Analysis of the Contribution of Adhesion and Hysteresis to Shoe–Floor Lubricated Friction in the Boundary Lubrication Regime

Slip and fall accidents cause frequent occupational injuries. Despite recent evidence that boundary lubrication is relevant to slipping, few studies have examined the mechanisms that contribute to shoe?Cfloor friction in this lubrication regime. This study aims to identify the contributions of adhesion and hysteresis to friction in boundary lubrication. Three shoe materials (40 Shore A hardness polyurethane, 60 Shore A hardness rubber, and 70 Shore A hardness rubber), two floor materials (vinyl and marble), and six lubricants (water, 1.5?% detergent, 25?% glycerol?C75?% water, 50?% glycerol?C50?% water, 75?% glycerol?C25?% water, and canola oil) were tested at a single sliding speed (0.01?m?s^?1). Dry adhesion and hysteresis were quantified for each of the shoe?Cfloor combinations and lubricated adhesion was quantified for all shoe?Cfloor-fluid combinations. The contribution of adhesion and hysteresis to shoe?Cfloor-lubricant friction was affected by both the shoe and floor material due to differences in hardness and roughness. Lubricated adhesion was complex and multifactorial with contributions from the shoe, fluid, shoe?Cfloor interaction, floor-lubricant interaction, and shoe-lubricant interactions. A simple regression model including two fluid coefficients and the dry adhesion friction force was able to predict 49?% of the lubricated adhesion friction variability.     

Climate-change-driven deterioration of water quality in a mineralized watershed

A unique 30-year streamwater chemistry data set from a mineralized alpine watershed with naturally acidic, metal-rich water displays dissolved concentrations of Zn and other metals of ecological concern increasing by 100-400% (400-2000 μg/L) during low-flow months, when metal concentrations are highest. SO(4) and other major ions show similar increases. A lack of natural or anthropogenic land disturbances in the watershed during the study period suggests that climate change is the underlying cause. Local mean annual and mean summer air temperatures have increased at a rate of 0.2-1.2 °C/decade since the 1980s. Other climatic and hydrologic indices, including stream discharge during low-flow months, do not display statistically significant trends. Consideration of potential specific causal mechanisms driven by rising temperatures suggests that melting of permafrost and falling water tables (from decreased recharge) are probable explanations for the increasing concentrations. The prospect of future widespread increases in dissolved solutes from mineralized watersheds is concerning given likely negative impacts on downstream ecosystems and water resources, and complications created for the establishment of attainable remediation objectives at mine sites.     

Individual differences and a spatial learning factor in two strains of mice (Mus musculus).

Current theoretical approaches to animal intelligence either in the form of adaptive specializations or general processes make no explicit predictions nor do they provide substantial evidence concerning individual differences in problem solving. Two strains of mice (Mus musculus) were run through a battery of water escape tasks consisting of 4 spatial learning tasks, a visual discrimination task, and an activity control. The 2 strains were the second filial generation (F2) from a cross between C57BL/6 and DBA/2Js inbred strains and a CD-1 outbred strain. Results indicated positive correlations across all learning tasks in both strains for latency and error measures. Factor analysis revealed a significant first factor for these measures in both strains. These results suggest that at least some spatial and visual tasks in mice under this motivational condition share common properties. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Viscoelastic properties and structure of poly(acrylonitrile‐co‐methacrylic acid) polymer solutions for gel spinning at long aging times

The objective of the research is to obtain a more complete understanding of how aging affects the viscoelastic properties of polymer solutions to be used as starting materials for gel spinning of polymer fibers. Specifically, poly(acrylonitrile‐co‐methacrylic acid) solutions were prepared and characterized using rheological measurements and nuclear magnetic resonance spectroscopy. The results indicate that elastic character increased with increasing polymer concentration and that gelation of these solutions continued up to aging times of several weeks. Additionally, comparing the results from the two characterization methods show that while gelation continues to occur, the viscoelastic properties decrease after a critical time point suggesting that a chemical change occurs in the solutions at long times. However, these changes impact the solution dynamics minimally as the effective network properties were similar at the aging times studied here, but considerations for long‐term storage of polymer solutions for gel spinning are warranted. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39821.     

Covalently linking poly(lactic-co-glycolic acid) nanoparticles to microbubbles before intravenous injection improves their ultrasound-targeted delivery to skeletal muscle

Intravenously injected nanoparticles can be delivered to skeletal muscle through capillary pores created by the activation of microbubbles with ultrasound; however, strategies that utilize coinjections of free microbubbles and nanoparticles are limited by nanoparticle dilution in the bloodstream. Here, improvement in the delivery of fluorescently labeled ≈150 nm poly(lactic-co-glycolic acid) nanoparticles to skeletal muscle is attempted by covalently linking them to albumin-shelled microbubbles in a composite agent formulation. Studies are performed using an experimental model of peripheral arterial disease, wherein the right and left femoral arteries of BalbC mice are surgically ligated. Four days after arterial ligation, composite agents, coinjected microbubbles and nanoparticles, or nanoparticles alone are administered intravenously and 1 MHz pulsed ultrasound was applied to the left hindlimb. Nanoparticle delivery was assessed at 0, 1, 4, and 24 h post-treatment by fluorescence-mediated tomography. Within the coinjection group, both microbubbles and ultrasound are found to be required for nanoparticle delivery to skeletal muscle. Within the composite agent group, nanoparticle delivery is found to be enhanced 8- to 18-fold over 'no ultrasound' controls, depending on the time of measurement. A maximum of 7.2% of the initial nanoparticle dose per gram of tissue was delivered at 1 hr in the composite agent group, which was significantly greater than in the coinjection group (3.6%). It is concluded that covalently linking 150 nm-diameter poly(lactic-co-glycolic acid) nanoparticles to microbubbles before intravenous injection does improve their delivery to skeletal muscle.     

Anthropocene streams and base-level controls from historic dams in the unglaciated mid-Atlantic region, USA

Recently, widespread valley-bottom damming for water power was identified as a primary control on valley sedimentation in the mid-Atlantic US during the late seventeenth to early twentieth century. The timing of damming coincided with that of accelerated upland erosion during post-European settlement land-use change. In this paper, we examine the impact of local drops in base level on incision into historic reservoir sediment as thousands of ageing dams breach. Analysis of lidar and field data indicates that historic milldam building led to local base-level rises of 2-5 m (typical milldam height) and reduced valley slopes by half. Subsequent base-level fall with dam breaching led to an approximate doubling in slope, a significant base-level forcing. Case studies in forested, rural as well as agricultural and urban areas demonstrate that a breached dam can lead to stream incision, bank erosion and increased loads of suspended sediment, even with no change in land use. After dam breaching, key predictors of stream bank erosion include number of years since dam breach, proximity to a dam and dam height. One implication of this work is that conceptual models linking channel condition and sediment yield exclusively with modern upland land use are incomplete for valleys impacted by milldams. With no equivalent in the Holocene or late Pleistocene sedimentary record, modern incised stream-channel forms in the mid-Atlantic region represent a transient response to both base-level forcing and major changes in land use beginning centuries ago. Similar channel forms might also exist in other locales where historic milling was prevalent.     

The comparative effectiveness of cognitive processing therapy for male veterans treated in a VHA posttraumatic stress disorder residential rehabilitation program.

Objective: To examine the effectiveness of group cognitive processing therapy (CPT) relative to trauma-focused group treatment as usual (TAU) in the context of a Veterans Health Administration (VHA) posttraumatic stress disorder (PTSD) residential rehabilitation program. Method: Participants were 2 cohorts of male patients in the same program treated with either CPT (n = 104) or TAU (n = 93; prior to the implementation of CPT). Cohorts were compared on changes from pre- to posttreatment using the PTSD Checklist (PCL; Weathers, Litz, Herman, Huska, & Keane, 1993) and other measures of symptoms and functioning. Minorities represented 41% of the sample, and the mean age was 52 years (SD = 9.22). The CPT group was significantly younger and less likely to receive disability benefits for PTSD; however, these variables were not related to outcome. Results: Analyses of covariance controlling for intake symptom levels and cohort differences revealed that CPT participants evidenced more symptom improvement at discharge than TAU participants on the PCL, F(3, 193) = 15.32, p     

Effect of different antioxidants on lycopene degradation in oil‐in‐water emulsions

There is interest in incorporating lycopene into foods because it is a natural pigment and can also play a role in preventing disease. Therefore, the effect of the addition of various antioxidants in lycopene containing oil‐in‐water emulsions stabilized with Tween 20 at acidic pH was studied in order to determine protection systems against lycopene oxidation. In this model, EDTA showed pro‐oxidant activity while other chelators like citric acid and tripolyphosphate showed no effect. The free radical scavengers, propyl gallate (PG), gallic acid (GA), and α‐tocopherol all had the ability to decrease lycopene oxidation with α‐tocopherol being the most effective. The combination of 1 µM α‐tocopherol and 10 µM GA was more effective than the individual antioxidants. Addition of ascorbic acid to the combination of α‐tocopherol and GA system accelerated lycopene loss. These results suggest that by the proper selection of free radical scavenging antioxidants, lycopene stability in oil‐in‐water emulsions could be significantly improved. Practical applications: Evidence that dietary lycopene decreases the risk for a number of health conditions has generated new opportunities for addition of lycopene to functional foods. A successful strategy to deliver lycopene into foods is by means of oil‐in‐water emulsions. However, lycopene may decompose thus causing nutritional loss and color fading. In order to prevent this, the effectiveness of various antioxidants and their combinations in Tween 20 stabilized oil‐in‐water emulsions was studied. Overall, lycopene oxidation in oil‐in‐water emulsions could be significantly reduced by the proper selection of free radical scavengers. This fact is of interest to food industry for increasing the shelf‐life of lycopene containing functional foods where the lycopene is dispersed in the food in the form of an oil‐in‐water emulsion.     

Effects of Cooling Rate on Precipitate Evolution and Residual Stresses in Al–Si–Mn–Mg Casting Alloy

The residual stresses with different heat treatment conditions have been measured and correlated with the microstructural behavior of AA365. 30 and 100 K/min cooling of AA365 inhibited the transformation of precipitates under 773 K, respectively. The alloy cooled at 30 and 100 K/min exhibited tensile residual stresses of 6.2 and 5.4 MPa, respectively, while the alloy cooled at 1 and 10 K/min showed compressive stresses of ??12.8 and ??10.3 MPa, respectively. The formation β′, β″, and other intermetallic compounds affected the compressive residual stresses, and that the fracture of the brittle intermetallic phases could reduce the extent of residual stresses in the lattice through plastic deformation.     

The Duality of Caspases in Cancer,as Told through the Fly

Caspases, a family of cysteine-aspartic proteases, have an established role as critical components in the activation and initiation of apoptosis. Alongside this a variety of non-apoptotic caspase functions in proliferation, differentiation, cellular plasticity and cell migration have been reported. The activity level and context are important factors in determining caspase function. As a consequence of their critical role in apoptosis and beyond, caspases are uniquely situated to have pathological roles, including in cancer. Altered caspase function is a common trait in a variety of cancers, with apoptotic evasion defined as a “hallmark of cancer”. However, the role that caspases play in cancer is much more complex, acting both to prevent and to promote tumourigenesis. This review focuses on the major findings in Drosophila on the dual role of caspases in tumourigenesis. This has major implications for cancer treatments, including chemotherapy and radiotherapy, with the activation of apoptosis being the end goal. However, such treatments may inadvertently have adverse effects on promoting tumour progression and acerbating the cancer. A comprehensive understanding of the dual role of caspases will aid in the development of successful cancer therapeutic approaches.