Optimization of Adsorbent Layer Type and Developing Solvent in Coccidiostats Sample Preparation with Procedure of Solvent Front Position Extraction

Coccidiostats are drugs used against coccidiosis, a common disease among breeding animals. Their widespread application leads to the appearance of their residues in food, which is potentially harmful for human health and life. The European Union has established limits of concentrations of these drugs in premixtures and food. Nowadays, there are many methods for monitoring coccidiostats’ presence in market products, but their frequent weakness is sample preparation. Solvent Front Position Extraction is a planar chromatography-based sample preparation method that allows for effective assay of samples with coccidiostats when coupled with LC-MS/MS. The purpose of this research was to find common conditions for the effective isolation of eight coccidiostats from biological sample components with both lower and higher retention than the substances of interest. The acquired results were used for effective isolation of monensin and salinomycin from the premixture samples and allowed for their quantitative determination. The application of a semi-automatic device for the development of chromatograms positively impacted the results, confirming the effectiveness of the method for determining coccidiostats in biological samples.     

Thermodynamic properties of a diluted Heisenberg ferromagnet with interaction anisotropy—Magnetocaloric point of view

The thermodynamics of a site-diluted ferromagnetic Heisenberg model for spin S=1/2 with interaction anisotropy in spin space is investigated. The study is aimed at presenting the magnetocaloric properties of such a model, including the entropy and temperature changes in magnetization/demagnetization processes, generalized Grüneisen ratio as well as the quantities characterizing the efficiency of magnetic cooling cycles. The results are obtained using pair approximation (PA) method and extensively compared with the molecular field approximation (MFA) calculations. The importance of interaction anisotropy and site-dilution is discussed. The inadequacy of the MFA approach (even on the qualitative level) is found for selected quantities, while PA provides the results which are consistent with the experimentally observed behavior.     

Nonlinear Cauchy-Riemann operators in

This paper has arisen from an effort to provide a comprehensive and unifying development of the -theory of quasiconformal mappings in . The governing equations for these mappings form nonlinear differential systems of the first order, analogous in many respects to the Cauchy-Riemann equations in the complex plane. This approach demands that one must work out certain variational integrals involving the Jacobian determinant. Guided by such integrals, we introduce two nonlinear differential operators, denoted by and , which act on weakly differentiable deformations of a domain .

Solutions to the so-called Cauchy-Riemann equations and are simply conformal deformations preserving and reversing orientation, respectively. These operators, though genuinely nonlinear, possess the important feature of being rank-one convex. Among the many desirable properties, we give the fundamental -estimate

In quest of the best constant , we are faced with fascinating problems regarding quasiconvexity of some related variational functionals. Applications to quasiconformal mappings are indicated.

     

Functional differential equations

The method of quasilinearization is a well-known technique for obtaining approximate solutions of nonlinear differential equations. In this paper we apply this technique to functional differential problems. It is shown that linear iterations converge to the unique solution and this convergence is superlinear.     

Application of the okahara cyclization to the preparation of crown ethers with aromatic units

A series of crown ethers with single benzene, naphthalene, biphenyl and binaphthyl units are prepared by the intramolecular Okahara cyclization of appropriate symmetrical diols. The method is used to synthesize new crown ether compounds and to prepare previously-reported crown ethers in improved yields.     

Alternative,simple route to hydroxymethyl crown ethers

Components for polymer-supported catalysts, hydroxymethyl-substituted 15-crown-5 and 18-crown-6 were prepared from readily available starting materials on relatively simple way.     

Bestimmung von Wolfram mit dem kapazitiv gekoppelten Mikrowellenplasma (CMP)

Zusammenfassung Die Bestimmung von Wolfram im kapazitiv gekoppelten Mikrowellenplasma (CMP) wurde untersucht. In unserem N₂-Plasma beträgt die kinetische Gastemperatur 4450 K, die Anregungstemperatur bis zu 5590 K. Die relativen Intensitäten von 45 Atomlinien des Wolframs im Bereich 450 bis 185 nm werden angegeben. Ionenlinien sind nicht zu beobachten. Analytisch am besten geeignet ist die Linie WI 400,875 nm. Mit ihr sind in wäßriger Lösung 1,5 ppm W nachweisbar, in Gegenwart von 0,01 M Na⁺ noch 5 ppm. Neben viel Ti ist die Linie WI 407,436 nm vorzuziehen. — Die Wirkungen und Wechselwirkungen von Alkaligehalt, Generatorleistung, Beobachtungshöhe und Zerstäuberdruck auf die Linienintensität wurden mit einem Faktorenversuchsplan untersucht und ihre optimale Einstellung nach dem Simplexverfahren ermittelt. — In Stählen und anderen Legierungen wurden 0,2–80 % W bestimmt.Wir danken der Deutschen Forschungsgemeinschaft für die Gewährung von Sachbeihilfen, den Herren M. Brühl-Saager, U. Tracht und E. Antfang für ihre Mithilfe und Herrn Prof. F. Umland für die Förderung unserer Arbeiten.     

Determination of tungsten by direct current plasma atomic emission spectrometry

The determination of tungsten in steels and alloys with the three-electrode direct current plasma (DCP) “spectrajet” was investigated. The relative intensities of 17 spectral lines of tungsten and several possible interfering lines of its concomitants are listed. WI 400.875 nm is normally best suited, because the background produced by iron and acid is low and easily compensated for by using a blank solution. The limit of detection c_l in steels is 2 × 10^?3% W for 10 $\text{mg}\text{ml}$ of sample. The line W I 407.436 nm is preferred in the presence of much titanium. For the purpose considered the DCP provides about the same power of detection as the more expensive inductively coupled plasma (ICP), but its observation zone is less well buffered against influences from the matrix.