K_2ZrF_6加入量对Al-Zr中间合金凝固组织的影响

针对Al-K_2ZrF_6体系,采用熔盐反应法制备了Al-Zr中间合金。研究了K_2ZrF_6加入量(分别占体系质量分数的12%、14%、16%和18%)对中间合金凝固组织的影响。结果表明:熔盐反应生成的Al_3Zr相呈现为颗粒状,平均尺寸3～10μm。随着K_2ZrF_6含量的增加,Al_3Zr颗粒的尺寸更细小,体积分数逐渐增大,分布更均匀。

Oligomerization of 1-Decene: Catalyzation by Immobilized AlCl_3/γ-Al_2O_3 Catalyst in Fixed-bed Reactor

1-Decene was oligomerized over the supported AlCl3/γ-Al2O3 catalyst in a fixed-bed reactor. The effects of temperature and LHSV on oligomerization of 1-decene were investigated and the synthetic PAO was characterized with GC technique. Furthermore, the life of immobilized catalyst was tested and the mechanism of catalyst deactivation was discussed. The results showed that with an increasing temperature, the PAO yield increased and the kinematic viscosity of oil decreased. The GC results indicated that the synthesized PAO was a mixture consisting of dimers, trimers, tetramers and pentamers. The results of chloride content measurements and BET tests showed that catalyst deactivation could be mainly attributed to the loss of active components.

Wettability and interfacial reactions of PdNi-based brazing fillers on C-C composite

The wettability and interfacial reactions of four kinds of PdNi-based brazing fillers on C-C composite were studied with the sessile drop method.The results showed that the wettability of these brazing fillers was improved with the increase of Cr content. Cr distributed at the interface of brazing filler/C-C composite and the formation of Cr23C6 phase was speculated.In the interface between Ni-33Cr-24Pd-4Si brazing filler and C-C composite,element Cr reacted with C-C to form Cr-C reaction layer.Pd together with Si participated in the interfacial reactions and formed Pd2Si and Pd3Si phases.Furthermore,in this reaction zone,the residual brazing alloy became Ni-rich and Pd-depleted.

Effects of Forest Gaps on Some Microclimate Variables in Castanopsis kawakamii Natural Forest

The objective of this study was to understand the effects of forest gap and variations in different seasons, gap size, locations and diurnal variations on forest microclimate and soil water content. Spatial and temporal distribution features oi air temperature （TA）, soil temperature （Ts）, relative humidity （h） and soil water content （ψ） were measured in Castanopsis kawakamii natural forest gaps created by a severe typhoon or fallen dead trees. The results showed that： （1） the variations of TA, h, and Tsin four seasons were extremely significant. The variations of ψ in four seasons were extremely significant except for those between spring and summer. （a） The diurnal variations of TA and Tswere expressed with a single peak curve. The diurnal variations of h and ψ presented a high-low-high trend （3） The variations of TA, h, and Ts were extremely significant among the large, medium and small gaps in C. kawakamii natural forest. Medium gaps had the highest TA and the lowest h while small gaps were jusl contrary to medium gaps. The variations of T were extremely significant for large, medium and small gaps except those between the medium and large gaps （4） The TA, h, Ts and ψ were decreased from the gap center, canopy gap, expanded gap to understory. These results will help further our understanding of the abiotic and consequent biotic responses to gaps in the mid-subtropical broadleaved forests, which also provide a theoretical basis for the scientific management and population restoration of C. kawakamii natural forest.

Reduction of lead sulfate to lead sulfide with carbon monoxide

In order to decrease the solubility of PbSO4 and enhance lead recovery from PbSO4 bearing wastes, CO was employed as a reductant to transform PbSO4 into Pb S. Reaction system was established and reductive thermodynamics of PbSO4 was calculated by software HSC 5.0. The effects of gas concentration, reaction temperature, time and mass of sample on reduction of PbSO4 were examined by thermogravimetry(TG) and XRD. Roasting tests further verify the conclusions of thermodynamic and TG analyses. The results show that increasing temperature in the reasonable range and CO content are favorable for the formation of Pb S. The reduction process is controlled by chemical reaction and calculation value of the activation energy is 47.88 k J/mol.

Characteristics of extracellular fluorescent substances of aerobic granular sludge in pilot-scale sequencing batch reactor

The aerobic granular sludge was cultivated in a pilot-scale sequencing batch reactor （SBR）, and some of the granules were stored at 8 ℃ for 150 d. Extracellular polymeric substances （EPS） of sludge samples were extracted and analyzed during the granulation and storage process. The results show that the contents of protein and EPS increase along with the granulation process, while polysaccharides remain almost unchanged. The content of protein in EPS is almost two-fold larger than that of polysaccharides in granular sludge cultivated with municipal wastewater. Moreover, some of the granules disintegrate during storage, corresponding to the decrease of protein contents in EPS. Three peaks are identified in three-dimensional excitation emission matrix （EEM） fluorescence spectra of the EPS in the aerobic granules. Two peaks （A and B） are attributed to the protein-like fluorophores, and the third （peak C） is related to visible fulvic-like substances. Peak A gradually disappears during storage, while a new peak related to ultraviolet fulvic acid （peak D） is formed. The formation and the stability of aerobic granules are closely dependent on the quantity and composition of EPS proteins. Peak C has no obvious changes during granulation, while the fulvic-like substances present an increase in fluorescence intensities during storage, accompanied with an increase in structural complexity. The fulvie-like substances are also associated with the disintegration of the aerobic granules.

Biochemical response of the mussel Mytilus coruscus(Mytiloida:Mytilidae) exposed to in vivo sub-lethal copper concentrations

Many aquatic organisms are negatively affected by exposure to high copper concentrations. We investigated the biochemical response of the mussel Mytilus coruscus （Mytiloida： Mytilidae） to copper exposure. In vivo bioassays using M. coruscus and different copper concentrations were conducted. The activity of six biomarkers, namely superoxide dismutase （SOD）, catalase （CAT）, acid phosphatase （ACP）, alkaline phosphatase （AKP）, glutamic-oxaloacetic transaminase （GOT） and glutamic-pyruvic transaminase （GPT） were measured. Survival rates decreased with increased copper concentrations and exposure times. The LCs0 values at 48, 72, and 96 h exposure were 0.48, 0.37, and 0.32 rag/L, respectively. Within digestive glands, CAT activity increased with increasing Cu concentrations. The activity of AKP showed no significant change, while the remaining four enzymes showed decreasing activity with increasing Cu concentrations. Within the gills, AKP activity increased when the Cu concentration was 0.05 mg/L, but showed no significant changes at higher concentrations. Activity of CAT and ACP within gills tended to decrease with increasing Cu concentration. The activity of SOD and GPT decreased at an exposure concentration of 0.2 mg/L. GOT activity within gills decreased at 0.1 mg/L and increased at an exposure concentration of 0.2 mg/L. Within the adductor muscle, AKP activity increased at 0.05 mg/L but did not change at higher exposure concentrations. ACP activity within adductor muscle tissue showed no change, while activities of CAT, GOT and GPT decreased with increasing Cu concentrations. SOD activity within the adductor muscle tissue significantly decreased at the 0.02, 0.05 and 0.2 mg/L exposure concentrations. Our results show tissue specific differences for the six biomarkers in for M. coruscus. Our findings provide the basis for the establishment of reference activity levels against which biomarker changes can be estimated, and are essential preliminary steps in development of in vivo bioassays.

The Generation of a Reduced Mechanism for Flame Inhibition by Phosphorus Containing Compounds Based on Path Flux Analysis Method

In order to analyze the complex chemical kinetic mechanism systematically and find out the redundant species and reactions, a numerical platform for mechanism analysis and simplification is established basing on Path Flux Analysis （PFA）. It is used to reduce a detailed mechanism for flame inhibited by phosphorus containing compounds, a reduced mechanism with 65 species and 335 reactions is obtained. The detailed and reduced mechanism are both used to calculate the freely-propagating premix C3H8/air flame with different dimethyl methylphosphonate doped over a wide range of equivalence ratios. The concentration distributions of free radicals and major species are compared, and the results under two different mechanisms agree well. The laminar flame speed obtained by the two mechanisms also matches well, with the maximum relative error introduces as a small value of 1.7%. On the basis of the reduced mechanism validation, the correlativity analysis is conducted between flame speed and flee radical concentrations, which can provide information for target species selection in the further mechanism reduction. By analyzing the species and reactions fluxes, the species and reaction paths which contribute the flame inhibition significantly are determined.