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Experiments are described in which structured discharges, including stationary and moving striations, were observed in 4 MHz rf plasmas generated using two solenoidal coil configurations. The structured plasmas which formed in the vicinity of the solenoidal coils were not quenched when elaborate precautions were taken to shield the capacitive electric fields. Measurements of the rf power input to the plasma and the resistance reflected by the plasma into the drive circuit showed no discontinuous change during the formation or disappearance of the structured discharges surrounding the solenoidal coils. Observations of striated rf discharges reported by other investigators are reviewed. Arguments are given to support the conclusion that the striation-like structures observed in rf plasmas and the moving striations observed in dc plasmas are part of the same general family.Much of the work described in this paper was supported by the Air Force Office of Scientific Research. One of us (RCW) received partial support from Contract DAAA 13-68-C-0033 and Grant NSF GK-24150. 相似文献
105.
Melvin C. Thornton 《Discrete Mathematics》1982,41(3):303-307
This note gives a counterexample to a published characterization of regular elements in sandwich semigroups of binary relations. The method of that paper is used to characterize those elements having a right identity. A characterization of regular elements is obtained following the approach of Schein. 相似文献
106.
C.-A. Wiedner R. Haupt W. Saathoff J. Haas R. Gyufko K.R. Cordell S.T. Thornton R.A. Cecil R.L. Parks 《Nuclear Physics A》1983,411(1):151-160
Accurate mass measurements for the nuclides 79As, 81As, and 80Ge have been measured. Good agreement has been found for 79As and 81As with the Garvey-Kelson transverse mass relation and with several mass model predictions. The agreement for 80Ge is not as satisfactory and presents a challenge for understanding mass values far off the line of stability. 相似文献
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Takulapalli BR Laws GM Liddell PA Andréasson J Erno Z Gust D Thornton TJ 《Journal of the American Chemical Society》2008,130(7):2226-2233
A close-packed monolayer of zinc 5,10,15,20-tetrakis(3-carboxyphenyl)porphyrin has been prepared and deposited on the thin native oxide covering the surface of an SOI-MOSFET (silicon-on-insulator metal-oxide-semiconductor field effect transistor) using Langmuir-Blodgett techniques. When the device is exposed to amine vapors in a nitrogen atmosphere, the amine coordinates to the zinc atom. The resulting change in electron distribution within the porphyrin leads to a large change in the drain current of the transistor, biased via a back gate. This change is sensitive to both the amount of amine present and the base strength of the amine. Only very small changes in drain current were observed with a monolayer of free base porphyrin or palmitic acid. After exposure to high pyridine concentrations, the device response saturates, but partially recovers after overnight exposure to flowing nitrogen gas. Interestingly, the device response is instantaneously reset by exposure to visible light, suggesting that photode-ligation occurs. An electrical model for the hybrid device that describes its response to ligand binding in terms of a change in the work function of the porphyrin monolayer has been developed. A transistor response to a few hundred attomoles of bound pyridine can be readily detected. This extreme sensitivity, coupled with the ability to reset the device using light, suggests that such systems might be useful as sensors. 相似文献
109.
Farago ME Kavanagh P Blanks R Kelly J Kazantzis G Thornton I Simpson PR Cook JM Parry S Hall GM 《Analytical and bioanalytical chemistry》1996,354(5-6):660-663
Concentrations of Pt, Pd, Rh and Au in soils and road dusts taken from areas of high and low traffic flows in the London Borough of Richmond and from a section of the Kingston bypass (A3) at New Malden, Surrey, have been measured. High concentrations of platinum are associated with high traffic densities. Samples taken from streets of lower traffic flows were found to contain the lower concentrations of the ranges. These values correlated well with the levels of lead which were also high at roundabouts. If the preliminary results obtained in this study apply more generally throughout the UK, then the potential for exposure to enhanced levels of Pt would appear to be higher for road users and for those living in urban environments or along major highways. 相似文献
110.
Xiaoming Liu Colin A. Kilner Mark Thornton‐Pett Malcolm A. Halcrow 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(9):1142-1143
The title compound, C17H13N3, is a versatile precursor for polymeric terpyridine derivatives and their metal complexes. The molecule has transoid and near‐coplanar pyridine rings. However, the vinyl group is forced out of the plane of the terpyridyl moiety by a close H?H contact. 相似文献