Objective To investigate the toxic effect of environmental neurotoxin MPP^＋ to C.elegans and identify the mechanisms that cause the toxicity.Methods Humanα-synuclein transgenic C.elegans was used as the animal model...Objective To investigate the toxic effect of environmental neurotoxin MPP^＋ to C.elegans and identify the mechanisms that cause the toxicity.Methods Humanα-synuclein transgenic C.elegans was used as the animal model,the toxic effect of MPP^＋ to dopamine（DA）neurons and the lifespan of worms was tested.The worms were feed with OP50 to determine whether ATP increase can rescue the worm from toxicity.ATP level and aberrant protein accumulation were analyzed in the MPP^＋ treated worms with or without OP50 addition.Results We found that MPP^＋ induced DA cell death and worm lethality,which could be prevented by OP50 treatment.OP50 exerted the protective effect by up-regulating ATP level,even though it also induced accumulation ofα-synuclein.Despite the undefined role of protein aggregation to the cell death,our results showed that the toxicity of MPP^＋ was mainly caused by the ATP depletion in theα-synuclein transgenic C.elegans.Conclusion MPP^＋ could induce DA neuronal death and worm lethality inα-synuclein transgenic C.elegans;Compared with the aggregation ofα-synuclein,the major cause of MPP^＋ toxicity appeared due to ATP depletion.展开更多
The density functional theory on the level of B3LYP/6-31G was empolyed to study the chain growth mechanism in polymerization process of α-linear olefin in TiCl3/AlEt2Cl catalytic system to synthesize drag reduction a...The density functional theory on the level of B3LYP/6-31G was empolyed to study the chain growth mechanism in polymerization process of α-linear olefin in TiCl3/AlEt2Cl catalytic system to synthesize drag reduction agent. Full parameter optimization without symmetry restrictions for reactants, products, the possible transition states, and intermediates was calculated. Vibration frequency was analyzed for all of stagnation points on the potential energy surface at the same theoretical level. The internal reaction coordinate was calculated from the transition states to reactants and products respectively. The results showed as flloes： （i） Coordination compounds were formed on the optimum configuration of TiCl3/AlEt2Cl.（ii） The transition states were formed. The energy di？erence between transition states and the coordination compounds was 40.687 kJ/mol. （iii） Double bond opened and Ti-C（4） bond fractured, and the polymerization was completed. The calculation results also showed that the chain growth mechanism did not essentially change with the increase of carbon atom number of α-linear olefin. From the relationship between polymerization activation energy and carbon atom number of the α-linear olefin, it can be seen that the α-linear olefin monomers with 6-10 carbon atoms had low activation energy and wide range. It was optimum to synthesize drag reduction agent by polymerization.展开更多
Primary rat tracheal epithelium (RTE) cells can be transformed in vitro by a-particles irradiation. Oneout of 3 isolated morphologically trans formed colonies gave rise to an immortal cell line and ultimately be-came ...Primary rat tracheal epithelium (RTE) cells can be transformed in vitro by a-particles irradiation. Oneout of 3 isolated morphologically trans formed colonies gave rise to an immortal cell line and ultimately be-came neoplastic by successive passaging. Cytogenetic analysis was performed on the cell line in order to un-derstand how the specific chromosome alterations participate in the process of neoplastic transformation ofRTE cells. The 5th, 18th, 39th passage cells and the colony cells isolated from soft agar (SA) culturing ofthe 4oth passage cells were analyzed. The results showed that the 2Oth passage cells were nontumorigenic,but the 4Oth passage cells were tumorigenic. The increase of the length of the long arrn of chromosome 15(15q+ ) was frequent at the 5th passage (67. 8% ), especially in SA cells in which it occurred in a clonalfashion (100% ) Therefore, 15q+ might be the critical gene lesion after a-particles irradiation. Mono-somy of chromosome 8 that occurred frequently at passage 5 (54% ) and 40 (53% ) might be correlatedwith earlier transformation of RTE cells. In addition, three marker chromosomes (Ml, M2 and M3)showed a passage-dependent increase’ In particular M1 and M2 that were highly frequent at passage 39(90% ) suggested that they might play an important role in the process of cell transformation.展开更多
Alpha-alumina(α-Al_2O_3) platelets were prepared via solid-state reaction using pseudo-boehmite as the starting material, while NH_4F and nano-SiO_2 were used as additives, and nitric acid was used as the binder. The...Alpha-alumina(α-Al_2O_3) platelets were prepared via solid-state reaction using pseudo-boehmite as the starting material, while NH_4F and nano-SiO_2 were used as additives, and nitric acid was used as the binder. The effect of these additives on properties of the alumina platelets was determined via scanning electron microscopy, X-ray diffraction, and measurements of the surface area and silicon content. A mechanism governing their role in the synthesis process was proposed. The results indicated that NH_4F could promote the formation of highly crystalline platelets. Addition of nano-SiO_2 could lead to increase in the diameter and reduction in the thickness of the platelets, and could also prevent their transformation to α-Al_2O_3. This addition weakened the effect of NH_4F because of the reaction of nano-SiO_2 with F-species and the formation of volatile SiF_4.展开更多
In computer aided geometric design(CAGD) ,it is often needed to produce a convexity-preserving interpolating curve according to the given planar data points. However,most existing pertinent methods cannot generate con...In computer aided geometric design(CAGD) ,it is often needed to produce a convexity-preserving interpolating curve according to the given planar data points. However,most existing pertinent methods cannot generate convexity-preserving in-terpolating transcendental curves;even constructing convexity-preserving interpolating polynomial curves,it is required to solve a system of equations or recur to a complicated iterative process. The method developed in this paper overcomes the above draw-backs. The basic idea is:first to construct a kind of trigonometric polynomial curves with a shape parameter,and interpolating trigonometric polynomial parametric curves with C2(or G1) continuity can be automatically generated without having to solve any system of equations or do any iterative computation. Then,the convexity of the constructed curves can be guaranteed by the appropriate value of the shape parameter. Performing the method is easy and fast,and the curvature distribution of the resulting interpolating curves is always well-proportioned. Several numerical examples are shown to substantiate that our algorithm is not only correct but also usable.展开更多
文摘Objective To investigate the toxic effect of environmental neurotoxin MPP^＋ to C.elegans and identify the mechanisms that cause the toxicity.Methods Humanα-synuclein transgenic C.elegans was used as the animal model,the toxic effect of MPP^＋ to dopamine（DA）neurons and the lifespan of worms was tested.The worms were feed with OP50 to determine whether ATP increase can rescue the worm from toxicity.ATP level and aberrant protein accumulation were analyzed in the MPP^＋ treated worms with or without OP50 addition.Results We found that MPP^＋ induced DA cell death and worm lethality,which could be prevented by OP50 treatment.OP50 exerted the protective effect by up-regulating ATP level,even though it also induced accumulation ofα-synuclein.Despite the undefined role of protein aggregation to the cell death,our results showed that the toxicity of MPP^＋ was mainly caused by the ATP depletion in theα-synuclein transgenic C.elegans.Conclusion MPP^＋ could induce DA neuronal death and worm lethality inα-synuclein transgenic C.elegans;Compared with the aggregation ofα-synuclein,the major cause of MPP^＋ toxicity appeared due to ATP depletion.
文摘The density functional theory on the level of B3LYP/6-31G was empolyed to study the chain growth mechanism in polymerization process of α-linear olefin in TiCl3/AlEt2Cl catalytic system to synthesize drag reduction agent. Full parameter optimization without symmetry restrictions for reactants, products, the possible transition states, and intermediates was calculated. Vibration frequency was analyzed for all of stagnation points on the potential energy surface at the same theoretical level. The internal reaction coordinate was calculated from the transition states to reactants and products respectively. The results showed as flloes： （i） Coordination compounds were formed on the optimum configuration of TiCl3/AlEt2Cl.（ii） The transition states were formed. The energy di？erence between transition states and the coordination compounds was 40.687 kJ/mol. （iii） Double bond opened and Ti-C（4） bond fractured, and the polymerization was completed. The calculation results also showed that the chain growth mechanism did not essentially change with the increase of carbon atom number of α-linear olefin. From the relationship between polymerization activation energy and carbon atom number of the α-linear olefin, it can be seen that the α-linear olefin monomers with 6-10 carbon atoms had low activation energy and wide range. It was optimum to synthesize drag reduction agent by polymerization.
文摘Primary rat tracheal epithelium (RTE) cells can be transformed in vitro by a-particles irradiation. Oneout of 3 isolated morphologically trans formed colonies gave rise to an immortal cell line and ultimately be-came neoplastic by successive passaging. Cytogenetic analysis was performed on the cell line in order to un-derstand how the specific chromosome alterations participate in the process of neoplastic transformation ofRTE cells. The 5th, 18th, 39th passage cells and the colony cells isolated from soft agar (SA) culturing ofthe 4oth passage cells were analyzed. The results showed that the 2Oth passage cells were nontumorigenic,but the 4Oth passage cells were tumorigenic. The increase of the length of the long arrn of chromosome 15(15q+ ) was frequent at the 5th passage (67. 8% ), especially in SA cells in which it occurred in a clonalfashion (100% ) Therefore, 15q+ might be the critical gene lesion after a-particles irradiation. Mono-somy of chromosome 8 that occurred frequently at passage 5 (54% ) and 40 (53% ) might be correlatedwith earlier transformation of RTE cells. In addition, three marker chromosomes (Ml, M2 and M3)showed a passage-dependent increase’ In particular M1 and M2 that were highly frequent at passage 39(90% ) suggested that they might play an important role in the process of cell transformation.
基金supported by the Technology Development(Commission) Project of SINOPEC Catalyst Co.Ltd(Grant No.14-05-01)
文摘Alpha-alumina(α-Al_2O_3) platelets were prepared via solid-state reaction using pseudo-boehmite as the starting material, while NH_4F and nano-SiO_2 were used as additives, and nitric acid was used as the binder. The effect of these additives on properties of the alumina platelets was determined via scanning electron microscopy, X-ray diffraction, and measurements of the surface area and silicon content. A mechanism governing their role in the synthesis process was proposed. The results indicated that NH_4F could promote the formation of highly crystalline platelets. Addition of nano-SiO_2 could lead to increase in the diameter and reduction in the thickness of the platelets, and could also prevent their transformation to α-Al_2O_3. This addition weakened the effect of NH_4F because of the reaction of nano-SiO_2 with F-species and the formation of volatile SiF_4.
基金Project supported by the National Basic Research Program (973) of China (No. 2004CB719400)the National Natural Science Founda-tion of China (Nos. 60673031 and 60333010) the National Natural Science Foundation for Innovative Research Groups of China (No. 60021201)
文摘In computer aided geometric design(CAGD) ,it is often needed to produce a convexity-preserving interpolating curve according to the given planar data points. However,most existing pertinent methods cannot generate convexity-preserving in-terpolating transcendental curves;even constructing convexity-preserving interpolating polynomial curves,it is required to solve a system of equations or recur to a complicated iterative process. The method developed in this paper overcomes the above draw-backs. The basic idea is:first to construct a kind of trigonometric polynomial curves with a shape parameter,and interpolating trigonometric polynomial parametric curves with C2(or G1) continuity can be automatically generated without having to solve any system of equations or do any iterative computation. Then,the convexity of the constructed curves can be guaranteed by the appropriate value of the shape parameter. Performing the method is easy and fast,and the curvature distribution of the resulting interpolating curves is always well-proportioned. Several numerical examples are shown to substantiate that our algorithm is not only correct but also usable.
