bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical significance of low levels of minimal residual disease at the end of remission induction therapy in childhood acute lymphoblastic leukemia
Authors: Stow Patricia , Key Laura , Chen Xiaohua , Pan Qiulu , Neale Geoffrey A. , Coustan-Smith Elaine , Mullighan Charles G. , Zhou Yinmei , Pui Ching-Hon , Campana Dario
Published: March 2010

Minimal residual disease (MRD) at the end of remission-induction therapy predicts relapse in acute lymphoblastic leukemia (ALL). We examined the clinical significance of levels below the usual threshold value for MRD positivity (0.01%) in 455 children with B-lineage ALL, using polymerase chain reaction amplification of antigen-receptor genes capable of detecting at least 1 leukemic cell per 100 000 normal mononucleated cells (0.001%). Of the 455 clinical samples studied on day 46 of therapy, 139 (30.5%) had MRD 0.001% or more with 63 of these (45.3%) showing levels of 0.001% to less than 0.01%, whereas 316 (69.5%) had levels that were either less than 0.001% or undetectable. MRD measurements of 0.001% to less than 0.01% were not significantly related to presenting characteristics but were associated with a poorer leukemia cell clearance on day 19 of remission induction therapy. Patients with this low level of MRD had a 12.7% (± 5.1%; SE) cumulative risk of relapse at 5 years, compared with 5.0% (± 1.5%) for those with lower or undetectable MRD (P < .047). Thus, low levels of MRD (0.001%-< 0.01%) at the end of remission induction therapy have prognostic significance in childhood ALL, suggesting that patients with this finding should be monitored closely for adverse events.
Optimizing patient selection for myeloablative allogeneic hematopoietic cell transplantation in chronic myeloid leukemia in chronic phase
Authors: Pavlů Jiří , Kew Andrea K. , Taylor-Roberts Beatrice , Auner Holger W. , Marin David , Olavarria Eduardo , Kanfer Edward J. , MacDonald Donald H. , Milojkovic Dragana , Rahemtulla Amin , Rezvani Katayoun , Goldman John M. , Apperley Jane F. , Szydlo Richard M.
Published: March 2010

Outstanding results have been obtained in the treatment of chronic myeloid leukemia (CML) with first-line imatinib therapy. However, approximately 35% of patients will not obtain long-term benefit with this approach. Allogeneic hematopoietic stem cell transplantation (HCT) is a valuable second- and third-line therapy for appropriately selected patients. To identify useful prognostic indicators of transplantation outcome in postimatinib therapeutic interventions, we investigated the role of the HCT comorbidity index (HCT-CI) together with levels of C-reactive protein (CRP) before HCT in 271 patients who underwent myeloablative HCT for CML in first chronic phase. Multivariate analysis showed both an HCT-CI score higher than 0 and CRP levels higher than 9 mg/L independently predict inferior survival and increased nonrelapse mortality at 100 days after HCT. CML patients without comorbidities (HCT-CI score 0) with normal CRP levels (0-9 mg/L) may therefore be candidates for early allogeneic HCT after failing imatinib.
Nitroprusside modulates pulmonary vein arrhythmogenic activity
Authors: Lin Yung-Kuo , Lu Yen-Yu , Chen Yao-Chang , Chen Yi-Jen , Chen Shih-Ann
Published: March 2010

Background

Pulmonary veins (PVs) are the most important sources of ectopic beats with the initiation of paroxysmal atrial fibrillation, or the foci of ectopic atrial tachycardia and focal atrial fibrillation. Elimination of nitric oxide (NO) enhances cardiac triggered activity, and NO can decrease PV arrhythmogensis through mechano-electrical feedback. However, it is not clear whether NO may have direct electrophysiological effects on PV cardiomyocytes. This study is aimed to study the effects of nitroprusside (NO donor), on the ionic currents and arrhythmogenic activity of single cardiomyocytes from the PVs.

Methods

Single PV cardiomyocytes were isolated from the canine PVs. The action potential and ionic currents were investigated in isolated single canine PV cardiomyocytes before and after sodium nitroprusside (80 μM,) using the whole-cell patch clamp technique.

Results

Nitroprusside decreased PV cardiomyocytes spontaneous beating rates from 1.7 ± 0.3 Hz to 0.5 ± 0.4 Hz in 9 cells (P < 0.05); suppressed delayed afterdepolarization in 4 (80%) of 5 PV cardiomyocytes. Nitroprusside inhibited L-type calcium currents, transient outward currents and transient inward current, but increased delayed rectified potassium currents.

Conclusion

Nitroprusside regulates the electrical activity of PV cardiomyocytes, which suggests that NO may play a role in PV arrhythmogenesis.
Donor-host mitochondrial compatibility improves efficiency of bovine somatic cell nuclear transfer
Authors: Yan Zhong-hai , Zhou Yi-ye , Fu Jing , Jiao Fei , Zhao Lei-wen , Guan Peng-fei , Huang Shu-zhen , Zeng Yi-tao , Zeng Fanyi
Published: March 2010

Background

The interaction between the karyoplast and cytoplast plays an important role in the efficiency of somatic cell nuclear transfer (SCNT), but the underlying mechanism remains unclear. It is generally accepted that in nuclear transfer embryos, the reprogramming of gene expression is induced by epigenetic mechanisms and does not involve modifications of DNA sequences. In cattle, oocytes with various mitochondrial DNA (mtDNA) haplotypes usually have different ATP content and can further affect the efficiency of in vitro production of embryos. As mtDNA comes from the recipient oocyte during SCNT and is regulated by genes in the donor nucleus, it is a perfect model to investigate the interaction between donor nuclei and host oocytes in SCNT.

Results

We investigated whether the in vitro development of reconstructed bovine embryos produced by SCNT would be influenced by mtDNA haplotype compatibility between the oocytes and donor cells. Embryos from homotype A-A or B-B showed significantly higher developmental ability at blastocyst stages than the heterotype A-B or B-A combinations. Post-implantation development ability, pregnancy rate up to day 90 of gestation, as well as percent of term births were higher in the homotype SCNT groups than in the heterotype groups. In addition, homotype and heterotype SCNT embryos showed different methylation patterns of histone 3-lysine 9 (H3K9) genome-wide and at pluripotency-related genes (Oct-4, Sox-2, Nanog).

Conclusion

Both histone and DNA methylation show that homotype SCNT blastocysts have a more successful epigenetic asymmetry pattern than heterotype SCNT blastocysts, which indicates more complete nuclear reprogramming. This may result from variability in their epigenetic patterns and responses to nuclear reprogramming. This suggests that the compatibility of mtDNA haplotypes between donor cells and host oocytes can significantly affect the developmental competence of reconstructed embryos in SCNT, and may include an epigenetic mechanism.
Prevalence of inflammatory bowel disease in two districts of Sri Lanka: a hospital based survey
Authors: Niriella Madunil A , De Silva Arjuna P , Dayaratne Asangi HGK , Ariyasinghe Madurangi HADP , Navarathne Metthanandha MN , Peiris Ranjith SK , Samarasekara D Nandadeva , Satharasinghe Raveendra L , Rajindrajith Sharman , Dassanayake Anuradha S , Wickramasinghe A Rajitha , de Silva H Janaka
Published: March 2010

Background

Inflammatory bowel disease (IBD) is being increasingly diagnosed in Asia. However there are few epidemiological data from the region.

Methods

To determine prevalence and clinical characteristics of IBD, a hospital-based survey was performed in the Colombo and Gampaha districts (combined population 4.5 million) in Sri Lanka. Patients with established ulcerative colitis (UC) and Crohn's disease (CD), who were permanent residents of these adjoining districts, were recruited from hospital registries and out-patient clinics. Clinical information was obtained from medical records and patient interviews.

Results

There were 295 cases of IBD (UC = 240, CD = 55), of which 34 (UC = 30, CD = 4) were newly diagnosed during the study year. The prevalence rate for UC was 5.3/100,000 (95% CI 5.0-5.6/100,000), and CD was 1.2/100,000 (95% CI 1.0-1.4/100,000). The incidence rates were 0.69/100,000 (95% CI 0.44-0.94/100,000) for UC and 0.09/100,000 (95% CI 0.002-0.18/100,000) for CD. Female:male ratios were 1.5 for UC and 1.0 for CD. Mean age at diagnosis was (males and females) 36.6 and 38.1y for UC and 33.4 and 36.2y for CD. Among UC patients, 51.1% had proctitis and at presentation 58.4% had mild disease. 80% of CD patients had only large bowel involvement. Few patients had undergone surgery.

Conclusions

The prevalence of IBD in this population was low compared to Western populations, but similar to some in Asia. There was a female preponderance for UC. UC was mainly mild, distal or left-sided, while CD mainly involved the large bowel.
Yeast functional screen to identify genetic determinants capable of conferring abiotic stress tolerance in Jatropha curcas
Authors: Eswaran Nalini , Parameswaran Sriram , Sathram Balaji , Anantharaman Bhagyam , Kumar G Raja Krishna , Tangirala Sudhakar Johnson
Published: March 2010

Background

Environmentally inflicted stresses such as salinity and drought limit the plant productivity both in natural and agricultural system. Increasing emphasis has been directed to molecular breeding strategies to enhance the intrinsic ability of plant to survive stress conditions. Functional screens in microorganisms with heterologous genes are a rapid, effective and powerful tool to identify stress tolerant genes in plants. Jatropha curcas (Physic nut) has been identified as a potential source of biodiesel plant. In order to improve its productivity under stress conditions to benefit commercial plantations, we initiated prospecting of novel genes expressed during stress in J. curcas that can be utilized to enhance stress tolerance ability of plant.

Results

To identify genes expressed during salt tolerance, cDNA expression libraries were constructed from salt-stressed roots of J. curcas, regulated under the control of the yeast GAL1 system. Using a replica based screening, twenty thousand yeast transformants were screened to identify transformants expressing heterologous gene sequences from J. curcas with enhanced ability to tolerate stress. From the screen we obtained 32 full length genes from J. curcas [GenBank accession numbers FJ489601-FJ489611, FJ619041-FJ619057 and FJ623457-FJ623460] that can confer abiotic stress tolerance. As a part of this screen, we optimized conditions for salt stress in J. curcas, defined parameters for salt stress in yeast, as well as isolated three salt hypersensitive yeast strains shs-2, shs-6 and shs-8 generated through a process of random mutagenesis, and exhibited growth retardation beyond 750 mM NaCl. Further, we demonstrated complementation of the salt sensitive phenotypes in the shs mutants, and analyzed the expression patterns for selected J. curcas genes obtained from the screen in both leaf and root tissues after salt stress treatments.

Conclusions

The approach described in this report provides a rapid and universal assay system for large scale screening of genes for varied abiotic stress tolerance within a short span of time. Using this screening strategy we could isolate both genes with previously known function in stress tolerance as well as novel sequences with yet unknown function in salt stress tolerance from J. curcas. The isolated genes could be over-expressed using plant expression system to generate and evaluate transgenic plants for stress tolerance as well as be used as markers for breeding salt stress tolerance in plants.
Hormonal Profile Heterogeneity and Short-Term Physical Risk in Restrictive Anorexia Nervosa
Authors: Estour Bruno , Germain Natacha , Diconne Eric , Frere Delphine , Cottet-Emard Jean-Marie , Carrot Guy , Lang Francois , Galusca Bogdan
Published: March 2010

Context: The relevance of hormonal assessment in anorexia nervosa (AN) management is still unclear. The short-term physical risk during undernutrition period of the disease is partially predicted by anthropometric and electrolytic parameters.

Objective: The objective of the study was to evaluate hormonal profiles in a large cohort of AN and their relationship with critical states.

Design and Setting: This was an observational monocentric cross-sectional study performed in the endocrinological unit.

Patients and Other Participants: Participants included 210 young female subjects with restrictive-type AN and 42 female controls of comparable age.

Main Outcome Measures: The following hormonal parameters were measured: thyroid hormones, GH, IGF-I, cortisol, oestradiol, FSH, LH, SHBG, dehydroepiandrosterone sulfate, plasma metanephrines, and bone markers. Their relation with registered short-term evolution of AN subjects after hormonal assessment was evaluated.

Results: Except for metanephrines and dehydroepiandrosterone sulfate, most of the hormonal abnormalities previously reported in AN were confirmed. The manifestation of these hormonal abnormalities started below different body mass index (BMI) levels, ranging between 17 and 15 kg/m2, even though an important percentage of normal values for every parameter was still noticed for very low BMIs. All patients who developed critical states during the 3 months after the hormonal assessment presented with BMI less than 15 kg/m2 and a very increased level of cortisol, GH, and increased values of metanephrines.

Conclusions: The hormonal response to undernutrition is heterogeneous in a large population with restrictive AN. In clinical practice, metanephrines, GH, and/or cortisol data could be used as important predictors for severe short-term outcome.
Increased Sclerostin Serum Levels Associated with Bone Formation and Resorption Markers in Patients with Immobilization-Induced Bone Loss
Authors: Gaudio Agostino , Pennisi Pietra , Bratengeier Cornelia , Torrisi Venerando , Lindner Brigitte , Mangiafico Roberto A. , Pulvirenti Ivana , Hawa Gerhard , Tringali Giovanni , Fiore Carmelo E.
Published: March 2010

Context: Sclerostin, a Wnt signaling antagonist on the osteoblasts produced by osteocytes, is regulated by mechanical strain and is implicated in the pathogenesis of disuse bone loss. There are no data on sclerostin in humans.

Objective: The aim of the study was to evaluate sclerostin in patients immobilized after stroke, compared with control subjects, and to analyze its relationship with markers of bone formation and resorption.

Design: This was a cross-sectional study.

Setting and patients: We studied 40 postmenopausal women immobilized after a single episode of stroke 6 months or longer after onset, and 40 postmenopausal women from the general community. Bone status was assessed by quantitative ultrasound measurements at the calcaneus. Bone alkaline phosphatase (b-AP), carboxy-terminal telopeptide of type I collagen (CrossLaps), and sclerostin were evaluated by ELISA. We also used ELISA to measure serum levels of Dickkopf-1, another soluble inhibitor of Wnt/β-catenin signaling, highly expressed by osteocytes.

Results: Immobilized patients had higher sclerostin serum levels (median 0.975 ng/ml; 25th to 75th percentiles 0.662–1.490) than controls (median 0.300 ng/ml; 25th to 75th percentiles 0.165–0.400: P < 0.0001) and an increased bone turnover with a more significant rise in bone resorption (CrossLaps) than formation (b-AP) markers. Sclerostin correlated negatively with b-AP (r = −0.911; P < 0.0001) and positively with CrossLaps (r = 0.391; P = 0.012). Dickkopf-1 did not significantly differ between the groups. Patients also had quantitative ultrasound measurements index lower than controls (P < 0.001).

Conclusions: This study shows for the first time that long-term immobilized patients present hypersclerostinemia associated with reduced bone formation, and suggests that sclerostin could be a link between mechanical unloading and disuse osteoporosis in humans.
The Rules of DNA Recognition by the Androgen Receptor
Authors: Denayer Sarah , Helsen Christine , Thorrez Lieven , Haelens Annemie , Claessens Frank
Published: March 2010

The androgen receptor (AR) and glucocorticoid, progestagen, and mineralocorticoid receptors all recognize classical DNA response elements that are organized as inverted repeats of 5′-AGAACA-3′-like motifs with a three-nucleotide spacer. Next to such elements, the AR also recognizes a second type of androgen response element (ARE), the so-called selective AREs, which resemble more the direct repeats of the same hexamer. In this work, we show that not only the AR but also the progestagen receptor can recognize the selective AREs, whereas neither glucocorticoid nor mineralocorticoid receptor can. Recently, genomic AR-binding fragments have been postulated to contain AR-binding sites that diverge considerably from the classical ARE consensus. Extensive mutational analyses of these candidate motifs, however, reinstalls the values of the consensus sequence for the AREs as mentioned above, the importance of their dimeric nature and the presence of exactly three-nucleotide spacing. We developed a position-specific probability matrix that was used to predict with higher accuracy new AREs in different AR-binding regions. So far, all AR-binding genomic fragments that were analyzed contain AREs defined as receptor-dimer binding motifs with the ability to confer responsiveness to a reporter gene.
X-ray diffraction characteristics of five materials for stress measurement
Authors: Zhang Y-L , Liu J-Y , Wang J , Zeng Y-J
Published: March 2010

This paper presents the laboratory X-ray diffraction characteristics of five materials: carbon steel (Q235), austenitic stainless steel (1Cr18Ni9Ti), martensitic stainless steel (A335P92), Al alloy (LY12), and Ti alloy (TA15) in X-ray diffraction stress measurement. The difficulty in accurately determining actual stress is illustrated by two diffraction peaks with low diffraction intensity that occur in laboratory X-ray diffraction stress measurement. Stress measurements by both laboratory X-ray diffraction and strain gauges methods were conducted by using uniform strength beams of the five materials. A comparison between measured results and analytical/theoretical results was made to examine laboratory X-ray diffraction characteristics of the five materials for stress measurement. The measurements show that austenitic stainless steel, Al alloy, and Ti alloy present two diffraction peaks in X-ray diffraction stress measurement. Although the CrKα diffraction peak of the {220} plane of austenitic stainless steel is apparent, the stress calculated from this peak does not represent the actual stress; however, the CrKβ diffraction peak of the {311} plane, in spite of the lower peak-back ratio, can be used to obtain the actual stress. For the Al alloy, only the CrKα peak of the {222} plane can represent the material's stress. Two diffraction peaks of the Ti alloy measured by CoK α radiation can be used to calculate its actual stress. Hence attention should be paid to which X-ray diffraction peaks can be used for actual stress determination.
A procedure for evaluating high residual stresses using the blind hole drilling method, including the effect of plasticity
Authors: Beghini M , Bertini L , Santus C
Published: March 2010

When the blind hole drilling method is used to evaluate high residual stresses in a metallic component, plastic relaxed strain can be produced in the hole region because of the stress concentration that causes the local stresses to reach yielding. By assuming a linear–elastic behaviour of the material, a significant error can result. The present paper analyses the phenomenon of the plasticity locally induced by the introduction of the hole and proposes a procedure to take into account its effects on the residual stress evaluation. The correcting procedure has been developed by elaborating a large database of elastic–plastic finite element analyses performed considering a wide range of material properties and testing parameters, including all the strain gauge rosettes commonly used. As plasticity induces non-linearity in the relationship between residual stress and relaxed strain, the superposition principle cannot be applied, so the correction is limited to uniform in-depth residual stress fields. However, four hole depths were considered and the related correcting procedures were provided. When variable through thickness residual stress is expected, and high residual stress is confined near the surface region, the correction procedure can be applied to an initial limited depth.
Three-Dimensional Strain Analysis of Single-Lap Bolted Joints in Thick Composites Using Fibre-Optic Gauges and the Finite-Element Method
Authors: Restivo G , Marannano G , Isaicu G A
Published: March 2010

Bolted joints involving composite plates used to be almost entirely dedicated to aerospace applications. As the need for energy conservation has increased, the field of composite bolted joints has found new applications in ground armoured vehicles. Thick panels able to withstand large in-plane and impact loads are critical. The present investigation evaluates the interior strain field, through the thickness, of a composite plate connected to an aluminium panel with a single-lap bolted joint. The area of interest is the bearing plane region close to the hole because of the presence of stress concentrations that heavily modify the stress field. Experimental data for the bolted joint were recorded by fibre-optic strain gauges that were embedded in the bearing plane of the composite plate. Numerical analyses were performed using ANSYS as a pre-processor and LS-DYNA as a solver. The overall goal was to evaluate the magnitude of contact strains around the hole and through the thickness of the composite. These values were analysed and compared with the finite-element method results: the finite-element analysis correlated reasonably well with the experiments. An investigation of error causes was also carried out, in particular to evaluate the influence of incorrect gauge positioning and the effect of friction coefficients. General design considerations were finally provided, based on the complete three-dimensional finite-element analysis.
Predicting the forming limit diagram of AA 5182-O
Authors: Li B , Nye T J , Wu P D
Published: March 2010

The prediction of a forming limit diagram (FLD) for aluminium alloy sheet using finite element analysis without implementing pre-defined geometrical imperfections or material imperfections is studied. The limit strains of the FLD are determined by applying a new proposed localization criterion in the dome stretching test. The elements just outside the necking area, where their major and minor principal strains have no simultaneous change after localized necking happens, are chosen as the reference elements for measurement of limit strains. Simulations are carried out for various strain paths ranging from balanced biaxial stretching to uniaxial stretching. The predicted FLD of AA 5182-O is compared with an experimentally determined FLD and very good agreement is achieved. It is demonstrated that FLDs can be predicted by the finite element method without requiring any assumed geometric or material imperfections in the numerical model.
The mechanical behaviour of a symmetrical punch with compound curvature
Authors: Vázquez J , Sackfield A , Hills D , Domínguez J
Published: March 2010

The contact of a symmetrical, convex indenter having a large central radius of curvature, and smaller radii describing the edges, pressed into an elastic half plane is studied. It is first submitted to a normal load, later a tangential load is applied, and finally a global stress is applied to the semi-infinite medium. This type of indenter is used as the basis for a possible optimal contact design.
A kinematic investigation of a spherical involute bevel-geared system
Authors: Lee H W , Lee K O , Chung D H
Published: March 2010

This study gives an exact definition of the spherical involute curved face and the pitch azimuthal angle of a bevel-geared system. Using the coordinate-transformation method, it derives the kinematic relations between the operating pressure angles, pitch azimuthal angles, operating pitch cone angles, base cone angles, and pitch action angles. An exact spherical involute bevel gear illustrates that a spherical involute tooth profile can be modelled only if the operating pressure angle, operating pitch cone angle, number of teeth, and cone radius are given. The ratio of the angular speeds of the spherical involute bevel gear reveals that the comparison of a bevel gear with a cone friction wheel is similar to the situation in which a belt that is wound around a base cone becomes untied and is wound around the base cone of the other party. The findings confirm that even when the shaft angle changes, the ratio of angular speeds does not change. This study also exactly calculates the operating rate in an involute bevel gear in a theoretical manner. To review interchangeability, the study defines the angular pitch and the crown number of teeth and shows that the proposed spherical involute bevel gear possesses interchangeability. To verify the contact phenomenon of the spherical involute bevel gear, a computer-graphic verification is conducted on three models to see whether gear interference occurs when two gears are operating while going in gear with each other.
The characteristics of high power fibre laser welding
Authors: Salminen A , Piili H , Purtonen T
Published: March 2010

Laser welding has an ever growing role in manufacturing technology. Keyhole laser welding is the most important laser welding process in metal industry when exceeding the 1 mm weld penetration. This process uses efficiently the high energy density of a laser beam to vaporize and melt materials, thus producing a keyhole in the material via which the energy is brought to it. The requirements from customer side and the development of new materials have been giving justification for the development of new laser types suitable for material processing with ever higher power values. In contrast, the development of laser technologies has made it possible to build more powerful lasers with excellent beam properties and good electrical efficiency. New laser sources with good absorption and beam quality make the laser welding even more efficient when throughput and efficiency are considered. They show their ability to produce narrower welds with lower line energy. However, the validation of actual keyhole shape, size, and behaviour against the models is still lacking because of the difficulties in performing the measurements of the actual dimensions. It has been shown that the better the beam quality the higher the welding speed. When welding with high power, good beam quality, and wavelength close to 1000 nm, there are some obstacles to overcome, which are caused by high absorption and power density. Typically, problems, such as thermal lensing, can be avoided with proper parameter and tool selection. Typically, the size of the keyhole is according to the focal point size, and the stability of the keyhole plays a major role when considering the ability of the laser welding process to produce high quality welds.
Laser forming: Overview of the controlling factors in the temperature gradient mechanism
Authors: Edwardson S P , Griffiths J , Edwards K R , Dearden G , Watkins K G
Published: March 2010

Laser forming (LF) offers the industrial promise of controlled shaping of metallic and non-metallic components for prototyping, the correction of design shape or distortion, and precision adjustment applications. The potential process advantages include precise incremental adjustment, flexibility of application, and no mechanical ‘spring-back’ effect. To date, there has been a considerable amount of work carried out on two-dimensional LF, using multi-pass straight-line scan strategies to produce a reasonably controlled bend angle in a number of materials, including aerospace alloys. A key area, however, where there is a limited understanding, is the variation in the bend angle per pass during multi-pass temperature gradient mechanism-based LF along a single irradiation track, in particular, the decrease in the bend angle per pass after many irradiations for a given set of process parameters. Understanding this is essential if the process is to be fully controlled for a manufacturing environment. The research presented in this paper through empirical data and numerical simulation of the LF of sheet mild steel, Ti6Al4V and AA5251, by CO2 laser offers a novel coherent picture of the key influencing factors and at which point in the bend evolution each is dominant, which has not been presented before.
Torsional Sensors for Conical Shell in Torsional Vibrations
Authors: Li H , Chen Z B
Published: March 2010

This paper presents shear piezoelectric sensors for conical shell sensing. The piezoelectric patch is polarized in the longitudinal direction of conical shell structure. The electrodes are fixed at the sides parallel to the directions of polarization. Sensors in this arrangement are only sensitive to the in-plane shear strains. Both sensing equations and modal signals are derived based on the thin-shell assumption and piezoelectric effect. Numerical results are presented for free torsional vibrations of frustum shell of revolution with clamped-free boundary, and the effects of sensor length on the output are evaluated. The amplitudes of the output signal of the sensors are lower than that of modal ones, but they are all share the same trends. The amplitudes depend on the deformation of the shell and the length of the sensor. The results indicate the optimal locations of the piezoelectric sensor for sensing the torsional vibration of clamped-free shell. The output signals of the sensor can be used as the control input for later active vibration control. The sensing equations are applicable to sense shear strains and torsion of other type shells by replacing the strain equation.
Film thickness fluctuations in time-varying normal loading of rolling elastohydrodynamically lubricated contacts
Authors: Félix-Quiñonez A , Morales-Espejel G E
Published: March 2010

A simplified semi-analytical solution for the film thickness fluctuations in the normal-approach problem of elastohydrodynamic lubrication (EHL) contacts has been obtained. The model is based on an inlet analysis to include squeeze-film effects together with the variation of lubricant entrainment speed that is induced by the changes of contact radius as the load oscillates. The results obtained are in excellent agreement with numerical solutions and suggest that the fluctuations in entrainment speed are the main cause for the observed film modulations. The modified semi-analytical solution seems applicable in many practical cases. The amplitude of the film thickness fluctuations produced by fluctuations in the load is in this way related to a single parameter.
A Theoretical Formula for Predicting the Instantaneous Folding Force of the First Fold in a Single Cell Hexagonal Honeycomb under Axial Loading
Authors: Niknejad A , Liaghat G H , Moslemi Naeini H , Behravesh A H
Published: March 2010

This article calculates a theoretical formula to predict the instantaneous folding force of the first fold creation in a single cell hexagonal honeycomb under axial loading. For this purpose, the sum of dissipated energy rate under bending around horizontal and inclined hinge lines and that under extensional deformations was equated to the work rate of the external force on the column. The final formula reasonably predicts the instantaneous folding force of the first fold of the thin-walled hexagonal columns during the folding progress. Finally, according to the calculated theoretical relation, the instantaneous folding force of the hexagonal column versus the axial displacement was sketched, and the comparison to the experimental results showed a good correlation.
An Experimental and Analytical Investigation of a Prototype Isolation System for an Explosive Gas Operated Device and Interaction Force Estimation
Authors: Kim H-J
Published: March 2010

In this study, the optimal isolation system for the explosive gas operated device (EGOD) was investigated. Based on the analysis of the human body response induced by impulsive disturbances from the EGOD and the simplified human interaction model, a feasible isolation scheme has been presented and the prototype isolation system including the dynamic absorber has been constructed. In order to determine the parameters of that system, an optimization process was performed under constrained conditions. Finally, the performance of the designed prototype isolation system was evaluated in a series of experiments under actual utility condition, and the transmitted force from the EGOD to human body was predicted.
Laboratory investigation of some sanding parameters to improve the adhesion in leaf-contaminated wheel—rail contacts
Authors: Arias-Cuevas O , Li Z , Lewis R , Gallardo-Hernández E A
Published: March 2010

Leaf contamination has been identified as the major cause of low adhesion incidents occurring on some railway networks in the last few decades. In the presence of leaf layers, the trains cannot have the required adhesion at the wheel—rail contact for adequate traction and braking operation. Under these circumstances, not only the punctuality but also the safety of the railway transportation can be threatened. In order to mitigate low adhesion problems, railway organizations have opted for different measures, particularly during the season of Autumn. The most employed measure consists of bringing sand to the wheel—rail interface, which can be performed by means of air-pumped sanders or in the form of sand-based friction modifiers. Although sand has widely been accepted as an effective adhesion improver, the effect of some sanding parameters on the adhesion improvement in leaf-contaminated contacts seems to be unclear. This hinders the possible optimized use of sand on the railway networks. In this paper, the influence of the number of sanding axles, particle size of sand, and wheel slip on the adhesion recovery in leaf-contaminated wheel—rail contacts is presented. Rolling—sliding tests under closely controlled conditions have been performed on a twin-disc roller rig. An electrical circuit has been connected to the rig for monitoring the effect of contamination on the electrical conductivity across the wheel—rail contact. The results show that the application of sand contributes to removing the leaf layers from the disc surfaces, which leads to a higher adhesion coefficient in comparison with the untreated (baseline) situation. Accordingly, the electrical conductivity across the wheel—rail contact is also improved. Furthermore, the adhesion recovery is shown to become larger and faster with the increase in sanding axles and wheel slip. Among the particle sizes tested in this work, medium particles are found to yield the most effective adhesion recovery.
Mapping railway wheel material wear mechanisms and transitions
Authors: Lewis R , Dwyer-Joyce R S , Olofsson U , Pombo J , Ambrósio J , Pereira M , Ariaudo C , Kuka N
Published: March 2010

In order to develop more durable wheel materials to cope with the new specifications being imposed on wheel wear, a greater understanding of the wear mechanisms and transitions occurring in wheel steels is needed, particularly at higher load and slip conditions.

The aim of this work was to draw together current understanding of the wear mechanisms, regimes, and transitions (particularly with R8T wheel material) and new tests on R7T wheel material; to identify gaps in the knowledge; and to develop new tools for assessing wear of wheel materials, such as wear maps, that can be used to improve wear prediction. Wear assessment of wheel materials, as well as wear rates, regimes, and transitions, is discussed.

Twin disc wear testing, used extensively for studying wear of wheel and rail materials, has indicated that three wear regimes exist for wheel materials: mild, severe, and catastrophic. These have been classified in terms of wear rate and features. Wear rates are seen to increase steadily initially and then level off, before increasing rapidly as the severity of the contact conditions is increased.

Analysis of the contact conditions in terms of friction and slip has indicated that the levelling off of the wear rate observed at the first wear transition is caused by the change from partial slip to full slip conditions at the disc interface. Temperature calculations for the contact showed that the large increase in wear rates seen at the second wear transition may result from a thermally induced reduction in yield strength and other material properties. Comparisons made between discs and actual wheels have provided some support for the theories relating to the transitions observed.

Wear maps have been produced using the test results to study how individual contact parameters such as load and sliding speed influence wear rates and transitions. The maps are also correlated to expected wheel—rail contact conditions.

This improved understanding of wheel wear mechanisms and transitions will help in the aim of eventually attaining a wear modelling methodology reliant on material properties rather than on wear constants derived from testing.
Applying precast slab panel track to replace timber track in an existing steel plate girder railway bridge
Authors: Choi J-Y , Park Y-G , Choi E-S , Choi J-H
Published: March 2010

Timber track steel girder railway bridges in service for many decades have been damaged and deteriorated despite the regular scheduled maintenance owing to their structural characteristics, calling for alternatives to improve the structural safety and serviceability. In this study, the authors aim to develop precast slab panel (PSP) tracks to enhance the long-term workability and durability of existing bridges in service so as to improve the performance of conventional lines. Two full-scale specimens with a timber track and a PSP track were fabricated to evaluate the effects of the application of the PSP track, and static and dynamic tests were conducted. Also, a time-history analysis and a three-dimensional finite-element method analysis were performed to consider the train speed and the effect of multiple loads of train. From the results, the static and dynamic responses of the PSP track girder were significantly reduced, compared with the timber track girder.
Wheel-Rail Interface Management: A Rolling Stock Perspective
Authors: Fröhling R D , Hettasch G
Published: March 2010

This paper reports on tools and methods used to analyse and present information for long-, medium-, and short-term planning and fleet condition supervision to predict and manage wheel-rail performance. Challenges in addressing measuring accuracy and repeatability are also discussed.
Employee, manage thyself: The potentially negative implications of expecting employees to behave proactively
Authors: Bolino Mark , Valcea Sorin , Harvey Jaron
Published: March 2010

Previous research investigating proactive behaviour at work has generally focused on the ways in which proactive behaviour enables individuals and organizations to be more effective. Although it has been noted that some proactive behaviours may be undesirable or have potentially negative consequences, researchers have not examined the ‘dark side’ of proactive behaviour in any systematic way. In this conceptual paper, we explore the potentially negative individual and organizational implications of expecting employees to behave proactively. Specifically, at the individual level, we argue that expecting proactive behaviour in organizations may contribute to stress among employees and friction between proactive and less proactive employees. At the organizational level, we suggest that relying on proactive behaviour may cause harm to an organization by undermining its ability to socialize employees and foster its organizational culture, weakening its learning capability, and reducing its ability to develop future leaders. We conclude by discussing additional avenues for studies examining the potential costs of proactive behaviour for both individuals and organizations alike.
The larger N-heteroacenes
Authors: Bunz Uwe H. F.
Published: March 2010

The history and development of pyrazine- and pyridine-type heteroacenes and their use in solid-state organic electronics are discussed and reviewed. The larger N-heteroacenes are potential electron- or hole-transporting materials and should therefore complement acenes in organic electronics. As they feature electronegative nitrogen ring atoms in their molecular skeleton, issues with oxidation should be less problematic when comparing them to the larger acenes such as pentacene. This paper covers the synthesis and the solid-state packing of larger (tetracene/pentacene-based) N,N-heterocylic acenes as well as the question of the interplay of aromaticity and antiaromaticity in the known larger N-heteroacenes and their N,N-dihydro-derivatives; also illuminated are their optical properties. A literature overview is provided. Keywords: acenes; alkynes; heterocycles; organic chemistry; organic electronics.
Effect of molecular clips and tweezers on enzymatic reactions by binding coenzymes and basic amino acids
Authors: Klärner Frank-Gerrit , Schrader Thomas , Polkowska Jolanta , Bastkowski Frank , Talbiersky Peter , Campañá Kuchenbrandt Mireia , Schaller Torsten , de Groot Herbert , Kirsch Michael
Published: March 2010

The tetramethylene-bridged molecular tweezers bearing lithium methanephosphonate or dilithium phosphate substituents in the central benzene or naphthalene spacer-unit and the dimethylene-bridged clips containing naphthalene or anthracene sidewalls substituted by lithium methanephosphonate, dilithium phosphate, or sodium sulfate groups in the central benzene spacer-unit are water-soluble. The molecular clips having planar naphthalene sidewalls bind flat aromatic guest molecules preferentially, for example, the nicotinamide ring and/or the adenine-unit in the nucleotides NAD(P)+, NMN, or AMP, whereas the benzene-spaced molecular tweezers with their bent sidewalls form stable host–guest complexes with the aliphatic side chains of basic amino acids such as lysine and argenine. The phosphonate-substituted tweezer and the clips having an extended central naphthalene spacer-unit or extended anthracene and benzo[k]fluoranthene sidewalls, respectively, form highly stable self-assembled dimers in aqueous solution, evidently due to non-classical hydrophobic interactions. The phosphate-substituted molecular clip containing naphthalene sidewalls inhibits the enzymatic, ADH-catalyzed ethanol oxidation by binding the cofactor NAD+ in a competitive reaction. Surprisingly, tweezer-bearing phosphate substituents in the central benzene spacer-unit are more efficient inhibitors for the ethanol oxidation than the correspondingly substituted naphthalene clip, even though the tweezer does not bind the cofactor NAD+ within the limits of detection. The phosphate-substituted naphthalene clip is, however, a highly efficient inhibitor of the enzymatic oxidation of glucose-6-phosphate (G6P) with NADP+ catalyzed by glucose-6-phosphate dehydrogenase (G6PD), whereas the phosphonate-substituted clip only functions as an inhibitor by forming a complex with the cofactor. Detailed kinetic, thermodynamic, and computational modeling studies provide insight into the mechanism of these novel enzyme inhibition reactions.
Intramolecular triarylmethane-triarylmethylium complex: Generation, properties, and X-ray structure of a C–H bridged carbocation
Authors: Suzuki Takanori , Takeda Takashi , Yoshimoto Yasuyo , Nagasu Takayuki , Kawai Hidetoshi , Fujiwara Kenshu
Published: March 2010

A series of title carbocations was generated and isolated as stable salts. X-ray analyses revealed a preference for an unsymmetric structure in which the bridging hydrogen is localized on one of the two triarylmethane units. NMR spectroscopy showed a similar preference in solution. The bridging hydrogen fluctuates between the two chromophores in solution, and the energy barrier for the H shift is linearly correlated with the C···C+ separation determined by X-ray. According to an extrapolation, the energy barrier should decrease when the C···C+ separation is less than 2.7 Å, which suggests a new model for isolable pure organic species with a three-center–two-electron bond.
Electronic structure of higher acenes and polyacene: The perspective developed by theoretical analyses
Authors: Bettinger Holger F.
Published: March 2010

The hypothetical polymer obtained by linear annelation of benzene units, polyacene (PAC) (C4H2)n, has received considerable attention over the last 50 years. This interest is due to the unusual electronic structure that is assumed to result in usual physical properties. The review summarizes the theoretical investigations of PAC research. The most recent computational analyses available in the literature are based on density functional theory (DFT) for PAC and on the complete active space self-consistent field (CASSCF) method for oligoacenes and suggest an undistorted symmetrical structure with an antiferromagnetic (AFM) coupling of electrons.
Mastering nanostructured materials through H-bonding recognitions at interfaces
Authors: Mohnani Stefan , Llanes-Pallas Anna , Bonifazi Davide
Published: March 2010

The controlled engineering of functional architectures composed of π-systems with unusual opto-electronic properties is currently being investigated intensively from both fundamental research and technological application viewpoints. In particular, the exploitation of the supramolecular approach for the facile construction of multidimensional architectures, featuring cavities capable of hosting functional molecules, could be used in several applications, such as nanomedicine, molecular-based memory storage devices, and sensors. This paper highlights our recent strategies to use hydrogen-bonding interactions to prepare nanostructured functional architectures via the self-assembly of organic molecular modules studied at different interfaces.
Plasminogen hydrolysis by cathepsin S and identification of derived peptides as selective substrate for cathepsin V and cathepsin L inhibitor
Authors: Coppini Larissa P. , Barros Nilana M.T. , Oliveira Marcela , Hirata Izaura Y. , Alves Marcio F.M. , Paschoalin Thaysa , Assis Diego M. , Juliano Maria A. , Puzer Luciano , Brömme Dieter , Carmona Adriana K.
Published: March 2010

Plasminogen is a glycoprotein implicated in angiogenesis and fibrin clot degradation associated with the release of angiostatin and plasmin activation, respectively. We have recently reported that cathepsin V, but not cathepsins L, B, and K, can release angiostatin-like fragments from plasminogen. Here, we extended the investigation to cathepsin S which has been implicated in angiogenesis and tumor cell proliferation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of plasminogen hydrolysis by cathepsin S revealed generation of two fragments (60 and 38 kDa). Amino-terminal sequencing indicated that cleavage occurs at the Leu469-Leu470 peptide bond. In contrast to cathepsin V, which possesses antiangiogenic activity, cathepsin S plasminogen cleavage products were not capable of inhibiting angiogenesis on endothelial cells. Moreover, we explored the different selectivities presented by cathepsins V and S towards plasminogen and synthesized fluorescence resonance energy transfer peptides encompassing the hydrolyzed peptide bonds by both enzymes. The peptide Abz-VLFEKKQ-EDDnp (Abz=ortho-aminobenzoic acid; EDDnp= N-[2,4-dinitrophenyl]ethylenediamine), hydrolyzed by cath-epsin V at the Phe-Glu bond, is a selective substrate for the enzyme when compared with cathepsins B, L, and S, whereas Abz-VLFEKKVYLQ-EDDnp is an efficient cathepsin L inhibitor. The demonstrated importance of the S3′-P3′ interaction indicates the significance of the extended subsites for enzyme specificity and affinity.