Comparison of two paddle wheel geometries within the filling chamber of a rotary tablet press feed frame with regard to the distribution behavior of a model powder and the influence on the resulting tablet mass

Objective: The purpose of this study was to compare the influence of two different paddle wheel geometries on the distribution behavior of a model powder within the filling chamber of the modified feed frame of a rotary tablet press. Moreover, both paddle wheels were compared regarding their influence on the resulting tablet mass during the tableting process.

Significance: Insights are provided regarding the influence of the paddle wheel geometry on the powder distribution to optimize the die filling process.

Materials and methods: Avicel PH 102 served as model powder. A laser triangulator was used to scan the powder surface level within the feed frame and, combined with the determination of the angle position of the paddle wheel, an in-house written software was used to calculate the powder surface profiles and filling levels. Two experimental setups, one based on the filling chamber filled with a defined amount of powder (offline) and one using the filling chamber during tableting (inline) were applied.

Results: Both paddle wheel geometries caused a significantly different distribution behavior of the powder within the filling chamber. The tablets obtained with the round rod filling wheel showed significantly higher tablet masses and significantly lower standard deviations. The inflow of powder into the filling chamber appeared to be improved with the round rod filling wheel.

Conclusions: Under the applied experimental conditions, the round rod filling wheel showed obvious advantages compared to that with flat rods in terms of the uniformity of tablet masses and the extent of die filling.     

Non-Aqueous Emulsions as Vehicles for Capsule Fillings

Abstract

New vehicles were developed based on non-aqueous emulsions. They may be classified as progress or supplimentation to the actual respectively conventional filling masses for soft gelatin capsules, but also for liquid or semi-solid hard gelatin capsule filling techniques.

IN-VITRO dissolution rate studies exhibit a clear superiority of PEG filling masses about oil-wax bases, which show extremely slow release rates.

These experiencies may therefore open an interesting way of attaining better bioavailabilities in certain cases with soft gelatin capsules as well as with hard gelatin capsules.

But in the following corresponding IN-VIVO tests, which are carried out as urine recoveries, the whole loss of superiority of the PEG compounds is impressingly shown. On the contrary the PEG bases exhibit IN-VIVO the lowest recoveries, while the non-aqueous emulsions at least those with the Riboflavin indicate a tendency towards a more favorable gastrointestinal absorption.     

Squeezing of Bound Solitary Waves in a Birefringent Optical Fibre

Abstract

The coupled nonlinear Schrödinger equations in a birefringent optical fibre are derived by means of the method of path integrals. The dependence of the squeezing effect on the coupled waves is obtained with a first-order perturbation approximation, considering zero-dispersion, normal and abnormal dispersion.     

Forty-Sixth Annual Exhibition of the Institute of Physics and the Physical Society

Abstract

The frequency histogram of connected elements (FHCE) is a recently proposed algorithm that has successfully been applied in various medical image segmentation tasks. The FHCE is based on the idea that most pixels belong to the same class as their neighbouring pixels. However, the FHCE performance relies to a great extent on the optimal selection of a threshold parameter. Since evaluating segmentation results is a highly subjective process, a collection of threshold values must typically be examined. No algorithm has been proposed to automate the determination of the threshold parameter value of the FHCE. This study presents a method based on the fuzzy C-means clustering algorithm, designed to automatically generate optimal threshold values for the FHCE. This new approach was applied as a part of a structured sequence of image processing steps in order to facilitate segmentation of microcalcifications in digitized mammograms. A unique threshold value was generated for each mammogram, taking into account the different grey-level patterns based on different compositions of various breast tissues in it. The segmentation algorithm was tested on 100 mammograms (50 collected from the Mammographic Image Analysis Society and 50 normal mammograms onto which a number of simulated microcalcifications were generated). The algorithm was able to detect subtle microcalcifications with sensitivity ranging from 93 to 98%, False alarm ratio from 3 to 5% and false negatives variability from 2 to 3%.     

Microstructure evolution of friction welded dissimilar joint during subsequent hot work

Abstract

The present paper reports the influence of hot working conditions on the microstructure of Ti₂AlNb/TC11 dissimilar joint. Linear friction welding technique was used to fabricate the joints. The microhardness and tensile properties of the joints have been tested. It was found that the fine structure of linear friction welds underwent abnormal grain growth and abnormal grain boundary phase growth in the post-weld solution heat treated condition. This phenomenon significantly deteriorated the ductility of the joint. After appropriate hot work, abnormal big grains/phases disappeared, and the joint exhibited good tensile properties due to its fine structures.     

All-Carbon [60]Fullerene Oligomers of Pearl-Necklace Type

Abstract

The formation of all-carbon [60]fullerene derivatives was observed in the course of the thermolysis of methano-fullerene derivatives. IR, UV-Vis, GPC, ¹³C-NMR, TG-MS, TOF-MS and STM data are consistent with the formation of all-carbon [60]fullerene oligomers without a direct connection between fullerene cages but through one or two carbon atoms as bridges. Molecular masses up to 8000 amu have been detected by mass spectroscopy.     

Hydrogen isotope and3He impurities in liquid4He

Recently Reynolds, Hayden and Hardy(J. Low Temp. Phys. 84,87 (1991)) analyzed atomic deuterium lifetimes in a cell with walls covered by a saturated⁴He film. They were able to determine the deuterium chemical potential in⁴He and also discussed the possibility of estimating its effective mass. These measurements inspired our attempt to understand the properties of hydrogen isotope impurities in liquid⁴He using the extended Jastrow-Feenberg theory based on the correlated wave function. We present results for hydrogen isotope chemical potentials in the bulk⁴He as a function of density. The accuracy of the method is tested by calculating the chemical potential of the³He impurity. We find a good agreement with existing measurements. We also calculate the effective masses of the hydrogen impurities. For deuterium we predict a value,m _eff=4m _D .     

MEASUREMENT OF THE KINETICS OF SOLUTION DROPLETS IN A CONTINUOUSLY MIXED CHAMBER

ABSTRACT

An experimental system is designed for the measurement of the evaporation and growth kinetics of individual solution droplets. Electrostatically charged droplets, nominally tens of micrometers in diameter, are suspended in a hyperboloidal electrodynamic chamber by balancing the droplet ueight against a uniform electrostatic field. By controlling the mixing dynamics in the chamber with specific flow configurations, a continuously mixed chamber is achieved. Consequently the Instantaneous chamber relative humidity is predicted from an exponential law with o characteristic relaxation time which is given by the ratio of the chamber volume and the gas volumetric flow rate. The evaporation and growth kinetics of phosphoric acid droplets is measured for relative humidity changes between 30 and 80%. Comparison between experimental and theoretical instantaneous droplet masses reveals less than a 5% deviation.The present system is employed to analyze the effect of adsorbed hexadecanol surfactant molecules on the evaporation and growth kinetics of phosphoric acid droplets. It is found a critical coverage exists which will result in a dramatic reduction in the evaporation kinetics of solution droplets. ConcomiCantly, the condensation coefficient is reduced from unity to 4.0 x 10-5 as droplet kinetics occur in the presence of a complete monolayer of hexadecanol.     

On the geometric factors in fractured media

Abstract

In double‐porosity and multiple continuum models the fractured rock domain can be simplified as two overlapping continua, one for the matrix block system and the other for the fracture network. In this case, it is necessary to define an exchange term accounting for the transfer of fluid and solute masses between the two continua. A newly derived geometric parameter appears in the fluid exchange term, and is valid for any point‐centered block. The geometric parameter is more general and has a clear physical meaning. It is a function of both the shape and the size of the matrix block and agrees well with the double porosity model. The geometric center and conductance of the element is different under the quasi‐steady state compared to the steady state. Quasi‐steady condition is more suitable than steady state condition for modeling fractured media.     

Effect of presence of SiC and operating frequency on the damping behaviour of pure magnesium

Abstract

The objective of the present work was to investigate the effect of presence of SiC reinforcement and the vibration frequency on the overall damping characteristics of pure magnesium. The testing method uses a combination of the modified free – free beam method coupled with a circle fit approach. The effect of frequency on the damping property was studied by adding end masses to the specimen so as to alter the resonant frequency of the suspended beam. In the present study, the results are compared against a monolithic magnesium sample. The results revealed a higher damping capability of the composite specimen at all tested frequencies when compared to monolithic magnesium. Both monolithic and reinforced magnesium showed a progressive decrease in damping with an increase in frequency. An attempt is made to rationalise the damping behaviour of the composite in terms of the presence of a process induced plastic zone at the matrix/particulate interface and the operating frequency.     

Electrodynamic acceleration of ultraheavy molecular ions

The design of an “electrodynamic accelerator” for ultraheavy molecular ions with masses of order 10⁶ Da is analyzed. It is shown that these ions can be efficiently accelerated to energies of hundreds of kilo-electronvolts over lengths no greater than 20 cm by using a sequence of voltage pulses with amplitudes of several kilovolts and microsecond durations. This acceleration allows ultraheavy molecular ions to be efficiently recorded using conventional secondary electron multipliers or multichannel plates. Pis’ma Zh. Tekh. Fiz. 24, 84–88 (July 26, 1998)     

Mammographic mass segmentation using multichannel and multiscale fully convolutional networks

Breast cancer is one of the leading causes of death among women worldwide. Mammographic mass segmentation is an important task in mammogram analysis. This process, however, poses a prominent challenge considering that masses can be obscured in images and appear with irregular shapes and low image contrast. In this study, a multichannel, multiscale fully convolutional network is proposed and evaluated for mass segmentation in mammograms. To reduce the impact of surrounding unrelated structures, preprocessed images with a salient mass appearance are obtained as the second input channel of the network. Furthermore, to jointly conduct fine boundary delineation and global mass localization, we incorporate more crucial context information by learning multiscale features from different resolution levels. The performance of our segmentation approach is compared with that of several traditional and deep-learning-based methods on the popular DDSM and INbreast datasets. The evaluation indices consist of the Dice similarity coefficient, area overlap measure, area undersegmentation measure, area oversegmentation measure, and Hausdorff distance. The mean values of the Dice similarity coefficient and Hausdorff distance of our proposed segmentation method are 0.915 ± 0.031 and 6.257 ± 3.380, respectively, on DDSM and 0.918 ± 0.038 and 2.572 ± 0.956, respectively, on INbreast, which are superior to those of the existing methods. The experimental results verify that our proposed multichannel, multiscale fully convolutional network can reliably segment masses in mammograms.     

Nucleation and growth of a multicomponent metallic glass

The metallic glass samples of Fe ₆₇Co₁₈B₁₄Si₁ (2605CO), prepared by the melt spinning technique were procured from the Allied Corporation. The kinetics of crystallization of this multicomponent glassy alloy is studied using differential scanning calorimetry (DSC). The crystallization data have been examined in terms of modified Kissinger and Matusita equations for the nonisothermal crystallization. The results show enhanced bulk nucleation in general. At high heating rates added to it is surface induced abnormal grain growth resulting in fractal dimensionality. 5th IUMRS ICA98, October 1998, Bangalore.     

Agglomeration Techniques for the Manufacturing of “Instant” Granules from Fine Powder Mixtures

ABSTRACT

Fine particles exhibit desirable characteristics including large surface area and high solubility. However, loose bulk masses of such particles feature different properties which restrict their use for applications requiring easy dispersion and quick dissolution in liquids. After reviewing the fundamentals of wetting and dispersion, the parameters defining “instant products” are discussed. To obtain these characteristics in granulated materials, specific binding mechanisms must act between the powder particles forming the agglomerate. Examples of typical plants for the production of instant products are presented.     

Distribution of Water in Solid Pharmaceutical Systems

Abstract

Knowledge of the amount of moisture associated with particular components of a solid dosage form, as well as its state, are essential for the pharmaceutical formulator in attaining a system with optimal physical/chemical properties. Moisture is introduced into ultimately closed pharmaceutical systems either associated with the materials or in the headspace as relative humidity. This moisture will distribute (i. e., reequilibrate) between the various components and the headspace to attain a final water activity, aw (-relative humidity/100) in the vapor phase. The Sorption-Desorption Moisture Transfer (SDMT) model allows a priori prediction of this thermodynamic variable for systems in which uptake isotherms and dry masses for individual components, temperature, headspace volume and initial total system moisture content are known. Final component moisture contents are then obtained from the individual materials' respective isotherms. Practical applications of the SDMT model include the rational determination of: initial LOD values of the formulation and capsule to avoid capsule brittleness problems, an adequate headspace volume above nonhydrating crystalline substances to protect against deliquescence, and the appropriate amount of desiccant for a solid product.     

Nuclear collisions induced by single-cycle laser pulses: Molecular approach to fusion

Abstract

We study the possibility for energetic nuclear collisions in a gas of molecules driven by ultra-intense and ultra-short laser pulses. The idea is to use the fact that nuclei in a molecule can be pre-aligned in front of each other and can be driven into each other by a very strong (field intensities approaching 10²³ W/cm²) and ultra-short (few-femtosecond, single-cycle) laser pulse, since the nuclei of different masses will acquire different velocities when driven by the same electric field. The nuclei may collide with high kinetic energy needed to overcome the Coulomb barrier, and these collisions may lead to fusion. We have performed classical simulation of nuclear motion and a simple statistical ensemble calculation. Our results show that nuclear collisions may occur on a sub-attosecond time scale, during which the nuclei will experience large acceleration and emit zeptosecond bursts of light.     

Cryptanalysis and improvement on a conference key distribution system

Abstract

In 1993, Wu and Yeh proposed a conference key distribution system based on cross product. In this paper, we will show that Wu and Yeh's system is breakable. We also propose a modified scheme for the conference key distribution system under the same assumption, which can achieve better security.     

On Vortices Induced in Superfluid Films by Crossed Electric and Magnetic Fields

The behaviour of a superfluid Bose-gas in crossed electric E and magnetic H fields is studied. It is shown that in the case when the two-dimensional divergence div ₂[E×H] differs from zero, the crossed fields induce the appearance of quantized vortex threads in the electroneutral superfluid system.     

Preparation information and optimal decompositions for mixed quantum states

Abstract

Consider a joint quantum state of a system and its environment. A measurement on the environment induces a decomposition of the system state. Using algorithmic information theory, we define the preparation information of a pure or mixed state in a given decomposition. We then define an optimal decomposition as a decomposition for which the average preparation information is minimal. The average preparation information for an optimal decomposition characterizes the system–environment correlations. We discuss properties and applications of the concepts introduced above and give several examples.     

Organic superconductors with an incommensurate anion structure

Abstract

Superconducting incommensurate organic composite crystals based on the methylenedithio-tetraselenafulvalene (MDT-TSF) series donors, where the energy band filling deviates from the usual 3/4-filled, are reviewed. The incommensurate anion potential reconstructs the Fermi surface for both (MDT-TSF)(AuI₂)_0.436 and (MDT-ST)(I₃)_0.417 neither by the fundamental anion periodicity q nor by 2q, but by 3q, where MDT-ST is 5H-2-(1,3-dithiol-2-ylidene)-1,3-diselena-4,6-dithiapentalene, and q is the reciprocal lattice vector of the anion lattice. The selection rule of the reconstructing vectors is associated with the magnitude of the incommensurate potential. The considerably large interlayer transfer integral and three-dimensional superconducting properties are due to the direct donor–donor interactions coming from the characteristic corrugated conducting sheet structure. The materials with high superconducting transition temperature, T_c, have large ratios of the observed cyclotron masses to the bare ones, which indicates that the strength of the many-body effect is the major determinant of T_c. (MDT-TS)(AuI₂)_0.441 shows a metal–insulator transition at T_MI=50 K, where MDT-TS is 5H-2-(1,3-diselenol-2-ylidene)-1,3,4,6-tetrathiapentalene, and the insulating phase is an antiferromagnet with a high Néel temperature (T_N=50 K) and a high spin–flop field (B_sf=6.9 T). There is a possibility that this material is an incommensurate Mott insulator. Hydrostatic pressure suppresses the insulating state and induces superconductivity at T_c=3.2 K above 1.05 GPa, where T_c rises to the maximum, T_c^max=4.9 K at 1.27 GPa. This compound shows a usual temperature–pressure phase diagram, in which the superconducting phase borders on the antiferromagnetic insulating phase, despite the unusual band filling.