SYNTH-C, Steady-State and Time-Dependent 3-D Neutron Diffusion with Thermohydraulic Feedback

Energy Technology Data Exchange (ETDEWEB)

Brega, E [ENEL-CRTN, Bastioni di Porta Volta 10, Milan (Italy); Salina, E [A.R.S. Spa, Viale Maino 35, Milan (Italy)

1980-04-01

1 - Description of problem or function: SYNTH-C-STEADY and SYNTH-C- TRANS solve respectively the steady-state and time-dependent few- group neutron diffusion equations in three dimensions x,y,z in the presence of fuel temperature and thermal-hydraulic feedback. The neutron diffusion and delayed precursor equations are approximated by a space-time (z,t) synthesis method with axially discontinuous trial functions. Three thermal-hydraulic and fuel heat transfer models are available viz. COBRA-3C/MIT model, lumped parameter (WIGL) model and adiabatic fuel heat-up model. 2 - Method of solution: The steady-state and time-dependent synthesis equations are solved respectively by the Wielandt's power method and by the theta-difference method (in time), both coupled with a block factorization technique and double precision arithmetic. The thermal-hydraulic model equations are solved by fully implicit finite differences (WIGL) or explicit-implicit difference techniques with iterations (COBRA-EC/MIT). 3 - Restrictions on the complexity of the problem: Except for the few- group limitation, the programs have no other fixed limitation so the ability to run a problem depends only on the available computer storage.

Solution of the neutron diffusion equation to study the 3D distribution of power, applied to nuclear reactors

International Nuclear Information System (INIS)

Costa, Danilo Leite

2013-01-01

This work aims to present a study about the power distribution behavior in a PWR type reactor, considering both intensity and migration of power peaks due to insertion of control rods into the core. Employing the multidimensional steady-state neutron diffusion equation in order to simulate the neutron flux, and using the Finite Difference Method. Furthermore, based on the axial power distribution on the largest heat flux rod, is carried out thermal analysis of this rod and associated coolant channel. For this purpose is employed the FueLRod 3 D code, it uses the Finite Element Method to model the fuel rod and the associated coolant channel, allowing the thermohydraulics simulation of a single rod discretized in three dimensions, considering the heat flux from the pellet, crossing the gap and the cladding until it reaches the coolant. (author)

Note: Coincidence measurements of 3He and neutrons from a compact D-D neutron generator

Science.gov (United States)

Ji, Q.; Lin, C.-J.; Tindall, C.; Garcia-Sciveres, M.; Schenkel, T.; Ludewigt, B. A.

2017-05-01

Tagging of neutrons (2.45 MeV) with their associated 3He particles from deuterium-deuterium (D-D) fusion reactions has been demonstrated in a compact neutron generator setup enabled by a high brightness, microwave-driven ion source with a high fraction of deuterons. Energy spectra with well separated peaks of the D-D fusion reaction products, 3He, tritons, and protons, were measured with a silicon PIN diode. The neutrons were detected using a liquid scintillator detector with pulse shape discrimination. By correlating the 3He detection events with the neutron detection in time, we demonstrated the tagging of emitted neutrons with 3He particles detected with a Si PIN diode detector mounted inside the neutron generator vacuum vessel.

HEXAB-3D, 3-D Few-Group Diffusion for Hexagonal Core Geometry

International Nuclear Information System (INIS)

Apostolov, T.G.; Ivanov, K.N.; Manolova, M.A.

2002-01-01

1 - Description of program or function: A three-dimensional few-group calculational model based on diffusion theory has been developed for calculating the basic neutron physical characteristics of power reactors which have a hexagonal core configuration with a heterogeneous region structure in axial direction. There are two versions of the model: - HEXAB-III-30 - the solution range in horizontal plane is 30 - sector of reactor core - HEXAB-III-360 - the solution range in horizontal plane is full core. 2 - Method of solution: In the HEXAB-3D code the nine-point mesh-centered finite-difference approximation of neutron diffusion equation is applied. The standard inner-outer iterative strategy is used. Inner iterations are solved using two different incomplete factorization techniques: AGA two-sweep iterative method and modified AGA two-sweep iterative method both accelerated by the double successive over-relaxation procedure. The power method, combined with two- or three-term Chebishev polynomial acceleration for outer iterations is applied in the code. To improve the accuracy of the calculated integral and local reactor parameters without significantly increasing computer time and storage an effective approach has been developed. It decreases errors due to the use of coarse mesh by means of correcting the coefficients of finite- difference scheme. 3 - Restrictions on the complexity of the problem: Maximum of 10 energy groups, 30 horizontal layers and 100 material compositions

3-D neutron transport benchmarks

International Nuclear Information System (INIS)

Takeda, T.; Ikeda, H.

1991-03-01

A set of 3-D neutron transport benchmark problems proposed by the Osaka University to NEACRP in 1988 has been calculated by many participants and the corresponding results are summarized in this report. The results of K eff , control rod worth and region-averaged fluxes for the four proposed core models, calculated by using various 3-D transport codes are compared and discussed. The calculational methods used were: Monte Carlo, Discrete Ordinates (Sn), Spherical Harmonics (Pn), Nodal Transport and others. The solutions of the four core models are quite useful as benchmarks for checking the validity of 3-D neutron transport codes

An Angiotensin I-Converting Enzyme Mutation (Y465D) Causes a Dramatic Increase in Blood ACE via Accelerated ACE Shedding

Science.gov (United States)

Gordon, Kerry; Nesterovitch, Andrew B.; Lünsdorf, Heinrich; Chen, Zhenlong; Castellon, Maricela; Popova, Isolda A.; Kalinin, Sergey; Mendonca, Emma; Petukhov, Pavel A.; Schwartz, David E.

2011-01-01

Background Angiotensin I-converting enzyme (ACE) metabolizes a range of peptidic substrates and plays a key role in blood pressure regulation and vascular remodeling. Thus, elevated ACE levels may be associated with an increased risk for different cardiovascular or respiratory diseases. Previously, a striking familial elevation in blood ACE was explained by mutations in the ACE juxtamembrane region that enhanced the cleavage-secretion process. Recently, we found a family whose affected members had a 6-fold increase in blood ACE and a Tyr465Asp (Y465D) substitution, distal to the stalk region, in the N domain of ACE. Methodology/Principal Findings HEK and CHO cells expressing mutant (Tyr465Asp) ACE demonstrate a 3- and 8-fold increase, respectively, in the rate of ACE shedding compared to wild-type ACE. Conformational fingerprinting of mutant ACE demonstrated dramatic changes in ACE conformation in several different epitopes of ACE. Cell ELISA carried out on CHO-ACE cells also demonstrated significant changes in local ACE conformation, particularly proximal to the stalk region. However, the cleavage site of the mutant ACE - between Arg1203 and Ser1204 - was the same as that of WT ACE. The Y465D substitution is localized in the interface of the N-domain dimer (from the crystal structure) and abolishes a hydrogen bond between Tyr465 in one monomer and Asp462 in another. Conclusions/Significance The Y465D substitution results in dramatic increase in the rate of ACE shedding and is associated with significant local conformational changes in ACE. These changes could result in increased ACE dimerization and accessibility of the stalk region or the entire sACE, thus increasing the rate of cleavage by the putative ACE secretase (sheddase). PMID:21998728

An angiotensin I-converting enzyme mutation (Y465D causes a dramatic increase in blood ACE via accelerated ACE shedding.

Directory of Open Access Journals (Sweden)

Sergei M Danilov

Full Text Available Angiotensin I-converting enzyme (ACE metabolizes a range of peptidic substrates and plays a key role in blood pressure regulation and vascular remodeling. Thus, elevated ACE levels may be associated with an increased risk for different cardiovascular or respiratory diseases. Previously, a striking familial elevation in blood ACE was explained by mutations in the ACE juxtamembrane region that enhanced the cleavage-secretion process. Recently, we found a family whose affected members had a 6-fold increase in blood ACE and a Tyr465Asp (Y465D substitution, distal to the stalk region, in the N domain of ACE.HEK and CHO cells expressing mutant (Tyr465Asp ACE demonstrate a 3- and 8-fold increase, respectively, in the rate of ACE shedding compared to wild-type ACE. Conformational fingerprinting of mutant ACE demonstrated dramatic changes in ACE conformation in several different epitopes of ACE. Cell ELISA carried out on CHO-ACE cells also demonstrated significant changes in local ACE conformation, particularly proximal to the stalk region. However, the cleavage site of the mutant ACE--between Arg1203 and Ser1204--was the same as that of WT ACE. The Y465D substitution is localized in the interface of the N-domain dimer (from the crystal structure and abolishes a hydrogen bond between Tyr465 in one monomer and Asp462 in another.The Y465D substitution results in dramatic increase in the rate of ACE shedding and is associated with significant local conformational changes in ACE. These changes could result in increased ACE dimerization and accessibility of the stalk region or the entire sACE, thus increasing the rate of cleavage by the putative ACE secretase (sheddase.

ACE insertion/deletion (I/D) polymorphism and diabetic nephropathy.

Science.gov (United States)

Rahimi, Zohreh

2012-10-01

Angiotensin converting enzyme (ACE) gene encodes ACE, a key component of renin angiotensin system (RAS), plays an important role in blood pressure homeostasis by generating the vasoconstrictor peptide angiotensin II. Directory of Open Access Journals (DOAJ), Google Scholar, Pubmed (NLM), LISTA (EBSCO) and Web of Science have been searched. The presence of ACE insertion/deletion (I/D) polymorphism affects the plasma level of ACE. ACE DD genotype is associated with the highest systemic and renal ACE levels compared with the lowest ACE activity in carriers of II genotype. In this review focus has been performed on the study of ACE I/D polymorphism in various populations and its influence on the risk of onset and progression of diabetic nephropathy. Also, association between ACE I/D polymorphism and response to ACE inhibitor and angiotensin II receptor antagonists will be reviewed. Further, synergistic effect of this polymorphism and variants of some genes on the risk of development of diabetic nephropathy will be discussed.

Synergism of the method of characteristic, R-functions and diffusion solution for accurate representation of 3D neutron interactions in research reactors using the AGENT code system

International Nuclear Information System (INIS)

Hursin, Mathieu; Xiao Shanjie; Jevremovic, Tatjana

2006-01-01

This paper summarizes the theoretical and numerical aspects of the AGENT code methodology accurately applied for detailed three-dimensional (3D) multigroup steady-state modeling of neutron interactions in complex heterogeneous reactor domains. For the first time we show the fine-mesh neutron scalar flux distribution in Purdue research reactor (that was built over forty years ago). The AGENT methodology is based on the unique combination of the three theories: the method of characteristics (MOC) used to simulate the neutron transport in two-dimensional (2D) whole core heterogeneous calculation, the theory of R-functions used as a mathematical tool to describe the true geometry and fuse with the MOC equations, and one-dimensional (1D) higher-order diffusion correction of 2D transport model to account for full 3D heterogeneous whole core representation. The synergism between the radial 2D transport and the 1D axial transport (to take into account the axial neutron interactions and leakage), called the 2D/1D method (used in DeCART and CHAPLET codes), provides a 3D computational solution. The unique synergism between the AGENT geometrical algorithm capable of modeling any current or future reactor core geometry and 3D neutron transport methodology is described in details. The 3D AGENT accuracy and its efficiency are demonstrated showing the eigenvalues, point-wise flux and reaction rate distributions in representative reactor geometries. The AGENT code, comprising this synergism, represents a building block of the computational system, called the virtual reactor. Its main purpose is to perform 'virtual' experiments and demonstrations of various mainly university research reactor experiments

Neutron transport in hexagonal reactor cores modeled by trigonal-geometry diffusion and simplified P{sub 3} nodal methods

Energy Technology Data Exchange (ETDEWEB)

Duerigen, Susan

2013-05-15

The superior advantage of a nodal method for reactor cores with hexagonal fuel assemblies discretized as cells consisting of equilateral triangles is its mesh refinement capability. In this thesis, a diffusion and a simplified P{sub 3} (or SP{sub 3}) neutron transport nodal method are developed based on trigonal geometry. Both models are implemented in the reactor dynamics code DYN3D. As yet, no other well-established nodal core analysis code comprises an SP{sub 3} transport theory model based on trigonal meshes. The development of two methods based on different neutron transport approximations but using identical underlying spatial trigonal discretization allows a profound comparative analysis of both methods with regard to their mathematical derivations, nodal expansion approaches, solution procedures, and their physical performance. The developed nodal approaches can be regarded as a hybrid NEM/AFEN form. They are based on the transverse-integration procedure, which renders them computationally efficient, and they use a combination of polynomial and exponential functions to represent the neutron flux moments of the SP{sub 3} and diffusion equations, which guarantees high accuracy. The SP{sub 3} equations are derived in within-group form thus being of diffusion type. On this basis, the conventional diffusion solver structure can be retained also for the solution of the SP{sub 3} transport problem. The verification analysis provides proof of the methodological reliability of both trigonal DYN3D models. By means of diverse hexagonal academic benchmark and realistic detailed-geometry full-transport-theory problems, the superiority of the SP{sub 3} transport over the diffusion model is demonstrated in cases with pronounced anisotropy effects, which is, e.g., highly relevant to the modeling of fuel assemblies comprising absorber material.

Parareal in time 3D numerical solver for the LWR Benchmark neutron diffusion transient model

Energy Technology Data Exchange (ETDEWEB)

Baudron, Anne-Marie, E-mail: anne-marie.baudron@cea.fr [Laboratoire de Recherche Conventionné MANON, CEA/DEN/DANS/DM2S and UPMC-CNRS/LJLL (France); CEA-DRN/DMT/SERMA, CEN-Saclay, 91191 Gif sur Yvette Cedex (France); Lautard, Jean-Jacques, E-mail: jean-jacques.lautard@cea.fr [Laboratoire de Recherche Conventionné MANON, CEA/DEN/DANS/DM2S and UPMC-CNRS/LJLL (France); CEA-DRN/DMT/SERMA, CEN-Saclay, 91191 Gif sur Yvette Cedex (France); Maday, Yvon, E-mail: maday@ann.jussieu.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7598, Laboratoire Jacques-Louis Lions and Institut Universitaire de France, F-75005, Paris (France); Laboratoire de Recherche Conventionné MANON, CEA/DEN/DANS/DM2S and UPMC-CNRS/LJLL (France); Brown Univ, Division of Applied Maths, Providence, RI (United States); Riahi, Mohamed Kamel, E-mail: riahi@cmap.polytechnique.fr [Laboratoire de Recherche Conventionné MANON, CEA/DEN/DANS/DM2S and UPMC-CNRS/LJLL (France); CMAP, Inria-Saclay and X-Ecole Polytechnique, Route de Saclay, 91128 Palaiseau Cedex (France); Salomon, Julien, E-mail: salomon@ceremade.dauphine.fr [CEREMADE, Univ Paris-Dauphine, Pl. du Mal. de Lattre de Tassigny, F-75016, Paris (France)

2014-12-15

In this paper we present a time-parallel algorithm for the 3D neutrons calculation of a transient model in a nuclear reactor core. The neutrons calculation consists in numerically solving the time dependent diffusion approximation equation, which is a simplified transport equation. The numerical resolution is done with finite elements method based on a tetrahedral meshing of the computational domain, representing the reactor core, and time discretization is achieved using a θ-scheme. The transient model presents moving control rods during the time of the reaction. Therefore, cross-sections (piecewise constants) are taken into account by interpolations with respect to the velocity of the control rods. The parallelism across the time is achieved by an adequate use of the parareal in time algorithm to the handled problem. This parallel method is a predictor corrector scheme that iteratively combines the use of two kinds of numerical propagators, one coarse and one fine. Our method is made efficient by means of a coarse solver defined with large time step and fixed position control rods model, while the fine propagator is assumed to be a high order numerical approximation of the full model. The parallel implementation of our method provides a good scalability of the algorithm. Numerical results show the efficiency of the parareal method on large light water reactor transient model corresponding to the Langenbuch–Maurer–Werner benchmark.

ACTN3 R577X and ACE I/D gene variants influence performance in elite sprinters: a multi-cohort study.

Science.gov (United States)

Papadimitriou, Ioannis D; Lucia, Alejandro; Pitsiladis, Yannis P; Pushkarev, Vladimir P; Dyatlov, Dmitry A; Orekhov, Evgeniy F; Artioli, Guilherme G; Guilherme, João Paulo L F; Lancha, Antonio H; Ginevičienė, Valentina; Cieszczyk, Pawel; Maciejewska-Karlowska, Agnieszka; Sawczuk, Marek; Muniesa, Carlos A; Kouvatsi, Anastasia; Massidda, Myosotis; Calò, Carla Maria; Garton, Fleur; Houweling, Peter J; Wang, Guan; Austin, Krista; Druzhevskaya, Anastasiya M; Astratenkova, Irina V; Ahmetov, Ildus I; Bishop, David J; North, Kathryn N; Eynon, Nir

2016-04-13

To date, studies investigating the association between ACTN3 R577X and ACE I/D gene variants and elite sprint/power performance have been limited by small cohorts from mixed sport disciplines, without quantitative measures of performance. To examine the association between these variants and sprint time in elite athletes. We collected a total of 555 best personal 100-, 200-, and 400-m times of 346 elite sprinters in a large cohort of elite Caucasian or African origin sprinters from 10 different countries. Sprinters were genotyped for ACTN3 R577X and ACE ID variants. On average, male Caucasian sprinters with the ACTN3 577RR or the ACE DD genotype had faster best 200-m sprint time than their 577XX (21.19 ± 0.53 s vs. 21.86 ± 0.54 s, p = 0.016) and ACE II (21.33 ± 0.56 vs. 21.93 ± 0.67 sec, p = 0.004) counterparts and only one case of ACE II, and no cases of ACTN3 577XX, had a faster 200-m time than the 2012 London Olympics qualifying (vs. 12 qualified sprinters with 577RR or 577RX genotype). Caucasian sprinters with the ACE DD genotype had faster best 400-m sprint time than their ACE II counterparts (46.94 ± 1.19 s vs. 48.50 ± 1.07 s, p = 0.003). Using genetic models we found that the ACTN3 577R allele and ACE D allele dominant model account for 0.92 % and 1.48 % of sprint time variance, respectively. Despite sprint performance relying on many gene variants and environment, the % sprint time variance explained by ACE and ACTN3 is substantial at the elite level and might be the difference between a world record and only making the final.

Comparison of 2D and 3D Neutron Transport Analyses on Yonggwang Unit 3 Reactor

International Nuclear Information System (INIS)

Maeng, Aoung Jae; Kim, Byoung Chul; Lim, Mi Joung; Kim, Kyung Sik; Jeon, Young Kyou; Yoo, Choon Sung

2012-01-01

10 CFR Part 50 Appendix H requires periodical surveillance program in the reactor vessel (RV) belt line region of light water nuclear power plant to check vessel integrity resulting from the exposure to neutron irradiation and thermal environment. Exact exposure analysis of the neutron fluence based on right modeling and simulations is the most important in the evaluation. Traditional 2 dimensional (D) and 1D synthesis methodologies have been widely applied to evaluate the fast neutron (E > 1.0 MeV) fluence exposure to RV. However, 2D and 1D methodologies have not provided accurate fast neutron fluence evaluation at elevations far above or below the active core region. RAPTOR-M3G (RApid Parallel Transport Of Radiation - Multiple 3D Geometries) program for 3D geometries calculation was therefore developed both by Westinghouse Electronic Company, USA and Korea Reactor Integrity Surveillance Technology (KRIST) for the analysis of In-Vessel Surveillance Test and Ex-Vessel Neutron Dosimetry (EVND). Especially EVND which is installed at active core height between biological shielding material and concrete also evaluates axial neutron fluence by placing three dosimetries each at Top, Middle and Bottom part of the angle representing maximum neutron fluence. The EVND programs have been applied to the Korea Nuclear Plants. The objective of this study is therefore to compare the 3D and the 2D Neutron Transport Calculations and Analyses on the Yonggwang unit 3 Reactor as an example

Fast diffusion in the intermetallics Ni3Sb and Fe3Si: a neutron scattering study

International Nuclear Information System (INIS)

Randl, O.G.

1994-02-01

We present the results of neutron scattering experiments designed to elucidate the reason for the extraordinarily fast majority component diffusion in two intermetallic alloys of DO 3 structure, Fe 3 Si and Ni 3 Sb: We have performed diffraction measurements in order to determine the crystal structure and the state of order of both alloys as a function of composition and temperature. The results on Fe 3 Si essentially confirm the classical phase diagram: The alloys of a composition between 16 and 25 at % Si are DO 3 -ordered at room temperature and disorder at high temperatures. The high-temperature phase Ni 3 Sb also crystallizes in the DO 3 structure. Vacancies are created in one Ni sublattice at Sb contents beyond 25 at %. In a second step the diffusion mechanism in Ni 3 Sb has been studied by means of quasielastic neutron scattering. The results are reconcileable with a very simple NN jump model between the two different Ni sublattices. Finally, the lattice dynamics of Fe 3 Si and Ni 3 Sb has been studied by inelastic neutron scattering in dependence of temperature (both alloys) and alloy composition (Fe 3 Si only). The results on Fe 3 Si indicate clearly that phonon enhancement is not the main reason for fast diffusion in this alloy. In Ni 3 Sb no typical signs of phonon-enhanced diffusion have been found either. As a conclusion, fast diffusion in DO 3 intermetallics is explained by extraordinarily high vacancy concentrations (several atomic percent) in the majority component sublattices. (author)

Evaluation of ACE gene I/D polymorphism in Iranian elite athletes.

Science.gov (United States)

Shahmoradi, Somayeh; Ahmadalipour, Ali; Salehi, Mansoor

2014-01-01

Angiotensin converting enzyme (ACE) is an important gene, which is associated with the successful physical activity. The ACE gene has a major polymorphism (I/D) in intron 16 that determines its plasma and tissue levels. In this study, we aimed to determine whether there is an association between this polymorphism and sports performance in our studied population including elite athletes of different sports disciplines. We investigated allele frequency and genotype distribution of the ACE gene in 156 Iranian elite athletes compared to 163 healthy individuals. We also investigated this allele frequency between elite athletes in three functional groups of endurance, power, and mixed sports performances. DNA was extracted from peripheral blood, and polymerase chain reaction (PCR) method was performed on intron 16 of the ACE gene. The ACE genotype was determined for each subject. Statistical analysis was performed by SPSS 15, and results were analyzed by Chi-Square test. There was a significant difference in genotype distribution and allele frequency of the ACE gene in athletes and control group (P = 0.05, P = 0.03, respectively). There was also a significant difference in allele frequency of the ACE gene in 3 groups of athletes with different sports disciplines (P = 0.045). Proportion of the ACE gene D allele was greater in elite endurance athletes (37 high-distance cyclists) than two other groups. Findings of the present study demonstrated that there is an association between the ACE gene I/D polymorphism and sports performance in Iranian elite athletes.

ACE I/D genotype, adiposity, and blood pressure in children

Directory of Open Access Journals (Sweden)

Rothschild Max

2009-03-01

Full Text Available Abstract Background Angiotensin converting enzyme (ACE is a possible candidate gene that may influence both body fatness and blood pressure. Although several genetic studies have been conducted in adults, relatively few studies have examined the contribution of potential candidate genes, and specifically ACE I/D, on adiposity and BP phenotypes in childhood. Such studies may prove insightful for the development of the obesity-hypertension phenotype early in life. The purpose of this study was to examine differences in body fatness and resting blood pressure (BP by ACE I/D genotype, and determine if the association between adiposity and BP varies by ACE I/D genotype in children. Methods 152 children (75 girls, 77 boys were assessed for body composition (% body fat using dual energy x-ray absorbtiometry and resting BP according to American Heart Association recommendations. Buccal cell samples were genotyped using newly developed PCR-RFLP tests for two SNPs (rs4341 and rs4343 in complete linkage disequilibrium with the ACE I/D polymorphism. Partial correlations were computed to assess the ociations between % body fat and BP in the total sample and by genotype. ANCOVA was used to examine differences in resting BP by ACE I/D genotype and fatness groups. Results Approximately 39% of youth were overfat based on % body fat (>30% fat in girls, 25% fat in boys. Body mass, body mass index, and fat-free mass were significantly higher in the ACE D-carriers compared to the II group (p Conclusion ACE D-carriers are heavier than ACE II children; however, BP did not differ by ACE I/D genotype but was adversely influenced in the overfat D-carriers. Further studies are warranted to investigate the genetics of fatness and BP phenotypes in children.

Identification and characterisation of the angiotensin converting enzyme-3 (ACE3 gene: a novel mammalian homologue of ACE

Directory of Open Access Journals (Sweden)

Phelan Anne

2007-06-01

Full Text Available Abstract Background Mammalian angiotensin converting enzyme (ACE plays a key role in blood pressure regulation. Although multiple ACE-like proteins exist in non-mammalian organisms, to date only one other ACE homologue, ACE2, has been identified in mammals. Results Here we report the identification and characterisation of the gene encoding a third homologue of ACE, termed ACE3, in several mammalian genomes. The ACE3 gene is located on the same chromosome downstream of the ACE gene. Multiple sequence alignment and molecular modelling have been employed to characterise the predicted ACE3 protein. In mouse, rat, cow and dog, the predicted protein has mutations in some of the critical residues involved in catalysis, including the catalytic Glu in the HEXXH zinc binding motif which is Gln, and ESTs or reverse-transcription PCR indicate that the gene is expressed. In humans, the predicted ACE3 protein has an intact HEXXH motif, but there are other deletions and insertions in the gene and no ESTs have been identified. Conclusion In the genomes of several mammalian species there is a gene that encodes a novel, single domain ACE-like protein, ACE3. In mouse, rat, cow and dog ACE3, the catalytic Glu is replaced by Gln in the putative zinc binding motif, indicating that in these species ACE3 would lack catalytic activity as a zinc metalloprotease. In humans, no evidence was found that the ACE3 gene is expressed and the presence of deletions and insertions in the sequence indicate that ACE3 is a pseudogene.

Pin level neutronic - thermal hydraulic two-way-coupling using DYN3D-SP3 and SUBCHANFLOW

International Nuclear Information System (INIS)

Torres, Armando Gomez; Espinoza, Victor Sanchez; Imke, Uwe; Juan, Rafael Macian

2011-01-01

Nowadays several Reactor Dynamic Codes, (RDC) are able to solve the diffusion equation or even the transport equation (SP3 approximation) considering feedback parameters coming from the thermalhydraulic (TH) core behavior. These kinds of codes (DYN3D, PARCS, among others) usually contain a 1D two phase flow thermalhydraulic model capable to pass them assembly averaged feedback parameters. At fuel assembly base this nodal coupling is completely a two way coupling. The Neutronic part calculates the mean power of the whole assembly and passes it to the TH part in order to actualize the heat source. In turn, the TH model passes the assembly-based feedback parameters to the neutronic code for actualizing the nodal cross sections. The process will be repeated until convergence. At pin level, the current situation is somehow different. Although the neutronic solver can pass the pin power distribution in every sub - node (pin distribution), the 1-D TH model will average the pin power distribution to assembly-based scale and will give back assembly averaged feedbacks to the neutronic part for cross sections up-date (one and a half way coupling), leading to information loss in the calculation. A new coupled program system DYNSUB was developed by coupling DYN3D-SP3 and SUBCHANFLOW at pin level. DYNSUB was used to analyze stationary PWR minicore problems at pin-level. The comparison of the Keff predicted by DYNSUB with the one calculated by DYN3D-SP3 (coarse TH solution) shows small differences of up to 26 pcm. Differences up to 4.5% were found in the radial distribution of the pin power. The local safety parameters such as cladding and fuel temperature predicted with DYNSUB shows larger deviations compared with the ones obtained with DYN3D-SP3. These differences may increase when analyzing transients. (author)

Neutron flux calculations for the Rossendorf research reactor in (hex)- and (hex,z)-geometry using SNAP-3D

International Nuclear Information System (INIS)

Koch, R.; Findeisen, A.

1986-04-01

The multigroup neutron diffusion theory code SNAP-3D has been used to perform time independent neutron flux and power calculations of the 10 MW Rossendorf research reactor of the type WWR-SM. The report describes these calculations, as well as the actual reactor configuration, some details of the code SNAP-3D, and two- and three-dimensional reactor models. For evaluating the calculations some flux values and control rod worths have been compared with those of measurements. (author)

Identification and characterisation of the angiotensin converting enzyme-3 (ACE3) gene: a novel mammalian homologue of ACE

OpenAIRE

Rella, Monika; Elliot, Joann L; Revett, Timothy J; Lanfear, Jerry; Phelan, Anne; Jackson, Richard M; Turner, Anthony J; Hooper, Nigel M

2007-01-01

Abstract Background Mammalian angiotensin converting enzyme (ACE) plays a key role in blood pressure regulation. Although multiple ACE-like proteins exist in non-mammalian organisms, to date only one other ACE homologue, ACE2, has been identified in mammals. Results Here we report the identification and characterisation of the gene encoding a third homologue of ACE, termed ACE3, in several mammalian genomes. The ACE3 gene is located on the same chromosome downstream of the ACE gene. Multiple ...

Solution of the neutron diffusion equation to study the 3D distribution of power, applied to nuclear reactors; Solucao da equacao de difusao de neutrons para o estudo da distribuicao de potencia em 3D, aplicado a reatores nucleares

Energy Technology Data Exchange (ETDEWEB)

Costa, Danilo Leite

2013-07-01

This work aims to present a study about the power distribution behavior in a PWR type reactor, considering both intensity and migration of power peaks due to insertion of control rods into the core. Employing the multidimensional steady-state neutron diffusion equation in order to simulate the neutron flux, and using the Finite Difference Method. Furthermore, based on the axial power distribution on the largest heat flux rod, is carried out thermal analysis of this rod and associated coolant channel. For this purpose is employed the FueLRod{sub 3}D code, it uses the Finite Element Method to model the fuel rod and the associated coolant channel, allowing the thermohydraulics simulation of a single rod discretized in three dimensions, considering the heat flux from the pellet, crossing the gap and the cladding until it reaches the coolant. (author)

Fundamentals of 3-D Neutron Kinetics and Current Status

International Nuclear Information System (INIS)

Aragones, J.M.

2008-01-01

This lecture includes the following topics: 1) A summary of the cell and lattice calculations used to generate the neutron reaction data for neutron kinetics, including the spectral and burnup calculations of LWR cells and fuel assembly lattices, and the main nodal kinetics parameters: mean neutron generation time and delayed neutron fraction; 2) the features of the advanced nodal methods for 3-D LWR core physics, including the treatment of partially inserted control rods, fuel assembly grids, fuel burnup and xenon and samarium transients, and excore detector responses, that are essential for core surveillance, axial offset control and operating transient analysis; 3) the advanced nodal methods for 3-D LWR core neutron kinetics (best estimate safety analysis, real-time simulation); and 4) example applications to 3-D neutron kinetics problems in transient analysis of PWR cores, including model, benchmark and operational transients without, or with simple, thermal-hydraulics feedback.

Estimating anisotropic diffusion of neutrons near the boundary of a pebble bed random system

Energy Technology Data Exchange (ETDEWEB)

Vasques, R. [Department of Mathematics, Center for Computational Engineering Science, RWTH Aachen University, Schinkel Strasse 2, D-52062 Aachen (Germany)

2013-07-01

Due to the arrangement of the pebbles in a Pebble Bed Reactor (PBR) core, if a neutron is located close to a boundary wall, its path length probability distribution function in directions of flight parallel to the wall is significantly different than in other directions. Hence, anisotropic diffusion of neutrons near the boundaries arises. We describe an analysis of neutron transport in a simplified 3-D pebble bed random system, in which we investigate the anisotropic diffusion of neutrons born near one of the system's boundary walls. While this simplified system does not model the actual physical process that takes place near the boundaries of a PBR core, the present work paves the road to a formulation that may enable more accurate diffusion simulations of such problems to be performed in the future. Monte Carlo codes have been developed for (i) deriving realizations of the 3-D random system, and (ii) performing 3-D neutron transport inside the heterogeneous model; numerical results are presented for three different choices of parameters. These numerical results are used to assess the accuracy of estimates for the mean-squared displacement of neutrons obtained with the diffusion approximations of the Atomic Mix Model and of the recently introduced [1] Non-Classical Theory with angular-dependent path length distribution. The Non-Classical Theory makes use of a Generalized Linear Boltzmann Equation in which the locations of the scattering centers in the system are correlated and the distance to collision is not exponentially distributed. We show that the results predicted using the Non-Classical Theory successfully model the anisotropic behavior of the neutrons in the random system, and more closely agree with experiment than the results predicted by the Atomic Mix Model. (authors)

Estimating anisotropic diffusion of neutrons near the boundary of a pebble bed random system

International Nuclear Information System (INIS)

Vasques, R.

2013-01-01

Due to the arrangement of the pebbles in a Pebble Bed Reactor (PBR) core, if a neutron is located close to a boundary wall, its path length probability distribution function in directions of flight parallel to the wall is significantly different than in other directions. Hence, anisotropic diffusion of neutrons near the boundaries arises. We describe an analysis of neutron transport in a simplified 3-D pebble bed random system, in which we investigate the anisotropic diffusion of neutrons born near one of the system's boundary walls. While this simplified system does not model the actual physical process that takes place near the boundaries of a PBR core, the present work paves the road to a formulation that may enable more accurate diffusion simulations of such problems to be performed in the future. Monte Carlo codes have been developed for (i) deriving realizations of the 3-D random system, and (ii) performing 3-D neutron transport inside the heterogeneous model; numerical results are presented for three different choices of parameters. These numerical results are used to assess the accuracy of estimates for the mean-squared displacement of neutrons obtained with the diffusion approximations of the Atomic Mix Model and of the recently introduced [1] Non-Classical Theory with angular-dependent path length distribution. The Non-Classical Theory makes use of a Generalized Linear Boltzmann Equation in which the locations of the scattering centers in the system are correlated and the distance to collision is not exponentially distributed. We show that the results predicted using the Non-Classical Theory successfully model the anisotropic behavior of the neutrons in the random system, and more closely agree with experiment than the results predicted by the Atomic Mix Model. (authors)

Verification of 3-D generation code package for neutronic calculations of WWERs

International Nuclear Information System (INIS)

Sidorenko, V.D.; Aleshin, S.S.; Bolobov, P.A.; Bolshagin, S.N.; Lazarenko, A.P.; Markov, A.V.; Morozov, V.V.; Syslov, A.A.; Tsvetkov, V.M.

2000-01-01

Materials on verification of the 3 -d generation code package for WWERs neutronic calculations are presented. The package includes: - spectral code TVS-M; - 2-D fine mesh diffusion code PERMAK-A for 4- or 6-group calculation of WWER core burnup; - 3-D coarse mesh diffusion code BIPR-7A for 2-group calculations of quasi-stationary WWERs regimes. The materials include both TVS-M verification data and verification data on PERMAK-A and BIPR-7A codes using constant libraries generated with TVS-M. All materials are related to the fuel without Gd. TVS-M verification materials include results of comparison both with benchmark calculations obtained by other codes and with experiments carried out at ZR-6 critical facility. PERMAK-A verification materials contain results of comparison with TVS-M calculations and with ZR-6 experiments. BIPR-7A materials include comparison with operation data for Dukovany-2 and Loviisa-1 NPPs (WWER-440) and for Balakovo NPP Unit 4 (WWER-1000). The verification materials demonstrate rather good accuracy of calculations obtained with the use of code package of the 3 -d generation. (Authors)

SYN3D: a single-channel, spatial flux synthesis code for diffusion theory calculations

Energy Technology Data Exchange (ETDEWEB)

Adams, C. H.

1976-07-01

This report is a user's manual for SYN3D, a computer code which uses single-channel, spatial flux synthesis to calculate approximate solutions to two- and three-dimensional, finite-difference, multigroup neutron diffusion theory equations. SYN3D is designed to run in conjunction with any one of several one- and two-dimensional, finite-difference codes (required to generate the synthesis expansion functions) currently being used in the fast reactor community. The report describes the theory and equations, the use of the code, and the implementation on the IBM 370/195 and CDC 7600 of the version of SYN3D available through the Argonne Code Center.

SYN3D: a single-channel, spatial flux synthesis code for diffusion theory calculations

International Nuclear Information System (INIS)

Adams, C.H.

1976-07-01

This report is a user's manual for SYN3D, a computer code which uses single-channel, spatial flux synthesis to calculate approximate solutions to two- and three-dimensional, finite-difference, multigroup neutron diffusion theory equations. SYN3D is designed to run in conjunction with any one of several one- and two-dimensional, finite-difference codes (required to generate the synthesis expansion functions) currently being used in the fast reactor community. The report describes the theory and equations, the use of the code, and the implementation on the IBM 370/195 and CDC 7600 of the version of SYN3D available through the Argonne Code Center

Transport of D-D fusion neutrons in thick concrete

International Nuclear Information System (INIS)

Ku, L.P.; Kolibal, J.G.

1982-07-01

By altering the collision mechanism in the numerical transport calculations, and by constructing an analytical model based on age-diffusion theory, the outstanding feature in the life history of D-D fusion neutrons penetrating deeply into ordinary concrete is shown to be the transport in the 2.3 MeV oxygen anti-resonance. This result is used to assess the impact of the cross-section uncertainties and the uncertainties due to variations in the D-D fusion spectrum and temperature

Aerosols, Chemistry, and Radiative Forcing: A 3-D Model Analysis of Satellite and ACE-Asia data (ACMAP)

Science.gov (United States)

Chin, Mian; Ginoux, Paul; Torres, Omar; Zhao, Xue-Peng

2005-01-01

We propose a research project to incorporate a global 3-D model and satellite data into the multi-national Aerosol Characterization Experiment-Asia (ACE-Asia) mission. Our objectives are (1) to understand the physical, chemical, and optical properties of aerosols and the processes that control those properties over the Asian-Pacific region, (2) to investigate the interaction between aerosols and tropospheric chemistry, and (3) to determine the aerosol radiative forcing over the Asia-Pacific region. We will use the Georgia TecWGoddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model to link satellite observations and the ACE-Asia measurements. First, we will use the GOCART model to simulate aerosols and related species, and evaluate the model with satellite and in-situ observations. Second, the model generated aerosol vertical profiles and compositions will be used to validate the satellite products; and the satellite data will be used for during- and post- mission analysis. Third, we will use the model to analyze and interpret both satellite and ACE- Asia field campaign data and investigate the aerosol-chemistry interactions. Finally, we will calculate aerosol radiative forcing over the Asian-Pacific region, and assess the influence of Asian pollution in the global atmosphere. We propose a research project to incorporate a global 3-D model and satellite data into

X-ray and neutron diffuse scattering in LiNbO3 from 38 to 1200 K

International Nuclear Information System (INIS)

Zotov, N.; Mayer, H.M.; Guethoff, F.; Hohlwein, D.

1995-01-01

A semi-quantitative description of X-ray and neutron diffuse scattering from congruent lithium niobate, LiNbO 3 , is given. The diffuse scattering is concentrated in three sets of diffuse planes perpendicular to the pseudo-cubic symmetry-related [221], [241] and [ anti 4 anti 21] directions and can be attributed to one-dimensional displacive and chemical disorder along these directions. The variation of the X-ray and neutron diffuse intensities with the scattering vector, as well as the comparison between X-ray and neutron data, indicate that more than one type of atom is involved. Temperature variations are followed from 38 to 1200 K. Different disorder models are discussed. The increase of the integrated intensities of the diffuse lines along the [0 1k 2l] * and [0 anti 1k 4l] * directions (i.e. sections of the diffuse planes) up to 800 K followed by a slight decrease at higher temperatures may be interpreted either by static disorder related to temperature-dependent variation of disorder/defect clusters or by dynamic disorder. Inelastic neutron scattering experiments do not show any anomaly of the transversal acoustic (TA) modes. (orig.)

[Association of I/D and -786 Polymorphisms of ACE and NOS3 Genes With Features of the Course of Ischemic Heart Disease and Diabetes Mellitus Type 2].

Science.gov (United States)

Afanasiev, S A; Muslimova, E F; Rebrov, T Y; Sergienko, T N; Repin, A N

2016-09-01

to study relationship of ACE insertion-deletion (I/D) polymorphism and NOS3 T-786C polymorphism with characteristics of the course of ischemic heart disease (IHD) at the background of diabetes mellitus. Were examined 114 patients with IHD, 29.8% of patients had type 2 diabetes mellitus. ACE and NOS3 polymorphisms were determined by allele-specific polymerase chain reaction with primers by "Lytech". Patients with combined pathology belonged to older age group, had increased frequency of obesity and predominance of functional class II chronic heart failure. In this group we detected association of D allele of the ACE gene with higher frequency of dyslipidemia and obesity. Among patients with IHD without diabetes we observed associations of ACE I/D and NOS3 T-786C polymorphisms (close and moderate, respectively) with severity of effort angina. We also found that frequency of dyslipidemia among carriers of II and TT genotypes was lower than among carriers of other genotypes. Presence of type 2 diabetes as background pathology leads to a change of character of association of ACE I/D and NOS3 T-786C polymorphisms with clinical characteristics of patients with IHD.

1D to 3D diffusion-reaction kinetics of defects in crystals

DEFF Research Database (Denmark)

Trinkaus, H.; Heinisch, H.L.; Barashev, A.V.

2002-01-01

Microstructural features evolving in crystalline solids from diffusion-reaction kinetics of mobile components depend crucially on the dimension of the underlying diffusion process which is commonly assumed to be three-dimensional (3D). In metals, irradiation-induced displacement cascades produce...... clusters of self-interstitials performing 1D diffusion. Changes between equivalent 1D diffusion paths and transversal diffusion result in diffusion-reaction kinetics between one and three dimensions. An analytical approach suggests a single-variable function (master curve) interpolating between the 1D...

DWARF, 1-D Few-Group Neutron Diffusion with Thermal Feedback for Burnup and Xe Oscillation

International Nuclear Information System (INIS)

Anderson, E.C.; Putnam, G.E.

1975-01-01

1 - Description of problem or function: DWARF allows one-dimensional simulation of reactor burnup and xenon oscillation problems in slab, cylindrical, or spherical geometry using a few-group diffusion theory model. 2 - Method of solution: The few-group, neutron diffusion theory equations are reduced to a system of finite-difference equations that are solved for each group by the Gauss method at each time point. Fission neutron source iteration can be accelerated with Chebyshev extrapolation. A thermal feedback iterative loop is used to obtain consistent solutions for the distributions of reactor power, neutron flux, and fuel and coolant properties with the neutron group constants functions of the latter. Solutions for the new nuclide concentrations of a time-point are made with the flux assumed constant in the time interval. 3 - Restrictions on the complexity of the problem - Maxima of: 4 groups; 40 regions; 50 macroscopic materials (Only 10 are functions of the feedback variables); 50 nuclides per region; 250 mesh points

The evaluation of angiotensin-converting enzyme (ACE) gene I/D and IL-4 gene intron 3 VNTR polymorphisms in coronary artery disease.

Science.gov (United States)

Basol, Nursah; Celik, Atac; Karakus, Nevin; Ozturk, Sibel Demir; Ozsoy, Sibel Demir; Yigit, Serbulent

2014-01-01

Genetic polymorphism is a strong risk factor for coronary artery disease (CAD). In the present study, our aim was to evaluate angiotensin-converting enzyme (ACE) gene I/D polymorphism and interleukin-4 (IL-4) gene Intron 3 variable number of tandem repeat (VNTR) polymorphism in CAD. One hundred and twenty-four CAD patients and one hundred and twenty-three controls were enrolled. Genomic DNA was isolated and genotyped using polymerase chain reaction (PCR) analyses. The risk associated with inheriting the combined genotypes for the two polymorphisms were evaluated and it was found that the individuals who were P2P2-homozygous at IL-4 gene intron 3 VNTR and DD-homozygous at ACE gene I/D have a higher risk of developing CAD. Although, there is no correlation between IL4 VNTR polymorphism and ACE gene polymorphism and CAD, there is a strong association between CAD and co-existence of IL-4 VNTR and ACE gene polymorphisms in the Turkish population. Copyright © 2014 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Single Crystal Diffuse Neutron Scattering

Directory of Open Access Journals (Sweden)

Richard Welberry

2018-01-01

Full Text Available Diffuse neutron scattering has become a valuable tool for investigating local structure in materials ranging from organic molecular crystals containing only light atoms to piezo-ceramics that frequently contain heavy elements. Although neutron sources will never be able to compete with X-rays in terms of the available flux the special properties of neutrons, viz. the ability to explore inelastic scattering events, the fact that scattering lengths do not vary systematically with atomic number and their ability to scatter from magnetic moments, provides strong motivation for developing neutron diffuse scattering methods. In this paper, we compare three different instruments that have been used by us to collect neutron diffuse scattering data. Two of these are on a spallation source and one on a reactor source.

Characterization of the relationship between APOBEC3B deletion and ACE Alu insertion.

Directory of Open Access Journals (Sweden)

Kang Wang

Full Text Available The insertion/deletion (I/D polymorphism of the angiotensin converting enzyme (ACE, commonly associated with many diseases, is believed to have affected human adaptation to environmental changes during the out-of-Africa expansion. APOBEC3B (A3B, a member of the cytidine deaminase family APOBEC3s, also exhibits a variable gene insertion/deletion polymorphism across world populations. Using data available from published reports, we examined the global geographic distribution of ACE and A3B genotypes. In tracking the modern human dispersal routes of these two genes, we found that the variation trends of the two I/D polymorphisms were directly correlated. We observed that the frequencies of ACE insertion and A3B deletion rose in parallel along the expansion route. To investigate the presence of a correlation between the two polymorphisms and the effect of their interaction on human health, we analyzed 1199 unrelated Chinese adults to determine their genotypes and other important clinical characteristics. We discovered a significant difference between the ACE genotype/allele distribution in the A3B DD and A3B II/ID groups (P = 0.045 and 0.015, respectively, indicating that the ACE Alu I allele frequency in the former group was higher than in the latter group. No specific clinical phenotype could be associated with the interaction between the ACE and A3B I/D polymorphisms. A3B has been identified as a powerful inhibitor of Alu retrotransposition, and primate A3 genes have undergone strong positive selection (and expansion for restricting the mobility of endogenous retrotransposons during evolution. Based on these findings, we suggest that the ACE Alu insertion was enabled (facilitated by the A3B deletion and that functional loss of A3B provided an opportunity for enhanced human adaptability and survival in response to the environmental and climate challenges arising during the migration from Africa.

Deuterium short-range order in Pd0.975Ag0.025D0.685 by diffuse neutron scattering

DEFF Research Database (Denmark)

Blaschko, O.; Klemencic, R.; Fratzl, P.

1983-01-01

By diffuse neutron scattering the D short-range order in a Pd0.975Ag0.025D0.685 crystal was investigated at 50 and 70K. The results are compared with the D ordering in the PdDx system previously investigated, and it is shown that the isointensity contours around the (1/2,1,0) point are similar...

Huang diffuse scattering of neutrons

International Nuclear Information System (INIS)

Burkel, E.; Guerard, B. v.; Metzger, H.; Peisl, J.

1979-01-01

Huang diffuse neutron scattering was measured for the first time on niobium with interstitially dissolved deuterium as well as on MgO after neutron irradiation and Li 7 F after γ-irradiation. With Huang diffuse scattering the strength and symmetry of the distortion field around lattice defects can be determined. Our results clearly demonstrate that this method is feasible with neutrons. The present results are compared with X-ray experiments and the advantages of using neutrons is discussed in some detail. (orig.)

Use of MCAM in creating 3D neutronics model for ITER building

International Nuclear Information System (INIS)

Zeng Qin; Wang Guozhong; Dang Tongqiang; Long Pengcheng; Loughlin, Michael

2012-01-01

Highlights: ► We created a 3D neutronics model of the ITER building. ► The model was produced from the engineering CAD model by MCAM software. ► The neutron flux map in the ITER building was calculated. - Abstract: The three dimensional (3D) neutronics reference model of International Thermonuclear Experimental Reactor (ITER) only defines the tokamak machine and extends to the bio-shield. In order to meet further 3D neutronics analysis needs, it is necessary to create a 3D reference model of the ITER building. Monte Carlo Automatic Modeling Program for Radiation Transport Simulation (MCAM) was developed as a computer aided design (CAD) based bi-directional interface program between general CAD systems and Monte Carlo radiation transport simulation codes. With the help of MCAM version 4.8, the 3D neutronics model of ITER building was created based on the engineering CAD model. The calculation of the neutron flux map in ITER building during operation showed the correctness and usability of the model. This model is the first detailed ITER building 3D neutronics model and it will be made available to all international organization collaborators as a reference model.

Investigation on the neutron beam characteristics for boron neutron capture therapy with 3D and 2D transport calculations

International Nuclear Information System (INIS)

Kodeli, I.; Diop, C.M.; Nimal, J.C.

1994-01-01

In the framework of future Boron Neutron Capture Therapy (BNCT) experiments, where cells and animals irradiations are planned at the research reactor of Strasbourg University, the feasibility to obtain a suitable epithermal neutron beam is investigated. The neutron fluence and spectra calculations in the reactor are performed using the 3D Monte Carlo code TRIPOLI-3 and the 2D SN code TWODANT. The preliminary analysis of Al 2 O 3 and Al-Al 2 O 3 filters configurations are carried out in an attempt to optimize the flux characteristics in the beam tube facility. 7 figs., 7 refs

Associations of ACE Gene Insertion/Deletion Polymorphism, ACE Activity, and ACE mRNA Expression with Hypertension in a Chinese Population

Science.gov (United States)

He, Qingfang; Fan, Chunhong; Yu, Min; Wallar, Gina; Zhang, Zuo-Feng; Wang, Lixin; Zhang, Xinwei; Hu, Ruying

2013-01-01

Background The present study was designed to explore the association of angiotensin converting enzyme (ACE) gene insertion/deletion (I/D, rs4646994) polymorphism, plasma ACE activity, and circulating ACE mRNA expression with essential hypertension (EH) in a Chinese population. In addition, a new detection method for circulating ACE mRNA expression was explored. Methods The research was approved by the ethics committee of Zhejiang Provincial Center for Disease Prevention and Control. Written informed consent was obtained prior to the investigation. 221 hypertensives (cases) and 221 normotensives (controls) were interviewed, subjected to a physical examination, and provided blood for biochemical and genetic tests. The ACE mRNA expression was analyzed by real time fluorescent quantitative Reverse Transcription PCR (FQ-RT-PCR). We performed logistic regression to assess associations of ACE I/D genotypes, ACE activity, and ACE mRNA expression levels with hypertension. Results The results of the multivariate logistic regression analysis showed that the additive model (ID, DD versus II) of the ACE genotype revealed an association with hypertension with adjusted OR of 1.43(95% CI: 1.04-1.97), and ACE ID genotype with adjusted OR of 1.72(95% CI: 1.01-2.92), DD genotype with adjusted OR of 1.94(95% CI: 1.01-3.73), respectively. In addition, our data also indicate that plasma ACE activity (adjusted OR was 1.13(95% CI: 1.08-1.18)) was significantly related to hypertension. However, the plasma ACE mRNA expressions were not different between the cases and controls. Conclusion ACE I/D polymorphism and ACE activity revealed significant influence on hypertension, while circulating ACE mRNA expression was not important factors associated with hypertension in this Chinese population. The detection of circulating ACE mRNA expression by FQ-RT-PCR might be a useful method for early screening and monitoring of EH. PMID:24098401

Expression and evolutionary analyses of three acetylcholinesterase genes (Mi-ace-1, Mi-ace-2, Mi-ace-3) in the root-knot nematode Meloidogyne incognita.

Science.gov (United States)

Cui, Ruqiang; Zhang, Lei; Chen, Yuyan; Huang, Wenkun; Fan, Chengming; Wu, Qingsong; Peng, Deliang; da Silva, Washington; Sun, Xiaotang

2017-05-01

The full cDNA of Mi-ace-3 encoding an acetylcholinesterase (AChE) in Meloidogyne incognita was cloned and characterized. Mi-ace-3 had an open reading frame of 1875 bp encoding 624 amino acid residues. Key residues essential to AChE structure and function were conserved. The deduced Mi-ACE-3 protein sequence had 72% amino acid similarity with that of Ditylenchus destructor Dd-AChE-3. Phylogenetic analyses using 41 AChEs from 24 species showed that Mi-ACE-3 formed a cluster with 4 other nematode AChEs. Our results revealed that the Mi-ace-3 cloned in this study, which is orthologous to Caenorhabditis elegans AChE, belongs to the nematode ACE-3/4 subgroup. There was a significant reduction in the number of galls in transgenic tobacco roots when Mi-ace-1, Mi-ace-2, and Mi-ace-3 were knocked down simultaneously, whereas little or no effect were observed when only one or two of these genes were knocked down. This is an indication that the functions of these three genes are redundant. Copyright © 2017. Published by Elsevier Inc.

Angiotensin converting enzyme (ACE D/I) polymorphism and its ...

African Journals Online (AJOL)

Hepatitis C virus (HCV) infection is a global health problem in Egypt and causes different liver disease spectrum. Evidence indicates that angiotensin I converting enzyme (ACE) gene polymorphism may play a role in determining disease progression. We aimed to determine the association of ACE gene I/D polymorphism ...

Use of MCAM in creating 3D neutronics model for ITER building

Energy Technology Data Exchange (ETDEWEB)

Zeng Qin [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230027 (China); Wang Guozhong, E-mail: mango33@mail.ustc.edu.cn [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230027 (China); Dang Tongqiang [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230027 (China); Long Pengcheng [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230027 (China); Loughlin, Michael [ITER Organization, Route de Vinon sur Verdon, 13115 St. Paul-Lz-Durance (France)

2012-08-15

Highlights: Black-Right-Pointing-Pointer We created a 3D neutronics model of the ITER building. Black-Right-Pointing-Pointer The model was produced from the engineering CAD model by MCAM software. Black-Right-Pointing-Pointer The neutron flux map in the ITER building was calculated. - Abstract: The three dimensional (3D) neutronics reference model of International Thermonuclear Experimental Reactor (ITER) only defines the tokamak machine and extends to the bio-shield. In order to meet further 3D neutronics analysis needs, it is necessary to create a 3D reference model of the ITER building. Monte Carlo Automatic Modeling Program for Radiation Transport Simulation (MCAM) was developed as a computer aided design (CAD) based bi-directional interface program between general CAD systems and Monte Carlo radiation transport simulation codes. With the help of MCAM version 4.8, the 3D neutronics model of ITER building was created based on the engineering CAD model. The calculation of the neutron flux map in ITER building during operation showed the correctness and usability of the model. This model is the first detailed ITER building 3D neutronics model and it will be made available to all international organization collaborators as a reference model.

Diffuse scattering of neutrons and X-rays

International Nuclear Information System (INIS)

Novion, C.H. de

1978-01-01

Diffuse scattering is used to study defect concentrations of about 10 -4 in the case of X-rays and 10 -3 in the case of neutrons. The foundations of diffuse scattering formalism are given, some experimental devices described and a few applications discussed: study by diffraction on powders of defects in CeOsub(2-x); short-range order study by X-rays on Cusub(0.75) Ausub(0.25); short-range order study by neutrons on Cusub(0.435)Nisub(0.565); short-range order study by electrons TiOx; study of irradiation-induced self-interstitials in Al; study of holes created by neutrons in Al [fr

Numeric algorithms for parallel processors computer architectures with applications to the few-groups neutron diffusion equations

International Nuclear Information System (INIS)

Zee, S.K.

1987-01-01

A numeric algorithm and an associated computer code were developed for the rapid solution of the finite-difference method representation of the few-group neutron-diffusion equations on parallel computers. Applications of the numeric algorithm on both SIMD (vector pipeline) and MIMD/SIMD (multi-CUP/vector pipeline) architectures were explored. The algorithm was successfully implemented in the two-group, 3-D neutron diffusion computer code named DIFPAR3D (DIFfusion PARallel 3-Dimension). Numerical-solution techniques used in the code include the Chebyshev polynomial acceleration technique in conjunction with the power method of outer iteration. For inner iterations, a parallel form of red-black (cyclic) line SOR with automated determination of group dependent relaxation factors and iteration numbers required to achieve specified inner iteration error tolerance is incorporated. The code employs a macroscopic depletion model with trace capability for selected fission products' transients and critical boron. In addition to this, moderator and fuel temperature feedback models are also incorporated into the DIFPAR3D code, for realistic simulation of power reactor cores. The physics models used were proven acceptable in separate benchmarking studies

Interface requirements to couple thermal-hydraulic codes to 3D neutronic codes

Energy Technology Data Exchange (ETDEWEB)

Langenbuch, S.; Austregesilo, H.; Velkov, K. [GRS, Garching (Germany)] [and others

1997-07-01

The present situation of thermalhydraulics codes and 3D neutronics codes is briefly described and general considerations for coupling of these codes are discussed. Two different basic approaches of coupling are identified and their relative advantages and disadvantages are discussed. The implementation of the coupling for 3D neutronics codes in the system ATHLET is presented. Meanwhile, this interface is used for coupling three different 3D neutronics codes.

Interface requirements to couple thermal-hydraulic codes to 3D neutronic codes

International Nuclear Information System (INIS)

Langenbuch, S.; Austregesilo, H.; Velkov, K.

1997-01-01

The present situation of thermalhydraulics codes and 3D neutronics codes is briefly described and general considerations for coupling of these codes are discussed. Two different basic approaches of coupling are identified and their relative advantages and disadvantages are discussed. The implementation of the coupling for 3D neutronics codes in the system ATHLET is presented. Meanwhile, this interface is used for coupling three different 3D neutronics codes

ASSOCIATION OF ACTN3 R577X AND ACE I/D POLYMORPHISMS IN BRAZILIANS WRESTLERS

OpenAIRE

Ribas, Marcelo Romanovitch; Oliveira Netto, Zair Candido; Salgueirosa, Fabiano; Fernandes, Priscila; Matos, Oslei de; Bassan, Julio Cesar

2017-01-01

ABSTRACT Introduction: By associating genetics and sport, it is possible to identify subjects with greater capacity to adapt to training, and lower chances of injury. Objective: The investigation evaluated the genotypic and allelic distribution of ACTN3 R577X and ACE I/D polymorphisms in Brazilian high-performance athletes in wrestling and percussion combat sports. Methods: The study included 37 male athletes ranked from first to third place in world scenarios, divided into two groups: wrestl...

Measurement of the diffusion length of thermal neutrons in the beryllium oxide; Mesure de la longueur de diffusion des neutrons thermiques dans l'oxyde de beryllium

Energy Technology Data Exchange (ETDEWEB)

Koechlin, J C; Martelly, J; Duggal, V P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1955-07-01

The diffusion length of thermal neutrons in the beryllium oxide has been obtained while studying the spatial distribution of the neutrons in a massive parallelepiped of this matter placed before the thermal column of the reactor core of Saclay. The mean density of the beryllium oxide (BeO) is 2,95 gr/cm{sup 3}, the mean density of the massif is 2,92 gr/cm{sup 3}. The value of the diffusion length, deducted of the done measures, is: L = 32,7 {+-} 0,5 cm (likely gap). Some remarks are formulated about the influence of the spectral distribution of the neutrons flux used. (authors) [French] La longueur de diffusion des neutrons thermiques dans l'oxyde de beryllium a ete obtenue en etudiant la repartition spatiale des neutrons dans un massif parallelepipedique de cette matiere placee devant la colonne thermique de la Pile de Saclay. La densite moyenne de l'oxyde de beryllium (BeO) est de 2,95 gr/cm{sup 3}, la densite moyenne du massif de 2,92 gr/cm{sup 3}. La valeur de la longueur de diffusion, deduite des mesures effectuees est: L 32,7 {+-} 0,5 cm (ecart probable). Des remarques sont formulees quant a l'influence de la repartition spectrale du flux de neutrons utilise. (auteurs)

Generation of a library of two-group diffusion and kinetics parameters for DYN3D

International Nuclear Information System (INIS)

Petkov, P.T.; Christoskov, I.D.; Kamenov, K.; Antov, A.

2002-01-01

A library of two-group diffusion and kinetics parameters has been generated for the neutron kinetics code DYN3D for analysis of reactivity initiated accidents for the WWER-440 reactors, based on the MAGRU approximation methodology for the diffusion and kinetics parameters. The accuracy of this methodology has been tested and the conclusion is that it is not adequate. A new approximation methodology, based on interpolation for the most widely varying parameters, i.e. the moderator temperature and density, and on approximation for all other independent parameters, is presented. The methodology of calculation of the kinetics parameters using primary data from ENDF-B/VI is described in detail (Authors)

Radiosity diffusion model in 3D

Science.gov (United States)

Riley, Jason D.; Arridge, Simon R.; Chrysanthou, Yiorgos; Dehghani, Hamid; Hillman, Elizabeth M. C.; Schweiger, Martin

2001-11-01

We present the Radiosity-Diffusion model in three dimensions(3D), as an extension to previous work in 2D. It is a method for handling non-scattering spaces in optically participating media. We present the extension of the model to 3D including an extension to the model to cope with increased complexity of the 3D domain. We show that in 3D more careful consideration must be given to the issues of meshing and visibility to model the transport of light within reasonable computational bounds. We demonstrate the model to be comparable to Monte-Carlo simulations for selected geometries, and show preliminary results of comparisons to measured time-resolved data acquired on resin phantoms.

Designing an Epithermal Neutron Beam for Boron Neutron Capture Therapy for the Fusion Reactions 2H(d,n)3He and 3H(d,n)4He1

International Nuclear Information System (INIS)

Verbeke, J.M.; Costes, S.V.; Bleuel, D.; Vujic, J.; Leung, K.N.

1998-01-01

A beam shaping assembly has been designed to moderate high energy neutrons from the fusion reactions 2 H(d,N) 3 He and 3 H(d,n) 4 He for use fin boron neutron capture therapy. The low neutron yield of the 2 H(d,n) 3 He reaction led to unacceptably long treatment times. However, a 160 mA deuteron beam of energy 400 keV led to a treatment time of 120 minutes with the reaction 3 H(d,n) 4 He. Equivalent doses of 9.6 Gy-Eq and 21.9 Gy-Eq to the skin and to a 8 cm deep tumor respectively have been computed

Assessment of the relationship between ACE I/D gene polymorphism and renal allograft survival.

Science.gov (United States)

Yang, Chun-Hua; Lu, Yi; Chen, Xue-Xia; Xian, Wen-Feng; Tu, Wei-Feng; Li, Hong-Yan

2015-12-01

The relationship between the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) gene polymorphism and renal allograft survival after renal transplantation from the published reports are still debatable. This study was performed to evaluate the relationship between the ACE I/D gene polymorphism and renal allograft survival after renal transplantation using meta-analysis. Eligible studies were identified from PubMed and Cochrane Library on 1 November 2014, and eligible studies were recruited and synthesized using a meta-analysis methodology. Twelve investigations were included in this meta-analysis for the assessment of the relationship between the ACE I/D gene polymorphism and renal allograft survival. In this meta-analysis, the ACE I/D gene polymorphism was not associated with renal allograft survival after renal transplantation for overall populations, Caucasians, Brazilians and Africans. Interestingly, the ACE D allele and DD genotype were associated with renal allograft survival after renal transplantation in the Asian population. ACE D allele and DD genotype were associated with renal allograft survival after renal transplantation in the Asian population. However, more studies should be performed to confirm this association. © The Author(s) 2015.

Relationship between major depressive disorder and ACE gene I/D polymorphism in a Turkish population

Directory of Open Access Journals (Sweden)

Sema Inanir

2016-04-01

Full Text Available Abstract Background Major depressive disorder (MDD is a complex disease and a significant health problem that is prevalent across the world. Angiotensin-converting enzyme (ACE has an important role in renin-angiotensin system (RAS and converts inactive angiotensin I to a potent vasopressor and aldosterone-stimulating peptide angiotensin II. Levels of ACE in plasma vary according to the insertion/deletion (I/D polymorphism of ACE gene. Objective The aim of the current study was to examine the influence ACE gene I/D variations on the risk of MDD. Methods In the present case-control study, we analyzed ACE I/D polymorphism in 346 MDD patients and 210 healthy subjects using polymerase chain reaction technique. Results Comparing the two groups, no significant difference was observed with regard to either genotype distributions or allele frequencies of the I/D polymorphism of ACE gene. Discussion Our findings suggest that the ACE I/D polymorphism is not associated with MDD in Turkish case-control study. Further studies are still needed.

Neutron transport equation - indications on homogenization and neutron diffusion

International Nuclear Information System (INIS)

Argaud, J.P.

1992-06-01

In PWR nuclear reactor, the practical study of the neutrons in the core uses diffusion equation to describe the problem. On the other hand, the most correct method to describe these neutrons is to use the Boltzmann equation, or neutron transport equation. In this paper, we give some theoretical indications to obtain a diffusion equation from the general transport equation, with some simplifying hypothesis. The work is organised as follows: (a) the most general formulations of the transport equation are presented: integro-differential equation and integral equation; (b) the theoretical approximation of this Boltzmann equation by a diffusion equation is introduced, by the way of asymptotic developments; (c) practical homogenization methods of transport equation is then presented. In particular, the relationships with some general and useful methods in neutronic are shown, and some homogenization methods in energy and space are indicated. A lot of other points of view or complements are detailed in the text or the remarks

Diffusion Parameters of BeO by the Pulsed Neutron Method

International Nuclear Information System (INIS)

Joshi, B.V.; Nargundkar, V.R.; Subbarao, K.

1965-01-01

The use of the pulsed neutron method for the precise determination of the diffusion parameters of moderators is described. The diffusion parameters of BeO have been obtained by this method. The neutron bursts were produced from a cascade accelerator by pulsing the ion source and using the Be (d, n) reaction. The detector was an enriched boron trifluoride proportional counter. It is shown that by a proper choice of the counter position arid length, and the source position, most of the space harmonics can be eliminated. Any constant background can be accounted for in the calculation of the decay constant. Very large bucklings were not used to avoid time harmonics. Any remaining harmonic content was rendered ineffective by the use of adequate time delay. The decay constant of the fundamental mode of the thermal neutron population was determined for several bucklings. Conditions to be satisfied for an accurate determination of the diffusion cooling constant C are discussed. The following values are obtained for BeO: λ 0 = absorption constant = 156.02 ± 4.37 s -1 D = diffusion coefficient = (1.3334 ± 0.0128) x 10 5 cm 2 /s C = diffusion cooling constant = (-4.8758 ± 0.5846) x 10 5 cm 4 /s. The effect of neglecting the contribution of the B 6 term on the determination of the diffusion parameters was estimated and is shown to be considerable. The reason for the longstanding discrepancy between the values of C obtained for the same moderator by different workers is attributed to this. (author) [fr

On the numerical solution of the neutron fractional diffusion equation

International Nuclear Information System (INIS)

Maleki Moghaddam, Nader; Afarideh, Hossein; Espinosa-Paredes, Gilberto

2014-01-01

Highlights: • The new version of neutron diffusion equation which established on the fractional derivatives is presented. • The Neutron Fractional Diffusion Equation (NFDE) is solved in the finite differences frame. • NFDE is solved using shifted Grünwald-Letnikov definition of fractional operators. • The results show that “K eff ” strongly depends on the order of fractional derivative. - Abstract: In order to core calculation in the nuclear reactors there is a new version of neutron diffusion equation which is established on the fractional partial derivatives, named Neutron Fractional Diffusion Equation (NFDE). In the NFDE model, neutron flux in each zone depends directly on the all previous zones (not only on the nearest neighbors). Under this circumstance, it can be said that the NFDE has the space history. We have developed a one-dimension code, NFDE-1D, which can simulate the reactor core using arbitrary exponent of differential operators. In this work a numerical solution of the NFDE is presented using shifted Grünwald-Letnikov definition of fractional derivative in finite differences frame. The model is validated with some numerical experiments where different orders of fractional derivative are considered (e.g. 0.999, 0.98, 0.96, and 0.94). The results show that the effective multiplication factor (K eff ) depends strongly on the order of fractional derivative

Domain decomposition methods for the neutron diffusion problem

International Nuclear Information System (INIS)

Guerin, P.; Baudron, A. M.; Lautard, J. J.

2010-01-01

The neutronic simulation of a nuclear reactor core is performed using the neutron transport equation, and leads to an eigenvalue problem in the steady-state case. Among the deterministic resolution methods, simplified transport (SPN) or diffusion approximations are often used. The MINOS solver developed at CEA Saclay uses a mixed dual finite element method for the resolution of these problems. and has shown his efficiency. In order to take into account the heterogeneities of the geometry, a very fine mesh is generally required, and leads to expensive calculations for industrial applications. In order to take advantage of parallel computers, and to reduce the computing time and the local memory requirement, we propose here two domain decomposition methods based on the MINOS solver. The first approach is a component mode synthesis method on overlapping sub-domains: several Eigenmodes solutions of a local problem on each sub-domain are taken as basis functions used for the resolution of the global problem on the whole domain. The second approach is an iterative method based on a non-overlapping domain decomposition with Robin interface conditions. At each iteration, we solve the problem on each sub-domain with the interface conditions given by the solutions on the adjacent sub-domains estimated at the previous iteration. Numerical results on parallel computers are presented for the diffusion model on realistic 2D and 3D cores. (authors)

Compact D-D/D-T neutron generators and their applications

International Nuclear Information System (INIS)

Lou, Tak Pui

2003-01-01

Neutron generators based on the 2 H(d,n) 3 He and 3 H(d,n) 4 He fusion reactions are the most commonly available neutron sources. The applications of current commercial neutron generators are often limited by their low neutron yield and their short operational lifetime. A new generation of D-D/D-T fusion-based neutron generators has been designed at Lawrence Berkeley National Laboratory (LBNL) by using high current ion beams hitting on a self-loading target that has a large surface area to dissipate the heat load. This thesis describes the rationale behind the new designs and their potential applications. A survey of other neutron sources is presented to show their advantages and disadvantages compared to the fusion-based neutron generator. A prototype neutron facility was built at LBNL to test these neutron generators. High current ion beams were extracted from an RF-driven ion source to produce neutrons. With an average deuteron beam current of 24 mA and an energy of 100 keV, a neutron yield of >10 9 n/s has been obtained with a D-D coaxial neutron source. Several potential applications were investigated by using computer simulations. The computer code used for simulations and the variance reduction techniques employed were discussed. A study was carried out to determine the neutron flux and resolution of a D-T neutron source in thermal neutron scattering applications for condensed matter experiments. An error analysis was performed to validate the scheme used to predict the resolution. With a D-T neutron yield of 10 14 n/s, the thermal neutron flux at the sample was predicted to be 7.3 x 10 5 n/cm 2 s. It was found that the resolution of cold neutrons was better than that of thermal neutrons when the duty factor is high. This neutron generator could be efficiently used for research and educational purposes at universities. Additional applications studied were positron production and Boron Neutron Capture Therapy (BNCT). The neutron flux required for positron

Generalization of the Fourier Convergence Analysis in the Neutron Diffusion Eigenvalue Problem

International Nuclear Information System (INIS)

Lee, Hyun Chul; Noh, Jae Man; Joo, Hyung Kook

2005-01-01

Fourier error analysis has been a standard technique for the stability and convergence analysis of linear and nonlinear iterative methods. Lee et al proposed new 2- D/1-D coupling methods and demonstrated several advantages of the new methods by performing a Fourier convergence analysis of the methods as well as two existing methods for a fixed source problem. We demonstrated the Fourier convergence analysis of one of the 2-D/1-D coupling methods applied to a neutron diffusion eigenvalue problem. However, the technique cannot be used directly to analyze the convergence of the other 2-D/1-D coupling methods since some algorithm-specific features were used in our previous study. In this paper we generalized the Fourier convergence analysis technique proposed and analyzed the convergence of the 2-D/1-D coupling methods applied to a neutron diffusion Eigenvalue problem using the generalized technique

Aerobic exercise training differentially affects ACE C- and N-domain activities in humans: Interactions with ACE I/D polymorphism and association with vascular reactivity.

Science.gov (United States)

Alves, Cléber Rene; Fernandes, Tiago; Lemos, José Ribeiro; Magalhães, Flávio de Castro; Trombetta, Ivani Credidio; Alves, Guilherme Barreto; Mota, Glória de Fátima Alves da; Dias, Rodrigo Gonçalves; Pereira, Alexandre Costa; Krieger, José Eduardo; Negrão, Carlos Eduardo; Oliveira, Edilamar Menezes

2018-01-01

Previous studies have linked angiotensin-converting enzyme ( ACE) insertion (I)/deletion (D) polymorphism (II, ID and DD) to physical performance. Moreover, ACE has two catalytic domains: NH2 (N) and COOH (C) with distinct functions, and their activity has been found to be modulated by ACE polymorphism. The aim of the present study is to investigate the effects of the interaction between aerobic exercise training (AET) and ACE I/D polymorphism on ACE N- and C-domain activities and vascular reactivity in humans. A total of 315 pre-selected healthy males were genotyped for II, ID and DD genotypes. Fifty completed the full AET (II, n = 12; ID, n = 25; and DD, n = 13), performed in three 90-minute sessions weekly, in the four-month exercise protocol. Pre- and post-training resting heart rate (HR), peak O 2 consumption (VO 2 peak), mean blood pressure (MBP), forearm vascular conduction (FVC), total circulating ACE and C- and N-domain activities were assessed. One-way ANOVA and two -way repeated-measures ANOVA were used. In pre-training, all variables were similar among the three genotypes. In post-training, a similar increase in FVC (35%) was observed in the three genotypes. AET increased VO 2 peak similarly in II, ID and DD (49±2 vs. 57±1; 48±1 vs. 56±3; and 48±5 vs. 58±2 ml/kg/min, respectively). Moreover, there were no changes in HR and MBP. The DD genotype was also associated with greater ACE and C-domain activities at pre- and post-training when compared to II. AET decreased similarly the total ACE and C-domain activities in all genotypes, while increasing the N-domain activity in the II and DD genotypes. However, interestingly, the measurements of N-domain activity after training indicate a greater activity than the other genotypes. These results suggest that the vasodilation in response to AET may be associated with the decrease in total ACE and C-domain activities, regardless of genotype, and that the increase in N-domain activity is dependent on the DD

CALTRANS: A parallel, deterministic, 3D neutronics code

Energy Technology Data Exchange (ETDEWEB)

Carson, L.; Ferguson, J.; Rogers, J.

1994-04-01

Our efforts to parallelize the deterministic solution of the neutron transport equation has culminated in a new neutronics code CALTRANS, which has full 3D capability. In this article, we describe the layout and algorithms of CALTRANS and present performance measurements of the code on a variety of platforms. Explicit implementation of the parallel algorithms of CALTRANS using both the function calls of the Parallel Virtual Machine software package (PVM 3.2) and the Meiko CS-2 tagged message passing library (based on the Intel NX/2 interface) are provided in appendices.

MSLB coupled 3D neutronics-thermalhydraulic analysis of a large PWR using RELAP5-3D

International Nuclear Information System (INIS)

Lo Nigro, A.; Spadoni, A.; D'Auria, F.; Saiu, G.

2001-01-01

A RELAP5-3D model of the Westinghouse AP1000 NSSS has been set up and it has been used to analyze the MSLB accident. Main results (both spatial distributions and time trends) have been represented with 3D plots and graphical movies. The method applied allows accounting for the coupled 3D neutronics and thermalyhdraulics effects, suggesting to consider its applicability in Safety Analysis.(author)

Theoretical study of the paramagnetic scattering of neutrons; Etude theorique de la diffusion paramagnetique des neutrons

Energy Technology Data Exchange (ETDEWEB)

Saint-James, D [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1962-02-15

diverses diffusions (elastique et inelastiques) est calculee pour les terres rares soumises a l'action d'un champ cristallin de symetrie cubique, pour les sesquioxydes d'holmium et d'erbium et pour le chlorure ferreux anhydre (Cl{sub 2}Fe). Elle est suffisamment forte pour permettre une detection experimentale, fournissant ainsi une determination directe de la distance des niveaux par mesure de la variation de longueur d'onde du neutron. Il est, de plus, remarquable que, dans le cas du neodyme, de l'holium et de l'erbium, la section efficace totale calculee pour des neutrons de longueur d'onde aux alentours de l'angstrom soit peu sensible aux effets du champ cristallin. On compare les resultats des calculs ci-dessus aux etudes experimentales existantes. On examine egalement l'influence du moment orbital sur la dependance angulaire de la diffusion pour des ions polarises. La loi I = I{sub 0}sin{sup 2}{beta} n'est qu'approchee; on en donne les limites de validite. On envisage enfin l'influence des interactions d'echange entre les ions magnetiques. Les raies de diffusion elastiques et inelastiques sont elargies. Le comportement de la largeur de raie, avec la longueur du vecteur de diffusion k, est different de celui obtenu dans le cas ou le niveau fondamental de l'ion magnetique est defini par un moment cinetique J . La largeur de raie ne tend pas vers zero avec K. (auteur)

Compact D-D/D-T neutron generators and their applications

Energy Technology Data Exchange (ETDEWEB)

Lou, Tak Pui [Univ. of California, Berkeley, CA (United States)

2003-01-01

Neutron generators based on the ²H(d,n)³He and ³H(d,n)⁴He fusion reactions are the most commonly available neutron sources. The applications of current commercial neutron generators are often limited by their low neutron yield and their short operational lifetime. A new generation of D-D/D-T fusion-based neutron generators has been designed at Lawrence Berkeley National Laboratory (LBNL) by using high current ion beams hitting on a self-loading target that has a large surface area to dissipate the heat load. This thesis describes the rationale behind the new designs and their potential applications. A survey of other neutron sources is presented to show their advantages and disadvantages compared to the fusion-based neutron generator. A prototype neutron facility was built at LBNL to test these neutron generators. High current ion beams were extracted from an RF-driven ion source to produce neutrons. With an average deuteron beam current of 24 mA and an energy of 100 keV, a neutron yield of >10⁹ n/s has been obtained with a D-D coaxial neutron source. Several potential applications were investigated by using computer simulations. The computer code used for simulations and the variance reduction techniques employed were discussed. A study was carried out to determine the neutron flux and resolution of a D-T neutron source in thermal neutron scattering applications for condensed matter experiments. An error analysis was performed to validate the scheme used to predict the resolution. With a D-T neutron yield of 10¹⁴ n/s, the thermal neutron flux at the sample was predicted to be 7.3 x 10⁵ n/cm²s. It was found that the resolution of cold neutrons was better than that of thermal neutrons when the duty factor is high. This neutron generator could be efficiently used for research and educational purposes at universities. Additional applications studied were positron production and

ACE and ACTN3 genes polymorphisms among female Hungarian athletes in the aspect of sport disciplines.

Science.gov (United States)

Bosnyák, E; Trájer, E; Udvardy, A; Komka, Z; Protzner, A; Kováts, T; Györe, I; Tóth, M; Pucsok, J; Szmodis, M

2015-12-01

The aim of the study was to determine the importance of two sport-associated gene polymorphisms, alpha-actinin-3 R577X (ACTN3) and angiotensin-converting enzyme I/D (ACE), among Hungarian athletes in different sports. The examination was carried out only on women (n = 100). Sport-specific groups were formed in order to guarantee the most homogeneous clusters. Human genomic DNA was isolated from blood, and genotyping was performed by polymerase chain reaction. To measure the differences between the participating groups, Chi-squared test was performed using Statistica 9.0 for Windows® (significance level: p ACE I/D allele frequencies, significant difference was detected between water polo (I = 61.11%; D = 38.89%) and combat sports (I = 35.71%, D = 64.29%) athletes (p ACE I/D alleles in combat sports and kayaking/rowing (p > 0.05) were compared. A similarity was detectable in the I allele frequencies of the water polo (61.11%) and kayaking/rowing (56.67%) groups. The ACTN3 R/X polymorphism showed no differences in comparison with the sport groups. R allele frequencies were higher in every group compared to the X allele. The potential significance of the ACE I allele in sports of an aerobic nature was not clearly confirmed among Hungarian athletes.

Development of ITER 3D neutronics model and nuclear analyses

International Nuclear Information System (INIS)

Zeng, Q.; Zheng, S.; Lu, L.; Li, Y.; Ding, A.; Hu, H.; Wu, Y.

2007-01-01

ITER nuclear analyses rely on the calculations with the three-dimensional (3D) Monte Carlo code e.g. the widely-used MCNP. However, continuous changes in the design of the components require the 3D neutronics model for nuclear analyses should be updated. Nevertheless, the modeling of a complex geometry with MCNP by hand is a very time-consuming task. It is an efficient way to develop CAD-based interface code for automatic conversion from CAD models to MCNP input files. Based on the latest CAD model and the available interface codes, the two approaches of updating 3D nuetronics model have been discussed by ITER IT (International Team): The first is to start with the existing MCNP model 'Brand' and update it through a combination of direct modification of the MCNP input file and generation of models for some components directly from the CAD data; The second is to start from the full CAD model, make the necessary simplifications, and generate the MCNP model by one of the interface codes. MCAM as an advanced CAD-based MCNP interface code developed by FDS Team in China has been successfully applied to update the ITER 3D neutronics model by adopting the above two approaches. The Brand model has been updated to generate portions of the geometry based on the newest CAD model by MCAM. MCAM has also successfully performed conversion to MCNP neutronics model from a full ITER CAD model which is simplified and issued by ITER IT to benchmark the above interface codes. Based on the two updated 3D neutronics models, the related nuclear analyses are performed. This paper presents the status of ITER 3D modeling by using MCAM and its nuclear analyses, as well as a brief introduction of advanced version of MCAM. (authors)

Diffuse scattering of neutrons

International Nuclear Information System (INIS)

Novion, C.H. de.

1981-02-01

The use of neutron scattering to study atomic disorder in metals and alloys is described. The diffuse elastic scattering of neutrons by a perfect crystal lattice leads to a diffraction spectrum with only Bragg spreads. the existence of disorder in the crystal results in intensity and position modifications to these spreads, and above all, to the appearance of a low intensity scatter between Bragg peaks. The elastic scattering of neutrons is treated in this text, i.e. by measuring the number of scattered neutrons having the same energy as the incident neutrons. Such measurements yield information on the static disorder in the crystal and time average fluctuations in composition and atomic displacements [fr

The ACE gene D/I polymorphism as a modulator of severity of cystic fibrosis

Directory of Open Access Journals (Sweden)

Marson Fernando A L

2012-08-01

Full Text Available Abstract Background Cystic Fibrosis (CF is a monogenic disease with complex expression because of the action of genetic and environmental factors. We investigated whether the ACE gene D/I polymorphism is associated with severity of CF. Methods A cross-sectional study was performed, from 2009 to 2011, at University of Campinas – UNICAMP. We analyzed 180 patients for the most frequent mutations in the CFTR gene, presence of the ACE gene D/I polymorphism and clinical characteristics of CF. Results There was an association of the D/D genotype with early initiation of clinical manifestations (OR: 1.519, CI: 1.074 to 2.146, bacterium Burkholderia cepacia colonization (OR: 3.309, CI: 1.476 to 6.256 and Bhalla score (BS (p = 0.015. The association was observed in subgroups of patients which were defined by their CFTR mutation genotype (all patients; subgroup I: no mutation detected; subgroup II: one CFTR allele identified to mutation class I, II or III; subgroup III: both CFTR alleles identified to mutation class I, II and/or III. Conclusion An association between the D allele in the ACE gene and the severity of CF was found in our study.

ACE Gene I/D Polymorphism and Obesity in 1,574 Patients with Type 2 Diabetes Mellitus.

Science.gov (United States)

Pan, Yan-Hong; Wang, Min; Huang, Yan-Mei; Wang, Ying-Hui; Chen, Yin-Ling; Geng, Li-Jun; Zhang, Xiao-Xi; Zhao, Hai-Lu

2016-01-01

Association between ACE gene I/D polymorphism and the risk of overweight/obesity remains controversial. We investigated the possible relationship between ACE gene I/D polymorphism and obesity in Chinese type 2 diabetes mellitus (T2DM) patients. In this study, obesity was defined as a body mass index (BMI) value ≥ 25 kg/m 2 and subjects were classified into 4 groups (lean, normal, overweight, and obese). PCR (polymerase chain reaction) was used to detect the ACE gene I/D polymorphism in T2DM patients. Metabolic measurements including blood glucose, lipid profile, and blood pressure were obtained. Frequencies of the ACE genotypes (DD, ID, and II) were not significant among the 4 groups of BMI-defined patients ( P = 0.679) while ACE II carriers showed higher systolic blood pressure (SBP) and pulse pressure (PP) (all P ACE gene I/D polymorphism with obesity is insignificant in Chinese patients with T2DM. SBP and PP might be higher in the ACE II carriers than in the DD and ID carriers.

Analysis of diffuse scattering in neutron powder diagrams. Application to glassy carbon

International Nuclear Information System (INIS)

Boysen, H.

1985-01-01

From the quantitative analysis of the diffuse scattered intensity in powder diagrams valuable information about the disorder in crystals may be obtained. According to the dimensionality of this disorder (0D, 1D, 2D or 3D corresponding to diffuse peaks, streaks, planes or volume in reciprocal space) a characteristic modulation of the background is observed, which is described by specific functions. These are derived by averaging the appropriate cross sections over all crystallite orientations in the powder and folding with the resolution function of the instrument. If proper account is taken of all proportionality factors different components of the background can be put on one relative scale. The results are applied to two samples of glassy carbon differing in their degree of disorder. The neutron powder patterns contain contributions from 0D (00l peaks due to the stacking of graphitic layers), 1D (hkzeta streaks caused by the random orientation of these layers) and 3D (incoherent scattering, averaged thermal diffuse scattering, multiple scattering). From the fit to the observed data various parameters of the disorder like domain sizes, strains, interlayer distances, amount of incorporated hydrogen, pore sizes etc. are determined. It is shown that the omission of resolution corrections leads to false parameters. (orig.)

Study by neutron diffusion of magnetic fluctuations in iron in the curie temperature region; Etude des fluctuations d'aimantation dans le fer au voisinage de la temperature de curie par diffusion des neutrons

Energy Technology Data Exchange (ETDEWEB)

Ericson-Galula, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-12-15

Heinsenberg model and a simple band model; our values in good agreement with those calculated in the Heisenberg model and exclude the band model used. Finally, in chapter IV we recall the chief results obtained. (author) [French] La diffusion critique des neutrons dans le fer est due aux fluctuations d'aimantation qui existent dans les substances ferromagnetiques au voisinage de la temperature de Curie. Les fluctuations peuvent se decrire en termes de correlations; on definit une fonction de correlation: {gamma}{sub R{sub vector}} (t), {gamma}{sub R{sub vector}} (t) , valeur moyenne du produit scalaire d'un spin de reference et d'un spin situe a la distance (R) du premier et considere a l'instant t. Dans le chapitre I nous rappelons les generalites sur les sections efficaces de diffusion des neutrons; nous donnons un bref resume de la theorie de VAN HOVE qui a montre que la section efficace de diffusion magnetique des neutrons est la transformee de FOURIER de la fonction de correlation. Dans le chapitre II nous etudions la dependance spatiale de la fonction de correlation, supposee independante du temps. On peut alors la caracteriser par deux parametres K{sub 1} et r{sub 1} qui permettent de calculer respectivement la portee et l'intensite des correlations. Apres avoir expose le principe de la mesure de ces parametres, nous decrirons l'appareillage experimental. Les valeurs experimentales obtenues sont en bon accord avec celles calculees, l'accord est meilleur si on suppose que ce sont les deuxiemes et non les premiers voisins d'un atome de fer qui sont magnetiquement actifs, ainsi que l'a propose NEEL. Dans le chapitre III nous etudions l'evolution dans le temps de la fonction de correlation; cette evolution est caracterisee par un parametre {lambda} dependant de la temperature, qui intervient dans l'equation de diffusion, a laquelle obeissent les fluctuations d'aimantation {delta}M{sub vector}/{delta}t = {lambda} {nabla

Association of Angiotensin-Converting Enzyme ACE Gene Polymorphism with ACE Activity and Susceptibility to Vitiligo in Egyptian Population.

Science.gov (United States)

Badran, Dahlia I; Nada, Hesham; Hassan, Ranya

2015-05-01

The insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene is associated with vitiligo in the Indians and Koreans, but not in those of English or Turkish background. We investigated the ACE (I/D) polymorphism in vitiligo patients for the first time in Egypt and compared serum ACE levels between vitiligo patients and controls. The present study was carried out in 100 vitiligo patients (40 males and 60 females) and in 100 healthy controls of an Egyptian population using the polymerase chain reaction genotyping method. The ACE genotype and allele frequency was significantly different between vitiligo patients and controls. Our results revealed a significant increase in the frequency of the ACE I allele (p=0.002; odds ratio: 1.99; 95% confidence intervals: 1.207-3.284) with an overrepresentation of I/D genotype in the vitiligo patient group. Furthermore, there was a significant difference between the segmental, nonsegmental, and focal vitiligo in ACE gene genotype distribution. Serum ACE levels were significantly increased in vitiligo patients compared to controls (p=0.034). This study suggests that, for the first time, ACE gene polymorphism confers susceptibility to vitiligo in the Egyptian population.

VARI-QUIR-3, 2-D Multigroup Steady-State Neutron Diffusion in X-Y R-Z or R-Theta Geometry

International Nuclear Information System (INIS)

Collier, George

1984-01-01

1 - Nature of physical problem solved: The steady-state, multigroup, two-dimensional neutron diffusion equations are solved in x-y, r-z, and r-theta geometry. 2 - Method of solution: A Gauss-Seidel type of solution with inner and outer iterations is used. The source is held constant during the inner iterations

Measurement of the diffusion length of thermal neutrons inside graphite; Mesure de la longueur de diffusion des neutrons thermiques dans le graphite

Energy Technology Data Exchange (ETDEWEB)

Ertaud, A; Beauge, R; Fauquez, H; De Laboulay, H; Mercier, C; Vautrey, L

1948-11-01

The diffusion length of thermal neutrons inside a given industrial graphite is determined by measuring the neutron density inside a parallelepipedal piling up of graphite bricks (2.10 x 2.10 x 2.442 m). A 3.8 curies (Ra {alpha} {yields} Be) source is placed inside the parallelepipedal block of graphite and thin manganese detectors are used. Corrections are added to the unweighted measurements to take into account the effects of the damping of supra-thermal neutrons in the measurement area. These corrections are experimentally deduced from the differential measurements made with a cadmium screen interposed between the source and the first plane of measurement. An error analysis completes the report. The diffusion length obtained is: L = 45.7 cm {+-} 0.3. The average density of the graphite used is 1.76 and the average apparent density of the piling up is 1.71. (J.S.)

Linear extended neutron diffusion theory for semi-in finites homogeneous means

International Nuclear Information System (INIS)

Vazquez R, R.; Vazquez R, A.; Espinosa P, G.

2009-10-01

Originally developed for heterogeneous means, the linear extended neutron diffusion theory is applied to the limit case of monoenergetic neutron diffusion in a semi-infinite homogeneous mean with a neutron source, located in the coordinate origin situated in the frontier of dispersive material. The monoenergetic neutron diffusion is studied taking into account the spatial deviations in the neutron flux to the interfacial current caused by the neutron source, as well as the influence of the spatial deviations in the absorption rate. The developed pattern is an unidimensional model for an energy group obtained of application of volumetric average diffusion equation in the moderator. The obtained results are compared against the classic diffusion theory and qualitatively against the neutron transport theory. (Author)

Insertion/deletion polymorphism of the ACE gene and adherence to ACE inhibitors

NARCIS (Netherlands)

Schelleman, H; Klungel, O H; van Duijn, C M; Witteman, J C M; Hofman, A; de Boer, A; Stricker, B H Ch

AIMS: We investigated whether the insertion/deletion (I/D) polymorphism of the ACE gene modified the adherence to ACE inhibitors as measured by the discontinuation of an ACE inhibitor, or addition of another antihypertensive drug. METHODS: This was a cohort study among 239 subjects who started ACE

Diffuse neutron scattering signatures of rough films

International Nuclear Information System (INIS)

Pynn, R.; Lujan, M. Jr.

1992-01-01

Patterns of diffuse neutron scattering from thin films are calculated from a perturbation expansion based on the distorted-wave Born approximation. Diffuse fringes can be categorised into three types: those that occur at constant values of the incident or scattered neutron wavevectors, and those for which the neutron wavevector transfer perpendicular to the film is constant. The variation of intensity along these fringes can be used to deduce the spectrum of surface roughness for the film and the degree of correlation between the film's rough surfaces

Coupled 3D neutronics/thermal hydraulics modeling of the SAFARI-1 MTR

International Nuclear Information System (INIS)

Rosenkrantz, Adam; Avramova, Maria; Ivanov, Kostadin; Prinsloo, Rian; Botes, Danniëll; Elsakhawy, Khalid

2014-01-01

Highlights: • Development of 3D coupled neutronics/thermal–hydraulic model of SAFARI-1. • Verification of 3D steady-state NEM based neutronics model for SAFARI-1. • Verification of 3D COBRA-TF based thermal–hydraulic model of SAFARI-1. • Quantification of the effect of correct modeling of thermal–hydraulic feedback. - Abstract: The purpose of this study was to develop a coupled accurate multi-physics model of the SAFARI-1 Material Testing Reactor (MTR), a facility that is used for both research and the production of medical isotopes. The model was developed as part of the SAFARI-1 benchmarking project as a cooperative effort between the Pennsylvania State University (PSU) and the South African Nuclear Energy Corporation (Necsa). It was created using a multi-physics coupling of state of the art nuclear reactor simulation tools, consisting of a neutronics code and a thermal hydraulics code. The neutronics tool used was the PSU code NEM, and the results from this component were verified using the Necsa neutronics code OSCAR-4, which is utilized for SAFARI-1 core design and fuel management. On average, the multiplication factors of the neutronics models agreed to within 5 pcm and the radial assembly-averaged powers agreed to within 0.2%. The thermal hydraulics tool used was the PSU version of COBRA-TF (CTF) sub-channel code, and the results of this component were verified against another thermal hydraulics code, the RELAP5-3D system code, used at Necsa for thermal–hydraulics analysis of SAFARI-1. Although only assembly-averaged results from RELAP5-3D were available, they fell within the range of values for the corresponding assemblies in the comprehensive CTF solution. This comparison allows for the first time to perform a quantification of steady-state errors for a low-powered MTR with an advanced thermal–hydraulic code such as CTF on a per-channel basis as compared to simpler and coarser-mesh RELAP5-3D modeling. Additionally, a new cross section

Telomere length is associated with ACE I/D polymorphism in hypertensive patients with left ventricular hypertrophy

DEFF Research Database (Denmark)

Fyhrquist, Frej; Eriksson, Anders; Saijonmaa, Outi

2013-01-01

INTRODUCTION: Short telomeres are often associated with cardiovascular risk factors and age-related diseases, while the angiotensin converting enzyme (ACE) gene insertion/deletion polymorphism (DD, ID, II) has shown such associations less consistently. We hypothesized that telomere length...... and association of telomere length with cardiovascular risk is affected by ACE (I/D) genotype. METHODS: We measured leucocyte telomere length (LTL) by Southern blot and analysed ACE I/D genotypes in 1249 subjects with hypertension and left ventricular hypertrophy (LVH). We examined interactions of ACE I...

ACE I/D polymorphism in Indian patients with hypertrophic cardiomyopathy and dilated cardiomyopathy

DEFF Research Database (Denmark)

Rai, Taranjit Singh; Dhandapany, Perundurai Subramaniam; Ahluwalia, Tarun Veer Singh

2008-01-01

The study was carried to determine the association of angiotensin converting enzyme (ACE) insertion/deletion (I/D) polymorphism with the risk of hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and restrictive cardiomyopathy (RCM).......The study was carried to determine the association of angiotensin converting enzyme (ACE) insertion/deletion (I/D) polymorphism with the risk of hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and restrictive cardiomyopathy (RCM)....

Production of 14 MeV neutrons from D-D neutron generators

International Nuclear Information System (INIS)

Cecil, F.E.; Nieschmidt, E.B.

1986-01-01

The production of 14 MeV neutrons from a D-D neutron generator resulting from tritium buildup from the d(d,p)t reaction in the target is discussed. The effect of the 14 MeV neutrons on fast neutron activation analysis with D-D neutron generators is evaluated. (orig.)

Results of comparative RBMK neutron computation using VNIIEF codes (cell computation, 3D statics, 3D kinetics). Final report

Energy Technology Data Exchange (ETDEWEB)

Grebennikov, A.N.; Zhitnik, A.K.; Zvenigorodskaya, O.A. [and others

1995-12-31

In conformity with the protocol of the Workshop under Contract {open_quotes}Assessment of RBMK reactor safety using modern Western Codes{close_quotes} VNIIEF performed a neutronics computation series to compare western and VNIIEF codes and assess whether VNIIEF codes are suitable for RBMK type reactor safety assessment computation. The work was carried out in close collaboration with M.I. Rozhdestvensky and L.M. Podlazov, NIKIET employees. The effort involved: (1) cell computations with the WIMS, EKRAN codes (improved modification of the LOMA code) and the S-90 code (VNIIEF Monte Carlo). Cell, polycell, burnup computation; (2) 3D computation of static states with the KORAT-3D and NEU codes and comparison with results of computation with the NESTLE code (USA). The computations were performed in the geometry and using the neutron constants presented by the American party; (3) 3D computation of neutron kinetics with the KORAT-3D and NEU codes. These computations were performed in two formulations, both being developed in collaboration with NIKIET. Formulation of the first problem maximally possibly agrees with one of NESTLE problems and imitates gas bubble travel through a core. The second problem is a model of the RBMK as a whole with imitation of control and protection system controls (CPS) movement in a core.

Determination of the mean free path of the thermal neutrons transport by the measure of a complex diffusion length; Determination du libre parcours moyen de transport des neutrons thermiques par la mesure d'une longueur de diffusion complexe

Energy Technology Data Exchange (ETDEWEB)

Raievski, V; Horowitz, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1955-07-01

The further method is the outcome of a technique used in the study of neutrons in scattering and slowing-down environment. In this technique, we replace the constant sources used in the classic experiences by modulated sources with a variable frequency. The object of this article is to describe the extension of the method for the mean free path for transport of thermal neutrons and also to indicate the possible applications for other sizes, as the slowing length, or the absolute value of the cross-section of the boron. (M.B.) [French] La methode qui va etre decrite est l'aboutissement d'une technique utilisee dans l'etude des milieux ou diffusent et se ralentissent des neutrons. Dans cette technique, on remplace les sources constantes utilisees dans les experiences classiques par des sources modulees, a frequence variable. L'objet de cet article est de decrire l'extension de la methode a la mesure du libre parcours moyen de transport des neutrons thermiques et egalement d'indiquer les applications possibles a la mesure d'autres grandeurs, telles que la longueur de ralentissement, ou la valeur absolue de la section de capture du bore. (M.B.)

Interpretation of the quasi-elastic neutron scattering on PAA by rotational diffusion models

International Nuclear Information System (INIS)

Bata, L.; Vizi, J.; Kugler, S.

1974-10-01

First the most important data determined by other methods for para azoxy anisolon (PAA) are collected. This molecule makes a rotational oscillational motion around the mean molecular direction. The details of this motion can be determined by inelastic neutron scattering. Quasielastic neutron scattering measurements were carried out without orienting magnetic field on a time-of-flight facility with neutron beam of 4.26 meV. For the interpretation of the results two models, the spherical rotation diffusion model and the circular random walk model are investigated. The comparison shows that the circular random walk model (with N=8 sites, d=4A diameter and K=10 10 s -1 rate constant) fits very well with the quasi-elastic neutron scattering, while the spherical rotational diffusion model seems to be incorrect. (Sz.N.Z.)

Thermal neutron diffusion parameters in homogeneous mixtures

Energy Technology Data Exchange (ETDEWEB)

Drozdowicz, K.; Krynicka, E. [Institute of Nuclear Physics, Cracow (Poland)

1995-12-31

A physical background is presented for a computer program which calculates the thermal neutron diffusion parameters for homogeneous mixtures of any compounds. The macroscopic absorption, scattering and transport cross section of the mixture are defined which are generally function of the incident neutron energy. The energy-averaged neutron parameters are available when these energy dependences and the thermal neutron energy distribution are assumed. Then the averaged diffusion coefficient and the pulsed thermal neutron parameters (the absorption rare and the diffusion constant) are also defined. The absorption cross section is described by the 1/v law and deviations from this behaviour are considered. The scattering cross section can be assumed as being almost constant in the thermal neutron region (which results from the free gas model). Serious deviations are observed for hydrogen atoms bound in molecules and a special study in the paper is devoted to this problem. A certain effective scattering cross section is found in this case on a base of individual exact data for a few hydrogenous media. Approximations assumed for the average cosine of the scattering angle are also discussed. The macroscopic parameters calculated are averaged over the Maxwellian energy distribution for the thermal neutron flux. An information on the input data for the computer program is included. (author). 10 refs, 4 figs, 5 tabs.

Thermal neutron diffusion parameters in homogeneous mixtures

International Nuclear Information System (INIS)

Drozdowicz, K.; Krynicka, E.

1995-01-01

A physical background is presented for a computer program which calculates the thermal neutron diffusion parameters for homogeneous mixtures of any compounds. The macroscopic absorption, scattering and transport cross section of the mixture are defined which are generally function of the incident neutron energy. The energy-averaged neutron parameters are available when these energy dependences and the thermal neutron energy distribution are assumed. Then the averaged diffusion coefficient and the pulsed thermal neutron parameters (the absorption rare and the diffusion constant) are also defined. The absorption cross section is described by the 1/v law and deviations from this behaviour are considered. The scattering cross section can be assumed as being almost constant in the thermal neutron region (which results from the free gas model). Serious deviations are observed for hydrogen atoms bound in molecules and a special study in the paper is devoted to this problem. A certain effective scattering cross section is found in this case on a base of individual exact data for a few hydrogenous media. Approximations assumed for the average cosine of the scattering angle are also discussed. The macroscopic parameters calculated are averaged over the Maxwellian energy distribution for the thermal neutron flux. An information on the input data for the computer program is included. (author). 10 refs, 4 figs, 5 tabs

Stability and accuracy of 3D neutron transport simulations using the 2D/1D method in MPACT

International Nuclear Information System (INIS)

Collins, Benjamin; Stimpson, Shane; Kelley, Blake W.; Young, Mitchell T.H.; Kochunas, Brendan; Graham, Aaron; Larsen, Edward W.; Downar, Thomas; Godfrey, Andrew

2016-01-01

A consistent “2D/1D” neutron transport method is derived from the 3D Boltzmann transport equation, to calculate fuel-pin-resolved neutron fluxes for realistic full-core Pressurized Water Reactor (PWR) problems. The 2D/1D method employs the Method of Characteristics to discretize the radial variables and a lower order transport solution to discretize the axial variable. This paper describes the theory of the 2D/1D method and its implementation in the MPACT code, which has become the whole-core deterministic neutron transport solver for the Consortium for Advanced Simulations of Light Water Reactors (CASL) core simulator VERA-CS. Several applications have been performed on both leadership-class and industry-class computing clusters. Results are presented for whole-core solutions of the Watts Bar Nuclear Power Station Unit 1 and compared to both continuous-energy Monte Carlo results and plant data.

Stability and accuracy of 3D neutron transport simulations using the 2D/1D method in MPACT

Energy Technology Data Exchange (ETDEWEB)

Collins, Benjamin, E-mail: collinsbs@ornl.gov [Oak Ridge National Laboratory, One Bethel Valley Rd., Oak Ridge, TN 37831 (United States); Stimpson, Shane, E-mail: stimpsonsg@ornl.gov [Oak Ridge National Laboratory, One Bethel Valley Rd., Oak Ridge, TN 37831 (United States); Kelley, Blake W., E-mail: kelleybl@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Young, Mitchell T.H., E-mail: youngmit@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Kochunas, Brendan, E-mail: bkochuna@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Graham, Aaron, E-mail: aarograh@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Larsen, Edward W., E-mail: edlarsen@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Downar, Thomas, E-mail: downar@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Godfrey, Andrew, E-mail: godfreyat@ornl.gov [Oak Ridge National Laboratory, One Bethel Valley Rd., Oak Ridge, TN 37831 (United States)

2016-12-01

A consistent “2D/1D” neutron transport method is derived from the 3D Boltzmann transport equation, to calculate fuel-pin-resolved neutron fluxes for realistic full-core Pressurized Water Reactor (PWR) problems. The 2D/1D method employs the Method of Characteristics to discretize the radial variables and a lower order transport solution to discretize the axial variable. This paper describes the theory of the 2D/1D method and its implementation in the MPACT code, which has become the whole-core deterministic neutron transport solver for the Consortium for Advanced Simulations of Light Water Reactors (CASL) core simulator VERA-CS. Several applications have been performed on both leadership-class and industry-class computing clusters. Results are presented for whole-core solutions of the Watts Bar Nuclear Power Station Unit 1 and compared to both continuous-energy Monte Carlo results and plant data.

D-3He fuel cycles for neutron lean reactors

International Nuclear Information System (INIS)

Kernbichler, W.; Miley, G.H.; Heindler, M.

1989-01-01

The intrinsic potential of D-3He as a reactor fuel is investigated for a large range of 3He to D density ratios. A steady-state zero-dimensional reactor model is developed in which much care is attributed to a proper treatment of fast fusion products. Useful ranges of reactor parameters as well as temperature-density windows for driven and ignited operation are identified. Various figures of merit are calculated, such as power densities, net power production, neutron production, tritium load and radiative power. These results suggest several optimistic conclusions about the performance of D-3He as a reactor fuel

Numerical analysis for multi-group neutron-diffusion equation using Radial Point Interpolation Method (RPIM)

International Nuclear Information System (INIS)

Kim, Kyung-O; Jeong, Hae Sun; Jo, Daeseong

2017-01-01

Highlights: • Employing the Radial Point Interpolation Method (RPIM) in numerical analysis of multi-group neutron-diffusion equation. • Establishing mathematical formation of modified multi-group neutron-diffusion equation by RPIM. • Performing the numerical analysis for 2D critical problem. - Abstract: A mesh-free method is introduced to overcome the drawbacks (e.g., mesh generation and connectivity definition between the meshes) of mesh-based (nodal) methods such as the finite-element method and finite-difference method. In particular, the Point Interpolation Method (PIM) using a radial basis function is employed in the numerical analysis for the multi-group neutron-diffusion equation. The benchmark calculations are performed for the 2D homogeneous and heterogeneous problems, and the Multiquadrics (MQ) and Gaussian (EXP) functions are employed to analyze the effect of the radial basis function on the numerical solution. Additionally, the effect of the dimensionless shape parameter in those functions on the calculation accuracy is evaluated. According to the results, the radial PIM (RPIM) can provide a highly accurate solution for the multiplication eigenvalue and the neutron flux distribution, and the numerical solution with the MQ radial basis function exhibits the stable accuracy with respect to the reference solutions compared with the other solution. The dimensionless shape parameter directly affects the calculation accuracy and computing time. Values between 1.87 and 3.0 for the benchmark problems considered in this study lead to the most accurate solution. The difference between the analytical and numerical results for the neutron flux is significantly increased in the edge of the problem geometry, even though the maximum difference is lower than 4%. This phenomenon seems to arise from the derivative boundary condition at (x,0) and (0,y) positions, and it may be necessary to introduce additional strategy (e.g., the method using fictitious points and

Measurement of the diffusion length of thermal neutrons in the beryllium oxide

International Nuclear Information System (INIS)

Koechlin, J.C.; Martelly, J.; Duggal, V.P.

1955-01-01

The diffusion length of thermal neutrons in the beryllium oxide has been obtained while studying the spatial distribution of the neutrons in a massive parallelepiped of this matter placed before the thermal column of the reactor core of Saclay. The mean density of the beryllium oxide (BeO) is 2,95 gr/cm 3 , the mean density of the massif is 2,92 gr/cm 3 . The value of the diffusion length, deducted of the done measures, is: L = 32,7 ± 0,5 cm (likely gap). Some remarks are formulated about the influence of the spectral distribution of the neutrons flux used. (authors) [fr

Conception of a target diffusible Pt. 3

International Nuclear Information System (INIS)

Peters, J.M.

1980-01-01

A new manufacturing self-replenishing target has been tested for the regeneration of deuteride titanium (γ) phase followed by the study of its behaviour under deuteron beam in the production of neutrons by the D(d,n) 3 He reaction. An interpretation of the self-replenishing mechanism is attempted here, based on diffusion and flow rate measurements through the target (Pd-Ag) (70%-30%), 0.5 mm of thickness, - Ti layer (522 μg cm -2 ). A general formula is proposed to describe the flow rate variations during the regeneration experiences. (author)

Derivation of a volume-averaged neutron diffusion equation; Atomos para el desarrollo de Mexico

Energy Technology Data Exchange (ETDEWEB)

Vazquez R, R.; Espinosa P, G. [UAM-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, Mexico D.F. 09340 (Mexico); Morales S, Jaime B. [UNAM, Laboratorio de Analisis en Ingenieria de Reactores Nucleares, Paseo Cuauhnahuac 8532, Jiutepec, Morelos 62550 (Mexico)]. e-mail: rvr@xanum.uam.mx

2008-07-01

This paper presents a general theoretical analysis of the problem of neutron motion in a nuclear reactor, where large variations on neutron cross sections normally preclude the use of the classical neutron diffusion equation. A volume-averaged neutron diffusion equation is derived which includes correction terms to diffusion and nuclear reaction effects. A method is presented to determine closure-relationships for the volume-averaged neutron diffusion equation (e.g., effective neutron diffusivity). In order to describe the distribution of neutrons in a highly heterogeneous configuration, it was necessary to extend the classical neutron diffusion equation. Thus, the volume averaged diffusion equation include two corrections factor: the first correction is related with the absorption process of the neutron and the second correction is a contribution to the neutron diffusion, both parameters are related to neutron effects on the interface of a heterogeneous configuration. (Author)

Total cross-section measurements on aluminium, carbon, fluorine and hydrogen for d, d reaction neutrons using the coincidence method (1963); Mesure de la section efficace totale de l'aluminium, du carbone, du fluor et de l'hydrogene pour des neutrons de la reaction d, d par la methode des coincidences (1963)

Energy Technology Data Exchange (ETDEWEB)

Ambrosino, G; Sorriaux, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

The experiment described consists in the measurement of the total cross-section of various materials: aluminium, carbon, fluorine and hydrogen, for mono-energetic 2.77 MeV neutrons obtained from the d,d reaction. The measurement is carried out by transmission. The neutrons are detected by means of a plastic scintillator mounted on a 56 AVP photomultiplier, and are isolated from all secondary phenomena (background noise, scattered neutrons) by coincidence with helium 3. which particles are associated to the neutrons from the reaction {sup 2}{sub 1}D ({sup 2}{sub 1}D, n) {sup 3}{sub 2}H The helium 3 particles are detected by a PN junction diode used with inverted polarisation. An absorption exponential has been traced out using measurements made on seven aluminium bars. The accuracy of the total cross-section measurements is about 10{sup -2}. (authors) [French] L'experience exposee dans ce rapport consiste en la mesure des sections efficaces totales de differents materiaux: aluminium, carbone, fluor et hydrogene, pour des neutrons monoenergetiques de 2,77 MeV, obtenus par la reaction d,d. La mesure est faite par transmission. Les neutrons sont detectes par un scintillateur plastique monte sur un photomultiplicateur 56 AVP, et sont separes de tout phenomene secondaire (bruit de fond, neutrons diffuses) par coincidence avec les helium 3, particules associees aux neutrons de la reaction {sup 2}{sub 1}D ({sup 2}{sub 1}D, n) {sup 3}{sub 2}H Les helium 3 sont detectes par une diode a jonction PN utilisee en polarisation inverse. Une exponentielle d'absorption a ete tracee a partir de mesures faites sur sept barreaux d'aluminium. La precision des mesures des sections efficaces totales est de l'ordre de 10{sup -2}. (auteurs)

Gender difference of serum angiotensin-converting enzyme (ACE) activity in DD genotype of ACE insertion/deletion polymorphism in elderly Chinese.

Science.gov (United States)

Zhang, Ya-Feng; Cheng, Qiong; Tang, Nelson L S; Chu, Tanya T W; Tomlinson, Brian; Liu, Fan; Kwok, Timothy C Y

2014-12-01

In this study we investigated the gender difference of serum angiotensin-converting enzyme (ACE) activity in a population of Hong Kong-dwelling elderly Chinese. A total of 1767 (843 male, 924 female) Hong Kong-dwelling elderly Chinese were recruited. ACE I/D genotypes were identified by polymerase chain reaction amplification and serum ACE activity was determined using a commercially available kinetic kit. ACE I/D genotype distribution was compared by chi-square test, the correlation between ACE I/D polymorphism and serum ACE activity was analysed by ANOVA test and gender difference of serum ACE activity of different genotypes was compared by independent sample t-test. No statistically significant difference of genotype distribution between male and female subjects was found. Serum ACE activity was significantly correlated with ACE genotype. Overall, there was no gender difference of serum ACE activity; however, when sub-grouping the subjects by ACE I/D genotype, male subjects with DD genotype had higher serum ACE activity than female subjects with DD genotype. No significant gender difference of genotype distribution was found in elderly Chinese. Serum ACE activity was significantly correlated with ACE I/D polymorphism in elderly Chinese. Male subjects with DD genotype had higher serum ACE activity than female subjects with DD genotype. © The Author(s) 2013.

Experiment of Neutron Generation by Using Prototype D-D Neutron Generator

International Nuclear Information System (INIS)

Kim, In Jung; Kim, Suk Kwon; Park, Chang Su; Jung, Nam Suk; Jung, Hwa Dong; Park, Ji Young; Hwang, Yong Seok; Choi, H.D.

2005-01-01

Experiment of neutron generation was performed by using a prototype D-D neutron generator. The characteristics of D-D neutron generation in drive-in target was studied. The increment of neutron yield by increasing ion beam energy was investigated, too

A 2D/1D coupling neutron transport method based on the matrix MOC and NEM methods

International Nuclear Information System (INIS)

Zhang, H.; Zheng, Y.; Wu, H.; Cao, L.

2013-01-01

A new 2D/1D coupling method based on the matrix MOC method (MMOC) and nodal expansion method (NEM) is proposed for solving the three-dimensional heterogeneous neutron transport problem. The MMOC method, used for radial two-dimensional calculation, constructs a response matrix between source and flux with only one sweep and then solves the linear system by using the restarted GMRES algorithm instead of the traditional trajectory sweeping process during within-group iteration for angular flux update. Long characteristics are generated by using the customization of commercial software AutoCAD. A one-dimensional diffusion calculation is carried out in the axial direction by employing the NEM method. The 2D and ID solutions are coupled through the transverse leakage items. The 3D CMFD method is used to ensure the global neutron balance and adjust the different convergence properties of the radial and axial solvers. A computational code is developed based on these theories. Two benchmarks are calculated to verify the coupling method and the code. It is observed that the corresponding numerical results agree well with references, which indicates that the new method is capable of solving the 3D heterogeneous neutron transport problem directly. (authors)

A 2D/1D coupling neutron transport method based on the matrix MOC and NEM methods

Energy Technology Data Exchange (ETDEWEB)

Zhang, H.; Zheng, Y.; Wu, H.; Cao, L. [School of Nuclear Science and Technology, Xi' an Jiaotong University, No. 28, Xianning West Road, Xi' an, Shaanxi 710049 (China)

2013-07-01

A new 2D/1D coupling method based on the matrix MOC method (MMOC) and nodal expansion method (NEM) is proposed for solving the three-dimensional heterogeneous neutron transport problem. The MMOC method, used for radial two-dimensional calculation, constructs a response matrix between source and flux with only one sweep and then solves the linear system by using the restarted GMRES algorithm instead of the traditional trajectory sweeping process during within-group iteration for angular flux update. Long characteristics are generated by using the customization of commercial software AutoCAD. A one-dimensional diffusion calculation is carried out in the axial direction by employing the NEM method. The 2D and ID solutions are coupled through the transverse leakage items. The 3D CMFD method is used to ensure the global neutron balance and adjust the different convergence properties of the radial and axial solvers. A computational code is developed based on these theories. Two benchmarks are calculated to verify the coupling method and the code. It is observed that the corresponding numerical results agree well with references, which indicates that the new method is capable of solving the 3D heterogeneous neutron transport problem directly. (authors)

Fast neutron irradiation effects on diffusion processes in the aluminum-magnesium system; Effets de l'irradiation aux neutrons rapides sur les phenomenes lies a la diffusion dans le systeme aluminium-magnesium

Energy Technology Data Exchange (ETDEWEB)

Moreau, G [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1969-06-01

Examination of bulky diffusion couples Al (Mg) - Al and Mg (Al) - Mg handled in same thermal conditions (between 200 and 440 C) out of pile and under fast neutron irradiation show, in the latter case: 1 - An increase of the growth kinetics of {beta} phase which can be explained with KIDSON' s formula. 2 - An apparent increase of solubility caused by migration of a part of excess vacancies as complexes (vacancy - solute atom) to sinks (stacking faults, grain boundaries) or to sub-microscopical clusters. 3 - An enhancement of chemical diffusion at low temperature. At infinite dilution, chemical diffusion coefficient of Mg in Al can be expressed in normal conditions as: D = 1 exp(- 31000/RT {+-} 1200/RT cal/mole) cm{sup 2}.s{sup -1} and under irradiation as: D = 8.10{sup -3} exp(-24500/RT {+-} 1200/RT cal/mole) cm{sup 2}.s{sup -1}. Interpretation can be carried out by DIENES and Damask's theory. Excess defects (vacancies and interstitials generated in equal numbers by radiation) annihilate by migration to sinks and by direct recombination. Sinks density varies with temperature and irradiation time. The part of complexes (vacancy-solute atom) is important in the vacancies annealing kinetics. (author) [French] L'examen de couples de diffusion massifs Al (Mg) - Al et Mg (Al) - Mg traites dans les memes conditions thermiques (entre 200 et 440 C) hors pile et sous flux de neutrons rapides montre dans le dernier cas: 1 - Une acceleration de la cinetique de croissance de la phase {beta} a basse temperature dont on peut rendre compte a l'aide de la formule de KIDSON. 2 - Une augmentation apparente de la solubilite due a l'elimination d'une partie des lacunes en exces sous forme de complexes (lacune -solute) sur des pieges (dislocations, joints) ou sous forme d'amas sub-microscopiques. 3 - Une acceleration de la diffusion a basse temperature. A dilution infinie la diffusion (en cm{sup 2}/s) du Mg dans l'Al passe de: 1 exp(- 31000/RT {+-} 1200/RT cal/mole) a 8.10{sup -3} exp

A Cold Neutron Monochromator and Scattering Apparatus; Monochromateur et appareillage pour la diffusion de neutrons lents; Monokhromator dlya ''kholodnykh'' nejtronov i pribor dlya rasseyaniya; Monocromador y aparato de dispersion para neutrones frios

Energy Technology Data Exchange (ETDEWEB)

Harris, D; Cocking, S J; Egelstaff, P A; Webb, F J [Nuclear Physics Division, Aere, Harwell, Didcot, Berks (United Kingdom)

1963-01-15

A narrow band of neutron wavelengths (4 A and greater) is selected from a collimated neutron beam obtained from the Dido reactor at Harwell. These neutrqps are scattered by various samples and the energy transfer of the scattered neutrons measured using time-of-flight techniques. The neutrons, moderated by a liquid hydrogen source in the reactor pass through first a liquid nitrogen- cooled filter, then a single crystal of bismuth and finally they are ''chopped'' by a magnesium-cadmium high- speed curved slot rotor. In this apparatus the wavelength spread of 0. 3 A at 4 . 1 A is determined primarily by the Be-Bi filter, while the time spread (8 {mu}s) is determined by the rotor. The monochromated neutron bursts from this rotor are scattered by a sample and detected in one of two counter arrays. When studying liquid or polycrystalline samples an array of six BF{sub 3}, counter assemblies (each 2 inches x 24 inches in area)are used covering scatter angles from 20{sup o} to 90{sup o}. This array is placed below the neutron beam. Above the line of the neutron beam is a second array consisting of three scintillators 2 inches in diameter, which is used for the study of single crystal samples. The output of each counter is fed into a tape recording system which has 500 time channels available for each counter. This apparatus has been used to study neutron scattering from several gaseous, liquid and crystalline samples and the most recent measurements are presented in other papers in these proceedings. [French] Les auteurs extraient une bande etroite de neutrons ( 4 A et plus) d'un faisceau collimate de neutrons produits par le reacteur Dido de Harwell. On fait diffuser ces neutrons au moyen de divers echantillons et on mesure le transfert d'energie des neutrons diffuses par la methode du temps de vol. Les neutrons ralentis par de l'hydrogene liquide place dans le reacteur passent d'abord dans un filtre refroidi a l'azote liquide, puis dans un monocristal de bismuth

Measurement of Diffusion Parameters and of Anisotropy of Graphite with a Pulsed Source of Neutrons; Mesure des parametres de diffusion et de l'anisotropie du graphite a l'aide d'une source pulsee de neutrons

Energy Technology Data Exchange (ETDEWEB)

Sagot, M; Tellier, H [Commissariat a l' Energie Atomique. Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)

1963-07-01

The diffusion coefficient, cooling coefficient, and anisotropy of graphite were determined to be (2.19 {+-} 0.03) x 10{sup 5} cm{sup 2} sec{sup -1}, (37.9 {+-} 4) x 10{sup 5} cm{sup 4} sec{sup -1}, and 1.017 {+-} 0.008, respectively. The range of geometrical buckling was from 7 to 155 m{sup -2}. The values obtained are compared with published values. (authors) [French] Un programme experimental utilisant la methode de la source pulsee de neutrons a ete realise sur le graphite. La gamme des laplaciens couverte est de 7 m{sup -2} a 155 m{sup -2}. Les resultats en sont presentes dans ce rapport: - coefficient de diffusion D{sub 0} = (2,19 {+-} 0,03) x 10{sup 5} cm{sup 2} s{sup -1} - coefficient de refroidissement C = (37,9 {+-} 4) x 10{sup 5} cm{sup 4} s{sup -1} - anisotropie du graphite (D parall./D perp.) = 1,017 {+-} 0,008. Ils sont compares aux valeurs deja publiees. (auteurs)

Relevance of d-D interactions on neutron and tritium production in IFMIF-EVEDA accelerator prototype

International Nuclear Information System (INIS)

Mayoral, A.; Sanz, J.; Sauvan, P.; Lopez, D.; Garcia, M.; Ogando, F.

2011-01-01

In the IFMIF-EVEDA accelerator prototype, deuterium is implanted in the components due to beam losses and in the beam dump, where the beam is stopped. The interaction of the deuterons with the deuterium previously implanted leads to the production of neutrons and tritium, which are important issues for radioprotection and safety analysis. A methodology to assess these production pathways in more realistic approach has been developed. The new tools and their main achievement are: (i) an 'effective diffusivity coefficient' (deduced from available experimental data) that enables simulation of the diffusion phase, and (ii) the MCUNED code (able to handle deuteron transport libraries) allows to simulate the transport-slowdown of deuteron/tritium (to get the concentration profiles) and the neutron/tritium productions from d-Cu and d-D for up to 9 MeV incident deuteron. The results with/without theses tools are presented and their effect on the relevance of d-D sources versus d-Cu is evaluated.

Hydrogen diffusion in the storage compound Ti sub(0.8) Zr sub(0.2)CrMnH3 studied by neutron scattering

International Nuclear Information System (INIS)

Pugliesi, R.

1983-01-01

The hydrogen diffusion in the storage material Ti sub(0.8) Zr sub(0.2)CrMnH 3 has been studied in the temperature range of 260 to 360K, by means of the quasi-elastic neutron scattering technique. The experimental measurements have been performed using a high resolution backscattering spectrometer. The half widths at half maximum of the quasi-elastic line have been determined for momentum transfers in the range 0.24 to 1.85 A -1 . The data, corrected for multiple scattering effect, have been analysed in term of simple diffusion and jump diffusion models. From the diffusion coefficients determined at different temperatures, the following Arrhenius equation was obtained: D= (3+-1) x 10 -8 m 2 /s exp [-(220+-20 meV/kT] yielding a diffusion coefficient at room temperature of 6.0 x 10 -12 m 2 /s. This comparatively fast hydrogen diffusion is not the rate determining step in the absorption and desorption kinetics. The results at large momentum transfers show evidence for the existence of more than one component in the quasi-elastic spectra. This fact has been explained considering the diffusion governed by the existence of energetically different interstitial sites and by blocking effects due to the high hydrogen concentration. (Author) [pt

SNAP - a three dimensional neutron diffusion code

International Nuclear Information System (INIS)

McCallien, C.W.J.

1993-02-01

This report describes a one- two- three-dimensional multi-group diffusion code, SNAP, which is primarily intended for neutron diffusion calculations but can also carry out gamma calculations if the diffusion approximation is accurate enough. It is suitable for fast and thermal reactor core calculations and for shield calculations. SNAP can solve the multi-group neutron diffusion equations using finite difference methods. The one-dimensional slab, cylindrical and spherical geometries and the two-dimensional case are all treated as simple special cases of three-dimensional geometries. Numerous reflective and periodic symmetry options are available and may be used to reduce the number of mesh points necessary to represent the system. Extrapolation lengths can be specified at internal and external boundaries. (Author)

Neutron spin-echo spectroscopy for diffusion in crystalline solids

International Nuclear Information System (INIS)

Kaisermayr, M.; Rennhofer, M.; Vogl, G.; Pappas, C.; Longeville, S.

2002-01-01

Neutron spin-echo spectroscopy (NSE) offers unprecedented opportunities in the investigation of diffusion in crystalline systems due to its outstanding energy resolution. NSE not only enables measurements at lower diffusivities than the established techniques of neutron spectroscopy, but it also gives a very immediate access to the different time scales involved in the diffusion process. This is demonstrated in detail on the example of the binary alloy NiGa where the Ni atoms hop between regular sites on the Ni sublattice and anti-sites on the Ga sublattice. Experiments on two different NSE instruments are compared to measurements using neutron backscattering spectroscopy. The potential of NSE for the investigation of jump diffusion and experimental requirements are discussed

The angiotensin-converting enzyme (ACE) gene insertion/ deletion dimorphism tracks with higher serum ace activities in both younger and older subjects

International Nuclear Information System (INIS)

Frossard, Philippe M.; Hill, Susan H.; Obineche, Enyioma N.; Lestringant, Gilles G.

1998-01-01

The absence of a 287 base pair alu sequence in the ACE gene (D allele) is associated with higher ACE levels than its presence (I allele) in adults. We carried out a case control study of thr ACE*I/D dimorphism in relation to circulating ACE activities to evaluate associations between the two variables in adults, compared to younger (18 years or less) individuals. Genotypes of the ACE*I/D dimorphism were determined on DNA samples from a population of 164 random (unrelated) Emirtaes nationals, composed of groups: 112 subjects above 18 years of age (range=20-77), and 52 subjects of 18 years or less (range=1-18) and analyzed for putative associations with serum ACE activities. ACE*I/D genotypes of the 164 individualds were determined by assays based on polymerase chain reaction. ACE activities were determined on serum samples of these subjects bu colorimetric assays. The D allele was associared with increasd ACE values in both adult and younger individuals. Mean ACE activity levels associated with II, ID and DD genotypes, however, were 42%-61% higher in the 18 years and under group of subjects. The ACE*I/D marker accounted for 28% of the variance of the phenomenon determining ACE levels in adults, and for 30% among youngsters. The ACE*I/D dimorphism is correlated strongly with circulating ACE activities in both and young Emirati, subjects and the corresponding mean ACE activities were significantly higher among the youngsters. (author)

Measurement of the diffusion length of thermal neutrons inside graphite

International Nuclear Information System (INIS)

Ertaud, A.; Beauge, R.; Fauquez, H.; De Laboulay, H.; Mercier, C.; Vautrey, L.

1948-11-01

The diffusion length of thermal neutrons inside a given industrial graphite is determined by measuring the neutron density inside a parallelepipedal piling up of graphite bricks (2.10 x 2.10 x 2.442 m). A 3.8 curies (Ra α → Be) source is placed inside the parallelepipedal block of graphite and thin manganese detectors are used. Corrections are added to the unweighted measurements to take into account the effects of the damping of supra-thermal neutrons in the measurement area. These corrections are experimentally deduced from the differential measurements made with a cadmium screen interposed between the source and the first plane of measurement. An error analysis completes the report. The diffusion length obtained is: L = 45.7 cm ± 0.3. The average density of the graphite used is 1.76 and the average apparent density of the piling up is 1.71. (J.S.)

Development of neutron diffuse scattering analysis code by thin film and multilayer film

International Nuclear Information System (INIS)

Soyama, Kazuhiko

2004-01-01

To research surface structure of thin film and multilayer film by neutron, a neutron diffuse scattering analysis code using DWBA (Distorted-Wave Bron Approximation) principle was developed. Subjects using this code contain the surface and interface properties of solid/solid, solid/liquid, liquid/liquid and gas/liquid, and metal, magnetism and polymer thin film and biomembran. The roughness of surface and interface of substance shows fractal self-similarity and its analytical model is based on DWBA theory by Sinha. The surface and interface properties by diffuse scattering are investigated on the basis of the theoretical model. The calculation values are proved to be agreed with the experimental values. On neutron diffuse scattering by thin film, roughness of surface of thin film, correlation function, neutron propagation by thin film, diffuse scattering by DWBA theory, measurement model, SDIFFF (neutron diffuse scattering analysis program by thin film) and simulation results are explained. On neutron diffuse scattering by multilayer film, roughness of multilayer film, principle of diffuse scattering, measurement method and simulation examples by MDIFF (neutron diffuse scattering analysis program by multilayer film) are explained. (S.Y.)To research surface structure of thin film and multilayer film by neutron, a neutron diffuse scattering analysis code using DWBA (Distorted-Wave Bron Approximation) principle was developed. Subjects using this code contain the surface and interface properties of solid/solid, solid/liquid, liquid/liquid and gas/liquid, and metal, magnetism and polymer thin film and biomembran. The roughness of surface and interface of substance shows fractal self-similarity and its analytical model is based on DWBA theory by Sinha. The surface and interface properties by diffuse scattering are investigated on the basis of the theoretical model. The calculation values are proved to be agreed with the experimental values. On neutron diffuse scattering

Insertion/deletion polymorphism of the ACE gene and adherence to ACE inhibitors

NARCIS (Netherlands)

H. Schelleman (Hedi); O.H. Klungel (Olaf); C.M. van Duijn (Cornelia); J.C.M. Witteman (Jacqueline); A. Hofman (Albert); A.C. de Boer (Anton); B.H.Ch. Stricker (Bruno)

2005-01-01

textabstractAims: We investigated whether the insertion/deletion (I/D) polymorphism of the ACE gene modified the adherence to ACE inhibitors as measured by the discontinuation of an ACE inhibitor, or addition of another antihypertensive drug. Methods: This was a cohort study among 239 subjects who

New Multi-group Transport Neutronics (PHISICS) Capabilities for RELAP5-3D and its Application to Phase I of the OECD/NEA MHTGR-350 MW Benchmark

Energy Technology Data Exchange (ETDEWEB)

Gerhard Strydom; Cristian Rabiti; Andrea Alfonsi

2012-10-01

PHISICS is a neutronics code system currently under development at the Idaho National Laboratory (INL). Its goal is to provide state of the art simulation capability to reactor designers. The different modules for PHISICS currently under development are a nodal and semi-structured transport core solver (INSTANT), a depletion module (MRTAU) and a cross section interpolation (MIXER) module. The INSTANT module is the most developed of the mentioned above. Basic functionalities are ready to use, but the code is still in continuous development to extend its capabilities. This paper reports on the effort of coupling the nodal kinetics code package PHISICS (INSTANT/MRTAU/MIXER) to the thermal hydraulics system code RELAP5-3D, to enable full core and system modeling. This will enable the possibility to model coupled (thermal-hydraulics and neutronics) problems with more options for 3D neutron kinetics, compared to the existing diffusion theory neutron kinetics module in RELAP5-3D (NESTLE). In the second part of the paper, an overview of the OECD/NEA MHTGR-350 MW benchmark is given. This benchmark has been approved by the OECD, and is based on the General Atomics 350 MW Modular High Temperature Gas Reactor (MHTGR) design. The benchmark includes coupled neutronics thermal hydraulics exercises that require more capabilities than RELAP5-3D with NESTLE offers. Therefore, the MHTGR benchmark makes extensive use of the new PHISICS/RELAP5-3D coupling capabilities. The paper presents the preliminary results of the three steady state exercises specified in Phase I of the benchmark using PHISICS/RELAP5-3D.

Development of a compact D-D neutron generator

Science.gov (United States)

Huang, Z.-W.; Wang, J.-R.; Wei, Z.; Lu, X.-L.; Ma, Z.-W.; Ran, J.-L.; Zhang, Z.-M.; Yao, Z.-E.; Zhang, Y.

2018-01-01

A compact D-D neutron generator was developed at Lanzhou University, China. A duoplasmatron ion source was used to produce a higher-current deuteron beam. The deuteron beam could be accelerated up to 150 keV by a single accelerating gap, and bombarded on a pure molybdenum drive-in target to produce D-D fast neutron. A bias voltage between the target and the extraction-accelerating electrode was produced by a resistance to suppress the secondary electron from the target. The neutron generator has been operated for several hundred hours, and the performances were investigated. The available range of the deuteron beam current was 1.0-4.0 mA. EJ410 scintillator detector system was used to measure the fast neutron yields. D-D neutron yield could reach 2.48×108 n/s under the deuteron beam of 3 mA and 150 keV.

Hybrid Detectors for Neutrons Combining Phenyl- Polysiloxanes with 3D Silicon Detectors

International Nuclear Information System (INIS)

Dalla Palma, Matteo; Quaranta, Alberto; Collazuol, Gianmaria; Carturan, Sara; Cinausero, Marco; Gramegna, Fabiana; Marchi, Tommaso; Dalla Betta, Gian-Franco; Mendicino, Roberto; Povoli, Marco; Boscardin, Maurizio; Giacomini, Gabriele; Ronchin, Sabina; Zorzi, Nicola

2013-06-01

We report on the initial results of a research project aimed at the development hybrid detectors for fast neutrons by combining a phenyl-polysiloxane-based converter with a 3D silicon detector. To this purpose, new 3D sensor structures have been designed, fabricated and electrically tested, showing low depletion voltage and good leakage current. Moreover, the radiation detection capability of 3D sensors was tested by measuring the signals recorded from alpha particles, gamma rays, and pulsed lasers. The converter has been poured into the 3D cavities with excellent coupling, as confirmed by cross-section SEM analyses. Preliminary tests with neutrons have been carried out on the first hybrid detector prototypes at the CN accelerator of INFN LNL. The device design and technology are discussed, along with the first results from the electrical and functional characterization. (authors)

An extension of diffusion theory for thermal neutrons near boundaries

International Nuclear Information System (INIS)

Alvarez Rivas, J. L.

1963-01-01

The distribution of thermal neutron flux has been measured inside and outside copper rods of several diameters, immersed in water. It has been found that these distributions can be calculated by means of elemental diffusion theory if the value of the coefficient of diffusion is changed. this parameter is truly a diffusion coefficient, which now also depends on the diameter of the rod. Through a model an expression of this coefficient is introduced which takes account of the measurements of the author and of those reported in PIGC P/928 (1995), ANL-5872 (1959), DEGR 319 (D) (1961). This model could be extended also to plane geometry. (Author) 19 refs

Associations of ACE I/D, AGT M235T gene polymorphisms with pregnancy induced hypertension in Chinese population: a meta-analysis.

Science.gov (United States)

Zhu, Ming; Zhang, Jie; Nie, Shaofa; Yan, Weirong

2012-09-01

There have been many studies concerning the associations of angiotensin-converting enzyme (ACE) I/D, angiotensinogen (AGT) M235T polymorphisms with pregnancy induced hypertension (PIH) among Chinese populations. However, the results were inconsistent, prompting the necessity of meta-analysis. Studies published in English and Chinese were mainly searched in EMbase, PubMed and CBM up to January 2012. Twenty-three studies with 3,551 subjects for ACE I/D and seven studies with 1,296 subjects for AGT M235T were included. Significant associations were found between ACE I/D and PIH under dominant, recessive and allelic models. A separate analysis confined to preeclampsia suggested that ACE I/D was associated with preeclampsia under recessive model and allelic model, but not dominant model. Stratified analyses were conducted as meta-regression analysis indicated that the sample size of case group was a significant source of heterogeneity, which suggested no significant association between ACE I/D and PIH in the subgroup of more than 100 cases. Associations were found between AGT M235T and PIH under dominant genetic model (OR = 1.59; 95 %CI: 1.04-2.42), recessive genetic model (OR = 1.60; 95 %CI: 1.07-2.40), and allelic model (OR = 1.40; 95 %CI: 1.17-1.68). No publication bias was found in either meta-analysis. The present meta-analysis suggested significant associations between ACE I/D, AGT M235T and PIH in Chinese populations. However, no significant association was found between ACE I/D and PIH in the subgroup of more than 100 cases. Studies with larger sample sizes are necessary to investigate the associations between gene polymorphisms and PIH in Chinese populations.

Beneficial role of D allele in controlling ACE levels: a study among Brahmins of north India.

Science.gov (United States)

Kumari, Shobha; Sharma, Nidhi; Thakur, Sunil; Mondal, Prakash R; Saraswathy, Kallur N

2016-06-01

India being a country with vast diversity is expected to have different dietary and life style patterns which in turn may lead to population-specific environmental risk factors. Further, the interaction of these risk factors with the genetic makeup of population makes it either susceptible or resistant to cardiovascular disease. One such candidate gene is angiotensin converting enzyme (ACE) for various cardiovascular mechanisms. ACE is the key enzyme of the renin angiotensin aldosterone system pathway which maintains homeostasis blood pressure in the body and any variation in the levels is reported to be associated with various complex diseases. The DD genotype is found to increase ACE levels, which is associated with cardiovascular diseases and decrease in ACE levels are associated with kidney diseases. The aim of this study was to understand the distribution of ACE I/D polymorphism and ACE levels among Brahmins of National Capital Region (NCR) north India, with respect to age and sex ratio distribution. In this study, 136 subjects of which 50 males and 86 females, who were unrelated up to first cousin, aged 25 to70 years were studied. ACE gene was found to be polymorphic with high frequency of heterozygote (ID) followed by II and DD genotypes. The studied population was found to be in Hardy-Weinberg equilibrium with respect to ACE I/D polymorphism (P = 0.55). I allele frequency was found to be higher (0.560) than the D allele (0.44). The median level of ACE was found to be 65.96 ng/mL (48.12-86.24) which is towards lower side of the normal range. ACE levels were found to be increased among individual having either of the homozygotes that is II or DD and higher frequency of heterozygote (ID) is indicative of advantage in the population by maintaining lower ACE levels. The limitation of the present study is low sample size, however, the merit is that the subjects belonged to a Mendalian population with a common gene pool.

Associations of ACE Gene Insertion/Deletion Polymorphism, ACE Activity, and ACE mRNA Expression with Hypertension in a Chinese Population

OpenAIRE

He, Qingfang; Fan, Chunhong; Yu, Min; Wallar, Gina; Zhang, Zuo-Feng; Wang, Lixin; Zhang, Xinwei; Hu, Ruying

2013-01-01

Background The present study was designed to explore the association of angiotensin converting enzyme (ACE) gene insertion/deletion (I/D, rs4646994) polymorphism, plasma ACE activity, and circulating ACE mRNA expression with essential hypertension (EH) in a Chinese population. In addition, a new detection method for circulating ACE mRNA expression was explored. Methods The research was approved by the ethics committee of Zhejiang Provincial Center for Disease Prevention and Control. Written i...

Chemical order-disorder in alloys. Study by neutrons diffuse diffusion

International Nuclear Information System (INIS)

Novion, C. de; Beuneu, B.

1993-01-01

Applications of neutrons diffuse diffusion for short distance chemical order in FCC transition metals solid solutions (Pd-V, Ni-V, Ni-Cr) and understoichiometric carbides or nitrides of transition metals (TiC 1-x , NbC 1-x , TiN 1-x ) are shortly presented with theoretical and experimental aspects. (A.B.)

3D neutronic codes coupled with thermal-hydraulic system codes for PWR, and BWR and VVER reactors

Energy Technology Data Exchange (ETDEWEB)

Langenbuch, S.; Velkov, K. [GRS, Garching (Germany); Lizorkin, M. [Kurchatov-Institute, Moscow (Russian Federation)] [and others

1997-07-01

This paper describes the objectives of code development for coupling 3D neutronics codes with thermal-hydraulic system codes. The present status of coupling ATHLET with three 3D neutronics codes for VVER- and LWR-reactors is presented. After describing the basic features of the 3D neutronic codes BIPR-8 from Kurchatov-Institute, DYN3D from Research Center Rossendorf and QUABOX/CUBBOX from GRS, first applications of coupled codes for different transient and accident scenarios are presented. The need of further investigations is discussed.

Technology Development for 3-D Wide Swath Imaging Supporting ACE

Science.gov (United States)

Racette, Paul; Heymsfield, Gerry; Li, Lihua; Mclinden, Matthew; Park, Richard; Cooley, Michael; Stenger, Pete; Hand, Thomas

2014-01-01

The National Academy of Sciences Decadal Survey (DS) Aerosol-Cloud-Ecosystems Mission (ACE) aims to advance our ability to observe and predict changes to the Earth's hydrological cycle and energy balance in response to climate forcing, especially those changes associated with the effects of aerosol on clouds and precipitation. ACE is focused on obtaining measurements to reduce the uncertainties in current climate models arising from the lack in understanding of aerosol-cloud interactions. As part of the mission instrument suite, a dual-frequency radar comprised of a fixed-beam 94 gigahertz (W-band) radar and a wide-swath 35 gigahertz (Ka-band) imaging radar has been recommended by the ACE Science Working Group.In our 2010 Instrument Incubator Program project, we've developed a radar architecture that addresses the challenge associated with achieving the measurement objectives through an innovative, shared aperture antenna that allows dual-frequency radar operation while achieving wide-swath (100 kilometers) imaging at Ka-band. The antenna system incorporates 2 key technologies; a) a novel dual-band reflectorreflectarray and b) a Ka-band Active Electronically Scanned Array (AESA) feed module. The dual-band antenna is comprised of a primary cylindrical reflectorreflectarray surface illuminated by a point-focus W-band feed (compatible with a quasi-optical beam waveguide feed, such as that employed on CloudSat); the Ka-band AESA line feed provides wide-swath across-track scanning. The benefits of this shared-aperture approach include significant reductions in ACE satellite payload size, weight, and cost, as compared to a two aperture approach. Four objectives were addressed in our project. The first entailed developing the tools for the analysis and design of reflectarray antennas, assessment of candidate reflectarray elements, and validation using test coupons. The second objective was to develop a full-scale aperture design utilizing the reflectarray surface and to

Novel 3D silicon sensors for neutron detection

International Nuclear Information System (INIS)

Mendicino, R; Betta, G-F Dalla; Palma, M Dalla; Perillo, E; Povoli, M; Quaranta, A; Boscardin, M; Ronchin, S; Zorzi, N; Carturan, S; Cinausero, M; Gramegna, F; Marchi, T; , University of Padova, Via Marzolo 8, 35131 Padova (Italy))" data-affiliation=" (Department of Physics and Astronomy ''G.Galilei, University of Padova, Via Marzolo 8, 35131 Padova (Italy))" >Collazuol, G

2014-01-01

In this paper we report a novel 3D sensor structure to be used as a neutron detector in combination with an organic converter material based on polysiloxane. The first prototypes of the proposed device are presented, with emphasis on the experimental characterization. Selected results from the functional tests (with alpha particle source and pulsed laser scans) are discussed with the aid of TCAD simulations

Study of fast neutron scattering. The displacement cross-section (1962); Etude de la diffusion des neutrons rapides. Section efficace de deplacement (1962)

Energy Technology Data Exchange (ETDEWEB)

Millot, J P [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1962-07-01

We propose a method for calculating the biological efficiency of fast neutrons emitted by in-pile fission sources. This method justifies the empirical theory of Albert and Welton. In making simple assumptions concerning the cross-sections, we have supposed that the propagation can ben reduced to a mono-kinetic problem. A system of orthonormal functions is then set up making it possible to calculate the flux leaving a planar source. This method generalises the results obtained by Platzek to the case where the elastic cross-sections are not isotropic, and make it possible in particular to define a displacement cross-section: extension of the diffusion coefficient. This method can be generalised to the case of neutron diffraction as a function of time, and to the study of slowing-down. Numerical results are given in an appendix for the following: H{sub 2}O, D{sub 2}O, Fe, Be, Pb, CH, CH{sub 2}. These cross-sections have been verified experimentally in water and in graphite for neutrons of 2.5 and 14 MeV using a SAMES accelerator and a 2 MeV Van De Graaff. (author) [French] Nous proposons une methode permettant de calculer l'efficacite biologique des neutrons rapides issus des sources de fission dans la protection d'une pile. Cette methode justifie la theorie empirique d'Albert et Welton. En faisant des hypotheses simples sur les sections efficaces, nous avons suppose que la propagation pouvait etre ramenee a un probleme monocinetique. Nous construisons alors un systeme de fonctions orthonormales qui permet de calculer le flux issu d'une source plane. Cette methode generalise les resultats obtenus par Platzek au cas ou les sections efficaces elastiques ne sont pas isotropes et en particulier permet de definir une section efficace de deplacement: extension du coefficient de diffusion. Cette methode peut etre generalisee a la diffusion des neutrons en fonction du temps et a l'etude du ralentissement. Les resultats numeriques sont donnes en annexe pour les corps. H{sub 2

Comparison and analysis of 1D/2D/3D neutronics modeling for a fusion reactor

International Nuclear Information System (INIS)

Li, J.; Zeng, Q.; Chen, M.; Jiang, J.; Wu, Y.

2007-01-01

During the course of analyzing the characteristics for fusion reactors, the refined calculations are needed to confirm that the nuclear design requirements are met. Since the long computational time is consumed, the refined three-dimensional (3D) representation has been used primarily for establishing the baseline reference values, analyzing problems which cannot be reduced by symmetry considerations to lower dimensions, or where a high level of accuracy is desired locally. The two-dimensional (2D) or one-dimensional (1D) description leads itself readily to resolve many problems, such as the studies for the material fraction optimization, or for the blanket size optimization. The purpose of this paper is to find out the differences among different geometric descriptions, which can guide the way to approximate and simplify the computational model. The fusion power reactor named FDS-II was designed as an advanced fusion power reactor to demonstrate and validate the commercialization of fusion power by Institute of Plasma Physics, Chinese Academy of Science. In this contribution, the dual-cooled lithium lead (DLL) blanket of FDS-II was used as a reference for neutronics comparisons and analyses. The geometric descriptions include 1D concentric sphere model, 1D, 2D and 3D cylinder models. The home-developed multi-functional neutronics analysis code system VisualBUS, the Monte Carlo transport code MCNP and nuclear data library HENDL have been used for these analyses. The neutron wall loading distribution, tritium breeding ratio (TBR) and nuclear heat were calculated to evaluate the nuclear performance. The 3D calculation has been used as a comparison reference because it has the least errors in the treatment of geometry. It is suggested that the value of TBR calculated by the 1D approach should be greater than 1.3 to satisfy the practical need of tritium self-sufficiency. The distribution of nuclear heat based on the 2D and 3D models were similar since they all consider

Derivation of the neutron diffusion equation

International Nuclear Information System (INIS)

Mika, J.R.; Banasiak, J.

1994-01-01

We discuss the diffusion equation as an asymptotic limit of the neutron transport equation for large scattering cross sections. We show that the classical asymptotic expansion procedure does not lead to the diffusion equation and present two modified approaches to overcome this difficulty. The effect of the initial layer is also discussed. (authors). 9 refs

User's manual ACE/ONED (Version 1.0)

International Nuclear Information System (INIS)

Lee, Ki Bok; Lee, Jeong Chan; Song, Jae Seung; Lee, Chang Kyu; Ji, Sung Kyun; Song, Jae Woong; Kim, Yong Rae; Chang, Jong Hwa

1996-03-01

This report explains installation of ACE/ONED code, structure of input and output, how to prepare input and introduces some sample inputs. ACE/ONED developed by KAERI is a two-group one-dimensional diffusion theory code for nuclear design and reactor simulations. The usage of ACE/ONED encompasses core follow calculation, load-following calculation, plant power control simulation, xenon oscillation simulation, control rod maneuvering, and so on. ACE/ONED programmed of FORTRAN 77 in most part can be run on almost all kinds of computer including personal computer. 4 tabs., 4 figs., 8 refs. (Author) .new

Albedo-adjusted fast-neutron diffusion coefficients in reactor reflectors

International Nuclear Information System (INIS)

Terney, W.B.

1975-01-01

In the newer, larger pressurized-water reactor cores, the calculated power distributions are fairly sensitive to the number of neutron groups used and to the treatment of the reflector cross sections. Comparisons between transport and diffusion calculations show that the latter substantially underpredict the reflector albedos in the fast (top) group and that the power distribution is shifted toward the core center when compared to 4-group transport theory results. When the fast-neutron diffusion coefficients are altered to make the transport- and diffusion-theory albedos agree, the power distributions are also brought into agreement. An expression for the fast-neutron diffusion coefficients in reflector regions has been derived such that the diffusion calculation reproduces the albedo obtained from a transport solution. In addition, a correction factor for mesh effects applicable to coarse mesh problems is presented. The use of the formalism gives the correct albedos and improved power distributions. (U.S.)

TRACE/VALKIN: a neutronics-thermohydraulics coupled code to analyze strong 3D transients

Energy Technology Data Exchange (ETDEWEB)

Rafael Miro; Gumersindo Verdu; Ana Maria Sanchez [Chemical and Nuclear Engineering Department. Polytechnic University of Valencia. Cami de Vera s/n. 46022 Valencia (Spain); Damian Ginestar [Applied Mathematics Department. Polytechnic University of Valencia. Cami de Vera s/n. 46022 Valencia (Spain)

2005-07-01

Full text of publication follows: A nuclear reactor simulator consists mainly of two different blocks, which solve the models used for the basic physical phenomena taking place in the reactor. In this way, there is a neutronic module which simulates the neutron balance in the reactor core, and a thermal-hydraulics module, which simulates the heat transfer in the fuel, the heat transfer from the fuel to the water, and the different condensation and evaporation processes taking place in the reactor core and in the condenser systems. TRACE is a two-phase, two-fluid thermal-hydraulic reactor systems analysis code. The TRACE acronym stands for TRAC/RELAP Advanced Computational Engine, reflecting its ability to run both RELAP5 and TRAC legacy input models. It includes a three-dimensional kinetics module called PARCS for performing advanced analysis of coupled core thermal-hydraulic/kinetics problems. TRACE-VALKIN code is a new time domain analysis code to study transients in LWR reactors. This code uses the best estimate code TRACE to give account of the heat transfer and thermal-hydraulic processes, and a 3D neutronics module. This module has two options, the MODKIN option that makes use of a modal method based on the assumption that the neutronic flux can be approximately expanded in terms of the dominant lambda modes associated with a static configuration of the reactor core, and the NOKIN option that uses a one-step backward discretization of the neutron diffusion equation. The lambda modes are obtained using the Implicit Restarted Arnoldi approach or the Jacob-Davidson algorithm. To check the performance of the coupled code TRACE-VALKIN against complex 3D neutronic transients, using the cross-sections tables generated with the translator SIMTAB from SIMULATE to TRACE/VALKIN, the Cofrentes NPP SCRAM-61 transient is simulated. Cofrentes NPP is a General Electric BWR-6 design located in Valencia-land (Spain). It is in operation since 1985 and currently in its fifteenth

The Association Analysis between ACE and ACTN3 Genes Polymorphisms and Endurance Capacity in Young Cross-Country Skiers: Longitudinal Study

Directory of Open Access Journals (Sweden)

Agnes Mägi, Eve Unt, Ele Prans, Liina Raus, Jaan Eha, Alar Veraksitš, Külli Kingo, Sulev Kõks

2016-06-01

Full Text Available Endurance performance depends on the integration of several phenotypic traits influenced by multiple environmental and genetic factors. Objectives of the study were: (1 to examine the genotypic frequencies of the ACE I/D, ACTN3 R577X polymorphisms and endurance performance-related phenotypes, (2 to evaluate the dynamics of endurance performance parameters during a 5-year period in relation to ACE I/D and ACTN3 R577X genotypes in Estonian young skiers. Determination of VO2peak was performed in 58 skiers aged 15-19 years (41 males, 17 females during a 5-year period. The control group consisted of 322 healthy non-athletic subjects (145 males, 177 females. The study groups were genotyped for the ACE I/D and ACTN3 R577X variants. Frequencies of the ACE ID and ACTN3 RR genotypes were significantly higher (p = 0.047 and p = 0.003, respectively and the RX genotype was lower (p = 0.008 in young male skiers compared with controls. A significant relationship was found between change (Δ of training volume and ΔVO2peak (mL·kg-1·min-1 (r = 0.475, p = 0.002. No significant main effect was detected between VO2peak (mL·kg-1·min-1 dynamics (comparison with the previous age group data and ACE I/D and ACTN3 R577X genotypes interactions (F = 0.571, p = 0.770 and F = 0.650 and p = 0.705, respectively in all young skiers. Study results indicated a significantly higher frequency of the ACE ID and ACTN3 RR genotypes among Estonian young male skiers compared with the male control group. Significant genotype-related differences in dynamics of VO2peak during a 5-year period were not found. In the future, longitudinal research including different gene variants may contribute to a better understanding of the nature of endurance performance.

Reflector modelization for neutronic diffusion and parameters identification

International Nuclear Information System (INIS)

Argaud, J.P.

1993-04-01

Physical parameters of neutronic diffusion equations can be adjusted to decrease calculations-measurements errors. The reflector being always difficult to modelize, we choose to elaborate a new reflector model and to use the parameters of this model as adjustment coefficients in the identification procedure. Using theoretical results, and also the physical behaviour of neutronic flux solutions, the reflector model consists then in its replacement by boundary conditions for the diffusion equations on the core only. This theoretical result of non-local operator relations leads then to some discrete approximations by taking into account the multiscaled behaviour, on the core-reflector interface, of neutronic diffusion solutions. The resulting model of this approach is then compared with previous reflector modelizations, and first results indicate that this new model gives the same representation of reflector for the core than previous. (author). 12 refs

Neutron energy spectra of sup 2 sup 5 sup 2 Cf, Am-Be source and of the D(d,n) sup 3 He reaction

CERN Document Server

Sang Tae Park

2003-01-01

The neutron energy spectrum of the following sources were measured using a fast neutron spectrometer with the NE-213 liquid scintillator: sup 2 sup 5 sup 2 Cf, Am-Be and D(d,n) sup 3 He reaction from a 3 MeV Pelletron accelerator in Tokyo Institute of Technology. The measured proton recoil pulse height data of sup 2 sup 5 sup 2 Cf, Am-Be and D(d,n) sup 3 He were unfolded using the mathematical program to obtain the neutron energy spectrum. The sup 2 sup 5 sup 2 Cf and Am-Be neutron energy spectra were measured and the results obtained showed a good agreement with the spectra usually published in the literature. The neutron energy spectrum from D(d,n) sup 3 He was measured and the results obtained also showed a good agreement with the calculation by time of flight (TOF) methods. (author)

Parallel computing for homogeneous diffusion and transport equations in neutronics

International Nuclear Information System (INIS)

Pinchedez, K.

1999-06-01

Parallel computing meets the ever-increasing requirements for neutronic computer code speed and accuracy. In this work, two different approaches have been considered. We first parallelized the sequential algorithm used by the neutronics code CRONOS developed at the French Atomic Energy Commission. The algorithm computes the dominant eigenvalue associated with PN simplified transport equations by a mixed finite element method. Several parallel algorithms have been developed on distributed memory machines. The performances of the parallel algorithms have been studied experimentally by implementation on a T3D Cray and theoretically by complexity models. A comparison of various parallel algorithms has confirmed the chosen implementations. We next applied a domain sub-division technique to the two-group diffusion Eigen problem. In the modal synthesis-based method, the global spectrum is determined from the partial spectra associated with sub-domains. Then the Eigen problem is expanded on a family composed, on the one hand, from eigenfunctions associated with the sub-domains and, on the other hand, from functions corresponding to the contribution from the interface between the sub-domains. For a 2-D homogeneous core, this modal method has been validated and its accuracy has been measured. (author)

Computation of 3D neutron fluxes in one pin hexagonal cell

International Nuclear Information System (INIS)

Prabha, Hem; Marleau, Guy

2013-01-01

Highlights: ► Computations of 3D neutron fluxes in one pin hexagonal cell is performed by Carlvik’s method of collision probability. ► Carlvik’s method requires computation of track lengths in the geometry. ► Equations are developed to compute tracks, in 2D and 3D, in hexagons and are implemented in a program HX7. ► The program HX7 is implemented in NXT module of the code DRAGON, where tracks in pins are computed. ► The tracks are plotted and fluxes are compared with the EXCELT module of the code DRAGON. - Abstract: In this paper we are presenting the method of computation of three dimensional (3D) neutron fluxes in one pin hexagonal cell. Carlvik’s collision probability method of solving neutron transport equation for computing fluxes has been used here. This method can consider exact geometrical details of the given geometry. While using this method, track length computations are required to be done. We have described here the method of computing tracks in one 3D hexagon. A program HX7 has been developed for this purpose. This program has been implemented in the NXT module of the code DRAGON, where tracks in the pins are computed. For computing tracks in 3D, first we use the tracks computed in the two dimensions (2D) and then we project them in the third dimension. We have developed equations for this purpose. In both the regions, fuel pin as well as in the moderator surrounding the pin the fluxes are assumed to be uniform. A uniform source is assumed in the moderator region. Reflecting boundary conditions are applied on all the sides as well as on the top and bottom surfaces. One group 2D and 3D fluxes are compared with the respective results obtained by the EXCELT module of DRAGON. To check the computations, tracks are plotted and errors in the computations are obtained. It is observed by using both the modules EXCELT and NXT that the fluxes in the pins converge faster and in the moderator region fluxes converge very slowly

HAMMER, 1-D Multigroup Neutron Transport Infinite System Cell Calculation for Few-Group Diffusion Calculation

International Nuclear Information System (INIS)

Honeck, H.C.

1984-01-01

1 - Description of problem or function: HAMMER performs infinite lattice, one-dimensional cell multigroup calculations, followed (optionally) by one-dimensional, few-group, multi-region reactor calculations with neutron balance edits. 2 - Method of solution: Infinite lattice parameters are calculated by means of multigroup transport theory, composite reactor parameters by few-group diffusion theory. 3 - Restrictions on the complexity of the problem: - Cell calculations - maxima of: 30 thermal groups; 54 epithermal groups; 20 space points; 20 regions; 18 isotopes; 10 mixtures; 3 thermal up-scattering mixtures; 200 resonances per group; no overlap or interference; single level only. - Reactor calculations - maxima of : 40 regions; 40 mixtures; 250 space points; 4 groups

Prediction of the neutrons subcritical multiplication using the diffusion hybrid equation with external neutron sources

Energy Technology Data Exchange (ETDEWEB)

Costa da Silva, Adilson; Carvalho da Silva, Fernando [COPPE/UFRJ, Programa de Engenharia Nuclear, Caixa Postal 68509, 21941-914, Rio de Janeiro (Brazil); Senra Martinez, Aquilino, E-mail: aquilino@lmp.ufrj.br [COPPE/UFRJ, Programa de Engenharia Nuclear, Caixa Postal 68509, 21941-914, Rio de Janeiro (Brazil)

2011-07-15

Highlights: > We proposed a new neutron diffusion hybrid equation with external neutron source. > A coarse mesh finite difference method for the adjoint flux and reactivity calculation was developed. > 1/M curve to predict the criticality condition is used. - Abstract: We used the neutron diffusion hybrid equation, in cartesian geometry with external neutron sources to predict the subcritical multiplication of neutrons in a pressurized water reactor, using a 1/M curve to predict the criticality condition. A Coarse Mesh Finite Difference Method was developed for the adjoint flux calculation and to obtain the reactivity values of the reactor. The results obtained were compared with benchmark values in order to validate the methodology presented in this paper.

Prediction of the neutrons subcritical multiplication using the diffusion hybrid equation with external neutron sources

International Nuclear Information System (INIS)

Costa da Silva, Adilson; Carvalho da Silva, Fernando; Senra Martinez, Aquilino

2011-01-01

Highlights: → We proposed a new neutron diffusion hybrid equation with external neutron source. → A coarse mesh finite difference method for the adjoint flux and reactivity calculation was developed. → 1/M curve to predict the criticality condition is used. - Abstract: We used the neutron diffusion hybrid equation, in cartesian geometry with external neutron sources to predict the subcritical multiplication of neutrons in a pressurized water reactor, using a 1/M curve to predict the criticality condition. A Coarse Mesh Finite Difference Method was developed for the adjoint flux calculation and to obtain the reactivity values of the reactor. The results obtained were compared with benchmark values in order to validate the methodology presented in this paper.

The Association Analysis between ACE and ACTN3 Genes Polymorphisms and Endurance Capacity in Young Cross-Country Skiers: Longitudinal Study.

Science.gov (United States)

Mägi, Agnes; Unt, Eve; Prans, Ele; Raus, Liina; Eha, Jaan; Veraksitš, Alar; Kingo, Külli; Kõks, Sulev

2016-06-01

Endurance performance depends on the integration of several phenotypic traits influenced by multiple environmental and genetic factors. Objectives of the study were: (1) to examine the genotypic frequencies of the ACE I/D, ACTN3 R577X polymorphisms and endurance performance-related phenotypes, (2) to evaluate the dynamics of endurance performance parameters during a 5-year period in relation to ACE I/D and ACTN3 R577X genotypes in Estonian young skiers. Determination of VO2peak was performed in 58 skiers aged 15-19 years (41 males, 17 females) during a 5-year period. The control group consisted of 322 healthy non-athletic subjects (145 males, 177 females). The study groups were genotyped for the ACE I/D and ACTN3 R577X variants. Frequencies of the ACE ID and ACTN3 RR genotypes were significantly higher (p = 0.047 and p = 0.003, respectively) and the RX genotype was lower (p = 0.008) in young male skiers compared with controls. A significant relationship was found between change (Δ) of training volume and ΔVO2peak (mL·kg(-1)·min(-1)) (r = 0.475, p = 0.002). No significant main effect was detected between VO2peak (mL·kg(-1)·min(-1)) dynamics (comparison with the previous age group data) and ACE I/D and ACTN3 R577X genotypes interactions (F = 0.571, p = 0.770 and F = 0.650 and p = 0.705, respectively) in all young skiers. Study results indicated a significantly higher frequency of the ACE ID and ACTN3 RR genotypes among Estonian young male skiers compared with the male control group. Significant genotype-related differences in dynamics of VO2peak during a 5-year period were not found. In the future, longitudinal research including different gene variants may contribute to a better understanding of the nature of endurance performance. Key pointsSignificantly higher prevalence of the ACE ID and the ACTN3 RR genotypes were found among Estonian young male skiers compared with the male control group, which may be an advantage for the explosive speed and power

D-D neutron generator development at LBNL.

Science.gov (United States)

Reijonen, J; Gicquel, F; Hahto, S K; King, M; Lou, T-P; Leung, K-N

2005-01-01

The plasma and ion source technology group in Lawrence Berkeley National Laboratory is developing advanced, next generation D-D neutron generators. There are three distinctive developments, which are discussed in this presentation, namely, multi-stage, accelerator-based axial neutron generator, high-output co-axial neutron generator and point source neutron generator. These generators employ RF-induction discharge to produce deuterium ions. The distinctive feature of RF-discharge is its capability to generate high atomic hydrogen species, high current densities and stable and long-life operation. The axial neutron generator is designed for applications that require fast pulsing together with medium to high D-D neutron output. The co-axial neutron generator is aimed for high neutron output with cw or pulsed operation, using either the D-D or D-T fusion reaction. The point source neutron generator is a new concept, utilizing a toroidal-shaped plasma generator. The beam is extracted from multiple apertures and focus to the target tube, which is located at the middle of the generator. This will generate a point source of D-D, T-T or D-T neutrons with high output flux. The latest development together with measured data will be discussed in this article.

Prevalence of alpha actinin-3 gene (ACTN3) R577X and angiotensin converting enzyme (ACE) insertion / deletion gene polymorphisms in national and amateur Turkish athletes.

Science.gov (United States)

Eroğlu, Onur; Zileli, Rayif; Nalbant, M Ali; Ulucan, Korkut

2018-04-30

Studies to date showed the importance of alpha- actinin-3 (ACTN3) R577X and angiotensin converting enzyme (ACE) ID polymorphisms on determining athletic performance. Therefore, in this study, we aimed to examine polymorphisms given to Turkish athletes and compare them with sedentary individuals. Genomic DNAs were extracted from peripheral blood by using commercially available DNA isolation kit (Macherey-Nagel, NucleoSpin®, Germany). For this study, a total of 84 volunteers (23 national athletes, 27 amateur athletes and 34 sedentary controls) was recruited.  ACE ID genotypes were determined by conventional polymerase chain reaction, and ACTN3 R577X polymorphisms by polymerase chain reaction- restriction fragment length polymorphism methodology.   In ACTN3 R577X polymorphism, RX was the dominating genotype, and we detected no RR genotype in national athletes. (no RR genotype was detected in national athletes) X allele is more frequent in national athletes and R allele was more frequent in both amateur athletes and control group. II genotype was more frequent in national athletes and in control group, whereas DD genotype was more frequent in amateur athletes for ACE ID polymorphism. When we consider alleles, D allele was found more frequently in amateur athletes and control group whereas I allele was more frequent in national athletes in ACE ID polymorphism. For ACTN3, X allele was superior to R allele. ACTN3 R577X and ACE ID polymorphisms were important biomarkers in determining athletic performance. However, our results in Turkish athletes suggest that ACE D allele and ACTN3 X alleles may be beneficial to athletes potentially, regardless of the distance they perform.

Three-dimensional multiple reciprocity boundary element method for one-group neutron diffusion eigenvalue computations

International Nuclear Information System (INIS)

Itagaki, Masafumi; Sahashi, Naoki.

1996-01-01

The multiple reciprocity method (MRM) in conjunction with the boundary element method has been employed to solve one-group eigenvalue problems described by the three-dimensional (3-D) neutron diffusion equation. The domain integral related to the fission source is transformed into a series of boundary-only integrals, with the aid of the higher order fundamental solutions based on the spherical and the modified spherical Bessel functions. Since each degree of the higher order fundamental solutions in the 3-D cases has a singularity of order (1/r), the above series of boundary integrals requires additional terms which do not appear in the 2-D MRM formulation. The critical eigenvalue itself can be also described using only boundary integrals. Test calculations show that Wielandt's spectral shift technique guarantees rapid and stable convergence of 3-D MRM computations. (author)

SCRAM reactivity calculations with the KIKO3D code

International Nuclear Information System (INIS)

Hordosy, G.; Kerszturi, A.; Maraczy, Cs.; Temesvari, E.

1999-01-01

Discrepancies between calculated static reactivities and measured reactivities evaluated with reactivity meters led to investigating SCRAM with the KIKO3D dynamic code, The time and space dependent neutron flux in the reactor core during the rod drop measurement was calculated by the KIKO3D nodal diffusion code. For calculating the ionisation chamber signals the Green function technique was applied. The Green functions of ionisation chambers were evaluated via solving the neutron transport equation in the reflector regions with the MCNP Monte Carlo code. The detector signals during asymmetric SCRAM measurements were calculated and compared with measured data using the inverse point kinetics transformation. The sufficient agreement validates the KIKO3D code to determine the reactivities after SCRAM. (Authors)

SRAC2006: A comprehensive neutronics calculation code system

International Nuclear Information System (INIS)

Okumura, Keisuke; Kugo, Teruhiko; Kaneko, Kunio; Tsuchihashi, Keichiro

2007-02-01

The SRAC is a code system applicable to neutronics analysis of a variety of reactor types. Since the publication of the second version of the users manual (JAERI-1302) in 1986 for the SRAC system, a number of additions and modifications to the functions and the library data have been made to establish a comprehensive neutronics code system. The current system includes major neutron data libraries (JENDL-3.3, JENDL-3.2, ENDF/B-VII, ENDF/B-VI.8, JEFF-3.1, JEF-2.2, etc.), and integrates five elementary codes for neutron transport and diffusion calculation; PIJ based on the collision probability method applicable to 16 kind of lattice models, S N transport codes ANISN(1D) and TWOTRN(2D), diffusion codes TUD(1D) and CITATION(multi-D). The system also includes an auxiliary code COREBN for multi-dimensional core burn-up calculation. (author)

FEMB, 2-D Homogeneous Neutron Diffusion in X-Y Geometry with Keff Calculation, Dyadic Fission Matrix

International Nuclear Information System (INIS)

Misfeldt, I.B.

1987-01-01

1 - Nature of physical problem solved: The two-dimensional neutron diffusion equation (xy geometry) is solved in the homogeneous form (K eff calculation). The boundary conditions specify each group current as a linear homogeneous function of the group fluxes (gamma matrix concept). For each material, the fission matrix is assumed to be dyadic. 2 - Method of solution: Finite element formulation with Lagrange type elements. Solution technique: SOR with extrapolation. 3 - Restrictions on the complexity of the problem: Maximum order of the Lagrange elements is 6

TRITON, 3-D Multi-Region Neutron Diffusion Burnup with Criticality Search

International Nuclear Information System (INIS)

1974-01-01

1 - Nature of physical problem solved: TRITON is a multigroup diffusion depletion program in three dimensions (x,y,z). In addition to the straight K eff calculation, three types of criticality searches are possible - diluted control isotope search, region-wise smeared control isotope search, region-wise smeared control isotope search, region-wise smeared control isotope boundary search (the control isotope can be smeared over one region or over a group of regions called a control bank). The depletion equations are solved region-wise. More than one microscopic cross section library can be used in the various regions of the reactor. The same is true for self-shielding factors. Such sets of data can be changed at pre-determined time steps. 2 - Method of solution: The mathematical model employed for the solution of the finite difference equations, which is derived from a seven-point approximation of diffusion equations, is an on-line Chebyshev semi- iterative method. 3 - Restrictions on the complexity of the problem: Maximum number of: library sets: 1; self-shielding sets: 10; compositions: 100; self-shielding coefficients: 6000; groups: 10; fuel isotopes: 30; fission products: 29; isotopes: 50; burnable isotopes: 40; control banks: 100; mesh points: 15000; regions: 400; time steps: 100; control areas: 100; small time steps: 200; elements in the control list: 400; x planes: 100; y planes: 100; z planes: 100

Neutron diffusion: connection with the theory of browniam motion

International Nuclear Information System (INIS)

Dellagi, Mohamed

1977-01-01

The displacement of the neutron projection on an axis Ox and its density of probability are introduced instead of describing the diffusion theory with neutron density, as is usual. If the point source O is isotropic and neutron monoenergetic, the brownian particle described by Langevin's equation and neutron have the same time correlation of velocity [fr

The program FEM3D users manual

International Nuclear Information System (INIS)

Misfeldt, I.

1977-11-01

A short description of the program FEM3D that solves the three-dimensional, multigroup, neutron diffusion equation by the finite element method. The elements are box-formed Lagrange type elements of order 1, 2, or 3. The program gives very reliable results within reasonable calculation times, but it is not a fast program and should therefore mostly be used where high precision is needed. (author/BP)

Tritium release behavior from neutron-irradiated Li{sub 2}TiO{sub 3} single crystal

Energy Technology Data Exchange (ETDEWEB)

Tanifuji, Takaaki; Yamaki, Daiju; Noda, Kenji [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Nasu, Shoichi

1998-03-01

Li{sub 2}TiO{sub 3} single-crystals with various size (1-2mm) were used as specimens. After the irradiation up to 4 x 10{sup 18} n/cm{sup 2} with thermal neutrons in JRR-2, tritium release from the Li{sub 2}TiO{sub 3} specimens in isothermal heating tests was continuously measured with a proportional counter. The tritium release in the range from 625K to 1373K seems to be controlled by bulk diffusion. The tritium diffusion coefficient (D{sub T}) in Li{sub 2}TiO{sub 3} was evaluated to be D{sub T}(cm{sup 2}/sec) = 0.100exp(-104(kJ/mol)/RT), 625Kdiffusion coefficients in Li{sub 2}TiO{sub 3} is almost equal to those of Li{sub 2}O irradiated with thermal neutrons up to 2 x 10{sup 19} n/cm{sup 2}. It indicates that the tritium release performance of Li{sub 2}TiO{sub 3} is essentially good as Li{sub 2}O. (author)

Propagation of thermal neutrons in mock-up screw-shaped steel elements with water protection; Propagation des neutrons thermiques dans des fausses cartouches d'acier en helice dans une protection d'eau. Programme tournesol 3

Energy Technology Data Exchange (ETDEWEB)

Devillers, C L; Lanore, J M [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1967-07-01

This report treats the streaming of thermal neutrons in a cylindrical duct in light water. The duct contains a spiral iron shield. Transmission and reflection matrices are used to describe the probabilities for the thermal neutrons to be absorbed or to be scattered on the surfaces. The neutron paths across the void are represented by geometrical matrices. The numerical resolution is performed by the Monte-Carlo method. (authors) [French] Dans ce rapport on traite un probleme de fuites de neutrons thermiques dans un canal cylindrique plonge dans l'eau et obture par un ecran helicoidal en acier. On utilise des matrices de transmission-reflexion pour decrire les probabilites d'absorption et de diffusion des neutrons sur les parois et l'helicoide et des matrices de correspondance geometrique pour representer la propagation dans le vide. La resolution numerique se fait par une methode de Monte-Carlo. (auteur)

The importance of association between angiotensin-converting enzyme (ACE) Gene I/D polymorphism and diabetic peripheral neuropathy.

Science.gov (United States)

Inanir, Ahmet; Basol, Nursah; Karakus, Nevin; Yigit, Serbulent

2013-11-10

Diabetic peripheral neuropathy (DPN) is a microvascular complication of diabetes mellitus (DM) due to decreasing quality of life. In the present study, it is aimed to evaluate angiotensin-converting enzyme (ACE) Gene I/D polymorphism in Turkish population. Two hundred and thirty-five DPN patients and two hundred and eighty-one controls were enrolled in this study. Genomic DNA was isolated and genotyped using polymerase chain reaction (PCR) analyses for the ACE gene I/D polymorphism. Baseline characteristics of the DPN patients according to ACE genotypes were similar, except for history of hypertension. The frequency of II genotype was significantly higher in patients with positive history of hypertension than the patients with negative history of hypertension (p=0.013). DD genotype of I/D polymorphism was found to be a susceptibility factor for DPN in homozygous form (p=0.032). According to allele frequencies, D allele of I/D polymorphism was found to be a susceptibility factor for DPN (p=0.031). ACE gene I/D polymorphism may research in DM patients to determine genetic predisposition for DPN. It can be useful for taking early measures and avoiding DPN in a Turkish population. © 2013 Elsevier B.V. All rights reserved.

Coupling calculation of CFD-ACE computational fluid dynamics code and DeCART whole-core neutron transport code for development of numerical reactor

Energy Technology Data Exchange (ETDEWEB)

Shin, Chang Hwan; Seo, Kyong Won; Chun, Tae Hyun; Kim, Kang Seog

2005-03-15

Code coupling activities have so far focused on coupling the neutronics modules with the CFD module. An interface module for the CFD-ACE/DeCART coupling was established as an alternative to the original STAR-CD/DeCART interface. The interface module for DeCART/CFD-ACE was validated by single-pin model. The optimized CFD mesh was decided through the calculation of multi-pin model. It was important to consider turbulent mixing of subchannels for calculation of fuel temperature. For the parallel calculation, the optimized decompose process was necessary to reduce the calculation costs and setting of the iteration and convergence criterion for each code was important, too.

Coupling calculation of CFD-ACE computational fluid dynamics code and DeCART whole-core neutron transport code for development of numerical reactor

International Nuclear Information System (INIS)

Shin, Chang Hwan; Seo, Kyong Won; Chun, Tae Hyun; Kim, Kang Seog

2005-03-01

Code coupling activities have so far focused on coupling the neutronics modules with the CFD module. An interface module for the CFD-ACE/DeCART coupling was established as an alternative to the original STAR-CD/DeCART interface. The interface module for DeCART/CFD-ACE was validated by single-pin model. The optimized CFD mesh was decided through the calculation of multi-pin model. It was important to consider turbulent mixing of subchannels for calculation of fuel temperature. For the parallel calculation, the optimized decompose process was necessary to reduce the calculation costs and setting of the iteration and convergence criterion for each code was important, too

Fission multipliers for D-D/D-T neutron generators

International Nuclear Information System (INIS)

Lou, T.P.; Vujic, J.L.; Koivunoro, H.; Reijonen, J.; Leung, K.-N.

2003-01-01

A compact D-D/D-T fusion based neutron generator is being designed at the Lawrence Berkeley National Laboratory to have a potential yield of 10 12 D-D n/s and 10 14 D-T n/s. Because of its high neutron yield and compact size (∼20 cm in diameter by 4 cm long), this neutron generator design will be suitable for many applications. However, some applications required higher flux available from nuclear reactors and spallation neutron sources operated with GeV proton beams. In this study, a subcritical fission multiplier with k eff of 0.98 is coupled with the compact neutron generators in order to increase the neutron flux output. We have chosen two applications to show the gain in flux due to the use of fission multipliers--in-core irradiation and out-of-core irradiation. For the in-core irradiation, we have shown that a gain of ∼25 can be achieved in a positron production system using D-T generator. For the out-of-core irradiation, a gain of ∼17 times is obtained in Boron Neutron Capture Therapy (BNCT) using a D-D neutron generator. The total number of fission neutrons generated by a source neutron in a fission multiplier with k eff is ∼50. For the out-of-core irradiation, the theoretical maximum net multiplication is ∼30 due to the absorption of neutrons in the fuel. A discussion of the achievable multiplication and the theoretical multiplication will be presented in this paper

MICADO: Parallel implementation of a 2D-1D iterative algorithm for the 3D neutron transport problem in prismatic geometries

International Nuclear Information System (INIS)

Fevotte, F.; Lathuiliere, B.

2013-01-01

The large increase in computing power over the past few years now makes it possible to consider developing 3D full-core heterogeneous deterministic neutron transport solvers for reference calculations. Among all approaches presented in the literature, the method first introduced in [1] seems very promising. It consists in iterating over resolutions of 2D and ID MOC problems by taking advantage of prismatic geometries without introducing approximations of a low order operator such as diffusion. However, before developing a solver with all industrial options at EDF, several points needed to be clarified. In this work, we first prove the convergence of this iterative process, under some assumptions. We then present our high-performance, parallel implementation of this algorithm in the MICADO solver. Benchmarking the solver against the Takeda case shows that the 2D-1D coupling algorithm does not seem to affect the spatial convergence order of the MOC solver. As for performance issues, our study shows that even though the data distribution is suited to the 2D solver part, the efficiency of the ID part is sufficient to ensure a good parallel efficiency of the global algorithm. After this study, the main remaining difficulty implementation-wise is about the memory requirement of a vector used for initialization. An efficient acceleration operator will also need to be developed. (authors)

Neutronics calculation of RTP core

Science.gov (United States)

Rabir, Mohamad Hairie B.; Zin, Muhammad Rawi B. Mohamed; Karim, Julia Bt. Abdul; Bayar, Abi Muttaqin B. Jalal; Usang, Mark Dennis Anak; Mustafa, Muhammad Khairul Ariff B.; Hamzah, Na'im Syauqi B.; Said, Norfarizan Bt. Mohd; Jalil, Muhammad Husamuddin B.

2017-01-01

Reactor calculation and simulation are significantly important to ensure safety and better utilization of a research reactor. The Malaysian's PUSPATI TRIGA Reactor (RTP) achieved initial criticality on June 28, 1982. The reactor is designed to effectively implement the various fields of basic nuclear research, manpower training, and production of radioisotopes. Since early 90s, neutronics modelling were used as part of its routine in-core fuel management activities. The are several computer codes have been used in RTP since then, based on 1D neutron diffusion, 2D neutron diffusion and 3D Monte Carlo neutron transport method. This paper describes current progress and overview on neutronics modelling development in RTP. Several important parameters were analysed such as keff, reactivity, neutron flux, power distribution and fission product build-up for the latest core configuration. The developed core neutronics model was validated by means of comparison with experimental and measurement data. Along with the RTP core model, the calculation procedure also developed to establish better prediction capability of RTP's behaviour.

Exploring the Link between ACE Insertion/Deletion (I/D Polymorphism and Uterine Leiomyomas

Directory of Open Access Journals (Sweden)

Shirin Shahbazi

2017-03-01

Full Text Available Introduction: Uterine leiomyomas arise from the proliferation of smooth muscle cells. ACE gene encodes a convertase enzyme mainly secreted in vascular endothelial cells which is involved in the renin–angiotensin system and blood pressure controlling. This gene has an insertion/deletion (I/D polymorphism correlates to serum and tissue ACE levels. The aim of this study is to elucidate the relationship between ACE gene variation and the development of myom. Methods: The samples of 55 uterine leiomyoma patients and 78 healthy women were studied. After obtaining informed consent, blood samples were collected and DNA extraction was performed by Salting-out method. Genotyping was performed using PCR reaction. The amplified products were two bands of 190 and 490 bp, which represents D allele and I allele, respectively. Statistical analysis was done using Chi-square test. Results: The D allele frequency was 0.55 in the patient group and 0.51 in the control group. The I allele frequencies in the two groups were 0.45 and 0.49, respectively. The results showed that taking the II genotype into account as reference genotype; homozygous DD individuals were at increased risk of uterine myoma (Odds ratio: 1.37. However, heterozygous ID showed a similar risk with the II genotype as the reference group. Conclusion: High blood pressure is significantly associated with uterine fibroids. It has been shown that atherosclerotic damage of uterine blood vessels and the inflammatory process caused by it may play an important role in the development of uterine myoma. This study indicates a positive relationship between the ACE (I/D polymorphism and the risk of uterine myoma. This finding is evidence of the important role of the renin–angiotensin system in the pathogenesis of myoma

Calculation of the power factor using the neutron diffusion hybrid equation

International Nuclear Information System (INIS)

Costa da Silva, Adilson; Carvalho da Silva, Fernando; Senra Martinez, Aquilino

2013-01-01

Highlights: ► A neutron diffusion hybrid equation with an external neutron source was used. ► Nodal expansion method to obtain the neutron flux was used. ► Nuclear power factors in each fuel element in the reactor core were calculated. ► The results obtained were very accurate. -- Abstract: In this paper, we used a neutron diffusion hybrid equation with an external neutron source to calculate nuclear power factors in each fuel element in the reactor core. We used the nodal expansion method to obtain the neutron flux for a given control rods bank position. The results were compared with results obtained for eigenvalue problem near criticality condition and fixed source problem during the start-up of the reactor, where external neutron sources are extremely important for the stabilization of external neutron detectors.

A point-centered diffusion differencing for unstructured meshes in 3-D

International Nuclear Information System (INIS)

Palmer, T.S.

1994-01-01

We describe a point-centered diffusion discretization for 3-D unstructured meshes of polyhedra. The method has several attractive qualities, including second-order accuracy and preservation of linear solutions. A potential drawback to the scheme is that the diffusion matrix is asymmetric, in general. Results of numerical test problems illustrate the behavior of the scheme

Discrete formulation for two-dimensional multigroup neutron diffusion equations

Energy Technology Data Exchange (ETDEWEB)

Vosoughi, Naser E-mail: vosoughi@mehr.sharif.edu; Salehi, Ali A.; Shahriari, Majid

2003-02-01

The objective of this paper is to introduce a new numerical method for neutronic calculation in a reactor core. This method can produce the final finite form of the neutron diffusion equation by classifying the neutronic variables and using two kinds of cell complexes without starting from the conventional differential form of the neutron diffusion equation. The method with linear interpolation produces the same convergence as the linear continuous finite element method. The quadratic interpolation is proven; the convergence order depends on the shape of the dual cell. The maximum convergence order is achieved by choosing the dual cell based on two Gauss' points. The accuracy of the method was examined with a well-known IAEA two-dimensional benchmark problem. The numerical results demonstrate the effectiveness of the new method.

Discrete formulation for two-dimensional multigroup neutron diffusion equations

International Nuclear Information System (INIS)

Vosoughi, Naser; Salehi, Ali A.; Shahriari, Majid

2003-01-01

The objective of this paper is to introduce a new numerical method for neutronic calculation in a reactor core. This method can produce the final finite form of the neutron diffusion equation by classifying the neutronic variables and using two kinds of cell complexes without starting from the conventional differential form of the neutron diffusion equation. The method with linear interpolation produces the same convergence as the linear continuous finite element method. The quadratic interpolation is proven; the convergence order depends on the shape of the dual cell. The maximum convergence order is achieved by choosing the dual cell based on two Gauss' points. The accuracy of the method was examined with a well-known IAEA two-dimensional benchmark problem. The numerical results demonstrate the effectiveness of the new method

Diffusion-weighted imaging of the rat pelvis using 3D water-excitation MP-RAGE MR sequence

International Nuclear Information System (INIS)

Numano, Tomokazu; Homma, Kazuhiro; Hyodo, Koji; Nitta, Naotaka; Iwasaki, Nobuaki

2008-01-01

We developed a novel technique for fat-saturated, 3-dimensional (3D) diffusion-weighted (DW) magnetic resonance (MR) imaging sequencing based upon the 3D magnetization-prepared, rapid gradient-echo (3D-MP-RAGE) method. We saturated fat using 2 techniques, chemical shift selective (CHESS; FatSat)-3D-DWI sequence versus water excitation (WE)-3D-DWI method, then compared the 2 sequences in terms of degree of fat suppression. In preparing the FatSat-3D-DWI sequence, we used a ''CHESS-90deg radiofrequency (RF)-motion probing gradient (MPG)-180deg RFMPG-90deg RF'' pulse-train, to sensitize the magnetization to fat-saturated diffusion. In contrast, in the WE-3D-DWI sequence, we selected a RAGE-excitation pulse with a binominal-pulse 1-1 or 1-2-1 for water-excited (fat-saturated) diffusion imaging. Experimental results in a phantom confirmed the effects of diffusion weighting and of fat saturation. Fat saturation was much better in the WE-3D-DWI sequence than the CHESS-3D-DWI sequence. From results from animal (rat pelvis) experiments using WE-3D-DWI, we obtained fat-saturated DWI. This sequence was useful for in vivo imaging. (author)

Verification of SIGACE code for generating ACE format cross-section files with continuous energy at high temperature

International Nuclear Information System (INIS)

Li Zhifeng; Yu Tao; Xie Jinsen; Qin Mian

2012-01-01

Based on the recently released ENDF/B-VII. 1 library, high temperature neutron cross-section files are generated through SIGACE code using low temperature ACE format files. To verify the processed ACE file of SIGACE, benchmark calculations are performed in this paper. The calculated results of selected ICT, standard CANDU assembly, LWR Doppler coefficient and SEFOR benchmarks are well conformed with reference value, which indicates that high temperature ACE files processed by SIGACE can be used in related neutronics calculations. (authors)

Isotropic resolution diffusion tensor imaging of lumbosacral and sciatic nerves using a phase-corrected diffusion-prepared 3D turbo spin echo.

Science.gov (United States)

Cervantes, Barbara; Van, Anh T; Weidlich, Dominik; Kooijman, Hendrick; Hock, Andreas; Rummeny, Ernst J; Gersing, Alexandra; Kirschke, Jan S; Karampinos, Dimitrios C

2018-08-01

To perform in vivo isotropic-resolution diffusion tensor imaging (DTI) of lumbosacral and sciatic nerves with a phase-navigated diffusion-prepared (DP) 3D turbo spin echo (TSE) acquisition and modified reconstruction incorporating intershot phase-error correction and to investigate the improvement on image quality and diffusion quantification with the proposed phase correction. Phase-navigated DP 3D TSE included magnitude stabilizers to minimize motion and eddy-current effects on the signal magnitude. Phase navigation of motion-induced phase errors was introduced before readout in 3D TSE. DTI of lower back nerves was performed in vivo using 3D TSE and single-shot echo planar imaging (ss-EPI) in 13 subjects. Diffusion data were phase-corrected per k z plane with respect to T 2 -weighted data. The effects of motion-induced phase errors on DTI quantification was assessed for 3D TSE and compared with ss-EPI. Non-phase-corrected 3D TSE resulted in artifacts in diffusion-weighted images and overestimated DTI parameters in the sciatic nerve (mean diffusivity [MD] = 2.06 ± 0.45). Phase correction of 3D TSE DTI data resulted in reductions in all DTI parameters (MD = 1.73 ± 0.26) of statistical significance (P ≤ 0.001) and in closer agreement with ss-EPI DTI parameters (MD = 1.62 ± 0.21). DP 3D TSE with phase correction allows distortion-free isotropic diffusion imaging of lower back nerves with robustness to motion-induced artifacts and DTI quantification errors. Magn Reson Med 80:609-618, 2018. © 2018 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. © 2018 The Authors Magnetic Resonance

Scattering of Neutrons by Liquid Bromine; Diffusion des neutrons par le brome liquide; R; Dispersion de neutrones por bromo liquido

Energy Technology Data Exchange (ETDEWEB)

Coote, G E; Haywood, B C [Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada)

1963-01-15

Neutrons of 0.037 eV and 0.0088 eV were scattered from a thin sample of liquid bromine at room temperature, and the energy distributions of the scattered neutrons measured at angles from 10{sup o} to 160{sup o} by the time-of-flight method. The angular distribution confirms the results of a previous study by Caglioti. Spectra were expressed in the form of the ''scattering law'' S({alpha},{beta}) of Egelstaff and analysed to derive the generalized frequency distribution p({beta}) of atomic motions in the liquid. The function p({beta}) has a broad smooth peak centred at {beta}{approx}0.3, and shows no evidence for discrete levels in the measured range 0<{beta}< 0.8: the general shape of the curve supports the 'quasi-crystalline' picture of the liquid. Difficulty in the absolute normalization of p({beta}) is discussed. (author) [French] Des neutrons de 0,037 eV et 0,0088 eV ont ete dissuses par un echantillon mince de brome liquide a la temperature ambiante; on a mesure, par la methode du temps de vol, les distributions d'energies des neutrons diffuses, pour des angles compris entre 10{sup o} et 160{sup o}. La distribution angulaire confirme les resultats d'une etude anterieure faite par Caglioti. Les spectres ont ete exprimes d'apres la ''loi de dispersion'' S({alpha},{beta}) d'Egelstaff et analyses pour determiner la distribution generalisee des frequences p({beta}) des mouvements atomiques dans le liquide. La fonction p({beta}) comporte un pic large et a faible pente dont le centre est a {beta} {approx} 0,3 et ne presente aucune indication de niveaux discrets dans la gamme mesuree 0 < {beta} < 0,8; la forme generale de la courbe confirme l'image ''quasi cristalline'' du liquide. Les auteurs examinent les difficultes qui s'opposent a la normalisation absolue de p({beta}). (author) [Spanish] Los autores han estudiado la dispersion de neutrones de 0,037 eV y 0,0088 eV en una muestra de bromo liquido de espesor reducido, a temperatura ambiente. La distribucion

CITATION, 3-D Multigroup Diffusion with 1. Order Perturbation and Criticality Search

International Nuclear Information System (INIS)

Fowler, T.B.; Vondy, D.R.; Cunningham, G.W.

1995-01-01

1 - Description of problem or function: CITATION is designed to solve problems using the finite-difference representation of neutron diffusion theory, treating up to three space dimensions with arbitrary group-to-group scattering. X-y-z, theta-r-z, hexagonal-z, and trigonal-z geometries may be treated. Depletion problems may be solved and fuel managed for multi-cycle analysis. Extensive first-order perturbation results may be obtained given microscopic data and nuclide concentrations. Statics problems may be solved and perturbation results obtained with microscopic data. CITATION-2-3-VP2 is a vectorized version for FACOM VP-100 and VP-200 vector computers. 2 - Method of solution: Explicit, finite-difference approximations in space and time have been implemented. The neutron-flux-eigenvalue problems are solved by direct iteration to determine the multiplication factor or the nuclide densities required for a critical system. CITATION-2-3-VP2: Algorithms for the inner-outer iterative calculations are adapted to vector computers. The SLOR method, which is used in the original CITATION code, and the SOR method, which is adopted in the revised code, are vectorized by odd-even mesh ordering. 3 - Restrictions on the complexity of the problem: CITATION has been designed to attack problems which can be run in a reasonable amount of time. Storage of data is allocated dynamically to give the user flexibility in dimensioning. Typically, a finite-difference diffusion problem could have 200 depleting zones, 10,000 nuclide densities, and 30,000 space-energy point flux values

Pulsed neutron method for diffusion, slowing down, and reactivity measurements

International Nuclear Information System (INIS)

Sjoestrand, N.G.

1985-01-01

An outline is given on the principles of the pulsed neutron method for the determination of thermal neutron diffusion parameters, for slowing-down time measurements, and for reactivity determinations. The historical development is sketched from the breakthrough in the middle of the nineteen fifties and the usefulness and limitations of the method are discussed. The importance for the present understanding of neutron slowing-down, thermalization and diffusion are point out. Examples are given of its recent use for e.g. absorption cross section measurements and for the study of the properties of heterogeneous systems

Size dependent diffusive parameters and tensorial diffusion equations in neutronic models for optically small nuclear systems

International Nuclear Information System (INIS)

Premuda, F.

1983-01-01

Two lines in improved neutron diffusion theory extending the efficiency of finite-difference diffusion codes to the field of optically small systems, are here reviewed. The firs involves the nodal solution for tensorial diffusion equation in slab geometry and tensorial formulation in parallelepiped and cylindrical gemometry; the dependence of critical eigenvalue from small slab thicknesses is also analitically investigated and finally a regularized tensorial diffusion equation is derived for slab. The other line refer to diffusion models formally unchanged with respect to the classical one, but where new size-dependent RTGB definitions for diffusion parameters are adopted, requiring that they allow to reproduce, in diffusion approach, the terms of neutron transport global balance; the trascendental equation for the buckling, arising in slab, sphere and parallelepiped geometry from the above requirement, are reported and the sizedependence of the new diffusion coefficient and extrapolated end point is investigated

ACE Gene in Egyptian Ischemic Stroke Patients.

Science.gov (United States)

Mostafa, Magdy A; El-Nabiel, Lobna M; Fahmy, Nagia Aly; Aref, Hany; Shreef, Edrees; Abd El-Tawab, Fathy; Abdulghany, Osama M

2016-09-01

Angiotensin-1-converting enzyme (ACE) is a crucial player in vascular homeostasis and in the pathogenesis of atherosclerosis and hypertension. The present study was conducted to determine whether there is an association between the ACE insertion/deletion (I/D) polymorphism and ischemic stroke in Egyptian population. Also, we analyzed the ACE gene I/D polymorphism as a risk factor for small-vessel (SV) versus large-vessel (LV) disease. Sixty patients with ischemic stroke were included: 30 with SV disease and 30 with LV disease. In addition, a control group of 30 apparent healthy subjects were studied. Clinical assessment, computed tomography, magnetic resonance imaging brain, and genetic study using the polymerase chain reaction of ACE gene were done for all subjects. We found that the distribution of ACE gene polymorphism frequency was significantly different between the 3 groups. The DD genotype was far more common in stroke patients compared to controls. It was also significantly more common in each of the patient groups compared to controls but rather similar in the 2 patient groups with SV and LV diseases. We found that the ACE gene deletion/deletion genotype is common in Egyptian patients with non-cardioembolic ischemic stroke but does not appear to be specific neither to SV nor to LV disease. Copyright © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.

The importance of using the mixed neutron flux in activation analysis of D-3He fueled reactors

International Nuclear Information System (INIS)

Khater, H.Y.; Sawan, M.E.

1992-01-01

This paper reports on the D-D and D-T secondary reactions in D- 3 He reactors which provide the neutron source term for most of the radioactivity produced in the structure of the reactor. radionuclides are produced as a result of neutron interactions with their parent nuclides. The amount of activity produced by any radionuclide depends on the number of its parent atoms present at any given time. One approach to account for the activity induced by both neutron sources in any activation analysis is to add their individual contributions. Performing two separate calculations for the D-D and D-T neutron flux components and adding their contributions yields conservative results due to underestimating the destruction of the parent atoms. The overestimation is more pronounced for short and intermediate lived nuclides, long operation time, large neutron flux and large destruction cross section for the parent atoms. In the steel first wall of a typical d- 3 He reactor, adding the individual contributions of the tow neutron sources results in overestimating the activities produced by most of the radioactive isotopes of Ag, Lu, Ta, W and Re. After 30 years of reactor operation, the activity of 187 W, which is a major source of safety concern in case of an accident, is more than an order of magnitude higher than its value if the mixed neutron flux is used. The activity of 188 Re, which is an important source of offsite does in case of accidental release, is overestimated by more than a factor of two

Additive Construction with Mobile Emplacement (ACME) / Automated Construction of Expeditionary Structures (ACES) Materials Delivery System (MDS)

Science.gov (United States)

Mueller, R. P.; Townsend, I. I.; Tamasy, G. J.; Evers, C. J.; Sibille, L. J.; Edmunson, J. E.; Fiske, M. R.; Fikes, J. C.; Case, M.

2018-01-01

The purpose of the Automated Construction of Expeditionary Structures, Phase 3 (ACES 3) project is to incorporate the Liquid Goods Delivery System (LGDS) into the Dry Goods Delivery System (DGDS) structure to create an integrated and automated Materials Delivery System (MDS) for 3D printing structures with ordinary Portland cement (OPC) concrete. ACES 3 is a prototype for 3-D printing barracks for soldiers in forward bases, here on Earth. The LGDS supports ACES 3 by storing liquid materials, mixing recipe batches of liquid materials, and working with the Dry Goods Feed System (DGFS) previously developed for ACES 2, combining the materials that are eventually extruded out of the print nozzle. Automated Construction of Expeditionary Structures, Phase 3 (ACES 3) is a project led by the US Army Corps of Engineers (USACE) and supported by NASA. The equivalent 3D printing system for construction in space is designated Additive Construction with Mobile Emplacement (ACME) by NASA.

Measurement of neutron diffusion length in heavy concrete

International Nuclear Information System (INIS)

Krejci, D.

2007-04-01

Using an aluminium sampler filled with heavy concrete the neutron diffusion length was determined, measuring thermal and fast neutrons over the whole beam hole with various threshold detectors using gold samples. These calculations should describe the neutron distribution in the whole concrete shield of the reactor and contribute to the investigation of the activation of the concrete shield using reactor parameters like operating time, power and neutron flux. Instrumentation, activation and positioning of the samples in the beam hole of the TRIGA Mark II reactor are described. (nevyjel)

Phase correction for three-dimensional (3D) diffusion-weighted interleaved EPI using 3D multiplexed sensitivity encoding and reconstruction (3D-MUSER).

Science.gov (United States)

Chang, Hing-Chiu; Hui, Edward S; Chiu, Pui-Wai; Liu, Xiaoxi; Chen, Nan-Kuei

2018-05-01

Three-dimensional (3D) multiplexed sensitivity encoding and reconstruction (3D-MUSER) algorithm is proposed to reduce aliasing artifacts and signal corruption caused by inter-shot 3D phase variations in 3D diffusion-weighted echo planar imaging (DW-EPI). 3D-MUSER extends the original framework of multiplexed sensitivity encoding (MUSE) to a hybrid k-space-based reconstruction, thereby enabling the correction of inter-shot 3D phase variations. A 3D single-shot EPI navigator echo was used to measure inter-shot 3D phase variations. The performance of 3D-MUSER was evaluated by analyses of point-spread function (PSF), signal-to-noise ratio (SNR), and artifact levels. The efficacy of phase correction using 3D-MUSER for different slab thicknesses and b-values were investigated. Simulations showed that 3D-MUSER could eliminate artifacts because of through-slab phase variation and reduce noise amplification because of SENSE reconstruction. All aliasing artifacts and signal corruption in 3D interleaved DW-EPI acquired with different slab thicknesses and b-values were reduced by our new algorithm. A near-whole brain single-slab 3D DTI with 1.3-mm isotropic voxel acquired at 1.5T was successfully demonstrated. 3D phase correction for 3D interleaved DW-EPI data is made possible by 3D-MUSER, thereby improving feasible slab thickness and maximum feasible b-value. Magn Reson Med 79:2702-2712, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Small-angle neutron polarization for the 2H(d vector,n vector)3He reaction near Esub(d) = 8MeV

International Nuclear Information System (INIS)

Tornow, W.; Woye, W.; Mack, G.

1981-01-01

Considerable improvement in the quality of analyzing power experiments performed with polarized fast neutrons has been achieved during the last few years by using neutrons from the polarization transfer reaction 2 H(d vector,n vector) 3 He at a reaction angle of theta = 0 0 . To compromise in these experiments between intensity problems and finite geometry corrections, it is desirable in some instances to subtend a full-width angle Δtheta of 20 0 (lab) centered about theta = 0 0 . In order to investigate the suitability of this reaction as a source of polarized neutrons for cases where the scatterer is close to the neutron source, the neutron polarization of the reaction 2 H(d vector,n vector) 3 He has been studied with Δtheta of about 3 0 in 3 0 steps out to theta = 20 0 (lab). An incident deuteron energy near 8 MeV was chosen to yield outgoing neutrons at 11.0 MeV, a typical energy for neutron analyzing power experiments. It is found that the effective neutron polarization, a combination of the two polarizations measured when the direction of the deuteron polarization is inverted or flipped at the polarized ion source, is large and nearly constant for angles between theta = 0 0 and theta = 10 0 (lab). (orig.)

Diffusion approximation for modeling of 3-D radiation distributions

International Nuclear Information System (INIS)

Zardecki, A.; Gerstl, S.A.W.; De Kinder, R.E. Jr.

1985-01-01

A three-dimensional transport code DIF3D, based on the diffusion approximation, is used to model the spatial distribution of radiation energy arising from volumetric isotropic sources. Future work will be concerned with the determination of irradiances and modeling of realistic scenarios, relevant to the battlefield conditions. 8 refs., 4 figs

Association of ACE Gene I/D polymorphism with migraine in Kashmiri population.

Science.gov (United States)

Wani, Irfan Yousuf; Sheikh, Saleem; Shah, Zafar Amin; Pandith, Arshid A; Wani, Mushtaq; Asimi, Ravouf; Wani, Maqbool; Sheikh, Shahnawaz; Mehraj, Iqra

2016-01-01

Migraine is a complex, recurrent headache disorder that is one of the most common complaints in neurology practice. The role of various genes in its pathogenesis is being studied. We did this study to see whether an association exists between ACE gene I/D polymorphism and migraine in our region. The study included 100 patients diagnosed with migraine and 121 healthy controls. The study subject were age and gender matched. The analysis was based on Polymerase Chain Reaction (PCR) and included following steps: DNA extraction from blood, PCR and Restriction Fragment Length Polymorphism (RFLP). Out of 100 cases, 69 were females and 31 were males. Fifty-seven were having migraine without aura and 43 had migraine with aura. 45 of the cases had II polymorphism, 40 had ID polymorphism and 15 had DD polymorphism in ACE gene. We were not able to find a statistically significant association between ACE gene I/D polymorphism with migraine. The reason for difference in results between our study and other studies could be because of different ethnicity in study populations. So a continuous research is needed in this regard in order to find the genes and different polymorphism that increase the susceptibility of Kashmiri population to migraine.

Comparison of neutron fluxes obtained by 2-D and 3-D geometry with different shielding libraries in biological shield of the TRIGA MARK II reactor

International Nuclear Information System (INIS)

Bozic, M.; Zagar, T.; Ravnik, M.

2003-01-01

Neutron fluxes in different spatial locations in biological shield are obtained with TORT code (TORT-Three Dimensional Oak Ridge Discrete Ordinates Neutron/Photon Transport Code). Libraries used with TORT code were BUGLE-96 library (coupled library with 47 neutron groups and 20 gamma groups) and VITAMIN-B6 library (coupled library with 199 neutron groups and 42 gamma groups). BUGLE-96 library is derived from VITAMIN-B6 library. 2-D and 3-D models for homogeneous type of problem (without inserted beam port 4) and problem with asymmetry (non-homogeneous problem; inserted beam port 4, filled with different materials) were of interest for neutron flux calculation. The main purpose is to verify the possibility for using 2-D approximation model instead of large 3-D model in some calculations. Another purpose of this paper was to compare neutron spectral constants obtained from neutron fluxes (3-D model) determined with smaller BUGLE-96 library with new constants obtained from fluxes calculated with bigger VITAMIN-B6 library. These neutron spectral constants are used in isotopic calculation with SCALE code package (ORIGEN-S). In past only neutron spectral constants determined by neutron fluxes from BUGLE-96 library were used. Experimental results used for isotopic composition comparison are available from irradiation experiment with selected type of concrete and other materials in beam port 4 (irradiation channel 4) in TRIGA Mark II reactor. These experimental results were used as a benchmark in this paper. (author)

Differential Neutron Scattering from Hydrogenous Moderators; Diffusion Differentielle des Neutrons par des Ralentisseurs Hydrogenes; Differentsial'noe rasseyanie nejtronov iz vodorodosoderzhashchikh zamedlitelej; Dispersion Diferencial de Neutrones en Moderadores Hidrogenados

Energy Technology Data Exchange (ETDEWEB)

Beyster, J. R.; Young, J. C.; Neill, J. M.; Mowry, W. R. [General Atomic Division of General Dynamics Corporation, John Jay Hopkins Laboratory for Pure and Applied Science, San Diego, CA (United States)

1965-08-15

experiments, which are sensitive mainly to P{sub 0} scattering. In particular one may test the P{sub 1} scattering kernel appropriate to a given molecular model. Third, the transport cross-section may be calculated directly from the experiments for use in multigroup reactor analysis. (author) [French] On mesure par les methodes du temps de vol les sections efficaces differentielles de diffusion simple (d{sigma}/d {Omega}) pour les ralentisseurs usuels. On utilise des neutrons thermiques produits par une source puisee intense (accelerateur lineaire de la General Atomic) avec un parcours de vol de 12 m a l'extremite duquel est place un echantillon mince du ralentisseur a l*etude. En outre, on a egalement prevu un petit parcours de vol terminal pour les neutrons diffuses, entre l'echantillon et plusieurs detecteurs de neutrons entierement absorbants. Cette methode permet de mesurer simultanement la distribution angulaire de diffusion pour plus de 50 energies des neutrons incidents. Les intensites sont-elevees, le bruit de fond est faible et bien defini et on peut proceder a des mesures rapides pour tous les angles de diffusion compris entre 10 et 155 degres. Les auteurs presentent des mesures de la section efficace differentielle de diffusion pour le vanadium, H{sub 2}O, D{sub 2}O et ZrH. On a etudie le vanadium pour controler le dispositif experimental. On a fait des mesures avec H{sub 2}O pour diverses epaisseurs et orientations des echantillons en vue de les comparer aux calculs fondes sur divers modeles de diffusion par l'hydrogene lie et aux resultats obtenus par Springer et Reinsch. Toutes les mesures experimentales ont ete corrigees pour tenir compte des effets importants de la diffusion multiple dans les echantillons. Pour l'instant, on n'a pas observe experimentalement la variation accusee que fait prevoir le modele de diffusion de Nelkin lorsque l'energie des neutrons est d'environ 0,06 eV; ceci est du au fait que l'hypothese du rotateur unique inhibe a 0,06 eV n'a pas

Development of a D-D Neutron Generator

International Nuclear Information System (INIS)

Kim, In Jung; Jung, Hwa Dong; Park, Chang Su; Jung, Nam Suk; Jung, Soon Wook; Hwang, Y. S.; Choi, H. D.

2007-01-01

To enhance neutron yield, the ion source of the D-D neutron generator is replaced by a large current helicon plasma ion source. Current and energy of deuteron beam are increased, and hence neutron yield is enhanced. The maximum neutron yield is 2x10 8 n/s

TVEDIM, 2-D Homogeneous and Inhomogeneous Neutron Diffusion for X-Y, R-Z, R-Theta Geometry

International Nuclear Information System (INIS)

Kristiansen, G.K.

1987-01-01

1 - Nature of physical problem solved: The two-dimensional neutron diffusion equation (x-y, r-z, or r-theta geometry is solved, either in the inhomogeneous (source calculation) or the homogeneous form (K eff calculation or absorber adjustment). The boundary conditions specify each group current as a linear homogeneous function of the group fluxes (gamma matrix concept). For each material, the fission matrix is assumed to by dyadic. 2 - Method of solution: Finite difference formulation (5 point scheme, mesh corner variant) is used. Solution technique: multi-line SOR. Eigenvalue estimate by neutron balance

Time-of-flight and vector polarization analysis for diffuse neutron scattering

International Nuclear Information System (INIS)

Schweika, W.

2003-01-01

The potential of pulsed neutron sources for diffuse scattering including time-of-flight (TOF) and polarization analysis is discussed in comparison to the capabilities of the present instrument diffuse neutron scattering at the research center Juelich. We present first results of a new method for full polarization analysis using precessing neutron polarization. A proposal is made for a new type of instrument at pulsed sources, which allows for vector polarization analysis in TOF instruments with multi-detectors

Cement analysis using d + D neutrons

International Nuclear Information System (INIS)

Womble, Phillip C.; Paschal, Jon; Moore, Ryan

2005-01-01

In the cement industry, the primary concern is quality control. The earlier the cement industry can institute quality control upon their product, the more significant their savings in labor, energy and material. We are developing a prototype cement analyzer using pulsed neutrons from a d-D electronic neutron generator with the goal of ensuring quality control of cement in an on-line manner. By utilizing a low intensity d-D neutron source and a specially-designed moderator assembly, we are able to produce one of the safest neutron-based systems in the market. Also, this design includes some exciting new methods of data acquisition which may substantially reduce the final installation costs. In our proof-of-principle measurements, we were able to measure the primary components of cement (Al, Si, Ca and Fe) to limits required for the raw materials, the derived mixes and the clinkers utilizing this neutron generator

The PAI-1 4G/5G and ACE I/D polymorphisms and risk of recurrent pregnancy loss: a case-control study.

Science.gov (United States)

Kim, Jin Ju; Choi, Young Min; Lee, Sung Ki; Yang, Kwang Moon; Paik, Eun Chan; Jeong, Hyeon Jeong; Jun, Jong Kwan; Han, Ae Ra; Hong, Min A

2014-12-01

Thrombophilia has been postulated to be a contributor to the pathophysiology of recurrent pregnancy loss (RPL). We investigated the role of the plasminogen activator inhibitor type 1 (PAI-1) 4G/5G and angiotensin converting enzyme (ACE) I/D polymorphisms in Korean patients with RPL. Genotyping was performed using the TaqMan assay in 227 RPL patients and 304 controls. The genotype distributions of both polymorphisms in the RPL group did not differ from those of controls. Because the frequency of being homozygous for ACE D/D and the PAI-I 4G/4G combination has been reported to be significantly higher in RPL patients, this was also analyzed. However, no significant difference was noted; 3.1% of RPL patients had both ACE D/D and PAI-I 4G/4G, as did 4.9% of controls (P = 0.791). The current study suggests that both polymorphisms, either alone or in combination, are not major determinants of the development of RPL in Korean women. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Evaluation of whether the ACE gene I/D polymorphism constitutes a risk factor for chronic obstructive pulmonary disease in the Turkish population.

Science.gov (United States)

Ayada, C; Toru, U; Genç, O; Yerlikaya, A; Sahin, S; Turgut, S; Turgut, G

2014-12-12

Chronic obstructive pulmonary disease (COPD) is characterized by progressive airflow obstruction that occurs as a result of the normal inflammatory process to protect against harmful irritants and chemicals. Another physiological regulatory process, the renin angiotensin system (RAS), plays an important role in the pathology of many diseases. Angiotensin converting enzyme (ACE) is a key enzyme of RAS. We investigated the frequency of the ACE gene I/D polymorphism in patients with COPD in Turkey. This study was performed on 47 unrelated patients with COPD and 64 healthy subjects. DNA samples were isolated from peripheral blood, and ACE DNA was amplified by polymerase chain reaction. The frequencies of ACE genotypes were 27.7, 55.3, and 17% for DD, ID, and II in the COPD group, respectively, and 43.8, 43.8, and 12.4% in the control group. There was no statistically significant difference between groups (X(2) = 3.078; df = 2; P = 0.220). The distributions of ACE gene D alleles were 38.2% (N = 52) in the COPD group and 61.8% (N = 84) in the control group; and those of I alleles were 48.8% (N = 42) in the COPD group and 51.2% (N = 44) in the control group. There was no statistically significant difference between groups for allele frequency (X(2) = 2.419; df = 2; P = 0.120). We believe these results can be useful for large-scale population genetic research considering the frequency of the ACE gene variation in COPD patients in the Turkish population.

ACE I/D Gene Polymorphism Can't Predict the Steroid Responsiveness in Asian Children with Idiopathic Nephrotic Syndrome: A Meta-Analysis

Science.gov (United States)

Su, Li-Na; Lei, Feng-Ying; Huang, Wei-Fang; Zhao, Yan-Jun

2011-01-01

Background The results from the published studies on the association between angiotensin-converting enzyme (ACE) insertion/deletion (I/D) gene polymorphism and the treatment response to steroid in Asian children with idiopathic nephrotic syndrome (INS) is still conflicting. This meta-analysis was performed to evaluate the relation between ACE I/D gene polymorphism and treatment response to steroid in Asian children and to explore whether ACE D allele or DD genotype could become a predictive marker for steroid responsiveness. Methodology/Principal Findings Association studies were identified from the databases of PubMed, Embase, Cochrane Library and CBM-disc (China Biological Medicine Database) as of September 1, 2010, and eligible investigations were synthesized using meta-analysis method. Five investigations were identified for the analysis of association between ACE I/D gene polymorphism and steroid-resistant nephrotic syndrome (SRNS) risk in Asian children and seven studies were included to explore the relationship between ACE I/D gene polymorphism and steroid-sensitive nephrotic syndrome (SSNS) susceptibility. Five investigations were recruited to explore the difference of ACE I/D gene distribution between SRNS and SSNS. There was no a markedly association between D allele or DD genotype and SRNS susceptibility or SSNS risk, and the gene distribution differences of ACE between SRNS and SSNS were not statistically significant. II genotype might play a positive role against SRNS onset but not for SSNS (OR = 0.51, P = 0.02; OR = 0.95, P = 0.85; respectively), however, the result for the association of II genotype with SRNS risk was not stable. Conclusions/Significance Our results indicate that D allele or DD homozygous can't become a significant genetic molecular marker to predict the treatment response to steroid in Asian children with INS. PMID:21611163

DD Genotype of ACE I/D Polymorphism Might Confer Protection against Dental Caries in Polish Children.

Science.gov (United States)

Olszowski, Tomasz; Adler, Grażyna; Janiszewska-Olszowska, Joanna; Safranow, Krzysztof; Chlubek, Dariusz

2015-01-01

The aim of the study was to examine the frequencies of the genotypes and alleles of ACE insertion/deletion (I/D) polymorphism and their association with dental caries in a sample of Polish children. The study subjects were 120 children with dental caries experience (cases) and 41 caries-free individuals (controls). The genotyping was performed using polymerase chain reaction. The genotype distributions of ACE I/D polymorphism were not statistically different between carious and control children. However, we found a borderline overrepresentation of the II + ID genotypes versus the DD genotype in the carious compared to the control group (69.2% and 51.2%, respectively, p = 0.057). Logistic regression analysis adjusted for age and sex revealed that I allele carriage was a significant predictor of dental caries susceptibility (OR = 2.14, 95% CI = 1.02-4.49, p = 0.041). In conclusion, the DD genotype of ACE I/D polymorphism might be protective against dental caries in Polish children. © 2015 S. Karger AG, Basel.

The fortran programme for the calculation of the absorption and double scattering corrections in cross-section measurements with fast neutrons using the monte Carlo method (1963); Programme fortran pour le calcul des corrections d'absorption et de double diffusion dans les mesures de sections efficaces pour les neutrons rapides par la methode de monte-carlo (1963)

Energy Technology Data Exchange (ETDEWEB)

Fernandez, B [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-07-01

A calculation for double scattering and absorption corrections in fast neutron scattering experiments using Monte-Carlo method is given. Application to cylindrical target is presented in FORTRAN symbolic language. (author) [French] Un calcul des corrections de double diffusion et d'absorption dans les experiences de diffusion de neutrons rapides par la methode de Monte-Carlo est presente. L'application au cas d'une cible cylindrique est traitee en langage symbolique FORTRAN. (auteur)

HEXNOD23, 2-D, 3-D Coarse Mesh Solution of Steady State Diffusion Equation in Hexagonal Geometry

International Nuclear Information System (INIS)

Grundmann, Ulrich

1986-01-01

1 - Description of program or function: Two- or three dimensional coarse mesh solution of steady state two group neutron diffusion equation in arrays of regular hexagons or hexagonal subassemblies. 2 - Method of solution: The neutron flux in a hexagonal node is expanded in a series of Bessel functions in the hexagonal plane. Polynomials up to the 4. order are used for the approximation of neutron flux in axial direction of three dimensional cases. Resulting relations between node averaged fluxes and mean partial currents of node faces in connection with the neutron balance of nodes are used to calculate the eigenvalue Keff, mean fluxes and mean powers of nodes. The iterations process is divided into inner and outer iterations. The iterations are accelerated by Ljusternik and Tschebyscheff extrapolation schemes. The power densities in the nodes and subassembly powers are computed for given reactor power in three dimensional cases. 30 degree reflectional, 60 and 120 degree rotational core symmetry and the whole core can be treated. 3 - Restrictions on the complexity of the problem: If the problem size designated by LIAR and LRAR exceeds 3000 and 50000 respectively, the lengths of the working array MIAR and MRAR in the main program can be increased. External sources are not permitted

Neutron Fluence Evaluation of Reactor Internal Structure Using 3D Transport Calculation Code, RAPTOR-M3G

International Nuclear Information System (INIS)

Maeng, YoungJae; Lim, MiJoung; Kim, KyungSik; Cho, YoungKi; Yoo, ChoonSung; Kim, ByoungChul

2015-01-01

Age-related degradation mechanisms are including the irradiation-assisted stress corrosion cracking(IASCC), void swelling, stress relaxation, fatigue, and etc. A lot of Baffle Former Bolts(BFBs) was installed at the former plate ends between baffle and barrel structure. These would undergo severe experiences, which are high temperature and pressure, bypass water flow and neutron exposure and have some radioactive limitation in inspecting their integrity. The objectives of this paper is to evaluate fast neutron fluence(n/cm 2 , E>1.0MeV) for PWR internals using 3D transport calculation code, RAPTOR-M3G, and to figure out a strategy to manage the effects of aging in PWR internals. One of age-related degradation mechanisms, IASCC, which is affected by fast neutron exposure rate, has been currently issued for PWR internals and has 2 x 10 21 (n/cm 2 ) of the threshold value by MRP-175. Because a lot of BFBs was installed around the internal components, closer inspections are required. As part of an aging management for Kori unit 2, 3D transport calculation code, RAPTOR-M3G, was applied for determining fast neutron fluence at baffle, barrel and former plates regions. As a result, the fast neutron fluence exceeds the screening or threshold values of IASCC in all of baffle, barrel and former plate region. And the most significant region is the baffle because it is located closest to the core. In addition, some regions including former plate tend to be more damaged because of less moderate ability than water. In conclusion, Ice's has been progressed for PWR internals of Kori unit 2. Several regions of internal components were damaged by fast neutron exposure and increase in size as time goes by

ACE-FTS version 3.0 data set: validation and data processing update

Directory of Open Access Journals (Sweden)

Claire Waymark

2014-01-01

Full Text Available On 12 August 2003, the Canadian-led Atmospheric Chemistry Experiment (ACE was launched into a 74° inclination orbit at 650 km with the mission objective to measure atmospheric composition using infrared and UV-visible spectroscopy (Bernath et al. 2005. The ACE mission consists of two main instruments, ACE-FTS and MAESTRO (McElroy et al. 2007, which are being used to investigate the chemistry and dynamics of the Earth’s atmosphere.  Here, we focus on the high resolution (0.02 cm-1 infrared Fourier Transform Spectrometer, ACE-FTS, that measures in the 750-4400 cm-1 (2.2 to 13.3 µm spectral region.  This instrument has been making regular solar occultation observations for more than nine years.  The current ACE-FTS data version (version 3.0 provides profiles of temperature and volume mixing ratios (VMRs of more than 30 atmospheric trace gas species, as well as 20 subsidiary isotopologues of the most abundant trace atmospheric constituents over a latitude range of ~85°N to ~85°S.  This letter describes the current data version and recent validation comparisons and provides a description of our planned updates for the ACE-FTS data set. [...

Association of ACE gene A2350G and I/D polymorphisms with essential hypertension in the northernmost province of China.

Science.gov (United States)

Sun, Feifei; He, Ning; Zhang, Keyong; Wu, Nan; Zhao, Jingbo; Qiu, Changchun

2018-01-01

Angiotensin converting enzyme (ACE) gene, as a strong candidate gene for essential hypertension(EH), has been extensively studied. In this study, we carried out a population-based case-control study to explore whether ACE gene I/D and A2350G polymorphisms could consider to be risk factors for EH. A total of 2040 subjeces were recruited from Chinese Han in this study, out of which 1010 were cases and 1030 were normotensive individuals. ACE gene A2350G and I/D polymorphisms were amplified by polymerase chain reaction (PCR) and A2350G polymorphism was detected after restriction enzyme digestion with BstuI. Besides, we choosed 10% samples randomly sequencing to verify the accuracy of results. Genotype and allele frequencies distribution of I/D and A2350G in EH and control groups were significantly different. After grouped by sex or age, there were still statistical significances for two polymorphisms. In dominant and recessive model of A2350G, we found significant differences between two groups, respectively. For ACE I/D polymorphism, we observed that the existence of dramatical difference in dominant model between two groups, while in recessive model, marginally significant difference was found. Among the four haplotypes composed by ACE gene A2350G and I/D, haplotype G-D reached the statistical significance in two groups, and exhibited to be a risk factor for the development of EH, whose P ACE gene A2350G and I/D polymorphisms were associated with increasing the risk of suffering from EH in the northernmost province of China individuals, with D allele and G allele individuals had a higher risk of EH(OR = 1.443, 95%CI = 1.273-1.636 and OR = 1.481, 95%CI = 1.303-1.684).

Twin-domain size and bulk oxygen in-diffusion kinetics of YBa 2Cu 3O 6+x studied by neutron powder diffraction and gas volumetry

Science.gov (United States)

Poulsen, H. F.; Andersen, N. H.; Lebech, B.

1991-02-01

We report experimental results of twin-domain size and bulk oxygen in-diffusion kinetics of YBa 2Cu 3O 6+ x, which supplement a previous and simultaneous study of the structural phase diagram and oxygen equilibrium partial pressure. Analysis of neutron powder diffraction peak broadening show features which are identified to result from temperature independent twin-domain formation in to different orthorhombic phases with domain sizes and 250 and 350Å, respectively. The oxygen in-diffusion flow shows simple relaxation type behaviour J=J 0 exp( {-t}/{τ}) despite a rather broad particle size distribution. At higher temperatures, τ is activated with activation energies 0.55 and 0.25 eV in the tetragonal and orthorhombic phases, respectively. Comparison between twin-domain sizes and bulk oxygen in-diffusion time constants indicates that the twin-domain boundaries may contribute to the effective bulk oxygen in-diffusion. All our results may be interpreted in terms of the 2D ASYNNNI model description of the oxygen basal plane ordering, and they suggest that recent first principles interaction parameters should be modified.

Determination of neutron buildup factor using analytical solution of one-dimensional neutron diffusion equation in cylindrical geometry

Energy Technology Data Exchange (ETDEWEB)

Fernandes, Julio Cesar L.; Vilhena, Marco Tullio, E-mail: julio.lombaldo@ufrgs.b, E-mail: vilhena@pq.cnpq.b [Universidade Federal do Rio Grande do Sul (DMPA/UFRGS), Porto Alegre, RS (Brazil). Dept. de Matematica Pura e Aplicada. Programa de Pos Graduacao em Matematica Aplicada; Borges, Volnei; Bodmann, Bardo Ernest, E-mail: bardo.bodmann@ufrgs.b, E-mail: borges@ufrgs.b [Universidade Federal do Rio Grande do Sul (PROMEC/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica

2011-07-01

The principal idea of this work, consist on formulate an analytical method to solved problems for diffusion of neutrons with isotropic scattering in one-dimensional cylindrical geometry. In this area were develop many works that study the same problem in different system of coordinates as well as cartesian system, nevertheless using numerical methods to solve the shielding problem. In view of good results in this works, we starting with the idea that we can represent a source in the origin of the cylindrical system by a Delta Dirac distribution, we describe the physical modeling and solved the neutron diffusion equation inside of cylinder of radius R. For the case of transport equation, the formulation of discrete ordinates S{sub N} consists in discretize the angular variables in N directions and in using a quadrature angular set for approximate the sources of scattering, where the Diffusion equation consist on S{sub 2} approximated transport equation in discrete ordinates. We solved the neutron diffusion equation with an analytical form by the finite Hankel transform. Was presented also the build-up factor for the case that we have neutron flux inside the cylinder. (author)

Determination of neutron buildup factor using analytical solution of one-dimensional neutron diffusion equation in cylindrical geometry

International Nuclear Information System (INIS)

Fernandes, Julio Cesar L.; Vilhena, Marco Tullio; Borges, Volnei; Bodmann, Bardo Ernest

2011-01-01

The principal idea of this work, consist on formulate an analytical method to solved problems for diffusion of neutrons with isotropic scattering in one-dimensional cylindrical geometry. In this area were develop many works that study the same problem in different system of coordinates as well as cartesian system, nevertheless using numerical methods to solve the shielding problem. In view of good results in this works, we starting with the idea that we can represent a source in the origin of the cylindrical system by a Delta Dirac distribution, we describe the physical modeling and solved the neutron diffusion equation inside of cylinder of radius R. For the case of transport equation, the formulation of discrete ordinates S N consists in discretize the angular variables in N directions and in using a quadrature angular set for approximate the sources of scattering, where the Diffusion equation consist on S 2 approximated transport equation in discrete ordinates. We solved the neutron diffusion equation with an analytical form by the finite Hankel transform. Was presented also the build-up factor for the case that we have neutron flux inside the cylinder. (author)

The Metabolic Response of Skeletal Muscle to Endurance Exercise Is Modified by the ACE-I/D Gene Polymorphism and Training State

Directory of Open Access Journals (Sweden)

Paola Valdivieso

2017-12-01

Full Text Available The insertion/deletion polymorphism in the gene for the regulator of vascular tone, angiotensin-converting enzyme (ACE, is the prototype of a genetic influence on physical fitness and this involves an influence on capillary supply lines and dependent aerobic metabolism in skeletal muscle. The respective interaction of ACE-I/D genotype and training status on local metabolic and angiogenic reactions in exercised muscle is not known. Toward this end we characterized the metabolomic and angiogenic response in knee extensor muscle, m. vastus lateralis, in 18 untrained and 34 endurance-trained (physically active, V˙O2max > 50 mL min−1 kg−1 white British men to an exhaustive bout of one-legged cycling exercise. We hypothesized that training status and ACE-I/D genotype affect supply-related muscle characteristics of exercise performance in correspondence to ACE expression and angiotensin 2 levels. ACE-I/D genotype and training status developed an interaction effect on the cross-sectional area (CSA of m. vastus lateralis and mean CSA of slow type fibers, which correlated with peak power output (r ≥ 0.44. Genotype × training interactions in muscle also resolved for exercise-induced alterations of 22 metabolites, 8 lipids, glycogen concentration (p = 0.016, ACE transcript levels (p = 0.037, and by trend for the pro-angiogenic factor tenascin-C post exercise (p = 0.064. Capillary density (p = 0.001, capillary-to-fiber ratio (p = 0.010, systolic blood pressure (p = 0.014, and exercise-induced alterations in the pro-angiogenic protein VEGF (p = 0.043 depended on the ACE-I/D genotype alone. Our observations indicate that variability in aerobic performance in the studied subjects was in part reflected by an ACE-I/D-genotype-modulated metabolic phenotype of a major locomotor muscle. Repeated endurance exercise appeared to override this genetic influence in skeletal muscle by altering the ACE-related metabolic response and molecular aspects of the

The Metabolic Response of Skeletal Muscle to Endurance Exercise Is Modified by the ACE-I/D Gene Polymorphism and Training State.

Science.gov (United States)

Valdivieso, Paola; Vaughan, David; Laczko, Endre; Brogioli, Michael; Waldron, Sarah; Rittweger, Jörn; Flück, Martin

2017-01-01

The insertion/deletion polymorphism in the gene for the regulator of vascular tone, angiotensin-converting enzyme (ACE), is the prototype of a genetic influence on physical fitness and this involves an influence on capillary supply lines and dependent aerobic metabolism in skeletal muscle. The respective interaction of ACE-I/D genotype and training status on local metabolic and angiogenic reactions in exercised muscle is not known. Toward this end we characterized the metabolomic and angiogenic response in knee extensor muscle, m. vastus lateralis , in 18 untrained and 34 endurance-trained (physically active, [Formula: see text]O2max > 50 mL min -1 kg -1 ) white British men to an exhaustive bout of one-legged cycling exercise. We hypothesized that training status and ACE-I/D genotype affect supply-related muscle characteristics of exercise performance in correspondence to ACE expression and angiotensin 2 levels. ACE-I/D genotype and training status developed an interaction effect on the cross-sectional area (CSA) of m. vastus lateralis and mean CSA of slow type fibers, which correlated with peak power output ( r ≥ 0.44). Genotype × training interactions in muscle also resolved for exercise-induced alterations of 22 metabolites, 8 lipids, glycogen concentration ( p = 0.016), ACE transcript levels ( p = 0.037), and by trend for the pro-angiogenic factor tenascin-C post exercise ( p = 0.064). Capillary density ( p = 0.001), capillary-to-fiber ratio ( p = 0.010), systolic blood pressure ( p = 0.014), and exercise-induced alterations in the pro-angiogenic protein VEGF ( p = 0.043) depended on the ACE-I/D genotype alone. Our observations indicate that variability in aerobic performance in the studied subjects was in part reflected by an ACE-I/D-genotype-modulated metabolic phenotype of a major locomotor muscle. Repeated endurance exercise appeared to override this genetic influence in skeletal muscle by altering the ACE-related metabolic response and molecular aspects

Sensitivity analysis of the Galerkin finite element method neutron diffusion solver to the shape of the elements

Energy Technology Data Exchange (ETDEWEB)

Hosseini, Seyed Abolfaz [Dept. of Energy Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of)

2017-02-15

The purpose of the present study is the presentation of the appropriate element and shape function in the solution of the neutron diffusion equation in two-dimensional (2D) geometries. To this end, the multigroup neutron diffusion equation is solved using the Galerkin finite element method in both rectangular and hexagonal reactor cores. The spatial discretization of the equation is performed using unstructured triangular and quadrilateral finite elements. Calculations are performed using both linear and quadratic approximations of shape function in the Galerkin finite element method, based on which results are compared. Using the power iteration method, the neutron flux distributions with the corresponding eigenvalue are obtained. The results are then validated against the valid results for IAEA-2D and BIBLIS-2D benchmark problems. To investigate the dependency of the results to the type and number of the elements, and shape function order, a sensitivity analysis of the calculations to the mentioned parameters is performed. It is shown that the triangular elements and second order of the shape function in each element give the best results in comparison to the other states.

The KASY synthesis programme for the approximative solution of the 3-dimensional neutron diffusion equation

International Nuclear Information System (INIS)

Buckel, G.; Wouters, R. de; Pilate, S.

1977-01-01

The synthesis code KASY for an approximate solution of the three-dimensional neutron diffusion equation is described; the state of the art as well as envisaged program extensions and the application to tasks from the field of reactor designing are dealt with. (RW) [de

Fast solution of neutron diffusion problem by reduced basis finite element method

International Nuclear Information System (INIS)

Chunyu, Zhang; Gong, Chen

2018-01-01

Highlights: •An extremely efficient method is proposed to solve the neutron diffusion equation with varying the cross sections. •Three orders of speedup is achieved for IAEA benchmark problems. •The method may open a new possibility of efficient high-fidelity modeling of large scale problems in nuclear engineering. -- Abstract: For the important applications which need carry out many times of neutron diffusion calculations such as the fuel depletion analysis and the neutronics-thermohydraulics coupling analysis, fast and accurate solutions of the neutron diffusion equation are demanding but necessary. In the present work, the certified reduced basis finite element method is proposed and implemented to solve the generalized eigenvalue problems of neutron diffusion with variable cross sections. The order reduced model is built upon high-fidelity finite element approximations during the offline stage. During the online stage, both the k eff and the spatical distribution of neutron flux can be obtained very efficiently for any given set of cross sections. Numerical tests show that a speedup of around 1100 is achieved for the IAEA two-dimensional PWR benchmark problem and a speedup of around 3400 is achieved for the three-dimensional counterpart with the fission cross-sections, the absorption cross-sections and the scattering cross-sections treated as parameters.

Association of ACTN3 R577X but not ACE I/D gene variants with elite rugby union player status and playing position

OpenAIRE

Heffernan, S. M.; Kilduff, L. P.; Erskine, R. M.; Day, S. H.; McPhee, J. S.; McMahon, G. E.; Stebbings, G. K.; Neale, J. P. H.; Lockey, S. J.; Ribbans, W. J.; Cook, C. J.; Vance, B.; Raleigh, S. M.; Roberts, C.; Bennett, M. A.

2016-01-01

We aimed to quantify the ACE I/D and ACTN3 R577X (rs1815739) genetic variants in elite rugby athletes (rugby union and league) and compare genotype frequencies to controls and between playing positions. The rugby athlete cohort consisted of 507 Caucasian men, including 431 rugby union athletes that for some analyses were divided into backs and forwards and into specific positional groups: front five, back row, half backs, centers, and back three. Controls were 710 Caucasian men and women. Rea...

Pulsed neutron determination of anisotropic diffusion constants in multi-layered slabs

International Nuclear Information System (INIS)

Sri Ram, K.

1978-01-01

Anisotropic neutron diffusion parameters for graphite and plexiglas slab assemblies were calculated using one-dimensional discrete ordinates code ANISN, and also Case's eigenfunction expansion technique as suggested by Leonard. These calculated values were checked with the pulsed neutron experimental results as well as simple diffusion theory calculations of Spinrad. Relatively little experimental work has been done with heterogeneous assemblies which do not contain voids. The present comparison shows that the experimental results agree well with transport theory calculations. It appears from the results and inter-comparison of this work in simple geometries, that the pulsed neutron method can yield accurate experimental anisotropic diffusion constants, and can therefore be applied to more complicated geometries which may be difficult to calculate. (author)

Enhanced finite difference scheme for the neutron diffusion equation using the importance function

International Nuclear Information System (INIS)

Vagheian, Mehran; Vosoughi, Naser; Gharib, Morteza

2016-01-01

Highlights: • An enhanced finite difference scheme for the neutron diffusion equation is proposed. • A seven-step algorithm is considered based on the importance function. • Mesh points are distributed through entire reactor core with respect to the importance function. • The results all proved that the proposed algorithm is highly efficient. - Abstract: Mesh point positions in Finite Difference Method (FDM) of discretization for the neutron diffusion equation can remarkably affect the averaged neutron fluxes as well as the effective multiplication factor. In this study, by aid of improving the mesh point positions, an enhanced finite difference scheme for the neutron diffusion equation is proposed based on the neutron importance function. In order to determine the neutron importance function, the adjoint (backward) neutron diffusion calculations are performed in the same procedure as for the forward calculations. Considering the neutron importance function, the mesh points can be improved through the entire reactor core. Accordingly, in regions with greater neutron importance, density of mesh elements is higher than that in regions with less importance. The forward calculations are then performed for both of the uniform and improved non-uniform mesh point distributions and the results (the neutron fluxes along with the corresponding eigenvalues) for the two cases are compared with each other. The results are benchmarked against the reference values (with fine meshes) for Kang and Rod Bundle BWR benchmark problems. These benchmark cases revealed that the improved non-uniform mesh point distribution is highly efficient.

Association of AGTR1 (A1166C and ACE (I/D Polymorphisms with Breast Cancer Risk in North Indian Population

Directory of Open Access Journals (Sweden)

Anukriti Singh

2018-04-01

Full Text Available Renin angiotensin system (RAS comprising Angiotensin converting enzyme (ACE, Angiotensin II (Ang II and its receptor Angiotensin II receptor type I (AGTR1, plays a critical role in several diseases including cancer. A single nucleotide polymorphism (SNP A1166C located in 3′ untranslated region (UTR of AGTR1 and an insertion/deletion (I/D polymorphism present in intron 16 of ACE gene have been associated with many diseases, but their association with Breast cancer (BCa is still debatable. Here, we for the first time investigated the association of these polymorphisms in a North Indian BCa cohort including 161 patients and 152 healthy women. The polymorphisms were evaluated by polymerase chain reaction (PCR and restriction fragment length polymorphism (RFLP respectively. The association between these polymorphisms and BCa risk was estimated by calculating Odds Ratio (OR and chi-square (χ2 test. The DD genotype/D allele of ACE (I/D polymorphism and “AC and CC” genotype/C allele of AGTR1 (A1166C polymorphism were associated with higher risk of BCa when evaluated independently. Furthermore, interaction analysis of “AC and CC” and DD genotype and combination of “C and D” alleles of both polymorphisms revealed significantly greater BCa risk than that observed independently. Conclusively, women harboring “AC or CC” genotype/C allele for AGTR1 (A1166C polymorphism and DD genotype/D allele for ACE (I/D polymorphisms have a predisposition to develop more aggressive disease with advanced staging and larger tumor size. Our study indicates importance of genetic screening based on these polymorphisms for women, who may have higher risk of BCa.

Prototype coupling of the CFD software ansys CFX with the 3D neutron kinetic core model DYN3D - 249

International Nuclear Information System (INIS)

Kliem, S.; Rohde, U.; Schutze, J.; Frank, Th.

2010-01-01

The CFD code ANSYS CFX has been coupled with the neutron-kinetic core model DYN3D. ANSYS CFX calculates the fluid dynamics and related transport phenomena in the reactor's coolant and provides the corresponding data to DYN3D. In the fluid flow simulation of the coolant, the core itself is modeled within the porous body approach. DYN3D calculates the neutron kinetics and the fuel behavior including the heat transfer to the coolant. The physical data interface between the codes is the volumetric heat release rate into the coolant. In the prototype that is currently available, the coupling is restricted to single-phase flow problems. In the time domain an explicit coupling of the codes has been implemented so far. Steady-state and transient verification calculations for a small-size test problem confirm the correctness of the implementation of the prototype coupling. This test problem was a mini-core consisting of nine real-size fuel assemblies. Comparison was performed with the DYN3D standalone code. In the steady state, the effective multiplication factor obtained by the ANSYS CFX/DYN3D codes shows a deviation of 9.8 pcm from the DYN3D stand-alone solution. This difference can be attributed to the use of different water property packages in the two codes. The transient test case simulated the withdrawal of the control rod from the central fuel assembly at hot zero power. Power increase during the introduction of positive reactivity and power reduction due to fuel temperature increase are calculated in the same manner by the coupled and the stand-alone codes. The maximum values reached during the power rise differ by about 1 MW at a power level of 50 MW. Beside the different water property packages, these differences are caused by the use of different flow solvers. (authors)

Implications of ACE (I/D) Gene Variants to the Genetic Susceptibility of Coronary Artery Disease in Asian Indians.

Science.gov (United States)

Bhatti, G K; Bhatti, J S; Vijayvergiya, R; Singh, B

2017-06-01

Angiotensin-1-converting enzyme (ACE) gene has established substantial attention in the recent years as a candidate gene for hypertension, cardiovascular diseases and type 2 diabetes. The aim of the present study was to investigate the association of ACE (I/D) polymorphism with coronary artery disease (CAD) in a north Indian population. A total of 662 subjects (330 CAD patients and 332 healthy controls) were examined for association of ACE gene (I/D) polymorphism and environmental risk factors. The mean age of the CAD patients and control subjects was 60.53 ± 8.6 years and 56.55 ± 7.7 years, respectively ( p  = 0.000). Anthropometric and demographic data showed BMI values significantly higher among CAD patients and control subjects (26.98 ± 4.9 vs 24.04 ± 4.7, p  = 0.000). We observed pronounced central obesity in both CAD patients and controls, even at the lowest BMI values (ACE gene. In conclusion, DD genotype of ACE gene may be associated with increased risk of CAD in Asian Indian population.

Development of a 3D consistent 1D neutronics model for reactor core simulation

International Nuclear Information System (INIS)

Lee, Ki Bog; Joo, Han Gyu; Cho, Byung Oh; Zee, Sung Quun

2001-02-01

In this report a 3D consistent 1D model based on nonlinear analytic nodal method is developed to reproduce the 3D results. During the derivation, the current conservation factor (CCF) is introduced which guarantees the same axial neutron currents obtained from the 1D equation as the 3D reference values. Furthermore in order to properly use 1D group constants, a new 1D group constants representation scheme employing tables for the fuel temperature, moderator density and boron concentration is developed and functionalized for the control rod tip position. To test the 1D kinetics model with CCF, several steady state and transient calculations were performed and compared with 3D reference values. The errors of K-eff values were reduced about one tenth when using CCF without significant computational overhead. And the errors of power distribution were decreased to the range of one fifth or tenth at steady state calculation. The 1D kinetics model with CCF and the 1D group constant functionalization employing tables as a function of control rod tip position can provide preciser results at the steady state and transient calculation. Thus it is expected that the 1D kinetics model derived in this report can be used in the safety analysis, reactor real time simulation coupled with system analysis code, operator support system etc.

Contribution to the experimental study of the critical scattering of cold neutrons in iron; Contriiution a l'etude experimentale de la diffusion critique des neutrons froids par le fer

Energy Technology Data Exchange (ETDEWEB)

Konstantinovic, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-03-15

The aim of the present work is a study of magnetic fluctuations which are produced in iron in the neighbourhood of the Curie temperature, by neutron scattering. We start by briefly recalling the theory of scattering of neutrons by magnetic substances and Landau's theory of second order phase transitions which enables one to derive the magnetic cross section near the Curie temperature. Following this is a description of the experimental apparatus after which we present the experimental results. The analysis of the results confirms the four-third law obeyed by the magnetic susceptibility near the Curie point, predicted by recent theories based on the Heisenberg model. However, the analysis reveals a non-zero relaxation time for the magnetic fluctuations at the Curie point, which is in disagreement with theoretical conclusions. (author) [French] L'objet du present travail est l'etude des fluctuations d'aimantation qui prennent naissance dans le fer au voisinage de sa temperature de Curie par la diffusion des neutrons. Nous commencons par rappeler brievement les generalites sur la diffusion des neutrons par les substances magnetiques et la theorie de Landau des transitions de phase du second ordre qui permet de deriver une expression de la section efficace magnetique pres de la temperature de Curie. Ensuite, apres la description du dispositif experimental, nous presentons les resultats experimentaux. L'analyse de ces resultats confirme les theories recentes suivant le modele d'Heisenberg en ce qui concerne la 'loi en 4/3' de la susceptibilite magnetique au voisinage du point de Curie; mais par ailleurs elle revele l'existence d'un temps de relaxation des fluctuations d'aimantation non nul en ce point, ce qui est en desaccord avec les previsions theoriques actuelles. (auteur)

Impact of I/D polymorphism of angiotensin-converting enzyme (ACE) gene on myocardial infarction susceptibility among young Moroccan patients.

Science.gov (United States)

Hmimech, Wiam; Idrissi, Hind Hassani; Diakite, Brehima; Korchi, Farah; Baghdadi, Dalila; Tahri Joutey Hassani Idrissi, Hind; Haboub, Meriem; Habbal, Rachida; Nadifi, Sellama

2017-12-21

Our case-control study aimed to access the potential association of insertion/deletion (I/D) ACE (angiotensin converting enzyme) gene polymorphism with myocardial infarction (MI) risk of occurrence among a sample of Moroccan patients, especially young ones. Distribution of I/D ACE gene variant among cases vs controls, showed that healthy controls carried out higher frequency of wild type allele I compared to cases (23.5% vs 21.79% respectively), when cases were carrying higher frequency of mutant allele D (78.21% vs 76.5% for controls). Patients were-after this- divided into two groups of  55 years of age, to investigate whether or not younger patients carried out higher frequency of the mutant allele D, than older ones. As expected, ACE polymorphism may be associated with MI occurrence among younger patients (< 45 years of age).

Prompt-gamma neutron activation analysis system design: Effects of D-T versus D-D neutron generator source selection

Science.gov (United States)

Prompt-gamma neutron activation (PGNA) analysis is used for the non-invasive measurement of human body composition. Advancements in portable, compact neutron generator design have made those devices attractive as neutron sources. Two distinct generators are available: D-D with 2.5 MeV and D-T with...

Cross sections for d-{sup 3}H neutron interactions with samarium isotopes

Energy Technology Data Exchange (ETDEWEB)

Luo, Junhua; He, Long [Hexi Univ., Zhangye (China). School of Physics and Electromechanical Engineering; Wu, Chunlei; Jiang, Li [Chinese Academy of Engineering Physics, Mianyang (China). Inst. of Nuclear Physics and Chemistry

2016-11-01

The cross sections for (n,x) reactions on samarium isotopes were measured at (d-T) neutron energies of 13.5 and 14.8 MeV with the activation technique. Samples were activated along with Nb and Al monitor foils to determine the incident neutron flux. Theoretical calculations of excitation functions were performed using the nuclear model codes TALYS-1.6 and EMPIRE-3.2 Malta with default parameters, at neutron energies varying from the reaction threshold to 20 MeV. The results were discussed and compared with experimental data found in the literature. At neutron energies 13.5 and 14.8 MeV, the cross sections of the {sup 149}Sm(n,p){sup 149}Pm reaction are reported for the first time. The cross sections of the {sup 150}Sm(n,p){sup 150}Pm, {sup 144}Sm(n,p){sup 144}Pm, {sup 152}Sm(n,α){sup 149}Nd and {sup 144}Sm(n,α){sup 141}Nd reactions at different neutron energies reported in the present work can be added as new data in the nuclear databases.

Diffusion Parameters of BeO by the Pulsed Neutron Method; Calcul des Parametres de Diffusion de BeO par la Methode des Neutrons Pulses; Opredelenie diffuzionnykh parametrov BeO s pomoshch'yu metoda impul'snykh nejtronov; Determinacion de los Parametros de Difusion en el BeO por el Metodo de los Neutrones Pulsados

Energy Technology Data Exchange (ETDEWEB)

Joshi, B. V.; Nargundkar, V. R.; Subbarao, K. [Atomic Energy Establishment Trombay, Bombay (India)

1965-08-15

The use of the pulsed neutron method for the precise determination of the diffusion parameters of moderators is described. The diffusion parameters of BeO have been obtained by this method. The neutron bursts were produced from a cascade accelerator by pulsing the ion source and using the Be (d, n) reaction. The detector was an enriched boron trifluoride proportional counter. It is shown that by a proper choice of the counter position arid length, and the source position, most of the space harmonics can be eliminated. Any constant background can be accounted for in the calculation of the decay constant. Very large bucklings were not used to avoid time harmonics. Any remaining harmonic content was rendered ineffective by the use of adequate time delay. The decay constant of the fundamental mode of the thermal neutron population was determined for several bucklings. Conditions to be satisfied for an accurate determination of the diffusion cooling constant C are discussed. The following values are obtained for BeO: {lambda}{sub 0} = absorption constant = 156.02 {+-} 4.37 s{sup -1} D = diffusion coefficient = (1.3334 {+-} 0.0128) x 10{sup 5} cm{sup 2}/s C = diffusion cooling constant = (-4.8758 {+-} 0.5846) x 10{sup 5} cm{sup 4}/s. The effect of neglecting the contribution of the B{sup 6} term on the determination of the diffusion parameters was estimated and is shown to be considerable. The reason for the longstanding discrepancy between the values of C obtained for the same moderator by different workers is attributed to this. (author) [French] Les auteurs decrivent l'emploi de la methode des neutrons puises pour la determination precise des parametres de diffusion des ralentisseurs. Ils ont calculi ceux de la glucine par cette methode. Des deuterons puises au moyen d'un accelerateur a cascade produisaient les bouffees de neutrons par la reaction Be (d, n). Le detecteur etait constitue par un compteur proportionnel au BF{sub 3} enrichi. En choisissant convenablement

Preliminary Formulation of Finite Element Solution for the 1-D, 1-G Time Dependent Neutron Diffusion Equation without Consideration about Delay Neutron

Energy Technology Data Exchange (ETDEWEB)

Ryu, Eun Hyun; Song, Yong Mann; Park, Joo Hwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-05-15

If time-dependent equation is solved with the FEM, the limitation of the input geometry will disappear. It has often been pointed out that the numerical methods implemented in the RFSP code are not state-of-the-art. Although an acceleration method such as the Coarse Mesh Finite Difference (CMFD) for Finite Difference Method (FDM) does not exist for the FEM, one should keep in mind that the number of time steps for the transient simulation is not large. The rigorous formulation in this study will richen the theoretical basis of the FEM and lead to an extension of the dynamics code to deal with a more complicated problem. In this study, the formulation for the 1-D, 1-G Time Dependent Neutron Diffusion Equation (TDNDE) without consideration of the delay neutron will first be done. A problem including one multiplying medium will be solved. Also several conclusions from a comparison between the numerical and analytic solutions, a comparison between solutions with various element orders, and a comparison between solutions with different time differencing will be made to be certain about the formulation and FEM solution. By investigating various cases with different values of albedo, theta, and the order of elements, it can be concluded that the finite element solution is agree well with the analytic solution. The higher the element order used, the higher the accuracy improvements are obtained.

Small-angle neutron polarization for the /sup 2/H(d vector,n vector)/sup 3/He reaction near Esub(d) = 8MeV

Energy Technology Data Exchange (ETDEWEB)

Tornow, W.; Woye, W.; Mack, G. (Tuebingen Univ. (Germany, F.R.). Physikalisches Inst.); Walter, R.L.; Floyd, C.E.; Guss, P.P.; Byrd, R.C. (Duke Univ., Durham, NC (USA). Dept. of Physics; Triangle Universities Nuclear Lab., Durham, NC (USA))

1981-12-15

Considerable improvement in the quality of analyzing power experiments performed with polarized fast neutrons has been achieved during the last few years by using neutrons from the polarization transfer reaction /sup 2/H(d vector,n vector)/sup 3/He at a reaction angle of theta = 0/sup 0/. To compromise in these experiments between intensity problems and finite geometry corrections, it is desirable in some instances to subtend a full-width angle ..delta..theta of 20/sup 0/ (lab) centered about theta = 0/sup 0/. In order to investigate the suitability of this reaction as a source of polarized neutrons for cases where the scatterer is close to the neutron source, the neutron polarization of the reaction /sup 2/H(d vector,n vector)/sup 3/He has been studied with ..delta..theta of about 3/sup 0/ in 3/sup 0/ steps out to theta = 20/sup 0/ (lab). An incident deuteron energy near 8 MeV was chosen to yield outgoing neutrons at 11.0 MeV, a typical energy for neutron analyzing power experiments. It is found that the effective neutron polarization, a combination of the two polarizations measured when the direction of the deuteron polarization is inverted or flipped at the polarized ion source, is large and nearly constant for angles between theta = 0/sup 0/ and theta = 10/sup 0/ (lab).

Coupling of 3D neutronics models with the system code ATHLET

International Nuclear Information System (INIS)

Langenbuch, S.; Velkov, K.

1999-01-01

The system code ATHLET for plant transient and accident analysis has been coupled with 3D neutronics models, like QUABOX/CUBBOX, for the realistic evaluation of some specific safety problems under discussion. The considerations for the coupling approach and its realization are discussed. The specific features of the coupled code system established are explained and experience from first applications is presented. (author)

The analytic nodal diffusion solver ANDES in multigroups for 3D rectangular geometry: Development and performance analysis

International Nuclear Information System (INIS)

Lozano, Juan-Andres; Garcia-Herranz, Nuria; Ahnert, Carol; Aragones, Jose-Maria

2008-01-01

In this work we address the development and implementation of the analytic coarse-mesh finite-difference (ACMFD) method in a nodal neutron diffusion solver called ANDES. The first version of the solver is implemented in any number of neutron energy groups, and in 3D Cartesian geometries; thus it mainly addresses PWR and BWR core simulations. The details about the generalization to multigroups and 3D, as well as the implementation of the method are given. The transverse integration procedure is the scheme chosen to extend the ACMFD formulation to multidimensional problems. The role of the transverse leakage treatment in the accuracy of the nodal solutions is analyzed in detail: the involved assumptions, the limitations of the method in terms of nodal width, the alternative approaches to implement the transverse leakage terms in nodal methods - implicit or explicit -, and the error assessment due to transverse integration. A new approach for solving the control rod 'cusping' problem, based on the direct application of the ACMFD method, is also developed and implemented in ANDES. The solver architecture turns ANDES into an user-friendly, modular and easily linkable tool, as required to be integrated into common software platforms for multi-scale and multi-physics simulations. ANDES can be used either as a stand-alone nodal code or as a solver to accelerate the convergence of whole core pin-by-pin code systems. The verification and performance of the solver are demonstrated using both proof-of-principle test cases and well-referenced international benchmarks

Prompt-gamma neutron activation analysis system design. Effects of D-T versus D-D neutron generator source selection

International Nuclear Information System (INIS)

Shypailo, R.J.; Ellis, K.J.

2008-01-01

Prompt-gamma neutron activation (PGNA) analysis is used for the non-invasive measurement of human body composition. Advancements in portable, compact neutron generator design have made those devices attractive as neutron sources. Two distinct generators are available: D-D with 2.5 MeV and D-T with 14.2 MeV neutrons. To compare the performance of these two units in our present PGNA system, we performed Monte Carlo simulations (MCNP-5; Los Alamos National Laboratory) evaluating the nitrogen reactions produced in tissue-equivalent phantoms and the effects of background interference on the gamma-detectors. Monte Carlo response curves showed increased gamma production per unit dose when using the D-D generator, suggesting that it is the more suitable choice for smaller sized subjects. The increased penetration by higher energy neutrons produced by the D-T generator supports its utility when examining larger, especially obese, subjects. A clinical PGNA analysis design incorporating both neutron generator options may be the best choice for a system required to measure a wide range of subject phenotypes. (author)

3-D tracking in a miniature time projection chamber

Energy Technology Data Exchange (ETDEWEB)

Vahsen, S.E., E-mail: sevahsen@hawaii.edu [University of Hawaii, 2505 Correa Road, Honolulu, HI 96822 (United States); Hedges, M.T.; Jaegle, I.; Ross, S.J.; Seong, I.S.; Thorpe, T.N.; Yamaoka, J. [University of Hawaii, 2505 Correa Road, Honolulu, HI 96822 (United States); Kadyk, J.A.; Garcia-Sciveres, M. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States)

2015-07-11

The three-dimensional (3-D) detection of millimeter-scale ionization trails is of interest for detecting nuclear recoils in directional fast neutron detectors and in direction-sensitive searches for weakly interacting massive particles (WIMPs), which may constitute the Dark Matter of the universe. We report on performance characterization of a miniature gas target Time Projection Chamber (TPC) where the drift charge is avalanche-multiplied with Gas Electron Multipliers (GEMs) and detected with the ATLAS FE-I3 Pixel Application Specific Integrated Circuit (ASIC). We report on measurements of gain, gain resolution, point resolution, diffusion, angular resolution, and energy resolution with low-energy X-rays, cosmic rays, and alpha particles, using the gases Ar:CO{sub 2} (70:30) and He:CO{sub 2} (70:30) at atmospheric pressure. We discuss the implications for future, larger directional neutron and Dark Matter detectors. With an eye to designing and selecting components for these, we generalize our results into analytical expressions for detector performance whenever possible. We conclude by demonstrating the 3-D directional detection of a fast neutron source.

Studies of magnetism with inelastic scattering of cold neutrons; Etudes de magnetisme realisees a l'aide de la diffusion inelastique de neutrons froids

Energy Technology Data Exchange (ETDEWEB)

Jacrot, B [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

Inelastic scattering of cold neutrons can be used to study some aspects of magnetism: spins waves, exchange integrals, vicinity of Curie point. After description of the experimental set-up, several experiments, in the fields mentioned above, are analysed. (author) [French] La technique de diffusion inelastique des neutrons froids est utilisee pour etudier certains aspects du magnetisme: ondes de spins, integrales d'echange, etude au voisinage du point de Curie, etc. Apres une description de l'appareillage, on analyse diverses experiences effectuees dans les domaines enumeres plus haut. (auteur)

The role of IL-4 gene 70 bp VNTR and ACE gene I/D variants in Familial Mediterranean fever.

Science.gov (United States)

Yigit, Serbülent; Tural, Sengul; Tekcan, Akın; Tasliyurt, Turker; Inanir, Ahmet; Uzunkaya, Süheyla; Kismali, Gorkem

2014-05-01

Familial Mediterranean fever (FMF) is characterized by recurrent attacks of fever and inflammation in the peritoneum, synovium, or pleura, accompanied by pain. It is an autosomal recessive disease caused by mutations in the MEFV (MEditerranean FeVer) gene. Patients with similar genotypes exhibit phenotypic diversity. As a result, the variations in different genes could be responsible for the clinical findings of this disease. In previous studies genes encoding Angiotensin-Converting Enzyme (ACE) and IL-4 (Interleukin-4) were found to be associated with rheumatologic and autoimmune diseases. In the present study we hypothesized whether ACE I/D or IL-4 70 bp variable tandem repeats (VNTR) genes are associated with FMF and its clinical findings in Turkish patients. Genomic DNA obtained from 670 persons (339 patients with FMF and 331 healthy controls) was used in the study. Genotypes for an ACE gene I/D polymorphism and IL-4 gene 70 bp VNTR were determined by polymerase chain reaction with specific primers. To our knowledge, this is the first study examining ACE gene I/D polymorphism and IL-4 gene 70 bp VNTR polymorphism in FMF patients. As a result, there was a statistically significant difference between the groups with respect to genotype distribution (pACE gene DD genotype was associated with an increased risk in FMF [pACE genotype frequencies according to the clinical characteristics, we found a statistically significant association between DD+ID genotype and fever (p=0.04). In addition IL-4 gene P1P1 genotype was associated with FMF (pACE gene and P1 allele or P1P1 genotype of IL-4 gene may be important molecular markers for susceptibility of FMF. Copyright © 2014 Elsevier Ltd. All rights reserved.

Solution of two energy-group neutron diffusion equation by triangular elements

International Nuclear Information System (INIS)

Correia Filho, A.

1981-01-01

The application of the triangular finite elements of first order in the solution of two energy-group neutron diffusion equation in steady-state conditions is aimed at. The EFTDN (triangular finite elements in neutrons diffusion) computer code in FORTRAN IV language is developed. The discrete formulation of the diffusion equation is obtained applying the Galerkin method. The power method is used to solve the eigenvalues' problem and the convergence is accelerated through the use of Chebshev polynomials. For the equation systems solution the Gauss method is applied. The results of the analysis of two test-problems are presented. (Author) [pt

Procedure for obtaining neutron diffusion coefficients from neutron transport Monte Carlo calculations (AWBA Development Program)

International Nuclear Information System (INIS)

Gast, R.C.

1981-08-01

A procedure for defining diffusion coefficients from Monte Carlo calculations that results in suitable ones for use in neutron diffusion theory calculations is not readily obtained. This study provides a survey of the methods used to define diffusion coefficients from deterministic calculations and provides a discussion as to why such traditional methods cannot be used in Monte Carlo. This study further provides the empirical procedure used for defining diffusion coefficients from the RCP01 Monte Carlo program

Feasibility of the integration of CRONOS, a 3-D neutronics code, into real-time simulators

International Nuclear Information System (INIS)

Ragusa, J.C.

2001-01-01

In its effort to contribute to nuclear power plant safety, CEA proposes the integration of an engineering grade 3-D neutronics code into a real-time plant analyser. This paper describes the capabilities of the neutronics code CRONOS to achieve a fast running performance. First, we will present current core models in simulators and explain their drawbacks. Secondly, the mean features of CRONOS's spatial-kinetics methods will be reviewed. We will then present an optimum core representation with respect to mesh size, choice of finite elements (FE) basis and execution time, for accurate results as well as the multi 1-D thermal-hydraulics (T/H) model developed to take into account 3-D effects in updating the cross-sections. A Main Steam Line Break (MSLB) End-of-Life (EOL) Hot-Zero-Power (HZP) accident will be used as an example, before we conclude with the perspectives of integrating CRONOS's 3-D core model into real-time simulators. (author)

Feasibility of the integration of CRONOS, a 3-D neutronics code, into real-time simulators

Energy Technology Data Exchange (ETDEWEB)

Ragusa, J.C. [CEA Saclay, Dept. de Mecanique et de Technologie, 91 - Gif-sur-Yvette (France)

2001-07-01

In its effort to contribute to nuclear power plant safety, CEA proposes the integration of an engineering grade 3-D neutronics code into a real-time plant analyser. This paper describes the capabilities of the neutronics code CRONOS to achieve a fast running performance. First, we will present current core models in simulators and explain their drawbacks. Secondly, the mean features of CRONOS's spatial-kinetics methods will be reviewed. We will then present an optimum core representation with respect to mesh size, choice of finite elements (FE) basis and execution time, for accurate results as well as the multi 1-D thermal-hydraulics (T/H) model developed to take into account 3-D effects in updating the cross-sections. A Main Steam Line Break (MSLB) End-of-Life (EOL) Hot-Zero-Power (HZP) accident will be used as an example, before we conclude with the perspectives of integrating CRONOS's 3-D core model into real-time simulators. (author)

Three-group albedo method applied to the diffusion phenomenon with up-scattering of neutrons

International Nuclear Information System (INIS)

Terra, Andre M. Barge Pontes Torres; Silva, Jorge A. Valle da; Cabral, Ronaldo G.

2007-01-01

The main objective of this research is to develop a three-group neutron Albedo algorithm considering the up-scattering of neutrons in order to analyse the diffusion phenomenon in nonmultiplying media. The neutron Albedo method is an analytical method that does not try to solve describing explicit equations for the neutron fluxes. Thus the neutron Albedo methodology is very different from the conventional methodology, as the neutron diffusion theory model. Graphite is analyzed as a model case. One major application is in the determination of the nonleakage probabilities with more understandable results in physical terms than conventional radiation transport method calculations. (author)

Positive Association of D Allele of ACE Gene With High Altitude Pulmonary Edema in Indian Population.

Science.gov (United States)

Bhagi, Shuchi; Srivastava, Swati; Tomar, Arvind; Bala Singh, Shashi; Sarkar, Soma

2015-06-01

High altitude pulmonary edema (HAPE) is a potentially fatal high altitude illness occurring as a result of hypobaric hypoxia with an unknown underlying genetic mechanism. Recent studies have shown a possible association between HAPE and polymorphisms in genes of the renin-angiotensin-aldosterone system (RAAS), which play a key role in sensitivity of an individual toward HAPE. For the present investigation, study groups consisted of HAPE patients (HAPE) and acclimatized control subjects (rCON). Four single-nucleotide polymorphisms (SNPs) were genotyped using restriction fragment length polymorphism (RFLP) analysis in genes of the RAAS pathway, specifically, renin (REN) C(-4063)T (rs41317140) and RENi8-83 (rs2368564), angiotensin (AGT) M(235)T (rs699), and angiotensin-converting enzyme (ACE) insertion/deletion (I/D) (rs1799752). Only the I/D polymorphism of the ACE gene showed a significant difference between the HAPE and rCON groups. The frequency of the D allele was found to be significantly higher in the HAPE group. Arterial oxygen saturation levels were significantly lower in the HAPE group compared with the rCON group and also decreased in the I/D and D/D genotypes compared with the I/I genotype in these groups. The other polymorphisms occurring in the REN and AGT genes were not significantly different between the 2 groups. These findings demonstrate a possible association of the I/D polymorphism of the ACE gene with the development of HAPE, with D/D being the at-risk genotype. Copyright © 2015 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

Determination of thermal neutrons diffusion length in graphite

International Nuclear Information System (INIS)

Garcia Fite, J.

1959-01-01

The diffusion length of thermal neutrons in graphite using the less possible quantity of material has been determined. The proceeding used was the measurement in a graphite pile which has a punctual source of rapid neutrons inside surrounded by a reflector medium (paraffin or water). The measurement was done in the following conditions: a) introducing an aluminium plate between both materials. b) Introducing a cadmium plate between both materials. (Author) 91 refs

Current trends in methods for neutron diffusion calculations

International Nuclear Information System (INIS)

Adams, C.H.

1977-01-01

Current work and trends in the application of neutron diffusion theory to reactor design and analysis are reviewed. Specific topics covered include finite-difference methods, synthesis methods, nodal calculations, finite-elements and perturbation theory

Evaluation of Association of ADRA2A rs553668 and ACE I/D Gene Polymorphisms with Obesity Traits in the Setapak Population, Malaysia.

Science.gov (United States)

Shunmugam, Vicneswari; Say, Yee-How

2016-02-01

α-adrenergic receptor 2A (ADRA2A) and angiotensin-converting enzyme (ACE) genes have been variably associated with obesity and its related phenotypes in different populations worldwide. This cross-sectional study aims to investigate the association of adrenergic receptor α2A (ADRA2A) rs553668 and angiotensin-converting enzyme (ACE) I/D single nucleotide polymorphisms (SNPs) with obesity traits (body mass index-BMI; waist-hip ratio-WHR; total body fat percentage - TBF) in a Malaysian population. Demographic and clinical variables were initially collected from 230 subjects via convenience sampling among residents and workers in Setapak, Malaysia, but in the end only 214 multi-ethnic Malaysians (99 males; 45 Malays, 116 ethnic Chinese, and 53 ethnic Indians) were available for statistical analysis. Genotyping was performed by polymerase chain reaction using DNA extracted from mouthwash samples. The overall minor allele frequencies (MAFs) for ADRA2A rs553668 and ACE I/D were 0.55 and 0.56, respectively. Allele distribution of ACE I/D was significantly associated with ethnicity and WHR class. Logistic regression analysis showed that subjects with the ACE II genotype and I allele were, respectively, 2.15 and 1.55 times more likely to be centrally obese, but when adjusted for age and ethnicity, this association was abolished. Covariate analysis controlling for age, gender, and ethnicity also showed similar results, where subjects carrying the II genotype or I allele did not have significantly higher WHR. Combinatory genotype and allele analysis for ADRA2A rs553668 and ACE I/D showed that subjects with both ADRA2A rs553668 GG and ACE I/D II genotypes had significant lowest WHR compared to other genotype combinations. The ACE II genotype might be a protective factor against central adiposity risk among the Malaysian population when in combination with the ADRA2A rs553668 GG genotype.

Nodal spectrum method for solving neutron diffusion equation

International Nuclear Information System (INIS)

Sanchez, D.; Garcia, C. R.; Barros, R. C. de; Milian, D.E.

1999-01-01

Presented here is a new numerical nodal method for solving static multidimensional neutron diffusion equation in rectangular geometry. Our method is based on a spectral analysis of the nodal diffusion equations. These equations are obtained by integrating the diffusion equation in X, Y directions and then considering flat approximations for the current. These flat approximations are the only approximations that are considered in this method, as a result the numerical solutions are completely free from truncation errors. We show numerical results to illustrate the methods accuracy for coarse mesh calculations

Angiotensin converting enzyme (ACE and ACE2 bind integrins and ACE2 regulates integrin signalling.

Directory of Open Access Journals (Sweden)

Nicola E Clarke

Full Text Available The angiotensin converting enzymes (ACEs are the key catalytic components of the renin-angiotensin system, mediating precise regulation of blood pressure by counterbalancing the effects of each other. Inhibition of ACE has been shown to improve pathology in cardiovascular disease, whilst ACE2 is cardioprotective in the failing heart. However, the mechanisms by which ACE2 mediates its cardioprotective functions have yet to be fully elucidated. Here we demonstrate that both ACE and ACE2 bind integrin subunits, in an RGD-independent manner, and that they can act as cell adhesion substrates. We show that cellular expression of ACE2 enhanced cell adhesion. Furthermore, we present evidence that soluble ACE2 (sACE2 is capable of suppressing integrin signalling mediated by FAK. In addition, sACE2 increases the expression of Akt, thereby lowering the proportion of the signalling molecule phosphorylated Akt. These results suggest that ACE2 plays a role in cell-cell interactions, possibly acting to fine-tune integrin signalling. Hence the expression and cleavage of ACE2 at the plasma membrane may influence cell-extracellular matrix interactions and the signalling that mediates cell survival and proliferation. As such, ectodomain shedding of ACE2 may play a role in the process of pathological cardiac remodelling.

Diffusion theory model for optimization calculations of cold neutron sources

International Nuclear Information System (INIS)

Azmy, Y.Y.

1987-01-01

Cold neutron sources are becoming increasingly important and common experimental facilities made available at many research reactors around the world due to the high utility of cold neutrons in scattering experiments. The authors describe a simple two-group diffusion model of an infinite slab LD 2 cold source. The simplicity of the model permits to obtain an analytical solution from which one can deduce the reason for the optimum thickness based solely on diffusion-type phenomena. Also, a second more sophisticated model is described and the results compared to a deterministic transport calculation. The good (particularly qualitative) agreement between the results suggests that diffusion theory methods can be used in parametric and optimization studies to avoid the generally more expensive transport calculations

3D structure tensor analysis of light microscopy data for validating diffusion MRI.

Science.gov (United States)

Khan, Ahmad Raza; Cornea, Anda; Leigland, Lindsey A; Kohama, Steven G; Jespersen, Sune Nørhøj; Kroenke, Christopher D

2015-05-01

Diffusion magnetic resonance imaging (d-MRI) is a powerful non-invasive and non-destructive technique for characterizing brain tissue on the microscopic scale. However, the lack of validation of d-MRI by independent experimental means poses an obstacle to accurate interpretation of data acquired using this method. Recently, structure tensor analysis has been applied to light microscopy images, and this technique holds promise to be a powerful validation strategy for d-MRI. Advantages of this approach include its similarity to d-MRI in terms of averaging the effects of a large number of cellular structures, and its simplicity, which enables it to be implemented in a high-throughput manner. However, a drawback of previous implementations of this technique arises from it being restricted to 2D. As a result, structure tensor analyses have been limited to tissue sectioned in a direction orthogonal to the direction of interest. Here we describe the analytical framework for extending structure tensor analysis to 3D, and utilize the results to analyze serial image "stacks" acquired with confocal microscopy of rhesus macaque hippocampal tissue. Implementation of 3D structure tensor procedures requires removal of sources of anisotropy introduced in tissue preparation and confocal imaging. This is accomplished with image processing steps to mitigate the effects of anisotropic tissue shrinkage, and the effects of anisotropy in the point spread function (PSF). In order to address the latter confound, we describe procedures for measuring the dependence of PSF anisotropy on distance from the microscope objective within tissue. Prior to microscopy, ex vivo d-MRI measurements performed on the hippocampal tissue revealed three regions of tissue with mutually orthogonal directions of least restricted diffusion that correspond to CA1, alveus and inferior longitudinal fasciculus. We demonstrate the ability of 3D structure tensor analysis to identify structure tensor orientations that

RETRACTED: Association of the ACE I/D gene polymorphism with sepsis susceptibility and sepsis progression.

Science.gov (United States)

Yang, Chun-Hua; Zhou, Tian-Biao

2015-12-01

This article has been included in a multiple retraction: Chun-Hua Yang and Tian-Biao Zhou Association of the ACE I/D gene polymorphism with sepsis susceptibility and sepsis progression Journal of Renin-Angiotensin-Aldosterone System 1470320314568521, first published on February 3, 2015 doi: 10.1177/1470320314568521 This article has been retracted at the request of the Editors and the Publisher. After conducting a thorough investigation, SAGE found that the submitting authors of a number of papers published in the Journal of the Renin-Angiotensin Aldosterone System ( JRAAS) (listed below) had supplied fabricated contact details for their nominated reviewers. The Editors accepted these papers based on the reports supplied by the individuals using these fake reviewer email accounts. After concluding that the peer review process was therefore seriously compromised, SAGE and the journal Editors have decided to retract all affected articles. Online First articles (these articles will not be published in an issue) Wenzhuang Tang, Tian-Biao Zhou, and Zongpei Jiang Association of the angiotensinogen M235T gene polymorphism with risk of diabetes mellitus developing into diabetic nephropathy Journal of Renin-Angiotensin-Aldosterone System 1470320314563426, first published on December 18, 2014 doi: 10.1177/1470320314563426 Tian-Biao Zhou, Hong-Yan Li, Zong-Pei Jiang, Jia-Fan Zhou, Miao-Fang Huang, and Zhi-Yang Zhou Role of renin-angiotensin-aldosterone system inhibitors in radiation nephropathy Journal of Renin-Angiotensin-Aldosterone System 1470320314563424, first published on December 18, 2014 doi: 10.1177/1470320314563424 Weiqiang Zhong, Zongpei Jiang, and Tian-Biao Zhou Association between the ACE I/D gene polymorphism and T2DN susceptibility: The risk of T2DM developing into T2DN in the Asian population Journal of Renin-Angiotensin-Aldosterone System 1470320314566019, first published on January 26, 2015 doi: 10.1177/1470320314566019 Tian-Biao Zhou, Xue-Feng Guo, Zongpei

Coupling of the 3D neutron kinetic core model DYN3D with the CFD software ANSYS-CFX

International Nuclear Information System (INIS)

Grahn, Alexander; Kliem, Sören; Rohde, Ulrich

2015-01-01

Highlights: • Improved thermal hydraulic description of nuclear reactor cores. • Possibility of three-dimensional flow phenomena in the core, such as cross flow, flow reversal, flow around obstacles. • Simulation at higher spatial resolution as compared to system codes. - Abstract: This article presents the implementation of a coupling between the 3D neutron kinetic core model DYN3D and the commercial, general purpose computational fluid dynamics (CFD) software ANSYS-CFX. In the coupling approach, parts of the thermal hydraulic calculation are transferred to CFX for its better ability to simulate the three-dimensional coolant redistribution in the reactor core region. The calculation of the heat transfer from the fuel into the coolant remains with DYN3D, which incorporates well tested and validated heat transfer models for rod-type fuel elements. On the CFX side, the core region is modeled based on the porous body approach. The implementation of the code coupling is verified by comparing test case results with reference solutions of the DYN3D standalone version. Test cases cover mini and full core geometries, control rod movement and partial overcooling transients

Analysis of the neutron generation from a D-Li neutron source

International Nuclear Information System (INIS)

Gomes, I.

1994-02-01

The study of the neutron generation from the D-Li reaction is an important issue to define the optimum combination of the intervening parameters during the design phase of a D-Li neutron source irradiation facility. The major players in defining the neutron yield from the D-Li reaction are the deuteron incident energy and the beam current, provided that the lithium target is thick enough to stop all incident deuterons. The incident deuteron energy also plays a role on the angular distribution of the generated neutrons, on the energy distribution of the generated neutrons, and on the maximum possible energy of the neutrons. The D-Li reaction produces neutrons with energies ranging from eV's to several MeV's. The angular distribution of these neutrons is dependent on the energy of both, incident deuterons and generated neutrons. The deuterons lose energy interacting with the lithium target material in such a way that the energy of the deuterons inside the lithium target varies from the incident deuteron energy to essentially zero. The first part of this study focuses in analyzing the neutron generation rate from the D-Li reaction as a function of the intervening parameters, in defining the source term, in terms of the energy and angular distributions of the generated neutrons, and finally in providing some insights of the impact of varying input parameters on the generation rate and correlated distributions. In the second part an analytical description of the Monte Carlo sampling procedure of the neutron from the D-Li reaction is provided with the aim at further Monte Carlo transport of the D-Li neutrons

Progress and Overview on Neutronics Modelling Development in RTP

International Nuclear Information System (INIS)

Mohamad Hairie Rabir; Muhammad Rawi Mohamed Zin; Julia Abdul Karim

2016-01-01

Reactor calculation and simulation are significantly important to ensure safety and better utilization of a research reactor. The Malaysian PUSPATI TRIGA Reactor (RTP) achieved initial criticality on June 28, 1982. The reactor is designed to effectively implement the various fields of basic nuclear research, manpower training, and production of radioisotopes. Since early 90s, neutronics modelling were used as part of its routine in-core fuel management activities. The are several computer codes have been used in RTP since then, based on 1D neutron diffusion, 2D neutron diffusion and 3D Monte Carlo neutron transport method. This paper describes current progress and overview on neutronics modelling development in RTP. Several important parameters were analysed such as k_e_f_f, reactivity, neutron flux, power distribution, B_e_f_f, and fission product build-up for the latest core configuration. The developed core neutronics model was validated by means of comparison with experimental and measurement data. Along with the RTP core model, the calculation procedure also developed to establish better prediction capability of RTP behaviour. (author)

FENDL-3 benchmark test with neutronics experiments related to fusion in Japan

International Nuclear Information System (INIS)

Konno, Chikara; Ohta, Masayuki; Takakura, Kosuke; Ochiai, Kentaro; Sato, Satoshi

2014-01-01

Highlights: •We have benchmarked FENDL-3.0 with integral experiments with DT neutron sources in Japan. •The FENDL-3.0 is as accurate as FENDL-2.1 and JENDL-4.0 or more. •Some data in FENDL-3.0 may have some problems. -- Abstract: The IAEA supports and promotes the gathering of the best data from evaluated nuclear data libraries for each nucleus involved in fusion reactor applications and compiles these data as FENDL. In 2012, the IAEA released a major update to FENDL, FENDL-3.0, which extends the neutron energy range from 20 MeV to greater than 60 MeV for 180 nuclei. We have benchmarked FENDL-3.0 versus in situ and TOF experiments using the DT neutron source at FNS at the JAEA and TOF experiments using the DT neutron source at OKTAVIAN at Osaka University in Japan. The Monte Carlo code MCNP-5 and the ACE file of FENDL-3.0 supplied from the IAEA were used for the calculations. The results were compared with measured ones and those obtained using the previous version, FENDL-2.1, and the latest version, JENDL-4.0. It is concluded that FENDL-3.0 is as accurate as or more so than FENDL-2.1 and JENDL-4.0, although some data in FENDL-3.0 may be problematic

An experience in the use the Sn method for 1D/2D/3D spallation target neutronics and shielding calculations

International Nuclear Information System (INIS)

Kryuchkov, V.P.; Chang, J.; Young-Sik, Cho; Voloschenko, A.M.; Sumaneev, O.V.

2005-01-01

A discrete ordinate algorithm for coupled charged/neutral particle transport calculations of the pencil beam problems in 3-dimensional r, θ, z and x,y,z geometries is developed. It is based on the use of the second order of accuracy adaptive WDD (AWDD) scheme for approximation both the continuous slowing down and streaming terms of the charged particle transport equation, and a suitable algorithm for treatment of the extended un collided flux from an initially mono directional beam of charged particles with given spatial distribution in the perpendicular section of the beam. The developed algorithm is an extension to the 3D geometry case of a similar approach, previously implemented for plane mono directional beam in 1D transport code ROZ-6 and for pencil beam r,z geometry problems in 2D transport code KASKAD-S. It is implemented in the 3D transport code KATRIN-2.0 and is applied to the high-energy coupled proton-pion-neutron-photon transport calculations. The updated version of multigroup cross section library SADCO-2.4 for nucleon-meson cascade calculations, coupled with standard neutron and gamma-ray cross-section libraries (CONSYST/ABBN-93 and BUGLE96, for example) below 20 MeV, is used. Some numerical examples are given. (authors)

Vibrations et relaxations dans les molécules biologiques. Apports de la diffusion incohérente inélastique de neutrons

Science.gov (United States)

Zanotti, J.-M.

2005-11-01

Le présent document ne se veut pas un article de revue mais plutôt un élément d'initiation à une technique encore marginale en Biologie. Le lecteur est supposé être un non spécialiste de la diffusion de neutrons poursuivant une thématique à connotation biologique ou biophysique mettant en jeu des phénomènes dynamiques. En raison de la forte section de diffusion incohérente de l'atome d'hydrogène et de l'abondance de cet élément dans les protéines, la diffusion incohérente inélastique de neutrons est une technique irremplaçable pour sonder la dynamique interne des macromolécules biologiques. Après un rappel succinct des éléments théoriques de base, nous décrivons le fonctionnement de différents types de spectromètres inélastiques par temps de vol sur source continue ou pulsée et discutons leurs mérites respectifs. Les deux alternatives utilisées pour décrire la dynamique des protéines sont abordées: (i)l'une en termes de physique statistique, issue de la physique des verres, (ii) la seconde est une interprétation mécanistique. Nous montrons dans ce cas, comment mettre à profit les complémentarités de domaines en vecteur de diffusion et de résolution en énergie de différents spectromètres inélastiques de neutrons (temps de vol, backscattering et spin-écho) pour accéder, à l'aide d'un modèle physique simple, à la dynamique des protéines sur une échelle de temps allant d'une fraction de picoseconde à quelques nanosecondes.

Thermal diffuse scattering in time-of-flight neutron diffraction studied on SBN single crystals

International Nuclear Information System (INIS)

Prokert, F.; Savenko, B.N.; Balagurov, A.M.

1994-01-01

At time-of-flight (TOF) diffractometer D N-2, installed at the pulsed reactor IBR-2 in Dubna, Sr x Ba 1-x Nb 2 O 6 mixed single crystals (SBN-x) of different compositions (0.50 < x< 0.75) were investigated between 15 and 773 K. The diffraction patterns were found to be strongly influenced by the thermal diffuse scattering (TDS). The appearance of the TDS from the long wavelength acoustic models of vibration in single crystals is characterized by the ratio of the velocity of sound to the velocity of neutron. Due to the nature of the TOF Laue diffraction technique used on D N-2, the TDS around Bragg peaks has rather a complex profile. An understanding of the TDS close to Bragg peaks is essential in allowing the extraction of the diffuse scattering occurring at the diffuse ferroelectric phase transition in SBN crystals. 11 refs.; 9 figs.; 1 tab. (author)

Smoking has no impact on survival and it is not associated with ACE gene I/D polymorphism in hemodialysis patients.

Science.gov (United States)

Kiss, István; Kiss, Zoltán; Kerkovits, Lóránt; Paksy, András; Ambrus, Csaba

2017-01-01

The relationship between smoking and mortality in patients on hemodialysis is controversial. Earlier studies showed that the insertion/deletion (I/D) polymorphism of the ACE gene might have an effect on mortality. The aim of this study was to test the impact of smoking on survival and whether this association was influenced by ACE gene I/D polymorphism in patients on maintenance hemodialysis. In this prospective, multicenter cohort study we analyzed 709 prevalent patients on maintenance hemodialysis. Patients were allocated into groups based on their smoking habit. Outcome data were collected during the 144-month follow-up period. Outcomes of current smokers and lifelong non-smokers were compared. In order to control for interactions between predictor variables, we also identified 160 matched pairs for further sub-analysis. The vast majority of patients (67%) were non-smokers, followed by current smokers (22.2%) and ex-smokers (9.8%). Smoking had no impact on survival in the matched pair analysis ( p = 0.99). After adjustment for ACE I/D polymorphism and other co-variates, smoking had no effect on survival. Our data suggest that smoking has no impact on survival; neither is it associated with ACE gene I/D polymorphism in hemodialysis patients.

Time-step selection considerations in the analysis of reactor transients with DIF3D-K

International Nuclear Information System (INIS)

Taiwo, T.A.; Khalil, H.S.; Cahalan, J.E.; Morris, E.E.

1993-01-01

The DIF3D-K code solves the three-dimensional, time-dependent multigroup neutron diffusion equations by using a nodal approach for spatial discretization and either the theta method or one of three space-time factorization approaches for temporal integration of the nodal equations. The three space-time factorization options (namely, improved quasistatic, adiabatic and conventional point kinetics) were implemented because of their potential efficiency advantage for the analysis of transients in which the flux shape changes more slowly than its amplitude. Here we describe the implementation of DIF3D-K as the neutronics module within the SAS-HWR accident analysis code. We also describe the neutronics-related time step selection algorithms and their influence on the accuracy and efficiency of the various solution options

Neutron detection and characterization for non-proliferation applications using 3D computer optical memories [Use of 3D optical computer memory for radiation detectors/dosimeters. Final progress report

International Nuclear Information System (INIS)

Phillips, Gary W.

2000-01-01

We have investigated 3-dimensional optical random access memory (3D-ORAM) materials for detection and characterization of charged particles of neutrons by detecting tracks left by the recoil charged particles produced by the neutrons. We have characterized the response of these materials to protons, alpha particles and carbon-12 nuclei as a functions of dose and energy. We have observed individual tracks using scanning electron microscopy and atomic force microscopy. We are investigating the use of neural net analysis to characterize energetic neutron fields from their track structure in these materials

Confocal fluorometer for diffusion tracking in 3D engineered tissue constructs

Science.gov (United States)

Daly, D.; Zilioli, A.; Tan, N.; Buttenschoen, K.; Chikkanna, B.; Reynolds, J.; Marsden, B.; Hughes, C.

2016-03-01

We present results of the development of a non-contacting instrument, called fScan, based on scanning confocal fluorometry for assessing the diffusion of materials through a tissue matrix. There are many areas in healthcare diagnostics and screening where it is now widely accepted that the need for new quantitative monitoring technologies is a major pinch point in patient diagnostics and in vitro testing. With the increasing need to interpret 3D responses this commonly involves the need to track the diffusion of compounds, pharma-active species and cells through a 3D matrix of tissue. Methods are available but to support the advances that are currently only promised, this monitoring needs to be real-time, non-invasive, and economical. At the moment commercial meters tend to be invasive and usually require a sample of the medium to be removed and processed prior to testing. This methodology clearly has a number of significant disadvantages. fScan combines a fiber based optical arrangement with a compact, free space optical front end that has been integrated so that the sample's diffusion can be measured without interference. This architecture is particularly important due to the "wet" nature of the samples. fScan is designed to measure constructs located within standard well plates and a 2-D motion stage locates the required sample with respect to the measurement system. Results are presented that show how the meter has been used to evaluate movements of samples through collagen constructs in situ without disturbing their kinetic characteristics. These kinetics were little understood prior to these measurements.

D/H diffusion in serpentine

Science.gov (United States)

Pilorgé, Hélène; Reynard, Bruno; Remusat, Laurent; Le Floch, Sylvie; Montagnac, Gilles; Cardon, Hervé

2017-08-01

Interactions between aqueous fluids and ultrabasic rocks are essential processes in a broad range of contexts including hydrothermal alteration on the parent body of carbonaceous chondrites, at mid-oceanic ridge, and in subduction zones. Tracking these processes and understanding reaction kinetics require knowledge of the diffusion of water in rocks, and of isotope fractionation in major minerals forming under hydrous conditions, such as serpentines. We present a study of D/H inter-diffusion in antigorite, a common variety of serpentine. Experiments were performed in a belt apparatus at 315 °C, 450 °C and 540 °C and at 3.0 GPa on natural antigorite powders saturated with interstitial D2O. An experiment was performed in a diamond anvil cell at 350 °C and 2.5 GPa on an antigorite single-crystal loaded with pure D2O. D/(D + H) ratios were mapped using Raman spectroscopy for the experiments at 315 °C, 450 °C and 540 °C and by NanoSIMS for the experiment at 350 °C. As antigorite is a phyllosilicate, diffusion coefficients were obtained for crystallographic directions parallel and perpendicular to the silicate layers (perpendicular and parallel to the c∗-axis, respectively). Arrhenius relations for D/H inter-diffusion coefficients were determined to be DD/H (m2/s) = 4.71 × 10-2 × exp(-207(-33/+58) (kJ/mol)/RT) and DD/H (m2/s) = 1.61 × 10-4 × exp(-192(-34/+93) (kJ/mol)/RT) perpendicular and parallel to the c∗-axis, respectively, and DD/H (m2/s) = 7.09 × 10-3 × exp(-202(-33/+70) (kJ/mol)/RT) for the bulk diffusivity. Assuming D/H inter-diffusion coefficients for antigorite are the same for all serpentine species, closure temperature and diffusion durations are applied to hydrothermal alteration in the oceanic lithosphere, and in CI, CM and CR chondrites. Closure temperatures lie below 300 °C for terrestrial hydrothermal alteration and depend on serpentine variety because they have different typical grain sizes. Closure temperatures lie below 160 °C for

Association between RAS Gene Polymorphisms (ACE I/D, AGT M235T and Henoch-Schönlein Purpura in a Turkish Population

Directory of Open Access Journals (Sweden)

Sinem Nalbantoglu

2013-01-01

Full Text Available Henoch-Schönlein purpura (HSP is a small-vessel vasculitis of autoimmune hypersensitivity, and renin-angiotensin system (RAS regulates vascular homeostasis and inflammation with activation of cytokine release. Thus, we aimed to investigate the association between HSP and ACE I/D and AGT M235T polymorphisms. Genotyping was determined by allele specific PCR and PCR-RFLP. We obtained a significant difference in genotype distribution (p = 0.003 and allele frequencies (p 0.05 and allele frequencies (p > 0.05 of the AGT M235T polymorphism. Risk assessment showed significant risk for HSP in the subjects both with the ID + DD genotype (p = 0.019, OR: 2.288, 95% CI: 1.136–4.609 and D allele (OR: D vs. I: 2.0528, 95% CI: 1.3632–3.0912, p = 0.001 while no significant risk was obtained for HSP in the subjects both with the MT + TT genotype (p = 0.312, OR: 1.3905, 95% CI: 0.7326–2.6391 and T allele (OR: T vs. M: 1.065, 95% CI: 0.729–1.557, p = 0.743. Furthermore, when patients were stratified by the presence of certain systemic complications of HSP, no significant association was detected with ACE I/D, and AGT M235T polymorphisms. Our findings suggest that ACE I/D polymorphism is significantly associated with HSP susceptibility.

Development of high-intensity D-D and D-T neutron sources and neutron filters for medical and industrial applications

International Nuclear Information System (INIS)

Verbeke, J.M.

2000-01-01

This thesis consists of three main parts. The first one relates to boron neutron capture therapy. It summarizes the guidelines obtained by numerical simulations for the treatment of shallow and deep-seated brain tumors, as well as the results on the design of beam-shaping assemblies to moderate D-D and D-T neutrons to epithermal energies. The second part is about boron neutron capture synovectomy for the treatment of rheumatoid arthritis. Optimal neutron energy for treatment and beam-shaping assembly designs are summarized in this section. The last part is on the development of the sealed neutron generator, including experimental results on the prototype ion source and the prototype accelerator column

Current Status and Progress of Developing a D-D Neutron Generator

International Nuclear Information System (INIS)

Kim, In-Jung; Jung, Hwa-Dong; Park, Chang-Su; Jung, Nam-Suk; Chung, Kyoung-Jae; Hwang, Yong-Seok; Choi, H. D.

2006-01-01

The research to develop a D-D neutron generator was begun in 2001. A prototype device was built in 2004, and partly modified in 2005. By using the modified prototype D-D neutron generator, neutron generation runs were performed, and the characteristics of D-D neutron generation was investigated. The final goal of maximum neutron yield is 10 8 n/s, while a yield of 6.5x10 7 n/s has been achieved. Here, the results of neutron generation runs performed by using the modified prototype device are summarized, and the feature of a new ion source to be tested in weeks is briefly described

Angular distributions of fast neutrons scattered by Al, Si, P, S and Zn; Distributions angulaires des neutrons rapides diffuses par Al, Si, P, S et Zn; Usloviya raspredeleniya bystrykh nejtronov, rasseyannykh alyuminiem, kremniem, fosforom i tsinkom; Distribuciones angulares de neutrones rapidos dispersados por Al, Si, P, S y Zn

Energy Technology Data Exchange (ETDEWEB)

Tstjkaija, K; Tanaka, S; Maeuyama, M; Tomita, Y [Japan Atomic Energy Research Institute, Tokai-Mtjea (Japan)

1962-03-15

Differential scattering cross-sections of Al, Si, P, S and Zn for fast neutrons have been measured in an energy range of 3.4 to 4.6 MeV by using the time-of-flight method. Angular distributions of the inelastically scattered neutrons are nearly isotropic in all cases. These results are discussed on the basis of the Hauser-Feshbach theory. (author) [French] Les sections efficaces differentielles de diffusion de Al, Si, P, S et Zn pour des neutrons rapides ont ete mesurees dans la gamme d'energies de 3,4 a 4,6 MeV, en employant la methode du temps de vol. Les distributions angulaires des neutrons diffuses inelastiquement sont presque isotropes dans tous les cas. Les auteurs analysent ces resultats en se fondant sur la theorie de Hauser-Feshbach. (author) [Spanish] Los autores han medido por el metodo del tiempo de vuelo las secciones eficaces diferenciales de dispersion del Al, Si, P, S y Zn para neutrones rapidos de energia comprendida entre 3,4 y 4,6 MeV. Las distribuciones angulares de los neutrones dispersados inelasticamente son casi isotropicas en todos los casos. Los autores analizan los resultados obtenidos basandose en la teoria de Hauser-Feshbach . (author) [Russian] Differentsial'no e sechenie rasseyaniya alyuminiya, kremniya, fosfora, sery i tsinka dlya bystrykh nejtronov izmereno v diapazone ehnergii ot 3,4 do 4,6 Megaehlektronvol't ispol'zovanie m metoda vremeni proleta. Uglovye raspredeleniya neuprugo rasseyannykh nejtronov yavlyayutsya pochti vo vsekh sluchayakh izotropnymi. Jeti rezul'taty obsuzhdayutsya na osnove teorii Hauzera-Feshbakha. (author)

Using one hybrid 3D-1D-3D approach for the conceptual design of WCCB blanket for CFETR

Energy Technology Data Exchange (ETDEWEB)

Jiang, Kecheng; Zhang, Xiaokang [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); University of Science and Technology of China, Hefei, Anhui, 230027 (China); Li, Jia [University of Science and Technology of China, Hefei, Anhui, 230027 (China); Ma, Xuebin [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); University of Science and Technology of China, Hefei, Anhui, 230027 (China); Liu, Songlin, E-mail: slliu@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); University of Science and Technology of China, Hefei, Anhui, 230027 (China)

2017-01-15

Highlights: • The Hybrid 3D-1D-3D approach is used for radial building design of WCCB. • Nuclear heat obtained by this method agrees well with 3D neutronics results. • The final results of temperature and TBR satisfy with the requirements. • All the results show that this approach is high efficiency and high reliability. - Abstract: A hybrid 3D-1D-3D approach is proposed for the conceptual design of a blanket. Firstly, the neutron wall loading (NWL) of each blanket module is obtained through a neutronics calculation employing a 3D model, which contains the geometry outline of in-vacuum vessel components and the exact neutron source distribution. Secondly, a 1D cylindrical model with the blanket module containing a detailed radial building is adopted for the neutronics analysis, with the aim of calculating the tritium breeding ratio (TBR) and nuclear heating. Being normalized to the NWL, the nuclear heating is transferred to a 2D model for thermal-hydraulics analysis using the FLUENT code. Through a series analysis of nuclear-thermal iterations that considers the tritium breeding ratio (TBR) and thermal performance as optimization objectives, the optimized radial building of each module surrounding plasma can be obtained. Thirdly, the 3D structural design of each module is established by adding side walls, cover plates, stiffening plates, and other components based on the radial building. The 3D neutronics and thermal-hydraulics using the detailed blanket modules are re-analyzed. This approach has been successfully applied to the design of a water-cooled ceramic breeder blanket for the Chinese Fusion Engineering Test Reactor (CFETR). The radial building of each blanket module surrounding plasma is optimized. The global tritium breeding ratio (TBR) calculated by the 3D neutronics analysis is 1.21, and the temperature of all materials in the 3D blanket structure is below the upper limits. As indicated by the comparison of the 1D and 3D neutronics and thermal

DNS: Diffuse scattering neutron time-of-flight spectrometer

Directory of Open Access Journals (Sweden)

Yixi Su

2015-08-01

Full Text Available DNS is a versatile diffuse scattering instrument with polarisation analysis operated by the Jülich Centre for Neutron Science (JCNS, Forschungszentrum Jülich GmbH, outstation at the Heinz Maier-Leibnitz Zentrum (MLZ. Compact design, a large double-focusing PG monochromator and a highly efficient supermirror-based polarizer provide a polarized neutron flux of about 107 n cm-2 s-1. DNS is used for the studies of highly frustrated spin systems, strongly correlated electrons, emergent functional materials and soft condensed matter.

Parallel computing for homogeneous diffusion and transport equations in neutronics; Calcul parallele pour les equations de diffusion et de transport homogenes en neutronique

Energy Technology Data Exchange (ETDEWEB)

Pinchedez, K

1999-06-01

Parallel computing meets the ever-increasing requirements for neutronic computer code speed and accuracy. In this work, two different approaches have been considered. We first parallelized the sequential algorithm used by the neutronics code CRONOS developed at the French Atomic Energy Commission. The algorithm computes the dominant eigenvalue associated with PN simplified transport equations by a mixed finite element method. Several parallel algorithms have been developed on distributed memory machines. The performances of the parallel algorithms have been studied experimentally by implementation on a T3D Cray and theoretically by complexity models. A comparison of various parallel algorithms has confirmed the chosen implementations. We next applied a domain sub-division technique to the two-group diffusion Eigen problem. In the modal synthesis-based method, the global spectrum is determined from the partial spectra associated with sub-domains. Then the Eigen problem is expanded on a family composed, on the one hand, from eigenfunctions associated with the sub-domains and, on the other hand, from functions corresponding to the contribution from the interface between the sub-domains. For a 2-D homogeneous core, this modal method has been validated and its accuracy has been measured. (author)

ACE phenotyping in Gaucher disease.

Science.gov (United States)

Danilov, Sergei M; Tikhomirova, Victoria E; Metzger, Roman; Naperova, Irina A; Bukina, Tatiana M; Goker-Alpan, Ozlem; Tayebi, Nahid; Gayfullin, Nurshat M; Schwartz, David E; Samokhodskaya, Larisa M; Kost, Olga A; Sidransky, Ellen

2018-04-01

Gaucher disease is characterized by the activation of splenic and hepatic macrophages, accompanied by dramatically increased levels of angiotensin-converting enzyme (ACE). To evaluate the source of the elevated blood ACE, we performed complete ACE phenotyping using blood, spleen and liver samples from patients with Gaucher disease and controls. ACE phenotyping included 1) immunohistochemical staining for ACE; 2) measuring ACE activity with two substrates (HHL and ZPHL); 3) calculating the ratio of the rates of substrate hydrolysis (ZPHL/HHL ratio); 4) assessing the conformational fingerprint of ACE by evaluating the pattern of binding of monoclonal antibodies to 16 different ACE epitopes. We show that in patients with Gaucher disease, the dramatically increased levels of ACE originate from activated splenic and/or hepatic macrophages (Gaucher cells), and that both its conformational fingerprint and kinetic characteristics (ZPHL/HHL ratio) differ from controls and from patients with sarcoid granulomas. Furthermore, normal spleen was found to produce high levels of endogenous ACE inhibitors and a novel, tightly-bound 10-30 kDa ACE effector which is deficient in Gaucher spleen. The conformation of ACE is tissue-specific. In Gaucher disease, ACE produced by activated splenic macrophages differs from that in hepatic macrophages, as well as from macrophages and dendritic cells in sarcoid granulomas. The observed differences are likely due to altered ACE glycosylation or sialylation in these diseased organs. The conformational differences in ACE may serve as a specific biomarker for Gaucher disease. Copyright © 2018 Elsevier Inc. All rights reserved.

Solution of the neutron diffusion equation at two groups of energy by method of triangular finite elements

International Nuclear Information System (INIS)

Correia Filho, A.

1981-04-01

The Neutron Diffusion Equation at two groups of energy is solved with the use of the Finite - Element Method with first order triangular elements. The program EFTDN (Triangular Finite Elements on Neutron Diffusion) was developed using the language FORTRAN IV. The discrete formulation of the Diffusion Equation is obtained with the application of the Galerkin's Method. In order to solve the eigenvalue - problem, the Method of the Power is applied and, with the purpose of the convergence of the results, Chebshev's polynomial expressions are applied. On the solution of the systems of equations Gauss' Method is applied, divided in two different parts: triangularization of the matrix of coeficients and retrosubstitution taking in account the sparsity of the system. Several test - problems are solved, among then two P.W.R. type reactors, the ZION-1 with 1300 MWe and the 2D-IAEA - Benchmark. Comparision of results with standard solutions show the validity of application of the EFM and precision of the results. (Author) [pt

Verification and validation of ACE-format library created from ENDF/B-VII.0

International Nuclear Information System (INIS)

Chen Chaobin; Hu Zehua; Zhang Benai; Chen Yixue; Wu Jun

2009-01-01

ENDF/B-VII.0, released by the USA Cross Section Evaluation Working Group(CSEWG) in December 2006, was developed in five years since the previous release of ENDF/B-VI.8 and was demonstrated to contain much better physical representations of the data and to perform much better than previus ENDF evaluations over a broad range of applications. We generated ACE-format pointwise cross section library from the ENDF/B-VII.0 neutron reaction sublibrary with the processing code NJOY. The paper provides an overview of ENDF/B-VII.0, a summary of the ACE-format files producing process and a detail description of the validation of the ACE-format library. The conclusion is that the ACE-format library produced is correct. (authors)

A 3-D Thermal Analysis of the HANARO Cold Neutron Moderator Cell

International Nuclear Information System (INIS)

Han, Gee Y.; Kim, Heo Nil

2007-01-01

Fundamental studies on a thermal analysis of a cryogenic system such as a cold neutron source (CNS) have increased significantly for a successful CNS design in cold neutron research during recent years. A three-dimensional (3-D) thermal analysis model for the HANARO CNS was developed and used to accurately predict a temperature distribution between the hydrogen inside and the entire inner and outer surfaces of a moderator cell, whose moderator and cell walls are heated differently, under a steady-state operating condition by using the HEATING 7 code. The objective of this study is primarily to predict a temperature distribution through a heat flow in a cold neutron moderator cell heated from a nuclear heating and cooled by a cryogenic coolant. This paper presents satisfactory results of a steady-state temperature distribution in a cryogenic moderator cell. They are used to support the thermal stress analysis of the moderator cell walls and to provide a safe operation for the HANARO CNS facility

Three-dimensional h-adaptivity for the multigroup neutron diffusion equations

KAUST Repository

Wang, Yaqi

2009-04-01

Adaptive mesh refinement (AMR) has been shown to allow solving partial differential equations to significantly higher accuracy at reduced numerical cost. This paper presents a state-of-the-art AMR algorithm applied to the multigroup neutron diffusion equation for reactor applications. In order to follow the physics closely, energy group-dependent meshes are employed. We present a novel algorithm for assembling the terms coupling shape functions from different meshes and show how it can be made efficient by deriving all meshes from a common coarse mesh by hierarchic refinement. Our methods are formulated using conforming finite elements of any order, for any number of energy groups. The spatial error distribution is assessed with a generalization of an error estimator originally derived for the Poisson equation. Our implementation of this algorithm is based on the widely used Open Source adaptive finite element library deal.II and is made available as part of this library\\'s extensively documented tutorial. We illustrate our methods with results for 2-D and 3-D reactor simulations using 2 and 7 energy groups, and using conforming finite elements of polynomial degree up to 6. © 2008 Elsevier Ltd. All rights reserved.

Diffusion in Coulomb crystals.

Science.gov (United States)

Hughto, J; Schneider, A S; Horowitz, C J; Berry, D K

2011-07-01

Diffusion in Coulomb crystals can be important for the structure of neutron star crusts. We determine diffusion constants D from molecular dynamics simulations. We find that D for Coulomb crystals with relatively soft-core 1/r interactions may be larger than D for Lennard-Jones or other solids with harder-core interactions. Diffusion, for simulations of nearly perfect body-centered-cubic lattices, involves the exchange of ions in ringlike configurations. Here ions "hop" in unison without the formation of long lived vacancies. Diffusion, for imperfect crystals, involves the motion of defects. Finally, we find that diffusion, for an amorphous system rapidly quenched from Coulomb parameter Γ=175 to Coulomb parameters up to Γ=1750, is fast enough that the system starts to crystalize during long simulation runs. These results strongly suggest that Coulomb solids in cold white dwarf stars, and the crust of neutron stars, will be crystalline and not amorphous.

Reduction in 14 MeV neutron generation rate by ICRF injection in D-3He burning plasmas

International Nuclear Information System (INIS)

Matsuura, Hideaki; Nakao, Yasuyuki

2004-01-01

The triton distribution function during ion cyclotron range of frequency (ICRF) waves injection in D- 3 He plasmas is examined by solving the 2-dimensional Fokker-Planck equation. Triton distribution function originally has a non-Maxwellian (tail) component around 1.01 MeV birth energy range due to D(d,p)T fusion reaction. Owing to the extension of the original tail by ICRF injection, the high-energy resonance tritons further increase, and the velocity-averaged T(d,n) 4 He fusion reaction rate coefficient, i.e. 14 MeV neutron generation rate, decreases from the values when triton is assumed to be Maxwellian. It is shown that when tritons absorb ∼1/200 of the fusion power from the waves in typical D- 3 He plasma, i.e. T=80 keV, n D =2x10 20 m -3 , τ E0 =3 sec and B=6T, the 14 MeV neutron generation rate is reduced by about ∼20% from the values for Maxwellian plasmas. (author)

ACE (I/D polymorphism and response to treatment in coronary artery disease: a comprehensive database and meta-analysis involving study quality evaluation

Directory of Open Access Journals (Sweden)

Kitsios Georgios

2009-06-01

Full Text Available Abstract Background The role of angiotensin-converting enzyme (ACE gene insertion/deletion (I/D polymorphism in modifying the response to treatment modalities in coronary artery disease is controversial. Methods PubMed was searched and a database of 58 studies with detailed information regarding ACE I/D polymorphism and response to treatment in coronary artery disease was created. Eligible studies were synthesized using meta-analysis methods, including cumulative meta-analysis. Heterogeneity and study quality issues were explored. Results Forty studies involved invasive treatments (coronary angioplasty or coronary artery by-pass grafting and 18 used conservative treatment options (including anti-hypertensive drugs, lipid lowering therapy and cardiac rehabilitation procedures. Clinical outcomes were investigated by 11 studies, while 47 studies focused on surrogate endpoints. The most studied outcome was the restenosis following coronary angioplasty (34 studies. Heterogeneity among studies (p ACE I/D polymorphism on the response to treatment for the rest outcomes (coronary events, endothelial dysfunction, left ventricular remodeling, progression/regression of atherosclerosis, individual studies showed significance; however, results were discrepant and inconsistent. Conclusion In view of available evidence, genetic testing of ACE I/D polymorphism prior to clinical decision making is not currently justified. The relation between ACE genetic variation and response to treatment in CAD remains an unresolved issue. The results of long-term and properly designed prospective studies hold the promise for pharmacogenetically tailored therapy in CAD.

Physics study of D-D/D-T neutron driven experimental subcritical assembly

International Nuclear Information System (INIS)

Sinha, Amar

2015-01-01

An experimental program to design and study external source driven subcritical assembly has been initiated at BARC. This program is aimed at understanding neutronic characteristics of accelerator driven system at low power level. In this series, a zero-power, sub-critical assembly driven by a D-D/D-T neutron generator has been developed. This system is modular in design and it is first in the series of subcritical assemblies being designed. The subcritical core consists of natural uranium fuel with high density polyethylene as moderator and beryllium oxide as reflector. The subcritical core is coupled to Purnima Neutron Generator. Preliminary experiments have been carried out for spatial flux measurement and reactivity estimation using pulsed neutron source (PNS) techniques. Further experiments are being planned to measure the reactivity and other kinetic parameters using noise methods. This facility would also be used for carrying out studies on effect of source importance and measurement of source multiplication factor k s and external neutron source efficiency φ* in great details. Some experiments with D-D and D-T neutrons have been presented. (author)

Association of ACTN3 R577X but not ACE I/D gene variants with elite rugby union player status and playing position.

Science.gov (United States)

Heffernan, S M; Kilduff, L P; Erskine, R M; Day, S H; McPhee, J S; McMahon, G E; Stebbings, G K; Neale, J P H; Lockey, S J; Ribbans, W J; Cook, C J; Vance, B; Raleigh, S M; Roberts, C; Bennett, M A; Wang, G; Collins, M; Pitsiladis, Y P; Williams, A G

2016-03-01

We aimed to quantify the ACE I/D and ACTN3 R577X (rs1815739) genetic variants in elite rugby athletes (rugby union and league) and compare genotype frequencies to controls and between playing positions. The rugby athlete cohort consisted of 507 Caucasian men, including 431 rugby union athletes that for some analyses were divided into backs and forwards and into specific positional groups: front five, back row, half backs, centers, and back three. Controls were 710 Caucasian men and women. Real-time PCR of genomic DNA was used to determine genotypes using TaqMan probes and groups were compared using χ(2) and odds ratio (OR) statistics. Correction of P values for multiple comparisons was according to Benjamini-Hochberg. There was no difference in ACE I/D genotype between groups. ACTN3 XX genotype tended to be underrepresented in rugby union backs (15.7%) compared with forwards (24.8%, P = 0.06). Interestingly, the 69 back three players (wings and full backs) in rugby union included only six XX genotype individuals (8.7%), with the R allele more common in the back three (68.8%) than controls (58.0%; χ(2) = 6.672, P = 0.04; OR = 1.60) and forwards (47.5%; χ(2) = 11.768, P = 0.01; OR = 2.00). Association of ACTN3 R577X with playing position in elite rugby union athletes suggests inherited fatigue resistance is more prevalent in forwards, while inherited sprint ability is more prevalent in backs, especially wings and full backs. These results also demonstrate the advantage of focusing genetic studies on a large cohort within a single sport, especially when intrasport positional differences exist, instead of combining several sports with varied demands and athlete characteristics. Copyright © 2016 the American Physiological Society.

Coupling of the computational fluid dynamics code ANSYS CFX with the 3D neutron kinetic core model DYN3D

International Nuclear Information System (INIS)

Kliem, S.; Grahn, A.; Rohde, U.; Schuetze, J.; Frank, Th.

2010-01-01

The computational fluid dynamics code ANSYS CFX has been coupled with the neutron-kinetic core model DYN3D. ANSYS CFX calculates the fluid dynamics and related transport phenomena in the reactors coolant and provides the corresponding data to DYN3D. In the fluid flow simulation of the coolant, the core itself is modeled within the porous body approach. DYN3D calculates the neutron kinetics and the fuel behavior including the heat transfer to the coolant. The physical data interface between the codes is the volumetric heat release rate into the coolant. In the prototype that is currently available, the coupling is restricted to single-phase flow problems. In the time domain an explicit coupling of the codes has been implemented so far. Steady-state and transient verification calculations for two small-size test problems confirm the correctness of the implementation of the prototype coupling. The first test problem was a mini-core consisting of nine real-size fuel assemblies with quadratic cross section. Comparison was performed with the DYN3D stand-alone code. In the steady state, the effective multiplication factor obtained by the DYN3D/ANSYS CFX codes hows a deviation of 9.8 pcm from the DYN3D stand-alone solution. This difference can be attributed to the use of different water property packages in the two codes. The transient test case simulated the withdrawal of the control rod from the central fuel assembly at hot zero power in the same mini-core. Power increase during the introduction of positive reactivity and power reduction due to fuel temperature increase are calculated in the same manner by the coupled and the stand-alone codes. The maximum values reached during the power rise differ by about 1 MW at a power level of 50 MW. Beside the different water property packages, these differences are caused by the use of different flow solvers. The same calculations were carried for a mini-core with seven real-size fuel assemblies with hexagonal cross section in

Cascade defect production and irradiation enhanced diffusion in Cu3Au

International Nuclear Information System (INIS)

Kirk, M.A.; Funk, L.L.

1986-03-01

By using the ordering alloy Cu 3 Au and measuring resistivity changes during and following fast-neutron irradiations at IPNS, we have studied cascade defect production and irradiation enhanced diffusion between 10 and 460 0 K. Ordering and disordering rates were measured as functions of irradiation temperature, neutron dose, neutron dose rate, time following cessation of flux, and step annealing. Free and clustered vacancy production was observed. The temperature dependence of the production of total migrating vacancy concentrations was determined. Vacancy sink production was linear with neutron dose and is compared with recent transmission electron microscopy experiments on the production of dislocation loops in this alloy. Time dependent and quasi-steady state vacancy concentrations were measured and compared with solutions of reaction rate equations for irradiation enhanced diffusion. The influence of recombination of vacancies with interstitials is observed at low sink concentrations (low neutron doses)

Thermal diffuse scattering in angular-dispersive neutron diffraction

International Nuclear Information System (INIS)

Popa, N.C.; Willis, B.T.M.

1998-01-01

The theoretical treatment of one-phonon thermal diffuse scattering (TDS) in single-crystal neutron diffraction at fixed incident wavelength is reanalysed in the light of the analysis given by Popa and Willis [Acta Cryst. (1994), (1997)] for the time-of-flight method. Isotropic propagation of sound with different velocities for the longitudinal and transverse modes is assumed. As in time-of-flight diffraction, there exists, for certain scanning variables, a forbidden range in the one-phonon TDS of slower-than-sound neutrons, and this permits the determination of the sound velocity in the crystal. A fast algorithm is given for the TDS correction of neutron diffraction data collected at a fixed wavelength: this algorithm is similar to that reported earlier for the time-of-flight case. (orig.)

Diffuse neutron scattering study of Cu2−xSe

DEFF Research Database (Denmark)

Cava, R. J.; Andersen, Niels Hessel; Clausen, Kurt Nørgaard

1986-01-01

We have measured the diffuse neutron scattering in the hkk plane for Cu2Se and Cu1.8Se at 180°C and 51°C, respectively, in the cubic antifluorite type phase. The diffuse scattering shows significant structure, indicative of correlated short range mobile ion ordering. The short range order is foun...

The 3D tomographic image reconstruction software for prompt-gamma measurement of the boron neutron capture therapy

International Nuclear Information System (INIS)

Morozov, Boris; Auterinen, Iiro; Kotiluoto, Petri; Kortesniemi, Mika

2006-01-01

A tomographic imaging system based on the spatial distribution measurement of the neutron capture reaction during Boron Neutron Capture Therapy (BNCT) would be very useful for clinical purpose. Using gamma-detectors in a 2D-panel, boron neutron capture and hydrogen neutron capture gamma-rays emitted by the neutron irradiated region can be detected, and an image of the neutron capture events can be reconstructed. A 3D reconstruction software package has been written to support the development of a 3D prompt-gamma tomographic system. The package consists of three independent modules: phantom generation, reconstruction and evaluation modules. The reconstruction modules are based on algebraic approach of the iterative reconstruction algorithm (ART), and on the maximum likelihood estimation method (ML-EM). In addition to that, two subsets of the ART, the simultaneous iterative reconstruction technique (SIRT) and the component averaging algorithms (CAV) have been included to the package employing parallel codes for multiprocessor architecture. All implemented algorithms use two different field functions for the reconstruction of the region. One is traditional voxel function, another is, so called, blob function, smooth spherically symmetric generalized Kaiser-Bessel function. The generation module provides the phantom and projections with background by tracing the prompt gamma-rays for a given scanner geometry. The evaluation module makes statistical comparisons between the generated and reconstructed images, and provides figure-of-merit (FOM) values for the applied reconstruction algorithms. The package has been written in C language and tested under Linux and Windows platforms. The simple graphical user interface (GUI) is used for command execution and visualization purposed. (author)

Standard Test Method for Measuring Neutron Fluence and Average Energy from 3H(d,n)4He Neutron Generators by Radioactivation Techniques 1

CERN Document Server

American Society for Testing and Materials. Philadelphia

2009-01-01

1.1 This test method covers a general procedure for the measurement of the fast-neutron fluence rate produced by neutron generators utilizing the 3H(d,n)4He reaction. Neutrons so produced are usually referred to as 14-MeV neutrons, but range in energy depending on a number of factors. This test method does not adequately cover fusion sources where the velocity of the plasma may be an important consideration. 1.2 This test method uses threshold activation reactions to determine the average energy of the neutrons and the neutron fluence at that energy. At least three activities, chosen from an appropriate set of dosimetry reactions, are required to characterize the average energy and fluence. The required activities are typically measured by gamma ray spectroscopy. 1.3 The measurement of reaction products in their metastable states is not covered. If the metastable state decays to the ground state, the ground state reaction may be used. 1.4 The values stated in SI units are to be regarded as standard. No oth...

Diffuse neutron scattering from anion-excess strontium chloride

DEFF Research Database (Denmark)

Goff, J.P.; Clausen, K.N.; Fåk, B.

1992-01-01

The defect structure and diffusional processes have been studied in the anion-excess fluorite (Sr, Y)Cl2.03 by diffuse neutron scattering techniques. Static cuboctahedral clusters found at ambient temperature break up at temperatures below 1050 K, where the anion disorder is highly dynamic. The a...

A Detector for 2-D Neutron Imaging for the Spallation Neutron Source

International Nuclear Information System (INIS)

Britton, Charles L. Jr.; Bryan, W.L.; Wintenberg, Alan Lee; Clonts, Lloyd G.; Warmack, Robert J. Bruce; McKnight, Timothy E.; Frank, Steven Shane; Cooper, Ronald G.; Dudney, Nancy J.; Veith, Gabriel M.

2006-01-01

We have designed, built, and tested a 2-D pixellated thermal neutron detector. The detector is modeled after the MicroMegas-type structure previously published for collider-type experiments. The detector consists of a 4X4 square array of 1 cm 2 pixels each of which is connected to an individual preamplifier-shaper-data acquisition system. The neutron converter is a 10B film on an aluminum substrate. We describe the construction of the detector and the test results utilizing 252Cf sources in Lucite to thermalize the neutrons. Drift electrode (Aluminum) Converter (10B) 3 mm Conversion gap neutron (-900 V)

D-T neutron skyshine experiments at JAERI/FNS

Energy Technology Data Exchange (ETDEWEB)

Nishitani, Takeo; Ochiai, Kentaro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Yoshida, Shigeo [Tokai Univ., Hiratsuka, Kanagawa (JP)] (and others)

2003-03-01

The D-T neutron skyshine experiments have been carried out at the Fusion Neutronics Source (FNS) of JAERI with the neutron yield of {approx}1.7x10{sup 11} n/s. The concrete thickness of the roof and the wall of a FNS target room are 1.15 and 2 m, respectively. The FNS skyshine port with a size of 0.9x0.9 m{sup 2} was open during the experimental period. The radiation dose rate outside the target room was measured as far as about 550 m away from the D-T target point with a spherical rem-counter. The highest neutron dose was about 0.5 {mu}Sv/hr at a distance of 30 m from the D-T target point and the dose rate was attenuated to 0.002 {mu}Sv/hr at a distance of 550 m. The measured neutron dose distribution was analyzed with Monte Carlo code MCNP-4B and a simple line source model. The MCNP calculation overestimates the neutron dose in the distance range larger than 250 m. The neutron spectra were evaluated with a {sup 3}He detector with different thickness of polyethylene neutron moderators. Secondary gamma-rays were measured with high purity Ge detectors and NaI scintillation detectors. (author)

A spectrophotometer-based diffusivity assay reveals that diffusion hindrance of small molecules in extracellular matrix gels used in 3D cultures is dominated by viscous effects.

Science.gov (United States)

Galgoczy, Roland; Pastor, Isabel; Colom, Adai; Giménez, Alicia; Mas, Francesc; Alcaraz, Jordi

2014-08-01

The design of 3D culture studies remains challenging due to the limited understanding of extracellular matrix (ECM)-dependent hindered diffusion and the lack of simple diffusivity assays. To address these limitations, we set up a cost-effective diffusivity assay based on a Transwell plate and the spectrophotometer of a Microplate Reader, which are readily accessible to cell biology groups. The spectrophotometer-based assay was used to assess the apparent diffusivity D of FITC-dextrans with molecular weight (4-70kDa) spanning the physiological range of signaling factors in a panel of acellular ECM gels including Matrigel, fibrin and type I collagen. Despite their technical differences, D data exhibited ∼15% relative difference with respect to FRAP measurements. Our results revealed that diffusion hindrance of small particles is controlled by the enhanced viscosity of the ECM gel in conformance with the Stokes-Einstein equation rather than by geometrical factors. Moreover, we provided a strong rationale that the enhanced ECM viscosity is largely contributed to by unassembled ECM macromolecules. We also reported that gels with the lowest D exhibited diffusion hindrance closest to the large physiologic hindrance of brain tissue, which has a typical pore size much smaller than ECM gels. Conversely, sparse gels (≤1mg/ml), which are extensively used in 3D cultures, failed to reproduce the hindered diffusion of tissues, thereby supporting that dense (but not sparse) ECM gels are suitable tissue surrogates in terms of macromolecular transport. Finally, the consequences of reduced diffusivity in terms of optimizing the design of 3D culture experiments were addressed in detail. Copyright © 2014 Elsevier B.V. All rights reserved.

Simulation software of 3-D two-neutron energy groups for ship reactor with hexagonal fuel subassembly

International Nuclear Information System (INIS)

Zhang Fan; Cai Zhangsheng; Yu Lei; Gui Xuewen

2005-01-01

Core simulation software for 3-D two-neutron energy groups is developed. This software is used to simulate the ship reactor with hexagonal fuel subassembly after 10, 150 and 200 burnup days, considering the hydraulic and thermal feedback. It accurately simulates the characteristics of the fast and thermal neutrons and the detailed power distribution in a reactor under normal and abnormal operation condition. (authors)

Measurement of diffusion length of thermal neutrons in concrete

International Nuclear Information System (INIS)

Moser, M.

2007-04-01

The diffusion length of neutrons with a medium energy < 0.025 eV in concrete were determined using 4π-β detector and gamma detectors. Then it was possible to determine how deep can neutrons penetrate diverse concrete construction parts in a reactor in operation, with this method the dismantling process of a reactor can be planned in terms of what parts can be removed without danger and what parts can be assumed still are activated. (nevyjel)

Modification of Prototype D-D Neutron Generator

International Nuclear Information System (INIS)

Kim, In Jung; Kim, Suk Kwon; Park, Chang Su; Jung, Nam Suk; Jung, Hwa Dong; Park, Ji Young; Hwang, Yong Seok; Choi, H. D.

2005-01-01

The prototype D-D neutron generator was modified in order to enhance the neutron yield. The distance from ion source to target was reduced to increase the ion beam current at target position. Thick Ti target was replaced by thin Ti target which was vacuum-deposited on Cu substrate in order to enhance the target cooling. Performance of the modified device was tested

Use of the helium-3 proportional counter for neutron spectrometry; Utilisation du compteur proportionnel a helium 3 pour la spectrometrie des neutrons

Energy Technology Data Exchange (ETDEWEB)

Vialettes, H; Le Thanh, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-07-01

Up to now, two methods have been mainly used for neutron spectrometry near nuclear installations: - photographic emulsion spectrometry - the so-called, 'multisphere' technique spectrometry. The first method, which is fairly difficult to apply, has a threshold energy of about 500 keV; this is a big disadvantage for an apparatus which has to be used for spectrometry around nuclear installations where the neutron radiation is very much degraded energetically. The second method does not suffer from this disadvantage but the results which it yields are only approximate. In order to extend the energy range of the neutron spectra studied with sufficient accuracy the use of a helium-3 proportional counter has been considered. This report presents the principles of operation of the helium-3 spectrometer, and the calculation methods which make it possible to take into account the two main effects tending to deform the spectra obtained: - energy absorption by the walls of the counter, - energy loss of the incident neutrons due to elastic collisions with helium-3 nuclei. As an example of the application, the shape of the neutron spectrum emitted by a polonium-lithium source is given; the results obtained are in excellent agreement with theoretical predictions. (authors) [French] Jusqu'ici deux methodes ont ete utilisees principalement pour la spectrometrie des neutrons autour des installations nucleaires: - la spectrometrie par emulsions photographiques - la spectrometrie par la technique dite des multispheres. La premiere methode, d'un emploi assez delicat presente un seuil en energie d'environ 500 keV qui est un obstacle serieux a la spectrometrie autour des installations nucleaires ou le rayonnement neutronique est tres degrade en energie. La deuxieme methode ne presente pas cet inconvenient mais les resultats qu'elle permet d'obtenir ne sont qu'approches. Pour etendre la gamme d'energie des spectres de neutrons etudies avec une precision suffisante, l'utilisation du

Impact of I/D polymorphism of ACE gene on risk of development and course of chronic obstructive pulmonary disease.

Science.gov (United States)

Mlak, Radosław; Homa-Mlak, Iwona; Powrózek, Tomasz; Mackiewicz, Barbara; Michnar, Marek; Krawczyk, Paweł; Dziedzic, Marcin; Rubinsztajn, Renata; Chazan, Ryszarda; Milanowski, Janusz; Małecka-Massalska, Teresa

2016-04-01

Chronic obstructive pulmonary disease (COPD) affects more than 10% of the world's population over 40 years of age. The main exogenous risk factor is cigarette smoking; however, only 20% of smokers develop COPD, indicating that some other factors, e.g. genetic, may play an important role in the disease pathogenesis. Recent research indicates that ACE (angiotensin-converting enzyme) may be a susceptibility gene for asthma or COPD. The aim of our study was to determine the influence of I/D (insertion/deletion) polymorphism of the ACE gene (AluYa5, rs4646994) on the risk and course of COPD. We investigated ACE I/D polymorphism in 206 COPD and 165 healthy Caucasian subjects. In the generalized linear model (GLZ) analysis of the influence of selected factors on presence of COPD we found a significant independent effect for male sex (repeatedly increases the risk of COPD, OR = 7.7, p = 0.049), as well as smoking or lower body mass index, but only in combination with older age (OR = 0.96, p = 0.003 and OR = 1.005, p = 0.04 respectively). Interestingly, analysis of factors which may influence the risk of a higher number of exacerbations demonstrated that occurrence of DD genotype, but only in men, is associated with a lower risk (OR = 0.7, p = 0.03) of this complication. We suggest that ACE may not be a susceptibility gene for the origin of COPD but a disease-modifying gene. Since the impact of I/D polymorphism of the ACE gene on COPD risk is moderate or negligible, other molecular changes, that will help predict the development of this disease, should still be sought.

Fourier convergence analysis applied to neutron diffusion Eigenvalue problem

International Nuclear Information System (INIS)

Lee, Hyun Chul; Noh, Jae Man; Joo, Hyung Kook

2004-01-01

Fourier error analysis has been a standard technique for the stability and convergence analysis of linear and nonlinear iterative methods. Though the methods can be applied to Eigenvalue problems too, all the Fourier convergence analyses have been performed only for fixed source problems and a Fourier convergence analysis for Eigenvalue problem has never been reported. Lee et al proposed new 2-D/1-D coupling methods and they showed that the new ones are unconditionally stable while one of the two existing ones is unstable at a small mesh size and that the new ones are better than the existing ones in terms of the convergence rate. In this paper the convergence of method A in reference 4 for the diffusion Eigenvalue problem was analyzed by the Fourier analysis. The Fourier convergence analysis presented in this paper is the first one applied to a neutronics eigenvalue problem to the best of our knowledge

Development of an Analytic Nodal Diffusion Solver in Multi-groups for 3D Reactor Cores with Rectangular or Hexagonal Assemblies

Energy Technology Data Exchange (ETDEWEB)

Lozano, Juan Andres; Aragones, Jose Maria; Garcia-Herranz, Nuria [Universidad Politecnica de Madrid, 28006 Jose Gutierrez Abascal 2, Madrid (Spain)

2008-07-01

More accurate modelling of physical phenomena involved in present and future nuclear reactors requires a multi-scale and multi-physics approach. This challenge can be accomplished by the coupling of best-estimate core-physics, thermal-hydraulics and multi-physics solvers. In order to make viable that coupling, the current trends in reactor simulations are along the development of a new generation of tools based on user-friendly, modular, easily linkable, faster and more accurate codes to be integrated in common platforms. These premises are in the origin of the NURESIM Integrated Project within the 6. European Framework Program, which is envisaged to provide the initial step towards a Common European Standard Software Platform for nuclear reactors simulations. In the frame of this project and to reach the above-mentioned goals, a 3-D multigroup nodal solver for neutron diffusion calculations called ANDES (Analytic Nodal Diffusion Equation Solver) has been developed and tested in-depth in this Thesis. ANDES solves the steady-state and time-dependent neutron diffusion equation in three-dimensions and any number of energy groups, utilizing the Analytic Coarse-Mesh Finite-Difference (ACMFD) scheme to yield the nodal coupling equations. It can be applied to both Cartesian and triangular-Z geometries, so that simulations of LWR as well as VVER, HTR and fast reactors can be performed. The solver has been implemented in a fully encapsulated way, enabling it as a module to be readily integrated in other codes and platforms. In fact, it can be used either as a stand-alone nodal code or as a solver to accelerate the convergence of whole core pin-by-pin code systems. Verification of performance has shown that ANDES is a code with high order definition for whole core realistic nodal simulations. In this paper, the methodology developed and involved in ANDES is presented. (authors)

Study by neutron diffusion of local order liquid sulfur around the polymerization transition

International Nuclear Information System (INIS)

Descotes, L.

1994-05-01

We studied the liquid sulfur according to the temperature. The sulfur is one of the most complicated elementary liquid. We experimented the neutron diffusion by the powder orthorhombic sulfur. The complexity at the polymerization transition are only accompanied by weak local structural transfer. 231 refs., 48 figs., 8 tabs., 3 annexes

The use of diffusion theory to compute invasion effects for the pulsed neutron thermal decay time log

International Nuclear Information System (INIS)

Tittle, C.W.

1992-01-01

Diffusion theory has been successfully used to model the effect of fluid invasion into the formation for neutron porosity logs and for the gamma-gamma density log. The purpose of this paper is to present results of computations using a five-group time-dependent diffusion code on invasion effects for the pulsed neutron thermal decay time log. Previous invasion studies by the author involved the use of a three-dimensional three-group steady-state diffusion theory to model the dual-detector thermal neutron porosity log and the gamma-gamma density log. The five-group time-dependent code MGNDE (Multi-Group Neutron Diffusion Equation) used in this work was written by Ferguson. It has been successfully used to compute the intrinsic formation life-time correction for pulsed neutron thermal decay time logs. This application involves the effect of fluid invasion into the formation

Assessment of the rs4340 ACE gene polymorphism in acute coronary syndrome in a Western Mexican population.

Science.gov (United States)

Valdez-Haro, A; Valle, Y; Valdes-Alvarado, E; Casillas-Muñoz, F; Muñoz-Valle, J F; Reynoso-Villalpando, G L; Flores-Salinas, H E; Padilla-Gutiérrez, J R

2017-09-27

Acute coronary syndrome (ACS) is considered one of the main causes of death worldwide. Contradictory findings concerning the impact of the angiotensin-converting enzyme (ACE) gene on cardiovascular diseases have been reported. Previous conclusions point out that the variability in results depends on ethnicity and genetic polymorphisms to determine the association of rs4340 polymorphisms of the ACE gene and ACE circulating levels in ACS. Genotyping of rs4340 polymorphisms was performed in a total of 600 individuals from Western Mexico divided into two groups: the ACS and the control group (CG). The polymorphisms were identified by polymerase chain reaction. Serum ACE concentration was determined by enzyme-linked immunosorbent assay. D/D carriers had higher ACE levels than I/I carriers (3.6 vs 2.8 ng/mL, P ACE concentration levels; however, the polymorphism was not associated with ACS.

Study by neutron diffusion of local order liquid sulfur around the polymerization transition; Etude par diffusion de neutrons de l`ordre local du soufre liquide autour de la transition de polymerisation

Energy Technology Data Exchange (ETDEWEB)

Descotes, L

1994-05-01

We studied the liquid sulfur according to the temperature. The sulfur is one of the most complicated elementary liquid. We experimented the neutron diffusion by the powder orthorhombic sulfur. The complexity at the polymerization transition are only accompanied by weak local structural transfer. 231 refs., 48 figs., 8 tabs., 3 annexes.

Thermal neutron diffusion parameters dependent on the flux energy distribution in finite hydrogenous media

International Nuclear Information System (INIS)

Drozdowicz, K.

1999-01-01

Macroscopic parameters for a description of the thermal neutron transport in finite volumes are considered. A very good correspondence between the theoretical and experimental parameters of hydrogenous media is attained. Thermal neutrons in the medium possess an energy distribution, which is dependent on the size (characterized by the geometric buckling) and on the neutron transport properties of the medium. In a hydrogenous material the thermal neutron transport is dominated by the scattering cross section which is strongly dependent on energy. A monoenergetic treatment of the thermal neutron group (admissible for other materials) leads in this case to a discrepancy between theoretical and experimental results. In the present paper the theoretical definitions of the pulsed thermal neutron parameters (the absorption rate, the diffusion coefficient, and the diffusion cooling coefficient) are based on Nelkin's analysis of the decay of a neutron pulse. Problems of the experimental determination of these parameters for a hydrogenous medium are discussed. A theoretical calculation of the pulsed parameters requires knowledge of the scattering kernel. For thermal neutrons it is individual for each hydrogenous material because neutron scattering on hydrogen nuclei bound in a molecule is affected by the molecular dynamics (characterized with internal energy modes which are comparable to the incident neutron energy). Granada's synthetic model for slow-neutron scattering is used. The complete up-dated formalism of calculation of the energy transfer scattering kernel after this model is presented in the paper. An influence of some minor variants within the model on the calculated differential and integral neutron parameters is shown. The theoretical energy-dependent scattering cross section (of Plexiglas) is compared to experimental results. A particular attention is paid to the calculation of the diffusion cooling coefficient. A solution of an equation, which determines the

Parallel diffusion length on thermal neutrons in rod type lattices

International Nuclear Information System (INIS)

Ahmed, T.; Siddiqui, S.A.M.M.; Khan, A.M.

1981-11-01

Calculation of diffusion lengths of thermal neutrons in lead-water and aluminum water lattices in direction parallel to the rods are performed using one group diffusion equation together with Shevelev transport correction. The formalism is then applied to two practical cases, the Kawasaki (Hitachi) and the Douglas point (Candu) reactor lattices. Our results are in good agreement with the observed values. (author)

Experimental subcritical facility driven by D-D/D-T neutron generator at BARC, India

Energy Technology Data Exchange (ETDEWEB)

Sinha, Amar, E-mail: image@barc.gov.in; Roy, Tushar; Kashyap, Yogesh; Ray, Nirmal; Shukla, Mayank; Patel, Tarun; Bajpai, Shefali; Sarkar, P.S.; Bishnoi, Saroj

2015-05-01

Highlights: •Experimental subcritical facility BRAHMMA coupled to D-D/D-T neutron generator. •Preliminary results of PNS experiments reported. •Feynman-alpha noise measurements explored with continuous source. -- Abstract: The paper presents design of an experimental subcritical assembly driven by D-D/D-T neutron and preliminary experimental measurements. The system has been developed for investigating the static and dynamic neutronic properties of accelerator driven sub-critical systems. This system is modular in design and it is first in the series of subcritical assemblies being designed. The subcritical core consists of natural uranium fuel with high density polyethylene as moderator and beryllium oxide as reflector. The fuel is embedded in high density polyethylene moderator matrix. Estimated k{sub eff} of the system is ∼0.89. One of the unique features of subcritical core is the use of Beryllium oxide (BeO) as reflector and HDPE as moderator making the assembly a compact modular system. The subcritical core is coupled to Purnima Neutron Generator which works in D-D and D-T mode with both DC and pulsed operation. It has facility for online source strength monitoring using neutron tagging and programmable source modulation. Preliminary experiments have been carried out for spatial flux measurement and reactivity estimation using pulsed neutron source (PNS) techniques with D-D neutrons. Further experiments are being planned to measure the reactivity and other kinetic parameters using noise methods. This facility would also be used for carrying out studies on effect of source importance and measurement of source multiplication factor k{sub s} and external neutron source efficiency φ{sup ∗} in great details. Experiments with D-T neutrons are also underway.

A comparison of Nodal methods in neutron diffusion calculations

Energy Technology Data Exchange (ETDEWEB)

Tavron, Barak [Israel Electric Company, Haifa (Israel) Nuclear Engineering Dept. Research and Development Div.

1996-12-01

The nuclear engineering department at IEC uses in the reactor analysis three neutron diffusion codes based on nodal methods. The codes, GNOMERl, ADMARC2 and NOXER3 solve the neutron diffusion equation to obtain flux and power distributions in the core. The resulting flux distributions are used for the furl cycle analysis and for fuel reload optimization. This work presents a comparison of the various nodal methods employed in the above codes. Nodal methods (also called Coarse-mesh methods) have been designed to solve problems that contain relatively coarse areas of homogeneous composition. In the nodal method parts of the equation that present the state in the homogeneous area are solved analytically while, according to various assumptions and continuity requirements, a general solution is sought out. Thus efficiency of the method for this kind of problems, is very high compared with the finite element and finite difference methods. On the other hand, using this method one can get only approximate information about the node vicinity (or coarse-mesh area, usually a feel assembly of a 20 cm size). These characteristics of the nodal method make it suitable for feel cycle analysis and reload optimization. This analysis requires many subsequent calculations of the flux and power distributions for the feel assemblies while there is no need for detailed distribution within the assembly. For obtaining detailed distribution within the assembly methods of power reconstruction may be applied. However homogenization of feel assembly properties, required for the nodal method, may cause difficulties when applied to fuel assemblies with many absorber rods, due to exciting strong neutron properties heterogeneity within the assembly. (author).

Study of the radiation around a high energy accelerator. Production and scattering of cascade neutrons; Etude du rayonnement autour d'un accelerateur de haute energie. Production et diffusion des neutrons de cascade

Energy Technology Data Exchange (ETDEWEB)

Tardy-Joubert, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1966-03-01

The cascade induced in protective screens by a 3 GeV proton beam has been studied using activation detectors; the results have been compared with the cosmic neutron spectrum in the atmosphere. A study of the secondary neutron spectrum has made, it possible to obtain the distribution of the dose and to determine the maximum permissible fluxes expressed in terms of the energy, taking into account all the daughter products present. The dose calculated has been checked experimentally. The proportion of cascade neutrons has been studied using the idea of an imaginary source. The parameters which have to be introduced into the general equations to take into account scattering in the the air have been determined. (author) [French] La cascade induite dans les ecrans de protection par un faisceau de protons de 3 GeV a ete etudiee au moyen de detecteurs a activation et la comparaison a ete faite avec le spectre des neutrons cosmiques dans l'atmosphere. L'etude du spectre des neutrons secondaires a permis de preciser la distribution de la dose et de determiner les flux maximaux admissibles qui sont exprimes en fonction de l'energie, en tenant compte de l'ensemble des descendants presents. La dose calculee a ete verifiee experimentalement. La propagation des neutrons de cascade a ete etudiee en introduisant la notion de source fictive. Les parametres a introduire dans les equations generales pour rendre compte de la diffusion dans l'air ont ete determines. (auteur)

Fusion spectrum neutron source computation in "6LiD convertor for HFETR

International Nuclear Information System (INIS)

Sun Shouhua; Hu Yifei; Ye Bin

2014-01-01

A computation model of 14 MeV neutron from the "6LiD convertor has been established, the 14 MeV neutron sources and flux in the irradiation samples from the "6LiD convertor and the core have been computed separately, the neutron spectrum in the irradiation samples have been computed, too. The results show that the neutron sources that over 13 MeV account for 1 MeV above in the "6LiD convertor is 25.7%, 24.6% respectively, 14 MeV neutron sources get 4.31 × 10"1"3 n_T·s"-"1, 3.34 × 10"1"3 n_T·s"-"1, 14 MeV neutron flux get 2.66 × 10"1"0 n_T·cm"-"2·s"-"1, 3.53 × 10"1"0 n_T·cm"-"2·s"-"1, as He and H_2O charged in the irradiation capsule. (authors)

Individual and combined influence of ACE and ACTN3 genes on muscle phenotypes in Polish athletes.

Science.gov (United States)

Orysiak, Joanna; Mazur-Różycka, Joanna; Busko, Krzysztof; Gajewski, Jan; Szczepanska, Beata; Malczewska-Lenczowska, Jadwiga

2017-02-08

The aim of this study was to examine the association between ACE and ACTN3 genes, independently or in combination, and muscle strength and power in male and female athletes. The study involved 398 young male (n=266) and female (n=132) athletes representing various sport disciplines (ice hockey, canoeing, swimming, volleyball). All were Caucasians. The following measurements were taken: height of jump and mechanical power in countermovement jump (CMJ) and spike jump (SPJ), and muscle strength of 10 muscle groups (flexors and extensors of the elbow, shoulder, hip, knee and trunk). The ID polymorphism of ACE and the R577X polymorphism of ACTN3 were typed using PCR (polymerase chain reaction) and PCR-RFLP (polymerase chain reaction - restriction fragment length polymorphism), respectively. The genotype distribution of the ACE and ACTN3 genes did not differ significantly between groups of athletes for either sex. There was no association between ACE and ACTN3 genotypes (alone or in combination) and sum of muscle strength, height of jump or mechanical power in both jump tests (CMJ and SPJ) for male and female athletes. These findings do not support an influential role of the ACE and ACTN3 genes in determining power/strength performance of elite athletes.

ACE genotype, phenotype and all-cause mortality in different cohorts of patients with type 1 diabetes

DEFF Research Database (Denmark)

Færch, Louise H; Sejling, Anne-Sophie; Lajer, Maria

2015-01-01

AIMS: Carrying the D-allele of the angiotensin-converting enzyme (ACE) I/D polymorphism and high ACE activity are prognostic factors in diabetic nephropathy, which predicts mortality in type 1 diabetes. We studied the association between the ACE D-allele and ACE phenotype and long-term all-cause ...

Towards a 3-D magnetometry by neutron reflectometry

Energy Technology Data Exchange (ETDEWEB)

Fermon, C. [CEA/Saclay, Dept. de Recherche sur l' Etat Condense, les Atomes et les Molecules (DRECAM), 91 - Gif-sur-Yvette (France); Gilles, B. [Ecole Nationale Superieure d' Electrochimie et d' Electrometallurgie, 38 - Grenoble (France). Lab. de Thermodynamique et Physico-Chimie Metallurgiques; Marty, A. [CEA Grenoble, Dept. de Recherche Fondamentale sur la Matiere Condensee (DRFMC), 38 (France); Ott, F.; Menelle, A. [Laboratoire Leon Brillouin (LLB) - CEA/Saclay, 91 - Gif-sur-Yvette (France)

1998-07-01

Polarised Neutron reflectometry with spin analysis allows one to probe the in-depth magnetic profiles of thin films down to about 100 nm. Analysis of specular reflections gives access to the in-plane vectorial absolute magnetic moment. Off-specular reflectometry gives information about lateral contrasts with typical lengths ranging from 5 {mu}m to 100 {mu}m. Furthermore, surface diffraction at grazing angle gives access to transverse dimensions between 10 nm and 300 nm with a resolution in that direction of several nm. The combination of these 3 techniques applied to thin magnetic objects like thin films, arrays of lines or arrays of dots, leads to 3-D patterns in the reciprocal space. The method is extremely sensitive while giving the average on a rather large surface. Such a technique is therefore not applicable for the study of a single magnetic dot, but it generates unique results in several cases including patterns of domain walls in thin films with perpendicular anisotropy, arrays of magnetic dots, patterned fines in magnetic thin films. (authors)

Multigroup neutron transport equation in the diffusion and P{sub 1} approximation

Energy Technology Data Exchange (ETDEWEB)

Obradovic, D [Boris Kidric Institute of nuclear sciences Vinca, Belgrade (Yugoslavia)

1970-07-01

Investigations of the properties of the multigroup transport operator, width and without delayed neutrons in the diffusion and P{sub 1} approximation, is performed using Keldis's theory of operator families as well as a technique . recently used for investigations into the properties of the general linearized Boltzmann operator. It is shown that in the case without delayed neutrons, multigroup transport operator in the diffusion and P{sub 1} approximation possesses a complete set of generalized eigenvectors. A formal solution to the initial value problem is also given. (author)

Quasi-elastic neutron scattering studies of the diffusion of hydrogen in metals

Energy Technology Data Exchange (ETDEWEB)

Ross, D K [Birmingham Univ. (UK). School of Physics and Space Research

1989-01-01

Quasi-elastic neutron scattering provides a uniquely detailed way of investigating microscopic models for diffusion in lattice gases. In the present paper we discuss extensions of the original Chudley-Elliott model to cover systems containing high concentrations of interacting particles for both the incoherent and coherent cases. In the former case, the peak width is changed by site blocking and by interactions and its shape is altered by correlation effects between successive jumps. In the coherent case, although interactions introduce different correlation effects, the most important changes are due to the short-range order caused by the interactions. A simple Mean Field theory is described which predicts peak narrowing where the diffuse scattering is at a maximum. Experimental tests of both coherent and incoherent theories are described for the case of {alpha}'NbD{sub x}. (orig.).

Quasi-elastic neutron scattering studies of the diffusion of hydrogen in metals

International Nuclear Information System (INIS)

Ross, D.K.

1989-01-01

Quasi-elastic neutron scattering provides a uniquely detailed way of investigating microscopic models for diffusion in lattice gases. In the present paper we discuss extensions of the original Chudley-Elliott model to cover systems containing high concentrations of interacting particles for both the incoherent and coherent cases. In the former case, the peak width is changed by site blocking and by interactions and its shape is altered by correlation effects between successive jumps. In the coherent case, although interactions introduce different correlation effects, the most important changes are due to the short-range order caused by the interactions. A simple Mean Field theory is described which predicts peak narrowing where the diffuse scattering is at a maximum. Experimental tests of both coherent and incoherent theories are described for the case of α'NbD x . (orig.)

A D-D/D-T fusion reaction based neutron generator system for liver tumor BNCT

International Nuclear Information System (INIS)

Koivunoro, H.; Lou, T.P.; Leung, K. N.; Reijonen, J.

2003-01-01

Boron-neutron capture therapy (BNCT) is an experimental radiation treatment modality used for highly malignant tumor treatments. Prior to irradiation with low energetic neutrons, a 10B compound is located selectively in the tumor cells. The effect of the treatment is based on the high LET radiation released in the 10 B(n,α) 7 Li reaction with thermal neutrons. BNCT has been used experimentally for brain tumor and melanoma treatments. Lately applications of other severe tumor type treatments have been introduced. Results have shown that liver tumors can also be treated by BNCT. At Lawrence Berkeley National Laboratory, various compact neutron generators based on D-D or D-T fusion reactions are being developed. The earlier theoretical studies of the D-D or D-T fusion reaction based neutron generators have shown that the optimal moderator and reflector configuration for brain tumor BNCT can be created. In this work, the applicability of 2.5 MeV neutrons for liver tumor BNCT application was studied. The optimal neutron energy for external liver treatments is not known. Neutron beams of different energies (1eV < E < 100 keV) were simulated and the dose distribution in the liver was calculated with the MCNP simulation code. In order to obtain the optimal neutron energy spectrum with the D-D neutrons, various moderator designs were performed using MCNP simulations. In this article the neutron spectrum and the optimized beam shaping assembly for liver tumor treatments is presented

Alu insertion/deletion of ACE gene polymorphism might not affect ...

African Journals Online (AJOL)

Widodo

2016-09-03

Sep 3, 2016 ... a Biology Department, Faculty of Mathematics and Natural Sciences, Brawijaya ... Subjects and methods: The serum bradykinin and I/D polymorphism have been ..... Japanese hypertensive patients receiving an ACE inhibitor.

Polymorphisms in ACE and ACTN3 Genes and Blood Pressure Response to Acute Exercise in Elite Male Athletes from Serbia.

Science.gov (United States)

Durmic, Tijana S; Zdravkovic, Marija D; Djelic, Marina N; Gavrilovic, Tamara D; Djordjevic Saranovic, Slavica A; Plavsic, Jadranka N; Mirkovic, Sanja V; Batinic, Djordje V; Antic, Milena N; Mihailovic, Zoran R; Atanasijevic, Nikola G; Mileusnic, Milan J; Stojkovic, Oliver V

2017-12-01

Physiological adaptations to various types of prolonged and intensive physical activity, as seen in elite athletes from different sports, include changes in blood pressure (BP) response to acute exercise. Also, functional polymorphisms of the angiotensin I converting enzyme (ACE) and alfa-actinin-3 (ACTN3) genes are shown to be associated with BP parameters changes, both in athletes and sedentary population. In this study, an Alu insertion (I)/deletion (D) polymorphism in ACE gene, as well as nonsense mutation in the gene encoding ACTN3 have been scored in 107 elite Serbian athletes classified according to their sporting discipline to power/sprint (short distance runners/swimmers), endurance (rowers, footballers, middle-distance swimmers) or mixed sports (water polo, handball, volleyball players). Presence of nonfunctional allele in ACTN3 is associated with significantly increased maximal systolic BP (SBPmax, p = 0.04). Athletes with Alu insertion in ACE had significantly (p = 0.006) larger decline of systolic BP after 3 minutes of recovery (SBPR3), calculated as the percentage of maximal SBP response during exercise stress testing. Concomitant presence of non-functional variant in ACTN3 gene decreased this beneficiary effect of ACE mutation on SBPR3. Long term enrollment in power/sprint sports significantly increased resting diastolic BP (DBPrest: 74 mmHg) and SBPmax (197 mmHg) and improved SBPR3 (74.8%) compared to enrolment in endurance (72 mmHg; 178 mmHg; 81.1%) and mixed sports (69 mmHg; 185 mmHg; 80.0%). Lack of the effect of genotype by sport interaction on BP parameters suggests that the long-term effects of different disciplines on BP are not mediated by these two genes.

Radiative capture of neutrons by deuterons n+d → 3H+γ and P-odd nuclear forces

International Nuclear Information System (INIS)

Rekalo, M.P.

1987-01-01

P odd polarization phenomena in neutron radiative capture with deuterons, n+d → 3 H+γ have been studied. It is shown, that in a general case during collisions of arbitrarily polarized neutrons with a deuteron target characterized with vector and tensor polarizations, 18 different P odd asymmetries of gamma quanta angular distribution appear. P odd contribution to density matrix of gamma quanta produced in polarized neutron capture with nonpolarized deuterons is determined by 8 substantial structural functions and P odd dependence of photon Stokes parameters on deuteron tensor polarization is characterized in a general case with ten structure functions. The number of P odd correlations decreases when capturing slow neutrons

Domain decomposition methods for the mixed dual formulation of the critical neutron diffusion problem; Methodes de decomposition de domaine pour la formulation mixte duale du probleme critique de la diffusion des neutrons

Energy Technology Data Exchange (ETDEWEB)

Guerin, P

2007-12-15

The neutronic simulation of a nuclear reactor core is performed using the neutron transport equation, and leads to an eigenvalue problem in the steady-state case. Among the deterministic resolution methods, diffusion approximation is often used. For this problem, the MINOS solver based on a mixed dual finite element method has shown his efficiency. In order to take advantage of parallel computers, and to reduce the computing time and the local memory requirement, we propose in this dissertation two domain decomposition methods for the resolution of the mixed dual form of the eigenvalue neutron diffusion problem. The first approach is a component mode synthesis method on overlapping sub-domains. Several Eigenmodes solutions of a local problem solved by MINOS on each sub-domain are taken as basis functions used for the resolution of the global problem on the whole domain. The second approach is a modified iterative Schwarz algorithm based on non-overlapping domain decomposition with Robin interface conditions. At each iteration, the problem is solved on each sub domain by MINOS with the interface conditions deduced from the solutions on the adjacent sub-domains at the previous iteration. The iterations allow the simultaneous convergence of the domain decomposition and the eigenvalue problem. We demonstrate the accuracy and the efficiency in parallel of these two methods with numerical results for the diffusion model on realistic 2- and 3-dimensional cores. (author)

Incoherent neutron scattering functions for random jump diffusion in bounded and infinite media

International Nuclear Information System (INIS)

Hall, P.L.; Ross, D.K.

1981-01-01

The incoherent neutron scattering function for unbounded jump diffusion is calculated from random walk theory assuming a gaussian distribution of jump lengths. The method is then applied to calculate the scattering function for spatially bounded random jumps in one dimension. The dependence on momentum transfer of the quasi-elastic energy broadenings predicted by this model and a previous model for bounded one-dimensional continuous diffusion are calculated and compared with the predictions of models for diffusion in unbounded media. The one-dimensional solutions can readily be generalized to three dimensions to provide a description of quasi-elastic scattering of neutrons by molecules undergoing localized random motions. (author)

VSOP, Neutron Spectra, 2-D Flux Synthesis, Fuel Management, Thermohydraulics Calculation

International Nuclear Information System (INIS)

Teuchert, E.; Haas, K.A.

1995-01-01

1 - Description of problem or function: VSOP (Very Superior Old Programs) is a system of codes linked together for the simulation of reactor life histories. It comprises neutron cross section libraries and processing routines, repeated neutron spectrum evaluation, 2-D and 3-D diffusion calculation, depletion and shut-down features, in- core and out-of-pile fuel management, fuel cycle cost analysis, and thermal hydraulics (steady state and transient). Various techniques have been employed to accelerate the iterative processes and to optimize the internal data transfer. The code system has been used extensively for comparison studies of thermal reactors, their fuel cycles, thermal transients, and safety assessment. Besides its use in research and development work for the Gas Cooled High Temperature Reactor, the system has been applied successfully to Light Water and Heavy Water Reactors, MAGNOX, and RBMK. 2 - Method of solution: The nuclear data for 184 isotopes are contained in two libraries. Fast and epithermal data in a 68 group GAM-I structure have been prepared mainly from ENDF/B-V and JEF-1. Resonance cross section data are given as input. Thermal data in a 30 group THERMOS structure have been collapsed from a 96 group THERMALIZATION (GATHER) library by a relevant neutron energy spectrum generated by the THERMALIZATION code. Graphite scattering matrices are based on the Young phonon spectrum in graphite. The neutron spectrum is calculated by a combination of the GAM and THERMOS codes. They can simultaneously be employed for many core regions differing in temperature, burnup, and fuel element lay-out. The thermal cell code THERMOS has been extended to treat the grain structure of the coated particles inside the fuel elements, and the epithermal GAM code uses modified cross sections for the resonance absorbers prepared from double heterogeneous ZUT-DGL calculations. The diffusion module of the code is CITATION with 2 - 8 energy groups. It provides the neutron

Antioxidant, ACE-Inhibitory and antibacterial activities of Kluyveromyces marxianus protein hydrolysates and their peptide fractions

Directory of Open Access Journals (Sweden)

Mahta Mirzaeia

2016-07-01

Full Text Available Background: There has been evidence that proteins are potentially excellent source of antioxidants, antihypertensive and antimicrobial peptides, and that enzymatic hydrolysis is an effective method to release these peptides from protein molecules. The functional properties of protein hydrolysates depends on the protein substrate, the specificity of the enzymes, the conditions used during proteolysis, degree of hydrolysis, and the nature of peptides released including molecular weight, amino acid composition, and hydrophobicity. Context and purpose of this study: The biomass of Kluyveromyces marxianus was considered as a source of ACE inhibitory, antioxidant and antimicrobial peptides. Results: Autolysis and enzymatic hydrolysis were completed respectively, after 96 h and 5 h. Overall, trypsin (18.52% DH and chymotrypsin (21.59% DH treatments were successful in releasing antioxidant and ACE inhibitory peptides. Autolysate sample (39.51% DH demonstrated poor antioxidant and ACE inhibitory activity compared to trypsin and chymotrypsin hydrolysates. The chymotrypsin 3-5 kDa (301.6±22.81 μM TE/mg protein and trypsin < 3 kDa (280.16±39.16 μM TE/mg protein permeate peptide fractions showed the highest DPPH radical scavenging activity. The trypsin <3 kDa permeate peptide fraction showed the highest ABTS radical scavenging (1691.1±48.68 μM TE/mg protein and ACE inhibitory (IC50=0.03±0.001 mg/mL activities. The fraction (MW=5-10 kD obtained after autolysis treatment showed antibacterial activity against St. aureus and Lis. monocytogenes in well diffusion screening. The minimum inhibitory concentration (MIC value was 13.3 mg/mLagainst St. aureus and Lis. monocytogenes calculated by turbidimetric assay and it showed bactericidal activity against St. aureus at 21.3 mg/mL protein concentration. Conclusions: Altogether, the results of this study reveal that K. marxianus proteins contain specific peptides in their sequences which can be released by

Experiments on the thermalization of slow neutrons by liquid hydrogen (1962); Experience de thermalisation de neutrons lents par de l'hydrogene liquide (1962)

Energy Technology Data Exchange (ETDEWEB)

Cribier, D; Jacrot, B; Lacaze, A; Roubeau, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Institut Fourier, 38 - Grenoble (France)

1962-07-01

In order to increase the flux of neutrons of long wave-length ({lambda} > 4 A) emerging from a channel in the EL-3, a liquid hydrogen device was introduced into a channel of the reactor (Channel H{sub 1}). The principle of the device is simple. A volume of liquid hydrogen is introduced as close as possible to the reactor core into a region of intense isotropic flux. This hydrogen slows down the slow neutrons; because of the very small mean free diffusion path of slow in hydrogen, this slowing down is considerable even in a small volume of liquid hydrogen, and the spectrum temperature of neutrons emerging from the volume of liquid hydrogen can therefore be shifted. The intensity gain for neutrons with a wave length {lambda}, is a G ({lambda}) function which, for perfect thermalization and ignoring capture, is expressed by: G ({lambda}) = 225 exp (- 45.3/{lambda}{sup 2}), assuming a temperature of 300 deg. K for the neutrons before cooling and is 20 deg. K after cooling. For a wave-length of 5 A, the theoretical maximum gain of thus about 37. (authors) [French] Dans le but d'accroitre le flux des neutrons de grande longueur d'onde ({lambda} > 4 A) sortant d'un canal de la pile EL-3, un dispositif a hydrogene liquide a ete introduit dans un canal de la pile (canal H{sub 1}). Le principe du dispositif est simple. Un volume d'hydrogene liquide est introduit le plus pres possible du coeur de ia pile dans une region de flux intense et isotrope. Les neutrons lents sont ralentis par cet hydrogene; a cause du tres faible libre parcours moyen de diffusion des neutrons lents dans l'hydrogene, ce ralentissement est important meme dans un faible volume d'hydrogene liquide et l'on peut ainsi deplacer la temperature du spectre des neutrons sortant du volume d'hydrogene liquide. Le gain en intensite des neutrons de longueur d'onde {lambda} est une fonction G ({lambda}) qui pour une thermalisation parfaite et en negligeant la capture, s'exprime par: G ({lambda}) = 225 exp (- 45.3

Neutron scattering for investigation into the connection between phonons and diffusion in metallic systems

International Nuclear Information System (INIS)

Herzig, C.

1995-01-01

For examining the connection between the diffusion systematics and the lattice dynamics of the body-centered cubic metals, the temperature dependence of the self-diffusion (radiotracer technique) and the phonon dispersion (neutron scattering) have been measured in selected systems. In continuation of previous studies, the goal of the examinations reported was to put the earlier developed phonon-related diffusion model on a broader experimental basis, in order to perform verifying analyses. The phonon dispersion of the group 5 metal Nb has been measured up to high temperatures. In contrast to the values measured for the group 4 (β-Zr) and group 6 (Cr) metals, the dispersion in Nb revealed an only very weak temperature dependence. The exceptional case of the bcc β-Tl has been examined by measuring the diffusion and the dispersion in the β-T 83 In 17 alloy. Significant deviations from the conditions in the bcc transition metals have been found. Self-diffusion has been measured for the first time in Ba and β-Sc. Their diffusion systematics correlate with electron configuration. The influence of the d-electron concentration on the diffusion systematics has been measured in Ti-Mo and Hf-Nb alloys, the results backing the predictions of the phonon-related diffusion model. (orig.) [de

The use of multi-energy-group neutron diffusion theory to numerically evaluate the relative utility of three dial-detector neutron porosity well logging tools

International Nuclear Information System (INIS)

Zalan, T.A.

1988-01-01

Multi-energy-group neutron diffusion theory is used to numerically evaluate the utility of two different dual-detector neutron porosity logging devices, a 14 MeV (accelerator) neutron source - epithermal neutron detector device and a 4 MeV neutron source - capture gamma-ray detector device, relative to the traditional 4 MeV neutron source - thermal neutron detector device. Fast and epithermal neutron diffusion parameters are calculated using Monte Carlo - derived neutron flux distributions. Thermal parameters are calculated from tabulated cross sections. An existing analytical method to describe the transport of gamma-rays through common earth materials is modified in order to accommodate the modeling of the 4 MeV neutron - capture gamma-ray device. The 14 MeV neutron - epithermal neutron device is found to be less sensitive to porosity than the 4 MeV neutron - capture gamma-ray device, which in turn is found to be less sensitive to porosity than the traditional 4 MeV neutron - thermal neutron device. Salinity effects are found to be comparable for the 4 MeV neutron - capture gamma-ray and 4 MeV neutron - thermal neutron devices. The 4 MeV neutron capture gamma-ray measurement is found to be deepest investigating

Neutron and x-ray scattering study of phonon dispersion and diffuse scattering in (Na ,Bi ) Ti O3-x BaTi O3 single crystals near the morphotropic phase boundary

Science.gov (United States)

Luo, Chengtao; Bansal, Dipanshu; Li, Jiefang; Viehland, Dwight; Winn, Barry; Ren, Yang; Li, Xiaobing; Luo, Haosu; Delaire, Olivier

2017-11-01

Neutron and x-ray scattering measurements were performed on (N a1 /2B i1 /2 ) Ti O3-x at %BaTi O3 (NBT-x BT ) single crystals (x =4 , 5, 6.5, and 7.5) across the morphotropic phase boundary (MPB), as a function of both composition and temperature, and probing both structural and dynamical aspects. In addition to the known diffuse scattering pattern near the Γ points, our measurements revealed new, faint superlattice peaks, as well as an extensive diffuse scattering network, revealing a short-range ordering of polar nanoregions (PNR) with a static stacking morphology. In samples with compositions closest to the MPB, our inelastic neutron scattering investigations of the phonon dynamics showed two unusual features in the acoustic phonon branches, between the superlattice points, and between the superlattice points and Γ points, respectively. These critical elements are not present in the other compositions away from the MPB, which suggests that these features may be related to the tilt modes coupling behavior near the MPB.

Ohmic ion temperature and thermal diffusivity profiles from the JET neutron emission profile monitor

Energy Technology Data Exchange (ETDEWEB)

Esposito, B. (ENEA, Frascati (Italy). Centro Ricerche Energia); Marcus, F.B.; Conroy, S.; Jarvis, O.N.; Loughlin, M.J.; Sadler, G.; Belle, P. van (Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking); Adams, J.M.; Watkins, N. (AEA Industrial Technology, Harwell (United Kingdom))

1993-10-01

The JET neutron emission profile monitor was used to study ohmically heated deuterium discharges. The radial profile of the neutron emissivity is deduced from the line-integral data. The profiles of ion temperature, T[sub i], and ion thermal diffusivity, [chi][sub i], are derived under steady-state conditions. The ion thermal diffusivity is higher than, and its scaling with plasma current opposite to, that predicted by neoclassical theory. (author).

Ohmic ion temperature and thermal diffusivity profiles from the JET neutron emission profile monitor

International Nuclear Information System (INIS)

Esposito, B.

1993-01-01

The JET neutron emission profile monitor was used to study ohmically heated deuterium discharges. The radial profile of the neutron emissivity is deduced from the line-integral data. The profiles of ion temperature, T i , and ion thermal diffusivity, χ i , are derived under steady-state conditions. The ion thermal diffusivity is higher than, and its scaling with plasma current opposite to, that predicted by neoclassical theory. (author)

Domain decomposition methods for the mixed dual formulation of the critical neutron diffusion problem

International Nuclear Information System (INIS)

Guerin, P.

2007-12-01

The neutronic simulation of a nuclear reactor core is performed using the neutron transport equation, and leads to an eigenvalue problem in the steady-state case. Among the deterministic resolution methods, diffusion approximation is often used. For this problem, the MINOS solver based on a mixed dual finite element method has shown his efficiency. In order to take advantage of parallel computers, and to reduce the computing time and the local memory requirement, we propose in this dissertation two domain decomposition methods for the resolution of the mixed dual form of the eigenvalue neutron diffusion problem. The first approach is a component mode synthesis method on overlapping sub-domains. Several Eigenmodes solutions of a local problem solved by MINOS on each sub-domain are taken as basis functions used for the resolution of the global problem on the whole domain. The second approach is a modified iterative Schwarz algorithm based on non-overlapping domain decomposition with Robin interface conditions. At each iteration, the problem is solved on each sub domain by MINOS with the interface conditions deduced from the solutions on the adjacent sub-domains at the previous iteration. The iterations allow the simultaneous convergence of the domain decomposition and the eigenvalue problem. We demonstrate the accuracy and the efficiency in parallel of these two methods with numerical results for the diffusion model on realistic 2- and 3-dimensional cores. (author)

Self and transport diffusivity of CO2 in the metal-organic framework MIL-47(V) explored by quasi-elastic neutron scattering experiments and molecular dynamics simulations.

Science.gov (United States)

Salles, Fabrice; Jobic, Hervé; Devic, Thomas; Llewellyn, Philip L; Serre, Christian; Férey, Gérard; Maurin, Guillaume

2010-01-26

Quasi-elastic neutron scattering measurements are combined with molecular dynamics simulations to determine the self-diffusivity, corrected diffusivity, and transport diffusivity of CO(2) in the metal-organic framework MIL-47(V) (MIL = Materials Institut Lavoisier) over a wide range of loading. The force field used for describing the host/guest interactions is first validated on the thermodynamics of the MIL-47(V)/CO(2) system, prior to being transferred to the investigations of the dynamics. A decreasing profile is then deduced for D(s) and D(o) whereas D(t) presents a non monotonous evolution with a slight decrease at low loading followed by a sharp increase at higher loading. Such decrease of D(t) which has never been evidenced in any microporous systems comes from the atypical evolution of the thermodynamic correction factor that reaches values below 1 at low loading. This implies that, due to intermolecular interactions, the CO(2) molecules in MIL-47(V) do not behave like an ideal gas. Further, molecular simulations enabled us to elucidate unambiguously a 3D diffusion mechanism within the pores of MIL-47(V).

Contribution to the study of 14 MeV neutron scattering by {sup 12}C using a time-of-flight spectrometer (1963); Contribution a l'etude de la diffusion des neutrons de 14 MeV par {sup 12}C, a l'aide d'un spectrometre a temps de vol (1963)

Energy Technology Data Exchange (ETDEWEB)

Perrin, P [Commisariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1963-07-15

Experimental measurements of 14 MeV fast neutrons scattering by {sup 12}C by time-flight spectrometer, with a 1.7 n. sec over-all resolution. The excitation of the 7.65 MeV level is observed. (author) [French] Etude experimentate de la diffusion par {sup 12}C des neutrons rapides de 14 MeV a l'aide d'un spectrometre de resolution totale de 17 n/s. Observation de l'excitation du niveau 0+ de 7,65 MeV. (auteur)

An extension of diffusion theory for thermal neutrons near boundaries; Extension del campo de validez de la teoria de difusion para neutrones termico en las proximidades de bordes

Energy Technology Data Exchange (ETDEWEB)

Alvarez Rivas, J L

1963-07-01

The distribution of thermal neutron flux has been measured inside and outside copper rods of several diameters, immersed in water. It has been found that these distributions can be calculated by means of elemental diffusion theory if the value of the coefficient of diffusion is changed. this parameter is truly a diffusion coefficient, which now also depends on the diameter of the rod. Through a model an expression of this coefficient is introduced which takes account of the measurements of the author and of those reported in PUGC P/928 (1995), ANL-5872 (1959), DEGR 319 (D) (1961). This model could be extended also to plane geometry. (Author) 19 refs.

Improvements in fast-neutron spectroscopy methods (1961); Amelioration des methodes de spectrometrie des neutrons rapides (1961)

Energy Technology Data Exchange (ETDEWEB)

Cambou, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-02-15

This research aimed at improving fast-neutron electronic detectors based on n-p elastic scattering. The first part concerns proportional counters; careful constructional methods have made it possible to plot mono-energetic neutron spectra in the range 700 keV - 3 MeV with a resolution of 7 per cent. The second part concerns scintillation counters: an organic scintillator and an inorganic scintillator covered with a thin layer of a scattering agent. An exact study of the types of scintillation has made it possible to develop efficient discriminator circuits. Different neutron spectra plotted in the presence of a strong gamma background are presented. The last part deals with the development of form discrimination methods for the study, in the actual beam, of the elastic scattering of 14.58 MeV electrons. With hydrogen, the distribution f ({phi}) of the recoil protons is f({phi}) = 1 + 0.034 cos {phi} + 0.042 cos{sup 2} {phi}. With tritium the scattering is strongly anisotropic; the curve representing the variation of the differential cross-section for the elastic scattering in the centre of mass system is obtained with a target containing 1 cm{sup 3} of tritium. (author) [French] Le travail a porte sur l'amelioration des detecteurs electroniques de neutrons rapides bases sur la diffusion elastique n-p. La premiere partie est relative aux compteurs proportionnels; des methodes soignees de fabrication ont permis des traces de spectres de neutrons monoenergetiques dans le domaine 700 keV - 3 MeV avec une resolution de 7 pour cent. La deuxieme partie est relative au compteur a scintillations; scintillateur organique et scintillateur mineral recouvert d'un diffuseur mince. Une etude precise des formes de scintillations a permis la mise au point de circuits discriminateurs efficaces. Differents spectres de neutrons traces en presence d'un fond gamma intense sont presentes. La derniere partie est relative a la mise en oeuvre des methodes de discrimination de forme pour l

Neutrons in a highly diffusive medium a new propulsion tool for deep space exploration?

CERN Document Server

Rubbia, Carlo

1998-01-01

The recently completed TARC Experiment at the CERN-PS has shown how it is possible to confine neutrons by diffusion in a limited volume of a highly transparent medium for very long times (tens of milliseconds), with correspondingly very long diffusive paths (> 60 m neutron path ÒwoundÓ within a ~ 60 cm effective radius). Assume an empty cavity is introduced inside the previous volume of diffusing medium. The inner walls of the cavity are covered with a thin layer of highly fissionable material, which acts as a neutron multiplying source. This configuration, called Òn-HohlraumÓ, is reminiscent of a classic black-body radiator, with the exception that now neutrons rather than photons are propagated. The flux can be sufficiently enhanced as to permit to reach criticality with a ~ 1 mm thick Americium deposit, corresponding to a mere 1100 atomic layers. Such a layer is so thin that the Fission Fragments (FF) exit freely into the cavity. The energy carried by FF can be recovered directly, thus making use of th...

Study on neutron diffusion and time dependence heat ina fluidized bed nuclear reactor

International Nuclear Information System (INIS)

Vilhena, M.T. de.

1988-01-01

The purpose of this work is to model the neutron diffusion and heat transfer for a Fluidized Bed Nuclear Reactor and its solution by Laplace Transform Technique with numerical inversion using Fourier Series. Also Gaussian quadrature and residues techniques were applied for numerical inversion. The neutron transport, diffusion, and point Kinetic equation for this nuclear reactor concept are developed. A matricial and Taylor Series methods are proposed for the solution of the point Kinetic equation which is a time scale problem of Stiff type

TORT-TD/ATTICA3D: a coupled neutron transport and thermal hydraulics code system for 3-D transient analysis of gas cooled high temperature reactors

International Nuclear Information System (INIS)

Lapins, J.; Seubert, A.; Buck, M.; Bader, J.; Laurien, E.

2011-01-01

Comprehensive safety studies of high temperature gas cooled reactors (HTR) require full three dimensional coupled treatments of both neutron kinetics and thermal-hydraulics. In a common effort, GRS and IKE developed the coupled code system TORT-TD/ATTICA3D for pebble bed type HTR that connects the 3-D transient discrete-ordinates transport code TORT-TD with the 3-D porous medium thermal-hydraulics code ATTICA3D. In this paper, the physical models and calculation capabilities of TORT-TD and ATTICA3D are presented, focusing on model improvements in ATTICA3D and extensions made in TORT-TD related to HTR application. For first applications, the OECD/NEA/NSC PBMR-400 benchmark has been chosen. Results obtained with TORT-TD/ATTICA3D will be shown for transient exercises, e.g. control rod withdrawal and a control rod ejection. Results are compared to other benchmark participants' solutions with special focus on fuel temperature modelling features of ATTICA3D. The provided “grey-curtain” nuclear cross section libraries have been used. First results on 3-D effects during a control rod withdrawal transient will be presented. (author)

Accounting for the thermal neutron flux depression in voluminous samples for instrumental neutron activation analysis

International Nuclear Information System (INIS)

Overwater, R.M.W.; Hoogenboom, J.E.

1994-01-01

At the Delft University of Technology Interfaculty Reactor Institute, a facility has been installed to irradiate cylindrical samples with diameters up to 15 cm and weights up to 50 kg for instrumental neutron activation analysis (INAA) purposes. To be able to do quantitative INAA on voluminous samples, it is necessary to correct for gamma-ray absorption, gamma-ray scattering, neutron absorption, and neutron scattering in the sample. The neutron absorption and the neutron scattering are discussed. An analytical solution is obtained for the diffusion equation in the geometry of the irradiation facility. For samples with known composition, the neutron flux--as a function of position in the sample--can be calculated directly. Those of unknown composition require additional flux measurements on which least-squares fitting must be done to obtain both the thermal neutron diffusion coefficient D s and the diffusion length L s of the sample. Experiments are performed to test the theory

Asymptotic neutron scattering laws for anomalously diffusing quantum particles