Green,Multi‐Gram One‐Step Synthesis of Core–Shell Nanocomposites in Water and Their Catalytic Application to Chemoselective Hydrogenations

We devise a new and green route for the multi‐gram synthesis of core–shell nanoparticles (NPs) in one step under organic‐free and pH‐neutral conditions. Simply mixing core and shell metal precursors in the presence of solid metal oxides in water allowed for the facile fabrication of small CeO₂‐covered Au and Ag nanoparticles dispersed on metal oxides in one step. The CeO₂‐covered Au nanoparticles acted as a highly efficient and reusable catalyst for a series of chemoselective hydrogenations, while retaining C=C bonds in diverse substrates. Consequently, higher environmental compatibility and more efficient energy savings were achieved across the entire process, including catalyst preparation, reaction, separation, and reuse.     

Performance Characteristics of Power Build-Up Cavity for Raman Spectroscopic Measurement

Performance characteristics of power build-up cavity (PBC) as the light source of a Raman spectroscopy based gas sensor were studied. The key parameter to optimize stable and high intra-cavity power operation was beam diameter of the back reflected beam from external cavity to diode laser. The optimum diameter determined by an appropriate distance between the cavity and diode laser was found to be comparable with the waveguide cross section of diode laser for the effective spatial filtering, where inevitable cavity coupling loss caused by slight spatial mode mismatching existed. A PBC with a finesse of ∼10300 achieved a stable TEM₀₀ mode in excess of intra-cavity power of 80 watts pumped by a 10 milliwatts diode laser. Simultaneously, the PBC wavelength is found to be passively locked effectively at 670 +/− 0.15 nm where the center of the gain region exists. A Raman spectrum of nitrogen measurement was demonstrated.     

Differential-pulse anodic stripping voltammetry of copper with a chemically-modified glassy carbon electrode

Copper at the low or fractional ng g^?1 level in 0.1 M oxalic acid solutions at pH 1.6 is electrodeposited on a chemically-modified glassy carbon electrode with surface-bound

groups at ?0.6 V vs. Ag/AgCl (3.3 M KCl). The deposit is then anodically stripped in the same solution, a current-potential curve being recorded by the differential-pulse technique. The advantages of this electrode over an unmodified glassy carbon electrode include higher sensitivity, precision and selectivity; the modified electrode can be used 50–100 times without further treatment.     

Reusable montmorillonite-entrapped organocatalyst for asymmetric Diels-Alder reaction

A chiral organocatalyst was successfully entrapped by montmorillonite clay using the cation-exchange method. The mont-entrapped organocatalyst acted as a highly efficient and reusable heterogeneous catalyst for the asymmetric Diels-Alder reaction, without loss of its initial activity.