A Novel Geometry Multi-Stage Depressed Collector for the Efficiency Enhancement of Space Traveling Wave Tubes

A novel geometry of a multi-stage depressed collector with four stages has been designed for Ka-band space traveling wave tube. The inner structure of each electrode of the collector has been provided with a single-step corrugation of a positive slope followed by a negative slope. The performed simulation predicts that the proposed collector has 7 % more efficiency, less back streaming of electrons and lower weight as compared to the collector with conventional geometry. Additional features of this collector include inherent secondary electron trapping mechanism and better power handling capabilities. Above properties of the proposed collector makes it suitable for space applications.     

Comparative analysis of chipping mechanics of float glass during rotary ultrasonic drilling and conventional drilling: For multi-shaped tools

Float glass has immense applications such as sensor glass, micro-processor glass and decorative glass; because of its exceptional wear resistance, chemical and thermal characteristics. Nevertheless, researchers are still bearing decisive issues, which affect its application. These issues are profile inaccuracy and chipping because of its poor machining characteristics and hence high precision machining. The objective of the present study is to condemn the chipping related hindrances while using multi-shaped diamond abrasive tools to create blind holes. The tools, which applied, are named as hollow abrasive tool, pinpointed conical tool, flat cylindrical tools and concave circular tool. The experimental trials were performed by rotary ultrasonic drilling (RUD) and CNC conventional drilling (CD). The actual industrial conditions and parameters were considered throughout the experimentation. Physics behind the formation of chipping on hole periphery by RUD and CD are revealed. In addition, individual mechanisms of multi-shape tools with respect to chipping are analyzed. The results show that RUD process has attained the smallest measurement of chip radial distance as compared to CD for all types of tool. Finally, the concave circular tool is found as the best tool particularly to get least chip radial distance during drilling i.e. 0.1145?mm.     

Synthesis and in vitro Study of Artemisinin/Synthetic Peroxide-Based Hybrid Compounds against SARS-CoV-2 and Cancer

The newly emerged severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cause life-threatening diseases in millions of people worldwide, in particular, in patients with cancer, and there is an urgent need for antiviral agents against this infection. While in vitro activities of artemisinins against SARS-CoV-2 and cancer have recently been demonstrated, no study of artemisinin and/or synthetic peroxide-based hybrid compounds active against both cancer and SARS-CoV-2 has been reported yet. However, the hybrid drug's properties (e. g., activity and/or selectivity) can be improved compared to its parent compounds and effective new agents can be obtained by modification/hybridization of existing drugs or bioactive natural products. In this study, a series of new artesunic acid and synthetic peroxide based new hybrids were synthesized and analyzed in vitro for the first time for their inhibitory activity against SARS-CoV-2 and leukemia cell lines. Several artesunic acid-derived hybrids exerted a similar or stronger potency against K562 leukemia cells (81–83 % inhibition values) than the reference drug doxorubicin (78 % inhibition value) and they were also more efficient than their parent compounds artesunic acid (49.2 % inhibition value) and quinoline derivative (5.5 % inhibition value). Interestingly, the same artesunic acid-quinoline hybrids also show inhibitory activity against SARS-CoV-2 in vitro (EC₅₀ 13–19 μm ) and no cytotoxic effects on Vero E6 cells (CC₅₀ up to 110 μM). These results provide a valuable basis for design of further artemisinin-derived hybrids to treat both cancer and SARS-CoV-2 infections.     

Zinc blende GaAsSb nanowires grown by molecular beam epitaxy

We report the growth of GaAsSb nanowires (NWs) on GaAs(111)B substrates by Au-assisted molecular beam epitaxy. The structural characteristics of the GaAsSb NWs have been investigated in detail. Their Sb mole fraction was found to be about?25%. Their crystal structure was found to be pure zinc blende (ZB), in contrast to the wurtzite structure observed in GaAs NWs grown under similar conditions. The ZB GaAsSb NWs exhibit rotational twins around their [111]B growth axis, with twin-free segments as long as 500?nm. The total volumes of GaAsSb segments with twinned and un-twinned orientations, respectively, were found to be equal by x-ray diffraction analysis of NW ensembles.     

Efficacy of application of vegetable seed oils as grain protectant against infestation by Callosobruchus chinensis and its effect on milling fractions and apparent degree of dehusking of legume-pulses

The solvent extracted vegetable seed oils of Cucurbitaceae family viz. Bitter gourd (Momordica charentia), Small bitter gourd (Momordica dioica), Bottle gourd (Lagenaria siscraria) and Ridge gourd (Luffa acutangula) were evaluated as grain protectant against callosobruchus chinensis on the stored legume-pulse grains. All the vegetable seed oils were found effective as legume-pulse grain protectant, which provided, negligible weight loss at the oil-application rate of 6-8 mL/kg in legume-pulse grain after 60 days storage at laboratory conditions. The milling yield and degree of dehusking gets improved after the oil application. The use of solvent extracted Small bitter gourd seed oil at the level of 6-8 mL/kg of legume-pulse grain sample resulted in the improved apparent degree of dehusking from 40.0 to 72.59, 59.88 to 92.44, 63.39 to 87.50 and 57.0 to 79.43 for Pigeonpea (Canjanus cajan), Chickpea (Cicer arietinum), Urdbean (Phaseolus mungo) and Mungbean (Phaseolus radiatus), respectively.     

Multi-Objective Optimization During Magnetic Field Assisted ECDM of Alumina-Zirconium Dioxide Ceramic Composite using Battle Royale Optimization

Alumina-Zirconium dioxide (Al₂O₃-ZrO₂) Ceramic Composite Material (CCM) is specifically known for its enhanced mechanical and corrosion resistance properties and is widely used as raw material for mechanical parts like, pump components, die inserts, bearings, etc. As a result, industrialists are searching for an efficient method for machining this Al₂O₃-ZrO₂ material. In this regard, a hybrid unconventional machining process called Electrochemical Discharge Machining (ECDM) is adapted to analyze the machinability of Al₂O₃-ZrO₂ CCM. Besides, to ensure the efficiency of the ECDM process, a magnetic field is also given to the tool electrode during this study to improve the Material Removal Rate (MRR) of the ECDM machine. The experiment is designed using Response Surface Methodology (RSM) by changing the magnitudes of input controls, namely Electrolytic Concentration (EC), Inter-electrode Gap (IEG) and Applied Voltage (AV). Moreover, a novel hybrid machine learning optimization strategy called Deep Belief Network based Battle Royal Optimization (DBN-BRO) algorithm is developed to predict and optimize the ECDM process. Finally, the optimum results are perceived from 55 V AV, 22.727% EC and 40.909 mm IEG input levels. The proposed method shows less than 0.6207 Root Mean Square Error (RMSE) and tools nearly 80 iterations for optimizing the results.     

Extraction and Analysis of Recovered Silver and Silicon from Laboratory Grade Waste Solar Cells

Silicon - In the present work, a new process is reported to recover metallic contacts and wafer from the crystalline silicon solar cell through chemical etching. 2 M KOH was used as an...