Fabrication of cell culture scaffolds using micro/nanotechnologies to study the attachment and alignment of smooth muscle cells

This dissertation elaborates the design and fabrication of in vitro cell culture scaffolds using microfabrication and electrostatic layer-by-layer self-assembly (LbL) technologies, and develops the so-called layer-by-layer lift-off (LbL-LO) technique to control surface topography, surface properties, and underlying architectures of the scaffolds. Smooth muscle cells were cultured on the fabricated scaffolds with gelatin, fibronectin, and polyelectrolytes (PSS, PDDA, PAH, and PEI) as surface materials, multilayer polyelectrolytes as architectures, deposited in strip- and square-patterns. It was found that the exposed surface materials, which have different charge, hydrophobicity, and chemical structure (e.g., amino acid sequence), affect the adhesion of smooth muscle cells. Cells attached and grew on negatively-charged gelatin, PSS, and acid-treated glass surfaces rather than on positively-charged PDDA and PAH surfaces. The cell-adhesive proteins gelatin and fibronectin improve the attachment and further growth of smooth muscle cells, and cells attached to these surfaces showed more natural morphology than on PSS-coated surfaces. In addition, the underlying architectures of the polyelectrolyte thin films also significantly influence the cell morphologies and attachment. Cells on thicker nanofilms (20-bilayer) showed more elongated and spread-out morphology than on the thinner ones (e.g., 2-bilayer). Cells cultured on the gelatin- and fibronectin-coated strip patterns showed aligned patterns along the main axis of the strips. It was observed cells on 60μm wide strips had better alignment than on the 120μm strips. The experimental results indicate that the LbL-LO technique is an efficient method to fabricate in vitro cell culture scaffolds with precise control of the surface properties and topography in three dimensions, and therefore, to study the cell behavior. The results of study suggest that a combination of micro/nanotechnologies for biosurface engineering has great potential in the application of tissue engineering and other related areas

1, 4-Dioxane biodegradation at low temperatures in Arctic groundwater samples

1,4-Dioxane is an emerging groundwater contaminant and a probable human carcinogen. Its biodegradation was investigated in microcosms prepared with groundwater and soil from an impacted site in Alaska. In addition to natural attenuation conditions (i.e., no amendments), the following treatments were tested: (a) biostimulation by addition of 1-butanol (a readily available auxiliary substrate) and inorganic nutrients; and (b) bioaugmentation with Pseudonocardia dioxanivorans CB1190, a well-characterized dioxane degrading bacterium, or with Pseudonocardia antarctica DVS 5a1, a bacterium isolated from Antarctica. Biostimulation enhanced the degradation of 50 mg L-1 dioxane by indigenous microorganisms (about 0.01 mg dioxane d-1 mg protein-1) at both 4 and 14°C, with a simultaneous increase in biomass. A more pronounced enhancement was observed through bioaugmentation. Microcosms with 50 mg L -1 initial dioxane (representing source zone contamination) and augmented with CB1190 degraded dioxane fastest (0.155 +/- 0.038 mg dioxane d-1 mg protein-1) at 14°C, and the degradation rate decreased dramatically at 4°C (0.021 +/- 0.007 mg dioxane d-1 mg protein-1). In contrast, microcosms with DVS 5a1 degraded dioxane at similar rates at 4 and 14°C (0.018 +/- 0.004 and 0.015 +/- 0.006 mg dioxane d-1 mg protein-1, respectively). DVS 5a1 outperformed CB1190 when the initial dioxane concentration was low (500 microg L-1). This indicates differences in competitive advantages of these two strains. Natural attenuation microcosms also showed significant degradation over 6 months when the initial dioxane concentration was 500 microg L-1. This is the first study to report the potential for dioxane bioremediation and natural attenuation of contaminated groundwater in sensitive cold-weather ecosystems such as the Arctic

Oxidation barriers prepared by electrochemical procedures

Predkladaná bakalárska práca sa zaoberá popisom vzniku samo organizovaných vrstiev oxidu hlinitého, technológiou výroby týchto vrstiev a rozvádza možnosti tejto technológie smerom ku príprave oxidačne odolných vrstiev pre vysoko teplotné aplikácie. Práca je koncipovaná ako úvodná štúdia problematiky tvorby a využitia a usporiadaných poréznych oxidických vrstiev na hliníku s vyhlasom na ďalšie experimentálne spracovanie tejto témy v rámci magisterského štúdia.The presented bachelor thesis deals theoretically with use of anodization procedures for preparation of self-organized porous oxide layers on aluminium. The techniques leading to different pore structures are summarized and the use of porous anodic alumina in various applications of nanotechnology are mentioned. The thesis is composed as initial entry-level theroretical study for prospective experimental work in the field of porous anodic alumina.

The Impact of Social Services on the Utilization of Health Care Services

Indiana University-Purdue University Indianapolis (IUPUI)The unnecessary medical care causes a heavy financial burden for the patients themselves and the society, and they also negatively impact the quality of medical care. An estimated 13% to 27% of ED visits in the United States could be managed in physician offices, clinics, and urgent care centers, saving $4.4 billion annually, and 26 percent of hospitalizations were potentially avoidable at a cost of$5.6 billion in 2005. If we can help people become more aware of health care services, it could be a potentially effective way to reduce emergency service overuse. we focused on mental health service and social work service as intervention variable, preventable ED visit, preventable ED visit due to mental health problem and hospitalization due to mental health problem as outcomes to determine the impact of specific social service on utilization of specific health care service adjusting for other characteristics of patients (demographic and utilization history information). The data which involved 24074 patients was provided from and managed by the Regenstrief Institute. The date of having the specific service and the frequency of using the specific health care service per year from 2011 to 2014 for each patient was recorded as well as the baseline information including gender, age, race, primary care visit per year before 2011, ACG risk score at 2011, ED visit per year before 2011. For each of preventable ED visit, preventable ED visit due to mental health problem and hospitalization due to mental health problem, we fitted a multiple linear regression model to ascertain the effects of mental health service and social work service adjusted for the baseline information. There was a significant relationship between preventable ED visit & mental health service, hospitalization due to mental health problems & mental health service, as well as hospitalization due to mental health problems & social work service. We found that in most situation, social services were positively associated with health care service. But in the second model which described the impact of mental health service on utilization of hospitalization due to mental health problem, receiving one mental health service can reduce the utilization of hospitalization due to mental health problem, which is as our expectation. According to our study, appropriate amount of services appears helpful on reducing the overuse of ED and hospitalization due to mental health problem. However, people who overused ED or hospitalization in the past were also more likely to be frequent service users, and they tended to continue overuse ED or Incur more hospitalization. There is a group of people who overuse ED or hospitalization without having any service. ED or hospitalization may be their first choice because of their financial condition or other factors, which makes them have no interest to take services

Research on the Relationship between Cash Holding and Business Credit in the View of Supply Chain

This paper analyzes the relationship between corporate cash holdings and commercial credit from the perspective of supply chain, selects 1162 listed companies from 2017 to 2021 as sample objects, analyzes the impact of corporate commercial credit on cash holdings, and discusses the regulatory role of regional financial development level on this impact. The final result shows that there is a significant positive correlation between business payables, i.e. business credit obtained by enterprises, and cash holdings; There is a significant negative correlation between enterprise receivables, i.e. business credit provided by enterprises, and enterprise cash holdings

Research on the Relationship between Cash Holdings and Commercial Credit in Zhejiang Manufacturing Industry: A Supply Chain Perspective

In the manufacturing supply chain, there is a tripartite relationship between upstream suppliers, midstream manufacturing enterprises and downstream customers. The supply chain environment is changing from competition to cooperation. Based on the perspective of supply chain, the study of the impact of cash holdings and business credit of manufacturing enterprises in Zhejiang Province is conducive to a comprehensive review of the relationship between cash holdings and business credit of manufacturing enterprises in Zhejiang Province, and enhance their competitive position in the supply chain. It is found that the cash holding level of manufacturing enterprises in Zhejiang Province is negatively correlated with the occupation of the commercial credit of upstream suppliers, positively correlated with the occupation of the commercial credit of downstream customers, and positively correlated with the occupation of the overall commercial credit of the supply chain