bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of fatigue model results for rough surface elastohydrodynamic lubrication
Authors: Qiao H , Evans H P , Snidle R W 
Published: May 2008

The paper compares the results of applying different fatigue failure models to surfaces that experience elastohydrodynamic lubrication (EHL) and have surface roughness features which are large compared with the equivalent smooth surface film thickness. The surface profiles used for the comparisons reported are taken from test gear surfaces used in an FZG gear test. The surface has a roughness of 0.31 μm Ra, with peak to valley dimensions of the order 1.5 μm. The tips of the asperities have been modified by running-in during the gear test. A transient EHL analysis was carried out using contacting components having this profile for a number of sliding speeds and nominal viscosity values. From these analyses, time-dependent pressure and shear stress distributions at the contacting surfaces were calculated. The resulting subsurface stress field was obtained relative to axes fixed in the moving surfaces using an elastic analysis so as to give the stress history at each point in a representative test section of the contacting component. A number of multi-axial fatigue criteria based on a critical plane approach were applied to the test section and the results compared. In addition, a varying amplitude multi-axial fatigue theory based on shear strain cycles was also applied to the section. The cycle counts were obtained using the rainflow counting method and the accumulated damage in a single pass through the contact area was calculated. In comparing the results obtained, the various fatigue models were found to identify the same asperity features as being those most prone to fatigue.
Influence of slide-to-roll ratio on tribofilm generation
Authors: Meheux M , Minfray C , Ville F , Mogne T Le , Lubrecht A A , Martin J M , Lieurade H P 
Published: May 2008

Rolling contact fatigue has become a surface initiated problem. This phenomenon is due to the initiation and propagation of cracks from the surface to the volume of mechanical pieces. A great amount of research has been done since the 1970s to understand its origin, but many aspects remain unclear. Many authors found that the lubricant composition and especially certain additives can either improve or reduce fatigue life, depending on the operating conditions. It is now admitted that additives form a tribofilm in the rubbing track, especially under pure sliding conditions, but no direct relation to rolling contact fatigue has been drawn to this moment. The knowledge of the reaction pathways of lubricant additives under various sliding conditions as well as the tribofilm properties and morphology has become an important issue. In this work, the mini traction machine has been used to study friction under different sliding conditions of a pure mineral base oil and a formulated oil containing five selected additives. The results suggest that friction is likely to mimic tribofilm formation. The slide-to-roll ratio influences the rate of direct asperity contacts and hence tribofilm growth.
A study of contact temperature and tribological behaviour of magnetized sliding brass—steel couple in different gas environments
Authors: Amirat M , Zaïdi H , Frêne J 
Published: May 2008

The wear tests of the sliding magnetized brass—steel couple are investigated on a pin—disc configuration under three various gas environments: in ambient air, under oxygen at 105 Pa, and in vacuum at 1.5 × 10−6 torr. The tribological behaviour of the couple strongly depends on the environment gas and a little effect of the magnetic field intensity. The results obtained show that the magnetic field decreases the wear rate and the friction coefficient in both air and oxygen atmosphere, respectively. However, in vacuum, the magnetic field has a negligible effect. The wear mode follows a transition from abrasive wear to adhesive wear after some cycles at the beginning of sliding contact. The temperature increment is very large in vacuum and it is almost stationary in both ambient air and oxygen. On the other hand, the application of magnetic field induces a little increase in contact temperature of average value about 5–8 °C in each gas environment. The temperature rise is correlated directly to interface properties, namely the hardness, the real contact area, and the roughness of the steel counterface.
Tribo-corrosion analysis of wear and metal ion release interactions from metal-on-metal and ceramic-on-metal contacts for the application in artificial hip prostheses
Authors: Yan Y , Neville A , Dowson D , Williams S , Fisher J 
Published: May 2008

Osteolysis induced by polyethylene wear debris from metal-on-polyethylene total joint replacements is one of the major reasons for the renewed interest in metal-on-metal (MoM) bearings for total hip arthroplasty. However, long-term clinical performance is as yet unknown for the second generation MoM hip prostheses. The main concerns are the released metal ions and metallic wear debris from the artificial joints. It is well known that the metal ion release processes (corrosion) are electrochemical in nature. When two contacted components are in relative motion, wear can occur and it can accelerate corrosion. The role of corrosion in the generation of metallic wear debris is still not well understood. This paper addresses this point and makes a comparison of MoM and ceramic-on-metal (CoM) contacts. In this paper, tests were conducted on a pin-on-plate tester with an integrated electrochemical cell in 25 per cent bovine serum to determine the effects of pin rotation on the wear and metal ion release of two different combinations (metal pins with metal plates and metal pins with medical grade Alumina plates). The overall wear and released metallic ions were reduced with rotational movement of the pin in addition to the reciprocating action of the plate. For the CoM combination, a reduction of wear was associated with a more noble open circuit potential compared with the MoM combination.
Thin coatings with graded elastic properties
Authors: Dahm K L 
Published: May 2008

Thin W—Nb coatings were sputter co-deposited from pure targets on glass substrates with Nb contents from 14 to 70 at%. Pure W coatings (2.5 μm thick) were deposited on Ti-6Al-4V substrates with and without 0.5-μ m thick W—Nb interlayers to assess the influence of graded elastic properties on the adhesion of the W coatings. Two interlayer compositions were studied: 31 and 50 at% Nb. All of the W—Nb coatings were crystalline and solely body centre cubic. The plane strain elastic modulus ( E′ c) and hardness ( H c) of the coatings (as measured by nanoindentation) increased with increasing W content. E′ c increased from 223 ± 16 GPa at 70 at% Nb to 587±91 GPa for a pure W coating. Over the same composition range H c increased from 8.51±0.25 to 13.49±1.04 GPa. No delamination was observed for any of the coated Ti-6Al-4V samples after adhesion testing by Rockwell C (Rc) indentation or scratch testing (at loads up to 5.00 kg). Through-coating cracks were observed around the rims of the Rc indents and within the scratches (at loads of 1.00 kg and higher). In all cases, the density of these cracks increased in the following order: 50 at% Nb interlayer<31 at% Nb interlayer<no interlayer.
Viscosity measurement in thin lubricant films using shear ultrasonic reflection
Authors: Kasolang S , Dwyer-Joyce R S 
Published: May 2008

When a shear ultrasonic wave is incident on a solid and liquid boundary, the proportion that is reflected depends on the liquid viscosity. This is the basis for some instruments for on-line measurement of bulk liquid viscosity. In machine elements, the lubricant is usually present in a thin layer between two rubbing solid surfaces. The thin film has a different response to an ultrasonic shear wave than liquid in bulk. In this work, this response is investigated with the aim of measuring viscosity in situ in a lubricating film. The proportion of the wave reflected at a thin layer depends on the layer stiffness. A shear wave is reflected by the shear stiffness of the thin layer. For a thin viscous liquid layer, the stiffness is a complex quantity dependent on the viscosity, wave frequency, and film thickness. This stiffness is incorporated into a quasi-static spring model of ultrasonic reflection. In this way, the viscosity can be determined from shear-wave reflection if the oil-film thickness is known. The approach has been experimentally evaluated on some static oil film between Perspex plates. Predictions of the spring model gave good measurement up to layer thicknesses of around 15 μm. For thicker layers, the shear stiffness reduces to such an extent that almost all the wave is reflected and the difference associated with the layer response is hard to distinguish from background noise.
Lubricant/surface interactions under extreme pressure conditions: Corrosion inhibitor interacting extreme pressure/anti-wear additives on steel surface
Authors: Mistry K K , Neville A , Morina A , Webster M N 
Published: May 2008

Many mechanical systems operate under mixed-boundary lubricated conditions. Moreover, these mechanical systems have highly loaded non-conformal contact surfaces, therefore significantly influencing friction/wear performance and also inducing various modes of failures. Hence, it is important to optimize selection of the lubricant since it plays a crucial role in controlling friction and affecting durability by forming tribochemical film on top of contact surfaces. The aim of the present work is to investigate the influence of extreme pressure additives, anti-wear additives, and corrosion inhibitors interacting at a steel/steel lubricated contact under extreme conditions and characterize the additive/surface interactions by advanced surface analysis techniques. The tribological testing was carried out employing a ball-on-disc test rig (ASTM G99-05) to measure friction. The wear on the balls was observed on the optical microscope after completion of the tribotest. Energy dispersive X-ray analysis and X-ray photoelectron spectroscopy were used to access the chemistry on the surface. In this paper, synergistic effects and antagonistic effects in terms of tribological parameters (friction and wear) are discussed, and mechanisms of the interactions are explained by surface analysis. Implications for optimizing the system performance are discussed.
An Unusual Reaction of a Pyridinium Ylide with 1,1-Dicyanoethylene Derivatives
Authors: Yamada Shinji , Ohta Emiko 
Published: May 2008

Abstract
A reaction of pyridinium perfluorophenacylide generated from pyridinium salt 1 with 1,1-dicyanoethylene derivatives 2 produced unusual products 3, which have an ylide structure with a cyano group at the C2 and a cis-acrylonitrile moiety at the o-position of the perfluorophenyl group. A plausible mechanism involving intramolecular aromatic nucleophilic substitution and 1,3-migration of the cyano group is proposed for this reaction.
Self-Defense and the Mistaken Racist
Authors: Garvey Stephen P. 
Published: May 2008

How should the law of a liberal state respond when one person (D) kills another person (V), who is black, because D believes that V is about to kill him, but D would not have believed that V was about to kill him if V had been white? Should D be exonerated on grounds of self-defense? Some commentators argue that D's claim of self-defense should be rejected and that he should be convicted, either of murder or manslaughter, and punished accordingly.
I disagree. I argue that denying D's claim of self-defense would be at odds with the principle that an actor should be punished, not for possessing or choosing to possess racist or otherwise illiberal beliefs or desires, but only for choosing to cause (or risk causing) harm when the law does not permit him to make such a choice. Moreover, insofar as this principle can fairly be characterized as one to which a liberal state must adhere, then a liberal state should acknowledge D's claim of self-defense.
Self-Defense: Reasonable Beliefs or Reasonable Self-Control?
Authors: Simons Kenneth W. 
Published: May 2008

The reasonable person test is often employed in criminal law doctrine as a criterion of cognitive fault: Did the defendant unreasonably fail to appreciate a risk of harm, or unreasonably fail to recognize a legally relevant circumstance element (such as the nonconsent of the victim)? But it is sometimes applied more directly to conduct: Did the defendant depart sufficiently from a standard of reasonable care, e.g., in operating a motor vehicle, that he deserves punishment? A third version of the reasonable person criterion, which has received much less attention, asks what degree of control a reasonable person would have exercised. Many criminal acts occur in highly emotional, stressful, or emergency situations, situations in which it is often both unrealistic and unfair to expect the actor to formulate beliefs about all of the facts relevant to the legality or justifiability of his conduct. A "reasonable degree of self-control" criterion is sometimes the best criterion for embracing these contextual factors.
In self-defense, for example, it is conventional to ask whether the actor believes, and whether a reasonable person would believe, each of the following facts: (a) an aggressor was threatening him with harm, (b) that harm would be of a particular level of gravity, (c) his use of force in response would prevent that harm, (d) the level of responsive force he expects to employ would be of a similar level of gravity, (e) if the force was not used, the threatened harm would occur immediately, and (f ) no nonviolent or less forceful alternatives were available whereby the threat could be avoided. United States law typically requires an affirmative answer to each of these questions. Yet in many cases, an actor threatened with harm will actually have no beliefs at all about most of these matters. It would be unfair to deny a full defense to all such actors. At the same time, we should still hold such an actor to a normative standard of justifiable behavior. Specifically, this essay suggests that we reformulate the reasonableness criterion and require this type of actor to exercise a reasonable degree of selfcontrol in response to a threat of force.
Hypoxia Enhances Tumor Stemness by Increasing the Invasive and Tumorigenic Side Population Fraction
Authors: Das Bikul , Tsuchida Rika , Malkin David , Koren Gideon , Baruchel Sylvain , Yeger Herman 
Published: May 2008

Abstract
Although advances have been made in understanding the role of hypoxia in the stem cell niche, almost nothing is known about a potentially similar role of hypoxia in maintaining the tumor stem cell (TSC) niche. Here we show that a highly tumorigenic fraction of side population (SP) cells is localized in the hypoxic zones of solid tumors in vivo. We first identified a highly migratory, invasive, and tumorigenic fraction of post-hypoxic side population cells (SPm[hox] fraction) in a diverse group of solid tumor cell lines, including neuroblastoma, rhabdomyosarcoma, and small-cell lung carcinoma. To identify the SPm(hox) fraction, we used an “injured conditioned medium” derived from bone marrow stromal cells treated with hypoxia and oxidative stress. We found that a highly tumorigenic SP fraction migrates to the injured conditioned medium in a Boyden chamber. We show that as few as 100 SPm(hox) cells form rapidly growing tumors in vivo. In vitro exposure to hypoxia increases the SPm(hox) fraction significantly. Quantitative real-time polymerase chain reaction and immunofluorescence studies showed that SPm(hox) cells expressed Oct-4, a “stemness” gene having a potential role in TSC maintenance. In nude mice xenografts, SPm(hox) cells were localized to the hypoxic zones, as demonstrated after quantum dot labeling. These results suggest that a highly tumorigenic SP fraction migrates to the area of hypoxia; this migration is similar to the migration of normal bone marrow SP fraction to the area of injury/hypoxia. Furthermore, the hypoxic microenvironment may serve as a niche for the highly tumorigenic fraction of SP cells.
Disclosure of potential conflicts of interest is found at the end of this article.
Concise Review: Pax6 Transcription Factor Contributes to both Embryonic and Adult Neurogenesis as a Multifunctional Regulator
Authors: Osumi Noriko , Shinohara Hiroshi , Numayama-Tsuruta Keiko , Maekawa Motoko 
Published: May 2008

Abstract
Pax6 is a highly conserved transcription factor among vertebrates and is important in various developmental processes in the central nervous system (CNS), including patterning of the neural tube, migration of neurons, and formation of neural circuits. In this review, we focus on the role of Pax6 in embryonic and postnatal neurogenesis, namely, production of new neurons from neural stem/progenitor cells, because Pax6 is intensely expressed in these cells from the initial stage of CNS development and in neurogenic niches (the subgranular zone of the hippocampal dentate gyrus and the subventricular zone of the lateral ventricle) throughout life. Pax6 is a multifunctional player regulating proliferation and differentiation through the control of expression of different downstream molecules in a highly context-dependent manner.
Disclosure of potential conflicts of interest is found at the end of this article.
The Essence of Res(ex)pectability
Authors: Reid-Brinkley Shanara R. 
Published: May 2008

Abstract
In the late fall of 2004, following the media spectacle created by Spelman College's protest of the misogyny and sexism in the music and videos of rapper Nelly, Essence, a popular black women's magazine, began a campaign to raise awareness. Arguing that a more public discussion by black women of the issue of misogyny in rap's portrayal of black women is long overdue, the magazine published a year-long series of articles as part of its “Take Back the Music” campaign. More interesting than the series of articles produced by the magazine is the overwhelming response generated on its internet-based scribble boards, which offered their readers the opportunity to participate in a communal dialogue. Arguing that the scribble boards became a black women's temporary “safe space,” this essay interrogates the manner in which black women construct subject positions around the performance of race, class, and gender as a means to resist dominant representations of black women, while simultaneously engaging in disciplinary practices that constrain black femininity.
“Roll It Gal”
Authors: Springer Jennifer Thorington 
Published: May 2008

Abstract
“‘Roll It Gal’: Alison Hinds, Female Empowerment, and Calypso” examines the ways in which Caribbean women's bodies, namely those of black women, have been overly sexualized in calypsos. More importantly, this article examines how Hinds (re)claims calypso and its dance forms to empower women cross-culturally. She subverts traditional representations of womanhood in her songs and performances, thereby expanding existing definitions of womanhood. Hinds addresses women's ambivalent relationships with the performance and celebration of Caribbean culture through dance as she recovers/reinvents the female body. Hinds's ability to demand respect for her “wining” skills is also discussed. She validates the “wuk up” as an art form intrinsic to Caribbean culture, and openly challenges colonial ideologies that conceptualize “wukking up” as inappropriate or disrespectful. Simultaneously, in her claim of being “de ruffest gal winer” that no man/woman can test, Hinds's own dance performance becomes a subversive text and not merely dance as aesthetic pleasure.
Procedure guidelines for MIBG-scintigraphy in children
Authors: Schmidt M. , Hero B. , Pfluger T. , Hahn K. , Franzius C. 
Published: May 2008

SummaryThe German translation of the EANM guideline for MIBG scintigraphy in children (Olivier P et al. EJNM MI 2003; 30: B45–B50; Hahn K. Der Nuklearmediziner 2002; 25: 101–105) was reviewed and actualized according to current publications, legal requirements and conditions in Germany. For the first time this guideline was generated in consensus with the neuroblastoma study group of the Association of Paediatric Haematologie and Oncology (GPOH) with the result of an interdisciplinary recommendation. Further main alterations are related to the recommended 123I activities with respect to the new EANM Paediatric Dosage Card and the explicit recommendation of SPECT.
Effect of phosphorus‐nitrogen additives on fire retardancy of rigid polyurethane foams
Authors: Singh Harpal , Jain A. K. , Sharma T. P. 
Published: May 2008

AbstractA flame retardant composition was prepared from phosphorus‐melamine‐urea‐formaldehyde (PMUF) reaction. The flame retardancy of rigid polyurethane foam (RPUF) was studied by impregnating it with various concentrations of PMUF. Optimum impregnation time, retention and density of RPUF samples with PMUF were also studied. The morphology, elemental analysis, and thermal stability of RPUF and RPUF‐PMUF samples were studied with scanning electron microscopy (SEM), CHNS analyzer, and energy dispersive X‐rays (EDX) and, thermogravimetric analysis (TGA), derivative thermogravimetric (DTG), differential thermal analysis (DTA), respectively. The deposition of PMUF on the cell walls and surfaces was exhibited by decreased cell size from 357 to 285 (±5) μm. CHNS and EDX studies show the introduction of phosphorus and nitrogen into the RPUF‐PMUF samples. The degradation of RPUF and RPUF‐PMUF samples was occurred through two and three stages in nitrogen and air, respectively. RPUF‐PMUF samples are decomposed comparatively at lower temperature than RPUF which is resulted into large amount of high temperature stable char residue. This char residue acts as insulating blanket and protects RPUF‐PMUF from fire. Fire performance and smoke density of RPUF and RPUF‐PMUF samples were investigated with BS: 4735, ASTM D2863 and ASTM E662, respectively. RPUF‐PMUF samples demonstrate reduced extent burnt from 125 to 27 mm, burning rate 2.23–0.44 mm/s and percent mass loss (PML) from 100 to 8.82%. Oxygen index was also increased from 17.8 to 23.8. Dm results obtained during smoke density tests show that RPUF‐PMUF generates less and delayed smoke than RPUF under flaming and nonflaming mode. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Fundamental properties of rhythm sequences
Authors: Egghe Leo , Liang Liming , Rousseau Ronald 
Published: May 2008

AbstractFundamental mathematical properties of rhythm sequences are studied. In particular, a set of three axioms for valid rhythm indicators is proposed, and it is shown that the R‐indicator satisfies only two out of three but that the R′‐indicator satisfies all three. This fills a critical, logical gap in the study of these indicator sequences. Matrices leading to a constant R′‐sequence are called baseline matrices. They are characterized as matrices with constant w‐year diachronous impact factors. The relation with classical impact factors is clarified. Using regression analysis matrices with a rhythm sequence that is on average equal to 1 (smaller than 1, larger than 1) are characterized.