LOCAL FOODS PURCHASING IN THE FARMERS\u27 MARKET CHANNEL: VALUE-ATTITUDE-BEHAVIOR THEORY

From farmers’ market booths to kitchen tables, demand for locally-produced foods has increased significantly over the last decade. Yet, despite increasing popularity of local foods, theoretically-based research of this topic has just begun. This study fills this gap in literature and broadens the current research base by utilizing Value-Attitude-Behavior Theory to explore local foods purchasing in the farmers’ market channel. The impact of four values (food novelty, food safety, civic engagement, and environmental concern) on consumers’ attitudes regarding farmers’ market design perceptions, farmers’ market social perceptions, and local foods quality perceptions are examined. In turn, the impact of these attitudes on purchase intention and word-of-mouth communications is explored. A web-based, self-administered survey was used in collecting data from a consumer panel of 485 respondents. Through statistical testing using SPSS, a demographic overview of the sample is provided. Additionally, through the use of AMOS and structural equation modeling, research hypotheses are tested. Data analysis reveals all values significantly impact at least one attitudinal construct. The values of food novelty and food safety had the greatest influence positively impacting attitudes toward farmers’ market design perceptions and local foods quality perceptions. All three attitudinal constructs positively impacted consumers’ word-of-mouth communications regarding the farmers’ market. Additionally, attitudes toward farmers’ market social perceptions and local foods quality perceptions positively impacted consumers’ purchase intention. Consumers’ attitudes toward the quality of the local foods offered at the farmers’ market had the greatest influence on purchase intention and word-of-mouth communications. The study concludes with a discussion of limitations as well as the potential of the limitations to serve as springboards for future research. Implications for local foods producers, farmers’ market managers, and Extension educators working with local foods producers and consumers are presented

Pressure Driven Electronic Band Gap Engineering in Tin(IV)-O,N Compounds

The intrinsic link between long-range order, coordination geometry, and the electronic properties of a system must be understood in order to tailor function-specific materials. Although material properties are typically tailored using chemical dopants, such methods can cause irreversible changes to the structure, limiting the range of functionality. The application of high pressure may provide an alternative “clean” method to tune the electronic properties of semiconducting materials by tailoring their defect density and structure. We have explored a number of optoelectronic relevant materials with promising characteristics, specifically Sn-(O,N) compounds which have been predicted to undergo pressure-mediated opening of their optical band gaps. Tin (IV) oxide (SnO$_2$) is a wide band gap semiconductor that belongs to a class of materials known as transparent conducting oxides (TCO). In SnO$_2$ we have discovered pressure-driven disorder in its rutile structure that may explain the origins of its conductivity. We predict this property to be a universal phenomenon across all rutile-structured materials, and could present a new route for strain engineering meta-stable states in rutile structures that are recoverable to ambient conditions. We have also developed a better understanding of the mechanisms that drive the pressure mediated band gap opening in tin (IV) nitride (Sn$_3$N$_4$). X-ray absorption spectroscopy (XAS) is a multifaceted technique that can help elucidate how the behavior of lighter anion species affects the electronic band structure, structural properties, and vibrational dynamics of a material. In this thesis I will discuss how XAS can be combined together with x-ray diffraction (XRD) and Raman spectroscopy to construct a detailed picture regarding the different atomic species in Sn-(O,N) compounds. One difficulty with building a quantitative description based off of experimental data is that many of these materials are known to have highly kinetically hindered phase transitions. Because of this, they exhibit mixed phasing across a wide range of extreme conditions, leading to severe non-hydrostatic stresses within the system. By utilizing \textit{in situ} CO$_2$ laser annealing, I demonstrate that ground state structures can be accessed, overcoming many of the challenges that have thus far prevented a complete understanding of anion disordering and the role that it plays in a materials electronic properties

Forcing Cesium into Higher Oxidation States via Useful Hard X-ray Induced Chemistry at Extreme Conditions

Recent theoretical work published in Nature Chemistry postulates the existence of cesium in high oxidation states when bonding with fluorine. It is thus predicted to behave as a p-block element (such as xenon) at pressures above 5 GPa. At these pressures, fluorine atoms may bond with the inner p-shell electrons forming CsFn, where n may vary from 2 up to 6; thus the oxidation state of Cs may change up to 6+. My research focused on physically synthesizing these compounds and to verify that, given the right conditions, bonding doesn\u27t only occur with valence electrons, but with the inner p-shell electrons as well, much like what occurs in xenon chemistry. The difficulty of proving this experimentally is that working with fluorine is extremely difficult and dangerous, and has only been studied at high pressure in one earlier study. For the past two years our group has been working on developing a new field of science we call: Useful Hard X-ray Photochemistry. By utilizing the highly penetrating, highly focused, and highly ionizing characteristics of hard x-rays, we can decompose relatively safe and inert solid and liquid samples into simple molecules. We have successfully used our technique to produce O2, H2, N2, Cl2, and most recently F2 in situ within a diamond anvil cell. We have also successfully and safely combusted O2 and H2 into water by creating a segregated mixture of potassium perchlorate and ammonia borate within a diamond anvil cell. We have developed a new method to produce molecular fluorine in situ, giving us a safe mechanism to supply excess fluorine that is available to react with cesium in order to experimentally verify the theoretical prediction of the unexpected stoichiometries of cesium compounds. By using techniques such as x-ray absorption fine structure spectroscopy, x-ray diffraction, and Raman spectroscopy, coupled with our new techniques of in situ hard x-ray photochemistry, we sought to experimentally demonstrate this theoretical behavior of inner shell bonding and open the door to a better understanding of chemical bonding under extreme conditions. This thesis discusses the results of our attempt to synthesize these novel CsFn (n\u3e1) compounds

Synthesis of Strained Metal Nanocrystal Architectures for Energy Conversion Electrocatalysis

Thesis advisor: Chia-Kuang F. TsungThesis advisor: Dunwei WangIn order to understand the lattice strain effect and its relationship to size, shape, composition, and catalytic performance, novel well-defined nanocrystal archetypes were designed and synthesized by taking advantage of wet chemical, seed-mediated (mild) reduction routes developed by our lab. First, the current synthesis challenges are addressed in creating smaller monometallic shape-controlled metal nanocrystals, and novel cuboctopods via a hybrid nanoparticle stabilizer. A look at the relationship between lattice strain and morphology is then shown in a single-component system, where still new features have been observed for the first time by the traditional technique of powder x-ray diffraction. Synthesis methods for differently strained Pd surfaces are described and catalysis by these surfaces is discussed. Finally, studies of the synthesis, characterization, electrocatalytic activity, and restructuring of novel and more sophisticated strained architectures are presented: core-island-shell nanocrystals, phase-segregated nanoboxes, island nanoframeworks, and core-sandwich-shell nanoparticles. Lattice strain and composition effects were studied in carbon monoxide, small alcohol, and formic acid electrocatalytic oxidations as well as in oxygen reduction, the latter of which, governs the commercial viability of automotive fuel cells, a sustainable energy and zero-emission technology. Here it is demonstrated how a tunable thickness of Ni sandwich layers can be used to improve catalytic performance by increasing lattice strain on the Pt surface. The sandwich archetype offers a new platform for the investigation of lattice strain and could be a promising, industrially relevant, catalyst design concept, to help address the need for a more sustainable energy future. The results help paint a new picture of catalysis by metal nanocrystals; one which brings lattice strain to the forefront of the discussion, as an important parameter for further study and for use in developing higher-performing catalysts.Thesis (PhD) — Boston College, 2015.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Chemistry

Discovery of a nanodiamond-rich layer in the Greenland ice sheet

We report the discovery in the Greenland ice sheet of a discrete layer of free nanodiamonds (NDs) in very high abundances, implying most likely either an unprecedented influx of extraterrestrial (ET) material or a cosmic impact event that occurred after the last glacial episode. From that layer, we extracted n-diamonds and hexagonal diamonds (lonsdaleite), an accepted ET impact indicator, at abundances of up to about 5!106 times background levels in adjacent younger and older ice. The NDs in the concentrated layer are rounded, suggesting they most likely formed during a cosmic impact through some process similar to carbon-vapor deposition or high-explosive detonation. This morphology has not been reported previously in cosmic material, but has been observed in terrestrial impact material. This is the first highly enriched, discrete layer of NDs observed in glacial ice anywhere, and its presence indicates that ice caps are important archives of ET events of varying magnitudes. Using a preliminary ice chronology based on oxygen isotopes and dust stratigraphy, the ND-rich layer appears to be coeval with ND abundance peaks reported at numerous North American sites in a sedimentary layer, the Younger Dryas boundary layer (YDB), dating to 12.9 0.1 ka. However, more investigation is needed to confirm this association

Seasonal speedup of a Greenland marine-terminating outlet glacier forced by surface melt–induced changes in subglacial hydrology

Peer reviewedPublisher PD

Mechanisms of apoptosis sensitivity and resistance to the BH3 mimetic ABT-737 in acute myeloid leukemia

SummaryBCL-2 proteins are critical for cell survival and are overexpressed in many tumors. ABT-737 is a small-molecule BH3 mimetic that exhibits single-agent activity against lymphoma and small-cell lung cancer in preclinical studies. We here report that ABT-737 effectively kills acute myeloid leukemia blast, progenitor, and stem cells without affecting normal hematopoietic cells. ABT-737 induced the disruption of the BCL-2/BAX complex and BAK-dependent but BIM-independent activation of the intrinsic apoptotic pathway. In cells with phosphorylated BCL-2 or increased MCL-1, ABT-737 was inactive. Inhibition of BCL-2 phosphorylation and reduction of MCL-1 expression restored sensitivity to ABT-737. These data suggest that ABT-737 could be a highly effective antileukemia agent when the mechanisms of resistance identified here are considered

Hyperthermia, radiation and chemotherapy: the role of heat in multidisciplinary cancer care.

The compelling biologic basis for combining hyperthermia with modern cancer therapies including radiation and chemotherapy was first appreciated nearly half a century ago. Hyperthermia complements radiation as conditions contributing to radio-resistance generally enhance sensitivity to heat and sensitizing effects occur through increased perfusion/tumor oxygenation and alteration of cellular death pathways. Chemosensitization with hyperthermia is dependent on the particular mechanism of effect for each agent with synergistic effects noted for several commonly used agents. Clinically, randomized trials have demonstrated benefit including survival with the addition of hyperthermia to radiation or chemotherapy in treatment of a wide range of malignancies. Improvements in treatment delivery techniques, streamlined logistics, and greater understanding of the relationship of thermal dosimetry to treatment outcomes continue to facilitate wider clinical implementation. Evolving applications include thermal enhancement of immunotherapy, targeted drug delivery and application of principals of thermal biology towards integration of thermal ablation into multimodality oncologic care