Saturated electric field effect at semi-insulating GaAs-metal junctions studied with a low energy positron beam

The interfacial electric field established under different reverse bias conditions in Au and Ni on semi-insulating GaAs junctions has been studied by means of a low energy positron beam. The technique used is that of monitoring the positron drift to the interface through changes in the annihilation radiation lineshape as a function of incident positron beam energy at different reverse biases The data show a small but clear electric field drift of positrons towards the interface that increases more rapidly at low voltages (less than 50 V) which at higher biases tends towards saturation This confirmation of electric field saturation adds further weight to the picture of an electric field enhanced electron capture cross section for the ionized EL2 defect. Electric field values extracted from the data are compared with results from other techniques and suggest that enhanced electron capture is already occurring at the relatively low built-in fields (∼1 kV cm-1) found at the unbiased junction, with a rapid increase of EL2+ neutralization occurring for biases above 10 V. At still higher fields ∼10 kV cm-1 (biases>50 V), there appears to be an additional threshold for more complete EL2+ neutralization adjacent to the contact. The present study clearly demonstrates the often overlooked necessity of catering for built-in electric fields in positron diffusivity studies of III-V semiconductors where surface midgap Fermi-level pinning is common. © 1997 American Institute of Physics.published_or_final_versio

Electric-field distribution in Au–semi-insulating GaAs contact investigated by positron-lifetime technique

Positron-lifetime spectroscopy has been used to investigate the electric-field distribution occurring at the Au–semi-insulating GaAs interface. Positrons implanted from a 22Na source and drifted back to the interface are detected through their characteristic lifetime at interface traps. The relative intensity of this fraction of interface-trapped positrons reveals that the field strength in the depletion region saturates at applied biases above 50 V, an observation that cannot be reconciled with a simple depletion approximation model. The data, are, however, shown to be fully consistent with recent direct electric-field measurements and the theoretical model proposed by McGregor et al. [J. Appl. Phys. 75, 7910 (1994)] of an enhanced EL2+ electron-capture cross section above a critical electric field that causes a dramatic reduction of the depletion region’s net charge density. Two theoretically derived electric field profiles, together with an experimentally based profile, are used to estimate a positron mobility of ∼95±35 cm2 V-1 s-1 under the saturation field. This value is higher than previous experiments would suggest, and reasons for this effect are discussed.published_or_final_versio

Efficacy of a Novel Injection Lipolysis to Induce Targeted Adipocyte Apoptosis: A Randomized, Phase IIa Study of CBL-514 Injection on Abdominal Subcutaneous Fat Reduction

Background: CBL-514 is a novel injectable drug that may be safe and efficacious for localized abdominal subcutaneous fat reduction. Objectives: The aim of this study was to assess the safety and efficacy of CBL-514 in reducing abdominal subcutaneous fat volume and thickness. Methods: This Phase IIa, open-label, random allocation study consisted of a 6-week treatment period and follow-up at 4 and 8 weeks following the last treatment. Participants were randomly allocated to receive 1.2 mg/cm2 (180 mg), 1.6 mg/cm2 (240 mg), or 2.0 mg/cm2 (300 mg) of CBL-514 with up to 4 treatments, each comprising 60 injections into the abdominal adipose layer. Changes in abdominal subcutaneous fat were assessed by ultrasound at follow-up visits. Treatment-emergent adverse events were recorded. Results: Higher doses of CBL-514 (unit dose, 2.0 and 1.6 mg/cm2) significantly improved the absolute and percentage reduction in abdominal fat volume (P < 0.00001) and thickness (P < 0.0001) compared with baseline. Although the COVID-19 pandemic halted some participant recruitment and follow-ups, analysis was unaffected, even after sample size limitations. Conclusions: CBL-514 injection at multiple doses up to 300 mg with a unit dose of 2.0 mg/cm2 is safe, well-tolerated, and reduced abdominal fat volume and thickness by inducing adipocyte apoptosis. Although other procedures exist to treat abdominal fat, they have limitations and may cause complications. At a dose of 2.0 mg/cm2, CBL-514 safely and significantly reduced abdominal fat volume by 24.96%, making it a promising new treatment for routine, nonsurgical abdominal fat reduction in dermatologic clinics. Level of Evidence: 4

Deep level defects in a nitrogen-implanted ZnO homogeneous p-n junction

Nitrogen ions were implanted into undoped melt grown ZnO single crystals. A light-emitting p-n junction was subsequently formed by postimplantation annealing in air. Deep level transient spectroscopy was used to investigate deep level defects induced by N+ implantation and the effect of air annealing. The N+ implantation enhanced the electron trap at E C -(0.31±0.01) eV (E3) and introduced another one at E C -(0.95±0.02) eV (D1), which were removed after annealing at 900 and 750 °C, respectively. Another trap D2 (Ea =0.17±0.01 eV) was formed after the 750 °C annealing and persisted at 1200 °C. © 2008 American Institute of Physics.published_or_final_versio

Solution-based growth of ZnO nanorods for light-emitting devices: Hydrothermal vs. electrodeposition

ZnO nanorods have been grown by two inexpensive, solution-based, low-temperature methods: hydrothermal growth and electrodeposition. Heterojunction n-ZnO nanorods/p-GaN light-emitting diodes have been studied for different nanorod growth methods and different preparation of the seed layer. We demonstrate that both the nanorod properties and the device performance are strongly dependent on the growth method and seed layer. All the devices exhibit light emission under both forward and reverse bias, and the emission spectra can be tuned by ZnO nanorod deposition conditions. Electrodeposition of rods or a seed layer results in yellow emission, while conventional hydrothermal growth results in violet emission. © The Author(s) 2010. This article is published with open access at Springerlink.com.published_or_final_versionSpringer Open Choice, 01 Dec 201

Plasma high sensitivity troponin T levels in adult survivors of childhood leukaemias: determinants and associations with cardiac function

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CXCL10/CXCR3 signaling mobilized-regulatory T cells promote liver tumor recurrence after transplantation

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High Frequency of CD4+CXCR5+ TFH Cells in Patients with Immune-Active Chronic Hepatitis B

BACKGROUND: T follicular helper (TFH) cells are a special subpopulation of T helper cells and can regulate humoral immune responses. This study examined whether the frequency of CD4(+)CXCR5(+) TFH cells could be associated with active immunity in chronic hepatitis B (CHB) patients. METHODOLOGY AND FINDINGS: The frequencies of peripheral blood CD4(+)CXCR5(+) TFH cells, inducible T cell costimulator (ICOS), and/or programmed death 1 (PD-1) positive CD4(+)CXCR5(+) TFH cells in immune-active (IA), immune-tolerant (IT) CHB, and healthy controls (HC) were characterized by flow cytometry analysis. The effect of adevofir dipivoxil treatment on the frequency of CD4(+)CXCR5(+) TFH cells, the concentrations of serum IL-2, IFN-γ, TNF-α, IL-4, IL-6, IL-10, IL-21, ALT, AST, HBsAg, HBsAb, HBeAg, HBeAb and HBV loads in IA patients were determined. The potential association of the frequency of CD4(+)CXCR5(+) TFH cells with clinical measures was analyzed. In addition, the frequency of splenic and liver CD4(+)CXCR5(+) TFH cells in HBV-transgenic mice was examined. We found that the frequency of CD4(+)CXCR5(+) TFH cells in IA patients was significantly higher than that of IT patients and HC, and the percentages of CD4(+)CXCR5(+) TFH in IA patients were positively correlated with AST. Furthermore, the percentages of ICOS(+), PD-1(+), and ICOS(+)PD-1(+) in CD4(+)CXCR5(+) TFH cells in CHB patients were significantly higher than that of HC. Treatment with adefovir dipivoxil reduced the frequency of CD4(+)CXCR5(+) TFH, PD-1(+)CD4(+)CXCR5(+) TFH cells and the concentrations of HBsAg and HBeAg, but increased the concentrations of HBsAb, HBeAb, IL-2 and IFN-γ in IA patients. Moreover, the frequency of splenic and liver CD4(+)CXCR5(+) TFH cells in HBV-transgenic mice was higher than that of wild-type controls. CONCLUSIONS: These data indicate that CD4(+)CXCR5(+) TFH cells may participate in the HBV-related immune responses and that high frequency of CD4(+)CXCR5(+) TFH cells may be a biomarker for the evaluation of active immune stage of CHB patients

Structure of hadron resonances with a nearby zero of the amplitude

We discuss the relation between the analytic structure of the scattering amplitude and the origin of an eigenstate represented by a pole of the amplitude.If the eigenstate is not dynamically generated by the interaction in the channel of interest, the residue of the pole vanishes in the zero coupling limit. Based on the topological nature of the phase of the scattering amplitude, we show that the pole must encounter with the Castillejo-Dalitz-Dyson (CDD) zero in this limit. It is concluded that the dynamical component of the eigenstate is small if a CDD zero exists near the eigenstate pole. We show that the line shape of the resonance is distorted from the Breit-Wigner form as an observable consequence of the nearby CDD zero. Finally, studying the positions of poles and CDD zeros of the KbarN-piSigma amplitude, we discuss the origin of the eigenstates in the Lambda(1405) region.Comment: 7 pages, 3 figures, v2: published versio

The regulatory mechanism of fungal elicitor-induced secondary metabolite biosynthesis in medical plants.

A wide range of external stress stimuli trigger plant cells to undergo complex network of reactions that ultimately lead to the synthesis and accumulation of secondary metabolites. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Throughout evolution, endophytic fungi, an important constituent in the environment of medicinal plants, have known to form long-term stable and mutually beneficial symbiosis with medicinal plants. The endophytic fungal elicitor can rapidly and specifically induce the expression of specific genes in medicinal plants which can result in the activation of a series of specific secondary metabolic pathways resulting in the significant accumulation of active ingredients. Here we summarize the progress made on the mechanisms of fungal elicitor including elicitor signal recognition, signal transduction, gene expression and activation of the key enzymes and its application. This review provides guidance on studies which may be conducted to promote the efficient synthesis and accumulation of active ingredients by the endogenous fungal elicitor in medicinal plant cells, and provides new ideas and methods of studying the regulation of secondary metabolism in medicinal plants