Sulfur coating of urea treated with attapulgite clay

A commercial attapulgite-type gelling clay was added as a conditioning-hardening agent to urea which was then tested as a substrate for sulfur coating. The coating tests were made in bench-scale batch equipment. The total coating weights and the 7-day dissolution rates of the sulfur-coated products were determined and compared with those from similar tests of previously made sulfur-coated urea products containing calcium lignosulfonate or formaldehyde. Compared with urea substrates containing formaldehyde, the urea containing attapulgite clay required about one-third less sulfur coating to attain the same 7-day dissolution rate. The urea containing attapulgite clay and the urea containing calcium lignosulfonate were about equally effective as substrates for sulfur coating.     

Hazard assessment techniques used in the chemical industry and their possible uses elsewhere

The traditional methods used for the identification and assessment of hazards in the chemical industry are based on experience, but increased economic and environmental restrictions on its operations have required the development of other methods to ensure that an acceptable level of safety is maintained. The present paper briefly reviews the traditional methods, describes in mire detail the basis of the newer methods, namely hazard and operability studies and hazard analysis, and considers how they might be more widely used in assessing fire hazards.     

Single myosin molecule mechanics: piconewton forces and nanometre steps

A new in vitro assay using a feedback enhanced laser trap system allows direct measurement of force and displacement that results from the interaction of a single myosin molecule with a single suspended actin filament. Discrete stepwise movements averaging 11 nm were seen under conditions of low load, and single force transients averaging 3-4 pN were measured under isometric conditions. The magnitudes of the single forces and displacements are consistent with predictions of the conventional swinging-crossbridge model of muscle contraction.     

APA accreditation: A status report.

Outlines the evolution of the procedures and mechanisms of American Psychological Association (APA) accreditation (ACR) between 1966 and 1971. Under the present system, APA accredits professional programs as units rather than singling out individual specialities, programs put on probation are so identified in lists of approved programs, a provisional ACR category has been added, and greater emphasis has been placed on the advisory and consulting functions of the ACR process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Alveolar rhabdomyosarcoma involving the heart. An echocardiographic, angiographic and pathologic study

A 12-year-old girl, who had had an above-knee amputation of the left leg for a soft tissue sarcoma six years prior to this admission, presented with syncope, angina, and signs of aortic stenosis. Echocardiography demonstrated a mass arising from the interventricular septum with obstruction of the left ventricular outflow tract and aortic valve. Cardiac catheterization and angiography confirmed these findings. At operation, a tumor was found involving the interventricular septum. Histologically, it was an alveolar rhabdomyosarcoma, and it appeared similar to the previous tumor. The patient was treated by partial surgical resection, cytotoxic drugs and localized radiation therapy and has been followed by serial echocardiography.     

Primary retinal degeneration: evidence of normal phagocytosis in the retinal pigment epithelium

In rats with primary retinal degeneration, lens extraction combined with total retinal detachment provided a model for injection of a tracer of colloidal carbon into the subretinal space. Electron microscopy and acid phosphatase cytochemistry were subsequently used to analyze the ingestion of tracer by the retinal pigment epithelium. It was found that the attachment, ingestion, and digestion phases of the phagocytic process were apparently preserved. From this evidence it is suggested that there is no lack of phagocytic power in the retinal pigment epithelium of affected rat strains.     

A p-channel BICFET in the InGaAs/InAlAs material system

The bipolar inversion-channel field-effect transistor (BICFET) relies on a field-effect mechanism to induce and modulate an inversion layer placed at the heterojunction interface. The device was fabricated using molecular beam epitaxy. A current gain of ~15 has been achieved at a current density J of ~8×10³ A/cm² at 300 K. At 77 K, the gain rises to 40 with J=2×10⁴ A/cm². This gain, which follows theoretical predictions, continuously increases with collector current and is limited only by the amount of heat generated in a large-area device. Because of its potential for ballistic transport in the collector, the InGaAs/InAlAs BICFET should be very attractive for high-speed applications     

A survey of information authentication

The general principles that underlie all authentication schemes are reviewed and illustrated using the examples of an early telegraphy cable code, a US military authentication protocol, and authentication of electronic funds transfers in the US Federal Reserve System. Authentication threats from inside the system (i.e. untrustworthy sender or receiver) are described. The classification of authentication schemes as computationally secure, provably secure, or unconditionally secure is explained, and theoretical results are presented showing that a large number of encoding rules must be available in any unconditionally secure authentication code. Current authentication practices are examined     

Hemodynamics in sleep-induced apnea. Studies during wakefulness and sleep

Twelve patients with predominantly obstructive type sleep apnea underwent cardiac catheterization, hemodynamic monitoring, and arterial blood gas analysis during wakefulness and sleep. Abnormalities during wakefulness included systemic hypertension in four of 12, exercise-induced mild pulmonary hypertension in five of 12, and alveolar hypoventilation in one. During sleep nine patients had cyclic elevations of arterial pressure with each apneic episode, exceeding 200 mm Hg systolic in three of 12. Pulmonary artery pressures increased in 10 of 12, exceeding 60 mm Hg systolic in five. Marked degrees of hypoxemia (arterial P02, less than 50 mm Hg in eight of 12) and moderate hypercapnia with respiratory acidosis were associated with these hemodynamic changes. Cyclic upper airway obstruction during sleep may result in hypercapnia, acidosis, and pronounced hypoxemia, which can lead to hemodynamic abnormalities during sleep. Sustained pulmonary hypertension and possibly systemic hypertension may follow. Tracheostomy is an effective therapy and is recommended to symptomatic patients who have predominantly obstructive apnea but no relievable anatomic cause of upper airway obstruction.