316 research outputs found

    Differential Functional Constraints Cause Strain-Level Endemism in Polynucleobacter Populations.

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    The adaptation of bacterial lineages to local environmental conditions creates the potential for broader genotypic diversity within a species, which can enable a species to dominate across ecological gradients because of niche flexibility. The genus Polynucleobacter maintains both free-living and symbiotic ecotypes and maintains an apparently ubiquitous distribution in freshwater ecosystems. Subspecies-level resolution supplemented with metagenome-derived genotype analysis revealed that differential functional constraints, not geographic distance, produce and maintain strain-level genetic conservation in Polynucleobacter populations across three geographically proximal riverine environments. Genes associated with cofactor biosynthesis and one-carbon metabolism showed habitat specificity, and protein-coding genes of unknown function and membrane transport proteins were under positive selection across each habitat. Characterized by different median ratios of nonsynonymous to synonymous evolutionary changes (dN/dS ratios) and a limited but statistically significant negative correlation between the dN/dS ratio and codon usage bias between habitats, the free-living and core genotypes were observed to be evolving under strong purifying selection pressure. Highlighting the potential role of genetic adaptation to the local environment, the two-component system protein-coding genes were highly stable (dN/dS ratio, < 0.03). These results suggest that despite the impact of the habitat on genetic diversity, and hence niche partition, strong environmental selection pressure maintains a conserved core genome for Polynucleobacter populations. IMPORTANCE Understanding the biological factors influencing habitat-wide genetic endemism is important for explaining observed biogeographic patterns. Polynucleobacter is a genus of bacteria that seems to have found a way to colonize myriad freshwater ecosystems and by doing so has become one of the most abundant bacteria in these environments. We sequenced metagenomes from locations across the Chicago River system and assembled Polynucleobacter genomes from different sites and compared how the nucleotide composition, gene codon usage, and the ratio of synonymous (codes for the same amino acid) to nonsynonymous (codes for a different amino acid) mutations varied across these population genomes at each site. The environmental pressures at each site drove purifying selection for functional traits that maintained a streamlined core genome across the Chicago River Polynucleobacter population while allowing for site-specific genomic adaptation. These adaptations enable Polynucleobacter to become dominant across different riverine environmental gradients

    Impact of Bi2O3 modifier concentration on barium–zincborate glasses: physical, structural, elastic, and radiation-shielding properties

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    Abstract: A sequence of Bi2O3 varying barium–zincborate (BZX) glasses with the chemical composition (60-x) B2O3-20ZnO-20BaCO3-xBi2O3-0.5Dy2O3 (where x = 0, 5, 10, 15, 20, 25, and 30 in wt%) is fabricated by melt-quenching method. The fabricated samples were examined for the variation in physical, structural, elastic, and radiation-shielding properties with the Bi2O3 concentration. The structural and compositional evaluations are done using XRD and FTIR spectra. The BZX matrixes consist of the trigonal-planar and tetrahedral groups of borates, BiO3 and BiO6 units of Bi2O3, and the non-bridging oxygen in general. The average single-bond strength values substantiate the increasing ionic nature of the BZX glasses. The variation in the density and molar volume of the BZX series discussed in terms of various structural and elastic properties. The glass-coded BZ15 was found to be the best candidate for the sound-resistant applications based on the atomic packing fraction and the acoustic impedance studies. With MCNP5 simulation, the mass attenuation coefficient (MAC) values of all the samples were calculated and compared with a theoretical approach using the XCOM program. As the amount of Bi2O3 increases, the linear attenuation coefficient (LAC) increases with it at all energies. The LAC values varied between 0.2805 and 0.5269 cm−1 for the investigated glasses at 0.81 MeV. BZ30 glass is the more effective shield due to the highest MAC and LAC values. Graphic abstract: [Figure not available: see fulltext.]. © 2021, The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature

    Parabolic Trough Solar Collector – Design, Construction and Testing

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    This paper presents the design, construction and investigates an experimental study of a parabolic Trough Solar Collector (PTSC). It is constructed of multi – piece glass mirror to form the parabolic reflector (1.8 m ? 2.8 m) its form were checked with help of a laser and carbon steel rectangular as receiver. Sun tracker has been developed (using two – axis) to track solar PTSC according to the direction of beam propagation of solar radiation. Using synthetic oil as a heat transfer its capability to heat transfer and load high temperature (?400 oc). The storage tank is fabricated with stainless steel of size 50 L. The experimental tests have been carried out in Baghdad climatic conditions (33.3o N, 44.4o E) during selective days of the months October and November. The performance of PTSC is evaluated using outdoor experimental measurements including the useful heat gain, the thermal instantaneous efficiency and the energy gained by the storage tank oil. The storage tank oil temperature is increased from 30oc at 9:30h to 136oc at 13:30h without draw – off oil. The experimental result shows the average thermal efficiency was 42% which is fairly acceptable assessment results of a PTSC locally

    Surface acoustic waves induced micropatterning of cells in gelatin methacryloyl (GelMA) hydrogels

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    Acoustic force patterning is an emerging technology that provides a platform to control the spatial location of cells in a rapid, accurate, yet contactless manner. However, very few studies have been reported on the usage of acoustic force patterning for the rapid arrangement of biological objects, such as cells, in a three-dimensional (3D) environment. In this study, we report on a bio-acoustic force patterning technique, which uses surface acoustic waves (SAWs) for the rapid arrangement of cells within an extracellular matrix-based hydrogel such as gelatin methacryloyl (GelMA). A proof-of-principle was achieved through both simulations and experiments based on the in-house fabricated piezoelectric SAW transducers, which enabled us to explore the effects of various parameters on the performance of the built construct. The SAWs were applied in a fashion that generated standing SAWs (SSAWs) on the substrate, the energy of which subsequently was transferred into the gel, creating a rapid, and contactless alignment of the cells (<10 s, based on the experimental conditions). Following ultraviolet radiation induced photo-crosslinking of the cell encapsulated GelMA pre-polymer solution, the patterned cardiac cells readily spread after alignment in the GelMA hydrogel and demonstrated beating activity in 5-7 days. The described acoustic force assembly method can be utilized not only to control the spatial distribution of the cells inside a 3D construct, but can also preserve the viability and functionality of the patterned cells (e.g. beating rates of cardiac cells). This platform can be potentially employed in a diverse range of applications, whether it is for tissue engineering, in vitro cell studies, or creating 3D biomimetic tissue structures

    Selected Indicators of Al-Najaf Road Network: Public Transportation Noise and Pollution

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    It is urgently necessary to improve the state of transportation and related infrastructure, especially given that the most important indicators of urban development gauge a city's progress. One of the most influential of these indicators is what is known as "smart transport, " which refers to transportation that utilizes modern communication and information technology technologies to address various challenges in various transportation sectors. The holy city of Najaf smart transportation strategy seeks to reduce dangerous levels of traffic-related noise and air pollution while enhancing various aspects of mobility and traffic flow indicators. This study aims to evaluate the performance of the existing traffic network and public transport in Najaf City and its interference with noise and air pollution at selected points for data gathering by using field measurements using cameras, noise meters, and pollution measurement devices. The study states that the public transport sector in Al-Najaf city is significantly poor as private cars are dominant by about 65% of traffic mix with values of pollution and noise above the standards. One of the most effective solutions to traffic problems is the implementation of intelligent transportation systems. Part of these strategies is establishing a tram network and raising road classes’ strategies by proposing some geometric design editing, U-turns reducing, and raised ramps additions

    Design and Gamma-Ray Attenuation Features of New Concrete Materials for Low- and Moderate-Photons Energy Protection Applications

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    We aimed, in this investigation, to prepare novel concretes which can be used in gamma-ray shielding applications. The experimental approach was performed using a NaI (Tl) detector to measure the concrete’s shielding features for different energies, ranging from 0.081 MeV to 1.408 MeV. The density of the fabricated concretes decreased with increasing W/C ratio, where the density decreased by 2.680 g/cm3, 2.614 g/cm3, and 2.564 g/cm3 for concretes A, B, and C, respectively, with increases in the W/C ratio of 0.4, 0.6, and 0.8, respectively. When the energy was elevated between 0.08 MeV and 1.408 MeV, the highest values were attained for concrete A, with values ranging between 0.451 cm−1 and 0.179 cm−1. The lowest half-value layer (Δ0.5) values were achieved for concrete C, where the Δ0.5 values varied between 1.53 cm and 3.86 cm between 0.08 MeV and 1.408 MeV. The highest Δ0.5 values were achieved for concrete A, where the Δ0.5 varied between 1.77 cm and 4.67 cm between 0.08 MeV and 1.408 MeV. According to this investigation, concrete A has the highest promise in radiation shielding purposes because it has the most desirable properties of the concretes studied. © 2022 by the authors.Princess Nourah Bint Abdulrahman University, PNU: PNURSP2022R57The authors express their gratitude to Princess Nourah bint Abdulrahman University Researchers Supporting Project number (PNURSP2022R57), Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia
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