最新刊期
卷 62 ， 期 1 ， 2023
- 摘要：The Pan-African event was a tectonic-thermal event initiated in Africa and later developed to the whole Gondwana ancient continent in the period of late Neoproterozoic to early Paleozoic with manifestations of suturing and collisions between plates and rejuvenating of ancient orogenic belts. After the Pan-African event， the Gondwana finally consolidated and formed， accompanying the breakup of the other continents on the globe at that time， the sea level rose and resulted in important unconformities on the earth in the Cambrian. Now the Pan-African records have been widely recognized in almost all the early Paleozoic orogens， the continents of China， Asia， and even in some parts of Europe.The Khanka， Jiamusi， and Bureya blocks in NE China have shown typical Pan-African features such as high-grade metamorphism and voluminous granites. Major orogenic belts， like the Tibetan， Central orogen， and Central Asian Orogen， and blocks such as the Cathaysia block，and Tarim blocks also demonstrate the Pan-African effects. Furthermore， the event might have affected all the major continents on the earth with multiple centers. The records of the Pan-African event in Eurasia might result from the initial breakup， marginal blocks， or orogens of Gondwana. The activities in the peri-Gondwana realm were generally confined to the middle or lower crust. The event was possible an intraplate process with extensional and shear activities， but not simply horizontal compression or accretion in the Gondwana sensu stricto. Granites or demonstration of the Pan-African event can be found in granitic gneisses of the early Neoproterozoic （Grenville period）. The event was followed by the stronger Caledonian movement. Most domains related to the Pan-African event can be subdivided into relatively stable regions and active zones which are alternatively distributed. They show contrasts in sedimentary formation， volcanism， un- or disconformity feature， deformation intensity， metamorphism type and grade， and magmatism activity. Pan-African orogeny has intimate relations with modern plate tectonic regime. Some Pan-African belts may be subducted， submerged， or exhumed in the plate movement， that is， some belts may be concealed or perished. Finally， the Pan-African belts may be the subsequent breakup positions of the continents， such as the formation of the Atlantic Ocean.关键词：Pan-African structure;Grenville structure;granites;unconformity/disconformity;continent breakup;Gondwana.
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发布时间：2023-11-01
Invited review
- 摘要：Based on the creep tests with lateral confinement and the close-range photogrammetry technology, the characteristics of particle breakage and creep of calcareous sand are continually captured and explored in this study. It is found that the creep deformation of calcareous sand increases with time which satisfies the Burgers model. The evolution of creep can be divided into two stages, the primary creep stage with the creep rate decreasing with time and followed by the steady creep stage with a relatively stable creep rate. The creep characteristics of calcareous sand are affected by stress conditions and particle breakage. The greater the axial creep stress, the greater the creep deformation and creep rate. Under low stress, the creep strain decreases with the particle size increasing due to the interlocking between the irregular particles; under relatively high stress, creep deformation and creep rate increase with the particle size increasing on account of the influence of particle crushing. Under the low stress (≤0.1 MPa), because of the interparticle locking in calcareous sand with irregular particle shape, the interparticle rearrangement is harder to occur, hence a smaller creep deformation is obtained for calcareous sand compared with siliceous sand. However, with the increase of stress, particles of calcareous sand begin to crush, and the creep deformation of calcareous sand increases and becomes more significant than that of siliceous sand. The particle crushing of calcareous sand increases with the rising of particle size and stress. The samples with particle sizes larger than 5 mm begin to break around 0.7 MPa of the vertical stress, and the creep deformation is provided by the rearrangement of intact particles and broken particles along cracks and pores.关键词：calcareous sand;particle breakage;creep;Burgers model;close-range photogrammetry
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发布时间：2023-11-01 - 摘要：The Quaternary aquitard of the Pearl River Delta （PRD） overlies the basal confined aquifer， and its hydrogeochemical evolution process has a decisive influence on the basal aquifer. In order to understand the formation and evolution of pore water in the aquitard of the Pearl River Delta， this study analyzes the major ions （K＋，Na＋，Ca2＋、Mg2＋，Cl-，SO4 2-，Br-）， hydrogeochemical parameters and mineral saturation index of pore water samples of the ZK01 borehole drilled in Zhongshan City. The results show that the salinity of pore water is relatively high and the TDS is between 4.42 and 30.47 g/L. The water chemistry of pore water is generally Cl-Na type， which is similar to seawater， and the concentrations of major ions tend to increase with the borehole depth. The Cl/Br， γ（Na/Cl） coefficients and Gibbs analysis show that the salinity of the aquitard pore water is mainly originated from seawater， and probably originated from Holocene seawater. Concentration of SO42－is mainly controlled by sulfate reduction in the aquitard and not affected by the precipitation of gypsum. Ca2＋and Na+ in shallow pore water are affected by cation exchange，which causes Na+ depletion and Ca2+ enrichment. NH4＋mainly exchanges with Mg2＋，resulting in the increase of NH4+ in pore water. K＋is mainly controlled by mixing and adsorption during pore water evolution， showing depletion characteristics. Based on the 14C dating data and taking the sedimentary environments， processes and rates under consideration， an one-dimensional solute transport model of the aquitard Cl－was established by using the hydrogeochemical simulation software PHREEQC. The simulation results show that the effective diffusion coefficient of the aquitard is about 6.0×10-11 m2/s，the vertical convection velocity can be neglected， and diffusion is the key mechanism for vertical solute transport in the PRD Quaternary aquitard.关键词：the Pearl River Delta;aquitard;pore water chemistry;solute transport
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发布时间：2023-11-01 - 摘要：Marine soft soils in the Shenzhen area show large foundation settlement and poor engineering properties after construction. To investigate the mechanism， we quantitatively analyzed the mineral composition and bound water characteristics by using X-ray diffraction and thermogravimetric tests. The results show that the bound water content of the as-built clay is about 3%， while the bound water content of the fine-grained clay sample is about 3.5%； The temperature required to completely remove the bound water is higher when the bound water content is higher. It indicates that soft soils with high clay mineral content tend to have high bound water content， which also leads to poor engineering properties.关键词：clay minerals;XRD;microstructure;thermal analysis
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发布时间：2023-11-01 - 摘要：Based on the monthly mean sea surface temperature（SST） data and the reanalysis data over the period of 1958-2018， we have investigated the interdecadal variation of the thermal response characteristics of the Indian Ocean， the South China Sea， and the Maritime Continent to the El Niño-Southern Oscillation（ENSO）. We have also investigated the interdecadal variation of the physical process for the circulation response features over the subtropical northwestern Pacific Ocean to ENSO events. During the evolution of the ENSO events， the SST in different areas of the tropical Indian Ocean and adjacent waters presents various features in terms of both maximum lag-response and duration of prominent lag-response to the SST anomalies in the equatorial central-eastern Pacific. The prominent lag-response of the SST in the tropical northern Indian Ocean， the Maritime Continent， and the South China Sea can last until the following summer of ENSO. Both the evolution features of the ENSO events and the lag response features of SST in the tropical Indian Ocean and the Maritime Continent to ENSO experienced obvious interdecadal changes in the early 1980s and early 2000s. Compared with the first and the third periods， the duration and strength of ENSO events were longer and stronger in the second period， respectively， accompanied by slower significant response of the SST in the tropical southern and northern Indian Oceans. The SST in the Maritime Continent experienced noticeable interdecadal changes alternatively in the significant lag-response and the less significant lag-response to ENSO， with a longer duration of the noteworthy response in the last period than in the first one. The impact process of the ENSO on the summer circulation over the subtropical East Asia， via the lag-response of the SST in the tropical Indian Ocean and adjacent waters， also shows interdecadal changes. The SST in the Maritime Continent， the tropical northern Indian Ocean and the equatorial central-eastern Pacific can be recognized as the key factors in different periods， which may induce the anomalous summer circulation over the subtropical East Asia， and then further affect the summer climate in East Asia.关键词：ENSO;sea surface temperature;Indian Ocean;response time;interdecadal change
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发布时间：2023-11-01 - 摘要：Soil organic carbon is one of the important indicators for soil nutrient and quality assessment. At the small watershed scale, studying the horizontal and vertical distribution characteristics of soil organic carbon and its main influencing factors is of great significance to the scientific management of landuse. Taking the small watershed of Lujing Reservoir in Yingde city, northern Guangdong Province as the research object, collecting soils of four main landuse types including Camellia sinensis gardens (Yinghong12 (Cs12) and Yinghong9 (Cs9)), Eucalyptus robusta forests (Er),Pinus massoniana forests (Pm) and secondary forests (SF) in the watershed. Soil particle size composition, pH, electrical conductivity (EC), soil organic carbon (SOC),particulate organic carbon (POC), total nitrogen (TN),carbon to nitrogen ratio (C/N), and soil carbon and nitrogen isotope values(δ13C, δ15N) were measured, combined with the slope and aspect of the sampling site and the quality and thickness of litter, redundant analysis was conducted to explore the main influencing factors of SOC and POC content. The results show that: 1) The soil pH in the Lujing Reservoir watershed is between 4.2 and 5.8, and soil acidification occurs. The soil texture is silt loamy. The difference in soil pH, EC, TN, T/N, and δ13C, δ15N between different landuse types is significant (P<0.05); 2) In 0~40 cm depth, the SOC and POC content decrease with the increase of the depth, and the variation ranges are 0.5%~1.3% and 1.2~3.9 g/kg, respectively, showing obvious surface aggregation. However, there is no significant difference in SOC and POC content between the different landuse types selected; 3) The soil , topographic and environmental factors selected in this study can explain 78.1% of the variation of SOC and POC. Among them, C/N, TN, pH, soil depth and bulk density(BD) are the main factors affecting the changes in SOC and POC content in this small watershed. SOC and POC were significantly positively correlated with C/N and TN, while significantly negatively correlated with soil pH, soil depth, and BD.关键词：soil organic carbon;landuse types;carbon and nitrogen isotope;redundancy analysis;Lujing reservoir watershed
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发布时间：2023-11-01 - 摘要：China is the most seriously affected area by typhoons. It is of great significance for the theory and practice of zonal disaster risk prevention to carry out a systematic risk assessment of typhoon disasters and regional law summary and regionalization research. Based on the regional disaster system theory, we systematically evaluate the population and economic risk of typhoon disasters in Guangdong Province and express the results using a geo-graph method of the return period, to support the future work of typhoon disaster risk regionalization. In the model, typhoon hazards include wind, heavy rain, and flood. The evaluation model includes three factors: typhoon hazard intensity, the social vulnerability of the population and economic victims, and the extent of exposure. The scenarios include 5-year, 10-year, 20-year, 50-year, and 100-year return periods. The results show: 1) the hazard intensity decreases gradually from coastal to inland for each scenario, i.e., intensive hazards mainly concentrate in coastal areas and inland areas along rivers. 2) the high vulnerability is mainly distributed in urban areas of the Pearl River Delta, East, North, and West Guangdong. 3) the high exposure is mainly concentrated in the Pearl River Delta, East, and West Guangdong cities. 4) the risk gradually decreases from coastal to inland, in five scenarios high-risk areas are concentrated in the Pearl River Delta, and the secondary high-level centers are in the Chaozhou, Shantou urban area in eastern Guangdong, and the Zhanjiang, Maoming urban area in western Guangdong. These multi-scenario and systematic results could be the basis of the following research on the regionalization of natural disaster risk.关键词：typhoon disaster;risk assessment;population and economic risk;risk regionalization;Guangdong province
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发布时间：2023-11-01 - 摘要：Migrant workers moving to urbanized areas constitute a floating labor pool that provides flexible and cheap labor for urbanization processes. The Thirteenth National People's Congress of the People's Republic of China proposed the "acceleration of citizenization of rural migrant workers". Promoting the citizenization of migrant workers has always been a focus of the government and academia as well as a fundamental part of China's new urbanization strategy. Based on the questionnaire data of 1 270 migrant workers of the Pearl River Delta in 2017, this paper adopts the multinomial Logistic regression analysis to explore the residential choice and influencing factors among four types of migrant workers' families, which are childless family (I), parents and minor children combined family (Ⅱ),unmarried children and their parents combined family (Ⅲ), and empty-nest family (Ⅳ), from the perspective of the family life cycle. The results show that: 1) The average age, the length of residence, the level of education, the average monthly income, and the per capita living area of the four types of families show regular differentiation. 2) The residential choice of 4 types of families is mainly in urban villages; Types I and IV prefer to select factory dormitories and affordable housing communities, respectively, while types II and III prefer to select commodity housing communities. 3) The main influencing factors of the residential choice of migrant workers in the Pearl River Delta are family type, individual factor, rural factor, migration factor, and location factor. Based on the results of this study, we put forward community-based policy suggestions for citizenization strategy.关键词：migrant workers;residential choice;influencing factors;family life cycle;the Pearl River Delta
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发布时间：2023-11-01 - 摘要：The second-by-second vehicle license plate record data in 2017 was obtained through the Foshan video bayonet. Taking “Foshan First Ring Road” as the boundary， the hourly-scale different vehicle types of non-local vehicles inside and outside the region， the travel and technology parameters time-varying characteristics of road types are studied.The results show that： （1） The average daily travel volume of non-local vehicles in Foshan accounts for 24.11% of the total vehicles in the city， which is similar to the proportion of non-local vehicles （23%） in large provincial capital cities. Among them， the traffic volume of heavy and light vehicles is significantly different inside and outside the “Foshan First Ring Road” （over 50%）. （2） Vehicles from other places inside and outside the province are mainly from Guangzhou， Zhaoqing， Guangxi and Zhejiang， and are mainly distributed on the Guangfo connecting channel. The emission standards of non-local trucks and trucks in the province are mainly China IV （38.9%~44.6%）， and the fuel type is mainly diesel （78.0%~78.4%）. （3） From the point of view of hourly traffic flow， the hourly traffic volume of non-local vehicles inside the “Foshan First Ring Road” is higher than that outside the “Foshan First Ring Road”. In the daytime， the total traffic volume of non-local vehicles， and the traffic volume of non-local vehicles distributed according to different vehice types are both about 3 times that of the night-time. From the perspective of the emission standards of non-local vehicles in the province， the hourly traffic volume of China IV vehicle is the highest； at the same time， non-local vehicles mainly appear on expressways and national and provincial roads.关键词：city traffic;travel and technical parameters;video bayonet;non-local vehicles;temporal and spatial distribution
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发布时间：2023-11-01 - 摘要：Five groups of silicon wafers were cut from a commercial solar-grade boron-doped Czochralski silicon （Cz-Si） ingot from top to bottom with a certain distance， and made into PERC （passivated emitter and rear cell） solar cells by using the standard industrial process. Then， as-prepared PERC solar cells were treated by dark annealing （200 ℃， 30 min）， the 1st LID （45 ℃， 1 sun， 12 h）， electric-injection regeneration （175 ℃， 18 A， 30 min） and the 2nd LID （45 ℃， 1 sun， 12 h） in order， and the changes of performance during the process were measured. The results show that the LID （light induced degradation） and regeneration of the PERC solar cells are dominated by those of B-O defects， while dissociation of Fe-B pairs plays a secondary role. The relative degradation rate of 7.03%~9.69% in efficiency during the 1st LID results from the LID caused by B-O defects and the dissociation of Fe-B pairs， while the relative degradation rate of 0.43%~0.81% in efficiency during 2nd LID is solely caused by the dissociation of Fe-B pairs. B-O defects inside PERC solar cells can be completely passivated by the electric injection regeneration， and the passivated B-O defects are stable under the conditions of 2nd LID. PERC solar cells made from the middle of the Czochralski silicon ingot have higher efficiency and open circuit voltage and lower relative degradation rate. In addition， only the spectral response of PERC solar cells in medium and long wavelength range is affected by the LID and regeneration treatment.关键词：PERC solar cell;light induced degradation（LID）;electrical-injection regeneration;B-O defect
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发布时间：2023-11-01 - 摘要：A wide distributed moss species Hypnum plumaeforme was selected as a research material to investigate the temporal dynamics of its responses to mild low temperature （LT）. The results showed that LT induced a significant increase in the content of malondialdehyde at 12 h， and then the content decreased to the initial level， while H2O2 content fluctuated during the experiment period. LT inhibited the activity of superoxide dismutase，but the activities of catalase and guaiacol peroxidase in LT samples were higher than in control generally. Soluble sugars were accumulated after 84h of LT treatment， while the content of proline was continuously decreased during the treatment. The contents of several hormones including abscisic acid， ethylene， salicylic acid and jasmonates were accumulated in the LT treated at 12 h， but decreased at 36 h， and then increased again gradually and maintained at relatively high levels. These results suggested that the hormones were actively involved in the anti-stress regulation， while the compatible substances respond to LT were in a relatively slower efficiency.关键词：Hypnum plumaeforme;low temperature;physiological responses;time dynamic
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发布时间：2023-11-01 - 摘要：The secondary metabolites of endophytic fungus Alternaria sp. SK6YW3L were studied. The fungus was isolated from the fresh fruit of mangrove plant Sonneratia apetala collected from Guangxi Shankou Mangrove Nature Reserve. The strain was fermented and cultured with 3% salinity rice medium， and then subjected to silica gel column chromatography， semi-preparative HPLC， Sephadex LH-20， ODS and recrystallization. Thirteen anthraquinones including 7-acetyl-1，3，6-trihydroxyanthracene-9，10-dione （1）， （11S）-1，3，6-trihydroxy-7-（1-hydroxyethyl）anthracene-9，10-dione （2）， 7-O-demethyl-6-deoxybostrycoidin （3）， altersolanol A （4）， dactylariol （5）， altersolanol B （6）， emodin （7）， emodin-3-methyl ether （8）， 6-hydroxy -aloeemodin （9）， anthraquinone A （10）， 1，5-dihydroxy-7-methoxy-2- methylanthracene-9，10-dione （11）， alterporriol N （12） and alterporriol A （13）， were identified using modern spectroscopy techniques such as 1D， 2D NMR and MS， and then comparing with literature data. The single crystal structure of compounds 1 and 4 were analyzed by single-crystal X-Ray diffraction experiment using CuKα radiation. Among them， compound 1 was obtained as a new single crystal， and the absolute configuration of compound 4 was determined to be 5R， 6S， 7R， 8S. The absolute configurations of other compounds were determined by comparing optical rotation and CD data. In the bioactivity assay， compounds 1-3 exhibited α-glucosidase inhibitory activity with IC50 values of （210.1 ± 1.2）， （125.8 ± 1.5） and （68.7 ± 1.3） μmol/L， respectively.关键词：mangrove;endophytic fungus;Alternaria sp.;secondary metabolite;anthraquinones
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发布时间：2023-11-01 - 摘要：Under solvothermal conditions， an imidazole derivative 4，4′-bis（2-methyl-1H-imidazol-1-yl）-1，1′-biphenyl （4，4′-BMIB）， 2，5-dimethoxyterephthalic acid （H2DTA） and Zn（Ⅱ） ion were used to construct a metal-organic framework （MOF） with fluorescent properties， namely ［Zn（DTA）（4，4′-BMIB）］n（MOF 1）. It was characterized by X-Ray single crystal diffraction， X-Ray powder diffraction， infrared spectroscopy and thermogravimetric analysis. The results showed that MOF 1 was a four connected frame structure with topological symbol （63·103）. In addition， MOF 1 has good fluorescence and can realize highly sensitive and selective fluorescence quenching detection of iron ions in aqueous solution.关键词：metal-organic frameworks （MOFs）;fluorescence sensor;Fe3+ ions;imidazole derivatives;2，5-dimethoxyterephthalic acid
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发布时间：2023-11-01 - 摘要：The chiral flip mechanism of S-α-alanine（S-α-Ala） and tetravalent selenium（Se（Ⅳ）） complexes（S-α-Ala·Se（Ⅳ）） was studied by means of M06 and MN15 methods based on density functional theory and SMD model method of polarized continuum. The study of reaction channels shows that S-α-Ala·Se（Ⅳ） can be transferred when the carbonyl O atom as the only medium of α-H proton； the proton transfers to α-C from amino group N after the α-H proton is transferred to carbonyl O atom； after the proton of protonated amino transfers to carbonyl O atom， α-H proton achieves chiral flip in three channels with amino group N as the medium of protolysis. Investigation on the potential energy surface shows that the third reaction channel has the most advantage， the free energy barrier is 227.6 kJ/mol under the effect of recessive solvent， it comes from the transient state of the proton moving from amino group N to α-C； Under the dominant solvent effect， the free energy barrier is 155.6 kJ/mol， it comes from the transient state of the proton moving from protonated amino group N to carbonyl O atom. The results show that chiral α-Ala·Se（Ⅳ） is difficult to racemize in water-liquid phase， and thus it is relatively safe to be used to supply α-Ala and Se（Ⅳ） for life simultaneously.关键词：α-alanine;tetravalent selenium;density functional theory;chiral flip;energy barrier
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发布时间：2023-11-01 - 摘要：Based on the successful synthesis of novel hierarchical porous polymer （nHPP）， the micro-， nano-structure of nHPP was characterized， the effect of Friedel-Crafts crosslinking conditions on the porous structure was studied in detail， and the liquid phase adsorption performance of nHPP toward organic dye molecules in water was further investigated. The experimental results showed that nHPP presented a three-dimensional nano-network structure composed of hollow polymeric nanospheres stacked with each other， with a size of 154 nm for the hollow polymeric nanosphere network unit， and a shell thickness of about 7 nm. The polymer skeleton contains a large number of micropores， and the meso/macro pore structure derives from the stacking of polymeric nanospheres and the template cavities， thus forming a porous structure with hierarchical distribution of micro-， meso- and macropores. By controlling the reaction conditions， the BET（Brunauer-Emmett-Teller） specific surface area， microporous specific surface area， total pore volume and microporous pore volume can be well adjusted. The abundant and hierarchical porous structure of nHPP facilitates decent adsorption performance toward Congo red in water. The initial stage of the adsorption process is mainly controlled by the diffusion of Congo red in the external liquid film of the adsorbent， and the later stage is mainly controlled by the diffusion of Congo red in the particles in the internal pores of the adsorbent.关键词：novel hierarchical porous polymer;Friedel-Crafts crosslinking;structural control;liquid-phase adsorption
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发布时间：2023-11-01 - 摘要：The outage performance of the cognitive relay networks is analyzed based on simultaneous wireless information and power transfer （SWIPT） and non-orthogonal multiple access （NOMA）. The analytical expressions of overall outage probability and asymptotic expressions on high signal-to-noise ratio （SNR） are derived for the direct link transmission mode and the two-stage communication transmission mode. The analytical expressions are validated by Monte-Carlo simulations. The simulation results demonstrate that the outage performance is improved by through the direct link transmission. Furthermore， compared with the conventional cognitive relay networks with orthogonal multiple access （OMA）， superior outage performance and high energy efficiency are achieved for the cognitive relay networks based on SWIPT-NOMA.关键词：simultaneous wireless information and power transfer （SWIPT）;non-orthogonal multiple access （NOMA）;cognitive relay networks;outage performance;diversity gain
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发布时间：2023-11-01 - 摘要：In the theory of Markov decision processes， the randomness of the objective stems from not only the stochasticity of the process but also the randomnesses of the one-step reward and the policy. When the optimality criterion concerns only the risk-neutral expectation of the objective， the reward （function） simplification will not affect the optimization result. However， the simplification will change the stochastic reward sequence， which results in a modification to a risk-sensitive objective， i.e.， a risk measure. Since some theoretical methods may require a simple reward function in a practical environment with a complicated one， to bridge this gap， we propose a technique termed state augmentation transformation， which preserves the stochastic reward sequence in a transformed process with a reward function in a simple form. Taking three classical risk measures （variance， exponential utility， and conditional value at risk） for example， the numerical experiment shows that the state augmentation transformation keeps the risk measures intact， while the reward simplification fails.关键词：Markov decision process;state augmentation transformation;risk;reward simplification
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发布时间：2023-11-01
Research articles
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