bluuebunny/crossref_metadata_2025 huggingface dataset:
Pacemaker lead infection and related bacteraemia caused by normal and small colony variant phenotypes of Bacillus licheniformis
Authors: Idelevich Evgeny A. , Pogoda Christian A. , Ballhausen Britta , Wüllenweber Jörg , Eckardt Lars , Baumgartner Helmut , Waltenberger Johannes , Peters Georg , Becker Karsten
Published: March 2013

Here, we report what we believe to be the first case of bacteraemia with small colony variants ofBacillus licheniformisrelated to a pacemaker lead infection byB. licheniformisdisplaying the normal phenotype. Arbitrarily primed PCR analysis showed a clonal strain. The infection was cured after the removal of the infected device.
Surface-layer (S-layer) of human and animal Clostridium difficile strains and their behaviour in adherence to epithelial cells and intestinal colonization
Authors: Spigaglia Patrizia , Barketi-Klai Amira , Collignon Anne , Mastrantonio Paola , Barbanti Fabrizio , Rupnik Maja , Janezic Sandra , Kansau Imad
Published: March 2013

Clostridium difficile is a frequent cause of severe, recurrent post-antibiotic diarrhoea and pseudomembranous colitis. The surface layer (S-layer) is the predominant outer surface component of C. difficile which is involved in pathogen–host interactions critical to pathogenesis. In this study, we characterized the S-layer protein A (SlpA) of animal and human strains belonging to different PCR-ribotypes (PR) and compared the in vitro adherence and in vivo colonization properties of strains showing different SlpA variants. Since each SlpA variant has been recently associated with an S-layer cassette, we were able to deduce the cassette for each of our strains. In this study, an identity of 99–100 % was found among the SlpA of isolates belonging to PR 012, 014/020, 045 and 078. One exception was the SlpA of a poultry isolate, PR 014/020, which showed 99 % identity with that of strain 0160, another PR 014/020 which contains an S-layer cassette 6. Interestingly, this cassette has also been found in a PR 018 strain, an emerging virulent type currently predominant in Italy. Five other SlpA variants (v014/020a–e) were identified in strains PR 014/020. In vitro adherence assays and in vivo colonization experiments were performed on five PR 014/020 strains: human 1064 (v014/020e), human 4684/08 (v014/020b), human IT1106 (v078a), poultry P30 (v014/020d) and poultry PB90 (v014/020b) strains. Adhesion assays indicate that C. difficile strains vary in their capacity to adhere to cells in culture and that adhesion seems to be independent of the SlpA variant. Colonization properties were assessed in vivo using a dixenic mouse model of colonization. The kinetics of faecal shedding and caecal colonization were similar when human 4684/08 (v014/020b) strain was compared with human 1064 (v014/020e) and poultry PB90 (v014/020b) strain. In contrast, poultry P30 (v014/020d) strain outcompeted both human 4684/08 (v014/020b) and IT1106 (v078a) strains and its adherence to caeca at day 7 was significantly higher. The peculiar characteristics of C. difficile P30 seem to advantage it in colonizing the intestinal mice niche, increasing its ability to compete and adapt. The results obtained underline the need of an increased attention to the genetic evolution of C. difficile to prevent and limit the consequences of the emergence of increasingly virulent strains.
High frequency of carbapenem-resistant Acinetobacter baumannii in patients with diabetes mellitus in Saudi Arabia
Authors: Alsultan A. A. , Evans B. A. , Elsayed E. A. , Al-Thawadi S. I. , Al-Taher A. Y. , Amyes S. G. B. , Al-Dughaym A. M. , Hamouda A.
Published: March 2013

Carbapenem-resistantAcinetobacter baumanniiis becoming increasingly prevalent in patients with diabetes mellitus in the Middle East. We examined the relationship of these bacteria and their resistance mechanisms to the diabetic disease status of patients in Saudi Arabia. Susceptibilities of 271 isolates to carbapenems, tigecycline and colistin were determined, followed by detection of carbapenemase genes. AblaVIMgene was detected in ~95 % of isolates;blaOXA-23andblaOXA-40genes were also prevalent. Diabetic patients were significantly more likely to carry carbapenem-resistant isolates. Carbapenem-resistantA. baumanniiis a serious problem in diabetic patients, and molecular detection of resistance mechanisms in these isolates is required.
Yokenella regensburgei infection in India mimicking enteric fever
Authors: Jain Sarika , Gaind Rajni , Gupta Kunj Bihari , Dawar Reetika , Kumar Deepak , Paul Premila , Sardana Raman , Deb Manorama
Published: March 2013

Yokenella regensburgei is an opportunistic human pathogen of the Enterobacteriaceae family rarely reported to cause human infections. Here, we present a case report of Y. regensburgei bacteraemia from India clinically resembling enteric fever in an apparently immunocompetent paediatric patient.
Robust cellular reprogramming occurs spontaneously during liver regeneration
Authors: Yanger Kilangsungla , Zong Yiwei , Maggs Lara R. , Shapira Suzanne N. , Maddipati Ravi , Aiello Nicole M. , Thung Swan N. , Wells Rebecca G. , Greenbaum Linda E. , Stanger Ben Z.
Published: March 2013

Cellular reprogramming—the ability to interconvert distinct cell types with defined factors—is transforming the field of regenerative medicine. However, this phenomenon has rarely been observed in vivo without exogenous factors. Here, we report that activation of Notch, a signaling pathway that mediates lineage segregation during liver development, is sufficient to reprogram hepatocytes into biliary epithelial cells (BECs). Moreover, using lineage tracing, we show that hepatocytes undergo widespread hepatocyte-to-BEC reprogramming following injuries that provoke a biliary response, a process requiring Notch. These results provide direct evidence that mammalian regeneration prompts extensive and dramatic changes in cellular identity under injury conditions.
Widespread and extensive lengthening of 3′ UTRs in the mammalian brain
Authors: Miura Pedro , Shenker Sol , Andreu-Agullo Celia , Westholm Jakub O. , Lai Eric C.
Published: March 2013

Remarkable advances in techniques for gene expression profiling have radically changed our knowledge of the transcriptome. Recently, the mammalian brain was reported to express many long intergenic noncoding (lincRNAs) from loci downstream from protein-coding genes. Our experimental tests failed to validate specific accumulation of lincRNA transcripts, and instead revealed strongly distal 3′ UTRs generated by alternative cleavage and polyadenylation (APA). With this perspective in mind, we analyzed deep mammalian RNA-seq data using conservative criteria, and identified 2035 mouse and 1847 human genes that utilize substantially distal novel 3′ UTRs. Each of these extends at least 500 bases past the most distal 3′ termini available in Ensembl v65, and collectively they add 6.6 Mb and 5.1 Mb to the mRNA space of mouse and human, respectively. Extensive Northern analyses validated stable accumulation of distal APA isoforms, including transcripts bearing exceptionally long 3′ UTRs (many >10 kb and some >18 kb in length). The Northern data further illustrate that the extensions we annotated were not due to unprocessed transcriptional run-off events. Global tissue comparisons revealed that APA events yielding these extensions were most prevalent in the mouse and human brain. Finally, these extensions collectively contain thousands of conserved miRNA binding sites, and these are strongly enriched for many well-studied neural miRNAs. Altogether, these new 3′ UTR annotations greatly expand the scope of post-transcriptional regulatory networks in mammals, and have particular impact on the central nervous system.
A magical moment in research translation: strategies for providing high intensity bimanual therapy
Authors: Novak Iona
Published: March 2013

This commentary is on the original article by Green et al. on pages 527–533 of this issue.
Preterm birth and behaviour problems in infants and preschool‐age children: a review of the recent literature
Authors: Arpi Elena , Ferrari Fabrizio
Published: March 2013

The behaviour problems of children born preterm at school age are well known, but there have been few studies on the behaviour problems of preterm‐born infants during infancy and at preschool age. Fourteen cohort studies published in PubMed and PsycINFO between 2000 and 2012 were reviewed with a focus on the type, occurrence, comorbidity, stability, prediction, perinatal, social, and relational risk factors for behaviour problems of preterm‐born children in infancy (0–2y) and at preschool age (3–5y). The relational risk factor was considered in an additional four papers. Very‐preterm, very‐low‐birthweight, and moderately‐preterm children, in both age groups, show more behaviour problems than term‐born comparison children even after perinatal and social risk factors and cognitive performance have been controlled for. Poor social/interactive skills, poor behavioural and emotional self‐regulation, emotional difficulties, and reduced attention are the most common behaviour problems. Behaviour problems in infancy are predictive of later behaviour problems and they should be included in follow‐up programmes.
Amputations and foot ulcers in patients newly diagnosed with Type 2 diabetes mellitus and observed for 19 years. The role of age, gender and co‐morbidity
Authors: Bruun C. , Siersma V. , Guassora A. D. , Holstein P. , de Fine Olivarius N.
Published: March 2013

Aims

To determine the prevalence of foot ulcers and the incidence of amputations in patients with Type 2 diabetes observed for 19 years after diagnosis. We investigated the role of gender, age and co‐morbidities.

Methods

From the Diabetes Care in General Practice study, 1381 patients were included and examined at diabetes diagnosis, at 6 years and at 14 years after diagnosis. Register‐based follow‐up was for 19 years. Foot ulcers and amputations were related to gender, age and co‐morbidities by odds and hazard ratios from logistic and Cox regression models, respectively.

Results

The incidence of any amputation and major amputation was 400 (95% CI 307–512) and 279 (95% CI 203–375) per 100 000 patient‐years, respectively. At the three observation points, the foot ulcer prevalences were 2.76% (95% CI 1.89–3.63), 2.93% (95% CI 1.86–4.00) and 4.96% (95% CI 3.10–6.82). Multivariate analyses showed associations between foot ulcers and peripheral neuropathy, peripheral arterial disease, male gender, retinopathy and myocardial infarction. After multivariate adjustment, significant predictors (hazard ratio; 95% CI) of any amputation were peripheral neuropathy (hazard ratio 2.09; 95% CI 1.19–3.69), peripheral arterial disease (hazard ratio 3.43; 95% CI 1.65–7.12), microalbuminuria (hazard ratio 2.11; 95% CI 1.21–3.67), retinopathy (hazard ratio 6.42; 95% CI 2.59–15.90), impaired vision (hazard ratio 6.92; 95% CI 2.35–20.38) and male gender (hazard ratio 2.40; 95% CI 1.31–4.41). For women, the risk of amputation increased with age, but for men the risk was higher when diagnosed with diabetes at a younger age.

Conclusions

Despite improved treatment regimens, the incidence of amputations is still high in this population‐based patient sample. Men diagnosed with diabetes before age 65 years and patients with diabetes‐related co‐morbidities are at particularly high risk of foot ulcers and amputations.
Associations between pigment epithelium‐derived factor, insulin resistance and high density lipoprotein
Authors: Pek S. , Tavintharan S. , Woon K. , Niyati J. , Lim S. C. , Sum C. F.
Published: March 2013

Aims

To measure serum pigment epithelium‐derived factor in control subjects with normal fasting glucose, and in subjects with impaired fasting glucose and those with newly diagnosed Type 2 diabetes, before treatment initiation, and to measure pigment epithelium‐derived factor prospectively in patients being treated with HDL‐raising therapy, niacin.

Methods

We enrolled 89 individuals attending an institutional health screen. Biochemical indices including lipids, homeostasis model assessment‐insulin resistance, high‐sensitivity C‐reactive protein and pigment epithelium‐derived factor were analysed in fasting blood. To validate the association between HDL and pigment epithelium‐derived factor, we analysed samples from a separate study cohort with low HDL, followed up for 12‐weeks while on niacin treatment. Secreted pigment epithelium‐derived factor from 3T3‐L1 adipocytes, after HDL treatment (24‐h), was measured using Western blot analysis.

Results

Mean (± sd) serum pigment epithelium‐derived factor was significantly higher in subjects with impaired fasting glucose [13.99 (± 3.06) μg/ml] and Type 2 diabetes [12.94 (± 2.61)] μg/ml, compared with control subjects [11.83 (± 2.85) μg/ml (P = 0.014)]. In multivariate analyses, serum pigment epithelium‐derived factor concentration was associated with BMI (β = 0.32, 0.007), homeostasis model assessment‐insulin resistance (β = 0.33, P = 0.01) and HDL (β =  −0.24, P = 0.05), after adjustment for age, gender and high‐sensitivity C‐reactive protein. In the niacin study, on‐treatment HDL was an independent determinant of pigment epithelium‐derived factor (β =  −0.439, P = 0.033), after adjusting for age, homeostasis model assessment‐insulin resistance and treatment. Adipocytes treated with HDL were found to have reduced pigment epithelium‐derived factor secretion [24.8% (50 μg/ml), 28.4% (100 μg/ml) HDL; P < 0.05)], compared with the control samples.

Conclusion

Serum pigment epithelium‐derived factor is positively associated with homeostasis model assessment‐insulin resistance and negatively associated with HDL. Further studies are needed to understand the mechanism of low HDL and raised pigment epithelium‐derived factor and to determine if they are causally related to the pathobiology of insulin resistance.
Objective measurements of activity patterns in people with newly diagnosed Type 2 diabetes demonstrate a sedentary lifestyle
Authors: Cichosz S. L. , Fleischer J. , Hoeyem P. , Laugesen E. , Poulsen P. L. , Christiansen J. S. , Ejskjær N. , Hansen T. K.
Published: March 2013

Aims

To evaluate physical activity in people with newly diagnosed Type 2 diabetes using objective measures.

Methods

We analysed data from a study aimed at assessing carotid femoral pulse wave velocity in which a piezoelectric accelerometer was worn by 100 people with newly diagnosed Type 2 diabetes and by 100 age‐ and sex‐matched control subjects. Differences in physical activity patterns were investigated.

Results

Compared with the control group, the people with Type 2 diabetes spent significantly more time engaged in sedentary or lower level activities during the day, with a mean (sd) time of 926 (44) vs 898 (70) min, P < 0.001). This difference remained significant after correction for differences in BMI between the two groups.

Conclusions

Using objective measurements, our findings demonstrate that people with newly diagnosed Type 2 diabetes have a more sedentary lifestyle compared with well‐matched controls.
Hemorrhagic transformation in patients with acute ischaemic stroke and an indication for anticoagulation
Authors: Marsh E. B. , Llinas R. H. , Hillis A. E. , Gottesman R. F.
Published: March 2013

Background and purpose

Intracerebral hemorrhage (ICH) can occur in patients following acute ischaemic stroke in the form of hemorrhagic transformation, and results in significant long‐term morbidity and mortality. Anticoagulation theoretically increases risk. We evaluated stroke patients with an indication for anticoagulation to determine the factors associated with hemorrhagic transformation.

Methods

Three‐hundred and forty‐five patients with ICD‐9 codes indicating: (i) acute ischaemic stroke; and (ii) an indication for anticoagulation were screened. One‐hundred and twenty‐three met inclusion criteria. Data were collected retrospectively. Neuroimaging was reviewed for infarct volume and evidence of ICH. Hemorrhages were classified as: hemorrhagic conversion (petechiae) versus intracerebral hematoma (a space occupying lesion); symptomatic versus asymptomatic. Using multivariable logistic regression, we determined the hypothesized factors associated with intracerebral bleeding.

Results

Age [odds ratio (OR) = 1.50 per 10‐year increment, 95% confidence interval (CI) 1.07–2.08], infarct volume (OR = 1.10 per 10 ccs, 95% CI 1.06–1.18) and worsening category of renal impairment by estimated glomerular filtration rate (eGFR; OR = 1.95, 95% CI 1.04–3.66) were predictors of hemorrhagic transformation. Ninety‐ nine out of 123 patients were anticoagulated. Hemorrhage rates of patients on and off anticoagulation did not differ (25.3% vs. 20.8%; P = 0.79); however, all intracerebral hematomas (n = 7) and symptomatic bleeds (n = 8) occurred in the anticoagulated group.

Conclusions

The risk of hemorrhagic transformation in patients with acute ischaemic stroke and an indication for anticoagulation is multifactorial, and most closely associated with an individual's age, infarct volume and eGFR.
Assessing Gains in Language Proficiency, Cross‐Cultural Competence, and Regional Awareness During Study Abroad: A Preliminary Study
Authors: Watson Jeffrey R. , Siska Peter , Wolfel Richard L.
Published: March 2013

As a critical part of the internationalization movement in college curricula, study abroad initiatives are becoming more and more popular and the need to assess their outcomes more and more evident. While numerous studies have investigated the language gain associated with study abroad, researchers are also beginning to look at potential gains in the areas of cultural and regional competence. This study presents a theoretical background for a three‐tiered model for assessing student outcomes during study abroad in three domains—language proficiency, cross‐cultural competence, and regional awareness—and presents the quantitative data gathered from the implementation of this model. Results show the feasibility of assessing these outcomes in a holistic manner through formal assessment instruments and participant coaching pre‐ and post‐immersion.
Examining Modeling Approaches for the Rainfall‐Runoff Process in Wildfire‐Affected Watersheds: Using San Dimas Experimental Forest
Authors: Chen Li , Berli Markus , Chief Karletta
Published: March 2013

Wildfire can significantly change watershed hydrological processes resulting in increased risks for flooding, erosion, and debris flow. The goal of this study was to evaluate the predictive capability of hydrological models in estimating post‐fire runoff using data from the San Dimas Experimental Forest (SDEF), San Dimas, California. Four methods were chosen representing different types of post‐fire runoff prediction methods, including a Rule of Thumb, Modified Rational Method (MODRAT), HEC‐HMS Curve Number, and KINematic Runoff and EROSion Model 2 (KINEROS2). Results showed that simple, empirical peak flow models performed acceptably if calibrated correctly. However, these models do not reflect hydrological mechanisms and may not be applicable for predictions outside the area where they were calibrated. For pre‐fire conditions, the Curve Number approach implemented in HEC‐HMS provided more accurate results than KINEROS2, whereas for post‐fire conditions, the opposite was observed. Such a trend may imply fundamental changes from pre‐ to post‐fire hydrology. Analysis suggests that the runoff generation mechanism in the watershed may have temporarily changed due to fire effects from saturation‐excess runoff or subsurface storm dominated complex mechanisms to an infiltration‐excess dominated mechanism. Infiltration modeling using the Hydrus‐1D model supports this inference. Results of this study indicate that physically‐based approaches may better reflect this trend and have the potential to provide consistent and satisfactory prediction.
Quality Evaluation of Steel, Aluminum, and Road Material Recycled from End‐of‐Life Urban Buildings in Japan in Terms of Total Material Requirement
Authors: Yamasue Eiji , Minamino Ryota , Tanikawa Hiroki , Daigo Ichiro , Okumura Hideyuki , Ishihara Keiichi N. , Brunner Paul H.
Published: March 2013

In this study we introduce the concept of total material requirement (TMR) to quantify the quality of materials from end‐of‐life buildings. The TMRs for the recycling of materials (urban ore TMR [UO‐TMR]) from four types of Japanese buildings ( Japanese traditional wooden structure [ JTWS], wooden frame with walls structure [ WFS ], reinforced‐concrete structure [RCS], and steel‐based structure [SS]) have been estimated and the trade‐off between the increase in function of recycled materials such as steel made from scrap and the additional inputs of energy and materials required to create the increase in function were evaluated. Steel made from scrap, aluminum made from scrap, and road material are assumed to be recycled from steel products, aluminum products, and aggregate and cement concrete in the buildings, respectively. Case study analyses were carried out to determine the effect of recycling only aboveground materials compared to recycling both aboveground and subsurface materials. Also, the effect of varying the recycling rate of wooden demolition debris is determined.

The UO‐TMRs of steel made from scrap range from 4.7 kilograms per kilogram (kg/kg) to 18.2 kg/kg. Urban tailings (unrecycled components) account for the greatest proportion of the UO‐TMR of steel made from scrap, and the next largest contributor is the recycling process. In the case of aluminum made from scrap, the UO‐TMRs range from 22 to 196 kg/kg, with the contribution of urban tailings generally dominant, and the second largest contributor being on‐site demolition and shredding. The UO‐TMRs of recycled road material range from 1.04 to 1.16 kg/kg and are similar for different recycling cases and types of buildings.
Producer Responsibility Organizations Development and Operations
Authors: Mayers Kieren , Butler Scott
Published: March 2013

Extended producer responsibility (EPR) regulations are now in effect in 27 European Union member states and are applicable to up to 100 million tonnes of waste packaging, batteries, automobiles, and electrical and electronic products annually. This article investigates the implementation of EPR through a case study of European Recycling Platform (ERP) UK Ltd., the UK arm of one of the largest producer responsibility organizations (PROs) in Europe, recycling more than 1.5 million tonnes of waste electrical and electronic equipment to date.

Previous research is extremely limited on the detailed operations of PROs. This case is presented as an example illustrating typical operational challenges PROs face in implementing EPR, such as how PROs gain an understanding of the waste management infrastructure and legislation in each country, collect sufficient volumes of waste using cost‐effective arrangements, and maintain uninterrupted collection, treatment, and recycling services. The case study provides new insights and context on the practical implementation of EPR regulations relevant for both policy makers and researchers.
The nanoscale mineralogy of Fe,Ni sulfides in pristine and metamorphosed CM and CM/CI‐like chondrites: Tapping a petrogenetic record
Authors: Harries Dennis , Langenhorst Falko
Published: March 2013

We have sampled sulfide grains from one pristine CM2 chondrite (Yamato [Y‐] 791198), one thermally metamorphosed CM2 chondrite (Y‐793321), and two anomalous, metamorphosed CM/CI‐like chondrites (Y‐86720 and Belgica [B‐] 7904) by the focused ion beam (FIB) technique and studied them by analytical transmission electron microscopy (TEM). Our study aims at exploring the potential of sulfide assemblages and microstructures to decipher processes and conditions of chondrite petrogenesis. Complex exsolution textures of pyrrhotite (crystallographic NC‐type with N ≈ 6), troilite, and pentlandite occur in grains of Y‐791198 and Y‐793321. Additionally, polycrystalline 4C‐pyrrhotite‐pentlandite‐magnetite aggregates occur in Y‐791198, pointing to diverse conditions of gas–solid interactions in the solar nebula. Coarser exsolution textures of Y‐793321 grains indicate higher long‐term average temperatures in the <100 °C range compared to Y‐791198 and other CM chondrites. Sulfide mineralogy of Y‐86720 and B‐7904 is dominated by aggregates of pure troilite and metal, indicating metamorphic equilibration at sulfur fugacities (fS2) of the iron‐troilite buffer. Absence of magnetite in equilibrium with sulfide and metal in Y‐86720 indicates higher peak temperatures compared with B‐7904, in which coexistence of troilite, metal, and magnetite constrains metamorphic temperature to less than 570 °C. NC‐pyrrhotite occurs in both meteorites as nm‐wide rims on troilite grains and, together with frequent anhydrite, indicates a retrograde metamorphic stage at higher fS2 slightly above the fayalite‐magnetite‐quartz‐pyrrhotite buffer. Fine‐grained troilite‐olivine intergrowths in both meteorites suggest the pre‐metamorphic presence of tochilinite‐serpentine interlayer phases, pointing to mineralogical CM affinity. Pseudomorphs after euhedral pyrrhotite crystals in Y‐86720 in turn suggest CI affinity as do previously published O isotopic data of both meteorites.
Fundamental Mechanics of Walking of Unanchored Flat-Bottom Cylindrical Shell Model Tanks Subjected to Horizontal Harmonic Base Excitation
Authors: Taniguchi Tomoyo , Segawa Toru
Published: March 2013

Assuming very large slide displacement subsequent to tank rock motion to be a possible scenario of tank walk motion, fundamental mechanics of the walk motion of unanchored flat-bottom cylindrical shell model tanks subjected to horizontal base excitation is examined. First, employing a 3DOF model consisting of a set of two masses connected by flexible columns, equations of motion are derived through a variational approach. The interaction among the translational motion of a harmonic oscillator consisting of the upper mass and the flexible columns, the rock motion of the 3DOF model and the slide motion of it is thoroughly studied. Comparison of the experimental results and their predictions demonstrate applicability of the proposed analysis. A reduction in nominal friction force accompanying the rock motion that plays a primary role in causing the very large slide displacement is also pointed out. Next, drawing an analogy between the mechanics of the walk motion of the 3DOF model and that of an unanchored flat-bottom cylindrical shell model tank, equations of motion for the tank walk motion are derived. Shaker table test and time domain analysis are conducted, employing a model tank whose bottom plate concentrically uplifts for readily evaluating fluid masses contributing to the tank rock motion. Comparison of the experimental and analytical results of the slide displacement and the rotational angle corroborates the applicability of the proposed analysis.
Effect of Helix Angle on the Stress Intensity Factor of a Cracked Threaded Bolt
Authors: Kumar S. Suresh , Prakash Raghu V.
Published: March 2013

The fracture behavior of a crack in a threaded bolt depends on the stress intensity factor (SIF). Available SIF solutions have approximated the threaded bolt as a circular groove, thus, the SIF predominantly corresponds to the opening mode, mode-I. As a thread in a bolt has a helix angle, the crack propagates under mixed mode conditions (opening, sliding and tearing), esp. when the crack sizes are small. This paper presents the results of SIF solutions for a part-through crack emanating from a Metric threaded bolt. A 3D finite element model with preexisting flaws was generated to calculate the SIF values along the crack front. Crack aspect ratios in the range of (0.2 < (a/c) < 1) and crack depth ratios in the range of (0.1 < (a/d) < 0.5) (where “a” is crack length, “c” is semi major axis of ellipse and “d” is minor diameter of the bolt) were considered along the crack plane for the SIF estimation. The SIF values at the midregion decreases with an increase in aspect ratio (a/c), and SIF increases when the crack depth ratio (a/d) increases in the midregion. Close to the free edges, higher SIF values was observed for crack depth and aspect ratios ranging between 0.2 and 0.6 compared to midregion. In the crack surface region, up to a crack depth ratio of 0.25, significant influence of mode-II and mode-III fracture was noted for shallow cracks (a/c < 0.2). Significant influence of mode-II and mode-III fracture was observed for semicircular cracks (a/c = 1) beyond the crack depth ratio of 0.3.
Determination of Rewetting Velocity During Jet Impingement Cooling of a Hot Surface
Authors: Chitranjan Agrawal  , Kumar Ravi , Gupta Akhilesh , Chatterjee Barun
Published: March 2013

An experimental investigation has been carried out to study the cooling of a hot horizontal stainless steel surface of 0.25 mm thickness, which has 800 ± 10 °C initial temperature. A round water jet of 22 ± 1 °C temperature was injected over the hot surface through a straight tubes type nozzle of 2.5 mm diameter and 250 mm length. The experiments were performed for the jet exit to target surface spacing in a range of 4–16 times of jet diameter and jet Reynolds number in a range of 5000–24,000. The rewetting velocity during transient cooling of hot surface was determined with the help of time variant surface temperature data and with the captured thermal images of the hot surface as well. The effect of Reynolds number, Re, jet exit to surface spacing, z/d, on the rewetting velocity has been determined for the different downstream spatial locations. A correlation has also been developed to determine the rewetting velocity, which predicts 75% of experimental data within an error band of ±10%.
Deterministic Formulation of the Effect of Stress Intensity Factor on PWSCC of Ni-Base Alloys and Weld Metals
Authors: Lu Zhanpeng , Shoji Tetsuo , Xue He , Fu Chaoyang
Published: March 2013

The fundamental correlations such as crack growth rate (CGR) versus K for primary water stress corrosion cracking (PWSCC) of nickel-base alloys in simulated pressurized water reactor environments are quantified with the theoretical model based on the combination of crack tip mechanics and oxidation kinetics. Materials reliability program (MRP) proposed a CGR disposition curve in a report MRP 55 for PWSCC of thick-section Alloy 600 materials. This deterministic CGR equation has been adopted by Section XI Nonmandatory Appendix O of the ASME Boiler and Pressure Code for flaw evaluation. MRP also proposed a CGR disposition curve in a report MRP 115 for PWSCC of Alloy 82/182/132 weld metals. Stress intensity factor (K), temperature and thermal activation energy are included in both MRP 55 and MRP 115 reports. Both MRP 55 and MRP 115 are engineering-based. The results of mechanism-based modeling are compared with the screened experimental data for typical PWSCC systems of nickel-base alloys and the consistence is observed.
A Comparative Evaluation of Fatigue and Fracture Characteristics of Structural Components of Liquefied Natural Gas Carrier Insulation System
Authors: Su Kim Hyeon , Sung Chun Min , Myung Lee Jae , Hyun Kim Myung
Published: March 2013

This study examined the fatigue strength and fracture toughness of the structural components of membrane type liquefied natural gas carrier (LNGC) insulation systems, such as reinforced poly-urethane foam (R-PUF, insulation material) and 304 L stainless steel (STS 304 L, Primary barrier membrane), at both ambient and cryogenic temperatures. The fatigue strength of the LNGC insulation system was compared with that of low density R-PUF (130 kg/m3) and high density R-PUF (210 kg/m3). The fracture toughness of R-PUF and STS 304 L was investigated in terms of the density effect of R-PUF and the difference in the nickel composition of STS 304 L, STS 304 L (10.2%Ni) versus STS 304 L (9.4%Ni) at both ambient and cryogenic temperatures. In this study, the high density R-PUF (210 kg/m3) and STS 304 L (9.4%Ni) were proposed to improve the structural strength of the LNGC insulation system and reduce the cost. The fracture toughness was characterized in terms of the critical strain energy release rate (GIC) in the context of linear elastic fracture mechanics (LEFM). The geometries of the fracture toughness test used were the center-cracked tension (CCT) and double-edge-cracked tension (DECT) specimens according to ASTM STP381 standard.
Crack in Corrosion Defect Assessment in Transmission Pipelines
Authors: Hosseini A. , Cronin D. , Plumtree A.
Published: March 2013

Cracks may occur coincident with corrosion representing a new hybrid defect in gas and oil pipelines known as crack in corrosion (CIC) that is not directly addressed in the current codes or assessment methods. Hence, there is a need to provide an assessment of CIC and evaluate the line integrity, as well as identify the requirements for defect repair or line hydrotest. An experimental investigation was undertaken to evaluate the collapse pressures of lines containing corrosion, cracks, or (CIC) defects in a typical line pipe (API 5L Grade X52, 508 mm diameter, 5.7 mm wall thickness). The mechanical properties of the pipe were measured using tensile, Charpy, and J-testing for use in applying evaluation criteria. Rupture tests were undertaken on end-capped sections containing uniform depth, finite length corrosion, cracks, or CIC defects. Failure occurred by plastic collapse and ductile tearing for the corrosion defects, cracks, and CIC geometries tested. For the corrosion defects, the corroded pipe strength (CPS) method provided the most accurate results (13% conservative on average). The API 579 (level 3 failure assessment diagram (FAD), method D) provided the least conservative collapse pressure predictions for the cracks with an average error of 20%. The CIC collapse pressures were bounded by those of a long corrosion groove (upper bound) and a long crack (lower bound), with collapse dominated by the crack when the crack depth was significant. Application of API 579 to the CIC provided collapse pressure predictions that were 18% conservative. Sixteen rupture tests were successfully completed investigating the failure behavior of longitudinally oriented corrosion, crack, and CIC. The pipe material was characterized and these properties were used to predict the collapse pressure of the defects using current methods. Existing methods for corrosion (CPS) and cracks (API 579, level 3, method D) gave conservative collapse pressure predictions. The collapse pressures for the CIC were bounded by those of a long corrosion groove and a long crack, with collapse dominated by the crack when the crack depth was significant. CIC failure behavior was determined by the crack to corrosion depth ratio, total defect depth and its profile. The results showed that the failure pressures for CIC were reduced when their equivalent depths were similar to those of corrosion and using crack evaluation techniques provided an approximate collapse pressure.
Evaluation of Thermal Contact Resistance at the Interface of Dissimilar Materials
Authors: Fukuoka Toshimichi , Nomura Masataka
Published: March 2013

When jointed portions of structures and machines are subjected to thermal loads, various problems and troubles occur due to the difference in thermal expansions between mating parts. In order to accurately analyze thermal and mechanical behaviors of the joints, the effect of thermal contact resistance must be taken into account. In this paper, thermal contact coefficient, which is the reciprocal of thermal contact resistance, at the interface of dissimilar materials is quantitatively measured by infrared thermography. The target materials are common engineering materials such as carbon steel, stainless steel and aluminum alloy. It has been shown in the previous papers that there exists a significant directional effect in thermal contact coefficients when the mating surface is composed of different materials. That is, thermal contact coefficient has a larger value when the heat flows from the material with lower thermal conductivity to the one with higher thermal conductivity. The effects of contact pressure and surface roughness on the coefficient are also evaluated in this work. Using the measured data, an empirical equation to estimate thermal contact coefficient is proposed, for the purpose of engineering applications, which correlates closely with the experimental data.
Welding Residual Stress in a Large Diameter Nuclear Reactor Pressure Vessel Nozzle
Authors: Zhang Tao , Brust Frederick W. , Wilkowski Gery , Xu Heqin , Betervide Alfredo A. , Mazzantini Oscar
Published: March 2013

The Atucha II nuclear power plant is a pressurized heavy water reactor (PHWR) being constructed in Argentina. The original plant was designed by Kraftwerk Union (KWU) in the 1970’s using the German methodology of break preclusion. The plant construction was halted for several decades, but a recent need for power was the driver for restarting the construction. Welding residual stresses in nuclear power plant piping can lead to cracking concerns later in the life of the plant, especially for stress-corrosion cracking. Hence, understanding the residual stress distribution from welding is important to evaluate the reliability of pipe and nozzle joints with welds. In this paper, a large-diameter reactor pressure vessel (RPV) hot-leg nozzle was analyzed. This is a nozzle from Atucha II nuclear power plant in Argentina. The main piping material is 20MnMoNi55 with Tenacito 65R weld metal, and inner diameter (ID) welded cladding at the girth weld locations is made of 309L. The special materials and weld geometry will lead interesting welding residual stress fields. In addition, postweld heat treatment (PWHT) of the girth welds and its boundary conditions could also play an important role in determining welding residual stress fields at the plant’s normal operating conditions. Sensitivity analyses were conducted and the technical observations and comments are provided.
Effect of Plate Characteristics on Axial Dispersion and Heat Transfer in Plate Heat Exchangers
Authors: Shaji K. , Das Sarit K.
Published: March 2013

A new mathematical model of single-blow transient testing technique is proposed for the determination of heat transfer and dispersion coefficients in plate heat exchangers (PHEs) in which the flow maldisrtibution effects are separated from the fluid back-mixing. The fluid axial dispersion is used to characterize the back-mixing and other deviations from plug flow. Single-blow experiments are carried out with different number of plates for various flow rates with three different plate geometries of 30 deg, 60 deg, and mixed (30 deg/60 deg) chevron angles. The outlet temperature response to an exponential inlet temperature variation is solved numerically using finite difference method. In the present work, the whole curve matching technique is used to determine the values of Nusselt number and dispersive Peclet number. Since the maldistribution effects are separated, these data are independent of test conditions and hence using a regression analysis, general correlations are developed for Nusselt number and Peclet number of the present plate heat exchangers. The applicability of the single-blow test data is validated using a two-fluid experiment. Two-fluid experiments are conducted on the same plate heat exchanger with smaller and larger number of plates and the results have been compared with its simulation which used the Nusselt number and Peclet number correlations developed by the new model of single-blow test as the inputs.
Thermomechanics of Solids With Lower-Dimensional Energetics: On the Importance of Surface, Interface, and Curve Structures at the Nanoscale. A Unifying Review
Authors: Javili A. , McBride A. , Steinmann P.
Published: March 2013

Surfaces and interfaces can significantly influence the overall response of a solid body. Their behavior is well described by continuum theories that endow the surface and interface with their own energetic structures. Such theories are becoming increasingly important when modeling the response of structures at the nanoscale. The objectives of this review are as follows. The first is to summarize the key contributions in the literature. The second is to unify a select subset of these contributions using a systematic and thermodynamically consistent procedure to derive the governing equations. Contributions from the bulk and the lower-dimensional surface, interface, and curve are accounted for. The governing equations describe the fully nonlinear response (geometric and material). Expressions for the energy and entropy flux vectors, and the admissible constraints on the temperature field, all subject to the restriction of non-negative dissipation, are explored. A particular emphasis is placed on the structure of these relations at the interface. A weak formulation of the governing equations is then presented that serves as the basis for their approximation using the finite element method. Various forms for a Helmholtz energy that describes the fully coupled thermomechanical response of the system are given. They include the contribution from surface tension. The vast majority of the literature on surface elasticity is framed in the infinitesimal deformation setting. The finite deformation stress measures are, thus, linearized and the structure of the resulting stresses discussed. The final objective is to elucidate the theory using a series of numerical example problems.
Numerical Study of Fluid Flow and Heat Transfer in the Enhanced Microchannel With Oblique Fins
Authors: Lee Y. J. , Lee P. S. , Chou S. K.
Published: March 2013

Sectional oblique fins are employed in contrast to continuous fins in order to modulate flow in microchannel heat sink. The breakage of continuous fin into oblique sections leads to the reinitialization of both hydrodynamic and thermal boundary layers at the leading edge of each oblique fin, effectively reducing the thickness of boundary layer. This regeneration of entrance effect causes the flow to be always in a developing state thus resulting in better heat transfer. In addition, the presence of smaller oblique channels diverts a small fraction of flow into the adjacent main channels. The secondary flows thus created improve fluid mixing which serves to further enhance the heat transfer. Detailed numerical study on the fluid flow and heat transfer of this passive heat transfer enhancement technique provides insight to the local hydrodynamics and thermal development along the oblique fin. The uniquely skewed hydrodynamic and thermal profiles are identified as the key to the highly augmented and uniform heat transfer performance across the heat sink. The associated pressure drop penalty is much smaller than the achieved heat transfer enhancement, rendering it as an effective heat transfer enhancement scheme for single phase microchannel heat sink.
The Effectiveness of Secondary Flow Produced by Vortex Generators Mounted on Both Surfaces of the Fin to Enhance Heat Transfer in a Flat Tube Bank Fin Heat Exchanger
Authors: Song Ke-Wei , Wang Liang-Bi
Published: March 2013

Secondary flow is the flow in the cross section normal to the main flow. It plays an important role on the enhanced heat transfer and in the applications in other fields. Secondary flow can greatly enhance the convective heat transfer. In order to find the effectiveness of secondary flow for heat transfer enhancement, a nondimensional parameter, Se, based on the absolute vorticity flux is reported to specify the intensity of secondary flow. Its physical meaning is the ratio of inertial force to viscous force induced by secondary flow. As an example, the effectiveness of secondary flow was numerically studied for a flat tube bank fin heat exchanger with vortex generators (VGs) mounted on both surfaces of the fin. The contributions of VGs are investigated for the enhancements of secondary flow intensity, convective heat transfer, and pressure drop. The method is demonstrated using Se to find out the optimum configurations of VGs. The results reveal that close relationships exist not only between the span-average nondimensional intensity of secondary flow and the span-average Nusselt number but also between the volume average nondimensional intensity of secondary flow and the overall average Nusselt number. For the configuration studied, a ratio of Nusselt number enhancement to the friction factor enhancement increases with increasing the enhancement of secondary flow intensity. As a supplement to traditional criteria on a good performance heat transfer surface, the nondimensional intensity of secondary flow can be used clearly for an optimum value of VG parameter.
Geometric Design of Scroll Expanders Optimized for Small Organic Rankine Cycles
Authors: Orosz Matthew S. , Mueller Amy V. , Dechesne Bertrand J. , Hemond Harold F.
Published: March 2013

The application of organic Rankine cycles (ORCs) for small scale power generation is inhibited by a lack of suitable expansion devices. Thermodynamic and mechanistic considerations suggest that scroll machines are advantageous in kilowatt-scale ORC equipment, however, a method of independently selecting a geometric design optimized for high-volume-ratio ORC scroll expanders is needed. The generalized 8-dimensional planar curve framework (Gravesen and Henriksen, 2001, “The Geometry of the Scroll Compressor,” Soc. Ind. Appl. Math., 43, pp. 113–126), previously developed for scroll compressors, is applied to the expansion scroll and its useful domain limits are defined. The set of workable scroll geometries is: (1) established using a generate-and-test algorithm with inclusion based on theoretical viability and engineering criteria, and (2) the corresponding parameter space is related to thermodynamically relevant metrics through an analytic ranking quantity fc (“compactness factor”) equal to the volume ratio divided by the normalized scroll diameter. This method for selecting optimal scroll geometry is described and demonstrated using a 3 kWe ORC specification as an example. Workable scroll geometry identification is achieved at a rate greater than 3 s−1 with standard desktop computing, whereas the originally undefined 8-D parameter space yields an arbitrarily low success rate for determining valid scroll mating pairs. For the test case, a maximum isentropic expansion efficiency of 85% is found by examining a subset of candidates selected the for compactness factor (volume expansion ratio per diameter), which is shown to correlate with the modeled isentropic efficiency (R2 = 0.88). The rapid computationally efficient generation and selection of complex validated scroll geometries ranked by physically meaningful properties is demonstrated. This procedure represents an essential preliminary qualification for intensive modeling and prototyping efforts necessary to generate new high performance scroll expander designs for kilowatt scale ORC systems.