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The phase diagrams corresponding to transition from liquid to viscoelastic solid and that from viscoelastic solid to elastic-plastic solid of Santotrac100 (SN100), mineral oil, synthetic naphthenic oil, polybutene, and tetradecane were first made up by high-pressure density measurements and others. The bulk modulus of lubricating oils under a quasi-static condition was evaluated using a phase diagram. The results indicated that the bulk modulus of lubricating oils is closely related to the oil molecular packing parameter T VE -T (where T VE is the viscoelastic solid transition temperature at pressure p, and T is the oil temperature). The constant values of the bulk modulus in the elastic-plastic range are different depending on the molecular structures of the oils. It has also been shown that SN100, mineral oil, synthetic naphthenic oil, and polybutene converted to amorphous solids at high pressures and tetradecane converted to molecular crystal. Next, the elastohydrodynamic lubrication tractions were measured by a ball-on-disk machine. The results indicated that the maximum traction coefficient is closely related to T VE -T. As a result, the importance of the bulk modulus as a predominant factor for traction characteristics of lubricating oil was pointed out. [ABSTRACT FROM AUTHOR]

Background The aims of this study were to estimate the prevalence of Delayed Sleep Phase Syndrome (DSPS) in adolescence, and to examine the association to insomnia and school nonattendance. Methods Data stem from a large population based study in Hordaland County in Norway conducted in 2012, the ung@hordaland study. In all, 10,220 adolescents aged 16-18 years (54% girls) provided self-reported data on a range of sleep parameters: DSPS was defined according to the International Classification of Sleep Disorders, Revised (ICSD-R) criteria, while insomnia was defined according to the Quantitative Criteria for Insomnia. Other sleep parameters included time in bed, sleep duration, sleep efficiency, oversleeping, sleep onset latency, wake after sleep onset, subjective sleep need, sleep deficiency, sleepiness and tiredness. Sleep data were calculated separately for weekdays and weekends. Data on school non-attendance were provided by official registers. Results The prevalence of DSPS was 3.3%, and significantly higher among girls (3.7%) than boys (2.7%). There was a strong overlap between DSPS and insomnia, with more than half of the adolescents with DSPS also meeting the criteria for insomnia (53.8% for boys and 57.1% for girls). Adolescents with DSPS had significantly higher odds ratios (OR) of non-attendance at school. After adjusting for sociodeographical factors, insomnia and depression, the adjusted ORs for days of non-attendance were OR = 3.22 (95% CI: 1.94-5.34) for boys and OR = 1.87 (95% CI: 1.25-2.80) for girls. A similar effect was found for hours of non-attendance for boys, with an adjusted OR = 3.05 (95% CI: 1.89-4.92). The effect for girls was no longer significant after full adjustment (OR =1.48 [95% CI: 0.94-2.32]). Conclusions This is one of the first studies to estimate the prevalence of DSPS in adolescents. The high prevalence of DSPS, and overlap with insomnia, in combination with the odds of school nonattendance, suggest that a broad and thorough clinical approach is warranted when adolescents present with symptoms of DSPS. [ABSTRACT FROM AUTHOR]

The efficacy of oil blends containing zinc dialkyl dithiophosphate (ZnDTP) and molybdenum (Mo)-complex additives to improve the tribological properties of boundary-lubricated steel surfaces was investigated experimentally. The performance of oil blends containing three different types of Mo-complex additives of varying Mo and S contents with or without primary/secondary ZnDTP additions were investigated at 100°C. The formation of antiwear tribofilms was detected in situ by observing the friction force and contact voltage responses. Wear volume and surface topography measurements obtained from surface profilometry and scanning electron microscopy studies were used to quantify the antiwear capacity of the formed tribofilms. The tribological properties are interpreted in terms of the tribofilm chemical composition studied by X-ray photoelectron spectroscopy. The results demonstrate that blending the base oil only with the Mo-compound additives did not improve the friction characteristics. However, an optimum mixture of Mo complexes and ZnDTP additive provided sufficient amounts of S and Mo for the formation of antiwear tribofilms containing low-shear strength MoS 2 that reduces sliding friction. In addition, the formation of a glassy phosphate phase due to the synergistic effect of the ZnDTP additive enhances the wear resistance of the tribofilm. This study shows that ZnDTP- and Mo-containing additives incorporated in oil blends at optimum proportions improve significantly the tribological properties of boundary-lubricated steel surfaces sliding at elevated temperatures. [ABSTRACT FROM AUTHOR]

Objectives: The aim was to study the persistence and characteristics of Staphylococcus warneri strains resistant to quaternary ammonium compounds (QACs), including sequencing and analysis of two plasmids proved to carry the smr gene.Methods: During a 3.5 year period quarter milk samples were collected on three occasions from all lactating cows in a dairy herd. The samples were screened with regard to QAC-resistant bacteria using a selective medium. Thirty randomly selected QAC-resistant S. warneri were typed by PFGE and subjected to plasmid isolation and analysis followed by gene detection using PCR. Two smr-containing plasmids in S. warneri isolates were sequenced.Results: All isolates from the initial collection of quarter milk contained smr residing on a 5.8 kb plasmid (pSW174), which contained regions with high similarities to various plasmids, including pT181, pSK108 and pPI-2. The pT181-like sequence was flanked by 148 bp direct repeats, denoted ISLE49, with high similarity to previously reported sequences of ~148 bp, including ISLE39 flanking the insertion sequence IS257 in methicillin-resistant Staphylococcus aureus. All isolates from subsequent collections of quarter milk harboured a smaller smr-containing plasmid (pSW49). Sequence analyses revealed pSW49 (3552 bp) to be an in-part deleted version of pSW174 (5767 bp).Conclusions: The IS-associated elements found in this study may have a wider role in the integration and excision of DNA sequences in staphylococci than previously reported. The mosaic plasmid structure based on genetic elements of various origins contributes to further knowledge on the flexibility of smr-encoding plasmids. [ABSTRACT FROM AUTHOR]

Background. Chronic morphological changes in the kidney allograft predict long-term graft function, but there are few studies comparing different methods in assessing chronic lesions. In the present study, we evaluated allograft cortical interstitial fibrosis, and compared semiquantitative assessment with computerized image analysis of Sirius red-stained collagen in prediction of graft prognosis.Methods. Sections were obtained from a series of 1-year protocol living donor kidney graft biopsies (n = 33) and their corresponding baseline specimens (n = 32). At light microscopy, the biopsies were scored for interstitial fibrosis as a percentage of involved tubulointerstitium according to the Banff schema. Quantitation of cortical fractional interstitial fibrosis volume (Vint) was performed with computerized image analysis on coded sections stained with Sirius red. The results were correlated with kidney function at 810 years after transplantation, and with late graft loss.Results. There was a significant correlation between the semiquantitative and quantitative methods for measuring cortical interstitial fibrosis in all the biopsies (n = 65, percentage area vs Vint: R = 0.439, P = 0.0003). The correlation further improved when analysing the baseline specimens separately (n = 32, R = 0.704, P<0.0001) and was still significant, but less precise for the 1-year biopsies (n = 33, R = 0.384, P = 0.0274). One-year semiquantitative fibrosis (percentage area) was correlated to serum creatinine at 810 years (P = 0.010) and to late graft loss (P = 0.0445). The 1-year Vint values for interstitial fibrosis showed a similar trend but did not reach statistical significance in prediction of long-term graft function.Conclusions. Image analysis quantitation of interstitial collagen with Sirius red corresponded well to light microscopic semiquantitative assessment of interstitial fibrosis. In prediction of long-term graft function, the semiquantitative method was superior, indicating that accumulation of matrix molecules other than fibrillary collagens, oedema and inflammation are also important in graft prognosis. [ABSTRACT FROM AUTHOR]