scholarly journals Kinetics of amino sugar formation from organic residues of different quality

2013 ◽  
Vol 57 ◽  
pp. 814-821 ◽  
Author(s):  
Zhen Bai ◽  
Samuel Bodé ◽  
Dries Huygens ◽  
Xudong Zhang ◽  
Pascal Boeckx
Keyword(s):  
Amino Sugar ◽  
Organic Residues ◽  
Kinetics Of

Epimerization of lactose to free lactulose in heated model milk solutions

1985 ◽  
Vol 52 (3) ◽  
pp. 409-417 ◽  
Author(s):  
Barry D. Greig ◽  
Gerald A. Payne
Keyword(s):  
Thermal Effects ◽  
Amino Sugar ◽  
The Other ◽  
Processing Conditions ◽  
Amino Groups ◽  
First Order ◽  
Base Catalysts ◽  
The Difference ◽  
Kinetics Of

SUMMARYThe kinetics of the epimerization of lactose to lactulose were determined for two ‘model milk’ solutions, one containing lactose and the other lactose and lysine. The lysine was added to lactose to determine whether amino groups of proteins act as base catalysts promoting the production of free lactulose. The presence of lysine actually reduced the rate of production of free lactulose, presumably by the formation of amino-sugar complexes. The rate of production of free lactulose over the range of processing conditions was shown to be first order for both systems. Thermal effects on lactose were shown to be complex. The epimerization of lactose to lactulose was reversible and both sugars were thermally decomposed to their monosaccharides. The difference in the rate of production of free lactulose between the lactose, and the lactose and lysine solutions was also observed in processed milk and its ultrafiltrate (protein free).

Amino sugar phosphate levels in Giardia change during cyst wall formation

Microbiology ◽  
2004 ◽  
Vol 150 (5) ◽  
pp. 1225-1230 ◽  
Author(s):  
Keriman Sener ◽  
Zuojun Shen ◽  
David S. Newburg ◽  
Edward L. Jarroll
Keyword(s):  
Cyst Wall ◽  
Amino Sugar ◽  
Giardia Intestinalis ◽  
Sugar Phosphate ◽  
Pronounced Increase ◽  
Human Small Intestine ◽  
Cyst Viability ◽  
Novel Method ◽  
Sugar Phosphates ◽  
Kinetics Of

The parasite Giardia intestinalis exists as a trophozoite (vegetative) that infects the human small intestine, and a cyst (infective) that is shed in host faeces. Cyst viability in the environment depends upon a protective cyst wall, which consists of proteins and a unique β(1-3) GalNAc homopolymer. UDP-GalNAc, the precursor for this polysaccharide, is synthesized from glucose by an enzyme pathway that involves amino sugar phosphate intermediates. Using a novel method of microanalysis by capillary electrophoresis, the levels of amino sugar phosphate intermediates in trophozoites before encystment, during a period of active encystment and after the peak of encystment were measured. These levels were used to deduce metabolic control of amino sugar phosphates associated with encystment. Levels of amino sugar phosphate intermediates increased during encystment, and then decreased to nearly non-encysting levels. The most pronounced increase was in glucosamine 6-phosphate, which is the first substrate unique in this pathway, and which is the positive effector for the pathway's putative rate-controlling enzyme, UDP-GlcNAc pyrophosphorylase. Moreover, more UDP-GalNAc than UDP-GlcNAc, its direct precursor, was detected at 24 h. It is postulated that the enhanced UDP-GalNAc is a result of enhanced synthesis of UDP-GlcNAc by the pyrophosphorylase, and its preferential conversion to UDP-GalNAc. These results suggest that kinetics of amino sugar phosphate synthesis in encysting Giardia favours the direction that supports cyst wall synthesis. The enzymes involved in synthesis of UDP-GalNAc and its conversion to cyst wall might be potential targets for therapeutic inhibitors of Giardia infection.

Direct observations of radiation-enhanced transformations in glass

1983 ◽  
Vol 41 ◽  
pp. 354-355
Author(s):  
J. F. DeNatale ◽  
D. G. Howitt
Keyword(s):  
Glass Matrix ◽  
Diffusion Mechanism ◽  
Bubble Formation ◽  
Silicate Glasses ◽  
Phase Decomposition ◽  
Direct Observations ◽  
Thin Foils ◽  
Oxygen Bubble ◽  
Electron Energy Loss ◽  
Kinetics Of

The electron irradiation of silicate glasses containing metal cations produces various types of phase separation and decomposition which includes oxygen bubble formation at intermediate temperatures figure I. The kinetics of bubble formation are too rapid to be accounted for by oxygen diffusion but the behavior is consistent with a cation diffusion mechanism if the amount of oxygen in the bubble is not significantly different from that in the same volume of silicate glass. The formation of oxygen bubbles is often accompanied by precipitation of crystalline phases and/or amorphous phase decomposition in the regions between the bubbles and the detection of differences in oxygen concentration between the bubble and matrix by electron energy loss spectroscopy cannot be discerned (figure 2) even when the bubble occupies the majority of the foil depth.The oxygen bubbles are stable, even in the thin foils, months after irradiation and if van der Waals behavior of the interior gas is assumed an oxygen pressure of about 4000 atmospheres must be sustained for a 100 bubble if the surface tension with the glass matrix is to balance against it at intermediate temperatures.

Irradiation behavior of pyrolytic silicon carbide

1983 ◽  
Vol 41 ◽  
pp. 72-73
Author(s):  
R. J. Lauf
Keyword(s):  
Silicon Carbide ◽  
Fission Products ◽  
Thermodynamics And Kinetics ◽  
Neutron Fluences ◽  
Fuel Particles ◽  
Sic Coatings ◽  
Irradiation Behavior ◽  
Kinetics Of ◽  
Htgr Fuel

Fuel particles for the High-Temperature Gas-Cooled Reactor (HTGR) contain a layer of pyrolytic silicon carbide to act as a miniature pressure vessel and primary fission product barrier. Optimization of the SiC with respect to fuel performance involves four areas of study: (a) characterization of as-deposited SiC coatings; (b) thermodynamics and kinetics of chemical reactions between SiC and fission products; (c) irradiation behavior of SiC in the absence of fission products; and (d) combined effects of irradiation and fission products. This paper reports the behavior of SiC deposited on inert microspheres and irradiated to fast neutron fluences typical of HTGR fuel at end-of-life.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

Ion Beam Induced Interfacial Reactions in Molybdenum Thin Films on Silicon

1981 ◽  
Vol 39 ◽  
pp. 162-163
Author(s):  
L. J. Chen ◽  
L. S. Hung ◽  
J. W. Mayer
Keyword(s):  
Ion Beam ◽  
Chemical Vapor ◽  
Interfacial Reactions ◽  
Practical Applications ◽  
Microelectronic Devices ◽  
Recent Emergence ◽  
Chemical Vapor Deposited ◽  
Atomic Mixing ◽  
Silicon Interface ◽  
Kinetics Of

When an energetic ion penetrates through an interface between a thin film (of species A) and a substrate (of species B), ion induced atomic mixing may result in an intermixed region (which contains A and B) near the interface. Most ion beam mixing experiments have been directed toward metal-silicon systems, silicide phases are generally obtained, and they are the same as those formed by thermal treatment.Recent emergence of silicide compound as contact material in silicon microelectronic devices is mainly due to the superiority of the silicide-silicon interface in terms of uniformity and thermal stability. It is of great interest to understand the kinetics of the interfacial reactions to provide insights into the nature of ion beam-solid interactions as well as to explore its practical applications in device technology.About 500 Å thick molybdenum was chemical vapor deposited in hydrogen ambient on (001) n-type silicon wafer with substrate temperature maintained at 650-700°C. Samples were supplied by D. M. Brown of General Electric Research & Development Laboratory, Schenectady, NY.

In situ study of electron beam-induced chemical vapor deposition of Au in an environmental TEM

1995 ◽  
Vol 53 ◽  
pp. 256-257
Author(s):  
J. Drucker ◽  
R. Sharma ◽  
J. Kouvetakis ◽  
K.H.J. Weiss
Keyword(s):  
Electron Beam ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Quantum Effect ◽  
Line Drawing ◽  
Chemical Vapor ◽  
Environmental Cell ◽  
Engineering Changes ◽  
Kinetics Of

Patterning of metals is a key element in the fabrication of integrated microelectronics. For circuit repair and engineering changes constructive lithography, writing techniques, based on electron, ion or photon beam-induced decomposition of precursor molecule and its deposition on top of a structure have gained wide acceptance Recently, scanning probe techniques have been used for line drawing and wire growth of W on a silicon substrate for quantum effect devices. The kinetics of electron beam induced W deposition from WF6 gas has been studied by adsorbing the gas on SiO2 surface and measuring the growth in a TEM for various exposure times. Our environmental cell allows us to control not only electron exposure time but also the gas pressure flow and the temperature. We have studied the growth kinetics of Au Chemical vapor deposition (CVD), in situ, at different temperatures with/without the electron beam on highly clean Si surfaces in an environmental cell fitted inside a TEM column.

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