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101.
Johnston AM Scrimgeour CM Kennedy H Handley LL 《Rapid communications in mass spectrometry : RCM》2003,17(11):1099-1106
The conversion of ammonium (NH(4) (+)) to 1-sulfonato-iso-indole has been examined as a method for natural abundance measurement of delta(15)N of NH(4) (+). The reaction is complete within 2 h and is based on the derivatisation of NH(4) (+) by o-phthaldialdehyde and sodium sulfite at a high pH, 11.2. The product is readily concentrated from dilute solutions by reverse-phase solid-phase extraction (SPE). The method is compound-specific despite partial derivatisation of potentially interfering amino acids, as their derivatives are not extracted by SPE. delta(15)N values of NH(4) (+) in KCL soil extracts can be measured within 48 h by automated continuous-flow IRMS with a precision of 0.23 per thousand (1 SD). Parallel measurements of NH(4) (+) standards of known delta(15)N are made to allow correction for the isotopic dilution by non-sample NH(4) (+). The practicality of this method is demonstrated by measuring the changes in NH(4) (+) concentration and delta(15)N following the addition of urea as a nitrogen source to inorganic N-depleted soil. 相似文献
102.
103.
H. C. Öttinger 《Colloid and polymer science》1987,265(2):101-105
The idea of consistently averaging the hydrodynamic interaction and its various consequences for Hookean dumbbells are reviewed. For long chains this idea can be used to generalize the Rouse-Zimm model for polymer solutions. Unlike the usual Rouse-Zimm model, the new model for steady shear flow predicts a nonzero second normal stress coefficient and shear rate dependent material functions. In the limit of long chains, the viscosity and the normal stress coefficients are universal functions of the reduced shear rate.This paper was presented at the Frühjahrstagung des Fachausschusses Polymerphysik der Deutschen Physikalischen Gesellschaft at Kaiserslautern (West Germany), March 12–14, 1986. 相似文献
104.
An approximate electron propagator method for predictive calculations of molecular electron affinities is proposed. The self-energy accounts for relaxation effects to all orders Additional correlation effects are treated using a diagonal approximation with shifted denominators. Applications to CN, NH2, and PH2 are reported. 相似文献
105.
(1R,2R)-1,2-bis-(5-amino-1,3,4-thiadiazole-2-yl)ethane-1,2-diol (L) has been prepared by the reaction of thiosemicarbazide with (2R,3R)-(+)-tartaric
acid (I) and phosphorous oxychloride, and its complexes with Co(II), Ni(II) and Cu(II) have been obtained. The structures
of the ligand and its complexes have been established by i. r., 1H- and 13C-n.m.r. spectra, u.v.–vis–nir spectroscopy, elemental analyses, T.g.-D.t.a. and magnetic susceptibility measurements. 相似文献
106.
Takeshita N Paradis LA Oner D McCarthy TJ Chen W 《Langmuir : the ACS journal of surfaces and colloids》2004,20(19):8131-8136
Wettability was controlled in a rational manner by individually and simultaneously manipulating surface topography and surface chemical structure. The first stage of this research involved the adsorption of charged submicrometer polystyrene latex particles to oppositely charged poly(ethylene terephthalate) (PET) film samples to form surfaces with different topographies/roughness; adsorption time, solution pH, solution ionic strength, latex particle size, and substrate charge density are external variables that were controlled. The introduction of discrete functional groups to smooth and rough surfaces through organic transformations was carried out in the second stage. Amine groups (-NH(2)) and alcohol groups (-OH) were introduced onto smooth PET surfaces by amidation with poly(allylamine) and adsorption with poly(vinyl alcohol) (PVOH), respectively. On latex particle adsorbed surfaces, a thin layer of gold was evaporated first to prevent particle redistribution before chemical transformation. Reactions with functionalized thiols and adsorption with PVOH on patterned gold surfaces successfully enhanced surface hydrophobicity and hydrophilicity. Particle size and biomodal particle size distribution affect both hydrophobicity and hydrophilicity. A very hydrophobic surface exhibiting water contact angles of 150 degrees /126 degrees (theta(A)/theta(R)) prepared by adsorption of 1-octadecanethiol and a hydrophilic surface with water contact angles of 18 degrees /8 degrees (theta(A)/theta(R)) prepared by adsorption of PVOH were prepared on gold-coated surfaces containing both 0.35 and 0.1 microm latex particles. The combination of surface topography and surface-chemical functionality permits wettability control over a wide range. 相似文献
107.
Contributions to the Chemistry of Phosphorus. 143. Li4P26 and Na4P26, the First Salts with Hexacosaphosphid(4?) Ions The hexacosaphosphides Li4P26 ( 1 ) and Na4P26 ( 2 ) are formed besides other polyphosphides in the reaction of white phosphorus with lithium dihydrogenphosphide or sodium. 1 also results from the decomposition of Li2HP7 in tetrahydrofuran at room temperature and can be obtained pure as a crystalline solvent adduct Li4P26 · 16 THF. According to 2D?31P-NMR spectroscopic investigations the P264? ion is a conjucto-phosphane of two P7(5)?-and two P9(3)?-unit groups with structures analogous to norbornane and deltacyclane, respectively. 相似文献
108.
A. Ugur M. M. Saç G. Yener Ü. Altinbaş Y. Kurucu M. Bolca B. Özden 《Journal of Radioanalytical and Nuclear Chemistry》2004,259(2):265-270
Vertical distributions of 137Cs and 210Pb in soil profiles were examined to study their availability in soil erosion at Gökova region where there exists intensive agricultural activities on sloppy fields. Since the mobility of these radionuclides depend on soil characteristics, soil samples were analyzed also for their physical and chemical properties. From 137Cs inventories measured, erosion rates for cultivated and disturbed (no cultivation) soils were calculated to range from 79.1 to 6.5 t.ha-1.y-1 and from 79.9 to 3.5 t.ha-1.y-1, respectively. The 210Pb technique is found to be not suitable for erosion determination for this area, presumably due to the coal-fired power plants operating in the region. 相似文献
109.
Enright PM Tosin M Nieuwenhuyzen M Cronin L Murphy PV 《The Journal of organic chemistry》2002,67(11):3733-3741
The work described deals with the isolation and characterization of epoxides from 6-deoxyhex-5-enopyranosides and preliminary exploration of their synthetic potential. Prolonged epoxidation reaction times led to their hydrolysis in situ and gave novel protected D-hexos-5-ulose derivatives (sugar 1,5-dicarbonyls). Some reactions of the hexos-5-uloses were studied, and in some cases septanoside (seven-membered-ring saccharide) derivatives were isolated. Novel routes to D-xylo-hexos-5-ulose and D-lyxo-hexos-5-ulose, of interest as intermediates in the synthesis and biosynthesis of inositols and aza sugars, are also described. The structures of the epoxides and novel hexos-5-uloses were established by NMR and X-ray crystallographic methods. 相似文献
110.
Rotation matrices were expressed in terms of Gaunt coefficients and complex spherical harmonics. The rotation matrices were calculated using two different ways. In the first, Gaunt coefficients and normalized complex spherical harmonics were directly calculated using binomial coefficients; in the second, Gaunt coefficients and complex spherical harmonics were recursively calculated. The methods were compared with respect to accuracy and computation time (CPU) for low and very high quantum numbers. 相似文献