Internal friction in cd+zn alloy single crystals

Internal friction measurements were used for the examination of Cd + Zn alloy single crystals. It was established that the interaction energy between solute Zn atoms and dislocations in basal planes is 0·12 eV.The authors thank Dr. P.Luká, CSc., for valuable discussions.     

Field and temperature dependence of magnetization of U3P4

Conclusions We conclude that the occurrence of a maximum in the magnetization versus temperature curve observed under certain circumstances on U₃P₄ is not connected with its intrinsic magnetic structure, but substantially depends on the form in which the material is studied (polycrystalline powder, single crystal, single crystal powders with various dimensions of grains). This phenomenon seems to be affected by quenching of the state from the region of low anisotropy at higher temperature in the small particles with a strong tendency to single domain behaviour and thus it may be a consequence of rotation magnetization process in the fields relatively small for U₃P₄. The assertion about transitions between magnetic ordering, sometimes proposed in the literature on the basis of observed anomalies in the temperature course of magnetization without simultaneous confirmation by neutron diffraction, should be accepted with some reservation, especially in the case of simple uranium compounds. However, another situation arises for pseudobinary alloys of ferro- and antiferromagnetic components (e.g. UP_0·75S_0·25) where such transitions were confirmed both by magnetic methods and by neutron diffraction studies [13].The authors would like to express their thanks to Ing. A.Meovský for careful preparation of samples.     

On the character of local electric fields in amorphous semiconductors

On the basis of the agreement of calculated and measured parameters of some amorphous semiconductors, an argument is stated in favour of the central-symmetric type of random local electric fields. A possible mechanism of the transport of electrons is discussed.     

The relation between deep trapping levels and the structure of Se layers

Using electron microscopy methods it has been determined that there are numerous crystalline inclusions in evaporated layers of amorphous selenium. The density, dimensions, modification and distribution in the cross section of a layer are essentially dependent upon the method of layer preparation. The maximum micro-inclusion density is observed in layers evaporated at a substrate temperature (t_s) between 8 to 30°C. These layers also possess crystallites of monoclinic modification. In layers evaporated at t_s ? 50°C inclusions of trigonal modification prevail.The parameters of the deep trapping levels for holes and electrons have been determined from photodischarge kinetics. The origin of these levels is found to be related to the phase transition. The hole traps are caused by the crystalline formation of trigonal modification, and the electron traps by crystallites of monoclinic modification.     

A study into Stille cross‐coupling reaction mediated by palladium catalysts deposited over siliceous supports bearing N‐donor groups at the surface

Mesoporous molecular sieve SBA‐15 and conventional silica gel were grafted with 3‐[2‐(diethylamino)ethylamino]propyl groups and used as supports for the preparation of deposited palladium catalysts, which were subsequently evaluated in Stille cross‐coupling reaction of aryl bromides. The highest conversions were achieved with the metal‐saturated catalyst resulting from the modified SBA‐15. Influence of various reaction parameters (solvent, additive, temperature, etc.) on the overall yield and selectivity was studied. Copyright © 2013 John Wiley & Sons, Ltd.     

Electrolyte system strategies for anionic isotachophoresis with electrospray‐ionization mass‐spectrometric detection. 1. Regular isotachophoresis and free‐acid isotachophoresis

The subject of this work is the definition of a simple model based on general ITP theory that allows describing and predicting the behavior of ITP systems compatible with ESI‐MS detection. The model is exemplified by anionic ITP of weak acids that represent an interesting potential application field of ITP‐ESI‐MS. Suitable ESI‐compatible electrolyte systems of very simple composition are proposed including a special free‐acid ITP arrangement. The properties of these systems are discussed using illustrative diagrams of their stacking windows. The use of anionic ITP‐ESI‐MS in negative‐ion ESI mode is reported for the first time and its suitability for sensitive trace analysis is demonstrated. The presented ITP‐ESI‐MS application example comprises a free‐acid ITP system formed of formic and propionic acids and direct injection analysis of ibuprofen and diclofenac in waters with quantitation limits of the order 10^?10 M.     

Influence of ion bombardment on growth and properties of PLD created DLC films

A hybrid PLD system with ion bombardment of films was developed. Growing DLC films were modified during the laser deposition (10 J?cm^?2) by argon ions with energy in the range from 40 eV to 210 eV and cathode current of 0.15 A and 0.5 A. The content of sp² “graphitic” and sp³ “diamond” bonds was measured using XPS. Sp³ bonds changed from 60 % to 81 %. We found the highest sp³ content for energy of 40 eV. Hardness (and reduced Young’s modulus) were determined by nanoindentation and reached 49 GPa (277 GPa). Film adhesion was studied using the scratch test and was up to 14 N for titanium substrates. Relations among deposition conditions and measured properties are presented.     

Studium der Abbaugeschwindigkeit der Oberfläche von markierten festen Stoffen zwecks reaktionskinetischer Untersuchungen, 2. Mitt.: Anwendung von mittels Diffusionstechnik hergestellten Trägern

Eine der oft angewandten Möglichkeiten der Markierung fester Träger mit gasförmigen Tracern ist die Diffusionstechnik. Die mit dieser Technik hergestellten Träger wurden zu reaktionskinetischen und analytischen Bestimmungen herangezogen. Im vorliegenden Artikel werden die Grenzen und die Möglichkeiten der Anwendung dieser Träger anhand der in der früheren Mitteilung abgeleiteten allgemeinen Erwägungen theoretisch begründet.     

Interaction Products of 12·5 Deuterons with Molybdenum and their Isolation Possibilities from Worn-out Cyclotron Parts

Using chemical separations and radiometric measurements medium-half-life irradiation products of molybdenum with 12.5 MeV deuterons were determined (⁹⁰Nb, ⁹²Nb, ^95mNb, ⁹⁵Nb, ⁹⁶Nb, ⁹⁹Mo, ^95mTc, ⁹⁶Tc, ^99mTc) as well as thick target yields for some of them: ⁹²Nb (0.22 μCi/μAh), ⁹⁵Nb(0.05 μCi/μAh), ⁹⁹Mo (64 μCi/μAh), ^95mTc(0.76 μCi/μAh), ⁹⁶Tc((62.5 μCi/μAh). Moreover isolation possibiities of radioactive preparations from removed worn-cut molybdenum parts of the U-120 cycletron are discussed.     

Advection of a passive vector field by the Gaussian velocity field with finite correlations in time

Using the field theoretic renormalization group technique the model of a passive vector field advected by an incompressible turbulent flow is investigated up to the second order of the perturbation theory (two-loop approximation). The turbulent environment is given by statistical fluctuations of the velocity field that has a Gaussian distribution with zero mean and defined noise with finite correlations in time. Two-loop analysis of all possible scaling regimes in general d-dimensional space is done in the plane of exponents ? ? η, where ? characterizes the energy spectrum of the velocity field in the inertial range E ∝ k ^{1 ? 2ε}, and η is related to the correlation time at the wave number k which is scaled as k ^{?2 + η}. It is shown that the scaling regimes of the present model of vector advection have essentially different properties than the scaling regimes of the corresponding model of passively advected scalar quantity. The results demonstrate the fact that within the present model of passively advected vector field the internal tensor structure of the advected field can have nontrivial impact on the diffusion processes deep inside in the inertial interval of given turbulent flow.