Measurements of wall heat (mass) transfer for flow through blockages with round and square holes in a wide rectangular channel

Naphthalene sublimation experiments were conducted to study heat (mass) transfer enhancement by blockages with staggered round and square holes for turbulent air flows through a wide rectangular channel. The blockages and the channel had the same cross-section. The results showed that the blockages enhanced the average heat (mass) transfer on the channel walls by 4.7-6.3 times that for fully developed turbulent flow through a smooth channel. The blockages with round holes enhanced more heat (mass) transfer on the channel walls but caused larger pressure drops than the blockages with square holes, which had a 27% larger flow cross-sectional area.     

Diffusion through ordered force fields in nanopores represented by Smoluchowski equation

The classical Einstein or Fick diffusion equation was developed in random force fields. When the equation is applied to gas transport through coal, significant discrepancies are observed between experimental and simulation results. The explanation may be that the random force field assumption is violated. In this article, we analyze molecular transport driven by both random and ordered (directional) forces in nanopores. When applied to CO₂ transport through cone‐shaped carbon nano‐tubes (CNTs) and Li⁺ doped graphite pores, computational results show that directional force fields may significantly affect porous media flow. Directional forces may be generated by potential gradients arising from a range of non‐uniform characteristics, such as variations in the pore‐sizes and in local surface compositions. On the basis of the simulation and experimental results, the Smoluchowski and Fokker‐Planck equations, which account for the directional force fields, are recommended for diffusion through ordered force fields in nanopores. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Correlation of cerebral blood flow with outcome in head injured patients

In order to determine the relationship of cerebral blood flow (CBF) to the clinical outcome of head injury, serial determinations of CBF were performed by the intravenous Xenon technique in 24 patients. The patients were of mixed injury severity and were classified into four groups depending on the neurological exam at the time of each CBF study. All eight patients who were lethargic on admission demonstrated increases in their minimally depressed CBF as they improved to normal status. Eleven patients in deep stupor or coma ultimately recovered. Ten of these patients initially had moderate to profound decreases in CBF which improved as recovery occurred. The single exception was an adolescent whose initial CBF was high but became normal at recovery. Five comatose patients died. In four of these, already depressed CBF fell even lower, while one adolescent with initially increased CBF developed very low CBF preterminally. The data presented in this report demonstrated a good correlation between CBF and clinical outcome. In every one of the adult survivors, depressed CBF increased as the patient recovered to normal status. All adults who died showed a deterioration of CBF as the neurological status worsened. The only exceptions were two adolescents who initially showed high CBF values. In the adolescent who died, CBF dropped to low levels while in the survivor a normal CBF was achieved. Thus in adults a traumatic brain injury was associated with depressed CBF which increased with recovery or decreased further with deterioration while the reaction to injury was quite different in the younger brain.     

Intraventricular chemotherapy in neonatal meningitis

All of 16 infants with neonatal meningitis treated during a 30-month period were found to have accompanying ventriculitis at the time of the initial ventricular puncture. Fifteen of these infants were caused by gramm-negative organisms. All infants received antibiotics systemically and intraventricularly via an implanted ventriculostomy reservoir or by direct ventricular injection. Antibiotic concentrations within the ventricular fluid were monitored during chemotherapy; the complications encountered during treatment are discussed. Fifteen infants survived the infection; of these, seven infants were normal at follow-up examinations. In our experience intraventricular chemotherapy as an adjunct to systemic administration of antibiotics has greatly reduced the mortality rate in neonatal meningitis.     

Polyurethane foam (Bentley) micropore blood transfusion filter: filtration characteristics

Stored human blood of varying age was passed through polyurethane foam (Bentley) micropore blood transfusion filters. Passage through these filters resulted in decreased screen filtration pressure (SFP) of the blood and increased filter weights. Numerous microaggregates were removed and SFP returned to normal after filtration. Occlusion of the filter occurred after passage of only 2 units of whole blood. On the basis of this research, we conclude that polyurethane foam (Bentley) micropore blood transfusion filters are effective in removal of microaggregates from stored human blood. Because the filtering capacity is not great, it is recommended that when these filters are used during transfusion a new filter be used for each unit of blood administered.     

Relationship between mouth occlusion pressure and electrical activity of the diaphragm: effects of flow-resistive loading

We determined the relationship between mouth occlusion pressure and diaphragmatic electromyography during CO2 rebreathing with and without inspiratory flow resistance. Diaphragmatic electromyography was measured as a moving time average; occlusion pressures were measured 150 msec after onset of an inspiratory effort against a closed airway (P.15). P.15 versus diaphragmatic electromyographic plots during CO2 rebreathing with and without inspiratory flow resistance were linear. In 3 subjects the slope of P.15 versus diaphragmatic electromyography was unchanged with inspiratory flow resistance whereas in 3 others the slope increased, indicating greater inspiratory force for a given degree of diaphragmatic activity. We concluded that under unloaded conditions P.15 is a reliable index of respiratory neural output but may no longer reflect only inspiratory motoneuron drive during mechanical loading.