Formation and catalytic activity of high molecular weight soluble polymers produced by heating amino acids in a modified sea medium

1982 ◽  
Vol 12 (2) ◽  
pp. 153-163 ◽  
Author(s):  
Hiroyuki Okihana
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Catalytic Activity ◽  
High Molecular Weight ◽  
Soluble Polymers

scholarly journals Catalytic Degradation of Chitosan by Supported Heteropoly Acids in Heterogeneous Systems

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1078
Author(s):  
Hang Zhang ◽  
Zhipeng Ma ◽  
Yunpeng Min ◽  
Huiru Wang ◽  
Ru Zhang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Molecular Weight ◽  
Catalytic Activity ◽  
Activated Carbon ◽  
Reaction Time ◽  
High Molecular Weight ◽  
Reaction Temperature ◽  
Water Soluble ◽  
High Catalytic Activity ◽  
High Molecular Weight Chitosan

Several kinds of composite materials with phosphotungstic acid (PTA) as the catalyst were prepared with activated carbon as support, and their structures were characterized. According to the Box–Behnken central combination principle, the mathematical model of the heterogeneous system is established. Based on the single-factor experiments, the reaction temperature, the reaction time, the amount of hydrogen peroxide and the loading capacity of PTA were selected as the influencing factors to study the catalyzed oxidation of hydrogen peroxide and degradation of high molecular weight chitosan. The results of IR showed that the catalyst had a Keggin structure. The results of the mercury intrusion test showed that the pore structure of the supported PTA catalyst did not change significantly, and with the increase of PTA loading, the porosity and pore volume decreased regularly, which indicated that PTA molecules had been absorbed and filled into the pore of activated carbon. The results of Response Surface Design (RSD) showed that the optimum reaction conditions of supported PTA catalysts for oxidative degradation of high molecular weight chitosan by hydrogen peroxide were as follows: reaction temperature was 70 ℃, reaction time was 3.0 h, the ratio of hydrogen peroxide to chitosan was 2.4 and the catalyst loading was 30%. Under these conditions, the yield and molecular weight of water-soluble chitosan were 62.8% and 1290 Da, respectively. The supported PTA catalyst maintained high catalytic activity after three reuses, which indicated that the supported PTA catalyst had excellent catalytic activity and stable performance compared with the PTA catalyst.

Direct chromatographic enantioresolution of fully constrained β-amino acids: exploring the use of high-molecular weight chiral selectors

Amino Acids ◽  
2014 ◽  
Vol 46 (5) ◽  
pp. 1235-1242 ◽  
Author(s):  
Roccaldo Sardella ◽  
Federica Ianni ◽  
Antonella Lisanti ◽  
Stefania Scorzoni ◽  
Francesca Marini ◽  
...  
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
High Molecular Weight ◽  
Chiral Selectors

scholarly journals Enhancing thermostability of iron ethylene polymerization catalysts through N,N,N-chelation of doubly fused α,α′-bis(arylimino)-2,3:5,6-bis(hexamethylene)pyridines

2019 ◽  
Vol 9 (8) ◽  
pp. 1933-1943 ◽  
Author(s):  
Zheng Wang ◽  
Randi Zhang ◽  
Wenjuan Zhang ◽  
Gregory A. Solan ◽  
Qingbin Liu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
High Molecular Weight ◽  
Ethylene Polymerization ◽  
High Catalytic Activity ◽  
Polymerization Catalysts ◽  
Fe Catalyst

At temperatures up to 80 °C, high catalytic activity and high molecular weight PE was achievable using the Fe-catalyst depicted.

scholarly journals The AMS Dating of Separate Fractions in Archaeology

Radiocarbon ◽  
1986 ◽  
Vol 28 (2A) ◽  
pp. 698-701 ◽  
Author(s):  
R J Batten ◽  
Richard Gillespie ◽  
J A J Gowlett ◽  
Rem Hedges
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Humic Acid ◽  
Carbon Source ◽  
High Molecular Weight ◽  
Complex Mixture ◽  
Small Samples ◽  
Radiocarbon Dates ◽  
Ams Dating ◽  
Relationship Of

The usefulness of radiocarbon dates in archaeology greatly depends on both the stratigraphic relationship of the sample submitted and on the origin and homogeneity of the measured carbon. For very small samples, stratigraphic relationships can raise additional problems of movement. In chemically well-characterized materials, the best example being collagen, the carbon source can be reasonably well purified. Many samples, however, survive as a complex mixture of high molecular weight polyphenolic materials, with properties between charcoals, humic acids, and lignins. Charred bone, eg, which rarely contains useful quantities of amino acids, and charred seeds, as well as ‘charcoal,’ frequently come into this category. For such samples, the likelihood of contamination by percolating soil humics is high. It is often possible to extract chemically different fractions and to compare the dates obtained. A less exact comparison can also be made for different samples from the same context. The results suggest that ‘humic’ acid dates can be reliable in a surprisingly frequent number of situations, and that where direct comparison is possible, the reliability can be individually assessed.

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