A Critical Assessment of the Usp Dissolution Apparatus Suitability Test Criteria

This report describes results of a survey conducted to assess the variability in drug release from the USP calibrators and its dependence on various deaeration methods. The calibrator data submitted by 33 laboratories, involved tests of 1659 sets (6 or 12 tablets/set) from four lots of prednisone and salicylic acid each, using apparatuses 1 & 2 run at 50 and 100 rpm. Overall variabilityranges for the individual sets, which met the USP dissolution apparatus Suitability Criteria, were 0.5-31.3% for prednisone/apparatus 1, 0-13.2% for salicylic acid/apparatus 1, 0.3-10.2% for prednisone/apparatus 2 and 0.7-20.2% for salicylic acid/apparatus 2. The results of this survey suggest that variability levels are dependent on apparatus/calibrator combination. Although deaeration of dissolution media tends to reduce the failures i.e. not meeting the Suitability Criteria, its effect on reducing the variability appears to be minimal. Among the various deaeration methods reported, degassing the media by a combination of heating with helium sparging or with filtering under vacuum tend to give the lowest failure rate. From our findings, a variability of up to 31% CV (coefficient of variation) in percent drug release for the calibrator can occur with the samples still meeting the USP criteria. However, if the apparatus/calibrator combination is taken into consideration with appropriate deaeration method, the maximum expected variability can be reduced to 10% or less. The results of this survey show that rather than an eight point dissolution calibration test criteria, a four point evaluation system i.e. testing non-disintegrating tablets with apparatus 1 and disintegrating tablets with apparatus 2 may provide sufficient information for system suitability. It is also recommended that a similar formulation/apparatus combination should be considered for drug products evaluation which might yield less variable results with an improved potentials of in vitro/in vivo correlations particularly for modifieddrug release products.     

Kalibrierdruckerzeugung durch statische Gasexpansion

The method of generating well known calibration pressures by means of static expansion of gases is described and the required mathematical equations are derived in general form for real gases. Temperature effects caused by the expansion process are estimated and compared with experimental data obtained at an expansion apparatus. Thereafter, the experimental measurement of the expansion ratio and the generation of calibration pressures over a wide pressure range are discussed for a specific apparatus. Controlling the temperature by immersing the apparatus in a circulated water bath, the uncertainty contribution due to temperature effects was substantially reduced as compared to conventional apparatuses. The uncertainty budget reveals that this apparatus allows the generation of a pressure of, e.g., 0.1 mbar for various gases with a small relative uncertainty (2σ) of 1 . 10^‐3.     

CO2局部腐蚀测试及评价方法

局部腐蚀测试及评价一直是困扰腐蚀界的一大难题.针对CO2局部腐蚀的特征,研发了一种测量CO2局部腐蚀的测试仪.它能准确测定局部腐蚀的有关几何参数,定量评定局部腐蚀的破坏程度,并根据CO2局部腐蚀的特征,建立一种评定CO2局部腐蚀的方法.     

基于数字图像相关技术的砂土全场变形测量及其DEM数值模拟

岩土材料在力学性能上表现出各向异性与非线性特征,不同土体的受力变形规律也不相同。为了更真实地反映平面应变状态下土的受力变形特性,研制了一种新型的平面应变加载设备,该设备通过对试样的侧向（围压方向上）施加柔性荷载来降低常规平面应变试验中刚性加载所造成的边界约束影响。同时,搭建了能够得到表面变形识别的数字图像采集系统。在此基础上,利用研制的平面应变设备结合二维数字图像相关技术（2D-DIC）根据获得试验过程中的全场变形来分析福建标准砂在不同围压下的变形特性。另外,通过数字图像相关法得到的平面应变试验结果来确定砂土基于抗滚动摩擦模型的细观参数,并对试验过程进行了离散元分析。结果表明:基于数字图像相关测量技术的新型平面应变试验设备可以准确获得福建标准砂的局部变形规律和变形过程的非线性行为,由此确定的砂土细观参数也能够较为真实地反映试验材料的应力-应变关系。     

超临界反溶剂过程制备乙基纤维素超细微粒

超临界反溶剂过程是近年来提出的一种制备纳微米粉体材料的新方法.文中利用超临界反溶剂过程制备乙基纤维素超细微粒.实验以乙醇为有机溶剂,超临界CO2为反溶剂,研究了操作压力、温度、溶液浓度、反溶剂流量等操作参数对制备的超细微粒的形态、粒径及其分布的影响.研究表明,采用乙醇作为有机溶剂可得到较理想的结果,能制备出平均直径在20 nm～40 nm范围内的乙基纤维素超细微粒.通过傅立叶红外光谱分析了乙基纤维素超细微粒结构,从特征基判断其结构未发生变化.     

A modified Auger system for Auger electron appearance potential spectroscopy

We present an apparatus for Auger electron appearance potential spectroscopy measurements derived from a conventional Auger electron spectrometer. This non-dispersive apparatus is shown to be very sensitive with a high spatial resolution. The utility of the technique has been tested by measuring the 2P levels for some 3d transition metals.     

A new testing method to obtain mode II fatigue crack growth characteristics of hard materials

Flaking type failure in rolling‐contact processes is usually attributed to fatigue‐induced subsurface shearing stress caused by the contact loading. Assuming such crack growth is due to mode II loading and that mode I growth is suppressed due to the compressive stress field arising from the contact stress, we developed a new testing apparatus for mode II fatigue crack growth. Although the apparatus is, as a former apparatus was, based on the principle that the static K_I mode and the compressive stress parallel to the pre‐crack are superimposed on the mode II loading system, we employ direct loading in the new apparatus. Instead of the simple four‐point‐shear‐loading system used in the former apparatus, a new device for the application of a compressive stress parallel to the pre‐crack has been developed. Due to these alterations, mode II cyclic loading tests for hard steels have become possible for arbitrary stress ratios, including fully reversed loading (R=?1); which is the case of rolling‐contact fatigue. The test results obtained using the newly developed apparatus on specimens made from bearing steel SUJ2 and also a 0.75% carbon steel, are shown.     

Controlled growth of CsI〈Tl〉 single crystals

CsI〈Tl〉 crystals have been grown by the axial-heat-flux-close-to-the-phase-interface (AHP) method in a purpose-designed apparatus at an argon overpressure. The furnace and crystallizer of the apparatus have been designed to ensure considerable (5 to 100 K/cm) axial and low (within 1 K/cm) radial temperature gradients at the growth interface. The effects of the melt layer thickness, temperature gradient, and activator concentration in the melt on the crystal quality have been studied. The results demonstrate that reducing the AHP heater temperature for even a short time (by 2°C in 3 min) markedly raises the actual growth rate, from 2 to 15 mm/h, and leads to entrapment of bubbles of various diameters and TlI inclusions.     

材料在真空环境下放气的测试技术研究

往真空材料放气率测试装置上对金属材料的放气特性进行了实验研究,实验采用的方法为静态升压法、固定流导法、双通道气路转换法。实验结果表明,测试装置的极限真空度为9．2×10^-9Pa,铜、铝合金2A12、304不锈钢三种材料半小时后的放气率分别为2．34×10^-8a·m^3·s^-1·cm^-2、1．83×10^-9Pa·m^3·s^-1·cm^-2、8．48×10^-11Pa·m^3·s^-1·cm^-2。利用四极质谱计测得装置的本底气体成分主要有H2、N2／CO、H2O和CO2,材料放出的气体成分主要有N2／CO、H2O。三种方法测试得到的铜金属材料的放气率随着温度的升高而小断增大。     

A high-accuracy dilatometer for the range −20 to 700°C

We have constructed a linear-thermal expansion apparatus that employs a potassium-loaded heat pipe to provide a homogeneous temperature environment for the sample and utilizes the Merritt-Saunders (optical interferometric) method of observing its expansion. The apparatus is similar in many respects to one described previously. Temperature regulation and measurement are accomplished through the use of a dedicated laboratory microcomputer operating with a simple program. Two platinum resistance thermometers, read automatically by a digital resistance bridge, provide, on command, both the temperature of the heat pipe and that of the sample chamber. Changes in sample length are determined from measurements of the corresponding changes of optical fringes from a Fizeau interferometer as recorded on film. The coefficients of thermal expansion of two Pt-Rh alloy samples determined using the present apparatus agree at the±2 ppm level with those determined for a similar sample using the previous apparatus.Paper presented at the Tenth International Thermal Expansion Symposium, June 6–7, 1989, Boulder, Colorado, U.S.A.     

Pirani真空变送器的校准

通过对Pirani真空变送器的测量和校准,分析Pirani真空变送器输出信号和真空度之间的函数关系.由输出信号示值误差与真空度示值相对误差之间的关系,建立Pirani真空变送器的校准装置,并对某类型的Pirani真空变送器进行了测量,测量结果扩展不确定度U=0.046V (k=2),对应于真空度示值相对误差δ不大于±1...     

Specific Heat Measurement of High Temperature Thermal Insulations by Drop Calorimeter Method

By applying the drop calorimeter method, a specific heat measuring apparatus that can be used in the temperature range from 100 to 1000°C has been developed. It is generally difficult to measure the specific heat of thermal insulation, because the insulation material is porous, and has low thermal conductivity and small heat capacity. In the present apparatus, the specific heat of thermal insulation is simply measured by dropping a heated specimen into water. The specific heat of the specimen obtained by the apparatus is the mean specific heat between the initial specimen temperature before dropping and the equilibrium water temperature after dropping. This apparatus was used to measure the mean specific heat of standard specimen SRM 720 Synthetic Sapphire (-Al₂O₃) whose reference values are certified by the National Institute of Standards and Technology (NIST). The measured values agreed well with the reference values within an error of ±10%. The specific heats of SiC refractory material, rock wool, alumina silica fiber, alumina silica board, calcium silicate, and SiO₂ glass measured with this apparatus are also presented.     

An apparatus for accurate determinations of vapour-liquid equilibrium properties and gas PVT properties

A precision apparatus for the experimental determination of vapour-liquid equilibrium properties and PVT properties of gas mixtures has been constructed and thoroughly tested. The apparatus used in the phase equilibrium determinations is of the vapour recirculation type, and that used in the PVT measurements is a Burnett apparatus.The experiments may be performed in the temperature range ?180 to +25°C, the temperature being controlled to the nearest ±0.01°C. The temperature can be measured to the nearest 0.01 K using a high precision ac bridge and a calibrated resistance thermometer. The pressure range is from 3 to 350 atm (1 atm = 101.3 kN m^?2) on the vapour recirculation apparatus and up to 700 atm on the Burnett apparatus; the pressure is determined with a dead weight piston gauge, which has an accuracy of 0.01% of the reading or 0.005 lb in^?2, whichever is the greatest. The composition of the gas and liquid phases is determined using a carefully calibrated gas chromotograph. Both the gas and the liquid samples are injected directly into the carrier gas of the gas chromatograph.     

Development of an Apparatus for the Determination of Spectral Reflectivity at High Temperatures in the Visible

The paper presents a reflectometer for high temperature measurements. In this apparatus, the directional-hemispherical spectral reflectivity is measured by comparing the optical response of the sample to white light with the response of a reference material. The reflected light, collected by an integrating sphere, is dispersed in a spectrograph and detected by an ICCD camera. This procedure allows the simultaneous measurement of the reflectivity in a large, continuous wavelength range (presently 510 to 860 nm). An electrical resistance heater is used to heat the samples up to about 1200 K; for higher temperatures a flash-lamp pumped dye laser is used. To avoid laser induced plasma generation, the integrating sphere is placed inside a vacuum chamber, which also allows measurements under a controlled atmosphere. The response of the apparatus is calibrated to an absolute scale which allows the determination of the sample temperature by fitting the thermal emission spectrum with Planck's formula. To check the performance of the apparatus, measurements on Fe₂O₃ (hematite) and NiO have been carried out.     

Mass transfer in a rotor dispersion-film apparatus

Results of experimental investigations of the desorption of carbon dioxide from water in a rotor dispersion-film apparatus are presented. The main factors influencing the volume mass-transfer coefficient in the liquid phase and the efficiency of mass transfer in this apparatus were determined. A comparative analysis of the apparatus investigated with other analogous apparatus has been carried out. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 2, pp. 144–148, March–April, 2007.     

Granularity in ion-beam-sputtered TiO(2) films

TiO(2)-SiO(2) multilayer dielectric stacks that were deposited by ion-beam sputtering were found to have a granular structure. The grains were in the TiO(2) layers rather than in the SiO(2) layers. Their formation was due to the heating of the film during deposition. When the apparatus was modified to reduce the substrate temperature, the granularity was eliminated.     

An apparatus for measuring infra-low-frequency noise

Conclusion Using the apparatus developed by the authors, a series of measurements was carried out of the noise factor of prototypes of MOS transistors with an induced p-channel which were fabricated in the technological laboratory of the microelectronics chair of the Moscow Engineering Physics Institute.The apparatus described allows measurement of the spectral density of the noise (or the noise factor) by the comparison method in the frequency range from 0.1 to 100 Hz. The effective filter passband varies in the range from 10 to 100% of the resonant frequency. The sensitivity of the apparatus was determined by the sensitivity of the broadband amplifier used, and in our experiments it was 0.1V²/Hz.The measurement error, which is determined by the error of each of the blocks of the apparatus, does not exceed 15%.Translated from Izmeritel'naya Tekhnika, No. 8, pp. 74–76, August, 1970.     

Absorption of carbon dioxide by raw and treated dye-bath effluents

A bench-scale experimental apparatus, consisting of a glass column randomly packed with cylindrical glass rings, was utilized for the removal of carbon dioxide (CO(2)) by chemical absorption. Various liquid solvents were used, in a batch mode, circulating between the column and a reservoir vessel, and contacting the gas in counter current flow. The absorptive capacity of the liquid solvents and the absorption kinetics were studied by obtaining the respective 'breakthrough curves'. Aqueous solutions of sodium hydroxide (NaOH) were initially utilized in order to demonstrate the experimental apparatus function. Dye-bath effluent proved highly effective due to its high alkalinity and the capacity of the hydrolyzed "azo-reactive" dyes to react with CO(2). Decolorized dye-bath effluent (treated with FeSO(4)) can also be used as a chemical solvent for the absorption of CO(2); however, its absorptive capacity is much lower compared to the raw wastewater. The above technique is also a very effective method to neutralize industrial effluents.     

New equipment for checking heat-power instruments

Summary The first specimens of the described apparatus were produced by the Etalon Plant of the VNIIM in high-temperature performance, and they were thoroughly tested. Thanks to their compactness, convenience in operation, and high checking accuracy, the apparatuses will undoubtedly find a wide application in the laboratories of the Committee system and in control laboratories of metallurgical plants.The process of testing with both apparatuses is considerably speeded up thanks to a rational selection and arrangement of standard measuring instruments built into the apparatus, switching and regulating devices, and also thanks to the application of the semi-automatic standard R2-A potentiometer ZIP model.According to sources in literature, an apparatus for testing secondary instruments has not been developed abroad.The drawings of the apparatus are presently being handed over to a number of organizations in order to bring about its production in series.     

Digital Ventilated Psychrometer

A digital ventilated psychrometer for direct reading of the relative humidity (RH) from the digital indicator by means of two identical type thermistors is described. The method is based on the temperature to linear voltage converter, the calculator of the dry and wet bulb temperature ratio, the converter from the ratio to the voltage proportional to RH, and the analog to digital (A/D) converter. The experimental result by the digital ventilated psychrometer shows that the apparatus makes the direct indication of RH possible. The accuracy of the apparatus is estimated to contain an RH error of less than 2 percent and it is almost the same as that of the Assmann psychrometer. The principal advantage of the apparatus is the direct indication of RH and the capability to use the data directly for the input of the digital data processor.