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101.
Sabriye Acikgoz Bukem Bilen Mustafa Muamer Demir Yusuf Ziya Menceloglu Yani Skarlatos Gulen Aktas Mehmet Naci Inci 《Optical Review》2008,15(2):84-90
Humidity induced change in the refractive index and thickness of the polyethylene glycol (PEG) coatings are in situ investigated for a range from 10 to 95%, using an optical waveguide spectroscopic technique. It is experimentally demonstrated
that, upon humidity change, the optical and swelling characteristics of the PEG coatings can be employed to build a plastic
fibre optic humidity sensor. The sensing mechanism is based on the humidity induced change in the refractive index of the
PEG film, which is directly coated onto a polished segment of a plastic optical fibre with dip-coating method. It is observed
that PEG, which is a highly hydrophilic material, shows no monotonic linear response to humidity but gives different characteristics
for various ranges of humidity levels both in index of refraction and in thickness. It undergoes a physical phase change from
a semi-crystalline structure to a gel one at around 80% relative humidity. At this phase change point, a drastic decrease
occurs in the index of refraction as well as a drastic increase in the swelling of the PEG film. In addition, PEG coatings
are hydrogenated in a vacuum chamber. It is observed that the hydrogen has a preventing effect on the humidity induced phase
change in PEG coatings. Finally, the possibility of using PEG coatings in construction of a real plastic fibre optic humidity
sensor is discussed. 相似文献
102.
Bauer F Bisplinghoff J Büsser K Busch M Colberg T Demirörs L Dahl C Eversheim PD Eyser O Felden O Gebel R Greiff J Hinterberger F Jonas E Krause H Lehmann C Lindlein J Maier R Meinerzhagen A Pauly C Prasuhn D Rohdjess H Rosendaal D von Rossen P Schirm N Scobel W Ulbrich K Weise E Wolf T Ziegler R;EDDA Collaboration 《Physical review letters》2003,90(14):142301
At the Cooler Synchrotron COSY/Jülich spin-correlation parameters in elastic proton-proton (pp) scattering have been measured with a 2.11 GeV polarized proton beam and a polarized hydrogen atomic beam target. We report results for A(NN), A(SS), and A(SL) for c.m. scattering angles between 30 degrees and 90 degrees. Our data on A(SS)--the first measurement of this observable above 800 MeV--clearly disagrees with predictions of available pp scattering phase-shift solutions while A(NN) and A(SL) are reproduced reasonably well. We show that in the direct reconstruction of the scattering amplitudes from the body of available pp elastic scattering data at 2.1 GeV the number of possible solutions is considerably reduced. 相似文献
103.
H. Rohdjeß F. Bauer J. Bisplinghoff K. Büßer M. Busch T. Colberg L. Demirörs C. Dahl P. D. Eversheim O. Eyser O. Felden R. Gebel J. Greiff F. Hinterberger E. Jonas H. Krause C. Lehmann J. Lindlein R. Maier A. Meinerzhagen C. Pauly D. Prasuhn D. Rosendaal P. von Rossen N. Schirm W. Scobel K. Ulbrich E. Weise T. Wolf R. Ziegler 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):555-558
At the Cooler-Synchrotron COSY/Jülich polarized and unpolarized elastic proton-proton scattering has been investigated with the EDDA-Experiment in the energy range (
-2.5 GeV). By taking scattering data during the acceleration of the beam with a large-acceptance (
-
) detector, precise excitation functions for differential cross-section and analyzing power have been measured in small energy steps with consistent normalization with respect to luminosity and polarization. These data have helped to improve the determination of phase-shifts at higher energies and impose tight quantitative upper bounds on possible resonant contributions to pp elastic scattering, as they might arise from exotic 6-quark configurations. Recently, with polarized beam and target, the spin-correlation parameters
,
, and
have been determined at 10 energies between 0.8 and 2.5 GeV. The observable
has been measured the first time above 800 MeV and our results are in sharp contrast to phase-shift predictions at higher energies.Received: 30 September 2002, Published online: 22 October 2003PACS:
24.70. + s Polarization phenomena in reactions - 25.40.Cm Elastic proton scattering - 11.80.Et Partial-wave analysis - 13.75.Cs Nucleon-nucleon interactions (including antinucleons, deuterons, etc.) 相似文献
104.
[reaction: see text] A series of water-soluble green perylenediimide (PDI) dyes have been synthesized. On red light excitation, these dyes were shown to be efficient generators of singlet oxygen, and in cell culture media, they were shown to display significant light-induced cytotoxic effects on the human erythroleukemia cell line (K-562). It appears that highly versatile PDI dyes are likely to find new applications in photodynamic therapy. 相似文献
105.
A liquid chromatographic method has been described for the determination of total vitamin C, ascorbic acid (AA) and dehydroascorbic acid (DHAA) in fruits and vegetables. The complete separation of AA and DHAA could be achieved on a C18 column using 0.2 M KH2PO4 (pH adjusted to 2.4 with H3PO4) as the mobile phase at a flow-rate of 0.5 ml/min. Since the detection sensitivity was poor for DHAA even at 210 nm, it was estimated as the difference between the total AA after DHAA reduction and AA content of the original sample, using dithiothreitol (DTT) as the precolumn reductant. The reaction times for the complete conversion of DHAA to AA at room temperatures were 150, 120, 90 and 75 min for 1, 2, 4 and 8 mmol DTT per mmol of DHAA, respectively. The percentage recovery ranged from 81.7 to 105.9. AA contents of some selected fruits and vegetables were analyzed comparatively by liquid chromatography and enzymatic assay to validate the method. 相似文献
106.
The interaction of lithium dodecyl sulfate (LiDS) and sodium dodecyl sulfate (SDS) with poly(ethylene oxide) (PEO) has been
studied with 16-doxyl stearic acid (16-DS) in aqueous solution by electron paramagnetic resonance (EPR). The rotational correlation
times τc and nitrogen hyperfine coupling constantsA
N versus the surfactant concentration with and without PEO have been calculated for different concentrations of 16-DS by our
single-domain simulation program and EPRSIM program. Since the results of single-domain simulations were insufficient in pronounced
changing the interval of τc andA
N values, spectra were also simulated with two and three domains to get better insight about domains. Better-fit results were
found in these simulations. Data obtained from simulations revealed the effects of the polymer and surfactant counterion on
the micelle formation and aggregation percentages. At about 8 mM SDS and about 12 mM LiDS concentrations, the presence of
polymer provided more hydrophobic environment for 16-DS and this indicated that the location of the polymer was within the
interface region. With the increase of the surfactant concentration, less hydrophobic environment was obtained for the nitroxide,
which suggested a more open structure for the polymer-surfactant micelles. 相似文献
107.
This paper is concerned with an elementary problem of V. Thébault which has remained unsolved until recently. We offer a natural solution of the problem and relate it to the classical notable configurations of the triangle.Dedicated to the memory of R. Goormaghtigh and V. Thébault 相似文献
108.
Selçuk Demir 《Geometriae Dedicata》2004,105(1):189-207
Let G denote the isometry group of a regular tree of degree ≥3. The notion of congruence subgroup is introduced and finite generation
of the congruence Hecke algebras is proven. Let U be congruence subgroup and
(G; U) be the category of smooth representations of G generated by their U-fixed vectors. We also show that this subcategory is closed under taking subquotients. All these results are analogues of
well-known results in the case of p-adic groups. It is also shown that the category of admissible representation of G is Noetherian in the sense that every subrepresentation of a finitely generated admissible representation is again finitely
generated. Since we want to emphesize the similarities between these groups and p-adic groups, we give the same proofs which also work in the p-adic case whenever possible. 相似文献
109.
110.
M.M. Hanon E. Akman B. Genc Oztoprak M. Gunes Z.A. Taha K.I. Hajim E. Kacar O. Gundogdu A. Demir 《Optics & Laser Technology》2012,44(4):913-922
Alumina ceramics have found wide range of applications from semiconductors, communication technologies, medical devices, automotive to aerospace industries. Processing of alumina ceramics is rather difficult due to its high degree of brittleness, hardness, low thermal diffusivity and conductivity. Rapid improvements in laser technologies in recent years make the laser among the most convenient processing tools for difficult-to-machine materials such as hardened metals, ceramics and composites. This is particularly evident as lasers have become an inexpensive and controllable alternative to conventional hole drilling methods. This paper reports theoretical and experimental results of drilling the alumina ceramic with thicknesses of 5 mm and 10.5 mm using milisecond pulsed Nd:YAG laser. Effects of the laser peak power, pulse duration, repetition rate and focal plane position have been determined using optical and Scanning Electron Microscopy (SEM) images taken from cross-sections of the drilled alumina ceramic samples. In addition to dimensional analysis of the samples, microstructural investigations have also been examined. It has been observed that, the depth of the crater can be controlled as a function of the peak power and the pulse duration for a single laser pulse application without any defect. Crater depth can be increased by increasing the number of laser pulses with some defects. In addition to experimental work, conditions have been simulated using ANYS FLUENT package providing results, which are in good agreement with the experimental results. 相似文献