Solvent Action Research Articles

On the very rapid enhancement by D2O of the temperature-tolerance of adult Drosophila.

Deuterium oxide, D(2)O, increases the temperature-tolerance of Drosophila pseudoobscura when it is administered to adult flies as a sucrose solution. The effect is very rapidly exerted; it is detected within 10 min after the flies have a brief (10 min) opportunity to drink. This increased resistance to heat-death surely implies an increased resistance of macromolecules to thermal denaturation. D(2)O is known to exert such an effect on in vitro protein solutions. The speed with which the increased stability develops clearly implicates a solvent action of D(2)O, and is most easily understood if the effect is traceable to enhancement of the hydrophobic interactions which contribute to conformational stability. The increased strength of deuterated hydrogen bonds cannot be excluded however. The possible bearing of these results on the hypothesis that D(2)O always increases the period of circadian oscillations by "diminishing the apparent temperature" is briefly considered.

Subsidence sinkhole at Runjh (Himachal Pradesh, India)

The sinkhole at the Runhj village in Himachal Pradesh, India, is the first reported occurrence from the Himalayas. It is situated in the Precambrian (?) basic volcanic rocks. The present study has revealed that the subsidence was caused due to the solvent action of subsurface water on salt, occurring on the sub-thrust side of the basic volcanic subnappe with the consequent removal of support affecting the ability of the roof to sustain the lithostatic load. This ultimately resulted in the formation of catastrophic sinkhole of cylindrical type.

The alkaline halides in the “carrier distillation” process in U 3O 8 matrix: Thermochemical reactions hypothesis in the evaporation mechanism

The action mechanism of the alkaline halides in the carrier distillation process has been studied. The temperature data in the anodic charge allow to consider the alkaline carriers as melted; a solvent action of the carrier salt in respect to the oxide impurities contained in the U 3O 8 matrix is supposed. The possibility of some thermochemical reactions in the anodic cup has been evaluated; the reaction products, formed during arcing, have been identified by X-ray diffraction analysis. The X-ray diffraction data and the thermodynamic calculations generally are in rather good agreement.

Gash-Breccias of South Pembrokeshire: Fossil Karstic Phenomena?

The paper records the results of mapping on a scale of I: 2500 of the gash-breccia pockets occurring within the Carboniferous Limestone Series of the Pembroke peninsula. Hypotheses for the 'derivation of these deposits through the medium of major cavern collapse or as former 'open-sky' scree accumulations are discussed. It is concluded, however, that the gash-breccias were tectonically produced in the first instance with preferential solution and limited collapse merely providing the finishing touches to the process of brecciation. It is suggested that some of the gash-breccias may be mid-Tertiary rather than Triassic in age. DURING the past two decades both geologists and geomorphologists have studied the nature and origin of the preglacial materials which occupy pipes and larger cavities, or otherwise disrupt the continuity of the normal bedded sequence, within the Carboniferous Limestone Series. Detailed surveys of such deposits have been undertaken in the Vale of Glamorgan,1 along the North Crop of the South Wales coalfield,2 in the Mendip-Bristol region,3 in north-east Wales4 and also in the Peak District.5 Perhaps the most clearly discernible deposits of this type to be found in the British Isles are the gash-breccias, long assumed to be of Triassic age, occurring within the cliff sections of the Pembroke peninsula. Here the detailed structure of individual pockets of gash-breccia is clearly revealed because of their common red-brown or pink colour, contrasting sharply with the prevalent greys of the Carboniferous Limestone. Prior to the present study no detailed examination of these gash-breccias had been made since that of E. E. L. Dixon on behalf of the Geological Survey.6 Dixon postulated that the gash-breccias had been derived by the solvent action of underground waters and the subsequent partial filling of caverns in the Carboniferous Limestone by the collapse of their walls and roofs. This view has been widely quoted by later writers, for example, by J. Pringle and T. N. George7 and J. Challinor.8 In the following account, Dixon's hypothesis is questioned; after considering other possible origins, it is suggested that the gash-breccias are in large measure of tectonic origin. Solution appears to have been preferentially concentrated along distinct shatter belts or at nodal intersections of fractures. While many of these disturbed zones are a direct result of the Armorican orogeny and were subsequently subjected to solution with some minor degree of collapse during Permo-Triassic times, others seem to be of later date and possibly of mid-Tertiary age. GEOLOGICAL BACKGROUND The gash-breccias of south Pembrokeshire are found only within the Carboniferous Limestone Series of the Pembroke peninsula and its outlying islands; they have not been recorded in the narrow outcrop of this formation which fringes the northern limits of the

The solvent action of sodium hypochlorite on pulp tissue of extracted teeth

In a study involving the mesial root canals of extracted human molars, sodium hypochlorite was found to be more effective than normal saline solution in dissolving pulp tissue and in cleaning the wider areas of the canals.

Effect of water‐binding agents on the catalyzed oxidation of methyl linoleate

AbstractAutoxidation of methyl linoleate was studied in model systems containing added metals and different water‐binding agents including cellulose, dextran and glycerol. In all systems, addition of water was increasingly antioxidant up to a critical level of water activity, above which further additions promote oxidation. The specific level of water activity at which oxidation rates are minimal and the water contents at this critical activity depend on the composition of the system. Results of the present study and much of the conflicting data in the literature can be explained as follows. A small amount of water is tightly bound to polysaccharides and does not affect lipid oxidation. Additional amounts of water are antioxidant because of their ability to hydrate metallic catalysts and to form hydrogen bonds with hydroperoxides. At high water contents the water's solvent action mobilizes catalysts, thereby overcoming the antioxidant effects. The present study indicates that water bound to glycerol is still capable of mobilizing catalysts. Depression of water activity by addition of agents such as glycerol has different effects on oxidation than does depression of water activity by other means. Interaction between the effects by system composition and water activity must be considered when either is varied to maximize storage stability of foods

Comparison of effects of tap water and slurry water on gypsum casts

E xcept for restorations made directly, one or more prerequisite stone casts generally are required for diagnosis, treatment planning, and fabrication. Therefore, the cast is a direct link between the clinical phase of treatment by the dentist and the technical phase in the laboratory. It is axiomatic that the cast should accurately reproduce the desired oral structures for the treatment to be a success. However, cast accuracy often is compromised by the solvent action of water. A dimensional change can occur when the cast is rinsed or soaked in tap water prior to the addition of stone for the base, as in 2 stage cast pouring techniques. The cast surface must be wet before it is placed on a model trimmer to prevent the slurry being spattered from sticking to the cast and to facilitate trimming and cleaning. Casts also are wetted prior to mounting on an articulator and at the time they are duplicated. Gypsum casts are soluble in water,ly 2 and their dissolution is increased if a stream of water is directed against the cast, as when it is placed under a faucet. Any dimensional change caused by the solvent action of water should be avoided if the cast is to be acceptable. One method of reducing the likelihood of damage is to saturate the water with calcium sulfate before rinsing or soaking a cast .I, 3l 4 The purpose of this investigation was to compare the effects

A new photoelastic method for evaluating durability of plastics

AbstractThis work was undertaken to measure quantitatively the quality change and crack development caused by degradation of plastics with the new photoelastic scale (P scale) using split circular ring‐type specimens (C specimen). For an example, a polycarbonate specimen was used under various conditions—photodegradation, thermal degradation, solvent cracking, solvent action, and alkaline degradation. The results indicate that this method is useful for evaluating durability of plastics, and a merit of the method is to provide quick, convenient, nondestructive means of measurement with simple equipment. Besides, this C specimen is easily deflected by a spring plate with two holes. Therefore this method is also applicable to the investigation of effects of deformation on various degradations of plastics.

The effect of flake size on the composition of graphite ferric chloride

A method of preparing stage 1 graphite ferric chloride with 97 per cent of the theoretical composition of C 6.1FeCl 3 is described. The solvent action of acetone on the product has been shown to completely empty a certain fraction of the spaces. This fraction is a negative exponential function of the thickness of the original flake of graphite. Various theories to explain this are proposed and related to the general process of intercalation.

Studies on the mechanism of freezing damage to mouse liver using a mitochondrial enzyme assay: II. Comparison of slow and rapid cooling rates

Summary By comparison with a variety of other electron transport components, the succinate cytochrome c reductase complex was found to be particularly senstive to, and suitable for evaluating, freeze-thaw damage. The use of a variety of freezing procedures demonstrated loss of half the activity of this enzyme complex, with little variation, over a large range of freezing rates, from 1°C per min to those produced by quenching in liquid nitrogen and isopentane. Quenching in liquid propane, however, produced a marked additional increment of damage resulting in a total loss in enzyme activity of 80%. The basis for the excess damage produced by liquid propane is believed to be related to its cooling rate, rather than to any peculiar solvent action, because maximal damage is produced within a few seconds and is not increased upon prolonged standing in the medium, and because the excess damage can be prevented by prefreezing the tissue in other media.

Changes in the solvent and selective action of polar solvents with changes in the extraction ? Separation temperature

1. It has been shown that when a mixture of paraffin and aromatic hydrocarbons is separated by extractive separation with polar solvents, the solvent action and the selective action of the latter may change in or out of harmony with each other as the temperature is altered (i.e., they can change in the same or opposite directions). They alter in different directions at high solvent to hydrocarbon mixture ratios, and in the same direction at low values of this ratio. The line of demarcation between the parts where the solvent and selective actions of the solvent are respectively out of and in harmony with each other on the liquid phase equilibrium triangular diagram for a three component system P-A-S is the critical solution point curve (extraction). 2. The extraction separation of hydrocarbons (e.g., an oil) with small amounts of polar solvents should be carried out at the lowest possible temperatures.

Applications involving the iodide ion

Abstract The effect of some complexing agents on the potential end point breaks in titrations of iodide with mercury(II) is studied. Iodide and complex ions (EDTA and CDTA) are determined simultaneously. The slight errors involved, are attributed to the solvent action of EDTA or CDTA on the precipitated mercuric iodide. In almost all cases the end points indicating iodide are stoichiometric, though the corresponding inflections are smaller than those obtained in absence of complexing agents; the decrement is dependent on the concentration of the complexing agent. Trials to analyze simultaneously binary and ternary mixtures of silver plus a variety of cations, which form stable complexes with EDTA were successful. A correction procedure is adopted to minimize the observed errors.

Histochemistry of myelin. VI. Solvent action of acetone on brain and other lipid-rich tissues.

The solvent action of acetone on frozen sections of brain and other lipid-rich tissues has been assessed by quantitative and chromatographic techniques. Under these histochemical conditions, acetone extracts free and esterified cholesterol, triglycerides and free fatty acids. Lecithin is not significantly extracted, while cephalins and sphingolipids are insoluble.

Mécanismes de rupture de la liaison carbone-ðain par les halogens I. Substitution électrophile sur carbone saturé

The reaction between halogens and tetraalkyltins is strongly influeced by the dielectric constant, the polarisability and the nucleophilicity of the solvent. These three aspects of solvent action are relatd to the ability of tin to make use of its empty 5 d orbitals: the «Sn polarisation, enhanced by the pentaco-ordination of the metal, governs the reactivity of the alkyl groups attached to it, appropriate attention being given to the incursion of steric effects. In polar media, the solvent itself acts as the nucleophilic catalyst and the reaction is best described by the following scheme ▪ In less active solvents, the halogen molecule plays the role of nucleophile in a predetermining step the most likely mechanism may be written as follows: ▪

The effect of phosphate solutions on the denaturation of frozen cod muscle

SummaryThe effect of treating cod fillets with phosphate solutions prior to freezing was studied. Little influence on subsequent denaturation of the cold stored material was found, as measured by protein extractability in dilute salt solution. However, the treatment invalidated the cell fragility method by producing very low values. Electron microscopy showed that these were the result of the solvent action of the phosphate solutions, which removed some of the protein from the myofibrils and made the cell fragility homogenate correspondingly less dense. Some of the dissolved protein was shown to be deposited on the surface of treated fillets, and it is the resulting film which probably seals the fluids in the fillet and causes the well‐known reduction in thaw‐drip.

The influence of solvent composition on the rates of second-order nucleophilic substitution reactions in alcohol–water mixtures

The overall rates of substitution of a number of aliphatic and activated aromatic halides by various nucleophiles in alcohol–water mixtures have been measured in the region near 100% alcohol. The results, particularly the unexpected increases of rate with additions of water, are discussed in terms of three effects: the Hughes–Ingold theory of solvent action, the change of nucleophile to hydroxide in aqueous solvents, and the proposed progressive dissociation of ion-parts of the sodium salts of anionic bases in more aqueous solvents.

A toxicologic study of dimethyl sulfoxide

The acute oral and intravenous toxicity of dimethyl sulfoxide (DMSO) was determined in mice and rats. Anemia and peritoneal inflammation were the main complications noted when rats were given a series of 24 intraperitoneal injections. No fatalities occurred in dogs that received a series of 24 daily intravenous injections of DMSO at dosage levels of 1.2 g/kg and below. Perivascular inflammation and local thrombosis resulted from the repeated intravenous administration of undiluted DMSO, but these reactions did not occur when the material was adequately diluted before use. In addition, a reversible hemolytic anemia was noted in dogs that received repeated intravenous injections of DMSO. DMSO seems to have a relatively low order of systemic toxicity. It has excellent solvent properties and other characteristics that make it a useful solvent for the administration of waterinsoluble drugs. Because of its local toxic action, DMSO should be diluted before parenteral use. Unfortunately, this limits its usefulness somewhat because additions of even small amounts of water may drastically lessen the solvent action. From an esthetic standpoint, the characteristic odor of DMSO may be undesirable.

GLycol-EThanol-WAter (3:3:4); A SOlvent for SUdan BLack B STaining

AbstractThe previously used supersaturated 60% isopropanol method (Lillie 1954, p. 303) protected the more readily soluble lipids from the solvent action of 70% alcohol but precipitation of dye particles within and around sections is sometimes a disturbing complication (cf. Vlachos 1959). The propylene glycol method of Chiffelle and Putt (Lillie, p. 304) has been found to remove much of the birefringent lipid from the sections. Glacial acetic acid dissolves most tissue lipids except those of the solvent-resistant ceroid or lipofuscin type. While solutions in 60–70% acetic acid conserve ordinary fats well (Sills and Marsh 1959) their effect on the more easily soluble lipids should be further explored.

Gel permeation chromatography. I. A new method for molecular weight distribution of high polymers

AbstractPolystyrene gels crosslinked in the presence of diluents have been made in fine‐mesh bead form suitable for packing into chromatographic columns. A series of narrow molecular weight range polymer fractions was eluted through such columns with aromatic and chlorinated solvents. Effluent concentrations were detected and recorded by a continuous differential refractometer. The fractions were shown to be efficiently separated. Columns capable of separating adjacent polymeric samples of high molecular weight were prepared from gels crosslinked in the presence of large amounts of diluents having little or no solvent action on polystyrene. Smaller proportions of diluents and those with more solvent action yielded columns with lower molecular weight permeability limits. Such studies provided a unique quantitative view of the topology of the gels. They also demonstrated that rapid repetitive molecular weight distribution data can be obtained in this way on polymers for which solvents compatible with the gels are available.

Experimental Abrasion 5. Frosting and Defrosting of Quartz Grains

Frosting of quartz grains is thought to be due in minor degree to mechanical action (1) by wind and (2) by water, but mainly to chemical action (3) by corrosive solutions and (4) by alternate solution and deposition of matter, especially in desert areas. Defrosting under water is likewise a physico-chemical process involving incipient crystal growth or solution. These physico-chemical actions, in contrast with mechanical attack, affect the whole surface of the grain equally, even in deep indentures. The typical circular markings of 3-10 μ diameter described by Cailleux as percussion cones are shown to be diffraction images of the light source. They can be observed also on the etched surface (e.g., by hydrofluoric acid) of crushed quartz, while electron micrographs of frosted grains fail to show any circular pattern of a few microns in diameter. Because of the diffraction effect, the resolution of the microscope is insufficient to distinguish chemical and mechanical action readily. True percussion cones occur on a minor proportion of well-rounded large quartz grains. Roughly speaking, the diameter is one-fifteenth or less of the long axis of the grain. On pebbles and cobbles this ratio is one-tenth. Experiments on wind abrasion and defrosting confirm these conclusions. On the one hand, mechanical aeolian abrasion is limited to corners and edges. It results in a coarser finish than natural chemical frost. On the other hand experimental fluviatile transport does not defrost but tends to frost polished grains on their protruding parts. Dry rolling in a bottle produces an ideal polish on protruding parts. The action of dew is invoked as the cause of desert frost by alternate solution and deposition. The chemical frost (noted by Sorby, Tricart, and others) is evidently a result of solution, possibly combined with deposition. The mechanical frost of aeolian action is somewhat suppressed in the desert by the healing over by dew action. Mechanical frost, both aqueous and aeolian, and chemical frost can be removed under water by solution or deposition according to the nature of the water involved. Experimental defrosting of sandpapered alum crystals in a saturated solution strongly supports the latter deduction. Experimental solution can lead to a polished finish and to rounding. The important solvent action of sea water will be treated in a later paper. A distinction is emphasized between reaction solution, in which case regrowth by evaporation is excluded, and non-reaction solution, in which case regrowth is possible. It would appear that the latter process produces smoothly rounded, polished surfaces, whereas the former tends to etch and cause frosted finish. In a short note (Kuenen and Perdok, 1961) the main points of the present paper were already recorded.