Design and Synthesis of Chiral Zn2+ Complexes Mimicking Natural Aldolases for Catalytic C–C Bond Forming Reactions in Aqueous Solution

Extending carbon frameworks via a series of C–C bond forming reactions is essential for the synthesis of natural products, pharmaceutically active compounds, active agrochemical ingredients, and a variety of functional materials. The application of stereoselective C–C bond forming reactions to the one-pot synthesis of biorelevant compounds is now emerging as a challenging and powerful strategy for improving the efficiency of a chemical reaction, in which some of the reactants are subjected to successive chemical reactions in just one reactor. However, organic reactions are generally conducted in organic solvents, as many organic molecules, reagents, and intermediates are not stable or soluble in water. In contrast, enzymatic reactions in living systems proceed in aqueous solvents, as most of enzymes generally function only within a narrow range of temperature and pH and are not so stable in less polar organic environments, which makes it difficult to conduct chemoenzymatic reactions in organic solvents. In this review, we describe the design and synthesis of chiral metal complexes with Zn²⁺ ions as a catalytic factor that mimic aldolases in stereoselective C–C bond forming reactions, especially for enantioselective aldol reactions. Their application to chemoenzymatic reactions in aqueous solution is also presented.     

Controlling the drying process in vacuum foam drying under low vacuum conditions by inducing foaming by needle stimulation of the solution

Abstract

Vacuum foam drying is a promising drying technique but an extremely high vacuum is needed to achieve “foaming.” The findings reported herein show that, when a solution is partially vacuum-dried to 0.05–2?g-solvent/g-dry matter (initial drying) and the solution is then punctured with a steel needle (needle stimulation), vacuum drying resumes as a result of the solution foaming, even under conditions of an insufficient vacuum (ca. 1,000?Pa) where foaming is minimal. Methanol, ethanol, and isopropanol were used as solvents, and sugar and different molecular weight polyvinylpyrrolidone were employed as solutes. The results indicate that needle puncturing introduces minute bubbles, which then triggers foaming.     

Terahertz Oscillating Devices Based Upon the Intrinsic Josephson Junctions in a High Temperature Superconductor

Recent developments of coherent terahertz (THz) oscillators based on the intrinsic Josephson junctions (IJJs) in mesas of the high temperature superconductor Bi₂Sr₂CaCu₂O_8+δ are reviewed. Experimental and theoretical studies of the emission from equilateral, right-angled isosceles, and acute isosceles triangular mesas are compared with those obtained from rectangular, square, and disk mesas, in order to determine the role of the mesa geometry. The superconducting properties and emission frequency f spectra are presented for a variety of triangular mesa geometries. Analytic and finite difference time domain numerical calculations of the emissions from the internal electromagnetic (EM) cavity modes of triangular mesas are compared with experiment. The experimental f always satisfies the ac Josephson relation, and its narrow linewidth arises from the synchronized emissions from many IJJs. For some mesa geometries, f also strongly locks onto an EM cavity mode frequency, enhancing the emission’s stability and output power. For other geometries, such cavity mode locking is weak, and f is highly tunable.     

Conformational Analysis of Misfolded Protein Aggregation by FRET and Live-Cell Imaging Techniques

Cellular homeostasis is maintained by several types of protein machinery, including molecular chaperones and proteolysis systems. Dysregulation of the proteome disrupts homeostasis in cells, tissues, and the organism as a whole, and has been hypothesized to cause neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS) and Huntington’s disease (HD). A hallmark of neurodegenerative disorders is formation of ubiquitin-positive inclusion bodies in neurons, suggesting that the aggregation process of misfolded proteins changes during disease progression. Hence, high-throughput determination of soluble oligomers during the aggregation process, as well as the conformation of sequestered proteins in inclusion bodies, is essential for elucidation of physiological regulation mechanism and drug discovery in this field. To elucidate the interaction, accumulation, and conformation of aggregation-prone proteins, in situ spectroscopic imaging techniques, such as Förster/fluorescence resonance energy transfer (FRET), fluorescence correlation spectroscopy (FCS), and bimolecular fluorescence complementation (BiFC) have been employed. Here, we summarize recent reports in which these techniques were applied to the analysis of aggregation-prone proteins (in particular their dimerization, interactions, and conformational changes), and describe several fluorescent indicators used for real-time observation of physiological states related to proteostasis.     

Effect of a body-tie structure fabricated by partial trench isolation on the suppression of floating body effect induced soft errors in SOI SRAM investigated using nuclear probes

Soft errors induced by proton, helium and oxygen ion irradiations were measured as a function of distance between a body electrode under partial trench isolation and a metal pad connected to a tungsten via for the first metal layer of a silicon-on-insulator (SOI) static random access memory. Abnormal drain charges induced by ion irradiations with various distances in the SOI metal oxide semiconductor field effect transistor were simulated to be compared with the experimental results. The soft errors were found to depend on the distance between the body electrode and the metal pad in the case of the abnormal drain charge, which is induced by incident ions, lower than the critical charge of the SRAM cells. The soft errors did not depend on the distance for the abnormal drain charges higher than the critical charge.     

Stator‐core structure and winding technology for EPS motors

Electric power steering (EPS) motors must have the performance characteristics of precision machines. They should be compact and produce high power. Moreover, the loss torque and the change of loss torque should be as low as possible. In this study, dividing the stator core into small blocks and winding the coils densely on the blocks are shown to be effective techniques for achieving compact high‐power motors. We examined whether I‐shaped divided cores or T‐shaped divided cores were more suitable for EPS motors in terms of motor performance and production cost. We built two experimental motors, one with I‐shaped divided cores and the other with T‐shaped divided cores, and measured three important characteristics of EPS motors: output torque, loss torque, and loss torque change. The T‐type motor proved to have better performance for all three characteristics. Moreover, the productivity of the T‐type motor was shown to be higher than that of the I‐type motor, indicating that overall, T‐shaped divided cores are advantageous for the stators of EPS motors. Next, we considered a new winding method for the continuous winding of two T‐shaped cores in order to achieve a compact terminal connection board. The extending lines made by the new winding method do not extend beyond the coil end. Therefore, this method will contribute to reduction of the axial dimension of EPS motors. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(1): 35–42, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21085     

Fast computation and stable convergence technique for unbalanced load flow calculation in large‐scale systems

This paper presents a new method of unbalanced load flow calculation to improve complexity by the method of advanced symmetrical coordinates. Usually, the electric power system has been calculated only by the positive phase sequence component on the assumption that three‐phase transmission lines and loads are balanced. However, many ultrahigh‐voltage transmission lines are not transposed, and therefore mutual inductances cause negative sequence currents in the trunk transmission system. Negative sequence currents cause heating of generators and transformers, and therefore the three‐phase sequence component should be calculated accurately. We examined the fast computation and good convergence performance of unbalanced load flow calculation by models of three‐phase transmission lines, transformers, and loads. The proposed method is not the phase coordinate system but the method of symmetrical coordinates. This technique decreases numerical complexity by the use of a simplified Jacobian matrix. The convergence performance of this method is inferior to that of the usual Newton–Raphson method. As a consequence, the problem of poor convergence performance is alleviated by a technique for the newly developed deceleration Newton method. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(1): 17–24, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21034     

Steam Reforming of Glycerin Using Ni-based Catalysts Loaded on CaO–ZrO2 Solid Solution

Abstract  

Steam reforming of glycerin on Ni-loaded catalyst was performed using a ZrO₂-based support material. The addition of CaO to ZrO₂ improved the catalyst performance, and NiO/CaO–ZrO₂ afforded glycerin conversion of 88.9% with an H₂ yield of 75.3% at 600 °C. Carbon formation decreased from 4.2 to 2.0% with CaO-added catalyst. Solid solution was formed with the addition of CaO to ZrO₂, and it exhibited basic characteristics. Further reduction of carbon formation during the reforming reaction was achieved by using a quaternary complex oxide catalyst NiO–CeO₂/CaO–ZrO₂, where glycerin conversion of 96.1% and a H₂ yield of 83.7% were achieved with carbon formation of 0.7% at 600 °C.     

The method for surface functionalization of single-walled carbon nanotubes with fuming nitric acid

Surface functionalization of single-walled carbon nanotubes (SWCNTs) was carried out using fuming nitric acid as a NO₂ radical source. The surface double bonds of the SWCNTs reacted with the NO₂ radicals at 10–90 °C under sonication, and following treatment with aqueous NaOH yielded modified carbon nanotubes with high affinity for polar solvents such as dimethylformamide. The structure of the product was characterized using Fourier transform-infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, and atomic force microscopy. FT-IR and XPS spectra revealed the product has OH groups (3400, 1200 cm⁻¹), which was expected due to the addition of NO₂ radicals to the surface double bonds and subsequent substitution with OH groups. C_1s curve fitting analysis of the XPS spectra was used to quantitatively determine the different functional groups on the surface, and the amount of COOH groups was found to be increased from 2.8% to 9.3% due to progressive oxidation by increasing the reaction temperature from 10 to 90 °C.     

Design for improved adhesion of fluorine-incorporated hydrogenated amorphous carbon on metallic stent: Three-layered structure with controlled surface free energy

Hydrogenated amorphous carbon (a-C:H) or element-incorporated a-C:H have attracted much attention as coating materials on coronary artery stents owing to their outstanding properties. However, their applications have been limited because of poor adhesion to metallic materials. The present work was thus aimed at improving the adhesive property of a-C:H-based film on a stent by introducing interlayers with controlled surface free energies.Here we propose a three-layered coating for a SUS316L stent, comprising fluorine-incorporated a-C:H (a-C:H:F), silicon-incorporated a-C:H (a-C:H:Si), and hydrogenated amorphous silicon carbide (a-SiC:H) layers (from top to bottom). Each layer was deposited using a radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) method, and the surface free energy of each layer was controlled by the experimental parameters. Thereafter, the three-layer-coated stent was expanded and evaluated under a scanning electron microscope (SEM) in order to determine whether or not cracking or delamination had occurred. It can be seen from the SEM images that the occurrence of cracks or delamination was markedly suppressed even in the bent region of the stent after expansion, where the plastic deformation is highly localized when stents are expanded. This indicates that the method we applied in this work can serve as one approach to overcoming the limitation described above.