Identification and colorimetric determination of Fe(CN)6b-3 ion with o-Dianisidine

A new method for the investigation and colorimetric determination of ferricyanide ions is described. The reagent used is a solution of o-dianisidine in aqueous acetone, which gives a red colour with [Fe(CN)^b0]₃ when the pH 2.8 Beer's law is obeyed up to dilutions of 1:2.10^b6(D=10^b-6.3) and when 210-mm Nessler test-tubes are used, up to dilutions of 1:5.10^b6(D=10^b-6.7. The qualitative investigation gives good results even when ion? of the first group of the usual analytical procedure for anions are present; the sensitivity is 1.1 5.10^b6(D=10^b-6.7.     

Originalarbeiten 133m Xe zur Markierung von Gasphasen bei technischen Tracerexperimenten

Bei technischen Tracerexperimenten bereitet die Markierung von Gasphasen Schwierigkeiten, wenn man auf Außenwandmessungen angewiesen ist, da die Auswahl an geeigneten Radionukliden bzw. radioaktiv markierten Verbindungen dann sehr beschrānkt ist. Eine gute Ergänzung des Radionuklidangebotes für den genannten Zweck bietet ^133mXe, Halbwertszeit 2,3 d, E_γ = 0,23 MeV (16%). ^133mXe erhält man mit guten Ausbeuten bei einer Reaktoraktivierung von natürlichem Xenon. Die Sälligungsaktivität fär ^133mXe beträgt bei einem Fluß von 5,0 μ 10¹³ n/cm²s 48,5 mCi/cm³ Xenon (unter Normalbedingungen). An Veweilzeitmessungen von Gasphasen in technischen Anlagen werden die Einsatzmöglichkeiten des ^133mXe dargestellt.     

Photocatalytic Nanoheterostructures and Chemically Bonded Junctions Made by Solution-Based Approaches

While single compound semiconductors were initially used for photocatalysis, combining two compounds to form a heterojunction significantly increases the photocatalysis performance. This review will outline how heterojunctions are superior, explain the different heterostructure architectures assembled from nanoparticles, and discuss the importance of achieving a large and quality contact in the junction, the heterojunction. Reference is made to methods for increasing the charge carrier performance and reducing recombination. Solution-based synthesis approaches, have been selected as the preferred route of manufacture, for the low cost scalability, and ability to combine a larger number of compounds. The main objective of this review article is to provide insight to the range of chemical solution-based methods for forming chemically bonded junction in nanoheterostructures for photocatalysis. Methods include chemical precipitation, impregnation, chemical bath deposition, hot injection, solvothermal, photo-deposition, electrochemical deposition, cation exchange and linker assisted assembly. The synthesis of different photocatalysts is addressed for each synthesis method. Solution synthesis is offered for coupling oxide semiconductors (i.e. TiO₂, ZnO, WO₃, Fe₂O₃, BiVO₄) with other oxides or metal chalcogenide quantum dots or metallic plasmonic nanoparticles.     

C–H⋅<Emphasis Type="Italic">s</Emphasis>O hydrogen bond networks in <Emphasis Type="Italic">E</Emphasis>- and Z-unsaturated esters of C-glycosides

Methyl E(Z)-4,7 anhydro-5-benzamido-6,8-di-O-benzoyl-2,3,5-trideoxy-d-allo-oct-2-enoate have been synthesized like intermediates and isolated as single crystals during the synthesis of pyrazole-related C nucleosides as synthetic product with cytotoxic activity.¹ Crystal structures of E(Z) isomers were determined by X-ray analysis. E isomer crystallizes in the triclinic crystal system, space group P1, a = 5.319(1) Å, b = 10.758(2) Å, c = 12.229(2) Å, α = 72.38(2)^∘, β = 89.97(2)^∘, γ = 87.07(2)^∘, D_x = 1.320 Mgm⁻³ and Z isomer in the orthorhombic crystal system, space group P2₁2₁2₁, a = 5.1297(13) Å, b = 19.667(5) Å, c = 25.871(6) Å, D_x = 1.348 Mgm⁻³. The molecular structure was solved by direct method on the basis of 2609 and 2727 unique reflections recorded at the temperature 293 K (E-isomer) and 173 K (Z-isomer) up to the final R-factor 0.0378 and 0.0435, respectively. C–H⋅sO contact networks were analyzed and the correlation established between the existence of the weak C–H⋅sO hydrogen bonds and the melting point of the single crystals.     

Nitric oxide binding and photodelivery based on ruthenium(II) complexes of 4-arylazo-3,5-dimethylpyrazole

Two fluorescent ligands, 3,5-dimethyl-4-(6'-sulfonylammonium-1'-azonaphthyl)pyrazole (dmpzn, 1) and 3,5-dimethyl-4-(4'-N,N'-dimethylaminoazophenyl)pyrazole (dmpza, 2) were obtained by condensation of ketoenolic derivatives with hydrazine. 1 and 2 formed the novel dinuclear complexes [(H(2)O)(3)ClRu(micro-L)(2)RuCl(H(2)O)(3)] (3 or 4) and [(H(2)O)(NO)Cl(2)Ru(micro-L)(2)RuCl(2)(NO)(H(2)O)] (6 or 7) (where L 1 = 2 or , respectively) which were characterized by IR, NMR and elemental analysis. The nitrosyl complexes were prepared by bubbling purified nitric oxide through methanol solutions of the corresponding ruthenium(II) chloroderivative or by reaction of the appropriate ligands with Ru(NO)Cl(3). Complexes 3 and 4 were found to bind NO, resulting in an increase in fluorescence. Ligand 1 also formed the mononuclear nitrosyl complex [Ru(NO)(bpy)(2)(dmpzn)]Cl(2) (8) which released NO in water at physiological pH and in the solid state as revealed by fluorescence and IR measurements, respectively.     

Wave-pinned filaments of scroll waves

Scroll waves are three-dimensional excitation patterns that rotate around one-dimensional space curves. Typically these filaments are closed loops or end at the system boundary. However, in excitable media with anomalous dispersion, filaments can be pinned to the wake of traveling wave pulses. This pinning is studied in experiments with the 1,4-cyclohexanedione Belousov-Zhabotinsky reaction and a three-variable reaction-diffusion model. We show that wave-pinned filaments are related to the coexistence of rotating and translating wave defects in two dimensions. Filament pinning causes a continuous expansion of the total filament length. It can be ended by annihilating the pinning pulse in a frontal wave collision. Following such an annihilation, the filament connects itself to the system boundary. Its postannihilation shape that is initially the exposed rim of the scroll wave unwinds continuously over numerous rotation periods.     

Scroll wave filaments terminate in the back of traveling fronts

Experiments with the 1,4-cyclohexanedione Belousov-Zhabotinsky reaction demonstrate that three-dimensional scroll waves can rotate around filaments that end in the wake of a traveling excitation pulse. The vortex structures nucleate during the collision of three nonrotating excitation pulses. The nucleation process and the wave-termination of filaments are direct consequences of the system's anomalous dispersion relation. Vortex filaments are found to expand with about twice the speed of their anchoring wave fronts. Filament expansion is accompanied by the build-up of phase differences in spiral rotation creating strongly twisted wave structures. Experiments employ optical tomography for the reconstruction of the three-dimensional wave patterns.     

On the field method in non-holonomic mechanics

This paper deals with the generalization of the field method to non-holonomic systems whose motion is subject to either non-linear constraints or those of a higher order, while their motion is modeled by the generalized Lagrange equations of the second kind. Two examples are given to illustrate the theory.The project supported by the Ministry of Science, Technologies and Development, Republic of Serbia (1874)     

Fluorescent labeling of a narrow polydispersity high molecular weight polystyrene

Narrow polydispersity polystyrene with a molecular weight of 1.03×10⁶ has been functionalized with anthracene groups using the metallocene technique. Side reactions such as chain coupling and bond scission can be limited by working in THF at –75°C. Gel permeation chromatography combined with on‐line viscometric, refractive index and fluorescence detection allows us to verify that degradation did not exceed 1 bond scission/180 000 monomer units. The degree of grafting increases with the reaction time but remains modest (< 5% after 7 h) at low temperature.     

Fluoridhaltige Gäste in Alumosilicaten: Tetrafluoroborate in dem Sodalithen Na8Al6Si6O24(BF4)2

In the course of investigations on optical properties resulting from the interaction of fluorides with alumosilicate host materials and rare earth guests, a well defined BF₄^– ion wasfound to be incorporated within the sodalite of composition Na₈Al₆Si₆O₂₄(BF₄)₂. The resulting cubic molecular structure, which was determined by Rietveld methods (space group P4 n, a = 906.91 pm, wRp = 0.045, Rp = 0.027), contains one anion in each sodalite cage and is, contrarily to expectations, thermally stable. NMR spectroscopic investigations indicated a fast rotatory motion of the BF₄^– tetrahedra at room temperature and agreed with the tetrahedral BF₄^– ions found in IR and Raman spectra. Preliminary attempts to obtain a luminescent material by incorporation of Eu³⁺ through aqueous ion exchange only yielded low rare earth concentrations, giving rise to characteristic red emission lines at 581 nm (⁵D₀ → ⁷F₁) and 615 nm (⁵D₀ → ⁷F₂) in a 1:2 intensity ratio. The material unexpectedly exhibited a strong broad band emission at 520 nm after calcination under Ar, which is attributed to the formation of an Eu²⁺ species. Further calcination under air partially reestablished the Eu³⁺ emission.