bluuebunny/crossref_metadata_2025 huggingface dataset:
Laser microdissection of conifer stem tissues: Isolation and analysis of high quality RNA, terpene synthase enzyme activity and terpenoid metabolites from resin ducts and cambial zone tissue of white spruce (Picea glauca)
Authors: Abbott Eric , Hall Dawn , Hamberger Björn , Bohlmann Jörg
Published: June 2010

Background

Laser microdissection (LMD) has been established for isolation of individual tissue types from herbaceous plants. However, there are few reports of cell- and tissue-specific analysis in woody perennials. While microdissected tissues are commonly analyzed for gene expression, reports of protein, enzyme activity and metabolite analysis are limited due in part to an inability to amplify these molecules. Conifer stem tissues are organized in regular patterns with xylem, phloem and cortex development controlled by the activity of the cambial zone (CZ). Defense responses of conifer stems against insects and pathogens involve increased accumulation of terpenoids in cortical resin ducts (CRDs) and de novo formation of traumatic resin ducts from CZ initials. These tissues are difficult to isolate for tissue-specific molecular and biochemical characterization and are thus good targets for application of LMD.

Results

We describe robust methods for isolation of individual tissue-types from white spruce (Picea glauca) stems for analysis of RNA, enzyme activity and metabolites. A tangential cryosectioning approach was important for obtaining large quantities of CRD and CZ tissues using LMD. We report differential expression of genes involved in terpenoid metabolism between CRD and CZ tissues and in response to methyl jasmonate (MeJA). Transcript levels of β-pinene synthase and levopimaradiene/abietadiene synthase were constitutively higher in CRDs, but induction was stronger in CZ in response to MeJA. 3-Carene synthase was more strongly induced in CRDs compared to CZ. A differential induction pattern was observed for 1-deoxyxyulose-5-phosphate synthase, which was up-regulated in CRDs and down-regulated in CZ. We identified terpene synthase enzyme activity in CZ protein extracts and terpenoid metabolites in both CRD and CZ tissues.

Conclusions

Methods are described that allow for analysis of RNA, enzyme activity and terpenoid metabolites in individual tissues isolated by LMD from woody conifer stems. Patterns of gene expression are demonstrated in specific tissues that may be masked in analysis of heterogenous samples. Combined analysis of transcripts, proteins and metabolites of individual tissues will facilitate future characterization of complex processes of woody plant development, including periodic stem growth and dormancy, cell specialization, and defense and may be applied widely to other plant species.
Sex-differential genetic effect of phosphodiesterase 4D (PDE4D) on carotid atherosclerosis
Authors: Liao Yi-Chu , Lin Hsiu-Fen , Guo Yuh-Cherng , Yu Ming-Lung , Liu Ching-Kuan , Juo Suh-Hang Hank
Published: June 2010

Background

The phosphodiesterase 4D (PDE4D) gene was reported as a susceptibility gene to stroke. The genetic effect might be attributed to its role in modulating the atherogenic process in the carotid arteries. Using carotid intima-media thickness (IMT) and plaque index as phenotypes, the present study sought to determine the influence of this gene on subclinical atherosclerosis.

Methods

Carotid ultrasonography was performed on 1013 stroke-free subjects who participated in the health screening programs (age 52.6 ± 12.2; 47.6% men). Genotype distribution was compared among the high-risk (plaque index ≥ 4), low-risk (index = 1-3), and reference (index = 0) groups. We analyzed continuous IMT data and further dichotomized IMT data using mean plus one standard deviation as the cutoff level. Because the plaque prevalence and IMT values displayed a notable difference between men and women, we carried out sex-specific analyses in addition to analyzing the overall data. Rs702553 at the PDE4D gene was selected because it conferred a risk for young stroke in our previous report. Previous young stroke data (190 cases and 211 controls) with an additional 532 control subjects without ultrasonic data were shown as a cross-validation for the genetic effect.

Results

In the overall analyses, the rare homozygote of rs702553 led to an OR of 3.1 (p = 0.034) for a plaque index ≥ 4. When subjects were stratified by sex, the genetic effect was only evident in men but not in women. Comparing male subjects with plaque index ≥ 4 and those with plaque index = 0, the TT genotype was over-represented (27.6% vs. 13.4%, p = 0.008). For dichotomized IMT data in men, the TT genotype had an OR of 2.1 (p = 0.032) for a thicker IMT at the common carotid artery compared with the (AA + AT) genotypes. In women, neither IMT nor plaque index was associated with rs702553. Similarly, SNP rs702553 was only significant in young stroke men (OR = 1.8, p = 0.025) but not in women (p = 0.27).

Conclusions

The present study demonstrates a sex-differential effect of PDE4D on IMT, plaque index and stroke, which highlights its influence on various aspects of atherogenesis.
Epigenetic alterations differ in phenotypically distinct human neuroblastoma cell lines
Authors: Yang Qiwei , Tian Yufeng , Ostler Kelly R , Chlenski Alexandre , Guerrero Lisa J , Salwen Helen R , Godley Lucy A , Cohn Susan L
Published: June 2010

Background

Epigenetic aberrations and a CpG island methylator phenotype have been shown to be associated with poor outcomes in children with neuroblastoma (NB). Seven cancer related genes (THBS-1, CASP8, HIN-1, TIG-1, BLU, SPARC, andHIC-1) that have been shown to have epigenetic changes in adult cancers and play important roles in the regulation of angiogenesis, tumor growth, and apoptosis were analyzed to investigate the role epigenetic alterations play in determining NB phenotype.

Methods

Two NB cell lines (tumorigenic LA1-55n and non-tumorigenic LA1-5s) that differ in their ability to form colonies in soft agar and tumors in nude mice were used. Quantitative RNA expression analyses were performed on seven genes in LA1-5s, LA1-55n and 5-Aza-dC treated LA1-55n NB cell lines. The methylation status aroundTHBS-1, HIN-1, TIG-1andCASP8promoters was examined using methylation specific PCR. Chromatin immunoprecipitation assay was used to examine histone modifications along theTHBS-1promoter. Luciferase assay was used to determineTHBS-1promoter activity. Cell proliferation assay was used to examine the effect of 5-Aza-dC on NB cell growth. The soft agar assay was used to determine the tumorigenicity.

Results

Promoter methylation values forTHBS-1,HIN-1,TIG-1, andCASP8were higher in LA1-55n cells compared to LA1-5s cells. Consistent with the promoter methylation status, lower levels of gene expression were detected in the LA1-55n cells. Histone marks associated with repressive chromatin states (H3K9Me3, H3K27Me3, and H3K4Me3) were identified in theTHBS-1promoter region in the LA1-55n cells, but not the LA1-5s cells. In contrast, the three histone codes associated with an active chromatin state (acetyl H3, acetyl H4, and H3K4Me3) were present in theTHBS-1promoter region in LA1-5s cells, but not the LA1-55n cells, suggesting that an accessible chromatin structure is important forTHBS-1expression. We also show that 5-Aza-dC treatment of LA1-55n cells alters the DNA methylation status and the histone code in theTHBS-1promoter modifies cell morphology, and inhibits their ability to form colonies in soft agar.

Conclusion

Our results suggest that epigenetic aberrations contribute to NB phenotype, and that tumorigenic properties can be inhibited by reversing the epigenetic changes with 5-Aza-dC.
Women's preference for cesarean delivery and differences between Taiwanese women undergoing different modes of delivery
Authors: Chu Kuei-Hui , Tai Chen-Jei , Hsu Chun-Sen , Yeh Mei-Chiang , Chien Li-Yin
Published: June 2010

Background

The rate of cesarean delivery was 35% in 2007 in Taiwan. It is unclear how many of the cesarean deliveries were without medical indications. Women's preference for cesarean delivery during their course of pregnancy has rarely been studied and therefore our objectives were to examine rate of cesarean deliveries without medical indications, to explore women's preference for cesarean delivery as their gestation advances, and to compare background and perinatal factors among women who underwent different modes of delivery in Taiwan.

Methods

This prospective study applied a longitudinal design. The study participants were 473 women who received prenatal care at four hospitals in Taipei and answered structured questionnaires at 20 to 24 weeks of pregnancy, 34 to 36 weeks of pregnancy, and 5 to 7 weeks after delivery.

Results

Of the 151 women (31.9%) who had cesarean deliveries, 19.9% were without medical indication. Three indications: malpresentation, prior cesarean section, and dysfunctional labor together accounted for 82.6% of cesarean section with medical indications. The prevalence of maternal preference for cesarean delivery was found to be 12.5% and 17.5% during the second and third trimester, respectively. Of the women who preferred cesarean delivery during the second trimester, 93.2% eventually had a cesarean delivery. Women who were older, with older spouses, and who had health problems before or during pregnancy were more likely to have cesarean deliveries.

Conclusions

About 20% of cesarean deliveries were without medical indications. Women's preference for cesarean delivery during the second trimester predicts subsequent cesarean delivery. Counseling regarding mode of delivery should be offered early in pregnancy, especially for women who are older or with older spouses, have health problems, or had a prior cesarean section.
Preferences for benefit packages for community-based health insurance: an exploratory study in Nigeria
Authors: Onwujekwe Obinna , Onoka Chima , Uguru Nkoli , Nnenna Tasie , Uzochukwu Benjamin , Eze Soludo , Kirigia Joses , Petu Amos
Published: June 2010

Background

It is important that community-based health insurance (CBHI) schemes are designed in such a way as to ensure the relevance of the benefit packages to potential clients. Hence, this paper provides an understanding of the preferred benefit packages by different economic status groups as well as urban and rural dwellers for CBHI in Southeast Nigeria.

Methods

The study took place in rural, urban and semi-urban communities of south-east Nigeria. A questionnaire was used to collect information from 3070 randomly picked household heads. Focus group discussions were used to collect qualitative data. Data was examined for links between preferences for benefit packages with SES and geographic residence of the respondents.

Results

Respondents in the rural areas and in the lower SES preferred a comprehensive benefit package which includes all inpatient, outpatient and emergencies services, while those in urban areas as well as those in the higher SES group showed a preference for benefit packages which will cover only basic disease control interventions.

Conclusion

Equity concerns in preferences for services to be offered by the CBHI scheme should be addressed for CBHI to succeed in different contexts.
Summary of worldwide pediatric malignancies reported after exposure to etanercept
Authors: McCroskery Peter , Wallace Carol A , Lovell Daniel J , Stryker Scott , Chernyukhin Nataliya , Blosch Consuelo , Zack Debra J
Published: June 2010

Background

Concerns have been raised about a potential link between the use of TNF inhibitors and development of malignancy in the pediatric population. We examined the worldwide experience of etanercept use in pediatric patients and the occurrence of malignancies as reported from clinical trials, registry studies, post-marketing surveillance, and published scientific literature.

Methods

All reports of "malignancy" in pediatric patients (including subjects who received etanercept before age 18 and developed a malignancy before age 22) were collected from the etanercept clinical trials database and global safety database using the Medical Dictionary for Regulatory Activities (MedDRA; v12.0) standardized MedDRA query "Malignancies" from 1998 to August 2009. Cases were collected irrespective of treatment indication. All cases were included regardless of exposure to other TNF blockers or other biologics and whether the other exposure was before or after etanercept.

Results

A total of 18 potential malignancies were identified: 4 leukemias, 7 lymphomas, and 7 solid tumors. Three of the 18 malignancies remain unconfirmed. No malignancies were reported from clinical trials or the open-label extension studies in any indication in children.

Conclusion

The data suggest that there does not appear to be an increased risk of malignancy overall with the use of etanercept. Among etanercept-exposed patients aged 4 to 17 years, the estimated worldwide and US reporting rates for lymphoma were approximately 0.01 per 100 patient-years (1 in 10,000 pt-yrs). While the reported rate of lymphoma is higher in pediatric patients treated with etanercept than in normal children, the expected rate of lymphoma in biologic naïve JIA patients is currently unknown. The risk of TNF inhibitors in the development of malignancies in children and adolescents is difficult to assess because of the rarity of malignant events, the absence of knowledge of underlying frequency of leukemia and lymphoma in JIA, and the confounding use of concomitant immunosuppressive medications.
Differential activity of candidate microbicides against early steps of HIV-1 infection upon complement virus opsonization
Authors: Jenabian Mohammad-Ali , Saïdi Héla , Charpentier Charlotte , Bouhlal Hicham , Schols Dominique , Balzarini Jan , Bell Thomas W , Vanham Guido , Bélec Laurent
Published: June 2010

Background

HIV-1 in genital secretions may be opsonized by several molecules including complement components. Opsonized HIV-1 by complement enhances the infection of various mucosal target cells, such as dendritic cells (DC) and epithelial cells.

Results

We herein evaluated the effect of HIV-1 complement opsonization on microbicide candidates' activity, by using three in vitro mucosal models: CCR5-tropic HIV-1JR-CSF transcytosis through epithelial cells, HIV-1JR-CSF attachment on immature monocyte-derived dendritic cells (iMDDC), and infectivity of iMDDC by CCR5-tropic HIV-1BaL and CXCR4-tropic HIV-1NDK. A panel of 10 microbicide candidates [T20, CADA, lectines HHA & GNA, PVAS, human lactoferrin, and monoclonal antibodies IgG1B12, 12G5, 2G12 and 2F5], were investigated using cell-free unopsonized or opsonized HIV-1 by complements. Only HHA and PVAS were able to inhibit HIV trancytosis. Upon opsonization, transcytosis was affected only by HHA, HIV-1 adsorption on iMDDC by four molecules (lactoferrin, IgG1B12, IgG2G5, IgG2G12), and replication in iMDDC of HIV-1BaL by five molecules (lactoferrin, CADA, T20, IgG1B12, IgG2F5) and of HIV-1NDK by two molecules (lactoferrin, IgG12G5).

Conclusion

These observations demonstrate that HIV-1 opsonization by complements may modulate in vitro the efficiency of candidate microbicides to inhibit HIV-1 infection of mucosal target cells, as well as its crossing through mucosa.
The association of 18F-deoxyglucose (FDG) uptake of PET with polymorphisms in the glucose transporter gene (SLC2A1) and hypoxia-related genes (HIF1A, VEGFA, APEX1) in non-small cell lung cancer. SLC2A1 polymorphisms and FDG-PET in NSCLC patients
Authors: Kim Seong-Jang , Hwang Sang-Hyun , Kim In Joo , Lee Min Ki , Lee Chang Hun , Lee Sang-Yull , Lee Eun Yup
Published: June 2010

Background

Positron emission tomography imaging of lung cancers with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose is a non-invasive diagnostic, and prognostic tool that measures tumor metabolism. We have analyzed the effect of solute carrier family 2 (facilitated glucose transporter), member 1 polymorphisms on 2-[fluorine-18]-fluoro-2-deoxy-D-glucose-uptake with a combination of polymorphisms of hypoxia-inducible factor 1 alpha, apurinic/apyimidinic endonuclease, and vascular endothelial growth factor A in a hypoxia-related pathway.

Methods

We investigated the association between solute carrier family 2 (facilitated glucose transporter), member 1 -2841A>T, hypoxia-inducible factor 1 alpha Pro582Ser, Ala588Thr, apurinic/apyimidinic endonuclease Asp148Glu, or vascular endothelial growth factor A +936C>T and 2-[fluorine-18]-fluoro-2-deoxy-D-glucose-uptake among 154 patients with non-small-cell lung cancer.

Results

The solute carrier family 2 (facilitated glucose transporter), member 1 -2841A>T polymorphism was significantly associated with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose-uptake in combination with the apurinic/apyimidinic endonuclease Asp148Glu (T>G) polymorphism in the squamous cell type of non-small-cell lung cancer. The solute carrier family 2 (facilitated glucose transporter), member 1 TT genotype had a higher maximum standardized uptake values than the AA + AT genotype when the apurinic/apyimidinic endonuclease genotype was TT (mean maximum standardized uptake values, 12.47 ± 1.33 versus 8.46 ± 2.90, respectively; P = 0.028). The mean maximum standardized uptake values were not statistically different with respect to vascular endothelial growth factor A and hypoxia-inducible factor 1 alpha polymorphisms.

Conclusion

A glucose transporter gene polymorphism was shown to be statistically associated with glucose-uptake when the apurinic/apyimidinic endonuclease genotype is TT in patients with the squamous cell type of non-small-cell lung cancer. Our findings suggest that a newly developed tracer for positron emission tomography could be affected by genetic polymorphisms.
Hypervolemia induces and potentiates lung damage after recruitment maneuver in a model of sepsis-induced acute lung injury
Authors: Silva Pedro L , Cruz Fernanda F , Fujisaki Livia C , Oliveira Gisele P , Samary Cynthia S , Ornellas Debora S , Maron-Gutierrez Tatiana , Rocha Nazareth N , Goldenberg Regina , Garcia Cristiane SNB , Morales Marcelo M , Capelozzi Vera L , Gama de Abreu Marcelo , Pelosi Paolo , Rocco Patricia RM
Published: June 2010

Introduction

Recruitment maneuvers (RMs) seem to be more effective in extrapulmonary acute lung injury (ALI), caused mainly by sepsis, than in pulmonary ALI. Nevertheless, the maintenance of adequate volemic status is particularly challenging in sepsis. Since the interaction between volemic status and RMs is not well established, we investigated the effects of RMs on lung and distal organs in the presence of hypovolemia, normovolemia, and hypervolemia in a model of extrapulmonary lung injury induced by sepsis.

Methods

ALI was induced by cecal ligation and puncture surgery in 66 Wistar rats. After 48 h, animals were anesthetized, mechanically ventilated and randomly assigned to 3 volemic status (n = 22/group): 1) hypovolemia induced by blood drainage at mean arterial pressure (MAP)≈70 mmHg; 2) normovolemia (MAP≈100 mmHg), and 3) hypervolemia with colloid administration to achieve a MAP≈130 mmHg. In each group, animals were further randomized to be recruited (CPAP = 40 cm H2O for 40 s) or not (NR) (n = 11/group), followed by 1 h of protective mechanical ventilation. Echocardiography, arterial blood gases, static lung elastance (Est,L), histology (light and electron microscopy), lung wet-to-dry (W/D) ratio, interleukin (IL)-6, IL-1β, caspase-3, type III procollagen (PCIII), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) mRNA expressions in lung tissue, as well as lung and distal organ epithelial cell apoptosis were analyzed.

Results

We observed that: 1) hypervolemia increased lung W/D ratio with impairment of oxygenation and Est,L, and was associated with alveolar and endothelial cell damage and increased IL-6, VCAM-1, and ICAM-1 mRNA expressions; and 2) RM reduced alveolar collapse independent of volemic status. In hypervolemic animals, RM improved oxygenation above the levels observed with the use of positive-end expiratory pressure (PEEP), but increased lung injury and led to higher inflammatory and fibrogenetic responses.

Conclusions

Volemic status should be taken into account during RMs, since in this sepsis-induced ALI model hypervolemia promoted and potentiated lung injury compared to hypo- and normovolemia.
Homing of stem cells to sites of inflammatory brain injury after intracerebral and intravenous administration: a longitudinal imaging study
Authors: Jackson Johanna S , Golding Jon P , Chapon Catherine , Jones William A , Bhakoo Kishore K
Published: June 2010

Introduction

This study aimed to determine the homing potential and fate of epidermal neural crest stem cells (eNCSCs) derived from hair follicles, and bone marrow-derived stem cells (BMSCs) of mesenchymal origin, in a lipopolysaccharide (LPS)-induced inflammatory lesion model in the rat brain. Both eNCSCs and BMSCs are easily accessible from adult tissues by using minimally invasive procedures and can differentiate into a variety of neuroglial lineages. Thus, these cells have the potential to be used in autologous cell-replacement therapies, minimizing immune rejection, and engineered to secrete a variety of molecules.

Methods

Both eNCSCs and BMSCs were prelabeled with iron-oxide nanoparticles (IO-TAT-FITC) and implanted either onto the corpus callosum in healthy or LPS-lesioned animals or intravenously into lesioned animals. Both cell types were tracked longitudinally in vivo by using magnetic resonance imaging (MRI) for up to 30 days and confirmed by postmortem immunohistochemistry.

Results

Transplanted cells in nonlesioned animals remained localized along the corpus callosum. Cells implanted distally from an LPS lesion (either intracerebrally or intravenously) migrated only toward the lesion, as seen by the localized MRI signal void. Fluorescence microscopy of the FITC tag on the nanoparticles confirmed the in vivo MRI data,

Conclusions

This study demonstrated that both cell types can be tracked in vivo by using noninvasive MRI and have pathotropic properties toward an inflammatory lesion in the brain. As these cells differentiate into the glial phenotype and are derived from adult tissues, they offer a viable alternative autologous stem cell source and gene-targeting potential for neurodegenerative and demyelinating pathologies.
An analytical solution for natural convective gas microflow in a tall vertical enclosure
Authors: Panda H S , Moulic S Ghosh
Published: June 2010

An analytical solution for buoyancy-induced gas microflow in a tall differentially heated enclosure with isothermal vertical walls is presented. The Navier—Stokes system has been solved. The Boussinesq approximation has been employed. Wall—fluid interactions are modelled by first-order velocity slip and temperature jump conditions. The analysis presented covers continuum to slip-flow regime. A functional form for the Nusselt number has been derived analytically. The results indicate that as the Knudsen number increases, the Nusselt number decreases.
Guided wave-based detection of delamination and matrix cracking in composite laminates
Authors: Wandowski T , Malinowski P , Kudela P , Ostachowicz W
Published: June 2010

The aim of this article was a numerical and experimental study of the active damage detection methods based on piezoelectric elements attached to a composite laminate. In considered case, guided waves were excited and received in a structure using pulse-echo method. It means that after exciting a structure with a pulse, an array of sensors located on a structure was used to ‘listen' for reflected waves coming from discontinuities. The main part of structural health monitoring system is signal-processing algorithms, which allow to detect and localize damage. Algorithm applied in this research results in special maps that indicate damage location. In this article, a damage localization algorithm was described and experimentally tested. The proposed method was successfully tested on a carbon—epoxy part of a helicopter.
Viscoelastic modelling of rotor—shaft systems using an operator-based approach
Authors: Dutt J K , Roy H
Published: June 2010

Damping exists in every material in varying degrees, so materials in general are viscoelastic in nature. Energy storage, as well as dissipation in varying degrees, accompanies every time-varying deformation, with the effect that stress and strain in a material get out of phase. This work presents the development of equations of motion of a rotor—shaft system with a viscoelastic rotor after discretizing the system into finite elements. Subsequently, these equations are used to study the dynamics of the rotor—shaft system in terms of stability limit of spin speed and time response of a disc as a result of unbalance. The primary inspiration for a viscoelastic model arises from the need to capture the influence of broad band spectral behaviour of rotor—shaft materials, primarily polymers and polymer composites, which are principally the materials of light rotors, on the dynamics of rotor—shaft system. For this, the material constitutive relationship has been represented by a differential time operator. Use of operators enables one to consider general linear viscoelastic behaviours, represented in the time domain by multi-element (three, four, or higher elements) spring—dashpot models or internal variable models, for which, in general, instantaneous stress and its derivatives are proportional to instantaneous strain and its derivatives. Again such representation is fairly generic, in a sense that the operator may be suitably chosen according to the material model to obtain the equations of motion of a rotor—shaft system. The equations so developed may be easily used to find the stability limit speed of a rotor—shaft system as well as the time response when the rotor—shaft system is subjected to any dynamic forcing function.
An investigation on the effect of diamond concentration and matrix material composition in the circular sawing process of granites
Authors: Ucun İ , Aslantas K , Büyüksagis İ S , Tasgetiren S
Published: June 2010

In the process of natural stone cutting, segmented circular diamond saw blades are widely used in the sawing process of granites. Generally, copper, cobalt, or a combination of these is used as the matrix material. The diamond particle used in segments is added to the matrix material in certain rates and sizes. In this article, the effect of tungsten, cobalt, copper, and tin elements, which are added to the matrix material, on the cutting performance was studied. In addition, in order to study the effect of diamond concentration, the segments with different diamond concentration were manufactured. Using these segments, cutting experiments for granite, which are known as natural hard stones, are conducted. In the cutting experiments, peripheral speed of the cutting disc, cutting speed, and depth cut were taken as constant. After the experiments, cutting forces, power consumption, and specific energy changes for each segment were determined. On the other hand, the status of damage and wear for the surfaces of each segment during the cutting process was evaluated in terms of segment performances. According to the results, an increase in diamond concentration results in a lower cutting force and power consumption and also causes a lower specific wear of the segment.
Design optimization of composite structures for maximum strength using direct simulated annealing
Authors: Ertas A H , Sonmez F O
Published: June 2010

Composite materials have been used in many structural applications because of their superior properties. Although composites are less sensitive to deformation, their increased use has emphasized that their deformation behaviours and hence deformation analyses are more complex than for structures of uniform composition. Deformation patterns contingent upon fatigue properties of composites may vary significantly because of the large differences in properties of the fibres and matrix, and the compositions of their sub-constituents. These complexities introduce major deficiencies to methods for composite materials, which often force large factors of safety to be adopted in designs. Consequently, composite structures used in fatigue applications are generally over-designed to eliminate catastrophic failure and are therefore heavier and more costly.

Accordingly, the objective of this study is to develop a methodology to maximize the load-carrying capacity or strength of composite structures by minimizing the maximum stress. A stochastic global search algorithm called the direct search simulated annealing is employed in the optimization procedure. The methodology is applied to different types of problems to demonstrate the effectiveness and reliability of the proposed method.
Mechanical behaviour of functionally graded plates under static and dynamic loading
Authors: Akbarzadeh A H , Zad S K Hosseini , Eslami M R , Sadighi M
Published: June 2010

This article presents an analytical solution for the mechanical behaviour of rectangular plates made of functionally graded materials (FGMs) based on the first-order shear deformation theory (FSDT) and the third-order shear deformation theory (TSDT). The FGM plate is assumed to be graded across the thickness. The material properties of the FGM plate are assumed to vary continuously through the thickness of the plate according to a power law distribution of the volume fraction of the constituent materials, except Poisson's ratio, which is assumed to be constant. The plate is subjected to a lateral mechanical load on its upper surface. The equations of motion are written based on displacement fields. The partial differential equations have been solved by the Fourier series expansion. Using the Laplace transform, unknown variables are obtained in the Laplace domain. The resulting formulations enable one to perform the static, dynamic, and free vibration analysis for both FSDT and TSDT plates. Employing the analytical Laplace inversion method and numerical time integration technique based on the Newmark method, time function solution of the problem is obtained and the unknown parameters are derived for a dynamic loading situation. Finally, the natural frequencies of the plate are obtained and dynamic responses are presented in the form of combinations of different frequencies. The results are verified with those reported in the literature.
A fresh insight into the non-linear vibration of double-tapered atomic force microscope cantilevers by considering the Hertzian contact theory
Authors: Sadeghi A , Zohoor H
Published: June 2010

The non-linear flexural vibration for a double-tapered atomic force microscope cantilever has been investigated by using the Timoshenko beam theory. In this article, the normal and tangential tip—sample interaction forces are found from the Hertzian contact model, and the effects of the contact position, normal and lateral contact stiffness, height of the tip, thickness of the beam, angle between the cantilever and the sample surface, and breadth and height taper ratios on the non-linear frequency to linear frequency ratio have been studied. The differential quadrature method is employed to solve the non-linear differential equations of motion. The results show that the softening behaviour is seen for all cases. The non-linear frequency to linear frequency ratio increases by increasing the Timoshenko beam parameter and breadth and height taper ratios, but decreases by increasing the contact position for the first and second modes. For the first vibrational mode, the non-linear frequency to linear frequency ratio increases by increasing the height of the tip and the angle α between the cantilever and sample surface. By increasing the normal contact stiffness, the frequency ratio increases for the first mode.
The influence of tool geometry on the thermo-mechanical and microstructural behaviour in friction stir welding of AA5086
Authors: Aval H Jamshidi , Serajzadeh S , Kokabi A H
Published: June 2010

In this work, the effect of tool geometric parameters on thermo-mechanical behaviour in friction stir welding of AA5086 has been investigated. For doing so, the thermo-mechanical responses of material during welding with different tools have been predicted by a three-dimensional finite-element model using the finite-element code ABAQUS. In addition, welding experiments have been carried out to study the developed microstructures and the mechanical properties of welded alloy. The results show that tool geometry significantly affects the energy input, deformation pattern, plunge force, microstructures, and mechanical properties of the joint. The conical tool with the shoulder angle of 2° has been found to produce a larger deformation region as well as higher mechanical properties comparing with the cylindrical tools employed in this research. Additionally, tensile residual stresses are developed within the region around the weld centre-line, which gradually changes to compressive ones beyond the heat-affected zone. It is found that the ratio of heat generation from plastic to friction dissipation in the conical threaded pin is 44 per cent more than the cylindrical pin with similar shoulder diameter.
Experimental Characterization and Modelling of a Side Buffer for Freight Trains
Authors: Cheli F , Melzi S
Published: June 2010

A detailed investigation performed by European Rail Research Institute (ERRI) relevant to the safe running of heavy freight trains revealed how levels of buffer forces exceeding 240 kN can deeply reduce the safety margins of a train-set. Even if the analysis pointed out the role played by buffers in affecting running safety, little is known about their response; according to the UIC 526-1, buffers mounted on freight trains should satisfy general requirements in terms of stored and dissipated energy under quasi-static load cycles and during impacts between adjacent vehicles at given relative speeds. This work aims at characterizing the buffer response under working conditions close to the ones experienced during critical manoeuvres like braking while cornering or when passing over switches. A special test bench was thus set up to impose static and dynamics loads on a buffer through hydraulic actuators, considering also misaligned axial forces and the application of tangential forces reproducing the effect of friction between adjacent buffers; data collected through experimentation were then used to develop a complex rheological model of the component. The model of buffer was eventually introduced into a simulation code to investigate the effect of its response on the train-set dynamics.
Railway Bridge Approaches under Heavy Axle Load Traffic: Problems, Causes, and Remedies
Authors: Li D , Otter D , Carr G
Published: June 2010

This article presents findings from projects conducted by the Transportation Technology Center, Inc. concerning track maintenance problems associated with bridge approaches of railway track. Field tests for determining root causes of, and evaluating remedies for, such problems were conducted at the Facility for Accelerated Service Testing near Pueblo, Colorado, and at a number of revenue service sites in the United States. Investigations covered ballast deck concrete bridges with concrete ties, open deck steel bridges with wood ties, and their approaches.
Aerodynamic Crosswind Stability of a Regional Train Model
Authors: Diedrichs B
Published: June 2010

This work compares aerodynamic results of crosswind stability obtained experimentally and numerically for a typical regional train model. The experimental work focuses attention on relatively high yaw angles of 30°, 41.5°, 50°, and 60°, whereas the numerical results are confined to 30° and 41.5° that are typically critical for regional trains. In particular, two vehicle models (VM1 and VM2) with different roof configurations are exploited numerically. VM1 has a flat roof with two boxy roof equipments. VM2 has a flat roof where the roof equipments are streamlined.

The numerical work addresses the ability to resolve the flow field around the vehicles subjected to relatively high yaw angles with Reynolds average navier-stokes (RANS) and Delayed-Detached Eddy Simulation (D-DES) by employing the commercial code STAR-CD in conjunction with automatically generated polyhedral meshes of CCM+. High- and low-Reynolds meshes are exploited for this purpose. The massively separated flow, for the higher yaw angles, on the leeward side of the vehicles justifies the use of D-DES, where the results show good agreement with the experi-mental work. The results of RANS are fair, and the ability to predict the challenging lift force is again found to be problematic.
Wheel Tread Damage: A Numerical Study of Railway Wheel Tread Plasticity under Thermomechanical Loading
Authors: Vernersson T , Caprioli S , Kabo E , Hansson H , Ekberg A
Published: June 2010

A numerical study is presented where the impact of simultaneous thermal and mechanical loading on a railway wheel tread, as imposed by braking and rolling contact, is reported. A comparison is made of two-dimensional (2D) and 3D finite-element simulations of the thermomechanical problem featuring a material model that accounts for thermal expansion and plastic deformations. It is found that 2D simulations give unrealistic predictions of plastic deformations. The 3D simulations demonstrate a significant influence of the thermal loading also in cases of rather moderate temperature increases. In particular, the combination of thermal loading and high traction is found to be very detrimental.
Brake Rig Influence on Vehicle Dynamics
Authors: Kovtun H , Markova O , Litvin V , Kik W , Scheffel H
Published: June 2010

A mathematical model of conventional freight car motion with constant speed is developed taking the work of brake equipment into account. The influence of freight car conventional brake rig on the vehicle dynamics at motion is studied. The results obtained at the computer simulation have shown that in some cases brake equipment can worsen the car dynamics.
Workspace Analysis and Design Improvement of a Carotid Flow Measurement System
Authors: Carbone G , Nakadate R , Solis J , Ceccarelli M , Takanishi A , Minagawa E , Sugawara M , Niki K
Published: June 2010

Heart and cerebrovascular diseases such as arteriosclerosis and myocardial ischemia dysfunction are currently among the main causes of death in developed countries. Recently, wave intensity (WI), which is an index used to obtain the force of cardiac contraction, has been investigated as a method for early-stage diagnosis of the above-mentioned diseases. Nevertheless, experimental tests have proven that the manual measurements of WI by means of commercial ultrasonic diagnostic systems require too much time and can be affected by the operator's skills. For this purpose, the introduction of robotic-assisted technology has advantages in terms of repetitiveness and accuracy of the measurement procedure. Therefore, at Waseda University, the development of a carotid blood flow measurement system has been proposed to support doctors while using ultrasound diagnostic equipment to measure the WI. This robotic system is composed of a serial robot with a wrist having a six-degree-of-freedom (6-DOF) parallel mechanism. The main focus is to obtain a suitable workspace performance of the 6-DOF parallel mechanism wrist. In this paper, a workspace analysis is carried out on a wrist prototype built for the Waseda-Tokyo Women's Medical Aloka Blood Flow Measurement System No.1 Refined (WTA-1R). Then, mechanical design enhancements are proposed and validated to provide a suitable workspace performance both as reachable workspace and dexterity, and a refined prototype WTA-1RII has been built.
Characterizing Bubble Dynamics Created by High-Intensity Focused Ultrasound for the Delivery of Antibacterial Nanoparticles into a Dental Hard Tissue
Authors: Ohl S-W , Shrestha A , Khoo B C , Kishen A
Published: June 2010

Hig hintensity focused ultrasound (HIFU) has been applied for drug delivery in various disease conditions. Delivery of antibacterial-nanoparticles into dental hard tissues may open up new avenues in the treatment of dental infections. However, the basic mechanism of bubble dynamics, its characterization, and working parameters for effective delivery of nanoparticles, warrants further understanding. This study was conducted to highlight the basic concept of HIFU and the associated bubble dynamics for the delivery of nanoparticles. Characterization experiments to deliver micro-scale particles into simulated tubular channels, activity of ultrasonic bubbles, and pressure measurement inside the HIFU system were conducted. Subsequently, experiments were carried out to test the ability of HIFU to deliver nanoparticles into human dentine using field emission scanning electron micrographs (FESEM) and elemental dispersive X-ray analysis (EDX). The characterization experiments showed that the bubbles collapsing at the opening of tubular channels were able to propel particles along their whole length. The pressure measured showed sufficient negative and positive pressure suggesting that the bubble grew to a certain size before collapsing, thus enabling the particles to be pushed. The FESEM and EDX analysis highlighted the ability of HIFU to deliver nanoparticles deep within the dentinal tubules. This study highlighted the characteristics and the mechanism involved of the bubbles generated by the HIFU and their capability to deliver nanoparticles.
Challenges Facing Quantification of Rat Locomotion along Beams of Varying Widths
Authors: Madete J K , Klein A , Fuller A , Trueman R C , Rosser A E , Dunnett S B , Holt C A
Published: June 2010

Optoelectronic motion capture systems have been widely used to investigate temporal gait parameters in humans and animals in order to understand function and behavioural attributes of different pathologies, e.g. Parkinson's disease (PD). The aim of the present paper was to investigate the practicality of utilising this system to investigate the effects of a unilateral 6-hydroxydopamine (6-OHDA) lesion on rat locomotion while walking on beams of varying widths (graduated, narrow, and wide). Temporal gait parameters of ten male Lister Hooded rats (five controls and five hemiparkinsonian) were observed using passive markers placed in locations that were representative of their four limbs and their body axis. The results demonstrate that marker-based motion capture can provide an effective and simple approach to quantifying temporal gait parameters for rat models of PD. They also reveal how the width of the path affects the locomotion in both experimental cohorts. Such measurements can be compared with human motion analysis to explore correlations between the animal model and human behaviour, which is an important step for translational medicine.
An Interspecies Computational Study on Limb Lengthening
Authors: Reina-Romo E , Gómez-Benito M J , García-Aznar J M , Domínguez J , Doblaré M
Published: June 2010

Distraction osteogenesis is a surgical technique that produces large volumes of new bone by gradually separating two osteotomized bone segments. A previously proposed mechanical-based model that includes the effect of pre-traction stresses (stress level in the gap tissue before each distraction step) during limb lengthening is used here. In the present work, the spatial and temporal patterns of tissue distribution during distraction osteogenesis in different species (sheep, rabbit) and in the human are compared numerically to predict experimental results. Interspecies differential characteristics such as size, distraction protocol, and rate of distraction, among others, are chosen according to experiments. Tissue distributions and reaction forces are then analysed as indicators of the healing pattern. The results obtained are in agreement with experimental findings regarding both tissue distribution and reaction forces. The ability of the model to qualitatively predict the two animal models and the human healing pattern in distraction osteogenesis indicates its potential in understanding the influence of mechanics in this complex process.
The effects of alkali treatment on the interfacial adhesion of bamboo fibres
Authors: Wong K J , Yousif B F , Low K O
Published: June 2010

In the present work, the potential of using bamboo fibres as reinforcement for polyester composites was evaluated. Two types of bamboo fibres were used: untreated and treated with different NaOH concentrations (1, 3, and 5wt%). Mechanical properties of both treated and untreated fibres were investigated. In addition, single-fibre pull-out tests were performed to study the interfacial shear strength of the fibres with the polyester matrix at different embedment length of fibres. Scanning electron microscopy was used to study the surface morphology of the fibres before and after the tests. Results revealed that an untreated fibre has the best strength and stiffness but lowest strain at break. An increase in alkali concentration reduces the strain at failure and ductility of bamboo fibres. However, the strength and stiffness of the fibres were increased. In addition, the interfacial shear strength was improved with longer embedment length and higher NaOH concentration.
A kinematic analysis of meshing polymer gear teeth
Authors: Karimpour M , Dearn K D , Walton D
Published: June 2010

This article describes an investigation into the contact behaviour of polymeric gear transmissions using numerical finite element (FE) and analytical techniques. A polymer gear pair was modelled and analysed using the ABAQUS software suite and the analytical results were calculated using the BS ISO 6336 rating standard. Before describing the results, the principles of the strategies and methods employed in the building of the FE model have been discussed. The FE model dynamically simulated a range of operating conditions. The simulations showed that the kinematic behaviour of polymeric gears is substantially different from those predicted by the classical metal gear theory. Extensions to the path of contact occur at the beginning and end of the meshing cycle. These are caused by large tooth deflections experienced by polymer gear teeth, as a result of much lower values of stiffness compared to metallic gears. The premature contact (occurring at the beginning of the meshing cycle) is hypothesized to be a factor in pitch line tooth fractures, whereas the extended contact is thought to be a factor in the extreme wear as seen in experiments. Furthermore, the increase in the path of contact also affects the induced bending and contact stresses. Simulated values are compared against those predicted by the international gear standard BS ISO 6336 and are shown to be substantially different. This is particularly for the case for bending stresses, where analytically derived values are independent of contact stiffness. The extreme tooth bending and the differences between analytical and numerical stresses observed in all the simulations suggest that any future polymeric gear-rating standard must account for the effects of load sharing (as a result of tooth deflection) and friction (particularly in dry-running applications).