3D printing hybrid organometallic polymer‐based biomaterials via laser two‐photon polymerization

Materials with microscale structures are gaining increasing interest due to their range of technical and medical applications. Additive manufacturing approaches to such objects via laser two‐photon polymerization, also known as multiphoton fabrication, enable the creation of new materials with diverse and tunable properties. Here, we investigate the properties of 3D structures composed of organometallic polymers incorporating aluminium, titanium, vanadium and zirconium. The organometallic polymer‐based materials were analysed using a variety of techniques including SEM, energy‐dispersive X‐ray spectroscopy, X‐ray photoelectron spectroscopy analysis and contact angle measurements and their biocompatibility was tested in vitro. Cell viability and mode of death were determined by 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2H‐tetrazolium bromide (MTT) assay and acridine orange/ethidium bromide staining. Polymers incorporating Al, Ti and Zr supported cell adhesion and proliferation, and showed low toxicity in vitro, whereas the organometallic polymer incorporating V was shown to be cytotoxic. Inductively coupled plasma optical emission spectrometry suggested that leaching of the V from the organometallic polymer is the likely cause of this. The preparation of the organometallic polymers is straightforward and both simple 2D and complex 3D structures can be fabricated with ease. Resolution tests of the newly developed organometallic polymer incorporating Al show that suspended lines with widths down to 200 nm can be fabricated. We believe that the materials described in this work show promising properties for the development of objects with sub‐micron features for biomedical applications (e.g. biosensors, drug delivery devices, tissue scaffolds etc.). © 2019 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

A quick method for evaluating the thresholds of workpiece surface damage in machining

This paper proposes a Pendulum-Based Cutting Test (PBCT) methodology which allows quick cutting tests for surface integrity evaluation along with providing cutting energies associated with particular level of workpiece surface damage, this is backed by an unified cutting energy model that links damage level of machined surface with energy partition in the cutting area. PBCT method could rapidly define the energy transferred to the workpiece that incurs particular magnitude of surface damage without using conventional machine tools and monitor the cutting process while only limited amount of materials is required. A demonstration of the proposed method is presented for Inconel718.     

On the influence of gamma prime upon machining of advanced nickel based superalloy

Whilst gamma prime (γ′) phase is the strengthening phase in Ni-based superalloys its influence on machining has been seldom investigated. This paper reports for the first time on the effect of γ′ upon machining of Ni-based superalloys when cutting with parameters yielding different cutting temperature intervals which lead to strengthening/softening effects on the workpiece (sub)surface. In-depth XRD, SEM/FIB, EBSD analysis and unique micro-pillar testing in the workpiece superficial layers indicated that with the increase of γ′ fraction the grain plastic deformation significantly decreased, while specific cutting energy can switch from low to high values influenced by the real cutting temperature.     

Hydrogenation behavior on 30 nm vanadium thin films with two different adhesion conditions

The influence of a thin polycarbonate de-adhesion layer on the hydrogen concentration is studied on 30 nm vanadium films deposited on glass substrates, using electrochemical hydrogenography in an optical microscopy and scanning tunneling microscopy. It is shown that the optical reflection provides information about the de-adhesion morphology (buckles) while the optical transmission signal gives information about concentration and film thickness changes. Artificially patterned samples allow simultaneous studying adhered and de-adhered film parts, for similar mean concentrations. The optical data clearly show a different hydrogen behavior of the two parts. Data interpretation suggests higher local hydrogen content in the adhered film parts than for the detached films parts. Strong changes in the optical transmission of the adhered film parts can be attributed to strong morphological changes at the film surface. These changes are mainly attributed to grain sliding processes in the vanadium film.     

eGovernment in Victoria ‐ evolution of a resource centre

In 1995 the Victorian Government set an ambitious target to have all suitable government services online by the end of 2001. A knowledge management process was put in place to share government online learnings as they evolved. One of the outputs of this knowledge management process was the Government Online Resource Centre ‐ a web based repository made available to the Victorian Public Sector on the Victorian Government Intranet. This resource was subsequently published on the Internet in December 2000. In March 2002, the Victorian Government launched ‘Putting People at the Centre’ ‐ the Victorian Government's eGovernment vision. The Resource Centre was relaunched as the eGovernment Resource Centre. Governments and organisations worldwide are now actively seeking out this website to promote their eGovernment programmes.     

Numerical modeling and performance evaluation of multi-tubular sodium alanate hydride finned reactor

The optimization of the hydrogen loading process in a multi-tubular sodium alanate hydride reactor equipped with longitudinal fins is investigated numerically. The effect of the number, thickness and tip clearance of the fins on the hydrogen charging rate is assessed, so that the fin optimal geometric properties are determined by the compromise between the hydrogen loading rate and the fin contribution to the weight and the volume of the storage system. Simulation results have shown that the hydrogen loading rate corresponding to this optimized configuration is 41% greater than the case without fins if we suppose a perfect interconnectivity between the fin tips and the internal walls of the hydride tubes. Otherwise, the amount of stored hydrogen decreases drastically. The loading of hydrogen under high charging pressures results in higher hydrogen loading rates and there is an interaction between the geometric and operating parameters leading to the optimized amount of stored hydrogen.