Samuel S Morrison

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Gramicidin A (gA), with four Trp residues per monomer, has an increased conductance compared to its Phe replacement analogs. When the dipole moment of the Trp13 side chain is increased by fluorination at indole position 5 (FgA), the conductance is expected to increase further. gA and FgA conductances to Na+, K+, and H+ were measured in planar(More)
Silicone gels derived from commercially obtained implants induce plasmacytomas in 60-70% of highly susceptible BALB/cAn.DBA/2-Idh1-Pep3 congenic mice. In contrast, dimethylpolysiloxane (DMPS) silicone oils with viscosities of 5, 1000 and 12,500 cs fail to elicit these tumors. 1000 cs vinylmethylpolysiloxane is also inactive. Silicone gels, in contrast to(More)
BACKGROUND Plasmacytomas can be induced in high frequency in susceptible strains of mice by the intraperitoneal introduction of plastics or paraffin oils, including the chemically defined oil pristane (2,6,10,14-tetramethylpentadecane). These materials persist in the peritoneal cavity, where they induce chronic inflammation during the long periods before(More)
Aeolian and pluvial processes represent important mechanisms for the movement of actinides and fission products at the Earth's surface. Soil samples taken in the early 1970's near a Department of Energy radioactive waste disposal site (the Subsurface Disposal Area, SDA, located in southeastern Idaho) provide a case study for studying the mechanisms and(More)
Silicone gels injected intraperitoneally into strains of mice related to BALB/c develop plasmacytomas in approximately the same numbers and with similar phenotypes as previously obtained with pristane. Silicone gels produce few side effects and are well tolerated for long periods. Silicone gels contain several components that are potentially biologically(More)
We postulated that water condensate in endotracheal tubes (ETTs) transports bacteria in the ETTs into the lungs during mechanical ventilation. Thirty-two ETTs obtained from freshly extubated patients were studied under wet and dry conditions using a physiologic lung model. All bacteria expelled from the ETTs were collected on culture plates positioned(More)
Although other investigators have attempted to demonstrate that histamine has the power of producing acute ulcers when injected locally into the stomach wall, our experiments show clearly that this is a very inconstant finding for, of six instances, we were only able to obtain a small healed mucosal ulcer in one. Even when dilute acid (0.3 per cent(More)
Tantalum (Ta), hafnium (Hf), and tungsten (W) analyses from complex matrices require high purification of these analytes from each other and major/trace matrix constituents, however, current state-of-the-art Ta/Hf/W separations rely on traditional anion exchange approaches that show relatively similar distribution coefficient (Kd) values for each element.(More)
Solid sampling and analysis methods, such as laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), are challenged by matrix effects and calibration difficulties. Matrix-matched standards for external calibration are seldom available and it is difficult to distribute spikes evenly into a solid matrix as internal standards. While isotopic(More)
Environmental 237Np analyses are challenged by low 237Np concentrations and lack of an available yield tracer; we report a rapid, inexpensive 237Np analytical approach employing the short lived 239Np (t1/2 = 2.3 days) as a chemical yield tracer followed by 237Np quantification using inductively coupled plasma-mass spectrometry. 239Np tracer is obtained via(More)