Advanced Materials Research Vol. 741

Abstract: This study intends to investigate experimentally the mechanical characteristics of the compressive strength and elastic modulus of concrete using 3 types of binder that are ordinary Portland cement, fly ash and physically milled fly ash. The test results show that the compressive strength and elastic modulus of the cement-zero concrete reached respectively 30.0 MPa and 19.1 GPa, and indicated that more than 90% of the strength was developed at early age. In addition, a comparison of the geopolymer concrete with ordinary concrete enabled to derive and suggest formulaeexpressing the elastic modulus in function of the compressive strength.

Abstract: The removal of Cu²⁺ ions from aqueous solution was studied using pickled diatomite samples. The linear Langmuir and Freundlich adsorption equations were applied to describe the equilibrium isotherms. The pseudo-first-order and pseudo-second-order models were used to determine the kinetic data. The experimental data were well fitted by the pseudo-second-order kinetic model.

Abstract: The thickness dependent direct current electrical conduction mechanism in plasma polymerized pyrrole (PPPy) monolayer thin films has been discussed in this paper. A parallel plate capacitively coupled glow discharge reactor was used to deposit PPPy thin films at room temperature onto glass substrates. The Fourier Transform Infrared (FTIR) analyses showed that the spectrum of PPPy is very much different than that of the pyrrole monomer and indicated that the monomer has undergone the re-organization during the plasma polymerization. The current density-voltage (J-V) characteristics of PPPy monolayer thin films of different thicknesses indicated an increase in electrical conductivity in the thin films of lower thickness. It is seen that in the low voltage region, the current conduction obeys Ohms law while the charge transport phenomenon appears to be the space charge limited conduction (SCLC) in the higher voltage region. The permittivity, free charge carrier density, and the mobility of the charges of the PPPy monolayer thin films have been calculated from the experimental data of J-V characteristics and found to be 1.07 × 10^-10 C²N^-1m^-2, (3.56 ± 0.01) × 10²² m^-3, (4.4 ± 0.01) × 10^-19 m² V^-1s^-1 respectively.

Abstract: Total hip prosthesis (THP) is the most success of the 20^th century in orthopaedic biomedical engineering. However due to difficult conditions within the human body its durability is generally limited to 15-16 years. THP is a bio-tribosystem, on which many mechanical, thermal, chemical and biological factors act. This paper presents the results of an analysis regarding the topography and tribological parameters of femoral heads structures before and after TiN coating. We report on the synthesis of TiN thin films on steel substrates by pulsed laser deposition (PLD) method for improving the mechanical characteristics of the structures. Adhesion resistance of the coating on the sub-layer was evaluated by scratching tests accompanied by Optical Microscopy (OM), Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). As a principal result, this work points out that TiN protective coatings deposited by PLD technique with the maximum number of pulses can represent an alternative technology to ensure adhesion and scratch resistance of TiN coatings on femoral heads.

Abstract: In recent years, the appreciation of cellular heterogeneity instead of cell information inferred from population-level data has driven the development of single-cell techniques. Among those adopted in this research were AFM characterization, fluorescence technique and a self-developed cell-targeting process in order to correlate precisely the cells early or late apoptotic stage with its corresponding morphology status, the membrane roughness in this paper. Research results were compared to results revealed from our previous research for the effectiveness verification of the proposed scheme.

Abstract: Mechanical properties of nanolayered materials were simulated using molecular dynamics method. Elastic modulus was especially focused in this study, and the effect of layer width and the interval of the layers on the deformation behavior were discussed. Tension was imposed by adding a mono-axial strain in the x direction at a constant rate, while the other two normal components of stress were controlled to be zero. The influence of the dimension was preliminarily checked to avoid the model-size dependency, and the suitable size was determined as a cube with 12 unit cells in the x, y and z directions. First, a single nanolayer was set in the model, and the layer width was varied. The obtained elastic modulus showed almost linear dependency with the layer width. Then the interval of the layer was varied, and it revealed that the elastic moduli depend on the cross-sectional ratio of the layered material rather than the layer interval.

Abstract: Titania nanotubes (TiO₂ NTs) working electrodes for hydrogen production by photoelectrocatalytic water splitting were synthesized by means of anodization method. The electrolytes were the mixtures of oxalic acid (H₂C₂O₄), ammonium fluoride (NH₄F), and sodium sulphate (VI) (Na₂SO₄) with different pHs. A constant dc power supply at 20 V was used as anodic voltage. The samples were annealed at 450 °C for 2 hrs. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) were used to characterized TiO₂ NTs microstructure. TiO₂ NTs with diameter of 100 nm were obtained when pH 3 electrolyte consisting of 0.08 M oxalic acid, 0.5 wt% NH₄F, and 1.0 wt% Na₂SO₄ was used. Without external applied potential, the maximum photocurrent density was 2.8 mA/cm² under illumination of 100 mW/cm². Hydrogen was generated at an overall photoconversion efficiency of 3.4 %.

Abstract: A superabsorbent hydrogels were synthesized by an optimized rapid solution polymerization of concertrated partically neutralized acrylic acid in the presence of an organic crosslinker agent under normal atmospheric conditions, nanosized SiO₂ spheres were added into gels to strengthen the gels and decrease the cost. The results showed that, comparing to the inorganic-free hydrogels, the addition of SiO₂ spheres cause a sligtly decreased swelling ratio with a faster swelling rate. Meantime, the strength of hydrogels increases 10-20%.

Abstract: The thermodynamic performances of solar assisted CO₂ vapor compression heat pump cycles with an ejector are analyzed and compared with that of conventional CO₂ heat pump cycle (named as A cycle). Under the given working conditions, the COP of solar assisted CO₂ heat pump cycle with an ejector after compressor cycle (named as C cycle) is much higher than that of CO₂ heat pump cycle with an ejector before compressor cycle (named as B cycle) and that of the A cycle because of the lower compressor power of the C cycle. The compressor volume displacement of the C cycle demanded for providing the same heat capacity of gas-cooler is the lowest among the three cycles. So the compressor size of the C cycle is very small and the cost of the C cycle is very less. In the area having rich solar energy resource, it is significant to employ the C cycle for providing space heating by optimizing design ejector and selecting compressor, thus, the performances for this C cycle can be improved greatly. In the area not having rich solar energy resource, the B cycle can be used for providing space heating; the performances can also be improved accordingly.

Abstract: For the reason of high failure rate of car battery and car electric generator, an on line car battery monitor base on Altera FPGA/CPLD chip MAX serials was realized, which combining with the AD collection and power handling technology. The equipment can monitor the voltage, quantity, current leakage of the battery and the electric generator failure. It can make judgment of battery performance and has a good application value.