Novel Osteogenic Ti-6Al-4V Device For Restoration Of Dental Function In Patients With Large Bone Deficiencies: Design, Development And Implementation.

Custom devices supporting bone regeneration and implant placement are needed for edentulous patients with large mandibular deficiencies where endosteal implantation is not possible. We developed a novel subperiosteal titanium-aluminum-vanadium bone onlay device produced by additive manufacturing (AM) and post-fabrication osteogenic micro-/nano-scale surface texture modification. Human osteoblasts produced osteogenic and angiogenic factors when grown on laser-sintered nano-/micro-textured surfaces compared to smooth surfaces. Surface-processed constructs caused higher bone-to-implant contact, vertical bone growth into disk pores (microCT and histomorphometry), and mechanical pull-out force at 5 and 10 w on rat calvaria compared to non surface-modified constructs, even when pre-treating the bone to stimulate osteogenesis. Surface-modified wrap-implants placed around rabbit tibias osseointegrated by 6 w. Finally, patient-specific constructs designed to support dental implants produced via AM and surface-processing were implanted on edentulous mandibular bone. 3 and 8 month post-operative images showed new bone formation and osseointegration of the device and indicated stability of the dental implants.

Development of a blood urea monitoring system for the closed loop control of dialysis.

Optimal hemodialysis prescription through real-time blood urea (BU) monitoring and closed loop control of urea removal would be of significant clinical value. Progress toward a bedside BU analyzer and a control system is described here. An Amicon Minifilter inserted into the arterial bloodline provides a 1 ml/min stream of protein free ultrafiltrate for analysis. In vitro tests with bovine blood have shown excellent correlation between plasma (CP) and ultrafiltrate (CU) urea levels: CP = 0.961CU + 0.071, (n = 34, r = 0.998). In clinical hemodialysis studies, CU accurately represented the decay in CP. The BU analyzer uses a standard UV endpoint assay with a proportioning roller pump. The absorbance of the reacted mixture is read in a spectrophotometer after a 5 min incubation. For future control system design, the transfer function (TF) of the BU analyzer was measured using multifrequency binary testing. The data indicated that the analyzer may be modeled by a second order TF with a pure time delay. The same form of TF was also found to describe the Minifilter. Control of the removal rate of NaCl (substituted for urea) through automatic dialysate flow adjustment has been achieved with a simulated dialyzer-patient circuit (using a conductivity probe in place of the BU analyzer). A modified BU analyzer using computer controlled precision syringes for improved sample processing time and accuracy is also reported.

Codex Alimentarius: food quality and safety standards for international trade.

Since 1962, the Codex Alimentarius Commission (CAC) of the Food and Agriculture Organisation/World Health Organisation has been responsible for developing standards, guidelines and other recommendations on the quality and safety of food to protect the health of consumers and to ensure fair practices in food trade. The mission of the CAC remains relevant, but a number of factors have shown the need for new techniques to form the basis of food standards, the most important of which is risk analysis. The authors give a brief description of the role and work of the CAC and the efforts deployed by the Commission to respond to the challenges posed by new approaches to government regulation, harmonisation of national requirements based on international standards and the role of civil society.

Chemical vapour deposition synthetic diamond: materials, technology and applications.

Substantial developments have been achieved in the synthesis of chemical vapour deposition (CVD) diamond in recent years, providing engineers and designers with access to a large range of new diamond materials. CVD diamond has a number of outstanding material properties that can enable exceptional performance in applications as diverse as medical diagnostics, water treatment, radiation detection, high power electronics, consumer audio, magnetometry and novel lasers. Often the material is synthesized in planar form; however, non-planar geometries are also possible and enable a number of key applications. This paper reviews the material properties and characteristics of single crystal and polycrystalline CVD diamond, and how these can be utilized, focusing particularly on optics, electronics and electrochemistry. It also summarizes how CVD diamond can be tailored for specific applications, on the basis of the ability to synthesize a consistent and engineered high performance product.

Infrared properties of chemical-vapor deposition polycrystalline diamond windows.

Low-resolution transmittance and reflectance spectra of high-quality chemical-vapor deposition (CVD) diamond windows were measured in the infrared in the 2.5-500-mum wavelength range (20-4000 cm(-1)). High-resolution measurements on a window with nearly parallel surfaces show well defined interference fringes at low frequencies. By standard procedures the optical constants n and k of CVD diamond were determined, for the first time to the author's knowledge, in the far-infrared region. It is shown that a window with a large wedge angle, close to 1 degrees , does not produce appreciable interference fringes. Modeling of these results confirms that interference fringes can be avoided by use of properly wedged CVD diamond windows. This result is of considerable relevance to the use of CVD diamond windows in spectroscopic applications for which fringe suppression is a major requirement.