bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic variation in brain‐derived neurotrophic factor and human fear conditioning
Authors: Hajcak G. , Castille C. , Olvet D. M. , Dunning J. P. , Roohi J. , Hatchwell E.
Published: January 2009

Brain‐derived neurotrophic factor (BDNF) has been implicated in hippocampal‐dependent learning processes, and carriers of the Met allele of the Val66Met BDNF genotype are characterized by reduced hippocampal structure and function. Recent nonhuman animal work suggests that BDNF is also crucial for amygdala‐dependent associative learning. The present study sought to examine fear conditioning as a function of the BDNF polymorphism. Fifty‐seven participants were genotyped for the BDNF polymorphism and took part in a differential‐conditioning paradigm. Participants were shocked following a particular conditioned stimulus (CS+) and were also presented with stimuli that ranged in perceptual similarity to the CS+ (20, 40 or 60% smaller or larger than the CS+). The eye blink component of the startle response was measured to quantify fear conditioning; post‐task shock likelihood ratings for each stimulus were also obtained. All participants reported that shock likelihood varied with perceptual similarity to the CS+ and showed potentiated startle in response to CS ± 20% stimuli. However, only the Val/Val group had potentiated startle responses to the CS+. Met allele carrying individuals were characterized by deficient fear conditioning – evidenced by an attenuated startle response to CS+ stimuli. Variation in the BDNF genotype appears related to abnormal fear conditioning, consistent with nonhuman animal work on the importance of BDNF in amygdala‐dependent associative learning. The relation between genetic variation in BDNF and amygdala‐dependent associative learning deficits is discussed in terms of potential mechanisms of risk for psychopathology.
Erythema multiforme majus (Fuchs syndrome) associated with Mycoplasma pneumoniae infection in two patients
Authors: Havliza Katrin , Jakob Antje , Rompel Rainer
Published: January 2009

In Germany Fuchs syndrome is used to describe a variant of erythema multiforme majus which mainly involves the mucosal surfaces. As the skin may be completely unaffected, it is an under‐recognized diagnosis and often difficult to confirm. Clinical features involve erythema, erosions and ulcerations of the oral mucosa. In most cases there is severe conjunctivitis and sometimes the genital mucosa is involved. Most cases of Fuchs syndrome are triggered by infections; herpes simplex virus and Mycoplasma pneumoniae are the most common causes. We describe two women presenting with Fuchs syndrome after respiratory illness caused by Mycoplasma pneumoniae.
Perforating folliculitis, angioedema, hand‐foot syndrome – multiple cutaneous side effects in a patient treated with sorafenib
Authors: Wolber Carola , Udvardi Astrid , Tatzreiter Georg , Schneeberger Achim , Volc‐Platzer Beatrix
Published: January 2009

A patient with clear cell renal cell carcinoma was treated with sorafenib, a multikinase inhibitor, which induced a variety of cutaneous side effects. In addition to xerosis, he developed angioedema (AE), hand‐foot syndrome (HFS) and perforating folliculitis (PF). The latter three occurred in a dose‐dependent manner. AE was observed at the recommended daily dose of 800 mg. Dose reduction to 400 mg prevented its recurrence. At this dose level, the patient exhibited HFS, which cleared upon further reduction of the dose. While receiving 200 mg, the patient developed PF. To the best of our knowledge, this is the first description of a case of PF during treatment with sorafenib.
Cultural and Contextual Influences on Parenting in Mexican American Families
Authors: White Rebecca M. B. , Roosa Mark W. , Weaver Scott R. , Nair Rajni L.
Published: January 2009

Family stress theory can explain associations between contextual stressors and parenting. The theory, however, has not been tested among Mexican Americans or expanded to include cultural‐contextual risks. This study examined associations between neighborhood, economic, and acculturative stressors and parenting behaviors in a sample of 570 two‐parent Mexican American families. Results support the negative impact of economic stress on parenting through parental depressive symptoms. Neighborhood stress influenced fathers’ depressive symptoms and parenting, but not mothers’. The effects of acculturative stress were inconsistent. Results suggest that contextual stressors common to Mexican American families impact parenting behaviors through parental depression.
Marital Dissolution Among Interracial Couples
Authors: Zhang Yuanting , Van Hook Jennifer
Published: January 2009

Increases in interracial marriage have been interpreted as reflecting reduced social distance among racial and ethnic groups, but little is known about the stability of interracial marriages. Using six panels of Survey of Income and Program Participation (N= 23,139 married couples), we found that interracial marriages are less stable than endogamous marriages, but these findings did not hold up consistently. After controlling for couple characteristics, the risk of divorce or separation among interracial couples was similar to the more‐divorce‐prone origin group. Although marital dissolution was found to be strongly associated with race or ethnicity, the results failed to provide evidence that interracial marriage per se is associated with an elevated risk of marital dissolution.
Do Sons or Daughters Give More Money to Parents in Urban China?
Authors: Xie Yu , Zhu Haiyan
Published: January 2009

The patriarchal structure of the traditional Chinese family suggests that sons, more than daughters, provide financial support to elderly parents. The norm of receiving support in old age primarily from sons, however, may have been undermined by dramatic demographic, economic, and cultural changes occurring over the last several decades in China, especially in urban areas. We examine gender differences in adult children’s financial support to parents using a recent data set (“Study of Family Life in Urban China”) collected in 1999 (N= 1,801). The results show that married daughters, especially those living with parents, provide more financial support to parents than married sons do. This significant gender difference can be primarily explained by daughters’ resources, such as education and income.
Hypoxia downregulates farnesoid X receptor via a hypoxia‐inducible factor‐independent but p38 mitogen‐activated protein kinase‐dependent pathway
Authors: Fujino Tomofumi , Murakami Kaori , Ozawa Issei , Minegishi Yoshie , Kashimura Ryo , Akita Toshihiro , Saitou Susumu , Atsumi Takehisa , Sato Takashi , Ando Ken , Hara Shuntaro , Kikugawa Kiyomi , Hayakawa Makio
Published: January 2009

Farnesoid X receptor (FXR), a member of the nuclear receptor superfamily, has been shown to play pivotal roles in bile acid homeostasis by regulating the biosynthesis, conjugation, secretion and absorption of bile acids. Accumulating data suggest that FXR signaling is involved in the pathogenesis of liver and metabolic disorders. Here we show that FXR expression is significantly suppressed in HepG2 cells exposed to hypoxia. Concomitantly, the expression of the bile salt export pump, known as an FXR target gene product and responsible for the excretion of bile acids from the liver, is also decreased under hypoxia. Overexpression of hypoxia‐inducible factor (HIF)‐1α does not mimic the suppressive effect of hypoxia on FXR expression. Furthermore, simultaneous knockdown of HIF‐1α, HIF‐2α and HIF‐3α fails to restore the FXR expression level under hypoxia, indicating that HIF is not involved in hypoxia‐evoked FXR downregulation. Instead, we demonstrate that p38 mitogen‐activated protein kinase is an indispensable factor for FXR downregulation under hypoxia. Thus, we propose a novel liver disorder model in which two signaling molecules, p38 mitogen‐activated protein kinase and FXR, may contribute to the linkage of two pathogenic conditions, i.e. ischemia, a condition accompanying hypoxia, and cholestasis, a condition with intrahepatic accumulation of cytotoxic bile acids.
Institutional Review Boards: From Bane to Benefit
Authors: Fiske Susan T.
Published: January 2009

Institutional review boards (IRBs) are primarily prevention-focused, avoiding damage to human subjects and averting ethical infractions, thereby protecting participants, researchers, and universities. Yet, the cost of prevention focus is simply avoiding negative outcomes and is enacted through control, risk-aversion, security, detail-orientation, reactivity, anxiety, avoidance, punishment, negative possibilities, and seizing on a single dominant solution. These endanger the research enterprise. An alternative promotion focus is more advantageous as it seeks positive outcomes and thus facilitating research, which is the IRB s second duty. This alternative guides recruiting and training of staff, panel, and researchers; orienting to and reinforcing promotion norms; creating well-known, transparent, responsive, and efficient processes; and understanding the IRB's boundaries. Promotion balances prevention to make IRBs support research and protect subjects.
Evidence-Based Ethical Problem Solving (EBEPS)
Authors: Sieber Joan E.
Published: January 2009

Although there is usually agreement about the ethical principles that should govern human research, there may be little agreement on how those principles should be interpreted into research procedures in some instances. Empirical research on ethical issues can often elucidate ways to improve on existing research practices and resolve debates with one's institutional review board.
Why Can't We Be More Idiographic in Our Research?
Authors: Barlow David H. , Nock Matthew K.
Published: January 2009

Most psychological scientists make inferences about the relations among variables of interest by comparing aggregated data from groups of individuals. Although this method is unarguably a useful one that will continue to yield scientific advances, important limitations exist regarding the efficiency and flexibility of such designs, as well as with the generality of obtained results. Idiographic research strategies, which focus on the intensive study of individual organisms over time, offer a proficient and flexible alternative to group comparison designs; however, they are rarely taught in graduate training programs and are seldom used by psychological scientists. We highlight some of the unique strengths of idiographic methods, such as single case experimental designs, and suggest that psychological science will progress most efficiently with an increased use of such methods in both laboratory and clinical settings.
Applying the Psychology of Science to the Science of Psychology: Can Psychologists Use Psychological Science to Enhance Psychology as a Science?
Authors: Simonton Dean Keith
Published: January 2009

Added to the already tremendous diversity of subdisciplines of psychological science is the psychology of science. Although research on the psychology of science began in 1874, the field has seen a substantial expansion of activity in recent years. One particular subset of this research literature has special importance: namely, inquiries into the psychology of doing great science. These investigations may be assigned into four groups: cognitive, differential, developmental, and social. Each of these deal with critical questions that can, if answered, contribute directly to the improvement of psychology as a science. Potential applications include (a) the identification of scientific talent in psychology, (b) the education of future investigators in psychological science, and (c) the evaluation of psychology's progress as a scientific endeavor.
What Are the Brain Mechanisms on Which Psychological Processes Are Based?
Authors: Cacioppo John T. , Decety Jean
Published: January 2009

That the human brain is the organ of the mind is not in dispute, but we know remarkably little about the brain mechanisms underlying the mind. What are the functional structures and computational processes of the human brain that subserve cognition, emotion, and behavior? Given the complexity of the human brain, progress in understanding the functional organization and structure of the human brain depends on sophisticated theoretical specifications of the psychological representations and processes that differentiate two or more comparison conditions. Psychological scientists, therefore, are well positioned to lead the search for brain mechanisms underlying psychological processes. Doing so constitutes an expansion of the purview of psychological science beyond a science of behavior, and beyond a science of the mind, to include a science of the brain. Such an expansion of the mission of psychological science has implications for the infrastructure and training needs of the discipline.
Learning for Life: An Ecological Approach to Pedagogical Research
Authors: Daniel David B. , Poole Debra A.
Published: January 2009

The trend to convert laboratory findings on the conditions associated with optimal memory into recommendations for teaching strategies and learning aids will harm students if findings fail to generalize to students' usual learning environments. Moreover, it is likely that pedagogies function differently for students with different degrees of background knowledge, time, and interest in the subject matter; that some support activities will prevent students from honing their ability learn from narrative material without guided learning; and that an overuse of learning aids will tax students' ability to use them effectively. We contrast two approaches to developing pedagogy—memory first and pedagogical ecology—and explain how the human factors approach of pedagogical ecology could be a more satisfying model for the scholarship of teaching and learning.
Solving Social Problems Like a Psychologist
Authors: Walton Gregory M. , Dweck Carol S.
Published: January 2009

We suggest that psychologists can play a larger role in the solution of important social problems. Psychology brings two important qualities to the study of social problems: attention to psychological process and rigorous methodology. Our key task is to define social problems in part as psychological problems, and to conduct rigorous research that tests novel psychological solutions. Examples of research that has taken this path—research on race differences in academic performance, on the training of executive function and intelligence, and on the provision of socially constructive default decisions—are provided. We argue that addressing social problems can enrich our science by connecting psychologists to interdisciplinary teams and by providing contexts in which to demonstrate, in striking ways, the value of a psychological approach.
Impact of Racism on Ethnic Minority Mental Health
Authors: Okazaki Sumie
Published: January 2009

A problem in ethnic minority mental health that can be solved in the foreseeable future is understanding how subtle and covert forms of racism affect psychological health of racial minorities. Although scientific psychology has generated a large body of literature on racial prejudice, stereotypes, intergroup attitudes, and racial bias and their often implicit and automatic nature, relatively little is known about the effects of these subtle racial bias on minority individuals. Following a selective review of recent developments in experimental psychology and multicultural psychology, I suggest some promising approaches and opportunities for future integration that would advance the field.
A New Approach to Reducing Disorder and Improving Well-Being
Authors: Huppert Felicia A.
Published: January 2009

Psychological science has usually approached the treatment of disorder through research on individual combinations of risk and protective factors (including life experiences, thinking styles, behaviors, social relationships and genes) and the application of interventions that focus on improvements in the individual. However, we can do better than this. Not only should we be aiming to enhance well-being rather than merely reducing disorder, but we should also be doing so for the majority of people rather than the few who have a disorder. In this article, I focus on the mental health spectrum and make the case for a broad population-based approach. I argue that a very small shift in the population mean of the underlying symptoms or risk factors can do more to enhance well-being and reduce disorder than would any amount of intervention with individuals who need help. Examples from research on alcohol abuse and psychological distress are presented to illustrate the value of a population-based approach.
Publishing in Scientific Journals: We're Not Just Talking to Ourselves Anymore
Authors: Taylor Shelley E.
Published: January 2009

Increasingly, psychological research is part of the integrative science that spans multiple disciplines, but variable publication standards undermine some of the integrative progress that might otherwise be made. Word limits for articles, norms for shorter reviews (which would improve turnaround time), electronic availability, and appropriate marketing of research will bring psychology closer to the central role it could play in integrative science.
Masked Reviews Are Not Fairer Reviews
Authors: Newcombe Nora S. , Bouton Mark E.
Published: January 2009

Many people believe that reviewers are less likely to produce unfair and biased reviews when they do not know the identity of the authors. However, there is surprisingly little evidence of such bias, there is little evidence that masked review is effective in addressing bias, and masked review has potential costs and drawbacks to the research community. More empirical work on the existence and nature of bias is needed.
Publishing in the Psychological Sciences: Enhancing Journal Impact While Decreasing Author Fatigue
Authors: Park Denise C.
Published: January 2009

The publication process in the psychological sciences is unduly tedious and would benefit from the adoption of a publishing model typical of the neurosciences and basic sciences. The author argues that such a change would result in higher impact publications in the psychological sciences and would also conserve the time of busy scientists.
Problems, Pitfalls, and Promise in the Peer-Review Process: Commentary on Trafimow & Rice (2009)
Authors: Cooper M. Lynne
Published: January 2009

In their critique of the peer-review process, Trafimow and Rice (2009, this issue) dramatize a number of ways in which the review process can go awry. On the whole, I agree that the issues highlighted by the authors are indeed problems worthy of careful consideration. However, I fear that their treatment of these issues could send mixed and misleading messages to would-be reviewers about what constitutes proper reviewing behavior, in part because the authors had little to say on this topic. In the present commentary, I attempt to address this omission by discussing qualities of a good review and by distinguishing several responsibilities in the peer-review process that lie uniquely with the editor and the author. Finally, I identify three general strategies for improving the peer-review process that center on providing better, more formalized training of reviewers; increasing accountability of both editors and reviewers; and reducing burden on the peerreview system.
Optimization of Cardiac Resynchronization Therapy: Echocardiographic vs Semiautomatic Device Algorithms
Authors: Anselmino Matteo , Antolini Marina , Amellone Claudia , Piovano Elena , Massa Riccardo , Trevi GianPaolo
Published: January 2009

Large evidence supports the importance of individualized optimization of cardiac resynchronization therapy in patients with congestive heart failure. The aim of this study was to compare a recently developed intracardiac electrogram (IEGM)–based method with the Doppler echocardiographic (ECHO)–based method to calculate optimal atrioventricular (AV) and interventricular (VV) delays. Ten male patients implanted with a St Jude Medical resynchronization device received AV and VV delay assessment with both the IEGM and the ECHO‐based methods. Estimates of the optimal AV and VV delays assessed by the 2 tested methods proved highly comparable. No difference emerged between the IEGM (126.8±22.7) and the ECHO (127.3±19.8) AV delay values (P=.987). The VV delay suggested by ECHO was highly significantly correlated with the delays calculated by the IEGM method (35±27.6 vs 21.31±24.31; r2=0.78; P<.001). These preliminary data support the evidence that an IEGM based cardiac resynchronization optimization method may be as reliable as a complete ECHO assessment.
Determination of Left Ventricular Systolic Dyssynchrony by Tissue Doppler Echocardiography in Patients With Nonischemic Dilated Cardiomyopathy
Authors: Karaahmet Tansu , Tigen Kursat , Mutlu Bulent , Cevik Cihan , Kahveci Gokhan , Basaran Yelda
Published: January 2009

The authors investigated the left ventricular systolic dyssynchrony (LVSD) parameters in nonischemic dilated cardiomyopathy (DCM) by tissue Doppler echocardiography. A total of 56 DCM patients with normal sinus rhythm and 15 controls were recruited. The patients were subgrouped according to QRS duration (QRSd): QRSd ≤120 milliseconds (group I) and QRSd >120 milliseconds (group II). Ts was defined as the duration from the initiation of QRS to the peak systolic velocity. Patients with DCM had longer intraventricular delay time (IVDT) (101.8 vs 47.4 milliseconds; P<.0001) and standard deviation of Ts (Ts‐SD) values (34.9 vs 17.8 milliseconds; P<.0001) compared with controls. There was no difference in IVDT and Ts‐SD between the 2 DCM subgroups. The cut‐off value for LVSD was 60 milliseconds for IVDT and 25 milliseconds for Ts‐SD. The prevalence of LVSD in DCM patients was found to be 78% in group I and 94% in group II. LVSD is common in DCM, regardless of QRSd.
Atrial Fibrillation and Heart Failure
Authors: Larned Joshua M , Raja Laskar S.
Published: January 2009

Atrial fibrillation (AF) is the most common arrhythmia in congestive heart failure (HF) and indicates a worse prognosis. AF increases HF symptoms and increases in prevalence with increasing New York Heart Association class. AF also interferes with the ideal management of HF. Across all HF etiologies, AF may be a marker of disease severity. Yet, controversies exist regarding whether strategies to restore and maintain sinus rhythm can improve outcomes in HF. It is also unclear what the optimal strategy is to suppress the ventricular response to AF in patients with HF. As HF incidence and prevalence continue to rise, the authors sought to reinvestigate current literature that relates AF to HF and examine the impact of therapy on HF and/or AF. The authors performed a literature review using a MEDLINE search from 1966 to the present and included existing literature based on their strength of evidence.
Do Comorbid Psychiatric Disorders Contribute to the Pathogenesis of Tako‐Tsubo Syndrome? A Review of Pathogenesis
Authors: Nguyen Sun B. , Cevik Cihan , Otahbachi Mohammad , Kumar Ashwani , Jenkins Leigh Ann , Nugent Kenneth
Published: January 2009

Patients with tako‐tsubo cardiomyopathy have unusual characteristics, including a disproportionate occurrence in postmenopausal women and a strong association with mental and physical stress. These patients present with chest pain, abnormal electrocardiographic findings, and myocardial enzyme leaks. They appear to have acute coronary syndrome but have normal epicardial coronary vessels and reversible left ventricular dysfunction. High circulating levels of catecholamines likely cause this syndrome through direct injury of myocardial cells. The frequent occurrence in postmenopausal women has not been explained. This association might reflect changes in autonomic control of the cardiovascular system and in baroreceptor sensitivity in postmenopausal women. Women in this age group also have a high frequency of both depression and anxiety. These 2 psychiatric diagnoses are associated with episodic symptoms, including acute panic attacks, which can be associated with catecholamine release in the heart. Therefore, tako‐tsubo cardiomyopathy may occur in postmenopausal women as a consequence of comorbid psychiatric diagnoses and normal age‐related changes in autonomic control of the cardiovascular system. This hypothesis warrants prospective case‐control studies.
SYNTHESIS: Cancer research meets evolutionary biology
Authors: Pepper John W. , Scott Findlay C. , Kassen Rees , Spencer Sabrina L. , Maley Carlo C.
Published: January 2009

There is increasing evidence that Darwin’s theory of evolution by natural selection provides insights into the etiology and treatment of cancer. On a microscopic scale, neoplastic cells meet the conditions for evolution by Darwinian selection: cell reproduction with heritable variability that affects cell survival and replication. This suggests that, like other areas of biological and biomedical research, Darwinian theory can provide a general framework for understanding many aspects of cancer, including problems of great clinical importance. With the availability of raw molecular data increasing rapidly, this theory may provide guidance in translating data into understanding and progress. Several conceptual and analytical tools from evolutionary biology can be applied to cancer biology. Two clinical problems may benefit most from the application of Darwinian theory: neoplastic progression and acquired therapeutic resistance. The Darwinian theory of cancer has especially profound implications for drug development, both in terms of explaining past difficulties, and pointing the way toward new approaches. Because cancer involves complex evolutionary processes, research should incorporate both tractable (simplified) experimental systems, and also longitudinal observational studies of the evolutionary dynamics of cancer in laboratory animals and in human patients. Cancer biology will require new tools to control the evolution of neoplastic cells.
Pathophysiology and puzzles of the volume‐sensitive outwardly rectifying anion channel
Authors: Okada Yasunobu , Sato Kaori , Numata Tomohiro
Published: January 2009

Cell swelling activates or upregulates a number of anion channels. Of the volume‐activated or ‐regulated anion channels (VAACs or VRACs), the volume‐sensitive outwardly rectifying anion channel (VSOR) is most prominently activated and ubiquitously expressed. This channel is known to be involved in a variety of physiological processes including cell volume regulation, cell proliferation, differentiation and cell migration as well as cell turnover involving apoptosis. Recent studies have shown that VSOR activity is also involved in a number of pathophysiological processes including the acquisition of cisplatin resistance by cancer cells, ischaemia–reperfusion‐induced death of cardiomyocytes and hippocampal neurons, glial necrosis under lactacidosis as well as neuronal necrosis under excitotoxicity. Moreover, VSOR serves as the pathway for glutamate release from astrocytes under ischaemic conditions and when stimulated by bradykinin, an initial mediator of inflammation. So far, many signalling molecules including the EGF receptor, PI3K, Src, PLCγ and Rho/Rho kinase have been implicated in the regulation of VSOR activity. However, our pharmacological studies suggest that these signals are not essential components of the swelling‐induced VSOR activation mechanism even though some of these signals may play permissive or modulatory roles. Molecular identification of VSOR is required to address the question of how cells sense volume expansion and activate VSOR.
A Correlation Analysis of Cooling-Induced Temperature Changes
Authors: Yang Tiebao , Hu Henry , Chen Xiang , Chu Yeou-li , Cheng Patrick
Published: January 2009

Proper temperature control is essential for producing superior quality components and yielding high production rates in high temperature manufacturing processes. Due to the closure of machine tools such as casting dies during production, it is usually very difficult to monitor their local surface temperatures without destructively inserting thermal sensors into them. However, the measurement of cooling water temperature at the coolant outlet is relatively unproblematic. This work demonstrates that there is a correlation between these two temperatures. As an example, the effect of the local surface temperature of a casting die on the cooling water outlet temperature is analyzed from a laboratory die casting process simulator. Based on the system identification theory, a control-oriented linear time-invariant model has been developed, which correlates the local die temperature to the cooling water outlet temperature. The model enables the prediction of the local die temperature with the measurements of the cooling water temperature. Thus, it provides an alternative approach other than the destructive sensing method to acquire the local die temperatures, and the model could be applied to design a real-time temperature control system for die cooling process.
Three-Dimensional Identification of Semi-Elliptical Crack on the Back Surface by Means of Direct-Current Electrical Potential Difference Method With Multiple-Probe Sensor (PVP2006-ICPVT-11-93359)
Authors: Tada Naoya , Funakoshi Akira
Published: January 2009

Cracks are popular defects initiated in structural components and their accurate evaluation is very important to assure the reliability of various plants. The direct-current electrical potential difference method is known as one of the most effective methods for the evaluation of the cracks. In this paper, a method of three-dimensional identification of a semi-elliptical crack existing on the back surface of a conductive plate by the direct-current electrical potential difference method with a multiple-probe sensor is proposed. The geometrical condition of the crack was specified by six parameters, the surface and inward angles of the crack plane, θsur and θin, the length and depth of the crack, c and a, and the two-dimensional location of the crack center, (yc,zc), on the back surface. The identification was carried out based on the distribution of electrical potential difference on the surface of the plate measured with a sensor composed of grid-arranged multiple probes called the “multiple-probe sensor.” As an approximate cracked body and a quick analysis method were used, a number of repeated electrical potential field analyses necessary for the identification of the crack became possible within a practical time. The validity of the method was numerically confirmed by carrying out the identification based on the result of the finite element analysis. The proposed method could be extended to the online monitoring of a semi-elliptical crack initiated on the inner surface of tubular components by means of the multiple-probe sensor placed on the outer surface.
Multiaxial Fatigue of 16MnR Steel
Authors: Gao Zengliang , Zhao Tianwen , Wang Xiaogui , Jiang Yanyao
Published: January 2009

Uniaxial, torsion, and axial-torsion fatigue experiments were conducted on a pressure vessel steel, 16MnR, in ambient air. The uniaxial experiments were conducted using solid cylindrical specimens. Axial-torsion experiments employed thin-walled tubular specimens subjected to proportional and nonproportional loading. The true fracture stress and strain were obtained by testing solid shafts under monotonic torsion. Experimental results reveal that the material under investigation does not display significant nonproportional hardening. The material was found to display shear cracking under pure shear loading but tensile cracking under tension-compression loading. Two critical plane multiaxial fatigue criteria, namely, the Fatemi–Socie criterion and the Jiang criterion, were evaluated based on the experimental results. The Fatemi–Socie criterion combines the maximum shear strain amplitude with a consideration of the normal stress on the critical plane. The Jiang criterion makes use of the plastic strain energy on a material plane as the major contributor to the fatigue damage. Both criteria were found to correlate well with the experiments in terms of fatigue life. The predicted cracking directions by the criteria were less satisfactory when comparing with the experimentally observed cracking behavior under different loading conditions.
Dynamic Strength Estimates for a High-Strength Experimental Steel
Authors: Torres K. L. , Clements H. A. , Jones S. E. , Dilmore M. , Martin B.
Published: January 2009

For several years, the Air Force has been engaged in the development of high velocity air to surface missiles to defeat hard targets, such as concrete, sand, and soil. The objective is to replace larger, high mass weapons with smaller, more versatile projectiles that can achieve the same goals. The reduction of mass requires that the impact velocity be increased to meet the performance requirements. This has presented researchers with several challenges. First, the steel must be such that it survives the initial shock at impact. Second, because the travel distance in the target is long, the material must resist friction and wear, which could erode the projectile nose, thereby degrading performance. The purpose of this paper is to present the results of dynamic testing of an experimental high-strength steel, also called Eglin steel. Using a one-dimensional model for the Taylor cylinder test, the constitutive behavior of the steel as a function of strain and strain rate can be assessed through a strain rate of roughly 105∕s. This behavior is consistent with that required for successful modeling of the response of a penetrator casing in the ultra-ordinance velocity range.
A Review of the Effects of Coolant Environments on the Fatigue Life of LWR Structural Materials
Authors: Chopra O. K. , Shack W. J.
Published: January 2009

The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code specifies design curves for the fatigue life of structural materials in nuclear power plants. However, the effects of light water reactor (LWR) coolant environments were not explicitly considered in the development of the design curves. The existing fatigue-strain-versus-life (ε-N) data indicate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. Under certain environmental and loading conditions, fatigue lives in water relative to those in air can be a factor of 15 lower for austenitic stainless steels and a factor of ≈30 lower for carbon and low-alloy steels. This paper reviews the current technical basis for the understanding of the fatigue of piping and pressure vessel steels in LWR environments. The existing fatigue ε-N data have been evaluated to identify the various material, environmental, and loading parameters that influence fatigue crack initiation and to establish the effects of key parameters on the fatigue life of these steels. Statistical models are presented for estimating fatigue life as a function of material, loading, and environmental conditions. An environmental fatigue correction factor for incorporating the effects of LWR environments into ASME Code fatigue evaluations is described. This paper also presents a critical review of the ASME Code fatigue design margins of 2 on stress (or strain) and 20 on life and assesses the possible conservatism in the current choice of design margins.
Ratcheting of Stainless Steel 304 Under Multiaxial Nonproportional Loading
Authors: Kim Kwang S. , Jiao Rong , Chen Xu , Sakane Masao
Published: January 2009

Multiaxial ratcheting is often simulated by use of nonlinear kinematic hardening models, while in reality materials show cyclic hardening/softening and additional hardening under nonproportional loading. The effect of isotropic hardening on ratcheting needs to be addressed in simulation. In this study, ratcheting tests are conducted on stainless steel 304 under uniaxial, torsional, and combined axial-torsional loading. The ratcheting strain is predicted based on the constitutive theory that incorporates a modified Ohno–Wang kinematic hardening rule and Tanaka’s isotropic hardening model. The results show that the main features of the stress-strain response can be simulated with the constitutive model. Ratcheting strain under axial mean stress depends highly on the loading path and load level, and the degree of cyclic changes in shear stress under torsional strain control is not as influential. The torsional ratcheting strain under mean shear stress with (or without) fully reversed axial strain cycling is found close to the axial ratcheting strain under equivalent mean stress with (or without) torsional strain cycling. In all, the experimental and predicted ratcheting strains for nonproportional paths are found in decent correlation. However, overprediction still prevails for some loading paths, and ratcheting rates deviate considerably from experimental values.
Evaluation of Microstructures and Creep Damages in the HAZ of P91 Steel Weldment
Authors: Tabuchi Masaaki , Hongo Hiromichi , Li Yongkui , Watanabe Takashi , Takahashi Yukio
Published: January 2009

The creep strength of welded joints in high Cr steels decreases due to the formation of Type IV creep damage in heat-affected zones (HAZs) during long-term use at high temperatures. This paper aims to elucidate the processes and mechanisms of Type IV creep damage using Mod.9Cr–1Mo (ASME Grade 91) steel weldments. Long-term creep tests for base metal, simulated fine-grained HAZ, and welded joints were conducted at 550°C, 600°C, and 650°C. Furthermore, creep tests of thick welded joint specimens were interrupted at 0.1, 0.2, 0.5, 0.7, 0.8, and 0.9 of rupture life and damage distributions were measured quantitatively. It was found that creep voids were initiated at an early stage of life inside the specimen thickness and coalesced to form cracks at a later stage of life. Creep damage was observed mostly at 25% below the surface of the plate. Experimental creep damage distributions were compared with computed versions using finite element method and damage mechanics analysis. Both multi-axial stress state and strain concentration in fine-grained HAZ appear to influence the formation and distribution of creep voids.
Optimal Design of Measurement Point Layout for Workpiece Localization
Authors: Zhu LiMin , Luo HongGen , Ding Han
Published: January 2009

This paper presents a methodology for the optimal design of the measurement point layout for 3D workpiece localization in the presence of part surface errors and measurement errors. A number of frame-invariant norms of the infinitesimal rigid body displacement, two of which give Riemann metrics on the Euclidean group, are defined to quantify the localization accuracy required by manufacturing processes. Then, two types of indices, both frame invariant and scale invariant, are derived to characterize the sensitivities of the accuracy measures to the sampling errors at the measurement points. With a dense set of discrete points on the workpiece datum surfaces predefined as candidates for measurement, planning of probing points to accurately recover part location is modeled as a combinatorial problem focusing on minimizing the accuracy sensitivity index. It is shown that if the number of measurement points is large enough, there is no need to optimize their positions, and that if the systematic error component of the sampled geometric errors is not negligible as compared with the random error component, addition of measurement points offers no guarantee of a smaller upper bound of the localization error. A heuristic floating forward search algorithm is employed to efficiently find a near-optimal solution. Two relevant problems of sensor placement optimization for geometric imperfection diagnosis and fixture fault diagnosis are also briefly revisited in the same framework. Examples are given to illustrate the effectiveness of the proposed design criteria and algorithm.
An Analysis of Polymer Coated Metal Rod Extrusion
Authors: Wang Jyhwen , Shah Ritesh , Huang Yu-Hsuan , Chang Der-Form
Published: January 2009

Deformable coated materials hold promises for numerous new technologies. In this research, extrusion of polymer coated metal rods was investigated. Analytical models based on upper bound method were developed to evaluate axisymmetric conical die extrusion of precoated materials. The rigid-plastic boundaries were optimized to obtain minimum extrusion power and to predict coating failure. From the models, the critical extrusion die angle can be derived. The analytical results agreed well with the results from the finite element simulation. The developed models can be used for extrusion die design and process analysis and can lead to lower cost and environmental friendly manufacturing technologies.
Nanofluids: Synthesis, Heat Conduction, and Extension
Authors: Wang Liqiu , Wei Xiaohao
Published: January 2009

We synthesize eight kinds of nanofluids with controllable microstructures by a chemical solution method (CSM) and develop a theory of macroscale heat conduction in nanofluids. By the CSM, we can easily vary and manipulate nanofluid microstructures through adjusting synthesis parameters. Our theory shows that heat conduction in nanofluids is of a dual-phase-lagging type instead of the postulated and commonly used Fourier heat conduction. Due to the coupled conduction of the two phases, thermal waves and possibly resonance may appear in nanofluid heat conduction. Such waves and resonance are responsible for the conductivity enhancement. Our theory also generalizes nanofluids into thermal-wave fluids in which heat conduction can support thermal waves. We emulsify olive oil into distilled water to form a new type of thermal-wave fluids that can support much stronger thermal waves and resonance than all reported nanofluids, and consequently extraordinary water conductivity enhancement (up to 153.3%) by adding some olive oil that has a much lower conductivity than water.
Relativistic Molecular Dynamics Simulations of Laser Ablation Process on the Xenon Solid
Authors: Wang Yun-Che , Chen Jing-Wen , Liao Lun-De , Lin Hong-Chang , Hwang Chi-Chuan
Published: January 2009

The phenomena of Coulomb explosion require the consideration of special relativity due to the involvement of high energy electrons or ions. It is known that laser ablation processes at high laser intensities may lead to the Coulomb explosion, and their released energy is in the regime of kEV to MeV. In contrast to conventional molecular dynamics (MD) simulations, we adopt the three-dimensional relativistic molecular dynamics (RMD) method to consider the effects of special relativity in the conventional MD simulation for charged particles in strong electromagnetic fields. Furthermore, we develop a Coulomb force scheme, combined with the Lennard-Jones potential, to calculate interactions between charged particles, and adopt a Verlet list scheme to compute the interactions between each particle. The energy transfer from the laser pulses to the solid surface is not directly simulated. Instead, we directly assign ion charges to the surface atoms that are illuminated by the laser. By introducing the Coulomb potential into the Lennard-Jones potential, we are able to mimic the laser energy being dumped into the xenon (Xe) solid, and track the motion of each Xe atom. In other words, the laser intensity is simulated by using the repulsive forces from the Coulomb potential. Both nonrelativistic and relativistic simulations are performed, and the RMD method provides more realistic results, in particular, when high-intensity laser is used. In addition, it is found that the damage depth does not increase with repeated laser ablation when the pulse frequency is comparable to the duration of the pulse. Furthermore, we report the time evolution of energy propagation in space in the laser ablation process. The temporal-spatial distribution of energy indirectly indicates the temperature evolution on the surface of the Xe solid under intense laser illumination.
Residual Stress in an Autofrettaged Tube Taking Bauschinger Effect as a Function of the Prior Plastic Strain
Authors: Huang Xiaoping , Moan Torgeir
Published: January 2009

Autofrettage is a practical method for increasing the elastic carrying capacity and the fatigue life of thick-walled cylinders such as cannon and high-pressure tubular reactor. Many analytical and numerical solutions for determining the residual stress distribution in an autofrettaged tube have been reported. It is still difficult to model the Bauchinger effect, which is dependent on the prior plasticity in an analytical solution. The reduced Young’s modulus during unloading affects residual stress distribution. However, until now this effect has not been considered in any analytical model. In this paper, an autofrettage analytical solution considering Young’s modulus and the reverse yield stress dependent on the prior plasticity, based on the actual tensile-compressive curve of the material and the von Mises yield criterion, has been proposed. New model incorporates the Bauschinger effect factor and the unloading modulus variation as a function of prior plastic strain, and hence of the radius. Thereafter it assumes a fixed nonlinear unloading profile. The comparison of predicted residual stress distribution by the present solution with that of fixed unloading curve model, and test results shows that the present solution gives accurate prediction of residual stress distribution of an autofrettaged tube. This analytical procedure for the cylinder permits an excellent representation of various pressure vessel steels.
Cast-In Hypereutectic Aluminum Liners for Engine-Blocks
Authors: Morales Fernando , Talamantes-Silva José , Valtierra Salvador , Pérez-Unzueta Alberto J. , Colás Rafael
Published: January 2009

A series of experimental trials was carried out to study the metallic bond produced when hypereutectic aluminum liners are cast-in hypoeutectic aluminum engine-blocks. The samples were cast in a rig that reproduces the conditions encountered during production of engine-blocks made of a type 319 aluminum alloy. The surface roughness of the liners was modified by sand blasting before casting. Some of the liners were cast after coating their surface with an amorphous carbon layer (soot) to study its effect on the metallic bond. The samples were sectioned and prepared for their examination and testing. It was found that soot does not allow the development of a metallic bond between liner and body and that the force required to remove the liners depended on such a bond; in any case, the force required to remove cast-in liners, even without bonding, was higher than that needed for removing gray iron press-in liners.
Prediction of Fully Plastic Collapse Stresses for Pipes With Two Circumferential Flaws
Authors: Hasegawa Kunio , Saito Koichi , Iwamatsu Fuminori , Miyazaki Katsumasa
Published: January 2009

Fully plastic collapse stress for a single circumferential flaw on a pipe is evaluated by the limit load criteria in accordance with the JSME Code S NA-1-2004 and the ASME Code Section XI. However, multiple flaws such as stress corrosion cracking are frequently detected in the same circumferential cross section in a pipe. If the distance between adjacent flaws is short, the two flaws are combined as a single flaw in compliance with combination rules. If the two flaws separated by a large distance, it is not required to combine two flaws. However, there is no evaluation method for two separated flaws in a pipe in the JSME and ASME Codes. Plastic collapse stresses for pipes with two symmetrical circumferential flaws based on net-stress approach had been proposed by one of the authors. Bending tests were performed on Type 304 stainless steel pipes with two symmetrical circumferential flaws. Consequently, it was shown that the proposed method can predict well the plastic collapse stresses for pipes with two flaws. In addition, it is also shown that this method is appropriate to use in fitness-for-service procedures, and higher plastic collapse stresses are expected, compared with current prediction methods for pipes with two flaws.