Here we report our recent magnetic fabric investigation of loess deposition in Shagou section, located at the northeastern Qilian Mountains, the northeastern rim of the Tibetan Plateau. On the basis of environmental m...Here we report our recent magnetic fabric investigation of loess deposition in Shagou section, located at the northeastern Qilian Mountains, the northeastern rim of the Tibetan Plateau. On the basis of environmental magnetism data, we indicate that the variation of anisotropy of magnetic susceptibility (AMS) parameters, especially the foliation (F) and degree of anisotropy (P), might be more sensitive to the environmental change in the arid and semiarid regions than the magnetic susceptibility fluctuation. During the investigated interval, from 0.83 to 0.128 Ma, most of the middle to late Pleistocene significant climate change can be unraveled by the AMS parameters, such as the strengthening of cold/dry climate, the step drying event occurred nearly 250 ka, and the severe environmental change in MIS16. Our results also suggest that there is strong correlation between median diameter (Md) of grain size, F, and P. We propose that the AMS parameters can act as an important paleoenvironmental change indicator in the arid and semiarid regions.展开更多
A new kind of phenyl-functionalized magnetic fibrous mesoporous silica(Fe3 O4@Si O2@KCC-1-phenyl) was prepared by copolymerization as an efficient adsorbent for the magnetic extraction of phthalate esters from environ...A new kind of phenyl-functionalized magnetic fibrous mesoporous silica(Fe3 O4@Si O2@KCC-1-phenyl) was prepared by copolymerization as an efficient adsorbent for the magnetic extraction of phthalate esters from environmental water samples. The obtained Fe3 O4@Si O2@KCC-1-phenyl showed monodisperse fibrous spherical morphology, fairly strong magnetic response(29 emu/g), and an abundant π-electron system, which allowed rapid isolation of the Fe3 O4@Si O2@KCC-1-phenyl from solutions upon applying an appropriate magnetic field. Several variables that affect the extraction efficiency of the analytes,including the type of the elution solvent, amount of adsorbent, extraction time and reusability, were investigated and optimized. Under optimum conditions, the Fe3 O4@Si O2@KCC-1-phenyl was used for the extraction of four phthalate esters from environmental water samples followed by high-performance liquid chromatographic analysis. Validation experiments indicated that the developed method presented good linearity(0.1-20 ng/m L), low limit of detection(7.5-29 μg/L, S/N =3). The proposed method was applied to the determination of phthalate esters in different real water samples, with relative recoveries of 93%-103.4%and relative standard deviation of 0.8%-8.3%.展开更多
In this paper, authors report some results obtained from systematic rock magnetic measurements on Core NP95 1 and Core NG93 1 , which were collected from the Prydz Bay, Eastern Antarctica and Great Wall Bay (Maxwell...In this paper, authors report some results obtained from systematic rock magnetic measurements on Core NP95 1 and Core NG93 1 , which were collected from the Prydz Bay, Eastern Antarctica and Great Wall Bay (Maxwell Bay), Western Antarctica respectively during the 11th and 9th CHINARE and a sequence of paleoclimate variations is well established based on sediment rock magnetic properties. In Antarctica, the magnetic properties show a close linkage to paleoenvironmental variations. The Core NP95 1 well recorded several paleoclimatic events, such as Heinrich event 1, Bolling Allerod warm period and Younger Dryas cold event. The Heinrich event 1 occurred at about 14 2 ka B.P., Younger Dryas cold event occurred between 11 7 ka B.P. and 10 3 ka B.P., and the boundary of Pleistocene and Holocene in Antarctica is 10 3 ka B.P.. In Holocene, two warm periods were recorded at about 10 0 ka B.P. and 6 0 ka B.P. with a little cold period between them. After 6 0 ka B.P. , two cores both recorded a cold climatic oscillation. Paleoclimate described by two cores rock magnetic measurements was simultaneously changed in Eastern and Western Antarctica during the same period two cores commonly covered.展开更多
Mn-doped ZnO nanocrystals are synthesized by a wet chemical route and treated in H2/Ar atmosphere with different H2/Ar ratios. It is found that hydrogen annealing could change the coordination environment of Mn in ZnO...Mn-doped ZnO nanocrystals are synthesized by a wet chemical route and treated in H2/Ar atmosphere with different H2/Ar ratios. It is found that hydrogen annealing could change the coordination environment of Mn in ZnO lattice and manipulate the magnetic properties of Mn-doped ZnO. Mn ions initially enter into interstitial sites and a Mn3＋ 06 octahedral coordination is produced in the prepared Mn-doped ZnO sample, in which the nearest neighbor Mn3＋ and 02 ions could form a Mn3＋-O2--Mn3＋ complex. After H2 annealing, interstitial Mn ions can substitute for Zn to generate the Mn2＋O4 tetrahedral coordination in the nanocrystals, in which neighboring Mn2＋ ions and H atoms could form a Mn2＋-O2--Mn2＋ complex and Mn-H-Mn bridge structure. The magnetic measurement of the as-prepared sample shows room temperature paramagnetic behavior due to the Mn3＋-O2--Mn3＋ complex, while the annealed samples exhibit their ferromagnetism, which originates from the Mn-H-Mn bridge structure and the Mn-Mn exchange interaction in the Mn2＋-O2--Mn2＋ complex.展开更多
To differentiate between natural and anthropogenic particulate sources in the atmosphere in Lanzhou City, samples were collected in different sites. The dust flux was calculated and magnetic measurements were conducte...To differentiate between natural and anthropogenic particulate sources in the atmosphere in Lanzhou City, samples were collected in different sites. The dust flux was calculated and magnetic measurements were conducted. Results show a distinct pattern of variation of dust flux within a year and it agrees with the shifts of atmospheric circulation regime. The magnetic parameters indicate that natural sources are the major components of atmospheric particulate during late spring and early summer, while anthropogenic sources contribute much more during winter months. The data also support the earlier findings that magnetic parameters are effective for differentiating between particulate arising from natural sources such as soil erosion and from anthropogenic sources such as coal combustion.展开更多
This study presents a statistical landslide susceptibility assessment(LSA) in a dynamic environment. The study area is located in the eastern part of Lanzhou, NW China. The Lanzhou area has exhibited rapid urbanizatio...This study presents a statistical landslide susceptibility assessment(LSA) in a dynamic environment. The study area is located in the eastern part of Lanzhou, NW China. The Lanzhou area has exhibited rapid urbanization rates over the past decade associated with greening, continuous land use change, and geomorphic reshaping activities. To consider the dynamics of the environment in the LSA, multitemporal data for landslide inventories and the corresponding causal factors were collected. The weights of evidence(Wof E) method was used to perform the LSA. Three time stamps, i.e., 2000, 2012, and 2016, were selected to assess the state of landslide susceptibility over time. The results show a clear evolution of the landslide susceptibility patterns that was mainly governed by anthropogenic activities directed toward generating safer building grounds for civil infrastructure. The low and very low susceptibility areas increased by approximately 10% between 2000 and 2016. At the same time, areas of medium, high and very high susceptibility zones decreased proportionally. Based on the results, an approach to design the statistical LSA under dynamic conditions is proposed, the issues and limitations of this approach are also discussed. The study shows that under dynamic conditions, the requirements for data quantity and quality increase significantly. A dynamic environment requires greater effort to estimate the causal relations between the landslides and controlling factors as well as for model validation.展开更多
In the 1990s,the American Nurses Association established a certification program called the Magnet Recognition Program through the American Nurses Credentialing Centre(ANCC)to complement the quality care provided to p...In the 1990s,the American Nurses Association established a certification program called the Magnet Recognition Program through the American Nurses Credentialing Centre(ANCC)to complement the quality care provided to patients by hospitals.After the program was recognised,hospitals were identified as magnet hospitals[1].Some studies show that magnet hospitals provide a healthier working environment for nurses,accompanied by higher nurse satisfaction and better patient prognosis than non-magnet hospitals[2e5].The nursing work environment is the sum of various elements that directly or indirectly affect the patient care system[6].Improving the nursing work environment is a focal point and challenge for nursing administrators.Therefore,administrators in magnet hospitals usually apply a variety of assessment tools for effective evaluation of the nursing work environment to maintain and improve the health of the environment.展开更多
On the basis of measuring the magnetic parameters of sediment in Core YDZ1, combined with a grain size analysis and Carbon-14 dating, the magnetic properties of sediment and sedimentary environment in the Huanghe（Yel...On the basis of measuring the magnetic parameters of sediment in Core YDZ1, combined with a grain size analysis and Carbon-14 dating, the magnetic properties of sediment and sedimentary environment in the Huanghe（Yellow River） Delta area after the last glacial maximum have been studied. The results show that the ferrimagnetic minerals of a pseudo single domain and multi domain particles dominate the magnetic properties of sediment in Core YDZ1. The imperfect anti ferrimagnetic minerals have more contribution on sediment in a depth of 24.0–22.1 m, and more stable-single domain and pseudo single domain particles exist. The susceptibility of anhysteretic remanent magnetization and the ratio of the susceptibility of anhysteretic remanent magnetization to saturation isothermal remanent magnetization show a decrease trend below depth of 24 m, a marked increase trend in a depth of 24.0–13.5 m, and a rapid decrease at depth of 13.5 m, then a fluctuation trend upward. The above two magnetic parameters and the ratio of the susceptibility of anhysteretic remanent magnetization to the mass susceptibility can be regarded as the proxy indicators for the content of clay（〈4 μm）and the fine-grained size（〈32 μm）. The sedimentary environment after the last glacial maximum in the Huanghe Delta area has experienced the fluvial facies, the tidal flat facies, the neritic facies, the pro delta facies, the delta front facies and the floodplain facies. Thickness of the Holocene transgression layer is 10.5 m and the depth of substrate is about 24 m according to the YDZ1 core. The sedimentary dynamic has a variation trend with strongweak-strong, which has been proved by the Flemming triangular schema.展开更多
The Holocene environmental evolution in coastal area, including deltas and estuaries, is vital to the Neolithic colonization in the eastern China. A 29-m long sediment core XL was obtained from the region between the ...The Holocene environmental evolution in coastal area, including deltas and estuaries, is vital to the Neolithic colonization in the eastern China. A 29-m long sediment core XL was obtained from the region between the Taihu Lake and Qiantang Estuary, and multiple analyses on the core sediments have been done to investigate the evolution history of the inner coastal zone of Hangzhou Bay during the Holocene. Six sedimentary facies are identified since the late Pleistocene, including the paleosol at the bottom, overlain by tidal-flat-channel complex(TFC), tidal-distributary-channel(TDC), inner estuarine basin(IEB), subtidal-to-intertidal-flat, and fluvial-plain facies. The TFC and TDC facies are dated to be formed before 8500 cal yr BP, featured by relatively coarse sediments, high magnetic properties and less abundant foraminifera, denoting the tide-influenced setting with large terrestrial inputs. The IEB facies characterized by the most abundant foraminifera fossils and the lowest sediment magnetic properties, is inferred to be deposited during the maximum flooding period between 8500 and 7900 cal yr BP. The branch estuary was then infilled by local sediments with a shallowing-upward subtidal-to-intertidal sequence during 7900–4300 cal yr BP. At last the fluvial plain system developed since no later than 4300 cal yr BP, favouring the rapid development of Neolithic cultures in the region.展开更多
In this study,an environmental simulation platform(ETS-02)was constructed for high-precision geodesic instruments(e.g.,absolute/relative gravimeters and inclinometers),to test the disturbances caused by environmental ...In this study,an environmental simulation platform(ETS-02)was constructed for high-precision geodesic instruments(e.g.,absolute/relative gravimeters and inclinometers),to test the disturbances caused by environmental fl uctuations.The outer layer of the platform was constructed with two sets of rectangular electromagnetic coils,which generated the required magnetic fi eld when current was applied.The inner layer was a closed cabin in which radiators were distributed such that the temperature of the experimental space inside the cabin could be controlled,by energy exchange between the radiators and a thermal controller through the fl owing liquid.A high-precision hexapod was used to simulate the tilt-related eff ect.The platform was capable of adjusting temperatures within a dynamic range of 0℃-70℃ at a resolution of 0.01℃.The noise of the power-spectrum density when the cabin was set to room temperature was measured as 0.03℃/Hz^(1/2) at 1 mHz.The magnetic field simulation had a dynamic range of±300μT and stability of 20 nT.The resolution of the ground-tilt simulation was 1 arc s.The inner space of the platform had a volume of approximately 5 m^(3),which is sufficient for most types of instruments to be tested for a general environmental coupling effect.To illustrate the application of the platform,a dual-axis inclinometer was built and tested carefully with the platform,and the accuracy of the calibration factors was found to be signifi cantly improved.展开更多
This study presents an analysis of magnetic susceptibility and natural gamma radioactivity as indirect indicators of impurities in Cretaceous limestones of the Sabinas basin, as well as of the possible relation of the...This study presents an analysis of magnetic susceptibility and natural gamma radioactivity as indirect indicators of impurities in Cretaceous limestones of the Sabinas basin, as well as of the possible relation of these physical properties with the changes in the sedimentation environment. Both of these physical properties indicate changes in the degree of impurities and the mineralogical composition of this rock, principally in its organic matter and detritus content. Considering that the sedimentation environment determines the impurities in these rocks, possible environmental conditions at different levels of the Cretaceous were suggested using the magnetic susceptibility, total gamma radiation and potassium values, as well as the uranium and thorium concentration in the limestones. The analyses suggest variations in the depth of water table of the basin, which are mainly related to transgressions and marine regressions.展开更多
The aim of this work was to analyze the effect of the magnetic field generated by the household appliances on the airborne microbial surrounding these equipment located on indoor environments with particular interest ...The aim of this work was to analyze the effect of the magnetic field generated by the household appliances on the airborne microbial surrounding these equipment located on indoor environments with particular interest in the environmental fungi.A simultaneous environmental study was carried out in locals of three different geographical places of Havana,Cuba,which have televisions,computers and an electric generator.The air samples were made by a sedimentation method using Malt Extract Agar.The concentration of total aerobic mesophilic as well as fungi and yeasts were determined in rainy and little rainy seasons by applying as factors:exposure time of dishes(5 to 60 min)and distance to the wall(0 and 1 m)at a height of 1 m above the floor.The predominant fungal genera were Cladosporium,Penicillium and Aspergillus.In the dishes that were placed at 0 and 0.5 m from the emitting sources were observed that some bacteria colonies formed inhibition halos,a great diversity of filamentous fungi and an increase in the mycelium pigmentation as well as the pigments excretion.In the rainy season,the highest amounts of fungi were obtained in all samples.In the little rain season the count of the Gram-negative bacilli increased three times the Gram-positive cocci.展开更多
基金NationalN aturalScience Foundation ofChina,N o.40471016 N o.40401007 The DoctoralFoundation ofM inistry ofEducation ofChina,N o.20030730017
文摘Here we report our recent magnetic fabric investigation of loess deposition in Shagou section, located at the northeastern Qilian Mountains, the northeastern rim of the Tibetan Plateau. On the basis of environmental magnetism data, we indicate that the variation of anisotropy of magnetic susceptibility (AMS) parameters, especially the foliation (F) and degree of anisotropy (P), might be more sensitive to the environmental change in the arid and semiarid regions than the magnetic susceptibility fluctuation. During the investigated interval, from 0.83 to 0.128 Ma, most of the middle to late Pleistocene significant climate change can be unraveled by the AMS parameters, such as the strengthening of cold/dry climate, the step drying event occurred nearly 250 ka, and the severe environmental change in MIS16. Our results also suggest that there is strong correlation between median diameter (Md) of grain size, F, and P. We propose that the AMS parameters can act as an important paleoenvironmental change indicator in the arid and semiarid regions.
基金supported by the Commonwealth Scientific Foundation for Industry of Chinese Inspection and Quarantine (No.201210071) of the Ministry of National Science and Technology of ChinaChongqing Key Laboratory of Scientific Utilization of Tobacco Resources
文摘A new kind of phenyl-functionalized magnetic fibrous mesoporous silica(Fe3 O4@Si O2@KCC-1-phenyl) was prepared by copolymerization as an efficient adsorbent for the magnetic extraction of phthalate esters from environmental water samples. The obtained Fe3 O4@Si O2@KCC-1-phenyl showed monodisperse fibrous spherical morphology, fairly strong magnetic response(29 emu/g), and an abundant π-electron system, which allowed rapid isolation of the Fe3 O4@Si O2@KCC-1-phenyl from solutions upon applying an appropriate magnetic field. Several variables that affect the extraction efficiency of the analytes,including the type of the elution solvent, amount of adsorbent, extraction time and reusability, were investigated and optimized. Under optimum conditions, the Fe3 O4@Si O2@KCC-1-phenyl was used for the extraction of four phthalate esters from environmental water samples followed by high-performance liquid chromatographic analysis. Validation experiments indicated that the developed method presented good linearity(0.1-20 ng/m L), low limit of detection(7.5-29 μg/L, S/N =3). The proposed method was applied to the determination of phthalate esters in different real water samples, with relative recoveries of 93%-103.4%and relative standard deviation of 0.8%-8.3%.
文摘In this paper, authors report some results obtained from systematic rock magnetic measurements on Core NP95 1 and Core NG93 1 , which were collected from the Prydz Bay, Eastern Antarctica and Great Wall Bay (Maxwell Bay), Western Antarctica respectively during the 11th and 9th CHINARE and a sequence of paleoclimate variations is well established based on sediment rock magnetic properties. In Antarctica, the magnetic properties show a close linkage to paleoenvironmental variations. The Core NP95 1 well recorded several paleoclimatic events, such as Heinrich event 1, Bolling Allerod warm period and Younger Dryas cold event. The Heinrich event 1 occurred at about 14 2 ka B.P., Younger Dryas cold event occurred between 11 7 ka B.P. and 10 3 ka B.P., and the boundary of Pleistocene and Holocene in Antarctica is 10 3 ka B.P.. In Holocene, two warm periods were recorded at about 10 0 ka B.P. and 6 0 ka B.P. with a little cold period between them. After 6 0 ka B.P. , two cores both recorded a cold climatic oscillation. Paleoclimate described by two cores rock magnetic measurements was simultaneously changed in Eastern and Western Antarctica during the same period two cores commonly covered.
基金supported by the National Basic Research Program of China(Grant No.2013CB934001)the National Natural Science Foundation of China(Grant Nos.51072012 and 51272015)
文摘Mn-doped ZnO nanocrystals are synthesized by a wet chemical route and treated in H2/Ar atmosphere with different H2/Ar ratios. It is found that hydrogen annealing could change the coordination environment of Mn in ZnO lattice and manipulate the magnetic properties of Mn-doped ZnO. Mn ions initially enter into interstitial sites and a Mn3＋ 06 octahedral coordination is produced in the prepared Mn-doped ZnO sample, in which the nearest neighbor Mn3＋ and 02 ions could form a Mn3＋-O2--Mn3＋ complex. After H2 annealing, interstitial Mn ions can substitute for Zn to generate the Mn2＋O4 tetrahedral coordination in the nanocrystals, in which neighboring Mn2＋ ions and H atoms could form a Mn2＋-O2--Mn2＋ complex and Mn-H-Mn bridge structure. The magnetic measurement of the as-prepared sample shows room temperature paramagnetic behavior due to the Mn3＋-O2--Mn3＋ complex, while the annealed samples exhibit their ferromagnetism, which originates from the Mn-H-Mn bridge structure and the Mn-Mn exchange interaction in the Mn2＋-O2--Mn2＋ complex.
文摘To differentiate between natural and anthropogenic particulate sources in the atmosphere in Lanzhou City, samples were collected in different sites. The dust flux was calculated and magnetic measurements were conducted. Results show a distinct pattern of variation of dust flux within a year and it agrees with the shifts of atmospheric circulation regime. The magnetic parameters indicate that natural sources are the major components of atmospheric particulate during late spring and early summer, while anthropogenic sources contribute much more during winter months. The data also support the earlier findings that magnetic parameters are effective for differentiating between particulate arising from natural sources such as soil erosion and from anthropogenic sources such as coal combustion.
基金the framework of a scientific-technical cooperation project between the Federal Institute for Geosciences and Natural Resources(BGR)and the China Geological Survey(CGS)co-funded by the German Ministry of the Economic Affairs and Energy(BMWi)and Ministry of Land and Resources of the People's Republik of China
文摘This study presents a statistical landslide susceptibility assessment(LSA) in a dynamic environment. The study area is located in the eastern part of Lanzhou, NW China. The Lanzhou area has exhibited rapid urbanization rates over the past decade associated with greening, continuous land use change, and geomorphic reshaping activities. To consider the dynamics of the environment in the LSA, multitemporal data for landslide inventories and the corresponding causal factors were collected. The weights of evidence(Wof E) method was used to perform the LSA. Three time stamps, i.e., 2000, 2012, and 2016, were selected to assess the state of landslide susceptibility over time. The results show a clear evolution of the landslide susceptibility patterns that was mainly governed by anthropogenic activities directed toward generating safer building grounds for civil infrastructure. The low and very low susceptibility areas increased by approximately 10% between 2000 and 2016. At the same time, areas of medium, high and very high susceptibility zones decreased proportionally. Based on the results, an approach to design the statistical LSA under dynamic conditions is proposed, the issues and limitations of this approach are also discussed. The study shows that under dynamic conditions, the requirements for data quantity and quality increase significantly. A dynamic environment requires greater effort to estimate the causal relations between the landslides and controlling factors as well as for model validation.
文摘In the 1990s,the American Nurses Association established a certification program called the Magnet Recognition Program through the American Nurses Credentialing Centre(ANCC)to complement the quality care provided to patients by hospitals.After the program was recognised,hospitals were identified as magnet hospitals[1].Some studies show that magnet hospitals provide a healthier working environment for nurses,accompanied by higher nurse satisfaction and better patient prognosis than non-magnet hospitals[2e5].The nursing work environment is the sum of various elements that directly or indirectly affect the patient care system[6].Improving the nursing work environment is a focal point and challenge for nursing administrators.Therefore,administrators in magnet hospitals usually apply a variety of assessment tools for effective evaluation of the nursing work environment to maintain and improve the health of the environment.
基金The National Natural Science Foundation of China under contract Nos 41306077 and 41501567the Major Program of University Natural Science Foundation of Jiangsu Province of China under contract No.14KJA170006the Natural Science Foundation of Shandong Province of China under contract No.ZR2013DQ025
文摘On the basis of measuring the magnetic parameters of sediment in Core YDZ1, combined with a grain size analysis and Carbon-14 dating, the magnetic properties of sediment and sedimentary environment in the Huanghe（Yellow River） Delta area after the last glacial maximum have been studied. The results show that the ferrimagnetic minerals of a pseudo single domain and multi domain particles dominate the magnetic properties of sediment in Core YDZ1. The imperfect anti ferrimagnetic minerals have more contribution on sediment in a depth of 24.0–22.1 m, and more stable-single domain and pseudo single domain particles exist. The susceptibility of anhysteretic remanent magnetization and the ratio of the susceptibility of anhysteretic remanent magnetization to saturation isothermal remanent magnetization show a decrease trend below depth of 24 m, a marked increase trend in a depth of 24.0–13.5 m, and a rapid decrease at depth of 13.5 m, then a fluctuation trend upward. The above two magnetic parameters and the ratio of the susceptibility of anhysteretic remanent magnetization to the mass susceptibility can be regarded as the proxy indicators for the content of clay（〈4 μm）and the fine-grained size（〈32 μm）. The sedimentary environment after the last glacial maximum in the Huanghe Delta area has experienced the fluvial facies, the tidal flat facies, the neritic facies, the pro delta facies, the delta front facies and the floodplain facies. Thickness of the Holocene transgression layer is 10.5 m and the depth of substrate is about 24 m according to the YDZ1 core. The sedimentary dynamic has a variation trend with strongweak-strong, which has been proved by the Flemming triangular schema.
基金financially funded by the National Natural Science Foundation of China (Nos. 41501005, 41476031, 41620104004)supported by China-ASEAN maritime cooperation fund: Comparative study of Holocene Sedimentary Evolution of the Yangtze River Delta and the Red River Delta
文摘The Holocene environmental evolution in coastal area, including deltas and estuaries, is vital to the Neolithic colonization in the eastern China. A 29-m long sediment core XL was obtained from the region between the Taihu Lake and Qiantang Estuary, and multiple analyses on the core sediments have been done to investigate the evolution history of the inner coastal zone of Hangzhou Bay during the Holocene. Six sedimentary facies are identified since the late Pleistocene, including the paleosol at the bottom, overlain by tidal-flat-channel complex(TFC), tidal-distributary-channel(TDC), inner estuarine basin(IEB), subtidal-to-intertidal-flat, and fluvial-plain facies. The TFC and TDC facies are dated to be formed before 8500 cal yr BP, featured by relatively coarse sediments, high magnetic properties and less abundant foraminifera, denoting the tide-influenced setting with large terrestrial inputs. The IEB facies characterized by the most abundant foraminifera fossils and the lowest sediment magnetic properties, is inferred to be deposited during the maximum flooding period between 8500 and 7900 cal yr BP. The branch estuary was then infilled by local sediments with a shallowing-upward subtidal-to-intertidal sequence during 7900–4300 cal yr BP. At last the fluvial plain system developed since no later than 4300 cal yr BP, favouring the rapid development of Neolithic cultures in the region.
基金This work was supported by National Scientifi c Instrument Development Fund(No.ZDYZ2012-1-04)State Natural Sciences Fund(No.11235004,91636112,41474163).
文摘In this study,an environmental simulation platform(ETS-02)was constructed for high-precision geodesic instruments(e.g.,absolute/relative gravimeters and inclinometers),to test the disturbances caused by environmental fl uctuations.The outer layer of the platform was constructed with two sets of rectangular electromagnetic coils,which generated the required magnetic fi eld when current was applied.The inner layer was a closed cabin in which radiators were distributed such that the temperature of the experimental space inside the cabin could be controlled,by energy exchange between the radiators and a thermal controller through the fl owing liquid.A high-precision hexapod was used to simulate the tilt-related eff ect.The platform was capable of adjusting temperatures within a dynamic range of 0℃-70℃ at a resolution of 0.01℃.The noise of the power-spectrum density when the cabin was set to room temperature was measured as 0.03℃/Hz^(1/2) at 1 mHz.The magnetic field simulation had a dynamic range of±300μT and stability of 20 nT.The resolution of the ground-tilt simulation was 1 arc s.The inner space of the platform had a volume of approximately 5 m^(3),which is sufficient for most types of instruments to be tested for a general environmental coupling effect.To illustrate the application of the platform,a dual-axis inclinometer was built and tested carefully with the platform,and the accuracy of the calibration factors was found to be signifi cantly improved.
文摘This study presents an analysis of magnetic susceptibility and natural gamma radioactivity as indirect indicators of impurities in Cretaceous limestones of the Sabinas basin, as well as of the possible relation of these physical properties with the changes in the sedimentation environment. Both of these physical properties indicate changes in the degree of impurities and the mineralogical composition of this rock, principally in its organic matter and detritus content. Considering that the sedimentation environment determines the impurities in these rocks, possible environmental conditions at different levels of the Cretaceous were suggested using the magnetic susceptibility, total gamma radiation and potassium values, as well as the uranium and thorium concentration in the limestones. The analyses suggest variations in the depth of water table of the basin, which are mainly related to transgressions and marine regressions.
基金the Ministry of Science,Technology and Environment,Cuba(PCA-2118025001)。
文摘The aim of this work was to analyze the effect of the magnetic field generated by the household appliances on the airborne microbial surrounding these equipment located on indoor environments with particular interest in the environmental fungi.A simultaneous environmental study was carried out in locals of three different geographical places of Havana,Cuba,which have televisions,computers and an electric generator.The air samples were made by a sedimentation method using Malt Extract Agar.The concentration of total aerobic mesophilic as well as fungi and yeasts were determined in rainy and little rainy seasons by applying as factors:exposure time of dishes(5 to 60 min)and distance to the wall(0 and 1 m)at a height of 1 m above the floor.The predominant fungal genera were Cladosporium,Penicillium and Aspergillus.In the dishes that were placed at 0 and 0.5 m from the emitting sources were observed that some bacteria colonies formed inhibition halos,a great diversity of filamentous fungi and an increase in the mycelium pigmentation as well as the pigments excretion.In the rainy season,the highest amounts of fungi were obtained in all samples.In the little rain season the count of the Gram-negative bacilli increased three times the Gram-positive cocci.
