EXPERIMENTAL AND NUMERICAL INVESTIGATION OF ICE ACCRETION ON AIRFOIL

Open Circuit Icing Research Tunnel was developed to test the ice shape under simulated icing conditions. Standard icing blade technique was used to measure liquid water content (LWC) in the icing tunnel test section. The uniformity of liquid water content was assessed by accreting ices on aluminum cylinder bars. Mean volumetric diameter (MVD) of the spray cloud was determined by soot-coated slide and verified through the limits of impingement. Ice accretion tests were performed on a NACA0012 wing model in typical rime and glaze conditions. Results were compared to ice shapes numerically predicted by Messinger method in the same conditions. It is indicated that good overall agreement is achieved in both icing shape and impingement limit.

In vitro bactericidal and in vivo therapeutic activities of a new rifamycin derivative, KRM-1648, against Mycobacterium tuberculosis.

The in vitro and in vivo activities of a new rifamycin derivative, KRM-1648, against Mycobacterium tuberculosis H37Rv were compared with those of rifampin. Bactericidal activity was evaluated by using a silicone-coated slide culture method. The MBC of KRM-1648 was 0.15 to 0.3 microgram/ml for 24 h of exposure, while that of rifampin was > 160 microgram/ml under the same conditions. Against experimental murine tuberculosis, KRM-1648 exhibited significant therapeutic effects, in terms of prolonged survival times for mice compared with those with rifampin treatment, even at lower doses, such as 1 and 3 mg/kg. At a dose of 3 mg/kg, KRM-1648 was at least as effective as rifampin at 10 mg/kg. The combination of KRM-1648 (3 mg/kg) plus isoniazid (3 mg/kg) plus ethambutol (10 mg/kg) exhibited much more activity than did rifampin (10 mg/kg) plus isoniazid (3 mg/kg) plus ethambutol (10 mg/kg). These findings suggest that KRM-1648 is a promising candidate for the treatment of tuberculosis.

Estimation of seasonal ascospore production of Mycosphaerellapopulorum

A model was developed that estimates ascospore production by Mycosphaerellapopulorum Thompson in response to degree-days. Spore production and release in two field seasons were monitored with an ascospore liberation tunnel and Vaseline-coated slide traps, respectively. Ascospore production in a moist environment and under controlled temperatures was monitored in the laboratory with the liberation tunnel. Ascospores were produced in the laboratory for periods of 192, 98, and 74 days at 9, 16, and 21 °C, respectively, after initial ascospore maturation. Field and laboratory ascospore collection data were linearized with a Gompit transformation. Regression coefficients on the linearized data were greatest when a degree-day base of 0 °C was used. Slopes of the regression lines (k-values) developed from laboratory and field (1984 season) data were not significantly different. The k-values from laboratory data and data collected during the 1985 growing season were significantly different. The difference was attributed to dry weather during the period of ascospore production and release. The laboratory regression model could be used to predict ascospore production during the growing season after initial ascospore maturation if adequate moisture is present and if degree-day accumulation is predicted.

The Role of Endoplasmic Reticulum in the Repair of Amoeba Nuclear Envelopes Damaged Microsurgically

The nuclear envelopes of amoebae were damaged microsurgically, and the fate of the lesions was studied with the electron microscope. Amoebae were placed on the surface of an agar-coated slide. Using a glass probe, the nucleus was pushed from an amoeba, damaged with a chopping motion of the probe, and reinserted into the amoeba. Cells were prepared for electron microscopy at intervals of between 10 min and 4 days after the manipulation. Nuclear envelopes studied between 10 min and 1 h after the injury displayed extensive damage, including numerous holes in the nuclear membranes. Beginning 15 min after the manipulation, pieces of rough endoplasmic reticulum intruded into the holes in the nuclear membranes. These pieces of rough endoplasmic reticulum subsequently appeared to become connected to the nuclear membranes at the margins of the holes. By 1 day following the injury, many cells had died, but the nuclear membranes were intact in those cells that survived. The elaborate fibrous lamina or honeycomb layer characteristic of the amoeba nuclear envelope was resistant to early changes after the manipulation. Patches of disorganization of the fibrous lamina were present 5 h to 1 day after injury, but the altered parts showed evidence of progress toward a return to normal configuration by 4 days after the injury. It is proposed that the rough endoplasmic reticulum participates in the repair of injury to the nuclear membranes. The similarity of this repair process to reconstitution of the nuclear envelope in telophase of mitosis is noted, and the relationship between the nuclear envelope and the rough endoplasmic reticulum is discussed.

THE USE OF SEMI-PERMANENT MOUNTS IN SANITATION COLLABORATIVE WORK1

Due to the failure of technicians to agree on their results, it is very difficult to obtain significant answers to problems of sanitation analysis through collaborative tests. Much of the reason for disagreement is individual differences in ability to count fragments and rodent hairs. The paper describes a technique whereby these differences are smoothed out. Filter papers bearing residues from sanitation tests are embedded in a thin layer of paraffin and read collaboratively. The paraffin is melted while the filter paper is being read, and then solidifies, anchoring all particles in place. In addition to giving more reliable results, the paraffin-coated slide technique has shown its self to be a good training medium.