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Resonance
Kinds of Resonance Terms modified by Resonance Selected AbstractsTHE APPLICATION OF ELECTRON SPIN RESONANCE AS A GUIDE TO THE MATURATION AND TYPING OF ORGANIC MATTER IN THE NORTH SEAJOURNAL OF PETROLEUM GEOLOGY, Issue 1 2003R. A. McTavish In early electron spin resonance (ESR) analysis of North Sea wells, maturation of organic matter (OM) was expressed in terms of maximum palaeotemperature (MPT) based on North American calibrations that did not consider the influences of kerogen composition or overpressure. In the North Sea, the MPTs were anomalous in overpressured sequences and relative to other indices of OM maturation such as vitrinite reflectance, so the ESR method was abandoned there in geochemical studies. However, early empirical study of North Sea ESR data indicated that, in relation to functions that linked temperature and pore pressure, some ESR parameters were predictable without reference to MPTs. In order to re-evaluate ESR parameters as indices of OM maturation, the physical factors (temperature and pressure) which affect OM maturation are related in the present paper to the ESR parameters "g" (spectral position) and Ng (spin density) at six well locations in the northern North Sea. A third ESR parameter, W (line width), is not an effective guide to maturation levels due to its complex relationship to the physical factors and kerogen types. However, cross-plots of W versus "g" and Ng appear to be as effective as pyrolysis for kerogen typing. Levels of maturation investigated in the North Sea wells range through the equivalent vitrinite reflectance values of about 0.50,1.50%. The values of "g" and Ng have been differentiated for kerogen type, but undifferentiated values of "g" have also been studied. Regression analysis has shown that there are linear relationships between the ESR parameters "g" and Ng, and the physical factors present-day temperature (To), "effective" temperature (Te), and differential pressure (Pd). Correlation coefficients for both "g" (undifferentiated and differentiated) and Ng (differentiated) relative to the physical factors are high; the highest values are for "g" and Ng relative to Te and Pd (r =,0.950 for "g" differentiated or undifferentiated, r = 0.944,0.976 for Ng differentiated, respectively). However, correlation coefficients were lower for "g" and Ng relative to To. More frequent high correlation coefficients and larger sample populations suggest that "g" (undifferentiated) is a more reliable index of OM maturation than Ng(differentiated). However, the estimation of levels of OM maturation is improved if both indices are used together. The ESR method appears to be effective both for estimating levels of OM maturation and for kerogen typing. It has a number of potential advantages over other geochemical methods: firstly, it is more sensitive for estimating OM maturation than most other methods; secondly, it can be used to analyze organic matter which is as old as Proterozoic; thirdly, it does not destroy the samples analyzed. [source] SEQUENCE AND STRUCTURAL ANALYSIS OF ,-CARRAGEENAN-DERIVED OLIGOSACCHARIDES BY TWO-DIMENSIONAL NUCLEAR MAGNETIC RESONANCE,JOURNAL OF PHYCOLOGY, Issue 4 2010Wei Zhang ,-Carrageenan was hydrolyzed with mild hydrochloric acid and separated into a series of oligosaccharides, the sequences and structures of which were investigated by double-quantum filtered correlation spectroscopy (DQF-COSY), total correlation spectroscopy (TOCSY), heteronuclear multiple-quantum coherence (HMQC), and heteronuclear multiple-bond correlation (HMBC) techniques, respectively. The chemical structures and conformations of the individual sugar residues were identified, as well as the sequential connectivity of the oligosaccharides. The interresidue nuclear Overhauser effects (NOEs)/rotating frame Overhauser effects (ROEs) revealed an ordered helical structure of the carrageenan oligosaccharide chains. Therefore, a general two-dimensional (2-D) NMR methodology for the unambiguous sequence and structure analysis of ,-carrageenan-derived oligosaccharides was established in this study. [source] MAGNETIC RESONANCE IN SURGICAL ONCOLOGY: I , ON THE ORIGIN OF THE SPECTRUMANZ JOURNAL OF SURGERY, Issue 6 2005Laurence Gluch The discovery of the phenomenon of nuclear magnetic resonance occurred just 60 years ago. The profusion of subsequent discoveries in this domain has led to the development of magnetic resonance spectroscopy , refined as an analytical tool to discern molecular structure , and magnetic resonance imaging, a cornerstone of modern radiology. Observable alterations in cellular structure and metabolism can be discerned using the non-destructive chemical analysis of magnetic resonance spectroscopy in vitro or in vivo. Differences may thus be discerned between malignant and normal tissues. [source] MAGNETIC RESONANCE IN SURGICAL ONCOLOGY: II , LITERATURE REVIEWANZ JOURNAL OF SURGERY, Issue 6 2005Laurence Gluch Ex vivo and in vivo applications of magnetic resonance spectroscopy have been developed which aid in distinguishing malignant from normal tissues. Studies of breast, colon, cervix, oesophageal and prostate cancer reveal both the successes and failings of present technology. Verification that these non-invasive tests might supplant conventional histology in obtaining spatial diagnostic and chemical prognostic information remains for the time being illusive. [source] COLOUR ATTRIBUTES OF MEDIEVAL WINDOW PANES: ELECTRON PARAMAGNETIC RESONANCE AND PROBE MICROANALYSES ON STAINED GLASS WINDOWS FROM PAVIA CARTHUSIAN MONASTERY*ARCHAEOMETRY, Issue 2 2005C. B. AZZONI Stained glass windows from the Carthusian Monastery of Pavia, dating back to the 15th century, were studied by combining two analytical techniques: electron probe micro-analysis (EPMA) and electron paramagnetic resonance (EPR). Chemical compositions and oxidation states of the transition ions, present as minor elements, were investigated by EPMA and EPR, respectively, in order to ascertain the role played by chromophorous ions in the glass coloration. The investigated glass can be defined as K,Ca glass, and the panes with red, green and blue colours were produced using flashing techniques. [source] Book review: Electron Paramagnetic Resonance: Elementary Theory and Practical Applications.CONCEPTS IN MAGNETIC RESONANCE, Issue 4 20082nd edition. No abstract is available for this article. [source] Design of an MR-compatible piezoelectric actuator for MR elastographyCONCEPTS IN MAGNETIC RESONANCE, Issue 4 2002Kai Uffmann Abstract Magnetic Resonance (MR) elastography is a method for measuring tissue elasticity via phase images acquired with an MR scanner. The propagation of periodic mechanical waves through the tissue can be captured by means of a modified phase contrast sequence. These waves are generated with a mechanical oscillator (actuator) and coupled into the tissue through the skin. The actuator must be capable of generating a sinusoidal excitation with excellent phase and amplitude stability, while not disturbing the MR imaging process. In this work, an actuator based on a piezoelectric principle was developed. Based on the imaging evaluation of several material samples, the housing for the piezoelectric ceramic was constructed of aluminum. Smaller parts of the housing were manufactured from brass and titanium to fulfill the mechanical constraints. A lever was used to transfer the oscillation generated by the piezoelectric ceramic to the point of excitation. The lever amplifies the piezoelectric motion, allowing for a more compact design. Three different lever designs were characterized by an acceleration sensor both outside and inside the magnet. It was shown that the rigidity of the lever, as determined by its material and form, was decisive in determining the resonant frequency of the system and therefore the maximum practical frequency of operation. It was also shown that the motion of the oscillator is unaffected by the electromagnetic fields of the MR imager. The final design can be placed directly in the magnet bore within a few centimeters of the tissue volume to be imaged without generating significant artifacts. An amplitude range of 0,1 mm in the frequency range from 0 to over 300 Hz was achieved, sufficient for performing most MR elastography applications. © 2002 Wiley Periodicals, Inc. Concepts in Magnetic Resonance (Magn Reson Engineering) 15: 239,254, 2002 [source] Simple NMR-mouse with a bar magnet,CONCEPTS IN MAGNETIC RESONANCE, Issue 4 2002B. Blümich Abstract A new concept of the NMR Mobile Universal Surface Explorer (NMR-MOUSE) using simple bar magnets instead of u-shaped magnets is described. The magnetic field profiles are comparatively homogeneous in extended lateral planes, and close to the magnet pole face the axial gradient is nearly constant. Different geometric arrangements of figure-8 coils adapted to the sample geometry are described. Simulations and measurements of the magnetic field from the magnets and the radio frequency coils are discussed. © 2002 Wiley Periodicals, Inc. Concepts in Magnetic Resonance (Magn Reson Engineering) 15: 255,261, 2002 [source] Use of mutually inductive coupling in probe design,CONCEPTS IN MAGNETIC RESONANCE, Issue 4 2002D.I. Hoult Abstract An analysis is presented of mutually inductive coupling in probe design. It is assumed that near field couplings predominate and that lumped constants may therefore be employed. Using three published designs as examples, analytic techniques are presented for assessing B1 field strength, losses, and signal-to-noise ratio in increasingly complex situations. The perturbing effect of the B1 field from a matching coil is examined and it is shown that if the coil is too close to the sample there can be an asymmetry introduced in the rotating frame B1 field. It is then shown that such asymmetries are potentially a general feature of inductively coupled, loaded coils. The importance of suppressing unwanted resonances is highlighted if tuning and matching are to be orthogonal, a potential advantage of mutually inductive matching. Finally, a lumped-constant simulation is briefly described for those situations where an analytic approach becomes too cumbersome. © 2002 Wiley Periodicals, Inc. Concepts in Magnetic Resonance (Magn Reson Engineering) 15: 262,285, 2002 [source] Current density mapping approach for design of clinical magnetic resonance imaging magnetsCONCEPTS IN MAGNETIC RESONANCE, Issue 3 2002Stuart Crozier Abstract Novel current density mapping (CDM) schemes are developed for the design of new actively shielded, clinical magnetic resonance imaging (MRI) magnets. This is an extended inverse method in which the entire potential solution space for the superconductors has been considered, rather than single current density layers. The solution provides an insight into the required superconducting coil pattern for a desired magnet configuration. This information is then used as an initial set of parameters for the magnet structure, and a previously developed hybrid numerical optimization technique is used to obtain the final geometry of the magnet. The CDM scheme is applied to the design of compact symmetric, asymmetric, and open architecture 1.0,1.5 T MRI magnet systems of novel geometry and utility. A new symmetric 1.0-T system that is just 1 m in length with a full 50-cm diameter of the active, or sensitive, volume (DSV) is detailed, as well as an asymmetric system in which a 50-cm DSV begins just 14 cm from the end of the coil structure. Finally a 1.0-T open magnet system with a full 50-cm DSV is presented. These new designs provide clinically useful homogeneous regions and have appropriately restricted stray fields but, in some of the designs, the DSV is much closer to the end of the magnet system than in conventional designs. These new designs have the potential to reduce patient claustrophobia and improve physician access to patients undergoing scans. © 2002 Wiley Periodicals, Inc. Concepts in Magnetic Resonance (Magn Reson Engineering) 15: 208,215, 2002 [source] Novel software architecture for rapid development of magnetic resonance applicationsCONCEPTS IN MAGNETIC RESONANCE, Issue 3 2002Josef Debbins Abstract As the pace of clinical magnetic resonance (MR) procedures grows, the need for an MR scanner software platform on which developers can rapidly prototype, validate, and produce product applications becomes paramount. A software architecture has been developed for a commercial MR scanner that employs state of the art software technologies including Java, C++, DICOM, XML, and so forth. This system permits graphical (drag and drop) assembly of applications built on simple processing building blocks, including pulse sequences, a user interface, reconstruction and postprocessing, and database control. The application developer (researcher or commercial) can assemble these building blocks to create custom applications. The developer can also write source code directly to create new building blocks and add these to the collection of components, which can be distributed worldwide over the internet. The application software and its components are developed in Java, which assures platform portability across any host computer that supports a Java Virtual Machine. The downloaded executable portion of the application is executed in compiled C++ code, which assures mission-critical real-time execution during fast MR acquisition and data processing on dedicated embedded hardware that supports C or C++. This combination permits flexible and rapid MR application development across virtually any combination of computer configurations and operating systems, and yet it allows for very high performance execution on actual scanner hardware. Applications, including prescan, are inherently real-time enabled and can be aggregated and customized to form "superapplications," wherein one or more applications work with another to accomplish the clinical objective with a very high transition speed between applications. © 2002 Wiley Periodicals, Inc. Concepts in Magnetic Resonance (Magn Reson Engineering) 15: 216,237, 2002 [source] Late Presentation of Pulmonary Valve Stenosis Confirmed by Cardiovascular Magnetic ResonanceCONGENITAL HEART DISEASE, Issue 3 2008Didier Locca MD ABSTRACT We describe the case of a 70-year-old man who presented with increasing exertional dyspnea. He was found to have an ejection systolic murmur and evidence of right ventricular outflow tract obstruction, with a peak velocity of 4.5 m/s recorded by transthoracic Doppler echocardiography. Cardiovascular magnetic resonance showed right ventricular hypertrophy, pulmonary valve stenosis, peak recorded velocity 4.2 m/s, with thickened pulmonary valve leaflets of reduced mobility, and poststenotic dilatation of the main pulmonary artery. The case illustrates that severe pulmonary valve stenosis can present late in life and that cardiovascular magnetic resonance can be useful in clarifying nature and level of right ventricular outflow tract obstruction in an adult. [source] Validation of the Peak to Mean Pressure Decrease Ratio as a New Method of Assessing Aortic Stenosis Using the Gorlin Formula and the Cardiovascular Magnetic Resonance-Based Hybrid MethodECHOCARDIOGRAPHY, Issue 4 2007Dariusch Haghi M.D. Background: We sought to validate the recently introduced peak to mean pressure decrease ratio (PMPDR), using the Gorlin formula and a hybrid method which combines cardiovascular magnetic resonance (CMR)-derived stroke volume with transaortic Doppler measurements to calculate aortic valve area (AVA). Methods: Data analysis in 32 patients with severe (AVA <= 0.75 cm2) or moderate aortic stenosis who had prospectively been entered into our aortic stenosis database. Results: Gorlin-derived AVA was 0.61 ± 0.10 cm2 in severe and 0.92 ± 0.14 cm2 in moderate aortic stenosis (P < 0.01). Corresponding values for PMPRD were 1.61 ± 0.10 and 1.73 ± 0.18, respectively (P < 0.05). Sensitivity, specificity, positive and negative predictive values for PMPDR <1.5 to predict severe aortic stenosis were 0.12, 0.92, 0.67, and 0.44 as assessed by the Gorlin formula. Conclusions: Using the Gorlin formula as the reference standard, our study confirms results of a previously reported study on the performance of PMPDR for assessment of aortic stenosis. [source] Area-Specific Resonance of Excitatory Networks in Neocortex: Control by Outward CurrentsEPILEPSIA, Issue 8 2007Manuel A. Castro-Alamancos Summary:, During disinhibition or low [Mg++]o buffer, 7,14 Hz (,10 Hz) oscillations are generated by excitatory networks of interconnected pyramidal cells in motor (agranular) cortex but are absent in barrel (granular) cortex. Here we studied if the inability of barrel cortex to produce ,10 Hz oscillations during these conditions is because barrel cortex networks lack the necessary cellular mechanisms or, alternatively, because those mechanisms are inhibited by outward currents. The results show that blockers of slowly inactivating voltage-dependent K+ currents unmask ,10 Hz oscillations in barrel cortex, and this occurs in unison with the unmasking of intrinsic inward Ca++ currents that are kept suppressed by the outward currents. Moreover, the ,10 Hz oscillations unmasked in barrel cortex occur independently in upper and lower layers indicating that the ,10 Hz oscillation mechanisms are kept suppressed in multiple networks. The results reveal that the propensity of distinct excitatory networks of neocortex to generate epileptiform oscillatory activities is controlled by outward currents. [source] Comparison of Cyclodextrin-Dipeptide Inclusion Complexes in the Absence and Presence of Urea by Means of Capillary Electrophoresis, Nuclear Magnetic Resonance and Molecular ModelingEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2007Benjamin Waibel Abstract The use of capillary electrophoresis (CE) modified with cyclodextrin (CD) for the separation of stereoisomers of peptides is well established. To increase the solubility of ,-CD, urea is often added to the buffer which may influence the complexation of a CD with a guest molecule. The aim of the present study was to investigate the influence of urea on the complexation between dipeptides and ,-CD using Ala-Phe and Ala-Tyr as model compounds. For this purpose three different analytical methods were employed: capillary electrophoresis (CE), 1H-NMR spectroscopy and molecular dynamics simulations (MD). Electropherograms of the peptide enantiomers were different in the presence and absence of urea. For example, at pH,2.5 in the absence of urea the enantiomers of Ala-Tyr are not separated in contrast to the use of buffers containing urea. Applying "complexation-induced chemical shift (CICS)" in NMR spectroscopy and rotating frame Overhauser enhancement spectroscopy (ROESY) revealed differences in the complexation of the peptide enantiomers by ,-CD in the absence and presence of urea suggesting the stabilization of the complex through the phenolic hydroxyl group of tyrosine. MD simulations for different complexes were carried out with consideration of both water and urea molecules in solution. Simulations were performed for 1 ns. In conclusion, NMR spectroscopy and MD methods help to understand the structure of peptide-CD complexes and the separation and migration behavior in CE. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Waveguide Sensors: Use of Reversal Nanoimprinting of Nanoparticles to Prepare Flexible Waveguide Sensors Exhibiting Enhanced Scattering of the Surface Plasmon Resonance (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 11 2010Mater. The image displays a flexible surface plasmon resonance (SPR)-based waveguide sensor prepared by directly imprinting metal nanoparticles onto flexible plates, as presented by H.-L. Chen et al. on page 1742. The metal nanoparticles could scatter the evanescent wave and the guiding mode waves from the SPR-based waveguide simultaneously. The scattering signal underwent a distinguishable red-shift when the target molecules bound to the particles. [source] Silica-Coated Manganese Oxide Nanoparticles as a Platform for Targeted Magnetic Resonance and Fluorescence Imaging of Cancer CellsADVANCED FUNCTIONAL MATERIALS, Issue 11 2010Hong Yang Abstract Monodisperse silica-coated manganese oxide nanoparticles (NPs) with a diameter of ,35,nm are synthesized and are aminated through silanization. The amine-functionalized core,shell NPs enable the covalent conjugation of a fluorescent dye, Rhodamine B isothiocyanate (RBITC), and folate (FA) onto their surface. The formed Mn3O4@SiO2(RBITC),FA core,shell nanocomposites are water-dispersible, stable, and biocompatible when the Mn concentration is below 50,µg mL,1 as confirmed by a cytotoxicity assay. Relaxivity measurements show that the core,shell NPs have a T1 relaxivity (r1) of 0.50,mM,1,s,1 on the 0.5 T scanner and 0.47,mM,1,s,1 on the 3.0 T scanner, suggesting the possibility of using the particles as a T1 contrast agent. Combined flow cytometry, confocal microscopy, and magnetic resonance imaging studies show that the Mn3O4@SiO2(RBITC),FA nanocomposites can specifically target cancer cells overexpressing FA receptors (FARs). Findings from this study suggest that the silica-coated Mn3O4 core,shell NPs could be used as a platform for bimodal imaging (both magnetic resonance and fluorescence) in various biological systems. [source] Use of Reversal Nanoimprinting of Nanoparticles to Prepare Flexible Waveguide Sensors Exhibiting Enhanced Scattering of the Surface Plasmon ResonanceADVANCED FUNCTIONAL MATERIALS, Issue 11 2010Dehui Wan Abstract A flexible surface plasmon resonance (SPR)-based scattering waveguide sensor is prepared by directly imprinting hollow gold nanoparticles (NPs) and solid gold NPs onto flexible polycarbonate (PC) plates,without any surface modification,using a modified reversal nanoimprint lithography technology. Controlling the imprinting conditions, including temperature and pressure, allows for the fine adjustment of the depths of the embedded metal NPs and their SPR properties. This patterning approach exhibits a resolution down to the submicrometer level. A 3D finite-difference time domain simulation is used to examine the optical behavior of light propagating parallel to the air/substrate interface within the near-field regime. Consistent with the simulations, almost an order of magnitude enhancement in the scattering signal after transferring the metal NPs from the glass mold to the PC substrate is obtained experimentally. The enhanced signal is attributed to the particles' strong scattering of the guiding-mode waves (within the waveguide) and the evanescent wave (above the waveguide) simultaneously. Finally, the imprinting conditions are optimized to obtain a strongly scattering bio/chemical waveguide sensor. [source] Genetic influences on human brain structure: A review of brain imaging studies in twins,HUMAN BRAIN MAPPING, Issue 6 2007Jiska S. Peper Abstract Twin studies suggest that variation in human brain volume is genetically influenced. The genes involved in human brain volume variation are still largely unknown, but several candidate genes have been suggested. An overview of structural Magnetic Resonance (brain) Imaging studies in twins is presented, which focuses on the influence of genetic factors on variation in healthy human brain volume. Twin studies have shown that genetic effects varied regionally within the brain, with high heritabilities of frontal lobe volumes (90,95%), moderate estimates in the hippocampus (40,69%), and environmental factors influencing several medial brain areas. High heritability estimates of brain structures were revealed for regional amounts of gray matter (density) in medial frontal cortex, Heschl's gyrus, and postcentral gyrus. In addition, moderate to high heritabilities for densities of Broca's area, anterior cingulate, hippocampus, amygdala, gray matter of the parahippocampal gyrus, and white matter of the superior occipitofrontal fasciculus were reported. The high heritability for (global) brain volumes, including the intracranium, total brain, cerebral gray, and white matter, seems to be present throughout life. Estimates of genetic and environmental influences on age-related changes in brain structure in children and adults await further longitudinal twin-studies. For prefrontal cortex volume, white matter, and hippocampus volumes, a number of candidate genes have been identified, whereas for other brain areas, only a few or even a single candidate gene has been found so far. New techniques such as genome-wide scans may become helpful in the search for genes that are involved in the regulation of human brain volume throughout life. Hum Brain Mapp, 2007. © 2007 Wiley-Liss, Inc. [source] ESR detection of irradiated broad bean (Vicia faba L.) and kinetics of the radiation induced free radical and Mn2+ signalsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2003Mustafa Polat Summary An ESR (Electron Spin Resonance) investigation on irradiated dry broad bean gave a spectrum which was composed of an equally spaced sextet and a single resonance line. These lines appeared at g = 2.0045 (±0.0005) and originated from Mn2+ ions and radiation induced radicals, respectively. Ground broad bean was used throughout the work to avoid any artefacts arising from a microwave cavity filling factor. Free radical signal intensity was observed to increase exponentially in relation to the increase in absorbed dose over the dose range 1.25,15 kGy. Although the Mn2+ signal increases below room temperature, the signal due to the natural and radiation induced radicals decreases. Above room temperature, they both decreased and these decreases were irreversible. The kinetics of these decreases were studied in detail over a temperature range of 308,373 K by annealing samples at different temperatures for various times. [source] Quantum dynamics of a discontinuously kicked charged particle in harmonic, symmetric double, or triple wellsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 6 2009S. Ghosh Abstract The quantum dynamics of a charged particle in a harmonic trap in the presence of discontinuous reversals of a homogeneous or an inhomogeneous electric field is studied. The dynamics reveals classically expected patterns in harmonic wells. In a symmetric double-well potential, the discontinuously switched low intensity homogeneous electric field does not appear to assist tunneling, whereas an inhomogeneous electric field is found to assist the process. Resonance like enhancement is noticed at a critical reversal frequency. Dynamics in a triple well is also analyzed under similar conditions. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Anarchical Governance: Neoliberal Governmentality in Resonance with the State of ExceptionINTERNATIONAL POLITICAL SOCIOLOGY, Issue 4 2009Hiroyuki Tosa Beside the promotion of a politics of inclusion, implemented by governing at a distance, the global governmentality also promotes a politics of exclusion, such as establishing targeted governance that is aimed at deviant groups at the periphery of global politics. This highly disciplinary social control that is imposed upon the marginalized population sometimes leads to instances of the state of exception, in which people are forced to endure "bare lives." This kind of exception existing at the marginalized periphery of the neoliberal global governmentality becomes normal. This neoliberal governmentality creates an informal sector of an enormous scale, whose spatial representation is the global slum, and where vicious cycles of violence become normal. [source] Critical appraisal of rigour in interpretive phenomenological nursing researchJOURNAL OF ADVANCED NURSING, Issue 2 2006Lorna De Witt BScN RN Aim., This paper reports a critical review of published nursing research for expressions of rigour in interpretive phenomenology, and a new framework of rigour specific to this methodology is proposed. Background., The rigour of interpretive phenomenology is an important nursing research methods issue that has direct implications for the legitimacy of nursing science. The use of a generic set of qualitative criteria of rigour for interpretive phenomenological studies is problematic because it is philosophically inconsistent with the methodology and creates obstacles to full expression of rigour in such studies. Methods., A critical review was conducted of the published theoretical interpretive phenomenological nursing literature from 1994 to 2004 and the expressions of rigour in this literature identified. We used three sources to inform the derivation of a proposed framework of expressions of rigour for interpretive phenomenology: the phenomenological scholar van Manen, the theoretical interpretive phenomenological nursing literature, and Madison's criteria of rigour for hermeneutic phenomenology. Findings., The nursing literature reveals a broad range of criteria for judging the rigour of interpretive phenomenological research. The proposed framework for evaluating rigour in this kind of research contains the following five expressions: balanced integration, openness, concreteness, resonance, and actualization. Balanced integration refers to the intertwining of philosophical concepts in the study methods and findings and a balance between the voices of study participants and the philosophical explanation. Openness is related to a systematic, explicit process of accounting for the multiple decisions made throughout the study process. Concreteness relates to usefulness for practice of study findings. Resonance encompasses the experiential or felt effect of reading study findings upon the reader. Finally, actualization refers to the future realization of the resonance of study findings. Conclusion., Adoption of this or similar frameworks of expressions of rigour could help to preserve the integrity and legitimacy of interpretive phenomenological nursing research. [source] Synthesis, cure kinetics, and thermal properties of the Bis(3-allyl-2-cyanatophenyl)sulphoxide/BMI blendsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008G. Anuradha Abstract A novel allyl functionalized dicyanate ester resin bearing sulfoxide linkage was synthesized. The monomer was characterized by Fourier Transform Infrared (FT-IR) Spectroscopy, 1H-, and 13C Nuclear Magnetic Resonance (NMR) spectroscopy and elemental analysis. The monomer was blended with bismaleimide (BMI) at various ratios in the absence of catalyst. The cure kinetics of one of the blends was studied using differential scanning calorimetry [nonisothermal] and the kinetic parameters like activation energy (E), pre-exponential factor (A), and the order of the reaction (n) were calculated by Coats-Redfern method and compared with those calculated using the experimental Borchardt-Daniels method. The thermal stability of the cured dicyanate, BMI, and the blends was studied using thermogravimetric analyzer. The initial weight loss temperature of dicyanate ester is above 380°C with char yield of about 54% at 800°C. Thermal degradation of BMI starts above 463°C with the char yield of about 68%. Inclusion of BMI in cyanate ester increases the thermal stability from 419 to 441°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Highly Ordered Interstitial Water Observed in Bone by Nuclear Magnetic Resonance,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2005Erin E Wilson Abstract NMR was used to study the nanostructure of bone tissue. Distance measurements show that the first water layer at the surface of the mineral in cortical bone is structured. This water may serve to couple the mineral to the organic matrix and may play a role in deformation. Introduction: The unique mechanical characteristics of bone tissue have not yet been satisfactorily connected to the exact molecular architecture of this complex composite material. Recently developed solid-state nuclear magnetic resonance (NMR) techniques are applied here to the mineral component to provide new structural distance constraints at the subnanometer scale. Materials and Methods: NMR dipolar couplings between structural protons (OH, and H2O) and phosphorus (PO4) or carbon (CO3) were measured using the 2D Lee-Goldburg Cross-Polarization under Magic-Angle Spinning (2D LG-CPMAS) pulse sequence, which simultaneously suppresses the much stronger proton-proton dipolar interactions. The NMR dipolar couplings measured provide accurate distances between atoms, e.g., OH and PO4 in apatites. Excised and powdered femoral cortical bone was used for these experiments. Synthetic carbonate (,2-4 wt%)-substituted hydroxyapatite was also studied for structural comparison. Results: In synthetic apatite, the hydroxide ions are strongly hydrogen bonded to adjacent carbonate or phosphate ions, with hydrogen bond (O-H) distances of ,1.96 Å observed. The bone tissue sample, in contrast, shows little evidence of ordered hydroxide. Instead, a very ordered (structural) layer of water molecules is identified, which hydrates the small bioapatite crystallites through very close arrangements. Water protons are ,2.3-2.55 Å from surface phosphorus atoms. Conclusions: In synthetic carbonated apatite, strong hydrogen bonds were observed between the hydroxide ions and structural phosphate and carbonate units in the apatite crystal lattice. These hydrogen bonding interactions may contribute to the long-range stability of this mineral structure. The biological apatite in cortical bone tissue shows evidence of hydrogen bonding with an ordered surface water layer at the faces of the mineral particles. This structural water layer has been inferred, but direct spectroscopic evidence of this interstitial water is given here. An ordered structural water layer sandwiched between the mineral and the organic collagen fibers may affect the biomechanical properties of this complex composite material. [source] Free Radicals in Wheat Seeds Studied by Electron Spin ResonanceJOURNAL OF FOOD SCIENCE, Issue 6 2002F. Szöcs ABSTRACT: We used electron spin resonance (ESR) to investigate free radicals in wheat seeds in air or under vacuum in relation to annealing temperature. Annealing in the 100 to 200 °C range resulted in concentration increases of free radicals in samples. A greater increase was observed for experiments carried out in air than for those under vacuum. Most free radicals occurred in the grain surface layer. The bran contained a concentration of free radicals 100 times greater than that of the white grain portion. The reaction of stable free radicals in bran was also studied during thermal decomposition of dibenzoyl peroxide at high pressure. They reacted with shortlived peroxyl radicals in bran to produce a nonradical product. [source] Cardiac Magnetic Resonance (CMR) Imaging: A Noninvasive Tool for Functional and Morphological Assessment of Coronary Artery Disease:JOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 6 2003Current Clinical Applications, Potential Future Concepts (J Interven Cardiol 2003;16:457,463) [source] Magnetic resonance techniques for the in vivo assessment of multiple sclerosis pathology: Consensus report of the white matter study groupJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2005Massimo Filippi MD Abstract On October 9,11, 2003, the third meeting of the White Matter Study Group of the International Society for Magnetic Resonance in Medicine was held in Venice, Italy. This article is the report of the meeting on how to use MRI in the diagnostic workup of multiple sclerosis (MS) and allied white matter disorders, and to define the nature and the extent of MS pathology in vivo. Both of these steps are central to the design of future treatment strategies aimed at limiting the functional consequences of the most disabling aspects of this disease. J. Magn. Reson. Imaging 2005;21:669,675. © 2005 Wiley-Liss, Inc. [source] Role of magnetic resonance imaging in the diagnosis and monitoring of multiple sclerosis: Consensus report of the White Matter Study Group,JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2002M. Filippi MD Abstract On June 24,26, 2001, the first meeting of the White Matter Study Group (WMSG) of the International Society for Magnetic Resonance in Medicine (ISMRM) was held in Bordeaux, France. This paper is the report of the consensus reached among the delegates of the meeting on how to use magnetic resonance imaging (MRI) to make an early diagnosis of multiple sclerosis (MS), to measure MS activity accurately and reliably, and to monitor the effect of treatment on disease evolution. J. Magn. Reson. Imaging 2002;15:499,504. Published 2002 Wiley-Liss, Inc. [source] Peculiarities of Pyroelectric Resonance,Antiresonance Phenomena in PZT CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2008Svetlana Bravina The pyroelectric characteristics of lead,zirconate,titanate (PZT) ceramics of composition near the morphotropic phase boundary were studied by the photothermomodulation method. The frequency spectra of the amplitude and phase of pyroelectric response in the current and voltage modes were transformed into thermowave profiles. The asymmetry of thickness profiles of the pyroactivity distribution and its reversal under reversing poling voltage polarity were revealed. Attention has been concentrated on elucidation of the peculiarities of pyroelectric resonance,antiresonance (PyRAR) and inverse antiresonance,resonance (PyARR) sequences observed in the 25,35 kHz range thermowave excitation of flexural mode thermomechanical vibrations induced by periodical thermal stresses in the undersurface layer of PZT disks. External voltage-controllable reversible inversion of the sequence PyRAR to PyARR under IR-beam probing of the opposite disk sides, being at different polarities of poling voltage, was found. The connection between poling voltage polarity, the shape of the thermowave profile of pyroelectric parameters, and the inversion of Py (RAR,ARR) sequence were ascertained. The results are compared with those observed earlier for edge-fixed PVDF and P(VDF/TrFE) copolymer films and discussed in regard to highly sensitive pyroelectric detectors. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||