Dilip K. Sensharma

The Higher Fullerenes: Isolation and Characterization of C76, C84, C90, C94, and C70O, an Oxide of D5h-C70.

The toluene extract of the fluffy carbon material produced by resistive heating of graphite contains a variety of molecules larger than C60 and C70 in a total amount of 3 to 4% by weight. Repeated chromatography of this material on neutral alumina has led to the isolation of stable solid samples of C76, C84, C90, and C94. The characterization, which includes mass spectrometry, 13C nuclear magnetic resonance, electronic absorption (ultraviolet/visible) and vibrational (infrared) spectroscopy identifies these all-carbon molecules as higher fullerenes. In addition, C70O, a stable oxide, has been isolated that is structurally and electronically closely related to D5h-C70. This compound forms during the resistive heating process and probably has an oxygen atom inserted between two carbon atoms on the convex external surface of the C70 skeleton.

Kinetic energy release distribution and the mechanism for evaporation of one and two CsI molecules from sputtered Cs(CsI)n+ clusters

Abstract The average kinetic energy release (KER) and the peak shape constant, representing the KER distribution, are determined for the metastable peaks resulting from the evaporation of one and two CsI molecules from sputtered Cs(CsI) n + clusters. Results suggest that the evaporation of two CsI molecules involves a direct fission rather than a sequential process. The observed difference in the shape of the KER distribution between the two evaporation channels can best be accounted for by the difference in the type of long range interaction, implying that the evaporating CsI dimer has a near zero dipole moment.

Na-K-ATPase inhibitor dissociated from hypertension-associated plasma protein

It has been demonstrated that human plasma contains a low molecular weight sodium-potassium-stimulated adenosine triphosphatase (Na-K-ATPase) inhibitor, which can be dissociated from a circulating protein with a molecular weight of approximately 12,000 daltons. The dissociated factor was found to have a molecular weight <500 daltons, and shared many characteristics with ouabain. Similar to ouabain, this factor was found to be a potent inhibitor of both the Na-K-ATPase and potassium-stimulated para-nitrophenyl phosphatase (K-pNPPase) enzyme systems, and to bind to both high- and low-affinity binding sites on Na-K-ATPase, but unlike ouabain did not cross-react with digoxin antibody. The factor was further separated by HPLC and electrochemical detection into two active compounds (p-NKAI-1 and p-NKAI-2). P-NKAI-1 was demonstrated on mass spectroscopy to have a molecular weight of 408 daltons. In a vasoconstrictor assay employing rabbit femoral artery segments, this compound was a direct vasoconstrictor and potentiated the vasoconstriction produced by norepinephrine. It behaved similarly to ouabain in counteracting the relaxing effect on rabbit femoral artery of increasing potassium concentrations in the tissue bath.