7,142 research outputs found
Unravelling the Impact of Grape Washing, {SO}2, and Multi-Starter Inoculation in Lab-Scale Vinification Trials of Withered Black Grapes
Wine quality is strongly affected by chemical composition and microbial population of grape must, which, in turn, are influenced by several post-harvest treatments, including grape withering. Different strategies have been suggested to manage the fermenting must microbiota, as it plays a central role in the outcomes of both spontaneous and guided fermentations. This study aimed at evaluating the impact of grape washing, SO2 addition, and selected starter culture inoculation on population dynamics, fermentation kinetics, and main oenological parameters in lab-scale trials, focusing on withered grapes usually used for Amarone production. Although grape washing treatment was effective in removing heavy metals and undesirable microorganisms from grape berry surface, inoculation of multi-starter cultures impacted more fermentation rates. Further, both grape washing and starter inoculation procedures had a remarkable impact on wine chemical characteristics, while 30 mg/L SO2 addition did not significantly affect the fermentation process. In summary, the best strategy in terms of limiting off-flavors and potentially reducing the need for SO2 addition in wine from withered grapes was the use of yeast starters, particularly mixed cultures composed by selected strains of Metschnikowia spp. and Saccharomyces cerevisiae. Application of a washing step before winemaking showed a potential to improve organoleptic characteristics of win
Noise reduction in muon tomography for detecting high density objects
The muon tomography technique, based on multiple Coulomb scattering of cosmic
ray muons, has been proposed as a tool to detect the presence of high density
objects inside closed volumes. In this paper a new and innovative method is
presented to handle the density fluctuations (noise) of reconstructed images, a
well known problem of this technique. The effectiveness of our method is
evaluated using experimental data obtained with a muon tomography prototype
located at the Legnaro National Laboratories (LNL) of the Istituto Nazionale di
Fisica Nucleare (INFN). The results reported in this paper, obtained with real
cosmic ray data, show that with appropriate image filtering and muon momentum
classification, the muon tomography technique can detect high density
materials, such as lead, albeit surrounded by light or medium density material,
in short times. A comparison with algorithms published in literature is also
presented
Precision measurements of Linear Scattering Density using Muon Tomography
We demonstrate that muon tomography can be used to precisely measure the
properties of various materials. The materials which have been considered have
been extracted from an experimental blast furnace, including carbon (coke) and
iron oxides, for which measurements of the linear scattering density relative
to the mass density have been performed with an absolute precision of 10%. We
report the procedures that are used in order to obtain such precision, and a
discussion is presented to address the expected performance of the technique
when applied to heavier materials. The results we obtain do not depend on the
specific type of material considered and therefore they can be extended to any
application.Comment: 16 pages, 4 figure
The effect of moisture on cellulose nanocrystals intended as a high gas barrier coating on flexible packaging materials
Cellulose nanocrystals (CNCs) exhibit outstanding gas barrier properties, which supports their use as a biobased and biodegradable barrier coating on flexible food packaging materials. As highly hydrophilic biopolymers, however, CNCs have a strong sensitivity to water that can be detrimental to applications with fresh foods and in moist conditions due to the loss of barrier properties. In this work, the oxygen and water vapor permeability of polyethylene terephthalate (PET) films coated with CNCs obtained from cotton linters were measured at varying levels of relative humidity, both in adsorption and desorption, and from these data, the diffusion and solubility coefficients were estimated. Therefore, the characterization of CNCs was aimed at understanding the fundamentals of the water-CNCs interaction and proposing counteractions. The CNCs' moisture absorption and desorption isotherms at 25 \uc2\ub0C were collected in the range of relative humidity 0-97% using different techniques and analyzed through GAB (Guggenheim-Anderson-de Boer) and Oswin models. The effects of moisture on the water status, following the freezable water index, and on the crystal structure of CNCs were investigated by Differential Scanning Calorimetry and by X-ray Powder Diffraction, respectively. These findings point to the opportunity of coupling CNCs with hydrophobic layers in order to boost their capabilities as barrier packaging materials
Electrodes Modified with Poly(3,4-Ethylenedioxythiophene) Doped with Sulfonated Polyarylethersulfones: Towards New Conducting Polymers
To overcome the well-known technical problems of Poly(3,4-Ethylenedioxythiophene) (PEDOT), i.e. difficult processability and patterning, due to its poor solubility in common organic and inorganic solvents, PEDOTs characterized by a full miscibility in the reaction solvents used, were successfully synthesized by a direct oxidative polycondensation reaction between Ethylenedioxythiophene (EDOT) and an oxidant species, i.e. ferric sulfate, in four organic reaction solvents: N, N-dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO) and N-methyl-2-pyrrolidone (NMP).
The oxidative polycondensation of EDOT in the presence of Sulfonated Polyarylethersulfone (SPAES) as doping agent characterized by three increasing degree of sulfonation (DS), i.e. 0.5, 0.75 and 1.0 (meq SO3-\ub7g-1 of polymer), was performed for the first time, leading to a new conducting material: PEDOT_SPAES. PEDOT_SPAES can be easily processed and casted onto the surface of glassy carbon electrodes, reaching better electrochemical performances with respect to the precursors.
PEDOT_SPAES chemical structure was investigated via wide-angle scattering (WAXS): comparing WAXS spectra of unmodified PEDOT and commercial PEDOT doped with 2-Naphthalenesulfonic acid, having crystalline structures, with the spectra of PEDOT_SPAESs, that are characterized by amorphous structures, it is possible to assess that for the first time PEDOT-based materials doped with SPAES were synthesized
A Combined XRD, Solvatochromic, and Cyclic Voltammetric Study of Poly (3,4-Ethylenedioxythiophene) Doped with Sulfonated Polyarylethersulfones: Towards New Conducting Polymers
Despite the poor solubility in organic solvents, poly (3,4-ethylenedioxythiophene) (PEDOT) is one of the most successful conducting polymers. To improve PEDOT conductivity, the dopants commonly used are molecules/polymers carrying sulfonic functionalities. In addition to these species, sulfonated polyarylethersulfone (SPAES), obtained via homogeneous synthesis with different degrees of sulfonation (DS), can be used thanks to both the tight control over the DS and the charge separation present in SPAES structure. Here, PEDOTs having enhanced solubility in the chosen reaction solvents (N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N-methyl-2-pyrrolidone) were synthesized via a high-concentration solvent-based emulsion polymerization with very low amounts of SPAES as dopant (1% w/w with respect to EDOT monomer), characterized by different DS. The influence of solvents and of the adopted doping agent was studied on PEDOT_SPAESs analyzing (i) the chemical structure, comparing via X-ray diffraction (XRD) the crystalline structures of undoped and commercial PEDOTs with PEDOT_SPAES\u2019 amorphous structure; (ii) solvatochromic behavior, observing UV absorption wavelength variation as solvents and SPAES\u2019 DS change; and (iii) electrochemical properties: voltammetric peak heights of PEDOT_SPAES cast onto glassy carbon electrodes differ for each solvent and in general are better than the ones obtained for neat SPAES, PEDOTs, and glassy carbon
Search for GeV Gamma-ray Counterparts of Gravitational Wave Events by CALET
We present results on searches for gamma-ray counterparts of the LIGO/Virgo
gravitational-wave events using CALorimetric Electron Telescope ({\sl CALET})
observations. The main instrument of {\sl CALET}, CALorimeter (CAL), observes
gamma-rays from GeV up to 10 TeV with a field of view of nearly 2 sr.
In addition, the {\sl CALET} gamma-ray burst monitor (CGBM) views 3 sr
and sr of the sky in the 7 keV -- 1 MeV and the 40 keV -- 20 MeV
bands, respectively, by using two different crystal scintillators. The {\sl
CALET} observations on the International Space Station started in October 2015,
and here we report analyses of events associated with the following
gravitational wave events: GW151226, GW170104, GW170608, GW170814 and GW170817.
Although only upper limits on gamma-ray emission are obtained, they correspond
to a luminosity of erg s in the GeV energy band
depending on the distance and the assumed time duration of each event, which is
approximately the order of luminosity of typical short gamma-ray bursts. This
implies there will be a favorable opportunity to detect high-energy gamma-ray
emission in further observations if additional gravitational wave events with
favorable geometry will occur within our field-of-view. We also show the
sensitivity of {\sl CALET} for gamma-ray transient events which is the order of
~erg\,cm\,s for an observation of 100~s duration.Comment: 12 pages, 8 figures, 1 table. Accepted for publication in
Astrophysical Journa
On-orbit Operations and Offline Data Processing of CALET onboard the ISS
The CALorimetric Electron Telescope (CALET), launched for installation on the
International Space Station (ISS) in August, 2015, has been accumulating
scientific data since October, 2015. CALET is intended to perform long-duration
observations of high-energy cosmic rays onboard the ISS. CALET directly
measures the cosmic-ray electron spectrum in the energy range of 1 GeV to 20
TeV with a 2% energy resolution above 30 GeV. In addition, the instrument can
measure the spectrum of gamma rays well into the TeV range, and the spectra of
protons and nuclei up to a PeV.
In order to operate the CALET onboard ISS, JAXA Ground Support Equipment
(JAXA-GSE) and the Waseda CALET Operations Center (WCOC) have been established.
Scientific operations using CALET are planned at WCOC, taking into account
orbital variations of geomagnetic rigidity cutoff. Scheduled command sequences
are used to control the CALET observation modes on orbit. Calibration data
acquisition by, for example, recording pedestal and penetrating particle
events, a low-energy electron trigger mode operating at high geomagnetic
latitude, a low-energy gamma-ray trigger mode operating at low geomagnetic
latitude, and an ultra heavy trigger mode, are scheduled around the ISS orbit
while maintaining maximum exposure to high-energy electrons and other
high-energy shower events by always having the high-energy trigger mode active.
The WCOC also prepares and distributes CALET flight data to collaborators in
Italy and the United States.
As of August 31, 2017, the total observation time is 689 days with a live
time fraction of the total time of approximately 84%. Nearly 450 million events
are collected with a high-energy (E>10 GeV) trigger. By combining all operation
modes with the excellent-quality on-orbit data collected thus far, it is
expected that a five-year observation period will provide a wealth of new and
interesting results.Comment: 11 pages, 7 figures, published online 27 February 201
- …