A LED-based Functional Light Source for the Characterization of Thin Film Solar Cells

A light source of selective functionalities of wavelengths, illumination periods, and intensities is desirable for investigating performance parameters as well as the quality of different layers and interfaces of solar cells. Conventional light sources used for these types of research are expensive, space-consuming, cumbersome to work with, and have limited functionalities. We have developed a light source with variable wavelength, intensity, and illumination period to address these issues using an illumination period control unit, voltage regulator, neutral density filter, alterable light emitting diodes, etc. As a proof-of-concept, we employed our constructed light source to investigate the intensity, wavelength, illumination period modulated photovoltaic, and impedance properties of inorganic thin film solar cells such as cadmium telluride (CdTe) and copper zinc tin sulfide (CZTS) using lights of wavelength 410, 520, and 635 nm. We hope to use this light source for photophysical and photochemical studies of metal oxide materials used for renewable energy research.Comment: 4 pages, 7 figure

Sustainability through the Lens of Environmental Sociology

Our planet is undergoing radical environmental and social changes. Sustainability has now been put into question by, for example, our consumption patterns, loss of biodiversity, depletion of resources, and exploitative power relations. With apparent ecological and social limits to globalization and development, current levels of consumption are unsustainable, inequitable, and inaccessible to the majority of humans. Understanding and attaining sustainability is a crucial matter at a time when our planet is in peril—environmentally, economically, socially, and politically. Since its official inception in the 1970s, environmental sociology has provided a powerful lens to understanding the challenges, possibilities and modes of sustainability. Most chapters in this book were published as peer-reviewed articles in Sustainability in its special issue “Sustainability through the Lens of Environmental Sociology”, providing an environmental sociology approach to understanding and achieving the widely used notion of “sustainability.” This edited collection covers, among other topics, the inherent discursive formations of environmental sociology, conceptual tools and paradoxes, competing theories and practices, and their complex implications on our society at large. Chapters in this book specifically focus on how sustainable development has been understood through different theoretical lenses in environmental sociology, such as ecological modernization, policy/reformist sustainable development, and critical structural approaches (such as the treadmill of production, ecological Marxism, metabolic rift theory, etc.); and how sustainable development has been practiced in, or by, various stakeholders, such as states, corporations, and local communities, for various ends, through the use of specific case studies, showing, for example, the discursive shifts, dynamic formations, and diverse contours of sustainable development. The range of relevant topics includes: • Environmental sociology as a field of inquiry for sustainability • Historical context of sustainable development in environmental sociology • Nature-society relationship in environmental sociology • Theories/approaches to sustainability discourse in environmental sociology • Environmentalism/environmental movements for sustainability • Empirical cases (such as climate change, biodiversity, food, certification, etc.) through the lens of environmental sociolog

Spectral Numerical Calculation of Non-isothermal Flow through a Rotating Curved Rectangular Duct with Moderate Curvature

The present paper investigates non-isothermal flow characteristics through a rotating curved rectangular duct, where co-existence of the rotational forces and fluid temperature gradients leads to the emergence of rotation-induced buoyancy effects. A spectral-based numerical scheme is employed as the principal tool for the simulation while Chebyshev polynomial and collocation method as the secondary tools. The outer wall of the duct is heated while the inner wall cooled, the top and bottom walls being thermally insulated. The emerging parameters controlling the flow characteristics are the rotation parameter, i.e., the Taylor number Tr ranging 0 to 2000, the Grashof number Gr = 100, the Prandtl number Pr, the aspect ratio, and the pressure-driven parameter, i.e., the Dean number Dn between 100 and 1000. The flow structures are examined under combined action of the centrifugal, Coriolis and buoyancy forces. As a result, asymmetric 2-cell structures are computed for small values of Tr while asymmetric 6-cell structures for large Tr. Unsteady flow characteristics show that the flow undergoes in the scenario ‘chaotic→ multi-periodic → periodic→ steady-state’, if Tr is increased in the positive direction. Typical contours of secondary flow patterns, temperature profiles and axial flow distribution are also obtained at several values of Tr, and it is found that there exist asymmetric two- to multi-vortex solutions. Heating the outer wall is found to generate a significant temperature gradient at the outer concave wall

Sociological perspectives on climate change and society: A review

Ministry of Education, Singapore under its Academic Research Funding Tier

Pressure-driven Flow Instability with Convective Heat Transfer Through a Curved Rectangular Duct of Small Aspect Ratio

AbstractThe present study investigates unsteady fluid flow through a curved rectangular duct of aspect ratio 0.5 and curvature 0.5. Numerical calculations are carried out by using a spectral method, and covering a wide range of the pressure gradient parameter, the Dean number, 6000 ≤ Dn ≤ 12000 and the Grashof number, 100 ≤ Gr ≤ 2000 for two cases of the duct, Case-I: Stationary duct and Case-II: Rotating duct. The outer wall of the duct is heated while the inner wall cooled. The main concern of the present study is to discuss the unsteady flow behavior i.e whether the unsteady flow is steady-state, periodic, multi-periodic or chaotic, if Dn or Gr is increased. For a stationary duct, we investigate the unsteady flow characteristics for the Dean number 6000 ≤ Dn ≤ 12000 and the Grashof number 100 ≤ Gr ≤ 2000, and it is found that the unsteady flow undergoes in the scenario steady-state → periodic → multi-periodic → chaotic, if Gr is increased. For rotating duct, however, we investigate the unsteady flow characteristics for the Taylor number −100 Tr ≤ 1000, and it is found that the unsteady flow undergoes through various flow instabilities, if Dn or Gr is increased. Typical contours of secondary flow patterns and temperature profiles are also obtained, and it is found that the unsteady flow consists of a single-, two-, and multi-vortex solutions

Effect of Substrate Surface on the Wide Bandgap SnO2 Thin Films Grown by Spin Coating

Tin (IV) oxide (SnO2) sols have been synthesized from SnCl2.2H2O precursor solution by applying two different processing conditions. The prepared sols were then deposited on UV-Ozone treated quartz and soda lime glass (SLG) substrates by spin coating. The as-synthesized film was soft-baked at about 100 deg. C. for 10 min. This process was repeated five times to get a compact film, followed by air-annealing at 250 deg. C. for 2 h. The pristine and annealed films were characterized by UV-Vis-NIR spectroscopy, Grazing Incident X-Ray Diffraction (GIXRD), and Field Emission Scanning Electron Microscope (FESEM). The effect of substrate surface was investigated by measuring the contact angles with De-Ionized (DI) water. UV-Ozone treatment of substrate provides a cleaner surface to grow a homogeneous film. The electrical resistivity of annealed thin films was carried out by a four-point-collinear probe employing the current reversal technique and found in the range of approx. 2x10^3 to 3x10^3 Ohm.cm. Film thickness was found in the range of approx. 137-285 nm, measured by a stylus profilometer. UV-Vis-NIR Transmission data revealed that all the thin film samples showed maximum (82-89) % transmission in the visible range. The optical bandgap of the thin films was estimated to be approx. 3.75 to 4.00 eV and approx. 3.78 to 4.35 eV for the films grown on SLG and quartz substrates, respectively.Comment: 4 pages, 7 figure

Emerging trends in aquaculture value chain research

This paper introduces a special issue of Aquaculture that brings together the largest collection of research on aquaculture value chains compiled to date, comprising 19 individual papers and this introductory review. The introduction identifies five themes emerging from research on aquaculture value chains in the special issue, namely: multi-polarity, diversity and scale, dynamics of transformation, performance and equity, and technical and institutional innovation. Contrary to much research to date, the papers addressing these themes show how the expansion of aquaculture has resulted highly diverse configurations of production for consumption in the global South. Collectively, the papers highlight the need for greater attention to neglected value chain segments and categories of actor, modes of production, regulation, and innovation, and patterns of access to benefits. The papers synthesized also affirm the need for more rigorous and diverse future value chain research to illuminate the aquaculture sector's ongoing development, and contribute to the sustainable expansion as an increasingly important component of the global food system

PERFORMANCE OF SUSTAINABLE GREEN CONCRETE INCORPORATED WITH FLY ASH, RICE HUSK ASH, AND STONE DUST

The performance of a sustainable green concrete with fly ash (FA), rice husk ash (RHA), and stone dust (SD) as a partial replacement of cement and sand was experimentally explored. FA and RHA have a high silica content, are highly pozzolanic in nature and have a high surface area without any treatment. These by-products show filler effects, which enhance concrete’s density. Results showed that the FA and RHA materials have good hydration behaviour and effectively develop strength at an early age of concrete. SD acts as a stress transferring medium within concrete, thereby allowing the concrete to be stronger in compression, and bending. Consequently, water absorption capacity of the sustainable concrete was lower than that of the ordinary one. However, a little reduction in strength was observed after the replacement of the binder and aggregate using the FA, RHA and SD, but the reduction was insignificant. The reinforced structure with sustainable concrete containing the FA, RHA, and SD generally fails in concrete crushing tests initiated by flexural cracking followed by shear cracks. The sustainable concrete could be categorized as a perfect material with no significant conciliation in strength properties and can be applied to design under-reinforced elements for a low-to-moderate service load

A 10-year-old boy presented with recurrent episodes of diarrhea, low grade, irregular fever and severe wasting

This article has no abstract. The first 100 words appear below: A 10-year old boy, the only issue of his deceased parents, was admitted to the department for the management of recurrent episodes of diarrhea and severe wasting for 2.5 months, low grade, irregular fever with evening rise of temperature, anorexia and repeated attack of skin blister for the last 1 year. The patient complained of chronic, painless, non-bloody, profuse watery diarrhea with a weight loss of 10 kg (decrease to 18 kg from 28 kg prior to illness). He also complained of cough for the last seven days. His father was a driver and died at his 1 year of age due to an unknown disease

BenLLMEval: A Comprehensive Evaluation into the Potentials and Pitfalls of Large Language Models on Bengali NLP

Large Language Models (LLMs) have emerged as one of the most important breakthroughs in natural language processing (NLP) for their impressive skills in language generation and other language-specific tasks. Though LLMs have been evaluated in various tasks, mostly in English, they have not yet undergone thorough evaluation in under-resourced languages such as Bengali (Bangla). In this paper, we evaluate the performance of LLMs for the low-resourced Bangla language. We select various important and diverse Bangla NLP tasks, such as abstractive summarization, question answering, paraphrasing, natural language inference, text classification, and sentiment analysis for zero-shot evaluation with ChatGPT, LLaMA-2, and Claude-2 and compare the performance with state-of-the-art fine-tuned models. Our experimental results demonstrate an inferior performance of LLMs for different Bangla NLP tasks, calling for further effort to develop better understanding of LLMs in low-resource languages like Bangla.Comment: First two authors contributed equall