277 resultados para Film preparation
Resumo:
In the past 20 years, mesoporous materials have been attracted great attention due to their significant feature of large surface area, ordered mesoporous structure, tunable pore size and volume, and well-defined surface property. They have many potential applications, such as catalysis, adsorption/separation, biomedicine, etc. [1]. Recently, the studies of the applications of mesoporous materials have been expanded into the field of biomaterials science. A new class of bioactive glass, referred to as mesoporous bioactive glass (MBG), was first developed in 2004. This material has a highly ordered mesopore channel structure with a pore size ranging from 5–20 nm [1]. Compared to non-mesopore bioactive glass (BG), MBG possesses a more optimal surface area, pore volume and improved in vitro apatite mineralization in simulated body fluids [1,2]. Vallet-Regí et al. has systematically investigated the in vitro apatite formation of different types of mesoporous materials, and they demonstrated that an apatite-like layer can be formed on the surfaces of Mobil Composition of Matters (MCM)-48, hexagonal mesoporous silica (SBA-15), phosphorous-doped MCM-41, bioglass-containing MCM-41 and ordered mesoporous MBG, allowing their use in biomedical engineering for tissue regeneration [2-4]. Chang et al. has found that MBG particles can be used for a bioactive drug-delivery system [5,6]. Our study has shown that MBG powders, when incorporated into a poly (lactide-co-glycolide) (PLGA) film, significantly enhance the apatite-mineralization ability and cell response of PLGA films. compared to BG [7]. These studies suggest that MBG is a very promising bioactive material with respect to bone regeneration. It is known that for bone defect repair, tissue engineering represents an optional method by creating three-dimensional (3D) porous scaffolds which will have more advantages than powders or granules as 3D scaffolds will provide an interconnected macroporous network to allow cell migration, nutrient delivery, bone ingrowth, and eventually vascularization [8]. For this reason, we try to apply MBG for bone tissue engineering by developing MBG scaffolds. However, one of the main disadvantages of MBG scaffolds is their low mechanical strength and high brittleness; the other issue is that they have very quick degradation, which leads to an unstable surface for bone cell growth limiting their applications. Silk fibroin, as a new family of native biomaterials, has been widely studied for bone and cartilage repair applications in the form of pure silk or its composite scaffolds [9-14]. Compared to traditional synthetic polymer materials, such as PLGA and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), the chief advantage of silk fibroin is its water-soluble nature, which eliminates the need for organic solvents, that tend to be highly cytotoxic in the process of scaffold preparation [15]. Other advantages of silk scaffolds are their excellent mechanical properties, controllable biodegradability and cytocompatibility [15-17]. However, for the purposes of bone tissue engineering, the osteoconductivity of pure silk scaffolds is suboptimal. It is expected that combining MBG with silk to produce MBG/silk composite scaffolds would greatly improve their physiochemical and osteogenic properties for bone tissue engineering application. Therefore, in this chapter, we will introduce the research development of MBG/silk scaffolds for bone tissue engineering.
Resumo:
The self-assembling behavior and microscopic structure of zinc oxide nanoparticle Langmuir-Blodgett monolayer films were investigated for the case of zinc oxide nanoparticles coated with a hydrophobic layer of dodecanethiol. Evolution of nanoparticle film structure as a function of surface pressure (π) at the air-water interface was monitored in situ using Brewster’s angle microscopy, where it was determined that π=16 mN/m produced near-defect-free monolayer films. Transmission electron micrographs of drop-cast and Langmuir-Schaefer deposited films of the dodecanethiol-coated zinc oxide nanoparticles revealed that the nanoparticle preparation method yielded a microscopic structure that consisted of one-dimensional rodlike assemblies of nanoparticles with typical dimensions of 25 x 400 nm, encased in the organic dodecanethiol layer. These nanoparticle-containing rodlike micelles were aligned into ordered arrangements of parallel rods using the Langmuir-Blodgett technique.
Resumo:
It is predicted that with increased life expectancy in the developed world, there will be a greater demand for synthetic materials to repair or regenerate lost, injured or diseased bone (Hench & Thompson 2010). There are still few synthetic materials having true bone inductivity, which limits their application for bone regeneration, especially in large-size bone defects. To solve this problem, growth factors, such as bone morphogenetic proteins (BMPs), have been incorporated into synthetic materials in order to stimulate de novo bone formation in the center of large-size bone defects. The greatest obstacle with this approach is that the rapid diffusion of the protein from the carrier material, leading to a precipitous loss of bioactivity; the result is often insufficient local induction or failure of bone regeneration (Wei et al. 2007). It is critical that the protein is loaded in the carrier material in conditions which maintains its bioactivity (van de Manakker et al. 2009). For this reason, the efficient loading and controlled release of a protein from a synthetic material has remained a significant challenge. The use of microspheres as protein/drug carriers has received considerable attention in recent years (Lee et al. 2010; Pareta & Edirisinghe 2006; Wu & Zreiqat 2010). Compared to macroporous block scaffolds, the chief advantage of microspheres is their superior protein-delivery properties and ability to fill bone defects with irregular and complex shapes and sizes. Upon implantation, the microspheres are easily conformed to the irregular implant site, and the interstices between the particles provide space for both tissue and vascular ingrowth, which are important for effective and functional bone regeneration (Hsu et al. 1999). Alginates are natural polysaccharides and their production does not have the implicit risk of contamination with allo or xeno-proteins or viruses (Xie et al. 2010). Because alginate is generally cytocompatible, it has been used extensively in medicine, including cell therapy and tissue engineering applications (Tampieri et al. 2005; Xie et al. 2010; Xu et al. 2007). Calcium cross-linked alginate hydrogel is considered a promising material as a delivery matrix for drugs and proteins, since its gel microspheres form readily in aqueous solutions at room temperature, eliminating the need for harsh organic solvents, thereby maintaining the bioactivity of proteins in the process of loading into the microspheres (Jay & Saltzman 2009; Kikuchi et al. 1999). In addition, calcium cross-linked alginate hydrogel is degradable under physiological conditions (Kibat PG et al. 1990; Park K et al. 1993), which makes alginate stand out as an attractive candidate material for the protein carrier and bone regeneration (Hosoya et al. 2004; Matsuno et al. 2008; Turco et al. 2009). However, the major disadvantages of alginate microspheres is their low loading efficiency and also rapid release of proteins due to the mesh-like networks of the gel (Halder et al. 2005). Previous studies have shown that a core-shell structure in drug/protein carriers can overcome the issues of limited loading efficiencies and rapid release of drug or protein (Chang et al. 2010; Molvinger et al. 2004; Soppimath et al. 2007). We therefore hypothesized that introducing a core-shell structure into the alginate microspheres could solve the shortcomings of the pure alginate. Calcium silicate (CS) has been tested as a biodegradable biomaterial for bone tissue regeneration. CS is capable of inducing bone-like apatite formation in simulated body fluid (SBF) and its apatite-formation rate in SBF is faster than that of Bioglass® and A-W glass-ceramics (De Aza et al. 2000; Siriphannon et al. 2002). Titanium alloys plasma-spray coated with CS have excellent in vivo bioactivity (Xue et al. 2005) and porous CS scaffolds have enhanced in vivo bone formation ability compared to porous β-tricalcium phosphate ceramics (Xu et al. 2008). In light of the many advantages of this material, we decided to prepare CS/alginate composite microspheres by combining a CS shell with an alginate core to improve their protein delivery and mineralization for potential protein delivery and bone repair applications
Resumo:
The tear film plays an important role preserving the health of the ocular surface and maintaining the optimal refractive power of the cornea. Moreover dry eye syndrome is one of the most commonly reported eye health problems. This syndrome is caused by abnormalities in the properties of the tear film. Current clinical tools to assess the tear film properties have shown certain limitations. The traditional invasive methods for the assessment of tear film quality, which are used by most clinicians, have been criticized for the lack of reliability and/or repeatability. A range of non-invasive methods of tear assessment have been investigated, but also present limitations. Hence no “gold standard” test is currently available to assess the tear film integrity. Therefore, improving techniques for the assessment of the tear film quality is of clinical significance and the main motivation for the work described in this thesis. In this study the tear film surface quality (TFSQ) changes were investigated by means of high-speed videokeratoscopy (HSV). In this technique, a set of concentric rings formed in an illuminated cone or a bowl is projected on the anterior cornea and their reflection from the ocular surface imaged on a charge-coupled device (CCD). The reflection of the light is produced in the outer most layer of the cornea, the tear film. Hence, when the tear film is smooth the reflected image presents a well structure pattern. In contrast, when the tear film surface presents irregularities, the pattern also becomes irregular due to the light scatter and deviation of the reflected light. The videokeratoscope provides an estimate of the corneal topography associated with each Placido disk image. Topographical estimates, which have been used in the past to quantify tear film changes, may not always be suitable for the evaluation of all the dynamic phases of the tear film. However the Placido disk image itself, which contains the reflected pattern, may be more appropriate to assess the tear film dynamics. A set of novel routines have been purposely developed to quantify the changes of the reflected pattern and to extract a time series estimate of the TFSQ from the video recording. The routine extracts from each frame of the video recording a maximized area of analysis. In this area a metric of the TFSQ is calculated. Initially two metrics based on the Gabor filter and Gaussian gradient-based techniques, were used to quantify the consistency of the pattern’s local orientation as a metric of TFSQ. These metrics have helped to demonstrate the applicability of HSV to assess the tear film, and the influence of contact lens wear on TFSQ. The results suggest that the dynamic-area analysis method of HSV was able to distinguish and quantify the subtle, but systematic degradation of tear film surface quality in the inter-blink interval in contact lens wear. It was also able to clearly show a difference between bare eye and contact lens wearing conditions. Thus, the HSV method appears to be a useful technique for quantitatively investigating the effects of contact lens wear on the TFSQ. Subsequently a larger clinical study was conducted to perform a comparison between HSV and two other non-invasive techniques, lateral shearing interferometry (LSI) and dynamic wavefront sensing (DWS). Of these non-invasive techniques, the HSV appeared to be the most precise method for measuring TFSQ, by virtue of its lower coefficient of variation. While the LSI appears to be the most sensitive method for analyzing the tear build-up time (TBUT). The capability of each of the non-invasive methods to discriminate dry eye from normal subjects was also investigated. The receiver operating characteristic (ROC) curves were calculated to assess the ability of each method to predict dry eye syndrome. The LSI technique gave the best results under both natural blinking conditions and in suppressed blinking conditions, which was closely followed by HSV. The DWS did not perform as well as LSI or HSV. The main limitation of the HSV technique, which was identified during the former clinical study, was the lack of the sensitivity to quantify the build-up/formation phase of the tear film cycle. For that reason an extra metric based on image transformation and block processing was proposed. In this metric, the area of analysis was transformed from Cartesian to Polar coordinates, converting the concentric circles pattern into a quasi-straight lines image in which a block statistics value was extracted. This metric has shown better sensitivity under low pattern disturbance as well as has improved the performance of the ROC curves. Additionally a theoretical study, based on ray-tracing techniques and topographical models of the tear film, was proposed to fully comprehend the HSV measurement and the instrument’s potential limitations. Of special interested was the assessment of the instrument’s sensitivity under subtle topographic changes. The theoretical simulations have helped to provide some understanding on the tear film dynamics, for instance the model extracted for the build-up phase has helped to provide some insight into the dynamics during this initial phase. Finally some aspects of the mathematical modeling of TFSQ time series have been reported in this thesis. Over the years, different functions have been used to model the time series as well as to extract the key clinical parameters (i.e., timing). Unfortunately those techniques to model the tear film time series do not simultaneously consider the underlying physiological mechanism and the parameter extraction methods. A set of guidelines are proposed to meet both criteria. Special attention was given to a commonly used fit, the polynomial function, and considerations to select the appropriate model order to ensure the true derivative of the signal is accurately represented. The work described in this thesis has shown the potential of using high-speed videokeratoscopy to assess tear film surface quality. A set of novel image and signal processing techniques have been proposed to quantify different aspects of the tear film assessment, analysis and modeling. The dynamic-area HSV has shown good performance in a broad range of conditions (i.e., contact lens, normal and dry eye subjects). As a result, this technique could be a useful clinical tool to assess tear film surface quality in the future.
Resumo:
Bringing together the voices of leading and emerging scholars, this book provides critical approaches for reading children's literature and film. It argues for the significance of theory for reading texts written and produced for young people and integrates a wide range of critical perspectives, including schema theory, theories of space and place, cultural globalization, feminism, ecocriticism, adaptation theory, postcolonialism, and posthumanism.
Resumo:
This study uses dosimetry film measurements and Monte Carlo simulations to investigate the accuracy of type-a (pencil-beam) dose calculations for predicting the radiation doses delivered during stereotactic radiotherapy treatments of the brain. It is shown that when evaluating doses in a water phantom, the type-a algorithm provides dose predictions which are accurate to within clinically relevant criteria, gamma(3%,3mm), but these predictions are nonetheless subtly different from the results of evaluating doses from the same fields using radiochromic film and Monte Carlo simulations. An analysis of a clinical meningioma treatment suggests that when predicting stereotactic radiotherapy doses to the brain, the inaccuracies of the type-a algorithm can be exacerbated by inadequate evaluation of the effects of nearby bone or air, resulting in dose differences of up to 10% for individual fields. The results of this study indicate the possible advantage of using Monte Carlo calculations, as well as measurements with high-spatial resolution media, to verify type-a predictions of dose delivered in cranial treatments.
Resumo:
International Film Festivals play a vital role in shaping filmmakers’ careers. This paper presents some initial findings from a current major research project, highlighting the significance of particular festival programming of emerging female directors from developing nations. Some filmmakers showcased at festivals actively privilege the voices of women in their films as a means of commenting on pressing cultural and political issues. Ironically, other filmmakers do not subscribe to the label of “feminist” or “woman filmmaker”, even if their respective films represent a strongly coded woman’s point of view. Tensions also arise inevitably when scrutinising women filmmakers from developing nations within a first world film festival context. The expectations of the researcher, the festival, film critics and audiences inevitably must negotiate with the original intentions of the filmmaker. This paper explores the significance of women filmmakers in attendance at the Brisbane International Film Festival (2009) and the International Film Festival Rotterdam (2010).
Resumo:
This article compares YouTube and the National Film and Sound Archive (NFSA) as resources for television historians interested in viewing old Australian television programs. The author searched for seventeen important television programs, identified in a previous research project, to compare what was available in the two archives and how easy it was to find. The analysis focused on differences in curatorial practices of accessioning and cataloguing. NFSA is stronger in current affairs and older programs, while YouTube is stronger in game shows and lifestyle programs. YouTube is stronger than the NFSA on “human interest” material—births, marriages, and deaths. YouTube accessioning more strongly accords with popular histories of Australian television. Both NFSA and YouTube offer complete episodes of programs, while YouTube also offers many short clips of “moments.” YouTube has more surprising pieces of rare ephemera. YouTube cataloguing is more reliable than that of the NFSA, with fewer broken links. The YouTube metadata can be searched more intuitively. The NFSA generally provides more useful reference information about production and broadcast dates.
Resumo:
Chinese independent cinema has developed for more than twenty years. Two sorts of independent cinema exist in China. One is underground cinema, which is produced without official approvals and cannot be circulated in China, and the other are the films which are legally produced by small private film companies and circulated in the domestic film market. This sort of ‘within-system’ independent cinema has played a significant role in the development of Chinese cinema in terms of culture, economics and ideology. In contrast to the amount of comment on underground filmmaking in China, the significance of ‘within-system’ independent cinema has been underestimated by most scholars. This thesis is a study of how political management has determined the development of Chinese independent cinema and how Chinese independent cinema has developed during its various historical trajectories. This study takes media economics as the research approach, and its major methods utilise archive analysis and interviews. The thesis begins with a general review of the definition and business of American independent cinema. Then, after a literature review of Chinese independent cinema, it identifies significant gaps in previous studies and reviews issues of traditional definition and suggests a new definition. After several case studies on the changes in the most famous Chinese directors’ careers, the thesis shows that state studios and private film companies are two essential domestic backers for filmmaking in China. After that, the body of the thesis provides an examination of the development of ‘within-system’ independent cinema. Specifically, three factors: government intervention, the majors’ performance (state studios and, later, the conglomerates) and the market conduct of independent cinema at various points in their trajectories are studied. The key findings of the study are as follows: First, most scholars have overlooked the existence and the significance of within-system Chinese independent cinema. Drawing on an American definition of the independent sector, this thesis proposes a definition of the sector in China: namely, any film that has not been financed, produced, and/or distributed by majors. The thesis also notes important contradictions in applying this definition: i.e. film-making is still dependent on policies that frame industry development. The thesis recognises that major tensions apply to filmmaking in China, which significantly differentiates the Chinese independents from those in the US. Second, the development of Chinese independent cinema is the result the rise of the private sector and the decline of the state studio system. As state studios encountered difficulties the private sector moved forward; consequently the environment improved for independent cinema. Third, before 2003, the film industry in China had little commercialisation. The government controlled independent cinema by means of license and censorship. State studios produced main melody films and Hollywood attracted most of the audiences. Many independent filmmakers focused on commercial films, thus contributing to film commercialisation. Fourth, after 2003, the film industry became increasingly fragmented. The government created distribution and exhibition opportunities for main melody films; conglomerates collaborated with Hong Kong players; Hong Kong co-productions and Hollywood occupied the film market; and small private film companies produced main melody films in order to earn meagre profits. The original contribution of the thesis is to advance the study of Chinese independent cinema. The study suggests a reasonable and practical definition of Chinese independent cinema. It shows how the Chinese government authorities have implemented economic measures to gain ideological control in the film industry. Finally, this the first study on Chinese independent cinema applying a synthesis of economic, political and historical perspectives.
Resumo:
We both love and hate our journalists. They are perceived as sexy and glamorous on the one hand, despicable and sleazy on the other. Opinion polls regularly indicate that we experience a kind of cultural schizophrenia in our relationship to journalists and the news media: sometimes they are viewed as heroes, at other times villains. From Watergate to the fabrication scandals of the 2000s, journalists have risen and fallen in public esteem. In this book, leading journalism studies scholar Brian McNair explores how journalists have been represented through the prism of one of our key cultural forms, cinema. Drawing on the history of cinema since the 1930s, and with a focus on the period 1997-2008, McNair explores how journalists have been portrayed in film, and what these images tell us about the role of the journalist in liberal democratic societies. Separate chapters are devoted to the subject of female journalists in film, foreign correspondents, investigative reporters and other categories of news maker who have featured regularly in cinema. The book also discusses the representation of public relations professionals in film. Illustrated throughout and written in an accessible and lively style suitable for academic and lay readers alike, Journalists in Film will be essential reading for students and teachers of journalism, and for all those concerned about the role of the journalist in contemporary society, not least journalists themselves. An appendix contains mini-essays on every film about journalism released in the cinema between 1997 and 2008.
Resumo:
For almost a decade before Hollywood existed, French firm Pathe towered over the early film industry with estimates of its share of all films sold around the world varying between 50-70%. Pathe was the first global entertainment company. This paper analyses its rise to market leadership by applying a theoretical framework drawn from the business literature on causes of industry dominance, which provides insights into how firms acquire and maintain market dominance, and in this case the film industry. This paper uses evidence presented by film historians to argue that Pathe “fits” the expected theoretical model of a dominant firm because it had a marketing orientation, used an effective quality-based competitive strategy and possessed the six critical strategic marketing capabilities that business research shows enable the best performing firms to consistently outperform rivals
Resumo:
In November 2010, the world watched as 33 Chilean miners were rescued from the depths of the earth where they had been stranded since July. We were able to watch because the world’s news media were there, drawn by the human drama, the suspense, the spectacle. It was a great news story, ideally suited for the 24-hour news culture we live in today, and the globalised audience that consumes it. Nothing much happened for 68 of those 69 days, until that final 24 hours when the miners emerged. But we were transfixed, engrossed, immersed in the story.