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The severe outbreak of respiratory coronavirus disease 2019 has increased the significant demand of respiratory mask and its use become ubiquitous worldwide to control this unprecedented respiratory pandemic. The performance of a respiratory mask depends on the efficiency of the filter layer which is mostly made of polypropylene melt blown non-woven (PP-MB-NW). So far, very limited characterization data are available for the PPE-MB-NW in terms to achieve desired particulate filtration efficiency (PFE) against 0.3 µm size, which are imperative in order to facilitate the right selection of PP-MB-NW fabric for the development of mask. In present study, eight different kinds of PP-MB-NW fabrics (Sample A–H) of varied structural morphology are chosen. The different PP-MB-NW were characterized for its pore size and distribution by mercury porosimeter and BET surface area analyzer was explored first time to understand the importance of blind pore in PFE. The PP-MB-NW samples were characterized using scanning electron microscopy so as to know the surface morphology. The filtration efficiency, pressure drop and breathing resistance of various PP-MB-NW fabric samples are investigated in single and double layers combination against the particle size of 0.3, 0.5 and 1 µm. The samples which are having low pore dia, high solid fraction volume, and low air permeability has high filtration efficiency (> 90%) against 0.3 µm particle with high pressure drop (16.3–21.3 mm WC) and breathing resistance (1.42–1.92 mbar) when compared to rest of the samples. This study will pave the way for the judicial selection of right kind of filter layer i.e., PP-MB-NW fabric for the development of mask and it will be greatly helpful in manufacturing of mask in this present pandemic with desired PFE indicating considerable promise for defense against respiratory pandemic.

An ocean circulation model, Nucleus for European Modelling of the Ocean (NEMO version 3.6) is customized to run at high-resolution over a regional domain [30oE-105oE; 20oS-30oN] in the Indian Ocean...

The performance of vertical parameterization schemes, namely, turbulent kinetic energy (TKE) and K-profile parameterization (KPP), is evaluated over the domain [30E-120E; 20S-30N] in the Indian Oce...

The solutions of Mg(NO3)2, Al(NO3)3, and (NH4)2CO3 were mixed at pH 8 and then heated at 95 °C for 4 h, aged at room temperature for 16 h, and calcined at 650 °C for 4 h to obtain magnesium aluminate nanoparticles. The obtained materials exhibited spinel structure with the particle size being 6 to 26 nm. The nanoparticles demonstrated type IV nitrogen adsorption isotherm, typical of mesoporosity with a surface area of 325 m2/g. They were utilized for studies on chemical detoxification of deadly chemical warfare agents such as sarin and soman. Our results showed that the magnesium aluminate nanoparticles effectively decontaminated more than 99% of sarin and soman within 8–10 min when used at a ratio of 1:50–60% w/w.

An effective decontamination methodology based on nucleophilic non-aqueous decontaminant has been developed against chemical weapons sulfur mustard and soman. This new formulation consists of non-aqueous solution of 2-aminoethanol (60%, w/v), potassium hydroxide (2%, w/v), and N-methyl-2-pyrrolidone (38 %, w/v) and detoxified more than 99 % of sulfur mustard and soman within a period of 30 min at -35 °C. It was found to be operable over a wide range of temperatures starting from -35 °C to +55 °C without losing its fluidity and detoxicant efficiency at sub-zero temperatures promising hassle-free application against chemical weapons. It degrades sulfur mustard to divinyl sulfide and 2-chloroethyl vinyl sulfide and converted soman into O-pinacolyl O’-(2-amino) ethyl methylphosphonate, which are relatively non toxic to humans. This formulation is environmentally benign, relatively non corrosive and has an improved capability to dissolve and decontaminate chemical weapons within 15 minutes at ambient conditions. This approach paves the way for efficient and rapid decontamination platform for chemical weapons and holds considerable promise for field application in near future.

Herein, we demonstrate a nanocomposite material Eu/ZnO/pPy for enhanced performance in photoelectrocatalytic degradation of chemical warfare agent sulphur mustard (SM) at ambient conditions which is growing concern of the Scientific Community amidst the current climate of terrorism. Eu/ZnO/pPy was electrochemically prepared on Au electrode at ambient conditions and was used for electrocatalytic reductive elimination of chloride from SM and results indicated one electron involvement process for the cleavage of the carbon-chloride bond. Surface morphology of Eu/pPy, ZnO/pPy and Eu/ZnO/pPy composites were characterized by SEM and confirmed the formation of the nanoparticles and nanorods on the modified electrode which leads to provide more surface area for the reductive elimination reaction. The elemental composition, functional groups and phase of materials on the modified electrode were deduced using EDX, Raman spectroscopy and XRD, respectively. Eu/ZnO/pPy/Au electrode was utilized for the photoelectrocatalytic degradation of SM as it exhibit excellent electrocatalytic activity and degradation products were analyzed by GC-MS. In the reductive elimination of SM, the following parameters were deduced (i) heterogeneous rate constant (0.127 s-1), (ii) transfer coefficient (0.32) and (iii) number of electron involved (1.0). The enhanced photoelectrocatalytic capability of this nanocomposite could serve as a novel and promising catalyst in defence and environmental applications.

A mechanistically unprecedented approach for the formation of tertiary amides from N,N-dialkylchlorothiophosphoramidates and aldehydes has been developed. The reaction occurred via the activation of aldehydes with N,N-dialkylchlorothiophosphoramidates followed by amidation with dialkylamine pendent of the same phosphoramidate.

The application of pervaporation (PV) to the removal of volatile organic from aqueous solutions has become very interesting in the last few years. It is caused by the increasing level of compounds, such as petrochemical solvents (benzene, toluene, and xylenes) or chlorinated solvents (trichloroethylene or tetrachloroethylene), which are polluting the natural environment. In this work, effects of polyimide (PI) (prepared by direct polycondensation of dianhydride and diamine followed by thermal cyclization of polyamic acid) filler on PV properties of poly(dimethyl siloxane) (PDMS) have been studied. PDMS membrane filled with PI was used for the separation of benzene (Bz) and toluene (Tol) from the diluted aqueous solution and the results were compared with the neat PDMS membrane of similar thickness. The PDMS-PI membrane showed normalized flux (J′) upto 1.2 kg μm/m2h for Bz and 1.48 kg μm/m2h for Tol and selectivity of organics varies from 7.3 to 3.2 for Bz and 8.9 to 2.8 for Tol with increasing concentration of organics. Concentration of PI filler in PDMS varied 5–25% w/w. PI filler increases thermal as well as mechanical stability of filled PDMS membranes. PDMS membrane filled with 25% PI was chosen for the pervaporation studies. The membranes were characterized by FTIR, thermogravimetric analyser and scanning electron microscopy. The mechanical strength of PDMS filled with 25% w/w PI (SPI-25) membrane was found to be 2.7 MPa. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

A very simple, environmentally benign, cost-effective, and efficient synthesis of disulfides from thiols using silica–PCl5/NaNO2 in aqueous medium has been described. The reaction was found to occur rapidly under mild conditions, and disulfides were obtained easily through a simple workup.

A series of soluble polyamides were synthesized by direct polycondensation of the 5-tert-butyl isophthalic acid with different diamines. Solution (20%) of the polymers in suitable solvents was used to cast the membranes. The membranes showed selectivity toward the benzene (Bz) in a mixture of Bz/water (H2O). Water affinity of the membrane was found to be lower than that of Bz. The polyamide incorporating hexafluoro isopropylidene moiety was promising for the dehydaration of Bz and breaking of Bz/H2O azeotrope. The polymers exhibited inherent viscosities, ranging from 0.40 to 0.92 dL/g and 10% weight loss in synthetic air up to 474°C. Glass transition temperature measured by DSC and DMA reached up to 258°C. The membranes were pale yellow in appearance having tensile strength up to 85 MPa, modulus of elasticity up to 2.6 GPa, and elongation at break up to 9.5%, depending upon the exact repeating unit structure. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

A novel thionation protocol for carbonyl compounds, with the system PSCl3/H2O/Et3N has been discovered. Clean, rapid, and efficient synthesis of a variety of thiocarbonyl compounds such as thioamides, thiolactams, thioketones, thioxanthones, and thioacridone can be achieved through this simple and convenient method under solventless condition with microwave irradiation.

A new solid supported reagent, silica–PSCl3, has been developed for deoxygenation of sulfoxides. With this reagent, conversion of sulfoxides to sulfides occurred cleanly and efficiently at room temperature. Facile isolation of the product was achieved by simple filtration of the by‐products without any extensive workup.

Poly(vinyl acetal) PVAc was synthesized by the acid-catalyzed acetalisation of poly(vinyl alcohol). Three different morphologically modified variants of the polymer were prepared by the addition of supramolecules; namely α and β cyclodextrins (CD) and butyl calixerene (calix) to the PVAc sol. 20% (w/v) of the solution of the polymers in tetrahydrofuran (THF) was used to cast the membranes. These membranes were characterized using spectroscopic and thermoanalytical techniques, and also tested for their chemical resistance and mechanical strength. The pervaporative behaviour of modified membranes vis-a-vis PVAc for the separation of a wide composition of benzene (Bz)/cyclohexane (Chx) mixtures was evaluated. Addition of αCD or calix to PVAc reduced the overall flux while dispersion of βCD favoured an enhanced flux especially in the Bz-lean and azeotropic region.

Cellulose membrane produced by bacterial Acetobacter xylinum was deproteinated and investigated for pervaporative separation of aqueous organic mixtures. The permeate flux, selectivity, pervaporation separation index (PSI), solubility and degree of sorption were studied as a function of increasing concentration of organics in the feed. The membrane was found highly selective to water; highest selectivity [αp = 186] was obtained for a mixture of trihydric alcohol viz. glycerol (Gly) with 40% (v/v) water. The binary system of monohydric alcohol viz. ethanol (EtOH) and water (40% (v/v)) showed the lowest selectivity [αp = 12] but the highest pervaporative flux of 614 gm−2 h−1 at 35 °C which further increased to 1429 gm−2 h−1 at 75 °C. However, selectivity decreased to 1.3 with the increase in temperature. The pervaporation behaviour was interpreted in terms of sorption and diffusivity of the organics, which in turn, was influenced by the extent of their hydrogen bonding with the cellulose units in the membrane and the plasticization induced by the permeating water present in the binary mixture. Substantially high pervaporative separation index (PSI) of the order of 103–104 gm−2 h−1 and comparatively lower energy of activation (Ej) of 10 kJ/mol is indicative of the pervaporative potential of the bacterial cellulose membrane (BCM) in the separation of aqueous binary mixtures.

The pervaporative (PV) performance with respect to the separation of ethanol/water (EtOH/H2O) azeotrope was assessed for a bacterial cellulose membrane (BCM) impregnated with chitosan (CTSN), designated as CTSN–BCM. The PV potential of CTSN–BCM was compared with that of parent polymers and also with the blends of CTSN with poly(vinyl alcohol) (PVA). The blends and CTSN–BCM were characterized using spectroscopic and thermoanalytical techniques, and also tested for their mechanical strength and sorption of EtOH/H2O mixtures. While PVA and the blends tend to dissolve at higher concentration of water, CTSN–BCM was found to be intact over the entire composition range. When evaluated against pervaporation of 95:5 w/w EtOH/H2O azeotrope at 24 ± 1 °C; CTSN–PVA (1:1) blend showed comparatively higher selectivity (22.0) but a poorer flux (1.7 kg μm m−2 h−1). The flux was significantly higher (42.8 kg μm m−2 h−1) in CTSN–BCM and selectivity (∼10) was at par with PVA. The temperature dependence of selectivity and flux through CTSN–BCM was also investigated. Substantially high pervaporative separation index (PSI) of the order of 350 kg μm m−2 h−1 and low energy of activation of 10 kJ/mol is indicative of the potential of CTSN–BCM in the pervaporative separation of EtOH/H2O azeotrope.

The heart of a chemical sensor based on bulk or surface acoustic wave devices is a polymer-coated piezoelectric substrate that selectively sorbs and concentrates the target analyte vapors. The development of such sensors often necessitates the screening and evaluation of suitable polymeric interface materials meeting the specified sensitivity and selectivity toward the analytes of interest. The magnitude and dynamics of sorption–desorption of the vapors in the polymer and the extent of polymer–vapor interactions largely determine the performance of a sensor. The standard protocol used for the purpose is rather tedious, involving the generation and calibration of individual analyte vapors, with stringent control on temperature, humidity, and test parameters. This article outlines four different alternative techniques based on mass uptake of the analyte vapors, on its partitioning in polymers, or both, which in combination can determine the characteristics of an interface material used for coating a piezoelectric substrate in acoustic wave-based chemical sensors. These methods were applied to poly(ethylene maleate), a representative interface material. The analytes ranged from volatile organic chemicals to sarin—a chemical warfare agent—and its simulant, dimethyl methylphosphonate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3428–3432, 2004

Poly(vinyl alcohol) (PVA) was chemically modified by acid-catalysed acetalisation, resulting in the formation of poly(vinyl acetal) (PVAc). The addition of a molecular recognition compound, namely, O , O -bis(diethoxyphosphoryl)- tert -butyl calixarene (calix) to the PVA sol, yielded the morphologically modified membranes, designated as PVA–calix. These membranes were characterised using spectroscopic and thermoanalytical techniques, and also tested for their chemical resistance, mechanical strength and pervaporative behaviour towards benzene (Bz)/cyclohexane (Chx) mixtures. The polymers were found to be selective towards Bz. When evaluated against pure Bz and Chx at 27±1 °C; PVA–calix showed an ideal selectivity tending towards infinity but a poor flux (5.9 kg μm/(m 2 h)) for Bz. The flux of Bz was significantly higher in PVAc and increased from 20 kg μm/(m 2 h) for 20% (v/v) Bz/Chx mixture to 65.8 kg μm/(m 2 h) for pure Bz. The swelling index also increased with the increasing concentration of Bz in the feed. Pervaporation in PVAc was thus sorption-controlled. The sorption isotherms for the pure components in PVAc were also obtained using an automated sorption analyser based on the principle of mass relaxation of the polymer accompanying vapour sorption. The high interaction of PVAc with Bz was interpreted in terms of solubility parameters and free volume in the polymer.

A mechanistically unprecedented approach for the formation of tertiary amides from N,N-dialkylchlorothiophosphoramidates and aldehydes has been developed. The reaction occurred via the activation of aldehydes with N,N-dialkylchlorothiophosphoramidates followed by amidation with dialkylamine pendent of the same phosphoramidate.

A simple and convenient one-pot strategy for the prepa ration of thioflavones from 1,3-diketones is described. Cyclodehydration of a range of β-diketones and thionation of the resulting flavones was achieved using thiophosphoryl chloride (PSCl 3 ) which serves as both a catalyst and thionating agent.

In the presented synthesis of the compounds (II) and (IV) aryl nitriles are the intermediates.

The reaction is conducted using an environmentally benign and simple protocol which leads to easily isolable products.

This is the first report of a facile synthesis of thiazolines and thiazines from a self-catalyzed, water assisted tandem S-alkylation-cyclodeamination reaction of thioamides/haloamines. The reaction is clean and efficient with simple product work-up, and is applicable to a variety of substrates.

A simple one-pot procedure allows the preparation of the title compounds via intermediate flavones.

substituted thioamides starting from acyl halides and amines is an attractive method as it allows an easy introduction of diverse building blocks for constructing desired thioamides. This is a two step procedure. For avoiding a lengthy separation process and purification of intermediate, one-pot preparation techniques are highly preferred. The potential of one-pot procedure is enhanced if applied with microwave heating under solvent-free condition

A very simple, environmentally benign, cost-effective, and efficient synthesis of disulfides from thiols using silica–PCl5/NaNO2 in aqueous medium has been described. The reaction was found to occur rapidly under mild conditions, and disulfides were obtained easily through a simple workup.

N-Substituted thioamides were accessed from ketoximes by utilising PSCl3 as a uniquely capable reagent to induce Beckmann rearrangement as well as to capture the intermediate nitrilium ion.

A convenient, highly efficient, safe microwave-mediated Salkylation of O,O’-dialkyl thiophosphate has been reported. Clean and rapid S-alkylation of thiophosphates can be achieved by irradiating a mixture of dialkylthiophosphate salt and alkyl halide under microwave for a brief period. Alkylation occurs exclusively at sulfur to provide S-alkylated products. Through a simple workup, pure compounds have been obtained easily in good yields.

A novel thionation protocol for carbonyl compounds, with the system PSCl3/H2O/Et3N has been discovered. Clean, rapid, and efficient synthesis of a variety of thiocarbonyl compounds such as thioamides, thiolactams, thioketones, thioxanthones, and thioacridone can be achieved through this simple and convenient method under solventless condition with microwave irradiation.

A new solid supported reagent, silica–PSCl3, has been developed for deoxygenation of sulfoxides. With this reagent, conversion of sulfoxides to sulfides occurred cleanly and efficiently at room temperature. Facile isolation of the product was achieved by simple filtration of the by‐products without any extensive workup.

This is the first report of a facile synthesis of thiazolines and thiazines from a self-catalyzed, water assisted tandem S-alkylation-cyclodeamination reaction of thioamides/haloamines. The reaction is clean and efficient with simple product work-up, and is applicable to a variety of substrates.

An efficient method for the amidation and esterification of aldehydes utilizing hydrogen peroxide as an oxidant has been developed. Cyclic amines and primary alcohols selectively reacted with aromatic aldehydes under mild conditions to yield the corresponding amides and esters.