Carbon Suspensions Research Articles

Electrophoretic Development of Electrostatic Charge Images from Colloidal Suspensions of Carbon

The physical parameters of colloidal carbon particles in an insulating liquid have been measured by several independent techniques. The particle size and charge, the Debye screening distance, and the interparticle distance are found and are used to interpret the electrographic development process (toning). The nature of the developed image depends upon the magnitude of the initial surface charge density and upon the time in the toning bath. The optical density for full development of an electrostatic charge image is shown to be proportional to the charge density in the image indicating that arriving particles overlap in a random manner. Measurements on the development process as a function of time shows that particles are being drawn out of the colloid in the intermediate range where both diffusion and mobility must be considered in determining the motion of the particles.

Polarography of carbon suspensions

Polarography of carbon suspensions

Polarography of carbon suspensions

The polarographic behaviour of activated charcoal and two other forms of carbon have been studied. Activated charcoal suspensions give rise to a high cathodic current peak which is greatly enhanced by stirring. The diminished current on each side of the peak is shown to be due to the inability of particles to make contact with the DME at potentials removed from the electrocapillary zero of mercury. This inability arises from a boundary layer effect, produced by vigorous movement of the mercury surface and the liquid in contact with it. The reducible groups on the charcoal surface can be reduced by sodium dithionite and also by bulk electroreduction. The cathodic current is then replaced on the polarogram by anodic current. The quantities of electricity, calculated from oscillographic recordings of current pulses for single charcoal particles, show a very high surface concentration of reducible groups. The form of the pulses and the quantities of electricity they represent are pH-dependent, suggesting participation of hydrogen ions in the electroreduction process.

Particle size from the optical properties of flocculating carbon dispersions

The reasons for the inapplicability of Mie theory to systems where the dispersed particles are aggregates of smaller primary particles are discussed. It is shown what conditions must be satisfied before two similar suspensions with the same specific optical density at a given wavelength may be asserted to have the same average floc size, and that it is not possible even to make unambiguous comparisons of relative size from such data alone. A method is developed for obtaining the relative size of the flocs in two suspensions from the specific optical densities, the exponent of the dependence of optical density on wavelength, and single independent estimate of the average size of the dispersed particles in one of the suspensions, obtained by electron microscopy. It is shown that this leads to reasonable values of the average floc radius in suspensions of colloidal carbon in nonaqueous solvents, and for the relative change of floc radius with time due to flocculation of the suspension.

The effect of calcium ions on carbon suspensions

AbstractA high degree of dispersion of carbon black in water is obtained only in the presence of adsorbing long‐chain, amphipathic molecules. Calcium ions flocculate these dispersions, but agglomeration can be prevented if anionic detergents are adsorbed on the carbon. Fine dispersions of carbon coated with a fatty acid or alcohol were maintained in the presence of calcium ions with detergents which coadsorb with the acid or alcohol monolayer. The significance of these results in regard to detergency theory is discussed.

Electrolysis of Manganese into a Metal Cathode from Suspensions of Manganese Oxide and Carbon in Molten Manganous Chloride

We investigated the thermal behavior of dislocation loops formed in a CH3O-multielement-molecular-ion-implanted epitaxial silicon (Si) wafer by real-time cross-sectional tunneling electron microscopy observation with in situ heating. We found that the CH3O-ion-implantation-induced faulted Frank dislocation loops (FDLs) shrink at a low rate at the beginning of heat treatment (1st stage), and then the shrinkage rate rapidly increased (2nd stage), resulting in the dissolution of the defects. The activation energies for the shrinkage of FDLs in the 1st and 2nd stages were found to be 2.94±0.31 and 4.95±0.25 eV, respectively. The shrinkage behavior in the 1st stage is the desorption of C and O atoms that segregated along the edge of an FDL because of the interaction between the CH3O-ion-implantation-induced FDL and the segregated impurities. On the other hand, the 2nd stage corresponds to the desorption of Si atoms from FDLs and its migration. Our experimental results suggest that thermal stability of the dislocation loop is determined by the kind of segregated impurities around the dislocation loop.

The consistency of plastic suspensions of the Bingham type

Abstract )The consistency of a plastic suspension of the Bingham type was characterized by deriving φ‐τ diagrams from the D‐τ diagrams. ) In the case of the plastic suspensions of carbon in mineral oil it is deduced from the φ‐τ relation that the temperature coefficient of the consistency is determined almost entirely by the medium of suspension. ) Attention is called to the large errors caused by the turbulence occurring during measurements at high shearing stresses. ) In order to describe the curved part of a D‐τ diagram more exactly by means of constants, the concept of liquidation tendency is introduced. This liquidation tendency can be read off directly from a φ‐τ diagram.

THE USE OF NUMBERS OF INFECTIONS FOR COMPARING THE CONCENTRATION OF PLANT VIRUS SUSPENSIONS: THE EFFECT OF CARBON ON THE PRODUCTION OF LESIONS BY VIRUSES OF THE TOBACCO MOSAIC GROUP

SUMMARY Tests were made of the spreading power of suspensions of plant juice, finely divided carbon, a commercial spreader, and water on leaves of Nicotiana glutinosa and paraffin wax surfaces. The contact angle of the suspensions of the plant juice and the “spreader” was lower than that of water and suspensions of carbon. When rubbed over the surface the plant juice and “spreader” gave good contact compared with the water, and the particles of carbon adhered to the surface carrying with them a film of water. The effect of carbon and plant juice in raising the number of lesions when present in the inoculum may be explained by the better contact of the inoculum with the leaf surface. Carbon in the form of lamp‐black caused an equal rise in number of lesions with purified suspensions of three viruses. The same virus sample at a number of dilutions showed approximately equal rises in number of lesions in the presence of a uniform amount of lamp‐black. When the lamp‐black was diluted in the same ratio as the virus, the effect diminished. The extent of the rise given by carbon was shown to be largely a function of the leaf tissues, probably of the nature of the leaf surface. Differences were observed between plants and between leaves of the same plant.

LYMPHATIC PATHWAYS FROM THE NOSE: RESEARCH REPORT

In a series of papers beginning in 1919 Mullin 1 has repeatedly called attention to the relation between drainage from the paranasal sinuses and certain types of pulmonary infection. He pointed out that particles of india ink or bacteria introduced into the sinuses of cats and rabbits, the sinus membranes being injured to facilitate absorption, are taken up by the lymphatics and find their way to the bronchial and mediastinal lymph nodes. Mullin and Ryder 2 reported that the inhalation of suspensions of carbon or of tubercle bacilli by rabbits results in pigmentations or tuberculous lesions similar to those of human tuberculosis, including involvement of bronchial lymph nodes. Various clinical observers have emphasized one or the other of the possible routes of entry of infectious material to the lungs and the related lymph nodes in relation to bronchitis, bronchiectasis and other pulmonary disturbances. Quinn and Meyer, 3 Clerf

THE PHAGOCYTOSIS OF SOLID PARTICLES

1. The rates of ingestion of quartz and carbon particles by leucocytes, when both are in suspension in serum, was compared with the availability of the two particles as predicted from the calculated chances of collision with the leucocytes, and it was shown that carbon is ingested about 4 times as readily as quartz. 2. The greater ease of ingestion of carbon was verified by a new method of measuring phagocytosis, described as the film method in which the cells ingest particles as they creep about on a slide. 3. The relative rates of ingestion of carbon and quartz depend upon the condition of the cells, the difference increasing as the phagocytic activity of the cells decreases. 4. Sponge cells also ingest carbon about 3 times as readily as quartz. 5. The hypothesis is suggested that the cause of the more rapid ingestion of carbon may be identical with the cause of the greater instability of the carbon suspensions. 6. An inorganic analogy to this selective phagocytic action is offered. 7. The application to opsonins and agglutinins is discussed.

THE PHAGOCYTOSIS OF SOLID PARTICLES

1. By measurements of the diameter and velocity of leucocytes and of the particles in two carbon suspensions, the relative rates of ingestion of the two suspensions by the leucocytes are predicted and the predictions verified experimentally. 2. The results indicate that 4.7micro particles of carbon are ingested as readily as 3.2micro particles. The more rapid apparent rate of ingestion of the 4.7micro particles is due to their greater availability rather than the greater capability of the leucocytes. 3. There is almost no phagocytosis of carbon in absence of serum or in heated serum. 4. The clumping of unwashed leucocytes is accllerated by serum and by the ingestion of carbon. 5. The available evidence indicates that the phagocytosis of bacteria does not follow the law for a monomolecular reaction, possibly because of the toxic effect upon the leucocytes of bacterial extracts.