Transport Properties of Thermoelectric Nanocomposites

2009 ◽  
Vol 1166 ◽  
Author(s):  
Lilia M Woods ◽  
Adian Popescu ◽  
Joshua Martin ◽  
George S. Nolas
Keyword(s):  
Experimental Data ◽  
Transport Process ◽  
Scattering Mechanism ◽  
Optimum Regime ◽  
Thermoelectric Transport ◽  
Potential Barriers ◽  
Barrier Heights ◽  
Carrier Scattering ◽  
Key Factor

AbstractWe present a theoretical model for carrier conductivity and Seebeck coefficient of thermoelectric materials composed of nanogranular regions. The model is used to successfully describe experimental data for chalcogenide PbTe nanocomposites. We also present similar calculations for skutterudite CoSb3 nanocomposites. The carrier scattering mechanism is considered explicitly and it is determined that it is a key factor in the thermoelectric transport process. The grain interfaces are described as potential barriers. We investigate theoretically the role of the barrier heights, widths, and distances between the barriers to obtain an optimum regime for the composites thermoelectric characetristics.

scholarly journals OBSTACLES TO THE EMPLOYMENT OF THE PERSONS WITH DISABILITIES FROM THE EMPLOYER'S PERSPECTIVE

2021 ◽  
Vol 4 (1) ◽  
pp. 43-52
Author(s):  
Vesna Paušić ◽  
Tatjana Krstić ◽  
Jelena Vidojević
Keyword(s):  
People With Disabilities ◽  
Private Companies ◽  
Persons With Disabilities ◽  
Potential Barriers ◽  
Prior Consent ◽  
Barriers To Employment ◽  
Key Factor ◽  
Novi Sad ◽  
The City

The role of employers in obtaining a job for people with disabilities can be crucial. The law on “Professional rehabilitation and employment of people with disabilities” was supposed to be a key factor in improving the position of this population in the labor market, but in practice this has not been confirmed. One of the major obstacles to the employment of persons with disabilities is the lack of a register of persons with disabilities where employers colud find potential candidates with appropriate skills and competencies. This research was conducted with the aim of identifying potential barriers to employment of persons with disabilities perceived from the perspective of employers. The sample consisted of 50 employers of both state and private companies in the city of Novi Sad. Employers were surveyed with a questionnaire created for the purposes of this research, modeled on the Employers' Motivation Questionnaire for Employment of Persons with Disabilities with the prior consent of the author. The results schow that the adaptation of the workplace and access to means of transport are the biggest obstacle when we are talking about employing people with disabilities. In order to gain a deeper insight into the perspective of employers regarding the employment of people with disabilities, it is important to take into account their direct experiences as well as what worries them and what they feel insufficiently competent when it comes to employing this population. Key words: people with disabilities, employers, barriers.

THE ROLE OF SURFACE ENERGY COEFFICIENT IN HEAVY ION REACTIONS AND IMPROVED PROXIMITY MODEL

2011 ◽  
Vol 20 (11) ◽  
pp. 2337-2349 ◽  
Author(s):  
M. SALEHI ◽  
O. N. GHODSI
Keyword(s):  
Experimental Data ◽  
Surface Tension ◽  
Surface Energy ◽  
Heavy Ion ◽  
Surface Tension Coefficient ◽  
Proximity Potential ◽  
Fusion Barrier ◽  
Barrier Heights ◽  
Energy Coefficient

In this work we have discussed dependence of surface tension coefficient that appears in proximity potential and energy of incident nucleus. The obtained results from study of the fusion barrier heights and positions for 44 reactions with z≥8 reveal that this modification on the formalism of proximity model leads to a better agreement between computed fusion barrier heights and positions and experimental data.

Kernrelaxation und behinderte Rotation in organischen Festkörpern bei tiefen Temperaturen

1968 ◽  
Vol 23 (2) ◽  
pp. 208-216 ◽  
Author(s):  
J. Haupt ◽  
W. Müller-Warmuth
Keyword(s):  
Experimental Data ◽  
Low Temperatures ◽  
Degrees Of Freedom ◽  
Theoretical Treatment ◽  
Relaxation Rates ◽  
Kcal Mole ◽  
Potential Barriers ◽  
Barrier Heights ◽  
Second Moments ◽  
Quantitative Explanation

The proton magnetic resonance and relaxation of o-, m- and p-xylene has been studied at various temperatures between the melting point and 2°K. Motionally narrowed second moments of the proton lines of about 10 G2 have been observed over the whole temperature range. Spinlattice relaxation is effective at rather low temperatures and can no longer be interpreted in terms of classical hindered rotations of the methyl groups. Quantum mechanical tunneling through the barriers hindering the reorientations is considered instead. Furthermore it is proposed to explain the observed decay of relaxation rates at low temperatures as a consequence of some kind of bottleneck in the energy transfer between torsional motions and other degrees of freedom in the solid. On the basis of a simplified model a quantitative explanation of the experimental data has been possible using elements of the theoretical treatment of Stejskal and Gutowsky. The potential barriers are of sixfold and of threefold symmetry. From the experimental data absolute barrier heights of 2,2 (o-xylene), 0,27 (m-xylene) and 1,1 kcal/Mole (p-xylene) could be calculated.

РОЛЬ ФИЗИЧЕСКОЙ РАЗМИНКИ В ПОДГОТОВКЕ К ТРЕНИРОВОЧНЫМ ЗАНЯТИЯМ И СОРЕВНОВАНИЯМ ШАХМАТИСТОВ БГУ

2019 ◽  
pp. 63-65
Author(s):  
Судоргин Е.П. ◽  
Карсакова И.Н.
Keyword(s):  
Experimental Data ◽  
Sport Performance ◽  
Warm Up ◽  
Physical Exercises ◽  
Methods Of Evaluation ◽  
Mental Fitness ◽  
Physical Preparation ◽  
Tools And Methods

Аннотация: О роли разминки перед тренировкой и соревнованиями написано много научных статьей и диссертаций. Ещё больше о значимости физической подготовки спортсменов, в том числе и шахматистов. В то же время авторы считают, что вопросу физической подготовки шахматистов и в частности разминке в научной и научно-методической литературе уделяется недостаточно внимания. В своей статье авторы приводят собственные экспериментальные данные о влиянии физических упражнений (разминки) на умственную работоспособность студентов-шахматистов БГУ и как следствие на спортивные результаты команды. Ключевые слова: Шахматы, разминка, умственная работоспособность, средства и методы разминки, методы оценки результатов. Аннотация: Машыгуунун жана мелдештердин алдында даярдоонун ролу жөнүндө көптөгөн илимий макала жана диссертация жазылган. Ошондой эле илимий жана илимий-методикалык адабияттарда шахматка даярдоого көп көңүл бурулбай жатат. Макаланын авторлору шахмат ойногон студенттерге физикалык көнүгүүлөрдүн тийгизген таасири жөнүндө өздөрүнүн эксперименталдык маалыматтарын көргөзүштү. Түйүндүү сөздөр: Шахмат, акыл-дарамет, курулуштар жана ыкмалар, баа берүү жыйынтыгы боюнча кабыл алынат. Abstract: on the role of warm-up before training and competitions written many scientific articles and theses. More about the significance of the physical preparation of athletes, including players. At the same time, the authors believe that the issue of fit- ness players and in particular workout in scientific and scientific-methodical literature neglected. In his article the authors cite their own experimental data on the influence of physical exercises (warm-up) on the mental fitness of students-BSU players and as a result the sport performance team. Keywords: chess, warm-up, mental fitness, workout tools and methods, methods of evaluation results.

scholarly journals Protective Role of Glutathione in the Hippocampus after Brain Ischemia

2021 ◽  
Vol 22 (15) ◽  
pp. 7765
Author(s):  
Youichirou Higashi ◽  
Takaaki Aratake ◽  
Takahiro Shimizu ◽  
Shogo Shimizu ◽  
Motoaki Saito
Keyword(s):  
Oxidative Stress ◽  
Neuronal Death ◽  
Excitatory Amino Acid ◽  
Ischemia Reperfusion ◽  
Thiol Group ◽  
Protective Role ◽  
Key Factor ◽  
Rate Limiting ◽  
Cysteine Uptake

Stroke is a major cause of death worldwide, leading to serious disability. Post-ischemic injury, especially in the cerebral ischemia-prone hippocampus, is a serious problem, as it contributes to vascular dementia. Many studies have shown that in the hippocampus, ischemia/reperfusion induces neuronal death through oxidative stress and neuronal zinc (Zn2+) dyshomeostasis. Glutathione (GSH) plays an important role in protecting neurons against oxidative stress as a major intracellular antioxidant. In addition, the thiol group of GSH can function as a principal Zn2+ chelator for the maintenance of Zn2+ homeostasis in neurons. These lines of evidence suggest that neuronal GSH levels could be a key factor in post-stroke neuronal survival. In neurons, excitatory amino acid carrier 1 (EAAC1) is involved in the influx of cysteine, and intracellular cysteine is the rate-limiting substrate for the synthesis of GSH. Recently, several studies have indicated that cysteine uptake through EAAC1 suppresses ischemia-induced neuronal death via the promotion of hippocampal GSH synthesis in ischemic animal models. In this article, we aimed to review and describe the role of GSH in hippocampal neuroprotection after ischemia/reperfusion, focusing on EAAC1.

scholarly journals Oxidation of Terpenoids to Achieve High-Value Flavor and Fragrances—Questioning Microalgae Oxidative Capabilities in the Biotransformation of the Sesquiterpene Valencene and of Selected Natural Apocarotenoids

Chemistry ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 821-830
Author(s):  
Davide De Simeis ◽  
Stefano Serra ◽  
Alessandro Di Fonzo ◽  
Francesco Secundo
Keyword(s):  
Experimental Data ◽  
Natural Products ◽  
Aqueous Medium ◽  
Photochemical Reaction ◽  
Substrate Oxidation ◽  
Market Size ◽  
Chlorella Sp ◽  
General Opinion ◽  
Natural Way

Natural flavor and fragrance market size is expected to grow steadily due to the rising consumer demand of natural ingredients. This market request is guided by the general opinion that the production of natural compounds leads to a reduction of pollution, with inherent advantages for the environment and people’s health. The biotransformation reactions have gained high relevance in the production of natural products. In this context, few pieces of research have described the role of microalgae in the oxidation of terpenoids. In this present study, we questioned the role of microalgal based oxidation in the synthesis of high-value flavors and fragrances. This study investigated the role of three different microalgae strains, Chlorella sp. (211.8b and 211.8p) and Chlorococcum sp. (JB3), in the oxidation of different terpenoid substrates: α-ionone, β-ionone, theaspirane and valencene. Unfortunately, the experimental data showed that the microalgal strains used are not responsible for the substrate oxidation. In fact, our experiments demonstrate that the transformation of the four starting compounds is a photochemical reaction that involves the oxygen as oxidant. Even though these findings cast a shadow on the use of these microorganisms for an industrial purpose, they open a new possible strategy to easily obtain nootkatone in a natural way by just using an aqueous medium, oxygen and light.

scholarly journals Changing Technology or Behavior? The Impacts of a Behavioral Disruption

2021 ◽  
Vol 13 (11) ◽  
pp. 5861
Author(s):  
Marianne Pedinotti-Castelle ◽  
Pierre-Olivier Pineau ◽  
Kathleen Vaillancourt ◽  
Ben Amor
Keyword(s):  
Energy Transition ◽  
Energy System ◽  
Behavior Changes ◽  
Ghg Emission ◽  
The North ◽  
Behavioral Disruption ◽  
Transportation Sector ◽  
Key Factor ◽  
Additional Costs

Transportation is a key factor in the fight against climate change. Consumer behavior changes in transportation are underrepresented in energy policies, even if they could be essential to achieve the fixed GHG emission reduction targets. To help quantify the role of behaviors in energy transition and their implications on the dynamics of an energy system, this study is conducted using the North American TIMES Energy Model, adapted to Quebec (Canada). A behavioral disruption scenario (an increase in carpooling) is introduced in the model’s transportation sector and is compared to a massive electrification scenario. Our results highlight the fact that a behavioral disruption can lead to the same GHG emission reductions (65%) by 2050 as an electrification policy, while alleviating different efforts (such as additional electrical capacity and additional costs) associated with massive electrification. Moreover, the results are sensitive to behavior-related parameters, such as social discount rates and car lifetimes.

scholarly journals sFasL—The Key to a Riddle: Immune Responses in Aging Lung and Disease

2021 ◽  
Vol 22 (4) ◽  
pp. 2177
Author(s):  
Shulamit B. Wallach-Dayan ◽  
Dmytro Petukhov ◽  
Ronit Ahdut-HaCohen ◽  
Mark Richter-Dayan ◽  
Raphael Breuer
Keyword(s):  
Cell Death ◽  
Lung Disease ◽  
Fas Ligand ◽  
Death Receptor ◽  
Mesenchymal Cells ◽  
Soluble Form ◽  
Cell Accumulation ◽  
Key Factor ◽  
Aged Subjects

By dint of the aging population and further deepened with the Covid-19 pandemic, lung disease has turned out to be a major cause of worldwide morbidity and mortality. The condition is exacerbated when the immune system further attacks the healthy, rather than the diseased, tissue within the lung. Governed by unremittingly proliferating mesenchymal cells and increased collagen deposition, if inflammation persists, as frequently occurs in aging lungs, the tissue develops tumors and/or turns into scars (fibrosis), with limited regenerative capacity and organ failure. Fas ligand (FasL, a ligand of the Fas cell death receptor) is a key factor in the regulation of these processes. FasL is primarily found in two forms: full length (membrane, or mFasL) and cleaved (soluble, or sFasL). We and others found that T-cells expressing the mFasL retain autoimmune surveillance that controls mesenchymal, as well as tumor cell accumulation following an inflammatory response. However, mesenchymal cells from fibrotic lungs, tumor cells, or cells from immune-privileged sites, resist FasL+ T-cell-induced cell death. The mechanisms involved are a counterattack of immune cells by FasL, by releasing a soluble form of FasL that competes with the membrane version, and inhibits their cell death, promoting cell survival. This review focuses on understanding the previously unrecognized role of FasL, and in particular its soluble form, sFasL, in the serum of aged subjects, and its association with the evolution of lung disease, paving the way to new methods of diagnosis and treatment.

scholarly journals Theoretical Study on the Photo-Oxidation and Photoreduction of an Azetidine Derivative as a Model of DNA Repair

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2911
Author(s):  
Miriam Navarrete-Miguel ◽  
Antonio Francés-Monerris ◽  
Miguel A. Miranda ◽  
Virginie Lhiaubet-Vallet ◽  
Daniel Roca-Sanjuán
Keyword(s):  
Electron Transfer ◽  
Energy Barrier ◽  
Ring Opening ◽  
Dna Lesions ◽  
Barrier Heights ◽  
Dna Lesion ◽  
Electron Reduction ◽  
The Stability ◽  
Electron Transfer Processes

Photocycloreversion plays a central role in the study of the repair of DNA lesions, reverting them into the original pyrimidine nucleobases. Particularly, among the proposed mechanisms for the repair of DNA (6-4) photoproducts by photolyases, it has been suggested that it takes place through an intermediate characterized by a four-membered heterocyclic oxetane or azetidine ring, whose opening requires the reduction of the fused nucleobases. The specific role of this electron transfer step and its impact on the ring opening energetics remain to be understood. These processes are studied herein by means of quantum-chemical calculations on the two azetidine stereoisomers obtained from photocycloaddition between 6-azauracil and cyclohexene. First, we analyze the efficiency of the electron-transfer processes by computing the redox properties of the azetidine isomers as well as those of a series of aromatic photosensitizers acting as photoreductants and photo-oxidants. We find certain stereodifferentiation favoring oxidation of the cis-isomer, in agreement with previous experimental data. Second, we determine the reaction profiles of the ring-opening mechanism of the cationic, neutral, and anionic systems and assess their feasibility based on their energy barrier heights and the stability of the reactants and products. Results show that oxidation largely decreases the ring-opening energy barrier for both stereoisomers, even though the process is forecast as too slow to be competitive. Conversely, one-electron reduction dramatically facilitates the ring opening of the azetidine heterocycle. Considering the overall quantum-chemistry findings, N,N-dimethylaniline is proposed as an efficient photosensitizer to trigger the photoinduced cycloreversion of the DNA lesion model.

scholarly journals Innovative Work Behavior—A Key Factor in Business Performance? The Role of Team Cognitive Diversity and Teamwork Climate in This Relationship

2021 ◽  
Vol 14 (4) ◽  
pp. 185
Author(s):  
Nadežda Jankelová ◽  
Zuzana Joniaková ◽  
Juraj Mišún
Keyword(s):  
Business Performance ◽  
Main Tool ◽  
Work Behavior ◽  
Cognitive Diversity ◽  
Staff Perceptions ◽  
Innovative Work Behavior ◽  
Positive Effects ◽  
Key Factor ◽  
Innovative Work

The aim of our paper is to examine whether the support of innovative work behavior by management is positively related to business performance and at the same time, whether this relationship is mediated by the teamwork climate and cognitive diversity of teams. Cognitive diversity is defined as differences in knowledge and perspective, which arise from professional diversity and account for its positive effects. A teamwork climate represents staff perceptions of collaboration between personnel. Business performance is defined by the level of sales. Our sample consisted of 211 managers of companies operating in Slovakia, and data collection took place in the form of a questionnaire. The main tool for examining the mechanism of operation of the investigated relationships is mediation using regression analysis and the Sobel test to determine the significance of the indirect effect of mediation variables. The findings point to a significant direct relationship between the innovative work behavior of company employees and business performance. The intensity of this relationship can be partly influenced by promoting cognitive diversity, especially in the area of knowledge and ways of thinking. The significant role of a teamwork climate was not demonstrated in the examined model.

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