An Analytical Model of the Counter-Current Heat Exchange Phenomena

An analytical model for the counter-current heat exchange mechanism in animals has been formulated and a solution has been obtained. The nondimensional parameters that govern the mechanism have been determined in terms of the properties of the animal. The normalized temperatures are functions of normalized distance and, in general, three nondimensional heat transfer conductances. Graphical results are presented for two representative physiological systems. These results allow a delineation of those situations in which counter-current heat transfer is important, and also a quantitative prediction of the heat transfer and temperature distributions. The theory is compared to the available experimental results.     

Endogenous gibberellins of a radiation induced single gene dwarf mutant of bean

The distribution of endogenous gibberellins in Dwarf-1, a single gene dwarf mutant of Mexico 80-R red beans, was studied. Parallel extraction and fractionation of seeds of this mutant and those of a normal homozygous line followed by thin layer chromatography and bioassays using Rumex obtusifolius, wheat seed endosperm and dwarf bean plants revealed that a stem elongation control factor was contained in the non-acidic fraction from normal, but not from Dwarf-1, seeds. It was concluded that the single gene mutation causes a block either in gibberellin precursor formation or in production of a non-acidic fraction gibberellin-like substance.     

Microbiological Contamination of Hospital Air: I. Quantitative Studies

The levels of airborne contamination in various areas of two hospitals were determined during a 15-month sampling period, using Casella and Andersen volumetric samplers. Based on nearly 5,000 samples, the mean count per ft³ ranged from 4.5 in obstetric-gynecology delivery rooms to 72.4 in waste-handling areas. The mean count for the entire hospital environment was on the order of 20 contaminants per ft³; 48% were associated with particles >5 μ diam, 30% with particles between 2 and 6 μ diam, and 22% with particles <2 μ diam. The airborne contamination was influenced by traffic, activity, ventilation considerations, and gross surface contamination, but not markedly by seasonal changes. When suitable control measures were implemented, the level of contamination could be diminished and kept low.     

Microbiological Contamination of Hospital Air: II. Qualitative Studies

Over 10,000 airborne microorganisms, isolated from various areas of two hospitals, were characterized according to colonial and microscopic morphology and certain physiological reactions, including penicillin resistance and hemolysis. On the basis of all isolates examined during a 15-month period, 42.6% were gram-positive cocci, 19.2% were gram-positive rods, 14.0% were gram-negative rods, 17.1% were molds, 2.2% were actinomycetes, 1.2% were yeasts, and the remainder were assorted diphtheroids and coccobacillary types. The distribution of types varied according to hospital area, locations within a given area, and level of gross airborne contamination, but did not vary significantly with season of the year. There appeared to be some relationship between contaminant particle size and type of organism associated with the particle. Distribution of penicillin-resistant types differed markedly in different hospital areas, with proportions ranging from 21.4% in surgery areas to 4.3% in incinerator rooms. Of all gram-positive cocci isolated, 34.9% were hemolytic, and 16.4% were penicillin-resistant.     

In Vitro Studies on the Antiviral Activity of 1,3-Bis(2-Chloroethyl)-1-Nitrosourea

Chemotherapy experiments carried out in vitro demonstrated that 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) was active against lymphocytic choriomeningitis virus and had an equivocal antiviral effect on Semliki Forest, herpes simplex, and vaccinia viruses. No antiviral effect was observed with BCNU against western equine encephalomyelitis, polio, and parainfluenza (HA-1) viruses. Activity of the drug was determined by inhibition of viral-induced cytopathogenic effect in KB or chick embryo cells and by reduction of virus titer in cell culture supernatant fluid. Maximal activity against the viruses was observed when drug and virus were incubated together for 30 min prior to addition to cells; essentially no activity could be demonstrated if BCNU and virus were added to cells with no prior incubation.