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261.
Muhammad Akhyar Farrukh Fizza Naseem Ayesha Imtiaz Muhammad Khaleeq-ur-Rahman Tatiana Duque Martins Khalid Mahmood Zia 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(6):1231-1237
Surfactant-assisted synthesis of leucite (KAlSi2O6) nanoparticles was carried out by a hydrothermal method using an anionic surfactant at variable temperatures and surfactant concentrations. The newly synthesized leucite nanoparticles were characterized by FTIR, TGA, XRD, FESEM, and TEM. These nanoparticles have a wide and direct band gap at their smallest particle size (Eg = 3.30 eV), showing a significant quantum confinement effect. Samples of leucite were prepared at 180°C with different SDS concentrations 0.006, 0.007, 0.008, 0.009, and 0.01 M and were used to degrade methylene blue under ultraviolet radiations. These samples degraded methylene blue to 18.5, 31.7, 45.81, 31.61, 30.1%, respectively. The most effective catalyst is the one which was synthesized at 200°C and the CMC value of the surfactant (sodium dodecyl sulfate) having the percentage degradation of 49.1%. 相似文献
262.
263.
The effect of different mineral acids on the absorption signals of lead and cadmium in atomic absorption spectrometry is reported. The behaviour of the signals was studied with respect to variations in metal concentration, acid concentration, flame stoichiometry and burner height. For the determination of lead and cadmium the most suitable concentrations of hydrochloric, nitric, sulphuric and perchloric acids were 5, 5, 2.5 and 5%, respectively. Similar absorption behaviour was observed in oxidizing and reducing flames for lead and cadmium in all the acids studied. 相似文献
264.
Ajaz Ahmad Sujan Kumar Mondal Basit Latief Jan Debabrata Mukhopadhyay Rajkumar Banerjee Khalid M. Alkharfy 《Biomedical chromatography : BMC》2016,30(12):2024-2030
A lipid‐conjugated, estrogenic derivative molecule, ESC8, compared with other estrogenic molecules, encourages cell death in both ER‐positive and ER‐negative breast cancer cells. A rapid and highly sensitive assay method has been developed and validated for the estimation of a ESC8 in rat plasma using liquid chromatography coupled with mass spectrometry under positive‐ion mode with electrospray ionization. The sample process includes using methanol for precipitation of ESC8 and dextromethorphan (internal standard, IS) from plasma. Chromatographic separation was achieved with methanol–water–formic acid (70:30:0.1% v/v/v) pumped at a flow rate of 0.3mL/min and a C18 column (50 × 2.1 mm i.d., 1.7 μm particle size) with a total run time of 5 min. The m/z ions monitored were 568.5 and 272.1 for ESC8 and IS, respectively. The lower limit of quantitation achieved was 1.08 ng/mL and linearity was observed from 5 to 500 ng/mL. The intra‐ and inter‐day precisions were <4%. The proposed method was successfully applied to a preliminary pharmacokinetic study of ESC8 liposomal formulation following an intraperitoneal administration of 3.67 mg/kg in rats. The concentrations of ESC8 in plasma were quantifiable up to 36 h. The peak concentration of ESC8 was found to be 110.72 ng/mL, the area under the concentration–time curve was 1625.23ng/mL h and the half‐life was 11.72 h. 相似文献
265.
A Facile One‐Pot Synthesis and Anticancer Evaluation of Novel Substituted 1,2‐Dihydropyridine and 1,2,3,4‐Tetrahydropyrimidine Analogues 下载免费PDF全文
Ahmed Bari Mohammad Khalid Parvez Azmat Ali Khan Amer M. Alanazi Saeed Ali Syed Mohammed S. Al‐Dosari Abdulrahman M. Alobaid 《Journal of heterocyclic chemistry》2016,53(2):377-382
Current paper involves the one‐pot synthesis of various 1,2‐dihydropyridine and 1,2,3,4‐tetrahydropyrimidine analogues. The antitumor activity of the synthesized compounds has been carried out against various human cancer cell lines, and some of the analogues are found to be potent. 相似文献
266.
Farooq Umar Hossein Raza Hamdani Anwar‐ul‐Haque Sajid Raza Chaudhry Khalid Parvez 《国际流体数值方法杂志》2009,59(2):173-194
The effect of various reduced frequencies has been examined for an oscillating aspect ratio 10 NACA 0015 wing. An unsteady, compressible three‐dimensional (3D) Navier–Stokes code based on Beam and Warming algorithm with the Baldwin–Lomax turbulence model has been used. The code is validated for the study against published experimental data. The 3D unsteady flow field is simulated for reduced frequency values of 0.1, 0.2 and 0.3 for a fixed mean angle of attack position and fixed amplitude. The type of motion is sinusoidal harmonic. The force coefficients, pressure distributions and flow visualization show that at the given conditions the flow remains attached to the wing surface even at high angles of attack with no clear separation or typical light‐to‐deep category of dynamic stall. Increased magnitude of hysteresis and higher gradients are seen at higher reduced frequencies. The 3D effects are even found at midspan locations. In addition, the rate of decrease in lift near the wing tips compared with the wing root is not much like in the static cases. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
267.
U. Örnemark Nick Boley Khalid Saeed Petronella M. van Berkel Rainer Schmidt Michael Noble Irma Mäkinen Mauri Keinänen Adam Uldall Heidi Steensland Adriaan Van der Veen Daniel W. Tholen Manfred Golze Jytte Molin Christensen Paul De Bièvre E. W. B. De Leer 《Accreditation and quality assurance》2001,6(4-5):140-146
Working group (WG) discussions on proficiency testing (PT) held at the joint Eurachem/ EQALM workshop, Borås, Sweden, 24–26 September 2000 are summarized. The discussions focused on aspects of PT and accreditation (WG 1), general aspects of PT in analytical chemistry (WG 2), microbiology (WG 3), and laboratory medicine (WG 4), incorporation of measurement uncertainty into PT schemes (WG 5), international harmonization of PT schemes (WG 6), and the role of PT in the international structure of chemical measurement (WG 7). Current status, problems and future directions are identified. Each WG contained a majority of participants experienced in the subject being covered by that WG, and a few participants with different expertise. This was done to promote cross-fertilization of ideas between sectors, a key objective of the workshop. The WG issues reflected the content of the keynote lectures and some issues were covered from different perspectives by more than one group. 相似文献
268.
A simple and rapid GC-MS method for separation, identification and quantitative determination of combustion products of organophosphorus and chlorine pesticides viz; monocrotophos, chloropyriphos, butachlor and benzenehexachloride has been developed. The method provides a positive means of identifying organic combustion products and enables to assess not only their toxicity to human beings but also their impact on the environment. The data is useful for emergency preparations in case of fire in chemical plants and warehouses that store pesticides in large quantities. 相似文献
269.
New steroidal alkaloids from Fritillaria imperialis and their cholinesterase inhibiting activities 总被引:3,自引:0,他引:3
Atta-Ur-Rahman Akhtar MN Choudhary MI Tsuda Y Sener B Khalid A Parvez M 《Chemical & pharmaceutical bulletin》2002,50(8):1013-1016
Two new cevanine steroidal alkaloids, impericine (1) and forticine (2) along with known bases delavine (3), persicanidine A (4), and imperialine (5) were isolated from the bulbs of Fritillaria imperialis. The structures of impericine (1) [(20R,22S,25S)-5alpha-cevanin-23-ene-3beta,6beta,16beta-triol] and forticine (2) [(20S,22S,25S)-5alpha-cevanine-3beta,6beta-diol] were determined with the help of spectroscopic studies. These steroidal bases showed anti-acetylcholinesterase and anti-butyrylcholinesterase inhibitory activity. 相似文献
270.
Electrochemically aided solid phase microextraction: conducting polymer film material applicable for cationic analytes 总被引:1,自引:0,他引:1
Khalid R. Temsamani Özcan Ceylan Brian J. Yates Serhan Öztemiz Thompson P. Gbatu Apryll M. Stalcup Harry B. Mark Wlodzimierz Kutner 《Journal of Solid State Electrochemistry》2002,6(7):494-497
The cation uptake and release properties of a poly(pyrrole-sulfated β-cyclodextrin) (PPy-SβCD) film electrode have been investigated
under both open circuit and controlled potential conditions for prospective applications in electrochemically aided solid-phase
microextraction (EA SPME). The EDAX and ion chromatography results show that the K+ and Na+ cation uptake is enhanced if a small negative potential is applied to the electrode in the range where PPy is in its neutral
form. These cations are released rapidly from the film if the applied potential is switched to the value at which PPy is converted
to its positively charged form, i.e., oxidized state. The cation ingress and egress mechanism is affected both by the cation
exchange at the negative sulfate moiety on the cyclodextrin sites and electrostatic interactions generated by the applied
potential. The electrochemical "switching" capability increases the speed of the cation uptake and release, presumably due
to electro migration, as compared to the open circuit ion exchange which is controlled solely by diffusion. Our preliminary
fundamental results show that the PPy-SβCD film is suitable for the future design of EA SPME devices.
Electronic Publication 相似文献