A comparative numerical study of hybrid-stabilized argon–water electric arc

The paper presents numerical simulations of the discharge and the near-outlet regions of the hybrid-stabilized argon–water electric arc. Two different numerical methods for solving the set of conservative equations for the continuity, momentum and energy have been applied. The major difference between the results using the two methods occurs in the temperature distribution in arc fringes within the discharge chamber. This fact influences the potential drop, overpressure, reabsorption of radiation and arc efficiency. It is shown that the radial profiles of temperature at the exit nozzle are less influenced by different temperature distribution within the discharge chamber. Comparison with chosen experimental temperature profiles shows very good agreement.     

Antifungal activity of lauric acid derivatives against Aspergillus niger

The antifungal effects of lauric acid and four lauric acid derivatives (monolauroylglycerol, D-laurate A, T-laurate A, 6-O-lauroysucrose) were tested on the spore germination and the growth rate of Aspergillus niger DMF 0801. The results showed that the tested substances varied in their antifungal activity and they also confirmed the relation of the structure of tested substances and their antifungal effects. Monolauroylglycerol at concentration level between 0.2 and 1.8 mmol l^-1 caused the highest inhibition of spore outgrowths whereas 6-O-lauroysucrose at concentration between 0.05 and 1.8 mmol l^-1 did not exhibit inhibition of spore germination. The inhibition of colony growth rate was detected mainly at presence of 6-O-lauroysucrose.     

Lipidomic Study of Precursors of Endocannabinoids in Freshwater Bryozoan Pectinatella magnifica

Freshwater bryozoan Pectinatella magnifica was collected from a sand pit (South Bohemia). The total lipids after extraction from lyophilized bryozoans were analyzed using high‐performance liquid chromatography/high‐resolution negative tandem electrospray mass spectrometry. A total of 19 lipid classes were identified, including N‐acyl‐substituted phospholipids, that is, N‐acylphosphatidylethanolamine and N‐acylphosphatidylserine in their plasmenyl forms. Based on gas chromatography/mass spectrometry of 3‐pyridylcarbonyl (picolinyl) esters, a very unusual fatty acid was identified, namely 24:7n‐3 (all‐cis‐3,6,9,12,15,18,21‐tetracosaheptaenoic acid). The presence of polyunsaturated fatty acids in individual classes is very specific: arachidonic and eicosapentaenoic acids being predominantly bound as amides in N‐acyl phospholipids, that is, diacyl‐N‐acylphosphatidylethanolamines (NAPtdEtn), plasmenyl‐N‐acylphosphatidyl ethanolamines (PlsNAPtdEtn), diacyl‐N‐acylphosphatidylserines (NAPtdSer), and plasmenyl‐N‐acylphosphatidylserines (PlsNAPtdSer). While 24:6n‐3 was identified in the sn‐2 position of several phospholipids, 24:7n‐3 was identified in only two plasmalogens, that is, PlsNAPtdEtn and PlsNAPtdSer. Thanks to the tandem mass spectrometry, we managed to identify the position of all acyl groups in both diacyl‐ and also in alkenyl‐acyl‐(plasmenyl) molecular species of N‐acylphospholipids. The identification of the molecular species of N‐acyl‐substituted phosphatidylethanolamine and phosphatidylserine, including their plasmalogen forms, in the freshwater bryozoan P. magnifica has enabled the identification of endogenous cannabinoid precursors.     

Arylpiperazine dopamineric ligands protect neuroblastoma cells from nitric oxide (NO)-induced mitochondrial damage and apoptosis

The protective ability of novel arylpiperazine-based dopaminergic ligands against nitric oxide (NO)-mediated neurotoxicity is investigated. The most potent neuroprotective arylpiperazine identified during the study was N-{4-[2-(4-phenyl-piperazin-1-yl)ethyl]-phenyl}picolinamide, which protected SH-SY5Y human neuron-like cells from the proapoptotic effect of NO donor sodium nitroprusside (SNP) by decreasing oxidative stress, mitochondrial membrane depolarization, caspase activation and subsequent phosphatydilserine externalization/DNA fragmentation. The protective effect was associated with the inhibition of proapoptotic (JNK, ERK, AMPK) and activation of antiapoptotic (Akt) signaling pathways, in the absence of interference with intracellular NO accumulation. The neuroprotective action of arylpiperazines was shown to be independent of dopamine receptor binding, as it was not affected by the high-affinity D?/D? receptor blocker butaclamol. These results reported support the further study of arylpiperazines as potential neuroprotective agents.     

Head rotations in the play of Hanuman langurs (semnopithecus entellus): Description and analysis of function.

Although head rotations are frequent patterns in play behavior in many mammalian species and differ from head movements used in other contexts, they have not been quantitatively described and their function remains unclear. The head rotations occurring in the play behavior of free-ranging Hanuman langurs (Semnopithecus entellus) were described from videotaped sequences. The authors tested 2 possible hypotheses about their function. Either the head rotations serve to create unexpected situations and should therefore occur in both solitary and social play and also be very variable, or they serve as play signals and should therefore occur only in social play and be ritualized. If head rotations have both functions, they should be less variable in social play. The data revealed that head rotations were very variable and were present both in solitary and social play. Furthermore, there was no difference in the variability between the head rotations present in the 2 types of play. The results do not support the function of head rotations as play signals but, rather, suggest that head rotations may serve to create unexpected situations in play. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impedance measurement of growth of lactic acid bacteria in the presence of nisin and lysozyme

Effect of nisin (0.500 g/l), lysozyme (0.035 g/l) and the mix of nisin (0.500 g/l) and lysozyme (0.035 g/l) against two nisin-producing lactococci strains, three non-nisin-producing lactococci strains and four lactobacilli strains with antimicrobial activity was determined by the impedimetric method. None of the tested lactococci and lactobacilli strains were inhibited by lysozyme at concentration of 0.035 g/l. Only the nisin-producing lactococci strains were resistant to nisin at 0.500 g/l, the other lactococci and lactobacilli were inhibited by nisin at 0.500 g/l intensively. The mix of lysozyme and nisin displayed a comparable effect to the nisin addition against the used lactococci strains and was very variable depending on the strain of tested lactobacilli. The impedimetric method was shown to be convenient for screening the growth abilities of lactococci and lactobacilli in the presence of antimicrobial components.     

Association of phospholipid-cholesterol micelles with rat heart mitochondria: Stimulators and inhibitors

The uptake of emulsified labeled lipids by rat heart mitochondria was studied. Divalent cations greatly stimulated uptake of cholesterol in emulsions containing phospholipids; the effect increased with increasing atomic number. Epinephrine and norepinephrine were also stimulatory. Lipid-depleted mitochondria were less effective in taking up cholesterol unless lecithin or serum lipids were included in the emulsion. Addition of iodoacetamide did not inhibit uptake, while use of heated mitochondria or extremes of pH augmented lipid uptake. Thus the process appears to be non-enzymatic. While lecithin emulsions showed no visible change on addition of calcium ions, phosphatidylethanolamine emulsions became turbid and the turbidity was largely removed by addition of heparin. Heparin as well as chondroitin sulfate B and nonionic detergent did inhibit lipid uptake by mitochondria. The possible role of such nonenzymatic lipid uptake in membrane formation and cholesterol accumulation is discussed.     

The joint mixing action of the static pre-mixer and the rotating drum mixer – Discrete element method approach

In this study, the mixing performance of coupled mixing action of the Komax static mixer (which is used as a pre-mixer) and rotating drum (applied as the final mixer) was explored in the maize meal mixing operation. The main objective of this paper was to predict the behaviour of the previously grinded maize particles, during the mixing process in static mixer and drum mixer, and to explore the possibilities to shorten the mixing time in the main mixer (in order to reduce the energy consumption).Three different experiments were performed: in the first experiment, possibilities of static mixer were explored, second experiment showed the mixing performance of rotating drum, and the combination of these two mixing devices was investigated in the third experiment. Homogeneity of the obtained mixtures was determined experimentally, by the “Microtracers” method.The Discrete Element Method was used for modelling of granular flow in the pre-mixing and final mixing applications, and to predict the inter-particle mixing quality within a static mixer and the rotating drum mixer. The results of the numerical simulation are compared with appropriate experimental results. The possible industrial application of this model could be the optimization of parameters of mixing systems taking into account the quality and the duration of the mixing process.