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Search Results: 1 - 10 of 1467 matches for " Polarization "
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Economic and Social Impact of Tourism on a Small Town: Peterborough New Hampshire  [PDF]
Tomoko Tsundoda, Samuel Mendlinger
Journal of Service Science and Management (JSSM) , 2009, DOI: 10.4236/jssm.2009.22009
Abstract: This study examined the perceived impacts of tourism on the lives of people from a small New England town. Twenty seven in-depth unstructured interviews were conducted. The study found that most people perceive both positive and negative impacts of tourism and do not want to change their town for increased tourism development even if it results in increased revenue. People recognized tourism’s benefit to the town’s economy but less so to their economic situation. Working locals expressed worry regarding the town’s gradually polarized economy and divided social classes and regard tourism as one of the causes. Wealthier members generally view tourism at its present level as beneficial. For further tourism development Peterborough’ population will need to solve this dilemma.
Inhibition Mechanism of Pitting Corrosion of Nickel in Aqueous Medium by Some Macrocyclic Compounds  [PDF]
Fatma Mohamed Mahgoub, Ahmed Mohamed Hefnawy
Open Journal of Physical Chemistry (OJPC) , 2012, DOI: 10.4236/ojpc.2012.24030
Abstract: Anodic polarization of nickel was studied by potentiostatic technique in neutral media in presence of two macrocyclic ligands. Pit initiation was detected by measuring pitting potential, Ep and the charge transfer, Q during the anodic polarization. Initiation of pitting and Q were found to be dependent on the structure and concentrations of inhibitors. Under steady state conditions, the inhibition efficiency was in the order 1, 4, 8, 11 tetraazacyclotetradecane (cyclam) > N, N’-bis (2-aminoethyl) 1, 3-propandiamine (2,3,2-tet) due to macrocyclic effect. These findings were confirmed by fitting the data to different adsorption isotherms. Adsorption on nickel surface was obeyed kinetic-thermodynamic model for the two inhibitors. Influence of [Cl] on corrosion behavior of nickel in sulphate solution containing inhibitors was investigated. A mechanism involving three competitive equilibria of dissolution of nickel in presence and absence of the inhibitors was proposed. Empirical and theoretical kinetic equations were compared and discussed. There is a good agreement between the calculated and observed rate constants.
Characterization of Plasma Sprayed Hydroxyapatite Coatings on AISI 316L SS and Titanium Substrate and their Corrosion Behavior in Simulated Body Fluid  [PDF]
Manoj Mittal, S. K. Nath, Satya Prakash
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2011, DOI: 10.4236/jmmce.2011.1011079
Abstract: In order to increase the bone bioactivity of metallic implants, hydroxyapatite (HA: Ca10(PO4)2(OH)6) is often coated on their surface so that real bond with surrounding bone tissue can be formed. In present study, HA coatings were deposited on AISI 316L SS and titanium using shrouded plasma spray process. The coated specimens were subjected to X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FE-SEM/EDAX). The polarization studies in simulated body fluid (SBF) were conducted to evaluate the corrosion resistance of bare and coated specimens. It was found that the hydroxyapatite coating provided excellent corrosion resistance. The resistance to corrosion was found independent on substrates
Nonlinear Polarization Rotation Characteristic Phenomenon in a Bulk Semiconductor Optical Amplifier  [PDF]
Xianghua Feng, Jiarong Ji, Guomin Zhang
Optics and Photonics Journal (OPJ) , 2013, DOI: 10.4236/opj.2013.32B045
Abstract:

The phenomena of polarization rotation induced by self-modulation in semiconductor optical amplifier (SOA) are analyzed theoretically. The relationship between polarization parameters and gain as well as phase is obtained by the correlation parameter of ellipse polarization and SOA nonlinearity polarization rotation theory. The experiment employs polarizer drive by walking electromotor and power meter, the light power of 360 degree is measured. The transformation law of output polarization power components is found for obvious polarization rotation in the selected coordinate axes based on connection of polarization state in difference axes. Using this law make the manipulation easily on getting ideal polarization state. It can offer a fine method to realize all-optical switch and other logic elements in experiment. This work is of great significance for the applications of SOA nonlinear polarization rotation at high-speed all-optical signal processing and all-optical logic gate.

Interferometry Analysis of Cellophane Birefringence  [PDF]
Dickson M. Kinyua, Geoffrey K. Rurimo, Patrick M. Karimi, Stephen N. Maina, Calvin F. Ominde
Optics and Photonics Journal (OPJ) , 2013, DOI: 10.4236/opj.2013.36052
Abstract:

This paper reports on a simple approach of determining the ability of a transparent material, such as cellophane to rotate the direction of polarization of a light beam. In order to determine the birefringence of such a material, a Mach-Zehnder interferometer is used to generate interference patterns when the cellophane sheet is mounted on one arm such as to intercept a portion of the laser beam. The recorded interferograms show a phase shift which is calculated to be 0.98π radians. By rotating the cellophane sheet on the object beam, the fringe separation is measured for different angles and the values used to calculate the ordinary and extraordinary refractive indices as 1.4721 ± 0.0002 and 1.4680 ± 0.0002 respectively at 632.8 nm wavelength. A surface error of approximately λ/16 (peak to valley) is measured from the recorded interferograms. Because of its sufficient birefringence and small thickness of 24 μm, cellophane can be used to fabricate special polarization pupil masks by cutting and aligning different cellophane structures appropriately.

Free Volume in Membranes: Viscosity or Tension?  [PDF]
V. S. Markin, F. Sachs
Open Journal of Biophysics (OJBIPHY) , 2015, DOI: 10.4236/ojbiphy.2015.53007
Abstract: Many papers have used fluorescent probe diffusion to infer membrane viscosity but the measurement is actually an assay of the free volume of the membrane. The free volume is also related to the membrane tension. Thus, changes in probe mobility refer equally well to changes in membrane tension. In complicated structures like cell membranes, it appears more intuitive to consider variations in free volume as referring to the effect of domains structures and interactions with the cytoskeleton than changes in viscosity since tension is a state variable and viscosity is not.
2D Analytical Model for Direct Ethanol Fuel Cell Performance Prediction  [PDF]
Saeed Heysiattalab, Mohsen Shakeri
Smart Grid and Renewable Energy (SGRE) , 2011, DOI: 10.4236/sgre.2011.24049
Abstract: Analytical models provide useful information for researchers to study fuel cell function. In this paper, it’s aimed to present a 2D analytical model for direct ethanol fuel cell (DEFC) performance. The model included equations inside diffusion layer, catalyst layer, and Ethanol cross-over through membrane, which all have been solved. Analytical model has been validated by some experimental trials. The results showed that there is proper agreement between experimental and analytical curves. Furthermore, by increasing current density, cathodic over potential will remain zero but anodic over potential will increase up to certain value. The model showed that Ethanol concentration changes almost linearly inside anode channel.
Ultrasonic Corrosion-Anodization: Electrochemical Cell Design and Process Range Testing  [PDF]
Kyriakos Roushia, Kyriaki Polychronopoulou, Charalambos C. Doumanidis
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2012, DOI: 10.4236/jsemat.2012.21001
Abstract: Titanium was used in the present work as the test metal for the first ultrasonic corrosion anodization (UCA) study, because of its important photonics and biomedical applications. The electrochemical cell design was implemented and tested under various experimental conditions combinations (e.g. electrolyte concentration, duration, temperature, ultra-sound presence or absence, oxygen presence, etc) in order to investigate the effect of those parameters in the cracks propagation in Ti-foils. It was found that an increase of cracks takes place when oxygen is provided in the electrolyte solution and when ultrasound is applied. The results presented in the current study could be exploitable towards design of materials having dendritic morphologies, applicable in a wide range of processes from photovoltaics to biocompatible materials.
The Cell Sorting Process of Xenopus Gastrula Cells Progresses in a Stepwise Fashion Involving Concentrification and Polarization  [PDF]
Ayano Harata, Takashi Matsuzaki, Koichi Ozaki, Setsunosuke Ihara
CellBio (CellBio) , 2013, DOI: 10.4236/cellbio.2013.22007
Abstract:

Animal pole cells (AC) and vegetal pole cells (VC) dissociated from early Xenopus gastrulae were intermingled, and the cell sorting process occurring within the aggregate was analyzed. The overall process of cell sorting was found to morphologically consist of two steps, “concentrification” and “polarization”, as designated here. First, AC and VC clusters emerged at random positions in the aggregate, and the individual clusters gradually assembled themselves by 5 hours in culture (5 hC), forming a concentric arrangement, in which the AC cluster was enveloped by the VC cluster. This concentrification step is essentially consistent with the descriptions in earlier studies. As the next step, the AC and VC clusters moved up and down from 7.5 to 12 hC, resulting in the vertical polarization, namely, a serial array just like in vivo. Immunohistochemical analyses showed that AC expressed both C- and E-cadherins, while VC only expressed C-cadherin, as in vivo, suggesting the normal participation of cadherin system. On the other hand, the actin localization showed that the actin bundles accumulated at the edge of the AC cluster until the concentrification was completed, and gradually decreased during the polarization step. Another important finding was that AC cluster could generate cartilage tissues during the long-term (7 days) culture, evidence for a healthy inductive interaction between the AC and VC. Taken together, the present experimental system allows the AC and VC to be viable and grow into an embryo-like organization.

Study the Effect of Ruthenium Dye Layer on Negative Capacitance in Solar Cells Based on the Nc-TiO2 Semiconducting Polymer Heterojunction  [PDF]
H. Al-Dmour
Materials Sciences and Applications (MSA) , 2015, DOI: 10.4236/msa.2015.61012
Abstract: We report the effect of ruthenium dye on negative capacitance of nanocrystalline titanium dioxide/poly(3-hexyl thiophene), nc-TiO2/P3HT, heterojunction solar cells. It has been found that the low frequency capacitance reaches a high positive value and then drop to the negative region. In P3HT/Ru-Dye/nc-TiO2 solar cells, the negative capacitance is observed under very low forward bias condition unlike the negative capacitance in P3HT/ncTiO2 solar cells. That is attributed to the difference of the concentration of dipole and presence of depletion region at interface between the P3HT and nc-TiO2.
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