Diffusion Process Research Articles

Cascade genetic testing: an underutilized pathway to equitable cancer care?

The Precision Medicine Initiative was launched upon the potential of genomic information to tailor medical care. Cascade genetic testing represents a powerful application of precision medicine and involves the process of familial diffusion or the "cascade" of genomic risk information. When an individual (proband) is found to carry a cancer-associated germline pathogenic mutation, the information should be cascaded or shared with at-risk relatives. First degree relatives have a 50% likelihood of carrying the same cancer-associated mutation. This process of cascade testing offers at-risk relatives the opportunity for genetic testing and, for those who also carry the cancer-associated mutation, genetically targeted primary disease prevention through intensive cancer surveillance, chemoprevention and risk-reducing surgery, reducing morbidity and preventing mortality. Cascade testing has been designated by the Centers for Disease Control and Prevention as a Tier 1 genomic application for hereditary breast and ovarian cancer. In this manuscript we describe a cascade genetic testing and in particular focus on its potential to provide necessary care to medically underserved and vulnerable populations.

Metal Organic Frameworks as Polysulfide Reaction Modulators for Lithium Sulfur Batteries: Advances and Perspectives.

Currently, lithium sulfur (Li-S) battery with high theoretical energy density has attracted great research interest. However, the diffusion and loss process of intermediate lithium polysulfide during charge-discharge hindered the application of the Li-S battery in modern life. To overcome this issue, metal organic frameworks (MOFs) and their composites have been regarded as effective additions to restrain the LiPS diffusion process for Li-S battery. Benefiting from the unique structure with rich active sites to adsorb LiPS and accelerate the LiPS redox, the Li-S batteries with MOFs modified exhibit superior electrochemical performance. Considering the rapid development of MOFs in Li-S battery, this review summarizes the recent studies of MOFs and their composites as the sulfur host materials, functional interlayer, separator coating layer, and separator/solid electrolyte for Li-S batteries in detail. In addition, the promising design strategies of functional MOF materials are proposed to improve the electrochemical performance of Li-S battery.

Structural, bacteriostatic and antioxidant profiling of zinc oxide nanoparticles

The bacterial infection and generation of free radicals inside the body are serious threats to human health globally and researchers show their serious concern for these issues. Thus, in this study, an attempt has been made to control bacterial growth and scavenge the ABTs free radicals. ZnO-NPs were synthesized by an economical method, and the characteristics were investigated using a range of analytical techniques. These methods included FTIR, SEM, EDX, XRD, and TEM. The agar-well diffusion process has been followed to control the growth of selected bacteria and the ABTs free radicals have been scavenged using a standard protocol. The effect of the dose on both activities has been studied where the results has explore that the effectiveness of the ZnO-NPs gradually increases with increasing concentration.

Diffusion in Porous Rock Is Anomalous.

Molecular diffusion of chemical species in subsurface environments─rock formations, soil sediments, marine, river, and lake sediments─plays a critical role in a variety of dynamic processes, many of which affect water chemistry. We investigate and demonstrate the occurrence of anomalous (non-Fickian) diffusion behavior, distinct from classically assumed Fickian diffusion. We measured molecular diffusion through a series of five chalk and dolomite rock samples over a period of about two months. We demonstrate that in all cases, diffusion behavior is significantly different than Fickian. We then analyze the results using a continuous time random walk framework that can describe anomalous diffusion in heterogeneous porous materials such as rock. This methodology shows extreme long-time tailing of tracer advance as compared to conventional Fickian diffusion processes. The finding that distinct anomalous diffusion occurs ubiquitously implies that diffusion-driven processes in subsurface zones should be analyzed using tools that account for non-Fickian diffusion.

Revisiting the bleeding effect in historical cobalt porcelain pigments: Mechanism, influence and technical responses

The bleeding phenomenon, a persistent and widespread issue in the application of cobalt-bearing pigment during porcelain decoration, has spurred different civilisations to develop various response strategies to alleviate this problem. In this study, we challenge the prevailing hypotheses concerning the role of composition and viscosity in determining the bleeding effect on blue-and-white wares, proposing a novel physical model framing it as a diffusion process that occurs within vitreous silicate, where the severity can be qualitatively expressed using the diffusion distance. Drawing upon the phenomenological Fick's law and microscopic diffusion mechanism, we quantitatively discuss the primary physical parameters that influence the diffusion behaviour for the first time, clarifying that the diffusion of cobalt ions is not related to the medium viscosity. Moreover, compared with the microstructural features of blue decors with and without the bleeding effect, we reveal that domestic cobalt particles are all encapsulated by anorthite crystals, acting as a passivation shell to hinder the dissolution of cobalt particles. Significantly, our reinterpretation has broader archaeological implications for the bleeding effect associated with cobalt pigment in ceramics, elucidating the historical trajectories of responsive practices and the multifaceted interplay between resource form, artistic expression and technological advancement across varying environmental and cultural contexts. Overall, these responses to the bleeding effect exemplify the complexities of technological evolution, highlighting that technology is not merely an extension of technical knowledge but also functions as a form of social construction deeply intertwined with its local context. This comprehensive understanding contributes to our understanding of historical narratives in ceramics and the diversity of human ingenuity in ancient societies, with potential implications for contemporary pigment manufacture.

High critical current properties of multi-filamentary MgB2 superconducting wires fabricated by an internal Mg diffusion method

Abstract Although both mass density and grain connectivity of MgB2 superconducting layers can be greatly improved through an internal Mg diffusion (IMD) process, poor structure uniformity and low MgB2 filling factor of IMD wires limit further enhancement of their superconducting performance. Herein we prepared 19-filament and 37-filament IMD-MgB2 superconducting wires by a combination of optimizing the component structure and introducing the intermediate annealing process. The microstructure analysis suggests that well structure uniformity and high layer density have been achieved in multi-filamentary MgB2 wires; and the MgB2 filling factor reaches up to 9.3-11.0%. The magnetic superconducting transition of MgB2 wires is relatively sharp and the onset Tc is around 37 K. Remarkably, there is no magnetic flux jump for 37-filament wires in low field region at 5 K. At 4.2 K and 4 T, the transport layer Jc values of 19-filament and 37-filament MgB2 wires are as high as 1.5×105 A/cm2 and 2.2×105 A/cm2, respectively, and accordingly engineering Je of 1.7×104 A/cm2 and 2.0×104 A/cm2. These results indicate that the performance of multi-filamentary IMD-MgB2 wires can compete with the traditional PIT-MgB2 wires as applied in the industry.

On V-Geometric Ergodicity Markov Chains of the Two-Inertia Systems

This study employs the diffusion process to construct Markov chains for analyzing the common two-inertia systems used in industry. Two-inertia systems are prevalent in commonly used equipment, where the load is influenced by the coupling of external force and the drive shaft, leading to variations in the associated output states. Traditionally, the control of such systems is often guided by empirical rules. This paper examines the equilibrium distribution and convergence rate of the two-inertia system and develops a predictive model for its long-term operation. We explore the qualitative behavior of the load end at discrete time intervals. Our findings are applicable not only in control engineering, but also provide insights for small-scale models incorporating dual-system variables.

Hot Carrier Trapping and It's Influence to the Carrier Diffusion in CsPbBr3 Perovskite Film Revealed by Transient Absorption Microscopy.

The defects in perovskite film can cause charge carrier trapping which shortens carrier lifetime and diffusion length. So defects passivation has become promising for the perovskite studies. However, how defects disturb the carrier transport and how the passivating affects the carrier transport in CsPbBr3 are still unclear. Here the carrier dynamics and diffusion processes of CsPbBr3 and LiBr passivated CsPbBr3 films are investigated by using transient absorption spectroscopy and transient absorption microscopy. It's found that there is a fast hot carrier trapping process with the above bandgap excitation, and the hot carrier trapping would decrease the population of cold carriers which are diffusible, then lower the carrier diffusion constant. It's proved that LiBr can passivate the defect and lower the trapping probability of hot carriers, thus improve the carrier diffusion rate. The finding demonstrates the influence of hot carrier trapping to the carrier diffusion in CsPbBr3 film.

Humidity impact on polarization dynamics in polymer electrolyte membrane fuel cells through distribution of relaxation times analysis

The interaction among relative humidity, current density, and internal polarization plays a crucial role in optimizing the performance of polymer electrolyte membrane fuel cells (PEMFCs). However, achieving swift analysis and feedback on the internal humidity status of PEMFCs through on-vehicle impedance spectroscopy measurements remains a significant challenge. Conducting a series of impedance spectra under operating conditions of 30 %, 50 %, and 80 % relative humidity sheds light on the impact of humidity on performance. Correlations between specific distribution of relaxation times (DRT) peaks and internal polarization are established. Through DRT analysis, four polarization dynamics related to proton transfer at the proton exchange membrane interface, proton transport in the cathode catalyst layer, charge transfer, and the oxygen diffusion process are effectively identified based on characteristic frequencies and peaks. The rate-determining step of the polarization varies under idling, rated, and overload conditions, providing valuable insights. This study contributes analytical models and strategic guidance for tailoring relative humidity conditions to mitigate polarization, thereby enabling real-time control and enhancement of PEMFC performance.

Molecular Autonomous Pathfinder Using Deep Reinforcement Learning.

Diffusion in solids is a slow process that dictates rate-limiting processes in key chemical reactions. Unlike crystalline solids that offer well-defined diffusion pathways, the lack of similar structural motifs in amorphous or glassy materials poses great challenges in bridging the slow diffusion process and material failures. To tackle this problem, we propose an AI-guided long-term atomistic simulation approach: molecular autonomous pathfinder (MAP) framework based on deep reinforcement learning (DRL), where the RL agent is trained to uncover energy efficient diffusion pathways. We employ a Deep Q-Network architecture with distributed prioritized replay buffer, enabling fully online agent training with accelerated experience sampling by an ensemble of asynchronous agents. After training, the agents provide atomistic configurations of diffusion pathways with their energy profile. We use a piecewise nudged elastic band to refine the energy profile of the obtained pathway and the corresponding diffusion time on the basis of transition-state theory. With the MAP framework, we demonstrate atomistic diffusion mechanisms in amorphous silica with time scales comparable to experiments.

Effect of Micro-Cracks on Chloride Ion Diffusion in Concrete Based on Stochastic Aggregate Approach

For concrete structures in offshore areas, chloride ion erosion is one of the main factors affecting durability. It is crucial to evaluate the chloride ion permeability resistance of concrete structures. In this paper, a finite element simulation of the chloride ion diffusion process in concrete is conducted. A mass diffusion finite element model based on a random aggregate approach is established to investigate the influences of an aggregate, the interface transition zone, and micro-cracks on the chloride ion diffusion coefficients in concrete. The results show that the mass diffusion finite element analysis based on the exponential function model and the power function model can effectively simulate the chloride ion diffusion process in concrete. In addition, the data reveal that volume fraction and distribution aggregates considerably affect chloride ion diffusivity in concrete. Also, the interface transition zone significantly accelerates chloride ion diffusion in concrete. Moreover, this acceleration effect exceeds the barrier effect of an aggregate.

Cation Distribution and Anion Transport in the La3Ga5-xGe1+xO14+0.5x Langasite Structure.

Exploration of compositional disorder using conventional diffraction-based techniques is challenging for systems containing isoelectronic ions possessing similar coherent neutron scattering lengths. Here, we show that a multinuclear solid-state Nuclear Magnetic Resonance (NMR) approach provides compelling insight into the Ga3+/Ge4+ cation distribution and oxygen anion transport in a family of solid electrolytes with langasite structure and La3Ga5-xGe1+xO14+0.5x composition. Ultrahigh field 71Ga Magic Angle Spinning (MAS) NMR experiments acquired at 35.2 T offer striking resolution enhancement, thereby enabling clear detection of Ga sites in different coordination environments. Three-connected GaO4, four-connected GaO4 and GaO6 polyhedra are probed for the parent La3Ga5GeO14 structure, while one additional spectral feature corresponding to the key (Ga,Ge)2O8 structural unit which forms to accommodate the interstitial oxide ions is detected for the Ge4+-doped La3Ga3.5Ge2.5O14.75 phase. The complex spectral line shapes observed in the MAS NMR spectra are reproduced very accurately by the NMR parameters computed for a symmetry-adapted configurational ensemble that comprehensively models site disorder. This approach further reveals a Ga3+/Ge4+ distribution across all Ga/Ge sites that is controlled by a kinetically governed cation diffusion process. Variable temperature 17O MAS NMR experiments up to 700 °C importantly indicate that the presence of interstitial oxide ions triggers chemical exchange between all oxygen sites, thereby enabling atomic-scale understanding of the anion diffusion mechanism underpinning the transport properties of these materials.

Multi-plane denoising diffusion-based dimensionality expansion for 2D-to-3D reconstruction of microstructures with harmonized sampling

Acquiring reliable microstructure datasets is a pivotal step toward the systematic design of materials with the aid of integrated computational materials engineering (ICME) approaches. However, obtaining three-dimensional (3D) microstructure datasets is often challenging due to high experimental costs or technical limitations, while acquiring two-dimensional (2D) micrographs is comparatively easier. To deal with this issue, this study proposes a novel framework called ‘Micro3Diff’ for 2D-to-3D reconstruction of microstructures using diffusion-based generative models (DGMs). Specifically, this approach solely requires pre-trained DGMs for the generation of 2D samples, and dimensionality expansion (2D-to-3D) takes place only during the generation process (i.e., reverse diffusion process). The proposed framework incorporates a concept referred to as ‘multi-plane denoising diffusion’, which transforms noisy samples (i.e., latent variables) from different planes into the data structure while maintaining spatial connectivity in 3D space. Furthermore, a harmonized sampling process is developed to address possible deviations from the reverse Markov chain of DGMs during the dimensionality expansion. Combined, we demonstrate the feasibility of Micro3Diff in reconstructing 3D samples with connected slices that maintain morphologically equivalence to the original 2D images. To validate the performance of Micro3Diff, various types of microstructures (synthetic or experimentally observed) are reconstructed, and the quality of the generated samples is assessed both qualitatively and quantitatively. The successful reconstruction outcomes inspire the potential utilization of Micro3Diff in upcoming ICME applications while achieving a breakthrough in comprehending and manipulating the latent space of DGMs.

Spatio-temporal Analysis of the factors affecting NOx concentration during the evaluation cycle of high pollution episodes in Tehran metropolitan

Tehran, the capital of Iran, experiences high levels of pollution, particularly during the cold seasons. Recent studies have shown an increase in the concentration of nitrogen compounds in Tehran. However, the role of advection, deposition, vertical diffusion processes and chemical conversion of NOx in this region requires further investigation. In this study, The Weather Research and Forecasting model with Chemistry (WRF-Chem) was employed to numerically simulate each of these processes during a severe pollution episode in winter from November 28, 2021, to December 8, 2021. During this high pollution episode, the weather conditions were calm, and based on the Air Quality Index (AQI), the air quality was unhealthy for sensitive groups. The presence of a ridge at the 500 hPa level, the placement of a low-level high-pressure cell over the region, and consequently, atmospheric subsidence and low wind speed create favorable conditions for severe pollution events in Tehran. Additionally, temperature inversion during the night and a decrease in the boundary layer height contribute to increased surface NOx concentration during this period. When comparing different processes influencing NOx concentrations, it has been observed that advection has the most significant impact, while dry deposition and chemical conversion have the least effect. On stable days advection increases NOx concentration in central and northeast of Tehran urban area during daytime. The maximum vertical diffusion is observed in the southern and western regions, corresponding to the emission pattern of NO and NO2. The examination of the vertical profile of advection and vertical diffusion shows that vertical diffusion dominates near the surface layer, while advection dominates at higher altitudes in terms of NOx concentration changes. Under unstable conditions (Dec-02), with arrival of the cold front and the influence of convective clouds, the impact of convective transport becomes more pronounced in reducing NOx concentrations in the southern and central regions of Tehran urban area. The highest NOx deposition is observed in the early morning in the southern and southwestern suburban areas of Tehran, correlating with wind direction variations, NOx concentration, and vegetation coverage. The results indicate that nearly 98% of the total NOy deposition (dry and wet deposition of NO, NO2, HNO3, and NO3) in Tehran's urban and suburban area is attributed to dry deposition of NO2.

First Results of Nb3Sn Coated Cavity by Vapor Diffusion Method at SARI

Nb3Sn is emerging as one of the focal points in superconducting radio frequency (SRF) research, owing to its excellent superconducting properties. These properties hold significant possibilities for cost reduction and the miniaturization of accelerators. In this paper, we report the recent efforts of the Shanghai Advanced Research Institute (SARI) in fabricating high-performance Nb3Sn superconducting cavities using the vapor diffusion method. This includes the construction of a Nb3Sn coating system with dual evaporators and the test results of 1.3 GHz single-cell coated cavities. The coated samples were characterized, and the growth state of the Nb3Sn films was analyzed. The first coated superconducting cavity was tested at both 4.4 K and 2 K, with different cooldown rates passing through the Nb3Sn critical temperatures. The causes of Sn droplet spot defect formation on the surface of the first cavity were analyzed, and such defects were eliminated in the coating of the second cavity by controlling the evaporation rate. This study provides a reference for the preparation of high-performance Nb3Sn-coated cavities using the vapor diffusion method, including the setup of the coating system, the comprehension of the vapor diffusion process, and the test conditions.

Synergistic effects of nonionic surfactants ethoxylated alkylamines and sodium dodecyl sulfate in mixed systems

HypothesisIn general, the performance of surfactant hybrid systems is better than that of single surfactants, so surfactant hybrid systems are widely used in various industries. As a very important class of nonionic surfactants, ethoxylated alkylamines have been widely used in industries such as washing, coating, and pesticide, but little research has been conducted on their mixed systems. In order to improve the utilization efficiency of surfactants and reduce wastage, the surface properties and aggregation behavior of ethoxylated alkylamine mixed systems should be further explored. ExperimentIn this study, the nonionic surfactant ethoxylated dodecylamine (AC-1202) and the anionic surfactant sodium dodecyl sulfate (SDS) were used to form a mixed system. The static surface tension and interaction parameters of the mixed system under the influence of inorganic salt ions were investigated using a KRÜSS K12 surface tensiometer. The diffusion process of the mixed system was investigated using a KRÜSS bubble pressure tensiometer. At the same time, the aggregate behavior of the mixed system was studied by particle size analyzer. In addition, the contact angle and rheological properties of the mixed solution were also investigated. FindingsThe SDS/AC-1202 mixture system formed a synergistic effect that could reduce the CMC value to 24.20 mN/m and the CMC value was as low as 22.89 mN/m after the addition of inorganic salts. The mixed system conforms to the kinetic mechanism of mixing and diffusion and the Ostwald de model for non-Newtonian fluids. Finally, there is a good aggregation pattern in the mixed system, and the stronger synergistic effect will lead to the reduction of the average particle size of the mixture to 45.41 nm.

Exploring Impact of Various Operating Parameters on the Specific Capacitance at the Glassy Carbon/H2SO4 Interface: A Comparative Analysis Using Electrochemical Characterization

AbstractThe aim of this study is to investigate the influence of scanning rate, electrolyte concentration, temperature and electrode rotation speed on the capacitance of glassy carbon electrode in sulfuric acid solution using cyclic voltammetry (CV). The results show that they have a significant influence on the capacitance with varying experimental conditions. In addition, the electrochemical impedance spectroscopy (EIS) method was employed to conduct a more thorough analysis of the ways in which hydrodynamic circumstances resulting from a rotating electrode affect the electrode capacity and the charge storage process. Step potential electrochemical spectroscopy (SPECS) was used to identify the various charge storage mechanisms involved. It was shown that the voltammograms measured by the CV method and determined from the SPECS method have a quasi‐rectangular shape, revealing a predominantly capacitive behavior and that capacitance decreases with increasing scanning rate. Furthermore, both methods confirm that the contribution of the diffusion process is the main factor influencing the charge storage mechanism when the sweep rate is taken into account. However, the SPECS approach provides more accurate and detailed information regarding the kinetic characteristics of the electrode.

Strategic grain boundary diffusion process for high-performance Ce-containing sintered Nd-Fe-B magnets

Sintered Nd-Fe-B magnets are an important driver of green technology, and the grain boundary diffusion process (GBDP) has become the most economically efficient method to improve the overall magnetic properties of sintered Nd-Fe-B magnets. In the work, to further reduce the utilization cost of sintered Nd-Fe-B permanent magnets with high performance, the strategic GBDP was explored based on the demagnetization characteristics of Nd-Fe-B permanent magnet materials in motors. The peculiar fact about the process was that the diffusion source was deposited on a part of the c-plane, that is, the strategic selected area grain boundary diffusion process (S-SAGBDP). With the objective of addressing the edge demagnetization, the diffusion source was initially deposited only at the edges of the c-plane. Despite the overall magnetic properties and temperature coefficients of the diffused magnet were significantly enhanced, the serious deteriorations of squareness and surface magnetic field were particularly worrying. Consequently, the central area of the magnet was simultaneously strengthened. The squareness and demagnetization property of the magnet after S-SAGBDP were greatly improved, and the amount of heavy rare earths was reduced by 25%. The above work clearly illustrates the practical value of S-SAGBDP, which is helpful to develop the cost-effective and commercial-grade sintered Nd-Fe-B magnets.

Deep Neural Networks with Spacetime RBF for Solving Forward and Inverse Problems in the Diffusion Process

This study introduces a deep neural network approach that utilizes radial basis functions (RBFs) to solve forward and inverse problems in the process of diffusion. The input layer incorporates multiquadric (MQ) RBFs, symbolizing the radial distance between the boundary points on the spacetime boundary and the source points positioned outside the spacetime boundary. The output layer is the initial and boundary data given by analytical solutions of the diffusion equation. Utilizing the concept of the spacetime coordinates, the approximations for forward and backward diffusion problems involve assigning initial data on the bottom or top spacetime boundaries, respectively. As the need for discretization of the governing equation is eliminated, our straightforward approach uses only the provided boundary data and MQ RBFs. To validate the proposed method, various diffusion scenarios, including forward, backward, and inverse problems with noise, are examined. Results indicate that the method can achieve high-precision numerical solutions for solving diffusion problems. Notably, only 1/4 of the initial and boundary conditions are known, yet the method still yields precise results.

Polymer Crystallization Kinetics and Thermodynamics of Some Industrial Polyamides

A comprehensive non-isothermal kinetics study on polymer crystallization processes taking place in a set of industrial polyamides comprising nylon 6, nylon 6,6, nylon 11 and nylon 12, individually, is reported. The kinetics studies elucidated that the phenomena of nucleation/diffusion underlying the nylons crystallization go to completion in a single-step. Notwithstanding, the nylons diffusion activation energies do not correspond to the universal value of segmental jump activation energy signifying polymer chains diffusion processes. The polymer chain transport phenomenon was probably the slowest one in the case of nylon 6 and nylon 6,6, and the fastest in the case of nylon 12, while intermediate for nylon 11. Furthermore, the nucleation barrier during the course of polymer crystallization was the highest for nylon 6,6, followed by nylon 6, nylon 11 and nylon 12. Our kinetics studies further predict that the crystallization of nylon 12 and nylon 11 follows, respectively, diffusion-controlled 2D growth of spherulites and a somewhat complicated nucleation/growth phenomenon. The thermodynamics of the nylons crystallization suggests that the highest structural orientation of the activated complex was attained in the case of the nylon 12 crystallization process. Interestingly, while the thermodynamics and majority of the kinetic parameters of nylon 6 and nylon 6,6 were similar/comparable, the two follow widely differing crystallization mechanisms. The most probable physical meanings of the obtained kinetics and thermodynamics parameters and their practical significance are given and discussed.