bluuebunny/crossref_metadata_2025 huggingface dataset:
A Role for the Inflammasome in Spontaneous Labor at Term
Authors: Romero Roberto , Xu Yi , Plazyo Olesya , Chaemsaithong Piya , Chaiworapongsa Tinnakorn , Unkel Ronald , Than Nandor Gabor , Chiang Po Jen , Dong Zhong , Xu Zhonghui , Tarca Adi L. , Abrahams Vikki M. , Hassan Sonia S. , Yeo Lami , Gomez‐Lopez Nardhy
Published: March 2016

Problem

Inflammasomes are signaling platforms that, upon sensing pathogens and sterile stressors, mediate the release of mature forms of interleukin (IL)‐1β and IL‐18. The aims of this study were to determine (i) the expression of major inflammasome components in the chorioamniotic membranes in spontaneous labor at term, (ii) whether there are changes in the inflammasome components associated with the activation of caspase‐1 and caspase‐4, and (iii) whether these events are associated with the release of the mature forms of IL‐1β and IL‐18.

Method of study

Chorioamniotic membranes were collected from women at term with and without spontaneous labor. mRNA abundance and protein concentrations of inflammasome components, nucleotide‐binding oligomerization domain‐containing (NOD)1 and NOD2 proteins, caspase‐1, caspase‐4, IL‐1β, and IL‐18 were quantified by qRT‐PCR (n = 28–29 each), ELISA (n = 10 each) or immunoblotting (n = 8 each), and immunohistochemistry (n = 10 each). Active caspase‐1 and caspase‐4, as well as mature IL‐18, were determined by immunoblotting (n = 4 each), and pro‐ and mature forms of IL‐1β were determined by ELISA (n = 4–7 each).

Results

Inflammasome components and NOD proteins were expressed in the chorioamniotic membranes obtained from women at term. The chorioamniotic membranes from women who underwent labor had (i) higher concentrations of NLRP3 (NOD‐like receptor family, pyrin domain‐containing protein 3) and NOD1 protein, (ii) greater immunoreactivity for caspase‐1 and caspase‐4, (iii) a greater quantity of the active form of caspase‐1 (p20), and (iv) higher mRNA abundance and protein concentrations of pro‐ and mature IL‐1β. However, mRNA abundance and protein concentrations of the mature form of IL‐18 were not increased in tissues from women who underwent labor at term.

Conclusions

Spontaneous labor at term is characterized by the expression of inflammasome components, which may participate in the activation of caspase‐1 and lead to the cleavage and release of mature IL‐1β by the chorioamniotic membranes. These results support the participation of the inflammasome in the mechanisms responsible for spontaneous parturition at term.
Sequential Model Selection-Based Segmentation to Detect DNA Copy Number Variation
Authors: Hu Jianhua , Zhang Liwen , Wang Huixia Judy
Published: March 2016

Array-based CGH experiments are designed to detect genomic aberrations or regions of DNA copy-number variation that are associated with an outcome, typically a state of disease. Most of the existing statistical methods target on detecting DNA copy number variations in a single sample or array. We focus on the detection of group effect variation, through simultaneous study of multiple samples from multiple groups. Rather than using direct segmentation or smoothing techniques, as commonly seen in existing detection methods, we develop a sequential model selection procedure that is guided by a modified Bayesian information criterion. This approach improves detection accuracy by accumulatively utilizing information across contiguous clones, and has computational advantage over the existing popular detection methods. Our empirical investigation suggests that the performance of the proposed method is superior to that of the existing detection methods, in particular, in detecting small segments or separating neighboring segments with differential degrees of copy-number variation.
Improving Efficiency Using the Rao–Blackwell Theorem in Corrected and Conditional Score Estimation Methods for Joint Models
Authors: Huang Yih-Huei , Hwang Wen-Han , Chen Fei-Yin
Published: March 2016

Longitudinal covariates in survival models are generally analyzed using random effects models. By framing the estimation of these survival models as a functional measurement error problem, semiparametric approaches such as the conditional score or the corrected score can be applied to find consistent estimators for survival model parameters without distributional assumptions on the random effects. However, in order to satisfy the standard assumptions of a survival model, the semiparametric methods in the literature only use covariate data before each event time. This suggests that these methods may make inefficient use of the longitudinal data. We propose an extension of these approaches that follows a generalization of Rao–Blackwell theorem. A Monte Carlo error augmentation procedure is developed to utilize the entirety of longitudinal information available. The efficiency improvement of the proposed semiparametric approach is confirmed theoretically and demonstrated in a simulation study. A real data set is analyzed as an illustration of a practical application.
Psychosocial correlates of oral hygiene behaviour in people aged 9 to 19 – a systematic review with meta‐analysis
Authors: Scheerman Janneke F. M. , van Loveren Cor , van Meijel Berno , Dusseldorp Elise , Wartewig Eva , Verrips Gijsbert H. W. , Ket Johannes C. F. , van Empelen Pepijn
Published: March 2016

Objectives

This systematic and meta‐analytic review aimed to quantify the association of psychosocial correlates with oral hygiene behaviour among 9‐ to 19‐year olds.

Methods

A systematic search up to August 2015 was carried out using the following databases: PubMed, PsycInfo, Embase, CINAHL and Web of Science. If necessary, authors of studies were contacted to obtain unpublished statistical information. A study was eligible for inclusion when it evaluated the association between the psychosocial correlates and oral hygiene behaviour varying from self‐reports to clinical measurements, including plaque and bleeding scores. A modified New Castle Ottawa Scale was applied to examine the quality of the included studies.

Results

Twenty‐seven data sets (k) presented in 22 publications, addressing nine psychosocial correlates, were found to be eligible for the meta‐analysis. For both tooth brushing and oral hygiene behaviour, random effect models revealed significant weighted average correlation (r+) for the psychosocial factors: ‘intention’, ‘self‐efficacy’, ‘attitude’ (not significant for tooth brushing), ‘social influence’, ‘coping planning’ and ‘action planning’ (r+ ranging from 0.18 to 0.57). Little or no associations were found for ‘locus of control’, ‘self‐esteem’ and ‘sense of coherence’ (r+ ranges from 0.01 to 0.08).

Conclusions

The data at present indicates that ‘self‐efficacy’, ‘intention’, ‘social influences’, ‘coping planning’ and ‘action planning’ are potential psychosocial determinants of oral health behaviour. Future studies should consider a range of psychological factors that have not been studied, but have shown to be important psychosocial determinants of health behaviours, such as ‘self‐determination’, ‘anticipated regret’, ‘action control’ and ‘self‐identity’. Effectiveness of addressing these potential determinants to induce behaviour change should be further examined by intervention trials.
Decreased physical activity, reduced QoL and presence of debilitating fatigue in patients with Addison's disease
Authors: van der Valk Eline S. , Smans Lisanne C.C.J. , Hofstetter Hedwig , Stubbe Janine H. , de Vries Marieke , Backx Frank J. G. , Hermus Ad R.M.M. , Zelissen Pierre M.J.
Published: March 2016

Background

Health‐related quality of life in patients with Addison's disease has been assessed in various European countries, indicating a reduced quality of life. However, no studies have addressed the impact of Addison's disease on physical activity.

Objective

The aim of this study was to investigate the quality of life in Dutch patients with Addison's disease particularly regarding the presence of fatigue and the ability to be physically active.

Methods

In this cross‐sectional study, a postal survey was performed among Dutch patients with Addison's disease on stable glucocorticoid replacement therapy with hydrocortisone or cortisone acetate. For quality of life and physical activity assessment, patients completed general and health‐related quality of life and physical activity questionnaires, and scores were compared to Dutch controls.

Results

A total of 328 patients with Addison's disease were studied. In patients with Addison's disease, only 45·7% met the standard of physical activity (Combinorm) compared to 67·8% of Dutch controls (P< 0·01). Forty‐eight per cent of patients showed abnormal fatigue, while 61% had severe fatigue. TheCISfatigue scores were significantly higher compared to controls (P< 0·01). We found reduced general subjective health‐related QoL scores in both male and female patients, especially in younger patients <65 years of age.

Conclusion

Physical activity is decreased in patients with Addison's disease, combined with a reduced subjective health‐related QoL and increased fatigue.
Outbreak of oriental yellow scale insect, Aonidiella orientalis (Newstead) (Homoptera: Diaspididae), on neem in Sudan
Authors: Ensaf S. I. M. , Inaam A. E. , Manal H. E.
Published: March 2016

Scale insects were observed in neem trees (Azadirachta indica A. Juss) planted in Shambatarea near the bank of the Nile in Khartoum State and along Blue Nile Street in Wad Medani, Gezira State, Sudan in October 2014. Specimens of neem leaves and twigs, which were highly infested with scale insects and showing signs of wilting, were collected from different parts of the tree canopies and sent to the Insect Collection Unit at the Agricultural Research Corporation, Gezira Research Station, Sudan for identification. The pest was morphologically identified as Aonidiella orientalis (Newstead) (Hemiptera: Diaspididae). An endoparasitoid was observed to emerge from the scale insect and was identified as an encyrtid wasp. Aonidiella orientalis had been recorded previously in Shambatarea in 1969 and this paper presents the results of surveys carried out following the initial observations in Khartoum and Gezira States. This was a major outbreak, affecting the majority of the 1685 surveyed neem trees and causing damage on 62.7% of them.
Incidence and spread of knockdown resistance (kdr) in German Colorado potato beetle (Leptinotarsa decemlineata Say) populations
Authors: Tebbe C. , Breckheimer B. , Racca P. , Schorn C. , Kleinhenz B. , Nauen R.
Published: March 2016

The Colorado beetle, Leptinotarsa decemlineata (Say), is one of the most important pests in many potato‐producing regions. Colorado beetle infestations are normally kept under economic damage thresholds by applying insecticides such as pyrethroids. Pyrethroids are known to act on voltage‐gated sodium channels and have been used for several decades to control L. decemlineata. Their continuous and widespread use has resulted in the development of resistance, which is often linked to a L1014F target‐site mutation in the voltage‐gated sodium channel, known as knockdown resistance (kdr). Since pyrethroids are used in many potato‐growing regions in Germany, more than 140 L. decemlineata samples were collected and analysed for the presence of the kdr allele by pyrosequencing diagnostics. Results showed that kdr is present in many German L. decemlineata populations, but even its homozygous presence does not substantially compromise the efficacy of recommended label rates of pyrethroids, as demonstrated by bioassays and crossing experiments. The implications of these findings for resistance management are briefly discussed.
Rolling contact fatigue cracking in rails subjected to in‐service loading
Authors: Haidemenopoulos G.N. , Sarafoglou P. I. , Christopoulos P. , Zervaki A.D.
Published: March 2016

Rolling contact fatigue (RCF) is one of the most important failure mechanisms in rails with significant cost‐ and safety‐related implications on the operation of railway systems. In this work, a metallurgical analysis of RCF crack initiation and propagation, including geometrical characteristics of RCF cracks – length, depth from surface, angle of propagation and spacing between cracks, is presented. The role of proeutectoid ferrite in crack initiation has been studied. Analysis of the fracture surface of an RCF crack revealed a ductile initiation zone followed by a quasi‐cleavage crack propagation. Iron oxide formed in the interior of all cracks in rails exposed to stagnant water with implications to crack propagation rate because of crack closure effects. Sequential sectioning parallel to the rolling surface revealed that RCF cracks possess convoluted surfaces. The crack trace expands with depth from the rolling surface. Subsurface crack initiation has also been documented.
Nutraceuticals in Migraine: A Summary of Existing Guidelines for Use
Authors: Rajapakse Thilinie , Pringsheim Tamara
Published: March 2016

Background

The use of nutraceuticals or food/herbal products for health benefits is expanding in adults with migraine as they seek relief from pain in an effective and tolerable manner not always afforded by current conventional pharmacologic therapies. Guidelines from the American Academy of Neurology/American Headache Society, Canadian Headache Society, and European Federation of Neurological Societies have discussed nutraceuticals in varying degrees of detail with at times conflicting recommendations.

Conclusion

This review serves to provide a summary of existing guidelines for the use of certain nutraceuticals including riboflavin, coenzyme Q10, magnesium, butterbur, feverfew, and omega‐3 polyunsaturated fatty acids. The review will also discuss the regulation of nutraceuticals in North America and the current controversy regarding butterbur and its safety.
New class divisions in a modern working life?
Authors: Skoland Kathrine , Solberg Astrid , Holte Kari Anne
Published: March 2016

This article questions the usefulness of a traditional class divide as a tool for understanding a contemporary working environment among manual and non‐manual workers in the oil service industry. The case of study is an enterprise within a supply chain with asymmetrical relationships between companies. Our findings show that the traditional manual/non‐manual class division is still relevant for understanding differences in perceived work situation in a modern work organisation. However, alongside a cleavage between manual and non‐manual workers, we find a cleavage between workers with differing amounts of contact with employees in organisations higher up in the supply chain.
Effects of the 2010 Haiti Earthquake on Women's Reproductive Health
Authors: Behrman Julia Andrea , Weitzman Abigail
Published: March 2016

This article explores the effects of the 2010 Haiti earthquake on women's reproductive health, using geocoded data from the 2005 and 2012 Haiti Demographic and Health Surveys. We use geographic variation in the destructiveness of the earthquake to conduct a difference‐in‐difference analysis. Results indicate that heightened earthquake intensity reduced use of injectables—the most widely used modern contraceptive method in Haiti—and increased current pregnancy and current unwanted pregnancy. Analysis of impact pathways suggests that severe earthquake intensity significantly increased women's unmet need for family planning and reduced their access to condoms. The earthquake also affected other factors that influence reproductive health, including women's ability to negotiate condom use in their partnerships. Our findings highlight how disruptions to health care services following a natural disaster can have negative consequences for women's reproductive health.
Caries Detection around Restorations Using ICDAS and Optical Devices
Authors: Diniz Michele Baffi , Eckert George Joseph , González‐Cabezas Carlos , Cordeiro Rita de Cássia Loiola , Ferreira‐Zandona Andrea Gonçalves
Published: March 2016

Purpose

Secondary caries is the major reason for replacement of restorations in operative dentistry. New detection methods and technology have the potential to improve the accuracy for diagnosis of secondary carious lesions. This in vitro study evaluated the performance of the ICDAS (International Caries Detection and Assessment System) visual criteria and optical devices for detecting secondary caries around amalgam and composite resin restorations in permanent teeth.

Materials and Methods

A total of 180 extracted teeth with Class I amalgam (N = 90) and resin composite (N = 90) restorations were selected. Two examiners analyzed the teeth twice using the visual criteria (ICDAS), laser fluorescence (LF), light‐emitting diode device (MID), quantitative light‐induced fluorescence system (QLF), and a prototype system based on the Fluorescence Enamel Imaging technique (Professional Caries Detection System, PCDS). The gold standard was determined by means of confocal laser scanning microscopy.

Results

High‐reproducibility values were shown for all methods, except for MID in the amalgam group. For both groups the QLF and PCDS were the most sensitive methods, whereas the other methods presented better specificity (p < 0.05).

Conclusion

All methods, except the MID device appeared to be potential methods for detecting secondary caries only around resin composite restorations, whereas around amalgam restorations all methods seemed to be questionable.

Clinical Significance

Using Internal Caries Detection and Assessment System (ICDAS), an LF device, quantitative light‐induced fluorescence and a novel method based on Fluorescence Enamel Imaging technique may be effective for evaluating secondary caries around composite resin restorations.
Sound production by the Shi drum Umbrina cirrosa and comparison with the brown meagre Sciaena umbra: a passive acoustic monitoring perspective
Authors: Picciulin M. , Bolgan M. , Corò A. B. , Calcagno G. , Malavasi S.
Published: March 2016

Sounds produced by the Shi drum Umbrina cirrosa were short trains of pulses with an average pulse period of 180 ms, pulse duration of c. 40 ms and an average peak frequency of 400 Hz; average values of acoustical properties differed from those recorded from the brown meagre Sciaena umbra in previous studies. The present study provides a preliminary tool for discriminating between these two species while conducting passive acoustic monitoring. The potential effects of ontogeny on sound production in both species are discussed and recommendations are made for further research.
Malnutrition increases NO production and induces changes in inflammatory and oxidative status in the distal colon of lactating rats
Authors: dos Santos‐Júnior E. F. , Gonçalves‐Pimentel C. , de Araújo L. C. C. , da Silva T. G. , de Melo‐Júnior M. R. , Moura‐Neto V. , Andrade‐da‐Costa B. L. D. S.
Published: March 2016

Background

Epidemiological studies have indicated the lack of breast feeding as a risk factor associated with later development of inflammatory bowel disease. Nevertheless, the repercussion of little feeding during suckling on large intestine inflammatory response and anti‐oxidant resources has not yet been completely understood. This study hypothesized that unfavorable lactation is able to induce oxidative stress and release of inflammatory mediators modifying the integrity of the colon epithelium in weanling rats.

Methods

Wistar rats were reared under different early nutritional conditions according to litter size in two groups: N6 (6 pups/dam) and N15 (15 pups/dam) until the 25th postnatal day. The distal colon was removed and processed for biochemical, morphometric, and immunohistochemical analyzes. Lipoperoxidation, nitric oxide (NO), reduced (GSH) and oxidized (GSSG) glutathione, tumor necrosis factor‐alpha (TNF‐α), interleukins‐1β, 4 and 10 (IL‐1β; IL‐4; IL‐10) levels, and total superoxide dismutase (tSOD), and catalase (CAT) activities were assessed. Morphometric analysis was carried out using paraffin sections and wholemount myenteric plexus preparations.

Key Results

Increased lipoperoxidation, NO, TNF‐α and IL‐1b levels, reduced tSOD and increased CAT activities were found in the N15 compared to N6 group. No intergroup difference was detected for IL‐10, while lower levels of IL‐4, GSH and GSSG and lower neuronal size and density were induced by undernutrition.

Conclusions & Inferences

Reduced feeding during suckling changed the inflammatory response and oxidative status in the colon of weanling rats. These data suggest potential mechanisms by which malnutrition early in life may increase the vulnerability of the large intestine to insults.
Language Use and Violence: Assessing the Relationship Between Linguistic Context and Macrolevel Violence
Authors: Feldmeyer Ben , Harris Casey T. , Lai Daniel
Published: March 2016

Scholars have produced a sizable body of research assessing the macrolevel links between immigration and crime. However, researchers have given far less attention to related questions about the effects of language use on aggregate levels of violence. The current study addresses this gap in research by exploring the ways that patterns of language use—specifically, language heterogeneity and Spanish‐language concentration—are related to year 2010 serious violent crime rates for nearly 2,900 census places across the United States. Results of our analysis reveal that linguistic heterogeneity is associated with increased violence and that this relationship is stronger in disadvantaged contexts. In contrast, Spanish‐language concentration appears to be protective against violence and mitigates the violence‐generating effects of structural disadvantage, net of immigration and other macrostructural characteristics. Implications of these findings for research on immigration, communities and crime, and related theoretical perspectives on immigrant revitalization and macrostructural theories of crime are discussed.
Mobilization of autologous and allogeneic peripheral blood stem cells for transplantation in haematological malignancies using biosimilar G‐CSF
Authors: Schmitt M. , Hoffmann J.‐M. , Lorenz K. , Publicover A. , Schmitt A. , Nagler A.
Published: March 2016

Background and Objectives

Biosimilars of the granulocyte colony stimulating factor (G‐CSF) filgrastim were approved by the European Medicines Agency (EMA) for registered indications of the originator G‐CSF, including prevention and treatment of neutropenia, as well as mobilization of peripheral blood stem cells in 2008. Nevertheless, there is still an ongoing debate regarding the quality, efficacy and safety of biosimilar G‐CSF.

Materials and Methods

This article is a meta‐analysis of clinical studies on the use of biosimilar G‐CSF for mobilization and transplantation of haematopoietic stem cells as available in public databases. All data sets were weighted for the number of patients and parameters and then subjected to statistical meta‐analysis employing the Mann–Whitney U‐test followed by the Hodges–Lehmann estimator to assess differences between biosimilar and originator G‐SCF.

Results

A total of 1892 individuals, mostly with haematological malignancies but also including 351 healthy donors have been successfully mobilized for autologous or allogeneic stem cell transplantation using biosimilar G‐CSF (ZarzioTM: 1239 individuals; RatiograstimTM/TevagrastimTM: 653 individuals). A total of 740 patients with multiple myeloma, 491 with non‐Hodgkin's lymphoma (NHL), 150 with Hodgkin's lymphoma (HL) and other diseases are included in this meta‐analysis, as well as 161 siblings and 190 volunteer unrelated donors. For biosimilar and originator G‐CSF, bioequivalence was observed for the yield of CD34+ stem cells as well as for the engraftment of the transplants.

Conclusion

Biosimilar G‐CSF has equivalent effects and safety as originator G‐CSF.
Simple Thermal Model to Select Electromagnetic Launcher Tribomaterials
Authors: Balic Edin E. , Blanchet Thierry A.
Published: March 2016

Lab-scale electromagnetic launcher (EML) tests for the baseline case of an aluminum armature spanning a pair of copper rails reproduced excessive aluminum melt wear depth leading to loss of conductive contact and resultant electrical transition before completion of launch. A simple thermal model partitioning interfacial Joule heat input between conduction into the rails and melting of the armature provided compact expressions describing armature wear behavior. A quantity from this expression, termed the armature melt resistance (AMR), predicts a decrease of armature wear and the likelihood for resultant electrical transition with increasing rail thermal conductivity and heat capacity, as well as armature heat capacity, latent heat, and melt point. With this AMR metric to guide materials' selection, in subsequent tests, a slight increase in wear indeed occurred upon substitution of stainless steel rails, with more dramatic order of magnitude decreases in wear and avoidance of electrical transition instead realized upon substitution of solid molybdenum armatures.
Analysis of Passive Filling With Fibrotic Myocardial Infarction
Authors: Masithulela Fulufhelo
Published: March 2016

Cardiovascular diseases account for one third of all deaths worldwide, more than 33% of which are related to ischemic heart disease, involving a myocardial infarction (MI). Following myocardial infarction, the injured region and ventricle undergo structural changes which are thought to be caused by elevated stresses and reduction of strains in the infarcted wall. The fibrotic phase is defined as the period when the amount of new collagen and number of fibroblasts rapidly increase in the infarcted tissue. We studied through finite element analysis the mechanics of the infarcted and remodeling rat heart during diastolic filling. Biventricular geometries of healthy and infarcted rat hearts reconstructed from magnetic resonance images were imported in Abaqus©. The passive myocardium was modelled as a nearly incompressible, hyperelastic, transversely isotropic material represented by the strain energy function W = ½C(eQ − 1) with Q = bfE112 + bt(E222 + E332 + E322) + bfs(E122 + E212 + E132 + E312). Material parameters were obtained from literature [1]. As boundary conditions, the circumferential and longitudinal displacements at the base were set to zero. The radial displacements at the base were left free. A linearly increasing pressure from 0 to 3.80 kPa and 0.86 kPa, respectively, was applied to the endocardial surfaces of left and right ventricle. Average radial, circumferential and longitudinal strains during passive filling were −0.331, 0.135, 0.042 and −0.250, −0.078 and 0.046 for the healthy heart and the infarcted heart, respectively. The average radial, circumferential and longitudinal stresses were −1.196 kPa, 3.87 kPa in the healthy heart and 0.424 kPa and −1.90 kPa, 8.74 kPa and 1.69 kPa in the infarcted heart. The strains were considerable lower in the infarcted heart compared to the health heart whereas stresses were higher in the presence of an infarct compared to the healthy case. The results of this study indicate the feasibility of the models developed for a more comprehensive assessment of mechanics of the infarcted ventricle including extension to account for cardiac contraction.
The Effect of Over-Loaded Right Ventricle During Passive Filling in Rat Heart: A Biventricular Finite Element Model
Authors: Masithulela Fulufhelo
Published: March 2016

The physiological basis of the right ventricle diastolic function is not well studied. In most heart failure, heart transplantation remains the first choice with survival ranges between 40% and 50%. It is known that heart transplantation lacks donors and therefore, there is a need to search for new surgical techniques for heart failure prevention. This study utilized the finite elment method to study the structural behavior of heart wall under severe pressures. In this study the effect RV filling during over-pressurised RV using bi-ventricular model has been studied using finite element modeling (FEM). Cardiovascular disease (CVD) is the leading cause of death in low-income and middle-income countries. The right ventricle (RV) dysfunction is understood to have an impact on the performance of the left ventricle (LV) but the mechanisms remain poorly understood. Finite strain analyses of bi-ventricular model provide important information on the heart function. The passive myocardium was modelled as a nearly incompressible, hyperelastic, transversely isotropic material. Biventricular geometries of healthy and infarcted rat hearts reconstructed from magnetic resonance images were imported in Abaqus©. In simulating the passive filling of the healthy condition of the rat heart, the inner walls of the LV and RV the pressures of 4.8 kPa and 0.0098 kPa were applied respectively. The average circumferential strain was found to be 0.138 and 0.100 on the endocardium of the over-pressured and healthy model respectively. The high stresses and strains on the over-loaded model were observed.
Application of Speed Transform to Diagnosis of Rotating Machinery With Varying Speeds
Authors: Zang Tingpeng , Wen Guangrui , Xu Guanghua
Published: March 2016

The rotor startup vibration signals carry abundant dynamic information of the machinery and are very useful for feature extraction and potential early fault diagnosis. Due to the non-stationary and transient nature of the signals in speed up process, the traditional diagnostic methods that have been put forward based on stationary assumption are no longer satisfactory. This paper proposes a new Speed Transform based method for the fault diagnosis of rotating machinery in variable speed. Speed Transform decomposes a complicated signal over a basis of elementary oscillatory functions, whose frequencies follow the speed variation. The effectiveness of the proposed method is demonstrated by both simulated signal and startup vibration signal collected from a rotor system with early rub-impact fault. Analyzed results showed that the proposed method could effectively extract fault features of the rotor under varying speed condition.
Reduction of Turbine Blade Tip Leakage Losses and Excitation Forces by Passive Tip Injection
Authors: aus der Wiesche Stefan , Passmann Maximilian , Willinger Reinhard
Published: March 2016

The reduction of turbine blade-tip losses by means of passive tip injection was theoretically investigated. The analysis employed an analytical expression of the blade-tip discharge coefficient. The resulting blade-tip excitation forces (i. e. Thomas-Alford forces) were explicitly evaluated for unshrouded turbines with and without passive tip injection. It was found, that the Thomas-Alford coefficient for cross-force can substantially increase when the blade-tip gap was reduced. This observation can directly be explained on the basis of viscous flow effects through the gap, and it was in excellent agreement with available literature data. Due to passive tip injection, a slight decrease of the blade-tip excitation cross-force was obtained. The potential of the reduction of the cross-force due to passive tip injection was found to be comparable to the corresponding tip loss reduction.
Better Learning Success in Engineering Mechanics
Authors: Wangenheim Matthias , Engelmann Sarah , Haupt Frank
Published: March 2016

Studying engineering mechanics is mandatory for every engineering student at Leibniz Universität Hannover (LUH). The course is divided into four parts (statics, elastostatics, kinetics and kinematics, dynamics) and is taught over a period of two years at the very beginning of each study program. While students’ evaluations of our courses are good in general, we face a high failure rate in the exams, which are written once at the end of each course. In later stages of the engineering study programs, it seems hard to for us enthusing students for our research topics. Thus, finding M.Sc. or PhD students is more difficult for us than it should be. In a university funded, internal 12-month project we aim to optimize our Engineering Mechanics Tutorials, which provide a specific, relatively interactive form of teaching to the students. With internal and external consultancy by professional lecturers and didactics trainers, our project team has developed a course of actions and measures to raise the academic success of our students. In this publication we will discuss these actions as well as ways to measure and verify their success.
Investigation of the Blade Tip Clearance Effects on Performance and Stability of a Mixed-Flow Pump: High Speed Camera Recordings of the Flow Structures, Local Measurements and Numerical Simulation
Authors: Serena Alberto , Bakken Lars E.
Published: March 2016

The tip leakage flow affects turbomachines performance generating losses and reducing the effective blading; in addition, unsteady phenomena arise, negatively influencing the machine stability.

In this paper, an overview of the existing models is presented. Local measurements of the pressure pulsations, visual flow observations and high quality video recordings from a high speed camera are performed in a novel pump laboratory, which provides the desired visualization of the rotating channels, and allows to study the fluctuating and intermittent nature of this phenomenon, and detect any asymmetry among the channels.

A detailed comparison of the vortex tip structure for various tip clearances and with a whole set of numerical simulations finally completes the analysis.

The three main focus areas are: tip vortex location, structure and evolution, performance comparison between shrouded and open impeller, at different tip clearance sizes, and study of the rotating instabilities.
Study of Cutting Forces and Surface Roughness in Milling of Carbon Fibre Composite (CFC) With Conventional and and Pressurized CO2 Cutting Fluids
Authors: Dahnel Aishah Najiah , Kibbler Christopher , Barnes Stuart , Ascroft Helen
Published: March 2016

Carbon Fibre Composites (CFC) are commonly used in aerospace, automotive and civil industries to manufacture high performance products which require high strength with low weight. They are usually produced to near net shape, however machining such as milling is frequently performed to achieve dimensional accuracy. This paper presents the effect of using conventional (water-based) and carbon dioxide (CO2) cutting fluids during milling of CFC on cutting forces, temperature and surface roughness in comparison to dry milling. Milling experiments were conducted using uncoated tungsten carbide milling routers at a constant feed rate and depth of cut of 0.025 mm/rev and 5 mm, respectively. Cutting speeds used were 100, 150 and 200 m/min. Cutting forces were measured using a dynamometer, temperatures during milling were measured at the workpiece by thermocouples and surface roughness (Ra) of the milled surfaces were measured using a surface profilometer. Milling with conventional and CO2 cutting fluids resulted in higher cutting forces than dry milling at all cutting speeds used. This was attributed to cooling of the CFC, which retained the strength of polymer matrix during machining. Cutting temperatures were the highest and reached beyond 100°C during dry milling. The use of conventional cutting fluid during milling provided significant cooling to the workpiece, in which cutting temperatures were maintained below 30°C at all cutting speeds used. Cooling the workpiece during milling with CO2 cutting fluid resulted in cutting temperatures within the range of 65–86°C. Even though the application of cutting fluids during milling generated higher cutting forces than dry milling, it produced favourable results in terms of surface finish. The use of cutting fluid during machining CFC is shown to be highly effective in sustaining the strength of CFC materials as a result of low cutting temperature.
Estimation of Machine Vision and Acoustic Emission Parameters for Tool Status Monitoring in Turning Using Artificial Neural Network
Authors: Chethan Y. D. , Venkatadas Ravindra Holalu , Krishne Gowda Y. T.
Published: March 2016

Tool status monitoring is a fundamental aspect in the evolution of production techniques. As the quality of the cutting tool is directly related to the quality of the product, the level of tool status should be kept under control during machining operations. An attempt is made here to extract maximum information from image captured from machine vision and Acoustic Emission (AE) signals acquired during turning of Inconel 718 nickel alloy. Nickel-base super alloy Inconel 718 is a high-strength, thermal-resistant. Because of its excellent mechanical properties, it plays an important part in recent years in aerospace, petroleum and nuclear energy industries. Due to the extreme toughness and work hardening characteristic of the alloy, the problem of machining Inconel 718 is one of ever-increasing magnitude. The experiments were conducted for different cutting speed and feed combinations. An image processing method, the blob analysis technique, was used to extract parameters called features representing the state of the cutting tool. Area and perimeter of the machine vision, AE RMS and AE COUNT of the AE signals studied as features and found to be effective in tool condition monitoring. Once all these features are extracted after preliminary processing of image and AE signals, tool Status, whether worn out or not worn out (serviceable), is decided on the basis of extracted features. In this study, theoretical estimation using ANN is carried out for machine vision parameters like Wear area and perimeter Acoustic Emission parameters like AE RMS and AE COUNT. In estimating vision parameter i.e. Wear area: perimeter, machining time, AE RMS, AE COUNT are considered as the independent variables and vice versa in order to have the performance well in multi sensory situations. In order to identify the tool status based on the signal measured, an Artificial Neural Network, using a Feed Forward Back-Propagation algorithm, has been adopted. The input parameters that are being used for estimation in this study were found to be non linearly varying with the desired output. The training and estimation has generated closer outputs as compared to the wear area observed from the machine vision approach and AE RMS from the acoustic emission approach. Artificial neural network estimates have better correlation at higher feed rate. Under these conditions, there will be large scale values, resulting in vision and AE parameters. Due to higher values, correlation may have been better.
A Computational Study on Non-Uniform Cross-Sectional Deformability-Based CTC Separation Devices
Authors: Aghaamoo Mohammad , Xu Jie , Chen Xiaolin
Published: March 2016

Cancer is one of the most dangerous diseases widespread around the world. Developing the most efficient cures for cancer strongly relies on a comprehensive understanding of cancer cells. Circulating Tumor Cells (CTCs) are cancer cells detached from the primary tumor site and released into the blood. CTCs are the main source of cancer metastasis. Devising devices to identify and separate these cells from the blood is of great importance since these cells represent cancer in many aspects. Because of the rarity of CTCs in the blood, designing efficient CTC separation devices has become a challenging issue. Among different CTC separation devices, deformability-based CTC separation devices have become very popular recently because of their simplicity and their relatively low cost. In this research, we investigate numerically the deformability-based CTC separation microfilters. Specifically, we study non-uniform cross-sectional microfilters because of their ability in unclogging. Different microfilter geometries are selected for this study including conical-shaped and rectangular cross-section microfilters with different channel profiles. In this study, we mainly focus on the effect of different design parameters on system performance criteria. The main performance criteria are: critical pressure of the system, system throughput and cell clogging in filtration. Critical pressure, which is defined as the maximum pressure for a cancer cell to squeeze through the microfilter, is an important design aspect. Applying a pressure lower than the critical pressure causes the cell to get stuck in the microfilter, while applying much higher pressure on the system may result in cellular damage which has negative effect on the viability of the cell for post processing. System throughput is also of great importance. A high-throughput CTC filtration system is always more desirable in clinic applications. System clogging, which decreases the CTC separation efficiency, is one of the challenging issues in these devices. In this research, we first simulate how a cell behaves in a passing event process through the microfilter. Specifically, we focus on how different cells squeeze through the microfilter. This gives us more insight through the separation process. Second, we investigate the effect of different microfilter geometries on the critical pressure required for separation of cancer cells. Third, the effect of applied inlet pressure on the system performance is studied. Our results indicate that the critical pressure varies significantly with microfilter geometry. Results also show that the device throughput is strongly related to the applied pressure. Moreover, the filtration simulation demonstrates that system clogging occurs if unsuitable pressure is applied on the system.
On the Overall Properties of Composites Reinforced by Fibers With Prescribed Orientations
Authors: Morenko Yana , Krokhmal Pavlo , Zhupanska Olesya I.
Published: March 2016

This study is concerned with development of bounds on the elastic properties of fiber reinforced composites with arbitrary orientational distribution of fibers. Generalization of the Mori-Tanaka model [1] and Hashin-Schtrikman variational bounds [2] to the cases of non-aligned composite phases are examined. Orientation distribution functions (ODF) are used to describe orientation probability density. It is shown that the Mori-Tanaka scheme applied to the non-aligned fiber reinforced composites violates symmetry of the effective elastic moduli tensor. The study of the literature also reveals that there are no known bounds derived for the composites with orientational distribution (except for the random uniform distribution) of phases. To overcome this issue we propose to formulate a problem of finding tightest bounds for the composites with non-aligned phases as a nonlinear semidefinite optimization problem, i.e., an optimization problem where the optimization variables are represented by symmetric positive semidefinite matrices. Such a formulation guarantees that any solution of the optimization problem represents a valid tensor of elastic material properties. The optimization problem then is solved by an interior point method to produce optimal bounds for the overall elastic properties of two-phase composite with uniform distribution of carbon nanotubes in a polymer matrix.
Proportional Integral Control Approach for Controlling the Temperatures of Multi-Steel Cylinders Barrel in an Injection Molding Machine
Authors: Abu-Ayyad Ma’moun , Khilnani Tapan
Published: March 2016

This work presents a three dimensional prototype of the surface model to demonstrate the working of the controller. The three dimensional surface model is a prototype of the Injection Molding Machine (IMM), wherein the temperature of the system needs to be gradually increased to a very high temperature to melt plastics uniformly, despite the non-linear process. This process tends to be non-linear mainly due to thermal loss, heat transfer between the three cylinders and atmospheric disturbances. This paper presents a unique approach for designing a nonlinear surface model-based for controlling the temperature of multi steel cylinders in an injection molding machine. The innovation of this strategy is that the controller structure uses the nonlinear model to update the process variables at every sampling instant while the closed-loop control is executed. In this work, a new optimization routine will be used to minimize the errors between the model and process outputs. This allows the determination of the system’s variables resulting in a new set of the Proportional Integral (PI) controller parameters with every sampling instant. The most important feature of 3-dimensional surface model control strategy is that it uses the process’ variables to construct the surface model which are used in calculation of the control actions. In the meantime, this surface model is constructed offline by conducting several open-loop tests using different input signals and profiles while the measured output of the process is recorded. From these data, the main dynamic parameters of the process (process gain and time constant) are extracted to construct the surface model. Finally, the control law of the PI approach is updated every sampling instant to counteract the nonlinear effects of the system. In order to achieve a good control response for this process, an accurate model has to be developed to design a robust controller that can follow the reference trajectory and track the setpoint changes smoothly. Also, the model has to be of the adaptive form so that the controller has the ability to reject any disturbances or noisy feedback.
Numerical Simulation of the Healing Process in the Tibia Diaphysis Fracture Fixed With External Fixation
Authors: Wang Haosen , Hao Zhixiu , Wen Shizhu , Wan Chao
Published: March 2016

The tibia diaphysis (shaft) fracture is one of the most common long bone fractures, and is usually treated with either the internal or the external fixations. How to choose a proper fixation type is still empirical and controversial. The objective of this study was to investigate whether the lateral external fixation (LEF) is suitable to treat the transverse and oblique tibia diaphysis fracture, from a mechanobiological perspective. The healing processes in the tibia fractures were simulated using the finite element method. The models of both the transverse and oblique (45°) tibia diaphysis fracture fixed with a LEF were built. A mechano-bioregulatory algorithm, which considered both the mechanobiological and biological environments, was developed to simulate the cell and tissue activities inside the callus. The results showed that both fractures healed in a typical secondary osteogenesis process. After 60 days, the regions of external callus and bone marrow were occupied with bone tissue. However, the mechanical stimulus in the inter-cortical region in the oblique fracture model with a less stiff LEF was greater than the stimulus in the transverse fracture model with the same LEF, indicating that the angled fracture was prone to generate greater instability. Moreover, increased osteogenic differentiation threshold only slightly affected the bone formation in the bridging areas, thus, had minor influences on the healing process. In conclusion, the lateral external fixation demonstrated satisfactory capacity in the treatment of the transverse and oblique tibia diaphysis fracture. The oblique fracture was more likely to be affected with a less stiff fixation.
Energy Harvesting From Smart Materials
Authors: Hosking Nathan S. , Sotoudeh Zahra
Published: March 2016

In this paper, we study fully coupled electromagnetic-elastic behaviors present in the structures of smart beams using variational asymptotic beam sections and geometrically exact fully intrinsic beam equations. We present results for energy harvesting from smart beams under various oscillatory loads in both the axial and transverse directions and calculate the corresponding deformations. The magnitude of these loads are varied to show the generalized trends produced by piezoelectric materials. Smart materials change mechanical energy to electrical energy; therefore, changing the structural dynamic behavior of the structure and its stiffness matrix. A smart structure can be designed to undergo larger loads without changing the surface area of the cross-section.