Spatiotemporal traveling and solitary wave solutions to the generalized nonlinear Schrödinger equation with single- and dual-power law nonlinearity

Nonlinear Dynamics - We generalize previously obtained solutions to the generalized nonlinear Schrödinger equation (NLSE) with cubic-quintic nonlinearity and distributed coefficients to obtain...     

Some new ring-D seco steroids

The Beckmann fragmentation product, 3-methoxy-17-oxo-16,17-secoestra-1,3,5(10)-trien-16-nitrile (2) has been reduced by LAH giving the expected 3-methoxy-17-hydroxy-16,17-secoestra-1,3,5(10-trien-16-amine hydrochloride (3) and 3-methoxy-17-oxa-D-homoestra-1,3,5(10)-trien-16-ol (4), by a presumed neighbouring group participation of 17-OH group in the intermediary formed 16-imino derivative (A). The structure of 4 has been proved by an alternative synthetic route by reducing 3-methoxy-17-oxa-D-homoestra-1,3,5(10)-trien-16-one (7) with di-iso-butylaluminium hydride.     

Theoretical study of cyclic conjugation in phenes: Some hitherto unnoticed features

Summary Cyclic conjugation in phenes is examined by means of theBosanac-Gutman-Aihara method. In contrast to the predictions based on the analysis ofKekulé orClar structures, we find that when going along the hexagons of a phene molecule, cyclic conjugation varies in a rather non-uniform manner. In contrast to a number of other homologous series of benzenoid hydrocarbons, the intensity of cyclic conjugation in phenes increases when going towards the center of the molecule.

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Theoretische Untersuchung der cyclischen Konjugation in Phenen: Einige bisher unbekannte Eigenschaften

Zusammenfassung Die cyclische Konjugation in Phenen wird mittels derBosanac-Gutman-Aihara-Methode untersucht. Im Gegensatz zu auf der Analyse vonKekulé- oderClar-Strukturen beruhenden Voraussagen variiert die cyclische Konjugation entlang der Sechsecke eines Phenmoleküls ziemlich unregelmäßig. Anders als bei anderen homologen benzenoiden Kohlenwasserstoffen nimmt bei Phenen die Intensität der cyclischen Konjugation zum Zentrum des Moleküls hin zu.

     

Investigation of isothermal bulk polymerization ofo-alkyaryl methacrylates by DSC

The kinetics of the AIBN-initiated free radical bulk polymerization of fiveo-alkylphenyl methacrylates was studied by means of DSC in the temperature range 353–373 K, and the enthalpy of polymerization, the overall reaction rate constant and the activation energy were determined. The results were compared with those published recently on correspondingp-alkylaryl methacrylates. All measured reaction rate constants were found to increase with increasing temperature and to decrease with increasingo-alkyl substituent mass and size. It was shown thato-substituents influence the rates of polymerization to a greater extent thanp-substituents. At about 373 K, all differences in rate, most probably resulting from steric hindrance caused by the alkyl groups, disappear in both series, a phenomenon earlier observed for dimethyl phenyl methacrylates.This work was supported by the Ministry of Science of the Republic of Serbia.     

Role of the solvent in thin-layer chromatography of steroids on alumina

The effects of different binary solvents on the retention behaviour of some steroids in thin-layer chromatography on alumina were studied. The slope of the linear relationship between the retention constant of the steroid and the logarithm of the volume fraction fo the polar component in the binary solvent mixture depends predominantly on the diluent. Linear relationships between the axis intercepts and slopes of particular steroids exists for all chromatographic systems examined. The slope of this relationships is a function of the retention constant of the steroid hydroxyl group.     

Transition metal complexes with thiosemicarbazide-based ligands,IV: Synthesis and molecular structure of 5-nitrosalicylaldehyde S-methylisothiosemicarbazonato-piperidine-copper(II)

Summary The reaction of warmDMF solutions of Cu(II) perchlorate, 5-nitrosalicylaldehyde S-methylisothiosemicarbazone (H₂ L) and piperidine (Pip) yielded the paramagnetic (_eff=2.19 B.M.) Cu(L)Pip complex, whereL is the dianionic form of H₂ L, formed as a result of deprotonation of the phenolic hydroxyl and NH₂ group. Crystal data of the complex are: monoclinic P2₁,a=11.902(4),b=6.765(3),c=11.343(4)Å; =112.92°,V=841.20(8)ų,M=400.9,Z=2,d ₀=1.60 gcm^–3,d _c =1.58 gcm^–3,F(000)=424. The structure was refined to a residualR=0.047. The copper(II) ion is coordinated in a square-planar arrangement by the piperidine nitrogen and the NNO set of donor atoms ofL.

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Komplexe der Übergangsmetalle mit Thiosemicarbazid-Liganden, IV. Synthese und molekulare Struktur von 5-Nitrosalicylaldehyd-S-methylisothiosemicarbazonato-piperidin-kupfer(II)

Zusammenfassung Durch die Reaktion in warmenDMF-Lösungen von Cu(II) Perchlorat, 5-Nitrosalicylaldehyd-S-methylisothiosemicarbazon (H₂ L) und Piperidin (Pip) wurde ein paramagnetischer Komplex (_eff=2.19 B.M.) Cu(L)Pip erhalten, wobeiL nach doppelter Deprotonierung (NH₂- und Phenolhydroxyl-Gruppe) als dianionische Form von H₂ L vorliegt. Die kristallographischen Daten des Komplexes sind: monokline Raumgruppe P2₁,a=11.902(4),b=6.765(3),c=11.343(4)Å, =112.92°;V=841.20ų,M=400.9,Z=2,d ₀=1.60 gcm^–3,d _c =1.58 gcm^–3,F(000)=424. Die struktur wurde bis zu einemR-Wert von 0.047 verfeinert. Die Koordination des Kupfers wird quadratisch-planar über den Piperidin-Stickstoff und die NNO-Donorhülle der Chelatliganden gebildet.

     

Surface recombination in breakdown time delay experiments: Effect of different cathode materials

The late afterglow in nitrogen with iron electrode is studied by the breakdown time delay method, i.e., by measuring the breakdown time delay t_d as a function of the afterglow time . It is proposed that the cause of the secondary electrons initiating the breakdown is the energy of the surface recombination of nitrogen atoms on the iron electrode. The gas-phase and macrokinetic diffusive models are used to describe the experimental breakdown time delay data. By fitting the theoretical curve to the experimental data: (1) it has been confirmed that the recombination on the molybdenum glass is of the second order and the value of the surface recombination coefficient is determined at 4 mbar; (2) it has been shown that the surface recombination on the iron electrode is of the second order, and the effective recombination coefficients are determined; (3) the analytical form of the recombination coefficient as a function of the adsorption characteristics of surfaces and the pressure of the parent gas has been derived. In addition, the orders of surface recombination on the molybdenum-, aluminum-, and gold-plated electrode were determined by the same method.     

Thermal Analysis of Fe(III) Complexes with Salicylaldehyde Semi-, Thiosemi- and S-methylisothiosemi-carbazones

The paper describes the results of differential thermal analysis of the octahedral Fe(III) complexes of the general formula [Fe(HLⁿ)₂]Cl and Fe(HL³)L³, as well as of the corresponding ligands H₂Lⁿ (H₂Lⁿ — tridentate salicylaldehyde semi thiosemi- and S-methylisothiosemi-carabazones with n=1, 2 and 3 respectively). The decomposition of the complexes involving sulphur-containing ligands (H₂L² and H₂L³) starts with sulphur elimination. In case of the complexes [Fe(HL²)]Cl and [Fe(HL³)]Cl sulphur evolves independently, whereas with Fe(HL³)L³ it is eliminated within the SCH₃ group. In the former case, sulphur elimination takes place at the same temperature for both complexes. The change in the coordination mode, being a consequence of the replacement of O by S, has no essential effect on thermal stability of the coordination polyhedron. The complexes involving ONN coordination, realized with the H₂L³ ligand, exhibit a comparatively highest thermal stability of the coordination polyhedron.This revised version was published online in November 2005 with corrections to the Cover Date.     

The stability of non-ionic surfactants and linear alkylbenzene sulfonates in a water matrix and on solid-phase extraction cartridges

The stability of nonylphenol ethoxylates (NPEO), alcohol ethoxylates (AEO), coconut diethanol amides (CDEA) and linear alkylbenzene sulfonates (LAS) in a water matrix and preconcentrated on SPE cartridges was studied. A stability study was carried out in a water matrix (spiked ground water and real-world waste water) comparing different pretreatment procedures (addition of sulfuric acid to pH = 3, preservation with 1% and 3% of formaldehyde). When stored in a water matrix serious qualitative and quantitative changes occurred in waste water during the period of time studied (30 days). The losses of C12-C14 alcohol ethoxylates ranged from 72% to 88% when the sample was preserved with acid and from 17% to 86% when the sample was preserved with formaldehyde (3%). Simultaneously, an enrichment of the shorter alkyl chain homologues (C7EO and C10EO) was observed. The losses of NPEO were from 45% (sample preserved by acidification or by addition of 3% of formaldehyde) to 85% (sample preserved with 1% of formaldehyde). Additionally, an increase in concentration of polyethylene glycols (PEGs) and formation of different acidic forms, such as monocarboxylated (MCPEGs) and dicarboxylated polyethylene glycols (DCPEGs) were observed. The stability of surfactants preconcentrated on SPE cartridges was studied as a function of storage time and storage conditions (room temperature, 4 degrees C and -20 degrees C). The results indicate that disposable SPE cartridges can be recommended for the stabilization of non-ionic surfactants and LAS. Storage at -20 degrees C is feasible for long periods (up to 3 months for ground water and up to 2 months for waste water), while storage at 4 C can be recommended for a maximum of 1 month. When cartridges were kept at -20 degrees C the losses of AEOs (n = 12, 13 and 14), preconcentrated from waste water, ranged from 17 to 29% (after 60 days) and other compounds suffered small losses (maximum of 14% for C13LAS). At room temperature, after 7 days, the losses were less than 11%, indicating that shipping of samples by mail can be done without any special requirements.     

Electronic spectrum and thermal decomposition of nickel(II) complex with bis(N-γ-pyridyl-4-phenylbenzamide-hydrazone)

The unit cell parameters and the space group of the investigated compound were determined by means of X-ray diffraction.Analysis of the diffusion-reflection spectra of the crystalline powder and the absorption spectra of its alcoholic solutions permitted identification and quantitative characterization of the absorption bands of the crystalline complex of NiL₂(ClO₄)₂·3H₂O.Application of differential-thermal analysis allowed determination of the mechanism of thermal decomposition of the compound. From these measurements, the expected configuration of the basic molecule was verified, involving determination of the number of non-coordinated water molecules.

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Zusammenfassung Mittels Röntgendiffraktionsmethoden wurden Gitterzellenkonstanten sowie die Raumgruppe der untersuchten Verbindung bestimmt. Durch Analyse der erhaltenen Diffusions-Reflexionsspektren von kristallinem Pulver und des Absorptionsspektrums einer alkoholischen Lösung der Verbindung war es möglich, die Absorptionsbanden des Kristallkomplexes NiL₂(ClO₄)₂·3H₂O zu identifizieren und quantitativ zu charakterisieren. Anwendung von Differentialthermoanalyse ermöglicht die Bestimmung des Mechanismus der Zersetzungsreaktion der Verbindung. Durch diese Messungen, einschliesslich der Bestimmung der Anzahl nichtkoordinierter Wassermoleküle, wurde die erwartete Konfiguration des Grundmoleküles überprüft.

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NiL₂(ClO₄)₂·₂, L-N-- -4- . L-N---4- . , , . . , .