Heat-induced aggregation of whey proteins in the presence of κ-casein or sodium caseinate

Aggregates were formed by heating mixtures of whey protein isolate (WPI) and pure κ-casein or sodium caseinate at pH 7 and 0.1 M NaCl. The aggregates were characterized by static and dynamic light scattering and size exclusion chromatography. After extensive heat-treatment at 80 °C for 24 h, almost all whey proteins and κ-casein formed mixed aggregates, but a large proportion of the sodium caseinate did not aggregate. At a given WPI concentration the size of the aggregates decreased with increasing κ-casein or sodium caseinate concentration, but the overall self-similar structure of the aggregates was the same. The presence of κ-casein or caseinate therefore inhibited growth of the heat-induced whey protein aggregates. The results were discussed relative to the reported chaperone-like activity of casein molecules towards heat aggregation of globular proteins.     

DFT-Study on Antioxydant of 3-Alkyl-4-P henylacetylam i no-1H-1,2,4-Triazol-5-O nes and Its Derivatives

In this article, we have performed B3LYP/6-31＋G（d） calculations of geometrical and reaction enthalpies of antioxidant mechanisms for ADPHT 1-4 （3-alkyl-4-phenylacetylamino-lH-1,2,4-triazol-5-ones） and its derivatives： HAT （hydrogen atom transfer）, SET-PT （single electron transfer-proton transfer） and SPLET （sequential proton-loss electron transfer） were investigated in gas and solution-phases. Solvent contribution to enthalpies was computed employing integral equation formalism IEF-PCM （integral equation formalism method） method. It turned out that the lowest BDEs （bond dissociation energies） is obtained for C-H bonds due to captodative effect in various media. Results indicate that HAT mechanism represents the most anticipated process in gas-phase from thermodynamic point of view. But, the SPLET represents the thermodynamically preferred reaction pathway in solvents （2-propanol, acetonitrile, DMF （N,N-dimethylformamide） and water）. The authors showed that bond dissociation energies, IP （ionization potential） and PA （proton affinity） are sufficient to evaluate the thermodynamically preferred mechanism.     

Field emission properties of carbon nanotube pastes examined using design of experiments

Field emission properties of screen-printed carbon nanotube (CNT) pastes were investigated by design of experiments (DOE) using three, two-level, input factors. Characterization showed that the multi-walled carbon nanotubes (MWNTs) with a diameter of approximately 5 nm containing 5 wt. % of carbonaceous impurities were almost completely burnt out after heating to 600°C in air, while 96% of the sample remained even up to 800°C in a nitrogen atmosphere. Experimental measurements using a diode structure for eight sample groups revealed an emission current density of 52–87 μA/cm² in an electric field of 5 V/μA and a field enhancement factor of 12,079–16,922, assuming the work function of MWNTs to be 5 eV, thereby demonstrating superior emission properties with the sample containing a larger amount of MWNTs. A long-term, 110-h reliability test showed a stable emission property with a half-life of 6,000 h.     

Cluster formation and phase separation in mixtures of sodium κ-carrageenan and sodium caseinate

Mixtures of the polysaccharide κ-carrageenan (KC) and caseinate proteins (SC) from milk were investigated at pH 7 in aqueous solution using confocal scanning laser microscopy and light scattering. Phase separation was observed at higher concentrations and the phase diagram was established. In the mixtures SC was observed to form large aggregates mediated by a relatively small amount of KC. At small KC concentrations the aggregates were initially relatively small and could be characterized by light scattering. At higher KC concentrations or on longer storage at 20 °C, dense clusters with a radius of a few microns were formed that slowly precipitated. The fraction of precipitated protein increased linearly with increasing KC concentration, but was independent of the protein concentration. It increased with decreasing pH from about 20% at pH 8 to 100% at pH 5.     

Dispersion and field emission properties of multi-walled carbon nanotubes by high-energy milling

Multi-walled carbon nanotubes (MWNTs) were high-energy milled for 2 h in texanol after a polycarboxylic acid polymeric dispersant had been added in order to enhance the dispersion. The degree of MWNT dispersion was significantly enhanced by high-energy milling compared to the intact sample, which increased the density of surface-exposed MWNTs with a screen-printed paste. However, the emission properties of high-energy milled MWNTs did not show such a high emission current density relative to their increased surface-exposed density. Further investigation using Raman spectroscopy and X-ray diffraction evidenced the milling-induced MWNT damage, which explained the relatively lower emission current density of high-energy milled MWNTs.     

Etude des parametres de controle et de commande du procede de deshydratation–impregnation par immersion, sur systeme probatoire automatise: application au traitement des pommes “Golden”

The work presented here is a study aiming at the control and checking of dewatering and impregnation soaking process (DISP). The studies are carried out using an automatic experimental system. Apples of the “Golden” variety are used exclusively. Two kinds of agitation system are studied; mechanical agitation using a vertical screw without an end, and hydraulic agitation. There is hardly any difference between the two kinds of agitation; parameter variations are almost the same. These results are compared with those obtained in agitated thermostated water-bath system and they show that mass transfers are better on the experimental system than with the water-bath system. Temperature influences were studied for the agitated thermostated water-bath system only. They show that the increase of temperature favours water loss and sugar intake. We have shown that during experiments with old syrup, only the conductivity of syrup is higher but kinetics of water loss, solute intake and weight reduction are not significantly affected.     

Gel formation of mixtures of κ-carrageenan and sodium caseinate

Gelation of sodium κ-carrageenan (KC) in the presence of sodium caseinate (SC) was investigated by oscillating shear rheology. The effect of adding NaCl and KCl was investigated. Temperature ramps showed that SC had no influence on the critical gelation temperature, but increased the melting temperature when that of the pure gels was less than about 30 °C. The presence of SC also increased the gel strength of weak KC gels. Light scattering and confocal laser scanning microscopy showed that the proteins associated with the KC network. The rheology of the gels indicated that the mixed gels contained bonds involving both SC and KC in addition to pure KC bonds. At relatively high SC content the former type of bonds dominated.     

Cold tests of A 10-GHz gyrotron cavity

Experiments have been conducted to characterize a gyrotron cavity designed to operate in theTE ₀₂₁ mode at 10 GHz. Cavity excitation was accomplished via a coupling hole introduced into the cavity wall and mode detection was carried out by means of two experimental arrangements. In the first, electromagnetic energy is coupled into a receiving waveguide through a small second hole drilled in the opposite side of the cavity. The other scheme uses a horn antenna to receive the power reradiated by the open resonator. Both schemes are discussed regarding mode detection, and measured data includes resonant frequency, loadedQ factor, axial electric field profile and farfield radiation pattern. Evaluation of the loadedQ factor is based on bandwidth measurements whereas standing-wave electric field profile is determined by using perturbation techniques. For severalTE modes, close agreeent between theory and experiment is found.