A new tetracyclic triterpene from the latex of Euphorbia nerifolia

A new tetracyclic triterpene 9,19-cyclolanost-22(22'), 24-diene-3beta-ol, named as nerifoliene (2) along with euphol (1) were isolated from the fresh latex of Euphorbia nerifolia. Their structures were elucidated on the basis of spectral (IR, 1H and 13C NMR, FAB and EI Mass) data.     

Optical stimulation of neural tissue in vivo

For more than a century, the traditional method of stimulating neural activity has been based on electrical methods, and it remains the gold standard to date. We report a technological breakthrough in neural activation in which low-level, pulsed infrared laser light is used to elicit compound nerve and muscle potentials in mammalian peripheral nerve in vivo. Optically induced neural action potentials are spatially precise, artifact free, and damage free and are generated by use of energies well below tissue ablation threshold. Thus optical stimulation presents a simple yet novel approach to contact-free in vivo neural activation that has major implications for clinical neurosurgery, basic neurophysiology, and neuroscience.     

Preparative liquid chromatography

Summary Historically, liquid chromatography has been a preparative technique. Its applications have been limited, however, until a decade ago. The needs of modern chemical, pharmaceutical and biochemical industries have motivated this period of phenomenal growth which is being witnessed now. Novel packing materials, new packing technologies, and advancements in instrumentation and process technologies have appeared in rapid succession. Instruments using columns with diameters ranging from a few inches to a few feet, can be packed with efficiencies comparable or better than analytical columns having the same packing material. This permits the development of new applications covering a wide variety of problems. The empirical approach, followed until recently for the development of new applications, is being improved by insights derived from a better understanding of the theory of large concentration chromatography. With increased computer power and a greater comprehension of the theoretical aspects, a fundamental approach to design and optimization of the operating parameters is being developed. Investigation of the components of the cost of industrial production is also in its early stages. Historical trends, theoretical treatments, column technologies, operating modes and guidelines for optimization will be discussed and reviewed.     

Ultrastructural features of the peculiar filter-feeding hypotrich ciliate Uronychia transfuga

In this report, dealing with Uronychia transfuga, ultrastructural details of a member of the genus Uronychia are provided for the first time. The most interesting features appear to be: (1) the lack of an alveolar, electrondense material in the cortex. This trait distinguishes Uronychia from the members of the family Euplotidae. (2) The peculiar ciliary arrangement of the massive caudal cirri. (3) The oral membrane (OM) delimited by cytoplasmic laminae of different length; it consists of two components each one formed by semicircular sheets of cilia. The length of the cilia progressively increases from the outermost sheet to the internal one. The kinetosomes are interconnected with each other by a dense material that, proximally, forms peculiar crescent-like structures connecting the kinetosomes to the innermost cytoplasmic lamina. The two components of the OM partially overlap at the apical end; at this level their kinetosomes are interconnected by infraciliary structures. The OM components are able to close the peristomial cavity by flexing toward it and completely overlapping each other. The filter feeding mechanism of Uronychia differs from those of other ciliates and allows the ingestion of large active prey. (4) The endoral membrane, probably stichomonad, is limited to the terminal part of the oral cavity. On the whole, our observations appear consistent with the hypothesis that Uronychia should be placed in its own family.     

Population monotonicity and consistency in convex games: Some logical relations

On the domain of convex games, many desirable properties of solutions are compatible and there are many single-valued solutions that are intuitively appealing. We establish some interesting logical relations among properties of single-valued solutions. In particular, we introduce a new property, weak contribution-monotonicity, and show that this property is a key property that links other properties such as population-monotonicity, max consistency, converse max consistency, and dummy-player-out. Received: July 2002/Revised: March 2003     

Synthesis and reactions of phenylimidotrimethyl-bis(trimethylphosphine)-rhenium(V). Synthesis and X-ray crystal structure of bis(trimethylsilylmethyl)oxo-rhenium(V)-μ-oxo-tetrakis(trimethylphosphine)rhenium (I)-(trimethylsilylmethyl)dioxorhenium(V), (ReRe)

The interaction of phenylimidotrichloro bis(trimethylphosphine) with dimethylmagnesium gives the trimethyl compound, Re(NPh)Me₃(PMe₃)₂. Exchange reactions between the trichloro and trimethyl compounds are studied by ¹H nuclear magnetic resonance and the intermediates Re(NPh)Me₂Cl(PMe₃)₂ and Re(NPh)MeCl₂(PMe₃)₂ isolated.The trimethyl reacts with fluoroboric acid to give a phenylamido complex [Re(NHPh)Me₂F(PMe₃)₂]BF₄, with acetic acid to give Re(NPh)Me(CO₂Me₃)₂, and with trityltetrafluoroborate to give [Re(NPh)Me₂(PMe₃)₂]BF₄.The interaction of Re(NPh)Cl₃(PMe₃)₂ with excess of bis(trimethylsilylmethyl)magnesium and of trimethyl-phosphine in tetrahydrofuran gives an unusual tri-rhenium compound, (Me₃SiCH₂)₃(O)Re-μ-O-Re(PMe₃)₄Re(O)₂(CH₂SiMe₃) whose structure as a thf solvate, has been determined by X-ray crystallography. Crystals of the latter are monoclinic, space group P2₁/n with a = 15.512(3), b = 15.392(2), c = 21.506(4) Å, β = 100.19(2)°, Z = 4. The structure has been refined to an R of 0.07 for 5028 observed diffractometer data. The molecule is tri-nuclear with the central rhenium carrying four PMe₃ groups being bound to the second rhenium by a short ReRe bond and to the third by an asymmetric oxygen bridge. The end rhenium bound to the bridge oxygen carries two CH₂SiMe₃ groups and an oxygen atom, while the other has one CH₂SiMe₃ group and two oxygen atoms.     

Potential for microbial growth in arid subsurface sediments

To determine if bacterial populations could be increased for bioremediation of contaminants, the microbial growth arising in 200 h from the solid material from the vadose zone at an arid site after addition of water and nutrients was determined. Initial bacterial populations and activities at the site were very low. Bacteria grew in the interbed sands and silts with the higher carbon contents (0.08–1.1%), but did not respond in the basalts and interbed material with lower carbon content (undetectable). In longer term studies, to 30 d, there was evidence for bacterial activity in less than 25% of either the basalts or interbed material.