Oxygen and nitrogen adsorption in single-walled carbon nanotube (SWCNT) is studied by density function and discrete variational (DFT-DVM) method. The models of O2 and N2 adsorption in the SWCNT are optimized based on the energy minimization. The calculated results of density of state, populations and energy gaps of the molecular orbitals show that oxygen adsorption in SWCNT increases the carbon nanotube’s electrical conductivity more notably than nitrogen adsorption, which is consistent with the experiment.
Poly (ethylene axide) (PEO) modified WO3 thin films were prepared on glass substrates with special temperature. The sol-gel transition proess was investigated by using DTA-TG, SEM and XRD. The electrochemical characteristic of the films was studied by cyclic voltmmetry measurement. The results show that PEO has heavy effects on the crystallization of WO3 during structure evolution because of the interaction between PEO and WO3. It increases the crystallization temperature of the gels and thus improves the electrochemical properties and cyclic life of WO3 film as electrochromic materials.
Highly ordered multiwalled carbon nanotube arrays were fabricated by pyrolysis of acetylene within anodic alumina templates. Nanotubes are very uniform in diameter and open at both ends. High resolution transmission electron microscopy and electron diffraction analysis show that the carbon nanotubes are well graphitized. These standing and open carbon nanotubes are possible to offer a potential elegant technique for electron emitting devices, chemical functionalization and nanotube composites.
The anion-kaolinite surface interactions and AuS− adsorption onto the surfaces of kaolinite were studied using the self-consistent-field discrete variation (SCF-Xα-DV) method. Electronic structure and energies of the system of anion AuS− adsorbed on an atomic cluster of kaolinite were calculated. The results show that the systems with lower total energy are those AuS− adsorbed on the edge surfaces, which indicates that the systems of adsorption of AuS− on the edges are more stable relative to those adsorbed on the basal plane. On the other hand, bond order data suggest that significant shifting of atomic charge and the overlapping of electronic cloud between Au (I) of the AuS− and the surface ions of kaolinite would take place in the systems with AuS− being adsorbed on the edges, especially at the site near Al octahedra. Therefore, it can be concluded that edge sites will dominate the complexation reactions of the surfaces of kaolinite, with negligible contributions from other functional groups on the basal plane, which are dominated by either siloxane sites in silica layers or aluminol sites in gibbsite layers.
A high alkali reactive aggregate-zeolitization perlite was used to test the long-term effectiveness of LiOH in inhibiting alkali-silica reaction. In this paper, the rigorous conditions were designed that the mortar bars had been cured at 80°C for 3 years after autoclaved 24 hours at 150°C. Under this condition, LiOH was able to inhibit the alkali-silica reaction long-term effectiveness. Not only the relationship between the molar ratio of n (Li)/(Na) and the alkali contents in systems was established, but also the governing mechanism of such effects was also studied by SEM.
Partially stabilized zirconia ceramics were sintered using fine powder of ZrO2-3 mol% Y2O3 prepared by the chemical co-precipitation method. The tetragonal-to-monoclinic phase transformation in ZrO2 ceramics during the aging in boiling water and the effect of an applied stress of 100MPa were mainly investigated. The degradation of ZrO2 ceramics is considered to be caused by the reaction between Y2O3 and H2O, which leads to a decreasing in the stability of tetragonal phase of ZrO2. It is found that the tensile stress improves the driving force of the phase transformation and accelerates the degradation while the compressive stress has no obvious effect on the degradation.
The effect of operating conditions on the aluminium content of Ni-Al alloy deposit and the catalytic function of NaF on electrodeposition in the nonaqueous solution containing aluminium are investigated. The results indicate that the plated aluminuim content will be increased with the rise of current density in a given range. When the current density is 2.5A/dm2, nickle-aluminium alloy containing 13.1 wt% aluminium will be deposited. The plated aluminium content will be increased by 2wt% as 0.1 mol/L NaF is added to the bath.
A new niobate Ba3NaBiNb10O30 was synthesized by the solid state reaction. The reaction mixture was characterized by thermogravimetric and differential thermal analysis (TG-DTA), X-ray diffraction and dielectric constant measurements. The results show that Ba3NaBiNb10O30 has an orthorhombic tungsten bronze structure with space group Cmm2 and the unit cell parameters are a=1.7660(1) nm, a=1.7626(1) nm, c=0. 78621(6) nm, Z=4. Ba3NaBiNb10O30 undergoes two phase transitions at 200°C and 400°C, respectively.
A high-Fe containing aluminum matrix filler metal for hardfacing aluminum-silicon alloys has been developed by using iron, nickel, and silicon as the major strengthening elements, and by measuring mechanical properties, room temperature and high temperature wear tests, and microstructural analysis. The filler metal, which contains 3.0%–5.0% Fe and 11.0%–13.0% Si, exhibits an excellent weldobility. The as-cast and as-welded microstructures for the filler metal are of uniformly distribution and its dispersed network of hard phase is enriched with Al-Si-Fe-Ni. The filler metal shows high mechanical properties and wear resistance at both room temperature and high temperatures. The deposited metal has a better resistance to impact wear at 220°C than that of substrate Al-Si-Mg-Cu piston alloy; at room temperature, the deposited metal has an equivalent resistance to slide wear with lubrication as that of a hyper-eutectic aluminum-silicon alloy with 27% Si and 1% Ni.
A new niobate Ba5BiTi3Nb7O30 was synthesized by the solid-state reaction. It was characterized by X-ray diffraction and dielectric constant measurements. The results show that Ba5BiTi3Nb7O30 is paraelectric at room temperature and belongs to tetragonal 4/mmm symmetry with unit cell parameters a=1.25020 nm, c=0.39704 nm. Ba5BiTi3Nb7O30 has only one phase transition, paraelectric to ferroelectric, below 0°C.
Adhesion strength is an important target in evaluating the quality of coating layers. The traditional way of adhesion strength test is bonding pull-off method for thick layers and scratch test for thin films. The drawbacks of these two methods are discussed in this paper, and an evaluating method for adhesion strength of coating by burying beforehand specimen is proposed. The adhesion strength of samples is measured with two methods. The dispersity of testing data is lower than that in the ASTM-C663-79 Standard.
Needle-like hydroxyapatite crystals were synthesized by homogeneous precipitation method with water-soluble calcium salts and phosphates. The work focuses on the analysis of influencing factors on length and lengh/diameter ratio of hydroxyapatite crystals, which are main characteristics of reinforcement materials. The effects caused by system temperature, concentration of nutrient, and additives are discussed, and the optimum reacting condition is given.
Polycrystalline bulk Ti3SiC2 material with a high purity and density was fabricated by spark plasma sintering from the elemental powder mixture with starting composition of Ti3Si1−xAlxC2, where x=0.05–0.2. X-ray diffraction patterns and scanning electron microscopy photographs of the fully dense samples show that a proper addition of aluminum promotes the formation, and accelerates the crystal growth rate of Ti3SiC2, conse-quently results in a high purity of the prepared samples. The synthesized Ti3SiC2 is in plane-shape with a size of about 10–25μm in the elongated dimension. Solid solution of aluminum decreases the thermal stability of Ti3SiC2, and lowers the temperature of Ti3SiC2 decomposeing to be 1300°C.
Nano fluorescent powder of Y4Al2O9: Eu3+ was synthesized by sol-gel method. The XRD shows that the product prepared at 900°C is pure-phase Y4Al2O9: Eu3+. The Y4Al2O9 powder is nano-size crystal testified by BF and ED analysis of TEM. The grain diameter of Y4Al2O9 is in the range between 20 and 50nm, and its average is 30 nm. The luminescent spectra show that Eu3+ ious occupy two kinds of sites in Y4Al2O9 crystal lattice. One is in the strict inversion center, and the other is in off lying inversion center. When excited with UV light (λ=254nm), Y4Al2O9: Eu3+ exhibits an orange emission bond at λ=590 nm due to the5Do→7F1 transition and a red emission band at λ=610 nm due to5Do→7F2 transition.
MEM (model element method) is proposed to resolve the present difficulties and problems in CAE about plastic forming of material. There are four advantages when MEM is integrated with FEM (finite element method) and UBM (upper boundary element method). First, it can make full use of their own advantages and overcome their own disadvantages; second, it can analyse material plastic fluid expediently; third, it can optimize design; finally, it can improve technological content and application effect of CAE software. Based on introducing the principle of MEM briefly, features and applications of MEM are pointed out. In conclusion, a new analysis method for plastic forming comes forth.
LiMn2O4−xFx 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.
Effects of titanium oxide (TiO2) nanoparticles on Bel-7402 human hepatoma hepatoma cells and L-02 human hepatocytes at different times were observed. Using cell culture, cell growth curves of Bel-7402 cells and L-02 cells treated with TiO2 nanoparticles were examined by MTT assay, and the cellular ultrastructure was observed by an analytical transmission electron microscope (ATEM). It is found that OD value of Bel-7402 cell treated with TiO2 nanoparticles for 48–144h is obviously lower than that of control group (p<0.01). However the growth curve of L-02 cells is almost not affected by TiO2 nanoparticles. ATEM and energy dispersive X-ray (EDX) analyses show that there are obvious vacuoles increased heterolysosome, and particles with high electron density which are confirmed to be TiO2 nanoparticles in Bel-7402 cytoplasm. More interestingly, it is alse found that TiO2 nanoparticle obviously inhibits the proliferation of hepatoma cells by altering lysosome activity and destroying cytoplasm structure. The inhibition on proliferation of hepatocytes by TiO2 nanoparticles is much slighter. The results demonstrate that TiO2 nanoparticle has different killing effects on cancer cell and normal cell.
The solidifying effect of cement addition on municipal solid waste incineration fly ash (MSWFA for short, collected from the gas exhaust system of MSW incinerator), the interaction of MSWFA with cement and water and the leaching of heavy metals from cement-solidified MSWFA are investigated. The main results show that: (1) when MSWFA is mixed with cement and water, H2 evolution, the formation and volume expansion of AFt will take place, the volume expansion can be reduced by ground rice husk ash addition; (2) heavy metals do leach from cement-solidified MSWFA and at lower pH more leaching will occur; (3) compared with cement—solidified fly ash, the leachate of solidified MSWFA is with higher heavy metal contents; (4) with the increment of cement addition leached heavy metals are decreased; and (5) concentrations of Zn, Mn, Cu and Cd in all the leachates can meet the relevant Standards of Japan, but as the regulations for soil and groundwater protection of Japan are concerned, precautions against the leaching of Pb, Cl− and Cr6+ and so on are needed.
The workability, mechanical and physical properties are investigated, based on the requirements of the high properties of polymer cement concrete (PCC). The research results reveal that PCC is greatly improved and strengthened by adding appropriate polymer. At polymer/cement=0–0.15, its porosity decreases greatly due to the improved pore structure. The weak area at interface is strengthened. The workability, mechanical and physical properties are obviously enhanced with the proportion of polymer and cement. At the same time the properties are much improved under the adequate curing conditions and admixture (0–10%).
An experimental study is carried out on fatigue defect of layer steel fiber reinforced concrete (LSFRC). Based on experimental data, the various relation curves are given corresponding to different stress levels 0.9, 0.85, and 0.8. Furthermore, the fatigue defect degree is defined, and the strain-cycle ratio-equations and defect-cycle ratio equations with the correlation coefficients very close to 1, are regressed in terms of the cubic polynomial, of which the fittings are preferable. In addition, the results show that the fatigue defect of LSRC presents three-phase development regularity too. And in comparison with the plain concrete, the third phase of the fatigue defect of LSFRC is longer, therefore the fatigue failure of LSFRC is more ductile. The mechanism of the fatigue defect is discussed too.
According to the reliability of material strength, the optimal design for the cross sectional size of thin-walled box beam was studied. Firstly the cross sectional size as design random variable was determined, then its stochastic nature was researched, with which the objective function is to seek the maximum reliability of the beam under given constraint conditions. This way is not the same as the conventional optimal design for the minimum weight of the material. With establishing the optimal objective, the reliability of the material under conditions of static and fatigue was considered. The corresponding calculated expression are given. Normally the cross section sizes are fitted to the normal distribution, for the simplification of the design variable, the variation of the section size is assumed as a dependent variable proportional to the mean of the size. The way is different not only with the conventional optimal design but also with the common reliability design. The maximum reliability of material is obtained, meanwhile the are of the cross section is reduced, i. e., the weight of the material is decreased.
Nowadays asphalt pavement structure bearing is not the main subject for pursuers to study. Comparatively, the pavement performance is more important and emphasized. Based on this, rutting and cracking analysis is introduced into pavement optimization. A optimization model based on these two considerations is also established. The genetic algorithms (GAs) is adopted to solve the model. It is an intellective method. This research provides a new idea and technique for asphalt pavement structure optimization.
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.
In order to investigate detonation propagation characteristics of different charge patterns, the detonation velocities of superposition strip-shaped charges made up of a detonating cord and explosives were measured by a detonation velocity measuring instrument under conditions of different ignition. The experimental results and theoretical analysis show that the maximum detonation propagation velocity depends on the explosive materials with the maximum velocity among all the explosive materials. Using detonating cord in a superposition charge can shorten detonation propagation time and improve the efficiency of explosive energy. The measurement method of detonation propagation velocity and experimental results are presented and investigated.
The microstructures of general crumb rubber (CR), dynamic desulfurized crumb rubber (DD-CR) and high speed agitation desulfurized crumb rubber (HSADCR) modified bitumens were investigated by a fluorescence microscope, and the physical properties of these three modified bitumens were studied. The results show that the dynamic desulfuration can improve the swelling capacity of crumb rubber in bitumen by destroying the sulfuratized bond of the crumb rubber, but the reunion of rubber particles during dynamic desulfuration also makes the swelling and the DDCR in bitumen difficult, so properties of the DDCR modified bitumen are not superior to the general crumb rubber modified bitumen. However, high speed agitation desulfuration can not only improve the swelling capacity of crumb rubber in bitumen, but also avoid the reunion of rubber particles, so some properties of bitumen can be improved by the modification of HSADCR.
The compatibility between a fiber optical sensor and concrete structure in the optic fiber smart concrete is studied. The methods of improving the compatibility are proposed based on theory analysing, and a novel fiber optical sensor was developed. The experimental results show that the novel structure of fiber optical sensor and the scheme of the protecting layer of epoxy resin bed composite not only enable the sensor to be applied in strict environment, but also can monitor the beginning propagation and breaking of concrete craks. The results also indicate that the sensor will maintain its properties in the case of large deformation and that it has the high compatibility with concrete structure and con meet special needs of the intelligent materials and structure.