Structure of Disodium Dimolybdate Synthesized Using Thermodynamically Stable Molybdenum (VI) Oxide Clusters as Precursors

The structure of disodium dimolybdate (Na₂Mo₂O₇) synthesized by a low-temperature method in the process of ultrasonic spray pyrolysis using acidified aqueous solutions of thermodynamically stable molybdenum (VI) oxide clusters as a precursor was refined down to an R -factor of 7%. The refinement of the diffraction data showed that Na₂Mo₂O₇ powder synthesized at 300°C belongs to the base-centered orthorhombic type of structure with a space group of Cmca (no. 64). It was found that the basic units of the octahedral MoO₆ precursor complexes exist in the structure of Na₂Mo₂O₇. Tetrahedral MoO₄ building units that coexist together with octahedral units in the structure of Na₂Mo₂O₇ are most likely developed by the termination of weak octahedral bonds and by the placement of the molybdenum atom in the center of the tetrahedra.     

Cobalt-chrome activation of the nickel electrodes for the HER in alkaline water electrolysis – Part II

Catalyst based on cobalt and chrome was investigated as cathode material for hydrogen production process via water electrolysis. Electrocatalytic efficiency of proposed system was studied using quasi-potentiostatic, galvanostatic and impedance spectroscopy techniques of the catalyst obtained by in situ electrodeposition in an alkaline, 6 M KOH, electrolyser. In accordance to our previous studies, synergetic effect of cobalt complex and chrome salt is observed, with its maximum at high temperatures and for high current densities (industrial conditions). The Tafel slopes were found to be around 120 mV and exchange current densities in the range of 10⁻³ mA cm⁻² up to 10⁻² mA cm⁻². Results are presented to show the Tafel slopes, the exchange current densities, the apparent energy of activation and the apparent electrochemical surface of in situ formed Co–Cr catalyst. This study shows that catalytic performance of Co–Cr was achieved not only from the increase of the real surface area of electrodes, but also from the true catalytic effect.     

Reduction of polycyclic aromatic hydrocarbons in common carp meat smoked in traditional conditions

Common carp meat was smoked in traditional conditions without filter and with zeolite, granular activated carbon, and gravel filters. The aim of this study was to determine the influence of using different filters in traditional smoking conditions on 16 polycyclic aromatic hydrocarbons from the Environmental Protection Agency list (16 US-EPA PAHs). Determination and quantification of PAHs were performed by gas chromatography–mass spectrometry (GC-MS). According to the obtained results, all examined samples of common carp meat smoked in traditional conditions were safe for consumers regarding to the European Commission Regulation on PAH content. After statistical analysis, the zeolite filter appeared to be the best one based on food safety of traditional production of smoked common carp meat. Application of any of these filters to produce smoked common carp meat in traditional conditions resulted in a safer product, as lower levels of PAHs were obtained.     

Digestibility and allergenicity assessment of enzymatically crosslinked β‐casein

Crosslinking enzymes are frequently used in bioprocessing of dairy products. The aim of this study was to examine the effects of enzymatic crosslinking on IgE binding, allergenicity and digestion stability of β‐casein (CN). β‐CN was crosslinked by transglutaminase, tyrosinase, mushroom tyrosinase/caffeic acid and laccase/caffeic acid. The IgE binding to β‐CN was compared in vitro by CAP inhibition assay, ELISA inhibition as well as ex vivo by basophil activation assay. Crosslinked CNs were digested by simulated gastric fluid for 15 and 60 min and obtained digests analyzed for their ability to inhibit IgE binding by CAP inhibition assay and SDS‐PAGE. The ability of crosslinked CNs to activate basophils was significantly reduced in seven patients in the case of CN crosslinked by laccase and moderately reduced in the case of tyrosinase/caffeic acid crosslinked CN (in two cow's milk allergy patients tested with different allergen concentrations). The response to various crosslinked CNs differed individually among patients' sera tested by ELISA inhibition assay. The presence of caffeic acid hampered digestion by pepsin, and this effect was most pronounced for the tyrosinase/caffeic acid crosslinked CN. The laccase/caffeic acid and mushroom tyrosinase/caffeic acid had the highest potential in mitigating IgE binding and allergenicity of the β‐CN out of all investigated enzymes. The presence of a small phenolic compound also increased digestion stability of β‐CN.     

Insights into proteolytic processing of the major peanut allergen Ara h 2 by endogenous peanut proteases

BACKGROUND: The major peanut allergens are Ara h 1, Ara h 2 and Ara h 6. Proteolytic processing has been shown to be required for the maturation process of Ara h 6. The aim of this study was to examine whether Ara h 2 undergoes proteolytic processing and, if so, whether proteolytic processing influences its ability to bind human immunoglobulin E (IgE). RESULTS: Ara h 2 isolated from peanut extract under conditions of protease inhibition revealed a single additional peak for its two known isoforms (Ara h 2.01 and Ara h 2.02), corresponding to a C‐terminally truncated form lacking a dipeptide (RY). Ara h 2 isolated in the absence of protease inhibition, however, yielded two additional peaks, identified as C‐terminally truncated forms lacking either a dipeptide (RY) or a single tyrosine residue. The IgE‐binding capacity of the Ara h 2 truncated forms was not altered. CONCLUSION: Ara h 2 undergoes proteolytic processing by peanut proteases that involves C‐terminal removal of a dipeptide. Hence Ara h 2 isolated from peanut extract is a complex mixture of two isoforms expressed by different genes, Ara h 2.01 and Ara h 2.02, as well as truncated forms generated by the proteolytic processing of these isoforms. Copyright © 2010 Society of Chemical Industry     

Synthesis and characterization of shaped ZnS nanocrystals in water in oil microemulsions

Shaped zinc sulfide nanocrystals were synthesized in W/O microemulsions by using cyclohexane/Triton X-100/n-pentanol/water system. Under different synthetic conditions appearance of two distinct morphologies of ZnS nanocrystals, either cubes or nanowires, was proven by transmission electron microscopy (TEM). The ZnS cubes have an average size of about 25 nm, while the ZnS nanowires have 25 Å diameter and length ranging from several hundred nanometers up to a few microns. The X-ray diffraction analysis (XRD) revealed formation of ZnS with cubic zinc blende crystal structure. Due to two dimensional confinement the exciton of ZnS nanowires is blue shifted compared to the bulk material. Four well-resolved photoluminescence bands in visible spectral region were observed upon excitation of cubic ZnS particles, while in the case of ZnS nanowires emission band was observed at 421 nm. The origin of photoluminescence bands was discussed in details.     

CS-US preexposure effects on trace eyeblink conditioning in young rats: Potential implications for functional brain development.

Recent studies of delay eyeblink conditioning (EBC) in young rats have demonstrated different effects of various conditioned and unconditioned stimulus (CS-US) preexposure conditions on learning at different ages. The present study extends this research to trace EBC. Subjects experienced 1 of 3 preexposure conditions (paired CS-US, unpaired CS-US, or no stimuli) at either 20 or 24 days of age. Four days later, they were conditioned using either trace (Experiment 1) or delay (Experiment 2) EBC parameters. Results were similar at both ages tested. Paired preexposure facilitated acquisition of delay but not trace relative to context preexposure. Unpaired preexposure impaired acquisition of both delay and trace. These behavioral findings provide a foundation for hypotheses about the functional maturation of cerebellar, hippocampal, and entorhinal learning circuits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interpositus lesion abolition of the eyeblink conditioned response is not due to effects on performance.

Classical conditioning of the rabbit eyeblink response was used to study the effects of cerebellar lesions on performance in animals trained with low-intensity unconditioned stimuli (UCS). Animals were trained with 1 or 2 low-intensity corneal-airpuff UCSs paired with a tone-conditioned stimulus. This study confirms earlier findings demonstrating the differential effects of lesions of deep cerebellar nuclei on the conditioned and unconditioned responses (CRs and UCRs). Lesions of the anterior interpositus nucleus of the cerebellum in animals that were successfully conditioned abolished CRs without affecting UCR performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of the filler morphology on the crystallization behavior and dielectric properties of the polyvinylidene fluoride-based composite

Ceramic/polymer composites can be chemically stable, mechanically strong, and flexible, which make them candidates for electric devices, such as pressure or temperature sensors, energy storage or harvesting devices, actuators, and so forth. Depending on the application, various electrical properties are of importance. Polymers usually have low dielectric permittivity, but increased dielectric permittivity can be achieved by the addition of the ceramic fillers with high dielectric constant. With the aim to enhance dielectric properties of the composite without loss of flexibility, 5 wt% of BaTiO₃-Fe₂O₃ powder was added into a polyvinylidene fluoride matrix. The powder was prepared by different synthesis conditions to produce core/shell structures. The effect of the phase composition and morphology of the BaTiO₃-Fe₂O₃ core/shell filler on the structure and lattice dynamics of the polymer composites was investigated. Based on the results of the thermal analysis, various parameters of ceramic/polymer composites were determined. Differences in the phase composition and morphology of the filler have an influence on the formation of various polyvinylidene fluoride allomorphs and the degree of crystallinity. Furthermore, the dielectric performances of pure polyvinylidene fluoride and the polymer/ceramic composites were measured.