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881.
Khalid M. Tawarah Mohammad A. Khasawneh Shehadeh A. Mizyed 《Journal of inclusion phenomena and macrocyclic chemistry》2005,51(3-4):143-148
An equilibrium study concerning the association of Na+, K+, Rb+ and Cs+ with 4, 7, 13, 18-tetraoxa-1,10-diazabicyclo [8, 5, 5]-eicosane [211], 4, 7, 13, 16, 21-pentaoxa-1, 10-diazabicyclo [8, 8, 5]-tricosane [221] and 4, 13-didecyl-1, 7, 10, 16-tetraoxa-4, 13-diazacyclooctadecane [22-DD] in acetonitrile has been carried out at 25 °C by using a conductometric technique. The observed molar conductivity, Λ, of a test solution was found to decrease significantly for mole ratios less than 1:1 upon the addition of the complexing ligand. A model based on 1:1 stoichiometry has been used to analyze the conductivity data. The data have been fitted according to a non-linear least-squares analysis that provides the stability constant, K, and the molar conductivity, Λc, for each cation – ligand inclusion complex. The binding sequences were found to follow the order: Na+ > K+ > Rb+ ≫ Cs+ (K ≈ 0) for [211], Na+ > K+ > Rb+ > Cs+ for [221] and K+ > Na+ > Rb+ > Cs+ for [22-DD] complexes. Trends in ionic conductivities of complexed ions are also discussed. 相似文献
882.
Reactions of diethylphosphonoalkyl α-aminonitriles with 1,1′-carbonyl-diimidazole or 1,1′-carbonyl-di-(1,2,4-triazole) and O-substituted hydroxylamines under acidic conditions gave 3-alkoxy-4-imino-imidazolidin-2-ones, whereas in presence of triethylamine 4-alkoxy(aralkoxy)imino-imidazolidin-2-ones were formed. 相似文献
883.
884.
Aimen Khalid Dr. Asim-ur-Rehman Dr. Naveed Ahmed Iqra Chaudhery Dr. Meneerah A. Al-Jafary Prof. Ebtesam Abdullah Al-Suhaimi Dr. Mohamad Tarhini Dr. Noureddine Lebaz Dr. Abdelhamid Elaissari 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(33):8437-8451
Polysaccharides, due to their outstanding properties, have attracted the attention of researchers, working in the biomedical field and especially of those working in drug delivery. Modified/functionalized polysaccharides further increase the importance for various applications. Delivery of therapeutics for diverse ailments in different endocrine glands and hormones safely, is a focal point of researchers working in the field. Among the routes followed, the transdermal route is preferred due to non-exposure of active moieties to the harsh gastric environment and first-pass metabolism. This review starts with the overview of polysaccharides used for the delivery of various therapeutic agents. Advantages of polysaccharides used in the transdermal route are addressed in detail. Types of polysaccharides will be elaborated through examples, and in this context, special emphasis will be on the polysaccharides being used for synthesis of the membranes/films. Techniques employed for their modification to design novel carriers for therapeutics delivery will also be discussed. The review will end with a brief discussion on recent developments and future perspectives for delivery of therapeutic agents, and vaccine development. 相似文献
885.
Saira Shahzadi Moazzam H. Bhatti Khadija Shahid Saqib Ali Saadia R. Tariq Mohammad Mazhar Khalid M. Khan 《Monatshefte für Chemie / Chemical Monthly》2002,20(1):1089-1096
Tributyltin(IV) derivatives of six different pharmaceutically active carboxylates were synthesized. The complexes were characterized by different analytical techniques (elemental analysis; infrared, NMR, and mass spectroscopy). 119Sn NMR data were also recorded in six different coordinating and non-coordinating solvents. The antibacterial activities of the compounds were tested using ten different bacteria relative to the reference drugs ampicillin and cephalexin. 相似文献
886.
El-Emam AA Alrashood KA Al-Omar MA Al-Tamimi AM 《Molecules (Basel, Switzerland)》2012,17(3):3475-3483
The reaction of adamantane-1-carbohydrazide (1) with heterocyclic aldehydes, namely 5-(4-chlorophenyl)isoxazole-3-carboxaldehyde (2a), 5-(4-methylphenyl)isoxazole-3-carboxaldehyde (2b), 5-(4-methoxyphenyl)isoxazole-3-carboxaldehyde (2c), 1H-imidazole-2-carboxaldehyde and 2-butyl-4-chloro-1H-imidazole-5-carboxaldehyde, in ethanol, yielded the corresponding N'-heteroarylidene-1-adamantylcarbohydrazides 3a, 3b, 3c, 4 and 5, respectively, in good yields. The 4-acetyl-1,3,4-oxadiazoline analogues 6a?c were prepared in 48-55% yields by heating their corresponding N'-heteroarylidene-1-adamantylcarbohydrazides 3a-c with acetic anhydride for two hours. Compounds 3a-c, 4, 5 and 6a-c were tested for in vitro activities against a panel of Gram-positive and Gram-negative bacteria and the yeast-like pathogenic fungus Candida albicans. Compounds 4 and 5 displayed potent broad-spectrum antimicrobial activity, while compounds 3a-c showed good activity against the Gram-positive bacteria. 相似文献
887.
Khalid A. Rabaeh Ahmed A. Basfar Akram A. Moussa 《Radiation Physics and Chemistry》2012,81(4):479-483
Nitro blue tetrazolium polyvinyl alcohol film dosimeters, NBT-PVA were prepared and evaluated based on radiation-induced reduction of NBT2+. NBT-PVA film dosimeters containing different concentrations of NBT dye from 1 to 5 mM were prepared in a solution of ethanol. The dosimeters were irradiated with ?-ray from 60Co source at doses up to 50 kGy. UV/vis spectrophotometer was used to investigate the optical density of un-irradiated and irradiated films in terms of absorbance at 529 nm. The absorbance increases with absorbed dose up to 50 kGy for NBT-PVA film dosimeters. The dose sensitivity of NBT-PVA film increases strongly with increase of concentrations of NBT dye. The effects of irradiation temperature, humidity, dose rate and the stability of the response of the films after irradiation were investigated. A considerable increase was observed in the dose response of NBT-PVA film by adding appropriate concentration of sodium formate and Triton X-100. 相似文献
888.
Khalid Ibrahim 《European Polymer Journal》2003,39(5):939-944
The homogeneous controlled/‘living’ free radical polymerization of n-butyl methacrylate in toluene or o-xylene at 90 °C, in bulk and in solution, using the novel combination of the catalyst bis-triphenylphosphine iron(II)chloride tetrahydrate (FeCl2 · 4H2O(PPh3)2) with ethyl 2-bromoisobutyrate ((CH3)2CBrCO2Et)) and α,α-dichloroacetophenone (CHCl2COPh) as initiators has been investigated. The rate of polymerization initiated by the two initiators exhibited first-order kinetic with respect to the monomer. A linear increase of the number-average molecular weight (Mn) versus monomer conversion was observed for these systems. Among the two initiation systems, ethyl 2-bromoisobutyrate gave the fastest polymerization rate. A system with Fe3+ added at the beginning of the polymerization was examined and the lowest polydispersity (Mw/Mn∼1.2) was found when 10% Fe3+, relative to Fe2+ was added. 相似文献
889.
SA Idris K Alotaibi TA Peshkur P Anderson LT Gibson 《Journal of colloid and interface science》2012,386(1):344-349
Speciation and separation of chromium (VI) and chromium (III) from aqueous solutions were investigated using amino-propyl functionalised mesoporous silica (AP-MCM-41) as an adsorbent. The as-synthesised adsorbent was produced following a simple synthesis method at room temperature prior to template removal using microwave digestion. The maximum adsorption capacity at 111.1mg/g was calculated according to the Langmuir isotherm model, suggesting a 1:1 monolayer adsorption mechanism. Moreover, AP is a simple chelate, yet it can extract Cr (VI) exclusively from solutions containing other mixed metal ions simply by tuning the solution pH. Recovery of Cr (VI) from loaded sorbents is equally easy to perform with 100% extraction efficiencies allowing reuse of the sorbent and recovery of Cr (VI) from aqueous solutions containing a complex mixture of ions. The material would find use in environmental remediation applications, as a selective adsorbent of Cr (VI) or even as a solid-phase extraction stationary phase to remove and pre-concentrate Cr (VI) from aqueous solutions; this study demonstrates enrichment factors of 100 although higher levels are also possible. 相似文献
890.
Siddiqi ZA Kumar S Khalid M Shahid M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,71(5):1845-1850
The dipodal ligands (Im) and (BIm) as well as complexes [FeLCl3] [L = Im (1) and BIm (2)] have been prepared and studied using spectroscopic techniques. The magnetic moment, IR, electronic (ligand field), FAB-mass and NMR spectral data indicate a hexa-coordinate geometry around high-spin state Fe3+ where the ligands coordinate as a tridentate [N,N,N] chelating agent. 57Fe-Mössbauer spectral data confirmed the presence of a ligand asymmetry around Fe3+ in a high-spin state electronic configuration (t2g3,eg2, S = 5/2) with nuclear transition Fe(±3/2 → ±1/2) exhibiting Kramer's double degeneracy. The molecular computations provided the optimum energy perspective plots for the molecular geometries giving the important structural data. 相似文献