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1.
Structure and Magnetic Propoerty of Amorphous Fe—Ni Particles prepared by Mechanical Alloying 总被引：1，自引：0，他引：1
The amorphous Fe67.5 alloy particles have been prepared by mechanical alloying(MA) process of elemental powders.The crystallization is observed at temperature around 405℃ by means of differential thermal analyzer,It is found that the coercivity Hc and the effective magnetic anisotropy value of amorphous phase are not far from that of crystal phase.The magnetization behavior of amorphous and nanocrystalline samples prepared by mechanical alloying and milling process are quite similar,they obey 1/H law at middle-high field and 1/H^2 at higher field.The 1/H field dependence is attributed to a large number of dislocations created during MA process.The studies on the 1/H^2 field dependence reveals that magnetization of Fe-Ni ultrafine particles are governed predominantly by internal stress fields induced by MA process. 相似文献
2.
溶液凝胶自然燃烧制备的铝掺杂对钡铁氧体晶相和磁性能的影响 总被引：1，自引：0，他引：1
Al-substituted barium ferrite powders were synthesized using the sol-gel auto-combustion method according to the molecular formula BaAlxFe12-xO19 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5, 1.0). Compared with non-substituted barium ferrite annealing at 1000℃, the vibrating sample magnetometer (VSM) measurement manifested that the optimum magnetic properties formation temperature of Al-substituted barium ferrite was 1100℃. The data from X-ray diffractometer (XRD) showed that with increasing x, the lattice constants (a and c) decreased as well as the unit-cell volume Vcell. Magnetic measurement of non-substituted and Al-substituted powders annealed from 900℃ to 1200℃ exhibited that the maximum magnetization M (10 kOe), the remanent magnetization Mr and the coercivity Hc depended strongly on the chemical composition of powder as well as the annealing temperature. When annealing at 1100℃, BaAl0.5Fe11.5019 of high coercivity Hc (6584 Oe) was produced. Meanwhile, M (10 kOe) and Mr were 42.83emu/g and 25.65emu/g, respectively. 相似文献
3.
The magnetization of cobalt ferrite ferrofluid has been studied at low temperature in the presence of the carrier fluid.A prominent difference between slow and fast cooled.samples was observed.In particular the slow cooled samples display an anoamlous increses in magnetization on field reversal.The data is analyzed in terms of the possibilites of both cotherent and incoherent spin rotations. 相似文献
4.
Different cities have different climate conditions and outdoor temperature and humidity, so the scheme of an environment control in subway should be analyzed by considering objective conditions, project cost and operating status. In this paper, a physical and mathematical model is built according to the design of Shenyang subway (line 1), the boundary conditions of the model are defined by the design and experiments, the numerical analysis of ventilating scheme and air conditioning scheme is introduced individually, and the temperature field and air flow field of the two schemes are compared, so that the feasibility of using a ventilating scheme in subway of northeast cities is discussed. Considering comfort and economy, it can be concluded that mechanical ventilation is feasible in subway of northeast cities because the air temperature there is not very high in summer. 相似文献
5.
Hydantoinase and N-carbamoylase play important roles in the production of optically pure amino acids from racemic 5-monosubstituted hydantoins. In this report, hydantoinase and the N-carbamoylase from Burkholderia cepecia, njut01 were purified to homogeneity by chromatography (Pharmacia Explorer 100 system). The substrate specificity, enantioselectivity, pH dependence of activity and temperature stability of the activity were characterized. The results show that the hydantoinase and N-carbamoylase induced from Burkholderia cepecia, njut01 are both strict D-stereo selective enzymes. They both hydrolyze substrates with side chains containing aliphatic and aromatic residues with higher activity and affinity toward aromatic than aliphatic substituted substrates. The hydantoinase is a homotetramer with subtmit molecular weight near 52,000 and is active between pH 6.5 and 10 with an optimum near pH 9.0. The enzyme is active at temperatures up to 60~C, however, it appears instable at higher temperatures. The subunit molecular weight of N-carbamoylase is about 35KD. The N-carbamoylase is active in the pH range from 6.0 to 9.5. The optira-pH is 7.2 and the optinfizing bioconversion temperature of the N-carbamyolase is 52℃. 相似文献
6.
An effective-field treatment for the two dimensional Isingantiferromagent-antiferromagnetic superlattice(AFAFS)without external field is pres-ented.The critical temperature dependence of the number of laycrs of superlattice cell andthe temperature dependence of magnetization of each layer in the superlattice are investi-gated.The similarity of the magnetic properties of AFAFS and those offerromagnet-ferromagnetic superlattice(FFS)is also discussed. 相似文献
7.
Carbon encapsulated iron nanoparticles(CEINPs) with very thin shells and good core-shell structures were prepared by DC arc discharge at argon intake temperature(AIT) of 800 ℃. The results of high resolution transmission electron microscope(HRTEM), energy dispersive X-ray(EDX) spectroscope, X-ray diffraction(XRD), and X-ray photoelectron spectroscope(XPS) characterizations on the product B show that the thickness of the carbon shells of CEINPs in the product B is in the range of ca. 0.5—5.3 nm, i. e., which can be as thin as only two layers of graphite. The average diameter of the CEINPs is about 24. 7 nm. The total content of Fe element in the product B is 77.0 wt%. The saturation magnetization(Ms) and coercivity(Hc) of the product B are 107.4 emu/g and 143 Oe, respectively. The formation of the CEINPs in the product B is discussed briefly. 相似文献
8.
《浙江大学学报(A卷英文版)》2021,(2)
Pyrolysis is a cost-effective and safe method for the disposal of radioactive spent resins. In this work, the catalytic effects of V_2O_5 on the pyrolysis of cation exchange resin are investigated for the first time. The results show that it is a better catalyst than others so far studied and achieves a lowering of final pyrolysis temperature and residual rate simultaneously when aided by physical blending. The maximum reductions of the final pyrolysis temperature and the residual rate are 173 ℃ and 11.9%(in weight), respectively. Under the action of V_2O_5, low-temperature(445℃) removal of partial sulfonic acid groups occurs and the pyrolysis of the resin copolymer matrix is promoted. This is demonstrated by the analysis of pyrolysis residues at different temperatures by X-ray photoelectron spectroscopy(XPS) and element analysis. The catalytic activity of V_2O_5 is determined by effects both at acid sites and oxidation-reduction centers via H_2-TPR(temperature programmed reduction), O_2-TPD(temperature programmed desorption), CO_2-TPD, and NH_3-TPD. The catalytic effect of oxidation-reduction centers in V_2O_5 is achieved by close contact with the sulfur bond through chemisorption under the effect of acid sites. V_2O_5 is also believed to be the reason for the removal of partial sulfonic acid groups at lower temperatures(445℃). V_2O_5 is an effective catalyst for spent resin pyrolysis and can be further applied in industry. 相似文献
9.
Internal temperature is crucial to plant growth in the greenhouse. We investigated the patterns of constructing and managing greenhouses in Chongqing, and developed an algorithm of heating temperature for closed winter plastic greenhouses under the conditions of no man-made illumination, no ventilation and hot wind machine as the heating equipment, which are the most adopted pattern of greenhouses in Chongqing area. The algorithm includes two functions of temperature outside the greenhouse, which calculate the values of the warming estimation coefficient (WEC) and the gap between temperatures inside and outside the greenhouse with the measured data of outside temperature, and then give the value of internal temperature; the heat rating of heating facilities required by a greenhouse can be determined by this algorithm with given values of floor area and internal temperature, measured outside temperature and calculated WEC. Verification of the algorithm demonstrates a desirable accuracy of estimation. Algorithms of computing heating temperature for greenhouses of different constructing and managing patterns and in different geographic conditions can also be derived in a similar way. This research presents a paradigm for developing a feasible method to fit out greenhouses with appropriate heating facilities, aiming at energy efficient and cost efficient production. 相似文献
10.
A real case of a steel lattice shell suffering a fire was studied. Based on the theory of field modeling, fire dynamic simulator (FDS) was used to identify the temperature field. The damage mechanism of the structure was determined by FEM analysis. After damage assessment, the shell was repaired with the pipe-encasement method. Finally, field test was employed to check the capacity of the structure after repair. The numerical study results indicate that the damage assessment agrees well with field inspection, verifying the accuracy of fire numerical simulation and FEM analysis. The field test results prove that the pipe-encasement method is secure and reasonable, and the repaired shell is safe. 相似文献
11.
1 Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｆｅ Ｎｉａｌｌｏｙｉｓｗｉｄｅｌｙｕｓｅｄａｓｓｏｆｔｍａｇｎｅｔｉｃｍａｔｅｒｉａｌｓｆｏｒａｌｏｎｇｔｉｍｅ .Ｉｔｓｍａｇｎｅｔｉｃｐｒｏｐｅｒｔｉｅｓａｓｉｎｉｔｉａｌｐｅｒｍｅ ａｂｉｌｉｔｙμｉａｎｄｃｏｅｒｃｉｖｉｔｙｆｏｒｃｅＨｃｄｅｐｅｎｄｓｔｒｏｎｇｌｙｏｎｔｈｅｃｈｅｍｉｃａｌｃｏｍｐｏｓｉｔｉｏｎａｎｄｔｒｅａｔｍｅｎｔｌｉｋｅｑｕｅｎｃｈｉｎｇｆｒｏｍｈｉｇｈｔｅｍｐｅｒａｔｕｒｅ .Ａｓｕｌｔｒａｆｉｎｅｐａｒｔｉｃｌｅｉｓｒｅｖｅａｌｅｄｒ… 相似文献
12.
Surface morphologies of Zr52.5 Al10 Ni10 Cu15 Be12.5 bulk metallic glass after being rolled at both a temperature around T9 and near （ Tx - 50） K were investigated with a scanning electron microscopy. Macroscopic and microscopic observation results show that squamae, cracks, steps and wedges exist on the surface when the samples were rolled at temperatures around Ty. However, a smooth and fiat surface appears when the samples were rolled at temperatures near （ Tx - 50） K. These results indicate that the mode of deformation in the supercooled liquid region is a partially homogeneous flow at a temperature around T9, and a fully homogeneous one at temperatures near （ Tx - 50） K. According to the results, it is more feasible to roll the amorphous alloys at temperatures near （ Tx - 50） K to obtain parts with smooth and fiat surface. 相似文献
13.
LU Bao - qi 《上海大学学报(英文版)》2005,9(4):365-368
Infrared （IR） absorption spectra and X-ray powder diffraction （XRD） patterrns of sexpenfine cat＇s eye from Sichuan Province have been investigated, and infrared absorption bands of the serpentine have been assigned in this paper. The results indicate that the bands near 3 600 - 3 700 cm^-1 belong to the stretching absorption band VOH, the bands in 948 - 1 100 cm^-1 axe assigned to the stretching vibraling band Usvo, and the bands at 600 570 and 440 cm^-1 respectively belong to the bending vibration band VOH, δMg-O and δSi-O. The serpentine cat＇ s eye includes two types： chrysotile and antigorite. Chrysotile has a sharp and intensive band at 3 688 cm^-1 and a weak band at 3 643 cm^-1 , while antigorite has only one intensive band in the region. At vibration band VSi-O, chrysotile and antigorite have a similar feature at 1 071 cm^-1, but the band at 980 cm^-1 in anfigorite has been split into two bands in chrysotile - a strong one at 1 027 cm^-1 and a weak one at 949 cm^-1. In addition, antigorite has a characteristic bending vibrating band δMg-O at 570 cm^-1. Based on the analysis of the feature of crystal structure, their IR differences axe well explained. 相似文献
14.
1 Introduction Ahugeamountofliteratureexistsonthestudyofi dentifyingtracemetalionsbymeansofspectropho tometry[1 3] ,fluorimetry[4 6 ] aswellas polarogra phy[7 9] ,whichhaveactiononlocatingtheendpointoftheindicatingreaction .Howeverbothspectropho tometryandfluorimetryareeasytobeinterferedbycolororprecipitation ,whilepolarographyhasanissueofmercurypollution .Thecatalyzingkineticanalysishasthecharacteristicsofhighsensitivityandspeedi ness.Oscillographicpotentiometryisasimpleintu itionisticanal… 相似文献
15.
A novel nano-TiO2-xNx composite was used as photocatalyst and added to the interior wall paint. The average diameter of nano-TiO2-xNx was about 20 nm. The majority crystal component of the sample was anatase and its optical absorption edge was shifted from 387 nm to 520 nm significantly. Nano-composite paint containing different dosage of nano- TiO2-xNx was investigated to study the properties of formaldehyde decomposition in the air. Testing results show that the formaldehyde decomposition ratio of that nano-paint can almost reach above 80%, especially for that of the paint containing 3% （w/w） nano-TiO2-xNx which exceeded 90%. The primary investigation on the reaction kinetics of photocatalytic formaldehyde decomposition indicated that the experiment data well fit the model of first-order reaction kinetics. 相似文献
16.
几乎正则图的全符号控制 总被引：1，自引：2，他引：1
1IntroductionFor notation and graph theory terminology we ingeneral follow[1].LetG=(V,E)be a graph with thevertex setVand the edge setE,andletvbe a vertexinV.The open neighborhood ofvisN(v)={u∈V|uv∈E}and the closed neighborhood ofvisN[v]={v}∪N(v).The d… 相似文献
17.
In the light of Ф-mapping method and the relationship between entropy and the Euler characteristic, the intrinsic topological structure of entropy of Kerr black holes is studied. From the Ganss-Bonnet-Chem theorem, it is shown that the entropy of Kerr black hole is determined by singularities of the Killing vector field of spacetime. These singularities naturally carry topological numbers, Hopf indices and Brouwer degrees, which can also be viewed as topological quantization of entropy of Kerr black holes. Specific results S = A/4 for non-extreme Kerr black holes and S = 0 for extreme ones are calculated independently by using the above-mentioned methods. 相似文献
18.
The big upper bound of typical van der Waerden number was investigated through calculating the van der Waerden number on a circle. And the van der Waerden number Wh (3,3) = 9, Wh (3,3,3)≥25 on a circle was calculated by computer. 相似文献
19.
Let Bnp={x ∈ Rn‖|x ‖p≤l} be the unit ball ofp norm in the n-dimensional normed space p. The formula for the volume of Bnp was obtained and its asymptotic properties were found out as n→∞and p→∞. 相似文献