Protein Extraction from Heat-stabilized Defatted Rice Bran: II. The Role of Amylase, Celluclast, and Viscozyme

ABSTRACT: The effectiveness of 3 carbohydrases for protein extraction from heat-stabilized defatted rice bran (HDRB) was evaluated. Amylase, viscozyme and celluclast extracted a maximum of 45.4, 12.1, and 28.5% protein, respectively. Further study showed that extracted protein ranged from 9.5 to 58.4% under conditions of water to bran ratio (5:1 to 20:1), α-amylase (0 to 110000 units/10 g rice bran), temperature (35 to 55 °C), and time (1 to 8 h). The maximum protein extracted was 58.4% with a water to bran ratio of 17:1, 87637 units amylase, and 50.9 °C. These results suggest that impure food-grade amylase containing protease is more effective than celluclast and viscozyme in protein extraction from HDRB.     

Optimization of Lactic Acid Production by Lactobacillus delbrueckii through Response Surface Methodology

ABSTRACT: This article describes the optimization through response surface methodology of a low-cost medium based on Corn Steep Liquor (CSL) for lactic acid production by Lactobacillu delbrueckii NRRL B445. The effect of the fermentation time was also considered. A maximum lactic acid concentration (93.4 g/L) was predicted using 15 g of CSL/L and 6 g of yeast extract/L at a fermentation time of 80.1 h. However, the maximum productivity (3.50 g/L/h) was predicted by using 15 g of CSL/L, 6 g of yeast extract/L, and 8.9 g of peptone/L after 24 h. From an economical perspective, better results were obtained using 15 g of CSL/L, 6 g of yeast extract/L, and 8.9 g of peptone/L after 24 h. From an economical perspective, better results were obtained using 15 g of CSL/L alone and 24 h, achieving a maximum economical productivity of 229.7 g of lactic acid per hour and considerable savings in nutrients.     

Design and optimization of a single stage centrifugal compressor for a solar dish-Brayton system

According to the requirements of a solar dish-Brayton system,a centrifugal compressor stage with a minimum total pressure ratio of 5,an adiabatic efficiency above 75% and a surge margin more than 12% needs to be designed.A single stage,which consists of impeller,radial vaned diffuser,90° crossover and two rows of axial stators,was chosen to satisfy this system.To achieve the stage performance,an impeller with a 6:1 total pressure ratio and an adiabatic efficiency of 90% was designed and its preliminary geometry came from an in-house one-dimensional program.Radial vaned diffuser was applied downstream of the impeller.Two rows of axial stators after 90° crossover were added to guide the flow into axial direction.Since jet-wake flow,shockwave and boundary layer separation coexisted in the impeller-diffuser region,optimization on the radius ratio of radial diffuser vane inlet to impeller exit,diffuser vane inlet blade angle and number of diffuser vanes was carried out at design point.Finally,an optimized centrifugal compressor stage fulfilled the high expectations and presented proper performance.Numerical simulation showed that at design point the stage adiabatic efficiency was 79.93% and the total pressure ratio was 5.6.The surge margin was 15%.The performance map including 80%,90% and 100% design speed was also presented.     

浅谈柴油机排气道设计

本文阐述了柴油机原排气道存在的问题,然后采用CFD/CAD技术对柴油机排气道进行重新设计和优化,将设计优化好的模型制作成零件进行验证,达到了预期的效果.同时给出了某柴油机排气道优化设计的结果.     

Optimization of hybrid inoculum development techniques for biohydrogen production and preliminary scale up

Inoculum pre-treatment is a crucial aspect of hydrogen fermentation processes to establish the required microbial community for hydrogen production. This paper models and optimizes two hybrid techniques of inoculum pre-treatment for fermentative hydrogen production: ¹pH and Autoclave (PHA); ²pH and heat shock (PHS) using Response Surface Methodology (RSM). Coefficients of determination (R²) of 0.93 and 0.90 were obtained for PHA and PHS respectively and the optimized pre-treatment conditions gave hydrogen yields up to 1.35 mol H₂/mol glucose and 0.75 mol H₂/mol glucose, thus a 37.75% and 15.38% improvement on model predictions for PHA and PHS respectively.     

Optimization of conditions for hydrogen production from complex dairy wastewater by anaerobic sludge using desirability function approach

Present study deals with the multiple-response optimization for biohydrogen production using anaerobic sludge and outstanding approach to overcome the drawbacks of conventional response surface methodology (RSM). Dairy wastewater was used as source in batch fermentation was followed for this study. Response surface methodology (RSM), based on a three level, four variable Box–Behnken design, was employed to obtain the best possible combination of substrate concentration, pH, COD/N ratio and COD/P ratio for maximum H₂ yield (HY) and specific hydrogen production rate (SHPR). Experimental data were evaluated by applying RSM integrating a desirability function approach. The optimum H₂ yield and SHPR conditions were: substrate concentration 15.3 g COD/L, pH 5.5, COD/N ratio 100.5 and COD/P ratio 120 with maximum overall desirability D of 0.94. The confirmation experiment under these optimal condition showed a HY and SHPR of 13.54 mmol H₂/g COD and 29.91 mmol H₂/g-VSS.d, respectively. This was only 0.22% and 0.20%, respectively, different from the predicted values, suggesting that the desirability function approach with RSM was a useful technique to get the maximum H₂ yield and SHPR simultaneously.     

Electrochemical performance characteristics and optimum design strategies of a solid oxide electrolysis cell system for carbon dioxide reduction

An analytical model is developed to study the electrochemical characteristics of a solid oxide electrolysis cell (SOEC) for carbon dioxide reduction, in which the activation overpotential, concentration overpotential, and ohmic overpotential are considered as the main sources of voltage losses. The Bulter-Volmer equation, DGM model, and Ohm's law are employed to characterize the three overpotentials, respectively. The theoretical model is validated by comparing the simulation results with the experimental data from the literature. The anode-supported configuration SOEC is found to be the most favorable design. The effects of the cathode inlet gas molar fraction on the cathode overpotential and the cell potential are discussed in detail. It is found that there exists an optimum molar fraction for the cathode inlet gas at which the cathode concentration overpotential attains its minimum for given operation conditions. Moreover, the effects of some importantly operating parameters such as the current density, temperature and pressure on the cell potential are discussed. Thermal-electrochemical analysis shows that the Joule heat generated from the irreversibilities in the SOEC may be larger than, equal to, or smaller than the thermal energy needed for the carbon dioxide reduction reaction, and consequently, a system layout with five different design strategies to implement the carbon dioxide electrolysis is put forward.     

QP系列轨道移动式清篦破碎机的功率匹配设计

本文论述了一种新型轨道移动式清篦破碎机其传动系统的驱动电机功率的理论计算方法。对清篦破碎机的工作方式,受力情况进行了分析,提出了理论计算分工,列举实例进行了计算,并对计算结果进行分析和总结。     

地下水曝气接触氧化法除铁除锰工艺及设计应用

介绍了在进行地下水处理设计中,应根据各地区地下水不同的特点采用不同的处理方法。论述了“曝气接触氧化法”除铁除锰时,在水的不同特点下的具体方案。     

地下矿用汽车的设计原则

露天矿用汽车和地下矿用汽车虽然同为矿用自卸汽车,但由于其工作环境有天壤之别,因而两者的设计原则迥异。本文从发动机废气污染、总体结构及参数的确定,论述了两者的区别,进而阐明了地下矿用汽车的设计原则。