A series of form-stable phase change materials （FSPCMs） comprising paraffin as the latent heat storage material, diurea as the supporting material and base oil as the performance improvement agent were prepared. The...A series of form-stable phase change materials （FSPCMs） comprising paraffin as the latent heat storage material, diurea as the supporting material and base oil as the performance improvement agent were prepared. The diurea was synthesized in the system of paraffin/oil directly. A series of characterization was carried out for a deep understand- ing of shape stability and material properties of diurea-FSPCMs. The results showed that paraffin and base oil were packaged in the three-dimensional supra-molecular structures network which was formed by diurea. The dropping point of the prepared FSPCMs could reach 256 ℃ and the oil separation rate was as low as 1.19% at 100 ℃ for 30 h. The results of thermal properties tests showed that the prepared FSPCMs exhibited excellent thermal stability and the FSPCMs remained solid-like state in the temperature range from 25 to 200 ℃. This study proposes a novel method to prepare high-temperature non-flowing FSPCMs composites and methods to detect the thermal stability and shape stability of FSPCMs, which is helpful in understanding the shape stability mechanism and broadening the potential application of FSPCMs.展开更多
运用文献计量学的方法,对1986—2016年科学引文索引扩展版(SCI-E)中收录的有关"臭氧和乙烯叉二脲(EDU)"的文章进行文献类型、研究学科方向、年度发文量、作者、国家或地区、研究机构、来源出版物名称、基金资助机构分析,并对...运用文献计量学的方法,对1986—2016年科学引文索引扩展版(SCI-E)中收录的有关"臭氧和乙烯叉二脲(EDU)"的文章进行文献类型、研究学科方向、年度发文量、作者、国家或地区、研究机构、来源出版物名称、基金资助机构分析,并对研究重点、研究中采用的臭氧浓度、臭氧处理方式、EDU施用浓度、EDU施用部位、所选用的植物材料等进行了统计。结果表明,学科方向以生态环境科学为主;文献数量在年际间呈波动状态,2015年发表文献数量最多;Manning W J在此方向发表论文数量居于首位;美国、印度、意大利等国对该领域比较重视;《环境污染》期刊上发表的相关研究论文数量最多;目前,EDU对臭氧胁迫下农作物产量、植物可见伤害及植物光合作用变化情况较受关注。今后应加大EDU缓解臭氧伤害的分子机理及植物施用EDU后毒物学方面的研究。展开更多
Soil microbial activity is recognized as an important factor affecting nitrogen (N) release from slow-release fertilizers. However,studies on the effect of size and activity of soil microflora on fertilizer degradatio...Soil microbial activity is recognized as an important factor affecting nitrogen (N) release from slow-release fertilizers. However,studies on the effect of size and activity of soil microflora on fertilizer degradation have provided contrasting results. To date, no clear relationships exist between soil microbial activity and the release of N from slow-release fertilizers. Hence, the aim of this study was to better understand such relationships by determining the release of N from three slow-release fertilizers in soils with different microbial activities. Soils were amended with urea-formaldehyde (UF), isobutylidene diurea (IBDU), and crotonylidene diurea (CDU). Urea, a soluble fertilizer, was used as the control. Fertilized soil samples were placed in a leaching system, and the release of N was determined by measuring ammonium-N and nitrate-N concentrations in leachates during 90 d of incubation. Non-linear regression was used to fit N leaching rate to a first-order model. In all the treated soils, N was released in the order: urea (89%–100%) > IBDU (59%–94%) >UF (46%–73%) > CDU (44%–56%). At the end of incubation, N released from CDU did not differ (P > 0.05) among soils. On the contrary, UF and IBDU released significantly lower (P < 0.05) amounts of N in the soil with higher microbial activity and lower pH.The rate constant (K_0) for UF was lower (P < 0.05) in the soil with lower pH. Taken together, our results indicated that soil microbial size and microbial activity had a marginal effect on fertilizer mineralization.展开更多
文摘A series of form-stable phase change materials （FSPCMs） comprising paraffin as the latent heat storage material, diurea as the supporting material and base oil as the performance improvement agent were prepared. The diurea was synthesized in the system of paraffin/oil directly. A series of characterization was carried out for a deep understand- ing of shape stability and material properties of diurea-FSPCMs. The results showed that paraffin and base oil were packaged in the three-dimensional supra-molecular structures network which was formed by diurea. The dropping point of the prepared FSPCMs could reach 256 ℃ and the oil separation rate was as low as 1.19% at 100 ℃ for 30 h. The results of thermal properties tests showed that the prepared FSPCMs exhibited excellent thermal stability and the FSPCMs remained solid-like state in the temperature range from 25 to 200 ℃. This study proposes a novel method to prepare high-temperature non-flowing FSPCMs composites and methods to detect the thermal stability and shape stability of FSPCMs, which is helpful in understanding the shape stability mechanism and broadening the potential application of FSPCMs.
文摘运用文献计量学的方法,对1986—2016年科学引文索引扩展版(SCI-E)中收录的有关"臭氧和乙烯叉二脲(EDU)"的文章进行文献类型、研究学科方向、年度发文量、作者、国家或地区、研究机构、来源出版物名称、基金资助机构分析,并对研究重点、研究中采用的臭氧浓度、臭氧处理方式、EDU施用浓度、EDU施用部位、所选用的植物材料等进行了统计。结果表明,学科方向以生态环境科学为主;文献数量在年际间呈波动状态,2015年发表文献数量最多;Manning W J在此方向发表论文数量居于首位;美国、印度、意大利等国对该领域比较重视;《环境污染》期刊上发表的相关研究论文数量最多;目前,EDU对臭氧胁迫下农作物产量、植物可见伤害及植物光合作用变化情况较受关注。今后应加大EDU缓解臭氧伤害的分子机理及植物施用EDU后毒物学方面的研究。
文摘Soil microbial activity is recognized as an important factor affecting nitrogen (N) release from slow-release fertilizers. However,studies on the effect of size and activity of soil microflora on fertilizer degradation have provided contrasting results. To date, no clear relationships exist between soil microbial activity and the release of N from slow-release fertilizers. Hence, the aim of this study was to better understand such relationships by determining the release of N from three slow-release fertilizers in soils with different microbial activities. Soils were amended with urea-formaldehyde (UF), isobutylidene diurea (IBDU), and crotonylidene diurea (CDU). Urea, a soluble fertilizer, was used as the control. Fertilized soil samples were placed in a leaching system, and the release of N was determined by measuring ammonium-N and nitrate-N concentrations in leachates during 90 d of incubation. Non-linear regression was used to fit N leaching rate to a first-order model. In all the treated soils, N was released in the order: urea (89%–100%) > IBDU (59%–94%) >UF (46%–73%) > CDU (44%–56%). At the end of incubation, N released from CDU did not differ (P > 0.05) among soils. On the contrary, UF and IBDU released significantly lower (P < 0.05) amounts of N in the soil with higher microbial activity and lower pH.The rate constant (K_0) for UF was lower (P < 0.05) in the soil with lower pH. Taken together, our results indicated that soil microbial size and microbial activity had a marginal effect on fertilizer mineralization.
