Gel-like Material Research Articles

A fine-structural study of the pea downy mildew fungus Peronospora pisi in its host Pisum sativum

Downy mildew disease of the cultivated pea Pisum sativum L. caused by the fungus Peronospora pisi Sydow was studied in mature leaves and young shoots of the host plant. Particularly in systemic infections of young shoot tissue, a common occurrence was an extremely electron-opaque membrane-bound, hemispherical deposit extending through the host cell wall into the host cytoplasm. This material which abutted directly onto the intercellular hyphal wall was termed the penetration matrix. Its formation was apparently the result of a specific interaction between the host and obligate fungal parasite. Similar apparently solid or gellike material constituted the matrix surrounding the digitlike intracellular haustorium. This membrane-bound extrahaustorial matrix was present through the penetrated host cell wall and formed a relatively thick layer around haustoria in young shoot tissue, but was much thinner distally around haustoria in mature leaf mesophyll cells. An unusual, regularly arranged, tubular network of ribosome-free endoplasmic reticulum was occasionally found in the host cytoplasm in systemically infected shoot tissue adjacent to haustoria.

Phosphate fixation by ando soils different in their clay mineral composition

Abstract The phosphate fixation capacity at pH 4.5 and an equilibrium concentration of 250 mM phosphate was measured. The soil samples were divided into five groups according to their clay mineralogical composition. The first group soils contain opaline silica and allophanelike constituents, and some unidentified minerals, the second opaline silica and crystalline layer .i1icates, the third opaline silica and crystalline layer silicates with additional allophanelike constituents or aluminarich gel-like materials, the fourth allophanelike constituents, allophane and imogolite and the fifth crystalline layer silicates, allophanelike constituents and alumina-rich gel-like materials, plus some halloysite-like minerals, respectively. The first group soils had phosphate fixation capacities of 3,000 to 8,000, the second group soils 1,000 to 3,000, the third group loib 2,000 to 13,000, the fourth group soils 8,000 to 15,000 and the fifth group soil. 5,000 to 12,000 mg P2O5/100 g oven-dry soil, respectively. The fourth group soils in which allophane and imogolite predominated showed the highest phosphate fixation capacity. The fractions which dissolved from almost all soil samples by treatments with 6% H2O2 Na2S2O4-NaHCO2-Na citrate and 2% Na2CO3 were estimated to have very high phosphate fixation capacities (8,000 to 19,000 mg P2O5/100 g dry-matter), and there was not much difference among the soil samples examined. Iron and aluminum combined with humus, allophanelike constituents, alumina-rich gel-like materials and halloysite-like minerals in addition to allophane and imogolite contribute to the phosphate fixation of Ando soils.

Studies on spreadability of platelets

The spreading of blood platelets after adhesion was first observed by Eberth et al. (1885) and has been studied since by many investigators. The underlying mechanisms, however, are not known in many respects and there has been no report so far of its electron microscopic observation.PURPOSE: For making observation of the mode of normal platelet adhesion and spreading by scanning electron microscopy as well as to investigate morphological changes of spreading platelets in elected hematologic disorders.SUBJECTS: The mechanism of platelet spreading was investigated with specimens from healthy male adults, followed by comparison of the spreading of plateles from patients with C. M. L. or I. T. P.PROCEDURE: Platelets were allowed to spread on plastic plates by the method of Breddin and fixed after intervals of 5, 15 or 30 minutes for microscopic observation. Those from patients were fixed after 30 minutes of spreading. For electron microscopy, specimens were fixed with 1% glutaraldehyde and, after postfixation in 1% OsO4, they were dehydrated, dried and covered by the vacuum evaporation of carbon and metal.RESULTS: Mode of spreading—At 5 minutes of spread each platelet was found to have sent out one or two pseudopodia. When 15 minutes had elapsed the pseudopodia were found increasing in number and elongated to shape up a dendritic form. At 30 minutes, the platelet was spread to assume a discoid shape with the peripheral transparent hyalomere and the central portion consisting of a gel-like material. A series of scanning electron micrographs shows that, generally speaking, the platelet sends out pseudopodia which thereafter increase in number and extend to form dendroid structures with a subsequent formation of the hyalomere just like a membrane spreading around neighboring pseudopodia; the platelet thereby gradually spreads into an ellipsoid shape. An occasional platelet shows the formation of a clear zone by a sol-like outflow around the pseudopodia, followed by its confluence with the substance from the central portion to eventually make the platelet discoid. It was also noted that a platelet had a peripheral clear zone formed around it at as early as the initial stage of adhesion and thereafter appeared to continue spreading in all directions; it remains yet to be determined whether or not this represents the consequences of a rapid progress in platelet spreading in either of the foregoing two fashions. Platelets from patients—Most platelets from CML patients were found asteroid with incompletely spread peripheral dendroid structures. In ITP, platelets were ellipsoid and displayed remarkably active spreading; the central portion consisted of a gel-like substance with an irregularly uneven surface and with trabeculations around it.CONCLUDION: Blood platelets were observed to spread in three different modes, and this finding would be of significance as an aid to elucidation of the process of platelet adhesion. The observation also disclosed a remarkably striking difference in the morphology of platelet spreading between CML and ITP, suggesting likely abnormalities of platelet function in these conditions.

Configuration of cellulose trinitrate in solution

Cellulose trinitrate was prepared from cotton (Deltapine) under a variety of conditions and investigated in solution with ethyl acetate as solvent using the techniques of light scattering, osmometry and viscometry. The more mildly nitrated samples (e.g. 1 h at 20°C) exhibited downward curvature in the Zimm plots and a fractional precipitation experiment showed that this was due to the presence of large gel-like aggregates. Light scattering, viscometry, infra-red and ultracentrifuge measurements were made on the fraction of gel-like material and the effect of further nitration investigated. The possible nature of the aggregates is discussed. Light scattering measurements made on a mildly nitrated sample with this fraction removed yielded a straight line Zimm plot from which chain statistics similar to those found by other authors could be deduced. Samples obtained by more extensive nitration (2–25 h at 20°C) were considerably degraded but yielded straight line Zimm plots and osmotic pressure measurements showed the polydispersities to be low ( DP w DP n ∼ 1.3 ). Values of effective bond length, b, calculated from these Zimm plots (4.6 to 5.6 nm) were much larger than those found for the more mildly nitrated samples and those found by other authors. Also, in contrast to the results of other authors, second virial coefficients obtained by light scattering and osmotic pressure were found to be in fair agreement. The effect of gel-like material on measured second virial coefficients is discussed. It is suggested that the discrepancy in b arises because gel-like material remains in more mildly nitrated samples even after the larger aggregates have been removed by fractional precipitation. This material consists of particles denser than the single coils but of comparable or smaller size so that values obtained for the effective bond length are too low. The results of previous investigations on all the cellulosic polymers which have been investigated are discussed in the light of the present work with particular reference to the effect of gel-like material. It is suggested that the apparent disagreement between the conformational analysis of cellulose and experimental results arises from the presence of gel-like material in solutions rather than any fault in the molecular model.

Shear waves in unconsolidated sediments

The dynamic shear modulus of unconsolidated marine sediments is small but nonzero. Shear waves will propagate in the sediments, but only at very slow speeds. The compressional wave speed is increased as much as 5% by the nonzero modulus. As a suspension of clay particles settles and collects into a gel-like material, the dynamic shear modulus increases. This initial development of sediment frame structure has been observed by measuring shear wave speed. Several stages in the development process can be described from these results.

Relationships between the primary mineral and the clay mineral compositions of some recent andosols

Abstract Relationships between the clay mineralogy and the primary mineral association were studied on seventeen Andosol samples (<3,000 years old) collected from Aomori, Hokkaido, and Iwate. Opaline silica, allophane, and imogolite were predominant in the soils derived from volcanic ashes which contained practically no quartz, while opaline silica, crystalline layer silicates, alumina-rich gel-like materials, and allophanelike constituents were abundant in the soils which contained abundant quartz. There was no positive indication of the presence of allophane in any quartz andesitic Andosols. High contents of finely comminuted amphibole and mica in the quartz andesitic volcanic ashes suggested that the crystalline layer silicates are inherited and are not formed pedochemically from amorphous materials.

Glycogen Content of Honeybee Larvae Killed by American Foul Brood Disease

SummaryAqueous extracts from larvae killed by American foul brood disease (scales) contain a turbid, opalescent material, which was separated from the proteases by gel filtration on Biogel P-300, and from the spores by centrifugation. The purified, gel-like material was identified as glycogen by its solubility in a number of solvents, and by staining reactions and hydrolysis products. Quantitative estimations of glycogen content in individual scale samples gave a value of 3.32 ± 0.37 mg per 20 mg scale sample, or 17% by dry weight.

C 3A hydration

C 3A is hydrated with time and temperature as variable parameters. The solid hydration products were observed using the scanning electron microscope and determined by XRD. The heat development was followed by means of isothermal microcalorimetry. The first hydration product is a gel-like material with no detectable XRD lines. The hexagonal phases which follow have a better crystallinity when formed below than above room temperature. In the latter case distinct XRD lines are only obtained after some time. C 3AH 6 as single crystals or aggregates develops earlier at high than at low temperatures. The morphology of C 3AH 6 varies with hydration time and temperature. This sequence of reactions occurs slowly in suspensions if a small amount of C 3A is used. In pastes, and in suspensions if a larger amount of C 3A is used, C 3AH 6 is formed very quickly and no hexagonal hydrates were detected by XRD.

Relationships between the inorganic colloid and the parent material of some volcanic ash soils in Miyagi and Iwate Prefectures, Japan

Abstract Relationships of the inorganic colloid to the parent material were studied on 13 volcanic ash soli samples taken from Miyagi and Iwate prefectures. Allophane and imogolite were predominant in the soils derived from basaltic or andesitic ashes, while 2 : 1 and 2 : 2 type layer silicates, alumina-rich gel-like materials, and allophane like constituents were abundant in the soils of quartz andesitic ash origin. A randomly interstratified mineral of halloysite and 2 : 1 type layer silicates was found in the fine clay fraction of fairly well-weathered quartz andesitic ash soils. The clay mineralogical compositions of volcanic ash soils were distinguished from each other in terms of the petrological nature of their parent ashes.

Relationships between the petrological nature and the clay mineral composition of volcanic ash soils distributed in the suburbs of Fukuoka-City, Kyushu

Abstract A contrasting occurrence of clay minerals was found within a soil profile which was derived from volcanic materials in the suburbs of Fukuoka-city, Northern Kyushu. The soil profile is located on an isolated terrace, and the morphological characteristics of the soil correspond exactly to Andosols, so-called Kuroboku soils or Humic Allophane soils. The clay fraction of upper horizons of the soil consists largely of alumina-rich gel-like materials, gibbsite, and layer silicates such as chlorite and chloritevermiculite intergrades, while that of lower horizons is composed of allophane and gibbsite or halloysite. There was no positive indication of allophane in the upper horizons. Corresponding with the clay mineralogical composition, quartz is abundant in the fine sand fraction of the upper horizons, while the mineral is very scarce or none in the lower horizons, suggesting a close relation between the petrological nature of parent volcanic materials and the mineralogical composition of weathering p...

Channelblock Pilot-Area Application, Weyburn Unit, Saskatchewan

Abstract The results of treating a pilot area located on the east edge of the Weyburn Unit with Channelblock* are discussed in this paper. Channelblock is obtained by mixing polymer in low concentrations 0.05 to 0.1%) withwater and adding an "activator", which greatly changes the characteristics of the injected water to a gel-like material This gelled polymer gradually penetrates and adsorbs itself on the walls of the highly permeable streaks or fractures, thus diverting large quantities of water into tighter zones and resulting in a higher waterflood recovery. Introduction THE WEYBURN UNIT is situated in southeastern Saskatchewan and encompasses an area of approximately 100 square miles. The field was discovered in January, 1955 and was extensively developed during subsequent years by drilling 675 wells on 80-acre spacing (Fig. 1). A distinctive feature of this Mississippian Midale Beds pool and of other fields located in the same part of the Province is the presence of an anisotropic permeability system) with the major axis of permeability oriented in a northeast direction (Fig-2). This fracture system, which was first recognized an the basis of oriented fracture cores, has been clearly identified by waterflood performance. Oil accumulation in this stratigraphic trap is found mainly in the Midale Beds of the Charles Formation of Mississippian age. It is subdivided into two distinct lithological units; the lower is called the "Vuggy" limestone and the upper is called the "Marly" limestone (Fig 3). The Marly rock is a micro granular carbonate characterized by fairly uniform porosity and low permeability. The Vuggy rock is generally a microcrystalline, frag-mental limestone with extreme variations in pore size and in porosity- permeability distribution. Oil gravity varies with structural position from a low of 26 °API at the southern downdip limit to a high of 35.6 °API at the highest structural position to the north~ An aquifer of modest dimensions is generally present along the edges of the field. An inverted nine-spot injection pattern was selected for water-flooding this type of limestone reservoir because of the flexibility of this pattern, allowing for the conversion to a staggered line drive or a line drive when the on-trend wells along the fracture plane water out and the flood front moves toward the off-trend wells. Since the implementation of the waterflood injection scheme in June, 1964, the on-trend producers ha.ve generally shown early breakthrough ollowed by a rapid productivity decline, a sharp increase in water production and what appears to be a very short waterflood productive life. The flood performance of the off-trend and corner wells is essentially affected by their degree of stratification. This unfavourable waterflood performance has been substantially improved in a pilot "rea of the field by the use of Channelblock chemicals. It is the object of this paper to give a description of the treatment and a detailed presentation of the results obtained. GEOLOGY The Weyburn field is situated along the northeastern flank of the Wilnston Basin in southeastern Saskatchewan.

Selective Dissolution and Differential Infrared Spectroscopy for Characterization of 'Amorphous' Constituents in Soil Clays

AbstractPoorly crystalline inorganic materials were removed from soil clays of different origin and mineral composition by successive treatments with sodium dithionite, 2 % Na2CO3 and 0·5 N NaOH. Techniques are described whereby difference spectra representing the infrared absorption of the materials removed by the treatments can be obtained. These spectra indicate that the materials dissolved are related to the mineral composition of the soil clay. Dissolution of allophanes of different composition was only proved for two volcanic ash soil clays in which these dominated. Layer silicates, probably including kaolin, were dissolved from the clay fractions of the red-brown earth and krasnozem studied. In addition, alumina-rich gel-like material and gibbsite, but no allophanes, were dissolved from another volcanic ash soil clay in which gibbsite and layer silicates are present in considerable amounts.

The interaction of nucleated cells with anionic polyelectrolytes and inhibition of the interaction by pancreatic deoxyribonuclease

The interaction of nucleated cells with polyanionic electrolytes leads to the formation of gel-like material entrapping the cells. The interaction is time dependent and as it occurs polymer is absorbed to the cell. Addition of the combination of pancreatic deoxyribonuclease and Mg ion, both being necessary, results in the complete breakdown of the viscous gel. Trypsin or ribonuclease in the presence or absence of Mg ion has no effect on the gel. The simultaneous presence of deoxyribonuclease and Mg ion with cells and polymer results in the complete inhibition of the interaction between cells and polymer. Again, other enzymes are not effective in this regard. The cells that are protected from the effect of the polymer leak very little cytoplasmic protein and ribonucleic acid, and retain their viability in contrast to the cells in the gel treated with deoxyribonuclease.

Polymerization of butadiene in the presence of triethylaluminum and n‐butyl titanate

AbstractMeasurement of butadiene absorption at constant volume, and of polymer formation, indicated that the rate of polymerization was first order in monomer concentration, up to 1.5 mole/l., and also in initial total catalyst concentration, for given molar ratio of alkyl to titanium ester. The overall activation energy was 11.5 kcal./mole. A fast initiation, accompanied by the evolution of ethylene or a mixture of ethane and ethylene, a relatively slow propagation, and chain transfer to monomer, appeared to be the main steps of the reaction. Termination was essentially absent. Insoluble, gellike material was formed roughly at 20% conversion and was attributed to a random crosslinking, involveing very few crosslinks per molecule, or possibly trifunctional branching. The molecular weight distribution was very narrow. A polymer of over 80% in 1,2 units, having a predominantly syndiotactic structure and about 10% crystallinity, was obtained. In the absence of monomer, the catalyst components reacted rapidly to form complexes, accompanied by strong ethane evolution. A complex series of reactions leading to the possible formation of more than one active species was indicated. The active catalyst suffered bimolecular decomposition on prolonged standing. For optimal molar ratio of alkyl to ester of 5/1, the concentration of active species was estimated as having an upper limit of 4.8 × 10−6 mole/l.

Osmotic reversal of mitochondrial swelling

Previously published data 1,11 have been found consistent with the hypothesis that mitochodrial swelling is primarily the result of the penetration of the suspending solute. A relaxation of a contractile mechanism or the hydration of an internal gel-like material do not seem to be significant in this process. Since an osmotic swelling will be necessarily osmotically reversible, this question was re-examined experimentally. Swelling in sucrose and potassium chloride solutions, as well as those induced by thyroxine, were found osmotically reversible.

Physical properties of thymus nucleoprotein

1. 1. Nucleoprotein prepared by washing with dilute salt solution and extracting with water can be obtained mainly in the form of a highly aggregated gel-like material. 2. 2. The dispersed nucleoprotein obtained by several previous investigators is probably formed by enzymic degradation of the gel-like material.

Behavior of some alkali soap systems in organic solvents

1. 1. The behavior of sodium oleate, sodium stearate and sodium palmitate toward 40 different organic solvents has been examined. It is found that the soaps do not dissolve in most of the solvents at room temperature, but swell on heating and give clear mobile solutions near the boiling point of the solvent. On cooling these solutions, any one of the following phenomena takes place, depending upon the nature of the soapsolvent system: (1) the soap remains in solution, (2) the soap crystallizes out, (3) a pseudo-gel is formed, or (4) a true gel is obtained. 2. 2. It is observed, in general, that the amount of the gel-like material obtained, that is, the gelating capacity of the soap-solvent system, increases roughly with the boiling point of the solvent. 3. 3. The behavior of the soap-solvent systems giving rise to true gels has been examined with special reference to the degree of supersaturation. It is observed that, if the soap content is low, crystallization occurs when the hot soap-solvent system is. cooled. With an increase in the concentration of the soap, a pseudo-gel is obtained at first, and a true gel is formed only when an optimum concentration of the soap is reached. Further, the transition from the crystalline state to the weak precarious pseudo-gels, and subsequently to the typical stable gels, is effected by very gentle gradations in the concentrations of the soap in the system. 4. 4. The temperatures of crystallization and of the formation of pseudogels and true gels have been measured in the case of the three soaps in 16 different solvents. The zones of concentrations in which the soap exists in the three different states have also been determined.