bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduction of disulfide bonds within anti‐D results in enhanced Fcγ receptor blockade
Authors: Kruspe Andrew S. , Katsman Yulia , Sakac Darinka , Chagneau Cécile , Glistvain Anna , Langler Richard F. , Branch Donald R.
Published: January 2009

BACKGROUND: We have investigated whether chemicals known to disrupt disulfide bonds are capable of altering immunoglobulin anti‐D structure resulting in an increased efficacy of the chemically modified anti‐D to inhibit Fcγ receptor (FcγR)‐mediated phagocytosis. If successful, this would provide a rationale to explore this mechanism of enhancing FcγR blockade for future use in immunoglobulin therapies for immune cytopenias.

STUDY DESIGN AND METHODS: Anti‐D that was shown to block 50 percent of the FcγR‐mediated phagocytosis of opsonized red blood cells (RBCs) using a monocyte monolayer assay (MMA) was combined with two different thiol‐containing compounds, dithiothreitol (DTT) or p‐toluenesulfonylmethyl mercaptan, with or without treatment with iodoacetamide, and allowed to react. Excess chemical was removed by extensive dialysis. FcγR blockade was assessed by MMA with dialyzed, untreated, or chemically treated anti‐D using both D+ and D− opsonized target RBCs. Toxicity was determined by fluorescence‐activated cell sorting. Aggregates and oligomerization of chemically treated anti‐D were examined using gel filtration–high pressure liquid chromatography.

RESULTS: Using disulfide‐reducing compounds to chemically modify anti‐D significantly increases the efficacy of the anti‐D to induce an FcγR blockade and decrease phagocytosis in vitro of opsonized D+ or D− RBCs. This effect was shown not due to unbound residual chemical, toxicity, or formation of immunoglobulin G oligomers. S‐alkylation was required when using low concentrations of reducing compound.

CONCLUSION: Our results demonstrate that irreversible reduction of interchain disulfide bonds within the immunoglobulin anti‐D results in a significantly increased efficacy to inhibit FcγR‐mediated phagocytosis regardless of opsonized target cell. With the use of this strategy, more effective and less expensive immunoglobulin treatment for immune cytopenias such as immune thrombocytopenic purpura or autoimmune hemolytic anemia may be developed.
Effects of Etiological Agent and Bather Shedding of Pathogens on Interpretation of Epidemiological Data Used to Establish Recreational Water Quality Standards
Authors: Loge Frank J. , Lambertini Elisabetta , Borchardt Mark A. , Başağaoğlu Hakan , Ginn Timothy R.
Published: January 2009

The overall goal of the study reported herein was to use techniques in the field of risk assessment (specifically a state‐space population dynamic model of disease transmission within recreational waters) to explore the relative significance of (1) active shedding of microorganisms from bathers themselves, and (2) the type and concentration of etiological agent on the observed heterogeneity of the incidence of illness in epidemiological studies that have been used to develop ambient water quality criteria. The etiological agent and corresponding dose ingested during recreational contact was found to significantly impact the observed incidence of illness in an epidemiological study conducted in recreational water. In addition, the observed incidence of illness was found not to necessarily reflect background concentrations of indicator organisms, but rather microorganisms shed during recreational contact. Future revisions to ambient water quality criteria should address the etiological agent, dose, and the significance of microbial shedding relative to background concentrations of pathogens and indicator organisms in addition to the incidence of illness and concentration of indicator organisms. Without a quantitative assessment of these additional variables, study findings may potentially be site specific and not representative of the health risks associated with specific indicator concentrations in all recreational waters.
Mechanism of Texture Development in Bi0.5(Na,K)0.5TiO3 prepared by the Templated Grain Growth Process
Authors: Shoji Takeshi , Fuse Kaori , Kimura Toshio
Published: January 2009

The mechanisms of texture evolution in Bi0.5(Na,K)0.5TiO3 (BNKT) prepared by the templated grain growth method are examined using platelike SrBi4Ti4O15 and Al2O3 powders and SrTiO3 and Al2O3 single crystals as templates. These templates give rise to a 〈100〉 texture in the BNKT matrix. The mechanism of texture evolution is dependent on the template species. When SrBi4Ti4O15 and SrTiO3 are used, a new grain (terrace) forms between the matrix and the template grains. The terrace has the same crystallographic orientation as the template. The terrace grows at the expense of the matrix grains, resulting in texture evolution. For the Al2O3 template, no terrace forms between the matrix and the template grains. Instead, the matrix grains directly attach to the template surface. The formation of a phase boundary with a specific orientation gives rise to texture evolution for this template.
Lost Mold‐Rapid Infiltration Forming of Mesoscale Ceramics: Part 2, Geometry and Strength Improvements
Authors: Antolino Nicholas E. , Hayes Gregory , Kirkpatrick Rebecca , Muhlstein Christopher L. , Frecker Mary I. , Mockensturm Eric M. , Adair James H.
Published: January 2009

Iterative process improvements have been used to eliminate strength‐limiting geometric flaws in mesoscale bend bars composed of yttria‐tetragonal zirconia polycrystals (Y‐TZP). These improvements led to large quantities of high bend strength material. The metrology of Y‐TZP mesoscale bend bars produced using a novel lost mold‐rapid infiltration‐forming process (LM‐RIF) is characterized over several process improvements. These improvements eliminate trapezoidal cross sections in the parts, reduce concave upper surfaces in cross section, and minimize warping along the long axis of 332 × 26 × 17 μm mesoscale bend bars. The trapezoidal cross sections of earlier, first‐generation parts were due to the absorption of high‐energy ultraviolet (UV) light during the photolithographic mold‐forming process, which produced nonvertical mold walls that the parts mirrored. The concave upper surfaces in cross section were eliminated by implementing a RIF‐buffing process. Warping during sintering was attributed to impurities in the substrate, which creates localized grain growth and warping as the tetragonal phase becomes destabilized. Precision in the part dimensions is demonstrated using optical profilometry on bend bars and a triangular test component. The bend bar dimensions have a 95% confidence interval of <±1 μm, and the tip radius of the triangular test component is 3 μm, consistent with the UV‐photolithographic process used to form the mold cavities. The average bend strength of the mesoscale Y‐TZP bend exceeds 2 GPa with a Weibull modulus equal to 6.3.
A cross‐sectional investigation of discontinuation of self‐injury and normalizing pain perception in patients with borderline personality disorder
Authors: Ludäscher P. , Greffrath W. , Schmahl C. , Kleindienst N. , Kraus A. , Baumgärtner U. , Magerl W. , Treede R.‐D. , Bohus M.
Published: January 2009

Objective:  Several studies have shown reduced pain perception in patients with borderline personality disorder (BPD) and current self‐injurious behavior (SIB). The aim of the present study was to test whether pain perception in patients with current SIB is different from that of patients who had stopped SIB, and whether pain perception of the latter group differs from healthy controls (HC).

Method:  We investigated 24 borderline patients and 24 HC. Thirteen patients showed current SIB (BPD‐SIB) and 11 patients did not exhibit SIB anymore (BPD‐non‐SIB). Pain thresholds were assessed using thermal stimuli and laser radiant heat pulses.

Results:  We found significant linear trends for all pain measures. The BPD‐SIB group was less sensitive than the BPD‐non‐SIB group and the latter were less sensitive than HC. The pain sensitivity negatively correlated with borderline symptom severity.

Conclusion:  The results suggest an association between the termination of SIB, decline of psychopathology and normalization of pain perception in borderline patients.
Milia complicating bullous polymorphic light eruption
Authors: Bulai Livideanu Cristina , Ammoury Alfred , Viraben Roland , Lamant Laurence , Journée Fabienne , Paul Carle , Marguery Marie Claude
Published: January 2009

Polymorphic light eruption (PLE) is the most common photosensitivity disorder. Typically, PLE manifests in the spring or summer months as a recurrent pruritic papular and/or vesicular eruption occurring on photoexposed skin areas following sun exposure. The milia are caused by proliferative tendencies of the epithelium after injury. These may occur in areas of subepidermal bullous eruption. We report an original case of bullous PLE complicated by milia. Such association has not been reported previously.
Effects of zinc supplementation on parent and teacher behaviour rating scores in low socioeconomic level Turkish primary school children
Authors: Üçkardeş Yasemin , Özmert Elif N , Ünal Fatih , Yurdakök Kadriye
Published: January 2009

Objective: To determine the effect of zinc supplementation on behaviour in low‐income school aged children.

Design: Double‐blind randomized, placebo controlled trial.

Setting: Low‐income district primary school in Turkey.

Participants: Third grade students in the school. Among 252 students, 226 participated and 218 completed the study.

Intervention: Children in each class were randomized either to the study group to receive 15 mg/day elemental zinc syrup or to placebo group to receive the syrup without zinc for 10 weeks.

Main Outcome Measures: The change in Conner's Rating Scales for Teachers and Parents scores after supplementation.

Results: The mean Conner's Rating Scale for Parents scores on attention deficit, hyperactivity, oppositional behaviour and conduct disorder decreased significantly in the study and placebo groups after supplementation (p < 0.01). The prevalence of children with clinically significant parent ratings on attention deficit (p = 0.01) and hyperactivity (p = 0.004) decreased in the study group while prevalence of oppositional behaviour (p = 0.007) decreased in the placebo group. In children of mothers with low education all mean Parents' scores decreased significantly (p < 0.01) in the study group while only hyperactivity scores decreased in the placebo group (p < 0.01). In this subgroup the prevalence of children with clinically significant scores for attention deficit, hyperactivity and oppositional behaviour decreased only in the study group (p < 0.05). There was no change in mean Teachers' scores.

Conclusion: In our study zinc supplementation decreased the prevalence of children with clinically significant scores for attention deficit and hyperactivity. The affect on behaviour was more evident in the children of low educated mothers.
Crystal structure of the parasite inhibitor chagasin in complex with papain allows identification of structural requirements for broad reactivity and specificity determinants for target proteases
Authors: Redzynia Izabela , Ljunggren Anna , Bujacz Anna , Abrahamson Magnus , Jaskolski Mariusz , Bujacz Grzegorz
Published: January 2009

A complex of chagasin, a protein inhibitor from Trypanosoma cruzi, and papain, a classic family C1 cysteine protease, has been crystallized. Kinetic studies revealed that inactivation of papain by chagasin is very fast (kon = 1.5 × 106 m−1·s−1), and results in the formation of a very tight, reversible complex (Ki = 36 pm), with similar or better rate and equilibrium constants than those for cathepsins L and B. The high‐resolution crystal structure shows an inhibitory wedge comprising three loops, which forms a number of contacts responsible for the high‐affinity binding. Comparison with the structure of papain in complex with human cystatin B reveals that, despite entirely different folding, the two inhibitors utilize very similar atomic interactions, leading to essentially identical affinities for the enzyme. Comparisons of the chagasin–papain complex with high‐resolution structures of chagasin in complexes with cathepsin L, cathepsin B and falcipain allowed the creation of a consensus map of the structural features that are important for efficient inhibition of papain‐like enzymes. The comparisons also revealed a number of unique interactions that can be used to design enzyme‐specific inhibitors. As papain exhibits high structural similarity to the catalytic domain of the T. cruzi enzyme cruzipain, the present chagasin–papain complex provides a reliable model of chagasin–cruzipain interactions. Such information, coupled with our identification of specificity‐conferring interactions, should be important for the development of drugs for treatment of the devastating Chagas disease caused by this parasite.
Molecular cloning and expression analysis of the pig small ubiquitin‐like modifier (SUMO) gene family
Authors: Lee J. Y. , Park Y. , Kim S. J. , Park C.‐G. , Chun T.
Published: January 2009

Small ubiquitin‐like modifiers (SUMOs) are structurally related to ubiquitin and are ligated to lysine residues within sumoylation target proteins. Currently, a growing body of evidence shows that the SUMO family has evolved as an important modifier of many proteins in a variety of cellular pathways. In this study, we have cloned cDNA encoding for three different pig SUMO isoforms. The full‐length cDNA encoding for pig Sumo1, Sumo2 and Sumo4 consists of 306, 288 and 288 nucleotide base pairs of the open reading frame, respectively, and the putative amino acid sequences of pig Sumo1, Sumo2 and Sumo4 are composed of 101, 95 and 95 peptides, respectively. The structures of pig SUMOs are evolutionally well conserved, and their expression has been detected in a broad range of tissues. We also determined that all pig SUMOs are localized within the nucleus. However, the different tissue expression observed in individual pig SUMOs may show the divergent or specialized role of each of the pig SUMO isoforms. Future studies will focus on the identification of targets for sumoylation by different pig SUMO isoforms and the analysis of the functional consequences of sumoylation during the course of infectious diseases in pigs.
Reduction of Cerebral Oxidative Stress Following Environmental Enrichment in Mice with Alzheimer‐Like Pathology
Authors: Herring Arne , Blome Mareike , Ambrée Oliver , Sachser Norbert , Paulus Werner , Keyvani Kathy
Published: January 2009

Oxidative stress is a key feature during progression of chronic neurodegenerative conditions such as Alzheimer's disease. In aging humans and animals, voluntary exercise lowers oxidative stress reactions. Additionally, recent work in our lab demonstrated that cognitive and physical stimulation (termed environmental enrichment) counteracts amyloid beta pathology, neurovascular dysfunction and behavioral symptoms in mice with Alzheimer‐like disease. Based on these facts, we hypothesized that cognitive and physical activity can also protect against oxidative stress in Alzheimer‐diseased brain. We, therefore, kept female TgCRND8 mice under standard and enriched housing from day 30 until 5 months of age. Environmental stimulation attenuated pro‐oxidative processes and triggered anti‐oxidative defense mechanisms as indicated by diminished biomarkers for reactive oxygen and nitrogen species, downregulation of pro‐inflammatory and pro‐oxidative mediators, decreased expression of pro‐apoptotic caspases, and upregulation of SOD1 and SOD2. This study identifies a thus far undescribed antagonizing effect of environmental stimulation on Alzheimer's disease‐related oxidative damage.
Relationships between hand‐rolled cigarettes and primary lung cancer: A Norwegian experience
Authors: Rolke Heidi Berg , Bakke Per Sigvald , Gallefoss Frode
Published: January 2009

Introduction:  Detailed smoking history of patients developing lung cancer is rarely known, especially not for users of hand‐rolled cigarettes. In Norway, smoking hand‐rolled tobacco is still popular, accounting for one‐third of the total tobacco consume.

Methods:  A questionnaire‐based study revealing detailed information about tobacco consume with consecutive inclusion of all persons developing lung cancer in Southern Norway 2002–2005.

Results:  In this unselected population with 479 patients with newly diagnosed lung cancer, 95% had a smoking history and 88% of ever‐smokers had smoked primarily hand‐rolled cigarettes. The hand‐rolled cigarette smokers had smoked fewer cigarettes daily (15) and less pack‐years of tobacco (34) than fabricated cigarette smokers (20, P < 0.0001 and 42, P = 0.021, respectively). Smoking hand‐rolled cigarettes was considerably more frequent than expected from official sales statistics. Hand‐rolled cigarette smoking revealed an odds ratio of 13 for developing lung cancer compared with smoking fabricated cigarettes.

Conclusion:  In this unselected population with newly diagnosed lung cancer, nine out of 10 ever‐smokers had smoked primarily hand‐rolled cigarettes. Patients smoking hand‐rolled cigarettes had a smoking history of fewer daily cigarettes and less pack‐years tobacco consumed than fabricated cigarette smokers. In this study, hand‐rolled cigarettes are more frequently used than shown in national statistics.

Smokers of hand‐rolled cigarettes may have a greatly increased risk for lung cancer compared with smokers of fabricated cigarettes.

Please cite this paper as: Rolke HB, Bakke PS and Gallefoss F. Relationships between hand‐rolled cigarettes and primary lung cancer: A norwegian experience. The Clinical Respiratory Journal 2009; 3: 152–160.
Risks of general anesthesia for the special needs dental patient
Authors: Messieha Zakaria
Published: January 2009

The risk of dental rehabilitation under general anesthesia has multiple contributing factors. The literature has addressed the general anesthetic risk of dental general anesthesia and sedation in the operating room and the office settings, but more studies are needed to address the special needs population in particular. There is still a great need for more studies to assess the risk versus benefit for special need population as well as to stratify such risk in order to assist care providers in decision making as well as in sharing such risk concerns with patients, caretakers, and guardians. One recommended approach is to conduct a national retrospective study of patients treated under general anesthesia in the past 10 years in all the various settings and assess the associated risks and complications related to their physical status and the underlying physical and mental disabilities. The product of such a study could be a stratification of risk versus benefit as well as some guidelines for decision making as far as which kind of procedures should be conducted under general anesthesia while weighing the level of risk for the particular patient. Although access to care is not a direct risk factor, it can certainly deter timely treatment and intervention for patients with special needs.
A Conceptual Design Study for a New High Temperature Fast Response Cooled Total Pressure Probe
Authors: Brouckaert Jean-François , Mersinligil Mehmet , Pau Marco
Published: January 2009

The present paper proposes a concept for a water-cooled high temperature unsteady total pressure probe intended for measurements in the hot sections of industrial gas turbines or aero-engines. This concept is based on the use of a conventional miniature piezoresistive pressure sensor, which is located at the probe tip to achieve a bandwidth of at least 40 kHz. Due to extremely harsh conditions and the intention to immerse the probe continuously into the hot gas stream, the probe and sensor must be heavily cooled. The short term objective of this design is to gain the capability of performing measurements at the temperature conditions typically found at high pressure turbine exit (1100–1400 K) and in the long term at combustor exit (2000 K or higher).
Method for Sensitivity Analysis of Resonance Forced Response of Bladed Disks With Nonlinear Contact Interfaces
Authors: Petrov E. P.
Published: January 2009

An effective method has been developed to calculate the sensitivity of the resonance peak frequency and forced response level to variation of parameters of nonlinear friction contact interfaces and excitation. The method allows determination of the sensitivity characteristics simultaneously with the resonance peak frequency and response level calculated as a function of any parameter of interest and without significant computational expense. Capabilities of the method are demonstrated on examples of analysis of large-scale finite element models of realistic bladed disks with major types of the nonlinear contact interfaces: (i) a blisk with underplatform dampers, (ii) a bladed disk with friction damping at blade fir-tree roots, and (iii) a high-pressure bladed disk with shroud contacts. The numerical investigations show high efficiency of the method proposed.
Further Development of a Smoke Sensor for Diesel Engines
Authors: Gould D. , Gardiner D. P. , LaViolette M. , Allan W. D.
Published: January 2009

This paper describes experimental research aimed at developing an on-board smoke sensor for diesel engines. The sensor element was similar to a conventional spark plug. Electrical heating of the insulator was used to prevent carbon fouling from the diesel soot. The sensing element created sparks within the exhaust pipe and changes in smoke levels were detected through analysis of the voltage levels of the sparks. The system was tested in a heavy duty diesel engine equipped with exhaust gas recirculation (EGR) and compared with reference measurements of the filter smoke number (FSN). The experiments showed good sensitivity to step changes in smoke levels (accomplished by varying EGR levels) at smoke levels below 0.5 FSN. However, the sensor suffered from temperature induced signal drift and was unstable under some circumstances. The use of a spark plug with a smaller electrode tip diameter improved the signal stability. It is proposed that measurement and control of the electrode temperature will be necessary to control the signal drift.
On Moore’s Law and Its Application to Spark Ignition Engine Technology
Authors: LaViolette Marc
Published: January 2009

Moore’s law relates how the integration of semiconductors has progressed in time. This research shows that the exponential trend shown in the electronics manufacturing industry can have applications elsewhere. This study shows that the internal combustion engine followed the same trend for over 70 years. Though not the most used engine variable, engine power density shows the same trends for engines as transistor density does for microchips. This now mature technology has ended its period of rapid growth. However, the present day engine trends can show how Moore’s law can be extended to include the slower growth of long established technologies. Because exponential growth cannot go on forever, the extension Moore’s law requires that the logistic function be used. The new function also allows one to predict a theoretical value for maximum power density.
Fatigue Crack Growth Behavior Evaluation of Grainex Mar-M 247 for NASA’s High Temperature High Speed Turbine Seal Test Rig
Authors: Delgado Irebert R. , Steinetz Bruce M. , Rimnac Clare M. , Lewandowski John J.
Published: January 2009

The fatigue crack growth behavior of Grainex Mar-M 247 is evaluated for NASA’s turbine seal test facility. The facility is used to test air-to-air seals primarily for use in advanced jet engine applications. Because of extreme seal test conditions of temperature, pressure, and surface speeds, surface cracks may develop over time in the disk bolt holes. An inspection interval is developed to preclude catastrophic disk failure by using experimental fatigue crack growth data. By combining current fatigue crack growth results with previous fatigue strain-life experimental work, an inspection interval is determined for the test disk. The fatigue crack growth life of NASA disk bolt holes is found to be 367cycles at a crack depth of 0.501mm using a factor of 2 on life at maximum operating conditions. Combining this result with previous fatigue strain-life experimental work gives a total fatigue life of 1032cycles at a crack depth of 0.501mm. Eddy-current inspections are suggested starting at 665cycles since eddy current detection thresholds are currently at 0.381mm. Inspection intervals are recommended every 50cycles when operated at maximum operating conditions.
Development of an Innovative Plate-Type SG for Sodium Cooled Fast Reactor: Concept and Test Fabrication
Authors: Nishi Yoshihisa , Kinoshita Izumi
Published: January 2009

The concept of an innovative plate-type steam generator (SG) for a fast reactor, fabricated using hot isostatic pressing (HIP), was presented. The heat-transfer plate, which is assembled with rectangular tubes and fabricated using HIP, is surrounded by a leak-detection layer. The optimum form for the detection layer was determined by crack extension analysis. The concept can be applied in both pool-type and loop-type liquid-metal cooled fast reactors (LMFRs). In this report, the fabrication technique is described as applied to a loop-type LMFR. Optimum HIP conditions of 1423 K (1150°C), 1200 kgf/cm2(117 MPa), and 3 h for modified 9Cr–1Mo steel were determined from HIP tests, tensile tests, and structural inspection. Nickel-type solder (BNi-5) and gold-type solder (BAu-4) were examined as potential joining materials to laminate the heat-transfer plates. Tensile test comparisons showed that BAu-4 was superior, so it was used. No problems were observed in the fabrication of a partial model of a SG (HIP of the rectangular tubes, brazing the plates, welding the header, etc.)
Transient Three-Dimensional Stability Analysis of Supercritical Water Reactor Rod Bundle Subchannels by a Computatonal Fluid Dynamics Code
Authors: Sharabi M. , Ambrosini W. , He S. , Jiang Pei-Xue , Zhao Chen-Ru
Published: January 2009

The paper describes the application of computational fluid dynamics (CFD) in simulating density wave oscillations in triangular and square pitch rod bundles. The FLUENT code is used for this purpose, addressing typical conditions proposed for supercritical water reactor (SCWR) conceptual design. The RELAP5 code and an in-house 1D linear stability code are also adopted to compare the results for instability thresholds obtained by different techniques. Transient analyses are performed both by the CFD code and RELAP5, with increasing heating rates and constant pressure drop across the channel, up to the occurrence of unstable behavior. The obtained results confirm that the density wave mechanism is similar in rod bundle and in axisymmetric configurations.
Weld Material Investigations of a WWER-440 Reactor Pressure Vessel: Results From the First Trepan Taken From the Former Greifswald NPP
Authors: Rindelhardt Udo , Viehrig Hans-Werner , Konheiser Joerg , Schuhknecht Jan
Published: January 2009

Between 1973 and 1990 four units of the Russian nuclear power plants type WWER-440/230 were operated in Greifswald (former East Germany). Material probes from the pressure vessels were gained in the frame of the ongoing decommissioning procedure. The investigations of this material started with material from the circumferential core weld of unit 1. First, this paper presents results of the reactor pressure vessel (RPV) fluence calculations depending on different loading schemes and on the axial weld position based on the Monte Carlo code TRAMO. The results show that the use of the dummy assemblies reduces the flux by a factor of 2–5 depending on the azimuthal position. The circumferential core weld (SN0.1.4) received a fluence of 2.4×1019 neutrons/cm2 at the inner surface; it decreases to 0.8×1019 neutrons/cm2 at the outer surface. The material investigations were done using a trepan from the circumferential core weld. The reference temperature T0 was calculated with the measured fracture toughness values, KJc, at brittle failure of the specimen. The KJc values show a remarkable scatter. The highest T0 was about 50°C at a distance of 22 mm from the inner surface of the weld. The Charpy transition temperature TT41J estimated with results of subsized specimens after the recovery annealing was confirmed by the testing of standard Charpy V-notch specimens. The VERLIFE procedure prepared for the integrity assessment of WWER RPV was applied on the measured results. The VERLIFE lower bound curve indexed with the Structural Integrity Assessment Procedures for European Industry (SINTAP) reference temperature, RTT0SINTAP, envelops the KJc values. Therefore for a conservative integrity assessment the fracture toughness curve indexed with a RT representing the brittle fraction of a data set of measured KJc values has to be applied.
Air/Water Counter-Current Flow Experiments in a Model of the Hot Leg of a Pressurized Water Reactor
Authors: Vallée Christophe , Deendarlianto  , Beyer Matthias , Lucas Dirk , Carl Helmar
Published: January 2009

Different scenarios of small break loss of coolant accident for pressurized water reactors (PWRs) lead to the reflux-condenser mode in which steam enters the hot leg from the reactor pressure vessel (RPV) and condenses in the steam generator. A limitation of the condensate backflow toward the RPV by the steam flowing in counter current could affect the core cooling and must be prevented. The simulation of counter-current flow limitation conditions, which is dominated by 3D effects, requires the use of a computational fluid dynamics (CFD) approach. These numerical methods are not yet mature, so dedicated experimental data are needed for validation purposes. In order to investigate the two-phase flow behavior in a complex reactor-typical geometry and to supply suitable data for CFD code validation, the “hot leg model” was built at Forschungszentrum Dresden-Rossendorf (FZD). This setup is devoted to optical measurement techniques, and therefore, a flat test-section design was chosen with a width of 50 mm. The test section outlines represent the hot leg of a German Konvoi PWR at a scale of 1:3 (i.e., 250 mm channel height). The test section is mounted between two separators, one simulating the RPV and the other is connected to the steam generator inlet chamber. The hot leg model is operated under pressure equilibrium in the pressure vessel of the TOPFLOW facility of FZD. The air/water experiments presented in this article focus on the flow structure observed in the region of the riser and of the steam generator inlet chamber at room temperature and pressures up to 3 bar. The performed high-speed observations show the evolution of the stratified interface and the distribution of the two-phase mixture (droplets and bubbles). The counter-current flow limitation was quantified using the variation in the water levels measured in the separators. A confrontation with the images indicates that the initiation of flooding coincides with the reversal of the flow in the horizontal part of the hot leg. Afterward, bigger waves are generated, which develop to slugs. Furthermore, the flooding points obtained from the experiments were compared with empirical correlations available in literature. A good overall agreement was obtained, while the zero penetration was found at lower values of the gaseous Wallis parameter compared with previous work. This deviation can be attributed to the rectangular cross section of the hot leg model.
Effect of CANDU Bundle-Geometry Variation on Dryout Power
Authors: Leung Laurence K. H.
Published: January 2009

Dryout powers have been evaluated at selected inlet-flow conditions for two proposed designs of Canada deuterium uranium, CANDU® (a registered trademark of Atomic Energy of Canada Limited (AECL)) bundles and compared with those of the 37-element and CANDU Flexible, CANFLEX® (a registered trademark of AECL and Korea Atomic Energy Research Institutes (KAERI)) bundles. These proposed designs consist of a large center element (18 mm for one design and 20 mm for the other) and three rings of elements of 11.5 mm in outer diameter. The critical heat flux for each bundle design has been predicted using the correlation derived with Freon data obtained from the corresponding full-scale bundle test. An improvement in dryout power has been shown for the proposed design having a 20 mm center element with a radial power profile corresponding to the natural-uranium fuel as compared with other bundles, particularly the natural-uranium 37-element bundle, with a symmetric-cosine axial power profile. The dryout power improvement is further enhanced for the upstream-skewed axial power profile.
Numerical Prediction and Optimization of Depressurized Sodium-Water Reaction Experiment With Counterflow Diffusion Flame
Authors: Yamaguchi Akira , Takata Takashi , Ohshima Hiroyuki , Kohara Yoshitaka , Deguchi Yoshihiro
Published: January 2009

Sodium-water reaction (SWR) is a design basis accident of a sodium-cooled fast reactor (SFR). A breach of the heat transfer tube in a steam generator results in contact of liquid sodium with water. Typical phenomenon is that the pressurized water blows off, vaporizes, and mixes with the liquid sodium. It is necessary to quantify the SWR phenomena in the safety evaluation of the SFR system. In this paper, a new computer program has been developed and the SWR in a counterflow diffusion flame is studied by a numerical simulation and an experiment. The experiment is designed based on the numerical simulation so that the stable reaction flame is maintained for a long time and physical and chemical quantities are measured. From the comparison of the analysis and the experiment, there exist discrepancies that may be caused by the assumptions of the chemical reaction. Hence, a new experiment is proposed to enhance the measurement accuracy and to investigate the reason of the disagreement. The authors propose a depressurized experiment and show the preliminary result of the experiment. It is found that a stable chemical reaction flame is formed. With the depressurization, it is expected that the flame location can be controlled and the reaction region becomes thicker because of decrease in the reactant gas density.
Effect of copper emitted from wafers on etch rates of insulator films in capacitively coupled fluorocarbon plasma
Authors: Imai Shin-ichi
Published: January 2009

This article describes the effects of copper emitted from wafers on the etch rates of two kinds of insulator films and discusses copper detection by optical emission spectroscopy (OES) and by a plasma impedance monitor (PIM). Plasma etching of a silicon nitride (SiN) film on a copper film in a passivation layer process is performed using capacitively coupled CHF3∕CF4∕O2∕Ar plasma at 1400W rf power, 250mTorr pressure, total flow of 330SCCM (SCCM denotes cubic centimeter per minute at STP), and etch time fixed at 30s. Under these conditions, it is confirmed that copper is emitted from a wafer into fluorocarbon plasma during overetching of the SiN film and that it adheres to a process chamber wall. The concentration of emitted copper is measured by atomic absorption spectroscopy (AAS) to be about 3×1010atoms∕cm2, and the maximum concentration adhering to the process chamber wall is expected to be 1.2×1015atoms∕cm2 by considering the collection efficiency of copper in AAS. With the increase in the cumulative etch time of a SiN film on a copper film, the concentration of copper sticking to the process chamber wall increases. With additional copper concentration, the etch rate of a SiN film decreases but that of a silicon dioxide (SiO2) film increases. The copper emission into the fluorocarbon plasma can be detected by observing plasma impedance using PIM and optical intensities using OES. These results indicate an increase in plasma density due to the copper emission. Furthermore, x-ray photoelectron spectroscopy measurements on the etched surfaces of SiN and SiO2 films reveal that the mechanism of the etch rate changes: A thicker polymer film is deposited on the SiN film than on the SiO2 film. This indicates that the change in radical composition of fluorocarbon plasma is caused by the catalytic effect of copper on the process chamber wall. Since the thick polymer film inhibits etching reaction between the SiN film and the etching species, the etch rate of the SiN film decreases. On the other hand, on the SiO2 film, the polymer film is thin and the current flowing into the wafer increases due to the increased plasma density. Since the etching species to the wafer increases, the etch rate of the SiO2 film also increases.
Selective formation of competitive c-axis and a-axis oriented LiNbO3 epitaxial films on Al2O3(112¯0)
Authors: Akazawa Housei
Published: January 2009

The crystallographic orientation of epitaxial LiNbO3 films on the Al2O3(112¯0) substrate can be controlled either toward the c-axis or a-axis depending on the situation at crystallization. Crystallization during high-rate sputter deposition at elevated temperatures produced c-axis-oriented film with 60°-rotated twin domains. Minimizing the surface energy when the growing surface was exposed to abundant ion flux selected (0001) terminated mosaic crystal. In contrast, solid-phase crystallization or as crystallization during a low-rate sputter deposition yielded a-axis-oriented film coexisting with 180° polarization twin domains. The enhanced migration of atoms in low-density amorphous film as well as pseudomorphic lattice matching growth under thermal equilibrated conditions led to the self-organization of relaxed crystalline domains.
Crystallographic texture control of sputtered HfN thin films using low oxygen partial pressures
Authors: Deniz D. , Harper J. M. E.
Published: January 2009

The authors studied the development of crystallographic texture in hafnium nitride (HfN) films deposited by off-normal incidence reactive magnetron sputtering at room temperature. Films are prepared with and without added oxygen in N2∕Ar mixtures. Texture measurements were performed by x-ray pole figure analysis of the (111) and (200) diffraction peaks. The authors found that HfN deposited at 40° without added oxygen has a strong ⟨100⟩ fiber texture with no in-plane alignments showing the dominance of thermodynamic effects in the course of texture evolution. Oxygen is deliberately introduced into the sputtering gas ambient to study its effects on microstructure formation. As the oxygen partial pressure (O2 pp) is increased in the range of 1.33×10−5to1.33×10−4Pa, HfN out-of-plane orientation changed to ⟨111⟩ with a substantial in-plane alignment in ⟨100⟩ direction as well. In this case, texture analysis of each individual diffraction peak revealed the existence of two populations of grains indicating a competition between (111) and (200) planes. A transition towards hafnium oxynitride phases occurred at high O2 pp’s. The authors propose that oxygen presence during deposition reduces the adatom surface mobility, which enables kinetic effects to govern the texture formation and thus leads to a biaxial alignment in HfN films.
Computational and experimental study of gas flows through long channels of various cross sections in the whole range of the Knudsen number
Authors: Varoutis Stelios , Naris Steryios , Hauer Volker , Day Christian , Valougeorgis Dimitris
Published: January 2009

A computational and experimental study has been performed for the investigation of fully developed rarefied gas flows through channels of circular, orthogonal, triangular, and trapezoidal cross sections. The theoretical-computational approach is based on the solution of the Bhatnagar-Gross-Krook kinetic equation subject to Maxwell diffuse-specular boundary conditions by the discrete velocity method. The experimental work has been performed at the vacuum facility “TRANSFLOW,” at Forschungszentrum Karlsruhe and it is based on measuring, for assigned flow rates, the corresponding pressure differences. The computed and measured mass flow rates and conductance are in all cases in very good agreement. In addition, in order to obtain some insight in the flow characteristics, the reference Knudsen, Reynolds, and Mach numbers characterizing the flow at each experimental run have been estimated. Also, the pressure distribution along the channel for several typical cases is presented. Both computational and experimental results cover the whole range of the Knudsen number.
Photoluminescence from Er-doped Si-rich Si oxides deposited by magnetron sputtering in Ar or Ar+H2 plasmas
Authors: Heng C. L. , Chelomentsev E. , Zalloum O. H. Y. , Wojcik J. , Mascher P.
Published: January 2009

The authors have studied photoluminescence (PL) from Er-doped Si-rich Si oxide (SRSO) films deposited by magnetron sputtering of an Er+Si+SiO2 composite target in Ar or Ar+H2 ambients. When the samples were annealed in N2, for the film grown in an Ar ambient, the PL annealing behaviors reveal that the emissions from the film are defect-related and that the Er3+ PL at 1.54μm is possibly triggered by a defect-mediated energy transfer process; while for the films grown in an Ar+H2 ambient, the emissions from the SRSO matrix are suppressed and the Er PL intensities increase significantly but differently dependent on the Ar:H2 ratios during sputtering. After annealing the samples in an Ar+5%H2 (FG) ambient, however, almost no Er PL was observed from the film grown in the Ar ambient, while the Er PL intensities of the films grown in the Ar+H2 ambient increase further compared to those annealed in N2. Fourier transform infrared spectroscopy shows that the absorption of the samples after FG annealing is weaker than after annealing in N2. The PL properties have also been compared to those of a sample grown by plasma enhanced chemical vapor deposition. The roles of hydrogen during sputtering and postdeposition annealing are discussed.
Dilute hydrogen plasma cleaning of boron from silicon after etching of HfO2 films in BCl3 plasmas: Substrate temperature dependence
Authors: Wang Chunyu , Donnelly Vincent M.
Published: January 2009

The authors have investigated the effects of elevated substrate temperature (Ts) on cleaning of boron residues from silicon substrates in 1%H2–Ar plasmas, following etching of HfO2 in BCl3 plasmas. Vacuum-transfer x-ray photoelectron spectroscopy (XPS) provided a measure of total B removal rates, as well as information on individual BClxOy moities. B cleaning rates increased with Ts in an Arrhenius manner, with an apparent activation energy of 1.7kcal∕mol. Conversely, the Si etching rate decreased with increasing substrate temperature with an apparent activation energy of −0.8kcal∕mol. Therefore, when considering selectivity with respect to Si etching, it is advantageous to remove B at higher Ts. For example, at Ts=235°C, ∼90% of B is cleaned from Si in 10s, while <1.5nm of Si is removed. An apparent diffusion of H into the near-surface region of Si at higher temperatures, detected indirectly by a shift and broadening of the Si(2p) XPS peak, may limit the maximum optimum substrate temperature, however. It was also found that Si does not etch in 1%H2∕Ar plasmas if an oxide layer is present.
Characterization of low-temperature silicon nitride films produced by inductively coupled plasma chemical vapor deposition
Authors: Xu Q. , Ra Y. , Bachman M. , Li G. P.
Published: January 2009

Silicon nitride films were synthesized at 170°C by using inductively coupled plasma chemical vapor deposition under three microwave power conditions of 500, 800, and 1000W. The chemical, physical and electrical properties of the deposited silicon nitride films were characterized by Fourier transform infrared, wet etching, atomic force microscopy, ellipsometry, J-V, and C-V measurements of metal-insulator-semiconductor. The microwave power for film deposition is found to play an important role at the films’ properties. A high microwave power reduces the retention of hydrogen in a form of Si–H and N–H atomic bonds. The microwave power significantly affects the density of pin holes; the 800W film has the lowest density of pin holes. In general, the low-temperature silicon nitride films possess better surface roughness than the conventional silicon nitride films produced at higher temperatures. The low-temperature silicon nitride films exhibit an abrupt breakdown, a characteristic of avalanche breakdown. The variation in breakdown strength is correlated with the change in pin-hole density, and the 800W silicon nitride film possesses the highest breakdown strength. The microwave power has limited influences on leakage current and resistivity of the films. All the low-temperature silicon nitride films are characterized by high-density fixed charges and interface charge traps, of which both densities vary slightly with the microwave power for film deposition.
Feedback control of plasma electron density and ion energy in an inductively coupled plasma etcher
Authors: Lin Chaung , Leou Keh-Chyang , Huang Hong-Min , Hsieh Cheng-Hung
Published: January 2009

Here the authors report the development of a fuzzy logic based feedback control of the plasma electron density and ion energy for high density plasma etch process. The plasma electron density was measured using their recently developed transmission line microstrip microwave interferometer mounted on the chamber wall, and the rf voltage was measured by a commercial impedance meter connected to the wafer stage. The actuators were two 13.56 MHz rf power generators which provided the inductively coupled plasma power and bias power, respectively. The control system adopted the fuzzy logic control algorithm to reduce frequent actuator action resulting from measurement noise. The experimental results show that the first wafer effect can be eliminated using closed-loop control for both poly-Si and HfO2 etching. In particular, for the HfO2 etch, the controlled variables in this work were much more effective than the previous one where ion current was controlled, instead of the electron density. However, the pressure disturbance effect cannot be reduced using plasma electron density feedback.
Biological optimization of tumor radiosurgery
Authors: Cappuccio Antonio , Herrero Miguel A. , Nuñez Luis
Published: January 2009

In tumor radiosurgery, a high dose of radiation is delivered in a single session. The question then naturally arises of selecting an irradiation strategy of high biological efficiency. In this study, the authors propose a mathematical framework to investigate the biological effects of heterogeneity and rate of dose delivery in radiosurgery. The authors simulate a target composed by proliferating and hypoxic tumor cells as well as by normal tissue. Treatment outcome is evaluated by a functional of the dose distribution that counts the LQ‐surviving fractions of each cell type. Prescriptions on intensity, homogeneity, and duration of radiation delivery are incorporated as constraints. Biological optimization is performed by means of calculus of variation techniques. For a fixed dose, increasing heterogeneity considerably improved the biological performance. The dose peaks progressively concentrated in the hypoxic and proliferating areas, while damage to normal tissue was reduced. The duration of delivery, optimized in the range of and for various tumor/normal characteristic DNA repair time ratios, coincided with the maximum allowed value. It resulted in a poor therapeutic gain, which was positively correlated with the tumor/normal characteristic DNA repair time ratio. The mathematical framework described in this work allows one to design the dose distribution and dose rate of biologically based plans for tumor radiosurgery. It may be thus integrated into the available simulation softwares to assist in treatment planning.