The aim of this study was to evaluate the effect of the microencapsulation (by spray drying) of the whey-native probiotic yeast Kluyveromyces marxianus VM004 in matrices of whey protein concentrate ...(WPC) and water-soluble chitosan (WSCh) on the viability of the yeast during drying and storage and in simulated gastrointestinal conditions. The optimized outlet drying temperature was 68 °C. This temperature allowed obtaining an encapsulation efficiency of 91% for a suspension of 10% (w/v) WPC. Yeasts microencapsulated in WSCh showed a significantly improved tolerance to simulated gastrointestinal conditions in comparison to free yeasts and yeasts microencapsulated in WPC. Besides, the solids content showed a significant influence on the probiotic viability during storage, with a suspension with 30% (w/v) solids (29:1 WPC:WSCh) showing 95% of viability after passing through gastrointestinal conditions. The results allow expanding the development of mixtures of encapsulating materials to improve the probiotic aptitude of a food ingredient powder.
Display omitted
•K. marxianus was successfully microencapsulates in WPC:WSCh by spray drying.•WSCh improved resistance to the gastrointestinal conditions.•Solids content enhances the probiotic count during GI conditions and storage.•WPC:WSCh increase the viability during storage for 90 days at room temperature.
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a major etiologic agent that causes bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS). Shiga toxin (Stx) is the main ...virulence factor of EHEC responsible for the progression to HUS. Although many laboratories have made efforts to develop an effective treatment for Stx-mediated HUS, a specific therapy has not been found yet. Human consumption of bovine colostrum is known to have therapeutic effects against several gastrointestinal infections because of the peptide and proteins (including antibodies) with direct antimicrobial and endotoxin-neutralizing effects contained in this fluid. We have previously demonstrated that colostrum from Stx type 2 (Stx2)-immunized pregnant cows effectively prevents Stx2 cytotoxicity and EHEC O157:H7 pathogenicity. In this study we evaluated the preservation of the protective properties of hyperimmune colostrum against Stx2 (HIC-Stx2) after pasteurization and spray-drying processes by performing in vitro and in vivo assays. Our results showed that reconstituted HIC-Stx2 colostrum after pasteurization at 60°C for 60 min and spray-dried under optimized conditions preserved specific IgG that successfully neutralized Stx2 cytotoxicity on Vero cells. Furthermore, this pasteurized/dehydrated and reconstituted HIC-Stx2 preserved the protective capacity against EHEC infection in a weaned mice model. The consumption of hyperimmune HIC-Stx2 bovine colostrum could be effective for HUS prevention in humans as well as in EHEC control in calves. However, further studies need to be done to consider its use for controlling EHEC infections.
This research is related to the growth and characterization of doped molecular semiconductor metallophthalocyanine-tetracyanoquinodimethane (MPc-TCNQ) films, with M = Fe, Zn, Cu. FT-IR and Raman ...spectroscopies were employed to study the chemical interactions taking place in the MPc-TCNQ films. XRD was carried out to determine the crystalline structure present in the samples, due to the facility of the MPcs to be in alpha and/or beta phases. The thin films were analized by SEM and UV–vis spectroscopy in order to study their morphological and optical properties. The absorption spectra recorded in the UV–Vis region for the deposited samples showed two bands, namely the Q and Soret bands. The absorption coefficient (α) and photon energy (hν) were calculated from the UV–vis spectra, to in turn determine the optic activation energy in each film and its semiconductor behavior. The values obtained for direct transitions due to the crystallinity of the films were: 1.2, 1.4 and 2 eV for FePc-TCNQ (MMFe), ZnPc-TCNQ (MMZn) and CuPc-TCNQ (MMCu), respectively. Additionally, I-V characteristics have been obtained from fabricated glass/ITO/MM/Ag devices using ohmic contacts both after annealing. The electrical properties of the devices, e.g. carrier mobility and concentration of thermally generated holes, were extracted from the J-V characteristics. The results show that the conduction process is ohmic for the MMZn and MMCu devices, at low voltages, while at high voltages, a space-charge-limited conduction (SCLC) is present. The effect of temperature on conductivity was also measured in these samples and the lower thermal activation energy calculated was 0.37 eV for MMZn. Moreover, it was found that the temperature-dependent electric current is always higher for the MMZn device and suggests a semiconductor-like behavior with an important conductivity of the order of 103 S cm−1. Anyhow, in terms not only of electric properties, but also of optic behavior, the results suggest that all three devices manufactured, MMFe, MMCu and MMZn, are of potential use in optoelectronics. The doping effect of TCNQ favors the electronic transport, most likely due to the formation of conduction channels caused by the anisotropy induced by the dopant.
•Synthesis, growth and characterization of the molecular semiconductor MPc-TCNQ (M = Fe, Cu, Zn) films It is proposed•The values obtained for direct transitions due to the crystallinity of the films are: 1.2, 1.4 and 2 eV for MMFe, MMZn and MMCu, respectively•Results show that at low voltages, the conduction process is ohmic for the MMZn and MMCu devices, while at high voltages, SCLC is present•The effect of temperature on conductivity was measured and the lower thermal activation energy calculated was 0.037eV for MMZn
We investigated magnetoelastic coupling through the field-driven transition to the fully polarized magnetic state in quasi-two-dimensional Cu(HF2)(pyz)2BF4 by magnetoinfrared spectroscopy. This ...transition modifies out-of-plane ring distortion and bending vibrational modes of the pyrazine ligand. The extent of these distortions increases with the field, systematically tracking the low-temperature magnetization. These distortions weaken the antiferromagnetic spin exchange, a finding that provides important insight into magnetic transitions in other copper halides.
Through the combined application of Auger electron spectroscopy (AES) and factor analysis (FA), we have studied the oxidation process of titanium under different regimes: bulk and thin film at room ...temperature (RT) and high temperature (HT). While the saturation regime at RT is produced by the formation of a passivated TiO
2 film at the surface of bulk and thick oxide films, the saturation is governed by the substrate/titanium film interactions in the case of thinner films. The stoichiometry of the obtained oxide films also depends on the oxidation process. We found only TiO
2 for RT bulk oxidation, Ti
2O
3 and TiO
2 for HT, and TiO and TiO
2 for thin films. Heating the sample, once the RT saturation was achieved, produces additional oxidation (post-oxidation), but the stoichiometry of the oxide films remains unchanged. For the thinner films, the post-oxidation produces almost no effect.
We present experimental results for methane production from ATJ graphite impacted by atomic and molecular D ions in the energy range 5–60
eV/D. A systematic trend of the methane yields for the ...different molecular species compared at the same impact energy/D is observed: while all three species lead to methane yields that coincide within the experimental uncertainty at the high energy end of the investigated range, at lower energies the yields diverge by progressively larger amounts, with the incident triatomic molecular ion leading to the largest yields per atom, and the atomic ion to the smallest. The difference at the lowest investigated energy (10
eV/D) is about a factor of two. Total chemical sputtering yields obtained by classical molecular dynamic simulations also indicate that molecular projectiles lead to larger yields per atom than atomic projectiles. The energy dependence of the total yield increase obtained by the simulations, however, is different than that observed experimentally for methane production.
Application of a magnetic field offers an incisive opportunity to tune competing interactions in complex materials. Here we probe field-induced changes in the local structure of DyMn2O5 by using ...magnetoinfrared spectroscopy. The high tunability of the dielectric constant and ferroelectric polarization with field is well documented in the literature, but the lattice response on the microscopic level remains unknown. In this work, we reveal the dynamic nature of the local structural response to field and analyze it in terms of calculated mode displacements and local lattice distortions.
Results of chemical sputtering of ATJ graphite by impact of
D
2
+
in the energy range 10–250
eV/D are presented. Our experimental approach is based on the use of a quadrupole mass spectrometer (QMS) ...which samples the partial pressures of selected mass species in the scattering chamber resulting from the incident ion beam. Based on in situ measurements of cracking patterns and QMS sensitivities using calibrated leaks, sputtering yields are presented for the production of methane and acetylene for sample temperatures of 300
K and 800
K. In the energy range 10–60
eV/D, CD
4 appears to be the dominant light stable hydrocarbon detected at room temperature. With increasing
D
2
+
energy, its contribution is found to decrease, while the contribution of C
2D
2 is virtually unchanged. In contrast to what is observed for the sample at room temperature, at 800
K a dramatic increase in the CD
4 production is observed with increasing beam energy, which is also manifested in the production of C
2D
2, although to a smaller degree.
We studied the modifications introduced in the chemical structure of AlF3 films by electron irradiation using Auger electron spectroscopy (AES) and factor analysis (FA). We examined the effects of ...the current density and energy of the electrons on the film composition. We found that the irradiation produces lower aluminum oxidation states (AlFx with 0<x<3, and Al0), and that while this effect is independent of the electron density it presents a clear dependence on the primary electrons energy. After comparison of experiments on the dose dependence of AlF3 and AlFx reduction, for different energies, with Monte Carlo (MC) simulations, we propose possible mechanisms that lead to electron induced fluorine desorption.
