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Metals Retention in Constructed Wetland Sediments

Description: The A-01 wetland treatment system (WTS) was designed to remove metals from the effluent at the A-01 NPDES outfall at the Savannah River Site, Aiken, SC. Sequential extraction data was used to evaluate remobilization and retention of Cu, Pb, Zn, Mn, and Fe in the wetland sediment. Remobilization of metals was determined by the Potentially Mobile Fraction (PMF) and metal retention by the Recalcitrant Factor (RF). The PMF, which includes water soluble, exchangeable, and oxides fractions, is the contaminant fraction that has the potential to enter into the mobile aqueous phase under changeable environmental conditions. PMF values were low for Cu, Zn and Pb (about 20 percent) and high for Fe and Mn (about 60 to 70 percent). The RF, which includes crystalline oxides, sulfides or silicates and aluminosilicates, is the ratio of strongly bound fractions to the total concentration of elements in sediment. RF values were about 80 percent for Cu, Zn and Pb, indicating high retention in the sediment and 30 percent to above 40 percent for Fe and Mn indication low retention.
Date: October 27, 2004
Creator: KNOX, ANNA
Partner: UNT Libraries Government Documents Department

Drug Retention Times

Description: The purpose of this monograph is to provide information on drug retention times in the human body. The information provided is based on plausible illegal drug use activities that might be engaged in by a recreational drug user
Date: May 1, 2007
Creator: Studies, Center for Human Reliability
Partner: UNT Libraries Government Documents Department

Job embeddedness versus traditional models of voluntary turnover: A test of voluntary turnover prediction.

Description: Voluntary turnover has historically been a problem for today's organizations. Traditional models of turnover continue to be utilized in a number of ways in both academia and industry. A newer model of turnover, job embeddedness, has recently been developed in an attempt to better predict voluntary turnover than existing models. Job embeddedness consists of organizational fit, organizational sacrifice, and organizational links. The purpose of this study is to two fold. First, psychometric analyses were conducted on the job embeddedness model. Exploratory factor analyses were conducted on the dimensions of job embeddedness, which revealed a combined model consisting of five factors. This structure was then analyzed using confirmatory factor analysis, assessing a 1, 3, and 5 factor model structure. The confirmatory factor analysis established the use of the 5 factor model structure in subsequent analysis in this study. The second purpose of this study is to compare the predictive power of the job embeddedness model versus that of the traditional models of turnover. The traditional model of turnover is comprised of job satisfaction, organizational commitment, and perceived job alternatives. In order to compare the predictive power of the job embeddedness and traditional model of voluntary turnover, a series of structural equation model analyses were conducting using LISREL. The job embeddedness model, alone, was found to be the best fit with the sample data. This fit was improved over the other two models tested (traditional model and the combination of the traditional and job embeddedness model). In addition to assessing which model better predicts voluntary turnover, it was tested which age group and gender is a better fit with the job embeddedness model. It was found that the job embeddedness model better predicts turnover intention for older respondents and males.
Date: December 2005
Creator: Besich, John
Partner: UNT Libraries

A Test of Incremental and All-or-None Theories of Acquisition by a Measure of Retention of Paired-Associate Learning

Description: Recent research has found that subjects learning a list of paired-associates under conditions requiring one-trial learning are capable of learning a list of paired items in as few a number of trials as subject learning similar lists of paired-associates under a condition using repetition.
Date: August 1966
Creator: Breckenridge, Robert L.
Partner: UNT Libraries

Recommended Library Contributions to STEM Retention Based on an LIS Interpretation of the Landmark Study, Talking about Leaving: Why Students Leave the Sciences

Description: Poster presentation for the American Library Association (ALA) Annual Conference, Association of College and Research Libraries (ACRL) Science and Technology Section Program Poster Session. This poster discusses recommended library contributions to Science, Technology, Engineering and Math (STEM) retention based on a Library and Information Science (LIS) interpretation of a landmark study.
Date: June 19, 2014
Creator: O'Toole, Erin
Partner: UNT Libraries

Key Factors Influencing Retention Rates among Historically Underrepresented Groups in STEM Fields

Description: The aim of the study was to identify the factors that have an influence on the completion rates of undergraduate students in the fields of science, technology, engineering and mathematics (STEM). Using Tinto's retention rate theory as the theoretical foundation, data were collected from freshman who were enrolled in the years 2005 to 2008. Results showed gender and first-generation status were significant predictors of STEM completion and time taken to complete the degree. Institutional bias played a role in race/ethnicity not being a factor affecting completion rates, as this study was conducted at a Predominantly White Institution. SAT scores and first and second-year college GPA showed to have the most prominent influence on both STEM completion rate and time taken to complete the degree. Females with higher first-year college GPA and higher high school rank finished faster. Similar results were found with first-generation students as well. Students belonging to ethnic minority groups with higher SAT scores and college GPA had greater success in STEM fields as well. The study results can be used to increase completion rates of underrepresented students in the STEM fields, given what we know about the interactions between underrepresented student groups and the most important predictors.
Date: December 2018
Creator: Premraj, Divya
Partner: UNT Libraries


Description: This report covers studies of the excretion and retention of 'tracer' and toxic doses of the 11.2-day Ra{sup 223} isotope, its acute toxicity (organ weight changes, gross and microscopic pathology, and Fe{sup 59} utilization by the bone marrow), and long-term histopathological changes and alterations in the hemogram.
Date: February 21, 1958
Creator: Durbin, Patricia; Durbin, Patricia W.; Asling, C. Willet.; Jeung, Nylan; Williams, Marilyn H.; Post, James. et al.
Partner: UNT Libraries Government Documents Department

Factors Related to Teacher Retention: the Lived Experiences of Four Teachers in an Urban, Hard-to-staff High School

Description: Retaining quality teachers is critical to the success of America's schools. How to retain quality teachers, especially in high needs schools, is a question of fervent debate among educational researchers, policy makers, administrators, parents, and students. This study examines the issue of teacher retention from an emic perspective, focused on understanding the perspective of those closest to the retention decision, teachers in hard-to-staff schools. This study examines the lived experiences of four teachers at a hard-to-staff, urban, secondary school as these experiences impact their decisions to remain in teaching and at their current campus. Research methods adopted an existential phenomenological perspective and focused on understanding deeply the perspective of participants and how participants make meaning of their lived experiences as they relate to the retention decision. Three hour-long interviews were conducted with each of the four participants utilizing methodology laid out by Seidman (1991). Data were analyzed using NVIVO 10 to apply a series of coding and recoding procedures to interview transcripts. Conclusions suggest four factors motivated these teachers to teach and remain in their current hard-to-staff, urban, secondary school. These factors include: belief in the power of education, relationships with students, mentoring and professional partnering, and remaining professionally challenged. Findings suggest factors that drive teachers out of teaching and out of hard-to-staff schools include: inconsistent administrative support, low student motivation, and lack of resources.
Date: August 2013
Creator: Julian, Chris
Partner: UNT Libraries

Comparative Analysis of Management and Employee Job Satisfaction and Policy Perceptions.

Description: The purpose of the study was to investigate the perceptions of job satisfaction as defined by management and nonmanagement employees and to compare both parties' perceptions of organizational benefits to a list prepared by the organization's benefit personnel. Turnover is costly to the organization, both in money and in the impact it has on those individuals remaining with the organization. Every effort should be undertaken to reduce the amount of turnover within the organization. A contributing factor leading to turnover may be a gap between what the employees believe is important to them and what management believes is important to the employees. The boundaries of the gap need to be identified before any effort can be made to reduce or bridge the gap. Once the boundaries are identified, policies can be analyzed and the possibility of reducing the gap investigated. Management as a whole must be aware of the needs and wants of their employees before any attempt to develop a retention strategy is undertaken. This knowledge can be acquired only through two-way communication with the employee. The communication process includes the simple process of asking employees for this information and then listening to how they respond. This study suggests that little difference exists in perception of job satisfaction importance for gender, age group, length of time with the organization, topic training hours, and between management and nonmanagement employees. However, perception gaps exist between the job satisfaction items addressed by organizational policies and procedures and those perceived by employees. Additional studies that include a number of varied organizations are needed before extensive generalizations can be made.
Date: May 2003
Creator: Andrews, Charles G.
Partner: UNT Libraries

300 Area Building Retention Evaluation Mitigation Plan

Description: Evaluate the long-term retention of several facilities associated with the PNNL Capability Replacement Laboratory and other Hanfor mission needs. WCH prepared a mitigation plan for three scenarios with different release dates for specific buildings. The evaluations present a proposed plan for providing utility services to retained facilities in support of a long-term (+20 year) lifespan in addition to temporary services to buildings with specified delayed release dates.
Date: July 3, 2007
Creator: McBride, D. J.
Partner: UNT Libraries Government Documents Department


Description: Uranium speciation and retention mechanism onto Savannah River Site (SRS) wetland sediments was studied using batch (ad)sorption experiments, sequential extraction desorption tests and U L{sub 3}-edge X-ray absorption near-edge structure (XANES) spectroscopy of contaminated wetland sediments. U was highly retained by the SRS wetland sediments. In contrast to other similar but much lower natural organic matter (NOM) sediments, significant sorption of U onto the SRS sediments was observed at pH <4 and pH >8. Sequential extraction tests indicated that the U(VI) species were primarily associated with the acid soluble fraction (weak acetic acid extractable) and NOM fraction (Na-pyrophosphate extractable). Uranium L3- edge XANES spectra of the U-retained sediments were nearly identical to that of uranyl acetate. The primary oxidation state of U in these sediments was as U(VI), and there was little evidence that the high sorptive capacity of the sediments could be ascribed to abiotic or biotic reduction to the less soluble U(IV) species. The molecular mechanism responsible for the high U retention in the SRS wetland sediments is likely related to the chemical bonding of U to organic carbon.
Date: June 17, 2013
Creator: Li, D.; CHANG, H.: SEAMAN, J.; Jaffe, P.; Groos, P.; Jiang, D.; Chen, N. et al.
Partner: UNT Libraries Government Documents Department

Drug Retention Times

Description: The purpose of this monograph is to provide information on drug retention times in the human body. The information provided is based on plausible illegal drug use activities that might be engaged in by a recreational drug user.
Date: May 1, 2007
Creator: Studies, Center for Human Reliability
Partner: UNT Libraries Government Documents Department

Report on the deuterium retention in CVD coated W on SiC in support of the Ultramet Company’s Small Business Innovation Research (SBIR) project: SOW DE-FG02-07ER84941

Description: A tungsten (W) coated (0.0005-inch thickness) silicon carbide (SiC) (1.0-inch diameter and 0.19-inch thickness) sample was exposed to a divertor relevant high-flux (~1022 m-2s-1) deuterium plasma at 200 and 400°C in the Idaho National Laboratory’s (INL’s) Tritium Plasma Experiment (TPE), and the total deuterium retention was subsequently measured via the thermal desorption spectroscopy (TDS) method. The deuterium retentions were 6.4x1019 m-2 and 1.7x1020 m-2, for 200 and 400°C exposure, respectively. The Tritium Migration Analysis Program (TMAP) was used to analyze the measured TDS spectrum to investigate the deuterium behavior in the W coated SiC, and the results indicated that most of the deuterium was trapped in the W coated layer even at 400°C. This thin W layer (0.0005-inch ~ 13µm thickness) prevented deuterium ions from bombarding directly into the SiC substrate, minimizing erosion of SiC and damage creation via ion bombardment. The shift in the D desorption peak in the TDS spectra from 200 C to 400°C can be attributed to D migration to the bulk material. This unexpectedly low deuterium retention and short migration might be due to the porous nature of the tungsten coating, which can decrease the solution concentration of deuterium atoms.
Date: June 1, 2012
Creator: Shimada, Masashi
Partner: UNT Libraries Government Documents Department

Hydrogen Release from Irradiated Vanadium Alloy V-4Cr-4Ti

Description: The present work is an attempt to obtain data concerning the influence of neutron and ? irradiation upon hydrogen retention in V-4Cr-4Ti vanadium alloy. The experiments on in-pile loading of vanadium alloy specimens at the neutron flux density 1014 n/cm2s, hydrogen pressure of 80 Pa, and temperatures of 563, 613, and 773 K were carried out using the IVG.1M reactor of the Kazakhstan National Nuclear Center. A preliminary set of loading/degassing experiments with non-irradiated material has been carried out to obtain data on hydrogen interaction with vanadium alloy. The, data presented in this work are related both to non-irradiated and irradiated samples.
Date: September 1, 1999
Creator: Klepikov, A. Kh.; Romanenko, O. G.; Chikhray, E. V.; Tazhibaeva, I. L.; Shestakov, V. P. & Longhurst, Glen Reed
Partner: UNT Libraries Government Documents Department

A Novel Non-Destructive Silicon-on-Insulator Nonvolatile Memory - LDRD 99-0750 Final Report

Description: Defects in silicon-on-insulator (SOI) buried oxides are normally considered deleterious to device operation. Similarly, exposing devices to hydrogen at elevated temperatures often can lead to radiation-induced charge buildup. However, in this work, we take advantage of as-processed defects in SOI buried oxides and moderate temperature hydrogen anneals to generate mobile protons in the buried oxide to form the basis of a ''protonic'' nonvolatile memory. Capacitors and fully-processed transistors were fabricated. SOI buried oxides are exposed to hydrogen at moderate temperatures using a variety of anneal conditions to optimize the density of mobile protons. A fast ramp cool down anneal was found to yield the maximum number of mobile protons. Unfortunately, we were unable to obtain uniform mobile proton concentrations across a wafer. Capacitors were irradiated to investigate the potential use of protonic memories for space and weapon applications. Irradiating under a negative top-gate bias or with no applied bias was observed to cause little degradation in the number of mobile protons. However, irradiating to a total dose of 100 krad(SiO{sub 2}) under a positive top-gate bias caused approximately a 100% reduction in the number of mobile protons. Cycling capacitors up to 10{sup 4} cycles had little effect on the switching characteristics. No change in the retention characteristics were observed for times up to 3 x 10{sup 4} s for capacitors stored unbiased at 200 C. These results show the proof-of-concept for a protonic nonvolatile memory. Two memory architectures are proposed for a protonic non-destructive, nonvolatile memory.
Date: November 1, 1999
Partner: UNT Libraries Government Documents Department

A flexible package and interconnects for microfluidic systems

Description: A slide-together compression package and microfluidic interconnects for microfabricated devices requiring fluidic and electrical connections is presented. The package assembles without tools, is reusable, and requires no epoxy, wirebonds, or solder, making chip replacement fast and easy. The microfluidic interconnects use standard HPLC PEEK tubing, with the tip machined to accept either an o-ring or custom molded ring which serves the dual function of forming the seal and providing mechanical retention strength. One design uses a screw to compress the o-ring, while others are simply plugged into a cartridge retained in the package. The connectors are helium leak-tight, can withstand hundreds of psi, are easy to connect and disconnect, are low dead volume, have a small footprint, and are adaptable to a broad range of microfabricated devices.
Date: January 1, 1999
Creator: Benett, W & Krulevitch, P
Partner: UNT Libraries Government Documents Department

Direct synthesis of LiNi1/3Co1/3Mn1/3O2 from nitrateprecursors

Description: Two novel methods for synthesis of the title compound directly from metal nitrates are described. Phase-pure materials are produced when precursors are calcined between 600 and 1000 C, with little to no ion mixing exhibited for products heated to 900 C or above. The electrochemical characteristics of these materials depended upon calcination temperature and synthesis method, with results comparable to a commercial sample for the materials made at high temperatures in a one-step process without combustion. The sample prepared by combustion also exhibited very stable capacity retention upon cycling.
Date: April 28, 2004
Creator: Patoux, Sebastien & Doeff, Marca M.
Partner: UNT Libraries Government Documents Department