Single step thermal treatment synthesis and characterization of lithium tetraborate nanophosphor

This study includes the synthesis of nano-sized lithium tetraborate by an innovative single step thermal treatment method and characterization of the products. The heating temperature for the synthesis was varied between 200 and 850 °C with the retention time of 2 h. Polyvinyl pyrrolidone (PVP) with different concentrations was used as surfactant. Characterization of the samples was achieved by thermogravimetric analysis (TGA), derivative thermogravimetry analysis (DTG), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) techniques and UV–vis spectroscopy. Thermal analysis of initial solution allowed the optimization of the heat treatment program and showed that the thermal stability of samples is started at 460 °C. FT-IR, XRD and TEM results proved the formation of pure nano-crystalline lithium tetraborate at temperature between 460 and 750 °C. Furthermore, the band gap investigation was performed using UV–vis spectra in the presence of different concentrations of PVP and in variety of calcination temperatures. The estimated optical bandgap was found to be between 5.2 and 6.2 eV

Structural, optical and electrical properties of ZnS nanoparticles affecting by organic coating

In this study the influence of the organic polymeric coating and its concentration on the structural, optical and electrical properties of ZnS nanocrystals has been investigated. In this matter, PVP-capped ZnS nanocrystals were prepared by a simple, rapid and energy efficient microwave method. The XRD results confirmed the formation of single phase cubic nano crystalline structure. TEM images showed the formation of well isolated spherical nanoparticles with the average size of less than 5.5 nm. The presence of tensile strain in all samples was determined from Williamson-Hall analysis. The elemental compositions of Zn, S and O were quantitatively obtained from EDX analysis, where the FT-IR spectra confirmed coordination with O atoms of PVP. The band gap and absorption edge shift was determined using UV–visible spectroscopy. The PL spectra of the PVP-capped ZnS nanoparticles appeared broadened from 370 to 500 nm due to the presence of multiple emission bands attribute to the sulfur and zinc vacancies or compounded effect of PVP. The electrical property study of samples indicated the conductivity enhancement from 2.981×10-6 to 7.014 ×10-6 S/m by increasing PVP concentration. Increasing of dielectric constant and decrease in the peak value of tan δ by raising the PVP concentration were observed

Numerical study of side gate junction-less transistor in on state

Side gate p-type Junctionless Silicon transistor is fabricated by AFM nanolithography on low-doped (105 cm-3) SOI wafer. In this work, the simulation characteristic of the device using TCAD Sentaurus in on state will be studied. The results show that the device is the pinch off transistor, works in on state for zero gate voltage in depletion mode. Negative gate voltage drives the device into on state, but unable to make significant effect on drain current as accmulation mode. Simulation results for valence band energy, electric field and hole density are investigated along the active regions. The influence of the electric field due to the applied voltages of V DS and V G on charge distribution is much more when the device operates at the saturation region. The hole quasi-Fermi level has a positive slope showing the current flows from source to drain

Atomic force microscope base nanolithography for reproducible micro and nanofabrication

Atomic force microscopy nanolithography (AFM) is a strong fabrication method for micro and nano structure due to its high spatial resolution and positioning abilities. Mixing AFM nanolithography with advantage of silicon-on-insulator (SOI) technology provides the opportunity to achieve more reliable Si nanostructures. In this letter, we try to investigate the reproducibility of AFM base nanolithography for fabrication of the micro/nano structures. In this matter local anodic oxidation (LAO) procedure applied to pattern a silicon nanostructure on p-type (1015 cm-3) SOI using AFM base nanolithography. Then chemical etching is applied, as potassium hydroxide (saturated with isopropyl alcohol) and hydrofluoric etching for removing of Si and oxide layer, respectively. All parameters contributed in fabrication process were optimized and the final results revealed a good potential for using AFM base nanolithography in order to get a reproducible method of fabrication

Comparison of colchicine versus prednisolone in recurrent aphthous stomatitis: A double-blind randomized clinical trial

Purpose: Recurrent aphthous stomatitis (RAS) is one of the most common ulcers of the oral cavity with a reported prevalence of 5- 50%. There is still no definitive treatment for RAS; however, immunosuppressive and immunomodulant agents have been proposed. In this study, we compared the therapeutic effects of 5 mg/d prednisolone with 0.5 mg/d colchicine in the treatment of RAS. Methods: In a double-blind randomized clinical trial, 34 patients with RAS were randomly divided into two groups for treatment with prednisolone or colchicine. All patients took the medication for three months and were assessed at two weeks intervals. The groups were compared for size and number of lesions, severity of pain and burning sensation, duration of pain-free episodes and any side effects of the prescribed medicines. Both colchicine and prednisolone treatments significantly reduced RAS (p < 0.001). No significant differences in size and number of lesions, recurrence and severity of pain and duration of pain-free period were seen between the two treatment groups. Colchicine (52.9%) had significantly more side effects than prednisolone (11.8%). Conclusion: Low dose prednisolone and colchicine were both effective in treating RAS. Given that the two therapies had similar efficacy, yet colchicine was associated with more side effects, , 5mg/d of prednisolone seems to be a better alternative in reducing the signs and symptoms of the disease

Formation and characterization of ultrafine nanophosphors of lithium tetraborate (Li2B4O7) for personnel and medical dosimetry

The present study demonstrates an innovative single-step thermal synthesis of nano-sized lithium tetraborate dosimeter and its characterization. The optimum calcination temperature and time for the synthesis of the nanoparticles material was 750 °C and 2 h, respectively. Characterization of the samples was carried out using X-ray diffractometry (XRD), Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), and thermoluminescence (TL). FT-IR, XRD and TEM results confirmed the formation of pure nano-crystalline lithium tetraborate. The product showed a linear response over a wide range of doses from 10−1 to 1.5 × 102 Gy. Moreover, the samples illustrate non-energy dependence among a wide range energy interval from 24 keV up to 1250 keV and almost no fading during one month storage

Search for stealth supersymmetry in final states with two photons, jets, and low missing transverse momentum in proton-proton collisions at s\sqrt{s} = 13 TeV

International audienceThe results of a search for stealth supersymmetry in final states with two photons and jets, targeting a phase space region with low missing transverse momentum ($p_\text{T}^\text{miss}$), are reported. The study is based on a sample of proton-proton collisions at $\sqrt{s}$ =13 TeV collected by the CMS experiment, corresponding to an integrated luminosity of 138 fb$^{-1}$. As LHC results continue to constrain the parameter space of the minimal supersymmetric standard model, the low $p_\text{T}^\text{miss}$ regime is increasingly valuable to explore. To estimate the backgrounds due to standard model processes in such events, we apply corrections derived from simulation to an estimate based on a control selection in data. The results are interpreted in the context of simplified stealth supersymmetry models with gluino and squark pair production. The observed data are consistent with the standard model predictions, and gluino (squark) masses of up to 2150 (1850) GeV are excluded at the 95% confidence level