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1.
In the present paper, we solve three boundary value problems related to the temperature field in oil strata — the fractional
extensions of the incomplete lumped formulation and lumped formulation in the linear case and the fractional generalization
of the incomplete lumped formulation in the radial case. By using the Caputo differintegral operator and the Laplace transform,
the solutions are obtained in integral forms where the integrand is expressed in terms of the convolution of some auxiliary
functions of Wright function type. A generalization of the Laplace transform convolution theorem, known as Efros’ theorem
is widely used. 相似文献
2.
Density functional calculations have been carried out on a series of linearly annelated acenes and their BN analogues. Even though borazine shows aromatic and reactivity behavior parallel with that of benzene, its condensed derivatives show patterns different from those of their hydrocarbon analogues. Nucleus independent chemical shift (NICS) values in acenes suggest that the aromaticity of the inner rings is more than that of benzene, whereas in BN-acenes there is no substantial change in the aromaticity of the individual rings. Molecular electrostatic potential (MESP) is employed to obtain further insights into the bonding and reactivity trends for these systems. The MESP topography patterns of acenes and BN-acenes are substantially different, with BN-acenes showing more localized pi electron features compared to those of acenes. The MESP values at the critical points (CPs) indicate overall lowering of aromaticity in these annelated systems. However, this change is gradual among the BN-acenes. 相似文献
3.
Structure‐cytotoxicity relationship of di?/tri‐organotin(IV) derivatives of mandelic acid ( 1 – 4 ), L‐proline ( 5 – 7, 15, 16 ), and mixed ligand complexes of latter with 1,10‐phenanthroline ( 8 – 14 ) investigated on the basis of MTT assay against human cancer cell lines, viz. MCF‐7 (mammary cancer), HepG2 (liver cancer) and PC‐3 (prostate cancer) in vitro indicated that all complexes except methyl‐ and octyl‐ analogues displayed potential cytotoxicity. The most active one is dibutyltin(IV) mandelate ( 2 ) exhibiting IC50 2.03 ± 0.40, 0.98 ± 0.23 and 3.86 ± 1.68 μM against MCF‐7, HepG2 and PC‐3, respectively, which is ≈ 15 and 2.5 times against MCF‐7, 20 and 5 times against HepG2 and 5 and ≈ 3 times against PC‐3 more cytotoxic than cis‐platin and 5‐fluorouracil, respectively. Diorganotin(IV) derivatives of mandelic acid are more cytotoxic than triorganotin analogues. Organotin(IV) derivatives of L‐proline (except Bu3Sn(Pro) 16 ) are less cytotoxic than those of mandelic acid but their cytotoxicity is enhanced by complexion with 1,10‐phenanthroline. This may be due to the structural planarity and extended π system of 1,10‐phenanthroline which facilitates their transportation across the cell membrane and enhances the possibility of DNA intercalation over the planar L‐proline ring, and eventually, their DNA binding affinity so as to interfere with the cellular functions of DNA leading to apoptosis. Various biophysical experiments such as DNA fragmentation, acridine orange and comet assays, and flow cytometry assay using annexin V–fluorescein isothiocyanate (FITC) and propidium iodide (PI) have been carried out in order to ascertain their mode of action. The observed results indicated that the major cause of cancer cell death is apoptosis, but a minor role played by necrosis cannot be excluded. It is concluded on the basis of the observed results that the nature and number of organic groups bonded to tin as well as the nature of counter anions play an important role in determining the cytotoxicity of organotin(IV) compounds. 相似文献
4.
Carsten Lenczyk Dr. Dipak Kumar Roy Bijoy Ghosh Johannes Schwarzmann Prof. Ashwini K. Phukan Prof. Dr. Holger Braunschweig 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(36):8585-8589
A series of bis(σ)-borane complexes of Group 6 transition metals were prepared by direct dihydroborane coordination to the metal center. Reaction of [M(CO)3(PCy3)2] and two dihydroboranes [DurBH2] and [(Me3Si)2NBH2] (Dur=2,3,5,6-Me4C6H) yielded bis(σ)-borane complexes fac-[M(CO)3(PCy3){η2-(H2BR)}] (R=Dur; 1 : M=Cr, 2 : M=W; R=N(SiMe3)2; 3 : M=Cr, 4 : M=W). In the case of molybdenum, we have isolated an arene complex ( 5 ) with [DurBH2] in which the Dur group acts as a η6-bound ligand, and with [(Me3Si)2NBH2] a similar bis(σ)-borane complex was isolated, cis,trans-[Mo(CO)2(PCy3)2{η2-(H2BN(SiMe3)2}] ( 6 ), with a different pattern of auxiliary ligands. The complexes were investigated by multinuclear NMR spectroscopy, mass spectrometry, X-ray diffraction analysis, and computational methods. Quantum theory of atoms in molecules (QTAIM) calculations demonstrated that the borane complexes may be described as pure bis(σ)-borane complexes rather than elongated or stretched examples given that the calculations do not show the presence of a ring-critical point (RCP) at the ring formed by the interactions of the B−H with metal center. 相似文献
5.
6.
An expeditious protocol for amidation arylboronic acid has been developed using TsNBr2 as the nitrogen source in presence of a CuI as catalyst. Various arylboronic acids could be transformed into corresponding N-arylsulfonamide derivatives within a very short time using CuI as catalyst in presence of DBU at room temperature. 相似文献
7.
The present paper describes the modification and solar hydrogen production studies employing a new semiconductor-septum (SC-SEP) photoelectrode ns-TiO2/In2O3 based photoelectrochemical solar cell. The current-voltage characteristics of the above SC-SEP cell revealed that an enhancement in short-circuit current (ISC) up to three times (5 ~ 14.6 mA cm?2). The optimum hydrogen production rate was found to be 11.8 lh?1 m?2 for 5M H2SO4 and with a further increase in H2SO4 concentration, the hydrogen production rate was found to be invariant. In yet another part of our study instead of using new SC-SEP solar cell design, we used another new oxide material form such as ns-TiO2/WO3. The ns-TiO2/WO3 exhibited a high photocurrent and photo-voltage of 15.6 mA cm?2, 960 mV, respectively. The ns-TiO2/WO3 electrode exhibited a higher hydrogen gas evolution rate of 13.8 lh?1 m?2. Evidences and arguments are put forward to show that, whereas for the bare ns-TiO2 electrode, the improvement in the performance of this photo-electrode compared with its original form was due to the higher quantum yield. In the case of ns-TiO2/In2O3 and ns-TiO2/WO3 photo-electrodes, the improvement is due to the improved spectral response resulting from decrease of energy band gap. 相似文献
8.
A new hybrid catalyst has been developed by incorporating nicotinic acid onto an organomodified silica. The catalyst was applied as a heterogeneous catalyst for the synthesis of benzoyl fumarate. The reactions work well in the presence of 20 wt % of the catalyst at room temperature to produce the desired products in high yield. The catalyst could be recovered and reused without appreciable change in activity. 相似文献
9.
A fast, simple, and efficient protocol for the direct conversion of alcohols and aldehydes to methyl ester has been developed using TsNBr2 without any catalyst. The one pot reaction proceeds in the presence of a base at room temperature in methanol, to produce the corresponding methyl ester in high yield within a short time. 相似文献
10.
Kakali De Asoke Behera Indranil Banerjee Bharat Sarkar Santanu Ganguly Mridula Misra 《Journal of Radioanalytical and Nuclear Chemistry》2014,301(3):847-861
The aim of this study was to synthesis, a radiolabeled (99mTc) new somatostatin-analogue 6-hydrazinopyridine-3-carboxylic-acid (HYNIC)-Asn3-octreotate (99mTc-HYNIC-AATE), and to evaluate as a candidate for imaging somatostatin-receptor (SSTR)-positive tumors and also compare it with 99mTc-HYNIC-Tyr3-octreotide (99mTc-HYNIC-TOC). Synthesis was performed by Fmoc-solid-phase strategy and 99mTc labeled by SnCl2. Biodistribution and imaging properties of new radiopeptide were also studied in C6 tumor bearing rat. Radiolabeling was performed at high specific activities and it showed high binding-affinity for SSTR2. In biodistribution, radiopeptides have showed high and receptor-specific uptake in the SSTR2 positive organs, tumor with rapid renal excretion from non-target tissues. These results demonstrated that 99mTc-HYNIC-AATE is a new specific radioligand for scintigraphy of somatostatin-receptor-positive tumors. 相似文献