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361.
The Mojave Desert is characterized by hot dry summers and cold winters. The red-spotted toad (Bufo (Anaxyrus) punctatus) is the predominant anuran species; yet little is known of their thermal histories and strategies to avoid temperature extremes. We measured body temperature (T(b)) in free-ranging adult toads across all four seasons of a year using implanted data loggers. There is marked individual variation in the temperatures experienced by these toads. As expected, toads generally escape extreme seasonal and diel temperature fluctuations. However, our data demonstrate a much wider estimated T(b) range than was previously assumed. Though often for short periods, red-spotted toads do experience T(b) as low as 3.1 degrees C and as high as 39.1 degrees C. All animals showed periods of prolonged thermal stability in cooler months and wider diel oscillations in warmer months. Red-spotted toad thermal history is likely a function of site choice; the exploitation of different refuges results in diverse thermal experiences. These data represent the most complete record of thermal experiences for a desert anuran and reveal greater extremes in body temperature than previously suggested. 相似文献
362.
Material selection in manufacturing may be characterized as a series of trade-offs between characteristics, properties, environmental impacts, sustainability, availability, and economics. Societal concerns about the environmental impacts of construction practices and materials have been expressed through an increase in the demand, production and use of “green” building products. This, combined with a desire to integrate more bioproducts and natural and renewable resources into the construction industry, has extended to the production and promotion of insulation made from sheep's wool.Although substantial literature exists on the insulation properties and other benefits of wool, less is known about the economics and manufacturing processes of sheep's wool insulation at varying scales of production. This paper contributes to this field of enquiry through presentation of the preliminary results of a wool insulation manufacturing pilot project, in which the scale and economics of the production of sheep's wool insulation were considered. Processing techniques, the impact of sheep breed, yield, energy use, and manufacturing costs were also examined. The results of the pilot project indicate that, while sheep's wool insulation produced at a smaller, or artisanal scale shows some potential, scale of operation and volume of production need to be carefully considered in order to ensure long-term sustainability of the operation. Using the least expensive sheep's wool available for the manufacture of wool batt insulation (and thereby reducing production costs) did not, in this pilot study, have a negative impact on productivity or product performance. Diversion of this waste stream of currently less marketable, and consequently less valuable wool, into the production of a green building material may offer small but significant benefit to sheep producers and the broader agricultural community, as well as consumers. 相似文献
363.
A microcosm study was conducted to evaluate the need for bioaugmentation after a thermal treatment to anaerobically dechlorinate trichloroethene (TCE) to ethene. The microcosms were either: heated to 100 degrees C and slowly cooled to simulate thermal remediation while bioaugmenting when the declining temperature reached 10 degrees C; or kept at ambient groundwater temperatures (10 degrees C) and bioaugmented for comparison. Aquifer samples from three sediment locations within a TCE-polluted source zone were investigated in duplicate microcosms. In biostimulated (5 mM lactate) and heated microcosms, no conversion of TCE was observed in 4 out of 6 microcosms, and in the remaining microcosms the dechlorination of TCE was incomplete to cDCE (cis-dichloroethene). By comparison, complete TCE dechlorination to ethene was observed in 4 out of 6 heated microcosms that were bioaugmented with a highly enriched dechlorinating mixed culture, KB-1, but no electron donor, and also in 4 of 6 microcosms that were augmented with KB-1 and an electron donor (5 mM lactate). These data suggest that electron donor released during heating, was capable of promoting complete dechlorination coincident with bioaugmentation. Heated microcosms demonstrated less methanogenesis than unheated microcosms, even with elevated H2 concentrations and addition of KB-1, which contains methanogens. This suggests that the heating process suppressed the native microbial community, which can decrease competition with the bioaugmented culture and increase the effectiveness of dechlorination following a thermal treatment. Specifically, cDCE removal rates were four to six times higher in heated than unheated bioaugmented microcosms. This study confirms the need for bioaugmentation following a laboratory thermal treatment to obtain complete dechlorination of TCE. 相似文献
364.
365.
选取苯系物中的代表性组分苯、甲苯和二甲苯等化合物,通过热脱附、气相色谱质谱条件的优化及方法学考察,建立了热脱附进样-气相色谱-同位素比值质谱(GC-C-IRMS)测定苯系物单体碳同位素比值的方法。结果表明,单体化合物进样量在0.3μg以上均能满足测定要求;与直接进样方式相比,热脱附进样对单体碳同位素比值测定无分馏影响;标准溶液和苯系物土壤样品测定结果的RSD分别为1.0%~1.7%和0.3%~2.6%。 相似文献
366.
367.
Analytical reagents identify and manage metal pollution, a major environmental issue. Regrettably, these compounds' safety concerns, especially when heated, have been neglected. This research examines the thermal hazard of the extremely reactive analytical reagent styphnic acid. Differential scanning calorimetry, thermogravimetric analysis, and accelerating rate calorimetry examined styphnic acid's thermodynamics. Thermogravimetric analysis showed weight loss reactions starting at 127 °C and peaking at 208 °C. Differential scanning calorimetry showed an endothermic peak at 176 °C. The accelerating rate calorimetry test showed that styphnic acid self-accelerates at 237 °C after 196.5 °C. Kissinger, Ozawa-Flynn-Wall, and Kissinger-Akahira-Sunose thermokinetic models calculated apparent activation energy from 131.677 to 155.718 kJ/mol. A nonlinear regression analysis showed that styphnic acid undergoes a two-step autocatalytic reaction during heat degradation. Thermal safety was assessed by measuring time to conversion limit, maximum rate, total energy release, self-accelerating decomposition temperature, and adiabatic temperature rise. Styphnic acid is less stable at higher temperatures and its thermal hazards depend on heating rate. The computed SADT was 109.04 °C, with alarm and control temperatures of 104.04 and 99.04 °C, respectively. The risk matrix analysis based on Tad and TMRad suggests reducing thermal instability. This study on styphnic acid's thermal risks and safe storage and transit during analytical applications is beneficial. 相似文献
368.
古商业街木结构建筑较多,防火间距先天不足,发生火灾后蔓延迅速,有必要开展木结构建筑引燃特性研究以获得合理的防火间距设置参数.以古商业街为研究对象,以临界温度和热辐射强度作为着火建筑对面木结构建筑被引燃的判定指标,综合考虑环境风速、建筑间距、火源功率、喷淋系统等因素,运用火灾动力学模拟软件FDS分析系列火灾场景下的温度和... 相似文献