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161.
Crude enzyme preparations fromAureobasidium sp. strain NRRL Y-2311-1 were characterized and tested for the capacity to saccharify corn fiber. Cultures grown on xylan,
corn fiber, and alkaline hydrogen peroxide (AHP)-pretreated corn fiber produced specific levels of endoxylanase, amylase,
protease, cellulase, and other activities. Using equal units of endoxylanase activity, crude enzymes from AHP-pretreated corn
fiber cultures were most effective in saccharification. Multiple enzyme activities were implicated in this process. Pretreatment
of corn fiber with AHP nearly doubled the susceptibility of hemicellulose to enzymatic digestion. Up to 138 mg xylose, 125
mg arabinose, and 490 mg glucose were obtained per g pretreated corn fiber under conditions tested.
The use of brand or trade names may be necessary to report factually on available data. The USDA neither guarantees nor warrants
the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others
that may also be suitable. All programs and services of the USDA are offered on a non-discriminatory basis without regard
to race, color, national origin, religion, sex, age, marital status, or handicap. 相似文献
162.
163.
Given a random sample from a continuous variable, it is observed that the copula linking any pair of order statistics is independent of the parent distribution. To compare the degree of association between two such pairs of ordered random variables, a notion of relative monotone regression dependence (or stochastic increasingness) is considered. Using this concept, it is proved that for i<j, the dependence of the jth order statistic on the ith order statistic decreases as i and j draw apart. This extends earlier results of Tukey (Ann. Math. Statist. 29 (1958) 588) and Kim and David (J. Statist. Plann. Inference 24 (1990) 363). The effect of the sample size on this type of dependence is also investigated, and an explicit expression is given for the population value of Kendall's coefficient of concordance between two arbitrary order statistics of a random sample. 相似文献
164.
This paper considers quantum communication involving an ensemble of states. Apart from the von Neumann entropy, it considers other measures one of which may be useful in obtaining information about an unknown pure state and another that may be useful in quantum games. It is shown that under certain conditions in a two-party quantum game, the receiver of the states can increase the entropy by adding another pure state. 相似文献
165.
We apply the Column Construction Method (Varadarajan et al., Proceedings of the Fifteenth Annual ACM-SIAM Symposium On Discrete
Algorithms, pp. 562–571, 2004) to a minimal clique cover of an interval graph to obtain a new proof that First-Fit is 8-competitive for online coloring
interval graphs. This proof also yields a new discovery that in each minimal clique cover of an interval graph G, there is a clique of size . 相似文献
166.
An enzymatic membrane reactor (EMR) for enantioseparation of (R,S)-ketoprofen via Candida antarctica lipase B (CALB) as biocatalyst was investigated. A comparative study of free and immobilized CALB was further conducted. The catalytic behaviour of CALB in an EMR was affected by the process parameters of enzyme load, substrate concentration, substrate molar ratio, lipase solution pH, reaction temperature, and substrate flow rate. Immobilization of CALB in the EMR was able to reduce the amount of enzyme required for the enantioseparation of (R,S)-ketoprofen. Immobilized CALB in the EMR assured higher reaction capacity, better thermal stability, and reusability. It was also found to be more cost effective and practical than free CALB in a batch reactor. 相似文献
167.
A highly convergent total synthesis of bitungolide F leading to the assignment of its absolute stereochemistry is described. The key steps include a Horner-Wadsworth-Emmons olefination to construct the C7-C8 bond, a Wittig reaction to introduce the conjugate E,E-olefinic moiety in the molecule, and finally a ring-closing metathesis reaction to construct the six-membered alpha,beta-unsaturated delta-lactone of the molecule. Modified Evans's syn-aldol reaction, using Crimmins's protocol, was used to install the stereochemistries at the C4 and C5 centers. The stereochemistry at C9 was introduced by means of hydroxy-directed reduction of the C9 keto using Evans's protocol. 相似文献
168.
Stereoselective synthesis of the fully protected 18-membered macrocyclic lactones as the immediate precursors of the natural products, sorangiolides A and B, is described. The key steps used in the synthesis include the sp3-hybridized carbon-carbon Fu cross coupling, the stereoselective Evans' aldol reaction with 1,5-anti induction, the 1,3-diastereoselective syn reduction of a beta-hydroxyketone intermediate, and Mukaiyama macrolactonization reactions. 相似文献
169.
Basak A Roy SK Das S Hazra AB Ghosh SC Jha S 《Chemical communications (Cambridge, England)》2007,(6):622-624
The spontaneous activation of a nonaromatic enediynyl azide under ambient conditions has been demonstrated. The aromatic enediyne followed the expected cycloaddition with the alkene in the neighbouring arm to form a stable bridged bicyclic enediyne. 相似文献
170.
(R)‐2,3‐Cyclohexylideneglyceraldehyde,a Chiral Pool Synthon for the Synthesis of 2‐Azido‐1,3‐diols
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Abdul Rouf Mushtaq A. Aga Brijesh Kumar Subhash C. Taneja 《Helvetica chimica acta》2015,98(6):823-833
A new approach was proposed for the synthesis of 2‐azido‐1,3‐diols from easily available and inexpensive chiral pool synthon (R)‐2,3‐O‐cyclohexylidene‐D ‐glyceraldehyde, through Mitsunobu azidation of 1,2‐diols. Both C(2) and C(1) azides in variable ratios were obtained in alkyl substituted diols with C(2) as the major one. 相似文献