Improving PV Module Efficiency Through Cooling

The Solarbacks researched and designed a variety of cooling methods that could be used to improve the efficiency of photovoltaics. These cooling methods can be separated into two categories: active and passive methods. The active cooling method of hydraulic cooling and the passive cooling methods of heat sinks (fins), optical coatings, thermosyphons, phase change materials, and thermoelectric generators were all taken into consideration as potential cooling methods. Passive cooling methods were preferred because the use of electricity required for the cooling mechanism would reduce the net electricity and subsequent profit from the panels. Two variations of hydraulic cooling were researched: water spraying and the use of closed channels along the back of the panel. Both water spraying and closed channels along the back of the panel could effectively cool down photovoltaics, but the energy required to pump the necessary amount of water would exceed the additional power generated from cooling. Both variations would also require significant capital cost and would be difficult to scale up. Two passive methods – thermosyphons and phase change materials – were researched but not tested as a final design. Thermosyphons use heat from the panel to boil a working fluid, increased buoyancy moves the fluid upwards where excess heat is released into the environment, condensing the fluid back into a liquid. This starts the process over again. Thermosyphons have been proven to work effectively for concentrated photovoltaic systems; however, the layout of typical solar farms is not conducive for thermosyphons if they utilize a solar tracking system. Chosen phase change materials would have a melting point that is within the operating range of the heated solar panel and would cool the panel through conductive heat transfer from the back of the panel to the phase change material. When put in thermal contact with the panel, the panel’s temperature would not exceed the melting temperature of the material until all of it had melted. This method was disregarded because once the material had melted, the panel would no longer be cooled. Additional passive methods were researched and tested. Ideal optical coatings reflect any solar irradiance that is not used by the panel to produce electricity, however, the coatings researched and tested produced minimal cooling. The coating Solarbacks tested was a thin sheet of mylar (saran wrap). The average cooling produced by the saran wrap was about 2.4oC. However, most of this cooling is thought to be a result of a thermosyphon effect because the saran wrap was elevated off the surface of the panel rather than being directly attached. This elevation likely induced forced convection with the outside air to cool the panel. Fins as a heat sink work by increasing the surface area that heat can be dissipated from. One of the biggest disadvantages to fins is that their efficacy is strongly dependent on ambient conditions. The fins tested by Solarbacks were 1” tall, spaced 1” from each other, and placed on a 1/8” aluminum sheet and attached to the photovoltaic panel using a thermal mastic. The approximate cost of materials per panel would be around $28 when materials are purchased in bulk for a 1/32” thickness extruded fin. Testing showed that fins could cool the panel 14oC during peak temperatures and increase power output by about 5.52Thermal electric generators (TEGs) use electrically dissimilar semiconductors to produce an electric current. When put in thermal contact with the back of the panel, the generator would use any excess heat to produce electricity. The heat TEGs use to produce electricity could help cool the panel to some degree, but their main contribution is the additional electricity they generate. This additional electricity would outweigh the losses due to heating and increase the profitability of each solar panel. If the back of a panel was covered with TEGs and a 20oC temperature difference was maintains for 8 hr. a day in New Mexico, the TEGs would produce an additional 0.778 kWh/day. The biggest disadvantage to using TEGs is the capital cost. Using typical TEG dimensions (40mm*40mm), 536 of them would need to be bought per panel with each TEG costing about$2.92. Larger TEGs could be produced to fit to back of each panel and could reduce this capital cost significantly. Overall, TEGs with fins provides the greatest amount of panel cooling and additional power production. There is an average of a 12.1°C temperature difference along a panel with this solution installed. Using manufacturer data, an estimated 135W can be produced from the TEGs at a 20°C temperature differential along the TEGs. However, when payout for this method is considered, it would take nearly 31 years. Purchasing additional panels that produce the same amount of power as the TEGs would have a payout period of less than 6 years. TEGs with fins at their current cost is not an economic alternative to purchasing more panels despite its cooling and power production capabilities

Speech characteristics of conversational speech tasks

Conversational speech tasks are utilized in research and clinical practice of speech and hearing sciences. Nonetheless, conversational speech is often defined and implemented differently across contexts, which poses a challenge for the interpretation and comparison of data gathered. The purpose of this pilot study is to compare speech characteristics elicited with different speech tasks that have been adopted to elicit conversational speech. Specifically, speech produced during an interview, a topic-driven free conversation, and a Diapix is compared. An interview is a task where one individual (the researcher) leads the conversation by asking the other individual questions. A topic-driven free conversation is conversation that results from an individual (the researcher) asking a specific question intended to create conversational speech, for example the question “What are your plans for the weekend?”. A Diapix is a task based conversational task where partners spot the differences within a set of pictures by speaking with each other. Selected acoustic measures associated with speech timing, articulation, and prosody were examined. Findings suggest that speech acoustic characteristics vary across tasks as well as between individuals. The implication of these results is that it may not be appropriate to be use these tasks interchangeably within clinical or research settings

A Man for All Seasons: Woodrow Wilson, Transatlantic Relations and the War against Militarism

This paper investigates the role of transatlantic Wilsonian values in the entry of the United States in to the First World War. Arguing that the offshore balancing thesis and economic rational are not sufficient to explain US entry and we must engage with Wilsonian explanations to understand this conflict

Design and Preliminary Investigation of Crosslinked Chitosan Sponges for Tailorable Drug Delivery and Infection Control

Musculoskeletal wound infections can be difficult to treat, often resulting in multiple surgeries and increased costs, and can be complicated by antibiotic resistant bacteria. The aim of this study was to use genipin, alone or with poly(n-isopropylacrylamide) (PNIPAM), to crosslink chitosan sponges for a tailorable, degradable local drug delivery system to treat known musculoskeletal pathogens. Lyophilized uncrosslinked, genipin crosslinked, and PNIPAM/ genipin crosslinked chitosan sponges were evaluated in vitro for degradation, antibiotic uptake, elution, biologic activity, and biocompatibility. Crosslinked chitosan sponges exhibited decreased degradation and increased antibiotic uptake and elution. PNIPAM/genipin crosslinked sponges had the highest and prolonged release of antibiotics. Vancomycin and amikacin eluted from all sponges was active against Staphylococcus aureus and Pseudomonas aeruginosa, and did not have significant cytotoxic effects. These results indicate that genipin crosslinked and PNIPAM/ genipin crosslinked chitosan sponges have potential as tailorable adjunctive treatments for infection control, suitable for extended degradation and antibiotic release times

Research on feline in vitro maturation and the cell cycle

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references (leaves 29-32).The feline meiotic cycle is poorly understood. In order to elucidate the events occurring during meiosis in the cat oocyte, a study of the levels of Maturation Promoting Factor (MPF) and MAP Kinase (MAPK), enzymes thought to be necessary to induce oocyte maturation, is important. However, before MPF levels can be studied, a method for maturing feline oocytes in vitro efficiently must be perfected. Furthermore, the information gathered from this study will be beneficial for research on the conservation of endangered feline species and for other reproductive techniques. This study focused on identifying an efficient method of maturing feline oocytes in vitro and observing MPF and MAPK levels at different stages of maturation and after activation in the feline oocyte. A study of the comparative efficiencies of different maturation media was conducted using feline oocytes collected from spayed feline tracts. Three different previously published maturation medium protocols were chosen and compared to determine which produced the highest rate of maturation. As a control, oocytes were put into the base maturation medium without the addition of hormones. The oocytes were incubated for 24 hours in humidified 5% CO2 in air. The oocytes were scored to determine the stage of meiosis they had achieved--germinal vesicle stage, metaphase I, or metaphase II. Only oocytes reaching the metaphase II stage were considered matured. The results of this experiment showed that increasing hormone concentrations in the culture medium increases the rate of feline oocyte maturation. To study the cell cycle and MPF and MAPK activity during meiosis, oocytes from the germinal vesicle, metaphase I, and metaphase II stages of meiosis were collected after maturation in the medium determined to be most efficient, as well as activated oocytes. Activated oocytes were obtained by activating mature oocytes with an ionomycin/cycloheximide treatment. Levels of MPF and MAPK activity at different stages in the feline cell cycle were determined by SDS-PAGE after MPF and MAPK reactions. The results of this study show that MPF and MAPK activities are low at the germinal vesicle stage of meiosis and high at both metaphase I and metaphase II in the feline oocyte. Furthermore, the activity of MPF and MAPK decreases after activation until the cell starts mitotic divisions when the levels start to rise again

Gendered Power: Looking at Mad Men, Power, and Its Limits

This project examines the ways in which power circulates and moves in AMC\u27s show, Mad Men, using Michel Foucault\u27s definitions of power. In this paper, I examine the ways in which the movements of power are different in terms of gender and look at what the show reveals, through its visual narrative and its plot, regarding gender and power in America\u27s late-stage capitalist setting

Fungal and Bacterial Infection Mitigation with Antibiotic and Antifungal Loaded Biopolymer Sponges

Musculoskeletal injuries are some of the most prevalent injuries in both civilian and military populations and their infections can be difficult to treat, often resulting in multiple surgeries and increased costs. In both previous and recent military operations, extremity injuries have been the most common battlefield injuries and many involve complex, open fractures. These extremity injuries are especially susceptible to multiple pathogenic, and sometimes drug resistant, bacteria and fungi. Fungal infections have recently become increasingly problematic in both military and civilian populations and have significantly higher amputation rates than those from bacterial infections. Many of these bacterial and fungal strains adhere to tissue and implanted orthopaedic hardware within wounds, forming biofilms. These problematic, often polymicrobial, infections threaten the health of the patient, but the risk also exists of spreading within hospitals to become prominent resistant infections. Local antimicrobial delivery releases high levels of antimicrobials directly to injured wound tissue, overcoming sub-bactericidal or sub-fungicidal antimicrobial levels present in the avascular wound zones. This research will determine the ability of modified chitosan sponges, buffered with sodium acetate or blended with polyethylene glycol (PEG), to act as short term adjunctive therapies to initial surgical treatment for delivering both antibiotics and/or antifungals for early abatement of infection. The objective of this work was to evaluate both types of modified sponges for in vitro and in vivo material characteristics and device functionality. In vitro analysis demonstrated both the buffered and PEG modified chitosan sponges exhibited increased degradation and functional cytocompatibility. The chitosan/PEG sponges were able to be loaded with hydrophobic antifungals and the sponges released in vitro biologically active concentrations, alone or in combination with the antibiotic vancomycin. Both types of modified sponges exhibited good biocompatibility and slight, but not complete, degradation in an in vivo rat intramuscular degradation and biocompatibility model. In an in vivo bacteria biofilm infection prevention mouse model, vancomycin loaded chitosan/PEG sponges also cleared more bacteria than the unmodified chitosan sponges. These experimental results led to the conclusion that with additional research and in vivo studies, the buffered and PEG blended chitosan sponge local delivery systems exhibit potential for use as adjunctive bacterial or fungal infection prevention therapies to standard surgical treatment of musculoskeletal wounds

An Exploration of How Occupational Therapy Students\u27 and Practitioners\u27 Experiences Studying Abroad Affect Fieldwork and Practice

The purpose of this study was to gain perspective on occupational therapy students and licensed occupational therapists’ perception of how their study abroad experiences affect their skills, specifically in regards to cultural awareness and competency. Completed research related to this topic in occupational therapy consisted of expanding cultural constructs and perspectives, understanding strategies that practitioners utilize when engaging different cultures, and practitioners’ meaning of their lived experiences working in other countries. One’s own perception of culture can change through experience and immersion into a new culture. The need for preparing occupational therapy students to attend to culture and cultural awareness in client-centered practice is evidenced through a review of literature (Murden, Norman, Ross, Sturdivant, Kedia, & Shad, 2008). There is also a need to evaluate the long-term impact of international experience on the individual (Johns, 2010; Mu, Coppard, Bracciano, Doll, & Matthews, 2010). The primary research question of this study was how studying abroad affects occupational therapy students’ and licensed occupational therapists’ perceived skillset in fieldwork and practice. Secondary questions include, what does it mean to have cultural awareness or cultural competence? How do you think this experience has affected your awareness and commitment to cultural competence? How have these new perspectives of cultural competency and awareness affect client-centered practice? The goal is to gain valuable insight into these perspectives. Limits of the research would include the results of the study being biased from the perspectives of educated occupational therapy Elizabethtown College students and graduates and that these perspectives are culturally bound to the participants. Another limit may be that each study abroad experience is unique; this study looks specifically at occupational therapy students’ and occupational therapists’ study abroad experiences and its perceivable applications