PRDC--a software package for personnel radiation dose calculation

To determine effective dose, we usually need to use a very complicated human body model and a sophisticated computer code to transport radiations in the body model and surrounding medium, which is not very easy to practicing health physicists in the field. This study develops and tests a software package, called PRDC (Personnel Radiation Dose Calculation), which calculates effective dose and radiation doses to various organs/tissues and personal dosemeters based on a series of interpolations.     

Biosorption of lead, copper and cadmium by an indigenous isolate Enterobacter sp. J1 possessing high heavy-metal resistance

This study was undertaken to investigate biosorption kinetics and equilibria of lead (Pb), copper (Cu) and cadmium (Cd) ions using the biomass of Enterobacter sp. J1 isolated from a local industry wastewater treatment plant. Efficiency of metal ion recovery from metal-loaded biomass to regenerate the biosorbent was also determined. The results show that Enterobacter sp. J1 was able to uptake over 50mg of Pb per gram of dry cell, while having equilibrium adsorption capacities of 32.5 and 46.2mg/g dry cell for Cu and Cd, respectively. In general, Langmuir and Freundlich models were able to describe biosorption isotherm fairly well, except that prediction of Pb adsorption was relatively poor with Langmuir model, suggesting a different mechanism for Pb biosorption. Adjusting the pH value to 3.0 led to nearly complete desorption of Cd from metal-loaded biomass, while over 90% recovery of Pb and Cu ions was obtained at pH相似文献   

Effect of moisture on H(2)S adsorption by copper impregnated activated carbon

The aim of this study is to investigate the effect of moisture on adsorption efficiency of hydrogen sulfide (H(2)S) by impregnated activated carbon (IAC). Copper(II) nitrate was used as an impregnant. Two humidification conditions of IAC, pre-moistened and gas stream containing moisture, were studied. The experimental results revealed that the copper species onto the IAC was suggested to be Cu(OH)(2) that deposited on activated carbon during the impregnation process. The adsorption mechanism of H(2)S by copper impregnated IAC was proposed, involving physic-sorption and chemical reactions. Moreover, the H(2)S breakthrough capacity decreased with increasing the relative humidity of gas stream. The causes were attributed to three points as follow: the competition adsorption occurred between moisture and H(2)S; the copper(II) species reduced to copper(I) species leading to IAC deactivation; and the rate of chemical reaction restrained by moisture.     

Arsenic inhibits induction of cytochrome P450 1A1 by 2,3,7,8-tetrachlorodibenzo-p-dioxin in human hepatoma cells

The aim of this study was to examine the arsenic effect on activation of aryl hydrocarbon receptor (AhR)-mediated gene expression by 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) in human hepatoma cells. The human hepatoma Huh7 cells were treated with sodium arsenite (NaAsO2) from 0.5 to 20 microM for 24 h. Our data revealed that NaAsO2 < or = 10 microM caused no significant cytotoxic effect on Huh7 cells (p>0.05). We also established a dioxin-responsive element (DRE)-mediated Chemical Activated LUciferase eXpression (CALUX) cell line, Huh7-DRE-Luc, by stable transfection of Huh7 with a DRE-driven firefly luciferase reporter plasmid (4xDRE-TATA-Luc). Treatments of Huh7-DRE-Luc and Huh7 with NaAsO2 attenuated the 2,3,7,8-TCDD-induced DRE-CALUX and cytochrome P450 1A1 (CYP1A1) activations, respectively, in a dose-dependent manner. We found that the calculated CALUX-toxic equivalent (TEQ) levels induced by cotreatment of NaAsO2 > or = 3.0 microM and 10 nM 2,3,7,8-TCDD were significantly lower than that induced by 2,3,7,8-TCDD alone (p<0.05). In the present study, we demonstrated that arsenic not only inhibited the TCDD-induced CYP1A1 activation but also interfered with DRE-CALUX bioassay in human hepatoma cells. Our finding also suggests that extensive cleanup of sample for removal of any possible interfering factor is critical to guarantee the accuracy of dioxin-TEQ levels using DRE-CALUX bioassay.     

The effect of erbium on the adsorption and photodegradation of orange I in aqueous Er3+-TiO2 suspension

Pure TiO(2) and erbium ion-doped TiO(2) (Er(3+)-TiO(2)) catalysts prepared by the sol-gel method were characterized by means of XRD and diffusive reflectance spectra (DRS). The XRD results showed that erbium ion doping could enhance the thermal stability of TiO(2) and inhibit the increase of the crystallite size, and the DRS results showed that the optical absorption edge slightly shifted to red direction owing to erbium ion doping and the Er(3+)-TiO(2) catalysts had three typical absorption peaks located at 490, 523 and 654 nm owing to the transition of 4f electron from (4)I(15/2) to (4)F(7/2), (2)H(11/2) and (4)F(9/2). With a purpose of azo dyes degradation, orange I was used as a model chemical. And the adsorption isotherm, degradation and mineralization of orange I were investigated in aqueous suspension of pure TiO(2) or Er(3+)-TiO(2) catalysts. The results showed that Er(3+)-TiO(2) catalysts had higher adsorption equilibrium constants and better adsorption capacity than pure TiO(2). The adsorption equilibrium constants (K(a)) of Er(3+)-TiO(2) catalysts were about twice of that of pure TiO(2). The maximum adsorption capacity (Q(max)) of 2.0% Er(3+)-TiO(2) catalyst was 13.08x10(-5)mol/g, which was much higher than that of pure TiO(2) with 9.03x10(-5)mol/g. Among Er(3+)-TiO(2) catalysts, 2.0% Er(3+)-TiO(2) catalyst achieved the highest Q(max) and K(a) values. The kinetics of the orange I degradation using different Er(3+)-TiO(2) catalysts were also studied. The results demonstrated that the degradation and mineralization of orange I under both UV radiation and visible light were more efficient with Er(3+)-TiO(2) catalyst than with pure TiO(2), and an optimal dosage of erbium ion at 1.5% achieved the highest degradation rate. The higher photoactivity under visible light might be attributable to the transitions of 4f electrons of Er(3+) and red shifts of the optical absorption edge of TiO(2) by erbium ion doping.     

Visible-light-responsive nano-TiO(2) with mixed crystal lattice and its photocatalytic activity

Ultraviolet-?and visible-light-responsive titania-based photocatalysts were synthesized and employed in the photocatalytic oxidation of NO(x). Sol-gel processes using tetrabutyl orthotitanate and ethanol under acid catalyzed condition and controlled calcination were performed to synthesize titanium dioxide with a mixed crystal lattice of anatase, brookite and rutile phases. The TiO(2) prepared under calcination at 200?°C exhibited high photocatalytic activity for degradation of NO(x) under both ultraviolet (UV) and visible-light illumination. The experimental results showed that up to 70% removal of NO(x) could be obtained in a continuous flow type reaction system under irradiation with visible light. The calcination temperature has an important influence on the particle size and lattice structure of TiO(2). It is also found that the peculiar mixed-phase structure of TiO(2), evidenced from Raman, x-ray diffractometry (XRD), and UV-vis spectroscopy, was inferred to be an important factor for visible-light absorption and NO(x) removal activity under a wide range of visible-light illumination.     

Geometrically tuned and chemically switched wetting properties of silicon nanotips

The wetting properties of silicon nanotips (SiNTs) are discussed. SiNTs were prepared by single step dry etching of silicon wafers in an electron cyclotron resonance plasma of silane, methane, argon and hydrogen and water contact angles were measured as a function of their aspect ratio (α) and the inter-tip distance. The hydrophilic nature of the SiNTs is tunable with α and the inter-tip distance. Super-hydrophilicity with water contact angles close to 2° was observed with α>12 (length ～1500?nm). Upon coating a 1500?nm long SiNT with TiO(2), the water contact angle jumped from 2° to ～140°, demonstrating a switchover from super-hydrophilic to hydrophobic surface properties.     

Efficiency of a grazing-incidence off-plane grating in the soft-x-ray region

Efficiency measurements of a grazing-incidence diffraction grating in the off-plane mount were performed using polarized synchrotron radiation. The grating had 5000 grooves/mm, an effective blaze angle of 14 degrees, and was gold coated. The efficiencies in the two polarization orientations (TM and TE) were measured in the 1.5-5.0 nm wavelength range and were compared with the efficiencies calculated using the PCGrate-SX code. The TM and TE efficiencies differ, offering the possibility of performing unique science studies of astrophysical, solar, and laboratory sources by exploiting the polarization sensitivity of the off-plane grating.     

Using data linkage to generate 30-day crash-fatality adjustment factors for Taiwan

Different countries have their own police reporting time standards for counting the number of fatalities in reported crashes. A rapid estimation method (such as adjustment factor) for the comparison is important. The data-linkage technique was used to combine police-reported crash data and vital registration data, in order to generate 30-day fatality adjustment factors for various reporting time standards, which could also shed light on the fatal injury trend over time. The major findings were as follows. Firstly, a conservative 30-day fatality adjustment factor for the first day (or 24 h) would be 1.54 (or 1.35) in an area with a large motorcycle population, like Taiwan. This produced 20-40% higher 30-day fatalities than UK Transport Research Laboratory predicted, and 15-25% higher fatalities than those in Europe/Japan. Secondly, after excluding motorcycle impacts, the Taiwanese factors suggested 8-14% higher fatalities within 30 days than those in Europe/Japan. Third, motorcycle fatalities influenced the overall 30-day fatality trend within 3 days. In the future, both the police under-reporting problem and the motorcycle/overall fatal injury pattern within 3 days after crashing in developing countries like Taiwan merit further investigation.     

Screening of nerve agent degradation products by MALDI-TOFMS

A novel method for the rapid screening of degradation products derived from nerve agents by matrix-assisted laser desorption ionization time-of-flight mass spectrometry is described. Five standard products were selected as model compounds, including isopropyl methylphosphonic acid (IMPA), pinacolyl methylphosphonic acid (PMPA), ethyl methylphosphonic acid (EMPA), isobutyl methylphosphonic acid (i-BuMPA), and cyclohexyl methylphosphonic acid (CHMPA), which are degradation products of Sarin (GB), Soman (GD), VX, Russian VX (RVX), and GF, respectively. For comparison, CHCA (alpha-cyano-4-hydroxycinnamic acid) and DCCA (7-(diethylamino)coumarin-3-carboxylic acid) were used as the MALDI-matrix when the third harmonic generation (355 nm) of a Nd:YAG laser and a hydrogen Raman laser (multifrequency laser) were used, respectively. The method permitted the five nerve agent degradation products to be screened rapidly and successfully, suggesting that it has the potential for use as a routine monitoring tool.