Intrinsic Oxygen Vacancy and Extrinsic Aluminium Dopant Interplay: A Route to the Restoration of Defective TiO2_2

Density functional theory (DFT) and DFT corrected for on-site Coulomb interactions (DFT+U) calculations are presented on Aluminium doping in bulk TiO$_2$ and the anatase (101) surface. Particular attention is paid to the mobility of oxygen vacancies throughout the doped TiO$_2$ lattice, as a means by which charge compensation of trivalent dopants can occur. The effect that Al doping of TiO$_2$ electrodes has in dye sensitised solar cells is explained as a result of this mobility and charge compensation. Substitutional defects in which one Al3+ replaces one Ti4+ are found to introduce valence band holes, while intrinsic oxygen vacancies are found to introduce states in the band-gap. Coupling two of these substitutional defects with an oxygen vacancy results in exothermic defect formation which maintain charge neutrality. Nudged elastic band calculations have been performed to investigate the formation of these clustered defects in the (101) surface by oxygen vacancy diffusion, with the resulting potential energy surface suggesting energetic gains with small diffusion barriers. Efficiency in- creases observed in dye sensitised solar cells as a result of aluminium doping of TiO$_2$ electrodes are investigated by adsorbing the tetrahydroquinoline C2-1 chromophore on the defective surfaces. Adsorption on the clustered extrinsic Al3+ and intrinsic oxygen vacancy defects are found to behave as if adsorbed on a clean surface, with vacancy states not present, while adsorption on the oxygen vacancy results in a down shift of the dye localised states within the band-gap and defect states being present below the conduction band edge. Aluminium doping therefore acts as a benign dopant for 'cleaning' TiO$_2$ through oxygen vacancy diffusion.Comment: 32 pages, 15 figures, accepted for publication by J. Phys. Chem.

Linear Scaling Density Matrix Real Time TDDFT: Propagator Unitarity \& Matrix Truncation

Real time, density matrix based, time dependent density functional theory proceeds through the propagation of the density matrix, as opposed to the Kohn-Sham orbitals. It is possible to reduce the computational workload by imposing spatial cut-off radii on sparse matrices, and the propagation of the density matrix in this manner provides direct access to the optical response of very large systems, which would be otherwise impractical to obtain using the standard formulations of TDDFT. Following a brief summary of our implementation, along with several benchmark tests illustrating the validity of the method, we present an exploration of the factors affecting the accuracy of the approach. In particular we investigate the effect of basis set size and matrix truncation, the key approximation used in achieving linear scaling, on the propagator unitarity and optical spectra. Finally we illustrate that, with an appropriate density matrix truncation range applied, the computational load scales linearly with the system size and discuss the limitations of the approach.Comment: Accepted for publication in J. Chem. Phy

DSSC Anchoring Groups: A Surface Dependent Decision

Electrodes in dye sensitised solar cells (DSSCs) are typically nanocrystalline anatase TiO2 with a majority (101) surface exposed. Generally the sensitising dye employs a carboxylic anchoring moiety through which it adheres to the TiO2 surface. Recent interest in exploiting the properties of differing TiO2 electrode morphologies, such as rutile nanorods exposing the (110) surface and anatase electrodes with high percentages of the (001) surface exposed, begs the question of whether this anchoring strategy is best, irrespective of the majority surface exposed. Here we address this question by presenting density functional theory calculations contrasting the binding properties of two promising anchoring groups, phosphonic acid and boronic acid, to that of carboxylic acid. Anchor-electrode interactions are studied for the pro- totypical anatase (101) surface, along with the anatase (001) and rutile (110) surfaces. Finally the effect of using these alternative anchoring groups to bind a typical coumarin dye (NKX- 2311) to these TiO2 substrates is examined. Significant differences in the binding properties are found depending on both the anchor and surface, illustrating that the choice of anchor is necessarily dependent upon the surface exposed in the electrode. In particular the boronic acid is found to show the potential to be an excellent anchor choice for electrodes exposing the anatase (001) surface.Comment: 44 pages, 15 figures, accepted by J. Phys.:Condens. Matter. Coordinates for structures available via figshar

Assessing student perceptions of the Pharm.D. degree at a private tertiary medical university in India

Background: Pharmacy education in India has expanded to include the Doctorate of Pharmacy degree (Pharm.D.). With clinical practice in early development, job opportunities in India are limited. Graduates often consider pharmacy opportunities abroad. Aims: This study compares Indian students’ career aspirations related to the Pharm.D. degree before and after beginning their programmes. Methods: A 5-point Likert scale paper survey with open ended questions was distributed to all Pharm.D. students (Year 1- 6) at a medical university in India. Results: With a response rate of 83% (144/173), over half of the students’ primary goal was to pursue careers abroad post-graduation (54.2% before, 51.4% after). Data from the last three graduating classes indicated that 28.3% travelled abroad for future studies while 62.3% secured positions in India. Conclusions: Opportunities abroad remain challenging for Indian trained Pharm.D.s’; graduates may consider the expanding clinical opportunities in India

Juxtaposition: The Coexistence of Traditional Navajo and Standards Based Curricula

Northridge Elementary, a small public school serving almost entirely Navajo students, was recently labeled with a failing grade from the New Mexico Department of Education. This study explores what this label reveals and what it conceals. Using educational connoisseurship and criticism as the method of inquiry, this study considers how the label interacts with the structural, intentional, curricular, pedagogical, and evaluative dimensions within the school. As offered in the thematic aspect of the analysis, the label overgeneralizes realities of Northridge Elementary and is hindering rather the benefiting students

When Two Worlds Collide: Shared Experiences of Educating Navajos Living off the Reservation

Northridge Elementary calls into question the norm - based ideals of the No Child Left Behind Act (2001). By constructing a portrait of Northridge, this study reveals the challenges indigenous students face in the ag e of standardized assessments. The overarching quest ion of this study is: Do high - stakes assessments further the endemic values of colonization? The term colonization in this study refers to federal and state governmental agencies directing what indigenous students should be taught at school despite cultural relevance. This study applies the theoretical framework of Tribal Critical Race Theory (TribalCrit), through video photography, observations, interviews with former students, and a teacher focus group to construct portraiture of the educational realities indigenous students face in a standardized education system

The Relationship Between Prior Experiences in Mathematics and Pharmacy School Success

Objective. To assess students’ pre-pharmacy math experiences, confidence in math ability, and relationship between experiences, confidence, and grades in math-based pharmacy courses. Methods. A cross-sectional survey of first year to third year pharmacy students was conducted. Students reported type of pre-pharmacy math courses taken, when they were taken [high school (HS) vs. college] and year of HS and college graduation. Students rated their confidence in math ability using the previously validated 11-item Fogerty Math Confidence Scale (Cronbach alpha=0.92). Math grade point average (GPA), Pharmacy College Admission Test quantitative (PCAT quant) scores, and grades (calculations and kinetics) were obtained from transcripts and school records. Spearman correlation and multivariate linear regression were used to compare math experiences, confidence, and grades. Results. There were 198 students who reported taking math courses 7.1 years since HS graduation and 2.9 years since their last schooling prior to pharmacy school. Students who took math courses with more time since HS/last schooling had lower calculations and kinetics grades. Students reporting having taken more HS math courses had better calculations grades. Students with higher math GPA, and PCAT quant scores also had higher calculations and kinetics grades. Greater confidence in math ability was associated with higher calculations grades. In multivariate regressions, PCAT quant scores and years since HS independently predicted calculations grades, and PCAT quant scores independently predicted kinetics grades. Conclusion. The number of pre-pharmacy math courses and time elapsed since they were taken are important factors to consider when predicting a pharmacy student’s success in math-based pharmacy school courses

The Ideal Museum vs. The Real Museum: How do Museums in Western New York Implement Preventive Conservation?

This thesis examines the need for preventive conservation in museums. Preventive conservation is an effort aimed at reducing damage and deterioration to collections by improving the environment. Out of the 4.8 billion objects in the museum collections in the United States, many of the objects are in need of some attention. They are at high risk of being lost forever, leaving future generations without such collection to learn from and enjoy. This thesis studies five institutions in the Western New York area. It examines how their preventive conservation practices hold up to standards put forth by museum experts. There are four stages in the research model and they are as follows: (1) identifying threats to collections, (2) substantiating the risk, (3) identifying cost-efficient means of measuring the risk, and (4) developing methods to reduce or eliminate risk. Once a museum has implemented these four stages, the next step is rather simple: monitor and control the principal agents of destruction. By knowing which of these areas are in the most need of the greatest assistance, conservators can make recommendations to help institutions take better care of their collections

2016 Valedictory Address: Emily R. Conn \u2716

Speech given by valedictorian Emily Conn at the 170th Commencement Exercises of the College of the Holy Cross, May 27, 2016.https://crossworks.holycross.edu/valedictory/1003/thumbnail.jp