Active control of the depletion boundary layers in microfluidic electrochemical reactors

In this paper, we describe three methods to improve the performance of pressure-driven laminar flow-based microreactors by manipulating reaction-depletion boundary layers to overcome mass transfer limitations at reactive surfaces on the walls, such as electrodes. The transport rate of the reactants to the reactive surfaces is enhanced by (i) removing the depleted zone through multiple periodically-placed outlets; (ii) adding fresh reactants through multiple periodically-placed inlets along the reactive surface; or (iii) producing a spiraling, transverse flow through the integration of herringbone ridges along the channel walls. For approaches (i) and (ii), the network of microfluidic channels needs to be designed such that under the operating conditions used the right amount of boundary layer at each outlet or inlet is removed or replenished, respectively. Here, we report a set of design rules, derived with the help of a fluidic resistance circuit model, to aid in the design of appropriate microfluidic networks. Also, the actual enhancement of the performance of the electrochemical microreactor, i.e. chemical conversion efficiency, using multiple inlets, multiple outlets, or herringbone ridges is reported.     

Reversible Transformation between Cubane and Stairstep Cu4I4 Clusters Using Heat or Solvent Vapor

The controlled self‐assembly of CuI and an asymmetric ligand with mixed N/S donors, 2‐(tert‐butylthio)‐N‐(pyridin‐3‐yl)acetamide ( L ), afforded three Cu^I coordination polymers (CPs), [Cu₄I₄ L ₂(MeCN)₂]_n ( 1 ), [Cu₄I₄ L ₂]_n ( 2 ), and {[Cu₄I₄ L ₂] ? MeOH}_n ( 3 ). X‐ray analyses showed that CPs 1 – 3 are supramolecular isomers with 1, 2, and 3D structures, respectively. CP 1 adopts a stairstep Cu₄I₄ cluster, whereas CPs 2 and 3 are composed of cubane‐like Cu₄I₄ clusters. Crystal‐to‐crystal transformations of 1 to 2 and 3 showed reversible transformations between different Cu₄I₄ clusters using heat or solvent (acetonitrile or methanol) vapor. CP 2 was reversibly transformed to 3 by the addition of methanol and heat. Therefore, the transformations between supramolecular isomers 1 , 2 , and 3 are completely reversible.     

Evaluation of bias voltage effect on diamond‐like carbon coating properties deposited on tungsten carbide cobalt

Diamond‐like carbon (DLC) coatings are getting new trends for cutting tool applications. In this research work, the DLC coatings were deposited on 15 × 15 × 5‐mm tungsten carbide cobalt substrates with variation of bias voltage from 0 to 500 V. The DLC films of 400 nm were deposited using filter cathode vacuum arc system, and 100‐nm chromium interlayer was deposited by sputtering. The optimized conditions for plasma pretreatment at different argon flow rates and deposition rates with bias variation were found. The effect of bias voltage on microstructure, tribology, adhesion, and mechanical properties were evaluated. The characterization techniques employed were field emission electron microscopy, Raman spectroscopy, wear test, SEM, scratch test, and nano‐indentation. The effect of substrate pretreatment on film adhesion was also evaluated. It was observed that etching rate increased with the increase in Ar flow rate while DLC deposition and sputtering rates decreased with increase in the bias voltage. The characterization suggests the DLC coatings deposited at 0 V bias as optimum condition because of showing the best results among all other conditions. Copyright © 2014 John Wiley & Sons, Ltd.     

Coptis chinensis Franch Directly Inhibits Proteolytic Activation of Kallikrein 5 and Cathelicidin Associated with Rosacea in Epidermal Keratinocytes

Rosacea is a common and chronic inflammatory skin disease that is characterized by dysfunction of the immune and vascular system. The excessive production and activation of kallikerin 5 (KLK5) and cathelicidin have been implicated in the pathogenesis of rosacea. Coptis chinensis Franch (CC) has been used as a medicinal herb in traditional oriental medicine. However, little is known about the efficacy and mechanism of action of CC in rosacea. In this study, we evaluate the effect of CC and its molecular mechanism on rosacea in human epidermal keratinocytes. CC has the capacity to downregulate the expression of KLK5 and cathelicidin, and also inhibits KLK5 protease activity, which leads to reduced processing of inactive cathelicidin into active LL-37. It was determined that CC ameliorates the expression of pro-inflammatory cytokines through the inhibition of LL-37 processing. In addition, it was confirmed that chitin, an exoskeleton of Demodex mites, mediates an immune response through TLR2 activation, and CC inhibits TLR2 expression and downstream signal transduction. Furthermore, CC was shown to inhibit the proliferation of human microvascular endothelial cells induced by LL-37, the cause of erythematous rosacea. These results demonstrate that CC improved rosacea by regulating the immune response and angiogenesis, and revealed its mechanism of action, indicating that CC may be a useful therapeutic agent for rosacea.     

CoMnO2-Decorated Polyimide-Based Carbon Fiber Electrodes for Wire-Type Asymmetric Supercapacitor Applications

In this work, we report the carbon fiber-based wire-type asymmetric supercapacitors (ASCs). The highly conductive carbon fibers were prepared by the carbonized and graphitized process using the polyimide (PI) as a carbon fiber precursor. To assemble the ASC device, the CoMnO₂-coated and Fe₂O₃-coated carbon fibers were used as the cathode and the anode materials, respectively. Herein, the nanostructured CoMnO₂ were directly deposited onto carbon fibers by a chemical oxidation route without high temperature treatment in presence of ammonium persulfate (APS) as an oxidizing agent. FE-SEM analysis confirmed that the CoMnO₂-coated carbon fiber electrode exhibited the porous hierarchical interconnected nanosheet structures, depending on the added amount of APS, and Fe₂O₃-coated carbon fiber electrode showed a uniform distribution of porous Fe₂O₃ nanorods over the surface of carbon fibers. The electrochemical properties of the CoMnO₂-coated carbon fiber with the concentration of 6 mmol APS presented the enhanced electrochemical activity, probably due to its porous morphologies and good conductivity. Further, to reduce the interfacial contact resistance as well as improve the adhesion between transition metal nanostructures and carbon fibers, the carbon fibers were pre-coated with the Ni layer as a seed layer using an electrochemical deposition method. The fabricated ASC device delivered a specific capacitance of 221 F g⁻¹ at 0.7 A g⁻¹ and good rate capability of 34.8% at 4.9 A g⁻¹. Moreover, the wire-type device displayed the superior energy density of 60.2 Wh kg⁻¹ at a power density of 490 W kg⁻¹ and excellent capacitance retention of 95% up to 3000 charge/discharge cycles.     

All-solid-state carbonate-selective electrode based on a molecular tweezer-type neutral carrier with solvent-soluble conducting polymer solid contact

Carbonate-selective membranes were prepared by incorporating a molecular tweezer-type carbonate-selective neutral carrier [N,N-dioctyl-3alpha,12alpha-bis(4-trifluoroacetylbenzyloxy)-5beta-cholan-24-amide] into a room temperature vulcanizing-type silicone rubber (3140 RTV-SR) matrix, and deposited on the planar-type electrodes (Pt containing Ag/AgCl electrodes formed on a ceramic plate) with and without an intermediary conducting polymer layer. Two types of solvent-soluble conducting polymers [poly(1-hexyl-3,4-dimethyl-2,5-pyrrolylene) or poly(3-octylthiophene-2,5-diyl)] have been examined as the solid contact material. Potentiometric properties of the resultant all-solid-state electrodes were evaluated in terms of their carbonate selectivity, response slope, potential stability and reproducibility. The sensitivity and carbonate selectivity of the SR membrane-based all-solid-state electrodes with conducting polymer solid contact were comparable to those of conventional electrodes. Experimental results also showed that the intermediary conducting polymer layer used in the all-solid-state electrodes greatly reduces the interference from dissolved oxygen.     

Upregulation of extracellular matrix metalloproteinase inducer (EMMPRIN) and gelatinases in human atherosclerosis infected with Chlamydia pneumoniae: the potential role of Chlamydia pneumoniae infection in the progression of atherosclerosis

Chlamydia pneumoniae infection implicated as an important etiologic factor of atherosclerosis, especially in coronary artery disease (CAD), was found in vitro to be associated with the induction of matrix metalloproteinases (MMPs). An extracellular matrix metalloproteinase inducer (EMMPRIN)/ membrane-type 1 matrix metalloproteinase (MT1-MMP) system which induces and activates MMPs, is suggested to be functional and were upregulated in the failing myocardium. However, the upstream regulation of MMPs by C. pneumoniae within atheroma itself remains unclear. We evaluated the seroepidemiologic study of C. pneumoniae infection in CAD patients (n= 391) and controls (n=97) and performed histopathological and in vitro analysis in atherosclerotic vascular tissues obtained from patients with seropositive to C. pneumoniae (n=20), by using immunochemistry for C. pneumoniae, EMMPRIN/MT1-MMP, MMP-2, and MMP-9. The seropositive rates of both anti-C. pneumoniae IgG and IgA were 56.7% in CAD group and 43.3% in control group (P=0.033). Seropositive rate was increased in subgroups of CAD patients without conventional coronary risk factors compared to those with conventional risk factors. Immunoreactivities of EMMPRIN, MT1-MMP, MMP-2, and MMP-9 were increased in the atheromatous plaque itself, predominantly in immunoreactive macrophages/mononuclear cells to C. pneumoniae. Furthermore, Western blot analysis showed that EMMPRIN and MMP-2 were detected more prominently in atherosclerotic tissues infected with C. pneumoniae compared to control tissues. Zymographic analysis revealed that activities of MMP-2 and MMP-9 were more increased in atherosclerotic tissues infected with C. pneumoniae compared to control tissues. The present study demonstrated upstream regulation of MMPs can be induced by C. pneumoniae within atheromatous plaque itself. These findings help to understand the potential role of C. pneumoniae in the progression of atherosclerosis.     

Ruthenium-catalyzed reductive cyclization of nitroarenes with trialkylamines leading to quinolines

Nitroarenes react with trialkylamines in the presence of a catalytic amount of a ruthenium catalyst together with tin(II) chloride dihydrate at 180 °C in an aqueous medium (toluene–H₂O) to afford the corresponding quinolines in moderate to good yields. The catalytic pathway seems to be proceeded via a sequence involving initial reduction of nitroarenes to anilines, alkyl group transfer from alkylamines to anilines to form an imine, dimerization of imine, and heterocyclization.     

Reaction of phosgene with the tricycle related to the minor base of phenylalanine transfer ribonucleic acids

1-Benzylwye (8) underwent electrophilic substitution at the 7-position in the presence of phosgene and pyridine in tetrahydrofuran (THF) to afford the 1,4-dihydropyridines (11, 10, and 14) together with the carboxylic acid 6 and its methyl ester 2 after short treatment of the reaction mixture with methanol and then with water. When triethylamine was used instead of pyridine, phosgene reacted with triethylamine rather than 8, producing (E)-3-(diethylamino)propenoyl chloride (17) and diethylcarbamoyl chloride (18).     

Copolymerization of ethylene and 1-butene with highly active Ticl4/THF/Mgcl2, Ticl4/THF/Mgcl2/SiO2, and TiCl3.1/3AlCl3 catalysts

Highly active catalysts for copolymerization have been prepared by the precipitation of MgCl₂/ToCl₄ complex with or without high surface area silica. Copolymerization of ethylene and 1-butene has been tested by using the prepared catalysts at various concentrations of 1-butene. The catalytic activities are 20–80 kg/g Ti h. The rate of copolymerization is strongly affected by the addition of 1-butene. The decay rate of copolymerization is first order with respect to time. Analyses of copolymers with solvent extraction, DSC, IR, XRD, and NMR were performed. Ethylene reactivity ratio (k₁₁) for TiCl₄/MgCl₂/THF catalyst is calculated to be about 26 by NMR spectrum. © 1994 John Wiley & Sons, Inc.