The shift in the percolation threshold of compressed composites was studied by a 3D continuum percolation model. A Monte Carlo (MC) method was employed in the simulations. The percolation threshold was found to rise w...The shift in the percolation threshold of compressed composites was studied by a 3D continuum percolation model. A Monte Carlo (MC) method was employed in the simulations. The percolation threshold was found to rise with the compression strain, which captures the basic trend in compression-induced conductivity variation from the experiments. Both fiber bending and texture formation contribute to the percolation threshold. The results suggest that fillers with a high aspect ratio are more desirable for sensor and electrical switch applications.展开更多
In recent years, the threats posed by computer viruses have become increasingly diverse and complex. While classic percolation theory provides a novel perspective for analyzing epidemics and information dissemination,...In recent years, the threats posed by computer viruses have become increasingly diverse and complex. While classic percolation theory provides a novel perspective for analyzing epidemics and information dissemination, it fails to capture the temporal dynamics of these systems and the effects of virus invasion and governmental regulation. Triadic percolation theory, a recent advancement, addresses these limitations. In this paper, we apply this new percolation mechanism to model the diffusion of computer viruses, deriving a precise mathematical formulation of the triadic percolation model and providing an analytical solution of the triadic percolation threshold. Additionally, we investigate the impact of nonlinear transmission probability characteristics on virus propagation. Numerical simulations demonstrate that reducing the network's average degree(or the positive regulation) or increasing regulatory interventions raises the outbreak threshold for computer viruses while decreasing their final size. Moreover, the study reveals that nonlinear transmission probabilities result in an increased number of solutions for the final size of the computer viruses. Our findings contribute new insights into controlling the spread of computer viruses.展开更多
Different aspect ratio silver nano-structured materials including nanocubes,nanorods and nanowires were prepared by micro-waved assisted glycol reduction method.Different characterization methods including SEM and XRD...Different aspect ratio silver nano-structured materials including nanocubes,nanorods and nanowires were prepared by micro-waved assisted glycol reduction method.Different characterization methods including SEM and XRD were processed on these nanomaterials.Isotropical conductive adhesives(ICA) were developed by using these Ag nanomaterials as conductive fillers.It was found that the conductivity and thermal conductivity percolation threshold of the ICA depended on the morphologies of the fillers,lower percolation threshold could be obtained by using higher aspect ratio filler.A modified percolation threshold theory was put forward to explain and simulate the experiment results,the simulated results could match the experiment results very well.展开更多
The percolation threshold(PT)for colloidal system refers to the point at which particles aggregate to form an infinite cluster that spans the suspension[1].It is widely assumed that the percolation transition should f...The percolation threshold(PT)for colloidal system refers to the point at which particles aggregate to form an infinite cluster that spans the suspension[1].It is widely assumed that the percolation transition should follow the concept of scaling,and recent numerical studies[2-5]have shown that the wrapping probability of percolation can be described by the universal scaling functions,which enables the estimation of PTs for different types of system.展开更多
This paper presents the results of an experimental study of the percolation behavior of the complex dielectric constant of ceramic matrix composites(CMC).Samples of piezoactive CMC were obtained by joint sintering of ...This paper presents the results of an experimental study of the percolation behavior of the complex dielectric constant of ceramic matrix composites(CMC).Samples of piezoactive CMC were obtained by joint sintering of synthesized PZT piezoceramic powder(matrix)and crushed particles of sintered PZT piezoceramics(filler)of different compositions.The experimental dependencies of real and imaginary parts of the complex dielectric constant of CMC on the porosity of piezoceramic matrix and volume content of ceramic filler particles were measured and analyzed.It was shown that the additional porosity of the ceramic matrix resulting from sintering of the CMC masks the dielectric percolation transition,that actually occurs at the volume concentration of ceramic filler close to percolation threshold(V~1/3).展开更多
The relationship between the thermal/electrical conductivity enhancement in graphite nanoplatelets （GNPs） composites and the properties of filling graphite nanoplatelets is studied. The effective thermal and electri...The relationship between the thermal/electrical conductivity enhancement in graphite nanoplatelets （GNPs） composites and the properties of filling graphite nanoplatelets is studied. The effective thermal and electrical conductivity enhancements of GNP-oil nanofluids and GNP-polyimide composites are measured. By taking into account the particle shape, the volume fraction, the thermal conductivity of filling particles and the base fluids, the thermal and electrical conductivity enhancements of GNP nanofluids are theoretically predicted by the generalized effective medium theory. Both the nonlinear dependence of effective thermal conductivity on the GNP volume fraction in nanofhiids and the very low percolation threshold for GNP-polyimide composites are well predicted. The theoretical predications are found to be in reasonably good agreement with the experimental data. The generalized effective medium theory can be used for predicting the thermal and electrical properties of GNP composites and it is still available for most of the thermal/electrical modifications in two-phase composites.展开更多
The flexible transparent conductive films （FrCFs） of silver nanowire-polyethylene terephthalate （AgNW- PET） were prepared by a facile method including vacuum filtration and mold transferring. The effect of silver ...The flexible transparent conductive films （FrCFs） of silver nanowire-polyethylene terephthalate （AgNW- PET） were prepared by a facile method including vacuum filtration and mold transferring. The effect of silver nanowire weight density on the optical and electrical properties of films, as well as the electrical percolation was investigated. The obtained typical AgNW-PET film exhibited high figure of merit of 31.3 × 10^-3 Ω^-1 with low sheet resistance of 4.95 D sq^-1 and high transparency at 550 nm of 83.0% （excluding PET substrate）. The resulting FTCFs based on PET substrate with high transmittance and low sheet resistance have a great potential in the application of high-performance flexible electronics and photovoltaic devices.展开更多
A novel capacitance-type relative humidity(RH) sensor based on multi-wall carbon nanotube/SiO(MWCNTs/SiO) composite film is reported.Details of the fabrication process,possible sensing mechanism and sensing characteri...A novel capacitance-type relative humidity(RH) sensor based on multi-wall carbon nanotube/SiO(MWCNTs/SiO) composite film is reported.Details of the fabrication process,possible sensing mechanism and sensing characteristics,such as linearity and sensitivity,are described.The capacitance of the MWCNTs/SiOcomposite film shows typical concentration percolation behavior with increasing MWCNT loading.At loadings below the percolation threshold(1.842wt%),the sensor capacitance increases obviously with increasing MWCNTs. The water condensed in the MWCNTs/SiOlayer can lower the percolation threshold and increase the sensor capacitance.The sensor with MWCNT concentration of 1wt%has the best properties.The sensor has a humidity sensitivity of about 673 pF/%RH and a linearity correlation of 0.98428.The response time of the sensor to RH is about 40 s and the recovery time is about 2 s.展开更多
Swellable matrix represents one of the most employed controlled release systems. These dosage forms provide slow release of drugs to reduce the fluctuation of drug concentration in plasma in order to improve the effic...Swellable matrix represents one of the most employed controlled release systems. These dosage forms provide slow release of drugs to reduce the fluctuation of drug concentration in plasma in order to improve the efficiency of treatment and/or to reduce adverse effects. The application of the concepts of statistical physics has allowed discovering the existence of critical points in the formulation of swellable matrices. These points, representing the volume fractions of the tablet components where the properties of the matrix diverge or change suddenly, provide important knowledge of how to rationalize the design of swellable matrices. The critical points are generally related to the percolation threshold of one of the components of the formulation, which corresponds to a geometrical phase transition of this component, passing from isolation to spanning the whole system. The last section of the paper is devoted to more recent findings concerning the influence of particle size of the components on the percolation threshold of the matrix forming polymer, and therefore on the release behaviour of the matrix. Knowledge of the excipient percolation threshold allows a more rational design of swellable matrices, according to the guidelines of the regulatory authorities concerning science-based formulation and quality by design.展开更多
Modification of carbon nanotubes (CNTs) and their incoporation in polymer matrix have attracted much attention of researchers. As maximum dispersion of CNTs could enhance the properties of matrix dynamically, research...Modification of carbon nanotubes (CNTs) and their incoporation in polymer matrix have attracted much attention of researchers. As maximum dispersion of CNTs could enhance the properties of matrix dynamically, researchers are trying to find new methodologies to obtain this target. However, maximum dispersion remains a great challenge and under the stage of progress. Here, we claimed the synthesis of composites with a highly uniform dispersion of the filler that results significantly improved electrical features. In this regard, composites of polymethylmethacrylate (PMMA) were fabricated by using pristine and zwitterionic surfactant (ZIS) modified CNTs (ZIS-CNTs). Characterization was done by using ultraviolet-visible (UV-Vis), Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermo gravimetric analysis (TGA) techniques. UV-Vis and FTIR spectroscopy confirmed the synthesis of ZIS-CNTs and composites. UV-Vis spectra showed an increase in wavelength with the decrease in optical band gap for CNTs-based (CNTs/PMMA) and ZIS-CNTs-based (ZIS-CNTs/PMMA) composites. SEM and XRD studies confirmed a significant homogenoeus and uniform dispersion of CNTs in ZIS- CNTs/PMMA composites. An increase in conductivity of PMMA from 10^(−9) to 10^(−2) and 10^(−1) S/cm was observed on addition of less than 1% (mass fraction) of CNTs without and with modification by ZIS, respectively. Low values of percolation threshold at 0.5% and 0.005% for CNTs/PMMA and ZIS- CNTs/PMMA composites were obtained, respectively. TGA analysis showed a slow rate of decomposition for composites than that for pure PMMA. Around 600 ℃, 3% CNTs/PMMA and 7% ZIS-CNTs/PMMA composites were left in the end, which depicts the increase in thermal stability of PMMA. This work depicts a better dispersion of CNTs in PMMA matrix via slight modification in synthesis as well as by using ZIS as surfactant.展开更多
基金Project supported by the National Natural Science Foundation of China (No 10832009)the National Basic Research Program (973) of China (No 2004CB619304)the Science Foundation of Chinese University (No 2009QNA4034)
文摘The shift in the percolation threshold of compressed composites was studied by a 3D continuum percolation model. A Monte Carlo (MC) method was employed in the simulations. The percolation threshold was found to rise with the compression strain, which captures the basic trend in compression-induced conductivity variation from the experiments. Both fiber bending and texture formation contribute to the percolation threshold. The results suggest that fillers with a high aspect ratio are more desirable for sensor and electrical switch applications.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12101573 and 12022113)the Fundamental Research Program of Shanxi Province,China (Grant Nos. 20210302124381,202203021211213,and 20210302123018)。
文摘In recent years, the threats posed by computer viruses have become increasingly diverse and complex. While classic percolation theory provides a novel perspective for analyzing epidemics and information dissemination, it fails to capture the temporal dynamics of these systems and the effects of virus invasion and governmental regulation. Triadic percolation theory, a recent advancement, addresses these limitations. In this paper, we apply this new percolation mechanism to model the diffusion of computer viruses, deriving a precise mathematical formulation of the triadic percolation model and providing an analytical solution of the triadic percolation threshold. Additionally, we investigate the impact of nonlinear transmission probability characteristics on virus propagation. Numerical simulations demonstrate that reducing the network's average degree(or the positive regulation) or increasing regulatory interventions raises the outbreak threshold for computer viruses while decreasing their final size. Moreover, the study reveals that nonlinear transmission probabilities result in an increased number of solutions for the final size of the computer viruses. Our findings contribute new insights into controlling the spread of computer viruses.
文摘Different aspect ratio silver nano-structured materials including nanocubes,nanorods and nanowires were prepared by micro-waved assisted glycol reduction method.Different characterization methods including SEM and XRD were processed on these nanomaterials.Isotropical conductive adhesives(ICA) were developed by using these Ag nanomaterials as conductive fillers.It was found that the conductivity and thermal conductivity percolation threshold of the ICA depended on the morphologies of the fillers,lower percolation threshold could be obtained by using higher aspect ratio filler.A modified percolation threshold theory was put forward to explain and simulate the experiment results,the simulated results could match the experiment results very well.
基金supported by the National Natural Science Foundation of China(Grant Nos. 11602279,11232013,and 11472285)
文摘The percolation threshold(PT)for colloidal system refers to the point at which particles aggregate to form an infinite cluster that spans the suspension[1].It is widely assumed that the percolation transition should follow the concept of scaling,and recent numerical studies[2-5]have shown that the wrapping probability of percolation can be described by the universal scaling functions,which enables the estimation of PTs for different types of system.
基金supported by the Russian Science Foundation Grant No.24-22-00063。
文摘This paper presents the results of an experimental study of the percolation behavior of the complex dielectric constant of ceramic matrix composites(CMC).Samples of piezoactive CMC were obtained by joint sintering of synthesized PZT piezoceramic powder(matrix)and crushed particles of sintered PZT piezoceramics(filler)of different compositions.The experimental dependencies of real and imaginary parts of the complex dielectric constant of CMC on the porosity of piezoceramic matrix and volume content of ceramic filler particles were measured and analyzed.It was shown that the additional porosity of the ceramic matrix resulting from sintering of the CMC masks the dielectric percolation transition,that actually occurs at the volume concentration of ceramic filler close to percolation threshold(V~1/3).
基金The National Natural Science Foundation of China(No.50906073,31070517)China Postdoctoral Science Foundation(No.20110491332)+1 种基金Jiangsu Planned Projects for Postdoctoral Research Funds(No.1101009B)the Science and Technology Development Plan of North Jiangsu(No.BC2012444)
文摘The relationship between the thermal/electrical conductivity enhancement in graphite nanoplatelets （GNPs） composites and the properties of filling graphite nanoplatelets is studied. The effective thermal and electrical conductivity enhancements of GNP-oil nanofluids and GNP-polyimide composites are measured. By taking into account the particle shape, the volume fraction, the thermal conductivity of filling particles and the base fluids, the thermal and electrical conductivity enhancements of GNP nanofluids are theoretically predicted by the generalized effective medium theory. Both the nonlinear dependence of effective thermal conductivity on the GNP volume fraction in nanofhiids and the very low percolation threshold for GNP-polyimide composites are well predicted. The theoretical predications are found to be in reasonably good agreement with the experimental data. The generalized effective medium theory can be used for predicting the thermal and electrical properties of GNP composites and it is still available for most of the thermal/electrical modifications in two-phase composites.
基金financial support from the National Natural Science Foundation of China(Grant No.21203226)Ningbo Key Laboratory of Silicon and Organic Thin Film Optoelectronic Technologies(Grant No.2014A22002)
文摘The flexible transparent conductive films （FrCFs） of silver nanowire-polyethylene terephthalate （AgNW- PET） were prepared by a facile method including vacuum filtration and mold transferring. The effect of silver nanowire weight density on the optical and electrical properties of films, as well as the electrical percolation was investigated. The obtained typical AgNW-PET film exhibited high figure of merit of 31.3 × 10^-3 Ω^-1 with low sheet resistance of 4.95 D sq^-1 and high transparency at 550 nm of 83.0% （excluding PET substrate）. The resulting FTCFs based on PET substrate with high transmittance and low sheet resistance have a great potential in the application of high-performance flexible electronics and photovoltaic devices.
文摘A novel capacitance-type relative humidity(RH) sensor based on multi-wall carbon nanotube/SiO(MWCNTs/SiO) composite film is reported.Details of the fabrication process,possible sensing mechanism and sensing characteristics,such as linearity and sensitivity,are described.The capacitance of the MWCNTs/SiOcomposite film shows typical concentration percolation behavior with increasing MWCNT loading.At loadings below the percolation threshold(1.842wt%),the sensor capacitance increases obviously with increasing MWCNTs. The water condensed in the MWCNTs/SiOlayer can lower the percolation threshold and increase the sensor capacitance.The sensor with MWCNT concentration of 1wt%has the best properties.The sensor has a humidity sensitivity of about 673 pF/%RH and a linearity correlation of 0.98428.The response time of the sensor to RH is about 40 s and the recovery time is about 2 s.
文摘Swellable matrix represents one of the most employed controlled release systems. These dosage forms provide slow release of drugs to reduce the fluctuation of drug concentration in plasma in order to improve the efficiency of treatment and/or to reduce adverse effects. The application of the concepts of statistical physics has allowed discovering the existence of critical points in the formulation of swellable matrices. These points, representing the volume fractions of the tablet components where the properties of the matrix diverge or change suddenly, provide important knowledge of how to rationalize the design of swellable matrices. The critical points are generally related to the percolation threshold of one of the components of the formulation, which corresponds to a geometrical phase transition of this component, passing from isolation to spanning the whole system. The last section of the paper is devoted to more recent findings concerning the influence of particle size of the components on the percolation threshold of the matrix forming polymer, and therefore on the release behaviour of the matrix. Knowledge of the excipient percolation threshold allows a more rational design of swellable matrices, according to the guidelines of the regulatory authorities concerning science-based formulation and quality by design.
基金the University of Punjab,Lahore,for financial support to carry out this research work through a research project(PU Research Grant 2017-18).
文摘Modification of carbon nanotubes (CNTs) and their incoporation in polymer matrix have attracted much attention of researchers. As maximum dispersion of CNTs could enhance the properties of matrix dynamically, researchers are trying to find new methodologies to obtain this target. However, maximum dispersion remains a great challenge and under the stage of progress. Here, we claimed the synthesis of composites with a highly uniform dispersion of the filler that results significantly improved electrical features. In this regard, composites of polymethylmethacrylate (PMMA) were fabricated by using pristine and zwitterionic surfactant (ZIS) modified CNTs (ZIS-CNTs). Characterization was done by using ultraviolet-visible (UV-Vis), Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermo gravimetric analysis (TGA) techniques. UV-Vis and FTIR spectroscopy confirmed the synthesis of ZIS-CNTs and composites. UV-Vis spectra showed an increase in wavelength with the decrease in optical band gap for CNTs-based (CNTs/PMMA) and ZIS-CNTs-based (ZIS-CNTs/PMMA) composites. SEM and XRD studies confirmed a significant homogenoeus and uniform dispersion of CNTs in ZIS- CNTs/PMMA composites. An increase in conductivity of PMMA from 10^(−9) to 10^(−2) and 10^(−1) S/cm was observed on addition of less than 1% (mass fraction) of CNTs without and with modification by ZIS, respectively. Low values of percolation threshold at 0.5% and 0.005% for CNTs/PMMA and ZIS- CNTs/PMMA composites were obtained, respectively. TGA analysis showed a slow rate of decomposition for composites than that for pure PMMA. Around 600 ℃, 3% CNTs/PMMA and 7% ZIS-CNTs/PMMA composites were left in the end, which depicts the increase in thermal stability of PMMA. This work depicts a better dispersion of CNTs in PMMA matrix via slight modification in synthesis as well as by using ZIS as surfactant.
