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91.
Asiri Nanayakkara 《Pramana》2003,61(4):739-747
In this paper, we present a semiclassical eigenenergy expansion for the potential |x|α when α is a positive rational number of the form2n/m (n is a positive integer and m is an odd positive integer). Remarkably, this expansion is found to be identical to the WKB expansion
obtained for the potentialx
N(N-even), if2n/m is replaced byN. Taking the limitm → 2 of the above expansion, we obtain an explicit asymptotic energy expansion of symmetric odd power potentials |x|2j+1 (j- positive integer). We then show how to develop approximate semiclassical expansions for potentials |x|α when α is any positive real number. 相似文献
92.
B. Avula L. M. Tripathi S. I. Khan B. L. Tekwani D. Nanayakkara W. Gul M. A. ElSohly I. A. Khan 《Chromatographia》2006,64(7-8):429-434
NPC1161 is an 8-aminoquinoline anti-malarial analog, which has a favorable toxicity profile relative to primaquine and other 8-aminoquinolines. High-performance liquid chromatographic method was developed for the determination of NPC1161, primaquine and their metabolites in biological samples in order to facilitate metabolic and pharmacokinetic studies. The method includes extraction of the unchanged drugs and their metabolites from the biological samples. Separation was achieved by reversed-phase chromatography on a C18 column with water–acetonitrile both containing 0.025% trifluoroacetic acid as the mobile phase. Recoveries of NPC1161 and its metabolites were greater than 60% in various biological samples tested. No interference with the components of the biological material was observed. The detector response was linear with concentrations of NPC1161 and its metabolites (desalkyl NPC1161 and carboxy NPC1161) in the ranges from 0.5 to 80.0, 0.4–60.0 and 0.4–70.0 μg mL−1, respectively. A mass spectrometry coupled with electrospray ionization (ESI) interface method is described for the identification of NPC1161 and its metabolites in biological samples. This method involved the use of the [M + H]+ions of NPC1161, C3 analog (internal std. for the assay), desalkyl NPC1161 and carboxy NPC1161 at m/z 434, 406, 349 and 449 in the positive ion mode with extractive ion monitoring (EIM). This method will have an important application in pharmacokinetic studies of NPC1161 and in understanding the mechanism of metabolism of this novel 8-aminoquinoline analog in more detail. 相似文献
93.
M. A. ElSohly W. Gul S. Feng N. P. D. Nanayakkara A. M. Clark S. Khan F. B. Cogswell L. A. Walker 《Chromatographia》2006,64(3-4):199-205
This study describes a novel and simple GC-MS procedure developed for the determination of the concentration of the 8-aminoquinoline antimalarial agent NPC1161 and its carboxy metabolite in plasma and red blood cells. Preliminary pharmacokinetic data were generated for the two enantiomers of NPC1161 in monkeys. NPC1161, the internal standard, and desalkyl metabolite were converted to their mono-heptafluorobutyrates, while the carboxy metabolite underwent an intramolecular cyclization to give a lactam product. The calibration curves were linear ranging from 10 to 2,000 ng mL−1. The developed GC-MS method is sensitive and reproducible for measuring blood level of this antimalarial drug. 相似文献
94.
Solution properties of phenothiazine drug promazine hydrochloride with cationic hydrotropes in aqueous/electrolyte solution at different temperature 下载免费PDF全文
Malik Abdul Rub Naved Azum Abdullah M. Asiri Mohie E. M. Zayed Abdulrahman O. Al‐Youbi 《Journal of Physical Organic Chemistry》2016,29(9):476-489
The current work deals with the mixed micellization phenomena of surface active promazine hydrochloride (PMZ) drug with cationic hydrotropes (para‐toluidine hydrochloride and ortho‐toluidine hydrochloride) in absence and occurrence of 50 mmol kg?1 NaCl at five different temperature (293.15–313.15 K). PMZ is an amphiphilic phenothiazine drug and employed for the cure of mania and schizophrenia. Conductometry measurement was employed to gain a detailed picture of the interactions between drug and hydrotrope molecules. The experimental data were analyzed according to different mixing models within the outline of the pseudophase separation model. The evaluated values of critical micelle concentration (cmc) were found to be inferior than cmcid values signifying attractive interactions involving the both components in the solutions. NaCl further reduces the cmc of pure amphiphiles and their mixed systems as a result of screening of the electrostatic repulsion between the polar head groups. The micellar mole fractions (X1) of hydrotropes evaluated by various proposed models were constantly more than ideal values ( ) signifying high involvements of hydrotrope in mixed micelles. Activity coefficients ( and ) were always below one in all cases signifying synergism in mixed micelles. Thermodynamic parameters favor the process of micellization which is found to be entropy driven. The negative values of free energies of mixing demonstrated the stability of the mixed systems of drug and hydrotrope. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
95.
Herme G. Baldoví Marcos Latorre-Sánchez Iván Esteve-Adell Anish Khan Abdullah M. Asiri Samia A. Kosa Hermenegildo Garcia 《Journal of nanoparticle research》2016,18(8):240
MoS2 quantum dots (QDs) have been obtained in colloidal suspensions by 532 nm laser ablation (7 ns fwhp/pulse, 50 mJ/pulse) of commercial MoS2 particles in acetonitrile. High-resolution transmission electron microscopy images show a lateral size distribution from 5 to 20 nm, but a more homogeneous particle size of 20 nm can be obtained by silica gel chromatography purification in acetonitrile. MoS2 QDs obtained by laser ablation are constituted by 3–6 MoS2 layers (1.8–4 nm thickness) and exhibit photoluminescence whose λPL varies from 430 to 530 nm depending on the excitation wavelength. As predicted by theory, the confinement effect and the larger periphery in MoS2 QDs increasing the bandgap and having catalytically active edges are reflected in an enhancement of the photocatalytic activity for H2 generation upon UV–Vis irradiation using CH3OH as sacrificial electron donor due to the increase in the reduction potential of conduction band electrons and the electron transfer kinetics. 相似文献
96.
Inside Back Cover: Initial Carbon–Carbon Bond Formation during the Early Stages of the Methanol‐to‐Olefin Process Proven by Zeolite‐Trapped Acetate and Methyl Acetate (Angew. Chem. Int. Ed. 51/2016) 下载免费PDF全文
Dr. Abhishek Dutta Chowdhury Dr. Klaartje Houben Dr. Gareth T. Whiting Prof. Dr. Mohamed Mokhtar Prof. Dr. Abdullah M. Asiri Prof. Dr. Shaeel A. Al‐Thabaiti Prof. Dr. Suliman N. Basahel Prof. Dr. Marc Baldus Prof. Dr. Bert M. Weckhuysen 《Angewandte Chemie (International ed. in English)》2016,55(51):15929-15929
97.
Metal–Organic Framework (MOF) Compounds: Photocatalysts for Redox Reactions and Solar Fuel Production 下载免费PDF全文
Prof. Dr. Amarajothi Dhakshinamoorthy Prof. Dr. Abdullah M. Asiri Prof. Dr. Hermenegildo García 《Angewandte Chemie (International ed. in English)》2016,55(18):5414-5445
Metal–organic frameworks (MOFs) are crystalline porous materials formed from bi‐ or multipodal organic linkers and transition‐metal nodes. Some MOFs have high structural stability, combined with large flexibility in design and post‐synthetic modification. MOFs can be photoresponsive through light absorption by the organic linker or the metal oxide nodes. Photoexcitation of the light absorbing units in MOFs often generates a ligand‐to‐metal charge‐separation state that can result in photocatalytic activity. In this Review we discuss the advantages and uniqueness that MOFs offer in photocatalysis. We present the best practices to determine photocatalytic activity in MOFs and for the deposition of co‐catalysts. In particular we give examples showing the photocatalytic activity of MOFs in H2 evolution, CO2 reduction, photooxygenation, and photoreduction. 相似文献
98.
Presence versus Proximity: The Role of Pendant Amines in the Catalytic Hydrolysis of a Nerve Agent Simulant 下载免费PDF全文
Dr. Timur Islamoglu Dr. Manuel A. Ortuño Emmanuel Proussaloglou Dr. Ashlee J. Howarth Dr. Nicolaas A. Vermeulen Ahmet Atilgan Prof. Abdullah M. Asiri Prof. Christopher J. Cramer Prof. Omar K. Farha 《Angewandte Chemie (International ed. in English)》2018,57(7):1949-1953
Amino‐functionalized zirconium‐based metal‐organic frameworks (MOFs) have shown unprecedented catalytic activity compared to non‐functionalized analogues for hydrolysis of organophosphonate‐based toxic chemicals. Importantly, the effect of the amino group on the catalytic activity is significantly higher in the case of UiO‐66‐NH2, where the amino groups reside near the node, compared to UiO‐67‐m‐NH2, where they are directed away from the node. Herein, we show that the proximity of the amino group is crucial for fast catalytic activity towards hydrolysis of organophosphonate‐based nerve agents. The generality of the observed amine‐proximity‐dictated catalytic activity has been tested on two different MOF systems which have different topology. DFT calculations reveal that amino groups on all the MOFs studied are not acting as Brønsted bases; instead they control the microsolvation environment at the Zr6‐node active site and therefore increase the overall catalytic rates. 相似文献
99.
M. Sc. Vanessa Claus Michael Schukin Siegfried Harrer Dr. Matthias Rudolph Prof. Dr. Abdullah M. Asiri Dr. Jin Xie Prof. Dr. A. Stephen K. Hashmi 《Angewandte Chemie (International ed. in English)》2018,57(39):12966-12970
We have developed a simple gold‐catalyzed procedure for the synthesis of substituted and modifiable azulenes. The azulenes are formed either by the dimerization of push–pull diarylalkynes bearing a fluorine atom in ortho or para position or by the dimerization of a symmetric electron‐rich diarylalkyne. In the presence of a cationic gold catalyst, the two alkynes can form a highly reactive vinyl cation. Trapping of this high‐energy intermediate by an appropriate aryl unit then delivers substituted azulenes in a single step and in a perfect atom economy. 相似文献
100.
Chitosan‐Templated Synthesis of Few‐Layers Boron Nitride and its Unforeseen Activity as a Fenton Catalyst 下载免费PDF全文
Dr. Ana Primo Dr. Sergio Navalón Dr. Abdullah M. Asiri Prof. Hermenegildo García 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):324-330
A novel procedure for the preparation of few‐layers boron nitride (BN), either as films or as suspended BN platelets, is presented, based on the pyrolysis of chitosan, which serves both as a matrix to embed ammonium borate and as a template for BN synthesis. The resulting BN samples are characterized by XRD, Raman and X‐ray photoelectron spectroscopy, and by TEM and AFM imaging. The samples exhibit deep UV emission, which is characteristic of high quality BN. This template synthesis and the easy exfoliation of BN platelets facilitate the use of BN as an extremely high‐efficiency Fenton catalyst for the generation of highly aggressive hydroxyl radicals in water. 相似文献