Performance Correlations for Reciprocating Plate Extraction Columns

Abstract The height equivalent to a theoretical stage (HETS) is estimated using one correlation to describe behavior for reciprocating speeds below the optimum point and a second expression to estimate HETS values for reciprocating speeds above it. These two equations are then combined to yield a generalized expression that is applicable in both regions and which can be used to predict the minimum HETS and the optimum reciprocating speed. The observed dependence on the operating parameters and the physical properties of the liquid/liquid system generally agree with those observed in HETS correlations for pulse columns.     

Synergistic Effect in Selective Reduction of NO by Alkanes over Mechanically Mixed Oxide Catalysts

The process of selective catalytic reduction of nitrogen oxides by propane in the presence of O₂, as well as in the presence or absence of CO, was studied over series of commercial oxide catalysts used in petrochemical processes. For the first time synergistic effect was observed for catalytic systems consisting of mechanical mixtures of Cu–Zn–Ni–Al (catalyst I) + Fe–Cr (catalyst II) and Cu–Zn–Ni–Al (catalyst I) + Ni–Cr (catalyst III). The activity of these mixtures in nitrogen oxides reduction by propane was greater than that of individual components in each case. The worked-out catalytical systems showed high effectivity in the process of simultaneous removal of several toxic components: NO _x , CO, hydrocarbons – from model gas mixtures, as well as from real exhausts of automotive transport.     

Gas sensing properties of nanocrystalline diamond films

Toxic gas sensing device with metal electrodes built into nanocrystalline diamond (NCD) is investigated. The NCD morphology is controlled via seeding and/or deposition time. The surface properties and morphology of NCD are studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). AFM measurements reveal increase in NCD surface area by up to 13%. Gas sensing properties of H-terminated NCD device show high sensitivity towards oxidizing species where the surface conductivity is increased by an order of magnitude for humid air and by three orders of magnitude for COCl₂. The surface conductivity exhibits a small decrease to reducing spices (CO₂, NH₃).     

CO tolerance and CO oxidation at Pt and Pt-Ru anode catalysts in fuel cell with polybenzimidazole-H3PO4 membrane

CO tolerance of H₂-air single cell with phosphoric acid doped polybenzidazole (PA-PBI) membrane was studied in the temperature range 140-180 °C using either dry or humidified fuel. Fuel composition was varied from neat hydrogen to 67% (vol.) H₂-33% CO mixtures. It was found that poisoning by CO of Pt/C and Pt-Ru/C hydrogen oxidation catalysts is mitigated by fuel humidification. Electrochemical hydrogen oxidation at Pt/C and Pt-Ru/C catalysts in the presence of up to 50% CO in dry or humidified H₂-CO mixtures was studied in a cell driven mode at 180 °C. High CO tolerance of Pt/C and Pt-Ru/C catalysts in FC with PA-PBI membrane at 180 °C can be ascribed to combined action of two factors—reduced energy of CO adsorption at high temperature and removal of adsorbed CO from the catalyst surface by oxidation. Rate of electrochemical CO oxidation at Pt/C and Pt-Ru/C catalysts was measured in a cell driven mode in the temperature range 120-180 °C. Electrochemical CO oxidation might proceed via one of the reaction paths—direct electrochemical CO oxidation and water-gas shift reaction at the catalyst surface followed by electrochemical hydrogen oxidation stage. Steady state CO oxidation at Pt-Ru/C catalyst was demonstrated using CO-air single cell with Pt-Ru/C anode. At 180 °C maximum CO-air single cell power density was 17 mW cm⁻² at cell voltage U = 0.18 V.     

Sensory Detection and Population Thresholds for Sodium Tripolyphosphate in Cooked Ground Turkey Patties

Sodium tripolyphosphate (STP) at levels of 0.1, 0.2, 0.3, 0.4, and 0.5% by weight was added to ground turkey meat to determine if a flavor difference could be detected when STP was present. Detection thresholds for STP in ground turkey meat were determined for 30 female respondents. Two population thresholds were determined using information from the detection thresholds. Two-thirds of the respondents detected a difference between samples with no STP and those with 0.5% STP or less. STP added at less than 0.3% was undetected by more than 50% of the tested population.     

Effect of the particle size of globular nanodisperse carbon on the texture and strength of molded Sibunit-type materials

New large-scale technology can produce porous carbon-carbon composites shaped as 0.5–5 mm grains on the basis of globular nanodisperse carbon (GNC); these composites are referred to as Sibunit. The use of this material as units of more complex shapes, such as rods, tubes, and petals, can help to reduce the hydraulic drag of the sorbent or catalyst bed. The tasks of this study were to manufacture, via extrusion molding, rods on the basis of GNC with various primary particle sizes and to study the effect of GNC particle sizes and heat-treatment parameters on the specific surface area of molded Sibunit. The GNC particle size has a decisive effect on the texture parameters. The greatest specific surface area (600–700 m²/g) was obtained for GNC with particle sizes of (15–20) ± 5 nm with the strength retained at a level of 3–5 N/mm². The results of this work are recommended for use in the development of large-scale technology for manufacturing Sibunit-type supports in various shapes with particle sizes of 2–12 mm and inner channel diameters of 1–6 mm.     

Laser-activated shape memory polymer microactuator for thrombus removal following ischemic stroke: preliminary in vitro analysis

Due to the narrow (3-h) treatment window for effective use of the thrombolytic drug recombinant tissue-type plasminogen activator (rt-PA), there is a need to develop alternative treatments for ischemic stroke. We are developing an intravascular device for mechanical thrombus removal using shape memory polymer (SMP). We propose to deliver the SMP microactuator in its secondary straight rod form (length=4 cm, diameter=350 /spl mu/m) through a catheter distal to the vascular occlusion. The microactuator, which is mounted on the end of an optical fiber, is then transformed into its primary corkscrew shape by laser heating (diode laser, /spl lambda/=800 nm) above its soft-phase glass transition temperature (T/sub gs/=55/spl deg/C). Once deployed, the microactuator is retracted, and the captured thrombus is removed to restore blood flow. The SMP is doped with indocyanine green (ICG) dye to increase absorption of the laser light. Successful deployment of the microactuator depends on the optical properties of the ICG-doped SMP, as well as the optical coupling efficiency of the interface between the optical fiber and the SMP. Spectrophotometry, thermal imaging, and computer simulation aided the initial design effort and continue to be useful tools for optimization of the dye concentration and laser power. Thermomechanical testing was performed to characterize the elastic modulus of the SMP. We have demonstrated laser activation of the SMP microactuator in air at room temperature, suggesting this concept is a promising therapeutic alternative to rt-PA.