Structure,Property,and Performance of Catalyst Layers in Proton Exchange Membrane Fuel Cells

Catalyst layer(CL)is the core component of proton exchange membrane(PEM)fuel cells,which determines the performance,durability,and cost.However,difficulties remain for a thorough understanding of the CLs’inhomogeneous structure,and its impact on the physicochemical and electrochemical properties,operating performance,and durability.The inhomogeneous structure of the CLs is formed during the manufacturing process,which is sensitive to the associated materials,composi-tion,fabrication methods,procedures,and conditions.The state-of-the-art visualization and characterization techniques are crucial to examine the CL structure.The structure-dependent physicochemical and electrochemical properties are then thoroughly scrutinized in terms of fundamental concepts,theories,and recent progress in advanced experimental techniques.The relation between the CL structure and the associated effective properties is also examined based on experimental and theoretical findings.Recent studies indicated that the CL inhomogeneous structure also strongly affects the performance and degradation of the whole fuel cell,and thus,the interconnection between the fuel cell performance,failure modes,and CL structure is comprehensively reviewed.An analytical model is established to understand the effect of the CL structure on the effective properties,performance,and durability of the PEM fuel cells.Finally,the challenges and prospects of the CL structure-associated studies are highlighted for the development of high-performing PEM fuel cells.

Red list assessments of Chinese higher plants

Based on the two most recent assessments of Chinese higher plants in 2013 and 2020,of 34,450 and 39,330 species,respectively,we analysed the threatened status of Chinese higher plants.In 2020,around 4,088(10.39%)of the assessed species in China are threatened,2,875(7.31%)Near Threatened,27,593(70.16%)not currently threatened and categorised as Least Concern and 4,752(12.08%)categorised as Data Deficient.While in 2013,3,767(10.93%)of the assessed higher plants in China are threatened,2,723(7.90%)Near Threatened,24,296(70.53%)Least Concern and 3,612(10.48%)Data Deficient.Estimates of the Red List Index in the two years show different patterns when using different weighting methods with the equal steps weighting method showing a slight decrease(0.91675-0.91495)and the extinction risk weighting method showing a slight increase(0.98792-0.98797).We inferred that China's threatened plant species were likely/relatively effectively protected.However,attention should also be given to the non-threatened species in the future as an additional strategy for their conservation,to maintain their non-threatened status.

A Real-world Prospective Study of Mother-to-child Transmission of HBV in China Using a Mobile Health Application (Shield 01)

Background and Aims:The World Health Organization(WHO)Western Pacific Region set a target of eliminating mother-to-child transmission(MTCT)of hepatitis B virus(HBV)by 2030.To assess the feasibility of this target in China,we carried out an epidemiological study to investigate the status quo of MTCT in the real-world setting.Methods:One thousand and eight hepatitis B surface antigen-positive preg-nant women were enrolled at 10 hospitals.Immunoprophy-laxis was administered to infants.In addition,mothers with HBV DNA level>2,000,000 IU/mL were advised to initiate antiviral therapy during late pregnancy.A health application called SHIELD was used to manage the study.Results:Nine hundred and five of the enrolled mothers,with 924 infants,completed the follow-up.Birth-dose hepatitis B vaccine and hepatitis B immunoglobulin were received by 99.7%and 99.7%of infants,respectively,within 24 h after birth.There ;were 446 mothers who received antiviral therapy,including 72.3%of the mothers with HBV DNA level>2,000,000 IU/mL and 21.0%of the mothers with HBV DNA level<2,000,000 IU/mL.Eight infants were infected with HBV.The overall rate of MTCT was 0.9%.Birth defects were rare(0.5%among in-fants with maternal antiviral exposure versus 0.7%among infants without exposure;p=1.00).Conclusions:The MTCT rate was lower than the WHO Western Pacific Region elimina-tion MTCT target in this real-world study,indicating that a comprehensive management composed of immunoprophy-laxis to infants and antiviral prophylaxis to mothers may be a feasible strategy to achieve the 2030 WHO elimination goal.

Mode demultiplexing hybrids for mode-division multiplexing coherent receivers

We propose a mode demultiplexing hybrid(MDH) that integrates mode demultiplexing, local oscillator power splitting, and optical 90-deg mixing using multi-plane light conversion(MPLC). We demonstrate the realization of a three-mode MDH using four phase plates, one more than what is required for an MPLC-based mode demultiplexer, via numerical simulations. The performance of the three-mode MDH is comparable to that of commercial single-mode 90-deg hybrids. This multiple-functionality device enables simplification of the coherent optical front end of mode-division multiplexing receivers.

Few-mode fibre-optic microwave photonic links

The fibre-optic microwave photonic link has become one of the basic building blocks for microwave photonics.Increasing the optical power at the receiver is the best way to improve all link performance metrics including gain,noise figure and dynamic range.Even though lasers can produce and photodetectors can receive optical powers on the order of a Watt or more,the power-handling capability of optical fibres is orders-of-magnitude lower.In this paper,we propose and demonstrate the use of few-mode fibres to bridge this power-handling gap,exploiting their unique features of small acousto-optic effective area,large effective areas of optical modes,as well as orthogonality and walk-off among spatial modes.Using specially designed few-mode fibres,we demonstrate order-of-magnitude improvements in link performances for single-channel and multiplexed transmission.This work represents the first step in few-mode microwave photonics.The spatial degrees of freedom can also offer other functionalities such as large,tunable delays based on modal dispersion and wavelength-independent lossless signal combining,which are indispensable in microwave photonics.

Regional difference and influencing factors of the green development level in the urban agglomeration in the middle reaches of the Yangtze River

The urban agglomeration in the middle reaches of the Yangtze River(UAMRYR)is a key area to promote the central region rise and the green development of the Yangtze River Economic Belt.In this paper,an evaluation index system was comprehensively constructed for the green development level of the UAMRYR from five aspects:resource utilization,green environment,green economy,green life,and support mechanisms.Entropy weight-TOPSIS method and multivariate statistical method,including spatial autocorrelation analysis and geographic detectors,were used to analyze the regional differences and influencing factors of the green development level of the UAMRYR from 2008 to 2018.The results showed that:(1)the overall green development level of the UAMRYR showed a fluctuating upward trend from 2008 to 2018,among which the provincial capital cities such as Wuhan,Changsha,and Nanchang,as well as the cities covered by the Poyang Lake urban agglomeration had relatively higher green development levels.(2)The green development level of the 31 cities in the UAMRYR showed insignificant spatial heterogeneity within the study period.Compared with other areas,the green development levels varied greatly among the regions of the Wuhan metropolitan area,which was a typical high-low aggregation type.(3)Green economy,green life,and support mechanisms were the highly influential aspects of the green development of the UAMRYR,and the main influencing factors were the total value added of secondary and tertiary industries,urbanization rate,and fixed asset investment.The explanatory power of the interaction of influencing factors on the green development of the UAMRYR was greater than that of a single factor.This study is intended to provide a reference for the green transformation development and the coordinated development of the“resources-environment-economy”in the UAMRYR.

Applications of weakly-coupled few-mode fibers[Invited]

Space-division multiplexing(SDM)has attracted significant attention in recent years because larger transmission capacity is enabled by more degrees of freedom(DOFs)in few-mode fibers(FMFs)compared with singlemode fibers(SMFs).To transmit independent information on spatial modes without or with minor digital signal processing(DSP),weakly-coupled FMFs are preferred in various applications.Several cases with different use of spatial DOFs in weakly-coupled FMFs are demonstrated in this work,including single-mode or mode-groupmultiplexed transmission,and spatial DOFs combined with time or frequency DOF to improve the system performance.

Controlled Synthesis of Carbon-Supported Pt-Based Electrocatalysts for Proton Exchange Membrane Fuel Cells

Proton exchange membrane fuel cells are playing an increasing role in postpandemic economic recovery and climate action plans.However,their performance,cost,and durability are significantly related to Pt-based electrocatalysts,hampering their large-scale commercial application.Hence,considerable efforts have been devoted to improving the activity and durability of Pt-based electrocatalysts by controlled synthesis in recent years as an effective method for decreasing Pt use,and consequently,the cost.Therefore,this review article focuses on the synthesis processes of carbon-supported Pt-based electrocatalysts,which significantly affect the nanoparticle size,shape,and dispersion on supports and thus the activity and durability of the prepared electrocatalysts.The reviewed processes include(i)the functionalization of a commercial carbon support for enhanced catalyst-support interaction and additional catalytic effects,(ii)the methods for loading Pt-based electrocatalysts onto a carbon support that impact the manufacturing costs of electrocatalysts,(iii)the preparation of spheri-cal and nonspherical Pt-based electrocatalysts(polyhedrons,nanocages,nanoframes,one-and two-dimensional nanostruc-tures),and(iv)the postsynthesis treatments of supported electrocatalysts.The influences of the supports,key experimental parameters,and postsynthesis treatments on Pt-based electrocatalysts are scrutinized in detail.Future research directions are outlined,including(i)the full exploitation of the potential functionalization of commercial carbon supports,(ii)scaled-up one-pot synthesis of carbon-supported Pt-based electrocatalysts,and(iii)simplification of postsynthesis treatments.One-pot synthesis in aqueous instead of organic reaction systems and the minimal use of organic ligands are preferred to simplify the synthesis and postsynthesis treatment processes and to promote the mass production of commercial carbon-supported Pt-based electrocatalysts.

Clinical analysis of the characteristics of patients diagnosed with hemolytic anemia induced by hepatitis E viral infection

Background:The extrahepatic manifestations of hepatitis E virus(HEV)infection include hemolytic anemia.However,the clinical characteristics of HEV-induced hemolytic anemia have been only sporadically reported in case reports,and there is a scarcity of relevant systematic reviews.The aim of the current study was to analyze and summarize the clinical characteristics of patients diagnosed with HEV-induced hemolytic anemia.Methods:This study included 1 patient diagnosed with HEV-induced hemolytic anemia who was admitted to our hospital and 19 additional patients identified through the available literature.Results:Of the 20 patients included in this study,the majorities were from China and India(12 and 6 cases,respectively);furthermore,13 of them were men and 7 were women,with an average age of 35(16–56)years.The highest total bilirubin level was 646(452–913)μmol/L,highest alanine aminotransferase level was 1335(708–2798)IU/L,and lowest hemoglobin level was 6.0
2.0 g/dL.Additionally,10 patients(50.0%,10/20)underwent the glucose-6-phosphate dehydrogenase(G6PD)activity test,and all of them were diagnosed with G6PD deficiency(100.0%,10/10).Finally,18 patients(90.0%)recovered and 2 died(10.0%)after treatment.Conclusions:Most of the patients with HEV-induced hemolytic anemia recovered with treatment.Acute HEV infection that causes hemolytic anemia is strongly associated with the G6PD status of the patients.