The catalyst layers(CLs) electrode is the key component of the membrane electrode assembly(MEA) in proton exchange membrane fuel cells(PEMFCs). Conventional electrodes for PEMFCs are composed of carbon-supported, iono...The catalyst layers(CLs) electrode is the key component of the membrane electrode assembly(MEA) in proton exchange membrane fuel cells(PEMFCs). Conventional electrodes for PEMFCs are composed of carbon-supported, ionomer, and Pt nanoparticles, all immersed together and sprayed with a micron-level thickness of CLs. They have a performance trade-off where increasing the Pt loading leads to higher performance of abundant triple-phase boundary areas but increases the electrode cost. Major challenges must be overcome before realizing its wide commercialization. Literature research revealed that it is impossible to achieve performance and durability targets with only high-performance catalysts, so the controllable design of CLs architecture in MEAs for PEMFCs must now be the top priority to meet industry goals. From this perspective, a 3D ordered electrode circumvents this issue with a support-free architecture and ultrathin thickness while reducing noble metal Pt loadings. Herein, we discuss the motivation in-depth and summarize the necessary CLs structural features for designing ultralow Pt loading electrodes. Critical issues that remain in progress for 3D ordered CLs must be studied and characterized. Furthermore, approaches for 3D ordered CLs architecture electrode development, involving material design, structure optimization, preparation technology, and characterization techniques, are summarized and are expected to be next-generation CLs for PEMFCs. Finally, the review concludes with perspectives on possible research directions of CL architecture to address the significant challenges in the future.展开更多
The Kyushu–Palau Ridge(KPR),an anti-S-shaped submarine highland at the center of the Philippine Sea Plate(PSP),is considered the residual arc of the Izu–Bonin–Mariana Island Arc,which retains key information about ...The Kyushu–Palau Ridge(KPR),an anti-S-shaped submarine highland at the center of the Philippine Sea Plate(PSP),is considered the residual arc of the Izu–Bonin–Mariana Island Arc,which retains key information about the cessation of the Western Philippine Basin(WPB)expansion and the Parece Vela Basin(PVB)breakup.Herein,using the new generation of satellite altimetry gravity data,high-precision seafloor topography data,and newly acquired ship-borne gravity data,the topographic and gravity characteristics of the KPR mid-southern section and adjacent region are depicted.The distribution characteristics of the faults were delineated using the normalized vertical derivative–total horizontal derivative method(NVDR-THDR)and the minimum curvature potential field separation method.The Moho depth and crustal thickness were inverted using the rapid inversion method for a double-interface model with depth constraints.Based on these results,the crust structure features in the KPR mid-southern section,and the“triangular”structure geological significance where the KPR and Central Basin Rift(CBR)of the WPB intersect are interpreted.The KPR crustal thickness is approximately 6–16 km,with a distinct discontinuity that is slightly thicker than the normal oceanic crust.The KPR mid-southern section crust structure was divided into four segments(S1–S4)from north to south,formed by the CBR eastward extension joint action and clockwise rotation of the PVB expansion axis and the Mindanao fault zone blocking effect.展开更多
Fushun oil shale(FOS) was subjected to thermal dissolution(TD) under different conditions. The results show that the optimal solvent, temperature, time, and ratio of solvent to FOS are ethanol, 300 °C, 2 h, and 5...Fushun oil shale(FOS) was subjected to thermal dissolution(TD) under different conditions. The results show that the optimal solvent, temperature, time, and ratio of solvent to FOS are ethanol, 300 °C, 2 h, and 5 ml·g^(-1),respectively and the corresponding yield of the soluble portion(SP) is 32.2%(daf), which is much higher than the oil content of FOS(ca. 6%), suggesting that TD in ethanol is an excellent way to extract organics from FOS.According to 3 direct analyses, aliphatic moieties in FOS are the most abundant followed by C\\O-containing moieties and each cluster in FOS has 3 conjugated aromatic rings on average with fewer substituents. According to the analysis with a gas chromatograph/mass spectrometer, alkanes are predominant in all the SPs. A number of alkenes were identified in the SPs from the TD, while none of the alkenes were detected in acetone-SP obtained at room temperature, implying that the TD can destroy the π-π and intertwining interactions between alkenes and macromolecular structures in FOS. Moreover, a small amount of alkyl-substituted phenols and alkoxysubstituted phenols were detected in ethanol-SP from the TD, which could be the products from ethanolyzing the macromolecular moiety of FOS.展开更多
Fortunella margarita（Lour.） Swingle, commonly known as kumquat, is the smallest citrus fruit. It thrives in southeastern China and is widely cultivated and consumed in the world due to its multiple health benefits. ...Fortunella margarita（Lour.） Swingle, commonly known as kumquat, is the smallest citrus fruit. It thrives in southeastern China and is widely cultivated and consumed in the world due to its multiple health benefits. It has been used as an important herbal medicine in traditional Chinese medicine and also as one of the most popular fruits. There are various kinds of bioactive compounds in F. margarita, such as polysaccharides, limonoids, essential oils, flavonoids, phenolic acids, vitamins, dietary fiber, etc. In addition, many studies have reported that these bioactive compounds can be used as antioxidant, antimicrobial, hypolipidemic, drosophila lure components in functional foods, pharmaceuticals and daily chemical products due to their biological activities. This review focuses on the structural features and biological activities of polysaccharides, limonoids, essential oils and flavonoids and other bioactive substances from F. margarita and their potential applications in food, daily chemical and pharmaceutical industries.展开更多
Handwriting recognition is one of the most significant problems in pattern recognition,many studies have been proposed to improve this recognition of handwritten text for different languages.Yet,Fewer studies have bee...Handwriting recognition is one of the most significant problems in pattern recognition,many studies have been proposed to improve this recognition of handwritten text for different languages.Yet,Fewer studies have been done for the Arabic language and the processing of its texts remains a particularly distinctive problem due to the variability of writing styles and the nature of Arabic scripts compared to other scripts.The present paper suggests a feature extraction technique for offlineArabic handwriting recognition.A handwriting recognition system for Arabic words using a few important structural features and based on a Radial Basis Function(RBF)neural networks is proposed.The methods of feature extraction are central to achieve high recognition performance.The proposed methodology relies on a feature extraction technique based on many structural characteristics extracted from the word skeleton(subwords,diacritics,loops,ascenders,and descenders).In order to reach our purpose,we built our own word database and the proposed system has been successfully tested on a handwriting database of Algerian city names(wilayas).Finally,a simple classifier based on the radial basis function neural network is presented to recognize certain words to verify the reliability of the proposed feature extraction.The experiments on some images of the benchmark IFN/ENIT database show that the proposed system improves recognition and the results obtained are indicative of the efficiency of our technique.展开更多
Tropoje-Has ophiolitic massif of eastern Mirdita(Albania)ophiolitic belt,is a major source for metallurgical chromite ore in Albania.Massif consists of a thick mantle section of SSZ type,8-10 km thick and
A new subtropical front near the periphery of the West Pacific subtropical anticyclone is found,which is never revealed in previous studies.The coupling of the subtropical front and Meiyu front forms a Meiyu front sys...A new subtropical front near the periphery of the West Pacific subtropical anticyclone is found,which is never revealed in previous studies.The coupling of the subtropical front and Meiyu front forms a Meiyu front system (MFS) and is the most direct synoptic system for the Meiyu precipitation along the Mid-lower Reaches of Yangtze River (MRYR) in China.In this paper.The detailed structural features and cloud features of the MFS in 1998 and 1999 are analyzed,which manifests that the MFS is an objective phenomenon over the period of Meiyu along MRYR and the Southwest Japan.Generally.the subtropical front is mainly located between 850 hPa and 500 hPa.The moist southwest monsoon is transported in the passageway between the Meiyu front and the subtropical front.The vertical motion ascends in the passageway and descends on both sides of the MFS.forming the MFS's secondary circulation.A lower TBB band indicated that obvious convective activities are also located in the passageway of MFS.The horizontal wind of MFS is vertically asymmetric.展开更多
The Acoustic nonlinearity parameter is an important parameter in nonlinear acoustics. In this article, the nonlinearity parameter B / A of normal and eight kinds of pathological porcine liver tissues were measured by ...The Acoustic nonlinearity parameter is an important parameter in nonlinear acoustics. In this article, the nonlinearity parameter B / A of normal and eight kinds of pathological porcine liver tissues were measured by finite amplitude insert-substitution method. The mixture law for nonlinearity parameter is used to analyze and predict the volume fractions of the components in a given tissue. It was found that the nonlinearity parameter is sensitive to the pathological forms of biological tissues and the values of B / A depend on the tissue composition and structural features.展开更多
This study explored the potential of polysaccharides from Actium lappa(ALPs)as natural wall materials for producing ALP-based nanoparticles to deliver poorly water-soluble oleanolic acid(OA)and ursolic acid(UA).Encaps...This study explored the potential of polysaccharides from Actium lappa(ALPs)as natural wall materials for producing ALP-based nanoparticles to deliver poorly water-soluble oleanolic acid(OA)and ursolic acid(UA).Encapsulating OA+UA with ALPs(ALP:OA+UA,50:1;OA:UA,1:1)changed the crystalline nature to a more amorphous state through hydrogen bonding and involving O-H/C-O/O-C-O groups.ALP-OA/UA nanoparticles had a particle size and zeta potential(in water)of 199.1 nm/-7.15 mV,with a narrow unimodal size distribution,and excellent pH,salt solution,temperature and storage stability.Compared with ALPs,ALPOA/UA nanoparticles showed enhanced anti-inflammatory activity(especially at a dose of 100μg/mL)in a CuSO-induced zebrafish inflammation model via down-regulating the NF-κB signalling pathway and gene expression of associated transcription factors and cytokines(TNF-α,IL-1βand IL-8).Therefore,ALP-based nanoparticles are natural and anti-inflammatory carriers for hydrophobic bioactive molecules.展开更多
The influence of thermal treatment on the structural features of mechano-synthesized fluorapatite-titania composite nanopowders was studied.A mixture of calcium and phosphate reagents was mixed with a certain amount o...The influence of thermal treatment on the structural features of mechano-synthesized fluorapatite-titania composite nanopowders was studied.A mixture of calcium and phosphate reagents was mixed with a certain amount of titania(20 wt%)and then was mechanically activated for 5 h,10 h and 15 h respectively.After that,the mechano-synthesized powders were annealed at 700℃for 2 h.The crystallite size of the composite nanopowders estimated from Williamson-Hall method was in good agreement with transmission electron microscopy(TEM)analysis.Scanning electron microscopy(SEM)/TEM images confirmed the formation of a cluster-like composite which was composed of ellipse-like nanoparticles with an average size of about 16±7 nm after 15 h of milling.During the milling process,large variations in mechanochemical behavior of the CaHPO_(4)-Ca(OH)_(2)-CaF2-TiO_(2) system were detected.After the beginning of milling,no trace of the composite was found due to the lack of sufficient time for the mechanical activation.When the mechanical activation time increased to 15 h,composite nanopowders with the crystallite size of around 21.66 nm were formed.During heating at 700℃,the recovery of crystallinity occurred and the fraction of crystalline phase reached a maximum around 88.79%for the 10-h milled sample.Results indicated that the structural features of the composite were strongly influenced by the subsequent annealing.展开更多
The 1°×1° distribution map of crustmantle structural ratio R for the lithosphere along the Longitudinal Seismic Belt of China has been compiled using computer based on the results of geophysical prospec...The 1°×1° distribution map of crustmantle structural ratio R for the lithosphere along the Longitudinal Seismic Belt of China has been compiled using computer based on the results of geophysical prospecting by previous researchers, and the latest results by the present authors. Based on this map, an insight into the structural features of the crustmantle assemblage along the Longitudinal Seismic Belt has been gained, while their relation to seismic activity and the distributions of geothermal flux and intracrustal high conductivitylow velocity layers, as well as their tectonic effect to seismicity have been discussed.展开更多
This work reports the structural feature and internal motion of one novel hyperbranching cluster system in dilution solution.The cluster system is composed of HB-PS_(300)-g-Pt BA_(45) hypergraft copolymer chains with ...This work reports the structural feature and internal motion of one novel hyperbranching cluster system in dilution solution.The cluster system is composed of HB-PS_(300)-g-Pt BA_(45) hypergraft copolymer chains with uniform subchain,high molar mass and low polydispersity(M_(w)=1.73×106 g/mol and<M_(w)/M_(n)>≈1.07),where HB-PS and Pt BA represent hyperbranched polystyrene core and poly(tert-butyl polyacrylate)graft,respectively.In the selective solvent of PS blocks(cyclohexane,T_(θ)=34.5℃),the aggregation kinetics and structural feature are found to be precisely tunable for assembled clusters by the aggregation temperature(11℃<T<17℃)and time(0 h<t<24 h).An interesting structural evolution kinetics is observed,namely,the fractal dimension(d_(f))of clusters is found to first increases and then decreases with t,eventually,it reaches a plateau value of d_(f)≈3.0,corresponds to a uniform spherical structure.By using dynamic light scattering(DLS)to monitor the number and strength of relaxation modes inΓ(q)withΓbeing the decay rate and q being the scattering vector,it is quantitatively revealed that the relaxation,intensity contribution and mode origin of internal motions of clusters are neither similar with previously reported cluster systems with high polydispersity,nor with the classical linear chain systems.In particular,in the broad range of 2.0<qR_(h)<6.0,we have observed that the reduced first cumulant[Γ^(*)=Γ(q)/(q^(3)k_(B)T/η_(0))]does not display an asymptotic behavior.Whereas,a better asymptotic behavior is observed by plottingΓ(q)/q^(4) versus qRh.For the first time,our observation provides direct evidence supporting that,for hyperbranching cluster system with low polydispersity and high local chain segment density,the hydrodynamic interaction is greatly weakened due to the enhanced hydrodynamic shielding effect.展开更多
Based on the difference in the density and content of kerogen and inorganic minerals, oil shale can be separatedinto different density fractions. The structural features of kerogens in Beipiao oil shale (a kind of typ...Based on the difference in the density and content of kerogen and inorganic minerals, oil shale can be separatedinto different density fractions. The structural features of kerogens in Beipiao oil shale (a kind of typical lowgrade oil shale resources) with densities of 1.8–1.9, 1.9–2.0 and 2.0–2.1 g/cm3 were studied. Combined withour previous study on the structural features of Longkou and Huadian oil shales (two kinds of high-grade oil shaleresources) with different densities, the relationship between the oil shale density and the structural features ofcorresponding kerogens was revealed from aromatic, aliphatic structures and heteroatom species. The resultsshow that with increasing the density, the content of minerals increases, whereas that of kerogen decreases. Withincreasing the density, the aliphaticity, average methylene chain length and average number of attachments oneach aromatic ring increase. Whereas, the aromaticity and average size of aromatic cluster are inversely proportional to the oil shale density. For Longkou, Huadian and Beipiao oil shales with different densities, thechange rules of aromatic and aliphatic structures with the density are similar, indicating that these change rulesare independent of the grade and origin of oil shale. The change rules of heteroatom species in Beipiao oil shaleare different from that of Longkou and Huadian oil shales.展开更多
In this paper, a series of Sb-doped and Bi-doped Cu_(2)Sn_(1-x)M_(x)Se_(3) samples(M = Sb, Bi) are prepared by vacuum melting combined with the spark plasma sintering process. The effects of different atomic doping am...In this paper, a series of Sb-doped and Bi-doped Cu_(2)Sn_(1-x)M_(x)Se_(3) samples(M = Sb, Bi) are prepared by vacuum melting combined with the spark plasma sintering process. The effects of different atomic doping amounts on their properties are discussed. Structural studies indicate that all obtained samples comprise a single Cu_(2)SnSe_(3) phase. Sb and Bi atoms are experimentally demonstrated to be efficient cation dopants for increasing the transport performance. Compared with that doping on the cation site,Bi doping is much more efficient in increasing the electron concentration of the Cu_(2)SnSe_(3) system. Ultimately, a high figure of merit of 0.36 is achieved in the Cu_(2)Sn_(0.94)Sb_(0.06) Se_(3) sample at 773 K due to the enhanced power factor and lowered lattice thermal conductivity,which are 1.73 times higher than those of the pure sample.Our results provide an efficient approach to enhance thermoelectric performance via other doping atoms, which could also be applied to copper-based chalcogenide materials.展开更多
A polysaccharide of Thea sinensis, TSA, has been isolated from the fresh leaves as a major fraction of polysaccharides. The mol. wt. was estimated to be 850,000 with [α]_D^(15)+ 25.5°(c=0.75, H_2O). The componen...A polysaccharide of Thea sinensis, TSA, has been isolated from the fresh leaves as a major fraction of polysaccharides. The mol. wt. was estimated to be 850,000 with [α]_D^(15)+ 25.5°(c=0.75, H_2O). The component sugars were determined as L-rhamnose, L-arabinose, and D-galactose in molar ratio of 0.54: 1.0: 0.94. The O-acetyl groups locating on galactose residues position 2 were also iden- tified and the content was 3.8％. The ^(13)C NMR spectrum and CrO_3 oxidation of TSA indicated the Rhamnose, Arabinose and Galactose to be in α-, α- and β-configurations, respectively. Me- thylation analysis, periodate oxidation, partial hydrolysis and ^(13) C NMR. spectrum showed that TSA. is a branched galactoarabinan.展开更多
The daily 1°× 1° data of the Aviation （AVN） model, the black body temperature （TBB） data of cloud top, and cloud images by geostationary meteorological satellite （GMS） are used to identify a dew-p...The daily 1°× 1° data of the Aviation （AVN） model, the black body temperature （TBB） data of cloud top, and cloud images by geostationary meteorological satellite （GMS） are used to identify a dew-point front near the periphery of the western Pacific subtropical high （WPSH）. The results clearly demonstrate the existence of the dew-point front, and its thermodynamic and dynamic structural characteristics are analyzed in detail. The dew-point front is a transitional belt between the moist southwest monsoon flow and the dry adiabatic sinking flow near the WPSH, manifested by a large horizontal moisture gradient in the mid-lower troposphere and conjugated with the mei-yu front to form a predominant double-front structure associated with intense rainfall in the mei-yu period. The mei-yu front is located between 30° and 35°N, vertically extends from the ground level to the upper level and shifts northward. The dew-point front is to the south of the mei-yu front and lies up against the periphery of the WPSH. Generally, it is located between 850 hPa and 500 hPa. On the dew-point front side, the southwesterly prevails at the lower level and the northeasterly at the upper level; this wind distribution is different from that on the mei-yu front side. Vertical ascending motion exists between the two fronts, and there are descending motions on the north side of the mei^yu front and on the south side of the dew-point front~ which form a secondary circulation. The dynamics of the double fronts also have some interesting features. At the lower level, positive vertical vorticity and obvious convergence between the two fronts are clearly identified. At the mid-lower level, negative local change of the divergence （corresponding to increasing convergence） is often embedded in the two fronts or against the mei-yu front. Most cloud clusters occur between the two fronts and propagate down stream in a wave-like manner.展开更多
This paper uses the ARW-WRF model to carry out a numerical simulation of a warm-sector heavy rainfall event over southern China on the 22-23 May, 2014. A composite analysis method was used to analyze the evolution pro...This paper uses the ARW-WRF model to carry out a numerical simulation of a warm-sector heavy rainfall event over southern China on the 22-23 May, 2014. A composite analysis method was used to analyze the evolution process and structural features of the convective cells on a convection line during this rainfall event. This analysis identified three stages:(1) Stage of activation: the equivalent potential temperature surfaces as lower layers start to bulge and form warm cells and weak vertical convective cloud towers which are subject to the impact of low-level warm moist updrafts in the rainfall sector;(2) Stage of development: the warm cells continue to bulge and form warm air columns and the convective cloud towers develop upwards becoming stronger as they rise;(3) Stage of maturity: the warm air columns start to connect with the stable layer in the upper air; the convective cloud tower will bend and tilt westward with each increasing in height, and the convection cell is characterized by a "crescent-shaped echo" above the 700 h Pa plane. During this stage the internal temperature of the cell is higher than the ambient temperature and the dynamic structural field is manifested as intensive vertical upward movement. The large-value centers of the northerly and westerly winds in the middle layer correspond to the warm moist center in the cells and the relatively cold center south of the warm air column. Further analysis shows that the formation of the "crescent-shaped" convective cell is associated with horizontal vorticity. Horizontal vorticity in the center and west of the warm cell experiences stronger cyclonic and anticyclonic shear transformation over time; this not only causes the original suborbicular cell echo shape to develop into a crescent-like shape, but also makes a convection line consisting of cells that develop to the northwest.展开更多
This study presents a transfer learning approach for discovering potential Mg-based superconductors utilizing a comprehensive target dataset.Initially,a large source dataset(Bandgap dataset)comprising approximately∼7...This study presents a transfer learning approach for discovering potential Mg-based superconductors utilizing a comprehensive target dataset.Initially,a large source dataset(Bandgap dataset)comprising approximately∼75k compounds is utilized for pretraining,followed by fine-tuning with a smaller Critical Temperature(T_(c))dataset containing∼300 compounds.Comparatively,there is a significant improvement in the performance of the transfer learning model over the traditional deep learning(DL)model in predicting Tc.Subsequently,the transfer learning model is applied to predict the properties of approximately 150k compounds.Predictions are validated computationally using density functional theory(DFT)calculations based on lattice dynamics-related theory.Moreover,to demonstrate the extended predictive capability of the transfer learning model for new materials,a pool of virtual compounds derived from prototype crystal structures from the Materials Project(MP)database is generated.T_(c) predictions are obtained for∼3600 virtual compounds,which underwent screening for electroneutrality and thermodynamic stability.An Extra Trees-based model is trained to utilize E_(hull)values to obtain thermodynamically stable materials,employing a dataset containing Ehull values for approximately 150k materials for training.Materials with Ehull values exceeding 5 meV/atom were filtered out,resulting in a refined list of potential Mg-based superconductors.This study showcases the effectiveness of transfer learning in predicting superconducting properties and highlights its potential for accelerating the discovery of Mg-based materials in the field of superconductivity.展开更多
The human pregnane X receptor（hPXR） plays a critical role in the metabolism, transport and clearance of xenobiotics in the liver and intestine. The hPXR can be activated by a structurally diverse of drugs to initiat...The human pregnane X receptor（hPXR） plays a critical role in the metabolism, transport and clearance of xenobiotics in the liver and intestine. The hPXR can be activated by a structurally diverse of drugs to initiate clinically relevant drug-drug interactions. In this article, in silico investigation was performed on a structurally diverse set of drugs to identify critical structural features greatly related to their agonist activity towards h PXR. Heuristic method（HM）-Best Subset Modeling（BSM） and HM-Polynomial Neural Networks（PNN） were utilized to develop the linear and non-linear quantitative structure-activity relationship models. The applicability domain（AD） of the models was assessed by Williams plot. Statistically reliable models with good predictive power and explain were achieved（for HM-BSM, r^2=0.881, q^2_（LOO）=0.797, q^2_（EXT）=0.674; for HM-PNN, r^2=0.882, q^2_（LOO）=0.856, q^2_（EXT）=0.655）. The developed models indicated that molecular aromatic and electric property, molecular weight and complexity may govern agonist activity of a structurally diverse set of drugs to h PXR.展开更多
The Deep Seismic Sounding( DSS) projects carried out from the 1970 s in the lower Yangtze region and its neighboring area were reviewed in this paper,then the basic wave group features of those wide angle reflection /...The Deep Seismic Sounding( DSS) projects carried out from the 1970 s in the lower Yangtze region and its neighboring area were reviewed in this paper,then the basic wave group features of those wide angle reflection / refraction record sections,and of the crustal structure are summarized. It shows that there were in total five clear wave groups on the record sections,which include the first arrival Pg,the reflection P1 from the bottom interface of the upper crust,the reflection P3 from the bottom interface of the middle crust,the strong reflection Pm from the Moho boundary,and the refraction Pn from uppermost mantle. In general,these phases are easily consistently traced and compared,despite some first arrivals being delayed or arriving earlier than normal due to the shallow sedimentary cover or bedrocks. In particular,in the Dabie Mountain region the seismic events of a few gathered shots always have weak reflection energy,are twisted,or exhibit disorganized waveforms, which could be attributed to the disruption variations of reflection depth,the broken Moho,and the discontinuity of the reflection boundary within crust. The regional crustal structures are composed of the upper,middle and lower crust,of which the middle and lower layers can be divided into two weak reflection ones. The crustal thickness of the North China and Yangtze platform are 30km- 36 km,and the Moho exhibits a flat geometry despite some local uplifts. The average pressure velocity in lower crust beneath this two tectonic area is 6. 7 ± 0. 3km / s. Nevertheless,beneath the Dabieshan area the crustal thickness is 32km- 41 km,the Moho bends down sharply andtakes an abrupt 4km- 7km dislocation in the vertical direction. The average pressure velocity in the lower crust beneath the Dabieshan area is 6. 8 ± 0. 2km / s.展开更多
基金funded by the Natural Science Foundation of Shandong Province, China (ZR2023MB049)the China Postdoctoral Science Foundation (2020M670483)the Science Foundation of Weifang University (2023BS11)。
文摘The catalyst layers(CLs) electrode is the key component of the membrane electrode assembly(MEA) in proton exchange membrane fuel cells(PEMFCs). Conventional electrodes for PEMFCs are composed of carbon-supported, ionomer, and Pt nanoparticles, all immersed together and sprayed with a micron-level thickness of CLs. They have a performance trade-off where increasing the Pt loading leads to higher performance of abundant triple-phase boundary areas but increases the electrode cost. Major challenges must be overcome before realizing its wide commercialization. Literature research revealed that it is impossible to achieve performance and durability targets with only high-performance catalysts, so the controllable design of CLs architecture in MEAs for PEMFCs must now be the top priority to meet industry goals. From this perspective, a 3D ordered electrode circumvents this issue with a support-free architecture and ultrathin thickness while reducing noble metal Pt loadings. Herein, we discuss the motivation in-depth and summarize the necessary CLs structural features for designing ultralow Pt loading electrodes. Critical issues that remain in progress for 3D ordered CLs must be studied and characterized. Furthermore, approaches for 3D ordered CLs architecture electrode development, involving material design, structure optimization, preparation technology, and characterization techniques, are summarized and are expected to be next-generation CLs for PEMFCs. Finally, the review concludes with perspectives on possible research directions of CL architecture to address the significant challenges in the future.
基金‘Research on Deep Structural Differences between Potential Oil-rich Depressions in Offshore basins of China Sea’from the scientific and technological project of CNOOC Research Institute Co.,Ltd.,under contract No.CCL2021RCPS0167KQN‘Resource Potential,Accumulation Mechanism and Breakthrough Direction of Potential Oil-rich Depressions in Offshore China Sea’,under contract No.220226220101+1 种基金the Project of China Geological Survey under contract No.DD20191003the National Natural Science Foundation of Shandong Province of China under contract No.ZR2022MD047。
文摘The Kyushu–Palau Ridge(KPR),an anti-S-shaped submarine highland at the center of the Philippine Sea Plate(PSP),is considered the residual arc of the Izu–Bonin–Mariana Island Arc,which retains key information about the cessation of the Western Philippine Basin(WPB)expansion and the Parece Vela Basin(PVB)breakup.Herein,using the new generation of satellite altimetry gravity data,high-precision seafloor topography data,and newly acquired ship-borne gravity data,the topographic and gravity characteristics of the KPR mid-southern section and adjacent region are depicted.The distribution characteristics of the faults were delineated using the normalized vertical derivative–total horizontal derivative method(NVDR-THDR)and the minimum curvature potential field separation method.The Moho depth and crustal thickness were inverted using the rapid inversion method for a double-interface model with depth constraints.Based on these results,the crust structure features in the KPR mid-southern section,and the“triangular”structure geological significance where the KPR and Central Basin Rift(CBR)of the WPB intersect are interpreted.The KPR crustal thickness is approximately 6–16 km,with a distinct discontinuity that is slightly thicker than the normal oceanic crust.The KPR mid-southern section crust structure was divided into four segments(S1–S4)from north to south,formed by the CBR eastward extension joint action and clockwise rotation of the PVB expansion axis and the Mindanao fault zone blocking effect.
基金Supported by the Fundamental Research Funds for the Central Universities(2017BSCXB27)the Research and the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX17_1507)
文摘Fushun oil shale(FOS) was subjected to thermal dissolution(TD) under different conditions. The results show that the optimal solvent, temperature, time, and ratio of solvent to FOS are ethanol, 300 °C, 2 h, and 5 ml·g^(-1),respectively and the corresponding yield of the soluble portion(SP) is 32.2%(daf), which is much higher than the oil content of FOS(ca. 6%), suggesting that TD in ethanol is an excellent way to extract organics from FOS.According to 3 direct analyses, aliphatic moieties in FOS are the most abundant followed by C\\O-containing moieties and each cluster in FOS has 3 conjugated aromatic rings on average with fewer substituents. According to the analysis with a gas chromatograph/mass spectrometer, alkanes are predominant in all the SPs. A number of alkenes were identified in the SPs from the TD, while none of the alkenes were detected in acetone-SP obtained at room temperature, implying that the TD can destroy the π-π and intertwining interactions between alkenes and macromolecular structures in FOS. Moreover, a small amount of alkyl-substituted phenols and alkoxysubstituted phenols were detected in ethanol-SP from the TD, which could be the products from ethanolyzing the macromolecular moiety of FOS.
基金Supported by the Natural Science Foundation of Fujian Province(2016J05068)High Level University Construction Projects of Fujian Agriculture and Forestry University(612014042)+2 种基金Science and Technology Development Foundation Project of Fujian Agriculture and Forestry University(KF2015101)Leading Talents Support Program of Science and Technology Innovation in Fujian Province(KRC16002A)Excellent Talents Support Program of Colleges and Universities in Fujian Province(JA14094)
文摘Fortunella margarita（Lour.） Swingle, commonly known as kumquat, is the smallest citrus fruit. It thrives in southeastern China and is widely cultivated and consumed in the world due to its multiple health benefits. It has been used as an important herbal medicine in traditional Chinese medicine and also as one of the most popular fruits. There are various kinds of bioactive compounds in F. margarita, such as polysaccharides, limonoids, essential oils, flavonoids, phenolic acids, vitamins, dietary fiber, etc. In addition, many studies have reported that these bioactive compounds can be used as antioxidant, antimicrobial, hypolipidemic, drosophila lure components in functional foods, pharmaceuticals and daily chemical products due to their biological activities. This review focuses on the structural features and biological activities of polysaccharides, limonoids, essential oils and flavonoids and other bioactive substances from F. margarita and their potential applications in food, daily chemical and pharmaceutical industries.
文摘Handwriting recognition is one of the most significant problems in pattern recognition,many studies have been proposed to improve this recognition of handwritten text for different languages.Yet,Fewer studies have been done for the Arabic language and the processing of its texts remains a particularly distinctive problem due to the variability of writing styles and the nature of Arabic scripts compared to other scripts.The present paper suggests a feature extraction technique for offlineArabic handwriting recognition.A handwriting recognition system for Arabic words using a few important structural features and based on a Radial Basis Function(RBF)neural networks is proposed.The methods of feature extraction are central to achieve high recognition performance.The proposed methodology relies on a feature extraction technique based on many structural characteristics extracted from the word skeleton(subwords,diacritics,loops,ascenders,and descenders).In order to reach our purpose,we built our own word database and the proposed system has been successfully tested on a handwriting database of Algerian city names(wilayas).Finally,a simple classifier based on the radial basis function neural network is presented to recognize certain words to verify the reliability of the proposed feature extraction.The experiments on some images of the benchmark IFN/ENIT database show that the proposed system improves recognition and the results obtained are indicative of the efficiency of our technique.
文摘Tropoje-Has ophiolitic massif of eastern Mirdita(Albania)ophiolitic belt,is a major source for metallurgical chromite ore in Albania.Massif consists of a thick mantle section of SSZ type,8-10 km thick and
基金This work was jointly supported by the project on the study of the formative mechanism and predictive theory of the significant weather disaster in China under Grant G 1998040907and supported by the project of Chinese Academy of Sciences under Grant KZC
文摘A new subtropical front near the periphery of the West Pacific subtropical anticyclone is found,which is never revealed in previous studies.The coupling of the subtropical front and Meiyu front forms a Meiyu front system (MFS) and is the most direct synoptic system for the Meiyu precipitation along the Mid-lower Reaches of Yangtze River (MRYR) in China.In this paper.The detailed structural features and cloud features of the MFS in 1998 and 1999 are analyzed,which manifests that the MFS is an objective phenomenon over the period of Meiyu along MRYR and the Southwest Japan.Generally.the subtropical front is mainly located between 850 hPa and 500 hPa.The moist southwest monsoon is transported in the passageway between the Meiyu front and the subtropical front.The vertical motion ascends in the passageway and descends on both sides of the MFS.forming the MFS's secondary circulation.A lower TBB band indicated that obvious convective activities are also located in the passageway of MFS.The horizontal wind of MFS is vertically asymmetric.
基金The project is supported by Natural Science Foundation of ChinaResearch Foundation for Doctor program by National Education Committee
文摘The Acoustic nonlinearity parameter is an important parameter in nonlinear acoustics. In this article, the nonlinearity parameter B / A of normal and eight kinds of pathological porcine liver tissues were measured by finite amplitude insert-substitution method. The mixture law for nonlinearity parameter is used to analyze and predict the volume fractions of the components in a given tissue. It was found that the nonlinearity parameter is sensitive to the pathological forms of biological tissues and the values of B / A depend on the tissue composition and structural features.
基金supported by the Shandong Provincial Natural Science Foundation of China(ZR2019BC100)Science,Education and Industry Integration Innovation Pilot Project of Qilu University of Technology(Shandong Academy of Sciences)(2020KJC-ZD10)Incubation Program of Youth Innovation in Shandong Province。
文摘This study explored the potential of polysaccharides from Actium lappa(ALPs)as natural wall materials for producing ALP-based nanoparticles to deliver poorly water-soluble oleanolic acid(OA)and ursolic acid(UA).Encapsulating OA+UA with ALPs(ALP:OA+UA,50:1;OA:UA,1:1)changed the crystalline nature to a more amorphous state through hydrogen bonding and involving O-H/C-O/O-C-O groups.ALP-OA/UA nanoparticles had a particle size and zeta potential(in water)of 199.1 nm/-7.15 mV,with a narrow unimodal size distribution,and excellent pH,salt solution,temperature and storage stability.Compared with ALPs,ALPOA/UA nanoparticles showed enhanced anti-inflammatory activity(especially at a dose of 100μg/mL)in a CuSO-induced zebrafish inflammation model via down-regulating the NF-κB signalling pathway and gene expression of associated transcription factors and cytokines(TNF-α,IL-1βand IL-8).Therefore,ALP-based nanoparticles are natural and anti-inflammatory carriers for hydrophobic bioactive molecules.
文摘The influence of thermal treatment on the structural features of mechano-synthesized fluorapatite-titania composite nanopowders was studied.A mixture of calcium and phosphate reagents was mixed with a certain amount of titania(20 wt%)and then was mechanically activated for 5 h,10 h and 15 h respectively.After that,the mechano-synthesized powders were annealed at 700℃for 2 h.The crystallite size of the composite nanopowders estimated from Williamson-Hall method was in good agreement with transmission electron microscopy(TEM)analysis.Scanning electron microscopy(SEM)/TEM images confirmed the formation of a cluster-like composite which was composed of ellipse-like nanoparticles with an average size of about 16±7 nm after 15 h of milling.During the milling process,large variations in mechanochemical behavior of the CaHPO_(4)-Ca(OH)_(2)-CaF2-TiO_(2) system were detected.After the beginning of milling,no trace of the composite was found due to the lack of sufficient time for the mechanical activation.When the mechanical activation time increased to 15 h,composite nanopowders with the crystallite size of around 21.66 nm were formed.During heating at 700℃,the recovery of crystallinity occurred and the fraction of crystalline phase reached a maximum around 88.79%for the 10-h milled sample.Results indicated that the structural features of the composite were strongly influenced by the subsequent annealing.
文摘The 1°×1° distribution map of crustmantle structural ratio R for the lithosphere along the Longitudinal Seismic Belt of China has been compiled using computer based on the results of geophysical prospecting by previous researchers, and the latest results by the present authors. Based on this map, an insight into the structural features of the crustmantle assemblage along the Longitudinal Seismic Belt has been gained, while their relation to seismic activity and the distributions of geothermal flux and intracrustal high conductivitylow velocity layers, as well as their tectonic effect to seismicity have been discussed.
基金financially supported by the National Natural Science Foundation of China(No.21973088)Shenzhen Science and Technology Program(Nos.RCYX20210706092101012 and ZDSYS20210623100800001)。
文摘This work reports the structural feature and internal motion of one novel hyperbranching cluster system in dilution solution.The cluster system is composed of HB-PS_(300)-g-Pt BA_(45) hypergraft copolymer chains with uniform subchain,high molar mass and low polydispersity(M_(w)=1.73×106 g/mol and<M_(w)/M_(n)>≈1.07),where HB-PS and Pt BA represent hyperbranched polystyrene core and poly(tert-butyl polyacrylate)graft,respectively.In the selective solvent of PS blocks(cyclohexane,T_(θ)=34.5℃),the aggregation kinetics and structural feature are found to be precisely tunable for assembled clusters by the aggregation temperature(11℃<T<17℃)and time(0 h<t<24 h).An interesting structural evolution kinetics is observed,namely,the fractal dimension(d_(f))of clusters is found to first increases and then decreases with t,eventually,it reaches a plateau value of d_(f)≈3.0,corresponds to a uniform spherical structure.By using dynamic light scattering(DLS)to monitor the number and strength of relaxation modes inΓ(q)withΓbeing the decay rate and q being the scattering vector,it is quantitatively revealed that the relaxation,intensity contribution and mode origin of internal motions of clusters are neither similar with previously reported cluster systems with high polydispersity,nor with the classical linear chain systems.In particular,in the broad range of 2.0<qR_(h)<6.0,we have observed that the reduced first cumulant[Γ^(*)=Γ(q)/(q^(3)k_(B)T/η_(0))]does not display an asymptotic behavior.Whereas,a better asymptotic behavior is observed by plottingΓ(q)/q^(4) versus qRh.For the first time,our observation provides direct evidence supporting that,for hyperbranching cluster system with low polydispersity and high local chain segment density,the hydrodynamic interaction is greatly weakened due to the enhanced hydrodynamic shielding effect.
基金The authors thank Dr.Chang Zhibing from China University of Mining&Technology(Beijing)for his kindly providing the oil shale samples.This work was supported by the National Natural Science Foundation of China(22008187)Ph.D.Research Initiation Fund of Xi’an Polytechnic University(107020401)the Natural Science Basic Research Program of Shaanxi(2021JQ-668).
文摘Based on the difference in the density and content of kerogen and inorganic minerals, oil shale can be separatedinto different density fractions. The structural features of kerogens in Beipiao oil shale (a kind of typical lowgrade oil shale resources) with densities of 1.8–1.9, 1.9–2.0 and 2.0–2.1 g/cm3 were studied. Combined withour previous study on the structural features of Longkou and Huadian oil shales (two kinds of high-grade oil shaleresources) with different densities, the relationship between the oil shale density and the structural features ofcorresponding kerogens was revealed from aromatic, aliphatic structures and heteroatom species. The resultsshow that with increasing the density, the content of minerals increases, whereas that of kerogen decreases. Withincreasing the density, the aliphaticity, average methylene chain length and average number of attachments oneach aromatic ring increase. Whereas, the aromaticity and average size of aromatic cluster are inversely proportional to the oil shale density. For Longkou, Huadian and Beipiao oil shales with different densities, thechange rules of aromatic and aliphatic structures with the density are similar, indicating that these change rulesare independent of the grade and origin of oil shale. The change rules of heteroatom species in Beipiao oil shaleare different from that of Longkou and Huadian oil shales.
基金financially supported by the National Key Research and Development Program of China(No.2019YFA0210003)the National Natural Science Foundation of China(Nos.11775163 and 11875208)。
文摘In this paper, a series of Sb-doped and Bi-doped Cu_(2)Sn_(1-x)M_(x)Se_(3) samples(M = Sb, Bi) are prepared by vacuum melting combined with the spark plasma sintering process. The effects of different atomic doping amounts on their properties are discussed. Structural studies indicate that all obtained samples comprise a single Cu_(2)SnSe_(3) phase. Sb and Bi atoms are experimentally demonstrated to be efficient cation dopants for increasing the transport performance. Compared with that doping on the cation site,Bi doping is much more efficient in increasing the electron concentration of the Cu_(2)SnSe_(3) system. Ultimately, a high figure of merit of 0.36 is achieved in the Cu_(2)Sn_(0.94)Sb_(0.06) Se_(3) sample at 773 K due to the enhanced power factor and lowered lattice thermal conductivity,which are 1.73 times higher than those of the pure sample.Our results provide an efficient approach to enhance thermoelectric performance via other doping atoms, which could also be applied to copper-based chalcogenide materials.
文摘A polysaccharide of Thea sinensis, TSA, has been isolated from the fresh leaves as a major fraction of polysaccharides. The mol. wt. was estimated to be 850,000 with [α]_D^(15)+ 25.5°(c=0.75, H_2O). The component sugars were determined as L-rhamnose, L-arabinose, and D-galactose in molar ratio of 0.54: 1.0: 0.94. The O-acetyl groups locating on galactose residues position 2 were also iden- tified and the content was 3.8％. The ^(13)C NMR spectrum and CrO_3 oxidation of TSA indicated the Rhamnose, Arabinose and Galactose to be in α-, α- and β-configurations, respectively. Me- thylation analysis, periodate oxidation, partial hydrolysis and ^(13) C NMR. spectrum showed that TSA. is a branched galactoarabinan.
基金projects of the National Natural Science Foundation of China(Grant Nos.40405007 , 40505009)the National Key Basic Research and Development Project of China(Grant No.2004CB418302) projects of Chinese Academy of Sciences (Nos.KZCX3-SW-225 and 2005r-2-16)
文摘The daily 1°× 1° data of the Aviation （AVN） model, the black body temperature （TBB） data of cloud top, and cloud images by geostationary meteorological satellite （GMS） are used to identify a dew-point front near the periphery of the western Pacific subtropical high （WPSH）. The results clearly demonstrate the existence of the dew-point front, and its thermodynamic and dynamic structural characteristics are analyzed in detail. The dew-point front is a transitional belt between the moist southwest monsoon flow and the dry adiabatic sinking flow near the WPSH, manifested by a large horizontal moisture gradient in the mid-lower troposphere and conjugated with the mei-yu front to form a predominant double-front structure associated with intense rainfall in the mei-yu period. The mei-yu front is located between 30° and 35°N, vertically extends from the ground level to the upper level and shifts northward. The dew-point front is to the south of the mei-yu front and lies up against the periphery of the WPSH. Generally, it is located between 850 hPa and 500 hPa. On the dew-point front side, the southwesterly prevails at the lower level and the northeasterly at the upper level; this wind distribution is different from that on the mei-yu front side. Vertical ascending motion exists between the two fronts, and there are descending motions on the north side of the mei^yu front and on the south side of the dew-point front~ which form a secondary circulation. The dynamics of the double fronts also have some interesting features. At the lower level, positive vertical vorticity and obvious convergence between the two fronts are clearly identified. At the mid-lower level, negative local change of the divergence （corresponding to increasing convergence） is often embedded in the two fronts or against the mei-yu front. Most cloud clusters occur between the two fronts and propagate down stream in a wave-like manner.
基金National Basic Research Program of China(Project 973:2013CB430103)National Natural Science Foundation of China(41530427)+1 种基金Chinese Academy of Meteorological Sciences(2015LASW-A07)State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences
文摘This paper uses the ARW-WRF model to carry out a numerical simulation of a warm-sector heavy rainfall event over southern China on the 22-23 May, 2014. A composite analysis method was used to analyze the evolution process and structural features of the convective cells on a convection line during this rainfall event. This analysis identified three stages:(1) Stage of activation: the equivalent potential temperature surfaces as lower layers start to bulge and form warm cells and weak vertical convective cloud towers which are subject to the impact of low-level warm moist updrafts in the rainfall sector;(2) Stage of development: the warm cells continue to bulge and form warm air columns and the convective cloud towers develop upwards becoming stronger as they rise;(3) Stage of maturity: the warm air columns start to connect with the stable layer in the upper air; the convective cloud tower will bend and tilt westward with each increasing in height, and the convection cell is characterized by a "crescent-shaped echo" above the 700 h Pa plane. During this stage the internal temperature of the cell is higher than the ambient temperature and the dynamic structural field is manifested as intensive vertical upward movement. The large-value centers of the northerly and westerly winds in the middle layer correspond to the warm moist center in the cells and the relatively cold center south of the warm air column. Further analysis shows that the formation of the "crescent-shaped" convective cell is associated with horizontal vorticity. Horizontal vorticity in the center and west of the warm cell experiences stronger cyclonic and anticyclonic shear transformation over time; this not only causes the original suborbicular cell echo shape to develop into a crescent-like shape, but also makes a convection line consisting of cells that develop to the northwest.
文摘This study presents a transfer learning approach for discovering potential Mg-based superconductors utilizing a comprehensive target dataset.Initially,a large source dataset(Bandgap dataset)comprising approximately∼75k compounds is utilized for pretraining,followed by fine-tuning with a smaller Critical Temperature(T_(c))dataset containing∼300 compounds.Comparatively,there is a significant improvement in the performance of the transfer learning model over the traditional deep learning(DL)model in predicting Tc.Subsequently,the transfer learning model is applied to predict the properties of approximately 150k compounds.Predictions are validated computationally using density functional theory(DFT)calculations based on lattice dynamics-related theory.Moreover,to demonstrate the extended predictive capability of the transfer learning model for new materials,a pool of virtual compounds derived from prototype crystal structures from the Materials Project(MP)database is generated.T_(c) predictions are obtained for∼3600 virtual compounds,which underwent screening for electroneutrality and thermodynamic stability.An Extra Trees-based model is trained to utilize E_(hull)values to obtain thermodynamically stable materials,employing a dataset containing Ehull values for approximately 150k materials for training.Materials with Ehull values exceeding 5 meV/atom were filtered out,resulting in a refined list of potential Mg-based superconductors.This study showcases the effectiveness of transfer learning in predicting superconducting properties and highlights its potential for accelerating the discovery of Mg-based materials in the field of superconductivity.
基金supported by grants from the Natural Science Research Project of Institution of Higher Education of Jiangsu Province(No.11KJB180006)National Natural Science Foundation of China(No.21277074 and No.81302458)
文摘The human pregnane X receptor（hPXR） plays a critical role in the metabolism, transport and clearance of xenobiotics in the liver and intestine. The hPXR can be activated by a structurally diverse of drugs to initiate clinically relevant drug-drug interactions. In this article, in silico investigation was performed on a structurally diverse set of drugs to identify critical structural features greatly related to their agonist activity towards h PXR. Heuristic method（HM）-Best Subset Modeling（BSM） and HM-Polynomial Neural Networks（PNN） were utilized to develop the linear and non-linear quantitative structure-activity relationship models. The applicability domain（AD） of the models was assessed by Williams plot. Statistically reliable models with good predictive power and explain were achieved（for HM-BSM, r^2=0.881, q^2_（LOO）=0.797, q^2_（EXT）=0.674; for HM-PNN, r^2=0.882, q^2_（LOO）=0.856, q^2_（EXT）=0.655）. The developed models indicated that molecular aromatic and electric property, molecular weight and complexity may govern agonist activity of a structurally diverse set of drugs to h PXR.
基金funded by the Special Public Welfare Industry Research of China Earthquake Administration(201408023)Academician Chen Yong Workstation Special Funds of Yunnan Province and Natural Science Foundation of China(41374062,41174075)
文摘The Deep Seismic Sounding( DSS) projects carried out from the 1970 s in the lower Yangtze region and its neighboring area were reviewed in this paper,then the basic wave group features of those wide angle reflection / refraction record sections,and of the crustal structure are summarized. It shows that there were in total five clear wave groups on the record sections,which include the first arrival Pg,the reflection P1 from the bottom interface of the upper crust,the reflection P3 from the bottom interface of the middle crust,the strong reflection Pm from the Moho boundary,and the refraction Pn from uppermost mantle. In general,these phases are easily consistently traced and compared,despite some first arrivals being delayed or arriving earlier than normal due to the shallow sedimentary cover or bedrocks. In particular,in the Dabie Mountain region the seismic events of a few gathered shots always have weak reflection energy,are twisted,or exhibit disorganized waveforms, which could be attributed to the disruption variations of reflection depth,the broken Moho,and the discontinuity of the reflection boundary within crust. The regional crustal structures are composed of the upper,middle and lower crust,of which the middle and lower layers can be divided into two weak reflection ones. The crustal thickness of the North China and Yangtze platform are 30km- 36 km,and the Moho exhibits a flat geometry despite some local uplifts. The average pressure velocity in lower crust beneath this two tectonic area is 6. 7 ± 0. 3km / s. Nevertheless,beneath the Dabieshan area the crustal thickness is 32km- 41 km,the Moho bends down sharply andtakes an abrupt 4km- 7km dislocation in the vertical direction. The average pressure velocity in the lower crust beneath the Dabieshan area is 6. 8 ± 0. 2km / s.
