bluuebunny/crossref_metadata_2025_split huggingface dataset:
Examining the Effect of Gamma Radiation Exposure in Early Stage of Concrete Curing on its Strength and Long-Term Durability
Authors: Burnham Steven , Huang Long , Jevremovic Tatjana 
Published: October 2016

Hydration is a main process following mixing of cement with water, producing a chemical reaction between cement particles and water molecules known as Calcium-Silica-Hydroxide (C-S-H). The C-S-H acts as a binder between coarse and fine mix aggregates. During mixing, capillary voids are formed where water can easily become trapped. The van der Waals force being the principal source of strength between such compounds, voids become detrimental to long-term strength of concrete because they decrease the amount of surface area aggregate and cement particles have to come into contact with each other. An overall decrease in both pores size and their distribution in concrete increase density, therefore increasing the van der Waals force between these particles. In order to reduce capillary pores size and their distribution, in this paper we present a result from preliminary investigation on how gamma ray exposure during the early stages of the curing process affect the concrete mixture strength values. The gamma ray enhanced curing is expected to break the water molecules trapped in capillary pores into H+ and OH−, allowing these ions to escape and therefore result in densifying the concrete mixture.
Concrete cubes of 5cm3 in volumes are exposed to isotropic 137Cs gamma emitting source. The absorbed dose in cubes is measured as well as calculated using MCNP6. Each concrete cube is exposed to a 630 MBq 137Cs source for seven continuous days. The absorbed dose is experimentally measured using a Landauer nanoDot system. The average measured dose is 1.12 Gy at the front and 0.33 at the back of a concrete, totaling 0.79 Gy. The average measured dose is 0.98 Gy at the front and 0.29 Gy at the back, totaling 0.69 Gy of absorbed dose, thus showing a good agreement between the numerical predictions and experimental measurements.
Compressive strength of concrete mixes exposed to gamma rays during the curing time and those cured without exposure to gamma radiation are tested. Preliminary data shows that the average compressive strength for gamma ray enhanced curing of concrete mixes is in order of 9,000 psi while the average com-pressive strength for the cubes cured in dry air is on average about 5,000 psi. A number of new experiments is planed until the time of the Conference in providing more exact answer to the question: does gamma ray enhanced curing of concrete increase its strength and reduces the curing time?
Numerical Investigation of Flow Diffuser Optimization for a PWR Reactor With Code_Saturne: Analysis on EPR Type Reactor
Authors: Xu Tingting , Min Jiesheng , Chen Guofei , Delepine Samuel , Bellet Serge , Ge Jian , Tian Wenxi 
Published: October 2016

In order to provide scientific basis for new reactor design in terms of optimal Flow Diffuser, a study was launched on the analysis and investigation on flow distribution of existing flow diffuser design of five different reactors including EPR, VVER, Konvoi, APR+ and Westinghouse. The strategy is to change each time only the flow diffuser within the 1/5 scale BORA mock-up1. The authors consider that the optimal design needs to reach a homogeneous inlet core flow rate, which is defined as figures of merit. This study combines PIRT (Phenomena Identification and Ranking Table) methodology and Computational Fluid Dynamics (CFD) calculations to identify the optimal flow diffuser design.
This paper introduces main physical phenomena analysis with PIRT methodology to list the most important phenomena and parameters from cold legs to lower core plate which have a high level of influence on the flow distribution at reactor core inlet for EPR reactor type. CFD calculations are performed under the injection condition of 0.1 m3/s per cold leg at 1/5 scale BORA mock-up for EPR flow diffuser configuration. EDF in-house open-source codes are applied to perform CFD calculations including Salomé2 for pre-processing and postprocessing and Code_Saturne3 for solver.
Electric Power Supply of German NPPs: Defence in Depth, Protection Against External Hazards and Retrofitting as a Consequence of the Fukushima Accident
Authors: Meiss Sebastian A. 
Published: October 2016

The history of building and operating nuclear power plants (NPPs) in Germany dates back to the late 1950s and will come to an end in 2022. By then all NPPs still in operation will have to shut down in a defined sequence, according to the revisions made to the German Atomic Energy Act as a consequence of the accident at the Fukushima Dai-Ichi NPP. Nine out of 17 NPPs have already been shut down permanently as a consequence.
Due to the progress in science and technology, the design of the electrical power supply of German NPPs got more complex and hardened against various scenarios with time. The latest generation of NPPs built in Germany in the late 1980’s — the pressurized water reactor of type Konvoi — was designed with Defence in Depth in mind. They are connected to several voltage levels of the power grid and feature two layers of AC emergency power systems, each of which fulfills the n+2 redundancy criteria. The second of those layers is especially hardened against the influence of certain internal and external events and is part of an emergency control system which can keep the plant in a safe state autonomously for 10 hours under certain conditions.
With this being the state of science and technology at that time in Germany, most of the older NPPs in operation had been retrofitted by 2011 with systems that were designed to partially compensate for these plants’ weaker original design.
Various events such as the accident at the Chernobyl 4 NPP in 1986 and also the accident at the Fukushima Dai-Ichi NPP in 2011 led to changes in the German regulatory framework and recommendations to the NPPs for further retrofitting activities. In the regime of electrical power supply, the latest changes in requirements and corresponding retrofitting of the NPPs in operation include mobile diesel generators with corresponding, redundant feeding points, an enhanced coping capability for station blackouts with only DC-power left and measures to ensure bringing back AC-power within the available time.
In this presentation the author gives an overview over the historic development of the electric design in German NPPs and discuss details of the most recently added requirements on retrofitting — e.g. in the new regulatory framework — to enhance the robustness of the electrical power supply of those NPPs. An update on the progress on the actual retrofitting process of the German NPPs with respect to these new requirements is given.
Assessment of RANS Based CFD Methodology Using JAEA Fuel Assembly Experiment
Authors: Jeong Jae-Ho 
Published: October 2016

This paper presents an assessment results for the developed RANS (Reynolds Averaged Navier-Stokes simulation) based CFD (Computational Fluid Dynamics) methodology applicable to real scale 217-pin wire wrapped fuel assembly of the KAERI (Korea Atomic Energy Research Institute) PGSFR (Prototype Gen-IV Sodium-cooled Fast Reactor).
Complicated and vortical flow phenomena in the wire-wrapped fuel bundles were captured by a shear stress transport (SST) turbulence model, and by a vortex structure identification technique based on the critical point theory. The CFD results show good agreement with the JAEA experiment with the 127-pin wire-wrapped fuel assembly. The JAEA experiment study was implemented using water for validating pressure drop formulas in ASFRE code. The edge vortex structures are longitudinally developed, and have a higher axial velocity than corner vortex structures and wakes nearby pins and wires. The wire spacers locally induce a tangential flow by up to about 16 % of the axial velocity. The tangential flow in the corner and edge sub-channels is much stronger than that in the interior subchannels. The large-scale edge vortex structures have higher turbulence intensity and lower vorticity than the small-scale wakes. The corner vortex structures have lower turbulence intensity and vorticity than the small-scale wakes. The driving forces in the X-, Y-, and Z-directions are not only dependent on the axial velocity, but also significantly dependent on the angular position between the wire-spacer and rod, and the relative position between the wire-spacer and duct wall.
A Fuel Cycle and Core Design Analysis Method for New Cladding Acceptance Criteria Using PHISICS, RAVEN and RELAP5-3D
Authors: Alfonsi Andrea , Mesina George L. , Zoino Angelo , Rabiti Cristian 
Published: October 2016

The Nuclear Regulatory Commission (NRC) has considered revising the 10 CFR 50.46C rule [1] for analyzing reactor accident scenarios to take the effects of burn-up rate into account. Both maximum temperature and oxidation of the cladding must be cast as functions of fuel exposure in order to find limiting conditions, making safety margins dynamic limits that evolve with the operation and reloading of the reactor. In order to perform such new analysis in a reasonable computational time with good accuracy, INL (Idaho National Laboratory) has developed new multi-physics tools by combining existing codes and adding new capabilities. The PHISICS (Parallel Highly Innovative Simulation INL Code System) toolkit [2,3] for neutronic and reactor physics is coupled with RELAP5-3D [4] (Reactor Excursion and Leak Analysis Program) for the LOCA (Loss of Coolant Accident) analysis and RAVEN [5] for the PRA (Probabilistic Risk Assessment) and margin characterization analysis.
In order to perform this analysis, the sequence of RELAP5-3D input models had to get executed in a sequence of multiple input decks, each of them had to restart and slightly modify the previous model (in this case, on the neutronic side only) This new RELAP5-3D multi-deck processing capability has application to parameter studies and uncertainty quantification. The combined RAVEN/PHISICS/RELAP5-3D tool is used to analyze a typical PWR (Pressurized Water Reactor).
On Experimental Simulation of Passive Evaporation-and-Condensation Systems of Reactor Thermal Shielding
Authors: Gershuni Alexander N. , Nishchik Alexander P. , Pis’mennyi Evgeviy N. , Razumovskiy Victor G. , Pioro Igor L. 
Published: October 2016

Object of the study relates to passive safety systems of cooling, heat removal and thermal protection that operate as independent evaporation-condensation (EC) systems and could maintain required thermal conditions of the technological systems of nuclear power cycle. Reliability of the passive systems is provided by absence of moving parts and by their operation based on physical laws of nature, i.e., without any intervention of staff, power supply, and control signals.
One of the main features of these systems is their ultimate heat transferring ability. There are hydrodynamic limitations of heat transferring ability connected with provision of coolant circulation in vapor-condensate lines of transportation zone that could be combined into two groups: 1) the crises depending upon quantity and distribution of liquid phase; and 2) the crises affected by hydrodynamic interaction of liquid and vapor phases. The authors undertook investigation of various thermophysical factors limiting this ability, determined and analyzed its regularities, which depend upon thermodynamical conditions, transport ability of capillary structures (if any), and the interaction of vapor and liquid flows of HP coolant.
Heat transferring ability of a model of EC system of passive surface cooling and thermal shielding under the conditions of heat supply from radiating surface of reactor simulator to heat pipes as the elements of two-row screen was investigated.
The analysis and calculations made by the authors proved the possibility to create an efficient passive evaporation EC system of surface cooling and thermal shielding of reactor unit. Such a system has a number of advantages as compared with known active safety systems (e.g., autonomy, higher reliability, and operational safety), does not require emergency water resources, compressed air systems, numerous valves, etc.).
The tests were performed at vertical orientation of HP evaporation zone (condensation zone was above evaporation zone) as a part of the double-row screen. The heat pipe was tested at its location in each of two rows and at two options of condensation zone: vertical and inclined in transportation zone at 20° to horizon.
It was found that only insignificant circumferential nonisothermality of heat-pipe surface under steady one-side heat supply in evaporation zone took place. Quite satisfactory agreement of the experimental and predicted values of heat flux transmitted by heat pipes of two-row screen was obtained.
The investigation proved efficiency and reliability of EC system of surface cooling and thermal shielding of the reactor equipment.
In Vitro
Activities of Novel Azole Compounds ATTAF-1 and ATTAF-2 against Fluconazole-Susceptible and -Resistant Isolates of Candida Species
Authors: Fakhim Hamed , Emami Saeed , Vaezi Afsane , Hashemi Seyedeh Mahdieh , Faeli Leila , Diba Kambiz , Dannaoui Eric , Badali Hamid 
Published: October 2016

ABSTRACT

The
in vitro
activities of two novel azole compounds (aryl-1,2,4-triazol-3-ylthio analogues of fluconazole [ATTAFs]) and five comparator antifungal agents against 52 clinical
Candida
isolates from 5 different species were determined. The novel azole compounds had the lowest geometric mean MICs, followed by fluconazole. Moreover, combinations of these compounds with fluconazole exhibited synergistic effects against fluconazole-susceptible (22 of 23 isolates), fluconazole-susceptible dose-dependent (10 of 13 isolates), and fluconazole-resistant (1 of 16 isolates)
Candida
isolates.
Pharmacodynamics of Aerosolized Fosfomycin and Amikacin against Resistant Clinical Isolates of Pseudomonas aeruginosa and Klebsiella pneumoniae in a Hollow-Fiber Infection Model: Experimental Basis for Combination Therapy
Authors: Sime Fekade Bruck , Johnson Adam , Whalley Sarah , Santoyo-Castelazo Anahi , Montgomery A. Bruce , Walters Kathie Ann , Lipman Jeffrey , Hope William W. , Roberts Jason A. 
Published: October 2016

ABSTRACT

There has been a resurgence of interest in aerosolization of antibiotics for treatment of patients with severe pneumonia caused by multidrug-resistant pathogens. A combination formulation of amikacin-fosfomycin is currently undergoing clinical testing although the exposure-response relationships of these drugs have not been fully characterized. The aim of this study was to describe the individual and combined antibacterial effects of simulated epithelial lining fluid exposures of aerosolized amikacin and fosfomycin against resistant clinical isolates of
Pseudomonas aeruginosa
(MICs of 16 mg/liter and 64 mg/liter) and
Klebsiella pneumoniae
(MICs of 2 mg/liter and 64 mg/liter) using a dynamic hollow-fiber infection model over 7 days. Targeted peak concentrations of 300 mg/liter amikacin and/or 1,200 mg/liter fosfomycin as a 12-hourly dosing regimens were used. Quantitative cultures were performed to describe changes in concentrations of the total and resistant bacterial populations. The targeted starting inoculum was 10
8
CFU/ml for both strains. We observed that neither amikacin nor fosfomycin monotherapy was bactericidal against
P. aeruginosa
while both were associated with rapid amplification of resistant
P. aeruginosa
strains (about 10
8
to 10
9
CFU/ml within 24 to 48 h). For
K. pneumoniae
, amikacin but not fosfomycin was bactericidal. When both drugs were combined, a rapid killing was observed for
P. aeruginosa
and
K. pneumoniae
(6-log kill within 24 h). Furthermore, the combination of amikacin and fosfomycin effectively suppressed growth of resistant strains of
P. aeruginosa
and
K. pneumoniae
. In conclusion, the combination of amikacin and fosfomycin was effective at maximizing bacterial killing and suppressing emergence of resistance against these clinical isolates.
Screening the Pathogen Box for Identification of Candida albicans Biofilm Inhibitors
Authors: Vila Taissa , Lopez-Ribot Jose L. 
Published: October 2016

ABSTRACT

Candida albicans
remains the main causative agent of candidiasis, one of the most frequent nosocomial infections, with unacceptably high mortality rates. Biofilm formation is a major risk factor for invasive candidiasis, as
Candida
biofilms display high-level resistance to most antifungal agents. In this work we have screened the Pathogen Box chemical library (Medicines for Malaria Venture [MMV], Switzerland) in search for inhibitors of
C. albicans
biofilm formation. Our initial screen identified seven hits, and additional dose-response assays confirmed the biofilm-inhibitory activity of six of these small molecules. Three compounds, MMV688768, MMV687273, and MMV687807, were also able to reduce the metabolic activity of cells within preformed biofilms. Interestingly, the most potent of these, compound MMV688768, displayed increased antibiofilm activity compared to its activity against planktonic cultures, indicating that it may affect processes with a predominant role during the biofilm mode of growth. This compound demonstrated a high selectivity index when its antibiofilm activity was compared with its toxicity in liver hepatocellular cells.
In vitro
combination assays showed a synergistic interaction between compound MMV688768 and fluconazole against preformed biofilms. Overall, our results indicate that this compound may constitute a potential candidate for further clinical development.
Plasmodium falciparum Genetic Diversity in Continental Equatorial Guinea before and after Introduction of Artemisinin-Based Combination Therapy
Authors: Guerra Mónica , Neres Rita , Salgueiro Patrícia , Mendes Cristina , Ndong-Mabale Nicolas , Berzosa Pedro , de Sousa Bruno , Arez Ana Paula 
Published: October 2016

ABSTRACT

Efforts to control malaria may affect malaria parasite genetic variability and drug resistance, the latter of which is associated with genetic events that promote mechanisms to escape drug action. The worldwide spread of drug resistance has been a major obstacle to controlling
Plasmodium falciparum
malaria, and thus the study of the origin and spread of associated mutations may provide some insights into the prevention of its emergence. This study reports an analysis of
P. falciparum
genetic diversity, focusing on antimalarial resistance-associated molecular markers in two socioeconomically different villages in mainland Equatorial Guinea. The present study took place 8 years after a previous one, allowing the analysis of results before and after the introduction of an artemisinin-based combination therapy (ACT), i.e., artesunate plus amodiaquine. Genetic diversity was assessed by analysis of the
Pfmsp2
gene and neutral microsatellite loci.
Pfdhps
and
Pfdhfr
alleles associated with sulfadoxine-pyrimethamine (SP) resistance and flanking microsatellite loci were investigated, and the prevalences of drug resistance-associated point mutations of the
Pfcrt
,
Pfmdr1
,
Pfdhfr
, and
Pfdhps
genes were estimated. Further, to monitor the use of ACT, we provide the baseline prevalences of K13 propeller mutations and
Pfmdr1
copy numbers. After 8 years, noticeable differences occurred in the distribution of genotypes conferring resistance to chloroquine and SP, and the spread of mutated genotypes differed according to the setting. Regarding artemisinin resistance, although mutations reported as being linked to artemisinin resistance were not present at the time, several single nucleotide polymorphisms (SNPs) were observed in the K13 gene, suggesting that closer monitoring should be maintained to prevent the possible spread of artemisinin resistance in Africa.
Arginase Is Essential for Survival of Leishmania donovani Promastigotes but Not Intracellular Amastigotes
Authors: Boitz Jan M. , Gilroy Caslin A. , Olenyik Tamara D. , Paradis Dustin , Perdeh Jasmine , Dearman Kristie , Davis Madison J. , Yates Phillip A. , Li Yuexin , Riscoe Michael K. , Ullman Buddy , Roberts Sigrid C. 
Published: October 2016

ABSTRACTStudies ofLeishmania donovanihave shown that both ornithine decarboxylase and spermidine synthase, two enzymes of the polyamine biosynthetic pathway, are critical for promastigote proliferation and required for maximum infection in mice. However, the importance of arginase (ARG), the first enzyme of the polyamine pathway inLeishmania, has not been analyzed inL. donovani. To test ARG function in intact parasites, we generated Δargnull mutants inL. donovaniand evaluated their ability to proliferatein vitroand trigger infections in mice. The Δargknockout was incapable of growth in the absence of polyamine supplementation, but the auxotrophic phenotype could be bypassed by addition of either millimolar concentrations of ornithine or micromolar concentrations of putrescine or by complementation with either glycosomal or cytosolic versions of ARG. Spermidine supplementation of the medium did not circumvent the polyamine auxotrophy of the Δargline. Although ARG was found to be essential for ornithine and polyamine synthesis, ornithine decarboxylase appeared to be the rate-limiting enzyme for polyamine production. Mouse infectivity studies revealed that the Δarglesion reduced parasite burdens in livers by an order of magnitude but had little impact on the numbers of parasites recovered from spleens. Thus, ARG is essential for proliferation of promastigotes but not intracellular amastigotes. Coupled with previous studies, these data support a model in whichL. donovaniamastigotes readily salvage ornithine and have some access to host spermidine pools, while host putrescine appears to be unavailable for salvage by the parasite.
A Nonsense Mutation in Mycobacterium marinum That Is Suppressible by a Novel Mechanism
Authors: Williams Emily A. , Mba Medie Felix , Bosserman Rachel E. , Johnson Benjamin K. , Reyna Cristal , Ferrell Micah J. , Champion Matthew M. , Abramovitch Robert B. , Champion Patricia A. 
Published: October 2016

ABSTRACT

Mycobacterial pathogens use the ESAT-6 system 1 (Esx-1) exporter to promote virulence. Previously, we used gene disruption and complementation to conclude that the
MMAR_0039
gene in
Mycobacterium marinum
is required to promote Esx-1 export. Here we applied molecular genetics, proteomics, and whole-genome sequencing to demonstrate that the
MMAR_0039
gene is not required for Esx-1 secretion or virulence. These findings suggest that we initially observed an indirect mechanism of genetic complementation. We identified a spontaneous nonsense mutation in a known Esx-1-associated gene which causes a loss of Esx-1 activity. We show that the Esx-1 function was restored by nonsense suppression. Moreover, we identified a polar mutation in the
ppsC
gene which reduced cellular impermeability but did not impact cytotoxicity in macrophages. Our studies reveal insight into Esx-1 export, nonsense suppression, and cell envelope lipid biogenesis.