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81.
Sanyal A Rautaray D Bansal V Ahmad A Sastry M 《Langmuir : the ACS journal of surfaces and colloids》2005,21(16):7220-7224
We show here that reaction of the fungus, Fusarium oxysporum, with the aqueous heavy-metal ions Pb2+ and Cd2+ results in the one-step formation of the corresponding metal carbonates. The metal carbonates are formed by reaction of the heavy-metal ions with CO2 produced by the fungus during metabolism and thus provide a completely biological method for production of crystals of metal carbonates. The PbCO3 and CdCO3 crystals thus produced have interesting morphologies that are shown to arise because of interaction of the growing crystals with specific proteins secreted by the fungus during reaction. An additional advantage of this approach is that the reaction leads to detoxification of the aqueous solution and could have immense potential for bioremediation of heavy metals. Under conditions of this study, the metal ions are not toxic to the fungus, which readily grows after exposure to the metal ions. 相似文献
82.
7-Ethyl-10-hydroxycamptothecin (SN-38) is an active metabolite of Irinotecan (CPT-11), an anticancer pro-drug. To support clinical pharmacokinetic studies for liposome based formulation of SN-38 (LE-SN38) in cancer patients, a rapid, simple and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the quantification of total SN-38 in human plasma. Sample preparation was carried out by one-step protein precipitation using cold acetonitrile with 0.5% acetic acid (v/v). Camptothecin was used as an internal standard (IS). Chromatographic separation of SN-38 and IS was achieved using a Synergi Hydro-RP column (C(18), 50 x 2 mm, 4 micro m), with a gradient elution of acetonitrile and 0.1% acetic acid. After ionization in electrospray source (positive ions), the acquisition was performed in the multiple reactions monitoring mode. Quantitation was accomplished using the precursor-->product ion combinations of m/z 393.1-->349.2 for SN-38 and 349.1-->305.1 for IS. The quantification limit of 0.05 ng/mL was achieved by using much lower volume (0.2 mL) of plasma and in the presence of LE-SN38. The method was validated over the concentration range of 0.05-400 ng/mL. Accuracy was within +/-12% of nominal at all concentration levels. Inter-day and intra-day precisions expressed as percentage coefficient of variation (%CVs) for quality control (QC) samples were less than 14 and 5%, respectively. 相似文献
83.
Dehestani A Lam WH Hrovat DA Davidson ER Borden WT Mayer JM 《Journal of the American Chemical Society》2005,127(10):3423-3432
Osmium tetroxide is reduced by molecular hydrogen in the presence of ligands in both polar and nonpolar solvents. In CHCl3 containing pyridine (py) or 1,10-phenanthroline (phen), OsO4 is reduced by H2 to the known Os(VI) dimers L2Os(O)2(mu-O)2Os(O)2L2 (L2 = py2, phen). However, in the absence of ligands in CHCl3 and other nonpolar solvents, OsO4 is unreactive toward H2 over a week at ambient temperatures. In basic aqueous media, H2 reduces OsO4(OH)n(n-) (n = 0, 1, 2) to the isolable Os(VI) complex, OsO2(OH)4(2-), at rates close to that found in py/CHCl3. Depending on the pH, the aqueous reactions are exergonic by deltaG = -20 to -27 kcal mol(-1), based on electrochemical data. The second-order rate constants for the aqueous reactions are larger as the number of coordinated hydroxide ligands increases, k(OsO4) = 1.6(2) x 10(-2) M(-1) s(-1) < k(OsO4(OH)-) = 3.8(4) x 10(-2) M(-1) s(-1) < k(OsO4(OH)2(2-)) = 3.8(4) x 10(-1) M(-1) s(-1). The observation of primary deuterium kinetic isotope effects, k(H2)/k(D2) = 3.1(3) for OsO4 and 3.6(4) for OsO4(OH)-, indicates that the rate-determining step in each case involves H-H bond cleavage. Density functional calculations and thermochemical arguments favor a concerted [3+2] addition of H2 across two oxo groups of OsO4(L)n and argue against H* or H- abstraction from H2 or [2+2] addition of H2 across one Os=O bond. The [3+2] mechanism is analogous to that of alkene addition to OsO4(L)n to form diolates, for which acceleration by added ligands has been extensively documented. The observation that ligands also accelerate H2 addition to OsO4(L)n highlights the analogy between these two reactions. 相似文献
84.
Munir M. Ahmad Martin R. Bryce Joan Halfpenny Larry Weiler 《Tetrahedron letters》1984,25(38):4275-4278
Bis(triphenylphosphoranylidene)ammonium iodide (PPN+I?) forms a 2:3 complex with TCNQ [(PPN)2(TCNQ)3(CH3CN)2] that provides an example of a TCNQ complex containing acetonitrile in the crystal lattice; the material is a semi-conductor with trimerised TCNQ stacks. 相似文献
85.
Diastereoisomers (1S,2R,3S)-, (1R,2R,3S)-, (1R,2S,3S)- and (1S,2S,3S)-2-methyl-1-phenyl-1,3-butanediols were prepared by simple and convenient strategies using two different chemo-enzymatic approaches for the reduction of racemic 2-methyl-1-phenyl-1,3-butanedione, both involving in situ racemization. The first method comprised a one-pot microbial reduction coupled with a chemical reduction, while in the second method, stepwise chemo-enzymatic reductions were performed. 相似文献
86.
G. A. El-Shobaky A. S. Ahmad A. N. Al-Noaimi H. G. El-Shobaky 《Journal of Thermal Analysis and Calorimetry》1996,46(6):1801-1808
Basic cobalt and copper carbonates were prepared by precipitation from solutions of their nitrates using KHCO3 at room temperature in CO2 atmosphere. The thermal decomposition of the prepared basic carbonates was studied by means of TG and DTA techniques and the phases produced were identified by XRD measurements. The products obtained at 400C were subjected to different doses of gamma-rays (40–160 M rad) and the thermal stabilities of these solids were investigated.The results obtained revealed that basic cobalt carbonate decomposed at 335C to produce Co3O4 which remained stable up to 850 and then decomposed above this temperature giving CoO which transformed into Co3O4 on cooling to room temperature. Basic copper carbonate dissociated at 290C yielding CuO which yielded Cu2O and metallic copper at 1060 and 1150C, respectively. However, the produced cuprous oxide and metallic copper solids were converted into CuO and CU2O, respectively by cooling in air to room temperature.Gamma-irradiation decreased the thermal stability of Co3O4 to an extent proportional to the dose employed. On the other hand, this treatment increased the thermal stability of both CuO and Cu2O. 相似文献
87.
Summary Potassium dihydro-bis-(1-indazolyl)borate, synthesized from potassium borohydride and indazole, has been used as a reagent to yield complexes with copper(II), nickel(II), cobalt(II), manganese(II) and iron(III) ions. From i.r. spectral studies the ligand is uninegative and bidentate and coordination occurs through the nitrogen atom at position 2 of the indazole ring system in all cases. With the sole exception of the copper(II) complex, the nitrogen atom at position 1 is also involved in forming a bridge with an adjacent metal ion. On the basis of electronic spectral studies and magnetic susceptibility measurements a distorted square planar structure involving chlorine bridges has been proposed for the copper complex. An octahedral geometry with ligand bridges for all complexes is tentatively proposed and it appears that all are polymers. 相似文献
88.
Two series of 2-(N-aryl-2-oxo-2-arylethanehydrazonoyl)-6-methyl-4(3H)-pyrimidinones 11 (12) were prepared by coupling of diazotized anilines with 2-(aroylmethylene)-1,2-dihydro-6-methyl-4(3H)-pyrimidinones 2 (3). The spectral data of such compounds together with their 3-methyl analogs 13 (14) indicated that they exist predominantly in the hydrazone tautomeric form. 相似文献
89.
Nisar Ahmad M. Akram K.P. Gill S.P. Asdaq R.M. Akhtar M. Saleem M.A. Baig 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,41(3):159-163
A narrow bandwidth ring dye laser pumped by an argon ion laser has been used to investigate the hyperfine structure of the even and odd parity levels of tantalum by optogalvanic spectroscopy in the wavelength range 5640 to 6050 Å. Seventeen transitions have been observed and eight of these have not been reported in the literature so far. These transitions involve 27 levels with 15 odd and 12 even parity configurations. The magnetic dipole hyperfine interaction constants A and the electric quadrupole interaction constants B for these levels have been computed and compared with the data available in literature. The results for the levels at 34799.71 cm?1, 26960.46 cm?1 and 19657.78 cm?1 are reported for the first time. 相似文献
90.