The Effect of Composite Nucleating Agent on the Crystallization Behavior of Branched Poly (Lactic Acid)

Composite nucleating agent (CNA) consisting of zinc oxide as a crystallization promoter and phenylphosphonic acid zinc salt (PPZn) as an heterogeneous nucleation agent was employed to improve the crystallization behaviors of branched poly (lactic acid) (B-PLA) which was prepared by use of multi-functional epoxy-based chain extender (CE). The differential scanning calorimeter results showed that the crystallinity and crystallization temperature of prepared B-PLA/CNA were higher than that of linear poly (lactic acid) (L-PLA) and B-PLA at a high cooling rate. The corresponding phenomena of heterogeneous nucleation of B-PLA/CNA were observed by means of polarized optical microscope. The crystalline mechanism research results show that the degradation reaction and chain extending reaction were occurred simultaneously after the addition of CE and CNA into the PLA, PPZn as an effective nucleation points could increase the nucleation density and the degraded short molecular chains with higher chain mobility would improve crystal growth during the crystallization of the branched PLA. Non-isothermal cold crystallization kinetics of various B-PLA with different content of CNA was studied. The corresponding result showed that the crystallinity and crystallization rate increased obviously with the CNA content greater than or equal to 5phr, as well as the crystallization time decreased. The similar experimental results of non-isothermal and isothermal melt crystallization kinetics also showed that CNA had a significant impact on crystallization behavior of B-PLA.     

活性炭吸附-超临界CO2解吸附四氯乙烯的特性研究

应用Boyd理论研究了活性炭吸附水中四氯乙烯(PCE)的吸附速率以及超临界CO2萃取PCE饱和活性炭的解吸附速率.结果表明,在0.5～48.0 h内,吸附速率曲线具有直线相关关系,R2=0.996 0,其吸附速率可用粒内扩散系数Di表示,Di=4.00×1010cm2/s;在超临界CO2解吸附过程中,在1～5 min内,时间与解吸附率存在直线相关关系,R2=0.947 5,其解吸附速率用粒内扩散系数Di/SF表示,Di/SF=-5.19×10-5cm2/s,比Di大105倍,说明超临界流体具有优越的传输性能;用Boyd理论可粗略描述活性炭吸附-超临界CO2解吸附PCE的过程.     

小型养殖塘水体中CH4、CO2和N2O浓度的时空变化特征及影响因素

养殖塘作为重要的温室气体排放源,水体中温室气体浓度的变化不仅是准确量化温室气体排放量的基础,还是明确其影响因素的重要依据.基于顶空平衡-气相色谱仪法对长三角一处典型的小型养殖塘水体中CH₄、CO₂和N₂ O浓度的时空变化特征以及影响因素进行了分析.结果表明,除春季外,在水温影响下,CH₄和N₂ O浓度在午间或午后出现高值;受水温和水生植物光合作用影响,CO₂浓度的高值出现在晨间光合作用较弱的时候.养殖塘水体中CH₄和CO₂浓度呈现秋季最高、冬季最低的季节变化特征,c（CH₄）在秋季和冬季的均值分别为176.34 nmol·L^-1和32.75 nmol·L^-1,主要受气温、水温和溶解氧（DO）影响;c（CO₂）秋季和冬季的均值分别为134.37 μmol·L^-1和23.10 μmol·L^-1,主要受水生植物光合作用和pH影响;c（N₂ O）在夏季最高,冬季最低,均值分别为97.05 nmol·L^-1和19.41 nmol·L^-1,主要受气温和水温影响.在空间上,垂直方向上,夏季养殖塘c（CH₄）随水深的加深而降低,表层与底层、中间层的浓度差值为71.28 nmol·L^-1和42.80 nmol·L^-1,秋季随水深的加深而升高,底层与表层的浓度差值为163.94 nmol·L^-1.c（CO₂）在夏季和秋季都表现为随着水深的加深而升高,其底层与表层的浓度差值分别为18.69 μmol·L^-1和29.90 μmol·L^-1.N₂ O浓度在垂直方向上无明显变化规律.水平方向上,夏季饲料及春季鸡粪投放的区域会出现CH₄、CO₂和N₂ O浓度的高值,春季和夏季CH₄浓度约为其他区域的1.34~1.98倍和1.95~2.42倍,春季N₂ O浓度和夏季CO₂浓度约为其他区域的1.13~1.26倍和1.39~1.74倍.     

A numerical simulation model of cyclic hardening behavior of AC4C-T6 for LNG cargo pump using finite element analysis

This paper is concerned with the evaluation of cyclic hardening models within the stress–strain behavior of aluminum alloy AC4C-T6 that can be used to LNG cargo pump operating in cryogenic temperature. To insure the strength assessment of LNG cargo pump, material model of cyclic hardening and plasticity for aluminum alloy AC4C-T6 is investigated through FEA (Finite Element Analysis) with various hardening options including linear and non-linear hardening, isotropic and kinematic hardening, and combined hardening model. Monotonic tensile and cyclic tensile experiments for AC4C-T6 alloy were performed at room temperature and temperature of ?165 °C. Parameters of each hardening model are obtained from the experimental data; thus five hardening models are numerically simulated thereafter. Appropriate hardening models which describe the cyclic stress–strain relationship are investigated through the simulations of cyclic hardening behavior by FEA. In order to verify the predicted behavior of cyclic hardening obtained by FEA, the results of FEA and those measured by experiments are compared.     

Regional efforts to mitigate climate change in China: a multi-criteria assessment approach

The task of mitigating climate change is usually allocated through administrative regions in China. In order to put pressure on regions that perform poorly in mitigating climate changes and highlight regions with best-practice climate policies, this study explored a method to assess regional efforts on climate change mitigation at the sub-national level. A climate change mitigation index (CCMI) was developed with 15 objective indicators, which were divided into four categories, namely, emissions, efficiency, non-fossil energy, and climate policy. The indicators’ current level and recent development were measured for the first three categories. The index was applied to assess China’s provincial performance in climate protection based on the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method. Empirical results show that the middle Yangtze River area and southern coastal area perform better than other areas in mitigating climate change. The average performance of the northwest area in China is the worst. In addition, climate change mitigation performance has a negative linear correlation with energy self-sufficiency ratio but does not have a significant linear correlation with social development level. Therefore, regional resource endowments had better be paid much more attention in terms of mitigating climate change because regions with good resource endowments in China tend to perform poorly.     

Betaine removal during thermo- and mesophilic aerobic batch biodegradation of beet molasses vinasse: influence of temperature and pH on the progress and efficiency of the process

The key issue in achieving a high extent of biodegradation of beet molasses vinasse is to establish the conditions for the assimilation of betaine, which is the main pollutant in this high-strength industrial effluent. In the present study, aerobic batch biodegradation was conducted over the temperature range of 27-63°C (step 9°C), at a pH of 6.5 and 8.0, using a mixed culture of bacteria of the genus Bacillus. Betaine was assimilated at 27-54°C and the pH of 8.0, as well as at 27-45°C and the pH of 6.5. The processes where betaine was assimilated produced a high BOD(5) removal, which exceeded 99.40% over the temperature range of 27-45°C at the pH of 8.0, as well as at 27°C and the pH of 6.5. Maximal COD removal (88.73%) was attained at 36°C and the pH of 6.5. The results indicate that the process can be applied on an industrial scale as the first step in the treatment of beet molasses vinasse.     

Effects of varying dilutions, pH, temperature and cations on spermatozoa motility in fish Larimichthys polyactis

The objectives of this present study were to assess the effects of varying dilutions, pH, temperature and cations on spermatozoa motile parameters (SMPs) in fish Larimichthys polyactis. Optimal SMPs were observed when emen was diluted in artificial seawater (ASW) at a ratio of 1 to 100, with temperature of 10 degreesC and pH 8.0. The spermatozoa of L. polyactis were immotile in distilled water and motile in solution containing different cations. Maximum SMPs were obtained in each solution containing 0.4 mol NaCI, 0.4 mol KCI, 0.2 mol CaCI2 and 0.2 mol MgCl2. This study provides baseline knowledge of L. polyactis spermatozoa sensitivity of pH, temperature and cationic effects.     

镧、铈、钕对小鼠肝细胞核的氧化损伤作用

轻稀土元素进入生物体后主要累积于肝脏,进入肝细胞,分布于细胞核上.为探讨轻稀土元素对小鼠肝细胞核的氧化损伤作用,选用5周龄雄性封闭群(ICR)小鼠灌喂10、20和40 mg·kg-1的稀土元素镧(La)、铈(Ce)和钕(Nd),6周后测定小鼠肝细胞核中超氧化物岐化酶(SOD)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(...