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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Is there a relation between the cost of debt and environmental performance? An empirical investigation of the U.S. Pulp and Paper Industry, 1994-2005.

Schneider, Thomas Ervin January 2008 (has links)
This study shows an economically significant relation between a firm’s environmental performance and its cost of debt. Firms that have poor environmental performance will face future environmental liabilities related to compliance and clean-up costs due to increasingly strict environmental laws and regulations. Under current U.S. law, environmental liabilities can impair the value of fixed assets, as environmental claims often take precedence over the claims of creditors. Thus, future environmental liabilities are of particular concern to creditors. Previous accounting research has shown that a firm’s market value of equity is significantly affected by its environmental performance. However, the same has yet to be shown for a firm’s cost of debt capital. This study focuses on a sample of U.S. pulp and paper firms. The results imply that the market applies an ‘environmental risk’ premium of thirty-eight basis points to the cost of debt capital for the average public firm in the U.S. pulp and paper industry, based on its environmental performance. Environmental performance is measured using the annual toxic release inventory of the United States Environmental Protection Agency. It is a measure of the amount of toxic chemicals released to land, air and water by a firm’s operating facilities. This paper adds to the literature, providing evidence that environmental performance is a value relevant measure with regards to creditors. Thus, recent calls in the United States for greater cooperation between the Securities and Exchange Commission and the Environmental Protection Agency should be addressed. These calls are for the reporting, on a firm-wide basis, of quantifiable data that is already required by the Environmental Protection Agency but is not typically available in detail in firms’ reports to investors.
232

Offline Programming of Robots in Car Seat Production

Al Hayani, Musab January 2013 (has links)
Company Purtech in Dals-Ed manufactures molded polyurethane (PUR). Examples of products that include polyurethane are car seats. Robots are used to fill the molds with PUR and to apply the release agent (wax) in the empty molds. Turning from online programming into a graphical offline programming of release agent spraying robots is going to simplify the process by: Applying less of release agent to avoid polluting environment, to produce an easier removal of moulds, for the sake of homogeneous moulds and for economical saving in the cost of release agent Adaption of spraying paths to variation in production speed. Programming of complex spraying trajectories to deal with sharp geometrical subsurface Decreasing onsite programming time (when program a new workpiece or modify an old one); so that robots would be free for production. While turning into offline programming brought the challenges of: Impact of variation in the production speed Lack of 3D models of workcell’s equipments Robot joint configuration when paths and robtargets are in move. Physical Joint limits, Singularities & Reach limits Collisions within the cell space. At the end, the following objectives are successfully met: Adaption of spraying programs to variation in production speed by developing and embedding a method in those programs. Graphical offline generation of spraying trajectories and optimization of those trajectories to the Purtech condition of spraying allowed time for each carrier. Simulation of release agent spraying process; and producing of a well structured RAPID program that reflect the simulated process.
233

Binding & Release of Biomolecules from Hyaluronic Acid Macrogels with Cetylpyridinium Chloride as a Model Surfactant

Sandell, Sara January 2011 (has links)
The purpose of this master thesis project was to investigate the penetration ofbiomolecules into hyaluronic acid (HA) macrogels. The investigations were performedboth in the presence and in the absence of the non-biodegradable surfactantcetylpyridinium chloride (CPC), which earlier has proved to form a micelle-rich shellat the gel surface. In this work investigations were performed to see if properties ofthe biomolecules used, such as size and charge, had any impact on the binding to theHA gels both with and without CPC. The biomolecules used were the proteinscytochrome c, lysozyme, hemoglobin and myoglobin and the polysaccharide dextranof different molecular weights and labeled with fluorescein isothiocyanate.Cetylpyridinium chloride was used as a non-biodegradable model surfactant for abiodegradable betaine ester surfactant. The cetylpyridinium chloride was thereforeserving well when performing control studies for the biodegradable betaine ester,because the two possesses similar properties. Investigations involving the betaineester surfactant was not included in this master thesis project. Also release studiesinvolving the labeled dextran and some of the proteins were performed in thepresence and absence of cetylpyridinium chloride.The binding of CPC to HA was investigated briefly as well as the microstructure ofHA gels saturated with CPC by means of small-angle X-ray scattering, SAXS, atdifferent salt concentrations. The microstructure-investigations indicated that at 10mM NaCl a cubic ordered phase with space group Pm3n was achieved. When the saltconcentration was increased to 40 mM the microstructure was altered to a clearface-centered cubic (FCC) structure. When increasing the NaCl concentrationfurther, to 150 mM, indication of an unordered micellar phase could be seen.Cytochrome c and lysozyme transport into HA gels, to which CPC had bound in anearlier step, could be registered using UV-VIS spectrophotometry. Indications showedthat CPC and cytochrome c was distributed to different parts of the gel frommicroscope pictures taken of the cross-section of gel samples at different time.From release experiments performed with fluorescein isothiocyanate-dextran noconclusions could be drawn on how the different molecular weights of dextranaffected the rate and extent of the amount substance released. Neither could theinfluence of CPC be elucidated. This since the extent of released amounts exceeded100 % for many samples and the duplicate samples investigated showed differentbehavior.The transport of cytochrome c, myoglobin and hemoglobin into HA gels with andwithout beforehand treatment with CPC was evaluated qualitatively. The transportinto gels treated with CPC was successful and complete with cytochrome c andmyoglobin at lower degree of binding but was limited for the bigger proteinhemoglobin. When investigating the release of cytochrome c, myoglobin andhemoglobin from HA gels the extent of released substance was lower with CPCpresent in the solution compared without CPC present. Also some indicationsshowed that the bigger size of hemoglobin affected the rate of release from the gel.
234

Is there a relation between the cost of debt and environmental performance? An empirical investigation of the U.S. Pulp and Paper Industry, 1994-2005.

Schneider, Thomas Ervin January 2008 (has links)
This study shows an economically significant relation between a firm’s environmental performance and its cost of debt. Firms that have poor environmental performance will face future environmental liabilities related to compliance and clean-up costs due to increasingly strict environmental laws and regulations. Under current U.S. law, environmental liabilities can impair the value of fixed assets, as environmental claims often take precedence over the claims of creditors. Thus, future environmental liabilities are of particular concern to creditors. Previous accounting research has shown that a firm’s market value of equity is significantly affected by its environmental performance. However, the same has yet to be shown for a firm’s cost of debt capital. This study focuses on a sample of U.S. pulp and paper firms. The results imply that the market applies an ‘environmental risk’ premium of thirty-eight basis points to the cost of debt capital for the average public firm in the U.S. pulp and paper industry, based on its environmental performance. Environmental performance is measured using the annual toxic release inventory of the United States Environmental Protection Agency. It is a measure of the amount of toxic chemicals released to land, air and water by a firm’s operating facilities. This paper adds to the literature, providing evidence that environmental performance is a value relevant measure with regards to creditors. Thus, recent calls in the United States for greater cooperation between the Securities and Exchange Commission and the Environmental Protection Agency should be addressed. These calls are for the reporting, on a firm-wide basis, of quantifiable data that is already required by the Environmental Protection Agency but is not typically available in detail in firms’ reports to investors.
235

Chitosan-Sericin Blend Membranes for Controlled Release of Drugs

Eslami, Shahabedin 22 December 2011 (has links)
The peak and valley problems caused by oral administration, injection or other conventional methods, call for developing systems that can deliver therapeutics more effectively. As one of the techniques, diffusion-controlled drug release membranes have significant interest due to great ease with which they can be designed to achieve near-zeroth-order release kinetics. Since diffusion is the rate-limiting step in these systems, determining the permeability and diffusivity of drug molecules in the membrane is therefore important in evaluating drug release performance. This study focuses on the Membrane Permeation Controlled Release (MPC) system, which involves a non-porous (dense) membrane, comprising of two biopolymers, sericin and chitosan. Ciprofloxacin hydrochloride and (+)-cis-diltiazem hydrochloride were used as hydrophilic model drugs, and nitro-2-furaldehyde semicarbazone (Nitrofurazon) was used as a hydrophobic model drug. Permeation experiments were carried out in a semi-infinite reservoir/receptor system to simulate in-vitro drug release. The intrinsic permeability and diffusivity (P, D) of the drugs through the membranes were determined using a modified time-lag method based on short time permeation and mass balance method based on long time permeation. The partition coefficients Kd of the drugs in the membranes and the swelling degree of the membranes were determined by sorption/desorption experiments. The diffusivities of the drugs were also determined from the sorption/desorption kinetics. Over the experimental ranges tested, the drug concentration and membrane cross-linking did not have significant effects on these parameters presumably due to the relatively low drug concentrations and mild crosslinkings of the membranes. The diffusivity coefficients of ciprofloxacin hydrochloride, (+)-cis-diltiazem hydrochloride and nitrofurazon in the membranes were found to be in the range of (2.0-2.6)×〖10〗^(-9)±2.6×〖10〗^(-10) cm2/s, (2.5-2.6) ×〖10〗^(-9)±1.1×〖10〗^(-10) and (38-134) ×〖10〗^(-9)±33.1×〖10〗^(-9) (cm2/s), respectively, and their permeability coefficients were in the range of (24-29)×〖10〗^(-8),(51-52) ×〖10〗^(-8) and (131-169) ×〖10〗^(-8) (cm2/s), respectively. The partition coefficients were determined to be around 0.91±0.21, 25±0.12 and 26±0.31, respectively. The diffusivity coefficients determined from sorption experiments for ciprofloxacin hydrochloride, diltiazem hydrochloride and nitrofurazon were found to be in the range of (3.2-7.6) ×〖10〗^(-9)±6.3×〖10〗^(-8), (6-10) ×〖10〗^(-9)±2.6×〖10〗^(-8) and (15-18) ×〖10〗^(-9)±2.7×〖10〗^(-7) (cm2/s), respectively. Also the diffusivity coefficients determined from sorption experiments for ciprofloxacin hydrochloride, diltiazem hydrochloride and nitrofurazon were in the range of (20-47) ×〖10〗^(-9), (12-24) ×〖10〗^(-9) and (11-20) ×〖10〗^(-9) (cm2/s), respectively. Nonetheless the differences in the diffusivities calculated from permeation and sorption/desorption experiments are considered to be acceptable, in view of the different experimental techniques used in this work, for the purpose of comparison of the membrane diffusivity and permeability.
236

Analysis and entrapment of select antioxidants from chokecherry and Saskatoon berry fruits

Konecsni, Kelly Alyson 03 June 2011 (has links)
The major objectives of this research were to produce a phenolic rich isolate from two locally grown Saskatchewan fruits, chokecherries and saskatoons, develop an encapsulation system for the phenolic isolate, and test this system for the delivery of the phenolic isolate in an animal (rat) model. Natural phenolic compounds present in plants such as fruits have antioxidant and free radical scavenging activities, which have been proposed to have health benefits. The extraction of these compounds from plants is commonly performed using methanol despite being toxic to both humans and animals. As such, ethanol was investigated for its ability to extract phenolics from plants as a food safe alternative to methanol. Phenolic extraction from chokecherries with ethanol:formic acid:water (EFW) resulted in higher concentrations (9.83 mg gallic acid equivalents (GAE)/g fresh weight) than with methanol:formic acid:water (MFW) (7.97 mg GAE/g fresh weight). Results from saskatoons showed similar phenolic levels of 4.26 and 4.21 mg GAE/g fresh weight with MFW and ethanol (EFW), respectively. These results showed that EFW was a suitable substitute for MFW in phenolic compound isolation from chokecherries and saskatoons, and could be used to produce extracts that were safe for use in foods and feeds. High performance liquid chromatography with photodiode array detection (HPLC-PDA) was used to determine the phenolic compound composition of the raw fruits and their phenolic rich isolates. Chlorogenic acid was identified in both chokecherry and saskatoon samples, and rutin was also shown to be present in saskatoons. These identifications were based on the relative retention time and ultra violet-visual spectra comparisons to standards. Solid phase extraction (SPE) using Amberlite XAD-16 was employed to produce phenolic isolates from chokecherries and saskatoons. HPLC-PDA results determined that there was a ~2.7x and ~1.6x increase in peak area for chokecherries and saskatoons, respectively when SPE was employed. The antioxidant activity of the extracts and isolates was determined using in vitro radical scavenging tests including 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2´-azinobis-3-ethylbenzthiazoline-sulphonic acid (ABTS). The EFW chokecherry extract and isolate had the highest overall free radical scavenging activity. Crude fruit extracts exhibited lower free radical scavenging values compared to the isolate samples in both of the assays performed. The fruit phenolic isolates were encapsulated in chitosan (CH) sodium tripolyphosphate (TPP) nanoparticles at a ratio of 4.0:1.0 (CH:TPP). HPLC-PDA was used to determine the entrapment efficiency of phenolic isolates to be 15.9 ± 2.7% and 23.0 ± 7.1% for chokecherries and saskatoons, respectively. Characteristics such as the size, surface potential and phenolic release were determined for the two fruit isolate containing nanoparticles. The size of the nanoparticles were 527.90 ± 74.57 nm and 443.03 ± 15.79 nm for chokecherries and saskatoons, respectively. Both of the nanoparticle systems had positive surface charges at 52.70 ± 2.93 mV and 54.43 ± 1.27 mV for chokecherries and saskatoons, respectively. The release properties of the CH:TPP nanoparticles containing fruit phenolics were examined in enzymatic simulated intestinal fluid and resulted in ~23% and ~28% release of chokecherry and saskatoon phenolics, respectively. Saskatoon phenolic isolates and isolates encapsulated in CH:TPP were gavage fed to rats (six animals in each of the two groups) at a dosage rate of 276.36 ± 9.74 mg/kg body weight. The saskatoon isolate contained 12.44 ± 0.44 mg/kg body weight anthocyanins (~3.30 mg anthocyanin per rat). These animals were sacrificed after 1 h and all stomach tissue samples in each of the treatment groups contained detectable levels of anthocyanins. In the small intestine tissues all six of the saskatoon isolate and three of the encapsulated isolate groups had detectable amounts of anthocyanins, while in the large intestine tissue, only one sample from the isolate group showed detectable amounts of anthocyanins. Although other tissues were tested (brain, heart, kidney and liver), anthocyanins were not detected. Therefore anthocyanins were detected in the gastrointestinal tract of both of the treatment groups. The research performed therefore illustrated that phenolic compounds can be extracted from fruit sources using EFW and can be successfully encapsulated in chitosan tripolyphosphate capsules allowing for targeted delivery in an animal model.
237

Att veta Gudarnas hemlighet : En sårbarhetsanalys av omständigheterna kring stormen Gudrun med pressure and release modellen / To know the secrets of the Gods : A vulnerability analysis of the circumstances regarding the storm Gudrun with the Pressure And Release Model

Fransson, Cecilia January 2012 (has links)
The concept of vulnerability is the capacity or the sensitivity to become damaged. Vulnerability are characterized by one or more of the following terms; a system´s sensitivity to exposure to shock, stress or interference, the state of the system in relations to a threshold of damages, and the system´s ability to adapt to the changing circumstances. Vulnerability in this study is referring to the sensitivity of the circumstances that lead to sustainable livelihood that can´t be maintain and that there is an inability to cope with and manage stress. The choice of making a study in this area is based on that action needs to be taken to moderate the vulnerable aspects of society, in this respect in relations to storms. Analyzes of the social vulnerability to climate change or natural events is needed for effective actions. The purpose of this study is to report on the vulnerability of the community- and household levels in relations with storms, in this case the storm Gudrun. The objective of this study is that it can be used as a basis for comparison with subsequent storms and also as a basis for preventive measures. The method used in this study is Pressure and Release Model (PAR) model ant it works like an explanatory model for the vulnerability involving the root causes of global, regional pressures and local vulnerable conditions. The results are that the root causes are forest policy, economic and political power and urbanization; the dynamic pressures are deficiencies in crisis management activities and population pressure in cities and the unsafe conditions are the countryside surrounded by forest, lack of resources and knowledge, and vulnerable electricity- and telephone networks.
238

Relation of silver release and antimicrobial effect in-vitro of silver containing wound dressings

Jakobsen, Carolin January 2010 (has links)
Silver was used for its antimicrobial effect by the ancient Greeks, long before the existence of microorganisms were first suspected. Nowadays a wide range of antimicrobial dressings containing silver, either incorporated within or applied on the dressings, are available for clinical use. This type of dressings is designed to provide the antimicrobial activity of silver in a more convenient application. The aim with this master thesis was to evaluate if silver release and antimicrobial effect of nine silver containing dressings are dependent on the test medium and if there is any relation between silver release and antimicrobial effect. Release of silver and antimicrobial effect was evaluated by using a 6-well co-culture system, with inoculated test medium in the wells and dressing pieces in the culture well inserts. Three different test media with increased complexity and nutrient value were inoculated with either Results show that release of silver depends on the test fluid used; for phosphate buffered saline (PBS), the silver concentration was as most 1.2 ppm, but for a complex media containing calf serum (SWF), it varied from 9 ppm to 134 ppm. The viable counts in PBS were reduced by at least 3 log units for all dressings and bacteria, whereas in SWF there were no reduction and instead growth was observed. In general, a high release resulted in less bacterial growth. Results also indicated that kinetics of silver release affect the antimicrobial effect. It is likely to assume that it is important for a dressing to release silver quickly. It has previously not been possible to correlate silver release of wound care dressings and antimicrobial effect, since the two factors have been measured in different test systems and in different media. Since both factors depend on test medium and method used, it is shown in the present study that it is important to use relevant test medium for in-vitro evaluation. When measuring silver release and antimicrobial effect in the same test system, a relation is found.
239

Effect of Pore Size and Thickness on Critical Pressure of Elastic Systems

Carter, Barton P. 19 July 2005 (has links)
Significant energy savings can be achieved by improving efficiency of water removal in the press section of a paper machine, rather than energy-intensive evaporative dryer cans. Impulse drying is a novel technology to remove water from the sheet in the press section by using a heated press roll. Delamination is a major challenge to be overcome before impulse drying can be implemented successfully. Delamination is caused by a region of high temperature liquid water under high pressure in the press. Upon exiting the nip, the pressure drops and the high temperature water flashes to steam. If the expansion of the steam is too strong, the bonds between the fibers will fail and a blister will form. The formation of this blister is characteristic of delamination. The goal of this project was to understand the internal mechanics of a wet web as it exits the nip of an impulse dryer. In this way, the components of the sheet can be tailored to open the operating window of impulse drying. A mathematical model, developed to describe the deflection and delamination of an elastic membrane, was utilized in this work. Three failure criteria were employed to represent delamination of this pliable membrane from the more rigid sub layers in the sheet. The experimental portion of this effort was devoted to showing the validity of these models and which was the best fit. A series of experiments were employed to validate the model. A peel test was used to determine the amount of work needed to pull a membrane from a rigid substrate. Pressurized blister experiments were conducted to find the relationship between critical pressure and initial defect size. The predictions from the mathematical model were then compared to these experimental values. Finally, work was done to understand the physics of the delamination of a porous membrane.
240

In situ chemical oxidation of TCE-contaminated groundwater using slow permanganate-releasing material

Wang, Sze-Kai 03 August 2011 (has links)
The purpose of this study was to use controlled release technology combining with in situ chemical oxidation (ISCO) and permeable reactive barrier (PRB) to remediate TCE-contaminated groundwater. In this study, potassium permanganate (KMnO4) releasing material was designed for potassium permanganate release in groundwater. The components of potassium permanganate releasing material included poly (£`-caprolactone) (PCL), potassium permanganate, and starch with a weight ratio of 2:1:0.5. Approximately 63.8% (w/w) of potassium permanganate was released from the material after 76 days of operation. The released was able to oxidize contaminant in groundwater. Results from the solid oxidation demand (SOD) experiment show that the consumption rate increased with increased contaminant concentration. TCE removal efficiency increased with the increased TCE concentration. The second-order rate law can be used to simulate the TCE degradation trend. In the column experiment, results show that the released MnO4- could oxidize TCE and TCE degradation byproducts when 95.6 pore volume (PV) of contaminated groundwater was treated. More than 95% of TCE removal can be observed in the column study. Although the concentration of manganese dioxide (MnO2) began to rise after 8.8 PV of operation, TCE removal was not affected. Results also show that low level of hexavalent chromium was detected (< 0.05 mg/L). Results from the scanning electron microscope (SEM) and energy-dispersive spectroscope (EDX) analyses show that the amounts of manganese and potassium in the materials decreased after the releasing experiment. Results indicate that the concentration of TCE and SOD need to be analyzed before the releasing materials are applied in situ. In the practical application, the releasing materials will not become solid wastes because they are decomposed after use. If this slow-releasing technology can be combined with a permeable reactive barrier system, this technology will become a more economic and environmentally-friendly green remedial system.

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