Search

Injection molding technology is known as the most widely used method in mass production of plastic products. To meet the quality requirements, a lot of methods were applied in optimization of injection molding process parameter. In this study the optimization based on Taguchi orthogonal array and Grey relational analysis (GRA) is used to optimize the injection molding process parameters on a LED lens. The four process parameters are: packing pressure, injection speed, melt temperature and mold temperature. The multiresponse quality characteristics are total displacement, volumetric shrinkage, and thermal residual stress. The optimal molding parameters are packing pressure (90 MPa), injection speed (300 mm/sec), melt temperature (270 °C) and mold temperature (90 °C). The luminous uniformity of the LED is 92.61 % and the viewing angle of the LED is 124.76°. Among the four factors, packing pressure plays the key role in reducing total displacement, volumetric shrinkage, and thermal residual stress. [ABSTRACT FROM AUTHOR]

An extracellular antifungal chitinase from L. lecanii strain 43H was purified by ammonium sulfate precipitation and DEAE- Sephadex A-50 ion exchange chromatography; it showed a molecular mass of approximately 33 kDa with a specific activity of 167.5 U/mg protein and purification factor of 2.5. Optimum temperature and pH were observed at 40 °C and pH 6.0, respectively. This enzyme was stable at up to 40 °C and at pH 5.0-6.0. The kinetic constants Km and Vmax determined for the chitinase with colloidal chitin as substrate was 0.82 mg/mL and 4.51 U/mg, respectively. The presence of 5-15 mM tested metal ions led to activation of the chitinase activity with an increase of up to 126% except for Al3+, Ag+, and Hg2+. Tween 80 (0.5%), Tween 20 (1%-2%), and Triton X-100 (1%) increased the enzyme activity by up to 25%, whereas higher concentration of 2% SDS completely inhibited the enzyme. The chitinase exhibited high resistance to organic solvents (methanol, acetone) and retained 89%-95% of its initial activity. The chitinase was found to inhibit the conidial germination and mycelial growth of plant pathogenic fungi. These results suggest that chitinase might be used in enzymatic reactions and as a potential fungicide against pathogens. [ABSTRACT FROM AUTHOR]

Spores of Aspergillus sp. SU14 were treated repeatedly and sequentially with Co60 γ-rays, ultraviolet irradiation, and Nmethyl- N'-nitro-N-nitrosoguanidine. One selected mutant strain, Aspergillus sp. SU14-M15, produced cellulase in a yield 2.2- fold exceeding that of the wild type. Optimal conditions for the production of cellulase by the mutant fungal strain using solid-state fermentation were examined. The medium consisted of wheat-bran supplemented with 1% (w/w) urea or NH4Cl, 1% (w/w) rice starch, 2.5mM MgCl2, and 0.05% (v/w) Tween 80. Optimal moisture content and initial pH was 50% (v/w) and 3.5, respectively, and optimal aeration area was 3/100 (inoculated wheat bran/container). The medium was inoculated with 25% 48 hr seeding culture and fermented at 35°C for 3 days. The resulting cellulase yield was 8.5-fold more than that of the wild type strain grown on the basal wheat bran medium. [ABSTRACT FROM AUTHOR]