Polystyrene-based nanocomposites with different fillers: fabrication and mechanical properties

The paper presents a comprehensive analysis of elastic properties of polystyrene-based nanocomposites filled with different types of inclusions: small spherical particles (SiO2 and Al2O3), alumosilicates (montmorillonite, halloysite natural tubules and Mica) and carbon nanofillers (carbon black and multi-walled carbon nanotubes). Composites were fabricated by melt technology. The analysis of composite melts showed that the introduction of Montmorillonite, Multi-walled carbon nanotubes, and Al2O3 particles provided an increase in melt viscosity by an average of 2 to 5 orders of magnitude over the pure polystyrene. Block samples of composites with different filler concentrations were prepared, and their linear and nonlinear elastic properties were studied. The introduction of more rigid particles led to a more profound increase in the elastic modulus of the composite, with the highest rise of about 80% obtained with carbon fillers. Carbon black particles provided also an enhanced strength at break of about 20% higher than that of pure polystyrene. The nonlinear elastic moduli of composites were shown to be more sensitive to addition of filler particles to the polymer matrix than the linear ones. The nonlinearity coefficient $\beta$ comprising the combination of linear and nonlinear elastic moduli of a material demonstrated considerable changes correlating with changes of the Young's modulus. The absolute value of $\beta$ showed rise in 1.5-1.6 times in the CB- and HNT-containing composites as compared to that of pure PS. The changes in nonlinear elasticity of fabricated composites were compared with measurements of the parameters of bulk nonlinear strain waves in them. Variations of wave velocity and decay decrement correlated with observed enhancement of materials nonlinearity

High-Q bismuth silicate nonlinear glass microsphere resonators

The fabrication and characterization of a bismuth-silicate glass microsphere resonator has been demonstrated. At wavelengths near 1550 nm, high-modes can be efficiently excited in a 179 µm diameter bismuth-silicate glass microsphere via evanescent coupling using a tapered silica fiber with a waist diameter of circa 2 µm. Resonances with Q-factors as high as were observed. The dependence of the spectral response on variations in the input power level was studied in detail to gain an insight into power-dependent thermal resonance shifts. Because of their high nonlinearity and high- factors, bismuth-silicate glass microspheres offer the potential for robustly assembled fully integrated all-optical switching devices

МЕТОДИ ВДОСКОНАЛЕННЯ ВЗАЄМОДІЇ СУБ’ЄКТІВ ЕКОНОМІЧНОЇ СИСТЕМИ ВОДОКОРИСТУВАННЯ

This article analyses the system of water resources users due to the available parameters. The problems of the cooperation between the elements of the system and influence of the deficiencies in their coworkon the rational resources use system were investigated. Methods to improve the indicators of rational water resources use by using the mechanisms and their combinations for the better users cooperation have been proposed.Проанализирована система субъектов водопользования по доступным параметрам. Исследована проблематика взаимодействия субъектов и влияние недостатков в их взаимодействии на систему рационального водопользования. Предложены методы учета доступных механизмов и их комбинаций по поводу взаимодействия субъектов системы для улучшения показателей рационального водопользования.Проаналізовано систему суб’єктів водокористування за доступними параметрами. Досліджено проблематику взаємодії суб’єктів та вплив недоліків у взаємодії водокористувачів на систему раціонального водокористування. Запропоновані методи врахування доступних механізмів та їх комбінацій щодо взаємодії суб’єктів системи для покращання показників раціонального водокористування

ЕКОНОМІЧНІ ОСНОВИ ВПРОВАДЖЕННЯ ПОВТОРНОГО ВОДОКОРИСТУВАННЯ ВІДПОВІДНО ДО КОНЦЕПЦІЇ «ВІРТУАЛЬНОЇ» ВОДИ ТА «ВОДНОГО СЛІДУ»

This article gives a characteristic of the concept of the secondary water resources use due to industrial needs. The problematic of involvement ofwater for the secondary use is being described. The methods of therationalization of water resources use were proposed, basing on theconcept of virtual water and water step as a tool for defining and analyzingthe current situation in the regional water resources use.В данной статье охарактеризована концепция повторного использования воды в промышленных нуждах, описана проблематика внедренияводы для повторного водопользования. Предложены методы рационализации водопользования на основе концепции виртуальной воды и водного следа как инструмента определения и анализа текущей ситуации водопользования в регионе.Проаналізовано концепцію повторного використання води у промислових потребах. Досліджено проблематику залучення води для повторного використання. Запропоновані методи раціоналізації водокористування на основі концепції «віртуальної» води та водного сліду як інструменту визначення та аналізу поточної ситуації водокористування у регіоні

An SMS fiber structure based on a chalcogenide multimode fiber

We theoretically and experimentally investigate a singlemode-multimode-singlemode (SMS) structure based on chalcogenide (As2S3) multimode fiber and conventional silica singlemode fibers. The experimental results show a general agreement with the numerical simulation results based on a wide angle-beam propagation method (WA-BPM). The chalcogenide fiber and silica fibers were mechanically spliced and packaged using a UV cured polymer with a low refractive index on a microscope slide. Multimode interference variation was observed by photo-induced refractive index changes resulting from both a localized laser irradiation at a wavelength of 405 nm and a UV lamp. Our result provides a platform for the development of compact, high-optical-quality, and robust photonic nonlinear devices

Nephelometric Method for Determination of Growth Parameters of Chlorella Culture

Nephelometric method for the determination of growth parameters of chlorella culture using a photoelectric colorimeter was described. Use of photoelectric colorimeter for cell counting in suspension requires periodic calibration of meter readings using chlorella standard culture (with a certain cell concentration). Chlorella vulgaris IPPAS С-66, IPPAS С-111 and IPPAS С-2019 strains served as object of research. Density of initial in vitro suspensions (after inoculation) was 0.9 mln cells/ml. Cultivation was carried out during 12 days on a Hoagland medium with a pH of 7 (temperature of 35∘C, illumination of 10 klx). Sample selection for analysis and measurement was carried out daily, three times per day. Based on the obtained data, readings of photoelectric colorimeter KFK-3.01 were calibrated via direct count of chlorella cells quantity in Goryaev’s chamber. Use of calibration curve made it possible to reduce significantly time and error in determination of cell number in suspension cultures. The proposed technique allows counting chlorella cells in the growth and development dynamics with sufficient accuracy, high sensitivity, reproducibility and speed. It can be used for comparative determination of the growth parameters of strains in vitro, standardization of suspension cultures, semi-quantitative determination of chlorella biomass in order to predict the yield of desired product

Experimental Demonstration of Nanolaser with sub-μ\muA Threshold Current

We demonstrate a photonic crystal nanolaser exhibiting an ultra-low threshold of 730 nA at telecom wavelengths. The laser can be directly modulated at 3 GHz at an energy cost of 1 fJ/bit. This is the lowest threshold reported for any laser operating at room temperature and facilitates low-energy on-chip links.Comment: 3 pages with 2 figure

Phenotypic traits differentiating the genetic resources of pea (<i>Pisum sativum</i> L.) by the type of use

The paper presents an analysis of the data obtained for pea accessions from the VIR collection studied at the Adler Experiment Station in the setting of the Krasnodar Territory in 2017–2019. It was for the first time that these accessions were studied for a set of phenotypic traits. The object of the study was a sample of 494 pea accessions originated from 43 countries and 18 regions and territories of the Russian Federation. The work was carried out in compliance with the methodological guidelines developed at VIR. Statistica 13.3 software was employed for statistical data processing. An assessment of four qualitative, 10 quantitative and four phenological traits in the accessions made it possible to differentiate them by the type of use, that is, as dry, forage and garden peas. The varieties differing in the type of use significantly differed by the values of such traits as stem length, number of pods per plant, number of nodes to the first flower, number of flowers in the inflorescence, the maximum number of seeds per pod, pod length, and a narrower pod of forage pea compared to that of dry and garden peas. The average values of these traits were recorded for the peas with different types of use. The maximum difference was noted between garden and forage pea varieties. Dry pea varieties occupied an intermediate position. The complex of phenotypic traits identified determines the differences between three types of pea use, which is important when selecting the initial material for breeding appropriate varieties

Epidemiological and Economic Evaluation of a Pilot Prostate Cancer Screening Program

Background. Prostate cancer (PCa) is the second most commonly diagnosed cancer, and the sixth most common killer among men worldwide (Aubry et al., 2013). This research was motivated by the fact that PCa screening continues to be a controversial topic in the Kazakh medical community. This study aimed at description of how newly diagnosed PCa patients are managed in Pavlodar region of the Kazakhstan Republic and at presentation of a budget impact analysis (BIA) for PCa screening program. Also, we aimed to provide a comparative analysis of pricing system on medical services applied in both private and public healthcare sectors of the Kazakhstan Republic. Methods. New cases of PCa have been retrospectively analyzed for the period from January 2013 to December 2017 based on the information obtained from information system "Policlinic" maintained by the Pavlodar regional branch of the Republican Center for Electronic Health and from Cancer Registry of Pavlodar Regional Oncology Center. All data were analyzed with the help of SPSS 20.0 software. Results. The mean age of PCa patients was 68.34 years (SD = 8.559). The government of Kazakhstan invested 20,437,000 KZT (Kazakhstani tenge) in 2017 equivalently 61,188 USD - to fund a pilot study for examination of 9638 men. From 2013 to 2017, out of 49,334 men residing in Pavlodar region of Kazakhstan 1,248 men were diagnosed with prostate diseases, including 130 PCa cases. The PCa detection rate was equal to two cases per month. Only 22.8% of all PCa cases identified in the region within specified time period were revealed as a result of the government-funded PCa screening program. The average prostate cancer detection rate among the target group of Pavlodar region within the period of 5 years was equal to 0.23%. Conclusion. Based on the fact that the PCa screening program failed to enable adequate detection of new PCa cases, we would not recommend to continue this type of screening unless it is undergone careful revision and replanning