Improved oxidative stability of biodiesel via alternative processing methods using cottonseed oil

Biodiesel from waste cooking oil (WCO) requires antioxidants to meet oxidation stability specifications set forth in ASTM D6751 or EN 14214. In contrast, unrefined cottonseed oil (CSO), containing tocopherols and gossypol, produces biodiesel of higher oxidation stability. However, only a portion of these CSO endogenous antioxidants are suspected to be retained in biodiesel. Because the economics of biodiesel manufacturing rely upon inexpensive sources of triglycerides, emphasis was placed on developing improved alternative processing methods where WCO was the main source of methyl esters (WCOME) and CSO was used as a supplemental source of triglycerides and antioxidants in a 4:1 ratio. This study compared four processing methods for their ability to produce biodiesel of increased oxidative stability prepared from a 4:1 ratio of WCO:CSO. Two novel processing methods developed for this study utilise solvent properties of fatty acid methyl esters and glycerol to avoid additional chemical inventory for biodiesel processors. This study concludes that the two new processing methods resulted in biodiesel that had statistically significant improved oxidation stability when compared to two common industrial processing methods. Another significant finding is that high-shear homogenisation during transesterification reduced reaction time from the published one hour to 16 minutes.     

海洋石油污染监测(艹屈)标准物质的研制

介绍了[艹屈]标准物质的研究、制备方法,进行了均匀性检验、稳定性检验,统计计算了检验结果。结果表明,该标准物质的均匀性和稳定性良好,在5a内有效,标准物质符合国家标准,可用于海洋环境监测。     

Purpose-Driven Public Sector Reform: The Need for Within-Government Capacity Build for the Management of Slope Stability in Communities in the Caribbean

This article stresses the importance of within-government capacity build as the optimal approach to minimizing landslide risk to the most vulnerable communities in the developing world. Landslide risk is an integrated issue that demands strong managerial leadership and multidisciplinary inclusion to develop structures that deliver sustainable improvements in the reduction of risk. The tension between projects demanding international technical and financial intervention and those capable of “within-country” solutions are examined. More particularly, the challenges of developing a management methodology capable of energizing inter-ministry collaboration to achieve community-level action is examined in the context of a recently established program of slope stability management in St. Lucia. The program, Management of Slope Stability in Communities (MoSSaiC), is shown to have successfully fostered not only extensive technical collaboration within government but also to have energized local communities in the shared mission of capacity build through their direct involvement in the management process.     

巢湖内源磷释放特点、稳定性及化学控制研究

以巢湖内源磷负荷为研究对象,通过实验室模拟,探讨了巢湖内源磷释放过程上覆水中ρ(总磷)和ρ(铁)之间的关系,重点研究了pH和溶解氧对内源磷释放的影响,并对实验前后沉积物中各形态内源磷的含量进行比较.结果表明:上覆水中ρ(总磷)与ρ(铁)呈正线性相关;pH相同时,厌氧条件下内源磷的释放量约是好氧条件的9.16倍;无论是好氧还是厌氧条件,内源磷的释放量均是碱性条件最大,酸性次之,中性最小;铝磷、铁磷的释放量随pH增大而增大;在酸性条件下,钙磷是内源磷释放的主要来源.最后讨论了氯化铝和氯化铁控制磷负荷的作用.      

某尾矿库安全分析及治理对策

通过现场安全检查和防洪、渗流、抗滑计算,对广东石人嶂钨矿梅子窝2号尾矿库的事故隐患进行了辨识,给出了该尾矿库的安全度;针对该尾矿库存在的安全问题及面临闭库的实际状况,提出了以拦截库外洪水、重整库内坡度及进行坡面维护为主的安全治理对策.     

水成膜泡沫对变压器油池火的窒息特性研究

水成膜泡沫在油类表面的窒息作用是扑灭油类火灾的重要机理之一,针对自行开发的快速型泡沫灭火剂开展了其对油池火的窒息灭火特性研究。首先通过老化试验测试了泡沫液的热稳定性,然后对比了不同成分泡沫液在25#变压器油表面的铺展特性,之后研究了不同发泡倍率和成分的泡沫液对油池火的窒息灭火效果及影响规律。研究发现,铺展性能不佳的泡沫液会逐渐丧失窒息能力,而铺展性能优异的泡沫液能持续发挥窒息作用。提升泡沫液热稳定性有利于在油面形成稳定的液膜,隔绝氧气并降低可燃分子挥发速率。此外,发泡倍率较低的泡沫液的流动性更强,在相同液体流量条件下低倍数泡沫的窒息灭火效果更优。自研的快速型泡沫灭火剂在热稳定性和铺展性能两方面均具备优良的性能,因此其窒息灭火效率和抗复燃能力优于现有的大部分同类泡沫灭火剂。     

原有路基稳定性对高速公路加宽工程的影响分析

通过数值模拟,结合高速公路加宽工程实例,分析了在原有路基未固结稳定情况下新老路基的固结沉降变形特性,并对可能的处理方法进行了分析探讨。结果表明,新老路基的沉降随着老路固结度的减小而逐渐增大,但差异沉降却逐渐减小;当老路固结度较小时,在固结后期差异沉降可能逐渐减小;轻质路堤法和复合地基法分别处理新路地基时,各有优缺点,轻质路堤法对老路附加沉降影响较大,但能较好地控制不均匀沉降,复合地基法对老路附加沉降影响很小,但在老路固结度较低时,差异沉降较大。     

地震对边斜坡稳定性的影响研究

地震作为一种突发式的自然灾害,对边斜坡稳定性的影响是显著的,因此研究边斜坡稳定性在地震动力作用下的变形、破坏具有重要的理论和现实意义.笔者在总结了地震边斜坡稳定性常用的分析方法的基础上.提出了刚体极限平衡法中地震力的确定方法及考虑地震力作用的计算模式,为地震边斜坡的稳定性评价提供了途径,为该类项目防治工程设计提供了科学的依据,值得同类工程借鉴和推广.     

Investigation of exhaled pollutant distribution in the breathing microenvironment in a displacement ventilated room with indoor air stability conditions

This study experimentally studied the dispersion of exhaled pollutant in the breathing microenvironment (BM) in a room equipped with a displacement ventilation (DV) system and indoor air stability conditions (i.e., stable and unstable conditions). The vertical temperature differences and the carbon dioxide (CO₂) concentration in the BM were measured. Results show that when DV is combined with the stable condition (DS), pollutant tends to accumulate in the BM, leading to a high pollutant concentration in this region. Whereas, when DV is combined with the unstable condition (DU), pollutant diffuses to a relatively wider area beyond the BM, thus the pollutant concentration in the BM is substantially reduced. Moreover, increasing the flow rate can reduce the pollutant concentration in the BM of the DS but yields little difference of the DU. In addition, personal exposure intensity increases with time, and the DS has a relatively higher increase rate than DU. The results suggest that indoor air stability will affect the performance of DV systems. DS will lead to a higher health risk for people when they stay in the indoor environment with pollutant sources, and DU is recommended for minimizing pollutant level in the BM in order to reduce the pollutant concentration and providing better air environments for the occupants.     

Structural changes in lake functioning induced from nutrient loading and climate variability

Climate variability is increasingly recognized as an important regulatory factor, capable of influencing the structural properties of aquatic ecosystems. Lakes appear to be particularly sensitive to the ecological impacts of climate variability, and several long time series have shown a close coupling between climate, lake thermal properties and individual organism physiology, population abundance, community structure, and food web dynamics. Thus, understanding the complex interplay among meteorological forcing, hydrological variability, and ecosystem functioning is essential for improving the credibility of model-based water resources/fisheries management. Our objective herein is to examine the relative importance of the ecological mechanisms underlying plankton seasonal variability in Lake Washington, Washington State (USA), over a 35-year period (1964–1998). Our analysis is founded upon an intermediate complexity plankton model that is used to reproduce the limiting nutrient (phosphate)–phytoplankton–zooplankton–detritus (particulate phosphorus) dynamics in the lake. Model parameterization is based on a Bayesian calibration scheme that offers insights into the degree of information the data contain about model inputs and allows obtaining predictions along with uncertainty bounds for modeled output variables. The model accurately reproduces the key seasonal planktonic patterns in Lake Washington and provides realistic estimates of predictive uncertainty for water quality variables of environmental management interest. A principal component analysis of the annual estimates of the underlying ecological processes highlighted the significant role of the phosphorus recycling stemming from the zooplankton excretion on the planktonic food web variability. We also identified a moderately significant signature of the local climatic conditions (air temperature) on phytoplankton growth (r = 0.41), herbivorous grazing (r = 0.38), and detritus mineralization (r = 0.39). Our study seeks linkages with the conceptual food web model proposed by Hampton et al. [Hampton, S.E., Scheuerell, M.D., Schindler, D.E., 2006b. Coalescence in the Lake Washington story: interaction strengths in a planktonic food web. Limnol. Oceanogr. 51, 2042–2051.] to emphasize the “bottom-up” control of the Lake Washington plankton phenology. The posterior predictive distributions of the plankton model are also used to assess the exceedance frequency and confidence of compliance with total phosphorus (15 μg L⁻¹) and chlorophyll a (4 μg L⁻¹) threshold levels during the summer-stratified period in Lake Washington. Finally, we conclude by underscoring the importance of explicitly acknowledging the uncertainty in ecological forecasts to the management of freshwater ecosystems under a changing global environment.