Plastics: physical-and-mechanical properties and biodegradable potential

Introduction. Processing agricultural waste into plant biodegradable plastics is a promising way for its recycling. This work featured the main physical-and-mechanical properties of plant plastics without adhesive substances obtained from millet husk and wheat husk and wood plastic obtained from sawdust, as well as their biodegradation potential. Study objects and methods. Objects of the study were plastics without adhesives based on wood sawdust, millet husk, and wheat husk. Results and discussion. We analyzed of the physical-and-mechanical parameters of the plant plastic based on millet husk, wheat husk, as well as wood plastic based on sawdust. The analysis showed that, in general, the sbeiigth characteristics of the wood plastics were higher than those of the plastics based on millet husk, especially flexural strength. Thus, the average value of the density of the wood plastic exceeded that of the plant plastic from millet husk by 10%, hardness by 40%, compression elasticity modulus by 50%, and flexural modulus by 3.9 times. It was found that wood and plant plastics obtained from sawdust, millet husk, and wheat husk without adhesives had a high biodegradation potential. Conclusion. The plastics obtained can be used as an insulating, building, and decorative material in the steppe regions experiencing a shortage of wood and wood powder

Size effects in chlorine doped PbSe thin films

The possibility of obtaining strongly degenerate (≈ 3·10²⁰ сm⁻³) PbSe thin films (d = 5 – 220 nm) with n-type conductivity by thermal evaporation in vacuum of PbSe crystals doped with PbCl₂, with subsequent condensation onto (001) KCl substrates was established. It was shown that the films had high homogeneity degree, no grain structure was observed. The thickness dependences of thermoelectric properties (the Seebeck coefficient S, the Hall coefficient RH and the electric conductivity σ) of thin films were obtained. In the thickness range d ≈ 5 ÷ 30 nm, oscillation properties were observed with growth of d that are attributable to electron gas quantization. The calculation of S(d) dependence on the assumption of size quantization with regard to contribution of several subbands and the thickness dependence of the Fermi energy was shown to be in agreement with the experimental data. In the region of d > 30 nm there was growth of S and σ with thickness, which is attributable to manifestation of classical size effect and interpreted in the framework of Fuchs-Sondheimer and Mayer theories

Biodegradation of acetyl cellulose etrols

This work aimed to study the biodegradation dynamics of plasticized cellulose acetate samples (etrols) with different content of plasticizers. Isophthalic acid dimethyl ester and orthophosphoric acid tributyl ester were used as plasticizers. The targets of the study also included assessing the effect of the plasticizers' content on the degradation rate. The biodegradability of plasticized cellulose acetate samples was assessed by measuring the weight loss after exposure to active soil. For the experiment, an active soil of the following composition was prepared: garden soil - 89 vol. %, distilled water - 10 vol. %, microbiological preparation "Tamir"- 1 vol. %. All etrols samples showed a tendency to decomposition in active soil. The rate of sample degradation varied significantly. The highest degradation rate in active soil was shown by a sample containing 16 wt. % tributyl phosphate and 22 wt. % dimethyl isophthalate, as good as ertols sample containing 8 wt. % tributyl phosphate and 14 wt. % dimethyl isophthalate. The expected decomposition time of these samples in the active soil for 90% is 599 and 732 days, respectively. Changing of dimethyl isophthalate content did not affect the degradation rate. Withal the content of tributyl phosphate in the etrols induced a significant effect on the samples' weight loss. The consequence of the plasticizers' content on the weight loss rate for 145 days of exposure in the active soil is described by the equation y=-4.76+1.25•Z 1+1.49•Z2-0.04•Z 12-0.086•Z22+0.000141 where Z1 is the content of dimethyl isophthalate, Z2 is the content of tributyl phosphate. © Published under licence by IOP Publishing Ltd

РАДИОНУКЛИДНАЯ ОЦЕНКА АЛЬВЕОЛЯРНО КАПИЛЛЯРНОЙ ПРОНИЦАЕМОСТИ ДЛЯ ДИФФЕРЕНЦИАЛЬНОЙ ДИАГНОСТИКИ ЛЕГОЧНОГО ИНФИЛЬТРАТА

Summary.Ventilation scintigraphy of the lungs with analysis of alveolar-capillary permeability (ACP) was performed in patients with confirmed diagnoses of community-acquired pneumonia (CAP, n = 40), infiltrative pulmonary tuberculosis (IPT, n = 20), distal pulmonary embolism (DPE, n = 11),peripheral lung carcinoma (PLC, n = 17), and in 22 healthy volunteers. ACP values were higher in affected and intact lungs in patients with CAP at 10 and 30 min of the investigation vs those with DPE and were higher at 30 min in the affected lung in patients with CAP compared to patients with IPT. Comparison of ACPs in DPE and IPT patients revealed the ACP reduction in affected and intact lungs of DPE patients at 30 min of the investigation. PLC patients demonstrated the ACP reduction in affected lung compared to contralateral lung. Therefore, ACP gave additional information for differential diagnosis of CAP, IPT, DPE and PLCРезюме. У 88 пациентов с верифицированными диагнозами: внебольничная пневмония (ВП) – 40, инфильтративный туберкулез легких(ИТЛ) – 20, тромбоэмболия дистальных ветвей легочной артерии (ТДВЛА) – 11, периферический рак легких (ПРЛ) – 17, а также у 22 здоровых добровольцев проведена вентиляционная пульмоносцинтиграфия с анализом альвеолярно-капиллярной проницаемости (АКП). При ВП, в отличие от ТДВЛА и ИТЛ, АКП была выше на 10-й и 30-й мин исследования в пораженном и интактном легких по сравнению с ТДВЛА и на 30-й мин исследования – в пораженном легком по сравнению с ИТЛ. Сопоставление значений АКП у больных ТДВЛА и ИТЛ показало снижение АКП на 30-й мин исследования у больных ТДВЛА в пораженном и интактном легких. У пациентов с ПРЛ регистрировалось снижение АКП на стороне поражения по сравнению с контралатеральным легким. Таким образом, оценка АКП позволяет расширить возможности дифференциальной диагностики ВП, ИТЛ, ТДВЛА и ПРЛ

Усинские тувинцы в XXI веке

A small group of nomadic Tuvans have long lived in the south of Krasnoyarsk Krai, on the border with Tuva. They were considered non-residents and, thus, were not taken into account by statistics until Tuva became a part of the USSR. By the 1970-s they lived around Verkhneusinskoe and Nizhneusinskoe, Russian settlements, were engaged in cattle breeding. Their separate residence contributed to the preservation of the Tuvan language and culture. In 1990-s almost all the Tuvans moved to towns due to the cattle breeding reduction. Their contacts with the Russians also increased largely. The number of mixed marriages grew, and language and cultural assimilation started. Migrations resulted in the Tuvans’ depopulation from 476 to 367 people. In the future a further growth of assimilation processes can be expected as the children predominantly speak RussianИздавна на юге Красноярского края, на границе с Тувой, проживала небольшая группа кочевых тувинцев. До вхождения Тувы в состав СССР они считались иностранцами и не учитывались статистикой. К 1970-м годам тувинцы проживали вокруг русских поселков Верхнеусинское и Нижнеусинское, занимаясь скотоводством. Раздельное проживание способствовало сохранению тувинского языка и культуры. В 1990-е годы в связи с сокращением скотоводства почти все тувинцы переселились в поселки и контакты с русскими резко активизировались. Возросло число национально-смешанных браков, началась языковая и культурная ассимиляция. Миграции привели к сокращению численности тувинцев с 476 до 367 человек. В перспективе можно ожидать дальнейшего развития ассимиляционных процессов, так как в детской возрастной группе уже преобладает русский язы

Modeling of wood-polymer composites properties

The article describes the issues of the formation of experimental-statistical math models of properties of wood-polymer composites with thermoplastic polymer matrix and evaluation of their adequacy, as well as the examination of properties of the composite with polypropylene polymer matrix and split sawdust used as filling compound. In addition, mass contents of filling compound and lubricant in the composite structure were taken as technological factors affecting the material properties. The research results are an evaluation of the influence of technological factors on the properties of wood-polymer composites. © 2022 Author(s)

Обзор влияния химического состава компонентов на скорость биоразложения и физико-механические свойства полимерных композитов с лигноцеллюлозными наполнителями

The results of TPLC scientific research, practical experience of their preparation, and application as of 2016 are presented in eight volumes of the “Handbook of Composites from Renewable Materials” (2017, John Wiley & Sons, Inc.). This article provides an analysis of books and articles with open access to the Science Direct (Elsevier) database for the period 2017-2020 to assess the biodegradation rate and physical and mechanical properties of polymer composites with lignocellulosic fillers. The production and use of polymer composites with a thermoplastic polymer matrix and lignocellulosic fillers (TPLC) have significant ecological and economic prospects since waste biomass from forests, agriculture, and polymers obtained from petroleum raw materials can be used for their production. However, depending on the TPLC application area, there are opposite requirements for the biodegradation rate. For the use in construction and medicine materials and products must have a minimum biodegradation rate. Materials and products for single-use packaging must have the necessary biodegradability potential and have an adjusted biodegradation rate in soil, water, compost environment. Research results show that the properties of TPLC can be significantly influenced not only by the physical but also by the chemical structure of all components of these composites. The chemical properties of polymers, fillers, additives for various purposes can affect their industrial production efficiency. © 2021 The Authors. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/

Late Glacial and Holocene changes in vegetation cover and climate in southern Siberia derived from a 15 kyr long pollen record from Lake Kotokel

In this study a radiocarbon-dated pollen record from Lake Kotokel (52°47´ N, 108°07´ E, 458 m a.s.l.) located in southern Siberia east of Lake Baikal was used to derive quantitative characteristics of regional vegetation and climate from about 15 kyr BP (1 kyr=1000 cal. yr) until today. Quantitative reconstruction of the late glacial vegetation and climate dynamics suggests that open steppe and tundra communities predominated in the study area prior to ca. 13.5 kyr BP and again during the Younger Dryas interval, between 12.8 and 11.6 kyr BP. The pollen-based climate reconstruction suggests lower-than-present mean January (~−38°C) and July (~12°C) temperatures and annual precipitation (~270–300 mm) values during these time intervals. Boreal woodland replaced the primarily open landscape around Kotokel three times at about 14.8–14.7 kyr BP, during the Allerød Interstadial between 13.3–12.8 kyr BP and with the onset of the Holocene interglacial between 11.5 and 10.5 kyr BP, presumably in response to a noticeable increase in precipitation, and in July and January temperatures. The maximal spread of the boreal forest (taiga) communities in the region is associated with a warmer and wetter-than-present climate (<i>T<sub>w</sub></i>~17–18°C, <i>T<sub>c</sub></i>~−19°C, <i>P</i><sub>ann</sub>~500–550 mm) that occurred ca. 10.8–7.3 kyr BP. During this time interval woody vegetation covered more than 50% of the area within a 21×21 km window around the lake. The pollen-based best modern analogue reconstruction suggests a decrease in woody cover percentages and in all climatic variables about 7–6.5 kyr BP. Our results demonstrate a gradual decrease in precipitation and mean January temperature towards their present-day values in the region around Lake Kotokel since that time

Усинские тувинцы в XXI веке

A small group of nomadic Tuvans have long lived in the south of Krasnoyarsk Krai, on the border with Tuva. They were considered non-residents and, thus, were not taken into account by statistics until Tuva became a part of the USSR. By the 1970-s they lived around Verkhneusinskoe and Nizhneusinskoe, Russian settlements, were engaged in cattle breeding. Their separate residence contributed to the preservation of the Tuvan language and culture. In 1990-s almost all the Tuvans moved to towns due to the cattle breeding reduction. Their contacts with the Russians also increased largely. The number of mixed marriages grew, and language and cultural assimilation started. Migrations resulted in the Tuvans’ depopulation from 476 to 367 people. In the future a further growth of assimilation processes can be expected as the children predominantly speak RussianИздавна на юге Красноярского края, на границе с Тувой, проживала небольшая группа кочевых тувинцев. До вхождения Тувы в состав СССР они считались иностранцами и не учитывались статистикой. К 1970-м годам тувинцы проживали вокруг русских поселков Верхнеусинское и Нижнеусинское, занимаясь скотоводством. Раздельное проживание способствовало сохранению тувинского языка и культуры. В 1990-е годы в связи с сокращением скотоводства почти все тувинцы переселились в поселки и контакты с русскими резко активизировались. Возросло число национально-смешанных браков, началась языковая и культурная ассимиляция. Миграции привели к сокращению численности тувинцев с 476 до 367 человек. В перспективе можно ожидать дальнейшего развития ассимиляционных процессов, так как в детской возрастной группе уже преобладает русский язы