Showing papers by "McMaster University published in 1972"
TL;DR: In this article, the content of free ZrO2 in partially stabilized zirconia ceramics by X-ray diffraction techniques was determined by linear calibration curves.
Abstract: Linear calibration curves were developed for determining the content of free ZrO2 in partially stabilized zirconia ceramics by X-ray diffraction techniques. Two methods were studied. The matrix method, in which free ZrO2 was considered to be distributed in a matrix (the cubic phase), gave approximately equal mass absorption coefficients for the monoclinic and cubic phases. The polymorph technique, in which the cubic phase was considered to be a polymorph of ZrO2 and in which integrated intensities were used, gave the better results.
1,302 citations
TL;DR: Only the impairment produced by the TPA lesion was consistent with a difficulty in the formation of such associations, an interpretation which is strengthened by a consideration of the gross behavioral abnormalities that have been described repeatedly following this same lesion.
844 citations
TL;DR: Methods have been developed for the preparation of suspensions of washed platelets from humans and platelets suspended in Eagle's tissue culture medium containing albumin were more responsive to ADP than platelets in Tyrode's‐albumin solution.
Abstract: Summary: Methods have been developed for the preparation of suspensions of washed platelets from humans Heparin is used in the washing fluids to prevent: thrombin generation and apyrase is used to prevent adenine nucleotide accumulation Platelets suspended in Eagle's tissue culture medium containing albumin were more responsive to ADP than platelets in Tyrode's-albumin solution Addition of fibrinogen is required for maximum sensitivity to ADP-induced aggregation These platelets can be stored for 4 hr or more at 37°C in the presence of apyrase and maintain their ability to aggregate upon the addition of low concentrations of ADP
Without apyrase the platelets gradually become insensitive to ADP upon storage at 37°C; this is presumably caused by the accumulation of ADP in the suspending fluid because sensitivity can be partially restored by the addition of apyrase and further incubation
835 citations
TL;DR: An experimental study of thermal polymerization of styrene in the temperature range 100-200°C and conversion range 0-100% is reported in this paper, where conversions, molecular weight averages, and molecular weight distributions were measured.
Abstract: An experimental study of thermal polymerization of styrene in the temperature range 100–200°C and conversion range 0–100% is reported Conversions, molecular weight averages, and molecular weight distributions were measured A kinetic model with third-order initiation gives a satisfactory fit of conversion and number- and weightaverage molecular weights over the ranges of temperature and conversion investigated This model should find use in the design, simulation, and optimization of polystyrene reactors
376 citations
TL;DR: A simple possible form of the strain energy function for soft biological tissues is studied and the similarity of the result of an example problem to experimental results is encouraging.
354 citations
TL;DR: In this paper, a new class of microwave filters, hairpin line and hybrid hairpin-line/half-wave parallel-coupled-line filters, was reported, which is particularly well suited for microstrip and TEM printed-circuit realizations because grounding of the filter resonators is generally not required.
Abstract: A new class of microwave filters, hairpin-line and hybrid hairpin-line/half-wave parallel-coupled-line filters, is reported. This class of filters is particularly well suited for microstrip and TEM printed-circuit realizations because grounding of the filter resonators is generally not required. Hairpin-line filters have been divided into two types. The first (Type A) is characterized by having its input and output lines open-circuited at their ends. The Type A filter has been found to yield practical impedance levels for narrow to approximately 25-percent bandwidths. The second (Type B) is characterized by having its input and output lines short-circuited at their ends. However, because of space limitations, details of the Type B filter are not presented in this paper. Theoretical background and design equations for Type A bandpass filters are presented. Experimental data for several stripline filters of 5- and 20-percent bandwidths are given. Experimental results for two microwave-integrated-circuit (MIC) filters are discussed.
258 citations
TL;DR: A coherent binary FSK modulation system is discussed, that has a low deviation ratio and uses as receiver a self-synchronizing circuit and a phase detector, which together achieve optimal decisions.
Abstract: A coherent binary FSK modulation system is discussed, that has the following properties: 1) it is phase coherent; 2) it has a low deviation ratio, h = \frac{1}{2}; 3 ) it occupies a small RF bandwidth, typically only 0.75 times the bit rate, without need for intersymbol interference correction; 4) it uses as receiver a self-synchronizing circuit and a phase detector, which together achieve optimal decisions; and 5) its error performance is about S dB better than that of conventional FSK.
239 citations
TL;DR: Partially stabilized zirconia (PSZ) ceramics in the system CaO-ZrO2 were characterized by optical microscopy as mentioned in this paper, which revealed that the microstructure provided an effective stress-relieving mechanism during thermal shock.
Abstract: Partially stabilized zirconia (PSZ) ceramics in the system CaO-ZrO2 were characterized. The microstructure, as revealed by optical microscopy, consisted of grains of pure ZrO2 distributed in a matrix of fully stabilized material. Electron microscopy showed that the matrix grains have a complex substructure of 1000-A domains of cubic and monoclinic ZrO2. The grains appeared to fit Ubbelohde’s concept of a hybrid single crystal. Evidence obtained indicated that the substructure provides an effective stress-relieving mechanism during thermal shock. It is proposed that initiation of phase inversion in pure ZrO2 domains, even at subtransition temperatures (by thermal stresses), creates an extremely large microcrack density. On the basis of Hasselman’s thermal-shock criterion, only quasi-static crack propagation occurs during thermal shock of PSZ; evidence is presented to support this concept.
204 citations
TL;DR: A simple alphabetical classification is offered as a means to codify the proteins of rhabdoviruses, using vesicular stomatitis virus as the prototype.
Abstract: A simple alphabetical classification is offered as a means to codify the proteins of rhabdoviruses, using vesicular stomatitis virus as the prototype.
190 citations
TL;DR: In this paper, Hartree-Fock calculations have been performed for the closed-shell nuclei 4 He, 16 O, 40 Ca, 48 Ca, 90 Zr and 208 Pb, using the density-dependent effective interaction of Sprung and Banerjee.
172 citations
TL;DR: It would appear that successful biological denitrification units can be designed in conjunction with existing activated sludge treatment facilities producing a nitrified effluent under winter conditions.
TL;DR: In this article, four theoretical approaches are presented for quantitatively determining the intensity of the internal circulation and the flow patterns inside and outside liquid water spheres falling at terminal velocity in air.
Abstract: Four theoretical approaches are presented for quantitatively determining the intensity of the internal circulation and the flow patterns inside and outside liquid water spheres falling at terminal velocity in air. The first approach assumes creeping flow outside and inside a water sphere, the second assumes potential flow outside and inviscid motion inside a water sphere, the third makes use of boundary layer theory, and the fourth approach uses a numerical method to solve the full Navier-Stokes equation of motion inside and outside a water sphere. The theoretical predictions are compared with data obtained from new quantitative wind tunnel experiments on spherical and deformed water drops. The results show that the creeping flow analysis greatly underestimates the strength of the internal velocity while the inviscid flow analysis greatly overestimates it. On the other hand, the results of the boundary layer approach and of the numerical approach agree reasonably well with the experimental data f...
01 Nov 1972-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this article, a critical appraisal of theory and experiments for both isothermal and forced velocity pearlite is presented, and a new perturbation procedure for definition of the optimal steady-state spacing is presented.
Abstract: A critical appraisal of theory and experiments for both isothermal and forced velocity pearlite is presented. It is concluded for binary systems that both the theoretical models for volume diffusion and boundary diffusion control are well-advanced and adequate for the purposes of experimental test. However, some ambiguity remains in the boundary diffusion model with respect to the thermodynamics of the boundary ”phase” region, so it is still not possible to predict absolute rates of transformation. The theoretical problem for ternary pearlites is also well understood, although rigorous theory seems intractable. A new perturbation procedure for definition of the optimal steady-state spacing is presented and amplified for both isothermal and forced velocity pearlite, and for both volume and boundary diffusion models. In terms of the critical spacing Sc for isothermal pearlite and the spacing at minimum undercooling Sm for forced velocity pearlite the predicted stability points are as follows: {fx2777-1} For isothermal pearlite these perturbation results correspond closely to the state of maximum entropy production rate while for forced velocity pearlite the correspondence is also satisfactory. A detailed analysis of the data leads us to reaffirm the author’s conclusions that the eutectoid reactions in Cu-12 pct Al and some related ternary alloys reported by Asundi and West are controlled by volume diffusion and that the eutectoid reaction in Al-78 Zn reported by Cheetham and Ridley is controlled by boundary diffusion. We conclude further after careful analysis that the pearlite reaction in Fe-0.8 C is controlled for the higher temperatures by volume diffusion of carbon in austenite. We are also led to state that the pearlite transformations in Fe-C-Mn and Fe-C-Ni occur for the most part in a nopartition regime and are therefore controlled by volume diffusion of carbon in austenite, while the transformations in Fe-C-Cr and Fe-C-Mo, being forced by thermodynamics to sustain partition of chromium and molybdenum, are controlled by phase boundary diffusion of the latter elements. nt]mis|M. P. PULS, formerly Postdoctoral Fellow, Department of Metallurgy and Materials Science, McMaster University, Hamilton, Ontario, Canada
TL;DR: The present experiments replicated Garcia and Koelling (1966) findings with one major change in experimental conditions: both taste and nongustatory CSs were presented in the absence of approach and ingestive behaviors to minimize involvement of ingestion in the associative process.
Abstract: Garcia & Koelling (1966) showed that if rats are poisoned after ingesting a flavored solution in the presence of audiovisual cues, they will subsequently avoid only the taste stimulus, whereas if they are shocked, they learn to avoid only the audiovisual cues. The present experiments replicated these findings with one major change in experimental conditions: both taste and nongustatory CSs were presented in the absence of approach and ingestive behaviors to minimize involvement of ingestion in the associative process. (The taste CS was presented by flushing the oral cavity with a saccharin solution under conditions in which the rat would not drink.) Despite these changes, Garcia and Koelling’s results were confirmed.
01 Jun 1972
TL;DR: In this paper, the Fe-C-Mn phase diagram of the proeutectoid ferrite transformation has been reexamined and several tie-lines have been determined using an experimental method designed to promote rapid equilibration.
Abstract: The portion of the Fe-C-Mn phase diagram which is relevant to the proeutectoid ferrite transformation has been reexamined. Several tie-lines have been determined using an experimental method designed to promote rapid equilibration and these are shown to be in good agreement with tie-lines estimated from thermodynamic data. The same thermodynamic information has been used to compute paraequilibrium phase boundaries.
TL;DR: The results indicate that factors regulating enzyme turnover show important changes as root cells mature and may be significant in determining steady state levels of the enzyme.
Abstract: The induction and reinduction of nitrate reductase in root tip or mature root sections show essentially a similar pattern: a lag, a period of rapid increase in enzyme activity and finally a period of relatively minor change. Both inductions are sensitive to 6-methylpurine and cycloheximide. Kinetic studies with 6-methylpurine suggest that the half-life of the messenger RNA for nitrate reductase in both sections is about 20 minutes. The rate of decay of nitrate reductase activity induced by transfer to a nitrate-free medium is slower in root tips (t½ = 3 hours) than in mature root sections (t½ = 2 hours). The enzyme from mature root sections is also less stable to mild heat treatments (27 C; 40 C) than the enzyme from root tip sections. The results indicate that factors regulating enzyme turnover show important changes as root cells mature and may be significant in determining steady state levels of the enzyme.
TL;DR: In this paper, the structure of βVPO5 was refined by full matrix least squares from the coordinates of the isostructural βVSO5 with 772 nonequivalent reflections measured on a General Electric quarter circle diffractometer.
TL;DR: In this article, two conditioned suppression experiments are reported which made use of compound summation as an index of excitatory properties of CSs and showed that compound tests revealed excitory properties after as limited a conditioning sequence as a single pairing with shock.
01 Dec 1972
TL;DR: In this article, the late stages of the isothermal proeutectoid ferrite reaction in Fe-C-Mn have been investigated theoretically and experimentally, and the growth rates and the diffusion profiles for the third temporal regime have been calculated on a local equilibrium model and compared with the metallographic and microprobe results for alloys within the two regions of supersaturation.
Abstract: The late stages of the isothermal proeutectoid ferrite reaction in Fe-C-Mn have been investigated theoretically and experimentally. For the growth of grain-boundary allotriomorphs three temporal regimes must be recognized. In the early regime the grain-size is infinite with respect to the diffusion length of carbon so the growth is parabolic. The middle regime involves the cumulative impingement of the carbon fields from opposite sides of the grains. This regime ends as the carbon activity approaches substantial uniformity through the ferrite and austenite. The final stage involves the extremely slow approach of the manganese towards uniform activity as well. These temporal regimes must be further subdivided into high and low super saturation regions. In the low supersaturation region segregation of manganese must occur at all times, while in the high supersaturation region it must occur significantly only for late times. The growth rates and the diffusion profiles for the third temporal regime have been calculated on a local equilibrium model and compared with the metallographic and microprobe results for alloys within the two regions of supersaturation. The agreement between theory and experiment is in all cases good.
TL;DR: A hypothetical sequence for the biogenesis of pyridoxol is advanced on the basis of the tracer evidence, and 5-Deoxyxylulose 1-phosphate and a branched chain 8-carbon sugar are postulated as intermediates.
01 Nov 1972-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this article, the relative effects of pearlite and spherodite on ductile, cleavage, and fatigue failure are summarized, and it is shown that neither the cleavage strength nor the fatigue endurance limit appear to depend directly on cementite content per se.
Abstract: The relative effects of pearlite and spherodite on ductile, cleavage, and fatigue failure are summarized. Neither the cleavage strength nor the fatigue endurance limit appear to depend directly on cementite contentper se. Spherodized steels cleave less readily than ferrite/pearlite steels. Ductile fracture resistance is lowered considerably by both types of cementite, pearlite being more deleterious. Ferrite/pearlite steels appear to exhibit slower fatigue crack growth rates at low stress intensity levels than high strength steels. At high stress intensity levels the behavior is reversed. Slip-incuded cracking of carbide lamellae appears easier than that of spherodized carbides. In ductile fracture situations the crack spreads progressively through a pearlite colony via preferential cracking of carbides and rupture of the intervening ferrite accompanied by large local shear strains. Fatigue fracture proceeds with formation of frequent branches, preferentially along the pearlite colony interface.
TL;DR: In this paper, the bulk polymerization of vinyl chloride initiated by AIBN at temperature levels of 30°, 50°, and 70°C has been studied and molecular weight averages and distribution (MWD) were measured by gel permeation chromatography.
Abstract: The bulk polymerization of vinyl chloride initiated by AIBN at temperature levels of 30°, 50°, and 70°C has been studied. Molecular weight averages and distribution (MWD) were measured by gel permeation chromatography. A model has been proposed which accurately predicts conversion to high levels and MWD. Molecular weight measurements show that transfer to monomer plays the important role in controlling molecular weight averages. Disproportionation is probably the dominant mode of termination.
TL;DR: This paper will attempt to summarize some of John Dacie’s contributions to the serology of AIHA and review the current state of knowledge under the following headings: the direct antiglobulin test, warm autoantibodies, cold autoantIBodies, sub-divided into high-titre cold agglutinins and the Donath-Landsteiner antibody and, finally, classification ofAIHA.
Abstract: The name ofJohn Dacie has been so inextricably bound with the development of knowledge about the autoimmune haemolytic anaemias (AIHA), that it is diflicult in a short paper to acknowledge all his contributions to the subject. Probably his frnest single achievement was the compilation of his book, The Haemolytic Anaemias in 1954; in the second edition one volume, part 11, published in 1962, is devoted exclusively to the autoimmune haemolytic anaemias. This volume not only reviewed the world literature up to that date, but also provided a summary of Dacie’s experience with 175 cases of autoimmune haemolytic anaemia, many of whose sera and red cells he had investigated personally. It is still the standard reference text for all who are interested in AIHA. John Dacie is essentially a laboratory worker at heart and in this paper we will attempt to summarize some of his contributions to the serology of AIHA and review the current state of knowledge. This will be done under the following headings: the direct antiglobulin test, warm autoantibodies, cold autoantibodies, sub-divided into high-titre cold agglutinins and the Donath-Landsteiner antibody and, finally, classification of AIHA.
TL;DR: The cytokinin-requiring tissue grown in the presence of N (6)-furfurylaminopurine contains less than 85 nanograms per kilogram of N(6)-(Delta(2)-isopentenyl) adenosine, which is the detectable limit under the conditions of the experiment.
Abstract: Cytokinins from both the free nucleoside pool and the transfer RNA have been isolated and identified in a habituated strain of tobacco pith callus (Nicotiana tabacum [L] var. Wisconsin 38). The transfer RNA of this strain contains both N(6)-(Delta(2)-isopentenyl) adenosine and N(6)-(4-hydroxy-3-methylbut-2-cis-enyl) adenosine. The trans-hydroxylated derivative is absent from the transfer RNA of this dark-grown tissue. N(6)-(Delta(2)-Isopentenyl)-adenosine was identified as a component of the free nucleoside pool in concentrations of about 10 micrograms per kilogram of tissue.The cytokinin-requiring tissue grown in the presence of N(6)-furfurylaminopurine contains less than 85 nanograms per kilogram of N(6)-(Delta(2)-isopentenyl) adenosine. This is the detectable limit under the conditions of the experiment.
TL;DR: A necessary condition for the existence of a resolvable balanced P-design is found, and the ''product theorems'' -techniques are used to generate these designs on the first, resp.
TL;DR: In this paper, the growth of nickel oxide layers on the (100), (110), and (111) crystal faces of nickel exposed to oxygen for periods up to 100 hr at temperatures in the range 500-800°C, these layers grow at a rate dependent upon the crystallographic orientation of the nickel face.
Abstract: A study has been made of the growth of nickel oxide layers on the (100), (110), and (111) crystal faces of nickel exposed to oxygen for periods up to 100 hr at temperatures in the range 500–800°C, These layers grow at a rate dependent upon the crystallographic orientation of the nickel face even at thicknesses within the scaling range. The (100) face oxidized more rapidly than the (110) and (111) nickel faces while the latter faces oxidized at different relative rates dependent upon temperature. A diffusional model is employed to interpret the oxidation kinetics wherein nickel transport proceeds in nickel oxide both by short-circuit diffusion at grain boundaries and by lattice diffusion.
TL;DR: Evidence is presented which illustrates that reactions observed at 6 to 8 hours did not have a necessary dependence upon the presence of proteinase activity in antigen preparations, and mechanisms underlying prolonged cutaneous allergic responses were considered.
Abstract: In a selected group of detergent industry workers, a close relationship was observed between cutaneous sensitivity and respiratory symptoms from exposure to air borne B. subtilis enzyme containing products. In intracutaneous tests with comparatively high concentrations of two B. subtilis products used commercially, prolonged responses which were generally maximal in diameter at 6 to 8 hours were present at the sites of 75 per cent of 35 "immediate" wheal and flare responses but not at skin test-negative sites. Precipitin reactions with human sera were nonspecific. Antibodies of the IgA and IgM classes were not detectable in the sera of most subjects with the responses observed at 6 to 8 hours. Antibodies of the IgG class were present in most of these sera but were also present in the sera of some subjects with immediate reactions without ensuing responses. Apart from the obligatory preceding "immediate" wheal and flare reaction, responses which evolved over 6 to 8 hours could not be related to any immunologic finding. Evidence is presented which illustrates that reactions observed at 6 to 8 hours did not have a necessary dependence upon the presence of proteinase activity in antigen preparations. Prausnitz-Kustner reactions to B. subtilis antigens and to reagreed antigen E evolved over a period of hours and were similar to gross appearance to those seen in actively sensitized industrial workers. In the discussion, these results are considered in relation to mechanisms underlying prolonged cutaneous allergic responses.