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21.
Methods have been developed to allow applications of membrane introduction mass spectrometry (MIMS) to monitor solution phase components of fermentation broths using electron ionization. The solutions are transported by flow injection analysis (FIA) through a direct insertion membrane probe, fitted with a silicone membrane in the sheet configuration. Analytes of interest pass through the membrane and are ionized by electron implant ionization. The compounds monitored are ammonia, acetic acid, and ethanol, with ammonia being detected as the monochloramine derivative which is generated at pH 10 upon addition of hypochlorite. Quantitation is achieved using external standard solutions. The dynamic range for the quantification of ammonia is 2-8000 ppm, and for ethanol and acetic acid 10-1000 ppm. This method provides rapid detection of analytes of interest, on-line monitoring capabilities, and the advantage of electron ionization. The introduction of samples into the mass spectrometer is achieved readily and automatically, the response time is a few seconds, and there are no memory effects. 相似文献
22.
A. G. Pramanik P. K. Choudhury 《Journal of polymer science. Part A, Polymer chemistry》1968,6(5):1121-1134
Sodium amylose xanthate has been studied in dilute solution. Potato starch was fractionated for this purpose into amylose and amylopectin fractions. Amylose was xanthated in solution under alkaline conditions and the Na amylose xanthate was then characterized by reaction with I2 solution and ultraviolet spectra of the xanthate groups determined. Stability of the xanthate in alkaline condition under both oxygen and nitrogen atmospheres was also investigated. From light scattering measurements of dilute salt solutions of Na amylose xanthate, the weight-average molecular weight M w as well as the molecular dimensions were determined. In 0.11M NaCl, which conforms to the θ solvent, Na amylose xanthate molecules appear to have a random-coil configuration. Two other configurational parameters, such as the effective bond length b, and the steric factor σ, i.e., (R02)1/2/(Rf2 )1/2, where (R02)1/2 is the Root-mean-square end-to-end distance in the unperturbed state and (Rf2 )1/2 is the unperturbed value calculated on the assumption of free rotation about each intermonomer C? O bond of the amylose chain were also calculated and found to be 6.24 and 1.020, respectively. It is thus concluded that the amylose chain in Na amylose xanthate behaves as a typical flexible coil in dilute salt solution. 相似文献
23.
Gurucharan Mukherjee Sailendra Nath Poddar Kingshuk Choudhury Kamalendu Dey 《Transition Metal Chemistry》1988,13(1):58-63
Summary Iron(III) complexes of a quadridentate N2S2 donor ligand, 1,2-di(o-aminophenylthio)ethane (DAPTE) and its Schiff Base with salicylaldehyde, a hexadentate N2S2O2 donor ligand,viz. 1,2-di(o-salicylaldiminophenylthio)ethane (H2DSALPTE) have been synthesised and characterised.The Schiff base ligand (1 mol) gave a dark green tri-iron(III) [Fe3(DSALPTE)(HDSALPTE)Cl3]Cl2 complex when reacted with anhydrous iron(III) chloride (1 mol). The Mössbauer data of this complex suggest the presence of three iron sites, one of which is octahedral and the other two tetrahedral. On the other hand, Fe(ClO4)3 reacted smoothly with H2DSALPTE in ethanol to give a mononuclear pseudo-octahedral complex in which the ligand functions in a dibasic hexadentate fashion. Mössbauer data suggest the presence of a low-spin-high-spin equilibrium in the solid state. The manganese(III) and cobalt(III) complexes of the Schiff base, H2DSALPTE, are also studied for the sake of comparison with the corresponding iron(III) complex. The N2S2 ligand, however, formed a low-spin pseudo-octahedral iron(III) complex. The complexes have been characterised by elemental analysis, molar conductance values, cryomagnetic data and i.r., electronic and Mössbauer spectral data. 相似文献
24.
25.
We present exact explicit expressions for the row spin-spin correlation functions
00
n0 in the isotropicd= 2 Ising model, in terms of elliptic integrals, forn 5. We also give a general structural formula for
00
n0. 相似文献
26.
Photoaffinity labeled (3-diazoacetoxy)-9-cis-retinal (1) and (9-methylenediazoacetoxy)-9-cis-retinal (20) were synthesized and bound to absorption maxima at 465 and 460 nm respectively. Binding studies established that synthetic retinals 1 and 2 bind to the natural binding site and that the integrity of the diazoacetoxy photoaffinity label is preserved in the process. Incorporation of 3-(O14COCHN2)-labeled 9-cis retinal could be conveniently carried out in high yield using apomembrane solubilized in CHAPS as detergent to afford the pigment analog in a pure form. Photolysis of the diazoacetoxy group within the binding site led to 15–20%, crosslinking of rhodopsin as estimated by using radiocarbon containing labeled retinal 1 thus showing that this synthetic retinal is suitable for photoaffinity labeling of the active site in rhodopsin. Subsequent experiments to establish the site(s) of crosslinking by sequencing studies will then contribute to our knowledge of the structure of rhodopsin. 相似文献
27.
The reaction of 2-arylpyridinecarboxaldimine [RH4C6NC(H)Py, L (1)] with hydrated RuX3 (X = Cl, Br) in boiling C2H5OH affords dark crystals of RuX2L2. Two geometrical isomers of the compound have been isolated and characterized by analytical and spectroscopic data. The trans isomer of RuCl2L2 shows a single sharp band for ν(Ru---Cl), whereas two bands are observed for the corresponding cis isomer. The highresolution 1H NMR spectra of the isolated complexes are reported and completely assigned. All the complexes have multiple t2→π*(L) transitions in the visible region. Each of the complexes display a quasi-reversible oxidative response due to an RuIII/RuII couple in the range 0.25–0.40 V vs S.C.E. at a platinum working electrode. The formal potentials of this couple obey the Hammett relationship. The ligand-based irreversible oxidations are also briefly noted. 相似文献
28.
Brajagopal Samanta Joy Chakraborty C. R. Choudhury S. K. Dey D. K. Dey S. R. Batten P. Jensen Glenn P. A. Yap Samiran Mitra 《Structural chemistry》2007,18(1):33-41
We have reported herein the synthesis of three new Cu(II) complexes of tri- and tetradentate Schiff base ligands containing
N3 or N4 donor set along with terminal NNN− or SCN− ligands: [L1Cu(NCS)]ClO4 (1), [L2Cu(NCS)2] (2) and [L3Cu(NNN)]ClO4 (3) [L1 = NC5H4C(CH3)=N(CH2)3N=C(CH3)C5H4N, L2= Me2N–(CH2)3–N=C(CH3)C5H4N and L3 = NC5H4CH=N–(CH2)4–N=CHC5H4N]. The complexes have been systematically characterised by elemental, spectroscopic and electrochemical techniques. Antimicrobial
activities of the Schiff base ligands and their metal complexes have been studied using the disc diffusion method on the strains
of Candida tropicalis and Bacillus megaterium. Structures of all the complexes have been unequivocally established from single crystal X-ray diffraction analyses that
show the monomeric units containing a five-coordinated copper center in highly distorted square pyramidal geometry with thiocyanate
or azide anion coordinated as terminal ligand. The complexes 1 and 3 crystallise in monoclinic (P21/c) and 2 in triclinic (P-1) space group, respectively. 相似文献
29.
Amitava Choudhury Larisa A. Polyakova Ingo Hartenbach Thomas Schleid Peter K. Dorhout 《无机化学与普通化学杂志》2006,632(15):2395-2401
Four related quaternary compounds containing rare‐earth metals have been synthesized employing the molten flux method and metathesis. The reactions of Eu and Rb2S5 with Si and Ge in evacuated fused silica ampoules at 725 °C for 150 h yielded RbEuSiS4 ( I ) and RbEuGeS4 ( II ), respectively. On the other hand, a reaction between CeCl3 and K4Ge4Se10 at 650 °C for 148 h has yielded KCeGeSe4 ( III ) and KPrSiSe4( IV ) was obtained by the reaction of elemental Pr, Si and Se in KCl flux at 850 °C for 168 h. Crystal data for these compounds are as follows: I , orthorhombic, space group P212121 (#19), a = 6.392(1), b = 6.634(2), c = 17.001(3) Å, α = β = γ = 90°, Z = 4; II , monoclinic, space group P21/m (#11), a = 6.498(2), b = 6.689(3), c = 8.964(3) Å, β = 108.647(6)°, Z = 2; III , monoclinic, space group P21 (#4), a = 6.852(2), b = 7.025(2), c = 9.017(3) Å, β = 108.116(2)°, Z = 2; IV , monoclinic, space group P21 (#4), a = 6.736(2), b = 6.943(2), c = 8.990(1) Å, β = 108.262(2)°, Z = 2. The crystal structures of I ‐ IV contain two‐dimensional corrugated anionic layers of the general formula, [LnEQ4]? (Ln = Ce, Pr, Eu; E = Si, Ge and Q = S, Se) alternately piled upon layers of alkali cations. In addition to structural elucidation, Raman and UV‐visible spectroscopy, and magnetic measurements for compound III (KCeGeSe4) are also discussed. 相似文献
30.
Various alcohols and phenols can be smoothly converted to the corresponding THP ethers using 20 mol % CuSO4·5H2O under mild reaction conditions at room temperature. Some of the major advantages of this procedure are nonaqueous work-up, very good yields, less expensive catalyst and compatibility with other protecting groups. 相似文献