超临界CO_2流体萃取技术的应用研究

本文主要对超临界二氧化碳(CO_2)流体萃取技术原理和重要影响因素进行了简单介绍,并阐述了超临界CO2流体萃取技术在金属离子、环保技术、食品工业、石油炼制、香料工业、医药卫生等方面的应用。     

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.     

超临界流体萃取技术在天然药物提取中的应用分析

超临界流体萃取技术是天然药物提取的一种常用的应用方式,其是将超临界流体作为一种溶剂,将天然药物中的可溶组分的溶质从固体或者液体当中萃取出来,这是一种分离技术。超临界流体萃取技术在应用,能够将天然药物中成分最大限度地保存下来,提高天然药物的提取纯度。因此,文章对超临界流体萃取技术在天然药物提取中的应用进行了分析,并针对性地提出了发展建议,以供参考。     

中药材中农药残留现状及其应对策略

中药材中农药残留超标问题一直备受关注,农药残留超标不但影响中药的疗效,对人体健康造成伤害,同时也会制约中药材走向国际市场。文章研究了农药分类及特点,阐明了农药残留的检测方法和技术,为检测人员选择合适的检测手段提供参考依据;分析了中药材被农药污染途径,总结了中药材农药残留的预防手段和降解技术,为中药材种植、运输、生产加工和贮存企业降低农药残留提供技术支持,为中药材的科学监管提供技术保障。     

食品农药残留检测技术的要点

食品中存在农药残留会严重危害人体健康,导致人体出现急性中毒、特殊中毒以及慢性中毒等现象。为有效维护食品安全,需要在食品流入市场前采取科学的方法检测农药残留。文章主要通过分析食品农药残留的危害,讨论食品农药残留检测的重要性,分析目前食品农药残留检测中常用的技术,提出相关技术应用要点。     

气相色谱-质谱法测定土壤中17种有机磷农药

建立了一种加速溶剂提取-固相萃取净化-气相色谱-质谱法同时测定土壤中17种有机磷农药的分析方法,采用丙酮-正己烷(1∶1,体积比)为提取液对样品进行加速溶剂萃取,萃取液经弗罗里硅土固相萃取柱净化,用气相色谱-质谱法测定,内标法定量。结果表明：相对响应因子的相对偏差为8.0%～18.4%,检出限为0.01～0.05 mg/kg;回收率范围为55%～140%,相对标准偏差为3%～18%,均满足测定相关要求。该方法操作简单、灵敏度高、准确性好,适用于实验室内多种有机磷农药残留的同时测定。     

异菌脲在梨和土壤中残留量的测定方法

建立了异菌脲在梨和土壤中气相色谱分析方法。梨、土壤样品用乙腈提取,Florisil固相萃取小柱净化,淋出液浓缩后用正己烷定容,气相色谱仪电子捕获器检测。试验结果表明,异菌脲的含量与峰面积之间呈线性关系,异菌脲的最小检出量为0.005ng。对于梨样本,异菌脲最低检测量为0.01mg/kg,添加平均回收率为94%～107%,变异系数为3.2%～6.5%;对于土壤样本,异菌脲最低检测量为0.01mg/kg,添加平均回收率为98%～110%,变异系数为4.0%～10.5%。结果表明该残留分析方法的灵敏度、准确度、精密度等均符合农药残留检测的要求。     

固体溶质在含夹带剂超临界CO2中溶解度的计算

针对超临界流体萃取技术是一种绿色新型分离技术的特点,选用适合超临界体系特点的状态方程、混合规则及方程参数的计算方法,建立了计算溶质在含和不含夹带剂的超临界CO₂中溶解度的数学模型,并给出了模型的计算过程。     

固相萃取在高效液相色谱法紫外检测污水处理分析

固相萃取--高效液相色谱法紫外检测是一种高效快速的检测方法,并且具有抗干扰性强、回收率高等优点,在分析化学中具有重要地位。本文以检测污水中直链烷基苯磺酸盐和地塞米松两个实例,对固相萃取--高效液相色谱法紫外检测在污水处理中的应用进行了分析。     

农药的分析检测及新技术研究

随着农业生产规模的增大,在农业上使用的农药种类越来越多,在各种农药类型中,有机磷农药应用的范围最广,毒性也最大。如果人类误食含有有机磷农药残留的食物会引起严重的食物中毒。农药残留严重威胁着农产品的质量安全以及人们的生命安全,因此对于农药检测必须加以重视。文章在此基础上,论述了农药检测技术的应用,并详细分析新技术应用的具体措施。     

终极所有权结构研究——来自中国上市公司的经验证据

La Porta et al.(1999)通过追溯控制链来鉴别终极所有者的研究范武是研究所有权结构方法论上的新进展。本文以直接所有权研究方法和La Porta et al.(1999)的研究方法为基础,为中国上市公司的所有权结构建立了一个新的分析框架,实证研究表明,我国上市公司的所有权结构高度集中。境内法人直接控制了绝大多数上市公司,国家和境内自然人更多地通过境内法人对上市公司实施间接控制.从而成为上市公司最重要的终极所有者,上市公司的终极所有权结构与直接所有权结构存在明显差异。研究结论反映出我国现有股本类型的分类方式存在弊端、中小投资者缺乏有效的法律保护以及上市公司内部公司治理机制薄弱等问题。     

超临界水在化工领域中的应用

超临界技术是近几年来化工行业研究的热点。纯水在超临界状态下具有特殊的物理化学性质,可以作为很多化工过程的良好的溶剂,具有反应速度快、时间短、反应彻底、副产物少等优点,国内外在这方面的研究很多,并已部分地实现了工业化。介绍了超临界水的物理化学性质以及它在纤维素水解、废水处理和超细造粒等方面的作用。     

多种创新方法集成与应用研究

本文深入研究了创新方法内涵，对各种创新方法进行系统梳理与分类，在产品生命周期全过程各个创新要素和创新内容进行选择、整合和优化基础上，利用复杂适应系统理论，建立多种创新方法集成与应用系统，在产品创新的整个过程中形成模块儿化的互补优势，使新产品较以往来说功能上呈现倍增，并适应进化规律，从根源上促进创新的发展。     

薯蓣皂甙元提取方法的研究进展

薯蓣皂甙元是薯蓣皂甙的水解产物,它是许多重要甾体激素的前体物质。介绍了薯蓣皂甙元的结构、化学组成和近年来的提取方法,综合比较了常规酸水解法、自然发酵法、超声法、酶水解法、超临界流体萃取法等方法的优缺点,认为超临界流体萃取法较为先进且对环境无污染,并对今后的研究方向提出了展望。     

Public Private Partnerships in food industries: A road to success?

Recent food safety crises have led to the development of new collaborations between public authorities and food operators in monitoring food safety. To date, most of the literature has analyzed these collaborations as linked to a regulatory process and as a mean to comply with regulatory standards. In this paper, we take another stand and consider them as specific embedded institutions (meso-institutions) analysing them as Public Private Partnership specific to food safety provision. This new perspective allows us to take into account both information asymmetries and the industry-wide dimension of such programmes. Our overall intention is to provide a general enriched theoretical framework to highlight aligned incentive mechanisms in such partnerships. We then apply our framework to two case studies in order to better understand the main mechanisms at work that could explain their specific functioning and resilience. The two case studies are the cattle traceability system in Quebec (Canada) and monitoring programmes for pesticide residues in the French imports industry of fresh produce.     

Overlap of US FDA residue tests and pesticides used on imported vegetables: Empirical findings and policy recommendations

In the United States, the Environmental Protection Agency (EPA) registers pesticides and sets crop-specific tolerances while the Food and Drug Administration (FDA) enforces EPA regulations by testing plant-based foods for pesticide residues. Pesticide treatment histories are almost always unknown, especially on imported produce, posing an empirical question: to what extent do FDA’s residue testing methods used on imported produce correspond to the pesticides used on the crops? In this article I show that FDA residue testing would have missed residues of the majority of pesticides used on two crops exported to the US from Costa Rica in 2003, suggesting that FDA residue testing on imported produce is inadequate in its coverage. Policy recommendations discussed include better communication of US tolerances to exporters around the world; increased testing for pesticides, especially fungicides, that are currently not part of FDA’s regular testing procedures; and the creation of price floors and fair trade relationships in the transnational vegetable market to support farmers’ attempts to comply.     

中药国际化途径探讨

目的探讨以中医为依托的中医国际化途径。方法对中药出口贸易现状进行分析,指出中药出口存在的障碍,并且针对问题提出相应的解决措施。结果与结论中医出口应以提高中医药临床疗效、加强中西医结合、加快中医术语的国际化为基础,同时加大中医的宣传力度,以推动中药出口。     

Why is the food traceability system unsuccessful in Taiwan? Empirical evidence from a national survey of fruit and vegetable farmers

Food traceability systems allow the consumers or administrative authorities to trace the origins or ingredients of food products. Given the expressed concerns for food safety, the promotion of food traceability systems has occurred in many countries. Although a considerable body of literature has examined the consumer responses in regard to food traceability, relatively little is known about the producers’ adoption behaviors. To fill this knowledge gap, this paper investigates Taiwanese farmers’ participation decision in relation to the Taiwan Agriculture and Food Traceability (TAFT) program; special attention is paid to understanding the roles of the farmers’ program awareness and pesticide residue testing adoption in regard to TAFT participation. Using a national representative sample of the fruit and vegetable farmers in Taiwan, the results indicate that program awareness and pesticide residue testing adoption are the significant determinants of TAFT participation. An awareness of the government’s promotion of the TAFT program and adoption of pesticide residue testing has significantly reduced TAFT non-participation by 28.2% and 21.9% points, respectively.     

Do more bees imply higher fees? Honey bee colony strength as a determinant of almond pollination fees

Markets for pollination services have been growing in importance all over the world as pollinator populations and habitats have decreased over the last few decades (Potts et al., 2010; González-Varo et al., 2013). An early econometric analysis of pollination markets noted that honey bee colony strength in the California almond pollination market is highly variable and as such has an influence on pollination fees (Cheung, 1973). More recent economic analyses of pollination services markets have ignored the influence of colony strength on the supply and demand for pollination services. This paper provides the first econometric investigation of delivered colony strength as a determinant of almond pollination fees. I analyze the California State Beekeeper’s Association pollination fee survey responses for years 2008–2016, a total of 263 beekeeper-reported observations. I find that providing weak colonies for almond pollination results in lower fees collected by the beekeeper. By implication, beekeepers who experience high winter mortality rates likely also receive lower per-colony almond pollination fees due to low delivered colony strength. I estimate that a 10 percentage point increase in a beekeeper’s winter mortality rate leads to an average decrease of 16% in total revenues from almond pollination, a substantial overall loss given that almond pollination is a primary source of U.S. commercial beekeepers’ revenues. Additionally, I estimate that when colony strength is accounted for, payments from the Emergency Assistance for Livestock, Honey bees and Farm-Raised Fish Program in 2016 would have compensated many beekeepers for less than half of their total revenue losses in almond pollination from the corresponding 10 percentage point increase in winter mortality rates. This compensation rate is likely much lower than previously thought. This research highlights the need for additional research on the total economic impact of threats to the health of honey bee colonies, especially given the rise in recent policies enacted globally with the goal of improving honey bee health and assisting beekeeping operations.     

组织工程用三维多孔支架制备技术研究进展

综述了近几年组织工程用三维多孔支架的制备技术及研究成果,传统技术包含微球烧结法、溶液浇铸/粒子沥滤法、热致相分离/冷冻干燥法、静电纺丝法、快速成型法等;超临界技术包括超临界CO2发泡法、超临界CO2乳剂制模法、超临界CO2静电纺丝法、超临界辅助相分离法、超临界CO2溶剂去除法、离子液体聚合物混合干燥法等。重点评述了超临界流体技术在组织工程用三维支架制备中的发展前景。