bluuebunny/crossref_metadata_2025_split huggingface dataset:
The temperatures at scuffing and seizure in a four‐ball contact
Authors: Wisniewski M. , Szczerek M. , Tuszynski W. 
Published: July 2006

AbstractThe temperature of surface asperities affects lubricant‐surface tribochemical interactions. It is important to know the nature of this to identify ways of preventing scuffing and seizure under extreme‐pressure (EP) conditions. A new model for the determination of the temperature of contacting asperities is presented in this paper. It assumes the superposition of thermal processes occurring on the macroscale and thermal phenomena in the contact of asperity tips (microscale). Numerical results have been obtained for conditions of four‐ball testing of various lubricating oils — a mineral base oil with and without antiwear and EP additives. To calculate the scuffing and seizure temperatures, knowledge of the mechanical and physical properties of the test ball material (bearing steel) and lubricants, as well as the parameters describing the surface topography of the balls, was necessary. Friction coefficient curves were also needed; they were determined during four‐ball tests with a continuously increasing load. For the base oil with lubricating additives, the temperature of contacting surface asperities at the moment of scuffing initiation was calculated to be about 230°C and increased to over 1000°C at the highest loading of the four‐ball tribosystem. This suggests the possibility of tribochemical reactions of the lubricating additives with the steel surface, and diffusion of some elements, a modified surface layer having good antiseizure properties being produced. Such a layer prevents seizure of the tribosystem. For the base oil without lubricating additives, scuffing initiated at about 150°C and the temperature exceeded 1200°C at seizure. The temperature values obtained agree with results in the literature.
Tribochemistry of aluminium and aluminium alloy systems lubricated with liquids containing alcohol or amine additive types and some other lubricants — a review
Authors: Kajdas C. , Liu W. 
Published: July 2006

AbstractThe ability of a lubricating oil to reduce wear and prevent damage of interacting solids is a crucial factor controlling lubricant formulation. It is well known that friction produces local high temperatures. Many chemical reactions that are initiated by the friction process itself occur at much lower temperatures than those needed to provide the activation energy. Under boundary lubrication conditions, a clean surface exposed as a result of mechanical activity of the solid surface is extremely reactive, especially in the case of metals. This review mostly relates to the tribochemistry of aluminium, and discusses the tribological characteristics of alcohol‐ and amine‐type liquids used as either additives or lubricants to lubricate aluminium and its alloys under boundary friction conditions. Although tribochemical reactions during sliding are perceived in various ways, here the emphasis is on the negative‐ion‐radical action mechanism (NIRAM) approach. This review addresses the question as to how present knowledge of tribochemistry can be applied to the elucidation of the mechanisms of action by which the boundary lubricant compounds considered reduce aluminium‐on‐aluminium, steel‐on‐aluminium, and aluminium‐on‐steel wear. Also, information and a discussion on the tribological behaviour of other additives and/or lubricants in relation to the friction and wear of aluminium and its alloys are presented. A concise review of the most recent work on the tribochemistry of selected fluorinated alcohols is also included.
Action mechanisms of boundary lubrication additives — A review, Part I
Authors: Choudhary R. B. , Jha M. K. 
Published: July 2006

AbstractA wide range of literature has been published in the period 1950–2000 concerning emerging concepts relating to the action mechanisms of boundary lubrication additives. Some of the details of these additives in terms of chemical nature, surface adsorption, surface film generation, thermal stability, thermodynamics of contact surfaces, and rise in surface temperature, as reported in this literature, are reviewed in the present paper. It has been observed that the chemical constituents of boundary lubrication additives, particularly of organosulphur and organosulphur—phosphorus origin, are very complex in nature and no comprehensive details are readily available. Regarding action mechanisms, different researchers have suggested different mechanisms for different conditions. However, information on the thermodynamics of surfaces and thermal stability of additives is not readily available. Other details, such as the effect of sliding speed, operating load, surface roughness, and material design, are not covered in this paper. Overall, the literature reveals that attempts to correlate additive characteristics with boundary lubrication activity have met with limited success, and efforts aimed at achieving ever‐increasing performance levels are continuing.In this first part, the authors examine the chemical nature of boundary lubrication additives, the surface films produced, and surface temperature.
The influence of soot and dispersant on ZDDP film thickness and friction
Authors: Ratoi M. , Castle R. C. , Bovington C. H. , Spikes H. A. 
Published: July 2006

AbstractThe effect of dispersed soot in engine oils is an increasingly important issue in terms of both engine durability and fuel efficiency. Using carbon black as a soot analogue, a study has been carried out to investigate the main factors that determine the impact of soot on friction and ZDDP film formation in formulated oils. It has been found that dispersed carbon black can rapidly remove ZDDP reaction films by abrasion. However, this removal can be prevented or limited by the choice of an optimal dispersant additive.
Pressure distribution in a curvilinear hydrostatic bearing lubricated by a micropolar fluid in the presence of a cross magnetic field
Authors: Walicka A. , Walicki E. 
Published: July 2006

AbstractThe flow of a micropolar fluid in the clearance of a curvilinear hydrostatic thrust bearing in the presence of a cross magnetic field was considered. By solving the equations of motion for the orthogonal curvilinear coordinate system, a formula describing the pressure distribution was obtained. Plane and spherical thrust bearings were considered as examples.
The effect of ZDDP and MoDTC additives in engine oil on the friction properties of DLC‐coated and steel cam followers
Authors: Kano M. , Yasuda Y. , Ye J. P. 
Published: July 2006

AbstractFriction tests simulating cam follower sliding conditions were conducted using a pin‐on‐disc test rig. In the case of SAE 5W‐30 class engine oil, the friction coefficient of the combination of steel pins sliding on a steel disc increased from 0.11 to 0.12, while that of steel pins sliding on a diamond‐like carbon (DLC)‐coated disc decreased from 0.12 to 0.10. For 5W‐20 oil containing the friction modifier MoDTC (molybdenum dithio‐carbamates), the friction coefficient of steel pins sliding on a steel disc decreased markedly from 0.12 to 0.04. In contrast, that of steel pins sliding on a DLC‐coated disc decreased more moderately, from 0.11 to 0.08. In both cases, Zn, P, S, and Mo elements derived from ZDDP (zinc dialkyldithiophosphate) and MoDTC additives were not detected on the DLC‐coated disc, while these elements were detected on the steel disc and pins using electron probe microanalysis and X‐ray photo‐electron spectroscopy surface analysis. It appears that a tribochemical reaction film did not form on the DLC material due to its inactive chemical properties. Therefore, an increase in friction due to the formation of the film derived from ZDDP and a decrease in friction due to the formation of the film derived from MoDTC were clearly suppressed in the case of the steel pins sliding on the DLC‐coated disc. It is thought that the tribo‐chemical reaction film was instrumental in reducing friction substantially. The lateral force of the film formed on the steel disc was then measured using an atomic force microscopy lateral force microscopy test. The lateral force of the film resulting from the 5W‐30 oil was much higher than that of the film formed from the 5W‐20 oil with MoDTC. This result coincided well with the results of the friction tests. Judging from these results, it is thought that the high friction coefficient observed for the steel pins on the steel disc for the 5W‐30 oil was caused by the higher shear strength of the film formed from ZDDP. On the other hand, the very low friction coefficient observed for the steel pin‐steel disc combination for the 5W‐20 oil was presumably caused by the formation of a solid MoS2 lubricant from the MoDTC additive.
Low level laser therapy partially restores trachea muscle relaxation response in rats with tumor necrosis factor α‐mediated smooth airway muscle dysfunction
Authors: Aimbire F. , Bjordal J.M. , Iversen V.V. , Albertini R. , Frigo L. , Pacheco M.T.T. , Castro‐Faria‐Neto H.C. , Chavantes M.C. , Labat R.M. , Lopes‐Martins R.A.B. 
Published: July 2006

AbstractBackground and ObjectiveIt is unknown if the decreased ability to relax airway smooth muscles in asthma and other inflammatory airways disorders can be influenced by low level laser therapy (LLLT) irradiation. To investigate if LLLT could reduce impairment in inflamed trachea smooth muscles (TSM) in rats.Study Design/Materials and MethodsControlled rat study where trachea was dissected and mounted in an organ bath apparatus with or without a TNF‐α solution.ResultsLow level laser therapy administered perpendicularly to a point in the middle of the dissected trachea with a wavelength of 655 nm and a dose of 2.6 J/cm2, partially restored TSM relaxation response to isoproterenol. Tension reduction was 47.0 % (±2.85) in the laser‐irradiated group compared to 22.0% (±2.21) in the control group (P < 0.01). Accumulation of cAMP was almost normalized after LLLT at 22.3 pmol/mg (±2.1) compared to 17.6 pmol/mg (±2.1) in the non‐irradiated control group (P < 0.01).ConclusionLow level laser therapy partially restores the normal relaxation response in inflamed TSM and normalizes accumulation of cAMP in the presence of isoproterenol. Lasers Surg. Med. 38:773–778, 2006. © 2006 Wiley‐Liss, Inc.
Glass transition of crosslinked polystyrene shells formed on the surface of calcium carbonate whisker
Authors: Sasaki Takashi , Kawagoe Shoko , Mitsuya Hajime , Irie Satoshi , Sakurai Kensuke 
Published: July 2006

AbstractGlass transition of core/shell capsules consisting of calcium carbonate whisker as a core and crosslinked polystyrene as a shell was studied by differential scanning calorimetry. The thickness of the crosslinked shell was in the range of 26–81 nm. The crosslinked shells were revealed to show higher glass transition temperatures (Tg) than the corresponding bulk values. It was revealed that a thicker shell exhibits a lower Tg than a thinner shell, and that capsules without core (hollow capsules) exhibit lower Tg's than the corresponding core/shell capsules. These results suggest that the interfacial molecular interaction plays a role in the segmental relaxation, which is responsible for the glass transition. The difference in Tg between the core/shell and hollow samples was reduced when a coupling agent, methacrylic acid 3‐(trimethoxysilyl)propyl ester, was not included. This also suggests the interfacial effect on Tg. However, the results still suggest that the enhancement of Tg for the present crosslinked shells is not only due to the interfacial effect but also to the effects of chain configuration and heterogeneous crosslink. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2475–2485, 2006
Thermal properties and fracture toughness of a liquid‐crystalline epoxy resin cured with an aromatic diamine crosslinker having a mesogenic group
Authors: Harada Miyuki , Watanabe Yutaka , Tanaka Yuko , Ochi Mitsukazu 
Published: July 2006

AbstractA mesogenic‐type curing agent was synthesized to introduce a mesogenic group not only into epoxy resin backbones but also into the crosslink units. In the mesogenic curing agent system, the domain size became larger, and the network arrangement in each domain existed to a greater extent than that in a system cured with the ordinary diamine curing system according to the evidence from polarized optical micrographs and polarized Fourier transform infrared mapping measurements. Moreover, the fracture toughness of the system was considerably improved. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2486–2494, 2006
KL4‐surfactant prevents hyperoxic and LPS‐induced lung injury in mice
Authors: Kinniry Paul , Pick Jeremy , Stephens Scott , Jain Deepika , Solomides Charalambos C. , Niven Ralph , Segal Robert , Christofidou‐Solomidou Melpo 
Published: July 2006

AbstractKL4‐surfactant contains the novel KL4 peptide, sinapultide, which mimics properties of the hydrophobic pulmonary surfactant protein SP‐B, in a phospholipid formulation and may be lung protective in experimental acute respiratory distress syndrome/acute lung injury. Our objective was to determine the protective role of airway delivery of KL4‐surfactant in murine models of hyperoxic and lipopolysaccharide (LPS)‐induced lung injury and further explore the mechanisms of protection. For the hyperoxic injury model, mice exposed to 80% O2 for 6 days received an intranasal bolus of vehicle, beractant, or KL4‐surfactant on days 3, 4, 5, and 6 of the exposure, and lungs were evaluated on day 7. Mice in the LPS‐induced lung injury model received an intratracheal bolus of LPS followed by an intranasal bolus of KL4‐surfactant or control at 1, 3, and 19 hr post‐LPS challenge, and lungs were evaluated after 24 hr. To explore the mechanisms of protection, in vitro assays were performed with human and murine endothelial cell monolayers, and polymorphonuclear leukocyte (PMN) transmigration in the presence or absence of KL4‐surfactant or lipid controls was evaluated. Based on morphology, histopathology, white blood cell count, percentage of PMNs, and protein concentration in bronchoalveolar lavage fluid, our data showed KL4‐surfactant, unlike vehicle or beractant, blocked neutrophil influx into alveoli and suppressed lung injury. Furthermore, in vitro assays showed KL4‐surfactant decreased neutrophil transmigration at the endothelial cell level. KL4‐surfactant decreased inflammation and lung permeability compared with controls in both mouse models of lung injury. Evidence suggests the anti‐inflammatory mechanism of the KL4‐peptide is through inhibition of PMN transmigration through the endothelium. Pediatr Pulmonol. 2006, 41:916–928. © 2006 Wiley‐Liss, Inc.
Modifications to HEDIS and CSTE algorithms improve case recognition of pediatric asthma
Authors: Wakefield Dorothy B. , Cloutier Michelle M. 
Published: July 2006

AbstractOur objective was to validate the Council of State and Territorial Epidemiologists (CSTE) definition of “probable” asthma and the Health Plan Employer Data and Information Set (HEDIS) definition of persistent asthma for diagnosis of pediatric asthma, and examine modifications that improve case recognition. CSTE and HEDIS criteria were applied to a cross‐sectional study of 3,905 Medicaid children with physician‐confirmed diagnosis of asthma/no asthma using a validated survey instrument based upon National Asthma Education and Prevention Program (NAEPP) Guidelines. Modified criteria were applied to another group of 1,458 non‐Medicaid children from a managed care organization (MCO). Of 1,852 Medicaid children with physician‐confirmed asthma, 906 had persistent asthma. CSTE identified 61% of children with “probable” asthma; HEDIS identified 44% of children with persistent asthma. Correct identification increased with greater disease severity. A modified CSTE increased sensitivity from 0.61 to 0.90, while maintaining high specificity. Three new HEDIS algorithms increased sensitivity from 0.44 to >0.84, with specificity >0.89. When applied prospectively to MCO children, these new algorithms demonstrated improved sensitivity. In conclusion, studies using current CSTE or HEDIS algorithms for case recognition underestimate asthma prevalence and overestimate asthma severity in children. Modified algorithms improve the identification of “probable” and persistent asthma. Pediatr Pulmonol. 2006, 41:962–971. © 2006 Wiley‐Liss, Inc.
Bogoliubov‐normal interaction and calculation of thermal conductivity of superfluid A1‐3He
Authors: Afzali R. , Ebrahimian N. 
Published: July 2006

AbstractThe diffusive thermal conductivity tensor of the A 1‐phase of superfluid 3He at low temperatures and melting pressure are calculated by s‐p approximation, by using the Boltzmann equation approach. We obtain that the elements of the diffusive thermal conductivities, Kxx, Kyy, and Kzz, are proportional to T –1. Then we compare the results of this paper and our results of thermal conductivity based on Pfitzner procedure. Temperature dependence of both results is equal but numerical coefficients of them are little different. Also we show that Boguliubov‐normal interaction is important in comparison to other interactions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Weak‐field thermal Hall conductivity of YBa2Cu3O6.99 at low temperature
Authors: Shahzamanian A. , Yavary H. , Yousefvand A. 
Published: July 2006

AbstractWe calculate the thermal Hall conductivity of YBa2Cu3O6.99 by using Kubo formula approach. The longitudinal thermal conductivity, Kxx,is calculated and then by the relation between Kxx and Kxy the thermal Hall conductivity is evaluated. Our results show an increase in the thermal Hall conductivity with the applied field at low temperatures and weak field, i.e. K xy ∼ T √H. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic of vortices in YBa2Cu3O7–δ single crystal near the temperature of the vortex glass transition by the use of voltage noise measurements
Authors: Bghour M. , Labrag A. , Bouaaddi A. , Abaragh A. , Ramzi A. , Taoufik A. , Senoussi S. 
Published: July 2006

AbstractWe have studied the voltage noise Vn and the voltage noise spectral density SV of YBa2Cu3O7–δ superconductor in the regime of high magnetic field. Our studies were performed in a large range of temperature T (70 K‐90 K) covering the vortex‐glass ‐ vortex‐liquid transition which appears at Tg temperature. The sample is driving by a current I = 1 nA, under a different high magnetic fields H (2.4 T, and 5 T). The noise spectral density noted SV(f) exhibits a 1/fα. Approaching Tg the vortex glass transition, the voltage noise spectral density SV(T) is found to vanish critically according to the critical power law SV ∝ (T‐Tg)x, with x = 1.64 ± 0.1 which represents the critical exponent. The behaviour exhibited by Sv(T) cannot be simply interpreted by thermal fluctuations as we conclude by comparing SV(T) with (dR/dT)2 curve. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Partial substitution of calcium in Bi‐Sr‐Ca‐Cu‐O superconductor
Authors: Sýkorová D. , Smrčková O. , Michna E. 
Published: July 2006

AbstractChemical substitutions may change structural and physical parameters in HTS. Substituents influence formation of Bi‐2223 phase, pinning centers, intergrain connection and change hole carrier concentration. Bulk samples with partial substitution of calcium in Bi3.2Pb0.8Sr4Ca5–yMxCu7Oy by 5 B elements (M = V, Nb, Ta), x = 0–0.8 were prepared by solid state reaction in air. Resistivity and magnetic susceptibility measurements evaluated superconducting properties. Phase composition was checked by X‐ray diffraction (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bi‐based superconductors with nanosized silver dopant
Authors: Sýkorová D. , Jakeš V. , Smrčková O. 
Published: July 2006

AbstractThe effect of nanosized silver on formation and transport properties of Bi‐2223 phase was studied. Samples with nominal composition Bi3.2Pb0.8Sr4Ca5Cu7Ox were prepared by solid state synthesis. Ag as additive was used in three different weight percentage 5, 10 and 15. Ag powder was added to the initial mixture or after second calcination. All samples have critical temperature Tc in the range 108‐109 K. An increase of the Bi‐2223 phase content was observed at Ag concentration 10 wt%. Prolonged sintering time (400 h) improved critical current density Jc(77) above the value of the undoped sample. The values of porosity and density of the long sintered samples demonstrated their densification. The SEM micrographs have shown that addition of the silver improves the connectivity between the grains. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transport in MgB2near critical temperature
Authors: Vašek P. 
Published: July 2006

AbstractLongitudinal and transverse voltages have been studied on samples of MgB2. The non‐zero transverse voltage has been observed in close vicinity of critical temperature in zero external magnetic field while far enough from Tc this voltage has been zero. It merges into transverse even voltage in magnetic field which is suppressed with increasing field and increasing transport current as well. New scaling between transverse and longitudinal resistivities has been observed in the formρxy∼ dρxx/dT. Several models trying to explain observed results are discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Changing an insulating state with Wigner‐like correlations into a superconductor with applications to doped fullerides
Authors: Squire Richard H. , March Norman H. 
Published: July 2006

AbstractWe propose a microscopic mechanism for superconductivity in an alkali‐metal doped fulleride. Support is given for the notion that a fulleride doped with two electrons exhibits Wigner‐like correlations. Doping a third electron into this system leads to a transition to superconductivity. The present work has expanded interactions to include not only Wigner‐like correlations between electrons, but also phonons and plasmons. The strength and influence of the numerous interactions are discussed. In the latter context, a “Marel plot” is briefly considered along with electron energy loss measurements. Lastly, we propose that a “soft” electron‐pair quasi‐particle is involved in pairing. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Orbital‐dependent representation of the correlation energy functional: Properties of second‐order Kohn–Sham perturbation expansion
Authors: Engel E. , Jiang H. 
Published: July 2006

AbstractExchange‐correlation energy functionals depending on the Kohn–Sham (KS) orbitals and eigenvalues promise to resolve some of the most pressing deficiencies of the local density and generalized gradient approximations. Such functionals can be derived in first‐principles fashion by use of standard many‐body techniques, using the KS single‐particle Hamiltonian as noninteracting reference Hamiltonian. In this way, one can establish an exact relation for the exchange‐correlation functional, which provides several options for the derivation and treatment of approximate functionals. Straightforward expansion in powers of the electron–electron coupling constant gives, to first order, the exact exchange of density functional theory (DFT) and, to second order, the simplest first‐principles correlation functional. The properties of this second‐order correlation functional are reviewed in detail. It is demonstrated that this functional reproduces both the shell structure in the exact correlation potential and dispersion effects. In response to the variational instability of the functional, observed for the Be atom, a simple and computationally efficient extension is suggested and is shown to be quite accurate for the atomic systems considered so far. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006