Multicolor up conversion emission and color tunability in Yb/Tm/Ho triply doped heavy metal oxide glasses

Multicolor and white light emissions have been achieved in Yb³⁺, Tm³⁺ and Ho³⁺ triply doped heavy metal oxide glasses upon laser excitation at 980 nm. The red (660 nm), green (547 nm) and blue (478 nm) up conversion emissions of the rare earth (RE) ions triply doped TeO₂–GeO₂–Bi₂O₃–K₂O glass (TGBK) have been investigated as a function of the RE concentration and excitation power of the 980 nm laser diode. The most appropriate combination of RE in the TGBK glass host (1.6 wt% Yb₂O₃, 0.6 wt% Tm₂O₃ and 0.1 wt% Ho₂O₃) has been determined with the purpose to tune the primary colors (RGB) respective emissions and generate white light emission by varying the pump power. The involved infrared to visible up conversion mechanisms mainly consist in a three-photon blue up conversion of Tm³⁺ ions and a two-photon green and red up conversions of Ho³⁺ ions. The resulting multicolor emissions have been described according to the CIE-1931 standards.     

Quantifying the robustness of a broth-based Escherichia coli O157:H7 growth model in ground beef

The robustness of a microbial growth model must be assessed before the model can be applied to new food matrices; therefore, a methodology for quantifying robustness was developed. A robustness index (RI) was computed as the ratio of the standard error of prediction to the standard error of calibration for a given model, where the standard error of calibration was defined as the root mean square error of the growth model against the data (log CFU per gram versus time) used to parameterize the model and the standard error of prediction was defined as the root mean square error of the model against an independent data set. This technique was used to evaluate the robustness of a broth-based model for aerobic growth of Escherichia coli 0157:H7 (in the U.S Department of Agriculture Agricultural Research Service Pathogen Modeling Program) in predicting growth in ground beef under different conditions. Comparison against previously published data (132 data sets with 1,178 total data points) from experiments in ground beef at various experimental conditions (4.8 to 45 degrees C and pH 5.5 to 5.9) yielded RI values ranging from 0.11 to 2.99. The estimated overall RI was 1.13. At temperatures between 15 and 40 degrees C, the RI was close to and smaller than 1, indicating that the growth model is relatively robust in that temperature range. However, the RI also was related (P < 0.05) to temperature. By quantifying the predictive accuracy relative to the expected accuracy, the RI could be a useful tool for comparing various models under different conditions.     

Magnetic Mn5Ge3 nanocrystals embedded in crystalline Ge: a magnet/semiconductor hybrid synthesized by ion implantation

The integration of ferromagnetic Mn₅Ge₃ with the Ge matrix is promising for spin injection in a silicon-compatible geometry. In this paper, we report the preparation of magnetic Mn₅Ge₃ nanocrystals embedded inside the Ge matrix by Mn ion implantation at elevated temperature. By X-ray diffraction and transmission electron microscopy, we observe crystalline Mn₅Ge₃ with variable size depending on the Mn ion fluence. The electronic structure of Mn in Mn₅Ge₃ nanocrystals is a 3d⁶ configuration, which is the same as that in bulk Mn₅Ge₃. A large positive magnetoresistance has been observed at low temperatures. It can be explained by the conductivity inhomogeneity in the magnetic/semiconductor hybrid system.     

Development of whey-based beverages

This paper considers beverages consisting of whey, fruit components (orange, pear, peach, and apple), citric acid and sucrose. It also offers their optimal composition. The dry matter of the fruit component, the pH of the beverage and its sucrose content were independent variables. Blends were prepared in accordance with the factorial design. After pasteurization, they were exposed to a sensor analysis so that the following characteristics were estimated: flavour, odour, colour, sediment, appearance and total quality (sum of the previous factors). By applying the regression analysis method, a mathematical model of each characteristic was derived. None of the characteristic functions had an extreme, so the maxima lay at the boundaries of the independent variables (6% of dry matter and 4% or 2% of sucrose ). Only the pH changed within a narrow range. The statistical method has shown that the quality of blends with orange and pear mostly depends on the sucrose content, while the quality of blends with peach and apple depends on the dry matter of the fruit. Interaction of dry matter and sucrose is most significant for the blend with pear, while the balance between sucrose and pH strongly depends on the quality of all the other products. The peach–whey beverage containing 6% of dry matter and 2% of sucrose as well as having pH 3.6 proved to be the best.     

Yeast dynamics during spontaneous wine fermentation of the Catalanesca grape

Although the use of starter cultures in winemaking has improved the reproducibility and predictability of wine quality, the main drawback to this practice is the lack of the typical traits of wines produced by spontaneous fermentation. In this study, we identified for the first time the yeast population occurring during spontaneous fermentation of the Catalanesca white grape, a variety from Campania (Italy). Yeasts were identified using molecular tools: PCR-DGGE and partial sequence analysis of the 26S rRNA gene from isolates. Eighteen different species belonging to 11 different genera were identified. Hanseniaspora spp., Issatchenkia spp. and Candida spp. were the dominant yeasts during the early stages of fermentation, while the middle and end phases were dominated by Saccharomyces cerevisiae. Four species of Issatchenkia spp., rarely isolated from wine fermentation, were found in this study accounting for the 33.5% of the total isolates. The RAPD-PCR screening of the isolates followed by partial rRNA gene sequencing proved to be a very effective approach to first differentiate the isolates and then identify yeast species involved in a wine making procedure. The results show very high yeast diversity in this natural wine fermentation and also highlight the possibility of considering interesting autochthonous strains for starter selection.     

Bioactive compounds extracted by liquid and supercritical carbon dioxide from citrus peels

This work investigated the extraction of bioactive compounds from citrus peels, an agri-food waste. Carbon dioxide (CO₂), an eco-friendly solvent, was used under liquid and supercritical conditions to perform the extractions from orange, tangerine and lemon peels. The possibility of using ethanol as a cosolvent at small percentages up to 20% was also studied. The extraction yield, total polyphenolic content, individual polyphenolic profile, antiradical activity and volatile organic compounds of the extracts were evaluated. The highest yields were obtained when 20% ethanol was used as a cosolvent in both liquid (at 20 MPa and 20 °C) and supercritical (at 30 MPa and 60 °C) CO₂ extraction. In addition, the extracts obtained with liquid CO₂ + 20% ethanol showed the highest content of naringin (35.26, 44.05 and 19.86 mg g^-1 in orange, tangerine and lemon peel extracts, respectively) and terpenes, in particular limonene. This type of extract also showed the highest antiradical activity (31.78–59.51 µmolTE g^-1) as measured by both ABTS·+ and DPPH·. These findings show that the extraction with a liquid CO₂ and ethanol mixture could be a valid alternative to traditional solvent extraction using 80% less organic solvent and producing extracts with high antiradical capacity and rich in volatile organic compounds.     

Cinnamon essential oil and cinnamaldehyde in the control of bacterial biofilms formed on stainless steel surfaces

The antibacterial effects of Cinnamomum cassia essential oil (EO) and cinnamaldehyde were evaluated against single- and mixed-species cultivation of enteropathogenic Escherichia coli (EPEC) and Listeria monocytogenes attached to stainless steel. A central composite rotational design with two variables and eleven assays was used to optimize the concentrations (0.00–1.00% v/v for the EO and 0.00–0.80% v/v for cinnamaldehyde) and contact times (1–21 min). The models generated were validated, and the effectiveness of C. cassia EO and cinnamaldehyde was compared with that of commercially available chemical sanitizers. Cinnamaldehyde and C. cassia EO proved to be efficient alternatives to commercial chemical sanitizers in the reduction or elimination of sessile bacterial cells. The activity of these natural compounds was, in most cases, equivalent or superior to that of the chemical sanitizers tested. However, L. monocytogenes was more resistant than EPEC to C. cassia EO and cinnamaldehyde, and the bacterial association in mixed-species biofilms made them more susceptible to these compounds.     

Milk thickeners do not influence anthropometric indices in childhood

BACKGROUND: Pediatric obesity is an important risk factor for chronic diseases in adulthood. Some infant feeding practices may contribute to childhood obesity. OBJECTIVE: To investigate whether the introduction of milk thickeners to bottle-fed infants between 3 and 6 months of age was associated with higher anthropometric measurements and indices at 1 and 4 years of age. METHODS: A population-based birth cohort study was conducted in 1993 in the urban area of Pelotas, Brazil. Information was obtained at birth, at 1, 3, 6, and 12 months, and at 4 years. Data were analyzed from the 596 children for whom information was available from all follow-up visits. The exposure of interest was the use of milk thickener (flour added to cow's milk) between the third and sixth months of life. The outcomes investigated were weight and length/height and the anthropometric indices weight-for-age, length/height-for-age, and weight-for-length/height z-scores at 1 and 4 years. RESULTS: The prevalence of use of milk thickener at any time between the third and sixth months was 44.6%. In the adjusted analysis, children who received milk thickener were, on average, 160 g heavier and 0.5 cm longer at I year than those who did not receive it. Weight-for-age and length-for-age z-scores were positively associated with use of milk thickener. No association was observed between this feeding practice and weight-for-length z-score. In the adjusted analysis, no effect of use of milk thickener on any of the anthropometric outcomes studied was observed at 4 years. CONCLUSIONS: No association was found between the use of milk thickeners and weight-for-length/height z-scores in the first and fourth years of life. Future studies in other contexts would be helpful to further test this hypothesis.     

Evaluation of microbial diversity during the manufacture of Fior di Latte di Agerola, a traditional raw milk pasta-filata cheese of the Naples area

Microbial diversity of the raw milk for the production of Fior di Latte di Agerola and its changes during cheesemaking were studied. Viable counts showed that at the end of curd ripening, loads of lactic acid bacteria, both mesophilic and thermophilic rods and cocci, higher than those commonly evidenced in similar cheeses produced by using natural or commercial starters, were detected. Identification of 272 isolates, supported by molecular diagnostic aids, evidenced representative cultures of a high number of bacterial taxa of interest as participating in the process, although most of the isolates belonged to Lactococcus lactis and Lactobacillus helveticus species. RAPD-PCR and REA-PFGE biotyping were performed for the isolates of the above species and it was shown that most of the strains isolated from the raw milk occurred during the whole cheesemaking process, and an active role of these strains in the fermentation was supposed. The results offer further proof of the importance of the raw milk as source of technologically interesting strains of lactic acid bacteria capable of driving the fermentation of traditional cheeses.     

Soluble axially substituted phthalocyanines: Synthesis and nonlinear optical response

This review lays special stress on describing the synthesis of soluble axially substituted or bridged indium, gallium and titanium phthalocyanine complexes and their electronic absorption characteristics, photophysical and nonlinear optical properties. The enhanced solubility of the axially substituted or bridged phthalocyanine monomers and dimers, compared to the chloro analogues, shows that the usual tendency of phthalocyanines to form aggregates can be effectively suppressed by axial substitution. Axial substitution in phthalocyanine complexes has provoked relevant changes on the electronic structure of the molecule by altering the π-electronic distribution due to the dipole moment of the central metal-axial ligand bond. The nanosecond nonlinear absorption and the optical limiting of indium, gallium and titanium phthalocyanines seem to be dominated by a strong triplet state absorption in the optical region comprised between the Q- and B-bands in their UV/Vis absorption spectra. Graphical Abstract A series of highly soluble axially substituted and bridged phthalocyanine and naphthalocyanine complexes have been synthesized. Axial substitution in phthalocyanine complexes has provoked relevant changes on the electronic structure of the molecule by altering the π-electronic distribution due to the dipole moment of the central metal-axial ligand bond.