2,6‐Bis(amido)benzoic Acid with Internal Hydrogen Bond as Brønsted Acid Catalyst for Friedel–Crafts Reaction of Indoles

Benzoic acid catalysts bearing two amide groups that increase the Brønsted acidity of the carboxylic acid moiety by internal hydrogen‐bonding interactions were designed as a novel class of carboxylic acid catalysts for the Friedel–Crafts reaction of indoles with β‐nitrostyrenes and 3,3‐disubstituted 3H‐indoles to obtain the corresponding Friedel–Crafts adducts in high yields. The internal hydrogen‐bonding benzoic acid catalysts have a relatively high Brønsted acidity compared with benzoic acid based on the pK_a measurements in DMSO by UV spectrophotometric titration.

     

Assemblies of biomaterials in mesoporous media

Assemblies of biomaterials onto mechanically stable inorganic structure are advantageous for the practical applications because of the potential to improve the stability and performance of biomaterials in the biocatalytic processes. Among many kinds of inorganic materials, mesoporous materials such as mesoporous silica and mesoporous carbon have attracted special attention owing to their well-defined structures and perfectly controlled pore geometries, which would lead to unique functions such as size selective adsorption of biomaterials. In the first part of this review, adsorption behaviors of proteins, enzymes, vitamins, and amino acids in aqueous solutions onto mesoporous media are systematically explained. Pore geometries (pore diameter and volume) of mesoporous materials are the crucial factors for the size selective adsorption of biomaterials, especially proteins, which often have a size comparable to pore dimension. The studies on the adsorption of biomaterials on the mesoporous carbon reveal that hydrophobic interaction between guest molecules and surface of the mesoporous materials is an important parameter which controls the amount of biomaterials adsorption. Enhanced adsorption of biomaterials was commonly observed at their isoelectric point, where electrostatic repulsion is minimized between the biomaterials. In addition, several functions such as biomolecular separation, reactor function, controlled drug release, and photochemical properties are discussed in the latter sections. Studies on assemblies of biomaterials in mesoporous media are still in initial stage, but the development of appropriately designed mesoporous materials would powerfully promote researches in these fascinating unexplored fields.     

Remarkable difference of phase transition behaviors between Langmuir monolayers and aqueous bilayer vesicles of oligopeptide-carrying lipids

In this research, we synthesized six kinds of oligopeptide-carrying lipids which possessing glycine, diglycine, triglycine, alanine, dialanine, and trialanine residues (see Figure 1 for their formulae), and systematically investigated their phase transition behaviors both at the air-water interface and in aqueous bilayer vesicles. pi-A Isotherms of Langmuir monolayers of these lipids were measured at the air-water interfaces under varied temperature conditions and were analyzed based on compressibility of the monolayers. Above the specific temperature, the transition pressure from its expanded phase to condensed phase is not distinguishable with the collapse pressure of the monolayer, i.e., the monolayer collapses directly from the expanded phase without forming the condensed phase. This temperature was defined as the phase transition temperature of the monolayer, which was compared with the phase transition temperature of the corresponding bilayer vesicle in water. The phase transition temperatures of the oligoglycine-carrying lipids and oligoalanine-carrying lipids are significantly different at the air-water interface, while the corresponding difference is not obvious in their aqueous bilayer vesicles. Consideration based on molecular structures suggests necessity of the water mediation for effective formation of hydrogen bonding between the oligopeptide residues directly connected to dialkyl chains. Therefore, the differences in water accessibility to the films may cause the difference of the phase transition behaviors of the oligopeptide-carrying lipids between the Langmuir monolayers and the aqueous bilayer vesicles. Although the proposed mechanism is not fully supported by experimental evidences, the data presented here clearly demonstrated the presence of significant difference of the phase transition properties between the Langmuir monolayers at the air-water interface and aqueous bilayer vesicles of the oligopeptide-carrying lipids.     

Structure and rheology of charge-free reverse micelles in aromatic liquid phenyloctane

Reverse micelles formulation requires an inclusion of water or other polar molecules in the binary mixture of ionic surfactant and oil and generally exhibit spheroid geometry with a small aggregation number. Here, we report structure and rheology of charge-free (nonionic) reverse micelles in surfactant/oil systems. We have systematically investigated intrinsic parameters for the shape, size, and internal cross section structure control of such micelles using small-angle X-ray scattering (SAXS) and the rheometry. We found that diglycerol monomyristate (C14G2) when added into an aromatic organic liquid phenyloctane, spontaneously self-assembles into spheroid micelles with maximum diameter ca. 6.7 nm. Decrease in surfactant chain length favors globular-to-rod type transition and micellar aggregation number (N(agg)) increases significantly. On the other hand, increase in surfactant weight fraction induces one-dimensional (1-D) micellar growth; N(agg) increases in parallel to the surfactant concentration. Reverse micelles shrink with the rise of temperature, which is close to the rod-to-sphere type transition. However, water causes a significant micellar growth; N(agg) increases drastically, which shows that water not only increase reverse micellar size but also increases the number of surfactant molecules per micelle. All these microstructure transitions could be understood in terms of the modification of the critical packing parameter (cpp). The SAXS results are very well supported by the geometrical model fittings and rheometry.     

Cigarette smoke extract enhances oxytocin-induced rhythmic contractions of rat and human preterm myometrium

Although smoking during pregnancy is a major risk factor for preterm delivery, the underlying mechanism by which smoking stimulates uterine contractions is still poorly understood. In the present study, we tried to clarify the effects of smoking on myometrial contractility induced by oxytocin (OT) using cigarette smoke extract (CSE). Myometrial strips, which were taken from the rat on day 16 of pregnancy, and from human preterm and term delivery groups, were incubated overnight with several doses of CSE at 37 degrees C under non-hormonal conditions. The uterine contractile sensitivity and activity (force and frequency) upon exposure to OT were investigated. Furthermore, the expression levels of oxytocin receptor (OTR) mRNA in the myometrial strips were investigated by real-time PCR. Contractile sensitivity to OT in the rat CSE (10(-7) pieces/ml) group was found to be significantly higher than in the control group (P < 0.05). Contractile activity did not differ between the CSE and control groups. The expression levels of rat OTR mRNA in the CSE (10(-7) pieces/ml) group were significantly higher than in the control group (P < 0.01). Similarly, in preterm myometrial strips, the expression levels of human OTR mRNA in the CSE (10(-7) pieces/ml) group were significantly higher than in the control group (P < 0.05). These findings suggest that CSE directly increases the contractile sensitivity of preterm myometrium in response to OT by upregulating the expression of OTR mRNA and thereby increases the risk of preterm delivery in women, who smoke during pregnancy.     

Diploid porcine parthenotes produced by inhibition of first polar body extrusion during in vitro maturation of follicular oocytes

We investigated nuclear progression and in vitro embryonic development after parthenogenetic activation of porcine oocytes exposed to cytochalasin B (CB) during in vitro maturation (IVM). Nuclear progression was similar in control oocytes and oocytes matured in the presence of 1 microg/ml CB (IVM-CB group) by 37 h IVM; at this time the proportion of oocytes that had reached or passed through the anaphase-I stage did not differ significantly between the IVM-CB and the control groups (61.3 and 69.9% respectively; P < 0.05). After IVM for 37 h, no polar body extrusion was observed in the IVM-CB group. In these oocytes, the two lumps of homologous chromosomes remained in the ooplasm after their segregation and turned into two irregular sets of condensed chromosomes. By 41 h IVM, the double sets of chromosomes had reunited in 89.5% IVM-CB oocytes and formed a single large metaphase plate, whereas 68.8% of the control oocytes had reached the metaphase-II stage by this time. When IVM-CB oocytes cultured for 46 h were stimulated with an electrical pulse and subsequently cultured for 8 h without CB, 39.0% of them extruded a polar body and 82.9% of them had a female pronucleus. Chromosome analysis revealed that the majority of oocytes that extruded a polar body were diploid in both the control and the IVM-CB groups. However, the incidence of polyploidy in the IVM-CB group was higher than that in the control group (P < 0.05). In vitro development of diploid parthenotes in the control and the IVM-CB groups was similar in terms of blastocyst formation rates (45.8 and 42.8% respectively), number of blastomeres (39.9 and 44.4 respectively), the percentage of dead cells (4.3 and 2.9% respectively), and the frequency of apoptotic cells (7.3 and 6.3% respectively). Tetraploid embryos had a lower blastocyst formation rate (25.5%) and number of cells (26.2); however, the proportion of apoptotic nuclei (7.0%) was similar to that in diploid parthenotes. These results suggest that the proportion of homozygous and heterozygous genes does not affect in vitro embryo development to the blastocyst stage.     

Destabilization of cubic-stabilized zirconia electrolyte induced by boron oxide under reducing atmosphere

The stability of yttria-stabilized zirconia (YSZ) and scandia-stabilized zirconia (ScSZ) electrolytes against boron oxide was examined. Boron oxide was painted on the polished surface of YSZ and ScSZ and annealed at 1273 K for 100 h under wet hydrogen flowing condition. The X-ray diffractometry, scanning electron microscopy/energy dispersive X-ray analysis, and Raman studies revealed that formation of Y₂O₃ and Sc₂O₃ occurred on YSZ and ScSZ surfaces contacting the boron oxide, but rare earth borates were not observed. The surface of electrolytes around precipitated particles became rough and phase transformation was confirmed from the cubic to the tetragonal or the monoclinic phases due to stabilizer removal from cubic zirconia. It has been also verified that small amounts of zirconium and yttrium were transported from the electrolyte to the gas phase via boron component. This destabilization effect induced by boron oxide was more serious for ScSZ than for YSZ. A destabilization mechanism under wet hydrogen atmosphere is proposed based on pseudo ternary phase diagrams for the YO_1.5–BO_1.5–ZrO₂ system and the ScO_1.5–BO_1.5–ZrO₂ system and thermodynamic considerations.     

Stress intensity factor evaluation of a circumferential crack in a finite length thin-walled cylinder for arbitrarily distributed stress on crack surface by weight function method

A weight function to evaluate the stress intensity factor (SIF) of a circumferential crack, subjected to arbitrarily distributed stress on the crack surfaces, in a finite length thin-walled cylinder was derived based on the closed form SIF equation previously developed by the authors. It is easy to evaluate the effects of structural parameters and stress distribution on the SIF with this weight function. Numerical examples confirmed the validity of the weight function. These examples showed that the effect of cylinder length on the SIF is quite large.     

Developments in Molecular Recognition and Sensing at Interfaces

In biological systems, molecular recognition events occur mostly within interfacial environments such as at membrane surfaces, enzyme reaction sites, or at the interior of the DNA double helix. Investigation of molecular recognition at model interfaces provides great insights into biological phenomena. Molecular recognition at interfaces not only has relevance to biological systems but is also important for modern applications such as high sensitivity sensors. Selective binding of guest molecules in solution to host molecules located at solid surfaces is crucial for electronic or photonic detection of analyte substances. In response to these demands, molecular recognition at interfaces has been investigated extensively during the past two decades using Langmuir monolayers, self-assembled monolayers, and lipid assemblies as recognition media. In this review, advances of molecular recognition at interfaces are briefly summarized.     

Redrawing analysis of aluminum–stainless-steel laminated sheet using FEM simulations and experiments

The behavior of two-layer aluminum–stainless-steel (AL-SUS) laminated sheets during deep drawing, direct and reverse redrawing processes (first and second drawing stages), have been examined by simulations and laboratory experiments. For the simulation a rigid-plastic finite element program has been used. The results of simulations are presented as the variation of drawing ratios with respect to various thickness ratios and setting conditions. They show that to achieve the highest drawing ratios in direct and reverse redrawing, the thickness ratio should be about (one-layer aluminum and three-layer stainless-steel) and the setting conditions are opposite to each other. Considering the FEM results, laminated sheets with a thickness ratio of 71.3% aluminum and 28.7% stainless-steel were used to prepare deep drawing and redrawing experiments. The results of experiments are presented as the variation of thickness strain distribution in the drawn cup and punch load–stroke curves with respect to the setting condition. Results show that while in direct redrawing, contact of stainless-steel with the punch leads to the maximum drawing ratio, in reverse redrawing, aluminum should contact the punch in order to achieve the highest drawing ratio. An explanation for this finding is offered based on the thickness strain distribution, and punch load–stroke curves.