Effect of Carbon Nanotube Aqueous Dispersion Quality on Mechanical Properties of Cement Composite

An effect of the quality of carbon nanotube (CNT) dispersions added to cement on paste mechanical properties has been studied. High-quality dispersions of few-walled CNT (FWCNTs) were produced in two steps. First, FWCNTs were functionalized in a mixture of nitric and sulfuric acids (70 wt.% and 96 wt.%, resp.) at 80 ∘C . Second, functionalized FWCNTs were washed out by acetone to remove carboxylated carbonaceous fragments (CCFs) formed during CNT oxidation. Mechanical test results showed 2-fold increase in the compressive strength of the cement paste prepared from the dispersion of acetone-washed functionalized FWCNTs, which is believed to occur due to the chemical interaction between cement matrix and functional groups (–COOH and –OH). Utilisation of unwashed FWCNTs led to a marginal improvement of mechanical properties of the cement pastes, whereas surfactant-treated functionalized FWCNT dispersions only worsened the mechanical properties.Peer reviewe

Carbon Nanotube/Nanofibers and Graphite Hybrids for Li-Ion Battery Application

To improve the electrical conductivity of negative electrodes of lithium ion batteries, we applied a direct CVD synthesis of carbon nanomaterials on the surface of graphite particles. To prepare a catalyst, two alternative approaches were utilized: colloidal nanoparticles (NPs) and metal (Ni and Co) nitrate salt precursors deposited on the graphite surface. Both colloidal and precursor systems allowed us to produce carbon nanofibers (CNFs) on the graphite surface with high coverage under the optimum CVD conditions. Electrical measurements revealed that the resistivity of the actual electrodes fabricated from CNFs coated graphite particles was about 40% lower compared to the original pristine graphite electrodes.Peer reviewe

Single-Walled Carbon Nanotube Network Field Effect Transistor as a Humidity Sensor

Single-walled carbon nanotube network field effect transistors were fabricated and studied as humidity sensors. Sensing responses were altered by changing the gate voltage. At the open channel state (negative gate voltage), humidity pulse resulted in the decrease of the source-drain current, and, vice versa, the increase in the source-drain current was observed at the positive gate voltage. This effect was explained by the electron-donating nature of water molecules. The operation speed and signal intensity was found to be dependent on the gate voltage polarity. The positive or negative change in current with humidity pulse at zero-gate voltage was found to depend on the previous state of the gate electrode (positive or negative voltage, respectively). Those characteristics were explained by the charge traps in the gate dielectric altering the effective gate voltage, which influenced the operation of field effect transistor.Peer reviewe

The Relationship of Youth Family Values with Hedonism and Eudemonia

Introduction. A notable trend in modern society is the transformation of family institution, which has long been considered the most important social and personal value. The change of attitudes of young people towards marriage in Russia is slower than in Europe; however, this process is becoming more obvious today and there is an urgent need to study it. So far, very little research has been carried out. In psychology and other social sciences, it is widely believed that the family formation is hampered by a hedonistic worldview. However, it is well known that the family provides the opportunities to meet many important human needs. This contradiction has prompted the direction of the present research.The aim of this research is to empirically investigate whether there is the conflict of the perceptions of the Russian young people about family values and hedonic and eudemonic orientations.Methodology and research methods. The empirical research was conducted using K. Peterson’s questionnaire “Happiness Orientations”. 173 students (49% female) took part in the research project. To assess the importance of family and different family values, the authors of the present research elaborated a special questionnaire, the reliability of which was confirmed in the course of approbation. The information obtained was processed through the means of correlation, regression analysis and nonparametric statistics in Statistica 10; confirmatory factor analysis of questionnaires was performed in Mplus 7.Results. The results of path analysis of interrelations between hedonism, eudemonia and family values indicated that family values were correlated not only with the orientation to meaningful and dignified life (eudemonia), but also with the orientation to pleasure (hedonism). The orientation hedonism was higher in young women; therefore, multiple regression analysis of the relationship between the studied phenomena was conducted in separate male and female groups of respondents. The results demonstrated that the value of birth and child-rearing in women is correlated with hedonism; the general value of family in male respondents is related with eudemonia.Scientific novelty. This investigation confirms that there is no contradiction between hedonism and family values. The research findings deduce that both eudemonic and hedonic orientations support family values, although the system of relationships between these orientations may vary according to gender. This finding expands our knowledge about hedonism and its role in modern society.Practical significance. The research results expand the understanding of hedonism and its role in modern society, clarifying the content of activities to prepare young people for family life. In order to enhance the effectiveness of such psychological and pedagogical support, one should take into account the hedonic tendencies of young people, revealing the importance of family formation in the context of personal happiness.Введение. Одной из заметных тенденций в современном обществе является трансформация института семьи, которая в течение долгого времени считалась важнейшей социальной и личной ценностью. Изменение отношения молодых людей к браку в России происходит медленнее, чем в Европе, однако этот процесс становится все заметнее, что актуализирует необходимость его изучения. Пока подобные изыскания весьма немногочисленны. В психологии и других общественных науках распространено мнение о том, что созданию семьи препятствует гедонистическое мировоззрение. Вместе с тем хорошо известно, что именно семья предоставляет возможности для удовлетворения многих важных потребностей человека. Это противоречие обусловило направление предпринятого авторами статьи исследования. Цель представленной в публикации работы – выяснить, существует ли коллизия представлений юношей и девушек о семейных ценностях и характерных для нового поколения россиян гедонической и эвдемонической ориентаций. Методология и методы. Эмпирическое исследование, в котором приняли участие 173 студента (из них 49% девушек), проводилось с помощью опросника «Ориентации на счастье» К. Петерсона. Для оценки ценности семьи в целом и ее частных аспектов был составлен специальный опросник, надежность которого подтвердилась в ходе апробации. Полученная информация обрабатывалась посредством корреляционного, регрессионного анализа и непараметрической статистики в программе Statistica 10; конфирматорный факторный анализ опросников осуществлялся в программе Mplus 7.Результаты. Путевой анализ наличия / отсутствия связей гедонизма, эвдемонии и ценностей брака показал, что значимость семейной жизни для индивида прямо коррелирует с его стремлением не только к осмысленной и достойной жизни – с эвдемоническими установками, но и к удовольствиям – т. е. с гедонизмом. Последний оказался более выраженным у девушек, поэтому дополнительно был предпринят регрессионный анализ связей рассматриваемых феноменов отдельно для респондентов мужского и женского пола. Установлено, что у студенток ценность рождения и воспитания ребенка обусловлена гедонизмом, а общая ценность семьи для их ровесников-юношей – эвдемонией. Научная новизна. Продемонстрирована несостоятельность точки зрения о несовместимости гедонизма и семейных ценностей. Сделан вывод о том, что как эвдемоническая, так и гедоническая ориентация укрепляют ценность брака, хотя система отношений между ними может разниться в зависимости от гендерной принадлежности. Практическая значимость. Результаты исследования расширяют представления о гедонизме и его роли в современном обществе и позволяют уточнить содержание деятельности по подготовке молодежи к семейной жизни. В целях эффективности такого психолого-педагогического сопровождения следует учитывать гедонические наклонности молодежи, раскрывая важность создания семьи в контексте обретения личного счастья

Infrared properties of randomly oriented silver nanowires

We experimentally investigated the infrared properties of a set of randomly oriented silver nanowires films deposited onto glass substrate. Infrared emission of the obtained films was characterized in the long infrared range, i.e., 8–12 μm, by observing their temperature evolution under heating regime with a focal plane array infrared camera as well as a thermocouple. The obtained experimental results showed that the infrared emission from a mesh composed of silver nanowires might be tailored by opportunely assessing preparation condition, such as the metal filling factor. From the theoretical point of view, the real and imaginary part of the electrical permittivity components were retrieved from the calculations of effective permittivities of in-plane randomly oriented metallic wires, thus giving the refractive index and extinction coefficients for the four different silver nanowires meshes. Due to the correspondence between emissivity and absorbance, the experimental results are interpreted with the reconstructed corresponding absorbance spectra, thus suggesting that these coatings are suitable for infrared signature reduction applications.Peer reviewe

Transparent and flexible high-performance supercapacitors based on single-walled carbon nanotube films

Abstract Transparent and flexible energy storage devices have gathered great interest due to their suitability for display, sensor and photovoltaic applications. In this paper, we report the application of aerosol synthesized and dry deposited single-walled carbon nanotube (SWCNT) thin films as electrodes for electrochemical double-layer capacitor (EDLC). SWCNT films exhibit extremely large specific capacitance (178 F g -1 or 552 µF cm -2 ), high optical transparency (92%) and stability for 10000 charge/discharge cycles. A transparent and flexible EDLC prototype is constructed with a polyethylene casing and a gel electrolyte

Microwave reflectometry for magnetically confined plasmas

This paper is about microwave reflectometry -- a radar technique for plasma density measurements using the reflection of electromagnetic waves by a plasma cutoff. Both the theoretical foundations of reflectometry and its practical application to the study of magnetically confined plasmas are reviewed in this paper. In particular, the role of short-scale density fluctuations is discussed at length, both as a unique diagnostic tool for turbulence studies in thermonuclear plasmas and for the deleterious effects that fluctuations may have on the measurement of the average plasma density with microwave reflectometry