Microplastics(MPs)are ubiquitous in the environment,continuously undergo aging processes and release toxic chemical substances.Understanding the environmental behaviors of MPs is critical to accurately evaluate their ...Microplastics(MPs)are ubiquitous in the environment,continuously undergo aging processes and release toxic chemical substances.Understanding the environmental behaviors of MPs is critical to accurately evaluate their long-term ecological risk.Generalized twodimensional correlation spectroscopy(2D-COS)is a powerful tool for MPs studies,which can dig more comprehensive information hiding in the conventional one-dimensional spectra,such as infrared(IR)and Raman spectra.The recent applications of 2D-COS in analyzing the behaviors and fates of MPs in the environment,including their aging processes,and interactions with natural organicmatter(NOM)or other chemical substances,were summarized systematically.The main requirements and limitations of current approaches for exploring these processes are discussed,and the corresponding strategies to address these limitations and drawbacks are proposed as well.Finally,new trends of 2D-COS are prospected for analyzing the properties and behaviors of MPs in both natural and artificial environmental processes.展开更多
Objective:To evaluate the effectiveness of music therapy on the anxiety level and physiological response of patients undergoing ophthalmic surgery.Methods:Relevant randomized controlled trials that compared the combin...Objective:To evaluate the effectiveness of music therapy on the anxiety level and physiological response of patients undergoing ophthalmic surgery.Methods:Relevant randomized controlled trials that compared the combined effect of music therapy for patients undergoing ophthalmic surgery were included.Four English databases and three Chinese databases were searched from inception to Jan.2022.Two reviewers independently performed data extraction and risk of bias assessments.The Cochrane Collaboration tool was used to assess the risk of bias.Meta-analysis was performed using Review Manager 5.3.The outcomes were overall anxiety,blood pressure,heart rate and pain.Results:A total of 11 trials with 1,469 participants were included in the meta-analysis.Compared to standard care,music therapy had a good effect on reducing the anxiety levels of patients undergoing ophthalmic surgery(P<0.05).The results also suggested that music therapy produced a significant improvement in blood pressure(P<0.05)and heart rate(P<0.05).The visual analogue scale(VAS)showed that music therapy significantly reduced pain compared to standard care(P<0.05).Conclusions:This meta-analysis provided evidence that music therapy has an obvious effect on relieving anxiety levels,while it is also more effective in alleviating pain and improving physiological responses than standard care alone.Our findings may provide accurate evidence-based guidance for the clinical implementation of music therapy.In the future,more high-quality studies are required for verifying these results.展开更多
Wastewater reclamation and reuse has been proved to be an effective way to relieve the fresh water crisis.However, toxic contaminants remaining in reclaimed water could lead to potential risk for reuse, and the conven...Wastewater reclamation and reuse has been proved to be an effective way to relieve the fresh water crisis.However, toxic contaminants remaining in reclaimed water could lead to potential risk for reuse, and the conventional water quality standards have difficulty guaranteeing the safety of reclaimed water.Bioassays can vividly reflect the integrated biological effects of multiple toxic substances in water as a whole, and could be a powerful tool for evaluating the safety of reclaimed water.Therefore, in this study, the advantages and disadvantages of using bioassays for evaluating the safety of reclaimed water were compared with those of conventional water quality standards.Although bioassays have been widely used to describe the toxic effects of reclaimed water and treatment efficiency of reclamation techniques, a single bioassay cannot reflect the complex toxicity of reclaimed water, and a battery of bioassays involving multiple biological effects or in vitro tests with specific toxicity mechanisms would be recommended.Furthermore, in order to evaluate the safety of reclaimed water based on bioassay results, various methods including potential toxicology, the toxicity unit classification system, and a potential eco-toxic effects probe are summarized as well.Especially, some integrated ranking methods based on a bioassay battery involving multiple toxicity effects are recommended as useful tools for evaluating the safety of reclaimed water, which will benefit the promotion and guarantee the rapid development of the reclamation and reuse of wastewater.展开更多
Wastewater reclamation and reuse is an increasing global project,while the reclamation treatment on wastewater does not completely remove all pollutants in water.The residual pollutants in reclaimed water would cause ...Wastewater reclamation and reuse is an increasing global project,while the reclamation treatment on wastewater does not completely remove all pollutants in water.The residual pollutants in reclaimed water would cause potential risk on human health and ecosystem safety during the long-term use.It is impossible to analyze and control all pollutants one by one in practice,therefore,identification and control of priority pollutants will be efficient strategy to ensure the safe use of reclaimed water.An integrated three-step methodology for identifying priority pollutants in reclaimed water was proposed in this study.First,a comprehensive literature survey on the occurrence of pollutants in reclaimed water was conducted,and a dataset D PR for pollutants occurrence in reclaimed water was established,containing 1,113 pollutants.Second,611 chemicals that had been recommended as hazardous pollutants for various water bodies in previous literatures were summarized,and a dataset D HP for hazardous pollutants in water was obtained.Third,meta-analysis on these two datasets(D PR and D HP)was performed,a new dataset D HPR for hazardous pollutants in reclaimed water was established,including 265 candidates.Finally,59 substances out of dataset D HPR were identified as priority pollutants for reclaimed water based on their recommendation frequency.It is expected that this synthetical methodology will provide powerful support for scientific evaluating and managing water pollution and ensuring safe use of reclaimed water.展开更多
The clustered regularly interspaced short palindromic repeats(CRISPR)–CRISPR-associated protein(Cas) system has been widely used for genome editing. In this system, the cytosine base editor(CBE) and adenine base edit...The clustered regularly interspaced short palindromic repeats(CRISPR)–CRISPR-associated protein(Cas) system has been widely used for genome editing. In this system, the cytosine base editor(CBE) and adenine base editor(ABE) allow generating precise and irreversible base mutations in a programmable manner and have been used in many different types of cells and organisms. However, their applications are limited by low editing efficiency at certain genomic target sites or at specific target cytosine(C) or adenine(A) residues. Using a strategy of combining optimized synergistic core components, we developed a new multiplex super-assembled ABE(sABE) in rice that showed higher base-editing efficiency than previously developed ABEs. We also designed a new type of nuclear localization signal(NLS) comprising a FLAG epitope tag with four copies of a codon-optimized NLS(F4NLS^(r2)) to generate another ABE named F4NLS-sABE. This new NLS increased editing efficiency or edited additional A at several target sites. A new multiplex super-assembled CBE(sCBE) and F4NLS^(r2) involved F4NLS-sCBE were also created using the same strategy. F4NLS-sCBE was proven to be much more efficient than sCBE in rice. These optimized base editors will serve as powerful genome-editing tools for basic research or molecular breeding in rice and will provide a reference for the development of superior editing tools for other plants or animals.展开更多
Base editing, as an expanded clustered regularly interspaced short palindromic repeats(CRISPR)-Cas genome editing strategy, permits precise and irreversible nucleotide conversion. SaKKH, an efficient variant of a Cas9...Base editing, as an expanded clustered regularly interspaced short palindromic repeats(CRISPR)-Cas genome editing strategy, permits precise and irreversible nucleotide conversion. SaKKH, an efficient variant of a Cas9 ortholog from Staphylococcus aureus(SaCas9), is important in genome editing because it can edit sites with HHHAAT protospacer adjacent motif(PAM) that the canonical Streptococcus pyogenes Cas9(SpCas9) or its variants(e.g. xCas9, Cas9-NG) cannot. However, several technical parameters of SaKKH involved base editors have not been well defined and this uncertainty limits their application. We developed an effective multiplex cytosine base editor(SaKKHn-pBE) and showed that it recognized NNARRT, NNCRRT, NNGRGT, and NNTRGT PAMs. Based on 27 targets tested, we defined technical parameters of SaKKHn-pBE including the editing window, the preferred sequence context, and the mutation type. The editing efficiency was further improved by modification of the SaKKH sgRNA. These advances can be applied in future research and molecular breeding in rice and other plants.展开更多
This study was designed to summarize the key points of surgical cooperation involving penetrating corneal transplantation combined with implantation of keratoprosthesis. Preoperative preparation and intraoperative pro...This study was designed to summarize the key points of surgical cooperation involving penetrating corneal transplantation combined with implantation of keratoprosthesis. Preoperative preparation and intraoperative procedures were fully implemented to ensure cooperation with the physicians,.to observe the the severity of the disease, and to guarantee the success of the surgery.展开更多
Metallised film capacitors(MFCs)are renowned for their unique self-healing(SH)properties,which bestow them with exceptional reliability and stability in the face of intense electric fields,high voltages,and pulse powe...Metallised film capacitors(MFCs)are renowned for their unique self-healing(SH)properties,which bestow them with exceptional reliability and stability in the face of intense electric fields,high voltages,and pulse power applications.Nonetheless,the exploration of SH characteristics concerning single-layer dielectric film remains insufficient for advancing MFC reliability evaluation.To establish the theoretical correlation of SH characteristics from the device to the film in the MFCs,this work developed a simulation model to analyse the SH dynamic behaviour in the MFCs.The effects of coupling capacitors,arc resistance and insulation resistance on the macroscopic characteristics(voltage drop and pulse current)are focused during the SH process in MFCs.The results indicate that SH is primarily associated with the voltage drop duration rather than the sampling current.Consequently,the SH process in MFC is characterised as an abrupt decrease in voltage to its minimum value.This refinement enhances the SH energy dissipation model of MFC.The quantified relationship between the macroscopic characteristics and microstructure evolution(polypropylene decomposition and aluminium electrode vaporisation)is established in MFCs under diverse SH energy levels.As SH energy and duration increase,the proportion of energy attributed to polypropylene decomposition increases,resulting in multi-layer ablation and adhesion within the metallised film and a pronounced deterioration in MFC electrical performance.The examination of macro-micro perspectives sheds new light on the intricate mechanisms governing the SH behaviour in MFCs,offering valuable insights for the advancement of their design,reliability evaluation,and performance optimisation in diverse electrical applications.展开更多
The development of CRISPR/Cas9-mediated base editing has made genomic modification more efficient. However, selection of genetically modified cells from millions of treated cells, especially plant cells, is still chal...The development of CRISPR/Cas9-mediated base editing has made genomic modification more efficient. However, selection of genetically modified cells from millions of treated cells, especially plant cells, is still challenging. In this study, an efficient surrogate reporter system based on a defective hygromycin resistance gene was established in rice to enrich base-edited cells. After step-by-step optimization, the Discriminated sgRNAs-based SurroGate system (DisSUGs) was established by artificially differentiating the editing abilities of a wild-type single guide RNA (sgRNA) targeting the surrogate reporter gene and an enhanced sgRNA targeting endogenous sites. The DisSUGs enhanced the efficiency of screening base-edited cells by 3- to 5-fold for a PmCDA1-based cytosine-to-tyrosine base editor (PCBE), and 2.5- to 6.5-fold for an adenine base editor (ABE) at endogenous targets. These targets showed editing efficiencies of <25% in the conventional systems. The DisSUGs greatly enhanced the frequency of homozygous substitutions and expanded the activity window slightly for both a PCBE and an ABE. Analyses of the total number of single-nucleotide variants from whole-genome sequencing revealed that, compared with the no-enrichment PCBE strategy, the DisSUGs did not alter the frequency of genome-wide sgRNA-independent off-target mutations, but slightly increased the frequency of target-dependent off-target mutations. Collectively, the DisSUGs developed in this study greatly enhances the efficiency of screening plant base-edited cells and will be a useful system in future applications.展开更多
The 2050 carbon-neutral vision spawns a novel energy structure revolution,and the construction of the future energy structure is based on equipment innovation.Insulating material,as the core of electrical power equipm...The 2050 carbon-neutral vision spawns a novel energy structure revolution,and the construction of the future energy structure is based on equipment innovation.Insulating material,as the core of electrical power equipment and electrified transportation asset,faces unprecedented challenges and opportunities.The goal of carbon neutral and the urgent need for innovation in electric power equipment and electrification assets are first discussed.The engineering challenges constrained by the insulation system in future electric power equipment/devices and electrified transportation assets are investigated.Insulating materials,including intelligent insulating material,high thermal conductivity insulating material,high energy storage density insulating material,extreme environment resistant insulating material,and environmental-friendly insulating material,are cat-egorised with their scientific issues,opportunities and challenges under the goal of carbon neutrality being discussed.In the context of carbon neutrality,not only improves the understanding of the insulation problems from a macro level,that is,electrical power equipment and electrified transportation asset,but also offers opportunities,remaining issues and challenges from the insulating material level.It is hoped that this paper en-visions the challenges regarding design and reliability of insulations in electrical equipment and electric vehicles in the context of policies towards carbon neutrality rules.The authors also hope that this paper can be helpful in future development and research of novel insulating materials,which promote the realisation of the carbon-neutral vision.展开更多
Metallised polypropylene film capacitors(MPPFCs)are widely used in power electronics and are generally degraded by elevated temperatures.This work aims to determine the relationships between the structural changes of ...Metallised polypropylene film capacitors(MPPFCs)are widely used in power electronics and are generally degraded by elevated temperatures.This work aims to determine the relationships between the structural changes of MPPFC and the microstructural variations of the PP film during the thermal ageing of MPPFC at 100℃ for 38 days.The capacitance of MPPFC has a slight decrease during thermal ageing.However,the breakdown voltage of the MPPFC decreases by 39.4%by the ageing.The partial discharge(PD)number of MPPFC increases linearly with ageing time.The tear-down analysis of the MPPFC reveals that the molecular structure of the PP film has not been altered but has led to molecular chain scission and the generation of some polar fragments/groups.Meanwhile,the relative permittivity of the PP films rises as the ageing time increases.Moreover,thermal ageing causes the conversion of aluminum to alumina in the metallised electrode,which is hydrophilic for polar groups and leads to an adhesion effect between the metallised electrodes and the PP film.Contact angle measurements prove that the surface hydrophilicity of the PP sample increased after thermal ageing.Therefore,the PD/breakdown voltage in the MPPFC increases/decreases due to the uneven adhesion of the metallised PP film.展开更多
Dear Editor,Base editors(BEs),including cytosine base editor(CBE)and adenine base editor(ABE),have been widely used to generate irreversible nucleotide substitution in plants and animals.However,their wide application...Dear Editor,Base editors(BEs),including cytosine base editor(CBE)and adenine base editor(ABE),have been widely used to generate irreversible nucleotide substitution in plants and animals.However,their wide applications are largely hindered by the strict NG protospacer adjacent motif(PAM)sequences recognized by Streptococcus pyogenes Cas9(SpCas9)and its engineered variants,such as SpCas9-NG and xCas9(Hua et al.,2019;Ren et al.,2019;Wu et al.,2019;Zhong et al.,2019;Zhang et al.,2020).Most recently,it was reported that three new SpCas9 variants,SpCas9-NRRH,SpCas9-NRTH,and SpCas9-NRCH,could recognize non-G PAMs(NRNH,where R is A or G and H is A,C,or T)in human cells(Miller et al.,2020).Meanwhile,SPRY,another new SpCas9 variant,was developed to greatly expand the editing scope of BEs to nearly PAMless(Walton et al.,2020).In this study,we generated a series of efficient BE toolkits and almost achieved C-to-T mutation without PAM restriction except for NTG PAM,and largely expanded A-to-G mutation scope in stable transformed rice,providing a reference for application in other plants.展开更多
The flashover strength of epoxy(EP)insulations in the High voltage direct current applications of future energy grids can be improved by tailoring their surface condition.This work aims to improve the DC surface flash...The flashover strength of epoxy(EP)insulations in the High voltage direct current applications of future energy grids can be improved by tailoring their surface condition.This work aims to improve the DC surface flashover characteristics of EP after being treated with sandpaper of different gradings.Samples with virgin EP and homogenously modified EP considering varying surface roughness(R_(a)=0.54,3.16,5.24,and 8.35μm)are prepared.Different experimental characterisations,such as water contact angle,surface intrinsic conductivity,surface voltages,flashover strength,and trap distributions are conducted and evaluated to analyse the difference between virgin and treated EP.Moreover,based on the obtained experimental results of homogenously treated EP and theoretical analysis,the concept of surface functionally graded materials(SFGMs)is put forward.The flashover voltages of homogenously treated EP are augmented significantly compared to virgin EP regardless of the voltage polarity and enhanced by enhancing the surface roughness.The sample T_(Model‐C) with SFGM design shows a 45.02%and 43.75%improvement in the negative and positive flashover voltages than that of the virgin EP.In the end,COMSOL simulations are conducted to justify the experimental findings and to analyse the difference between virgin and modified samples in terms of electric field distribution.展开更多
In this work,the boron nitride(BN)nanosheets were dispersed in natural esters to fabricate the dielectric nanofluid.Microstructures and chemical compositions of the nanosized BN are determined.The stability,viscosity,...In this work,the boron nitride(BN)nanosheets were dispersed in natural esters to fabricate the dielectric nanofluid.Microstructures and chemical compositions of the nanosized BN are determined.The stability,viscosity,and thermal conductivity of the BN nanofluid,were obtained.And the dissipation factor,electrical conductivity,and relative permittivity of the BN nanofluid,were measured.The ion mobilities and migrating times of the nanofluid were measured under different volumetric fractions of BN nanosheets and temperatures.Results show that the electrical conductivity and dissipation factor of the nanofluid decreased by 54%and 48%with the addition of only 0.1%of BN nano-sheets under 110°C.Both the half-reduced carrier mobility of the nanofluid and the declined ion concentration by blocking of BN nanosheet contributed to the exponentially reduced electrical conductivity and enhanced dielectric performances of the BN nano-fluid.The suppression coefficient k is proposed to quantitatively describe the hinder effect of ion migration in nanofluids by 2D BN nanosheet.Results provide a strategy to design and develop advanced nanofluids with low-dielectric loss by aids of surface adsorption of ion and steric hindrance of 2D nanosheets.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52293444 and 22076209)the Key R&D Project of Ningxia(No.2021BEG02006).
文摘Microplastics(MPs)are ubiquitous in the environment,continuously undergo aging processes and release toxic chemical substances.Understanding the environmental behaviors of MPs is critical to accurately evaluate their long-term ecological risk.Generalized twodimensional correlation spectroscopy(2D-COS)is a powerful tool for MPs studies,which can dig more comprehensive information hiding in the conventional one-dimensional spectra,such as infrared(IR)and Raman spectra.The recent applications of 2D-COS in analyzing the behaviors and fates of MPs in the environment,including their aging processes,and interactions with natural organicmatter(NOM)or other chemical substances,were summarized systematically.The main requirements and limitations of current approaches for exploring these processes are discussed,and the corresponding strategies to address these limitations and drawbacks are proposed as well.Finally,new trends of 2D-COS are prospected for analyzing the properties and behaviors of MPs in both natural and artificial environmental processes.
文摘Objective:To evaluate the effectiveness of music therapy on the anxiety level and physiological response of patients undergoing ophthalmic surgery.Methods:Relevant randomized controlled trials that compared the combined effect of music therapy for patients undergoing ophthalmic surgery were included.Four English databases and three Chinese databases were searched from inception to Jan.2022.Two reviewers independently performed data extraction and risk of bias assessments.The Cochrane Collaboration tool was used to assess the risk of bias.Meta-analysis was performed using Review Manager 5.3.The outcomes were overall anxiety,blood pressure,heart rate and pain.Results:A total of 11 trials with 1,469 participants were included in the meta-analysis.Compared to standard care,music therapy had a good effect on reducing the anxiety levels of patients undergoing ophthalmic surgery(P<0.05).The results also suggested that music therapy produced a significant improvement in blood pressure(P<0.05)and heart rate(P<0.05).The visual analogue scale(VAS)showed that music therapy significantly reduced pain compared to standard care(P<0.05).Conclusions:This meta-analysis provided evidence that music therapy has an obvious effect on relieving anxiety levels,while it is also more effective in alleviating pain and improving physiological responses than standard care alone.Our findings may provide accurate evidence-based guidance for the clinical implementation of music therapy.In the future,more high-quality studies are required for verifying these results.
基金supported by the National Key R&D Program of China(Nos.2016YFE0118800,2018YFC0406301).
文摘Wastewater reclamation and reuse has been proved to be an effective way to relieve the fresh water crisis.However, toxic contaminants remaining in reclaimed water could lead to potential risk for reuse, and the conventional water quality standards have difficulty guaranteeing the safety of reclaimed water.Bioassays can vividly reflect the integrated biological effects of multiple toxic substances in water as a whole, and could be a powerful tool for evaluating the safety of reclaimed water.Therefore, in this study, the advantages and disadvantages of using bioassays for evaluating the safety of reclaimed water were compared with those of conventional water quality standards.Although bioassays have been widely used to describe the toxic effects of reclaimed water and treatment efficiency of reclamation techniques, a single bioassay cannot reflect the complex toxicity of reclaimed water, and a battery of bioassays involving multiple biological effects or in vitro tests with specific toxicity mechanisms would be recommended.Furthermore, in order to evaluate the safety of reclaimed water based on bioassay results, various methods including potential toxicology, the toxicity unit classification system, and a potential eco-toxic effects probe are summarized as well.Especially, some integrated ranking methods based on a bioassay battery involving multiple toxicity effects are recommended as useful tools for evaluating the safety of reclaimed water, which will benefit the promotion and guarantee the rapid development of the reclamation and reuse of wastewater.
基金supported by the National Key R&D Program of China(Nos.2018YFC0406300,2016YFE0118800)。
文摘Wastewater reclamation and reuse is an increasing global project,while the reclamation treatment on wastewater does not completely remove all pollutants in water.The residual pollutants in reclaimed water would cause potential risk on human health and ecosystem safety during the long-term use.It is impossible to analyze and control all pollutants one by one in practice,therefore,identification and control of priority pollutants will be efficient strategy to ensure the safe use of reclaimed water.An integrated three-step methodology for identifying priority pollutants in reclaimed water was proposed in this study.First,a comprehensive literature survey on the occurrence of pollutants in reclaimed water was conducted,and a dataset D PR for pollutants occurrence in reclaimed water was established,containing 1,113 pollutants.Second,611 chemicals that had been recommended as hazardous pollutants for various water bodies in previous literatures were summarized,and a dataset D HP for hazardous pollutants in water was obtained.Third,meta-analysis on these two datasets(D PR and D HP)was performed,a new dataset D HPR for hazardous pollutants in reclaimed water was established,including 265 candidates.Finally,59 substances out of dataset D HPR were identified as priority pollutants for reclaimed water based on their recommendation frequency.It is expected that this synthetical methodology will provide powerful support for scientific evaluating and managing water pollution and ensuring safe use of reclaimed water.
基金supported by the Beijing Scholars Program[BSP041]。
文摘The clustered regularly interspaced short palindromic repeats(CRISPR)–CRISPR-associated protein(Cas) system has been widely used for genome editing. In this system, the cytosine base editor(CBE) and adenine base editor(ABE) allow generating precise and irreversible base mutations in a programmable manner and have been used in many different types of cells and organisms. However, their applications are limited by low editing efficiency at certain genomic target sites or at specific target cytosine(C) or adenine(A) residues. Using a strategy of combining optimized synergistic core components, we developed a new multiplex super-assembled ABE(sABE) in rice that showed higher base-editing efficiency than previously developed ABEs. We also designed a new type of nuclear localization signal(NLS) comprising a FLAG epitope tag with four copies of a codon-optimized NLS(F4NLS^(r2)) to generate another ABE named F4NLS-sABE. This new NLS increased editing efficiency or edited additional A at several target sites. A new multiplex super-assembled CBE(sCBE) and F4NLS^(r2) involved F4NLS-sCBE were also created using the same strategy. F4NLS-sCBE was proven to be much more efficient than sCBE in rice. These optimized base editors will serve as powerful genome-editing tools for basic research or molecular breeding in rice and will provide a reference for the development of superior editing tools for other plants or animals.
基金supported by the Beijing Scholars Program[BSP041]。
文摘Base editing, as an expanded clustered regularly interspaced short palindromic repeats(CRISPR)-Cas genome editing strategy, permits precise and irreversible nucleotide conversion. SaKKH, an efficient variant of a Cas9 ortholog from Staphylococcus aureus(SaCas9), is important in genome editing because it can edit sites with HHHAAT protospacer adjacent motif(PAM) that the canonical Streptococcus pyogenes Cas9(SpCas9) or its variants(e.g. xCas9, Cas9-NG) cannot. However, several technical parameters of SaKKH involved base editors have not been well defined and this uncertainty limits their application. We developed an effective multiplex cytosine base editor(SaKKHn-pBE) and showed that it recognized NNARRT, NNCRRT, NNGRGT, and NNTRGT PAMs. Based on 27 targets tested, we defined technical parameters of SaKKHn-pBE including the editing window, the preferred sequence context, and the mutation type. The editing efficiency was further improved by modification of the SaKKH sgRNA. These advances can be applied in future research and molecular breeding in rice and other plants.
文摘This study was designed to summarize the key points of surgical cooperation involving penetrating corneal transplantation combined with implantation of keratoprosthesis. Preoperative preparation and intraoperative procedures were fully implemented to ensure cooperation with the physicians,.to observe the the severity of the disease, and to guarantee the success of the surgery.
基金Major Research Plan of the National Natural Science Foundation of China,Grant/Award Numbers:92166206,92366302Science and Technology Projects of Hunan Province,Grant/Award Number:2024JJ6051。
文摘Metallised film capacitors(MFCs)are renowned for their unique self-healing(SH)properties,which bestow them with exceptional reliability and stability in the face of intense electric fields,high voltages,and pulse power applications.Nonetheless,the exploration of SH characteristics concerning single-layer dielectric film remains insufficient for advancing MFC reliability evaluation.To establish the theoretical correlation of SH characteristics from the device to the film in the MFCs,this work developed a simulation model to analyse the SH dynamic behaviour in the MFCs.The effects of coupling capacitors,arc resistance and insulation resistance on the macroscopic characteristics(voltage drop and pulse current)are focused during the SH process in MFCs.The results indicate that SH is primarily associated with the voltage drop duration rather than the sampling current.Consequently,the SH process in MFC is characterised as an abrupt decrease in voltage to its minimum value.This refinement enhances the SH energy dissipation model of MFC.The quantified relationship between the macroscopic characteristics and microstructure evolution(polypropylene decomposition and aluminium electrode vaporisation)is established in MFCs under diverse SH energy levels.As SH energy and duration increase,the proportion of energy attributed to polypropylene decomposition increases,resulting in multi-layer ablation and adhesion within the metallised film and a pronounced deterioration in MFC electrical performance.The examination of macro-micro perspectives sheds new light on the intricate mechanisms governing the SH behaviour in MFCs,offering valuable insights for the advancement of their design,reliability evaluation,and performance optimisation in diverse electrical applications.
基金This work was supported by Beijing Academy of Agriculture&Forestry Scien ces,Beijing,ChinaThe funding in eluded Innovative Team Con-struction Project of BAAFS(JNKYT201603)the Beijing Scholars Program(BSP041).
文摘The development of CRISPR/Cas9-mediated base editing has made genomic modification more efficient. However, selection of genetically modified cells from millions of treated cells, especially plant cells, is still challenging. In this study, an efficient surrogate reporter system based on a defective hygromycin resistance gene was established in rice to enrich base-edited cells. After step-by-step optimization, the Discriminated sgRNAs-based SurroGate system (DisSUGs) was established by artificially differentiating the editing abilities of a wild-type single guide RNA (sgRNA) targeting the surrogate reporter gene and an enhanced sgRNA targeting endogenous sites. The DisSUGs enhanced the efficiency of screening base-edited cells by 3- to 5-fold for a PmCDA1-based cytosine-to-tyrosine base editor (PCBE), and 2.5- to 6.5-fold for an adenine base editor (ABE) at endogenous targets. These targets showed editing efficiencies of <25% in the conventional systems. The DisSUGs greatly enhanced the frequency of homozygous substitutions and expanded the activity window slightly for both a PCBE and an ABE. Analyses of the total number of single-nucleotide variants from whole-genome sequencing revealed that, compared with the no-enrichment PCBE strategy, the DisSUGs did not alter the frequency of genome-wide sgRNA-independent off-target mutations, but slightly increased the frequency of target-dependent off-target mutations. Collectively, the DisSUGs developed in this study greatly enhances the efficiency of screening plant base-edited cells and will be a useful system in future applications.
文摘The 2050 carbon-neutral vision spawns a novel energy structure revolution,and the construction of the future energy structure is based on equipment innovation.Insulating material,as the core of electrical power equipment and electrified transportation asset,faces unprecedented challenges and opportunities.The goal of carbon neutral and the urgent need for innovation in electric power equipment and electrification assets are first discussed.The engineering challenges constrained by the insulation system in future electric power equipment/devices and electrified transportation assets are investigated.Insulating materials,including intelligent insulating material,high thermal conductivity insulating material,high energy storage density insulating material,extreme environment resistant insulating material,and environmental-friendly insulating material,are cat-egorised with their scientific issues,opportunities and challenges under the goal of carbon neutrality being discussed.In the context of carbon neutrality,not only improves the understanding of the insulation problems from a macro level,that is,electrical power equipment and electrified transportation asset,but also offers opportunities,remaining issues and challenges from the insulating material level.It is hoped that this paper en-visions the challenges regarding design and reliability of insulations in electrical equipment and electric vehicles in the context of policies towards carbon neutrality rules.The authors also hope that this paper can be helpful in future development and research of novel insulating materials,which promote the realisation of the carbon-neutral vision.
基金Major Research Plan of the National Natural Science Foundation of China,Grant/Award Number:92166206Fundamental Research Funds for the Central Universities,Grant/Award Number:2022CDJQY-014Ministry of Education of China through the 111 project,Grant/Award Number:BP0820005。
文摘Metallised polypropylene film capacitors(MPPFCs)are widely used in power electronics and are generally degraded by elevated temperatures.This work aims to determine the relationships between the structural changes of MPPFC and the microstructural variations of the PP film during the thermal ageing of MPPFC at 100℃ for 38 days.The capacitance of MPPFC has a slight decrease during thermal ageing.However,the breakdown voltage of the MPPFC decreases by 39.4%by the ageing.The partial discharge(PD)number of MPPFC increases linearly with ageing time.The tear-down analysis of the MPPFC reveals that the molecular structure of the PP film has not been altered but has led to molecular chain scission and the generation of some polar fragments/groups.Meanwhile,the relative permittivity of the PP films rises as the ageing time increases.Moreover,thermal ageing causes the conversion of aluminum to alumina in the metallised electrode,which is hydrophilic for polar groups and leads to an adhesion effect between the metallised electrodes and the PP film.Contact angle measurements prove that the surface hydrophilicity of the PP sample increased after thermal ageing.Therefore,the PD/breakdown voltage in the MPPFC increases/decreases due to the uneven adhesion of the metallised PP film.
基金This work was supported by Beijing Academy of Agriculture&Forestry SciencesThe funding included Beijing Municipal Natural Science Foundation(6204041)the Beijing Scholars Program(BSP041).
文摘Dear Editor,Base editors(BEs),including cytosine base editor(CBE)and adenine base editor(ABE),have been widely used to generate irreversible nucleotide substitution in plants and animals.However,their wide applications are largely hindered by the strict NG protospacer adjacent motif(PAM)sequences recognized by Streptococcus pyogenes Cas9(SpCas9)and its engineered variants,such as SpCas9-NG and xCas9(Hua et al.,2019;Ren et al.,2019;Wu et al.,2019;Zhong et al.,2019;Zhang et al.,2020).Most recently,it was reported that three new SpCas9 variants,SpCas9-NRRH,SpCas9-NRTH,and SpCas9-NRCH,could recognize non-G PAMs(NRNH,where R is A or G and H is A,C,or T)in human cells(Miller et al.,2020).Meanwhile,SPRY,another new SpCas9 variant,was developed to greatly expand the editing scope of BEs to nearly PAMless(Walton et al.,2020).In this study,we generated a series of efficient BE toolkits and almost achieved C-to-T mutation without PAM restriction except for NTG PAM,and largely expanded A-to-G mutation scope in stable transformed rice,providing a reference for application in other plants.
基金National Natural Science Foundation of China,Grant/Award Number:92166206Fundamental Research Funds for the Central Universities,Grant/Award Number:2022CDJQY‐014111 Project of the Ministry of Education of China,Grant/Award Number:BP0820005。
文摘The flashover strength of epoxy(EP)insulations in the High voltage direct current applications of future energy grids can be improved by tailoring their surface condition.This work aims to improve the DC surface flashover characteristics of EP after being treated with sandpaper of different gradings.Samples with virgin EP and homogenously modified EP considering varying surface roughness(R_(a)=0.54,3.16,5.24,and 8.35μm)are prepared.Different experimental characterisations,such as water contact angle,surface intrinsic conductivity,surface voltages,flashover strength,and trap distributions are conducted and evaluated to analyse the difference between virgin and treated EP.Moreover,based on the obtained experimental results of homogenously treated EP and theoretical analysis,the concept of surface functionally graded materials(SFGMs)is put forward.The flashover voltages of homogenously treated EP are augmented significantly compared to virgin EP regardless of the voltage polarity and enhanced by enhancing the surface roughness.The sample T_(Model‐C) with SFGM design shows a 45.02%and 43.75%improvement in the negative and positive flashover voltages than that of the virgin EP.In the end,COMSOL simulations are conducted to justify the experimental findings and to analyse the difference between virgin and modified samples in terms of electric field distribution.
基金National Natural Science Foundation of China,Grant/Award Number:51425702Ministry of Education of China,Grant/Award Number:B08036National Basic Research Program,Grant/Award Number:2015CB251003。
文摘In this work,the boron nitride(BN)nanosheets were dispersed in natural esters to fabricate the dielectric nanofluid.Microstructures and chemical compositions of the nanosized BN are determined.The stability,viscosity,and thermal conductivity of the BN nanofluid,were obtained.And the dissipation factor,electrical conductivity,and relative permittivity of the BN nanofluid,were measured.The ion mobilities and migrating times of the nanofluid were measured under different volumetric fractions of BN nanosheets and temperatures.Results show that the electrical conductivity and dissipation factor of the nanofluid decreased by 54%and 48%with the addition of only 0.1%of BN nano-sheets under 110°C.Both the half-reduced carrier mobility of the nanofluid and the declined ion concentration by blocking of BN nanosheet contributed to the exponentially reduced electrical conductivity and enhanced dielectric performances of the BN nano-fluid.The suppression coefficient k is proposed to quantitatively describe the hinder effect of ion migration in nanofluids by 2D BN nanosheet.Results provide a strategy to design and develop advanced nanofluids with low-dielectric loss by aids of surface adsorption of ion and steric hindrance of 2D nanosheets.
