RESUMO
This paper brings an overview of photoisomerization-derived properties in azobenzene-containing nanostructured films produced with the Langmuir-Blodgett (LB) and layer-by-layer (LbL) methods. Emphasis was placed on the optical storage and formation of surface-relief gratings (SRGs), where the distinctive properties of the nanostructured films were highlighted. For optical storage, in particular, a discussion was made of the higher birefringence induced in LB films from azopolymers due to their organized nature, and of the strong effects from ionic interactions on the photoisomerization of azochromophores in LbL films. The molecular-level control of film properties in the LbL films is described as being responsible for the varied behavior observed in the photoinscription of SRGs, which may involve considerable level of photodegradation depending on the film fabrication conditions and materials used.
Assuntos
Compostos Azo/química , Membranas Artificiais , Nanoestruturas/química , Dispositivos de Armazenamento Óptico , Compostos Azo/síntese química , Compostos Azo/efeitos da radiação , Estrutura Molecular , Propriedades de SuperfícieRESUMO
The buildup of layer-by-layer (LBL) films from chitosan and the azodye Ponceau-S (PS) was investigated under various experimental conditions, and the resulting films were used in optical storage experiments. The kinetics for the writing process in optical storage was faster for LBL films prepared at low pHs, probably because the films had a larger free volume for isomerization of the chromophores. The nanostructured nature of the LBL films also affected the crystallinity of chitosan, which was considerably decreased in this type of film as chitosan became protonated because of the electrostatic interactions between adjacent layers.
Assuntos
Quitina/análogos & derivados , Dispositivos de Armazenamento Óptico , Compostos Azo , Quitosana , CorantesRESUMO
Layer-by-layer (LBL) films of chitosan alternated with an azopolymer, PS119, have been used for optical storage and fabrication of surface-relief gratings. The optical properties stem from the trans-cis-trans isomerization cycles undergone by the azochromophore, with a kinetics for writing the birefringence pattern that is much slower than in the spin-coated or cast films of azopolymers. The long writing times, of the order of 100 s, are due to the electrostatic interactions between adjacent chitosan and PS119 layers. Such interactions are also responsible for other features in the LBL films, namely the increase in the amount of adsorbed material when the pH of the preparation solution is decreased and the large residual birefringence after the writing laser is switched off. Gratings could be inscribed with s-polarized but not with p-polarized light, indicating a mass transport process associated with photodegradation.
Assuntos
Quitina/análogos & derivados , Dispositivos de Armazenamento Óptico , Compostos Azo , Birrefringência , Quitosana , Polímeros , Propriedades de SuperfícieRESUMO
Las tecnologías de almacenamiento de información más utilizadas actualmente son la óptica y la magnética. Entre los dispositivos magnéticos se hallan los populares discos flexibles y duros, así como los menos conocidos zip, superdisk, syquest, jaz, y otros. Los CD y los DVD simbolizan los soportes ópticos. Ellos, aunque con frecuencia se consideran la respuesta más adecuada para la conservación a largo plazo de la información, requieren de cuidados especiales para su conservación en el tiempo. Se exponen las características principales de estos soportes, sus materiales, así como los daños que experimentan debido a la acción, tanto de factores internos como externos. Se realizan una serie de recomendaciones útiles para su conservación a largo plazo(AU)
Assuntos
Armazenamento e Recuperação da Informação , Dispositivos de Armazenamento Óptico , Discos Compactos , CD-ROM , Gravação em FitaRESUMO
Las tecnologías de almacenamiento de información más utilizadas actualmente son la óptica y la magnética. Entre los dispositivos magnéticos se hallan los populares discos flexibles y duros, así como los menos conocidos zip, superdisk, syquest, jaz, y otros. Los CD y los DVD simbolizan los soportes ópticos. Ellos, aunque con frecuencia se consideran la respuesta más adecuada para la conservación a largo plazo de la información, requieren de cuidados especiales para su conservación en el tiempo. Se exponen las características principales de estos soportes, sus materiales, así como los daños que experimentan debido a la acción, tanto de factores internos como externos. Se realizan una serie de recomendaciones útiles para su conservación a largo plazo
Assuntos
CD-ROM , Discos Compactos , Armazenamento e Recuperação da Informação , Dispositivos de Armazenamento Óptico , Gravação em FitaRESUMO
Reseña que muestra información acerca del tipo, forma, uso y mantenimiento de los microscopios ópticos, a través de los siguientes puntos: 1. Introducción 2. Objetivos didácticos 3. Antecedentes históricos 4. Optica básica 5. Prismas 6. Aberraciones y distorsiones en las imágenes 7. Otros fenómenos ópticos 8. Las lupas y otros tipos de lentes simples 9. Optica de los microscopios compuestos 10. Imágenes que se forman en los microscopios 11. Sistema de iluminación 12. Objetivos y oculares 13. Otros tipos de microscopios 14. Sistema mecánico 15. Mantenimiento preventivo y correctivo de los microscopios 16. Glosario de términos
Assuntos
Manutenção de Equipamento , Manual de Referência , México , Microscopia Eletrônica , Dispositivos de Armazenamento ÓpticoAssuntos
Serviço Hospitalar de Emergência , Sistemas Computadorizados de Registros Médicos/economia , Dispositivos de Armazenamento Óptico/economia , Catolicismo , Colorado , Análise Custo-Benefício , Hospitais com 100 a 299 Leitos , Hospitais Religiosos , Sistemas Computadorizados de Registros Médicos/organização & administração , Técnicas de Planejamento , Análise e Desempenho de Tarefas , Gestão da Qualidade TotalRESUMO
Optical imaging systems can help lead the way to the computer-based patient record. This article addresses several security clearance issues that these systems raise and tells how one facility responded to them.
Assuntos
Serviço Hospitalar de Registros Médicos/organização & administração , Sistemas Computadorizados de Registros Médicos , Dispositivos de Armazenamento Óptico , Segurança Computacional , Hospitais com mais de 500 Leitos , Auditoria Médica , Projetos de PesquisaRESUMO
The literature concerning the diffusion of innovations reveals that it is not surprising that a promising technology is confronting obstacles in its development and implementation. Alternative technologies also often appear that address the same or similar problems. Better information enables physicians to provide medical care that is less expensive and less error prone. The prescription of medications is reduced in number and cost when the prescribing physician knows the current and previous medications of the patient. The ordering of clinical tests is reduced in number and cost, and the ordering of timely retesting is more likely when physicians have before them information about previous testing of their patient. The challenge is in how the portability of the patient card and its ability to be self-contained can enhance medical practice.