A different method was employed for the preparation of a metal supported perovskite catalyst for the catalytic combustion of methane.The prepared metallic catalysts were characterized by means of X-ray diffractometer(...A different method was employed for the preparation of a metal supported perovskite catalyst for the catalytic combustion of methane.The prepared metallic catalysts were characterized by means of X-ray diffractometer(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and also by ultrasonic and thermal shock tests and catalytic activity.It was found that the process factors during the preparation,e.g.the preparation of the catalyst precursor and the coating slurry,the calcination te...展开更多
Low temperature coal tar contained a large amount of phenols, aromatic hydrocarbons and alkanes;the separation of phenols from coal tar has a great significance to the deep processing of coal tar. In this work, the se...Low temperature coal tar contained a large amount of phenols, aromatic hydrocarbons and alkanes;the separation of phenols from coal tar has a great significance to the deep processing of coal tar. In this work, the separation of m-cresol from cumene and n-heptane by liquid–liquid extraction using ionic liquids(ILs) as extractants was studied. The suitable ILs were screened by conductor-like screening model for real solvents(COSMO-RS)model and the liquid–liquid phase equilibrium(LLE) experiments were to verify the accuracy of the screening results. The extraction conditions such as extraction time, extraction temperature and mass ratio of ILs to model oils were evaluated. An internal mechanism of the m-cresol extract by ILs was revealed by COSMO-RS calculation and FT-IR. The results showed that the selected ILs can extract m-cresol effectively from cumene and nheptane, 1-ethyl-3-methylimidazolium acetate(emim CH3 COO) was the best extraction solvent. A hydrogen bond between anion of ILs and phenolic hydroxyl groups was observed. M-cresol in model oils could be extracted with extraction efficiencies up to 98.85% at an emim CH3 COO: model oils mass ratio of 0.5 and 298.15 K,emim CH3 COO could be regenerated and reused for 4 cycles without obvious decreases in extraction efficiency and extractant mass.展开更多
Working principle for a four-axis oblique intersection line welding robot is analyzed. A mathematical model for welding torch orientation angle is established, and an interpolation algorithm based on time division is ...Working principle for a four-axis oblique intersection line welding robot is analyzed. A mathematical model for welding torch orientation angle is established, and an interpolation algorithm based on time division is proposed. The algorithm makes all interpolation points fall on a required curve in theory with no accumulated errors and a direct interpolation control on the saddle-shaped curve trajectory and space orientation angle can be achieved. It is shown by MATLAB simulation that the algorithm is real-time and fully meets the precision requirement. The algorithm has been applied to real robots.展开更多
Pjridine has been generally synthesized by aldehydes and ammonia in a turbulent fluidized-bed reactor. In this paper, a novel riser reactor was proposed for pyridine synthesis. Experiment result showed that the yield ...Pjridine has been generally synthesized by aldehydes and ammonia in a turbulent fluidized-bed reactor. In this paper, a novel riser reactor was proposed for pyridine synthesis. Experiment result showed that the yield of pyridine and 3-picoline decreased, but the selectivity of pyridine over 3-picoline increased compared to turbulent fluidized-bed reactor. Based on experimental data, a modified kinetic model was used for the determination of optimal operating condition for riser reactor. The optimal operating condition of riser reactor given by this modified model was as follows： The reaction temperature of 755 K, catalyst to feedstock ratio （CTFR） of 87, residence timeof3.8sandinitialacetaldehydesconcentrationof0.0029mol.L-1 （acetaldehydes to formaldehydes ratio by mole （ATFR） of 0.65 and ammonia to aldehydes ratio by mole （ATAR） of 0.9, water contention of 63wt% （formaldehyde solution））.展开更多
In this article, we consider a lifetime distribution, the Weibull-Logarithmic distri- bution introduced by [6]. We investigate some new statistical characterizations and properties. We develop the maximum likelihood i...In this article, we consider a lifetime distribution, the Weibull-Logarithmic distri- bution introduced by [6]. We investigate some new statistical characterizations and properties. We develop the maximum likelihood inference using EM algorithm. Asymptotic properties of the MLEs are obtained and extensive simulations are conducted to assess the performance of parameter estimation. A numerical example is used to illustrate the application.展开更多
To solve the wave functions and energies of the groundstate of H＋2 ion an iteration procedure for N- dimensional potentials is applied. The iterative solutions are convergent nicely, which are comparable to earlier r...To solve the wave functions and energies of the groundstate of H＋2 ion an iteration procedure for N- dimensional potentials is applied. The iterative solutions are convergent nicely, which are comparable to earlier results based on variational methods.展开更多
The process of soft-punch hydro-forming was use.d to form some workpieces. However, it has not been completely understood until now. In this paper, based on some primary experiments, in which cups have been tried unde...The process of soft-punch hydro-forming was use.d to form some workpieces. However, it has not been completely understood until now. In this paper, based on some primary experiments, in which cups have been tried under different working conditions with the soft-punch hydro-forming process, systematical know-how about why the LDR of a metal sheet is different, how working conditions influence qualities of a work-piece, and how the deformation takes place has been achieved when simulations are employed. All these results claim that the cup depth heavily weighs on the cup wall thinning rate, and a satisfied complex part can be achieved when the contacting time between the sheet and the female die is under our control well by a movable slider, which is fixed as the bottom of the female die.展开更多
The research of gas shielding stability technology, playing a key role in underwater local dry welding, was introduced in this paper. The study includes shielding cup design, gas flow simulation, draining and welding ...The research of gas shielding stability technology, playing a key role in underwater local dry welding, was introduced in this paper. The study includes shielding cup design, gas flow simulation, draining and welding experiments. The commercial computational fluid dynamics （ CFD ） software FLUENT was applied to get and compare the speed and pressure contour images of gas in the three kinds of cup with different intake mode. The computed results show that the cup with stilling chamber on the top has the best shielding performance. The underwater welding experiment of 15 meters proves that the shielding cup with stilling chamber can offer a good dry space, the welding arc can burn stably in it and the weld quality is perfect. The research will facilitate the application of underwater local dry welding technology in the maintenance of nuclear power station widely.展开更多
This paper calculates the land (including water area) requirement for food consumption in both balanced andactual diet in China by ecological footprint analysis. To determine whether logical and actual food demands ar...This paper calculates the land (including water area) requirement for food consumption in both balanced andactual diet in China by ecological footprint analysis. To determine whether logical and actual food demands are withinnatural regenerative ability, carrying capacity (excluding forestry production) is also calculated. Results show that actualdiet patterns were ecologically friendly in the period of 1982-2004 in China, mainly because of the rural moderate dietpatterns. But actual per capita footprint already overran its corresponding logic value of 0.976ha in urban areas in 2002.Productive areas for food production can satisfy the land requirement for actual diet patterns during the researchingperiod in China, nevertheless cannot satisfy that for balanced diet pattern or solve the problem of unbalanced ecologicalfootprint. The continual rising ecological footprint of food consumption in both rural and urban areas indicates that percapita footprint will keep on increasing in China and even may be more than the suggested logic value if no relevantcountermeasures are made to regulate diet patterns. Strictly speaking, China is facing food shortage, both in quality andin quantity.展开更多
The ONIOM quantum mechanics method is used to study the reaction of one-carbon unit transfer from an imidazolidine to 6- aminouracil model with the participation of water molecules.The computation results show that in...The ONIOM quantum mechanics method is used to study the reaction of one-carbon unit transfer from an imidazolidine to 6- aminouracil model with the participation of water molecules.The computation results show that in this reaction the participation of H_2O molecule makes the energy barrier lower because of the H-bond interaction.展开更多
A metal vapor vacuum arc （MEVVA） is used in ion implantation for substrate preparation before the deposition process which would ensure the improvement of mechanical properties of the coating. Ti ion is implanted in...A metal vapor vacuum arc （MEVVA） is used in ion implantation for substrate preparation before the deposition process which would ensure the improvement of mechanical properties of the coating. Ti ion is implanted into pure magnesium surface by MEVVA implanter operated with a modified cathode. Implanting energy is kept at 45 keV and dose is set at 3 ×10^17 cm^-2. TiN coatings are deposited by magnetically filtered vacuum-arc plasma source on unimplanted and previously implanted substrates. Microstructure and phase composition are analysed using scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The property of corrosion resistance of TiN coatings was studied by CS300P electrochemistry-corrosion workstation, and the main impact factor of the corrosion resistance was also analyzed.展开更多
The mixed tris-cyclopentadienyl tetrahydrofuranato samarium complexes bis-(cyclopentadienyl) methylcyclopentadienyl tetrahadrofuranato samarium (Ⅰ) was synthesized by reaction of (C_5H_5)_2SmCl with methyl cyclopenta...The mixed tris-cyclopentadienyl tetrahydrofuranato samarium complexes bis-(cyclopentadienyl) methylcyclopentadienyl tetrahadrofuranato samarium (Ⅰ) was synthesized by reaction of (C_5H_5)_2SmCl with methyl cyclopentadienyl sodium in THF. [(C_5H_5)_2(C_5H_4CH_3)(C_4H_8O)Sm] (Ⅰ) was characterized by elemental analyses, IR spectra and MS spectra. The structure of [(C_5H_5)_2(C_5H_4CH_3)(C_4H_8O)Sm] (Ⅰ), which has two slightly different independent molecules per asymmetric unit, was elucidated through complete X-ray analysis. The crystals are monoclinic with a=1.2791(3) nm, (b=1.0467(2) nm,) c=2.6108(5) nm, β=98.22(2)°, space group Cc, R=0.0381 for 2103 observed reflection with I3σ(I).展开更多
Antimony induced crystallization of PVD （physics vapor deposition） amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si dif...Antimony induced crystallization of PVD （physics vapor deposition） amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystaUization can be observed with TEM （transmission electron microscopy）. Only a few and much smaller crystals of the order of 1 μm were formed when the antimony layer was deposited by MBE （molecular beam epitaxy） compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.展开更多
First,a class of strong limit theorems are proved by constructing two nonnegative martingales.Then they are applied to the study of all kinds of even-odd Markov chain fields and Markov chain fields defined in the pape...First,a class of strong limit theorems are proved by constructing two nonnegative martingales.Then they are applied to the study of all kinds of even-odd Markov chain fields and Markov chain fields defined in the paper.Finally,some strong limit theorems for the even-odd Markov chain fields and Markov chain fields are obtained.展开更多
This note is concerned with the absolutestability for time-varying delay Lur’e system withsector-bounded nonlinearity. Improved delay-dependentand delay-derivative-dependent stability criteria areobtained in the form...This note is concerned with the absolutestability for time-varying delay Lur’e system withsector-bounded nonlinearity. Improved delay-dependentand delay-derivative-dependent stability criteria areobtained in the form of linear matrix inequalities (LMIs)by constructing a modified augmented Lyapunov-Krasovskii (LK) functional without applying the modeltransformation or the bounding techniques for crossterms. Thus, the presented delay-dependent criteria areless conservative than those in the literature. Moreover,state feedback stabilizing controllers based on theproposed stability criteria are designed. Numericalexample demonstrates the effectiveness and superiorityof the proposed method.展开更多
This paper classifies euphemisms into two types, namely, positive euphemisms and negative euphemisms. It also analyzes the roles of euphemisms in communication and the translation strategies in the light of Skopos The...This paper classifies euphemisms into two types, namely, positive euphemisms and negative euphemisms. It also analyzes the roles of euphemisms in communication and the translation strategies in the light of Skopos Theory.展开更多
We study non-equilibrium behaviors of a particle subjected to a high-frequency cutoff noise in terms of generalized Langevin equation, where the spectrum of internal noise is considered to be of the generalized Debye ...We study non-equilibrium behaviors of a particle subjected to a high-frequency cutoff noise in terms of generalized Langevin equation, where the spectrum of internal noise is considered to be of the generalized Debye form. A closed solution is impossible even if the equation is linear, because the Laplace transform of the memory kernel is a multi-value function. We use a numerical method to calculate the velocity correlation function of a force-free particle and the probability of a particle passing over the top of an inverse harmonic potential. We indicate the nonergodicity of the second type, i.e., the auto-correlation function of the velocity approaches to non-stationary at large times. Applied to the barrier passage problem, we find and analyse a resonant phenomenon that the dependence of the cutoff frequency is nonmonotonic when the initial directional velocity of the particle is less than the critical value, the latter is determined by the passing probability equal to 0.5.展开更多
Gold nanoclusters were rapid synthesized within 3 min at 120 ℃ by using papaya juice as a capping and reducing agent(P-AuNCs). The properties of the fluorescent probe were characterized by fluorescent spectroscopy, U...Gold nanoclusters were rapid synthesized within 3 min at 120 ℃ by using papaya juice as a capping and reducing agent(P-AuNCs). The properties of the fluorescent probe were characterized by fluorescent spectroscopy, UV-vis spectroscopy, dynamic light scattering and transmission electron microscope.Based on the surface electron density increase-induced fluorescence enhancing principle, a high selective method for detection of L-lysine was developed with the as-prepared P-AuNCs coupling the fluorescence emission at 440 nm. The fluorescent probe showed high stability and good biocompatibility. Its fluorescence intensity was found to be linearly dependent on the L-lysine concentration in the range of 10.0μmol/L to 1000.0 μmol/L(R^2=0.969) with a limit of detection of 6.0μmol/L. Furthermore, the PAuNCs based approach was applied for monitoring the urine L-lysine contents, demonstrating great potential of fluorescent probes in real samples analysis.展开更多
In 1956, Tong established an asymptotic formula for the mean square of the error term of the summatory function of the Piltz divisor function d3（n）. The aim of this paper is to generalize Tong＇s method to a class o...In 1956, Tong established an asymptotic formula for the mean square of the error term of the summatory function of the Piltz divisor function d3（n）. The aim of this paper is to generalize Tong＇s method to a class of Dirichlet series L（s） which satisfies a functional equation. Let a（n） be an arithmetical function related f t to a Dirichlet series L（s）, and let E（x） be the error term of ∑＇n≤x a（n）. In this paper, after introducing a class of Diriclet series with a general functional equation （which contains the well-known Selberg class）, we establish a Tong-type identity and a Tong-type truncated formula for the error term of the Riesz mean of the coefficients of this Dirichlet series L（s）. This kind of Tong-type truncated formula could be used to study the mean square of E（x） under a certain assumption. In other words, we reduce the mean square of E（x） to the problem of finding a suitable constant σ＊ which is related to the mean square estimate of L（s）. We shall represent some results of functions in the Selberg class of degrees 2 -4.展开更多
Mercury is one of the major toxic pollutants and has many adverse effects on human health. The main mercury species in the environment or in living organisms are inorganic mercuric ion （Hg2＋） and organic methylmerc...Mercury is one of the major toxic pollutants and has many adverse effects on human health. The main mercury species in the environment or in living organisms are inorganic mercuric ion （Hg2＋） and organic methylmercury （CH3Hg＋）. Detection of the two mercury ions is a particularly active topic in the molecular sensing field during the past decade. However, efficient sensors that can sensitively detect and discriminate the two species are rare. In this work, we adopt the concept of restriction of intramolecular rotations which is the basis of aggregation induced emission, and design a molecular probe with pyridyl group as the chelating unit and 1,8-naphthalimide as the fluorescent unit for the detection of both Hg2＋ and CH3Hg＋. When the probe is free in solution, it exhibits weak fluorescence because free intramolecular rotations of the 1,8-naphthalimide moieties non-radiatively annihilate its excited state. However, upon coordination with Hg2＋ or CH3Hg＋, the rotation of 1,8-naphthalimide moieties would be restricted due to the chelation between 1,8-naphthalimide and Hg2＋ or CH3Hg＋, leading to significantly enhanced fluorescent emission. The response induced by Hg2＋ is much stronger than CH3Hg＋; but for specific detection of CH3Hg＋, we introduced a T-rich DNA fragment which could completely mask Hg2＋ in solution. Furthermore, we have employed the sensor for confocal imaging of rig2＋ and CH3Hg＋in immobilized cells. We expect the probe design tactics can be generally useful for sensing many other analytes.展开更多
基金supported by the Ministry of Science and Technology of Beijing (20081D0500500142)
文摘A different method was employed for the preparation of a metal supported perovskite catalyst for the catalytic combustion of methane.The prepared metallic catalysts were characterized by means of X-ray diffractometer(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and also by ultrasonic and thermal shock tests and catalytic activity.It was found that the process factors during the preparation,e.g.the preparation of the catalyst precursor and the coating slurry,the calcination te...
基金Supported by the National Key Projects for Fundamental Research and Development of China(2016YFB0600305).
文摘Low temperature coal tar contained a large amount of phenols, aromatic hydrocarbons and alkanes;the separation of phenols from coal tar has a great significance to the deep processing of coal tar. In this work, the separation of m-cresol from cumene and n-heptane by liquid–liquid extraction using ionic liquids(ILs) as extractants was studied. The suitable ILs were screened by conductor-like screening model for real solvents(COSMO-RS)model and the liquid–liquid phase equilibrium(LLE) experiments were to verify the accuracy of the screening results. The extraction conditions such as extraction time, extraction temperature and mass ratio of ILs to model oils were evaluated. An internal mechanism of the m-cresol extract by ILs was revealed by COSMO-RS calculation and FT-IR. The results showed that the selected ILs can extract m-cresol effectively from cumene and nheptane, 1-ethyl-3-methylimidazolium acetate(emim CH3 COO) was the best extraction solvent. A hydrogen bond between anion of ILs and phenolic hydroxyl groups was observed. M-cresol in model oils could be extracted with extraction efficiencies up to 98.85% at an emim CH3 COO: model oils mass ratio of 0.5 and 298.15 K,emim CH3 COO could be regenerated and reused for 4 cycles without obvious decreases in extraction efficiency and extractant mass.
文摘Working principle for a four-axis oblique intersection line welding robot is analyzed. A mathematical model for welding torch orientation angle is established, and an interpolation algorithm based on time division is proposed. The algorithm makes all interpolation points fall on a required curve in theory with no accumulated errors and a direct interpolation control on the saddle-shaped curve trajectory and space orientation angle can be achieved. It is shown by MATLAB simulation that the algorithm is real-time and fully meets the precision requirement. The algorithm has been applied to real robots.
基金Supported by the National Basic Research Program of China(973 Program,2012CB215000)
文摘Pjridine has been generally synthesized by aldehydes and ammonia in a turbulent fluidized-bed reactor. In this paper, a novel riser reactor was proposed for pyridine synthesis. Experiment result showed that the yield of pyridine and 3-picoline decreased, but the selectivity of pyridine over 3-picoline increased compared to turbulent fluidized-bed reactor. Based on experimental data, a modified kinetic model was used for the determination of optimal operating condition for riser reactor. The optimal operating condition of riser reactor given by this modified model was as follows： The reaction temperature of 755 K, catalyst to feedstock ratio （CTFR） of 87, residence timeof3.8sandinitialacetaldehydesconcentrationof0.0029mol.L-1 （acetaldehydes to formaldehydes ratio by mole （ATFR） of 0.65 and ammonia to aldehydes ratio by mole （ATAR） of 0.9, water contention of 63wt% （formaldehyde solution））.
基金Supported by the program for the Fundamental Research Funds for the Central Universities(2014RC042,2015JBM109)
文摘In this article, we consider a lifetime distribution, the Weibull-Logarithmic distri- bution introduced by [6]. We investigate some new statistical characterizations and properties. We develop the maximum likelihood inference using EM algorithm. Asymptotic properties of the MLEs are obtained and extensive simulations are conducted to assess the performance of parameter estimation. A numerical example is used to illustrate the application.
基金Supported by National Natural Science Foundation of China under Grant No.10847001the SRF for ROCS,SEM,and Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry
文摘To solve the wave functions and energies of the groundstate of H＋2 ion an iteration procedure for N- dimensional potentials is applied. The iterative solutions are convergent nicely, which are comparable to earlier results based on variational methods.
文摘The process of soft-punch hydro-forming was use.d to form some workpieces. However, it has not been completely understood until now. In this paper, based on some primary experiments, in which cups have been tried under different working conditions with the soft-punch hydro-forming process, systematical know-how about why the LDR of a metal sheet is different, how working conditions influence qualities of a work-piece, and how the deformation takes place has been achieved when simulations are employed. All these results claim that the cup depth heavily weighs on the cup wall thinning rate, and a satisfied complex part can be achieved when the contacting time between the sheet and the female die is under our control well by a movable slider, which is fixed as the bottom of the female die.
基金The project is supported by National Natural Science Foundation of China （40776054）.
文摘The research of gas shielding stability technology, playing a key role in underwater local dry welding, was introduced in this paper. The study includes shielding cup design, gas flow simulation, draining and welding experiments. The commercial computational fluid dynamics （ CFD ） software FLUENT was applied to get and compare the speed and pressure contour images of gas in the three kinds of cup with different intake mode. The computed results show that the cup with stilling chamber on the top has the best shielding performance. The underwater welding experiment of 15 meters proves that the shielding cup with stilling chamber can offer a good dry space, the welding arc can burn stably in it and the weld quality is perfect. The research will facilitate the application of underwater local dry welding technology in the maintenance of nuclear power station widely.
文摘This paper calculates the land (including water area) requirement for food consumption in both balanced andactual diet in China by ecological footprint analysis. To determine whether logical and actual food demands are withinnatural regenerative ability, carrying capacity (excluding forestry production) is also calculated. Results show that actualdiet patterns were ecologically friendly in the period of 1982-2004 in China, mainly because of the rural moderate dietpatterns. But actual per capita footprint already overran its corresponding logic value of 0.976ha in urban areas in 2002.Productive areas for food production can satisfy the land requirement for actual diet patterns during the researchingperiod in China, nevertheless cannot satisfy that for balanced diet pattern or solve the problem of unbalanced ecologicalfootprint. The continual rising ecological footprint of food consumption in both rural and urban areas indicates that percapita footprint will keep on increasing in China and even may be more than the suggested logic value if no relevantcountermeasures are made to regulate diet patterns. Strictly speaking, China is facing food shortage, both in quality andin quantity.
文摘The ONIOM quantum mechanics method is used to study the reaction of one-carbon unit transfer from an imidazolidine to 6- aminouracil model with the participation of water molecules.The computation results show that in this reaction the participation of H_2O molecule makes the energy barrier lower because of the H-bond interaction.
基金the Scientific Research Common Program of Beijing Municipal Commission of Education (No.KM200510017005)
文摘A metal vapor vacuum arc （MEVVA） is used in ion implantation for substrate preparation before the deposition process which would ensure the improvement of mechanical properties of the coating. Ti ion is implanted into pure magnesium surface by MEVVA implanter operated with a modified cathode. Implanting energy is kept at 45 keV and dose is set at 3 ×10^17 cm^-2. TiN coatings are deposited by magnetically filtered vacuum-arc plasma source on unimplanted and previously implanted substrates. Microstructure and phase composition are analysed using scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The property of corrosion resistance of TiN coatings was studied by CS300P electrochemistry-corrosion workstation, and the main impact factor of the corrosion resistance was also analyzed.
文摘The mixed tris-cyclopentadienyl tetrahydrofuranato samarium complexes bis-(cyclopentadienyl) methylcyclopentadienyl tetrahadrofuranato samarium (Ⅰ) was synthesized by reaction of (C_5H_5)_2SmCl with methyl cyclopentadienyl sodium in THF. [(C_5H_5)_2(C_5H_4CH_3)(C_4H_8O)Sm] (Ⅰ) was characterized by elemental analyses, IR spectra and MS spectra. The structure of [(C_5H_5)_2(C_5H_4CH_3)(C_4H_8O)Sm] (Ⅰ), which has two slightly different independent molecules per asymmetric unit, was elucidated through complete X-ray analysis. The crystals are monoclinic with a=1.2791(3) nm, (b=1.0467(2) nm,) c=2.6108(5) nm, β=98.22(2)°, space group Cc, R=0.0381 for 2103 observed reflection with I3σ(I).
文摘Antimony induced crystallization of PVD （physics vapor deposition） amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystaUization can be observed with TEM （transmission electron microscopy）. Only a few and much smaller crystals of the order of 1 μm were formed when the antimony layer was deposited by MBE （molecular beam epitaxy） compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.
基金Supported by the Special Fundation of Tianjin Education Committee(2006ZH91)Supported by the Key Discipline of Applied Mathematics at Tianjin University of Commerce(X0803)
文摘First,a class of strong limit theorems are proved by constructing two nonnegative martingales.Then they are applied to the study of all kinds of even-odd Markov chain fields and Markov chain fields defined in the paper.Finally,some strong limit theorems for the even-odd Markov chain fields and Markov chain fields are obtained.
基金The work is supported in part by The Key Technology Research for Polymerizer Cleaning Equipment by Using High-Pressure Water Jets under Grant 17032221002the Science and Technology Plan of Beijing Municipal Education Commission under Grant KM201910017002.
文摘This note is concerned with the absolutestability for time-varying delay Lur’e system withsector-bounded nonlinearity. Improved delay-dependentand delay-derivative-dependent stability criteria areobtained in the form of linear matrix inequalities (LMIs)by constructing a modified augmented Lyapunov-Krasovskii (LK) functional without applying the modeltransformation or the bounding techniques for crossterms. Thus, the presented delay-dependent criteria areless conservative than those in the literature. Moreover,state feedback stabilizing controllers based on theproposed stability criteria are designed. Numericalexample demonstrates the effectiveness and superiorityof the proposed method.
基金"北京高等学校青年英才计划项目Beijing Higher Education Young Elite Teacher Project项目编号YETP1489""北京市高等教育学会‘十二五’高等教育科学研究课题Twelfth Five-year-Plan"Higher Education Research Project of BAHE项目编号:BG125YB076"的阶段性成果
文摘This paper classifies euphemisms into two types, namely, positive euphemisms and negative euphemisms. It also analyzes the roles of euphemisms in communication and the translation strategies in the light of Skopos Theory.
文摘We study non-equilibrium behaviors of a particle subjected to a high-frequency cutoff noise in terms of generalized Langevin equation, where the spectrum of internal noise is considered to be of the generalized Debye form. A closed solution is impossible even if the equation is linear, because the Laplace transform of the memory kernel is a multi-value function. We use a numerical method to calculate the velocity correlation function of a force-free particle and the probability of a particle passing over the top of an inverse harmonic potential. We indicate the nonergodicity of the second type, i.e., the auto-correlation function of the velocity approaches to non-stationary at large times. Applied to the barrier passage problem, we find and analyse a resonant phenomenon that the dependence of the cutoff frequency is nonmonotonic when the initial directional velocity of the particle is less than the critical value, the latter is determined by the passing probability equal to 0.5.
基金financial support from the National Natural Science Foundation of China (Nos. 21575144, 91732103,21874138, 21727809, 21635008, 21621062)Chinese Academy of Sciences(No. QYZDJ-SSW-SLH034)
文摘Gold nanoclusters were rapid synthesized within 3 min at 120 ℃ by using papaya juice as a capping and reducing agent(P-AuNCs). The properties of the fluorescent probe were characterized by fluorescent spectroscopy, UV-vis spectroscopy, dynamic light scattering and transmission electron microscope.Based on the surface electron density increase-induced fluorescence enhancing principle, a high selective method for detection of L-lysine was developed with the as-prepared P-AuNCs coupling the fluorescence emission at 440 nm. The fluorescent probe showed high stability and good biocompatibility. Its fluorescence intensity was found to be linearly dependent on the L-lysine concentration in the range of 10.0μmol/L to 1000.0 μmol/L(R^2=0.969) with a limit of detection of 6.0μmol/L. Furthermore, the PAuNCs based approach was applied for monitoring the urine L-lysine contents, demonstrating great potential of fluorescent probes in real samples analysis.
基金supported by National Key Basic Research Program of China (Grant No. 2013CB834201)National Natural Science Foundation of China (Grant No. 11171344)+1 种基金Natural Science Foundation of Beijing (Grant No. 1112010)the Fundamental Research Funds for the Central Universities in China (Grant No. 2012YS01)
文摘In 1956, Tong established an asymptotic formula for the mean square of the error term of the summatory function of the Piltz divisor function d3（n）. The aim of this paper is to generalize Tong＇s method to a class of Dirichlet series L（s） which satisfies a functional equation. Let a（n） be an arithmetical function related f t to a Dirichlet series L（s）, and let E（x） be the error term of ∑＇n≤x a（n）. In this paper, after introducing a class of Diriclet series with a general functional equation （which contains the well-known Selberg class）, we establish a Tong-type identity and a Tong-type truncated formula for the error term of the Riesz mean of the coefficients of this Dirichlet series L（s）. This kind of Tong-type truncated formula could be used to study the mean square of E（x） under a certain assumption. In other words, we reduce the mean square of E（x） to the problem of finding a suitable constant σ＊ which is related to the mean square estimate of L（s）. We shall represent some results of functions in the Selberg class of degrees 2 -4.
基金funded by the National Basic Research Program of China(2013CB932800)the National Natural Science Foundation of China(21375130,31571010,21204089 and 21475132)
文摘Mercury is one of the major toxic pollutants and has many adverse effects on human health. The main mercury species in the environment or in living organisms are inorganic mercuric ion （Hg2＋） and organic methylmercury （CH3Hg＋）. Detection of the two mercury ions is a particularly active topic in the molecular sensing field during the past decade. However, efficient sensors that can sensitively detect and discriminate the two species are rare. In this work, we adopt the concept of restriction of intramolecular rotations which is the basis of aggregation induced emission, and design a molecular probe with pyridyl group as the chelating unit and 1,8-naphthalimide as the fluorescent unit for the detection of both Hg2＋ and CH3Hg＋. When the probe is free in solution, it exhibits weak fluorescence because free intramolecular rotations of the 1,8-naphthalimide moieties non-radiatively annihilate its excited state. However, upon coordination with Hg2＋ or CH3Hg＋, the rotation of 1,8-naphthalimide moieties would be restricted due to the chelation between 1,8-naphthalimide and Hg2＋ or CH3Hg＋, leading to significantly enhanced fluorescent emission. The response induced by Hg2＋ is much stronger than CH3Hg＋; but for specific detection of CH3Hg＋, we introduced a T-rich DNA fragment which could completely mask Hg2＋ in solution. Furthermore, we have employed the sensor for confocal imaging of rig2＋ and CH3Hg＋in immobilized cells. We expect the probe design tactics can be generally useful for sensing many other analytes.
