共查询到20条相似文献,搜索用时 15 毫秒
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《Drug development and industrial pharmacy》2013,39(7):1063-1069
Background: The evaluation of lubricity or flowability of pharmaceutical powders is important for consistent production and quality control of drug products. However, there have been only a few studies on quantitative measurements of the properties of lubricated powders.Method: Magnesium stearate (MgSt) and sodium stearyl fumarate (SSF) were used as lubricants. Lubricated powders were prepared by adding lubricants to spray-dried lactose under different conditions. To evaluate flowability, the vibrating tube method was used. In this method, the vibration amplitude of the tube is increased at a constant rate, and the mass of the powder discharged from the tube is recorded. Flowability profiles, i.e. the relationships between the mass flow rate and vibration acceleration, were obtained experimentally. To characterize static and dynamic friction properties of powders, critical vibration acceleration required to make powder particles flow and the average mass flow rate were determined.Results: Addition of 0.5% MgSt was sufficient for the reduction of static friction between particles. Blending time of the lubricants had little effect on the average mass flow rate of lubricated powders. On the other hand, addition of SSF resulted in an increase in static friction at the beginning of blending, and after a certain blending time, flowability improved. The combination of MgSt and SSF improved both static and dynamic friction properties irrespective of the blending time.Conclusion: The vibrating tube method can be used to evaluate the flowability properties of lubricated powders, and the experimental results provide useful information on the production of pharmaceutical solid dosage forms. 相似文献
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Katsunori Ishii Masahiro Suzuki Tomoomi Segawa Yoshiyuki Kihara Masatoshi Yasuda Shuji Matsusaka 《Advanced Powder Technology》2011,22(4):522-525
To reduce the sample amount required for the measurement and evaluation of particle flowability, a simple method has been developed through experimental research. The principle of this measurement is based on the vibrating tube method. The sample particles used in the experiment were pulverized ZrO2 and granulated WO3 with different concentration of fine particles. After a small amount of sample particles were put into a tube, vibration was applied at a constant frequency and amplitude, and the mass of particles discharged from the tube was measured at constant time intervals. The experimental results showed that the minimum sample amount required for the measurement to evaluate the particle flowability was 10 g. The factors to evaluate the flowability in this simple vibrating tube method were the flow time and the characteristic mass flow rate. 相似文献
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《Advanced Powder Technology》2020,31(1):351-358
Dry granulation by roll compaction is a continuum manufacturing process to produce granules with improved flowability which can further be easily used in tableting process. However, the granules are non-homogeneous in density and have non-spherical shapes which impact their densification behaviour during die-compaction. The aim of this study was to investigate both the densification mechanism and the failure strength of granules of microcrystalline cellulose (MCC) and mannitol using Cooper-Eaton and Adams models. For both materials, the Cooper-Eaton approach led to the quantification of fractional volume compaction by particle rearrangement and by plastic deformation respectively to explain the difference in densification behaviour of raw material and granules. Moreover, the model showed its ability to capture the effect of granule density and granule sizes and to differentiate the densification mechanisms of MCC as a plastic material and mannitol as a brittle material. The Adams model was used to compute the failure strength of single granule from in-die compression data. The obtained results of the granules were in the range [0.6–1.43 MPa]. However, regarding the effect of granule density, the model showed mixed results indicating that the model is not representative of the studied granules which are not spherical and have a relatively wide range of sizes, nevertheless, the model was derived for near spherical particles with a narrow size distribution. 相似文献
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M. V. Aleksandrov V. V. Malyushin V. G. Bakalov M. F. Mikhalev 《Journal of Engineering Physics and Thermophysics》1980,38(1):14-18
A method is given for determining the best pulse-fluidization conditions for accelerating the mixing of components in a granular material.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 38, No. 1, pp. 23–28, January, 1980. 相似文献
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The iron-silicon-aluminum alloys (particularly Sendust) have been widely used in applications requiring high saturation flux density, low coercive force and high electrical resistivity. For this reason they have been promising for magnetic thin film heads, however, they are too hard and brittle to be made into thin films by rolling, or into three-dimensional products of complex shape by mechanical working or a conventional powder metallurgy process. The reduction in the size and weight of devices that can be accomplished through the use of Sendust has had an important effect on technical development. In this report, magnetic characteristics of Sendust ring samples produced by the powder metallurgy process with spray drying were investigated. After gas-atomized Sendust powders were mixed with paraffin compounds, these powders were granulated by the spray drying method using organic binder consisting of polyvinyl alcohol (PVA) and plasticizer in the range from 0.1 to 0.5 wt% of PVA, in order to improve the powder flowability and mechanical strength of compacted bodies. Results show that the present method is an excellent process for producing near-net-shaped parts with high performance and high dimensional precision after sintering. 相似文献
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热扩散率是材料热物性中一个非常重要的参数。在材料热扩散率的测试中,主要是利用非稳态方法进行测量。非稳态测量方法具有测量周期短、测试方便、结果准确等优点。主要对常用的5种利用非稳态测试材料热扩散率的方法进行了阐述,详细介绍了它们的工作原理、方法特点以及近几年来的科研成果。同时,列举了目前热扩散率测试的一些常用产品和相关测试标准。最后,对热扩散率测试的未来发展趋势进行了展望。 相似文献
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Alexander R. Bogomolov Pavel T. Petrik Igor V. Dvorovenko 《Microgravity science and technology》2007,19(3-4):93-95
The heat transfer enhancement was studied during condensation of steam on a chilled vertical surface of a tube packed into a granulated material with different contact angles of wetting. The dimensionless values of heat transfer at condensation on a surface in filling, obtained for a vertical tube in the range of Reynolds numbers from 70 up to 400, exceed Nu* values for a smooth tube by the factor of 2–3. The intensification of heat transfer on a vertical tube, housed in a granulated layer, is conditioned by the several interdependent phenomena: 1 — capillary ascent of some liquid near the meniscuses, and as a consequence, reduction of the mean film thickness; 2 — burble of a film at the points of sphere contact with a surface of condensation at Re>10; 3 — removal of some film liquid by a granulated layer; accompanied by simultaneous film burble at the points of sphere contact with a cooling surface at Re>83. Results of the current research can be used for the development of heat exchanging devices under the conditions of microgravitation. 相似文献
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A simple method of measuring refractive indices of bulk materials using a prism coupling procedure is described. Refractive indices are determined from the measurement of the angle incident to the prism at which total reflection on the prism base breaks. This method is shown to possess the advantages of its simple procedure and sample preparation. The accuracy is comparable with that of minimum deviation method if the prism is well calibrated. Experimental results for several materials are given with an evaluation of possible errors. 相似文献
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Concurrent measurement of temperature and soot concentration of pulverized coal flames 总被引:7,自引:0,他引:7
Gang Lu Yong Yan Riley G. Bheemul H.C. 《IEEE transactions on instrumentation and measurement》2002,51(5):990-995
This paper presents a novel instrumentation system for the concurrent measurement of temperature and soot concentration of pulverized coal flames. The system operates on the two-color principle, combining CCD camera optical sensing and digital image processing techniques. The temperature and its distribution in a flame are calculated from the ratio between the grey-levels of corresponding pixels within two images captured at two carefully selected wavelengths. The soot concentration distribution of the flame is represented and estimated using the KL factor that is derived from intermediate information obtained during the temperature measurement. The system is calibrated using a tungsten lamp as a standard temperature source. The maximum relative error in the temperature measurement is 1.83%. Experimental results obtained on a 0.5 MW/sub th/ combustion test facility show that the temperature distribution of a coal-fired flame ranged from 1380 to 1700/spl deg/C, while the KL factor ranged from 0.18 to 0.33. 相似文献
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Single-reed musical instruments, such as the saxophone, generate sound through a complex interplay between the mechanics of the reed and the hydrodynamic and acoustic pressure in the instrument mouthpiece. To understand this complex mechanism, experimental data are lacking. This paper presents full-field, time-resolved measurements of strain and displacement of a vibrating saxophone reed, measured under mimicked realistic playing conditions. It is found that strain along the length axis of the reed is mainly expansive, except in a small zone near the tip where it becomes compressive when the reed touches the front edge of the mouthpiece. At the instant in the vibration phase where the reed touches the mouthpiece, significant bending and compressive strain appear along the direction perpendicular to the reed axis. Strain magnitudes in both directions are similar, with absolute values of 0.1%. Full-field strain maps reveal subtle characteristics which are not revealed by displacement measurements. Bi-axial bending and strain may be an essential component in reed mechanics, which up till now has been fully neglected in modelling. 相似文献
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I. L. Lyuboshits I. F. Pikus N. G. Alkhanashvili 《Journal of Engineering Physics and Thermophysics》1968,14(4):393-395
Relations derived from an experimental study of the drying of granulated sugar in a pneumatic drying tube with external heating make it possible to determine the necessary height of the tube. 相似文献
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声速和衰减是医用耦合剂的关键参数,对超声仪器的临床诊断相当重要。相关方法是测量两个相近波形之间时差的重要方法,"波形不变性"原理是相关测速的基本工作原理。基于相关方法,利用虚拟示波器在PC上构建了一个实时医用超声耦合剂测量系统。该系统通过USB接口对虚拟示波器进行控制及数据传输,并利用Windows系统的多线程工具对软件进行了优化,实现了实时测量、计算和显示。对几种耦合剂样品进行了测试,并对结果作了处理和分析,从而实现了生产过程中超声耦合剂的声速和衰减的在线检测和控制。 相似文献
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Three diamensional (3D) measurement method by Scanning Electron Microscope (SEM) has already been proposed by using the principle
of shadow moiré. In the method, the image of original grid in shadow moiré image must be clearly removed in fringe analysis
process in order to perform high resolution analysis. A new method based on the principle of projection moiré is proposed
to solve the trouble concerning the grid. In this paper, the mechanism of producing some shadows of grid on the surface of
the object by back scattering electron beam in the new method is discussed. Fringe image as shadow of grid is analyzed by
Wavelet transform. The precise 3D measurement is realized by using the phenomenon of shadows of grid. Furthermore, a 3D micro
structure on the head of a hard disk is measured. From the comparison of results obtained by Atomic Force Microscope (AFM),
it is confirmed that the proposed method has high-resolution power(about 20nm). 相似文献