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181.
Paul G. Apen Paul G. Rasmussen 《Journal of polymer science. Part A, Polymer chemistry》1992,30(2):203-210
A novel betaine internal salt ( 3 ) has been synthesized by the reaction of pyridine with 1-methyl-2-bromo-4,5-dicyanoimidazole ( 1 ). The reaction of pyridine with 1 serves as a model for the reaction of poly(4-vinylpyridine) with 1 . The reaction of poly(4-vinylpyridine) with 1 gives betaine salt substituted polymers which were characterized by IR, NMR, UV-visible spectroscopy, and viscometry. The substituted polymers were compared to the model compound ( 3 ) and to unsubstituted poly(4-vinylpyridine) in order to determine polymer structure and the degree of substitution. One of the substituted polymers shows polyelectrolyte behavior. Thermal characterization of the substituted polymers shows two exothermic transitions at 260 and 340°C attributed to chemical reactions of the pendant groups. 相似文献
182.
A sensitive and selective method for the determination of pholcodine and its metabolites in urine using capillary gas chromatography with nitrogen detection is described. The procedure includes enzymatic hydrolysis of urine by beta-glucuronidase and sample pretreatment on C2 solid-phase extraction columns. Validation of the method showed good sensitivity, precision and reproducibility. The method was useful for the study of pholcodine metabolism in man. Pholcodine was found to conjugate with glucuronic acid. Morphine was identified as a metabolite and another unidentified metabolite was also detected. 相似文献
183.
Alan R. Katritzky Richard D. Tarr Steven M. Heilmann Jerald K. Rasmussen Larry R. Krepski 《Journal of polymer science. Part A, Polymer chemistry》1988,26(12):3323-3336
The following reactions of pyrylium salts with amines are described: (1)bis(pyrylium salts) with amines; (2) diamines with pyrylium salts; and (3) bis(pyrylium salts) with diamines. Both (1) and (2) give bis(pyridinium salts) in high yields, and (3) gives the corresponding polymers which are isolated and characterized. This procedure was applied to cationic bis(pyrylium salts) to give cationic dimers and polymers, and further to zwitterionic bis(pyrylium salts) to yield the corresponding zwitterionic dimers and polymers. 相似文献
184.
Paul G. Rasmussen 《Transition Metal Chemistry》1986,11(11):416-418
Summary The far-i.r. and Raman spectra of a closely related group ofpseudo-tetrahedral complexes of general formula [MX2EDM] are reported (M = CoII, NiII, CuII, ZnII; X = Cl or Br). EDM, ethylenedimorpholene, acts in these compounds as a bidentate nitrogen donor. The main skeletal vibrations are assigned under the approximate symmetry of theC
2v
(MX2Y2) point group. 相似文献
185.
Apples and other fruits are frequently cultivated in gardens and are part of our daily diet. Uptake of pollutants into apples may therefore contribute to the human daily intake of toxic substances. In current risk assessment of polluted soils, regressions or models are in use, which were not intended to be used for tree fruits. A simple model for uptake of neutral organic contaminants into fruits is developed. It considers xylem and phloem transport to fruits through the stem. The mass balance is solved for the steady-state, and an example calculation is given. The Fruit Tree Model is compared to the empirical equation of Travis and Arms (T&A), and to results from fruits, collected in contaminated areas. For polar compounds, both T&A and the Fruit Tree Model predict bioconcentration factors fruit to soil (BCF, wet weight based) of > 1. No empirical data are available to support this prediction. For very lipophilic compounds (1ogK(ow) > 5), T&A overestimates the uptake. The conclusion from the Fruit Tree Model is that the transfer of lipophilic compounds into fruits is not relevant. This was also found by an empirical study with PCDD/F. According to the Fruit Tree Model, polar chemicals are transferred efficiently into fruits, but empirical data to verify these predictions are lacking. 相似文献
186.
H H Rasmussen J van Damme M Puype B Gesser J E Celis J Vandekerckhove 《Electrophoresis》1992,13(12):960-969
Microsequencing of proteins recovered from two-dimensional (2-D) gels is being used systematically to identify proteins in the master human keratinocyte 2-D gel database. To date, about 250 protein spots recorded in human 2-D gel databases have been microsequenced and, of these, 145 are recorded in the keratinocyte database under the entry partial amino acid sequence. Coomassie Brilliant Blue-stained protein spots cut from several (up to 40) dry gels were concentrated by elution-concentration gel electrophoresis, electroblotted onto PVDF membranes and digested in situ with trypsin. Eluting peptides were separated by reversed-phase HPLC, collected individually and sequenced. Computer search using the FASTA and TFASTA programs from Genetics Computer Group indicated that 110 of the microsequenced polypeptides shared significant similarity with proteins contained in the PIR, Mipsx or GenEMBL databases. Only 35 polypeptides corresponded to hitherto unknown proteins. Peptide sequences of all 145 proteins are listed together with their coordinates (apparent molecular weight and pI) in the keratinocyte database. 相似文献
187.
Formulas are given for convergence-accelerated lattice sums over all intermolecular Coulomb, London, and repulsive interactions. Their implementation in the consistent force field is described. Optimum values of convergence constant and summation limit are found for r?12, r?9, and r?1 interaction terms. Energy minimization in all degrees of freedom, also intramolecular, for crystals of Ar, KCl, and C2H6 is reported. 相似文献
188.
Alan R. Katritzky Kumars Sakizadeh Joel Swinson Steven M. Heilmann Jerald K. Rasmussen Larry R. Krepski Sadanand V. Pathre 《Journal of polymer science. Part A, Polymer chemistry》1989,27(5):1515-1524
New polymers containing benzimidazole in the polymeric backbone were obtained from the reaction of bis(oxazolones) with known and with a novel aromatic tetraamine. The polymers have inherent viscosities in the range of 0.1-0.4 dL/g (in DMF 30°C). 相似文献
189.
D Nicoll-Griffith R Zamboni J B Rasmussen D Ethier S Charleson P Tagari 《Journal of chromatography. A》1990,526(2):341-354
BIO-Fully Automated Sample Treatment (BIO-FAST) high-performance liquid chromatography (HPLC) is a sophisticated column-switching technique in which a fresh pre-column is used for each sample prior to reversed-phase HPLC. The pre-columns, Varian Advanced Automated Sample Processor (AASP) cartridges, are held and automatically advanced by the Varian AASP. A rapid and efficient extraction and separation for leukotrienes C4 and E4 from human urine has been developed using a C8 cartridge and subsequent C18 analytical HPLC column. Quantitation of leukotriene E4, accomplished by post-column radioimmunoassay, shows significantly increased leukotriene E4 concentrations in urine samples from asthmatics after antigen challenge. This further confirms an active role for leukotrienes in the pathogenesis of bronchial asthma. 相似文献
190.
Single crystals of niobium carbonitride were made by zone melting growth methods and single crystals of γ-NbN and δ-NbN by zone annealing crystal growth. The crystals are nonstoichiometric in contrast to the niobium carbonitride or niobium nitride prepared in reaction with nitrogen gas and niobium-niobium carbide mixtures and niobium metal, respectively. The transition temperature for superconductivity (Tc) decreases with increasing deviation from stoichiometry, and a determination of Tc is a nondestructive determination of this deviation. An instrument using the Wheatstone bridge principle is described and Tc values are listed for some nonstoichiometric single crystals of niobium carbonitride and niobium nitride. 相似文献