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Electromagnetic Radiation (electromagnetic + radiation)
Selected AbstractsThe life of , and ,,A tutorial review of the ubiquitous use of these symbols in Zeeman and magnetic-resonance spectroscopyCONCEPTS IN MAGNETIC RESONANCE, Issue 2 2008John Ashley Weil Abstract Certain concepts and symbolism as applied to electromagnetic radiation and especially the concept of photons are discussed and (perhaps) clarified. A useful summary of the properties of photons is provided, and the concept of polarization is discussed. In particular, the common usage in Zeeman and magnetic-resonance (EPR and NMR) spectroscopy of the symbols , and , is examined herein, both from the historical viewpoint and the scientific standpoint, and certain errors and fallacies are brought to attention. Brief reference to relevant recent work published on dynamic nuclear polarization and on pulse EPR is included. © 2008 Wiley Periodicals, Inc.Concepts Magn Reson Part A 32A: 134,142, 2008. [source] Spatial Patterning of the , -Phase in Poly(9,9-dioctylfluorene): A Metamaterials-Inspired Molecular Conformation Approach to the Fabrication of Polymer Semiconductor Optical StructuresADVANCED FUNCTIONAL MATERIALS, Issue 20 2009Gihan Ryu Abstract Materials in which sub-wavelength physical structures, rather than variations in chemical composition, are used to modify the nature of their interaction with electromagnetic radiation form the promising new class of metamaterials. For molecular materials one has an intriguing alternative, namely structuring the conformation or physical geometry of the molecule. In order for this to be an effective methodology one needs the change in conformation i) to engender a significant change in electromagnetic properties and ii) to be spatially controllable to allow patterning of practical structures. In this paper the potential of such an approach is demonstrated through spatial patterning, via masked solvent vapor exposure, of the , -phase conformation in poly(9,9-dioctylfluorene) (PFO). Significantly the conformation change approach preserves a planar film format and is found not to negatively impact on optical gain properties, both very attractive features for optoelectronic and photonic lightwave circuit applications. As a specific demonstration the ability to spatially control the lasing wavelength for samples in which a , -phase conformation is selectively patterned in a glassy PFO film spin coated atop a one-dimensional distributed-feedback grating etched into a spectrosil substrate is shown. [source] The EMF uncertainty problem related to mobile phones: where do consumers place their trust?INTERNATIONAL JOURNAL OF CONSUMER STUDIES, Issue 2 2010Lisbet Berg Abstract This paper addresses the uncertainty problem, i.e. cases characterized by lack of knowledge or scientific uncertainty. In such situations, it can be hard for consumers to ,voice' or practise consumer power. One field characterized by the uncertainty problem is electromagnetic radiation. An explicit goal of this study has been to articulate Norwegian consumers' practices, attitudes and beliefs regarding electromagnetic radiation from mobile phones to public authorities and consumer policy makers. The study was based on 1000 telephone interviews collected in 2008. Today, experts disagree on the potential health effects of radiation from electromagnetic fields (EMF), as well as standards for safe limits of exposure to mobile phones, base stations and wireless telecommunication systems. In addition, complicated technology and extremely rapid product development and diffusion leave consumers' security considerations to their own beliefs and trust. Whether or not electromagnetic radiation from mobile phones constitutes a health hazard will not be addressed in this paper. Rather, it will focus on how consumers react to this situation of uncertainty. The material reveals four main ways in which consumers can solve what we have named the EMF uncertainty problem: the confident and comfortable way, the sceptical and cautious way, the responsible and good citizen way, and finally, the neglecting way. The paper also discusses the precautionary principle related to EMF. Who should be precautionary: the public authorities, the mobile phone industry or the consumers themselves? We believe that a consistent governmental precautionary policy in combination with consumers taking their own precautionary measures is a viable solution. In this way, all consumers would be addressed and aided when navigating this field of uncertainty. [source] In vitro evaluation of sun protection factors of sunscreen agents using a novel UV spectrophotometric techniqueINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 4 2008M. D. Bleasel Synopsis A method for the in vitro determination of low- and high-value sun protection factors (SPF) of sunscreens using artificial substrates and a novel pseudo double beam (PDB) mode of operation of a standard double beam UV spectrophotometer is described. The method allows transmittance to be calculated from detector responses of reference and sample beams measured at different gain levels and facilitates the accurate quantification of low levels of electromagnetic radiation transmitted through highly absorbing samples. The spectrophotometer was modified to hold quartz diffusing plates on which a substrate [TransporeÔ adhesive tape or human stratum corneum obtained from a skin surface biopsy (SSB)] and the sunscreens to be tested were applied. The PDB mode of operation increased the effective linear range of the detector response of the spectrophotometer by a factor of approximately 20000-fold, enabling the in vitro SPF determination technique to be applied to both high and low SPF value sunscreens. Eight commercial sunscreens with known SPF values ranging from 4 to 77, previously determined by in vivo methods, were tested in vitro using both test substrates and correlations between the in vivo and in vitro values were determined. SPF values determined using the in vitro method correlated well with the known in vivo results (TransporeÔ tape, R2 = 0.611; SSB, R2 = 0.7928). The in vitro SPF obtained for one of the tested products differed substantially from the cited in vivo SPF value. Independent in vitro and in vivo re-evaluation of the SPF of this product matched the value predicted by the present method much more closely than the originally cited in vivo value. All determined SPFs were ordered correctly in comparison to in vivo ranking and the technique appeared to correctly identify a sunscreen that had a labelled SPF value that was significantly higher than its true SPF. Résumé Une méthode destinée à déterminer in vitro les facteurs de protection solaire (SPF) d'écrans solaires de faible et haut indice est décrite. Elle met en ,uvre des substrats artificiels et un nouveau mode opératoire reposant sur l'utilisation du pseudo double faisceau (PDB) d'un spectrophotomètre UV double faisceau standard. La méthode permet le calcul de la transmittence à partir des réponses du détecteur de référence et la mesure en simple faisceau à différents niveaux de gain facilitant ainsi la quantification précise des faibles niveaux de radiation électromagnétique (EMR) transmis à travers des échantillons hautement absorbants. Le spectrophotomètre a été modifié de façon à fixer des plaques diffusantes en quartz sur lesquelles un substrat (ruban adhésif Transport TM ou du stratum corneum humain obtenu à partir de biopsie de surface de peau (SSB) et les écrans solaires testés ont été appliqués. Le mode opératoire PTB augmente la gamme linéaire effective de la réponse du détecteur du spectrophotomètre d'un facteur approximatif 20.000 permettant, à cette technique de détermination des SPF in vitro, d'être appliquée à la fois sur les écrans solaires de haut et bas SPF. Huit écrans solaires commerciaux de SPF connus allant de 4 à 77, préalablement déterminés par des méthodes in vivo, ont été testés in vitro en utilisant les deux substrats, et les corrélations entre les valeurs in vivo et in vitro ont été déterminées. Les valeurs SPF déterminées en utilisant la méthode in vitro est bien corrélée avec les résultats in vivo connus (ruban transport, R2 = 0.611; SSB, R2 = .7928). Le SPF in vitro pour l'un des produits testés diffère fortement des valeurs SPF citées in vivo. Une réévaluation indépendante des SPF in vitro et in vivo de ce produit ajuste la valeur prédite par la présente méthode de façon beaucoup plus proche que la valeur originale citée in vivo. Tous les SPF ainsi déterminés sont ordonnés correctement en comparaison au classement in vivo et la technique semble identifier correctement un écran solaire qui possède un SPF libellé significativement plus haut que son vrai SPF. [source] Application of Surface Photo Charge Effect for Milk Quality ControlJOURNAL OF FOOD SCIENCE, Issue 7 2009O. Ivanov ABSTRACT:, The potential difference induced by the interaction of samples with electromagnetic radiation in the visible region is used for food characterization. In this article we show that the above effect can be applied for the understanding of specific reactions and processes taking place in milk such as change of the acidity and changes caused by an added reagent. We also propose a technique for instantaneous detection of inhibitors of starter bacteria in milk. We suggest possible methods for quality control of milk and other foods. Instantaneous results, practically no expenses for consumables, and possibilities for field measurements will be some of the advantages of this approach. [source] Microwave-Assisted Synthesis of Fine Particle Oxides Employing Wet Redox MixturesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2002Solomon Sundar Manoharan Interaction of electromagnetic radiation with a physical mixture of metal nitrates and amides/hydrazides is observed to initiate high-temperature reactions, useful for realizing several high-temperature ceramic materials. A judicious choice of such redox mixtures undergoes exothermic reactions when they couple with microwave radiation. The coupling of electromagnetic radiation with metal salts and amides/hydrazides depends on the dielectric properties of the individual components in the reaction mixture. The approach has been used to prepare ,-Fe2O3, Fe3O4, MgCr2O4, ,-CaCr2O4, and La0.7Ba0.3MnO3. [source] Triple Dumbbell Polymer Nanolayer Frequency ResponseMACROMOLECULAR THEORY AND SIMULATIONS, Issue 6 2008Steven Grisafi Abstract A triple dumbbell sandwich model is developed to predict the frequency response of an interface created within nanolayer polymer films. One dumbbell different from two others is layered between the other two. The interactions among the macromolecules are modeled using Hooke's law for the intramolecular, intermolecular, and an applied external force. The external force is meant to describe incident electromagnetic radiation. The transient response of the system in the frequency domain is presented along with the steady-state response. The frequency response for the central dumbbell differs from its two partners suggesting that birefringence of incident radiation is possible. The phase angle of the oscillations for the two different polymer species shows that the frequency of incident light would be shifted differently by the two when it traverses the polymer film. [source] Compact angularly stable frequency selective surface using hexagonal fractal configurationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2009Wentao T. Wang Abstract A compact bandstop frequency selective surface (FSS) using fractal structure is proposed. This flexuous design elongates the cell perimeter of the ring-shaped FSS, which means the cell size gets smaller at the same resonance frequency. Furthermore, the unit cells adopt regular hexagon and the array employs equilateral triangle form. Because of its symmetric configuration, good frequency stability has been achieved for both horizontal and vertical polarizations at different oblique angles. For the stable bandstop character, this FSS can be used for protecting the staff of S-band radars against electromagnetic radiation, while the 900/1800/1900 MHz mobile bands and the 5.2/5.8 GHz wireless local area network signals are not affected. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2541,2544, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24676 [source] Light-sensitive Intelligent Drug Delivery Systems,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009Carmen Alvarez-Lorenzo Drug delivery systems (DDS) capable of releasing an active molecule at the appropriate site and at a rate that adjusts in response to the progression of the disease or to certain functions/biorhythms of the organism are particularly appealing. Biocompatible materials sensitive to certain physiological variables or external physicochemical stimuli (intelligent materials) can be used for achieving this aim. Light-responsiveness is receiving increasing attention owing to the possibility of developing materials sensitive to innocuous electromagnetic radiation (mainly in the UV, visible and near-infrared range), which can be applied on demand at well delimited sites of the body. Some light-responsive DDS are of a single use (i.e. the light triggers an irreversible structural change that provokes the delivery of the entire dose) while others able to undergo reversible structural changes when cycles of light/dark are applied, behave as multi-switchable carriers (releasing the drug in a pulsatile manner). In this review, the mechanisms used to develop polymeric micelles, gels, liposomes and nanocomposites with light-sensitiveness are analyzed. Examples of the capability of some polymeric, lipidic and inorganic structures to regulate the release of small solutes and biomacromolecules are presented and the potential of light-sensitive carriers as functional components of intelligent DDS is discussed. [source] Photonics in photovoltaic systemsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2008Andreas Gombert Abstract This paper gives an overview on photonics for photovoltaic systems. Starting from the spectral and angular distribution of the electromagnetic radiation from the sun, many important optical approaches how to improve the efficiency of solar cells are presented and discussed. Topics include antireflective coatings, various light trapping structures, refractive, reflective and fluorescent concentrators, and components for spectral management. The theoretical background is shortly described and examples of the experimental and also of the commercial realisation are given. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Spectroscopic ellipsometry and vector network analysis for determination of the electromagnetic response in two wavelength regionsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2008C. Åkerlind Abstract In this work, spectroscopic ellipsometry and vector network analysis are used to determine the electromagnetic response of three samples, an epoxy polymer, a sample with ferrit-based nanoparticles in a polymer matrix and silicon, in the wavelength ranges 0.4-30 ,m and 0.75-7.59 cm. Both methods measure amplitude and phase changes due to interaction with a sample and can be used to measure the full complex-valued dielectric response to electromagnetic radiation. The data from the two methods show similar levels of the response at the two ends of the spectral gap between the ranges of the two methods. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Electroactive composite systems containing high conductive polymer layers on poly(ethylene) porous films,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9-10 2006G. K. Elyashevich Abstract New composite electroactive materials containing conducting polymers were elaborated by oxidative polymerization of aniline and pyrrole onto porous poly(ethylene) films. The morphology of the conducting phase on the surface of the composites was investigated by scanning electron microscopy. The influence of preparation method and porous support structure on electric and mechanical properties of the composite materials was studied. The correlation between the composites electroconductivity and the absorbance of electromagnetic radiation in the IR region was observed. It was found that gas separation and ion-exchange membrane properties of the composites strongly depend on their conductivity and content of conducting component. Copyright © 2006 John Wiley & Sons, Ltd. [source] Electrodynamics in accelerated frames revisitedANNALEN DER PHYSIK, Issue 10 2010J.W. Maluf Abstract Maxwell's equations are formulated in arbitrary moving frames by means of tetrad fields, which are interpreted as reference frames adapted to observers in space-time. We assume the existence of a general distribution of charges and currents in an inertial frame. Tetrad fields are used to project the electromagnetic fields and sources on accelerated frames. The purpose is to study several configurations of fields and observers that in the literature are understood as paradoxes. For instance, are the two situations, (i) an accelerated charge in an inertial frame, and (ii) a charge at rest in an inertial frame described from the perspective of an accelerated frame, physically equivalent? Is the electromagnetic radiation the same in both frames? Normally in the analysis of these paradoxes the electromagnetic fields are transformed to (uniformly) accelerated frames by means of a coordinate transformation of the Faraday tensor. In the present approach coordinate and frame transformations are disentangled, and the electromagnetic field in the accelerated frame is obtained through a frame (local Lorentz) transformation. Consequently the fields in the inertial and accelerated frames are described in the same coordinate system. This feature allows the investigation of paradoxes such as the one mentioned above. [source] Exposure of human peripheral blood lymphocytes to electromagnetic fields associated with cellular phones leads to chromosomal instabilityBIOELECTROMAGNETICS, Issue 2 2003Maya Mashevich Abstract Whether exposure to radiation emitted from cellular phones poses a health hazard is at the focus of current debate. We have examined whether in vitro exposure of human peripheral blood lymphocytes (PBL) to continuous 830 MHz electromagnetic fields causes losses and gains of chromosomes (aneuploidy), a major "somatic mutation" leading to genomic instability and thereby to cancer. PBL were irradiated at different average absorption rates (SAR) in the range of 1.6,8.8 W/kg for 72 hr in an exposure system based on a parallel plate resonator at temperatures ranging from 34.5,37.5 °C. The averaged SAR and its distribution in the exposed tissue culture flask were determined by combining measurements and numerical analysis based on a finite element simulation code. A linear increase in chromosome 17 aneuploidy was observed as a function of the SAR value, demonstrating that this radiation has a genotoxic effect. The SAR dependent aneuploidy was accompanied by an abnormal mode of replication of the chromosome 17 region engaged in segregation (repetitive DNA arrays associated with the centromere), suggesting that epigenetic alterations are involved in the SAR dependent genetic toxicity. Control experiments (i.e., without any RF radiation) carried out in the temperature range of 34.5,38.5 °C showed that elevated temperature is not associated with either the genetic or epigenetic alterations observed following RF radiation,the increased levels of aneuploidy and the modification in replication of the centromeric DNA arrays. These findings indicate that the genotoxic effect of the electromagnetic radiation is elicited via a non-thermal pathway. Moreover, the fact that aneuploidy is a phenomenon known to increase the risk for cancer, should be taken into consideration in future evaluation of exposure guidelines. Bioelectromagnetics 24:82,90, 2003. © 2003 Wiley-Liss, Inc. [source] Effects of electromagnetic radiation from a cellular telephone on the oxidant and antioxidant levels in rabbitsCELL BIOCHEMISTRY AND FUNCTION, Issue 4 2002M. Kemal Irmak Abstract The number of reports on the effects induced by electromagnetic radiation (EMR) in various cellular systems is still increasing. Until now no satisfactory mechanism has been proposed to explain the biological effects of this radiation. Oxygen free radicals may play a role in mechanisms of adverse effects of EMR. This study was undertaken to investigate the influence of electromagnetic radiation of a digital GSM mobile telephone (900,MHz) on oxidant and antioxidant levels in rabbits. Adenosine deaminase, xanthine oxidase, catalase, myeloperoxidase, superoxide dismutase (SOD) and glutathione peroxidase activities as well as nitric oxide (NO) and malondialdehyde levels were measured in sera and brains of EMR-exposed and sham-exposed rabbits. Serum SOD activity increased, and serum NO levels decreased in EMR-exposed animals compared to the sham group. Other parameters were not changed in either group. This finding may indicate the possible role of increased oxidative stress in the pathophysiology of adverse effect of EMR. Decreased NO levels may also suggest a probable role of NO in the adverse effect. Copyright © 2002 John Wiley & Sons, Ltd. [source] Photolysis of rac -Leucine with Circularly Polarized Synchrotron RadiationCHEMISTRY & BIODIVERSITY, Issue 6 2010Abstract Amino acids that pass the RNA machinery in living organisms occur in L -configuration. The question on the evolutionary origin of this biomolecular asymmetry remains unanswered to this day. Amino acids were detected in artificially produced interstellar ices, and L -enantiomer-enriched amino acids were identified in CM-type meteorites. This hints at a possible interstellar/circumstellar origin of the amino acids themselves as well as their stereochemical asymmetry. Based upon the current knowledge about the occurrence of circularly-polarized electromagnetic radiation in interstellar environments, we subjected rac -leucine to far-UV circularly-polarized synchrotron radiation. Asymmetric photolysis was followed by an analysis in an enantioselective GC/MS system. Here, we report on an advanced photolysis rate of more than 99% for leucine. The results indicate that high photolysis rates can occur under the chosen conditions, favoring enantioselective photolysis. In 2014, the obtained results will be reexamined by cometary mission Rosetta. [source] | ||||||||||||||||||||||