Adsorption of polyprotic acid at the water/air interface

A rigorous thermodynamic treatment appropriate for surface adsorption from mixed aqueous solution of alkali and polyprotic acid was derived. Those equations were applied to mixed aqueous solution/air systems of alkali metal hydroxide and Fe^III complex with ethylenediamine- N, N, N′,N′-tetraacetate (Fe-EDTA). Surface density of each species arising from Fe-EDTA was separately evaluated, and thus, surface activity of Fe-EDTA was studied, especially its dependence on pH and how it is influenced by the counter cations. Fe-EDTA was positively adsorbed at the water/air interface at very low pHs and negatively at high pHs. The pH range of positive adsorption of Fe-EDTA with potassium ion, as a counter ion, was wider than that with sodium ion. Thus, potassium ion, a structure breaker, tended to smooth surface adsorption of Fe-EDTA at the water/air interface, whereas sodium ion, a structure maker, tended to withdraw Fe-EDTA from the interfacial region.     

Electrophilic amination reactions with 1H-indazole-3-carboxylates: Synthesis of amino acid frameworks and 3-amino-2-oxindoles

Reaction of 1-sulfonylindazole-3-carboxylates with various Grignard reagents effects the N-N bond cleavage of the hydrazone moiety with the first nucleophile and the subsequent N-alkylation gives N,N-dialkylation products in good yields. A new strategy for the synthesis of α-(2-arylsulfonamide)phenylglycine, a precursor to tissue factor/factor VIIa inhibitors is also described. Moreover, the synthesis of quaternary 3-aminooxindoles is developed, utilizing this N,N-dialkylation reaction, followed by intramolecular cyclization/nucleophilic addition reaction.     

Mechanochromic Luminescence Characteristics of Pyridine‐Terminated Chromophores in the Solid State and in a Poly(vinyl alcohol) Matrix

Mechanoresponsive luminophores containing different substituted pyridine rings at the molecular terminus are synthesized and their photoluminescence properties are investigated. The solid chromophore with a 4‐substituted pyridine ring exhibits a reversible photoluminescent color change, while the 2‐substituted chromophore shows only a small change in luminescence, and the 3‐substituted chromophore displays an irreversible photoluminescent color change with mechanical grinding. A change of the sample color in response to mechanical grinding is also achieved for a dye‐dispersed poly(vinyl alcohol) film. Furthermore, a simultaneous acid and mechanoresponsive photoemission color change is achieved in the dye‐dispersed film.     

In-situ observation of graphene growth on Ni(111)

Graphene growth of mono-, bi- and tri-layers on Ni(111) through surface segregation was observed in situ by low energy electron microscopy. The carbon segregation was controlled by adjusting substrate temperature from 1200 K to 1050 K. After the completion of the first layer at 1125 K, the second layer grew at the interface between the first-layer and the substrate at 1050 K. The third layer also started to grow at the same temperature, 1050 K. All the layers exhibited a 1 × 1 atomic structure. The edges of the first-layer islands were straight lines, reflecting the hexagonal atomic structure. On the other hand, the shapes of the second-layer islands were dendritic. The edges of the third-layer islands were again straight lines similar to those of the first-layer islands. The phenomena presumably originate from the changes of interfacial-bond strength of the graphene to Ni substrate depending on the graphene thickness. No nucleation site of graphene layers was directly observed. All the layers expanded out of the field of view and covered the surface. The number of nucleation sites is extremely small on Ni(111) surface. This finding might open the way to grow the high quality, single-domain graphene crystals.     

Positive memory increases cataplexy-like behaviors in narcolepsy mice as revealed using conditioned place preference test

To examine the pathological effect of a mesial temporal seizure onset zone (SOZ) on local and inter-regional response to faces in the amygdala and other structures of the temporal lobe. Intracranial EEG data was obtained from the amygdala, hippocampus, fusiform gyrus and parahippocampal gyrus of nine patients with drug-refractory epilepsy during visual stimulation with faces and mosaics. We analyzed event-related potentials (ERP), gamma frequency power, phase-amplitude coupling and phase-slope-index and compared the results between patients with versus without a mesial temporal SOZ. In the amygdala and fusiform gyrus, faces triggered higher ERP amplitudes compared to mosaics in both patient groups and higher gamma power in patients without a mesial temporal SOZ. In the hippocampus, famous faces triggered higher gamma power for both groups combined but did not affect ERPs in either group. The differentiated ERP response to famous faces in the parahippocampal gyrus was more pronounced in patients without a mesial temporal SOZ. Phase-amplitude coupling and phase-slope-index results yielded bidirectional modulation between amygdala and fusiform gyrus, and predominately unidirectional modulation between parahippocampal gyrus and hippocampus. A mesial temporal SOZ was associated with an impaired response to faces in the amygdala, fusiform gyrus and parahippocampal gyrus in our patients. Compared to this, the response to faces in the hippocampus was impaired in patients with, as well as without, a mesial temporal SOZ. Our results support existing evidence for face processing deficits in patients with a mesial temporal SOZ and suggest the pathological effect of a mesial temporal SOZ on the amygdala to play a pivotal role in this matter in particular.     

Solvent-induced morphological diversification in poly(l-lactide-b-?-caprolactone) block copolymer thin films

Biodegradable block copolymer of poly(l-lactide-b-?-caprolactone) (P(LA-b-CL)) was dissolved in various solvents with different solubility as well as volatility, and spin-cast on a highly oriented pyrolytic graphite (HOPG) to prepare thin films. The surface morphologies were observed by using atomic force microscopy (AFM) in a dynamic force (tapping) mode. Particle like morphology was found in the thin films prepared form the dichloromethane and acetone. Higher volatility of dichloromethane and acetone resulted in the reflection of the particle like objects in the solution to HOPG substrate. In contrast, the P(LA-b-CL)s in toluene and 1,4-dioxane exhibited different morphologies compared to those in dichloromethane and acetone. Lower volatility of toluene and 1,4-dioxane assisted the epitaxial crystallization of PCL component along the HOPG lattice, that was revealed by enzymatic degradation of PLLA component by proteinase K. Thus, adjusting the solubility and solvent volatility for the film formation provided morphological divergence of the P(LA-b-CL) block copolymer, and this technique would be applicable for the surface patterning of biodegradable polymers.     

Controlling the Emergence and Shift Direction of Mechanochromic Luminescence Color of a Pyridine‐Terminated Compound

In this study, mechanochromic luminescence was induced in a complex of mechano‐inactive compounds. Dye/acid complexes containing the same π‐conjugated backbones were prepared. While the luminophore showed blue and red shifts in photoluminescence spectra when combined with different acids by grinding, it exhibited slight mechanoresponsiveness itself. Also, compounds with similar molecular backbones to the dye/acid complex were synthesized to clarify the color change mechanism. The compounds showed both blue and red shifts in photoluminescence and diffuse reflectance spectra upon grinding, indicating that mechanochromic luminescence in the hydrogen‐bonded complex is like its monomeric analogue and that aggregation structure plays an important role in mechanoresponsive behavior rather than the π‐conjugated structure. It was shown that a color change can be mechanically induced by imitating the solid‐state aggregation structure of other mechanoresponsive compounds without synthetic modification.     

Effect of hydrophilicity of polymer particles on their glass transition temperatures in the emulsion state

The glass transition temperatures (Tg) of three kinds of poly(methyl methacrylate)-based copolymer emulsions having wide polymer compositions, which were prepared by emulsifier-free emulsion copolymerizations of methyl methacryalate with ethyl acrylate, n-buthyl methacrylate and methacrylic acid, were measured with a power compensation-type highly sensitive differential scanning calorimeter. The Tg values of the copolymers in their emulsion state (Tg _E) were always lower than those in their dry states (Tg _D), and the difference between Tg _E and Tg _D increased with an increase in copolymer hydrophilicities.Part CCLIII of the series Studies on Suspension and Emulsion     

Changes in gold concentration at the surface of a AuCu alloy sputtered at low temperature

A series of depth profiles in Au_0.56Cu_0.44 produced by bombarding at ? 120°C with an argon ion beam of 2 keV energy and current densities of 4, 6, 12 and 24 μA/cm², respectively, are presented. Gold is enriched in the top layer but the concentration rapidly decreases to a minimum at an average depth of about 2 Å, then increases slowly and saturates at about 30 Å. The change in the composition at this point is called a dip. The magnitude of the dip depends on the ion current density, but the depth is nearly independent of it. Segregation and diffusion effects in establishing the surface composition are stressed.