An astonishing diversity of microorganisms thrives on our planet and their activities are fundamental for the functioning of all ecosystems including the human body. Consequently, detailed insights ...into the functions performed by microorganisms in their natural environment are required to understand human biology and the biology of the world around us and to lay the foundations for targeted manipulation of microbial communities. Isotope-labeling techniques combined with molecular detection tools are frequently used by microbial ecologists to directly link structure and function of microbial communities and to monitor metabolic properties of uncultured microbes at the single-cell level. However, only the recent combination of such techniques with Raman microspectroscopy or secondary ion mass spectrometry enables functional studies of microbes on a single-cell level by using stable isotopes as labels. This review provides an overview of these new techniques and their applications in microbial ecology, which allow us to investigate the ecophysiology of uncultured microbes to an extent that was unimaginable just a few years ago.
•A novel tool for CSP tower solar field layout and characterization is presented.•Rapid layout assessment is achieved using a truncated Hermite series flux density model.•Algorithms developed to ...improve speed, accuracy, and flexibility are described.
This paper develops and demonstrates a new SolarPower tower Integrated Layout and Optimization Tool (SolarPILOT). The tool uses the analytical flux image Hermite series approximation originally implemented in the DELSOL3 software developed by Sandia National Laboratory in the early 1980s. By applying the analytical model to individual heliostat images rather than large groups or zones of heliostats, SolarPILOT can characterize a wide variety of heliostat field layouts. The individual heliostat modeling approach increases computational expense in comparison with DELSOL3, so SolarPILOT implements a number of improvements to the analytical approximation method to improve model accuracy and computational efficiency. This paper discusses several of these methods, including dynamic heliostat grouping to reduce the expense of intercept factor evaluation, approximation of annual productivity with a subset of time steps throughout the year, polygon clipping to accurately calculate inter-heliostat shadowing and blocking, receiver and tower geometry optimization, and a trigonometric image transformation technique that ensures model accuracy for small heliostats. SolarPILOT also integrates a Monte-Carlo ray tracing engine (SolTrace), providing improved receiver optical modeling capability, a user-friendly front end for geometry definition, and side-by-side validation of the analytical algorithms.
Nitrite-oxidizing bacteria (NOB) catalyze the second step of nitrification, nitrite oxidation to nitrate, which is an important process of the biogeochemical nitrogen cycle. NOB were traditionally ...perceived as physiologically restricted organisms and were less intensively studied than other nitrogen-cycling microorganisms. This picture is in contrast to new discoveries of an unexpected high diversity of mostly uncultured NOB and a great physiological versatility, which includes complex microbe–microbe interactions and lifestyles outside the nitrogen cycle. Most surprisingly, close relatives to NOB perform complete nitrification (ammonia oxidation to nitrate) and this finding will have far-reaching implications for nitrification research. We review recent work that has changed our perspective on NOB and provides a new basis for future studies on these enigmatic organisms.
The earth contains a huge number of largely uncharacterized Bacteria and Archaea. Microbiologists are struggling to summarize their genetic diversity and classify them, which has resulted in heated ...debates on methods for defining species, mechanisms that lead to speciation and whether microbial species even exist. This Review proposes that decisions on the existence of species and methods to define them should be guided by a method-free species concept that is based on cohesive evolutionary forces. It summarizes current approaches to defining species and the problems of these approaches, and presents selected examples of the population genetic patterns at and below the species level.
Abstract
The problem of a misinformed citizenry is often used to motivate research on misinformation and its corrections. However, researchers know little about how differences in informedness affect ...how well corrective information helps individuals develop knowledge about current events. We introduce a Differential Informedness Model that distinguishes between three types of individuals, that is, the uninformed, the ambiguous, and the misinformed, and establish their differences with two experiments incorporating multiple partisan cues and issues. Contrary to the common impression, the U.S. public is largely uninformed rather than misinformed of a wide range of factual claims verified by journalists. Importantly, we find that the success of belief updating after exposure to corrective information (via a fact-checking article) is dependent on the presence, the certainty, and the accuracy of one’s prior belief. Uninformed individuals are more likely to update their beliefs than misinformed individuals after exposure to corrective information. Interestingly, the ambiguous individuals, regardless of whether their uncertain guesses were correct, do not differ from uninformed individuals with respect to belief updating.
Graphitic carbon nitride (g-C3N4) has recently emerged as a promising visible-light-responsive polymeric photocatalyst; however, a molecular-level understanding of material properties and its ...application for water purification were underexplored. In this study, we rationally designed nonmetal doped, supramolecule-based g-C3N4 with improved surface area and charge separation. Density functional theory (DFT) simulations indicated that carbon-doped g-C3N4 showed a thermodynamically stable structure, promoted charge separation, and had suitable energy levels of conduction and valence bands for photocatalytic oxidation compared to phosphorus-doped g-C3N4. The optimized carbon-doped, supramolecule-based g-C3N4 showed a reaction rate enhancement of 2.3–10.5-fold for the degradation of phenol and persistent organic micropollutants compared to that of conventional, melamine-based g-C3N4 in a model buffer system under the irradiation of simulated visible sunlight. Carbon-doping but not phosphorus-doping improved reactivity for contaminant degradation in agreement with DFT simulation results. Selective contaminant degradation was observed on g-C3N4, likely due to differences in reactive oxygen species production and/or contaminant-photocatalyst interfacial interactions on different g-C3N4 samples. Moreover, g-C3N4 is a robust photocatalyst for contaminant degradation in raw natural water and (partially) treated water and wastewater. In summary, DFT simulations are a viable tool to predict photocatalyst properties and oxidation performance for contaminant removal, and they guide the rational design, fabrication, and implementation of visible-light-responsive g-C3N4 for efficient, robust, and sustainable water treatment.
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