桉树遗态Fe/C复合材料对水中Cr(Ⅵ)的动态吸附探讨

为研究桉树遗态Fe/C复合材料(PBGC-Fe/C)对水中Cr(Ⅵ)的净化能力及其动态吸附过程,以PBGC-Fe/C吸附剂为固定床,选择溶液初始p H、进水流速、溶液初始浓度、吸附剂投加量和环境温度为影响因素开展动态吸附试验分析.结果表明:在溶液初始p H为2,进水流速为5.14 m L/min,吸附剂投加量为2 g和环境温度为35℃的条件下,PBGC-Fe/C对水中Cr(Ⅵ)的最佳平衡吸附容量达到10.72 mg/g;提高溶液初始p H、进水流速和溶液初始质量浓度或降低吸附剂投加量均可缩短反应穿透时间和衰竭时间;Thomas和Yoon-Nelson模型均能较好地描述PBGC-Fe/C对水中Cr(Ⅵ)的动态吸附过程,说明该吸附过程中内部扩散和外部扩散均为非限速步骤,吸附速率常数(kTh)随着进水流速的增大从1.3×10-3m L/(min·mg)升至2.6×10-3m L/(min·mg),随着溶液初始质量浓度的增大从2.7×10-3m L/(min·mg)降至1.4×10-3m L/(min·mg).研究显示,PBGC-Fe/C对水中Cr(Ⅵ)具有较好的动态吸附能力,具有较好的市场应用前景.

多孔硅——一种新形态的硅材料

多孔硅（ｐｏｒｏｕｓ Ｓｉｌｉｃｏｎ）是指通过对氢氟酸溶液中的晶体硅片进行阳极氧化，在硅衬底上形成的多孔态的硅材料．本文介绍了多孔硅的形成规律和结构形貌，并对其光学性质和形成机制仆行了简要的评介，最后以多孔硅在大规模集成电路中的应用为主讨论了它的技术应用．

NiTi形状记忆合金表面改性的研究进展

近等原子比的NiTi合金以其优异的特性在临床医学得到广泛应用,但是由于Ni离子溶出引致的潜在生物毒性以及无生物活性,抑制了NiTi合金在生物医用领域的进一步发展。为了改善上述缺陷,对NiTi合金进行表面处理成为当前国内外NiTi合金研究的热点。从不同的改性工艺出发,全面阐述了近年来国内外对致密态和多孔态NiTi合金进行表面改性的研究进展,对各种方法可能出现的问题进行了分析,指出现有的各种表面改性方法不能有效实现对多孔NiTi合金内部孔隙进行改性,并针对这一症结提出了采用原位氮化法对多孔NiTi合金进行改性的可行性。

Analysis of genetic diversity for wild and captive green peafowl populations by random amplified polymorphic DNA technique

The genetic diversity of the populations for 14 wild green peafowls (Pavo muticus) and 18 captive green pea-fowls was investigated by using the technology of random amplified polymorphic DNA (RAPD). Totally 161 and 166 ampli-fied bands were obtained by using 23 arbitrary primers to amplify the genomic DNA of wild and captive green peafowls re-spectively. The results showed that the average relative genetic distance of the wild and captive green peafowls popula-tions was 0.0555 and 0.1355, respectively, and difference of the average relative genetic distances between the two popu-lations was 0.1635. The Shannon diversity index for the wild and captive green peafowl populations was 0.4348 and 1.0163, respectively, which means that there exists significant difference in genetic diversity between the two populations, and the genetic diversity of wild green peafowl was low. The two populations originated from two different families according to analysis by the UPGMA method. This research can provide the theoretical basis for supervising genealogies management of peafowl populations.

Theoretical Study of Interaction Between S2 and SiHx （x=1, 2, 3） in Porous Silicon

The interaction between S2 molecule and SiHx （x=1, 2, 3） in porous silicon is investigated using the B3LYP method of density functional theory with the lanl2dz basis set. The model of porous silicon doped with CH3, Si-O-Si and OH species is built. By analyzing the binding energy and electronic transfer, we conclude that the interaction of S2 molecule with SiHx （x=1, 2, 3） is much stronger than the interaction of S2 molecule with CH3 and OH, as S2 molecule is located in different sites of the model. Using the transition state theory, we study the Si2H6＋S2→H3SiH2SiS＋HS reaction, and the reaction energy barrier is 50.2 kJ/mol, which indicates that the reaction is easy to occur.

Development of 101 Novel EST-Derived Single Nucleotide Polymorphism Markers for Zhikong Scallop (Chlamys farreri)

Zhikong scallop(Chlamys farreri) is an important maricultured species in China.Many researches on this species,such as population genetics and QTL fine-mapping,need a large number of molecular markers.In this study,based on the expressed sequence tags(EST),a total of 300 putative single nucleotide polymorphisms(SNPs) were selected and validated using high resolution melting(HRM) technology with unlabeled probe.Of them,101(33.7%) were found to be polymorphic in 48 individuals from 4 populations.Further evaluation with 48 individuals from Qingdao population showed that all the polymorphic loci had two alleles with the minor allele frequency ranged from 0.046 to 0.500.The observed and expected heterozygosities ranged from 0.000 to 0.925 and from 0.089 to 0.505,respectively.Fifteen loci deviated significantly from Hardy-Weinberg equilibrium and significant linkage disequilibrate was detected in one pair of markers.BLASTx gave significant hits for 72 of the 101 polymorphic SNP-containing ESTs.Thirty four polymorphic SNP loci were predicted to be non-synonymous substitutions as they caused either the change of codons(33 SNPs) or pretermination of translation(1 SNP).The markers developed can be used for the population studies and genetic improvement on Zhikong scallop.

Effect of heat treatment of Mn-Cu precursors on morphology of dealloyed nanoporous copper

Nanoporous copper with nano-scale pore size was synthesized by dealloying Mn-Cu precursor alloy using a free corrosion method. The effects of heat treatment of Mn-Cu precursors on alloy phase, morphology and composition of the resultant nanoporous copper were investigated. It is revealed that the compositions distribute homogeneously in the bulk Mn-Cu precursors, which consequently results in a more fully dealloying for forming nanoporous copper. The alloy phase changes from Cuo.a9Mno.51 and Cuo.21Mno.79 of non-thermally treated precursor to Cuo.33Mn0.67 of heat treated alloy. The residual Mn content in nanoporous copper is decreased from 12.97% to 2.04% （molar fraction） made from the precursor without and with 95 h heat treatment. The typical pore shape of nanoporous copper prepared by dealloying the precursor without the heat treatment is divided into two different zones： the uniform bi-continuous structure zone and the blurry or no pore structure zone. Nanoporous copper is of a uniform sponge-like morphology made from the heat-treated precursor, and the average ligament diameter is 40 nm, far smaller than that from the non-thermally treated precursor, in which the average ligament diameter is estimated to be about 70 nm.

Influence of dynamic recrystallization on microstructure and mechanical properties of welding zone in Al-Mg-Si aluminum profile during porthole die extrusion

The effect of dynamic recrystallization(DRX)on the microstructure and mechanical properties of 6063 aluminum alloy profile during porthole die extrusion was studied through experiment and simulation.The grain morphology was observed by means of electron backscatter diffraction(EBSD)technology.The results show that,at low ram speeds,increasing the ram speed caused an increase in DRX fraction due to the increase of temperature and strain rate.In contrast,at high ram speeds,further increasing ram speed had much less effect on the temperature,and the DRX faction decreased due to high stain rates.The microhardness and fraction of low angle boundaries in the welding zones were lower than those in the matrix zones.The grain size in the welding zone was smaller than that in the matrix zone due to lower DRX fraction.The decrease of grain size and increase of extrudate temperature were beneficial to the improvement of microhardness.

Fluids in Mesopores： A New Theory and Applications

While hysteresis in the adsorption of fluids in porous material is known since about one century, the thermodynamic treatment of this phenomenon is still not settled. We propose to accept that thermodynamics is not designed to deal with confined systems and we propose to introduce a new set of rules for describing the behavior of confined systems. This proposal is based on a large number of simulation calculations. The employed method of simulation has been shown to describe static and dynamic phenomena encountered in this field. The newly formulated theory incorporates the phenomenon of hysteresis without inconsistencies. Further, it will be shown that the theory allows simulating diffusional and convectional transport （nanofluidics） by a unified approach without the need to introduce capillary forces （surface or interface tensions） by phenomenological parameters. The second part of the paper is devoted to the potential for practical use. It turns out that the new concepts open the route to employing unusual states of matter found in porous systems which may lead to improved applications. In particular we will focus on the possibility to drive a fluid in a pore into states with negative pressure under static and under dynamic conditions. It turns out that states with negative pressure can be reproducibly controlled. Negative pressure states are in principal known since the time of Torricelli and they have been discussed in the literature as experimentally accessible situations. Still, they have not been turned into practical usefulness which is likely to be caused by the notion of their metastability in macroscopic systems. Possible applications refer to controlling chemical reactions as well as new routes to efficient separation processes that are difficult to handle by conventional techniques.

Influence of polarized bias and porous silicon morphology on the electrical behavior of Au-porous silicon contacts

This paper reports the surface morphology and I-V curves of porous silicon （PS） samples and related devices. The observed fabrics on the PS surface were found to affect the electrical property of PS devices. When the devices were operated under different external bias （10 V or 3 V） for 10 min, their observed obvious differences in electrical properties may be due to the different control mechanisms in the A1/PS interface and PS matrix morphology.

Nonlinear Diffusion and Transient Osmosis

We investigate both analytically and numerically the concentration dynamics of a solution in two containers connected by a narrow and short channel, in which diffusion obeys a porous medium equation. We also consider the variation of the pressure in the containers due to the flow of matter in the channel. In particular, we identify a phenomenon, which depends on the transport of matter across nano-porous membranes, which we call ＂transient osmosis＂. We find that nonlinear diffusion of the porous medium equation type allows numerous different osmotic-like phenomena, which are not present in the case of ordinary Fickian diffusion. Experimental results suggest one possible candidate for transiently osmotic processes.

Quantitative Simulation on Soil Moisture Contents of Two Typical Vegetation Communities in Sanjiang Plain,China

Different types of vegetation occupy different geomorphology and water gradient environments in the San- jiang Plain, indicating that the soil moisture dynamics and water balance patterns of the different vegetation communi- ties might differ from each other. In this paper, a lowland system, perpendicular to the Nongjiang River in the Honghe National Nature Reserve （HNNR）, was selected as the study area. The area was occupied by the non-wetland plant forest and the typical wetland plant meadow. The Microsoft Windows-based finite element analysis software package for simulating water, heat, and solute transport in variably saturated porous media （HYDRUS）, which can quantita- tively simulate water, heat, and/or solute movement in variably-saturated porous media, was used to simulate soil moisture dynamics in the root zone （20-40 cm） of those two plant communities during the growing season in 2005. The simulation results for soil moisture were in a good agreement with measured data, with the coefficient of determi- nation （R2） of 0.44-0.69 and root mean square error （RMSE） ranging between 0.0291 cm3/cm3 and 0.0457 cm3/cm3, and index of agreement （d） being from I）.612 to 0.968. During the study period, the volumetric soil moisture content of meadow increased with the depth and its coefficient of variation decreased with the depth （from 20 cm to 40 cm）, while under the forest the soil moisture content at different depths varied irregularly. The calculated result of water budget showed that the water budget deficit of the meadow was higher than that of the forest, suggesting that the meadow is more likely to suffer from water stress than the forest. The quantitative simulation by HYDRUS in this study did not take surface runoff and plant growth processes into account. Improved root water uptake and surface runoff models will be needed for higher accuracy in further researches.

Self-diffractionin Porous Silicon/PMMA-DR1 Composite Fil ms

Two-layer structure consisting of PS/PMMA-DR1 composite film planar waveguide layer on porous silicon cladding layer was fabricated in our experiment. The induced grating based on the third nonlinear optical properties was formed by interaction of two Nd∶YAG laser beams at 1064nm in the porous silicon/PMMA-DR1 waveguide. The diffraction efficiency of the first order diffracted light is measured to be about 0.2% of the total output.

Adsorption of Metal Ions by Sorbents Composed of Marine Alga Saccharina bongardiana and Poriferous Aluminosilicates

The development of gold and cobalt-copper-nickel deposits in Kamchatka threatens the loss of biodiversity in spawning rivers and lakes and has negative effects on coastal ecosystems. To reduce pollution by mining wastes, filters with dried marine alga Saccharina bongardiana in combination with zeolite and pumice are recommended. Combined Saccharina-based sorbents remove heavy metal ions more effectively, increasing adsorption capacity by five times compared to mineral （pumice） sorhents. As a result of desorption, a tenfold increase of the solution concentration is reached after the first sorption cycle. Valuable elements （Ni, Co, Cu etc.） can then be extracted from concentrates by any known method. It increases economic efficiency of the mining industry due to recycling of non-ferrous metals. Saccharina-based sorbents can be also utilized for purification of polluted natural waters. It may serve as environmental protection measure and provide for ecological safety of the unique natural environment of Kamchatka and its bioresources.

Dynamic indentation response of porous SiC/Ti-based metallic glass composite

Porous SiC/Ti-based metallic glass composite (Ti-BMGC), a new kind of composite, has significant application prospectin the field of light armor. To evaluate the dynamic mechanical response of the composite, dynamic Vickers hardness andindentation-induced deformation behavior were investigated by comparison with that under static indentation. The dynamic hardnesswas measured by a modified split Hopkinson pressure bar (SHPB). The dynamic hardness is obviously greater than the statichardness. The brittleness parameter under dynamic indentation is also greater than that under static indentation. Although thedynamic indentation induced more severe deformation behavior than the static indentation, the deformation and fracturecharacteristics in the two loading cases are nearly the same, both exhibiting extensive cracks in the SiC phase and severe plasticdeformation in the metallic glass phase.

Theoretical analysis of influencing factors on resistance in the process of gas migration in coal seams

Inspired by previous resistance models for porous media, a resistance expression of gas migration within coal seams based on the ideal matchstick geometry, combined with the Darcy equation and the modified Poiseuille equation is proposed. The resistance to gas migration is generally dynamic because of the variations in adsorption swelling and matrix shrinkage. Due to the limitations of experimental conditions,only a theoretical expression of resistance to gas migration in coal is deduced, and the impacts of tortuosity, effective stress and pore pressure on the resistance are then considered. To validate the proposed expression, previous data from other researchers are adopted for the history matching exercise, and the agreement between the two is good.

Preliminary genetic linkage map of the abalone Haliotis diversicolor Reeve

Haliotis diversicolor Reeve is one of the most important mollusks cultured in South China. Preliminary genetic linkage maps were constructed with amplified fragment length polymorphism (AFLP) markers. A total of 2 596 AFLP markers were obtained from 28 primer combinations in two parents and 78 offsprings. Among them, 412 markers (15.9%) were polymorphic and segregated in the mapping family. Chi-square tests showed that 151 (84.4%) markers segregated according to the expected 1:1 Mendelian ratio (P<0.05) in the female parent, and 200 (85.8%) in the male parent. For the female map, 179 markers were used for linkage analysis and 90 markers were assigned to 17 linkage groups with an average interval length of 25.7 cm. For the male map, 233 markers were used and 94 were mapped into 18 linkage groups, with an average interval of 25.0 cm. The estimated genome length was 2 773.0 cm for the female and 2 817.1 cm for the male map. The observed length of the linkage map was 1 875.2 cm and 1 896.5 cm for the female and male maps, respectively. When doublets were considered, the map length increased to 2 152.8 cm for the female and 2 032.7 cm for the male map, corresponding to genome coverage of 77.6% and 72.2%, respectively.

Combined Effect of Magnetic Field and Thermal Dispersion on a Non-Darcy Mixed Convection

This paper is devoted to investigate the influences of thermal dispersion and magnetic field on a hot semi-infinite vertical porous plate embedded in a saturated Darcy-Forchheimer-Brinkman porous medium. The coefficient of thermal diffusivity has been assumed to be the sum of the molecular diffusivity and the dynamic diffusivity due to mechanical dispersion. The effects of transverse magnetic field parameter (Hartmann number Ha), Reynolds number Re (different velocities), Prandtl number Pr (different types of fluids) and dispersion parameter on the wall shear stress and the heat transfer rate are discussed.

Double-peaked decay of transient photovoltage in nanoporous ZnO/n-Si photodetector

In the present work,a nanoporous ZnO/n-Si structure has been proposed as a new type infrared photodetector.Triggered by one laser pulse with wavelength of 1064 nm,this structure exhibits a double-peak decay of transient photovoltage.Also,the time interval between these two peaks increases linearly with the increase of irradiated pulsed energy,indicating the promising application of this hetero-junction in photo-energy detection of infrared pulsed laser.A possible mechanism for this particular photoresponse has been discussed.

Robust metal–organic framework with multiple traps for trace Xe/Kr separation

Direct separation of Xe and Kr from air or used nuclear fuel(UNF)off-gas by means of porous adsorbents is of industrial importance but is a very challenging task.In this work,we show a robust metal-organic framework(MOF),namely ECUT-60,which renders not only high chemical stability,but also unique structure with multiple traps.This leads to the ultrahigh Xe adsorption capacity,exceeding most reported porous materials.Impressively,this MOF also enables high selectivity of Xe over Kr,CO2,O2,and N2,leading to the high-performance separation for trace quantitites of Xe/Kr from a simulated UNF reprocessing off-gas.The separation capability has been demonstrated by using dynamic breakthrough experiments,giving the record Xe uptake up to 70.4 mmol/kg and the production of 19.7 mmol/kg pure Xe.Consequently,ECUT-60 has promising potential in direct production of Xe from UNF off-gas or air.The separation mechanism,as unveiled by theoretical calculation,is attributed to the multiple traps in ECUT-60 that affords rigid restrict for Xe atom via van der Waals force.