bluuebunny/crossref_metadata_2025 huggingface dataset:
Deletion of proapoptotic Puma selectively protects hematopoietic stem and progenitor cells against high-dose radiation
Authors: Shao Lijian , Sun Yan , Zhang Zhonghui , Feng Wei , Gao Yongxing , Cai Zailong , Wang Zack Z. , Look A. Thomas , Wu Wen-Shu
Published: April 2010

Bone marrow injury is a major adverse side effect of radiation and chemotherapy. Attempts to limit such damage are warranted, but their success requires a better understanding of how radiation and anticancer drugs harm the bone marrow. Here, we report one pivotal role of the BH3-only protein Puma in the radiosensitivity of hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs). Puma deficiency in mice confers resistance to high-dose radiation in a hematopoietic cell–autonomous manner. Unexpectedly, loss of one Puma allele is sufficient to confer mice radioresistance. Interestingly, null mutation in Puma protects both primitive and differentiated hematopoietic cells from damage caused by low-dose radiation but selectively protects HSCs and HPCs against high-dose radiation, thereby accelerating hematopoietic regeneration. Consistent with these findings, Puma is required for radiation-induced apoptosis in HSCs and HPCs, and Puma is selectively induced by irradiation in primitive hematopoietic cells, and this induction is impaired in Puma-heterozygous cells. Together, our data indicate that selective targeting of p53 downstream apoptotic targets may represent a novel strategy to protecting HSCs and HPCs in patients undergoing intensive cancer radiotherapy and chemotherapy.
Platelets regulate lymphatic vascular development through CLEC-2–SLP-76 signaling
Authors: Bertozzi Cara C. , Schmaier Alec A. , Mericko Patricia , Hess Paul R. , Zou Zhiying , Chen Mei , Chen Chiu-Yu , Xu Bin , Lu Min-min , Zhou Diane , Sebzda Eric , Santore Matthew T. , Merianos Demetri J. , Stadtfeld Matthias , Flake Alan W. , Graf Thomas , Skoda Radek , Maltzman Jonathan S. , Koretzky Gary A. , Kahn Mark L.
Published: April 2010

Although platelets appear by embryonic day 10.5 in the developing mouse, an embryonic role for these cells has not been identified. The SYK–SLP-76 signaling pathway is required in blood cells to regulate embryonic blood-lymphatic vascular separation, but the cell type and molecular mechanism underlying this regulatory pathway are not known. In the present study we demonstrate that platelets regulate lymphatic vascular development by directly interacting with lymphatic endothelial cells through C-type lectin-like receptor 2 (CLEC-2) receptors. PODOPLANIN (PDPN), a transmembrane protein expressed on the surface of lymphatic endothelial cells, is required in nonhematopoietic cells for blood-lymphatic separation. Genetic loss of the PDPN receptor CLEC-2 ablates PDPN binding by platelets and confers embryonic lymphatic vascular defects like those seen in animals lacking PDPN or SLP-76. Platelet factor 4-Cre–mediated deletion of Slp-76 is sufficient to confer lymphatic vascular defects, identifying platelets as the cell type in which SLP-76 signaling is required to regulate lymphatic vascular development. Consistent with these genetic findings, we observe SLP-76–dependent platelet aggregate formation on the surface of lymphatic endothelial cells in vivo and ex vivo. These studies identify a nonhemostatic pathway in which platelet CLEC-2 receptors bind lymphatic endothelial PDPN and activate SLP-76 signaling to regulate embryonic vascular development.
Globin-like proteins in Caenorhabditis elegans: in vivo localization, ligand binding and structural properties
Authors: Geuens Eva , Hoogewijs David , Nardini Marco , Vinck Evi , Pesce Alessandra , Kiger Laurent , Fago Angela , Tilleman Lesley , De Henau Sasha , Marden Michael C , Weber Roy E , Van Doorslaer Sabine , Vanfleteren Jacques , Moens Luc , Bolognesi Martino , Dewilde Sylvia
Published: April 2010

Background

The genome of the nematode Caenorhabditis elegans contains more than 30 putative globin genes that all are transcribed. Although their translated amino acid sequences fit the globin fold, a variety of amino-acid substitutions and extensions generate a wide structural diversity among the putative globins. No information is available on the physicochemical properties and the in vivo expression.

Results

We expressed the globins in a bacterial system, characterized the purified proteins by optical and resonance Raman spectroscopy, measured the kinetics and equilibria of O2 binding and determined the crystal structure of GLB-1* (CysGH2 → Ser mutant). Furthermore, we studied the expression patterns of glb-1 (ZK637.13) and glb-26 (T22C1.2) in the worms using green fluorescent protein technology and measured alterations of their transcript abundances under hypoxic conditions.GLB-1* displays the classical three-over-three α-helical sandwich of vertebrate globins, assembled in a homodimer associated through facing E- and F-helices. Within the heme pocket the dioxygen molecule is stabilized by a hydrogen bonded network including TyrB10 and GlnE7.GLB-1 exhibits high ligand affinity, which is, however, lower than in other globins with the same distal TyrB10-GlnE7 amino-acid pair. In the absence of external ligands, the heme ferrous iron of GLB-26 is strongly hexacoordinated with HisE7, which could explain its extremely low affinity for CO. This globin oxidizes instantly to the ferric form in the presence of oxygen and is therefore incapable of reversible oxygen binding.

Conclusion

The presented data indicate that GLB-1 and GLB-26 belong to two functionally-different globin classes.
Predicting protein-protein interactions in unbalanced data using the primary structure of proteins
Authors: Yu Chi-Yuan , Chou Lih-Ching , Chang Darby Tien-Hao
Published: April 2010

Background

Elucidating protein-protein interactions (PPIs) is essential to constructing protein interaction networks and facilitating our understanding of the general principles of biological systems. Previous studies have revealed that interacting protein pairs can be predicted by their primary structure. Most of these approaches have achieved satisfactory performance on datasets comprising equal number of interacting and non-interacting protein pairs. However, this ratio is highly unbalanced in nature, and these techniques have not been comprehensively evaluated with respect to the effect of the large number of non-interacting pairs in realistic datasets. Moreover, since highly unbalanced distributions usually lead to large datasets, more efficient predictors are desired when handling such challenging tasks.

Results

This study presents a method for PPI prediction based only on sequence information, which contributes in three aspects. First, we propose a probability-based mechanism for transforming protein sequences into feature vectors. Second, the proposed predictor is designed with an efficient classification algorithm, where the efficiency is essential for handling highly unbalanced datasets. Third, the proposed PPI predictor is assessed with several unbalanced datasets with different positive-to-negative ratios (from 1:1 to 1:15). This analysis provides solid evidence that the degree of dataset imbalance is important to PPI predictors.

Conclusions

Dealing with data imbalance is a key issue in PPI prediction since there are far fewer interacting protein pairs than non-interacting ones. This article provides a comprehensive study on this issue and develops a practical tool that achieves both good prediction performance and efficiency using only protein sequence information.
Italian hospitals on the web: a cross-sectional analysis of official websites
Authors: Maifredi Giovanni , Orizio Grazia , Bressanelli Maura , Domenighini Serena , Gasparotti Cinzia , Perini Eleonora , Caimi Luigi , Schulz Peter J , Gelatti Umberto
Published: April 2010

Background

Although the use of the Internet for health purposes has increased steadily in the last decade, only a few studies have explored the information provided by the websites of health institutions and no studies on the on-line activities of Italian hospitals have been performed to date. The aim of this study was to explore the characteristics of the contents and the user-orientation of Italian hospital websites.

Methods

The cross-sectional analysis considered all the Italian hospitals with a working website between December 2008 and February 2009. The websites were coded using an ad hoc Codebook, comprising eighty-nine items divided into five sections: technical characteristics, hospital information and facilities, medical services, interactive on-line services and external activities. We calculated a website evaluation score, on the basis of the items satisfied, to compare private (PrHs) and public hospitals, the latter divided into ones with their own website (PubHs-1) and ones with a section on the website of their Local Health Authority (PubHs-2). Lastly, a descriptive analysis of each item was carried out.

Results

Out of the 1265 hospitals in Italy, we found that 419 of the 652 public hospitals (64.3%) and 344 of the 613 PrHs (56.1%) had a working website (p = 0.01). The mean website evaluation score was 41.9 for PubHs-1, 21.2 for PubHs-2 and 30.8 for PrHs (p < 0.001).

Only 5 hospitals out of 763 (< 1%) provided specific clinical performance indicators, such as the nosocomial infection rate or the surgical mortality rates. Regarding interactive on-line services, although nearly 80% of both public and private hospitals enabled users to communicate on-line, less than 18% allowed the reservation of medical services, and only 8 websites (1%) provided a health-care forum.

Conclusions

A high percentage of hospitals did not provide an official website and the majority of the websites found had several limitations. Very few hospitals provided information to increase the credibility of the hospital and user confidence in the institution. This study suggests that Italian hospital websites are more a source of information on admissions and services than a means of communication between user and hospital.
Partnership disengagement from primary community care networks (PCCNs): A qualitative study for a national demonstration project
Authors: Liau Chia-Yi , Lin Cheng-Chieh , Lin Yung-Kai , Lin Blossom Yen-Ju
Published: April 2010

Background

The Primary Community Care Network (PCCN) Demonstration Project, launched by the Bureau of National Health Insurance (BNHI) in 2003, is still in progress. Partnership structures in PCCNs represent both contractual clinic-to-clinic and clinic-to-hospital member relationships of organizational aspects. The partnership structures are the formal relationships between individuals and the total network. Their organizational design aims to ensure effective communication, coordination, and integration across the total network. Previous studies have focused largely on how contractual integration among the partnerships works and on its effects. Few studies, however, have tried to understand partnership disengagement in PCCNs. This study explores why some partnerships in PCCNs disengage.

Methods

This study used a qualitative methodology with semi-structured questions for in-depth interviews. The semi-structured questions were pre-designed to explore the factors driving partnership disengagement. Thirty-seven clinic members who had withdrawn from their PCCNs were identified from the 2003-2005 Taiwan Primary Community Care Network Lists.

Results

Organization/participant factors (extra working time spend and facility competency), network factors (partner collaboration), and community factors (health policy design incompatibility, patient-physician relationship, and effectiveness) are reasons for clinic physicians to withdraw or change their partnerships within the PCCNs.

Conclusions

To strengthen partnership relationships, several suggestions are made, including to establish clinic and hospital member relationships, and to reduce administrative work. In addition, both educating the public about the concept of family doctors and ensuring well-organized national health policies could help health care providers improve the integration processes.
PCBP-1 regulates alternative splicing of the CD44 gene and inhibits invasion in human hepatoma cell line HepG2 cells
Authors: Zhang Tong , Huang Xian-Hong , Dong Lan , Hu Deqing , Ge Changhui , Zhan Yi-Qun , Xu Wang-Xiang , Yu Miao , Li Wei , Wang Xiaohui , Tang Liujun , Li Chang-Yan , Yang Xiao-Ming
Published: April 2010

Background

PCBP1 (or alpha CP1 or hnRNP E1), a member of the PCBP family, is widely expressed in many human tissues and involved in regulation of transcription, transportation process, and function of RNA molecules. However, the role of PCBP1 in CD44 variants splicing still remains elusive.

Results

We found that enforced PCBP1 expression inhibited CD44 variants expression including v3, v5, v6, v8, and v10 in HepG2 cells, and knockdown of endogenous PCBP1 induced these variants splicing. Invasion assay suggested that PCBP1 played a negative role in tumor invasion and re-expression of v6 partly reversed the inhibition effect by PCBP1. A correlation of PCBP1 down-regulation and v6 up-regulation was detected in primary HCC tissues.

Conclusions

We first characterized PCBP1 as a negative regulator of CD44 variants splicing in HepG2 cells, and loss of PCBP1 in human hepatic tumor contributes to the formation of a metastatic phenotype.
Recombinant phospholipase A1 (Ves v 1) from yellow jacket venom for improved diagnosis of hymenoptera venom hypersensitivity
Authors: Seismann Henning , Blank Simon , Cifuentes Liliana , Braren Ingke , Bredehorst Reinhard , Grunwald Thomas , Ollert Markus , Spillner Edzard
Published: April 2010

Background

Hymenoptera venoms are known to cause life-threatening IgE-mediated anaphylactic reactions in allergic individuals. Proper diagnosis of hymenoptera venom allergy using venom extracts is severely affected by molecular cross-reactivities. Although non-glycosylated marker allergens would facilitate the identification of the culprit venom, the major allergen phospholipase A1 (Ves v 1) from yellow jacket venom (YJV) remained unavailable so far.

Methods

Expression of Ves v 1 as wild type and enzymatically inactivated mutant and Ves v 5 in insect cells yielded soluble proteins that were purified via affinity chromatography. Functionality of the recombinant allergens was assessed by enzymatic and biophysical analyses as well as basophil activation tests. Diagnostic relevance was addressed by ELISA-based analyses of sera of YJV-sensitized patients.

Results

Both major allergens Ves v 1 and Ves v 5 could be produced in insect cells in secreted soluble form. The recombinant proteins exhibited their particular biochemical and functional characteristics and were capable for activation of human basophils. Assessment of IgE reactivity of sera of YJV-sensitized and double-sensitized patients emphasised the relevance of Ves v 1 in hymenoptera venom allergy. In contrast to the use of singular molecules the combined use of both molecules enabled a reliable assignment of sensitisation to YJV for more than 90% of double-sensitised patients.

Conclusions

The recombinant availability of Ves v 1 from yellow jacket venom will contribute to a more detailed understanding of the molecular and allergological mechanisms of insect venoms and may provide a valuable tool for diagnostic and therapeutic approaches in hymenoptera venom allergy.
A novel serum-free medium for the expansion of human mesenchymal stem cells
Authors: Chase Lucas G , Lakshmipathy Uma , Solchaga Luis A , Rao Mahendra S , Vemuri Mohan C
Published: April 2010

Introduction

Human multipotent mesenchymal stem cell (MSC) therapies are being tested clinically for a variety of disorders, including Crohn's disease, multiple sclerosis, graft-versus-host disease, type 1 diabetes, bone fractures, and cartilage defects. However, despite the remarkable clinical advancements in this field, most applications still use traditional culture media containing fetal bovine serum. The ill-defined and highly variable nature of traditional culture media remains a challenge, hampering both the basic and clinical human MSC research fields. To date, no reliable serum-free medium for human MSCs has been available.

Methods

In this study, we developed and tested a serum-free growth medium on human bone marrow-derived MSCs through the investigation of multiple parameters including primary cell isolation, multipassage expansion, mesoderm differentiation, cellular phenotype, and gene-expression analysis.

Results

Similar to that achieved with traditional culture medium, human MSCs expanded in serum-free medium supplemented with recombinant human platelet-derived growth factor-BB (PDGF-BB), basic fibroblast growth factor (bFGF), and transforming growth factor (TGF)-β1 showed extensive propagation with retained phenotypic, differentiation, and colony-forming unit potential. To monitor global gene expression, the transcriptomes of bone marrow-derived MSCs expanded under serum-free and serum-containing conditions were compared, revealing similar expression profiles. In addition, the described serum-free culture medium supported the isolation of human MSCs from primary human marrow aspirate with continual propagation.

Conclusions

Although the described serum-free MSC culture medium is not free of xenogeneic components, this medium provides a substitute for serum-containing medium for research applications, setting the stage for future clinical applications.
Adipose tissue macrophages: their role in adipose tissue remodeling
Authors: Suganami Takayoshi , Ogawa Yoshihiro
Published: April 2010

This review summarizes the role of macrophages in adipose tissue remodeling, particularly focusing on the paracrine loop between adipocytes and macrophages.

The adipose tissue secretes a large number of bioactive substances, adipocytokines, which may be involved in a variety of physiologic and pathologic processes. Unbalanced production of pro- and anti-inflammatory adipocytokines seen in visceral fat obesity contributes critically to the development of the metabolic syndrome. Evidence has accumulated indicating that obesity is associated with a state of chronic, low-grade inflammation, suggesting that inflammation may be a potential mechanism, whereby obesity leads to insulin resistance. Indeed, obese adipose tissue is characterized by adipocyte hypertrophy, followed by increased angiogenesis, immune cell infiltration, extracellular matrix overproduction, and thus, increased production of proinflammatory adipocytokines during the progression of chronic inflammation. The dynamic change found in the adipose tissue can be referred to as “adipose tissue remodeling,” in which stromal cells change dramatically in number and cell type during the course of obesity. Among stromal cells, infiltration of macrophages in the adipose tissue precedes the development of insulin resistance in animal models, suggesting that they are crucial for obesity-related adipose tissue inflammation. We have demonstrated that a paracrine loop involving saturated fatty acids and TNF-α derived from adipocytes and macrophages, respectively, aggravates obesity-induced adipose tissue inflammation. Notably, saturated fatty acids, which are released from hypertrophied adipocytes via the macrophage-induced lipolysis, serve as a naturally occurring ligand for TLR4 complex, thereby activating macrophages. Understanding the molecular mechanism underlying adipose tissue remodeling may lead to the identification of novel, therapeutic strategies to prevent or treat obesity-induced adipose tissue inflammation.
Release of IL-12 by dendritic cells activated by TLR ligation is dependent on MyD88 signaling, whereas TRIF signaling is indispensable for TLR synergy
Authors: Krummen Mathias , Balkow Sandra , Shen Limei , Heinz Stefanie , Loquai Carmen , Probst Hans-Christian , Grabbe Stephan
Published: April 2010

Synergistic activation of dendritic cells by combinations of TLR ligands requires both MyD88- and TRIF-dependent signaling.

Recently, it has been shown that certain combinations of TLR ligands act in synergy to induce the release of IL-12 by DCs. In this study, we sought to define the critical parameters underlying TLR synergy. Our data show that TLR ligands act synergistically if MyD88- and TRIF-dependent ligands are combined. TLR4 uses both of these adaptor molecules, thus activation via TLR4 proved to be a synergistic event on its own. TLR synergy did not affect all aspects of DC activation but enhanced primarily the release of certain cytokines, particularly IL-12, whereas the expression of costimulatory molecules remained unchanged. Consequently, synergistic activation of DC did not affect their ability to induce T cell proliferation but resulted in TH1-biased responses in vitro and in vivo. Furthermore, we examined the impact of TLR ligand combinations on primary DC in vitro but observed only modest effects with a combination of CpG + Poly (I:C). However, noticeable synergy in terms of IL-12 production by DCs was detectable in vivo after systemic administration of CpG + Poly (I:C). Finally, we show that synergy is partially dependent on IFNAR signaling but does not require the release of IFNs to the enviroment, suggesting an autocrine action of type I IFNs.
Differential polarization of alveolar macrophages and bone marrow-derived monocytes following chemically and pathogen-induced chronic lung inflammation
Authors: Redente Elizabeth F , Higgins David M , Dwyer-Nield Lori D , Orme Ian M , Gonzalez-Juarrero Mercedes , Malkinson Alvin M
Published: April 2010

Alveolar macrophages undergo similar polarization to chemically and pathogen-induced chronic lung inflammation, but the phenotype of bone marrow-derived monocytes varies between inflammations.

Alveolar macrophages and BDMCs undergo sequential biochemical changes during the chronic inflammatory response to chemically induced lung carcinogenesis in mice. Herein, we examine two chronic lung inflammation models—repeated exposure to BHT and infection with Mycobacterium tuberculosis—to establish whether similar macrophage phenotype changes occur in non-neoplastic pulmonary disease. Exposure to BHT or M. tuberculosis results in pulmonary inflammation characterized by an influx of macrophages, followed by systemic effects on the BM and other organs. In both models, pulmonary IFN-γ and IL-4 production coincided with altered polarization of alveolar macrophages. Soon after BHT administration or M. tuberculosis infection, IFN-γ content in BALF increased, and BAL macrophages became classically (M1) polarized, as characterized by increased expression of iNOS. As inflammation progressed in both models, the amount of BALF IFN-γ content and BAL macrophage iNOS expression decreased, and BALF IL-4 content and macrophage arginase I expression rose, indicating alternative/M2 polarization. Macrophages present in M. tuberculosis-induced granulomas remained M1-polarized, implying that these two pulmonary macrophage populations, alveolar and granuloma-associated, are exposed to different activating cytokines. BDMCs from BHT-treated mice displayed polarization profiles similar to alveolar macrophages, but BDMCs in M. tuberculosis-infected mice did not become polarized. Thus, only alveolar macrophages in these two models of chronic lung disease exhibit a similar progression of polarization changes; polarization of BDMCs was specific to BHT-induced pulmonary inflammation, and polarization of granuloma macrophages was specific to the M. tuberculosis infection.
Dual targeting of CCR2 and CCR5: therapeutic potential for immunologic and cardiovascular diseases
Authors: Zhao Qihong
Published: April 2010

This review presents evidence that dual targeting of CCR2 and CCR5 has greater therapeutic potential than targeting either receptor alone.

A cardinal feature of inflammation is the tissue recruitment of leukocytes, a process that is mediated predominantly by chemokines via their receptors on migrating cells. CCR2 and CCR5, two CC chemokine receptors, are important players in the trafficking of monocytes/macrophages and in the functions of other cell types relevant to disease pathogenesis. This review provides a brief overview of the biological actions of CCR2 and CCR5 and a comprehensive summary of published data that demonstrate the involvement of both receptors in the pathogenesis of immunologic diseases (RA, CD, and transplant rejection) and cardiovascular diseases (atherosclerosis and AIH). In light of the potential for functional redundancy of chemokine receptors in mediating leukocyte trafficking and the consequent concern over insufficient efficacy offered by pharmacologically inhibiting one receptor, this review presents evidence supporting dual targeting of CCR2 and CCR5 as a more efficacious strategy than targeting either receptor alone. It also examines potential safety issues associated with such dual targeting.
Distinct roles of complement receptor 3, Dectin-1, and sialic acids in murine macrophage interaction with Histoplasma yeast
Authors: Lin Jr-Shiuan , Huang Juin-Hua , Hung Li-Yin , Wu Sheng-Yang , Wu-Hsieh Betty A
Published: April 2010

CR3 on primary macrophage participates in phagocytosis of Histoplasma yeast and collaborates with dectin-1 in macrophage cytokine response to the fungus.

The yeast cells of dimorphic fungal pathogen Histoplasma reside primarily within the macrophages of an infected host; the interaction between the yeast and macrophage has a profound impact on host defense against the fungus. We used blocking antibodies and saccharides to identify the receptors that participate in the phagocytosis of and the cytokine response to Histoplasma. The phagocytosis and cytokine response results show that sialic acids on the macrophages were involved in the interaction between macrophages and Histoplasma. CR3, although not the only receptor involved, was responsible for phagocytosis and cytokine response. It is unclear which receptors other than CR3 are responsible for phagocytosis, but we did rule out the participation of TLR2, TLR4, MR, DC-SIGN/SIGNR1, FcγR, VLA-5, and Dectin-1. Even though Dectin-1 did not participate in phagocytosis, it collaborated with CR3 in the cytokine response to Histoplasma, suggesting that in the presence of phagocytic receptors, Histoplasma triggers cytokine signals through Dectin-1. Moreover, macrophage phagocytosis of and cytokine response to Histoplasma are Syk kinase-dependent. Our study delineated the distinct roles of CR3, Dectin-1, and sialic acids in the interaction with Histoplasma and suggested that multiple receptor use might be important to host defense against Histoplasma.
Robust design optimization of the McPherson suspension system with consideration of a bush compliance uncertainty
Authors: Kang D-O , Heo S-J , Kim M-S
Published: April 2010

A robust suspension system design optimization, which takes into account the kinematic behaviours influenced by bush compliance uncertainty, is presented. The design variables are the positions of the joints, and the random constant is the bush stiffness with uncertainty. The design goals for these kinematic behaviours are typically represented as deviations over the wheel movements. It can be very difficult to evaluate the analytical design sensitivity because the deviation is defined by using the maximum and minimum values over the parameter interval. To avoid the difficulty, this study introduces a metamodel technique. The sample variances for the design goals are approximated from metamodels. In addition, a sequential approximation optimization technique is used to solve a robust design problem for the suspension system. The robust design problem has 18 design variables and 18 random constants with uncertainty. The proposed approach required only 189 evaluations until it converged. The selected design reduced the maximum deviations in the toe and camber angles by 72 per cent and 50 per cent respectively, and their variances by 90 per cent, while satisfying the constraints of changes in the toe angle, camber angle, and front-to-rear change in the wheel centre.
Design of a vision-based autonomous path-tracking control system and experimental validation
Authors: Shin D-H , Joo B-Y
Published: April 2010

This paper describes an automated path-tracking system using a vision sensor. A lateral control law for path tracking is especially emphasized which is developed by using back-stepping control design methodology. To establish the proposed control system, the lateral offset to the reference path, the heading angle of the vehicle relative to the tangent line to the path, and the path curvature are required. Those inputs to the controller have been calculated through a Kalman filter which is frequently utilized for the purpose. Lane mark detection has been achieved in an electronic control unit platform with a vision sensor. The yaw rate and side-slip angle also needed in the controller are estimated by the observer. To demonstrate the performances of the proposed controller at different speeds, an experiment has been conducted on a proving ground having a straight section and a curved section with a curvature of about 260m.
Comparison of the indicated work outputs, idle stabilities, and heat release characteristics of a direct-injection diesel engine operating cold at two compression ratios
Authors: MacMillan D J , La Rocca A , Shayler P J , Murphy M , Pegg I , Morris T
Published: April 2010

A reduction in the compression ratio can adversely affect the cold-start and idling performance of diesel engines. The problems and potential solutions have been investigated. Studies have been carried out to compare the indicated performances and heat release characteristics of a direct-injection diesel engine during low-speed cold operation at compression ratios of 18.4:1 and 15.4:1. The test engine was a naturally aspirated single-cylinder design with a swept volume of 0.5l. Tests covered start temperatures between 10°C and 20°C. At around 300r/min, the indicated work output was higher at the lower compression ratio as a result of lower blow-by, and the cycle-by-cycle stabilities of the heat release and work output were similar at both compression ratios. The cycle-by-cycle stability deteriorated with increasing engine speed. At 1000r/min idling conditions, the stability was relatively poor and was worse for the low-compression-ratio case. At the high compression ratio, the cycle-by-cycle stability was improved by introducing multiple pilot injections and using metallic glow plugs operating at about 850°C. At the low compression ratio, improvements in stability could not be achieved without switching to glow plugs operating at about 1100°C.
Experimental research on the effect of structural parameters on the governing characteristics of a pulley-drive, continuously variable transmission
Authors: Zhu C-C , Liu H-J , Tian J-J , Xiao Q , Du X-S
Published: April 2010

Because of its incomparable advantages over other transmissions especially in some specific conditions, rubber-V-belt, continuously variable transmissions (CVTs) have been extensively applied in low-power vehicles, such as scooters and snowmobiles. The main structural parameters of a CVT evidently affect the driving performance of the vehicle. The effect of one main structural parameter, namely the masses of the flyweights utilized, on the governing characteristics of the CVT is studied, and the mechanism of the effect is explained. First, a mechanical analysis of the drive pulley and the driven pulley of a rubber-belt CVT employed on a snowmobile is conducted. Through the theoretical analysis, the mathematical model of the system running in a steady state is built. Then the principle of parameter optimization, the running resistance of the vehicle, as well as the external characteristics of the gasoline engine applied in the snowmobile are investigated. Finally, experimental research on the structural tuning based on the building of a CVT test rig is carried out. Since it is difficult to change the parameters of some components such as the torque cam and the profile line of the flyweights, the masses of the flyweights are considered as the unique design variables, and different regulating characteristics of the available groups are obtained. Different applications accordingly require corresponding structural design schemes. The experimental results show that the proposed parameter-tuning principle is theoretically correct and practically feasible, which makes it useful for guidance in designing the CVT, as well as the whole driveline.
Development of an exhaust gas recirculation strategy for an acetylene-fuelled homogeneous charge compression ignition engine
Authors: Sudheesh K , Mallikarjuna J M
Published: April 2010

This paper deals with experimental investigations carried out to develop an exhaust gas recirculation (EGR) strategy for an acetylene-fuelled homogeneous charge compression ignition (HCCI) engine. This study involves an analysis of the external inlet charge heating, the use of a mix of hot EGR and cool EGR to extend the load range, and the performance of the engine in the acetylene HCCI mode. First, experiments are conducted on a single-cylinder engine in the acetylene HCCI mode with external electrical heating at different load conditions, and the best inlet charge temperatures at each load condition are obtained. Second, hot EGR or a mix of hot EGR and cool EGR (i.e. the EGR strategy) is used to reduce or eliminate external charge heating and to extend the upper load limit, or to improve the brake thermal efficiency. In both cases, the engine performance is compared with that of the conventional diesel compression ignition (CI) mode. It is found that with EGR, above 25 per cent of load, the upper load limit at different inlet charge temperatures increases by about 16 28 per cent without any external charge heating. Below 25 per cent of load, the electrical heating at different inlet charge conditions is reduced by about 67–87 per cent. The brake thermal efficiency increases by 5–24 per cent under all the load conditions and it is comparable with that in the conventional CI mode. In the HCCI mode, nitrogen oxide levels are less than 20ppm. Smoke levels are always lower than 0.1 Bosch smoke unit. Hydrocarbon and carbon monoxide emissions are relatively higher than for the conventional CI mode.
Modified bowl geometry for cluster nozzles in direct-injection diesel engines
Authors: Won H W , Peters N
Published: April 2010

A combination of high-pressure injection and small orifices will be one of the strategies to achieve lean combustion. However, equispaced small orifices tend to increase soot under high-load conditions because the spray penetration becomes exceedingly inadequate. For this reason, the cluster concept was chosen as the means to realize lean combustion. To make the use of clusters in a diesel engine feasible, a significant redesign of the typical in-cylinder geometry would probably be required to promote efficient air utilization. The new combustion chamber was designed with a smaller diameter and deeper bowl. It is expected to improve fuel—air mixing by better spray guidance. The study identifies the aspects of combustion and pollution formation that are affected by mixing processes and offers guidance for better matching of the piston geometry with the spray plume geometry for enhanced mixing. Various clusters were investigated to achieve variation in the injection timing for different test points in the original piston bowl chamber and the new bowl chamber, and the results are compared with those for a conventional nozzle. The cluster with the best results for smoke emissions in the first set of tests was also tested for different swirl ratios and different nozzle protrusion lengths.
Effect of the dwell angle of split injection in a single-cylinder optical diesel engine
Authors: Díez Á , Zhao H
Published: April 2010

This study investigates the effects of split-injection strategies with high levels of exhaust gas recirculation on the combustion performance and emissions in a single-cylinder direct-injection optical diesel engine. The engine is equipped with high-pressure common-rail fuel injection and designed to provide optical access through the piston window and side windows. The experiments were carried out at a relatively high engine speed of 2000r/min for an optical engine and in-cylinder conditions matched to a multiple-cylinder engine through boost and intake charge heating. High-speed combustion imaging, two-colour temperature, and soot concentration measurements were carried out in conjunction with in-cylinder pressure and heat release analysis and exhaust emissions.

The results at two dwell angles and different injection timings are presented and analysed in this paper. The effects of the dwell angle and fuel injection timings on fuel air mixing, combustion, soot formation, and emission are identified and discussed.
Numerical and experimental research of stall inception on subsonic axial-flow compressor rotor
Authors: Lu J-L , Chu W , Peng K
Published: April 2010

Three-dimensional flow simulation and blade tip high-response static pressure measurements were performed on an isolated subsonic compressor rotor to gain more insight into the stall inception mechanism of the compressors. The Navier—Stokes solver, EURANUS, was used for computation. The steady-state flow solution was achieved at the convergence of a four-stage explicit Runge—Kutta integration scheme. The time-dependent calculation was implemented in the implicit dual time stepping scheme, which allowed for the solution of a steady-state problem at each physical time step. The high-response static pressure was measured using five Kulite sensors installed on the casing. The data acquisition frequency was 100 kHz. The recorded data were later analysed using wavelet analysis method.

Correlating the simulation result and the measurement result, it was shown that as the compressor was approaching the near stall (NS) condition, the tip leakage vortex dissipation and shedding became violent. The shedding or dissipated flow structures would consequently scatter around the blade tip passage, which formed the initial onset of stall disturbances. These scattered vortexes would finally lead to compressor stall as they hit and merge with each other into low-frequency disturbance of significant size and energy. A stall pre-alarming method based on the monitoring of the low-frequency spectrum power at the NS condition was also suggested by this study.
A technology for scheduling of data exchange over bus with centralized control in onboard avionics systems
Authors: Balashov V V , Balakhanov V A , Kostenko V A , Smeliansky R L , Kokarev V A , Shestov P E
Published: April 2010

In this paper, the problem of automatic scheduling of data exchange over a channel with centralized control in real-time avionics (RTA) systems is addressed. Examples of such channels are MIL STD-1553B multiplex data bus and Fibre Channel FC-AE-1553. Scheduling algorithms implementing greedy strategy and ant colony method are presented and evaluated experimentally. These algorithms support customization for specific requirements of the target onboard RTA system. Results of experimental evaluation demonstrate that the ant colony algorithm outperforms greedy algorithms on most of the considered classes of input data, with realistic technological requirements to data exchange. The proposed technology for data exchange scheduling is implemented in a tool system. Two case studies of industrial application of the system to the development of onboard real-time systems are described.
A comparative study of ultrasonic direct contact, immersion, and layer resonance methods for assessment of enamel thickness in teeth
Authors: Dwyer-Joyce R S , Goodman M A , Lewis R
Published: April 2010

Wear of dental enamel is a growing problem, but is clinically difficult to diagnose and monitor. An accurate and easy-to-use non-destructive method for the measurement of enamel thickness would be useful for early diagnosis of enamel loss and for monitoring progression. Ultrasound has been identified by several researchers as a potential tool suitable for enamel thickness measurement. However, in vitro studies have shown that while the method is feasible, it suffers from wide variability. The methods proposed to date rely on the measurement of the time of flight of an ultrasonic pulse through the enamel layer. This requires the operator to locate the enamel-dentine junction. In this work, three methods are evaluated to try to reduce this variability and to investigate some practicalities of the approach. Time-of-flight methods using both contact and immersion transducers were used. Immersion transducers gave the most accurate results, within 10-15 per cent of values deduced from tooth sections, but would be harder to arrange for in vivo measurements. Preliminary studies have also shown that it is possible to achieve a resonance in the enamel layer and to measure thickness that way. While this approach needs further experimental refinement, it has the potential to be used for much thinner enamel layer thicknesses.
Fourier transform infrared and ultraviolet-visible investigation of swift heavy 100 MeV Ag-ion- and 75 MeV oxygen-ion-irradiated polyvinylidene fluoride thin films
Authors: Rana D S , Chaturvedi D K , Quamara J K
Published: April 2010

Polyvinylidene fluoride (PVDF) polymer films (9, 12, and 20 μm) were irradiated with 100 MeV Ag ion (fluence: 1.875×1011 ions/cm2) and 75 MeV oxygen ion (fluences: 5.625×1011 and 5.675×1012 ions/cm2) using the PELLETRON facility at the Inter University Accelerator Centre, New Delhi, to study swift heavy ion (SHI) irradiation effects in thin films. The change in chemical, optical, and structural properties was analysed by comparing Fourier transform infrared (FTIR) and ultraviolet (UV)-visible spectra of pristine and irradiated films. The FTIR spectra show no major change in characteristic bands on irradiation, except that some weak bands appear because of the evolution of volatile species, unsaturated bond formation, decomposition of the free radicals, and subsequent cross-linking. The spectra of the irradiated films show some broadening and a decrease in intensity in characteristic bands when compared with the pristine samples. The FTIR results indicate that the overall chemical structure of PVDF is stable under SHI irradiation.

The UV-visible absorption spectra of irradiated samples reveal hyperchromic shift, bathochromic shift, and hypsochromic shift. The spectra also estimate the direct optical band gap around 3.6 eV. The band gap decreases on irradiation, and the decrease is dependent on ion beam and fluence rate. The present study opens up the scope for the applicability of SHI-irradiated PVDF thin films as microsensors and actuators.
Characterization of Ti-CN-a: C films prepared by pulsed-dc bias sputtering
Authors: Bulbul F , Efeoglu I
Published: April 2010

The incapable side of diamond-like carbon films is low adhesion, resulting from high internal stress. The incorporation of buffer layers into the coating structure to relieve stress and to allow crack energy dissipation by plastic deformation in the crack tip is an effective route for improving toughness. Although this approach will result in a partly decreased coating hardness, the gain in tribological properties is more preferred for many applications. In graded coatings, design and joining of the functional regions including sharp interfaces between layers are very important. The desirable properties can provide only through appropriate transition regions produced by using appropriate deposition methods. In this study, Ti-CN-a:C films were deposited on AISI M2 steel substrates by closed-field unbalanced magnetron sputtering using pulsed-dc biasing, and hardness, crystallography, wear, and adhesion properties of the film were investigated. Accordingly, Ti-CN-a:C films grown exhibited an increase of about 30 per cent in hardness according to that of the substrate and low (μ ∼ 0.1) and stable friction and good adhesion ( Lc=43 N), whereas the crystallographic development of the film was amorphous. These properties obtained were attributed to using of CN transient layer and pulsed-dc magnetron sputtering technology.
Three-dimensional numerical analysis of hydrodynamic characteristics of axial groove journal bearings running with ferrofluids under magnetic field
Authors: Nejad Y Sheikh , Nassab S A Gandjalikhan
Published: April 2010

In this study, hydrodynamic characteristics of finite length journal bearings running with incompressible laminar flow under magnetic field are investigated. Ferrofluid as a lubricant contains nanoparticles of magnetite (Fe3O4). The analysis is based on the numerical solution of the full Navier-Stokes equations using computational fluid dynamics techniques. Considering the complexity of the physical geometry, conformal mapping is used to generate an orthogonal grid, and the governing equations are transformed in the computational domain. Discretized forms of the transformed equations are obtained by the control volume method and solved by the SIMPLE algorithm. Results indicated that when compared with the conventional lubricant, the ferrofluid as a lubricant enhances the hydrodynamic characteristics of journal bearings and provides a higher load capacity. Besides, it was found that the other bearing characteristics are considerably affected by the applied magnetic field.
An assessment of steering drift during braking: A comparison between finite-element and rigid body analyses
Authors: Mirza N , Hussain K , Day A J , Klaps J
Published: April 2010

A vehicle that deviates laterally from its intended path of travel when the brakes are applied is considered to demonstrate ‘instability’ in the form of an unexpected and undesirable response to the driver input. Even where the magnitude of lateral displacement of the vehicle is small (i.e. ‘drift’ rather than ‘pull’) such a condition would be considered unacceptable by manufacturers and customers.

Steering ‘drift’ during braking can be caused by several factors, some of which relate to vehicle design and others to external influences such as road conditions. The study presented here examines the causes and effects of steering drift during straight-line braking. A comparative analysis is made between two types of vehicle model: one built with rigid suspension components and the other with flexible components. In both the cases, the vehicle behaviour is simulated during braking in a straight line, and responses including lateral acceleration, yaw rate, and lateral displacement of the vehicle are predicted and analysed under fixed steering control. Suspension/steering geometry characteristics, namely toe steer and caster angle, have been studied to understand how the effect of variations in these parameters differs in models with rigid or flexi-ble components drift during straight-line braking. Results from both vehicle models show that differences between rigid and flexible components can affect the predicted steering drift propensity. The differences between the two models have emphasized the importance of using flexible (compliant) components in vehicle handling simulations to achieve better correlation between prediction and experiment.