Evaluation of biocompatible monomers as substitutes for TEGDMA in resin-based dental composites.

This works reports the synthesis and characterization of diallyl(5-(hydroxymethyl)-1,3-phenylene) dicarbonate (HMFBA) and 5-(hydroxymethyl)-1,3-phenylene bis(2-methylacrylate) (HMFBM) monomers and its evaluation as Bis-GMA eluents in the formulation of composite resins for dental use. The experimental materials formulated with HMFBA and HMFBM monomers presented flexural strength values similar to those of the control group formulated with Bis-GMA/TEGDMA. Regarding volumetric contraction percentage, the values obtained of experimental materials with HMFBA was 1.88% and for HMFBM was 4.15%, both lower than control resin (4.68%). In the case of double bond conversion, the resin formulated with HMFBA monomer exhibited a greater degree of conversion (87%). Besides, the DMA analyses proved that the values for Tg guarantee a good mechanical performance at body temperature. The new resins formulated with HMFBA and HMFBM monomers exhibit a cellular viability close to 100%, which indicates the absence of cytotoxicity towards fibroblastic cells.

Synthesis of an allyl carbonate monomer as alternative to TEGDMA in the formulation of dental composite resins.

Over the past years, significant effort has been dedicated to synthesizing low-shrinking formulations, however, development of dental composites with low volumetric shrinkage continues to be challenging. The purpose of this study was to synthesize a bisphenol allylic derivate (BPhADAC) and evaluate its inclusion in the formulation of a photopolymerizable dental composite resin, as a BisGMA diluent. Experimental (BisGMA/BPhADAC) and control (BisGMA/TEGDMA) photopolymerizable composites were prepared. Double bond conversion, polymerization kinetics, volumetric shrinkage, water sorption, solubility, and flexural properties were investigated. The experimental composite showed higher degree of conversion values, less volumetric shrinkage and less water sorption than the control composite (p < 0.05). In addition, flexural strength between the materials was found to be similar. The overall properties prove that the allylic monomer BPhADAC could be potentially useful in the formulation of low-shrinking dental composite resins.

Thermal diffusivity measurement of spherical gold nanofluids of different sizes/concentrations.

In recent times, nanofluids have been studied by their thermal properties due to their variety of applications that range from photothermal therapy and radiofrequency hyperthermia (which have proven their potential use as coadjutants in these medical treatments for cancer diseases) to next-generation thermo-fluids. In this work, photoacoustic spectroscopy for a specific study of thermal diffusivity, as a function of particle size and concentration, on colloidal water-based gold nanofluids is reported. Gold nanoparticles were synthetized in the presence of hydroquinone through a seed-mediated growth with homogenous sizes and shapes in a range of 16 to 125 nm. The optical response, size and morphology of these nanoparticles were characterized using ultraviolet-visible spectroscopy and transmission electron microscopy, respectively. Thermal characterizations show a decrease in the thermal diffusivity ratio as the nanoparticle size is increased and an enhancement in thermal diffusivity ratio as nanoparticle concentration is added into the nanofluids. Compared with other techniques in the literature such as thermal lens and hot wire method, this photoacoustic technique shows an advantage in terms of precision, and with a small amount of sample required (500 µl), this technique might be suitable for the thermal diffusivity measurement of nanofluids. It is also a promising alternative to classical techniques.

Myeloproliferative disorders and the hyperviscosity syndrome.

Myeloproliferative disorders and the serum hyperviscosity syndrome can rapidly manifest with emergent presentations. Hyperviscosity occurs from pathologic elevations of either the cellular or acellular (protein) fractions of the circulating blood. Classic hyperviscosity syndrome presents with the triad of bleeding diathesis, visual disturbances, and focal neurologic signs. Emergency medicine providers should be aware of these conditions and be prepared to rapidly initiate supportive and early definitive management, including plasma exchange and apharesis. Early consultation with a hematologist is essential to managing these complex patients.

Myeloproliferative disorders and the hyperviscosity syndrome.

Myeloproliferative disorders and the serum hyperviscosity syndrome can rapidly manifest with emergent presentations. Hyperviscosity occurs from pathologic elevations of either the cellular or acellular (protein) fractions of the circulating blood. Classic hyperviscosity syndrome presents with the triad of bleeding diathesis, visual disturbances and focal neurologic signs. Emergency medicine providers should be aware of these conditions and be prepared to rapidly initiate supportive and early definitive management, including plasma exchange and apharesis. Early consultation with a hematologist is essential to managing these complex patients.

Near-infrared spectroscopy-guided closed-loop resuscitation of hemorrhage.

BACKGROUND: Endpoint resuscitation has been suggested as a better means to resuscitate penetrating injury. We performed computer-controlled closed-loop resuscitation using invasive cardiac output (CO) or noninvasive skeletal muscle oxygen saturation (SkMusSO(2)) via near infrared spectroscopy (NIRS). METHODS: Conscious sheep received a 4.0-mm aortotomy and uncontrolled hemorrhage at t = 0 min (T0) while resuscitation started at T20 using lactated Ringer's solution. RESULTS: The aortotomy rapidly decreased the mean arterial pressure (MAP) to approximately 30 mm Hg and CO to 20% to 30% of baseline. The SkMusSO(2) endpoint group required only half as much fluid through 4 hours of resuscitation as the CO endpoint group (34.9 +/- 8.4 mL/kg vs. 63.1 +/- 9.4 mL/kg). CO and MAP were lower in the SkMusSO(2) group after T60. Mean infusion volumes were 180% and 100% of the bled volume collected at autopsy in the CO and SkMusSO(2) groups. Brain and muscle oxygenation and base excess were as high or higher in the CO endpoint group. CONCLUSION: Closed-loop resuscitation with either CO or SkMusSO(2) endpoints effectively performs fluid resuscitation of severe uncontrolled hemorrhagic shock. Limited resuscitation may achieve favorable clinical results with volumes less than recommended by Advanced Trauma Life Support guidelines.