| 1. |
- Abbasi, Saeed, 1973-, et al.
(författare)
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Pin-on-disc study of the effects of railway friction modifiers on airborne wear particles from wheel-rail contact
- 2013
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Ingår i: Tribology International. - : Elsevier. - 0301-679X .- 1879-2464. ; 60, s. 136-139
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge of wheel–rail interaction is crucial to wheel and rail maintenance. In this interaction, some of theworn-off material is transformed into airborne particles. Although such wear is well understood, few studiestreat the particles generated. We investigated friction modifiers' effects on airborne particles characteristicsgenerated in wheel-rail contacts in laboratory conditions. Pin-on-disc machine testing with a round-head pinloaded by a dead weight load 40 N simulated maximum contact pressure over 550 MPa. Airborne particlecharacteristics were investigated in dry contacts and in ones lubricated with biodegradable rail grease andwater- and oil-based friction modifiers. The number of particles declined with the grease; the number ofultrafine particles increased with the water-based friction modifier, mainly due to water vaporization.
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| 2. |
- Bergseth, Ellen, 1979-, et al.
(författare)
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Study of surface roughness and surface orientation on friction in rolling/sliding contacts: barrel-on-disc versus twin-disc
- 2017
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Konferensbidrag (refereegranskat)abstract
- Gears are one of the most important means of mechanical power transmission. Even though the efficiency is high for a gear pair today, further decrease in friction can contribute to lower the fuel consumption. A barrel-on-disc machine (same setup as ball-on-disc) to simulate a rolling/sliding gear contact was used to study the impact of manufacturing method, grinding and superfinishing, on friction. To evaluate the extent to which friction and wear can be diminished by reducing surface roughness and changing surface orientation. Measurement results showed that the change of lubricant had an impact on friction in the mixed to boundary lubrication regimes similar to that of the change of main surface orientation. The results were compared with those from a parallel study involving a twin-disc machine, also used to simulate rolling/sliding contacts (see Figure). Measurements and simulations showed that the barrel-on-disc and twin-disc setups reflected the same friction trends. However, the friction coefficient using the barrel-on-disc setup was almost twice as large as that found using the twin-disc machine. The wear mechanisms also differed: micropits occurred on discs used in the twin-disc set-up whereas normal or no wear was found on the barrel-on-disc specimens. The difference in contact geometry is believed to be the main reason for the higher friction level in the barrel-on-disc machine. A computer contact analysis was used to clarify the differences using perfectly smooth and computer-generated textured surfaces.
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| 3. |
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| 4. |
- Bergseth, Ellen, 1979-, et al.
(författare)
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Study of Surface Roughness on Friction in Rolling/Sliding Contacts : Ball-on-Disc Versus Twin-Disc
- 2020
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Ingår i: Tribology letters. - : Springer Science and Business Media LLC. - 1023-8883 .- 1573-2711. ; 68:2
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Tidskriftsartikel (refereegranskat)abstract
- Although the efficiency of a gear pair is currently high, a better understanding of surface/lubricant contribution on efficiency is critical. Electrified drivelines will, for example, impose higher speed and alternate loading, and it is expected that these new conditions will, to a greater extent, rely on the surface/lubricant characteristics. Phenomena taking place in the gear contact is often measured using ball-on-disc and twin-disc tribometers. In this study, these two test set-ups were compared in order to assess differences in the behaviour of surface/lubricant interactions. Results showed that ball-on-disc and twin-disc set-ups reflect the same friction trends. However, the friction results differed by a factor of roughly two, even though the tribometers were set-up to run at the same contact pressure. The wear mechanisms also differed: micropits occurred on discs used in the twin-disc set-up, whereas normal or no wear was found on the ball-on-disc specimens. The contact conditions for the two test set-ups were also analysed using a numerical model. The comparison of these two machines may aid gear designers in selecting the proper experimental set-up for their purpose.
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| 5. |
- Casselgren, Johan, et al.
(författare)
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An optical sensor for the identification of low adhesion in the wheel–rail contact
- 2012
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Ingår i: The international Journal of railway technology. - 2049-5358 .- 2053-602X. ; 1:3, s. 97-110
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Tidskriftsartikel (refereegranskat)abstract
- Low adhesion between railway wheel and rail, usually induced by contaminants such as water, oil, and leaves, affects railway performance and safety. This study uses an optical sensor to identify various surface layers that cause low adhesion. In both a laboratory set-up and field tests under various conditions, the surface layers were identified by the optical sensor; in addition, the friction coefficients for the same surface layers were measured. The results indicate that the sensor can distinguish between different surface layers. This information, together with friction coefficient data, can be used in a prediction system for use by railway operators.
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| 6. |
- Dries, Daniel R., et al.
(författare)
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Loss of Nicastrin from Oligodendrocytes Results in Hypomyelination and Schizophrenia with Compulsive Behavior
- 2016
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 291:22, s. 11647-11656
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Tidskriftsartikel (refereegranskat)abstract
- The biological underpinnings and the pathological lesions of psychiatric disorders are centuries-old questions that have yet to be understood. Recent studies suggest that schizophrenia and related disorders likely have their origins in perturbed neurodevelopment and can result from a large number of common genetic variants or multiple, individually rare genetic alterations. It is thus conceivable that key neurodevelopmental pathways underline the various genetic changes and the still unknown pathological lesions in schizophrenia. Here, we report that mice defective of the nicastrin subunit of gamma-secretase in oligodendrocytes have hypomyelination in the central nervous system. These mice have altered dopamine signaling and display profound abnormal phenotypes reminiscent of schizophrenia. In addition, we identify an association of the nicastrin gene with a human schizophrenia cohort. These observations implicate gamma-secretase and its mediated neurodevelopmental pathways in schizophrenia and provide support for the "myelination hypothesis" of the disease. Moreover, by showing that schizophrenia and obsessive-compulsive symptoms could be modeled in animals wherein a single genetic factor is altered, our work provides a biological basis that schizophrenia with obsessive-compulsive disorder is a distinct subtype of schizophrenia.
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| 7. |
- Du, Yaoyao, et al.
(författare)
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Cartilage Oligomeric Matrix Protein Inhibits Vascular Smooth Muscle Calcification by Interacting With Bone Morphogenetic Protein-2.
- 2011
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Ingår i: Circulation Research. - 1524-4571. ; 108, s. 79-917
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Tidskriftsartikel (refereegranskat)abstract
- Rationale: Vascular calcification is a significant contributor to cardiovascular morbidity and mortality. We recently reported that cartilage oligomeric matrix protein (COMP) is pivotal for maintaining the homeostasis of vascular smooth muscle cells (VSMCs). Whether COMP affects the process of vascular calcification is unknown. Objective: We aimed to test whether COMP modulates vascular calcification. Methods and Results: VSMC calcification in vitro was induced by calcifying media containing high inorganic phosphate or calcium. In vivo medial vessel calcification was induced in rats by 5/6 nephrectomy with a high-phosphate diet or by periadventitial application of CaCl(2) to the abdominal aorta. COMP protein level was markedly reduced in both calcified VSMCs and arteries. COMP deficiency remarkably exacerbated VSMC calcification, whereas ectopic expression of COMP greatly reduced calcification. Furthermore, COMP knockdown facilitated osteogenic markers expression by VSMCs even in the absence of calcifying media. By contrast, COMP overexpression significantly inhibited high phosphate- or high calcium-induced VSMC osteochondrogenic transition. Induction of osteogenic marker expression by COMP silencing was reversed by a soluble form of bone morphogenetic protein (BMP)-2 receptor IA, which suggests a BMP-2-dependent mechanism. Our data revealed that COMP bound directly to BMP-2 through the C terminus, inhibited BMP-2 receptor binding, and blocked BMP-2 osteogenic signaling, indicating COMP inhibits osteochondrogenic transition of VSMCs at least partially through inhibiting BMP-2. Conclusions: Our data strongly suggest that COMP is a novel inhibitor of vascular calcification. The imbalance between the effects of COMP and BMP-2 may provide new insights into the pathophysiology of vascular calcification.
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| 8. |
- Gan, Yong, et al.
(författare)
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Association between alcohol consumption and the risk of stroke in middle-aged and older adults in China
- 2021
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Ingår i: Drug And Alcohol Dependence. - : Elsevier BV. - 0376-8716 .- 1879-0046. ; 229
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This study aimed to investigate the association between alcohol consumption and the prevalence of stroke in Chinese adults aged 40 years and over.Method: We conducted a cross-sectional analysis among 113,573 Chinese adults aged >= 40 years in the China National Stroke Prevention Project (2014-2015) to examine correlations of alcohol consumption with the prevalence of stroke. Logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), controlling for various confounders, e.g., gender, age, smoking, physical activity and other health conditions.Results: Within the study population, a total of 12,753 stroke survivors were identified. The prevalence of light to moderate and of heavy alcohol consumption was 10.1% and 5.7% respectively. The multivariate logistic regression results show that light to moderate alcohol consumption was associated with reduced risk of stroke of all types [0.91 (95%CI: 0.85-0.97)] and of ischemic stroke [0.90 (0.84-0.97)]. No association was found between alcohol consumption and hemorrhagic stroke. Compared with abstainers, the adjusted ORs of all stroke were 0.83 (0.75-0.92) for those who drank 11-20 years, and no association was found between 1 and 10 years or over 20 years of drinking and risk of stroke.Conclusions: These results indicate that light to moderate alcohol consumption may be protective against all and ischemic stroke, and heavy drinking was not significantly associated with risk of all stroke in China. No association between alcohol consumption and hemorrhagic stroke was found.
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| 9. |
- Hsu, Fang-Chi, et al.
(författare)
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A novel prostate cancer susceptibility locus at 19q13.
- 2009
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Ingår i: Cancer research. - 1538-7445. ; 69:7, s. 2720-3
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Tidskriftsartikel (refereegranskat)abstract
- A two-stage genome-wide association study (GWAS) of the Cancer Genetic Markers of Susceptibility (CGEMS) initiative identified single nucleotide polymorphisms (SNP) in 150 regions across the genome that may be associated with prostate cancer (PCa) risk. We filtered these results to identify 43 independent SNPs where the frequency of the risk allele was consistently higher in cases than in controls in each of the five CGEMS study populations. Genotype information for 22 of these 43 SNPs was obtained either directly by genotyping or indirectly by imputation in our PCa GWAS of 500 cases and 500 controls selected from a population-based case-control study in Sweden [Cancer of the Prostate in Sweden (CAPS)]. Two of these 22 SNPs were significantly associated with PCa risk (P<0.05). We then genotyped these two SNPs in the remaining cases (n=2,393) and controls (n=1,222) from CAPS and found that rs887391 at 19q13 was highly associated with PCa risk (P=9.4 x 10(-4)). A similar trend of association was found for this SNP in a case-control study from Johns Hopkins Hospital (JHH), albeit the result was not statistically significant. Altogether, the frequency of the risk allele of rs887391 was consistently higher in cases than controls among each of seven study populations examined, with an overall P=3.2 x 10(-7) from a combined allelic test. A fine-mapping study in a 110-kb region at 19q13 among CAPS and JHH study populations revealed that rs887391 was the most strongly associated SNP in the region. Additional confirmation studies of this region are warranted.
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| 10. |
- Lewis, Roger, et al.
(författare)
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The Modification of a Slip Resistance Meter for Measurement of Railhead Adhesion
- 2013
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Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : Sage Publications. - 0954-4097 .- 2041-3017. ; 227:F2, s. 196-200
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to find a quick, flexible and localised method for determining railhead adhesion. The proposed method is a pendulum rig, which has a rubber pad at the base of a swinging arm. The arm is released and as the rubber pad slides across the contact surface, energy is lost. This loss can be translated into a friction coefficient. Tests have been performed under dry and contaminated conditions, including water, oil and leaf layers both in the laboratory on extracted rail and in the field on live rail. Friction modifiers were also tested. The results of these tests are compared with data obtained using a hand-pushed tribometer. The performed study shows that the pendulum is a viable way to test adhesion levels in the field.
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