The effect of catalyst preparation on the performance of magnesium fluoride supported ruthenium

The effect of different ruthenium precursors on the structure and catalytic properties of the Ru/MgF₂ system was studied with such methods as IR, XPS, EPR and catalytic test reactions. The adsorption of probe molecules (CO and O₂) revealed a greater ability to transfer an electron from ruthenium in the case of samples obtained from Ru₃(CO)₁₂ than in the case of samples obtained from RuCl₃. Besides, metallic crystallites of different size were obtained depending on the precursor used. Namely, the average cluster size was 1.5 times smaller for carbonyl samples in comparison with chloride ones. Both series of preparations were active in redox or acid-base reactions. The activities of the carbonyl samples were higher than those of the chloride catalysts, particularly in reactions that require the presence of acid centers. This revised version was published online in July 2006 with corrections to the Cover Date.     

Quality assessment for a visual and automatic license plate recognition

Video transmission and analysis is often utilized in applications outside of the entertainment sector, and generally speaking this class of video is used to perform specific tasks. Examples of these applications include security and public safety. The Quality of Experience (QoE) concept for video content used for entertainment differs significantly from the QoE of surveillance video used for recognition tasks. This is because, in the latter case, the subjective satisfaction of the user depends on achieving a given functionality. Recognizing the growing importance of video in delivering a range of public safety services, we focused on developing critical quality thresholds in license plate recognition tasks based on videos streamed in constrained networking conditions. Since the number of surveillance cameras is still growing it is obvious that automatic systems will be used to do the tasks. Therefore, the presented research includes also analysis of automatic recognition algorithms.     

Isolation and amino acid sequence of a serine proteinase inhibitor from common flax (Linum usitatissimum) seeds

LUTI (Linum usitatissimum trypsin inhibitor), a member of the potato inhibitor I family, has been isolated from seeds of flax by ethanol fractionation, ion exchange chromatography on CM-Sephadex C-25, affinity purification on immobilized methylchymotrypsin (alpha-chymotrypsin in which His57 has been converted to 3-methylhistidine) in the presence of 5M NaCl, and finally by reversed-phase HPLC. The 7655 Da inhibitor consists of a single polypeptide chain of 69 residues with one disulfide bridge. The molecule is acetylated at the N terminus. Its primary structure has been determined after limited proteolysis of the native molecule with trypsin at the reactive site, cleavage with cyanogen bromide or arginyl endopeptidase (Arg-gingipain), and alcoholytic deacetylation of the N-terminally blocked serine. The association constants (K(a)) of LUTI with bovine beta-trypsin and alpha-chymotrypsin are 3.58x10(10) M(-1) and 5.02x10(5) M(-1), respectively. High NaCl concentration (3M) increased the association constant of LUTI with alpha-chymotrypsin to 6.64x10(7) M(-1). To our knowledge, LUTI is the first serine-proteinase-type inhibitor isolated from a plant of the Linaceae family.     

Defect structure and chemical diffusion in nickel sulfide β-Ni3S2

The chemical composition, defect structure, and diffusion in nickel sulfide -Ni₃S₂ have been investigated in H₂S-H₂ mixtures containing between 1 and 65% H₂S between 560 and 700°C. Gravimetric, density, and X-ray studies were carried out. In the thermodynamically stable compound the ratio of Ni/S varied between 1.3 and 1.75. The X-ray examination showed a step change in the lattice parameter at the Ni/S ratio 1.4. A linear dependence of the density values (between 5.5 and 6.2 g/cm³) on the composition was observed. On the basis of the chemical composition and density measurements the number of nickel and sulfur atoms in 1 cm³ were determined. It has been shown that the Ni₃S₂ phase is defected in both anion and cation sublattices and that its chemical formula may be described as follows: Ni_3±yS_2x, where y 2x. It has been found that in the mixture containing 10% H₂S the process of defect formation is determined by their diffusion in the sulfide. The temperature dependence of the diffusion coefficient is described by the equation D = 13.15 exp(-30,000/RT) cm²/sec. No dependence of D on the sulfur partial pressure was observed, but this may be due to the relatively large uncertainties in the measurement of the diffusion coefficients.     

Kinetics of copper sulfidation at temperatures 570–1123 K

The kinetics of copper sulfidation have been studied as a function of temperature (570–1120 K) by the use of the modified Wagner's pellet method. It has been found that sulfidation follows a parabolic rate law with different activation energies in the low- and high-temperature ranges: $$k_{p}^{'} = 10.2 exp - (70 \pm 4)[kJ/mole]/RT (570 - 780 K)$$ and $$k_{p}^{'} = 1.69 \times 10^{ - 3} exp - (13 \pm 1.0)[kJ/mole]/RT (780 - 1120 K)$$ Using thermodynamic data as well as interfacial chemical potentials and ionic conductivity, the parabolic rate constants of sulfidation of copper have been calculated with good agreement with experimental results. Parabolic rate constants of sulfidation have been used to calculate average self-diffusion coefficients of copper in Cu₂S, the temperature dependence of which is as follows: $$\bar D_{Cu} = 8.76 \times 10^{ - 4} exp - (22.4 \pm 1)[kJ/mole]/RT$$      

A two‐level detector of short‐term unique changes in time series based on a similarity method

In the paper, a novel two‐level algorithm of time‐series change detection is presented. In the first level, to identify non‐stationary sequences in a processed signal, preliminary detection of events is performed with a short‐term prediction comparison. In the second stage, to confirm the changes detected in the first level, a similarity method aimed at identification of unique changes is employed. The detection of changes in a non‐stationary time series is discussed, implemented algorithms are described and the results produced on a sample four financial time series are shown. General conditions for implementing the proposed algorithm as an immune‐like event detector are discussed.