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In this work, we aim to investigate and compare the combustion reactivities of real biofuel soot and fossil-fuel soot in the active and passive regeneration conditions of DPF and GPF through temperature-programmed oxidation (TPO). Higher reactivity of biofuel soot is achieved even under GPF conditions with extremely low oxygen concentration (~ 1%), which provides a great potential for low-temperature regeneration of GPF. Such a result is mainly attributed to the low graphitization and less surface C = C groups of biofuel soot. Unfortunately, the presence of high-content ashes (~ 47%) and P impurity in real biofuel soot hinder its combustion reactivity. TPO evidences that the O2/NOX-lacking conditions in GPF are key factors to impact the combustion of soot, especially fossil-fuel soot. This work provides some useful information for understanding real biofuel and fossil-fuel soot combustion in GPF and DPF regeneration and further improvement in filter regeneration process. [ABSTRACT FROM AUTHOR]

The cell structure of a gasoline particulate filter (GPF) is made up of thousands of individual cells. Although the symmetric square cell structure of the GPF is commonly used internationally, several cell designs have been proposed to reduce the pressure drop in the GPF trapping process. The aim of this paper was to use AVL-Fire software to establish GPF models of different cell structures, mainly including the symmetric square cell structure, asymmetric square cell structure, and symmetric hexagonal cell structure, and analyze the GPF pressure drop characteristics of different cell structures according to the carrier structural parameters and altitude. The results show that compared with the pressure drop of the symmetric square cell structure, the pressure drop of the asymmetric cell structure with inlet/outlet side length ratios ranging from 1.1 to 1.4 is decreased by 4.61%, 9.07%, 12.19%, and 13.22%, respectively, and the pressure drop of the symmetric hexagonal cell structure is decreased by 33.17%. Both asymmetric and symmetric hexagonal cell structure GPFs can decrease the pressure drop during trapping by increasing the cell density. From 200 CPSI to 300 CPSI, the pressure drop of the asymmetric cell structure with inlet/outlet side length ratios ranging from 1.1 to 1.4 is decreased by 20.43%, 20.53%, 20.39%, and 18.56%, respectively, and the pressure drop of the symmetric hexagonal cell structure is decreased by 18.70%. The pressure drop values of GPFs with asymmetric and symmetric hexagonal cell structures show an increasing trend with an increasing filter wall thickness and inlet/outlet plug length. The pressure drop values of GPFs with asymmetric and symmetric hexagonal cell structures show an increasing trend with an increasing altitude, and the larger the inlet/outlet ratio, the more significant the increase in the pressure drop. [ABSTRACT FROM AUTHOR]

The cell structure of a gasoline particulate filter (GPF) is made up of thousands of individual cells. Although the symmetric square cell structure of the GPF is commonly used internationally, several cell designs have been proposed to reduce the pressure drop in the GPF trapping process. The aim of this paper was to use AVL-Fire software to establish GPF models of different cell structures, mainly including the symmetric square cell structure, asymmetric square cell structure, and symmetric hexagonal cell structure, and analyze the GPF pressure drop characteristics of different cell structures according to the carrier structural parameters and altitude. The results show that compared with the pressure drop of the symmetric square cell structure, the pressure drop of the asymmetric cell structure with inlet/outlet side length ratios ranging from 1.1 to 1.4 is decreased by 4.61%, 9.07%, 12.19%, and 13.22%, respectively, and the pressure drop of the symmetric hexagonal cell structure is decreased by 33.17%. Both asymmetric and symmetric hexagonal cell structure GPFs can decrease the pressure drop during trapping by increasing the cell density. From 200 CPSI to 300 CPSI, the pressure drop of the asymmetric cell structure with inlet/outlet side length ratios ranging from 1.1 to 1.4 is decreased by 20.43%, 20.53%, 20.39%, and 18.56%, respectively, and the pressure drop of the symmetric hexagonal cell structure is decreased by 18.70%. The pressure drop values of GPFs with asymmetric and symmetric hexagonal cell structures show an increasing trend with an increasing filter wall thickness and inlet/outlet plug length. The pressure drop values of GPFs with asymmetric and symmetric hexagonal cell structures show an increasing trend with an increasing altitude, and the larger the inlet/outlet ratio, the more significant the increase in the pressure drop.

To reduce the emission of fine particulate matter (PM) from gasoline engines, a gasoline particulate filter (GPF) filtration model that considers the fractal characteristics of both particulate matter and filters is designed and its filtration characteristics are analyzed based on several GPF filtration models. Based on the GPF filtration mechanism, a new mathematical model of fiber efficiency filtration is established after correcting the classical filtration formula based on correcting the particle size of particles and considering the relationship between the porosity of the fiber filter and the fractal dimension of the filter. Simulation of the filtration efficiency of the established mathematical filtration model is carried out to obtain visual filtration efficiency curves. The filtration efficiency and pressure drop of the model are analyzed, and the effects of parameters such as particle fractal dimension, filter fractal dimension, filter thickness, flow rate, and fiber diameter on filtration efficiency are also comprehensively analyzed. The results show that when the fractal dimension of particles is in the range of 1.8-2.8, the most penetrating particle size decreases with the increase of the fractal dimension of particles. When the particle size is small, the effect of fractal dimension on filtration efficiency is not obvious. When the particle size is larger than the most penetrating particle range, the larger the fractal dimension, the filtration efficiency increases obviously. Considering the relationship between the fractal dimension of the filter body and the porosity and the influence of each on the filtration efficiency, the optimal fractal dimension of the filter body should be between 1.82 and 1.925, and the thickness of the filter has some influence on the filtration efficiency. The slower the gas flow rate is, the better the trapping effect will be. However, considering the problem of automobile emission, a lower exhaust speed can be chosen. Increasing the fiber diameter can improve the trapping efficiency of the model, but will reduce the porosity of the trapping collective. Therefore, the fiber diameter should not be too large under the combined action.

Fractal theory was used to characterize particles and particle trapping parameters to accurately predict the particle filtration process inside a gasoline engine particle filter (GPF). The particles were fractal aggregates, and the fractal dimension (Df) was introduced to redefine the particle size. The porous medium inside the particle filter was a solid phase fractal. The pore tortuosity fractal dimension (Dt) and the pore area fractal dimension (Da) were introduced to define the fiber length of the trap. The Brownian diffusion coefficient and permeability were modified. A new fractal numerical model of GPF filtration efficiency was proposed based on the classical filtration theory. The results show that the fractal expansion model of filtration efficiency has good applicability. The influence of GPF structural parameters on filtration efficiency and pressure drop was analyzed. In this study, two performance metrics, trapping efficiency and pressure drop, were considered by fractal expansion filtration modeling. It is possible to increase or decrease filtration efficiency by adjusting the porosity and pore diameter. [ABSTRACT FROM AUTHOR]

Modern and contemporary technological developments have been the need of the hour in the present time. Extensive research showed that there has been significant enhancements in technologies that work on improving network paradigms like FANET and VANET creating evolutionary ideas. Latest studies have shown that, the research is budding in multi-drone communications with the swarm of UAVs called flying adhoc network (FANET). Not only are FANETs more reliable than single UAV but are also likely to be more efficacious and advantageous in finishing operational tasks. Interestingly, due to the high mobility characteristic, FANETs don't have a fixed topology and expeditiously changes its topological structure which makes coordination between UAVs in the FANET arduous. The UAVs deployed for real time applications possess myriad of features such as on-board video streaming, streaming and more. The on-board systems on the UAVs utilise the protocol with high bandwidth, mobility, link stability and high energy consumption. However, the extant solutions used in the conventional adhoc network for node coordination cannot be applied in the FANET. Hence, this paper addresses the above mentioned issues by proposing a novel distributed node coordination algorithm for FANETs. The crux in this proposed algorithm is to make use of the General Potential Field based node coordination (GPFnc). The next stage involves validating the experimental results by developing two simulated environments—dynamic and static respectively in which , the performance metrics—feasibility and effectiveness of FANET were measured and analysed. The results of the experiment clearly demonstrated that the proposed GPFnc achieves enhanced scalability, reliability and fast network formation than the existing contemporary algorithms of MANET. Finally, the proposed GPFnc achieves a maximum of 63% reliable throughput with extremely low jitter and the latency is computed to be is 1.5 × times better than the present state-of-art algorithms. [ABSTRACT FROM AUTHOR]

Particles larger than 10 nm from engine exhaust are gaining global concerns. In light of this, to investigate how EGR affects gasoline vehicle SPN10 (solid particles larger than 10 nm) emissions, seven gasoline vehicles (hybrid or conventional) were studied experimentally. The results revealed that EGR vehicles risk failing the current limit (6 * 1011 #/km) more than those without EGR if the cut-off size was tightened from 23 nm to 10 nm. More specifically, during the WLTC test, EGR increased the SPN10 emission factors by 2 ∼ 3 times depending on vehicle powertrains (conventional or hybrid). Notably, SPN10 emissions increased significantly when EGR was actively engaged but showed a decrease when the EGR rate remained constant. EGR and the enriched fuel–air mixture are the critical reasons for the increased SPN10.

The European Union Fit For 55 program plans to cease the production and sales of vehicles with the internal combustion engines in 2035, although fuel powered vehicles will remain on the road for many more years to come.The micro-contaminants (MC) in gasoline exhaust such as Polycyclic Aromatic Hydrocarbons (PAHs) and their derivatives, ions, metals and metalloids are highly toxic and carcinogenic.The gasoline particulate filter (GPF) is the most commonly used solution for solid particulate emission control. Studies show that use of the metals such as Cu, Co, Fe, Ni or Mn improves oxidation of MCs. The aim of this study is to review the knowledge about the gasoline particulate filters, their mechanisms of pollutants removal and to highlight the probable insufficiency in avoiding of hazardous micro-contaminants emission. The work also reviews some more important and relevant publications to the subject.

In this research, RDE tests were carried out on a pre-China 6 TGDI vehicle in the two cases of installing or not installing GPF to explore the impacts of GPF on RDE emission behaviors. The results indicated that the GPF can effectively filter PN emissions, especially at low speed, high load engine operating conditions, where the PN emissions can be reduced to about 1/200 of the original emissions. For TGDI vehicles, the installation of GPF can reduce the RDE PN emissions by more than 30 times, which indicates that the GPF is the key post-processing device for TGDI vehicles to meet the China 6 regulation. And in the upgrade process of China 5 vehicles to China 6 vehicles, especially for TGDI vehicles, the engine, the post processor and the turbocharger all needs re-calibrating or re-matching to concur a series of problems the back pressure raise caused by the installation of GPF, which may bring deterioration of engine combustion process, decrease of catalyst temperature and similar conditions that will worsen the vehicle emissions.

Fractal theory was used to characterize particles and particle trapping parameters to accurately predict the particle filtration process inside a gasoline engine particle filter (GPF). The particles were fractal aggregates, and the fractal dimension (Df) was introduced to redefine the particle size. The porous medium inside the particle filter was a solid phase fractal. The pore tortuosity fractal dimension (Dt) and the pore area fractal dimension (Da) were introduced to define the fiber length of the trap. The Brownian diffusion coefficient and permeability were modified. A new fractal numerical model of GPF filtration efficiency was proposed based on the classical filtration theory. The results show that the fractal expansion model of filtration efficiency has good applicability. The influence of GPF structural parameters on filtration efficiency and pressure drop was analyzed. In this study, two performance metrics, trapping efficiency and pressure drop, were considered by fractal expansion filtration modeling. It is possible to increase or decrease filtration efficiency by adjusting the porosity and pore diameter.

New EU7 emission standards are currently under development. While the timing and exact level of stringency of these standards is not available, both OEMs and suppliers are preparing to meet significantly reduced tailpipe NOx and particle number standards for both light- and heavy-duty vehicles. We present here some of the emission control systems that are likely to be implemented and details on the advanced component technologies.

Gasoline engines, mainly gasoline direct injection engines (GDI) require, in addition to three-way catalysts (TWC), a new catalytic system to remove the formed soot. Gasoline Particle Filters (GPF) are, among others, a possible solution. BaMnO3 and copper-doped BaMnO3 perovskites seem to be a feasible alternative to current catalysts for GPF. The physical and chemical properties of these two perovskites determining the catalytic performance have been modified using different synthesis routes: (i) sol-gel, (ii) modified sol-gel and iii) hydrothermal. The deep characterization allows concluding that: (i) all samples present a perovskite-like structure (hexagonal), except BMC3 which shows a polytype one (due to the distortion caused by copper insertion in the lattice), and ii) when a low calcination temperature is used during synthesis, the sintering effect decreases and the textural properties, the reducibility and the oxygen mobility are improved. The study of soot oxidation simulating the hardest GDI scenarios reveals that, as for diesel soot removal, the best catalytic performance involves the presence of oxygen vacancies to adsorb and activate oxygen and a labile Mn (IV)/Mn (III) redox pair to dissociate the adsorbed oxygen. The combination of both properties allows the transport of the dissociated oxygen towards the soot. [ABSTRACT FROM AUTHOR]

The article presents emission test results comparison carried out on a dynamic engine dynamometer. Parameters were recorded during a drive made in accordance with the requirements of the RDE. Test bench allowed to determine the particle mass and number emission in the repetitive engine operation conditions. One of three used elements wan an OEM solution from one of particulate filters producers, the other was intended for use in original systems, the third was a custom product. The highest efficiency of particulate filtration was demonstrated by the last filter, which was adapted to the engine. [ABSTRACT FROM AUTHOR]

The current EURO 6c standard has introduced a limit on the number of solid particles for spark ignition engines equal to that for compression ignition engines (6x10e11). To meet the requirements, manufacturers install particulate filters in the exhaust systems of most new engines. The article presents the results of vehicle testing with this solution during the drive carried out in accordance with the RDE procedure. The measurement results, after taking into account the Conformity Factor in relation to the approval limits, confirmed the efficiency of aftertreatment system in terms of both gas and solid components. [ABSTRACT FROM AUTHOR]

A transient pore-scale model of particle deposit formation in 3D microstructure of a catalytic filter wall is introduced. It predicts location of particle deposits, dynamics of their growth, transition from deep to cake filtration regime as well as the impact on flow field, pressure drop and filtration efficiency. The model is validated against time-resolved X-ray tomography (XRT) data acquired during a filtration experiment. The validated model is then used in transient simulations of the soot filtration process in several different microstructures using cordierite filter substrate with varied Pd/ γ -Al 2 O 3 catalyst distribution. The sample with the coating solely inside the wall pores provides the lowest initial pressure drop but suffers from low clean filtration efficiency and high pressure drop after the cake is formed. The sample with partial on-wall coating achieves not only a higher filtration efficiency but also a lower pressure drop in long-term operation. • Soot deposition model in 3D microstructure of catalytic filter wall developed. • Transient model describes growth of particle deposits that affect flow pattern. • Model predictions validated by 4D X-ray tomography during filtration experiment. • Catalytic particulate filters with in-wall, on-wall and combined washcoat compared. • Evolution of filtration efficiency and pressure drop with soot loading predicted. [ABSTRACT FROM AUTHOR]

Gasoline particulate filters (GPFs) have recently been employed in gasoline fueled vehicles to trap particulate matter from exhaust fumes. The severe emission regulations which will be imposed in the near future will require GPFs to control the particulate number (PN) and exhaust gas (CO, HC, NOx) emissions and have low back pressure. To satisfy all these requirements, a unique catalytic design has been developed in which two different catalyst layers are applied within the GPF wall. The first catalytic layer is relatively coarse and contributes to the low back pressure and high gas conversion performance; the second is relatively dense and contributes to high PN filtration efficiency. The pore size, pore volume, and penetrating pore number were analyzed by numerical analysis followed by micro computed tomography (micro-CT). From the precise micro-CT measurement and numerical analysis of the penetrating pores, correlations were observed between the small penetration pore structure and PN filtration efficiency, and between the large penetration pore structure and back pressure. [ABSTRACT FROM AUTHOR]

• EGR-gasoline vehicles without GPF have a high risk of failing the potential SPN10 limit. • SPN10 increments from EGR gasoline vehicles are 2 ∼ 3 times higher than those without EGR. • EGR combined with the enriched fuel–air mixture is the critical reason for increased SPN10 emissions. Particles larger than 10 nm from engine exhaust are gaining global concerns. In light of this, to investigate how EGR affects gasoline vehicle SPN10 (solid particles larger than 10 nm) emissions, seven gasoline vehicles (hybrid or conventional) were studied experimentally. The results revealed that EGR vehicles risk failing the current limit (6 * 1011 #/km) more than those without EGR if the cut-off size was tightened from 23 nm to 10 nm. More specifically, during the WLTC test, EGR increased the SPN10 emission factors by 2 ∼ 3 times depending on vehicle powertrains (conventional or hybrid). Notably, SPN10 emissions increased significantly when EGR was actively engaged but showed a decrease when the EGR rate remained constant. EGR and the enriched fuel–air mixture are the critical reasons for the increased SPN10. [ABSTRACT FROM AUTHOR]

Point set filtering, which aims at reconstructing noise-free point sets from their corresponding noisy inputs, is a fundamental problem in 3D geometry processing. The main challenge of point set filtering is to preserve geometric features of the underlying geometry while at the same time removing the noise. State-of-the-art point set filtering methods still struggle with this issue: some are not designed to recover sharp features, and others cannot well preserve geometric features, especially fine-scale features. In this paper, we propose a novel approach for robust feature-preserving point set filtering, inspired by the Gaussian Mixture Model (GMM). Taking a noisy point set and its filtered normals as input, our method can robustly reconstruct a high-quality point set which is both noise-free and feature-preserving. Various experiments show that our approach can soundly outperform the selected state-of-the-art methods, in terms of both filtering quality and reconstruction accuracy. [ABSTRACT FROM AUTHOR]

Vehicles emit substantial amounts of pollutants during start periods. Engine starts mainly occur in urban areas, causing serious harm to humans. To investigate the impacts on extra cold start emissions (ECSEs), eleven China 6 vehicles with various control technologies (fuel injection, powertrain, and aftertreatment) were monitored with a portable emission measurement system (PEMS) at different temperatures. For conventional internal combustion engine vehicles (ICEVs), the average ECSEs of CO 2 increased by 24%, while the average ECSEs of NOx and particle number (PN) decreased by 38% and 39%, respectively, with air conditioning (AC) on. Gasoline direct injection (GDI) vehicles had 5% lower CO 2 ECSEs, but 261% higher NOx ECSEs and 318% higher PN ECSEs than port fuel injection (PFI) vehicles at 23 °C. The average PN ECSEs were significantly reduced by gasoline particle filters (GPFs). The GPF filtration efficiency was higher in GDI than PFI vehicles due to particle size distribution. Hybrid electric vehicles (HEVs) generated excessive PN extra start emissions (ESEs), resulting in a 518% increase compared to ICEVs. The start times of the GDI-engine HEV accounted for 11% of the whole test time, but the proportion of PN ESEs relative to total emissions were 23%. Linear simulation based on the decrease in ECSEs with increasing temperature underestimated the PN ECSEs from PFI and GDI vehicles by 39% and 21%, respectively. For ICEVs, CO ECSEs varied with temperature in a U shape with a minimum at 27 °C; NOx ECSEs decreased as ambient temperature increased; PFI vehicles generated more PN ECSEs at 32 °C than GDI vehicles, stressing the significance of ECSEs at high temperature. These results are useful for improving emission models and assessing air pollution exposure in urban aeras. [Display omitted] • Real-world extra cold start emissions (ECSEs) of eleven China 6 vehicles were measured. • GDI vehicles emitted 318% more ECSEs of PN than PFI vehicles did. • The GPF filtration efficiency for ECSEs was higher in GDI vehicles than PFI vehicles. • The ESE of PN from the GDI-engine HEV accounted for 23% of the total emission. • ECSEs of PN from PFI vehicles was 2.1 times those from GDI vehicles at 32 °C. [ABSTRACT FROM AUTHOR]

• Diffusion-limited conversion of gas in catalytic filters studied experimentally. • Several filters coated with Pt/Al2O3, using different catalyst distributions inside the wall. • CO light-off curves measured in lab reactor at increased flow rates. • CO slip above the light-off temperature indicates the extent of diffusion limitations. • Suitable catalyst coating structures are identified. In this paper we present a methodology for experimental observation of mass-transfer limitations in catalytic filter wall and their impact on the outlet conversion of gaseous pollutants. Series of cordierite filter samples are coated in the lab with a model Pt/γ-Al 2 O 3 catalyst to obtain different structures that are characterized by cross-section SEM images. Pressure drop and CO oxidation experiments are performed, focusing on the performance at higher flow rates. The presence of permanent CO slip above the light-off temperature provides a clear evidence of diffusion limitations in wall pores. While all the samples including the filter with an uncoated zone exhibit negligible CO slip at lower flow rates, there are significant differences at higher flow rates (space velocity 100 000 h−1 and above). Thanks to more uniform catalyst distribution inside the wall pores, the filters coated with the suspension d 90 = 0.3 µm exhibit a lower CO slip than the filters coated with d 90 = 4 µm. [ABSTRACT FROM AUTHOR]

A catalyst based on Pd and Rh nanoparticles supported on a Gadolinia-Doped Ceria support, a mixed O/e ionic electronic conductor (MIEC), has been prepared and washcoated in SiC catalyzed gasoline particulate filters (cGPF) prototypes. These filters have been prepared and tested for the aftertreatment of gasoline direct injection engine exhausts. Catalytic performances of various configurations of cGPFs (different catalyst loadings and locations) have been carried out near real conditions and compared with those of a commercial three-way converter TC as well as a monolith washcoated with the same MIEC-supported catalyst. Among all the samples tested, the most promising one is a GPF equipped with a SiC filtration membrane on which a catalytic layer has been washcoated. This cGPF combines good filtering efficiency, due to the membrane, and remarkable catalytic performances in presence of soot and water. The catalytic performance is greater than those of a commercial TC, in spite of a 9 times lower platinum group metal loading. This is attributed to both self-sustained electrochemical promotion and a higher availability of the active sites localized on the membrane. [ABSTRACT FROM AUTHOR]

Highlights: [•] Temperature step experiments are used to compare the dynamic cold-start behaviour. [•] A significantly delayed light-off is observed for the particulate filter. [•] A numerical simulation model for the gasoline particulate filter is presented. [•] The experimentally observed delayed light-off is well predicted by the model. [•] Sensitivity analyses identify the physical effects contributing to this delay. [ABSTRACT FROM AUTHOR]

Traditional data-independent acquisition (DIA) workflows employ off-column fractionation with data-dependent acquisition (DDA) to generate spectral libraries for data extraction. Recent advances have led to the establishment of library-independent approaches for DIA analyses. The selection of a DIA workflow may affect the outcome of plasma proteomics studies. Here, we establish a gas-phase fractionation (GPF) workflow to create DIA libraries for DIA with parallel accumulation and serial fragmentation (diaPASEF). This workflow along with three other workflows, fractionated DDA libraries, fractionated DIA libraries, and predicted spectra libraries, were evaluated on 20 plasma samples from nonsmall cell lung cancer patients with low or high levels of IL-6. We sought to optimize protein identification and total experiment time. The novel GPF workflow for diaPASEF outperformed the traditional ddaPASEF workflow in the number of identified and quantified proteins. A library-independent workflow based on predicted spectra identified and quantified the most proteins in our experiment at the cost of computational power. Overall, the choice of DIA library workflow seemed to have a limited effect on the overall outcome of a plasma proteomics experiment, but it can affect the number of proteins identified and the total experiment time., (© 2022 Wiley-VCH GmbH.)

We assessed three different technical approaches targeting the control of particle number (PN) emissions from stoichiometric direct injection gasoline vehicles. The emission performance was evaluated under both the regulated New European driving cycle and the common artemis driving cycle, conducted at both 22 and −7°C test cell temperatures. The most efficient measure was found to be the installation of a gasoline particulate filter which, with a filtration efficiency of more than 90%, effectively reduced the PN emission below the legislated diesel threshold of 6×1011 #/km, under all operating conditions examined. The use of 75–85% ethanol/gasoline blends on a flexi fuel vehicle resulted in large reductions in PN emissions, which spanned from approximately 20–35% under urban driving to an excess of 95% at motorway conditions. The emission performance of a Euro 4 vehicle utilizing a twin port/direct injection system verified the PN reduction potential offered by such strategies, exhibiting emissions in the 3-7×1011 #/km range over all hot-start tests. The fraction of nano-sized non-volatile particles that could not be detected with the legislated PN measurement procedure ranged between 10 and 35%, that is within the levels reported for late technology diesel vehicles (Mamakos et al., 2012b. Journal of Aerosol Science, 55:31–47). The study also provided evidence of volatile artefact interference downstream of the volatile particle remover when employing condensation particle counters with a cut-off size below the legislated 23nm. [ABSTRACT FROM AUTHOR]

Verticillium wilt of cotton ( Gossypium hirsutum) is a widespread and destructive disease caused by the soil-borne fungal pathogen Verticillium dahliae. In this study, a green fluorescent protein (GFP) labelled V. dahliae strain (TV7) was obtained by transforming gfp into defoliating strain V991. Strain TV7 was used to study infection and colonization of wilt resistant cotton cultivar Zhongzhimian KV1 and susceptible cultivar 861 with the aid of confocal laser scanning microscopy. The results showed that initial infection and colonization of V. dahliae in Zhongzhimian KV1 and 861 were similar. Conidia and hyphal colonies formed and penetrated in the root meristematic and elongation zones and in the conjunction of the lateral and main roots. The invaded conidia started to germinate by 2 hpi (hours post-inoculation), penetrated into the root cortex and vascular bundles, eventually colonized in the stem xylem vessels and grew restrictedly in the individual tracheae of both resistant and susceptible cultivars. Moreover, pathogen DNA could be detected by qPCR in roots and stems of both cultivars, but its content in the wilt susceptible cultivar 861 was much higher than that in the wilt resistant cultivar Zhongzhimian KV1. The results indicated that the resistant cultivar has ability to suppress V. dahliae reproduction. [ABSTRACT FROM AUTHOR]

Monodisperse packed beds have long been used as surrogate models to predict the filtration performance of particulate filters using analytical methods. In recent years, however, polydisperse packed beds have received special attention as they have the potential to better represent the microstructure of porous filter walls. In this paper, an analytical model for the filtration performance of clean polydisperse packed beds is derived based on the well-proven classical packed bed filtration theory. Predictions of the newly developed model were compared to the results of numerical simulations of the filtration performance of two polydisperse packed beds. The proposed filtration model was in considerably better agreement with the simulations than previous analytical models. [Display omitted] • Aerosol filtration through polydisperse packed beds is predicted analytically. • The model is derived from classical packed bed filtration theory. • The model fits simulations better than previous models in the literature. • Such model can potentially be used as a surrogate model for particulate filters. [ABSTRACT FROM AUTHOR]