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The aim of this study was to assess the effects of a series of different surface coated quantum dots (QDs) (organic, carboxylated [COOH] and amino [NH₂] polytethylene glycol [PEG]) on J774.A1 macrophage cell viability and to further determine which part of the QDs cause such toxicity. Cytotoxic examination (MTT assay and LDH release) showed organic QDs to induce significant cytotoxicity up to 48 h, even at a low particle concentration (20 nM), whilst both COOH and NH₂ (PEG) QDs caused reduced cell viability and cell membrane permeability after 24 and 48 h exposure at 80 nM. Subsequent analysis of the elements that constitute the QD core, core/shell and (organic QD) surface coating showed that the surface coating drives QD toxicity. Elemental analysis (ICP-AES) after 48 h, however, also observed a release of Cd from organic QDs. In conclusion, both the specific surface coating and core material can have a significant impact on QD toxicity.

The effects of surfactants on the dynamics and characteristics of plain and composite electroless nickel plating (ENP) are highlighted and discussed herein. An outline of the rudiments of surfactants and some underlying selection criteria is presented at the outset, before emphasis is laid on the salient benefits of introducing such external agents during the plating process. Evidence suggests that their influence on key coating characteristics such as the rate of deposition, structure, corrosion resistance, and the degree of second-phase particle incorporation into the nickel matrix is significant, and depending on the nature and concentration of surfactant employed, can be of immense value to the system.

Horizontal hourly and sub-hourly diffuse and beam irradiance are required for the estimation of global irradiance on a given tilted surface. This information is used by engineers and architects for various solar energy applications and also to calculate solar heat gain in buildings. Although horizontal global irradiance is a commonly measured parameter for many sites, horizontal diffuse irradiance is not so readily obtainable. For such sites that measure global irradiation alone a simple but reasonably accurate method is required to estimate diffuse irradiance from its global counterpart. The aim of this study is to evaluate the accuracies of estimation of diffuse irradiance by developing annual, seasonal and monthly regressions between sub-hourly diffuse-ratio and clearness-index. An error analysis has been undertaken to compare these regression models. Practicalapplications: Diffuse and beam components of global irradiation are required to accurately simulate solar heat gain in buildings. The UK Meteorological office keeps records of diffuse and global irradiances for 9 stations, but there are a further 84 stations that solely record global irradiance. Hence there is a need to estimate diffuse or beam irradiance for these sites. This paper presents an investigation into the uses of annual, seasonal and monthly regressions between diffuse and global horizontal sub-hourly solar irradiation. These regressions have proven to be a simple but reasonably accurate method of estimating diffuse irradiance from its global counterpart.

The influence of a surfactant on the composition of nickel-yttria stabilised zirconia (YSZ) cermet coatings, applied by electroless nickel plating technique was examined. The amphiphilic characteristics of anionic surfactant sodium dodecyl sulphate (SDS), was relied upon for enhanced dispersion of YSZ particles co-deposited for use as anodes in solid oxide fuel cell technology and potential heat absorbing layers in thermal barrier coatings. Optical microscopy was employed to study the correlation between the plating thickness, level of ceramic loading and SDS concentration while the effect of the surfactant and fineness of YSZ particles on the as-deposited coating's ceramic to metal ratio, was analysed using energy dispersive X-ray analysis (EDXA) characterisation technique.