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21.
22.
Bisphenol-A polycarbonate films were irradiated with 86 MeV swift heavy nickel ions at varying fluences, ranging from 1 × 1011 to 1 × 1013 ions cm?2, under vacuum at room temperature, to analyze the induced electrical and thermal modifications. AC conductivity measurements and UV-visible spectroscopy, Fourier transform infra-red (FTIR) spectroscopy, thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) techniques were applied to analyze the changes. A significant, exponential increase in conductivity at higher frequency was observed with the increase of nickel ion fluence. UV-visible analysis corroborated the results of the AC conductivity measurement, revealing the increase in size of the carbon clusters embedded in the polymer network, with the increase of heavy ion fluence. FTIR analysis revealed the formation of alkene and alkyne end groups at higher doses, which further supported the suggestion that the variation in electrical properties induced by the ion irradiation of the polymer was due to development of a carbonaceous phase inside the polymer due to the irradiation. Thermal analysis, i.e., TGA and DSC patterns, showed that chain-scission was the leading phenomena in the heavy ion-irradiated polycarbonate samples, resulting in degradation of their thermal stability. 相似文献
23.
Subhrakant Jena Kiran Devi Tulsiyan Dr. Rajiv K. Kar Dr. Hemanta K. Kisan Dr. Himansu S. Biswal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(13):4373-4383
Designing a potential protein–ligand pair is pivotal, not only to track the protein structure dynamics, but also to assist in an atomistic understanding of drug delivery. Herein, the potential of a small model thioamide probe being used to study albumin proteins is reported. By monitoring the Förster resonance energy transfer (FRET) dynamics with the help of fluorescence spectroscopic techniques, a twofold enhancement in the FRET efficiency of 2-thiopyridone (2TPY), relative to that of its amide analogue, is observed. Molecular dynamics simulations depict the relative position of the free energy minimum to be quite stable in the case of 2TPY through noncovalent interactions with sulfur, which help to enhance the FRET efficiency. Finally, its application is shown by pairing thiouracils with protein. It is found that the site-selective sulfur atom substitution approach and noncovalent interactions with sulfur can substantially enhance the FRET efficiency, which could be a potential avenue to explore in the design of FRET probes to study the structure and dynamics of biomolecules. 相似文献
24.
Caroline K. Williams Amir Lashgari Nilakshi Devi Marcus Ang Ashwin Chaturvedi Pranita Dhungana Prof. Jianbing Jimmy Jiang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(20):6240-6246
In this work, the electrocatalytic reduction of dichloromethane (CH2Cl2) into hydrocarbons involving a main group element-based molecular triazole-porphyrin electrocatalyst H2PorT8 is reported. This catalyst converted CH2Cl2 in acetonitrile to various hydrocarbons (methane, ethane, and ethylene) with a Faradaic efficiency of 70 % and current density of −13 mA cm−2 at a potential of −2.2 V vs. Fc/Fc+ using water as a proton source. The findings of this study and its mechanistic interpretations demonstrated that H2PorT8 was an efficient and stable catalyst for the hydrodechlorination of CH2Cl2 and that main group catalysts could be potentially used for exploring new catalytic reaction mechanisms. 相似文献
25.
Arumugam Vasudevan Gayathri Devi Gurusamy Rajkumar Kathiresan Sakthipandi Venkatachlam Rajendran Nallaiyan Rajendran Mani Rajkumar 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):1434-1449
Abstract Phosphate-based bioactive glasses and their glass ceramics for 47P2O5– (30.5)CaO–(22.5 ? x)Na2O–xZrO2 for different ZrO2 contents (x = 0, 1.5, 3.0, 4.5, and 6.0 mol%) were prepared through melt quenching and controlled heat treatment procedures. The amorphous nature of glasses and the presence of crystalline phases in glass ceramics were studied by means of X-ray diffraction (XRD) studies. The density, molar volume, ultrasonic velocities, attenuation, elastic constants, and microhardness of glass and glass ceramics were used to study the structural changes. The formation of hydroxyapatite layer on the surface of glasses and glass ceramics after immersion in simulated body fluid (SBF) was explored through XRD, Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) analyses. The results indicate that the added ZrO2 increases the crosslink density of glasses, resulting in network stability, and also induces the formation of an apatite layer on the surface of glasses. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
26.
Jai Devi Suman Kumari R. Malhotra 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5):587-597
Abstract The Schiff bases derived from the condensation of 2-aminobenzothiazole derivatives and 2-hydroxy-3-methoxybenzaldehyde and their silicon(IV) complexes with the general formula R2Si(L)Cl (R = Et, Bu, Ph, L = 2-(2-hydroxy-3-methoxy) benzylideneaminobenzo-thiazole) have been synthesized. These complexes have been characterized by elemental analysis, molar conductance, and spectroscopic studies including IR and NMR (1H, 13C, and 29Si) spectroscopy. The analytical data suggest trigonal bipyramidal geometry around the silicon atom in the resulting complexes. The ligands and their organosilicon complexes have also been evaluated for in vitro antimicrobial activity against bacteria (Staphylococcus aureus, Bacillus subtilis, and Escherichia coli) and fungi (Aspergillus niger and Candida albicans). The complexes were found to be more potent as compared to the ligands. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
27.
Aarti Gupta Pragati Devi Priyanka Chaudhary Dharma Kishore 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):808-821
Abstract The synthetic potential of 2,3,4,5-tetrahydrobenzo[b] [1,5]thiazepine-1,1,4-trione-2-carbohydrazide (5) which resulted from ethyl-4-oxo-2,3,4,5-tetrahydrobenzo[b] [1,5]thiazepine-2-carboxylate (3), on its oxidation with H2O2/AcOH followed by treatment with NH2NH2.H2O, was exploited to provide an access to 2-triazolo, 2-oxadiazolo, and 2-pyrazolo substituted derivatives of 1,5-benzothiazepin-4-oxo-1,1-dioxides (6–10), respectively. 相似文献
28.
The viscosity of hydroxypropyl cellulose (HPC) solution with or without an additive has been measured continuously as a function of temperature with the help of a vibro-viscometer. The viscosity of the polymer solution showed a gradual decrease initially with increase in temperature until a particular point beyond which there was a sharp decrease in the viscosity, which coincided with the clouding of the solution. The cloud point temperature (CP) of the polymer solution was determined from the first derivative plot of viscosity vs. temperature. Effect of addition of an electrolyte or a surfactant on the CP of HPC solution has also been studied. While a decrease in CP of HPC solution in presence of fluoride, chloride, or bromide ions was observed, presence of iodide or thiocyanide ions led to an increase in the CP. However, presence of an ionic surfactant initially lowered the CP but beyond a particular surfactant concentration a sharp increase in cloud point was observed due to interaction of the surfactant with the polymer. The results suggest that surfactants with longer hydrophobic tail or more hydrophobic groups have more affinity for HPC. 相似文献
29.
Abstract Immobilization of pepsin on crosslinked resinous materials SRF (salicylic acid-resorcinol-formaldehyde), Amberlite IRA-400, and poly-(vinyl alcohol) is reported. Enzyme concentration, pH of the coupling medium, and nature and concentration of crosslinking agents were optimized for the better retention of activity of immobilized pepsin. The immobilized systems were characterized through pH, thermal, and storage stabilities. Michaelis constant (K m) and maximum reaction velocity (V m) for the free and immobilized enzymes were calculated from Lineweaver-Burk plots. Effect of temperature on enzyme activity was studied, and the thermoinactivation constant (K ti) and energy of activation (E a) for free and immobilized enzymes were also calculated. The immobilized pepsin was used in a continuous fluidized bed reactor for the study of clotting of skimmed milk. Rate of coagulation was considerably high for the treated milk sample at 50°C and pH 6–6.2. 相似文献
30.
Abstract Macroazoinitiator (MAI) was prepared from hydroxyl‐terminated polybutadiene (HTPB) and 4,4′‐azobis‐4‐cyanopentanoic acid by direct polycondensation in the presence of 1‐methyl‐2‐chloropyridinium iodide at room temperature. This MAI used for block copolymerization of AAm at 60°C gave the best results in chloroform but the formation of a crosslinked product could not be ruled out in dioxane. It was inferred that for production of a linear block copolymer, homogeneous reaction mixture was required. The resulting products were characterized by spectral studies IR and NMR, viscosity measurements. Distinct phase segregation of hydrophobic and hydrophilic blocks was evident through DSC analysis. 相似文献