757 research outputs found
Towards more circular office fit-outs: a socio-technical descriptive framework of office fit-out processes
Ethyl (S)-3-hydroxybutyrate ((S)-E3HB) is naturally found as part of kiwi fruit aroma and is an important
precursor for the production of several pharmaceuticals. (S)-E3HB can be produced in a whole cell
biotransformation process from Ethylacetoacetate (EAA) using the yeast Saccharomyces cerevisiae. One way
of improving the sustainability of such processes may be their integration into novel biorefinery concepts, which
requires research to characterize the process and the byproduct formation. In this study it could be shown that
(S)-E3HB biocatalysis with S. cerevisiae can be performed under anaerobic conditions with production rates
between 4.0 × 10-3 and 2.5 × 10-2 g(S)-E3HB gbiomass
-1 h-1 which are similar to the rates in conventional aerobic
processes. The byproduct spectrum allows for the integration of the new anaerobic biotransformation process
into a recently invented biorefinery concept in which the side product CO2 is further utilized to produce methane
Element-Specific Depth Profile of Magnetism and Stoichiometry at the La0.67Sr0.33MnO3/BiFeO3 Interface
Depth-sensitive magnetic, structural and chemical characterization is
important in the understanding and optimization of novel physical phenomena
emerging at interfaces of transition metal oxide heterostructures. In a
simultaneous approach we have used polarized neutron and resonant X-ray
reflectometry to determine the magnetic profile across atomically sharp
interfaces of ferromagnetic La0.67Sr0.33MnO3 / multiferroic BiFeO3 bi-layers
with sub-nanometer resolution. In particular, the X-ray resonant magnetic
reflectivity measurements at the Fe and Mn resonance edges allowed us to
determine the element specific depth profile of the ferromagnetic moments in
both the La0.67Sr0.33MnO3 and BiFeO3 layers. Our measurements indicate a
magnetically diluted interface layer within the La0.67Sr0.33MnO3 layer, in
contrast to previous observations on inversely deposited layers. Additional
resonant X-ray reflection measurements indicate a region of an altered Mn- and
O-content at the interface, with a thickness matching that of the magnetic
diluted layer, as origin of the reduction of the magnetic moment.Comment: 13 pages, 4 figures, supplemental material include
El efecto del nivel de proteÃna y lÃpidos sobre la acción dinámica especÃfica y la excreción postprandial en sub-adultos del camarón blanco Litopenaeus vannamei
The study aimed to evaluate the effect of 4 levels of dietary protein (20, 30, 40 and 50%) and lipids (2, 4, 8 and 16%) on the magnitude and duration of specific dynamic action (SDA) and postprandial nitrogen excretion in the subadult white shrimpLitopenaeus vannameiusing computer-controlled metabolic chambers (continuous-flow respirometer). We determined the oxygen consumption rate at 1 h intervals until the postprandial oxygen consumption rate returned to the pre-feeding level. Shrimp fed all the diets had significantly higher respiration rates after feeding due to the SDA. Oxygen consumption, the SDA coefficient and the SDA magnitude increased notably with increasing dietary protein content. Shrimp fed the 20% protein diet had the lowest levels of pre- and post-feeding respiration and the smallest SDA. A significant change in the SDA coefficient relative to each lipid level was not demonstrable. Additionally, nitrogenous excretion increased with an increase of dietary protein but not with an increase of lipid level. By estimating the SDA of subadults, the response to standard metabolic rate (SMR) was lower than that reported for juveniles and postlarva white shrimp
Modelling the strongest silicate emission features of local type 1 AGN
We measure the 10 and m silicate features in a sample of 67 local
() type 1 active galactic nuclei (AGN) with available {\it Spitzer}
spectra dominated by non-stellar processes. We find that the m silicate
feature peaks at m with a strength (Si = ln
f(spectrum)/f(continuum)) of , while the
m one peaks at m with a strength of
. We select from this sample sources with the strongest
10m silicate strength (, 10 objects). We carry
out a detailed modeling of the IRS/{\it Spitzer} spectra by comparing several
models that assume different geometries and dust composition: a smooth torus
model, two clumpy torus models, a two-phase medium torus model, and a
disk+outflow clumpy model. We find that the silicate features are well modeled
by the clumpy model of Nenkova et al. 2008, and among all models those
including outflows and complex dust composition are the best (Hoenig et al.
2017). We note that even in AGN-dominated galaxies it is usually necessary to
add stellar contributions to reproduce the emission at the shortest
wavelengths.Comment: Accepted for publication in Ap
The impact and effectiveness of the general public wearing masks to reduce the spread of pandemics in the UK: a multidisciplinary comparison of single-use masks versus reusable face masks
During the coronavirus (COVID-19) pandemic, the UK government mandated the use of face masks in various public settings and recommended the use of reusable masks to combat shortages of medically graded single-use masks in healthcare. To assist decision-making on the choice of masks for future pandemics, where shortages may not be a contributing factor, the University College London (UCL) Plastic Waste Innovation Hub has carried out a multidisciplinary comparison between single-use and reusable masks based on their anatomy, standalone effectiveness, behavioural considerations, environmental impact and costs. Although current single-use masks have a higher standalone effectiveness against bacteria and viruses, studies show that reusable masks have adequate performance in slowing infection rates of respiratory viruses. Material flow analysis (MFA), life cycle assessment (LCA) and cost comparison show that reusable masks have a lower environmental and economic impact than single-use masks. If every person in the UK uses one single-use mask each day for a year, it will create a total of 124,000 tonnes of waste, 66,000 tonnes of which would be unrecyclable contaminated plastic waste (the masks), with the rest being the recyclable packaging typically used for transportation and distribution of masks. Using reusable masks creates >85% less waste, generates 3.5 times lower impact on climate change and incurs 3.7 times lower costs. Further behavioural research is necessary to understand the extent and current practices of mask use; and how these practices affect mask effectiveness in reducing infection rates. Wearing single-use masks may be preferred over reusable masks due to perceptions of increased hygiene and convenience. Understanding behaviour towards the regular machine-washing of reusable masks for their effective reuse is key to maximise their public health benefits and minimise environmental and economic costs
A Fast bipolar H2 outflow from IRAS 16342-3814: an old star reliving its youth
Some evolved stars in the pre-planetary nebula phase produce
highly-collimated molecular outflows that resemble the accretion-driven jets
and outflows from pre-main sequence stars. We show that IRAS 16342-3814 (the
Water Fountain Nebula) is such an object and present K-band integral field
spectroscopy revealing a fast (> 150 km/s) bipolar H2 outflow. The H2 emission
is shock excited and may arise in fast-moving clumps, accelerated by the
previously observed precessing jet. The total luminosity in H2 is 0.37
L which is comparable with that of accretion-powered outflows from
Class 0 protostars. We also detect CO overtone bandhead emission in the
scattered continuum, indicating hot molecular gas close to the centre, a
feature also observed in a number of protostars with active jets. It seems
likely that the jet and outflow in IRAS 16342-3814 are powered by accretion
onto a binary companion.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical
Societ
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