Changes in aliphatic ester composition of white wines during exposition to light. An HS-SPME-GC-MS study

The irradiation of four Italian white wines with a visible light comparable to that encountered in the market place showed a modification in the amount of aliphatic esters in the wines. Aliphatic esters are responsible for fruity aromas in wines. The first wine studied was the Gewürztraminer, a white wine from Alto Adige (Northern Italy). The amounts of the esters presents in the wine decreased. All the curves follow a pseudo-first-order kinetics. This behaviour can be explained assuming a photooxidation process catalysed by riboflavin. When Arneis Blangè was irradiated, ethyl acetate showed an increase after one day of irradiation; its content then decreased and after five days' irradiation its concentration reached a maximum. Conversely, the concentration of other aliphatic esters decreased after one day's irradiation and then increased progressively to reach a maximum after five days' irradiation. The same behaviour was observed with Pecorino wine. In this case, the concentration of the aliphatic esters decreased until the second day of irradiation but increased after five days' irradiation. In the case of the irradiation of Lighea Zibibbo all the esters showed an increase in concentration after one day of irradiation. The concentration decreased after two days' irradiation, and then increased to reach a maximum after seven days of irradiation. The increase in the amount of esters in some wines and, by contrast, the decrease in the same compounds in Gewürztraminer can be explained by considering that, during the irradiation, the pH of Gewürztraminer did not change, while the pH of Arneis Blangè changed following a curve similar to that showed by the concentration of esters. The pH change can be explained assuming the presence of a photocatalytic process induced by the presence of metals in the wines and influencing the amount of tartaric acid.     

Preparation and characterization of manganese, nickel and cobalt ferrites submicron particles in sulfonated crosslinked networks

Magnetic submicron particles of MnFe₂O₄, NiFe₂O₄ or CoFe₂O₄ were created in or around the porous sulfonated beads based on poly(styrene-co-divinylbenzene) using an in situ inorganic precipitation procedure. The copolymer beads were treated with a mixed iron/cobalt chloride electrolyte and the doped copolymer networks were converted to their oxides by reaction with sodium hydroxide and potassium nitrate in aqueous solution. Energy dispersive X-ray spectroscopy (EDS) coupled to scanning electron microscopy (SEM) allowed the observation of the presence of submicron particles in the 0.1-0.5 μm size range, which chemical microanalysis of emitted X-rays revealed the presence of metal oxide particle, such as nickel, manganese or cobalt iron oxide. The morphological features of the binary material particles have depended on the ferrite type. All beads have presented dispersed and agglomerated submicron particles of ferrite located on their surface and inner part as well. Magnetization data of the microbeads showed good ferromagnetic behavior.     

Polymerization of ethylene by chromium acetylacetonate/methylaluminoxane catalyst system

Summary The present paper deals with polymerization of ethylene by chromium acetylacetonate - Cr(acac)₃ - activated by alkylaluminium, e.g. Al(C₂H₅)₃ or Al(i-C₅H₉)₃, or methylaluminoxane (MAO). The influence of polymerization parameters on catalyst performance, such as Al/Cr mole ratio, temperature, aging time, type of cocatalyst, was investigated. High activities were obtained only when MAO was the cocatalyst. The polymers were characterized by size exclusion chromatography (SEC) and differential scanning calorimetry (DSC) analyses. Received: 11 September 1997/Revised version: 5 January 1998/Accepted: 20 March 1998     

Next-generation lithography for 22 and 16 nm technology nodes and beyond

In this paper, next-generation lithography (NGL) for the 22 and 16 nm technology nodes and beyond is reviewed. A broad range of topics, including history, technologies, critical challenges, and the most plausible candidates are discussed. The 22 and 16 nm technology nodes rely on NGL. NGLs have been extensively studied. Because of technological issues, the semiconductor industry has stopped pursuing several NGLs, such as X-ray proximity lithography, ion projection lithography, and scattering with angular li...     

Influence of the addition of lupin sourdough with different lactobacilli on dough properties and bread quality

The aim of this research was to study the effects of solid‐state fermentation (SSF) with Lactobacillus sakei, Pediococcus pentosaceus and P. acidilactici on lupine sourdough parameters and lupine sourdough influence on the physical dough properties and wheat bread quality. The results showed that lactic acid bacteria (LAB) significantly reduced the pH and increased total titratable acidity (TTA) of SSF lupine. The highest protease activity in lupine is excreted by L. sakei (187.1 ± 8.6 PU g^?1), and the highest amylase activity, by P. pentosaceus (155.8 ± 7.5 AU g^?1). Lupine sourdough has a significant effect on the rheological properties of doughs, which affect the baking characteristics of the final product. In conclusion, it can be said that L. sakei, P. pentosaceus and P. acidilactici could be used for lupine SSF, and the addition of up to the 10% SSF lupine products increases the wheat–lupine bread quality.     

Identification of four amino acid residues essential for catalysis in human cytidine deaminase by site-directed mutagenesis and chemical modifications

By site-directed mutagenesis on human cytidine deaminase (CDA), five mutant proteins were obtained: C65A, C99A, C102A, E67D and E67Q. The three cysteine mutants were completely inactive, whereas E67D and E67Q showed a specific activity about 200- and 200000-fold lower, respectively, than the wild-type CDA. Zinc analysis revealed that only E67D, E67Q and C65A contained 1 mol Zn2+/mol subunit as in the wild- type CDA. Kinetic measurements with the specific carboxylic group reagent N-ethoxy-carbonyl-2-ethoxy-1,2-dihydroquinoline performed on wild-type CDA suggest that Glu67 is essential for the catalytic process. Furthermore, when both native and denatured CDA was titrated with 5,5'-dithiobis(2-nitrobenzoic acid) six sulfhydryl groups were detected, whereas in the denatured and reduced enzyme nine such groups were found, according to the sequence data. When p-hydroxymercuriphenyl sulfonate was used, nine sulfhydryl groups were detectable and the release of 1 mol of zinc per mole of CDA subunit was revealed by the metal indicator dye 4-(2-pyridylazo)resorcinol. It seems plausible that the limiting step for the maintenance of zinc in the active site is the formation of coordination between Cys99 and Cys102, whereas Cys65 could lead the zinc to the correct position and orientation within the active site.      

Enhancement of dye sensitized solar cell efficiency via incorporation of upconverting phosphor nanoparticles as spectral converters

Upconverting NaYF₄:Yb³⁺,Er³⁺/NaYF₄ core‐shell (CS) nanoparticles (NPs) were synthesized by thermal decomposition of lanthanide trifluoroacetate precursors and mixed with TiO₂ NPs to fabricate dye‐sensitized solar cells (DSSCs). The CS geometry effectively prevents the capture of electrons because of the surface states and improves photo‐emission. The as‐synthesized CS NPs show upconversion (UC) luminescence, converting near infrared (NIR) light into visible light (450–700 nm), making the photon absorption by the ruthenium‐based dyes (which have little or no absorption in the NIR region) possible. The champion DSSCs fabricated using CS UC NPs (average size = 25 nm) show enhancements of ~12.5% (sensitized with black/N749 dye) and of ~5.5% (sensitized with N719 dye) in overall power conversion efficiency under AM 1.5G illumination. This variation in the enhancement of the DSSC efficiencies for black and N719 dyes is attributed to the difference in the extinction coefficient and the absorption wavelength range of dyes. Incident photon‐to‐current conversion efficiency measurements also evidently showed the photocurrent enhancement in the NIR region of the spectrum because of the UC effect. The results prove that the augmentation in efficiency is primarily due to NIR to visible spectrum modification by the fluorescent UC NPs. Copyright © 2015 John Wiley & Sons, Ltd.     

Ozone Application for Postharvest Disinfection of Tomatoes

Ozone is an effective alternative for the postharvest treatment of fruits and vegetables. The purpose of this study was to evaluate the ozone application in gaseous or aqueous phases for postharvest disinfection of tomatoes (Lycopersicon esculentum Mill) cultivar FA-180. Fruits harvested at the breaker stage were exposed to ozone concentrations of 25 and 45 mg m^?3 for 2 h per day during 16 days, at non-controlled temperature and relative humidity. Exposure to ozone during storage extends the shelf-life of tomatoes, besides preserving its sensory attributes. Mature tomatoes, inoculated with Escherichia coli ATCC 25922, were washed with ozonated water containing 0.5 to 1.0 mg L^?1 during 15 to 30 min. To achieve an adequate disinfection, 1 mg L^?1 and 15 min are recommended. The disinfection with ozonated water was effective.     

Use of biosurfactant in the removal of oil from contaminated sandy soil

The effectiveness of cell‐free rhamnolipid biosurfactant, derived from the culture medium at the end of fermentation was investigated for the removal of two different kinds of oil from contaminated sandy soils. The crude cultivation medium, containing 13.2 g L^?1 of rhamnolipids, had a surface tension, interfacial tension and critical micellar concentration of 30 mN m^?1, 2 mN m^?1 and 60 mg L^?1, respectively. The evaluation of biosurfactant in the culture medium (BM) and oil concentrations in the removal of oil from different contaminated sandy soil was performed using a statistical experimental design tool. Oil in sandy soil, containing predominantly aromatic or paraffinic hydrocarbons (5 to 10% w/w), was removed by as much as 91 and 78%, respectively, in the presence of reduced amounts of BM (6.3 to 7.9 g L^?1). The progress of oil removal was monitored for 101 days and results indicated that removal efficiency in sandy soil with aromatic characteristics was relatively stable over the entire period. Based on these studies, it is concluded that use of a BM was effective in reducing oil concentrations in contaminated sandy soil. Copyright © 2007 Society of Chemical Industry     

Effects of hydrocolloids on chemical properties and cooking quality of gluten‐free spaghetti

The effects of different hydrocolloids on chemical composition and cooking quality of spaghetti based on maize and oat flours were investigated. Rheological and texture properties of the gluten‐free dough were also assessed. Amount of 2% of gellan gum, carboxymethylcellulose, pectin, agar, egg protein powder, tapioca starch, guar seed flour and chitosan were separately added to the formulation. The samples enriched with hydrocolloids generally showed a different rheological behaviour compared with the control samples. As regards chemical composition, spaghetti with chitosan showed a value of insoluble dietary fibres (8.0%) higher than the control ones (3.9%). Moreover, results highlighted that most hydrocolloids improved cooking quality and texture properties of spaghetti (adhesiveness, cooking loss, hardness), thus supporting their application in gluten‐free pasta.