bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Elastic-Plastic Static Friction Models to Rough Surfaces With Asymmetric Asperity Distribution
Authors: Lee Chul-Hee , Eriten Melih , Polycarpou Andreas A.
Published: July 2010

Asymmetric height distribution in surface roughness is important in many engineering surfaces, such as in constant velocity (CV) joints, where specific manufacturing processes could result in such surfaces. Even if the initial surfaces exhibit symmetric roughness, the running-in and sliding processes could result in asymmetric roughness distributions. In this paper, the effect of asymmetric asperity height distribution on the static friction coefficient is investigated theoretically and experimentally. The asymmetry of the surface roughness is modeled using the Pearson system of frequency curves. Two elastic-plastic static friction models, the Kogut–Etsion (KE) and Cohen–Kligerman–Etsion (CKE) models are adapted to account for asymmetric roughness and employed to obtain the tangential and normal contact forces. Static friction experiments using CV joint roller and housing surfaces, which exhibit different levels of surface roughness, were performed and directly compared with the KE and CKE static friction models using both a symmetric Gaussian as well as Pearson distributions of asperity heights. It is found that the KE model with the Pearson distribution compares favorably with the experimental measurements.
The Effect of Deformation Speed on Frictional Behavior by Tip Test
Authors: Jung Ki-Ho , Im Yong-Taek
Published: July 2010

In this study, a tip test was carried out under various ram velocities of 0.01 mm/s, 0.1 mm/s, 1.0 mm/s, and 5.0 mm/s to investigate the effect of deformation speed on friction using the commercially available AL6061-O. For experiments, four different lubrication conditions with grease, corn oil, VG100, and VG32 were used to investigate the lubrication characteristics. During the test, temperature was measured in the specimen by a K-type thermocouple to determine the temperature increase induced by heat generation due to plastic deformation. In the present investigation, the linearity between tip distance and experimentally measured maximum load was consistently observed in spite of different orders of ram velocity and types of lubrication. As the ram velocity increased, loads were reduced for liquid lubricants and increased for grease. To better understand such a lubrication phenomenon, white-light interferometer microscopy and laser confocal microscopy were used to observe and compare surface topographies on the bottom and circumferential side of the deformed specimens at various experimental conditions, which formed lubrication pockets incurring hydrodynamic pressure of liquid lubricants. Finally, the effect of deformation speed on the level of shear friction factors at the punch and die interfaces was characterized by the finite element simulations and was determined to be expressed as an exponential function depending on the lubricant. This investigation demonstrates the capability of the tip test to experimentally characterize the effect of deformation speed on the frictional behavior for practical use.
Comparison Between Elastic Foundation and Contact Force Models in Wear Analysis of Planar Multibody System
Authors: Mukras Saad , Kim Nam H. , Mauntler Nathan A. , Schmitz Tony , Sawyer W. Gregory
Published: July 2010

In this paper, two procedures to analyze planar multibody systems experiencing wear at a revolute joint are compared. In both procedures, the revolute joint of interest includes a clearance whose shape and size are dictated by wear. The procedures consist of coupled iterative analyses between a dynamic system analysis with nonideal joints and a wear prediction to determine the evolution of the joint clearance. In the first procedure, joint forces and contact pressures are estimated using the elastic foundation model with hysteresis damping via the dynamic analysis. In the second procedure, a contact force model with hysteresis damping is used to estimate the joint forces. In the latter case, however, the contact pressure is estimated using a finite element method (FEM). A comparison in performance of the two models is facilitated through the use of an experimental slider-crank mechanism in which wear is permitted to occur at one of the joints. It is observed that the two procedures provide similar estimates for the dynamic response and wear volumes but substantially different predictions on the wear profiles. Additionally, experimental results show that while predictions on the wear volume from both models are reasonably accurate, the FEM-based model produced more accurate predictions on the wear profile.
Plasto-Elastohydrodynamic Lubrication (PEHL) in Point Contacts
Authors: Ren Ning , Zhu Dong , Chen W. W. , Wang Q. Jane
Published: July 2010

Elastohydrodynamic lubrication (EHL) is an important branch of the lubrication theory, describing lubrication mechanisms in nonconformal contacts widely found in many mechanical components such as various gears, rolling bearings, cams and followers, metal-rolling tools, traction drives, and continuous variable transmissions. These components often transmit substantial power under heavy loading conditions. Also, the roughness of machined surfaces is usually of the same order of magnitude as, or greater than, the estimated average EHL film thickness. Consequently, most components operate in mixed lubrication regime with significant asperity contacts. Due to very high pressure concentrated in small areas, resulted from either heavy external loading or severe asperity contacts, or often a combination of both, subsurface stresses may exceed the material yield limit, causing considerable plastic deformation, which may not only permanently change the surface profiles and contact geometry but also alter material properties through work hardening as well. In the present study, a three-dimensional plasto-elastohydrodynamic lubrication (PEHL) model has been developed by taking into account plastic deformation and material work-hardening. The effects of surface/subsurface plastic deformation on lubricant film thickness, surface pressure distribution, and subsurface stress field have been investigated. This paper briefly describes the newly developed PEHL model and presents preliminary results and observed basic behavior of the PEHL in smooth-surface point contacts, in comparison with those from corresponding EHL solutions under the same conditions. The results indicate that plastic deformation may greatly affect contact and lubrication characteristics, resulting in significant reductions in lubricant film thickness, peak surface pressure and maximum subsurface stresses.
Surface Roughness Effects on Air Bearing Performance Over a Wide Range of Knudsen and Wave Numbers
Authors: White James
Published: July 2010

Design of a near contact air bearing interface such as that created by a recording head slider and data storage disk requires consideration of a lubrication equation that is appropriate for high Knudsen number flows. The Poiseuille flow database reported by Fukui and Kaneko, 1990 [“A Database for Interpolation of Poiseuille Flow Rates for High Knudsen Number Lubrication Problems,” ASME J. Tribol., 112, pp. 78–83] is appropriate over a wide range of Knudsen numbers and is used throughout the data storage industry for analysis of the low flying recording head slider air bearing. However, at such low clearances, the topography of the air bearing surfaces also comes into question, making it important to consider both rarefaction and surface roughness effects in the air bearing design. In order to simplify the air bearing analysis of rough surfaces, averaging techniques for the lubrication equation have been developed for situations where the number of roughness elements (or waves) is either much greater or much less than the gas bearing number. Between these two extremes there are currently no roughness averaging methods available. Although some analytical and numerical studies have been reported for continuum and first-order slip conditions with simple geometries, little or no results have appeared that include both surface roughness and high Knudsen number flows outside the limited ranges where surface averaging techniques are used. In order to better understand the influence of transverse surface roughness over a wide range of Knudsen numbers and the relationship of key parameters involved, this paper describes a primarily analytical air bearing study of a wide, rough surface slider bearing using the Poiseuille flow database reported by Fukui and Kaneko. The work is focused outside the limited ranges where current surface averaging methods for the lubrication equation are expected to be valid.
Thermodynamic Model of the Metallic Friction Process
Authors: Maciąg Maria
Published: July 2010

An energy model of stabilized friction and wear is presented. Heating of a definite mass of surface material to the flash point, in consideration of the mass’s specific heat and wear, is assumed to provide the basis for thermal processes. An energy balance is presented in the form of a first law of thermodynamics formula for open systems. Two new magnitudes, referred to as complex systemic constants C and D, are developed and their physical meaning is interpreted. These complex systemic constants are subsequently employed to describe the tribological system. Among other magnitudes in the model, density of thermal dissipation and enthalpy flux, power density of mechanical dissipation, wear severity, and specific work of wear are described. Friction and wear testing results [Ciecieląg, 1994, “Energy Conditions of Metal Resistance to Tribological Wear,” Ph.D. thesis, Świętokrzyska Technical University, Kielce; Żurowski, 1996, “Energy Aspect of Increasing Wear-Resistance of Metals in the Process of Engineering Dry Friction,” Ph.D. thesis, Świętokrzyska Technical University, Kielce; Sadowski and Żurowski, 1992, “Thermodynamic Aspects of Metals' Wear-Resistance,” Tribology and Lubrication Engineering, 3, pp. 152–159] are employed to describe, in quantitative terms, selected tribological systems on the basis of the presented thermodynamic model. A method of determining the complex systemic constants C and D is developed. Specific work of wear, wear severity, probability of emergence of a flux of tribological wear products, and relation of worn mass to heated mass and flash temperature as functions of temperature are defined. This paper concludes with application, significance, and advantages of the complex systemic constants C and D, and phenomena arising in frictional contact between two metals.
An Overview of the Hardness Differential Required for Abrasion
Authors: Pintaude Giuseppe
Published: July 2010

This paper presents an overview of the hardness differential required for abrasion. Empirically, the abrasive must be at least 1.2 times harder than the worn surface if it is to produce a scratch. This value has been determined theoretically using slip-line field modeling, which assumes rigid-plastic mechanical behavior, an assumption that is inadequate for most abrasive particles. Two approaches using elastic-plastic models and three tribological pairs with similar ratios of abrasive hardness to worn material hardness were tested to gain an understanding of the hardness differential required for abrasion. The analysis showed that the ratios of the property of the abrasive to the property of the worn surface did not change with the model used when the mechanical behavior of the materials was similar. However, when the behavior of the materials was very dissimilar—as is often the case in abrasive processes—the ratios varied greatly depending on the model used, showing that there is a need for models to describe the hardness differential required for abrasion.
CD4
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CD25
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Regulatory T Cell Depletion Improves the Graft-Versus-Tumor Effect of Donor Lymphocytes After Allogeneic Hematopoietic Stem Cell Transplantation
Authors: Maury Sébastien , Lemoine François M. , Hicheri Yosr , Rosenzwajg Michelle , Badoual Cécile , Cheraï Mustapha , Beaumont Jean-Louis , Azar Nabih , Dhedin Nathalie , Sirvent Anne , Buzyn Agnès , Rubio Marie-Thérèse , Vigouroux Stéphane , Montagne Olivier , Bories Dominique , Roudot-Thoraval Françoise , Vernant Jean-Paul , Cordonnier Catherine , Klatzmann David , Cohen José L.
Published: July 2010

Immunological effects of donor lymphocyte infusion for treatment of recurrent malignancy after allogeneic hematopoietic cell transplantation can be enhanced by depleting T regulatory cells in the infused cells and in the recipient.
Adapting to Aging and Metabolism
Authors: Bremer Andrew A.
Published: July 2010

Targeted disruption of the adaptor protein p66
shcA
improves longevity and ameliorates obesity-induced insulin resistance.
The association between radiographic knee osteoarthritis and knee symptoms, function and quality of life 10–15 years after anterior cruciate ligament reconstruction
Authors: Øiestad B E , Holm I , Engebretsen L , Risberg M A
Published: July 2010

Background

There are conflicting results in the literature regarding the association between radiographic knee osteoarthritis (OA) and symptoms and function in subjects with previous anterior cruciate ligament (ACL) reconstruction.

Aim

To investigate the associations between radiographic tibiofemoral knee OA and knee pain, symptoms, function and knee-related quality of life (QOL) 10–15 years after ACL reconstruction.

Study design

Cross-sectional study.

Material and methods

258 subjects were consecutively included at the time of ACL reconstruction and followed up prospectively. The authors included the Knee Injury and Osteoarthritis Outcome Score to evaluate knee pain, other symptoms (symptoms), activities of daily living and sport and recreation (Sport/Rec) and QOL. The subjects underwent standing radiographs 10–15 years after the ACL reconstruction. The radiographs were graded with the Kellgren and Lawrence (K&L) classification (grade 0–4).

Results

210 subjects (81%) consented to participate in the 10–15-year follow-up. Radiographic knee OA (K&L ≥grade 2) was detected in 71%, and 24% showed moderate or severe radiographic knee OA (K&L grades 3 and 4). No significant associations were detected between radiographic knee OA (K&L grade ≥2) and pain, function or QOL, respectively, but subjects with radiographic knee OA showed significantly increased symptoms. Severe radiographic knee OA (K&L grade 4) was significantly associated with more pain, symptoms, impaired Sport/Rec and reduced QOL.

Conclusion

Subjects with radiographic knee OA showed significantly more symptoms than those without OA, and subjects with severe radiographic knee OA had significantly more pain, impaired function and reduced quality of life than those without radiographic knee OA 10–15 years after ACL reconstruction.
Light regulation of endogenous salicylic acid levels in hypocotyls of Helianthus annuus seedlings
Authors: Kurepin Leonid V. , Walton Linda J. , Reid David M. , Chinnappa C. C.
Published: July 2010

Plants growing in canopy shade typically exhibit increased stem elongation and reduced leaf growth. This is as a result of direct interactions between plant photoreceptors sensing the change (reduction) in the ratio of red to far-red (R/FR) light and photosynthetically active radiation (PAR) and plant hormones, and regulating these morphological traits. The effect of the varying light conditions found in shade on endogenous salicylic acid (SA) content was tested, and the possible role of SA in shade avoidance by sunflower ( Helianthus annuus L.) hypocotyls was examined. A logarithmic increase in PAR irradiance levels increased endogenous SA levels roughly 10-fold. Separation of individual light wavelengths (R, FR, and blue) constituting the PAR irradiance of sunlight, established that only FR light had significant and positive effects on endogenous SA levels. Further, a low R/FR ratio significantly increased the endogenous SA content in hypocotyls compared with normal and high R/FR ratios. Uncoupling the effect of R/FR ratio and PAR irradiance on endogenous SA content demonstrated that PAR irradiance is a much stronger signal than FR light-enrichment. Thus, while a low R/FR ratio increases the SA content in sunflower hypocotyls, low PAR, the other component of canopy shade, decreases the SA content much more effectively than low R/FR ratio increases it. Therefore, it appears that SA probably has no direct role in shade avoidance effects.
Endoconidioma populifrom aspen and alder: phylogeny, and variations in cleistopycnidial morphology and their ecological implications
Authors: Tsuneda A. , Hambleton S. , Currah R. S.
Published: July 2010

Cleistopycnidial ontogeny and sequences of nuclear internal transcribed spacers (ITS) and large subunits (LSU) were compared for five strains of Endoconidioma populi Tsuneda et al.: three from trembling aspen and two from alder. The cleistopycnidia of two of the aspen strains, including the type strain, were subglobose to flask-shaped (mostly 35–100 µm × 30–60 µm), and consisted solely of meristematic cells with thick cell walls that were heavily impregnated with melanin granules. Peridial cells were not visibly differentiated from locular cells and were also capable of forming endoconidia. Endoconidia were released from one to several sites of the cleistopycnidium by the dissolution of peridial cell wall. The alder strains shared these characteristics, except that their cleistopycnidia released both endoconidia and conidiogenous cells. Unlike those four strains, cleistopycnidia of the third aspen strain were cylindrical, often exceeding 500 µm in length, branched, and possessed a peridium of textura angularis that developed from short, determinate hyphae. Conidiogenous cells contained abundant lipid bodies that were not mobilized until the onset of endoconidiogenesis. The peridium at the basal area was prone to breakage by external forces, indicating that the individual cleistopycnidium, as a whole, functions as a dispersal unit. A small number of ITS nucleotide differences among strains corresponded to their observed morphological differences and host association. Phylogenetic analyses suggested a close relationship of E. populi with Hormonema carpetanum Bills, Peláez & Ruibal, and Coniozyma leucospermi (Crous & Denman) Crous.
Single nucleotide polymorphisms in chum salmon (Oncorhynchus keta) mitochondrial DNA derived from restriction site haplotype information
Authors: Garvin M. R. , Saitoh K. , Churikov D. Y. , Brykov V. A. , Gharrett A. J.
Published: July 2010

Single nucleotide polymorphisms (SNPs) are useful genetic markers for the management and conservation of commercially important species such as salmon. Informative markers can be derived from data obtained for other purposes. We used restriction endonuclease data from earlier work to identify potentially useful restriction sites in chum salmon ( Oncorhynchus keta ). With the aid of a newly generated complete mitochondrial DNA sequence (accession number AP010773), we identified the SNP responsible for each restriction site variant, designed rapid genotyping assays, and surveyed the SNPs in more than 400 individuals. The restriction site analysis and the SNP genotyping assays were almost perfectly concordant. Some reasons for the non-concordance were identified and discussed.
Development of unigene-derived SSR markers in cowpea (Vigna unguiculata) and their transferability to otherVignaspecies
Authors: Gupta S. K. , Gopalakrishna T.
Published: July 2010

Unigene sequences available in public databases provide a cost-effective and valuable source for the development of molecular markers. In this study, the identification and development of unigene-based SSR markers in cowpea ( Vigna unguiculata (L.) Walp.) is presented. A total of 1071 SSRs were identified in 15 740 cowpea unigene sequences downloaded from the National Center for Biotechnology Information. The most frequent SSR motifs present in the unigenes were trinucleotides (59.7%), followed by dinucleotides (34.8%), pentanucleotides (4%), and tetranucleotides (1.5%). The copy number varied from 6 to 33 for dinucleotide, 5 to 29 for trinucleotide, 5 to 7 for tetranucleotide, and 4 to 6 for pentanucleotide repeats. Primer pairs were successfully designed for 803 SSR motifs and 102 SSR markers were finally characterized and validated. Putative function was assigned to 64.7% of the unigene SSR markers based on significant homology to reported proteins. About 31.7% of the SSRs were present in coding sequences and 68.3% in untranslated regions of the genes. About 87% of the SSRs located in the coding sequences were trinucleotide repeats. Allelic variation at 32 SSR loci produced 98 alleles in 20 cowpea genotypes. The polymorphic information content for the SSR markers varied from 0.10 to 0.83 with an average of 0.53. These unigene SSR markers showed a high rate of transferability (88%) across other Vigna species, thereby expanding their utility. Alignment of unigene sequences with soybean genomic sequences revealed the presence of introns in amplified products of some of the SSR markers. This study presents the distribution of SSRs in the expressed portion of the cowpea genome and is the first report of the development of functional unigene-based SSR markers in cowpea. These SSR markers would play an important role in molecular mapping, comparative genomics, and marker-assisted selection strategies in cowpea and other Vigna species.
Analysis of run-up of granular avalanches against steep, adverse slopes and protective barriers
Authors: Mancarella Davide , Hungr Oldrich
Published: July 2010

The purpose of this study was to determine whether run-up of rapid landslides or avalanches against protective dykes or walls placed perpendicular to the path can be predicted using a dynamic model based on shallow-flow assumptions. A series of laboratory experiments were carried out involving rapid flow of dry sand in a flume, arrested by a steep adverse slope. The barrier slope was varied and included a perpendicular wall. A curved transition of varying radius separated the path from the barrier. The dynamic internal and basal friction angles of the sand were determined by independent testing. The results were analysed using a Savage–Hutter type model. A shock wave was observed as the flow approached the barrier toe and the model had to be improved by an original velocity-smoothing algorithm to prevent numerical instability. The new model is capable of simulating the entire process of run-up of the leading edge against the barrier face, deposition of the sand behind the barrier, and backward migration of the shock wave. Comparisons between experiment and analysis results are presented. The model tends to overpredict the vertical run-up in cases where the barrier slope is steep. The results of traditional run-up formulas are also compared.
Statistical damage model with strain softening and hardening for rocks under the influence of voids and volume changes
Authors: Cao Wen-Gui , Zhao Heng , Li Xiang , Zhang Yong-Jie
Published: July 2010

With regards to the composition of natural rocks including voids or pores, deformation behavior is strongly affected by variation in porosity. By using a statistical damage-based approach, the characteristics of strain softening and hardening under the influence of voids and volume changes are investigated in the present paper. Suppose that a rock consists of three parts: voids, a damaged part, and an undamaged part. The effects of voids and volume changes on rock behavior are first analyzed through determination of the porosity and an associated damage model is then developed. Later, a statistical evolution equation describing the influence of the damage threshold on the propagation condition of rock damage is formulated based on measurement of the mesoscopic element strength. A statistical damage constitutive model reflecting strain softening and hardening behavior for rocks loaded in conventional triaxial compression is further developed and a corresponding method for determining the model parameters is also provided. Theoretical results of this proposed model are then compared with those observed experimentally. Finally, several aspects of the present constitutive model, which affect the relevant behavior of rocks, are particularly discussed.
Influence of toe restraint on reinforced soil segmental walls
Authors: Huang Bingquan , Bathurst Richard J. , Hatami Kianoosh , Allen Tony M.
Published: July 2010

A verified fast Lagrangian analysis of continua (FLAC) numerical model is used to investigate the influence of horizontal toe stiffness on the performance of reinforced soil segmental retaining walls under working stress (operational) conditions. Results of full-scale shear testing of the interface between the bottom of a typical modular block and concrete or crushed stone levelling pads are used to back-calculate toe stiffness values. The results of numerical simulations demonstrate that toe resistance at the base of a reinforced soil segmental retaining wall can generate a significant portion of the resistance to horizontal earth loads in these systems. This partially explains why reinforcement loads under working stress conditions are typically overestimated using current limit equilibrium-based design methods. Other parameters investigated are wall height, interface shear stiffness between blocks, wall facing batter, reinforcement stiffness, and reinforcement spacing. Computed reinforcement loads are compared with predicted loads using the empirical-based K-stiffness method. The K-stiffness method predictions are shown to better capture the qualitative trends in numerical results and be quantitatively more accurate compared with the AASHTO simplified method.
Protection of epithelial cells from Salmonella enterica serovar Enteritidis invasion by antibodies against the SPI-1 type III secretion system
Authors: Desin Taseen S. , Mickael Claudia S. , Lam Po-King S. , Potter Andrew A. , Köster Wolfgang
Published: July 2010

Salmonella enterica serovar Enteritidis (Salmonella Enteritidis) is one of the major causes of bacterial food-borne illness in humans. During the course of infection, Salmonella Enteritidis uses 2 type III secretion systems (T3SS), one of which is encoded on Salmonella pathogenicity island 1 (SPI-1). SPI-1 plays a major role in the invasion process. In the present study, we evaluated the effect of sera against the SPI-1 T3SS components on invasion in vitro using polarized human intestinal epithelial cells (Caco-2). Antisera to SipD protected Caco-2 cells against entry of wild-type Salmonella Enteritidis. On the other hand, sera against InvG, PrgI, SipA, SipC, SopB, SopE, and SopE2 did not affect Salmonella Enteritidis entry. To illustrate the specificity of anti-SipD mediated inhibition, SipD-specific antibodies were depleted from the serum. Antiserum depleted of SipD-specific antibodies lost its capacity to inhibit Salmonella Enteritidis entry. Thus, we demonstrate for the first time that antibodies against the SPI-1 needle tip protein (SipD) inhibit Salmonella Enteritidis invasion and that the SipD protein may be an important target in blocking SPI-1 mediated virulence of Salmonella Enteritidis.
Antimycobacterial screening of traditional medicinal plants using the microplate resazurin assay
Authors: Webster Duncan , Lee Timothy D.G. , Moore Jill , Manning Tracy , Kunimoto Dennis , LeBlanc Darren , Johnson John A. , Gray Christopher A.
Published: July 2010

Multidrug-resistant Mycobacterium tuberculosis strains have rapidly become a global health concern. North American First Nations communities have used traditional medicines for generations to treat many pulmonary infections. In this study, we evaluated the antimycobacterial activity of 5 medicinal plants traditionally used as general therapeutics for pulmonary illnesses and specifically as treatments for tuberculosis. Aqueous extracts of Aralia nudicaulis , Symplocarpus foetidus , Heracleum maximum , Juniperus communis, and Acorus calamus were screened for antimycobacterial activity against Bacillus Calmette–Guérin, Mycobacterium avium, and M. tuberculosis H37Ra using the colorimetric microplate resazurin assay. Extracts of Acorus calamus and H. maximum root demonstrated significant antimycobacterial activity comparable to that of the rifampin control (2 µg/mL). Evaluation of the cytotoxicity of these 2 extracts using the MTT assay also showed that the extracts were less toxic to 3 human cell lines than was the DMSO positive control. This study demonstrates that aqueous extracts of the roots of H. maximum and Acorus calamus possess strong in vitro antimycobacterial activity, validates traditional knowledge, and provides potential for the development of urgently needed novel antituberculous therapeutics.
ET-1 plasma levels and ocular blood flow in retinitis pigmentosaThis article is one of a selection of papers published in the two-part special issue entitled 20 Years of Endothelin Research.
Authors: Cellini Mauro , Strobbe Ernesto , Gizzi Corrado , Campos Emilio C.
Published: July 2010

Retinitis pigmentosa (RP) is an inherited retinal disorder clinically characterized by a pale, waxy optic nerve head, attenuated retinal blood vessels, and bone spicule pigment in the retina. Hemodynamic studies have demonstrated that RP is associated with a reduction in the retinal and choroidal blood flow. Retinal hemodynamic impairment is also present in early stages of RP, and various hypotheses have been advanced as to the cause. The authors studied 20 patients, 12 males and 8 females, aged 26–42 years (mean 35.1 years) and affected by simplex RP. The patients had a visual acuity of 0.9 ± 0.1, visual field mean defect of –6.52 ± 3.58 dB, and b-wave electroretinogram amplitude of 260.08 ± 8.24 µV. An increase in plasma levels of endothelin-1 (ET-1) was found: 1.910 ± 0.317 pg/mL versus 1.180 ± 0.210 pg/mL in non-RP controls (p < 0.02). Moreover both an ocular and systemic vascular impairment was detected by means of color Doppler imaging and laser Doppler flowmetry performed during a cold pressor test. We found a correlation between the increase of ET-1 plasma levels in RP and the decrease of peak systolic velocity in the ophthalmic artery (p < 0.03) and in the posterior ciliary arteries (p < 0.006). It is thought that an increase of ET-1 and retinal oxygen levels in RP could lead to vasoconstriction and a decrease of the retinal blood flow, worsening the abiotrophic process.
Remarkably long-lasting tachyphylaxis of pain responses to ET-1: evidence against central nervous system involvementThis article is one of a selection of papers published in the two-part special issue entitled 20 Years of Endothelin Research.
Authors: Khodorova Alla , Strichartz Gary R.
Published: July 2010

A profound tachyphylaxis of the acute nocifensive flinching (pain) response to subcutaneous injection of endothelin-1 (ET-1) into the hind paw footpad is shown by the reduced response to a second injection. Flinching from the second injection was 20% ± 5%, 57% ± 18%, 79% ± 35%, and 100% ± 17% of that from the first injection (both 200 µmol/L, 2 nmol) at respective intervals of 24, 30, 48, and 72 h. Inhibition of afferent impulses by local anesthesia of the sciatic nerve, reducing initial flinching to 6%–13% of control, did not affect the tachyphylaxis for the second injection at 24 h. There was no cross-desensitization between formalin and ET-1 injected sequentially into the same paw. Suppression of descending inhibitory effects from endogenous opiates by naloxone (5–8 mg/kg, i.p.), given 30 min before the second ET-1 injection, did not prevent tachyphylaxis. Diffuse effects caused by an initial subcutaneous ET-1 injection into the tail or forepaw resulted in sensitization of the response to ET-1 in the hind paw, rather than tachyphylaxis. In contrast, selective inhibition of local ETAreceptors during the initial administration of ET-1, by the antagonist BQ-123 (3.2 mmol/L), reduced tachyphylaxis of nocifensive flinching. Therefore, prolonged pain tachyphylaxis is not due to reduced responsiveness of the CNS, but rather depends on the functional sensitivity or availability of peripheral ETAreceptors.
STUDY ON DEEP TRAP STATES IN POLYMERS BY PHOTO-STIMULATED DISCHARGE BASED ON THE OPO LASER
Authors: HE LI-JUAN , DAI LI , YANG CHUN , TIAN FU-QIANG , ZHAO LEI , CAO JING-LEI , WANG XUAN , LEI QING-QUAN
Published: July 2010

A photo-stimulated discharge (PSD) method is more effective than thermal methods to characterize the deep space charge traps in dielectric materials. In this paper, a new PSD measuring system was first built up based on the optical parametric oscillator laser. The laser can generate continuously tunable wavelengths whose range are 210–420 nm and with average output pulse energy 2.3 mJ. The system overcomes the shortcoming of weak output energy in past experiments, especially in the range of ultraviolet band. The PSD current spectra of PET were measured by this system. The results show that the energy level of charge traps in the PET film is mainly distributed in 4.08~5.18 eV, and the trap density maximum is at 4.22 eV. These data can provide the experimental basis for further research and improvement on electrical properties of materials.
STUDY ON THE NONLINEAR VIBRATION OF SWCNTs WITH INITIAL AXIAL STRESS BASED ON THE BIFURCATION THEORY OF DYNAMICAL SYSTEMS
Authors: YAN YAN , WANG WENQUAN , ZHANG LIXIANG
Published: July 2010

The nonlinear dynamical behaviors of single-walled carbon nanotubes (SWCNTs) with the initial axial stress are investigated based on Donnell's cylindrical shell model. By using the bifurcation theory of dynamical systems on a vibration equation of SWCNTs, the existence of centers, saddles, families of periodic orbits, homoclinic orbits and/or heteroclinic orbits is shown. Under different initial conditions, various sufficient conditions to guarantee the existence of the above solutions are given and the dynamical behaviors of SWCNTs are well-known.
PREPARATION AND SPECTROSCOPIC PROPERTIES OF Yb:YAG GLASS-CERAMICS
Authors: LAI FEI , ZHANG YUE-PIN , XIA HAI-PING , ZHANG XIN-MING , WANG JIN-HAO
Published: July 2010

Yb 3+-doped 32 CaO -12 Y 2 O 3-24 Al 2 O 3-31 SiO 2-1 Yb 2 O 3 glasses were prepared by melting method, and then annealed at 950°C, 1050°C and 1100°C, respectively. We analyzed the crystallographic structures of the glasses annealed at different temperatures by XRD, and observed the glass annealed at 1050°C by TEM. The spectroscopic properties of glass before and after annealing were also investigated. Results show that the glasses annealed at 1050°C are YAG glass-ceramics with no impurity crystalline phase. Variances in the spectroscopic properties before and after heat treatment indicate that Yb 3+ ions were preferentially partitioned into the YAG crystal phase, and the transparent Yb : YAG glass-ceramics were obtained.
MAGNETIC BEHAVIOR OF FUNCTIONALLY COATED SUPER-PARAMAGNETIC Ni0.5Cu0.5Fe2O4-POLYPYRROLE NANO-COMPOSITES
Authors: PRASAD ARUN S. , DOLIA S. N. , REDDY V. R. , PREDEEP P.
Published: July 2010

This article has been retracted. A statement of retraction is published in Mod. Phys. Lett. B Volume 28, Issue 26 (2014) http://dx.doi.org/10.1142/S0217984914930014
RAMAN STUDY OF xMeO · (100-x)[P2O5 · CaO](MeO=Fe2O3, V2O5 OR (Fe2O3 · V2O5)) GLASS SYSTEMS
Authors: ANDRONACHE CONSTANTIN
Published: July 2010

Glasses from x MeO · (100-x)[ P 2 O 5 · CaO ], ( MeO = Fe 2 O 3, V 2 O 5 or ( Fe 2 O 3 · V 2 O 5)) were prepared and investigated using Raman scattering spectroscopy, over compositional range x=0–50% mol. The influence of Fe 2 O 3, V 2 O 5 or ( Fe 2 O 3· V 2 O 5) content on the structure of P 2 O 5· CaO glass matrix was followed. The addition of Fe 2 O 3, V 2 O 5 or ( Fe 2 O 3· V 2 O 5) determines the modification of the structure of the studied glasses. The Raman spectra of x Fe 2 O 3(100-x)[ P 2 O 5· CaO ] do not present any absorption bands characteristic to Fe 2 O 3 but its evolution is dependent on the iron content. The Raman spectra of x V 2 O 5·(100-x)[ P 2 O 5· CaO ] present, besides the bands specific for the matrix, some bands assigned to characteristic vibrations of V – O bonds which are evidenced only for high content of V 2 O 5. The evolution of the spectra is dependent on V 2 O 5 content. The Raman spectra of x( Fe 2 O 3· V 2 O 5)·(100-x)[ P 2 O 5· CaO ] system showed that phosphate units are the main structural units of the glass system, iron and vanadium ions are located in the network. The increasing of iron and vanadium content indicate a gradual decrease in the number of bridging oxygen ions and an increase in the number of non-bridging oxygen ions.
Glucagon receptor antagonist-mediated improvements in glycemic control are dependent on functional pancreatic GLP-1 receptor
Authors: Gu Wei , Winters Katherine A. , Motani Alykhan S. , Komorowski Renée , Zhang Ying , Liu Qingxiang , Wu Xiaosu , Rulifson Ingrid C. , Sivits Glenn , Graham Melissa , Yan Hai , Wang Paul , Moore Steve , Meng Tina , Lindberg Richard A. , Véniant Murielle M.
Published: July 2010

Antagonism of the glucagon receptor (GCGR) is associated with increased circulating levels of glucagon-like peptide-1 (GLP-1). To investigate the contribution of GLP-1 to the antidiabetic actions of GCGR antagonism, we administered an anti-GCGR monoclonal antibody (mAb B) to wild-type mice and GLP-1 receptor knockout (GLP-1R KO) mice. Treatment of wild-type mice with mAb B lowered fasting blood glucose, improved glucose tolerance, and enhanced glucose-stimulated insulin secretion during an intraperitoneal glucose tolerance test (ipGTT). In contrast, treatment of GLP-1R KO mice with mAb B had little efficacy during an ipGTT. Furthermore, pretreatment with the GLP-1R antagonist exendin-(9–39) diminished the antihyperglycemic effects of mAb B in wild-type mice. To determine the mechanism whereby mAb B improves glucose tolerance, we generated a monoclonal antibody that specifically antagonizes the human GLP-1R. Using a human islet transplanted mouse model, we demonstrated that pancreatic islet GLP-1R signaling is required for the full efficacy of the GCGR antagonist. To identify the source of the elevated GLP-1 observed in GCGR mAb-treated mice, we measured active GLP-1 content in pancreas and intestine from db/db mice treated with anti-GCGR mAb for 8 wk. Elevated GLP-1 in GCGR mAb-treated mice was predominantly derived from increased pancreatic GLP-1 synthesis and processing. All together, these data show that pancreatic GLP-1 is a significant contributor to the glucose-lowering effects observed in response to GCGR antagonist treatment.
N-acetylhistidine, a novel osmolyte in the lens of Atlantic salmon (Salmo salar L.)
Authors: Rhodes Jeremy D. , Breck Olav , Waagbo Rune , Bjerkas Ellen , Sanderson Julie
Published: July 2010

Volume homeostasis is essential for the preservation of lens transparency and this is of particular significance to anadromous fish species where migration from freshwater to seawater presents severe osmotic challenges. In Atlantic salmon ( Salmo salar L.), aqueous humor (AH) osmolality is greater in fish acclimated to seawater compared with young freshwater fish, and levels of lens N-acetylhistidine (NAH) are much higher in seawater fish. Here we investigate NAH as an osmolyte in the lenses of salmon receiving diets either with or without histidine supplementation. In the histidine-supplemented diet (HD) histidine content was 14.2 g/kg, and in the control diet (CD) histidine content was 8.9 g/kg. A transient increase in AH osmolality of 20 mmol/kg was observed in fish transferred from freshwater to seawater. In a lens culture model, temporary decreases in volume and transparency were observed when lenses were exposed to hyperosmotic conditions. A positive linear relationship between extracellular osmolality and lens NAH content was also observed, whereas there was no change in lens histidine content. Hypoosmotic exposure stimulated [14C]-histidine efflux by 9.2- and 2.6-fold in CD and HD lenses, respectively. NAH efflux, measured by HPLC, was stimulated by hypoosmotic exposure to a much greater extent in HD lenses. In vivo, lens NAH increased in response to elevated AH osmolality in HD but not CD fish. In conclusion, NAH has an important and novel role as a compatible osmolyte in salmon lens. Furthermore, it is the major osmolyte that balances increases in AH osmolality when fish move from freshwater to seawater. A deficiency in NAH would lead to a dysfunction of the normal osmoregulatory processes in the lens, and we propose that this would contribute to cataract formation in fish deficient in histidine.
Renal autoregulation and passive pressure-flow relationships in diabetes and hypertension
Authors: Hill J. V. , Findon G. , Appelhoff R. J. , Endre Z. H.
Published: July 2010

We investigated renal hemodynamics in isolated, perfused kidneys from rat models of diabetes and hypertension. Autoregulation and passive vascular responses were measured using stepped pressure ramps in the presence of angiotensin II (pEC50) or papaverine (0.1 mM), respectively. Male diabetic heterozygote m(Ren2)27 rats were compared with three male control groups: nondiabetic, normotensive Sprague-Dawley (SD) rats; nondiabetic, hypertensive heterozygote m(Ren2)27 rats; and diabetic, normotensive SD rats. Kidney function (proteinuria, creatinine clearance) was monitored before induction and at monthly intervals. Vascular function was measured in vitro in rats of induction age (6–8 wk) and at 2 and 4 mo postinduction. Renal flow correlated with age, but not diabetes or the Ren2 gene. Kidney weight-specific and body weight-specific renal flow differed between diabetic and nondiabetic rats because diabetic rats had higher kidney but lower body weights. Kidneys from all groups showed effective autoregulation in the presence of angiotensin II. The autoregulatory pressure threshold of m(Ren2)27 rats was higher, and the autoregulation pressure range was wider, compared with SD rats. When vascular smooth muscle activity was blocked with papaverine, pressure-flow responses differed between groups and with time. The m(Ren2)27 rat groups showed higher renal vascular resistance at lower pressures, suggesting greater vascular stiffness. In contrast, diabetic SD rat kidneys demonstrated reduced vessel stiffness. Flow was impaired in diabetic m(Ren2)27 rats at 4 mo, and this correlated with a decline in creatinine clearance. The results suggest that the characteristic late decline in renal filtration function in diabetes- and hypertension-related renal disease follows changes in renal vascular compliance.
Female Sprague Dawley Rats Show Impaired Spatial Memory in the 8-Arm Radial Maze under Dim Blue and Red Light
Authors: Pirchl Michael , Kemmler Georg , Humpel Christian
Published: July 2010

Light intensity and wavelength strongly influence mood and cognition in humans and rodent animal models. The aim of the present study was to explore if dim white (7.6–17.7 lux) , blue (1.3–2.3 lux), and red light (0.8–1.4 lux) affect spatial memory of male and female Sprague Dawley rats in the 8-arm radial maze. Our data show that spatial memory significantly improved within 5 daily learning sessions (each 5 trials) under dim white light, which was not different between male and female rats. However, dim blue and red light significantly reduced spatial learning of female rats in the 8-arm radial maze in the last training session (session 5). In conclusion, we suggest that female Sprague Dawley rats show reduced learning under blue and red light.
Numerical Modeling of the Severe Cold Weather Event over Central Europe (January 2006)
Authors: Hari Prasad D. , Wibig Joanna , Rzepa Marcin
Published: July 2010

Cold waves commonly occur in higher latitudes under prevailing high pressure systems especially during winter season which cause serious economical loss and cold related death. Accurate prediction of such severe weather events is important for decision making by administrators and for mitigation planning. An Advanced high resolution Weather Research and Forecasting mesoscale model is used to simulate a severe cold wave event occurred during January 2006 over Europe. The model is integrated for 31 days starting from 00UTC of 1 January 2006 with 30 km horizontal resolution. Comparison of the model derived area averaged daily mean temperatures at 2m height from different zones over the central Europe with observations indicates that the model is able to simulate the occurrence of the cold wave with the observed time lag of 1 to 3days but with lesser intensity. The temperature, winds, surface pressure and the geopential heights at 500 hPa reveal that the cold wave development associates with the southward progression of a high pressure system and cold air advection. The results have good agreement with the analysis fields indicates that the model has the ability to reproduce the time evolution of the cold wave event.
Size-Related Differences in the Thermoregulatory Habits of Free-Ranging Komodo Dragons
Authors: Harlow Henry J. , Purwandana Deni , Jessop Tim S. , Phillips John A.
Published: July 2010

Thermoregulatory processes were compared among three-size groups of free-ranging Komodo dragons (Varanus komodoensis) comprising small (5–20 kg), medium (20–40 gm) and large (40–70 kg) lizards. While all size groups maintained a similar preferred body temperature of≈35∘C, they achieved this end point differently. Small dragons appeared to engage in sun shuttling behavior more vigorously than large dragons as represented by their greater frequency of daily ambient temperature and light intensity changes as well as a greater activity and overall exposure to the sun. Large dragons were more sedentary and sun shuttled less. Further, they appear to rely to a greater extent on microhabitat selection and employed mouth gaping evaporative cooling to maintain their preferred operational temperature and prevent overheating. A potential ecological consequence of size-specific thermoregulatory habits for dragons is separation of foraging areas. In part, differences in thermoregulation could contribute to inducing shifts in predatory strategies from active foraging in small dragons to more sedentary sit-and-wait ambush predators in adults.
A Chemosensitization Screen Identifies TP53RK, a Kinase that Restrains Apoptosis after Mitotic Stress
Authors: Peterson David , Lee James , Lei Xingye C. , Forrest William F. , Davis David P. , Jackson Peter K. , Belmont Lisa D.
Published: July 2010

Taxanes are very effective at causing mitotic arrest; however, there is variability among cancer cells in the apoptotic response to mitotic arrest. The variability in clinical efficacy of taxane-based therapy is likely a reflection of this variability in apoptotic response, thus elucidation of the molecular mechanism of the apoptotic response to mitotic stress could lead to improved clinical strategies. To identify genes whose expression influences the rate and extent of apoptosis after mitotic arrest, we screened a kinase-enriched small interfering RNA library for effects on caspase activation in response to maximally effective doses of paclitaxel, a PLK1 inhibitor, or cisplatin. Small interfering RNA oligonucleotides directed against an atypical protein kinase, TP53RK, caused the greatest increase in caspase-3/7 activation in response to antimitotic agents. Time-lapse microscopy revealed that cells entered mitosis with normal kinetics, but died after entry into mitosis in the presence of paclitaxel more rapidly when TP53RK was depleted. Because expression levels of TP53RK vary in cancers, TP53RK levels could provide a molecular marker to predict response to antimitotic agents. TP53RK inhibition may also sensitize cancers to taxanes. Cancer Res; 70(15); 6325–35. ©2010 AACR.