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In clinical surgery, clamping soft tissue effectively has great significance in reducing operation errors rate. The mechanical response model with time-variation in small strain condition and fitted stress-time curve was introduced utilizing the corresponding displacement principle of viscoelastic and elastic tissue in Laplace image space and linear space based on Maxwell model. The mechanical response curve of the soft tissue clamping process, the curve of the peak stress and the stable stress with the increased clamping feed rate were obtained utilizing the finite element simulation software ABAQUS. Non-invasive clamping experiment was conducted using pork liver as experimental material and mechanical response curve was measured under different clamping feed rate. The experimental result is anastomosed well with the mechanical response model. Mechanical response model proposed in this paper is significant for studying mechanical feedback of soft tissue clamping process and exploiting new type of clamping device.

Grinding induces residual stresses, which can play an important role on the fatigue of the component. In general, residual stresses in a ground surface are primarily generated due to three effects: thermal expansion and contraction during grinding, plastic deformation caused by the abrasive grains of the wheel and phase transformations due to high grinding temperature. It was found that thermal expansion and plastic deformation in the grinding process were the major causes of residual stresses. In this paper, an analysis model for the calculation of residual stresses induced by a surface grinding process on an ultrahigh-strength steel (Aermet100) workpiece is presented. Firstly, the stress distribution induces by thermal expansion was obtained base on the transient heat conduction equation and the thermal properties of Aermet100. All the calculations were based on the moving heat source solution which was modeled as a uniformly distributed, 2D heat source moving across the surface of a half-space, found in Carslaw and Jaeger. The results show that the near surface residual stress is predominantly tensile and that the magnitude of this stress increases with increasing heat flux values. Secondly, the plastic deformation caused by the abrasive grains of the wheel was simulated base on the grain-workpiece interaction. The chip formation process and the material removal mechanisms can be examined using the micro-scale approach. The results show that the residual stress induced by the grinding force itself is generally compressive which is smaller than the residual tensile stress induced by thermal stress. Therefore, the residual stress brought about by grinding operation is generally a tensile stress. This paper offers an insight into the mechanism understanding of thermal and mechanical residual stresses induced by surface grinding. Key words: grinding, residual stress, grain

AbstractMn and Sb doped-PZT (PMSZT) pyroelectric thin films have been fabricated on Si substrates for uncooled infrared detectors and thermal imaging heads. The electric properties of PMSZT thin films have been investigated. A pyroelectric coefficient p of 45 nC/cm2K, dielectric constant εrof 100, and dielectric loss tanδ of 0.01 at 25°C for the PMSZT thin films have been achieved. The PMSZT detectors exhibited high figures of merit Fvof 1768 cm2/C, and Fdof 0.048 cm3/J½at 25°C. An IR detector array with the PMSZT thin film deposited on a YBCO microbridge structure for thermal isolation has been fabricated using micromachining techniques. The PMSZT detector with an air gap between the bottom electrode and Si substrates shows a larger voltage response than that of PMSZT detector without an air gap. At a 30 Hz frame frequency, a 3 times larger voltage response of a PMSZT detector with air gap, compared to that without an air gap, has been achieved. The PMSZT detectors with the relatively flat detectivity D*, ranging from 2.5×108to 6.0×108cmHz½/W in the 2.5–19.5 μm wavelength band indicate a potential for broad band IR detectors.

The murine genes coding for insulin-like growth factor II (Igf2) and its specific receptor (Igf2r) are parentally imprinted, with exclusive expression from the paternal (Igf2) or maternal (Igf2r) gene copy. We have demonstrated that the human IGF2gene is imprinted, like its murine homologue. To examine whether the human IGF2Ris also imprinted, we used CA repeat polymorphisms of the cDNA sequence to distinguish expression from each copy. Unlike the mouse, most subjects equally expressed both gene copies. However, two out of 14 informative fetuses showed exclusive expression from the maternal gene copy. We conclude that the human IGF2Rgene is parentally imprinted, like its murine homologue, but only in a minority of individuals. This is the first direct demonstration of imprinting as a polymorphic trait, a property that had been observed in transgene methylation and predicted from the behavior of certain human tumors.

Infrared detectors consisting of thin film PbZrTiO3/YBa2Cu3O7−x oxide-heterostructures have been fabricated. The YBCO thin film used as the bottom conductive electrode significantly increases the performance of pyroelectric IR detector. Detectivity values of ∼108cm Hz12/W at room temperature have been obtained for simple heterostructure device configurations in IR-wavelength range of 1 μm to 20 μm. Reactive ion etching (RIE) has been used to etch the YBCO and the other oxide layers for the development of an air bridge structure which further reduces thermal mass and increases the operation frequency of the IR detector.