Silicon(Si)has emerged as a potent anode material for lithium-ion batteries(LIBs),but faces challenges like low electrical conductivity and significant volume changes during lithiation/delithiation,leading to material...Silicon(Si)has emerged as a potent anode material for lithium-ion batteries(LIBs),but faces challenges like low electrical conductivity and significant volume changes during lithiation/delithiation,leading to material pulverization and capacity degradation.Recent research on nanostructured Si aims to mitigate volume expansion and enhance electrochemical performance,yet still grapples with issues like pulverization,unstable solid electrolyte interface(SEI)growth,and interparticle resistance.This review delves into innovative strategies for optimizing Si anodes’electrochemical performance via structural engineering,focusing on the synthesis of Si/C composites,engineering multidimensional nanostructures,and applying non-carbonaceous coatings.Forming a stable SEI is vital to prevent electrolyte decomposition and enhance Li^(+)transport,thereby stabilizing the Si anode interface and boosting cycling Coulombic efficiency.We also examine groundbreaking advancements such as self-healing polymers and advanced prelithiation methods to improve initial Coulombic efficiency and combat capacity loss.Our review uniquely provides a detailed examination of these strategies in real-world applications,moving beyond theoretical discussions.It offers a critical analysis of these approaches in terms of performance enhancement,scalability,and commercial feasibility.In conclusion,this review presents a comprehensive view and a forward-looking perspective on designing robust,high-performance Si-based anodes the next generation of LIBs.展开更多
Aqueous zinc-ion batteries possess substantial potential for energy storage applications;however,they are hampered by challenges such as dendrite formation and uncontrolled side reactions occurring at the zinc anode.I...Aqueous zinc-ion batteries possess substantial potential for energy storage applications;however,they are hampered by challenges such as dendrite formation and uncontrolled side reactions occurring at the zinc anode.In our investigation,we sought to mitigate these issues through the utilization of in situ zinc complex formation reactions to engineer hydrophobic protective layers on the zinc anode surface.These robust interfacial layers serve as effective barriers,isolating the zinc anode from the electrolyte and active water molecules and thereby preventing hydrogen evolution and the generation of undesirable byproducts.Additionally,the presence of numerous zincophilic sites within these protective layers facilitates uniform zinc deposition while concurrently inhibiting dendrite growth.Through comprehensive evaluation of functional anodes featuring diverse functional groups and alkyl chain lengths,we meticulously scrutinized the underlying mechanisms influencing performance variations.This analysis involved precise modulation of interfacial hydrophobicity,rapid Zn^(2+)ion transport,and ordered deposition of Zn^(2+)ions.Notably,the optimized anode,fabricated with octadecylphosphate(OPA),demonstrated exceptional performance characteristics.The Zn//Zn symmetric cell exhibited remarkable longevity,exceeding 4000 h under a current density of 2 mA cm^(-2)and a capacity density of 2 mA h cm^(-2),Furthermore,when integrated with a VOH cathode,the complete cell exhibited superior capacity retention compared to anodes modified with alternative organic molecules.展开更多
We develop a numerical method for the time evolution of Gaussian wave packets on flat-band lattices in the presence of correlated disorder.To achieve this,we introduce a method to generate random on-site energies with...We develop a numerical method for the time evolution of Gaussian wave packets on flat-band lattices in the presence of correlated disorder.To achieve this,we introduce a method to generate random on-site energies with prescribed correlations.We verify this method with a one-dimensional(1D)cross-stitch model,and find good agreement with analytical results obtained from the disorder-dressed evolution equations.This allows us to reproduce previous findings,that disorder can mobilize 1D flat-band states which would otherwise remain localized.As explained by the corresponding disorder-dressed evolution equations,such mobilization requires an asymmetric disorder-induced coupling to dispersive bands,a condition that is generically not fulfilled when the flat-band is resonant with the dispersive bands at a Dirac point-like crossing.We exemplify this with the 1D Lieb lattice.While analytical expressions are not available for the two-dimensional(2D)system due to its complexity,we extend the numerical method to the 2D a–T3 model,and find that the initial flat-band wave packet preserves its localization when a=0,regardless of disorder and intersections.However,when a̸=0,the wave packet shifts in real space.We interpret this as a Berry phase controlled,disorder-induced wave-packet mobilization.In addition,we present density functional theory calculations of candidate materials,specifically Hg1−xCdxTe.The flat-band emerges near the G point(α=0)in the Brillouin zone.展开更多
A new water-soluble heteropolysaccharide with a molecular weight of 15 k Da was isolated from the fruiting bodies of Boletus reticulatus Schaeff.Structural characterization results revealed that B.reticulatus Schaeff ...A new water-soluble heteropolysaccharide with a molecular weight of 15 k Da was isolated from the fruiting bodies of Boletus reticulatus Schaeff.Structural characterization results revealed that B.reticulatus Schaeff polysaccharide(BRS-X)had a backbone of 1,6-linkedα-D-galactose and 1,2,6-linkedα-D-galactose which branches were mainly composed of a terminal 4-linkedβ-D-glucose and the ratio of D-galactose and D-glucose was 5:1.Bioactivity assays indicated that BRS-X displayed a strong proliferative activity in T cells and B cells and promoted the secretion of immunoglobulin G(Ig G),Ig E,Ig D and Ig M.In addition,BRS-X could facilitate the proliferation and phagocytosis of RAW264.7 cells and could significantly inhibit the growth of tumors in S180-bearing mice.The results of transcriptome sequencing analysis illustrated that total 46 genes enriched in MAPK and total 34 genes enriched in PI3 K/Akt signaling pathways in BRS-X group.The protein VEGF and VEGFR expression were significantly reduced under the treatment with BRS-X.These findings provide a scientific basis for the edible and medicinal value of BRS-X.展开更多
With exhaustion of fossil fuels and the deterioration of global environment,widespread and intensive researches have been concentrated on clean and sustainable alternative energy sources,such as metal-air batteries[1]...With exhaustion of fossil fuels and the deterioration of global environment,widespread and intensive researches have been concentrated on clean and sustainable alternative energy sources,such as metal-air batteries[1],fuel cells[2]and water splitting devices[3].Electrocatalytic oxidation of water to O2(oxygen evolution reaction,OER)is a vital chemical process involved in energy storage and conversion from renewable sources in form of molecular fuels such as H2 via water electrolysis,which has attracted a great amount of research efforts in the past few years[4,5].Nowadays,RuO2 and IrO2 are widely used as typical excellent OER electrocatalysts.However,their high-cost and scarce nature restricts the broadly commercial application of those materials[6,7].Hence,there is an urgent demand to develop low cost,highly efficient,and superb stable OER catalysts.展开更多
The problem addressed in this paper concerns the extension of widely linear beamforming to the wideband case,developing a wide-focused linear beamformer for the extraction of a wideband second-order(SO)noncircular sig...The problem addressed in this paper concerns the extension of widely linear beamforming to the wideband case,developing a wide-focused linear beamformer for the extraction of a wideband second-order(SO)noncircular signal-of-interest(SOI)contaminated by uncorrelated interferences and noise.In the proposed beamformer,the beamforming array observation is first focused to adopt a standard linear minimum variance distortionless response(MVDR)framework.The augmented SOI steering vector then is obtained by estimating the SOI noncircularity parameter with the newly proposed oblique projection with an augmented sparse representation scheme.The covariance matrix of the virtual interference,true interference and noise is further reconstructed using the newly presented complementary spatial spectrum technique.The wideband widely linear spatial filtering is finally realized via MVDR like beamforming.The performance of the proposed beamformer is verified by simulation.展开更多
Many rivers originate in high mountainous regions. However, the effects of climate warming on the runoff and water balance in these regions remain unclear due to the lack of observational data from harsh environments,...Many rivers originate in high mountainous regions. However, the effects of climate warming on the runoff and water balance in these regions remain unclear due to the lack of observational data from harsh environments, and the variable influences of climate change on alpine land-cover types with different water balances. Using observations and simulations from Coup Model, water-balance values collected at five alpine land-cover types(steppe, shrub meadow, moist meadow, swamp meadow, and moraine) in a small alpine watershed, the Qilian Mountains in Northwest China, from October 2008 to September 2014, were compared. Measured evapotranspiration, multilayer soil temperatures and water contents, and frozen-depth data were used to validate Coup Model outputs. The results show that elevation is the primary influence on precipitation, evapotranspiration, and runoff coefficients in alpine regions. Land-cover types at higher elevations receive more precipitation and have a larger runoff coefficient. Notably, climate warming not only increases evapotranspiration but also particularly increases the evapotranspiration/precipitation ratio due to an upward shift in the optimum elevation of plant species. These factors lead to decrease runoff coefficients in alpine basins.展开更多
OBJECTIVE To summarize the regular pattern and state oflymph node metastasis of patients with esophageal and cardiaccarcinomas,so as to analyze factors influencing lymph nodemetastasis.METHODS Clinical data collected ...OBJECTIVE To summarize the regular pattern and state oflymph node metastasis of patients with esophageal and cardiaccarcinomas,so as to analyze factors influencing lymph nodemetastasis.METHODS Clinical data collected from 1,526 thoracicesophageal and cardiac carcinoma patients who were admitted inthe Fourth Hospital of Hebei Medical University during a periodfrom January 1996 to December 2004,were randomly selectedand an Access Database of the patient's information was set up.Eight clinico-pathologic factors,including the patient's age,tumorlocation and size,pathological classification,the depth of tumorinvasion,vascular tumor embolus (VTE),the state of surroundingorgan encroachment and the status of tumor residues,wereidentified.A correlation between these factors and metastases wasstatistically analyzed using SPSS13.0 software.RESULTS Lymph node metastatic sites from esophagealcarcinomas included the thoracic and abdominal cavity.Lymphnode metastasis from the superior esophageal carcinomasmainly occurred in the neck and thoracic cavity.There was atwo-way lymph node metastasis in the patients with the middleesophageal carcinoma.The inferior esophageal carcinomas mainlymetastasized to the paraesophageal,paragastric cardia,and leftgastric artery lymph nodes.The rate and degree of the metastasisfrom the inferior esophageal carcinomas were significantly highercompared to those of the superior and the middle esophagealcarcinomas (P<0.0125).The degree of abdominal lymph node metastasis fromcarcinomas of the gastric cardia was significantly higher comparedwith that of esophageal carcinomas.In the group with carcinomaof the gastric cardia,the rate and degree of the lymph nodemetastases in the paragastric cardia and left gastric artery weresignificantly higher compared to the group with esophagealcarcinoma (P<0.05).Paraesophageal lymph node metastasis fromcarcinomas of the gastric cardia in the thoracic cavity frequentlyoccurred,too,and the degree of the metastasis was similar to thatof esophageal carcinoma.There was no significant difference inthe rate and degree of the paraesophageal lymph-node metastasisbetween the group with carcinoma of the gastric cardia comparedto those with esophageal carcinoma (P>0.05).Multifactoriallogistic regression analysis showed that the tumor size,depth oftumor encroachment,VTE,and tumor residues could all bringabout obvious impact on lymph-node metastases (P<0.05).CONCLUSION Lymph node metastasis from superioresophageal carcinomas mainly occurs in the neck and thoraciccavity.The middle esophageal carcinomas presented a two-waylymph-node metastasis (both the upwards and the downwards),and the lymph node metastasis from inferior esophagealcarcinomas mainly occurred in the thoracic and abdominal cavities.The metastases of carcinoma of the gastriccardia were most commonly found in the abdominalcavity,with frequent paraesophageal lymph-nodemetastasis.The sufficient attention should be paidto neck lymph node clearance in cases of esophagealcarcinoma.What is of the greatest concern is theclearance of the left gastric artery lymph nodes,andalso in cases of gastric cardia carcinoma,clearance,the paraesophageal lymph nodes.With an increasein the tumor size and depth of tumor encroachment,and occurrence of VTE and tumor residual cells,therisk of lymph node metastasis is significantly raised (P<0.05).展开更多
With the continuous advancement of China’s infrastructure construction to the west,according to the geographic situation in the southwest region,such as mountainous areas and complex terrain,the road construction pro...With the continuous advancement of China’s infrastructure construction to the west,according to the geographic situation in the southwest region,such as mountainous areas and complex terrain,the road construction process is inevitably accompanied by earth and rock blasting.To improve the quality and safety of the project,this paper addresses the problems of land and rock blasting faced in the construction of mountain road projects,taking the research of rock dynamic mechanics test as the starting point,and using a combination of theoretical analysis and experimental research methods.The specific research content includes the following parts:dynamic impact compression test(SHPB),dynamic splitting tensile test,and stress-strain curve analysis of the test results,which provides the theoretical basis and numerical parameters for the numerical simulation of future engineering blasting.展开更多
Non-precious metal-nitrogen-carbon(MNC)electrocatalysts have gained tremendous attention as promising electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).However,the most applicable s...Non-precious metal-nitrogen-carbon(MNC)electrocatalysts have gained tremendous attention as promising electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).However,the most applicable strategies for the synthesis of MNC materials heavily rely on pyrolysis treatment,which may easily lead to metal aggregation and subsequent degradation of catalytic performance.Herein,we developed a pyrolysis-free strategy for preparing MNC materials,which was demonstrated by achieving ultrathin cobalt-nitrogen-carbon(Co NC)layer with dense atomically dispersed cobalt sites depositing on graphene oxide(GO)via simple treatment of Co salt and GO in formamide.The formamide-derived Co NC layer deposited on GO(termed as f-Co NC/GO)could be controlled in 1-2 nm thick.Remarkably,the f-CoNC/GO composite without pyrolysis exhibited excellent bifunctional performance toward ORR and OER,which was attributed to the dense atomically dispersed Co-Nxsites and improved conductivity by GO substrate.Furthermore,the f-CoNC/GO-assembled rechargeable Zn-air battery showed highly efficient and stable performance,demonstrating our pyrolysis-free method to be straightforward,cost-effective,and feasible for the scalable production of MNC electrocatalysts.展开更多
We present a qualitative and quantitative study of the magneto-thermoelectric effect of graphene. In the limit of impurity scattering length being much longer than the lattice constant, the intra-valley scattering dom...We present a qualitative and quantitative study of the magneto-thermoelectric effect of graphene. In the limit of impurity scattering length being much longer than the lattice constant, the intra-valley scattering dominates the charge and thermal transport. The self-energy and the Green's functions are calculated in the self-consistent Born approximation. It is found that the longitudinal thermal conductivity splits into double peaks at high Landau levels and exhibits oscillations which are out of phase with the electric conductivity. The chemical potential-dependent electrical resistivity, the thermal conductivities, the Seebeck coefficient, and the Nernst coefficient are obtained. The results are in good agreement with the experimental observations.展开更多
OBJECTIVE To retrospectively analyze clinical data of patientsfrom our hospital who underwent radical surgery for esophagealcarcinoma and for adenocarcinoma of the gastric cardia,as well asto investigate prognostic fa...OBJECTIVE To retrospectively analyze clinical data of patientsfrom our hospital who underwent radical surgery for esophagealcarcinoma and for adenocarcinoma of the gastric cardia,as well asto investigate prognostic factors affecting the long-term survival ofthe patients.METHODS Data from the patients eligible for our study,admitted to the 4th Hospital of Hebei Medical University fromJanuary 1996 to December 2004,were randomized,and 12distinctive clinicopathologic factors influencing the survival rateof those who underwent radical surgery for esophageal carcinomaor carcinoma of the gastric cardia were collected.Univariate andmultivariate analysis of these individual variables were performedusing the Cox proportional hazard model.RESULTS It was shown by univariate analysis that age,tumorsize,pathologic type,lymph node status,TNM staging,depthof infiltration and encroachment into local organs,etc.,were thefactors that markedly influenced the prognosis of patients(P<0.01).Multivariate analysis showed that pathologic type,numberof the lymph node metastases,involvement of local organs,andTNM staging were independent prognostic factors(P<0.05).CONCLUSION The independent factors influencing theprognosis of patients with esophageal cancer and carcinoma ofthe gastric cardia include pathologic type,number of lymph nodemetastases,involvement of local organs and TNM staging.Themain prognostic factors affecting the patient's survival are patientage,tumor size and depth of infiltration.In addition,patients withinvolvement of the local organs have a worse prognosis,and theyshould be closely followed up.展开更多
Background: China has one of the highest incidence rates of oesophageal cancer in the world. The role of human papillomavirus (HPV) has been extensively researched in oesophageal squamous cell carcinoma (OSCC) with in...Background: China has one of the highest incidence rates of oesophageal cancer in the world. The role of human papillomavirus (HPV) has been extensively researched in oesophageal squamous cell carcinoma (OSCC) with indeterminate results. The majority of these studies have been conducted in the Chinese population. Evidence for a definitive HPV-OSCC association could potentially support prophylactic vaccination in target populations, highlighting the need for ongoing investigation. The aim of this review is to summarise the findings of HPV DNA in OSCC tissue in Chinese subjects, with a view to informing further research in this area. Methods: A systematic literature search of the Chinese National Knowledge Infrastructure (CNKI) database, Medline, Embase and PubMed was conducted for all studies in English and Chinese language, examining OSCC tissue for HPV DNA in China. Reference lists of retrieved articles were reviewed and hand searches of relevant, key journals were conducted, to source articles which were not electronically indexed. Sixty-four studies met our selection criteria. Data from case-control and cross-sectional studies were analysed separately for any HPV-OSCC association, using the Epi InfoTM 3.5.3 software program. Results: From all studies conducted in the Chinese population, 2166/5953 (36%) of all OSCC tissue and 478/1684 (28%) of healthy control tissue, tested positive for HPV. We found that 11/16 case-control and cross-sectional studies had a statistically significant crude odds ratio, which supported a potential HPV-OSCC association. The largest study, carried out in the high incidence County of Anyang in Henan Province, reported 207/265 (78%) OSCC tissues testing positive for HPV DNA against 203/357 (57%) controls and had an unadjusted odds ratio of 2.71 (p-value Conclusion: A rigorous meta-analysis would improve interpretation of the data and a well-designed large-scale case-control study is warranted. If a link is found between HPV and OSCC, prophylactic HPV vaccines could be of significant benefit in China.展开更多
OBJECTIVE This research was to induce dendritic cells (DCs) from mice embryonic stem cells and bone marrow mononuclear cells in vitro, and then compare the biologic characteristics of them. METHODS Embryonic stem ce...OBJECTIVE This research was to induce dendritic cells (DCs) from mice embryonic stem cells and bone marrow mononuclear cells in vitro, and then compare the biologic characteristics of them. METHODS Embryonic stem cells (ESCs) suspending cultured in petri dishes were induced to generate embryonic bodies (EBs). Fourteen-day well-developed EBs were transferred to histological culture with the same medium and supplemented 25 ng/ml GM- CSF and 25 ng/ml IL-3. In the next 2 weeks, there were numerous immature DCs outgrown. Meantime, mononuclear cells isolated from mice bone marrow were induced to derive dendritic cells by supplementing 25 ng/ml GM-CSF and 25 ng/ml IL-4, and then the morphology, phenotype and function of both dendritic cells from different origins were examined. RESULTS Growing mature through exposure to lipopolysaccharide (LPS), both ESC-DCs and BM-DCs exhibited dramatic veils of cytoplasm and extensive dendrites on their surfaces, highly expressed CD11c, MHC-II and CD86 with strong capacity to stimulate primary T cell responses in mixed leukocyte reaction (MLR). CONCLUSION ESC-DC has the same biologic characteristics as BM-DC, and it provides a new, reliable source for the functional research of DC and next produce corresponding anti-tumor vaccine.展开更多
OBJECTIVE To investigate the clinicopathological features of esophageal carcinoma (EC) patients, and to analyze epidemiologic characteristics and the current situation of esophageal cancioma in the southern area of ...OBJECTIVE To investigate the clinicopathological features of esophageal carcinoma (EC) patients, and to analyze epidemiologic characteristics and the current situation of esophageal cancioma in the southern area of Hebei Province. METHODS A total of 4329 patients with esophageal cancinoma, undergoing surgery in the Fourth Hospital of Hebei Medical University during a period from January 1996 to December 2005, were selected. Collection and statistical analysis of the pathologic data were performed using a SAS 6.0 software package. RESULTS Over the past ten years, there has been a tendency for an increase in the mean age of EC onset (P 〈 0.05), a downtrend in the percentage of squamous cancer (SqCa) (P 〈 0.05) and an uptrend in the frequency of small cell carcinoma (P 〈 0.05). In clinical stages, there was a drop in the percentage of Stage-Ⅱ squamous EC patients (P 〈 0.05), and an increase in that of Stage-Ⅳ patients (P 〈 0.05). There were statistical differences in sex, age, pathologic types, depth of infiltration, ratio of stages and lymph node metastasis, etc. among the superior, middle and inferior segments of the EC diseased region (P 〈 0.05). CONCLUSION It was relatively late for the EC patients from this area to see a doctor, resulting in a drop in the ratio of SqCa and an ascensus in that of small cell cancer. However, due to a low incidence of adenocarcinoma, no obvious ascending tendency was found in the frequency of this carcinoma over the past ten years.展开更多
As a neurotransmitter and avascular active substance,the 5-hydroxytryptamine(5-HT,serotonin)is widely distributed in the central nervous system and surrounding tissues.The 5-HT can play its role by acting on its corre...As a neurotransmitter and avascular active substance,the 5-hydroxytryptamine(5-HT,serotonin)is widely distributed in the central nervous system and surrounding tissues.The 5-HT can play its role by acting on its corresponding 5-HT receptor.Nowadays,the 5-HT receptor can be classified into seven,according to different signal transduction method of receptors,the 5-HT3 receptor belongs to the ligandgated ion channels,while other six 5-HT receptors are involved into the G protein-coupled receptors and play the biological role by binding to specific G protein-coupled receptors(GPCRs)on the surface of the cell membrane.The 5-HT plays an important role in the brain-gut information transmission and studies showed that the physiological stimulations like having meals,and pathological stimulations like ischemia and stress could promote the release of the 5-HT.In the gastrointestinal tract,the 5-HT is closely related to gastrointestinal sensitivity,gastrointestinal movement and secretion regulation,as well as many gastrointestinal dysfunction disorders,such as gastrointestinal power and visceral sensitivity abnormality and abnormalities of brain-gut axis.展开更多
Peroxyacetyl nitrate(PAN)is an important photochemical pollutant in the troposphere,whereas long-term measurements are scarce in rural areas in North China Plain(NCP),resulting in unclear seasonal variations and sourc...Peroxyacetyl nitrate(PAN)is an important photochemical pollutant in the troposphere,whereas long-term measurements are scarce in rural areas in North China Plain(NCP),resulting in unclear seasonal variations and sources of PAN in rural NCP.In this study,we conducted a 1-year observation of PAN during 2021-2022 at the rural NCP site.The average concentrations of PAN were 1.10,0.75,0.65,and 0.88 ppbv in spring,summer,autumn,and winter,respectively,with a 1-year average of 0.81±0.60 ppbv.Calculations indicate that the loss of PAN through thermal decomposition in summer accounts for 43.2% of the total formed PAN,which is an important reason for the low concentration of PAN in summer.We speculate that since the correlation between PAN and O_(3) in winter is significantly lower than that in other seasons,the observed regional transport of PAN cannot be ignored in winter.Through budget analysis,regional transport accounted for 12.8% and 55.9% of the observed PAN on the spring and winter pollution days,respectively,which showed that regional transport played key roles during the photochemical pollution of the rural NCP in winter.The potential source contribution function revealed that the transported PAN mainly comes from southern Hebei in spring.In winter,the transported PAN was mainly from Langfang,Hengshui,and southern Beijing.Our findings may aid in understanding PAN variations in different seasons in rural areas and highlight the impact of regional transport on the PAN budget.展开更多
Iron-nitrogen-carbon single-atom catalysts(Fe-N-C SACs)are widely acknowledged for their effective oxygen reduction activity,however,their activity requires further enhancement.Meanwhile,additional structural optimiza...Iron-nitrogen-carbon single-atom catalysts(Fe-N-C SACs)are widely acknowledged for their effective oxygen reduction activity,however,their activity requires further enhancement.Meanwhile,additional structural optimization is necessary to enhance mass transport and achieve higher power density in practical applications.Herein,using ZIF-8 as a template,we synthesized yolk-shell catalysts featuring complex sites of Fe single atoms and Cu nanoclusters(y-FeCu/NC)via partial etching and liquid-phase loading.The synthesized y-FeCu/NC catalyst exhibits high specific surface area and mesoporous volume.Combined with the advantages of highly active sites and yolk-shell structure,the y-FeCu/NC catalyst demonstrated outstanding catalytic performance in the oxygen reduction reaction,achieving a half-wave potential(E_(1/2))of 0.97 V in 0.1 M KOH.As a practical energy device,Zn-air battery(ZAB)assembled with y-FeCu/NC catalyst achieved a remarkable power density of 356.3 mW·cm^(-2),representing an improvement of approximately 28.5%compared to its solid FeCu/NC counterpart.Furthermore,it showcased impressive stability,surpassing all control samples.展开更多
The conventional multilevel inverters(MLIs)have the disadvantages of numerous devices,incapacity of boost,unbalance for capacitor’s voltage,high complexity for control,and etc.Motivated by this issue,a seven-level bo...The conventional multilevel inverters(MLIs)have the disadvantages of numerous devices,incapacity of boost,unbalance for capacitor’s voltage,high complexity for control,and etc.Motivated by this issue,a seven-level boost inverter(7LBI)based on a switched capacitor is presented for singlephase applications in this paper.The proposed 7LBI using only seven transistors can achieve seven output levels,1.5 voltage gain,and natural balance of capacitors’voltages without sensors or other auxiliary methods,which illustrates its suitability for the applications of renewable energy generation.The configuration of topology and operating principles are illustrated in detail.The natural balance of capacitors and capacitance calculations are deduced as well.Moreover,the comparative study is conducted for different types of MLIs.The results illustrate the merits of the proposed 7LBI with respect to reduced devices,lower voltage stress,and less power loss.Finally,a simulation for the proposed 7LBI with PWM modulation is realized based on the theoretical analysis;an experimental prototype is also implemented,verifying multilevel output,boost ability,natural balance for switched capacitors,and performance of transient response.展开更多
基金financially supported by the Jiangsu Distinguished Professors Project(No.1711510024)the funding for Scientific Research Startup of Jiangsu University(Nos.4111510015,19JDG044)+3 种基金the Jiangsu Provincial Program for High-Level Innovative and Entrepreneurial Talents Introductionthe National Natural Science Foundation of China(No.22008091)Natural Science Foundation of Guangdong Province(2023A1515010894)the Open Project of Luzhou Key Laboratory of Fine Chemical Application Technology(HYJH-2302-A).
文摘Silicon(Si)has emerged as a potent anode material for lithium-ion batteries(LIBs),but faces challenges like low electrical conductivity and significant volume changes during lithiation/delithiation,leading to material pulverization and capacity degradation.Recent research on nanostructured Si aims to mitigate volume expansion and enhance electrochemical performance,yet still grapples with issues like pulverization,unstable solid electrolyte interface(SEI)growth,and interparticle resistance.This review delves into innovative strategies for optimizing Si anodes’electrochemical performance via structural engineering,focusing on the synthesis of Si/C composites,engineering multidimensional nanostructures,and applying non-carbonaceous coatings.Forming a stable SEI is vital to prevent electrolyte decomposition and enhance Li^(+)transport,thereby stabilizing the Si anode interface and boosting cycling Coulombic efficiency.We also examine groundbreaking advancements such as self-healing polymers and advanced prelithiation methods to improve initial Coulombic efficiency and combat capacity loss.Our review uniquely provides a detailed examination of these strategies in real-world applications,moving beyond theoretical discussions.It offers a critical analysis of these approaches in terms of performance enhancement,scalability,and commercial feasibility.In conclusion,this review presents a comprehensive view and a forward-looking perspective on designing robust,high-performance Si-based anodes the next generation of LIBs.
基金financially supported by the Jiangsu Distinguished Professors Project (No.1711510024)the Funding for Scientific Research Startup of Jiangsu University (No.4111510015,19JDG044)+5 种基金the Jiangsu Provincial Program for High-Level Innovative and Entrepreneurial Talents Introductionthe National Natural Science Foundation of China (No.22008091)the Jiangsu Agriculture Science and Technology Innovation Fund (No.CX (21)1007)the Natural Science Foundation of Guangdong Province (2023A1515010894)the Open Project of Luzhou Key Laboratory of Fine Chemical Application Technology (HYJH-2302-A)the National Institute of Education,Singapore,under its Academic Research Fund (RI 1/21 EAH)。
文摘Aqueous zinc-ion batteries possess substantial potential for energy storage applications;however,they are hampered by challenges such as dendrite formation and uncontrolled side reactions occurring at the zinc anode.In our investigation,we sought to mitigate these issues through the utilization of in situ zinc complex formation reactions to engineer hydrophobic protective layers on the zinc anode surface.These robust interfacial layers serve as effective barriers,isolating the zinc anode from the electrolyte and active water molecules and thereby preventing hydrogen evolution and the generation of undesirable byproducts.Additionally,the presence of numerous zincophilic sites within these protective layers facilitates uniform zinc deposition while concurrently inhibiting dendrite growth.Through comprehensive evaluation of functional anodes featuring diverse functional groups and alkyl chain lengths,we meticulously scrutinized the underlying mechanisms influencing performance variations.This analysis involved precise modulation of interfacial hydrophobicity,rapid Zn^(2+)ion transport,and ordered deposition of Zn^(2+)ions.Notably,the optimized anode,fabricated with octadecylphosphate(OPA),demonstrated exceptional performance characteristics.The Zn//Zn symmetric cell exhibited remarkable longevity,exceeding 4000 h under a current density of 2 mA cm^(-2)and a capacity density of 2 mA h cm^(-2),Furthermore,when integrated with a VOH cathode,the complete cell exhibited superior capacity retention compared to anodes modified with alternative organic molecules.
基金the National Natural Sci-ence Foundation of China(Grant No.61988102)the Key Research and Development Program of Guangdong Province(Grant No.2019B090917007)+5 种基金the Science and Technology Planning Project of Guangdong Province(Grant No.2019B090909011)Q.L.acknowledges Guangzhou Basic and Applied Basic Research Project(Grant No.2023A04J0018)Z.L.acknowledges the support of fund-ing from Chinese Academy of Sciences E1Z1D10200 and E2Z2D10200from ZJ project 2021QN02X159 and from JSPS(Grant Nos.PE14052 and P16027)We gratefully ac-knowledge HZWTECH for providing computation facilities.Z.-X.H.was supported by the National Natural Science Foun-dation of China(Grant Nos.11974064 and 12147102)the Fundamental Research Funds for the Central Universities(Grant No.2020CDJQY-Z003).
文摘We develop a numerical method for the time evolution of Gaussian wave packets on flat-band lattices in the presence of correlated disorder.To achieve this,we introduce a method to generate random on-site energies with prescribed correlations.We verify this method with a one-dimensional(1D)cross-stitch model,and find good agreement with analytical results obtained from the disorder-dressed evolution equations.This allows us to reproduce previous findings,that disorder can mobilize 1D flat-band states which would otherwise remain localized.As explained by the corresponding disorder-dressed evolution equations,such mobilization requires an asymmetric disorder-induced coupling to dispersive bands,a condition that is generically not fulfilled when the flat-band is resonant with the dispersive bands at a Dirac point-like crossing.We exemplify this with the 1D Lieb lattice.While analytical expressions are not available for the two-dimensional(2D)system due to its complexity,we extend the numerical method to the 2D a–T3 model,and find that the initial flat-band wave packet preserves its localization when a=0,regardless of disorder and intersections.However,when a̸=0,the wave packet shifts in real space.We interpret this as a Berry phase controlled,disorder-induced wave-packet mobilization.In addition,we present density functional theory calculations of candidate materials,specifically Hg1−xCdxTe.The flat-band emerges near the G point(α=0)in the Brillouin zone.
基金supported by the Open Project Program of Irradiation Preservation Technology Key Laboratory of Sichuan Province,Sichuan Institute of Atomic Energy(FZBC2020009)the Open Research Fund Program of Departmental and Municipal Co-construction of Crops Genetic Improvement of Hill Land Key Laboratory of Sichuan Province(2021CGIHL02)+2 种基金Science and Technology Support Project of Nanchong Science and Technology Bureau of Sichuan Province(20YFZJ0053 and 20YFZJ0054)the Sericulture Innovation Team of Sichuan Province(SCCXTD-2021-17)Laboratory of Sichuan Province(2021CGIHL02)。
文摘A new water-soluble heteropolysaccharide with a molecular weight of 15 k Da was isolated from the fruiting bodies of Boletus reticulatus Schaeff.Structural characterization results revealed that B.reticulatus Schaeff polysaccharide(BRS-X)had a backbone of 1,6-linkedα-D-galactose and 1,2,6-linkedα-D-galactose which branches were mainly composed of a terminal 4-linkedβ-D-glucose and the ratio of D-galactose and D-glucose was 5:1.Bioactivity assays indicated that BRS-X displayed a strong proliferative activity in T cells and B cells and promoted the secretion of immunoglobulin G(Ig G),Ig E,Ig D and Ig M.In addition,BRS-X could facilitate the proliferation and phagocytosis of RAW264.7 cells and could significantly inhibit the growth of tumors in S180-bearing mice.The results of transcriptome sequencing analysis illustrated that total 46 genes enriched in MAPK and total 34 genes enriched in PI3 K/Akt signaling pathways in BRS-X group.The protein VEGF and VEGFR expression were significantly reduced under the treatment with BRS-X.These findings provide a scientific basis for the edible and medicinal value of BRS-X.
基金financially supported by the National Natural Science Foundation of China(U1707603,21521005,21975013,21901017)the National Key Research and Development Program of China(2017YFA0206500,2018YFA0702000)+2 种基金Beijing Natural Science Foundation(2172042)PetroChina Innovation Foundationthe Fundamental Research Funds for the Central Universities。
文摘With exhaustion of fossil fuels and the deterioration of global environment,widespread and intensive researches have been concentrated on clean and sustainable alternative energy sources,such as metal-air batteries[1],fuel cells[2]and water splitting devices[3].Electrocatalytic oxidation of water to O2(oxygen evolution reaction,OER)is a vital chemical process involved in energy storage and conversion from renewable sources in form of molecular fuels such as H2 via water electrolysis,which has attracted a great amount of research efforts in the past few years[4,5].Nowadays,RuO2 and IrO2 are widely used as typical excellent OER electrocatalysts.However,their high-cost and scarce nature restricts the broadly commercial application of those materials[6,7].Hence,there is an urgent demand to develop low cost,highly efficient,and superb stable OER catalysts.
基金National Natural Science Foundation of China(61331019,61490691)。
文摘The problem addressed in this paper concerns the extension of widely linear beamforming to the wideband case,developing a wide-focused linear beamformer for the extraction of a wideband second-order(SO)noncircular signal-of-interest(SOI)contaminated by uncorrelated interferences and noise.In the proposed beamformer,the beamforming array observation is first focused to adopt a standard linear minimum variance distortionless response(MVDR)framework.The augmented SOI steering vector then is obtained by estimating the SOI noncircularity parameter with the newly proposed oblique projection with an augmented sparse representation scheme.The covariance matrix of the virtual interference,true interference and noise is further reconstructed using the newly presented complementary spatial spectrum technique.The wideband widely linear spatial filtering is finally realized via MVDR like beamforming.The performance of the proposed beamformer is verified by simulation.
基金financial support from the National Natural Sciences Foundation of China(41401041)and the National Basic Research Program of China(2013CBA01806)
文摘Many rivers originate in high mountainous regions. However, the effects of climate warming on the runoff and water balance in these regions remain unclear due to the lack of observational data from harsh environments, and the variable influences of climate change on alpine land-cover types with different water balances. Using observations and simulations from Coup Model, water-balance values collected at five alpine land-cover types(steppe, shrub meadow, moist meadow, swamp meadow, and moraine) in a small alpine watershed, the Qilian Mountains in Northwest China, from October 2008 to September 2014, were compared. Measured evapotranspiration, multilayer soil temperatures and water contents, and frozen-depth data were used to validate Coup Model outputs. The results show that elevation is the primary influence on precipitation, evapotranspiration, and runoff coefficients in alpine regions. Land-cover types at higher elevations receive more precipitation and have a larger runoff coefficient. Notably, climate warming not only increases evapotranspiration but also particularly increases the evapotranspiration/precipitation ratio due to an upward shift in the optimum elevation of plant species. These factors lead to decrease runoff coefficients in alpine basins.
基金This work was supported by a grant from the Hebei Provincial Program for Subjects with High Scholarship and Creative Research Potential
文摘OBJECTIVE To summarize the regular pattern and state oflymph node metastasis of patients with esophageal and cardiaccarcinomas,so as to analyze factors influencing lymph nodemetastasis.METHODS Clinical data collected from 1,526 thoracicesophageal and cardiac carcinoma patients who were admitted inthe Fourth Hospital of Hebei Medical University during a periodfrom January 1996 to December 2004,were randomly selectedand an Access Database of the patient's information was set up.Eight clinico-pathologic factors,including the patient's age,tumorlocation and size,pathological classification,the depth of tumorinvasion,vascular tumor embolus (VTE),the state of surroundingorgan encroachment and the status of tumor residues,wereidentified.A correlation between these factors and metastases wasstatistically analyzed using SPSS13.0 software.RESULTS Lymph node metastatic sites from esophagealcarcinomas included the thoracic and abdominal cavity.Lymphnode metastasis from the superior esophageal carcinomasmainly occurred in the neck and thoracic cavity.There was atwo-way lymph node metastasis in the patients with the middleesophageal carcinoma.The inferior esophageal carcinomas mainlymetastasized to the paraesophageal,paragastric cardia,and leftgastric artery lymph nodes.The rate and degree of the metastasisfrom the inferior esophageal carcinomas were significantly highercompared to those of the superior and the middle esophagealcarcinomas (P<0.0125).The degree of abdominal lymph node metastasis fromcarcinomas of the gastric cardia was significantly higher comparedwith that of esophageal carcinomas.In the group with carcinomaof the gastric cardia,the rate and degree of the lymph nodemetastases in the paragastric cardia and left gastric artery weresignificantly higher compared to the group with esophagealcarcinoma (P<0.05).Paraesophageal lymph node metastasis fromcarcinomas of the gastric cardia in the thoracic cavity frequentlyoccurred,too,and the degree of the metastasis was similar to thatof esophageal carcinoma.There was no significant difference inthe rate and degree of the paraesophageal lymph-node metastasisbetween the group with carcinoma of the gastric cardia comparedto those with esophageal carcinoma (P>0.05).Multifactoriallogistic regression analysis showed that the tumor size,depth oftumor encroachment,VTE,and tumor residues could all bringabout obvious impact on lymph-node metastases (P<0.05).CONCLUSION Lymph node metastasis from superioresophageal carcinomas mainly occurs in the neck and thoraciccavity.The middle esophageal carcinomas presented a two-waylymph-node metastasis (both the upwards and the downwards),and the lymph node metastasis from inferior esophagealcarcinomas mainly occurred in the thoracic and abdominal cavities.The metastases of carcinoma of the gastriccardia were most commonly found in the abdominalcavity,with frequent paraesophageal lymph-nodemetastasis.The sufficient attention should be paidto neck lymph node clearance in cases of esophagealcarcinoma.What is of the greatest concern is theclearance of the left gastric artery lymph nodes,andalso in cases of gastric cardia carcinoma,clearance,the paraesophageal lymph nodes.With an increasein the tumor size and depth of tumor encroachment,and occurrence of VTE and tumor residual cells,therisk of lymph node metastasis is significantly raised (P<0.05).
文摘With the continuous advancement of China’s infrastructure construction to the west,according to the geographic situation in the southwest region,such as mountainous areas and complex terrain,the road construction process is inevitably accompanied by earth and rock blasting.To improve the quality and safety of the project,this paper addresses the problems of land and rock blasting faced in the construction of mountain road projects,taking the research of rock dynamic mechanics test as the starting point,and using a combination of theoretical analysis and experimental research methods.The specific research content includes the following parts:dynamic impact compression test(SHPB),dynamic splitting tensile test,and stress-strain curve analysis of the test results,which provides the theoretical basis and numerical parameters for the numerical simulation of future engineering blasting.
基金financially supported by the National Natural Science Foundation of China(NSFC,21520102002,91622116,and 21701101)the National Key Research and Development Project(2016YFF0204402)+2 种基金the Fundamental Research Funds for the Central Universitiesthe Long-Term Subsidy Mechanism from the Ministry of Finance and the Ministry of Education of Chinathe Shandong Scientific Research Awards Foundation for Outstanding Young Scientists(ZR2018JL010)。
文摘Non-precious metal-nitrogen-carbon(MNC)electrocatalysts have gained tremendous attention as promising electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).However,the most applicable strategies for the synthesis of MNC materials heavily rely on pyrolysis treatment,which may easily lead to metal aggregation and subsequent degradation of catalytic performance.Herein,we developed a pyrolysis-free strategy for preparing MNC materials,which was demonstrated by achieving ultrathin cobalt-nitrogen-carbon(Co NC)layer with dense atomically dispersed cobalt sites depositing on graphene oxide(GO)via simple treatment of Co salt and GO in formamide.The formamide-derived Co NC layer deposited on GO(termed as f-Co NC/GO)could be controlled in 1-2 nm thick.Remarkably,the f-CoNC/GO composite without pyrolysis exhibited excellent bifunctional performance toward ORR and OER,which was attributed to the dense atomically dispersed Co-Nxsites and improved conductivity by GO substrate.Furthermore,the f-CoNC/GO-assembled rechargeable Zn-air battery showed highly efficient and stable performance,demonstrating our pyrolysis-free method to be straightforward,cost-effective,and feasible for the scalable production of MNC electrocatalysts.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11274013 and 11774006)the National Basic Research Program of China(2012CB921300)the Australian Research Council Grant(Grant No.DP160101474)
文摘We present a qualitative and quantitative study of the magneto-thermoelectric effect of graphene. In the limit of impurity scattering length being much longer than the lattice constant, the intra-valley scattering dominates the charge and thermal transport. The self-energy and the Green's functions are calculated in the self-consistent Born approximation. It is found that the longitudinal thermal conductivity splits into double peaks at high Landau levels and exhibits oscillations which are out of phase with the electric conductivity. The chemical potential-dependent electrical resistivity, the thermal conductivities, the Seebeck coefficient, and the Nernst coefficient are obtained. The results are in good agreement with the experimental observations.
基金supported by the Hebei Provincial Program for the Subjects with High Scholarship and Creative Research Potential,China.
文摘OBJECTIVE To retrospectively analyze clinical data of patientsfrom our hospital who underwent radical surgery for esophagealcarcinoma and for adenocarcinoma of the gastric cardia,as well asto investigate prognostic factors affecting the long-term survival ofthe patients.METHODS Data from the patients eligible for our study,admitted to the 4th Hospital of Hebei Medical University fromJanuary 1996 to December 2004,were randomized,and 12distinctive clinicopathologic factors influencing the survival rateof those who underwent radical surgery for esophageal carcinomaor carcinoma of the gastric cardia were collected.Univariate andmultivariate analysis of these individual variables were performedusing the Cox proportional hazard model.RESULTS It was shown by univariate analysis that age,tumorsize,pathologic type,lymph node status,TNM staging,depthof infiltration and encroachment into local organs,etc.,were thefactors that markedly influenced the prognosis of patients(P<0.01).Multivariate analysis showed that pathologic type,numberof the lymph node metastases,involvement of local organs,andTNM staging were independent prognostic factors(P<0.05).CONCLUSION The independent factors influencing theprognosis of patients with esophageal cancer and carcinoma ofthe gastric cardia include pathologic type,number of lymph nodemetastases,involvement of local organs and TNM staging.Themain prognostic factors affecting the patient's survival are patientage,tumor size and depth of infiltration.In addition,patients withinvolvement of the local organs have a worse prognosis,and theyshould be closely followed up.
文摘Background: China has one of the highest incidence rates of oesophageal cancer in the world. The role of human papillomavirus (HPV) has been extensively researched in oesophageal squamous cell carcinoma (OSCC) with indeterminate results. The majority of these studies have been conducted in the Chinese population. Evidence for a definitive HPV-OSCC association could potentially support prophylactic vaccination in target populations, highlighting the need for ongoing investigation. The aim of this review is to summarise the findings of HPV DNA in OSCC tissue in Chinese subjects, with a view to informing further research in this area. Methods: A systematic literature search of the Chinese National Knowledge Infrastructure (CNKI) database, Medline, Embase and PubMed was conducted for all studies in English and Chinese language, examining OSCC tissue for HPV DNA in China. Reference lists of retrieved articles were reviewed and hand searches of relevant, key journals were conducted, to source articles which were not electronically indexed. Sixty-four studies met our selection criteria. Data from case-control and cross-sectional studies were analysed separately for any HPV-OSCC association, using the Epi InfoTM 3.5.3 software program. Results: From all studies conducted in the Chinese population, 2166/5953 (36%) of all OSCC tissue and 478/1684 (28%) of healthy control tissue, tested positive for HPV. We found that 11/16 case-control and cross-sectional studies had a statistically significant crude odds ratio, which supported a potential HPV-OSCC association. The largest study, carried out in the high incidence County of Anyang in Henan Province, reported 207/265 (78%) OSCC tissues testing positive for HPV DNA against 203/357 (57%) controls and had an unadjusted odds ratio of 2.71 (p-value Conclusion: A rigorous meta-analysis would improve interpretation of the data and a well-designed large-scale case-control study is warranted. If a link is found between HPV and OSCC, prophylactic HPV vaccines could be of significant benefit in China.
基金supported by a grant from Program for New Century Excellent Talents in University,China(No.NECT-05-0820).
文摘OBJECTIVE This research was to induce dendritic cells (DCs) from mice embryonic stem cells and bone marrow mononuclear cells in vitro, and then compare the biologic characteristics of them. METHODS Embryonic stem cells (ESCs) suspending cultured in petri dishes were induced to generate embryonic bodies (EBs). Fourteen-day well-developed EBs were transferred to histological culture with the same medium and supplemented 25 ng/ml GM- CSF and 25 ng/ml IL-3. In the next 2 weeks, there were numerous immature DCs outgrown. Meantime, mononuclear cells isolated from mice bone marrow were induced to derive dendritic cells by supplementing 25 ng/ml GM-CSF and 25 ng/ml IL-4, and then the morphology, phenotype and function of both dendritic cells from different origins were examined. RESULTS Growing mature through exposure to lipopolysaccharide (LPS), both ESC-DCs and BM-DCs exhibited dramatic veils of cytoplasm and extensive dendrites on their surfaces, highly expressed CD11c, MHC-II and CD86 with strong capacity to stimulate primary T cell responses in mixed leukocyte reaction (MLR). CONCLUSION ESC-DC has the same biologic characteristics as BM-DC, and it provides a new, reliable source for the functional research of DC and next produce corresponding anti-tumor vaccine.
文摘OBJECTIVE To investigate the clinicopathological features of esophageal carcinoma (EC) patients, and to analyze epidemiologic characteristics and the current situation of esophageal cancioma in the southern area of Hebei Province. METHODS A total of 4329 patients with esophageal cancinoma, undergoing surgery in the Fourth Hospital of Hebei Medical University during a period from January 1996 to December 2005, were selected. Collection and statistical analysis of the pathologic data were performed using a SAS 6.0 software package. RESULTS Over the past ten years, there has been a tendency for an increase in the mean age of EC onset (P 〈 0.05), a downtrend in the percentage of squamous cancer (SqCa) (P 〈 0.05) and an uptrend in the frequency of small cell carcinoma (P 〈 0.05). In clinical stages, there was a drop in the percentage of Stage-Ⅱ squamous EC patients (P 〈 0.05), and an increase in that of Stage-Ⅳ patients (P 〈 0.05). There were statistical differences in sex, age, pathologic types, depth of infiltration, ratio of stages and lymph node metastasis, etc. among the superior, middle and inferior segments of the EC diseased region (P 〈 0.05). CONCLUSION It was relatively late for the EC patients from this area to see a doctor, resulting in a drop in the ratio of SqCa and an ascensus in that of small cell cancer. However, due to a low incidence of adenocarcinoma, no obvious ascending tendency was found in the frequency of this carcinoma over the past ten years.
基金Effect of 5-hydroxytryptamine Receptor in the Lower Esophageal Sphincter Regulation Mechanism(NO.18ZF23)。
文摘As a neurotransmitter and avascular active substance,the 5-hydroxytryptamine(5-HT,serotonin)is widely distributed in the central nervous system and surrounding tissues.The 5-HT can play its role by acting on its corresponding 5-HT receptor.Nowadays,the 5-HT receptor can be classified into seven,according to different signal transduction method of receptors,the 5-HT3 receptor belongs to the ligandgated ion channels,while other six 5-HT receptors are involved into the G protein-coupled receptors and play the biological role by binding to specific G protein-coupled receptors(GPCRs)on the surface of the cell membrane.The 5-HT plays an important role in the brain-gut information transmission and studies showed that the physiological stimulations like having meals,and pathological stimulations like ischemia and stress could promote the release of the 5-HT.In the gastrointestinal tract,the 5-HT is closely related to gastrointestinal sensitivity,gastrointestinal movement and secretion regulation,as well as many gastrointestinal dysfunction disorders,such as gastrointestinal power and visceral sensitivity abnormality and abnormalities of brain-gut axis.
基金supported by the National Natural Science Foundation of China(Nos.21976190,41727805,41975164,22076202,42275111,41931287,and 42130714)。
文摘Peroxyacetyl nitrate(PAN)is an important photochemical pollutant in the troposphere,whereas long-term measurements are scarce in rural areas in North China Plain(NCP),resulting in unclear seasonal variations and sources of PAN in rural NCP.In this study,we conducted a 1-year observation of PAN during 2021-2022 at the rural NCP site.The average concentrations of PAN were 1.10,0.75,0.65,and 0.88 ppbv in spring,summer,autumn,and winter,respectively,with a 1-year average of 0.81±0.60 ppbv.Calculations indicate that the loss of PAN through thermal decomposition in summer accounts for 43.2% of the total formed PAN,which is an important reason for the low concentration of PAN in summer.We speculate that since the correlation between PAN and O_(3) in winter is significantly lower than that in other seasons,the observed regional transport of PAN cannot be ignored in winter.Through budget analysis,regional transport accounted for 12.8% and 55.9% of the observed PAN on the spring and winter pollution days,respectively,which showed that regional transport played key roles during the photochemical pollution of the rural NCP in winter.The potential source contribution function revealed that the transported PAN mainly comes from southern Hebei in spring.In winter,the transported PAN was mainly from Langfang,Hengshui,and southern Beijing.Our findings may aid in understanding PAN variations in different seasons in rural areas and highlight the impact of regional transport on the PAN budget.
基金supported by the National Key Research and Development Program of China(No.2022YFC2105900).
文摘Iron-nitrogen-carbon single-atom catalysts(Fe-N-C SACs)are widely acknowledged for their effective oxygen reduction activity,however,their activity requires further enhancement.Meanwhile,additional structural optimization is necessary to enhance mass transport and achieve higher power density in practical applications.Herein,using ZIF-8 as a template,we synthesized yolk-shell catalysts featuring complex sites of Fe single atoms and Cu nanoclusters(y-FeCu/NC)via partial etching and liquid-phase loading.The synthesized y-FeCu/NC catalyst exhibits high specific surface area and mesoporous volume.Combined with the advantages of highly active sites and yolk-shell structure,the y-FeCu/NC catalyst demonstrated outstanding catalytic performance in the oxygen reduction reaction,achieving a half-wave potential(E_(1/2))of 0.97 V in 0.1 M KOH.As a practical energy device,Zn-air battery(ZAB)assembled with y-FeCu/NC catalyst achieved a remarkable power density of 356.3 mW·cm^(-2),representing an improvement of approximately 28.5%compared to its solid FeCu/NC counterpart.Furthermore,it showcased impressive stability,surpassing all control samples.
基金supported by the National Natural Science Foundation of China under Grants 62173148 and 52377186,and Joint Laboratory of Energy Saving and Intelligent Maintenance for Modern Transportations。
文摘The conventional multilevel inverters(MLIs)have the disadvantages of numerous devices,incapacity of boost,unbalance for capacitor’s voltage,high complexity for control,and etc.Motivated by this issue,a seven-level boost inverter(7LBI)based on a switched capacitor is presented for singlephase applications in this paper.The proposed 7LBI using only seven transistors can achieve seven output levels,1.5 voltage gain,and natural balance of capacitors’voltages without sensors or other auxiliary methods,which illustrates its suitability for the applications of renewable energy generation.The configuration of topology and operating principles are illustrated in detail.The natural balance of capacitors and capacitance calculations are deduced as well.Moreover,the comparative study is conducted for different types of MLIs.The results illustrate the merits of the proposed 7LBI with respect to reduced devices,lower voltage stress,and less power loss.Finally,a simulation for the proposed 7LBI with PWM modulation is realized based on the theoretical analysis;an experimental prototype is also implemented,verifying multilevel output,boost ability,natural balance for switched capacitors,and performance of transient response.