The sealed cavity pressure of a micro-package often becomes the determining factor of the performance of an encapsulated micro-electro mechanical system (MEMS). In this study, a sealed cavity ...pressure evaluation method for a micro-package using a thin diaphragm is studied comprehensively. The sealed cavity pressure is identical to the surrounding pressure when the diaphragm separating both volumes becomes flat, i.e. zero-balance method. The zero-balance method has advantages to other techniques in terms of fabrication process simplicity and pressure evaluation range. Two approaches are introduced to reduce the impact of the residual stress, which typically exists in the conventionally used silicon-on-insulator (SOI) diaphragm. The introduction of a stress compensation layer was able to reduce the impact of the residual stress of SOI-based diaphragms. However, a significant hysteresis is developed on the diaphragm, which limits the precise measurement of a sealed cavity. On the other hand the residual stress can be avoided by the usage of intentionally tensile stressed boron doped Si diaphragm, which is produced by alkaline wet etching. Using such a diaphragm, a sealed cavity pressure of several Pa can be measured with a single digit Pa accuracy. 2020-0014
The adsorption of lead(II) and cadmium(II) on peels of banana has been studied in batch mode using flame atomic absorption spectroscopy for metal estimation. Concerned parameters like adsorbent dose, ...pH, contact time and agitation speed were investigated. Langmuir, Freundlich and Temkin isotherms were employed to describe adsorption equilibrium. The maximum amounts of cadmium(II) and lead(II) adsorbed (
qm), as evaluated by Langmuir isotherm, were 5.71
mg and 2.18
mg per gram of powder of banana peels, respectively. Study concluded that banana peels, a waste material, have good potential as an adsorbent to remove toxic metals like lead and cadmium from water.
We present a single-layer metasurface, which performs both cross and circular polarization conversion at multiple frequency bands. The unit cell of the proposed metasurface consists of periodic array ...of a uniquely designed hexagonal split ring resonator (SRR). The proposed metasurface behaves as an efficient 90° polarization rotator at dual frequency bands of 6.36-6.59 GHz and 10.54-13.56 GHz. The polarization conversion efficiency approaches 90% within these two operating bands. Moreover, linear-to-circular polarization conversion is also achieved in other three wide frequency bands from 6.10-6.20 GHz, 6.84-9.02 GHz and 14.10-15.48 GHz. The novel features of the subject hexagonal metasurface, which qualify it for numerous practical applications are high cross-polarization conversion (CPC) efficiency, wideband operation and angular stability for oblique incidence up to 45°.
Plants are a major source of food for the world population. Plant diseases contribute to production loss, which can be tackled with continuous monitoring. Manual plant disease monitoring is both ...laborious and error-prone. Early detection of plant diseases using computer vision and artificial intelligence (AI) can help to reduce the adverse effects of diseases and also overcome the shortcomings of continuous human monitoring. In this work, we propose the use of a deep learning architecture based on a recent convolutional neural network called EfficientNet on 18,161 plain and segmented tomato leaf images to classify tomato diseases. The performance of two segmentation models i.e., U-net and Modified U-net, for the segmentation of leaves is reported. The comparative performance of the models for binary classification (healthy and unhealthy leaves), six-class classification (healthy and various groups of diseased leaves), and ten-class classification (healthy and various types of unhealthy leaves) are also reported. The modified U-net segmentation model showed accuracy, IoU, and Dice score of 98.66%, 98.5%, and 98.73%, respectively, for the segmentation of leaf images. EfficientNet-B7 showed superior performance for the binary classification and six-class classification using segmented images with an accuracy of 99.95% and 99.12%, respectively. Finally, EfficientNet-B4 achieved an accuracy of 99.89% for ten-class classification using segmented images. It can be concluded that all the architectures performed better in classifying the diseases when trained with deeper networks on segmented images. The performance of each of the experimental studies reported in this work outperforms the existing literature.
Recently, titania nanotubes (TNTs) have been extensively studied because both their functional properties and highly controllable morphology make them important building blocks for understanding ...nanoscale phenomena and realizing nanoscale devices. Compared with sol–gel and template-assisted methods, electrochemical anodization is a simple, cost-effective, and low-temperature technique offering additional advantages such as straightforward processing and ease of scale-up. This review focuses on the process modalities and underlying mechanism of electrochemical anodization to achieve a different set of TNTs for a variety of applications. Finally, important applications of TNTs are highlighted including biomedical devices, water purification, and solar cells.
•The everyday affective dimensions of public spaces is a vital but unnoticed aspect of the global war on terror.•Gendered dimension of place and space is central to the theorization and empirical ...exploration of affect.•Gendered geographies of marketplaces enhances our understanding of the affectual ecology of conflict-affected regions.
This paper explores the affective dimensions of the Taliban’s violence in the Swat Valley of Pakistan, with a particular focus on the affective atmosphere of women’s markets there. This paper explores: How is the affective atmosphere of women’s markets in Swat embedded in the structure of feelings that forms the gendered geography of these markets in Swat? How were these culturally embedded places of sociality affected by Taliban’s violence? What effect did Taliban’s violence against women’s markets create in the broader affective economy of fear and violence in Swat? How have these markets revived in the post-conflict Swat? Instead of top-down theorizing of these everyday affective dimensions of the gendered perspective on violence, the paper relies on local voices to explain how women’s markets are perceived and lived during and after violent conflicts in the Swat Valley.
Contemporary semiconducting ceramics, including zinc oxide, find applications in a variety of different fields. Its wurtzite crystal structure can accommodate various dopants, allowing extensive ...engineering to achieve desired properties. Different manufacturing methods such as the sol–gel method, microemulsion technique, chemical vapor deposition (CVD), thermal decomposition, etc. result in different morphologies and yield a range of particle sizes that affect its optical, photocatalytic, and semiconducting properties. Indeed, it has been reported that the introduction of dopants can enhance the dye degradation and photocatalytic properties of ZnO.
Graphic Abstract
Ultraviolet (UV)-induced cationic frontal polymerization has emerged as a novel technique that allows rapid curing of various epoxy monomers upon UV irradiation within a few seconds. In the presence ...of a diaryliodonium salt photoinitiator together with a thermal radical initiator, the cationic ring opening polymerization of an epoxide monomer is auto-accelerated in the form of a self-propagating front upon UV irradiation. This hot propagating front generates the required enthalpy to sustain curing reaction throughout the resin formulation without further need for UV irradiation. This unique reaction pathway makes the cationic frontal polymerization a promising route towards the efficient curing of epoxy-based thermosetting resins and related composite structures. This review represents a comprehensive overview of the mechanism and progress of UV-induced cationic frontal polymerization of epoxy monomers that have been reported so far in literature. At the same time, this review covers important aspects on the frontal polymerization of various epoxide monomers involving the chemistry of the initiators, the effect of appropriate sensitizers, diluents and fillers.
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In establishing electrochemically deposited Al as a structural microdevice, its surface uniformity and mechanical properties such as the hardness are of great importance. In this ...study, an improvement of surface uniformity and mechanical hardening of the film by factors of about 100 and 4, respectively, are reported. Both were associated to the grain size effect, which is attributed to the inclusion of 2-chloronicotinyl chloride additive acting as a grain growth inhibitor in the electrochemical bath. Other important properties, such as the elastic modulus, residual stress and electrical resistivity of the deposit are also studied. This study holds a great potential to pave the way for the utilization of the electrochemically deposited Al in microsystems and related technologies.
The first molybdenum-catalyzed allylic sulfonylation of tertiary allylic electrophiles is described. The method employs a readily accessible catalyst (Mo(CO)
6
/2,2′-bipyridine, both are commercially ...available) and represents the first example of the use of a group 6 transition metal-catalyst for allylic sulfonylation of substituted tertiary allylic electrophiles to form carbon-sulfur bonds. This atom economic and operationally simple methodology is characterized by its relatively mild conditions, wide substrate scope, and excellent regioselectivity profile, thus unlocking a new platform to forge sulfone moieties, even in the context of late-stage functionalization and providing ample opportunities for further derivatization through traditional Suzuki cross-coupling reactions.
The first general example of Mo-catalyzed allylic sulfonylation of tertiary allylic electrophile provides an efficient way to forge sulfone moieties, and providing ample opportunities for further transformation through traditional Suzuki cross-coupling.
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