The monument thermal effect(MTE)displacements could result in periodical signals with several mil-limeters magnitudes in the vertical and horizontal GPS position time series.However,the interaction ofvarious origins o...The monument thermal effect(MTE)displacements could result in periodical signals with several mil-limeters magnitudes in the vertical and horizontal GPS position time series.However,the interaction ofvarious origins of periodic signals in GPS observations makes it difficult to isolate the millimeter-levelMTE displacement from other signals and noises.In this study,to assess the diurnal and semidiurnalsignals induced by MTE,we processed 12 very short GPS baselines(VSGB)with length<150 m.Themonument pairs for each baseline differ in their heights,horizontal structure,or base foundations.Meanwhile,two zero-baselines were also processed as the control group.Results showed that the sea-sonal signals observed in VSGB time series in the horizontal and vertical directions,were mainly inducedby seasonal MTE.Time-varying diurnal and semidiurnal signals with amplitude up to 4 mm wereobserved in the vertical direction for baselines with monument height difference(MHD)larger than10 m.Horizontal diurnal signal with an amplitude of about 2 mm was also detected for baselines withnon-axisymmetric monument structure.The orientation of the detected horizontal displacement wascoherent with the direction of daily temperature variation(DTV)driven by direct solar radiation,whichindicates that the diurnal and semidiurnal signals are likely induced by MTE.The observed high-frequency MTE displacements,if not well modeled and removed,may propagate into spurious long-term signals and bias the velocity estimation in the daily GPS time series.展开更多
The La-Mg-Ni-system （PuNi3-type） La2Mg （Ni0.85 Co0.15 ）9M0.1 （ M = B, Cr） hydrogen storage etectrode alloys were prepared by casting and rapid quenching. The electrochemical performances and microstructures of t...The La-Mg-Ni-system （PuNi3-type） La2Mg （Ni0.85 Co0.15 ）9M0.1 （ M = B, Cr） hydrogen storage etectrode alloys were prepared by casting and rapid quenching. The electrochemical performances and microstructures of the as-cast and quenched alloys were determined and measured. The effects of rapid quenching on the microstructures and electrochemical properties of the alloys were investigated in detail. The obtained results show that the alloys are composed of the （La, Mg） Ni3 phase （PuNi3-type structure） and the LaNi5 phase, as well as the small amount of the LaNi2 phase. A trace of the Ni2B phase exists in the as-cast alloy containing boron, and the Ni2B phase in the alloy nearly disappears after rapid quenching. The relative amount of each phase in the alloys depends on the quenching rate. The rapid quenching technique can greatly improve the electrochemical performance of the alloy, and the effect of rapid quenching on the activation performances of the alloys is minor. Rapid quenching enhances the cycle stability of the alloy, and the cycle life of the alloy increases with the increase of the quenching rate.展开更多
The 150 kV bouncer modulator is designed to drive the 10 MW multi-beam klystron for the DESYTESLA Test Facility. The modulator is different from the 10 kV modulators previously built at Fermilab. First, thenew 150 kV ...The 150 kV bouncer modulator is designed to drive the 10 MW multi-beam klystron for the DESYTESLA Test Facility. The modulator is different from the 10 kV modulators previously built at Fermilab. First, thenew 150 kV bouncer modulator has no transformer, so the modulator circuit is simplified and the output waveform isimproved well. Second, the bouncer circuit has been changed to fit the output need, which is the most significantchallenge. This paper gives the design of the 150 kV long pulse bouncer modulator.展开更多
In order to make good use of the ability to approach any function of BP (backpropagation) network and overcome its local astringency, and also make good use of the overallsearch ability of GA (genetic algorithms), a p...In order to make good use of the ability to approach any function of BP (backpropagation) network and overcome its local astringency, and also make good use of the overallsearch ability of GA (genetic algorithms), a proposal to regulate the network's weights using bothGA and BP algorithms is suggested. An integrated network system of MGA (mended genetic algorithms)and BP algorithms has been established. The MGA-BP network's functions consist of optimizing GAperformance parameters, the network's structural parameters, performance parameters, and regulatingthe network's weights using both GA and BP algorithms. Rolling forces of 4-stand tandem cold stripmill are predicted by the MGA-BP network, and good results are obtained.展开更多
A 24 kV long pulse modulator is designed for DESY’s TESLA Test Facility (TTF). This modulator, with a 120 kV, 1.7 ms width pulse output, is used to drive a Thomson TH1801 multibeam klystron. In order to make waveform...A 24 kV long pulse modulator is designed for DESY’s TESLA Test Facility (TTF). This modulator, with a 120 kV, 1.7 ms width pulse output, is used to drive a Thomson TH1801 multibeam klystron. In order to make waveform flatness of the klystron voltage less than ±0.5%, it is necessary to use a bouncer circuit. This paper gives the Pspice simulation results of the 24 kV long pulse TESLA modulator.展开更多
In this paper,the sintering behavior of diphase β-Sialon and Al2O3/diphase β-Sialon composites has been studied and predicted by using ANN (Artificial Neural Network) method.It is found that relative density is well...In this paper,the sintering behavior of diphase β-Sialon and Al2O3/diphase β-Sialon composites has been studied and predicted by using ANN (Artificial Neural Network) method.It is found that relative density is well correlated with phase composition and sintering temperature and that the predicted values by this method are very clos to experimental results.Effectiveness of modeling has been discussed nd analyzed by presenting formulas, This may be the first attempt of applying ANN mthod in the study of refractories science and has indicated that ANN is an efficeint method.展开更多
This paper shows that exact calculation for transition probability can make some systems deviate fromFermi golden rule seriously. This paper also shows that the corresponding exact calculation of hopping rate inducedb...This paper shows that exact calculation for transition probability can make some systems deviate fromFermi golden rule seriously. This paper also shows that the corresponding exact calculation of hopping rate inducedby phonons for deuteron in Pd-D system with the many-body electron screening, proposed by Ichimaru, can explainthe experimental fact observed in Pd-D system, and predicts that perfection and low-dimension of Pd lattice are veryimportant for the phonon-induced hopping rate enhancement in Pd-D system.展开更多
It is commonly accepted that the drop in mechanical properties of INCONE1718(IN718) after long time exposure at high temperature is a result of coalescence of y", ?/ and the transformation of y" to 8-Ni3Nb p...It is commonly accepted that the drop in mechanical properties of INCONE1718(IN718) after long time exposure at high temperature is a result of coalescence of y", ?/ and the transformation of y" to 8-Ni3Nb phase. Besides the 7", ?/ and , the precipitation of B.C.C. -Cr is another factor that affects the mechanical properties of IN718. In this paper, the Thermal-Calc software is used to reveal the thermodynamic condition of -Cr formation. The calculated sections of the pseudo ternary diagrams of Cr-Nb-IN718 and Cr-Fe-IN718 explain why -Cr particles do not precipitate dispersedly in matrix but in the vicinity of phase. The selected area diffraction (SAD) of TEM confirms the crystallography relationship of -Crwith is (010) g// (-110) a.Cr, [100] s//[Hl] a-cr? In combination of TTT diagram with the Thermal-Calc and TEM results, the mechanism of -Cr formation in IN718 is suggested.展开更多
The tensile plastic deformation behavior of B2 ordered Fe 3Al single crystals at room temperature was systematically investigated. The results show that the mechanical properties are strongly orientation dependent. Th...The tensile plastic deformation behavior of B2 ordered Fe 3Al single crystals at room temperature was systematically investigated. The results show that the mechanical properties are strongly orientation dependent. The plastic elongation of crystals with orientation near is as high as 42%. Slip trace analysis shows that although slip planes are found to change among {110} , {112} and {123} with the change in orientations, the initial slip planes in all cases are {110}. Five stage work hardening curve including four linear stages and one parabolic stage is obtained; but not all stages are observed in the actual deformation of each crystal. In combination with investigations of dislocation substructure, it is found that deformations in stage Ⅰ～Ⅲ are corresponding to the motion of two fold superdislocations. The higher work hardening rate of stage Ⅱ is mainly due to the stronger interactions between primary dislocations and secondary dislocations than those in stage Ⅲ. Deformation in stage Ⅳ involved is not only the motion of two fold superdislocations but also the slip of dissociated superpartials with APB traps and the formation of APB tube, both of which are attributed to the hardening. Deformation in stage Ⅴ is controlled by the cross slip of dissociated superpartials. The dominated softening effect of cross slip reduces the hardening rate and leads to the formation of parabolic stage.展开更多
Properties of refractories affect their perfor-mance and deformation behaviour as well as their ultimate failure mode,Therefore in ordr to assess the capabilities of materials,used for refractory lin-ings,in service t...Properties of refractories affect their perfor-mance and deformation behaviour as well as their ultimate failure mode,Therefore in ordr to assess the capabilities of materials,used for refractory lin-ings,in service their properties must be evaluated.In this work the evaluation of some physical properties of calcined kaloin(Kibi,Ghana)aggregate re-fractory bodies showed an average porosity and spe-cific gravity of 24% and 2.78 respectively,An av-erage cold crushing strength of 19.6 MPa was also obtained .Thermal expansion and behaviour under a constant hot load of 196 kPa also showed good resis-tance to high temperature deformation.展开更多
A new ligand 1,4-bis(2-hydroxymethylphenyl)-1,4-dioxabutane was synthesized by reducing 1,4-bis(2-formylphenyl)-1,4-dioxabutane with NaBH4 in absolute methanol solution. The crystal structure of the title compound C16...A new ligand 1,4-bis(2-hydroxymethylphenyl)-1,4-dioxabutane was synthesized by reducing 1,4-bis(2-formylphenyl)-1,4-dioxabutane with NaBH4 in absolute methanol solution. The crystal structure of the title compound C16H18O4 has been determined by single-crystal X-ray diffraction. The ligand crystallizes in the orthorhombic system, space group Pbcn with a = 13.777(1), b = 11.731(1), c = 9.076(8) ? V = 1466.8(2) ?, Mr = 274.30, Z = 4, F(000) = 548, Dc = 1.24 g/cm3, T = 293 K, m = 8.9 cm-1 and l = 0.71073 ? The structure was refined to R = 0.0324 and wR = 0.1025 for 1112 observed reflections with I > 2s(I). The two benzene rings are not on the same plane, and the dihedral angle between them is 60.6? The ligand has C2 symmetry axis which passes through the center of C(8)C(8a). The molecules are linked to each other by hydrogen bonding network to form supramolecular chain. The ligands connect to each other through the hydrogen bonds to form one-dimensional chains which further connect through the hydrogen bonds to form two- and three-dimensional structures.展开更多
The different specimens of the Self-Baking Carbon Block are obtained by charging the baking temperature and time.The graphitizing degree G of the specimen is determined by the quantitiative X-ray diffraction.The relat...The different specimens of the Self-Baking Carbon Block are obtained by charging the baking temperature and time.The graphitizing degree G of the specimen is determined by the quantitiative X-ray diffraction.The relationships between G and temperature are expressed.The results show that the graphitizing process from amorphous carbon to graphite is apparent quasi-one-order and should be conducted above a critical temperature.1200K The transition rate increases with tenperature.展开更多
The growth of {100}-oriented CVD diamond film under two modifications ofJ-B-H model at low substrate temperatures was simulated by using a revised KMC method at atomicscale. The results were compared both in Cl-contai...The growth of {100}-oriented CVD diamond film under two modifications ofJ-B-H model at low substrate temperatures was simulated by using a revised KMC method at atomicscale. The results were compared both in Cl-containing systems and in C-H system as follows: (1)Substrate temperature can produce an important effect both on film deposition rate and on surfaceroughness; (2) Aomic Cl takes an active role for the growth of diamond film at low temperatures; (3){100}-oriented diamond film cannot deposit under single carbon insertion mechanism, which disagreeswith the predictions before; (4) The explanation of the exact role of atomic Cl is not provided inthe simulation results.展开更多
The local structures of the immiscible Fe100-xCux alloys(x=0,10,20,40,60,80and100)produced by mechanical alloying have been investigated by XAFS.For the Fe100-xCux(x≥40) solid solutions,the local structures around Fe...The local structures of the immiscible Fe100-xCux alloys(x=0,10,20,40,60,80and100)produced by mechanical alloying have been investigated by XAFS.For the Fe100-xCux(x≥40) solid solutions,the local structures around Fe atoms change from bcc structure to fcc one and the Cu atoms maintain the original coordination geometry after milling for 160 hours.On the contrary,the local structures around Cu atoms in both of Fe80Cu20 and Fe90 Cu10 alloys appear a transition from fcc to bcc structure.We found that the Debye-waller factor σof fcc Fe-Cu phase is larger than that of bcc F-Cu phase,and the σ(0.099A°)around Fe atoms is larger than that (0.089A°) of Cu in the Fe100-xCux(x≥40)solid solutions,This suggests that the mechanically alloyed Fe100-xCux supersaturated solid solution is not a homogeneous alloy,and consists of Fe-rich and Cu-rich regions for various compositions.A possible mechanism for bcc-to-fcc and fcc-to-bcc changes in Fe100-xCux solid solutions is discussed in relation to the interdiffusion and transition induced by the ball milling.展开更多
There are two tpyes of phase transformations in Fe-Mn and Fe-Mn-Si alloys when the temperature is decreased,γ(fcc)→ε(hcp) martensitic transformation(MT) and paramagnetic-antiferromagnetic transition (AMT) of γ pha...There are two tpyes of phase transformations in Fe-Mn and Fe-Mn-Si alloys when the temperature is decreased,γ(fcc)→ε(hcp) martensitic transformation(MT) and paramagnetic-antiferromagnetic transition (AMT) of γ phase.From the thermodynamic point of view,the former usually appears in a slightly higher temperature range than the latter because if is generally accepted that the magnetic tansition has a suppressing effect on the thermally induced ε martensite(Sato et al.,1984.,Bogachev and Zvigintzeva,1976;Murakami et al.,1987:Yang et al.,1992) Gartstein and Robinkin(1979) even thought that the γ-ε transformation should be terminated below Neel temperature(TN) due to the decrease of free energy arising from the AMT of γ phase.However,some experimental results hae indicated the formation of ε phase below T(Li and Wayman,1994:Fujimori.1966).In the present wert.the behavor of γ-ε transformation below TN was furtherinvestigated by clectrical resistance measurements.展开更多
The proliferation response of γδT cells to the antigen from heat-treated Mycobacterium tuberculosis H37Ra (M.tb Ag)was used as a good model in γδT cell research.From preliminary research it is found that activated...The proliferation response of γδT cells to the antigen from heat-treated Mycobacterium tuberculosis H37Ra (M.tb Ag)was used as a good model in γδT cell research.From preliminary research it is found that activated NK cells positively elevated γδT cells proliferation after simulating PBMCs with M.tb Ag.To investigate different behaviors of NK cells,γδNKT cells,γδT cells and relationships between these cell subsets,activation and proliferation of different cell subsets of PBMCs in response to M.tb Ag were analyzed.We demonstrated that NK cells,γδNKT cells and γδT cells could be activated after stimulation with M.tb Ag.γδNKT cells and γδT cells proliferated while the number of NK cells decreased after 11 day-simulation with M.tb Ag.Meanwhile,at the early time of stimulation the cytotoxicity of PBMCs was enhanced.Cellular & Molecular Immunology. 2004;1(6):467-470.展开更多
Interleukin 12(IL-12)and/or interleukin 18(IL-18)gene ablated mice were applied for the investigation of the tissue expression of interferon γ(IFN-γ).For IL-12^(-/-),IL-18^(-/-),IL-12^(-/-)/18^(-/-) and wt mice,repr...Interleukin 12(IL-12)and/or interleukin 18(IL-18)gene ablated mice were applied for the investigation of the tissue expression of interferon γ(IFN-γ).For IL-12^(-/-),IL-18^(-/-),IL-12^(-/-)/18^(-/-) and wt mice,reproductive performance were recorded and IFN-γ concentrations in heart,lung,liver,spleen,kidney and serum were quantified by ELISA. There were no significant differences of IFN-γ in heart,lung and kidney between 4 strains although control group was higher.It was observed that for IL-12^(-/-) mice,compared with other 3 groups,IFN-γ in liver and spleen were decreased(p<0.05)and reproductive performance appeared to be impaired.Serum IFN-γ level of IL-12^(-/-)/18^(-/-) mice was significantly higher(p<0.05).It was showed that IFN-γ productions under the normal condition were independent upon IL-12 and IL-18,its expressions in various tissues were different,and optimal IFN-γ is necessary for the normal growth and development of mammals.This study is helpful for clinical cytokines therapy.Cellular & Molecular Immunology.2005;2(1):68-72.展开更多
In this paper,a new measurement technique for determining thermal conductivity of semitransparent media in the temperature range 300-800 K is reported.The experimental setup is based on the step power forced transient...In this paper,a new measurement technique for determining thermal conductivity of semitransparent media in the temperature range 300-800 K is reported.The experimental setup is based on the step power forced transient hot wire technique.It is assumed that the radiative contribution to the heat transfer process arises from emission,not from absorption.In this case,application of the'thermal quadruples'method allows a very simple construction of analytical models of the experimental setup.The parameter sensitivity analysis demonstrates that the thermal conductivity of semitransparent media can be determined from the hot wire temperature response. The experimental results of a kind of glass between 300 and 800 K are presented.展开更多
Consider the regression model Y i=x τ iβ+g(t i)+ε i for i=1,…, n. Here (x i, t i) are known and nonrandom design points and ε i are i.i.d. random errors.The family of nonparametric estimates n(·) of g(·...Consider the regression model Y i=x τ iβ+g(t i)+ε i for i=1,…, n. Here (x i, t i) are known and nonrandom design points and ε i are i.i.d. random errors.The family of nonparametric estimates n(·) of g(·) including some known estimates is proposed. Based on the model Y i=x τ i+ n(t i)+ε i, the Berry-Esseen bounds of the distribution of the least-squares estimator of β are investigated.展开更多
基金funded by the Independent Innovation Project of Changjiang Institute of Survey,Planning,Design and Research Corporation (CX2020Z32)supported by the National Natural Science Foundation of China (Grant Numbers42204006 and 42104028)the Open Fund of Hubei Luojia Laboratory (Grant Numbers 230100020 and 230100019)
文摘The monument thermal effect(MTE)displacements could result in periodical signals with several mil-limeters magnitudes in the vertical and horizontal GPS position time series.However,the interaction ofvarious origins of periodic signals in GPS observations makes it difficult to isolate the millimeter-levelMTE displacement from other signals and noises.In this study,to assess the diurnal and semidiurnalsignals induced by MTE,we processed 12 very short GPS baselines(VSGB)with length<150 m.Themonument pairs for each baseline differ in their heights,horizontal structure,or base foundations.Meanwhile,two zero-baselines were also processed as the control group.Results showed that the sea-sonal signals observed in VSGB time series in the horizontal and vertical directions,were mainly inducedby seasonal MTE.Time-varying diurnal and semidiurnal signals with amplitude up to 4 mm wereobserved in the vertical direction for baselines with monument height difference(MHD)larger than10 m.Horizontal diurnal signal with an amplitude of about 2 mm was also detected for baselines withnon-axisymmetric monument structure.The orientation of the detected horizontal displacement wascoherent with the direction of daily temperature variation(DTV)driven by direct solar radiation,whichindicates that the diurnal and semidiurnal signals are likely induced by MTE.The observed high-frequency MTE displacements,if not well modeled and removed,may propagate into spurious long-term signals and bias the velocity estimation in the daily GPS time series.
基金Project supported by National Natural Science Foundation of China (50131040) and Natural Science Foundation of Inner Mon-golia (200408020706)
文摘The La-Mg-Ni-system （PuNi3-type） La2Mg （Ni0.85 Co0.15 ）9M0.1 （ M = B, Cr） hydrogen storage etectrode alloys were prepared by casting and rapid quenching. The electrochemical performances and microstructures of the as-cast and quenched alloys were determined and measured. The effects of rapid quenching on the microstructures and electrochemical properties of the alloys were investigated in detail. The obtained results show that the alloys are composed of the （La, Mg） Ni3 phase （PuNi3-type structure） and the LaNi5 phase, as well as the small amount of the LaNi2 phase. A trace of the Ni2B phase exists in the as-cast alloy containing boron, and the Ni2B phase in the alloy nearly disappears after rapid quenching. The relative amount of each phase in the alloys depends on the quenching rate. The rapid quenching technique can greatly improve the electrochemical performance of the alloy, and the effect of rapid quenching on the activation performances of the alloys is minor. Rapid quenching enhances the cycle stability of the alloy, and the cycle life of the alloy increases with the increase of the quenching rate.
文摘The 150 kV bouncer modulator is designed to drive the 10 MW multi-beam klystron for the DESYTESLA Test Facility. The modulator is different from the 10 kV modulators previously built at Fermilab. First, thenew 150 kV bouncer modulator has no transformer, so the modulator circuit is simplified and the output waveform isimproved well. Second, the bouncer circuit has been changed to fit the output need, which is the most significantchallenge. This paper gives the design of the 150 kV long pulse bouncer modulator.
文摘In order to make good use of the ability to approach any function of BP (backpropagation) network and overcome its local astringency, and also make good use of the overallsearch ability of GA (genetic algorithms), a proposal to regulate the network's weights using bothGA and BP algorithms is suggested. An integrated network system of MGA (mended genetic algorithms)and BP algorithms has been established. The MGA-BP network's functions consist of optimizing GAperformance parameters, the network's structural parameters, performance parameters, and regulatingthe network's weights using both GA and BP algorithms. Rolling forces of 4-stand tandem cold stripmill are predicted by the MGA-BP network, and good results are obtained.
文摘A 24 kV long pulse modulator is designed for DESY’s TESLA Test Facility (TTF). This modulator, with a 120 kV, 1.7 ms width pulse output, is used to drive a Thomson TH1801 multibeam klystron. In order to make waveform flatness of the klystron voltage less than ±0.5%, it is necessary to use a bouncer circuit. This paper gives the Pspice simulation results of the 24 kV long pulse TESLA modulator.
文摘In this paper,the sintering behavior of diphase β-Sialon and Al2O3/diphase β-Sialon composites has been studied and predicted by using ANN (Artificial Neural Network) method.It is found that relative density is well correlated with phase composition and sintering temperature and that the predicted values by this method are very clos to experimental results.Effectiveness of modeling has been discussed nd analyzed by presenting formulas, This may be the first attempt of applying ANN mthod in the study of refractories science and has indicated that ANN is an efficeint method.
文摘This paper shows that exact calculation for transition probability can make some systems deviate fromFermi golden rule seriously. This paper also shows that the corresponding exact calculation of hopping rate inducedby phonons for deuteron in Pd-D system with the many-body electron screening, proposed by Ichimaru, can explainthe experimental fact observed in Pd-D system, and predicts that perfection and low-dimension of Pd lattice are veryimportant for the phonon-induced hopping rate enhancement in Pd-D system.
文摘It is commonly accepted that the drop in mechanical properties of INCONE1718(IN718) after long time exposure at high temperature is a result of coalescence of y", ?/ and the transformation of y" to 8-Ni3Nb phase. Besides the 7", ?/ and , the precipitation of B.C.C. -Cr is another factor that affects the mechanical properties of IN718. In this paper, the Thermal-Calc software is used to reveal the thermodynamic condition of -Cr formation. The calculated sections of the pseudo ternary diagrams of Cr-Nb-IN718 and Cr-Fe-IN718 explain why -Cr particles do not precipitate dispersedly in matrix but in the vicinity of phase. The selected area diffraction (SAD) of TEM confirms the crystallography relationship of -Crwith is (010) g// (-110) a.Cr, [100] s//[Hl] a-cr? In combination of TTT diagram with the Thermal-Calc and TEM results, the mechanism of -Cr formation in IN718 is suggested.
文摘The tensile plastic deformation behavior of B2 ordered Fe 3Al single crystals at room temperature was systematically investigated. The results show that the mechanical properties are strongly orientation dependent. The plastic elongation of crystals with orientation near is as high as 42%. Slip trace analysis shows that although slip planes are found to change among {110} , {112} and {123} with the change in orientations, the initial slip planes in all cases are {110}. Five stage work hardening curve including four linear stages and one parabolic stage is obtained; but not all stages are observed in the actual deformation of each crystal. In combination with investigations of dislocation substructure, it is found that deformations in stage Ⅰ～Ⅲ are corresponding to the motion of two fold superdislocations. The higher work hardening rate of stage Ⅱ is mainly due to the stronger interactions between primary dislocations and secondary dislocations than those in stage Ⅲ. Deformation in stage Ⅳ involved is not only the motion of two fold superdislocations but also the slip of dissociated superpartials with APB traps and the formation of APB tube, both of which are attributed to the hardening. Deformation in stage Ⅴ is controlled by the cross slip of dissociated superpartials. The dominated softening effect of cross slip reduces the hardening rate and leads to the formation of parabolic stage.
文摘Properties of refractories affect their perfor-mance and deformation behaviour as well as their ultimate failure mode,Therefore in ordr to assess the capabilities of materials,used for refractory lin-ings,in service their properties must be evaluated.In this work the evaluation of some physical properties of calcined kaloin(Kibi,Ghana)aggregate re-fractory bodies showed an average porosity and spe-cific gravity of 24% and 2.78 respectively,An av-erage cold crushing strength of 19.6 MPa was also obtained .Thermal expansion and behaviour under a constant hot load of 196 kPa also showed good resis-tance to high temperature deformation.
基金The project was supported by the state key laboratory of Suzhou University and the foundation of Science Committee of Jiangsu Province
文摘A new ligand 1,4-bis(2-hydroxymethylphenyl)-1,4-dioxabutane was synthesized by reducing 1,4-bis(2-formylphenyl)-1,4-dioxabutane with NaBH4 in absolute methanol solution. The crystal structure of the title compound C16H18O4 has been determined by single-crystal X-ray diffraction. The ligand crystallizes in the orthorhombic system, space group Pbcn with a = 13.777(1), b = 11.731(1), c = 9.076(8) ? V = 1466.8(2) ?, Mr = 274.30, Z = 4, F(000) = 548, Dc = 1.24 g/cm3, T = 293 K, m = 8.9 cm-1 and l = 0.71073 ? The structure was refined to R = 0.0324 and wR = 0.1025 for 1112 observed reflections with I > 2s(I). The two benzene rings are not on the same plane, and the dihedral angle between them is 60.6? The ligand has C2 symmetry axis which passes through the center of C(8)C(8a). The molecules are linked to each other by hydrogen bonding network to form supramolecular chain. The ligands connect to each other through the hydrogen bonds to form one-dimensional chains which further connect through the hydrogen bonds to form two- and three-dimensional structures.
文摘The different specimens of the Self-Baking Carbon Block are obtained by charging the baking temperature and time.The graphitizing degree G of the specimen is determined by the quantitiative X-ray diffraction.The relationships between G and temperature are expressed.The results show that the graphitizing process from amorphous carbon to graphite is apparent quasi-one-order and should be conducted above a critical temperature.1200K The transition rate increases with tenperature.
基金This project was supported by National Natural Science Foundation of China (No.59872003).]
文摘The growth of {100}-oriented CVD diamond film under two modifications ofJ-B-H model at low substrate temperatures was simulated by using a revised KMC method at atomicscale. The results were compared both in Cl-containing systems and in C-H system as follows: (1)Substrate temperature can produce an important effect both on film deposition rate and on surfaceroughness; (2) Aomic Cl takes an active role for the growth of diamond film at low temperatures; (3){100}-oriented diamond film cannot deposit under single carbon insertion mechanism, which disagreeswith the predictions before; (4) The explanation of the exact role of atomic Cl is not provided inthe simulation results.
文摘The local structures of the immiscible Fe100-xCux alloys(x=0,10,20,40,60,80and100)produced by mechanical alloying have been investigated by XAFS.For the Fe100-xCux(x≥40) solid solutions,the local structures around Fe atoms change from bcc structure to fcc one and the Cu atoms maintain the original coordination geometry after milling for 160 hours.On the contrary,the local structures around Cu atoms in both of Fe80Cu20 and Fe90 Cu10 alloys appear a transition from fcc to bcc structure.We found that the Debye-waller factor σof fcc Fe-Cu phase is larger than that of bcc F-Cu phase,and the σ(0.099A°)around Fe atoms is larger than that (0.089A°) of Cu in the Fe100-xCux(x≥40)solid solutions,This suggests that the mechanically alloyed Fe100-xCux supersaturated solid solution is not a homogeneous alloy,and consists of Fe-rich and Cu-rich regions for various compositions.A possible mechanism for bcc-to-fcc and fcc-to-bcc changes in Fe100-xCux solid solutions is discussed in relation to the interdiffusion and transition induced by the ball milling.
文摘There are two tpyes of phase transformations in Fe-Mn and Fe-Mn-Si alloys when the temperature is decreased,γ(fcc)→ε(hcp) martensitic transformation(MT) and paramagnetic-antiferromagnetic transition (AMT) of γ phase.From the thermodynamic point of view,the former usually appears in a slightly higher temperature range than the latter because if is generally accepted that the magnetic tansition has a suppressing effect on the thermally induced ε martensite(Sato et al.,1984.,Bogachev and Zvigintzeva,1976;Murakami et al.,1987:Yang et al.,1992) Gartstein and Robinkin(1979) even thought that the γ-ε transformation should be terminated below Neel temperature(TN) due to the decrease of free energy arising from the AMT of γ phase.However,some experimental results hae indicated the formation of ε phase below T(Li and Wayman,1994:Fujimori.1966).In the present wert.the behavor of γ-ε transformation below TN was furtherinvestigated by clectrical resistance measurements.
文摘The proliferation response of γδT cells to the antigen from heat-treated Mycobacterium tuberculosis H37Ra (M.tb Ag)was used as a good model in γδT cell research.From preliminary research it is found that activated NK cells positively elevated γδT cells proliferation after simulating PBMCs with M.tb Ag.To investigate different behaviors of NK cells,γδNKT cells,γδT cells and relationships between these cell subsets,activation and proliferation of different cell subsets of PBMCs in response to M.tb Ag were analyzed.We demonstrated that NK cells,γδNKT cells and γδT cells could be activated after stimulation with M.tb Ag.γδNKT cells and γδT cells proliferated while the number of NK cells decreased after 11 day-simulation with M.tb Ag.Meanwhile,at the early time of stimulation the cytotoxicity of PBMCs was enhanced.Cellular & Molecular Immunology. 2004;1(6):467-470.
文摘Interleukin 12(IL-12)and/or interleukin 18(IL-18)gene ablated mice were applied for the investigation of the tissue expression of interferon γ(IFN-γ).For IL-12^(-/-),IL-18^(-/-),IL-12^(-/-)/18^(-/-) and wt mice,reproductive performance were recorded and IFN-γ concentrations in heart,lung,liver,spleen,kidney and serum were quantified by ELISA. There were no significant differences of IFN-γ in heart,lung and kidney between 4 strains although control group was higher.It was observed that for IL-12^(-/-) mice,compared with other 3 groups,IFN-γ in liver and spleen were decreased(p<0.05)and reproductive performance appeared to be impaired.Serum IFN-γ level of IL-12^(-/-)/18^(-/-) mice was significantly higher(p<0.05).It was showed that IFN-γ productions under the normal condition were independent upon IL-12 and IL-18,its expressions in various tissues were different,and optimal IFN-γ is necessary for the normal growth and development of mammals.This study is helpful for clinical cytokines therapy.Cellular & Molecular Immunology.2005;2(1):68-72.
文摘In this paper,a new measurement technique for determining thermal conductivity of semitransparent media in the temperature range 300-800 K is reported.The experimental setup is based on the step power forced transient hot wire technique.It is assumed that the radiative contribution to the heat transfer process arises from emission,not from absorption.In this case,application of the'thermal quadruples'method allows a very simple construction of analytical models of the experimental setup.The parameter sensitivity analysis demonstrates that the thermal conductivity of semitransparent media can be determined from the hot wire temperature response. The experimental results of a kind of glass between 300 and 800 K are presented.
文摘Consider the regression model Y i=x τ iβ+g(t i)+ε i for i=1,…, n. Here (x i, t i) are known and nonrandom design points and ε i are i.i.d. random errors.The family of nonparametric estimates n(·) of g(·) including some known estimates is proposed. Based on the model Y i=x τ i+ n(t i)+ε i, the Berry-Esseen bounds of the distribution of the least-squares estimator of β are investigated.
