Mechanism of expansion associated with ettringite formation

Ettringite formation in portland cement concretes can be responsible for both deleterious and beneficial phenomena. Several hypotheses on the mechanism of expansion associated with ettringite formation are reviewed, and a new hypothesis is proposed. Experimental evidence is presented in support of the new hypothesis. It is shown that in the presence of lime the nature of ettringite formed is colloidal, and not long lath-like crystals. It is proposed that colloidal ettringite is able to attract a large number of water molecules which cause interparticle repulsion, thus causing an overall expansion of the system.     

Prediction of transport properties of composites from equations of elasticity

The mathematically-analogous equations of elasticity were used to predict the transport properties of anisotropic composite films. Composite films of controlled structural and physical characteristics were prepared by embedding impermeable glass ribbons in a cellulose acetate matrix. Simple but approximately-precise equations of composite moduli developed by Halpin and Tsai were used to predict the composite permeability in terms of the permeabilities of the constituent phases and a structure factor which is a measure of the filler reinforcement and signifies the resistance of the filler phase to the diffusive flow in the composite medium. The discrepancy between the theoretical predictions and experimental composite permeabilities has been explained in terms of diffusive flux lines not staying in a single direction. In the case of glass ribbons the diffusive1 flow lines tend to bend away from the ribbons (regions of lower permeabilities). The extent of influence of the filler phase to impede the overall composite permeation is a function of the geometry, orientation and volume fraction of the filler.     

Studies on α-pinene–furfural-based cation exchange resins. I. Preparation of polymeric compositions and resins

A crosslinked polymer based on α-pinene and furfural suitable for processing into ion exchangers was prepared. The polymer has been processed chemically into different types of cation exchange resins. The role of various parameters such as catalyst concentration, proportion of crosslinking agent, etc., for preparing the polymer is systematically studied and presented. Similarly, the conditions for preparing the various cation exchange resins (sulfonic, phosphonic, and hydroxy phosphonic acid type from the polymer) are also described. A probable/possible composition for the repeating unit in the basic polymer is proposed and supported by experimental evidences.     

Renal failure after open heart surgery

One hundred fifty of 490 patients undergoing open heart surgery had renal failure attributable to cardiopulmonary bypass. In 69, serum creatinine concentrations did not exceed 2 mg/dl and returned to normal by the fourth postoperative day. In 60 patients, serum creatinine attained levels between 2 and 5 mg/dl, oliguria did not develop, and recovery of renal function occurred within 4 to 37 days. Serum creatinine increased to levels exceeding 5 mg/dl in 21 patients, 11 of whom were oliguric. Despite dialysis, 14 of these patients died from cardiac causes or sepsis. Prolonged cardiopulmonary bypass time, hypotension, oliguria, low output syndrome, and hemoglobinemia during open heart surgery correlated with the development of renal failure postoperatively. Although severe renal failure was an uncommon complication after open heart surgery, its occurrence carried a grave prognosis.     

Lanolin with reduced sensitizing potential. A preliminary note

The allergens of lanolin appear to lie in the content of natural free fatty alcohols rather than in the total alcohols as hitherto supposed. The detectable incidence of allergy is increased by the simultaneous presence of detergent. Amongst selected lanolin-sensitive skin patients, removal of both free fatty alcohols and detergent from lanolin reduces the incidence of detectable hypersensitivity by 96%. Methods are described for determining free fatty alcohols and detergent in lanolin, and for removing them.