Since the beginning of the 21st century,major earthquakes have frequently occurred worldwide.To explore the impact of astronomical factors on earthquakes,in this study,the statistical analysis method of correlation is...Since the beginning of the 21st century,major earthquakes have frequently occurred worldwide.To explore the impact of astronomical factors on earthquakes,in this study,the statistical analysis method of correlation is used to systematically analyze the effects of astronomical factors,such as solar activity,Earth’s rotation,lunar declination angle,celestial tidal force,and other phenomena on M≥8 global earthquakes at the beginning of the 21st century.With regard to solar activity,this study focuses on the analysis of the 11-year and century cycles of solar activity.The causal relationship of the Earth’s rotation is not obvious in this work and previous works;in contrast,the valley period of the solar activity century cycle may be an important astronomical factor leading to the frequent occurrence of global earthquakes at the beginning of the 21st century.This topic warrants further study.展开更多
Micrometer-sized MoO2 hollow spheres were synthesized hydrothermally with ammonium heptamolybdate tetrahydrate as molybdenum source, Cetyltrimethylammonium bromide as structure-directing agent and C2H5OH as reducing a...Micrometer-sized MoO2 hollow spheres were synthesized hydrothermally with ammonium heptamolybdate tetrahydrate as molybdenum source, Cetyltrimethylammonium bromide as structure-directing agent and C2H5OH as reducing agent, respectively. The products were investigated by X-ray diffraction, thermo gravimetry and differential thermal analysis, scanning electron microscopy, transmission electron micraseopy and X-ray photoelectron spectroscopy. A morphology transition of "blocks-solid spheres-hollow spheres" during the growth procfess was observed and the possible mechanism for the formation of MoO2 samples was proposed to be through a microscale Kirkendall effcct.展开更多
To carry out the deep space exploration tasks near Sun-Earth Libration point L2, the CRTBP dynamic model was built up and the numerical conditional quasi-periodic orbit (Lissajons orbit) was computed near L2. Then, ...To carry out the deep space exploration tasks near Sun-Earth Libration point L2, the CRTBP dynamic model was built up and the numerical conditional quasi-periodic orbit (Lissajons orbit) was computed near L2. Then, a formation controller was designed with linear matrix inequality to overcome the difficuhy of parameter tuning. To meet the demands of formation accuracy and present thruster's capability, a threshold scheme was adopted for formation control. Finally, some numerical simulations and analysis were completed to demonstrate the feasibility of the proposed control strategy.展开更多
Black carbon (BC) aerosols can strongly absorb solar radiation in very broad spectral wavebands, from the visible to the infrared. As a potential factor contributing to global warming, BC aerosols not only directly ...Black carbon (BC) aerosols can strongly absorb solar radiation in very broad spectral wavebands, from the visible to the infrared. As a potential factor contributing to global warming, BC aerosols not only directly change the radiation balance of the earth-atmosphere system, but also indirectly affect global or regional climate by acting as cloud conden- sation nuclei or ice nuclei to alter cloud mierophysical properties. Here, recent progresses in the studies of radiative forcing due to BC and its climate effects are reviewed. The uncertainties in current researches are discussed and some suggestions are provided for future investigations.展开更多
The controversy between the IPCC and Non-governmental IPCC(NIPCC) on the attribution of global warming are reviewed.IPCC holds that today's global warming is mainly due to anthropogenic activities rather than natu...The controversy between the IPCC and Non-governmental IPCC(NIPCC) on the attribution of global warming are reviewed.IPCC holds that today's global warming is mainly due to anthropogenic activities rather than natural variability,which is emphasized by NIPCC.The surface temperature observations since the mid-20th century support the hypothesis of anthropogenic impact,but for the last one hundred years or so,natural forcings such as solar activity, volcanic eruptions and thermohaline circulation variations also have had great influences on the Earth's climate,especially on inter-decadal timescales.In addition,evidence suggests that the Medieval Warm Period(MWP) and Little Ice Age (LIA) are closely associated with the solar activity over the past 1 thousand years.Over the past 10 thousand years, the North Atlantic cold events and solar activity are closely correlated.Nevertheless,the physical mechanisms of the solar-climate variability and interrelation are not well understood,yet.Notably,a prevailing view recently indicates that galactic cosmic rays may result in climatic cooling through modulating global low cloud cover.However,its process and mechanism need to be further investigated.展开更多
Geoengineering (also called climate engineering), which refers to large-scale intervention in the Earth's climate system to counteract greenhouse gas-induced warming, has been one of the most rapidly growing areas ...Geoengineering (also called climate engineering), which refers to large-scale intervention in the Earth's climate system to counteract greenhouse gas-induced warming, has been one of the most rapidly growing areas of climate research as a potential option for tackling global warming. Here, we provide an overview of the scientific background and research progress of proposed geoengineering schemes. Geo- engineering can be broadly divided into two categories: solar geoengineering (also called solar radiation management, or SRM), which aims to reflect more sunlight to space, and carbon dioxide removal (CDR), which aims to reduce the CO2 content in the atmosphere. First, we review different proposed geoengineering methods involved in the solar radiation management and carbon dioxide removal schemes. Then, we discuss the fundamental science underlying the climate response to the carbon dioxide removal and solar radiation management schemes. We focus on two basic issues: 1) climate response to the reduction in solar irradiance and 2) climate response to the reduction in atmospheric COe. Next, we introduce an ongoing geoengineering research project in China that is supported by National Key Basic Research Program. This research project, being the first coordinated geoengineering research program in China, will systematically investigate the physical mechanisms, climate impacts, and risk and governance of a few targeted geoengineering schemes. It is expected that this research program will help us gain a deep understanding of the physical science underlying geoengineering schemes and the impacts of geoengineering on global climate, in particular, on the Asia monsoon region.展开更多
Solar radiation modification(SRM,also termed as geoengineering)has been proposed as a potential option to counteract anthropogenic warming.The underlying idea of SRM is to reduce the amount of sunlight reaching the at...Solar radiation modification(SRM,also termed as geoengineering)has been proposed as a potential option to counteract anthropogenic warming.The underlying idea of SRM is to reduce the amount of sunlight reaching the atmosphere and surface,thus offsetting some amount of global warming.Here,the authors use an Earth system model to investigate the impact of SRM on the global carbon cycle and ocean biogeochemistry.The authors simulate the temporal evolution of global climate and the carbon cycle from the pre-industrial period to the end of this century under three scenarios:the RCP4.5 CO_(2) emission pathway,the RCP8.5 CO_(2) emission pathway,and the RCP8.5 CO_(2) emission pathway with the implementation of SRM to maintain the global mean surface temperature at the level of RCP4.5.The simulations show that SRM,by altering global climate,also affects the global carbon cycle.Compared to the RCP8.5 simulation without SRM,by the year 2100,SRM reduces atmospheric CO_(2) by 65 ppm mainly as a result of increased CO_(2) uptake by the terrestrial biosphere.However,SRM-induced change in atmospheric CO_(2) and climate has a small effect in mitigating ocean acidification.By the year 2100,relative to RCP8.5,SRM causes a decrease in surface ocean hydrogen ion concentration([H^(+)])by 6% and attenuates the seasonal amplitude of[H^(+)]by about 10%.The simulations also show that SRM has a small effect on globally integrated ocean net primary productivity relative to the high-CO_(2) simulation without SRM.This study contributes to a comprehensive assessment of the effects of SRM on both the physical climate and the global carbon cycle.展开更多
The atmosphere protects humans, plants, ani- mals, and microorganisms from damaging doses of ultra- violet-B (UVB) solar radiation (280-320 nm) because it modifies the UVB reaching the Earth's surface. This modif...The atmosphere protects humans, plants, ani- mals, and microorganisms from damaging doses of ultra- violet-B (UVB) solar radiation (280-320 nm) because it modifies the UVB reaching the Earth's surface. This modification is a function of the solar radiation's path length through the atmosphere and the amount of each attenuator along the path length. The path length is deter- mined by solar zenith angle (SZA). The present work ex- plains the dependence of hemispherical transmittance of UVB on SZA. The database used consists of five years of hourly UVB and global solar radiation measurements. From 2001 to 2005, the South Valley University (SVU) meteorological research station (26.20°N, 32.75°E) car- ried out these measurements on a horizontal surface. In addition, the corresponding extraterrestrial UVB (UVBe^d and broadband solar radiation (Gext) were estimated. Consequently, the hemispherical transmittance of UVB (KtuvB) and the hemispherical transmittance of global solar radiation (Kt) were estimated. Furthermore, the UVB redaction due to the atmosphere was evaluated. An analy- sis of the dependence between KtuvB and SZA at different ranges of Kt was performed. A functional dependence between KtuvB and SZA (KtuvB=-a(SZA)+b) for very narrow Kt-ranges (width of ranges was 0.01) was devel- oped. The results are discussed, and the sensitivity of AKtuvB to △SZA for very narrow Kt-ranges was studied. It was found that the sensitivity of △KtUVB to ASZA slightly increases with increased Kt, which means KtuvB is sensi- tive to SZA as Kt increases. The maximum correlation (R) between KtuvB and SZA was equal to -0.83 for Kt= 0.76.展开更多
The preliminary purification and antimicrobial mechanism of antimicrobial peptide from Antarctic Krill were studied in this paper. The results showed that the molecular weight range of antimicrobial polypeptide (CMC...The preliminary purification and antimicrobial mechanism of antimicrobial peptide from Antarctic Krill were studied in this paper. The results showed that the molecular weight range of antimicrobial polypeptide (CMCC-1) obtained by cation exchange chromatography was between 245-709D as detected by molecular sieve chromatography, and the minimum inhibition concentration (MIC) of CMCC-1 against Staphylococcus aureus was 5.0mgmL^-1. The antimicrobial mechanism of CMCC-1 was studied with S. aureus as indicator bacterium. Compared with control group, the results of the experimental group in which S. aureus was treated with CMCC-1 were as follows: l) CMCC-1 could inhibit cell division at logarithmic phase. 2) The protein and reducing sugar con- tent, and the conductivity of culture medium increased, and the activity of alkaline phosphatase and [3-galactosidase could be detected in the culture medium. 3) Observation under scanning electron microscope revealed that somatic morphology became irregular, and then somatic surface became coarse. The cell became much smaller, and most somatic ceils gathered. The boundary between cells became dim and finally fused as a whole. 4) Observation under transmission electron microscope showed that the surface of S. aureus became rough and the reproducing ability was restrained. The cell wall became thin and the cytoplasm shrunk. Substances inside cell leaked out, which caused cells death. 5) SDS-PAGE analysis showed that some bands disappeared, and the residual bands became vague. 6) The genomic DNA electrophoresis results showed that the genomic DNA bands ofS. aureus were not degraded but the brightness significantly reduced. Thus, it is supposed that CMCC-1 could destroy the cell wall and membrane of S. aureu, increase the cell membrane permeability and the leaking-out of intracellular substances, and thus cause the death ofS. aureu.展开更多
Based on the results of multipurpose regional geochemical surveys of the Guizhou Province, geochemical characteristics of soil Se and Se-rich land resources in the central area of Guiyang City were studied and evaluat...Based on the results of multipurpose regional geochemical surveys of the Guizhou Province, geochemical characteristics of soil Se and Se-rich land resources in the central area of Guiyang City were studied and evaluated.Major conclusions are as follows:(1) the Se content in surface soil of the central area of Guiyang City was 0.17–2.89 mg kg^(-1), and the average was 0.78 mg kg^(-1), which were respectively 2.6 and 3.9 times of the national background value of soil and the world background value of soil.The Se content in deep soil was 0.11–1.48 mg kg^(-1), and the average was 0.44 mg kg^(-1), which were respectively 1.5 and2.2 times of the national background value of soil and the world background value of soil. The soil Se content decreased with the increase in the soil depth on the vertical profile, and the surface soil had a higher Se content.(2)Distribution of Se content was mainly affected by parent material, physicochemical properties of soil and other components, soil type, and land use type. Parent material played a key role, as the soil Se content was mainly originated from parent rock and increased with the background value of Se in parent rock, physicochemical properties of soil and other components had certain influences upon the Se content. Se was shown to have a significant linear positive correlation with S and organic carbon but no significant correlation with p H value. Se content varied with different types of soil as follows: skeleton soil > yellow soil > paddy soil > limestone soil > purple soil. Land use type also hadcertain influences upon the soil Se content as follows: dry land > construction land > garden plot > grassland =garden plot > forest land.(3) Taking 0.4 mg kg^(-1)B x(Se) <3.0 mg kg^(-1) as the standard for Se-rich soil, Se-rich soil of the study area covered an area of 2224 km^2 and 92.5% of the total area; the remaining is general soil. The study area had no Se-excess soil. Therefore, the central area of Guiyang City has a high proportion of Se-rich land, a large area of Serich land resources, and a moderate selenium enrichment strength, which have been rarely seen anywhere and provide advantageous resources for the development of Se-rich featured agriculture.展开更多
Anatase Ti0_(2) nanosheet-based hierarchical spheres(HSs)with nearly 100%exposed{001}facets were synthesized via a facile solvothermal process.Using these hierarchical spheres as a scattering layer on nanocrystaline T...Anatase Ti0_(2) nanosheet-based hierarchical spheres(HSs)with nearly 100%exposed{001}facets were synthesized via a facile solvothermal process.Using these hierarchical spheres as a scattering layer on nanocrystaline TiO_(2)film,hi-layered dye-sensitized solar cells(DSSCs)have been fabricated by electrophoresis deposition method,which well preserved the fragile hierarchical structure.Owing to the superior dye adsorption and light scattering effect of HSs,an overall energy conversion efficiency of 7.38%is achieved,which is 26%higher than that of nanoparticle-based photoanode.展开更多
Investigation of new orbit geometries exhibits a very attractive behavior for a spacecraft to monitor space weather coming from the Sun. Several orbit transfer mechanisms are analyzed as potential alternatives to moni...Investigation of new orbit geometries exhibits a very attractive behavior for a spacecraft to monitor space weather coming from the Sun. Several orbit transfer mechanisms are analyzed as potential alternatives to monitor solar activity such as a sub-solar orbit or quasi-satellite orbit and short and long heteroclinic and homoclinic connections between the triangular points L4 and L5 and the collinear point L3 of the CRTBP (circular restricted three-body problem) in the Sun-Earth system. These trajectories could serve as channels through where material can be transported from L5 to L3 by performing small maneuvers at the departure of the Trojan orbit. The size of these maneuvers at L5 is between 299 m/s and 730 m/s depending on the transfer time of the trajectory and does not need any deterministic maneuvers at L3. Our results suggest that material may also be transported from the Trojan orbits to quasi-satellite orbits or even displaced quasi-satellite orbits.展开更多
Simple GNSS navigation receivers, developed for the mass market, can be used for positioning with sub centimeter accuracy in a wireless sensor network if the read-out of the carrier phase data is possible and all data...Simple GNSS navigation receivers, developed for the mass market, can be used for positioning with sub centimeter accuracy in a wireless sensor network if the read-out of the carrier phase data is possible and all data is permanently broadcast to a central computer for near real time processing of the respective base lines. Experiences gained in two research projects related to landslide monitoring are depicted in terms of quality and reliability of the results by the developed approach. As far as possible a modular system set up with commercial off-the-shelf components, e.g., standard WLAN fur commtmication, solar batteries with solar panels for autarkic power supply and in cooperation of existing proofed program tools is chosen. The challenge of the still ongoing development is to have a flexible and robust GNSS based sensor network available - concerned not only for landslide monitoring in future.展开更多
To realize the automatic detection of solar radio burst(SRB)intensity,detection based on a modified multifactor support vector machine(SVM)algorithm is proposed.First,the influence of SRB on global navigation satellit...To realize the automatic detection of solar radio burst(SRB)intensity,detection based on a modified multifactor support vector machine(SVM)algorithm is proposed.First,the influence of SRB on global navigation satellite system(GNSS)signals is analyzed.Feature vectors,which can reflect the SRB intensity of stations,are also extracted.SRB intensity is classified according to the solar radio flux,and different class labels correspond to different SRB intensity types.The training samples are composed of feature vectors and their corresponding class labels.Second,training samples are input into SVM classifiers to one-against-one training to obtain the optimal classification models.Finally,the optimal classification model is synthesized into a modified multifactor SVM classifier,which is used to automatically detect the SRB intensity of new data.Experimental results indicate that for historical SRB events,the average accuracy of SRB intensity detection is greater than 90%when the solar incident angle is higher than 20°.Compared with other methods,the proposed method considers many factors with higher accuracy and does not rely on radio telescopes,thereby saving cost.展开更多
Atmospheric carbon dioxide concentration [CO2],incoming solar radiation and sea ice coverage are among the most important factors that control the global climate.By applying the simple cell-to-cell mapping technique t...Atmospheric carbon dioxide concentration [CO2],incoming solar radiation and sea ice coverage are among the most important factors that control the global climate.By applying the simple cell-to-cell mapping technique to a simplified atmosphere-ocean-sea ice feedback climate model,effects of these factors on the stability of the climatic system are studied.The current climatic system is found to be stable but highly nonlinear.The resiliency of stability increases with [CO2] to a summit when [CO2] reaches 290 μL/L which is comparable to the pre-industrial level,suggesting carbon dioxide is essential to the stability of the global climate.With [CO2] rising further,the global climate stability decreases,the mean ocean temperature goes up and the sea ice coverage shrinks in the polar region.When the incoming solar radiation is intensified,the ice coverage gradually diminishes,but the mean ocean temperature remains relatively constant.Overall,our analysis suggests that at the current levels of three external factors the stability of global climate is highly resilient.However,there exists a possibility of extreme states of climate,such as a snow-ball earth and an ice-free earth.展开更多
Having found some orbit variation mechanisms of natural satellites and planets, the author has revealed the formation and evolution law of the Moon. According to this law, the author has further revealed the formation...Having found some orbit variation mechanisms of natural satellites and planets, the author has revealed the formation and evolution law of the Moon. According to this law, the author has further revealed the formation and evolution law of the Solar System and other galaxies in the universe. Especially, the author has also explained why the eight planets around the Sun are prograde planets, why the orbits of the eight planets almost lie in the same plane, and why most planets rotate around their own axes from west to east. Additionally, the author could also explain the expansion of the universe as well as the cause of global climate change.展开更多
文摘Since the beginning of the 21st century,major earthquakes have frequently occurred worldwide.To explore the impact of astronomical factors on earthquakes,in this study,the statistical analysis method of correlation is used to systematically analyze the effects of astronomical factors,such as solar activity,Earth’s rotation,lunar declination angle,celestial tidal force,and other phenomena on M≥8 global earthquakes at the beginning of the 21st century.With regard to solar activity,this study focuses on the analysis of the 11-year and century cycles of solar activity.The causal relationship of the Earth’s rotation is not obvious in this work and previous works;in contrast,the valley period of the solar activity century cycle may be an important astronomical factor leading to the frequent occurrence of global earthquakes at the beginning of the 21st century.This topic warrants further study.
文摘Micrometer-sized MoO2 hollow spheres were synthesized hydrothermally with ammonium heptamolybdate tetrahydrate as molybdenum source, Cetyltrimethylammonium bromide as structure-directing agent and C2H5OH as reducing agent, respectively. The products were investigated by X-ray diffraction, thermo gravimetry and differential thermal analysis, scanning electron microscopy, transmission electron micraseopy and X-ray photoelectron spectroscopy. A morphology transition of "blocks-solid spheres-hollow spheres" during the growth procfess was observed and the possible mechanism for the formation of MoO2 samples was proposed to be through a microscale Kirkendall effcct.
文摘To carry out the deep space exploration tasks near Sun-Earth Libration point L2, the CRTBP dynamic model was built up and the numerical conditional quasi-periodic orbit (Lissajons orbit) was computed near L2. Then, a formation controller was designed with linear matrix inequality to overcome the difficuhy of parameter tuning. To meet the demands of formation accuracy and present thruster's capability, a threshold scheme was adopted for formation control. Finally, some numerical simulations and analysis were completed to demonstrate the feasibility of the proposed control strategy.
基金financially supported by the National Basic Research Program of China(2011CB403405 and 2010CB955608)the Public Meteorology Special Foundation of MOST(GYHY200906020)
文摘Black carbon (BC) aerosols can strongly absorb solar radiation in very broad spectral wavebands, from the visible to the infrared. As a potential factor contributing to global warming, BC aerosols not only directly change the radiation balance of the earth-atmosphere system, but also indirectly affect global or regional climate by acting as cloud conden- sation nuclei or ice nuclei to alter cloud mierophysical properties. Here, recent progresses in the studies of radiative forcing due to BC and its climate effects are reviewed. The uncertainties in current researches are discussed and some suggestions are provided for future investigations.
基金supported by National Basic Research Program of China(No.2010CB950104)
文摘The controversy between the IPCC and Non-governmental IPCC(NIPCC) on the attribution of global warming are reviewed.IPCC holds that today's global warming is mainly due to anthropogenic activities rather than natural variability,which is emphasized by NIPCC.The surface temperature observations since the mid-20th century support the hypothesis of anthropogenic impact,but for the last one hundred years or so,natural forcings such as solar activity, volcanic eruptions and thermohaline circulation variations also have had great influences on the Earth's climate,especially on inter-decadal timescales.In addition,evidence suggests that the Medieval Warm Period(MWP) and Little Ice Age (LIA) are closely associated with the solar activity over the past 1 thousand years.Over the past 10 thousand years, the North Atlantic cold events and solar activity are closely correlated.Nevertheless,the physical mechanisms of the solar-climate variability and interrelation are not well understood,yet.Notably,a prevailing view recently indicates that galactic cosmic rays may result in climatic cooling through modulating global low cloud cover.However,its process and mechanism need to be further investigated.
基金supported by National Key Basic Research Program of China (2015CB953601)National Natural Science Foundation of China (41422503, 41276073)+1 种基金the Fundamental Research Funds for the Central Universities (2015XZZX00405)Zhejiang University K. P. Chao's High Technology Development Foundation
文摘Geoengineering (also called climate engineering), which refers to large-scale intervention in the Earth's climate system to counteract greenhouse gas-induced warming, has been one of the most rapidly growing areas of climate research as a potential option for tackling global warming. Here, we provide an overview of the scientific background and research progress of proposed geoengineering schemes. Geo- engineering can be broadly divided into two categories: solar geoengineering (also called solar radiation management, or SRM), which aims to reflect more sunlight to space, and carbon dioxide removal (CDR), which aims to reduce the CO2 content in the atmosphere. First, we review different proposed geoengineering methods involved in the solar radiation management and carbon dioxide removal schemes. Then, we discuss the fundamental science underlying the climate response to the carbon dioxide removal and solar radiation management schemes. We focus on two basic issues: 1) climate response to the reduction in solar irradiance and 2) climate response to the reduction in atmospheric COe. Next, we introduce an ongoing geoengineering research project in China that is supported by National Key Basic Research Program. This research project, being the first coordinated geoengineering research program in China, will systematically investigate the physical mechanisms, climate impacts, and risk and governance of a few targeted geoengineering schemes. It is expected that this research program will help us gain a deep understanding of the physical science underlying geoengineering schemes and the impacts of geoengineering on global climate, in particular, on the Asia monsoon region.
基金supported by the National Natural Science Foundation of China[grant number 41975103].
文摘Solar radiation modification(SRM,also termed as geoengineering)has been proposed as a potential option to counteract anthropogenic warming.The underlying idea of SRM is to reduce the amount of sunlight reaching the atmosphere and surface,thus offsetting some amount of global warming.Here,the authors use an Earth system model to investigate the impact of SRM on the global carbon cycle and ocean biogeochemistry.The authors simulate the temporal evolution of global climate and the carbon cycle from the pre-industrial period to the end of this century under three scenarios:the RCP4.5 CO_(2) emission pathway,the RCP8.5 CO_(2) emission pathway,and the RCP8.5 CO_(2) emission pathway with the implementation of SRM to maintain the global mean surface temperature at the level of RCP4.5.The simulations show that SRM,by altering global climate,also affects the global carbon cycle.Compared to the RCP8.5 simulation without SRM,by the year 2100,SRM reduces atmospheric CO_(2) by 65 ppm mainly as a result of increased CO_(2) uptake by the terrestrial biosphere.However,SRM-induced change in atmospheric CO_(2) and climate has a small effect in mitigating ocean acidification.By the year 2100,relative to RCP8.5,SRM causes a decrease in surface ocean hydrogen ion concentration([H^(+)])by 6% and attenuates the seasonal amplitude of[H^(+)]by about 10%.The simulations also show that SRM has a small effect on globally integrated ocean net primary productivity relative to the high-CO_(2) simulation without SRM.This study contributes to a comprehensive assessment of the effects of SRM on both the physical climate and the global carbon cycle.
基金supported by the Deanship of Scientific Research from King Saud University
文摘The atmosphere protects humans, plants, ani- mals, and microorganisms from damaging doses of ultra- violet-B (UVB) solar radiation (280-320 nm) because it modifies the UVB reaching the Earth's surface. This modification is a function of the solar radiation's path length through the atmosphere and the amount of each attenuator along the path length. The path length is deter- mined by solar zenith angle (SZA). The present work ex- plains the dependence of hemispherical transmittance of UVB on SZA. The database used consists of five years of hourly UVB and global solar radiation measurements. From 2001 to 2005, the South Valley University (SVU) meteorological research station (26.20°N, 32.75°E) car- ried out these measurements on a horizontal surface. In addition, the corresponding extraterrestrial UVB (UVBe^d and broadband solar radiation (Gext) were estimated. Consequently, the hemispherical transmittance of UVB (KtuvB) and the hemispherical transmittance of global solar radiation (Kt) were estimated. Furthermore, the UVB redaction due to the atmosphere was evaluated. An analy- sis of the dependence between KtuvB and SZA at different ranges of Kt was performed. A functional dependence between KtuvB and SZA (KtuvB=-a(SZA)+b) for very narrow Kt-ranges (width of ranges was 0.01) was devel- oped. The results are discussed, and the sensitivity of AKtuvB to △SZA for very narrow Kt-ranges was studied. It was found that the sensitivity of △KtUVB to ASZA slightly increases with increased Kt, which means KtuvB is sensi- tive to SZA as Kt increases. The maximum correlation (R) between KtuvB and SZA was equal to -0.83 for Kt= 0.76.
基金supported by the National Science and Technology Pillar Program(2013BAD13B03)National Natural Science Foundation of China(Grant 31201311)Special Scientific Research Funds for Central Non-profit Institutes,Yellow Sea Fisheries Research Institute(20603022012001)
文摘The preliminary purification and antimicrobial mechanism of antimicrobial peptide from Antarctic Krill were studied in this paper. The results showed that the molecular weight range of antimicrobial polypeptide (CMCC-1) obtained by cation exchange chromatography was between 245-709D as detected by molecular sieve chromatography, and the minimum inhibition concentration (MIC) of CMCC-1 against Staphylococcus aureus was 5.0mgmL^-1. The antimicrobial mechanism of CMCC-1 was studied with S. aureus as indicator bacterium. Compared with control group, the results of the experimental group in which S. aureus was treated with CMCC-1 were as follows: l) CMCC-1 could inhibit cell division at logarithmic phase. 2) The protein and reducing sugar con- tent, and the conductivity of culture medium increased, and the activity of alkaline phosphatase and [3-galactosidase could be detected in the culture medium. 3) Observation under scanning electron microscope revealed that somatic morphology became irregular, and then somatic surface became coarse. The cell became much smaller, and most somatic ceils gathered. The boundary between cells became dim and finally fused as a whole. 4) Observation under transmission electron microscope showed that the surface of S. aureus became rough and the reproducing ability was restrained. The cell wall became thin and the cytoplasm shrunk. Substances inside cell leaked out, which caused cells death. 5) SDS-PAGE analysis showed that some bands disappeared, and the residual bands became vague. 6) The genomic DNA electrophoresis results showed that the genomic DNA bands ofS. aureus were not degraded but the brightness significantly reduced. Thus, it is supposed that CMCC-1 could destroy the cell wall and membrane of S. aureu, increase the cell membrane permeability and the leaking-out of intracellular substances, and thus cause the death ofS. aureu.
基金supported by outstanding science and technology education personnel special funds of Guizhou Province (Specific words in Guizhou Province (2012)No.27)National multipurpose regional geochemical survey Project (GZTR20070110)
文摘Based on the results of multipurpose regional geochemical surveys of the Guizhou Province, geochemical characteristics of soil Se and Se-rich land resources in the central area of Guiyang City were studied and evaluated.Major conclusions are as follows:(1) the Se content in surface soil of the central area of Guiyang City was 0.17–2.89 mg kg^(-1), and the average was 0.78 mg kg^(-1), which were respectively 2.6 and 3.9 times of the national background value of soil and the world background value of soil.The Se content in deep soil was 0.11–1.48 mg kg^(-1), and the average was 0.44 mg kg^(-1), which were respectively 1.5 and2.2 times of the national background value of soil and the world background value of soil. The soil Se content decreased with the increase in the soil depth on the vertical profile, and the surface soil had a higher Se content.(2)Distribution of Se content was mainly affected by parent material, physicochemical properties of soil and other components, soil type, and land use type. Parent material played a key role, as the soil Se content was mainly originated from parent rock and increased with the background value of Se in parent rock, physicochemical properties of soil and other components had certain influences upon the Se content. Se was shown to have a significant linear positive correlation with S and organic carbon but no significant correlation with p H value. Se content varied with different types of soil as follows: skeleton soil > yellow soil > paddy soil > limestone soil > purple soil. Land use type also hadcertain influences upon the soil Se content as follows: dry land > construction land > garden plot > grassland =garden plot > forest land.(3) Taking 0.4 mg kg^(-1)B x(Se) <3.0 mg kg^(-1) as the standard for Se-rich soil, Se-rich soil of the study area covered an area of 2224 km^2 and 92.5% of the total area; the remaining is general soil. The study area had no Se-excess soil. Therefore, the central area of Guiyang City has a high proportion of Se-rich land, a large area of Serich land resources, and a moderate selenium enrichment strength, which have been rarely seen anywhere and provide advantageous resources for the development of Se-rich featured agriculture.
文摘Anatase Ti0_(2) nanosheet-based hierarchical spheres(HSs)with nearly 100%exposed{001}facets were synthesized via a facile solvothermal process.Using these hierarchical spheres as a scattering layer on nanocrystaline TiO_(2)film,hi-layered dye-sensitized solar cells(DSSCs)have been fabricated by electrophoresis deposition method,which well preserved the fragile hierarchical structure.Owing to the superior dye adsorption and light scattering effect of HSs,an overall energy conversion efficiency of 7.38%is achieved,which is 26%higher than that of nanoparticle-based photoanode.
文摘Investigation of new orbit geometries exhibits a very attractive behavior for a spacecraft to monitor space weather coming from the Sun. Several orbit transfer mechanisms are analyzed as potential alternatives to monitor solar activity such as a sub-solar orbit or quasi-satellite orbit and short and long heteroclinic and homoclinic connections between the triangular points L4 and L5 and the collinear point L3 of the CRTBP (circular restricted three-body problem) in the Sun-Earth system. These trajectories could serve as channels through where material can be transported from L5 to L3 by performing small maneuvers at the departure of the Trojan orbit. The size of these maneuvers at L5 is between 299 m/s and 730 m/s depending on the transfer time of the trajectory and does not need any deterministic maneuvers at L3. Our results suggest that material may also be transported from the Trojan orbits to quasi-satellite orbits or even displaced quasi-satellite orbits.
文摘Simple GNSS navigation receivers, developed for the mass market, can be used for positioning with sub centimeter accuracy in a wireless sensor network if the read-out of the carrier phase data is possible and all data is permanently broadcast to a central computer for near real time processing of the respective base lines. Experiences gained in two research projects related to landslide monitoring are depicted in terms of quality and reliability of the results by the developed approach. As far as possible a modular system set up with commercial off-the-shelf components, e.g., standard WLAN fur commtmication, solar batteries with solar panels for autarkic power supply and in cooperation of existing proofed program tools is chosen. The challenge of the still ongoing development is to have a flexible and robust GNSS based sensor network available - concerned not only for landslide monitoring in future.
基金The National Key Research and Development Plan of China(No.2018YFB0505103)the National Natural Science Foundation of China(No.61873064)。
文摘To realize the automatic detection of solar radio burst(SRB)intensity,detection based on a modified multifactor support vector machine(SVM)algorithm is proposed.First,the influence of SRB on global navigation satellite system(GNSS)signals is analyzed.Feature vectors,which can reflect the SRB intensity of stations,are also extracted.SRB intensity is classified according to the solar radio flux,and different class labels correspond to different SRB intensity types.The training samples are composed of feature vectors and their corresponding class labels.Second,training samples are input into SVM classifiers to one-against-one training to obtain the optimal classification models.Finally,the optimal classification model is synthesized into a modified multifactor SVM classifier,which is used to automatically detect the SRB intensity of new data.Experimental results indicate that for historical SRB events,the average accuracy of SRB intensity detection is greater than 90%when the solar incident angle is higher than 20°.Compared with other methods,the proposed method considers many factors with higher accuracy and does not rely on radio telescopes,thereby saving cost.
基金Funded by the National Natural Science Foundation of China(No.20877105)
文摘Atmospheric carbon dioxide concentration [CO2],incoming solar radiation and sea ice coverage are among the most important factors that control the global climate.By applying the simple cell-to-cell mapping technique to a simplified atmosphere-ocean-sea ice feedback climate model,effects of these factors on the stability of the climatic system are studied.The current climatic system is found to be stable but highly nonlinear.The resiliency of stability increases with [CO2] to a summit when [CO2] reaches 290 μL/L which is comparable to the pre-industrial level,suggesting carbon dioxide is essential to the stability of the global climate.With [CO2] rising further,the global climate stability decreases,the mean ocean temperature goes up and the sea ice coverage shrinks in the polar region.When the incoming solar radiation is intensified,the ice coverage gradually diminishes,but the mean ocean temperature remains relatively constant.Overall,our analysis suggests that at the current levels of three external factors the stability of global climate is highly resilient.However,there exists a possibility of extreme states of climate,such as a snow-ball earth and an ice-free earth.
文摘Having found some orbit variation mechanisms of natural satellites and planets, the author has revealed the formation and evolution law of the Moon. According to this law, the author has further revealed the formation and evolution law of the Solar System and other galaxies in the universe. Especially, the author has also explained why the eight planets around the Sun are prograde planets, why the orbits of the eight planets almost lie in the same plane, and why most planets rotate around their own axes from west to east. Additionally, the author could also explain the expansion of the universe as well as the cause of global climate change.