Ampoule Diameter Research Articles

Stagnation Pressure in Liquid Needle-Free Injection: Modeling and Experimental Validation

Liquid needle-free injectors employ high-velocity liquid jets to deliver drugs and vaccines. Several parameters are critical to the injection quality: nozzle diameter, volume of drug delivered, ampoule diameter, pressure that drives liquid volume, and impact gap (distance between piston and trigger). A physical model is presented to calculate the stagnation pressure of the injection jet. Two types of the injection systems were tested: a spring-powered system and a voice-coil powered system. The calculation results show that the variation of stagnation pressure with time matches the experimental measurement under the same system conditions. The maximum stagnation pressure determines whether the jet can erode and penetrate into the skin. The maximum stagnation pressure was calculated under three conditions: different volumes, different spring rates and different ampoule diameters, and the results were compared with the experimental measurements. The experiments validated the physical model. Keywords: Liquid needle-free injection, modeling, stagnation pressure, jet, voice-coil, Resistant Force, Ring Seal

Investigation of SR method grown 〈0 0 1〉 directed KDP single crystal and its characterization by high-resolution X-ray diffractometry (HRXRD), laser damage threshold, dielectric, thermal analysis, optical and hardness studies

〈0 0 1〉 directed potassium dihydrogen orthophosphate (KDP) single crystal was grown by Sankaranarayanan–Ramasamy (SR) method. The 〈0 0 1〉 oriented seed crystals were mounted at the bottom of the platform and the size of the crystals were 10 mm diameter, 110 mm height. Two different growths were tried, in one the crystal diameter was the ampoule's inner diameter and in the other the crystal thickness was less than the ampoule diameter. In the first case only the top four pyramidal faces were existing whereas in the second case the top four pyramidal faces and four prismatic faces were existing through out the growth. The crystals were grown using same stoichiometric solution. The results of the two growths are discussed in this paper. The grown crystals were characterized by high-resolution X-ray diffractometry (HRXRD), laser damage threshold, dielectric, thermal analysis, UV–vis spectroscopy and microhardness studies. The HRXRD analysis indicates that the crystalline perfection is excellent without having any very low angle internal structural grain boundaries. Laser damage threshold value has been determined using Nd:glass laser operating at 1054 nm. The damage threshold for the KDP crystal is greater than 4.55 GW cm −2. The dielectric constant was higher and the dielectric loss was less in SR method grown crystal as against conventional method grown crystal. In thermal analysis, the starting of decomposition nature is similar in SR method grown KDP crystal and conventional method grown crystal. The SR method grown KDP has higher transmittance and higher hardness value compared to conventional method grown crystals.

Preparation and characterizations of thallium bromide single crystal for room temperature radiation detector use

Thallium bromide (TlBr) crystal of 8-mm-diameter, preferentially oriented in [1 1 0] direction has been prepared using a melt-based method without mechanical vibrations. Analyses on the crystal quality and growth process were made based on characterizations of X-ray diffraction, rocking curve, ultraviolet absorption and transmittance spectrum. Most section of the crystal exhibits crystalline perfection and low stress, and its bandgap was calculated to be 2.88 eV. Influence of ampoule diameter on crystal quality has been discussed. Resistivity of the material was measured to be over 10 10 Ω cm. Spectroscopic response of the fabricated detectors to 241Am shows 59.5 keV peak with the resolution of 38.27%.

Effect of crucible diameter reduction on the convection, macrosegregation, and dendritic morphology during directional solidification of Pb-2.2 wt pct Sb alloy

The Pb-2.2 wt pct Sb alloy has been directionally solidified in 1-, 2-, 3-, and 7-mm-diameter crucibles with planar and dendritic liquid-solid interface orphology. For plane front solidification, the experimentally observed macrosegregation along the solidified length follows the relationship proposed by Favier. Application of a 0.4 T transverse magnetic field has no effect on the extent of convection. Reducing the ampoule diameter appears to decrease the extent of convection. However, extensive convection is still present even in the 1-mm-diameter crucible. An extrapolation of the observed behavior indicated that nearly diffusive transport conditions require ampoules that are about 40 microns in diameter. Reduction of the crucible diameter does not appear to have any significant effect on the primary dendrite spacing. However, it results in considerable distortion of the dendrite morphology and ordering. This is especially true for the 1-mm diameter samples.

Can Propagation of Gas Bubbles Lead to Detached Solidification? Experiments on Freezing of Water

A vertical Bridgman-Stockbarger apparatus was used to directionally solidify water upward, in the hope that detached solidification would evolve from gas bubbles forming on the wall. A large contact angle of the water on the ampoule wall and a high solubility of the dissolved gas caused gas bubbles or tubes to form only at the ampoule wall, and not in the interior. Gas tubes were often nearly periodically spaced around the ampoule wall, with a spacing that increased with ampoule diameter and decreased with freezing rate. The width of the gas tubes was nearly independent of the ampoule diameter and freezing rate. A high degree of detachment was obtained with a rough, nonwetting coating on the ampoule wall, but full detachment was not achieved. This indicates that detachment does not occur by propagation of a single gas bubble around the periphery of the freezing interface. The convection near the freezing interface influenced gas bubble formation, and was outward for a concave freezing interface and inward for a convex interface.

Growth of gallium antimonide by vertical Bridgman technique with planar crystal-melt interface

High quality single crystals of GaSb were grown using vertical Bridgman techique with a planar melt-solid interface. Various factors affecting the interface shape during growth were investigated. In general, the shape of the freezing isotherm was found to depend on the furnace temperature profile near the melt-solid interface, the ampoule lowering rate, the ampoule geometry, the mode of heat extraction from the tip of the ampoule and the extent of lateral heat loss from the side walls of the ampoule. A critical ratio of temperature gradient of the furnace at the melting point to ampoule lowering rate was found to be necessary for planar interface shape during the growth. The sensitivity of the interface shape was found to decrease with increasing temperature gradient of the furnace and ampoule diameter. Crystals grown by employing the flat melt-solid interface exhibited superior quality than those with non-planar interfaces.

Bulk growth of gallium antimonide crystals by Bridgman method

Gallium antimonide crystals were grown by the vertical Bridgman technique. Effects of ampoule diameter and dopant impurities (Te, P and In) on growth were studied. Crystal stoichiometry and homogeneity were verified with electron-probe microanalysis. Impurity distribution was investigated by secondary ion mass spectrometry (SIMS) and electron probe micro analysis. Variations of etch pit density (EPD) along the length and the diameter were studied by image analysis method. Resistivity, mobility and carrier concentrations were measured along the length of the crystal.

Diffusive‐convective mass transport of HgI2 in closed ampoules

AbstractThe mass transport rate of HgI2 in closed ampoules with the addition of He, Ar or Xe at different pressures (20–200 Torr) was gravimetrically measured. Diffusive and convective mass fluxes in the systems studied were calculated according to vapour transport models. The influence of technological parameters, i.e. temperature, pressure, kind of added gas, and ampoule diameter, on the mass transport of HgI2 vapour was studied. Mechanisms of vapour flow in the applied experimental conditions are discussed.

The growth and texture study of GaSb ingots

GaSb was synthetized from Ga of 6N and Sb of 5N5 purity. After the synthesis the crystallization took place in Bridgman-type growth systems. Terrestrial and space experiments aboard Salyut-6 have been performed. In terrestrial experiments depending on the growth parameters (pulling rate, ampoule diameter, etc.) macro−, or polycrystalline ingots showing a characteristic texture have been formed. It has been observed that in wider ampoules boules of better quality have grown, the diameter of individual crystals ranging from 1–3 cm. In the space experiment a high-quality bicrystal has been formed. Examining the texture of terrestrial samples, the orientation of crystallites, the number of low and wide angle grain boundaries have been determined using electron channelling (EC) patterns.

Deviation of freezing rate from translation rate in the Bridgman-Stockbarger technique I. Very low translation rates

An analytical solution is obtained for the deviations of freezing rate from translation rate in the Bridgman-Stockbarger technique. The equations include a finite length ampoule, differences in heat transfer coefficients between the two ends, insulation between the heater and cooler, and latent heat. The present result accounts for heat conduction only, and is valid for low travel rates, small ampoule diameters and/or high thermal conductivities. In all cases the freezing rate approaches the translation rate if the interface is sufficiently far from the ends of the ampoule. The length required to achieve this condition increases with increasing ampoule diameter, decreasing heat transfer coefficient, increasing thermal conductivity and increasing insulation thickness. This length shows a minimum versus the heater temperature for a fixed cooler temperature. The present results are in agreement with previously reported experimental data and numerical predictions.

Programmed and oscillatory motion in Bridgman-Stockbarger growth

The response of the solid-liquid interface was derived for a mechanical drive which is either oscillatory or programmed for a linear change. Because the interface responds in a linear fashion, Laplace transforms prove very powerful for problems of this type. As might be expected, the amplitude of the freezing rate fluctuations decreases as the frequency of the mechanical drive rate fluctuations increases. The damping increases as the heat transfer coefficient decreases, ampoule diameter increases, temperature difference between heater and cooler decreases, and as the insulation thickness increases.

Melt growth of single crystal ingots of GaSe by Bridgman-Stockbarger's method

Melt growth of GaSe single crystals by Bridgman-Stockbarger's method in ampoules with differently shaped bottoms has been investigated. It has been shown that the crystal perfection depends on the lowering rate and on the ampoule diameter and that the crystal orientation depends on the bottom shape and on the position of the ampoule with respect to the furnace isotherms.