Risk-optimal highway design: Methodology and case studies

Highway geometric design in mountainous areas has been a typical challenge. The combination of short horizontal curves and restricted right-of-way is a common ground for contemplating design exception in British Columbia, Canada. In practice, collision modification factors (CMFs) are advocated as quantitative measures of changes in road features on safety. However, in many situations, there are no CMFs in the literature to predict the safety impact of changing particular road features. An important example of these road features is sight distance restriction on horizontal curves. A mechanism for risk measurement has been proposed in earlier work to assist designers in comparing the safety impact of different deviations from sight distance requirements. This paper attempts to answer the questions as to whether it is possible to reduce overall risk and achieve consistency in such reduction without demanding wider right-of-way. This problem was formulated in a multi-objective optimization framework. Following this methodology, it was possible to achieve an average reduction in risk of 25% on the nine critical cross-sections. This reduction in risk was achieved without demanding wider right-of-way and without creating measurable increase in expected collision frequency due to independent re-dimensioning of different geometric elements. On theoretical grounds, this paper represents another step into the direction of developing fully probabilistic geometric design standards. On practical grounds, this paper provides an important decision mechanism that enables the efficient use of available right-of-way for new highway construction. Case studies in this paper have been applied on a major highway development in British Columba, Canada.     

Effects of source zone heterogeneity on surfactant-enhanced NAPL dissolution and resulting remediation end-points

The effectiveness of removal of nonaqueous phase liquids (NAPLs) from the entrapment source zone of the subsurface has been limited by soil heterogeneity and the inability to locate all entrapped sources. The goal of this study was to demonstrate the uncertainty of degree of source removal associated with aquifer heterogeneity. In this demonstration, source zone NAPL removal using surfactant-enhanced dissolution was considered. Model components that simulate the processes of natural dissolution in aqueous phase and surfactant-enhanced dissolution were incorporated into an existing code of contaminant transport. The dissolution modules of the simulator used previously developed Gilland-Sherwood type phenomenological models of NAPL dissolution to estimate mass transfer coefficients that are upscaleable to multidimensional flow conditions found at field sites. The model was used to simulate the mass removal from 10 NAPL entrapment zone configurations based on previously conducted two-dimensional tank experiments. These entrapment zones represent the NAPL distribution in spatially correlated random fields of aquifer hydraulic conductivity. The numerical simulations representing two-dimensional conditions show that effectiveness of mass removal depends on the aquifer heterogeneity that controls the NAPL entrapment and delivery of the surfactant to the locations of entrapped NAPLs. Flow bypassing resulting from heterogeneity and the reduction of relative permeability due to NAPL entrapment reduces the delivery efficiency of the surfactant, thus prolonging the remediation time to achieve desired end-point NAPL saturations and downstream dissolved concentrations. In some extreme cases, the injected surfactant completely bypassed the NAPL source zones. It was also found that mass depletion rates for different NAPL source configurations vary significantly. The study shows that heterogeneity result in uncertainties in the mass removal and achievable end-points that are directly related to dissolved contaminant plume development downstream of the NAPL entrapment zone.     

Determination of Hydrocarbons in Mussels from the Egyptian Red Sea Coast

Mussels (Brachidontes Sp.) collected in April 2000 from the Red Sea coastal of Egypt in order to determine the contamination by hydrocarbons. The study included 11 sampling stations covering about 450 Km of the Egyptian Red Sea coast for the first time. Total concentrations of 20 aliphatics (average 0.105 ng g(-1) of wet weight) and sixteen polycyclic aromatic hydrocarbons (PAHs) (average 5452 ng g(-1) of wet weight) were generally lower in comparison with those reported for some of the published surveillance and monitoring studies of coastal areas from various regions. These results suggest that the coastal area in the Red Sea of Egypt might be considered as a relatively unpolluted.     

(<Emphasis Type="Italic">Z</Emphasis>)-9-tricosene identified in rectal gland extracts of <Emphasis Type="Italic">Bactrocera oleae</Emphasis> males: first evidence of a male-produced female attractant in olive fruit fly

It is well-known that Bactrocera oleae (olive fruit fly) females attract conspecific males by using 1,7-dioxaspiro[5,5]undecane (1) as the main component of their sex pheromone, and that 1 is produced in the female rectal gland. Although some authors have claimed that B. oleae males also attract females, to date no male-produced female attractants have been found in this species. In this paper, we report the first identification of a substance unique to males and able to attract females. The findings of the study include the following: (1) females responded in a bioassay to hexane extracts obtained from rectal glands of 15-day-old B. oleae males, (2) the presence of (Z)-9-tricosene (2) was consistently and unambiguously identified in these extracts using gas chromatography (GC) and GC-mass spectrometry methods, (3) in preliminary bioactivity tests, low doses (equivalent to a few males) of chemically and stereoisomerically pure synthetic (Z)-9-tricosene (2) attracted olive fruit fly females. Interestingly, compound 2, commonly called muscalure, is also a well-known component of the house fly (Musca domestica) sex pheromone.     

Anti-implantation and anti-fertility potentials of Anethum graveolens L. extracts in rats

Ovarian hormones affected some enzymes in reproductive tissues. Previous studies revealed Anethum graveolens (dill) seed extract elevated ovarian hormones. In this study, we compared the effects of dill seed and leaf extracts on some enzymes activities and infertility potential. Female Wistar rats were divided into three groups of control, dill seed and dill leaf aqueous extracts treated groups. Experimental groups received 1 mL of 0.5 g kg^?1 of each extract orally for 25 days (five estrous cycles). Estradiol, progesterone, luteinizing hormone, and follicle stimulating hormone concentrations were determined. Uterus and ovaries were removed and their glucose-6-phosphate dehydrogenase, lactate dehydrogenase, and alkaline phosphatase activities were measured. Female rats of three groups were mated with untreated males. Fetuses were extracted in the 20th gestational day and their weights and crown rump lengths were measured. Anti-fertility and anti-implantation activities and fertility indices were calculated. Glucose-6-phosphate activity of dill seed treated group increased 1.6 times in the endometrium and 1.7 times in the myometrium. Progesterone concentration and lactate dehydrogenase activity of serum increased in the dill seed treated group compared to the control and dill leaf treated group. A significant decrease was observed in weights and crown rump lengths of fetuses, weights of placenta, and fertility index of the dill seed treated group compared to the control and dill leaf treated group, but its anti-implantation and anti-fertility indices increased. We suggested that high level of glucose-6-phosphate could entail increased oxidative stress in uterus and ovary. High lactate dehydrogenase activity in serum may affect cell membranes. Higher secretion of progesterone caused hormonal imbalance and produced estrous cycle irregularity. It was concluded that dill seed but not dill leaf extract could induce infertility in an animal model.     

Methane flux and oxidation at two types of intermediate landfill covers

Methane emissions were measured on two areas at a Florida (USA) landfill using the static chamber technique. Because existing literature contains few measurements of methane emissions and oxidation in intermediate cover areas, this study focused on field measurement of emissions at 15-cm-thick non-vegetated intermediate cover overlying 1-year-old waste and a 45-cm-thick vegetated intermediate cover overlying 7-year-old waste. The 45 cm thick cover can also simulate non-engineered covers associated with older closed landfills. Oxidation of the emitted methane was evaluated using stable isotope techniques. The arithmetic means of the measured fluxes were 54 and 22 g CH(4) m(-2)d(-1) from the thin cover and the thick cover, respectively. The peak flux was 596 g m(-2)d(-1) for the thin cover and 330 g m(-2)d(-1) for the thick cover. The mean percent oxidation was significantly greater (25%) at the thick cover relative to the thin cover (14%). This difference only partly accounted for the difference in emissions from the two sites. Inverse distance weighing was used to describe the spatial variation of flux emissions from each cover type. The geospatial mean flux was 21.6 g m(-2)d(-1) for the thick intermediate cover and 50.0 g m(-2)d(-1) for the thin intermediate cover. High emission zones in the thick cover were fewer and more isolated, while high emission zones in the thin cover were continuous and covered a larger area. These differences in the emission patterns suggest that different CH(4) mitigation techniques should be applied to the two areas. For the thick intermediate cover, we suggest that effective mitigation of methane emissions could be achieved by placement of individualized compost cells over high emission zones. Emissions from the thin intermediate cover, on the other hand, can be mitigated by placing a compost layer over the entire area.     

云南疣柄牛肝菌属真菌中汞含量及食用健康风险分析

汞(Hg)对人类健康有明显的毒害作用,多数野生食用菌对Hg有很强的富集能力,测定野生食用菌中总Hg含量,并对其进行食用安全评估有重要意义。采用冷原子吸收光谱法测定云南常见疣柄牛肝菌属真菌菌盖、菌柄中总汞(Hg)含量,分析样品对Hg的富集特征;以FAO/WHO现行每周Hg允许摄入量(provisional tolerable weekly intake,PTWI)标准,评估疣柄牛肝菌属真菌的食用安全性。结果显示,不同产地、种类及不同采集时间疣柄牛肝菌属真菌的总Hg含量差异明显,菌盖中总Hg含量在0.54~4.80 mg·kg-1dw之间,菌柄总Hg含量在0.32~2.80 mg·kg~(-1)dw之间,同一种牛肝菌菌盖总Hg含量均大于菌柄(Q(C/S)1),表明疣柄牛肝菌属真菌对Hg的积累量与生长环境、种类、部位等有关。根据FAO/WHO暂行的每周Hg允许摄入量标准(0.004 mg·kg-1bw),成年人(60 kg)每周食用300 g(鲜重)采自云南的疣柄牛肝菌属真菌,Hg摄入量远低于PTWI标准,对人体Hg暴露风险较低。     

Effect of dietary phytogenics (herbal mixture) supplementation on growth performance,nutrient utilization,antioxidative properties,and immune response in broilers

Environmental Science and Pollution Research - This experiment was conducted to study that effect of a phytogenics (herbal mixture) supplementation as alternative to antibiotics on the growth...     

Thermal and Flame Retardancy Behavior of Oil Palm Based Epoxy Nanocomposites

The aim of present study was to investigate the thermal properties and flame retardancy behavior of flame retardant (FR) epoxy nanocomposites from chemically treated (bromine water and tin chloride) oil palm empty fruit bunch (OPEFB) nano filler at different filler loading (1, 3, 5%). Thermal properties were evaluated through thermogravimetry analyzer, derivative thermogravimetry and differential scanning calorimetry. FR properties of nanocomposites are evaluated through UL-94 vertical burning test and limiting oxygen index (LOI). The functional group analysis of all composites was made by FTIR spectroscopy. Thermal analysis shows that degradation temperature of epoxy composites shifts from 370 to 410 °C and char yield also increases for 3% loading. Furthermore LOI value of 29% and UL-94 rating of V-0 with no flame dripping and cotton ignition, revealed that 3% oil palm nano filler filled epoxy nanocomposites display satisfactory flame retardancy. The superior flame retardancy of epoxy nanocomposites are attributed to the chemical reactions occurred in the gaseous phases and the profound synergistic flame retardation effect of tin with bromine in the treated nano OPEFB filler. All the epoxy nanocomposites displayed almost similar FTIR spectra with the characteristics metal-halogen bond supporting the synergism. Homogeneous dispersion of 3% oil palm nano filler act as highly effective combustion chain terminating agent compared with 1 and 5% nano OPEFB/epoxy nanocomposites.