Thermal Expansion,Electrical Resistivity,and Spreading Area of Sn-Zn-In Alloys

Thermal expansion and electrical resistivity of alloys based on Sn-Zn eutectic with 0.5, 1.0, 1.5, and 4.0 wt.% additions of In were studied. Thermal expansion measurements were performed using thermomechanical analysis tester over 223-373 K temperature range. Electrical resistivity measurements were performed with four-probe method over 298-423 K temperature range. The electrical resistivity of alloys increases linearly with temperature and concentration of In; also coefficient of thermal expansion of the studied alloys increases with In concentration. Scanning electron microscopy revealed simple eutectic microstructure with In dissolved in Sn-rich matrix. The results obtained were compared with the available literature data. Spreading tests on Cu of Sn-8.8Zn alloys with 0.5, 1.0, and 1.5 at.% of In were performed. Wetting tests were performed at 250 °C, by sessile drop method, by means of flux, and wetting times were 3, 8, 15, 30, and 60 min. In general, no clear effect of wetting time on spreading was observed.     

Origin of Violet‐Blue Emission in Ti‐Doped Gahnite

ZnAl₂O₄ doped with Ti⁴⁺ (2%) was synthesized by the hydrothermal method at 220°C at pressure of 25 bars. An average grain size of the as‐prepared sample was 3 nm, the samples with biggest grain size were obtained after annealing at 300°C, 500°C, 600°C, 700°C, and 900°C, diameter of the latter was about 33 nm. IR spectroscopy indicated that ZnAl₂O₄ was partially inverted. The degree of the inversion decreases with increase in the annealing temperature but increases with increasing Ti⁴⁺ content. Absorption and emission spectra as well as emission decay profiles were recorded at 300 and 77 K. The observed spectra are due to charge‐transfer O^2??Ti⁴⁺ transitions. Color of the emission depends on the nanocrystal size and with increase in its diameter changes from violet to blue, accordingly the absorption bands exhibit redshift. The calculations based on Density Functional Theory confirmed the experimental results. 3d electrons of titanium ions form the bottom of the ZnAl₂O₄:Ti⁴⁺ conduction band, oxygen, aluminum or zinc vacancies create additional levels in the gahnite energy band gap. It was also found that in ZnAl₂O₄ aluminum or zinc vacancy induces magnetism with relatively high magnetic moment close to 1 μ_B per vacancy.     

The electroreduction of alkyl iodides and polyiodides: The kinetic model of EC(C)E and ECE-EC(C)E mechanisms with included transfer coefficient variability

The cyclic voltammetry electroreduction of seven alkyl iodides was investigated in 0.3 M TBAP/DMF on glassy carbon electrode. The influence of carbon chain length and the number of iodine atoms in the molecule was examined. The two-electron reductive cleavage with iodine elimination was numerically resolved into one-electron consecutive steps. The mechanism of the process was discussed applying the mathematical EC(C)E and ECE-EC(C)E kinetic models with included transfer coefficient variability for one stage electroreduction of RI and two stage electroreduction of RI₂, respectively. For electroreduction of diiodomethane the discrimination of elementary alpha parameter between two reduction stages was determined.     

k‐sample median test for vague data

Classical statistical tests may be sensitive to violations of the fundamental model assumptions inherent in the derivation and construction of these tests. It is obvious that such violations are much more probable in the presence of vague data. Thus nonparametric tests seem to be promising statistical tools. In the present paper, a distribution‐free statistical test for the so‐called “many‐one problem” with vague data is suggested. This test is a generalization of the k‐sample median test. In our approach, we utilize the necessity index of strict dominance, suggested by Dubois and Prade. © 2009 Wiley Periodicals, Inc.     

Synthesis,Enzymatic Evaluation,and Docking Studies of Fluorogenic Caspase 8 Tetrapeptide Substrates

The synthesis, enzymatic evaluation, and molecular modeling studies of new fluorogenic tetrapeptide‐based substrates selective for caspase 8, having the general structure Ac‐IETD–AXX, are described. Various fluorescent reporter groups (AXX), i.e., 3‐ and 4‐substituted coumarins and quinolin‐2(1H)‐ones were synthesized by von Pechmann condensation. They were subsequently coupled with the caspase‐8‐selective tetrapeptide Ac‐IETD‐OH under newly developed synthetic conditions to give the desired substrates in good yields and in high enantiomeric purity. Based on K_M and V_max values, the new compounds proved to be excellent substrates for recombinant human caspase 8. In contrast, the K_M values for the same compounds as substrates for human caspase 3 were approximately 10–20‐fold higher. Molecular modeling studies based on the X‐ray crystal structures of both human caspases 3 and 8 revealed that there is sufficient room within both active sites to accommodate substrates with moderately bulky substituents in the 3‐ and 4‐positions of the fluorogenic coumarins and quinolin‐2(1H)‐ones. Automated docking of the substrates into the active sites of both human caspases 3 and 8 with the program AutoDock 3 gave structures similar to the published crystallographic structures for the same tetrapeptide bound to caspase 8 in the form of an irreversible inhibitor. The calculated binding energies for the new substrates to either caspase 3 or 8 showed little difference between the substrates, consistent with the K_M data. In addition, the calculated binding energies (ΔG) to caspase 8 were considerably more negative than those to caspase 3, also consistent with the K_M data. A possible molecular interaction that might explain the selectivity of the IETD tetrapeptide motif for caspase 8 over caspase 3 is discussed.     

Simultaneous handover scheme for IEEE 802.11 WLANs with IEEE 802.21 triggers

Handover performance in wireless networks is important, especially nowadays, when multimedia services are becoming increasingly available over the wireless devices. However, users expect uncompromised mobility when using the service. Thus, the support of multimedia services is not possible if handover is inefficient. At the same time it is clear that a strict separation between IP Layer and the Link Layer results in built-in sources of delay. The paper discusses the IEEE 802.11 and Mobile IPv4 handover performance in practical scenarios. We introduce a new simultaneous handover scheme with IEEE 802.21 triggers. In order to verify the handover performance, simulation experiments have been conducted, whose results are also presented and discussed.     

A comparison of the multistep consecutive reduction mode with the multicomponent system reduction mode in cyclic voltammetry

The multistep consecutive ECE-ECE reduction process A(e)-->B(k(f2))-->C(e)-->D(e)-->E(k(f2))-->F(e)-->G has been compared with reduction in multicomponent system A(e)-->B, C(e)-->D, D(e)-->E, F(e)-->G. A simple method of transformation has been devised to disclose the subtle structure of the complex cyclic voltammetry (CV) responses and illustrated by the ECE-ECE process modeled earlier. The method can be applied to any multi-electron CV experimental curve for which a numerical modeling has been done. Electroreduction processes similar to those considered here are often met in practice. An attempt of unification of consecutive electroreduction and electroreduction of multicomponent system has been made. Interrelation between research and analytical voltammetry aspects of the problem is also discussed.     

AdROSA—Adaptive personalization of web advertising

One of the greatest and most recent challenges for online advertising is the use of adaptive personalization at the same time that the Internet continues to grow as a global market. Most existing solutions to online advertising placement are based on demographic targeting or on information gained directly from the user. The AdROSA system for automatic web banner personalization, which integrates web usage and content mining techniques to reduce user input and to respect users’ privacy, is presented in the paper. Furthermore, certain advertising policies, important factors for both publishers and advertisers, are taken into consideration. The integration of all the relevant information is accomplished in one vector space to enable online and fully personalized advertising.