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31.
Sadia Naureen Fatima Ijaz Areesha Nazeer Faryal Chaudhry Munawar Ali Munawar Misbahul Ain Khan 《合成通讯》2017,47(16):1478-1484
An efficient, convenient green approach for the synthesis of indole-based 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles by multicomponent reaction of substituted 2-arylindole-3-carbaldehydes, benzil, substituted anilines, and ammonium acetate using catalytic amino acid (glycine) in ethanol is described. Several amino acids have also been evaluated as organic catalysts for these reactions. The structures of the compounds have been established on the basis of infrared, mass, and 1H NMR spectral data. The mild reaction conditions, inexpensive/economical reagents, and good yield show the usefulness of this approach. 相似文献
32.
Khaula Shirin Saima Imad Sheraz Shafiq Kaneez Fatima 《Journal of Saudi Chemical Society》2010,14(1):97-100
Withania somnifera (family Solanaceae) has been studied to determine major and trace elements and their possible correlation with therapeutic value of the plant. Nine trace elements were determined in Withania somnifera. This important medicinal plant was found to be rich in Fe, Cu, Ni, Mn, and Zn. These trace elements are well known for curing diseases. The plant contains nutrient elements, which are best sources for fodder. 相似文献
33.
34.
Application of Monte Carlo simulation method to polymerization kinetics over Ziegler–Natta catalysts
In the current work, the Monte Carlo simulation method was applied to ethylene polymerization over Ziegler–Natta catalysts. As expected, polymerization over each center of a Ziegler–Natta catalyst leads to a polymer having a Schultz–Flory molecular weight distribution. Notwithstanding, the total molecular weight distribution obtained by all catalyst centers together is at least twice as broad as that of each center. As another interesting finding, the introduction of hydrogen to the reaction deactivates the catalyst active centers and thereby reduces the catalyst activity. Nevertheless, it does not mainly affect the polymerization kinetics. In addition, the polymer molecular weight falls as hydrogen is added to the reaction since it acts as a strong transfer agent. The same effect is seen when cocatalyst concentration increases. Hydrogen also widens the polymer molecular weight distribution. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 45–56, 2009 相似文献
35.
L.A. Salami 《International Journal of Heat and Fluid Flow》1984,5(3):155-165
One of the most important factors determining the shape of the calibration curve for a given turbine meter is the change in the upstream velocity distribution with flowrate. A theoretical model is evolved which can be used to predict the effects of velocity profile, viscosity and swirl on the calibration curve. It has also been used to explain the calibration curve of a commercial meter having a geometry very different from that for which the theory was developed. The effect of different types of integral flow straighteners on turbine meters is also investigated and found to depend on both the number of vanes and their length. A correlation is suggested for radial-vaned flow-straighteners 相似文献
36.
Matthew A. Bedics Hayleigh Kearns Jordan M. Cox Sam Mabbott Fatima Ali Neil C. Shand Karen Faulds Jason B. Benedict Duncan Graham Michael R. Detty 《Chemical science》2015,6(4):2302-2306
Surfaced enhanced Raman scattering (SERS) nanotags operating with 1280 nm excitation were constructed from reporter molecules selected from a library of 14 chalcogenopyrylium dyes containing phenyl, 2-thienyl, and 2-selenophenyl substituents and a surface of hollow gold nanoshells (HGNs). These 1280 SERS nanotags are unique as they have multiple chalcogen atoms available which allow them to adsorb strongly onto the gold surface of the HGN thus producing exceptional SERS signals at this long excitation wavelength. Picomolar limits of detection (LOD) were observed and individual reporters of the library were identified by principal component analysis and classified according to their unique structure and SERS spectra. 相似文献
37.
Fatima Javed Saqib Ali Saira Shahzadi Nasir Khalid Saira Tabassum Imran Khan Saroj K. Sharma Kushal Qanungo 《中国化学会会志》2015,62(8):728-738
New organotin(IV) complexes have been synthesized by treating potassium o‐isopropyl carbonodithioate with R2SnCl2/R3SnCl in 1 : 2/1 : 1 M/L ratio. All complexes have been characterized by IR and NMR (1H, 13C) spectroscopy. IR results shows that ligand acts as bidentate which is also confirmed by semi‐empirical study. NMR data reveals four coordinated geometry in solution. Computed positive heat of formation shows that complex 5 is thermodynamically unstable. UV/visible spectroscopy was used to assess the mode of interaction and binding of the complexes with DNA which shows that complex 5 exhibits higher binding constant as compared to complex 3 . In protein kinase inhibition assay, compound 3 was found most active, while other biological activities shows that triorganotin(IV) complexes are biologically more active as compared to diorganotin(IV) complexes. 相似文献
38.
Macrocyclic Gd3+ Complexes with Pendant Crown Ethers Designed for Binding Zwitterionic Neurotransmitters
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Dr. Fatima Oukhatar Hervé Meudal Dr. Céline Landon Prof. Dr. Nikos K. Logothetis Prof. Dr. Carlos Platas‐Iglesias Priv.‐Doz. Dr. Goran Angelovski Dr. Éva Tóth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):11226-11237
A series of Gd3+ complexes exhibiting a relaxometric response to zwitterionic amino acid neurotransmitters was synthesized. The design concept involves ditopic interactions 1) between a positively charged and coordinatively unsaturated Gd3+ chelate and the carboxylate group of the neurotransmitters and 2) between an azacrown ether appended to the chelate and the amino group of the neurotransmitters. The chelates differ in the nature and length of the linker connecting the cyclen‐type macrocycle that binds the Ln3+ ion and the crown ether. The complexes are monohydrated, but they exhibit high proton relaxivities (up to 7.7 mM ?1 s?1 at 60 MHz, 310 K) due to slow molecular tumbling. The formation of ternary complexes with neurotransmitters was monitored by 1H relaxometric titrations of the Gd3+ complexes and by luminescence measurements on the Eu3+ and Tb3+ analogues at pH 7.4. The remarkable relaxivity decrease (≈80 %) observed on neurotransmitter binding is related to the decrease in the hydration number, as evidenced by luminescence lifetime measurements on the Eu3+ complexes. These complexes show affinity for amino acid neurotransmitters in the millimolar range, which can be suited to imaging concentrations of synaptically released neurotransmitters. They display good selectivity over non‐amino acid neurotransmitters (acetylcholine, serotonin, and noradrenaline) and hydrogenphosphate, but selectivity over hydrogencarbonate was not achieved. 相似文献
39.
Studies and X‐ray Determinations with 2‐(Acetonylthio)benzothiazole: Synthesis of 2‐(Benzothiazol‐2‐ylthio)‐1‐phenylethanone and 2‐(Acetonylthio)Benzothiazole by C―S Bond Cleavage of 2‐(Acetonylthio)benzothiazole in KOH
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New route for the synthesis of 2‐(benzothiazol‐2‐ylthio)‐1‐phenylethanone ( 6 ) and 2‐(acetonylthio)benzothiazole ( 1 ) by using phenacyl bromide and α‐chloroacetone, respectively, through carbon–sulfur bond cleavage reactions in a basic medium has been generated. Treatment of 1 with malononitrile and elemental sulfur afforded the corresponding derivative of 2‐amino‐3‐cyanothiophene ( 12 ), whereas treatment of 1 with cyanoacetohydrazide afforded the corresponding derivative of cyanoacetylhydrazone derivative ( 13 ). The structure of the synthesis compounds has been established on the basis of elemental analyses, 1H‐NMR, 13C‐NMR, correlation spectroscopy, heteronuclear single quantum coherence, MS spectra, and X‐ray crystallographic investigations. 相似文献
40.
Dielectrophoresis (DEP) has been used for many years for the analysis of the electrophysiological properties of cells. However, such analyses have in the past been time-consuming, such that it can take 30 min or more to collect sufficient data to make valid interpretations from a single DEP spectrum. This has limited the application of the technology to a rapid tool for non-invasive, label-free research in areas from drug discovery to diagnostics. In this paper we present the development of a programmable, multi-channel DEP system for rapid biophysical assessment of populations of biological cells. A new assay format has been developed for continuous near-real-time monitoring, using simultaneous application of up to eight alternating current electrical signals to independently addressable dot microelectrodes in an array format, allowing a DEP spectrum to be measured in 20?s, with a total cycle time between measurements of 90?s. To demonstrate the system, human leukaemic K562 cells were monitored after exposure to staurosporine and valinomycin. The DEP response curves showed the timing and manner in which the membrane properties changed for the actions of these two drugs at the early phase of induction. This technology shows the great potential for increasing our understanding of the role of electrophysiology in drug action, by observing the changes in electrical characteristics as they occur. 相似文献