Quantitative surface photovoltage spectroscopy of semiconductor interfaces

A comprehensive and quantitative method for extracting the important parameters of interface states is presented. The method is based on wavelength-, intensity-, and time-resolved surface photovoltage spectroscopy, as well as on measurements as a function of the thickness of an overlayer. Data analysis provides detailed information about interface state properties, including their energy position and distribution, density, and the transition probabilities, i.e. their thermal and optical cross sections. It is also possible to distinguish between surface and bulk states, and determine the spatial site of the states in the case of a heterostructure. Experimental examples for various III-V and II-VI compound semiconductors are given.     

A novel antimicrobial peptide from the loach, Misgurnus anguillicaudatus

We investigated the effects of thyrotropin releasing hormone (TRH) on changes in cortical concentrations of acetylcholine (ACh) and monoamines produced by concussion in mice. Concussion was induced by dropping a metal rod on the head, and the concentration of ACh, norepinephrine (NE), dopamine (DA) and serotonin (5-HT) in the cerebral cortex were measured by HPLC. We also examined the arousal effects of 0.5 mg/kg of TRH and 0.015 mg/kg of L-pyro-2-aminoadipyl-histidyl-thiazolidine-4-carboxamide (MK-771), a TRH analogue, injected intraperitoneally 10 min before concussion, on neurotransmitter concentrations. Mice were sacrificed at 25 (representing the righting reflex time) and 210 s (representing spontaneous movement time). At 25 s after concussion, the concentration of ACh was significantly higher than in control mice, but pretreatment with TRH and MK-771 prevented the rise in ACh. In contrast, head injury significantly reduced NE concentration. TRH and MK-771 also prevented the fall in NE. Concussion did not change cortical concentrations of DA and 5-HT. Our results suggest that disturbances of consciousness produced by concussion may be due to increased ACh and diminished NE in the cerebral cortex. Our findings also suggest that the arousal effects of TRH on concussion-induced disturbances of consciousness are due to normalization of cortical cholinergic and noradrenergic neuronal systems.     

Thromboxane A2 receptor-specific antagonism in hypothermic cardiopulmonary bypass

Using a thromboxane A2 receptor-specific antagonist, SQ 30,741, this study was undertaken to define the role of thromboxane A2 in postischemic myocardial reperfusion injury and in the heparin-protamine reaction. Eighteen heparinized (300 units/kg) sheep were placed on cardiopulmonary bypass (CPB) after complete instrumentation, cooled to 28 degrees C, and had their aortas crossclamped for 1 hour. They were then rewarmed to 36 degrees C and weaned from CPB without inotropic support. Control sheep (n = 6) received a saline infusion throughout the procedure. Bolus animals (n = 6) received 5 mg/kg of SQ 30,741 at 5 minutes after discontinuation of CPB and before protamine sulfate administration. Infusion animals (n = 6) received an SQ 30,741 bolus of 5 mg/kg followed by a continuous infusion of 5 mg.kg-1 hr-1 of SQ 30,741 initiated before CPB. All animals received 5 mg/kg of protamine sulfate over a 15-second period 15 minutes after being weaned from CPB. Control animals exhibited significantly decreased global myocardial function after the 1-hour ischemic interval. Further significant functional decline and increase in pulmonary pressure occurred after protamine sulfate administration. Bolus animals experienced a similar postischemic injury, but had no further decrease in function following protamine infusion. Infusion animals had significantly improved global myocardial function after bypass compared with both other groups and were also protected from the deleterious effects of protamine sulfate administration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of process and product parameters on the shape of nanosecond pulses used in high-field liquid food treatment

Many industrial applications like high-field food sterilization require short-duration fast-rise-time high-voltage pulses. Measurement of such narrow steep-front high-voltage pulses are always difficult, considering the potential levels and the time scales involved. In addition, by nature, liquid foods are highly conductive, hence, any small change in circuit inductance has substantial influence on the measured pulse. Further, the oscillations introduced by the circuit parameters influence the voltage magnitude and the effective treatment time. Hence, these points must be taken into account while computing the total treatment time and the energy actually spent, as these parameters influence the kinetics of food processing. In this paper, the effects of load impedance, the circuit inductance, and the location of the probe position that influence the shape of the measured pulse with liquid foods as load are discussed. It has also been shown that knowing the low-voltage conductivity of the food to be treated, and with a realistic estimation of circuit inductance, it is possible to predict the shape of the pulse under different test conditions using PSPICE circuit models.     

Nonuniform RF Overstress in High-Power Transistors and Amplifiers

Nonuniform light emission from power transistors at 2-3-dB compression levels has been imaged using a microscope- mounted camera. The nonuniformity depends on the device lateral geometry, load impedance, dc and radio frequency (RF) conditions, and the negative gate current, which is a result of the RF-induced impact ionization in the transistors. Numerical simulations demonstrated a nonuniform distribution of the RF overstress in the transistors under the same conditions. The simulations indicate that the nonuniformity in the light intensity may be attributed to the RF-induced voltage overstress. Therefore, the observed light emission may be used as a direct and contactless monitor of the RF-induced overstress in transistors and power amplifiers.     

Effects of distal cement voids on cement stress in total hip arthroplasty

Studies done by Médecins du Monde indicate that sanitary exclusion is a growing phenomenon in France, children included. Paediatricians must be concerned by this phenomenon, which is related to the social precarity of many families who do not use the standard health care structure. They must understand the reasoning behind the choices of these families, and be involved in the care of their children in places that they accept to visit. Paediatricians should also be present in institutions, conferences and debates where public health policy is discussed in order to defend the place of paediatrics in the sanitary organisation.     

The physical map of the chloroplast DNA from Korean ginseng (Panax ginseng C.A. Meyer)

To compare the gene order of the chloroplast genome among dicotyledonous plants, we constructed a physical map of chloroplast DNA (cpDNA) of Korean ginseng (Panax ginseng C.A. Meyer) with four restriction enzymes, BamHI, HindIII, EcoRI, and PstI. The restriction enzyme recognition sites of the physical map were also confirmed by Southern hybridization of total ginseng cpDNA with homologous and heterologous probes. The cpDNA of Korean ginseng was determined as a circular molecule with a total size of about 154 kb, which contain two inverted repeats of 23 kb each that disrupt the rest of the molecule into a large (90 kb) and a small single copy region (18 kb). The genome structure of Korean ginseng cpDNA was similar in size and gene order to that of tobacco cpDNA. The cpDNA of Korean and American ginseng (P. quinquefolius) showed very similar restriction patterns.