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71.
溶剂聚合膜pH电极作内电极的气敏电极的研究 总被引:1,自引:0,他引:1
研究了以中性载体为活性物的石墨内导平头溶剂聚合膜(SPM)pH电极作内电极的二氧化碳和氨气敏电极。电极的性能取决于中性载体的特性,其中以菸酸十八酯为内电极膜活性物的二氧化碳气敏电极和以二辛基十八胺为活性物的氨气敏电极性能较佳。二氧化碳气敏电极用作丙酮酸脱羧酶酶电极的原电极,其性能院于传统的以玻璃pH电极作内电极的二氧化碳气敏电极。 相似文献
72.
New secondary and tertiary amine borane derivatives were prepared in a one-pot reaction starting from primary amine boranes. The reaction involves treatment of an amine borane with 2 equivalents of s-BuLi at −78 °C. In general, mixtures of mono and di metallated products were obtained. Alkyl iodides and benzyl chloride reacted with the lithiated amine, but aldehydes and ketones were reduced. Conversion was high as determined by NMR, but moderate to low yields were obtained after chromatography, possibly due to decomposition on silica. Crystal structures were obtained for the compounds 3a, 3b and 3c. 相似文献
73.
74.
Cao Ningjun Xia Youkun Gong Cheng S. Tsao George T. 《Applied biochemistry and biotechnology》1997,(1):129-139
A simple and effective method of treatment of lignocellulosic material was used for the preparation of corn cob for the production
of 2,3-butanediol byKlebsiella oxytoca ATCC 8724 in a simultaneous saccharification and fermentation process. During the treatment, lignin, and alkaline extractives
were solubilized and separated from cellulose and hemicellulose fractions by dilute ammonia (10%) steeping. Hemicellulose
was then hydrolyzed by dilute hydrochloric acid (1%, wJv) hydrolysis at 100°C at atmospheric pressure and separated from cellulose
fraction. The remaining solid, with 90% of cellulose, was then used as the substrate. A butanediol concentration of 25 g/L
and an ethanol concentration of 7 g/L were produced byK. oxytoca from 80 g/L of corn cob cellulose with a cellulase dosage of 8.5 IFPU/g corn cob cellulose after 72 h of SSF. With only dilute
acid hydrolysis, a butanediol production rate of 0.21 g/L/h was obtained that is much lower than the case in which corn cob
was treated with ammonia steeping prior to acid hydrolysis. The butanediol production rate for the latter was 0.36 g/L/h. 相似文献
75.
De La Rosa Luis B. Reshamwala Sultan Latimer Vivian M. Shawky Bahaa T. Dale Bruce E. Stuart Earnest D. 《Applied biochemistry and biotechnology》1994,(1):483-497
The herbaceous crops that may provide fermentable carbohydrates for production of fuels and chemicals also contain 10–20%
protein. Protein coproduction with biomass-derived fuels and chemicals has important advantages: (1) food and fuel production
can be integrated, and (2) protein is a high-value product that may significantly improve overall process economics. We report
the results of an integrated approach to producing protein and fermentable sugars from one herbaceous species, Coastal Bermudagrass
(CBG). The ammonia fiber explosion (AFEX) process makes possible over 90% conversion of cellulose and hemicellulose to simple
sugars (about 650 mg reducing sugars/g dry CBG) at 5 IU cellulase/g vs < 20% conversion for untreated CBG. The AFEX treatment
also improves protein extraction from CBG; over 80% protein recovery is possible from AFEX-treated CBG vs about 30% recovery
from untreated CBG. 相似文献
76.
Toshinobu Korenaga 《Journal of fluorine chemistry》2007,128(5):557-561
A pentafluorophenyl group can act as a stereo-controlling group in oxazaborolidine-catalyzed asymmetric borane reduction through intramolecular π-π stacking interaction with a phenyl group. The intramolecular π-π interaction in oxazaborolidine bearing pentafluorophenyl group is confirmed by calculations and 1H NMR study. The interaction affects the enantioselectivity of the asymmetric reduction of acetophenone while the extent is small. 相似文献
77.
In recent years, many optically active β-amino alcohols, mostly derived from naturally occurring α-amino acids, have been incorporated into the asymmetric synthesis as chiral auxiliaries or ligands.1 An effective asymmetric catalysts, the oxazaborolidine-borane reagents, which were originally pioneered by Itsuno and Corey,2 were generally prepared from chiral β-amino alcohols by the reaction with boric acid or formed in situ in the presence of borane. These reagents provide excellent enanti… 相似文献
78.
Pentafluorophenyliodine(III) Compounds. 2. Fluorine-Aryl Substitution Reactions on Iodinetrifluoride: Synthesis of Pentafluorophenyliodinedifluoride C6F5IF2 and Bis(pentafluorophenyl)iodonium Pentafluorophenylfluoroborates[(C6F5)2I]+[(C6F5)nBF4?n]? Mono- and disubstitution can be achieved in the fluorine-aryl substitution reaction on the low-temperature phase IF3 in CH2Cl2 at ?78°C depending on the aryl transfer reagent. With B(C6F5)3 [(C6F5)2I]+ [(C6F5)nBF4?n]? (68% yield) and with Cd(C6F5)2 C6F5IF2 (97% yield) is obtained whereas with C6F5SiMe3 no fluorine-aryl substitution takes place on IF3 even under basic conditions (EtCN or F? addition). At ?78°C in EtCN solution IF3 does not disproportionate but attacks the solvent under formation of HF. 相似文献
79.
《Electroanalysis》2006,18(5):449-455
The direct electrochemical oxidation of ammonia in propylene carbonate is reported for the first time. The voltammetric responses at glassy carbon, boron‐doped diamond, edge and basal plane pyrolytic graphite electrodes are explored and compared with the outcome indicating that the optimum electrode substrate for analytical purposes in this solvent is glassy carbon. Proof‐of‐concept is shown for the amperometric detection of ammonia using basal plane pyrolytic graphite electrodes abrasively modified with glassy carbon spheres. Given the significantly lower vapor pressure of propylene carbonate in comparison to water the implications for extending the life‐time of practical sensors are evident. Propylene carbonate shows a wide potential window with glassy carbon electrodes permitting this approach to be used for a potential diversity of gaseous analytes. 相似文献
80.
Margaret Sequeira Dermot Diamond Antoine Daridon Jan Lichtenberg Sabeth Verpoorte N. F. de Rooij 《Trends in analytical chemistry : TRAC》2002,21(12):816-827
Progress in the development of a micro-fluidic system for colorimetric monitoring of ammonia in drinking and wastewater is described. The ultimate goal is to have a miniaturised instrument that can produce accurate, reliable measurements, is easy to operate, has minimal power consumption, and can operate autonomously for a year. In this study, the indophenol reaction is incorporated into a simple, reliable analytical micro-fluidic system. Absorbance measurements for the blue ammonia-indophenol complex formed in the micro-fluidic system are shown. A key issue is the limiting stability of hypochlorite, a reagent used in the assay. The effects of hypochlorite concentration and impurities on the stability of hypochlorite are investigated and discussed. Decomposition is shown to be very dependent on the presence of heavy-metal impurities. With low levels of these catalytic metals and careful storage, hypochlorite has been shown to be stable for over a year. 相似文献