Robust monolithic silica-based on-chip electro-osmotic micro-pump

A robust, compact, on-chip, electro-osmotic micro-pump (EOP) for micro-flow analysis, based on parallel, encased, 10 x 0.1 mm I.D. monolithic silica capillary columns has been developed. A 15 x 40 x 2 mm poly(methyl methacrylate) (PMMA) chip, containing a total of nine parallel EOP systems was fabricated, allowing the use of single, double or triple monolithic columns to produce increased flow as required. The monolithic silica was compatible with both aqueous and organic solvents without swelling or shrinking problems, with the triple column EOP capable of generating flow of up to 0.6 microL min(-1) under zero pressure load and over 0.1 microL min(-1) with an applied pressure of ca. 2.4 bar using an applied voltage of just 2 kV. Current generated at the 2 kV applied voltage for a 2 mM acetate buffer solution (pH 4.5) was under 4 microA, allowing stable, bubble-free flow. The developed triple column EOP was incorporated within a micro-fluidic chip (5.0 x 2.0 x 0.4 cm) integrated with a second single 10 x 0.1 mm column EOP, for combined sample injection and simple on-chip micro-flow analysis.     

Determination of ketotifen by using calcein as chemiluminescence reagent

Chemiluminescence (CL) was observed when potassium hexacyanoferrate(III) reacted with the mixture of calcein and ketotifen. Interestingly, the CL intensity would be enhanced by trace amounts of Mg²⁺ and the CL intensity was strongly dependent on ketotifen concentration. Based on this phenomenon, a flow injection CL method was established for the determination of ketotifen. The possible CL mechanism is proposed based on the kinetic characteristic of the CL reaction, CL spectrum, ultraviolet (UV) spectra and fluorescent spectra. The CL intensity was correlated linearly with concentration of ketotifen over the range of 6.0 × 10⁻⁹ to 2.0 × 10⁻⁷ g mL⁻¹ and the detection limit was 3 × 10⁻⁹ g mL⁻¹. The relative standard deviation was 1.8% for 2.0 × 10⁻⁸ g mL⁻¹ ketotifen (n = 11). This method was applied to the determination of ketotifen in the tablets successfully.     

Interface hydrogen-bonded core-shell nanofibers by coaxial electrospinning

Core-shell nanofibers were prepared by coaxial electrospinning technology,with poly(ethylene oxide) (PEO) as the core while poly(acrylic acid) (PAA) as the shell.PEO and PAA can form polymer complexes based on hydrogen bonding.In order to avoid forming strong hydrogen bonding complexes at nozzle and blocking spinning process,a polar aprotic solvent,N,N-dimethylformamide (DMF),was selected to dissolve PEO and PAA respectively.SEM,TEM and DSC were utilized to characterize the morphology and structure of PEO-PAA core-shell nanofibers.FTIR spectra demonstrated that hydrogen bonding was formed at the core-shell interface.In addition,the PAA shell of the nanofibers can be cross-linked by ethylene glycol (EG) under heat treatment,which increases the stability and extends the potential applications in aqueous environment.     

A selective and cost-effective method for the reductive deuteration of activated alkenes

A new single electron transfer reaction for the reductive deuteration of activated alkenes has been developed for the selective synthesis of α,β-dideuterio compounds. A cheap, stable and commercially-available sodium dispersion with high specific surface area is employed as the electron donor to replace the traditionally used sodium/liquid ammonium system. Deuterium source is provided by EtOD-d₁. Excellent yields and deuterium incorporations were obtained across a broad range of activated alkenes with good functional group tolerance. This method provided a cheap, efficient and operationally-simple method for the synthesis of deuterium labeled compounds.     

Heavy neutral MSSM Higgs bosons at the photon linear collider — a comparison of two analyses

Measurement of the heavy neutral MSSM Higgs bosons H and A production in the process γγ → A/H → b at the Photon Linear Collider [1,2] has been considered in two independent analyses for the parameter range corresponding to the so-called ‘LHC wedge’. Significantly different conclusions were obtained; signal-to-background ratio 36 vs. 2. Here assumptions and results of these two analyses are compared. We have found that differences in the final results are mainly due to different assumptions on γγ-luminosity spectra, jet definitions and selection cuts.      

Evidence for visible quantum cutting via energy transfer in SrAl12O19:Pr,Cr

Evidence for visible quantum cutting involving the emission of two visible photons for each vacuum-ultraviolet (VUV) photon absorbed is demonstrated in SrAl(12)O(19):Pr,Cr using synchrotron radiation as one of the excitation sources. Upon VUV excitation of the 4f5d states of Pr(3+), quantum cutting could occur by a two-step energy transfer from Pr(3+) to Cr(3+) by cross relaxation and sequential transfer of the remaining excitation energy. A theoretical visible quantum efficiency of 147% is estimated in SrAl(12)O(19):2% Pr,5% Cr, suggesting the possibility of a VUV phosphor with visible quantum efficiency higher than 100% based on Pr(3+)-Cr(3+) pair in oxide materials.     

Lipase-catalyzed synthesis of novel galactosylated cholesterol

In an organic phase system,an enzymes lipase was used as a catalyst to synthesize galactosylated cholesterol,(5-cholesten-3b-yl)[(4-O-β-D-galactopyranosyl)D-glucitol-6]sebacate(CHS-SE-LA),which contains galactose residues.Its chemical structure was characterized by ESI-MS,and NMR.For HepG2 cells,the cellular fluorescence intensities of liposomes modified with CHS-SE-LA(GAL-FL) were as much as 2.6-fold(p 0.01) control liposomes(FL).Moreover,the presence of excess galactose significantly inhibited the uptake of GAL-FL suggesting ASGPR mediated uptake.In conclusion,the novel galactosylated ligand CHS-SE-LA was synthesized by lipase-catalyzation and revealed a great potential as drug carrier materials for hepatocyte-selective targeting.     

A Non‐Enzymatic Glucose Sensor Based on Ni/MnO2 Nanocomposite Modified Glassy Carbon Electrode

A novel flower like 3D nickel/manganese dioxide (Ni/MnO₂) nanocomposite was synthesized by a kind of simple electrochemical method and the formation mechanism of flower like structure was also researched. In addition, morphology and composition of the nanocomposite were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), and X‐ray photoelectron spectroscopy (XPS). Then the Ni/MnO₂ nanocomposites were applied to fabricate electrochemical non‐enzymatic glucose sensor. The electrochemical investigation for the sensor indicated that it possessed an excellent electrocatalytic property for glucose, and could applied to the quantification of glucose with a linear range from 2.5×10^?7 to 3.5×10^?3 M, a sensitivity of 1.04 mA mM^?1 cm^?2, and a detection limit of 1×10^?7 M (S/N=3). The proposed sensor also presented attractive features such as interference‐free, and long‐term stability. The present study provided a general platform for the one‐step synthesis of nanomaterials with novel structure and can be extended to other optical, electronic and magnetic nanocompounds.     

Porous Liquids: A Promising Class of Media for Gas Separation

A porous liquid containing empty cavities has been successfully fabricated by surface engineering of hollow structures with suitable corona and canopy species. By taking advantage of the liquid‐like polymeric matrices as a separation medium and the empty cavities as gas transport pathway, this unique porous liquid can function as a promising candidate for gas separation. Moreover, such a facile synthetic strategy can be further extended to the fabrication of other types of nanostructure‐based porous liquid, opening up new opportunities for preparation of porous liquids with attractive properties for specific tasks.     

Highly Enantioselective Nickel‐Catalyzed Intramolecular Reductive Cyclization of Alkynones

The first asymmetric nickel‐catalyzed intramolecular reductive cyclization of alkynones is reported. A P‐chiral monophosphine and triethylsilane were used as the ligand and the reducing reagent, respectively, to form a series of tertiary allylic alcohols bearing furan/pyran rings in excellent yields and enantioselectivities. This reaction has a broad substrate scope and enabled the efficient synthesis of dehydroxycubebin and chiral dibenzocyclooctadiene skeletons.