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51.
Swati Chauhan Priyanka Chaudhary Adesh Kumar Singh Pratibha Verma Vandana Srivastava Jeyakumar Kandasamy 《Tetrahedron letters》2018,59(3):272-276
A simple and efficient method for the dimerization of primary thioamides into 1,2,4-thiadiazoles using tert-butyl nitrite is described. The optimized condition was also found to be suitable for the dimerization of benzoselenoamides into 1,2,4-selenadiazoles. All the reactions proceed smoothly at room temperature and gave the desired products in excellent yields in a short span of time. 相似文献
52.
Tek Chand Bhalla Vijay Kumar Virender Kumar Neerja Thakur Savitri 《Applied biochemistry and biotechnology》2018,185(4):925-946
Nitrile metabolizing enzymes, i.e., aldoxime dehydratase, hydroxynitrile lyase, nitrilase, nitrile hydratase, and amidase, are the key catalysts in carbon nitrogen triple bond anabolism and catabolism. Over the past several years, these enzymes have drawn considerable attention as prominent biocatalysts in academia and industries because of their wide applications. Research on various aspects of these biocatalysts, i.e., sources, screening, function, purification, molecular cloning, structure, and mechanisms, has been conducted, and bioprocesses at various scales have been designed for the synthesis of myriads of useful compounds. This review is focused on the potential of nitrile metabolizing enzymes in the production of commercially important fine chemicals such as nitriles, carboxylic acids, and amides. A number of opportunities and challenges of nitrile metabolizing enzymes in bioprocess development for the production of bulk and fine chemicals are discussed. 相似文献
53.
M.I. Adamovich M.M. Agarwall Y.A. Alexandrov N.P. Andreeva S.K. Badyal E.E. Basova K.B. Bhalla A. Bhasin V.S. Bhatia V. Bradnova 《The European Physical Journal A - Hadrons and Nuclei》1999,6(4):421-425
The nuclear emulsion was exposed at CERN by the lead projectile at 160 A GeV. The angles between any pair of fragments with Z = 2-4 have been measured in the emulsion plane for the events which did not contain heavy fragments. The constant characterizing the normal angle (J) distribution of the fragment momentum projection onto the emulsion plane with respect to initial projectile momentum p0 is found to be CJ = (0.37 - 0.02) mrad. Corresponding value C0 = (121 - 6) MeV/c of nucleon momentum distribution in the lead nucleus coincides with that expected from Fermi momentum distribution for this nucleus. The peak in the pair-angle distribution of double-charged fragments, 8Be M 2!, is presented for the region of small angles (<0.1 mrad). The fraction of !-particles coming from the decay of the ground state 8Be is found to be (13 - 2)% of their whole number. 相似文献
54.
The present study demonstrates the development of a supramolecular porous ensemble consisting of hetero‐oligophenylene derivative 6 and Au‐Fe3O4 nanodots. Supramolecular assemblies of AIE‐active hetero‐oligophenylene derivative 6 served as reactors for the generation of Au‐Fe3O4 nanodots. The as prepared supramolecular ensemble functioned as an efficient recyclable photocatalytic system for C(sp2)?H bond activation of anilines for the construction of quinoline carboxylates. Interestingly, the “dip catalyst” prepared by depositing PTh‐co‐PANI‐6: Au‐Fe3O4 nanodots on a filter paper served as a recyclable strip (up to 10 cycles) for C?C/C?N bond formation reaction. 相似文献
55.
Sharma S Vandana Ghoshal SK Arora P Dilbaghi N Chaudhury A 《Applied biochemistry and biotechnology》2009,159(2):310-316
In the present frame of work, Macrophomina phaseolina is encapsulated in silica matrices at various concentrations by low temperature sol-gel technique using tetraethylorthosilicate
(TEOS) as precursor. The optical and photophysical properties of these samples have been studied by second harmonics of Nd:YAG
laser at 532 nm. UV-visible absorption spectra of samples have been recorded and it is found that the absorption increases
with increase in concentration of fungus. Further, a decrease in output transmission intensity of the laser has been observed
with increase in fungus concentration. The temporal response of these samples has also been examined. The results show that
the fungus concentration can be measured within ∼15–20 min. This method of optical sensing of fungus in test sample is faster
than other techniques, such as the conventional colorimetric method which takes about 1 h. 相似文献
56.
Three new ditopic receptors 3a-c based on thiacalix[4]arene of 1,3 alternate conformation possessing two different complexation sites have been designed and synthesized for both soft and hard metal ions. The imino nitrogens bind soft metal ion (Ag+/Pb2+/Cu2+) and the crown moiety binds K+ ion. The preliminary investigations show that 3a-c behave as ditopic receptors for Ag+/K+, Pb2+/K+, and Cu2+/K+ ions, respectively. In all the three receptors it was observed that the formation of 3a·Ag+/3b·Pb2+/3c·Cu2+ complex triggers the decomplexation of K+ ion from crown moiety and acts as a gateway, which regulates the binding of alkali metal to crown moiety. Thus, allosteric binding between metal ions ‘switch off’ the recognition ability of crown ether ring. 相似文献
57.
A simple, isocratic, stability-indicating liquid chromatographic method for quantitative determination of curcumin was successfully developed. The chromatographic separations were achieved using a Hi-Q-Sil C18; 4.6 mm × 250 mm and 10 μm particle size column employing acetonitrile and acetate buffer (pH 3.0; 60: 40, v/v) as the mobile phase. The analyte was subjected to acidic, basic, oxidative, thermal and photo degradation. The method was validated with respect to linearity, precision, accuracy, limit of detection and limit of quantification. Curcumin was detected by UV-Vis detector at 425 nm whereas the degradation products were detected at 280 nm. The method was linear over the concentration range of 1–10 μg mL?1. The limit of detection was found to be 0.06 μg mL?1 and the quantification limit was 0.21 μg mL?1. Considerable degradation of the analyte was observed when it was subjected to alkaline conditions. Accuracy, evaluated as recovery, was in the range of 97–103%. Intra-day precision and intermediate precision showed relative standard deviations <1% and <2% respectively. 相似文献
58.
A proficient etiquette for the stereoselective synthesis of novel 3-methylthio-β-lactams and their Lewis acid mediated functionalization is described. Treatment of 2-methylthioethanoic acid and appropriate imines in the Staudinger reaction leads to the stereocontrolled synthesis of novel trans-3-methylthio-β-lactams in excellent yields. cis-3-Chloro-3-methylthio-β-lactams, obtained from stereoselective chlorination of trans-3-methylthio-β-lactams using N-chlorosuccinimide (NCS) and AIBN, were subjected to Lewis acid (TiCl4 or SnCl4) mediated functionalization using various active aromatic, heterocyclic and aliphatic compounds (nucleophiles). This reaction provides an easy access to novel, stereoselective cis-3-monosubstituted-3-methylthio-β-lactams, which further undergo smooth desulfurization with Raney-nickel to afford C-3 cis- and trans-monosubstituted-β-lactams. The cis or trans configuration of the hydrogen/chloro/nucleophile substituent at C-3 was assigned with respect to C4–H. 相似文献
59.
A pentaquinone based compound 3a has been synthesized which exhibits pronounced fluorescence enhancement in the presence of Zn(2+) ions under a F(-) triggered synergistic effect. Derivative 3a also behaves as a molecular keypad lock with sequential chemical inputs of Zn(2+) and F(-) ions. 相似文献
60.
The binding behavior of triphenylene based copper ensemble prepared in situ has been investigated toward various anions (F(-), Cl(-), Br(-), I(-), CH(3)COO(-), H(2)PO(4)(-), NO(3)(-), OH(-), ClO(4)(-), CN(-), CO(3)(-) and SO(4)(-)) by UV-vis and fluorescence spectroscopy. Among various anions tested, 1-Cu(2+) ensemble shows selective and sensitive response towards cyanide ions and responds to CN(-) ions even in the presence of bovine serum albumin and in blood serum milieu. Further, as practical application of compound 1, we utilized the TLC strips coated with THF solution of 1 for the solid state detection of copper and cyanide ions. 相似文献