Softening during and after the hot deformation of the AISI 321 steel with respect to practical applications

The softening processes during and after the hot deformation (850–1180 C) in AISI 321 stainless steel were studied with respect to true strains _D and true strain rates . The analysis of deformation curves indicates the occurrence of dynamic recrystallization for values of Zener-Hollomon parameterZ10¹⁵ s^–1. The retardation of static recrystallization by fine Ti(N, C) precipitates is documented by microstructure studies and by variations of annealing conditions.     

Recovery and recrystallization in AISI 321 steel under static conditions

Static softening of AISI 321 steel after cold and hot deformation characterizing the industrial thermomechanical treatment was studied by means of tensile tests and TEM. The deformation temperature, the strain and the grain size were the main parameters determining the final softening. The results can be applied for optimization of the solution annealing.     

New Luminescent Lanthanide Tetrakis-Complexes NEt4[LnL4] Based on Dimethyl-N-Benzoylamidophosphate

New lanthanide dimethyl-N-benzoylamidophosphate (HL) based tetrakis-complexes NEt₄[LnL₄] (Ln³⁺=La, Nd, Sm, Eu, Gd, Tb, Dy) are reported. The complexes are characterized by means of NMR, IR, absorption, and luminescent spectroscopy as well as by elemental, X-Ray, and thermal gravimetric analyses. The phenyl groups of the four ligands of the complex anion are directed towards one side, while the methoxy groups are directed in the opposite side, which makes the complexes under consideration structurally similar to calixarenes. The effect of changing the alkali metal counterion to the organic cation NEt₄⁺ on the structure and properties of the tetrakis-complex [LnL4]^- is analyzed. The complexes exhibit bright characteristic for respective lanthanides luminescence. Rather high intensity of the band of ⁵D₀→⁷F₄ transition, observed in the luminescence spectrum of NEt₄[EuL₄], is discussed based on theoretical calculations.     

Facile Synthesis of Bis(crown ether)benzils: Prospective Building Blocks for Metal Ion Sensors

A new facile synthetic route to benzils containing fragments of 12-crown-4, 15-crown-5, and 18-crown-6 by oxidation of corresponding stilbenes was developed. The first representative of a new family of fluorescent sensors was obtained by reaction of bis(15-crown-5)benzil with o-phenylenediamine. The latter exhibits great fluorescence enhancement upon association with K⁺ and Rb⁺ compared to Na⁺ and Cs⁺.     

On the particle hardening in Cu-Cd alloy single crystals

The transmission electron microscopy of Cu-Cd single crystals deformed previously was performed to explain the hardening effect measured. The increment of the critical resolved shear stress is explained by the size misfit effect of the observed particles.     

Coordination compounds of neodymium,samarium, and europium with acyldihydrazones of imino-, oxo-, and thiodiacetic acids and 3-methyl-1-phenyl-4-formylpyrazol-5-one

The coordination compounds of neodymium(III), samarium(III), and europium(III) with the acyldihydrazones of imino-, oxo-, and thiodiacetic acids and 3-methyl-1-phenyl-4-formylpyrazol-5-one were synthesized and studied. According to X-ray diffraction data, the complexes are binuclear and the lanthanide cations are linked by three binucleating ligands. The coordination polyhedra have a three-cap triangular prism geometry, the prism bases being formed by oxygen atoms and the vertices being occupied by the imine nitrogen atoms. Solid Nd(III) and Sm(III) complexes show intense luminescence in the spectral regions characteristic of these cations. Europium(III) complexes are liminescence-inactive due to the low efficiency of excitation energy transfer to the resonance levels of the central atom.     

Boron-chelate assisted synthesis of new bipyrazole derivatives

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Study of the nuclear periphery with Antiprotons

In the experiments of the PS209 collaboration at the Low Energy Antiproton Ring LEAR at CERN two methods were applied to study the nuclear periphery: first the yields of residual nuclei with mass number A — 1 were determined with radiochemical methods, and secondly the widths and shifts of the last observable transitions in antiprotonic atoms were measured with Ge detectors. The ratio of yields after annihilation for nuclei with one neutron missing to those with one proton missing from the target nucleus was found to depend strongly on the binding energy of the most loosely bound neutron of the target nucleus. The values were in astonishingly good agreement with a rather simple model for the proton and neutron density distribution devised by Gambhir et al. Furthermore the normalized yield ratio stays constant up to a relative neutron excess of about 0.15 and afterwards rises steeply. Widths for in total 62 x-ray Unes from antiprotonic atoms were compared with the results of calculations of Batty et al. The agreement is reasonable on a semiquantitative basis, but improvements are desirable. For a number of nuclei the differences between the diffuseness values for the proton and neutron distributions were determined directly from the x-ray-line intensity and width data. The root-mean-square radii for the neutron and proton distributions may be derived from these results. The experimental data for four tin isotopes are in reasonable agreement with the experiments of Krasznahorkay et al., but lower than theory predicts.     

Polarographic determination of thiabendazole

Summary Polarographic Determination of Thiabendazole Thiabendazole is used as a fungistat on citrus fruit to protect it from decay.In order to work out a polarographic determination the electrochemical behaviour of thiabendazole was investigated by sampledd c polarography and differential pulse polarography. Thiabendazole shows one wave or peak in the polarogram, when a short drop time (0.4 s) is used. Detection is most sensitive at pH 8. The current measured is proportional to the concentration. The detection limit is 0.5 ppm.By evaluating further experimental data it was possible to conclude, that mercury is first oxidised. Thereby two electrons are exchanged. Then mercury(II) ions formed in this way react with two molecules thiabendazole. Two protons are involved in this chemical process.Applying drop times greater than 0.4 s and concentrations higher than 1.5·10^–4 M a polarogram with two peaks is formed. This is due to the adsorption of the reaction product.For quantitative determination several citrus fruits were peeled and the peels were extracted with ethylacetate. After removing interfering substances by shaking with sodium hydroxide solution, thiabendazole was extracted by diluted hydrochloric acid and quantitatively determined by differential pulse polarography. The recovery of thiabendazole is 70.0% with a relative standard deviation of 2.9%. For all samples investigated the thiabendazole concentrations were below the permitted value.Cordially dedicated to Univ.-Prof. Dr. Dr. h. c. K. Kratzl on the occasion of his 70th birthday.