Poly(vinyl acetate)–clay hybrids prepared via emulsion polymerization, assisted by a nonionic surfactant

Hybrid materials containing poly(vinyl acetate) and montmorillonite (MMT) were prepared using an one-batch emulsion polymerization recipe, assisted by a nonionic surfactant. To explain the results of our experiments, a thorough investigation of the specific interactions between the compounds was done, in the wet as well as the dried state of the end-products. In dispersion, polymer–surfactant interactions were found to be driven by hydrophobic coupling into superficial (mixt) admicelles. Another important finding is that the amount of clay used in the recipes and its relative concentration with respect to the other reaction partners influences drastically the morphological units in the end-products. For low [MMT], well-defined, spherical particles are formed. At the other extreme, for high [MMT], production of polymeric, water-swollen aggregates is favored. A small amount of reformed MMT tactoids was detected in all casted hybrid films, indicating that most of the inorganic is dispersed in the organic phase

Impact of a centralized osteoporosis coordinator on post-fracture osteoporosis management: a cluster randomized trial

SUMMARY: We conducted a cluster randomized trial evaluating the effect of a centralized coordinator who identifies and follows up with fracture patients and their primary care physicians about osteoporosis. Compared with controls, intervention patients were five times more likely to receive BMD testing and two times more likely to receive appropriate management. INTRODUCTION: To determine if a centralized coordinator who follows up with fracture patients and their primary care physicians by telephone and mail (intervention) will increase the proportion of patients who receive appropriate post-fracture osteoporosis management, compared to simple fall prevention advice (attention control). METHODS: A cluster randomized controlled trial was conducted in small community hospitals in the province of Ontario, Canada. Hospitals that treated between 60 and 340 fracture patients per year were eligible. Patients 40 years and older presenting with a low trauma fracture were identified from Emergency Department records and enrolled in the trial. The primary outcome was ‘appropriate’ management, defined as a normal bone mineral density (BMD) test or taking osteoporosis medications. RESULTS: Thirty-six hospitals were randomized to either intervention or control and 130 intervention and 137 control subjects completed the study. The mean age of participants was 65 ± 12 years and 69% were female. The intervention increased the proportion of patients who received appropriate management within 6 months of fracture; 45% in the intervention group compared with 26% in the control group (absolute difference of 19%; adjusted OR, 2.3; 95% CI, 1.3–4.1). The proportion who had a BMD test scheduled or performed was much higher with 57% of intervention patients compared with 21% of controls (absolute difference of 36%; adjusted OR, 4.8; 95% CI, 3.0–7.0). CONCLUSIONS: A centralized osteoporosis coordinator is effective in improving the quality of osteoporosis care in smaller communities that do not have on-site coordinators or direct access to osteoporosis specialists

A note on NSA’s Dual Counter Mode of encryption

Abstract. We show that both variants of the Dual Counter Mode of encryption (DCM) submitted for consideration as an AES mode of operation to NIST by M. Boyle and C. Salter of the NSA are insecure with respect to both secrecy and integrity in the face of chosen-plaintext attacks. We argue that DCM cannot be easily changed to satisfy its stated performance goal and be secure. Hence repairing DCM does not appear worthwhile.

Organic–inorganic hybrids made from polymerizable precursors

Organic–inorganic hybrid films were prepared based on a recipe using organoalkoxysilanes’ ability to create an inorganic network combined with polymer network formation via radical polymerization of the organic groups. The starting mixtures included different triethoxysilanes (RTES), where the organic substitute (R) was varied from methyl- (MeTES), phenyl- (PTES), octyl- (OTES) to vinyl- (VTES). Additionally, films prepared using methacryloxypropyltrimethoxysilane (MPTS) were also investigated. Most of the formulations were enriched with tetraisopropyl orthotitanate (TIP). Based on phase diagrams, the limits of the one-phase liquid regions were determined for the initial (RTES–ethanol–water) ternary mixtures. Non-linear modifications of the refractive indexes versus water concentration, as well as the measured conductivity changes indicate that these apparent homogeneous systems are nanostructured as microemulsions. Based on the results of combined microscale (atomic force microscopy (AFM)) and macroscale (wettability, thermal analysis) investigations, it was possible to observe the internal structure and to explain the measured properties of the final composite films. The high resistance against solvent attack is based on the regular, granular-like structure of the end products. Heating the films (at temperatures above the thermal degradation range for the incorporated organics) forces the inorganic structures to collapse and undergo phase transformations