Diffusion Speed Research Articles

Laboratory simulation on drifting of hazardous chemical substance

The continuously increase of hazardous chemicals transportation leads to a high risk of chemicals leakage. Researches on drifting of chemical substances are of vital importance in damage reducing. Laboratory simulation on drifting of hazardous chemical substance carried out inside a wave tank at the Shandong Provincial Key Laboratory. Different environmental conditions (wind, wave, etc.) were simulated in the wave tank to find out the influence of these factors on substance drifting and diffusion. To identify the difference between hazardous substance, floating ball and dyed petroleum oil were used to simulate solid and liquid floating hazardous chemical substance. The result revealed that wave can improve diffusion, the diffusion speed varies with wave height. Wind can drive surface substance, the drifting coefficient ranges from 2.1% to 3.0%, while liquid drifting coefficient is relatively larger. The laboratory results provide a basis for the study on the drifting and diffusion of hazardous chemicals at sea. Meanwhile, the coefficient could be applied as a correction in numerical models to improve prediction accuracy.

COVID ‐19 transmission in cold chain: A safe and green new‐generation cold chain is demanded

<scp>COVID</scp> ‐19 transmission in cold chain: A safe and green new‐generation cold chain is demanded

Regionalization for infection control: An algorithm for delineating containment zones considering the regularity of human mobility

Restricting human movement to decrease contact probability and frequency helps mitigate large-scale epidemics. Movement-based zoning can be implemented to delineate the boundaries for movement restrictions. Previous studies used network community detection methods, which capture cohesive within-region movements, to delineate containment zones. However, most people usually travel and spend most of their time in several fixed locations, which implies that an infected person could transmit the pathogens to only a specific group of people with whom s/he usually has a contact in frequently-visited locations. Existing network community detection methods cannot reflect the regularity of the flow of people; thus, this study aims to use land-use patterns to reflect trip purposes to measure the regularity of human mobility. We propose a novel network community detection method, the Human Mobility Regularity-based Zoning (HuMoRZ) algorithm, to delineate containment zones incorporating mobility regularity. The Taipei metropolitan area in Taiwan is used to demonstrate the feasibility of the proposed algorithm. The spatial diffusion of an emerging respiratory disease, novel influenza A/H1N1, is simulated for comparing three different quarantine zoning systems: (1) a minimum zoning unit, (2) optimal zoning without considering mobility regularity, and (3) optimal zoning considering mobility regularity. Two epidemiological performance indicators are used to compare simulation results: namely, the accumulated infected number (AN) on the 30th day, reflecting the severity of an epidemic, and the critical time (CT), the moment at which half of the population becomes infected, measuring the diffusion speed of an epidemic. To measure the variety of different facility types within a containment zone, we further use Shannon's entropy scores, representing a self-contained zone, and the boxplot of all zones' entropy scores, reflecting geospatial homogeneity of life functions across zones. Our results suggest that containment zones that incorporate mobility regularity could significantly delay the epidemic peak and critical time and decrease the severity of an epidemic. The zoning patterns proposed in our algorithm could also allow for more life functions in a zone and more evenly distributed life resources across zones than those of zones generated by other methods. These findings could provide insightful implications for fighting the COVID-19 pandemic.

Dynamics of diffusive cell signaling relays.

In biological contexts as diverse as development, apoptosis, and synthetic microbial consortia, collections of cells or subcellular components have been shown to overcome the slow signaling speed of simple diffusion by utilizing diffusive relays, in which the presence of one type of diffusible signaling molecule triggers participation in the emission of the same type of molecule. This collective effect gives rise to fast-traveling diffusive waves. Here, in the context of cell signaling, we show that system dimensionality - the shape of the extracellular medium and the distribution of cells within it - can dramatically affect the wave dynamics, but that these dynamics are insensitive to details of cellular activation. As an example, we show that neutrophil swarming experiments exhibit dynamical signatures consistent with the proposed signaling motif. We further show that cell signaling relays generate much steeper concentration profiles than does simple diffusion, which may facilitate neutrophil chemotaxis.

Network modularity controls the speed of information diffusion.

The rapid diffusion of information and the adoption of social behaviors are of critical importance in situations as diverse as collective actions, pandemic prevention, or advertising and marketing. Although the dynamics of large cascades have been extensively studied in various contexts, few have systematically examined the impact of network topology on the efficiency of information diffusion. Here, by employing the linear threshold model on networks with communities, we demonstrate that a prominent network feature-the modular structure-strongly affects the speed of information diffusion in complex contagion. Our simulations show that there always exists an optimal network modularity for the most efficient spreading process. Beyond this critical value, either a stronger or a weaker modular structure actually hinders the diffusion speed. These results are confirmed by an analytical approximation. We further demonstrate that the optimal modularity varies with both the seed size and the target cascade size and is ultimately dependent on the network under investigation. We underscore the importance of our findings in applications from marketing to epidemiology, from neuroscience to engineering, where the understanding of the structural design of complex systems focuses on the efficiency of information propagation.

The Dominant Nodes Index in Shortest Paths (DNISP) as A Local Measure of Source Looking for the Target in Complex Networks

&lt;p&gt;When there are multiple alternate shortest paths between any two nodes in a complex network, there is a need to know details about the content of the paths and the dominance of the nodes within it, this need comes to maximize, control and speed of the information diffusion. This paper discusses the creation of a new special measure as a local scale for any X node in the network. This measure will give each neighbour of the node X a domination value to access the rest of the network, in other words any nodes included in the shortest path (X,Y) will be given a control value, taking into account the existence of more than one shortest path between (X,Y). Such a measure is called a DNISP, which stands for Dominant Nodes Index in Shortest Paths. The X-node needs to examine all shortest paths that connect it with any other nodes across the ones that are directly associated with it. This measure provides an insight into how information flows between nodes according to dominant values with each node.&lt;/p&gt;

Beat-by-Beat Cardiomyocyte T-Tubule Deformation Drives Tubular Content Exchange.

The sarcolemma of cardiomyocytes contains many proteins that are essential for electromechanical function in general, and excitation-contraction coupling in particular. The distribution of these proteins is nonuniform between the bulk sarcolemmal surface and membrane invaginations known as transverse tubules (TT). TT form an intricate network of fluid-filled conduits that support electromechanical synchronicity within cardiomyocytes. Although continuous with the extracellular space, the narrow lumen and the tortuous structure of TT can form domains of restricted diffusion. As a result of unequal ion fluxes across cell surface and TT membranes, limited diffusion may generate ion gradients within TT, especially deep within the TT network and at high pacing rates. We postulate that there may be an advective component to TT content exchange, wherein cyclic deformation of TT during diastolic stretch and systolic shortening serves to mix TT luminal content and assists equilibration with bulk extracellular fluid. Using electron tomography, we explore the 3-dimensional nanostructure of TT in rabbit ventricular myocytes, preserved at different stages of the dynamic cycle of cell contraction and relaxation. We show that cellular deformation affects TT shape in a sarcomere length-dependent manner and on a beat-by-beat time-scale. Using fluorescence recovery after photobleaching microscopy, we show that apparent speed of diffusion is affected by the mechanical state of cardiomyocytes, and that cyclic contractile activity of cardiomyocytes accelerates TT diffusion dynamics. Our data confirm the existence of an advective component to TT content exchange. This points toward a novel mechanism of cardiac autoregulation, whereby the previously implied increased propensity for TT luminal concentration imbalances at high electrical stimulation rates would be countered by elevated advection-assisted diffusion at high mechanical beating rates. The relevance of this mechanism in health and during pathological remodeling (eg, cardiac hypertrophy or failure) forms an exciting target for further research.

Multi‐Level Electro‐Thermal Switching of Optical Phase‐Change Materials Using Graphene

Reconfigurable photonic systems featuring minimal power consumption are crucial for integrated optical devices in real‐world technology. Current active devices available in foundries, however, use volatile methods to modulate light, requiring a constant supply of power and significant form factors. Essential aspects to overcome these issues are the development of nonvolatile optical reconfiguration techniques which are compatible with on‐chip integration with different photonic platforms and do not disrupt their optical performances. Herein, a solution is demonstrated using an optoelectronic framework for nonvolatile tunable photonics that uses undoped‐graphene microheaters to thermally and reversibly switch the optical phase‐change material Ge2Sb2Se4Te1 (GSST). An in situ Raman spectroscopy method is utilized to demonstrate, in real‐time, reversible switching between four different levels of crystallinity. Moreover, a 3D computational model is developed to precisely interpret the switching characteristics, and to quantify the impact of current saturation on power dissipation, thermal diffusion, and switching speed. This model is used to inform the design of nonvolatile active photonic devices; namely, broadband Si3N4 integrated photonic circuits with small form‐factor modulators and reconfigurable metasurfaces displaying 2π phase coverage through neural‐network‐designed GSST meta‐atoms. This framework will enable scalable, low‐loss nonvolatile applications across a diverse range of photonics platforms.

Diffusion of Innovations in Middle Eastern versus Western Markets: A Mathematical Computation Cellular Automata Simulation Model

Simulation modelling has gained ground over the years since it can provide various scenarios applied to any scientific area. In this study, a stochastic cellular automata model is proposed, in which agents fall into three distinct categories (adopters, non-adopters and denials). Based on Hofstede’s cultural dimension individualism, we characterize three major international markets, as perfectly clustered (collective) to perfectly random (individualistic). We investigate innovation diffusion speed, in each network topology. At each time step, the decision of non-adopters to purchase innovative products, is affected by their immediate neighborhood (von Neumman). The speed of diffusion is evaluated using time at which sales reach 50% of market. Effects of simulation parameters on speed of diffusion, are assessed using a log-normal accelerated failure time model. Results demonstrate that diffusion of innovative products accelerates when innovators of a virtual economic system are placed according to a random network and when amount of innovators and imitators in the economic system increases. Slower innovative products’ diffusion process is a result of a large amount of denials and of how imitators are placed in the in the virtual economic system. Diffusion in small-world virtual economic systems lead to small time inflexion points very close to those of a random networked market.

Expansion characteristics of butanol-diesel spray and droplet

Butanol is one of the most promising alternative fuels. This study is conducted focusing on the expansion characteristics of butanol-diesel spray. In this work, a high-speed common rail system is used for generating direct spray, and single droplet of tested fuel is heated, the radial diffusion of the whole spray and the expansion of butanol-diesel droplet are observed and analysed. Results show that the addition of butanol enhances the radial development of butanol-diesel value, while the addition of butanol would bring a little negative effect on the speed of radial diffusion. Additionally, the addition of butanol makes the deformation of the mixed fuel droplets more intense.

Innovation adoption: Broadcasting versus virality

AbstractDiffusion channels are critical to determining the adoption scale, which leads to the ultimate impact of an innovation. The aim of this study is to develop an integrative understanding of the impact of two diffusion channels (i.e., broadcasting vs. virality) on innovation adoption. Using citations of a series of classic algorithms and the time series of co‐authorship as the footprints of their diffusion trajectories, we propose a novel method to analyze the intertwining relationships between broadcasting and virality in the innovation diffusion process. Our findings show that broadcasting and virality have similar diffusion power, but play different roles across diffusion stages. Broadcasting is more powerful in the early stages but may be gradually caught up or even surpassed by virality in the later period. Meanwhile, diffusion speed in virality is significantly faster than broadcasting and members from virality channels tend to adopt the same innovation repetitively.

Effects of local nonequilibrium in rapid eutectic solidification—Part 1: Statement of the problem and general solution

Numerous experimental data on the rapid solidification of eutectic systems exhibit the formation of metastable solid phases with the initial (nominal) chemical composition. This fact is explained by suppression of eutectic decomposition due to diffusionless (chemically partitionless) solidification beginning at a high but a finite growth velocity of crystals. A model considering the diffusionless growth is developed in the present work to analyze the atomic diffusion ahead of lamellar eutectic couples growing into supercooled liquid. A general solution of the model is presented from which two regimes are followed. The first presents a diffusion‐limited regime with the existence of eutectic decomposition if the solid–liquid interface velocity is smaller than the characteristic diffusion speed in the bulk liquid. The second shows suppression of eutectic decomposition under diffusionless transformation from liquid to one‐phase solid if the solid–liquid interface velocity overcomes characteristic diffusion speed in the bulk liquid.

A novel indoor smell regulation method

Indoor smell affects human health and work efficiency. In order to reduce the impact of indoor smell on human health and work efficiency, a novel indoor smell regulation method was proposed. First, an indoor smell regulation system, including wireless sensor nodes (WSNs), a smell presenting device (SPD), and a wireless control node, was designed. Second, the number and location of WSNs were optimized by combining the computational fluid dynamics with the ant colony optimization algorithm. Third, the location of the SPD was determined according to the diffusion speed, uniformity of distribution, total number of indoor smell particles, and average smell concentration of the breathing section. Finally, experiments were conducted and the results show that the smell regulation system can quickly and effectively detect and remove the unpleasant smell and then release the pleasant smell. Generally, the smell regulation system is capable of performing an indoor smell adjustment in less than 5 min.

Study on Gas Diffusion in Fire Working Areas of Oil and Gas Pipelines Based on Temperature Difference.

When a pipeline is under fire safety work construction, the stack effect of the pipeline will increase the diffusion rate of nitrogen, reduce the oxygen content, and cause asphyxia. To prove the influence of the stack effect of the pipeline on the nitrogen movement in the pipeline and put forward effective ventilation control measures, the formation mechanism, gas diffusion law, and ventilation parameters of the stack effect of the oil and gas pipelines are studied through theoretical derivation and numerical simulation. The results show that the nitrogen concentration at the height of the breathing zone in the hot zone first increases and then decreases along the axial distance. The larger the temperature difference, the faster the diffusion speed of nitrogen in the fire safety work area, and the lower the oxygen concentration. When the temperature difference increases to 30 °C, the maximum oxygen concentration in the work area is 0.177; to control the problem of low oxygen content caused by the stack effect, three ventilation schemes are put forward. Through the analysis that installing fans symmetrically on both sides, 4 m away from the pipe opening, can effectively reduce the stack effect intensity when the optimal working wind speed of the fan is 4 m/s. The findings of this study can help in better understanding the causes of the chimney effect during pipeline fire safety work and provide theoretical basis for controlling personnel suffocation caused by the chimney effect.

NGF induces pulmonary arterial hyperreactivity through Connexin 43 increased expression

We have previously shown that the nerve growth factor (NGF) plays a critical role in pathophysiology of pulmonary hypertension (PH) by promoting pulmonary arterial (PA) inflammation, remodelling and hyperreactivity. To characterize mechanisms activated by NGF to induce PA hyperreactivity, focusing on Connexin 43 (Cx43), a gap junction protein essential for vascular reactivity. Expression of NGF and its TrkA receptor were evaluated by Western blotting in human PA smooth muscle cells (hPASMC) from controls or from patients suffering from idiopathic pulmonary arterial hypertension (IPAH). In cells treated or not with NGF (0.1-100 ng/ml, 24 h), Cx43 expression and localisation were evaluated by Western blotting, immunofluorescence and cell surface biotinylation. Gap junction activity was assessed by Lucifer yellow (LY) dye transfer assay. Contractions of control rat PA were induced by phenylephrine (PHE, 10-10-10-4 M) in absence or presence of NGF (100 ng/ml, 24 h). The role of Cx43 in NGF-induced rat PA reactivity was evaluated by use of 43Gap26 (Cx43 blocking peptide, 300 μM), or an anti-Cx43 siRNA (10nmol IV). NGF and TrkA expression were increased in hPASMC from IPAH patients compared to controls. NGF increased Cx43 expression in hPASMC from both controls and IPAH patients, but with a higher sensitivity in IPAH cells (maximum at 1 ng/ml vs. 100 ng/ml). This increase was abolished after treatment with K252a (TrkA kinase inhibitor). In control hPASMC, NGF increased Cx43 plasma membrane localisation and LY diffusion speed through Gap junctions. NGF-induced PA hyperreactivity to PHE was inhibited ex vivo by treatment with 43Gap26 and in vivo after administration of Cx43 siRNA. NGF pathway is unregulated in IPAH cells. NGF increases Cx43 PA expression through activation of its TrkA receptor. Cx43 increased expression at hPASMC plasma membrane upregulates gap junction activity, thus promoting NGF-induced PA hyperreactivity.

Nonlinear Dynamic Analysis of New Product Diffusion considering Consumer Heterogeneity

When a new product enters the market, individual consumers’ decision-making behavior and purchase time are uncertain. Based on the dynamics of epidemic transmission theory and agent modeling technology, this study proposes a new coupling model through the combination of the improved SEIR epidemic model and the heterogeneous agent model. This model considers consumer heterogeneity resulting from three aspects in consumers’ sensitivity, network topology, and considerations of information flow received. It aims to analyze how consumer heterogeneity affects the scale and speed of new product diffusion. The proposed model showed that consumers’ characteristics and behavior combination at the microlevel lead to the diversity of nonlinear diffusion curves at the macrolevel for new products. Moreover, a pilot study is conducted to simulate this model and examine how to estimate the model’s parameters using aggregated data about film products. The pilot study results suggested that different consumer characteristics and behavior combinations affect the scale and speed of new product diffusion to varying degrees. In different scenarios, there were significant differences in the influence of the degree of consumer heterogeneity on diffusion, accompanied by the occurrence of threshold. The results of the empirical analysis in this study are in line with reality.

Formulasi Kebijakan Roadmap Inovasi Daerah di Kabupaten Bekasi

Bekasi Regency is the area with the largest industrial area in Southeast Asia, where there are 16 industrial areas with relatively large land area. In addition, there are also seven large industrial zones or industrial zones on an international scale, in line with this, the problem of public service delivery in the Bekasi District Government must be carried out properly to the public. In optimizing the public services, various innovative ideas and ideas are needed to create synergy and efficiency in the provision of these public services. In this study, the innovation system is a unified component that influences the direction of development and speed of innovation, diffusion, and learning processes in the development, mastery, advancement and application/utilization of science and technology. How sub-subsystems (elements / factors) play their roles, their interrelations (including policy coherence), and the dynamics of their interactions determine or influence the dynamic performance of innovation systems. Strengthening the innovation system means structuring the system (holistic, simultaneous, systemic issues) in a structured way. In a policy perspective, strengthening innovation systems means remedial steps that need to be directed to address systemic failures. Therefore, policy strategies need to be developed as a unified innovation policy framework (KKI) to strengthen the system.

Study on the coupling evolution of air and temperature field in coal mine goafs based on the similarity simulation experiments

In order to prevent the occurrence of the coupling disaster between coal spontaneous combustion and gas explosion, the similarity simulation experiments for coal mine goaf were carried out with or without heat source on the scaled-down experimental platform. Results show that the O2 diffusion speed in strike direction at the air inlet side is significantly greater than that on the air return side, especially under the condition of high ventilation velocity. The higher the ventilation velocity, the greater the risk of coal spontaneous combustion. O2 consumption and thermal convection in the coal spontaneous combustion area make it difficult for O2 to migrate to the deeper goaf. Part of the O2 in air is affected by the chimney effect, rose into the spaces formed by the caving rocks and continuously mixes with the CH4 accumulated in these spaces. Meanwhile, high-temperature area tends to expand in the direction of fresh air leakage in the process of coal spontaneous combustion in the goaf. The formed explosive gases may explode during the migration of high-temperature area, resulting in disaster accidents. Therefore, the temperature change at the location where the air leakage is serious in the goaf should also be monitored in time to prevent the coal spontaneous combustion hazards.

The diffusion of electric mobility in the European Union and beyond

This paper studies the diffusion process of battery electric vehicles (BEVs) in the European Union and beyond. Based on a logistic technology diffusion model, growth processes described by S-curves are predicted for a selction of 18 EU countries and five additional benchmark countries worldwide. This paper shows that for fixed upper bounds of the diffusion process, the investigated countries differ in terms of predicted diffusion speeds. Thus, the time for them to reach saturation in the number of adopters varies as well. In order to understand these different diffusion processes and their determinants, the factors influencing the diffusion speed in a subsample of 14 European countries are empirically analyzed. In addition to investigating country fixed effects and socio-economic factors, this paper focuses on government incentives and their impact on the diffusion rate. The paper reveals that financial incentives in the form of purchase price advantages do play an important role in this context. At the same time, the analysis does not confirm a significant impact of tax regulations and non-financial incentives on the diffusion speed.

Comparison of three in-situ gels composed of different oil types

A phospholipid-based phase separation in-situ gel (PPSG) system, which consists of phospholipids, medium chain oil (triglyceride) and ethanol as basic ingredients, has been previously developed in our lab. In addition, glycerol monooleate (monoglyceride) and glycerol dioleate (diglyceride) were also reported to be able to form liquid crystal gels. Monoglyceride, diglyceride and triglyceride have different degrees of hydroxyl substitution in glycerol and therefore different amphiphilic properties, which may cause different properties of gels composed of them. In this experiment, glycerol monooleate (GMO), glycerol dioleate (GDO) and glycerol trioleate (GTO) were selected to prepare three kinds of PPSGs. We systematically studied their in-vitro and in-vivo physicochemical properties and investigated their drug release behavior with octreotide (OCT) as the model drug. The results showed that PPSG composed of GTO (GTO-gel) had a different microstructure, a slower solvent diffusion speed and the less irritation to skin. In addition, the drug release result showed that the GTO-gel group had a lower initial release rate and a more stable release profile. All results above indicated that GTO-gel had a greater potential as a drug delivery system.