Aptian is characterized by widespread deposition of organic-rich sediment.The Aptian bitumen limestone horizon,which is thin decimetre-thick sequences,locally crops out in the Kircaova area,Eastern Black Sea Region(Ea...Aptian is characterized by widespread deposition of organic-rich sediment.The Aptian bitumen limestone horizon,which is thin decimetre-thick sequences,locally crops out in the Kircaova area,Eastern Black Sea Region(Eastern Pontides).They are well correlated with Aptian bitumen limestone in the other Tethys Reams.They are proposed as episodes of increased organic matter.However,background factors controlling organic matter enrichment are poorly known.In this study,we present new inorganic geochemistry,including trace elements,rare earth elements(REE),redox-sensitive elements(RSE),stable-isotopes(δ~(18)O andδ~(13)C),and total organic carbon(TOC).We integrated new geochemical data with existing stratigraphy,paleontology,and organic chemistry data to provide new insight into the depositional environment and paleoclimate conditions during Aptian.The lacustrine bitumen limestone(LBL)samples have variedδ~(13)C(ave.-1.45‰)andδ~(18)O(ave.-4.50‰).They possess distinct REE patterns,with an average of REE(ave.14.45 ppm)and Y/Ho(ave.35)ratios.In addition,they have variable Nd/YbN(0.28-0.81;ave.0.56)and Ce/Ce*(0.68-0.97;ave.0.86),and relatively high Eu^(*)/Eu(1.23-1.53;ave.1.35).They display seawater signatures with reduced oxygen conditions.The enrichment in RSE(Mo,Cu,Ni,and Zn)and the low Mo/TOC(0.70-3.69;ave.2.41)support a certain degree of water restriction.The high Sr/Ba,Sr/Cu,Ga/Rb,and K/Al records of the LBL facies suggest hot house climatic conditions.The sedimentary environment was probably an isolated basin that is transformed from the marine basin.In addition to depositional conditions,the regional parameters such as the climate,increased run-off period,nutrient levels,alkalinity level,and dominant carbonate producers favored the enrichment in organic matter of LBL facies.Thus,extreme greenhouse palaeoclimate conditions have an important role in organic matter enrichment in the isolated basin.Our results are conformable with the published data from marine,semi-restricted basin,and lacustrine settings in the different parts of the Tethys margin.Thus,this approach provides the first insight into the Aptian greenhouse paleo-climate conditions of the Eastern Black Sea Region,NE Turkey.展开更多
The effects of exposure to UV-B radiation, 280-315 nm, and dark or dark repair conditions on the early development of Chondrus ocellatus Holm collected from Qingdao coast were studied under the laboratory condition. A...The effects of exposure to UV-B radiation, 280-315 nm, and dark or dark repair conditions on the early development of Chondrus ocellatus Holm collected from Qingdao coast were studied under the laboratory condition. After being exposed to different doses [0, 36, 72, 108, 144 and 180 J/（m2.d）] of UV-B radiation, one treatment of tetraspores were put back to normal culture condition （PAR）, the other treatment were put into dark condition to repair for 2 h. During the cultivation, the diameter of the tetraspores were recorded every 4 d till the 50th day when vertical branches formed in all treatments. Then at the 50th day, CPDs, phycoerythrin, chlorophyll a and MAAs （Palythine and asterina-330） were measured. The results showed that low doses UV-B radiation could significantly accelerate the growth rate of the rate reduced gradually with UV-B radiation keep on tetraspores of C. ocellatus and the growth increasing. The variation trend of both the phycoerythrin and chlorophyll a concentration reduced significantly （P 〈0.05） once given the UV- B radiation. Under UV-B stress, the CPDs were induced, and the concentrations of CPDs were significant low in dark repair groups. The data of MAAs analyzed by LC/MS in the tetraspores of C. ocellatus suggested that there were two MAAs formed （palythine and asterina-330） after UV-B radiation induced, and low dose of UV-B irradiation could significantly induced the concentration of MAAs. From the growth and development state of the tetraspores, negative effects of UV-B radiation on the dark repair groups were more serious than PAR.展开更多
C/C minicomposites were manufactured by CVI with propylene as resource gas and Ar as diluent gas. Effects of deposition temperature, the flow rate of propylene and total system pressure on the microstructure...C/C minicomposites were manufactured by CVI with propylene as resource gas and Ar as diluent gas. Effects of deposition temperature, the flow rate of propylene and total system pressure on the microstructure of C/C minicomposites were investigated. Deposition conditions are as follows: deposition temperature ranging from 870℃ to 1000℃, the flow rate of propylene from 10 to 60 ml/min, and total system pressure from 3 to 16kPa. The results revealed: The deposit distributes non uniformly as increasing the deposition temperature or total system pressure. The effect of the flow rate of propylene on the distribution of deposit observes different principles at different deposition temperatures. If the deposition temperature rises to 900℃, the deposit distributes more non uniformly as increasing the flow rate of propylene. The morphology of deposit varies with deposition condition, such as smooth, droplet like or spike like. Deposition mechanism varies with deposition condition. It can be surface reaction nucleation and growth, heterogeneous nucleation of liquid droplet on carbon fiber or gas borne nuclei growth. With the principle of nuclei growth of crystal and the method of phenomenology, the changes of deposition mechanism and the morphology of pyrolytic carbon with deposition condition were explained successfully. The effect of deposition condition on deposit homogeneity stems from the effect of deposition condition on the CVI kinetics and the deposition mechanism of pyrolytic carbon.展开更多
C/C-SiC braking composites,based on reinforcement of carbon fibers and matrices of carbon and silicon carbide,were fabricated by warm compaction and in situ reaction process.The tribological characteristics of C/C-SiC...C/C-SiC braking composites,based on reinforcement of carbon fibers and matrices of carbon and silicon carbide,were fabricated by warm compaction and in situ reaction process.The tribological characteristics of C/C-SiC braking composites under dry and wet conditions were investigated by means of MM-1000 type of friction testing machine.The influence of dry and wet conditions on the tribological characteristics of the C/C-SiC composites was ascertained.Under dry condition,C/C-SiC braking composites show superior tribological characteristics,including high coefficient of friction (0.38),good abrasive resistance (thickness loss is 1.10 μm per cycle) and steady breaking.The main wear mechanism is plastic deformation and abrasion caused by plough.Under wet condition,frictional films form on the worn surface.The coefficient of friction (0.35) could maintain mostly,and the thickness loss (0.70 μm per cycle) reduces to a certain extent.Furthermore,braking curves are steady and adhesion and oxidation are the main wear mechanisms.展开更多
Let S be a semigroup with zero and an S-act be a centered left S-act. This paper is devoted to the study of chain conditions on PS-acts. We prove that a PS-act having finite decomposition has ACC （DCC） on all subact...Let S be a semigroup with zero and an S-act be a centered left S-act. This paper is devoted to the study of chain conditions on PS-acts. We prove that a PS-act having finite decomposition has ACC （DCC） on all subacts if it has ACC （DCC） on essential subacts. Moreover, a PS-act with ACC （DCC） on essential subacts has ACC （DCC） on all subacts if and only if it has finite decomposition. We characterize the structure of a PS-act and generalize some results of the Goldie dimension and semisimple S-acts.展开更多
Objective: Conditioned taste preference(CTP) is a taste learning reflex by which an animal learns to prefer a substance which tastes not well and has been studied with much interest in recent years. However, the neura...Objective: Conditioned taste preference(CTP) is a taste learning reflex by which an animal learns to prefer a substance which tastes not well and has been studied with much interest in recent years. However, the neural substrates of CTP are less known. This study aimed to determine the possible neural pathways of CTP and whether serum leptin level and the leptin receptor(OB-Rb) in the hind brain are involved following CTP formation. Methods: We established CTP of quinine in rats with a 2-bottle preference test. The serum leptin concentrations were detected, the expression of c-fos in the rat brain was tested to determine the nuclei in relation with establishment of CTP. Finally, the OB-Rb m RNA expression was examined by RT-q PCR assay in parabrachial nucleus(PBN) and the nucleus of the solitary tract(NST) of the hind brain. Results: Compared with control group, the level of serum leptin was higher in the CTP group(4.58 ± 0.52 vs 1.67 ± 0.25 μg/L, P<0. 01); increased c-fos positive cells were found in the anterior hypothalamus(AH, 221.75 ± 4.96 vs. 178.50±6.63 cells/mm^2, P<0.05), the basal lateral amygdala(BLA, 70.75±6.17 vs 56.50±3.62 cells/mm^2, P<0.05) and the nucleus of the solitary tract(NST, 41.25±1.32 vs 32.50±1.02 cells/mm^2, P<0.05). But in ventromedial nucleus of the hypothalamus(VMH, 20.75±2.73 vs 38.5±1.54 per 1 mm^2, P<005), PBN(21.50 ±2.24 vs 36.25±1.49 cells/mm^2, P<0.05) and the central nucleus of the amygdala(Ce A, 22.25±1.53 vs 35.50 ±2.11 cells/mm^2, P<0.05), the number of c-fos positive cells was decreased in the CTP group. In addition, we found OB-Rb m RNA expression in PBN of CTP group rats was higher than that of control group(0.95±0.055 vs 0.57± 0.034, P<0.05), while there was no significant difference of OB-Rb m RNA expression in NST between the two groups. Conclusion: Nuclei AH, BLA, NST, VMH, PBN and Ce A participate in the formation of CTP. Leptin and its receptor in PBN may be involved in the formation and maintenance of CTP.展开更多
In the present work, we numerically study the laminar natural convection of a nanofluid confined in a square cavity. The vertical walls are assumed to be insulated, non-conducting, and impermeable to mass transfer. Th...In the present work, we numerically study the laminar natural convection of a nanofluid confined in a square cavity. The vertical walls are assumed to be insulated, non-conducting, and impermeable to mass transfer. The horizontal walls are differentially heated, and the low is maintained at hot condition (sinusoidal) when the high one is cold. The objective of this work is to develop a new height accurate method for solving heat transfer equations. The new method is a Fourth Order Compact (F.O.C). This work aims to show the interest of the method and understand the effect of the presence of nanofluids in closed square systems on the natural convection mechanism. The numerical simulations are performed for Prandtl number ( ), the Rayleigh numbers varying between and for different volume fractions varies between 0% and 10% for the nanofluid (water + Cu).展开更多
基于室内物理模型试验和原位锚固试验,对基于高模数硅酸钾溶液-（粉煤灰＋粉土）（PS-（F＋C））浆液的木锚杆锚固系统在夯土介质中进行了拉拔测试与杆体-浆体界面应变监测,研究了该锚固系统的锚固性能与破坏模式、杆体-浆体界面剪应力...基于室内物理模型试验和原位锚固试验,对基于高模数硅酸钾溶液-（粉煤灰＋粉土）（PS-（F＋C））浆液的木锚杆锚固系统在夯土介质中进行了拉拔测试与杆体-浆体界面应变监测,研究了该锚固系统的锚固性能与破坏模式、杆体-浆体界面剪应力分布与传递特征。结果表明：该锚固系统室内试验极限锚固力（24～38 k N）远大于现场试验值（2.5～8 k N）;锚固系统具有低弹性强塑性特征,表现出极强的延性;在荷载进程中杆体-浆体界面的应力分布与传递特征具有多峰值分布、高值往往出现在锚固末端、压应力出现等特征,表明该锚固系统兼有拉力型和压力型全长黏结性锚固系统的特点;该系统适合于夯筑土遗址锚固,与遗址具有良好的物理力学兼容性。展开更多
文摘Aptian is characterized by widespread deposition of organic-rich sediment.The Aptian bitumen limestone horizon,which is thin decimetre-thick sequences,locally crops out in the Kircaova area,Eastern Black Sea Region(Eastern Pontides).They are well correlated with Aptian bitumen limestone in the other Tethys Reams.They are proposed as episodes of increased organic matter.However,background factors controlling organic matter enrichment are poorly known.In this study,we present new inorganic geochemistry,including trace elements,rare earth elements(REE),redox-sensitive elements(RSE),stable-isotopes(δ~(18)O andδ~(13)C),and total organic carbon(TOC).We integrated new geochemical data with existing stratigraphy,paleontology,and organic chemistry data to provide new insight into the depositional environment and paleoclimate conditions during Aptian.The lacustrine bitumen limestone(LBL)samples have variedδ~(13)C(ave.-1.45‰)andδ~(18)O(ave.-4.50‰).They possess distinct REE patterns,with an average of REE(ave.14.45 ppm)and Y/Ho(ave.35)ratios.In addition,they have variable Nd/YbN(0.28-0.81;ave.0.56)and Ce/Ce*(0.68-0.97;ave.0.86),and relatively high Eu^(*)/Eu(1.23-1.53;ave.1.35).They display seawater signatures with reduced oxygen conditions.The enrichment in RSE(Mo,Cu,Ni,and Zn)and the low Mo/TOC(0.70-3.69;ave.2.41)support a certain degree of water restriction.The high Sr/Ba,Sr/Cu,Ga/Rb,and K/Al records of the LBL facies suggest hot house climatic conditions.The sedimentary environment was probably an isolated basin that is transformed from the marine basin.In addition to depositional conditions,the regional parameters such as the climate,increased run-off period,nutrient levels,alkalinity level,and dominant carbonate producers favored the enrichment in organic matter of LBL facies.Thus,extreme greenhouse palaeoclimate conditions have an important role in organic matter enrichment in the isolated basin.Our results are conformable with the published data from marine,semi-restricted basin,and lacustrine settings in the different parts of the Tethys margin.Thus,this approach provides the first insight into the Aptian greenhouse paleo-climate conditions of the Eastern Black Sea Region,NE Turkey.
文摘The effects of exposure to UV-B radiation, 280-315 nm, and dark or dark repair conditions on the early development of Chondrus ocellatus Holm collected from Qingdao coast were studied under the laboratory condition. After being exposed to different doses [0, 36, 72, 108, 144 and 180 J/（m2.d）] of UV-B radiation, one treatment of tetraspores were put back to normal culture condition （PAR）, the other treatment were put into dark condition to repair for 2 h. During the cultivation, the diameter of the tetraspores were recorded every 4 d till the 50th day when vertical branches formed in all treatments. Then at the 50th day, CPDs, phycoerythrin, chlorophyll a and MAAs （Palythine and asterina-330） were measured. The results showed that low doses UV-B radiation could significantly accelerate the growth rate of the rate reduced gradually with UV-B radiation keep on tetraspores of C. ocellatus and the growth increasing. The variation trend of both the phycoerythrin and chlorophyll a concentration reduced significantly （P 〈0.05） once given the UV- B radiation. Under UV-B stress, the CPDs were induced, and the concentrations of CPDs were significant low in dark repair groups. The data of MAAs analyzed by LC/MS in the tetraspores of C. ocellatus suggested that there were two MAAs formed （palythine and asterina-330） after UV-B radiation induced, and low dose of UV-B irradiation could significantly induced the concentration of MAAs. From the growth and development state of the tetraspores, negative effects of UV-B radiation on the dark repair groups were more serious than PAR.
文摘C/C minicomposites were manufactured by CVI with propylene as resource gas and Ar as diluent gas. Effects of deposition temperature, the flow rate of propylene and total system pressure on the microstructure of C/C minicomposites were investigated. Deposition conditions are as follows: deposition temperature ranging from 870℃ to 1000℃, the flow rate of propylene from 10 to 60 ml/min, and total system pressure from 3 to 16kPa. The results revealed: The deposit distributes non uniformly as increasing the deposition temperature or total system pressure. The effect of the flow rate of propylene on the distribution of deposit observes different principles at different deposition temperatures. If the deposition temperature rises to 900℃, the deposit distributes more non uniformly as increasing the flow rate of propylene. The morphology of deposit varies with deposition condition, such as smooth, droplet like or spike like. Deposition mechanism varies with deposition condition. It can be surface reaction nucleation and growth, heterogeneous nucleation of liquid droplet on carbon fiber or gas borne nuclei growth. With the principle of nuclei growth of crystal and the method of phenomenology, the changes of deposition mechanism and the morphology of pyrolytic carbon with deposition condition were explained successfully. The effect of deposition condition on deposit homogeneity stems from the effect of deposition condition on the CVI kinetics and the deposition mechanism of pyrolytic carbon.
基金Project(2006AA03Z560) supported by the Hi-tech Research and Development Program of ChinaProject(06JJ1007) supported by Excellent Youth of Hunan Province, China
文摘C/C-SiC braking composites,based on reinforcement of carbon fibers and matrices of carbon and silicon carbide,were fabricated by warm compaction and in situ reaction process.The tribological characteristics of C/C-SiC braking composites under dry and wet conditions were investigated by means of MM-1000 type of friction testing machine.The influence of dry and wet conditions on the tribological characteristics of the C/C-SiC composites was ascertained.Under dry condition,C/C-SiC braking composites show superior tribological characteristics,including high coefficient of friction (0.38),good abrasive resistance (thickness loss is 1.10 μm per cycle) and steady breaking.The main wear mechanism is plastic deformation and abrasion caused by plough.Under wet condition,frictional films form on the worn surface.The coefficient of friction (0.35) could maintain mostly,and the thickness loss (0.70 μm per cycle) reduces to a certain extent.Furthermore,braking curves are steady and adhesion and oxidation are the main wear mechanisms.
基金The NSF (10571181,10471045) of Chinathe NSF (021073, Z02017) of Guangdong Province
文摘Let S be a semigroup with zero and an S-act be a centered left S-act. This paper is devoted to the study of chain conditions on PS-acts. We prove that a PS-act having finite decomposition has ACC （DCC） on all subacts if it has ACC （DCC） on essential subacts. Moreover, a PS-act with ACC （DCC） on essential subacts has ACC （DCC） on all subacts if and only if it has finite decomposition. We characterize the structure of a PS-act and generalize some results of the Goldie dimension and semisimple S-acts.
基金supported by the National Natural Science Foundation of China(31171052)
文摘Objective: Conditioned taste preference(CTP) is a taste learning reflex by which an animal learns to prefer a substance which tastes not well and has been studied with much interest in recent years. However, the neural substrates of CTP are less known. This study aimed to determine the possible neural pathways of CTP and whether serum leptin level and the leptin receptor(OB-Rb) in the hind brain are involved following CTP formation. Methods: We established CTP of quinine in rats with a 2-bottle preference test. The serum leptin concentrations were detected, the expression of c-fos in the rat brain was tested to determine the nuclei in relation with establishment of CTP. Finally, the OB-Rb m RNA expression was examined by RT-q PCR assay in parabrachial nucleus(PBN) and the nucleus of the solitary tract(NST) of the hind brain. Results: Compared with control group, the level of serum leptin was higher in the CTP group(4.58 ± 0.52 vs 1.67 ± 0.25 μg/L, P<0. 01); increased c-fos positive cells were found in the anterior hypothalamus(AH, 221.75 ± 4.96 vs. 178.50±6.63 cells/mm^2, P<0.05), the basal lateral amygdala(BLA, 70.75±6.17 vs 56.50±3.62 cells/mm^2, P<0.05) and the nucleus of the solitary tract(NST, 41.25±1.32 vs 32.50±1.02 cells/mm^2, P<0.05). But in ventromedial nucleus of the hypothalamus(VMH, 20.75±2.73 vs 38.5±1.54 per 1 mm^2, P<005), PBN(21.50 ±2.24 vs 36.25±1.49 cells/mm^2, P<0.05) and the central nucleus of the amygdala(Ce A, 22.25±1.53 vs 35.50 ±2.11 cells/mm^2, P<0.05), the number of c-fos positive cells was decreased in the CTP group. In addition, we found OB-Rb m RNA expression in PBN of CTP group rats was higher than that of control group(0.95±0.055 vs 0.57± 0.034, P<0.05), while there was no significant difference of OB-Rb m RNA expression in NST between the two groups. Conclusion: Nuclei AH, BLA, NST, VMH, PBN and Ce A participate in the formation of CTP. Leptin and its receptor in PBN may be involved in the formation and maintenance of CTP.
文摘In the present work, we numerically study the laminar natural convection of a nanofluid confined in a square cavity. The vertical walls are assumed to be insulated, non-conducting, and impermeable to mass transfer. The horizontal walls are differentially heated, and the low is maintained at hot condition (sinusoidal) when the high one is cold. The objective of this work is to develop a new height accurate method for solving heat transfer equations. The new method is a Fourth Order Compact (F.O.C). This work aims to show the interest of the method and understand the effect of the presence of nanofluids in closed square systems on the natural convection mechanism. The numerical simulations are performed for Prandtl number ( ), the Rayleigh numbers varying between and for different volume fractions varies between 0% and 10% for the nanofluid (water + Cu).
文摘基于室内物理模型试验和原位锚固试验,对基于高模数硅酸钾溶液-（粉煤灰＋粉土）（PS-（F＋C））浆液的木锚杆锚固系统在夯土介质中进行了拉拔测试与杆体-浆体界面应变监测,研究了该锚固系统的锚固性能与破坏模式、杆体-浆体界面剪应力分布与传递特征。结果表明：该锚固系统室内试验极限锚固力（24～38 k N）远大于现场试验值（2.5～8 k N）;锚固系统具有低弹性强塑性特征,表现出极强的延性;在荷载进程中杆体-浆体界面的应力分布与传递特征具有多峰值分布、高值往往出现在锚固末端、压应力出现等特征,表明该锚固系统兼有拉力型和压力型全长黏结性锚固系统的特点;该系统适合于夯筑土遗址锚固,与遗址具有良好的物理力学兼容性。
