bluuebunny/crossref_metadata_2025_split huggingface dataset:
Triboemission as a basic part of the boundary friction regime: A review
Authors: Warsaw C. Kajdas , Furey M. J. , Ritter A. L. , Molina G. J. 
Published: July 2006

AbstractThis paper reviews selected phenomena related to the boundary friction process. The central thrust is on triboemission, defined as emission of electrons, charged particles, photons, etc., under conditions of boundary friction and/or surface damage caused by fracture processes. Low‐energy electrons are one of the most important particle components in triboemission. Accordingly, the triboemission process is of particular significance for (i) the boundary friction process as such, and (ii) the tribochemistry of the boundary lubrication process. This review considers all the major issues of triboemission and related phenomena/processes. It is shown that, in the boundary lubrication regime with hydrocarbon lubricants, charge intensities decrease with an increase in lubricant molecular weight. The paper also includes some recent information concerning research on triboemission along with a newly developed apparatus.
Frictional performance of lithium 12‐hydroxystearate greases with different soap fibre structures in sliding contacts
Authors: Yamamoto Y. , Gondo S. 
Published: July 2006

AbstractThe effect of the fibre structure of the grease on the frictional performance of lithium 12‐hydroxystearate greases with different fibre lengths was investigated in face, line, and point contact sliding tests. At high sliding speeds where the lubrication regime was practically hydrodynamic, the coefficient of friction of the base oil alone was lower than that of the greases. The coefficient of friction was roughly estimated as follows: base oil < long‐fibre grease < medium‐fibre grease < short‐fibre grease. The supply or replenishing capability of the grease played a critical role in maintaining hydrodynamic lubrication. At high contact pressures, the short‐fibre grease was superior in frictional performance to the long‐fibre grease due to the firm fibre network structure of the latter. In mixed and boundary lubrication regimes, the greases were superior in frictional performance to the base oil, since the soap fibres of the greases had a superior load‐carrying capacity. The long‐fibre grease, with a firm fibre structure, offered better frictional performance than the short‐fibre one.
Thermal effects in cylindrical journal bearings of high‐speed gearboxes
Authors: Strzelecki Stanisław , Spałek Jacek 
Published: July 2006

AbstractThe high rotational speeds and loads of gears operating in acceleration gearboxes causes problems related to the correct choice and design of journal or rolling bearings. In the case of journal bearings, these problems are connected with thermoelastohydrodynamic lubrication theory and the dynamics of the bearing system. However, of major importance is the problem of thermal effects in journal bearings. This has been considered for bearings used in a double‐helical gearbox with the pinion and output shaft operating in cylindrical journal bearings. The oil film pressure, temperature, viscosity distributions, and maximum and mean oil film temperatures have been determined. In calculations, laminar adiabatic and turbulent adiabatic models of oil films have been applied. The results of the calculations can be used in the design of cylindrical or other types of journal bearing in rotating machinery, including acceleration or reduction gearboxes.
Effects of lubricant viscosity on the mixed lubrication of a piston ring pack in an internal combustion engine
Authors: Hamatake Toshiro , Wakuri Yutaro , Soejima Mitsuhiro , Kitahara Tatsumi 
Published: July 2006

AbstractA theoretical analysis is presented of the mixed lubrication of a piston ring pack. The analysis comprises Patir and Cheng's average flow model and Greenwood and Tripp's asperity interaction model, and is developed to consider the shear thinning effect of a non‐Newtonian fluid, multigrade lubricant. The friction characteristics of the piston ring pack for both monograde and multigrade lubricants are investigated. It is found that a decrease in the lubricant viscosity is effective in reducing the friction loss, although this increases the boundary friction at the beginning of the expansion stroke. The friction characteristics are markedly affected by the shear thinning effect when multigrade lubricants are used.
Transient thermo‐elastohydrodynamic lubrication of gear teeth
Authors: Mihailidis A. , Panagiotidis K. 
Published: July 2006

AbstractDuring a gear mesh cycle, load, rolling and sliding velocities, curvature, and temperature change rapidly. In this paper, a transient, thermo‐elastohydrodynamic lubrication model is presented that has been used to study the lubrication parameters at 250 contact points along the path of a contact. The working flanks were assumed to be smooth. The line load was calculated at every contact point, using the finite‐element method. Dynamic loading was not considered. The steady‐state temperature field of the working flanks was used to obtain the surface temperature at the inlet of each contact point, determined by an experimental‐analytical method presented previously. In this model, the lubricant is considered to follow the Ree‐Eyring constitutive equation. The influences of both pressure and temperature on density, thermal conductivity, and specific heat of the lubricant are also taken into account. Results are presented for an FZG type A gear pair lubricated with an FVA No. 4 reference oil; these include film shape, pressure and temperature distributions, as well as friction coefficient.
Influence of temperature on the tribochemical reactions of hexadecane
Authors: Kajdas Czeslaw , Makowska Monika , Gradkowski Marian 
Published: July 2006

AbstractThis paper investigates the tribochemical reactions of n‐hexa‐decane proceeding in a tribosystem lubricated by n‐hexadecane at ambient and elevated temperatures. It is hypothesised that, at ambient temperature, reactions are mostly initiated by the mechanical action of the system, and at elevated temperature (200°C) thermochemical reactions should be dominant. An experimental study was performed using a ball‐on‐disc machine with steel‐on‐steel mating elements. To analyse wear tracks, Fourier transform infrared microspectrophotometry (FTIRM) and electron spectroscopy for chemical analysis (ESCA/XPS) were used. To investigate chemical changes in the bulk lubri cant, gas chromatography coupled with mass spectrometry (GC/ MS) was applied. The results provide clear evidence for the hypothesis that two types of oxygenation processes of n‐hexa ‐decane under boundary lubrication conditions should be considered. The first, at ambient temperature, is controlled by the mechanical action and the second is clearly controlled by temperature. The analytical techniques applied gave evidence of the formation of some reaction products from hexadecane under boundary lubrication conditions. These products include compounds having Fe‐O bonding (salts and chelates), carbonyl compounds, and iron carbide.
Tribological behaviour of Langmuir—Blodgett films of polymerised 22‐tricosenoic acid and 22‐tricosenoic acid/CdS nanoparticles
Authors: Zhang Pingyu , Xue Qunji , Du Zuliang 
Published: July 2006

AbstractLangmuir—Blodgett (LB) films of 22‐tricosenoic acid and of 22‐tricosenoic acid polymerised in the presence of an electron beam, and in situ composite LB films of 22‐tricosenoic acid/CdS were prepared. The friction and wear behaviour of the LB films were investigated with a ball‐on‐block one‐way reciprocating friction tester. The structures and morphologies of the LB films were analysed and observed using atomic force microscopy. The wear resistance of the LB films was increased after polymerisation of the acid, and the composite LB film of 22‐tricosenoic acid/CdS showed better wear resistance because the inorganic nanocores of CdS acted to resist wear and to carry load. The LB film of the acid experienced structural changes during the friction process.
Optimisation of molecular structure for traction fluids
Authors: Tsubouchi T. , Hata H. , Yoshida Y. 
Published: July 2006

AbstractAccording to the guidelines for the molecular design of traction base fluids obtained from a previous study, more than 100 chemical compounds have been synthesised. Employing 61 naphthenic compounds whose chemical structures have been clearly identified, the optimisation of molecular structure has been studied regarding the compatibility of high‐temperature traction coefficient and low‐temperature fluidity. As a result, the requirements for molecular structures for high‐performance traction base fluids have been clarified.
Lubricant oils additivated with polymers in EHD contacts: Part 1. Rheological behaviour
Authors: Bercea M. , Paleu V. , Bercea I. 
Published: July 2006

AbstractThis paper reports on the influence of a polymer additive on the traction behaviour of a mineral oil investigated using a two‐disc machine at different temperatures and contact pressures. A semi‐empirical approach was used for determining the effective lubricant rheological parameters ‐ the elastic shear modulus, the viscosity of the lubricant, and the limiting and Eyring stresses ‐ in elastohydrodynamic contacts. Using this approach, the effect of polymer concentration on the rheological parameters that appear in both the Johnson‐Tevaarwerk and Bair‐Winer models was quantified. The influence of operating conditions, such as pressure, oil temperature, and polymer concentration, on the traction coefficient, limiting shear stress (from the Bair‐Winer model), Eyring stress (from the Johnson‐Tevaarwerk model), shear modulus, and apparent viscosity was also investigated.
Tribological properties and tribochemical mechanism of lanthanum and boron compounds in oil
Authors: Jiang S. , Wei Y. L. , Cheng X. Y. , Chen B. S. 
Published: July 2006

AbstractLanthanum dialkyldithiophosphate (LaDDP) was synthesised. The tribological properties of a combination additive of LaDDP and an organo‐borate (OB) in oil were evaluated with a four‐ball test machine. The results show that the combination of LaDDP and OB gives better load‐carrying capacity and anti‐wear and friction‐reducing properties than the individual components. Rubbed surfaces after the friction tests were investigated using X‐ray photoelectron spectroscopy, Auger electron spectroscopy, and microhardness testing. The results indicate that a boundary film is composed of deposit films (including La2O3 and B2O3), chemical reaction films (including FeSO4, FePO4, and FeS), and a tribodiffusion layer (including La and B). Lanthanum can promote the decomposition of OB and the tribodiffusion of boron. From a mass spectroscopy analysis a tribochemical mechanism is suggested.
Action mechanisms of boundary lubrication additives ‐ a review, part II
Authors: Choudhary R. B. , Jha M. K. 
Published: July 2006

AbstractA wide range of literature hs been published in the period 1950–2000 concerning emerging concepts of the action mechanisms of boundary lubrication additives. Some aspects 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.Part I of this paper appeared in Lubrication Science, 16, 4 (2004) 405–19.
It has been observed that the chemical constituents of boundary lubrication additives, particularly of organosulphur and organo‐sulphur‐phosphorus origin, are very complex in nature and no comprehensive details are readily available. Regarding action mechanisms, researchers have suggested different mechanisms for different conditions. However, information on the thermodynamics of surfaces and thermal stability of additives is not easily obtainable. Other details, such as the effect of sliding speed, operating load, surface roughness, and material design, are not covered here. 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 continue.In the first part, the authors examined the chemical nature of boundary lubrication additives, surface films, and surface temperature. In this second part, they look at thermal stability, and antiwear and extreme‐pressure activity.
Extending the retention of friction‐reducing capability in low‐phosphorus engine oils
Authors: Jensen R. 
Published: July 2006

AbstractIn advanced fuel‐efficient engine oils containing molybdenum dialkyldithiocarbamate, Mo(dtc)2, as a friction‐reducing additive, the friction‐reducing capability is gradually depleted with mileage accumulation and is dependent on the presence of other additives, such as zinc dialkyldithiophosphate, Zn(dtp)2. Indeed, it has been shown that the loss of the friction‐reducing capability of Mo(dtc)2 coincides with the depletion of Zn(dtp)2. The next generation of oils will specify a lower phosphorus content (e.g., 0.08% in ILSAC GF‐4 and even lower in the specification after GF‐4) to reduce the detrimental effects of phosphorus on catalyst systems. This will necessitate the use of less Zn(dtp)2, which could have an adverse effect on the retention of friction‐reducing capability.The aim of this study was to determine if the retention of friction‐reducing capability could be maintained or even increased at 0.05% phosphorus with newer molybdenum trinuclear, Mo3S7(dtc)4, additives. To facilitate the study, a modified laboratory‐based ageing test was developed which correlated with the loss of friction‐reducing capability in the Sequence VIB engine test. This ageing test was used to evaluate model blends of Mo3S7(dtc)4 with Zn(dtp)2 at 0.05% phosphorus and added antioxidants. The results indicate that it is possible to extend the retention of friction‐reducing capability. However, whether or not it can be extended beyond the current drain intervals is still an open question.
An extended FE strategy for transition from continuum damage to mode I cohesive crack propagation
Authors: Comi Claudia , Mariani Stefano , Perego Umberto 
Published: July 2006

AbstractAn integrated strategy is proposed for the simulation of damage development and crack propagation in concrete structures. In the initial stage of damage growth, concrete is considered to be macroscopically integer and is modeled by a non‐symmetric isotropic non‐local damage model. The transition to the discrete cohesive crack model depends on the local mesh size and is driven by an analytical estimate of the current bandwidth. When a crack is introduced in the model an extended finite element approach is used to follow the propagation path, independent of the background mesh. The proposed methodology is tested on a notched tension specimen and then applied to the analysis of a wedge splitting test. Copyright © 2006 John Wiley & Sons, Ltd.
Effects of molecular characteristics and processing conditions on melt‐drawing behavior of ultrahigh molecular weight polyethylene
Authors: Kakiage Masaki , Yamanobe Takeshi , Komoto Tadashi , Murakami Syozo , Uehara Hiroki 
Published: July 2006

AbstractThe effects of molecular characteristics and processing conditions on melt‐drawing behavior of ultrahigh molecular weight polyethylene (UHMW‐PE) are discussed, based on a combination of in situ X‐ray measurement and stress–strain behavior. The sample films of metallocene‐ and Ziegler‐catalyzed UHMW‐PEs with a similar viscosity average MW of ∼107 were prepared by compression molding at 180 °C. Stress profiles recorded at 160 °C above the melting temperature of 135 °C exhibited a plateau stress region for both films. The relative change in the intensities of the amorphous scattering recorded on the equator and on the meridian indicated the orientation of amorphous chains along the draw axis with increasing strain. However, there was a substantial difference in the subsequent crystallization into the hexagonal phase, reflecting the molecular characteristics, that is, MW distribution of each sample film. Rapid crystallization into the hexagonal phase occurred at the beginning point of the plateau stress region in melt‐drawing for metallocene‐catalyzed UHMW‐PE film. In contrast, gradual crystallization into the hexagonal phase occurred at the middle point of the plateau stress region for the Ziegler‐catalyzed film, suggesting an ease of chain slippage during drawing. These results demonstrate that the difference in the MW distribution due to the polymerization catalyst system dominates the phase development mechanism during melt‐drawing. The effect of the processing conditions, that is, the including strain rate and drawing temperature, on the melt‐drawing behavior is also discussed. The obtained results indicate that the traditional temperature–strain rate relationship is effective for transient crystallization in to the hexagonal phase during melt‐drawing, as well as for typically oriented crystallization during ultradrawing in the solid state. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2455–2467, 2006
Sense of coherence as a protective factor for demoralisation in women with a recent diagnosis of gynaecological cancer
Authors: Boscaglia Nadia , M. Clarke David 
Published: July 2006

AbstractBackground: Demoralisation is a dysphoric mood state commonly seen in the medically ill. Its core features comprise hopelessness, helplessness, loss of purpose and meaning, despair, and existential distress. Sense of Coherence (SOC) is a quantifiable dispositional orientation that captures the character traits likely to protect against demoralisation. In this study, we hypothesised on theoretical grounds that a strong SOC would be associated with lower levels of demoralisation in the context of gynaecological cancer (GC).Method: One hundred and twenty women with a recent (<12 months) diagnosis of GC were recruited from outpatient clinics. Participants were interviewed and completed questionnaire measures of demoralisation and SOC. A multiple regression analysis was performed using the five subscales of the Demoralisation Scale as predictor variables and SOC as the dependent variable.Results: Together, the five subscales of the Demoralisation Scale accounted for 60% of the variance in SOC.Conclusions: The results supported the hypothesis, suggesting that SOC may be protective against demoralisation in the context of serious illness. Larger, multivariate studies that examine additional variables (such as coping) would be required to further clarify the relationship between SOC and demoralisation. In the meantime, clinicians may want to consider efforts to enhance SOC in patients. Copyright © 2006 John Wiley & Sons, Ltd.
Adenovirus pneumonia in infants and factors for developing bronchiolitis obliterans: A 5‐year follow‐up
Authors: Castro‐Rodriguez Jose A. , Daszenies Cecilia , Garcia Marianela , Meyer Rodolfo , Gonzales Ramiro 
Published: July 2006

AbstractTo describe clinical, pulmonary function, and chest tomography profiles in a 5‐year follow‐up of infants with adenovirus pneumonia and determine the factors that potentially contributed to the development of bronchiolitis obliterans (BO). We prospectively assessed 45 hospitalized infants with adenovirus pneumonia with additional follow‐up for 5 years. At the end of the study, pulmonary function by impulse oscillometry technique (IOS) and chest tomography were performed in the 38 surviving patients (mean 5.7 years of age). We divided the population between those who developed chest tomography evidence of BO and those who did not. Most of the children developed adenovirus infection before 2 years of age. During the 5 years of follow‐up, almost half (47.4%) developed BO. Children who developed BO had significantly more respiratory compromise (intensive care admission, need for mechanical ventilation and for oxygen therapy, and systemic corticosteroid and beta agonist use) during their adenovirus pneumonia episode than those who did not develop BO. Only 33.3% of children with BO had normal impedance compared with 85% in the no BO group. Children who developed BO had significantly higher levels of Zrs, R5, X5 and predicted Zrs, R5, and X5 and frequency. However, there were no differences in the beta 2 agonist response between the children with and without BO (94% vs. 80%, respectively). This study represents the spectra of adenovirus pneumonia ranging from relatively mild to severe and fatal cases. Children with severe pulmonary compromise are usually more prone to develop BO. Pediatr Pulmonol. 2006, 41:947–953. © 2006 Wiley‐Liss, Inc.
Quantification of siderophages in bronchoalveolar fluid in transfusional and primary pulmonary hemosiderosis
Authors: Priftis Kostas N. , Anthracopoulos Michael B. , Tsakanika Constantina , Tapaki Georgia , Ladis Vassilis , Bush Andrew , Nicolaidou Polyxeni 
Published: July 2006

AbstractTransfusional iron overload may occur in the lungs. We hypothesized that quantitating siderophages in the bronchoalveolar fluid (BALF) of heavily transfused patients may prove to be a useful tool in determining lung iron overload in transfusion‐dependent patients. The study included six patients (7–20 years) with thalassemia major (TM) who had received multiple blood transfusions, one with hereditary spherocytosis (four blood transfusions) and one with sickle cell disease (never transfused); they were compared to three children with idiopathic pulmonary hemosiderosis (IPH) (2.5–7.0 years) as positive controls. Fiberoptic bronchoscopy with bronchoalveolar lavage was performed in seven patients under general anesthesia for elective surgery and the rest were bronchoscoped electively under sedation. Spirometry was also performed in eight patients. There was no significant difference between children with TM and IPH in siderophages as percentage of total count (95% CI −31.0 to 1.5, P = 0.068). There were positive relationships between both mean serum ferritin values during the preceding year and the total number of units of transfused blood, and percent siderophage count among multiply transfused patients (P = 0.010, P = 0.052, respectively); similar findings were noted for the Golde score (P = 0.001, P = 0.031, respectively). None of the patients showed lung function impairment. In conclusion, in this small study, we found that the BALF of multiply transfused patients with benign hematological disorders contain similar numbers of siderophages to that of patients with IPH; this is strongly suggestive of secondary pulmonary hemosiderosis. The correlation between the patients' serum ferritin, and the BALF siderophages suggests that the later may serve as a marker of pulmonary iron overload in patients requiring blood transfusion and appear to be more sensitive than standard pulmonary function tests. Pediatr Pulmonol. 2006, 41:972–977. © 2006 Wiley‐Liss, Inc.
Magnetic history dependence of the AC susceptibility of GdSr2RuCu2Oz
Authors: Polichetti M. , Adesso M. G. , Zola D. , Vecchione A. , Gombos M. , Ciancio R. , Fittipaldi R. , Cimberle M. R. , Pace S. 
Published: July 2006

AbstractThe AC susceptibility of GdSr2RuCu2Oz samples has been measured as function of the temperature, at different AC field amplitudes (from 1 to 16 G) and frequencies (in the range [10‐103 Hz]), applied parallel to the major axis of the sample, and without any additional DC magnetic field. In particular we have analysed the temperature region above the Superconducting critical temperature Tc, and around the magnetic transition temperature Tm. Our attention has been focused on the differences between the curves measured after cooling the sample in zero AC field (Zero AC Field Cooling or ZAFC) and those measured after cooling in presence of a non zero AC field (AC Field Cooling or AFC). Clear differences between the ZAFC and AFC susceptibility curves appear in the temperature range between Tc and Tm, and they depend on the measuring field amplitude and frequency. Finally, indications of a spin glass behaviour in Ru‐1212 system observed from its AC magnetic response are reported (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)