Additive Manufacturing (AM) is the significantly progressing field in terms of methods, materials, and performance of fabricated parts. Periodical evaluation on the understanding of AM processes and ...its evolution is needed since the field is growing rapidly. To address this requirement, this paper presents a detailed review of the Additive Manufacturing (AM) methods, materials used, and challenges associated with them. A critical review of the state of art materials in the categories such as metals and alloys, polymers, ceramics, and biomaterials are presented along with their applications, benefits, and the problems associated with the formation of microstructures, mechanical properties, and controlling process parameters. The perspectives and the status of different materials on the fabrication of thin-walled structures using AM techniques have also been discussed. Additionally, the main challenges with AM techniques such as inaccuracy, surface quality, reinforcement distribution, and other common problems identified from the literature are presented. On the whole, this paper provides a comprehensive outlook on AM techniques, challenges, and future research directions.
•A review on the basic and recent practices in additive manufacturing techniques is presented.•Use of metallic materials, ceramics, polymers, biomaterials and composites in additive manufacturing are reviewed.•Additive manufacturing in the fabrication of thin-walled structures and scaffolds are discussed.•The challenges in additive manufacturing found in literature and the scopes for future research works also detailed.
In this paper, we propose the application of a dual material gate (DMG) in a tunnel field-effect transistor (TFET) to simultaneously optimize the on-current, the off-current, and the threshold ...voltage and also improve the average subthreshold slope, the nature of the output characteristics, and immunity against the drain-induced barrier lowering effects. We demonstrate that, if appropriate work functions are chosen for the gate materials on the source side and the drain side, the TFET shows a significantly improved performance. We apply the technique of DMG in a strained double-gate TFET with a high- k gate dielectric to show an overall improvement in the characteristics of the device, along with achieving a good on-current and an excellent average subthreshold slope. The results show that the DMG technique can be applied to TFETs with different channel materials, channel lengths, gate-oxide materials, gate-oxide thicknesses, and power supply levels to achieve significant gains in the overall device characteristics.
Abstract
High quality silver (Ag) decorated CeO
2
nanoparticles were prepared by a facile one-step chemical method. The samples were characterized by X-ray diffraction (XRD), scanning electron ...microscopy (SEM), High resolution transmission electron microscopy (HR-TEM), fourier transform infrared spectrometer (FT-IR), electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), UV–Visible absorption (UV–Vis), photoluminescence (PL) and thermogravimetric analysis. The decoration of Ag on CeO
2
surface was confirmed by XRD, EPR and HR-TEM analysis. Harmful textile pollutant Rose Bengal dye was degraded under sunlight using the novel Ag decorated CeO
2
catalyst. It was found that great enhancement of the degradation efficiency for Ag/CeO
2
compared to pure CeO
2
, it can be ascribed mainly due to decrease in its band gap and charge carrier recombination rate. The Ag/CeO
2
sample exhibited an efficient photocatalytic characteristic for degrading RB under visible light irradiation with a high degradation rate of 96% after 3 h. With the help of various characterizations, a possible degradation mechanism has been proposed which shows the effect of generation of oxygen vacancies owing to the decoration of Ag on the CeO
2
surface.
Poly(lactic acid) (PLA) has become a “material of choice” in biomedical applications for its ability to fulfill complex needs that typically include properties such as biocompatibility, ...biodegradability, mechanical strength, and processability. Despite the advantages of pure PLA in a wider spectrum of applications, it is limited by its hydrophobicity, low impact toughness, and slow degradation rate. Blending PLA with other polymers offers a convenient option to enhance its properties or generate novel properties for target applications without the need to develop new materials. PLA blends with different natural and synthetic polymers have been developed by solvent and melt blending techniques and further processed based on end-use applications. A variety of PLA blends has been explored for biomedical applications such as drug delivery, implants, sutures, and tissue engineering. This review discusses the opportunities for PLA blends in the biomedical arena, including the overview of blending and postblend processing techniques and the applications of PLA blends currently in use and under development.
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Rapid urban development has led to a critical negative impact on water bodies flowing in and around urban areas. In the present study, 25 physiochemical and biological parameters have been studied on ...water samples collected from the entire section of a small river originating and ending within an urban area. This study envisaged to assess the water quality status of river body and explore probable sources of pollution in the river. Weighted arithmetic water quality index (WQI) was employed to evaluate the water quality status of the river. Multivariate statistical techniques namely cluster analysis (CA) and principal component analysis (PCA) were applied to differentiate the sources of variation in water quality and to determine the cause of pollution in the river. WQI values indicated high pollution levels in the studied water body, rendering it unsuitable for any practical purpose. Cluster analysis results showed that the river samples can be divided into four groups. Use of PCA identified four important factors describing the types of pollution in the river, namely (1) mineral and nutrient pollution, (2) heavy metal pollution, (3) organic pollution, and (4) fecal contamination. The deteriorating water quality of the river was demonstrated to originate from wide sources of anthropogenic activities, especially municipal sewage discharge from unplanned housing areas, wastewater discharge from small industrial units, livestock activities, and indiscriminate dumping of solid wastes in the river. Thus, the present study effectively demonstrates the use of WQI and multivariate statistical techniques for gaining simpler and meaningful information about the water quality of a lotic water body as well as to identify of the pollution sources.
Context: Soy is the main source of phytoestrogens, which has long been used as traditional food. One major subtype of phytoestrogens includes isoflavones and they are scientifically validated for ...their beneficial actions on many hormone-dependent conditions.
Objective: The present study examines the effect of soy isoflavones on letrozole-induced polycystic ovary syndrome (PCOS) rat model.
Materials and methods: PCOS was induced in Sprague-Dawley rats with of 1 mg/kg letrozole, p.o. once daily for 21 consecutive days. Soy isoflavones (50 and 100 mg/kg) was administered for 14 days after PCOS induction. Physical parameters (body weight, oestrous cycle determination, ovary and uterus weight) metabolic parameters (oral glucose tolerance test, total cholesterol), steroidal hormone profile (testosterone and 17β-oestradiol), steroidogenic enzymes (3β-hydroxy steroid dehydrogenase (HSD) and 17β-HSD), oxidative stress and histopathology of ovary were studied.
Results: Soy isoflavones (100 mg/kg) treatment significantly altered the letrozole-induced PCOS symptoms as observed by decreased body weight gain (p < 0.05), percentage diestrous phase (p < 0.001), testosterone (p < 0.001), 3β-HSD (p < 0.01) and 17β-HSD (p < 0.001) enzyme activity and oxidative stress. Histological results reveal that soy isoflavones treatment in PCOS rats resulted in well-developed antral follicles and normal granulosa cell layer in rat ovary.
Discussion: Treatment with soy isoflavones exerts beneficial effects in PCOS rats (with decreased aromatase activity) which might be due to their ability to decrease testosterone concentration in the peripheral blood.
Conclusion: Analysis of physical, biochemical and histological evidences shows that soy isoflavones may be beneficial in PCOS.
•Imposition of restriction on people movement plays a vital role in global air quality concentration levels.•The concentration of major air pollutants was measured during lockdown period and compared ...with previous years.•There is a significant reduction in Annual monthly average of air pollutants concentration due to impact of COVID-19.•The outbreak of COVID-19 around the globe was assessed.
It is well known that pandemics not only change people's social habits but have also changed most activities related to energy consumption, especially industry and transport. Over the past year, a plethora of case studies have been published mapping the environmental impacts in specific locations in terms of changes in wastewater composition, noise, solar radiation and more. However, policymakers are demanding a global perspective and are looking for a synthesis of all these reports that will indicate whether, or to what extent, these changes interact with global climate change. The most urgent question is whether artificially inducing such a pandemic could be justified, given the loss of human life and economic losses. Robust analysis on air pollutants such as PM2.5, PM10, NOx, SO2, CO, O3 and NH3 confirmed significant improvement in air quality indicators especially in India and China. The study indicates that key hypotheses can be confirmed or refuted, but further measurements are needed.
Emerging contaminants include many synthetic or natural substances, such as pharmaceuticals and personal care products, hormones, and flame retardants that are not often controlled or monitored in ...the environment. The consumption or use of these substances is on an ever-rising trend, which dangerously increases their prevalence in practically all environmental matrices. These contaminants are present in low environmental concentrations and cause severe effects on human health and the biota. The present review analyzed 2012–2022 years papers via PubChem, science direct, National Center for Biotechnology Information, web of science on the legislations and policies of emerging contaminants globally. A state-of-the-art review of several studies in the literature focus on examining and evaluating the emerging contaminants and the frameworks adopted by developed and developing countries to combat the release of emerging contaminants and form footprints towards water sustainability which includes water availability, usage patterns, generation and pollution management, the health of aquatic systems, and societal vulnerability. The paper aims to provide a comprehensive view of current global policies and framework regarding evaluating and assessing the chemicals, in light of being a threat to the environment and biota. The review also highlights the future global prospects, including current governmental activities and emerging contaminant policy measures. The review concludes with suggestions and way forward to control the inventory and disposal of emerging contaminants in the environment.
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•ECs are ubiquitous in the environment and have serious effects on humans and wildlife.•The main source of pollution in ECs is wastewater effluent.•Detection and screening of nontarget with effect-directed analysis.•Policies on the manufacturing, use, and release of ECs globally must be formulated.•Collective support from both scientists and legislators can help combat EC pollution in the environment.
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