Macroscopic Effects Research Articles

SARS-CoV-2 and the Host Cell: A Tale of Interactions

The ability of a virus to spread between individuals, its replication capacity and the clinical course of the infection are macroscopic consequences of a multifaceted molecular interaction of viral components with the host cell. The heavy impact of COVID-19 on the world population, economics and sanitary systems calls for therapeutic and prophylactic solutions that require a deep characterization of the interactions occurring between virus and host cells. Unveiling how SARS-CoV-2 engages with host factors throughout its life cycle is therefore fundamental to understand the pathogenic mechanisms underlying the viral infection and to design antiviral therapies and prophylactic strategies. Two years into the SARS-CoV-2 pandemic, this review provides an overview of the interplay between SARS-CoV-2 and the host cell, with focus on the machinery and compartments pivotal for virus replication and the antiviral cellular response. Starting with the interaction with the cell surface, following the virus replicative cycle through the characterization of the entry pathways, the survival and replication in the cytoplasm, to the mechanisms of egress from the infected cell, this review unravels the complex network of interactions between SARS-CoV-2 and the host cell, highlighting the knowledge that has the potential to set the basis for the development of innovative antiviral strategies.

Interaction behaviors of Cr(VI) at biotite-water interface in the presence of HA: Batch, XRD and XPS investigations

The interaction behaviors of heavy metals and micaceous minerals are extremely important to understand the environmental behaviors of heavy metals. In this work, the interaction behaviors of Cr(VI) and biotite in the presence and absence of HA were studied combining batch and spectroscopic approaches. Batch experiments showed that biotite had the ability to remove Cr(VI) from the water and the removal markedly increased with decreasing pH. However, sorption of total Cr onto biotite increased with increasing pH (2.0–4.0), whilst quickly decreased above pH ∼ 4.0. It was worth noting that redox process of Cr(VI) to Cr(III), caused by structural Fe(II) on biotite, was another important factor for the high removal of Cr(VI) in a pH range of 2.0–4.0. Ionic strength also influenced Cr(VI) removal that Cr(VI) removal became higher with increasing ion strength. The presence of HA did not show obvious macroscopic effect on Cr(VI) removal, however, HA could cover biotite surface, and promote the sorption of total Cr onto biotite and attenuate the reduction effect caused by Fe(II) on biotite. Spectroscopic approaches, like FT-IR, XRD and XPS further confirmed the existence of Cr(III) on biotite interacting with Cr(VI) and the reduction of Cr(VI) to Cr(III) was drove by the Fe(II) dissolving from biotite to Fe(III). Further, sorption effect and reduction effect competitively contributed to the Cr(VI) removal by biotite, and reduction effect played a more important role at lower pH.

Study on preparation of modified antifreezing micro-surfacing and its road performance and antifreezing effect

In order to solve the problem of road freezing caused by low temperature rain and snow in spring and winter, a kind of micro-surfacing with antifreezing function was prepared in this paper. At the same time, styrene-butadiene rubber (SBR) and waterborne epoxy resin (WER) were used to modify the antifreezing micro-surfacing in order to obtain antifreezing micro-surfacing with better performance. The skid resistance, abrasion resistance and rutting resistance of ordinary antifreezing micro-surfacing (OMS) and modified antifreezing micro-surfacing (MMS) with different content of antifreeze fillers were evaluated by sand patch method, British Pendulum Number (BPN), freeze–thaw cycle wet track abrasion test and rutting deformation test. The antifreezing effects of OMS and MMS were compared by icing test and salt precipitation test under the same amount of antifreeze filler. The road performance test results show that the road performance of antifreezing micro-surfacing decreases with the increase of antifreeze fillers. The skid resistance of MMS under different abrasion degrees, abrasion resistance under extreme freeze–thaw environment and rutting resistance are better compared with OMS. The abrasion resistance and rutting resistance performance have been greatly improved, which effectively reduces the risk of large area aggregate stripping of antifreezing micro-surfacing in its special working and service environment. At the same time, the test results of antifreezing effect show that there is no significant difference in macroscopic antifreezing effect between OMS and MMS. The salt precipitation test indicates that the MMS is beneficial to the sustained release of the effective components of antifreezing. Therefore the MMS can effectively alleviate the deterioration of road performance caused by the addition of antifreeze filler. It is helpful to prolong the service life of antifreezing micro-surfacing and gives full play to the advantages of easy paving and efficient antifreezing. The research on the MMS is of great significance to solve the problem of snow freezing in new and old asphalt pavement.

Strategies to activate inert nitrogen molecules for efficient ammonia electrosynthesis: current status, challenges, and perspectives

This review emphasizes the strategies to activate N2 molecules in view of microscopic electron effects, macroscopic external field effects, local microenvironment regulation, and characterization techniques.

Research Progress on Polymeric Inorganic Nanocomposites Insulating Materials

With the rapid development of power energy, electronic information, rail transit, and aerospace industries, nanocomposite dielectric materials have been widely used as new materials. Polymer/inorganic nanocomposite dielectric materials possess excellent physical and mechanical properties. In addition, numerous unique properties such as electricity, thermal, sound, light, and magnetic properties are exhibited by these materials. First, the macroscopic quantum tunneling effect, small‐size effect, surface effect, and quantum‐size effect of nanoparticles are introduced. There are a few anomalous changes in the physical and chemical properties of the matrix, which are caused by these effects. Second, the interaction mechanism between the nanoparticles and polymer matrix is introduced. These include infiltration adsorption theory, chemical bonding, diffusion theory, electrostatic theory, mechanical connection theory, deformation layer theory, and physical adsorption theory. The mechanism of action of the interface on the dielectric properties of the composites is summarized. These are the interface trap effect, interface barrier effect, and homogenization field strength effect. In addition, different interfacial structure models were used to analyze the specific properties of nanocomposite dielectric materials. Finally, the research status of the dielectric properties of nanocomposite dielectric materials is introduced.

Vortex chains in rotating two-dimensional Bose-Einstein condensate in a harmonic plus optical lattices potential

<sec>Bose-Einstein condensate (BEC) is essentially a macroscopic quantum effect with quantum volatility, macroscopic quantum coherence and artificial controllability. Owing to its unique controllability, it becomes a new ideal platform for quantum simulations and studies of interacting quantum systems.</sec><sec>In this paper, the generation of vortices and the formation of vortex chains, as well as characteristics of vortex chains in rotating two-dimensional BEC in a potential composed of harmonic potential and optical lattice are studied numerically. Firstly, the generation of vortices, the formation and distribution of vortex chains and the effects of different physical parameters on the vortex chains in two-dimensional BEC are investigated by using the multigrid preconditioned conjugate gradient method. Secondly, the evolution of the vortex chains with time is studied by using the time-splitting spectral method. The results show that the generation of vortices in BEC trapped in the compound potential corresponds to the minimum value of the potential. When the depth of the optical lattice increases to a certain value, vortex chains are formed in the BEC. With the further increase of the depth of the optical lattice, the vortex depth in the vortex chain in the BEC decreases continuously, and finally the vortex chain disappears completely. When the interaction strength between atoms increases, the distribution range of the condensate expands, and the number of vortices and the number of vortex chains in the condensate also increase. When the interaction strength between atoms increases to a certain value, the symmetry of the vortex chains is broken. As the rotation frequency of the condensate increases, the distribution range of the condensate expands, and the number of vortices and the number of vortex chains in the condensate also increase. When the rotation frequency is close to the external trapping potential frequency, the linear alignment of the vortex chains is disrupted. It is also found that there are three stages in the evolution of the vortex chains in the BEC: in the first stage, vortex chains rotate together with the condensate, and the original chain distribution keeps unchanged; in the second stage, the phenomenon of vortex space extrusion appears, and the vortex chain is destroyed; in the third stage, the phenomenon of vortex space expansion occurs, and finally the vortex chains disappear. The results above show that the depth of the optical lattice, the interaction strength between atoms, and the rotation frequency of the condensate have important effects on the vortices and vortex chains in the condensate. By adjusting these physical quantities, the number of vortices and the shape of vortex chains in the BEC can be effectively manipulated. This may provide some theoretical reference and guidance for future experiments and applications.</sec>

Physical mechanism of London moment

The superconductor will generate a magnetic field inside the superconductor during its rotation, which is called the London moment. At present, a variety of theories including London theory and G-L theory have explained the generation mechanism of London moment. Most of these theories essentially believe that the superconducting electrons in the surface layer of the rotating superconductor lag behind and have a net residual current. The London moment is produced by the net residual current on the surface of the rotating superconductor. However, there is still no clear theoretical explanation for the motion lag of the outermost superconducting electrons in rotating superconductors. In this paper the charged particles in the rotating system and the Berry phase of the superconductor in the rotating superconductor are analyzed. The results show that the Berry curvature of the superconductor has the same expression form as the London moment, indicating that the London moment may be the inverse effect of A-B effect, which is a macroscopic quantum effect based on Berry phase.

Generation of isolated attosecond pulses from atoms driven by optimized two near-infrared pulses and their second harmonic fields

With the rapid development of laser technology, it is possible to control optical waveforms by coherent superposition of electric fields with multiple color components, which creates conditions for generating the ultra-short isolated attosecond pulses (IAP). Based on the strong-field approximation theory, this work focuses on the IAP generated by the optimized multicolor field synthesized by two fundamental near-infrared lasers and their second harmonic fields. The results show that by applying frequency-doubled pulses to the near-infrared laser fields and optimizing the laser parameters, the emission properties of high order harmonics from single atom can be greatly improved, and the nearly attochirp-free harmonic emission can be realized within a certain energy range. As a result, shorter IAPs are obtained. With the consideration of the macroscopic propagation effect of gas, the IAP with a pulse width up to 40 as is generated under appropriate experimental conditions. Finally, the effects of gas pressure on the properties of the high-order harmonic and attosecond pulses are also investigated. This study provides useful theoretical guidance for generating ultra-short IAPs with near-infrared laser pulses in experiment.

Self-cleaning stainless steel surfaces induced by laser processing and chemical engineering

Nanostructured surfaces show a variety of beneficial macroscopic effects. The combination of hierarchic nanostructures with a suitable chemical surface composition allows for the fabrication of surfaces with interesting fluidic properties beyond such effects. This approach enables the specification of nano/microstructure and chemical composition independent of each other. Various hierarchical micro- and nanostructures can be realized by laser texturing of stainless steel surfaces with infrared picosecond laser. Simultaneously, the surface is activated for chemical processing. The surface can now be tuned by bonding of a self-assembled monolayer on the laser-treated surface by chemical treatment. This two-step functionalization process allows the for separated adjusting of the surface topography and chemical composition and thus for the well-defined setting of the surface properties. The fabrication of superhydrophobic surfaces with self-cleaning properties are performed that can be functionalized further by subsequent laser-irradiation. Furthermore, the long-time stability of the surface functionalization in relation to the impact chemicals or radiation was investigated.

Influenza A virus hemagglutinin prevents extensive membrane damage upon dehydration

While the molecular mechanisms of virus infectivity are rather well known, the detailed consequences of environmental factors on virus biophysical properties are poorly understood. Seasonal influenza outbreaks are usually connected to the low winter temperature, but also to the low relative air humidity. Indeed, transmission rates increase in cold regions during winter. While low temperature must slow degradation processes, the role of low humidity is not clear. We studied the effect of relative humidity on a model of Influenza A H1N1 virus envelope, a supported lipid bilayer containing the surface glycoprotein hemagglutinin (HA), which is present in the viral envelope in very high density. For complete cycles of hydration, dehydration and rehydration, we evaluate the membrane properties in terms of structure and dynamics, which we assess by combining confocal fluorescence microscopy, raster image correlation spectroscopy, line-scan fluorescence correlation spectroscopy and atomic force microscopy. Our findings indicate that the presence of HA prevents macroscopic membrane damage after dehydration. Without HA, fast membrane disruption is followed by irreversible loss of lipid and protein mobility. Although our model is principally limited by the membrane composition, the macroscopic effects of HA under dehydration stress reveal new insights on the stability of the virus at low relative humidity.

Controlling Photon Transverse Orbital Angular Momentum in High Harmonic Generation

High harmonic generation (HHG) with longitudinal optical orbital angular momentum has attracted much attention over the past decade. Here, we present the first study on the HHG with transverse orbital angular momentum driven by the spatiotemporal optical vortex (STOV) pulses. We show that the produced spatial-resolved harmonic spectra reveal unique structures, such as the spatially spectral tilt and the fine interference patterns. We show these spatiospectral structures originate from both the macroscopic and microscopic effect of spatiotemporal optical singularity in HHG. Employing two-color counterspin and countervorticity STOV pulses, we further discuss a robust method to control the spatiotemporal topological charge and spectral structure of high-order harmonics. The conservation rule of photon transverse orbital angular momentum in HHG process is also discussed when mixing with photon spin angular momenta.

Mineralogical Transformations in Granitoids during Heating at Fire-Related Temperatures

Fire is a major decay agent of rocks and can generate immediate catastrophic effects as well as directional and anisotropic damage that affect long-term weathering processes. Temperature increase is the most relevant factor, among other components in a fire, generating mineral transformations and bulk mechanical damage. Mineralogical changes at high temperatures are key to understanding the overall mechanical behaviour. However, most studies to date were carried out after rock specimens were heated to a target temperature and cooled down to room temperature. Therefore, these studies are missing the observation of the actual mineral processes during heating. This paper aims to compare mineralogical changes in crystalline rocks during heating by means of XPS and different XRD techniques. Samples of four different granitoids were heated to several temperatures up to 1000 °C to evaluate their chemical and structural changes. Results show how standardised thermal expansion coefficients are not a suitable indicator of the bulk effect of high temperatures on rocks. Results also show how thermal expansion estimations from XRD lattice measurements may be an alternative to bulk dilatometric tests, as they can be performed with limited sampling, which may be necessary in some studies. Nevertheless, XRD and XPS results need to be interpreted carefully in relation to the bulk effects of temperature increase in the rocks, as the structural behaviour may seemingly contradict the macroscopic effect.

Evaluation of the impact of transgenic maize BT799 on growth, development and reproductive function of Sprague-Dawley rats in three generations

BT799 was Bacillus thuringiensis-genetic modified (GM) maize, and Sprague-Dawley (SD) rats were treated with different diet formulations containing BT799 maize grain (33% and 66%) or its non-transgenic Zhengdan 958 (ZD958, 33% and 66%). The feeding lasted for 10 (P)/14 (F1 and F2) weeks. The reproductive capacity and pathological responses were detected in each generation of rats fed with BT799 and ZD958. During the growth and development of parental rats, each group showed the same trend in body weight gain and food intake, with a few fluctuations at individual time points. No statistically significant difference was observed in reproductive data (copulation index, fertility index, and live birth rate) of rats fed with transgenic maize compared with non-transgenic maize. We observed some apparent changes in reproductive data (sperm numbers and motility) and pathological responses (organ relative weights, hematological parameters, serum chemistry parameters, and sex hormone levels) among rats fed with BT799 maize grain. However, these differences were within the laboratory's historical normal range of control SD rats and not maize grain dose-dependent. These changes were not considered to be adverse or toxic. No significant difference in macroscopic or histological adverse effects was observed between rats consuming transgenic BT799 diet and non-transgenic diet. In conclusion, the long-term intake of BT799 maize was as safe as the corresponding non-transgenic maize for three-generation SD rats.

Multistimuli-Responsive Dynamic Effects in a One-Dimensional Coordination Polymer

The development of multistimuli-receptive actuators demands a rational combination of suitable functionalities. Achieving such actuating properties in a single crystalline material is a challenge. In spite of several investigations on photo-, thermo,- and mechano-responsive crystals, single crystalline material displaying all these effects is rare. By a judicious combination of photoreactive 2-fluoro-4′-styrylpyridine units and flexible Pb3(SCN)3 units, a multistimuli-responsive one-dimensional (1D) coordination polymer (CP) showing all these dynamic effects has been fabricated. Single crystals of the CP display rapid ballistic events upon ultraviolet (UV) irradiation triggered by [2 + 2] cycloaddition of photoreactive ligands. In addition, macroscopic jumping, bending, and splitting of the crystals were observed during both heating and cooling cycles because of reversible phase transition. Further, slender crystals of the CP exhibit elastic deformation upon the application of mechanical force. With handful of examples of CPs show macroscopic dynamic effects, this CP paves the way for designing multistimuli-responsive multisalient actuating materials.

Detailed study of quantum path interferences in high harmonic generation driven by chirped laser pulses

We investigate the electron quantum path interference (QPI) effects during high harmonic generation in atomic gas medium driven by ultrashort chirped laser pulses. To achieve that, we identify and vary the different experimentally relevant control parameters of such a driving laser pulse influencing the high harmonic spectra. Specifically, the impact of the pulse duration (from the few-cycle to the multi-cycle domain), peak intensity and instantaneous frequency is studied in a self-consistent manner. Simulations involving macroscopic propagation effects are also considered. The study aims to reveal the microscopic background behind a variety of interference patterns capturing important information both about the fundamental laser field and the generation process itself. The results provide guidance towards experiments with chirp control as a tool to unravel, explain and utilize the rich and complex interplay between QPIs including the tuning of the periodicity of the intensity dependent oscillation of the harmonic signal, and the curvature of spectrally resolved Maker fringes.

Responses of the Mediterranean seagrass Cymodocea nodosa to combined temperature and salinity stress at the ionomic, transcriptomic, ultrastructural and photosynthetic levels

The Little Neptune grass Cymodocea nodosa is a key seagrass species in the Mediterranean Sea, forming extensive and patchy meadows in shallow coastal and transitional ecosystems. In such habitats, high temperatures and salinities, separately and in combination, can be significant stressors in the context of climate change, particularly during heatwave events, and seawater desalination plant effluents.Despite well-documented negative, macroscopic effects, the underlying cellular and molecular processes of the combined effects of increasing temperature and salinities have remained largely elusive in C. nodosa – which are addressed by the present study. High salinity and high temperature, alone and in combination, affected ion equilibrium in the plant cells. Non-synonymous mutations marked the transcriptomic response to salinity and temperature stress at loci related to osmotic stress. Cell structure, especially the nucleus, chloroplasts, mitochondria and organization of the MT cytoskeleton, was also altered. Both temperature and salinity stress negatively affected photosynthetic activity as evidenced by ΔF/Fm’, following an antagonistic interaction type.Overall, this study showed that all biological levels investigated were strongly affected by temperature and salinity stress, however, with the latter having more severe effects. The results have implications for the operation of desalination plants and for assessing the impacts of marine heat waves.

Experimental and simulation study of the interaction characteristics of nano‐MgO and smoke in the fire of a ship engine room

SummaryThe engine room of ships with poor ventilation has high concentrations of accumulated smoke during the fires. In some ways, the existing forced ventilation and water mist fire extinguishing can aggravate the occurrence of back‐burning and flame strengthening. In this article, a novel way to control smoke is proposed. Based on nano‐MgO particles, the adsorption mechanism of MgO at different temperatures (300–500 K) was simulated and analyzed using the Monte Carlo method. And the macroscopic adsorption effects of smoke at different angles (30°, 80°, and 110°) of nano‐MgO vertical spray were studied in a closed confined space of 1.5 × 1.5 × 1 m3, where the diesel oil was used as a fire source. The results show that the nano‐MgO have a good dissipation effect on the fire smoke through the analysis of the temperature, smoke concentration and adsorption amount in the confined space, which can effectively reduce the smoke concentration and improve the visibility in the space. The adsorption effect of nano‐MgO is the best when the spray angle is 30°, the adsorption effect of nano‐MgO is the largest when the pressure is 300 KPa and the temperature is 300 K. Besides, the adsorption of nano‐MgO and carbon smoke particles changed from single‐layer to multilayer adsorption in the process of interaction. The research results provide a theoretical basis for the application of nano‐MgO particles in smoke control of the fire in the ship engine room.

Recent advances of dynamic molecular crystals with light-triggered macro-movements

Dynamic molecular crystals showing light-triggered macro-movements have attracted great attention due to their unique ability for light–force conversion. These molecular crystals are driven remotely without any intermediary devices like wires and motors, which can transform light energy into mechanical work directly. However, the limited space restricts molecular rotation and motion in the crystalline state; thus, realizing macro-movements in molecular crystal systems is still a formidable challenge. In this review, we aim to focus on the underlying working mechanism of the photo-controllable macroscopic motion of molecular crystals with special focus on their practical applications. In detail, we discuss the basic principles and macroscopic photomechanical effects of these dynamic molecular crystals, including their deformation (i.e., bending, twisting, curling); complex motion (i.e., crawling, rotating, rolling); and disintegration (i.e., photosalient effect). Then, we introduce the most promising applications of photomechanical molecular crystals in the fields of all-optical devices, crystal actuators, and biomimetic artificial muscles. Therefore, this review will provide inspiration to develop state-of-the-art dynamic molecular crystals by bridging the disciplines of physics, chemistry, and engineering science.

Numerical calculation of the particle–fluid–particle stress in random arrays of fixed particles

The phase interaction force in a multiphase flow is decomposed into a particle-mean field force and a divergence of a Particle-Fluid-Particle (PFP) stress. The particle mean field force is mainly accounted for through drag models, while the PFP stress arising from the interparticle interactions is seldom reported. Using the nearest particle statistics, the PFP stress is calculated from particle-resolved simulations. The PFP stress represents the macroscopic effect of the drafting-kissing-tumbling mechanism.

Mean-field approximations of networks of spiking neurons with short-term synaptic plasticity.

Low-dimensional descriptions of spiking neural network dynamics are an effective tool for bridging different scales of organization of brain structure and function. Recent advances in deriving mean-field descriptions for networks of coupled oscillators have sparked the development of a new generation of neural mass models. Of notable interest are mean-field descriptions of all-to-all coupled quadratic integrate-and-fire (QIF) neurons, which have already seen numerous extensions and applications. These extensions include different forms of short-term adaptation considered to play an important role in generating and sustaining dynamic regimes of interest in the brain. It is an open question, however, whether the incorporation of presynaptic forms of synaptic plasticity driven by single neuron activity would still permit the derivation of mean-field equations using the same method. Here we discuss this problem using an established model of short-term synaptic plasticity at the single neuron level, for which we present two different approaches for the derivation of the mean-field equations. We compare these models with a recently proposed mean-field approximation that assumes stochastic spike timings. In general, the latter fails to accurately reproduce the macroscopic activity in networks of deterministic QIF neurons with distributed parameters. We show that the mean-field models we propose provide a more accurate description of the network dynamics, although they are mathematically more involved. Using bifurcation analysis, we find that QIF networks with presynaptic short-term plasticity can express regimes of periodic bursting activity as well as bistable regimes. Together, we provide novel insight into the macroscopic effects of short-term synaptic plasticity in spiking neural networks, as well as two different mean-field descriptions for future investigations of such networks.