ABSTRACT Photoluminescence (PL) and surface photovoltage spectroscopy applied to nanostructural b... more ABSTRACT Photoluminescence (PL) and surface photovoltage spectroscopy applied to nanostructural bioceramics hydroxyapatite (HAp) allowed to study electron (hole) energy states spectra of HAP and distinguish bulk and surface localized levels. Studied PL excitation spectra allowed obtaining an exact value of the energy band gap in HAP: Eg=3.95eV.This result is consistent with Eg value determined by the contact potential difference (ΔCPD) curves treatment method as Eg=3.94eV. Comparison between ΔCPD and PL spectra indicates that the energy spectra of electron – hole levels studied by two different experimental spectroscopy techniques are very similar. This comparison enables to conclude that all HAp samples have identical electron – hole states structures consisting of five bulk states and one surface state. It is assumed that the deep electron (hole) charged states may be responsible for high bioactivity of the HAp nanoceramics.
Nowadays, three-dimensional (3D) printing technology has been used for rapid prototyping of high ... more Nowadays, three-dimensional (3D) printing technology has been used for rapid prototyping of high quality printed objects. This technology has taken a special place in the field of medicine, and today this technology plays an important role, especially in the field of radiotherapy. Radiotherapy is a main option for treating and management of various types of cancers. Personalized radiotherapy requires precise details. For this reason, it is very important to carry out the exact treatment design at the clinical. 3D printing technology is considered a promising method that can be effective in the treatment of each person in a specific way and as a complementary and promising method to help in integrated treatment and special equipment for each patient. In this chapter, various applications of this technology in radiation therapy have been discussed. This narrative review summarizes the applications of 3D printing technology to develop patient-specific bolus, brachytherapy applicators, ...
Galvenais mērķis - iegūt mezoporainus pārklājumus ir sasniegts. No liela skaita pētīto pārklājumu... more Galvenais mērķis - iegūt mezoporainus pārklājumus ir sasniegts. No liela skaita pētīto pārklājumu trīs iegūti ar poru izmēriem 3-50 nm, kamēr pārējiem paraugiem atkarībā no sola sastāva poru izmēri atrodas plašā diapazonā (no 5 līdz 200 nm)
Sola-gēla metodes pielietojums Fe2O3-TiO2 pārklājumu veidošanā ļauj iegūt materiālus, ko izmantos... more Sola-gēla metodes pielietojums Fe2O3-TiO2 pārklājumu veidošanā ļauj iegūt materiālus, ko izmantostiklveida virsmu dekoratīvai modificēšanai, nanopusvadītāju izveidē, fotokatalizātoru ieguvē u.c
В результате исследований выяснилась возможность использования отходов производства – апретирован... more В результате исследований выяснилась возможность использования отходов производства – апретированных волокон стекла типа Е, для армирования бетона портландцемента. Стекловолокно, покрытое двухслойным золь-гель плёночным покрытием может обеспечить в 2 раза большую (9–12%) химическую устойчивость в щелочной среде, чем волокно неимеющее покрытия (19%)
Šķiedru kompozītmateriāli ar metāla matricu tiek izmantoti jaunākajās inženierzinātņu jomās, jo t... more Šķiedru kompozītmateriāli ar metāla matricu tiek izmantoti jaunākajās inženierzinātņu jomās, jo tiem ir liela mehāniskā izturība, mazs īpatnējais svars un citas paaugtinātas mehāniskās īpašības
Целью данного исследования являлось определение оптимальных условий коагуляции для удаления приро... more Целью данного исследования являлось определение оптимальных условий коагуляции для удаления природных органических веществ (ПОВ) из воды богатой гуминами на станции водоподготовки «Даугава» в г. Риге (Латвия). Оптимизация существующего процесса была проведена в экспериментах Jar путем изменения рН и дозы алюминия, в качестве критэриев оптимизации были такие параметры как: эффективность удаления ПОВ, концентрация остаточного алюминия и количество осадка, образовавшегося после коагуляции. Полученные результаты показали, что удаление ПОВ было 64%, при дозе коагулянта 15 мг Al/л и рН 6. При снижении рН до 5 эффективность удаления ПОВ была выше, но увеличилась концентрация остаточного алюминия. Исследование показало, что существует сильная корреляция между общим органическим углеродом (TOC) и весом полученного осадка, а также между спецефическим поглощения УФ света (SUVA) и весом осадка. Количество гидрофобных фракций было снижено на 61% в образцах речной воды и на 57% в образцах воды по...
The aim of the research was to prepare nanoporous TiO2-ZrO2-SiO2 ceramic via sol-gel technology a... more The aim of the research was to prepare nanoporous TiO2-ZrO2-SiO2 ceramic via sol-gel technology and determine structural, mechanical properties and porosity of ceramic. Nanoporous TiO2-ZrO2-SiO2 ceramic was prepared from titanium, zirconium and silicon alkoxides by sol-gel technology. The nanoporous ceramic samples were prepared by sintering of sol-gel derived xerogel powder that was previously homogenized by milling to particle size between 91–354 nm
Development trends need the necessity for wider use of the local resources and available natural ... more Development trends need the necessity for wider use of the local resources and available natural materials are one of the priorities around the world. Freshwater sapropel is a common material in the water basement of the lakes, but still not sufficiently explored. The main goal of the project to start detailed and systematic research on the medical properties of sapropel to be obtained in Latvia, promote its scientifically based use in balneology, develop new medical procedures and services, and promote development of new exportable products. The results include the survey, sampling depths, and processing, evaluation of external signs, physical, chemical, and biochemical parameters, and evaluation of microbiological indicators. Active components from the sapropel samples extracted using the alkaline method. Sapropel extracts were characterized by organic carbon content, humic and fulvic acid concentrations, total phenolic content, trace metal and pesticide concentrations, total anti...
International Journal of Environmental Research and Public Health, 2022
Considering the multitudes of people who spend their time working indoors in public premises and ... more Considering the multitudes of people who spend their time working indoors in public premises and workplaces, it is worth knowing what their level of exposure is to natural radioactive radon gas, the second most widespread and dangerous carcinogen for lung cancer development after cigarette smoking. This state-level study covered most of the territory of Latvia and conducted 941 radon measurements with Radtrack2, placed for 4–6 months in the premises of public companies, educational institutions, medical care institutions, etc. The study found that 94.7% of samples did not exceed the national permissible limit (200 Bq/m3), the level at which preventive measures should be initiated. The median value of average specific radioactivity of radon in these premises was 48 Bq/m3 (Q1 and Q3 being 27 and 85 Bq/m3), which is below the average of the European region. Slightly higher concentrations were observed in well-insulated premises with plastic windows and poorer air exchange, mostly in sc...
While many people work remotely during the pandemic, three-dimensional (3D) printers are working ... more While many people work remotely during the pandemic, three-dimensional (3D) printers are working to ensure the medical personnel and general public with the necessary specific materials. Ease of use, low cost, fast prototyping, and a wide range of materials are the advantages of 3D technology that can quickly adapt to specific needs in different application areas and result in increased popularity. The aim was to analyse the concentrations of particulate matter (PM) and volatile organic compounds (VOCs) emitted in 3D printing zone where printers are located throughout the room around the perimeter and where orthopaedics and designers develop models during their full shift. The average ultrafine particles (UFP) concentration level fluctuates from 4×103 to 26×103 particles/cm3 that exceed the background level (<3×103 particles/cm3) during 8 h-shift. Microclimate was evaluated as unsatisfied regarding permissible values for air quality at workplaces: air temperature exceeds permissi...
For many years the printers have been essential part of our offices and exposures from various pr... more For many years the printers have been essential part of our offices and exposures from various printing technologies have been widely researched. The main objective of this study was to compare emitted number and mass of fine particles from laser printers and new Micro Piezo technology ink jet printers during the printing process and one hour afterwards as these emissions have potential for negative health effects. Air samples were taken with the particle size spectrometer for real-time ELPI+, Dekati (air flow rate 10 l/min). Measurements were taken ~0.5 m from the printers: one hour before the test, during printing and one hour afterwards. Similar class black&white (b/w) and colour printer of each technology were tested. Each printer performed a 10-page and a 100page test according to ECMA 328-1 Standard [1]. During laser printer tests from 8324 to 19943 pt/cm3 fine particles were determined on printing phase from b/w and colour printers. Ink jet (Micro Piezo) printers produced les...
ABSTRACT Photoluminescence (PL) and surface photovoltage spectroscopy applied to nanostructural b... more ABSTRACT Photoluminescence (PL) and surface photovoltage spectroscopy applied to nanostructural bioceramics hydroxyapatite (HAp) allowed to study electron (hole) energy states spectra of HAP and distinguish bulk and surface localized levels. Studied PL excitation spectra allowed obtaining an exact value of the energy band gap in HAP: Eg=3.95eV.This result is consistent with Eg value determined by the contact potential difference (ΔCPD) curves treatment method as Eg=3.94eV. Comparison between ΔCPD and PL spectra indicates that the energy spectra of electron – hole levels studied by two different experimental spectroscopy techniques are very similar. This comparison enables to conclude that all HAp samples have identical electron – hole states structures consisting of five bulk states and one surface state. It is assumed that the deep electron (hole) charged states may be responsible for high bioactivity of the HAp nanoceramics.
Nowadays, three-dimensional (3D) printing technology has been used for rapid prototyping of high ... more Nowadays, three-dimensional (3D) printing technology has been used for rapid prototyping of high quality printed objects. This technology has taken a special place in the field of medicine, and today this technology plays an important role, especially in the field of radiotherapy. Radiotherapy is a main option for treating and management of various types of cancers. Personalized radiotherapy requires precise details. For this reason, it is very important to carry out the exact treatment design at the clinical. 3D printing technology is considered a promising method that can be effective in the treatment of each person in a specific way and as a complementary and promising method to help in integrated treatment and special equipment for each patient. In this chapter, various applications of this technology in radiation therapy have been discussed. This narrative review summarizes the applications of 3D printing technology to develop patient-specific bolus, brachytherapy applicators, ...
Galvenais mērķis - iegūt mezoporainus pārklājumus ir sasniegts. No liela skaita pētīto pārklājumu... more Galvenais mērķis - iegūt mezoporainus pārklājumus ir sasniegts. No liela skaita pētīto pārklājumu trīs iegūti ar poru izmēriem 3-50 nm, kamēr pārējiem paraugiem atkarībā no sola sastāva poru izmēri atrodas plašā diapazonā (no 5 līdz 200 nm)
Sola-gēla metodes pielietojums Fe2O3-TiO2 pārklājumu veidošanā ļauj iegūt materiālus, ko izmantos... more Sola-gēla metodes pielietojums Fe2O3-TiO2 pārklājumu veidošanā ļauj iegūt materiālus, ko izmantostiklveida virsmu dekoratīvai modificēšanai, nanopusvadītāju izveidē, fotokatalizātoru ieguvē u.c
В результате исследований выяснилась возможность использования отходов производства – апретирован... more В результате исследований выяснилась возможность использования отходов производства – апретированных волокон стекла типа Е, для армирования бетона портландцемента. Стекловолокно, покрытое двухслойным золь-гель плёночным покрытием может обеспечить в 2 раза большую (9–12%) химическую устойчивость в щелочной среде, чем волокно неимеющее покрытия (19%)
Šķiedru kompozītmateriāli ar metāla matricu tiek izmantoti jaunākajās inženierzinātņu jomās, jo t... more Šķiedru kompozītmateriāli ar metāla matricu tiek izmantoti jaunākajās inženierzinātņu jomās, jo tiem ir liela mehāniskā izturība, mazs īpatnējais svars un citas paaugtinātas mehāniskās īpašības
Целью данного исследования являлось определение оптимальных условий коагуляции для удаления приро... more Целью данного исследования являлось определение оптимальных условий коагуляции для удаления природных органических веществ (ПОВ) из воды богатой гуминами на станции водоподготовки «Даугава» в г. Риге (Латвия). Оптимизация существующего процесса была проведена в экспериментах Jar путем изменения рН и дозы алюминия, в качестве критэриев оптимизации были такие параметры как: эффективность удаления ПОВ, концентрация остаточного алюминия и количество осадка, образовавшегося после коагуляции. Полученные результаты показали, что удаление ПОВ было 64%, при дозе коагулянта 15 мг Al/л и рН 6. При снижении рН до 5 эффективность удаления ПОВ была выше, но увеличилась концентрация остаточного алюминия. Исследование показало, что существует сильная корреляция между общим органическим углеродом (TOC) и весом полученного осадка, а также между спецефическим поглощения УФ света (SUVA) и весом осадка. Количество гидрофобных фракций было снижено на 61% в образцах речной воды и на 57% в образцах воды по...
The aim of the research was to prepare nanoporous TiO2-ZrO2-SiO2 ceramic via sol-gel technology a... more The aim of the research was to prepare nanoporous TiO2-ZrO2-SiO2 ceramic via sol-gel technology and determine structural, mechanical properties and porosity of ceramic. Nanoporous TiO2-ZrO2-SiO2 ceramic was prepared from titanium, zirconium and silicon alkoxides by sol-gel technology. The nanoporous ceramic samples were prepared by sintering of sol-gel derived xerogel powder that was previously homogenized by milling to particle size between 91–354 nm
Development trends need the necessity for wider use of the local resources and available natural ... more Development trends need the necessity for wider use of the local resources and available natural materials are one of the priorities around the world. Freshwater sapropel is a common material in the water basement of the lakes, but still not sufficiently explored. The main goal of the project to start detailed and systematic research on the medical properties of sapropel to be obtained in Latvia, promote its scientifically based use in balneology, develop new medical procedures and services, and promote development of new exportable products. The results include the survey, sampling depths, and processing, evaluation of external signs, physical, chemical, and biochemical parameters, and evaluation of microbiological indicators. Active components from the sapropel samples extracted using the alkaline method. Sapropel extracts were characterized by organic carbon content, humic and fulvic acid concentrations, total phenolic content, trace metal and pesticide concentrations, total anti...
International Journal of Environmental Research and Public Health, 2022
Considering the multitudes of people who spend their time working indoors in public premises and ... more Considering the multitudes of people who spend their time working indoors in public premises and workplaces, it is worth knowing what their level of exposure is to natural radioactive radon gas, the second most widespread and dangerous carcinogen for lung cancer development after cigarette smoking. This state-level study covered most of the territory of Latvia and conducted 941 radon measurements with Radtrack2, placed for 4–6 months in the premises of public companies, educational institutions, medical care institutions, etc. The study found that 94.7% of samples did not exceed the national permissible limit (200 Bq/m3), the level at which preventive measures should be initiated. The median value of average specific radioactivity of radon in these premises was 48 Bq/m3 (Q1 and Q3 being 27 and 85 Bq/m3), which is below the average of the European region. Slightly higher concentrations were observed in well-insulated premises with plastic windows and poorer air exchange, mostly in sc...
While many people work remotely during the pandemic, three-dimensional (3D) printers are working ... more While many people work remotely during the pandemic, three-dimensional (3D) printers are working to ensure the medical personnel and general public with the necessary specific materials. Ease of use, low cost, fast prototyping, and a wide range of materials are the advantages of 3D technology that can quickly adapt to specific needs in different application areas and result in increased popularity. The aim was to analyse the concentrations of particulate matter (PM) and volatile organic compounds (VOCs) emitted in 3D printing zone where printers are located throughout the room around the perimeter and where orthopaedics and designers develop models during their full shift. The average ultrafine particles (UFP) concentration level fluctuates from 4×103 to 26×103 particles/cm3 that exceed the background level (<3×103 particles/cm3) during 8 h-shift. Microclimate was evaluated as unsatisfied regarding permissible values for air quality at workplaces: air temperature exceeds permissi...
For many years the printers have been essential part of our offices and exposures from various pr... more For many years the printers have been essential part of our offices and exposures from various printing technologies have been widely researched. The main objective of this study was to compare emitted number and mass of fine particles from laser printers and new Micro Piezo technology ink jet printers during the printing process and one hour afterwards as these emissions have potential for negative health effects. Air samples were taken with the particle size spectrometer for real-time ELPI+, Dekati (air flow rate 10 l/min). Measurements were taken ~0.5 m from the printers: one hour before the test, during printing and one hour afterwards. Similar class black&white (b/w) and colour printer of each technology were tested. Each printer performed a 10-page and a 100page test according to ECMA 328-1 Standard [1]. During laser printer tests from 8324 to 19943 pt/cm3 fine particles were determined on printing phase from b/w and colour printers. Ink jet (Micro Piezo) printers produced les...
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