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Poly(azolyl)borate ligands have proven to be extremely popular ligands since their introduction by Trofimenko in the late 60´s. The basic skeleton of these ligands involves usually three heterocycle units linked to a central boron apex via the azole nitrogen atoms. These ligands have been applied in diverse research areas such as homogeneous catalysis, materials science and bio-inorganic chemistry. More than 2000 papers, including books and reviews regarding the properties of these compounds, have been published. However, only a few synthetic methods for the preparation of such ligands have been reported and only a few examples of chiral borate-centred ligands are known. This thesis deals with the development of a novel synthetic route to tripodal borate ligands using B(NMe2)3 as the boron source. The mechanism of the reaction of this borane with azole heterocycles has been established by exploring the reactivity of a range of azoles. One of the major features of this new synthetic protocol is that it allows the formation of chiral tripodal ligands where the chiral groups are located either at the forth position at the boron atom or at the azole heterocycles. Coordination studies of the ligands have been undertaken and the metal complexes have been studied by a combination of spectroscopic and X- ray diffraction techniques. Preliminary application of the most representative ligands in the Asymmetric Transfer Hydrogenation (ATH) of prochiral ketones has been undertaken in collaboration with Prof. Dieter Vogt at the Technical University of Eindhoven.

Master of Science / Department of Mechanical and Nuclear Engineering / Jeremy Roberts / The reactivity method is an indirect nondestructive technique to estimate integral burnup in fuel elements. In this method, the assumption is made that reactivity worth of a fuel element is a known function of burnup, often a linear relationship. When a fuel element burns, reactivity is reduced due to depletion of fissile actinides and generation of neutron-absorbing fission products. Currently, there is a lack of experimental data to verify the current composition of the KSU TRIGA (Training Research Isotopes General Atomics) fuel. Moreover, the KSU TRIGA Mark II staff method of estimating burnup is admittedly inaccurate due to its simple approximations. This work presents the positive period technique as convenient method use only the excess reactivity of the KSU core to compute reactivity via the inhour equation. Period measurements are determined via extraction and manipulation of the time dependent power data in the measurements. MCNP and Serpent modeling codes are both used extract the neutron kinetics parameters necessary in the inhour equation. Seven axial discretization of the KSU fuel was modeled, which minimizes the reactivity biases as function of burnup. Moreover, two unit cell models of the KSU TRIGA fuel were investigated. Modeled reactivity worths were computed using the KCODE in MCNP for comparative analysis. The burnup steps using two power peaking factor methods were developed to account for the biases introduced initial burnup of fuel prior to installation at KSU. By using the error distribution given by the two method to generate 200 test cases of the burnup steps can yield to reactivity worths as a function of burnup with quantifiable uncertainties. Finally, the results suggest that validation from another nondestructive technique such as gamma spectroscopy is necessary to asses the reactivity biases observed for higher burnup fuel elements due to unknown radial orientations. This work ultimately supports the production of a high-fidelity model of the KSU reactor.

Gender microaggressions are normative messages that communicate harmful stereotypes or attitudes towards women. Research suggests that being the target of microaggresions may contribute to negative mental and physical health outcomes. The current study examined how gender microaggressions affect emotional and physiological reactivity as well as performance on a working memory task. Results indicated condition (i.e., control vs. sexual objectification microaggression vs. denial of sexism microaggression) did not have a significant affect on reactivity or performance. Issues of population bias and essentialism may have played an important role in study findings. Future directions are discussed.

Introduction: Unhealthy alcohol use is a substantial problem among college students and can lead to a variety of negative consequences. Commercially available web-based brief alcohol intervention (WBI) programs have demonstrated efficacy in a range of student groups and have been widely disseminated to colleges to address this issue. However, the majority of published WBI studies required participants to complete baseline research assessments (RA) about their alcohol use before the WBI and reactivity to the RA may have inflated WBI efficacy estimates in these studies. The present study tested whether there was an additive effect of RA administered online plus a WBI on alcohol consumption, alcohol consequences, and protective behaviors related to alcohol used in the past month compared to the effects of only a WBI. It was hypothesized that participants randomized to the RA+WBI condition would have significantly lower alcohol consumption in the past month, fewer alcohol-related problems, and use more protective behaviors related to alcohol consumption in the past month than participants randomized to the WBI only condition. Methods: Undergraduate students (n= 856) from universities in the United States and Canada were recruited for this online study. Seventy percent of the sample was female and 82% were Caucasian. The sample had a mean age was 20.0. Sixty four percent (n= 547) of participants who were randomized completed the WBI. Sixty-eight percent completed the one month follow up questionnaire. Results: Multiple regression analyses using 20 multiply imputed datasets revealed that there were no significant differences in groups at follow up on alcohol use measures, alcohol related problems, or protective behaviors used when controlling for variables with theoretical and statistical relevance to the models. A repeated measures analysis of covariance indicated that there was a significant decrease in peak estimated blood alcohol concentration from baseline to follow up, but no differential effect by randomization group. The results suggested there was a moderate effect of the WBI consistent with studies of WBI efficacy in the literature and that there were no substantial assessment reactivity effects. Discussion: The current study contributes to the literature by identifying an experimental condition under which assessment reactivity may not be present and does not appear to cloud the detection of WBI efficacy when measured within subjects. The results indicate that WBI researchers may be justified in conducting brief pretreatment research assessments online to collect information about participant alcohol use without biasing within subjects estimates of WBI efficacy. Universities using these programs may likely observe similar effect sizes to those reported in the literature, however effectiveness studies are warranted.

This study uses atomic force microscopy (AFM) to investigate the oxygen etching behavior of the following silicon surface orientations: (001), (111), (113), (5 5 12) and (112). Most etching was performed at sample temperatures between 650 °C and 800 °C, at pressures of 3.3×10-7 and 1.5×10-7 Torr, and at an exposure of 200 L. Surface orientation strongly influences the morphology resulting from extended etching. The surface orientations that are stable against etching and remain flat include Si(001), Si(111), and Si(113). Such surfaces also include island structures, which result from etching around oxide-induced pinning sites. The density of these islands increases at lower temperatures and higher pressures. The surface orientations that are unstable against oxygen etching and facet to other orientations include Si(5 5 12) and Si(112). These surfaces form sawtooth facets that are primarily composed of more stable (111) and (113) planes. By controlling the temperature and exposure during oxygen etching, it is therefore possible to form a variety of surface morphologies.

A thorough understanding of the underlying electronic principles guiding the stability and reactivity of clusters has direct implications for the identification of stable clusters for incorporation into clusters-assembled materials with tunable properties. This work explores the electronic principles governing the stability and reactivity of two types of clusters: ligated metal clusters and silicon encapsulated transition metal clusters. In the first case, the reactivity of iodine-protected aluminum clusters, Al13Ix- (x=0-4) and Al14Iy- (y-0-5), with the protic species methanol was studied. The symmetrical ground states of Al13Ix- showed no reactivity with methanol but reactivity was achieved in a higher energy isomer of Al13I2- with iodines on adjacent aluminum atoms – complementary Lewis acid-base active sites were induced on the opposite side of the cluster capable of breaking the O-H bond in methanol. Al14Iy- (y=2-5) react with methanol, but only at the ligated adatom site. Reaction of methanol with Al14- and Al14I- showed that ligation of the adatom was necessary for the reaction to occur there – revealing the concept of a ligand-activated adatom. In the second case, the study focused heavily on CrSi12, a silicon encapsulated transition metal cluster whose stability and the reason for that stability has been debated heavily in the literature. Calculations of the energetic properties of CrSin (n=6-16) revealed both CrSi12 and CrSi14 to have enhanced stability relative to other clusters; however CrSi12 lacks all the traditional markers of a magic cluster. Molecular orbital analysis of each of these clusters showed the CNFEG model to be inadequate in describing their stability. Because the 3dz2 orbital of Cr is unfilled in CrSi12, this cluster has only 16 effective valence electrons, meaning that the 18-electron rule is not applicable. The moderate stability of CrSi12 can be accounted for by the crystal-field splitting of the 3d orbitals, which pushes the 3dz2 orbital up in energy. CrSi14, on the other hand, has 18 effective valence electrons on Cr, minimal 3d-orbital splitting, and does follow the 18-electron rule. A repetition of these calculations with WSin (n=6-16) showed similar results, except WSi12 shows all the markers of a magic cluster, due to the greater crystal-field splitting of 5d orbitals.

Call number: LD2668 .T4 1986 W43 / Master of Science / Chemistry

Clarifying processes associated with emerging externalizing behavior problems during early childhood was the focus of this study. Data were collected from 100 parent-child dyads when children were 2, 3, and 4 years. An incremental risk model was hypothesized to explain the emergence of externalizing behavior problems. Theoretically, children's temperamental propensity towards negative emotional reactivity increases risk for noncompliance, noncompliance that increases risk for externalizing behaviors by age 4. Parenting was identified as the mechanism by which children's progression along the incremental risk pathway is amplified or minimized; progression is only expected under conditions of harsh parenting. No statistical support emerged for the incremental risk model or the moderational effects of harsh parenting. Harsh parenting was a statistically significant predictor of children's noncompliance one year later. Implications of the current findings for future research are discussed.

The purpose of this study is to examine if testosterone shows reactivity to skydiving and to examine whether the testosterone level and reactivity was associated with sex and sensation seeking trait of the participants. Testosterone is an important steroid hormone which has several biological and socio-behavioral effects on people and is also present in disproportionate amounts in males and females; thus, it is important to explore how this hormone acts in different sex. Furthermore, exploring the relationship between sensation-seeking and testosterone could provide insight into the relation between psychological factor and hormonal response in humans. Forty-four people were recruited to participate in the study. The sample comprised of 73% males (N=32) and 27% females (N=12) with a mean age of 24 years (SD = 4.6) and an age range of 18 to 49. The participants volunteered to jump out of an airplane and give saliva samples at different time points during that day and during another day (basal levels). This study found that testosterone shows reactivity in response to skydiving, where the peak levels in males were higher than in females. It also found that people who scored higher in experience-seeking scores had higher testosterone level at jump than people who scored lower. Furthermore, it also revealed that people who scored higher in intension-seeking scores showed more reactivity in terms of testosterone i.e. the rise was steeper in these people. In summary, we see that psychological factors and sex predicted reactivity and peak level of testosterone after skydiving.