Rubber friction: role of the flash temperature

When a rubber block is sliding on a hard rough substrate, the substrate asperities will exert time-dependent deformations of the rubber surface resulting in viscoelastic energy dissipation in the rubber, which gives a contribution to the sliding friction. Most surfaces of solids have roughness on many different length scales, and when calculating the friction force it is necessary to include the viscoelastic deformations on all length scales. The energy dissipation will result in local heating of the rubber. Since the viscoelastic properties of rubber-like materials are extremely strongly temperature dependent, it is necessary to include the local temperature increase in the analysis. At very low sliding velocity the temperature increase is negligible because of heat diffusion, but already for velocities of order 0.01 m/s the local heating may be very important. Here I study the influence of the local heating on the rubber friction, and I show that in a typical case the temperature increase results in a decrease in rubber friction with increasing sliding velocity for v > 0.01 m/s. This may result in stick-slip instabilities, and is of crucial importance in many practical applications, e.g., for the tire-road friction, and in particular for ABS-breaking systems.Comment: 22 pages, 27 figure

Olprinone Attenuates the Acute Inflammatory Response and Apoptosis after Spinal Cord Trauma in Mice

BACKGROUND: Olprinone hydrochloride is a newly developed compound that selectively inhibits PDE type III and is characterized by several properties, including positive inotropic effects, peripheral vasodilatory effects, and a bronchodilator effect. In clinical settings, olprinone is commonly used to treat congestive cardiac failure, due to its inotropic and vasodilating effects. The mechanism of these cardiac effects is attributed to increased cellular concentrations of cAMP. The aim of the present study was to evaluate the pharmacological action of olprinone on the secondary damage in experimental spinal cord injury (SCI) in mice. METHODOLOGY/PRINCIPAL FINDINGS: Traumatic SCI is characterized by an immediate, irreversible loss of tissue at the lesion site, as well as a secondary expansion of tissue damage over time. Although secondary injury should be preventable, no effective treatment options currently exist for patients with SCI. Spinal cord trauma was induced in mice by the application of vascular clips (force of 24 g) to the dura via a four-level T5-T8 laminectomy. SCI in mice resulted in severe trauma characterized by edema, neutrophil infiltration, and production of inflammatory mediators, tissue damage, apoptosis, and locomotor disturbance. Olprinone treatment (0.2 mg/kg, i.p.) 1 and 6 h after the SCI significantly reduced: (1) the degree of spinal cord inflammation and tissue injury (histological score), (2) neutrophil infiltration (myeloperoxidase activity), (3) nitrotyrosine formation, (4) pro-inflammatory cytokines, (5) NF-kappaB expression, (6) p-ERK1/2 and p38 expression and (7) apoptosis (TUNEL staining, FAS ligand, Bax and Bcl-2 expression). Moreover, olprinone significantly ameliorated the recovery of hind-limb function (evaluated by motor recovery score). CONCLUSIONS/SIGNIFICANCE: Taken together, our results clearly demonstrate that olprinone treatment reduces the development of inflammation and tissue injury associated with spinal cord trauma

Comparison between three oxaliplatin-based regimens with bevacizumab in patients with metastatic colorectal cancer

Yoshihito Ohhara,1,2 Mitsukuni Suenaga,1 Satoshi Matsusaka,1 Eiji Shinozaki,1 Nobuyuki Mizunuma,1 Toshiharu Yamaguchi3 1Department of Gastroenterology, Cancer Institute Hospital of the Japanese Foundation for Cancer Research, Tokyo, Japan; 2Department of Medical Oncology, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan; 3Department of Gastroenterological Surgery, Cancer Institute Hospital of the Japanese Foundation for Cancer Research, Tokyo, Japan Background: A previous pivotal Phase III study (NO16966) demonstrated the benefit of the addition of bevacizumab (BV) to oxaliplatin-based regimens in metastatic colorectal cancer (MCRC). Our study evaluated the safety and efficacy of three oxaliplatin-based chemotherapy regimens (FOLFOX4 [intravenous twice-bolus and twice-infusional 5-fluorouracil/folinic acid plus oxaliplatin], mFOLFOX6 [intravenous once-bolus and once-infusional 5-fluorouracil/folinic acid plus oxaliplatin], and XELOX [capecitabine plus oxaliplatin]) plus BV in the first-line treatment of MCRC patients.Methods: Patients with MCRC who started treatment between June 2007 and September 2010 were evaluated in this retrospective cohort study. We also evaluated early objective tumor response (EOTR) within 12 weeks, which was defined as a relative change of ≥30% in the sum of the longest diameters of target lesions when compared with baseline. The primary study endpoints were progression-free survival (PFS) and response rate.Results: A total of 185 patients received the following chemotherapy: FOLFOX4 + BV (FF4 arm, n=85), mFOLFOX6 + BV (FF6 arm, n=40), and XELOX + BV (XELOX arm, n=60). The overall response rates were 61.2%, 72.5%, and 75.0% (95% confidence interval: 50.6%–71.8%, 58.0%–87.0%, and 63.7%–86.3%). Median PFS was 18.0, 15.5, and 13.7 months, respectively (log-rank: P=0.254; data cut-off: May 2013). Patients with EOTR (n=117) had significantly better PFS than those without-EOTR (n=68) (17.5 versus 12.7 months, P=0.004).Conclusion: This study suggests that these three BV plus oxaliplatin-based treatments might have comparable benefit in terms of tumor response and PFS. Moreover, EOTR may be a predictive factor for PFS in patients with MCRC. Keywords: bevacizumab, early tumor objective response, oxaliplatin, colorectal cance