Formation characteristics of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and coplanar PCBs in fly ash from a gasification–melting process of municipal solid waste

PCDDs/DF and Co-PCB (dioxin) formations were studied with ash from a newly developed gasification and melting process for municipal solid waste. Ash samples were heated in a laboratory-scale fixed-bed reactor. Emphasis was placed on the effects of the type and composition of ash, temperatures, gas residence time, and gaseous organic precursors. Investigations using macroscopic and homologue distribution analyses led to the following conclusion. The ash from the gasification–melting process had the ability to generate dioxins in flue gas. A possible carbon source is unburned carbon in the ash samples, although this was very low (less than 0.01%). An experimental result that the level of dioxins generated from preheated fly ash obtained from a conventional incinerator was much lower than that from nonheated fly ash supported this conclusion. Dioxin concentrations obviously showed temperature dependence and peaked at 350°C. Dioxins formed in a gasification–melting process ash were readily desorbed from the surface, probably because of the low carbon content of the ash. There was no experimental evidence that gaseous organic precursors fed to the reactor generated dioxins. Therefore, an organic precursor was not essential for the formation of dioxins. A good linear relationship obtained between PCDDs/DFs and gas residence time also supported the assumption. Received: February 14, 2000 / Accepted: June 30, 2000     

Special Issue: Statistical mathematics for ecological and environmental data

Environmental and Ecological Statistics -     

滨海地带地下水面与咸淡水界面伴随着潮汐波动而变化的规律的探讨研究(Ⅰ)二维数值仿真数学模型的建立及其效度的验证

在研究海岸带广泛存在的凸凹不平的不透水层的几何及地质特性的基础上,结合地下水渗流运动的特征,运用数理分析的手法,建立了不同于以往的模拟海岸带含水层咸淡水界面变动规律的二维数值仿真数学模型.其后,通过与实验数据的对比验证了其效度.     

A comparison of water solubilities by the flask and micro-column methods

A comparative examination of the two procedures of the OECD Test Guideline: Water Solubility was undertaken using carbazole, fluoranthene, anthracene, hexachlorobenzene, p-nitroaniline and diphenylamine. The flask method was modified to provide for dissolution of the solute from the surface of glass beads. By the proposed flask method, one can accurately measure the water solubility down to the order of 10 μg/L as well as those of the order of %. The micro-column method, which requires a number of concentration determinations to ensure that a saturated solution has been obtained, is recommended for the solubility range of 10 mg/L through 10 μg/L. The flask method using the procedures described in this study, covers the range of solubility above 10 μg/L with only two determinations one being a simple preliminary test and the other a precise measurement.     

Evaluation of environmentally friendly lubricant for aluminum cold forging using friction test based on spline extrusion

It is required to replace the aluminum fluoride coating, which is a popular lubricant for aluminum alloy cold forging in Japan, with environmentally friendly lubricants, because the aluminum fluoride coating has high environmental risks and needs much expense. Evaluations of lubrication performance are necessary before lubricant replacement. The authors proposed new friction test based on combined forward spline-backward can extrusion. It can realize large surface expansion, which is a characteristic of aluminum cold forging. In the present paper, a double-layer-type environmentally friendly solid lubricant film and the aluminum fluoride coating were applied to a precipitation hardened aluminum alloy. The lubrication performance was evaluated by the friction test. The double-layer-type lubricant showed superior performance enough for the replacement. The effect of surface treatment applied to workpiece on the lubrication performance was also investigated. The surface asperity generated by a wet-blasting showed high pickup resistance and low friction.     

One-step formation of oligopeptide-like molecules from Glu and Asp in hydrothermal environments

Biopolymer accumulation in the absence of enzymes is an essential step for the chemical evolution of primitive life-like systems, and successful simulation experiments of prebiotic biopolymer formation have suggested that oligopeptides could have formed near submarine hydrothermal vent environments on primitive earth. However, the yield and length of oligopeptides -- typically limited to 6-mers -- seems to be inadequate. One reason is the rapid formation of diketopiperazines (DKPs) from dipeptides. In this study, using a hydrothermal microflow reactor, we show that the one-step synthesis of oligopeptide-like molecules of length up to 20-mers proceeds from Glu and Asp. Yields of up to 0.17-0.57% were obtained in an acidic solution within 183 s at 250-310 degrees C, as evaluated by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis and different types of high-performance liquid chromatography (HPLC) analyses. The present study indicates that Glu and Asp may have played important roles in the chemical evolution of oligopeptide-like molecules in hydrothermal vent environments on primitive earth.     

Predicting leadership using nutrient requirements and dominance rank of group members

Group members must decide collectively when and where to go despite their different nutrient requirements. One mechanism underlying consensus decisions is the proposition by one individual to move. The individual frequently initiating movements is often named a “leader”, and this individual may be the most dominant, the oldest or may have the greatest physiological needs. However, high-ranking individuals are often those with the highest body mass, and thus the highest nutrient requirements. In this study, we use a state-dependent model to assess the importance of dominance and nutrient requirements to the initiation of group movements, testing different combinations of effects of these interacting factors. We first show using a theoretical approach that whatever the correlation between the dominance hierarchy and body mass, all decision-making systems are viable (or stable). However, in most cases, one individual does become the leader, and nutrient requirements appear to be more important for determining which individual will emerge as the leader than pre-existing individual characteristics such as their dominance rank. We obtained the same result when we compared the simulated distributions of initiations to the observed distributions in three macaque species. Results of our comparison of three macaque groups suggest that we can predict which group member will be the leader simply by knowing its body mass and its reproductive state. Understanding the link between dominance, needs and leadership may be a key to understanding consensus decisions and collective motion in animal groups, and might provide insight into the management of animal groups and their conservation.     

Sine-skewed axial distributions with an application for fallen tree data

An axis is an undirected line where there is no reason to distinguish one end of the line from the other. Phenomena in nature that can be described as axial data are numerous. In this paper a method of trigonometric moments for the axial normal or axial von Mises distribution as an alternative to the method by Arnold and SenGupta (Environ Ecol Stat 13:271–285, 2006) is discussed. Sine-skewed axial Jones–Pewsey, von Mises and wrapped Cauchy distributions are introduced as special cases of a more general construction of skew axial distributions. As an example the methods are applied to a data set which consists of the orientations of logs on the floor of a primeval spruce forest.     

Effects of whole spine alignment patterns on neck responses in rear end impact

Objective: The aim of this study was to investigate the whole spine alignment in automotive seated postures for both genders and the effects of the spinal alignment patterns on cervical vertebral motion in rear impact using a human finite element (FE) model.

Methods: Image data for 8 female and 7 male subjects in a seated posture acquired by an upright open magnetic resonance imaging (MRI) system were utilized. Spinal alignment was determined from the centers of the vertebrae and average spinal alignment patterns for both genders were estimated by multidimensional scaling (MDS). An occupant FE model of female average size (162 cm, 62 kg; the AF 50 size model) was developed by scaling THUMS AF 05. The average spinal alignment pattern for females was implemented in the model, and model validation was made with respect to female volunteer sled test data from rear end impacts. Thereafter, the average spinal alignment pattern for males and representative spinal alignments for all subjects were implemented in the validated female model, and additional FE simulations of the sled test were conducted to investigate effects of spinal alignment patterns on cervical vertebral motion.

Results: The estimated average spinal alignment pattern was slight kyphotic, or almost straight cervical and less-kyphotic thoracic spine for the females and lordotic cervical and more pronounced kyphotic thoracic spine for the males. The AF 50 size model with the female average spinal alignment exhibited spine straightening from upper thoracic vertebra level and showed larger intervertebral angular displacements in the cervical spine than the one with the male average spinal alignment.

Conclusions: The cervical spine alignment is continuous with the thoracic spine, and a trend of the relationship between cervical spine and thoracic spinal alignment was shown in this study. Simulation results suggested that variations in thoracic spinal alignment had a potential impact on cervical spine motion as well as cervical spinal alignment in rear end impact condition.     

Species,population and individual specific odors in urine of mole rats (Spalax ehrenbergi) detected by laboratory rats

Summary Urine odors from 4 species of blind subterranean mole rats belonging to theSpalax ehrenbergi superspecies in Israel were evaluated to determine whether there were discriminable differences in the odors that were specific to different individuals, populations, and species of mole rats. Trained laboratory rats assessed these differences in an automated olfactometer using an operant conditioning paradigm. They demonstrated the discriminability of the urine odors in the 3 categories by their correct responses in generalization trials. These characteristic species, population and individual odors may provide these solitary, territorial and blind rodents a means for diverse chemical communication in spacing behavior, reproduction, species isolation and speciation.