Silylated Tag-Assisted Peptide Synthesis: Continuous One-Pot Elongation for the Production of Difficult Peptides under Environmentally Friendly Conditions

Addition of the silylated tag (STag) enables peptides to be highly soluble in CPME, allowing them to be used at high concentrations in a coupling reaction to enhance reactivity and achieve effective synthesis of sterically hindered peptides. We described the development of a continuous one-pot STag-assisted peptide synthesis platform as a method that provides near-stoichiometric, speedy, environmentally friendly, and scalable peptide synthesis.     

Binary amorphous solids consisting of 2,4,6-triarylphenoxyl radicals and their dimers

Although molecular amorphous materials represent an important area of research in solid-state chemistry, studies pertaining to these systems have been restricted almost exclusively to amorphous solids based on a single molecule. In this study, we found that, while the 2,4,6-bis(4-tert-butylphenyl)phenoxyl radical (2_M) and its dimer (2_D) did not give single-component amorphous solids, they rapidly formed the corresponding binary amorphous solid IIa following their condensation from benzene, dichloromethane, chloroform, and ethyl acetate solutions. The formation of IIa could be attributed to the good solubilities of 2_M and 2_D in these solvents and the high packing efficiencies of these amorphous solids. IIa was also obtained when crystals of 2_D (IIb) were ground together. The solid-state formation of IIa would not only involve the locational exchange of 2_M and 2_D, but would also involve chemical exchanges.     

Effect of laser-focusing conditions on propagation and monoenergetic electron production in laser-wakefield accelerators

The effect of laser-focusing conditions on the evolution of relativistic plasma waves in laser-wakefield accelerators is studied both experimentally and with particle-in-cell simulations. For short focal-length (w_{0}lambda_{p}), a single optical filament can capture the majority of the laser energy and self-guide over distances comparable to the dephasing length, even for these short pulses (ctau approximately lambda_{p}). This allows the wakefield to evolve to the correct shape for the production of the monoenergetic electron bunches, as measured in the experiment.     

Low-group-velocity and low-dispersion slow light in photonic crystal waveguides

Photonic crystal slab line defect waveguides with slightly small innermost holes are theoretically expected to show light transmission with low-group-velocity and low-dispersion (LVLD) characteristics owing to a linear and almost flat photonic band. In this study, the LVLD characteristics of such waveguides were experimentally confirmed by using modulation phase shift measurement and transmission of ultrashort optical pulses. These results will be applicable to buffering and nonlinearity enhancement of optical signals.     

Synthesis and characterization of pi-extended bowl-shaped pi-conjugated molecules

A series of pi-extended bowl-shaped pi-conjugated compounds were synthesized from sumanene and characterized, and among them the terthiophene derivative showed a remarkable red-shifted absorption and small band gap, which wa rationalized by molecular orbital calculation.     

Fine tuning of the orifice size of an open-cage fullerene by placing selenium in the rim: insertion/release of molecular hydrogen

A newly synthesized open-cage fullerene containing selenium in the rim of the 13-membered-ring orifice allows milder conditions for hydrogen insertion, and the rate for hydrogen release is ca. three times faster than its sulfur analogue.     

The drug release profile from calcium-induced alginate gel beads coated with an alginate hydrolysate

Calcium-induced alginate gel bead (Alg-Ca) coated with an alginate hydrolysate (Alg), e.g. the guluronic acid block (GB) was prepared and the model drug, hydrocortisone release profiles were investigated under simulated gastrointestinal conditions. Their molecular weights were one sixth or one tenth that of Alg and the diffraction patterns of the hydrolysates resembled that of Alg. The drug release rate from Alg-Ca coated with GB apparently lowered than that of Alg-Ca (coating-free) in the gastric juice (pH1.2). And the coating did not resist the disintegration of Alg-Ca in the intestinal juice (pH 6.8) and the gel erosion accelerated the drug release. On the other hand, for the coated Alg-Ca containing chitosan, the drug release showed zero-order kinetics without rapid erosion of Alg-Ca. The drug release rate from Alg-Ca was able to be controlled by the coating and modifying the composition of the gel matrix.     

Electrochemical detection of E. coli 16S rDNA sequence using air-plasma-activated fullerene-impregnated screen printed electrodes

A new DNA modified electrode for the electrochemical detection of 16S rDNA extracted from Escherichia coli (JCM1649) is proposed. The electrodes were fabricated by screen printing a fullerene-impregnated carbon ink onto a poly(methylmethacrylate) substrate and immobilizing a probe DNA on the surface after activating the electrode with air plasma. The results indicated a dramatic improvement in the surface coverage of the immobilized probe DNA, and of the reduction peak of the redox indicator (Co(phen)(3)(3+)) due to the incorporation of fullerene. By immobilizing the probe onto the fullerene-impregnated screen-printed electrodes, the PCR product of the 16S rDNA extracted from E. coli was directly detected without any pretreatment. A well defined signal difference was observed between the perfectly matching oligonucleotide and the mismatching one, and it was possible to detect the target at the modified electrode. This method enabled us to clearly detect the two base mismatches in the ca. 1500-bases long 16S rDNA sequence.