Beam profile measurement of a solar-pumped iodine laser

Beam profile measurements have been made as a function of time within the laser pulse and C2F5I pressure. Measurements indicate that the profile is determined directly by the optical excitation volume, produced by the solar simulator, and that media distortion plays a minor role compared to the build up of quenching species during the lasing pulse.     

The Interlaminar Bond Strength of Flexible Polymer-Metal Laminates

An alternative test method to the traditional 180° “T” peel test has been developed for the measurement of interlaminar bonding in three-ply (polyester/aluminium/polypropylene) flexible-packaging, laminate materials. The new test is thought to involve mixed mode I (opening) and mode II (shearing) failure, and takes into account the yielding of the polypropylene layer during testing. The method allows more direct comparisons between materials to be made, and allows the measurement of strong bonds, where a peel test would result in yield or fracture of the substrate arms before debonding.     

Non-Isothermal crystallization of isotactic polypropylene in dotriacontane. I: Effects of dilution,cooling rate,and nucleating agent addition on overall crystallization kinetics

The overall non-isothermal crystallization kinetics for nucleated and non-nucleated isotactic polypropylene (iPP) in dotriacontane systems was investigated. Adipic acid was used as the nucleating agent. Crystallization peak temperature was determined via differential scanning calorimetry as a function of the experimentally controlled variables iPP concentration, cooling rate, and nucleating agent concentration. The influence of these variables on crystallization mechanism and spherulitic structure as implied by the Ozawa and Ziabicki analyses was determined. The non-isothermal crystallization kinetics presented here are the first for iPP-diluent systems with and without nucleating agent.     

Kinetics of volume expansion during infusion of Ringer’s solution based on two volume model

In this work mathematical models were developed to represent the kinetics of volume changes of fluid spaces associated with infusion of Ringer’s solution. During infusion of Ringer’s solution, the human body is assumed to be characterized by the two-fluid space model which has second volume space in addition to the first volume so that fluid exchanges between these two spaces are possible. Various infusion types were tested to accommodate different medical situations. Volunteers were given Ringer’s solution and the changes in blood hemoglobin were detected. From the comparison with experimental data, the two-fluid space model was found to represent adequately the kinetics of human volume expansion during infusion of Ringer’s solution.     

A study on the deposition of pyrolytic carbons from hydrocarbons

A new method for forming isotropic, laminar, and columnar pyrolytic carbons is proposed. For this, a low RPM (below 2.4 rpm) tumbling bed has been used to deposit pyrolytic carbons from hydrocarbon gases. All deposits were made on graphite substrates from propane and methane at a constant temperature of 1200°C. The microstructures of the pyrolytic carbons deposited were dependent on the flow pattern of the reactant gas, the rpm of the reactor, the hydrocarbon concentration, the nature of the hydrocarbon, and the geometry of the bed. Isotropic pyrolytic carbon is formed under deposition conditions where homogeneous nucleation occurs in the gas phase and at the gas flow conditions where the gas-borne droplets can collide on the substrate. Laminar carbon is formed under deposition conditions where homogeneous nucleation does not occur in the gas phase and at gas flow conditions where the carbon species existing in the bulk of the gas phase can collide on the substrate. Columnar carbon is formed when any carbon products existing in the bulk of the gas phase cannot collide on the substrate. The suggested deposition mechanism can also be applied to pyrolytic carbons deposited in a fluidized bed or in a stationary bed. In particular, isotropic carbon can be obtained even in a stationary bed if the requirements for the deposition of the isotropic carbon described above are satisfied.     

The interpretation of GLC triglyceride data for the determination of cocoa butter equivalents in chocolate: A new approach

A new approach to interpret triglyceride data obtained by gas liquid chromatography (GLC) in order to determine cocoa butter equivalents (CBE) in chocolate is described. The approach is based on the known straight line relationship which exists between the C₅₀ and C₅₄ triglycerides of cocoa butter of different origins and the realization that, for currently available CBE conforming to CAOBISCO’s criteria, a similar band relationship exists. The technique described enables the quantity of unspecified CBE in a chocolate containing an unknown cocoa butter to be determined to an accuracy of ±1.5% when present in chocolate at the 5% level. Nut oils (almond, walnut or hazelnut) are sometimes present in mainland European chocolates and, should CBE also be present, it is possible to calculate the combined percentages of nut oil and CBE in the chocolate. The method of interpretation described is not dependent on a particular GLC technique for determining triglycerides. Interpretation of other laboratories’ results obtained using different GLC instruments and procedures has shown that the method enables any CBE present in the fat under examination to be determined accurately. The method compensates for variations in the composition of CBE and for the differences between cocoa butters of different origin. A detailed knowledge of CBE compositions is not required and only a few cocoa butter/CBE standards are necessary. The method described is graphical, enabling small laboratories not equipped with microcomputers to utilize the method. The calculation can, however, be programmed for a computer.     

Effect of temperature on polymer migration II: Concentration equation

Polymer migration is a generally well-known phenomenon in a flow field, and it has been verified that the sources of such phenomena are nonhomogeneity of the flow, concentration effects and hydrodynamic interactions between the polymer molecules. In addition, temperature effects were found to be another source of polymer migration. The Langevin equation for a polymer molecule was first derived from single chain dynamics using a kinetic theory for the bead-spring elastic harmonic dumbbell model, as described in part I (reference [1]). In this paper the diffusion equation and concentration profile of the polymer molecules induced by a temperature gradient are obtained from the Fokker-Planck equation. A new differential operator is also introduced to calculate the concentration profile. From the concentration equation obtained in the general flow geometry, we find that in dilute polymer solution there are significant effects on the polymer migration not only due to the nonhomogeneity of the flow field but also due to temperature gradients.     

Creep and drying shrinkage of calcium silicate pastes IV. Effects of accelerated curing

The dependent deformations and evidence of structural changes were measured on pastes of C₃S containing CaCl₂, and on pastes of C₃S or a C₃S/C₂S blend cured at 65°C. It was concluded that the addition of CaCl₂ enhances the role of the “pore component” in controlling irreversible strains even when well-hydrated pastes are dried. The formation of ore stable CSH at 65°C can explain the reduction in time-dependent deformations observed for these pastes. Even though a change in pore size distribution occurs at 65°C, it is not considered to affect irreversible strains in well-hydrated pastes.     

Non-Isothermal crystallization of isotactic polypropylene in dotriacontane. II: Effects of dilution,cooling rate,and nucleating agent addition on growth rate

Non-isothermal crystallization growth rates of nucleated and non-nucleated isotactic polypropylene (iPP) in dotriacontane were determined experimentally by thermal optical microscopy. Adipic acid was used as the nucleating agent. The non-isothermal growth rates of the nucleated and non-nucleated systems were compared with experimentally determined isothermal growth rates. The Lauritzen and Hoffman growth rate equation, originally developed for isothermal crystallization, was modified to describe the non-isothermal growth. The modified Lauritzen-Hoffman equation was used to predict isothermal growth rates from non-isothermal crystallization for the nucleated and non-nucleated polymer-diluent mixtures. This study is the first to deal with polymer-diluent-nucleating agent systems vital to membrane production.