Degrees Of Dilution Research Articles

Abrasive wear of filled and unfilled resins in vitro

The present investigation was initiated to evaluate the wear resistance of filled and unfilled resins which may be suitable for fissure sealing. Two commercial unfilled resins (Adaptic Glaze and Delton), three degrees of diluted composite (Adaptic diluted with Adaptic Bonding Agent) and undiluted composite (Adaptic) were studied. Abrasion was caused by 400-grit silicon carbide paper in a mechanical surface grinder. Ten specimens of each of the material samples were tested. The unfilled resins were abraded three to six times more readily than the composite samples. Undiluted composite was the most resistant, whereas samples of increasing degrees of dilution were abraded to increasing extents. However, even the most diluted composite, although very fluid, was at least three times more resistant than the unfilled samples. The results of this study indicate that adding inorganic filler particles to a resin, even in small amounts, greatly enhances the wear resistance of such materials.

Bond strength of composites applied to acid‐etched enamel

The adhesion to acid-etched enamel of a four-component composite, Concise Enamel Bond System, was studied. The composite was applied undiluted over an intermediate resin layer and diluted with different amounts of resin. Corresponding surfaces of contralateral premolars were used to ensure that the composite samples were tested on areas with similar enamel etch patterns. Eighty specimens were tested. The results of this study indicated that the adherence of undiluted composite to etched enamel surfaces was not improved by using an intermediate layer of low-viscous resin. Composite diluted with liquid resin had poorer adherence than undiluted composite. There was no difference in the results from two degrees of dilution.

Geochemistry and origin of phosphorite deposits from off Peru and Chile

Holocene phosphorite nodules sampled from the sea floor off the coasts of Peru and Chile have been investigated in order to characterize the deposits geochemically and to evaluate their mode of formation. Bulk chemical and mineralogical compositions of the phosphorite nodules reflect varying degrees of dilution of the phosphatic material, fluorapatite, by other authigenic minerals and various allogenic components. Examination with the scanning electron microscope of freshly fractured surfaces of nodules and small pellets separated from associated diatomaceous ooze suggests that the apatite formed authigenically as a direct chemical precipitate rather than by replacement. Surfaces of siliceous biogenic materials as well as some inorganic phases appear to be favored sites for apatite nucleation. The proposed model of phosphorite formation involves inorganic precipitation of apatite within pore waters of anoxic sediments and subsequent concentration of the apatite by physical processes. Oxidation of organic materials (mainly diatoms) during SO 2− 4 reduction is the main source of dissolved phosphate. Apatite precipitation is favored within the sediments by the high phosphate concentration in the interstitial waters, by the availability of suitable nucleation sites, and by diagenetic reactions that remove interfering Mg 2+ ions from the pore solutions. Concentration of apatite into indurated phosphate nodules is brought about by winnowing and reworking processes, possibly in response to a change in the sedimentary environment caused by eustatic sea-level fluctuations or tectonism.

Evaluation of the Theories of Rubberlike Elasticity Using Swollen Networks Crosslinked at Different Degrees of Dilution

Abstract A recently reported study described the preparation of elastomeric networks by crosslinking poly(dimethylsiloxane) chains in both the undiluted state and in solution. Measurements of the moduli of these networks in the unswollen state gave results supporting the theory of rubberlike elasticity developed by Flory and coworkers, rather than the corresponding theory due to James and Guth. These results were not entirely unambiguous, however, because of complications due to departures (“2C2 corrections”) from the expected elastic equation of state. Much of this uncertainty has now been removed by measurements of the moduli of such networks in the swollen state, a condition under which the effects of the 2C2 contributions are known to be minimized. These new results strongly support the earlier conclusion that the Flory theory is the more nearly correct. Nonequilibrium effects, as well as the 2C2 corrections, diminish upon incorporation of a diluent into the crosslinked network; similar decreases occur if diluent had been present during the crosslinking process, even if such diluent is removed prior to the stress-strain measurements. Analysis of these additional results suggests that the 2C2 correction cannot be entirely due to nonequilibrium effects.

Reynolds number in restricted movement of mineral grains

The authors determine the conditions of similarity for restricted motion of grains in a stream at constant velocity which are common with the conditions for free motion governed by the similarity rule of Reynolds. In the Reynolds number for restricted conditions, the characteristic parameter should be a linear quantity characterizing the thickness of the layer of liquid diverted by the body. In this case the relation between the coefficient of resistance ψre and the Reynolds number Re l for restricted conditions takes the form of straight-line graphs passing through points on the Rayleigh curve corresponding to ψ0 and Re0 for free motion of the grains. These relations permit us to take detailed account of the variation in the degree of mutual influence between the grains in relation to their hydraulic dimensions. The expression for restricted motion of grains, based on the relation ψre =f(Re l ), embraces the whole possible range of degrees of dilution of the grains and can be used in practical calculations.

Evaluation of the Theories of Rubber-like Elasticity Using Swollen Networks Cross-Linked at Different Degrees of Dilution

Abstract A recently reported study described the preparation of elastomeric networks by crosslinking poly(dimethylsiloxane) chains in both the undiluted state and in solution. Measurements of the moduli of these networks in the unswollen state gave results supporting the theory of rubberlike elasticity developed by Flory and coworkers, rather than the corresponding theory due to James and Guth. These results were not entirely unambiguous, however, because of complications due to departures (“2C2 corrections”) from the expected elastic equation of state. Much of this uncertainty has now been removed by measurements of the moduli of such networks in the swollen state, a condition under which the effects of the 2C2 contributions are known to be minimized. These new results strongly support the earlier conclusion that the Flory theory is the more nearly correct. Nonequilibrium effects, as well as the 2C2 corrections, diminish upon incorporation of a diluent into the crosslinked network; similar decreases occu...

Effects of Dilution on a Six-Element Synthetic Aperture

An investigation was made of the effects of dilution on a six-element synthetic aperture. The characteristics of both the spread function and the transfer function were obtained for several degrees of dilution. It is shown that small degrees of dilution result in a significant gain over the performance of a single element, whereas more dilute apertures are inferior for direct imagery.

Contribution to the estimation of aminotripeptidase activity in synovial fluid

An application of the colorimetric estimation of aminotripeptidase activity in synovial fluid is described, with respect to special features of this biological fluid. Suitable conditions, e.g. adequate degrees of dilution, buffer and pH of the reaction mixture were experimentally found. For the substrate GGG, a paper chromatographic method was elaborated, which makes it possible to estimate the enzyme activity also in small amounts. Methods applied to the study of aminotripeptidase activity in biological material are reviewed.

Kinetical Study of Hydrocarbon‐Nitrous Oxide Flames

AbstractA comparative kinetical study of flames burning in mixtures of nitrous‐oxide and different hydrocarbons has been made. It has been found that the mean molecular weight of the chain carriers changes with the nature of the fuel. A probable reaction mechanism requests the formation of alkoxy radicals which decompose more or less easily according to their structure. Concerning the apparent activation energy derived from burning velocities at different degrees of dilution with nitrogen, no systematic change with the nature of the fuel has been observed.

SODIUM, POTASSIUM AND CHLORIDE IN SELECTED HYDROIDS

Previous articleNext article No AccessJournal ArticlesSODIUM, POTASSIUM AND CHLORIDE IN SELECTED HYDROIDSH. BURR STEINBACHH. BURR STEINBACHDepartment of Zoology, University of Chicago, Chicago 37, Illinois Search for more articles by this author Department of Zoology, University of Chicago, Chicago 37, IllinoisPDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Biological Bulletin Volume 124, Number 3June 1963 Published in association with the Marine Biological Laboratory Article DOIhttps://doi.org/10.2307/1539482 Views: 4Total views on this site Citations: 1Citations are reported from Crossref © 1963 Marine Biological LaboratoryPDF download Crossref reports the following articles citing this article:D. A. Wright and J. E. Purcell Effect of Salinity on Ionic Shifts in Mesohaline Scyphomedusae, Chrysaora quinquecirrha, The Biological Bulletin 192, no.22 (Sep 2016): 332–339.https://doi.org/10.2307/1542726

Induced ionization in hydrogen‐oxygen flames

AbstractThe influence of small and steadily increasing amounts of hydrocarbons (C2H2 and CH4) on the ionization in stoichiometric H2/O2 flames at different degrees of dilution with N2 has been investigated. The appearance of abundant ions is observed even with small amounts of hydrocarbons. The ion formation is to be ascribed to a process of chemi‐ionization. On the contrary with sodium salt the ion production occurs according to a thermal process; the law of energy equipartition is obeyed although the concentration of the ions is more important in the combustion zone than in the burnt gases.

HE EFFECT OF SEMI-CHEMICAL WASTE LIOUOR ON THE AOUATIC LIFE

When the Edogawa mill of Honshu Paper Mfg Co. constructed SCP plant, the trouble of pollution occured.Therefore the effect of waste liquor on the aquatic life was investigated.“ Tolerance Limit-48hr ” or “ Effective Dose 50 %” was measured, using several degrees of concentration of waste liquor, diluted with fresh or sea-water.Aquatic life was, -(1) carp, killifish, gold-fish, scenedesmus.(2) Zoea lavae, tapes philippinarum, goby, green laver, etc.The result was as follows : -(1) Safety limit (TLm-48hr) × 0.1 (Aquatic Life Advisory Committee 1955) was × 6, 000 dilution ratio of SCP waste liquor.(2) Waste liquor, completely spread in the flow of the “ Edogawa ” river, was at least × 33, 000 degrees of dilution.

Electrolytic conductivity apparatus

Presents an apparatus that will demonstrate the conductivity of salts when fused in the solid state, in solution, and in various degrees of dilution.

Paramagnetic resonance in iron alums

Experiments on paramagnetic resonance absorption have been carried out on single-crystals of iron ammonium alum with different degrees of magnetic dilution. It is found that absorptions with | Δm | > 1 occur and that these have to be ascribed to the influence of crystalline electric fields. Agreement with theory is found on the behaviour of the absorption as a function of the angle between external also high frequency oscillating field. A sharp absorption peak at 1 3 of the central peak field strength is found and an interpretation is given. The discrepancy between the assumption of a cubic crystalline field, the known specific heats of the spin system and the paramagnetic resonance results is discussed.

The Influence of Certain Genetic Factors upon Eye Color in the Guinea Pig

Knowledge of the genetic factors which influence eye color in guinea pigs has developed parallel to the study of the inheritance of coat color. Castle and Allen (1903) showed that albinism in the guinea pig was due to a recessive factor ca, wh:ch greatly reduced the pigment in the skin, hair, and eyes. The allelomorphic series C, ck, cd, cr, and ca, representing degrees of albinotic dilution, was described by Wright (1915, 1923). He showed that the factor cr was responsible for the absence of red pigment in the coat, and for a certain translucence of the iris whiclh gave the eye a reddish gleam in strong light. The factor C represented the h!ghest degree of intense pigmentation in the hair and eye, while the factors ck and cd represented degrees of dilution intermediate between C and cr. Bogart and Ibsen (1937) recognized black and chocolate pigments as two different kinds of granules. They found both granular and diffuse pigments present in the hair, and they interpreted the actions of the factors in terms of relative amounts of diffuse and granular pigments in the hair. Following the work of Bogart and Ibsen (1937), Harman and Case (1941) studied the development and histology of the skin and hair in a number of genetic types of guinea pigs. They observed red granules in red hairs, and were able to explain the action of the extension factors in terms of the kind, rather than the amount of pigment granules in the hair. Genetic factors which have been studied primarily with regard to their influence upon eye color include the recessive factor p (pink eye) described by Castle (1912), and the recessive factor sm (salmon eye) studied by Gregory and Ibsen (1926). The factor p has a marked diluting effect upon the black and chocolate pigments of the coat. Ibsen (unpublished) has since shown that the factor sm has a slight diluting effect upon these pigments, and that both factors dilute red pigment to some extent. Sollas (1909) described the eyes of chocolate guinea pigs as ruby in 'color, indicating that they were more brownish than the eyes of black guinea

The Soil Solution and the Mineral Constituents of the Soil

Solutions were made by extracting the soils from certain of the Rothamsted plots on which wheat and barley had been grown for 60 years and upwards. Wheat and barley were grown in these solutions, which were renewed fortnightly. The comparative growth in the solutions was closely parallel to the growth of the crop on the plots in the field and corresponded to the composition of the solutions. The composition of the solutions as regards phosphoric acid and potash corresponded to the past manurial treatment of the soils and to the amount of phosphoric acid and potash they now show on analysis. Growth in the soil solutions agreed with the growth in artificial culture solutions containing equivalent amounts of phosphoric acid and potash. Growth in the soil solutions from imperfectly manured plots was brought up to the level of that in the solutions from completely manured plots on making up their deficiencies in phosphoric acid and potash by the addition of suitable salts. The phosphoric acid and potash content of the soil solutions was of the same order as the phosphoric acid and potash content of the natural drainage water from the same plots.Wheat grew as well as barley in the solutions of the wheat soils, and vice versâ. In a similar set of solutions from the same soils the growth of buckwheat, white lupins and sunflowers corresponded with that of wheat and barley. Boiling effected no alteration in the nutritive value of the soil solutions.In nutritive solutions of various degrees of dilution the growth of plants varied directly, but not proportionally, with the concentration of the solution, though the total plant food present in the solution was in excess of the requirements of the plant. When the nutrient solution was diffused as a film over sand or soil particles, as in nature, there was no retardation of growth due to the slowness of the diffusion of the nutrients to the points in the liquid film which had been exhausted by contact with the roots. Growth in such nutrient solutions forming a film over sand particles was much superior to the growth in a water culture of equal concentration, but the growth in the water culture was similarly increased if a continuous current of air was kept passing through it.

Studies of the processes operative in solutions. XXVIII.-The influence of acids on the rotatory power of cane sugar, of glucose and of fructose

It is shown in Part XXII of this series of studies that when cane sugar is hydrolysed in the presence of solutions of sulphuric acid of different concentrations, the ratio of the final value of the rotation of the invert sugar to the initial value due to the cane sugar becomes very considerably greater as the concentration of the acid is increased. The effect was attributed to an increase in the optical rotatory power of the sugars caused by the acid; from the fact that the ratio of acid to sugar was the same in most of the experiments, it was argued that the determining factor was the ratio of acid to water, the alteration in the rotatory power being due mainly to changes in the water. Judging from the results of preliminary experiments and the work of previous investigators, it was probable that the fructose was the sugar chiefly affected but that observed change in the above ratio could not be attributed to this cause alone. In the course of experiments recently carried out to determine the hydrolytic activity of benzenesulphonic acid at different degrees of dilution, data have been accumulated which confirm the results arrived at when sulphuric acid was used as the hydrolyst. Experiments have also been carried out to determine the effect of the acid on the rotatory power of cane sugar, glucose and fructose.

Preliminary Note on a Characteristic of Certain Chemical Reactions

In a paper, communicated to the Society in February 1897, the author drew attention to increase in electrical conductivity as a characteristic of photo-chemical action.This increase in electric conductivity may be explained by assuming that light acts either in the direction of increased conductivity, or as a disturbing agent on molecular systems having an inherent tendency towards rearrangements involving increased conductivity.It may be that both assumptions are correct.Since making this communication the author has been engaged in experimental investigation, undertaken in order to elucidate this subject further—more particularly in its chemical aspect.The behaviour of nitric acid with respect to light appeared especially suggestive. Nitric acid on progressive dilution with water becomes less and less subject to decomposition by light, until, as that dilution which corresponds to maximum conductivity is approached, the action of light seems to cease altogether, so that nitric acid at all dilutions greater than that corresponding to its maximum electrolytic conductivity appears to be unaltered by light. It seemed, therefore, desirable to investigate experimentally the purely chemical behaviour of nitric, hydrochloric, and sulphuric acids at different degrees of dilution with water. The investigation is now sufficiently far advanced to justify the communication to the Society, in this preliminary note, of some of the conclusions which have been arrived at.