C60 and C70 single crystals free from solvent contamination grew from their vapour. Large C60 crystals up to a size of about 5 mm×3 mm×3 mm and C70 crystals about 1 mm×1 mm×1 mm were obtained. C60 crystals with fcc structure showed two types of morphological faces, namely {111} and {100}, frequently with twinning on {111} face. C70 crystals obtained have a hcp structure witha=10.1 Å andc=16.7 Å. DSC and X-ray diffraction analysis indicated that C70 crystal underwent phase transition below 100 C. Morphological observation suggests that the growth of C60 and C70 single crystals is based on layer-spreading mechanism.
The heat effect of the reactions between metallic aluminum and NaOH(aq) solution of various concentrations were calorimetrically determined. Combining with the thermodynamic properties of related substances led to the thermodynamic properties of Al(OH)4−(aq) as following:
This paper describes the structure and function of the intelligent decision support system (IDSS) on the process of nickel matte smelter. The knowledge and model base system based on fuzzy-decision rules are specially suggested. The IDSS possesses the self-learning and adaptive properties, and has been used for managing and analyzing the production information, optimizing the composition of the charge mixture, and deciding the optimal operational conditions. Electric energy consumption has been reduced remarkably and the yield of nickel has been increased.
Experiments for investigating the problem to improve the mechanical properties of FHA [Ca10(PO4)6F(OH)] biomaterial have been presented in this paper. ZrO2 micro-particle, as strengthening phase, is added into FHA matrix material to make a composite biomaterial. Various mechanical properties were tested. Distribution behaviour of ZrO2 particle in sintered material and phase structure changes of material at elevated temperature were investigated by means of X-ray and SEM. Some biologic experiments were also carried out on animals to estimate the biological function of the composite material.
The processing of sintered brass products is described. The effect of processing parameters on the mechanical properties of the products is discussed. The relationship between the main mechanical properties and the friction and wear characteristics is analyzed. The tribological behaviour of the material is determined under different conditions (speed, load, time, environmentetc). Comparison is made with that of dense products. The friction and wear mechanisms are investigated. Results are instructive to the application of the material.
Single crystals with a size of 20 mm in diameter and 60 mm in length of Cu-Zn-Al and Cu-Al-Ni alloys were prepared by a modified Bridgeman method which involves the lowering of a cylindrical crucible with a tapered end through a temperature gradient. Theoretical analysis and experimental results both indicate that the single crystal growth rate can be benefited by a crucible with a tapered end and by a larger temperature gradient at the liquid-solid interface of the growing crystal. This study shows that there is a linear relationship between the possible maximum growth rate of the single crystal and the temperature gradient at the liquid-solid interface. Maximum growth rate is 5 mm/h when the temperature gradient is set at 3.8 K/cm. Maximum growth rate can reach up to 40 mm/h if the temperature gradient is set at 26 K/cm.
The pressure distribution on the grip zones in the CONFORM process has been analysed by means of the slab method, and from the above results the forces applied to the shoe were derived. It is shown that the pressure along the segment increases powerfully withϑ increasing in the primary grip, and increases linearly withϑ increasing in the extrusion grip. Thus, it can offer mechanics parameters for the operating techniques and CONFORM machine design.
The effects of the trace Ti on the internal friction and damping stability of Zn-22% Al eutectoid alloy has been investigated in this paper. The experimental results show that adding 0.05% Ti can improve the damping capacity and damping stability of Zn-22% Al alloy.
Antimony mercapide heat stabilizer for polyvinyl chloride is synthesized from antimony trioxide and mercaptocarboxylic acid esters, HS(CH2)nCOOi-C8H17(n=1–2) at 100–115°C in the presence of 0.5%–1% an organic acid catalyst. Some physicochemical constants of the compounds, such as density and refractive index, are determined. The complexes are hydrolabil in aqueous solutions and the bond of Sb-S is weaker than that of Sb-O. The forming bond property of antimony tris (mercaptoacid ester) has been elucidated by measurement of infrared spectra in comparison with mercapto carboxylic acid esters. The polyvinyl chloride resins containing antimony mercaptide heat stabilizers, do not darken at elevated temperatures and exhibit a high degree of stability. It is proposed that mercaptocarboxylic acid ester free radicals can esterify PVC microradicals at carbon atoms with upaired electrons.
Two kinds of biosensors for amino acids (one with nonspecific enzyme as bioelement, the other with specific enzyme(s) as bioelement), including their principles, applications, recent researches and future trends were discussed in detail. 61 references were given.
The anode refining process to remove lead and silver from crude bismuth was studied. The study was carried out with chloride melts at 400 °C in a crucible-in-crucible type pyrex glass electrolyzer. The kinetic regularity of the removal of lead and silver was found to be in accordance with the equation: lnc=b−kt. Values of constantk were determined for different current density. The relationship between the purity of refined bismuth and its direct yield was also determined. A two-stage anode refining method was established. The first stage was to remove most part of lead (about 90%) at higher current density; the second stage was used for removing silver and the remains of lead at lower current density. Under appropriate conditions high purity (wpb<0.001 %,wAg<0.004 %) of bismuth could be obtained from crude bismuth with the direct yield of bismuth up to 98%.
Interactions between the dissolved mineral species and other mineral surface were investigated using solution chemistry calculation,ζ-potential measurement, AES analysis and flotation tests. It has been indicated that there can be precipitation of scheelite over fluorite in scheelite supernatant at pH>4. The conversion of fluorite into scheelite was detected by AES. Fluorite in the supernatant of scheelite exhibits nearly identical electrokinetic property and flotation behavior with those of scheelite. The selective flotation separation of fluorite from scheelite or vice vasa may be achieved by using selective amphoteric collector for fluorite at pH<4 to avoid surface conversion.
Hydrophobicity-hydrophilicity balance relationships for self-induced and sodium sulfide-induced flotations of sulphide minerals have been established, through solvent extraction-chemical analysis of neutral sulphur (S°) on the surfaces, measurement of redox potential (Ept) of flotation pulp, and flotation tests. They may be’indicated as [S°]/[OH−] and [S°]/([OH−]+[HS−]), respectively. The neutral suphur (S°) was considered to be responsible for the hydrophobicity, the amount ([S°]) of which was controlled byEpt. The critical value of [S°] was proposed as a new concept. The hydrophilicity was contributed to OH− ion for the self-induced flotation, and to both HS− and OH− ions for the Na2S-induced flotation. At a given pH value, hydrophobicity and floatability increase with [S°]. For different pH values, a higher pH value results in stronger hydrophilicity, and hence the hydrophobicity and flotation require more [S°]. Lower pH values are in correspondence with the smaller [S°].
A Model, called “Entity-Roles” is proposed in this paper in which the world of interest is viewed as some mathematical structure. With respect to this structure, a First Order (three-valued) Logic Language is constructured. Any world to be modelled can be logically specified in this Language. The integrity constraints on the database and the deducing rules within the Database world are derived from the proper axioms of the world being modelled.
Based on an extended Gauss-Markov model where the unknown parameters has the prior normal distribution, this paper derives the maximum posterior estimate formulas of the parameters which are proved to be unbiased, efficient, and of variance of unit weight which is biased. Finally, the marginal maximum posterior estimate formula of the variance with unbiased and efficient properties is derived.
This paper describes a new technique for the roadway dust control in surface mine. In the method, the emulsified tar liquid with low concentration and the super water-absorbing resin are taken as dust adhesive and sprayed on the roadway. After doing a large number of in-situ experiments, the technique has shown its excellent characteristics on sticking dust, preventing water evaporation and reducing the combined cost of truck transportation.
In this paper, taking enterprise vitality as a target, an evaluation method of the economic development state of enterprise is proposed by using differential model. The solution of the differential model is discussed. The direct fitting methods and operational formulas for the parameters in the differential model are given. The feasible conditions of the methods are shown. It is an advantage that the methods have gotten rid of discretization error in contrast with the methods of grey theory.
This paper presents state space methods for decentralized H∞ control, which contain two respects: a parametrization approach and an iterative algorithm. For large scale systems withN subsystems, decentralized H∞ controllers can be derived by a parametrization result for centralized H∞ controllers and designed by an iterative algorithm with structured constraint to the controllers.