Monomeric Unit , Monomer Unit, Mer

2016 ◽  
Author(s):  
A. D. Jenkins ◽  
P. Kratochvĺl ◽  
R. F. T. Stepto ◽  
U. W. Suter
Keyword(s):  
1979 ◽  
Vol 44 (1) ◽  
pp. 167-173 ◽  
Author(s):  
Slavomír Bystrický ◽  
Rudolf Kohn ◽  
Tibor Sticzay

The CD spectra of aqueous solutions of homopolymeric sodium oligogalacturonates and D-galacturonans of polymerization degree n = 1-64, as well as lower calcium oligogalacturonates (n = 1-5) were measured. Chiroptic properties were correlated with the polymerization degree in terms of optical superposition of monomeric unit increments. Interpretation of obtained data, respecting further physicochemical properties entitles to conclude that the conformation of macromolecules of D-galacturonan in solution is close to helical structure.


2021 ◽  
Author(s):  
Doyk Hwang ◽  
Cody W. Schlenker

This article highlights the photochemistry of heptazine derivatives, a structural monomer unit of carbon nitride photocatalysts.


Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1152
Author(s):  
Tatyana Kirila ◽  
Anna Smirnova ◽  
Alla Razina ◽  
Andrey Tenkovtsev ◽  
Alexander Filippov

The water–salt solutions of star-shaped six-arm poly-2-alkyl-2-oxazines and poly-2-alkyl-2-oxazolines were studied by light scattering and turbidimetry. The core was hexaaza[26]orthoparacyclophane and the arms were poly-2-ethyl-2-oxazine, poly-2-isopropyl-2-oxazine, poly-2-ethyl-2-oxazoline, and poly-2-isopropyl-2-oxazoline. NaCl and N-methylpyridinium p-toluenesulfonate were used as salts. Their concentration varied from 0–0.154 M. On heating, a phase transition was observed in all studied solutions. It was found that the effect of salt on the thermosensitivity of the investigated stars depends on the structure of the salt and polymer and on the salt content in the solution. The phase separation temperature decreased with an increase in the hydrophobicity of the polymers, which is caused by both a growth of the side radical size and an elongation of the monomer unit. For NaCl solutions, the phase separation temperature monotonically decreased with growth of salt concentration. In solutions with methylpyridinium p-toluenesulfonate, the dependence of the phase separation temperature on the salt concentration was non-monotonic with minimum at salt concentration corresponding to one salt molecule per one arm of a polymer star. Poly-2-alkyl-2-oxazine and poly-2-alkyl-2-oxazoline stars with a hexaaza[26]orthoparacyclophane core are more sensitive to the presence of salt in solution than the similar stars with a calix[n]arene branching center.


2006 ◽  
Vol 2006 (12) ◽  
pp. 2777-2785 ◽  
Author(s):  
J. René Backes ◽  
Ulrich Koert

Author(s):  
Irina A. Chetvertneva ◽  
Oleg Kh. Karimov ◽  
Galina A. Teptereva ◽  
Natalia S. Tivas ◽  
Eldar M. Movsumzade ◽  
...  

The paper considers the main components and products of wood processing, agricultural waste, pulp and paper industry waste and qualifies them as sources of pentose-containing resource-renewable domestic raw materials. The article describes in detail the structural components of wood as a natural polymer, which contains aromatic and carbohydrate parts. It is noted that these poly-mers are promising as raw materials for the production of useful chemical products. The role of lignin, cellolose and hemicellulose in the design of mechanical and structural properties of wood is considered. The article considers the features of the sulfonation reactions of the lignin monomer unit depending on the pH of the medium: acidic, neutral and alkaline. There are three main reac-tions that occur simultaneously with lignin in the process of wood delignification during sulfite cooking, such as the sulfonation reaction, the hydrolytic destruction reaction, and the condensation reaction. It is shown that the lignin-hemicellulose matrix contains three types of interconnected mesh structures: the lignin itself; a network of covalent bonds of lignin with hemicelluloses, and a network whose structure is obtained due to the hydrogen bond and the forces of the physical inter-action of lignin and hemicelluloses. The features of chemical transformations of the monomeric aromatic link of lignosulfonate – phenylpropane unit in the processes of wood delignification, the main chemical reactions of wood raw material delignification under the conditions of sulfite and neutral-sulfite brews are shown. The method of quantitative determination of monosaccharides in the composition of the carbohydrate part is proposed.


Microbiology ◽  
2021 ◽  
Vol 167 (7) ◽  
Author(s):  
Atsushi Hisatomi ◽  
Yuh Shiwa ◽  
Nobuyuki Fujita ◽  
Hiroyuki Koshino ◽  
Naoto Tanaka

Siderophores are produced by several bacteria that utilise iron in various environments. Elucidating the structure of a specific siderophore may have valuable applications in drug development. Stenotrophomonas maltophilia , a Gram-negative bacterium that inhabits a wide range of environments and can cause pneumonia, produces siderophores. However, the structure was unknown, and therefore, in this study, we aimed to elucidate it. We purified siderophores from cultures of S. maltophilia K279a using preparative reversed-phase HPLC. The structure was analysed through LC-MS and 1H and 13C NMR. The results demonstrated that S. maltophilia K279a produces 2,3-dihydroxybenzoylserine (DHBS), a monomer unit of enterobactin. We suggested the uptake of Iron(III) by the DHBS complex. DHBS production by S. maltophilia K279a could be attributed to an incomplete enterobactin pathway. Drugs targeting DHBS synthesis could prevent S. maltophilia infection.


2020 ◽  
Vol 142 (47) ◽  
pp. 20201-20207
Author(s):  
K. C. Nicolaou ◽  
Qifeng Chen ◽  
Ruofan Li ◽  
Yasuaki Anami ◽  
Kyoji Tsuchikama

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