bluuebunny/crossref_metadata_2025 huggingface dataset:
Cosupplementation of Dietary Calcium and Conjugated Linoleic Acid (CLA) Improves Bone Mass in Mice
Authors: Park Y. , Pariza M.W. , Park Y.
Published: July 2008

ABSTRACT:  Conjugated linoleic acid (CLA) has shown a variety of biologically beneficial effects, such as anticancer, antiatherosclerosis, antidiabetic, immunomodulating, and antiobesity effects. Its effects on reduction of body fat occur with enhancement of lean body mass and body ash; the effects of CLA on bone mass are inconsistent in mice and human studies. We hypothesized that the inconsistency of CLA's effect on ash may be linked to interaction between CLA and dietary calcium levels. We reanalyzed our previous studies, which used mice fed 0.5% CLA‐containing diet with regular calcium content (0.5%) or enhanced calcium level (0.66%). Extra calcium in the diet improved CLA's effects on bone mass, particularly in male mice (P= 0.0194); without extra dietary calcium there was no effect of CLA on bone mass. This finding may help improve the efficacy of CLA to be used as a dietary supplement to be used as part of an osteoporosis prevention strategy. Further studies are needed to confirm this observation.
Antioxidant Effects of Flavonoids Used as Food Additives (Purple Corn Color, Enzymatically Modified Isoquercitrin, and Isoquercitrin) on Liver Carcinogenesis in a Rat Medium‐Term Bioassay
Authors: Yokohira M. , Yamakawa K. , Saoo K. , Matsuda Y. , Hosokawa K. , Hashimoto N. , Kuno T. , Imaida K.
Published: July 2008

ABSTRACT:  To clarify the effects of purple corn color, enzymatically modified isoquercitrin (EMIQ), and isoquercitrin (IQ), registered as natural food additives in Japan, on liver carcinogenesis in vivo, a medium‐term bioassay was employed. A total of 100 male F344 rats were divided into 5 groups; groups 1 to 4 were given a single intraperitoneal injection of diethylnitrosamine (200 mg/kg b.w.) on day 1. From weeks 2 to 8, they were administered basal diet purple corn color, EMIQ, or IQ as containing test chemicals at doses of 1.0% (groups 1 and 5), 0.1% (group 2), 0.01% (group 3), or 0% (group 4) (experiments 1, 4, and 5). All rats were subjected to two‐thirds partial hepatectomy at week 3 and were sacrificed at week 8. Purple corn color exerted no significant modifying effects on GST‐P positive foci, preneoplastic foci, development in the liver. However, serum of rats treated with purple corn color provided evidence of antioxidant power significantly by potential antioxidant (PAO) test in vivo (experiment 2). And microarray analyses showed purple corn color to induce RNA expression such as P450 (cytochrome) oxidoreductase, phosphatidylinositol 3‐kinase, and phospholipase A2 (experiment 3). Higher doses of EMIQ or IQ with strong antioxidant power in vivo by PAO test treated groups were correlated with smaller numbers of GST‐P positive foci, with Spearman's rank correlation coefficients of P= 0.002 and P= 0.049, respectively (experiments 4 and 5). Therefore, the tested food additives may be effective as antioxidants in vivo and have chemopreventive potential against liver preneoplastic lesion development.
Effects of meloxicam or tolfenamic acid administration on the pain and stress responses of Merino lambs to mulesing
Authors: Paull DR , Lee C , Atkinson SJ , Fisher AD
Published: July 2008

Objective To determine the effectiveness of two long‐acting non‐steroidal anti‐inflammatory drugs (NSAIDs) at reducing the pain and stress responses to mulesing in lambs.

Procedures Merino lambs (n = 60) were allocated at 5 weeks of age to six treatment groups: (1) sham mules; (2) mules; (3) tolfenamic acid‐sham mules; (4) tolfenamic acid administered 45 min before mulesing; (5) tolfenamic acid at the time of mulesing; (6) meloxicam at the time of mulesing. Plasma cortisol was measured at −0.75, −0.25, 0, 0.5, 1, 3, 6, 12, 24, 48 and 72 h relative to mulesing. Beta‐endorphin concentrations in plasma were determined at 0, 0.5, 1, 6, 12, 24, and 48 h. Haematology was performed on blood samples taken at −0.75, 0, 24, 48 and 72 h. Plasma haptoglobin was measured at 0, 12, 24, 48 and 72 h. Rate of wound healing was determined 72 h post mulesing, and animal behaviour, including posture, was measured for 6 h after mulesing.

Results The mulesed lambs exhibited large increases in plasma concentrations of cortisol, beta‐endorphin and haptoglobin. All mulesed animals lost weight significantly in the week after mulesing, regardless of analgesic administration, but the difference in weight between mulesed and unmulesed lambs was less at the final measurement, 2 weeks after mulesing. Mulesed lambs spent significantly less time lying ventrally than control lambs. All lambs that were mulesed, including those administered NSAIDs, spent more time standing with a hunched posture and less time walking normally than control lambs.

Conclusions The NSAID treatments applied 45 min before or at the time of mulesing at the dose levels used in this study were not effective in reducing the acute response of lambs to mulesing.
UV Radiation: Balancing Risks and Benefits†
Authors: McKenzie Richard L. , Liley J. Ben , Björn Lars Olof
Published: July 2008

We use action spectra published by the International Commission on Illumination to examine diurnal, seasonal and latitudinal variations in erythemally weighted (sunburning) UV—a health risk, and vitamin D‐weighted UV—a health benefit. Vitamin D‐weighted UV is more strongly dependent on ozone and solar zenith angle. Consequently, its diurnal, seasonal and geographic variability is more pronounced than for erythemally weighted UV. We then investigate relationships between the two quantities. An algorithm is developed and used to relate vitamin D production to the widely used UV index, to help the public to optimize their exposure to UV radiation. In the summer at noon, there should at mid‐latitudes be sufficient UV to photosynthesize optimal vitamin D in ∼1 min for full body exposure, whereas skin damage occurs after ∼15 min. Further, while it should be possible to photosynthesize vitamin D in the winter at mid‐latitudes, the amount of skin that must be exposed is larger than from the hands and face alone. This raises the question of whether the action spectrum for vitamin D production is correct, since studies have reported that production of vitamin D is not possible in the winter at mid‐latitudes.
Intergroup Emotions and Intergroup Relations
Authors: Mackie Diane M. , Smith Eliot R. , Ray Devin G.
Published: July 2008

Intergroup emotions theory seeks to understand and improve intergroup relations by focusing on the emotions engendered by belonging to, and by deriving identity from, a social group (processes called self‐categorization and identification). Intergroup emotions are shaped by the very different ways in which members of different groups see group‐relevant objects and events. These emotions come, with time and repetition, to be part and parcel of group membership itself. Once evoked, specific intergroup emotions direct and regulate specific intergroup behaviors. This approach has implications for theories of emotion as well as of intergroup relations. Because intergroup emotions derive from self‐categorization and identification and because they strongly influence intergroup behavior, intergroup emotions theory provides an innovative framework for attempts to reduce prejudice and improve intergroup relations.
Current Controversies in the Study of Personality across Cultures
Authors: Church A. Timothy
Published: July 2008

Research on culture and personality is thriving. In this article, I address several prominent controversies, including: (a) alternative perspectives on the relationship between culture and personality; (b) the cross‐cultural universality versus specificity of personality structure; (c) whether comparisons of mean inventory profiles reveal valid cultural differences in trait levels; and (d) the importance and role of the trait concept across cultures. Greater consensus regarding the relationship between culture and personality will likely be achieved if researchers clarify which aspects of personality they are addressing (e.g., basic tendencies vs. characteristic adaptations). Recent lexical and indigenous studies have weakened consensus regarding the universality and comprehensiveness of the Five‐Factor Model. The validity of cultural mean profiles remains unresolved. Research on the importance of traits across cultures provides support for both trait and cultural psychology perspectives, although more culture‐comparative studies of consistency and predictive validity are needed. Suggestions for research are offered.
A Cultural Analysis of the Experiment and an Experimental Analysis of Culture
Authors: Adams Glenn , Stocks Eric L.
Published: July 2008

What is it that one can and cannot learn from experiments? The present paper addresses this question from the perspective of cultural psychology. The first half of the paper examines implicit constructions of reality – like individualism, assumptions about the purity of the experimental context and the nature of mind, and the meaning of empirical– that constitute the culture of experimental social psychology. The second half of the paper illustrates an experimental approach to the study of culture with an example from a program of research on enemyship. Overall, the paper suggests that experimental methods may be best suited for arguments about proximal cause, but less appropriate for arguments about the distal causes of events in the everyday world. Rather than advocate that social psychologists abandon the experiment, a cultural psychology perspective suggests the reflexive use of experimental methods in conjunction with multiple techniques of empirical observation.
Developing an Acceptability Assessment of Preventive Dental Treatments
Authors: Hyde Susan , Gansky Stuart A. , Gonzalez‐Vargas Maria J. , Husting Sheila R. , Cheng Nancy F. , Millstein Susan G. , Adams Sally H.
Published: July 2008

Objectives: Early childhood caries (ECC) is very prevalent among young Hispanic children. ECC is amenable to a variety of preventive procedures, yet many Hispanic families underutilize dental services. Acceptability research may assist in health care planning and resource allocation by identifying patient preferences among efficacious treatments with the goal of improving their utilization. The purposes of this study were (a) to develop a culturally competent acceptability assessment instrument, directed toward the caregivers of young Hispanic children, for five preventive dental treatments for ECC and (b) to test the instrument's reliability and validity. Methods: An instrument of five standard treatments known to prevent ECC was developed, translated, reviewed by focus groups, and pilot tested, then tested for reliability. The instrument included illustrated cards, brief video clips, and samples of the treatments and was culturally appropriate for low‐income Hispanic caregivers. In addition to determining the acceptability of the five treatments individually, the treatments were also presented as paired comparisons. Results: Focus groups and debriefing interviews following the pilot tests established that the instrument has good face validity. The illustrated cards, product samples, and video demonstrations of the five treatments resulted in an instrument possessing good content validity. The instrument has good to excellent test–retest reliability, with identical time 1–time 2 responses for each of the five treatments 92 percent of the time (range 87 to 97 percent), and the same treatment of the paired comparisons preferred 75 percent of the time (range 61 to 90 percent). Conclusions: The acceptability instrument described is reliable and valid and may be useful in program planning efforts to identify and increase the utilization of preferred ECC preventive treatments for target populations.
Objective, Subjective, and Self‐Assessment of Preadolescent Orthodontic Treatment Need – A Function of Age, Gender, and Ethnic/Racial Background?
Authors: Christopherson Elizabeth A. , Briskie Dan , Inglehart Marita Rohr
Published: July 2008

Children from socioeconomically disadvantaged and/or underrepresented minority backgrounds in the United States have limited or no access to orthodontic treatment. Objectives: To determine whether preadolescents' (a) objectively assessed orthodontic treatment need; (b) subjectively assessed orthodontic treatment need; and (c) self‐perceptions of the psychologic aspects of their oral health‐related quality of life and desire to have braces vary as a function of age, gender, ethnicity/race, and socioeconomic status (SES). Methods: Data were collected from 1,566 preadolescents (age range: 8 to 11 years; 47.3 percent male/52.7 percent female; 55.7 percent African‐American/39.7 percent White/2.9 percent Hispanic) in oral exams and in face to face interviews. Malocclusion was determined with the Index of Orthodontic Treatment Need. Results: Children (17.2 percent) had definite treatment need, 33.7 percent were borderline, and 49.1 percent had little or no need. Objectively and subjectively assessed treatment need was not affected by the children's age or gender. However, girls were more critical of their smiles and wanted braces more than boys. The older the children were, the more critical they were and the more they wanted braces. African‐American children and children in schools with higher percentages of children on free school lunches had less treatment need than White children and children in schools with lower percentages of students with free school lunches. While the provider‐assessed treatment need was higher for White children than for Black children, Black children were less happy with their smiles than White children, and wanted braces more than White children. SES did not affect the children's self‐perceptions. Conclusions: Findings showed that substantial percentages of the preadolescents have an orthodontic treatment need. Orthodontic need and child self‐perceptions varied as a function of the children's age, gender, ethnicity/race, and SES.
Racial Differences in Baseline Treatment Preference as Predictors of Receiving a Dental Extraction Versus Root Canal Therapy During 48 Months of Follow‐Up
Authors: Boykin Michael J. , Gilbert Gregg H. , Tilashalski Ken R. , Litaker Mark S.
Published: July 2008

Objective: This study aimed to test hypotheses that: a) treatment preference as stated at baseline predicts subsequent receipt of extraction (EXT) versus root canal treatment; and b) racial differences in treatment preference at baseline account for racial differences in receipt of these treatments during follow‐up. Methods: Data were taken from the Florida Dental Care Study. This stratified random sample included at baseline 873 subjects, all of whom were 45 years old or older, reported race as non‐Hispanic African American or non‐Hispanic white, and had at least one tooth. At baseline, participants were asked about past dental care characteristics, history of or current presence of various dental diseases and conditions, and sociodemographic circumstance. An EXT/root canal treatment “CHOICE” scenario was also queried at baseline. Predisposing, enabling, and need factors were tested as predictors of EXT/root canal treatment received during follow‐up. Bivariate multivariable logistic regression analyses quantified associations between the outcomes (EXT/root canal) and the predictors. Results: Receipt of EXT or root canal treatment during follow‐up was strongly related to race even after people with mobile teeth at baseline were excluded from the analysis. Certain baseline factors (tooth mobility, periodontal attachment level, and ability to pay an unexpected dental bill) strongly predicted EXT/root canal treatment receipt during follow‐up, although significant race effects remained; however, including “CHOICE” removed the race effect. Conclusions: Baseline treatment preference strongly predicts subsequent receipt of EXT versus root canal treatment. Racial differences in treatment received during follow‐up were explained by baseline racial differences in treatment preference, tooth mobility, and periodontal status.
Oral Disease Burden and Utilization of Dental Care Patterns Among Pediatric Solid Organ Transplant Recipients
Authors: Shiboski Caroline H. , Kawada Phyllis , Golinveaux Megan , Tornabene Ann , Krishnan Sumathi , Mathias Robert , Den Besten Pamela , Rosenthal Philip
Published: July 2008

Objectives: We conducted a study among pediatric renal (RTRs) and liver transplant recipients (LTRs) to determine: a) the overall burden of oral disease; and b) the frequency with which this population utilizes dental care services in relation to sociodemographic factors and oral disease burden. Methods: In this cross‐sectional survey, study procedures included the completion of a standardized questionnaire (by parents/guardians), oral mucosal examination, assessment of caries, gingival enlargement, and plaque index. Results: The 142 children (82 RTRs and 60 LTRs) enrolled from April 2002 to November 2005 were predominantly Latino (41 percent) and Caucasian (34 percent). Forty‐three percent had at least one carious surface (in either a deciduous or permanent tooth), 19 percent had five or more carious surfaces, and 25 percent had gingival enlargement. We found only one case of oral candidiasis. Even though 72 percent of parents/guardians reported their child had a regular source of dental care, only 49 percent had a dental cleaning and 44 percent had dental radiographs in the past year, reflecting a low prevalence of preventive dental care. Among children with no regular source of dental care, there were statistically significantly higher proportions of Latinos, younger children, and families with an annual household income <$35,000. Conclusion: While the prevalence of oral mucosal disease and gingival enlargement was low, the prevalence of children with caries was high, and there was low use of preventive dental care. Strategies to improve this population's utilization of preventive dental care are needed.
Is the Child Oral Health Quality of Life Questionnaire Sensitive to Change in the Context of Orthodontic Treatment? A Brief Communication
Authors: Agou Shoroog , Malhotra Monika , Tompson Bryan , Prakash Preeti , Locker David
Published: July 2008

Objective: This study aimed to assess the ability of the Child Oral Health Quality of Life Questionnaire (COHQoL) to detect change following provision of orthodontic treatment. Methods: Children were recruited from an orthodontic clinic just prior to starting orthodontic treatment. They completed a copy of the Child Perception Questionnaire, while their parents completed a copy of the Parents Perception Questionnaire and the Family Impact Scale. Normative outcomes were assessed using the Dental Aesthetic Index (DAI) and the Peer Assessment Rating (PAR) index. Change scores and effect sizes were calculated for all scales. Results: Complete data were collected for 45 children and 26 parents. The mean age was 12.6 years (standard deviation = 1.4). There were significant pre‐/posttreatment changes in DAI and PAR scores and significant changes in scores on all three questionnaires (P < 0.05). Effect sizes for the latter were moderate. Global transition judgments also confirmed pre‐/posttreatment improvements in oral health and well‐being. Conclusion: The results provide preliminary evidence of the sensitivity to change of the COHQoL questionnaires when used with children receiving orthodontic treatment. However, the study needs to be repeated in different treatment settings and with a larger sample size in order to confirm the utility of the measure.
Barriers and Triggers to Seeking Help for Potentially Malignant Oral Symptoms: Implications for Interventions
Authors: Scott Suzanne E. , Grunfeld Elizabeth A. , Auyeung Vivian , McGurk Mark
Published: July 2008

Objectives: The detection of oral cancer at an early stage is the most effective means to improve survival and reduce morbidity. However, approximately 30 percent of patients delay seeking help for more than 3 months following the self‐discovery of symptoms of oral cancer. This study aimed to increase our understanding of patient delay to inform the development of interventions to encourage early presentation of oral cancer. Methods: Newly referred patients (n = 57) with potentially malignant oral symptoms were interviewed to determine influences on the timing of their decision to seek help. “Framework analysis” was used to analyze transcripts from semi‐structured interviews. Results: Barriers to seeking help related to beliefs about symptoms, the health care professional (HCP), and an individual's circumstances. The main triggers to seeking help included the symptomatology and the presence of another reason for visiting an HCP. Conclusions: The results are discussed with reference to their implications for interventions aimed at reducing patient delay.
Central European floods 2002: lessons learned in Saxony
Authors: Socher M. , Böhme‐Korn G.
Published: July 2008

In August 2002, Germany and particularly Saxony were hit by a severe flood affecting more than two‐thirds of Saxony's territory. This disastrous flood event gave rise to reconsideration and redirection of flood protection and related disaster management in Saxony. A comprehensive strategic approach was developed. Primarily, any reconstruction and flood protection measure is based on Flood Protection Concepts, which have been developed for all relevant rivers till 2005. In these concepts, more than 1600 individual flood protection measures are proposed and 548 flood risk maps for all communities at risk are available. With a new methodology specially developed for this task, all measures were prioritised, and a Flood Protection Investment Programme with considerable financial resources was put into operation. Furthermore, the new state flood centre ‘Landeshochwasserzentrum’ has been set up and became operational in 2004. It established an advanced full coverage forecast and alert system that has already demonstrated its reliable performance during recent floods.
The Nationalist Discourse in Contemporary Japan: The Role of China and Korea in the Last Decade*
Authors: Akaha Tsuneo
Published: July 2008

This brief paper will critically examine the contentions of Japanese nationalist intellectuals whose stated goal is to restore the Japanese people's pride in their nation through the rehabilitation of patriotism at home, consolidation of a state‐centric view of Japan, and pursuit of a more assertive foreign policy. In particular, what roles do China and Korea play in the nationalists’ arguments? The paper demonstrates that the nationalists engage in a selective use of ideas, events, and institutions of historical significance and that they reconstruct a past Japan in their ideal image and use that image to frame their discourse on the major political and foreign policy challenges facing Japan today. It concludes that the more critical the Chinese and Korean criticisms of Japan are, the more determined the nationalists will be in their rejection of those criticisms and appeals to the general public.
Chinese Nationalism and Sino–Japanese Relations
Authors: Yuan Jing‐Dong
Published: July 2008

Contemporary Chinese nationalism has its roots in the country's nation‐building and identity‐forming movements in the late 19th and early 20th centuries that sought to establish China's place in the community of nations. Today, nationalism in China can be characterized as falling into two major categories. On the one hand, there is nationalism embedded in patriotism with great pride in China's civilization, major achievements, and confidence in the country's future in embracing and meeting the challenges of globalization. On the other hand, there is the sentimental nationalism that reacts to what is perceived as injustice and insult done to China and has a strong victim mentality. The domestic discourse of nationalism can be influenced by government propaganda, intellectual debates, populous display of emotion and repulsion, or a mixture of all three. As China continues to grow in economic power and political influence, how nationalism is handled can have a significant impact on relations with its neighbors and beyond.
China's Water Scarcity and “Hexie Shehui (Harmonious Society)”
Authors: Kim Jih‐Un
Published: July 2008

The “hexie shehui (harmonious society)” is China's new slogan under the Hu Jintao regime, which pursues social and political stability based on sustainable development and people's welfare. However, the country's severe water scarcity and pollution has been a clear fault line in its path to this “harmonious society”. It has threatened people's sustenance; caused grain loss; brought about aquifer depletion and its following land subsidence and seawater penetration; induced water‐seeking migration; and, significantly, triggered conflicts and protests for water. China's political leaders are highly aware of the gravity of the problem and have contrived water‐conservancy programs. However, as the Yellow River Allocation Program, the water consumption quota system/water price increase, and forestation programs demonstrate, the programs have not been implemented effectively due to their institutional flaws as well as the local government's parochialism and corruption.
Investigation of Preferred Orientations in Planar Polycrystals
Authors: Tonks M. R. , Beaudoin A. J. , Schilder F. , Tortorelli D. A.
Published: July 2008

More accurate manufacturing process models come from better understanding of texture evolution and preferred orientations. We investigate the texture evolution in the simplified physical framework of a planar polycrystal with two slip systems used by Prantil et al. (1993, “An Analysis of Texture and Plastic Spin for Planar Polycrystal,” J. Mech. Phys. Solids, 41(8), pp. 1357–1382). In the planar polycrystal, the crystal orientations behave in a manner similar to that of a system of coupled oscillators represented by the Kuramoto model. The crystal plasticity finite element method and the stochastic Taylor model (STM), a stochastic method for mean-field polycrystal plasticity, predict the development of a steady-state texture not shown when employing the Taylor hypothesis. From this analysis, the STM appears to be a useful homogenization method when using representative standard deviations.
A Locally Exact Homogenization Theory for Periodic Microstructures With Isotropic Phases
Authors: Drago Anthony S. , Pindera Marek-Jerzy
Published: July 2008

Elements of the homogenization theory are utilized to develop a new micromechanics approach for unit cells of periodic heterogeneous materials based on locally exact elasticity solutions. The interior inclusion problem is exactly solved by using Fourier series representation of the local displacement field. The exterior unit cell periodic boundary-value problem is tackled by using a new variational principle for this class of nonseparable elasticity problems, which leads to exceptionally fast and well-behaved convergence of the Fourier series coefficients. Closed-form expressions for the homogenized moduli of unidirectionally reinforced heterogeneous materials are obtained in terms of Hill’s strain concentration matrices valid under arbitrary combined loading, which yield homogenized Hooke’s law. Homogenized engineering moduli and local displacement and stress fields of unit cells with offset fibers, which require the use of periodic boundary conditions, are compared to corresponding finite-element results demonstrating excellent correlation.
The Imperfection Sensitivity of Isotropic Two-Dimensional Elastic Lattices
Authors: Symons Digby D. , Fleck Norman A.
Published: July 2008

The imperfection sensitivity of the effective elastic properties is numerically explored for three planar isotropic lattices: fully triangulated, the Kagome grid, and the hexagonal honeycomb. Each lattice comprises rigid-jointed, elastic Euler–Bernoulli beams, which can both stretch and bend. The imperfections are in the form of missing bars, misplaced nodes, and wavy cell walls. Their effect on the macroscopic bulk and shear moduli is numerically investigated by considering a unit cell containing randomly distributed imperfections, and with periodic boundary conditions imposed. The triangulated and Kagome lattices have sufficiently high nodal connectivities that they are stiff, stretching dominated structures in their perfect state. In contrast, the perfect hexagonal honeycomb, with a low nodal connectivity of 3, is stretching dominated under pure hydrostatic loading but is bending dominated when the loading involves a deviatoric component. The high connectivity of the triangulated lattice confers imperfection insensitivity: Its stiffness is relatively insensitive to missing bars or to dispersed nodal positions. In contrast, the moduli of the Kagome lattice are degraded by these imperfections. The bulk modulus of the hexagonal lattice is extremely sensitive to imperfections, whereas the shear modulus is almost unaffected. At any given value of relative density and level of imperfection (in the form of missing bars or dispersed nodal positions), the Kagome lattice has a stiffness intermediate between that of the triangulated lattice and the hexagonal honeycomb. It is argued that the imperfections within the Kagome lattice switch the deformation mode from stretching to a combination of stretching and bending. Cell-wall waviness degrades the moduli of all three lattices where the behavior of the perfect structure is stretching dominated. Since the shear response of the perfect hexagonal honeycomb is by bar bending, the introduction of bar waviness has a negligible effect on the effective shear modulus.
Uniform Stresses Inside an Elliptical Inhomogeneity With an Imperfect Interface in Plane Elasticity
Authors: Wang X. , Pan E. , Sudak L. J.
Published: July 2008

We consider an elliptical inhomogeneity embedded in an infinite isotropic elastic matrix subjected to in-plane deformations under the assumption of remote uniform loading. The inhomogeneity-matrix interface is assumed to be imperfect, which is simulated by the spring-layer model with vanishing thickness. Its behavior is based on the assumption that tractions are continuous but displacements are discontinuous across the interface. We further assume that the same degree of imperfection on the interface is realized in both the normal and tangential directions. We find a form of interface function, which leads to uniform stress field within the elliptical inhomogeneity. The explicit expressions for the uniform stress field within the elliptical inhomogeneity are derived. The obtained results are verified by comparison with existing solutions. The condition under which the internal stress field is not only uniform but also hydrostatic is also presented.
Dynamic
Crack-Tip Stress and Displacement Fields Under Thermomechanical Loading in Functionally Graded
Materials
Authors: Lee Kwang
Ho , Chalivendra Vijaya
Bhaskar , Shukla Arun
Published: July 2008

Thermomechanical stress and displacement fields for a propagating crack in functionally graded materials (FGMs) are developed using displacement potentials and asymptotic analysis. The shear modulus, mass density, and coefficient of thermal expansion of the FGMs are assumed to vary exponentially along the gradation direction. Temperature and heat flux distribution fields are also derived for an exponential variation of thermal conductivity. The mode mixity due to mixed-mode loading conditions around the crack tip is accommodated in the analysis through the superposition of opening and shear modes. Using the asymptotic stress fields, the contours of isochromatics (contours of constant maximum shear stress) are developed and the results are discussed for various crack-tip thermomechanical loading conditions.
Green’s Functions for a Half-Space and Two Half-Spaces Bonded to a Thin Anisotropic Elastic Layer
Authors: Ting T. C. T.
Published: July 2008

The Green’s function for an anisotropic elastic half-space that is bonded to a thin elastic material of different anisotropy subject to a line force and a line dislocation is presented. Also presented is the Green’s function for two different anisotropic elastic half-spaces that are bonded to a thin elastic material of different anisotropy subject to a line force and a line dislocation in one of the half-spaces. The thickness h of the thin layer is assumed to be small compared with a reference length. Thus, instead of finding the solution in the thin layer and imposing the continuity conditions at the interface(s), we derive and apply effective boundary conditions for the interface between the layer and the body that take into account the existence of the layer.
The Buckling of a Swollen Thin Gel Layer Bound to a Compliant Substrate
Authors: Sultan Eric , Boudaoud Arezki
Published: July 2008

Gels are used to design bilayered structures with high residual stresses. The swelling of a thin layer on a compliant substrate leads to compressive stresses. The postbuckling of this layer is investigated experimentally; the wavelengths and amplitudes of the resulting modes are measured. A simplified model with a self-avoiding rod on a Winkler foundation is in semiquantitative agreement with experiments and reproduces the observed cusplike folds.
Special Coordinates Associated With Recursive Forward Dynamics Algorithm for Open Loop Rigid Multibody Systems
Authors: Deepak Sangamesh R. , Ghosal Ashitava
Published: July 2008

The recursive forward dynamics algorithm (RFDA) for a tree structured rigid multibody system has two stages. In the first stage, while going down the tree, certain equations are associated with each node. These equations are decoupled from the equations related to the node’s descendants. We refer them as the equations of RFDA of the node and the current paper derives them in a new way. In the new derivation, associated with each node, we recursively obtain the coordinates, which describe the system consisting of the node and all its descendants. The special property of these coordinates is that a portion of the equations of motion with respect to these coordinates is actually the equations of RFDA associated with the node. We first show the derivation for a two noded system and then extend to a general tree structure. Two examples are used to illustrate the derivation. While the derivation conclusively shows that equations of RFDA are part of equations of motion, it most importantly gives the associated coordinates and the left out portion of the equations of motion. These are significant insights into the RFDA.
Active Absorption of Viscously Damped System With Time Delay
Authors: Ram Yitshak M. , Singh Kumar Vikram
Published: July 2008

In general, it is not possible to obtain total motion absorption of a certain degree of freedom in a harmonically excited damped system by passive control. This paper presents a method of obtaining total absorption in viscously damped system by active control, including time delay, which is unavoidable in digital controlled system. The control is applied on one degree of freedom and the absorption is achieved at another point. This study is carried out by both complex and real analyses. The necessary and sufficient condition for obtaining total absorption is given. Examples demonstrate the various results.
Stiffness Design of Continuum Structures by a Bionics Topology Optimization Method
Authors: Cai Kun , Chen Biao-song , Zhang Hong-wu , Shi Jiao
Published: July 2008

A heuristic approach is presented to solve continuum topology optimization problems with specified constraints, e.g., structural volume constraint and/or displacement constraint(s). The essentials of the present approach are summarized as follows. First, the structure is regarded as a piece of bone and the topology optimization process is viewed as bone remodeling process. Second, a second-rank positive and definite fabric tensor is introduced to express the microstructure and anisotropy of a material point in the design domain. The eigenpairs of the fabric tensor are the design variables of the material point. Third, Wolff’s law, which states that bone microstructure and local stiffness tend to align with the stress principal directions to adapt to its mechanical environment, is used to renew the eigenvectors of the fabric tensor. To update the eigenvalues, an interval of reference strain, which is similar to the concept of dead zone in bone remodeling theory, is suggested. The idea is that, when any one of the absolute values of the principal strains of a material point is out of the current reference interval, the fabric tensor will be changed. On the contrary, if all of the absolute values of the principal strains are in the current reference interval, the fabric tensor remains constant and the material point is in a state of remodeling equilibrium. Finally, the update rule of the reference strain interval is established. When the length of the interval equals zero, the strain energy density in the final structure distributes uniformly. Simultaneously, the volume and the displacement field of the final structure are determined uniquely. Therefore, the update of the reference interval depends on the ratio(s) between the current constraint value(s) and their critical value(s). Parameters, e.g., finite element mesh the initial material and the increments of the eigenvalues of fabric tensors, are studied to reveal their influences on the convergent behavior. Numerical results demonstrate the validity of the method developed.
Effect of Fluctuations in the Brush Conformation on the Interaction Between Polymer Brushes in a Good Solvent
Authors: Shen Yan Xing , Lin Jen Fin
Published: July 2008

This study presents a novel approach for analyzing the interaction between two parallel surfaces grafted with polymer brushes in a good solvent. In the proposed approach, molecular dynamics simulations are performed to establish the mean brush height and the standard deviation of the brush height distribution for a given value of the surface separation. The corresponding probability density function (PDF) of the brush height is then determined and a statistical technique is applied to compute the corresponding interaction free energy per unit area of the grafted substrates. Finally, the Derjaguin approximation is employed to determine the corresponding value of the interaction force between the two surfaces. At relatively high surface grafting density as well as under low to moderate compressions of these two parallel plates, the interdigitation effect of the brushes is quite weak and is not considered in the present study. The results obtained for the interaction free energy and interaction force are compared with those derived using the Alexander and de Gennes (AdG) model [1977, “Adsorption of Chain Molecules With a Polar Head. A Scaling Approach,” J. Phys. (Paris), 38, pp. 983–989, 1985, “Films of Polymer-Solutions,” C. R. Acad. Sci., 300, pp. 839–843] and the Milner, Witten, and Cates (MWC) model [1988, “Theory of the Grafted Polymer Brush,” Macromolecules, 21, pp. 2610–2619], respectively. The value of the normalized interaction free energy computed using the present method is higher than that obtained from the AdG and MWC models at larger surface separations. However, the three sets of results are in good agreement particularly at smaller values of the surface separation. In addition, the results obtained by the current method for the interaction force are found to be in better agreement with the experimental data than those obtained using the AdG or MWC models. The enhanced performance of the proposed method is attributed primarily to the use of an adaptive non-Gaussian PDF of the brush height to model the effects of fluctuations in the brush conformation at different distances from the grafting plane.
Fracture Toughness of Highly Irradiated Pressure Vessel Steels in the Upper Shelf Temperature
Authors: Matsuzawa Hiroshi , Osaki Toru
Published: July 2008

Nine Reactor Pressure Vessel (RPV) Steels and four RPV weld were irradiated up to 1.2 × 1024n/m2 fast neutron fluence (E>1MeV), and their fracture toughness and Charpy impact energy were measured. As chemical compositions, such as Cu, are known to affect the fracture toughness reduction due to neutron exposure, the above steels were fabricated by changing chemical composition widely to cover the chemical composition of the RPV materials of the operating Japanese nuclear power plants. 2.7 mm thick compact specimens were used to measure the upper shelf fracture toughness of highly irradiated materials, and their Charpy upper shelf energy was also measured. By correlating Charpy upper shelf energy to fracture toughness, the upper shelf fracture toughness evaluation formulae for highly irradiated reactor pressure vessel steels were developed. Both compact and V-notched Charpy impact specimens were irradiated in a test reactor. The fast neutron flux above 1MeV was about 5 × 1016n/(m2s). Charpy impact specimens made of Japanese PWR reference material containing 0.09w% Cu were irradiated simultaneously. The upper shelf energy of the reference material up to the medium fluence level showed little difference in the reduction of upper shelf energy to that which had been in the operating plant and which was irradiated to the same fluence. The developed correlation formulae have been adopted in the Japan Electric Association Code as new formulae to predict the fracture toughness in the upper shelf region of reactor pressure vessels. They will be applied to time limited ageing analysis of low upper shelf reactor pressure vessels in Japan, on a concrete technical basis in very high fluence regions.
Rigid/Unyielding Surface Characterization Using Modal Testing Techniques
Authors: Estochen Edwin G.
Published: July 2008

One requirement for impact tests, performed for packaging qualification, is that the target surface or target supporting surface must be “essentially unyielding”. The definition of “essentially unyielding,”, includes the characteristics of being both rigid and unyielding. The unyielding characteristic of a surface is shown without much difficulty by demonstrating limited, local permanent deformation after impact. However, for a surface to be proven rigid, the structural properties that influence the dynamic response must be known and compared to the energy spectrum associated with anticipated impact tests. The methodology and procedure for a cost effective approach using standard modal testing techniques to quickly demonstrate that a surface in essentially unyielding, is described herein.
Bolted Flanged Connection for Critical Engineering Applications
Authors: Efremov Anatoly
Published: July 2008

A novel type of Bolted Flanged Connection based on inverse flexion flange design and bolted fasteners and gasket with cores of shape memory alloy displaying “negative creep effect” is examined. The clamping forces resulting from bolt preload and from interaction of bolts and gasket with rigidly fixed outer end of flange rings inhibit a flange rotation and create a high leak-tight joint which can maintain significant increase of internal pressure under conditions of a variety of operating temperatures relating to critical engineering applications.
High Temperature Rotors: Failure Mechanisms and Remnant Life Assessment
Authors: Zhang Xiaoling
Published: July 2008

This paper presents the common failure mechanisms of high temperature rotors and the engineering approaches to their remnant life prediction. • Rotor bore fatigue crack growth — cracks from original forging defects or induced during long service life may grow under cyclic loading into its critical size causing fast fracture. • Shaft surface fatigue-creep interaction — high tensile residual stress relaxation under high operating temperature causes creep crack initiation. The cracks would then grow under the combination of cyclic loading and high operating temperature. • Remanent creep life at the centre of the rotor is based on the time while accumulated creep strain reaches its threshold level. • Creep rupture could occur at other locations such as the outside surface of the shaft at discs/shaft radii or blade fixings. Finite element method is a powerful tool to analyse stresses, temperature transients, creep strain and reference stress for creep rupture. Fracture mechanics analyses with R5 & R6 approaches were used to estimate the crack initiation and growth rates, the critical crack sizes and the type of the failure. Appropriate Paris law and Norton creep laws were used for fatigue and creep crack growth. Depending on the failure mechanism, a rotor’s remnant life is defined in terms of allowable starts and operating hours.
Extending Pressure Relief Valve Inspection Intervals by Using Statistical Analysis of Proof Test Data
Authors: Gross Robert E. , Harris Stephen P.
Published: July 2008

This paper correlates as-received relief valve test results with current inspection intervals and presents conclusions based on statistical analysis. During the past three year period over 500 used valve proof test records from a site population of 3500 safety relief valves were acquired and reviewed. Collection and analysis of spring-loaded relief valve test data continues with the goal being to increase the test intervals within guidelines, reduce costs, and maintain safety margins. Based on current test intervals of 1–7 years, time in service appears to have a minimal effect on valve performance. Seat material and inlet size are identified as having a statistically significant impact on valve performance. An increase in TP/SP of 1–2% per year was noted for soft seated, small inlet sizes. Photographs of failed valve internals and discussion of failure causes are included.
Stress Intensity Factor Solution for Subsurface Flaw Estimated by Influence Function Method
Authors: Miyazaki Katsumasa , Iwamatsu Fuminori , Nakanishi Shin , Shiratori Masaki
Published: July 2008

The flaw evaluation procedure in ASME Boiler and Pressure Vessel Code Section XI Appendix A is based on the linear elastic fracture mechanics, where the stress intensity factor for the given flaw geometry and applied stress is used to evaluate fatigue crack growth and unstable brittle fracture. The current original procedure for calculation of stress intensity factor for elliptical subsurface crack was based on a linearization method to have conservative estimation for nonlinear stress fields. To improve this current approach, the stress intensity factor solution for subsurface flaw was discussed to allow for the stress variation at the crack location to be represented by a forth order polynomial function. The use of a forth order polynomial fit to represent the actual stress distribution will greatly improve the accuracy of the method for nonlinear stress fields such as those caused by thermal transient loadings and residual stresses caused by weld. The coefficients of stress intensity factor for elliptical subsurface flaw for polynomial fit were estimated by the influence function method. These coefficients were verified by the comparison of stress intensity factor calculated by other similar solutions.