Anaerobic bioassay of methane potential of microalgal biomass

Yen, Hong-wei Clemson University 2004 해외박사(DDOD)

This study was undertaken to investigate the feasibility of using anaerobic digestion as a technique to recover solar energy embodied in excess algal biomass production harvested from Clemson University's high rate algal based Partitioned Aquaculture System (PAS) as an energy source to support PAS operations. In this study, four different organic substrates were loaded to anaerobic digesters in eight experimental trials, to ascertain the optimal combination of operational variables and effect of algal, or modified algal substrate upon methane production rate. The four substrates used in this study were: (1) a synthetic feedstock consisting of molasses and dog food, (2) a commercially obtained, readily degradable algal biomass (Spirulina ) in dry form, (3) PAS harvested and dewatered algal sludge, and (4) algal biomass blended with shredded waste paper or molasses as a carbon supplement for the adjustment of algal C/N ratio. Eight experimental trials using combinations of the four substrates were conducted in 15 liter digesters to investigate the effects of controlled digester parameters upon digester performance. Digesters operating at 20 days HRT, mesophilic digestion (35°C), and twice per day mixing at maximal loading rates produced maximal methane gas using PAS algal sludge. However, under these conditions overall methane production was less than 1000 ml CH4/l day. This low level of energy recovery from the fermentation of algal biomass (alone) is not energetically or economically favorable. Co-digestion of algal sludge and waste paper was investigated as a way to increase methane production. The data obtained from these trials suggest an optimum C/N ratio for co-digestion of algal sludge and waste paper in the range of 20--25/l. A balanced C/N ratio along with the stimulated increase in cellulase activity is suggested as likely reasons for increased methane production seen in co-digestion of algal sludge and waste paper. Yeast extract addition to anaerobic digesters was also seen to be beneficial to the process resulting in an increase in methane production. Similar performances in digesters fed Spirulina plus paper and yeast extract plus paper suggests that yeast extract served a similar function as Spirulina in anaerobic digestion. Digestion of algal sludge alone was not energetically or economically favorable. However, co-digestion of algal sludge and paper improves the methane production rate. At 4 g VS/l/day loading rate with 50% paper fraction, methane production rate at 10 days HRT was 1170 +/- 75 ml CH4/l day. A maximum methane production rate was observed at 10 days HRT with a combined paper and algal sludge loading of 5 g VS/l/day (60% paper fraction), yielding 1607 +/- 17 ml/l. (Abstract shortened by UMI.).

Field evaluation of the immunocontraceptive GonaCon(TM) in reducing eastern gray squirrel fecundity in urban areas

Pai, Murali Clemson University 2009 해외박사(DDOD)

The purpose of this study was to evaluate the immunocontraceptive GonaCon(TM) in reducing fecundity in Eastern gray squirrel (EGS) (Sciurus carolinensis ) in urban areas. Using a modified box trap design, 317 EGS were captured during four trapping sessions on a 5.66 ha site on Clemson University's main campus. EGS were handled using a restraint cone and sexed, weighed, ear-tagged and implanted with a microchip at the nape of the neck on all "original" captures and later identified in subsequent captures as "recaptures." Blood samples and morphometric data were obtained on EGS before the immunocontraceptive GonaCon(TM) was administered by injection during three trapping sessions to 33 EGS (17m, 16f) in trapping session 1 (TS1), 23 (14m, 9f) in trapping session 2 (TS2), and 11 (8m, 3f) in trapping session 3 (TS3) at a dosage rate of 0.4 ml containing 400 ig of GnRH-blue protein conjugate intramuscularly in the thigh. Control EGS were given a sham injection containing 0.4 ml saline- AdjuVac(TM) during the three trapping sessions: 22 EGS (16m, 6f) in TS1, 20 (12m, 8f) in TS2, and 8 (4m, 4f) in TS3. In the last trapping session (TS4) 35 EGS were necropsied to evaluate histological changes in testes and ovaries as potential metrics of GonaCon(TM) efficacy and to determine its potential side effects. EGS density on the study area was estimated to be 9 +/- (2.89) EGS/ha, based on the Lincoln-Peterson model. There were no significant differences in body weights of treated and control EGS by TS3 (p = 0.40), or testosterone (p = 0.32) and progesterone (p = 0.68) levels. However, there were significant differences in antibody titers between treated and control EGS by TS3 in both males and females active antibodies seen in the treatment group (chi2 = 5.656, df = 1, p = 0.017). There were highly significant differences in scrotal size of treated and control males with a reduction in scrotal size being observed in treated males (t = 10.14, df = 8, p = 0.001). There were marked histological changes in treated EGS males and no observable histological changes in treated EGS females. Although there were no serious side effects to the vaccine; 6 EGS developed injection site abscesses. GonaCon(TM) may be a potential tool to manage EGS overabundance in urban areas, but additional research is needed.

Development of a computer model to predict oxygen, inorganic carbon and inorganic nitrogen concentrations in the partitioned aquaculture system

Schwartz, Gregory Clemson University 2004 해외박사(DDOD)

A finite element, finite difference simulation model utilizing deterministic and empirical submodels capable of predicting time dependent dynamics of oxygen, inorganic carbon and inorganic nitrogen concentrations within Clemson University's Partitioned Aquaculture System (PAS) was developed, calibrated, and a sensitivity analysis was carried out. The model's dynamic behavior was calibrated and validated using three years of data (1999--2001) obtained from operation of a two-acre PAS unit and five years of data (1997--2001) from operation of six 1/3-acre PAS units. Calibration of system parameters revealed half saturation coefficients for light inhibition for photosynthesis (Ks PAR) and oxygen inhibition for sediment demand (Ks other). Ks PAR varied as a function of particulate organic carbon (POC) while Ks other may shift from a value of 4 to 8 for new ponds to a value of 0.5 to 1 for aged ponds. System oxygen concentration, pH and total ammonia nitrogen (TAN) concentration was predicted at three feed levels, 150, 200 and 300 Lb/acre-day, for four secchi disk visibilities (SDV), 5, 10, 15 and 20 cm and four water column total alkalinities, 1.5, 2, 3 and 4 meq/L. Predicted peak maximum oxygen concentrations in the algal raceway decrease as feed increases (from 150 to 300 Lb/A-day) and as SDV increases (from 5 cm to 20 cm). Simulated maximum oxygen output range from 21 to 27 mg/L with SDV of 5 cm falling to 17 to 19 mg/L with SDV of 20 cm for 150 Lb/A-day feed level, from 22 to 23 mg/L with SDV of 5 cm falling to 15 mg/L with SDV of 20 cm for 200 Lb/A-day feed level and 16 mg/L with SDV of 5 cm falling to 10 mg/L with SDV of 20 cm for 300 Lb/A-day. Daily minimum oxygen concentrations decrease slightly as feed level increases, from 2 to 4 mg/L at 150 Lb/A-day (5 and 20 cm SDV) to 1.5 and 3 mg/L at 200 Lb/A-day (5 and 20 cm SDV) to 0.5 and 1 mg/L at 300 Lb/A-day (5 and 20 cm SDV). Total alkalinity did not impact oxygen concentration unless the system was carbon limited. Examination of the oxygen mass balance suggested that net photosynthesis increased from 190,000 g 02/2A-dayat 20 cm to 280,000 g O2/2A-day at 5 cm SDV and that "other demand" increased from 110,000 g O2/2A-day (150 Lb/A-day feed) to 225,000 g O2/2A-day (300 Lb/A-day). Fish respiration values suggested that at high feed levels fish respiration was inhibited due to low dissolved oxygen. (Abstract shortened by UMI.).

Factors that affect alumni giving at a southeastern comprehensive university

Conner, Deborah Kay Clemson University 2005 해외박사(DDOD)

Decreases in funding levels for higher education on the state and national levels continue to put pressure on institutions to raise more private dollars to meet financial goals. In response to this, institutions of higher education need to better understand the characteristics that effect alumni and whether or not they will donate to their alma mater. Alumni giving is the most consistent fundraising income generated by colleges and universities, usually through annual fund drives. This study looks at five categories of variables including: demographic, undergraduate involvement, alumni involvement, educational gains (value), and alumni loyalty. Based on an exhaustive review of research in the area of alumni giving and the factors that may predict alumni giving, a survey was designed to determine which of these most influences an alumni status of donor or non-donor. A comprehensive structural equation model has been developed utilizing LISREL 8.71. The model and survey can be easily adapted to other colleges or universities with a need to understand alumni giving to their institution and how they can increase it. The results show that alumni studied are more likely to have been involved as undergraduates, express feelings of institutional loyalty, feel they received value from their educational experience, have graduated more recently, currently live in close proximity to the their alma mater, and have a higher household income. Alumni non-donors are more likely to donate to other charitable organizations, have graduated earlier in the university's history, and live further away from the campus. There was no difference found between donors and non-donors in the number of years they attended college, or in alumni involvement.

A Model of Understanding Choice of University by International Students: A Two-case Study

Jiang, Shuiping ProQuest Dissertations & Theses Clemson University 2020 해외박사(DDOD)

Students from all over the world who study in the United States contribute to the economy, participate in scientific and technical research, foster a diverse campus environment, enrich the learning environment with cultural perspectives, and help prepare domestic students for global careers, which often lead to long-term business relationships. However, in the United States, higher education institutions are facing ever-increasing challenges in enrolling international students. In the past three years, many universities faced difficulties in increasing or maintaining international student enrollment, forcing colleges and universities to search for the most effective ways to attract international students with limited resources. This is particularly true for those Master’s colleges and universities with limited marketing funding for international student enrollment. By conducting surveys and interviews at two universities, the study examined university administrators’ perceptions of university-related strategies of international student enrollment, the most influential factors in international student college choice based on student perceptions, and the degree to which student and administrator perceptions converge and diverge in relation to enrollment strategies and student college choice. This study is expected to provide a tool and knowledge for university policy makers and administrators to adjust appropriate recruiting strategies under limited budget in order to optimize resource outputs.

How Thai students use word processors to approximate Edited American English

Gubtapol, Kobkhan Clemson University 2002 해외박사(DDOD)

This qualitative case study's purpose was to explore how Thai students edit their writing using word processing programs as they seek to approximate Edited American English (EAE) in American colleges. The research questions were as follows: (1) How or in what ways does a computer, with a word processing program, help or hinder Thai students as they produce texts that approximate Edited American English (EAE)? (2) What editing strategies do Thai students use with word processors and how?. Traditional qualitative data collection methods were used such as case study, participant observations, ethnographic interviews, and document analysis (LeCompte & Schensul, 1990). Additionally, follow-up, open-ended surveys based on the preliminary case study were administrated to 33 Thai students at a research university. Data from these resources were identified, coded, tallied, categorized and summarized according to Pennington's (1996) factors that contribute to the effectiveness of writing with word processing programs. The study revealed that use of word processing programs helped Thai students approximate EAE. The word processing strategies that Thai students learned aided them with capitalization, singular and plural forms, subject/verb agreement, use of periods, and commas. Basic word-processing features provided such help: the red line as well as the spell check feature for spelling errors, the green line for grammar errors relate to end punctuation and apostrophe, and auto correction for misspelled words and capitalization errors. Implications are that Thai students entering American colleges may benefit from more extensive instruction in using word processing programs to approximate EAE. It also suggests that writing instruction for English as a Foreign Language (EFL) students may be enhanced by explicitly introducing students to word-processing tools that support their capacities to approximate EAE. Much more research is needed on ways to build word-processing programs and EFL Writing Programs for diverse language users from various nationalities as they struggle to become fluent with EAE.

Microeconomic studies in higher education

Julian, Reynaldo Hernandez Clemson University 2005 해외박사(DDOD)

This dissertation uses institutional data from Clemson University to answer economic questions. The first chapter, "Merit-based Scholarships and Grade Inflation in Higher Education" addresses whether grades are affected by the South Carolina's LIFE scholarship. The scholarship currently pays eligible students $5,000 to maintain a 3.0 GPA. These students respond to this incentive by working harder and as a result their grades increase significantly. The grades of those students who are not eligible, however, do not increase, suggesting that merit-based scholarships do not aggravate grade inflation. This paper measures how one merit-based scholarship affects grades and separates that effect into grade inflation and increased effort. The second chapter, "Transfer Students and College Quality", compares students who transfer to Clemson University from different institutions. Given their performance at Clemson, the study can evaluate which characteristics make some schools more successful than others at imparting human capital. The results can be used by students when choosing a school and by universities when evaluating transfer applicants. This paper examines how students that transfer credit for an introductory-level course perform in a subsequent intermediate-level course. We find that the student attributes, not school characteristics, explain most of the variation in grades. Of the college characteristics, selectivity, tuition, and the percentage of professors with Ph.D.'s are the best predictors of school quality. The third chapter, "Time of Day and Academic Performance: Does Class Time Affect Students' Grades?", looks at how student performance varies throughout the school day. College students generally like late nights, so one would expect their performance early in the day to be worse. The study shows that to be the case, and that students perform better in later classes and when their first class in a day is later. This paper looks at the relationship between the time of a class and performance, controlling for observable student characteristics. The literature in psychology has recognized the effect of time of day on performance, particularly that adolescents' performance is weaker in early hours. This study supports that literature by showing that the quality of academic performance in Clemson University improves throughout the school day. (Abstract shortened by UMI.).

The effects of a professional development workshop on faculty integration of technology in the university classroom

Reimer, Mary Steffan Clemson University 2002 해외박사(DDOD)

The purpose of this interpretivist study was to explore the effects of a professional development workshop on faculty integration of technology in the university classroom. The research questions guiding this study were (1) Does participating in a Teaching and Technology Institute impact how and if faculty integrate technology into the classroom? (2) Does preferred learning style impact how faculty integrate technology into the classroom?. Semi-structured interviews, observation participation, a technology and professional development questionnaire, and Kolb's Learning Style Inventory were used to gather data. Data analysis was concurrent with data collection, and final themes were validated with four participants. The results indicated that the overarching theme of this study was frustration and the major theme was technology self-efficacy. Bandura's Theory of Self-Efficacy as it relates to technology use was the best explanation for how and why university faculty integrate technology into the classroom. Learning style did have a minor effect on how faculty integrated technology, but learning style could not explain all of the differences in technology use. The vast majority of participants exhibited low levels of technology self-efficacy, which related to their lack of use of technology in the classroom. All of the participants commented on the frustration they experienced when trying to use technology. The major theme of self-efficacy was developed from the domains of mastery experiences, peer role models, positive and negative reinforcement, and stress.

An exploratory study of travel constructs in mature tourism

Wang, Yawei Clemson University 2005 해외박사(DDOD)

The purpose of this study was to explore the nature of mature tourism via the aging theoretical framework of Selective Optimization with Compensation (SOC). Older adults who attended Lifelong Learning classes at Clemson University and Furman University, South Carolina in the spring of 2004 were chosen to participate in this study. Five general categories of independent variables were studied to determine their potential influence on mature respondents' travel intention: socio-demographics (i.e., age, gender, length of residence at current home, length of residence in the Upstate of South Carolina, marital status, race, education, employment status, and annual household income), travel psychographics (i.e., travel motivation and constraint factors), quality of life (i.e., global life satisfaction and self-perceived health), and travel behavior variables (i.e., past travel experience, number of leisure trips taken last year, number of days away from home on leisure trips, satisfaction with last leisure trip, satisfaction with leisure trips in general, travel information sources, travel planners, trip companions, and destination attributes), and the SOC processes (i.e., elective selection, loss-based selection, optimization, and compensation). These five categories of variables were found interrelated. This study also identified important predictors of mature respondents' intention to travel within one year and five years, as well as parameters that influence the SOC processes. The results of this study profiled socio-demographic, psychographic, and travel behavior characteristics of mature travelers.

Supercritical fractionation of petroleum pitches: Experiment and prediction

Zhuang, Shuzhong Clemson University 2001 해외박사(DDOD)

Previous work at Clemson has shown that supercritical extraction (SCE) can be used to produce liquid crystalline (i.e., mesophase) pitches of excellent quality for use as starting materials for high-performance carbon products. However, to date the full potential of such extraction processes for manipulating the molecular composition of pitches for a desired end use has yet to be realized. The goals of this project were twofold: (1) to develop equations of state (EoSs) applicable to pitch-solvent systems and to the multicomponent pitch mixtures themselves; (2) to investigate the potential of stagewise SCE for producing fractions suitable for analytical characterization studies. A thermodynamic model that incorporates the SAFT EoS, the MWD of the feed pitch, and mathematically generated pseudocomponents was developed for predicting phase compositions and extraction yields for the SCE process. Our model uses two binary parameters, which were determined by fitting a limited set of isothermal LLE data for pitch-solvent systems. SAFT was subsequently used with these parameters to successfully predict solvent-phase compositions at other extraction conditions. As originally developed, SAFT cannot predict the existence of mesophase. Thus, in collaboration with Hurt and co-workers at Brown University, we created a modification of SAFT for these liquid crystalline pitches (i.e., SAFT-LC). Using only three binary parameters, SAFT-LC was successfully used to model both the SCE step, where solvent-pitch interactions dominate, and the mesophase formation step in the dried pitch product, where pitch-pitch interactions are significant. A stagewise fractionation technique employing sequential, single-stage SCE was used to fractionate the heaviest portion of a petroleum pitch by operating at higher pressures in the LLE region. The pressure was sequentially reduced in each stage so as to precipitate out ∼5 wt % of the feed pitch in each stage. Five fractions comprising the heaviest 28.8 wt % of the feed pitch were obtained. Although analytical characterization (e.g., C/H ratio, softening point, and DRIFTS) indicated that the pitches were being separated according to molecular weight, more quantitative molecular information proved difficult to obtain, even after the heaviest three fractions were hydrogenated by Birch reduction so that GPC could be used.