The impact of membrane pretreatment on the enzymatic production of whey-derived galacto-oligosaccharides

2017 ◽  
Vol 41 (2) ◽  
pp. e12649 ◽  
Author(s):  
Melinda Pázmándi ◽  
Anna Maráz ◽  
Márta Ladányi ◽  
Zoltán Kovács
Keyword(s):  
Enzymatic Production ◽  
Membrane Pretreatment ◽  
The Impact

Insights into the Impact of the Nafion Membrane Pretreatment Process on Vanadium Flow Battery Performance

2016 ◽  
Vol 8 (19) ◽  
pp. 12228-12238 ◽  
Author(s):  
Bo Jiang ◽  
Lihong Yu ◽  
Lantao Wu ◽  
Di Mu ◽  
Le Liu ◽  
...  
Keyword(s):  
Nafion Membrane ◽  
Flow Battery ◽  
Membrane Pretreatment ◽  
The Impact

scholarly journals Noise propagation in metabolic pathways: the role of growth-mediated feedback

2020 ◽  
Author(s):  
A. Borri ◽  
P. Palumbo ◽  
A. Singh
Keyword(s):  
Growth Rate ◽  
Metabolic Pathways ◽  
Regulatory Networks ◽  
Metabolic Networks ◽  
Internal Noise ◽  
Cellular Growth ◽  
Enzymatic Production ◽  
External Perturbations ◽  
The Impact

AbstractMetabolic networks are known to deal with the chemical reactions responsible to fuel cellular activities with energy and carbon source and, as a matter of fact, to set the growth rate of the cell. To this end, feedback and regulatory networks play a crucial role to handle adaptation to external perturbations and internal noise. In this work, a cellular resource is assumed to be activated at the end of a metabolic pathway, by means of a cascade of transformations. Such a cascade is triggered by the catalytic action of an enzyme that promotes the first transformation. The final product is responsible for the cellular growth rate modulation. This mechanism acts in feedback at the enzymatic level, since the enzyme (as well as all species) is subject to dilution, with the dilution rate set by growth. Enzymatic production is modeled by the occurrence of noisy bursts: a Stochastic Hybrid System is exploited to model the network and to investigate how such noise propagates on growth fluctuations. A major biological finding is that, differently from other models of metabolic pathways disregarding growth-mediated feedback, fluctuations in enzyme levels do not produce only local effects, but propagate up to the final product (hence to the growth rate). Furthermore, the delay provided by the cascade length helps in reducing the impact of enzymatic noise on to growth fluctuations. Analytical results are supported by Monte Carlo simulations.

scholarly journals Microwave-Assisted Xylanase Reaction: The Impact in the Production of Prebiotic Xylooligosaccharides

2020 ◽  
Author(s):  
Hugo Mobarec ◽  
Rodrigo Villagomez ◽  
Eva Nordberg Karlsson ◽  
Javier Linares-Pastén
Keyword(s):  
Heat Transfer ◽  
Conventional Heating ◽  
Bacillus Halodurans ◽  
Molecular Dynamic Simulations ◽  
Dynamic Simulations ◽  
Enzymatic Production ◽  
Microwave Assisted ◽  
The Family ◽  
The Impact ◽  
Potential Use

The enzymatic production of prebiotic xylooligosaccharides (XOS) has become an attractive way to valorize lignocellulosic biomass. However, despite numerous xylanases reported for potential use in the production of XOS, most of the family GH10 also produce xylose. This monosaccharide can negatively affect the selectivity to stimulate the growth of intestinal microorganisms beneficial to human health. In this work, a thermostable alkali-tolerant xylanase (<i>Bh</i>Xyn10A) from <i>Bacillus halodurans</i> S7 has been used to produce XOS under conventional convective heat transfer and microwave radiation. The microwave–assisted reaction markedly decreases the xylose content in the hydrolysates and significantly increases the yield of XOS, compared to conventional heating. Molecular dynamic simulations of <i>Bh</i>Xyn10A have shown an increased fluctuation of the amino acids of the aglycone subsites suggesting that these subsites can determine the production of xylose. Thus, the microwave heating could affect the amino acid fluctuations in the aglycone subsites reducing the xylose formation. These findings open up new avenues in enzyme technology for the production of XOS.

scholarly journals Microwave-Assisted Xylanase Reaction: The Impact in the Production of Prebiotic Xylooligosaccharides

2020 ◽  
Author(s):  
Hugo Mobarec ◽  
Rodrigo Villagomez ◽  
Eva Nordberg Karlsson ◽  
Javier Linares-Pastén
Keyword(s):  
Heat Transfer ◽  
Conventional Heating ◽  
Bacillus Halodurans ◽  
Molecular Dynamic Simulations ◽  
Dynamic Simulations ◽  
Enzymatic Production ◽  
Microwave Assisted ◽  
The Family ◽  
The Impact ◽  
Potential Use

The enzymatic production of prebiotic xylooligosaccharides (XOS) has become an attractive way to valorize lignocellulosic biomass. However, despite numerous xylanases reported for potential use in the production of XOS, most of the family GH10 also produce xylose. This monosaccharide can negatively affect the selectivity to stimulate the growth of intestinal microorganisms beneficial to human health. In this work, a thermostable alkali-tolerant xylanase (<i>Bh</i>Xyn10A) from <i>Bacillus halodurans</i> S7 has been used to produce XOS under conventional convective heat transfer and microwave radiation. The microwave–assisted reaction markedly decreases the xylose content in the hydrolysates and significantly increases the yield of XOS, compared to conventional heating. Molecular dynamic simulations of <i>Bh</i>Xyn10A have shown an increased fluctuation of the amino acids of the aglycone subsites suggesting that these subsites can determine the production of xylose. Thus, the microwave heating could affect the amino acid fluctuations in the aglycone subsites reducing the xylose formation. These findings open up new avenues in enzyme technology for the production of XOS.

Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

1962 ◽  
Vol 14 ◽  
pp. 415-418
Author(s):  
K. P. Stanyukovich ◽  
V. A. Bronshten
Keyword(s):  
Explosive Charge ◽  
The Moon ◽  
Meteorite Impacts ◽  
The Earth ◽  
Lunar Craters ◽  
The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

The Geosciences Applied to Lunar Exploration

1962 ◽  
Vol 14 ◽  
pp. 169-257 ◽  
Author(s):  
J. Green
Keyword(s):  
Lunar Surface ◽  
Probable Mechanism ◽  
Point Of View ◽  
Lunar Exploration ◽  
Geological Model ◽  
Apply Geophysics ◽  
Surface Features ◽  
The Impact

The term geo-sciences has been used here to include the disciplines geology, geophysics and geochemistry. However, in order to apply geophysics and geochemistry effectively one must begin with a geological model. Therefore, the science of geology should be used as the basis for lunar exploration. From an astronomical point of view, a lunar terrain heavily impacted with meteors appears the more reasonable; although from a geological standpoint, volcanism seems the more probable mechanism. A surface liberally marked with volcanic features has been advocated by such geologists as Bülow, Dana, Suess, von Wolff, Shaler, Spurr, and Kuno. In this paper, both the impact and volcanic hypotheses are considered in the application of the geo-sciences to manned lunar exploration. However, more emphasis is placed on the volcanic, or more correctly the defluidization, hypothesis to account for lunar surface features.

Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

1997 ◽  
Vol 161 ◽  
pp. 197-201 ◽  
Author(s):  
Duncan Steel
Keyword(s):  
Probability Distributions ◽  
Regions Of Interest ◽  
Significant Fraction ◽  
Organic Chemicals ◽  
Impact Speed ◽  
The Mean ◽  
The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

Organic Syntheses During the Impact of a Comet with a Gaseous Planet

1997 ◽  
Vol 161 ◽  
pp. 189-195
Author(s):  
Cesare Guaita ◽  
Roberto Crippa ◽  
Federico Manzini
Keyword(s):  
Polymeric Material ◽  
Molecular Form ◽  
Parent Compound ◽  
Blue Filter ◽  
Organic Syntheses ◽  
The Impact

AbstractA large amount of CO has been detected above many SL9/Jupiter impacts. This gas was never detected before the collision. So, in our opinion, CO was released from a parent compound during the collision. We identify this compound as POM (polyoxymethylene), a formaldehyde (HCHO) polymer that, when suddenly heated, reformes monomeric HCHO. At temperatures higher than 1200°K HCHO cannot exist in molecular form and the most probable result of its decomposition is the formation of CO. At lower temperatures, HCHO can react with NH3 and/or HCN to form high UV-absorbing polymeric material. In our opinion, this kind of material has also to be taken in to account to explain the complex evolution of some SL9 impacts that we observed in CCD images taken with a blue filter.

Hydrogen Cyanide Polymers from the Impact of Comet P/Shoemaker-Levy 9 on Jupiter

1997 ◽  
Vol 161 ◽  
pp. 179-187
Author(s):  
Clifford N. Matthews ◽  
Rose A. Pesce-Rodriguez ◽  
Shirley A. Liebman
Keyword(s):  
Amino Acids ◽  
Solar System ◽  
Hydrogen Cyanide ◽  
Nitrogen Heterocycles ◽  
Laboratory Studies ◽  
Heterogeneous Solids ◽  
The Many ◽  
Comet Halley ◽  
The Impact ◽  
By Products

AbstractHydrogen cyanide polymers – heterogeneous solids ranging in color from yellow to orange to brown to black – may be among the organic macromolecules most readily formed within the Solar System. The non-volatile black crust of comet Halley, for example, as well as the extensive orangebrown streaks in the atmosphere of Jupiter, might consist largely of such polymers synthesized from HCN formed by photolysis of methane and ammonia, the color observed depending on the concentration of HCN involved. Laboratory studies of these ubiquitous compounds point to the presence of polyamidine structures synthesized directly from hydrogen cyanide. These would be converted by water to polypeptides which can be further hydrolyzed to α-amino acids. Black polymers and multimers with conjugated ladder structures derived from HCN could also be formed and might well be the source of the many nitrogen heterocycles, adenine included, observed after pyrolysis. The dark brown color arising from the impacts of comet P/Shoemaker-Levy 9 on Jupiter might therefore be mainly caused by the presence of HCN polymers, whether originally present, deposited by the impactor or synthesized directly from HCN. Spectroscopic detection of these predicted macromolecules and their hydrolytic and pyrolytic by-products would strengthen significantly the hypothesis that cyanide polymerization is a preferred pathway for prebiotic and extraterrestrial chemistry.

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