Coating structural materials with Fe 3Al based intermetallics may rapidly lead to industrial application of their environment and wear resistant features. In the present study, high velocity arc spraying (HVAS) was u...Coating structural materials with Fe 3Al based intermetallics may rapidly lead to industrial application of their environment and wear resistant features. In the present study, high velocity arc spraying (HVAS) was used to in situ synthesize Fe 3Al intermetallic coating. The microstructural characterization and properties of the coating have been investigated. The microstructure was found to consist of Fe 3Al based intermetallic (D0 3 and B2) and α Fe regions together with fine oxide (α Al 2O 3) layers. TEM images of coating show that the solidified lamellae are polycrystalline and have a grain size of the order of about 150 nm , and there also exists amorphous state in some areas. It can be concluded that a very high cooling rate has been obtained during HVAS process. Moreover, the coating has relatively higher adhesion strength and microhardness, as well as lower density and porosity.展开更多
Aim To investigate the antitumor agents produced by marine-derived Penicillium flavidorsum SHK1-27.Methods The producing strain SHK1-27was fermented in a rotary shaker and bioactive metabolites in the fermentation bro...Aim To investigate the antitumor agents produced by marine-derived Penicillium flavidorsum SHK1-27.Methods The producing strain SHK1-27was fermented in a rotary shaker and bioactive metabolites in the fermentation broth were isolated through a bioassay-guided sepa-ration procedure.Structures of the bioactive compounds were investigated by spectroscopic meth-ods and their in vitro antitumor activities were assayed by the SRBmethod using K562 cells.Re-sults Eight anthraquinone derivatives were isolated from the fermentation broth of P.flavidor-sum SHK1-27 and were identified as nidurufin(1),averufin(2),8-O-methylaverufin(3),6,8-O-dimethylaverufin(4),versicolorin B(5),versicolorin A(6),versiconol(7)and averantin(8),re-spectively.Compounds 1-8 inhibited the proliferation of K562 cells and could be classified as strong(1 and 8 with the IC5o values of 12.6 and 27.7μmol·L"'respectively),moderate(2,5,6 and 7 with the ICso values of 72.4,91.0,98.7 and 93.4μmol·L-'respectively)and weak(3and 4 both with the same ICso value of>100μmol·L-')activity groups,respectively.The results showed some structure-activity relationships.Conclusion This is the first report of compounds 1-8 as the secondary metabolites of P.flavidorsum species,1,5 and 6 were isolated from fungal metabolites of the genus Penicillium for the first time,and 7 was found to occur in nature for the first time.The antitumor activities of compounds 1-8 on K562 cells were also reported for the first time in the present study.展开更多
Rock bolting has firmly used as the coal mine roof reinforcement in underground coal mine. The bolting effect of fully grouted rebar bolt is closely related to the bolt surface profile. This paper provides an experime...Rock bolting has firmly used as the coal mine roof reinforcement in underground coal mine. The bolting effect of fully grouted rebar bolt is closely related to the bolt surface profile. This paper provides an experimental study to confirm that bolt rib internal length has great influence on bolting effect. Pull-out tests were conducted using rebar bolt with different rib spacings of 12, 24, 36 and 48 mm representatively from steel tube and from concrete. Results show that peak load increases 25.3% for bolt with large rib spacing. For pull out using concrete block, the increment of peak load between large and small rib spacing is not significant, but the bolt with large rib spacing has great absorption of deformational energy than small rib spacing bolt. This study provides experimental evidence towards optimum design of rock bolt for understand coal mining industry.展开更多
Cored wires and high velocity arc spraying (HVAS) technique were applied to produce high Al content Zn-Al alloy coatings on low carbon steel substrates. The electrochemical corrosion behaviors of Zn, Al and Zn-Al coat...Cored wires and high velocity arc spraying (HVAS) technique were applied to produce high Al content Zn-Al alloy coatings on low carbon steel substrates. The electrochemical corrosion behaviors of Zn, Al and Zn-Al coatings were studied with potentiodynamic measurement in 5 % NaCl solution. Compared with pure Zn, pure Al and Zn-15Al coatings, Zn-26Al coatings show a higher corrosion resistance in salt solution. The potentiodynamic polarization tests show that the corrosion resistance of Zn-Al coatings increases as Al content is raised. Pure Al coating exhibits different electrochemical behaviors with other coatings. The corrosion initiated at the micro-pores of the coating and the underlying corrosion mechanism is very similar to that of the pitting corrosion.展开更多
The term forest transition refers to a change in forest cover over a given area from a period of net forest area loss to a period of net gain. Whether transitioning from deforestation to reforestation can lead to impr...The term forest transition refers to a change in forest cover over a given area from a period of net forest area loss to a period of net gain. Whether transitioning from deforestation to reforestation can lead to improved ecosystem services, depends on the quality and characteristics of the newly established forest cover. Using publicly available data, we examine forest transition in two regions of tropical China: Hainan Island and Xishuangbanna. We found that the overall increase of forest cover in both areas during the1980 s was due to an increase in plantation forests rather than to increases in the area covered by natural forest. We also found a time lag between the increase in overall forest cover and an increase in natural forest. On Hainan Island, natural forest continued to decline beyond the point in time when overall forest cover had started to increase, and only began to recover ten years after the turning point in 1978. In Xishuangbanna, where the transition point occurred ten years later, the decline of natural forest cover is still going on. These divergent trends underlying forest transition are concealed by the continued practice to apply the term "forest" broadly, without distinguishing between natural forests and planted forests.Due to the use of undiscriminating terminology, the loss of natural forest may go unnoticed, increasing the risk of plantation forests displacing natural forests in the course of forest transition. Our findings are important for programs related to forest management and ecosystem services improvement, including reforestation and Payments for Ecosystem Services programs.展开更多
Organic coatings are widely used to control the corrosion of steel structure. The anticorrosive property of these coatings depends on their barrier properties, making a separation between the corrosive medium and the ...Organic coatings are widely used to control the corrosion of steel structure. The anticorrosive property of these coatings depends on their barrier properties, making a separation between the corrosive medium and the substrate. But unavoidable completely small pores, cracks and other defects in organic coatings may cause ions, water, gases, and other corrosive species penetrate and distribute in the coatings, causing accumulation and swelling of coatings, so leading to the degradation of coatings. In addition, water affects the permeation of oxygen and other corrosive medium, consequently the presence of such substances at coating-metal interface promotes corrosion of metal substrate. So the absorbability of the coatings to water may be one of the most important factors in undercoating corrosion. In recent years, electrochemical impedance spectroscopy (EIS) has been established and frequently used as a non-destructive testing method for assessing the performance of organic coatings, especially for the determination of the water content in organic coatings, since the capacitance of the coatings is sensitive to the penetration of water. So from EIS it can extract a wealth of information on the electrochemical corrosion of coated steels, especially, it can be utilized to assess organic coatings used under particular surroundings. The principle, methods and application of EIS on evaluating life-span and analyzing failure mechanism of organic coatings are also introduced briefly. Combining other analysis techniques such as XRD, SEM and FTIR with electrochemical technique, it will blaze a way in studying degradation mechanism of organic coatings and estimating their lifetime.展开更多
Identification of regulators of osteoblastogenesis that can be pharmacologically targeted is a major goal in combating osteoporosis,a common disease of the elderly population. Here, unbiased kinome RNAi screening in p...Identification of regulators of osteoblastogenesis that can be pharmacologically targeted is a major goal in combating osteoporosis,a common disease of the elderly population. Here, unbiased kinome RNAi screening in primary murine osteoblasts identified cyclin-dependent kinase 5(Cdk5) as a suppressor of osteoblast differentiation in both murine and human preosteoblastic cells. Cdk5 knockdown by si RNA, genetic deletion using the Cre-lox P system, or inhibition with the small molecule roscovitine enhanced osteoblastogenesis in vitro. Roscovitine treatment significantly enhanced bone mass by increasing osteoblastogenesis and improved fracture healing in mice. Mechanistically, downregulation of Cdk5 expression increased Erk phosphorylation, resulting in enhanced osteoblast-specific gene expression. Notably, simultaneous Cdk5 and Erk depletion abrogated the osteoblastogenesis conferred by Cdk5 depletion alone, suggesting that Cdk5 regulates osteoblast differentiation through MAPK pathway modulation. We conclude that Cdk5 is a potential therapeutic target to treat osteoporosis and improve fracture healing.展开更多
文摘Coating structural materials with Fe 3Al based intermetallics may rapidly lead to industrial application of their environment and wear resistant features. In the present study, high velocity arc spraying (HVAS) was used to in situ synthesize Fe 3Al intermetallic coating. The microstructural characterization and properties of the coating have been investigated. The microstructure was found to consist of Fe 3Al based intermetallic (D0 3 and B2) and α Fe regions together with fine oxide (α Al 2O 3) layers. TEM images of coating show that the solidified lamellae are polycrystalline and have a grain size of the order of about 150 nm , and there also exists amorphous state in some areas. It can be concluded that a very high cooling rate has been obtained during HVAS process. Moreover, the coating has relatively higher adhesion strength and microhardness, as well as lower density and porosity.
基金Natural Science Founds from NSFC(39825126,30171102,30472079&30572279)National Basic Research Program of China(2006CB504100&G1998051113)+4 种基金Hi-tech Research and Development Programof China(2001AA624020&2003AA624020)Shandong Province Natural Science Foundation(Z2001C01)Qingdao Natural Science Foundation(04-2-JZ-81)China Ocean Mineral Resources R&D Association(DY105-2-04-02)Cheung Kong Scholars Programof Ministry of Education of China for the Cheung Kong Scholar(CUI Cheng-bin)
文摘Aim To investigate the antitumor agents produced by marine-derived Penicillium flavidorsum SHK1-27.Methods The producing strain SHK1-27was fermented in a rotary shaker and bioactive metabolites in the fermentation broth were isolated through a bioassay-guided sepa-ration procedure.Structures of the bioactive compounds were investigated by spectroscopic meth-ods and their in vitro antitumor activities were assayed by the SRBmethod using K562 cells.Re-sults Eight anthraquinone derivatives were isolated from the fermentation broth of P.flavidor-sum SHK1-27 and were identified as nidurufin(1),averufin(2),8-O-methylaverufin(3),6,8-O-dimethylaverufin(4),versicolorin B(5),versicolorin A(6),versiconol(7)and averantin(8),re-spectively.Compounds 1-8 inhibited the proliferation of K562 cells and could be classified as strong(1 and 8 with the IC5o values of 12.6 and 27.7μmol·L"'respectively),moderate(2,5,6 and 7 with the ICso values of 72.4,91.0,98.7 and 93.4μmol·L-'respectively)and weak(3and 4 both with the same ICso value of>100μmol·L-')activity groups,respectively.The results showed some structure-activity relationships.Conclusion This is the first report of compounds 1-8 as the secondary metabolites of P.flavidorsum species,1,5 and 6 were isolated from fungal metabolites of the genus Penicillium for the first time,and 7 was found to occur in nature for the first time.The antitumor activities of compounds 1-8 on K562 cells were also reported for the first time in the present study.
基金Financial supports for this work,provided by the Open Projects of Research Center of Coal Resources Safe Mining and Clean Utilization,Liaoning of China (No.LNTU15KF02)
文摘Rock bolting has firmly used as the coal mine roof reinforcement in underground coal mine. The bolting effect of fully grouted rebar bolt is closely related to the bolt surface profile. This paper provides an experimental study to confirm that bolt rib internal length has great influence on bolting effect. Pull-out tests were conducted using rebar bolt with different rib spacings of 12, 24, 36 and 48 mm representatively from steel tube and from concrete. Results show that peak load increases 25.3% for bolt with large rib spacing. For pull out using concrete block, the increment of peak load between large and small rib spacing is not significant, but the bolt with large rib spacing has great absorption of deformational energy than small rib spacing bolt. This study provides experimental evidence towards optimum design of rock bolt for understand coal mining industry.
基金Project(50235030)supported by the National Natural Science Foundation of China
文摘Cored wires and high velocity arc spraying (HVAS) technique were applied to produce high Al content Zn-Al alloy coatings on low carbon steel substrates. The electrochemical corrosion behaviors of Zn, Al and Zn-Al coatings were studied with potentiodynamic measurement in 5 % NaCl solution. Compared with pure Zn, pure Al and Zn-15Al coatings, Zn-26Al coatings show a higher corrosion resistance in salt solution. The potentiodynamic polarization tests show that the corrosion resistance of Zn-Al coatings increases as Al content is raised. Pure Al coating exhibits different electrochemical behaviors with other coatings. The corrosion initiated at the micro-pores of the coating and the underlying corrosion mechanism is very similar to that of the pitting corrosion.
基金funded by the National Natural Science Foundation of China (Grant 31300403)the China Postdoctoral Science Foundation (Grant 2013M540722)+2 种基金part of the CGIAR Research Program 6:Forests, Trees, and Agroforestrypart of the BMZ/GIZ "Green Rubber"(Project No. 13.1432.7-001.00)'SURUMER' (Project No. 01LL0919A) funded by the German Federal Ministry of Education and Research(BMBF) under Grant number FKZ 01LL0919
文摘The term forest transition refers to a change in forest cover over a given area from a period of net forest area loss to a period of net gain. Whether transitioning from deforestation to reforestation can lead to improved ecosystem services, depends on the quality and characteristics of the newly established forest cover. Using publicly available data, we examine forest transition in two regions of tropical China: Hainan Island and Xishuangbanna. We found that the overall increase of forest cover in both areas during the1980 s was due to an increase in plantation forests rather than to increases in the area covered by natural forest. We also found a time lag between the increase in overall forest cover and an increase in natural forest. On Hainan Island, natural forest continued to decline beyond the point in time when overall forest cover had started to increase, and only began to recover ten years after the turning point in 1978. In Xishuangbanna, where the transition point occurred ten years later, the decline of natural forest cover is still going on. These divergent trends underlying forest transition are concealed by the continued practice to apply the term "forest" broadly, without distinguishing between natural forests and planted forests.Due to the use of undiscriminating terminology, the loss of natural forest may go unnoticed, increasing the risk of plantation forests displacing natural forests in the course of forest transition. Our findings are important for programs related to forest management and ecosystem services improvement, including reforestation and Payments for Ecosystem Services programs.
文摘Organic coatings are widely used to control the corrosion of steel structure. The anticorrosive property of these coatings depends on their barrier properties, making a separation between the corrosive medium and the substrate. But unavoidable completely small pores, cracks and other defects in organic coatings may cause ions, water, gases, and other corrosive species penetrate and distribute in the coatings, causing accumulation and swelling of coatings, so leading to the degradation of coatings. In addition, water affects the permeation of oxygen and other corrosive medium, consequently the presence of such substances at coating-metal interface promotes corrosion of metal substrate. So the absorbability of the coatings to water may be one of the most important factors in undercoating corrosion. In recent years, electrochemical impedance spectroscopy (EIS) has been established and frequently used as a non-destructive testing method for assessing the performance of organic coatings, especially for the determination of the water content in organic coatings, since the capacitance of the coatings is sensitive to the penetration of water. So from EIS it can extract a wealth of information on the electrochemical corrosion of coated steels, especially, it can be utilized to assess organic coatings used under particular surroundings. The principle, methods and application of EIS on evaluating life-span and analyzing failure mechanism of organic coatings are also introduced briefly. Combining other analysis techniques such as XRD, SEM and FTIR with electrochemical technique, it will blaze a way in studying degradation mechanism of organic coatings and estimating their lifetime.
基金supported by grants from the“PAKT für Forschung und Innovation2010(Leibniz Age Net:signaling pathways in age-related diseases)”German Research Foundation(DFG)Tu220/14-1,DFG(No.Ci 216/2-1)+1 种基金DFG in the framework of Collaborative Research Center CRC1149“Danger Response,Disturbance Factors and Regenerative Potential after Trauma”(No.251293561—CRC 1149,INST 40/492-1 and INST 40/492-2)Open Access funding enabled and organized by Projekt DEAL。
文摘Identification of regulators of osteoblastogenesis that can be pharmacologically targeted is a major goal in combating osteoporosis,a common disease of the elderly population. Here, unbiased kinome RNAi screening in primary murine osteoblasts identified cyclin-dependent kinase 5(Cdk5) as a suppressor of osteoblast differentiation in both murine and human preosteoblastic cells. Cdk5 knockdown by si RNA, genetic deletion using the Cre-lox P system, or inhibition with the small molecule roscovitine enhanced osteoblastogenesis in vitro. Roscovitine treatment significantly enhanced bone mass by increasing osteoblastogenesis and improved fracture healing in mice. Mechanistically, downregulation of Cdk5 expression increased Erk phosphorylation, resulting in enhanced osteoblast-specific gene expression. Notably, simultaneous Cdk5 and Erk depletion abrogated the osteoblastogenesis conferred by Cdk5 depletion alone, suggesting that Cdk5 regulates osteoblast differentiation through MAPK pathway modulation. We conclude that Cdk5 is a potential therapeutic target to treat osteoporosis and improve fracture healing.
