322 resultados para poly (lactide-co-glycolide)


Relevância:

20.00% 20.00%

Publicador:

Resumo:

A number of series of poly(acrylic acids) (PAA) of differing end-groups and molecular weights prepared using atom transfer radical polymerization were used as inhibitors for the crystallization of calcium oxalate at 23 and 80°C. As measured by turbidimetry and conductivity and as expected from previous reports, all PAA series were most effective for inhibition of crystallization at molecular weights of 1500–4000. However, the extent of inhibition was in general strongly dependent on the hydrophobicity and molecular weight of the end-group. These results may be explicable in terms of adsorption/desorption of PAA to growth sites on crystallites. The overall effectiveness of the series didn't follow a simple trend with end-group hydrophobicity, suggesting self-assembly behavior or a balance between adsorption and desorption rates to crystallite surfaces may be critical in the mechanism of inhibition of calcium oxalate crystallization.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A number of series of poly(acrylic acids) (PAA) of differing end-groups and molecular mass were used to study the inhibition of calcium oxalate crystallization. The effects of the end-group on crystal speciation and morphology were significant and dramatic, with hexyl-isobutyrate end groups giving preferential formation of calcium oxalate dihydrate (COD) rather than the more stable calcium oxalate monohydrate (COM), while both more hydrophobic end-groups and less-hydrophobic end groups led predominantly to formation of the least thermodynamically stable form of calcium oxalate, calcium oxalate trihydrate. Conversely, molecular mass had little impact on calcium oxalate speciation or crystal morphology. It is probable that the observed effects are related to the rate of desorption of the PAA moiety from the crystal (lite) surfaces and that the results point to a major role for end-group as well as molecular mass in controlling desorption rate.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Reviewing the breadth of current knowledge on schizophrenia, this handbook provides clear, practical guidelines for effective assessment and treatment in diverse contexts. Leading authorities have contributed 61 concise chapters on all aspects of the disorder and its clinical management. In lieu of exhaustive literature reviews, each chapter summarizes the current state of the science; highlights key points the busy practitioner needs to know; and lists recommended resources, including seminal research studies, invaluable clinical tools, and more. Comprehensive, authoritative, and timely, the volume will enable professionals in any setting to better understand and help their patients or clients with severe mental illness.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Background Delivering effective multiple health behavior interventions to large numbers of adults with chronic conditions via primary care settings is a public health priority. Purpose Within a 12-month, telephone-delivered diet and physical activity intervention with multiple behavioral outcomes, we examined the extent and co-variation of multiple health behavior change. Methods A cluster-randomized trial with 434 patients with type 2 diabetes or hypertension were recruited from 10 general practices, which were randomized to receive telephone counseling or usual care. Results Those receiving telephone counseling were significantly more likely than those in usual care to make greater reductions in multiple behaviors after adjusting for baseline risk behaviors (OR 2.42; 95%CI 1.43, 4.11). Controlling for baseline risk and group allocation, making changes to either physical activity, fat, vegetable, or fiber intake was associated with making significantly more improvements in other behaviors. Conclusions For patients with chronic conditions, telephone counseling can significantly improve multiple health behaviors, with behavioral changes tending to co-vary.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Photo-curable biodegradable macromers were prepared by ring opening polymerization of D,L-lactide (DLLA), (similar to)-caprolactone (CL) and 1,3-trimethylene carbonate (TMC) in the presence of glycerol or sorbitol as initiator and stannous octoate as catalyst, and subsequent methacrylation of the terminal hydroxyl groups. These methacrylated macromers, ranging in molecular weight from approximately 700 to 6000 g/mol, were cross-linked using ultraviolet (UV) light to form biodegradable networks. Homogeneous networks with high gel contents were prepared. One of the resins based on PTMC was used to prepare three-dimensional structures by stereo-lithography using a commercially available apparatus.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Photo-curable biodegradable macromers were prepared by ring opening polymerization of D,L-lactide (DLLA), ε-caprolactone (CL) and 1,3-trimethylene carbonate (TMC) in the presence of glycerol or sorbitol as initiator and stannous octoate as catalyst, and subsequent methacrylation of the terminal hydroxyl groups. These methacrylated macromers, ranging in molecular weight from approximately 700 to 6000 g/mol, were cross-linked using ultraviolet (UV) light to form biodegradable networks. Homogeneous networks with high gel contents were prepared. One of the resins based on PTMC was used to prepare three-dimensional structures by stereo-lithography using a commercially available apparatus.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper presents research in response to environmental concerns we face today. In a search for a better method to manage spaces and building resources consumed excessively through traditional top-down architectural solutions, the research began by speculating that the building spaces and resources can be managed by designing architectural systems that encourage a bottom-up approach. In other words, this research investigates how to design systems that encourage occupants and users of buildings to actively understand, manage and customise their own spaces. Specific attention is paid to the participation of building users because no matter how sophisticated the system is, the building will become as wasteful as conventional buildings if users cannot, or do not want to, utilise the system effectively. The research is still in its early stages. The intension of this paper is to provide a background to the issue, discuss researches and projects relevant to, but not necessarily about, architecture, and introduce a number of hypothesis and investigations to realise adaptable, participatory and sustainable environments for users.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Rapid prototyping techniques such as stereolithography allow for building designed tissue engineering scaffolds with high accuracy. In this work, a stereolithography resin based on poly(D,L-lactide) was developed. Biodegradable scaffolds with varying porosity were built from this resin. The scaffolds were analysed by μCT-scanning and compression testing. The porous structures showed excellent mechanical properties in the range of trabecular bone.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Co-creation between customers and providers has recently gained more attention by business service providers as a promising endeavour. The different perspectives of co-creation - innovation, sourcing and marketing - are well deployed. From a provider’s point of view, the question of how to manage business services with respect to co-creation is vitally important. However, service engineering and service lifecycle management typically take a mostly internal, closed-loop approach, although a logical implication of acknowledging the value co-creation perspective on “service” would be to leverage customer and other stakeholder competences to the full extent. This paper aims at reconciling the perspectives of co-creation and makes a contribution by analysing where and how co-creation can be effectively utilised throughout the various stages of a generic business service lifecycle. The result will be a framework guiding companies in using co-creation when managing their business services.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper investigates the research question ‘What is the effect of co-ethnic and non coethnic networking on business performance in Chinese immigrant businesses?’ The research will discuss key themes such as the extent to which Chinese immigrant entrepreneurs are embedded in co-ethnic and non co-ethnic networks and the affect of embeddedness on business performance, such as the entrepreneur’s satisfaction and business growth. Research on immigrant entrepreneurship has emerged as an important new area of inquiry within the field of entrepreneurship. The increased importance of the subject is due in part to major immigrant receiving countries, such as Australia, the United States and Canada, experiencing a high growth rate in their immigrant population. Reflecting on the existing research on immigrant entrepreneurship, it was decided to investigate the role of embeddedness on entrepreneurial business performance. This research seeks to identify the impact of embeddedness in co-ethnic and non co-ethnic networks on business performance of Chinese immigrant entrepreneurs in Australia. Chinese immigrant restaurant entrepreneurs in southeast Queensland, Australia were studied. The result expands on existing research on immigrant entrepreneurship, since the majority of immigrant entrepreneurship studies have been conducted on the United States and Canada immigrant experiences, but few have been conducted in the Australian immigrant entrepreneur context. This thesis also adds empirical testing to a research area with little empirical testing. The results indicated that embeddedness in the co-ethnic network is positively related to business performance measured by both growth and satisfaction. Embeddedness in the non co-ethnic network of the Chinese immigrant entrepreneurs in Australia did not show a similar pattern in accordance with studies conducted in the United States and Canada. This result is interesting and creates the opportunity for future research employing a comparative study.