国内外大豆蛋白质纤维研究概况

国外从19世纪末、20世纪初即开始对再生蛋白质纤维进行研究,1935年意大利科学家、1938年英国ICI公司、1939年Corn Product Refining公司曾分别探讨从牛乳、花生蛋白质、玉米、大豆豆粕中提取蛋白质,再进行纺丝。20世纪40年代初,美、英研制了酪素纤维;1945年美、英又研究了大豆蛋白质纤维;1948年美国通用汽车公司从豆粕中提取了大豆蛋白质纤维,但大多因为纤维性能较差,无法进行纺织加工而中断研究。近年日本东洋纺公司开发的牛奶蛋白质纤维实现了工业化生产,由于100公斤牛奶只能提取两公斤蛋白质,使得制造成本过高,且纤维耐热性差,在干热120°C以上时易泛黄,强力下降,因此至今仍无法大量推广使用。而我国的大豆蛋白质纤维制造技术可以从100公斤豆饼中提取40公     

花青素掺杂的壳聚糖杂化溶液对蚕丝的染色性能

本文研究了葡萄籽来源的花青素不同浓度及p H条件下的紫外可见吸收光谱,利用花青素掺杂的壳聚糖/镁离子溶液对蚕丝进行染色,探讨不同工艺条件如温度、时间、染料浓度、金属镁离子用量对蚕丝染色效果影响。     

废弃红茶中脂溶性茶绿色素的提取工艺研究

采用有机溶剂从废弃红茶中提取脂溶性茶绿色素,用紫外可见分光光度计测量吸光度方法,分别研究了提取溶剂、提取液料比、提取温度和提取时间对提取效果的影响,由正交试验得出最佳提取条件。研究结果表明:无水乙醇为提取溶剂,液料比为15∶1(mL∶g),提取温度50℃,提取时间30min时,脂溶性茶绿色素的提取率为12.57%。     

加拿大油砂产业化项目或将减少1／3

据海外媒体报道,美国第二大上市工程公司雅各布斯工程公司首席执行官克雷格·马丁日前说,由于油价大幅下跌,从加拿大油砂中提取原油的产业化项目有可能减少三分之一。     

美伐他汀提取工艺研究

研究从发酵液中提取美伐他汀的工艺条件。通过单因素实验确定了从美伐他汀发酵液中提取美伐他汀的最佳工艺条件。结果表明,醋酸丁酯作为提取溶剂时,其最佳工艺条件如下:提取温度为50℃,物料比(醋酸丁酯体积(mL):菌丝质量(g))为8:1,提取时间为3 h,闭环温度为70℃,闭环时间为6 h。本工艺简便,收率高,适用于工业化生产。     

欧盟立法限制车用生物燃料 生物燃料是否可靠再成焦点

欧盟委员会1月23日审议通过了一项关于车用生物燃料的法案,该法案禁止欧盟企业进口以破坏性手段生产的车用生物燃料。因为最近有调查报告表明,为提取清洁的生物燃料而大规模砍伐植物,反而可能损害环境。此项立法建议的内容包括:从国外进口的生物燃料必须标明对环境影响的利弊大小;从生长在森林、湿地、草地的植物中提取的生物燃料被禁止进口。有环保组织称,东南亚的棕榈林被砍伐所增加的二氧化     

超临界流体技术

超临界流体技术早期的工业化应用是萃取,用其代替有机溶剂从天然材料中提取有效成分,广泛应用于食品、医药、香料等领域,如从咖啡中取出咖啡因,从啤酒花中提取啤酒酿造材料,从中草药中萃取药物有效成分,也用于从花朵、芳香植物中获取香精、天然色素等.以超临界流体作为介质进行有机合成或聚合反应以制备材料的发展也十分迅速.此外,超临界流体在高效液相色谱分析技术及制备纳米粉末等方面的应用也有很大的开发空间.     

简讯

北京奥运国旗手服装使用牡丹红在北京奥运会开幕式现场,将有10位身穿红色上衣、黄色裤子的国旗手。他们的服装将用从洛阳牡丹的花瓣中提取的染料着色。此次北京奥运国旗手服装采用的两种染料,“国旗红”主要从霓日红、卷叶红、胡红等6种红色系的牡丹中提取。“国旗黄”从海黄     

胡萝卜素的提取工艺研究

目前,生产胡萝卜素的方法主要有化学合成、生物发酵和动植物天然提取。通过化学合成或生物发酵生产的胡萝卜素存在结构单一,甚至有致畸形的作用或百分含量不高等缺点。天然提取法提取胡萝卜素的过程简单,适宜常规化生产。业内人士以金盏菊花为原料研究了胡萝卜素的提取条件。研究了从胡萝卜中提取β-胡萝卜素的工艺,用石油醚-丙酮混合液提取,提取率达90%以上,研究表明,混合溶剂优于单一溶剂。胡萝卜素分子中均含有共轭多烯结构,在丙酮、石油醚、己烷、二硫化碳等中溶解度较大,不溶于水、丙二醇等极性溶剂。不同提取剂有不同的适用范围,如乙…     

乡镇煤矿维简费不宜一刀切

这几年乡镇煤矿提取的维简费逐步增多。山西省在1980年7月1日前,要求社队煤矿从企业留利中提取一定数量的更新改造资金,比例由各地自定。从1981年7月1日起,改为从生产成本中吨煤提取1元。1983年3月1日后,维简费又增加到 2.5元。但1983年前,多数乡镇煤矿并没有提足,只是从利润中提取一定的更新改造资金或公积金。1984年第4季度后,随着地方国营煤矿维简费增加到吨煤4元,乡镇矿也相应提到了吨煤4元,并列入成本。提高乡镇煤矿维简费的指导思     

Benefit cost analysis of an import access request

Invasive species outbreaks are often unintended side effects of trade. In this paper partial equilibrium trade models and stochastic bioeconomic impact simulation models are combined to present a benefit cost analysis template to assess market access requests. The template is used to assess the likely regional economic welfare implications of a decision by Australian biosecurity regulators to allow the Chilean table grape industry access to the national table grape market. We show that consumption benefits expected to accrue to Western Australia are exceeded by increases in likely invasive species damage resulting from grape imports, implying that insufficient consumer gains are grounds to deny market access.     

The performance implications of “grow or buy” decisions in the wine industry

This paper investigates how wineries’ decisions to grow or buy their provisions of grape affect their viticultural performance. While previous literature in agrarian economics suggests a direct association between vertical integration and performance, this research largely neglects the impact of transaction cost variables on governance mode choice and firm performance. This paper first demonstrates that neither outsourcing nor vertical integration per se result in superior performance; rather, a winery’s viticultural performance is contingent upon the alignment of winery’s governance decisions with the predictions of transaction cost theory.     

Assessing the impact of improved agricultural technologies on household income in rural Mozambique

In many areas of Africa, rural livelihoods depend heavily on subsistence farming. Using improved agricultural technologies can increase productivity in smallholder agriculture and thus raise household income and reduce poverty. Data from a nationally representative rural household survey from 2005 is used to assess the impact of four technologies – improved maize seeds, improved granaries, tractor mechanization, and animal traction – on household income in Mozambique. To ensure the robustness of the results, three econometric approaches were used: the doubly-robust estimator, sub-classification and regression, and matching and regression. The results show that, overall, using an improved technology did not have a statistically significant impact on household income. This may be associated with a widespread drought that occurred in 2005. Despite drought, distinguishing between households based on propensity score quintiles revealed that using improved technologies, especially improved maize seeds and tractors, significantly increased the income of those households who had better market access. Thus, to allow households to benefit from the use of improved technologies, policy makers need to reduce structural impediments to market participation by ensuring adequate road infrastructure and enabling access to markets.     

Indian farmers’ valuation of yield distributions: Will poor farmers value ‘pro-poor’ seeds?

Potential poverty traps among the rural poor suggest a need to reduce poor farmers’ vulnerability by stabilizing crop yields and limiting yield losses. Advances in biotechnology will help address this need directly with crops that tolerate climate fluctuation or resist biotic stresses. Evaluating ex ante how farmers will value these ‘pro-poor’ seeds is important for delivery design, but also challenging. This paper describes an experimental economic approach to understanding farmers’ valuation of such seeds. Using data from a survey and experiment, I assess Indian farmers’ valuation of changes in the mean, variance, and skewness of payoff distributions. These farmers value increases in expected value, but seem indifferent about higher moment changes in payoff distributions. Farmer traits such as wealth and risk exposure affect their valuation of these changes only mildly. While various limitations to the experimental approach must qualify practical implications of these findings, the experiment demonstrates the viability of conducting valuation experiments with open-ended questions in developing countries.     

Maize protection in Zambia

A major preoccupation of agricultural policy makers in the 1970s has been how to obtain maximum benefit from new high-yielding seeds. ‘Tailored packages’ have been developed to suit conditions in different countries, specialized training has been arranged for farmers to help them cope with the techniques needed for the new seeds, and banks, at least in some countries, have extended their activities deeper into the rural areas. Some attempts have also been made to avoid the ‘freezing out’ of small farmers for whom the new seeds, with their demands for precise applications of water and fertilizers, were likely to be a risky business. The emphasis has been on increased output. Less effort has gone into programmes designed to deal with a problem that the high-yielding strains create once they have been grown and harvested — an increase in post-harvest losses. Estimates suggest that between 20% and 40% of the grain produced in developing countries each year ends up nourishing insects, rodents and birds or is otherwise spoiled by fungi. The food lost in Africa alone each year could feed 55 million people. India loses sufficient grain to feed 50 million people a year.The high-yielding varieties of seeds are even more susceptible to loss than traditional seeds because they cannot be kept securely in traditional storage facilities. A good example of this problem — as well as an innovation which is attracting attention from many other countries — is in Zambia where maize is the staple crop.     

The economics of adventitious presence thresholds in the EU seed market

Since settling on its mandatory labeling rules for genetically modified (GM) foods in the late 1990s, the European Commission has considered a number of times setting tolerance levels (thresholds) for the accidental presence of GM material in conventional seeds. In every case, it has opted to defer the decision. In the absence of such thresholds, current European labeling laws require that seeds be labeled as GM if they contain any detectable trace of GMOs approved for cultivation in the EU. Conventional seeds with detectable traces of GMOs that have not been authorized for cultivation cannot be sold in the European market altogether. As the acreage of GM crops has continued to grow at a fast pace around the world, industry calls to the EU Commission for setting “practical” adventitious presence (AP) thresholds for conventional seeds in the EU have multiplied. In this paper, we examine the economics of alternative AP thresholds for conventional seeds in Europe from the perspective of those who must comply with the regulation – EU seed firms. Specifically, we first examine the operational changes that might be necessary for seed firms to comply with alternative AP thresholds for conventional seeds. Then, we analyze the associated market uncertainties, compliance costs and their implications on firm and industry competitiveness.     

Impact of contracts in high yielding varieties seed production on profits and yield: The case of Nepal

Nepal’s population continues to grow, but the agricultural sector’s performance remains almost stagnant. This has led to a decline in the per capita availability of food. Increasing agricultural productivity is the key to agricultural growth, and one strategy for increasing agricultural productivity is to use improved seeds. This study investigates the impact of contract farming (CF) in high yielding varieties (HYV) of paddy seed production on costs, yield, and profits of smallholder farms in Nepal. Using farm-level data and a non-parametric propensity score matching estimator, the study finds a significant positive impact of contract HYV seed farming on revenues, profits, and yield, and a significant negative impact on total costs of production. Additionally, very small farms (⩽0.43 ha) with CF in HYV paddy seeds tend to gain the most when it comes to yield per hectare. Our estimates reveal that the average smallholder household in Nepal engaged in CF with input conditions receives higher profits. However, farmers engaged in CF with output conditions tend to have higher yields but smaller profits. Finally, farmers engaged in CF in HYV paddy seeds with both input and output conditions have the highest yield gains and significantly higher profits.     

菌种制备环境温度控制方法的改进

针对菌种制备中传统温度控制方法的缺点,提出利用新型ＪＡ系列晶闸管调整器实现环境温度的连续ＰＩＤ控制,从而提高了控制精度,降低了故障率,为菌种制备提供了良好条件。     

Assessing the effectiveness of a technical assistance program: The case of maize seed relief to vulnerable households in Zimbabwe

The recent economic downturn in Zimbabwe impoverished the majority of households. To assist vulnerable rural households improve their food security, the British Department for International Development implemented a seed relief program from 2003/2004 to 2005/2006 that emphasized recycling of maize open pollinated varieties (OPV). Using data collected from 597 households in six districts in 2006, this study assesses the effectiveness of the program in terms of its targeting of beneficiaries, the flow of information from participating NGOs to beneficiaries on the need to recycle the seeds, and the level of recycling done at the end of the program. The empirical results suggest that the targeting method participating NGOs use inadvertently excludes relatively vulnerable households while including large proportions of relatively well-endowed households in the program. The choice of varieties to distribute is guided more by the ecological adaptability of available commercial seeds and less by preferences of beneficiaries. Notwithstanding the fact that seed selection information is critical in encouraging beneficiaries to recycle distributed seed, not all of them received it. In conclusion, it may be stated that the program undoubtedly contributed to increased food productivity by vulnerable households but its overall effectiveness could have been enhanced through (i) the involvement of the beneficiaries in the choice of types of seed to be distributed, (ii) better targeting of beneficiaries, and (iii) improved information flow between NGOs and beneficiaries.     

Zimbabwe’s Agricultural Recovery Programme in the 1990s: an evaluation using household survey data

During the 1990s, the Government of Zimbabwe implemented an Agricultural Recovery Programme to help smallholder farmers recover from repeated severe droughts. The programme aimed to provide drought-affected smallholders with crop packs (free seeds and fertiliser) and mechanised tillage services. This article evaluates the coverage, poverty-sensitivity and impact of the programme using a more in-depth analysis of household survey data than has been done to date. The programme’s tillage component was unsuccessful, repeatedly reaching less than 5% of its target group; the crop pack component, however, reached four-fifths or more of its target group. Most of the poorer households received crop packs, but richer households were slightly more likely to get them. Those who did receive crop packs planted larger areas under staple crops, regardless of their poverty status. These findings are generally robust for a range of poverty proxies. Unfortunately, there is no clear evidence on the impact, if any, of crop packs on grain yields. Crop packs—properly attuned to local agro-ecological conditions—may serve a useful role in post-drought recovery. Steps must be taken, however, to ensure that all the poor receive crop packs. Attempts by government to provide mechanised tillage to hundreds of thousands of smallholder households are not recommended.