湖北省国控点天然γ辐射空气吸收剂量率研究

使用我国新一代X-γ剂量率测量仪对湖北省9个国控点进行了天然γ辐射空气吸收剂量率的测量,建立了剂量率与剂量当量的数学模型,计算了9个国控点地区人均年有效剂量当量。结果表明,9个国控点地区的剂量率在59.336～141.638 nGy/h,天然γ辐射致公众人均年有效剂量当量为0.390～0.931 mSv;9个国控点地区天然γ辐射均属正常天然本底水平。     

Effect of Irradiation Absorbed Dose and Organic Solvent on the Grafting Rate of PVDF-g-PHEMA through Gamma-ray Irradiation in a Homogenous Solution

High Energy Chemistry - Modification of Polyvinylidene fluoride (PVDF) by radiation grafting is a research hotspot in recent years. In this study, the monomer 2-Hydroxyethyl methacrylate (HEMA) was...     

The Effect of Carbonate Soil on Transport and Dose Estimates for Long-Lived Radionuclides at a U.S. Pacific Test Site

The United States conducted a series of nuclear tests from 1946 to 1958 at Bikini, a coral atoll, in the Marshall Islands (MI). The aquatic and terrestrial environments of the atoll are still contaminated with several long-lived radionuclides that were generated during testing. The four major radionuclides found in terrestrial plants and soils are cesium-137, strontium-90, plutonium-239+240 and americium-241. Cesium-137 in the coral soils is more available for uptake by plants than ¹³⁷Cs associated with continental soils of North America or Europe. Soil-to-plant ¹³⁷Cs median concentration ratios (CR) (kBq·kg^-1 dry weight plant/kBq·kg^-1 dry weight soil) for tropical fruits and vegetables range between 0.8 and 36, much larger than the range of 0.005 to 0.5 reported for vegetation in temperate zones. Conversely, ⁹⁰Sr median CRs range from 0.006 to 1.0 at the atoll versus a range from 0.02 to 3.0 for continental silica-based soils. Thus, the relative uptake of ¹³⁷Cs and ⁹⁰Sr by plants in carbonate soils is reversed from that observed in silica-based soils. The CRs for ^239+240Pu and ²⁴¹Am are very similar to those observed in continental soils. Values range from 10^-6 to 10^-4 for both ^239+240Pu and ²⁴¹Am. No significant difference is observed between the two in coral soil. The uptake of ¹³⁷Cs by plants is enhanced because of the absence of mineral binding sites and the low concentration of potassium in the coral soil. Cesium-137 is bound to the organic fraction of the soil, whereas ⁹⁰Sr, ^239+240Pu and ²⁴¹Am are primarily bound to soil particles. Assessment of plant uptake for ¹³⁷Cs and ⁹⁰Sr into locally grown food crops was a major contributing factor in: (1) reliably predicting the radiological dose for returning residents and (2) developing a strategy to limit the availability and uptake of ¹³⁷Cs into locally grown food crops.     

Radionuclides migration in the geosphere and their sorption on natural sorbents

This report identifies a number of mechanisms that retard radionuclide migration, describes methods that are used to study such retardation phenomena and evaluates the extent to which this methods may be used to diagnose radionuclide migration through various types of geologic media. A qualitative, quantitative and applicable basis for ion exchange modelling in clay have provided. Caesium and strontium are taken as a reference elements, and itsK _d values obtained from both batch and diffusion experiments are explained and independently predicted by the model.     

Influence of Air Velocity,Application Dose,and Test Area Size on the Volatilisation of Lindane

Abstract

The volatilisation of lindane from soil and French beans was tested in a wind tunnel under defined conditions. Volatilised lindane was determined directly by passing a partial air stream through an adsorbent. Applications of a lindane formulation onto soil and plant surfaces were performed using a moving nozzle.

Soil volatilisation experiments were conducted using different air velocities (0.4, 1.1, 1.7 m/s). At higher air velocities the volatilisation rate increased from 12% to 31% within 24 h (initial dose 100%). For plant experiments with different velocities (0.4,1.0,2.0 m/s) the volatilisation rate increased from 52% to 62% at the highest velocity. Additionally, as higher air velocities were applied, air concentrations of lindane during the first hour decreased from 1.61 μg/m3 at 0.4 m/s to 0.61 μg/m3 at 2.0 m/s.

In soil experiments with different application doses of lindane (33 mg/m², 117 mg/m²) the volatilisation rate was decreased (23%) at the higher application dose in comparison to the lower dose (39%). The volatilisation rate was also influenced by the size of the treated area in the wind tunnel. From a larger soil surface (0.84 m2) a lower amount of lindane (23%) volatilised than from a smaller surface (31% at 0.28 m).     

Analysis of Phthalate Esters in Air,Soil and Plants in Plastic Film Greenhouse

The phthalate esters such as MDP,DEP,BDP and DEHP in air,soil and plant smples in plastic film greenhouse were clean up with fine silica gel column and determined with HPLC.It was found that the concentrations of PEs in ari and soil samples in plastic film greenhouse are much higher than those of contrast samples. But concentration of PEs in plants in plastic film greenhouse are not remarkably affected by the pollution of air and soil.     

Direct Measurement of Ammonia in Ambient Air

Abstract

A model is proposed which addresses the factors involved in the axial light attenuation of a coated waveguide (collector/sensor) whose polymer coating has been sensitized to ammonia. The experimental results appear to corroborate the model predictions of high sensitivity (ppb) and independence of sample flow on the collector/sensor. Concentration and relative humidity both determine the slopes of the transmission curves, the latter factor of which can be reduced to a second order effect by controlling the relative humidity in the sample holder.     

LC Assay of Eletriptan in Tablets and In Vitro Dissolution Studies

Eletriptan (ELT) is a new selective serotonin agonist approved for the treatment of acute migraine headaches. A simple and rapid liquid chromatographic method was developed and validated for the assay of ELT in tablets. Chromatography was carried out on a 250 mm × 4.6 mm C₁₈ column at 30 °C. Acetonitrile–15 mM triethylamine solution (adjusted to pH 7.0 using concentrated o-phosphoric acid) (60:40, v/v) mixture was used as mobile phase at 1.0 mL min^?1 flow rate and UV detector was set at 225 nm. A linear response (r ²  = 0.9999) was observed in the range of 0.1–1.6 μg mL^?1. The method showed good recoveries (100.08 %) and the RSD values for intra- and inter-day precision were 0.78–1.93 and 1.10–2.15%, respectively. The method can be used for quality control assays and in vitro dissolution studies of ELT in tablets.     

荧光材料SrS:Eu,Sm在辐射剂量测量中的应用

采用碳还原法合成了SrS：Eu,Sm,并对光激励发光材料SrS：Eu,Sm的辐射剂量特性进行了研究。将SrS：Eu,Sm材料做成PMMA剂量片在^60Coγ源下接受辐照,然后用自己搭建的在线实时测试系统对剂量片发出的荧光信号进行测量。主要探讨了光激励发光材料SrS：Eu,Sm在辐射剂量测量中的应用。     

酶联免疫吸附分析法测定土壤试样中的阿特拉津

报道一种高灵敏度，高重现性的酶联免疫吸附分析法（ＥＬＩＳＡ）对土壤试样中阿特拉津的测定。测定的线性范围为０．０５￣５．０μｇ／Ｌ，由１４条标准曲线求得的最低检出限在０．０１８￣０．２４μｇ／Ｌ之间，线性相关系数ｒ＝０．９９２２。加标土样分别用含水甲醇和含水乙腈提取的效率都接近１００％，提取液用重蒸水１：２００稀释后可消除基质效应和溶剂效应的影响，加标平均回收率为９９．６％。     

UV-Induced Nucleic Acid–Protein Cross-Linking: Manual on Planning of Irradiation Experiments and Calculation of Absorbed Dose and Quantum Yield

We have developed methods of photochemical quantitation of photobiological studies on UV-induced nucleic acid–protein cross-linking. Cases relating to incoherent low-intensity UV sources, laser UV sources and high-intensity laser UV sources are considered. In the case of low-intensity UV radiation the most important point is the correct determination of absorbed dose. The laser UV pulse energy is easily measured and the short-pulse irradiation also has the advantage of "freezing" the conformation of complexes under study. However, the use of high-intensity laser UV irradiation leads to realizations of two-quantum processes both in nucleic acid chromophores–bases and in solvent–water, which complicates singificantly the processing of results. In this paper methods for calculating the absorbed dose and the quantum yield of cross-linking for all above-mentioned cases are given as well as practical advice.     

土壤pH值测定的不确定度评估

按照NY/T 1377-2007《土壤pH的测定》进行测定,为了评估土壤p H值测定的不确定度,主要研究了测定的重复性、土样质量、水的体积、缓冲溶液和pH计所带来的不确定度,经计算得知,对土壤p H值测定的不确定度影响最大的是水体积和测定的重复性。所以,在测定时可通过使用高精度的量筒以及增加平行试样的次数来降低标准不确定度。     

Al, Ga and In heterometallic wheels and their by-products

Cyclic octanuclear complexes, each containing seven group 13 metals and one d-block metal are reported and preliminary physical characterisation of the compounds discussed.     

Chemical Vapor Deposition of Silicon Dioxide by Direct-Current Corona Discharges in Dry Air Containing Octamethylcyclotetrasiloxane Vapor: Measurement of the Deposition Rate

Experiments in a positive-polarity, wire/plate electrode establish the effects of the concentration of octamethylcyclotetrasiloxane (150–1100 ppm) and the operating current (0.5–2.55 μA/cm length of wire) on the rate of deposition of silicon dioxide on the high voltage wire. The wire is 100 μm radius tungsten and the wire-to-plate spacing is 1.5 cm. Analyses of the deposit with X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy show that it is amorphous silicon dioxide. The deposition rate increases linearly with increasing silicone concentration and corona current. For the concentrations of silicone likely to present in indoor air, the gas-phase processes limit the rate of deposition.     

Preconcentration of Cesium, Cerium, Cobalt, Bismuth, and Lead Radionuclides by Solid-Phase Extraction

A procedure was proposed for the preconcentration of Sr, Cs, Pb, Co, Bi, and Ce beta radionuclides by solid-phase extraction as ion-pair complexes in the system dicyclohexyl-18-crown-6–sodium dodecyl sulfonate.     

Nuclear Reactions and Radionuclides in the Study of Fullerenes

Radiochemical techniques have been applied in various ways to the study of fullerenes and metallofullerenes for the past several years, and they have provided invaluable information pertaining to the stability, structures, and formation of the novel carbon material. This paper reviews those experimental results that have fully shown the usefulness and uniqueness of radionuclides demonstrated in the field of fullerene science.     

含芳醚结构单体及相应高性能聚合物的合成研究状况

全芳香族聚合物兼具优良的耐热性能和突出的力学性能,作为特种工程材料其使用范围不断扩大。由于大量刚性芳环分子单元的紧密堆砌,导致聚合物难溶难熔,成型加工困难,应用受到制约。通过在分子链结构中引入醚键,可以实现对这类聚合物加工性能的有效改进。本文归纳了由双酚类前体采取Williamson亲核取代方法合成不同结构的含醚结构单体(芳香族二元羧酸、二酐、二元胺)研究情况,综述了由这些单体合成的对应含醚芳香族高性能聚合物的研究进展,并提出了在该领域的未来发展方向。     

The ORAC Assay: Mathematical Analysis of the Rate Equations and Some Practical Considerations

ORAC (oxygen radical absorbance capacity), a method widely used for measuring the total antioxidant capacity of biological samples, can also be used for the determination of the relative reactivity of an antioxidant compound (XH) by examining the dependence of the rate of consumption of the probe (PH) on the concentration of XH; initial conditions are chosen in such a way that the rate of consumption of the starting reactants may be assumed to follow a drastically simplified kinetic scheme, and the steady‐state approximation for the concentration of the azo compound peroxyl (ROO^•) radical is invoked to simplify the analysis. Here we first attempted to find an analytical solution to the coupled first‐order ordinary differential equations (ODEs) of the minimal ORAC kinetic system, applying Lie symmetry group theory without any precondition. However, the Lie symmetry transformations applied to the Chini equation, which appeared after mathematical transformations, showed that the form of the coefficients of the Chini equation precluded the analytical solution of the minimal ORAC kinetic system through symmetry reduction. Consequently, an approximate analytical solution was sought, valid for the case when the bimolecular rate constant of XH with ROO^• (i.e., k_x ) was much larger than that of PH with ROO^• (i.e., k_p ). Using numerical solutions of the original set of ODEs of the ORAC kinetic system, the quality of the approximate solution was inspected under conditions that correspond to those employed in several ORAC methods together with a low initial concentration of the azo compound radical initiator. The simulations allowed us to conclude that the approximate analytical solution of the ODEs of the minimal ORAC kinetic system was not entirely devoid of academic interest, but its applicability was restricted to conditions where both k_x ≫ k_p and the initial concentration of XH was higher than that of PH.     

催化发光法同时测定空气中的甲醛、苯和二氧化硫

基于甲醛、苯和二氧化硫在纳米Ti3CeY2O11上的催化发光有交叉敏感现象,在3个波长处分别确定甲醛、苯和二氧化硫浓度与催化发光信号强度的响应关系,再依据发光信号强度的叠加性特征即可获取甲醛、苯和二氧化硫的准确浓度,据此建立了同时测定空气中甲醛、苯和二氧化硫的新方法.3个分析波长分别为420、535和680 nm,敏感材料表面温度为280℃,载气流速为130 mL/min.本方法对甲醛、苯和二氧化硫的检出限(3σ)分别为0.04、0.05和0.10 mg/m3,线性范围分别为0.08~75.60 mg/m3、0.10~101.40 mg/m3和0.30~115.00 mg/m3, 回收率分别为96.4%~103.7%、97.8%~102.5%和97.2%~103.3%.常见共存物,如乙醛、甲苯、硫化氢、氨、甲醇、乙醇和二氧化碳等不干扰测定.连续200 h通浓度均为50 mg/m3的甲醛、苯和二氧化硫混合气体,发光强度的相对偏差≤2%,表明此纳米级复合氧化物对甲醛、苯和二氧化硫的敏感性的寿命长.本方法充分利用了交叉敏感现象,可以实现空气中甲醛、苯和二氧化硫的在线分析.