This article addresses where ruts are likely to occur during in-field forest operations. This was done by inspecting high-resolution surface images across New Brunswick (NB) and elsewhere to mark where ruts have (1) a...This article addresses where ruts are likely to occur during in-field forest operations. This was done by inspecting high-resolution surface images across New Brunswick (NB) and elsewhere to mark where ruts have (1) and have not (0) occurred in harvested cutblocks. This marking revealed 1) where off-road operations were likely done on moist to wet and unfrozen soils;and 2) whether the ruts so incurred were water-logged at the time of imaging. Through geospatial processing of the NB-wide digital elevation model (DEM, available at 1 m resolution), the following attributes were added to each of the marked rut and no-rut locations: 1) the cartographic depth-to-water (DTW) as referenced to the nearest flow channels with >1 and >4 ha upslope flow accumulation areas (FA);2) the topographic position index (TPI) in reference to the mean annulus elevation 50 m away from each DEM cell;3) mean slope and curvatures within each cell-surrounding 10-m circle;4) the terrain wetness index (TWI);5) soil association type according to the NB forest soil map, adjusted for NB’s most recent hydrographic network delineations for waterbodies and wetlands. Subjecting these data to logistic regression analysis revealed that image-located off-road rutting occurred at about 90% probability in water-accumulating zones where TPI is <0 m and DTW is <1 m. Using slope, curvature, TWI, and soil type as additional rut occurrence predictors did not affect this zonation significantly.展开更多
ObjectiveThis study aims to characterize the occurrences and interior structural features of botryoidal structures from the Sinian Dengying Formation in the Sichuan Basin of Southwestern China, and to shed light on th...ObjectiveThis study aims to characterize the occurrences and interior structural features of botryoidal structures from the Sinian Dengying Formation in the Sichuan Basin of Southwestern China, and to shed light on their formation mechanism.展开更多
It is known that the formation of oceanic crust occurs in different geodynamic settings,accompanying by the emergence of mantle-magmatic ophiolite complexes having a distinctive properties.In the process of mantle-cru...It is known that the formation of oceanic crust occurs in different geodynamic settings,accompanying by the emergence of mantle-magmatic ophiolite complexes having a distinctive properties.In the process of mantle-crustal evolution of the ophiolites are undergoing significant changes with the formation of peculiar(on structure and composition)rocks,sometimes with unusual mineral paragenesis.The presence of such rocks in mélange tectonic zones greatly complicates to determine their origin.In the Ural folded belt(length more than 2,000 km)separating the East European Platform and the West Siberian sedimentary basin,ophiolites are widespread forming a chain of mafic-ultramafic massifs(Fig.1)located in the allochthonous position with mélange at the bottom(Puchkov,2013).With the Urals ophiolites are associated occurrences of eclogites,jadeites,ruby and other rocks of unclear nature,sometimes regarded as potentially diamondiferous.Such formations of unclear genesis include the associating with ophiolites metabasites of higher alkalinity composing the body in the mantle peridotites of the mélange Main Uralian Fault(MUF)zone(Shmelev,2005).By this time they are determined in different parts of the fault zone,but most completely are known in the Sub Polar Urals,where are distinguished under the name of Sertynya alkaline-ultramafic complex,which is located just 25 km east of Hartes kimberlitic complex(Fig.1).Formally,its affiliation to diamond-bearing associations is confirmed by finding of grains and fragments of natural diamond in the weathering crust.A detailed study of the rock complexes shows that in reality they have a polygenic nature,combine theelements of proper magmatic and fluidizate-explosive formations,the appearance of which was interfaced with the processes at the slab-mantle wedge boundary in subduction zones.Polygenic nature of the rocks is reflected in the existence of three interrelated structural-geological units:(1)bodies and dikes of uniformmetadiabasesanddensefine-grainedmetadolerites(lamprophyres),(2)fluidal-brecciated dolerites('tuff breccias')and(3)structural weathering crust with angular or rounded fragments(blocks)of metadolerites and serpentinites.The rocks have experienced rodingitization and permeated with net of veins a vesuvianite composition.The host peridotite matrix(harzburgites and dunites)has undergone serpentinizationandchloritization.Structural relationships give grounds for distinguishing in the history of the complex formation the magmatic proper(dolerite dyke and lamprophyre intrusion)and infiltration fluidizate-explosive(metasomatic transformation of dolerite)stages.Peculiarities of petrography and mineralogy of rock complexes does not allow to compare them with lamproites and kimberlites.Metadiabases demonstrate relics of ophitic structure,as primary paragenesis is completely replaced by aggregate of chlorite,zoisite and leucoxene.Dolerites(lamprophyres)have a uniform fine-grained or porphyry structure with phenocrysts of clinopyroxene,brown amphibole and leucoxene(sphene),which are immersed in a fine-scaly aggregate of light green mica.In the rocks amphibole,garnet and vesuvian are present.Clinopyroxene corresponds to augite with moderate content of titanium and alumina(up to 3.5wt.%),showing a normal magmatic zonation in composition.Mica previously wrongly called as phlogopite,actually has an extremely ferrous composition and corresponds to biotite(annite).Amphibole is presented by magmatic titaniferous tschermakite hornblende and metamorphic(bluish)variety of sodium-calcium composition(taramite).Garnet is presented by exceptionally grossular of rodingite type.Mineralogy of weathering crust reveals similar features,but in the samples it is marked the presence of muscovite,orthoclase and weakly ferrous diopside.An important feature of the weathering crust is the presence of shear surfaces on minerals,resulting in fracturing due to internal stress,confirming the explosive nature of protolith.The bulk chemical composition of rocks is characterized by significant variations in the content of silica(30-46 wt.%)and alkalis(0-6.5 wt.%).These metabasites have consistently a low magnesia number and high titanium oxide content(1.5-3.0 wt.%).Side by side with these are been established the uniform slope REE distribution trends similar to the trend of oceanic basalts N-MORB type(Fig.2).The level of trace element compositions does not depend on variations in the alkalinity of the rocks,but clearly correlates with the titanium content.Unlike them the Hartes kimberlites demonstrate the distribution with deficit of HREE,andthe level of the elements content is correlated with the alkalinity of rocks(Mahotkin et al.,1998).Another important geochemical feature of the Sertynya complex rocks is a regular behavior of the mobile LILE elements(Cs,Rb,Ba,K).In the varieties of rocks with mica enriched by alkalis,it is recorded extremely high level of LILE,exceeding the level of contents in N-MORB basalts at 10-10000 times!In the metabasites varieties with low level of alkalinity,LILE content is sharply(except Cs)reduced to minimum values(Fig.2).The observed pattern of the element distribution is undoubtedly the result of postmagmatic fluid-metasomatic alteration of the original rocks.Tectonic position and the primary composition characteristics of the metadolerites give reason to consider them as fragments of the ophiolite sheeted dike complex(Shmelev,2005).The famous dike complexes in the ophiolite massifs of the MUF zone(east of mélange)belong to suprasubduction formations of Paleozoic age.However the obtained mainly ancient U-Pb zircon dating(up to Archean inclusive)for metadolerites of the Sertynya complex,make it possible to assume its Vendian-Early Cambrian(530-617 Ma)age.It permits to compare the Sertynya metabasites with the Vendian metaophiolites of the MUF zone in the Middle Urals(Petrov et al.,2010).It is noteworthy that similar age datings(520-550 Ma)are also established for kimberlites of the Hartes complex located to the west of ophiolites.Therefore,thepresenceofthe Vendian-Cambrian ophiolite of MOR-type in the MUF mélange zone,'changing'to the east of Ordovician ophiolites SSZ-type,seems quite possible.The obtained data allow to suggest an original interpretation of nature of the Urals fluidizate-explosive formations considering the process specifics in the subduction zones(Bebout and Barton,2002).Accordingto this model,the pre-Ordovician(?)oceanic crust has undergone transformations and deformations on the slab-mantle wedge boundary during the subduction.As a result of slab dehydration it occurred a flow of aqueous fluids,which were enriched with the extracted from sedimentary rocks the LILE elements and percolated through the mantle substrate with dolerite dyke complex.Interaction with them led to the formation of chlorite-zoisite and/or mica(biotite-bearing)fluidizates and in the presence of a gas phase-fluidizate-explosive breccias with subsequent development of weathering crust.In the surrounding peridotites an explosive process is marked by the formation of pseudokimberlite breccias.Fluidized-explosive occurrences in mantle peridotites of mélange zones should be considered as indicators of the subduction slab-mantle interaction at relatively shallow levels involving enriched LILE fluids(without melts participation),rising as the front from the subduction zone.In this interpretation,there is no need toappealtothealkaline-ultramaficor lamproit-kimberlite hypothesis of the genesis of these formations,however,the question of their potential diamondiferous remains to be open.The proposed interpretation of the fluidizate-explosive occurrences makes it possible to comprehendthat in reality the mélange is a complex formation with signs of not onlycollisional(as usually is considered),but also of earlier subduction events.展开更多
Kakheti and Tusheti regions(Eastern Graeter Caucasus),of the Georgia Republic are mainly underlain by highly deformed Lower-Middle Jurassic shales,sandstones,and volcaniclastic rocks,intruded by numerous intrusive bod...Kakheti and Tusheti regions(Eastern Graeter Caucasus),of the Georgia Republic are mainly underlain by highly deformed Lower-Middle Jurassic shales,sandstones,and volcaniclastic rocks,intruded by numerous intrusive bodies of various compositions.All units contain a variety of ore mineral deposit types and their surrounding zones of hydrothermal alteration.Continued geological and metallogenic researches in the past 30 years have led to important new information regarding the evolution of this region.Three main stages of magmatic activity are now clearly distinguished.Oldest magmatism comprises Early Jurassic events,related to extensional tectonism,which ranged from rhyolitic,through dacitic and andesitic,and to basaltic magma.Additional extensional processes(in Bajocian)were characterized by intrusion of a gabbro and diorite dike system into recently deposited late Early Jurassic-early Middle Jurassic formations.The final magmatic event was associated with Middle Jurassic folding and uplift during which multiphase diorite plutons were emplaced.Related intense hydrothermal activity was responsible for important polymetallic mineralization,with more than 100 recognized outcropping ore occurrences.A detailed study of 11 of these ore occurrences has indicated anomalous concentrations of gold,thorium,yttrium,cobalt,cadmium,and bismuth.In addition,several new and potentially significant ore mineral occurrences were discovered.展开更多
The eastern part of the Caucasus orogen,termed the Georgian segment,is mainly underlain by highly deformed Lower-Middle Jurassic shales,sandstones,and volcaniclastic rocks,and cut by numerous intrusive bodies of vario...The eastern part of the Caucasus orogen,termed the Georgian segment,is mainly underlain by highly deformed Lower-Middle Jurassic shales,sandstones,and volcaniclastic rocks,and cut by numerous intrusive bodies of various compositions.All units contain a variety of mineral deposit types and their surrounding zones of hydrothermal alteration.Detailed geological and metallogenic research,after 30 years stagnation,has led to important new information regarding the evolution of this region.Three main stages of magmatic activity are now clearly distinguished.The oldest magmatism comprises early Jurassic events,related to extensional tectonism,with volcanism and subvolcanic plutonism that ranged from rhyolitic,through dacitic and andesitic,and to basaltic.Additional extensional processes(in Bajocian times)were characterized by intrusion of a gabbro and diorite dike system into slightly older late Early Jurassicearly Middle Jurassic formations.The final magmatic event was associated with Middle Jurassic folding and uplift during which multiphase diorite plutons were emplaced.Intense hydrothermal activity related to this latest magmatism was responisble for important polymetallic mineralization including more than 100 historically recognized outcropping occurrences.A detailed study of 11of the more significant of these occurrences has indicated anomalous concentrations of base metals as well as gold,thorium,yttrium,cobalt,cadmium,and bismuth.In addition,several new and potentially significant mineral occurrences were discovered,including two designated here as Gelia and Lechuri.展开更多
The occurrences of associated elements and their genetic factors in the No. 30 coal seam in the Zhijin Coalfield were studied using instrumental neutron activation analysis, inductively coupled plasma-atomic emission ...The occurrences of associated elements and their genetic factors in the No. 30 coal seam in the Zhijin Coalfield were studied using instrumental neutron activation analysis, inductively coupled plasma-atomic emission spectroscopy, and a scanning electron microscope equipped with an energy-dispersive X-ray analyzer. And, a microscope photometer system (Leitz MPV-Ⅲ) was used to observe the characteristics of coal petrology. According to the influence degree by the siliceous low-temperature hydrothermal fluids, the organic matter is divided into four types: A, B, C, and D of the hydrothermally-altered organic matter (HAOM). The study shows that the high content of Fe (2.31%) is not from pyrite, but mostly from the siliceous low-temperature hydrothermal fluids. The occurrences of the associated elements in the four organic matter types are different. The contents of Fe, Si, and Al are decreasing, but S and Cu are increasing in the order of the HAOM-A, HAOM-B, HAOM-C, and HAOM-D. The losing rate of sulfur in organic matter is 0.35% and the content of Fe taken from the low-temperature hydrothermal fluids into the organic matter is 0.794% during the siliceous low-temperature hydrothermal fluids invading the coal seam. The above facts indicate that the low-temperature hydrothermal fluids play a crucial role in the re-distributions and occurrences of associated elements in coal.展开更多
The oil, gas and water volumes revealed by the productivity of exploratory wells do not reflect the actual underground situations. Under the geologic conditions, a certain amount of dissolved natural gas is stored in ...The oil, gas and water volumes revealed by the productivity of exploratory wells do not reflect the actual underground situations. Under the geologic conditions, a certain amount of dissolved natural gas is stored in oil or water. Based on the production test data of exploratory wells in the Tazhong uplift of the Tarim basin, this paper discusses in detail the differences in occurrence and distribution featrues between the surface and underground natural gases; presents a restoration of the surface gas occurrence to actual underground geologic conditions according to the dissolubility of natural gas under different temperature, pressure and medium conditions; and classifies the natural gas into three states, i.e. the oversaturated, saturated and undersaturated, according to its relative content underground. Through a comparative analysis of the differences in surface and underground occurrences of natural gas, it discusses the hydrocarbon reservoir formation mechanism and distribution rules, thereby providing guidances as new methods and technologies for the prediction of potential natural gas reservoir distribution in the study area.展开更多
The Bayan Obo deposit in northern China is an ultra-large Fe–REE–Nb deposit.The occurrences,and geochemical characteristics of thorium in iron ores from the Bayan Obo Main Ore Body were examined using chemical analy...The Bayan Obo deposit in northern China is an ultra-large Fe–REE–Nb deposit.The occurrences,and geochemical characteristics of thorium in iron ores from the Bayan Obo Main Ore Body were examined using chemical analysis,field emission scanning electron microscopy,energy dispersive spectrometer,and automatic mineral analysis software.Results identified that 91.69%of ThO2 in the combined samples was mainly distributed in rare earth minerals(bastnaesite,huanghoite,monazite;56.43%abundance in the samples),iron minerals(magnetite,hematite,pyrite;20.97%),niobium minerals(aeschynite;14.29%),and gangue minerals(aegirine,riebeckite,mica,dolomite,apatite,fluorite;4.22%).An unidentified portion(4.09%)of ThO2 may occur in other niobium minerals(niobite,ilmenorutile,pyrochlore).Only a few independent minerals of thorium occur in the iron ore samples.Thorium mainly occurs in rare earth minerals in the form of isomorphic substitution.Analyses of the geochemical characteristics of the major elements indicate that thorium mineralization in the Main Ore Body was related to alkali metasomatism,which provided source material and favorable porosity for hydrothermal mineralization.Trace elements such as Sc,Nb,Zr,and Ta have higher correlation coefficients with thorium,which resulted from being related to the relevant minerals formed during thorium mineralization.In addition,correlation analysis of ThO2 and TFe,and REO and TFe in the six types of iron ore samples showed that ThO2 did not always account for the highest distribution rate in rare earth minerals,and the main occurrence minerals of ThO2 were closely related to iron ore types.展开更多
A systematic study of occurrences of silver in 156 Pb-Zn-Cu ore deposits indicates that silver mainly occurs in nonferrous metal ore deposits in forms of association and paragenesis. It occurs mainly as independent mi...A systematic study of occurrences of silver in 156 Pb-Zn-Cu ore deposits indicates that silver mainly occurs in nonferrous metal ore deposits in forms of association and paragenesis. It occurs mainly as independent minerals in nature and occasionally as ion adsorption, isomorphous or amorphous silver minerals. Nearly 190 silver minerals have been discovered in China. Their shapes, constituents, textures, grain sizes, embedded types, distribution patterns, mineral assemblages and metallogenic series suggest that these characteristics are closely related to geneses of deposits and dependent of ore-forming conditions. Pb, Zn and Cu sulphides are the main carrier minerals of silver. The partition of silver in ore is constrained by the mineralization intensity, grain size and embedded form of silver minerals and mineral assemblages.展开更多
The temporal and spatial distributions of all the 259 M≥6 earthquakes of eastern Chinese mainland (λ≥108° E) and its adjacent area and all the 153 M≥7 earthquakes of western Chinese mainland (λ<108°E...The temporal and spatial distributions of all the 259 M≥6 earthquakes of eastern Chinese mainland (λ≥108° E) and its adjacent area and all the 153 M≥7 earthquakes of western Chinese mainland (λ<108°E) and its adjacent area up to 1991 were analyzed systematically.These earthquakes are called as strong earthquakes and those of the east before and after 1600,and those of the west before and after 1900, are called respectively as former ones and latter ones.Most of these events were divided into 45 sets of which the each relatively concentrated in both time and space and took the form of group.In the grouping form,the probability of occurrence of a strong earthquake higher than the average appeared simultaneously in time and space.The grouping occurrences of the strong earthquakes of Chinese mainland has been determined as a fundamental feature of the seismicity.展开更多
This study examined the impact of climate change on the occurrence of malaria,pneumonia,meningitis,and cholera in Lokoja City,Nigeria,with the aim of investigating the spatial distribution and prevalence of the four k...This study examined the impact of climate change on the occurrence of malaria,pneumonia,meningitis,and cholera in Lokoja City,Nigeria,with the aim of investigating the spatial distribution and prevalence of the four kinds of diseases as well as the coping strategies of people in the area.We collected the rainfall and temperature data of Lokoja City during 2000-2020 from the National Aeronautics and Space Administration(NASA),and the medical records data of the four kinds of diseases from the Kogi State Ministry of Health.We also conducted a semi-structured questionnaire of 250 residents,who have experienced one of these diseases,to investigate their coping strategies with these diseases.The Pearson correlation and multiple regression analysis were used to research the relationship between the climate parameters and cases of diseases.The result showed annual variations in climatic parameters with R^(2)values of 0.0557,0.0009,and 0.4915 for rainfall,maximum temperature,and minimum temperature,respectively.A positive and significant relationship were observed between maximum temperature and malaria(r=0.80),rainfall and malaria(r=0.54),minimum temperature and meningitis(r=0.64),as well as rainfall and cholera(r=0.66)at P<0.05 level.For the regression analysis R^(2)=0.71,0.50,and 0.52 for malaria,cholera,and meningitis,respectively at P<0.05 level.During 2000-2020,cases of malaria were highest in Ward A with 15,422,while 715 cases of pneumonia were highest in Kupa North Ward.In Ward A,3787 cases of cholera were recorded to be the highest,while cases of meningitis were highest in Kupa North Ward with 2383 cases.Investigation revealed that malaria is more common in the wet season,while cholera and meningitis cases were highest in the dry season.The study revealed that the most practiced coping strategy is the use of medications by about 90%of the respondents.More studies are recommended in the study area to establish a causal link between climate change and disease occurrence,and intervention from government in form of prevention and control programmes should be vigorously implemented.展开更多
Background Cotton crop is infested by numerous arthropod pests from sowing to harvesting,causing substantial direct and indirect yield losses.Knowledge of seasonal population trends and the relative occurrence of pest...Background Cotton crop is infested by numerous arthropod pests from sowing to harvesting,causing substantial direct and indirect yield losses.Knowledge of seasonal population trends and the relative occurrence of pests and their natural enemies is required to minimize the pest population and yield losses.In the current study,analysis of the seasonal population trend of pests and natural enemies and their relative occurrence on cultivars of three cotton species in Central India has been carried out.Results A higher number and diversity of sucking pests were observed during the vegetative cotton growth stage(60 days after sowing),declining as the crop matured.With the exception of cotton jassid(Amrasca biguttula biguttula Ishida),which caused significant crop damage mainly from August to September;populations of other sucking insects seldom reached economic threshold levels(ETL)throughout the studied period.The bollworm complex populations were minimal,except for the pink bollworm(Pectinophora gossypiella Saunders),which re-emerged as a menace to cotton crops during the cotton cropping season 2017–2018 due to resistance development against Bt-cotton.A reasonably good number of predatory arthropods,including coccinellids,lacewings,and spiders,were found actively preying on the arthropod pest complex of the cotton crop during the early vegetative growth stage.Linear regression indicates a significant relationship between green boll infestations and pink bollworm moths in pheromone traps.Multiple linear regression analyse showed mean weekly weather at one-or two-week lag periods had a significant impact on sucking pest population(cotton aphid,cotton jassid,cotton whitefly,and onion thrips)fluctuation.Gossypium hirsutum cultivars RCH 2 and DCH 32,and G.barbadense cultivar Suvin were found susceptible to cotton jassid and onion thrips.Phule Dhanvantary,an G.arboreum cotton cultivar,demonstrated the highest tolerance among all evaluated cultivars against all sucking pests.Conclusion These findings have important implications for pest management in cotton crops.Susceptible cultivars warrant more attention for plant protection measures,making them more input-intensive.The choice of appropriate cultivars can help minimize input costs,thereby increasing net returns for cotton farmers.展开更多
Alkaline lacustrine shale is highly heterogeneous,and the complex relationship between the organicinorganic porosity network and hydrocarbon occurrence restricts the effectiveness of shale oil exploration and developm...Alkaline lacustrine shale is highly heterogeneous,and the complex relationship between the organicinorganic porosity network and hydrocarbon occurrence restricts the effectiveness of shale oil exploration and development.Herein,we investigated the Fengcheng Formation(P_(1)f)in Mahu Sag.This study integrated geochemistry,Soxhlet extraction,scanning electron microscopy,gas adsorption,and nuclear magnetic resonance T_(1)-T_(2)spectroscopy to elucidate the microscopic oil occurrence mechanisms in shales.Results indicate the presence of felsic shale,dolomitic shale,lime shale,and mixed shale within the P_(1)f.Matrix pores and microfractures associated with inorganic minerals are the predominant pore types in P_(1)f.Adsorbed oil primarily resides on the surfaces of organic matter and clay minerals,while free oil predominantly occupies inorganic pores and microfractures with larger pore sizes.Variations exist in the quantity and distribution of shale oil accumulation across different scales,where free oil and adsorbed oil are governed by dominant pores with diameters exceeding 10 nm and ineffective pores with diameters below 10 nm,respectively.Shale oil occurrence characteristics are influenced by organic matter,pore structure,and mineral composition.Felsic shale exhibits a high abundance of dominant pores,possesses the highest oil content,predominantly harbors free oil within these dominant pores,and demonstrates good mobility.Fluid occurrence in dolomitic shale and lime shale is intricate,with low oil content and a free oil to adsorbed oil ratio of 1:1.Mixed shale exhibits elevated clay mineral content and a scarcity of dominant pores.Moreover,ineffective pores contain increased bound water,resulting in medium oil content and limited mobility predominantly due to adsorption.Presently,shale oil mainly occurs in the dominant pores with a diameter larger than 10 nm in a free state.During the exploration and development of alkaline lacustrine shale oil resources,emphasis should be placed on identifying sweet spots within the felsic shale characterized by dominant pores.展开更多
As coal mining depth increases,the combined effects of high stress,mining stress,and fault structures make dynamic impact hazards more frequent.The reproduction of dynamic impact phenomena is basis for studying their ...As coal mining depth increases,the combined effects of high stress,mining stress,and fault structures make dynamic impact hazards more frequent.The reproduction of dynamic impact phenomena is basis for studying their occurrence patterns and control mechanisms.Physical simulation test represents an efficacious methodology.However,there is currently a lack of simulation devices that can effectively simulate two types of dynamic impact phenomena,including high stress and fault slip dynamic impact.To solve aforementioned issues,the physical simulation test system for dynamic impact in deep roadways developed by authors is employed to carry out comparative tests of high stress and fault slip dynamic impact.The phenomena of high stress and fault slip dynamic impact are reproduced successfully.A comparative analysis is conducted on dynamic phenomena,stress evolution,roadway deformation,and support force.The high stress dynamic impact roadway instability mode,which is characterized by the release of high energy accompanied by symmetric damage,and the fault slip dynamic impact roadway instability mode,which is characterized by the propagation of unilateral stress waves accompanied by asymmetric damage,are clarified.On the basis,the differentiated control concepts for different types of dynamic impact in deep roadways are proposed.展开更多
The global energy demand is increasing rapidly,and it is imperative to develop shale hydrocarbon re-sources vigorously.The prerequisite for enhancing the exploitation efficiency of shale reservoirs is the systematic e...The global energy demand is increasing rapidly,and it is imperative to develop shale hydrocarbon re-sources vigorously.The prerequisite for enhancing the exploitation efficiency of shale reservoirs is the systematic elucidation of the occurrence characteristics,flow behavior,and enhanced oil recovery(EOR)mechanisms of shale oil within commonly developed nanopores.Molecular dynamics(MD)technique can simulate the occurrence,flow,and extraction processes of shale oil at the nanoscale,and then quantitatively characterize various fluid properties,flow characteristics,and action mechanisms under different reservoir conditions by calculating and analyzing a series of MD parameters.However,the existing review on the application of MD simulation in shale oil reservoirs is not systematic enough and lacks a summary of technical challenges and solutions.Therefore,recent MD studies on shale oil res-ervoirs were summarized and analyzed.Firstly,the applicability of force fields and ensembles of MD in shale reservoirs with different reservoir conditions and fluid properties was discussed.Subsequently,the calculation methods and application examples of MD parameters characterizing various properties of fluids at the microscale were summarized.Then,the application of MD simulation in the study of shale oil occurrence characteristics,flow behavior,and EOR mechanisms was reviewed,along with the elucidation of corresponding micro-mechanisms.Moreover,influencing factors of pore structure,wall properties,reservoir conditions,fluid components,injection/production parameters,formation water,and inorganic salt ions were analyzed,and some new conclusions were obtained.Finally,the main challenges associated with the application of MD simulations to shale oil reservoirs were discussed,and reasonable prospects for future MD research directions were proposed.The purpose of this review is to provide theoretical basis and methodological support for applying MD simulation to study shale oil reservoirs.展开更多
The prevalence of Solenopsis invicta is associated with habitat diversity,with a preference for various habitats ranked in the following order:ponds,wastelands,green belts,roads,parks,farmlands,and villages.Consequent...The prevalence of Solenopsis invicta is associated with habitat diversity,with a preference for various habitats ranked in the following order:ponds,wastelands,green belts,roads,parks,farmlands,and villages.Consequently,management strategies should be tailored to each habitat.There are two occurrence peaks of S.invicta throughout the year,specifically from March to April and from September to October.It is essential to emphasize prevention and control measures during the active periods of S.invicta.To enhance the effectiveness of these measures,supplementary control should be implemented within 10-15 d following the initial prevention and control efforts.Furthermore,the efficacy of prevention and control is notably higher on the second to third day immediately following rainfall.This study aimed to evaluate the efficacy of various agents in controlling S.invicta.A comparative analysis was conducted on the efficacy of three different brands of agents against S.invicta.The findings indicated that a concentration of 0.08%-0.10%indoxacarb exhibited a comparable extermination effect on S.invicta worker ants.However,agents with larger particle sizes demonstrated a reduced efficacy in exterminating S.invicta nests.展开更多
To explore the geochemical characteristics and genesis of the elements in ferromanganese nodules from the Northwest Pacific,this study analyses the mineral composition,elemental content,occurrence phase and genetic me...To explore the geochemical characteristics and genesis of the elements in ferromanganese nodules from the Northwest Pacific,this study analyses the mineral composition,elemental content,occurrence phase and genetic mechanisms of samples by X-ray diffraction(XRD),inductively coupled plasma-optical emission spectrometry(ICP-OES),inductively coupled plasma-mass spectrometry(ICP-MS)and phase analysis methods.The results show that ferromanganese nodules are mainly hydrogenetic,and Mn/Fe content ratio ranges from 0.95 to 2.05.The major minerals are vernadite(δ-MnO_(2))and amorphous ferric oxyhydroxide(FeOOH),and the secondary minerals include todorokite,birnessite,quartz and plagioclase.Ferromanganese nodules contain high contents of Co(0.24%-0.42%),Cu(0.23%-0.73%),Ni(0.33%-0.86%)and rare earth elements(REEs,1192-1990μg/g),which have positive Ce and negative Y anomalies but no Eu anomaly.A cluster analysis suggests that the elements in ferromanganese nodules can be divided into three groups:hydrogenetic components,including Fe,Ti,Zr,P,Pb,Co,Ba,Sr,V and REEs;diagenetic components,including Mn,Ni,Mg,Zn and Cu;and detrital components,including Al,Na,K and Ca.According to chemical leaching,ferromanganese nodules can be divided into four phases:Na,Ca,Mg and Sr are mainly enriched in the carbonate phase;Mn,Co,Ni and Ba are mainly enriched in the Mn-oxide phase;Fe,P,Ti,Cu,Pb,V,Zn,Zr and REEs are mainly enriched in the Fe-oxide phase;and Al and K are mainly enriched in the residual phase.A combination of the two different methods reveal selective enrichment of metal elements from seawater by ferromanganese nodules,featuring multisource mineralization.Moreover,through ion exchange and adsorption,approximately 71.2%of REEs are enriched in the Fe-oxide phase,15.4%in the Mn-oxide phase and 12.4%in the residual phase,while REE contents in the carbonate phase are relatively low.In addition,under the oxic conditions of seawater,the oxidation of soluble Ce^(3+)to insoluble CeO_(2)together with Fe-Mn minerals results in Ce enrichment in ferromanganese nodules.This study provides a reference for the metallogenesis of ferromanganese nodules from the Northwest Pacific.展开更多
The annual average number of snowstorm days in Tongliao area is 1-3 d.Snowstorms mainly happen from October to next May,peaking from December to next March.The incidence is the highest between 12:00 and 15:00.The Mong...The annual average number of snowstorm days in Tongliao area is 1-3 d.Snowstorms mainly happen from October to next May,peaking from December to next March.The incidence is the highest between 12:00 and 15:00.The Mongolian low vortex is the main weather system that triggers snowstorms,and can be classified into three types:small trough development,horizontal trough becoming vertical,and low trough moving eastwards.Snowstorms pose a relatively serious threat to agricultural and animal husbandry production,transportation,power and communication in Tongliao.Especially in spring,snowstorm weather poses a greater threat to agriculture and animal husbandry in Tongliao.It is needed to pay attention to the impact of extreme weather and climate events such as snowstorms,strengthen research on the mechanisms of disaster-causing weather,enhance the early warning capability of disasters,and provide good service guarantees for low-temperature weather in winter.展开更多
BACKGROUND The intestinal flora(IF)has been linked to risks of non-communicable diseases,especially various cancers,stroke,and Alzheimer’s disease.However,many uncertainties of these associations during different sta...BACKGROUND The intestinal flora(IF)has been linked to risks of non-communicable diseases,especially various cancers,stroke,and Alzheimer’s disease.However,many uncertainties of these associations during different stages of growth,deve-lopment,and aging still exist.Therefore,further in-depth explorations are warranted.AIM To explore the associations of the human IF with disease risks during different stages of growth,development,and aging to achieve more accurate and con-vincing conclusions.METHODS Cohort,cross-sectional,case-control,and Mendelian randomization studies published in the PubMed and Web of Science databases until December 31,2023 were systematically reviewed to clarify the associations of the IF at the genus level with the risks of various non-communicable diseases,which were grouped in accordance with the 10^(th) revision of the International Classification of Diseases.RESULTS In total,57 studies were included to quantitatively examine the influence of the IF on the risks of 30 non-communicable diseases during different stages of growth,development,and aging.Population studies and Mendelian randomization studies confirmed positive associations of the abundances of Bifidobacterium and Ruminococcus with multiple sclerosis.CONCLUSION These findings contribute to a deeper understanding of the roles of the IF and provide novel evidence for effective strategies for the prevention and treatment of non-communicable diseases.In the future,it will be necessary to explore a greater variety of research techniques to uncover the specific mechanisms by which gut microbiota trigger diseases and conduct in-depth studies on the temporal relationship between microbiota alterations and diseases,so as to clarify the causal relationship more accurately.展开更多
The number of newborns born with diseases is increasing recently.Thyroid hormones(THs)are closely related to the growth and development of the newborn in the mother's womb and to the carriage of related diseases a...The number of newborns born with diseases is increasing recently.Thyroid hormones(THs)are closely related to the growth and development of the newborn in the mother's womb and to the carriage of related diseases after birth.Environmental endocrine-disrupting compounds(EDCs)have been proven to harm THs in newborns.Phthalates(PAEs),a typical class of EDCs,are commonly used in toys,childcare materials,and food contact materials,which have been closely connected with neonatal thyroid dysfunction and thyroid-related diseases.As restrictions on PAEs becomemore stringent in neonatal field,numerous PAE alternatives are emerging.Associations between exposure to PAEs and their alternatives and dysfunctions in THs have been explored.Hence,we summarized the body burdens and regional characteristics of PAEs and their alternatives in neonatal urine,cord blood,and meconium.Subsequently,the influences of PAEs and their alternatives on thyroid dysfunction,prematurity,low birth weight,fetal growth restriction,respiratory dysfunction,immune disorders,neurological disorders,and reproductive disorders in newborns were evaluated.Furthermore,we scrutinized the effects of PAEs and their alternatives on the neonatal thyroid from signaling,substance transport,and hormone production to explore the underlying mechanisms of action on neonatal thyroid and thyroid-related disorders.As the declining global trends of healthy newborns and the potential impacts of PAEs and their alternatives on thyroid function,a more comprehensive study is needed to discuss their effects on newborns and their underlying mechanisms.This review facilitates attention to the effects of PAEs and their alternatives on thyroid and thyroid-related disorders in newborns.展开更多
文摘This article addresses where ruts are likely to occur during in-field forest operations. This was done by inspecting high-resolution surface images across New Brunswick (NB) and elsewhere to mark where ruts have (1) and have not (0) occurred in harvested cutblocks. This marking revealed 1) where off-road operations were likely done on moist to wet and unfrozen soils;and 2) whether the ruts so incurred were water-logged at the time of imaging. Through geospatial processing of the NB-wide digital elevation model (DEM, available at 1 m resolution), the following attributes were added to each of the marked rut and no-rut locations: 1) the cartographic depth-to-water (DTW) as referenced to the nearest flow channels with >1 and >4 ha upslope flow accumulation areas (FA);2) the topographic position index (TPI) in reference to the mean annulus elevation 50 m away from each DEM cell;3) mean slope and curvatures within each cell-surrounding 10-m circle;4) the terrain wetness index (TWI);5) soil association type according to the NB forest soil map, adjusted for NB’s most recent hydrographic network delineations for waterbodies and wetlands. Subjecting these data to logistic regression analysis revealed that image-located off-road rutting occurred at about 90% probability in water-accumulating zones where TPI is <0 m and DTW is <1 m. Using slope, curvature, TWI, and soil type as additional rut occurrence predictors did not affect this zonation significantly.
基金supported by the National Natural Science Foundation of China(Grant No.41402126)
文摘ObjectiveThis study aims to characterize the occurrences and interior structural features of botryoidal structures from the Sinian Dengying Formation in the Sichuan Basin of Southwestern China, and to shed light on their formation mechanism.
基金the project IGCP-649 and was supported by RFBR (grant 17-05-00097)the Ural Branch of RAS (project 15-18-5-24)
文摘It is known that the formation of oceanic crust occurs in different geodynamic settings,accompanying by the emergence of mantle-magmatic ophiolite complexes having a distinctive properties.In the process of mantle-crustal evolution of the ophiolites are undergoing significant changes with the formation of peculiar(on structure and composition)rocks,sometimes with unusual mineral paragenesis.The presence of such rocks in mélange tectonic zones greatly complicates to determine their origin.In the Ural folded belt(length more than 2,000 km)separating the East European Platform and the West Siberian sedimentary basin,ophiolites are widespread forming a chain of mafic-ultramafic massifs(Fig.1)located in the allochthonous position with mélange at the bottom(Puchkov,2013).With the Urals ophiolites are associated occurrences of eclogites,jadeites,ruby and other rocks of unclear nature,sometimes regarded as potentially diamondiferous.Such formations of unclear genesis include the associating with ophiolites metabasites of higher alkalinity composing the body in the mantle peridotites of the mélange Main Uralian Fault(MUF)zone(Shmelev,2005).By this time they are determined in different parts of the fault zone,but most completely are known in the Sub Polar Urals,where are distinguished under the name of Sertynya alkaline-ultramafic complex,which is located just 25 km east of Hartes kimberlitic complex(Fig.1).Formally,its affiliation to diamond-bearing associations is confirmed by finding of grains and fragments of natural diamond in the weathering crust.A detailed study of the rock complexes shows that in reality they have a polygenic nature,combine theelements of proper magmatic and fluidizate-explosive formations,the appearance of which was interfaced with the processes at the slab-mantle wedge boundary in subduction zones.Polygenic nature of the rocks is reflected in the existence of three interrelated structural-geological units:(1)bodies and dikes of uniformmetadiabasesanddensefine-grainedmetadolerites(lamprophyres),(2)fluidal-brecciated dolerites('tuff breccias')and(3)structural weathering crust with angular or rounded fragments(blocks)of metadolerites and serpentinites.The rocks have experienced rodingitization and permeated with net of veins a vesuvianite composition.The host peridotite matrix(harzburgites and dunites)has undergone serpentinizationandchloritization.Structural relationships give grounds for distinguishing in the history of the complex formation the magmatic proper(dolerite dyke and lamprophyre intrusion)and infiltration fluidizate-explosive(metasomatic transformation of dolerite)stages.Peculiarities of petrography and mineralogy of rock complexes does not allow to compare them with lamproites and kimberlites.Metadiabases demonstrate relics of ophitic structure,as primary paragenesis is completely replaced by aggregate of chlorite,zoisite and leucoxene.Dolerites(lamprophyres)have a uniform fine-grained or porphyry structure with phenocrysts of clinopyroxene,brown amphibole and leucoxene(sphene),which are immersed in a fine-scaly aggregate of light green mica.In the rocks amphibole,garnet and vesuvian are present.Clinopyroxene corresponds to augite with moderate content of titanium and alumina(up to 3.5wt.%),showing a normal magmatic zonation in composition.Mica previously wrongly called as phlogopite,actually has an extremely ferrous composition and corresponds to biotite(annite).Amphibole is presented by magmatic titaniferous tschermakite hornblende and metamorphic(bluish)variety of sodium-calcium composition(taramite).Garnet is presented by exceptionally grossular of rodingite type.Mineralogy of weathering crust reveals similar features,but in the samples it is marked the presence of muscovite,orthoclase and weakly ferrous diopside.An important feature of the weathering crust is the presence of shear surfaces on minerals,resulting in fracturing due to internal stress,confirming the explosive nature of protolith.The bulk chemical composition of rocks is characterized by significant variations in the content of silica(30-46 wt.%)and alkalis(0-6.5 wt.%).These metabasites have consistently a low magnesia number and high titanium oxide content(1.5-3.0 wt.%).Side by side with these are been established the uniform slope REE distribution trends similar to the trend of oceanic basalts N-MORB type(Fig.2).The level of trace element compositions does not depend on variations in the alkalinity of the rocks,but clearly correlates with the titanium content.Unlike them the Hartes kimberlites demonstrate the distribution with deficit of HREE,andthe level of the elements content is correlated with the alkalinity of rocks(Mahotkin et al.,1998).Another important geochemical feature of the Sertynya complex rocks is a regular behavior of the mobile LILE elements(Cs,Rb,Ba,K).In the varieties of rocks with mica enriched by alkalis,it is recorded extremely high level of LILE,exceeding the level of contents in N-MORB basalts at 10-10000 times!In the metabasites varieties with low level of alkalinity,LILE content is sharply(except Cs)reduced to minimum values(Fig.2).The observed pattern of the element distribution is undoubtedly the result of postmagmatic fluid-metasomatic alteration of the original rocks.Tectonic position and the primary composition characteristics of the metadolerites give reason to consider them as fragments of the ophiolite sheeted dike complex(Shmelev,2005).The famous dike complexes in the ophiolite massifs of the MUF zone(east of mélange)belong to suprasubduction formations of Paleozoic age.However the obtained mainly ancient U-Pb zircon dating(up to Archean inclusive)for metadolerites of the Sertynya complex,make it possible to assume its Vendian-Early Cambrian(530-617 Ma)age.It permits to compare the Sertynya metabasites with the Vendian metaophiolites of the MUF zone in the Middle Urals(Petrov et al.,2010).It is noteworthy that similar age datings(520-550 Ma)are also established for kimberlites of the Hartes complex located to the west of ophiolites.Therefore,thepresenceofthe Vendian-Cambrian ophiolite of MOR-type in the MUF mélange zone,'changing'to the east of Ordovician ophiolites SSZ-type,seems quite possible.The obtained data allow to suggest an original interpretation of nature of the Urals fluidizate-explosive formations considering the process specifics in the subduction zones(Bebout and Barton,2002).Accordingto this model,the pre-Ordovician(?)oceanic crust has undergone transformations and deformations on the slab-mantle wedge boundary during the subduction.As a result of slab dehydration it occurred a flow of aqueous fluids,which were enriched with the extracted from sedimentary rocks the LILE elements and percolated through the mantle substrate with dolerite dyke complex.Interaction with them led to the formation of chlorite-zoisite and/or mica(biotite-bearing)fluidizates and in the presence of a gas phase-fluidizate-explosive breccias with subsequent development of weathering crust.In the surrounding peridotites an explosive process is marked by the formation of pseudokimberlite breccias.Fluidized-explosive occurrences in mantle peridotites of mélange zones should be considered as indicators of the subduction slab-mantle interaction at relatively shallow levels involving enriched LILE fluids(without melts participation),rising as the front from the subduction zone.In this interpretation,there is no need toappealtothealkaline-ultramaficor lamproit-kimberlite hypothesis of the genesis of these formations,however,the question of their potential diamondiferous remains to be open.The proposed interpretation of the fluidizate-explosive occurrences makes it possible to comprehendthat in reality the mélange is a complex formation with signs of not onlycollisional(as usually is considered),but also of earlier subduction events.
基金the Rustaveli National Science Foundation of Georgia for funding the project(#GNSF/ST09-1071-5-150).
文摘Kakheti and Tusheti regions(Eastern Graeter Caucasus),of the Georgia Republic are mainly underlain by highly deformed Lower-Middle Jurassic shales,sandstones,and volcaniclastic rocks,intruded by numerous intrusive bodies of various compositions.All units contain a variety of ore mineral deposit types and their surrounding zones of hydrothermal alteration.Continued geological and metallogenic researches in the past 30 years have led to important new information regarding the evolution of this region.Three main stages of magmatic activity are now clearly distinguished.Oldest magmatism comprises Early Jurassic events,related to extensional tectonism,which ranged from rhyolitic,through dacitic and andesitic,and to basaltic magma.Additional extensional processes(in Bajocian)were characterized by intrusion of a gabbro and diorite dike system into recently deposited late Early Jurassic-early Middle Jurassic formations.The final magmatic event was associated with Middle Jurassic folding and uplift during which multiphase diorite plutons were emplaced.Related intense hydrothermal activity was responsible for important polymetallic mineralization,with more than 100 recognized outcropping ore occurrences.A detailed study of 11 of these ore occurrences has indicated anomalous concentrations of gold,thorium,yttrium,cobalt,cadmium,and bismuth.In addition,several new and potentially significant ore mineral occurrences were discovered.
基金Rustaveli National Science Foundation of Georgia for funding the project(#GNSF/ST09-1071-5-150)through which the research work was conducted in the eastern Greater Caucasus.
文摘The eastern part of the Caucasus orogen,termed the Georgian segment,is mainly underlain by highly deformed Lower-Middle Jurassic shales,sandstones,and volcaniclastic rocks,and cut by numerous intrusive bodies of various compositions.All units contain a variety of mineral deposit types and their surrounding zones of hydrothermal alteration.Detailed geological and metallogenic research,after 30 years stagnation,has led to important new information regarding the evolution of this region.Three main stages of magmatic activity are now clearly distinguished.The oldest magmatism comprises early Jurassic events,related to extensional tectonism,with volcanism and subvolcanic plutonism that ranged from rhyolitic,through dacitic and andesitic,and to basaltic.Additional extensional processes(in Bajocian times)were characterized by intrusion of a gabbro and diorite dike system into slightly older late Early Jurassicearly Middle Jurassic formations.The final magmatic event was associated with Middle Jurassic folding and uplift during which multiphase diorite plutons were emplaced.Intense hydrothermal activity related to this latest magmatism was responisble for important polymetallic mineralization including more than 100 historically recognized outcropping occurrences.A detailed study of 11of the more significant of these occurrences has indicated anomalous concentrations of base metals as well as gold,thorium,yttrium,cobalt,cadmium,and bismuth.In addition,several new and potentially significant mineral occurrences were discovered,including two designated here as Gelia and Lechuri.
基金the National NaturalScience Foundation of China(No.40072054)the Coal Science Foundation of China(No.97Geo-10205).
文摘The occurrences of associated elements and their genetic factors in the No. 30 coal seam in the Zhijin Coalfield were studied using instrumental neutron activation analysis, inductively coupled plasma-atomic emission spectroscopy, and a scanning electron microscope equipped with an energy-dispersive X-ray analyzer. And, a microscope photometer system (Leitz MPV-Ⅲ) was used to observe the characteristics of coal petrology. According to the influence degree by the siliceous low-temperature hydrothermal fluids, the organic matter is divided into four types: A, B, C, and D of the hydrothermally-altered organic matter (HAOM). The study shows that the high content of Fe (2.31%) is not from pyrite, but mostly from the siliceous low-temperature hydrothermal fluids. The occurrences of the associated elements in the four organic matter types are different. The contents of Fe, Si, and Al are decreasing, but S and Cu are increasing in the order of the HAOM-A, HAOM-B, HAOM-C, and HAOM-D. The losing rate of sulfur in organic matter is 0.35% and the content of Fe taken from the low-temperature hydrothermal fluids into the organic matter is 0.794% during the siliceous low-temperature hydrothermal fluids invading the coal seam. The above facts indicate that the low-temperature hydrothermal fluids play a crucial role in the re-distributions and occurrences of associated elements in coal.
基金supported by the State Key Basic Research Program 973(No.2006CB202308)
文摘The oil, gas and water volumes revealed by the productivity of exploratory wells do not reflect the actual underground situations. Under the geologic conditions, a certain amount of dissolved natural gas is stored in oil or water. Based on the production test data of exploratory wells in the Tazhong uplift of the Tarim basin, this paper discusses in detail the differences in occurrence and distribution featrues between the surface and underground natural gases; presents a restoration of the surface gas occurrence to actual underground geologic conditions according to the dissolubility of natural gas under different temperature, pressure and medium conditions; and classifies the natural gas into three states, i.e. the oversaturated, saturated and undersaturated, according to its relative content underground. Through a comparative analysis of the differences in surface and underground occurrences of natural gas, it discusses the hydrocarbon reservoir formation mechanism and distribution rules, thereby providing guidances as new methods and technologies for the prediction of potential natural gas reservoir distribution in the study area.
基金supported by the National Basic Research Program of China (973 Program) (2012CBA01200)Northern Rare Earth Science and Technology Project (BFXT-2015D-0002) and (2016H1928)
文摘The Bayan Obo deposit in northern China is an ultra-large Fe–REE–Nb deposit.The occurrences,and geochemical characteristics of thorium in iron ores from the Bayan Obo Main Ore Body were examined using chemical analysis,field emission scanning electron microscopy,energy dispersive spectrometer,and automatic mineral analysis software.Results identified that 91.69%of ThO2 in the combined samples was mainly distributed in rare earth minerals(bastnaesite,huanghoite,monazite;56.43%abundance in the samples),iron minerals(magnetite,hematite,pyrite;20.97%),niobium minerals(aeschynite;14.29%),and gangue minerals(aegirine,riebeckite,mica,dolomite,apatite,fluorite;4.22%).An unidentified portion(4.09%)of ThO2 may occur in other niobium minerals(niobite,ilmenorutile,pyrochlore).Only a few independent minerals of thorium occur in the iron ore samples.Thorium mainly occurs in rare earth minerals in the form of isomorphic substitution.Analyses of the geochemical characteristics of the major elements indicate that thorium mineralization in the Main Ore Body was related to alkali metasomatism,which provided source material and favorable porosity for hydrothermal mineralization.Trace elements such as Sc,Nb,Zr,and Ta have higher correlation coefficients with thorium,which resulted from being related to the relevant minerals formed during thorium mineralization.In addition,correlation analysis of ThO2 and TFe,and REO and TFe in the six types of iron ore samples showed that ThO2 did not always account for the highest distribution rate in rare earth minerals,and the main occurrence minerals of ThO2 were closely related to iron ore types.
文摘A systematic study of occurrences of silver in 156 Pb-Zn-Cu ore deposits indicates that silver mainly occurs in nonferrous metal ore deposits in forms of association and paragenesis. It occurs mainly as independent minerals in nature and occasionally as ion adsorption, isomorphous or amorphous silver minerals. Nearly 190 silver minerals have been discovered in China. Their shapes, constituents, textures, grain sizes, embedded types, distribution patterns, mineral assemblages and metallogenic series suggest that these characteristics are closely related to geneses of deposits and dependent of ore-forming conditions. Pb, Zn and Cu sulphides are the main carrier minerals of silver. The partition of silver in ore is constrained by the mineralization intensity, grain size and embedded form of silver minerals and mineral assemblages.
文摘The temporal and spatial distributions of all the 259 M≥6 earthquakes of eastern Chinese mainland (λ≥108° E) and its adjacent area and all the 153 M≥7 earthquakes of western Chinese mainland (λ<108°E) and its adjacent area up to 1991 were analyzed systematically.These earthquakes are called as strong earthquakes and those of the east before and after 1600,and those of the west before and after 1900, are called respectively as former ones and latter ones.Most of these events were divided into 45 sets of which the each relatively concentrated in both time and space and took the form of group.In the grouping form,the probability of occurrence of a strong earthquake higher than the average appeared simultaneously in time and space.The grouping occurrences of the strong earthquakes of Chinese mainland has been determined as a fundamental feature of the seismicity.
文摘This study examined the impact of climate change on the occurrence of malaria,pneumonia,meningitis,and cholera in Lokoja City,Nigeria,with the aim of investigating the spatial distribution and prevalence of the four kinds of diseases as well as the coping strategies of people in the area.We collected the rainfall and temperature data of Lokoja City during 2000-2020 from the National Aeronautics and Space Administration(NASA),and the medical records data of the four kinds of diseases from the Kogi State Ministry of Health.We also conducted a semi-structured questionnaire of 250 residents,who have experienced one of these diseases,to investigate their coping strategies with these diseases.The Pearson correlation and multiple regression analysis were used to research the relationship between the climate parameters and cases of diseases.The result showed annual variations in climatic parameters with R^(2)values of 0.0557,0.0009,and 0.4915 for rainfall,maximum temperature,and minimum temperature,respectively.A positive and significant relationship were observed between maximum temperature and malaria(r=0.80),rainfall and malaria(r=0.54),minimum temperature and meningitis(r=0.64),as well as rainfall and cholera(r=0.66)at P<0.05 level.For the regression analysis R^(2)=0.71,0.50,and 0.52 for malaria,cholera,and meningitis,respectively at P<0.05 level.During 2000-2020,cases of malaria were highest in Ward A with 15,422,while 715 cases of pneumonia were highest in Kupa North Ward.In Ward A,3787 cases of cholera were recorded to be the highest,while cases of meningitis were highest in Kupa North Ward with 2383 cases.Investigation revealed that malaria is more common in the wet season,while cholera and meningitis cases were highest in the dry season.The study revealed that the most practiced coping strategy is the use of medications by about 90%of the respondents.More studies are recommended in the study area to establish a causal link between climate change and disease occurrence,and intervention from government in form of prevention and control programmes should be vigorously implemented.
基金Funding support for the Crop Pest Surveillance and Advisory Project(CROPSAP)。
文摘Background Cotton crop is infested by numerous arthropod pests from sowing to harvesting,causing substantial direct and indirect yield losses.Knowledge of seasonal population trends and the relative occurrence of pests and their natural enemies is required to minimize the pest population and yield losses.In the current study,analysis of the seasonal population trend of pests and natural enemies and their relative occurrence on cultivars of three cotton species in Central India has been carried out.Results A higher number and diversity of sucking pests were observed during the vegetative cotton growth stage(60 days after sowing),declining as the crop matured.With the exception of cotton jassid(Amrasca biguttula biguttula Ishida),which caused significant crop damage mainly from August to September;populations of other sucking insects seldom reached economic threshold levels(ETL)throughout the studied period.The bollworm complex populations were minimal,except for the pink bollworm(Pectinophora gossypiella Saunders),which re-emerged as a menace to cotton crops during the cotton cropping season 2017–2018 due to resistance development against Bt-cotton.A reasonably good number of predatory arthropods,including coccinellids,lacewings,and spiders,were found actively preying on the arthropod pest complex of the cotton crop during the early vegetative growth stage.Linear regression indicates a significant relationship between green boll infestations and pink bollworm moths in pheromone traps.Multiple linear regression analyse showed mean weekly weather at one-or two-week lag periods had a significant impact on sucking pest population(cotton aphid,cotton jassid,cotton whitefly,and onion thrips)fluctuation.Gossypium hirsutum cultivars RCH 2 and DCH 32,and G.barbadense cultivar Suvin were found susceptible to cotton jassid and onion thrips.Phule Dhanvantary,an G.arboreum cotton cultivar,demonstrated the highest tolerance among all evaluated cultivars against all sucking pests.Conclusion These findings have important implications for pest management in cotton crops.Susceptible cultivars warrant more attention for plant protection measures,making them more input-intensive.The choice of appropriate cultivars can help minimize input costs,thereby increasing net returns for cotton farmers.
基金financially supported by the State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Efficient Development(33550000-22-ZC0613-0006)National Natural Science Foundation of China(42202133)+2 种基金CNPC Innovation Fund(2022DQ02-0106)Strategic Cooperation Technology Projects of the CNPC and CUPB(ZLZX2020-01-05)Key Laboratory of Tectonics and Petroleum Resources(China University of Geosciences),Ministry of Education,China(TPR-2023-05)。
文摘Alkaline lacustrine shale is highly heterogeneous,and the complex relationship between the organicinorganic porosity network and hydrocarbon occurrence restricts the effectiveness of shale oil exploration and development.Herein,we investigated the Fengcheng Formation(P_(1)f)in Mahu Sag.This study integrated geochemistry,Soxhlet extraction,scanning electron microscopy,gas adsorption,and nuclear magnetic resonance T_(1)-T_(2)spectroscopy to elucidate the microscopic oil occurrence mechanisms in shales.Results indicate the presence of felsic shale,dolomitic shale,lime shale,and mixed shale within the P_(1)f.Matrix pores and microfractures associated with inorganic minerals are the predominant pore types in P_(1)f.Adsorbed oil primarily resides on the surfaces of organic matter and clay minerals,while free oil predominantly occupies inorganic pores and microfractures with larger pore sizes.Variations exist in the quantity and distribution of shale oil accumulation across different scales,where free oil and adsorbed oil are governed by dominant pores with diameters exceeding 10 nm and ineffective pores with diameters below 10 nm,respectively.Shale oil occurrence characteristics are influenced by organic matter,pore structure,and mineral composition.Felsic shale exhibits a high abundance of dominant pores,possesses the highest oil content,predominantly harbors free oil within these dominant pores,and demonstrates good mobility.Fluid occurrence in dolomitic shale and lime shale is intricate,with low oil content and a free oil to adsorbed oil ratio of 1:1.Mixed shale exhibits elevated clay mineral content and a scarcity of dominant pores.Moreover,ineffective pores contain increased bound water,resulting in medium oil content and limited mobility predominantly due to adsorption.Presently,shale oil mainly occurs in the dominant pores with a diameter larger than 10 nm in a free state.During the exploration and development of alkaline lacustrine shale oil resources,emphasis should be placed on identifying sweet spots within the felsic shale characterized by dominant pores.
基金supported by the National Natural Science Foundation of China(Nos.U24A2088,42177130,42277174,and 42477166).
文摘As coal mining depth increases,the combined effects of high stress,mining stress,and fault structures make dynamic impact hazards more frequent.The reproduction of dynamic impact phenomena is basis for studying their occurrence patterns and control mechanisms.Physical simulation test represents an efficacious methodology.However,there is currently a lack of simulation devices that can effectively simulate two types of dynamic impact phenomena,including high stress and fault slip dynamic impact.To solve aforementioned issues,the physical simulation test system for dynamic impact in deep roadways developed by authors is employed to carry out comparative tests of high stress and fault slip dynamic impact.The phenomena of high stress and fault slip dynamic impact are reproduced successfully.A comparative analysis is conducted on dynamic phenomena,stress evolution,roadway deformation,and support force.The high stress dynamic impact roadway instability mode,which is characterized by the release of high energy accompanied by symmetric damage,and the fault slip dynamic impact roadway instability mode,which is characterized by the propagation of unilateral stress waves accompanied by asymmetric damage,are clarified.On the basis,the differentiated control concepts for different types of dynamic impact in deep roadways are proposed.
基金supported by the National Natural Science Foundation of China(52304021,52104022,52204031)the Natural Science Foundation of Sichuan Province(2022NSFSC0205,2024NSFSC0201,2023NSFSC0947)the National Science and Technology Major Projects of China(2017ZX05049006-010).
文摘The global energy demand is increasing rapidly,and it is imperative to develop shale hydrocarbon re-sources vigorously.The prerequisite for enhancing the exploitation efficiency of shale reservoirs is the systematic elucidation of the occurrence characteristics,flow behavior,and enhanced oil recovery(EOR)mechanisms of shale oil within commonly developed nanopores.Molecular dynamics(MD)technique can simulate the occurrence,flow,and extraction processes of shale oil at the nanoscale,and then quantitatively characterize various fluid properties,flow characteristics,and action mechanisms under different reservoir conditions by calculating and analyzing a series of MD parameters.However,the existing review on the application of MD simulation in shale oil reservoirs is not systematic enough and lacks a summary of technical challenges and solutions.Therefore,recent MD studies on shale oil res-ervoirs were summarized and analyzed.Firstly,the applicability of force fields and ensembles of MD in shale reservoirs with different reservoir conditions and fluid properties was discussed.Subsequently,the calculation methods and application examples of MD parameters characterizing various properties of fluids at the microscale were summarized.Then,the application of MD simulation in the study of shale oil occurrence characteristics,flow behavior,and EOR mechanisms was reviewed,along with the elucidation of corresponding micro-mechanisms.Moreover,influencing factors of pore structure,wall properties,reservoir conditions,fluid components,injection/production parameters,formation water,and inorganic salt ions were analyzed,and some new conclusions were obtained.Finally,the main challenges associated with the application of MD simulations to shale oil reservoirs were discussed,and reasonable prospects for future MD research directions were proposed.The purpose of this review is to provide theoretical basis and methodological support for applying MD simulation to study shale oil reservoirs.
基金Supported by 2024 Red Imported Fire Ant Prevention and Control Project of Huizhou City.
文摘The prevalence of Solenopsis invicta is associated with habitat diversity,with a preference for various habitats ranked in the following order:ponds,wastelands,green belts,roads,parks,farmlands,and villages.Consequently,management strategies should be tailored to each habitat.There are two occurrence peaks of S.invicta throughout the year,specifically from March to April and from September to October.It is essential to emphasize prevention and control measures during the active periods of S.invicta.To enhance the effectiveness of these measures,supplementary control should be implemented within 10-15 d following the initial prevention and control efforts.Furthermore,the efficacy of prevention and control is notably higher on the second to third day immediately following rainfall.This study aimed to evaluate the efficacy of various agents in controlling S.invicta.A comparative analysis was conducted on the efficacy of three different brands of agents against S.invicta.The findings indicated that a concentration of 0.08%-0.10%indoxacarb exhibited a comparable extermination effect on S.invicta worker ants.However,agents with larger particle sizes demonstrated a reduced efficacy in exterminating S.invicta nests.
基金The Fund of Laoshan Laboratory under contract No.LSKJ202203602the National key R&D Program of China under contract No.2022YFC2803600the Taishan Scholarship from Shandong Province.
文摘To explore the geochemical characteristics and genesis of the elements in ferromanganese nodules from the Northwest Pacific,this study analyses the mineral composition,elemental content,occurrence phase and genetic mechanisms of samples by X-ray diffraction(XRD),inductively coupled plasma-optical emission spectrometry(ICP-OES),inductively coupled plasma-mass spectrometry(ICP-MS)and phase analysis methods.The results show that ferromanganese nodules are mainly hydrogenetic,and Mn/Fe content ratio ranges from 0.95 to 2.05.The major minerals are vernadite(δ-MnO_(2))and amorphous ferric oxyhydroxide(FeOOH),and the secondary minerals include todorokite,birnessite,quartz and plagioclase.Ferromanganese nodules contain high contents of Co(0.24%-0.42%),Cu(0.23%-0.73%),Ni(0.33%-0.86%)and rare earth elements(REEs,1192-1990μg/g),which have positive Ce and negative Y anomalies but no Eu anomaly.A cluster analysis suggests that the elements in ferromanganese nodules can be divided into three groups:hydrogenetic components,including Fe,Ti,Zr,P,Pb,Co,Ba,Sr,V and REEs;diagenetic components,including Mn,Ni,Mg,Zn and Cu;and detrital components,including Al,Na,K and Ca.According to chemical leaching,ferromanganese nodules can be divided into four phases:Na,Ca,Mg and Sr are mainly enriched in the carbonate phase;Mn,Co,Ni and Ba are mainly enriched in the Mn-oxide phase;Fe,P,Ti,Cu,Pb,V,Zn,Zr and REEs are mainly enriched in the Fe-oxide phase;and Al and K are mainly enriched in the residual phase.A combination of the two different methods reveal selective enrichment of metal elements from seawater by ferromanganese nodules,featuring multisource mineralization.Moreover,through ion exchange and adsorption,approximately 71.2%of REEs are enriched in the Fe-oxide phase,15.4%in the Mn-oxide phase and 12.4%in the residual phase,while REE contents in the carbonate phase are relatively low.In addition,under the oxic conditions of seawater,the oxidation of soluble Ce^(3+)to insoluble CeO_(2)together with Fe-Mn minerals results in Ce enrichment in ferromanganese nodules.This study provides a reference for the metallogenesis of ferromanganese nodules from the Northwest Pacific.
文摘The annual average number of snowstorm days in Tongliao area is 1-3 d.Snowstorms mainly happen from October to next May,peaking from December to next March.The incidence is the highest between 12:00 and 15:00.The Mongolian low vortex is the main weather system that triggers snowstorms,and can be classified into three types:small trough development,horizontal trough becoming vertical,and low trough moving eastwards.Snowstorms pose a relatively serious threat to agricultural and animal husbandry production,transportation,power and communication in Tongliao.Especially in spring,snowstorm weather poses a greater threat to agriculture and animal husbandry in Tongliao.It is needed to pay attention to the impact of extreme weather and climate events such as snowstorms,strengthen research on the mechanisms of disaster-causing weather,enhance the early warning capability of disasters,and provide good service guarantees for low-temperature weather in winter.
基金Supported by National Natural Science Foundation of China,No.81903398the Research Start-Up Fund for the Introduction of Talents of Sichuan University,No.YJ2021112+4 种基金Medical Youth Innovation Research Project of Sichuan Province,No.Q21016Natural Science Foundation of Sichuan,No.2023NSFSC1927“From 0 to 1”Innovation Project,Sichuan University,No.2023SCUH0026Sichuan Provincial Science and Technology Department 2023 Central Guide Local Project,No.2023ZYD0097Cigar Fermentation Technology Key Laboratory of Tobacco Industry,No.20202309BC530.
文摘BACKGROUND The intestinal flora(IF)has been linked to risks of non-communicable diseases,especially various cancers,stroke,and Alzheimer’s disease.However,many uncertainties of these associations during different stages of growth,deve-lopment,and aging still exist.Therefore,further in-depth explorations are warranted.AIM To explore the associations of the human IF with disease risks during different stages of growth,development,and aging to achieve more accurate and con-vincing conclusions.METHODS Cohort,cross-sectional,case-control,and Mendelian randomization studies published in the PubMed and Web of Science databases until December 31,2023 were systematically reviewed to clarify the associations of the IF at the genus level with the risks of various non-communicable diseases,which were grouped in accordance with the 10^(th) revision of the International Classification of Diseases.RESULTS In total,57 studies were included to quantitatively examine the influence of the IF on the risks of 30 non-communicable diseases during different stages of growth,development,and aging.Population studies and Mendelian randomization studies confirmed positive associations of the abundances of Bifidobacterium and Ruminococcus with multiple sclerosis.CONCLUSION These findings contribute to a deeper understanding of the roles of the IF and provide novel evidence for effective strategies for the prevention and treatment of non-communicable diseases.In the future,it will be necessary to explore a greater variety of research techniques to uncover the specific mechanisms by which gut microbiota trigger diseases and conduct in-depth studies on the temporal relationship between microbiota alterations and diseases,so as to clarify the causal relationship more accurately.
基金supported by the National Natural Science Foundation of China(No.22225605)the National Key Research and Development Program of China(No.2023YFC3706600)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB0750200).
文摘The number of newborns born with diseases is increasing recently.Thyroid hormones(THs)are closely related to the growth and development of the newborn in the mother's womb and to the carriage of related diseases after birth.Environmental endocrine-disrupting compounds(EDCs)have been proven to harm THs in newborns.Phthalates(PAEs),a typical class of EDCs,are commonly used in toys,childcare materials,and food contact materials,which have been closely connected with neonatal thyroid dysfunction and thyroid-related diseases.As restrictions on PAEs becomemore stringent in neonatal field,numerous PAE alternatives are emerging.Associations between exposure to PAEs and their alternatives and dysfunctions in THs have been explored.Hence,we summarized the body burdens and regional characteristics of PAEs and their alternatives in neonatal urine,cord blood,and meconium.Subsequently,the influences of PAEs and their alternatives on thyroid dysfunction,prematurity,low birth weight,fetal growth restriction,respiratory dysfunction,immune disorders,neurological disorders,and reproductive disorders in newborns were evaluated.Furthermore,we scrutinized the effects of PAEs and their alternatives on the neonatal thyroid from signaling,substance transport,and hormone production to explore the underlying mechanisms of action on neonatal thyroid and thyroid-related disorders.As the declining global trends of healthy newborns and the potential impacts of PAEs and their alternatives on thyroid function,a more comprehensive study is needed to discuss their effects on newborns and their underlying mechanisms.This review facilitates attention to the effects of PAEs and their alternatives on thyroid and thyroid-related disorders in newborns.
