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Microstructure formation mechanism of catalyst layer and its effect on fuel cell performance:Effect of dispersion medium composition

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Journal of Energy Chemistry 2022年第10期31卷 588-598,I0015页

作者： Hong Ren Xiangchao Meng Yongli Lin Zhigang Shao Fuel Cell System and Engineering Laboratory Key Laboratory of Fuel Cells&Hybrid Power SourcesDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina University of Chinese Academy of Sciences Beijing 100049China

The design of the catalyst layer(CL)offers a feasible way to realize the commercialization of proton exchange membrane fuel cells(PEMFCs).An in-depth understanding of catalyst inks is critical to achieving the optimal CL structure and cell performance.In this work,the effects of the solvent evaporation process during ink drying on the formation of the CL microstructure are particularly considered to reveal the structure-property correlations among the catalyst ink,drying process,CL microstructure and fuel cell performance.An increase in the alcohol content of the catalyst ink increases the amount of free ionomers while allowing the ionomer backbone to be more stretched in the dispersion medium.The higher alcohol content contributes to rapid solvent evaporation and thus inhibits the formation of coffee rings;as a result,a more developed ionomer network with a denser pore structure is obtained.Therefore,the alcohol-rich electrode exhibits better proton conduction capability,but higher oxygen transport resistance.For complex fuel cell operating conditions,a catalyst ink formulation with 50 wt%alcohol content is preferred due to its proper ionomer and pore size distribution,providing satisfactory fuel cell performance.

关键词： Proton exchange membrane Fuel cell Ink composition Ionomer distribution Pore structure Ink drying process

Diagnosing SST Error Growth during ENSO Developing Phase in the BCC_CSM1.1(m) Prediction System

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Advances in Atmospheric Sciences 2022年第3期39卷 427-442页

作者： Ben TIAN hong-Li ren Laboratory for Climate Studies&CMA-NJU Joint Laboratory for Climate Prediction Studies National Climate CenterChina Meteorological AdministrationBeijing 100081China State Key Laboratory of Severe Weather Institute of Tibetan Plateau&Polar MeteorologyChinese Academy of Meteorological SciencesBeijing 100081China Department of Atmospheric Science School of Environmental StudiesChina University of GeoscienceWuhan 430074China

In this study, the predictability of the El Nino-South Oscillation(ENSO) in an operational prediction model from the perspective of initial errors is diagnosed using the seasonal hindcasts of the Beijing Climate Center System Model,BCC;SM1.1(m). Forecast skills during the different ENSO phases are analyzed and it is shown that the ENSO forecasts appear to be more challenging during the developing phase, compared to the decay phase. During ENSO development, the SST prediction errors are significantly negative and cover a large area in the central and eastern tropical Pacific, thus limiting the model skill in predicting the intensity of El Nino. The large-scale SST errors, at their early stage, are generated gradually in terms of negative anomalies in the subsurface ocean temperature over the central-western equatorial Pacific,featuring an error evolutionary process similar to that of El Nino decay and the transition to the La Nina growth phase.Meanwhile, for short lead-time ENSO predictions, the initial wind errors begin to play an increasing role, particularly in linking with the subsurface heat content errors in the central-western Pacific. By comparing the multiple samples of initial fields in the model, it is clearly found that poor SST predictions of the Nino-3.4 region are largely due to contributions of the initial errors in certain specific locations in the tropical Pacific. This demonstrates that those sensitive areas for initial fields in ENSO prediction are fairly consistent in both previous ideal experiments and our operational predictions,indicating the need for targeted observations to further improve operational forecasts of ENSO.

关键词： ENSO prediction initial errors error evolution SST

Low-level viremia in nucleoside analog-treated chronic hepatitis B patients

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Chinese Medical Journal 2021年第23期134卷 2810-2817页

作者： Qian Zhang Da-Chuan Cai Peng Hu Hong Ren Department of Infectious Diseases Institute for Viral HepatitisThe Key Laboratory of Molecular Biology for Infectious DiseasesChinese Ministry of EducationThe Second Affiliated Hospital of Chongqing Medical UniversityChongqing 400010China Department of Infectious Diseases Guizhou Provincial People’s HospitalGuiyangGuizhou 550001China.

Low-level viremia(LLV)was defined as persistent or intermittent episodes of detectable hepatitis B virus(HBV)DNA(<2000 IU/mL,detection limit of 10 IU/mL)after 48 weeks of antiviral treatment.Effective antiviral therapies for chronic hepatitis B(CHB)patients,such as entecavir(ETV),tenofovir disoproxil fumarate(TDF),and tenofovir alafenamide(TAF),have been shown to inhibit the replication of HBV DNA and prevent liver-related complications.However,even with long-term antiviral therapy,there are still a number of patients with persistent or intermittent LLV.At present,the research on LLV to address whether adversely affect the clinical outcome is limited,and the follow-up treatment for these patients is open to question.At the same time,the mechanism of LLV is not clear.In this review,we summarize the incidence of LLV,the association between LLV and long-term outcomes,possible mechanisms,and management strategies in these patient populations.

关键词： Chronic hepatitis B Nucleoside/nucleotide analog treatment Low-level viremia Long-term outcomes

Performance analysis of active RIS-aided multi-pair full-duplex communications with spatial correlation and imperfect CSI

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Science China(Information Sciences) 2023年第9期66卷 259-273页

作者： Zhangjie PENG Xueya LIU Xue LIU Cunhua PAN Xianzhe CHEN Hong Ren College of Information Mechanical and Electrical Engineering Shanghai Normal University National Mobile Communications Research Laboratory Southeast University

This paper investigates a multi-pair full-duplex(FD) communication system aided by an active reconfigurable intelligent surface(RIS) with spatial correlation and imperfect channel state information(CSI).We apply the linear minimum mean square error(LMMSE) method to estimate the cascaded user-RIS-user channel. The approximation for the sum achievable rate(ACR) is derived in closed form over correlated Rician fading channels. To provide insights in a poor-scattering environment, the sum ACR limits are also given when the Rician factors grow infinite. Subsequently, a method based on a genetic algorithm(GA)is designed for the sum ACR maximization considering the cases of continuous and discrete phase shifts.Simulation results validate the derived results, and present that the sum ACRs in the active RIS system are higher than the passive counterparts with the same power consumption, which indicates the superiority of the active RIS in overcoming the “multiplicative fading” effect.

关键词： RIS active RIS FD communication spatial correlation imperfect CSI

Skillful prediction of winter Arctic Oscillation from previous summer in a linear empirical model

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Science China Earth Sciences 2021年第1期64卷 27-36页

作者： hong-Li ren Yu NIE State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China Laboratory for Climate Studies&CMA-NJU Joint Laboratory for Climate Prediction Studies National Climate CenterChina Meteorological AdministrationBeijing 100081China Department of Atmospheric Science School of Environmental StudiesChina University of GeoscienceWuhan 430074China

The winter Arctic Oscillation(WAO),as a primary atmospheric variability mode in the Northern Hemisphere,plays a key role in influencing mid-high-latitude climate variations.However,current dynamical seasonal forecasting systems have limited skills in predicting WAO with lead time longer than two months.In this study,we design a linear empirical model using two effective precursors from anomalies of the Arctic sea ice concentration(SIC)and the tropical sea surface temperature(SST)initiated in preceding late summer(August)which are both significantly correlated with WAO in recent four decades.This model can provide a skillful prediction of WAO at about half-year lead started from previous summer and perform much better than the dynamical models.Such a significantly prolonged lead time is owed to the stable precursor signals extracted from the SIC and SST anomalies over specific areas,which can persist from previous August and be further enhanced through autumn months.Validation results show that this model can produce a 20-year independent-validated prediction skill of 0.45 for 1999–2018 and a 39-year cross-validated skill of 0.67 for 1980–2018,providing a potentially effective tool for earlier predictions of winter climate variations at mid-high latitudes.

关键词： Arctic Oscillation(AO) Winter AO prediction Sea ice concentration Sea surface temperature Linear empirical model

Electric-Field-Treated Ni/Co_(3)O_(4) Film as High-Performance Bifunctional Electrocatalysts for Efficient Overall Water Splitting

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Nano-Micro Letters 2022年第9期14卷 160-173页

作者： Junming Li Jun Li Jun ren hong hong Dongxue Liu Lizhe Liu Dunhui Wang National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced MicrostructuresJiangsu Provincial Key Laboratory for NanotechnologySchool of PhysicsNanjing UniversityNanjing 210093People’s Republic of China Hangzhou Dianzi University Hangzhou 310018People’s Republic of China

Rational design of bifunctional electrocatalysts for oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)with excellent activity and stability is of great significance,since overall water splitting is a promising technology for sustainable conversion of clean energy.However,most electrocatalysts do not simultaneously possess optimal HER/OER activities and their electrical conductivities are intrinsically low,which limit the development of overall water splitting.In this paper,a strategy of electric field treatment is proposed and applied to Ni/Co_(3)O_(4) film to develop a novel bifunctional electrocatalyst.After treated by electric field,the conductive channels consisting of oxygen vacancies are formed in the Co_(3)O_(4) film,which remarkably reduces the resistance of the system by almost 2×10^(4) times.Meanwhile,the surface Ni metal electrode is partially oxidized to nickel oxide,which enhances the catalytic activity.The electric-field-treated Ni/Co_(3)O_(4) material exhibits super outstanding performance of HER,OER,and overall water splitting,and the catalytic activity is significantly superior to the state-of-the-art noble metal catalysts(Pt/C,RuO_(2),and RuO_(2)‖Pt/C couple).This work provides an effective and feasible method for the development of novel and efficient bifunctional electrocatalyst,which is also promising for wide use in the field of catalysis.

关键词： Bifunctional electrocatalyst Overall water splitting Co_(3)O_(4)film Oxygen vacancies Electric field

Revisiting the mechanisms of mid-Tertiary uplift of the NE Tibetan Plateau

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National Science Review 2023年第4期10卷 169-190页

作者： hong-hong Wei Guo-Li Wu Lin Ding Long-Gang Fan Lin Li Qing-ren Meng State Key Laboratory of Tibetan Plateau Earth System Environment and Resources (TPESER) Institute of Tibetan Plateau Research Chinese Academy of Sciences Institute of Geomechanics Chinese Academy of Geological Sciences State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Department of Geosciences University of Arizona University of Chinese Academy of Sciences

Contrasting views exist on timing and mechanisms of Tertiary crustal uplift in the NE Tibetan Plateau based on different approaches, with many models atributing surface uplift to crustal shortening. We carry out a comprehensive investigation of mid-Tertiary stratigraphy, sedimentology, and volcanism in the West Qinling, Hoh Xil and Qaidam basin, and the results challenge previous views. It was held that the discordance between Oligocene and Miocene strata is an angular unconformity in the West Qinling, but our field observations show that it is actually a disconformity, indicative of vertical crustal uplifting rather than crustal shortening at the Oligocene to Miocene transition. Widespread occurrence of synsedimentary normal faults in mid-Tertiary successions implicates supracrustal stretching. Miocene potassic–ultrapassic and mafic–ultramafic volcanics in the Hoh Xil and West Qinling suggest a crucial role of deep thermomechanical processes in generating crust-and mantle-sourced magmatism. Also noticeable are the continuity of mid-Tertiary successions and absence of volcanics in the Qaidam basin. Based on a holistic assessment of stratigraphic–sedimentary processes, volcanic petrogenesis, and spatial variations of lithospheric thicknesses, we speculate that small-sale mantle convection might have been operating beneath northeast Tibet in the mid-Tertiary. It is assumed that northward asthenospheric flow was impeded by thicker cratonic lithosphere of the Qaidam and Alxa blocks, thereby leading to edge convection. The edge-driven convection could bring about surface uplift, induce supracrustal stretching, and trigger vigorous volcanism in the Hoh Xil and West Qinling in the mid-Tertiary period. This mechanism satisfactorily explains many key geologic phenomena that are hardly reconciled by previous models.

关键词： NE Tibetan Plateau mid-Tertiary unconformity volcanism edge convection

Acid tolerance of lactate-utilizing bacteria of the order Bacteroidales contributes to prevention of ruminal acidosis in goats adapted to a high-concentrate diet

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Animal Nutrition 2023年第3期14卷 130-140页

作者： Zhongyan Lu Lingmeng Kong Shenhao ren Jorg RAschenbach hong Shen Key Lab of Animal Physiology and Biochemistry College of Veterinary MedicineNanjing Agricultural UniversityNanjingJiangsuChina College of Life Science Nanjing Agricultural UniversityNanjingJiangsuChina Institute of Veterinary Physiology Freie Universitat BerlinBerlinGermany Bioinformatics Center Academy for Advanced Interdisciplinary StudiesNanjing Agricultural UniversityNanjingJiangsuChina

The rapid accumulation of organic acids,particularly lactate,has been suggested as the main cause of ruminal acidosis(RA)for ruminants fed high-concentrate diets.Previous research has shown that a gradual shift from low-to high-concentrate diets within 4 to 5 weeks effectively reduces the risk for RA.However,the mechanisms remain unknown.In this study,20 goats were randomly allocated into four groups(n=5)and fed with a diet containing a weekly increasing concentrate portion of 20%,40%,60%,and 80%over 28 d.At d 7,14,21,and 28,one group(named C20,C40,C60,and C80 according to the last concentrate level that they received)was killed and the ruminal microbiome was collected.Ruminal acidosis was not detected in any of the goats during the experiment.Nonetheless,ruminal pH dropped sharply from 6.2 to 5.7(P<0.05)when dietary concentrate increased from 40%to 60%.A combined metagenome and metatranscriptome sequencing approach identified that this was linked to a sharp decrease in the abundance and expression of genes encoding nicotinamide adenine dinucleotide(NAD)-dependent lactate dehydrogenase(nLDH),catalyzing the enzymatic conversion of pyruvate to lactate(P<0.01),whereas the expression of two genes encoding NAD-independent lactate dehydrogenase(iLDH),catalyzing lactate oxidation to pyruvate,showed no significant concomitant change.Abundance and expression alterations for nLDH-and iLDH-encoding genes were attributable to bacteria from Clostridiales and Bacteroidales,respectively.By analyzing the gene profiles of 9 metagenome bins(MAG)with nLDH-encoding genes and 5 MAG with iLDH-encoding genes,we identified primary and secondary active transporters as being the major types of sugar transporter for lactate-producing bacteria(LPB)and lactate-utilizing bacteria(LUB),respectively.Furthermore,more adenosine triphosphate was required for the phosphorylation of sugars to initiate their catabolic pathways in LPB compared to LUB.Thus,the low dependence of sugar transport systems and catabolic pathways on primary energy sources su

关键词： Ruminal microbiome Ruminal acidosis Acid tolerance Lactate metabolism

Passenger emergency evacuation from bus carriage:Results from realistic data and modeling simulations

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Journal of Management Science and Engineering 2022年第4期7卷 530-549页

作者： Hai-hong Xu ren-Yong Guo School of Economics and Management Beihang UniversityBeijing10191China Key Laboratory of Complex System Analysis and Management Decision Ministry of EducationBejing100191China

One of critical challenges in the development of pedestrian models is the lack of relevant data under emergency conditions.In this paper,we reveal several behavior characteristics of passenger emergency evacuation from a burning bus carriage,by observing and analyzing a video recording,attempting to close the gap between practical observation and theoretical modeling.The analysis results show that there are considerable differences between real emergency evacuation and experimental normal evacuation with respect to the cumulative flows,flows,and time gap distributions.Additionally,the behavior of falling-down,which contributes to the formation of movable obstacles,interrupts the continuity of the evacuation process.Then,we incorporate these behavioral characteristics into a microscopic pedestrian model with a fine lattice space representation.The simulation results indicate that the escape is slowed down by the falling behavior,as well as by the luggage-carrying behavior.

关键词： Emergency evacuation Bus passenger Egress behavior Movable obstacle Microscopic pedestrian model