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排序方式: 共有1850条查询结果,搜索用时 218 毫秒
961.
Shuai Zhang Aimin Xiang Huafeng Tian A.Varada Rajulu 《Journal of Polymers and the Environment》2018,26(1):15-22
To decrease the usage of petroleum based materials, a kind of bio-resource based composite foams were developed with soy protein isolate (SPI) as reactive reinforcing filler in castor oil based polyurethane foams (PUF) prepared by self-rising method using water as a blowing agent. The resulting composite foams were evaluated for their morphology, density, mechanical and biodegradation properties, etc. Fourier transform infrared spectroscopy study exhibited characteristic peaks for SPI and PUF and indicated that the amino groups and hydroxyl groups on SPI reacted with polyphenyl polymethylene polyisocyanates (PAPI) to increase the crosslinking degrees of the composite foams. Densities of the resultant composites were found to increase with increasing SPI content. Mechanical properties of the samples were improved with the increase of SPI content. The compost tests further proved that the composite PUF had better biodegradability than neat PUF. Therefore, this research has provided a simple method of preparing the bio-resource based polyurethane foams, while exploring the potential of using SPI in polyurethane foam applications. 相似文献
962.
Acid treated multiwalled carbon nanotubes (MWNTs) were incorporated into glycerol plasticized soy protein to form MWNTs/soy protein nanocomposite plastics. The influence of the polar groups grafted on carbon nanotubes by acid treatment on the compatibility would be studied. The results showed that aggregation of carbon nanotubes was reduced by acid treatment and some polar groups were grafted on the nanotubes. The modified MWNTs were dispersed in soy protein matrix homogeneously and exhibited good compatibility with soy protein matrix. The crystalline structure of soy protein was not changed by MWNTs. The mechanical properties were dramatically enhanced through MWNTs incorporation due to the strong hydrogen bonding between them and the homogeneously dispersion of MWNTs in protein matrix, indicating the reinforcing effect of MWNTs in soy protein matrix. The water uptake was reduced and the thermal stability was enhanced by MWNTs incorporation. 相似文献
963.
为进一步探索啶酰菌胺对水生生物的毒性,选择斑马鱼为供试生物,采用半静态法,研究了啶酰菌胺在斑马鱼体内的富集与消除规律及对其肝脏和鳃的毒性作用。结果表明,斑马鱼暴露于0.08、0.32 mg·L~(-1)中,14 d后均达到富集平衡,28 d生物富集系数(BCF_(28 d))分别为35.50和36.72。在0.16、0.32 mg·L~(-1)浓度下,斑马鱼的比肝重(HSI)和比鳃重(BSI)均明显高于对照组,而肝脏和鳃中琥珀酸脱氢酶(SDH)和线粒体呼吸链复合物II活性均明显低于对照组,浓度低于0.08 mg·L~(-1)时,对斑马鱼无明显影响。由此可知,啶酰菌胺对斑马鱼为中等富集性,并对其肝脏和鳃有一定毒性作用。 相似文献
964.
通过室内微宇宙实验系统研究了天津厚蟹(Helice tientsinensis)和双齿围沙蚕(Perinereis aibuhitensis)生物扰动作用下河口沉积物中荧蒽的去除情况。实验结果显示,天津厚蟹扰动组中荧蒽的去除率显著高于沙蚕扰动组(P=0.05)和对照组(P=0.003),其中对表层(0~2 cm)和中层(3~5 cm)的促进效果最为显著;虽然各实验组表层沉积物中荧蒽的去除率均超过50%,但扰动组的去除更快,在36 d时就达最高去除率68%;双齿围沙蚕扰动组底层沉积物中荧蒽的去除率高于厚蟹扰动组和对照组,但差异不显著。研究表明表层沉积物中的荧蒽易去除,厚蟹生物扰动对荧蒽去除有显著促进作用;在距离表层5cm以下的沉积物中荧蒽的持久性增强,但生物扰动作用可促进其去除。 相似文献
965.
Yulun Nie Xike Tian Zhaoxin Zhou Yu-You Li 《Frontiers of Environmental Science & Engineering》2017,11(6):6
The effects of food to microorganism (F/M) ratio and alcohol ethoxylate (AE) dosage on the methane production potential were investigated in treatment of low-strength wastewater by a submerged anaerobic membrane bioreactor (SAnMBR). The fate of AE and its acute and/or chronic impact on the anaerobic microbes were also analyzed. The results indicated that AE had an inhibitory effect to methane production potential (lag-time depends on the AE dosage) and the negative effect attenuated subsequently and methane production could recover at F/M ratio of 0.088–0.357. VFA measurement proved that AE was degraded into small molecular organic acids and then converted into methane at lower F/M ratio (F/M<0.158). After long-term acclimation, anaerobic microbe could cope with the stress of AE by producing more EPS (extracellular polymeric substances) and SMP (soluble microbial products) due to its self-protection behavior and then enhance its tolerance ability. However, the methane production potential was considerably decreased when AE was present in wastewater at a higher F/M ratio of 1.054. Higher AE amount and F/M ratio may destroy the cell structure of microbe, which lead to the decrease of methane production activity of sludge and methane production potential. 相似文献
966.
967.
968.
969.
Pu R Gong P Tian Y Miao X Carruthers RI Anderson GL 《Environmental monitoring and assessment》2008,140(1-3):15-32
For monitoring and controlling the extent and intensity of an invasive species, a direct multi-date image classification method
was applied in invasive species (salt cedar) change detection in the study area of Lovelock, Nevada. With multidate Compact
Airborne Spectrographic Imager (CASI) hyperspectral data sets, two types of hyperspectral CASI input data and two classifiers
have been examined and compared for mapping and monitoring the salt cedar change. The two types of input data are all two-date
original CASI bands and 12 principal component images (PCs) derived from the two-date CASI images. The two classifiers are
an artificial neural network (ANN) and linear discriminant analysis (LDA). The experimental results indicate that (1) the
direct multitemporal image classification method applied in land cover change detection is feasible either with original CASI
bands or PCs, but a better accuracy was obtained from the CASI PCA transformed data; (2) with the same inputs of 12 PCs, the
ANN outperforms the LDA due to the ANN’s non-linear property and ability of handling data without a prerequisite of a certain
distribution of the analysis data. 相似文献
970.
Assessment of sampling designs to measure riverine fluxes from the Pearl River Delta, China to the South China Sea 总被引:1,自引:0,他引:1
Ni HG Lu FH Luo XL Tian HY Wang JZ Guan YF Chen SJ Luo XJ Zeng EY 《Environmental monitoring and assessment》2008,143(1-3):291-301
The Pearl River Delta (PRD), located in South China and adjacent to the South China Sea, is comprised of a complicated hydrological system; therefore, it was a great challenge to sample adequately to measure fluxes of organic and inorganic materials to the coastal ocean. In this study, several sampling designs, including five-point (the number of sampling points along the river cross-section and three samples collected at the upper, middle, and bottom parts at each vertical line), three-point (at the middle and two other profiles), one-point (at the middle profile), and single-point (upper, middle, or bottom sub-sampling point at the middle profile) methods, were assessed using total organic carbon (TOC) and suspended particulate matter (SPM) as the measurables. Statistical analysis showed that the three- and five-point designs were consistent with one another for TOC measurements (p > 0.05). The three- and one-point sampling methods also yielded similar TOC results (95% of the differences within 10%). Single-point sampling yielded considerably larger errors than the three- and one-point designs, relative to the results from the five-point design, but sampling at the middle sub-point from the middle profile of a river achieved a relatively smaller error than sampling at the upper or bottom sub-point. Comparison of the sampling frequencies of 12 times a year, four times a year, and twice a year indicated that the frequency of twice a year was sufficient to acquire representative TOC data, but larger sample size and higher sampling frequency were deemed necessary to characterize SPM. 相似文献