68 research outputs found

    Medium-Induced Modification of Z-Tagged Charged Particle Yields in Pb+Pb Collisions at 5.02 TeV with the ATLAS Detector

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    The yield of charged particles opposite to a Z boson with large transverse momentum ( p T ) is measured in 260     pb − 1 of p p and 1.7     nb − 1 of Pb + Pb collision data at 5.02 TeV per nucleon pair recorded with the ATLAS detector at the Large Hadron Collider. The Z boson tag is used to select hard-scattered partons with specific kinematics, and to observe how their showers are modified as they propagate through the quark-gluon plasma created in Pb + Pb collisions. Compared with p p collisions, charged-particle yields in Pb + Pb collisions show significant modifications as a function of charged-particle p T in a way that depends on event centrality and Z boson p T . The data are compared with a variety of theoretical calculations and provide new information about the medium-induced energy loss of partons in a p T regime difficult to measure through other channels

    Search for pair production of third-generation scalar leptoquarks decaying into a top quark and a τ-lepton in pp collisions at s√ = 13 TeV with the ATLAS detector

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    A search for pair production of third-generation scalar leptoquarks decaying into a top quark and a τ-lepton is presented. The search is based on a dataset of pp collisions at s√ = 13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb−1. Events are selected if they have one light lepton (electron or muon) and at least one hadronically decaying τ -lepton, or at least two light leptons. In addition, two or more jets, at least one of which must be identified as containing b-hadrons, are required. Six final states, defined by the multiplicity and flavour of lepton candidates, are considered in the analysis. Each of them is split into multiple event categories to simultaneously search for the signal and constrain several leading backgrounds. The signal-rich event categories require at least one hadronically decaying τ-lepton candidate and exploit the presence of energetic final-state objects, which is characteristic of signal events. No significant excess above the Standard Model expectation is observed in any of the considered event categories, and 95% CL upper limits are set on the production cross section as a function of the leptoquark mass, for different assumptions about the branching fractions into tτ and bν. Scalar leptoquarks decaying exclusively into tτ are excluded up to masses of 1.43 TeV while, for a branching fraction of 50% into tτ, the lower mass limit is 1.22 TeV

    Photobioreactors as potential tools for environmentally friendly and sustainable buildings

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    Global warming is a critical risk for the balance of nature, and its effects are increasing due to gases like CO2. One approach for CO2 capture is bringing together microalgae and buildings in esthetic bio-facade systems for obtaining environmentally friendly benefits. The aim of this study is to investigate the microalgae photobioreactors (PBR) as a potential bio-facade unit. Bio-facade concept focused on the multiple uses of water and nutrients, as well as CO2 capture, to highlight the sustainability and practicality. Chlorella vulgaris is selected as a model microalga due to its low doubling time and high biomass productivity. Experiments covered the dilutions of microalga medium (10%, 20%, 40%, 80%), recycling the cell separated medium and addition of CO2-enriched air (5% and 10%) focusing on their effects on various key factors like biomass and photosynthetic activity. PBR integrated laboratory scale house unit has also been constructed lastly. According to the preliminary results, up to 80% dilution, up to three cycles of medium and 5% CO2-enriched environment provided the high level of activity for bio-facade system. Interior air quality, changing of temperature and amounts of CO2-O-2 with increasing of the biomass were investigated in PBR integrated laboratory scale house unit which depended on the outcomes of preliminary experiments (20% dilution and 5% CO2-enriched air). The results of unit showed the positive effects of the microalga integration with regards to its capability as a biofilter and a biocurtain for the sustainability. [GRAPHICS]

    Microalgae pigments as a sustainable approach to textile dyeing: A critical review

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    Microalgae derived pigments, such as phycobiliproteins, chlorophylls, and carotenoids, offer eco-friendly al-ternatives to synthetic dyes. These pigments are known for their vibrant colors, as well as their antimicrobial, antioxidative, and UV protective properties, making them commonly used in the food, pharmaceutical, and cosmetic industries. Recently, they have also gained attention in the textile dyeing industry. Compared to other natural dye sources like plants, bacteria, and fungi, microalgae pigments possess significant potential as natural textile dyes. They exhibit high pigment productivity, more sustainable production systems, current industrial-scale production, and a lack of seasonal dependency. This review aims to provide an overview of the current state, limitations, and future prospects regarding the utilization of microalgae pigments as textile dyes. The report emphasizes the commercial availability of microalgae pigments, highlights current studies exploring their dyeing potential on various textile materials, and discusses the development techniques aimed at enhancing dyeing performance. This emerging and promising research field has the potential to revolutionize the pro-duction of eco-friendly and sustainable textile products, while also contributing to a reduction in the use of synthetic dyes in the textile industry

    Computational fluid dynamics modelling of stirred tank photobioreactor for Haematococcus pluvialis production: Hydrodynamics and mixing conditions

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    Agitated photobioreactors (PBR) have been widespread for the cultivation of microalgae because of their advantages in mixing and mass transfer conditions. However, it is difficult to investigate the behaviors of cultivation broth flow with experimental procedures in these PBRs. Computational Fluid Dynamics (CFD) is a common method that has been used to simulate the performance of fluid containing systems in order to investigate the fluid flow, reduce the design cost and improve the efficiency. The objective of this study was to evaluate hydrodynamics and mixing conditions of stirred tank PBR for Haematococcus pluvialis production experimentally and numerically. The cells were first cultivated in a stirred tank PBR containing Rushton turbine impeller and the cell growth was examined during 10 days. At the end of cultivation, the cell concentration was reached the value of 3.1 +/- 0.1 x 10(5) cells mL(-1) with the total carotenoid content of 2.47 +/- 0.01 mg L-1. Then, the hydrodynamic analyses were conducted to evaluate the average velocity magnitude, turbulence properties and dead zone inside the PBR. The simulation results obtained from realizable k-epsilon turbulence model showed that the uniformity index of average velocity was found as 0.86. This result showed that the fluid flow showed similar behavior in the most parts of PBR except around the impellers. The velocity contours supported that the mixing conditions were supplied efficiently, however the vortex formation was observed around the impellers in spite of the baffles. In addition, the turbulence kinetic energy having a vital influence on mixing characteristics was found between the values of 1.0 x 10(-2) and 3.0 x 10(-2) m(2) s(-2) and the lowest values were observed between two impellers due to extent of mixing. Obtained results could be used to re-design PBR configurations considering the impeller type, the distance between impellers and cultivation conditions
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