bluuebunny/crossref_metadata_2025 huggingface dataset:
Simplified Approach to Design of Crushable Material due to Dynamic Load
Authors: Vongmongkol Sivadol , Faal-Amiri Asgar , Srivastava Hari M.
Published: October 2013

Crushable material has widely been used as an engineering solution for energy absorption devices among many industries. Abnormal and severe accident loads in the design of nuclear power plants are required to be addressed in order to comply with Nuclear Regulatory Commission (NRC) requirements which makes the crushable material more suitable in its highly dynamic application. One of the severe loads is from a postulated high energy piping system rupture. Its effects are required to be mitigated so that the proper operation of safety related systems, structures and components (SSC) of these facilities is assured. The postulated pipe rupture loads are among the highest loads that need to be addressed in the design process of nuclear power plants.

The impact forces produced by the postulated pipe rupture are typically being absorbed by energy absorption devices called “Pipe Whip Restraints” in which the restraints can minimize the loads affecting the SSCs to within an acceptable limit. This paper provides a simplified closed-form solution to determine the energy absorbing characteristic that will help to design these devices. This paper will also provide a comparison between results of the proposed simplified closed-form solution equations to the experimental test results and the calculated results using finite element analysis.
Gas-Liquid Bubbly Turbulent Upward Flow in Square Duct
Authors: Sun HaoMin , Kunugi Tomoaki , Wu DaZhuan , Zhang HongNa , Nakamura Hideo , Shen XiuZhong
Published: October 2013

As for the turbulent two-phase flow in the non-circular duct, the flow could show an anisotropic turbulence feature in liquid phase. In this study, the air-water bubbly turbulent upward flow experiment in the large square duct with the inside cross-section of 136mm×136mm has been conducted. Since the bubble size is very important for air-water bubbly flows, the bubble generating method was improved to get more uniform bubble size. After confirming the flow symmetry in the measuring cross-section, the distributions of local void fraction, bubble frequency and primary liquid velocity were measured by a hot-film anemometry, and the bubble behaviors were also investigated by using the high-speed video camera. The results show that the bubbles tend to accumulate to the wall region, where the liquid primary velocity shows the maximum especially at the corner.
Assessment of Selected Two-Phase Friction Multiplier Correlations for Steam-Water Flows in Vertical Heated and Unheated Tubes
Authors: Durmayaz A. , Odabaş I. A. , Groeneveld D. C. , Gengeç N. E.
Published: October 2013

In this study, around 10 000 experimental two-phase (2ϕ) flow pressure drop (ΔP) data for steam-water in uniformly heated and adiabatic vertical tubes have been compiled from the literature.

The compiled data have been used to assess the prediction accuracy of two-phase friction multiplier (ϕlo2) correlations selected from the literature and the homogeneous-flow model for steam-water flow in vertical tubes. The predictions of the ϕlo2 correlations have also been compared to the predictions of the homogeneous-flow model. The assessments are based on comparisons of the average and the RMS errors.

Additionally, ΔP components (due to gravitation, acceleration and friction) have been examined for a variety of flow conditions in vertical heated and unheated tubes.

The results of the assessments show that the predictions of Muller-Steinhagen and Heck (1986) correlation yield the minimum RMS error for flow in heated tubes and the predictions of the Chisholm (1973) correlation yield the minimum RMS error for flow in adiabatic tubes when these predictions are compared with both the data base and the predictions of the homogeneous-flow model.

It is concluded from the research and a review of the literature that the current state of the art is such that none of the investigated prediction methods is very good because of their large RMS errors. More work is needed to expand the ΔP data base especially for adiabatic two-phase flow. Also, a systematic experimental study should be performed on the effect of heating on the 2ϕ-flow ΔP.
Graphite Component Testing on the Load Capacity of the Dowel-Brick Structure in HTR-PM
Authors: Shi Li , Sun Libin , Wang Zonggang , Hu Yuqin , Zhang Zhensheng
Published: October 2013

Graphite core components which form the moderator and reflector structures in High Temperature Reactor Pebble bed Module (HTR-PM) are subjected to various kinds of loads. Graphite keys and dowels are designed to maintain the structure integration and dimension stability of the graphite assembly during the operation of the plant. The dowel-brick structures bear the shear loads between different layers of the graphite bricks. Experiments have been carried out to study the shear load capacity of the graphite dowel and dowel-brick structure. The load-displacement curves and the failure modes were obtained for different dowels used in HTR-PM. The results show that for a dowel-brick structure subjected to lateral load, graphite brick failed first with cracks initiated around the dowel socket. The load capacity of the dowel-brick structure is lower than that of the dowel itself. The shear stiffness of the dowel-brick structure was obtained to calculate the relative displacement of adjacent graphite bricks connected by dowels.
Post Test Analysis of ICE Tests
Authors: Tarantino Mariano , Del Nevo Alessandro , Forgione Nicola , Bandini Giacomino
Published: October 2013

Since 1999 ENEA is developing the heavy liquid metal (HLM) technology aiming to support the design and implementation of a Lead cooled Fast Reactor (LFR) and an Accelerator Driven System (ADS), both in the frame of the Italian and European research programs.

In these contexts several experiments have been performed, in different fields, going from coolant thermal-hydraulic, component development and structural material characterization.

Recently, in the frame of the IP-EUROTRANS (6th Framework Program EU), domain DEMETRA, ENEA assumed the commitment to perform an integral experiment aiming to reproduce the primary flow path of a pool-type nuclear reactor, cooled by Lead Bismuth Eutectics (LBE).

This experimental activity, named “Integral Circulation Experiment (ICE)”, has been implemented thanks a joint effort of several research institutes, mainly ENEA and University of Pisa, allowing to design an appropriate test section. This has been installed in the CIRCE facility, the largest worldwide experimental facility for the HLM technology investigation.

The goal of the experiments was to demonstrate the technological feasibility of a heavy liquid metal (HLM) pooltype nuclear system in a relevant scale (1 MW), investigating the related thermal–hydraulic behavior under both steady state and transient conditions.

This paper reports a description of the experiment, as well as the results carried out in the first experimental campaign run on the CIRCE pool, which consists of a full power steady state test, an un-protected loss of heat sink (ULOH) test, and an un-protected loss of flow (ULOF) test.

The post-test analyses of the experiments is presented. The whole domain has been modeled by a suitable 1-D nodalization, and the results carried out have been studied performing numerical calculations by the REALP5 system code modified to take in account the LBE thermal-physical properties when employed as nuclear coolant.

The obtained experimental results as well as the performed post-test analysis have demonstrated the thermal-hydraulic and technological feasibility of a pool-type nuclear system cooled by HLM.
Seismic Test and Analyses on Double-Layer Model of HTR-PM Graphite Structure
Authors: Sun Libin , Shi Li , Wang Hongtao , Wang Haitao , Hu Yuqin , Zhang Zhensheng
Published: October 2013

This research is to investigate the feasibility and practicability of carrying out an experimental work to support the seismic assessment of High Temperature Reactor Pebble bed Module (HTR-PM) reactor graphite core structure, which contains thousands of graphite bricks and tens of thousands of keys/dowels. The seismic responses of HTR-PM reactor under the seismic and impact conditions are beyond the applicability of the analytical methods currently employed, and the experimental program would be required to enhance the development of alternative analytical method and extensions of the current methods. This work can provide information and judgments for potential future work that would be nuclear safety related. The seismic excitations applied on the 1:2 double-layer graphite core model without side and top metallic components support, which is part of HTR-PM side reflector structure, included: (a) the white noise excitation from 0.1g to 0.5g amplitude in two orthogonal directions; (b) sine-sweep, frequency band from 1.0 to 35.0 back to 1.0 Hz, sweep rates less than 2 oct/min while 1 oct/min around resonant frequencies, at constant 0.5g amplitude in one horizontal uniaxial excitation; (c) five OBEs (Operating Basis Earthquake) up to 7.4g and (d) one SSE (Safe Shutdown Earthquake) up to 8.0g by considering scale law; (e) Four similar models have been tested with different gaps (1.6, 3.0 and 5.0mm) between bricks and with/without holddown plates, which can indicate approximately core structure characteristic at different lifetime for graphite irradiation deformation. The response of acceleration and displacement are measured in the tests. The natural frequencies of double layers model, bricks radial and tangential relative displacement have been calculated from the test results. Damaged graphite components have been counted and analyzed. The purpose of the test is to (a) investigate model dynamic behavior and response characteristics of integrated graphite components, (b) verify model scaling laws; (b) provide specific data on bricks relative displacement, acceleration; (c) provide data for correlation with analytical models; (d) verify the seismic analysis code to be developed in INET, and (e) optimize the detail design for HTR-PM project. The preliminary simulation results achieved good agreement with the data obtained from the test.
Estimation of Emergency Planning Zones (EPZs) for Nuclear Research Reactor Using Plume Dispersion Code
Authors: Hussain Mazzammal , Khan Salah Ud-Din , Syed Waqar A. Adil
Published: October 2013

After Fukushima nuclear power plant accident, a demand for re-evaluation of emergency planning zones for nuclear facilities has emerged to ensure that in case of nuclear accident, the population, the environment and the property should lie in the safe zone. Emergency planning zones (EPZs) around a facility are the designated areas where protective measures are adopted according to predefined emergency plan for different emergency situations.

Deterministic and probabilistic approaches have been adopted to assess and design emergency planning zones for design base accidents (DBAs), however, after Fukushima nuclear power plant accident, multi-layer failure of the plant systems could not be ruled out. To estimate the dispersion of radioactive material and respective radiation doses received by the affected people, different techniques are used including on-field measurements through survey meters, on-line monitoring network and state-of the art codes for plume dispersion modeling.

In this study plume dispersion modeling and estimation of emergency planning zones has been carried out using plume dispersion code for hypothetical accident scenarios at a 10MW nuclear research reactor. Different accident scenarios were considered with different release characteristic and environmental conditions to study the affect of the parameters including release height, heat content, release time, atmospheric stability. The simulation results have been analyzed to assess the existing emergency planning zones of nuclear research reactor.
Integrated Multi-Modular Fast Reactor Concept Design
Authors: Patel Vishal , Tsvetkov Pavel
Published: October 2013

The Integrated Multi-Modular Fast reactor is a pre-conceptual small modular fast reactor design consisting of 7 self-consist subcritical modules, each utilizing a BeO-MOX concept fuel with complete supercritical CO2 brayton cycle turbo-machinery. The subcritical modules, when brought into proximity of one another, form a complete critical reactor core. The feasibility of the reactor is assessed on a full core level, which includes a neutronics, thermal hydraulics, balance of plant, economics, and economics analysis. It has been shown that a critical configuration lasting for 14 years at 10 MWth can be achieved. A hot channel thermal hydraulics and safety analysis shows that the reactor can operate within safety limits with negative temperature coefficients of reactivity as well as stay within fuel temperature limits. A plant thermal efficiency of 36% was achieved and there is room for optimization to achieve higher efficiencies. An economical feasibility assessment shows that the reactor can be economical based on an economy of serial production argument. The analysis also leads to a licensing discussion.
Subsynchronous Resonance and Torsional Effects on a Steam Turbine Generator in Transmission Systems With Series Capacitor Compensation
Authors: Mutama K. R. , Seeliger J. , Baker D. H. , D’Aquila R. , Fitzgerald B. , Wegner C. , Staulters R. M.
Published: October 2013

Turbine-generators which connect to transmission systems with series capacitor compensated lines can experience problems with the torsional oscillations of the shaft interacting with the electrical oscillations of the series capacitors and transmission system inductance. This resonant interaction is called Subsynchronous Resonance (SSR) since it involves torsional and electrical oscillations which are below the synchronous operating frequency of the power system. The transmission lines near the Newmont TS Power Plant will soon have series capacitors installed. Modeling studies based on calculated torsional frequencies and estimated torsional damping showed that the turbine-generator could have instabilities of the torsional oscillations under some operating conditions. After the modeling studies were completed, actual tests on the steam turbine generator were conducted to measure the frequency and mechanical damping of the torsional oscillations. Field measurements validated modeling studies and showed the SSR risk may be higher than originally estimated. As a result of these investigations, a torsional stress relay is being installed to protect the unit from subsynchronous torsional effects of the series capacitors. The torsional stress relay will trip the unit if damaging torsional oscillations or torsional instabilities occur.
Scientific Bases of Corrosion Control for Water-Cooled Fusion Reactors Such as ITER
Authors: Saji Genn
Published: October 2013

Scientific bases for corrosion control for water-cooled fusion reactors, such as ITER, are discussed in this paper.

In the previous overview papers [1,2], the author has identified that ‘long cell action’ corrosion plays a pivotal role in practically all unresolved corrosion issues, irrespective of fission reactor types and operation. In trying to confirm the existence of radiation-induced ‘long-cell’ action (macro) corrosion cell in the primary cooling system of LWRs, the author attempted to theoretically reproduce the electrochemical potential differences demonstrated during experiments at the INCA Loop in Sweden and the NRI-Rez Loop in the Czech Republic [3,4].

Based on these knowledge bases, characterization of water chemistry for fusion was made through radiation- and electro-chemistry analysis following the methodology explained in the companion paper also presented at this conference [5].

Approximately 70 mV of potential difference is predicted between the high dose rate and the out-of-flux regions through the illustrative model examined in this paper, which supports the existence of the LGCA mechanism. This value is about 1/5 of the potential difference for a typical PWR. For further verification of this approach, ‘international benchmark in-pile tests’ are highly awaited. Further optimization studies as well as material testing under the influence of the LGCA mechanism should be performed to establish corrosion control.
Design and Control of Bypass Condensers
Authors: Nadig Ranga , Phipps Michael
Published: October 2013

In waste to energy plants and certain genre of cogeneration plants, it is mandatory to condense the steam from the boiler or HRSG in a separate bypass condenser when the steam turbine is out of service. The steam from the boiler or HRSG is attemperated in a pressure reducing desuperheating valve and then condensed in a bypass condenser. To avoid flashing of condensate in downstream piping it is customary to subcool the condensate in the bypass condenser. Circulating water from the steam surface condenser is used to condense the steam in the bypass condenser.

Some of the challenges involved in the design of the bypass condenser are:

• High shellside design pressure and temperature

• Condensate subcooling

• Large circulating water (tubeside) flow rate

• Relatively low circulating water (tubeside) inlet temperature

• Large Log Mean Temperature Difference (LMTD)

• Large shell diameters

• Small tube lengths

The diverse requirements complicate the mechanical and thermal design of the bypass condenser. This paper highlights the complexities in the design and performance of the bypass condenser. Similarities with the design and operation of steam surface condensers and feedwater heater are reviewed. The uniqueness of the bypass condenser’s design and operation are discussed and appropriate solutions to ensure proper performance are suggested.
A Concept of Classification Criteria of External Hazards for PRA of Nuclear Power Plants
Authors: Narumiya Yoshiyuki , Kuramoto Takahiro
Published: October 2013

The safety of NPPs has to be maintained in any condition which has to be considered. Rational criteria are especially needed for adequate classification of external hazards. Characteristics of external hazards, e.g. Tsunami, Earthquake, Land slide etc, are changed by features of the site. It is necessary to make a rational and clear process of classification to appropriate method of risk assessment. This study treated of various external hazards included natural phenomena and man-made events. Much disaster information was gathered from historical documents these one thousand and five hundred years (1). Published standards of US and IAEA were referred. This study provided some viewpoints for classification, e.g. hazard frequency, range of impact, basic design, and difficulty of accident management etc. The classification included several paths; a full-scope PRA, a hazard analysis, or a comparison between an impact of the hazard and the design condition against it.
Flow Characterization and Heat Transfer of Core-Catcher in Passive Safety System
Authors: Kurita Tomohisa , Tobimatsu Toshimi , Tahara Mika , Yamada Masato , Kojima Yoshihiro
Published: October 2013

A mitigation system which can keep core melt stable after a severe accident is necessary to a next generation BWR design. Toshiba has been developing a compact core catcher to be placed at the lower drywell in the containment vessel. The cooling water for the core catcher is supplied from the passive flooder and PCCS drain line. After the core catcher is flooded, the molten core would be cooled by both overflooding water and inclined cooling channels, in which water is boiling and natural circulation is established. So the core catcher can operate in passive manner and has no active component inside the containment.

This paper summarizes flow dynamics and heat removal capability in an inclined cooling channel of core catcher when cooling water flows by the natural circulation.
Analytical Prediction of Turbulent Friction Factor in Circular Pipe Under Supercritical Conditions
Authors: Zang Jinguang , Yan Xiao , Huang Shanfang , Xiao Zejun , Huang Yanping
Published: October 2013

An analytical method was proposed for the prediction of the turbulent friction factor in a circular pipe under supercritical conditions. The friction factor equation was based on the new wall function by Van Direst transformation which is widely used in compressed flow. The law of the wall of two layers was used and integrated over the entire flow area to obtain the algebraic form of the turbulent friction factor. The new turbulent friction formula was first adjusted to Colebrook equation in isothermal flow at supercritical pressures. And then it was validated in heated supercritical flow by several existing correlations. Similar trends were found between them, which confirms the physical validity of the new frictional formula. The theoretical analysis also shows that the friction factor due to the variation of fluid property at supercritical pressures is mainly caused by the density and viscosity variation. In viscous sublayer, both the viscosity play the main role, while in turbulent sublayer, only the density do.
Hydrogen Detonation in a Flat Semi-Confined Layer
Authors: Kuznetsov M. , Grune J. , Jordan T. , Rudy W. , Teodorczyk A.
Published: October 2013

Hydrogen accumulation at the top of the containment or reactor building may occur due to an interaction of molten corium and water followed by a severe accident of a nuclear reactor (TMI, Chernobyl, Fukushima Dai-ichi). Hydrogen accumulates usually in a containment of nuclear reactor as a stratified semi-confined layer of hydrogen-air mixture. Detonation of such mixture may lead to significant damage of the containment structure. A series of large scale experiments on hydrogen combustion and detonation in a semi-confined layer of uniform and non-uniform hydrogen-air mixtures in presence of obstructions or without them was performed at the Karlsruhe Institute of Technology (KIT). Critical conditions for deflagration-to-detonation transition and then for steady state detonation propagation were experimentally evaluated in a flat semi-confined layer. The experiments were performed in a horizontal semi-confined layer with dimensions of 9×3×0.6 m with/without obstacles opened from below. The hydrogen concentration in the mixtures with air was varied in the range of 0–34 vol.% without or with a gradient of 0–1.1 mol. %H2/cm. Effects of hydrogen concentration gradient, thickness of the layer, geometry of the obstructions, average and maximum hydrogen concentration on critical conditions for detonation onset and then propagation were investigated with respect to the safety analysis. Blast wave strength and mechanical response of the safety volume was experimentally measured as well.
Experimental and Analysis Study of Free Standing Rack Under Seismic Excitation
Authors: Taniguchi Katsuhiko , Okuno Daisaku , Iwasaki Akihisa , Nekomoto Yoshitsugu , Matsuoka Toshihiro
Published: October 2013

For high earthquake resistance and ease of installation, free standing racks which are not anchored to the pool floor or walls has been adopted in many countries.

Under the earthquake, the response of the free standing rack is highly nonlinear and involves a complex combination of motions (sliding, rocking, twisting, and turning) and impacts between the fuel assemblies and the fuel cell walls, rack-to-rack, and the pit floor and rack pedestals. To obtain an accurate simulation of the free standing rack, the seismic analysis requires careful considerations of these complex phenomena (sliding, rocking, twisting, and turning), fluid coupling effects and frictional effects.

We carried out seismic experiments on the full-scale rack model in water and dry conditions to obtain the fundamental data about free standing rack (sliding, rocking and turning motions). We have developed the nonlinear dynamic analysis method to predict seismic response for the free standing rack utilizing the full-scale test result and verified the analysis evaluation method of the rack by comparison of test result.
On the Inflow Phenomenon in Near Field of Buoyant Jet at Low Froude Number
Authors: Maeda Atsushi , Yamagata Takayuki , Fujisawa Nobuyuki
Published: October 2013

In the present paper, the inflow phenomenon in the near-field of a buoyant jet issuing from a square duct is studied by using scanning LIF and scanning PIV measurements. The scanning LIF visualization allows an insight into the critical condition of the inflow phenomenon in a wide range of Froude number and Reynolds number. While, the scanning PIV allows the quantitative information on the inflow rate through the duct exit. The experimental result shows that the critical Froude number increases with an increase in Reynolds number in the duct exit up to Reynolds number 2,000, though it is weakened at higher Reynolds number. The examination of the inflow rate indicates that the large magnitude of the inflow rate occurs in the lower Froude number and Reynolds number.
Analysis for Low Pressure Cooling Injection System Suction Hydrodynamics for a Boiling Water Reactor
Authors: Ozar Basar , Harvill Rodney , Henry Christopher E. , Norton Deborah A.
Published: October 2013

A study to characterize the steam waterhammer phenomena of a low pressure cooling injection (LPCI) system for a Mark 1 boiling water reactor (BWR) has been performed using RELAP5 and GOTHIC during a transient event. The scenario of particular interest was a manual switchover from shutdown cooling mode 3 to low pressure injection due to a loss of coolant accident (LOCA). This transient was initiated by opening the isolation valves of the two trains on a LPCI system into the torus. The torus was considered to be at atmospheric pressure and 20°C. The initial condition of the problem was set up such that the liquid was stagnant in the system. The initial temperature and pressure of the liquid, which was between the torus and isolation valves, was considered to be the same as the torus conditions. On the other hand, the initial condition of the liquid upstream of the isolation valves was chosen to be at 1 MPa and near saturation temperature. The analysis showed that the liquid in the system flashed into steam and discharged into the torus after the isolation valves started to open. Discharge of steam continued until the pressure in the LPCI system reached to a hydrostatic equilibrium with the torus. Following this, the cold liquid from the torus began to reflod the LPCI piping while condensing the steam at the liquid-steam interphase. This caused a mild steam waterhammer event when all of the steam condensed in the piping segments with closed ends. A sensitivity analysis showed that, the magnitude of the steam waterhammer predicted by both codes was sensitive to the number of nodes selected to model the piping, where the steam waterhammer phenomena occurred. Technical basis was obtained from the available literature and used as a guide to choose the number of nodes for the models in both codes. Once the steam waterhammer and the hydrodynamic properties associated with this transient were predicted by both codes, the forces exerted on critical pipe components were calculated. Also, selected thermal-hydraulic properties and hydrodynamic loads were compared between both code calculations. Comparisons showed reasonable agreements.
Investigation of Effects of Piping Configuration and Water Supply Pressure on Air Intrusion
Authors: Lim Jaehyok , Ozar Basar , Henry Christopher E. , Ramsden Kevin B.
Published: October 2013

An evaluation of the effects of geometry and water supply pressure on the void transport has been performed using RELAP5/MOD3.3 (patch03). Two different piping configurations were considered for a hypothetical nuclear power plant. The cases that were analyzed considered switchover between two different water supplies, i.e. condensate storage tank (CST) and essential service water system (SX) for a safety system that acted as the ultimate heat sink. In addition, two different pressures were considered for the pressure of SX to investigate the effect of supply water pressure on void transport. Results were interpreted based on the differences in the geometries of the piping configurations and supply water pressures.
Is ExacTrac x‐ray system an alternative to CBCT for positioning patients with head and neck cancers?
Authors: Clemente Stefania , Chiumento Costanza , Fiorentino Alba , Simeon Vittorio , Cozzolino Mariella , Oliviero Caterina , Califano Giorgia , Caivano Rocchina , Fusco Vincenzo
Published: October 2013

Purpose:

To evaluate the usefulness of a six‐degrees‐of freedom (6D) correction using ExacTrac robotics system in patients with head‐and‐neck (HN) cancer receiving radiation therapy.

Methods:

Local setup accuracy was analyzed for 12 patients undergoing intensity‐modulated radiation therapy (IMRT). Patient position was imaged daily upon two different protocols, cone‐beam computed tomography (CBCT), and ExacTrac (ET) images correction. Setup data from either approach were compared in terms of both residual errors after correction and punctual displacement of selected regions of interest (Mandible, C2, and C6 vertebral bodies).

Results:

On average, both protocols achieved reasonably low residual errors after initial correction. The observed differences in shift vectors between the two protocols showed that CBCT tends to weight more C2 and C6 at the expense of the mandible, while ET tends to average more differences among the different ROIs.

Conclusions:

CBCT, even without 6D correction capabilities, seems preferable to ET for better consistent alignment and the capability to see soft tissues. Therefore, in our experience, CBCT represents a benchmark for positioning head and neck cancer patients.
Bactofencin A, a New Type of Cationic Bacteriocin with Unusual Immunity
Authors: O'Shea Eileen F. , O'Connor Paula M. , O'Sullivan Orla , Cotter Paul D. , Ross R. Paul , Hill Colin
Published: October 2013

Bacteriocin production is an important probiotic trait of intestinal bacteria. In this study, we identify a new type of bacteriocin, bactofencin A, produced by a porcine intestinal isolate
Lactobacillus salivarius
DPC6502, and assess its potency against pathogenic species including
Staphylococcus aureus
and
Listeria monocytogenes
. Genome sequencing of the bacteriocin producer revealed
bfnA
, which encodes the mature and highly basic (pI 10.59), 22-amino-acid defensin-like peptide. Matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectral analysis determined that bactofencin A has a molecular mass of 2,782 Da and contains two cysteine residues that form an intramolecular disulfide bond. Although an ABC transporter and transport accessory protein were also present within the bacteriocin gene cluster, a classical bacteriocin immunity gene was not detected. Interestingly, a
dltB
homologue was identified downstream of
bfnA
. DltB is usually encoded within the
dlt
operon of many Gram-positive bacteria. It is responsible for
d
-alanylation of teichoic acids in the cell wall and has previously been associated with bacterial resistance to cationic antimicrobial peptides. Heterologous expression of this gene conferred bactofencin A-specific immunity on sensitive strains of
L. salivarius
and
S. aureus
(although not
L. monocytogenes
), establishing its role in bacteriocin immunity. An analysis of the distribution of
bfnA
revealed that it was present in four additional isolates derived from porcine origin and absent from five human isolates, suggesting that its distribution is host specific. Given its novelty, we anticipate that bactofencin A represents the prototype of a new class of bacteriocins characterized as being cationic, with a DltB homologue providing a cognate immunity function.

IMPORTANCE
This study describes the identification, purification, and characterization of bactofencin A, a novel type of bacteriocin produced by
L. salivarius
DPC6502. Interestingly, bactofencin A is not similar to any other known bacteriocin but instead shares similarity with eukaryotic cationic antimicrobial peptides, and here, we demonstrate that it inhibits two medically significant pathogens. Genome sequence analysis of the producing strain also revealed the presence of an atypical
dltB
homologue in the bacteriocin gene cluster, which was lacking a classical bacteriocin immunity gene. Furthermore, cloning this gene rendered sensitive strains resistant to the bacteriocin, thereby establishing its role in providing cognate bacteriocin immunity. Four additional
L. salivarius
isolates, also of porcine origin, were found to contain the bacteriocin biosynthesis genes and successfully produced bactofencin A, while these genes were absent from five human-derived strains investigated.
Vitamin D status in recently arrived immigrants from Africa and Asia: a cross-sectional study from Norway of children, adolescents and adults
Authors: Eggemoen Åse R , Knutsen Kirsten V , Dalen Ingvild , Jenum Anne K
Published: October 2013

Objectives

To estimate the prevalence of vitamin D deficiency (25(OH)D) <50 nmol/L among recently arrived immigrants from Africa and Asia in Oslo, and to explore 25(OH)D levels according to origin, gender and age.

Design

A cross-sectional study.

Setting

Primary healthcare unit in Oslo, Norway, offering family immigrants, asylum seekers, United Nations (UN) refugees or individuals granted asylum a free medical examination on arrival.

Participants

All individuals from African and Asian countries (n=591) referred to the Centre of Migrant Health, Health Agency, Oslo, Norway in 2010, estimated to cover 60% of the targeted population.

Results

25(OH)D <50 nmol/L was very prevalent in immigrants from the Middle East (81% (95% CI 75.4% to 86.6%)), South Sahara Africa (73% (CI 67.5% to 78.5%)) and South Asia (75% (CI 64.0% to 86.0%)), in contrast to East Asians (24% (CI 12.6% to 35.4%)), p<0.001 for differences. The prevalence of 25(OH)D<25 nmol/L was lower but followed the same pattern (Middle East: 38% (CI 31.1% to 45.0%), South Sahara Africa: 24% (CI 18.7% to 29.3%) and South Asia: 35% (CI 22.9% to 47.1%), although it was not observed in East Asians (p<0.001 for differences)). The ethnic differences persisted after adjusting for the duration of residence, seasonality and residence status in multiple linear regression analyses. Female adolescents from South Asia, the Middle East and South Sahara Africa had the lowest levels of 25(OH)D. Further, country-specific median levels of 25(OH)D were low (24–38 nmol/L) among groups from Somalia, Eritrea, Afghanistan and Iraq, the countries with the largest number of immigrants in our study.

Conclusions

The majority of recently settled immigrant groups from the Middle East, South Asia and Africa had 25(OH)D <50 nmol/L, in contrast to East Asians. Female adolescents from these regions had the lowest levels of 25(OH)D.
Reducing inpatient heritable thrombophilia testing using a clinical decision-making tool
Authors: Smith Tyler W , Pi David , Hudoba Monika , Lee Agnes Y Y
Published: October 2013

Aims

To evaluate the impact of a clinical decision-making tool, designed to educate physicians regarding heritable thrombophilia (HT) testing, on the volume of testing in hospitalised patients in the tertiary care setting.

Methods

We performed a retrospective cohort study over a 6-year period (2007–2012) at a single tertiary care centre intervention site and two regional control sites. In January 2010, the intervention site instituted a policy change whereby physicians ordering HT testing on inpatients needed to complete a pre-preprinted order (PPO) form that outlined the limitations of HT testing in the hospitalised setting. Failure to complete the PPO within 24 h resulted in test cancellation. Our main outcome measure was the volume of HT testing performed at the three study sites.

Results

Introduction of the PPO resulted in a 79.4% (95% CI 71.2% to 87.6%) reduction in factor V Leiden (FVL) testing at the intervention site. This decrease was significantly greater compared with those in the two control teaching hospitals over the same time periods (33.7% and 43.6%; both p<0.001). Reductions in FVL testing postintervention were observed among all ordering specialists. Similar postintervention reductions in testing volumes were observed for antithrombin (57.4%), protein C (61.9%) and protein S (62.2%) activity assays.

Conclusions

In a large tertiary care hospital, the introduction of a clinical decision-making tool significantly reduced HT testing in inpatients across clinical specialties. The impact on patient outcome should be assessed in further studies.
The value of archival tissue blocks in understanding breast cancer biology
Authors: Dowsett Thomas , Verghese Eldo , Pollock Steven , Pollard Jennifer , Heads Judith , Hanby Andrew , Speirs Valerie
Published: October 2013

Pathological reporting of breast cancer has evolved alongside scientific advances. Such advances have led to recognition of different molecular classes of breast cancer resulting in improved disease management. The aim of this study was to establish whether these advances could be applied to archival breast cancer cases dating from the 1940s to assess historical trends. Important observations included the marked differences in pathological reporting, size of tumour and in ERα expression throughout the decades.
REVIEW OF RECENT RESULTS FROM THE RHIC BEAM ENERGY SCAN
Authors: KUMAR LOKESH
Published: October 2013

We review recent results from the RHIC beam energy scan (BES) program, aimed to study the Quantum Chromodynamics (QCD) phase diagram. The main goals are to search for the possible phase boundary, softening of equation of state or first order phase transition, and possible critical point. Phase-I of the BES program has recently concluded with data collection for Au+Au collisions at center-of-mass energies [Formula: see text] of 7.7, 11.5, 19.6, 27 and 39 GeV. Several interesting results are observed for these lower energies where the net-baryon density is high at the mid-rapidity. These results indicate that the matter formed at lower energies (7.7 and 11.5 GeV) is hadron dominated and might not have undergone a phase transition. In addition, a centrality dependence of freeze-out parameters is observed for the first time at lower energies, slope of directed flow for (net)-protons measured versus rapidity shows an interesting behavior at lower energies, and higher moments of net-proton show deviation from Skellam expectations at lower energies. An outlook for the future BES Phase-II program is presented and efforts for the detailed study of QCD phase diagram are discussed.
A NONASSOCIATIVE QUATERNION SCALAR FIELD THEORY
Authors: GIARDINO SERGIO , TEOTÔNIO-SOBRINHO PAULO
Published: October 2013

A nonassociative Groenewold–Moyal (GM) plane is constructed using quaternion-valued function algebras. The symmetrized multiparticle states, the scalar product, the annihilation/creation algebra and the formulation in terms of a Hopf algebra are also developed. Nonassociative quantum algebras in terms of position and momentum operators are given as the simplest examples of a framework whose applications may involve string theory and nonlinear quantum field theory.
ON THE PROBLEM OF VACUUM ENERGY IN FLRW UNIVERSES AND DARK ENERGY
Authors: YDRI BADIS , BOUCHAREB ADEL
Published: October 2013

We present a (hopefully) novel calculation of the vacuum energy in expanding FLRW spacetimes based on the renormalization of quantum field theory in nonzero backgrounds. We compute the renormalized effective action up to the two-point function and then apply the formalism to the cosmological backgrounds of interest. As an example we calculate for quasi de Sitter spacetimes the leading correction to the vacuum energy given by the tadpole diagram and show that it behaves as [Formula: see text] where H0 is the Hubble constant and Λ P is the Planck constant. This is of the same order of magnitude as the observed dark energy density in the universe.
PHOTOLUMINESCENCE SPECTRA AND MAGNETIC PROPERTIES OF HYDROTHERMALLY SYNTHESIZED MnO2 NANORODS
Authors: TOUFIQ ARBAB MOHAMMAD , WANG FENGPING , JAVED QURAT-UL-AIN , LI QUANSHUI , LI YAN
Published: October 2013

In this paper, single crystalline tetragonal MnO 2 nanorods have been synthesized by a simple hydrothermal method using MnSO 4⋅ H 2 O and Na 2 S 2 O 8 as precursors. The crystalline phase, morphology, particle sizes and component of the as-prepared nanomaterial were characterized by employing X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and energy-dispersive X-ray spectroscopy (EDS). The photoluminescence (PL) emission spectrum of MnO 2 nanorods at room temperature exhibited a strong ultraviolet (UV) emission band at 380 nm, a prominent blue emission peak at 453 nm as well as a weak defect related green emission at 553 nm. Magnetization (M) as a function of applied magnetic field (H) curve showed that MnO 2 nanowires exhibited a superparamagnetic behavior at room temperature which shows the promise of synthesized MnO 2 nanorods for applications in ferrofluids and the contrast agents for magnetic resonance imaging. The magnetization versus temperature curve of the as-obtained MnO 2 nanorods shows that the Néel transition temperature is 94 K.
A FOUR-PHASES METHODOLOGY TO PROPOSE ANTI-PORNOGRAPHY SYSTEM BASED ON NEURAL AND BAYESIAN METHODS OF ARTIFICIAL INTELLIGENCE
Authors: ZAIDAN A. A. , ABDUL KARIM H. , AHMAD N. N. , ZAIDAN B. B. , SALI A.
Published: October 2013

Pornographic images are disturbing and malicious contents that are easily available through Internet technology. It has a negative and lasting effect on children who use the Internet; thus, pornography has become a serious threat not only to Internet users but also to society at large. Therefore, developing efficient and reliable tools to automatically filter pornographic contents is imperative. However, the effective interception of pornography remains a challenging issue. In this paper, a four-phase anti-pornography system based on the neural and Bayesian methods of artificial intelligence is proposed. Primitive information on pornography is examined and then used to determine if a given image falls under the pornography category. First, we present a detailed description of preliminary study phase followed by the modeling phase for the proposed skin detector. An anti-pornography system is created in the development phase, which also includes the proposed pornography classifier based on skin detection. Finally, the performance assessment method for the proposed anti-pornography system is discussed in the evaluation phase.
PERIODICALLY FORCED PIECEWISE-LINEAR ADAPTIVE EXPONENTIAL INTEGRATE-AND-FIRE NEURON
Authors: SHIAU LIEJUNE , LAING CARLO R.
Published: October 2013

Although variability is a ubiquitous characteristic of the nervous system, under appropriate conditions neurons can generate precisely timed action potentials. Thus considerable attention has been given to the study of a neuron's output in relation to its stimulus. In this study, we consider an increasingly popular spiking neuron model, the adaptive exponential integrate-and-fire neuron. For analytical tractability, we consider its piecewise-linear variant in order to understand the responses of such neurons to periodic stimuli. There exist regions in parameter space in which the neuron is mode locked to the periodic stimulus, and instabilities of the mode locked states lead to an Arnol'd tongue structure in parameter space. We analyze mode locked solutions and examine the bifurcations that define the boundaries of the tongue structures. The theoretical analysis is in excellent agreement with numerical simulations, and this study can be used to further understand the functional features related to responses of such a model neuron to biologically realistic inputs.
BIFURCATION OF LIMIT CYCLES AND ISOCHRONOUS CENTERS FOR A QUARTIC SYSTEM
Authors: HUANG WENTAO , CHEN AIYONG , XU QIUJIN
Published: October 2013

For a quartic polynomial system we investigate bifurcations of limit cycles and obtain conditions for the origin to be a center. Computing the singular point values we find also the conditions for the origin to be the eighth order fine focus. It is proven that the system can have eight small amplitude limit cycles in a neighborhood of the origin. To the best of our knowledge, this is the first example of a quartic system with eight limit cycles bifurcated from a fine focus. We also give the sufficient and necessary conditions for the origin to be an isochronous center.
STOCHASTIC INTEGRATION WITH RESPECT TO THE CYLINDRICAL WIENER PROCESS VIA REGULARIZATION
Authors: OLIVERA CHRISTIAN
Published: October 2013

Following the ideas of F. Russo and P. Vallois, we use the notion of forward integral to introduce a new stochastic integral respect to the cylindrical Wiener process. This integral is an extension of the classical integral. As an application, we prove existence of solution of a parabolic stochastic differential partial equation with anticipating stochastic initial date.
EXPERIMENTAL VALIDATION OF A MEAN FILED MODEL OF MINERALIZED COLLAGEN FIBER ARRAYS AT TWO LEVELS OF HIERARCHY
Authors: SPIESZ EWA M. , REISINGER ANDREAS G. , ROSCHGER PAUL , ZYSSET PHILIPPE K.
Published: October 2013

In the course of this study, stiffness of a fibril array of mineralized collagen fibrils modeled with a mean field method was validated experimentally at site-matched two levels of tissue hierarchy using mineralized turkey leg tendons (MTLT). The applied modeling approaches allowed to model the properties of this unidirectional tissue from nanoscale (mineralized collagen fibrils) to macroscale (mineralized tendon).

At the microlevel, the indentation moduli obtained with a mean field homogenization scheme were compared to the experimental ones obtained with microindentation. At the macrolevel, the macroscopic stiffness predicted with micro finite element (μFE) models was compared to the experimental stiffness measured with uniaxial tensile tests. Elastic properties of the elements in μFE models were injected from the mean field model or two-directional microindentations.

Quantitatively, the indentation moduli can be properly predicted with the mean-field models. Local stiffness trends within specific tissue morphologies are very weak, suggesting additional factors responsible for the stiffness variations. At macrolevel, the μFE models underestimate the macroscopic stiffness, as compared to tensile tests, but the correlations are strong.
A Binary Option Pricing Based on Fuzziness
Authors: Miyake Masatoshi , Inoue Hiroshi , Shi Jianming , Shimokawa Tetsuya
Published: October 2013

In pricing for European option Black–Scholes model has been widely used in various fields in which the model can be applied under appropriate conditions. In this paper, we discuss a binary option, which is popular in OTC (Over the Counter) market for hedging and speculation. In particular, asset-or-nothing option is basic for any other options but gives essential implications for constructing more complex option products. In addition to the primary role of the asset-or-nothing option, another availability of the option is considered by introducing fuzzy concept. Therefore, the uncertainty which an investor and intermediary usually have in their minds is incorporated in the pricing model. Thus, the model is described with fuzzy boundary conditions and applied to the conventional binary option, proposing more useful and actual pricing way of the option. This methodology with the analysis is examined, comparing with Monte Carlo simulations.