• Computers and Concrete
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• v.30 no.4
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• pp.269-276
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• 2022

In this paper, frequency vibrations of double-walled carbon nanotubes (CNTs) has been investigated based upon nonlocal elastic theory. The inference of small scale is being perceived by establishing nonlocal Love shell model. The wave propagation approach has been operated to frame the governing equations as eigen value system. An innovational nonlocal model to examine the scale effect on vibrational behavior of armchair, zigzag and chiral of double-walled CNTs. An appropriate selection of material properties and nonlocal parameter has been considered. The influence of dimensionless nonlocal parameter has been studied in detail. The dominance of end condition via nonlocal parameter is explained graphically. The results generated furnish the evidence regarding applicability of nonlocal shell model and also verified by earlier published literature.

• The Journal of the Convergence on Culture Technology
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• v.7 no.2
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• pp.389-394
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• 2021

In this work, we study the properties of molecular structure and boundary orbital functions of the DPHMP-AlH and propiophenone and butyrophenone, which are forms of alkoxy-amine-aluminum derivatives. Furthermore, we investigate the effect on the selective reduction of the final products (R), (S)-phenylpropanol and (R), (S)-phenylbutanol by calculating the stereoscopic and thermodynamic parameters of the transition state. Considering the three-dimensional molecular structural stability, the transition status of (S) types DPHMP-AlH and alkylphenone was found to be more stable, resulting in the selective reductions of DPHM-AlH and alkylphenone from this result: (S)-(1)-phenylpropanol and (S)-(1)-phenylbutanol was confirmed that the formation was advantageous.

• Journal of Microbiology and Biotechnology
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• v.18 no.3
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• pp.552-559
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• 2008

Ethyl (S)-4-chloro-3-hydroxybutyrate is an intermediate for the synthesis of Atorvastatin, a chiral drug used for hypercholesterolemia. A Rhodococcus erythropolisstrain (No.7) able to convert 4-chloro-3-hydroxybutyronitrile into 4-chloro-3-hydroxybutyric acid has recently been isolated from soil. This activity has been regarded as having been caused by the successive actions of the nitrile hydratase and amidase. In this instance, the corresponding amidase gene was cloned from the R. erythropolis strain and expressed in Escherichia coli cells. A soluble active form of amidase enzyme was obtained at $18^{\circ}C$. The Ni column-purified recombinant amidase was found to have a specific activity of 3.89 U/mg toward the substrate isobutyramide. The amidase was found to exhibit a higher degree of activity when used with mid-chain substrates than with short-chain ones. Put differently, amongst the various amides tested, isobutyramide and butyramide were found to be hydrolyzed the most rapidly. In addition to amidase activity, the enzyme was found to exhibit acyltransferase activity when hydroxyl amine was present. This dual activity has also been observed in other enzymes belonging to the same amidase group (E.C. 3.5.1.4). Moreover, the purified enzyme was proven to be able to enantioselectively hydrolyze 4-chloro-3-hydroxybutyramide into the corresponding acid. The e.e. value was measured to be 52% when the conversion yield was 57%. Although this e.e. value is low for direct commercial use, molecular evolution could eventually result in this amidase being used as a biocatalyst for the production of ethyl (S)-4-chloro-3-hydroxybutyrate.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.392-395
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• 2014

(2S,3S,4S)-3,4-Dihydroxyglutamic acid (DHGA), a biologically active ${\alpha},{\beta}$-dihydroxy-${\gamma}$-amino acid, was efficiently synthesized from a readily available D-serine derivative in 30% overall yield over 11 steps. The key stereoselective $OsO_4$-catalyzed dihydroxylation reaction controlled by an N-diphenylmethylene group on the amino group of ${\gamma}$-amino-${\alpha},{\beta}$-unsaturated (Z)-ester successfully introduced the diol moiety of the intermediate 5a in 86% with more than 10 : 1 diastereomeric ration. Then it was in turn successfully converted to the desired target compound, (2S,3S,4S)-3,4-DHGA, via simple oxidation and hydrolysis in a highly stereoselective manner and a higher yield than the previous syntheses. This result strongly supports that our synthetic methodology of stereoselective $OsO_4$-catalyzed dihydroxylation should be useful in stereoselctive synthesis of various bioactive compounds with an amino diol moiety.