Multiple Sweeps Research Articles

Electrochemical and Spectroscopic Investigations of Bismuth(III) Pharmaceuticals with L-Glutathione

Due to the importance of L-cysteine in the human system, the interaction of metals with this amino acid are worthy of investigation by various methods. In this laboratory1, we have investigated the interaction of bismuth(III) compounds with L-cysteine by both cyclic voltammetry and UV-VIS spectroscopy in an attempt to understand the role of bismuth in treating gastrointestinal maladies.2 The addition of bismuth(III) compounds to solutions of L-cysteine causes a negative potential shift for bismuth(III) reduction as an indication of complex formation between bismuth(III) and L-cysteine. This interaction is also evident by the appearance of a UV-VIS spectroscopic band at 340 nm (Bi-sulfur bond). Even at low pH values (pH 1.0), electrochemical studies show evidence of some kind of interaction even when there is no 340 nm band. These investigations have been conducted at pH 1.00 and 3.00 to simulate conditions in the human stomach and at pH 7.40 MOPS [(3-N-morpholino)propanesulfonic acid] to simulate general physiological conditions, in particular the intestinal tract. Recent work has involved extension of this work to L-glutathione, a tripeptide incorporating L-cysteine, under similar conditions. As might be expected, these interactions are considerably more complicated than those involving L-cysteine. As an example, there is a considerable positive potential shift for the reduction of bismuth(III) citrate in the presence of L-glutathione on the first and second voltammetric sweeps at gold and glassy carbon electrodes. This behavior evidently reflects the rather long (several seconds) time required for the re-formation of the bismuth complex with L-glutathione after its reductive ligand (L-glutathione) loss during bismuth(III) reduction on the first sweep. In addition, there is evidence of a film buildup on the electrode surface as observed by peak current increases during multiple potential sweeps. These observations are planned for inclusion in this symposium presentation.References T. Cheek and D. Peña, J. Electrochem. Soc., 167, 155522 (2020)Li, R. Wang, and H. Sun, Acc. Chem. Res., 52, 216 (2019).

Fatigue-Healing Performance Analysis of Warm-Mix Rubber Asphalt Mastic Using the Simplified Viscoelastic Continuum Damage Theory

As a green and low-carbon road material, warm-mix rubber asphalt (WMRA) has received extensive attention from scholars for its road performance. In the in-depth study of its properties, the fatigue characteristics of WMRA are particularly critical. However, in current studies on asphalt fatigue performance, its self-healing ability is often underestimated or neglected. Furthermore, the simplified viscoelastic continuum damage theory (S-VECD), with its accuracy, speed, and convenience, provides a powerful tool for analyzing asphalt fatigue performance. Therefore, to analyze the fatigue and self-healing performances of WMRA in practical applications, four sample materials were selected in this study: virgin asphalt mastic (VAM), rubber asphalt mastic (RAM), Sasobit rubber asphalt mastic (SRAM), and Evotherm rubber asphalt mastic (ERAM). Subsequently, the samples were subjected to a comprehensive experimental design with frequency sweep tests, linear amplitude sweep tests, and multiple intermittent loading time sweep tests under different aging conditions. The fatigue and self-healing performances of different aging degrees and different types of WMRA were evaluated based on the S-VECD theory. The results show that aging reduces the fatigue and self-healing performances of asphalt mastic to a certain extent, and at a 7% strain, the fatigue life of SRAM after long-term aging is only 30.7% of the life of the unaged sample. The greater the aging degree, the more pronounced the effect. Under different aging levels, the warm-mix agent can significantly improve the fatigue and self-healing performances of rubber asphalt mastic. After undergoing ten fatigue intermittent loading tests, the recovery rate of the complex shear modulus for the long-term aged VAM was 0.65, which is lower than that of SRAM under the same conditions, and the warm mix can further extend the fatigue life of rubber asphalt by improving the self-healing properties of the asphalt. The role of Sasobit in enhancing the fatigue and self-healing performances of rubber asphalt mastic is more significant. This study can provide a theoretical basis for the promotion and application of WMRA pavements and contribute to the sustainable development of road construction.

Asphalt binder modified with high density polyethylene: 2S2P1D rheological modelling and damage characterization

ABSTRACT The new needs in the paving industry have led to the intensification of the use of modified binders, and the use of plastics (non-biodegradable waste) can be an ally in facing both environmental and technical challenges. This study evaluated the feasibility of modifying a conventional asphalt binder with high density polyethylene (HDPE) at contents of 1, 3 and 5% for performance improvement, using rheological and performance tests. The linear viscoelastic properties were obtained by the temperature-frequency sweep test, and for the first time the 2S2P1D rheological model was used to describe these data for an HDPE-modified binder. Resistance to permanent deformation and fatigue was verified by the Multiple Stress Creep Recovery (MSCR) and Linear Amplitude Sweep (LAS) tests, respectively. The Fatigue Factor of Binder was obtained at 3 levels of strain for the first time for this material. HDPE made the material stiffer and more elastic observed by the coefficients of the 2S2P1D model. The modification resulted in better performance regarding permanent deformation and in general had an impact of less than 10% on the fatigue life of the material. Thus, it is possible to state that HDPE can be incorporated into the asphalt binder without harming its performance.

Recycling the electric arc furnace waste after geopolymerization in bitumen: experimental analyses and LCA study

The conversion of solid waste materials into cleaner products for road paving. applications appears to be a promising and sustainable option. However, there is still a lack of attention given to quantifying the potential environmental benefits of recycling solid wastes in asphalt pavements, regarding the impact on asphalt performance. To address this gap, the present study investigates the effects of recycling electric arc waste based geopolymers on asphalt binder and mixture characteristics, as well as environmental outputs. For this purpose, geopolymers were incorporated into both neat and SBS-modified binders. A comprehensive rheological investigation was conducted using cutting-edge multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS) analyses. Stability, Marshall quotient, and flow values, as well as dry and wetconditioned tensile strength were considered, to determine asphalt mixture properties. In the Life Cycle Assessment (LCA), greenhouse gases resulting from fuel and energy consumption in each inventory phase were determined. The varying service lifetimes, maintenance and rehabilitation plans, and production and construction requirements of the different asphalt schemes were taken into account. Subsequently, the environmental impacts of the asphalt mixtures, including global warming potential, acidification, eutrophication, and smog formation potential, along with the total energy demand, were calculated across different stages of the LCA. The results show that the geopolymerization process results in important contributions in terms of both environmental savings and pavement performance.

Sexually discordant selection is associated with trait-specific morphological changes and a complex genomic response.

Sexes often have differing fitness optima, potentially generating intra-locus sexual conflict, as each sex bears a genetic "load" of alleles beneficial to the other sex. One strategy to evaluate conflict in the genome is to artificially select populations discordantly against established sexual dimorphism (SD), reintroducing attenuated conflict. We investigate a long-term artificial selection experiment reversing sexual size dimorphism in Drosophila melanogaster during ~350 generations of sexually discordant selection. We explore morphological and genomic changes to identify loci under selection between the sexes in discordantly and concordantly size-selected treatments. Despite substantial changes to overall size, concordant selection maintained ancestral SD. However, discordant selection altered size dimorphism in a trait-specific manner. We observe multiple possible soft selective sweeps in the genome, with size-related genes showing signs of selection. Patterns of genomic differentiation between the sexes within lineages identified potential sites maintained by sexual conflict. One discordant selected lineage shows a pattern of elevated genomic differentiation between males and females on chromosome 3L, consistent with the maintenance of sexual conflict. Our results suggest visible signs of conflict and differentially segregating alleles between the sexes due to discordant selection.

Rheological and microstructural properties of nano-composite bitumen modified by nano-alumina and low-SBS content

This study explores a new nanocomposite-modified bitumen (NCMB) that could be more cost-effective and environmentally friendly than current options. It achieves this by combining a lower amount of styrene butadiene styrene (SBS) polymer with nano-alumina, aiming to improve performance at high and moderate temperatures. This innovative material aims to overcome the performance limitations of traditional polymer-modified bitumen (PMB). Moreover, this NCMB, which uses less modifier (SBS) and nano-alumina, paves the way for more economical and eco-friendly roads, leading to significant fuel savings. The new NCMB was prepared by mixing various nano-alumina contents (2, 3, 4, and 5 % by weight of bitumen) with low-SBS content (2.5 % by weight of bitumen) PMB. Multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS) tests, further the Superpave standard method, were used to assess the rutting and fatigue cracking resistance of PMB and NCMBs. Field emission scanning electron microscopy (FESEM) with elemental analysis by energy dispersive X-ray spectroscopy map (EDS) techniques and Fourier-transform infrared spectroscopy (FTIR) was used to investigate the microstructural and elemental characteristics of NCBBs. The results demonstrated that adding nano-alumina to low-SBS content PMB significantly enhanced both the storage stability and its durability over time (i.e. aging resistance) of the NCMBs. The MSCR test results showed that samples with 5 % nano-alumina had a rutting resistance higher than the PMB, up to 31 %. The NCMB samples with 4 % nano-alumina demonstrated a significant improvement in fatigue resistance of up to 67 %. The FTIR results revealed a 64 % improvement in aging resistance for NCMBs containing 3 % nano-alumina compared to the PMB. The storage stability values increased for all NCMB types and reached 62 % for the samples with 5 % nano-alumina. Overall, adding nano-alumina to low-SBS content PMB led to a remarkable improvement of rheological properties at intermediate and high temperatures and a stable system under storage conditions with high anti-aging resistance.

Effects of non-linearity and thixotropy in linear amplitude sweep testing for the evaluation of self-healing of bituminous binders

Linear amplitude sweep tests have been demonstrated to have good potential in being used for the evaluation of self-healing properties of neat and polymer-modified bituminous binders. Past research works, however, have neglected the effects of material non-linearity and thixotropy. This implies that the whole material integrity loss is attributed to damage and all restoration to self-healing, thus resulting in the possible overestimate of both damage and self-healing when evaluating the fatigue performance of materials. In the study described in this paper, specific experimental and analytical methods were adopted with the purpose of separating non-linearity and thixotropy in LAS healing tests. Non-linearity was assessed by means of multiple strain sweep tests carried out to determine the material non-linear viscoelastic moduli at specific testing temperatures. Thixotropy was considered by coupling self-healing LAS testing with a purposely defined test in which loading was applied to the undamaged material after a rest period equal to that applied in self-healing tests. Obtained results were processed by means of an analytical approach based on the simplified viscoelastic continuum damage model. Quantification of self-healing included the determination of material integrity and damage parameters recovered after the rest period. Such parameters, calculated by excluding time-dependent and non-linear biasing effects, can be used as straightforward indicators of the self-healing potential of neat and polymer-modified bituminous binders. Moreover, obtained results substantiate the concept that time–temperature superposition is still applicable when non-linearity is incorporated into the simplified viscoelastic continuum damage model.

An evaluation proposal for the fatigue and healing performances of high-viscosity polymer-modified bitumen based on continuous multiple linear amplitude sweep

Due to the excellent shear deformation resistance of high-viscosity polymer-modified bitumen (HVPMB), the traditional methods based on time sweep and linear amplitude sweep (LAS) had problems with insufficient damage accumulation and inability to disrupt the integrity of HVPMB, making it difficult to accurately evaluate its fatigue and healing characteristics. To solve this problem, this study developed an effective evaluation proposal called continuous multiple LAS (MLAS) test and MLAS-based healing (MLASH) test. One base bitumen and three HVPMBs were selected for related experiments. MLAS test results confirmed that the percentage of strain energy attenuation (PSEA) can be used to evaluate the fatigue damage degree of HVPMBs. The lower the PSEA, the lesser damage. Combined with the fluorescence microscope and direct photography observation, the fatigue hairline cracks during MLAS test gradually expanded from the sample periphery to center until completely destroyed. Further, the MLASH test was developed to evaluate the healing performance of HVPMB by introducing intermittent duration into MLAS test. The variation of PSEA after tenth LAS loading (i.e. ΔPSEA) was proposed to evaluate the healing performance of HVPMB. The larger the ΔPSEA, the better the healing performance of HVPMB. All HVPMBs showed satisfactory healing performance once there was sufficient healing intermittent time (e.g. 180 s), and the healing performance was negatively correlated with the damage degree. Notably, the polymer structures had a dual effect on the healing performance of HVPMB, that is, they promoted the elastic healing recovery of HVPMB at lower temperature, while hindering the flow healing recovery at higher temperatures. Moreover, different temperatures caused a shift in the ranking of healing performance of various HVPMBs, thus the healing result at only single temperature cannot comprehensively represent the healing performance of HVPMB. Overall, the newly developed evaluation proposal can help to select HVPMB with excellent fatigue resistance and healing properties and provide a certain basis for accurately predicting HVPMB pavement life.

Multi-phase quantitative compositional mapping by LA-ICP-MS: Analytical approach and data reduction protocol implemented in XMapTools

Mapping of trace element signatures is an expanding tool in geoscience and material sciences, which allows the study of solid materials, and processes that may not be captured by major elements. Developments in laser-ablation inductively-coupled-plasma mass-spectrometry (LA-ICP-MS) capabilities in the last decade now provide the necessary spatial resolution for in situ element mapping. The acquisition of two-dimensional, fully quantitative and geologically meaningful data with LA-ICP-MS is still a challenging task, and a particular obstacle is the calibration of inhomogeneous phases, such as chemically zoned minerals. This work presents a novel approach to data reduction and image generation for multi-element mapping employing LA-ICP- quadrupole MS (LA-ICP-QMS), implemented in the free and open-source software XMapTools. Three geological applications are presented to illustrate the benefits of the procedures. Garnet from an eclogitic sample (Lato Hills, Togo) and plagioclase, K-feldspar, biotite from a migmatite sample (El Oro Complex, Ecuador) were mapped multiple times at different spatial resolutions to test the calibration quality and chemical detection capabilities. Rutile in a metapelite sample (Val Malenco, Italian Alps) was mapped, and Zr-in-rutile thermometry shows a temperature range of 510 to 550 °C within a single grain. The accuracy of the LA-ICP-MS method was verified by comparison with zoned major and minor element maps (garnet, plagioclase) and Ti-in-biotite geothermometry maps obtained by electron probe microanalysis (EPMA). A spatial resolution of up to 5 μm is achieved with LA-ICP-QMS, which is similar to the resolution reported for LA-ICP time-of-flight mass spectrometry (LA-ICP-TOFMS), albeit at significantly lower acquisition speed. Maps with lower spatial resolution offer better chemical detection power as demonstrated by lower per-pixel limit of detection (LOD) map calculation. Moreover, such maps are also recorded faster. The pixel allocation strategy and the instrumental conditions also have a direct impact on map quality. We recommend that maps are interpolated to square pixels, where a pixel consists of multiple sweeps to gain an improved detection power. Benchmarks using an emulated LA-ICP-MS mapping show that the spot size, together with scan direction, can lead to a shift in composition depending on the feature size of chemical patterns. This is verified by mapping a thin 10 μm annulus in garnet visible in REE and such compositional shifts can have a significant impact on e.g., diffusion modelling. The new software solution provides a multi-standard and variable composition calibration of LA-ICP-MS maps with single pixel LOD filtering at 95% confidence, allowing the user to quantify inhomogeneous materials of major and trace elements simultaneously with improved accuracy.

A wideband low frequency 3D printed electromagnetic energy harvester based on orthoplanar springs

Electromagnetic energy harvesters are commonly known for their high performances in terms of power output conversion, and they are suitable for low frequency environmental vibrations.This work reports the study, design, development and experimental validation of a new extremely compact, low frequency, electromagnetic energy harvester based on two stacked ortho-planar springs, which exploits a promising magnets disposition.The device is composed by two stacked ortho-planar springs connected externally by a rigid frame. The two internal moving parts are connected to each other by a central pivot where an array of magnets is fixed on in a peculiar disposition: a half has a magnetic field directed upward, while the other half directed downward. A copper coil is wound into a housing fixed on the external frame. It comes a central massive cursor that axially moves, exploiting the springs compliance, relatively to the external frame.The prototype was almost completely realized by using Filament Fused Fabrication (FFF) additive manufacturing process in Onyx material, carbon fibre reinforced nylon.In the experimental assessment an oscillating excitation was applied on the external frame in multiple linear sweep frequency tests with different amplitude signals. The experimental validation shows a large bandwidth, from 10 to 30 Hz, and consistent output voltage and power signals.

Simulation of the Time Needed for Long-Term Asphalt Ageing in the Rolling Thin Film Oven Relative to That of the Pressure Ageing Vessel.

Rheological test standards require asphalt samples, both original and under ageing conditions. The most common laboratory equipment in specifications for short-term and long-term ageing simulation tests are the rolling thin film oven (RTFO) and the pressure ageing vessel (PAV). However, the cost of acquiring PAV and the duration of long-term ageing tests can be a limiting factor. This work aimed to establish the equivalent time of the long-term ageing test in the RTFO that corresponds to the PAV. For this, the Brazilian asphalt PEN 50/70, specified by penetration, was aged at different times (85, 170, 255, and 340 min) in the RTFO at the standard temperature (163 °C). For each time, using a dynamic shear rheometer (DSR), tests such as Multiple Stress Creep Recovery (MSCR) and Linear Amplitude Sweep (LAS) were performed, and the rheological properties (complex modulus (G*) and phase angle (δ)) were measured. The same tests were conducted on the samples aged in the long term and in the PAV. The test parameters obtained from applying different times while using the RTFO were compared with the PAV results, and the equivalent time was settled through linear regression, resulting in 300 min. In order to confirm the equivalent time, samples aged in the RTFO for 300 min were assessed using the same rheological tests, and the parameters were compared to those obtained after PAV ageing. At the equivalent time, the difference between RTFO and the PAV for the rutting parameter (G*/sinδ, 58 °C) was 6%, while for the fatigue parameter (G*.sinδ, 19 °C), the difference was 1.0%. The MSCR non-recoverable creep compliance parameter differences, considering stress levels of 0.1 kPa and 3.2 kPa, were 9.7% and 11.7%, respectively. For the fatigue life obtained in the LAS test at strain levels of 1.25% and 2.5%, the difference between RTFO and PAV, at the equivalent time, was 7.6% and 7.8%, respectively. For the Brazilian unmodified asphalt PEN 50/70 and parameters evaluated in this work, 300 min is the equivalent time that simulates long-term ageing in the RTFO.

Exploring Partial Structural Disorder in Anhydrous Paraxanthine through Combined Experiment, Solid-State Computational Modelling, and Molecular Docking

Paraxanthine (PX), a major metabolite of caffeine, a protective agent against Alzheimer’s and Parkinson’s disease, and a promising drug for the treatment of post-COVID 2019 anosmia and ageusia, has been studied in the solid state and protein–ligand complex. Partial disorder in PX, caused by the methyl group at the N(7) position, has been modelled and discussed. The relationship between the unusual structural disorder and the propensity to form a specific system of non-covalent bonds was analyzed. Three 1H-14N NMR-NQR (nuclear magnetic resonance–nuclear quadrupole resonance) experimental techniques were used, namely multiple frequency sweeps, Larmor frequency scanning, and the two-frequency irradiation, followed by solid-state computational modelling (density functional theory, supplemented by quantum theory of atoms in molecules, 3D Hirshfeld surfaces, and reduced density gradient), and molecular docking approaches. New quantitative methods for estimating changes in the global pattern of interactions under the influence of rotation of the methyl group in N(7) based on the Pompeiu–Hausdorff and Bhattacharayya metrics and the Wasserstein distance have been proposed and applied. A spectrum consisting of 12 lines, indicating the presence of 4 chemically inequivalent nitrogen sites in the PX molecule, was recorded, and the lines’ assignment to particular sites was made. The influence of the methyl rotation on the eigenvalues and eigenvectors of the electric field gradient tensor, NQR parameters, and resonance line positions was modelled in the solid (GGA/RPBE, m-GGA/RSCAN) and cluster (Minnesota M062X hybrid). Three factors have been found to determine structural disorder in PX: larger crystal voids near the methyl at N(7) than at N(1) (opening the path for the disorder), hyperconjugation strongly affecting the density distribution in the five-membered ring, and the involvement of the methyl group at N(7) in many non-covalent bonds that intercept (capture) subsequent jumping protons. The Pompeiu–Hausdorff and Bhattacharayya metrics and the Wasserstein distance confirmed the changes in the distribution and strength of non-covalent interactions throughout the molecule as a result of methyl rotation. This effect is clearly visible regardless of the type of metric, and its order of magnitude is consistent with the modulation effect of the NQR spectra (experimental and calculated). Through molecular docking, it was discovered that the PX moiety in protein–ligand complexes adopt the same methyl group conformation at N(7) as in the solid state. It was found that the cooperation–competition between the C-H⋯O hydrogen bonds and C-H⋯H-C dispersion interactions is the crucial factor that impedes methyl rotation and induces structural disorder, as well as being an important factor in the formation of the protein–ligand complexes.

Dynamic Analysis and Experiment of Multiple Variable Sweep Wings on a Tandem-Wing MAV

The current morphing technologies are mostly regarded as auxiliary tools, providing additional control torques to enhance the flight maneuverability of unmanned aerial vehicles (UAVs), and they cannot exist independently of the traditional control surfaces. In this paper, we propose a tandem-wing micro aerial vehicle (MAV) with multiple variable-sweep wings, which can reduce the additional inertia forces and moments and weaken the dynamic coupling between longitudinal and lateral motion while the MAV morphs symmetrically for pitch control or asymmetrically for roll control, thereby flying without the traditional aileron and elevator. First, load experiments were conducted on the MAV to verify the structural strength of the multiple variable sweep wings, and the control moments caused by the morphing of the MAV were presented through numerical simulations. Then, the effects caused by symmetric and asymmetric morphing were investigated via dynamic response simulations based on the Kane dynamic model of the MAV, and the generated additional inertia forces and moments were also analyzed during morphing. Finally, dynamic response experiments and open-loop flight experiments were conducted. The experimental results demonstrated that the morphing mode in this study could weaken the coupling between the longitudinal and lateral dynamics and that it was feasible for attitude control without the traditional aileron and elevator while flying.

Laboratory investigation of the impact of peanut husk ash as an asphalt binder modifier on physical and rheological properties

Researchers propose using agricultural waste into asphalt pavements as a means to raise recycling rate of waste, conserve natural resources, and reduce disposal issues. This paper was set out to explore the ability of peanut husk ash (PHA) as an asphalt binder modifier. To this end, scanning electron microscope (SEM), softening point, penetration, ductility, storage stability, rotational viscosity, multiple stress creep recovery (MSCR), temperature sweep, frequency sweep, and bending beam rheometer (BBR) tests were applied. Besides, the temperature susceptibility was evaluated using the penetration index, while the fatigue parameter was applied to assess the intermediate temperature performance of asphalt binder. Moreover, the response surface methodology (RSM) was performed to assess the interactive impact of load frequency, temperature, and PHA concentrations on the rutting factor and complex modulus, besides the interaction between them. Moreover, models were proposed to fit the findings of experimental work to predict the responses. The findings manifested that asphalt binder can be modified with 8% or less of PHA without experiencing phase separation issues during high temperature storage. Furthermore, the SEM demonstrated that PHA was well dispersed in the modified asphalt. Moreover, the increment of PHA led to increase penetration index, softening point, viscosity, rutting parameter, percent recovery, and complex shear modulus, as well as reducing nonrecoverable creep compliance (Jnr), phase angle, penetration, and ductility. Although the high temperature performance was enhanced, there was a decrease in fatigue and low temperature cracking resistance. The RSM analysis revealed that the input factors significantly affected the asphalt's rutting factor, and complex modulus, and quadratic models were suggested to predict the potential for rutting.

Elucidating the Role of Noncovalent Interactions in Favipiravir, a Drug Active against Various Human RNA Viruses; a 1H-14N NQDR/Periodic DFT/QTAIM/RDS/3D Hirshfeld Surfaces Combined Study.

Favipiravir (6-fluoro-3-hydroxypyrazine-2-carboxamide, FPV), an active pharmaceutical component of the drug discovered and registered in March 2014 in Japan under the name Avigan, with an indication for pandemic influenza, has been studied. The study of this compound was prompted by the idea that effective processes of recognition and binding of FPV to the nucleic acid are affected predominantly by the propensity to form intra- and intermolecular interactions. Three nuclear quadrupole resonance experimental techniques, namely 1H-14N cross-relaxation, multiple frequency sweeps, and two-frequency irradiation, followed by solid-state computational modelling (density functional theory supplemented by the quantum theory of atoms in molecules, 3D Hirshfeld Surfaces, and reduced density gradient) approaches were applied. The complete NQR spectrum consisting of nine lines indicating the presence of three chemically inequivalent nitrogen sites in the FPV molecule was detected, and the assignment of lines to particular sites was performed. The description of the nearest vicinity of all three nitrogen atoms was used to characterize the nature of the intermolecular interactions from the perspective of the local single atoms and to draw some conclusions on the nature of the interactions required for effective recognition and binding. The propensity to form the electrostatic N-H···O, N-H···N, and C-H···O intermolecular hydrogen bonds competitive with two intramolecular hydrogen bonds, strong O-H···O and very weak N-H···N, closing the 5-member ring and stiffening the structure, as well as π···π and F···F dispersive interactions, were analysed in detail. The hypothesis regarding the similarity of the interaction pattern in the solid and the RNA template was verified. It was discovered that the -NH2 group in the crystal participates in intermolecular hydrogen bonds N-H···N and N-H···O, in the precatalytic state only in N-H···O, while in the active state in N-H···N and N-H···O hydrogen bonds, which is of importance to link FVP to the RNA template. Our study elucidates the binding modes of FVP (in crystal, precatalytic, and active forms) in detail and should guide the design of more potent analogues targeting SARS-CoV-2. Strong direct binding of FVP-RTP to both the active site and cofactor discovered by us suggests a possible alternative, allosteric mechanism of FVP action, which may explain the scattering of the results of clinical trials or the synergistic effect observed in combined treatment against SARS-CoV-2.

Nonmonotonic Variation of Rutting Resistance and Fatigue Life for Polyethylene Modified Bitumen with Different Carbon Black Loading

Polyethylene (PE) and carbon black (CB) were premixed in this study for bitumen modification. The service performance of PE/CB-modified bitumen (PMB) was mainly explored by multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS) tests to reveal the rutting resistance and fatigue life, respectively. Low-temperature properties were evaluated by glass transition temperature (Tg) measured by dynamic mechanical analysis (DMA). X-ray diffraction (XRD) results suggested that the crystalline structure of PE was almost the same regardless of different CB loading additions. It was found that the both rutting resistance and fatigue life of PMBs showed nonmonotonic variation with CB loading. The mechanism for this variation was closely related to the microstructure induced by phase separation, CB nanoparticle aggregation and PE crystallinity. As revealed by optical and atomic force microscopy, two different phase structures, network and droplet-matrix structure, can be formed in PMBs when the CB loading changes. In particular, a double percolated network structure can be formed, consisting of a PE-rich network in the bitumen-matrix and CB nanoparticle network within a PE-rich phase. With the presence of this structure, the rutting resistance and fatigue life of PMB can be significantly improved.

Strong Positive Selection in Aedes aegypti and the Rapid Evolution of Insecticide Resistance.

Aedes aegypti vectors the pathogens that cause dengue, yellow fever, Zika virus, and chikungunya and is a serious threat to public health in tropical regions. Decades of work has illuminated many aspects of Ae. aegypti's biology and global population structure and has identified insecticide resistance genes; however, the size and repetitive nature of the Ae. aegypti genome have limited our ability to detect positive selection in this mosquito. Combining new whole genome sequences from Colombia with publicly available data from Africa and the Americas, we identify multiple strong candidate selective sweeps in Ae. aegypti, many of which overlap genes linked to or implicated in insecticide resistance. We examine the voltage-gated sodium channel gene in three American cohorts and find evidence for successive selective sweeps in Colombia. The most recent sweep encompasses an intermediate-frequency haplotype containing four candidate insecticide resistance mutations that are in near-perfect linkage disequilibrium with one another in the Colombian sample. We hypothesize that this haplotype may continue to rapidly increase in frequency and perhaps spread geographically in the coming years. These results extend our knowledge of how insecticide resistance has evolved in this species and add to a growing body of evidence suggesting that Ae. aegypti has an extensive genomic capacity to rapidly adapt to insecticide-based vector control.

Multi-sweep 3-dimensional ultrasound is accurate for in vivo muscle volume quantification, expanding use to larger muscles

Muscle volume is an important parameter in analyzing three-dimensional structure of muscle–tendon units. Three-dimensional ultrasound (3DUS) enables excellent quantification of muscle volume in small muscles; however, when a muscle’s cross sectional area is larger than the field of view of the ultrasound transducer at any point along its length, more than one sweep is necessary to reconstruct muscle anatomy. Confounding image registration errors have been reported between multiple sweeps. Here, we detail imaging phantom studies used to (1) define an acquisition protocol that reduces misalignment in 3D reconstruction caused by muscle deformation, and (2) quantify accuracy of 3DUS for measures of volume when phantoms are too large to be fully imaged via a single transducer sweep. Finally, we (3) establish the feasibility of our protocol for in vivo measures by comparing biceps brachii muscle volumes using 3DUS and magnetic resonance imaging (MRI). Phantom studies indicate operator intent to use constant pressure across multiple sweeps effectively mitigates image misalignment, yielding minimal volume error (1.70 ± 1.30%). Intentional application of different pressure between sweeps replicated discontinuity observed previously, leading to larger errors (5.30 ± 0.94%). Based on these findings, we adopted a gel bag standoff and acquired in vivo images of biceps brachii muscles using 3DUS and compared this volume to MRI. We did not observe misalignment errors and there were no significant differences between imaging modalities (-0.71 ± 5.03 %), indicating 3DUS can reliably be used to quantify muscle volume in larger muscles requiring multiple transducer sweeps.

Reliability of 3D freehand ultrasound to assess lower limb muscles in children with spastic cerebral palsy and typical development.

This study investigated the reliability of 3-dimensional freehand ultrasound (3DfUS) to quantify the size (muscle volume [MV] and anatomical cross-sectional area [aCSA]), length (muscle length [ML], tendon length [TL], and muscle tendon unit length [MTUL]), and echo-intensity (EI, whole muscle and 50% aCSA), of lower limb muscles in children with spastic cerebral palsy (SCP) and typical development (TD). In total, 13 children with SCP (median age 14.3 (7.3) years) and 13 TD children (median age 11.1 (1.7) years) participated. 3DfUS scans of rectus femoris, semitendinosus, medial gastrocnemius, and tibialis anterior were performed by two raters in two sessions. The intra- and inter-rater and intra- and inter-session reliability were defined with relative and absolute reliability measures, that is, intra-class correlation coefficients (ICCs) and absolute and relative standard error of measurement (SEM and SEM%), respectively. Over all conditions, ICCs for muscle size measures ranged from 0.818 to 0.999 with SEM%s of 12.6%-1.6%. For EI measures, ICCs varied from 0.233 to 0.967 with SEM%s of 15.6%-1.7%. Length measure ICCs ranged from 0.642 to 0.999 with SEM%s of 16.0%-0.5%. In general, reliability did not differ between the TD and SCP cohort but the influence of different muscles, raters, and sessions was not constant for all 3DfUS parameters. Muscle length and muscle tendon unit length were the most reliable length parameters in all conditions. MV and aCSA showed comparable SEM%s over all muscles, where tibialis anterior MV was most reliable. EI had low-relative reliability, but absolute reliability was better, with better reliability for the distal muscles in comparison to the proximal muscles. Combining these results with earlier studies describing muscle morphology assessed in children with SCP, 3DfUS seems sufficiently reliable to determine differences between cohorts and functional levels. The applicability on an individual level, for longitudinal follow-up and after interventions is dependent on the investigated muscle and parameter. Moreover, the semitendinosus, the acquisition, and processing of multiple sweeps, and the definition of EI and TL require further investigation. In general, it is recommended, especially for longitudinal follow-up studies, to keep the rater the same, while standardizing acquisition settings and positioning of the subject.

Effectiveness of multiple versus once-only membrane sweeping at term in preventing prolonged pregnancy: A randomised controlled trial

BackgroundBetween 4 and 18% of pregnancies are prolonged. Prolonged pregnancy is associated with adverse maternal and perinatal outcomes. ObjectivesTo compare the effectiveness of once-only versus multiple (weekly) membrane sweeping in reducing the incidence of prolonged pregnancy. Materials and methods: This randomised controlled trial was conducted over a two-year period, from January 2018 to December 2019, at the Federal Medical Centre and Diete-Koki Memorial Hospital, both in Yenagoa, Bayelsa State, Nigeria. Seven hundred and eighty-six women were equally randomized into two groups: once-only and multiple membrane sweeping, initiated at 39 weeks’ gestational age, but 742 women were included in the analysis. Data obtained was analysed using the Statistical Package for Service Solutions for Windows® version 20, SPSS Inc.; Chicago, USA). Associations between categorical independent and outcome variables were assessed, where applicable, using Chi square test at 95% confidence interval. A P-value of <0.05 was considered statistically significant. ResultsThere were no statistically significant differences between the two groups in terms of time interval between membrane sweeping and delivery (P = 0.85), spontaneous onset of labour (P = 0.21), induction of labour (P = 0.21) and Caesarean section rate (P = 0.68). The maternal complications of vaginal bleeding and pre-labour rupture of membranes following membrane sweeping in the two groups were also comparable (P = 0.45 each). All the women were satisfied and membrane sweeping was acceptable to all of them. ConclusionOnce-only membrane sweeping at 39 weeks’ gestational age is as effective as multiple membrane sweeping for the prevention of prolonged pregnancy. Multiple membrane sweeping does not confer any added advantage/benefit over a single sweep.