Increased resistance to stress corrosion of aluminum alloys

Stress corrosion resistance is increased by distorting surface grain-boundary structure and by interrupting the corrosion and stress corrosion. The first is accomplished by machining or shot peening and the second by removal from and later reexposure to the corrosive environment

Ultracold homonuclear and heteronuclear collisions in metastable helium

Scattering and ionizing cross sections and rates are calculated for ultracold collisions between metastable helium atoms using a fully quantum-mechanical close-coupled formalism. Homonuclear collisions of the bosonic ${}^{4}$He$^{*} +{}^{4}$He$^{*}$ and fermionic ${}^{3}$He$^{*} + {}^{3}$He$^{*}$ systems, and heteronuclear collisions of the mixed ${}^{3}$He$^{*} +{}^{4}$He$^{*}$ system, are investigated over a temperature range 1 $\mu$K to 1 K. Carefully constructed Born-Oppenheimer molecular potentials are used to describe the electrostatic interaction between the colliding atoms, and complex optical potentials used to represent loss through ionization from the ${}^{1,3}\Sigma$ states. Magnetic spin-dipole mediated transitions from the ${}^{5}\Sigma$ state are included and results reported for spin-polarized and unpolarized systems. Comparisons are made with experimental results, previous semi-classical models, and a perturbed single channel model.Comment: 14 pages, 9 figure

Photoassociation spectra and the validity of the dipole approximation for weakly bound dimers

Photoassociation (PA) of ultracold metastable helium to the 2s2p manifold is theoretically investigated using a non-perturbative close-coupled treatment in which the laser coupling is evaluated without assuming the dipole approximation. The results are compared with our previous study [Cocks and Whittingham, Phys. Rev. A 80, 023417 (2009)] that makes use of the dipole approximation. The approximation is found to strongly affect the PA spectra because the photoassociated levels are weakly bound, and a similar impact is predicted to occur in other systems of a weakly bound nature. The inclusion or not of the approximation does not affect the resonance positions or widths, however significant differences are observed in the background of the spectra and the maximum laser intensity at which resonances are discernable. Couplings not satisfying the dipole selection rule |J-1| <= J' <= |J+1| do not lead to observable resonances.Comment: 5 pages, 2 figures; Minor textual revision

Study of the general mechanism of stress corrosion of aluminum alloys and development of techniques for its detection Quarterly report, 1 May - 31 Aug. 1968

Mechanism of stress corrosion cracking in aluminum alloys and techniques for detection of surface defect

Sintering Kinetics of Plasma-Sprayed Zirconia TBCs

A model of the sintering exhibited by EB-PVD TBCs, based on principles of free energy minimization, was recently published by Hutchinson et al. In the current paper, this approach is applied to sintering of plasma-sprayed TBCs and comparisons are made with experimental results. Predictions of through-thickness shrinkage and changing pore surface area are compared with experimental data obtained by dilatometry and BET analysis respectively. The sensitivity of the predictions to initial pore architecture and material properties are assessed. The model can be used to predict the evolution of contact area between overlying splats. This is in turn related to the through-thickness thermal conductivity, using a previously-developed analytical model

Study of the general mechanism of stress corrosion of aluminum alloys and development of techniques for its detection Quarterly report, 1 Dec. 1967 - 29 Feb. 1968

Stress corrosion of aluminum alloys and techniques for its detectio

Study of the general mechanism of stress corrosion of aluminum alloys and development of techniques for its detection Annual summary report, 2 Jun. 1967 - 1 Jun. 1968

Stress corrosion cracking of high strength aluminum alloys investigated by electrochemical, mechanical, and electron microscopic technique

A pilot study exploring public awareness and knowledge of right hemisphere communication disorder compared with aphasia and stroke in Northwest London, UK

No previously published research has investigated public awareness and knowledge of Right Hemisphere Communication Disorders (RHCD). In comparison, there are a handful of published studies that have investigated public awareness and knowledge of aphasia. The results of these studies indicate that awareness and knowledge is low but has marginally increased in recent years, due to international efforts to raise the public profile of the disorder. Aims: The current study investigated public awareness and knowledge of RHCD and compared it to that of aphasia. Information regarding awareness and knowledge of stroke was also determined for those participants who did not have awareness of RHCD or aphasia. Methods & Procedures: A face-to-face survey of 87 members of the public was undertaken in North West London, United Kingdom. Outcomes and Results: Of the 87 survey respondents, only 9.2% reported having heard of RHCD and 4.6% met the criteria for having basic knowledge of this disorder. In comparison, 32.2% of participants had heard of aphasia and 24% had basic knowledge about it. While the results show that fewer people were aware and had knowledge of RHCD compared to aphasia, this difference was not significant. Of those participants who had heard of neither disorder, all had heard of and the majority had knowledge of stroke. Conclusions: The findings suggested that awareness of RHCD amongst members of the public is low. It is suggested that in order to improve quality of services, funding and social re-integration following a right hemisphere stroke, raising public awareness and knowledge is necessary

Further evidence of response by leukaemia patients in remission to antigen(s) related to acute myelogenous leukaemia.

Fifteen patients with acute myelogenous leukaemia were studied to determine if their remission blood leucocytes could be stimulated into taking up [3H] thymidine after in vitro culture with their own cryo-preserved irradiated AML leukaemia cells. In 6/15 patients it was possible to show autologous recognition and equal recognition of their stored leukaemia cells, even when they had previously been maintained in in vitro proliferative cultures in liquid suspension and undergoing myeloid maturation for one week. After in vitro proliferative culture, 4 populations of leukaemia cells produced material in the supernatant media between 3 and 7 days capable of inducing [3H] thymidine uptake in autologous (2 pts, 5 supernatants) and allogeneic (2 pts, 2 supernatants) AML remission lymphocytes, but not in normal donor lymphocytes. The relevance of these observations to tumour-associated AML antigen is discussed

Household Livelihoods, Marketing And Resource Impacts* A Case Study Of Bark Products In Eastern Zimbabwe

An IES Working Paper.Markets for craft and medicinal products derived from the bark of three tree species were assessed in rural and urban areas of Zimbabwe. Bark crafts from Adansonia digitata (baobab) are widely sold in these regions. The number of sellers has increased since the 1980s and has remained relatively stable since then. Competition for local purchasers is provided by domestic and imported substitutes. Most baobab craft items are relatively bulky and the export market for them is largely limited to affluent travellers from South Africa. This is a relatively localized market. Seasonality in baobab craft production and sales is pronounced in the rural area. Prices are transparent and arbitrage appears to occur. This is not the case in the markets for the bark of Warburgia salutaris, which is used as a traditional medicine. There are relatively few sellers, prices do not exhibit regionally consistent patterns and this species appears to have become locally extinct. Bark of Berchemia discolor is not highly commercialised in this region; no sales of this bark were observed in the course of the study.Funding for the study was provided by Canadian International Development Agency (CIDA) through the Agro-forestry Southern Africa project and the World Wide Fund for Nature (WWF) People and Plants Initiativ