Negative Friction and Lateral Loading on Piles

An example is first given of a structure founded on piles and having suffered damages caused by negative friction and passive lateral loading on the supporting piles. It appears that the effects of negative friction are in general less disastrous than should be expected from a simplified theoretical approach. The described case shows that, at the contrary, the passive lateral loadings, when not accounted for, become rapidly detrimental. Both influences are time delayed, with the consequence that the critical situation does mostly not occur during construction, but a certain time after completion. The design of a second structure, in which the passive lateral loading and negative friction on the piles were taken into account, and whose construction was successful, illustrated that the passive lateral loading is usually a much more determining factor than the negative friction and even every now and then than the dead and live loads

A (3+1) resonance enhanced multiphoton ionization study of the C 1S+ and E 1P states of CO: polarization dependence used to probe electronic excitation routes and electronic character

The three-photon excitations of the C 1 + and E 1 states have been investigated with resonance enhanced multiphoton ionization spectroscopy as a function of the polarization of the excitation light. From the observed polarization dependence the contributions of the various excitation routes have been determined, and the electronic character of these states has been analyzed. The results indicate that the v=0 and 1 vibrational levels of the E 1 state have slightly different electronic characters. The Journal of Chemical Physics is copyrighted by The American Institute of Physics

#Feesmustfall and beyond: Towards a sustainable national student loan regulatory framework

Universities have been forced to raise higher education fees with above inflation rates due to increasing operating costs and higher student numbers and decreasing real term government funding. While free higher education or other alternative funding models are being considered, the higher education sector is at stake: a sector that plays a vital role in creating improved lives for all South Africans. A sustainable framework is desperately required or universities will once again need to increase student fees at unreasonable rates to maintain quality. We therefore performed a mixed method documentary analysis to prove that fee-free higher education is not viable in South Africa as significant funds will either need to be reallocated from other sectors that also require funding, or it will have to be collected from already overburdened tax payers. The present study also developed a viable student fee regulatory framework with the use of grounded theory: subsidised higher education with the effective use of the already implemented National Student Financial Aid Scheme

Preparation and Friction Force Microscopy Measurements of Immiscible, Opposing Polymer Brushes

Solvated polymer brushes are well known to lubricate high-pressure contacts, because they can sustain a positive normal load while maintaining low friction at the interface. Nevertheless, these systems can be sensitive to wear due to interdigitation of the opposing brushes. In a recent publication, we have shown via molecular dynamics simulations and atomic force microscopy experiments, that using an immiscible polymer brush system terminating the substrate and the slider surfaces, respectively, can eliminate such interdigitation. As a consequence, wear in the contacts is reduced. Moreover, the friction force is two orders of magnitude lower compared to traditional miscible polymer brush systems. This newly proposed system therefore holds great potential for application in industry. Here, the methodology to construct an immiscible polymer brush system of two different brushes each solvated by their own preferred solvent is presented. The procedure how to graft poly(Nisopropylacrylamide) (PNIPAM) from a flat surface and poly(methyl methacrylate) (PMMA) from an atomic force microscopy (AFM) colloidal probe is described. PNIPAM is solvated in water and PMMA in acetophenone. Via friction force AFM measurements, it is shown that the friction for this system is indeed reduced by two orders of magnitude compared to the miscible system of PMMA on PMMA solvated in acetophenone

Changes in the Phenolic Composition and Antioxidant Activity of Pinotage, Cabernet Sauvignon, Chardonnay and Chenin blanc Wines During Bottle Ageing

The effect of bottle ageing on the antioxidant activity of Pinotage, Cabernet Sauvignon, Chardonnay and Chenin blanc wines, using the 2,2'-azino-di-(3-ethylbenzothialozine-sulphonic acid) radical cation (ABTS•+) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH0) scavenging assays, was determined. Storage at 0°C, 15°C or 30°C for a period of 12 months resulted in a significant (p ≤ 0.05) decrease in both the total antioxidant activity (TAAAnTs and TAAoPPH) and the total phenol content of the wines. The antioxidant potency of the total phenols of most of the wines, which is a ratio of antioxidant activity to the total phenol content, also decreased. The total anthocyanins in the red wines decreased significantly (p ≤ 0.05) over 12 months except for storage at 0°C, while the flavanol content of the Pinotage, Cabernet Sauvignon and Chardonnay wines increased up to nine months storage with a subsequent decrease to 12 months. The flavonol content of all the wines decreased, while only minor changes in their hydroxycinnamate content were observed during the storage period. Understanding the complexity of these reactions may provide clues for stabilising especially red wines to preserve the antioxidant activity without losing the beneficial effects of colouring and flavour development during bottle ageing

Maceration Before and During Fermentation: Effect on Pinotage Wine Phenolic Composition, Total Antioxidant Capacity and Objective Colour Parameters

Low-temperature maceration treatments (1, 2 and 4 days at 10 and 15°C) before fermentation and juice/skin mixing treatments (punching-down, pumping-over and rotor action every hour and every 3 hours) duringfermentation were investigated in terms of their effects on Pinotage wine phenolic composition, total antioxidant capacity (TAC) and colour over three vintages (2000 to 2002). Results for pre-fermentation maceration were notconsistent between vintages. Very few significant differences in the phenolic content, TAC and objective colour parameters were observed between the control wines and wines subjected to different pre-fermentation macerationtreatments. Pre-fermentation maceration, especially at 15°C, resulted in wines with increased vitisin A content.  Improvement of wine quality when using pre-fermentation maceration treatments at 10°C was noted previously, while no detrimental effect on the wine TAC was observed. The pumping-over treatment yielded wines with lower TAC and phenol content, as well as less favourable objective colour values, indicating that the punching-down or rotor treatment would be preferred. Although mixing at hourly intervals yielded a higher content of some phenolic compounds compared to the 3-hour interval mixing, mixing frequency did not affect the TAC of the wine. The objective colour parameters, h* and b*, were slightly lower at the higher mixing frequency in 2002 indicating a shift in the direction of a magenta hue