Direct Asymmetric Mannich‐Type Reaction of α‐Isocyanoacetates with Ketimines using Cinchona Alkaloid/Copper(II) Catalysts

The enantioselective direct Mannich‐type reaction of ketimines with α‐isocyanoacetates has been developed. Excellent yields and enantioselectivity were observed for the reaction of various ketimines and α‐isocyanoacetates using cinchona alkaloid/Cu(OTf)₂ and a base. Both enantiomers of the products could be obtained by using pseudoenantiomeric chiral catalysts. This process offers an efficient route for the synthesis of α,β‐diamino acids.     

pH-responsive non-surface-active/surface-active transition of weakly ionic amphiphilic diblock copolymers

The weakly ionic amphiphilic diblock copolymer polystyrene-b-poly(acrylic acid) was synthesized by nitroxy radical-mediated living radical polymerization with precise control of block length, block ratio, and polydispersity. Systematical surface tension experiments and foam formation observations revealed that this polymer was non-surface active under neutral and alkaline (pH 10) conditions, while it was surface active under an acidic condition (pH 3). This result supports our proposed origin of non-surface activity; the image charge repulsion at the air/water interface is essential in addition to very stable micelle formation in the bulk solution. At a higher pH (pH 12), the polymer showed slight surface activity since the added NaOH played a role as an added salt. The critical micelle concentration (cmc) was estimated by static light scattering. Cmc increased with increasing added salt (NaCl) concentration as was observed for other strongly ionic non-surface-active polymers. Hence, this trend is characteristic for non-surface-active polymers. The pH dependence of cmc was minimum at pH 8–10. Since the acrylic acid block is fully ionized under this condition, the strong image charge repulsion at this condition accelerated micelle formation at a low polymer concentration, which consequently decreased cmc. Micelles in bulk solution were confirmed by dynamic light scattering, and the salt concentration and pH dependencies of the hydrodynamic radius of the micelles were also estimated. The pH-responsive non-surface-active/surface-active transition observed in this study strongly supports the fact that the image charge repulsion is an essential factor for non-surface activity in addition to stable micelle formation in solution.     

Electrochemical Sensing of Ovalbumin Based on the Interaction between Lysozyme Origin/Tyrosine‐rich Peptides Modified on Magnetic Beads and Oligothreonine/Ovalbumin‐origin Peptide

We developed a highly sensitive electrochemical system for the sensing of ovalbumin (OVA). Lysozyme origin/tyrosine‐rich peptides (RNRCKGTDVQAWY₄C) were immobilized on magnetic beads, and the competitive reaction between OVA and oligothreonine/OVA origin peptide probe (T₈VLLPDEVSG) could then be measured. In a previous study, the detection of OVA at the 10^?13 M level was achieved using RNRCKGTDVQAWY₄C‐modified beads via a cross‐linker. To improve the sensitivity to OVA, this system uses T₈VLLPDEVSG peptide probe to measure the interaction to RNRCKGTDVQAWY₄C immobilized on magnetic beads. The peak of Y₄C actually was an electron‐transfer peptide, which represented the oxidation of a phenolic hydroxyl group. First, we confirmed that the oxidation response of Y₄C was increased based on an improvement in the electron transfer accessibility by oligothreonine. Next, T₈VLLPDEVSG peptide probe was used for the electrochemical sensing of OVA in solutions that contained consistent amounts of RNRCKGTDVQAWY₄C on magnetic beads. As a result, the peak current decreased as the concentration of OVA increased. The sensitivity to OVA was improved compared with the use of only RNRCKGTDVQAWY₄C on magnetic beads. The OVA detection level was 10^?14 M, which approximates the results from antibody‐antigen reactions. Consequently, the proposed system is a powerful new concept in protein sensing.     

Catalytic Carbonylation and Carboxylation of Organosulfur Compounds via C−S Cleavage

Transition‐metal‐catalyzed carbonylation with CO gas occupies a privileged position in organic synthesis for the synthesis of carbonyl compounds. Although this attractive and useful chemistry has led many researchers to investigate carbonylative transformations of various organic (pseudo)halides, C?S‐cleaving carbonylation of organosulfur compounds has been fairly limited. Recently, a broad spectrum of C?S‐cleaving transformations has been emerging in the field of cross‐coupling. In light of the importance of carbonyl compounds as well as considerable advancement for employing organosulfur compounds as competent surrogates of (pseudo)halides, carbonylative transformations of C?S bonds should be of high value. This Minireview focuses on catalytic C?S carbonylation of organosulfur compounds with CO or its equivalents. In addition, reductive carboxylation of C?S bonds with CO₂ is described.     

Palladium‐Catalyzed C−H Iodination of Arenes by Means of Sulfinyl Directing Groups

C?H iodination of aromatic compounds has been accomplished with the aid of sulfinyl directing groups under palladium catalysis. The reaction proceeds selectively at the peri‐position of polycyclic aryl sulfoxides or at the ortho‐position of phenyl sulfoxides. The iodination products can be further converted via iterative catalytic cross‐coupling at the expense of the C?I and C?S bonds. Computational studies suggest that peri‐C?H palladation would proceed via a non‐directed pathway, wherein neither of the sulfur nor oxygen atom of the sulfinyl group coordinates to the palladium before and at the transition state.     

A new application of statistical moment theory to evaluate the swelling behavior of thermo-responsive gels

The loosely cross-linked poly(acryloyl-L -proline methyl ester) gel, which is known as one of the typical thermo-responsive gels, shows a volume transition around approximately 14°C in pure water. This volume transition is shifted to higher temperature by treatment in aqueous sodium dodecyl sulfate (SDS). The analysis of the swelling-temperature curve (frequency distribution) was performed according to a moment analysis, in which the area under the swelling-temperature curve (AUC), mean swelling transition temperature (MSTT) and variance of swelling transition temperature (VSTT) were calculated. It is shown that the apparent volume transition temperature can be estimated from MSTT and that VSTT can be used to characterize the shape of the corresponding curves.     

Matrix-isolation and electronic structure of vinyl-substituted silylenes and their complexes with bases [1]

Vinyl-substituted silylenes, 2,5-bis(methylene)-1-silacyclopentane-1,1-diyl ( 1 ) and 2-methylene-1-silacyclopentane-1,1-diyl ( 2 ), generated photochemically from the corresponding trisilanes in 3-methylpentane (3-MP) at 77 K, showed broad bands at 505 and 475 nm, respectively, which were assigned to the n(Si)-3p(Si) transition. The origin of the red shift in the n(Si)-3p(Si) transition is ascribed to the significant lowering of the 3p(Si) orbital level caused by the vinyl substitution on the silylene; the relatively high-lying 3p(Si) orbital can interact more effectively with the antibonding π* orbital than with the bonding π orbital of the vinyl group. The absorption spectra for 1 and 2 in the presence of several bases in 3-MP glass matrix shifted significantly to blue due to the formation of the corresponding base complexes. Analysis of the spectral change of the silylenes upon complexation with bases was very constructive for the understanding of the structural characteristics of substituted silylenes.     

Effects of Roxadustat on Erythropoietin Production in the Rat Body

Anemia is a major complication of chronic renal failure. To treat this anemia, prolylhydroxylase domain enzyme (PHD) inhibitors as well as erythropoiesis-stimulating agents (ESAs) have been used. Although PHD inhibitors rapidly stimulate erythropoietin (Epo) production, the precise sites of Epo production following the administration of these drugs have not been identified. We developed a novel method for the detection of the Epo protein that employs deglycosylation-coupled Western blotting. With protein deglycosylation, tissue Epo contents can be quantified over an extremely wide range. Using this method, we examined the effects of the PHD inhibitor, Roxadustat (ROX), and severe hypoxia on Epo production in various tissues in rats. We observed that ROX increased Epo mRNA expression in both the kidneys and liver. However, Epo protein was detected in the kidneys but not in the liver. Epo protein was also detected in the salivary glands, spleen, epididymis and ovaries. However, both PHD inhibitors (ROX) and severe hypoxia increased the Epo protein abundance only in the kidneys. These data show that, while Epo is produced in many tissues, PHD inhibitors as well as severe hypoxia regulate Epo production only in the kidneys.     

Electron beam treatment of lignite-burning flue gas with high concentrations of sulfur dioxide and water

Experiments were carried out to investigate the removals of SO₂ and NO_x from simulated lignite-burning flue gas containing SO₂ (4800 ppm), NO (320 ppm) and H₂O (22%) by electron beam irradiation. Removal efficiencies of SO₂ and NO_x were achieved to reach 97 and 88% at 70°C, and 74 and 85% at 80°C, respectively, with the dose of 10.3 kGy without NH₃ leakage. The higher removal efficiencies of SO₂ and NO_x were observed in simulated lignite-burning flue gas than in coal-fired flue gas containing 800 ppm of SO₂, 225 ppm of NO and 7.5% H₂O at the same treatment condition. The higher removal efficiencies were attributed to the higher concentrations of SO₂, H₂O, and added NH₃. Simulation calculations indicated that the higher concentrations of these components enhance the effective radical reactions to oxidize NO to form NO₂ with HO₂ radical, and to oxidize SO₂ to form SO₃ with OH radical and O₂. The reactions of NO_x with N and NH₂ radicals to produce N₂ and N₂O also promote the NO_x removal. By-product was determined to be the mixture of (NH₄)₂SO₄ and NH₄NO₃ containing a small amount of H₂SO₄.     

Analysis of Individual High-Frequency Traders’ Buy–Sell Order Strategy Based on Multivariate Hawkes Process

Traders who instantly react to changes in the financial market and place orders in milliseconds are called high-frequency traders (HFTs). HFTs have recently become more prevalent and attracting attention in the study of market microstructures. In this study, we used data to track the order history of individual HFTs in the USD/JPY forex market to reveal how individual HFTs interact with the order book and what strategies they use to place their limit orders. Specifically, we introduced an 8-dimensional multivariate Hawkes process that included the excitations due to the occurrence of limit orders, cancel orders, and executions in the order book change, and performed maximum likelihood estimations of the limit order processes for 134 HFTs. As a result, we found that the limit order generation processes of 104 of the 134 HFTs were modeled by a multivariate Hawkes process. In this analysis of the EBS market, the HFTs whose strategies were modeled by the Hawkes process were categorized into three groups according to their excitation mechanisms: (1) those excited by executions; (2) those that were excited by the occurrences or cancellations of limit orders; and (3) those that were excited by their own orders.