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One of the best ways to prevent the spread of the Covid-19 virus is the adoption of the face mask. Just by wearing a face mask can reduce the risk of contracting the virus by almost 70%. Several government agencies are trying to make wearing a face mask mandatory, this process can be aided by using a face mask detecting software based on the concepts of Artificial Intelligence and Image processing. The proposed model is one that has been built using several deep learning concepts and has been trained on a dataset consisting of more than 11,000 images of faces with and without masks. A SSDNET model is being deployed for face detection, the output of which is passed to a custom made Lightweight CNN for mask detection. The model achieves a high accuracy of ~96% and ~99% on two separate testing datasets. The model will help government agencies and health officials fight the global pandemic.

In the present work, the effect of process parameters on joining of AZ91 Mg alloy and Al6063 aluminum alloy sheets during friction stir welding (FSP) was studied. A successful joint was achieved at 1100 r.p.m. tool rotational speed and 25 mm/min tool travel speed. Combination of tool rotational speed and tool travel speed has observed a profound effect on the material flow mechanisms at the nugget zone. From the microstructural studies, the joint formation was observed as mainly due to mechanical mixing of the materials. The level of metallurgical continuity at the nugget zone was observed as poor and a sharp interface at the joint was noticed. The microhardness measurements across the weld joint also revealed the lack of establishment of a perfect metallurgical bonding. X-ray diffraction analysis of weld zone showed presence of both magnesium and aluminum. Hence from the preliminary observations, it can be understood that the joining of AZ91 Mg alloy and Al6063 alloy can be achieved by FSP; however, complex issues in material mixing still need further investigations. Keywords: Friction stir welding, Dissimilar joints, Magnesium, Aluminum, Nugget zone

A simple easily scalable one-pot route to new phosphonic acid polysilsesquioxanes, PAPSQ, [(O 3/2 SiCH 2 R) x (O 3/2 SiCHR(CH 2 ) 2 SiO 3/2 ) y ] n where R = CH 2 PO 3 H 2 , is described in this paper. Nuclear magnetic resonance (NMR), electron microscopy (SEM), thermogravimetric analysis, nitrogen sorption porosimetry, phosphorus and available acid analysis were used to characterise the new PAPSQ materials. The materials were shown to be very efficient and recyclable mild solid acid catalysts for organic transformations including those relevant to biomass conversion such as esterification, transesterification and dehydration of fructose to the important intermediate 5-hydroxymethylfurfural.

Stability of rebaudioside A, a sweet component of Stevia rebaudiana was studied covering a typical pH range 2.8–4.2 that simulated both relevant and extreme beverage storage conditions. Thus, rebaudioside A was evaluated in mock beverage solutions by simulating formulations used in commercial cola soft drinks (pH 2.8 and pH 3.2), lemon–lime soft drinks (pH 3.8), and root beer soft drinks (pH 4.2) but lacking the flavor components. The mock beverage samples, formulated at ~ 500 mg/l were subjected to various temperature conditions (5, 20, 30, and 40 °C) for 26-weeks at each pH. Samples were analyzed at scheduled intervals throughout the 26-week period for rebaudioside A, its known impurities and degradation products. Experimental results indicated that rebaudioside A yielded six minor degradation compounds whose structural characterization was performed on the basis of 1D ( 1 H, 13 C) and 2D (COSY, HSQC, HMBC) NMR, HRMS, MS/MS spectral data as well as enzymatic and acid hydrolysis studies.

From the commercial extract of the leaves of Stevia rebaudiana, three new diterpenoid glycosides were isolated besides eight known steviol glycosides including stevioside, rebaudiosides A–F and dulcoside A. The structures of the three compounds were identified as 13-[(2-O-β-d-glucopyranosyl-β-d-glucopyranosyl) oxy]-kaur-16-en-18-oic acid-(6-O-β-d-xylopyranosyl-β-d-glucopyranosyl) ester (1), 13-[(2-O-β-d-glucopyranosyl-β-d-glucopyranosyl) oxy]-17-hydroxy-kaur-15-en-18-oic acid β-d-glucopyranosyl ester (2), and 13-[(2-O-β-d-glucopyranosyl-β-d-glucopyranosyl) oxy]-17-oxo-kaur-15-en-18-oic acid β-d-glucopyranosyl ester (3) on the basis of extensive NMR and MS spectral studies. Another known diterpenoid glycoside, 13-[(2-O-β-d-glucopyranosyl-β-d-glucopyranosyl) oxy]-kaur-15-en-18-oic acid β-d-glucopyranosyl ester (4) was also isolated and its complete NMR spectral assignments were made on the basis of COSY, HSQC and HMBC spectral data.

From the commercial extract of the leaves of Stevia rebaudiana, two new minor diterpene glycosides having α-glucosyl linkage were isolated besides the known steviol glycosides including stevioside, steviolbioside, rebaudiosides A-F, rubusoside and dulcoside A. The structures of the two compounds were identified as 13-[(2-O-(3-α-O-d-glucopyranosyl)-β-d-glucopyranosyl-3-O-β-d-glucopyranosyl-β-d-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid β-d-glucopyranosyl ester (1), and 13-[(2-O-β-d-glucopyranosyl-3-O-(4-O-α-d-glucopyranosyl)-β-d-glucopyranosyl-β-d-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid β-d-glucopyranosyl ester (2), on the basis of extensive NMR and MS spectral data as well as chemical studies.

From the commercial extract of the leaves of Stevia rebaudiana , two new diterpenoid glycosides were isolated besides the known steviol glycosides including stevioside, rebaudiosides A–F, rubusoside, and dulcoside A. The structures of the two new compounds were identified as 13-[(2- O -6-deoxy-β- d -glucopyranosyl-β- d -glucopyranosyl)oxy] ent -kaur-16-en-19-oic acid β- d -glucopyranosyl ester ( 1 ), and 13-[(2- O -6-deoxy-β- d -glucopyranosyl-3- O -β- d -glucopyranosyl-β- d -glucopyranosyl)oxy] ent -kaur-16-en-19-oic acid β- d -glucopyranosyl ester ( 2 ), on the basis of extensive NMR and MS spectral data as well as chemical studies.

Co-SBA-15 catalysts were synthesized by direct synthesis and post-synthetic impregnation methods at two different loadings of Co viz., 1.2 and 2 wt%. The structure of SBA-15 was found to remain intact even after the incorporation of Co in either of the two methods of catalyst preparation, which was confirmed by low-angle XRD. The existence of Co2+ species were confirmed by characteristic absorption bands of Co in the UV–vis spectra and XPS results. The encapsulation of Co in SBA-15 was found to be highly advantageous in yielding significant amounts of the desired products viz., cyclohexanone and cyclohexanol in the oxidation of cyclohexane in liquid phase without using any solvent under moderate pressure of O2 at 433 K. The catalysts showed high turn over numbers towards the oxidation of cyclohexane to cyclohexanone and 2%CoSYN (2 wt% Co-SBA-15) catalyst showed a maximum of 9.4% conversion of cyclohexane and 78% selectivity towards the formation of cyclohexanone.

Two attempts to explain the phenomenon of business cycles – the former by Schumpeter and the latter by Kydland and Prescott, take polemic positions on role of human agency in bringing about technological change. Schumpeter considers technological change as the consequence of decisions of entrepreneurs who search for “new ways of doing things”. The Real Business Cycle (RBC) theory proposed by Kydland and Prescott posits that technological changes occur as random shocks to economic system. Technology shocks imply that entrepreneurs/managers have hardly any role to play in technological change, and suggest a deterministic and limited role for managers. This provides a research setting to test these competing hypotheses as the null and alternative. We test the technology shock hypothesis with time-series data on productivity from Indian and US sugar industries. Results from our study reject the technology shock hypothesis and implies pre-eminence of managerial discretion and strategic choice.

The synthesis of (±)- trans -2-[3-methoxy-4-(chlorophenylthioethoxyphenyl)-5-cyanophenyl]-5-(3,4,5-trimethoxyphenyl)tetrahydrofuran from commercially available acetovanillone and 3,4,5-trimethoxybenzaldehyde is described.