Plastic Ones Research Articles

Acoustic emission investigations of the ductility of L12Al3Ti+Cr under high hydrostatic pressure

Compression and tension tests were carried out on the L1 2 Cr-modified Al 3 Ti intermetallic under high hydrostatic pressures ranging from atmospheric to 1 GPa pressure. Both encapsulated and non-capsulated specimens were tested. There was a significant increase of deformability of the material both in compression and tension tests under pressure in the case of encapsulated specimens. Nearly the same effect was observed in the case of non-capsulated samples in compression tests but it was insignificant in tension tests. The in-situ acoustic emission (AE) investigations carried out under pressure and microscopic studies conducted on the deformed material afterwards showed that the deformation process of the material under pressure is controlled by two mechanisms of deformation, plastic and cataclastic ones. The difference in the compressive and tensile properties of the material under pressure was explained by the influence of pressure on the cataclastic mechanism which is strongly affected by pressure because the pressure delays both the process of microcracks growth from nuclei and the process of their propagation. AE monitoring allowed to determine both transformations from pure plastic to cataclastic deformations and from stable cataclastic deformation to catastrophic fracture of the material. Analysis of the amplitude distribution of AE signals showed that the pressure also diminishes the failure process of the material.

Verbal commands as discriminative stimuli in domestic dogs ( Canis familiaris)

Domestic canids now have more uses than as pets and hunting partners. For example, humans have found them useful in the detection of drugs, as companions (e.g. those used in therapy for the mentally handicapped), and as aids to the physically handicapped. In this study, three dogs were used as subjects in five separate experimental tasks to test the abilities of these animals for increased usefulness as service dogs for the handicapped. The tasks included retrieving a particular wooden object in a three-choice situation as requested by the handler, locating the same objects at varying heights, retrieving the objects from behind a barrier, retrieving the objects when replaced by plastic ones, and returning to the handler without an object when the requested item was missing from a group of three presented objects. All three subjects were able to complete all five experimental tasks at a correct performance level of 83% or above (range 83–92%). In addition, their performances were comparable to those which have been studied in other (non-human) species. Thus, in this study, the dogs showed that it may be possible for humans to increase the difficulty of tasks required and, hence, the usefulness of domestic dogs as aids to the handicapped.

Environmental response of Galium palustre s. lat. in a coastal area in Central Sweden

Galium palustre s. lat. is a polymorphic taxon. The differences in morphology are correlated with the level of ploidy, but there is also a certain amount of phenotypic plasticity. The plasticity probably contributes to this taxon's successful colonization of a wide variety of habitats. The amount of plasticity was studied for plants from different kinds of habitats in Sweden, both for diploids (G. palustre s. str.) and octoploids (G. elongatum), which were cloned. This cloned material was then transplanted to three different localities in Sweden: a sunny exposed sea-shore, a ditch, and a shady alder swamp. The general pattern of morphology was similar for all material, independent of its origin and level of ploidy, with smaller plants (smaller in several vegetative characters) and a more abundant flowering on the exposed seashore than in the ditch, and the largest plants with a fairly sparse flowering in the alder swamp. The octoploid plants originating from the wooded wetland are the least plastic ones but are very variable within the localities. G. palustre var. balneum shows a similar variation pattern as the others, but there are also genetically fixed differences in some characters between it and G. palustre var. palustre. The changes in morphology of the plants in the different localities occur fairly rapidly (in one month), although the differences are more spectacular one year later.

A hematologist's view of contrast media, clotting in angiography syringes and thrombosis during coronary angiography

While ionic contrast media (CM) are stronger anticoagulants and antiplatelet agents, both nonionic and ionic CM retard clotting, fibrinopeptide A generation and platelet aggregation (at least by BornO'Brien aggregometry). Thus, nonionic CM do not cause clots and thrombi. Rather, the driving force for clot or thrombus formation, when it occurs, is blood contact with and activation by the foreign surface of a syringe or catheter itself. A marked enhancement of clotting by glass syringes in comparison to plastic ones supports this view. Blood in any syringe or catheter, therefore, will clot more slowly in the presence of nonionic or ionic CM, the inhibitory effects of the latter being more profound. With respect to models of thrombosis at sites of vascular injury or stenosis, the antithrombotic effects of CM may either be transient owing to the dynamic nature of blood flow (local endothelial cell denudation model), or as in the case of ionic CM, actually to enhance local platelet aggregation (stenosis model). In these situations, preservation of the antithrombotic functions of endothelium with nonionic CM may be quite critical.

Pseudoepidemic of Urinary Tract Infections due to Trichosporon beigelii

AbstractDuring the period April, 1985 to March, 1986, Trichosporon beigelii was isolated from the urine of 15 intensive care unit patients. All of these patients had Foley catheters in place at the time of T beigelii isolation. None of them had urinary tract infections on admission, and it was initially felt that this organism was a source of infection in these critically ill individuals. Subsequent investigation revealed this to be a pseudoepidemic secondary to contamination of the urinary catheter drainage system. Urine obtained by gravity drainage from the outlet port of urimeters yielded growth of T beigelii, whereas urines obtained concurrently from the proximal tubing sampling port were negative. T beigelii was isolated from the drainage port as well as from various items used in the collection and sampling of urine specimens. It is felt that these items were the source of perpetuation of this pseudoepidemic due to the repeated contamination and colonization of the distal portion of the urine catheter collection system. In-services to nursing and housekeeping personnel in the proper collection of urine specimens and cleaning of potentially contaminated items, the replacement of metal urine graduates with disposable plastic ones and increased monitoring of personnel's activities stopped the outbreak abruptly.

Pseudoepidemic of urinary tract infections due to Trichosporon beigelii.

During the period April, 1985 to March, 1986, Trichosporon beigelii was isolated from the urine of 15 intensive care unit patients. All of these patients had Foley catheters in place at the time of T beigelii isolation. None of them had urinary tract infections on admission, and it was initially felt that this organism was a source of infection in these critically ill individuals. Subsequent investigation revealed this to be a pseudoepidemic secondary to contamination of the urinary catheter drainage system. Urine obtained by gravity drainage from the outlet port of urimeters yielded growth of T beigelii, whereas urines obtained concurrently from the proximal tubing sampling port were negative. T beigelii was isolated from the drainage port as well as from various items used in the collection and sampling of urine specimens. It is felt that these items were the source of perpetuation of this pseudoepidemic due to the repeated contamination and colonization of the distal portion of the urine catheter collection system. In-services to nursing and housekeeping personnel in the proper collection of urine specimens and cleaning of potentially contaminated items, the replacement of metal urine graduates with disposable plastic ones and increased monitoring of personnel's activities stopped the outbreak abruptly.

Dolomite versus Limestone Habitats: a Study of Ionic Accumulation on a Broader Floristic Basis )

Limestone and dolomite are widely distributed substrates in Hungarian Middle Mountain-Range. The paper deals with differences in ionic accumulation of plants growing on the rocks mentioned. The 20 species (belonging to 17 families) growing on both kind of rocks differ significantly respecting Ca, Mg concentration and Ca/Mg ratio. The similarity of the same were expressed also on the basis of 11 element content. Displaying the results on a dendrogram, a group of “conservative” species (so: all the monocotyledonous ones) could be identified. In this case the concentration of components were not essentially modified by the difference in rock-type. Opposed to them are the plastic ones (Melittis grandiflora, Chrysanthemum corymbosum, Viola cyanea, Stachys recta, Geum urbanum) . Almost for all the species analysed a marked increase was found in values of concentration of both calcium and magnesium in autumn, compared to those obtained in spring. The obligate dolomite-plants did not prove to be “magnesium accumulators”.

変位測定方式の超微小硬度計

A new type of ultra-micro hardness tester has been developed in order to obtain precise indentation hardness of thin films and brittle materials. A differential coil with an accuracy of 0.01 μm is used in measurement of indentation depth instead of width. Electromagnetic force generated by applying an electric current to force coil is utilized for loading to a specimen, and so indentation hardness at a load of 9.8 × 10-5 N {10 mgf} can be obtained. Indentation test is automatically performed according to the program in microcomputer, and increasing load and indentation depth can be instantly recorded during the test. Use of microcomputer enables value of load and loading speed to be set over a wide range. A new method of finding out the surface of specimen is devised and experimentally confirmed. The indentation test in a few materials shows that the displacement of the indenter during loading is divided into the elastic and plastic ones with a high accuracy.

Semiótica del discurso y texto plástico: del esquema textual y la construcción imaginaria

The authors make the transposition of a semiotic theory of poem, consisting of the traditional semiotic levels, to the theory of the plastic text, in such a way that the absolute homology between all the processes of artistic communication like the plastic ones and the literary ones in proved, distinguishing the level of literarity as conventionalized pragmatic option and the level of poeticality as value based on the effects of the imaginary activity and communication. The authors examine examples of the Spanish modern painting.

The Baermann technique for estimating Protostrongylus infection in bighorn sheep: effect of laboratory procedures.

The modified Baermann funnel technique was evaluated to determine the effects of time of baermannization, fecal preparation, type and size of funnel, and type of filter on the number of first stage larvae of Protostrongylus spp. recovered from feces of Rocky Mountain bighorn sheep (Ovis canadensis). More larvae were recovered when fecal pellets were baermannized for 24 hr compared to 8 hr, and when feces were crushed than when left intact. Use of small funnels resulted in the recovery of more larvae per gram of feces than larger funnels, and glass funnels more than plastic ones. There was no difference in recovery of larvae between cheesecloth filters and cellulose filters.

Comparative evaluation of treatment of acute caries with inlays and fillings

Based on the registration of cases of secondary caries and loss of fillings 15-18 months after treatment, a comparative assessment of treatment with inlays and fillings in acute forms of caries was carried out. It was found that replacing carious defects with inlays is more effective than replacing them with fillings and that inlays made of chromium-cobalt alloy are more durable than plastic ones.

A Mechanical Model for The Stress-Strain Behaviour of Normally Consolidated Cohesive Soil

ABSTRACT A mechanical model on the stress-strain behaviour of normally consolidated cohesive soil is presented in this paper based upon the experimental results. Theoretical equations are derived based on the theory of elastoplasticity. Time effect is not taken into consideration. In the analysis, strain increment is divided into two components, i. e., elastic and plastic ones. The plastic component in strain increment is further divided into two components termed here as ƞ-component and p-component. These components of plastic strain increment occur due to effective stress increments in the directions of constant mean effective principal stress and constant stress ratio, respectively. Corresponding to two components of plastic strain increment, two sets of plastic potential, yield function and hardening function are proposed, and nonassociated flow rule is formulated. The strain increments due to the effective stress increments in various directions are calculated by this theory. The model thus obtained for the stress-strain behaviour of soil reasonably explains the dependency of the direction of plastic strain increment on that of effective stress increment. This model is applied to the analyses of triaxial drained shear tests along various stress paths and satisfactory result is obtained. The stress-strain behaviour by this model is compared with those obtained by theories by Roscoe et al. (1963, 1968) and Calladine (1971). Discussion on the stress-strain behaviour of soil predicted by these theories including the author’s one is given.

Plastic deformation around crack and fracture criteria: A review

A review, from the fracture mechanics viewpoint, of up-to-date data on plastic deformations around cracks and their role in crack propagation is presented. The review covers both theoretical studies carried out on the basis of continuous and discrete solutions of the corresponding elastic—plastic problems and experimental ones on defining plastic zones produced in the vicinity of cracks. Much attention to the papers on constructing fracture criteria with taking account of plastic strains is given.

Rate-dependent transient extrusion

Plane strain slip line field solutions are developed for deformation at the edge of a cylindrical billet when this is backward extruded to form a thin-walled cup. The extrusion pressure for a perfectly plastic material is then derived assuming homogeneous compression in the centre of the billet. A geometric factor, derived from the slip line field, is identified which permits the extrusion pressure to be determined for a nonlinear viscous material. Theoretical results agree well with recent experimental data on back extrusion of highly rate-sensitive superplastic alloys. It is shown that an apparent steady state exists in the process and that extrusion pressure increases with ram speed with a rate index approximately equal to that of the material. The punch profile shape has a greater effect on extrusion pressure for viscous materials than for perfectly plastic ones. The method of analysis appears to have a generality beyond the particular process considered and may be used to optimize extrusion equipment designs.

スタンプ圧入法による岩石の機械的性質の測定とそれの岩石の掘さく性との関係

Stamp penetration tests are carried out on rock samples of 8 species. Small cylindrical bars are used as stamps with sectional area of 3, 5, 10 and 20mm2. Stamps are forced into rock samples by a hydraulic press and force-displacement diagrams are recorded.Some mechanical properties of rocks are obtained from tests: these are yield value, hardness, plasticity coefficient, Young's modulus and specific work for distintegration of rock. Rocks are easily divided into brittle ones and plastic ones by the behavior of disintegration. Mechanical properties obtained by this test are correlated with compressive strength of rock and drilling performance with three cone bits.

Stiffness And Deformation Of Asperities In ARough Contact

In rough contacts the load is transmitted through the micro-contacts generated the interactions between the asperities. These micro-contacts are submitted by pressures and important stresses appear in the superficial layers close to the surface which lead to plastic deformation of the asperities. In our experimental work, we study the contact between a rough surface and a flat supphire. The samples used are Nickel electroformaging with quasi-sinusoidal roughness. The elastic and plastic parts of the deformation process of the roughness are determined, the experimental apparatus is composed of the loading system and an interferometric microscope in order to measure deformations. The values of the elastic deformation are compared to the theoretical results and the plastic ones with those obtained by using a profilometer coupled with the computer. Finally we deduce the asperity stiffness which are compared to those of the bodies. The results show the primary loading. The interacting asperities are loaded as well as the bodies. Then the elastic deformation and the stiffness are the main functions of the roughness' slope ( ratio of the asperity height to the wavelength ( Rt /1)). The asperity stiffness is very high compared to those of the bodies.

Equipment for gynaecological smears (DTB August 19, 1966 p. 66) - amplification

Arnold R. Horwell Ltd supply wooden Ayre Cervi-Scrapers made by Clay-Adams Inc (standard, 10/- per 100 for 500; special, for the enlarged cervix, 14/- per 100 for 500), and plastic ones costing 27/6 per 100. They also supply accessories for fixing, staining and mailing specimens.

A Study on the Deformation Theory of Plasticity in a Rotating Disc

It is a question yet to be studied whether the deformation theory may be used reasonably instead of the flow theory for the calculation of stresses and strains in a plastically deformed rotating disc. In this paper, the question is solved for a disc, which rotates at a speed that increases with time. At first the conditions, under which both theories give the same results referring to such a rotating disc, were studied based upon the theory of Ilyushin, and from these conditions it was deduced that the deformation theory was applicable to discs except partially plastic ones, which have elastically and plastically deformed regions. Secondly, methods to calculate stresses and strains in a partially plastic rotating disc by applying the deformation and the flow theories were developed, and the calculated results by those methods gave a fairly good coincidence with each other ; it shows that the deformation theory is applicable also to a partially plastic rotating disc.

Metallic Grating Replicas as Internal Standards for Calibrating Electron Microscopes

It was shown earlier that plastic grating-replicas mounted upon eighth-inch specimen screens were practical internal standards and that they could be accurately calibrated independently by spectroscopic means. Metallic replicas of diffraction gratings have been made by a direct-stripped method. These can still be direct-stripped easily and without damage to the original grating, and the optical quality of these pre-shadowed all-metal replicas is better than that of the plastic replicas. Because of their superior optical properties, the spacing can be determined spectroscopically more conveniently and with greater accuracy. In addition, the metal-gratings are more stable than the plastic ones. The electron microscopy of the metallic replicas and the accuracy and constancy of their magnification measurement is discussed.

SOME NOTES ON THE NATURE OF CLAY, II*

ABSTRACTThe drying shrinkage curves were accurately determined for a number of clays Some clays show a secondary shrinkage and Other finely divided The shrink and other finely divided substances. others do not. The latter are generally the less plastic ones. Other finely divided materials beside clay may show considerable plasticity, e.g., ferric oxide. age curves give an insight into the nature of the surface film on the clay particles.