Exploiting sp2‐Hybridisation in the Development of Potent 1,5‐α‐l‐Arabinanase Inhibitors

The synthesis of potent inhibitors of GH93 arabinanases as well as a synthesis of a chromogenic substrate to measure GH93 arabinanase activity are described. An insight into the reasons behind the potency of the inhibitors was gained through X‐ray crystallographic analysis of the arabinanase Arb93A from Fusarium graminearum. These compounds lay a foundation for future inhibitor development as well as for the use of the chromogenic substrate in biochemical studies of GH93 arabinanases.     

Porous NIR Photoluminescent Silicon Nanocrystals‐POSS Composites

Near infrared photoluminescent porous silicon nanocrystals(ncSi)‐polyhedral oligomeric silsesquioxanes (POSS) polymer composites are synthesized using a combination of thermal hydrosilylation and polymerization between Vinyl‐POSS and hydrogen‐terminated silicon nanocrystals (ncSi:H). The synthesized materials are characterized by IR, powder X‐ray diffraction and solid‐state nuclear magnetic resonance (NMR) (¹³C and ²⁹Si). The results demonstrate that the hydrosilylation–polymerization reaction proceeded to create chemically crosslinked Vinyl‐POSS‐ncSi composites in which the integrity of the POSS cages is maintained intact. Scanning electron microscope (SEM) results demonstrate that morphology of these materials depends on the weight ratio of ncSi:H to Vinyl‐POSS. Brunauer–Emmett–Teller surface area analyses establish that the composites have high surface areas ranging from 290.5 to 1047.2 m² g^?1 and pore volumes from 0.64 to 1.17 cm³ g^?1. The pore sizes range from 6.08 to 3.54 nm and are dependent on the weight ratio of Vinyl‐POSS to ncSi:H. Photoluminescence spectroscopy shows that the absolute quantum yield of the nanocomposites is not affected by the weight ratio of ncSi:H to Vinyl‐POSS. Thermal gravimetric analysis results show that the POSS polymer composites with ncSi have lower thermal stability in nitrogen atmosphere as compared with the pure Vinyl‐POSS polymer. It is envisioned that future applications for these composites will likely be found in the fields of advanced materials, gas adsorption media, and biomedicine.     

Cyclophilin A Is Not Acetylated at Lysine-82 and Lysine-125 in Resting and Stimulated Platelets

Cyclophilin A (CyPA) is widely expressed by all prokaryotic and eukaryotic cells. Upon activation, CyPA can be released into the extracellular space to engage in a variety of functions, such as interaction with the CD147 receptor, that contribute to the pathogenesis of cardiovascular diseases. CyPA was recently found to undergo acetylation at K82 and K125, two lysine residues conserved in most species, and these modifications are required for secretion of CyPA in response to cell activation in vascular smooth muscle cells. Herein we addressed whether acetylation at these sites is also required for the release of CyPA from platelets based on the potential for local delivery of CyPA that may exacerbate cardiovascular disease events. Western blot analyses confirmed the presence of CyPA in human and mouse platelets. Thrombin stimulation resulted in CyPA release from platelets; however, no acetylation was observed—neither in cell lysates nor in supernatants of both untreated and activated platelets, nor after immunoprecipitation of CyPA from platelets. Shotgun proteomics detected two CyPA peptide precursors in the recombinant protein, acetylated at K28, but again, no acetylation was found in CyPA derived from resting or stimulated platelets. Our findings suggest that acetylation of CyPA is not a major protein modification in platelets and that CyPA acetylation is not required for its secretion from platelets.     

Treatment of odorous sulphur compounds by chemical scrubbing with hydrogen peroxide--stabilisation of the scrubbing solution

To slow down the hydrogen peroxide decomposition in basic aqueous conditions, the addition of stabilizers and co-stabilizers in the scrubbing solution was investigated. Results found with sodium silicate (Na2SiO3) were quite promising but several problems still remained. Based on these observations, this study focused on the research of a better stabilizer. Several ways were investigated: the use of silicate solutions employed in pulp industries, the addition of co-stabilizers to sodium silicate, or the use of an another stabilizer (the poly-alpha-hydroxyacrylic acid). Experiments revealed that the poly-alpha-hydroxyacrylic acid is the best stabilizing compound.     

Ozonation effect on natural organic matter adsorption and biodegradation - Application to a membrane bioreactor containing activated carbon for drinking water production

More stringent legislation on dissolved organic matter (DOM) urges the drinking water industry to improve in DOM removal, especially when applied to water with high dissolved organic carbon (DOC) contents and low turbidity. To improve conventional processes currently used in drinking water treatment plants (DWTPs), the performances of a hybrid membrane bioreactor containing fluidised activated carbon were investigated at the DWTP of Rennes. Preliminary results showed that the residual DOC was the major part of the non-biodegradable fraction. In order to increase the global efficiency, an upstream oxidation step was added to the process. Ozone was chosen to break large molecules and increase their biodegradability. The first step consisted of carrying out lab-scale experiments in order to optimise the necessary ozone dose by measuring the process yield, in terms of biodegradable dissolved organic carbon (BDOC). Secondly, activated carbon adsorption of the DOC present in ozonated water was quantified. The whole process was tested in a pilot unit under field conditions at the DWTP of Rennes (France). Lab-scale experiments confirmed that ozonation increases the BDOC fraction, reduces the aromaticity of the DOC and produces small size organic compounds. Adsorption tests led to the conclusion that activated carbon unexpectedly removes BDOC first. Finally, the pilot unit results revealed an additional BDOC removal (from 0.10 to 0.15 mg L⁻¹) of dissolved organic carbon from the raw water considered.     

Semantic contextual cuing and visual attention.

Since M. M. Chun and Y. Jiang's (1998) original study, a large body of research based on the contextual cuing paradigm has shown that the visuocognitive system is capable of capturing certain regularities in the environment in an implicit way. The present study investigated whether regularities based on the semantic category membership of the context can be learned implicitly and whether that learning depends on attention. The contextual cuing paradigm was used with lexical displays in which the semantic category of the contextual words either did or did not predict the target location. Experiments 1 and 2 revealed that implicit contextual cuing effects can be extended to semantic category regularities. Experiments 3 and 4 indicated an implicit contextual cuing effect when the predictive context appeared in an attended color but not when the predictive context appeared in an ignored color. However, when the previously ignored context suddenly became attended, it immediately facilitated performance. In contrast, when the previously attended context suddenly became ignored, no benefit was observed. Results suggest that the expression of implicit semantic knowledge depends on attention but that latent learning can nevertheless take place outside the attentional field. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A new family of beta-hairpin mimetics based on a trypsin inhibitor from sunflower seeds

The ability of proteases to regulate many aspects of cell function and defense accounts for the considerable interest in the design of novel protease inhibitors. There are many naturally occurring proteinaceous serine protease inhibitors, one of which is a 14 amino acid cyclic peptide from sunflower seeds that shows both sequence and conformational similarity with the trypsin-reactive loop of the Bowman-Birk family of serine protease inhibitors. This inhibitor adopts a beta-hairpin conformation when bound at the active site of bovine beta-trypsin. We illustrate here an approach to inhibitor design in which the beta hairpin from the naturally occurring peptide is transplanted onto a hairpin-inducing template. Two mimetics with the sequences RC*TKSIPPIC*F (where C*C* is a disulfide) and TKSIPPI are studied, each mounted onto a D-Pro-L-Pro template. NMR studies revealed a well-defined beta-hairpin conformation for each mimetic in aqueous solution; this conformation is closely related to the trypsin-bound conformation of the natural inhibitor and includes a cis-Ile-Pro peptide bond. Both mimetics inhibit trypsin in the mid nanomolar range. An alanine scan revealed the importance for inhibitory activity of the specificity-determining Lys residue and of the first but not the second Pro residue in the IPPI motif. Since these hairpin mimetics can be prepared by parallel combinatorial synthesis, this family of molecules may be a useful starting point for the discovery of other biologically or medicinally useful serine protease inhibitors.     

A SINGLE-STAGE, LIQUID-PHASE DIMETHYL ETHER SYNTHESIS PROCESS FROM SYNGAS III. DUAL CATALYST CRYSTAL GROWTH, DEACTIVATION, AND ACTIVITY CONSERVATION STUDIES

In the liquid phase dimethyl ether (DME) synthesis process, both the methanol synthesis catalyst )composed of CuO, ZnO, and Al₂O₃) and the methanol dehydration catalyst (composed of gamma-alumina) are slurried in the inert oil phase. Various long-term activity checks were conducted on these dual catalysts to characterize the crystal growth and the thermal aging behavior. X-ray powder diffraction, X-ray fluorescence and elemental intensity compositions, and the crystallite size distributions of the aged catalysts were examined. Based on the current investigation, it was established that the crystal growth and the catalyst deactivation problems in the methanol synthesis catalyst are less severe when it is used along with the methanol dehydration catalyst.