Surfaces are the primary place of contact between a biomaterial and its host organism. Typically, prostheses have to fulfil demanding structural and mechanical requirements, yet the material best for those functions may be bio-incompatible. Surface treatment or coating provides a means to overcome that problem, which means both integration within the host physiology and stabilization with respect to corrosion and wear. The adsorption of biomacromolecules is pivotal for biocompatibility. The impossibility of keeping proteins away from most implants means that very careful consideration has to be given to this aspect, and both prevention (for bloodstream implants) and promotion (for bone replacement and repair) occur with equal importance. This paper also considers the metrology of relevant physical and chemical aspects of surfaces.

Microsecond flash photolysis of solutions of uranyl salts in water, H3PO4, H2S04 and other media yields an intense, but short lived transient absorption spectrum in the region of 570 nm which exhibits vibronic structure with an average band separation of 580 cm-'. The decay of the transient in water was determined by laser flash photolysis to be first order with kl = 8.02 x lo5 s-I, but with a considerable isotope effect ( k l p , 0 ) = 4 . 2 0 ~ lo5 s-l). kl accords with the lifetime of the luminescence of aqueous UO;' ion determined by single photon counting (k, = 3.85 x loJ s-I). Both the 570 nm absorption and the emission (as determined by both single photon counting and conventional fluorimetry) are quenched on addition of various alcohols, the Stern-Volmer quenching constants closely correlating with the absolute quenching constants for the transient determined by laser flash photolysis. Large isotope effects were found for quenching by deuterated methanol, isopropanol and cyclohexanol both of the transient absorption and the emission. We conclude that the same electronic state of UOz+ is responsible for (i) emission to the ground state, (ii) the absorption at 570 nrn to a higher excited state and (iii) the photo-oxidation of aliphatic alcohols, principally by a process of abstraction of an H atom bonded to carbon from a -CH20H or =CHOH group.

No abstract

No abstract

This review provides a guide to researchers who wish to establish a biobank. It also gives practical advice to investigators seeking access to samples of healthy or diseased human hearts. We begin with a brief history of the Sydney Heart Bank (SHB) from when it began in 1989, including the pivotal role played by the late Victor Chang. We discuss our standard operating procedures for tissue collection which include cryopreservation and the quality assurance needed to maintain the long-term molecular and cellular integrity of the samples. The SHB now contains about 16,000 heart samples derived from over 450 patients who underwent isotopic heart transplant procedures and from over 100 healthy organ donors. These enable us to provide samples from a wide range of categories of heart failure. So far, we have delivered heart samples to more than 50 laboratories over two decades, and we answer their most frequently asked questions. Other SHB services include the development of tissue microarrays (TMA). These enable end users to perform preliminary examinations of the expression and localisation of target molecules in diseased or aging donor hearts, all in a single section of the TMA. Finally, the processes involved in managing tissue requests from external users and logistics considerations for the shipment of human tissue are discussed in detail.

This paper is based on the information gathered within the Multi-Material Micro-Manufacture (4M) Network activities in the Processing of Metals Division (Task 7.2 ‘Tooling’) ( www.4m-net.org ). The aim of the task involves a systematic analysis of the partners' expertise in different microtechnologies for processing tooling inserts made of metal. The following technologies have been analysed: micromilling, micro-electrodischarge machining (EDM, including wire-EDM, sinking-EDM, and EDM-milling), laser micromachining, electroforming, and electrochemical milling (ECF) (an electrochemical machining innovative process proposed by HSG-IMAT). Considered tool-insert materials are nickel for electroforming, stainless steel for ECF, and tool steel (AISI H13) for all other processes. Typical features (ribs, channels, pins, and holes) required by micro-optics, microfluidics, and sensor and actuator applications have been selected to form the benchmark part and to carry out this analysis. The results provide a global comparison between the micromanufacturing processes mentioned earlier in terms of technical capabilities and cost effectiveness of different feature machinings. As a second result, the current limitations of these technologies concerning feature sizes, surface finish, aspect ratios, etc. have been identified. The main conclusion drawn is the absence of a consolidated technology to produce three-dimensional free-form shapes smaller than 100–200 μm to date.

No abstract

No abstract