The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Wang Xian - One of the best experts on this subject based on the ideXlab platform.
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Inhibition mechanism analysis & research of the poly Aspartic Acid corrosion inhibitor
Cleaning World, 2012Co-Authors: Wang XianAbstract:It was introduced inhibition mechanism of the poly Aspartic Acid corrosion inhibitor.Meanwhile,it was summarizeed the research progress of the inhibition mechanismf the poly Aspartic Acid corrosion inhibitor and the development trend of the poly Aspartic Acid corrosion inhibitor in this article.
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The Inhibition Mechanism Analysis & Research of the Poly Aspartic Acid Corrosion Inhibitor
2012Co-Authors: Wang XianAbstract:It was introduced inhibition mechanism of the poly Aspartic Acid corrosion inhibitor. Meanwhile, it was summarizeed the research progress of the inhibition mechanismf the poly Aspartic Acid corrosion inhibitor and the development trend of the poly Aspartic Acid corrosion inhibitor in this article.
Toyoji Kakuchi - One of the best experts on this subject based on the ideXlab platform.
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Preparation of superabsorbent hydrogels from poly(Aspartic Acid) by chemical crosslinking
Polymer Bulletin, 2011Co-Authors: Satoshi Umeda, Hiroshi Nakade, Toyoji KakuchiAbstract:Modified poly(Aspartic Acid)s containing pendant allyl groups were synthesized by the reaction of poly(succinimide) with an allyl amine in dimethylformamide. The contents of the allyl groups in the poly(Aspartic Acid) ranged from 2 to 17.4% confirmed by 1H NMR. Hydrogels were prepared using modified poly(Aspartic Acid) by chemical crosslinking using redox radical initiators including ammonium persulfate and potassium peroxodisulfate. The morphologies of the poly(Aspartic Acid)-based hydrogels were investigated by scanning electron microscopy (SEM). The water-absorbent experiments were carried out, and revealed that lightly cross-linked hydrogels resulted in effective water-absorbent properties. These results suggested that allyl group-modified poly(Aspartic Acid)s are useful in providing biodegradable hydrogels.
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Synthesis and characterization of poly(Aspartic Acid) and its derivatives as biodegradable materials
Journal of Macromolecular Science Part A, 1999Co-Authors: Takeshi Nakato, Masako Yoshitake, Masayuki Tomida, Kyoko Oda, Toyoji KakuchiAbstract:ABSTRACT Three types of modified poly(Aspartic Acid)s, such as poly(Aspartic Acid-co-aminocarboxylic Acid) (4), alkylamine modified poly(Aspartic Acid) (5) and crosslinked poly(Aspartic Acid) (6), were synthesized and calcium-ion chelating ability, hygroscopicity and water absorption were evaluated. The calcium-ion chelating ability of 4 depended on the kind of aminocarboxylic Acids and the content of aminocarboxylic Acid in the copolymer. The highest value was 3 times higher than that of poly(acrylic Acid) with a Mw of 14000. The highly modified PASP, e.g., 50 mol% lauryl amine modified poly(Aspartic Acid), showed the highest by grogroscopicity among homopoly(Aspartic Acid)s and modified poly(Aspartic Acid)s. The maximum swelling of poly(Aspartic Acid) hydrogel prepared by the γ-irradiation of homopoly(as-partic Acid) was 3400 g-deionized water/g-dry hydrogel.
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Relationships between Structure and Properties of Poly(Aspartic Acid)s
Macromolecules, 1998Co-Authors: Takeshi Nakato, Masako Yoshitake, Koshi Matsubara, Masayuki Tomida, Toyoji KakuchiAbstract:Various types of poly(Aspartic Acid)s, which were poly(α-l-Aspartic Acid), poly(α-d-Aspartic Acid), poly(β-l-Aspartic Acid), and poly(α,β-d,l-Aspartic Acid)s, were prepared, and their biodegradabilities using the OECD 301C method and calcium ion chelating abilities were measured to clarify the relationship between the structure of poly(Aspartic Acid)s and these properties. Distinct tendencies were found both between the number of amide protons and biodegradability and between the ratio of the dicarboxylic Acid end groups to the dicarboxylic Acid end group plus succinimide end group and biodegradability. The chirality of the Aspartic Acid unit and the type of amide linkage in poly(Aspartic Acid) had no apparent effect on the biodegradability of poly(Aspartic Acid). The result of repetitive biodegradability analyses for poly-Aspartic Acid suggested the complete biodegradation is possible. Regarding the calcium ion chelating ability, only the type of amide linkage affected the calcium ion chelating ability. ...
Debashree Bandyopadhyay - One of the best experts on this subject based on the ideXlab platform.
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protonation and deprotonation reaction of Aspartic Acid side chain modulated by the surrounding dielectric medium ab initio quantum chemical studies on Aspartic Acid in sixteen different solvents and two protein structures
Biophysical Journal, 2016Co-Authors: Akshay Bhatnagar, Sruthi Varanasi, Dhruv Pramod Ghiya, Chaitanya Gali Sai Ganesh, Debashree BandyopadhyayAbstract:Side chain of Aspartic Acid constitutes of carboxylate group, pKa equals to 3.7, in aqueous solution. However, large pKa shifts are often observed in protein structures. Several Aspartic Acid side chains are found in protonated form in protein NMR structures, for example, Asp26 in human thioredoxin, Asp96 in bacteriorhodopsin etc. Local micro-environment plays a crucial role in pKa shift of this amino Acid side chain. Question asked in this study - how variation in the local dielectric medium influence protonation of Aspartic Acid side chain? To answer this question, we have performed Density Functional Theory (DFT) and Moller-Plesset second order perturbation theory (MP2) calculations on Aspartic Acid side chain in 16 different implicit solvents with varying dielectric constants. These calculations show that bond order of carboxylic-OH group decreases steeply in low dielectric range (e between 1 to 9). Change in bond order within high dielectric range (e > 20) is small. This calculation suggests that carboxylic-OH bond order in Aspartic Acid side chain should be high in protein hydrophobic region (low dielectric medium) compared to protein hydrophilic region (high dielectric medium). This fact was verified from bond order, electron densities on Aspartic Acids in two different proteins, ASP96 for bacteriorhodopsin and ASP52 for hen-egg-white-lysozyme, using hybrid quantum mechanics/molecular mechanics (QM/MM) approaches. The Aspartic Acids and the surrounding hydrophobic region was treated quantum chemically and the remaining part of the proteins were treated with classical mechanics. The details of the QM/MM analyses will be discussed.
Yoshiharu Doi - One of the best experts on this subject based on the ideXlab platform.
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Enzymatic Hydrolysis of α- and β-Oligo(L-Aspartic Acid)s by Poly(Aspartic Acid) Hydrolases-1 and 2 from Sphingomonas sp. KT-1
Macromolecular Bioscience, 2004Co-Authors: Tomohiro Hiraishi, Mariko Kajiyama, Ichiro Yamato, Yoshiharu DoiAbstract:The enzymatic hydrolysis of alpha- and beta-oligo(L-Aspartic Acid)s by PAA hydrolase-1 and PAA hydrolase-2 (purified from Sphingomonas sp. KT-1) was performed to elucidate the mechanism of the microbial degradation by Sphingomonas sp. KT-1 of the thermally synthesized alpha,beta-poly(D,L-Aspartic Acid) (tPAA). GPC analysis of the hydrolyzed products of alpha- and beta-tetra(L-Aspartic Acid)s by PAA hydrolase-1 has showed that PAA hydrolase-1 is capable of hydrolyzing only the specific amide bonds between beta-Aspartic Acid units. The RP-HPLC analysis of the enzymatic hydrolysis of beta-oligo(L-Aspartic Acid)s (4 and 5 mers) by PAA hydrolase-1 has suggested that the enzymatic hydrolysis of beta-oligo(L-Aspartic Acid)s occurs via an endo-mode cleavage. In contrast, PAA hydrolase-2 hydrolyzed both alpha- and beta-oligo(L-Aspartic Acid)s via an exo-mode cleavage to yield L-Aspartic Acid as a final product. A kinetic study on the enzymatic hydrolysis of alpha-oligo(L-Aspartic Acid)s (3 to 7 mers) by PAA hydrolase-2 has indicated that Km values are almost independent of the number of monomer units in oligomers of 4 to 7 mers, while that Vmax values are markedly dependent on the chain length and show a maximum value at 5 mer.
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Poly(Aspartic Acid) Degradation by a Sphingomonas sp. Isolated from Freshwater
Applied and Environmental Microbiology, 1999Co-Authors: Kenji Tabata, Ken-ichi Kasuya, Hideki Abe, Kozue Masuda, Yoshiharu DoiAbstract:A poly(Aspartic Acid) degrading bacterium (strain KT-1 [JCM10459]) was isolated from river water and identified as a member of the genus Sphingomonas. The isolate degraded only poly(Aspartic Acid)s of low molecular masses (
I. D. Grishin - One of the best experts on this subject based on the ideXlab platform.
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Kinetics of solid phase thermal polycondensation of Aspartic Acid in evacuated system
Russian Journal of General Chemistry, 2013Co-Authors: V. A. Yablokov, Ya. A. Vasina, I. D. GrishinAbstract:Solid phase thermal polycondensation of Aspartic Acid in evacuated system results in formation of poly(Aspartic Acid) at 190–207°C and in poly(succinimide) at 210–230°C. Kinetic parameters of formation of poly(Aspartic Acid) and poly(succinimide) have been determined. The Aspartic Acid → poly(Aspartic Acid) → poly(succinimide) polycondensation is accompanied by partial decarboxylation of the monomeric units.
