We present here a characterization of the low background NaI(Tl) crystal NaI-33 based on a period of almost one year of data taking (891 kg
×
days exposure) in a detector configuration with no use of ...organic scintillator veto. This remarkably radio-pure crystal already showed a low background in the SABRE Proof-of-Principle (PoP) detector, in the low energy region of interest (1–6 keV) for the search of dark matter interaction via the annual modulation signature. As the vetoable background components, such as
40
K, are here sub-dominant, we reassembled the PoP setup with a fully passive shielding. We upgraded the selection of events based on a Boosted Decision Tree algorithm that rejects most of the PMT-induced noise while retaining scintillation signals with > 90% efficiency in 1–6 keV. We find an average background of 1.39 ± 0.02 counts/day/kg/keV in the region of interest and a spectrum consistent with data previously acquired in the PoP setup, where the external veto background suppression was in place. Our background model indicates that the dominant background component is due to decays of
210
Pb, only partly residing in the crystal itself. The other location of
210
Pb is the reflector foil that wraps the crystal. We now proceed to design the experimental setup for the physics phase of the SABRE North detector, based on an array of similar crystals, using a low radioactivity PTFE reflector and further improving the passive shielding strategy, in compliance with the new safety and environmental requirements of Laboratori Nazionali del Gran Sasso.
Sourdough fermentation is one of the oldest food biotechnologies, which has been studied and recently rediscovered for its effect on the sensory, structural, nutritional and shelf life properties of ...leavened baked goods. Acidification, proteolysis and activation of a number of enzymes as well as the synthesis of microbial metabolites cause several changes during sourdough fermentation, which affect the dough and baked good matrix, and influence the nutritional/functional quality. Currently, the literature is particularly rich of results, which show how the sourdough fermentation may affect the functional features of leavened baked goods. In the form of pre-treating raw materials, fermentation through sourdough may stabilize or to increase the functional value of bran fractions and wheat germ. Sourdough fermentation may decrease the glycaemic response of baked goods, improve the properties and bioavailability of dietary fibre complex and phytochemicals, and may increase the uptake of minerals. Microbial metabolism during sourdough fermentation may also produce new nutritionally active compounds, such as peptides and amino acid derivatives (e.g., γ-amino butyric acid) with various functionalities, and potentially prebiotic exo-polysaccharides. The wheat flour digested via fungal proteases and selected sourdough lactobacilli has been demonstrated to be probably safe for celiac patients.
Co3O4, CeO2 and Co3O4-CeO2 mixed oxides with Co/Ce nominal atomic ratio 0.1:5, prepared by co-precipitation method with sodium carbonate, were tested in the oxidation of propene under lean condition ...and the catalyst stability was checked by performing three consecutive heating-cooling cycles. Characterization of the textural properties were performed by surface area measurement BET, X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements. Among the Co3O4-CeO2 mixed oxides, Co3O4 (30 wt%)-CeO2 (70 wt%) gives the best activity attaining full propene conversion at 250 deg C. This sample is characterized by the presence of Co3O4 particles well dispersed and in good contact with ceria according to BET and XRD data and as evidenced by SEM micrographs. Oxygen temperature-programmed desorption (O2-TPD) and C3H6-temperature-programmed reduction (C3H6-TPR) experiments were carried out in order to study the surface and bulk oxygen mobility and to correlate it to the activity. At temperature around 200 deg C, O2-TPD experiments showed the desorption of mobile surface oxygen species for the most active samples, Co3O4 and Co3O4 (30 wt%)-CeO2 (70 wt%). C3H6-TPR experiments for both of the oxides also evidenced a high reactivity at low temperature, especially, for Co3O4 (30 wt%)-CeO2 (70 wt%) giving at 345 deg C an intense peak of CO2 formation. Conversely, the ceria sample showed by C3H6-TPR much less pronounced oxygen bulk mobility, starting to react with propene above 500 deg C and forming only CO. In this case, the catalytic activity of ceria was explained in terms of formation of surface oxygen vacancies which are relevant to the propene oxidation in presence of gaseous oxygen.
This review article explored the catalytic degradation of phenol and some phenols derivates by means of advanced oxidation processes (AOPs). Among them, only the heterogeneous catalyzed processes ...based on catalytic wet peroxide oxidation, catalytic ozonation and catalytic wet oxidation were reviewed. Also selected recent examples about heterogeneous photocatalytic AOPs will be presented.
In details, the present review contains: (i) data concerning catalytic wet peroxide oxidation of phenolic compounds over metal-exchanged zeolites, hydrotalcites, metal-exchanged clays and resins. (ii) Use of cobalt-based catalysts, hydrotalcite-like compounds, active carbons in the catalytic ozonation process. (iii) Activity of transition metal oxides, active carbons and supported noble metals catalysts in the catalytic wet oxidation of phenol and acetic acid.
The most relevant results in terms of catalytic activity for each class of catalysts were reported.
Preliminarily, 146 strains of yeasts were screened for the antifungal activity toward the indicator Penicillium roqueforti DPPMAF1. The strain Meyerozyma guilliermondii LCF1353 was selected and used ...for dough fermentation. The water/salt soluble extract of the dough was analyzed by HPLC and GC/MS-SPME. The synthesis of the extracellular cell wall-degrading enzyme β-1,3-glucanase and ethyl-acetate was shown. The effect on conidia germination mainly suggested a fungistatic activity. M. guilliermondii LCF1353 was used as starter for dough fermentation in combination with Wickeramomyces anomalus 1695 and Lactobacillus plantarum 1A7, which were previously selected for antifungal activity. The growth of the strains was monitored by plate count and molecular techniques, and competitive or antagonistic interactions among them were excluded. Bread started with the combination of M. guilliermondii LCF1353, W. anomalus LCF1695 and L. plantarum 1A7 showed a more prolonged shelf life compared to the other breads. Fungal growth was delayed at least until 14 days of storage, under conditions of high artificial inoculum. The bread manufactured with the above combination showed good chemical and textural characteristics and, as shown by sensory analysis, it was appreciated for elasticity, color and taste.
► 146 strains of yeasts were screened for the antifungal activity. ► Meyerozyma guilliermondii LCF1353 was selected for antifungal activity. ► Antifungal activity was characterized by in vitro assays. ► The synthesis of ethyl-acetate, ethanol and of a cell wall-degrading enzyme was shown. ► Breads fermented with the selected yeast were tested during storage.
Two strains (POM1 and C2) or LP09 of Lactobacillus plantarum, which were previously isolated from tomatoes and carrots, and another commercial strain of L. plantarum (LP09), were selected to singly ...ferment (30°C for 120h) pomegranate juice (PJ) under standardized protocol. PJs were further stored at 4°C for 30days. Filtered PJ, not added of starters (unstarted PJ), was used as the control. After fermentation, all starters grew to ca. 9.0LogCFU/mL. Viable cells of strain LP09 sharply decreased during storage. The other two strains survived to ca. 7.0 and 8.0LogCFU/mL. Lactic acid bacteria consumed glucose, fructose, malic acid, and branched chain and aromatic amino acids. The concentration of free fatty acids increased for all started PJs. Compared to unstarted PJ, color and browning indexes of fermented PJs were preferable. The concentration of total polyphenolic compounds and antioxidant activity were the highest for started PJs, with some differences that depended on the starter used. Fermentation increased the concentration of ellagic acid, and enhanced the antimicrobial activity. Fermented PJs scavenged the reactive oxygen species generated by H2O2 and modulated the synthesis of immune-mediators from peripheral blood mononuclear cells (PBMC). Unstarted and fermented PJs inhibited the growth of K562 tumor cells. The sensory attributes of fermented PJs were preferred. The fermentation of pomegranate juice would represent a novel technology option, which joins health-promoting, sensory and preservative features to exploit the potential of pomegranate fruits.
•Lactobacillus plantarum POM1 and C2 were suitable starters for pomegranate juice fermentation.•Pomegranate juice highlighted some peculiar metabolic traits of lactic acid bacteria.•Lactic acid fermentation increased the concentration of ellagic acid.•The fermented pomegranate juice improved health-promoting, sensory and preservative features.
The catalytic oxidation of toluene, chosen as VOC probe molecule, was investigated over Co
3
O
4
, CeO
2
and over Co
3
O
4
–CeO
2
mixed oxides and compared with the catalytic behavior of a ...conventional Pt(1 wt%)/Al
2
O
3
catalyst. Complete toluene oxidation to carbon dioxide and water was achieved over all the investigated systems at temperatures below 500 °C. The most efficient catalyst, Co
3
O
4
(30 wt%)–CeO
2
(70 wt%), showed full toluene conversion at 275 °C, comparing favorably with Pt/Al
2
O
3
(100% toluene conversion at 225 °C).
We present new results on the radiopurity of a 3.4-kg NaI(Tl) crystal scintillator operated in the SABRE proof-of-principle detector setup. The amount of potassium contamination, determined by the ...direct counting of radioactive 40K, is found to be 2.2 ± 1.5 ppb , lowest ever achieved for NaI(Tl) crystals. With the active veto, the average background rate in the crystal in the 1–6 keV energy region of interest (ROI) is 1.20 ± 0.05 counts / day / kg / keV , which is a breakthrough since the DAMA/LIBRA experiment. Our background model indicates that the rate is dominated by 210Pb and that about half of this contamination is located in the polytetrafluoroethylene reflector. We discuss ongoing developments of the crystal manufacture aimed at the further reduction of the background, including data from purification by zone refining. A projected background rate lower than ∼ 0.2 counts / day / kg / keV in the ROI is within reach. These results represent a benchmark for the development of next-generation NaI(Tl) detector arrays for the direct detection of dark matter particles.
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