Life in the slip lane: the effect of molecular level friction on algal adhesion

The settlement and adhesion of Navicula perminuta and Ulva linza to methyl-terminated alkanethiol self-assembled monolayers (SAMs) of increasing chain length has been investigated. Organisms were allowed to settle onto the monolayers and were subsequently exposed to hydrodynamic shear stress in order to determine their adhesion strength. Results show that as the SAM structure changes from amorphous to crystalline (C14), there is a marked change in the adhesion of N. perminuta and U. linza. Given that the SAMs in the series all exhibit similar contact angle behaviour and surface energy, it is hypothesized that the lubricity of the surface plays a role in determining the surface adhesion

Measuring Costs and Outcomes of Tele-Intervention When Serving Families of Children who are Deaf/Hard-of-Hearing

Background: Optimal outcomes for children who are deaf/hard-of-hearing (DHH) depend on access to high quality, specialized early intervention services. Tele-intervention – the delivery of early intervention services via telehealth technology - has the potential to meet this need in a cost-effective manner.Method: Twenty-seven families of infants and toddlers with varying degrees of hearing loss participated in a randomized study, receiving their services primarily through TI or via traditional in-person home visits. Pre- and post-test measures of child outcomes, family and provider statisfaction, and costs were collected.Results: The TI group scored statistically significantly higher on the expressive language measure than the in-person group (p =.03). A measure of home visit quality revealed that the TI group scored statistically significantly better on the Parent Engagement subscale of the Home Visit Rating Scales-Adapted & Extended (HOVRS-A+; Roggman, et al., 2012). Cost savings associate with providing services via TI increased as the intensity of service delivery increased. Although most providers and families were positive about TI, there was great variability in their perceptions.Conclusions: Tele-intervention is a promising cost-effective method for delivering high quality early intervention services to families of children who are DHH

Improving the exchange and correlation potential in density-functional approximations through constraints

We review and expand on our work to impose constraints on the effective Kohn–Sham (KS) potential of local and semi-local density-functional approximations. Constraining the minimisation of the approximate total energy density-functional invariably leads to an optimised effective potential (OEP) equation, the solution of which yields the KS potential. We review briefly our previous work on this and demonstrate with numerous examples that despite the well-known mathematical issues of the OEP with finite basis sets, our OEP equations are numerically robust. We demonstrate that appropriately constraining the ‘screening charge’ which corresponds to the Hartree, exchange and correlation potential not only corrects its asymptotic behaviour but also allows the exchange and correlation potential to exhibit a non-zero derivative discontinuity, a feature of the exact KS potential that is necessary for the accurate prediction of band-gaps in solids but very hard to capture with semi-local approximations

Matchout deuterium labelling of proteins for small-angle neutron scattering studies using prokaryotic and eukaryotic expression systems and high cell-density cultures.

Small-angle neutron scattering (SANS) is a powerful technique for the characterisation of macromolecular structures and interactions. Its main advantage over other solution state approaches is the ability to use D2O/H2O solvent contrast variation to selectively match out specific parts of a multi-component system. While proteins, nucleic acids, and lipids are readily distinguished in this way, it is not possible to locate different parts of a protein-protein system without the introduction of additional contrast by selective deuteration. Here, we describe new methods by which 'matchout labelled' proteins can be produced using Escherichia coli and Pichia pastoris expression systems in high cell-density cultures. The method is designed to produce protein that has a scattering length density that is very close to that of 100% D2O, providing clear contrast when used with hydrogenated partner proteins in a complex. This allows the production of a single sample system for which SANS measurements at different solvent contrasts can be used to distinguish and model the hydrogenated component, the deuterated component, and the whole complex. The approach, which has significant cost advantages, has been extensively tested for both types of expression system