Discussion on Ohta et al., “Traveling bands in self-propelled soft particles”

A discussion on the contribution of Ohta and Yamanaka [1] in this special issue, supplemented by new agent-based simulations of band collisions within the standard Vicsek-model.     

Dipolar organic pyridyl dyes for dye-sensitized solar cell applications

New dipolar dyes containing arylamine as the electron donor, 2-cyanoacrylic acid as the acceptor, and a conjugated spacer with incorporation of 2,5-pyridyl entity have been synthesized. Photophysical and electrochemical measurements, and theoretical computation were carried on these dyes. The solar cell devices using these dyes as the sensitizers exhibited light-to-electricity efficiencies in the range of 4.28–5.27%, which reaches 60–72% of N719-based device fabricated and measured under similar conditions. Better DSSC performance can be achieved with the dye where pyridine group is attached to thienyl or fluorenyl group because of favorable resonance energy and/or coplanarity for more effective charge transfer.     

Nanotribological behavior of thermal treatment of zinc titanate thin films

We present a study of the nanotribological behavior of ZnTiO₃ films; the surface morphology, stoichiometry, and friction (μ) were analyzed using atomic force microscopy, X‐ray photoelectron spectroscopy, and nanoscratch system. It is confirmed that the measured values of H and μ of the ZnTiO₃ films were in the range from 8.5 ± 0.4 to 5.6 ± 0.4 GPa and from 0.164 to 0.226, respectively. It is suggested that the hexagonal ZnTiO₃ decomposes into cubic Zn₂TiO₄ and rutile TiO₂ based on the thermal treatment; the H, μ, and R_MS were changed owing to the grain growth and recovery that results in a relax crystallinity of ZnTiO₃ films. From X‐ray photoelectron spectroscopy measured, core levels of O 1 can attribute the weaker bonds as well as lower resistance after thermal treatment. The XRD patterns showed that as‐deposited films are mainly amorphous; however, the hexagonal ZnTiO₃ phase was observed with the ZnTiO₃ (104), (110), (116), and (214) peaks from 620 to 820 °C, indicating that there is highly (104)‐oriented ZnTiO₃ on the silicon substrate. Copyright © 2012 John Wiley & Sons, Ltd.     

Imaging cytoplasmic cAMP in mouse brainstem neurons

Background  

cAMP is an ubiquitous second messenger mediating various neuronal functions, often as a consequence of increased intracellular Ca²⁺ levels. While imaging of calcium is commonly used in neuroscience applications, probing for cAMP levels has not yet been performed in living vertebrate neuronal tissue before.     

Stacking Structure of Confined 1‐Butanol in SBA‐15 Investigated by Solid‐State NMR Spectroscopy

Understanding the complex thermodynamic behavior of confined amphiphilic molecules in biological or mesoporous hosts requires detailed knowledge of the stacking structures. Here, we present detailed solid‐state NMR spectroscopic investigations on 1‐butanol molecules confined in the hydrophilic mesoporous SBA‐15 host. A range of NMR spectroscopic measurements comprising of ¹H spin–lattice (T₁), spin–spin (T₂) relaxation, ¹³C cross‐polarization (CP), and ¹H,¹H two‐dimensional nuclear Overhauser enhancement spectroscopy (¹H,¹H 2D NOESY) with the magic angle spinning (MAS) technique as well as static wide‐line ²H NMR spectra have been used to investigate the dynamics and to observe the stacking structure of confined 1‐butanol in SBA‐15. The results suggest that not only the molecular reorientation but also the exchange motions of confined molecules of 1‐butanol are extremely restricted in the confined space of the SBA‐15 pores. The dynamics of the confined molecules of 1‐butanol imply that the ¹H,¹H 2D NOESY should be an appropriate technique to observe the stacking structure of confined amphiphilc molecules. This study is the first to observe that a significant part of confined 1‐butanol molecules are orientated as tilted bilayered structures on the surface of the host SBA‐15 pores in a time‐average state by solid‐state NMR spectroscopy with the ¹H,¹H 2D NOESY technique.     

Synthesis and characterization of cyclometalated iridium(III) complexes containing pyrimidine-based ligands

New pyrimidine derivatives (pyr) have been synthesized using palladium-catalyzed Suzuki coupling reaction. These compounds can undergo cyclometalation with iridium trichloride to form bis-cyclometalated iridium complexes, (pyr)₂Ir(acac) (acac = acetylacetonate; pyr = cyclometalated pyr). The substituents at the both cyclometalated phenyl ring and pyrimidine ring were found to affect both electrochemical and photophysical properties of the complexes. Computation results on these complexes are consistent with the electrochemical and photophysical data. The complexes are green-emitting with good solution quantum yields at ∼0.30. Light-emitting devices using these complexes as dopants were fabricated, and the device performance at 100 mA/cm² are moderate: 9 (17 481 cd/m², 4.8%, 18 cd/A, 5.1 lm/W); 10 (18 704 cd/m², 4.9%, 18.9 cd/A, 4.7 lm/W); 13 (20 942 cd/m², 5.4%, 21.0 cd/A, 6.1 lm/W).     

Using subcritical/supercritical fluid chromatography to separate acidic,basic, and neutral compounds over an ionic liquid-functionalized stationary phase

We packed an ionic liquid (IL)-functionalized stationary phase – based on 1-octyl-3-propylimidazolium chloride covalently bounded to silica gel – into a 3.2 mm × 250 mm column for the simultaneous separation of acidic, basic, and neutral compounds using carbon dioxide subcritical/supercritical fluid chromatography (SFC), and examined the effects of the pressure, temperature, co-solvents, and additives on the retention behavior of the analytes. The model compounds tested for SFC separation are acetaminophen, metoprolol, fenoprofen, ibuprofen, naphthalene, and testosterone. The data indicate that hydrogen-bonding and hydrophobic interactions between the analytes and the IL-modified stationary phase seem to involve in the separation process. Simultaneous separation of acidic, basic, and neutral compounds via SFC was successful at a co-solvent content of 20% MeOH, a pressure of 110 bar, and a column temperature of 35 °C. The relative standard deviations of the retention times and peak areas at 50 ppm were all less than 4 and 8% (n = 6), respectively.     

Unusual temperature gap in turbulent drag reduction of cationic surfactants with mixed counterions

Unusual temperature gaps have previously been observed in the turbulent drag reduction effectiveness of Dobon and Habon cationic surfactant systems containing two anionic counterions of different binding strengths. Here, we report drag reduction data for a cationic surfactant with a mixture of dodecyl sulfate and tosylate counterions showing a temperature gap. Cryo-TEM images of nanostructures at different temperatures for this system support an explanation for this gap, based on the counterions’ relative binding strengths.     

Milestones in electron crystallography

Electron crystallography determines the structure of membrane embedded proteins in the two-dimensionally crystallized state by cryo-transmission electron microscopy imaging and computer structure reconstruction. Milestones on the path to the structure are high-level expression, purification of functional protein, reconstitution into two-dimensional lipid membrane crystals, high-resolution imaging, and structure determination by computer image processing. Here we review the current state of these methods. We also created an Internet information exchange platform for electron crystallography, where guidelines for imaging and data processing method are maintained. The server (http://2dx.org) provides the electron crystallography community with a central information exchange platform, which is structured in blog and Wiki form, allowing visitors to add comments or discussions. It currently offers a detailed step-by-step introduction to image processing with the MRC software program. The server is also a repository for the 2dx software package, a user-friendly image processing system for 2D membrane protein crystals.