3,642 research outputs found
From Organic Wastes and Hydrocarbons Pollutants to Polyhydroxyalkanoates: Bioconversion by Terrestrial and Marine Bacteria
The use of fossil-based plastics has become unsustainable because of the polluting production processes, difficulties for waste management sectors, and high environmental impact. Polyhydroxyalkanoates (PHA) are bio-based biodegradable polymers derived from renewable resources and synthesized by bacteria as intracellular energy and carbon storage materials under nutrients or oxygen limitation and through the optimization of cultivation conditions with both pure and mixed culture systems. The PHA properties are affected by the same principles of oil-derived polyolefins, with a broad range of compositions, due to the incorporation of different monomers into the polymer matrix. As a consequence, the properties of such materials are represented by a broad range depending on tunable PHA composition. Producing waste-derived PHA is technically feasible with mixed microbial cultures (MMC), since no sterilization is required; this technology may represent a solution for waste treatment and valorization, and it has recently been developed at the pilot scale level with different process configurations where aerobic microorganisms are usually subjected to a dynamic feeding regime for their selection and to a high organic load for the intracellular accumulation of PHA. In this review, we report on studies on terrestrial and marine bacteria PHA-producers. The available knowledge on PHA production from the use of different kinds of organic wastes, and otherwise, petroleum-polluted natural matrices coupling bioremediation treatment has been explored. The advancements in these areas have been significant; they generally concern the terrestrial environment, where pilot and industrial processes are already established. Recently, marine bacteria have also offered interesting perspectives due to their advantageous effects on production practices, which they can relieve several constraints. Studies on the use of hydrocarbons as carbon sources offer evidence for the feasibility of the bioconversion of fossil-derived plastics into bioplastics
Listening to the sound of dark sector interactions with gravitational wave standard sirens
We consider two stable Interacting Dark Matter -- Dark Energy models and
confront them against current Cosmic Microwave Background data from the
\textit{Planck} satellite. We then generate luminosity distance measurements
from mock Gravitational Wave events matching the expected
sensitivity of the proposed Einstein Telescope. We use these to forecast how
the addition of Gravitational Wave standard sirens data can improve current
limits on the Dark Matter -- Dark Energy coupling strength (). We find
that the addition of Gravitational Waves data can reduce the current
uncertainty by a factor of . Moreover, if the underlying cosmological model
truly features Dark Matter -- Dark Energy interactions with a value of
within the currently allowed upper limit, the addition of
Gravitational Wave data would help disentangle such an interaction from the
standard case of no interaction at a significance of more than .Comment: 16 pages, 3 tables, 4 figures; version published in JCA
Editorial: Biofuels and Bioproducts From Anaerobic Processes: Anaerobic Membrane Bioreactors (AnMBRs)
New biodegradable waste treatment configurations and technologies have arisen to support the transition of treatment plants toward resource recovery facilities. The interest in Anaerobic Membrane Biological Reactor (AnMBR) technology is increasing due to the advantages related to combine anaerobic digestion with membrane filtration. Thanks to the complete retention of anaerobic microorganisms, AnMBRs have the capacity to efficiently recover most of the energy potential in biodegradable waste streams in the form of biogas and produce high-quality effluents with low biomass production
Specific Microbial Communities Are Selected in Minimally-Processed Fruit and Vegetables according to the Type of Product
Fruits and vegetables (F&V) products are recommended for the daily diet due to their low caloric content, high amount of vitamins, minerals and fiber. Furthermore, these foods are a source of various phytochemical compounds, such as polyphenols, flavonoids and sterols, exerting antioxidant activity. Despite the benefits derived from eating raw F&V, the quality and safety of these products may represent a source of concern, since they can be quickly spoiled and have a very short shelf-life. Moreover, they may be a vehicle of pathogenic microorganisms. This study aims to evaluate the bacterial and fungal populations in F&V products (i.e., iceberg lettuces, arugula, spinaches, fennels, tomatoes and pears) by using culture-dependent microbiological analysis and high-throughput sequencing (HTS), in order to decipher the microbial populations that characterize minimally-processed F&V. Our results show that F&V harbor diverse and product-specific bacterial and fungal communities, with vegetables leaf morphology and type of edible fraction of fruits exerting the highest influence. In addition, we observed that several alterative (e.g., Pseudomonas and Aspergillus) and potentially pathogenic taxa (such as Staphylococcus and Cladosporium) are present, thus emphasizing the need for novel product-specific strategies to control the microbial composition of F&V and extend their shelf-life
Exact Correlation Functions in the Brownian Loop Soup
We compute analytically and in closed form the four-point correlation
function in the plane, and the two-point correlation function in the upper
half-plane, of layering vertex operators in the two dimensional conformally
invariant system known as the Brownian Loop Soup. These correlation functions
depend on multiple continuous parameters: the insertion points of the
operators, the intensity of the soup, and the charges of the operators. In the
case of the four-point function there is non-trivial dependence on five
continuous parameters: the cross-ratio, the intensity, and three real charges.
The four-point function is crossing symmetric. We analyze its conformal block
expansion and discover a previously unknown set of new conformal primary
operators.Comment: 28 pages, 2 figures; Eq. (20) correcte
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