A Sustainable Approach for the Downstream Processing of Bacterial Polyhydroxyalkanoates: State-of-the-art and latest developments

Bioplastics have emerged as a platform to reduce our dependence on fossil fuels. Polyhydroxyalkanoates (PHAs) are a family of biodegradable polyesters with large potential in consumer goods and medical applications. These polymers accumulate in prokaryotic microbes and their recovery is a challenging, often under explored, operation. In the past, oil-derived solvents and chemicals have been widely used as extracting agents, compromising the “environmentally-friendly” claim of bioplastics. Furthermore, the large amount of chemicals and solvents required at the industrial level would negatively impact the economics of the process. The present review presents the latest advances in the field of downstream operations for PHA recovery emphasizing those green technologies with scaling-up feasibility. As for the upstream and fermentation stages, the extraction process needs to be carefully optimized to accomplish a competitive production of PHAs

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Formation of X-ray emitting stationary shocks in magnetized protostellar jets

X-ray observations of protostellar jets show evidence of strong shocks heating the plasma up to temperatures of a few million degrees. In some cases, the shocked features appear to be stationary. They are interpreted as shock diamonds. We aim at investigating the physics that guides the formation of X-ray emitting stationary shocks in protostellar jets, the role of the magnetic field in determining the location, stability, and detectability in X-rays of these shocks, and the physical properties of the shocked plasma. We performed a set of 2.5-dimensional magnetohydrodynamic numerical simulations modelling supersonic jets ramming into a magnetized medium and explored different configurations of the magnetic field. The model takes into account the most relevant physical effects, namely thermal conduction and radiative losses. We compared the model results with observations, via the emission measure and the X-ray luminosity synthesized from the simulations. Our model explains the formation of X-ray emitting stationary shocks in a natural way. The magnetic field collimates the plasma at the base of the jet and forms there a magnetic nozzle. After an initial transient, the nozzle leads to the formation of a shock diamond at its exit which is stationary over the time covered by the simulations (~ 40 - 60 yr; comparable with time scales of the observations). The shock generates a point-like X-ray source located close to the base of the jet with luminosity comparable with that inferred from X-ray observations of protostellar jets. For the range of parameters explored, the evolution of the post-shock plasma is dominated by the radiative cooling, whereas the thermal conduction slightly affects the structure of the shock.Comment: Accepted for publication in Astronomy and Astrophysic

Is Seasonal Households' Consumption Good for the Nexus Carbon/Water Footprint? the Spanish Fruits and Vegetables Case

Proximity and in-season consumption criteria have been suggested as solutions for fruits and vegetables consumers to drive the economy to a more sustainable development. Using a new concept, seasonal avoided footprint by imports, we disentangle the role of period and country of origin. Although, as a general rule, consumers could reduce the footprint by choosing domestic produce, this is not always the case. Due to the high efficiency of Spanish domestic production in terms of both CO2e and water use (except for scarce water), imports from some regions, like Africa (green beans, peppers, tomatoes, bananas, strawberries, oranges), contribute to significantly increasing both water and carbon impacts. However, a monthly basis analysis shows unsustainable hotspots for domestic production. Importing from France (apples, potatoes) or Portugal (tomatoes, strawberries) reduces both footprints, so Spanish local consumption would be bad for the environment. Hotspots are mainly concentrated in scarce water and, especially, for out-of-season vegetables during 11 months a year (savings up to 389%), nine months for out-of-season fruits, and five months for in-season fruits. The results suggest the difficulty to generalize an easy environmental recommendation based on buying local fruits and vegetables: consumption must be analyzed on monthly/seasonal, product, and country bases

Peer-to-Peer accommodation in rural areas of Catalonia: defining typologies of rural municipalities

This paper presents findings relating to the territorial processes underlying the distribution and location of P2P accommodation in rural parts of Catalonia by establishing a system for classifying rural municipalities based on the volume and growth rate of the supply of this tourist accommodation, its share of the total supply of tourist accommodation, the pressure on the local population, and the function of this supply of accommodation in the regional tourism context. According to the findings, there are three distinct types of rural municipality: (a) Rural municipalities where the volume and growth of the supply of this accommodation are striking, these municipalities are located in the coastal hinterland and in high mountain areas, both of which enjoy high levels of tourism. This supply of accommodation plays a key role in the expansion of the areas of influence of well-established tourist destinations, (b) rural municipalities where this supply of accommodation presents an average volume and growth rate, located in inland areas of Catalonia and in high mountain regions with non-mass tourism development models specializing in rural tourism. This supply is helping boost tourism by expanding and diversifying the range of accommodation, and (c) rural municipalities where no tourist accommodation was available before the arrival of P2P accommodation. These are municipalities in inland areas with a strong agricultural presence, where P2P accommodation is paving the way for tourism

Polarized microwave emission from space particles in the upper atmosphere of the Earth

Tons of space particles enter the Earth atmosphere every year, being detected when they produce fireballs, meteor showers, or when they impact the Earth surface. Particle detection in the showers could also be attempted from space using satellites in low Earth orbit. Measuring the polarization would provide extra crucial information on the dominant alignment mechanisms and the properties of the meteor families. In this article, we evaluate the expected signal to aid in the design of space probes for this purpose. We have used the RADMC-3D code to simulate the polarized microwave emission of aligned dust particles with different compositions: silicates, carbonates and irons. We have assumed a constant spatial particle density distribution of 0.22 cm$^{-3}$, based on particle density measurements carried during meteor showers. Four different grain size distributions with power indices ranging from $-3.5$ to $-2.0$ and dust particles with radius ranging from 0.01 $\mathrm{\mu}$m to 1 cm have been considered for the simulations. Silicates and carbonates align their minor axis with the direction of the solar radiation field; during the flight time into the Earth atmosphere, iron grains get oriented with the Earth's magnetic field depending on their size. Alignment direction is reflected in the $Q$-Stokes parameter and in the polarization variation along the orbit. Polarization depends on the composition and on the size distribution of the particles. The simulations show that some specific particle populations might be detectable even with a small probe equipped with high sensitivity, photon-counting microwave detectors operating in low Earth orbit

Edat de casament i celibat definitiu a la Catalunya Central (1803-1807)

A partir de las respuestas de los rectores de las parroquias del Obispado de Vic entre 1803 y 1807, los autores reconstruyen el comportamiento demográfico de la nupcialidad y el celibato en los diferentes grupos socioprofesionales de la Catalunya central.By analyzing the answers of the rectors of the parrishes in the Bishopric of Vic benveen 1803 and 1807, the authors rebuild the demographic behaviour of the nuptiality and celibacy rates in the different socioprofessional groups in central Catalunya

Electrodeposited Ni-rich Ni-Pt mesoporous nanowires for selective and efficient formic acid-assisted hydrogenation of levulinic acid to γ-valerolactone

In pursuit of friendlier conditions for the preparation of high-value biochemicals, we developed a catalytic synthesis of -valerolactone by levulinic acid hydrogenation with formic acid as the hydrogen source. Both levulinic and formic acid are intermediate products in the biomass transformation processes. The objective of the work is two-fold; development of a novel approach for milder synthesis conditions to produce -valerolactone and the reduction of the economic cost of the catalyst. Ni-rich Ni-Pt mesoporous nanowires were synthesized in an aqueous medium using a combined hard-soft template-assisted electrodeposition method, in which porous polycarbonate membranes controlled the shape, and the pluronic P-123 copolymer served as the porogen agent. The electrodeposition conditions selected favored nickel deposition and generated nanowires with nickel percentages above the 75 at. %. The increase in deposition potential favored nickel deposition. However, it was detrimental for the porous diameter, because the mesoporous structure is promoted by the presence of the platinum-rich micelles near the substrate, which is not favored at the more negative potentials. The prepared catalysts promoted the complete transformation to -valerolactone in a yield of around 99% and proceeded with the absence of by-products. The couple temperature and reaction time were optimized considering the energy cost. The threshold operational temperature was established at 140 ºC, at which, 120 minutes were sufficient for attaining the complete transformation. Working temperatures below 140 ºC rendered the reaction completion difficult. The Ni78Pt22 nanowires exhibited excellent reusability, with minimal nickel leaching into the reaction mixture, whereas those with higher nickel contents showed corrosion