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1.
Bending of optical fiber leads to an induced-anisotropy in the index profile that influences many important guiding fiber parameters. An analytical method is described for the measurement of refractive-index-wavelength dispersion in bent optical fibers. Multiple-beam Fizeau fringes technique at transmission is used to analyze the opto-mechanical properties and induced-index anisotropy in a standard single-mode fiber undergoes pure mechanical macrobending. The shift in Fizeau fringes is employed to evaluate the dispersion of the cladding material of the bent fiber. The radial variations in Cauchy’s coefficients and the associated variations of some fiber parameters due to macrobending are carried out. The radial profiles of some material parameters such as oscillation energy, dispersion energy, lattice energy and material dispersion are measured as well. The presented method is capable to achieve quantitative and qualitative measurements, which is not available with other methods. The method has a good index resolution in the order of 10−4 and spatial resolution of 1.3 μm. 相似文献
2.
New chaos generators 总被引:1,自引:0,他引:1
Originating from a sinusoidal oscillator circuit that employs the current feedback op amp (CFOA) as the active building block, a new chaos generator that utilizes a discrete nonlinear device of asymmetrical nonlinearity is proposed. Two different positions of the nonlinearity within the circuit structure are investigated. A slight modification incorporating the addition of a single resistor to the generator is shown to facilitate its tuning and affect the dynamics of its chaotic behavior. Experimental laboratory results agree well with PSpice simulations, and both are included. 相似文献
3.
The study deals with the effect of an applied transverse magnetic field on the dynamics and parameters of the focused and expanded plasma in a coaxial discharge. The experimental results were found with a 3 kJ Plasma focus device of a Mather geometry. The discharge takes place in hydrogen gas with base pressure of 0.5 Torr. The experiments are conducted with a 10 kV bank voltage, which corresponds to 100 kA peak discharge current with rise time 8 μs. Helmholtz magnetic coils are placed outside the expansions chamber to produce a transverse magnetic field with intensity 280 G perpendicular to the plasma expanded from the coaxial electrodes. The investigations have shown that the plasma flow along the expansion chamber axis is restricted when applying the externally transverse magnetic field and the maximum axial velocity of the expanded plasma is decreased by 33%. X-ray probe has been used to measure the focused plasma electron temperature (Te). The experimental results and the calculations showed that Te is decreased from 2.2 keV to 800 eV with the application of a transverse magnetic field. The expanded plasma electron temperature and density have been measured by an electric double probe, the results cleared that the expanded plasma electron temperature is decreased by 2.6 times while its density is increased by 9 times, when a transverse magnetic field is applied. 相似文献
4.
Zusammenfassung Zu den schwierigsten Aufgaben der toxikologischen Analyse gehört die rasche und sichere Isolierung und Identifizierung organischer Basen aus dem Untersuchungsmaterial. Mit einem entsprechenden Extraktionsverfahren oder durch Fällung mit Tetraphenylborat in einem systematischen Analysengang können sehr günstige Ausbeuten erzielt werden. Die Reinigung der Rohextrakte oder -fällungen erfolgt prinzipiell mittels Dünnschichtchromatographie. Aus den Tetraphenylboratkomplexen werden dabei auf den Kieselgelschichten die reinen Basen in Freiheit gesetzt. An Hand derR
f- Wert-Tabellen ist eine Identifizierung möglich, wobei Substanzen mit gleichemR
f- Wert durch fraktionierte Extraktion bei verschiedenem pH getrennt werden können. Eine weitere Identifizierung kann mit Hilfe der UV-Spektren erfolgen.
Summary Among the most difficult problems of toxicological analysis are the rapid and reliable isolation and identification of organic bases from the material under examination. Very satisfactory yields can be obtained by means of a suitable extraction procedure or through precipitation with tetraphenyl borate in a systematic scheme of analysis. The purification of the crude extracts or precipitates is accomplished fundamentally by thin layer chromotography. The pure bases are liberated on the silica layers from the tetraphenyl borate complexes. An identification is possible through reference toR f- tables; substances with likeR f value can be separated by fractional extraction at different pH values. A further identification can be made with the aid of UV spectra.
Résumé L'isolement rapide et sûr des bases organiques dans une substance à l'étude et leur identification représentent l'un des problèmes les plus difficiles de l'analyse toxicologique. On peut atteindre des rendements très satisfaisants avec un procédé d'extraction analogue ou par précipitation par le tétraphénylborure dans un processus d'analyse systématique. La purification de l'extrait brut ou des produits de précipitation s'effectue principalement au moyen de la chromatographie en couche mince. Les bases pures sont libérées des complexes au tétraphénylborure en opérant sur couches en gel de silice. On peut faire une identification en se servant des valeurs desR f figurant dans les tables, ce qui permet de séparer les substances de mêmeR f par extraction fractionnée à des pH différents. Une identification plus poussée peut avoir lieu à l'aide des spectres UV.相似文献
5.
Mezna Saleh Altowyan Saied M. Soliman Matti Haukka Nora Hamad Al-Shaalan Aminah A. Alkharboush Assem Barakat 《Molecules (Basel, Switzerland)》2022,27(13)
In the present work, a novel heterocyclic hybrid of a spirooxindole system was synthesized via the attachment of ferrocene and triazole motifs into an azomethine ylide by [3 + 2] cycloaddition reaction protocol. The X-ray structure of the heterocyclic hybrid (1″R,2″S,3R)-2″-(1-(3-chloro-4-fluorophenyl)-5-methyl-1H-1,2,3-triazole-4-carbonyl)-5-methyl-1″-(ferrocin-2-yl)-1″,2″,5″,6″,7″,7a″-hexahydrospiro[indoline-3,3″-pyrrolizin]-2-one revealed very well the expected structure, by using different analytical tools (FTIR and NMR spectroscopy). It crystallized in the triclinic-crystal system and the P-1-space group. The unit cell parameters are a = 9.1442(2) Å, b = 12.0872(3) Å, c = 14.1223(4) Å, α = 102.1700(10)°, β = 97.4190(10)°, γ = 99.1600(10)°, and V = 1484.81(7) Å3. There are two molecules per unit cell and one formula unit per asymmetric unit. Hirshfeld analysis was used to study the molecular packing of the heterocyclic hybrid. H···H (50.8%), H···C (14.2%), Cl···H (8.9%), O···H (7.3%), and N···H (5.1%) are the most dominant intermolecular contacts in the crystal structure. O···H, N···H, H···C, F···H, F···C, and O···O are the only contacts that have the characteristic features of short and significant interactions. AIM study indicated predominant covalent characters for the Fe–C interactions. Also, the electron density (ρ(r)) at the bond critical point correlated inversely with the Fe–C distances. 相似文献
6.
M. Mostafa A. F. El-gharbawy M. A. El-Absy S. E. Soliman F. A. Aly 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(3):1089-1097
A radiochemical method was investigated for separation and preconcentration of radioiodine from alkaline radiotellurium waste solution as Ag125I followed by recovery of 125I into aqueous NH3 solution and final purification by wet distillation. 125I–123mTe radiotracer solution (5 M NaOH) was equilibrated with prepared silver granules for different times and it was found that 125I was quantitatively removed from the aqueous phase after 7.0 h. The 125I-loaded silver was then equilibrated with ammonia solution in the presence of one of different reducing agents (namely, sodium borohydride, dextrose and zinc dust). Different concentrations of NH3 solution and reducing agents were studied. Quantitative recovery of 125I in the aqueous phase was achieved after 1.0 h of equilibration of 125I-loaded silver granules with 2.7M NH3 solution in the presence of Zn dust with a Zn:Ag molar ratio of 0.5. Purification of the recovered 125I was carried out by wet distillation from 20 % H2SO4 in the presence of H2O2. The distilled off 125I was received in a mixture solution of 0.1M NaOH and 0.01M Na2S2O3 with a radionuclidic purity of ≥99.99 %, radiochemical purity of ~98.8 % (as I? anions) and pH-value of ~13. 相似文献
7.
A. M. M. Soliman A. Khodairy E. A. Ahmed 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):649-665
The reaction of N-chloroacetyl derivatives 6-10 with morpholine yielded N-morpholin-1-yl acetyl derivatives 11-15 , which were subjected to Thorpe-Zieler cyclization with sodium tert -butoxide to produce the corresponding condensed pyridin-2(1H)-one derivatives 16-20 . Treatment of compounds 1 , 6-10 with either malononitrile or p -chlorobenzylidinemalononitrile in presence of triethylamine, afforded the corresponding pyrimidines 21-25 , 27 and pyridine derivative 26 respectively. Moreover compound 1 a was treated with ethyl isothiocyanoacetate to give the corresponding piprazine derivative 28 . 相似文献
8.
Soher S. Maigali Mohamed H. Arief Marwa EL-Hussieny Fouad M. Soliman 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):190-204
Abstract The reaction of nucleophilic phosphacumulene ylides with visnaginone and khellinone afforded the corresponding phosphanylidene and furochromene derivatives. Moreover, pyranochromenes were obtained from the reaction of chromene carbaldehydes with phosphacumulenes. On the other hand, the phosphanylidene-cyclobutylidenes and their dimers were produced from the reaction of furochromene carbaldehydes with the same phosphonium reagents. 相似文献
9.
The reaction of cycloalkylidenemalononitriles 1a–c with some active methylene reagents as well as cycloalkanones in boiling ethanol containing piperidine catalyst affords a series of new spiro heterocyclic systems. 相似文献
10.
E. M. S. Azzam A. M. Badawi A. R. E. Alawady A. Soliman 《Journal of Dispersion Science and Technology》2013,34(4):540-547
The purpose of this work is to study the self-assembling of some synthesized thiol surfactants namely (mercaptopropane-, mercaptohexane-, mercaptooctane-, and mercaptodecane sodium sulfonate) on the fabricated gold nanoparticles. The self-assembling of these surfactants on gold nanoparticles characterized using different techniques such as FTIR spectroscopy, UV spectroscopy, and transmission electron microscopy (TEM). Spectroscopic evidence suggests that the synthesized thiol surfactants have been attached to the gold nanoparticles. The effect of self-assembling of these surfactants on the size of the gold nanoparticles was studied using TEM images. The growth of the gold nanoparticles was investigated with respect to the increase of alkyl chain in the synthesized thiol surfactants. The results show that the stabilization of gold nanoparticles was affected by the increase in alkyl chain length of these surfactants. The effect of gold nanoparticles on the interfacial tension and the emulsion stability of these surfactants with crude oil was studied. 相似文献