Drying of suspensions and solutions on inert particle surface in mechanically spouted bed dryer

To eliminate some disadvantages of the conventional spouted bed dryers the mechanically spouted bed （MSB） system was developed. This dryer type is convenient to use inert particles providing an increased surface area for drying of materials of high-moisture content and heat sensitive materials. On three different drying tasks are demonstrated the experimental optimization of process parameters to obtain products of demanded quality. The main object was at drying of AIO（OH） suspension to preserve the particle size under 2.5μm and to obtain product with a moisture content of about 0.05 kg/kg （d.b.）. For this reason a very thin particle coating and intensive abrasion had to be assured. At drying of tomato concentrates the thermoplasticity makes the process very difficult. To jump over the deliquescent and sticky state developed at the critical temperature-moisture content values a very short drying time （8-10 s） must be provided. The third task was to form powder-like product from bovine serum albumin （BSA） solution having very low solid content （2-4%）. The selected process parameters given in this paper resulted in a mean particle size of less than 20 μm while the soluble oreserved orotein content was higher than 90%.     

Effects of electrically inert fillers on the properties of poly(<Emphasis Type="Italic">m</Emphasis>-xylene adipamide)/multiwalled carbon nanotube composites

The effects of three types of electrically-inert fillers, calcium carbonate (CaCO₃), talc and glass fiber (GF), on electrical resistivity, crystallization behavior and dynamic mechanical properties of poly(m-xylene adipamide) (MXD6)/multiwalled carbon nanotube (MWCNT) composites are investigated. The electrical resistivity of MXD6/MWCNT composites is significantly reduced with the addition of inert fillers due to the volume-exclusion effect that leads to increased effective concentration of MWCNTs in MXD6 matrix and also due to improved MWCNT dispersion. The crystallization temperature of MXD6 increases with the addition of MWCNTs, indicating that MWCNTs can act as nucleating agent and induce crystallization of MXD6. The incorporation of inert fillers has no further effect on crystallization behavior of MXD6, but significantly improves the storage modulus of MXD6/MWCNT composite, demonstrating that CaCO₃, talc and GF filled MXD6/MWCNT composites are very promising materials with not only improved electrical property but also excellent mechanical properties.     

惰气熔融红外吸收法测定高纯金中痕量氧

在采用全杂质元素扣除法进行纯度计算时,痕量氧对高纯金的纯度测定具有明显影响,而以往的杂质扣除法不计算氧等非金属元素,使得纯度测定结果缺乏说服力.通过建立惰气熔融红外吸收法,测量高纯金纯度标准物质中痕量氧含量,同时采用二次离子质谱法进行了方法比对,确保测量结果的可靠性.优化了氧氮氢分析仪的测量参数,确定了最佳工作条件:吹...     

Interaction of detonation with inert gas zone

The results of experimental study on detonation interaction with the regions of low reactivity, generated by the injection of an inert gas into reactive mixture, are reported. A square cross-section 60×60 mm, 3.6 m long detonation channel was used. The experiments were done for stoichiometric H₂−O₂ mixture at 0.3 bar and 0.5 bar initial pressure and room temperature. The inert gas (Ar, He, N₂ or CO₂) was injected from 0.523 dm³ container into the main channel 1 s before ignition. The size of the inert zone was controlled by inert initial pressure. The behavior of detonation was studied using direct streak photography and pressure transducers. The study has shown that at low pressure of Ar, N₂ and CO₂ injection only a slight decrease of detonation velocity occurs. At higher injection pressures complete damping of detonation and flame extinguishment occur, followed by flame reigniton and DDT outside the inert zone. For low He injection pressures an increase in detonation velocity was recorded. For higher injection pressures, detonation damping occurred, followed by DDT process. The results have shown that CO₂ has the strongest effect on damping 2H₂+O₂ detonation, with N₂ and Ar in the next places, and He very far behind. The effectiveness of inert gas in detonation damping was found proportional to its molecular weight and reciprocal to its specific heat ratio. The numerical simulations of detonation propagation through inert gas zone were also performed using the one- dimensional Detonation Lagrangean code with simple energy release model. The results of simulations are in good qualitative agreement with experimental tendencies. In particular, the model has shown that the re-initiation of detonation is enhanced by smooth concentration gradients at inert/reactive interface. An abridged version of this paper was presented at the 15th Int. Colloquium on the Dynamics of Explosions and Reactive Systems at Boulder, Colorado, from July 30 to August 4, 1995     

Numerical solution scheme for inert,disperse, and dilute gas-particle flows

A multi-velocity formulation is proposed for the solution of an Eulerian representation of an inert, disperse, and dilute particle-phase of a gas-particle flow. Single-velocity formulations are capable of predicting regions of zero particle concentration but are problematic with crossing particle trajectories or compression waves. The multi-velocity formulation described here can account for crossing particle trajectories by splitting the particle-phase into distinct velocity families which are transported separately in the flow. Switching of the particle families at solid boundaries and due to momentum transfer with the gas-phase is conducted in a manner that enforces conservation of mass, momentum, and energy. This numerical method is combined with a parallel block-based adaptive mesh refinement algorithm that is very effective in treating problems with disparate length scales. The block-based data structure lends itself naturally to domain decomposition and thereby enables efficient and scalable implementations of the algorithm on distributed-memory multi-processor architectures. Numerical results are described to demonstrate the capabilities of the approach for predicting gas-particle flows.     

Intra-cluster exchange-coupled high-performance permanent magnets

Inert gas condensation has been used to produce Fe-rich Fe–Pt clusters imbedded in C or SiO₂. Compositions of the clusters ranged from the single-phase Fe₃Pt phase field to the single-phase FePt phase field, and included compositions in the two-phase Fe₃Pt+FePt phase field. The as-formed clusters formed in the A1 fcc structure for all compositions, and after proper heat treatment transformed to the Fe₃Pt and/or FePt phases, depending on composition. Because the clusters were well isolated, the scale of the phases was limited by the cluster size. This intracluster structuring on such a fine scale ensured that the soft Fe₃Pt and hard FePt phases were fully magnetically exchange-coupled with each other, which allowed greater soft phase fractions comparing with previous work. Energy products of the two-phase clusters with 50% Fe₃Pt exceeded 25 MGOe, compared to 11.8 MGOe for the single-phase FePt clusters. Micromagnetic simulations revealed remarkable similarities with the experimental results with respect to the relationship between both coercivity and energy product as a function of cluster composition.     

Generalisation of a property of Hamiltonians depending linearly upon a parameter: application to a model of inert gas matrix effect on vibrational spectra

The property that the ground state eigenvalue of a Hamiltonian, depending linearly upon a parameter, is a concave function of this parameter is generalised. It is shown that the concavity or convexity of the nth eigenvalue depends upon the relative weights of the states below the nth state, with respect to those above it, in a weighted sum of transition energies. The result is illustrated on a model of matrix effect on gas phase molecular vibrational spectra. The model is applied to the 2,3-naphthyne molecule.     

The combustion synthesis of iron group metal fine powders

The new approach has been developed for the synthesis of nickel (Ni), cobalt (Co) and iron (Fe) powders from the appropriate oxides by the solid combustion method. The reduction was made by sodium azide (NaN₃) at the presence of carbon in the argon atmosphere. The variation of combustion temperature and velocity was performed by using alkali metal salt as an inert diluent. The values of combustion parameters were measured and also the temperature distribution in a combustion wave are obtained. The geometric sizes of reactionary zones and the activation energy of the process were estimated. The optimum conditions for single-phase metal powder synthesis were found. Powders fabricated in this way had cubic structure and particles size about 0.5-2.0 μm for Ni, Co and 1-3 μm for Fe. In a number of cases the formation of spherical particles with the average size about 5-15 μm were observed.     

Oxygen-evolving SnOz-based Ceramic Anodes in Aluminium Electrolysis

This study deals with SnO2-based ceramic anodes doped with Sb203 and CuO, aiming at contributing new data regarding their electrochemical behavior in cryolite melts. The performances of the anodes were evaluated by anodic polarization, cyclic voltammetry, and current efficiency and corrosion measurements. The investigation proves that the anodic process of SnO2-based inert anodes occurs at a low overvoltage and the oxygen discharge takes place in one step with an exchange of two electrons. The current efficiency and corrosion were proved to be dependent on the electrolysis parameters and composition of electrolysis bath. For a long term electrolysis, the dissolution of the anode in the cryolite-alumina melt produced small aluminium contamination（ca. 0.2%, mass fraction）.     

Preparation of inert glass capillary columns coated with UCON 50 HB-5100. An attempt to rediscover industrially produced α, ω-polyethylene/polypropyleneglycol ethers as stationary phases in capillary gas chromatography

Using UCON 50 HB-5100, one of the most successful stationary phases in capillary gas chromatography during the past decade, as an example, we wish to redirect attention to the excellent properties of the polyethylene/polypropyleneglycol ether copolymer coatings. Based on experience gained in work with OH-terminated polysiloxanes, a method is described for preparing inert and relatively temperature stable chemically bonded and crosslinked coatings in a single working step. Methyltrimethoxysilane was used as coupling agent, and trifluoroacetic acid was introduced as an acidic catalyst. The reaction mechanisms involved as well as the influence of additional crosslinking on the column behavior are discussed, particularly with respect of the inertness of the coatings.