Nonaqueous nanoscale metal transfer by controlling the stickiness of organic film

Nanoscale metal patterns were successfully reproduced on top of a functional organic layer by a direct metal-transfer technique (DMT). A gold film deposited on the protruding features of a stamp was transferred to the organic layer by controlling its stickiness through a two-step thermal treatment. The process was also suitable for the transfer of highly adhesive metal materials to the stamp surface by using an additional gold layer. Chromium nanowires at 70 nm half-pitch were faithfully produced without any damage to the organic active layer.     

Structure-antimicrobial activity relationship between pleurocidin and its enantiomer

To develop novel antibiotic peptides useful as therapeutic drugs, the enantiomeric analogue of pleurocidin (Ple), which is a well known 25-mer antimicrobial peptide, was designed for proteolytic resistance by D-amino acids substitution. The proteolytic resistance was confirmed by using HPLC after the digestion with various proteases. To investigate the antibiotic effect of L- and D-Ple, the antibacterial activity and hemolytic effect were tested against human erythrocytes. The D-Ple showed a decreased antibacterial activity and a dramatically decreased hemolytic activity compared with L-Ple. The hemolytic effect of analogue was further confirmed by using calcein leakage measurement with liposome. To elucidate these results, the secondary structure of the peptides was investigated by using circular dichroism spectroscopy. The results revealed that D-Ple, as well as L-Ple, had typical alpha-helical structures which were mirror images, with a different helicity. These results suggested that the discrepancy of the structure between the two peptides made their antibacterial activity distinct.     

Preparation of poly(vinylidene fluoride) nanocomposite membranes based on graft polymerization and sol–gel process for polymer electrolyte membrane fuel cells

Proton conducting nanocomposite membranes consisting of poly(vinylidene fluoride-co-chlorotrifluoroethylene)-graft-poly(styrene sulfonic acid), i.e., P(VDF-co-CTFE)-g-PSSA graft copolymer and sulfonated silica and were prepared using a sol–gel reaction and subsequent oxidation of a silica precursor, i.e., (3-mercaptopropyl) trimethoxysilane (MPTMS). The successful formation of amorphous phase nanocomposite membranes was confirmed via FT-IR and wide-angle X-ray scattering. All membranes were semi-transparent and mechanically strong, as characterized by a universal tensile machine. Transmission electron microscopy and small-angle X-ray scattering analysis revealed that silica 5–10 nm in size were homogeneously dispersed in the matrix at up to 5 wt.% of MPTMS. At higher concentrations, the silica grew to more than 50 nm in size, which disrupted the microphase-separated structure of the graft copolymer. As a result, both proton conductivity (0.12 S/cm at 25 °C) and single cell performance (1.0 W/cm² at 75 °C) were maximal at 5 wt.% MPTMS.     

A facile approach for the delivery of inorganic nanoparticles into the brain by passing through the blood-brain barrier (BBB)

This study provides an easy and simple method to obtain inorganic nanoparticles that can penetrate the blood-brain barrier, the heavily guarded system in the brain, via cross-linked serum albumin surface coatings. Their intact BBB permeability was confirmed in both in vitro and in vivo tests.     

Sesquiterpenoids and 2‐(2‐Phenylethyl)‐4H‐chromen‐4‐one (=2‐(2‐Phenylethyl)‐4H‐1‐benzopyran‐4‐one) Derivatives from Aquilaria malaccensis Agarwood

The four new sesquiterpenoids 1 – 4 , and the new 2‐(2‐phenylethyl)‐4H‐chromen‐4‐one (=2‐(2‐phenylethyl)‐4H‐1‐benzopyran‐4‐one) derivative 5 , together with the two known sesquiterpenoids 6 and 7 , the five known chromenones 8 – 12 , and 1‐hydroxy‐1,5‐diphenylpentan‐3‐one ( 13 ), were isolated from a 70% MeOH extract of Aquilaria malaccensis agarwood chips. Their structures were elucidated on the basis of comprehensive spectral analyses and comparison with literature data.     

Acoustic streaming in lithotripsy fields: preliminary observation using a particle image velocimetry method

This study considers the acoustic streaming in water produced by a lithotripsy pulse. Particle image velocimetry (PIV) method was employed to visualize the acoustic streaming produced by an electromagnetic shock wave generator using video images of the light scattering particles suspended in water. Visualized streaming features including several local peaks and vortexes around or at the beam focus were easily seen with naked eyes over all settings of the lithotripter from 10 to 18 kV. Magnitudes of the peak streaming velocity measured vary in the range of 10-40 mm s(-1) with charging voltage settings. Since the streaming velocity was estimated on the basis of a series of the video images of particles averaged over 1/60s, the time resolution limited by the video frame rate which is 1-2 orders of magnitude larger than driving acoustic activities, measured velocities are expected to be underestimated and were shown a similar order of magnitude lower than those calculated from a simple theoretical consideration. Despite such an underestimation, it was shown that, as predicted by theory, the magnitude of the streaming velocity measured by the present PIV method was proportional to acoustic intensity. In particular it has almost a linear correlation with peak negative pressures (r=0.98683, p=0.0018).     

Bis(hydroxyamino)triazines: versatile and high-affinity tridentate hydroxylamine ligands for selective iron(III) chelation

A new versatile family of chelating agents based on bis(hydroxyamino)-1,3,5-triazines, BHTs, is described. The properties of different BHT ligands are determined by electrochemistry, spectroscopy and titrimetry revealing high redox stability, transparency in the visible range, and diprotic acid-like behaviour in the 5-9 pH range. The iron(III) and iron(II)-BHT complexes were studied revealing high affinity of BHTs to iron(III). Electrochemical studies show exceptional preference of the BHT ligands to iron(III) over iron(II), this, in addition to their small size and their fast and reversible electrochemistry makes them potentially useful electrochemical redox couples for the low end of the aqueous potential window (<0.6 V, vs. NHE). The synthetic versatility of the new ligands allows easy tuning of the hydrophobicity, redox potential, and to some extent the stability constant of the complexes by alteration of the peripheral groups appended to the BHTs.     

Sorption of uranium using silica gel with benzoylthiourea derivatives

Benzoylthiourea derivatives (N,N-diphenyl-N′-(3-methylbenzoyl)thiourea and diphenyl-N′-(4-methylbenzoyl)thiourea) were impregnated onto silica gel. The preconcentration of uranium(VI) from aqueous solution was investigated. Extraction conditions were optimized in batch method prior to determination by uv–visible absorption spectrometry using arsenazo(III). The optimum pH for quantitative adsorption was found as 3–7. Quantitative recovery of uranium (VI) was achieved by stripping with 0.1 mol L^?1 HCl. Equilibration time was determined as 30 min for 99% sorption of U(VI). Under optimal conditions, dynamic linear range of for U(VI) was found as 0.25–10 μg mL^?1. The relative standard deviation as percentage and detection limit were 5.0% (n = 10) for 10 μg mL^?1 U(VI) solution and 8.7 ng mL^?1, respectively. The method was employed to the preconcentration of U(VI) ions in soil and tap water samples.     

Structural characteristics of mixed oxides MOx/SiO2 affecting photocatalytic decomposition of methylene blue

A series of photocatalysts based on silica (nanoparticulate) supported titania, ceria, and ceria/zirconia were synthesized and characterized by a variety of techniques including surface area measurements, X-ray diffraction, Fourier transform infrared spectroscopy, zeta potential, surface charge density, and photocatalytic behavior toward methylene blue decomposition. Thermal treatment at 600 °C increases the anatase content of the titania based catalysts detected by XRD. Changes in the infrared spectra before and after thermal treatment indicate that at low temperature there are more SiOTi bonds than at high temperature. As these bonds break upon heating the SiO₂ and TiO₂ separate, allowing the TiO₂ anatase phase to form. This results in an increased catalytic activity for the thermally treated samples. Nearly all titania based samples exhibit a negative surface charge density at pH 7 (initial pH of photocatalytic studies) which aids adsorption of methylene blue. The crystallinity of ceria and ceria/zirconia based catalysts are in some cases limited, and in others non-existent. Even though the energy band gap (E_g) can be lower for these catalysts than for the titania based catalysts, their photocatalytic properties are inferior.     

Type-II Red Phosphorus: Wavy Packing of Twisted Pentagonal Tubes

Elemental phosphorus exhibits fascinating structural varieties and versatile properties. The unique nature of phosphorus bonds can lead to the formation of extremely complex structures, and detailed structural information on some phosphorus polymorphs is yet to be investigated. In this study, we investigated an unidentified crystalline phase of phosphorus, type-II red phosphorus (RP), by combining state-of-the-art structural characterization techniques. Electron diffraction tomography, atomic-resolution scanning transmission electron microscopy (STEM), powder X-ray diffraction, and Raman spectroscopy were concurrently used to elucidate the hidden structural motifs and their packing in type-II RP. Electron diffraction tomography, performed using individual crystalline nanowires, was used to identify a triclinic unit cell with volume of 5330 ų, which is the largest unit cell for elemental phosphorus crystals up to now and contains approximately 250 phosphorus atoms. Atomic-resolution STEM imaging, which was performed along different crystal-zone axes, confirmed that the twisted wavy tubular motif is the basic building block of type-II RP. Our study discovered and presented a new variation of building blocks in phosphorus, and it provides insights to clarify the complexities observed in phosphorus as well as other relevant systems.