Characterisation and separation of infectious bursal disease virus-like particles using aqueous two-phase systems

Infectious bursal disease(IBD)causes considerable economic losses in the commercial poultry industry worldwide.The principal way to control IBD virus(IBDV),the causative agent of IBD,is still through vaccination programs.Virus-like particles(VLPs)are recognised as a safe and potent recombinant vaccine platform.This research work explores the characterisation and separation of infectious bursal disease virus-like particles(IBD-VLPs)from crude feedstock.Various characteristics were studied with highperformance size-exclusion chromatography(HP-SEC),sodium dodecyl sulphate–polyacrylamide gel electrophoresis(SDS-PAGE)and transmission electron microscopy(TEM)analyses.Subsequently,the separation of IBD-VLPs using polyethylene glycol(PEG)/sodium citrate-based aqueous two-phase systems(ATPSs)was conducted and optimised.Moreover,a scale-up study of the best ATPS constituted of 15%PEG 6000,11%sodium citrate and 10%crude feedstock was performed to compare the separation performance of IBD-VLPs with and without centrifugation-assisted.The results indicated that the optimised ATPS with centrifugation-assisted for both 5 g and 50 g systems showed good recovery of IBDVLPs of>97%in the interphase between the PEG-rich top and salt-rich bottom phases.These optimised systems also showed high removal efficiencies of impurities of>95%.The results demonstrated that aqueous two-phase extraction could be a promising technology for efficient VLPs separation.

PRODUCTION IN PICHIAPASTORISAND CHARACTERIZATION OF GENETIC ENGINEERED CHIMERIC HBV/HEV VIRUS-LIKE PARTICLES

Objective To investigate the presentation of a neutralization epitope-containing peptide antigen of hepatitis E virus (HEV) on chimeric virus-like particles (VLPs) of hepatitis B surface antigen (HBsAg). MethodsThe gene fragment corresponding to amino acids (aa) 551-607 (HEnAg) of HEV capsid protein, which contains the only neutralization epitope identified to date, was fused via a synthetic glycine linker in frame with the gene of HBsAg. The resulted fusion gene was then integrated through transformation into the genome of Pichiapastorisunder the control of a methanol-induced alcohol oxidase 1 (AOX1) promoter and expressed intracellularly. The expression products in the soluble cell extracts were characterized by Western blot, ELISA, CsCl density gradient analysis, and electron microscopic visualiza-tion. Results The novel fusion protein incorporating HBsAg and the neutralization epitope-containing HEnAg was expressed successfully in Pichiapastoriswith an expected molecular weight of approximately 32 kD. It was found to possess the ability to assemble into chimeric HBV/HEV VLPs with immunological, physical and morphological characteristics akin to HBsAg particles. Not only did the chimeric VLPs show high activity levels in a HBsAg particle-specific ELISA but they were also strongly immunoreactive with hepatitis E (HE) positive human serum in a HEV specific ELISA, indicating that HEnAg peptide fragments were exposed on VLP surfaces and would be expected to be readily accessible by cells and molecules of the immune system. Similarity between chimeric VLPs to highly immunogenic HBsAg particles may confer good immuno-genicity on surface-displayed HEnAg. Conclusion The chimeric HBV/HEV VLPs produced in this study may have potential to be a recombinant HBV/HEV bivalent vaccine candidate.

Carboxyl Terminus Truncated Human Papillomavirus Type 58 L1 Protein Maintains Its Bioactivity and Ability to Form Virus-like Particles

Summary: To prepare carboxyl terminus truncated human papillomavirus type 58 L1(HPV58L1) protein and evaluate its ability to form virus-like particles, the baculovirus and Sf-9 insect cells was used to express HPV58L1 protein, and pFastBac-Htb containing HPV58L1 gene sequence of carboxyl terminus truncation was generated. Then Sf-9 cells were infected with recombinant baculovirus. After being cultured, the post-infected cells expressing-HPV58L1 protein-were harvested and analyzed by SDS-PAGE and Western blot. The ProBond~TM purification system was used for protein purification. The bio-activity of purified protein was identified by mouse erythrocyte hemagglutination assay, and the VLP formation was examined with transmission electron microscope. Our results showed that the recombinant baculovirus was generated and the Sf-9 cells was infected with the recombinant baculovirus, and after collecting, total cellular proteins were extracted. Truncated HPV58L1 protein with MW 58KD was revealed by SDS-PAGE and confirmed by Western blot. The purified L1 proteins under native condition could cause mouse erythrocytes to agglutinate and form VLP. It is concluded that HPV58L1 protein with carboxyl terminus truncation could be efficiently expressed. In baculovirus Sf-9 cells expression system, the purified protein could self-assemble into virions in vitro, and induce agglutination of mouse erythrocytes, indicating that carboxyl terminus truncation does not interfere with the bioactivity of HPV58L1 protein.

The codon-optimized capsid gene of duck circovirus can be highly expressed in yeast and self-assemble into virus-like particles

The capsid （Cap） protein, which is the only structural protein of duck circovirus （DuCV）, is the most important antigen for the development of vaccines against DuCV and the virus＇s serological diagnostic methods. In order to use yeast expression system to produce a large quantities of DuCVCap protein which is close to its natural form to display the antigen peptides perfectly, the Cap gene was optimized into the codon-optimized capsid （Opt-Cap） gene towards the preference of yeast firstly. Then, the genes of Cap and Opt-Cap were separately cloned into pPIC9K plasmid and transformed into Picha pas- toris GSl15. The strains that displayed the phenotype of Mut~ and contained multiple inserts of expression cassette were selected from those colonies. After the induction expression, the secretory type of Cap protein, which was about 43 kDa, was best expressed under 0.5% （v/v） methanol and sorbitol induction. Compared with the Cap gene, the expression level of Opt-Cap gene was much higher. What＇s more, the purified Cap protein had a good reactivity to its specific polyclone antibody and DuCV-positive serum, and it was able to self-assemble into virus-like particles （VLPs）. These VLPs, with a diameter of 15-20 nm and without a nucleic acid structure, showed a high level of similarity to DuCV particles in size and shape. All of the resultsdemonstrated that, based on the codon-optimization, it is suitable to use the P. pastoris expression system to produce DuCV VLPs on a large scale. It is the first time that a large amounts of DuCV VLPs were produced successfully in P. pastoris, which might be particularly useful for the further studies of serological diagnosis and vaccines of DuCV.

Establishment of a Human Malignant T Lymphoma Cell Line Carrying a Retrovirus-like Particles with RT Activity

We have established an IL-2 independent malignant lymphoma line (CM-1) from peripheral T lymphocytes donated by a femalc patient with nervous systcm disease, the binlogical characteristics of CM-1 cells was studied in this paper. Another T lymphocytes,such as peripheral T lymphocytes donated by a maIe patient with multiple sclerosis, could be transformed into a malignant lymphoma line by using filtered supernatant of the CM-1 cultured medium, thus the CM-2 cell line u'as estabIished. The CM-1 and CM-2 cells were transplanted by subcutaneous inoculation into nude mice, and could cause the occurrenceof typical maIignant lymphoma. The observation of eIectron micrographs suggested the existence of virions in the CM-1 and CM-2 cells, and these virions were similar toretrovirus in the ultra-structure characteristics. lt was found that this virus possesses reverse transcriptase activity. ResuIts obtained from serological assay, molecular hybridization and PCR excluded the existence of other human viruses, which were commonly usedin our laboratory. The unknown virus possesses strong transformation activity, and probably is a new retro virus. Meanwhile, the work on the clone and sequence analysis ofthis virus are being carried out.

Expression,purification and characterization of enterovirus-71 virus-like particles

AIM： Enterovirus 71 （EV71） has been implicated as the etiological agent responsible for the recent outbreaks of hand, foot and mouth disease associated with severe neurological diseases in the Asia-Pacific region. METHODS： The assembly process was hypothesized to occur via an orchestrated proteolytic processing of the P1 precursor by the viral protease 3CD. To test this hypothesis, we constructed 3 recombinant baculoviruses： Bac-P1 expressing P1; Bac-3CD expressing 3CD; and Bac-P1-3CD co-expressing P1 and 3CD. RESULTS： Both single infection by Bac-P1-3CD and coinfection by Bac-P1 and Bac-3CD resulted in correct cleavage of P1 to yield individual proteins VP0, VP1 and VP3, while the former approach yielded higher VLP production. In the cells, the structural proteins selfassembled into clusters of virus-like particles （VLP） resembling the authentic EV71 particle aggregates. After ultracentrifugation purification, the dispersed VLPs were indistinguishable from the authentic virus in size, appearance, composition and surface epitopes, as determined by SDS-PAGE, Western blot, transmission electron microscopy and immunogold labeling. CONCLUSION： Our data, for the first time, suggest that in insect cells EV71 structural proteins adopt a processing and assembly pathway similar to poliovirus assembly. The preservation of particle morphology and composition suggest that the VLP may be a valuable vaccine candidate to prevent EV71 epidemics.

Characterization of a Putative Filovirus Vaccine:Virus-Like Particles

Filoviruses are hemorrhagic fever viruses endemic to parts of Africa and the Philippines. Infection carries with it a mortality rate of up to 90% and currently there are no effective vaccines or therapeutics available to combat infection. However, the filovirus virus-like particles (VLP), which are currently under development, have been shown to be a promising vaccine candidate. They provide protection from infection in the mouse, guinea pig, and nonhuman primate models of infection, eliciting high anti-glycoprotein antibody titers and T cell responses to viral proteins. In this review, we will highlight the development of the filovirus VLP and describe the current understanding of VLP immunogenicity and correlates of protection.

A Virus-type Specific Serological Diagnosis of Flavivirus Infection Using Virus-like Particles

Many flaviviruses are emerging and reemerging pathogens, such as West Nile virus （WNV）, dengue virus （DENV）, yellow fever virus （YFV）, and Japanese encephalitis virus. Serological assay is the dominant method for diagnosis of flavivirus infections in human. Because antibodies generated during flavivirus infections cross-react with other flavivirus members, plaque reduction neutralization test （PRNT） is the only available assay to determine the infecting flavivirus type. Since PRNT requires culturing raw viruses, it must be performed in biosafety levet-3 or level-4 containment for many flaviviruses, and takes more than ten days to complete. To overcome these problems, we have developed flavivirus viral-like particles （VLPs） that could be used to replace raw viruses in the neutralization assay. The VLPs were prepared by trans packaging a luciferase-reporting replicon with viral structural proteins. This novel assay involves three simple steps： （i） VLPs from a panel of flaviviruses are incubated with flavivirus-infected sera at 37℃ for 1 h; （ii）the neutralized VLPs are used to infect Vero cells; and （iii） the infected cells are measured for luciferase activities at 22 h post-infection. The virus type whose VLP is most efficiently neutralized by the serum specimen （as quantified by the luciferase activities） is the etiologic agent. As a proof-of-concept, we show that a WNV-infected mouse serum neutralized the WNV VLP more efficiently and selectively than the DENV and YFV VLPs. Our results demonstrate that the VLP neutralization assay maintains the ＂gold standard＂ of the classic PRNT; importantly, it shortens the assay time from 〉10 days to 〈1 day, and can be performed in biosafety level-2 facility.

HPV 6b L1VIRUS-LIKE PARTICLES ELICIT HUMORAL IMMUNITY IN MICE

Objective.To test whether intramuscular,intranasal,intrarectal and intravagina l administration of HPV6b L 1 virus-like particlescould induce immune response in mice and to as sess whether intra-muscular and mucosal vaccination against HPV is feasible.Me thods.HPV6b L1proteins self-assembled into VLPs in Sf-9cell in vitro.Mic e were immunized on day0and21with50ìg HPV6b L1VLPs intramuscularly,int ranasally,intrarectally and intravagi-nally respectively.Sera were collected for testing IgG titer after a further7days and3months respec-tively.Results .After immunizations,all mice developed significant anti-HPV6b L1antibody titers in serum by7days after the second immunization.The titer of the serum I gG antibody against HPV6b L1VLPs in the intramuscularly immunized group was h igher than that in the intranasally,intrarectally and intravaginally immunized groups respectively,indicating that both muscular and mucosal administration of HPV6b L1VLPs can stimulate a systemic HPV-specific antibody response.Sera of the mice in the in-tramuscularly immunized group still maintained a high tit er of the serum IgG antibody against HPV6b L1VLPs 3months after the immunizat ion.Conclusion.The results demonstrated that the HPV6b L1VLPs maintain stro ng antigenicity.Immu-nization with HPV6b L1VLPs via intramuscular and mucos al routes,without adjuvant ,can elicit spe-cific antibody in sera.These fin dings suggest that the VLPs are able to induce protective antibodies.

Pandemic A/HIN1 2009 Influenza Virus-like Particles Elicited Higher and Broader Immune Responses than the Commercial Panenza Vaccine

Objectives： The aim was to construct 2009 pandemic A/HINI influenza VLPs （virus-like particles） and compare the immunogenicity and protection efficacy with the commercial Panenza vaccine in BALB/c mouse model. Methods： VLPs derived from influenza A/Hong Kong/01/2009 （H 1N 1 ） virus were constructed by Bac-to-Bac baculovirus expression system. VLPs were purified by sucrose density gradient ultracentrifugation and then characterized by Western blotting analysis and transmission electron microscopy. After single dose vaccination with 3 lag of VLPs and equal amount of Panenza vaccine, the immune responses and efficacy of protection induced by VLPs were compared with those elicited by the Panenza vaccine in 6-8 weeks old female BALB/c mice. Key findings： VLPs could induce higher antibody titer as determined by hemagglutinin inhibition and microneutralization assay. Furthermore, we demonstrated that VLPs induced better antibody response to neuraminidase. In addition, VLP vaccinated mice had stronger cell-mediated immune response. As a result, our VLPs conferred 100% protection while the Panenza vaccine only conferred 67% protection. Conclusion： From the results, we concluded that influenza VLPs are highly immunogenic and they are promising to be developed as an alternative strategy to vaccine production in order to control the spread of influenza viruses.

Construction and Production of FluorescentPapillom avirus-like Particles

The green fluorescent protein (GFP) from the jellyfish Aequorea victoria has attracted widespread interest since it was demonstrated to be fluorescent in vivo when expressed in other organisms. In order to investigate papillomavirus life cycle which hampered by the unavailability of conventional cell culture system, we constructed a chimeric bovine papillomavirus (BPV) type 1 virus like particles (VLPs) containing GFP. It was found that fluorescent VLPs could be assembled from L2 protein in which GFP is inserted into the N terminal region of L2 (aa 88). The fluorescent VLPs could also be assembled from a GFP/L2 fusion protein in which part of the L2 sequence had been deleted. In vitro , fluorescent VLPs could bind to CV 1 cells, and this VLP/cell interaction could be analyzed by FACS assay. These results demonstrated that GFP could incorporate into BPV1 VLPs without disruption of the VLP structure. Fluorescent VLPs might be a useful tool for study of papillomavirus virus/cell interaction.

Drosophila X virus-like particles as delivery carriers for improved oral insecticidal efficacy of scorpion Androctonus australis peptide against the invasive fruit fly,Drosophila suzukii

Insect-specific neurotoxic peptides derived from the venoms of scorpions and spiders can cause acute paralysis and death when injected into insects,offering a promising insecticidal component for insect pest control.However,effective delivery systems are required to help neurotoxic peptides pass through the gut barrier into the hemolymph,where they can act.Here,we investigated the potential of a novel nanocarrier,Drosophila X virus-like particle(DXV-VLP),for delivering a neurotoxin from the scorpion Androctonus australis Hector(AaIT)against the invasive pest fruit fly,Drosophila suzuki.Our results show that the fusion proteins of DXV polyproteins with AalT peptide at their Ctermini could be sufficiently produced in Lepidoptera Hi5 cells in a soluble form using the recombinant baculovirus expression system,and could self-assemble into VLPs with similar particle morphology and size to authentic DXV virions.In addition,the AalT peptides displayed on DXV-VLPs retained their toxicity,as demonstrated in injection bioassays that resulted in severe mortality(72%)in adults after 72 h.When fed to adults,mild mortality was observed in the group treated with DXV-AalT(38%),while no mortality occurred in the group treated with AaIT peptide,thus indicating the significant role of DXV-VLPs in delivering AalT peptides.Overall,this proof-of-concept study demonstrates for the first time that VLPs can be exploited to enhance oral delivery of insect-specific neurotoxic peptides in the context of pest control.Moreover,it provides insights for further improvements and potentially the development of neurotoxin-based bioinsecticides and/or transgenic crops for insect pest control.

Zika Virus Baculovirus-Expressed Virus-Like Particles Induce Neutralizing Antibodies in Mice

The newly emerged mosquito-borne Zika virus(ZIKV) strains pose a global challenge owing to its ability to cause microcephaly and neurological disorders. Several ZIKV vaccine candidates have been proposed, including inactivated and live attenuated virus vaccines, vector-based vaccines, DNA and RNA vaccines. These have been shown to be efficacious in preclinical studies in mice and nonhuman primates, but their use will potentially be a threat to immunocompromised individuals and pregnant women. Virus-like particles(VLPs) are empty particles composed merely of viral proteins, which can serve as a safe and valuable tool for clinical prevention and treatment strategies. In this study, we used a new strategy to produce ZIKV VLPs based on the baculovirus expression system and demonstrated the feasibility of their use as a vaccine candidate. The pre-membrane(prM) and envelope(E) proteins were co-expressed in insect cells and selfassembled into particles similar to ZIKV. We found that the ZIKV VLPs could be quickly and easily prepared in large quantities using this system. The VLPs were shown to have good immunogenicity in immunized mice, as they stimulated high levels of virus neutralizing antibody titers, ZIKV-specific IgG titers and potent memory T cell responses. Thus, the baculovirus-based ZIKV VLP vaccine is a safe, effective and economical vaccine candidate for use against ZIKV.

Design and immunogenicity assessment of HIV-1 virus-like particles as a candidate vaccine

The rapid growth of the global HIV/AIDS epidemic makes it a high priority to develop an effective vaccine.Since a live attenuated or inactivated HIV vaccine is not likely to be approved for clinical application due to safety concerns,HIV virus like particles(VLPs) offer an attractive alternative because they are considered safer since they lack viral genome.We got a stable eukaryotic cell line by G418 resistance selection,engineered to express the HIV-1 structure protein Gag and Env efficiently and stably.We confirmed the presence of Gag and Env proteins in the cell culture supernatant and that they could self-assemble into VLPs.These VLPs were found to be able to elicit specific humoral and cellular immune response after immunization without any adjuvant.

Chimeric Newcastle Disease Virus-like Particles Containing DC-Binding Peptide-Fused Haemagglutinin Protect Chickens from Virulent Newcastle Disease Virus and H9N2 Avian Influenza Virus Challenge

Newcastle disease virus(NDV)and H9N2 subtype Avian influenza virus(AIV)are two notorious avian respiratory pathogens that cause great losses in the poultry industry.Current inactivated commercial vaccines against NDV and AIV have the disadvantages of inadequate mucosal responses,while an attenuated live vaccine bears the risk of mutation.Dendritic cell(DC)targeting strategies are attractive for their potent mucosal and adaptive immune-stimulating ability against respiratory pathogens.In this study,DC-binding peptide(DCpep)-decorated chimeric virus-like particles(cVLPs),containing NDV haemagglutinin–neuraminidase(HN)and AIV haemagglutinin(HA),were developed as a DC-targeting mucosal vaccine candidate.DCpep-decorated cVLPs activated DCs in vitro,and induced potent immune stimulation in chickens,with enhanced secretory immunoglobulin A(sIgA)secretion and splenic T cell differentiation.40μg cVLPs can provide full protection against the challenge with homologous,heterologous NDV strains,and AIV H9N2.In addition,DCpep-decorated cVLPs could induce a better immune response when administered intranasally than intramuscularly,as indicated by robust s IgA secretion and a reduced virus shedding period.Taken together,this chimericVLPs are a promising vaccine candidate to control NDV and AIV H9N2 and a useful platform bearing multivalent antigens.

Induction of virus-neutralizing antibodies and T cell responses by dengue virus type 1 virus-like particles prepared from Pichia pastoris

Background Dengue is currently a significant global health problem but no vaccines are available against the four dengue serotypes virus infections. The development of safe and effective vaccines has been hampered by the requirement of conferring complete protection against all four dengue serotypes and the lack of a convenient animal model. Virus-like particles （VLPs） have emerged as a promising subunit vaccine candidate. One strategy of vaccine development is to produce a tetravalent dengue subunit vaccine by mixing recombinant VLPs, corresponding to all four dengue virus serotypes. Towards this end, this study aimed to establish a Pichia pastoris （P. pastoris） expression system for production of dengue virus type 1 （DENV-1） VLPs and evaluate the humoral and cellular immune response of this particle in mice. Methods A recombinant yeast P. pastoris clone containing prM and E genes of DENV-1 was constructed and DENV-1 VLPs expressed by this clone were analyzed by sucrose density gradient centrifugation, Western blotting, and transmission electron microscope. Groups of mice were immunized by these particles plus adjuvant formulations, then mice were tested by ELISA and neutralization assay for humoral immune response, and by lymphocyte proliferation and cytokine production assays for a cellular immune response. Results Our data demonstrated that recombinant DENV-1 VLPs consisting of prM and E protein were successfully expressed in the yeast P. pastoris. Sera of VLPs immunized mice were shown to contain a high-titer of antibodies and the neutralization assay suggested that those antibodies neutralized virus infection in vitro. Data from the T lymphocyte proliferation assay showed proliferation of T cell, and ELISA found elevated secretion levels of interferon IFN-γ and IL-4. Conclusions P. pastoris-expressed DENV-1 VLPs can induce virus neutralizing antibodies and T cell responses in immunized mice. Using P. pastoris to produce VLPs offers a promising and economic strategy for dengue virus vaccine development.

Fabrication of virus-like particles with strip-pattern surface：A two-step self-assembly approach

Spherical nanostructures with striped patterns on the surfaces resembling the essential structures of natural virus particles were constructed through a two-step self-assembly approach of polystyrene-boligo（acrylic acid）（PS-b-oligo-AA） and poly（γ-benzyI L-glutamate）-b-poly（ethylene glycol）（PBLG-bPEG） copolymer mixtures in solution.On the basis of difference in hydrophilicity and self-assembly properties of the two copolymers,the two-step self-assembly process is realized.It was found that PS-boligo-AA copolymers formed spherical aggregates by adding a certain amount of water into polymer solutions in the first step.In the second step,two polymer solutions were mixed and water was further added,inducing the self-assembly of PBLG-b-PEG on the surfaces of PS-b-oligo-AA spheres to form striped patterns.In-depth study was conducted for the indispensable defects of striped patterns which are dislocations and ＋1/2 disclinations.The influencing factors such as the mixing ratio of two copolymers and the added water content in the first step on the morphology and defects of the striped patterns were investigated.This work not only presents an idea to interpret mechanism of the cooperative self-assembly behavior,but also provides an effective approach to construct virus-like particles and other complex structures with controllable morphology.

Study of deep transportation and plugging performance of deformable gel particles in porous media

Deformable gel particles(DGPs) possess the capability of deep profile control and flooding. However, the deep migration behavior and plugging mechanism along their path remain unclear. Breakage, an inevitable phenomenon during particle migration, significantly impacts the deep plugging effect. Due to the complexity of the process, few studies have been conducted on this subject. In this paper, we conducted DGP flow experiments using a physical model of a multi-point sandpack under various injection rates and particle sizes. Particle size and concentration tests were performed at each measurement point to investigate the transportation behavior of particles in the deep part of the reservoir. The residual resistance coefficient and concentration changes along the porous media were combined to analyze the plugging performance of DGPs. Furthermore, the particle breakage along their path was revealed by analyzing the changes in particle size along the way. A mathematical model of breakage and concentration changes along the path was established. The results showed that the passage after breakage is a significant migration behavior of particles in porous media. The particles were reduced to less than half of their initial size at the front of the porous media. Breakage is an essential reason for the continuous decreases in particle concentration, size, and residual resistance coefficient. However, the particles can remain in porous media after breakage and play a significant role in deep plugging. Higher injection rates or larger particle sizes resulted in faster breakage along the injection direction, higher degrees of breakage, and faster decreases in residual resistance coefficient along the path. These conditions also led to a weaker deep plugging ability. Smaller particles were more evenly retained along the path, but more particles flowed out of the porous media, resulting in a poor deep plugging effect. The particle size is a function of particle size before injection, transport distance, and different injection parameters(injection rate or the diameter ratio of DGP to throat). Likewise, the particle concentration is a function of initial concentration, transport distance, and different injection parameters. These models can be utilized to optimize particle injection parameters, thereby achieving the goal of fine-tuning oil displacement.

Mathematical modeling and simulations of stress mitigation by coating polycrystalline particles in lithium-ion batteries

A chemo-mechanical model is developed to investigate the effects on the stress development of the coating of polycrystalline Ni-rich LiNixMnyCo_(z)O_(2)(x≥0.8)(NMC)particles with poly(3,4-ethylenedioxythiophene)(PEDOT).The simulation results show that the coating of primary NMC particles significantly reduces the stress generation by efficiently accommodating the volume change associated with the lithium diffusion,and the coating layer plays roles both as a cushion against the volume change and a channel for the lithium transport,promoting the lithium distribution across the secondary particles more homogeneously.Besides,the lower stiffness,higher ionic conductivity,and larger thickness of the coating layer improve the stress mitigation.This paper provides a mathematical framework for calculating the chemo-mechanical responses of anisotropic electrode materials and fundamental insights into how the coating of NMC active particles mitigates stress levels.

Mass transfer enhancement and hydrodynamic performance with wire mesh coupling solid particles in bubble column reactor

It is of vital significance to investigate mass transfer enhancements for chemical engineering processes.This work focuses on investigating the coupling influence of embedding wire mesh and adding solid particles on bubble motion and gas-liquid mass transfer process in a bubble column.Particle image velocimetry(PIV)technology was employed to analyze the flow field and bubble motion behavior,and dynamic oxygen absorption technology was used to measure the gas-liquid volumetric mass transfer coefficient(kLa).The effect of embedding wire mesh,adding solid particles,and wire mesh coupling solid particles on the flow characteristic and kLa were analyzed and compared.The results show that the gas-liquid interface area increases by 33%-72%when using the wire mesh coupling solid particles strategy compared to the gas-liquid two-phase flow,which is superior to the other two strengthening methods.Compared with the system without reinforcement,kLa in the bubble column increased by 0.5-1.8 times with wire mesh coupling solid particles method,which is higher than the sum of kLa increases with inserting wire mesh and adding particles,and the coupling reinforcement mechanism for affecting gas-liquid mass transfer process was discussed to provide a new idea for enhancing gas-liquid mass transfer.