Exopolysaccharides in biofilms, flocs and related structures

2001 ◽  
Vol 43 (6) ◽  
pp. 77-86 ◽  
Author(s):  
I. W. Sutherland
Keyword(s):  
Physical Properties ◽  
Microbial Communities ◽  
Structure And Properties ◽  
Structure And Stability ◽  
Floc Structure ◽  
Planktonic Bacteria ◽  
Accurate Picture ◽  
Composition Structure ◽  
Micro Organisms

In biofilms, flocs and similar multispecies microbial communities, exopolysaccharides (EPSs) are always present, frequently as the major component other than water. The EPSs vary widely in their composition, structure and properties and thus it is impossible to generalise about their contribution to biofilm or floc structure. Relatively few of the polymers obtained from biofilms and flocs have been adequately purified and analysed but such evidence as is so far available suggests that the polysaccharides closely resemble those synthesised by the corresponding planktonic bacteria. From a knowledge of the physical properties of these, it is now possible to present a reasonably accurate picture of some of the factors which they may contribute to the structure and stability of complex aggregates of micro-organisms in biofilms and flocs.

scholarly journals Physical Properties Of Rare Earth Elements

2021 ◽  
Vol 03 (01) ◽  
pp. 79-88
Author(s):  
Davron Rakhmonovich Djuraev ◽  
◽  
Mokhigul Madiyorovna Jamilova ◽  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Physical Properties ◽  
Phase Transformations ◽  
Rare Earth Metals ◽  
Economic Effect ◽  
Structure And Properties ◽  
Structure And Stability ◽  
Ongoing Phase

The article studies the physical properties of rare earth metals, pays special attention to their unique properties, studies the main aspects of the application of rare earth metals in industry. Also, the structure and stability of various forms of sesquioxides of rare earth elements, in particular, europium, as well as the effect of the method of oxide preparation on its structure and properties are considered. The analysis of the ongoing phase transformations of rare earth metals is made. The article emphasizes the use of correct choices to achieve a large technical and economic effect when using rare earth metals in industry. The article is intended for teachers working in the field of physics and chemistry, as well as for students of the specialty "physics and chemistry".

Micro-organisms in latex and natural rubber coagula of Hevea brasiliensis and their impact on rubber composition, structure and properties

2014 ◽  
Vol 117 (4) ◽  
pp. 921-929 ◽  
Author(s):  
M. Salomez ◽  
M. Subileau ◽  
J. Intapun ◽  
F. Bonfils ◽  
J. Sainte-Beuve ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Hevea Brasiliensis ◽  
Structure And Properties ◽  
Composition Structure ◽  
Micro Organisms

Strengthening coatings on cutting tools (analytical review of international conference literature)

2020 ◽  
pp. 234-240
Author(s):  
V.A. Levchenko ◽  
Yu.V. Panfilov
Keyword(s):  
Cutting Tools ◽  
International Standards ◽  
Structure And Properties ◽  
International Conference ◽  
Analytical Review ◽  
Composition Structure ◽  
Analytical Equipment

Tendency of strengthening coatings on cutting tools processes evolution is analyzed. Manifold of strengthening materials, strengthening coatings deposition methods, process and analytical equipment for coatings manufacture and measurement of it’s properties is described. International standards for strengthening coatings on cutting tools composition, structure and properties are presented.

Nanostructured powders based on aluminum reinforced by silicon nitride designed for spraying of multifunctional strengthened coatings

2019 ◽  
pp. 65-73
Author(s):  
T. I. Bobkova ◽  
B. V. Farmakovsky ◽  
N. A. Sokolova
Keyword(s):  
Silicon Nitride ◽  
Composite Powder ◽  
High Energy ◽  
Cold Gas Dynamic Spraying ◽  
Powder Materials ◽  
Structure And Properties ◽  
Gas Dynamic ◽  
Composition Structure ◽  
New Phase ◽  
Nanostructured Powders

The work deals with topical issues such as development of composite nanostructured powder materials. The results of creating powders based on the system “aluminum–nitride of silicon” are presented. Complex investigations of the composition, structure and properties of powder materials, as well as coatings formed on their basis by supersonic cold gas dynamic spraying, were carried out. It has been found that the high-energy treatment of a powder mixture of aluminum with nanofibers of silicon nitride provides the formation of a composite powder in which a new phase of the Si(1-х)AlхO(1-х)Nх type is formed, which additionally increases the hardness in the coatings to be sprayed.

scholarly journals Influence of Applied Bias Voltage on the Composition, Structure, and Properties of Ti:Si-Codoped a-C:H Films Prepared by Magnetron Sputtering

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Jinlong Jiang ◽  
Qiong Wang ◽  
Yubao Wang ◽  
Zhang Xia ◽  
Hua Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Magnetron Sputtering ◽  
Bias Voltage ◽  
Tribological Properties ◽  
Structure And Properties ◽  
Applied Bias ◽  
Applied Bias Voltage ◽  
Methane Mixture ◽  
Composition Structure

The titanium- and silicon-codoped a-C:H films were prepared at different applied bias voltage by magnetron sputtering TiSi target in argon and methane mixture atmosphere. The influence of the applied bias voltage on the composition, surface morphology, structure, and mechanical properties of the films was investigated by XPS, AFM, Raman, FTIR spectroscopy, and nanoindenter. The tribological properties of the films were characterized on an UMT-2MT tribometer. The results demonstrated that the film became smoother and denser with increasing the applied bias voltage up to −200 V, whereas surface roughness increased due to the enhancement of ion bombardment as the applied bias voltage further increased. The sp3carbon fraction in the films monotonously decreased with increasing the applied bias voltage. The film exhibited moderate hardness and the superior tribological properties at the applied bias voltage of −100 V. The tribological behaviors are correlated to the H/E or H3/E2ratio of the films.

4,5-Seco-4,6-cyclosteroids. I. Structure and properties of the diol from reductive rearrangement of 6β-Bromo-4β,5-epoxy-5β-cholestan-3β-ol

1969 ◽  
Vol 22 (3) ◽  
pp. 607
Author(s):  
DJ Collins ◽  
JJ Hobbs ◽  
RJ Rawson
Keyword(s):  
Physical Properties ◽  
Transformation Products ◽  
High Yield ◽  
Lithium Aluminium Hydride ◽  
Structure And Properties ◽  
Lithium Aluminium

Treatment of 6β-bromo-4β,5-epoxy-5β-cholestan-3β-ol (IV) with lithium aluminium hydride in tetrahydrofuran at reflux for 16 hr gave a high yield of a new diol, C27H48O2, formulated as 4,5-seco-4,6-cyolo-6β- cholestane-3β,5α-diol (VIIa). This assignment follows from mechanistic considerations, and the chemical and physical properties of the dial and its transformation products. ��� Stepwise removal of the oxygen functions gave the new hydrocarbon 4,5-seco-4,6-cyclo-6β-cholestane (XIXg).

Sign in / Sign up

Export Citation Format

Share Document