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Intensity Measurements (intensity + measurement)
Selected AbstractsGUSTATORY REACTION TIME AND TIME INTENSITY MEASUREMENTS OF TREHALOSE AND SUCROSE SOLUTIONS AND THEIR MIXTURESJOURNAL OF SENSORY STUDIES, Issue 2 2009MARA VIRGINIA GALMARINI ABSTRACT Dynamic sweetness perception of commercial food grade trehalose, sucrose solutions and their mixtures were studied for a wide range of concentrations. For gustatory reaction time (GRT), concentrations ranged from 2.3 to 13.8% for sucrose and up to 23.0% for trehalose. For time intensity (T-I) sucrose or trehalose solutions (concentration range 2.3,36.8%) and their combinations (23.0 and 36.8% total solids) were analyzed. Trehalose had bigger GRT along the studied range. Both sugars presented similar values for persistence and times of plateau and to maximum intensity, while a significant difference was observed in intensity and GRT at equal concentrations. Trehalose had longer persistence than sucrose in equi -sweet solutions. Overall sweetness profile of some sucrose solutions (i.e., 29.9% sucrose solution and 0.6 sucrose/trehalose ratio mixture at 36.8% total solids) were perceived as similar to mixtures of sucrose/trehalose or single trehalose solutions, which suggests the possibility of sugar replacement without completely modifying sweetness perception. PRACTICAL APPLICATIONS It has been suggested that trehalose may be a potential substitute for sucrose and other sugars used in food formulation because, although its chemical structure is very similar to that of sucrose, it is more stable at low pH and high temperatures. It is not involved in caramelization and does not participate in Maillard reaction with amino acids/proteins. In order to fully establish the potential of trehalose as a functional replacement of sucrose we have determined the sweetness dynamic profile (gustatory reaction time and time-intensity curves) of trehalose solutions and sucrose/trehalose solutions; this aspect is needed for adequately replacing (partially or totally) sucrose in food systems. [source] Humic acid,cetyltrimethylammonium bromide interaction: a fluorimetric studyLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 2 2009Deepa Subbiah Abstract Synchronous and excitation emission matrix fluorescence (EEMF) characteristics of humic acid,surfactant interaction have been studied. The variation of synchronous and EEMF spectral maxima and intensities with humic acid (HA),cetyltrimethylammonium bromide (CTAB) composition sensitively reflects the extent of flocculation of HA. It was found that the concentration range for co-precipitation of HA,CTAB was similar for all concentrations (60 p.p.m., 80 p.p.m. and 100 p.p.m.) of humic acid studied. In the concentration range 60,150 p.p.m. of humic acid, the EEMF maximum is found at 460/540 nm, indicating the presence of ligneous materials. Fluorescence intensity measurement at this contour excitation/emission wavelength (460/540 nm) is suggested as a convenient and a sensitive method for studying the physical state of humic acid in the presence of cationic surfactants. No significant interaction of HA with sodium dodecylsulphate (SDS) and TX-100 was found. Copyright © 2008 John Wiley & Sons, Ltd. [source] The use of X-ray crystallography to determine absolute configurationCHIRALITY, Issue 5 2008H. D. Flack Abstract Essential background on the determination of absolute configuration by way of single-crystal X-ray diffraction (XRD) is presented. The use and limitations of an internal chiral reference are described. The physical model underlying the Flack parameter is explained. Absolute structure and absolute configuration are defined and their similarities and differences are highlighted. The necessary conditions on the Flack parameter for satisfactory absolute-structure determination are detailed. The symmetry and purity conditions for absolute-configuration determination are discussed. The physical basis of resonant scattering is briefly presented and the insights obtained from a complete derivation of a Bijvoet intensity ratio by way of the mean-square Friedel difference are exposed. The requirements on least-squares refinement are emphasized. The topics of right-handed axes, XRD intensity measurement, software, crystal-structure evaluation, errors in crystal structures, and compatibility of data in their relation to absolute-configuration determination are described. Characterization of the compounds and crystals by the physicochemical measurement of optical rotation, CD spectra, and enantioselective chromatography are presented. Some simple and some complex examples of absolute-configuration determination using combined XRD and CD measurements, using XRD and enantioselective chromatography, and in multiply-twinned crystals clarify the technique. The review concludes with comments on absolute-configuration determination from light-atom structures. Chirality, 2008. © 2007 Wiley-Liss, Inc. [source] A new type of susceptibility-artefact-based magnetic resonance angiography: intra-arterial injection of superparamagnetic iron oxide particles (SPIO) A Resovist® in combination with TrueFisp imaging: a feasibility studyCONTRAST MEDIA & MOLECULAR IMAGING, Issue 5 2006Robbert M. Maes Abstract The goal of this study was to evaluate the use of super paramagnetic particles of iron oxide (SPIO) as a dark blood contrast agent, in combination with a bright blood steady-state free precession sequence for magnetic resonance angiography (MRA), in an animal model. The original concentration of the SPIO of 500,mmol Fe/l and dilutions to 250, 125, 60, 30, 10 and 5,mmol Fe/l were intra-arterially injected into the aorta of a pig. Then the dilution of 10,mmol Fe/l was chosen for repeated intra-arterial injections into two pigs. During these intra-arterial SPIO injections MR images were acquired with a 1.5,T scanner. Signal intensity measurements were performed in the aorta. The signal-to-noise ratio during SPIO bolus passage was significantly less than during baseline conditions (Fisher's F -ratio 159.8, p,<,0.005) or the recovery signal-to-noise ratio (Fisher's F -ratio 144.6, p,<,0.005). Also, confirmation of flow distal to the catheter-tip position was possible. The use of SPIO as a dark blood agent in combination with a bright blood MR imaging sequence is feasible. Temporary loss of intraluminal signal occurs due to local decrease of the signal because of induction of local inhomogeneities after mixture the present blood and SPIO solution. It provides immediate information about blood flow distal to the catheter and is a potentially useful to guide intravascular MR-interventional procedures. Copyright © 2006 John Wiley & Sons Ltd. [source] Microaffinity purification of proteins based on photolytic elution: Toward an efficient microbead affinity chromatography on a chipELECTROPHORESIS, Issue 3 2005Woo-Jae Chung Abstract A bead affinity chromatography system, which was based on the photolytic elution method, was integrated into a glass-silicon microchip to purify specific target proteins. CutiCore® beads, which were coupled with a photo-cleavable ligand, such as biotin and an RNA aptamer, were introduced into a filter chamber in the microchip. The protein mixture containing target protein labeled with fluorescein isothiocyanate (FITC) was then passed through the packed affinity beads in the microchamber by pressure-driven flow. During the process, the adsorbed protein on the bead was monitored by fluorescence. The concentrated target protein on the affinity bead was released by simple irradiation with UV light at a wavelength of 360 nm, and subsequently eluted with the phosphate buffer flow. The eluted target protein was quantitatively detected via the fluorescence intensity measurements at the downstream of the capillary connected to the outlet of the microchip. The microaffinity purification allowed for a successful method for the identification of specific target proteins from a protein mixture. In addition, the feasibility of this system for use as a diagnosis chip was demonstrated. [source] Far-field characterization of small aperturesJOURNAL OF MICROSCOPY, Issue 2 2003N. I. Petrov Summary A far-field method for characterizing apertures based on the relationship between the relative intensity of propagating modes in a given medium and a small aperture illuminated with a light beam is proposed. A simple optical set-up based on computer-generated holograms and spatial filters is suggested to measure the relative strength of modes and provide axial intensity measurements in the far-field zone. It is shown that the minimal size of a spot that may be measured decreases with an increase in the refractive index of a medium into which light propagates and with the use of high-order spatial mode filters. The intensities transmitted through tapered optical fibre tips have been measured and their aperture diameters determined using window-type spatial filters. The results have been compared with measurements using scanning electron microscopy. [source] Biphoton spectroscopy of YAG:Er3+ crystalLASER PHYSICS LETTERS, Issue 10 2007A.A. Kalachev Abstract The absorption spectrum of Er3+ ions in YAG crystal in the range from 645 nm to 655 nm was measured with the resolution of 0.01 nm using the frequency-anticorrelated broadband photon pairs (biphotons) generated by spontaneous parametric down-conversion. The spectrum of the sample was measured by counting the coincidences when the impurity crystal was placed in front of the signal photon detector, whilst the wavelength of the idler photons was resolved by a monochromator which was placed in front of another photon detector. The results are in agreement with those obtained by the usual intensity measurements with a classical light source and a monochromator. It was shown experimentally that the biphoton spectroscopy, unlike the usual single photon spectroscopy, allows one to obtain the spectroscopic information in the presence of an external noise such as background thermal radiation. (© 2007 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Immunohistological intensity measurements as a tool to assess sarcolemma-associated protein expressionNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 4 2010V. Arechavala-Gomeza V. Arechavala-Gomeza, M. Kinali, L. Feng, S. C. Brown, C. Sewry, J. E. Morgan and F. Muntoni (2010) Neuropathology and Applied Neurobiology36, 265,274 Immunohistological intensity measurements as a tool to assess sarcolemma-associated protein expression Aims: The quantification of protein levels in muscle biopsies is of particular relevance in the diagnostic process of neuromuscular diseases, but is difficult to assess in cases of partial protein deficiency, particularly when information on protein localization is required. The combination of immunohistochemistry and Western blotting is often used in these cases, but is not always possible if the sample is scarce. We therefore sought to develop a method to quantify relative levels of sarcolemma-associated proteins using digitally captured images of immunolabelled sections of skeletal muscle. Methods: To validate our relative quantification method, we labelled dystrophin and other sarcolemmal proteins in transverse sections of muscle biopsies taken from Duchenne muscular dystrophy and Becker muscular dystrophy patients, a manifesting carrier of Duchenne muscular dystrophy and normal controls. Results: Using this method to quantify relative sarcolemmal protein abundance, we were able to accurately distinguish between the different patients on the basis of the relative amount of dystrophin present. Conclusions: This comparative method adds value to techniques that are already part of the diagnostic process and can be used with minimal variation of the standardized protocols, without using extra amounts of valuable biopsy samples. Comparative quantification of sarcolemmal proteins on immunostained muscle sections will be of use to establish both the abundance and localization of the protein. Moreover, it can be applied to assess the efficacy of experimental therapies where only partial restoration or upregulation of the protein may occur. [source] Open-circuit voltage increase dynamics in high and low deposition rate polymorphous silicon solar cellsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2010E. V. Johnson Abstract The dynamics of the open-circuit voltage (VOC) of polymorphous silicon (pm-Si:H) solar cells deposited at high and low rates (8 and 1.5,Å/s, HR and LR) and containing lightly or heavily doped p-layers (LD or HD) are compared through in situ, variable intensity measurements during light-soaking (LS). The VOC's of the LR cells show an increase with LS, regardless of doping level, whereas the HR cells show decreasing VOC's. This result is in contrast to the changes predicted by the dark diode characteristics, which predict increasing VOC for all the devices. The device measurements are compared to the analogous measurements on co-deposited coplanar p,i layer stacks to determine whether the VOC dynamics can be linked to changes in the p-layer doping efficiency during LS. The changes to the macroscopic electrical behaviour of the cell under varying light conditions are modelled using a simple, three parameter function, and are compared to results from a detailed, numerical modelling tool, AFORS-HET. [source] Surface activity,thermodynamic properties and light scattering studies for some novel aliphatic polyester surfactantsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 5 2004R. A. El-Ghazawy Abstract The preparation of 12 new polyester surfactants based on aliphatic amines and different ethylene oxide content is described. These surfactants were characterized by determining their molecular weights and polydispersity by gel permeation chromatography (GPC) and nitrogen content. Drop volume tensiometry (DVT) was used to measure the surface tension at 25, 35, 45 and 55°C. The surface tension isotherms were used to determine critical micelle concentration (CMC), maximum Gibb's adsorption (,max), minimum area per molecule (Amin), the effectiveness of surface tension reduction (,cmc) and the efficiency (pC20). The thermodynamic parameters of micellization (,Gmic, ,Hmic, ,Smic) and of adsorption (,Gad, ,Had, ,Sad) were calculated and the data showed that these surfactants favor micellization to adsorption. The static scattered light intensity measurements provide the calculation of the molecular weight of micelle and the aggregation number (N°), while the dynamic light scattering provide the hydrodynamic radius of micelle (RH) and the diffusion coefficient at different surfactant concentrations. The hydrodynamic radius of micelle (RH) at different surfactant concentrations could be used also to determine the CMC giving results that are comparable to those obtained by surface tension measurements. All the data are discussed regarding the chemical structure of the polymeric surfactants. Copyright © 2004 John Wiley & Sons, Ltd. [source] Enhancing MAD FA data for substructure determinationACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2010Hongliang Xu Heavy-atom substructure determination is a critical step in phasing an unknown macromolecular structure. Dual-space (Shake-and-Bake) recycling is a very effective procedure for locating the substructure (heavy) atoms using FA data estimated from multiple-wavelength anomalous diffraction. However, the estimated FA are susceptible to the accumulation of errors in the individual intensity measurements at several wavelengths and from inaccurate estimation of the anomalous atomic scattering corrections f, and f,,. In this paper, a new statistical and computational procedure which merges multiple FA estimates into an averaged data set is used to further improve the quality of the estimated anomalous amplitudes. The results of 18 Se-atom substructure determinations provide convincing evidence in favor of using such a procedure to locate anomalous scatterers. [source] Associations of 25 structural, degradative, and inflammatory candidate genes with lumbar disc desiccation, bulging, and height narrowingARTHRITIS & RHEUMATISM, Issue 2 2009Tapio Videman Objective To examine the allelic diversity of structural, inflammatory, and matrix-modifying gene candidates and their association with disc degeneration. Methods Subjects were 588 men ages 35,70 years. We investigated associations of single-nucleotide polymorphisms in AGC1 and in 12 collagen, 8 interleukin, and 4 matrix metalloproteinase genes with quantitative magnetic resonance imaging measurements of disc desiccation and disc bulging and height narrowing scores, after controlling for age and suspected risk factors. Analyses were performed using QTDT software. P values were derived from 1,000 permutations, and empirical P values for global significance also were applied. Results Twelve of the 99 variants in 25 selected candidate genes provided evidence of association (P < 0.05) with disc signal intensity in the upper and/or lower lumbar regions. Allelic variants of AGC1 (rs1042631; P = 0.001), COL1A1 (rs2075555; P = 0.005), COL9A1 (rs696990; P = 0.00008), and COL11A2 (rs2076311; P = 0.018) genes provided the most significant evidence of association with disc signal intensity. The same variants of AGC1 (P = 0.010) and COL9A1 (P = 0.014), as well as variants in the COL11A1 gene (rs1463035 [P = 0.004]; rs1337185 [P = 0.015]) were also associated with disc bulging, as was AGC1 with disc height narrowing (rs1516797; P = 0.005). In addition, 4 allelic variants in the immunologic candidate genes (rs2071375 in IL1A [P = 0.027]; rs1420100 in IL18RAP [P = 0.005]) were associated with disc signal intensity. Conclusion Genetic variants account for interindividual differences in disc matrix synthesis and degradation. The accuracy of the quantitative disc signal intensity measurements we used likely enhanced our ability to observe these associations. Our findings shed light on possible mechanisms of degeneration and support the view that disc degeneration is a polygenetic condition. [source] Modulation of protein kinase C by curcumin; inhibition and activation switched by calcium ionsBRITISH JOURNAL OF PHARMACOLOGY, Issue 2 2007Y A Mahmmoud Background and purpose: Previous studies have identified the natural polyphenol curcumin as a protein kinase C (PKC) inhibitor. In contrast, we found significant stimulation of PKC activity following curcumin treatment. Thus, the mechanism of curcumin interaction with PKC was investigated. Experimental approach: We employed phosphorylation assays in the presence of soluble or membrane-bound PKC substrates, followed by SDS,PAGE, autoradiography and phosphorylation intensity measurements. Key results: Curcumin inhibited PKC in the absence of membranes whereas stimulation was observed in the presence of membranes. Further analysis indicated that curcumin decreased PKC activity by competition with Ca2+ stimulation of the kinase, resulting in inhibition of activity at lower Ca2+ concentrations and stimulation at higher Ca2+ concentrations. The role of the membrane is likely to be facilitation of Ca2+ -binding to the kinase, thus relieving the curcumin inhibition observed at limited Ca2+ concentrations. Curcumin was found to mildly stimulate the catalytic subunit of PKC, which does not require Ca2+ for activation. In addition, studies on Ca2+ -independent PKC isoforms as well as another curcumin target (the sarcoplasmic reticulum Ca2+ -ATPase) confirmed a correlation between Ca2+ concentration and the curcumin effects. Conclusions and Implications: Curcumin competes with Ca2+ for the regulatory domain of PKC, resulting in a Ca2+ -dependent dual effect on the kinase. We propose that curcumin interacts with the Ca2+ -binding domains in target proteins. To our knowledge, this is the first study that defines an interaction domain for curcumin, and provides a rationale for the broad specificity of this polyphenol as a chemopreventive drug. British Journal of Pharmacology (2007) 150, 200,208. doi:10.1038/sj.bjp.0706970 [source] Hydrogen Adsorption and Diffusion in p - tert -Butylcalix[4]arene: An Experimental and Molecular Simulation StudyCHEMISTRY - A EUROPEAN JOURNAL, Issue 38 2010Dr. Saman Alavi Abstract Experimental adsorption isotherms were measured and computer simulations were performed to determine the nature of the H2 gas uptake in the low-density p - tert -butylcalix[4]arene (tBC) phase. 1H,NMR peak intensity measurements for pressures up to 175,bar were used to determine the H2 adsorption isotherm. Weak surface adsorption (up to ,2,mass,% H2) and stronger adsorption (not exceeding 0.25,mass,% or one H2 per calixarene bowl) inside the calixarene phase were detected. The latter type of adsorbed H2 molecule has restricted motion and shows a reversible gas adsorption/desorption cycle. Pulsed field gradient (PFG) NMR pressurization/depressurization measurements were performed to study the diffusion of H2 in the calixarene phases. Direct adsorption isotherms by exposure of the calixarene phase to pressures of H2 gas to ,60,bar are also presented, and show a maximum H2 adsorption of 0.4,H2 per calixarene bowl. Adsorption isotherms of H2 in bulk tBC have been simulated using grand canonical Monte Carlo calculations in a rigid tBC framework, and yield adsorptions of ,1,H2 per calixarene bowl at saturation. Classical molecular dynamics simulations with a fully flexible calixarene molecular force field are used to determine the guest distribution and inclusion energy of the H2 in the solid with different loadings. [source] | ||||||||||||||||