Clean Side Research Articles

A possible role for Syrian hamster, Mesocricetus auratus, vaginal secretion in inter-female competition

The ability of the vaginal secretions of hamsters to facilitate spacing among conspecific females was examined in three experiments. In the first study, vaginal substances were applied to one half of a testing arena. Naive females placed into this apparatus spent significantly more time on the clean side and tended to deposit vaginal secretions in this area more often. In the second experiment, vaginal odours were again applied to the testing arena. The donor of the secretion and a second female were then introduced into the arena and allowed to interact. The females whose odours had been applied in the arena were significantly more aggressive. The third study evaluated the effectiveness of vaginal odours to reverse a recently established dominance relationship between female pairs. In eight of 12 pairs, a reversal was observed if the previously subordinate hamster's odours were present in the testing enclosure during the second dominance determination. The results of these studies indicate that vaginal marks could serve to space females in the native habitat. These substances are capable of inducing avoidance of a scented area and influencing the outcome of dominance contests.

Compositional non-uniformities in selective area growth of GaInAs on InP grown by OMVPE

Selective area epitaxial growth of Ga0.47In0.53As on InP substrates patterned with silicon nitride was done by low pressure organometallic vapor phase epitaxy. Good surface morphology and clean side walls of the epitaxial layers were obtained in most of the areas of selective GalnAs growth. However, both GaAs incorporation and InAs incorporation increased near the edges of the selective growth areas due to the extra flux of Gacontaining and In-containing species migrating on the surface of silicon nitride. The increase in InAs incorporation was found at a higher rate when the adjacent silicon nitride area was large, hence, cross-hatching appeared near the edges. A characteristic length of adjacent silicon nitride seemed to be connected with the enhanced InAs incorporation, which was about 40μm at 600°. The non-uniformities in composition appeared in all wafers grown in the temperature range between 570 and 650°.

Fabric cleaning in pulse-jet filters

In pulse-jet filters, bag cleaning is accomplished by a compressed air pulse being injected into the clean side of a filter bag. This causes an abrupt increase in pressure within it, leading to a flow reversal as well as to acceleration of the filter cloth. Investigations with a 2.5 m long filter bag have shown that it is not the forces arising from the fabric acceleration, but those arising from the reverse air flow which play the major role in bag cleaning, and that the dust-cake release is related to the peak pressure built up inside the bag. In order to achieve complete dust dislodgement, a critical overpressure is necessary at every location along the length of a bag for a certain period of time. This overpressure depends on the dust-cake-fabric interaction. Experiments with flat-geometry fabric samples have shown that the critical overpressure can be found from a laboratory-scale experiment.

Failure of the sterile air-flow component of a protected environment detected by demonstration of Chaetomium species colonization of four consecutive immunosuppressed occupants.

Four bone marrow transplant recipients consecutively occupying the same room on our Oncology-Hematology Special Care Unit (OHSCU) became colonized with Chaetomium species between January and April, 1987. These patients, aged 27 to 43 years, were immunocompromised as a result of intensive chemotherapy, and were consequently at increased risk for development of invasive fungal infection. At the time of Chaetomium colonization, all patients were febrile, two had transient new infiltrates on chest x-ray, and three were receiving amphotericin B therapy. Subsequent environmental cultures revealed Chaetomium contamination of the OHSCU air-handling system, including the HEPA (high-efficiency particulate air) filters in seven of the nine rooms comprising the unit. Because fungal colonization of HEPA filters used to create a "protective environment" for immunocompromised patients can occur and can serve as a source for patient infections, guidelines concerning proper surveillance of these HEPA filters should be established. We suggest that before a new patient enters a "protected" room, the clean side of the HEPA filter should be cultured. If fungi are recovered from that culture, we would recommend changing the filter.

Failure of the Sterile Air-Flow Component of a Protected Environment Detected by Demonstration of Chaetomium Species Colonization of Four Consecutive Immunosuppressed Occupants

AbstractFour bone marrow transplant recipients consecutively occupying the same room on our Oncology-Hematology Special Care Unit (OHSCU) became colonized with Chaetomium species between January and April, 1987. These patients, aged 27 to 43 years, were immunocompromised as a result of intensive chemotherapy, and were consequently at increased risk for development of invasive fungal infection. At the time of Chaetomium colonization, all patients were febrile, two had transient new infiltrates on chest x-ray, and three were receiving amphotericin B therapy. Subsequent environmental cultures revealed Chaetomium contamination of the OHSCU air-handling system, including the HEPA (high-efficiency particulate air) filters in seven of the nine rooms comprising the unit. Because fungal colonization of HEPA filters used to create a “protective environment” for immunocompromised patients can occur and can serve as a source for patient infections, guidelines concerning proper surveillance of these HEPA filters should be established. We suggest that before a new patient enters a “protected” room, the clean side of the HEPA filter should be cultured. If fungi are recovered from that culture, we would recommend changing the filter.

4464184 Apparatus and method for the control of the precoating of an effluent filtration baghouse utilizing clean side pressure measurement: Thomas J Cera, Charles A Price assigned to United States Steel Corporation

4464184 Apparatus and method for the control of the precoating of an effluent filtration baghouse utilizing clean side pressure measurement: Thomas J Cera, Charles A Price assigned to United States Steel Corporation

Auto- and allo-grooming in pine voles ( Microtus pinetorum) and meadow voles ( Microtus pennsylvanicus)

Grooming was observed in mixed-sex pairs of voles after one vole had been unilaterally soiled with a carboxymethylcellulose (CMC) gel. In Experiment 1, soiled pine voles spent more time grooming than did clean voles, and groomed the soiled side of their bodies more than the clean side. Soiled voles of both species head-groomed more than did clean voles. Addition of tastants to CMC gel did not alter grooming durations in either species, and there were no sex differences. In Experiment 2, both vole species (taken together) auto-groomed more than they allo-groomed, although clean voles groomed their soiled partners more than themselves. These studies suggest that soiled fur is a powerful stimulus for auto- and allo-grooming.

Grooming in the Norway rat: Displacement activity or “boundary-shift”?

The self-grooming behavior of 11 domestic male Norway rats (Rattus norvegicus) was observed in silence (control condition) and when recorded rat screams were introduced. Upon exposure to the auditory stimulus, significant increases over control levels were observed in the total grooming time, number of grooming bouts, percentage of the total grooming time attributable to face washing, and the number of sample periods in which grooming occurred. Nonsignificant increases were evident for the average bout duration and the absolute time spent face washing. Twenty subjects were then soiled unilaterally with 30 ml of a 2% aqueous agar solution; 10 of these were observed in silence (undisturbed) and 10 in the presence of rat screams (disturbed). Undisturbed subjects groomed the soiled body side significantly more than the intact (clean) side. Disturbed subjects, however, showed no such clear preference in laterality. It is concluded that exposure to auditory stimuli resulted in alterations of grooming behavior. Furthermore, while local pelage factors served to orient grooming in the undisturbed subjects, such factors played a lesser role among disturbed subjects. Although these results are superficially suggestive of a displacement activity, they are more adequately considered within the framework of a more dynamic view of motivational control.

Cooling with geothermal heat

Fisher & Paykel Engineerign contracted to design and build a geothermally powered air conditioning and domestic hot water system for the new Tourist Hotel in Rotorua, New Zealand, involving about 2,000,000 BTU/h supplied by geothermal hot water. A buffer heat exchanger between the 300°F bore and 250°F clean hot water was used to serve absorption refrigeration as well as heating systems and domestic hot water calorifiers on the clean water side. Some comments are made on aspects of the design, control and general installation.

Adsorption of Thorium on Tantalum

It is known that thorium adsorbed on the surface of tungsten or molybdenum results in a decrease in the work function and also a decrease in the value of $A$, the emission constant. The behavior of thorium on tantalum was investigated, and similar effects were noted. Thorium was evaporated from thoriated tungsten onto a well-outgassed tantalum ribbon, and the thermionic emission at 1390\ifmmode^\circ\else\textdegree\fi{}K was studied as a function of the time of evaporation. The work function of the ribbon changed from 4.07 volts to 2.52 volts, while $A$ decreased by a factor of thirty. The ribbon was then held at 1550\ifmmode^\circ\else\textdegree\fi{}K, and the emission from the two sides was studied separately. The emission from the activated side decreased, while that of the clean side increased until both reached the same final level after about twenty hours. This indicates that the adsorbed thorium had migrated around the edges of the ribbon and distributed itself uniformly over the emitting surface.