Lactic acid production from dining‐hall food waste by Lactobacillus plantarum using response surface methodology

BACKGROUND: Food waste generally has a high starch content and is rich in nutritional compounds, including lipids and proteins. It therefore represents a potential renewable resource. In this study, dining‐hall food waste was used as a substrate for lactic acid production, and response surface methodology was employed to optimise the fermentation conditions. RESULTS: Lactic acid biosynthesis was significantly affected by the interaction of protease and temperature. Protease, temperature and CaCO₃ had significant linear effects on lactic acid production, while α‐amylase and yeast extract had insignificant effects. The optimal conditions were found to be an α‐amylase activity of 13.86 U g^?1 dried food waste, a protease activity of 2.12 U g^?1 dried food waste, a temperature of 29.31 °C and a CaCO₃ concentration of 62.67 g L^?1, which resulted in a maximum lactic acid concentration of 98.51 g L^?1 (88.75% yield). An increase in inoculum size would be appropriate for accelerating the depletion of initial soluble carbohydrate to enhance the efficiency of α‐amylase in dining‐hall food waste fermentation. CONCLUSION: A suitable regression model for lactic acid production was developed based on the experimental results. Dining‐hall food waste was found to be a good substrate for lactic acid fermentation with high product yield and without nutrient supplementation. Copyright © 2008 Society of Chemical Industry     

A disposable sensor based on immobilization of acetylcholinesterase to multiwall carbon nanotube modified screen-printed electrode for determination of carbaryl

A simple method has been devised for immobilization of acetylcholinesterase (AChE) covalent bonding to a multiwall carbon nanotube (MWNT)-cross-linked cellulose acetate composite on a screen-printed carbon electrode (SPCE) and a sensitive and disposable amperometric sensor for rapid determination of carbaryl pesticide is proposed. The immobilized enzyme was preserved on this film because of the excellent biocompatibility and non-toxicity of cellulose acetate. Based on the inherent conductive properties of the MWNT, the immobilized AChE had greater affinity for ATCl and excellent catalytic effect in the hydrolysis of ATCl. MWNT improved the interface enzymatic hydrolysis reaction and increased the amperometric response of the sensor. Under optimum conditions, the inhibition of carbaryl on AChE increased linearly with the increasing concentration of carbaryl in two ranges, from 0.01 to 0.5 μg mL⁻¹ and from 2 to 20 μg mL⁻¹, with the correlation coefficients of 0.9985 and 0.9977, respectively. The detection limit was 0.004 μg mL⁻¹ taken as the concentration equivalent to 10% decrease in signal. The sensor showed acceptable stability, accuracy and could be fabricated in batches, thus it is economic and portable. This type of disposable enzyme-based amperometric sensor has extensive application potential in environmental monitoring of pesticides.     

发展3G时不我待--兼析民族3G标准的发展

当今通信业最热门的话题非3G莫属。尽管2000年3G许可证的拍卖引发了欧洲乃至全球电信经济的萧条,但中国实行的“积极试验,谨慎决策”的政策,确保了电信业的快速增长。如2001年和2002年中国的电信业务收入分别增长了16.1%和14.4%,继续高于GDP的增长速度。今天,3G在国际市场上正步入良性发展轨道,中国移动通信市场也在向纵深发展,包括促进有效竞争、支持民族3G标准TD-SCDMA的发展和应用等。一、中国发展3G迫在眉睫1.用户需要3G中国市场对移动话音、移动新业务和新应用的需求潜力十分巨大。2002年底,中国移动通信的用户数(中国移动+中国…     

Comparison of physical characteristics and cell culture test of hydroxyapatite/collagen composite coating on NiTi SMA: electrochemical deposition and chemically biomimetic growth

A hydroxyapatite (HA)/collagen (COL) composite coating on NiTi shape memory alloy (SMA) was prepared by eletrochemical deposition (ELD) in modified simulated body fluid (MSBF). To draw comparisons of physical characteristics and bioactivity of the composite coating, the HA/COL composite coating was also prepared by chemically biomimetic growth (BG) and the ELD coating was re-soaked in MSBF again for further biomimetic growth (called EBG method in this paper). It was indicated that the c-axis of HA crystals was oriented parallel to the longitudinal direction of the COL fibril in BG and EBG coating, which could not found in ELD coating. The EBG method could induce a denser, thicker and better crystallized HA/COL coating. The cell culture test indicated that the BG coating presented better cell biocompatibility.     

GIS数据库中的数据挖掘

首先探讨了DM在GIS中应用的必要性和可能性,然后讨论了GIS数据库中的DM可以发现的知识类型、可以使用的方法,可以采用的DM系统原型,最后简单介绍了DM对GIS的贡献。     

非标压力机箱形主梁全约束优化设计

根据非标设备结构优化问题的特点,给出满足《钢结构设计规范》(GBJ17 88)规定的箱形主梁全约束优化设计方 法。将编制的内罚函数法优化程序应用于主梁的设计,计算结果表明,该优化方法可应用于实际设计。     

油气吸收回收系统的研究及工业应用——(Ⅱ)工业试验及效果分析

在油气吸收回收系统中型试验的基础上，开发了常温常压吸收法工业化油气回收系统，并进行了工业应用。结果表明，该油气回收系统平均回收率可达95．13％，每年可回收汽油529t；装车期间装车口周围环境大气中总烃浓度平均降低98．06％。企业通过实施油气回收系统，节能及经济效益明显，且很好地改善了装车场所的作业环境，克服了油气排放带来的安全隐患。     

小城镇融资 路有几条

事物最好的形态该是什么样子?或许因为语境的不同答案就相去千万里。今天的小城镇建设即是如此:虽然还残留着“村村点火,户户冒烟”的“原生态”农村工业化的痕迹,但毕竟遍地开花般的设镇模式已开始以乡镇合并的方式在压缩数量,而一些小城镇的聚合效应也已慢慢地上升为一种真正的“榜样”力量。换句话说,是时移世异。1887个全国重点镇就是“榜样”。从19800个建制镇中脱颖而出,它们成为这个人口大国雄心勃勃加快城镇化进程、全面建设小康社会的尖兵。只是,自从前几年国有商业银行从农村地区大幅缩编给县域金融留下一片真空地带,小城镇本就不…     

维氏硬度检测中不确定度初探

通过分析维氏硬度检测中的不确定度，计算了各不确定度分量所占的权重，得到HVlO(440--738)范围内的相对不确定度为1．3％--1．7％。     

聚合酶β在肝癌细胞DNA辐射损伤修复中的作用

利用第二军医大学裸鼠移植性肝癌细胞（ＳＭＭＣ－ＬＴＮＭ）和不同的ＤＮＡ聚合酶选择性抑制剂ＮＥＭ与ｄ２ＴＴＰ，探讨了肿瘤细胞核中ＤＮＡ聚合酶β参与γ射线辐射损伤ＤＮＡ修复的作用特点，结果表明，该酶参与真核细胞γ射线辐照损伤的ＤＮＡ修复合成，是一种重要的ＤＮＡ修复酶，与正常肝细胞相比，ＳＭＭＣ－ＬＴＮＭ肝癌细胞ＤＮＡ聚合酶β的ＤＮＡ修复合成反应速度快，修复能力强，提示某些肿瘤细胞中该酶的ＤＮＡ辐射损伤