Calculation of the Effective Stopping Power of Ions Generated by Neutrons in Tissue Constituents

This paper reports the calculation of stopping powers of heavy charged particles generated by neutrons in four-element tissue constituents for particle energies from 0.1 keY to 1.0 MeV. At low projectile energies of less than 30 keV/amu where the nuclear stopping phenomenon is more dominant than the electronic stopping phenomenon, the effective stopping power values are higher than the continuous slowing-down approximation (CSDA) values, from which the deviation is dependent upon the target mass and the energy and mass of the projectiles

Simulation of transport in laterally gated junctionless transistors fabricated by local anodization with an atomic force microscope

In this paper, we have investigated the characteristics and transport features of junctionless lateral gate transistors via measurement and simulations. The transistor is fabricated using an atomic force microscopy (AFM) nanolithography technique on silicon-on-insulator (SOI) wafer. This work develops our previous examination of the device operation by using 3D numerical simulations to offer a better understanding of the origin of the transistor operation. We compare the experimental measurements and simulation results in the transfer characteristic and drain conductance. We also explore the behavior of the device in on and off states based on the variation of majority and minority carriers' density, electric-field components, and recombination/generation rate of carriers in the active region of the device. We show that the device is a normally on device that can force the current through a depleted region (off state) and uses bulk conduction instead of surface conduction. We also found that due to the lateral gate design, low-doped channel, and lack of the gate oxide the electrostatic squeezing of the channel effectively forces the device into the off state, but the current improvement by accumulation of carriers is not significant

Microwave-Assisted Synthesis of Porous ZnO/SnS 2

Porous ZnO/SnS2 nanocomposites with adjustable SnS2 contents were prepared via microwave-assisted heating of different aqueous solutions of SnS2 precursors in the presence of fixed amount of ZnCO3 nanoparticles at pH 7. The structures, compositions, BET specific surface areas, and optical properties of the as-prepared products were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy, N2 adsorption, and UV-Vis absorption spectra. Photocatalytic activities of the samples were tested by the removal of aqueous ciprofloxacin, CrVI, and methylene blue under visible-light (λ>420 nm) irradiation. The experimental results reveal that the as-prepared heterogeneous nanostructures exhibit much higher visible-light-driven photocatalytic activity for the degradation of the pollutants than pure SnS2 nanocrystals. The photocatalytic degradation rates Ct/C0 of the pollutants for the most active heterogeneous nanostructure are about 10, 49, and 9 times higher than that of pure SnS2. The enhanced photocatalytic activities exhibited by the heterojunctions could be ascribed to the synergetic effect of enhanced absorption in the visible region and the reduced rate of charge carrier recombination because of efficient separation and electron transfer from the SnS2 to ZnO nanoparticles

Synthesis, characterization and nonlinear optical properties of silver/PVA nanocomposites

Silver/polyvinyl alcohol (PVA) nanocomposites are prepared via quick precipitation method, using hydrazine as a reducing agent. Preparing of silver/PVA nanocomposites by this method is done for the first time. The samples are characterized by Uv-Visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM). Nonlinear optical properties are carried out by Z-scan technique using a blue CW laser beam operated at wavelength 405 nm. It is shown that the synthesized samples have negative nonlinear refractive index and the magnitude is in the order of 10^-8. The nonlinear refractive index increases as amount of reducing agent increases

Synthesis of CdS Sensitized TiO 2

A series of CdS/TiO2 nanocomposites with different Cd to Ti molar ratio were synthesized from P25-TiO2 nanopowder using microwave-assisted hydrothermal method. The as-produced powders were characterized by XRD, electron microscopy, EDX, and UV-Vis diffuse reflectance spectroscopy. The adsorption capacity and photocatalytic activity of the samples were investigated using methylene blue as a model pollutant. Sorption tests revealed that the adsorption of MB onto the samples obeys the Freundlich-Langmuir isotherm model. The sorption capacity decreased as follows: TiO2>TCd2>TCd1>TCd3>TCd4. The results of the photocatalytic tests under high-intensity discharge (HID) lamp revealed that CdS/TiO2 powders with low Cd to Ti molar ratios exhibited much higher activities than P25-TiO2. The CdS/TiO2 sample with 20% CdS/(TCd2) showed the most activity among all these samples. The results also show that the Cd to Ti molar ratio of the nanocomposite has a significant effect on the photodegradation of MB and the enhanced activities exhibited by the nanocomposites are because of the low rate of electron-hole recombination

Effect of reaction time on structural and optical properties of porous SiO2 nanoparticles

The effect of different reaction time on the structural and optical properties of porous SiO2 nanoparticles by simple precipitation method was comprehensively studied in this work. In this study, an aqueous sodium silicate was reacted with ethanol in deionized water and stirred between 30 to 180 min as for mixture to react. The filtered product was subjected to drying and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared reflection (FTIR), surface area analyzer, Raman and UV-Vis spectroscopy. The produced SiO2 nanoparticles powder was in amorphous form with the average particle size less than 100 nm. The sample with reaction time 90 min shows fine porous characteristic with the highest specific surface area and average pore volume. This different characteristic also gives a significant change in optical properties of the final product

A facile synthesis of amorphous silica nanoparticles by simple thermal treatment route

A facile thermal treatment route was for the first time used to successfully synthesize amorphous silica nanoparticles. Various techniques were employed to study the structural, phase and elemental composition of the material at different calcination temperature between 500-750oC. The XRD analysis confirms the formation silica to be in an amorphous state and further revealed that the material remained in amorphous state even when calcined at 750oC. The FT-IR spectra shows that the calcination process has enable the removal of organic source from PVP and formation of amorphous silica nanoparticles. The average particle size of the material estimated from the TEM images shows that the particle were <10nm. The optical absorbance exhibited in the UV region reveals amorphous silica nanoparticles possess a wide band gap ranging from 3.803-4.126eV calcined between 500 to 750oC. The EDX analysis has confirmed the presence of Si and O as the only elements in the material formed, which implies thermal treatment method is effective for the synthesis of amorphous silica nanoparticles

Type 2 Diabetes as a Risk Factor for Dementia in Women Compared With Men:A Pooled Analysis of 2.3 Million People Comprising More Than 100,000 Cases of Dementia

OBJECTIVE: Type 2 diabetes confers a greater excess risk of cardiovascular disease in women than in men. Diabetes is also a risk factor for dementia, but whether the association is similar in women and men remains unknown. We performed a meta-analysis of unpublished data to estimate the sex-specific relationship between women and men with diabetes with incident dementia. RESEARCH DESIGN AND METHODS: A systematic search identified studies published prior to November 2014 that had reported on the prospective association between diabetes and dementia. Study authors contributed unpublished sex-specific relative risks (RRs) and 95% CIs on the association between diabetes and all dementia and its subtypes. Sex-specific RRs and the women-to-men ratio of RRs (RRRs) were pooled using random-effects meta-analyses. RESULTS: Study-level data from 14 studies, 2,310,330 individuals, and 102,174 dementia case patients were included. In multiple-adjusted analyses, diabetes was associated with a 60% increased risk of any dementia in both sexes (women: pooled RR 1.62 [95% CI 1.45-1.80]; men: pooled RR 1.58 [95% CI 1.38-1.81]). The diabetes-associated RRs for vascular dementia were 2.34 (95% CI 1.86-2.94) in women and 1.73 (95% CI 1.61-1.85) in men, and for nonvascular dementia the RRs were 1.53 (95% CI 1.35-1.73) in women and 1.49 (95% CI 1.31-1.69) in men. Overall, women with diabetes had a 19% greater risk for the development of vascular dementia than men (multiple-adjusted RRR 1.19 [95% CI 1.08-1.30]; P &lt; 0.001). CONCLUSIONS: Individuals with type 2 diabetes are at ~60% greater risk for the development of dementia compared with those without diabetes. For vascular dementia, but not for nonvascular dementia, the additional risk is greater in women