29 research outputs found
Catalytic hydrogenation of crude hexanoic acid, easily obtained by anaerobic fermentation of grape pomace
The transition from fossil resources to renewable ones represents an urgent need. Biomasses are promising feedstocks, potentially exploitable through novel bio-catalytic processes, such as acidogenic fermentation
to carboxylic acids, which can be further converted into more value-added bio-products through cascade chemical approaches, such as hydrogenation to corresponding alcohols/esters. In this work, the optimization of the hydrogenation of commercial hexanoic acid to 1-hexanol and hexyl hexanoate was first investigated. For this
purpose, 5 wt% Re/C resulted active and selective towards 1-hexanol production. The same catalyst was further tested for the hydrogenation of crude hexanoic acid, obtained by fermentation of red and white grape pomaces. Hydrogenation of these crude hexanoic acid mixtures confirmed the promising performances of 5 wt% Re/C, achieving the complete substrate conversion with a prevailing selectivity to 1-hexanol (~58 mol%), rather than to hexyl hexanoate (~30 mol%). Moreover, the use of an acid support, such as Al2O3, markedly shifted the selectivity towards hexyl hexanoate (~51 mol%). This observation was further demonstrated by testing physical mixtures of 5 wt% Re/C and different amounts of acidic niobium phosphate. Based on these promising results, exploitation of
grape pomace for 1-hexanol/hexyl hexanoate production, to use as bio-fuels or bio-solvents, represents a smart possibility
Radio imaging of the Subaru/XMM-Newton Deep Field - III. Evolution of the radio luminosity function beyond z=1
We present spectroscopic and eleven-band photometric redshifts for galaxies
in the 100-uJy Subaru/XMM-Newton Deep Field radio source sample. We find good
agreement between our redshift distribution and that predicted by the SKA
Simulated Skies project. We find no correlation between K-band magnitude and
radio flux, but show that sources with 1.4-GHz flux densities below ~1mJy are
fainter in the near-infrared than brighter radio sources at the same redshift,
and we discuss the implications of this result for spectroscopically-incomplete
samples where the K-z relation has been used to estimate redshifts. We use the
infrared--radio correlation to separate our sample into radio-loud and
radio-quiet objects and show that only radio-loud hosts have spectral energy
distributions consistent with predominantly old stellar populations, although
the fraction of objects displaying such properties is a decreasing function of
radio luminosity. We calculate the 1.4-GHz radio luminosity function (RLF) in
redshift bins to z=4 and find that the space density of radio sources increases
with lookback time to z~2, with a more rapid increase for more powerful
sources. We demonstrate that radio-loud and radio-quiet sources of the same
radio luminosity evolve very differently. Radio-quiet sources display strong
evolution to z~2 while radio-loud AGNs below the break in the radio luminosity
function evolve more modestly and show hints of a decline in their space
density at z>1, with this decline occurring later for lower-luminosity objects.
If the radio luminosities of these sources are a function of their black hole
spins then slowly-rotating black holes must have a plentiful fuel supply for
longer, perhaps because they have yet to encounter the major merger that will
spin them up and use the remaining gas in a major burst of star formation.Comment: Accepted for publication in MNRAS: 36 pages, including 13 pages of
figures to appear online only. In memory of Stev
The XMM Cluster Survey: X-ray analysis methodology
The XMM Cluster Survey (XCS) is a serendipitous search for galaxy clusters
using all publicly available data in the XMM-Newton Science Archive. Its main
aims are to measure cosmological parameters and trace the evolution of X-ray
scaling relations. In this paper we describe the data processing methodology
applied to the 5,776 XMM observations used to construct the current XCS source
catalogue. A total of 3,675 > 4-sigma cluster candidates with > 50
background-subtracted X-ray counts are extracted from a total non-overlapping
area suitable for cluster searching of 410 deg^2. Of these, 993 candidates are
detected with > 300 background-subtracted X-ray photon counts, and we
demonstrate that robust temperature measurements can be obtained down to this
count limit. We describe in detail the automated pipelines used to perform the
spectral and surface brightness fitting for these candidates, as well as to
estimate redshifts from the X-ray data alone. A total of 587 (122) X-ray
temperatures to a typical accuracy of < 40 (< 10) per cent have been measured
to date. We also present the methodology adopted for determining the selection
function of the survey, and show that the extended source detection algorithm
is robust to a range of cluster morphologies by inserting mock clusters derived
from hydrodynamical simulations into real XMM images. These tests show that the
simple isothermal beta-profiles is sufficient to capture the essential details
of the cluster population detected in the archival XMM observations. The
redshift follow-up of the XCS cluster sample is presented in a companion paper,
together with a first data release of 503 optically-confirmed clusters.Comment: MNRAS accepted, 45 pages, 38 figures. Our companion paper describing
our optical analysis methodology and presenting a first set of confirmed
clusters has now been submitted to MNRA
Human rhinovirus promotes STING trafficking to replication organelles to promote viral replication
Human rhinovirus (HRV), like coronavirus (HCoV), are positive-strand RNA viruses that cause both upper and lower respiratory tract illness, with their replication facilitated by concentrating RNA-synthesizing machinery in intracellular compartments made of modified host membranes, referred to as replication organelles (ROs). Here we report a non-canonical, essential function for stimulator of interferon genes (STING) during HRV infections. While the canonical function of STING is to detect cytosolic DNA and activate inflammatory responses, HRV infection triggers the release of STIM1-bound STING in the ER by lowering Ca2+, thereby allowing STING to interact with phosphatidylinositol 4-phosphate (PI4P) and traffic to ROs to facilitates viral replication and transmission via autophagy. Our results thus hint a critical function of STING in HRV viral replication and transmission, with possible implications for other RO-mediated RNA viruses
The Role of Galaxies and AGN in Reionising the IGM - I: Keck Spectroscopy of 5 < z < 7 Galaxies in the QSO Field J1148+5251
We introduce a new method for determining the influence of galaxies and
active galactic nuclei (AGN) on the physical state of the intergalactic medium
(IGM) at high redshift and illustrate its potential via a first application to
the field of the QSO J1148+5251. By correlating the spatial positions
of spectroscopically-confirmed Lyman break galaxies (LBGs) with fluctuations in
the Lyman alpha forest seen in the high signal-to-noise spectrum of a
background QSO, we provide a statistical measure of the typical escape fraction
of Lyman continuum photons close to the end of cosmic reionisation. Here we use
Keck DEIMOS spectroscopy to locate 7 colour-selected LBGs in the redshift range
and confirm a faint AGN. We then examine
the spatial correlation between this sample and Ly/Ly
transmission fluctuations in a Keck ESI spectrum of the QSO. Interpreting the
statistical HI proximity effect as arising from faint galaxies clustered around
the detected LBGs, we translate the observed mean Ly transmitted flux
around an average detected LBG into a constraint on the mean escape fraction
at . We also report evidence of
the individual transverse HI proximity effect of a luminous LBG via a
Ly transmission spike and two broad Ly transmission spikes
around the AGN. We discuss the possible origin of such associations
which suggest that while faint galaxies are primarily driving reionisation,
luminous galaxies and AGN may provide important contributions to the UV
background or thermal fluctuations of the IGM at . Although a limited
sample, our results demonstrate the potential of making progress using this
method in resolving one of the most challenging aspects of the contribution of
galaxies and AGN to cosmic reionisation.Comment: 21 pages, 16 figures, the version accepted in MNRA
Unwilling or willing but unable: can horses interpret human actions as goal directed?
International audienceSocial animals can gain important benefits by inferring the goals behind the behavior of others. However, this ability has only been investigated in a handful of species outside of primates. In this study, we tested for the first time whether domestic horses can interpret human actions as goal directed. We used the classical "unwilling versus unable" paradigm: an experimenter performed three similar actions that have the same outcome, but the goal of the experimenter differed. In the unwilling condition, the experimenter had no intention to give a piece of food to a horse and moved it out of reach when the horse tried to eat it. In the two unable conditions, the experimenter had the intention to give the food to the horse but was unable to do so, either because there was a physical barrier between them or because of the experimenter's clumsiness. The horses (n = 21) reacted differently in the three conditions: they showed more interest in the unable conditions, especially in the unable clumsy condition, than in the unwilling condition. These results are similar to results found in primates with the same paradigm and suggest that horses might have taken the experimenter's goal, or even intentions, into account to adapt their behavior. Hence, our study offers more insights into horse interspecific social cognition towards humans
Evaluation of a prototype dynamic laryngoplasty system in vitro with an equine vacuum airflow system
To evaluate a prototype dynamic laryngoplasty system (DLPS) in a static airflow model.Experimental.Ten equine larynges.The right arytenoid was fixed in abduction in all specimens. A left-sided laryngoplasty was performed with No. 2 Fiberwire and a FASTakII anchor. Each larynx was tested in a static airflow model. The system was adjusted to a flow rate of 55âL/s and prelaryngeal pressure of 12âmm Hg prior to testing in maximal arytenoid abduction. In phase 1, the left suture was loosened, shortened, and tested in 3-mm steps from 0 to 30âmm. In phase 2, the suture was tied with the DLPS in position at a target left-to-right quotient angle (LRQ) of 0.5. The DLPS was activated to target psi of 0, 25, and 50 for testing. Translaryngeal impedance (TLI), LRQ, cross-sectional areas (CSA), and resultant change in LRQ and CSA between, before, and during airflow testing were calculated.In phase 1, TLI was reduced by suture shortening up to 6âmm (Pâ=â.001) but not by additional shortening (Pâ>â.05). In phase 2, activation of the DLPS reduced the TLI from 0 psi (0.43â±â0.08âmm Hg/L/s) to 25 psi (0.16â±â0.04âmm Hg/L/s, P
Catalytic hydrogenation of crude hexanoic acid, easily obtained by anaerobic fermentation of grape pomace
According to European climate law 2021, the progressive transition from traditional fossil sources to renewable ones represents, more than even, an urgent need. In this regard, biomasses can be exploited, not only adopting the already developed thermochemical treatments, but also through novel bio-catalytic pathways, including the production of carboxylic acids via acidogenic fermentation. Besides, the combination of a bio-chemical approach with a traditional chemical one could make possible to achieve a better exploitation of the biomass, aimed at the sustainable and selective
production of value-added bio-products. Remarkably, carboxylic acids can be further chemically converted into more value-added bio-products, which can be advantageously proposed within the pharmaceutical, polymer, and fuel industries. In this context, a strategic conversion path is the hydrogenation of the carboxylic acids to the corresponding alcohols
and/or esters. In this work, the optimization of the catalytic hydrogenation of hexanoic acid to 1-hexanol and hexyl hexanoate, as the main products of interest, has been first investigated. For this purpose, different rhenium-supported catalysts have been tested in the hydrogenation of commercial hexanoic acid, evaluating the synergistic effects of the metal loading and support acidity on the conversion and selectivity to 1-hexanol and hexyl hexanoate. The choice of rhenium as the hydrogenation metal is appropriate for economic reasons and for its resistance to poisoning. Rhenium catalysts resulted very active, the adoption of acid supports influencing the selectivity towards hexyl hexanoate formation. Instead, 5 wt% Re on neutral carbon resulted more selective towards 1-hexanol production and, for this purpose, this catalyst was tested for the hydrogenation of a crude hexanoic acid, easily obtained by fermentation of grape pomace and simple insolubilization step. This agri-food waste biomass, whose worldwide generation is about 9 Mt/year, represents a clean source of carbohydrates, that can be exploited by catalytic conversion, instead of being landfilled or used for low value
applications. It is noteworthy that the obtained hexanoic acid-rich liquor has been hydrogenated without any further purification treatment, making the entire proposed bio-chemical process simpler and more sustainable. Hydrogenation of crude hexanoic acid has confirmed the promising performances of 5 wt% Re/C, achieving an almost complete conversion
of the substrate (~98 mol%) and prevailing selectivity in 1-hexanol (~58 mol%), rather than hexyl hexanoate (~30 mol%), under the previously optimized reaction conditions. According to these results, the novel exploitation of grape pomace for the combined production of 1-hexanol/hexyl hexanoate mixtures to be used as bio-fuels or bio-solvents appears a promising route
Diagnosis and treatment of confirmed and suspected primary hyperparathyroidism in equids: 17 cases (1999-2016
Background Primary hyperparathyroidism is uncommon in equids. Objectives To describe the diagnostic findings and efficacy of treatment in equids with primary hyperparathyroidism. Study design Retrospective case series describing 16 horses and one mule. Methods Cases were identified by retrospective review of records at Cornell University and via an ACVIM listserv query. Inclusion criteria were an equid with hypercalcemia, normal renal function and high parathyroid hormone (PTH) or histopathological diagnosis of a parathyroid adenoma. Equids with normal PTH and PTHârelated protein (PTHrP) in the face of hypercalcemia were included as suspect cases. Results The most common presenting complaints were weight loss (12/17) and hypercalcemia (10/17). PTH was above reference range in 12/17 cases. Suspected parathyroid tumours were localised in 12/14 equids imaged using ultrasonography alone (2/3), technetium 99m Tc sestamibi scintigraphy alone (1/1) or both modalities (9/10). Three horses did not have imaging performed. Surgical exploration successfully excised tumours in six of 10 cases. Five were located at the thoracic inlet, and surgery resulted in complete cure. One tumour was excised from the thyroid lobe, and the horse remained hypercalcemic. Four other cases explored surgically, four treated medically and three that were not treated also remained hypercalcemic. Main limitations The small study size prohibited statistical analysis. Conclusions Parathyroid adenomas in equids can be successfully localised with ultrasonography and scintigraphy. Surgical excision appears more likely to be successful for single gland disease at the thoracic inlet