Dynamic tensile properties of carbon fiber composite based on thermoplastic epoxy resin loaded in matrix-dominant directions

The dynamic tensile properties of carbon fiber (CF) composite loaded in the matrix-dominant direction are experimentally determined. In this study, thermoplastic epoxy resin is used as a matrix of the CF composite. A dynamic tensile test is performed using a tension-type split Hopkinson bar technique. The experimental results show that there are not linear relationships between tensile strength and strain rate in case of the 10°, 30° and 45° specimens, although the tensile strength of CF composite, whose matrix is typical thermosetting epoxy resin, linearly increases with the strain rate for all fiber orientation angles. From the fracture surface observation, it is found that the ductile fracture of the matrix can be observed only when 10° off-axis specimen is tested under dynamic loading condition. It is inferred that the softening of the thermoplastic epoxy resin in the vicinity of interface area takes place with increasing strain rate.     

Influence of high growth rates on evaporated Cu(In,Ga)Se2 layers and solar cells

Thin film solar cells based on polycrystalline Cu(In,Ga)Se₂ were prepared by elemental co‐evaporation using modified three‐stage processes on soda lime glass substrates at a low substrate temperature of 450°C intended for application on polyimide foils. The growth rates in the different stages of the growth process were varied, and it was observed that the final composition profile and structural quality of the film are mainly determined by the growth rate in the third stage. Application of high growth rates in the second stage was found to have no significant impact on layer morphology and gallium grading profile, which was confirmed by scanning electron microscopy, secondary ion mass spectroscopy, and x‐ray diffraction measurements. On the other hand, scanning electron microscopy cross sections revealed that high growth rates in the third stage lead to a fine‐grained structure toward the surface as well as smaller grains toward the back contact. Secondary ion mass spectroscopy and x‐ray diffraction measurements of such layers revealed a pronounced gallium grading profile, while Raman spectroscopy showed strong occurrence of group III‐rich phases in the near‐surface region. The final device performance was found to deteriorate by about 10% relative to the baseline process efficiency when growth rates of up to 500 nm min⁻¹ were applied in the second stage or 600 nm min⁻¹ in the third stage. Copyright © 2011 John Wiley & Sons, Ltd.     

A level set‐based topology optimization method targeting metallic waveguide design problems

In this paper, we propose a level set‐based topology optimization method targeting metallic waveguide design problems, where the skin effect must be taken into account since the metallic waveguides are generally used in the high‐frequency range where this effect critically affects performance. One of the most reasonable approaches to represent the skin effect is to impose an electric field constraint condition on the surface of the metal. To implement this approach, we develop a boundary‐tracking scheme for the arbitrary Lagrangian Eulerian (ALE) mesh pertaining to the zero iso‐contour of the level set function that is given in an Eulerian mesh, and impose Dirichlet boundary conditions at the nodes on the zero iso‐contour in the ALE mesh to compute the electric field. Since the ALE mesh accurately tracks the zero iso‐contour at every optimization iteration, the electric field is always appropriately computed during optimization. For the sensitivity analysis, we compute the nodal coordinate sensitivities in the ALE mesh and smooth them by solving a Helmholtz‐type partial differential equation. The obtained smoothed sensitivities are used to compute the normal velocity in the level set equation that is solved using the Eulerian mesh, and the level set function is updated based on the computed normal velocity. Finally, the utility of the proposed method is discussed through several numerical examples. Copyright © 2011 John Wiley & Sons, Ltd.     

Heaviside projection based topology optimization by a PDE-filtered scalar function

This paper deals with topology optimization based on the Heaviside projection method using a scalar function as design variables. The scalar function is then regularized by a PDE based filter. Several image-processing based filtering techniques have so far been proposed for regularization or restricting the minimum length scale. They are conventionally applied to the design sensitivities rather than the design variables themselves. However, it causes discrepancies between the filtered sensitivities and the actual sensitivities that may confuse the optimization process and disturb the convergence. In this paper, we propose a Heaviside projection based topology optimization method with a scalar function that is filtered by a Helmholtz type partial differential equation. Therefore, the optimality can be strictly discussed in terms of the KKT condition. In order to demonstrate the effectiveness of the proposed method, a minimum compliance problem is solved.     

Mucosal ulcerogenic action of monochloramine in rat stomachs: effects of polaprezinc and sucralfate

Effects of a novel zinc compound polaprezinc [N-(3-aminopropionyl)-L-histidinatozinc] and sucralfate on the mucosal ulcerogenic responses induced by monochloramine (NH2Cl) were examined in rat stomachs. Oral administration of NH2Cl (>60 mM) produced severe lesions in unanesthetized rat stomachs, with concomitant increase of lipid peroxidation. These lesions were aggravated by sensory deafferentation but not affected by pretreatment with indomethacin or L-NAME. The mucosal ulcerogenic response to NH2Cl was significantly inhibited by oral pretreatment with either dmPGE2 (10 microg/kg), capsaicin (30 mg/kg), or NOR-3 (3 mg/kg), the NO donor. Gastric lesions induced by NH2Cl were also inhibited by prior oral administration of polaprezinc (3-30 mg/kg) as well as sucralfate (30 and 100 mg/kg). The protective effect of polaprezinc was not affected by any pretreatments such as indomethacin, L-NAME, or sensory deafferentation, while that of sucralfate was significantly mitigated in the presence of either indomethacin or L-NAME. On the other hand, mucosal exposure to NH4OH (60 mM) caused a marked PD reduction in ex vivo stomachs made ischemic by bleeding from the carotid artery, followed by severe gastric lesions. These ulcerogenic and PD responses caused by NH4OH plus ischemia were also attenuated by prior application of polaprezinc, while dmPGE2 and sucralfate prevented such lesions without affecting the reduced PD response. These results suggest that: (1) NH2Cl generated either exogenously or endogenously damages the gastric mucosa, (2) both polaprezinc and sucralfate protect the stomach against injury caused by NH2Cl, and (3) the mechanisms underlying the protective action of sucralfate may be partly mediated by both endogenous PGs and NO but may be different from those of polaprezinc.     

Age-dependent changes of mineral contents in men and women''s calcanei

Damage to posterior parietal cortex in humans is known to cause hemineglect, and specifically difficulty in disengaging attention in tests of covert orienting. Aspirative lesions of a region of cortex in rats which is thought to be homologous to primate posterior parietal cortex has also been reported to cause what appears to be multimodal neglect. In order to make an assessment of the nature of this disorder, a variety of tests were employed: (1) a test of somatosensory neglect after Schallert et al. (Pharmacol. Biochem. Behav., 16 (1982) 455-462); (2) a skilled paw-reaching test after Whishaw et al. (Brain 109 (1986) 805-843); (3) a visual reaction time task with peripheral cues analogous to Posner's test of covert orienting (Q. J. Exp. Psychol. 32 (1980) 3-25). Following the posterior parietal lesion there was a global increase in reaction time of responses made contralateral to the lesion in the reaction time task, but there was no evidence of a deficit in covert orienting. There was also no evidence of somatosensory neglect. There was a decrease in the number of attempted reaches which the contralateral paw and a tendency to spend a smaller proportion of time in the contralateral half of the reaching cage.     

Age-independent constancy of mineral contents in human vertebra and auditory ossicle

To elucidate age-related changes of mineral contents in human bones, element contents of human vertebrae and auditory ossicles were determined by inductively coupled plasma atomic-emission spectrometry. The cervical, thoracic, and lumbar vertebrae were removed from 12 vertebral columns. The mallei of auditory ossicle were removed from 27 cadavers. It was found that average relative contents (RCs) of calcium and phosphorus in cervical, thoracic, and lumbar vertebrae remained almost constant within ages ranging from 46 to 99 y. In addition, it was found that the RCs of calcium and phosphorus in men's and women's mallei remained constant within ages ranging from 40 to 98 yr. These results support the view that there is no significant age-dependent change of mineral contents in human bones.     

Hemorrhage exerts different effects on variabilities of heart rate and blood pressure in dogs

The aim of the present study was to evaluate the effects of hemorrhage on heart rate variability (HRV) and blood pressure variability (BPV) as indicators of autonomic nervous system (ANS) and hypovolemia. We induced hemorrhagic hypovolemia in 7 dogs by removing blood in graded stages (0%, 10%, 20%, 30%, 40% of the estimated blood volume; EBV). HR was unchanged during hemorrhage, while mean BP decreased significantly after 30% EBV hemorrhage. Low frequency component (LF: 0.04-0.15 Hz) of HRV significantly increased after 20% EBV hemorrhage but high frequency component (HF: 0.15-0.4 Hz) of HRV was not altered. LF of BPV increased significantly stepwise after 20% EBV hemorrhage and HF of BPV increased significantly after 30% EBV hemorrhage, showing that both LF and HF of BPV might indicate the degree of hypovolemia. During hemorrhage LF of HRV and BPV increased and HF of HRV was unchanged, indicating the shift of the autonomic balance toward sympathetic dominance. An excellent quantitative correlation between LF of BPV and the degree of hypovolemia was demonstrated during graded hemorrhage, while LF of HRV plateaued at its maximum value at 20% EBV hemorrhage. In conclusion, our study suggests that the spectral analysis of HRV and BPV during graded hemorrhage shows different characteristics in the quantitative evaluation of ANS and hypovolemia.     

Electro-thermal-mechanical computations in ZnO arrester elements

Transient, nonlinear finite element analysis with coupled thermal and electric fields is employed to compute the electric and thermal field distributions in ZnO arrester elements, including both nonlinear electrical and nonlinear thermal properties. Mechanical stress in the element is computed during post processing, based on the thermal field. The data indicate that a metallic protrusion from the sprayed electrode into the ZnO can cause substantial temperature rise in a microscopic region around the defect. The effects of a delamination between the electrode and the ZnO surface are less severe. Statistical computations have been undertaken to explore the effect of nonconducting grains on the disk conduction threshold voltage and disk nonlinearity. The computations yield similar results to those in the literature based on nonlinear circuit equations but are much less time consuming     

Pretreatment with topical 60% lidocaine tape reduces pain on injection of propofol

We determined whether pretreatment with topical 60% lidocaine tape reduced the incidence of pain on injection of propofol compared with mixing intravenous lidocaine with propofol. In a randomized, double-blind trial, 90 patients were allocated to one of three groups: pretreatment with a bioocclusive dressing and administration of a premixed solution of propofol 180 mg and 2 mL of normal saline (Group A); pretreatment with 60% lidocaine tape and a premixed solution of propofol and normal saline (Group B); or pretreatment with a bioocclusive dressing and a premixed solution of propofol 180 mg and lidocaine 40 mg (Group C). The incidences of pain in Groups A, B, and C were 86.7%, 33.4%, and 20%, respectively. Group B and Group C had a significantly lower incidence of pain than Group A. There was no significant difference in the incidence of pain between Group B and Group C. There was no significant difference in the distribution of site of pain on injection of propofol among the three groups. Pretreatment with topical 60% lidocaine tape reduced the incidence of pain on injection of propofol similar to that of intravenous lidocaine mixed with propofol. IMPLICATIONS: Pretreatment with topical 60% lidocaine tape reduces the pain associated with injection of propofol, a frequently used intravenous anesthetic. This approach should increase patient comfort during induction of anesthesia.