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Surface photovoltage spectroscopy (SPS) has been employed to monitor optical transitions in quantum well and superlattice structures at room temperature. Excellent agreement is found between theoretical predictions of heavy hole and electron energy level positions and the observed transitions. The results show that using this technique, the complete band diagram of the quantum structure may be constructed. SPS emerges as a powerful tool capable of monitoring optical transitions above the lowest one in a simple to interpret, contactless, and nondestructive way. more...

Computer simulations for the technique of estimating minimum alveolar anesthetic concentration (MAC) in patients (quantal design) suggest that incremental concentration changes and the number of crossovers affect MAC. We hypothesized that these variables may also apply to estimating MAC in rats (bracketing design). This study tested that hypothesis and also examined whether these variables might mask differences in MAC between groups in which MAC might be expected to differ (pregnant [P] versus nonpregnant [NP]). There were 2 cohorts (n = 27 and n = 30 rats). Each cohort included NP females, females in early P, and females in late P. MAC was tested by using an incremental concentration change of 0.20% and one within-subject crossover in the first cohort and by using an increment size of 0.10% and four crossovers in the second cohort. MAC was statistically significantly increased in the three groups in the second cohort (NP, 1.16 +/- 0.12; early P, 1.14 +/- 0.10; late P, 1.07 +/- 0.10; mean +/- sd) compared with values in the three comparable groups in the first cohort (NP, 0.95 +/- 0.06; early P, 1.01 +/- 0.09; late P, 0.93 +/- 0.13). Values did not differ among groups within each cohort. Post hoc simulations indicated that up to 36% of the difference between cohorts was due to increment size, with the balance due to experimental factors. Our findings confirmed the hypothesis that increment size affects estimates of MAC when a bracketing design is used. more...

Contact potential difference measurements in the dark and under illumination are used to derive the conduction band offset (ΔEc) in a solar cell quality junction formed by chemical bath deposition of CdS on a polycrystalline thin film of Cu(In,Ga)Se2. Our experimental measurements and the estimates made for dipole contributions show that the junction is of type II, i.e., without a spike in the conduction band ( ΔEc=80 meV±100 meV). This is consistent with the high performance of the actual solar cell. However, it differs from most previous results on junctions based on single crystals and/or vacuum deposited CdS, which indicated the existence of a conduction band spike. more...

Surface photovoltage spectroscopy (SPS) is used to determine the position of the deep defect state levels in undoped hydrogenated amorphous silicon (a‐Si:H). The occupied and the empty levels, and their nature, are identified with a clear advantage over existing methods. The identification of the levels and the effect of light soaking on their concentration provides direct experimental confirmation of the main features predicted by thermal equilibrium models. The finding of other levels in a‐Si:H materials of larger disorder further supports the recently proposed potential fluctuations model. more...

A novel approach for constructing the band diagrams of semiconductor heterojunctions is discussed and illustrated. It is based on a simple measurement of band discontinuities, Debye length and the width of the space–charge region at the heterojunction interface. Monitoring the changes in the surface potential during heterojunction formation makes it possible to identify the contributions of the interface states and dipole. The approach is illustrated by the results of experiments performed on the InP/In2O3 heterojunction. more...

The most common sleep disorder in children is obstructive sleep apnea syndrome (OSAS). The majority of children with OSAS improve following tonsillectomy and adenoidectomy (T&A). T&A as an outpatient procedure in children is very common. Young age in considered risk factors for postoperative respiratory complications. The purpose of this study is to analyze our experience with postoperative T&A complications in patients younger than 2 years of age. A total of 39 T&A were performed in children younger than 2 years of age. OSAS diagnosis was confirmed by overnight polysomnography (PSG). All the patients were hospitalized and monitored by overnight pulse oximetry monitoring. Post-operatively there was marked improvement in respiratory function in all the patients comparing pre- and post-operative nadir oxygen saturation (P more...

Impact ionization is generally taken as a phenomenon, responsible for breakdown in Pseudomorphic High Electron Mobility Transistor (PHEMT). Tuning and modeling the impact ionization phenomenon in PHEMT as a function of device design parameters can serve an effective optimization vehicle for the device manufacturer. The aims of this work are: a) developing a methodology for measuring and modeling impact ionization phenomena in PHEMT, b) developing an empirical model relating the device design parameters to impact ionization, using the methodology above. more...

Objective: Bradykinin (B) contributes to secondary brain injury. This injury is mediated in part by prostaglandin (PG). Antagonism of B 2 receptors improves neurological status after brain injury, but the effect of B 2 antagonism on brain tissue PG is unknown. This study examined the effect of LF 16-0687 Ms, a new B 2 receptor antagonist, on brain tissue PGE 2 after closed head trauma (CHT). Methods: Rats were anesthetized and received sham+saline, sham+LF 16-0687 Ms, CHT+saline, or CHT+LF 16-0687 Ms. Brain tissue samples were obtained at 24 h for determination of PGE 2 (after 2 h of ex vivo incubation) and water content. Neurological severity score (NSS) was assessed at 1 and 24 h. Results: In the group receiving CHT+LF 16-0687 Ms, brain tissue PGE 2 (77.7±65.9 pg/mg tissue, mean±SD) was less than in the group receiving CHT+saline (368.1±186.2 pg/mg tissue) and not different than sham+saline (78.7±30.7 pg/mg tissue). LF 16-0687 Ms also improved NSS and decreased brain water content by 51%. Conclusion: We conclude that the beneficial effect of LF 16-0687 Ms on outcome after CHT is accompanied by blockade of PGE 2 increase in injured brain tissue. more...

The conductance of transparent conducting oxide films as a function of their coverage has been investigated in situ. The films have been prepared by means of reactive evaporation of In in the presence of oxygen on the glass substrate at different substrate temperatures. The analysis shows that island growth, percolation, coalescence, and ohmic stages can be identified. Critical parameters of the films can be determined during the growth, such as anisotropic and percolative growth modes, resistivity, a lower limit of the effective dopant concentration. The technique shows a potential for in‐depth characterization of very thin film growth. more...

Samples of p-InP (100) have been investigated using temperature-controlled surface photovoltage spectroscopy (T-SPS), in conjunction with time-resolved photoluminescence and intensity-resolved surface photovoltage measurements. In addition to the previously reported three gap states, attributed to excess surface P, adsorbed O, and Fe unintentional doping, T-SPS reveals a gap state, also attributed to Fe, situated 0.79 eV below the conduction-band minimum. The energy distribution of the latter state has been investigated by measuring its population as a function of temperature and shows good agreement with theory. A direct observation of the spectral blueshift of the InP band gap by T-SPS shows very good agreement with theory. more...

A new experimental technique, which utilizes a tunable laser as the illumination source for surface photovoltage spectroscopy measurements, is presented. The data obtained by this technique make it possible to determine the distribution function of gap states observed at semiconductor interfaces. An outline of the approach together with experimental results obtained using a Ti:sapphire laser on InAlAs and CdTe crystals is given. more...

Spectroscopy of photoinduced changes in semiconductor Hall voltage is proposed as a method to characterize deep levels. An analytical expression for the Hall coefficient as a function of the charge trapped at grain boundaries is derived. The experimental Hall voltage is demonstrated by measuring thin films of GaN grown on sapphire and is shown to be consistent with the model. The Hall voltage spectrum is correlated to spectra from three other deep-level spectroscopies: photoluminescence, photoconductivity, and surface photovoltage, obtained under the same conditions from the same sample. Comparing spectra from the various spectroscopies shows that the yellow-luminescence-related deep states in GaN are charged in equilibrium and discharged by the exciting photons, and suggests that the blue-luminescence-related states are deep donors positioned 2.8 eV above the valence band and neutral in equilibrium. more...

The electronic structure and photoinduced surface/interface charge transfer processes have been studied in $\mathrm{poly}[2\ensuremath{-}\mathrm{methoxy}{\ensuremath{-}5\ensuremath{-}(2}^{\ensuremath{'}}\ensuremath{-}\mathrm{e}\mathrm{t}\mathrm{h}\mathrm{y}\mathrm{l}\ensuremath{-}\mathrm{h}\mathrm{e}\mathrm{x}\mathrm{y}\mathrm{l}\mathrm{o}\mathrm{x}\mathrm{y})\ensuremath{-}1,4\ensuremath{-}\mathrm{phenylene}\mathrm{}\mathrm{vinylene}]$ (MEH-PPV) thin films spin-coated on Au and n-GaAs(111) substrates using surface photovoltage spectroscopy. The results show that the MEH-PPV film is a p-type semiconductor with an optical band gap of around 2.1 eV and a surface work function of 4.7 eV, and its photovoltaic response is dominated by its free surface rather than the interface with the substrate. In addition, an acceptor surface state at 0.5 eV above the valence-band edge is found in films produced at low spinning rate, perhaps due to surface roughness. Efficient photoinduced electron injection from MEH-PPV films into the GaAs substrates is observed and found to have a strong dependence on the solvent used in the MEH-PPV spin deposition. These findings are discussed in view of the electronic and physical structure of the films. more...

A recently reported decrease of the reverse current in β‐FeSi2‐n‐type Si diodes under sub‐band‐gap illumination is theoretically considered. It is shown that this effect can be explained through a reduction of the generation component of the reverse current, which is caused by a decrease in the width of the space charge region due to illumination‐induced charging of deep impurities. Physical modeling of the effect is also presented. more...

Abstract —Mitogen-activated protein kinases (MAPKs) have been shown to be activated in both in vitro and in vivo models of cardiac tissue in response to ischemia/reperfusion injury. We investigated whether MAPKs are activated in human heart during coronary artery bypass grafting (CABG) surgery. During elective CABG surgery of 8 patients, 3 right atrial appendage biopsies were obtained at baseline, at the end of cross-clamping, and after coronary reperfusion. The expression of the p38-MAPK, c-Jun N-terminal kinase (JNK), and extracellular signal–regulated kinases (ERK1/2) MAPKs was not altered during CABG. The phosphorylation and activation of both ERK1/2 and p38-MAPK were increased ≈2-fold by ischemia and even more (8- and 4-fold, respectively) by reperfusion. Although the ischemic period did not result in a significant activation of JNK, an ≈6-fold increase in JNK activity could be observed after reperfusion. In conclusion, distinct activation patterns of ERK1/2, p38, and JNK MAPKs can be observed in human heart during CABG. more...

Summary: Recently, the enzyme cyclooxygenase (COX) has been recognized to exist as constitutive (COX-1) and inducible isoforms (COX-2). In previous studies, drugs that were inhibitors of both COX-1 and COX-2 failed to decrease brain edema formation or improve Neurological Severity Score (NSS) after closed head trauma (CHT), although some did decrease prostaglandin-E2 (PGE2) formation. The present study examined whether or not a specific inhibitor of COX-2 (nimesulide) exerts a beneficial effect after CHT in rats. Halothane-anesthetized rats (n = 8 in each group) were randomly assigned to one of four groups: surgery, no CHT, no drug (group 1); surgery, no CHT, nimesulide 30 mg/kg intraperitoneally (IP) (group 2); surgery, CHT, no drug (group 3); and surgery, CHT, nimesulide 30 mg/kg IP (group 4). NSS was determined at 1 and 24 h, and brain tissue PGE2 concentration and water content were determined after killing at 24 h. Treatment with nimesulide did not improve NSS (NSS at 24 h = 11 ± 6 [median ± range] in group 3 and 12 ± 4 in group 4) or edema formation (brain water content at 24 h = 84.3 ± 1.8% [mean ± SD] in group 3 and 83.8 ± 1.9% in group 4). However, nimesulide did decrease cortical and hypothalamic PGE2 formation by 41% and 47%, respectively during the first hour of incubation after brain tissue sampling. The authors conclude that although nimesulide does reduce tissue PGE2 formation, it does not exert a beneficial effect on brain tissue edema or functional activity after CHT in rats. more...

Diffusion-, perfusion-, T1-, and T2-weighted magnetic resonance imaging (MRI) were performed at 1–2 h, 24 h, and 1 week following closed head injury (CHI) in rats, and data was compared with hematoxylin and eosin histology. At 1–2 h, large areas of low perfusion in the damaged hemisphere overestimate the histological damage. In the first 2 h, the histological damage seems to be a superposition of abnormalities in the T1- and diffusion-weighted images. In areas with more than 10% reduction in the apparent diffusion coefficients (ADCs), reduced regional cerebral blood volume (r-CBV) was also observed. The decrease in ADCs and rCBV correlated with r = 0.78. Changes in the MRI parameters revealed the following: (a) Further reduction in ADC occurred from 83 ± 15% at 1–2 h after trauma to 69 ± 9% at 24 h, and 1 week later a marked elevation in the ADC values is observed. (b) Blood perfusion measurements performed 1–2 h posttrauma revealed a pronounced reduction in r-CBV (53 ± 18%) in the damaged hemisphere in all rats. At 24 h postimpact, areas of hyper- and hypoperfusion were observed. One week later, similar perfusion was found in both hemispheres of all rats. (c) T2 hyperintensity at 24 h overestimated the histological damage found at 1 week. At one week following the trauma, the T2 hyperintensity underestimated the histological damage. It is concluded that CHI, which is a heterogeneous insult, should be studied by a combination of MRI techniques. The superposition of the abnormalities seen on T1 and on the diffusion-weighted MR images at early time point represents best the histological damage. Both T2 and rCBV images are less informative in terms of actual histological damage. more...

Optically pumped stimulated emission is reported for the first time from Hg1−xZnxTe (x≊0.23) epilayers grown by liquid phase epitaxy. Pulsed lasing was observed up to 70 K. Maximum single mirror peak power output of 23 and 2 mW was measured at 12 and 70 K, respectively. The laser emission spectra consisted of a strong line around 5.4 μm, and a weaker one, 6–7 meV below it, which were attributed to band‐to‐band and to band‐to‐acceptor transitions. Far‐field patterns with angular width of θ⊥=4° and θ∥≊2.5° have been observed perpendicular and parallel to the layer plane, respectively. more...

The present study examined whether hemodilution with 20% human serum albumin (HSA) or 10% hydroxyethyl starch (HES) improved the outcome from closed-head trauma (CHT) in rats. Rats anesthetized with halothane were given one of three hemodilution solutions (i.e., 20% HSA, 10% HES, or control [0.9% saline]) after CHT or sham surgery. CHT was delivered using a weight drop impact of 0.5 J onto the closed cranium. The hemodilution solution (volume = 1% of body weight) was given just after determining the neurological severity score (NSS) at 1 hour following CHT. The NSS was determined again at 24, 48, and 72 hours following CHT. At 72 hours, brains were removed, and brain edema and brain tissue necrosis volume were determined. Solutions of 20% HSA and 10% HES significantly improved brain tissue necrosis volume (143 +/- 72 mm3 and 104 +/- 53 mm3 as compared to 271 +/- 65 mm3 in controls, mean +/- SD) and NSS (12 +/- 2 and 9 +/- 2 as compared to 15 +/- 2 in controls at 72 hours, median +/- range) but not brain edema. The hematocrit decreased similarly in all groups during hemodilution. Hemodilution with 20% HSA and 10% HES following CHT in rats did not decrease brain edema but did decrease brain tissue necrosis volume and NSS (improved neurological function), suggesting that the beneficial effect of hemodilution resulted not from decreased edema formation but rather from effects not measured in this study such as improved perfusion of the salvageable brain tissue surrounding the core injury. more...

Direct measurements of the surface recombination velocity (SRV) on etched InP(110) and at its interfaces with various metals deposited by thermal evaporation have been performed using ultrafast time‐resolved photoluminescence. The results show that the original InP low SRV is retained when these surfaces are coverd with metals which tend to react with the semiconductor’s anion, such as Al, Cr, and Zn. On the other hand, the SRV increases sharply as a function of unreactive metal coverage, such as Cu, Au, and Ag. The SRV results are explained in terms of metal‐induced interface states, whose position in the band gap and thus their cross section for recombination depends on the metal reactivity. The similarity of the SRV and the reported Schottky barrier height dependence on the metal‐phosphorus heat of reaction is noted. more...

Surface photovoltage spectroscopy has been used in order to investigate surface states at Al/n‐GaAs (110), Au/n‐GaAs (110) and Al/p‐InP (110), Au/p‐InP (110),(100) interfaces. Our results show formation of metal‐induced surface states, which can be correlated with Fermi level pinning positions. The observed energy positions are found to be in good agreement with electrically measured Schottky barrier heights. The results obtained for these metals and the different surface types are discussed and compared to published data. more...

Diodes with transparent top contacts were fabricated by depositing indium oxide layers onto n‐type GaAs by means of reactive evaporation of In in the presence of oxygen. The electrical characteristics as well as the structural properties and chemical composition of the resulting junctions were studied using Auger electron spectroscopy, x‐ray diffraction, optical absorption, capacitance‐voltage, and dark current‐voltage measurements. The best diodes were obtained under deposition conditions of substrate temperature 250 °C and oxygen pressure 5×10−4 mbar; these diodes exhibited a Schottky barrier height of 0.85 V with an ideality factor of 1.04. The indium oxide films were found to be polycrystalline and to have an electrical resistivity of 3×10−4 Ω cm and an optical transmittance above 90% over the whole visible range. The effect of deviations from the optimal deposition parameters on the diode properties is discussed. more...

Direct measurements of the surface recombination velocity (SRV) on etched CdS(1120), CdSe(1120) and at their interfaces with various metal ions and metals (deposited by electrolyte aqueous solutions and in situ thermal evaporation, respectively) have been performed using ultrafast time‐resolved photoluminescence (PL). Correlations with interface states types and energy positions have been found based on surface photovoltage spectroscopy (SPS). The results show that the original semiconductor SRV is retained, and in some cases even decreases, when these surfaces are covered with metals, which tend to react with the semiconductor’s anion, such as Al, Ti, and Zn. On the other hand, the SRV increases sharply as a function of unreactive metals coverage, such as Cu, Au, etc. The PL results are explained in terms of metal‐induced recombination centers at the semiconductor interface, which are introduced or eliminated as observed by SPS. more...

Direct measurement of the surface recombination velocity (SRV) on etched CdS (11 2 0) and at its interface with several metals (deposited by aqueous solutions and in situ thermal evaporation) was achieved by using ultra-fast time-resolved photoluminescence (PL). The results show that Ag deposition increases the original SRV by about three orders of magnitude while Zn virtually does not change it. The results are discussed in view of the pronounced effects on SRV of reactive and unreactive metals and of the deposition method. more...

In a model of uncontrolled hemorrhagic hypotension (UCHH) in rats, we examined whether blood loss or blood chemistry were affected by (1) deliberate, controlled hypotension induced with labetalol (L) or sodium nitroprusside (SNP) and (2) intravenous (iv) fluid therapy. Two hours of UCHH was induced by resecting the distal 25% of the tail. L or SNP was infused with the aim of decreasing MAP to 50 mmHg. In the groups receiving iv fluid, 3 ml of 0.9% saline was given for each 1 ml of blood loss. L decreased blood loss (2.8+/-2.0 and 3.0+/-1.9 ml, respectively, in the groups not receiving and receiving iv fluid) compared to the groups not given hypotensive drugs (6.3+/-4.1 and 13.5+/-6.6 ml). SNP did not decrease blood loss (5.7+/-4.7 and 11.0+/-6.2 ml), increased serum potassium (5.0+/-0.6 and 5.8+/-0.4 mEq l(-1)), and with accompanying iv fluid administration decreased hematocrit, worsened acidosis, and increased mortality. In this model of 2 h of UCHH in rats, hypotension to MAP of 50 mmHg with L but not with SNP decreased blood loss. more...

Closed head trauma (CHT) increases brain tissue prostaglandin E2 (PGE2) concentration, and that increase is associated with cerebral edema formation and worsening of the neurologic severity score (NSS). Injection of the bacterial endotoxin lipopolysacharride (LPS) increases cerebral and hypothalamic PGE2, and the hypothalamic increase is associated with increased body temperature. The present study determined (a) whether LPS-induced increase of PGE2 causes brain edema or worsens NSS and (b) whether CHT increases hypothalamic PGE2 and thereby increases body temperature. Halothane-anesthetized rats were divided into four groups: group 1 = surgery with no CHT and no LPS (n = 8); group 2 = surgery with LPS and no CHT (n = 8); group 3 = surgery with CHT and no LPS (n = 8); and group 4 = surgery with CHT plus LPS (n = 8). NSS was determined at 1 and 24 h after injury, and brain tissue PGE2 and edema were determined when animals were killed 24 h after injury. As compared with group 1, LPS alone, but not CHT or CHT plus LPS, increased rectal temperature. CHT and CHT plus LPS, but not LPS alone increased brain water content and worsened NSS. LPS, CHT, and CHT plus LPS all increased hypothalamic and cerebral PGE2 production. We conclude that although LPS and CHT increased PGE2 levels, LPS alone did not affect neurologic status or brain edema, CHT did not increase rectal temperature, and addition of LPS to CHT did not aggravate the sequelae of CHT. more...

A possibility to produce a Schottky barrier at the Ag/C60 thin film interface has been demonstrated. The device structure exhibited rectifying behavior in the dark and photovoltaic properties.

Contact potential difference measurements in the dark and under illumination are used to derive the conduction band offset (ΔEC) in the CdS/Cu(In,Ga)Se2 junction before and after air annealing. This junction was formed by chemical bath deposition of CdS on state‐of‐the‐art, solar cell quality, polycrystalline thin films of Cu(In,Ga)Se2. Based on our experimental measurements and estimates made for dipole contributions, we find that the junction in the cell is of type II, i.e. without a spike in the conduction band (ΔEC=80 meV±100 meV). Air annealing improves cell performance and also markedly increases the surface photovoltage spectral response. However, the annealing treatment is shown to have no significant effect on the band line‐up of the heterojunction, which remains type II. This indicates that air annealing of these junctions does not change the built‐in voltage or the band line‐up. more...

Electron transfer from sol–gel–prepared TiO2 into adsorbed benzene diazonium compounds has been investigated using cyclic voltammetry, x-ray photoelectron spectroscopy, contact potential difference, and surface photovoltage spectroscopy. The results show that the potential of maximum electron transfer depends strongly on the dipole moment of the benzene compound. Two reactive surface sites at which electron transfer occurs have been identified. more...

The purpose of the present study is to investigate whether hemodialysis (HD) is effective in lowering blood glutamate levels. In addition, we examined the effect of HD on glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) levels in the blood and described the rate and pattern of blood glutamate clearance during HD.Blood samples were taken from 45 patients with stage V chronic kidney disease immediately after initiation of HD and hourly, for a total of 5 blood samples. Samples were sent for determination of glutamate, glucose, GOT, GPT, hemoglobin, hematocrit, urea, and creatinine levels. A blood sample from 25 healthy volunteers without chronic renal failure was used as a control for the determination of baseline blood levels of glutamate, GOT, and GPT.Glutamate and GPT levels in patients on HD were higher at baseline compared with healthy controls (P.001). In the first 3 hours after HD, there was a decrease in blood glutamate levels compared with baseline levels (P.00001). At the fourth hour, there was an increase in blood glutamate levels compared with the third hour (P.05).Hemodialysis may be a promising method of reducing blood glutamate levels. more...

The formation of thin overlayers of In on Si(111)7×7 substrate surfaces has been studied in the temperature range from room temperature to ∼500 o C by Auger-electron spectroscopy, low-energy electron diffraction, direct and inverse photoemission spectroscopy (UPS and IPES), and electron-energy-loss spectroscopy (EELS). Up to In coverages Θ ln of about 1-2 monolayers (ML), uniform layer growth prevails irrespective of the substrate temperature, but ordered surface structures can only be observed at elevated temperatures. Beyond Θ ln =1-2 ML, three-dimensional island clustering according to the Stranski-Krastanov mechanism appears, but the growth rate appears to be greatly reduced for substrate temperatures >300 o C more...

We previously described the time course of changes in neurologic status (as indicated by neurologic severity score [NSS]) and cerebral edema (as indicated by brain tissue specific gravity and water content) after closed head trauma in rats. The present study was designed to determine whether head trauma alters the integrity of the blood-brain barrier (BBB), the role of the BBB in edema formation and neurologic outcome, and the effect of MK-801 (a noncompetitive N-methyl-D-aspartate receptor antagonist) on BBB permeability. Rats in which cranial impact was delivered during ether anesthesia (n = 106) were killed at 15 min, 1, 2, 4, 10, and 24 h, and 2, 4, and 7 days. Control rats (n = 12) received no cranial impact. Subsets of head-injured rats killed at 4 and 24 h received MK-801 (3 mg/kg intraperitoneally) 1 h after injury. BBB permeability was assessed with intravenous injection of Evans Blue dye, cerebral edema was assessed by determining brain tissue specific gravity and water content, and neurologic status was assessed using NSS. Tissue extravasation of Evans Blue was maximal in the injured hemisphere 4 h after injury, but a residual BBB permeability defect was still evident as long as 4 days after the insult. In MK-801-treated rats, extravasation of Evans Blue in the injured hemisphere was not significantly different from that in the noninjured hemisphere.(ABSTRACT TRUNCATED AT 250 WORDS) more...

SiC metal oxide semiconductor field effect transistors grown on low-doped epilayer channels and on ion-implanted channels with either “as grown” or NO annealed thermal oxides have been electrically characterized. The threshold voltage, effective electron mobility, as well as fixed charge, oxide trap, and interface trap concentrations have been separately obtained using conventional dc sweep, capacitance-voltage (C-V), fast current-voltage (I-V), and low frequency noise measurements. The results show that devices with as grown SiO2 have a much higher density of “slow” bulk oxide traps than devices after postoxidation annealing in NO. The oxide fixed charge density is unaffected by the annealing process. Devices fabricated on ion-implanted channels exhibit only a small increase in the slow bulk oxide trap density and the fixed charge. However, the density of the “fast” interface traps increases dramatically. This suggests that the damage due to the ion-implantation process is mainly interfacial. In contrast... more...

Direct measurements of the intrinsic surface-recombination velocity (SRV) on p-type InP have been performed using ultrafast time-resolved photoluminescence. The results show that the intrinsic SRV on p-type InP is low (\ensuremath{\sim}500 cm/s), similar to the value reported for n-type InP surfaces. It is suggested that the low luminescence efficiency of p-type InP is due to its low effective bulk lifetime (23 ns) and to a large surface band bending, and does not indicate high SRV as has been generally accepted. more...

WOMEN HANNY PAL OHANA, AMALIA LEVY, AMIT ROZEN, YORAM SHAPIRA, LEV GREEMBERG, EYAL SHEINER, Soroka University Medical Center, Ben-Gurion University of the Negev, Department of Obstetrics and Gynecology, Beer-Sheva, Israel, Ben Gurion University of the Negev, Faculty of Health Services, Epidemiology, Beer-Sheva, Israel, Soroka University Medical Center, Ben-Gurion University of the Negev, Division of Anesthesiology, Beer-Sheva, Israel OBJECTIVE: The present study was designed to investigate the influence of epidural analgesia on mode of delivery in nulliparous women. STUDY DESIGN: A population-based study comparing women with and without epidural analgesia was conducted. A multivariable logistic regression model with backward elimination was constructed to control for confounders. RESULTS: During the study period there were 39,498 deliveries, and in 9,960 (25.2%) of these, epidural analgesia was introduced. Using a multivariable analysis with backward elimination, the following conditions were significantly associated with the use of epidural analgesia: advanced maternal age (OR 1.1; 95% CI 1.041.05; P 0.001), oligohydramnios (OR 1.2; 95% CI 1.1-1.4; P 0.004), PROM (OR 1.5; 95% CI 1.4-1.6; P 0.001), and induction of labor (OR 2.2; 95% CI 2.1-2.4; P 0.001). These patients were more likely to deliver by cesarean delivery (CD; 11.4% vs. 8.7%, P 0.001) and vacuum extraction (9.0% vs. 6.1%, P 0.001). However, after controlling for possible confounders such as failed induction, maternal age, etc, epidural analgesia was not found to be an independent risk factor for CD but rather a protective factor (P 0.038, Table). On the contrary, when vacuum extraction was the outcome variable, epidural analgesia was documented as an independent risk factor (P 0.04, Table). CONCLUSION: Epidural analgesia in nulliparous parturients is an independent risk factor for vacuum extraction. Nevertheless, it does not pose an independent risk for cesarean delivery. more...

Charge separation processes were studied at tetraphenyl-porphyrin (H2TPP)/metal oxide interfaces by surface photovoltage spectroscopy. The thickness of the depleted Ti and Sn oxide layers was about 2nm. Acceptorlike interface states play a crucial role in the steady-state light-induced negative charging of H2TPP surface layers as well as in tunneling or light-induced discharging. The results indicate that steady-state negative charging of the H2TPP layer is induced by preferential recombination of holes at the (H2TPP)/metal oxide interface and depends only weakly on temperature. The modulated surface photovoltage is dominated by hole transport at low temperatures and by electron transport at higher temperatures. The activation energy of the latter is of the order of 0.4eV. more...

A frequency and temperature dependent change of the sign of modulated surface photovoltage signals from metal-free tetraphenyl porphyrin (H2TPP)∕Au junctions has been observed. The sign of the modulated photovoltage signal could be switched by using continuous (bias) illumination, while the sign depends on the wavelength of the bias light. The light induced modulation of the negative and positive charges in the H2TTP layer can be interpreted in terms of internal photoemission of electrons from Au into H2TTP and of hole escape after exciton dissociation at the H2TPP∕Au junction. more...

We present a summary of a comprehensive study of transport, phototransport, surface photovoltage spectroscopy and luminescence of self-standing films of mesoporous and nanoporous silicon. We conclude that the visible luminescence arises from optical bandtail transitions in the silicon crystallites, while the transport is via a disordered silicon shell that wraps the crystallites. more...