123 research outputs found
INFRARED ABSORPTION SPECTROSCOPY OF SMALL CARBON CLUSTER WATER COMPLEXES ISOLATED IN SOLID Ar
No full text B.J. Ortman, R.H. Hauge, J.L. Margrave, and Z.H. Kafafi, J. Phys. Chem. 94, 7973 (1990). J. Szczepanski, S. Ekem, and M. Vala, J. Phys. Chem. 99, 8002 (1995). S. Ekern, J. Szczepanski, and M. Vala, J. Phys. Chem. 100, 16109 (1996). S. Ekern and M. Vala, J. Phys. Chem. 101, 3601 (1997).Author Institution: Department of Chemistry and The Center for Chemical Physics, GainesvilleThe 1:1 complexes between carbon clusters and the molecule formed in Ar matrices at 12K have been investigated In addition, IR absorption bands found with higher energy than the stretching bands have been assigned to 1:2 complexes with the general structure , rather than . The proposed structure is supported by geometry optimization and harmonic frequencies calculated at level for the and systems. In particular, the -labeled experimental spectra for and complexes will be presented and compared to the calculated ones at the level. The and final photoproducts observed after UV matrix photolysis will be discussed within the context of possible photo-production of these species in interstellar $space.^{cd}
Complex diffractive structures for surface plasmon resonance sensors
No full textTitle: Complex diffractive structures for surface plasmon resonance sensors Author: Milan Vala Institute of Photonics and Electronics ASCR, v.v.i. Supervisor of the doctoral thesis: Prof. Jiří Homola, Ph.D., DSc. Institute of Photonics and Electronics, ASCR, v.v.i. Abstract: Nowadays, biosensors based on surface plasmon resonance (SPR) present one of the most advanced label-free optical biosensor technologies. These sensors are based on the monitoring of refractive index changes in the vicinity of a plasmonic metal and enable both rapid and sensitive detection of various biological or chemical agents as well as the analysis of biomolecular interactions in real time. This doctoral thesis presents the results of research of advanced diffractive structures having benefits for SPR biosensor technology. In addition to a theoretical analysis, this work consists of the fabrication and characterization of selected diffractive structures, and furthermore, the development of novel types of SPR biosensors based on these structures. In particular, the results presented in this thesis include the development of a novel method of fabrication of periodic plasmonic arrays based on multiple-beam interference lithography, the development of compact high-resolution diffraction grating-based SPR devices, and development of..
Komplexní difraktivní struktury pro senzory s povrchovými plazmony
No full textNázev práce: Komplexní difraktivní struktury pro senzory s povrchovými plazmony Autor: Milan Vala Ústav fotoniky a elektroniky AV ČR, v.v.i. Vedoucí doktorské práce: Prof. Ing. Jiří Homola, CSc., DSc. Ústav fotoniky a elektroniky AV ČR, v.v.i. Abstrakt: Biosenzory založené na rezonanci povrchových plazmonů (SPR) v současnosti představují jednu z nejpokročilejších bezznačkových technologií optické detekce. Tyto biosenzory jsou založeny na rozpoznávání změn indexu lomu v blízkosti plazmonicky aktivního kovu a umožňují rychlou a vysoce citlivou detekci celé řady biologických či chemických látek nebo analýzu biomolekulárních interakcí v reálném čase. Tato disertační práce představuje výsledky výzkumu vybraných typů komplexních difraktivních struktur s přínosem pro technologii SPR senzorů. Práce zahrnuje teoretickou analýzu, výrobu a charakterizaci vybraných difraktivních struktur a vývoj nových typů SPR biosenzorů. Výsledky práce zahrnují vývoj originální metody výroby periodických polí plasmonických nanočástic založené na vícesvazkové interferenční litografii, vývoj kompaktních SPR senzorů s vysokým rozlišením založených na difrakčních mřížkách a vývoj pokročilých SPR biosenzorů využívající speciální mody povrchového plazmonu s dlouhým a krátkým dosahem. Klíčová slova: difraktivní struktury, povrchový plazmon,...Title: Complex diffractive structures for surface plasmon resonance sensors Author: Milan Vala Institute of Photonics and Electronics ASCR, v.v.i. Supervisor of the doctoral thesis: Prof. Jiří Homola, Ph.D., DSc. Institute of Photonics and Electronics, ASCR, v.v.i. Abstract: Nowadays, biosensors based on surface plasmon resonance (SPR) present one of the most advanced label-free optical biosensor technologies. These sensors are based on the monitoring of refractive index changes in the vicinity of a plasmonic metal and enable both rapid and sensitive detection of various biological or chemical agents as well as the analysis of biomolecular interactions in real time. This doctoral thesis presents the results of research of advanced diffractive structures having benefits for SPR biosensor technology. In addition to a theoretical analysis, this work consists of the fabrication and characterization of selected diffractive structures, and furthermore, the development of novel types of SPR biosensors based on these structures. In particular, the results presented in this thesis include the development of a novel method of fabrication of periodic plasmonic arrays based on multiple-beam interference lithography, the development of compact high-resolution diffraction grating-based SPR devices, and development of...Faculty of Mathematics and PhysicsMatematicko-fyzikální fakult
Aplicação de revestimentos edíveis à base de subprodutos da indústria do pescado na preservação de atum fresco
No full textHoje em dia, a indústria do pescado enfrenta muitos desafios e oportunidades, uma vez que o peixe é um alimento extremamente perecível em comparação com outros produtos. Por outro lado, este setor gera uma elevada quantidade de subprodutos, das operações tradicionais de filetagem ou de corte em postas. O aproveitamento desses subprodutos assume assim uma importância muito grande, pois minimiza os problemas de produção e custo unitário das matérias-primas. A maior justificação, porém é de ordem nutricional, pois os subprodutos são uma fonte de nutrientes de baixo custo. Estes subprodutos ou partes subvalorizadas são ricos em proteínas de alto valor biológico e ricos em ácidos gordos polinsaturados da série ómega 3. Acrescenta ainda a presente conjetura económica, desfavorável às empresas do ramo alimentar portuguesas, principalmente às empresas de pescado (devido ao aumento progressivo no preço da matéria-prima) e, urge assim, valorizar os subprodutos e aumentar o tempo de vida útil do pescado fresco, no sentido de revitalizar o mercado.
A utilização de revestimentos comestíveis é um método promissor que permite proteger a qualidade dos produtos da pesca, aumentando o tempo de prateleira, sem comprometer a frescura.
O objetivo principal deste trabalho foi avaliar o efeito da aplicação de revestimentos à base de gelatina de pele de atum (Thunnus obesus) (5%) com incorporação de extrato de algas (Codium spp e Fucus vesiculosus) (1%) na qualidade físico-química e microbiológica de atum fresco, durante o armazenamento (12 dias a 4°C).
Foram desenvolvidas três soluções de revestimento à base de gelatina extraída de peles de atum (G), com ou sem incorporação de extratos de macroalgas (Codium spp (GC) e Fucus vesiculosus (GF)). O método de extração de gelatina a partir de peles de atum foi selecionado com base no rendimento do processo. Os revestimentos foram aplicados por aspersão aos lombos de atum fresco. Ao longo de 12 dias de armazenamento a 4 ± 1°C foram efetuadas várias análises físicas e químicas às postas de atum para poder avaliar o efeito dos revestimentos na manutenção da qualidade do produto.
O trabalho realizado demonstrou que a metodologia de extração utilizada permite obter um rendimento na ordem dos 29%.
Os revestimentos desenvolvidos juntamente com uma temperatura de armazenamento de 4 °C mostram ser a boa opção para manter os parâmetros de tempo de prateleira do atum durante 12 dias. O teor de azoto básico volátil e o número total de microrganismos apresentam valores inferiores aos limites máximos recomendados, a cor vermelha mantém-se durante mais dias e o valor de pH mantém-se inferior ao controlo para as amostras com revestimento ao fim dos 12 dias.
Em suma, a utilização de revestimentos à base de gelatina de peles de atum pode ser uma boa opção para prolongar o tempo de prateleira do atum refrigerado. Por outro lado, o aproveitamento dos subprodutos comestíveis das operações de transformação do atum assume uma importância muito grande, pois minimiza os problemas de produção e custo unitário das matérias-primas
Preface of the “Symposium on Dynamical Systems and their Applications to Advanced Materials, Structures and Technologies”
No full textELECTRONIC AND VIBRATIONAL ABSORPTION SPECTRA OF THE TETRACENE AND PENTACENE RADICAL CATIONS ISOLATED IN ARGON MATRICES
No full text J. Szczepanski and M. Vala, Astrophys. J. 414, 646 (1993).Author Institution: Department of Chemistry, University of FloridaThe low energy electron impact Technique has been employed to ionize tetracene and pentacene in an Ar or Ar/0.1% gas phase mixture. The electron bombardment products were deposited and stabilized in an argon matrix at 12K. An intensity correlation between the 392mm (tetracene) or 954mm (pentacene) electronic bands due to the radical cations and the newly observed vibrational bands was sought by varying the ratio of the abundance of tetracene or pentacene cations to all other species in the matrix. For these, and other polycyclic aromatic; hydrocarbons reported , the intensity distribution of the IR bands is significantly different from the intensity distribution of the neutral parents. The analysis of the vibrational energy shifts versus local charge density values for some normal modes for the series of linear polycyclic aromatic hydrocarbon cations from naphthalene to pentacene will be presented
Comparing consortial repositories: a model-driven analysis
No full textThis study aims to provide a comparative assessment of different repository consortia as a reference to inform future work in the area. A review of the literature was used to identify repository consortia, and their features were compared. Three models of consortial repositories were derived from this comparison, based on their structure and aims. The consortial models were based around either: creating a shared repository for the members, developing a repository software platform or creating a metadata harvesting service to aggregate content. Using case studies of each type of repository consortium, each model was assessed in terms of its particular strengths and weaknesses. These strengths were then compared across the models to enable those considering a consortial repository project to assess which model, or combination of models, would best address their needs and to aid in project planning
Computational prediction and control of energy consumption for heating in building structures
No full textComputational analysis of thermal transfer and related phenomena based on the Fourier method
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