Recovery of serum proteins using cellulosic affinity membrane modified by immobilization of CU2+ ion

An affinity membrane was prepared from a porous cellulose membrane, and adsorption and recovery of serum proteins were investigated from the viewpoint that affinity membranes are efficacious against separation and purification of biomaterials. Into the cellulose membrane, iminodiacetate (IDA) group that acts as a ligand to metal ions was introduced (Cell–IDA membrane), and then Cu²⁺ ion was immobilized (Cell–IDA–Cu membrane). Bovine serum albumin (BSA) and γ-globulin (BγG), which are the major proteins in blood, were adopted as model proteins to be separated. The Cell–IDA–Cu membrane had large adsorption capacity for these proteins despite the low degree of modification. The amounts of proteins adsorbed on the Cell–IDA–Cu membrane increased with increasing pH, and BγG was adsorbed more than BSA. High protein recoveries from the Cell–IDA–Cu membrane were obtained. The separation of these proteins was also conducted under the optimum conditions of adsorption and recovery, and BγG was concentrated more than BSA although the initial concentration of BγG was lower than that of BSA. © 1996 John Wiley & Sons, Inc.     

Electrochemical Molecular Conversion of α-Keto Acid to Amino Acid at a Low Overpotential Using a Nanoporous Gold Catalyst

A nanoporous gold (NPG) electrode prepared through a facile anodization technique was employed in the electrochemical reductive amination of biomass-derivable α-keto acids in the presence of a nitrogen source to produce the corresponding amino acids. NPG showed a clear reductive current in the presence of α-keto acid and NH₂OH, and the electrolysis experiments confirmed the production of L-amino acid. A reductive voltammetric signal at the NPG electrode appeared at a more positive potential by 0.18–0.79 V, compared with those at the planar-gold electrode without anodization and other previously reported electrode systems, indicating the high activity of the prepared nanostructure for the electrochemical reaction. Maximum Faradaic efficiencies (FEs) of 74–93% in the reductive molecular conversion to amino acids of Ala, Asp, Glu, Gly, and Leu were obtained under the optimized conditions. The FE values were strongly dependent on the applied potential in the electrolysis, suggesting that the hydrogen evolution reaction at the electrode surface was more significant as the applied potential became more negative. The effect of potential at the NPG was lower than that at the planar-gold electrode. These results indicate that nanostructurization decreases the overpotential for the electrochemical reductive amination, resulting in high FE.     

Organocatalytic Enantioselective Decarboxylative Addition of Malonic Acids Half Thioesters to Isatins

The organocatalytic enantioselective decarboxylative addition of malonic acids half thioesters to isatins using a squaramide catalyst afforded the products with high enantioselectivity. These products are key intermediates in the synthesis of 3‐substituted 3‐hydroxy‐2‐oxindole derivatives. The first enantioselective synthesis of (−)‐flustraminol B has been accomplished.     

Algorithm improvement and validation of National Institute for Environmental Studies ozone differential absorption lidar at the Tsukuba Network for Detection of Stratospheric Change complementary station

Recently, a data processing and retrieval algorithm (version 2) for ozone, aerosol, and temperature lidar measurements was developed for an ozone lidar system at the National Institute for Environmental Studies (NIES) in Tsukuba (36 degrees N,140 degrees E), Japan. A method for obtaining the aerosol boundary altitude and the aerosol extinction-to-backscatter ratio in the version 2 algorithm enables a more accurate determination of the vertical profiles of aerosols and a more accurate correction of the systematic errors caused by aerosols in the vertical profile of ozone. Improvements in signal processing are incorporated for the correction of systematic errors such as the signal-induced noise and the dead-time effect. The mean vertical ozone profiles of the NIES ozone lidar were compared with those of the Stratospheric Aerosol and Gas Experiment II (SAGE II); they agreed well within a 5% relative difference in the 20-40 km altitude range and within 10% up to 45 km. The long-term variations in the NIES ozone lidar also showed good coincidence with the ozonesonde and SAGE II at 20, 25, 30, and 35 km. The temperatures retrieved from the NIES ozone lidar and those given by the National Center for Environmental Prediction agreed within 7 K in the 35-50 km range.     

Real-time measurement of mixing ratio of refrigerant/refrigeration oil mixture

The mixing of refrigeration oil with refrigerant in a refrigeration cycle has great influence on cycle performance. A sampling method is the most general way to measure the mixing ratio of refrigerant and refrigeration oil. Since the sampling method is time-consuming and reduces the amount of refrigerant and oil in the cycle, a real-time measurement is desirable. In this study, a refractive index measurement was applied to measure the mixing ratio of refrigerant/oil mixture. A laser displacement sensor was used to detect any change in optical path which results from changes of the refractive index of refrigerant/oil mixture. For the practical application of real-time measurement of the oil circulation ratio (OCR) in the refrigeration cycle, a correlation between the refractive index and the mixing ratio was developed. In addition, the changes of the refractive index in a range of a few percentages of the oil concentration and under subcooled conditions were measured. Finally, a transient measurement of the OCR in a practically operating refrigeration cycle was carried out successfully.     

Frame shuffling: a novel method for in vitro protein evolution

We describe 'frame shuffling', a novel method for preparing artificial protein libraries. With this method, a Y-family DNA polymerase known to introduce frame shift mutations at high rates is utilized to scramble the reading frames of a parental gene. The resultant progeny produce mutant proteins having segmental sequence changes. Such frame-shuffled mutant proteins exhibit physicochemical properties that differ from those of proteins obtained using conventional mutagenesis.     

Amorphous nanosilicas induce consumptive coagulopathy after systemic exposure

We previously reported that well-dispersed amorphous nanosilicas with particle size 70 nm (nSP70) penetrate skin and produce systemic exposure after topical application. These findings underscore the need to examine biological effects after systemic exposure to nanosilicas. The present study was designed to examine the biological effects. BALB/c mice were intravenously injected with amorphous nanosilicas of sizes 70, 100, 300, 1000 nm and then assessed for survival, blood biochemistry, and coagulation. As a result, injection of nSP70 caused fatal toxicity, liver damage, and platelet depletion, suggesting that nSP70 caused consumptive coagulopathy. Additionally, nSP70 exerts procoagulant activity in vitro associated with an increase in specific surface area, which increases as diameter reduces. In contrast, nSP70-mediated procoagulant activity was absent in factor XII-deficient plasma. Collectively, we revealed that interaction between nSP70 and intrinsic coagulation factors such as factor XII, were deeply related to nSP70-induced harmful effects. In other words, it is suggested that if interaction between nSP70 and coagulation factors can be suppressed, nSP70-induced harmful effects may be avoided. These results would provide useful information for ensuring the safety of nanomaterials (NMs) and open new frontiers in biological fields by the use of NMs.     

Effect of hydration on electrical conductivity of DNA duplex: Green’s function study combined with DFT

The electrical conductivity of DNA duplex is affected by many factors such as DNA base sequence, hydration of DNA duplex, connecting configuration between DNA duplex and electrodes, thermal fluctuation of DNA duplex structure. We here investigate the electrical conducting properties of DNA duplexes sandwiched between Au electrodes by molecular simulations using nonequilibrium Green’s function method coupled with density functional theory. The results reveal the dependence of electrical conductivity on DNA base sequence as well as hydration, which are in qualitative agreement with experiment. The present results indicate the important role played by hydrating water molecules in the electrical conductivity through DNA duplexes.     

Absolute distance measurement of optically rough objects using asynchronous-optical-sampling terahertz impulse ranging

We report on a real-time terahertz (THz) impulse ranging (IPR) system based on a combination of time-of-flight measurement of pulsed THz radiation and the asynchronous-optical-sampling (ASOPS) technique. The insensitivity of THz radiation to optical scattering enables the detection of various objects having optically rough surfaces. The temporal magnification capability unique to ASOPS achieves precise distance measurements of a stationary target at an accuracy of -551 μm and a resolution of 113 μm. Furthermore, ASOPS THz IPR is effectively applied to real-time distance measurements of a moving target at a scan rate of 10 Hz. Finally, we demonstrate the application of ASOPS THz IPR to a shape measurement of an optically rough surface and a thickness measurement of a paint film, showing the promise of further expanding the application scope of ASOPS THz IPR. The reported method will become a powerful tool for nondestructive inspection of large-scale structures.