Sustainable organic dyes from winemaking lees for photoelectrochemical dye-sensitized solar cells

During the last two decades, Dye Sensitized Solar Cells (DSSCs) have received a great deal of attention as a promising, low-cost alternative to conventional silicon photovoltaic devices. Natural dye molecules can be used as a sensitizer for their low cost, good light absorbance, easy preparation process, and biodegradability. In this study, dyes were obtained from wine lees, the last by-product of winemaking process, supplied by a venetian winery (Italy). Polyphenols, like tannins and anthocyanins, which were extracted from winemaking lees, were adsorbed on a nanostructured ordered mesoporous titanium dioxide, previously treated at different temperatures (400-600 ffiC). Both dyes and titania semiconductor samples were studied with different techniques. The tests were carried out on prototypes to evaluate the cell power and the photocurrent generated under simulated solar light irradiation. The obtained solar energy conversion efficiencies are comparable to those that were reported in literature by using organic dyes extracted from vegetables, fruits, and plants. It is significant that these dyes are largely available and cost effective, since recovered from a waste otherwise to be disposed of, opening up a perspective of feasibility for inexpensive and environmentally friendly dye solar cells to generate green electricity and transforming agri-food waste into a resource

Adsorption of CO2 on Amine-Grafted Activated Carbon

Adsorption on amine-grafted materials may be a potentially attractive alternative to capturing CO2 from power plants. Activated Carbon (AC) has been proposed as a potential adsorbent due to its natural affinity for CO2 and to the possibility of tailoring textural properties and surface chemistry to enhance capacity and selectivity. An AC commercial sample was functionalized with monoethanolamine (MEA) in order to obtain nitrogen-enriched AC with two different loadings (ACN10 and ACN20). Samples characterization was carried out by nitrogen adsorption/desorption isotherms at 77 K, XPS, FTIR and adsorption microcalorimetry. CO2 equilibrium adsorption experiments were accomplished in a volumetric system in the pressure range of vacuum up to 10 bar, at 298 and 348 K. Impregnated activated carbon presented different chemical and textural characteristics with a significant reduction in the surface area, depending on the amine loading. A high adsorption capacity at room temperature and high pressure was observed for the pristine AC as compared to the modified samples. The reduction in surface area affected the adsorption capacity of CO2 at 298 and 348 K, except for adsorption on ACN10 at 348 K, which suggests the occurrence of chemisorption.Fil: Bezerra, Diôgo P.. Universidade Federal do Ceara. Department of Chemical Engineering. Grupo de Pesquisa em Separações por Adsorção; BrasilFil: Da Silva, Francisco W. M.. Universidade Federal do Ceara. Department of Chemical Engineering. Grupo de Pesquisa em Separações por Adsorção; BrasilFil: de Moura, Pedro A. S.. Universidade Federal do Ceara. Department of Chemical Engineering. Grupo de Pesquisa em Separações por Adsorção; BrasilFil: Sapag, Manuel Karim. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; ArgentinaFil: Vieira, Rodrigo S.. Universidade Federal do Ceara. Department of Chemical Engineering. Grupo de Pesquisa em Separações por Adsorção; BrasilFil: Rodriguez Castellon, Enrique. Universidad de Malaga. Facultad de Ciencias; EspañaFil: de Azevedo, Diana C. S.. Universidade Federal do Ceara. Department of Chemical Engineering. Grupo de Pesquisa em Separações por Adsorção; Brasi

The Carnegie Supernova Project I: photometry data release of low-redshift stripped-envelope supernovae

The first phase of the Carnegie Supernova Project (CSP-I) was a dedicated supernova follow-up program based at the Las Campanas Observatory that collected science data of young, low-redshift supernovae between 2004 and 2009. Presented in this paper is the CSP-I photometric data release of low-redshift stripped-envelope core-collapse supernovae. The data consist of optical (uBgVri) photometry of 34 objects, with a subset of 26 having near-infrared (YJH) photometry. Twenty objects have optical pre-maximum coverage with a subset of 12 beginning at least five days prior to the epoch of B-band maximum brightness. In the near-infrared, 17 objects have pre-maximum observations with a subset of 14 beginning at least five days prior to the epoch of J-band maximum brightness. Analysis of this photometric data release is presented in companion papers focusing on techniques to estimate host-galaxy extinction (Stritzinger et al., submitted) and the light-curve and progenitor star properties of the sample (Taddia et al., submitted). The analysis of an accompanying visual-wavelength spectroscopy sample of ~150 spectra will be the subject of a future paper.Comment: Updated a couple of small error

Transition from Fireball to Poynting-flux-dominated Outflow in Three-Episode GRB 160625B

The ejecta composition is an open question in gamma-ray bursts (GRB) physics. Some GRBs possess a quasi-thermal spectral component in the time-resolved spectral analysis, suggesting a hot fireball origin. Others show a featureless non-thermal spectrum known as the "Band" function, consistent with a synchrotron radiation origin and suggesting that the jet is Poynting-flux-dominated at the central engine and likely in the emission region as well. There are also bursts showing a sub-dominant thermal component and a dominant synchrotron component suggesting a likely hybrid jet composition. Here we report an extraordinarily bright GRB 160625B, simultaneously observed in gamma-rays and optical wavelengths, whose prompt emission consists of three isolated episodes separated by long quiescent intervals, with the durations of each "sub-burst" being $\sim$ 0.8 s, 35 s, and 212 s, respectively. Its high brightness (with isotropic peak luminosity L$_{\rm p, iso}\sim 4\times 10^{53}$ erg/s) allows us to conduct detailed time-resolved spectral analysis in each episode, from precursor to main burst and to extended emission. The spectral properties of the first two sub-bursts are distinctly different, allowing us to observe the transition from thermal to non-thermal radiation between well-separated emission episodes within a single GRB. Such a transition is a clear indication of the change of jet composition from a fireball to a Poynting-flux-dominated jet.Comment: Revised version reflecting the referees' comments. 27 pages, 11 figures, 5 tables. The final edited version will appear in Nature Astronom

A High Pressure Operando Spectroscopy Examination of Bimetal Interactions in ‘Metal Efficient’ Palladium/In2O3/Al2O3 Catalysts for CO2 Hydrogenation

CO2 hydrogenation to methanol has the potential to serve as a sustainable route to a wide variety of hydrocarbons, fuels and plastics in the quest for net zero. Synergistic Pd-In2O3 (Palladium on Indium Oxide) catalysts show high CO2 conversion and methanol selectivity, enhancing methanol yield. The identity of the optimal active site for this reaction is unclear, either as a Pd−In alloy, proximate metals, or distinct sites. In this work, we demonstrate that metal-efficient Pd-In2O3 species dispersed on Al2O3 can match the performance of pure Pd-In2O3 systems. Further, we follow the evolution of both Pd and In sites, and surface species, under operando reaction conditions using X-ray Absorption Spectroscpy (XAS) and infrared (IR) spectroscopy. In doing so, we can determine both the nature of the active sites and the influence on the catalytic mechanism

The Carnegie Supernova Project II: Early observations and progenitor constraints of the Type Ib supernova LSQ13abf

Supernova LSQ13abf was discovered soon after explosion by the La Silla-QUEST Survey and then followed by the Carnegie Supernova Project II at its optical and near-IR wavelengths. Our analysis indicates that LSQ13abf was discovered within two days of explosion and its first ≈10 days of evolution reveal a B-band light curve with an abrupt drop in luminosity. Contemporaneously, the V-band light curve exhibits a rise towards a first peak and the r- and i-band light curves show no early peak. The early light-curve evolution of LSQ13abf is reminiscent of the post-explosion cooling phase observed in the Type Ib SN 2008D, and the similarity between the two objects extends over weeks. Spectroscopically, LSQ13abf also resembles SN 2008D, with P Cygni He I features that strengthen over several weeks. Spectral energy distributions are constructed from the broad-bandphotometry, a UVOIR light curve is constructed by fitting black-body (BB) functions, and the underlying BB-temperature and BB-radius profiles are estimated. Explosion parameters are estimated by simultaneously fitting an Arnett model to the UVOIR light curve and the velocity evolution derived from spectral features, and an in addition to a post-shock breakout cooling model to the first two epochs of the bolometric evolution. This combined model suggests an explosion energy of 1.27 ± 0.23 × 1051 ergs, in addition to a relatively high ejecta mass of 5.94 ± 1.10 M, a 56Ni mass of 0.16 ± 0.02 M, and a progenitor-star radius of 28.0 ± 7.5 R. The ejecta mass suggests the origins of LSQ13abf lie with a > 25 M zero-age-main-sequence mass progenitor and its estimated radius is three times larger compared to the result obtained from the same analysis applied to observations of SN 2008D, and nine times larger compared to SN 1999ex. Alternatively, a comparison of hydrodynamical simulations of 20-25 M zero-age-main-sequence progenitors that evolve to pre-supernova envelope masses of 10 M and extended (∼100 R) envelopes also broadly match the observations of LSQ13abf.Fil: Stritzinger, M. D.. University Aarhus; DinamarcaFil: Taddia, F.. University Aarhus; DinamarcaFil: Holmbo, S.. University Aarhus; DinamarcaFil: Baron, E.. University Aarhus; Dinamarca. Oklahoma State University; Estados UnidosFil: Contreras, C.. University Aarhus; Dinamarca. Las Campanas Observatory; ChileFil: Karamehmetoglu, E.. University Aarhus; Dinamarca. Stockholms Universitet; SueciaFil: Phillips, M.M.. Las Campanas Observatory; ChileFil: Sollerman, J.. Stockholms Universitet; SueciaFil: Suntzeff, N.B.. Texas A&M University; Estados UnidosFil: Vinko, J.. University of Texas at Austin; Estados UnidosFil: Ashall, C.. Florida State University; Estados UnidosFil: Avila, C.. Las Campanas Observatory; ChileFil: Burns, C. R.. Carnegie Observatories; Estados UnidosFil: Campillay, A.. Las Campanas Observatory; ChileFil: Castellon, S.. Las Campanas Observatory; ChileFil: Folatelli, Gaston. Universidad Nacional de La Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Galbany, L.. Universidad de Granada; EspañaFil: Hoeflich, Peter. Florida State University; Estados UnidosFil: Hsiao, E. Y.. Florida State University; Estados UnidosFil: Marion, G. H.. University of Texas at Austin; Estados UnidosFil: Morrell, Nidia Irene. Las Campanas Observatory; ChileFil: Wheeler, J. C.. University of Texas at Austin; Estados Unido

The first 48: Discovery and progenitor constraints on the Type Ia supernova 2013gy

We present an early-phase $g$-band light curve and visual-wavelength spectra of the normal Type Ia supernova (SN) 2013gy. The light curve is constructed by determining the appropriate S-corrections to transform KAIT natural-system $B$- and $V$-band photometry and Carnegie Supernova Project natural-system $g$-band photometry to the Pan-STARRS1 $g$-band natural photometric system. A Markov Chain Monte Carlo calculation provides a best-fit single power-law function to the first ten epochs of photometry described by an exponent of $2.16^{+0.06}_{-0.06}$ and a time of first light of MJD 56629.4$^{+0.1}_{-0.1}$, which is $1.93^{+0.12}_{-0.13}$ days (i.e., $<48$~hr) before the discovery date (2013 December 4.84 UT) and $-19.10^{+0.12}_{-0.13}$ days before the time of $B$-band maximum (MJD 56648.5$\pm0.1$). The estimate of the time of first light is consistent with the explosion time inferred from the evolution of the Si II $\lambda$6355 Doppler velocity. Furthermore, discovery photometry and previous nondetection limits enable us to constrain the companion radius down to $R_c \leq 4\,R_{\odot}$. In addition to our early-time constraints, we use a deep +235 day nebular-phase spectrum from Magellan/IMACS to place a stripped H-mass limit of $< 0.018\,M_{\odot}$. Combined, these limits effectively rule out H-rich nondegenerate companions

Blue-space availability, environmental quality and amenity use across contrasting socioeconomic contexts

Over 60% of the global population are expected to live in urban areas by 2050. Urban blue spaces are critical for biodiversity, provide a range of ecosystem services, and can promote human health and wellbeing. Despite this, access to blue space is often unequally distributed across socioeconomic gradients, and the availability of quality blue space could extend to environmental justice issues. Three stages of analysis were carried out in Mexico City, Mexico and Bristol, UK to (i) assess associations between blue space and socioeconomic metrics at a regional scale, (ii) apply a rapid assessment tool to assess amenity, access and environmental quality, (iii) consider local quality across socioeconomic gradients at a regional scale. Still water availability was indicative of higher socioeconomic status, but contrasting city evolutions underpinned differences. Locally, there were environmental gradients from more complex to disturbed habitats that influenced potential wellbeing and amenity benefits. In combination, this may exacerbate inequalities and risk increasing ecosystem disservices. If cities are to be socially, and environmentally resilient to higher levels of disturbance in the future, healthy ecosystems will be key. However, further research is needed to address various dimensions of injustice in urban areas beyond blue space distribution

Asymptomatic neurocognitive disorders in patients infected by HIV: fact or fiction?

Neurocognitive disorders are emerging as a possible complication in patients infected with HIV. Even if asymptomatic, neurocognitive abnormalities are frequently detected using a battery of tests. This supported the creation of asymptomatic neurocognitive impairment (ANI) as a new entity. In a recent article published in BMC Infectious Diseases, Magnus Gisslén and colleagues applied a statistical approach, concluding that there is an overestimation of the actual problem. In fact, about 20% of patients are classified as neurocognitively impaired without a clear impact on daily activities. In the present commentary, we discuss the clinical implications of their findings. Although a cautious approach would indicate a stricter follow-up of patients affected by this disorder, it is premature to consider it as a proper disease. Based on a review of the data in the current literature we conclude that it is urgent to conduct more studies to estimate the overall risk of progression of the asymptomatic neurocognitive impairment. Moreover, it is important to understand whether new biomarkers or neuroimaging tools can help to identify better the most at risk population