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101.
Natarajan Arumugam Abdulrahman I. Almansour Raju Suresh Kumar Vagolu Siva Krishna Dharmarajan Sriram Ramanathan Padmanaban 《Arabian Journal of Chemistry》2021,14(2):102938
A stereo- and regioselective synthesis of hitherto unexplored novel class of β-lactam embedded spirooxindolopyrrolidine hybrid heterocycles have been accomplished via ionic liquid accelerated [3 + 2]-cycloaddition reaction process. The expected unusual lactonization/lactamization product could not be observed even in traces. The in vitro antimycobacterium tubercular activity of the synthesized spiroheterocyclic hybrids were assessed against Mycobacterium tuberculosis H37Rv. Among them, the compounds with no substitution and chlorosubstitution on the oxindole ring showed the most potent activity with a MIC 0.78 μg/mL and 1.56 μg/mL, respectively which were two-fold and equal activity than the standard drug, ethambutol (MIC = 1.56 μg/mL). 相似文献
102.
Naved Azum Malik Abdul Rub Abdullah M. Asiri Aftab Aslam Parwaz Khan Anish Khan Sher Bahadar Khan Mohammad M. Rahman Abdulrahman O. Al-Youbi 《Journal of solution chemistry》2013,42(7):1532-1544
Pyrene fluorescence measurements were carried out on various binary mixtures of the antidepressant amphiphilic drug amitriptyline hydrochloride (AMT) with conventional (TTAB and CTAB) and gemini surfactants (14-4-14 and 16-4-16). In all cases mixed micellar aggregates were formed and the mixed critical micelle concentration (cmc) of various mixtures was computed from the I 1/I 3 versus total surfactant concentration plots. In the region where mixed micelles are formed, the interaction of the amphiphlic drug and four surfactants showed synergistic behavior. The results were analyzed using an interaction parameter, β, which characterize the interaction in the mixed micelle and is introduced by a regular solution theory. The β values are negative in all binary mixtures, and their magnitudes increase with increasing hydrophobicity of the amphiphile. The micellar mole fraction of AMT in the mixed micelle (x 1) and in the ideal sate (x ideal) were evaluated and their values (x 1 > x ideal) suggest that the contribution of the AMT component is greater in binary mixtures as compared to that in the ideal state. Activity coefficients (f 1 and f 2) and excess Gibbs energy (G ex) were also calculated. The values of micelle aggregation numbers (N agg) and various other parameters like the Stern–Volmer constant (K sv), micropolarity and dielectric constant of mixed systems have also been evaluated from the ratios of respective peak intensities (I 1/I 3 or I 0/I 1). 相似文献
103.
Abdulrahman Alfuraih Khalid Alzimami Andy K. Ma Ali Alghamdi 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):1025-1029
Zirconium-89 (89Zr) can be produced in a cyclotron by focusing the proton beam on an yttrium-89 (89Y) foil target. Optimal combination of beam energy and target assembly configuration enables maximum production of 89Zr while minimizing the formation of contaminant nuclides such as 88Zr and 88Y to allow efficient and effective radiopharmaceutical labeling. Accurate modeling of the proton beam and the target is therefore an essential step to assure the best beam and target specification. We used the radiation transport code MCNPX to simulate the transport of protons through the irradiation assembly and the nuclear reaction code TALYS to obtain the production cross sections of various nuclides from proton-89Y reactions. Results from simulating the irradiation of 14 mm diameter targets with aluminum (Al) degrader at 19.8 mA for 1 h suggested that the 0.15 mm thick one would produce 227 MBq while the 0.3 mm thick one would produce 413 MBq of 89Zr with less than 1 % uncertainty. These results show excellent agreement with experimental work in literature. This work provides the basis for further experimental and theoretical assessments of the use of 89Zr as radiopharmaceutical labels. 相似文献
104.
Ali Firoozichahak Abdulrahman Bahrami Farshid Ghorbani Shahna Saber Alizadeh Davood Nematollahi Maryam Farhadian 《Journal of separation science》2020,43(5):1011-1018
We developed a novel method of needle trap device packed with titanium‐based metal‐organic framework for the extraction of phenolic derivatives in air followed by gas chromatography‐flame ionization detector analysis. The synthetized adsorbent was packed inside a 22‐gauge spinal needle. This method was first tested at laboratory scale, and then was used for field sampling of phenolic derivatives in air. A glass chamber placed on a heater at 60°C was used to provide different concentrations of phenolic derivatives. The desorption conditions and breakthrough volume were optimized using response surface methodology. The limit of detection and limit of quantitation of the proposed method were estimated to be in the range of 0.001–0.12 and 0.003–0.62 ng/mL, respectively, indicating a high sensitivity for the suggested sampler. Storing the packed needle trap device in a refrigerator at 4?C for 60 days did not dramatically affect the storage stability. Our findings indicated that there was a high correlation coefficient (R2 = 0.99) between the measurement results of this method and the NIOSH recommended method (XAD‐7 sorbent tube). Therefore, it can be concluded that the needle trap device packed with titanium‐based metal‐organic framework can be used as a efficient method for extraction of phenolic derivatives in air. 相似文献
105.
Muhammad Ali Hashmi Umar Farooq Syeda Sidra Bibi Sadia Naz Hong-Guang Xu Basim H. Asghar Yahia Nasser Mabkhot Abdulrahman Alsayari Abdullatif Bin Muhsinah Ayesha Khan 《中国化学会会志》2020,67(4):558-566
A comprehensive theoretical model was designed for two new flavanols that have been reported from Glycosmis pentaphylla, differing in the placement of α-pyrone ring. The density functional theory (DFT) approach was utilized for computing different properties of these compounds to validate the experimental findings and stereochemical assignments. Electronic properties, geometric parameters, frontier molecular orbitals (FMOs), molecular electrostatic potential (MESP), and natural bond orbital analysis were performed for the first time at the PBE0-D3BJ/def2-TZVP level of theory for the compounds under study. The simulated vibrational frequencies for compounds 1 and 2 were computed and compared with the experimental results. nuclear magnetic resonance (NMR) (1H and 13C) chemical shift values were computed at the PBE0-D3BJ/def2-TZVP/SMDDMSO level of theory and showed a very good agreement with the experimental results for both the compounds. The electronic circular dichroism (ECD) and ultraviolet–visible (UV) spectra for both the compounds were obtained using time-dependent DFT in methanol, whose results exhibited excellent correlation with experimental data. The intermolecular interaction effect on geometric parameters, vibrational frequencies, and electronic properties were studied for the first time. 相似文献
106.
Abdulrahman Alsayari Abdullatif Bin Muhsinah Yahya I. Asiri Mohammad Y. Alfaifi Serag Eldin I. Elbehairi Fatima Alatibi Nahed Nasser E. El-Sayed Yahia N. Mabkhot 《Journal of heterocyclic chemistry》2020,57(7):2911-2922
5-(2-Bromoacetyl)-2,3,4-trisubstituted-thiophene was used as a synthetic intermediate to prepare a series of thiophene derivatives and thiophene incorporating oxazole, imidazole, thiazole, pyrrole, and pyridine rings via substitution and cyclo-condensation reactions. The data were extracted from the spectra of the resulting products confirmed their suggested structures. The newly synthesized compounds were screened to evaluate their in vitro antimicrobial activity vs several positive and negative gram bacteria and fungi. The screening data revealed that the thiophene derivative 7a , incorporating a thiazole ring, displayed strong activity against all tested microorganisms when compared with the antibiotics used. 相似文献
107.
Abdulrahman Abdul-Hadi 《Journal of Radioanalytical and Nuclear Chemistry》1998,231(1-2):147-152
The γ-ray spectrum of241Am was reinvestigated by using intense sources. A purified solution source was used to make sure that the γ-lines presents
in the spectrum come from the α-decay of241Am. The γ-spectrometer consists of 40% relative efficiency HPGe detector and 8192-channel ADC. Out of 137 γ-lines that are
presents in the spectrum 46 are new. 相似文献
108.
The acceleration form of constraint equations is utilized in this paper to solve for the inverse dynamics of servo-constraints. A condition for the existence of control forces that enforce servo-constraints is derived. For overactuated dynamical systems, the generalized Moore-Penrose inverse of the constraint matrix is used to parameterize the solutions for these control forces in terms of free parameters that can be chosen to satisfy certain requirements or optimize certain criterions. In particular, these free parameters can be chosen to minimize the Gibbsian (i.e., the acceleration energy of the dynamical system), resulting in ideal control forces (those satisfying the principle of virtual work when the virtual displacements satisfy the servo-constraint equations). To achieve this, the nonminimal nonholonomic form recently derived by the authors in the context of Kanes method is used to determine the accelerations of the system, and hence to determine the forces to be generated by the redundant manipulators. Finally, an extension to inverse dynamics of servo-constraints involving control variables is made. The procedures are illustrated by two examples. 相似文献
109.
Advances in chiral separations of small peptides by capillary electrophoresis and chromatography 下载免费PDF全文
Imran Ali Zeid A. Al‐Othman Abdulrahman Al‐Warthan Leonid Asnin Alexander Chudinov 《Journal of separation science》2014,37(18):2447-2466
Many chemical and biological processes are controlled by the stereochemistry of small polypeptides (di‐, tri‐, tetra‐, penta‐, hexapeptides, etc). The biological importance of peptide stereoisomers is of great value. Therefore, the chiral resolution of peptides is an important issue in biological and medicinal sciences and drug industries. The chiral resolutions of peptide racemates have been discussed with the use of capillary electrophoresis and chromatographic techniques. The various chiral selectors used were polysaccharides, cyclodextrins, Pirkle types, macrocyclic antibiotics, crown ethers, imprinted polymers, etc. The stereochemistry of dipeptides is also discussed. Besides, efforts are made to explain the chiral recognition mechanisms, which will be helpful in understanding existing and developing new stereoselective analyses. Future perspectives of enantiomeric resolution are also predicted. Finally, the review concludes with the demand of enantiomeric resolution of all naturally occurring and synthetic peptides. 相似文献
110.
Ismail Khalil Warad M. Rafiq H. Siddiqui Saud Al-Resayes Abdulrahman Al-Warthan Refaat Mahfouz 《Transition Metal Chemistry》2009,34(3):347-352
Reaction of the ruthenium phosphine complex [RuCl2(PPh3)3] 1 with an unsaturated functionalized diphosphine ligand, namely 1,1-bis(diphenyl-phosphinomethyl)ethene, H2C=C(CH2PPh2)2, (dppme) gave trans-Cl2Ru(dppme)2
2. Complex 2 served as a precursor for the synthesis of trans-Cl2Ru(dppme)(alkylamine)2 complexes 3–5 by reaction with RNH2. All these complexes were characterized by spectroscopic techniques and by elemental analysis. The solid-state structure
of complex 2 was determined by X-ray crystallography. 相似文献