We studied the geochemical characteristics of the fluid inclusions in the Ordovician carbonates and the Oligocene Shahejie Formation sandstones from 15 wells in the Gangxi Fault Belt, Huanghua Depression. The fluid in...We studied the geochemical characteristics of the fluid inclusions in the Ordovician carbonates and the Oligocene Shahejie Formation sandstones from 15 wells in the Gangxi Fault Belt, Huanghua Depression. The fluid inclusions are all sec- ondary with gas/liquid ratio of 5%~10%. Base on Raman they are mainly composed of H2O, CO2 and CH4. The homogenization temperatures, combined with burial and geothermal history of the host rock, indicate that the fluid flows in the Shahejie Formation and the Ordovician carbonates were trapped in Neocene. Using a VG5400 mass spectrometer, the helium isotopic compositions were analyzed. Interpretation of results suggested a significant amount of mantle-derived helium mainly accumulating in the intersections of the NWW trending Xuzhuangzi and NE trending Gangxi faults. The maturity of hydrocarbon decreases from the intersection to the outside pointing out that the fluid related to the NWW trending Xuzhuangzi and NE trending Gangxi faults. These factors implied the fluid inclusions have a close relationship to the local tectonic setting. Gangxi Fault Belt experienced intensive Neo-tectonic activities in Cenozoic. Widespread faulted-depressions and strong volcanic eruptions manifested its tec- tonic status of extensional stress field. Mantle uplift caused the movement of magma that carried mantle-derived gases and deep heat flows, the deep-rooted tension faults provided the passages for the gases and heat flows to shallow crust levels.展开更多
This study is aimed at investigating the potentials of ex vivo expansion and pluri-differentiation of cryopreservation of adult human bone marrow mesenchymal stem cells (hMSCs) into chondrocytes, adipocytes and neur...This study is aimed at investigating the potentials of ex vivo expansion and pluri-differentiation of cryopreservation of adult human bone marrow mesenchymal stem cells (hMSCs) into chondrocytes, adipocytes and neurocytes. Cryopreserved hMSCs were resuscitated and cultured for 15 passages, and then induced into chondrocytes, adipocytes and neurocytes with corresponding induction medium. The induced cells were observed for morphological properties and detected for expressions of type II collagen, triglyceride or neuron-specific enolase and nestin. The result showed that the resuscitated cells could differentiate into chondrocytes after exposure to transforming growth factor 61 (TGF-~0, insulin-like growth factor I (IGF-I) and vitamin C (Vc), and uniformly changed morphologically from a spindle-like fibroblastic appearance to a polygonal shape in three weeks. The induced cells were heterochromatic to safranin O and expressed cartilage matrix-procollagenal (If) mRNA. The resuscitated cells cultured in induction medium consisting of dexamethasone, 3-isobutyl-l-methylxanthine, indomethacin and IGF-I showed adipogenesis, and lipid vacuoles accumulation was detectable after 21 d. The resuscitated hMSCs were also induced into neurocytes and expressed nestin and neuron specific endolase (NSE) that were special surface markers associated with neural cells at different stage. This study suggested that the resuscitated hMSCs should be still a population ofpluripotential cells and that it could be used for establishing an abundant bMSC reservoir for further experiment and treatment of various clinical discases.展开更多
Field investigation has revealed that the large-scale dextral strike-slip movement and the associated tectonic deformation along the Red River fault zone have the following features: geometrically, the Red River fault...Field investigation has revealed that the large-scale dextral strike-slip movement and the associated tectonic deformation along the Red River fault zone have the following features: geometrically, the Red River fault zone can be divided into three deformation regions, namely, the north, central and south regions. The north region lies on the eastern side of the Northwest Yunnan extensional taphrogenic belt, which is characterized by the 3 sets of rift-depression basins striking NNW, NNE and near N-S since the Pliocene time, and on its western side is the Lanping-Yunlong compressive deformation belt of the Paleogene to Neogene; the deformation in the central region is characterized by dextral strike-slip or shearing. The east Yunnan Miocene compressive deformation belt lies on the eastern side of the fault in the south, and the Tengtiaohe tensile fault depression belt is located on its west. In terms of tectonic geomorphology, the aforementioned deformation is represented by basin-range tectonics in the north, linear faulted valley-basins in the central part and compressive (or tensional) basins in the south. Among them, the great variance in elevation of the planation surfaces on both sides of the Cangshan-Erhai fault suggests prominent normal faulting along the Red River fault since the Pliocene. From the viewpoint of spatial-temporal evolution, the main active portion of the fault was the southern segment in the Paleogene-Miocene-Pliocene, which is represented by “tearing” from south to north. The main active portion of the fault has migrated to the northern segment since the Pliocene, especially in the late Quaternary, which is characterized by extensional slip from north to southeast. The size of the deformation region and the magnitude of deformation show that the eastern plate of the Red River fault has been an active plate of the relative movement of blocks.展开更多
Direct phase transformation of flue gas desulfurization gypsum in hot salt solution at atmospheric pres-sure was investigated.The effects of temperature,salt species,salt concentration,solids content,pH and modifier w...Direct phase transformation of flue gas desulfurization gypsum in hot salt solution at atmospheric pres-sure was investigated.The effects of temperature,salt species,salt concentration,solids content,pH and modifier were examined.The crystals obtained under different conditions and solubility of calcium sulfate in contact with solid gypsum were also determined.α-Calcium sulfate hemihydrate crystals of stubby columnar shape and regular pentahedral sides were obtained under the following conditions:salt concentration 20%-30%,operation tempera-ture 95-100 °C,solids mass content in the slurry 10%-30% and neutral pH.Thermodynamic analysis revealed that phase transformation of calcium sulfate dihydrate to α-calcium sulfate hemihydrate occurs because of the difference in solubilities between the two solid gypsum phases in this system.展开更多
The greatest advantage of remote sensing over conventional measurements lies in the opportunity to carry out detailed spatio-temporal analysis of land and ocean features on a very frequent basis. This paper analyses t...The greatest advantage of remote sensing over conventional measurements lies in the opportunity to carry out detailed spatio-temporal analysis of land and ocean features on a very frequent basis. This paper analyses the contribution of satellite imagery to atmospheric, geophysical and ocean studies and management in West Africa since the early 1980s. The detailed application of data from optical sensors (e.g. Meteosat,NOAA/AVHRR, SPOT, Landsat TM, etc.) for weather prediction, hydrogeologicah landuse/cover and cartographic studies has been acknowledged. However, the use of microwave (e.g. SAR) and optical data for ocean monitoring and studies in the sub-region is still very limited. Even though sufficient remote sensing expertise and infrastructure is perceived in the region, no clearly defined networking or database exists.展开更多
This paper introduces the discovery,composition and structure of oxalate oxidase,as well as illustrates the biological functions of this enzyme.With a comprehensive introduction upon previous researches upon gene clon...This paper introduces the discovery,composition and structure of oxalate oxidase,as well as illustrates the biological functions of this enzyme.With a comprehensive introduction upon previous researches upon gene cloning and heredity transformation of this enzyme,it indicates that heredity transformation can increase the content of oxalate oxidase within the plants and also enhance their resistance.The paper also points out the problems such as lack of gene resources and difficulty in the transformation of heterologous genes,and the focus in later researches should be laid upon the exploration of plant resources relative to this enzyme and selection of resistant species.展开更多
The emergence of Zhang Heng's seismoscope has a profound historical background. This paper intends to explore the formation and material basis of Zhang Heng's scientific thought. It appears that the simple int...The emergence of Zhang Heng's seismoscope has a profound historical background. This paper intends to explore the formation and material basis of Zhang Heng's scientific thought. It appears that the simple intention of "observing visions and distinguishing good fortune or misfortune"was his motivation to develop the seismoscope. Tracing its historical background,the authors proposed in this paper that the development of this seismoscope started around 128 A. D., and based on perceptual knowledge, two ideas about earthquakes came into being,i. e.,earthquake location could be judged according to the instrument shaking direction, and the earthquake and earth split were essentially different. In the instrument manufacture,Zhang Heng advocated a principle of "making utensils to imitate cosmos". By this principle,the following three problems were readily solved: the seismoscope imitated the response of the suspension system to earthquakes( i. e. natural seismoscope). Technically,the trigger mechanism of the latch was used for reference,and it recorded the physical evidence of earthquake occurrence by an ingenious way of a ball dropping from a dragon's mouth. The solution of these three key problems lead to the emergence of the seismoscope in 132 A. D. and the successful detection of an earthquake in 134 A. D. His invention deepened humanity's knowledge of natural laws, and promoted the development of science and technology in that time and later.展开更多
On Nov 17th,a team of researchers from the Shanghai Institute of Biochemistry and Cell Biology(SIBCB),Shanghai Institutes for Biological Sciences,CAS led by Prof.LI Jinsong reports online in Cell Research a novel te...On Nov 17th,a team of researchers from the Shanghai Institute of Biochemistry and Cell Biology(SIBCB),Shanghai Institutes for Biological Sciences,CAS led by Prof.LI Jinsong reports online in Cell Research a novel technique to induce from mice oocytes haploid embryonic stems cells(haESCs)that can fully replace the reproductive functions of sperms,greatly simplifying the otherwise complicated techniques to produce such stem cells and semi-cloned(SC)mice.It is anticipated that this will further facilitate research in the field of stem cells and embryonic development;展开更多
AIM: Differentiation of benign biliary strictures (BBS) from malignant biliary strictures (MBS) remains difficult despite improvement in imaging and endoscopic techniques. The aim of this study was to identify the cli...AIM: Differentiation of benign biliary strictures (BBS) from malignant biliary strictures (MBS) remains difficult despite improvement in imaging and endoscopic techniques. The aim of this study was to identify the clinical, biochemical and or radiological predictors of malignant biliary strictures.METHODS: We retrospectively reviewed all charts of patients who had biliary strictures (BS) on endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous cholangiography (PTC) in case of unsuccessful ERCP from March 1998 to August 2002. Patient characteristics, clinical features, biochemical, radiological and biopsy results were all recorded. Stricture etiology was determined based on cytology,biopsy or clinical follow-up. A receiver operator characteristic (ROC) curve was constructed to determine the optimal laboratory diagnostic criterion threshold in predicting MBS.RESULTS: One hundred twenty six patients with biliary strictures were enrolled, of which 72 were malignant. The mean age for BBS was 53 years compared to 62.4 years for MBS (P=0.0006). Distal bile duct stricture was mainly due to a malignant process 48.6% vs 9% (P=0.001). Alkaline phosphates and AST levels were more significantly elevated in MBS (P=0.0002). ROC curve showed that a bilirubin level of 84 μmol/L or more was the most predictive of MBS with a sensitivity of 98.6%, specificity of 59.3% and a positive likelihood ratio of 2.42 (95% CI=0.649-0.810). Proximal biliary dilatation was more frequently encountered in MBS compared to BBS, 73.8% vs39.5% (P=0.0001). Majority of BBS (87%) and MBS (78%) were managed endoscopically.CONCLUSION: A serum bilirubin level of 84 μmol/L or greater is the best predictor of MBS. Older age, proximal biliary dilatation, higher levels of bilirubin, alkaline phosphatase, ALT and AST are all associated with MBS. ERCP is necessary to diagnose and treat benign and malignant biliary strictures.展开更多
In this paper, we revisit foundations of the applications of physical measurement and Lindenmayer system to the modeling of plants. The measurement is proposed to a formal procedure and measuring the mass of leaves on...In this paper, we revisit foundations of the applications of physical measurement and Lindenmayer system to the modeling of plants. The measurement is proposed to a formal procedure and measuring the mass of leaves on a tree, tailored to branching plant structures with Simpson' s rule and Monte Carlo Methods. L-system is possible to visualize mathematical models of biological structures and processes. The formalism is illustrated using theoretical branching systems, and applied to analyze total leaves number as well as total weight of them.展开更多
This report first gives a general description of Cambodia and then discusses its topographic and geological features. Finally, the current situation concerning erosion and sediment disasters is discussed.
An exploratory study was conducted in the coastal plantation (12-and 17-year-old Sonneratia apetala) of Char Alim and Char Piya and on their adjacent barren lands at Char Rehania and Char Nurul Islam in Hatiya of Noak...An exploratory study was conducted in the coastal plantation (12-and 17-year-old Sonneratia apetala) of Char Alim and Char Piya and on their adjacent barren lands at Char Rehania and Char Nurul Islam in Hatiya of Noakhali district, in Bangladesh to determine afforestation effects on soil properties. At soil depths of 0-10, 10-30 and 30-40 cm across three different land strips viz. inland, middle and sea side in 12-and 17-year-old keora (Sonneratia apetala) plantations, soil moisture, particle density, organic matter and C, total N, pH, available P, K, Na, Ca and Mg were significantly (p≤0.05, p≤0.01, p≤0.001) higher, and soil salinity significantly (p≤0.001) lower than that in their adjacent barren lands. Soil moisture, particle density, organic matter and C, total N, pH, soil salinity, available P, K, Na, Ca and Mg of surface soil in Char Alim plantation at inland were 31.09%, 2.24 g·cm-3, 2.41%, 4.14%, 0.58%, 7.07, 0.09 dS·cm-1, 28.06 mg·L-1, 0.50 mg·L-1 11.5 mg·L-1, 3.30 mg·L-1 and 2.7 mmol·kg-1, respectively. Their corresponding values for the same depth and land position at adjacent Char Rehania barren land were 16.69%, 1.25g·cm-3, 0.43%, 0.74%, 0.25%, 6.57, 0.13 dS·cm-1, 13.07mg·L-1, 0.30 mg·L-1, 1.4 mg·L-1, 0.30 mmol·kg-1 and 0.50 mg·L-1, respectively. Soil moisture, particle density, organic matter and C, total N, pH, available P, K and Ca decreased, and soil salinity, available Na and Mg increased from inland towards sea side in the plantations. Although soil texture did not differ in most soil depths between plantation and adjacent barren land, proportion of sand particle was significantly (p≤0.01) lower and silt particle significantly (p≤0.001) in the plantations higher than that in their adjacent barren lands. In the study, evaluation of all the parameters was also done for the other pair of lands.展开更多
Although the middle construction has attracted significant attention from syntacticians, its identity still remains controversial and it is not treated as a separate grammatical category in any English learner's dict...Although the middle construction has attracted significant attention from syntacticians, its identity still remains controversial and it is not treated as a separate grammatical category in any English learner's dictionary. This article, based on the data collected from three English learner's dictionaries, investigates the middle construction in terms of its syntactic and semantic properties and the constraints on its use. It shows that the three learner's dictionaries treat the middle construction in inconsistent and problematic manners. The middle use of a verb is not distinguished from either transitive verbs with an implicit object or intransitive verbs, which may hinder English learners' acquisition of the construction. The article proposes that middle verbs should be treated as a separate subcategory of verbs on a par with transitive and intransitive verbs so that learners will become more aware of them and learn to use them correctly.展开更多
Carbon-enriched lignocelluloses are regarded as the perfect alternative for nonrenewable fossil fuel, and have a great potential to alleviate the increasing energy crisis and climate change. However, the tightly coval...Carbon-enriched lignocelluloses are regarded as the perfect alternative for nonrenewable fossil fuel, and have a great potential to alleviate the increasing energy crisis and climate change. However, the tightly covalent structure and strong intra and in- ter-molecular hydrogen bonding in lignoceUulose make it high recalcitrance to transformation due to the poor solubility in wa- ter or common organic solvents. Dissolution and transformation of lignocellulose and its constituents in ionic liquids have therefore attracted much attention recently due to the tunable physical-chemical properties. Here, ionic liquids with excellent dissolving capability for biomass and its ingredients were examined. The technologies for lignocellulose biorefining in the presence of ionic liquid solvents or catalysts were also summarized. Some pertinent suggestions for the future catalytic conver- sion and unitization of this sustained carbon-rich resource are proposed.展开更多
From the 1960 s to 1970 s, North China has been hit by a series of large earthquakes. During the past half century,geophysicists have carried out numerous surveys of the crustal and upper mantle structure, and associa...From the 1960 s to 1970 s, North China has been hit by a series of large earthquakes. During the past half century,geophysicists have carried out numerous surveys of the crustal and upper mantle structure, and associated studies in North China.They have made significant progress on several key issues in the geosciences, such as the crustal and upper mantle structure and the seismogenic environment of strong earthquakes. Deep seismic profiling results indicate a complex tectonic setting in the strong earthquake areas of North China, where a listric normal fault and a low-angle detachment in the upper crust coexist with a high-angle deep fault passing through the lower crust to the Moho beneath the hypocenter. Seismic tomography images reveal that most of the large earthquakes occurred in the transition between the high-and low-velocity zones, and the Tangshan earthquake area is characterized by a low-velocity anomaly in the middle-lower crust. Comprehensive analysis of geophysical data identified that the deep seismogenic environment in the North China extensional tectonic region is generally characterized by a low-velocity anomalous belt beneath the hypocenter, inconsistency of the deep and shallow structures in the crust, a steep crustalal-scale fault,relative lower velocities in the uppermost mantle, and local Moho uplift, etc. This indicates that the lithospheric structure of North China has strong heterogeneities. Geologically, the North China region had been a stable craton named the North China Craton or in brief the NCC, containing crustal rocks as old as ~3.8 Ga. The present-day strong seismic activity and the lower velocity of the lower crust in the NCC are much different from typical stable cratons around the world. These findings provide significant evidence for the destruction of the NCC. Although deep seismic profiling and seismic tomography have greatly enhanced knowledge about the deep-seated structure and seismogenic environment, some fundamental issues still remain and require further work.展开更多
In this paper, we present a method for constructing a Dulac function for mathematical models in population biology, in the form of systems of ordinary differential equations in the plane.
基金Project supported by the Key Laboratory of Marginal Sea Geology,South China Sea Institute of Oceanology, Chinese Academy of Sci-ences (No. MSGL0609)the Chinese Academy of Sciences (No.KZCX2-209)
文摘We studied the geochemical characteristics of the fluid inclusions in the Ordovician carbonates and the Oligocene Shahejie Formation sandstones from 15 wells in the Gangxi Fault Belt, Huanghua Depression. The fluid inclusions are all sec- ondary with gas/liquid ratio of 5%~10%. Base on Raman they are mainly composed of H2O, CO2 and CH4. The homogenization temperatures, combined with burial and geothermal history of the host rock, indicate that the fluid flows in the Shahejie Formation and the Ordovician carbonates were trapped in Neocene. Using a VG5400 mass spectrometer, the helium isotopic compositions were analyzed. Interpretation of results suggested a significant amount of mantle-derived helium mainly accumulating in the intersections of the NWW trending Xuzhuangzi and NE trending Gangxi faults. The maturity of hydrocarbon decreases from the intersection to the outside pointing out that the fluid related to the NWW trending Xuzhuangzi and NE trending Gangxi faults. These factors implied the fluid inclusions have a close relationship to the local tectonic setting. Gangxi Fault Belt experienced intensive Neo-tectonic activities in Cenozoic. Widespread faulted-depressions and strong volcanic eruptions manifested its tec- tonic status of extensional stress field. Mantle uplift caused the movement of magma that carried mantle-derived gases and deep heat flows, the deep-rooted tension faults provided the passages for the gases and heat flows to shallow crust levels.
基金Project supported by the Science Foundation (No. 2003C23015) and the Natural Science Foundation (No. Y204139) of Zhejiang Province, China
文摘This study is aimed at investigating the potentials of ex vivo expansion and pluri-differentiation of cryopreservation of adult human bone marrow mesenchymal stem cells (hMSCs) into chondrocytes, adipocytes and neurocytes. Cryopreserved hMSCs were resuscitated and cultured for 15 passages, and then induced into chondrocytes, adipocytes and neurocytes with corresponding induction medium. The induced cells were observed for morphological properties and detected for expressions of type II collagen, triglyceride or neuron-specific enolase and nestin. The result showed that the resuscitated cells could differentiate into chondrocytes after exposure to transforming growth factor 61 (TGF-~0, insulin-like growth factor I (IGF-I) and vitamin C (Vc), and uniformly changed morphologically from a spindle-like fibroblastic appearance to a polygonal shape in three weeks. The induced cells were heterochromatic to safranin O and expressed cartilage matrix-procollagenal (If) mRNA. The resuscitated cells cultured in induction medium consisting of dexamethasone, 3-isobutyl-l-methylxanthine, indomethacin and IGF-I showed adipogenesis, and lipid vacuoles accumulation was detectable after 21 d. The resuscitated hMSCs were also induced into neurocytes and expressed nestin and neuron specific endolase (NSE) that were special surface markers associated with neural cells at different stage. This study suggested that the resuscitated hMSCs should be still a population ofpluripotential cells and that it could be used for establishing an abundant bMSC reservoir for further experiment and treatment of various clinical discases.
文摘Field investigation has revealed that the large-scale dextral strike-slip movement and the associated tectonic deformation along the Red River fault zone have the following features: geometrically, the Red River fault zone can be divided into three deformation regions, namely, the north, central and south regions. The north region lies on the eastern side of the Northwest Yunnan extensional taphrogenic belt, which is characterized by the 3 sets of rift-depression basins striking NNW, NNE and near N-S since the Pliocene time, and on its western side is the Lanping-Yunlong compressive deformation belt of the Paleogene to Neogene; the deformation in the central region is characterized by dextral strike-slip or shearing. The east Yunnan Miocene compressive deformation belt lies on the eastern side of the fault in the south, and the Tengtiaohe tensile fault depression belt is located on its west. In terms of tectonic geomorphology, the aforementioned deformation is represented by basin-range tectonics in the north, linear faulted valley-basins in the central part and compressive (or tensional) basins in the south. Among them, the great variance in elevation of the planation surfaces on both sides of the Cangshan-Erhai fault suggests prominent normal faulting along the Red River fault since the Pliocene. From the viewpoint of spatial-temporal evolution, the main active portion of the fault was the southern segment in the Paleogene-Miocene-Pliocene, which is represented by “tearing” from south to north. The main active portion of the fault has migrated to the northern segment since the Pliocene, especially in the late Quaternary, which is characterized by extensional slip from north to southeast. The size of the deformation region and the magnitude of deformation show that the eastern plate of the Red River fault has been an active plate of the relative movement of blocks.
基金Supported by the National High Technology Research and Development Program of China(2006AA06Z385) the Science Foundation of Wuhan University of Science and Technology(2008RC06)
文摘Direct phase transformation of flue gas desulfurization gypsum in hot salt solution at atmospheric pres-sure was investigated.The effects of temperature,salt species,salt concentration,solids content,pH and modifier were examined.The crystals obtained under different conditions and solubility of calcium sulfate in contact with solid gypsum were also determined.α-Calcium sulfate hemihydrate crystals of stubby columnar shape and regular pentahedral sides were obtained under the following conditions:salt concentration 20%-30%,operation tempera-ture 95-100 °C,solids mass content in the slurry 10%-30% and neutral pH.Thermodynamic analysis revealed that phase transformation of calcium sulfate dihydrate to α-calcium sulfate hemihydrate occurs because of the difference in solubilities between the two solid gypsum phases in this system.
基金Supported by the Excellent Young Teachers Program of MOE, P. R. C(EYTP)
文摘The greatest advantage of remote sensing over conventional measurements lies in the opportunity to carry out detailed spatio-temporal analysis of land and ocean features on a very frequent basis. This paper analyses the contribution of satellite imagery to atmospheric, geophysical and ocean studies and management in West Africa since the early 1980s. The detailed application of data from optical sensors (e.g. Meteosat,NOAA/AVHRR, SPOT, Landsat TM, etc.) for weather prediction, hydrogeologicah landuse/cover and cartographic studies has been acknowledged. However, the use of microwave (e.g. SAR) and optical data for ocean monitoring and studies in the sub-region is still very limited. Even though sufficient remote sensing expertise and infrastructure is perceived in the region, no clearly defined networking or database exists.
基金Supported by Jilin Province Post-doctoral Project"Exploration of Quality Bean Sclerotiniose-tolerant Seeds and Genetic Resources"(00206)
文摘This paper introduces the discovery,composition and structure of oxalate oxidase,as well as illustrates the biological functions of this enzyme.With a comprehensive introduction upon previous researches upon gene cloning and heredity transformation of this enzyme,it indicates that heredity transformation can increase the content of oxalate oxidase within the plants and also enhance their resistance.The paper also points out the problems such as lack of gene resources and difficulty in the transformation of heterologous genes,and the focus in later researches should be laid upon the exploration of plant resources relative to this enzyme and selection of resistant species.
基金sponsored by the National Natural Science Foundation of China(40644019)the Special Found of Scientific Research Program for "The Optimization and Design for Reconstruction Models of Seismoscope",China Earthquake Administration
文摘The emergence of Zhang Heng's seismoscope has a profound historical background. This paper intends to explore the formation and material basis of Zhang Heng's scientific thought. It appears that the simple intention of "observing visions and distinguishing good fortune or misfortune"was his motivation to develop the seismoscope. Tracing its historical background,the authors proposed in this paper that the development of this seismoscope started around 128 A. D., and based on perceptual knowledge, two ideas about earthquakes came into being,i. e.,earthquake location could be judged according to the instrument shaking direction, and the earthquake and earth split were essentially different. In the instrument manufacture,Zhang Heng advocated a principle of "making utensils to imitate cosmos". By this principle,the following three problems were readily solved: the seismoscope imitated the response of the suspension system to earthquakes( i. e. natural seismoscope). Technically,the trigger mechanism of the latch was used for reference,and it recorded the physical evidence of earthquake occurrence by an ingenious way of a ball dropping from a dragon's mouth. The solution of these three key problems lead to the emergence of the seismoscope in 132 A. D. and the successful detection of an earthquake in 134 A. D. His invention deepened humanity's knowledge of natural laws, and promoted the development of science and technology in that time and later.
文摘On Nov 17th,a team of researchers from the Shanghai Institute of Biochemistry and Cell Biology(SIBCB),Shanghai Institutes for Biological Sciences,CAS led by Prof.LI Jinsong reports online in Cell Research a novel technique to induce from mice oocytes haploid embryonic stems cells(haESCs)that can fully replace the reproductive functions of sperms,greatly simplifying the otherwise complicated techniques to produce such stem cells and semi-cloned(SC)mice.It is anticipated that this will further facilitate research in the field of stem cells and embryonic development;
文摘AIM: Differentiation of benign biliary strictures (BBS) from malignant biliary strictures (MBS) remains difficult despite improvement in imaging and endoscopic techniques. The aim of this study was to identify the clinical, biochemical and or radiological predictors of malignant biliary strictures.METHODS: We retrospectively reviewed all charts of patients who had biliary strictures (BS) on endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous cholangiography (PTC) in case of unsuccessful ERCP from March 1998 to August 2002. Patient characteristics, clinical features, biochemical, radiological and biopsy results were all recorded. Stricture etiology was determined based on cytology,biopsy or clinical follow-up. A receiver operator characteristic (ROC) curve was constructed to determine the optimal laboratory diagnostic criterion threshold in predicting MBS.RESULTS: One hundred twenty six patients with biliary strictures were enrolled, of which 72 were malignant. The mean age for BBS was 53 years compared to 62.4 years for MBS (P=0.0006). Distal bile duct stricture was mainly due to a malignant process 48.6% vs 9% (P=0.001). Alkaline phosphates and AST levels were more significantly elevated in MBS (P=0.0002). ROC curve showed that a bilirubin level of 84 μmol/L or more was the most predictive of MBS with a sensitivity of 98.6%, specificity of 59.3% and a positive likelihood ratio of 2.42 (95% CI=0.649-0.810). Proximal biliary dilatation was more frequently encountered in MBS compared to BBS, 73.8% vs39.5% (P=0.0001). Majority of BBS (87%) and MBS (78%) were managed endoscopically.CONCLUSION: A serum bilirubin level of 84 μmol/L or greater is the best predictor of MBS. Older age, proximal biliary dilatation, higher levels of bilirubin, alkaline phosphatase, ALT and AST are all associated with MBS. ERCP is necessary to diagnose and treat benign and malignant biliary strictures.
文摘In this paper, we revisit foundations of the applications of physical measurement and Lindenmayer system to the modeling of plants. The measurement is proposed to a formal procedure and measuring the mass of leaves on a tree, tailored to branching plant structures with Simpson' s rule and Monte Carlo Methods. L-system is possible to visualize mathematical models of biological structures and processes. The formalism is illustrated using theoretical branching systems, and applied to analyze total leaves number as well as total weight of them.
文摘This report first gives a general description of Cambodia and then discusses its topographic and geological features. Finally, the current situation concerning erosion and sediment disasters is discussed.
文摘An exploratory study was conducted in the coastal plantation (12-and 17-year-old Sonneratia apetala) of Char Alim and Char Piya and on their adjacent barren lands at Char Rehania and Char Nurul Islam in Hatiya of Noakhali district, in Bangladesh to determine afforestation effects on soil properties. At soil depths of 0-10, 10-30 and 30-40 cm across three different land strips viz. inland, middle and sea side in 12-and 17-year-old keora (Sonneratia apetala) plantations, soil moisture, particle density, organic matter and C, total N, pH, available P, K, Na, Ca and Mg were significantly (p≤0.05, p≤0.01, p≤0.001) higher, and soil salinity significantly (p≤0.001) lower than that in their adjacent barren lands. Soil moisture, particle density, organic matter and C, total N, pH, soil salinity, available P, K, Na, Ca and Mg of surface soil in Char Alim plantation at inland were 31.09%, 2.24 g·cm-3, 2.41%, 4.14%, 0.58%, 7.07, 0.09 dS·cm-1, 28.06 mg·L-1, 0.50 mg·L-1 11.5 mg·L-1, 3.30 mg·L-1 and 2.7 mmol·kg-1, respectively. Their corresponding values for the same depth and land position at adjacent Char Rehania barren land were 16.69%, 1.25g·cm-3, 0.43%, 0.74%, 0.25%, 6.57, 0.13 dS·cm-1, 13.07mg·L-1, 0.30 mg·L-1, 1.4 mg·L-1, 0.30 mmol·kg-1 and 0.50 mg·L-1, respectively. Soil moisture, particle density, organic matter and C, total N, pH, available P, K and Ca decreased, and soil salinity, available Na and Mg increased from inland towards sea side in the plantations. Although soil texture did not differ in most soil depths between plantation and adjacent barren land, proportion of sand particle was significantly (p≤0.01) lower and silt particle significantly (p≤0.001) in the plantations higher than that in their adjacent barren lands. In the study, evaluation of all the parameters was also done for the other pair of lands.
文摘Although the middle construction has attracted significant attention from syntacticians, its identity still remains controversial and it is not treated as a separate grammatical category in any English learner's dictionary. This article, based on the data collected from three English learner's dictionaries, investigates the middle construction in terms of its syntactic and semantic properties and the constraints on its use. It shows that the three learner's dictionaries treat the middle construction in inconsistent and problematic manners. The middle use of a verb is not distinguished from either transitive verbs with an implicit object or intransitive verbs, which may hinder English learners' acquisition of the construction. The article proposes that middle verbs should be treated as a separate subcategory of verbs on a par with transitive and intransitive verbs so that learners will become more aware of them and learn to use them correctly.
基金financial support of the National Natural Science Foundation of China (20876055, 21076085)the Natural Science Foundation of Guangdong Province (S2011020001472)the Fundamental Research Funds for the Central Universities, SCUT
文摘Carbon-enriched lignocelluloses are regarded as the perfect alternative for nonrenewable fossil fuel, and have a great potential to alleviate the increasing energy crisis and climate change. However, the tightly covalent structure and strong intra and in- ter-molecular hydrogen bonding in lignoceUulose make it high recalcitrance to transformation due to the poor solubility in wa- ter or common organic solvents. Dissolution and transformation of lignocellulose and its constituents in ionic liquids have therefore attracted much attention recently due to the tunable physical-chemical properties. Here, ionic liquids with excellent dissolving capability for biomass and its ingredients were examined. The technologies for lignocellulose biorefining in the presence of ionic liquid solvents or catalysts were also summarized. Some pertinent suggestions for the future catalytic conver- sion and unitization of this sustained carbon-rich resource are proposed.
基金supported by the National Natural Science Foundation of China (Grant Nos. 91014006, 90914005 & 41474073)
文摘From the 1960 s to 1970 s, North China has been hit by a series of large earthquakes. During the past half century,geophysicists have carried out numerous surveys of the crustal and upper mantle structure, and associated studies in North China.They have made significant progress on several key issues in the geosciences, such as the crustal and upper mantle structure and the seismogenic environment of strong earthquakes. Deep seismic profiling results indicate a complex tectonic setting in the strong earthquake areas of North China, where a listric normal fault and a low-angle detachment in the upper crust coexist with a high-angle deep fault passing through the lower crust to the Moho beneath the hypocenter. Seismic tomography images reveal that most of the large earthquakes occurred in the transition between the high-and low-velocity zones, and the Tangshan earthquake area is characterized by a low-velocity anomaly in the middle-lower crust. Comprehensive analysis of geophysical data identified that the deep seismogenic environment in the North China extensional tectonic region is generally characterized by a low-velocity anomalous belt beneath the hypocenter, inconsistency of the deep and shallow structures in the crust, a steep crustalal-scale fault,relative lower velocities in the uppermost mantle, and local Moho uplift, etc. This indicates that the lithospheric structure of North China has strong heterogeneities. Geologically, the North China region had been a stable craton named the North China Craton or in brief the NCC, containing crustal rocks as old as ~3.8 Ga. The present-day strong seismic activity and the lower velocity of the lower crust in the NCC are much different from typical stable cratons around the world. These findings provide significant evidence for the destruction of the NCC. Although deep seismic profiling and seismic tomography have greatly enhanced knowledge about the deep-seated structure and seismogenic environment, some fundamental issues still remain and require further work.
文摘In this paper, we present a method for constructing a Dulac function for mathematical models in population biology, in the form of systems of ordinary differential equations in the plane.