P type conductivity

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Increased p type conductivity in GaNxSb1−x, experimental and theoretical aspects

Increased p type conductivity in GaNxSb1−x, experimental and theoretical aspects

line-shape S parameter and corresponding drop in the inten- sity at low momenta was measured with increasing N content for both epitaxial layers grown on GaAs and on GaSb. From the measured positron data, we conclude that similar types of positron trapping defects exist in both sets of samples; there- fore, lattice mismatches do not play a significant role in nei- ther the positron trapping nor in the increased p-type conductivity. Traditionally, a decrease in the S parameter has been interpreted as a reduction in the fraction of positrons trapping into open-volume defects. However, a change in the charge state of the defect can lead to a somewhat different S parameter since the atoms neighboring negative vacancies can relax inwards. 54 For the layers with N, the measured large increase in the p-type conductivity indicates an increase in negatively charged defects in the material. In addition to the increase in charged defects, the calculations indicate that the added nitrogen can also affect the shape of the annihilation line in the case of positrons localizing at or near to nitrogen atoms. Therefore, the conventional interpre- tation of the line-shape parameters might in this case not be suitable for the studied material.
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Acceptor formation in Mg doped, indium rich Gax
              In1−xN: evidence for p type conductivity

Acceptor formation in Mg doped, indium rich Gax In1−xN: evidence for p type conductivity

The temperature dependence of the Hall density and mobility for the Mg-doped material (GS1989) is shown in Figure 2c,d. Electron mobility decreases with increas- ing temperature from 0.16 m 2 V −1 s −1 at T = 2 K to 0.003 m 2 V −1 s −1 at T = 300 K, while the carrier density changes considerably more than that in the undoped material from around 2 × 10 11 to 9.0 × 10 13 m −2 in the same temperature range. We have plotted the logarithm of the Hall carrier density as a function of inverse temperature in Figure 3. There is a clear tendency to an activated behaviour at high temperatures. This observa- tion may be explained speculatively, in terms of a mech- anism involving two-channel conductivity with both types of type carriers, namely: (1) the 2DEG accumula- tion at the surface layer where the density for these car- riers will be temperature independent as it is the case in undoped material as shown in Figure 2a and (2) the bulk layer. For the bulk conductivity, we may assume either of the equally plausible three scenarios: (1) The whole bulk layer is p-type or (2) p-type conductivity occurs in the bulk layer only below a certain depth from the sur- face and adjacent to the bottom buffer layer as suggested by Jones et al. and Ager et al. [20,29]. Alternatively, (3) p-type conductivity is not within a uniform layer but occurs through p-type percolation channels around slightly compensated n-type islands, the sizes of which may vary, depending on the local electron and hole densities, from nano to microscale islands or chain (similar to the model that was proposed by us and Ridley [30]) to explain successfully hot electron percolation in 2-D GaAs and superconductivity in InN [31]. These three mechanisms are depicted schematically in Figure 4. In either of the three models, at high temperatures as
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Origin of the n type and p type conductivity of MoS2 monolayers on a SiO2 substrate

Origin of the n type and p type conductivity of MoS2 monolayers on a SiO2 substrate

A trap state is usually formed when an energy level associated either to a defect or an impurity appears within the energy gap of the host material. Such trap states influence the charge transport properties mainly in two ways. First, if the traps are charged, they will capture a hole or an electron from the environment. This produces a modification of the electrostatic potential, which in turn shifts the level alignments in the system, and thus affects the conductivity. Second, they can also increase the carrier concentration and provide pathways for electrons or holes to hop. The efficiency of this process depends on the amount of localization of the states associated to the defect site. If the energy of the localized gap state is close to either the valence band maximum (VBM) or the conduction band minimum (CBM), then at a given temperature some of these charges will be transferred either to the conduction or to the valence band, where they may contribute to increase the system conductivity.
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Change in Surface Conductivity of Elastically Deformed p Si Crystals Irradiated by X Rays

Change in Surface Conductivity of Elastically Deformed p Si Crystals Irradiated by X Rays

Silicon mono-crystals of p-type conductivity, grown by Czochralski method ( ρ = 10 – 20 Ω cm), were used in the research paper. These mono-crystals are of two types: (1) silicon for electronics—the so-called dislocation-free (or electronic) mono-crystals on the surface (111) of which, the concentration of triangular etch pits does not exceed 10 2 cm − 2 (Figs. 1a and 2), and (2) “ solar ” mono-crystals of silicon on the surface (111) of which, the defects in the form of 4-angular pyramids (Fig. 1b) were discovered due to a relatively large concentration of the background carbon ( ≈ 5 × 10 16 cm − 3 ) and oxygen ( ≈ 1.8 × 10 18 cm − 3 ) impurities.
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EFFECT OF ELEVATED TEMPERATURE ON COMPRESSIVE STRENGTH OF CONCRETE

EFFECT OF ELEVATED TEMPERATURE ON COMPRESSIVE STRENGTH OF CONCRETE

The present work focuses on study of compressive strength of concrete subjected to elevated temperatures, effect of cooling regime on strength of normal concrete at elevated temperatures. In this project the compressive strength of normal M-20 grade concrete in addition to polypropylene fiber at temperature 30°C, 100°C, 300°C, 500°C, 600°C,7 00°C and 800°C is tested with the different type of cooling air and water quenching.

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I. The attenuation and dispersion of sound in a condensing medium. II. The flow of a gas-particle mixture downstream of a normal shock in a nozzle

I. The attenuation and dispersion of sound in a condensing medium. II. The flow of a gas-particle mixture downstream of a normal shock in a nozzle

36 h enthalpy of gas, per unit mass latent heat of vaporization complex wave number thermal conductivity of gas k-l thermal conductivity of liquid K eT v p equilibrium vapor mass fracti[r]

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<p>Role of pseudohypoxia in the pathogenesis of type 2 diabetes</p>

<p>Role of pseudohypoxia in the pathogenesis of type 2 diabetes</p>

Abstract: Type 2 diabetes is caused by persistent high blood glucose, which is known as diabetic hyperglycemia. This hyperglycemic situation, when not controlled, can overproduce NADH and lower nicotinamide adenine dinucleotide (NAD), thereby creating NADH/NAD redox imbalance and leading to cellular pseudohypoxia. In this review, we discussed two major enzymatic systems that are activated by diabetic hyperglycemia and are involved in creation of this pseudohypoxic condition. One system is aldose reductase in the polyol pathway, and the other is poly (ADP ribose) polymerase. While aldose reductase drives overproduction of NADH, PARP could in contrast deplete NAD. Therefore, activation of the two pathways underlies the major mechanisms of NADH/NAD redox imbalance and diabetic pseudohypoxia. Consequently, reductive stress occurs, followed by oxidative stress and eventual cell death and tissue dysfunc- tion. Additionally, fructose formed in the polyol pathway can also cause metabolic syndrome such as hypertension and nonalcoholic fatty liver disease. Moreover, pseudohypoxia can also lower sirtuin protein contents and induce protein acetylation which can impair protein function. Finally, we discussed the possibility of using nicotinamide riboside, an NAD precursor, as a promising therapeutic agent for restoring NADH/NAD redox balance and for preventing the occurrence of diabetic pseudohypoxia.
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Effect Of Partial Substitution Of Tb In La2Mo2O9 Oxide Ion Conductor

Effect Of Partial Substitution Of Tb In La2Mo2O9 Oxide Ion Conductor

0.5), in search of desired result. The sample were characterised via XRD, SEM, DSC and EISSA to study the structural, phase transition and the ionic conductivity of the synthesised sample. The experimental as well as result obtained are discussed in the following sections.

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Thermal Transmission Attributes of Knitted Structures Produced by Using Engineered Yarns

Thermal Transmission Attributes of Knitted Structures Produced by Using Engineered Yarns

• “Type A” yarn keeps wearers comfortable, dry and odour-free. Unlike other topically finished performance polyesters that lose their ability to wick away moisture with each washing, the comfort qualities of this fabric are permanent. “Type A” yarn has a patented blend of natural and synthetic fibers. The natural fibers absorb moisture by pulling it from the skin and into the fabric. The synthetic fibers repel moisture, forcing it through to the surface of the garment where it evaporates quickly as airflow moves across the fabric.

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Effect of slaughter season on postmortem metabolic characteristics of muscle in the dromedary camel (Camelus dromedarius)

Effect of slaughter season on postmortem metabolic characteristics of muscle in the dromedary camel (Camelus dromedarius)

stores (Kadim et al., 2006; Abdelhadi et al., 2015). The pHu value of meat is determined by a combination of many factors, including preslaughter handling, postmortem treatment and muscle physiology (Thompson, 2002). This study found no significant effect of slaughter season on electrical conductivity measured at 90 min. However, the effect of different slaughter seasons on electrical conductivity at 48 h was significant, with this variable being lower in winter than in summer. This increase in electrical conductivity during the summer may have been due to high ambient temperature having a stimulatory effect on enzyme activity during postmortem glycolysis.
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<p>Khat Chewing and Type 2 Diabetes Mellitus</p>

<p>Khat Chewing and Type 2 Diabetes Mellitus</p>

Data entry and analysis were performed using Statistical Package for the Social Sciences software version 24. 27 The data were coded with anonymous identi fi cation numbers in order to guarantee the privacy of the participants. The continuous variables were described by means and stan- dard deviation (SD) and the categorical variables by per- centages and frequencies. A chi-square test for independence was used to assess the associations among the categorical variables. Binary logistic regression was used to explore the predictors of T2DM including the signi fi cant variables in univariate regression. The assump- tions of the binary logistic regression were checked for the presence of outliers and multicollinearity (high inter- correlations among independent variables). In other way in the analysis, an independent t-test was also performed to test for any mean differences between the studied groups. P values <0.05 were considered to be statistically signi fi cant.
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Design and synthesis of nitric oxide releasing polymers for biomedical applications

Design and synthesis of nitric oxide releasing polymers for biomedical applications

Glutaric acid (GA), adipic acid (AA), pentaerythritol, cysteamine, penicillamine, and N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC) were purchased from the Aldrich Chemical Company (Milwaukee, WI). Glycerol, N- hydroxysuccinimide (NHS), and laboratory grade salts and solvents were purchased from Fisher Scientific (Fair Lawn, NJ). Sodium nitrite was purchased from Acros Organics (Morris Plains, NJ). Diethylenetriamine-pentaacetic acid (DTPA) was purchased from Fluka (Buchs, Switzerland). Tryptic soy broth (TSB) and Minimum Essential Media (MEM) was purchased from Becton, Dickinson, and Company (Sparks, MD). Nitric oxide calibration gas (25.85 ppm; balance nitrogen) was purchased from National Welders Supply Co. (Durham, NC). Pseudomonas aeruginosa (ATCC #19143) was obtained from American Type Culture Collection (Manassas, VA). Water was purified to 18.2 ΜΩ⋅cm using a Millipore Milli-Q Gradient A-10 purification system (Bedford, MA).
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Structural Basis for Metallic Like Conductivity in Microbial Nanowires

Structural Basis for Metallic Like Conductivity in Microbial Nanowires

In contrast, examination of the predicted positioning of the aromatic amino acids in the model of the P. aeruginosa pilus struc- ture (24) indicated that the distances between the majority of the aromatic amino acids were 10 to 40 Å (see Fig. S5 in the supple- mental material). This is consistent with the previous finding that the pili of P. aeruginosa are not conductive (7, 18). The pilin of P. aeruginosa contains 7 aromatics compared to 6 for G. sulfurre- ducens (Fig. 6). Positions 1, 24, and 27 in the ␣-helix are common for aromatics, whereas G. sulfurreducens pilin contains additional aromatics at positions 32, 51, and 57. P. aeruginosa contain addi- tional aromatics at positions 55, 102, 127, and 137. Thus, G. sul- furreducens pilin possesses 2 more aromatics in its ␣-helix, which are absent in the ␣ -helix of P. aeruginosa pilin. The absence of these aromatic amino acids in the P. aeruginosa ␣-helix might result in a gap among aromatics that prohibits charge transfer. Thus, the distribution of aromatics along the ␣-helix and the dis- tance between helices may be the decisive factor in the pilus con- ductivity. The G. sulfurreducens pilin is much smaller (61 amino acids) than the P. aeruginosa pilin (144 amino acids), which has a globular head domain that leads to a pilus that is thicker (5 to 6 nm in diameter) (24) than the G. sulfurreducens pilus. This almost 2-fold difference in the thickness suggests that the ␣-helices in the pilus of P. aeruginosa are much farther apart due to the presence of the globular domain. Thus, the aromatics in the ␣-helix will not be
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<p>Boston Type 1 Keratoprosthesis: Updated Perspectives</p>

<p>Boston Type 1 Keratoprosthesis: Updated Perspectives</p>

Abstract: The use of Boston type 1 keratoprosthesis (BKPro) has signi fi cantly increased worldwide. It is no longer considered a procedure of last resort but a reasonable option for patients with otherwise poor prognosis for a traditional penetrating keratoplasty. BKPro was approved by the Food and Drug Administration in 1992 for bilateral severe corneal blindness due to multiple corneal transplant failure. Over the years, indications have extended beyond recurrent immunologic rejection to include other conditions such as chemical injury and other causes of bilateral limbal stem cell de fi ciency, extensive corneal neovascularization, neurotrophic corneas and hypotony, among others. Numerous advances in the design of the BKPro, improvement of preoperative, intraoperative and postoperative management have resulted in favorable outcomes and a reduction in post- operative complications. Accordingly, many studies have shown that implantation of this device is highly effective in restoring vision with very good short-term outcomes. However, due to the lifetime risk of sight-threatening complications after BKPro implan- tation, a longer follow-up period should provide outcomes that are more realistic. In this review, the authors examined only the results of publications with an average of at least 2 years of follow-up. The overall intermediate to long-term visual outcomes and retention rate in BKPro seem to be favorable. However, autoimmune diseases and cicatrizing conditions continue to show a higher incidence of postoperative complications that require further management.
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Using AC Conductivity Measurements to Study the Influence of Mechanical Stress on the Strength of Geomaterials

Using AC Conductivity Measurements to Study the Influence of Mechanical Stress on the Strength of Geomaterials

Pilot ac conductivity measurements in the frequency range 1 kHz - 1 MHz were conducted for type-1 and type-2 specimens without removing their natural mois- ture. Figure 4 shows the behaviour of the ac conductivity with respect to the frequency for type-1 and type-2 speci- mens. It becomes clear that type 2 specimens exhibit higher ac conductivity in the whole frequency range. This behaviour can be attributed to the fact that the external electric field applied to measure the ac conductivity was directed in parallel to the muscovite and chlorite layers that act as conductive paths between the two electrodes of the dielectric measurements probe (see Figure 1).
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Role of Interatomic Potentials in Simulation of Thermal Transport in Carbon Nanotubes

Role of Interatomic Potentials in Simulation of Thermal Transport in Carbon Nanotubes

In the first part of this study, we calculate thermal conductivity of (5,5) nanotube against the temperature for 12 nm and 20 nm nanotube lengths. As temperature rises, two things happen. On the one hand, more phonons will be excited, which play a positive role in heat transport. On the other hand, umklapp scattering of phonons which leads to a decrease in the phonon mean free path increases. At low temperatures, umklapp scattering can not significantly disturb the positive effects of increased energy carriers. Hence, as expected from theoretical and experimental studies [12, 37], one can clearly see that thermal conductivity curve grows with increasing temperature for both types of used potentials. The obtained results show a power law behavior for thermal conductivity against the temperature.
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Soil factors determining the distribution of Phragmites australis and Phacelurus latifolius in upper tidal zone

Soil factors determining the distribution of Phragmites australis and Phacelurus latifolius in upper tidal zone

To assess the environmental factors determining the zonation between Phacelurus latifolius and Phragmites australis, vegetation survey and soil analysis were performed at a tidal marsh. The vegetation of the tidal marsh was classified into P. latifolius and Suaeda japonica dominated quadrats, P. latifolius and P. australis dominated quadrats, P. australis dominated quadrats, and P. australis and other land plants dominated quadrats. The density of P. latifolius (83.7 ± 5.5 shoots m − 2 ) was higher than that of P. australis (79.3 ± 12.1 shoots m − 2 ) in each dominated quadrat but height of two species were similar. Soil environmental characteristics of P. latifolius dominated quadrats appeared to be affected by tide based on higher soil electric conductivity (EC PL = 1530 ± 152 μ S cm −
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THE THIRD GENERATION DYE-SENSITIZED SOLAR CELL

THE THIRD GENERATION DYE-SENSITIZED SOLAR CELL

453 | P a g e TiO2 layer on a transparent conductive glass substrate, an iodide/ triiodide redox couple in an organic solvent as an electrolyte, and a platinum film having high electrocatalytic activity coated on conductive glass as counter electrode; its operation is similar to that of photosynthesis. The operation of DSSC can be explained in three steps: first the dye molecule absorbs the photon and gets excited. The excited dye molecule is then given off to the conduction band of semiconductor and it gets oxidized. After that the transparent conducting oxide (TCO) layer collects the excited electron from the conduction band and the electrons flow from the external load to the counter electrode. Finally the oxidized dye molecule is reduced by gaining electrons from the electrolyte solution (Fig 1). DSSC is the only device that absorbs photon and converts them to electric charge without the need of intermolecular transport of electronic excitation. In conventional solar cells both light absorption and charge carrier transport were performed simultaneously, whereas in DSSC the two operations are performed separately. An energy conversion efficiency of more than 11 per cent has been achieved in DSSCs with an organic liquid-based electrolyte containing I3-/I- as a redox couple.
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Influence of the Electrolyte Salt on the Electrochemical Polymerization of Pyrrole. Effects on p-Doping/Undoping, Conductivity and Morphology

Influence of the Electrolyte Salt on the Electrochemical Polymerization of Pyrrole. Effects on p-Doping/Undoping, Conductivity and Morphology

Comparison of the charges obtained for analogous deposits generated by the two different perturbations usually shows that deposits electrosynthesized by CV present higher charge, independent of whether the p-doping/undoping process be always reversible. That is, when comparing the p- doping/undoping charge values of electrosynthesized PPy using FP and CV, an important increase for the same salt in the supporting electrolyte stands out: deposits prepared by potentiodynamic perturbing exhibit between 15 and 60% more charge than those synthesized using potentiostatic perturbing.
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Effects of Mg 2+ interstitial ion on the properties of Mg 0 5+x/2 Si 2 x Al x (PO 4 ) 3 ceramic electrolytes

Effects of Mg 2+ interstitial ion on the properties of Mg 0 5+x/2 Si 2 x Al x (PO 4 ) 3 ceramic electrolytes

The plot can be divided into three regions; the low frequency, intermediate frequency and high frequency regions. The spectra exhibit a spike in low frequency region due to the polarization effects where the blocking of ions between the sample and electrode occurs. There is a plateau at the intermediate fre- quency region and extrapolating it to the y-axis gives the value of direct current conductivity, σ dc [17,18]. In this region, the

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