The hydration of blended cement at low<Emphasis Type="Italic">W/B</Emphasis> ratio

The hydration process, hydration product and hydration heat of blended cement paste mixed with mineral admixture and expansive agent at low W/B ratio are studied by XRD, thermo analysis, and calorimetry instrument, and they were compared with those of pure cement paste. The results show that pure cement and blended cement at low W/B ratio have the same types of hydration products, but their respective amounts of hydration products of various blended cements at same ages and the variation law of the amount of same hydration products with ages are different; The joint effect of tumefaction of gel-ettringite due to water absorption and the expansive pressure on the pore and rift caused by the crystalloid ettringite is the impetus of the volume expansion of cement paste, and the former effect is much greater than the latter one. HU Shu-guang: Born in 1957 Funded by 973 High-tech Project of China (No. 2001CB610704-2) and the Natural Science Foundation of Hubei Province(No. 2002AB075)     

The Hydration Characteristics and Expansion Machanism of Expansive Cement at Low W/B Ratio

1　IntroductionAnexpansiveagentcannotonlymakethestructurehasself waterproofperformance ,butalsoreducetheshrinkageandthecrackingofconcreteeffectively .Soitisextensivelyusedincommonconcrete .However,theappli cationofexpansiveagentinhigh strengthconcreteisnotattractedmuchattention .Itisnotonlybecauseofthebondageoftraditionalviewpointthatitsshrinkagevalueofhigh strengthconcreteismuchgreaterthanthatofcom monconcrete ,butalsothedeficiencyofadequatestudyonthehydrationcharacteristicsandexpansivemechan…     

The transformation of calcium phosphate bioceramics<Emphasis Type="Italic">in vivo</Emphasis>

To study the transformation process of calcium phosphate bioceramic in vivo, biodegradable porous β-tricalcium phosphate ceramics (β-TCP) were used in this experiment. The materials (ø5×8mm) were implanted in the tibia of rabbits. The β-TCP ceramics with bone tissue were retrieved, and treated for histology, and then observed by using a scanning electron microscope (SEM) and an electron probe X-ray microanalyzer (EMPA) every month. The results show that β-TCP ceramics bond to bone directly, new bones are forming and maturing with materials continuous degrading, and the materials are nearly replaced by the formed bone finally. Parts of the materials were degraded, absorpted and recrystallized, the others dispersped on the cancellous bone and the Haversian lamella with an irregular arrangement incorporating in bone formation directly by remodeling structure.     

Biocompatibility of Tri-block Bone-matrix Material in vitro

To evaluate the biocompatibility of poly（lactic acid/glycolic acid/ asparagic acid-copolyethylene glycol）（PLGA-[ASP-PEG]） tri-block copolymer in vitro, L929 fibroblast was co-cultured with the copolymer for cytotoxicity, hemolysis and pyrogen tests. And, compared with PLGA, the adhesiveness rate of the copolymer was calculated. The experimental results show that the toxicity gradation of the material was 0-1; L929 fibroblasts had a good cell morphology and proliferated rapidly on the surface of the material; hemolysis ratio was 3.08%; there was no pyrogen reaction. The adhesiveness of PLGA-[ASP-PEG] was better than that of the PLGA＇s（P〈0.05）. The results confirm that the PLGA-[ASP-PEG] has a good biocompatibility.     

The Hydration of Blended Cement at Low W/B Ratio

1　IntroductionThehydrationandhardeningprocessesofordinarycementhavebeenstudiedintensively[1-3 ] .Partlyreplac ingcementwithflyash ,slag ,orotheractivemineralad mixturecannotonlymodifythecementstrengthgrade ,re ducethehydrationheatofcement ,butalsomelioratethestructureofhardencementpaste[4] .Applyingexpansiveagentinordinaryconcretecancombinethebearingandwaterprooffunctionsofabuilding ,anditcanalsoreducetheshrinkageandpreventthecrackingofconcrete[5,6] .However ,thehydrationprocessofcementmixedw…     

A new processing method for the <Emphasis Type="Italic">AE</Emphasis> index

In this paper, we introduce an effective processing method to acquire the time derivative of the AE index as a coefficient. Using this coefficient, the AE index can be divided into the four stages: quiet, ascending, descending and active stages. The statistical results show that the ascending and descending stages of the AE index are dominant and occupy two thirds of the whole period. An analysis of the relationship between the occurrence frequencies of the Dst index and AE index in solar cycle 23 shows that the monthly variation of the occurrence frequencies of the ascending stage of AE is closely related to the decrease of the Dst index. Supported by the National Natural Science Foundation of China (Grant Nos. 40704031, 40536030)     

Synthesis and Characterization of LiCoxMn2-xO4 Cathode Materials

LiCoxMn2.04 cathode materials for lithium ion batteries were synthesized by mechanical activation-solid state reaction at 750 ℃ for 24 h in air atmosphere, and their crystal structure, morphology, element composition and electrochemical performance were characterized with XRD, SEM, ICP-AES and charge-discharge test. The experimental results show that all samples have a single spinel structure, well formed crystal shape and uniformly particle size distribution. The lattice parameters of LiCo Mn2-xO4 decrease and the average oxidation states of manganese ions increase with an increase in Co content. Compared with pure LiMn2O4, the LiCo Mn2xO4 （x=0.03-0.12） samples show a lower special capacity, but their cycling life are improved. The capacity loss of LiCo009Mn191O4 and LiCo0.1Mn1.88O4 is only 1.85% and 0.95%, respectively, after the 20th cycle. The improvement of the cycle performance is attributed to the substitution of Co at the Mn sites in the spinel structure, which suppresses the Jahn-Teller distortion and improves the structural stability.     

Structure and electrochemical properties of LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript>−<Emphasis Type="Italic">x</Emphasis>F<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>

LiMn₂O₄−_xF_x prepared by the sol-gel method has a perfect crystal formation. The crystal particle size of the material was medium and distributed uniformly. The substitution of F for O increased the specific capacity of the material at the cost of the cycleability. The explanation of this results is that the F decreases the valence of Mn, that is, more Mn³⁺ and less Mn⁴⁺ exist in the material. The increase of Mn³⁺ will improve the initial specific capacity and Mn³⁺ is the original reason for Jahn-Teller effect that caused the poor cycleability of the cathode material by the micro-distortion of the crystal structure. In addition, the expanded measurement of the crystal lattice is also the reason for the poor cycleability. Therefore, the results of F-substitution and cation-substitution are opposite. If the two methods are combined, they can compensate the inability each other and the satisfactory results may be obtained. XIA Jun-lei: Born in 1977 Funded by the National Natural Science Foundation of China (No. 59972026)     

Investigation of HAP Nanopartieles Absorbed by Hepatoma Cells in vitro

Many particles are found in the cytoplasm area after the mixture of hydroxyapatite （HAP） nanoparticles and cultured cancer cells. The purpose of this study was to confirm whether these particles in cytoplasm are HAP nanoparticles exactly. BEL7402 cells were incubated in HAP sol for 8 hours. Then, the cells were collected for specimen preparation. Transmission electron microscope （TEM）, energy dispersing spectrum （EDS） and electronic diffraction （ED） attached to TEM were used to detect the properties of the particles. It is found that many particles similar to HAP in shape are in the cytoplasm under TEM. By EDS analysis, they are the particles containing calcium （Ca） and phosphorus （P）. The classic rings of HAP crystal appear in the ED pictures of these particles. So the particles are confirmed as HAP nanoparticles. Thus, it is concluded that HAP nanoparticles as the crystal particles can be absorbed by hepatoma cells.     

A MEMS device for <Emphasis Type="Italic">in-situ</Emphasis> TEM test of SCS nanobeam

In-situ tensile testing in TEM (transmission electron microscopy) is a useful tool for studying mechanical properties of nano-structures because it can provide quantitative information on sample deformation at atomic scale. To facilitate in-situ TEM tensile tests of SCS (single crystal silicon) nanobeam, a MEMS tensile-testing chip was designed and fabricated. The chip was fabricated by means of bulk micromachining and wafer bonding techniques. An SCS nanobeam, a comb drive actuator, a force sensor beam and an electron beam window were integrated into the chip. With the on-chip comb-drive-actuator stretching the nanobeam and in-situ TEM observation, tensile test on a 90 nm-thick nanobeam was performed and the strain-stress relationship was obtained. The Young’s modulus was fitted to be 161 GPa and did not show the size effect. Supported by the National Basic Research (973 Program) (Grant No. 2006CB300406)     

In vitro Degradation of Butanediamine-Grafted Poly（DL-Lactic acids）

The degradation of butanediamine-grafted poly（DL-lactic acid） polymers （BDPLAs） in vitro together with PDLLA and maleic anhydride-grafted poly（DL-lactic acid） polymers （MPLAs） was investigated by observation of the changes of the pH value of incubation media, and weight loss ratio during degradation duration of 12 weeks. The results reveal that the acidity of PDLLA degradation products was weakened or neutralized by grafting butanediamine onto PDLLA. A uniform degradation of BDPLAs was observed in comparison with an acidity-induced auto-accelerating degradation featured by PDLLA and MPLAs. The biodegradation behaviors of BDPLAs can be adjusted by controlling the content of BDA. BDPLAs might be a new derivative of PDLLA-based biodegradable materials for medical applications without acidity-caused irritations and acidity-induced auto-accelerating degradation behavior as that of PDLLA.     

<Emphasis Type="Italic">In-situ</Emphasis> synthesis and characteristics of TiC−Fe cermet graded composite coating on a steel substrate

By means of an inherent elevated-temperature of poured liquid steel, a Ti-C-30 wt% Fe preform, which was pre-placed in a mould cavity, was directly ignited and a combustion synthesis reaction took place. As a result, a TiC−Fe cermet coating with a thickness of about 10 mm was simutaneously synthesized on the solidified steel matrix. The synthesized coating exhibits a feature of graded composite structure, in which both the amount and size of TiC particles decrease gradually with an increasing distance from the furface of the coating. Moreover, by a proper casting technique, the pores formed during the combustion synthesis of the preform could be centrally distributed in 2–3 mm in outer layer of the coating. When this outer porous layer was worn off, the rest coating with a thickness of about 8 mm possesses a dense structure and a high abrasive wear resistance. YAN You-wei Born in 1965 Financially supported by the National Natural Science Foundation of China (No. 50276023)     

Microstructure and thermal properties of (1−<Emphasis Type="Italic">x</Emphasis>) As<Subscript>2</Subscript>S<Subscript>3</Subscript>−<Emphasis Type="Italic">x</Emphasis>CdCl<Subscript>2</Subscript> glassy system

The homogenous glass samples of the (1−x) As₂S₃−xCdCl₂ where x=0 and 0.05 were prepared by the conventional melt-quenched method. The addition of 5 mol% CdCl₂ enhanced the glass transition temperature of pure As₂S₃ glass sample by about 30°C. Based on the experimental data, the microstructure is considered to be that the discrete molecule species of AsCl₃ and nanocrystal CdS is homogeneously dispersed in the disordered polymer network formed by AsS₃ pyramids interconnected by sulfur bridges. TAO Hai-zheng : Born in 1973 Funded by the Foundation for Excellent Youth of China.     

Effect of β-TCP Ceramic on the Total Protein of Osteoblasts

The osteoblast with the β-TCP ceramic was co-cultured. Scanning electron microscopy shows the cells adhered onto β-TCP ceramic surface and grew better, proving the β-TCP ceramic has a biocompatible property. The Coomassie brilliant blue G-250 stain shows that the total protein in the experimental groups was highly increased compared with the control group （p〈0.05）. Flow-cytometric analysis shows that β-TCP ceramic could promote the osteoblast transform from the G0/G1 phase to S phase. Those all demonstrate the product of the degradation of the β-TCP ceramic may take part in the protein metabolism of osteoblast.     

Thermochemical Study of Mixed Ligand Complexes of Rare Earths with Glycine and L-alanine

In order to obtain the standard molar enthalpies of formation of Rare-Earth amino acid coordination compounds, precise isothermal solution-reaction calorimetric method was used. The value of Δ_rH _m ^Θ of two coordination reactions was determined at T=298.2 K. From the experimental results and other auxiliary values, the standard molar enthalpies of formation of Ln(Gly)_5/2(Ala)_3/2(ClO₄)₃·H₂O(s) [Ln=La, Yb] at T=298.2 K were obtained. The values of them is to be Δ_rH _m ^Θ [La(Gly)_5/2(Ala)_3/2(ClO₄)₃·H₂O(s)]=−3545.45 kJ/mol and Δ_rH _m ^Θ [Yb(Gly)_5/2(Ala)_3/2)(ClO₄)₃·H₂O(s)]=−3793.81 kJ/mol, respectively. QU Jing-nian: Born in 1954 Funded by the Teaching and Research Award Program for Outstanding Young Professors in High Education Institute, Ministry of Education, P. R. China     

Structure and Electric Properties of （1-x）（Bi1/2Na1/2） TiO3-xBaTiO3 Systems

The structural, dielectric and piezoelectric properties of （1-x）（Bi1/2Na1/2） TiO3-xBaTiO3 ceramics were investigated for the compositional range, x=0.02, 0.04, 0.06, 0.08, 0.10. The samples were synthesized by a conventional solid-state reaction technique. All compositions show a single perovskite structure, and X-ray powder diffraction patterns can be indexed using a rhombohedral structure. Lattice constants and lattice distortion increase while the amount of BaTiO3 increases. The X-ray diffraction results show the morphotropic phase boundary （MPB） of （1-x）（Bi1/2Na12） TiO3-xBaTiO3 exists in near x=0.06-0.08. Temperature dependence of dielectric constant eT33/ε0 measurement reveals that all compositions experience one structural phase and two ferroelectric phases transition below 400℃： rhombohedral （or rhombohedral plus tetragonal） ferroelectric phase ←→ tetragonal antiferroelectric phase ←→ tetragonal paraelectric phase. Relaxor behaviors exist in the course of ferroelectric to antiferroelectric phase transition. Dielectric and piezoelectric properties are enhanced in the MPB range for （ 1-x）（Bi1/2Na1/2）TiO3-xBaTiO3.     

Microstructure and Thermal Properties Analysis of （1-x）As2S3-x CdBr2 Glass System

The homogeneous glass sample for the ( 1 - x ) As2S3-xCdBr2, where x=0. 015,0. 035,0.05, was prepared by the conventional melt-quenched method. Amorphoas ( 1 - x ) As2S3-xCdBr2 alloys were determined by X-ray diffraction, thermal compreheasive analysis and Raman scattering. The glass transittion temperature (TR) deereases a bit with the addition of CdBr2 . Based on the experimental data, the microstrtucture is considered to be the discrete molecule species of AsBr3 and Cd - S atomic bonds or clusters are honigeneously dispersed in a disordered polymer network formed by AsS3 pyramids interlinked by sulfur bridges.     

Fuzzy Modeling of Prediction Ms Temperature for Martensitic Stainless Steel

A method of fuzzy modeling based on fuzzy clustering and kalman fitering was proposed for predicting m temperature form chemical composition for martensitic stainless steel.the membership degree of each sample was calculated by the fuzzy clustering algorithm ,kalman filtering was used to identify the conseprent parameters only grade 95 steel are available for training and validation,and the fuzzy model is palid for the fol lowing element concetration ronges(wt%)Compared with that of several empirical models reported.the accuracy of the fuzzy model was almost 5 times higer than that of the best empirical model.furthernore.the coyxsitional dependences of ms were successfully determined and compared with those of the empirical formulae,it was found that the spcific element deperdeces were a function of the overall composition,,something could not easily be found using conventional statistics.     

Dielectric Behavior of BaTiO3／ PVDF Nanocomposites In-situ Synthesized by the Sol-Gel Method

BaTiO3/ PVDF nanocomposites were prepared via in-situ growth of nanosized BaTiO3 particles in PVDF matrix by using the sol-gel method. The present elements of BaTiO3/ PVDF nanocomposites were analyzed by an electron probe X-ray microanalyser. Nanosized BaTiO3 grown in the composite films was characterized by an X-ray diffractometer and a transmission electron microscope, and the dielectric properties of the composite films were measured. The distribution of BaTiO3 nanoparticles in-situ grown in the PVDF matrix was examined using a scanning electron microscope.     

Thermochemical studies of the toxic action of heavy metal ions on<Emphasis Type="Italic">Escherichia coli</Emphasis> by microcalorimetry

By using an LKB2277, BioActivity Monitor (heat conduction microcalorimeter), stopped-flow method, the thermogenetic curves of Escherichia coli growth at 37°C inhibited by four kinds of heavy metal ions are determined, and parameters such as growth rate constants, inhibitory ratio, half-inhibitory concentration etc. were obtained. The experimental results show that heavy metal ions can inhibit Escherichia coli growth obviously, but low concentration of Cu²⁺ has a promoting action. The half inhibitory concentrations of Zn²⁺, Cd²⁺, Hg²⁺ and Cu²⁺ are 28.3, 10.9, 3.19 and 69.6 μg. mL⁻¹, respectively. Judged from the rate constant, the half-inhibitory concentration and the molecular mass, the inhibitory sequence is Hg²⁺>Cd²⁺>Zn²⁺>Cu²⁺. This microclorimetric bioassay for acute cellular toxicity is based on metabolic heat evolution from cultured cells. The assay is quantitative, inexpensive, and versatile; moreover, toxicological information can be obtained with cell from other species of interest. Li Xi: Born in 1968 Funded by the National Natural Science Foundation of China (29973030 and 30170010)