the fractal dimension (FD). Different lowercase letters indicate significant differences between different treatments (Duncan’s test, p < 0.05). C: concentration; T: type. *: p < 0.05; **: p < 0.01; n. s.: indicates no significant difference. Full article ">Figure 3
Soil enzyme activities in different MP treatments. Note: (A) represents the activity of polyphenol oxidase; (B) represents the activity of β-glucosidase; Different lowercase letters indicate significant differences between different treatments (Duncan’s test, p < 0.05). ***: p < 0.001; n. s. indicated no significant. Full article ">Figure 4
Total phospholipid fatty acid (PLFA) contents (A), Gram-positive bacteria PLFA contents (B), Gram-negative bacteria PLFA contents (C) and their PLFA ratios (D), bacteria PLFA contents (E), fungal PLFA contents (F) and their PLFA ratios (G) in different MP treatments. Note: G+: Gram-positive bacteria; G-: Gram-negative bacteria; G+/G−: Gram-positive/Gram-negative bacteria ratio; C: concentration; T: type. Different lowercase letters indicate significant differences between different treatments (Duncan’s test, p < 0.05). *: p < 0.05; **: p < 0.01; ***: p < 0.001. Full article ">Figure 5
Soil organic carbon fractions in different MP treatments. Note: (A) represents the content of particulate organic carbon (POC); (B) represents the content of mineral-associated organic carbon (MOC); (C) represents the content of easily oxidized organic carbon (EOC); (D) represents the content of microbial biomass carbon (MBC); (E) represents the content of hot water-soluble carbon (HWOC); (F) represents the content of dissolved organic carbon (DOC). CK: treatment without MPs. Different lowercase letters indicate significant differences between different treatments (Duncan’s test, p < 0.05). C: concentration; T: type. *: p < 0.05; **: p < 0.01; ***: p < 0.001; n. s.: indicates no significant difference. Full article ">Figure 6
The SOC mineralization rate (A,B) and cumulative mineralization amount (C,D) in different MP treatments. Different lowercase letters indicate significant differences between different treatments (Duncan’s test, p < 0.05). ***: p < 0.001. Full article ">Figure 7
Redundancy analysis (RDA) of the relationships between soil aggregate stability (A), SOC mineralization (B), and soil environment factor in MP treatments. Full article ">

17 pages, 6692 KiB

Open AccessArticle

Detecting the Sigma Phase in Duplex Stainless Steel by Magnetic Noise and First Harmonic Analysis

by João Silva, Edgard Silva, Augusto Sampaio, Rayssa Lins, Josinaldo Leite, Victor Albuquerque Silva and João Manuel R. S. Tavares

Materials 2024, 17(18), 4561; https://doi.org/10.3390/ma17184561 (registering DOI) - 17 Sep 2024

Abstract

Non-destructive electromagnetic tests based on magnetic noise analysis have been developed to study, among others, residual stress, heat treatment outcomes, and harmful microstructures in terms of toughness. When subjected to thermal cycles above 550 °C, duplex stainless steels form an extremely hard and chromium-rich constituent that, if it is superior to 5%, compromises the steel’s corrosion resistance and toughness. In the present work, a study was carried out concerning the interaction of excitation waves with duplex stainless steel. Hence, by analyzing the magnetic noise and variations in the amplitude of the first harmonic of the excitation waves, the detection of the deleterious sigma phase in SAF 2205 steel is studied. To simplify the test, a Hall effect sensor replaced the pick-up coil placed on the opposite surface of the excitation coil. Sinusoidal excitation waves of 5 Hz and 25 Hz with amplitudes ranging from 0.25 V to 9 V were applied to samples with different amounts of the sigma phase, and the microstructures were characterized by scanning electron microscopy. The results show that the best testing condition consists of applying waves with amplitudes from 1 V to 2 V and using the first harmonic amplitude. Thus, the test proved effective for detecting the formation of the deleterious sigma phase and can follow the ability to absorb energy by impact and, thus, the material embrittlement. Full article

(This article belongs to the Special Issue Non-destructive Testing of Materials and Parts: Techniques, Case Studies and Practical Applications)

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