Fermentation optimization for the production of lovastatin by Aspergillus terreus: use of response surface methodology

A Box–Behnken experimental design was used to investigate the effects of five factors—ie oxygen content in the gas phase; concentrations of C, N and P; and fermentation time—on the concentrations of biomass and lovastatin produced in batch cultures of Aspergillus terreus. The values of the various factors in the experiment ranged widely, as follows: 20–80% (v/v) oxygen in the aeration gas; 8–48 g dm^?3 C‐concentration; 0.2–0.6 g dm^?3 N‐concentration; 0.5–2.5 g dm^?3 phosphate‐concentration; and 7–11 days fermentation time. No previous work has used statistical analysis in documenting the interactions between oxygen supply and nutrient concentrations in lovastatin production. The Box–Behnken design identified the oxygen content in the gas phase as the principal factor influencing the production of lovastatin. Both a limitation and excess of oxygen reduced lovastatin titers. A medium containing 48 g dm^?3 C supplied as lactose, 0.46 g dm^?3 N supplied as soybean meal, and 0.79 g dm^?3 phosphate supplied as KH₂PO₄, was shown to support high titers (～230 mg dm^?3) of lovastatin in a 7‐day fermentation in oxygen‐rich conditions (80% v/v oxygen in the aeration gas). Under these conditions, the culture medium had excess carbon but limiting amounts of nitrogen. The optimized fermentation conditions raised the lovastatin titer by four‐fold compared with the worst‐case scenario within the range of factors investigated. Copyright © 2004 Society of Chemical Industry     

响应面法优化达托霉素发酵培养基

采用响应面法对玫瑰孢链霉菌发酵产达托霉素的培养基进行了优化。首先通过Placket-Burman设计法筛选出影响达托霉素产量的4个重要因素:初始pH值、葡萄糖、L-天冬氨酸(L-Asp)、硫酸钾。其中初始pH值的影响极为显著(p<0.01),因此,对初始pH值进行了单因素试验,得到最优初始pH值为8.6。在此基础上对其余3个因素用最陡爬坡路径逼近最大响应区域后,利用响应面中心组合设计对显著因素进行优化,得到最适培养基组成为:葡萄糖13.0 g/L、L-Asp 2.6 g/L、硫酸钾4.1 g/L。在此优化条件下,达托霉素产量达373.98 mg/L,与预测值(365.76 mg/L)非常接近,比优化前产量提高了2.25倍。     

The effect of secondary nanofiller on mechanical properties and formulation optimization of HDPE/nanoclay/nanoCaCO3 hybrid nanocomposites using response surface methodology

Mechanical properties were evaluated in high-density polyethylene (HDPE) containing plate-like nanoclay (NC) and particulate nano calcium carbonate (nCaCO₃). A two-step melt mixing method was utilized to prepare nanocomposites withNC/nCaCO₃ hybrid content varying from 7 to 15 wt%. Optimization of the morphological, rheological and mechanical characteristics was carried out via Response Surface Methodology by considering nanofiller loadings and compatibilizer (PE-g-MA) content as independent variables. The findings revealed that a nanocomposite composed of 9 wt% PE-g-MA, 3.5 wt%NC, and 10 wt%nCaCO₃ was optimal. This composition exhibited 50% enhancement in Young's modulus and 8% improvement in yield strength over neat HDPE. Despite the reduced impact strength in all of the prepared nanocomposites, the incorporation ofnCaCO₃ prevented a sudden decrease in the toughness caused by the nanoclay. Further, the fracture behavior observed by scanning electron microscopy (SEM) images suggested that nCaCO₃ activated new toughening mechanisms.     

中心组合设计响应面法优化烟梗提取工艺

为了提高造纸法再造烟叶原料烟梗的提取率,以水为溶剂,以提取时间、提取温度、液料比进行3因素5水平的中心组合设计,采用响应面法优化烟梗提取参数,建立数学模型并进行验证。结果表明,最优工艺条件为：提取温度59℃,提取时间45min,液料比9．1：1,对最佳工艺条件提取率的预测值为38．33％,实测值为38．03％,相对误差仅为0．78％。     

Optimization of mechanical properties of PP/Nanoclay/CaCO3 ternary nanocomposite using response surface methodology

Response surface method of experimental design was applied to optimize the mechanical properties of polypropylene (PP)/nanoclay/CaCO₃ hybrid ternary nanocomposite using three different levels of melt flow index (MFI) of PP, nanoclay, and CaCO₃ contents. The samples were prepared by melt mixing in a lab scale corotating twin screw extruder. The main effect of each parameter on the tensile modulus, tensile strength, and impact strength was extensively discussed. The structure of obtained nanocomposite was studied using X‐ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM) techniques. Tensile modulus and impact resistance of prepared ternary nanocomposite were correlated to considered parameters using a second‐order polynomial model. Also, the optimum values of studied variables were determined using contour plots. The obtained results show that increasing the nanoclay and CaCO₃ contents improve the tensile modulus up to 45%, whereas the optimum value of impact strength, about 54%, is achieved at low concentrations of nanoclay (2 wt %) and CaCO₃ (8 wt %). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

基于响应面法的折流板除雾器分离性能优化

用响应面分析法分析不同排液结构对新式异型折流板除雾器气液分离性能的影响,并对排液结构参数进行优化设计. 通过单因素实验对比筛选对除雾器性能具有显著影响的关键参数,用中心复合设计实验建立响应面多元回归模型,分析影响除雾器性能系数的参数间交互作用,得出最优参数. 结果表明,影响除雾器性能参数的最优取值为分离气速2.6 m/s、排液钩高度7.3 mm、前置排液槽和后置排液槽宽度分别为3.1和2.3 mm. 优化的折流板除雾器性能系数计算值为2.073,实验值为1.875,优化结果较可靠.     

响应面法优化月桂酸单甘油酯的酶催化合成工艺

以月桂酸三甘油酯和甘油为原料,脂肪酶催化甘油解反应合成月桂酸单甘油酯。在单因素试验的基础上,采用响应面分析法进行合成工艺优化。结果表明,含水量(相对于甘油的质量)对月桂酸单甘油酯产率的影响最为显著,且较优合成条件为:恒温振荡器转速100 r/min,酶添加质量分数(相对于底物)5%,n(甘油)∶n(月桂酸三甘油酯)=6∶1,底物质量分数(相对于整个反应体系)51.9%,温度65℃,含水量4.23%,反应时间5 h。在此条件下,月桂酸单甘油酯产率的预测值和实验值分别为81.68%和81.32%,说明二次多项回归模型具有良好的预测性。     

基于响应面法光热-光电膜蒸馏系统优化研究

设计并搭建了太阳能光热-光电方腔型膜蒸馏系统,为研究该系统机理与优化问题,首先以料液进口温度、流量、太阳辐照度为影响因子,膜通量、能耗为响应值,采用响应面法分析各影响因子与响应值间的关系;其次结合中心复合设计法设计实验工况,建立响应值与影响因子的二次多项式回归模型,通过方差分析、实验验证对所建立的模型进行可靠性分析;最后对响应值进行响应面分析与系统优化,获得了系统最佳运行工况和最优膜通量、能耗值,并进行了实验验证。结果表明,系统最佳工况为：料液进口温度为63℃,料液进口流量为232 L/h,太阳辐照度为700 W/m²,在此工况下实际膜通量达到7.28 L/(m²·h),高于预测值6.39 L/(m²·h),两者误差为12.23%,对应的能耗值为10.40 L/(kW·h)。     

响应曲面法多目标优化铜冶炼渣氧压选择性浸出工艺

采用响应曲面法的中心组合设计原理,建立浸出温度、硫酸浓度及液固比及三者之间交互作用对选择性浸出率与矿浆过滤速率的多元二次回归方程,并使用自适应权重粒子群算法对铜冶炼渣氧压硫酸选择性浸出工艺进行多目标优化。结果表明：浸出温度、硫酸浓度和液固比均是影响浸出率和过滤速率的主要因素,各响应因素间存在交互效应,且选择性浸出率与矿浆过滤速率在最佳条件上存在差异。优化后的选择性浸出率和矿浆过滤速率最佳的工艺条件为：温度为204.1℃、硫酸浓度为0.46mol/L、液固比为6.9mL/g,此条件下选择性浸出率为96.95%,过滤速率为399.42L/(m²?h),与验证实验中平均选择性浸出率、平均过滤速率分别为96.57%,398L/(m²?h)相比,偏差较小,预测值与验证实际值吻合好,表明模型选择准确,优化方案可信。     

Characterization and optimization of mechanical properties of bamboo/nanoclay/polyvinyl alcohol/styrene nanocomposites using response surface methodology

This study demonstrates the effects of impregnation of polyvinyl alcohol (PVA), styrene, and nanoclay on the compositional, mechanical, morphological, and thermal properties of bamboo and its nanocomposites (NCs). Design Expert software was used to optimize the materials and modulus of elasticity as well as the modulus of rupture of the composites. Models were obtained with R2 of 0.9999 and 0.998 for the modulus of elasticity (MOE) and the modulus of rupture (MOR), respectively. The MOE and MOR were found to increase significantly after the formation of NC that indicated improvement of mechanical properties of the bamboo NCs. The polymerization of PVA-co-styrene and dispersion of nanoclay were confirmed by the compositional analysis. The X-ray diffraction analysis showed that the degree of crystallinity was slightly improved upon impregnation with PVA-co-styrene, while reduction in the hydroxyl groups was observed using the Fourier transform infrared. The scanning electron microscopy observation showed tightly filled cell cavities of the bamboo matrix. The thermal stability of the formed NCs were found to be slightly less stable than the raw bamboo (RB) with the differential scanning calorimetry showing low glass transition temperature and the thermogravimetric analysis showed lower decomposition temperatures for the NCs compared to RB as a result of plastic property of the styrene.     

Optimization of fractional crystallization on crude biodiesel purification via response surface methodology

In order to improve separation and purification efficiency of biodiesel, an alternative method has been explored which is fractional crystallization. In this study, glycerol that has a higher melting point was formed as a solid phase while the pure biodiesel was remained in liquid phase during the crystallization process. Response surface methodology (RSM) and central composite design (CCD) were employed to search for the optimum operating conditions. The best responses were 0.117 and 46.734% for effective partition constant (K) and concentration efficiency (Eff), respectively, while the optimum operating conditions were coolant temperature at ?9.5°C and stirring rate at 362 rpm.     

Optimizing nanoencapsulation of Heracleum lasiopetalum by response surface methodology

This study was carried out to optimize formulation for Heracleum lasiopetalum (golpar) extract nanoencapsulation by response surface methodology (RSM). The primary water-in-oil emulsion was fabricated by (5%–10%) golpar extract (GE), (40%–35%) emulsifier span 80 (EM), and (50%–60%) sunflower oil (SO). The coating materials were the mixture of Lepidium sativum seed gum (LSG) and whey protein concentrate (WPC) at different ratios (1:0, 1:1, and 0:1). The yield of nanoencapsulation of GE, particle size, and zeta potential was investigated as responses of RSM. The optimal formulation for water-in-oil-in-water emulsion of GE were SO: 50.46%, GE 9.52%, and EM: 36.30% in LSG, SO: 57.07%, GE: 7.12%, and EM: 30.85% in LSG:WPC, and SO: 54.98%, GE: 9.05%, and EM: 39.87% in WPC coating. In conclusion, the nanoencapsulation of GE prepared with the optimized formulation by RSM ensures the gradual release and higher stability to sedimentation during storage with nanometric size and high yield of encapsulation. The nanocapsules of GE can be used as a natural antioxidant in food systems.     

响应面法优化复合酶提取牛皮胶原多肽的工艺

以实验室自制的牛皮胶原蛋白为原料,探讨复合酶提取牛皮胶原多肽的工艺。以牛皮胶原蛋白的水解度为评价指标,确定木瓜蛋白酶和胰蛋白酶的添加顺序和添加比例,同时单因素法获取酶解工艺参数的优化区间,响应面法优化复合酶酶法提取胶原多肽的工艺参数,实验结果表明,从牛皮胶原蛋白中提取胶原多肽的最优条件为：木瓜蛋白酶和胰蛋白酶按酶活力比3:1同时添加,加酶量650u/ml,酶解介质pH7.0,酶解温度50℃,酶解时间7h,在此工艺条件下得到的牛皮胶原蛋白的水解度可达到32.02%。     

响应面法优化以重组大肠杆菌发酵生产类人胶原蛋白过程

In order to improve the production of human-like collagen Ⅲ (HLC Ⅲ) by fed-batch culture of recom-binant Escherichia coli BL21, the Plackett-Burman and Box-Behnken design were applied to optimize the fermen-tation process parameters.Three variables (induction time, inoculum age and pH), which have significant effects on HLC Ⅲ production, were selected from eight variables by Plackett-Burman design.With the regression coefficient analysis in the Box-Behnken design, a relationship between HLC Ⅲ production and three significant factors was obtained, and the optimum levels of the three variables were as follows: induction time 3.2h, inoculum age 12.6 h and pH 6.7.The 3D response surface plots and 2D contour plots created by the Box-Behnken design showed that the interaction between induction time and pH and that between innoculum age and pH were significant.An aver-age 9.68 g·L~(-1)HLC Ⅲ production was attained in the validation experiment under optimized condition, which was 80% higher than the yield of 5.36 g·L~(-1) before optimization.     

聚砜基阴离子交换膜响应面法优化设计及制备

选择低毒、无致癌毒性的材料,创新性地使用冰浴手段,在相对温和的反应条件下制备出氯甲基化聚砜（CMPSF）,并采用响应面法优化了CMPSF的制备条件。结果表明,当冰浴温度3.3℃、三甲基氯硅烷用量15.63 ml、反应温度35℃、溶剂量500 ml、搅拌速度200 r·min^-1、催化剂用量1.52 ml、反应时间40 h时,CMPSF的氯甲基化程度可达最大值1.443 mmol·g^-1。进一步将优化后的CMPSF原料季铵化,最终制得聚砜阴离子交换膜（PSFAEM（。利用FT-IR、¹H NMR和XPS对各产物的化学结构进行了表征,并测定了阴离子交换膜的主要性能,结果表明所制阴膜的离子交换容量为1.2 mmol·g^-1、面电阻为1.05 Ω·cm²、含水量为0.42 g·g^-1、溶胀率为25.47%,由热重分析结果可知季铵基团脱落温度为140℃,所制阴膜的性能满足实际应用中对阴离子交换膜的要求。     

响应面法优化制备LDHs-CRMA复合改性沥青及其表征

采用熔融共混法,以克拉玛依90#沥青为原料,Mg-Al水滑石(LDHs)与废橡胶粉(CR)作为改性剂,制备了具有抗紫外老化性能的水滑石/废胶粉复合改性沥青(LDHs/CRMA),并对其软化点、针入度指数(PI)、延度进行了测试。通过Hassan数学方法将三个指标"归一化"得到总评"归一值",采用响应面分析法建立总评"归一值"与各因素之间的Box-Behnken数学模型,得到了LDHs/CRMA的最优制备工艺条件为:剪切温度173℃、剪切时间89 min、剪切速率3500 r/min。通过紫外老化模拟实验对复合改性沥青的抗老化性能进行了评价,结果表明,引入水滑石可以减少沥青老化过程中含氧官能团的产生,抗紫外老化性能得到了明显提高。     

Process optimization for foam separation of yak whey protein by response surface methodology

In order to recovery whey protein from yak whey wastewater effectively, a facile method of foam separation to be suitable for the local nomadic herdsmen in Qinghai-Tibet Plateau has been established in this research. The effects of the four factors, protein concentration, gas velocity, temperature and pH, on the performance of foam separation were investigated. Based on the single factor experiments, the response surface software was adopted to optimize and to investigate conditions of foam separation for whey protein, and the optimal conditions were found to be protein concentration of 120 μg/mL, gas velocity of 310 mL/min, temperature of 41°C and pH of 3.8, respectively. The as-obtained results of verification experiments, recovery percentage 88.3% and enrichment ratio 9.25 showed that foam separation technique was a simple equipment and environmental compatibility method to separate whey protein from yak whey wastewater.     

Preparation of sorbitol fatty acid polyesters,potential fat substitutes: Optimization of reaction conditions by response surface methodology

Effects of the reaction temperature, reaction time, mole ratio of fatty acid methyl esters (FAME) to sorbitol, and mole ratio of fatty acid sodium soaps (FASS) to sorbitol on yields of sorbitol fatty acid polyester (SFPE) were examined with a response surface methodology. The optimum reaction conditions selected with response surface analysis were as follows: reaction temperature, 144°C; reaction time, 6.65 h; mole ratio of FAME to sorbitol, 10.7∶1; and mole ratio of FASS to sorbitol, 0.77∶1. Under these reaction conditions, the experimental yield of sorbitol fatty acid polyester (mean value: 92% range: 89–94%) obtained from seven replications was close to the predicted value (94%) calculated from the polynomial response surface model equation. The response surface methodology approach used in this study was able to predict the reaction conditions necessary for a high yield of sorbitol fatty acid polyester.     

钢结构防火涂料配方的响应面法优化

引言钢结构建筑的防火历来是备受业界关注的领域,在众多保护措施当中,防火涂料因其施工方便,不受钢结构形状、面积限制,防火性能优异等优点而在钢结构建筑中广泛使用。其中超薄膨胀型钢结构防火涂料具有粒度细、涂层薄、施工方便和装饰性好等特点,能在满足钢结构防火要求的同时