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Xylose: absorption, fermentation, and post-absorptive metabolism in the pig

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Journal of Animal Science and Biotechnology 2018年第1期9卷 1-9页

作者： Nichole f.Huntley John f.Patience Department of Animal Science 213 Kildee HallIowa State University Department of Animal Science 201B Kildee HallIowa State University

Xylose, as β-1,4-linked xylan, makes up much of the hemicel ulose in cel wal s of cereal carbohydrates fed to pigs. As inclusion of fibrous ingredients in swine diets continues to increase, supplementation of carbohydrases, such as xylanase,is of interest. However, much progress is warranted to achieve consistent enzyme efficacy, including an improved understanding of the utilization and energetic contribution of xylanase hydrolysis product（i.e. xylooligosaccharides or monomeric xylose）. This review examines reports on xylose absorption and metabolism in the pig and identifies gaps in this knowledge that are essential to understanding the value of carbohydrase hydrolysis products in the nutrition of the pig. Xylose research in pigs was first reported in 1954, with only sporadic contributions since. Therefore, this review also discusses relevant xylose research in other monogastric species, including humans. In both pigs and poultry, increasing purified D-xylose inclusion general y results in linear decreases in performance, efficiency, and diet digestibility. However,supplementation levels studied thus far have ranged from 5% to 40%, while theoretical xylose release due to xylanase supplementation would be less than 4%. More than 95% of ingested D-xylose disappears before the terminal ileum but mechanisms of absorption have yet to be ful y elucidated. Some data support the hypothesis that mechanisms exist to handle low xylose concentrations but become overwhelmed as luminal concentrations increase. Very little is known about xylose metabolic utilization in vertebrates but it is wel recognized that a large proportion of dietary xylose appears in the urine and significantly decreases the metabolizable energy available from the diet. Nevertheless, evidence of labeled D-xylose-1-^（14）C appearing as expired^（14）CO_2 in both humans and guinea pigs suggests that there is potential,although small, for xylose oxidation. It is yet to be determined if pigs develop increased xy

关键词： Pentose utilization Swine Threitol Xylose absorption Xylose metabolism

Implementation of a Roughness Element to Trip Transition in Large-eddy Simulation

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Journal of Thermal Science 2015年第1期24卷 30-36页

作者： J.Boudet J.-f.Monier f.Gao LMfA Ecole Centrale de Lyon Université de Lyon–UMR CNRS 5509 69134 Ecully Cedex France PhD.Candidate Université de Lyon–UMR CNRS 5509 69134 Ecully Cedex France

In aerodynamics, the laminar or turbulent regime of a boundary layer has a strong influence on friction or heat transfer. In practical applications, it is sometimes necessary to trip the transition to turbulent, and a common way is by use of a roughness element （e.g. a step） on the wall. The present paper is concerned with the numerical im- plementation of such a trip in large-eddy simulations. The study is carried out on a flat-plate boundary layer con- figuration, with Reynolds number Rex=l.3x 106. first, this work brings the opportunity to introduce a practical methodology to assess convergence in large-eddy simulations. Second, concerning the trip implementation, a volume source term is proposed and is shown to yield a smoother and faster transition than a grid step. Moreover, it is easier to implement and more adaptable. finally, two subgrid-scale models are tested： the WALE model of Nic0ud and Ducros （flow Turbul. Combust., vol. 62, 1999） and the shear-improved Smagorinsky model of Ldv^que et al. （J. fluid Mech., vol. 570, 2007）. Both models allow transition, but the former appears to yield a faster transition and a better prediction of friction in the turbulent regime.

关键词： large-eddy simulation boundary layer roughness element transition tripping

EffECT Of GAMMA RAYS IN THE PREPARATION Of POLYMER AND HYDROGEL fROM ACRYLAMIDE MONOMER

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Chinese Journal of Polymer Science 2003年第4期21卷 437-442页

作者： M.M.Alam M.f.Mina f.Akhtar NRCD INST AERE GPO Box-3787 Dhaka BangladeshNRCD INST AERE GPO Box-3787 Dhaka BangladeshNRCD INST AERE GPO Box-3787 Dhaka Bangladesh

The formation of polymer and hydrogel from aqueous solutions having 20, 30 and 40% concentrations ofacrylamide monomer by γ-ray irradiation processing in the dose range 0.06-30 kGy using a Co-60 source and theircharacterization have been observed. Polymer conversion and gel fraction are found to depend on radiation doses. Polymerconversion increases with the increase of dose, depending on the solution concentration, where maximum conversion isachieved at 0.18, 0.16 and 0.10 kGy for 20%, 30% and 40% concentrations, respectively. On the other hand, gel fractionincreases with dose from the gel point (0.12 kGy) for all concentrations, where 100% conversion of gel occurs at doses≥5 kGy. Tensile strength, viscosity and molecular weight (M_w) of polymer samples increase with both the dose and theconcentration, showing a high value of M_w up to≈10~8. Swelling of hydrogels under water with respect to time varies due tothe variation of cross-linking density formed in the gels and the maximum swelling mainly occurs within 24 h. A remarkable change of surface morphology reveals characteristic features of monomer, polymer and hydrogel films.

关键词： Polymer Hydrogel γ-Radiation Cross-linking Swelling

Catalytic combustion of soot over Ru-doped mixed oxides catalysts

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Journal of Rare Earths 2014年第7期32卷 610-620页

作者： L.f.Nascimento R.f.Martins O.A.Serra Department of Chemistry Faculdade de FilosofiaCiências e Letras de Ribeirao PretoUniversity of Sao PauloAv.Bandeirantes 3900CEP 14040-901 Ribeirao PretoSPBrazil

We employed modified substrates as outer heterogeneous catalysts to reduce the soot originating from the incomplete diesel combustion. Here, we proposed that ceria（CeO2）-based catalysts could lower the temperature at which soot combustion occurred from 610 oC to values included in the operation range of diesel exhausts（270–400 oC）. Here, we used the sol-gel method to synthesize catalysts based on mixed oxides（ZnO：CeO2） deposited on cordierite substrates, and modified by ruthenium nanoparticles. The presence of ZnO in these mixed oxides produced defects associated with oxygen vacancies, improving thermal stability, redox potential, sulfur resistance, and oxygen storage. We evaluated the morphological and structural properties of the material by X-ray diffraction（XRD）, Brumauer-emmett-teller method（BET）, temperature programmed reduction（H2-TPR）, scanning electron microscopy（SEM）, and transmission electron microscopy（TEM）. We investigated how the addition of Ru（0.5 wt.%） affected the catalytic activity of ZnO：CeO2 in terms of soot combustion. Thermogravimetric analysis（TG/DTA） revealed that presence of the catalyst decreased the soot combustion temperature by 250 oC, indicating that the oxygen species arose at low temperatures, which was the main reason for the high reactivity of the oxidation reactions. Comparative analysis of soot emission by diffuse reflectance spectroscopy（DRS） showed that the catalyst containing Ru on the mixed oxide-impregnated cordierite samples efficiently oxidized soot in a diesel stationary motor： soot emission decreased 80%.

关键词： soot combustion ceria mixed oxides ruthenium nanoparticles rare earths

AXISYMMETRIC fLOW THROUGH A PERMEABLE NEAR-SPHERE

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Applied Mathematics and Mechanics(English Edition) 2005年第10期26卷 1319-1331页

作者： f.Ayaz Department of Mathematics Faculty of Science and Arts Gazi University 06500 Teknikokullar Ankara Turkey

An analytical approach is described for the axisymmetric flow through a permeable near-sphere with a modification to boundary conditions in order to account permeability. The Stokes equation was solved by a regular perturbation technique up to the second order correction in epsilon representing the deviation from the radius of nondeformed sphere. The drag and the flow rate were calculated and the results were evaluated from the point of geometry and the permeability of the surface. An attempt also was made to apply the theory to the filter feeding problem. The filter appendages of small ecologically important aquatic organisms were modeled as axisymmetric permeable bodies, therefore a rough model for this problem was considered here as an oblate spheroid or near-sphere.

关键词： Stokes flow perturbation technique filter feeding

New Development of Acid Regeneration in Steel Pickling Plants

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Journal of Iron and Steel Research International 2008年第4期15卷 1-6页

作者： W f Kladnig ICC Chemical Consulting Vienna A-1193 Austria

for acid pickling heat treated mild steel and steel products, up to the middle of the last century, sulfuric acid was primarily in use, which has been replaced stepwise by hydrochloric acid since the sixties. During this time, the pickling of high alloyed steel with hydrofluoric acid or mixtures for hydrofluoric acid together with nitric acid has also been applied on industrial scale. The technologies used by several plant contractors hereby show considerable differences in their engineering. The study provides a survey of the progress in the state of art of regeneration technology as well as the use of different *** media in the form of a review on existing technologies as well as improvements done within the recent years in the area.

关键词： pickling mild steel high alloyed steel acid recycling technology global emission standard treatment of stack gas

Effect of thermal conductivity on heat transfer for a power-law non-Newtonian fluid over a continuous stretched surface with various injection parameters

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Applied Mathematics and Mechanics(English Edition) 2010年第8期31卷 963-968页

作者： f.A.SALAMA Department of Mathematics Faculty of Science Suez Canal University

The two-dimensional non-Newtonian steady flow on a power-law stretched surface with suction or injection is studied. Thermal conductivity is assumed to vary as a linear function of temperature. The transformed governing equations in the present study are solved numerically using the Runge-Kutta method. Through a comparison, results for a special case of the problem show excellent agreement with those in a previous work. Two cases are considered, one corresponding to a cooled surface temperature and the other to a uniform surface temperature. Numerical results show that the thermal conductivity variation parameter, the injection parameter, and the power-law index have significant influences on the temperature profiles and the Nusselt number.

关键词： non-Newtonian fluid thermal conductivity power-law fluid heat transfer

Damper placement for seismic control of super-long-span suspension bridges based on the first-order optimization method

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Science China(Technological Sciences) 2010年第7期53卷 2008-2014页

作者： Billie f SPENCER Department of Civil and Environmental Engineering University of Illinois at Urbana-Champaign

To ensure the anti-earthquake performances of super-long-span suspension bridges, effective devices should be employed to control the seismic response of key sections. In this paper, four kinds of assessment functions for seismic response control effect are formulated based on the mechanism of seismic response control with dampers and the seismic response characteristics of long-span suspension bridges. A new optimal placement method of dampers using penalty function and first-order optimization theory is then proposed. Runyang suspension bridge (RSB) with a main span of 1490 m is then taken as an example. After seismic response time-history analyses on RSB using different placements of dampers, the analysis results are optimized by employing the optimal placement method and the optimal placements of dampers with the four assessment functions are then achieved respectively. Comparison of the four optimal control effects show that different assessment functions can lead to different optimal placements when the number of dampers is certain, but all placements of dampers can reduce the seismic response of RSB significantly. The selection of assessment functions and damper optimal placement should be determined by the structural characteristics and by what is considered in the structures. Results also show that the first-order optimization is an effective method on determining the optimal placement of dampers.

关键词： suspension bridge seismic control damper placement control effect assessment first-order optimization method

Evaluation of the dust and methanol extracts of Garcinia kolae for the control of Callosobruchus maculatus (f.) and Sitophilus zeamais (Mots)

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2007年第12期8卷 912-916页

作者： OGUNLEYE R.f. ADEfEMI S.O. Department of Zoology University of Ado-Ekiti Ado Ekiti Ekiti State 234 Nigeria Department of Chemistry University of Ado-Ekiti Ado Ekiti Ekiti State 234 Nigeria

Insecticidal effects of different doses of the dust and methanol extracts of Garcinia kolae on Callosobruchus maculatus and Sitophilus zeamais were tested. The dust had no significant effect on the two insects, none of them died even at 3 d after treatment. The methanol extracts, however, had rapid lethal effects on both C. maculatus and S. zeamais. The mortality of C. maculatus by the lowest concentration of methanol extracts ranged from 95%-100% whereas in S. zeamais, the mortality ranged from 87.5%-100% and 70%-100% in concentrations of 1 g extract＋3 ml methanol and 1 g extract＋5 ml methanol, respectively, from 24 to 48 h. The least concentration of 1 g extract＋l 5 ml methanol had no significant lethal effect on Sitophilus zeamais.

关键词： Insecticidal effect Garcinia kolae Sitophilus zeamais Callosobruchus maculatus