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  • 1
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 141-143 (July 2008), p. 451-456 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: The effect of processing parameters on the semi-solid microstructure has beeninvestigated in the course of semi-solid slurry preparation of A356 Al alloy by ultrasonic vibrationmethod. The A356 melt in temperature of 630660°C was poured into a special metal cup, andexposed to ultrasonic vibration at 20 kHz or isothermal holding for a certain time after vibration.The results show that the semi-solid slurry with primary α-Al crystals smaller than 90 μm and anaverage shape coefficient F S (SF was defined as SF4 A/L2P) above 0.5 could be prepared byultrasonic vibration for a time less than 144 s. In the isothermal holding period after a short time ofultrasonic vibration, the average particle diameter increased with the increase of holding time, butF S decreased at first, and then increased a little. It was discovered that ultrasonic vibration is a goodmethod to prepare semi-solid slurry with fine and relatively round primary crystals due to cavitationand acoustic streaming effects
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 141-143 (July 2008), p. 767-771 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: The preparation of semi-solid slurry of hypereutectic Al-Si alloy by Ultrasonic Vibration(USV) has been studied. The A390 alloy melt was poured into a preheated metal cup, andsubsequently the ultrasonic vibrator was dipped into the melt and USV was imposed. The solidifiedmicrostructure of the slurry has been analyzed, and the mechanical properties of the alloy have beentested by making samples through diecasting of the slurry. The results show that the primary Siparticles of A390 alloy became finer, rounder and uniformly distributed in microstructure of A390alloy slurry if imposed with USV, and average diameter of primary Si particles was about 20μm. WithUSV, the ultimate tensile strength and the hardness of rheo-casted samples increased by over 25% andnear 50% respectively besides the elongation rose by above 100%. After heat treatment, themechanical properties were further improved. In addition, the mechanism of preparation of semi-solidslurry of hypereutectic Al-Si alloy by USV is discussed
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica solida Sinica 4 (1991), S. 39-47 
    ISSN: 0894-9166
    Keywords: singular integral ; boundary element method ; isoparametric element ; finite part of singular integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A numerical method for the Cauchy principal value of the singular integral in BEM is developed using the concept of finite part integration under integral variable transformation. It is applied to the numerical integration on isoparametric element successfully, as shown in the examples in this paper.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Munksgaard International Publishers
    Physiologia plantarum 123 (2005), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effects of silicon application on the drought tolerance of sorghum (Sorghum bicolor (L.) Moench) were investigated for two cultivars differing in drought susceptibility. Silicon application ameliorated the decrease in dry weight under drought stress conditions, but had no effect on dry matter production under wet conditions. Under dry conditions, silicon-applied sorghum had a lower shoot to root (S/R) ratio, indicating the facilitation of root growth and the maintenance of the photosynthetic rate and stomatal conductance at a higher level compared with plants grown without silicon application. The diurnal determination of the transpiration rate indicated that the silicon-applied sorghum could extract a larger amount of water from drier soil and maintain a higher stomatal conductance. Very similar effects of silicon application were observed for both cultivars regardless of their drought susceptibility. These results suggest that silicon application may be useful to improve the drought tolerance of sorghum via the enhancement of water uptake ability.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1365-4632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background  Vitiligo is an acquired depigmentary disorder of the skin and hair which results from selective destruction of melanocytes. Serological typing and genotyping of human leukocyte antigen (HLA) have shown discrepancies in HLA associations with vitiligo in different ethnic populations.Methods  Polymerase chain reaction sequence-specific primer (PCR-SSP) method was used to analyze the distribution of HLA-DQA1 and -DQB1 alleles among 187 patients with vitiligo and 273 healthy controls through Epi Info version 6 package (Centers for Disease Control and Prevention, Atlanta, GA, USA).Results  The frequencies of HLA-DQA1*0302 (OR = 1.98, Pc 〈 0.01), -DQB1*0303 (OR = 3.14, Pc 〈 0.001), and -DQB1*0503 (OR = 3.36, Pc 〈 0.05) alleles were significantly increased in patients with vitiligo compared with controls, and HLA-DQA1*0501 (OR = 0.40, Pc 〈 0.01) allele frequency was highly decreased. HLA-DQA1*0302 (OR = 5.19, Pc 〈 0.001), -DQA1*0601 (OR = 2.95, Pc 〈 0.05), -DQB1*0303 (OR = 4.50, Pc 〈 0.001), and -DQB1*0503 (OR = 6.69, Pc 〈 0.001) alleles were positively associated, whereas HLA-DQA1*0501 (OR = 0.05, Pc 〈 0.001) allele was negatively associated with childhood vitiligo patients, and HLA-DQB1*0303 (OR = 2.76, Pc 〈 0.001) allele was positively associated with adult vitiligo patients compared with controls. The frequency of HLA-DQB1*0303 (OR = 3.72, Pc 〈 0.001) allele was significantly increased in localized vitiligo patients vs. controls, whereas HLA-DQA1*0302 (OR = 2.47, Pc 〈 0.01), -DQB1*0303 (OR = 2.67, Pc 〈 0.01), and -DQB1*0503 (OR = 4.46, Pc 〈 0.01) allele frequencies were significantly increased and -DQA1*0501 (OR = 0.27, Pc 〈 0.01) allele frequency was highly decreased in generalized vitiligo patients.Conclusions  HLA-DQA1*0302, -DQA1*0601, -DQB1*0303, and -DQB1*0503 alleles could be susceptible alleles of vitiligo, while HLA-DQA1*0501 allele could be a protective allele in Chinese Hans. There may be different genetic backgrounds between vitiligo patients of childhood and adult, localized and generalized.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 35 (1991), S. 1-3 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Ethanol is identified as a strongly inhibitory metabolite in addition to acetic acid and 2,3-butanediol in 2,3-butanediol production by Enterobacter aerogenes. A model is proposed to describe the multiproduct-inhibited growth of E. aerogenes in 2,3-butanediol fermentation. The model is verified with data from anaerobic and microaerobic continuous culture. On the basis of this model the difference in biomass production and product patterns during anaerobic and microaerobic growth of E. aerogenes is discussed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 33 (1990), S. 485-489 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The effect of pH and acetic acid on growth and 2,3-butanediol production of Enterobacter aerogenes from glucose was investigated in a microaerobic continuous culture. At a dilution rate of 0.20 h−1 and a fixed oxygen uptake rate (OUR) of 31.5 mmol l−1 h−1 the biomass concentration increased with pH ranging from 5.0 to 7.0, while the specific ATP requirement of the cells decreased. In the pH range 5.5–6.5 the product concentration (butanediol + acetoin) was maximal and nearly constant. However, the specific production continuously declined with increasing pH. Experiments with addition of acetic acid showed that the various effects of pH are due to inhibition of the by-product acetic acid on cell growth. The strength of the acetic and inhibition depended only on the concentration of its undissociated form [HAc]. The biomass concentration and the specific OUR were also only functions of [HAc], irrespective of the pH. Although the specific ATP requirement (q ATP) strongly depended on the pH, [HAc] at constant pH.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 33 (1990), S. 264-268 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The influence of oxygen on growth and production of 2,3-butanediol and acetoin by Enterobacter aerogenes was studied in continuous culture. At all dilution rates (D) studied cell mass increased steadily with increasing oxygen uptake rate (OUR), hence the micro-aerobic cultivation was energy-limited. The biomass yield on oxygen increased with D which suggests that cells need more energy for maintenance functions at lower D. At each D an optimal OUR giving highest volumetric productivity for the sum of butanediol and acetoin was found. The optimal OUR increased with D. The occurrence of optimal OURs results from the various effects of O2 on growth and specific productivity. The latter was found to be a linear function of the specific OUR irrespective of D. At optimal OUR the cells proved to have equal specific OURs and equal specific productivities representing a fixed relationship between fermentative and respiratory metabolism. The product yield based on glucose and corrected for biomass formation was 80%. A product concentration as high as 43 g/l was obtained at D =0.1 h−1 while the volumetric productivity was the highest at D =0.28 h−1 (5.6 g/l and hour). The findings further indicate that growth and product generation are obviously non-associated phenomena. Hence, high productivities may be achievable by cell recycling and cell immobilisation systems.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The influence of interdiffusion on eigenstates in an interdiffusion-induced GaAs/AlxGa1-xAs single-quantum-well structure is analysed numerically by the finite element method. In this approach, the confinement potential profile of the interdiffused quantum well structure is nonlinear and is modelled by an error function and, in particular, the nature of the effective mass of an electron is considered. The results show that the number of eigenstates and energy levels varies with the extent of the interdiffusion. Numerical results for the quasi-bound states in the quantum well structure with an applied electric field are also presented.
    Type of Medium: Electronic Resource
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