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61.
In recent years, angular and linear phenoxazines and their derivatives and polymers have attracted much attention due to their great pharmacological and industrial utility. So it becomes imperative to review the work done in this area more frequently. Therefore, various synthetic routes for phenoxazines are reviewed here comprehensively. 相似文献
62.
Summary Different fluxes and spectra of galactic cosmic rays (GCR) and solar cosmic rays result in a wide variety of radioactive and
stable-nuclides production rates. The records of cosmic-ray interactions, have been studied in terrestrial archives, in meteorites,
cosmic dust and lunar samples. We present here some results obtained in our laboratory on the study of cosmogenic radionuclides
produced in meteorites which fell in the last century. The laboratory is situated in the underground station of Monte dei
Cappuccini, Torino, at a depth of 70 m water equivalent to reduce the cosmic-ray background level. To measure γ-activity in
meteorites we have set up a highly efficient and selective Ge−NaI(Tl) γ-ray spectrometer surrounded by a passive shield. The
solar modulation affects the intensity of GCR and therefore the isotopes production rates in meteorites. The 11 y solar cycle
is well reproduced by the variations of22Na (T
1/2=2.6 y) in meteorites which fell during the past three solar cycles. The44Ti (T
1/2=66.6 y) activity measured in eight chondrites which fell in the last 110 y is qualitatively consistent with the century-scale
solar-activity variation, called the Gleissberg cycle. The increase is roughly four times higher, than expected (about 5%)
for a GCR flux calculated by a model in which the solar-activity modulation is determined solely by the sunspot number indexR. This result suggests a much weakened modulation of GCR during the prolonged Gleissberg minimum during which highly ordered
magnetic fields set up in the heliosphere. 相似文献
63.
64.
65.
Shruti S. Devangamath 《International Journal of Polymer Analysis and Characterization》2018,23(6):517-528
Organic–inorganic polymer hybrid films of epoxy polymer were prepared, using Cobaltous sulfate heptahydrate (CoSO4.7H2O) as a filler component, by physical blending method. UV–Vis optical absorption spectra were analyzed to determine optical band gaps (Eg) of the hybrid material. FTIR studies revealed the interaction of inorganic component with molecules of the polymer matrix. Glass transition temperature (Tg) and degradation temperature were determined by DSC. TG analysis showed the improvement in thermal stability of prepared hybrid films. XRD patterns revealed the amorphous nature of the pure epoxy polymer. Additional sharp peaks were seen for higher filler levels (FLs), indicating self formed nanostructures in the material, which was also evident from SEM analysis. 相似文献
66.
Azithromycin is a broad spectrum antimicrobial agent that is approved in the United States for use in humans. Due to azithromycin's low rate of metabolism it is likely to be found in wastewater treatment plants, where its broad spectrum of antimicrobial activity could lead to development of resistance in bacteria. A liquid-liquid extraction using K2CO3 and methyl-t-butyl ether (MTBE) was used to extract azithromycin from 10 ml aliquots of wastewater. Liquid chromatography was performed using a Luna C18(2) (30 mm x 2.0 mm) column with a mass spectrometer friendly mobile phase containing 50:24:2:24 acetonitrile, methanol, tetrahydrofuran, and 0.04 M ammonium hydroxide. The mass spectrometer used an electrospray source with positive ionization and an ion trap detector. A linear standard curve from 5 to 200pg/ml was validated and used to quantitate azithromycin in wastewater. 相似文献
67.
J. Uttamchandani S. K. Mehrotra A. M. Bhandari Prof. R. N. Kapoor 《Monatshefte für Chemie / Chemical Monthly》1977,108(3):735-741
Reactions of Aluminium isopropoxide with monofunctional bidentateSchiff bases, such as salicylidene-o-toluidine, salicylidene-p-toluidine, 2-hydroxy-1-naphthylmethylidene-p-toluidine and 2-hydroxy-1-naphthylmethylidene-p-toluidine in different stoichiometric ratios have yielded products of the type Al(OPr
i)2(SB), Al(OPr
i)(SB)2, and Al(SB)3 (whereSB
– is the anion of the correspondingSchiff base,SBH). Bifunctional tetradentateSchiff bases in 11 and 23 molar ratios [Al(OPr
i)3:SBH2] yielded insoluble derivatives of the type Al(OPr
i)SB and Al2(SB)3 (whereSB
– represents the anion of theSchiff baseSBH2 andSBH2=bis-salicylaldehyde-o-phenylene-diamine or bis-salicylaldehyde-p-phenylenediamine). The newSchiff base derivatives have been characterized by elemental analyses, infrared spectroscopy and molecular weight determinations. 相似文献
68.
69.
Pallab Bhandari Prof. Partha Sarathi Mukherjee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(57):e202201901
Synthesis of robust covalent macrocycles/cages via multiple amide-bond forming reaction is highly challenging and generally it needs multistep reactions. One-pot reaction of appropriate di-/tri-acyl chloride with a diamine generally results polymers or oligomers instead of discrete architectures. To overcome this limitation, a strategy is reported here using dynamic imine chemistry for facile construction of imine-based macrocycle and cage upon treatment of a diamine with di- and tri-aldehydes respectively, followed by post-synthesis one-step conversion of imine bonds to amides to form the desired robust macrocycle and cage containing multiple amide bonds. While the macrocycle was found to form aggregates in DMSO, the cage was intact without any aggregation. Six amide groups in the confined pocket of the cage made it an ideal receptor for selective binding of fluoride with very high selectivity (∼3 103 fold) over chloride, and it was silent towards other halides, phosphate, and other oxyanions. 相似文献
70.
Jyoti Singh Nicole Steck Debaditya De Alexandre Hofer Alexander Ripp Ilya Captain Manfred Keller Paul A. Wender Rashna Bhandari Henning J. Jessen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):3968-3973
An iterative polyphosphorylation approach is described, which is based on a phosphoramidite (P‐amidite) derived reagent (c‐PyPA) obtained from the cyclization of pyrophosphate with a reactive diisopropylaminodichlorophosphine. This type of reagent is unprecedented as it represents a reactive P‐amidite without protecting groups. The reagent proved to be stable in solution over several weeks. Its utility is described in the context of iterative monodirectional and bidirectional polyphosphorylations. The ensuing functionalized cyclotriphosphate can be opened with a variety of nucleophiles providing ready access to diverse functionalized polyphosphate chains of defined length with several tags, including both P‐N and P‐O labels. Their interaction with exo‐ and endopolyphosphatases is described. 相似文献