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241.
Shivani Suri K. K. Bamzai Vishal Singh 《Journal of Thermal Analysis and Calorimetry》2011,105(1):229-238
Non-isothermal kinetic parameter of pure and cadmium-doped barium phosphate single crystal grown by room temperature solution
technique have been investigated. Single crystal X-ray diffraction establishes grown crystal to be orthorhombic in nature.
Scanning electron microscopy supplemented with energy dispersive X-ray analysis was used to study the surface features and
to find the exact stoichiometric composition of the grown crystal. Fourier transform infrared spectroscopy studies confirm
the presence of various functional groups. The effect of cadmium doping on pure barium phosphate single crystal was studied
using thermogravimetry analysis. Thermogravimetry studies shows that the pure crystal was stable up to a temperature of 330 °C
whereas doped crystal was stable up to a temperature of 240 °C, i.e., pure crystals were more stable than doped ones. Various
solid-state reaction kinetics, i.e., activation energy (E
a), frequency factor (Z), and entropy (ΔS*) was calculated out to find the mechanism of thermal decomposition at different stages for pure and cadmium doped barium
phosphate. 相似文献
242.
Dong CK Urgaonkar S Cortese JF Gamo FJ Garcia-Bustos JF Lafuente MJ Patel V Ross L Coleman BI Derbyshire ER Clish CB Serrano AE Cromwell M Barker RH Dvorin JD Duraisingh MT Wirth DF Clardy J Mazitschek R 《Chemistry & biology》2011,18(12):1602-1610
Here we report the discovery of tetracyclic benzothiazepines (BTZs) as highly potent and selective antimalarials along with the identification of the Plasmodium falciparum cytochrome bc1 complex as the primary functional target of this novel compound class. Investigation of the structure activity relationship within this previously unexplored chemical scaffold has yielded inhibitors with low nanomolar activity. A combined approach employing genetically modified parasites, biochemical profiling, and resistance selection validated inhibition of cytochrome bc1 activity, an essential component of the parasite respiratory chain and target of the widely used antimalarial drug atovaquone, as the mode of action of this novel compound class. Resistance to atovaquone is eroding the efficacy of this widely used antimalarial drug. Intriguingly, BTZ-based inhibitors retain activity against atovaquone resistant parasites, suggesting this chemical class may provide an alternative to atovaquone in combination therapy. 相似文献
243.
S. Chinnaesakki Manish Chopra Sanjeev Kumar Vishal Arora S. J. Sartandel S. V. Bara R. M. Tripathi V. D. Puranik B. S. Bajwa 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(3):885-892
This study presents the high purity germanium (HPGe) gamma spectrometric measurement of natural radioactivity mainly due to
226Ra, 232Th and 40K in soil samples collected in Ferozepur and Faridkot district of Punjab, India. 226Ra activity varied from 28.6 to 51.1 Bq kg−1 with the mean of 39.7 Bq kg−1. The range and mean activity of 232Th were 42.9–73.2 and 58.2 Bq kg−1, respectively. 40K activity was in the range of 470.9–754.9 Bq kg−1 with the mean of 595.2 Bq kg−1. The air kerma rate (AKR) at 1 m height from the ground was also measured using gamma survey meter in all the sampling locations,
which was ranging from 92.1 to 122.8 nGy h−1 with the mean of 110.6 nGy h−1. The radiological parameters such as Raeq and activity index of the soil samples were also evaluated, which are the tools to assess the external radiation hazard due
to building materials. The mean and range of the Raeq values were 168.7 and 132.9–210.4 Bq kg−1, respectively, whereas the activity index varied from 0.5 to 0.8 with the mean value of 0.62. These indices show that the
indoor external dose due to natural radioactivity in the soil used for the construction will not exceed the dose criteria.
The AKR was also evaluated from soil activity concentration and altitude correction of cosmic radiation contribution. The
statistical tests such as Pearson correlation, spearman rank correlation, box and whisker plot, the Wilcoxon/Mann–Whitney
test and chi-square test, were used to compare the measured AKR with evaluated AKR, which indicates good correlation. 相似文献
244.
Sharma U Verma PK Kumar N Kumar V Bala M Singh B 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(21):5903-5907
Iron phthalocyanine with iron sulfate has been successfully applied for high chemo- and regioselective reduction of aromatic nitro compounds to give the corresponding amines in a green solvent system without using any toxic ligand. The catalytic systems were also compatible with a large range of other reducible functional groups, such as keto, acid, amide, ester, halogen, lactone, nitrile, N-benzyl, O-benzyl, hydroxy, and heterocycles. In the present study, dinitro compounds have been regioselectively reduced to the corresponding amines with high yield. In most of the cases the conversion and selectivity was greater than 99% as determined by GC-MS analysis. 相似文献
245.
A synthesis of sulfoximine-substituted medium-ring nitrogen heterocycles (MRNHs) having a high degree of substitution has been developed. Its key steps are the modular asymmetric synthesis of sulfoximine-substituted N-tethered trienes and their Ru-catalyzed ring-closing metathesis (RCM) reaction. The highly substituted N-tethered trienes were obtained enantio- and diastereopure through 1) the diastereoselective aminoalkylation of sulfoximine-substituted allyltitanium complexes with N-tert-butylsulfonyliminoester, 2) N-allylation of homoallylic N-sulfonyl amines, 3) allylation, hydroxylalkylation, and formylation of α-lithioalkenylsulfoximines, and 4) allylation of α-formylalkenylsulfoximines. The Ru-catalyzed RCM reaction of the sulfoximine-substituted 1,7,10- and 1,7,12-trienes stereoselectively afforded the corresponding nine-, ten-, and eleven-membered MRNHs in good yields. An interesting difference in reactivity was noted in the case of a sulfoximine-substituted 1,7,10-triene and its corresponding 1,10-diene. While the triene readily underwent a RCM reaction, the diene reacted only in the presence of Ti(OiPr)(4) under formation of the corresponding MRNH. The feasibility of a removal of the sulfoximine auxiliary and the N-sulfonyl protecting group from the MRNHs were demonstrated through reduction and cleavage, respectively, of a nine-membered heterocycle, both of which proceeded readily and gave the corresponding cyclic alkene and amine, respectively. 相似文献
246.
Nicholas Leventis Sudhir Mulik Xiaojiang Wang Amala Dass Vishal U. Patil C. Sotiriou-Leventis Hongbing Lu Gitogo Churu Alex Capecelatro 《Journal of Non》2008,354(2-9):632-644
Macroporous (1–5 μm) monolithic silica aerogels consisting of both random but also ordered mesoporous walls have been synthesized via an acid-catalyzed sol–gel process from tetramethoxysilane (TMOS) using a triblock co-polymer (Pluronic P123) as a structure-directing agent and 1,3,5-trimethylbenzene (TMB) as a micelle-swelling reagent. Pluronic P123 was removed by Soxhlet extraction, and materials in monolithic form were obtained by extracting the pore filling solvent with liquid CO2, which eventually was taken out supercritically. Although these monoliths are more robust than base-catalyzed silica aerogels of similar density, nevertheless, the mechanical properties can be improved dramatically by letting an aliphatic di-isocyanate (Desmodur N3200) react with the silanols on the macro- and mesoporous surfaces. As it turns out, the polymer fills the mesopores and coats conformally the macropores of templated samples, so that BET surface areas decrease dramatically, from 550–620 m2 g?1 to <5 m2 g?1. By comparison, polymer nano-encapsulation of non-templated acid-catalyzed aerogels preserves a large fraction of their mesoporous surface area, and BET values decrease from 714 m2 g?1 to 109 m2 g?1. Finally, since polymer nano-encapsulation preserves the macroscopic physical dimensions of the monoliths before drying, comparative analysis of the physical dimensions against XRD data of native versus polymer nano-encapsulated samples provides evidence that upon drying macropores (micron size regime) shrink less than mesopores (nanometer size regime). 相似文献
247.
Archana Gupta Vishal Sharma Pawan Kumar Mishra Adam Ekielski 《Molecules (Basel, Switzerland)》2022,27(24)
Water gets polluted due to the dumping of untreated industrial waste into bodies of water, particularly those containing heavy metals and dyes. Industrial water contains both inorganic and organic wastes. Numerous adsorbents that are inexpensive and easily available can be used to address the issue of water deterioration. This review report is focused on polyacrylonitrile as an efficient constituent of adsorbents to extract toxic ions and dyes. It discusses the various formulations of polyacrylonitrile, such as ion exchange resins, chelating resins, fibers, membranes, and hydrogels, synthesized through different polymerization methods, such as suspension polymerization, electrospinning, grafting, redox, and emulsion polymerization. Moreover, regeneration of adsorbent and heavy metal ions makes the adsorption process more cost-effective and efficient. The literature reporting successful regeneration of the adsorbent is included. The factors affecting the performance and outcomes of the adsorption process are also discussed. 相似文献
248.
Vishal Budhija Phebe H. van Langevelde Konstantin B. Krause Dr. Beatrice Cula Dr. D. G. H. Hetterscheid Dr. Matthias Schwalbe 《欧洲无机化学杂志》2023,26(14):e202200743
Synthesis, characterization and reactivity studies of a hetero-dicopper complex, particularly towards oxygen reduction are presented. A bischlorido copper(II) trishistidine-type coordination unit is positioned directly above a copper porphyrin unit. The close distance between the two coordination fragments is secured by a rigid xanthene backbone. Surprisingly, the dinuclear complex is not active towards oxygen reduction unlike the earlier published mononuclear analogues with a bispyridylamine copper center. However, the compound architecture of this multinuclear metal complex is interesting and can play an important role in the development of new catalysts for ORR. 相似文献
249.
An operationally simple process has been developed for the synthesis of unsymmetrical amines and α-amino carbonyl derivatives in the absence of a catalyst, ligand, oxidant, or any additives. Contrary to known reductive amination methods, this protocol is amenable to substrates containing other reducible groups. This process effectively results in consecutive cleavage and formation of C−N bonds. DFT studies and Hammett analysis provide useful insight into the mechanism. The role of noncovalent interactions as a stabilizing factor have been examined in the protocol. A wide range of alkyl-bromides have been coupled efficiently with a variety of dimethyl anilines to get unsymmetric tertiary amines with yields up to 90%. This methodology was further extended to the synthesis of α-amino carbonyl derivatives with yields up to 93%. 相似文献
250.