Field-modulated carrier transport in carbon nanotube transistors

We have investigated the electrical transport properties of carbon nanotube field-effect transistors as a function of channel length, gate dielectric film thickness, and dielectric material. Our experiments show that the bulk properties of the semiconducting carbon nanotubes do not limit the current flow through the metal/nanotube/metal system. Instead, our results can be understood in the framework of gate and source-drain field induced modulation of the nanotube band structure at the source contact. The existence of one-dimensional Schottky barriers at the metal/nanotube interface determines the device performance and results in an unexpected scaling behavior.     

High power all-fibered femtosecond master oscillator power amplifier at 1.56 μm

Direct amplification of output from chirped pulse oscillator (CPO) to 3.3?W of average power (pulse energy of 118?nJ in 20?ps pulse duration before compression) was achieved in a properly designed cladding pumped large mode area Er-doped fiber. Various configurations of CPO cavity with different FWHM of output spectrum and pulse duration were investigated. Fourier limit compression with 480?fs pulse duration and 32?kW peak power has been obtained for pulses with 14.8?nm FWHM spectrum. Subsequent nonlinear compression in a standard SMF-28 fiber yielded pulses as short as 145?fs.     

Access to C-protected β-amino-aldehydes via transacetalization of 6-alcoxy tetrahydrooxazinones and use for pseudo-peptide synthesis

Efficient access to masked β-amino-aldehydes was performed starting from 6-alcoxy tetrahydrooxazinone 6a–d (6-ATO). Transacetalization leads to the opening of the cycle to form either unsymmetric acetal 7 or symmetric acetals 16–18. These amino acetals are key compounds, obtained with 99% ee, which can be engaged in efficient peptide coupling. This method could easily provide peptides aldehydes or small amido aldehydes as exemplified with the formal synthesis of ent-Maraviroc.     

A general decomposition approach for multi-criteria decision trees

In this paper, we address the dynamic and multi-criteria decision-making problems under uncertainty, generally represented by multi-criteria decision trees. Decision-making consists of choosing, at each period, a decision that maximizes the decision-maker outcomes. These outcomes should often be measured against a set of heterogeneous and conflicting criteria. Generating the set of non-dominated solutions is a common approach considered in the literature to solve the multi-criteria decision trees, but it becomes very challenging for large problems. We propose a new approach to solve multi-criteria decision trees without generating the set of all non-dominated solutions, which should reduce the computation time and the cardinality of the solution set. In particular, the proposed approach combines the advantages of decomposition with the application of multi-criteria decision aid (MCDA) methods at each decision node. A generalization of the Bellman’s principle of decomposition to the multi-criteria context is put forward. A decomposition theorem is therefore proposed. Under the sufficient conditions stated by the theorem, the principle of decomposition will generate the set of best compromise strategies. Seven MCDA methods are then characterized (lexicographic, weighted sum, multi-attribute value theory, TOPSIS, ELECTRE III, and PROMETHEE II) against the conditions of the theorem of decomposition and against other properties (neutrality, anonymous, fidelity, dominance, independency), in order to confirm or infirm their applicability with the proposed decomposition principle. Moreover, the relationship between independency and temporal consistence is discussed as well as the effects of incomparableness, rank reversals, and use of thresholds. Two conjectures resulted from this characterization.     

AES chemunex ADIAFOOD detection system for Listeria spp. environmental sample testing

The ADIAFOOD Detection System for the detection of Listeria species from environmental surfaces is based on real-time PCR technology and allows rapid pathogen detection within 21 h. The strength of the ADIAFOOD technology resides in its ability to rapidly and accurately detect Listeria species present on surfaces, such as stainless steel, plastic, ceramic, and sealed concrete. The technology is easy to use and versatile.     

An ordinal sorting method for group decision-making

Several group decision-making methods were proposed with the aim to establish, from individual opinions, a collective one. However, the literature review of such methods show that, until now, few of them accept individual preferences expressed in partial pre-orders or, more generally, in preferences relational systems (p.r.s.). In addition, the majority of these methods produce a ranking on the alternative set, i.e. they concern the ranking decision-making problematic. In fact, the efforts provided to develop methods which treat, for example, the sorting problematic, remain insufficient. For these reasons, we propose in this paper an ordinal sorting method which determines, from individual p.r.s., at least one collective assignment which takes into account the relative importance of the members. If there is more than one collective assignment, an interactive procedure to reach a consensus assignment is proposed.     

Organometallic Derivatives of Cycloproparenes

The tricarbonylchromium complex of cyclopropa[b]naphthalene ( 3a ) is deprotonated at C(1) with BuLi. Quenching of the resulting anion with Mel results in a 1:1 mixture of stereoisomeric methyl derivatives 6a and 6b . Peterson olefination of the bis-silylated complex 3b affords the complexed alkylidenecycloproparene 5 in low yield. The tricarbonylchromium complex of cyclopropa[b]anthracene ( 10 ) is accessible via bis-hydro-desilylation of 9 . Its X-ray structure is also reported. All attempts to synthesize a tricarbonylchromium complex of benzocyclopropene ( 11a ) failed.     

Measurement of acoustic modes of vibration in 1-methylthymine by neutron scattering

Coherent inelastic neutron scattering results have been obtained from a single crystal of hydrogenous (hydrogen content 44 at.%) 1-methylthymine. The results have been directly interpreted as acoustic phonons and effective elastic constants determined at 150 and 296 K.     

Cages, baskets, ladders, and tubes: conformational studies of polyhedral oligomeric silsesquioxanes

The conformational flexibility of a series of cage, basket, ladder, and tube polyhedral oligomeric silsesquioxanes (POSS) has been examined using the Low Mode:Monte Carlo conformational search method in conjunction with the MM3/GBSA(CHCl3) surface. An ensemble of low energy structures was generated and used to explore the molecular shape and flexibility of each system. The results indicate that, except for the ladder molecule, the incompletely condensed systems that are studied are relatively rigid. Even in cases where the molecule is able to adopt numerous low energy conformations, the overall shape remains cage-like and the conformations differ only by small angles or substituent orientations. The ladder molecule is the most flexible and this ensemble clusters into two families: one that is cage-like and the other that is more open and ladder-like. The conformational flexibilities in the gas and solvent phases, as approximated using the GBSA continuum solvent model, are very similar.     

A C-glycoside route to leukotrienes

The stereospecific syntheses of three isomers of 7-hydroxy-5,6-epoxy heptanoic acid methyl ester, $\text{7}$, $\text{12b}$ and $\text{19}$, have been achieved via a $\text{C}$-glycoside route.