All-optical add-drop node for optical packet-switched networks

We have demonstrated all-optical packet add-drop for all-optical packet-switched networks. Intelligent all-optical add-drop of packets is performed, based on all-optical processing of packet headers. The header and payload rates are 5 and 10 Gbits/s, respectively.     

Separation of proteins on surface-modified poly(dimethylsiloxane) microfluidic devices

Separation and detection of proteins have been realized on nonionic surfactant-modified poly(dimethylsiloxane) (PDMS) microfabricated devices with end-column amperometric detection. The hydrophobic PDMS channels are turned into hydrophilic ones after being modified with Brij35 and facilitate the separation of proteins. The coating can remarkably reduce the adsorption of large protein molecules and is stable in the range of pH 6-12. The detection of proteins in such channels needs less rinsing time and thus efficiency is raised. Even large molecules of proteins can also be detected with better reproducibility and enhanced plate numbers. The relative standard deviation (RSD) of the migration time for glucose oxidase (GOD) is 2.2% (n = 19). Separation of GOD and myoglobin has been developed in modified channels. Predominant operational variables, such as the coating conditions, the concentration of surfactant and buffer, are studied in detail.     

Spectrophotometric determination of deacetylation degree of chitinous materials dissolved in phosphoric acid

A simple spectrophotometric method is proposed for determining deacetylation degrees (DD) of chitinous materials using phosphoric acid as the UV-transparent solvent system. Calibrating by the extinction coefficients (A(210)) of D-glucosamine and N-acetyl-D-glucosamine, DD values (24-88%) were computed numerically. The results correlated well (R(2) = 0.9805, n = 50) with those obtained by solid-state (13)C NMR. Comparison of the results obtained by the proposed UV method and solid-state (13)C NMR.     

Proteomic analysis of human cerebral cortex in epileptic patients

Epilepsy affects more than 0.5% of the world population and is known to be associated with a large genetic component eliciting an electrical hyperexcitability in the central nervous system. However, its pathogenic mechanisms remain poorly understood. In order to gain greater molecular incite in the pathogenesis in epilepsy, we analyzed proteomes of human cerebral cortices. Quantitative proteome analysis was used to compare signals corresponding to individual proteins between epileptic cerebral cortices from patients with temporal lobe epilepsy and age-matched non-epileptic subjects. To minimize individual variations, gender and age of the patients were matched. Changes of several spots were consistent among 6 pairs of epileptic patients and nonepileptic subjects. One of the spots was identified as the mitochondrial type Mn-superoxide dismutase (Mn-SOD) confirmed by Western blot analysis with Mn-SOD antibody and enzyme activity assay. Such results were agreeable with chemical and physical parameters given by the 2-dimensional electrophoresis (2-DE) gel. Mn-SOD was consistently down-regulated in epileptic cerebral cortices compared with those of nonepileptic subjects. Our results demonstrate a clear link between pathogenesis of epilepsy and SOD. Additionally, we identified four proteins that were consistently over-expressed in all epileptic temporal neocortices specimens and the other four proteins that were found to be expressed less than non-epileptic control subjects. These proteomic data provide cellular markers in the understanding mechanism of the epilepsy pathogenesis.     

Quantitative comparison of kinetic stabilities of metallomacrocycle-based rotaxanes

Four mononuclear metallomacrocycles with identical cavities but different transition metals (Os(VI), Pd(II), Pt(II), and Re(I)) were prepared. With these metallomacrocycles, the corresponding rotaxanes 2-Os, 2-Pd, 2-Pt, and 2-Re were self-assembled by hydrogen-bonding interactions. The kinetic stabilities of the rotaxanes were determined quantitatively and compared with each other by (1)H NMR spectroscopic techniques, including two-dimensional exchange spectroscopy (2D-EXSY) experiments. The activation free energies (DeltaG( not equal )) for the exchange between the rotaxanes 2-Os, 2-Pd and 2-Pt and their free components were determined to be 15.5, 16.0, and 16.4 kcal mol(-1), respectively. These magnitudes imply that the rotaxanes 2-Os, 2-Pd and 2-Pt are kinetically labile at room temperature and exist only as equilibrium mixtures with free components in solution. In contrast, the rotaxane 2-Re is kinetically stable enough to be isolated in pure form by silica gel chromatography under ordinary laboratory conditions. However, at higher temperatures (>60 degrees C) 2-Re was slowly disassembled into its components until the equilibrium was established. The rate constants were measured at three different temperatures, and the Eyring plot yielded the activation enthalpy DeltaH(not equal)=35 kcal mol(-1) and the activation entropy DeltaS(not equal)=27 eu for the disassembly of the rotaxane 2-Re in Cl(2)CDCDCl(2). These thermodynamic parameters gave the activation free energy DeltaG(not equal)(off)=27.1 kcal mol(-1) at 25 degrees C. Consequently, 2-Re is one example of a novel metallomacrocycle-based rotaxane that contains a coordination bond with enough strength to allow both for isolation in pure form around room temperature and for self-assembly at higher temperatures.     

Lasonolide A: structural revision and total synthesis

The proposed structure of lasonolide A was synthesized employing radical cyclization reactions of beta-alkoxyacrylates for preparation of the tetrahydropyranyl units A and B, but the spectroscopic data did not match those of the natural product. Both enantiomers of a revised structure featuring 17E,25Z double bonds were synthesized, and the (-)-isomer was found to be the biologically active enantiomer.     

Synthesis of novel 2,6-disubstituted-3,4-dimethylidene tetrahydropyrans via Prins-type cyclization

Synthesis of novel substituted tetrahydropyrans with adjacent exo-methylene groups at the C3 and C4 positions via Prins-type cyclization has been described.     

Shear instabilities of freely standing thermotropic smectic- A films

In this Letter we discuss theoretically the instabilities of thermotropic freely standing smectic- A films under shear flow [3]. We show that, in Couette geometry, the centrifugal force pushes the liquid crystal toward the outer boundary and induces smectic layer dilation close to the outer boundary. Under strong shear, this effect induces a layer buckling instability. The critical shear rate is proportional to 1/sqrt[d], where d is the thickness of the film.