bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of Ce/Al2O3 composite coating on anodised aluminium film by ac deposition method
Authors: Liang C. H. , Liang K. , Huang N. B.
Published: March 2009

In order to prepare Ce/Al2O3 composite coating on oxide film quickly, a new process of ac deposition method in a solution containing H2O2 and CeCl3 was introduced. Scanning electron microscopy/energy dispersive X-ray spectroscopy, electron probe microanalyser, X-ray diffractometer and X-ray photoelectron spectroscopy were adopted to analyse the coating. The results showed that the Ce/Al2O3 composite coating was easy to prepare when the Al2O3 film thickness was over 6·8 μm. The Ce sediment was amorphous of cerium (III and IV) hydroxide and located into the pores near the surface of Al2O3 films layer. The forming mechanism of the composite coating was discussed accordingly.
How we treat cytomegalovirus in hematopoietic cell transplant recipients
Authors: Boeckh Michael , Ljungman Per
Published: March 2009

Cytomegalovirus (CMV) continues to cause major complications after hematopoietic cell transplantation (HCT). Over the past decade, most centers have adopted preemptive antiviral treatment or prophylaxis strategies to prevent CMV disease. Both strategies are effective but also have shortcomings with presently available drugs. Here, we review aspects of CMV treatment and prevention in HCT recipients, including currently used drugs and diagnostics, ways to optimize preemptive therapy strategies with quantitative polymerase chain reaction assays, the use of prophylaxis, management of CMV disease caused by wild-type or drug-resistant strains, and future strategies.
Generation of induced pluripotent stem cells from human blood
Authors: Loh Yuin-Han , Agarwal Suneet , Park In-Hyun , Urbach Achia , Huo Hongguang , Heffner Garrett C. , Kim Kitai , Miller Justine D. , Ng Kitwa , Daley George Q.
Published: March 2009

Human dermal fibroblasts obtained by skin biopsy can be reprogrammed directly to pluripotency by the ectopic expression of defined transcription factors. Here, we describe the derivation of induced pluripotent stem cells from CD34+ mobilized human peripheral blood cells using retroviral transduction of OCT4/SOX2/KLF4/MYC. Blood-derived human induced pluripotent stem cells are indistinguishable from human embryonic stem cells with respect to morphology, expression of surface antigens, and pluripotency-associated transcription factors, DNA methylation status at pluripotent cell-specific genes, and the capacity to differentiate in vitro and in teratomas. The ability to reprogram cells from human blood will allow the generation of patient-specific stem cells for diseases in which the disease-causing somatic mutations are restricted to cells of the hematopoietic lineage.
Digital PCR provides sensitive and absolute calibration for high throughput sequencing
Authors: White Richard A , Blainey Paul C , Fan H Christina , Quake Stephen R
Published: March 2009

Background

Next-generation DNA sequencing on the 454, Solexa, and SOLiD platforms requires absolute calibration of the number of molecules to be sequenced. This requirement has two unfavorable consequences. First, large amounts of sample-typically micrograms-are needed for library preparation, thereby limiting the scope of samples which can be sequenced. For many applications, including metagenomics and the sequencing of ancient, forensic, and clinical samples, the quantity of input DNA can be critically limiting. Second, each library requires a titration sequencing run, thereby increasing the cost and lowering the throughput of sequencing.

Results

We demonstrate the use of digital PCR to accurately quantify 454 and Solexa sequencing libraries, enabling the preparation of sequencing libraries from nanogram quantities of input material while eliminating costly and time-consuming titration runs of the sequencer. We successfully sequenced low-nanogram scale bacterial and mammalian DNA samples on the 454 FLX and Solexa DNA sequencing platforms. This study is the first to definitively demonstrate the successful sequencing of picogram quantities of input DNA on the 454 platform, reducing the sample requirement more than 1000-fold without pre-amplification and the associated bias and reduction in library depth.

Conclusion

The digital PCR assay allows absolute quantification of sequencing libraries, eliminates uncertainties associated with the construction and application of standard curves to PCR-based quantification, and with a coefficient of variation close to 10%, is sufficiently precise to enable direct sequencing without titration runs.
The prevalence of BRCA1 mutations among young women with triple-negative breast cancer
Authors: Young SR , Pilarski Robert T , Donenberg Talia , Shapiro Charles , Hammond Lyn S , Miller Judith , Brooks Karen A , Cohen Stephanie , Tenenholz Beverly , DeSai Damini , Zandvakili Inuk , Royer Robert , Li Song , Narod Steven A
Published: March 2009

Background

Molecular screening for BRCA1 and BRCA2 mutations is now an established component of risk evaluation and management of familial breast cancer. Features of hereditary breast cancer include an early age-of-onset and over-representation of the 'triple-negative' phenotype (negative for estrogen-receptor, progesterone-receptor and HER2). The decision to offer genetic testing to a breast cancer patient is usually based on her family history, but in the absence of a family history of cancer, some women may qualify for testing based on the age-of-onset and/or the pathologic features of the breast cancer.

Methods

We studied 54 women who were diagnosed with high-grade, triple-negative invasive breast cancer at or before age 40. These women were selected for study because they had little or no family history of breast or ovarian cancer and they did not qualify for genetic testing using conventional family history criteria. BRCA1 screening was performed using a combination of fluorescent multiplexed-PCR analysis, BRCA1 exon-13 6 kb duplication screening, the protein truncation test (PTT) and fluorescent multiplexed denaturing gradient gel electrophoresis (DGGE). All coding exons of BRCA1 were screened. The two large exons of BRCA2 were also screened using PTT. All mutations were confirmed with direct sequencing.

Results

Five deleterious BRCA1 mutations and one deleterious BRCA2 mutation were identified in the 54 patients with early-onset, triple-negative breast cancer (11%).

Conclusion

Women with early-onset triple-negative breast cancer are candidates for genetic testing for BRCA1, even in the absence of a family history of breast or ovarian cancer.
Adenoviral vectors for highly selective gene expression in central serotonergic neurons reveal quantal characteristics of serotonin release in the rat brain
Authors: Benzekhroufa Kheira , Liu Beihui , Tang Feige , Teschemacher Anja G , Kasparov Sergey
Published: March 2009

Background

5-hydroxytryptamine (5 HT, serotonin) is one of the key neuromodulators in mammalian brain, but many fundamental properties of serotonergic neurones and 5 HT release remain unknown. The objective of this study was to generate an adenoviral vector system for selective targeting of serotonergic neurones and apply it to study quantal characteristics of 5 HT release in the rat brain.

Results

We have generated adenoviral vectors which incorporate a 3.6 kb fragment of the rat tryptophan hydroxylase-2 (TPH-2) gene which selectively (97% co-localisation with TPH-2) target raphe serotonergic neurones. In order to enhance the level of expression a two-step transcriptional amplification strategy was employed. This allowed direct visualization of serotonergic neurones by EGFP fluorescence. Using these vectors we have performed initial characterization of EGFP-expressing serotonergic neurones in rat organotypic brain slice cultures. Fluorescent serotonergic neurones were identified and studied using patch clamp and confocal Ca2+imaging and had features consistent with those previously reported using post-hoc identification approaches. Fine processes of serotonergic neurones could also be visualized in un-fixed tissue and morphometric analysis suggested two putative types of axonal varicosities. We used micro-amperometry to analyse the quantal characteristics of 5 HT release and found that central 5 HT exocytosis occurs predominantly in quanta of ~28000 molecules from varicosities and ~34000 molecules from cell bodies. In addition, in somata, we observed a minority of large release events discharging on average ~800000 molecules.

Conclusion

For the first time quantal release of 5 HT from somato-dendritic compartments and axonal varicosities in mammalian brain has been demonstrated directly and characterised. Release from somato-dendritic and axonal compartments might have different physiological functions. Novel vectors generated in this study open a host of new experimental opportunities and will greatly facilitate further studies of the central serotonergic system.
Suppression of HIV-1 replication by microRNA effectors
Authors: Chable-Bessia Christine , Meziane Oussama , Latreille Daniel , Triboulet Robinson , Zamborlini Alessia , Wagschal Alexandre , Jacquet Jean-Marc , Reynes Jacques , Levy Yves , Saib Ali , Bennasser Yamina , Benkirane Monsef
Published: March 2009

The rate of HIV-1 gene expression is a key step that determines the kinetics of virus spread and AIDS progression. Viral entry and gene expression were described to be the key determinants for cell permissiveness to HIV. Recent reports highlighted the involvement of miRNA in regulating HIV-1 replication post-transcriptionally. In this study we explored the role of cellular factors required for miRNA-mediated mRNA translational inhibition in regulating HIV-1 gene expression. Here we show that HIV-1 mRNAs associate and co-localize with components of the RNA Induced Silencing Complex (RISC), and we characterize some of the proteins required for miRNA-mediated silencing (miRNA effectors). RCK/p54, GW182, LSm-1 and XRN1 negatively regulate HIV-1 gene expression by preventing viral mRNA association with polysomes. Interestingly, knockdown of RCK/p54 or DGCR8 resulted in virus reactivation in PBMCs isolated from HIV infected patients treated with suppressive HAART.
A randomized, double-blind, placebo-controlled pilot study of a probiotic in emotional symptoms of chronic fatigue syndrome
Authors: Rao A Venket , Bested Alison C , Beaulne Tracey M , Katzman Martin A , Iorio Christina , Berardi John M , Logan Alan C
Published: March 2009

Chronic fatigue syndrome (CFS) is complex illness of unknown etiology. Among the broad range of symptoms, many patients report disturbances in the emotional realm, the most frequent of which is anxiety. Research shows that patients with CFS and other so-called functional somatic disorders have alterations in the intestinal microbial flora. Emerging studies have suggested that pathogenic and non-pathogenic gut bacteria might influence mood-related symptoms and even behavior in animals and humans. In this pilot study, 39 CFS patients were randomized to receive either 24 billion colony forming units of Lactobacillus casei strain Shirota (LcS) or a placebo daily for two months. Patients provided stool samples and completed the Beck Depression and Beck Anxiety Inventories before and after the intervention. We found a significant rise in both Lactobacillus and Bifidobacteria in those taking the LcS, and there was also a significant decrease in anxiety symptoms among those taking the probiotic vs controls (p = 0.01). These results lend further support to the presence of a gut-brain interface, one that may be mediated by microbes that reside or pass through the intestinal tract.
RacGAP50C directs perinuclear γ-tubulin localization to organize the uniform microtubule array required forDrosophilamyotube extension
Authors: Guerin Colleen M. , Kramer Sunita G.
Published: March 2009

The microtubule (MT) cytoskeleton is reorganized during myogenesis as individual myoblasts fuse into multinucleated myotubes. Although this reorganization has long been observed in cell culture, these findings have not been validated during development, and proteins that regulate this process are largely unknown. We have identified a novel postmitotic function for the cytokinesis proteins RacGAP50C (Tumbleweed) and Pavarotti as essential regulators of MT organization during Drosophila myogenesis. We show that the localization of the MT nucleator γ-tubulin changes from diffuse cytoplasmic staining in mononucleated myoblasts to discrete cytoplasmic puncta at the nuclear periphery in multinucleated myoblasts, and that this change in localization depends on RacGAP50C. RacGAP50C and γ-tubulin colocalize at perinuclear sites in myotubes, and in RacGAP50C mutantsγ-tubulin remains dispersed throughout the cytoplasm. Furthermore, we show that the mislocalization of RacGAP50C in pavarotti mutants is sufficient to redistribute γ-tubulin to the muscle fiber ends. Finally,myotubes in RacGAP50C mutants have MTs with non-uniform polarity,resulting in multiple guidance errors. Taken together, these findings provide strong evidence that the reorganization of the MT network that has been observed in vitro plays an important role in myotube extension and muscle patterning in vivo, and also identify two molecules crucial for this process.
Ultrasound estimation of breast tissue biomechanical properties using a similarity-based non-linear optimization approach
Authors: Li J , Cui Y , English R E , Alison Noble J
Published: March 2009

The in vivo estimation of tissue elasticity parameters is important for realistic tissue deformation modelling and diagnosis tasks such as cancer mass detection and characterization. Elastography (strain imaging) provides non-quantitative information about tissue stiffness and is becoming well established clinically. Acoustic radiation force imaging, supersonic shear wave imaging and (Young's) modulus imaging are all evolving as quantitative methods. This paper concerns the latter. The established approach to Young's modulus reconstruction involves solving the so-called inverse elasticity problem of recovering elastic parameters by comparing the displacement field from the measurements and the theoretical tissue deformation modelling. In this paper, a new modulus imaging pathway is proposed in which the inverse problem of elasticity reconstruction has been converted into a global optimization problem involving an image similarity measure. This approach is applied to ultrasound images and the tissue elasticity distribution is recovered by adaptively adding new regions based on the local mismatch of the images using a multiscaled split-and-merge approach. For this experimental evaluation of the performance of the proposed method, first synthetic images are used with different Gaussian noise levels. The reconstructed elasticity shows good agreement with the ground-truth. A comparison of the proposed method with a conventional displacement-based method is made using a gelatine phantom. The results using both methods agree remarkably well with the theoretical prediction. A further in vivo study on 19 breast cancer masses was performed. The present method estimated an elasticity contrast of 6.41 ± 0.98 between cancerous tissue and normal tissue, which is consistent with values reported elsewhere in the literature.
Measuring strain distributions in the tendon using confocal microscopy and finite elements
Authors: Screen H R C , Evans S L
Published: March 2009

Tendon is a multilevel fibre composite material, which generates complex variable local strains in response to gross loading. The tendon cells are located in long rows between collagen fibres, where they respond to the local strain environment with the initiation of mechanotransduction pathways, to control matrix maintenance and remodelling. Knowledge of the local strain environment is thus an important component in understanding tenocyte mechanotransduction. Confocal microscopy has previously been utilized to visualize the tendon matrix during loading, to investigate local strains. Using the cells as strain markers, their response during quasi-static loading or stress relaxation can be monitored. This study presents a novel method of analysing the resulting images, to provide an overview of the strain environment throughout the tendon sample. The cell markers are used as nodes in a mesh of triangular elements and the mathematical approach adopted in the finite element method is used to find the strain distribution. The analysis highlighted widely variable strains within the matrix during stress relaxation, with strains far greater than those applied to the sample. Large shear strains were indicative of fibre sliding during the relaxation process, while large transverse strains were also recorded throughout the sample, highlighting an overall reduction in sample volume. These data indicate an exudation of water from the samples during stress relaxation and suggest that the tenocytes are subjected to significant compressive strains. This analysis technique has great potential for measuring deformation of small tissue samples and understanding interactions between external loads, the extracellular matrix, and cells. This mathematical approach is likely to have other applications in biomechanics and could give even better results in other tissues with a higher density of cells and a less discontinuous strain distribution.
New die design for improvement of die corner filling in hydroforming of cylindrical stepped tubes
Authors: Elyasi M , Bakhshi-Jooybari M , Gorji A , Hosseinipour S J , Nourouzi S
Published: March 2009

Seamless tubular components, such as stepped tubes, conical tubes, and box shape tubes, are produced mainly in the tube hydroforming process. In forming the components in this process, complete filling of the die corners and obtaining a sharp corner is very difficult or even impossible. In this paper, the die corner filling in hydroforming of cylindrical stepped tubes was improved by a new die set. The proposed die was simulated and the filling of the die cavity was investigated. In order to verify the simulation results, the new die set was manufactured and some experiments were performed. It is shown that by using the new die set the parts with sharp corners and with more uniform thickness distribution could be produced. The simplicity of the die and low internal pressure are further advantages.
Comparisons of neural network models on surface roughness in electrical discharge machining
Authors: Pradhan M K , Das R , Biswas C K
Published: March 2009

In this work, two different artificial neural network (ANN) models — back-propagation neural network (BPN) and radial basis function neural network (RBFN) — are presented for the prediction of surface roughness in die sinking electrical discharge machining (EDM). The pulse current (Ip), the pulse duration (Ton), and duty cycle (τ) are chosen as input variables with a constant voltage of 50 volt, and surface roughness is the output parameters of the model. A widespread series of EDM experiments was conducted on AISI D2 steel to acquire the data for training and testing and it was found that the neural models could predict the process performance with reasonable accuracy, under varying machining conditions. However, RBFN is faster than the BPNs and the BPN is reasonably more accurate. Moreover, they can be considered as valuable tools for EDM, by giving reliable predictions and provide a possible way to avoid time-and money-consuming experiments.
Optimum damage and surface roughness prediction in end milling glass fibre-reinforced plastics, using neural network and genetic algorithm
Authors: Razfar M R , Zadeh M R Zanjani
Published: March 2009

This paper presents an approach for the determination of the optimal cutting parameters (spindle speed, feed rate, and depth of cut) and end mill flutes leading to minimum surface roughness and delamination factor in end milling of glass fibre reinforced plastics (GFRP) by coupling neural network (NN) and genetic algorithm (GA). In this regard, the advantages of statistical experimental design technique, experimental measurements, artificial neural network, and genetic optimization method are exploited in an integrated manner. The genetically optimized neural network system (GONNS) is proposed for the selection of the optimal cutting conditions from the experimental data when an analytical model is not available. GONNS uses back-propagation (BP) type NNs to represent the input and output relations of the considered system. The GA obtains the optimal operational conditions through using the NNs. From this, it can be clearly seen that a good agreement is observed between the predicted values and the experimental measurements.
Experimental investigation of sheet metal formability under various strain rates
Authors: Dariani B M , Liaghat G H , Gerdooei M
Published: March 2009

Formability of sheet metals is often assessed by means of forming limit diagrams (FLD). In this paper, performing three different series of experiments, the effect of forming velocity on FLDs is investigated experimentally for Al 6061-T6 and AISI 1045 sheets. In addition to determining the conventional FLDs at quasi-static condition (

The results show that while a substantial improvement in high strain rate formability of the aluminium sheet can be obtained, this improvement is not considerable for the steel sheets. Also, under the effect of contact pressure between tool and sheet, the formability increases for both steel and aluminium sheets on impact.
The influence of selectable parameters in the element-free Galerkin method: A one-dimensional beam-in-bending problem
Authors: Valencia O F , Gómez-Escalonilla F J , López-Díez J
Published: March 2009

Continuing with the analysis performed for the one-dimensional axially loaded bar problem, a beam in bending is analysed to understand the influence of the characteristic parameters that have any influence in the solution of this problem using the element-free Galerkin method (EFGM), one of the most popular meshless methods. Both accuracy and time cost are considered as the evaluation functions to perform such an analysis. Both functions provide a reasonable idea to consider EFGM as an adequate method to solve the problem considered in this article. As in a one-dimensional axially loaded bar problem, the parameters to be considered will be those that affect the solution: number of nodes in which the domain is modelled, the nodes scatter, the order of the polynomial base to generate shape functions, the order of the quadrature to solve integrals, and the support radius. Besides, as in a one-dimensional axially loaded problem, some cases with different loading and stiffness conditions are considered. However, in this analysis a generalized moving least squares method is used to create shape functions instead of the moving least squares.
Detection of aerodynamic noise sources in low-speed axial fans with tip end-plates
Authors: Bianchi S , Corsini A , Rispoli F , Sheard A G
Published: March 2009

This article reports on the use of modified blade-tip configurations designed with a view to passive noise control in low-speed fans for compact cooling units. The addition of end-plates at the tip of a datum fan blade is shown to have a positive influence on the fan's rotor-only aero-acoustic signature. The aerodynamic effects of the modified blade tips are experimentally tested in a fully ducted configuration in the near field and far field using a correlation technique. The nature of the flow mechanisms in the blade-tip region are correlated with the specific end-plate design features and their role in the creation of overall acoustic emissions is clarified. The noise emitted by the fans is analysed in terms of coherent vortex structures, tip-leakage flow, and noise sources. Differences in human perception of the noise emitted to the environment are also investigated using a dot-pattern visualization. The study concludes that the modified tip configurations have a marked effect on tip-leakage vortex formation by altering the near-wall fluid paths on blade surfaces. The reduction in rotor noise emission is correlated with the control of tip-leakage flows produced by the tip end-plates.
A random decrement technique for operational modal analysis in the presence of periodic excitations
Authors: Asayesh M , Khodabandeloo B , Siami A
Published: March 2009

Operational modal analysis (OMA) is a procedure that allows the identification of the modal parameters of a structure using measured responses to unknown excitation. OMA techniques are based on the assumption that the input to the structure is stationary white noise. One of the OMA techniques, which is based on the assumption of a zero mean Gaussian white noise excitation, is the random decrement (RD) technique. In many practical cases, however, periodic excitation is often present in addition to the white noise. In this study, a method based on the concept of RD transformation is proposed to extract the response of a structure to the random input from the measured response that is due to both random and periodic excitations. Applying the RD method to the extracted random response, RD signatures were estimated. Modal parameters were estimated from RD signatures using the Ibrahim time domain algorithm. It is assumed that the period of the periodic excitation is known a priori. To verify the applicability of the method, a numerical simulation of a discrete two-degrees-of-freedom (DOF) dynamic system with a viscous damping is carried out. The results of this method were also compared with the results obtained from the enhanced frequency domain decomposition method. The efficiency of the proposed method, in the cases where the frequencies of harmonic components of periodic excitation are located at the natural frequencies of the system, is also evaluated.
Experimental study of check valves performances in fluid transient
Authors: Lee T S , Low H T , Nguyen D T , Neo W R A
Published: March 2009

An experimental set-up was introduced to study the dynamic behaviour of different types of check valves under pressure transient conditions. Three types of transient comparison methods were used, with similar results being obtained from all three methods. The experimental results show that the check valves with low inertia, assisted by springs or small travelling distance/angle, gave better performance under pressure transient conditions as compared to check valves without these features. Although different amounts of air entrainment were found to affect the experimental readings, the general characteristics of each check valve remain the same when compared between valves. This study can be applied to help in the choosing of suitable check valves for a particular pumping system.
Influence of load regime change on railway vehicle solid wheel reliability
Authors: Milutinović D
Published: March 2009

This paper analyses the influence of mechanical loads on railway vehicle solid wheel reliability. Reliability calculations is carried out according to the specifically set methodology — reliability is calculated according to the data about working loads and critical stress distribution. The influences on solid wheel reliability that are analysed are the following: standard deviation of lateral force distribution and mathematical expectation and standard deviation of the vertical force.
Biomedical engineering education at Politecnico di Milano: Development and recent changes
Authors: Baselli G
Published: March 2009

The biomedical engineering (BME) programme at the Politecnico di Milano (POLIMI) is characterized by a strong interdisciplinary background in a broad range of engineering subjects applied to biology and medicine. Accordingly, the undergraduate level (3 years) provides a general education, which includes mechanics, chemistry and materials, electronics, and information technology both in the context of general engineering and within BME foundations. In contrast, the postgraduate programme (2 years) offers a broad choice of specializations in BME fields in close connection with the BME research activities and laboratories of the campus and with active interchange with the other engineering disciplines. The history of BME development at POLIMI is briefly recalled, together with the characteristics of educational and research work, which is strongly biased by a large polytechnic university with no medical school within the same campus; points of strength and weakness due to this background are discussed. The introduction of a double cycle (undergraduate and postgraduate) according to the Bologna process (2000) and the effects on the programme structure is considered. An early phase in which professional education was emphasized at undergraduate level is recalled, which was followed by the actual revision fostering basic engineering and BME education at the first level while leaving in-depth specialization to postgraduate studies or to on-the-job training.
A study of the vane dynamics in a rotary vane expander for the transcritical CO2 refrigeration cycle
Authors: Yang B , Peng X , Sun S , Guo B , Xing Z
Published: March 2009

Because of the loss of contact between the vane tip and the cylinder wall, excessive gas leakage existed in the rotary vane expander, which was developed to replace the throttling valve to improve the coefficient of performance of the transcritical CO2 refrigeration cycle. The mathematical model of the vane dynamics was established to analyse the vane movement in two different cases depending on whether the vane contacted the cylinder wall or not. From the recorded pressures, instead of assumed ones in the slots, the forces acting on the vane were analysed and the vane movement in the slot, as well as the contact state between the vane and the cylinder wall, was described quantitatively. The dynamics model was validated with the vane movement data recorded by a high-speed video. The results showed that the two adjacent vanes presented different movement behaviours. Both vanes left the cylinder wall because of the impact of the charging gas, but while one vane could rebound quickly back to and maintain contact with the cylinder wall, the adjacent vane did not contact the cylinder wall throughout most of the angles until the rotation angle reached ∼ 70°. Arranging springs in the slot underneath the vane proved to be beneficial in maintaining a tight contact between the vane and the cylinder wall and thus improve the working processes of the expander. Compared with the gas forces on the vane, the centrifugal force was much smaller and therefore had negligible influence on the vane movement.
Study of the delivery behaviour of a pump for common rail fuel injection equipment
Authors: Giuffrida A , Ficarella A , Laforgia D
Published: March 2009

This work deals with the delivery flowrate of a radial piston pump for common rail fuel injection equipment. At first, attention is paid to the volumetric efficiency of the pump, presenting basic formulas and reviewing common theory. A new efficiency model is proposed and considerations regarding the pump running under large pressure differences between suction and delivery and variable driving speeds are formulated in order to realize difficulties in pump filling. Later, a numerical model simulating the working behaviour of the pump is used to investigate the effects of variable inlet pressures under high delivery pressure and different driving speeds. Comparisons between numerical results and experimental data referring to the delivery behaviour of the pump are reported, as well as in-cylinder pressure diagrams, necessary to realize filling deficiencies quickly.

The flowrate delivered by the investigated pump depends on both the inlet and outlet pressures. Increasing the driving speed beyond certain values does not result in proportional flowrate at pump delivery.
Robust control for overhead cranes by partial state feedback
Authors: Uchiyama N
Published: March 2009

This note presents a controller design for overhead cranes that provides robustness with respect to changes in rope length and transported mass. Elsewhere it has been recommended that the rope angular velocity feedback gain should be assigned to zero in linear quadratic (LQ) controller design. In this study, the gain is assigned to zero from another viewpoint, and hence the proposed controller is a partial state feedback controller. The proposed method provides a robust controller design without iterative computations. Simulation results demonstrate the effectiveness of the proposed design.
Self-tuning quantitative feedback theory for parallel force/position control of electro-hydrostatic actuators
Authors: Truong D Q , Ahn K K
Published: March 2009

Hydraulic power systems and actuators play an important role in modern industry because they have many advantages over other technologies with electric motors, high durability, and the ability to produce large force at high speeds. In order to improve the control performance of electro-hydrostatic actuators, the aim of this paper is to propose a novel parallel control strategy based on the self-tuning quantitative feedback theory (STQFT) technique and then applying it to control force and position of a new kind of hydraulic experimental system - the electro-hydrostatic load simulator (EHLS). The EHLS is very useful to test the force or/and position control of electro-hydrostatic actuators (EHAs). The STQFT controller is designed to satisfy the robust criterions based on the QFT technique. Then the parameters of the STQFT force and position controller are automatically tuned online to minimize the system error by using the gradient descent method and speed up convergence. Consequently, the EHLS using the novel controller is able to obtain the force and position control performance with high precision in a wide range of working conditions including perturbations. Experiments are carried out to evaluate the effectiveness of the proposed parallel force and position control method applied to the EHLS system.
A robust H2/H∞ control approach to uncertain systems with time-varying delays
Authors: Mahmoud M S , Ali A K M
Published: March 2009

An efficient descriptor approach is developed to solving the robust mixed
Predictive modelling of surface roughness and tool wear in solid lubricant assisted turning of AISI 1040 steel
Authors: Krishna Vamsi P , Rao D N , Srikant R R
Published: March 2009

This article focuses on developing empirical models for tool wear and surface roughness prediction in the solid lubricant assisted turning process. Solid lubricant suspensions like graphite and boric acid in SAE 40 oil are employed in the turning of AISI 1040 (EN 8) steel. Results indicate that surface roughness is improved by reducing cutting forces and tool flank wear as compared to dry and wet machining. A comparison of predicted values from the empirical models and measured values is also carried out.
Effects of friction modifiers on Pb-free plain bearing lubrication
Authors: Katafuchi T , Kasai M
Published: March 2009

In order to improve fuel efficiency for automotive engines, decreasing oil viscosity and using friction modifiers (FMs) for engine oil have been widely used. On the other hand, the reduction of lead, which has been used for plain bearings in engines, is also advanced from the perspective of reducing environmental pollutants. Therefore, whether FMs contained in engine oil were effective even for lead-free plain bearings was investigated.

In total, four kinds of bearing materials were tested. Two of them are Cu alloy on which Bi overlay was applied. Others are Al alloy on which Bi overlay was also applied. Two kinds of ashless FMs with and without sulphur were used as representatives of ashless ester-type FMs. As a result, the FMs with and without sulphur are effective, respectively, for Al alloy and Cu alloy plain bearings. They were also effective in preventing metal contact between the shaft and the plain bearing. This suggests that the interaction between the FM and the plain bearing material increased the oil film thickness between the shaft and the plain bearing.
Preparation and tribological properties of WS2 nanoparticles modified by trioctylamine
Authors: Wu J F , Zhai W S , Jie G F
Published: March 2009

Tungsten disulphide nanoparticles with diameters of about 200 nm modified by extractant trioctylamine (TOA) have been successfully prepared via an extraction-solvothermal method at a relative lower temperature. TOA was first saturated with 1 mol/l vitriol (H2SO4) aqueous solution, and then
Comparison of parametric and profilometric surface analysis methods on machined surfaces
Authors: Böhm J , Jech M , Vorlaufer G , Vellekoop M
Published: March 2009

In this work, a comparison of three different methods for analysing topographies and roughness on machined metal surfaces is presented. To obtain comparable results, the measurements were done on one and the same set of samples. For this purpose, an atomic force microscope (AFM), a confocal white light microscope, and a scattering light system were used to analyse the topography of samples of the same material, but with the topographies occurring step by step from the grinding process to the polishing process. Based on the results of the investigations with the parametric system (scattering light sensor) and the profilometric systems (AFM, confocal white light microscope), we established a correlation between the roughness parameters and the scattering light parameter. It is shown that the different methods lead to different roughness parameters of the same surface.
Continuous impact/abrasion testing: Influence of testing parameters on wear behaviour
Authors: Badisch E , Kirchgaßner M , Franek F
Published: March 2009

In many fields of industry, erosion is the dominant wear mechanism that reduces the lifetime of costly machine parts such as crushers, hammer bars, or cutting edges. Particles of specific mechanical and geometrical properties hit the surface with a certain energy and, under different angles of impact, cause abrasion and surface fatigue, or, in the case of high single particle impact energy, immediate damage by exceeding the rupture strength. Different types of wearfacing alloy layers applied through welding are used to protect exposed surfaces. The structure of state-of-the-art welding alloys is always based on multi-phase systems containing effective hard phases based mainly on borides and carbides of W, Cr, Nb, and others.

Within this work the so-called continuous impact abrasion test was established to compare different wearfacing alloys as described above and to develop a relation between parameters of the tribological system and properties of multi-phase materials. In the first step, morphology, energy, and size of the abrasive particles were varied and applied onto two different Fe-based wearfacing alloys. Observations on the phenomena of wear on the test samples accompanied by a quantitative evaluation of volumetric wear loss finally resulted in defining a model that enables a prognosis oriented consideration of wear. It was found within this study that wear phenomena in the microstructure have to be clearly differentiated according to the total energy applied and the impact energy of a single particle.
Fundamentals of optimizing aluminium-based journal bearing materials
Authors: Grün F , Gódor I , Eichlseder W
Published: March 2009

In this article, a test methodology of model scale is used to visualize the processes taking place during operation and subsequent breakdown in the boundary layer of journal bearing materials. The investigated materials are alloys of aluminium (Al99.6, AlSn20Cu, AlSn40) and tin (SnSb7.5Cu3.5). The utilized test configuration is based on a ring-on-disc system. The employed seizure test procedure was designed in previous studies. The tribometric results clearly show differences in the tribological behaviour between the materials. A series of tests are carried out to explain the observed differences. The frictional surfaces and microsections are observed using microscopy and microindentation. Pure aluminium is characterized both by a potentially low coefficient of friction and an unforgiving overload behaviour. This is due to the fact that components based on pure aluminium tend to lose system stability spontaneously. As more of the soft-phase Sn is added to the matrix, the emergency running properties improve. The system behaves less erratically and the overload behaviour improves. However, the mechanical strength and the wear resistance drop. Tribological functional models summarize the results of tribometrics and damage analysis. These models are the key to further optimization of the materials.
An exploration of the elastohydrodynamic— hydrodynamic transition through film thickness measurements in rolling point contacts
Authors: Dalmaz G , Chaomleffel J-P , Vergne P
Published: March 2009

The numerical solution of the elastohydrodynamic lubrication (EHL) problem is often presented in charts where dimensionless parameters and asymptotic relationships are used. Among them, the so-called isoviscous rigid asymptote is especially interesting because it defines the transition between elastohydrodynamic and hydrodynamic regimes, or between piezoviscous—elastic and isoviscous—rigid problems, respectively. In other respects, the combination of moderate contact pressures (i.e. moderate piezoviscosity, low normal load, and/or large radii of curvature) and high viscosity and speeds (i.e. high hydrodynamic effect) is quite often found in working mechanisms, for instance in most flange contacts in roller bearings. Surprisingly, only a few papers have analysed and discussed these operating conditions.

Based on experimental results obtained in the range of the Moes parameters 15< L<50 and 2< M<160 for pure rolling circular point contacts, the aim of this work is first to show how film thickness distributions are affected when the piezoviscous elastic to isoviscous rigid transition is approached. In this context, the relative values taken by the central and minimum film thicknesses will be particularly studied. The second objective is to compare our results with those predicted by elastohydrodynamic and hydrodynamic solutions for non-conformal contacts found in the literature. Finally, the exploration of mild EHL is dealt with and a former publication in which electrohydrodynamic very thin films and highly loaded thick film regimes were studied is completed.
A tribological day
Authors: Dowson D
Published: March 2009

Most tribologists are concerned with engineering applications of their skills, yet little recognition is given to the many illustrations of effective solutions to friction, wear, and lubrication problems evident in our everyday lives. This view will be supported by examples encountered by most of us in a single day, with an open encouragement to all to add to the list.

Several of these examples are embedded in biotribology and many were reported before either tribology, in 1966, or biotribology, in 1970 and 1973, was formally defined.

It is hoped that this account of a typical … Tribological day in the life of … will expose some of the fascinating examples of tribology all around us.
A series—parallel redundant reliability system for cellular manufacturing design
Authors: Safaei N , Tavakkoli-Moghaddam R , Sassani F
Published: March 2009

This paper presents a novel, multi-objective mixed-integer programming model for designing a cellular manufacturing system (CMS) that minimizes the total cost and maximizes the overall system reliability. In general, it is impossible to avoid production interruptions while handling machine breakdowns. In this situation, changing the process route dynamically can provide a quick response to meet production requirements. By assuming alternative process plans for operation—part requirements, the concept of the ‘reliable route’ proposed in the literature is extended. In a redundant reliability system with a series—parallel configuration, each reliable route is associated with an operation of a part (i.e. an operation—part) as a parallel subsystem. This route consists of a number of units or alternative machines allocated to cells in such a way that parts are processed with the maximum reliability for a given period of time. When an alternative machine breaks down, unprocessed parts are transferred to the next predetermined machine on the reliable route in order to complete their processes. While the reliable route approach increases the overall system reliability, the operational costs of the system also increase. To assess the present proposed model as a useful decision tool for the manager, various numerical examples are solved and analysed. Finally, the related computational results are reported.
Collision Energy and Cone Voltage Optimisation for Glycopeptide Analysis
Authors: Krenyacz Judit , Drahos László , Vékey Károly
Published: March 2009

Instrument tuning commonly used for peptide analysis and for proteomics causes a high degree of fragmentation for glycopeptides. This results in a strongly biased glycosylation pattern. To obtain correct results for glycopeptides, both the cone voltage and the collision energy has to be reduced significantly. A suitable standard for tuning the instrument for glycopeptide analysis is aspartic acid (which fragments under similar conditions as glycopeptides); while low mass sugar fragments (for example, at 657.3 Da) are good indicators for the presence/absence of glycopeptide fragmentation.
Endocyclic versus Exocyclic Mechanisms for Methyl Migration in Protonated N,N′-Dimethylpropane-1,3-diamine
Authors: Waters Tom , O'Hair Richard A.J.
Published: March 2009

A recent paper has suggested that an endocyclic methyl transfer pathway occurs in competition with methylamine loss for protonated N,N-dimethylpropane-1,3-diamine under conditions of low-energy collision induced dissociation [X. Zhang, S. Yao and Y. Guo, Int. J. Mass Spectrom. 214, 277 (2008)]. However, such endocyclic methyl transfers appear to be unprecedented in the gas phase. Therefore, in order to gain additional insights into the competition between methylamine loss and methyl transfer in this system, DFT calculations were performed at the B3LYP/6-311+G(d,p) level of theory for a number of competing mechanisms. Three mechanisms were considered for loss of methylamine: (i) a 1,2-elimination reaction to give N-methylallylamine (TS = 276.7 kJ mol−1); (ii) a neighbouring group reaction to give N-methylazitidine (TS = 146.4 kJ mol−1); and (iii) a 1,3-hydride shift to give N-methyl-1-propylimine (TS = 248.5 kJ mol−1). Accordingly, the neighbouring group pathway is expected to be kinetically favoured and dominate under conditions of low-energy collision-induced dissociation. Similarly, three different mechanisms were considered for intramolecular methyl transfer: (i) the previously proposed endocyclic reaction involving backside attack with inversion of configuration (TS = 252.3 kJ mol−1); (ii) the previously proposed endocyclic reaction involving frontside attack with retention of configuration (TS = 272.4 kJ mol−1); (iii) a multi-step mechanism which combines the neighbouring group pathway for methylamine loss and combinations of SN2 and proton transfer reactions within a series of ion–molecule complexes (highest TS = 201.7 kJ mol−1). These results suggest that the alternative pathway proposed here for methyl transfer should be preferred under conditions of low energy collision-induced dissociation.