Sonochemical preparation of SbSeI gel

A novel sonochemical method for direct preparation of nanocrystalline antimony selenoiodide (SbSeI) has been established. The SbSeI gel was synthesized using elemental Sb, Se, and I in the presence of ethanol under ultrasonic irradiation (35 kHz, 2 W/cm²) at 50 °C for 2 h. The product was characterized by using techniques such as powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and optical diffuse reflection spectroscopy (DRS). The SEM and HRTEM investigations exhibit that the as-prepared samples are made up of large quantity nanowires with lateral dimensions of about 20–50 nm and lengths reaching up to several micrometers and single crystalline in nature.     

Electrical conduction in nanostructured carbon and carbon-metal films grown by supersonic cluster beam deposition

We have studied the electrical conduction in nanostructured carbon (ns-C) films produced by deposition of a supersonic beam of neutral carbon clusters. The d.c. conduction properties of these films have been measured in situ during the deposition process and ex situ as a function of the temperature in vacuum and in ambient of different gases (H₂, N₂, CH₄, He). The ns-C films exhibit an ohmic behavior with a room temperature resistivity in the range of 10⁷-10⁹ W{\rm\Omega} cm depending on the growth and storage conditions. Conductivity vs. temperature measured in vacuum in the range 290-400 K is characterized by activation energies in the range of 0.3-1.7 eV, the current response does not differ significantly in gas atmosphere. Nanocomposite carbon-metal films have been obtained by adding small amounts of metallorganic precursors containing molybdenum and cobalt during the formation of carbon clusters prior to deposition. The films are characterized by porous carbon networks containing small metal and metal carbide clusters. Electrical transport properties of these films have been studied as a function of temperature, gas pressure and relative humidity. In particular, the electrical conductivity of the sample produced with molybdenum showed to be much sensitive to changes in gas pressure and relative humidity, being characterised by fast and reversible responses.     

Activity coefficients of CaCl2 and MgCl2 in the presence of dipalmitoylphosphatidylcholine-phosphatidylinositol vesicles in aqueous media

Mean activity coefficients of CaCl₂ and MgCl₂ salts have been measured in the presence of phospholipid vesicles, by use of the EMF method with ion-exchange membrane electrodes, as a novel procedure for studying the direct interactions between electrolytes and phospholipid vesicles. Mixed lipid sonicated vesicles have been prepared from dipalmitoylphosphatidylcholine (DPPC)-phosphatidylinositol (PI) mixtures, covering a range of composition. The CaCl₂ and MgCl₂ concentration range studied was 0.01−0.001 mol l⁻¹. For both salts studied, the activity coefficients decrease linearly as the vesicle concentration in the suspension increases while the concentration of salt was kept constant. Maintaining a constant vesicle concentration, the decrease in the activity coefficients is more pronounced the more dilute the concentration of the salts. Quantitative differences were observed in the behaviour of both salts which are explained on the basis of a higher affinity of the Ca²⁺, compared with that of Mg²⁺ ions, to the vesicle surface. Using a simple model for the vesicle-salt systems, the number of cations specifically bound to the vesicles has been calculated. In view of the results it can be concluded that estimation of the activity coefficients of the salts is a useful method for the study of the interactions taking place in vesicle-salt systems.     

Effects of Lacticaseibacillus rhamnosus LOCK900 on Development of Volatile Compounds and Sensory Quality of Dry Fermented Sausages

Traditional dry fermented meat products are highly appreciated by consumers. A probiotic starter culture increases their attractiveness through sensory qualities and a potential health-promoting effect. The ability to scale the laboratory solution to industrial conditions is an additional scientific and practical value of a new way of using probiotics in the meat industry. The aim was to evaluate the influence of the probiotic starter culture Lacticaseibacillus rhamnosus LOCK900 on the development of volatile organic compounds and the sensory quality of dry fermented pork sausages during fermentation and refrigeration storage. The microbiological and sensory characteristic (QDA method) and volatile compound (gas chromatography coupled with mass spectrometry: GC–MS) were evaluated. The number of LOCK900 cells during 12 weeks of storage remained above 6 log CFU g⁻¹, making this product a functional food. The addition of probiotic LOCK900 increased the levels of acidic volatile compounds, aldehydes, and esters, which, combined with the additives and spices used, had a positive effect on the sensory properties of ripening sausages. The sausages with LOCK900 were characterised by positive sensory features, and their overall quality remained high during storage and did not differ from that of the control sausages.     

Palladium-catalyzed synthesis of coumarin

A palladium-catalyzed synthesis of coumarin, involving ring formation from o-iodophenol, norbornadiene, and carbon monoxide, followed by elimination of cyclopentadiene, is described, and contrasted with a new synthesis of aurone, based on the reaction of iodophenol, carbon monoxide, and phenylacetylene.     

Similarity and fractality in the modelling of roughness by a multilevel profile with hierarchical structure

Some modern scaling and fractal approaches to the characterization of surface roughness are under consideration. A new mathematical model of a multilevel profile suitable for flexible simulation of roughness is presented as a development from these approaches. The iterative construction of the model is described. It is shown that the profile is a hierarchical structure with self-affine and fractal features. Its geometrical properties are studied both analytically and numerically, and some of them are proved to be of the renormalization type. The profile contour length can be finite or infinite depending on the chosen values of the structural parameters. Some characteristics including the bearing curve and the upper volume function of the profile and the corresponding prestructures are calculated.     

A study of the mechanism of action of aromatic thiols on carotenoid pigments

Aromatic thiols are used widely to bleach carotenoid plant pigments present in natural rubber latex in trace quantities, in the manufacture of white latex crepe rubber. If this is not done these pigments impart a yellow colour to the crepe, thereby lowering its grade. The bleaching reaction between carotenoid pigments and aromatic thiols is known to occur in the presence of at least diffuse daylight. In this mechanistic study it was observed that the aromatic thiols have no action on unoxidised carotene. However, the peroxy radicals formed on the carotene molecule undergoing autoxidation under the influence of uv light initiate radical formation on the thiol, which is difficult to split by other means. These radicals then combine with the unsaturated chains of both carotene and cartenoids in the system, thereby disrupting the double bond conjugation and making the compounds colourless.     

Influence of chromophore dipole moments in parameterts of organic light emitting devices based on phenyl and methyl modified pyrazoloquinoline

Absorption, photo- and electroluminescence spectra of some trityl substituted 1H-pyrazolo[3,4-b]quinolines derivatives (methyl- and phenyl substituted) and fabrication of the single layered organic light emitting diodes are reported. The bulky trityl substituent was introduced to prevent aggregation and crystallization of the dopant in polymer matrix. Role of ground state dipole moments in the observed red Stokes shift, electroluminescent features and photocarrier transport is explored. The maximally achieved brightness about 50 Cd/m² is observed in the spectral range extending from 443 nm up to 462 nm. The voltage threshold was varied from 7.8 V up to 10 V. The brightness-current dependences show an existence of at least two types of carrier injections.     

Measurement of the production cross-section of positive pions in p–Al collisions at 12.9 GeV/c

A precision measurement of the double-differential production cross-section, $d^2{\sigma }^{{\pi }^{+}}/dpd\Omega$, for pions of positive charge, performed in the HARP experiment is presented. The incident particles are protons of $12.9\text{ GeV}/c$ momentum impinging on an aluminium target of 5% nuclear interaction length. The measurement of this cross-section has a direct application to the calculation of the neutrino flux of the K2K experiment. After cuts, 210 000 secondary tracks reconstructed in the forward spectrometer were used in this analysis. The results are given for secondaries within a momentum range from 0.75 to 6.5 GeV/c, and within an angular range from 30 mrad to 210 mrad. The absolute normalization was performed using prescaled beam triggers counting protons on target. The overall scale of the cross-section is known to better than 6%, while the average point-to-point error is 8.2%.     

Inactivation of Staphylococcus aureus and native microflora in human milk by high pressure processing

The storage of unpreserved food, including breast milk, is associated with the growth of microorganisms, including pathogenic bacteria. It is therefore necessary to use suitable processes to eliminate pathogenic microorganisms and reduce the total microbial count in order to ensure product safety for consumers. In the present study, samples of milk obtained from volunteers donating to the human milk bank were artificially contaminated with Staphylococcus aureus ATCC 6538. This bacteria was the model microorganism of choice, being relatively resistant to high pressure as well as posing the most serious risk to infant health. The results obtained show that high pressure processing can reduce the count of S. aureus by about 5?log units at 4°C and about 8?log units at 50°C, and totally eliminate Enterobacteriaceae after 5?min of treatment, and result in a total microbial count reduction after 10?min treatment at 500?MPa at 20°C and 50°C. This suggests the possibility of this technology being applied to ensure the adequate safety and quality of human breast milk in human milk banks.