Rigorous constructive solution to monodimensional poiseuille and thermal creep flows

Summary A rigorous constructive method is discussed for solving the linear integral equations which govern either the Poiseuille flow and the thermal creep flow of a rarefied gas between parallel plates. In both cases numerical results are presented for the nondimensionalized mass flow rate, and for certain quantities which are closely related to the mass and slip velocities. Critical comparison with previous results is made wherever possible.

---

Sommario Nella nota viene discusso un rigoroso metodo costruttivo per risolvere le equazioni integrali lineari che regolano sia il moto di Poiseuille che il moto di scorrimento termico di un gas rarefatto fra due piastre piane parallele. Per ambedue le situazioni fisiche vengono presentati vari risultati numerici connessi con la portata e con le velocità. Dove possibile, i risultati ottenuti sono confrontati con quelli disponibili nella letteratura.

     

DFT study of conformational and spectroscopic properties of yatakemycin

Molecular structure and conformational preferences of yatakemycin, a novel and exceptionally potent antitumor agent, have been investigated using the density functional theory (DFT) formalism. From the relative stability of various possible conformations, it is found that two conformers are nearly isoenergetic and markedly more stable than the others in the gas phase. To test the effect of polar mediums, the relative energies have been recalculated using the self-consistent reaction field method. Thus, the most stable conformer of the isolated molecule in the gas phase is expected to be still more preferred in solution. The molecular structure of yatakemycin has also been studied by means of its spectroscopic properties. The DFT results satisfactorily reproduce the experimental data and corroborate the reliability of the structural characterization advanced for yatakemycin. The lowest-energy electronic transitions have been interpreted with time-dependent DFT calculations. Notably, the strong IR band observed at 2852 cm(-1) is unambiguously assigned to the O-H stretching of the (C7)O-H...O(C12) fragment, linked by a strong intramolecular H-bond, and may be viewed as a distinctive fingerprint of yatakemycin. Furthermore, the calculated set of NMR chemical shifts of carbonyl carbon atoms and indole protons, the most sensitive to stereoelectronic factors, is consistent with experiment. The effects of both protonation and oxidation on the geometry of the most stable conformer have also been studied. With reference to yatakemycin's DNA alkylation properties, the structure of the yatakemycin-adenine adduct has been theoretically modeled and found to be consistent with experimental spectroscopic evidence.     

Quality of Service Measurements over an Optical GMPLS Wide Area Access Network

The introduction of intelligence for management and control of optical networks based on internet protocol and the quality of service (QoS) are key issues for the evolution of the next generation network. In this paper the authors report experimental results on QoS measurements related to different real time multimedia services in an optical network based on a ring configuration obtained by means of the fibers contained in an installed cable between Rome and Pomezia, core routers with optical Gigabit Ethernet interfaces and configured with differentiated service over multi-protocol label switching architecture.     

On the structure of Borel stable abelian subalgebras in infinitesimal symmetric spaces

Let ${\mathfrak{g}=\mathfrak{g}^{\bar 0}\oplus \mathfrak{g}^{\bar 1}}$ be a ${\mathbb{Z}_2}$ -graded Lie algebra. We study the posets of abelian subalgebras of ${\mathfrak{g}^{\bar 1}}$ which are stable w.r.t. a Borel subalgebra of ${\mathfrak{g}^{\bar 0}}$ . In particular, we find a natural parametrization of maximal elements and dimension formulas for them. We recover as special cases several results of Kostant, Panyushev, and Suter.     

Toward a stable α-cycloalkyl amino acid with a photoswitchable cationic side chain

The N-alkylated indanylidenepyrroline (NAIP) Schiff base 3 is an unnatural α-amino acid precursor potentially useful for the preparation of semisynthetic peptides and proteins incorporating charged side chains whose structure can be modulated via Z/E photoisomerization. Here we report that the heteroallylic protons of 3 led to partial loss of ethanol accompanied by formation of the novel heterocyclic system 4 during attempted deprotection. We also show that the same protons catalyze the thermal isomerization of 3, making the light-driven conformational control concept ineffective for times longer than a few hours. These problems are not present in the previously unreported compound 5 where the acidic methyl group is replaced by an H atom. Therefore, 5, rather than 3, constitutes a promising prototype for the design of building blocks capable to modulate the electrostatic potential of a protein in specific locations via light irradiation.     

Expression of a Chitinase Gene from <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> in Tobacco Plants Confers Resistance against <Emphasis Type="Italic">Rhizoctonia solani</Emphasis>

The chit1 gene from the entomopathogenic fungus Metarhizium anisopliae, encoding the endochitinase CHIT42, was placed under the control of the CaMV 35S promoter, and the resulting construct was transferred to tobacco. Seventeen kanamycin-resistant transgenic lines were recovered, and the presence of the transgene was confirmed by polymerase chain reactions and Southern blot hybridization. The number of chit1 copies was determined to be varying from one to four. Copy number had observable effects neither on plant growth nor development. Substantial heterogeneity concerning production of the recombinant chitinase, and both general and specific chitinolytic activities were detected in leaf extracts from primary transformants. The highest chitinase activities were found in plants harboring two copies of chit1 inserts at different loci. Progeny derived from self-pollination of the primary transgenics revealed a stable inheritance pattern, with transgene segregation following a mendelian dihybrid ratio. Two selected plants expressing high levels of CHIT42 were consistently resistant to the soilborne pathogen Rhizoctonia solani, suggesting a direct relationship between enzyme activity and reduction of foliar area affected by fungal lesions. To date, this is the first report of resistance to fungal attack in plants mediated by a recombinant chitinase from an entomopathogenic and acaricide fungus.     

UPS, XPS, and NEXAFS study of self-assembly of standing 1,4-benzenedimethanethiol SAMs on gold

We report a study of the self-assembly of 1,4-benzenedimethanethiol monolayers on gold formed in n-hexane solution held at 60 °C for 30 min and in dark conditions. The valence band characteristics, the thickness of the layer, and the orientation of the molecules were analyzed at a synchrotron using high resolution photoelectron spectroscopy and near edge X-ray adsorption spectroscopy. These measurements unambiguously attest the formation of a single layer with molecules arranged in the upright position and presenting a free -SH group at the outer interface. Near edge X-ray absorption fine structure (NEXAFS) measurements suggest that the molecular axis is oriented at 24° with respect to the surface normal. In addition, valence band features could be successfully associated to specific molecular orbital contributions thanks to the comparison with theoretically calculated density of states projected on the different molecular units.     

Studies of the interface of conducting polymers with inorganic surfaces

Many of the properties of multi-material systems and relevant devices depend on the interfaces between the different components. This review focuses on characterization of the interfaces between intrinsically conducting polymers and inorganic materials consisting of metals and metal oxides. These materials are chosen because of their importance in several analytical applications. Although use of conducting polymers and metals or metal oxides in analytical systems, specifically in sensing, is well established, the number of novel materials used for analytical purposes is continuously increasing. This further increases the possible number of effective combinations of different materials within multicomponent systems. As a consequence, innovative characterization techniques have become as important as more conventional techniques. On the other hand, sophisticated characterisation techniques are increasingly widespread and, consequently, also readily accessible. This critical review is not an exhaustive discussion of all possible analytical techniques suitable for characterization of interfaces. It is, instead, limited to an overview of the most effective, relatively widespread techniques, emphasising their most significant recent advances. Critical analysis of the individual techniques is complemented by a few selected examples.     

Synthesis,characterization and X-ray crystal structure of the trigonal-planar copper(I) complex [Cu(MIBI)3] (MIBI = 2-methoxyisobutylisocyanide)

The synthesis, spectroscopic and chromatographic characterization, and X-ray crystal structure of the complex tris(2-methoxyisobutylisocyano) copper(I) tetrafluoroborate, [Cu(MIBI)₃][BF₄], is reported. The Cu atom lies on threefold axis and is bonded to three 2-methoxyisobutylisocyano ligands in a perfect trigonal-planar coordination. The calculated and experimental powder-diffraction spectra of this complex are also reported.