Evaluation of the mechanical behaviour of nanometre-thick coatings deposited using an atmospheric pressure plasma system

This study evaluated the use of pin-on-disc wear testing as a technique to examine the mechanical behaviour of nanometre thick plasma deposited coatings. The coatings were deposited onto polyethylene terephthalate and silicon wafer substrates by directly injecting an aerosol of siloxane liquid precursors into a helium/oxygen atmospheric pressure plasma. The siloxane precursors examined were hexamethyldisiloxane, polydimethylsiloxane and tetramethyldisiloxane. The mechanical performance of 21 (± 3) nm thick coatings was compared using a pin-on-disc wear test technique and fragmentation tests. An increase in the level of precursor plasma exposure was found to be associated with an increase in coating surface energy and a reduction in coating roughness and resulted in enhanced wear resistance. Fragmentation tests revealed a transition from ductile failure to brittle failure as the level of plasma exposure increased. This correlated with the reduction in coating wear rates. Wear track depth and proximity to the coating/substrate interface were both found to influence the rate or wear. A simple correlation between wear rate and applied force is presented as a method for comparing coating performance using pin-on-disc wear testing.     

Linear Regression and Adaptive Appearance Models for Fast Simultaneous Modelling and Tracking

This work proposes an approach to tracking by regression that uses no hard-coded models and no offline learning stage. The Linear Predictor (LP) tracker has been shown to be highly computationally efficient, resulting in fast tracking. Regression tracking techniques tend to require offline learning to learn suitable regression functions. This work removes the need for offline learning and therefore increases the applicability of the technique. The online-LP tracker can simply be seeded with an initial target location, akin to the ubiquitous Lucas-Kanade algorithm that tracks by registering an image template via minimisation.     

Studying protein–ligand interactions using protein crystallography

Protein X-ray crystallography is now a relatively high-throughput technique that plays a major role in structure-based drug design programs where the method of soaking small organic ligands into protein crystals is used to confirm or identify binding modes. In this review, we discuss some experimental approaches for ‘soaking-in’ ligands into protein crystals where the major problem is poor solubility of the ligand. We also provide examples showing how crystal soaking can be used as a technique for establishing ligand binding strength: K _c (the apparent ligand–protein dissociation constant in the crystal), which for some proteins at least, is found to be very similar to the solution K _d. Kinetic effects are also found to be important and the rate at which ligands soak into crystals is shown to vary by orders of magnitude from 10^?1 to 10⁷?s depending on the system.     

Low temperature aqueous precipitation of needle-like nanophase hydroxyapatite

The use of tissue engineered biodegradable porous scaffolds has become an important focus of the biomedical research field. The precursor materials used to form these structures play a vital role in their overall performance thus making the study and synthesis of these selected materials imperative. The authors present a comparison and characterisation of hydroxyapatite (HA), a popular calcium phosphate (CaP) biomaterial, synthesised by an aqueous precipitation (AP) method. The influence of various reaction conditions on the phase, crystallinity, particle size as well as morphology, molecular structure, potential in-vivo bioactivity and cell viability were assessed by XRD, SEM and TEM, FTIR, a simulated body fluid (SBF) test and a live/dead assay using MC3T3 osteoblast precursor cells, respectively. Naturally carbonated nanoparticles of HA with typically needle-like morphology were synthesised by the reported AP method. Initial pH was found to influence the crystallisation process and determine the CaP phase formed as well as the resultant particle and crystallite sizes. A marked change in particle morphology was also observed above pH 9. The use of toluene as a replacement solvent for water up to 60 % was found to reduce the crystallinity of as-synthesised HA. This has marked influence on the effect of ethanolamine (5 wt%), which was found to improve HA crystallinity. SEM and EDS were used to confirm the growth of carbonated apatite on the surface of HA pellets immersed in SBF for up to 28 days. Cell culture results revealed viable cells on all samples where pH was controlled and maintained at 10–11 during precipitation, including those that used ethanolamine and toluene in preparation. When the initial alkali pH was not maintained non-viable cells were observed on HA substrates.     

Quantifying the limits of CAR T-cell delivery in mice and men

CAR (Chimeric Antigen Receptor) T cells have demonstrated clinical success for the treatment of multiple lymphomas and leukaemias, but not for various solid tumours, despite promising data from murine models. Lower effective CAR T-cell delivery rates to human solid tumours compared to haematological malignancies in humans and solid tumours in mice might partially explain these divergent outcomes. We used anatomical and physiological data for human and rodent circulatory systems to calculate the typical perfusion of healthy and tumour tissues, and estimated the upper limits of immune cell delivery rates across different organs, tumour types and species. Estimated maximum delivery rates were up to 10 000-fold greater in mice than humans yet reported CAR T-cell doses are typically only 10–100-fold lower in mice, suggesting that the effective delivery rates of CAR T cells into tumours in clinical trials are far lower than in corresponding mouse models. Estimated delivery rates were found to be consistent with published positron emission tomography data. Results suggest that higher effective human doses may be needed to drive efficacy comparable to mouse solid tumour models, and that lower doses should be tested in mice. We posit that quantitation of species and organ-specific delivery and homing of engineered T cells will be key to unlocking their potential for solid tumours.     

清洁电力行动——由化石能源转向清洁能源

1电力行业的碳零排放之路燃烧煤、石油和天然气等化石燃料所排放的二氧化碳在大气层中不断积累,像毛毯一样包裹着地球,使热量聚集,导致全球气候变暖。很多证据表明,全球气候变化是目前人类所面临的波及范围最广的环境问题。它将对野生动植物栖息地、生物多样性、粮食供应、经济     

Rapid application design of an electronic clinical skills portfolio for undergraduate medical students

The aim was to find how to use information and communication technology to present the clinical skills content of an undergraduate medical curriculum. Rapid application design was used to develop the product, and technical action research was used to evaluate the development process. A clinician-educator, two medical students, two computing science masters students, two other project workers, and a hospital education informatics lead, formed a design team. A sample of stakeholders took part in requirements planning workshops and continued to advise the team throughout the project. A university hospital had many features that favoured fast, inexpensive, and successful system development: a clearly defined and readily accessible user group; location of the development process close to end-users; fast, informal communication; leadership by highly motivated and senior end-users; devolved authority and lack of any rigidly imposed management structure; cooperation of clinicians because the project drew on their clinical expertise to achieve scholastic goals; a culture of learning and involvement of highly motivated students. A detailed specification was developed through storyboarding, use case diagramming, and evolutionary prototyping. A very usable working product was developed within weeks. "SkillsBase" is a database web application using Microsoft Active Server Pages, served from a Microsoft Windows 2000 Server operating system running Internet Information Server 5.0. Graphing functionality is provided by the KavaChart applet. It presents the skills curriculum, provides a password-protected portfolio function, and offers training materials. The curriculum can be presented in several different ways to help students reflect on their objectives and progress towards achieving them. The reflective portfolio function is entirely private to each student user and allows them to document their progress in attaining skills, as judged by self, peer and tutor assessment, and examinations. Training materials include web links and materials developed locally using pedagogic principles developed by the SkillsBase team. Although the usability of SkillsBase has been proven, uptake of software that has arisen 'bottom-up' from within the curriculum has proved slow. We plan to incorporate the SkillsBase services into a more comprehensive virtual managed learning environment, anticipating that presenting the functionality in an environment that is routinely used by students and teachers will increase uptake and use.     

Dynamics of gravity dam-reservoir systems

The response of a long concrete gravity dam-reservoir system for a harmonic rigid base acceleration normal to the dam axis is investigated.The hydrodynamic pressure acting on the vertical wet surface of the dam is first evaluated in closed form as a function of the unknown deflections of the dam-reservoir interface and the ground acceleration. Employing finite element techniques, the motion of the dam is investigated. The hydrodynamic pressures enter the equation of motion of the dam as loadings in excess of the inertia load.In this approach, the general flexibility of the dam cross-section and the compressibility of water are taken into account. The viscosity of water and the effect of the surface waves are neglected.The coupling between the dam and the reservoir results in changes in the mass and stiffness properties of the dam which depend on the excitation frequency. For an excitation frequency greater than the fundamental frequency of the reservoir, the damping properties of the dam are also modified.