Photocatalytic decomposition of organophosphonates and fluorophenols in irradiated titanium dioxide suspensions

Dimethyl methyl phosphonate (DMMP), diethyl methyl phosphonate (DEMP), and fluorophenols undergo rapid decomposition upon TiO$\sb2$ catalyzed photooxidation in air saturated aqueous solution. The degradation rates of DMMP were determined over a range of temperatures, under solar and artificial irradiation with and without simultaneous sonication. Solar illumination is effective for the degradation and the use of low energy of sonication increases the rate of mineralization. The surface area and the type of TiO$\sb2$ dramatically affect the photoactivity of the catalyst. A number of intermediate products are formed and ultimately oxidized to phosphate and carbon dioxide. Possible reaction mechanisms and pathways for DMMP and DEMP are proposed. The Langmuir-Hinshelwood kinetic parameters for the photocatalysis of fluorophenols suggest modestly different reactivity for each isomer. The adsorption constant is largest for the ortho isomer consistent with the adsorption onto TiO$\sb2$ through both hydroxyl and fluoride groups to form a chelated type structure. ^

Photocatalytic decomposition of organophosphonates fluorophenols in irradiated titanium dioxide suspensions

Dimethyl methyl phosphonate (DMMP), diethyl methyl phosphonate (DEMP), and fluorophenols undergo rapid decomposition upon TiO2 catalyzed photooxidation in air saturated aqueous solution. The degradation rates of DMMP were determined over a range of temperatures, under solar and artificial irradiation with and without simultaneous sonication. Solar illumination is effective for the degradation and the use of low energy of sonication increases the rate of mineralization. The surface area and the type of TiO2 dramatically affect the photoactivity of the catalyst. A number of intermediate products are formed and ultimately oxidized to phosphate and carbon dioxide. Possible reaction mechanisms and pathways for DMMP and DEMP are proposed. The Langmuir- Hinshelwood kinetic parameters for the photocatalysis of fluorophenols suggest modestly different reactivity for each isomer. The adsorption constant is largest for the ortho isomer consistent with the adsorption onto TiO2 through both hydroxyl and fluoride groups to form a chelated type structure.

The effect of iron oxide nanoparticles on the fate and transformation of arsenic in aquatic environments

Iron oxides and arsenic are prevalent in the environment. With the increase interest in the use of iron oxide nanoparticles (IONPs) for contaminant remediation and the high toxicity of arsenic, it is crucial that we evaluate the interactions between IONPs and arsenic. The goal was to understand the environmental behavior of IONPs in regards to their particle size, aggregation and stability, and to determine how this behavior influences IONPs-arsenic interactions. ^ A variety of dispersion techniques were investigated to disperse bare commercial IONPs. Vortex was able to disperse commercial hematite nanoparticles into unstable dispersions with particles in the micrometer size range while probe ultrasonication dispersed the particles into stable dispersions of nanometer size ranges for a prolonged period of time. Using probe ultrasonication and vortex to prepare IONPs suspensions of different particle sizes, the adsorption of arsenite and arsenate to bare hematite nanoparticles and hematite aggregates were investigated. To understand the difference in the adsorptive behavior, adsorption kinetics and isotherm parameters were determined. Both arsenite and arsenate were capable of adsorbing to hematite nanoparticles and hematite aggregates but the rate and capacity of adsorption is dependent upon the hematite particle size, the stability of the dispersion and the type of sorbed arsenic species. Once arsenic was adsorbed onto the hematite surface, both iron and arsenic can undergo redox transformation both microbially and photochemically and these processes can be intertwined. Arsenic speciation studies in the presence of hematite particles were performed and the effect of light on the redox process was preliminary quantified. The redox behavior of arsenite and arsenate were different depending on the hematite particle size, the stability of the suspension and the presence of environmental factors such as microbes and light. The results from this study are important and have significant environmental implications as arsenic mobility and bioavailability can be affected by its adsorption to hematite particles and by its surface mediated redox transformation. Moreover, this study furthers our understanding on how the particle size influences the interactions between IONPs and arsenic thereby clarifying the role of IONPs in the biogeochemical cycling of arsenic.^

A comparative study of high -achieving and low -achieving African -American students in an urban setting

The purpose of this study was to delineate which demographic and school variables were important for predicting the achievement of 10th grade African-American students. The sample population was divided into two groups: high-achievers, students with GPAs of 3.5 or higher, and low-achievers, students with GPAs of 1.5 or lower. Variables examined in the study included: gender; birth place; student's native language; exceptionality (ESE); history of English proficiency (LEP); SES (lunch status) in elementary and high school; the percentage of the Black student population in high school; and suspensions, absences, tardies, and the Stanford Achievement Test (SAT) scores in reading comprehension, mathematics computation, and mathematics applications in elementary and middle school. Two separate logistic regression analyses were conducted to determine which variables were influential in predicting achievement.^ Analysis 1 (N = 366), which included all the variables, except the SAT percentile scores, correctly classified 87% of the students as high-achievers or low-achievers. The results from Analysis 1 revealed that students who--were female; spoke a language other than English as their first language; did not apply for free or reduced lunch in elementary school; were in the gifted program; had no absences or tardies in elementary school; had no suspensions or tardies in middle school; and attended a high school with a lower percentage of Black students--were more likely to be high-achieving than low-achieving.^ Analysis 2 (N = 274) included all the variables and resulted in 94% of the students being correctly classified. It was found that students who--were female; were currently or previously classified as Limited English Proficient (LEP); did not apply for free or reduced lunch in elementary school; had no suspensions or tardies in middle school; and had higher percentile scores in reading comprehension and mathematics computation on the SAT in middle school--were more likely to high-achieving than low-achieving.^ The quantitative analyses were coupled with interviews from a purposeful sample of the population (N = 12) to gain additional insight about why some African-American students are succeeding in our schools and others are not. This study provides a viable means for assessing African-American students' achievement patterns in our schools. ^

Empowerment, social support, and self -esteem of parents involved in an elementary school program

Parent involvement (PI) in schooling has consistently been correlated with improved academic achievement in children. However, despite the apparent benefits of parent involvement, many schools serving low-income communities report consistent difficulty in facilitating the involvement of parents in their children's schooling. ^ The purpose of this exploratory pilot study was to examine key variables associated with a PI program at a school that served a low-income community. The program was selected because it sustained the involvement of parents for a prolonged period of time. It was also selected because the program was facilitated by social workers. ^ Derived from the literature, four lines of inquiry were examined: (a) the relationship between PI and parent strengths and development; (b) the relationship between PI and children's academic achievement; (c) facilitators for PI; and (d) barriers to PI. These lines of inquiry yielded the study's four primary research questions. The study employed a cross-sectional research design to address them. ^ Thirty-three parents, representing 16 school-involved (SI) parents and 17 non-school involved (NSI) parents, served as study participants. All 33 parents resided in a high poverty community. ^ Quantitative methods were selected to examine differences between study participants and PI. Measures of parental empowerment, social support, self-esteem, and direct and indirect measures of their children's academic achievement were utilized. Qualitative methods were developed to identify and describe SI and NSI parents' perceptions of facilitators for and barriers to PI. ^ This study's findings suggest that PI may yield important benefits for SI parents. These benefits include parents' perceptions of their empowerment, social support, and self-esteem. This study's findings also suggest a relationship between PI and reduced rates of children's school suspensions. This study did not, however, support relationships between PI and children's standardized test scores. This study concludes that despite the apparent benefits of PI for SI parents, PI may nonetheless be a proxy for several unspecified interventions that effect parents, children, schools and communities alike. More precise specifications and robust measures of PI are needed. ^

Investigation of escape and negative student behaviors related to Florida state high stakes test preparation in Miami-Dade County Public High Schools

The purpose of this study was to determine whether there was a relationship between pressure to perform on state mandated, high-stakes tests and the rate of student escape behavior defined as the number of school suspensions and absences. The state assigned grade of a school was used as a surrogate measure of pressure with the assumption that pressure increased as the school grade decreased. Student attendance and suspension data were gathered from all 33 of the regular public high schools in Miami-Dade County Public Schools. The research questions were: Is the number of suspensions highest in the third quarter, when most FCAT preparation takes place for each of the 3 school years 2007-08 through 2009-10? How accurately does the high school's grade predict the number of suspensions and number of absences during each of the 4 school years 2005-06 through 2008-09? The research questions were answered using repeated measures analysis of variance for research question #1 and non-linear multiple regression for research question #2. No significant difference could be found between the numbers of suspensions in each of the grading periods nor was there a relationship between the number of suspensions and school grade. A statistically significant relationship was found between student attendance and school grade. When plotted, this relationship was found to be quadratic in nature and formed a loose inverted U for each of the four years during which data were collected. This indicated that students in very high and very low performing schools had low levels of absences while those in the midlevel of the distribution of school performance (C schools) had the greatest rates of absence. Identifying a relationship between the pressures associated with high stakes testing and student escape behavior suggests that it might be useful for building administrators to reevaluate test preparation activities and procedures being used in their building and to include anxiety reducing strategies. As a relationship was found, it sets the foundation for future studies to identify whether testing related activities are impacting some students emotionally and are causing unintended consequences of testing mandates.

Empowerment, social support, and self-esteem of parents involved in an elementary school program

Parent involvement (PI) in schooling has consistently been correlated with improved academic achievement in children. However, despite the apparent benefits of parent involvement, many schools serving low-income communities report consistent difficulty in facilitating the involvement of parents in their children's schooling. The purpose of this exploratory pilot study was to examine key variables associated with a PI program at a school that served a low-income community. The program was selected because it sustained the involvement of parents for a prolonged period of time. It was also selected because the program was facilitated by social workers. Derived from the literature, four lines of inquiry were examined: (a) the relationship between PI and parent strengths and development; (b) the relationship between PI and children's academic achievement; (c) facilitators for PI; and (d) barriers to PI. These lines of inquiry yielded the study's four primary research questions. The study employed a cross-sectional research design to address them. Thirty-three parents, representing 16 school-involved (SI) parents and 17 nonschool involved (NSI) parents, served as study participants. All 33 parents resided in a high poverty community. Quantitative methods were selected to examine differences between study participants and PI. Measures of parental empowerment, social support, self-esteem, and direct and indirect measures of their children's academic achievement were utilized. Qualitative methods were developed to identify and describe SI and NSI parents' perceptions of facilitators for and barriers to PI. This study's findings suggest that PI may yield important benefits for SI parents. These benefits include parents' perceptions of their empowerment, social support, and self-esteem. This study's findings also suggest a relationship between PI and reduced rates of children's school suspensions. This study did not, however, support relationships between PI and children's standardized test scores. This study concludes that despite the apparent benefits of PI for SI parents, PI may nonetheless be a proxy for several unspecified interventions that effect parents, children, schools and communities alike. More precise specifications and robust measures of PI are needed.

The Effect of Iron Oxide Nanoparticles on the Fate and Transformation of Arsenic in Aquatic Environments

Iron oxides and arsenic are prevalent in the environment. With the increase interest in the use of iron oxide nanoparticles (IONPs) for contaminant remediation and the high toxicity of arsenic, it is crucial that we evaluate the interactions between IONPs and arsenic. The goal was to understand the environmental behavior of IONPs in regards to their particle size, aggregation and stability, and to determine how this behavior influences IONPs-arsenic interactions. A variety of dispersion techniques were investigated to disperse bare commercial IONPs. Vortex was able to disperse commercial hematite nanoparticles into unstable dispersions with particles in the micrometer size range while probe ultrasonication dispersed the particles into stable dispersions of nanometer size ranges for a prolonged period of time. Using probe ultrasonication and vortex to prepare IONPs suspensions of different particle sizes, the adsorption of arsenite and arsenate to bare hematite nanoparticles and hematite aggregates were investigated. To understand the difference in the adsorptive behavior, adsorption kinetics and isotherm parameters were determined. Both arsenite and arsenate were capable of adsorbing to hematite nanoparticles and hematite aggregates but the rate and capacity of adsorption is dependent upon the hematite particle size, the stability of the dispersion and the type of sorbed arsenic species. Once arsenic was adsorbed onto the hematite surface, both iron and arsenic can undergo redox transformation both microbially and photochemically and these processes can be intertwined. Arsenic speciation studies in the presence of hematite particles were performed and the effect of light on the redox process was preliminary quantified. The redox behavior of arsenite and arsenate were different depending on the hematite particle size, the stability of the suspension and the presence of environmental factors such as microbes and light. The results from this study are important and have significant environmental implications as arsenic mobility and bioavailability can be affected by its adsorption to hematite particles and by its surface mediated redox transformation. Moreover, this study furthers our understanding on how the particle size influences the interactions between IONPs and arsenic thereby clarifying the role of IONPs in the biogeochemical cycling of arsenic.

Investigation of Escape and Negative Student Behaviors Related to Florida State High Stakes Test Preparation in Miami-Dade County Public High Schools, having been approved in respect to style and intellectual content, is referred to you for judgment

The purpose of this study was to determine whether there was a relationship between pressure to perform on state mandated, high-stakes tests and the rate of student escape behavior defined as the number of school suspensions and absences. The state assigned grade of a school was used as a surrogate measure of pressure with the assumption that pressure increased as the school grade decreased. Student attendance and suspension data were gathered from all 33 of the regular public high schools in Miami-Dade County Public Schools. The research questions were: Is the number of suspensions highest in the third quarter, when most FCAT preparation takes place for each of the 3 school years 2007-08 through 2009-10? How accurately does the high school’s grade predict the number of suspensions and number of absences during each of the 4 school years 2005-06 through 2008-09? The research questions were answered using repeated measures analysis of variance for research question #1 and non-linear multiple regression for research question #2. No significant difference could be found between the numbers of suspensions in each of the grading periods nor was there a relationship between the number of suspensions and school grade. A statistically significant relationship was found between student attendance and school grade. When plotted, this relationship was found to be quadratic in nature and formed a loose inverted U for each of the four years during which data were collected. This indicated that students in very high and very low performing schools had low levels of absences while those in the midlevel of the distribution of school performance (C schools) had the greatest rates of absence. Identifying a relationship between the pressures associated with high stakes testing and student escape behavior suggests that it might be useful for building administrators to reevaluate test preparation activities and procedures being used in their building and to include anxiety reducing strategies. As a relationship was found, it sets the foundation for future studies to identify whether testing related activities are impacting some students emotionally and are causing unintended consequences of testing mandates.