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Polarization Technique (polarization + technique)
Selected AbstractsOrthogonal polarization technique in the assessment of human skin microcirculationINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 5 2008Omar Lupi MD Background The "gold standard" for the study of the in vivo microcirculation is intravital microscopy. The recently developed method of orthogonal polarization of light [orthogonal polarization spectral (OPS) imaging] allows for the in vivo transcutaneous evaluation of the microcirculation without the need for invasive surgical procedures. Methods The application of polarized light originating from a 100 W halogen tungsten lamp is able to penetrate tissues at a depth of up to 3 mm, and generates reissued light from this depth. The evaluation of this depolarized light, from a deeper origin, may be carried out separately from the light reflected by the more superficial layers of the tissue under study because this light retains photon polarization, whereas the former light undergoes real depolarization. Results The process of validation of the OPS technique, when compared with intravital microscopy, the "gold standard" for the in vivo observation of the microcirculation, has shown that it is as effective and reliable as the gold standard, reaching the same resolution level in the visualization of blood vessels, but without the need for invasive surgical procedures. Conclusions The OPS technique is a very promising tool for dermatologists and researchers, especially in the study of vasculitis, chronic venous insufficiency, and skin tumors. [source] Poly(O -anisidine) coatings electrodeposited onto AL-2024: Synthesis, characterization, and corrosion protection evaluationADVANCES IN POLYMER TECHNOLOGY, Issue 4 2004Kunal Shah Abstract Poly(O -anisidine) coating was successfully electrodeposited onto Al-2024. Cyclic voltammetry and reflection absorption infrared spectroscopy (RAIR) analysis were carried out in order to fully understand the formation and structure of the resulting polymer coating. RAIR spectrum showed the characteristics peaks of poly(O -anisidine). As the reaction time was varied, the CV peak shifted from 0.75 to 0.81 V vs. SCE suggesting that a change in structure of the polymer from a reduced state to a partially oxidized form has occurred. UV spectrum showed two peaks at 320 and 620 nm suggesting the presence of conjugation on the polymer backbone. The deposition of the poly(O -anisidine) onto the substrate was controlled by nucleation and growth mechanism. DC polarization technique was used to evaluate the corrosion protection offered by poly(O -anisidine) coatings. Preliminarily data shows that these coatings help to ennoble the surface of the substrate. © 2004 Wiley Periodicals, Inc. Adv Polym Techn 23: 291,297, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20024 [source] Comparison of the corrosion protection of mild steel by polypyrrole,phosphate and polypyrrole,tungstenate coatingsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008M. G. Hosseini Abstract The electrodeposition of polypyrrole,phosphate (PPy,P) and polypyrrole,tungstenate (PPy,W) on mild steel (MS) were achieved in an oxalic acid medium with cyclic voltammetry techniques. Adherent and homogeneous PPy,P and PPy,W films were obtained. The corrosion behavior of mild steel with phosphate (PPy,P) and tungstenate (PPy,W) composite coatings in 3.5% NaCl solutions were investigated through a potentiodynamic polarization technique, open-circuit potential,time curves, and electrochemical impedance spectroscopy (EIS). On the basis of a physical model for corrosion of mild steel composites, Zview (II) software was applied to the EIS to estimate the parameters of the proposed equivalent circuit. It was found that the PPy,W coatings could provide much better protection than the PPy,P and polypyrrole coatings. The effects of the phosphate and tungstenate process parameters on the morphology and structure of the passive films were investigated by scanning electron microscopy and electron dispersion X-ray analyses. The results reveal that the PPy,P and PPy,W coated electrodes offered a noticeable enhancement in protection against corrosion processes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Field-free molecular alignment of CO2 mixtures in presence of collisional relaxationJOURNAL OF RAMAN SPECTROSCOPY, Issue 6 2008T. Vieillard Abstract The present work explores the extension of the concept of short-pulse-induced alignment to dissipative environments within quantum mechanical density matrix formalism (Liouville equation) from the weak to the strong field regime. This is illustrated within the example of the CO2 molecule in mixture with Ar and He, at room temperature, for which a steep decrease of the alignment is observed at moderate pressure because of the collisional relaxation. The field-free alignment is measured by a polarization technique where the degree of alignment is monitored in the time domain by measuring the resulting transient birefringence with a probe pulse Raman induced polarization spectroscopy (RIPS) Copyright © 2008 John Wiley & Sons, Ltd. [source] Parahydrogen-induced polarization in imaging: Subsecond 13C angiographyMAGNETIC RESONANCE IN MEDICINE, Issue 1 2001K. Golman Abstract High nuclear spin polarization of 13C was reached in organic molecules. Enhancements of up to 104, compared to thermal polarization at 1.5 T, were achieved using the parahydrogen-induced polarization technique in combination with a field cycling method. While parahydrogen has no net polarization, it has a high spin order, which is retained when hydrogen is incorporated into another molecule by a chemical reaction. By subjecting this molecule to a sudden change of the external magnetic field, the spin order is transferred into net polarization. A 13C angiogram of an animal was generated in less than a second. Magn Reson Med 46:1,5, 2001. © 2001 Wiley-Liss, Inc. [source] Testing procedure to obtain reliable potentiodynamic polarization curves on type 310S stainless steel in alkali carbonate meltsMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 4 2006S. Frangini Abstract Potentiodynamic polarization measurements have been employed to evaluate the anodic behavior of a type 310S stainless steel in the eutectic Li/K molten carbonate. In general, the electrochemical tests yield useful information to predict the stability of the oxide films formed on the surface at the initial period of corrosion, although some precaution is required in the testing procedure as the reproducibility of results is seen to be adversely affected by the passage of large currents. Especially when the steel is in a passive state, erratic results are easily observed if the corrosion layer is being damaged by uncontrolled large currents. This is because the acid-base properties of the melt are susceptible to deep changes by applied currents in the milli-ampere range resulting in hysteresis phenomena in the polarization plot. Hysteresis is caused, on one hand, by acidic dissolution of the passive layer at high anodic currents and, on the other hand, by increased melt basicity due to oxide ion build-up at high cathodic currents. An optimized testing procedure is therefore suggested that minimizes these effects by imposing a 2 mA/cm2 threshold current during polarization measurements. Moreover, the conditions for the applicability of the linear polarization technique to estimate kinetic parameters have been discussed in relationship with the corrosion mechanisms analysed by impedance spectra. It is concluded that the presence of diffusional impedance terms and formation of surface resistive films in molten carbonates may result in not reliable polarization resistance values obtained with the linear polarization. [source] | ||||||||||||||||