Search results for "LIGHT"
showing 10 items of 3575 documents
Solubilization of an Organic Solute in Aqueous Solutions of Unimeric Block Copolymers and Their Mixtures with Monomeric Surfactant: Volume, Surface T…
2008
The ability of aqueous systems, formed by unimeric copolymers and their mixtures with a monomeric surfactant, in solubilizing large quantities of 1-nitropropane (PrNO2) was explored. The copolymers are F68 and L64, which differ for the hydrophilicity, and the surfactant is sodium dodecanoate. For a better understanding of the mechanism of solubilization, thermodynamic (volume and differential scanning calorimetry), spectroscopy (steady-state fluorescence), viscosity, and interfacial investigations were carried out. PrNO2 causes the micellization of the unimeric copolymer, and the required amount of PrNO2 depends on the composition, the copolymer nature, and the temperature. Large quantities…
Reversible Cluster Formation of Colloidal Nanospheres by Interparticle Photodimerization
2004
Crosslinked spherical nanoparticles based on trimethoxysilane monomers have been prepared by polycondensation in aqueous emulsion. These particles have been labeled chemically at their surface region with two different types of organic dye molecules (cinnamate, coumarin), which both are well known for their ability to undergo a reversible photodimerization if irradiated with light of a suitable wavelength. Upon irradiation of dilute solutions of these nanoparticles with UV light, the photodimerization of labels belonging to different colloidal nanoparticles caused the formation of large colloidal clusters consisting of chemically bound individual nanospheres. This process has been quantitat…
Structural Characterization of Zirconia Nanoparticles Prepared by Microwave-Hydrothermal Synthesis
2009
Nanocrystalline zirconia powders have been prepared by microwave-hydrothermal synthesis starting from aqueous solution of ZrOCl2·8H2O. Results of investigations on the aqueous suspension stability of the washed zirconia nanopowders by dynamic light scattering showed that the suspension, constituted by superaggregates of nanoparticles (131 ± 10 nm), was stable up to 15 days. Nanopowders were investigated by means of transmission electron microscopy and small angle x-ray scattering measurements which proved that the zirconia nanopowder is constituted by small primary nanoparticles of ca. 8 nm that agglomerate forming bigger aggregates of 50 ± 1 nm.
Static and dynamic light scattering by aqueous polyelectrolyte solutions: effect of molecular weight, charge density and added salt
1990
Abstract Aqueous solutions of quaternized poly(2-vinylpyridine) were investigated by static (SLS) and dynamic (DLS) light scattering over a wide range of polyelectrolyte, c pe , and salt concentrations, c s (10 −3 ≤ c pe ≤ 10 2 gl −1 , 10 −5.5 ≤ c s ≤ 10 −1 moll −1 ). Using DLS the cooperative diffusion coefficient D was measured as a function of c pe and c s . D exhibits a characteristic behaviour in each of three different concentration regimes. In the ‘dilute lattice’ regime, where λ = c pe c s ⪡ 1 , one diffusion coefficient is observed. In the transition regime, where λ ≈ 1, D increases with increasing polyelectrolyte concentration and a slow diffusive mode gradually appears. For λ ⪢ 1…
Single Molecule Spectroscopy of Oriented Recombinant Trimeric Light Harvesting Complexes of Higher Plants
2002
The bleaching dynamics of reconstituted single light-harvesting chlorophyll a/b investigated. The complexes containing one histidine6 tag per monomeric subunit were immobilised predominantly in a defined orientation with their symmetry axis perpendicular to a Ni-ion-containing surface allowing for the first time the examination of single LHCIIb in an aqueous environment. Most complexes exhibit photobleaching in one step, indicating coupling between the monomeric subunits leading to an energy transfer between adjacent subunits. Differences in bleaching behaviour between these and previous observations with single LHCIIb are discussed.
Sources of geomaterials in the Sicani Mountains during the Early Middle Ages: A case study of Contrada Castro, central western Sicily
2022
From 2017, an unknown rural settlement in Contrada Castro at Corleone (Palermo Province, western Sicily) was investigated as part of the `Harvesting Memories Project¿. The stratigraphic sequence, supported by radiocarbon dating, has demonstrated a reoccupation of a pre-Roman site during the transition between the Byzantine and Islamic periods. In particular, the main occupation occurred in the late 8th¿9th century when pottery kilns and a probable warehouse were constructed. During the 10th¿11th century, a new structure with different orientations replaced the previous buildings that had already collapsed. Specifically focusing on a perspective of the household production and its relationsh…
Persistenza della thòlos nell’architettura contemporanea
2020
La thòlos è una costruzione che può essere assunta come un inizio dell’architettura e che definisce principi che stanno oltre la storia e l’archeologia: rappresenta un archetipo legato al mondo litico, proveniente dall’oriente e diffuso sin dall’età greco-arcaica in tutto il Mediterraneo. Custodisce memorie di epoche mitiche e forme che affiorano con continuità nell’architettura, attraversa la storia e persiste nella modernità soprattutto negli spazi di culto e celebrativi. Lo spazio della thòlos consente di riprendere nel progetto contemporaneo alcuni temi i cui esiti conducono ad una architettura che è in antitesi alla continuità visiva interno-esterno e all’assenza di confini, che all’in…
Daylighting offices: A first step toward an analysis of photobiological effects for design practice purposes
2014
Abstract The research presented in this paper reports an analysis of daylight in three offices with different exposures and characteristics located in Naples (Italy). The goal was to fully investigate daylight characteristics, also considering the circadian impact of daylight entering these offices, with the hope to develop guidelines to better assess daylight quality in built environments. One of the main findings of this research is that the spectral distributions and CCTs of the light reaching the eye of a person seated at the desk in these offices are similar irrespective of the offices' different characteristics (dimensions, surfaces' spectral reflectances, external obstructions, etc.)…
Smart lighting in a historic context: a case study
2017
Purpose The purpose of this paper is to address a project for lighting an old town in Italy. Its originality lies in the holistic approach that aims to fulfil several objectives. One is to reduce energy consumption by using efficient lamps and advanced control systems; the second one is to make the network viable and useful for many purposes by integrating ICT devices; the third one is to provide a new identity to the older part of the city by using new technologies and design concepts; while the last one is to ensure street and pedestrian safety according to codes and standards. Design/methodology/approach The plan of the city of Bagheria and the stock of luminaires of the city are analys…
A laboratory setup for the evaluation of the effects of BACS and TBM systems on lighting
2015
The paper focuses on the evaluation of the impact of Building Automation Control Systems (BACS) and Technical Building Management (TBM) systems on the performance of the lighting system in a residential building. In particular, this work shows a laboratory setup, installed at the DEIM of the University of Palermo, for simulating a typical apartment. The paper describes the laboratory, the lighting system and the BAC system installed and the test facility for evaluating the electricity consumption in presence and in absence of automation. The laboratory has been built within a research project funded by the Italian Minister of University and Research in the framework of the PON Smart Cities …