Enantio‐ and Diastereoselective Total Synthesis of (+)‐Panepophenanthrin,a Ubiquitin‐Activating Enzyme Inhibitor,and Biological Properties of Its New Derivatives

The asymmetric total synthesis of (+)‐panepophenanthrin, an inhibitor of ubiquitin‐activating enzyme (E1), has been accomplished using catalytic asymmetric α aminoxylation of 1,4‐cyclohexanedione monoethylene ketal as a key step, followed by several diastereoselective reactions. The biomimetic Diels–Alder reaction of a monomer precursor was found to proceed efficiently in water. The investigation of the biological properties of new derivatives of (+)‐panepophenanthrin enabled us to develop new cell‐permeable E1 inhibitors, RKTS‐80, ‐81, and ‐82.     

High-performance electric double-layer capacitors using mass-produced multi-walled carbon nanotubes

Mass-produced multi-walled carbon nanotubes (MWNTs, which have the trademark VGNF®) have been investigated for their potential for use in electric double-layer capacitors (EDLCs). The variation aspects of these MWNTs by KOH activation showed quite interesting features. The gravimetric capacitance enhancement and specific surface area on KOH activation increased linearly. However, the capacitance per unit surface area has a maximum at 200 wt.?% of KOH addition. The VGNF-KOH 500 sample exhibits a capacitance enhancement as much as 13 times greater (28.3 F/g) than that of the as-grown materials (2.2 F/g), under the conditions of charging up to 3.5 V and discharging at a current density of 10 mA/cm². Interestingly, for this MWNT (VGNF®), selective attack on its amorphous carbon impurity has also been observed, as demonstrated from both scanning electron microscopy observations and Raman spectra. Consequently, the results of this study will provide insight into the potentiality of using MWNTs for EDLC electrodes, which would enable the cheapest production cost among the various types of carbon nanotubes.     

Simple and controlled fabrication of nanoscale gaps using double-angle evaporation

A simple and controlled method for fabricating nanometer-spaced electrodes is presented. This method uses electron-beam lithography followed by double-angle evaporation of thin metallic films. By simply changing the film thickness, one can adjust the separation of the electrodes. In this method, error is caused mainly by the granularity of the deposited metals. We have observed the Coulomb blockade effect of 20 nm Au colloidal particles captured in a gap fabricated using this method.     

An Amphiphilic Selenide Catalyst Behaves Like a Hybrid Mimic of Protein Disulfide Isomerase and Glutathione Peroxidase 7

Protein disulfide isomerase (PDI) and glutathione peroxidase 7 (GPx7) cooperatively promote the oxidative folding of disulfide (SS)‐containing proteins in endoplasmic reticulum by recognizing the nascent proteins to convert them into the native folds by means of SS formation and SS isomerization and by catalyzing reoxidation of reduced PDI with H₂O₂, respectively. In this study, new amphiphilic selenides with a long‐chain alkyl group were designed as hybrid mimics of PDI and GPx7 and were applied to the refolding of reduced hen egg‐white lysozyme (HEL‐R). Competitive SS formation at pH 4 using HEL‐R and glutathione (GSH) in the presence of the selenide catalyst and H₂O₂ showed that the amphiphilic selenides can preferentially catalyze SS formation of HEL‐R, probably on account of hydrophobic interactions between the protein and the catalyst. In contrast, simple water‐soluble selenides did not exhibit such behavior. In addition, when the pH of the solution was adjusted to 8.5 after the SS formation, surviving GSH promoted the SS isomerization of misfolded HEL to recover the native SS linkages. Thus, the amphiphilic selenides designed here could mimic the function of the PDI‐GPx7 system. The combination of a water‐soluble selenide and a long‐chain alkyl group would be a useful motif in designing medicines for both protein misfolding diseases and antioxidant therapy.     

Synthesis of Diverse Aromatic Ketones through C−F Cleavage of Trifluoromethyl Group

An efficient synthetic method of aromatic ketones through C−F cleavage of trifluoromethyl group is disclosed. The high functional group tolerance of the transformation and the remarkable stability of trifluoromethyl group in various reactions enabled multi-substituted aromatic ketone synthesis in an efficient route involving useful transformations such as ortho-lithiation, aryne chemistry, and cross-couplings.     

Chiral SU(3) dynamics and the quasibound K – pp cluster

The prototype of a $\bar{K}$ nuclear cluster, K ^???pp, has been investigated using effective $\bar{K}N$ potentials based on chiral SU(3) dynamics. Variational calculation shows a bound state solution with shallow binding energy B(K ^???pp)?=?20±3 MeV and broad mesonic decay width $\Gamma(\bar{K}NN \rightarrow \pi Y N)=40$ –70 MeV. The $\bar{K}N(I=0)$ pair in the K ^???pp system exhibits a similar structure as the Λ(1405). We have also estimated the dispersive correction, p-wave $\bar{K}N$ interaction, and two-nucleon absorption width.     

Effects of excess oxygen content on the hole-carrying CuO2-layers in Tl2(Ba1−xSrx)2Ca2Cu3Oy superconducting oxides

The effects of oxygen doping on the hole-carrying CuO₂-layers in Tl₂(Ba_1−xSr_x)₂Ca₂Cu₃O_y were studied by combined chemical and valence analysis, T_c measurements and neutron diffraction. The highest T_c is characterized by an optimal excess oxygen content, Δy, dichotomizing the under- and over-doped regions for each Sr concentration. While the average Tl valence is close to 3.0 and independent of Δy, the average Cu valence shows a linear dependence with Δy. An increase of the flatness of the CuO₂ plane, characterized by the O(2)-Cu(2)-O(2) bond angle of ∼176°, was observed at the optimal Δy.