Advanced Materials Research Vol. 740

Abstract: A novel combined capacitive micromachined ultrasound transducer (CMUT) with release method was proposed and fabricated with. The combined CMUT has alternating low and high-frequency elements. Several different combined patterns of CMUTs were offered. The performances of CMUTs are strongly dependent on the geometrical properties of the single cells and their arrangement within each element as well. Finite element simulations are used for analysis, design, and optimization of CMUT cells to predict device performance. Electrostatic interactions for 3-D coupled-field simulations are also performed to help investigate the electro-mechanical properties of the CMUTs. Feasibility devices are then fabricated using chromium as a sacrificial release material. The top membrane is built using a sandwich structure to ensure the formation of large size membranes with low stress.

Abstract: Decapping is very important and essential for the MEMS failure analysis. Herein, we take a simple and environment friendly method to separate the device into MEMS and CMOS parts for CD measurements and failure analysis.

Abstract: We describe the development of apparatus for measuring of electrical conductivity and Seebeck coefficient with high precision from 85 K to 1,200 K. Electrical resistance was measured by means of four-point probe method as a function of temperature. The temperature below 400 K was measured by using type T thermocouple in vacuum system was used and from 400 to 1,200 was measured by using Type S was applied for temperature between 400 and 1200 Kelvin in an inert gas system. With the dimensions of the specimen, the electrical resistivity (ρ_T) can be obtained in the unit of microohm-centimeter (μΩ-cm) and be written in polynomial, ρT=-0.3191+6.8×10-3T-6.0×10-7 T2+8.0×10-10T3. The electrical conductivity can be obtained by taking inversion of the electrical resistivity. Seebeck coefficient (α_T ) can be calculated in microvolt per Kelvin as follows: αT=1.9653-1.49×10-2T+9.0×10-5T2-2.0×10-7T3+2.0×10-10T4-1.0×10-13T5+3.0×10-17T6 , when T is temperature in K. The Seebeck coefficient data was compared with X-ray diffraction (XRD) and X-ray fluorescence (XRF) of the specimen. The result showed that our developrd apparatus yields the same as standard method when copper with purity greater than 99 percent was employed.

Abstract: Measurement and calculation of angle is an important link in borehole inclinometer work. Although the tilt sensor adopted from volume, dropping resistance , vibration resistance and other performance indicators are good embodiment currently, Measured using instrument performance, environmental factors and technical level of operator has certain influence on the angle measurement., According to the measured data to obtain regression model of angle value through on-the-spot test to calibrate measuring angle in this paper. The value has certain measurement error, measurement error is reduced by application of actual error compensation algorithm. Theory analysis and simulation calculation shows that obtaining mean maximum is 0.13452 after compensation by this method, the results of mean maximum is 4.72104 without compensation, it shows that this method is effective.

Abstract: With the development of the urbanization, however, the torrential rain has caused a series of problems. Besides the factors of management,there are some other key factors in the design of the drain system, which effects the results of effect directly. This thesis studies optimization of rain drain from the view of design factor. By discussing the main factors, the method is tested.The result shows weights of these factors, and way to solve these problems.

Abstract: A novel Co complex Co (C₁₂H₈N₂)₂NO₃I(H₂O)₂ has been synthesized from hydrothermal reaction and the crystal structure has been determined by means of single-crystal X-ray diffraction. The Co atom is coordinated with four N atoms from two 1,10-phenanthroline and two O atoms from NO₃^-, presenting a distorted octahedron geometry. The crystal structure is stabilized by intermolecular O-H...O and O-H...I hydrogen bonds interaction.

Abstract: Dispersion stability of carbon nanotubes (CNTs) is a challenging issue in the preparation of nanocomposites. This paper reports the enhancement of dispersion stability of multiwall carbon nanotubes (MWCNTs) in four solvents using two surfactants and four polymeric dispersants. The dispersion stability of MWCNTs, in term of Instability Index, was characterized by an accelerated stability analyser. The two polymeric dispersants with ionic anchoring groups and solvent-compatible chains showed the best dispersion stability as they provide polar anchoring and steric barrier which enhance the dispersion stabilisation of MWCNTs in various solvents.

Abstract: The thermal and flame retardant properties have been studied in blocked polyurethane (BPU)/tetrabromo vinyl ester (BVE) full-interpenetrating polymer networks (full-IPNs) by simultaneous polymerization (SINs) method. The studies of thermal properties of IPNs are based on the heat deflection temperature (HDT) and vicat softening temperature (VST). Results show the HDT and VST of IPNs decreased with increasing BPU content. In the meantime, the HDT and VST of BPU/BVE IPNs with filler (kaolin) are better than that of without the filler. The studies of flame retardant properties of IPNs are based on limited oxygen index (LOI) and UL-94. The IPNs showed the excellent flame retardant properties when the IPNs decreased the BPU content.

Abstract: In this paper, natural frequencies of laminated composite plates were studied. The layerwise finite element model is imposed to determine the natural frequencies of laminated composite plates. The effects of panel orientation angle, elastic modulus ratio and width-depth ratio on the natural frequencies of the laminated composite are then discussed. With an example of a sixteen-laying laminated plate, the numerical simulations show that the factor of key structural parameters to the natural frequencies of the laminated composite plate is panel orientation angle and width-depth ratio.

Abstract: The title compounds 2-lactosylthio-3-alkyl/alkoxythieno [3,2-pyrimidin-4(3H)-ones 5 were synthesized after the alcoholysis reaction of protected 2-lactosylthio-3-alkyl/alkoxythieno [3,2-pyrimidin-4(3H)-ones 4 with the catalyst of ammonia water. The latters were synthesized from the materials ethyl 3-aminothiophene-2-carboxylate 1 and alkyl/arylisothiocyanates through the thiourea intermediaters 2 and heterocyclic compounds 3. Structural characterization of the target compounds were researched and their biological activity evaluation were underway in our laboratories.