Catalyzed Knoevenagel reactions on inorganic solid supports: Application to the synthesis of coumarine compounds

Knoevenagel reactions involving carbonyl compounds and active methylene derivatives have been studied in the presence of alumina, KSF and K10 montmorillonites. With addition of water the ester group undergoes hydrolysis. A route is disclosed for the synthesis of coumarine compounds catalyzed by solid supports.     

Computational parametric analysis of fuel cells: Application to PEMFC and SOFC

This study presents a numerical investigation on the proton exchange membrane fuel cell (PEMFC) and the solid oxide fuel cell (SOFC), using the aerothermal and electrochemistry equations to describe all phenomena included in both types of the fuel cells. The computational process is based on the implementation of the mathematical fuel cells models in FLUENT computational fluid dynamics code. This is in order to evaluate the temperature field, the production of the electricity, and the distribution of the water mass fraction in different region of the fuel cells. The obtained results show that the simulation is able to evaluate the physical and chemical parameters to explain the main phenomena in the fuel cells.     

Improving FAIMS sensitivity using a planar geometry with slit interfaces

Differential mobility spectrometry or field asymmetric waveform ion mobility spectrometry (FAIMS) is gaining broad acceptance for analyses of gas-phase ions, especially in conjunction with largely orthogonal separation methods such as mass spectrometry (MS) and/or conventional (drift tube) ion mobility spectrometry. In FAIMS, ions are filtered while passing through a gap between two electrodes that may have planar or curved (in particular, cylindrical) geometry. Despite substantial inherent advantages of the planar configuration and its near-universal adoption in current stand-alone FAIMS devices, commercial FAIMS/MS systems have employed curved FAIMS geometries that can be more effectively interfaced to MS. Here we report a new planar (p-) FAIMS design with slit-shaped entrance and exit apertures that substantially increase ion transmission in and out of the analyzer. The entrance slit interface effectively couples p-FAIMS to multi-emitter electrospray ionization (ESI) sources, improving greatly the ion current introduced to the device and allowing liquid flow rates up to ∼50 μL/min. The exit slit interface increases the transmission of ribbon-shaped ion beams output by the p-FAIMS to downstream stages such as a MS. Overall, the ion signal in ESI/FAIMS/MS analyses increases by over an order of magnitude without affecting FAIMS resolution.     

Solving VLSI design and DNA sequencing problems using bipartization of graphs

In this paper we consider the 2-layer constrained via minimization problem and the SNP haplotype assembly problem. The former problem arises in the design of integrated and printed circuit boards, and the latter comes up in the DNA sequencing process for diploid organisms. We show that, for any maximum junction degree, the problem can be reduced to the maximum bipartite induced subgraph problem. Moreover we show that the SNP haplotype assembly problem can also be reduced to the maximum bipartite induced subgraph problem for the so-called minimum error correction criterion. We give a partial characterization of the bipartite induced subgraph polytope. Using this, we devise a branch-and-cut algorithm and report some experimental results. This algorithm has been used to solve real and large instances.     

Polymerization of ionized acetylene clusters into covalent bonded ions: evidence for the formation of benzene radical cation

Since the discovery of acetylene and benzene in protoplanetary nebulae under powerful ultraviolet ionizing radiation, efforts have been made to investigate the polymerization of ionized acetylene. Here we report the efficient formation of benzene ions within gas-phase ionized acetylene clusters (C2H2)n+ with n = 3-60. The results from experiments, which use mass-selected ion mobility techniques, indicate that the (C2H2)3+ ion has unusual stability similar to that of the benzene cation; its primary fragment ions are similar to those reported from the benzene cation, and it has a collision cross section of 47.4 A2 in helium at 300 K, similar to the value of 47.9 A2 reported for the benzene cation. In other words, (C2H2)3+ structurally looks like benzene, it has stability similar to that of benzene, it fragments such as benzene, therefore, it must be benzene!     

Design of survivable IP-over-optical networks

In the past years, telecommunications networks have seen an important evolution with the advances in optical technologies and the explosive growth of the Internet. Several optical systems allow a very large transport capacity, and data traffic has dramatically increased. Telecommunications networks are now moving towards a model of high-speed routers interconnected by intelligent optical core networks. Moreover, there is a general consensus that the control plan of the optical networks should utilize IP-based protocols for dynamic provisioning and restoration of lightpaths. The interaction of the IP routers with the optical core networks permits to achieve end-to-end connections, and the lightpaths of the optical networks define the topology of the IP network. This new infrastructure has to be sufficiently survivable, so that network services can be restored in the event of a catastrophic failure. In this paper we consider a multilayer survivable network design problem that may be of practical interest for IP-over-optical neworks. We give an integer programming formulation for this problem and discuss the associated polytope. We describe some valid inequalities and study when these are facet defining. We discuss separation algorithms for these inequalities and introduce some reduction operations. We develop a Branch-and-Cut algorithm based on these results and present extensive computational results.     

The Effectiveness of a Voice Treatment Approach for Teachers With Self-Reported Voice Problems

SUMMARY: Teachers are considered the professional group most at risk of developing voice-problems, but limited treatment effectiveness evidence exists. We studied prospectively the effectiveness of a 6-week combined treatment approach using vocal function exercises (VFEs) and vocal hygiene (VH) education with 20 teachers with self-reported voice problems. Twenty subjects were randomly assigned to a no-treatment control (n = 11) and a treatment group (n = 9). Fibreoptic endoscopic evaluation was carried out on all subjects before randomization. Two self-report voice outcome measures were used: the Voice-Related Quality of Life (VRQOL) and the Voice Symptom Severity Scale (VoiSS). A Voice Care Knowledge Visual Analogue Scale (VAS), developed specifically for the study, was also used to evaluate change in selected voice knowledge areas. A Student unpaired t test revealed a statistically significant (P < 0.05) improvement in the treatment group as measured by the VoiSS. There was not a significant improvement in the treatment group as measured by the V-RQOL. The difference in voice care knowledge areas was also significant for the treatment group (P < 0.05). This study suggests that a voice treatment approach of VFEs and VH education improved self-reported voice symptoms and voice care knowledge in a group of teachers.     

Facets of the balanced (acyclic) induced subgraph polytope

A signed graph is a graph whose edges are labelled positive or negative. A signed graph is said to be balanced if the set of negative edges form a cut. The balanced induced subgraph polytopeP(G) of a graphG is the convex hull of the incidence vectors of all node sets that induce balanced subgraphs ofG. In this paper we exhibit various (rank) facet defining inequalities. We describe several methods with which new facet defining inequalities ofP(G) can be constructed from known ones. Finding a maximum weighted balanced induced subgraph of a series parallel graph is a polynomial problem. We show that for this class of graphsP(G) may have complicated facet defining inequalities. We derive analogous results for the polytope of acyclic induced subgraphs.Research supported in part by the Natural Sciences and Engineering Research Council of Canada; the second author has also been supported by C.P. Rail.     

Optical properties of frustrated cholesteric liquid crystals in planar cell

ABSTRACT

We investigated the alignment director of a frustrated cholesteric liquid crystal (CLC) confined in a planar cell. Three cells with different confinement ratio (c?=?d/p) (where p is the pitch and d is the cell thickness) are prepared. Under an electric field, the CLC planar texture is transformed into a cholesteric fingerprint (CF). The results showed that CF contrast depends on c. When c?≈?2, CLC stripes are formed by a periodic CF, with a period equal to the CLC pitch. The CF is developed and slowly extended to the whole cell surface along the rubbing direction and the contrast of the grating stripes keeps unchangeable. Yet, the CLC finger borders have a different light intensity. However, when c?≈?1, the CF contrast increases with time. When c?θ between the polarizer and the CFs.     

Chromatographic analysis,antimicrobial and insecticidal activities of the essential oil of Phlomis floccosa D. Don.

The present study was conducted to investigate for the first time the chemical composition and insecticidal and antimicrobial properties of Phlomis floccosa D. Don. essential oil isolated by hydro‐distillation of its aerial parts. Qualitative and quantitative analyses of the essential oil on the basis of gas chromatography and mass spectrometry (GC/FID and GC/MS) revealed the presence of 59 organic volatiles representing 86.9% of the total constituents. The major compounds were germacrene‐D (19.7%) followed by β‐caryophyllene (15.5%), caryophyllene oxide (8.3%), hexadecenoic acid (7.9%) and carvacrol (6.1%). The broth microdilution method was conducted to test the antimicrobial activity of the essential oil against five pathogens: Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, Staphylococcus aureus, Bacillus subtilis and the yeast Candida albicans. The oil of P. floccosa D. Don. shows promising activity against the Gram‐positive bacteria S. aureus and B. subtilis and the yeast C. albicans (minimum inhibitory concentration = 625 μg.mL^?1). The effectiveness of the essential oil was assessed on both Tribolium confusum and Sitophilus zeamais pest insects and it was more pronounced against T. confusum, showing a moderate mortality of 47.5%.