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1.
We report an experimental observation of the influence of concentration of Er3+ ions in an Erbiumdoped silica fiber on the spectral characteristics of an erbium fiber laser. Our basic conclusion is that an increase of erbium concentration in the fiber results in the laser optical spectrum narrowing. We also discuss possible mechanisms responsible for this effect. 相似文献
2.
B. Király F. Tárkányi S. Takács Z. Kovács 《Journal of Radioanalytical and Nuclear Chemistry》2006,270(2):369-378
Summary Excitation functions of proton induced nuclear reactions on natural Te were investigated up to 18 MeV. Cross sections for
production of 121,123,124,126,128,130gI and 121gTe were measured. The new experimental data were compared with the results of ALICE-IPPE model calculations and with data
found in the literature and measured on natural or enriched Te targets. The new data can be effectively used for validation
of recommended cross sections of medically relevant 123I and 124I. 相似文献
3.
Experimental data suggest that Resveratrol, a compound found in grapes and other fruits may influence cell proliferation and apoptosis. The aim of our experiments was to study the effect of Resveratrol on tumor cell cultures and an endothelial cell culture in order to examine the effect of various doses of this compound on active cell death and cell proliferation. Human tumor (HT-29, SW-620, HT-1080) and endothelial (HUV-EC-C) cells were treated with various doses of (0.1 to 100.0 microg/ml) Resveratrol in vitro. Cell number, apoptotic and mitotic index was measured 24, 48 and 72 h after treatment. Low doses (0.1-1.0 microg/ml) of Resveratrol enhance cell proliferation, higher doses (10.0-100.0 microg/ml) induce apoptosis and decrease mitotic activity, which is reflected in changes of cell number. Resveratrol influences dose dependently the proliferative and apoptotic activity of human tumor and endothelial cells. The possible role of formaldehyde in the mechanism of action of Resveratrol is discussed. 相似文献
4.
A. Kiréva 《Mikrochimica acta》1976,66(1-2):211-215
Résumé Le présent travail constitue une application analytique de nos recherches sur l'interaction des complexes interhalogénés de l'iode au moyen de diantipyrilméthane (DAM). On à étudié les conditions d'échange des ligands chlore et iode dans le complexe extrasphérique DAMH3 [ICl2]3. Sur la base de cet échange on a élaboré une méthode photométrique de détermination de microquantités d'ions iodures, soit 1 à 10g d'ions iodures par ml. Les ions Br–, Cl–, NO3
–, SO4
2, C2O4
2– ne gênent pas la détermination.
Investigation of the interaction of certain iodine complexes by means of diantipyrilmethane (DAM). II
Summary The present paper constitutes an analytical application of our studies on the interaction of interhalogen complexes of iodine by means of diantipyrilmethane (DAM). The exchange conditions of the chlorine and iodine ligands in the extraspheric complex DAMH3 (ICl2)3 have been examined. On the basis of this exchange a photometric method of determining microquantities of iodide ions (1 to 10g iodide ions per ml) has been developed. The ions Br–, Cl–, SO4 2–, C2O4 2– do not interfere with the determination.
Zusammenfassung Die Ergebnisse unserer Untersuchungen über die Reaktion von Interhalogenkomplexen des Jods mit Diantipyrilmethan (DAM) wurden für analytische Zwecke verwendet. Die Bedingungen für den Austausch der Liganden Chlor und Jod im außersphärischen Komplex (DAM)H3 · [JCl2]3 wurden untersucht. Auf der Grundlage dieses Austausches wurde eine photometrische Methode zur Bestimmung von Mikromengen, d. h. 1–10g Jodid/ml ausgearbeitet. Br–, Cl–, NO3 –, SO4 2–, C2O4 2– stören die Bestimmung nicht.相似文献
5.
6.
Ayşegül Doğan Emirhan Nemutlu M. Aykut Özek Hakan Eroğlu Sedef Kır M. Sinan Beksaç 《Chromatographia》2013,76(21-22):1513-1519
Pregnancy alters pharmacokinetic profile of many drugs, because of altering body volume and metabolism rate. Therefore, dosage rates and concentrations of drugs must be controlled during pregnancy. Here, we identified the pharmacokinetic profile of pre-operatively given cefepime in caesarean section and gynecological operations using a simple, rapid, cost-effective and valid liquid chromatographic method. The chromatographic separation was performed using 40 mM, pH 3.2 phosphate buffer containing 6 % methanol as mobile phase at 0.30 mL min?1 flow rate. Gradient elution with methanol was applied to get shorter analysis time without any interference from plasma endogens. During analyses, temperature of column, autosampler and detector were set as 30, 10 and 40 °C, respectively. The detection wavelength was 260 nm and ceftizoxime was used as internal standard. At the optimum conditions, the cefepime analysis from plasma samples was completed in 7 min. Cefepime was extracted from plasma samples using perchloric acid with a very high recovery rate (99.3 %). The method was fully validated according to the Food and Drug Administration guidelines for bioanalytical method validation, and found to be selective, linear, repeatable, reproducible and robust. After validation studies, the method was applied to five caesarean-sectioned and four non-pregnant sectioned women treated with pre-operative, prophylactic single intravenous dose of cefepime (1 g Maxipime®) in order to determine pharmacokinetic profile of cefepime. Peak serum concentrations of cefepime in caesarean-sectioned women at the arterial port after infusion was 70.11 ± 10.74 μg mL?1. The mean elimination half-life, volume of distribution and calculated area under the concentration–time curve (AUC)0–∞ were 1.10 ± 0.23 h, 14.22 ± 2.29 L and 101.55 ± 10.99 μg h mL?1 for caesarean-sectioned women; and 1.14 ± 0.21 h, 14.76 ± 2.92 L and 104.71 ± 36.34 μg h mL?1 for non-pregnant sectioned women, respectively. The area under curve, elimination half-life, maximum plasma concentration and the mean distribution volume of cefepime were not changed in case of pregnancy. 相似文献
7.
An eigenfunction expansion of the non-selfadjoint Sturm–Liouville operator with a singular potential
Esra Kir Arpat 《Journal of mathematical chemistry》2013,51(8):2196-2213
In this paper, we consider the operator $L$ L generated in $L^{2}\left( \mathbb{R }_{+}\right) $ L 2 R + by the differential expression $$\begin{aligned} l\left( y\right) =-y^{\prime \prime }+\left[ \frac{\nu ^{2}-\frac{1}{4}}{x^{2}}+q\left( x\right) \right] y,\,\,x\in \mathbb{R }_{+}:=\left( 0,\infty \right) \end{aligned}$$ l y = - y ' ' + ν 2 - 1 4 x 2 + q x y , x ∈ R + : = 0 , ∞ and the boundary condition $$\begin{aligned} \underset{x\rightarrow 0}{\lim }x^{-\nu -\frac{1}{2}}y\left( x\right) =1, \end{aligned}$$ lim x → 0 x - ν - 1 2 y x = 1 , where $q$ q is a complex valued function and $\nu $ ν is a complex number with $Re\nu >0$ R e ν > 0 . We have proved a spectral expansion of L in terms of the principal functions under the condition $$\begin{aligned} \underset{x\in \mathbb{R }_{+}}{Sup}\left\{ e^{\epsilon \sqrt{x}}\left| q(x)\right| \right\} <\infty , \epsilon >0 \end{aligned}$$ S u p x ∈ R + e ? x q ( x ) < ∞ , ? > 0 taking into account the spectral singularities. We have also investigated the convergence of the spectral expansion. 相似文献
8.
An experimental and theoretical investigation of the nonlinear transmission coefficient of ytterbium-holmium codoped silica fiber (YHF) at continuous-wave 978-nm pumping is reported. An analysis of the fiber absorption and luminescence spectra under 978-nm pumping reveals a variety of processes participating in the mixed (Yb3+, Ho3+) system: the energy transfer Yb3+ → Ho3+, the up-conversion and excited-state absorption in Ho3+, and the luminescence quenching due to the presence of Yb3+-Yb3+ ion pairs. These processes are shown to notably affect the transmission coefficient of YHF, which is reflected in a pronounced modification of its dependences on pump power, fiber length, and dopant concentrations, in comparison with the case of purely ytterbium-doped fiber (YF). A modeling of the experimentally measured dependences of the YHF transmission coefficient on pump power and fiber length allows us to obtain the coefficients addressing the energy transfer process Yb3+ → Ho3+ in YHF. A comparison of YHF and YF at the same pumping conditions reveals that, in YHF, a considerable part of the pump power absorbed in the Yb3+ subsystem is transferred into the Ho3+ subsystem; this results in an effective population of its 5 I 7 state and makes YHF promising for 2-μm lasing and amplifying. 相似文献
9.
We consider a magnetic impurity coupled to both fermionic quasiparticles with a pseudogap density of states and bosonic spin fluctuations. Using renormalization group and large-N calculations we investigate the phase diagram of the resulting Fermi-Bose Kondo model. We show that the Kondo temperature is strongly reduced by low-energy spin fluctuations, and make connections to experiments in cuprate superconductors. Furthermore, we derive an exact exponent for the critical behavior of the conduction electron T matrix, and propose our findings to be relevant for certain scenarios of local quantum criticality in heavy-fermion metals. 相似文献
10.
The features of superfluorescence (SF) in nanoclusters, which consist of a few neighboring particles interacting with each other by exchange or/and electrostatic forces, are investigated theoretically. It is shown that there are two types of cooperatively SF depending on the ratio between the linear size of a nanocluster and the cooperative interaction range. Experiments on cooperative luminescence in Ytterbium-doped silica fibers are analyzed. It is shown that the intensity of cooperative SF in such a system should be proportional to the fourth degree of Ytterbium concentration. 相似文献