Ion exchange technology in the sodium and ferric ion-dowex 50 systems

This investigation was directed toward the extension of data on the kinetics of monovalent - trivalent cation exchange and to establish data on the relationship between temperature and total capacity of an ion exchange resin. In order to compare the present study to a previous investigation by Klosowski (2), the capacity of the resin used for ferric and chromic ions was also measured. In the kinetic study, the ferric ion-hydrogen ion exchange using Dowex 50 X-8 resin was studied in an agitated vessel. A two-bladed marine type propellor was used and the agitator speed was varied from 400 to 800 rpm. The exchange rates were measured for seven different particle size ranges from -16 mesh to +200 mesh. The results of the kinetic study shows that within the range of variables studied, the exchange rate is film diffusional controlled for this system. The exchange rate varied directly with the agitator speed and inversely with the particle size range. The equation proposed by Reichenberg (6) for the calculation of film thickness gave results which agree with the experimental data for particle sizes from -16 to +60 mesh but failed for particle sizes below 70 mesh. At 400, 600, and 800 rpm the average film thicknesses calculated for the ferric ion Dowex 50 system are within 6%, 1%, and exactly equal to the corresponding values of the chromic ion Dowex 50 system. Since the diffusion coefficients for the ferric and chromic ion systems are 0.57x10-5 and 0.642x10-5 cm2/sec. respectively, the agreement on the values of the film thicknesses are as expected. In view of this agreement, the experimental procedure used in this thesis with a modified form of the Reiohenberg Equation is proposed as a method for the determination of diffusion coefficients. In applying this method one would determine the rate of ion exchange at 600 rpm for a screened Dowex 50 resin fraction and then substitute the data taken in the equation shown below. D = 0.0051 r/(Co) dØ/dt where D - Diffusion coefficient r - Average particle radius Co - Initial concentration in the bulk solution dØ/dt - Exchange rate per unit volume This method would greatly simplify the determination of these coefficients but would be subject to the assumptions given in the section on Calculations. The principal assumptions are that the exchange process is film diffusional controlled and that the process is carried out in dilute aqueous solutions in view of possible viscosity changes. The results of the kinetic study can also be successfully applied to increase the efficiency of various methods which have been proposed for continuous ion exchange. In the mixer settler method proposed by Hiester (13), the present study indicates that optimum mixer conditions could be selected for any system based on the relationship between film thickness and agitator speed. From this relationship it would be possible to establish an optimum agitator speed. Once this speed was established, the exchange rate could be calculated using the Reichenberg Equation and the film thickness given in this study. In the capacity vs temperature phase of this investigation, the amount of sodium ion hydrogen ion exchange was measured at temperatures from 0° to 100°C. using Dowex 50 X-8 and X-2 resin. The effect of regeneration temperature was also tested. No change in the total resin capacity was found by variation in the loading temperature for either Dowex 50 X-8 or X-2 ion exchange resins. Some change in total capacity was effected, however, by variation in the regeneration temperature from ambient to 65°C. The capacity of Dowex 50 X-8 ion exchange resin as determined for ferrie ion and chromic ion was 13.2 and 9.89 meq. per gram of dry resin respectively. Manufacturer\u27s specification for this resin for monovalent ions is 5.0 +/- 0.3 meq. per dry gram. No data on the capacities for di and trivalent ions are available

Exploring Voice as Integration: A Direction for Assessing Student Work in Learning Communities with Composition

Kennesaw State University’s team of interdisciplinary scholars qualitatively assessed student learning within theme-based learning communities to determine whether content from one discipline was evident in student work produced within another discipline. Faculty concluded that they were likely expecting more disciplinary integration than first-semester college students were capable of providing, and that they were likely not asking for the integration they were expecting. By examining student work as evidence, the researchers became more acutely aware of the assignment instructions, prompting them to work more closely with colleagues in their future learning communities to develop interdisciplinary assignments with explicit expectations for integration

Integrating Modern-Day Slavery into Interdisciplinary First-Year Seminars

One of the contributing causes of trafficking is its seeming invisibility, especially in the United States. Traditional-age college students arrive on campus having been taught a pervasive cultural myth throughout their years of education. That myth is that slavery was abolished in the United States in the 1800s. It is no longer a social issue demanding concern or attention. It can\u27t happen here -- for a myriad of issues. Yet, conservative estimates point to at least 200,000 individuals being enslaved in the United States at any moment in time. Part of the role of the academy is to make these invisible problems visible, to spark critical thinking regarding complex social issues, and to engage the next generation of leaders in the exploration of both causes and possible solutions. Our work with first-year college students suggests that they are not aware of modern-day slavery, yet they are quite ready to get engaged in the fight to eradicate it once they have the knowledge. We would like to discuss how to integrate the teaching of modern-day slavery into first-year seminar courses, a growing interdisciplinary curricular option on many campuses, and provide data illustrating its effectiveness at one institution. This presentation will be both theoretical and highly practical, combining data analysis with dialogue about what worked on our own campus and what might work on other campuses. We will also provide participants with curricular materials to help them integrate modern-day slavery into their courses. [ The Download document (upper right) is a PDF file generated from the PowerPoint presentation; the Additional file (below) is the Powerpoint slides themselves.

Let Your Conscience Be Your Guide: Smoking and Drinking in Disney\u27s Animated Classics

Disney films have long interested effects researchers, who have consistently shown the wholesome image generated by the company is misrepresentative. This content analysis explored tobacco and alcohol exposure in 24 Disney G-rated, animated, feature- length motion pictures from 1937 to 2000 and found 381 incidents of substance use. Over the decades, tobacco use tended to decrease while alcohol use increased. Virtually no antiuse messages were seen in these films directed to young children

Quality Standards in Children\u27s Programming: An Independent Observation of Industry Claims

There is no standard definition for quality children\u27s programming currently. This study sought to build from the work of Alexander, Hoerrner, and Duke (1998) and others in constructing a standardized definition. The Alexander et al. study defined the television industry\u27s definition of quality. This project analyzed the attributes of the shows used in the 1998 study to determine if the content actually contained the aspects of quality stated by the industry. In doing so, this project sought to validate the television industry\u27s self-imposed definition. The results were quite encouraging; consistency exists among several researchers\u27 and industry definitions.Six categories set the standards for quality: instructional excellence, distinctive program characteristics, production excellence, age appropriateness, diversity, and prestigious participant

Metalloproteinases, tissue inhibitor, and proteoglycan fragments in knee synovial fluid in human osteoarthritis

Objective. To determine the concentrations of human stromelysin-1, collagenase, tissue inhibitor of metalloproteinases (TIMP), and proteoglycan fragments in knee synovial fluid in patients with injury to the meniscus or anterior cruciate ligament, posttraumatic osteoarthritis, primary osteoarthritis, or pyrophosphate arthritis. Methods. Synovial fluid samples were collected from patients with knee disease diagnosed arthroscopically and radiologically. Concentrations of stromelysin-1, collagenase, and TIMP-1 were determined by sandwich immunoassay, using monoclonal and polyclonal antibodies. Fragments of cartilage proteoglycan containing the chondroitin sulfate-binding region were determined by immunoassay with a polyclonal antibody. Results. Average concentrations of metalloproteinases, TIMP, and proteoglycan fragments in joint fluid were significantly elevated in patients from all disease groups as compared with volunteers with healthy knees (reference group). Stromelysin concentrations in disease groups averaged 15-45 times that of the reference group. The molar ratios between stromelysin and collagenase varied between 10 and 150. The molar ratio between total stromelysin and free TIMP was 0.5 in the reference group and between 1.6 and 5.3 in the disease groups. Conclusion. Stromelysin concentration in joint fluid is a parameter that distinguishes diseased joints from healthy joints, with a sensitivity of 84% and a specificity of 90%. The high concentrations of metalloproteinase relative to TIMP in joint fluid from patients with the conditions studied may be associated with cartilage matrix degradation in these arthritides