As NPC performances surge in popularity,destinations are recruiting actors and building story-driven scenes to reinvent traditional tourism Eight days,seven cities-a whirlwind tour that defined actor Zheng Guolin’s w...As NPC performances surge in popularity,destinations are recruiting actors and building story-driven scenes to reinvent traditional tourism Eight days,seven cities-a whirlwind tour that defined actor Zheng Guolin’s work schedule during the National Day holiday a month ago.From 1 to 8 October,he maintained a relentless pace,not just logging miles but also switching between roles.展开更多
Gas-bearing shales have become a major source of future natural gas production worldwide.It has become increasingly urgent to develop a reliable prediction model and corresponding workflow for identifying shale gas sw...Gas-bearing shales have become a major source of future natural gas production worldwide.It has become increasingly urgent to develop a reliable prediction model and corresponding workflow for identifying shale gas sweet spots.The formation of gas-bearing shales is closely linked to relative sealevel changes,providing an important approach to predicting sweet spots in the Wufeng-Longmaxi shale in the southern Sichuan Basin,China.Three types of marine shale gas sweet spots are identified in the shale based on their formation stages combined with relative sea-level changes:early,middle,and late transgression types.This study develops a prediction model and workflow for identifying shale gas sweet spots by analyzing relative sea-level changes and facies sequences.Predicting shale gas sweet spots in an explored block using this model and workflow can provide a valuable guide for well design and hydraulic fracturing,significantly enhancing the efficiency of shale gas exploration and development.Notably,the new prediction model and workflow can be utilized for the rapid evaluation of the potential for shale gas development in new shale gas blocks or those with low exploratory maturity.展开更多
In the present paper, the theoretical frame work of magneto hydrodynamics (MHD) is used to give a solution of the problem about the origin, persistence and disappearance of the Sunspots;as well as their tendency to ap...In the present paper, the theoretical frame work of magneto hydrodynamics (MHD) is used to give a solution of the problem about the origin, persistence and disappearance of the Sunspots;as well as their tendency to appear as bipolar magnetic couples. According to the results obtained, a possible explanation about the change of polarity in both solar hemispheres is given. Heuristic but logical arguments about the periodicity of the phenomenon of the observed magnetic polarity and the tendency of couples of Sunspots to appear solely in certain latitudes that can be called tropical regions of the Sun are presented. Finally, an indirect experimental test is proposed to show the possible process that produces the polarity of the Sunspots in a given cycle, as well as the invertion of that polarity in the next solar cycle.展开更多
Experimental validation of laser intensity is particularly important for the study of fundamental physics at extremely high intensities.However,reliable diagnosis of the focal spot and peak intensity faces huge challe...Experimental validation of laser intensity is particularly important for the study of fundamental physics at extremely high intensities.However,reliable diagnosis of the focal spot and peak intensity faces huge challenges.In this work,we demonstrate for the firs time that the coherent radiation farfiel patterns from laser–foil interactions can serve as an in situ,real-time,and easy-to-implement diagnostic for an ultraintense laser focus.The laser-driven electron sheets,curved by the spatially varying laser fiel and leaving the targets at nearly the speed of light,produce doughnut-shaped patterns depending on the shapes of the focal spot and the absolute laser intensities.Assisted by particle-in-cell simulations,we can achieve measurements of the intensity and the focal spot,and provide immediate feedback to optimize the focal spots for extremely high intensity.展开更多
Barn swallows Hirundo rustica have white spots on their tail feathers, and they have been hypothe-sized to be a handicap because white spots are prone to feather breakage, ectoparasites are dispro-portionately common ...Barn swallows Hirundo rustica have white spots on their tail feathers, and they have been hypothe-sized to be a handicap because white spots are prone to feather breakage, ectoparasites are dispro-portionately common in white spots, and size of white spots increases with tail length. Here I testfor attractiveness of narrow and long tail spots by manipulation of their shape while using com-plete painting of spots and an absence of treatment as a control. Female barn swallows are knownto differentially invest in reproduction when mated to attractive males. Spot manipulation tookplace during laying of the first clutch, and there were no effects of treatment on clutch size or broodsize of first or second broods. In contrast, the incidence of second clutches and the total number ofeggs and fledglings produced during the breeding season was larger in males with painting of theside of tail spots rather than painting of the tip of spots, painting of entire spots, or no treatment.These findings are consistent with the hypothesis that it is the shape rather than the size of tailspots that affects differential reproductive effort by female barn swallows.展开更多
There is a huge amount of marine shale gas resources in the southern Sichuan Basin in China, and most of the resources are at the buried depth of 3500</span><span style="font-family:""> <...There is a huge amount of marine shale gas resources in the southern Sichuan Basin in China, and most of the resources are at the buried depth of 3500</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:Verdana;">4500 meters. At present, deep shale gas is in the early stage of exploration and development. In order to achieve large-scale efficient development, in addition to optimizing favorable blocks, it is also to identify the optimal target in the vertical direction combine geology, drilling, and fracturing. Therefore, Taking the Longmaxi formation shale in the Luzhou block as the research object, based on drilling, logging, and core experiment data, through single well and 3D geomechanical modeling methods, analyze the characteristics of organic matter abundance, porosity, pore pressure, collapse pressure, mineral composition and in-situ stress of different layers of shale in Longmaxi formation. Systematically summarized the main controlling factors of the “sweet spot” of deep shale gas and establish the comprehensive evaluation system of deep shale gas “sweet spots”, to clarify the optimal “sweet spots” of geology, drilling, and fracturing in the Longmaxi reservoir. Results show that the total organic carbon content, porosity, and gas saturation of the long111 layer are higher than other layers. The Long111 layer has a low collapse pressure and a high compressive strength, the risk of wellbore instability is relatively low. The stress difference coefficient of All layers is less than 0.3, and the brittleness index of the Long111 layer is 62.35%. A complex fracture network is easier to form after fracturing. The conclusion shows that the Long111 layer is the optimal reservoir section of the Longmaxi Formation. Ensure the drilled rate of the Long111 layer and maximize the length of the horizontal section can obtain higher production.展开更多
Economic shale gas production requires hydraulic fracture stimulation to increase the formation permeability. Hydraulic fracturing strongly depends on geomechanical parameters such as Young＇s modulus and Poisson＇s r...Economic shale gas production requires hydraulic fracture stimulation to increase the formation permeability. Hydraulic fracturing strongly depends on geomechanical parameters such as Young＇s modulus and Poisson＇s ratio. Fracture-prone sweet spots can be predicted by prestack inversion, which is an ill-posed problem; thus, regularization is needed to obtain unique and stable solutions. To characterize gas-bearing shale sedimentary bodies, elastic parameter variations are regarded as an anisotropic Markov random field. Bayesian statistics are adopted for transforming prestack inversion to the maximum posterior probability. Two energy functions for the lateral and vertical directions are used to describe the distribution, and the expectation-maximization algorithm is used to estimate the hyperparameters of the prior probability of elastic parameters. Finally, the inversion yields clear geological boundaries, high vertical resolution, and reasonable lateral continuity using the conjugate gradient method to minimize the objective function. Antinoise and imaging ability of the method were tested using synthetic and real data.展开更多
A study of the accessibility of a city’s scenic spots via different travel modes can contribute to optimization of tourism-related transportation while improving tourists’ travel-related satisfaction levels and adva...A study of the accessibility of a city’s scenic spots via different travel modes can contribute to optimization of tourism-related transportation while improving tourists’ travel-related satisfaction levels and advancing tourism. We systematically analyzed the accessibility of 56 scenic spots in Xi’an City, China, via car and public transport travel modes using the real-time travel function of the Baidu Maps API(Application Programming Interface) along with spatial analysis methods and the modal accessibility gap index of scenic spots. We obtained the following results. First, maximum and minimum travel times using public transport exceeded those using cars. Moreover, the accessibility of scenic spots via cars and public transport presented a circular spatial pattern of increasing travel time from the center to the periphery. Contrasting with travel by public transport, car travel showed a clear time-space compression effect. Second, accessibility of the scenic spots via cars and public transport showed some spatial heterogeneity, with no clear advantages of car accessibility in the central urban area. However, advantages of car accessibility were increasingly evident moving from the center to the periphery. Third, whereas the correlation of the modal accessibility gap index of scenic spots in Xi’an with global space was significantly positive, local spatial interdependence was only evident in some inner city areas and in marginal areas. Moreover, spatial heterogeneity was evident in two regions but was insignificant in other areas, indicating that the spatial interdependence of the modal accessibility gap index in most scenic spots was not apparent in terms of the overall effect of public transport routes, road networks, and the distribution of scenic spots. The improvement of public transport coverage in marginal areas and the optimization of public transport routes in central urban areas are essential tasks for improving travel using public transport in the future.展开更多
Direct infusion mass spectrometry(DIMS) is a powerful technique in clinical diagnosis for screening neonatal amino acid metabolic disorders from dried blood spots(DBS).However,DIMS sometimes generated false-positive r...Direct infusion mass spectrometry(DIMS) is a powerful technique in clinical diagnosis for screening neonatal amino acid metabolic disorders from dried blood spots(DBS).However,DIMS sometimes generated false-positive results for analysis of amino acids.In this work,we utilized a stable isotope derivatization method,combining with liquid chromatography tandem mass spectrometry(SID-LC-MS),to improve the specificity for screening amino acids in DBS specimens.A pair of isotope reagents,p-(dimethylamino)phenyl isothiocyanate(DMAP-NCS) and 4-isothiocyanato-N,N-bis(methyl-[2H2])aniline([2H4]DMAP-NCS),was synthesized and used to label amino acids in DBS specimens.The [2H4]DMAP-NCS labelled amino acid standards were used as internal standards to compensate the matrix effect.This method was validated by measuring linearity,recovery and accuracy.The results showed that the developed SID-LC-MS method can be used for sensitive and selective determination of 12 diagnostically important amino acids in DBS specimens.展开更多
Microwave heating can rapidly and uniformly raise the temperature and accelerate the reaction rate.In this paper,microwave heating was used to improve the acid leaching,and the mechanism was investigated via microscop...Microwave heating can rapidly and uniformly raise the temperature and accelerate the reaction rate.In this paper,microwave heating was used to improve the acid leaching,and the mechanism was investigated via microscopic morphology analysis and numerical simulation by COMSOL Multiphysics software.The effects of the microwave power,leaching temperature,CaF_(2) dosage,H_(2)SO_(4) concentration,and leaching time on the vanadium recovery were investigated.A vanadium recovery of 80.66%is obtained at a microwave power of 550 W,leaching temperature of 95℃,CaF_(2) dosage of 5wt%,H_(2)SO_(4) concentration of 20vol%,and leaching time of 2.5 h.Compared with conventional leaching technology,the vanadium recovery increases by 6.18%,and the leaching time shortens by 79.17%.More obvious pulverization of shale particles and delamination of mica minerals happen in the microwave-assisted leaching process.Numerical simulation results show that the temperature of vanadium shales increases with an increase in electric field(E-field).The distributions of E-field and temperature among vanadium shale particles are relatively uniform,except for the higher content at the contact position of the particles.The analysis results of scaleup experiments and leaching experiments indicate high-temperature hot spots in the process of microwave-assisted leaching,and the local high temperature destroys the mineral structure and accelerates the reaction rate.展开更多
After analysis of connotation of low-carbon scenic spots,the paper considered that a perfect low-carbon scenic spot is a comprehensive integrity with satisfying tourists' lowest tourist experience effect as the pr...After analysis of connotation of low-carbon scenic spots,the paper considered that a perfect low-carbon scenic spot is a comprehensive integrity with satisfying tourists' lowest tourist experience effect as the premise and with low energy consumption,low pollution and low emission as the foundation.Low-carbon tourist scenic spots had been classified into three types which are ecological type,cultural type and coupling type of ecology and culture.Representatives of each type of tourist scenic spot were illustrated.It proposed that government should play the leading role in cultivation of low-carbon scenic spot;tourism industry should enhance self supervision;tourism development mode should be transformed and upgrading of tourist products should be realized.By taking Yuntai Mountain Scenic Area of Henan Province for example,based on low-carbon tourist resources,low-carbon development of management,following measures realizing low-carbon economy were put forward:① purifying air quality and beautifying environment of scenic area;② sifting laggard productivity and protecting ecological resources in the scenic area by many means;③ sticking to low-carbon environmental protection concept and completing infrastructure service;④ developing tourist native products and souvenirs based on local resources;⑤ applying electronic access control ticket system,intelligent monitor system and LED information and communication platform,so as to achieve low-carbon management.展开更多
By taking the twelve scenic spots in Ancient Lotus Pond Garden as study objects, they have been introduced and their names have been classified in accordance with allege and symbol nomenclature, linguistic rhetoric no...By taking the twelve scenic spots in Ancient Lotus Pond Garden as study objects, they have been introduced and their names have been classified in accordance with allege and symbol nomenclature, linguistic rhetoric nomenclature, narration and description nomenclature, and emotion-endowing and ambition-expressing nomenclature adopted in related articles. Then, the cultural connotations of these scenic spots have been summarized, and Confucian thought and Taoist thought contained in "Surge Including Pavilion" and "High Principle Tower" have been analyzed. The research is aimed at enlightening modern garden workers through illustrating the connotation of the names of scenic spots, so that they can be inspired in the naming process.展开更多
Cereal crops, including wheat, barley, oats, rye, etc., are the major sources of calories and proteins for most of the people in the world as well as in China. Cereal rusts and powdery mildews are very important disea...Cereal crops, including wheat, barley, oats, rye, etc., are the major sources of calories and proteins for most of the people in the world as well as in China. Cereal rusts and powdery mildews are very important diseases occurred on the cereal crops, which caused yield losses at 5-10% in general and even more than 30% while severe epidemics occurred. In recent years, with the global climate change, change of cultivation system and evolution of the pathogens, the world is facing great challenges caused by cereal diseases.展开更多
The Chang-63 reservoir in the Huaqing area has widely developed tight sandstone ＂thick sand layers, but not reservoirs characterized by rich in oil＂, and it is thus necessary to further study its oil and gas enrichm...The Chang-63 reservoir in the Huaqing area has widely developed tight sandstone ＂thick sand layers, but not reservoirs characterized by rich in oil＂, and it is thus necessary to further study its oil and gas enrichment law. This study builds porosity and fracture development and evolution models in different deposition environments, through core observation, casting thin section, SEM, porosity and permeability analysis, burial history analysis, and ＂four-property-relationships＂ analysis.展开更多
In China, many scenic and tourism areas are suffering from the urbanization that results from physical development of tourism projects, leading to the removal of the vegetative cover, the creation of areas impermeable...In China, many scenic and tourism areas are suffering from the urbanization that results from physical development of tourism projects, leading to the removal of the vegetative cover, the creation of areas impermeable to water, in-stream modifications, and other problems. In this paper, the risk of soil erosion and its ecological risks in the West Lake Scenic Spots （WLSS） area were quantitatively evaluated by integrating the revised universal soil loss equation （RUSLE） with a digital elevation model （DEM） and geographical information system （GIS） software. The standard RUSLE factors were modified to account for local climatic and topographic characteristics reflected in the DEM maps, and for the soil types and vegetation cover types. An interface was created between the Areinfo software and RUSLE so that the level of soil erosion and its ecological risk in the WLSS area could be mapped immediately once the model factors were defined for the area. The results from an analysis using the Areinfo-RUSLE interface showed that the risk value in 93 % of the expanding western part of the WLSS area was moderate or more severe and the soil erosion risk in this area was thus large compared with that in the rest of the area. This paper mainly aimed to increase the awareness of the soil erosion risk in urbanizing areas and suggest that the local governments should consider the probable ecological risk resulting from soil erosion when enlarging and developing tourism areas.展开更多
BACKGROUND Colorectal cancer(CRC)is the third most common cancer worldwide and the second leading cause of cancer-related death.Over the past two decades,numerous researchers have provided important evidence regarding...BACKGROUND Colorectal cancer(CRC)is the third most common cancer worldwide and the second leading cause of cancer-related death.Over the past two decades,numerous researchers have provided important evidence regarding the role of tight junction(TJ)proteins in the occurrence and progression of CRC.The causal relationship between the presence of specific TJ proteins and the development of CRC has also been confirmed.Despite the large number of publications in this field,a bibliometric study to review the current state of research and highlight the research trends and hotspots in this field has not yet been performed.AIM To analyze research on TJs and CRC,summarize the field’s history and current status,and predict future research directions.METHODS We searched the Science Citation Index Expanded database for all literature on CRC and TJs from 2001-2023.We used bibliometrics to analyze the data of these papers,such as the authors,countries,institutions,and references.Co-authorship,co-citation,and co-occurrence analyses were the main methods of analysis.CiteSpace and VOSviewer were used to visualize the results.RESULTS A total of 205 studies were ultimately identified.The number of publications on this topic has steadily increased since 2007.China and the United States have made the largest contributions to this field.Anticancer Research was the most prolific journal,publishing 8 articles,while the journal Oncogene had the highest average citation rate(68.33).Professor Dhawan P was the most prolific and cited author in this field.Co-occurrence analysis of keywords revealed that“tight junction protein expression”,“colorectal cancer”,“intestinal microbiota”,and“inflammatory bowel disease”had the highest frequency of occurrence,revealing the research hotspots and trends in this field.CONCLUSION This bibliometric analysis evaluated the scope and trends of TJ proteins in CRC,providing valuable research perspectives and future directions for studying the connection between the two.It is recommended to focus on emerging research hotspots,such as the correlations among intestinal microbiota,inflammatory bowel disease,TJ protein expression,and CRC.展开更多
Petrographic comparison of andalusite in the contact aureole of the Fangshan pluton, Zhoukoudian, Beijing, China, and hornfels in the aureole of the Markfield diorite, Leicestershire, Eng- land, shows that spots chara...Petrographic comparison of andalusite in the contact aureole of the Fangshan pluton, Zhoukoudian, Beijing, China, and hornfels in the aureole of the Markfield diorite, Leicestershire, Eng- land, shows that spots characteristic of the outer zones of contact metamorphic aureoles did not form during the progressive stage of contact metamorphism, but are pseudomorphs after earlier andalusite with characteristic chiastolite microstructure. The baked margin produced by contact metamorphism of syenite against a dyke in the Houshihushan ring complex, Shanhaiguan, Hebei Province, China, is an unusual feature caused by the dyke＇s role as a feeder to a family of cone-sheets.展开更多
The shale gas accumulation conditions in the basin-margin transition zone of southeastern Chongqing in SW China are complex.In order to improve single-well productivity in this area,the geologic characteristics,major ...The shale gas accumulation conditions in the basin-margin transition zone of southeastern Chongqing in SW China are complex.In order to improve single-well productivity in this area,the geologic characteristics,major factors controlling the occurrence of sweet spots,and drilling/fracturing optimization were investigated in this study.The sweet spot evaluation system and criteria were established,and the horizontal-well-design technology was developed.The following three conclusions were drawn.First,the accumulation and high-productivity-oriented approaches for sweet spot evaluation are proposed and the criteria are established based on screened key indicators.Second,the horizontal well was designed based on:(1)the“six-map”method,to identify both the geology and engineering sweet spots for well locations;and(2)seismic attributes,to predict the development of fractures and cavities,and thus,avoid mud loss and improve the drilling efficiency.The target window,well-azimuth optimization,and the curvature were forecasted to improve the fracturing performances.Third,the Pingqiao anticline,Dongsheng anticline,Jinfo slope,and Wulong syncline were selected as Type I sweet spots.Currently,shale gas has been successfully discovered in the basin-margin transition zone and is being commercially developed.展开更多
Background:Brood parasitic birds such as cuckoos(Cuculus spp.)can reduce their host’s reproductive success.Such selection pressure on the hosts has driven the evolution of defense behaviors such as egg rejection agai...Background:Brood parasitic birds such as cuckoos(Cuculus spp.)can reduce their host’s reproductive success.Such selection pressure on the hosts has driven the evolution of defense behaviors such as egg rejection against cuckoo parasitism.Studies have shown that Cinereous Tits(Parus cinereus)in China have a good ability for recognizing foreign eggs.However,it is unclear whether egg spots play a role in egg recognition.The aims of our study were to investigate the egg recognition ability of two Cinereous Tit populations in China and to explore the role of spots in egg recognition.Methods:To test the effect of eggshell spots on egg recognition,pure white eggs of the White-rumped Munia(Lonchura striata)and eggs of White-rumped Munia painted with red brown spots were used to simulate experimental parasitism.Results:Egg experiments showed that Cinereous Tits rejected 51.5%of pure white eggs of the White-rumped Munia,but only 14.3%of spotted eggs of the White-rumped Munia.There was a significant difference in egg recognition and rejection rate between the two egg types.Conclusions:We conclude that eggshell spots on Cinereous Tit eggs had a signaling function and may be essential to tits for recognizing and rejecting parasitic eggs.展开更多
The cathode spots are a common phenomenon in the TIG(tungsten inert gas)welding process.However,it is rarely observed in the activating TIG welding process.This research is mainly focused on the effect of activating f...The cathode spots are a common phenomenon in the TIG(tungsten inert gas)welding process.However,it is rarely observed in the activating TIG welding process.This research is mainly focused on the effect of activating flux on cathode spots in the activating TIG welding.The characteristics and behaviors of cathode spots were investigated in activating TIG welding by the high-speed camera and the spectrograph.Three kinds of oxide(TiO_(2),SiO_(2),MnO_(2))and two halide(MnCl_(2),CaF_(2))activating fluxes are used in the activating TIG welding process.The results show that differ from the TIG welding,the oxide activating flux increases the number of cathode spots and decreases the velocity.The effect is the opposite for the halide activating flux.Moreover,the number of spots no longer varies with the current except TiO2 activating flux.As the temperature of the weld pool surface increases the spot moves away from the center.But this rule is not valid when silica and manganese compounds activating fluxes are used.The variation of cathode spots is caused by the oxide film reformed and the distribution of weld slag.The formation mechanism of cathode spots might be the impact of ions on the cathode surface and the strong electric field formed near the cathode surface.展开更多
文摘As NPC performances surge in popularity,destinations are recruiting actors and building story-driven scenes to reinvent traditional tourism Eight days,seven cities-a whirlwind tour that defined actor Zheng Guolin’s work schedule during the National Day holiday a month ago.From 1 to 8 October,he maintained a relentless pace,not just logging miles but also switching between roles.
文摘Gas-bearing shales have become a major source of future natural gas production worldwide.It has become increasingly urgent to develop a reliable prediction model and corresponding workflow for identifying shale gas sweet spots.The formation of gas-bearing shales is closely linked to relative sealevel changes,providing an important approach to predicting sweet spots in the Wufeng-Longmaxi shale in the southern Sichuan Basin,China.Three types of marine shale gas sweet spots are identified in the shale based on their formation stages combined with relative sea-level changes:early,middle,and late transgression types.This study develops a prediction model and workflow for identifying shale gas sweet spots by analyzing relative sea-level changes and facies sequences.Predicting shale gas sweet spots in an explored block using this model and workflow can provide a valuable guide for well design and hydraulic fracturing,significantly enhancing the efficiency of shale gas exploration and development.Notably,the new prediction model and workflow can be utilized for the rapid evaluation of the potential for shale gas development in new shale gas blocks or those with low exploratory maturity.
文摘In the present paper, the theoretical frame work of magneto hydrodynamics (MHD) is used to give a solution of the problem about the origin, persistence and disappearance of the Sunspots;as well as their tendency to appear as bipolar magnetic couples. According to the results obtained, a possible explanation about the change of polarity in both solar hemispheres is given. Heuristic but logical arguments about the periodicity of the phenomenon of the observed magnetic polarity and the tendency of couples of Sunspots to appear solely in certain latitudes that can be called tropical regions of the Sun are presented. Finally, an indirect experimental test is proposed to show the possible process that produces the polarity of the Sunspots in a given cycle, as well as the invertion of that polarity in the next solar cycle.
基金supported by the Guangdong High Level Innovation Research Institute(Grant No.2021B0909050006)the National Grand Instrument Project(Grant No.2019YFF01014402)+1 种基金the National Natural Science Foundation of China(Grant No.12205008)support from the National Science Fund for Distinguished Young Scholars(Grant No.12225501)。
文摘Experimental validation of laser intensity is particularly important for the study of fundamental physics at extremely high intensities.However,reliable diagnosis of the focal spot and peak intensity faces huge challenges.In this work,we demonstrate for the firs time that the coherent radiation farfiel patterns from laser–foil interactions can serve as an in situ,real-time,and easy-to-implement diagnostic for an ultraintense laser focus.The laser-driven electron sheets,curved by the spatially varying laser fiel and leaving the targets at nearly the speed of light,produce doughnut-shaped patterns depending on the shapes of the focal spot and the absolute laser intensities.Assisted by particle-in-cell simulations,we can achieve measurements of the intensity and the focal spot,and provide immediate feedback to optimize the focal spots for extremely high intensity.
文摘Barn swallows Hirundo rustica have white spots on their tail feathers, and they have been hypothe-sized to be a handicap because white spots are prone to feather breakage, ectoparasites are dispro-portionately common in white spots, and size of white spots increases with tail length. Here I testfor attractiveness of narrow and long tail spots by manipulation of their shape while using com-plete painting of spots and an absence of treatment as a control. Female barn swallows are knownto differentially invest in reproduction when mated to attractive males. Spot manipulation tookplace during laying of the first clutch, and there were no effects of treatment on clutch size or broodsize of first or second broods. In contrast, the incidence of second clutches and the total number ofeggs and fledglings produced during the breeding season was larger in males with painting of theside of tail spots rather than painting of the tip of spots, painting of entire spots, or no treatment.These findings are consistent with the hypothesis that it is the shape rather than the size of tailspots that affects differential reproductive effort by female barn swallows.
文摘There is a huge amount of marine shale gas resources in the southern Sichuan Basin in China, and most of the resources are at the buried depth of 3500</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:Verdana;">4500 meters. At present, deep shale gas is in the early stage of exploration and development. In order to achieve large-scale efficient development, in addition to optimizing favorable blocks, it is also to identify the optimal target in the vertical direction combine geology, drilling, and fracturing. Therefore, Taking the Longmaxi formation shale in the Luzhou block as the research object, based on drilling, logging, and core experiment data, through single well and 3D geomechanical modeling methods, analyze the characteristics of organic matter abundance, porosity, pore pressure, collapse pressure, mineral composition and in-situ stress of different layers of shale in Longmaxi formation. Systematically summarized the main controlling factors of the “sweet spot” of deep shale gas and establish the comprehensive evaluation system of deep shale gas “sweet spots”, to clarify the optimal “sweet spots” of geology, drilling, and fracturing in the Longmaxi reservoir. Results show that the total organic carbon content, porosity, and gas saturation of the long111 layer are higher than other layers. The Long111 layer has a low collapse pressure and a high compressive strength, the risk of wellbore instability is relatively low. The stress difference coefficient of All layers is less than 0.3, and the brittleness index of the Long111 layer is 62.35%. A complex fracture network is easier to form after fracturing. The conclusion shows that the Long111 layer is the optimal reservoir section of the Longmaxi Formation. Ensure the drilled rate of the Long111 layer and maximize the length of the horizontal section can obtain higher production.
基金supported by CNPC fundamental research project(No.2014E-3204)
文摘Economic shale gas production requires hydraulic fracture stimulation to increase the formation permeability. Hydraulic fracturing strongly depends on geomechanical parameters such as Young＇s modulus and Poisson＇s ratio. Fracture-prone sweet spots can be predicted by prestack inversion, which is an ill-posed problem; thus, regularization is needed to obtain unique and stable solutions. To characterize gas-bearing shale sedimentary bodies, elastic parameter variations are regarded as an anisotropic Markov random field. Bayesian statistics are adopted for transforming prestack inversion to the maximum posterior probability. Two energy functions for the lateral and vertical directions are used to describe the distribution, and the expectation-maximization algorithm is used to estimate the hyperparameters of the prior probability of elastic parameters. Finally, the inversion yields clear geological boundaries, high vertical resolution, and reasonable lateral continuity using the conjugate gradient method to minimize the objective function. Antinoise and imaging ability of the method were tested using synthetic and real data.
基金Under the auspices of National Natural Science Foundation of China(No.41831284,41501120)Special Scientific Research Project of Education Department of Shaanxi Provincial Government(No.18JK0649)Scientific Research Project of Xi’an International Studies University(No.18XWC24)
文摘A study of the accessibility of a city’s scenic spots via different travel modes can contribute to optimization of tourism-related transportation while improving tourists’ travel-related satisfaction levels and advancing tourism. We systematically analyzed the accessibility of 56 scenic spots in Xi’an City, China, via car and public transport travel modes using the real-time travel function of the Baidu Maps API(Application Programming Interface) along with spatial analysis methods and the modal accessibility gap index of scenic spots. We obtained the following results. First, maximum and minimum travel times using public transport exceeded those using cars. Moreover, the accessibility of scenic spots via cars and public transport presented a circular spatial pattern of increasing travel time from the center to the periphery. Contrasting with travel by public transport, car travel showed a clear time-space compression effect. Second, accessibility of the scenic spots via cars and public transport showed some spatial heterogeneity, with no clear advantages of car accessibility in the central urban area. However, advantages of car accessibility were increasingly evident moving from the center to the periphery. Third, whereas the correlation of the modal accessibility gap index of scenic spots in Xi’an with global space was significantly positive, local spatial interdependence was only evident in some inner city areas and in marginal areas. Moreover, spatial heterogeneity was evident in two regions but was insignificant in other areas, indicating that the spatial interdependence of the modal accessibility gap index in most scenic spots was not apparent in terms of the overall effect of public transport routes, road networks, and the distribution of scenic spots. The improvement of public transport coverage in marginal areas and the optimization of public transport routes in central urban areas are essential tasks for improving travel using public transport in the future.
基金supported by the National Key R&D Program of China(No.2018YFA0900400)the National Natural ScienceFoundation of China(Nos.21635006,31670373,21721005,21904099)the Postdoctoral Science Foundation of China(No.2018M642893)。
文摘Direct infusion mass spectrometry(DIMS) is a powerful technique in clinical diagnosis for screening neonatal amino acid metabolic disorders from dried blood spots(DBS).However,DIMS sometimes generated false-positive results for analysis of amino acids.In this work,we utilized a stable isotope derivatization method,combining with liquid chromatography tandem mass spectrometry(SID-LC-MS),to improve the specificity for screening amino acids in DBS specimens.A pair of isotope reagents,p-(dimethylamino)phenyl isothiocyanate(DMAP-NCS) and 4-isothiocyanato-N,N-bis(methyl-[2H2])aniline([2H4]DMAP-NCS),was synthesized and used to label amino acids in DBS specimens.The [2H4]DMAP-NCS labelled amino acid standards were used as internal standards to compensate the matrix effect.This method was validated by measuring linearity,recovery and accuracy.The results showed that the developed SID-LC-MS method can be used for sensitive and selective determination of 12 diagnostically important amino acids in DBS specimens.
基金supported by the National Natural Science Foundation of China(No.51904211)the National Natural Science Foundation of China(No.52004187)。
文摘Microwave heating can rapidly and uniformly raise the temperature and accelerate the reaction rate.In this paper,microwave heating was used to improve the acid leaching,and the mechanism was investigated via microscopic morphology analysis and numerical simulation by COMSOL Multiphysics software.The effects of the microwave power,leaching temperature,CaF_(2) dosage,H_(2)SO_(4) concentration,and leaching time on the vanadium recovery were investigated.A vanadium recovery of 80.66%is obtained at a microwave power of 550 W,leaching temperature of 95℃,CaF_(2) dosage of 5wt%,H_(2)SO_(4) concentration of 20vol%,and leaching time of 2.5 h.Compared with conventional leaching technology,the vanadium recovery increases by 6.18%,and the leaching time shortens by 79.17%.More obvious pulverization of shale particles and delamination of mica minerals happen in the microwave-assisted leaching process.Numerical simulation results show that the temperature of vanadium shales increases with an increase in electric field(E-field).The distributions of E-field and temperature among vanadium shale particles are relatively uniform,except for the higher content at the contact position of the particles.The analysis results of scaleup experiments and leaching experiments indicate high-temperature hot spots in the process of microwave-assisted leaching,and the local high temperature destroys the mineral structure and accelerates the reaction rate.
基金Supported by Scientific and Technological Research and Development Planning Project of Hebei Province in2010(10457204D-14)~~
文摘After analysis of connotation of low-carbon scenic spots,the paper considered that a perfect low-carbon scenic spot is a comprehensive integrity with satisfying tourists' lowest tourist experience effect as the premise and with low energy consumption,low pollution and low emission as the foundation.Low-carbon tourist scenic spots had been classified into three types which are ecological type,cultural type and coupling type of ecology and culture.Representatives of each type of tourist scenic spot were illustrated.It proposed that government should play the leading role in cultivation of low-carbon scenic spot;tourism industry should enhance self supervision;tourism development mode should be transformed and upgrading of tourist products should be realized.By taking Yuntai Mountain Scenic Area of Henan Province for example,based on low-carbon tourist resources,low-carbon development of management,following measures realizing low-carbon economy were put forward:① purifying air quality and beautifying environment of scenic area;② sifting laggard productivity and protecting ecological resources in the scenic area by many means;③ sticking to low-carbon environmental protection concept and completing infrastructure service;④ developing tourist native products and souvenirs based on local resources;⑤ applying electronic access control ticket system,intelligent monitor system and LED information and communication platform,so as to achieve low-carbon management.
文摘By taking the twelve scenic spots in Ancient Lotus Pond Garden as study objects, they have been introduced and their names have been classified in accordance with allege and symbol nomenclature, linguistic rhetoric nomenclature, narration and description nomenclature, and emotion-endowing and ambition-expressing nomenclature adopted in related articles. Then, the cultural connotations of these scenic spots have been summarized, and Confucian thought and Taoist thought contained in "Surge Including Pavilion" and "High Principle Tower" have been analyzed. The research is aimed at enlightening modern garden workers through illustrating the connotation of the names of scenic spots, so that they can be inspired in the naming process.
文摘Cereal crops, including wheat, barley, oats, rye, etc., are the major sources of calories and proteins for most of the people in the world as well as in China. Cereal rusts and powdery mildews are very important diseases occurred on the cereal crops, which caused yield losses at 5-10% in general and even more than 30% while severe epidemics occurred. In recent years, with the global climate change, change of cultivation system and evolution of the pathogens, the world is facing great challenges caused by cereal diseases.
文摘The Chang-63 reservoir in the Huaqing area has widely developed tight sandstone ＂thick sand layers, but not reservoirs characterized by rich in oil＂, and it is thus necessary to further study its oil and gas enrichment law. This study builds porosity and fracture development and evolution models in different deposition environments, through core observation, casting thin section, SEM, porosity and permeability analysis, burial history analysis, and ＂four-property-relationships＂ analysis.
基金financial support from the National Natural Science Foundation of China(No.40201021)the Zhejiang Natural Science Foundation of China(M403040).
文摘In China, many scenic and tourism areas are suffering from the urbanization that results from physical development of tourism projects, leading to the removal of the vegetative cover, the creation of areas impermeable to water, in-stream modifications, and other problems. In this paper, the risk of soil erosion and its ecological risks in the West Lake Scenic Spots （WLSS） area were quantitatively evaluated by integrating the revised universal soil loss equation （RUSLE） with a digital elevation model （DEM） and geographical information system （GIS） software. The standard RUSLE factors were modified to account for local climatic and topographic characteristics reflected in the DEM maps, and for the soil types and vegetation cover types. An interface was created between the Areinfo software and RUSLE so that the level of soil erosion and its ecological risk in the WLSS area could be mapped immediately once the model factors were defined for the area. The results from an analysis using the Areinfo-RUSLE interface showed that the risk value in 93 % of the expanding western part of the WLSS area was moderate or more severe and the soil erosion risk in this area was thus large compared with that in the rest of the area. This paper mainly aimed to increase the awareness of the soil erosion risk in urbanizing areas and suggest that the local governments should consider the probable ecological risk resulting from soil erosion when enlarging and developing tourism areas.
基金Supported by the National Natural Science Foundation of China,No.82170525Beijing Shijitan Hospital Professionals Training Program,No.2023 LJRCDL.
文摘BACKGROUND Colorectal cancer(CRC)is the third most common cancer worldwide and the second leading cause of cancer-related death.Over the past two decades,numerous researchers have provided important evidence regarding the role of tight junction(TJ)proteins in the occurrence and progression of CRC.The causal relationship between the presence of specific TJ proteins and the development of CRC has also been confirmed.Despite the large number of publications in this field,a bibliometric study to review the current state of research and highlight the research trends and hotspots in this field has not yet been performed.AIM To analyze research on TJs and CRC,summarize the field’s history and current status,and predict future research directions.METHODS We searched the Science Citation Index Expanded database for all literature on CRC and TJs from 2001-2023.We used bibliometrics to analyze the data of these papers,such as the authors,countries,institutions,and references.Co-authorship,co-citation,and co-occurrence analyses were the main methods of analysis.CiteSpace and VOSviewer were used to visualize the results.RESULTS A total of 205 studies were ultimately identified.The number of publications on this topic has steadily increased since 2007.China and the United States have made the largest contributions to this field.Anticancer Research was the most prolific journal,publishing 8 articles,while the journal Oncogene had the highest average citation rate(68.33).Professor Dhawan P was the most prolific and cited author in this field.Co-occurrence analysis of keywords revealed that“tight junction protein expression”,“colorectal cancer”,“intestinal microbiota”,and“inflammatory bowel disease”had the highest frequency of occurrence,revealing the research hotspots and trends in this field.CONCLUSION This bibliometric analysis evaluated the scope and trends of TJ proteins in CRC,providing valuable research perspectives and future directions for studying the connection between the two.It is recommended to focus on emerging research hotspots,such as the correlations among intestinal microbiota,inflammatory bowel disease,TJ protein expression,and CRC.
文摘Petrographic comparison of andalusite in the contact aureole of the Fangshan pluton, Zhoukoudian, Beijing, China, and hornfels in the aureole of the Markfield diorite, Leicestershire, Eng- land, shows that spots characteristic of the outer zones of contact metamorphic aureoles did not form during the progressive stage of contact metamorphism, but are pseudomorphs after earlier andalusite with characteristic chiastolite microstructure. The baked margin produced by contact metamorphism of syenite against a dyke in the Houshihushan ring complex, Shanhaiguan, Hebei Province, China, is an unusual feature caused by the dyke＇s role as a feeder to a family of cone-sheets.
基金supported by the National Science and Technology Major Project(No.2016ZX05061)the Project of Sinopec Science&Technology Department(No.P18057-2).
文摘The shale gas accumulation conditions in the basin-margin transition zone of southeastern Chongqing in SW China are complex.In order to improve single-well productivity in this area,the geologic characteristics,major factors controlling the occurrence of sweet spots,and drilling/fracturing optimization were investigated in this study.The sweet spot evaluation system and criteria were established,and the horizontal-well-design technology was developed.The following three conclusions were drawn.First,the accumulation and high-productivity-oriented approaches for sweet spot evaluation are proposed and the criteria are established based on screened key indicators.Second,the horizontal well was designed based on:(1)the“six-map”method,to identify both the geology and engineering sweet spots for well locations;and(2)seismic attributes,to predict the development of fractures and cavities,and thus,avoid mud loss and improve the drilling efficiency.The target window,well-azimuth optimization,and the curvature were forecasted to improve the fracturing performances.Third,the Pingqiao anticline,Dongsheng anticline,Jinfo slope,and Wulong syncline were selected as Type I sweet spots.Currently,shale gas has been successfully discovered in the basin-margin transition zone and is being commercially developed.
基金funded by the National Natural Science Foundation of China(Nos.31772453 and 31970427 to WL,No.31672303 to CY and No.31770419 to HW)
文摘Background:Brood parasitic birds such as cuckoos(Cuculus spp.)can reduce their host’s reproductive success.Such selection pressure on the hosts has driven the evolution of defense behaviors such as egg rejection against cuckoo parasitism.Studies have shown that Cinereous Tits(Parus cinereus)in China have a good ability for recognizing foreign eggs.However,it is unclear whether egg spots play a role in egg recognition.The aims of our study were to investigate the egg recognition ability of two Cinereous Tit populations in China and to explore the role of spots in egg recognition.Methods:To test the effect of eggshell spots on egg recognition,pure white eggs of the White-rumped Munia(Lonchura striata)and eggs of White-rumped Munia painted with red brown spots were used to simulate experimental parasitism.Results:Egg experiments showed that Cinereous Tits rejected 51.5%of pure white eggs of the White-rumped Munia,but only 14.3%of spotted eggs of the White-rumped Munia.There was a significant difference in egg recognition and rejection rate between the two egg types.Conclusions:We conclude that eggshell spots on Cinereous Tit eggs had a signaling function and may be essential to tits for recognizing and rejecting parasitic eggs.
基金supported by the National Natural Science Foundation of China(Grant No.51965036).
文摘The cathode spots are a common phenomenon in the TIG(tungsten inert gas)welding process.However,it is rarely observed in the activating TIG welding process.This research is mainly focused on the effect of activating flux on cathode spots in the activating TIG welding.The characteristics and behaviors of cathode spots were investigated in activating TIG welding by the high-speed camera and the spectrograph.Three kinds of oxide(TiO_(2),SiO_(2),MnO_(2))and two halide(MnCl_(2),CaF_(2))activating fluxes are used in the activating TIG welding process.The results show that differ from the TIG welding,the oxide activating flux increases the number of cathode spots and decreases the velocity.The effect is the opposite for the halide activating flux.Moreover,the number of spots no longer varies with the current except TiO2 activating flux.As the temperature of the weld pool surface increases the spot moves away from the center.But this rule is not valid when silica and manganese compounds activating fluxes are used.The variation of cathode spots is caused by the oxide film reformed and the distribution of weld slag.The formation mechanism of cathode spots might be the impact of ions on the cathode surface and the strong electric field formed near the cathode surface.
