bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metallotherapeutics development in the age of iron-clad bacteria
Authors: Centola Garrick , Xue Fengtian , Wilks Angela 
Published: November 2020

Abstract
Drug-resistant infections pose a significant risk to global health as pathogenic bacteria become increasingly difficult to treat. The rapid selection of resistant strains through poor antibiotic stewardship has reduced the number of viable treatments and increased morbidity of infections, especially among the immunocompromised. To circumvent such challenges, new strategies are required to stay ahead of emerging resistance trends, yet research and funding for antibiotic development lags other classes of therapeutics. Though the use of metals in therapeutics has been around for centuries, recent strategies have devoted a great deal of effort into the pathways through which bacteria acquire and utilize iron, which is critical for the establishment of infection. To target iron uptake systems, siderophore–drug conjugates have been developed that hijack siderophore-based iron uptake for delivery of antibiotics. While this strategy has produced several potential leads, the use of siderophores in infection is diminished over time when bacteria adapt to utilize heme as an iron source, leading to a need for the development of porphyrin mimetics as therapeutics. The use of such strategies as well as the inclusion of gallium, a redox-inert iron mimic, are herein reviewed.
Tidally perturbed pulsations in the pre-main sequence δ Scuti binary RS Cha
Authors: Steindl T. , Zwintz K. , Bowman D. M. 
Published: November 2020

Context. Stellar components in binaries are subject to tidal forces which influence asteroseismic properties. Tidally pertubed pulsations have been reported for different objects but none of these are in their pre-main sequence phase of evolution. This makes RS Cha, consisting of two δ Scuti stars and with pulsational characteristics influenced by tidal effects, the first such object observed.
Aims. We aim to investigate the pulsational properties of the eclipsing binary RS Cha in terms of the theory of tidally perturbed pulsations.
Methods. Based on photometric time series obtained from the TESS satellite, we performed binary modelling using PHOEBE to interpret the binary light curve and to allow the investigation of the pulsations of both components in RS Cha. We modelled the detrended light curve with the superposition of linear modes. The frequencies were then interpreted as self excited modes perturbed by tidal forces.
Results. We find evidence for tidally perturbed modes, which enables the identification of pulsation modes. RS Cha mainly exhibits dipole modes, while one prominent l = 2 or l = 3 mode is also inferred. The latter verifies previous results from spectroscopic time series.
Conclusion. This work shows that RS Cha is an ideal candidate to test the theory of tidally perturbed pulsations within the framework of asteroseismic modelling. The identification of multiple pulsation modes using this theory is unprecedented and will be a keystone in the future of pre-main sequence asteroseismology. However, amplitude modulation caused by the changing light ratio during the orbital phase in an eclipsing binary also plays a significant role, which can complicate mode identification.
Polarisation properties of methanol masers
Authors: Dall’Olio D. , Vlemmings W. H. T. , Lankhaar B. , Surcis G. 
Published: November 2020

Context. Astronomical masers have been effective tools in the study of magnetic fields for years. Observations of the linear and circular polarisation of different maser species allow for the determination of magnetic field properties, such as morphology and strength. In particular, methanol can be used to probe different parts of protostars, such as accretion discs and outflows, since it produces one of the strongest and the most commonly observed masers in massive star-forming regions.
Aims. We investigate the polarisation properties of selected methanol maser transitions in light of newly calculated methanol Landé g-factors and in consideration of hyperfine components. We compare our results with previous observations and evaluate the effect of preferred hyperfine pumping and non-Zeeman effects.
Methods. We ran simulations using the radiative transfer code, CHAMP, for different magnetic field values, hyperfine components, and pumping efficiencies.
Results. We find a dependence between the linear polarisation fraction and the magnetic field strength as well as the hyperfine transitions. The circular polarisation fraction also shows a dependence on the hyperfine transitions. Preferred hyperfine pumping can explain some high levels of linear and circular polarisation and some of the peculiar features seen in the S-shape of observed V-profiles. By comparing a number of methanol maser observations taken from the literature with our simulations, we find that the observed methanol masers are not significantly affected by non-Zeeman effects related to the competition between stimulated emission rates and Zeeman rates, such as the rotation of the symmetry axis. We also consider the relevance of other non-Zeeman effects that are likely to be at work for modest saturation levels, such as the effect of magnetic field changes along the maser path and anisotropic resonant scattering.
Conclusions. Our models show that for methanol maser emission, both the linear and circular polarisation percentages depend on which hyperfine transition is masing and the degree to which it is being pumped. Since non-Zeeman effects become more relevant at high values of brightness temperatures, it is important to obtain good estimates of these quantities and the maser beaming angles. Better constraints on the brightness temperature will help improve our understanding of the extent to which non-Zeeman effects contribute to the observed polarisation percentages. In order to detect separate hyperfine components, an intrinsic thermal line width that is significantly smaller than the hyperfine separation is required.
Irradiation dose affects the composition of organic refractory materials in space
Authors: Urso R. G. , Vuitton V. , Danger G. , Le Sergeant d’Hendecourt L. , Flandinet L. , Djouadi Z. , Mivumbi O. , Orthous-Daunay F. R. , Ruf A. , Vinogradoff V. , Wolters C. , Brunetto R. 
Published: November 2020

Context. Near- and mid-infrared observations have revealed the presence of organic refractory materials in the Solar System, in cometary nuclei and on the surface of centaurs, Kuiper-belt and trans-neptunian objects. In these astrophysical environments, organic materials can be formed because of the interaction of frozen volatile compounds with cosmic rays and solar particles, and favoured by thermal processing. The analysis of laboratory analogues of such materials gives information on their properties, complementary to observations.
Aims. We present new experiments to contribute to the understanding of the chemical composition of organic refractory materials in space.
Methods. We bombard frozen water, methanol and ammonia mixtures with 40 keV H+ and we warmed the by-products up to 300 K. The experiments enabled the production of organic residues that we analysed by means of infrared spectroscopy and by very high resolution mass spectrometry to study their chemical composition and their high molecular diversity, including the presence of hexamethylenetetramine and its derivatives.
Results. We find that the accumulated irradiation dose plays a role in determining the composition of the residue.
Conclusions. Based on the laboratory doses, we estimate the astrophysical timescales to be short enough to induce an efficient formation of organic refractory materials at the surface of icy bodies in the outer Solar System.
Collisional ionisation, recombination, and ionisation potential in two-fluid slow-mode shocks: Analytical and numerical results
Authors: Snow B. , Hillier A. 
Published: November 2020

Context.Shocks are a universal feature of warm plasma environments, such as the lower solar atmosphere and molecular clouds, which consist of both ionised and neutral species. Including partial ionisation leads to the existence of a finite width for shocks, where the ionised and neutral species decouple and recouple. As such, drift velocities exist within the shock that lead to frictional heating between the two species, in addition to adiabatic temperature changes across the shock. The local temperature enhancements within the shock alter the recombination and ionisation rates and hence change the composition of the plasma.Aims.We study the role of collisional ionisation and recombination in slow-mode partially ionised shocks. In particular, we incorporate the ionisation potential energy loss and analyse the consequences of having a non-conservative energy equation.Methods.A semi-analytical approach is used to determine the possible equilibrium shock jumps for a two-fluid model with ionisation, recombination, ionisation potential, and arbitrary heating. Two-fluid numerical simulations are performed using the (PIP) code. Results are compared to the magnetohydrodynamic (MHD) model and the semi-analytic solution.Results.Accounting for ionisation, recombination, and ionisation potential significantly alters the behaviour of shocks in both substructure and post-shock regions. In particular, for a given temperature, equilibrium can only exist for specific densities due to the radiative losses needing to be balanced by the heating function. A consequence of the ionisation potential is that a compressional shock will lead to a reduction in temperature in the post-shock region, rather than the increase seen for MHD. The numerical simulations pair well with the derived analytic model for shock velocities.Conclusion.Multi-fluid effects can lead to a significant departure from MHD results. The results in this paper are applicable to a wide range of partially ionised plasmas, including the solar chromosphere and molecular clouds.
Solar geoengineering may not prevent strong warming from direct effects of CO
2
on stratocumulus cloud cover
Authors: Schneider Tapio , Kaul Colleen M. , Pressel Kyle G. 
Published: November 2020

Significance
Solar geoengineering that manipulates the amount of sunlight Earth absorbs is increasingly discussed as an option to counter global warming. However, we demonstrate that solar geoengineering is not a fail-safe option to prevent global warming because it does not mitigate risks to the climate system that arise from direct effects of greenhouse gases on cloud cover. High-resolution simulations of stratocumulus clouds show that clouds thin as greenhouse gases build up, even when warming is modest. In a scenario of solar geoengineering that is sustained for more than a century, this can eventually lead to breakup of the clouds, triggering strong (5°C), and possibly difficult to reverse, global warming, despite the solar geoengineering.
Consequences of seafood mislabeling for marine populations and fisheries management
Authors: Kroetz Kailin , Luque Gloria M. , Gephart Jessica A. , Jardine Sunny L. , Lee Patrick , Chicojay Moore Katrina , Cole Cassandra , Steinkruger Andrew , Donlan C. Josh 
Published: November 2020

Significance
The consumption of an important food source, seafood, has increased over the past half century. It is now the most globally traded food commodity and its supply chains are often complex and opaque. Contemporaneous with the growth of overall production, evidence of seafood product mislabeling has become ubiquitous. We show that enabling conditions exist for mislabeling to generate negative impacts on marine populations and to support consumption of products from poorly managed fisheries. More holistic approaches that include consumer and industry engagement, well-designed and targeted testing, and regulatory traceability programs could reduce seafood mislabeling and improve transparency related to impacts of seafood product consumption.
Hidden symmetries generate rigid folding mechanisms in periodic origami
Authors: McInerney James , Chen Bryan Gin-ge , Theran Louis , Santangelo Christian D. , Rocklin D. Zeb 
Published: November 2020

Significance
The traditional approach to designing origami metamaterials uses particular, highly symmetric crease patterns to generate folding motions for reconfigurability. We instead consider origami sheets with periodic but otherwise generic, asymmetric triangular faces and show they exhibit nonlinear folding motions which transform sheets through two-dimensional families of cylindrical configurations, with the addition of quadrilateral faces restricting sheets to one-dimensional subsets of configurations. This leads to a topological class of mechanical modes, preventing origami from exhibiting exponentially localized floppy modes observed in other systems. These results do not depend on scale or material and hence have applications extending to architecture and robotics, but particularly to the nanoscale, where limited control over fold patterns can constrain traditional techniques.
Thymus-derived B cell clones persist in the circulation after thymectomy in myasthenia gravis
Authors: Jiang Ruoyi , Hoehn Kenneth B. , Lee Casey S. , Pham Minh C. , Homer Robert J. , Detterbeck Frank C. , Aban Inmaculada , Jacobson Leslie , Vincent Angela , Nowak Richard J. , Kaminski Henry J. , Kleinstein Steven H. , O’Connor Kevin C. 
Published: November 2020

SignificanceMyasthenia gravis is caused by autoantibodies, which target postsynaptic proteins, primarily the acetylcholine receptor, that inhibit neuromuscular signaling. The myasthenia gravis thymus can serve as a reservoir of acetylcholine receptor-specific autoantibody-producing B cells. Thus, thymectomy is provided as a treatment. However, many patients fail to improve; the causes of poor responses are not understood. This investigation demonstrated that disease-associated B cell clones mature in the thymus before emigrating to the circulation. These B cell clones are present in the circulation after thymectomy and their persistence correlated with less favorable changes in clinical symptoms after thymectomy. This investigation provides mechanistic insight into the immunopathology associated with a diminished clinical response to thymectomy.
FMRP links optimal codons to mRNA stability in neurons
Authors: Shu Huan , Donnard Elisa , Liu Botao , Jung Suna , Wang Ruijia , Richter Joel D. 
Published: November 2020

Significance
Fragile X syndrome (FXS), the most prevalent monogenic form of autism, is caused by the loss of FMRP, an RNA binding protein. In the absence of FMRP, translation is dysregulated, but restoration of translational homeostasis rescues the syndrome and thus could suggest new treatments for the disorder. Using ribosome profiling and RNA metabolic profiling, we show that, in the FMRP-deficient mouse brain, there are few specific translational disturbances. Instead, there is widespread imbalance of RNA levels. This imbalance is caused by destabilization of the FMRP targets and other mRNAs based on codon optimality. Rebalancing the transcriptome may therefore be a key to correcting syndrome-related pathophysiologies. This study establishes a role for FMRP in linking codon optimality to RNA stability.
Hyperchromatic structural color for perceptually enhanced sensing by the naked eye
Authors: Talukdar Tahmid H. , McCoy Bria , Timmins Sarah K. , Khan Taufiquar , Ryckman Judson D. 
Published: November 2020

Significance
Modern scientific instrumentation and sensors are often bulky, expensive, and/or cumbersome to operate. Colorimetric sensors on the other hand offer a promising solution to these problems, as they can be analyzed with high spatiotemporal resolution by digital cameras or the naked eye. However, the performance of colorimetric sensors is typically inferior to the bulky/expensive alternatives as it can be difficult to convert small input stimulus variations into a large color response. This work introduces a means to address and overcome this problem and opens the door to types of high-performance colorimetric sensors, which are competitive with and/or offer greater functionality than the bulky/expensive alternatives.
Swimming microorganisms acquire optimal efficiency with multiple cilia
Authors: Omori Toshihiro , Ito Hiroaki , Ishikawa Takuji 
Published: November 2020

Significance
In this study, we clarified energetics of microbial locomotion by computing flow around a spherical swimmer covered with cilia. We showed a scaling law for microbial dynamics and revealed that microorganisms can swim optimally and enlarge their bodies by making multiple cilia. The optimal density of cilia was independent of the body size. Our estimated optimal density of cilia corresponded to those of actual microorganisms, including species of ciliates and microalgae. These results will help us to understand the mechanistic benefits of multiple cilia and open up an area of research that integrates fluid mechanics, biophysics, and microbiology.
Mercury isotopes identify near-surface marine mercury in deep-sea trench biota
Authors: Blum Joel D. , Drazen Jeffrey C. , Johnson Marcus W. , Popp Brian N. , Motta Laura C. , Jamieson Alan J. 
Published: November 2020

Significance
Mercury is a globally distributed neurotoxic pollutant that can be biomagnified in marine fish to levels that are harmful for consumption by humans and other animals. The degree to which mercury has infiltrated the oceans yields important information on the biogeochemistry of mercury and its expected effects on fisheries during changing mercury emissions scenarios. Mercury isotope measurement of biota from deep-sea trenches was used to demonstrate that surface-ocean-derived mercury has infiltrated the deepest locations in the oceans. It was found that when fish living in the surface ocean die and their carcasses sink (along with marine particles), they transfer large amounts of mercury to the trench foodwebs leading to high concentrations of mercury in trench biota.
A microbial metabolite synergizes with endogenous serotonin to triggerC. elegansreproductive behavior
Authors: Chen Yen-Chih , Seyedsayamdost Mohammad R. , Ringstad Niels 
Published: November 2020

SignificanceNeurochemical signaling pathways are important therapeutic targets for the treatment of brain disorders, including complex psychiatric disorders that affect poorly understood cognitive and affective mechanisms. Despite a pressing need for improved psychopharmacology, it has proved difficult to discover new types of small molecules that target neurochemical signaling. We have used a behavior-based screen to identify natural products that strongly and specifically interact with serotonin signaling in the nervous system of the nematodeCaenorhabditis elegans. This approach identified a microbial metabolite that is structurally unrelated to known activators of serotonin signaling. Our study suggests that microbe-derived small molecules can be a rich source of novel neuroactive compounds.
Evidence accumulation for value computation in the prefrontal cortex during decision making
Authors: Lin Zhongqiao , Nie Chechang , Zhang Yuanfeng , Chen Yang , Yang Tianming 
Published: November 2020

SignificanceDecision making involves the evaluation of the options, and the current popular theory puts the orbitofrontal cortex (OFC) in a central role in this process. However, by using a sophisticated task design in which the decision making requires both evidence accumulation over time and a stimulus-to-action transformation, we found that the OFC neuronal activity reflected neither. Both processes were instead represented in the dorsolateral prefrontal cortex (DLPFC), and the stimulus-to-action transformation occurred before the evidence accumulation. Our study argued for a more limited role of the OFC in value-based decision making than previously proposed and indicated how the OFC and the DLPFC may work together to compute value during decision making.
Fly-ash Enriched Earthen Un-Burnt Bricks for Low-cost Housing
Authors: Jena Joygopal , Sahoo Chinmayanada , Singh Kalyani S. 
Published: November 2020

Abstract
In spite of various major steps taken by the Governments, housing problem in rural India is becoming bad to worse due to population explosion and their low income. Various low-cost housing schemes has been floated through use of cheaper construction materials. Therefore, development of new cheaper materials has become need of the day. This can be possible by production of new materials produced from various by-products or wastes justifying the slogan converting ‘Wastes into Wealth’. Fly ash, a coal combustion by-product available in power plants is one such material available in plenty in our surroundings those are posing problem to the environment. Presently, these are utilised by mixing various cementitious materials in production of bricks, those are substituting conventional bricks, for their cost effectiveness. But, the extreme poor people of tribal areas are deprived of using these bricks in their houses due to non-availability and financial constraints. Most of tribal houses in KBK districts of Odisha, Eastern and Central rural of Chhattisgarh, some parts of Jharkhand, Bihar and West Bengal are made of walls with twigs plastered with mud and Nauria tiled roofing. To bridge the gap a new product ‘Fly ash Enriched Earthen Unburnt brick’ has been proposed. Necessary laboratory tests for the proposed product has been carried and their suitability is presented in this paper. Poor people who can’t afford for standard bricks for their houses, this can be an alternate cheaper solution for them.
A Review on the Bacterial Concrete Properties
Authors: Jena Shradha , Basa Bidyadhar , Chandra Panda Kishor 
Published: November 2020

Abstract
A very commonly used and widespread building material, concrete has various limits of using it, one of which is crack formation. Formation of larger cracks let water and CO2 enter into the building materials which in turn react along with other chemicals causing an eye catching reduction in strength and durability. If immediate remedies are not taken to heal the cracks, it might lead to more serious problems like bigger cracks, more leakage of water, reduced strength, costlier to repair. Hence the best way to deal with such situation and to heal concrete even before it starts spreading is self-healing concrete. Self-healing concrete is the most recent and most current cutting-edge technological development in the field of building materials. Self-healing bacteria has the capacity to heal itself. The underlying principle of this mechanism is forming calcium carbonate precipitate with the help of bacteria as a blocking material for cracks. This new and innovative introduction of bacteria into the building materials show new light on production of sustainable, durable, strong concrete having prolonged life period. Due to the introduction of bacteria in concrete, the name becomes bacterial concrete. Bacterial / microbial concrete is pollution free, economic and cost effective. This paper aims at defining bacterial concrete, mechanism and its effects on concrete properties.