Plastic Vessels Research Articles

Behaviour of viscoelastic-viscoplastic spheres and cylinders—Partly plastic vessel walls

The material model consists of a viscoelastic Burgers element and an additional viscoplastic Bingham element when the effective stress exceeds the yield stress. For partly plastic vessel walls, expressions are derived for the stress and strain state in pressurised or relaxation loaded thick-walled cylinders in plane strain and spheres. For the spherical problem, the material compressibility is accounted for. The influence of the different material parameters on the behaviour of the vessels is evaluated. It is shown that the magnitude of the Maxwell viscosity is of major importance for the long-term behaviour of thick-walled partly plastic vessels.

Analysis of filament wound vessel using finite elements

A special three dimensional finite element was developed for the strain analysis of fiber reinforced plastic vessels containing discontinuities such as manhole connections or nozzles. The element handles the many anisotropic layers by using a different elastic constant matrix for each lamina orientation. Results obtained from a cylindrical vessel show good agreement with classical lamination theory and experimental results.

Behaviour of viscoelastic-viscoplastic spheres and cylinders—Fully plastic vessel walls

The material model consists of a viscoelastic Burgers element and an additional viscoplastic Bingham element when the effective stress exceeds the yield stress. For fully plastic vessel walls, exact closed-form expressions arc derived for the stress and strain state in pressurised or relaxation loaded thick-walled cylinders in plane strain and spheres. For the spherical problem, the material compressibility is accounted for. The influence of the different material parameters on the behaviour of the vessels is evaluated. It is shown that the magnitude of the Maxwell viscosity is of major importance for the long-term behaviour of thick-walled fully plastic vessels.

Systematic Error Associated with Apparatus 2 of the USP Dissolution Test V: Interaction of Two Tableted Prednisone Formulations with Glass and Plastic Vessels

Recently marketed glass vessels that are uniform and pass USP specifications were compared with uniform plastic vessels that also pass USP specifications. Two lots of prednisone tablets, Tablet 1 and Tablet 2, were tested in both types of vessels. Tablet 1 gave higher results (+12.7% of label claim) in glass vessels at 50rpm but gave equivalent results in either vessel at 75rpm. Tablet 2 gave equivalent results in either vessel at 50rpm but gave higher results (+22% of label claim) in glass vessels at 75rpm. The type of vessel used to obtain dissolution results for tablets should be specified.

The design of ends of cylindrical pressure vessels in glass reinforced plastic

A design procedure for torispherical and semi-ellipsoidal ends of cylindrical chopped strand mat glass-fibre reinforced plastic pressure vessels is presented. The method is applicable where all layers of reinforcement are of the same type. The procedure takes account of the effect of the change of shape of the end due to pressure. The procedure is based on either maximum stress or maximum strain. The criteria used aim to achieve consistency with the BS.4994 method of calculating the design unit loading of laminates and allow for the biaxial stress states which occur in the vessels.

Feeding behaviour of the Japanese loach,Misgurnus anguillicaudatus (Cobitididae)

The feeding behaviour of a Japanese loach,Misgurnus anguillicaudatus was experimentally analyzed. From observations the behaviour patterns were described. The adult fish responded to a piece of thread soaked with filteredTubifex homogenate (Tubifex solution) and showed feeding behaviour. But they ignored an unsoaked piece of thread. LivingTubifex kept in a glass cell failed to elicit feeding behaviour in the fish. A gauze-covered vessel withTubifex solution buried in the sand substrate released feeding behaviour in fish in its vicinity. It follows that the feeding behaviour of this fish is induced by some chemical stimuli. WhenTubifex solution was introduced at the central area of the plastic vessel with a fish, the fish suddenly started the Feeding-crawl and showed Gulp which was composed of Dig and Twist. Using sand particles, it was shown that intake of materials into the digestive tract occurs only at the moment of Twist and not any other time. The standard feeding patterns ofMisgurnus anguillicaudatus are thus quick inhalation of organic matter together with substrate, occurring at the moment of Twist, which is released at the place where the fish received the appropriate chemical stimuli.Misgurnus anguillicaudatus is regarded as a typical “detritus feeder”.

Use of glass-reinforced plastic vessels in petrochemical production plants

At present, petrochemical plant production equipment is made of scarce high-alloy steels and alloys or carbon steel with subsequent chemical protection. Traditional methods of protection frequently do not provide reliable and safe service of equipment for the length of the normal operating life. One of the effective methods of combatting corrosion is the use of glass-reinforced plastic equipment. Glass-reinforced equipment is not subject to electrochemical corrosion and has a high chemical resistance. Weight is approximately a third of similar vessels. The paper provides recommendations and precautions for the production, installation, use and maintenance of glass-reinforced plastic vessels.

Cell Cycle Kinetics of Cultured Human Epidermal Keratinocytes

When stratified epithelia maintained in culture are used for autoradiographic studies of labeling index, the emulsion is usually placed over the uppermost strata of the culture. In many cases the distance from the basal cell nucleus to the emulsion exceeds the average pathlength of beta-particle emissions from 14C or 3H. We describe a technique for inverting the cultures so that the emulsion can be brought into close association with the basal cells. Attempts to label cultured human epidermal keratinocytes using a pulse of [3H]- or [14C]-thymidine produced labeling only at the periphery of the colonies. This was noted when emulsion was laid on top of the colonies but also when the emulsion was in close contact with the "basal cells" adhering to the plastic culture vessel. Continuous labeling of the cultures produced nearly 100% labeling of all the basal layer, i.e., central and peripheral, indicating that the central cells were also in rapid cell cycle. The results are interpreted as indicating the presence of an efficient barrier to free diffusion over the center of the colonies, presumably due to the presence of several layers of corneocytes. Percent labeled mitoses (PLM) studies produced an unusual PLM curve with a well-defined third peak which showed a higher PLM than the second peak. These results may indicate that the cultures contain discrete cell populations with different cell kinetic phase durations.

Tensile Behavior of Laminates Used for Making Fiber Reinforced Plastic Vessels

The tensile behavior of laminates consisting of layers of veil, mat and woven roving is investigated. The results show that the fracture strain of the laminate is always smaller than the fracture strain of the more brittle constituent layer. It is shown that the rule of mixture can be used to calculate the modulus of the laminate knowing the moduli of the individual layers. The rule of mixture can also be used to calculate the tensile strength provided that the stress in the more ductile layer corresponding to the fracture strain of the more brittle layer is used.

Microwave sterilization of plastic tissue culture vessels for reuse.

A simple protocol has been developed for recycling plastic tissue culture vessels. The killing properties of microwaves were used to decontaminate plastic tissue culture vessels for reuse. Nine bacterial cultures, four gram-negative and five gram-positive genera, including two Bacillus species, were used to artificially contaminate tissue culture vessels. The microwaves produced by a "home-type" microwave oven (2.45 gHz) were able to decontaminate the vessels with a 3-min exposure. The same exposure time was also used to completely inactivate the following three test viruses: polio type 1, parainfluenza type 1 (Sendai), and bacteriophage T4. The recycling procedure did not reduce the attachment and proliferation of the following cell types: primary chicken and turkey embryo, HEp-2, Vero, BGMK, and MK-2.

Strain Analysis of Dual Laminate Cylindrical Fiber Glass Reinforced Plastic Vessel

Strains in a dual laminate fiber reinforced plastic cylindrical vessel are measured when the internal pressure increases up to 0.96 MPa (140 psig). Laminate theory was used successfully in calculating the strains. Reason able agreement was obtained between experimental and theoretical results. A new formulation is developed to calculate optimal winding angles such that the ratio of strains along different directions is minimum. This would provide efficient strain limited designs.

Systematic Error Associated with Apparatus 2 of the USP Dissolution Test II: Effects of Deviations in Vessel Curvature from That of a Sphere

Dissolution vessels made from glass or plastic are recognized by the USP as being suitable for dissolution testing. Glass vessels with a bottom inside curvature flatter than that of a sphere can cause a high bias in dissolution results; vessels with a steeper curvature can cause a low bias. The inside bottom curvature of plastic vessels adhered closely to the curvature of a sphere. The plastic vessels are preferable for use if the drug is not adsorbed and the vessel is not attacked by the dissolution medium. Bias in results between individual positions of a dissolution apparatus was traced to two shafts which were not vertical.

Quantitative evaluation of pharmaceutical effervescent systems I: Design of testing apparatus

Two new devices were developed to monitor the reactivity of pharmaceutical effervescent systems. The first method monitored carbon dioxide pressure generation during the effervescent reaction in a plastic pressure vessel fitted with a pressure gauge. The second method monitored weight loss, attributed to carbon dioxide loss to the atmosphere, by means of a double cantilever beam and an electromagnetic proximity transducer. In the pressure device, the quantification of an effervescent reaction was accomplished by measuring the dissolution time of the effervescent system and the pressure generated. Quantification of an effervescent reaction using the beam device utilized the total carbon dioxide weight loss, the rate of weight loss, and the effervescent reaction lag time.

Short-term in-plane stiffness and strength properties of csm-reinforced polyester laminates

As part of a large programme concerned with the structural behaviour of glass-reinforced plastic pressure vessels, tension and four-point bend tests have been conducted on specimens cut from flat sample panels associated with fourteen different vessels. Although the same chopped strand mat/polyester resin system was used throughout, the number of layers of reinforcement hence the overall laminate thickness varied. To relate the stiffness and strength properties determined from these tests to the wall material of the specimen pressure vessels, it was found necessary to take account of both differences in percentage glass content and the effect of the resin-rich gel coats present on the surfaces of these laminates. This latter was allowed for by estimating the thickness and properties of these gel coats and applying simple laminate theory to derive properties for the actual chopped strand mat-reinforced composite alone. Empirical relationships were then obtained between each property and the corresponding mass fraction of glass. Using these results, a method of calculating realistic values of tension and bend properties for laminated structures was devised. As well as enabling closer estimates of the measured strains in the specimen pressure vessels to be made, these methods have implications for design procedures such as the current UK code for glass glass-reinforced plastic pressure vessels, BS 4994.

The strength and deformations of torispherical ends for glass-reinforced plastic pressure vessels—Part 2: Effect of torisphere geometry for ends of fixed head height

Four further glass-reinforced plastic cylindrical pressure vessels with torispherical dished ends have been tested to destruction. Together with two vessels already reported on in Part 1 of this paper, these specimens form part of a group with the same head height of 0·25 m but with three different torus radii of 0·1 m, 0·146 m and 0·188 m, giving crown radii of 0·71 m, 0·8 m and 1·0 m, respectively (two vessels of each geometry were tested). As in Part 1, results from the tests were compared with those suggested by the current UK design code (BS 4994) and the predictions of a computer-based elastic stress analysis (BOSOR 4). In contrast to BS 4994, BOSOR 4 indicates that there is little difference in strength between dished ends with the two larger knuckle radii. A torus radius of 0·1 m, however, does produce a significant increase of maximum stress and strain. In fact, of the four additional vessels tested, only those two of this latter geometry ultimately failed in the dished end, those of knuckle radius 0·146 m rupturing in the cylinder.

The strength and deformations of torispherical ends for glass-reinforced plastic pressure vessels—Part I: Effect of torus radius/cylinder diameter ratio on ends with sphere radius equal to cylinder diameter

Six glass-reinforced plastic cylindrical pressure vessels with torispherical end closures have been tested to destruction. Each vessel was of 0·01 nominal thickness/diameter ratio and had an end geometry with the spherical radius equal to the cylinder diameter of 1 m. Three different torus radii of 0·29, 0·19 and 0·1 m were used to give head heights of 0·32, 0·25 and 0·19 m, respectively (two vessels of each geometry were tested). Results from the tests were compared with those suggested by the current UK design code (BS 4994) and the predictions of a computer-based elastic stress analysis (BOSOR 4). These all confirm that maximum stresses and strains increase with decreasing knuckle radius. It was also found that, because of the high elastic strains of GRP, the change of geometry under pressure makes a significant contribution to the ultimate strength of these ends. The result of this, together with the effect of some local wall thickening, was to strengthen the ends to the extent that failure took place in the torisphere for only three of the six vessels tested.

Cytostatic Effect of Spleen Cells of Cyclophosphamide-Treated Mice on Tumor Cells

Spleen cells of mice receiving an i.p. injection of a sublethal dose of cyclophosphamide (CY) have the ability to inhibit tumor growth in vitro. This effect is dose dependent and is maximal at the peak of the spleen regeneration which follows the phase of atrophy due to CY toxicity. This cytostasis is neither tumor-specific nor strain-restricted and the cells responsible for this inhibition of tumor cell multiplication have the characteristics of macrophages: they lack the Thy 1-2 antigenic marker, appear in CY treated nude mice, stick on plastic vessels, and are retained by adherence columns (nylon wool or Sephadex G10); their activity is greatly reduced when a specific macrohpage toxic reagent such as carrageenan is added to the cultures. The effector cells are similar to those which are able to suppress the response of normal splenocytes to T and B mitogens, and which appear in the same conditions of induction, after CY injection.

The modulation contrast microscope: principles and performance

SUMMARYThe modulation contrast microscope produces an image of high contrast and resolution. The image has a three‐dimensional appearance wherein a rounded object appears dark on one side, bright on the other with grey in between against a grey background. The performance features are optical sectioning, directionality, high resolution and control of contrast and coherence. A bright field microscope is converted to the modulation contrast microscope by adding the modulator, a special amplitude filter, in the objective. A slit aperture part of which is polarized is placed before the condenser. Below this is a rotatable polarizer. The modulator processes light from opposite gradients oppositely, that is brighter for one and darker for the other; thereby preserving the sign. The diffraction theory has been extended to show that gradient image intensity is the intensity of the zero order and when modified by the modulator creates a high contrast image.The modulation contrast microscope is simple and easy to adjust. It is useful in reflected and transmitted light systems, with plastic and glass vessels as well as in combination with fluorescence systems and polarization techniques. There is virtually no limit to the type of specimen that can be studied.

Experimental study of thermally stratified hot water storage tanks

Temperature stratification in hot water storage systems was studied experimentally. In particular, high extraction rates from plastic cylindrical vessels were emphasized. Data were taken at various length to diameter ratios, inlet-outlet temperature differences and mass flow rates. The effect of inlet and exit port configuration on thermal stratification was also studied. The data were empirically correlated to yield useful relations for the design of effective hot water storage systems. Finally, a novel inlet and exit configuration scheme was designed for an 80 gal. (300 l.) and a 500 gal. (1900 l.) storage tank.

A method for in situ embedding of cultured cells grown in plastic tissue culture vessels for transmission electron microscopy

A method for in situ embedding of cultured cells grown in plastic tissue culture vessels for transmission electron microscopy