Concentrator cell methodology in the regeneration and recycle of chromium etching solutions using membrane technology

The regeneration of chromium (VI) and the recovery of etched copper from chromium etching solutions by electrodialysis is improved by the addition of a concentrator cell, using ion exchange resins or activated carbon cloth as concentrator media, in the catholyte chamber. The maximum percentages for the regeneration of chromium and recovery of copper in these systems is however less than 80 and 90% respectively because of the competition between the processes of oxidation of Cr(III) and electrodeposition of copper. A novel combination of electrolysis with electrodialysis and concentrator cell technology is developed that achieves 92.1% chromium regeneration and 90.4% copper recovery.EPSRC/DTI through the Link WMR03 programme and to Fluid Dynamics International Ltd. for financial support

Effects of Open Court on Students\u27 Spelling

The purpose of this research is to explore the effects the Open Court phonics instruction has on students\u27 spelling. The current study intends to find the answers to two questions. The first question is: What Open Court phonetic rules and patterns are first grade students using in daily writing and. on spelling assessments? In order to discover this, I will be analyzing two sets of data. At the beginning of the study, a qualitative spelling inventory will be given to determine the students\u27 current stage. I will also look at children\u27s informal journal writing to look for Open Court phonetic rules and patterns. After the study, the same qualitative spelling inventory will be given to measure learning

Population Growth and Other Statistics of Middle-sized Irish Towns. General Research Series Paper No. 85, April 1976

The basic aim of the study is the presentation of tables of comparative statistical data relating to 97 towns with population 5OO-1O,OOO in 1971 and analyses of such data. The exclusion of the four County Boroughs and Dun Laoghaire together with twelve other large towns and all small towns and villages, was to impart a degree of homogeneity to the inquiry, as regards function of town. The 97 towns range from Mullingar, the largest with a population of 9,245 to Cootehill with 1,542

Temporal and spatial dynamics of spawning, settlement, and growth of gray snapper (Lutjanus griseus) from the West Florida shelf as determined from otolith microstructures

The goal of our study was to understand the spatial and temporal variation in spawning and settlement of gray snapper (Lutjanus griseus) along the West Florida shelf (WFS). Juvenile gray snapper were collected over two consecutive years from seagrass meadows with a benthic scrape and otter trawl. Spawning, settlement, and growth patterns were compared across three sampling regions (Panhandle, Big bend, and Southwest) by using otolith microstructure. Histology of adult gonads was also used for an independent estimate of spawning time. Daily growth increments were visible in the lapilli of snapper 11–150 mm standard length; ages ranged from 38 to 229 days and estimated average planktonic larval duration was 25 days. Estimated growth rates ranged from 0.60 to 1.02 mm/d and did not differ among the three sampling regions, but did differ across sampling years. Back-calculated fertilization dates from otoliths indicated that juveniles in the Panhandle and Big Bend were mainly summer spawned fish, whereas Southwest juveniles had winter and summer fertilization dates. Settlement occurred during summer both years and in the winter of 1997 for the southern portion of the WFS. Moon phase did not appear to be strongly correlated with fertilization or settlement. Histological samples of gonads from adults collected near the juvenile sampling areas indicated a summer spawning period

Expressions for Evaluating the Possibility of Slip at the Liquid-Solid Interface in Open Tube Capillary Electrochromatography

In this work, expressions are constructed and solved that describe the velocity field of electroosmotic flow (EOF) in open tube capillary electrochromatography (CEC) systems when the possibility of having unequal tangential velocities at the liquid-solid interface is considered and a slip condition is employed as a boundary condition for the velocity of the EOF at the capillary wall. the coupled equations of hydrodynamics (momentum balance equation) and electrostatics (Poisson equation) are solved numerically in order to obtain the distribution of the velocity field as well as the value of the volumetric flow rate in the open tube. Also, expressions for the velocity field and the volumetric flow rate of the EOF are presented that are valid for certain electrolytic systems and for certain parameter values for which analytical solutions to the momentum balance and Poisson equations could be obtained. the results presented in this work indicate that having slip in the velocity of the EOF at the wall of the capillary could (i) substantially increase the electroosmotic velocity in the plug-flow region of the radial domain of the open capillary tube and (ii) increase the portion of the radial domain of the open capillary tube where the velocity of the EOF has a plug-flow profile, which in turn could increase the average velocity and volumetric flow rate of the EOF in the open capillary tube. Furthermore, the modeling approach and the results presented in this work indicate a method for experimentally evaluating the possibility of having slip in the velocity of the EOF at the capillary wall. © 2003 Elsevier Science (USA). All rights reserved

The Evolution and Implications of the Concentration Profiles of an Analyte in Porous Adsorbent Particles Packed in a Capillary Electrochromatography Column Operated in the Analytical Mode

In this work, a mathematical model is constructed and solved to describe the propagation and dispersion of the mass wave of an analyte in a capillary electrochromatography (CEC) column packed with porous adsorbent particles and operated in the analytical mode. The evolution and dynamic behavior of the isoconcentration contours of the concentration of the analyte in the pores of the particles are presented in order to demonstrate the significant impact that the velocity of the intraparticle electroosmotic flow (EOF) encountered in CEC systems could have in reducing the overall intraparticle mass transfer resistance. It is shown that under both unretained and retained conditions the intraparticle EOF causes a significant departure in the spherical symmetry of the isoconcentration contours of an analyte in the pores of spherical porous adsorbent particles. The asymmetric isoconcentration contours clearly indicate how the intraparticle EOF leads to highly resolved and evenly distributed mass waves of an analyte in the effluent stream of the CEC column and provide efficient separation performance. Furthermore, comments are presented that describe the conditions that could be encountered in CEC systems which could significantly increase the overall intraparticle mass transfer resistance as well as the mass transfer resistance in the interstitial channels for bulk flow and lead to inefficient separation performance

Modeling and Analysis of the Electrokinetic Mass Transport and Adsorption Mechanisms of a Charged Adsorbate in Capillary Electrochromatography Systems Employing Charged Nonporous Adsorbent Particles

Mass-transfer systems based on electrokinetic phenomena (i.e., capillary electrochromatography (CEC)) have shown practical potential for becoming powerful separation methods for the biotechnology and pharmaceutical industries. A dynamic mathematical model, consisting of the momentum balance and the Poisson equations, as well as the unsteady-state continuity expressions for the cation and anion of the background electrolyte and of a positively charged analyte (adsorbate), is constructed and solved to determine quantitatively the electroosmotic velocity, the electrostatic potential, the concentration profiles of the charged species in the double layer and in the electroneutral core region of the fluid in the interstitial channels for bulk flow in the packed chromatographic column, and the axial current density profiles as the adsorbate adsorbs onto the negatively charged fixed sites on the surface of the nonporous particles packed in the chromatographic column. The frontal analysis mode of operation is simulated in this work. The results obtained from model simulations provide significant physical insight into and understanding of the development and propagation of the dynamic profile of the concentration of the adsorbate (analyte) and indicate that sharp, highly resolved adsorption fronts and large amounts of adsorbate in the adsorbed phase for a given column length can be obtained under the following conditions: (i) The ratio, γ2,0, of the electroosmotic velocity of the mobile liquid phase at the column entrance after the adsorption front has passed the column entrance to the electrophoretic velocity of the anion is very close to -1. The structure of the equations of the model and model simulations indicate that a stable adsorption front cannot develop when γ2,0 is less than -1 unless the value of the mobility of the cation is less than the value of the mobility of the analyte, which may be a rare occurrence in practical CEC systems. (ii) The ratio of the mobility of the cation to the mobility of the analyte is less than two orders of magnitude. This effect becomes more significant as the value of the equilibrium adsorption constant, KA,3, of the analyte increases. (iii) The concentration of the analyte relative to the concentration of the cation is increased (feed solutions with less dilute concentrations of the analyte are employed). Therefore, to obtain good performance for CEC systems operated in the frontal analysis mode (well-resolved adsorption fronts and high adsorbate amounts in the adsorbed phase), one can choose an electrolyte whose cation has a mobility that is not more than one or two orders of magnitude greater than the mobility of the analyte and whose anion has a mobility such that the value of γ2,0 is close to -1; one can then bring the value of γ2,0 closer to -1 by decreasing the particle diameter, dp, and/or making the value of the surface charge density, δ0, of the particles more negative (in effect, making the value of the zeta potential, ζp, at the surface of the particles more negative at time t = 0) to change the value of the velocity, 〈υx〉|x=0, of the electroosmotic flow (EOF) at the column entrance (〈υx〉|x=0 is determined after the adsorption front has passed the column entrance). This approach could provide conditions in the column that avoid overloading of the adsorbate. One can obtain faster breakthrough times at the sacrifice of resolution and utilization of the adsorptive capacity of the packed bed if one employs a cation whose mobility is very large relative to the mobility of the analyte and/or an anion that provides a value of γ2,0 significantly greater than -1. If it is possible, one can increase the concentration of the analyte in the feed stream to avoid sacrificing resolution and adsorptive capacity of the packed bed and still decrease the time at which breakthrough occurs. Also, the dynamic behavior of the axial current density, ix, profiles indicates that the magnitude of ix and/or the change in the value of ix across the adsorption front could serve as a measurement for the rate of propagation of the adsorption front through the column. Furthermore, the effect of the decreased magnitude of the velocity of the EOF in the region of the column where the analyte is present in the adsorbed phase could act to decrease the effect of tailing when CEC systems are operated in the pulse injection mode (analytical electrochromatography) because the higher velocity of the fluid upstream of the migrating adsorption zone may compress the tail of the peak. © 2001 Academic Press

Exploring Wage Determination by Education Level: A U.S. MSA Analysis for 2005-2012

The purpose of this study is to explain urban wage differentials with a special focus on educational levels. The authors explore whether the share of people with a bachelor’s degree or higher in the community matters to the wages of those within specific educational cohorts, accounting for cost of living, human capital externalities, consumer externalities, policy factors, and local labor market conditions. Using data for all U.S. Metropolitan Statistical Areas between 2005 and 2012, the authors find that the presence of more highly educated people will result in a higher median wage in the community overall, as do many studies, but that this factor does not significantly increase the wage for any individual education cohort. These results are hidden if we only look at the entire workforce in the aggregate

Diets of Young King and Spanish Mackerel Off the Southeast United States

The diet of larval and post-larval (n = 95 and 307), and juvenile (n = 489 and 508) king (Scomberomorus cavalia) and Spanish mackerel (S. maculatus) from the Gulf of Mexico and southeastern Atlantic coastal waters of the U.S. consisted principally of fishes. Carangids, clupeids, and engraulids occurred in 23, 7 and 9% of larval and post-larval king mackerel stomachs and in 20, 40 and 7% of larval and post-larval Spanish mackerel stomachs, respectively. Sciaenids were also common in king mackerel, occurring in 21% of the stomachs. Prey fishes included the genera Cynoscion, Caranx, and Anchoa, and the species Opisthonema oglinum. Invertebrates, principally small crustaceans and nudibranch larvae, occurred infrequently in the diets of both species, but more so in Spanish mackerel than king mackerel. The dominant prey items for juvenile mackerels from the Atlantic were engraulids, clupeids, balistids, and squids, collectively accounting for 73.3% by volume of the diet of king mackerel and 88.8% of Spanish mackerel. More invertebrates occurred in the diet of juvenile Spanish mackerel than king mackerel, but they accounted for a smaller volume, i.e., 2.1% as compared to 5.4% for the Atlantic fish. Chi-square tests indicated significant differences between the diets of juvenile mackerel from the Gulf of Mexico and the Atlantic coast