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J M Kenny

Publications and source records attributed to J M Kenny.

6 recordsLinked to original sources
PubMed2005

Soft-x-ray photoemission spectroscopy and ab initio studies on the adsorption of NO2 molecules on defective multiwalled carbon nanotubes.

The adsorption of NO(2) molecules on defective multiwalled carbon nanotubes has been studied by soft-x-ray photoemission. The valence band and carbon core-level spectra have been acquired before, during, and after NO(2) exposure. The spectra show a reversible decrease of the density of states at the top of the valence band when NO(2) molecules are adsorbed on the (carbon nanotubes) CNTs. No shift of the C 1s spectra has been observed. Theoretical calculations, using density-functional theory, have been performed on the CNT + NO(2) system, considering semiconducting nanotubes with different diameters and introducing a Stone-Wales [Chem. Phys. Lett. 128, 501 (1986)] defect. The calculation confirms the decrease of the density of states at the top of the valence band in the CNT + NO(2) system, while close to the adsorption site new states appear very close to the Fermi level.

Journal Article↗
PubMed2005

Clustering and cooperative dynamics in a reactive system.

We study the dependence of the dynamics on the size of particle clusters that grow by stepwise aggregation in a reactive epoxy-amine mixture. The data reveal the cluster property involved in the glasslike arrest and its quantitative link with the structural relaxation time. We find that the number-average cluster size xn governs the formation of a glassy phase as distinct from a gel phase, and that xn correlates to the size of the "cooperatively rearranging regions" postulated by the Adam-Gibbs model for glass forming liquids. These results suggest that the step polymerization process generates clusters that behave much like dynamical heterogeneities observed in supercooled liquids.

Journal Article↗
PubMed1987

CT of giant cavernous hemangioma.

Giant hepatic cavernous hemangiomas are clinically distinct from smaller asymptomatic ones and may be confused with primary or metastatic malignancy. Hemangiomas exceeding 8 cm in diameter (mean, 13.7 cm) were studied in eight women 28-71 years old, six of whom presented with right upper quadrant discomfort and/or hepatomegaly. On unenhanced CT, seven of the masses were less dense than surrounding normal liver and one was slightly more dense than adjacent fatty liver. All masses contained additional stellate or cleftlike low-density zones, and two contained calcification. After bolus IV contrast administration, all exhibited early peripheral enhancement and partial centripetal isodense fill-in. None became completely isodense on delayed scans. Familiarity with these CT characteristics and a high index of suspicion should facilitate correct diagnosis and avert needle biopsy.

Hemangioma, Cavernous↗