Polyvinyl alcohol (PVA) is a synthetic polymer derived from polyvinyl acetate through partial or full hydroxylation. PVA is commonly used in medical devices due to its low protein adsorption characteristics, biocompatibility, high water solubility, and chemical resistance. Some of the most common medical uses of PVA are in soft contact lenses, eye drops, embolization particles, tissue adhesion barriers, and as artificial cartilage and meniscus. The purpose of this review is to evaluate the available published information on PVA with respect to its safety as a medical device implant material for cartilage replacement. The review includes historical clinical use of PVA in orthopedics, and in vitro and in vivo biocompatibility studies. Finally, the safety recommendation involving the further development of PVA cryogels for cartilage replacement is addressed.

We present the current status of RADDOSE-3D, a software tool allowing the estimation of the dose absorbed in a macromolecular crystallography diffraction experiment. The code allows a temporal and spatial dose contour map to be calculated for a crystal of any geometry and size as it is rotated in an X-ray beam, and gives several summary dose values: among them diffraction weighted dose. This allows experimenters to plan data collections which will minimize radiation damage effects by spreading the absorbed dose more homogeneously, and thus to optimize the use of their crystals. It also allows quantitative comparisons between different radiation damage studies, giving a universal "x-axis" against which to plot various metrics.

No abstract

An amine-containing diacetylenic amphiphile was prepared from pentacosa-10,12-diynoic acid. Its monolayer properties as a floating Langmuir film were investigated. As a classic long chain amphiphile, condensed monolayers of pentacosa-10,12-diynylamine exhibited high collapse pressures and a solid-like character stable against compressive creep. A limiting molecular area of 23 A* 12/molecule was found, consistent with other single chain diacetylenic amphiphiles. Isothermal compression studies showed a distinct transition in monolayer organization from a disordered to an ordered or solid film below a molecular area of 25 A2/molecule. The nature of the film behavior at molecular areas greater than the transition to the solid could be manipulated by adjusting the subphase pH and/or the dissolved anion.

No abstract

The dimer, trimer, and tetramer of 1,11-dodecadiyne, HCC(CH2)8CCH, were synthesized. The solid-state polymerization of the dimer was investigated by infrared (IR) spectroscopy. IR bands due to the diacetylene moiety were identified through the comparison of the IR spectra of the dimer, trimer, and tetramer. The dimer was found to have two polymorphs, melt-crystallized and solution-crystallized. Both of the polymorphs undergo solid-state polymerization by exposure to gamma-ray or UV irradiation. The former has higher polymerizability for the diacetylene moiety than the latter. The solid-state polymerization of the terminal acetylene group was not observed. It is shown that the previously reported dimer structure in which both the diacetylene and terminal acetylene groups are polymerized to form an inherently electrically conducting polymer is incorrect

Much progress has been made over the last 15 years in characterising radiation damage (RD) to macromolecular crystals during 100 K X-ray diffraction experiments [1], and to a lesser extent, for those irradiated at room temperature (RT). Despite a now extensive body of literature on various aspects of RD in MX and SAXS (e.g.