无公害食用菌生产技术规程的制定研究

通过分析近年来我国食用菌生产管理和产品质量安全存在的问题,论述了开展无公害食用菌生产的重要性.同时吸收各地的生产经验.根据国家有关标准,从食用菌生产场所的选择、培养基材料和水的要求、栽培管理、病虫害防治、采后处理、加工贮藏和产品质量安全检测等几个方面,提出了一整套较系统的无公害食用菌生产技术操作规程.该项技术规程在生产上的推广应用,对提高食用菌生产技术水平、改善和保障食用菌产品质量、增强产品在国际市场的竞争力将产生积极的推动作用.     

利用稳定同位素技术研究外源物质输入对太湖微食物链的贡献

应用碳氮稳定同位素方法研究了太湖不同营养状态湖区内外源物质对微生物食物链主要成分的贡献.结果表明,在有大量外来物质输入的河口区,细菌、浮游枝角类、溶解性有机物(DOM)和颗粒性有机物 (POM)的δ¹³Ｃ 和δ¹⁵Ｎ同位素值,溶解性无机碳(DIC)的δ¹³Ｃ同位素值明显低于其它采样点,这表明河口区受陆源营养物质的影响强烈.其中,DOM的δ¹³Ｃ平均值和陆源C₃植物的δ¹³Ｃ值-26‰相近,表现出流域外源的排入对湖泊碳库的影响.与从DIC到浮游藻类的分馏值22‰计算得到的浮游藻类δ¹³Ｃ值相比,POM主要为内源藻类贡献.浮游枝角类的δ¹³Ｃ的平均值低于POM (0.2‰)和细菌 (2.5‰),这可能是由于枝角类脂类的积聚或选择性的摄食δ¹³Ｃ较为贫化的微型藻类(<50 μm)造成的.根据双组分混合模型(two-member mixing model),在河口区陆源C对细菌生物量的贡献占到61.2%,随着向湖心的推进,内源藻类的贡献逐渐增加(58.5%～92.9%).     

Determination of polycyclic aromatic hydrocarbons in dry tea

Twenty-eight different tea samples sold in the United States were evaluated using high-performance liquid chromatography (HPLC) with fluorescence detection (FLD) for their contamination with polycyclic aromatic hydrocarbons (PAHs). Many PAHs exhibit carcinogenic, mutagenic, and teratogenic properties and have been related to several kinds of cancer in man and experimental animals. The presence of PAHs in environmental samples such as water, sediments, and particulate air has been extensively studied, but food samples have received little attention. Eighteen PAHs congeners were analyzed, with percentage recovery higher than 85%. Contamination expressed as the sum of the 18 analyzed PAHs was between 101 and 1337 μg/kg on dry mass and the average contents in all of the 28 examined samples was 300 μg/kg on dry mass. Seven of the congeners were found in all samples with wide ranges of concentrations as follows: fluorene (7–48 μg/kg), anthracene (1–31 μg/kg), pyrene (1–970 μg/kg), benzo(a)anthracene (1–18 μg/kg) chrysene (17–365 μg/kg), benzo(a)pyrene (1–29 μg/kg), and indeno(1,2,3-cd)pyrene (4–119 μg/kg). The two most toxic congeners benzo(a)pyrene and dibenzo(a,h)anthracene were found at high concentrations only in Earl Grey Twinnings, Earl Grey Harney& Sons Fine Teas, and Chai Ultra Spice Black Tea Twinnings. Six PAH congeners are considered as suspected carcinogens (U.S.EPA), formed the basis of the estimation of the toxic equivalent (TEQ), Chai Ultra-Spice Black Tea Twinnings had the highest TEQ (110.9) followed by two grey tea samples, Earl Grey Harney & Sons Fine Tea (57.7) and Earl Grey Twinnings (54.5). Decaffeinated grey teas had the lowest TEQs, decaffeinated Earl Grey Bigelow (9.4) and Green Tea Honey Lemon Decaffeinated Lipton (9.6).     

Results of the monitoring program of pesticide residues in organic food of plant origin in Lombardy (Italy)

Organic agriculture, with its restrictions on the use of synthetic chemical inputs, seems to offer a low-residue alternative to conventional methods. In Europe, the Council Regulation n. 2092/91/EEC regulates the production and trade of organic products and foodstuffs; national and regional legislation in Italy gives specific guidance on the surveillance of organic agriculture. However, monitoring of specific chemical residues in organic foodstuffs is part of the regular controls on food, aiming to safeguard consumer's health. Monitoring programs are coordinated at the national level by the Ministry of Health and at local level by Regional authorities. In Lombardy, in accordance with the provisions of the General Directorate of Health of the Region and under the supervision of the 15 Local Health Units, a monitoring program of pesticide residues in food of plant origin is undertaken every year. The International Centre for Pesticides and Health Risk Prevention (ICPS), on behalf of the General Directorate of Health of the Region of Lombardy, has been collecting and elaborating the data resulting from the analysis of food samples, carried out by the local laboratories. During the period 2002–2005, a total of 3508 samples food of plant origin were analyzed for pesticide residues, among which were 266 samples of organic farming products. Commodities were classified into groups (citrus fruits, legumes, vegetables, potatoes, processed products, cereals, and fruit other than citrus) and the outcomes of the analyses were reported by year, origin of the sample and presence/absence of pesticide residues. Results showed that the vast majority of organic farming products were in conformity with the relevant legislation and did not contain detectable pesticide residues. A limited amount of samples had residues at concentration below the Maximum Residue Limit (MRL). Only in one sample the residue level was above the MRL, however it did not pose a concern for public health, as demonstrated by the outcomes of dietary risk assessment. Organic fruits and vegetables can be expected to contain fewer agrochemical residues than conventionally grown alternatives. There is a widespread belief that organic agriculture products are safer and healthier than conventional foods. It is difficult to come to conclusions, but what should be made clear to the consumer is that “organic” does not automatically equal “safe”. In the absence of adequate comparative data, additional studies in this area of research are required.     

Trophic Flexibility and the Persistence of Understory Birds in Intensively Logged Rainforest

Effects of logging on species composition in tropical rainforests are well known but may fail to reveal key changes in species interactions. We used nitrogen stable‐isotope analysis of 73 species of understory birds to quantify trophic responses to repeated intensive logging of rainforest in northern Borneo and to test 4 hypotheses: logging has significant effects on trophic positions and trophic‐niche widths of species, and the persistence of species in degraded forest is related to their trophic positions and trophic‐niche widths in primary forest. Species fed from higher up the food chain and had narrower trophic‐niche widths in degraded forest. Species with narrow trophic‐niche widths in primary forest were less likely to persist after logging, a result that indicates a higher vulnerability of dietary specialists to local extinction following habitat disturbance. Persistence of species in degraded forest was not related to a species’ trophic position. These results indicate changes in trophic organization that were not apparent from changes in species composition and highlight the importance of focusing on trophic flexibility over the prevailing emphasis on membership of static feeding guilds. Our results thus support the notion that alterations to trophic organization and interactions within tropical forests may be a pervasive and functionally important hidden effect of forest degradation. Flexibilidad Trófica y la Persistencia de Aves de Sotobosque en un Bosque Lluvioso Talado Intensivamente     

基于直觉模糊距离法的堰塞湖减灾方案选优

针对堰塞湖减灾群决策信息的不确定性与模糊性,为解决不完全信息条件下属性指标及专家之间存在的相互关联群决策问题,综合运用直觉模糊集理论、海明距离原理和熵权理论,将直觉模糊距离群决策方法运用到堰塞湖减灾决策过程中。工程实例研究表明,运用直觉模糊距离法决策出的最优方案具有较高的区分度和敏感性,增强了决策的客观性、科学性,能为堰塞湖减灾决策提供更为可靠的依据,具有较强的实用价值。     

The dynamic response of pressure relief valves in vapor or gas service,part I: Mathematical model

In order to prevent unstable operation, or “chatter”, of a pressure relief the API guidelines recommend limiting the irreversible pressure loss in the inlet line to a pressure relief valve to no more than 3% of the valve set pressure. This criterion is based on steady-state operating conditions and a typical blow-down pressure for the valve of about 7% of the set pressure. However, the stability of the valve is also influenced by other factors such as the dynamic response of the valve disk to the unsteady pressures and forces exerted by the fluid on the disk. A model for the opening lift dynamic response of a pressure relief valve in gas/vapor service is presented here which accounts for all of these effects through a set of five coupled nonlinear algebraic/differential equations. These equations are solved by a numerical method that can be implemented on a spreadsheet to predict the position of the valve disk as a function of time for given valve characteristics, operating conditions, and installation parameters. The model incorporates the influence of the various parameters on the stable/unstable nature of the disk response. An example is presented for a typical valve that illustrates the various modes of stable and unstable dynamic response that can be predicted by the model under various conditions. Two additional papers will be forthcoming: Part II – Experimental Investigation and Part III – Analysis of Data and Comparison with Model Predictions.     

Impact of global warming on agricultural product markets: stochastic world food model analysis

Climatic change through global warming and drought is a major issue for agricultural production. Most researchers who discuss the effects of such changes on agriculture report estimated yield changes based on crop process models. However, studies focusing on the impact of climatic change on agricultural product markets are very rare. This paper examines the relationship between climatic change and world food markets, i.e., the supply and demand of crops, by using a stochastic version of a world food model, the International Food and Agricultural Policy Simulation Model. The results suggest that variations in the production of maize and soybeans in some major producing countries will be large, and variations in the producer prices of all crops will increase. Countries that suffer higher price risk because of high sensitivity to temperature fluctuations may need to consider changes in cropping patterns.     

固含率和稀释率对餐厨垃圾水解酸化过程的影响研究

研究了餐厨垃圾分批厌氧消解过程中不同起始固含率（10％,12％和14％）和稀释率（0.25 d^－1和0.33 d^－1）对水解酸化过程pH值、垃圾消解、水解酸化液生产效率、脂肪酸组成和浓度等的影响。实验结果发现：以总固体去除率、单位质量垃圾累积COD溶出量（ACODm）和单位体积反应器累积COD溶出量（ACODv）等指标作为评价标准,起始固含率12％的体系具有较高的垃圾处理效率和反应器运行效率。与稀释率0.25 d^－1的体系相比,稀释率0.33 d^－1的体系在pH稳定性、总固体去除率和水解酸化液生产效率等方面具有明显的优势。所有体系中水解酸化产生的脂肪酸和醇均以乙酸、乙醇和丁酸为主,丙酸占总脂肪酸和醇的百分数在14.6％到17.1％之间,这种脂肪酸组成不会发生丙酸抑制,有利于后续产甲烷发酵的进行。     

餐厨垃圾的高温厌氧消化处理研究

在55℃条件下,研究了餐厨垃圾高温厌氧消化过程中pH、VFA、总磷、产气量以及COD、TS和VS的变化,结果表明：在消化过程中pH先下降后上升,总VFA浓度增大,而其中游离态VFA浓度先增大后减少。消化过程总产气量为43 211 mL,整个过程消耗TS的平均产气率为158.98 mL/g TS,COD去除率为38.76％,总磷去除率达到98.87％,底物TS和VS去除率分别31.71％和50.24％。经过厌氧消化处理,沼渣中不含对人体和许多动物有害的沙门氏菌、痢疾杆菌、大肠杆菌及粪大肠杆菌,而富含有机质、氮、磷和钾等的营养物质和芽孢杆菌、防线菌等有益菌种。