Highly Efficient Method for Solvent-Free Synthesis of Diarylmethane and Triarylmethane from Benzylic Alcohols Using P2O5/Al2O3 or P2O5/SiO2 at Room Temperature

A highly efficient procedure for the synthesis of triarylmethane and diarylmethane via benzylation of aromatic hydrocarbons from benzyl alcohols using supported P2O5 on SiO2 and/or Al2O3 under solvent-free conditions is described. Excellent yields of triarylmethane and diarylmethane were obtained using P2O5-SiO2 (50% W/W) and/or P2O5-Al2O3 (50% W/W) at room temperature. The reusability of both supported P2O5 on SiO2 and Al2O3 were examined. Both supported reagents show favorable activities in first and second runs, however, a decline in reactivity was observed in following attempts. The reaction is scalable to >0.03 mole amounts.Keywords: Diarylmethane, triarylmethane, aromatic alcohol, P2O5, silica gel, alumin

Fungal Populations in Air and Materials in a Flood Simulation Study

Air quality was measured in a building subjected to flooding conditions analogous to that which occurred during Hurricane Katrina. This building was flooded to a depth of 0.61 m above the floor with pond water and maintained at that level for 3 wk. After the floodwater was drained, the building remained closed for an additional 3 wk. Immediately on opening, air samples were obtained and analyzed for fungal spores. Dry and wet material components of the building wall were analyzed for the presence of mold fungi by both culture and molecular techniques. Additional air samples were taken after a 30-da drying period and then after remediation of the building. The air measurements demonstrated the presence of high concentrations of indoor mold spores when the building was initially entered. Aspergillus/Penicillium were the dominate air molds. Fiberglass batt insulation supported the greatest concentration of culturable fungi, compared with other wall materials, followed by the paper facings of gypsum board and plywood sheathing. The solid wood stud, vinyl siding, and house wrap all supported low concentrations of culturable mold. After drying, the spore air contamination diminished more than 10-fold and the species of fungi on the materials drastically changed. After remediation, the spores inside the structure nearly matched those outside with respect to type and concentration

Immersed boundary-finite element model of fluid-structure interaction in the aortic root

It has long been recognized that aortic root elasticity helps to ensure efficient aortic valve closure, but our understanding of the functional importance of the elasticity and geometry of the aortic root continues to evolve as increasingly detailed in vivo imaging data become available. Herein, we describe fluid-structure interaction models of the aortic root, including the aortic valve leaflets, the sinuses of Valsalva, the aortic annulus, and the sinotubular junction, that employ a version of Peskin's immersed boundary (IB) method with a finite element (FE) description of the structural elasticity. We develop both an idealized model of the root with three-fold symmetry of the aortic sinuses and valve leaflets, and a more realistic model that accounts for the differences in the sizes of the left, right, and noncoronary sinuses and corresponding valve cusps. As in earlier work, we use fiber-based models of the valve leaflets, but this study extends earlier IB models of the aortic root by employing incompressible hyperelastic models of the mechanics of the sinuses and ascending aorta using a constitutive law fit to experimental data from human aortic root tissue. In vivo pressure loading is accounted for by a backwards displacement method that determines the unloaded configurations of the root models. Our models yield realistic cardiac output at physiological pressures, with low transvalvular pressure differences during forward flow, minimal regurgitation during valve closure, and realistic pressure loads when the valve is closed during diastole. Further, results from high-resolution computations demonstrate that IB models of the aortic valve are able to produce essentially grid-converged dynamics at practical grid spacings for the high-Reynolds number flows of the aortic root

Simulation of the Three-Dimensional Hinge Flow Fields of a Bileaflet Mechanical Heart Valve Under Aortic Conditions

Thromboembolic complications of bileaflet mechanical heart valves (BMHV) are believed to be due to detrimental stresses imposed on blood elements by the hinge flows. Characterization of these flows is thus crucial to identify the underlying causes for complications. In this study, we conduct three-dimensional pulsatile flow simulations through the hinge of a BMHV under aortic conditions. Hinge and leaflet geometries are reconstructed from the Micro-Computed Tomography scans of a BMHV. Simulations are conducted using a Cartesian sharp-interface immersed-boundary methodology combined with a second-order accurate fractional-step method. Physiologic flow boundary conditions and leaflet motion are extracted from the Fluid–Structure Interaction simulations of the bulk of the flow through a BMHV. Calculations reveal the presence, throughout the cardiac cycle, of flow patterns known to be detrimental to blood elements. Flow fields are characterized by: (1) complex systolic flows, with rotating structures and slow reverse flow pattern, and (2) two strong diastolic leakage jets accompanied by fast reverse flow at the hinge bottom. Elevated shear stresses, up to 1920 dyn/cm2 during systole and 6115 dyn/cm2 during diastole, are reported. This study underscores the need to conduct three-dimensional simulations throughout the cardiac cycle to fully characterize the complexity and thromboembolic potential of the hinge flows

Numerical Investigation of the Performance of Three Hinge Designs of Bileaflet Mechanical Heart Valves

Thromboembolic complications (TECs) of bileaflet mechanical heart valves (BMHVs) are believed to be due to the nonphysiologic mechanical stresses imposed on blood elements by the hinge flows. Relating hinge flow features to design features is, therefore, essential to ultimately design BMHVs with lower TEC rates. This study aims at simulating the pulsatile three-dimensional hinge flows of three BMHVs and estimating the TEC potential associated with each hinge design. Hinge geometries are constructed from micro-computed tomography scans of BMHVs. Simulations are conducted using a Cartesian sharp-interface immersed-boundary methodology combined with a second-order accurate fractional-step method. Leaflet motion and flow boundary conditions are extracted from fluid–structure-interaction simulations of BMHV bulk flow. The numerical results are analyzed using a particle-tracking approach coupled with existing blood damage models. The gap width and, more importantly, the shape of the recess and leaflet are found to impact the flow distribution and TEC potential. Smooth, streamlined surfaces appear to be more favorable than sharp corners or sudden shape transitions. The developed framework will enable pragmatic and cost-efficient preclinical evaluation of BMHV prototypes prior to valve manufacturing. Application to a wide range of hinges with varying design parameters will eventually help in determining the optimal hinge design

National Outbreak of Acanthamoeba Keratitis Associated with Use of a Contact Lens Solution, United States

Premarket standardized testing for Acanthamoeba spp. is warranted

Effects of fines migration on well productivity during steady state production

Well clogging and productivity decline have been widely observed in oil, gas, and artesian wells producing reservoir fines. The phenomenon has been explained by the lifting, migration, and subsequent plugging of the pores by the fine particles, finally resulting in permeability decrease. This has been observed in numerous core flood tests and field cases. In this work, the new basic equations for the detachment of fine particles, their migration, and size exclusion, causing the rock permeability decline, have been derived. The analytical model, developed for the regime of steady-state production with the gradual accumulation of strained particles, exhibits the linear skin factor growth versus the amount of produced reservoir fines. The modeling data are in good agreement with the well production history. The model allows predicting well productivity decline due to fines production based on short-term production data.Abbas Zeinijahromi, Alexandre Vaz, Pavel Bedrikovetsky and Sara Borazjan

Splitting in systems of PDEs for two-phase multicomponent flow in porous media

Abstract not availableS. Borazjani, A.J. Roberts, P. Bedrikovetsk