The Russell Effect with Rubber

1934 ◽  
Vol 7 (2) ◽  
pp. 309-313
Author(s):  
Avan Rossem ◽  
J. H. E. Hessels
Keyword(s):  
Prolonged Exposure ◽  
Mercury Vapor ◽  
Acetone Extract ◽  
Sodium Bisulfite ◽  
Gaseous Products ◽  
Acetone Extraction ◽  
Vulcanized Rubber ◽  
Low Concentrations ◽  
Quartz Mercury

Abstract (1) The Russell effect from raw rubber, after exposure to light and air, depends on three factors: (a) smoke components: smoked sheet shows a strong Russell effect owing to the presence of these components; Para does not because it is prepared with a different kind of smoke; (b) tackiness: most crepes show little Russell effect, but prolonged exposure after acetone extraction causes concurrent increases in both the Russell effect and tackiness; (c) acetone extract: the extract shows a strong Russell effect, but this is scarcely apparent when it is present in the rubber. (2) The gaseous products that cause the Russell effect are decomposed or driven off at 80° C. (3) These gaseous products are not the same as those formed by treatment with ozone. (4) Antioxidants for raw rubber do not affect the Russell effect, but sodium bisulfite weakens it. (5) Mastication or mixing with sulfur alone has little effect, but mixing with diphenylguanidine, triphenylguanidine or hexamethylenetetramine plus sulfur, or with mercaptobenzothiazole alone, considerably weakens the Russell effect. (6) Vulcanized rubber (normally or overcured, or oxidized by aging) shows a very weak Russell effect; this effect therefore will not detect incipient oxidation or a tendency to oxidation. (7) Quartz mercury vapor lamps are not suitable for experiments on the Russell effect, because the results are complicated by the ozone formed around them. (8) Ozone, even in very low concentrations (0.01 per cent or less), causes a strong Russell effect in both raw and vulcanized rubber.

Studies of Hard Rubber Reactions. VI. Liberation of So-Called Free Sulfur and Changes in the Acetone Extract of Vulcanized Rubber by Repeated Extraction and Heating

1940 ◽  
Vol 13 (3) ◽  
pp. 598-603 ◽  
Author(s):  
Seiiti Numaziri
Keyword(s):  
Sulfur Compound ◽  
Acetone Extract ◽  
Acetone Extraction ◽  
Vulcanized Rubber ◽  
Rubber Product ◽  
Free Sulfur

Abstract 1. True Free Sulfur.—In the case of the pure rubber-sulfur compound, as shown in the graph, the quantity of true free sulfur liberated from the thermally active hard rubber product by 120 minutes' cure was generally a little greater than that from the thermally nonactive sample with 300 minutes' cure. During the whole course of the extraction and heating, there occurs a lowest point in the true free sulfur curve, which increases again. In view of this fact, liberation of free sulfur can not be attributed to the insufficiency of the acetone extraction but is probably attributable to depolymerization of the vulcanizate or the like. 2. Acetone Extract.—Although purified rubber was used, the corrected acetone extract due to the formation of resinous substances from the depolymerized or aged hard rubber product showed relatively high values at the beginning of extraction and heating. To some extent, the change in acetone followed a course similar to that of the true free sulfur.

scholarly journals Screening for Effects of Inhaled Nanoparticles in Cell Culture Models for Prolonged Exposure

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 606
Author(s):  
Claudia Meindl ◽  
Kristin Öhlinger ◽  
Verena Zrim ◽  
Thomas Steinkogler ◽  
Eleonore Fröhlich
Keyword(s):  
Prolonged Exposure ◽  
A549 Cells ◽  
Cytokine Release ◽  
Transient Effects ◽  
Particle Uptake ◽  
Particle Accumulation ◽  
Low Concentrations ◽  
Culture Models ◽  
20 Nm ◽  
Inhaled Nanoparticles

Respiratory exposure of humans to environmental and therapeutic nanoparticles repeatedly occurs at relatively low concentrations. To identify adverse effects of particle accumulation under realistic conditions, monocultures of Calu-3 and A549 cells and co-cultures of A549 and THP-1 macrophages in the air–liquid interphase culture were exposed repeatedly to 2 µg/cm2 20 nm and 200 nm polystyrene particles with different functionalization. Particle accumulation, transepithelial electrical resistance, dextran (3–70 kDa) uptake and proinflammatory cytokine secretion were determined over 28 days. Calu-3 cells showed constant particle uptake without any change in barrier function and cytokine release. A549 cells preferentially ingested amino- and not-functionalized particles combined with decreased endocytosis. Cytokine release was transiently increased upon exposure to all particles. Carboxyl-functionalized demonstrated higher uptake and higher cytokine release than the other particles in the A549/THP-1 co-cultures. The evaluated respiratory cells and co-cultures ingested different amounts and types of particles and caused small (partly transient) effects. The data suggest that the healthy cells can adapt to low doses of non-cytotoxic particles.

Studies on the Acetone Extraction of Raw Rubber

1935 ◽  
Vol 8 (4) ◽  
pp. 604-612
Author(s):  
Hidemaro Endô
Keyword(s):  
Acid Value ◽  
Acetone Extract ◽  
Water Bath ◽  
Acetone Extraction ◽  
Saponification Value ◽  
Alcoholic Potash ◽  
Saponifiable Matter ◽  
Acetone Extracts ◽  
Hcl Solution

Abstract (1) For the determination of the saponification value of the acetone extract, 20 cc. 0.2 N alcoholic potash is added to the extract and the flask is heated on a water bath for 60 minutes. It is then titrated with 0.1 N HCl solution, using phenolphthalein as indicator. (2) When the saponification values of the acetone extracts of 8, 16, and 24 hours are compared, the saponification value of the 8 hour extract is seen to be high, while those of 16 and 24 hour extracts are low. This indicates (a) that the 8 hour extract contains a higher percentage of saponifiable matter than the 16 and 24 hour extracts; (b) the quantity of rubber hydrocarbon which is dissolved in the acetone extract increases with increasing time of extraction, and (c) the acid value of the acetone extract decreases during the period of extraction from 16 to 24 hours. (3) Regarding the saponification values (R) of the acetone extracts of 8, 16, and 24 hours, similar remarks may be made as in (2) above.

scholarly journals STIMULATION OF CELLS BY INTENSE FLASHES OF ULTRAVIOLET LIGHT

1942 ◽  
Vol 25 (3) ◽  
pp. 431-444 ◽  
Author(s):  
E. Newton Harvey
Keyword(s):  
Connective Tissue ◽  
Ultraviolet Light ◽  
High Voltage ◽  
Mercury Vapor ◽  
Lethal Effect ◽  
Single Muscle ◽  
Oscillatory Movement ◽  
Quartz Mercury ◽  
Unicellular Organisms ◽  
Stimulation Of

A study has been made of the effect of sudden intense flashes of ultraviolet light, acting on a wide variety of cells and tissues, with special reference to stimulation. The flashes are obtained by a high voltage condenser discharge through a quartz mercury vapor sterilamp, using the method of Rentschler. The lethal effect of a single such discharge is widespread among unicellular organisms. Medullated nerves and whole muscles are not visibly stimulated, because of absorption by connective tissue. Single muscle fibers undergo immediate contracture in 50 per cent of the experiments. Nitella cells are stimulated, the effect depending on the dosage. Weak ultraviolet flashes slow or stop cyclosis reversibly. Strong flashes stop cyclosis reversibly with the appearance of a local or a propagated action potential. Very strong flashes kill the Nitella cells. The effect of single flashes on myonemes, oscillatory movement, ameboid movement, cilia, flagella, and bioluminescence is described in the text.

Studies on the Acetone Extraction of Raw Rubber. VII. The Time of Acetone Extraction of Raw Rubber and the Saponification Value of the Acetone Extract and Residue

1936 ◽  
Vol 9 (2) ◽  
pp. 308-310
Author(s):  
Hidemaro Endô
Keyword(s):  
Fatty Acids ◽  
Gradual Increase ◽  
Acid Value ◽  
Acetone Extract ◽  
Continuous Extraction ◽  
Acetone Extraction ◽  
Saponification Value ◽  
Saponifiable Matter ◽  
Acidic Compounds ◽  
Almost All

Abstract During acetone extraction of pale crepe, the free acids and saponifiable matter were extracted almost completely in 1 or 2 hours. The saponification value (A) had a tendency to decrease rapidly and to reach a minimum after 12 hours (in non-continuous extraction) or after 16 hours (in continuous extraction). The cause of the decrease of the saponification value (A) from the commencement of extraction up to the time mentioned is thought to be due to a gradual increase in the amount of extracted non-acidic compounds and unsaponifiable matter with increasing time of extraction, and to the neutralization of acids by other compounds, as by esterification. After reaching the minimum point, the saponification value (A) had a tendency to increase gradually. This increase is thought to be due to (1) a gradual increase of ester extracted, (2) the formation of acids by oxidation, and (3) the formation of free acids by decompositions of esters, though the last factor does not increase materially the saponification value. The change of saponification value of the acetone extract with increasing time of extraction is not due to any change in the type of compounds gradually extracted, but to a change in the acetone extract in the acetone solution during extraction. This is in agreement with the acid value. It was observed in a previous paper (III) that almost all of the free acids contained in pale crepe were extracted by acetone in 1 hour. But by extraction for 1 or 2 hours, a small portion of the saponifiable matter still remain unextracted. This remaining part could not be extracted even by prolonged extraction. It is believed, therefore, that the free fatty acids are dissolved in the saponifiable matter, and that the latter are dissolved in the rubber hydrocarbon. As the acetone extract is very labile, so far as the change of acetone extract is concerned, the acetone extract, whether it be dried or left in solution, should not be stored for too long a time. The results obtained by such long extraction by acetone as multiples of ten hours, as used by Whitby and Winn (J. Soc. Chem. Ind., 41, 336T (1923)), are thought to be quite unreliable.

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