Equilibrium on line method (ELM) for imposition of Neumann boundary conditions in the finite point method (FPM)

Equilibrium on line method (ELM) for imposition of Neumann boundary conditions in the finite point method (FPM) is presented. In contrary to weak‐form‐based methods, strong‐form‐based methods such as the FPM are often unstable and less accurate, especially for problems governed by partial differential equations with Neumann (derivative) boundary conditions. In this paper, a truly meshless approach for imposition of Neumann boundary conditions in the FPM is proposed and adopted for 2D elasticity analyses. In the proposed method, equilibrium on lines on the Neumann boundary conditions is satisfied as Neumann boundary condition equations. Numerical studies show that this method for imposition of Neumann boundary is simple to implement and computationally efficient and also leads to more stable and accurate results. Copyright © 2006 John Wiley & Sons, Ltd.     

Microdosemeter instrument (MIDN) for assessing risk in space

Radiation in space generally produces higher dose rates than that on the Earth's surface, and contributions from primary galactic and solar events increase with altitude within the magnetosphere. Presently, no personnel monitor is available to astronauts for real-time monitoring of dose, radiation quality and regulatory risk. This group is developing a prototypic instrument for use in an unknown, time-varying radiation field. This microdosemeter-dosemeter nucleon instrument is for use in a spacesuit, spacecraft, remote rover and other applications. It provides absorbed dose, dose rate and dose equivalent in real time so that action can be taken to reduce exposure. Such a system has applications in health physics, anti-terrorism and radiation-hardening of electronics as well. The space system is described and results of ground-based studies are presented and compared with predictions of transport codes. An early prototype in 2007 was successfully launched, the only solid-state microdosemeter to have flown in space.     

荧光法同时测定环境水中的As(Ⅲ)和As(Ⅴ)

研究了一种快速、灵敏的同时测定水中的As(Ⅲ)和As(Ⅴ)的荧光新方法。在pH=6．5～7．5的缓冲介质中，利用2’，7’-二氯荧光素(DCF)作为荧光试剂，激发波长λex=510nm，发射波长λem=528nm下，As(Ⅲ)和DCF竞争碘，引起荧光强度的增强，从而测定痕量As(Ⅲ)。同时利用L-半胱氨酸还原剂将水中的As(Ⅴ)还原成As(Ⅲ)，从而测定As(Ⅲ)和As(Ⅴ)的总量，差减间接测定As(Ⅴ)。As(Ⅲ)浓度在4～180ng／mL范围内，相对荧光强度差值与As(Ⅲ)浓度呈线性关系，线性方程△F=7．82C 0．76，相关系数为0．9991，本法快速、简便、灵敏度高，已用于检测自来水和池塘水中痕量的As(Ⅲ)和As(Ⅴ)，回收率在96％～105％，结果令人满意。     

荧光法同时测定环境水中的As(Ⅲ)和As(V)

研究了一种快速、灵敏的同时测定水中的As(Ⅲ)和As(V)的荧光新方法。在pH=6.5~7.5的缓冲介质中,利用2’,7’-二氯荧光素(DCF)作为荧光试剂,激发波长λex=510nm,发射波长λem=528nm下,As(Ⅲ)和DCF竞争碘,引起荧光强度的增强,从而测定痕量As(Ⅲ)。同时利用L一半胱氨酸还原剂将水中的As(V)还原成As(Ⅲ),从而测定As(Ⅲ)和As(v)的总量,差减间接测定As(V)。As(Ⅲ)浓度在4~180ng/mL范围内,相对荧光强度差值与As(Ⅲ)浓度呈线性关系,线性方程△F=7.82C+0.76,相关系数为o.9991,本法快速、简便、灵敏度高,已用于检测自来水和池塘水中痕量的As(Ⅲ)和As(V),回收率在96%~105%,结果令人满意。     

Genetic polymorphisms and the risk of progressive renal failure in elderly Hungarian patients

The relationship between renal disease progression and genetic polymorphism of enzymes influencing endothelial function remains incompletely understood. We genotyped three cohorts of elderly Hungarian patients: 245 patients with end‐stage renal disease (ESRD) on chronic hemodialysis (HD), 88 patients with mild chronic kidney disease (CKD), and 200 healthy controls. The underlying diagnoses of renal diseases were primary glomerulonephritis, interstitial nephritis, hypertension, diabetic nephropathy, and hereditary diseases. We examined genetic polymorphisms of eight candidate genes associated with endothelial function: endothelial constitutive nitric oxide synthase (ecNOS) T‐786C, endothelin‐1 G5727T, methylenetetrahydrofolate reductase (MTHFR) C677T, paraoxonase‐1 Q192R and M55L, angiotensinogen M235T, angiotensin‐converting enzyme (ACE) I/D and angiotensin II type 1 receptor A1166C gene. Six gene polymorphisms were detected by real‐time polymerase chain reaction with melting‐point analysis, and two via allele‐specific amplification and gel electrophoresis. Control group patients were in Hardy‐Weinberg equilibrium for all tested genotypes. In ESRD patients attributed to hypertension, the endothelin gene G5727T GG genotype occurred significantly less but GT genotype more frequently (P < 0.01 for both). In ESRD patients attributed to primary glomerulonephritis, more ACE DD and less ID genotypes were found (P < 0.02 for both) than in the controls. The underlying diagnosis may modify the association of genetic polymorphism and dialysis‐dependent ESRD.     

Application of the Rietveld method to assess chromium(VI) speciation in chromite ore processing residue

The Rietveld method allows the quantification of crystalline phases and amorphous material identified by X-ray powder diffraction (XRPD) and other diffraction methods. The method assists in determining the speciation of contaminants in solid matrices both qualitatively and quantitatively in a statistically defensible approach, as it does not focus on a microscale. Rietveld was applied to chromite ore processing residue (COPR), a cementitious waste containing hexavalent chromium. Calcium aluminum chromium oxide hydrates (CACs) were the crystalline phases identified by XRPD that bind Cr(6+) in COPR according to their chemical formula. Rietveld quantification, combined with mass balances on Cr(6+), showed that CACs may bind Cr(6+) in variable percentages, ranging from 25% to 85%. Analysis of duplicate samples showed that material variability is the predominant factor of uncertainty in evaluating the role of CACs in Cr(6+) speciation, provided that a consistent quantification strategy is pursued. The choice of strategy was performed on the basis of the pertinent literature, preliminary analyses of the equipment and the software settings, and mass balances. The correlation between the average CAC-bound Cr(6+) concentration and the total Cr(6+) for five samples (R(2)=0.94), extracted from different zones and soil borings, suggests that CACs are a primary sink for Cr(6+) in COPR.     

Immobilization of malarial (Plasmodium falciparum) dihydrofolate reductase for the selection of tight-binding inhibitors from combinatorial library

A simple procedure for selection of tight-binding inhibitors of mutant dihydrofolate reductases from Plasmodium falciparum (PfDHFRs) based on preferential binding to the enzyme immobilized on a Sepharose column has been described. PfDHFRs with a cysteine residue at the C-terminal have been prepared in order to immobilize to a thiopropyl-Sepharose gel via S-S linkage. The amount of immobilized DHFRs was estimated to be 4-5 mg/g of dried gel, and the activities of bound DHFRs were comparable to that of free enzymes. The prepared immobilized enzyme has been used for the selection of tight-binding inhibitors from combinatorial libraries, based on the affinities of each ligand with the enzyme. Free ligands were then identified and analyzed quantitatively by high-performance liquid chromatography-mass spectrometry, and the components with high binding affinity of the library could thus be realized. Results could be confirmed by quantitative analysis of the bound ligands released from the enzyme by guanidine hydrochloride treatment.     

Use of the most likely failure point method for risk estimation and risk uncertainty analysis

The most likely failure point (MLFP) method, developed within the field of structural reliability analysis (where it is known as the FORM/SORM method) is a technique for estimating the risk (probability) that a calculated quantity Q exceeds a set limit Q(lim) when some or all of the inputs to the calculation are uncertain.It can be used as an efficient stand-alone method for this type of risk calculation. However, for application within the field of toxic hazards, it is proposed as a means for performing sensitivity analyses, possibly in parallel with a risk calculation carried out by conventional methods.The basis of the method is outlined and its use is demonstrated by means of an example calculation of the risk arising from an installation containing chlorine. The calculation uses, as a consequence model, commercial software for the prediction of dense gas transport. The risk estimate is shown to be acceptably close to that obtained by the Monte Carlo method. The use of a proposed screening procedure utilising the sensitivity formulas that the method provides, in order to identify the most significant uncertainties, is demonstrated.The identification of a single set of input values containing sufficient information to summarise (at least approximately) the entire risk analysis is considered to be an important feature of the method and is proposed as the basis of a means for assessing the validity of the consequence model.     

Application of new fuzzy-weighted average (NFWA) method to engineering design evaluation

Engineering design evaluation is characterized by imprecise (vague) importance and satisfaction levels of criteria, which are better treated as fuzzy variables rather than as subjective crisp variables. Nevertheless, operations on fuzzy numbers tend to increase unnecessarily the imprecision when they are combined for some applications, particularly, when a fuzzy-weighted average (FWA) is calculated. This paper proposes a novel method of operating on fuzzy numbers to obtain a fuzzy-weighted average of desirability levels during design evaluation. The method produces overall desirability levels less imprecise and more realistic than those of the conventional FWA. Furthermore, the balance points of these fuzzy numbers seem to be more credible than those of the FWA. An example is presented, which demonstrates the advantages of the method developed.     

A method for risk modeling of interdependencies in critical infrastructures

Failures in critical infrastructures may be hazardous to population, economy, and national security. There can be strong interdependencies between various infrastructures, but these interdependencies are seldom accounted for in current risk and vulnerability analyses. To reduce probability and mitigate consequences of infrastructure failures, these interdependencies have to be assessed. The objective of this paper is to present a method for assessing interdependencies of critical infrastructures, as part of a cross-sector risk and vulnerability analysis. The method is based on a relatively simple approach applicable for practitioners, but may be extended for more detailed analyses by specialists. Examples from a case study with the Emergency Preparedness Group of the city of Oslo, Norway, are included.     

Application of the crack compliance method to long axial cracks in pipes with allowance for geometrical nonlinearity and shape imperfections (dents)

Application of the crack compliance method to the analysis of thin-walled rings with a radial crack has two features: a crack is considered as a concentrated angular compliance and the deformation of all other sections of the rings is calculated as for a curvilinear beam. The latter can be most conveniently found by the method of initial parameters where the values of generalized forces and displacements at the end of some zone are determined as a linear combination of their values at the beginning of the zone. The goal of the study is to derive and apply the method of initial parameters equations taking into account the influence of circumferential stresses on the ring curvature. As far as the authors know, this is the first time that the stress intensity factor has been derived for an elastic thin-walled pipe with a radial crack in a geometrically nonlinear formulation. Here, an increase in pressure leads to a somewhat slowed increase in the stress intensity factor. In addition, a number of problems for dents are considered. The effect of the dent shape on the stress-strain state is analyzed. An expression for the stress intensity factor for a complex defect, a crack emanating from the dent apex, is presented.     

Sorption-catalytic method for the determination of copper (II) in combination with planar chromatography

An activating action of hexamethylenediamine is revealed in the copper (II)-catalyzed indicator reaction of iron (III) reduced by sodium thiosulfate. It is shown that the addition of hexamethylenediamine to a mobile phase (thin-layer chromatography) and the impregnation of paper with hexamethylenediamine (paper chromatography) enhance the efficiency of metal separation for the model mixture containing Cu (II), Hg (II), Cd (II), and Pb (II). The techniques for the sorption-catalytic determination of copper (II) with the help of Sorbfil plates, including those in combination with thin-layer chromatography, are developed; they work within the concentration range from 0.005 to 10 ??g/mL, the detection limit being 4 ng/mL, which is approximately an order of magnitude lower than in solution. The methods are tested in analysis of waste and river waters.     

Application of polyaniline for the reduction of toxic Cr(VI) in water

Various oxidation states of polyaniline, as film and powder, were used for reduction of highly toxic Cr(VI) to less toxic Cr(III) ion. The effects of various parameters such as synthesis method, physical and oxidation state of polyaniline, film thickness, solution pH and initial Cr(VI) concentration on the kinetics and efficiency of reduction process were investigated. Results showed that a very broad concentration range of Cr(VI) solutions (10-10(5)ppb by emeraldine base and 10-10(6.5)ppb by leucoemeraldine) can be efficiently (>98%) reduced by polyaniline as film or powder. Cr(VI) solutions with concentrations higher than these ranges were caused to the overoxidation and degradation of polymer. Decreasing of solution pH, increased the kinetics and performance of reduction process, but lowered the Cr(VI) concentration ranges caused the overoxidation and degradation of the polymer. Higher reduction efficiencies were obtained for thicker electrochemically synthesized polyaniline films and for thinner chemically prepared polyaniline free standing films. The ability or capacity of various forms of polyaniline in Cr(VI) reduction was evaluated as the milligrams of Cr(VI) reduced by one gram of various forms of polyaniline.     

A new fictitious time for the dynamic relaxation (DXDR) method

This paper addresses the development of the DXDR method by introducing a modified fictitious time (MFT) increment. The MFT is determined by minimizing the residual force after each iteration. The rank of the convergence rate shows the advantage of the new method. The results obtained from plate and truss analyses demonstrate the potential of the new method. It is shown that, compared with a unit fictitious time, the MFT is more efficient, especially during the initial iterations. Moreover, MFT does not impose any additional constraints on the DXDR method. Copyright © 2007 John Wiley & Sons, Ltd.     

A method for synthesizing the core (Ag)/shell (PSt) composite nanoparticles

Core-shell composite materials have been widely used in many fields. In this paper, the core (Ag)-shell (PSt) composite nanoparticles have been successfully fabricated in microemulsions at ambient pressure. Firstly, Ag nanoparticles with about 60-100 nm in diameters were synthesized by reducing silver nitrate by ascorbic acid, and then, styrene polymerized at the surface of Ag nanoparticles by K₂S₂O₄ initiator in microemulsion solutions. The Ag/PSt core-shell composite nanoparticles were identified by transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and infrared spectra (IR). Results show that Ag-core nanoparticles were coated with ultra thin PSt shell with thickness of about 3-6 nm.     

A new method for assessing the risk of accident associated with darkness

This paper presents a new method for assessing the risk of accidents associated with darkness. The method estimates the risk of accident associated with darkness in terms of an odds ratio, which is defined as follows: [(number of accidents in darkness in a given hour of the day)/(number of accidents in daylight in the same hour of the day)]/[(Number of accidents in a given comparison hour when the case hour is dark)/(Number of accidents in a given comparison hour when the case hour is in daylight)]. This estimate of the risk of accident associated with darkness does not require data on exposure, but relies on the count of accidents in the same pair of hours throughout the year. One of the hours is dark part of the year, but has daylight the rest of the year. The comparison hour, which has daylight the whole year, is used to control for seasonal variations. The aim of relying on the same pair of hours throughout the year is to minimise the influence of potentially confounding factors. Estimates of the risk of injury accidents associated with darkness are developed on the basis of accident data for Norway, Sweden and the Netherlands. It is found that the risk of an injury accident increases by nearly 30% in darkness in urban areas, by nearly 50% in rural areas, and by about 40% for urban and rural areas combined (adjusted estimate).     

Application of the risk oriented accident analysis methodology (ROAAM) to severe accident management in the AP600 advanced light water reactor

An important part of the AP600 design, as well as of the design certification review by the US Nuclear Regulatory Commission, is devoted to ensuring defense in depth through deep consideration and management of severe accidents. Going beyond the traditional Level 2 PRA, in this article we show how this defense in depth was achieved and demonstrated in a consistent manner between prevention and mitigation, through application of the Integrated ROAAM approach. This requires the up-front integration of probabilistic and deterministic thought, which leads naturally to clear and coherent safety goals as an overall guide toward closure.