Compact Saloplastic Poly(Acrylic Acid)/Poly(Allylamine) Complexes: Kinetic Control Over Composition,Microstructure, and Mechanical Properties

Durable compact polyelectrolyte complexes (CoPECs) with controlled porosity and mechanical properties are prepared by ultracentrifugation. Because the starting materials, poly(allylamine hydrochloride) (PAH) and poly(acrylic acid sodium salt) (PAA), are weak acids/bases, both composition and morphology are controlled by solution pH. In addition, the nonequilibrium nature of polyelectrolyte complexation can be exploited to provide a range of compositions and porosities under the influence of polyelectrolyte addition order and speed, and concentration. Confocal microscopy shows these “saloplastic” materials to be highly porous, where pore formation is attributed to a combination of deswelling of the polyelectrolyte matrix and expansion of small inhomogenities by osmotic pressure. The porosity (15–70%) and the pore size (<5 μm to >70 μm) of these materials can be tuned by adjusting the PAA to PAH ratio, the salt concentration, and the pH. The modulus of these CoPECs depends on the ratio of the two polyelectrolytes, with stoichiometric complexes being the stiffest due to optimized charge pairing, which correlates with maximized crosslinking density. Mechanical properties, pore sizes, and pore density of these materials make them well suited to three dimensional supports for tissue engineering applications.     

Inkjet Printing of Amphotericin B onto Biodegradable Microneedles Using Piezoelectric Inkjet Printing

The delivery of amphotericin B, a pharmacologic agent with activity against a broad spectrum of fungi as well as against parasitic protozoa, has been complicated by the fact that amphotericin B exhibits poor solubility in aqueous solutions at physiologic pH levels. In this study, piezoelectric inkjet printing was used to modify the surfaces of Gantrez 169 BF microneedles (Ashland, Covington, KY). These amphotericin B-loaded microneedles demonstrated activity against Candida parapsilosis in a radial diffusion assay. The results of this study suggest that a combination of visible light dynamic mask microstereolithography, micromolding, and piezoelectric inkjet printing may be used to prepare amphotericin B-loaded microneedles with antifungal properties. It is envisioned that microneedles containing amphotericin B may be used for transdermal delivery of pharmacologic agents for the treatment of cutaneous fungal infections as well as cutaneous leishmaniasis.     

Contents of dietary fibre components and their relation to associated bioactive components in whole grain wheat samples from the HEALTHGRAIN diversity screen

A large and diverse material collection of whole grain wheat samples (n = 129) was analysed for total dietary fibre (TDF) content and composition, including fructan (11.5–15.5%). Correlations between the dietary fibre components, associated bioactive components (e.g. tocols, sterols, phenolic acids and folates) and agronomic properties previously determined on the same samples were found with multivariate analysis (PCA). Samples from the same countries had similar characteristics. The first PC described variation in components concentrated in the starchy endosperm (e.g. starch, β-glucan and fructan) and the dietary fibre components concentrated in the bran (e.g. TDF, arabinoxylan and cellulose). The second PC described the variation in kernel weight and other bran components such as alkylresorcinols, tocols and sterols. Interestingly, there was no correlation among these different groups of bran components, which reflected their concentration in different bran tissues. The results are of importance for plant breeders who wish to develop varieties with health-promoting effects.     

Daguerreotypes on copper

Abstract

The history of photography is dominated by accounts of various processes which utilize the light sensitivity of silver halides. It is less well known that cuprous halides are also light sensitive, and that they share with silver halides the ability to retain a latent image¹. It is helpful to review the history of light-sensitive processes based on cuprous halides before describing a new process for making daguerreotype-like images on copper.     

NEVA: Visual Analytics to Identify Fraudulent Networks

Trust-ability, reputation, security and quality are the main concerns for public and private financial institutions. To detect fraudulent behaviour, several techniques are applied pursuing different goals. For well-defined problems, analytical methods are applicable to examine the history of customer transactions. However, fraudulent behaviour is constantly changing, which results in ill-defined problems. Furthermore, analysing the behaviour of individual customers is not sufficient to detect more complex structures such as networks of fraudulent actors. We propose NEVA (Network dEtection with Visual Analytics), a Visual Analytics exploration environment to support the analysis of customer networks in order to reduce false-negative and false-positive alarms of frauds. Multiple coordinated views allow for exploring complex relations and dependencies of the data. A guidance-enriched component for network pattern generation, detection and filtering support exploring and analysing the relationships of nodes on different levels of complexity. In six expert interviews, we illustrate the applicability and usability of NEVA.     

An assessment of in vivo failures of alumina ceramic total hip joint replacements

Several cases of alumina ceramic hip replacement failures are reviewed fractographically. Three main findings are illustrated. Firstly, there is evidence that surgeons can damage the femoral head bore surface during surgery. Secondly, three of the failures described are of extended neck designs which are weaker than those of normal or short length in axial laboratory testing. Under physiological loading, such geometry can lead to levering forces, inappropriate localized contact with the metallic stem and stress concentrations. Delayed failure can ensue, with a fracture pattern quite different from that seen in conventional uniaxial testing. Thirdly, while some failures show head bore surfaces which are clean apart from metallic witness marking, others show brown stains and white deposits suggesting poor conformal contact. We suspect either stems become damaged during surgery before mounting the head or entrapment of debris, pointing to handling care and cleanliness varying between hospitals.