CFD and statistical approach to optimize the average air velocity and air volume fraction in an inert-particles spouted-bed reactor (IPSBR) system.

Inert-particles spouted bed reactor (IPSBR) is characterized by intense mixing generated by the circular motion of the inert particles. The operating parameters play an important role in the performance of the IPSBR system, and therefore, parameter optimization is critical for the design and scale-up of this gas-liquid contact system. Computational fluid dynamics (CFD) provides detailed modeling of the system hydrodynamics, enabling the determination of the operating conditions that optimize the performance of this contact system. The present work optimizes the main IPSBR operating parameters, which include a feed-gas velocity in the range 0.5-1.5 m/s, orifice diameter in the range 0.001-0.005 m, gas head in the range 0.15-0.35 m, mixing-particle diameter in the range 0.009-0.0225 m, and mixing-particle to reactor volume fraction in the range 2.0-10.0 vol % (which represents 0.01-0.1 kg of mixing particles loading). The effects of these parameters on the average air velocity and average air volume fraction in the upper, middle, and conical regions of the reactor were studied. The specific distance for each region has been measured from the orifice point to be 50 mm for the conical region, 350 mm for the middle region and 550 mm for the upper rejoin. The selected factors were optimized to obtain the minimum air velocity distribution (maximum gas residence time) and the maximum air volume fraction (maximum interfacial area concentration) because these conditions will increase the gas holdup, the gas-liquid contact area, and the mass transfer coefficient among phases. Response surface methodology (RSM) was used to determine the optimum operating conditions. The regression analysis showed an excellent fit of the experimental data to a second-order polynomial model. The interaction between the process variables was evaluated using the obtained three-dimensional surface plots. The analysis revealed that under the optimized parameters of a feed-gas velocity of 1.5 m/s, orifice diameter of 0.001 m, gas head of 0.164 m, mixing-particle diameter of 0.0225 m, and mixing-particle loading of 0.02 kg, the minimum average air velocity and highest air volume fraction were observed throughout the reactor.

Novel genomic microsatellite markers for genetic population and diversity studies of tropical scalloped spiny lobster (Panulirus homarus) and their potential application in related Panulirus species.

Fourteen polymorphic microsatellites with perfect di-, tri-, and tetra-nucleotide repeats were identified for Panulirus homarus using Roche 454 whole-genome sequencing method. Microsatellites were efficiently co-amplified in four multiplexes and a singleplex, providing consistent and easily interpretable genotypes. The number of alleles per locus ranged from 2 to 11 with the observed and expected heterozygosity ranging between 0.000-0.532 and 0.031-0.836, respectively. A significant deviation from Hardy-Weinberg equilibrium was observed for majority of the loci, probably due to homozygote excess. Genetic linkage disequilibrium analysis between all the possible pairs of the loci showed significant departure from the null hypothesis in the loci pairs Pho-G11-Pho-G33 and Pho-G33-Pho-G57. High success in primer cross-species amplification of these microsatellite markers indicates their utility for genetic studies of different Panulirus species.

Use of the Haddon matrix as a tool for assessing risk factors for sharps injury in emergency departments in the United Arab Emirates.

We investigated the epidemiology and prevention of sharps injuries in the United Arab Emirates. Among 82 emergency nurses and 38 doctors who responded to our questionnaire, risk factors for sharp device injuries identified using the Haddon matrix included personal factors (for the pre-event phase, a lack of infection control training, a lack of immunization, and recapping needles, and for the postevent phase, underreporting of sharps injuries) and equipment-related factors (for the pre-event phase, failure to use safe devices; for the event phase, failure to use gloves in all appropriate situations). Nearly all injuries to doctors were caused by suture needles, and among nurses more than 50% of injuries were caused by hollow-bore needles.