Intravenous (IV) levetiracetam (LEV) is available for humans for bridge therapy when the oral route is unavailable. We investigated the safety and pharmacokinetics of LEV administered intramuscularly (IM), IV, and orally to dogs.Six Hound dogs received 19.5-22.6 mg/kg of LEV IM, IV and orally with a wash-out period in between. All dogs received 500 mg LEV orally and 5 mL of 100 mg/mL LEV IM. Three dogs received 500 mg of LEV IV and three dogs received 250 mg LEV IV with 250 mg given perivascularly to approximate extravasation. Safety was assessed using a pain scale at time of IM administration and histopathological examination 24 h to 5 days after injection.Intravenous LEV half-life was 180 +/- 18 min. Bioavailability of IM LEV was 100%. Mean time to T-max after IM was 40 +/- 16 min. The mean C-max IM was 30.3 +/- 3 mu g/mL compared to the C-0 of 37 +/- 5 mu g/mL for IV. Mean inflammation score (0-4 scale) for IM LEV was 0.28 and for saline 0.62. Extravasation did not cause tissue damage.Parenteral LEV is well tolerated and appears safe following IM and IV injections in dogs. Parenteral LEV should be evaluated for use in dogs with epilepsy.

A room-temperature scanning tunneling spectroscopy study has been conducted on single molecules and multilayers of C60 molecules adsorbed on the Si(100)-(2×1) surface without any post-annealing. For single isolated molecules, four peaks in the local density of states are observed that can be well attributed to molecular energy levels. Scanning tunneling microscope spectroscopy has also been carried out on molecules that are moved across the silicon surface. Spectroscopy on multilayers of C60 shows broad, smeared out features for the first monolayer, while the third layer results resemble those of single isolated molecules. We attribute the variations in electronic spectra to differing inter-molecular interactions in the first and upper layers of C60.

The electronic transport properties of K-doped C60 mono- and multi-layers are reported with focus on the superconducting transition. The films were deposited on the 7×7 reconstructed Si(111) surface in UHV and showed a well-ordered growth structure. We have measured the electrical resistivity of films with thicknesses between 1 and 6.5 monolayers (ML) in a four-probe arrangement. All films show a semiconducting temperature dependence of the resistivity even though they are doped with 3 K atoms per C60. Nevertheless, we find a transition to a superconducting state for films as thin as 2.4 ML. Normal and superconducting properties are discussed in the context of disorder and film thickness.

The interaction of ${\mathrm{C}}_{60}$ with the Si(111)-(7\ifmmode\times\else\texttimes\fi{}7) and Si(100)-(2\ifmmode\times\else\texttimes\fi{}1) surfaces has been investigated using synchrotron radiation core-level and valence-band photoelectron spectroscopy. ${\mathrm{C}}_{60}$ induces distinct spectral changes in the $\mathrm{S}\mathrm{i}\ensuremath{-}2p$ core-level emission from both surfaces, indicative of charge transfer to the adsorbed fullerene molecules. Our results suggest that ${\mathrm{C}}_{60}$ adsorption on Si(111) induces a redistribution of charge within the (7\ifmmode\times\else\texttimes\fi{}7) unit cell involving electron transfer from rest atom to adatom dangling bonds. For a one monolayer coverage [on both Si(111) and Si(100)], broad ${\mathrm{C}}_{60}$-induced chemically shifted components are present in the core-level spectra. Valence-band spectra, however, show no evidence for a high degree of electron occupation of the ${\mathrm{C}}_{60}$ lowest unoccupied molecular orbital. We present core-level data which illustrate that adsorption of a ${\mathrm{C}}_{60}$ monolayer inhibits ambient oxidation of the Si surface.

The interaction of C60 with the (2×2) and (1×1)LT reconstructions of the GaAs(111)B surface has been studied using synchrotron radiation core-level and valence band photoemission. For the (2×2) phase, C60 adsorption produces no change in either the line-shape or the energy position of the Ga3d and As3d core-levels. In contrast, the As3d photoelectron spectrum of the (1×1)LT surface is considerably altered following the deposition of C60. Our results indicate that the character of C60 adsorption may be changed from physisorption to chemisorption via variations in surface reconstruction and stoichiometry.

We show that the tip of a scanning tunneling microscope can be used to manipulate large groups of molecules and form lines in C60 multilayers that have widths of order 10 nm and lengths up to 1 μm. This modification is achieved by first moving the tip towards the surface and then sweeping it across a predetermined distance. This causes the second and higher layers of adsorbed C60 to accumulate in ordered islands that are several layers high and leaves exposed the first C60 layer, which is partially ordered in a hexagonal arrangement. Our results show that the first adsorbed C60 layer bonds strongly to the Si(111)–7×7 surface but that higher layers are bound much more weakly and can be routinely modified.

We have investigated the decapped GaAs(311)A surface using both scanning tunneling microscopy and synchrotron-radiation photoemission. While our data are in broad agreement with the structural model of GaAs(311)A proposed in a recent study [Wassermeier et al., Phys. Rev. B 51, 14 721 (1995)], we find considerable differences in the surface order. In particular, the As dimer rows are unbroken over much shorter length scales and are highly kinked. We observe a correspondingly lower degree of anisotropy in the surface roughness than that previously reported. An (8×1) reconstruction was not observed. An analysis of As 3d and Ga 3d core-level photoemission spectra suggests that surface As atoms are in only one bonding configuration while surface Ga adopts two different bonding states. We discuss possible origins for the core-level spectra surface components.

We have demonstrated that the tip of a scanning tunnelling microscope (STM) may be used to position individual C-60 molecules on a Si(111) surface. This work is reviewed together with more recent results on STM modification of C-60 multilayers. The chemical passivation of Si(111) by a C-60 monolayer is also discussed.

The surface structures resulting from the deposition of Sb on the GaAs(111)B-(2 × 2) surface at room temperature followed by annealing, have been studied by high-resolution soft X-ray photoemission (SXPS) and low energy electron diffraction (LEED). For depositions at room temperature with no subsequent anneal and for annealing temperatures up to 300°C, Sb islands are formed between which the As trimer-based (2 × 2) substrate reconstruction of the clean GaAs surface is observed. Annealing to temperatures between 350 and 475°C leads to the creation of Sb chain pairs coexisting with regions of Sb trimers. At 500°C an ordered surface is produced, associated with Sb trimers and an As vacancy.

We have developed a procedure for atomic scale alignment with respect to macroscopic objects. Metallic and etched registration marks on clean reconstructed Si surfaces are used to guide the tip of a scanning tunnelling microscope. The metallic marks are formed from Ta and can withstand thermal cycling up to 1500 K. These procedures have been used to investigate the interaction of Ag with a patterned fullerene multilayer deposited on Si(111)-7×7.

C60 monolayers are formed on a Si(111)-7×7 surface under ultrahigh vacuum (UHV) conditions. The effects of exposure to atmosphere (for 30 min) and water (for 30 s) are assessed by comparing images of the surface acquired using an UHV scanning tunneling microscope. Following exposure and/or immersion we are able to resolve the C60 molecules exhibiting hexagonal order in an arrangement which is essentially identical to that formed prior to withdrawal from the UHV system. Our results clearly show that deposition of one monolayer of C60 on a Si surface can inhibit chemical attack by water and atmospheric oxygen.

The tip of a scanning tunnelling microscope is used to position individual C60 molecules on an Si(111)-(7 × 7) surface. The molecules may be manipulated into simple patterns and we describe in addition how a molecule may be moved over a bilayer step between two terraces. We also discuss C60 manipulation on an Si(111) surface with a submonolayer coverage of Ag.

We have used the tip of an ultrahigh vacuum scanning tunneling microscope to induce displacements of C60 molecules on the Si(111)-7×7 surface at room temperature. The manipulation is achieved by using a sweeping procedure we have developed which moves the tip closer to the surface and sweeps it across in a predetermined direction. Feedback control of the tunnel current is maintained throughout and the tip-surface separation is adjusted by changing the sample bias and tunnel current. For a 0.007 monolayer (ML) coverage of C60, a sweeping area of 60 Å×60 Å was used to move individual C60 molecules, while for higher coverages (0.05–0.2 ML) a sweeping area of 216 Å×216 Å was used to move large groups of C60 molecules. We show an example at 0.2 ML coverage where we have removed C60 over an area 110 Å×370 Å resulting in the formation of a line of C60 molecules 20–30 Å in width.

We have used an ultra-high-vacuum (UHV) scanning tunnelling microscope (STM) to image C-60 molecules adsorbed on a Si(111) 7 x 7 surface. At low coverage (similar to 0.01 monolayers) molecules are adsorbed at random sites. For coverages close to a monolayer they are partially ordered in a hexagonal arrangement. Second- and higher-layer islands, in which the C-60 molecules are clearly resolved, are observed at higher coverage. These islands may be desorbed by annealing in the range 200-300 degrees C, leaving an Si surface terminated by a C-60 monolayer. This surface is stable to exposure to air and immersion in water. in addition, recent work on manipulation of C-60 molecules at various coverages is reviewed and results relating to tip alignment in UHV are discussed.

We present scanning tunneling microscopy data illustrating the evolution of the decapped GaAs(001) surface following annealing in stages from 450 to 540 °C. After annealing at 450 °C a (2×4) reconstruction is formed by kinked rows of two As dimer unit cells. Following annealing in the 475–500 °C range small isolated regions of (4×2) reconstruction are visible, with a considerable increase in disorder of the remaining (2×4) reconstructed areas. Annealing at higher temperatures causes the (4×2) structure to become increasingly dominant. We have noted significant differences in the surface morphology as a function of annealing time. Our images of the (4×2) surface are similar to those recently reported by other groups but we propose a new structural model.

We have used the tip of a scanning tunneling microscope to position individual C60 molecules on a Si(111) surface. It is possible to form simple patterns of molecules at room temperature using this technique.

Chemischer InformationsdienstVolume 11, Issue 51 Natural Products ChemInform Abstract: ACID- AND BASE-CATALYZED ISOMERIZATION OF ANDROST-5-ENE-3,17-DIONE AND 17α-ETHYNYL-17β-HYDROXY-5(10)-ESTREN-3-ONE S. K. PERERA, S. K. PERERASearch for more papers by this authorW. A. DUNN, W. A. DUNNSearch for more papers by this authorL. R. FEDOR, L. R. FEDORSearch for more papers by this author S. K. PERERA, S. K. PERERASearch for more papers by this authorW. A. DUNN, W. A. DUNNSearch for more papers by this authorL. R. FEDOR, L. R. FEDORSearch for more papers by this author First published: December 23, 1980 https://doi.org/10.1002/chin.198051299Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume11, Issue51December 23, 1980 RelatedInformation