Search results for "Visible"

Plasma Polymer Membranes for Immobilising Metalloporphyrins

2013

Atmospheric pressure dielectric barrier discharge formation of organosilicon thin films loaded with zinc 5,10,15,20-tetraphenylporphyrin (Zn(TPP)) was investigated for different deposition conditions. UV–visible spectroscopy and scanning electron microscopy revealed the effects of the metalloporpyhrins injection parameters and the plasma polymerisation conditions can affect the dispersion of the metalloporphyrins and the morphology of the coatings. The stability of the embedded Zn(TPP) molecules was investigated by orbitrap mass spectrometry.

α-Chymotrypsin-Catalyzed Reaction Confined in Block-Copolymer Vesicles

2010

Herein the reactivity of the enzyme α-chymotrypsin in the confinement of polystyrene-block-poly(acrylic acid) (PS-b-PAA) vesicles was investigated. Enzyme and substrate molecules were encapsulated in PS-b-PAA vesicles with internal diameters ranging from 26 nm to 165 nm during the formation of the vesicles. While the loading efficiencies of enzyme and substrate molecules were practically identical for vesicles of identical size, they were found to increase with decreasing vesicle size. The kinetics of the α-chymotrypsin catalyzed hydrolysis of N-succinyl-Ala-Ala-Phe-7-amido-4-methylcoumarin (AMC) was evaluated following the increase of the absorption of the product 7-amino-4-methylcoumarin …

2019

Abstract Peer review is not only a quality screening mechanism for scholarly journals. It also connects authors and referees either directly or indirectly. This means that their positions in the network structure of the community could influence the process, while peer review could in turn influence subsequent networking and collaboration. This paper aims to map these complex network implications by looking at 2232 author/referee couples in an interdisciplinary journal that uses double blind peer review. By reconstructing temporal co-authorship networks, we found that referees tended to recommend more positively submissions by authors who were within three steps in their collaboration netwo…

Efficient Degradation of 4-Nitrophenol by Using Functionalized Porphyrin TiO2 Photocatalysts Under Visible Irradiation

2007

Abstract The novel porphyrins 5,10,15,20-tetra-[4-(3-phenoxy)-propoxy]phenyl porphyrin, H2Pp(a) and 5,10,15,20-tetra-[2-(3-phenoxy)-propoxy]phenyl porphyrin, H2Pp(b) and their corresponding copper(II) complexes CuPp(a), CuPp(b) were synthesized and characterized by using various spectroscopic techniques. The photocatalytic activity of polycrystalline TiO2 samples impregnated with H2Pp(a), H2Pp(b), CuPp(a) and CuPp(b) as sensitizers have been investigated by carrying out the photo-degradation of 4-nitrophenol (4-NP) as a probe reaction in aqueous suspension and under visible light. The maximum photocatalytic activity was obtained using TiO2 loaded with a monolayer of the copper porphyrin CuP…

Application of machine-vision techniques to fish-quality assessment

2012

Abstract Machine vision is a non-destructive, rapid, economic, consistent and objective inspection tool and is also an evaluation technique based on image analysis and processing with a variety of applications. We review the use of machine vision and imaging technologies for fish-quality assessment. This review updates and condenses a representative selection of recent research and industrial solutions proposed in order to evaluate the general trends of machine vision and image processing in the visible range applied for inspection of fish and fish products. In order to determine freshness and composition, it is necessary to measure and to evaluate size and volume, to estimate weight, to me…

Quaternary relaxations in sol-gel encapsulated hemoglobin studied via NIR and UV spectroscopy.

2007

In this work, we study the kinetics of the R --T transition in hemoglobin using a combination of near-infrared and near-ultraviolet spectroscopy. We use a sol-gel encapsulation protocol to decelerate the conformational transitions and to avoid spectral perturbations arising from ligand migration and recombination. We monitor two spectroscopic markers: band III in the near-IR, which is a fine probe of the heme pocket conformation, and the tryptophan band in the near-UV, which probes the formation of the Trpbeta37-Aspalpha94 hydrogen bond, characteristic of the T structure, at the critical alpha1beta2 subunit interface. The time evolution of these two bands is monitored after deoxygenation of…

The Medium-Depending Fluorescence of Quadrupolar Donor-Acceptor-Donor Substituted Distyrylbenzenes with High Two-Photon Absorption Cross-Sections

2006

ABSTRACT1,4-Distyrylbenzenes with terminal dialkylamino groups and a central 2,5-disubstitution with electron-accepting groups were prepared via twofold Horner-olefination. These chromophores with a quadrupolar donor-acceptor-donor substitution and C2-symmetry absorb in the violet to green region of the visible spectrum exhibit large two-photon-absorption cross-sections when irrdiated in the NIR. Whereas a variation of the solvent polarity only slightly alters the absorption spectra, the fluorescence appears to be highly responsive. Besides a positive solvatochromism, the emission is very sensitive towards protonation. Quenching or appearance of new emitting species depends on the substitut…

Oligophenylenevinylenes in Spatially Confined Nanochannels: Monitoring Intermolecular Interactions by UV/Vis and Raman Spectroscopy

2008

Perhydrotriphenylene-based channel-forming inclusion compounds (ICs) and thin films made of polyphenylenevinylene (PPV)-type oligomers with terminal alkoxy groups are investigated and compared in a combined experimental and theoretical approach. Interchromophore interactions and host-guest interactions are elucidated by UV/Vis and Raman spectroscopy. The impact of the local environment of the chromophore on the optical and photophysical properties is discussed in light of quantum-chemical calculations. In stark contrast to thin films where preferential side-by-side orientation leads to quenching of photoluminescence (PL) via non-emissive traps, the ICs are found to be attractive materials f…

Origin of the visible absorption in radiation-resistant optical fibers

2013

In this work we investigated the point defects at the origin of the degradation of radiation-tolerant optical fibers used in the visible part of the spectrum for plasma diagnostics in radiation environments. For this aim, the effects of γ -ray irradiation up to the dose of 10 MGy(SiO2) and post-irradiation thermal annealing at 550◦C were studied for a Fluorinedoped fiber. An absorption peaking around 2 eV is mainly responsible for the measured radiation-induced losses, its origin being currently debated in the literature. On the basis of the unchanging shape of this band with the radiation dose, its correlation with the 1.9 eV photoluminescent band and the thermal treatment results we assig…

Photosensibilisierte Oxidation von Lysozym bei Verschiedenen Wellenlängen

1974

The photooxidation of lysozyme in the presence of methylene blue, riboflavine, and bengal rose at differentpH values and wavelengths was studied. Monochromatic irradiation at shorter wavelengths (345 and 365 nm) is - in contrast to visible light - characterized by higher energy yields and lower oxygen consumption. This behavior suggests that the mechanism of photooxidation depends on the wavelength. The specific destruction of amino acid residues is also wavelength-dependent. Using visible light of 448 and 621 nm for riboflavine and methylene blue, respectively, we have confirmed the selective destruction of histidine and tryptophan atpH 7,0. The energy yield for the destruction of tryptoph…