Structure and viscosity of phase‐separated BaO–SiO2 glasses

Barium silicate glasses with 0‐40 mol% BaO were synthesized either by aerodynamical levitation and laser heating (at low barium content) or by conventional melting and quenching process. Characterization by means of Raman scattering spectroscopy and scanning transmission electron microscopy reveals a structural transition between glasses with low BaO content (<10 mol%) showing an atomic network resembling the one of amorphous silica, and glasses with a BaO content larger than 10 mol%, which exhibit the typical signature of a binary silicate glass with Q₂ and Q₃ units. Viscosity curves show a marked increase of the viscosity as the BaO content decreases below 20 mol%. Barium is found to easily diffuse and promote phase separation while silicon remains homogeneously distributed. A dramatic increase in the viscosity is observed as phase separation proceeds, resulting in the formation of Ba‐rich nodules in a percolating SiO₂‐rich matrix at low barium content, or in Ba‐poor nodules in a BaO‐rich matrix at large barium content.     

New Disaccharide‐Based Ether Lipids as SK3 Ion Channel Inhibitors

The SK3 potassium channel is involved in the development of bone metastasis and in the settlement of cancer cells in Ca²⁺‐rich environments. Ohmline, which is a lactose‐based glycero‐ether lipid, is a lead compound that decreases SK3 channel activity and consequently limits the migration of SK3‐expressing cells. Herein we report the synthesis of three new ohmline analogues in which the connection of the disaccharide moieties (1→6 versus 1→4) and the stereochemistry of the glycosyl linkage was studied. Compound 2 [3‐(hexadecyloxy)‐2‐methoxypropyl‐6‐O‐α‐d ‐glucopyranosyl‐β‐d ‐galactopyranoside], which possesses an α‐glucopyranosyl‐(1→6)‐β‐galactopyranosyl moiety, was found to decrease SK3 current amplitude (70 % inhibition at 10 μm ), displace SK3 protein outside caveolae, and decrease constitutive Ca²⁺ entry (50 % inhibition at 300 nm ) and SK3‐dependent cell migration (30 % at 300 nm ) at a level close to that of the benchmark compound ohmline. Compound 2 , which decreases the activity of SK3 channel (but not SK2 channel), is a new drug candidate to reduce cancer cell migration and to prevent bone metastasis.     

Pressureless sintered silicon carbide tailored with aluminium nitride sintering agent

This study reports the influence of aluminium nitride on the pressureless sintering of cubic phase silicon carbide nanoparticles (β-SiC). Pressureless sintering was achieved at 2000 °C for 5 min with the additions of boron carbide together with carbon of 1 wt% and 6 wt%, respectively, and a content of aluminium nitride between 0 and 10 wt%. Sintered samples present relative densities higher than 92%. The sintered microstructure was found to be greatly modified by the introduction of aluminium nitride, which reflects the influence of nitrogen on the β-SiC to α-SiC transformation. The toughness of sintered sample was not modified by AlN incorporation and is relatively low (around 2.5 MPa m^1/2). Materials exhibited transgranular fracture mode, indicating a strong bonding between SiC grains.     

Effects of the Surface Densities of Glycoclusters on the Determination of Their IC50 and Kd Value Determination by Using a Microarray

Pseudomonas aeruginosa (PA) is an opportunistic bacterium involved in 10–30 % of nosocomial diseases. It causes severe lung injury to cystic fibrosis patients, often leading to patient death. PA strains are multidrug resistant, thus making the design of new therapeutics a challenge for public health. One promising therapeutic option is to design glycoclusters that target the virulence factor of PA. LecA is a galactose‐specific lectin that might be involved in adhesion and biofilm formation by PA. The DNA‐directed immobilization (DDI) microarray is a powerful tool for screening and understanding of structure–activity relationships between glycoclusters and lectins. High‐throughput and multiplexed analysis of lectin–glycocluster interactions on a DDI microarray allows measurement of IC₅₀ and dissociation constant (K_d) values with minute amounts of material. In order to study the robustness of the DDI microarray in determination of IC₅₀ and K_d values, the impact of glycocluster surface density was investigated. The data obtained show that measured IC₅₀ values were influenced by glycocluster surface density: as the density of glycoclusters increases, the measured IC₅₀ values increase too. In contrast, the measured K_d values were not affected by glycocluster surface density, provided that the experimental conditions allow interaction between glycocluster and lectin at single‐molecule level (no surface cluster effect).     

Calculation of Photo-Ionisation Cross Sections and Radiative Recombination Rate Coefficients for CO and CO+ Molecules

A method based upon the weighted total cross section （WTCS） theory is proposed to calculate the photo-ionisation cross sections and the radiative recombination rate coefficients between the fundamental level of CO and the main electronic states of its corresponding ion. Total photo-ionisation cross sections and radiative recombination rate coefficients are determined from the calculation of elementary vibrational photo-ionisation cross sections. Transitions be- tween CO＋（X, A and B） and CO（X） are considered. Total photo-ionisation cross sections and recombination coefficients are computed in the temperature interval 500-15000 K.     

A 4 Gsample/s 2 bits flash ADC with 2–4 GHz input bandwidth for radio astronomy applications

This paper presents the design and the measurement results of a high speed A/D converter (ADC or digitizer) developed for radio-astronomy applications and especially for the ALMA (Atacama Large Millimeter Array) project. This monolithic digitizer is implemented in a BiCMOS 0.35 μm SiGe process for high frequency mixed-signal applications. The main characteristics of this circuit are a 2 bits resolution with 3 quantization levels (equivalent to 1.5 bits) with 4 Gsample/s rate, a wide input bandwidth from 2 GHz up to 4 GHz under full Nyquist condition. The adopted digitizer architecture is that of a conventional flash analog to digital converter structure. The overall chip dissipates 652 mW under ± 1.25 V supply and the die area is 5.4 mm².     

Elastic behaviour of RbHSeO4 at the superionic phase transition investigated by brillouin scattering

Brillouin investigations have been performed over the temperature range 160-200°C, which includes the superionic phase transition near ~178°C. Strong discontinuities are obtained for the three elastic constants C_ll, C₂₂ and C₃₃ at the superionic transition. In the superionic phase, two longitudinal Brillouin doublets can be observed for every direction of the acoustic wave vector. This fact can be attributed to the presence of two kinds of regions above the transition. Besides, systematic broadenings of these longitudinal lines are observed in the superionic phase. The results are qualitatively discussed in connection with theoretical expectations.     

Principles of Chemical Programming

The chemical reaction metaphor describes computation in terms of a chemical solution in which molecules interact freely according to reaction rules. Chemical models use the multiset as their basic data structure. Computation proceeds by rewritings of the multiset which consume elements according to reaction conditions and produce new elements according to specific transformation rules. Since the introduction of Gamma in the mid-eighties, many other chemical formalisms have been proposed such as the Cham, the P-systems and various higher-order extensions. The main objective of this paper is to identify a basic calculus containing the very essence of the chemical paradigm and from which extensions can be derived and compared to existing chemical models.     

Towards Efficient, Typed LR Parsers

The LR parser generators that are bundled with many functional programming language implementations produce code that is untyped, needlessly inefficient, or both. We show that, using generalized algebraic data types, it is possible to produce parsers that are well-typed (so they cannot unexpectedly crash or fail) and nevertheless efficient. This is a pleasing result as well as an illustration of the new expressiveness offered by generalized algebraic data types.     

Design of multi-terabit/s terrestrial transmission systems facilitated by simple analytical tools

For 30 years, the capacity distance product of lightwave communication systems has continuously doubled every 16 months, to reach more than 10 Pbit/s.km in 2002. Along with this growth, the complexity of system engineering has increased as linear and nonlinear transmission impairments have become more stringent. Dispersion management is widely accepted as a powerful technique to mitigate some of them, but requires numerous experiments or time-consuming numerical simulations to be performed optimally. We exhibit two analytical rules that provide meaningful insight on this matter. Then we show how these rules helped us to improve the transmission distance of a recent 5 Tbit/s transmission experiment from 1,200 km to 1,500 km.