Home About us Contact
|
Home About us Contact | ||
|
|
||
Experimental Aspects (experimental + aspect)
Selected AbstractsClinical and Experimental Aspects of Olmesartan Medoxomil, a New Angiotensin II Receptor AntagonistCARDIOVASCULAR THERAPEUTICS, Issue 4 2004Kazunori Yoshida ABSTRACT Olmesartan medoxomil is a new orally active angiotensin II (Ang II) type 1 receptor antagonist. It is a prodrug and is rapidly de-esterified during absorption to form olmesartan, the active metabolite. Olmesartan is a potent, competitive and selective Ang II type 1 receptor antagonist. Olmesartan is not metabolized by the cytochrome P-450 and has a dual route of elimination, by kidneys and liver. In patients with essential hypertension olmesartan medoxomil administered once daily at doses of 10,80 mg dose-dependently reduced diastolic blood pressure (DBP). Troughto-peak ratios for both DBP and systolic blood pressure (SBP) were above 50%. At the recommended once-daily starting doses, olmesartan medoxomil (20 mg) was more effective than losartan (50 mg), valsartan (80 mg) or irbesartan (150 mg) in reducing cuff DBP in patients with essential hypertension. The results of cuff SBP and mean 24-h DBP and SBP were similar to those of cuff DBP measurement. In mild-to-moderate hypertensive patients the recommended starting dose of olmesartan medoxomil was as effective as that of amlodipine besylate (5 mg/day) in reducing both cuff and 24-h blood pressure. In lowering DBP olmesartan medoxomil, at 10,20 mg/day, was as effective as atenolol at 50,100 mg/day. In mild-to-moderate hypertensive patients, olmesartan medoxomil, at 5,20 mg once daily, was more effective than captopril at 12.5,50 mg twice daily. At 20,40 mg once daily olmesartan medoxomil was as effective as felodipine, at 5,10 mg once daily. Olmesartan medoxomil has minimal adverse effects with no clinically important drug interactions. Animal studies have shown that olmesartan medoxomil provides a wide range of organ protection. Olmesartan medoxomil ameliorated atherosclerosis in hyperlipidemic animals and ameliorated cardiac remodeling and improved survival in rats with myocardial infarction. Olmesartan medoxomil has renoprotective effects in a remnant kidney model and type 2 diabetes models. Future investigation should reveal whether these beneficial effects of olmesartan medoxomil are applicable to human diseases. [source] Determination of dissociation constants of folic acid, methotrexate, and other photolabile pteridines by pressure-assisted capillary electrophoresisELECTROPHORESIS, Issue 17 2006Zoltán Szakács Abstract Pressure-assisted CE (PACE) was applied to determine the previously inaccessible complete set of pK values for folic acid and eight related multiprotic compounds. PACE allowed the determination of all acidity macroconstants at low (,0.1,mM) concentration without interferences of selfassociation or photodegradation throughout the pH range. The accuracy of the constants was verified by NMR-pH, UV-pH, and potentiometric titrations and the data could be converted into physiological ionic strength. It was shown that even three overlapping pK values can be determined by CE with good precision (<0.06) and accuracy if an appropriately low sample throughput is used. Experimental aspects of PACE for the quantitation of acid,base properties are analyzed. The site-specific basicity data obtained for folic acid and methotrexate (MTX) reveal that apparently slight constitutional differences between folic acid and MTX carry highly different proton-binding propensities at analogous moieties, especially at the pteridine N1,locus, providing straightforward explanation for the distinctive binding to dihydrofolate reductase at the molecular level. [source] Experimental aspects of solid state circular dichroism,CHIRALITY, Issue 1E 2009Ettore Castiglioni Abstract The interest of circular dichroism in the solid state is stimulated by several needs, such as the desire to get solvent free spectra, the insolubility of the sample or the intrinsic process in which the sample itself is prepared or manipulated. We approach the argument on the basis of the sampling technique, since each different case calls for specific care in getting proper results. Chirality 21:E28,E36, 2009. © 2009 Wiley-Liss, Inc. [source] Effect of temperature on water retention phenomena in deformable soils: theoretical and experimental aspectsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 1 2010S. Salager In this paper, a theoretical and experimental investigation of the effect of temperature on water retention phenomena in deformable soils is presented. A general law expressing the change in suction with water content, temperature and void ratio is proposed theoretically. This law accounts for the influence of density and temperature on water retention. It also provides a general framework which appears to be well-adapted to describe many particular cases. The effect of temperature is studied through a predictive relationship which is established in this framework. This relationship allows us to obtain the water retention curve at any temperature from that at a reference temperature, thus reducing strongly the number of tests required to characterize the thermo-hydraulic behaviour of a soil. The relevance of this relationship was experimentally verified from new tests as well as the results previously reported in the literature. The new tests were performed on two model media, namely, a terracotta ceramic and a clayey-silty sand. The tests taken from the literature concerned two different clays. Comparison between theoretical prediction and experimental data was particularly promising and shows the capability of the model to cover a wide range of soils. [source] From lumped-element circuits to monolithic integrated circuits: A contribution to RF and microwave mixer designINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 4 2005Peter Waldow Abstract This article deals with the mixer design for UHF-, microwave- and millimeter-wave applications. Thereby, several aspects such as the chosen technology (lumped elements, hybrid- or monolithic integration) and the applied transmission line (printed circuits, strip-, slot- or coplanar line) are considered. During the course of this contribution, the authors point out the developments in mixer design from lumped-element circuits to monolithic integrated circuits on the example of research activities in Duisburg and Kamp-Lintfort, Germany. The results of these scientific investigations, regarding both the theoretical and experimental aspects, show the feasibility of the proposed techniques. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005. [source] A method for the non-destructive analysis of gradients of mechanical stresses by X-ray diffraction measurements at fixed penetration/information depthsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2006A. Kumar A rigorous measurement strategy for (X-ray) diffraction stress measurements at fixed penetration/information depths has been developed. Thereby errors caused by lack of penetration-depth control in traditional (X-ray) diffraction (sin2,) measurements have been annulled. The range of accessible penetration/information depths and experimental aspects have been discussed. As a practical example, the depth gradient of the state of residual stress in a sputter-deposited nickel layer of 2,µm thickness has been investigated by diffraction stress measurements with uncontrolled penetration/information depth and two controlled penetration/information depths corresponding to about one quarter and one tenth of the layer thickness, respectively. The decrease of the planar tensile stress in the direction towards the surface could be well established quantitatively. [source] 31P NMR spectroscopy in the quality control and authentication of extra-virgin olive oil: A review of recent progressMAGNETIC RESONANCE IN CHEMISTRY, Issue 5 2007Photis Dais Abstract This review is a brief account on the application of a novel methodology to the quality control and authentication of extra-virgin olive oil. This methodology is based on the derivatization of the labile hydrogens of functional groups, such as hydroxyl and carboxyl groups, of olive oil constituents with the phosphorus reagent 2-chloro-4,4,5,5-tetramethyldioxaphospholane, and the use of the 31P chemical shifts to identify the phosphitylated compounds. Various experimental aspects such as pertinent instrumentation, sample preparation, acquisition parameters and properties of the phosphorus reagent are reviewed. The strategy to assign the 31P signals of the phosphitylated model compounds and olive oil constituents by employing 1D and 2D NMR experiments is presented. Finally, the capability of this technique to assess the quality and the genuineness of extra-virgin olive oil and to detect fraud is discussed. Copyright © 2007 John Wiley & Sons, Ltd. [source] Clinical and experimental aspects of Adreno-muscarinic synergy in the bladder base and prostate,,NEUROUROLOGY AND URODYNAMICS, Issue 8 2009Alexander Roosen Abstract Recent clinical trials have shown that combination therapy using an alpha-receptor antagonist and an antimuscarinic is more effective than either agent alone in improving quality of life and objective urodynamic variables in men with bladder outflow obstruction. There appear to be no negative effects on bladder function. The mode of action of this combination is unknown but presumed to be an antimuscarinic reduction in detrusor overactivity and the alpha-receptor antagonist reduced outflow tract resistance. We have shown with in vitro experiments that in smooth muscles influencing outflow tract resistance (prostate, trigone) there is a profound contractile synergy between adrenergic and muscarinic pathways. We propose the hypothesis that both arms of the combination therapy reduce contractile tone of the outflow tract and that their simultaneous attenuation has a disproportionately large effect on outflow tract resistance. Our data from trigone muscle suggest that adrenergic and muscarinic receptor activation increase the intracellular [Ca2+] but the adrenergic pathway also operates through Ca2+ -sensitisation of the contractile apparatus, primarily through a PKC-dependent pathway. Neurourol. Urodynam. 28:938,943, 2009. © 2009 Wiley-Liss, Inc. [source] Co2MnSi as full Heusler alloy ferromagnetic electrode in magnetic tunneling junctionsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2006G. Reiss Abstract The discoveries of antiferromagnetic coupling in Fe/Cr multilayers by Grünberg, the Giant MagnetoResistance by Fert and Grünberg and a large tunneling magnetoresistance at room temperature by Moodera have triggered enormous research on magnetic thin films and magnetoelectronic devices. Large opportunities are especially opened by the spin dependent tunneling resistance, where a strong dependence of the tunneling current on an external magnetic field can be found. In order to obtain large magnetoresistance effects, materials with strongly spin polarized electron gas around the Fermi level have to be found. New materials with potentially 100% spin polarization will be discussed using the example of the full Heusler compound Co2MnSi. First, experimental aspects of the integration of this alloy in magnetic tunneling junctions will be addressed. With these junctions, we obtain up to 100% TMR at low temperature. The current status of this research will then be summarized with special regard to the complex diffusion mechanisms occurring in these devices and to the properties of the interfaces between the Heusler material and the insulator. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Specific interactions in ternary system quaternized polysulfone/mixed solventPOLYMER ENGINEERING & SCIENCE, Issue 1 2009Anca Filimon Theoretical and experimental aspects on the specific interactions developed via electrostatic interactions and hydrogen-bonding in a ternary system formed of a proton-donor solvent (N,N -dimethylformamide or methanol), a proton-acceptor solvent (water), and a quaternized polysulfone with various contents of ionic chlorine, which indicates a proton-acceptor character, are investigated. Thus, the interactions of the ternary systems are corrected on the basis of the association phenomena defined through association constants. Numerical values for these constants were evaluated as a function of the system composition, by mathematical simulations for an accurate adjustment of preferential adsorption, determined by the Flory,Huggins,Pouchly theoretical approach applied to the experimental data. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers [source] Reactive compatibilization of nylon copolymer/EPDM blends: experimental aspects and their comparison with theoryPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 5 2008Cibi Komalan Abstract In situ reactive compatibilization was first time applied to a low melting nylon (nylon 6 and 66 copolymer) and EPDM blend system. The effects of in situ compatibilization and concentration of compatibilizer on the morphology and mechanical properties of nylon/EPDM blends have been investigated. The influence of EPM-g-MA on the phase morphology was examined by the scanning electron microscopy (SEM) after preferential extraction of the minor phase. The SEM micrographs were quantitatively analyzed for domain size measurements. The compatibilizer concentrations used were 0, 1, 2.5, 5, and 10,wt%. The graft copolymer (nylon-g-EPM) formed at the interface showed relatively high emulsifying activity. A maximum phase size reduction was observed when 2.5,wt% of compatibilizer was added to the blend system. This was followed by a leveling-off at higher loadings indicating interfacial saturation. The conformation of the compatibilizer at the interface was deduced based on the area occupied by the compatibilizer at the blend interface. The experimental compatibilization results were compared with theoretical predictions of Noolandi and Hong. It was concluded that the molecular state of compatibilizer at interface changes with concentration. The in situ compatibilized blends showed considerable improvement in mechanical properties. Measurement of tensile properties shows increased elongation as well as enhanced modulus and strength up on compatibilization. At higher concentrations of compatibilizer, a leveling-off of the tensile properties was observed. A good correlation has been observed between the mechanical properties and morphological parameters. Copyright © 2007 John Wiley & Sons, Ltd. [source] Chiral determination: direct interpretation of convergent-beam electron diffraction patterns using the series expansion of Cowley and MoodieACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2007Andrew W. S. Johnson Given a small number of structure factors of a known chiral structure of unknown hand, it is shown that the hand can be determined from the sign of the contrast difference of two reflections in a suitably oriented convergent-beam electron diffraction (CBED) pattern. A simple formula for this difference, which takes into account all the significant second-order scattering, is derived using the series expansion of Cowley and Moodie for n -beam diffraction. The reason for the success of a three-beam interpretation is investigated. The method is applied to patterns from thin crystals in which a mirror projection symmetry can be found and its validity is demonstrated by agreement with experiment using samples of known hand. The advantages of recording patterns near major zone axes are discussed as well as some other experimental aspects of chiral determination using CBED. [source] | ||||||||||||||||