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31.
An experimental and numerical study have been carried out to investigate the distribution of radial local heat transfer coefficients of impinging submerged circular jets. Good agreement is achieved between the experimental results and the predicted value. Results show that the outer peak usually occurs at the radial location of r/d= 1.8~2.0, in which transition from laminar to turbulence happens resulting from disappeared pressure gradient abruptly, and that the inner peak appears rigidly at r/d=0.5, where the boundary layer has a minimum thickness because of elevating pressure gradient. 相似文献
32.
Low molecular weight aldehydes were formed during surface water preozonization, their levels showing a positive correlation with increasing ozone dose applied and with increasing water temperature. A strong negative correlation was observed between aldehyde levels and U.V. absorbance at 254 nm.Coagulation had no influence on the aldehydes present and the influence of rapid double layer filtration varied strongly with temperature : significant removals were only observed above 10°C.Mutagenic activity generated by preozonization in Salmonella typhimurium TA98 shows an ozone dose depending relationship different from the formation of linear aldehydes. Its removal by coagulation is not effective but rapid double layer filtration reduces mutagenic activity to marginal levels.In this respect too no clear parallel can be drawn between the presence of low molecular weight aldehydes and mutagenic activity. 相似文献
33.
Larissa Canilha Walter Carvalho Marco Giulietti Maria Das Graças Almeida Felipe João Batista Almeida E Silva 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(5):715-721
BACKGROUND: Xylitol bioproduction from lignocellulosic residues comprises hydrolysis of the hemicellulose, detoxification of the hydrolysate, bioconversion of the xylose, and recovery of xylitol from the fermented hydrolysate. There are relatively few reports on xylitol recovery from fermented media. In the present study, ion‐exchange resins were used to clarify a fermented wheat straw hemicellulosic hydrolysate, which was then vacuum‐concentrated and submitted to cooling in the presence of ethanol for xylitol crystallization. RESULTS: Sequential adsorption into two anion‐exchange resins (A‐860S and A‐500PS) promoted considerable reductions in the content of soluble by‐products (up to 97.5%) and in medium coloration (99.5%). Vacuum concentration led to a dark‐colored viscous solution that inhibited xylitol crystallization. This inhibition could be overcome by mixing the concentrated medium with a commercial xylitol solution. Such a strategy led to xylitol crystals with up to 95.9% purity. The crystallization yield (43.5%) was close to that observed when using commercial xylitol solution (51.4%). CONCLUSION: The experimental data demonstrate the feasibility of using ion‐exchange resins followed by cooling in the presence of ethanol as a strategy to promote the fast recovery and purification of xylitol from hemicellulose‐derived fermentation media. Copyright © 2008 Society of Chemical Industry 相似文献
34.
Norris Fran H.; Murphy Arthur D.; Baker Charlene K.; Perilla Julia L.; Rodriguez Francisco Gutiérrez; Rodriguez José de Jesús Gutiérrez 《Canadian Metallurgical Quarterly》2003,112(4):646
Prevalence rates of trauma and posttraumatic stress disorder (PTSD) were estimated from a probability sample of 2,509 adults from 4 cities in Mexico. PTSD was assessed according to Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 1994) criteria using the Composite International Diagnostic Interview (CIDI; WHO, 1997). Lifetime prevalence of exposure and PTSD were 76% and 11.2%, respectively. Risk for PTSD was highest in Oaxaca (the poorest city), persons of lower socioeconomic status, and women. Conditional risk for PTSD was highest following sexual violence, but nonsexual violence and traumatic bereavement had greater overall impact because of their frequency. Of lifetime cases, 62% became chronic; only 42% received medical or professional care. The research demonstrates the importance of expanding the epidemiologic research base on trauma to include developing countries around the world. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
35.
Mamiko Hori Cécile Pagnoux Jean-François Baumard Masayuki Nogami 《Journal of Materials Science》2007,42(1):80-86
A new method is proposed to produce gold nanoparticles (GNP) by in situ reduction of a gold salt dissolved in water. The reducing
agent used is Tiron instead of the citrate anion most often mentioned in literature. The influence of various parameters has
been investigated, such as the content of Tiron with respect to that of the precursor of gold HAuCl4, or the initial pH of the solution after mixing of reactants. It is shown that Tiron also exerts a positive influence as
a dispersant, which impedes agglomeration of gold nanoparticles. The typical average size of GNP synthesized in the present
work is close to 7 nm. 相似文献
36.
Hadjem A. Lautru D. Dale C. Man Fai Wong Hanna V.F. Wiart J. 《Microwave Theory and Techniques》2005,53(1):4-11
This paper gives a first comparison of specific absorption rate (SAR) induced in a child-sized (CS) head and an adult head using a dual-band mobile phone. In the second study, the visible human head is considered and comparison of SAR induced in a CS or child-like (CL) head and an adult head using a dual-band mobile phone is given. All the peaks of average SAR over a mass of 10 and 1 g in the head and the power budget are determined in the two comparisons using the finite-difference time-domain method. The differences between the results for adult and CS or CL heads are given at 900 and 1800 MHz. No important differences are noted for the peak SAR averaged over 10 g (SAR10 g), between the two adult head models, as well as between the two child head models. The peak SAR10 g in the brain of the CS or CL head is slightly more significant than that for the adult one. 相似文献
37.
Ho Nam Kwon Man Geun Kim Il-Han Hwang Young Kab Yun Seon-Ju Kim Jong-Hyun Lee 《Photonics Technology Letters, IEEE》2005,17(4):774-776
We developed a micromachined X-type 2/spl times/4 optical add-drop module (OADM) featuring no difference in propagation length. Four pairs of lensed fibers are aligned in "X" position, and four micromirrors are located between the pairs of optical fibers. The OADM was fabricated utilizing a silicon-on-insulator process. Electrostatic comb actuators can be driven up to 90 /spl mu/m to change the light path within 1 ms. The insertion loss and the on-off ratio were less than 3 and 70 dB, respectively. The loss uniformity in every channel was 1.5 dB. 相似文献
38.
Physically based simulation of human hair is a well studied and well known problem. But the “pure” physically based representation of hair (and other animation elements) is not the only concern of the animators, who want to “control” the creation and animation phases of the content. This paper describes a sketch-based tool, with which a user can both create hair models with different styling parameters and produce animations of these created hair models using physically and key frame-based techniques. The model creation and animation production tasks are all performed with direct manipulation techniques in real-time. 相似文献
39.
A. A. Man’kov Yu. V. Krasovitskii E. V. Arkhangel’skaya S. L. Kabargin D. B. Troshchenko N. N. Lobacheva V. P. Dobrosotskii 《Refractories and Industrial Ceramics》2008,49(3):225-228
Methods are proposed for designing interpolation models for the preliminary determination and subsequent forecasting of general
and fractional breakthrough coefficients for dust used with granular filters, as employed in energy-saving and high-performance
dust trapping from technological gases and ventilation discharges in refractory production. The models are supplied with nomograms,
which makes them widely suitable for experts working in environmental protection at refractory-producing organizations. The
main factors are identified that influence the performance. The results are of interest to experts in related areas of industry
such as building materials and engineering ceramics and so on.
Translated from Novye Ogneupory, No. 4, pp. 64–67, April, 2008. 相似文献
40.
Ezequiel R. Soulé Guillermo E. Eliçabe Roberto J. J. Williams 《Polymer Bulletin》2008,60(2-3):417-423
An unexpected experimental finding is reported where the primary morphology developed during polymerization-induced
phase separation in a rubber-modified thermoplastic practically disappears at high conversions. This process
was evidenced by light scattering (LS) and scanning electron microscopy (SEM) for a particular composition
of solutions of polyisobutylene oligomers (PIB) in isobornylmethacrylate (IBoMA), during the free-radical
polymerization of the monomer. The primary phase separation produced a dispersion of domains rich in PIB
containing significant amounts of the monomer (IBoMA). Polymerization of the monomer in these domains occurred
at high overall conversions producing the filling of dispersed domains with a PIBoMA-PIB blend that could
not be distinguished from the matrix. Under these conditions the final material had the appearance of a
homogeneous blend. 相似文献