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241.
Dr. Prakash Kanoo Dr. Ritesh Haldar Dr. Sandeep K. Reddy Dr. Arpan Hazra Dr. Satyanarayana Bonakala Prof. Ryotaro Matsuda Prof. Susumu Kitagawa Prof. Sundaram Balasubramanian Prof. Dr. Tapas Kumar Maji 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(44):15864-15873
An understanding of solid‐state crystal dynamics or flexibility in metal–organic frameworks (MOFs) showing multiple structural changes is highly demanding for the design of materials with potential applications in sensing and recognition. However, entangled MOFs showing such flexible behavior pose a great challenge in terms of extracting information on their dynamics because of their poor single‐crystallinity. In this article, detailed experimental studies on a twofold entangled MOF ( f‐MOF‐1) are reported, which unveil its structural response toward external stimuli such as temperature, pressure, and guest molecules. The crystallographic study shows multiple structural changes in f‐MOF‐1 , by which the 3 D net deforms and slides upon guest removal. Two distinct desolvated phases, that is, f‐MOF‐1 a and f‐MOF‐1 b , could be isolated; the former is a metastable one and transformable to the latter phase upon heating. The two phases show different gated CO2 adsorption profiles. DFT‐based calculations provide an insight into the selective and gated adsorption behavior with CO2 of f‐MOF‐1 b . The gate‐opening threshold pressure of CO2 adsorption can be tuned strategically by changing the chemical functionality of the linker from ethanylene (?CH2?CH2?) in f‐MOF‐1 to an azo (?N=N?) functionality in an analogous MOF, f‐MOF‐2 . The modulation of functionality has an indirect influence on the gate‐opening pressure owing to the difference in inter‐net interaction. The framework of f‐MOF‐1 is highly responsive toward CO2 gas molecules, and these results are supported by DFT calculations. 相似文献
242.
A. Tony Kurissery G. Abraham Rajkumar Venkata Satyanarayana Arvapalli Venkatachalam Pitchumani 《Tetrahedron letters》2017,58(37):3607-3611
A two-step procedure involving acid catalyzed ring opening of spirocyclic epoxides with 2-haloanilines and subsequent palladium-catalyzed intramolecular C–O bond formation to provide spirocyclic-3,4-dihydro-2H-benzo[b][1,4]oxazine derivatives is described. 相似文献
243.
Nadia Benakli Ashwin Satyanarayana Satyanand Singh 《International Journal of Mathematical Education in Science & Technology》2017,48(3):393-427
The goal of this paper is to promote computational thinking among mathematics, engineering, science and technology students, through hands-on computer experiments. These activities have the potential to empower students to learn, create and invent with technology, and they engage computational thinking through simulations, visualizations and data analysis. We present nine computer experiments and suggest a few more, with applications to calculus, probability and data analysis, which engage computational thinking through simulations, visualizations and data analysis. We are using the free (open-source) statistical programming language R. Our goal is to give a taste of what R offers rather than to present a comprehensive tutorial on the R language. In our experience, these kinds of interactive computer activities can be easily integrated into a smart classroom. Furthermore, these activities do tend to keep students motivated and actively engaged in the process of learning, problem solving and developing a better intuition for understanding complex mathematical concepts. 相似文献
244.
Vajja Sadanand Tia Hua Feng Battu Satyanarayana 《International Journal of Polymer Analysis and Characterization》2017,22(7):587-594
In this work, copper nanoparticles were in situ generated in cotton fabrics by simple hydrothermal method. These low-cost nanocomposite fabrics were characterized by scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, thermogravimetric analysis, and antibacterial tests. The presence of spherical nanoparticles was visualized by SEM analysis. FTIR spectra did not show any differences between the peak positions of cotton fabrics and their nanocomposites. The crystallinity of cotton nanocomposites was enhanced by the copper nanoparticles. The cotton nanocomposite fabrics exhibited good antibacterial activity against Escherichia coli bacteria and hence can be considered for medical applications such as wound dressing, surgical aprons, hospital bed materials, etc. 相似文献
245.
Dr. Vishwanath Kalyani Dr. V. S. V. Satyanarayana Dr. Vikram Singh Dr. Chullikkattil P. Pradeep Dr. Subrata Ghosh Dr. Satinder K. Sharma Prof. Kenneth E. Gonsalves 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(5):2250-2258
Two new polyoxometalate (POM)‐based hybrid monomers (Bu4N)5(H)[P2V3W15O59{(OCH2)3CNHCO(CH3)C?CH2}] ( 2 ) and (S(CH3)2C6H4OCOC(CH3)=CH2)6[PVMo10O40] ( 5 ) were developed by grafting polymerizable organic units covalently or electrostatically onto Wells–Dawson and Keggin‐type clusters and were characterized by analytical and spectroscopic techniques including ESI‐MS and/or single‐crystal X‐ray diffraction analyses. Radical initiated polymerization of 2 and 5 with organic monomers (methacryloyloxy)phenyldimethylsulfonium triflate (MAPDST) and/or methylmethacrylate (MMA) yielded a new series of POM/polymer hybrids that were characterized by 1H, 31P NMR and IR spectroscopic techniques, gel‐permeation chromatography as well as thermal analyses. Preliminary tests were conducted on these POM/polymer hybrids to evaluate their properties as photoresists using electron beam (E‐beam)/extreme ultraviolet (EUV) lithographic techniques. It was observed that the POM/polymer hybrid of 2 with MAPDST exhibited improved sensitivity under EUV lithographic conditions in comparison to the MAPDST homopolymer resist possibly due to the efficient photon harvesting by the POM clusters from the EUV source. 相似文献
246.
Digvijay Verma Ashima Anand T. Satyanarayana 《Applied biochemistry and biotechnology》2013,170(1):119-130
Xylanase encoding gene (1,224 bp) from Geobacillus thermodenitrificans was cloned in pET28a (+) vector and successfully expressed in Escherichia coli BL21 (DE3). The deduced amino acid sequence analysis revealed homology with that of glycosyl hydrolase (GH) 10 family with a high molecular mass (50 kDa). The purified recombinant xylanase is optimally active at pH 9.0 and 70 °C with T 1/2 of 10 min at 80 °C, and retains greater than 85 % activity after exposure to 70 °C for 180 min. The enzyme liberates xylose as well as xylooligosaccharides from birchwood xylan and agro-residues, and therefore, this is an endoxylanase. The xylan hydrolytic products (xylooligosaccharides, xylose, and xylobiose) find application as prebiotics and in the production of bioethanol. The xylanase being thermostable and alkalistable, it has released chromophores and phenolics from the residual lignin of pulps, suggesting its utility in mitigating chlorine requirement in pulp bleaching. 相似文献
247.
The purified acidic α-amylase of Bacillus acidicola is a monomer of 66.0 kDa, optimally active at pH 4.0 and 60 °C. The enzyme is Ca2+ independent with T 1/2 for 18 min at 80 °C. The K m, V max, and catalytic efficiency (k cat/K m) of the enzyme are 1.6 mg mL?1, 23.8 μmol mg?1 min?1, and 981 μmol s?1, respectively. Among detergents, Tween 20, 40, and 80 stimulated enzyme activity, whereas sodium dodecyl sulfate and Triton X-100 inhibited even at low concentration. EGTA has not affected the activity, whereas EDTA β-mercaptoethanol, iodoacetic acid, and Dithiothreitol exhibited a slight inhibitory action. Phenylmethanesulfonyl fluoride, N-bromosuccinimide, and Hg2+ strongly inhibited enzyme activity. The experimental activation energy and temperature quotient are 50.12 kJ mol?1 and 1.37. When thermodynamic parameters (ΔH and ΔS) of the enzyme have been determined at different temperatures, ΔG is positive suggesting that the enzyme is thermostable. The enzyme hydrolyzes raw starches, and therefore, the enzyme finds application in raw starch saccharification at sub-gelatinization temperatures that saves energy needed for gelatinization of raw starch at 105 °C. 相似文献
248.
S. Venkateswarlu M. Satyanarayana P. Ravikiran V. Siddaiah 《Journal of heterocyclic chemistry》2013,50(5):1089-1093
We report a facile, one‐pot, three‐component methodology for the synthesis of 8H‐quinazolino[4,3‐b]quinazolin‐8‐ones from commercially available 2‐aminobenzonitriles, triethyl orthoformate, and anthranilic acids/esters/amides in good yields. 相似文献
249.
Aldehydes are transformed into carbamoyl azides/acyl azides by pyridinium chlorochromate in the presence of sodium azide. Comparable oxidations modified with sodium cyanide generate carboxylic acids from simple aliphatic aldehydes whereas conjugated aldehydes are unreactive. 相似文献
250.
B. Venkat Ramulu L. MahendarJ. Krishna A. Gopi Krishna ReddyB. Suchand G. Satyanarayana 《Tetrahedron》2013
A simple and practical method has been developed based on intermolecular [Pd]-catalyzed C–C and an intramolecular [Cu]-catalyzed C–O bond formations for the synthesis of flavans and benzoxepines. Interestingly, the method is amenable for the synthesis of a wide variety of flavans and benzoxepines with dense functionalities on aromatic moieties. Significantly, flavans and benzoxepines are present as core/part-structures in many biologically active natural products. 相似文献