Naphtyl-imidazo-anthraquinones as novel colorimetric and fluorimetric chemosensors for ion sensing

Novel colorimetric and fluorimetric chemosensors for F− and CN− containing anthraquinone and imidazole as signalling/binding sites have been synthesised and characterised. Upon addition of F−, CN− and OH− to acetonitrile solutions of compounds 1-2, a marked colour change from yellow to pink was observed and the fluorescence emission of 1 was switched “on”, whereas for 2 there was a fluorescence quenching. Considering recognition in organic aqueous mixture, it was found that selectivity for CN- was achieved for both receptors, with an easily detectable colour change from yellow to orange. Compounds 1-2 in their deprotonated form, after fluoride addition, were studied as metal ion chemosensors and displayed a drastic change from pink to yellow after metal ion complexation giving a yellow-pink-yellow, reversible colorimetric reaction and a “on-off-on” fluorescence in acetonitrile. The binding stoichiometry between the receptors and the anions and cations was found to be 1:1 and 2:1 respectively. The binding process was also followed by 1H NMR titrations which corroborated the previous findings.Fundação para a Ciência e Tecnologia (FCT

Utilização de biofilmes na redução de perda de massa de goiabas 'Paluma'

Observou- se que os frutos revestidos pelos biofilmes tiveram reduzidas, de maneira significativa, as perdas de massa e de firmeza da polpa

Influence of anaerobic fermentation and yeast inoculation on the viability, chemical composition, and quality of coffee.

Microbial metabolites produced during fermentation migrate into the coffee and can influence the decrease in seed viability and coffee quality. This study evaluated the effects of physiological changes in seed viability on the sensory quality of the beverage using starter cultures through self-induced anaerobic fermentation (SIAF) in Coffea arabica L. for natural and pulped coffee. The yeasts were monitored by real-time polymerase chain reaction (qPCR). High-performance liquid chromatography (HPLC) detected citric, malic, and succinic acids in all fermented coffees. Furthermore, lactic acid was mainly identified in those coffees processed by the SIAF method. Volatile compounds (40) were detected by gas chromatography-mass spectrometry (GC-MS). Alterations in physiological quality were identified, with decreased embryonic viability and cell membrane damage by tetrazolium and electrical conductivity tests. All fermented coffees obtained scores above 80 points. The Torulospora delbrueckii yeast got the best score (86.50) in pulped coffee, and the Candida parapsilosis yeast received the highest score (85.90) in the natural coffee using the SIAF method. The coffees were characterized by aromas and flavors of citrus, caramel, honey, chocolate, and chestnut. The coffee fermentation process with yeast inoculation affected the coffee bean viability but not the beverage's sensory quality, indicating that the use of yeast starters by SIAF favors the production of specialty coffees with differentiated sensory characteristics

Highlights from the Pierre Auger Observatory

The Pierre Auger Observatory is the world's largest cosmic ray observatory. Our current exposure reaches nearly 40,000 km$^2$ str and provides us with an unprecedented quality data set. The performance and stability of the detectors and their enhancements are described. Data analyses have led to a number of major breakthroughs. Among these we discuss the energy spectrum and the searches for large-scale anisotropies. We present analyses of our X$_{max}$ data and show how it can be interpreted in terms of mass composition. We also describe some new analyses that extract mass sensitive parameters from the 100% duty cycle SD data. A coherent interpretation of all these recent results opens new directions. The consequences regarding the cosmic ray composition and the properties of UHECR sources are briefly discussed.Comment: 9 pages, 12 figures, talk given at the 33rd International Cosmic Ray Conference, Rio de Janeiro 201

A search for point sources of EeV photons

Measurements of air showers made using the hybrid technique developed with the fluorescence and surface detectors of the Pierre Auger Observatory allow a sensitive search for point sources of EeV photons anywhere in the exposed sky. A multivariate analysis reduces the background of hadronic cosmic rays. The search is sensitive to a declination band from -85{\deg} to +20{\deg}, in an energy range from 10^17.3 eV to 10^18.5 eV. No photon point source has been detected. An upper limit on the photon flux has been derived for every direction. The mean value of the energy flux limit that results from this, assuming a photon spectral index of -2, is 0.06 eV cm^-2 s^-1, and no celestial direction exceeds 0.25 eV cm^-2 s^-1. These upper limits constrain scenarios in which EeV cosmic ray protons are emitted by non-transient sources in the Galaxy.Comment: 28 pages, 10 figures, accepted for publication in The Astrophysical Journa