Four-base codon-mediated incorporation of non-natural amino acids into proteins in a eukaryotic cell-free translation system

Various four-base codons have been shown to work for the introduction of non-natural amino acids into proteins in an Escherichia coli cell-free translation system. Here, a four-base codon-mediated non-natural mutagenesis was applied to a eukaryotic rabbit reticulocyte cell-free translation system. Mutated streptavidin mRNAs containing four-base codons were prepared and added to a rabbit reticulocyte lysate in the presence of tRNAs that were aminoacylated with a non-natural amino acid and had the corresponding four-base anticodons. A Western blot analysis of translation products indicated that the four-base codons CGGU, CGCU, CCCU, CUCU, CUAU, and GGGU were efficiently decoded by the aminoacyl-tRNAs having the corresponding four-base anticodons. In contrast, the four-base codons AGGU, AGAU, CGAU, UUGU, UCGU, and ACGU were not decoded. The stop codon-derived four-base codons UAGU, UAAU, and UGAU were found to be inefficient, whereas the amber codon UAG and opal codon UGA were efficient for the incorporation of non-natural amino acids. The application of the expanded genetic code in a eukaryotic cell-free system opens the possibility of a four-base codon-mediated incorporation of non-natural amino acids into proteins in living eukaryotic cells.     

Effect of Seeding on Metal Ion Recovery from Wastewater by Reactive Crystallization of Metal Carbonates

Reactive crystallization for separation and recovery of divalent metal ions from wastewater using a semi‐batch crystallizer has been developed. In this process, metal carbonates are produced by reacting metal sulfate solution with sodium carbonate solution. Nickel and copper ions are crystallized under particular initial pH conditions but the product shapes are not regular. Consequently, sphere seeds have been used as nucleus‐generating agents and their growth mechanism has been examined. When providing a particular amount of seeds before crystallization, metal substances piled up on the surface of the seeds, maintaining the form sphere, and the production of fines was restricted. The metal removal rate through reactive crystallization was ～99.9 % on average. This operation proved to be suitable for application in industrial wastewater treatment and for recycling of metal materials.     

Phase transition of thermosensitive amphiphilic cellulose esters bearing olig(oxyethylene)s

Summary A series of cellulose esters bearing olig(oxyethylene)s with different degree of substitution (DS) and different length of the oxyethylene chain were synthesized by a homogeneous reaction of cellulose with corresponding monofunctional acid chloride in a 10% LiCl-dimethyl acetoamide (DMAc) solution. The effect of total DS value on the solubility of the derivatives in aqueous solution was investigated. It was found that the lower limit DS value for both water-soluble and amphiphilic derivatives decreases with increasing length of oxyethylene chains. The amphiphilic derivatives, which are soluble in both water and chloroform, precipitate out of aqueous solution on heating without gel forming, such a phase transition behavior was studied in terms of DS value, length of oxyethylene and concentration. The precipitation temperature (T_p) of the amphiphilic derivatives is range from 54°C to 96°C. It decreases with increasing the total DS value, and increases with an increase in the length of oxyethylene chains. The T_p value of the derivatives was found to be almost independent in the concentration range of 1–15 wt %, however the T_p value increases sharply with decreasing polymer concentration when the concentration is lower than 1 wt%. Received: 29 August 2000/Revised version: 16 October 2000/Accepted: 31 October 2000     

日本建筑用密封材料的现状和发展趋势

对日本建筑用密封材料的发展趋势、应用领域、材料标准以及设计施工规范等内容进行了阐述。     

An integrated numerical simulator for thermal performance assessments of firefighters’ protective clothing

Research and development of firefighters’ protective clothing relies on a large number of fire disaster experiments in order to assess the thermal performance. It would be substantially advantageous to substitute a virtual numerical experiment for a real one in terms of time, cost and safety. The present article reports the development of an integrated numerical simulator that makes possible the estimation of burn injuries originating from fire disasters. In the simulator, a general-purpose computational fluid dynamics program computes the fluid flow and heat transfer in an in situ fire event, while a one-dimensional program calculates the radiative–conductive heat transfer through the clothing and human skin. A data interface combines the two simulations by loose coupling so as to give the real-time burn injury progress output. The predicted surface heat fluxes and burn degrees agree with experimental measurements reasonably well. Possible numerical error sources are discussed that call for potential improvements in the future.     

Negative giant surface potential of vacuum-evaporated tris(7-propyl-8-hydroxyquinolinolato) aluminum(III) [Al(7-Prq)3] film

Negative giant surface potential was realized in a vacuum-evaporated film of tris(7-propyl-8-hydroxyquinolinolato) aluminum(III) [Al(7-Prq)₃]. Electroabsorption response of the film presented an inverted polarity to that of tris(8-hydroxyquinolinolato) aluminum (Alq₃), suggesting opposite noncentrosymmetry of molecular orientation. Asymmetric dice model with molecular geometric effect has been proposed, and propyl substitution at 7 position of the ligands was indicated to affects the molecular posture on the surface to invert the polarity of noncentrosymmetry. Our results opened a new possibility of controlling molecular orientation in a film for device applications.     

Effect of annealing on the electrochemical properties of ramsdellite-type lithium titanium oxide

Lithium titanium oxide (LTO) with a ramsdellite structure is an advantageous anode for lithium ion secondary batteries, because of its positive potential, which is beneficial for safety reasons. In addition, compared with other titanate anodes, it has a superior theoretical capacity of 321 mA h g⁻¹, which is close to the capacity of a practical carbonaceous anode. Our study showed that this ramsdellite-type LTO had a high discharge capacity that is stable at 250 mA h g⁻¹ at a current density of 1 mA cm⁻². However, this high capacity is only achieved by employing as-synthesized ramsdellite LTO powder. When the same powder was stored and the same evaluation was carried out, the resulting capacity was 200 mA h g⁻¹, which is lower than the capacity of as-synthesized powder. An annealing applied to the ramsdellite LTO powder appeared to restore the capacity loss after storage. Annealing at 250 °C for 5 h produced the best performance, which was even better than that obtained using the as-synthesized ramsdellite LTO powder. Moreover, we investigated the surface property of ramsdellite LTO and found that the presence of a carbon derivative is apparently responsible for blocking the Li ions insertion/extraction, and thus reducing the capacity.     

Reusability, Durability and Treatability of Palladium Catalyst on a Semiconductor Plate: Comparison with Commercially Available Solid-Supported Palladium Catalysts

A palladium catalyst supported on a semiconductor plate underwent the Heck reaction effectively to afford a coupling product. The catalytic plate was easily recovered from the reaction mixture with tweezers and reused several times without any special treatment. Comparison of reusability, durability, and treatability of seven kinds of commercially available solid-supported palladium catalysts and the semiconductor-supported catalyst plate was studied.     

Hand-eye system with three-dimensional vision and microgripper for handling flexible wire

A three-dimensional hand-eye system has been specially developed for handling, forming, and inserting flexible wires in electronic assemblies. The system consists of a vision system capable of measuring three-dimensional positions and a gripper capable of microforce control. The hand-eye system performs its tasks based on visual and force sensor data.The vision system uses a camera, a multiplanar laser light projector, and a video-rate image processor to measure the three-dimensional position of a flexible wire on a complex background. The projector consists of multiplanar light beams and a single-planar light beam and is robot-mountable. The single-planar light is used to simplify the matching of the multiplanar light beams and projection images. This is one of the most important features of our method. The measurement time is within 1.2 s for 20 positions on the wire, which is less than one robot cycle. The measurement accuracy is better than 0.2 mm in the plane for a 100×100 mm scene and is better than 1 mm perpendicular to the plane for a depth of 500 mm.The microgripper has 3-axis sensors capable of detecting three types of forces: grasping, pulling, and pushing. The dynamic range of the grasping force is 0.005 to 0.6 N, enabling high-resolution control. Two piezoelectric actuators are used in the microgripper fingers and a 3-mm stroke is achieved by amplifying the actuator's displacement using a two-stage lever.This system has been used for wire handling in magnetic disk slider manufacture, which is a difficult and delicate task. Measurement, grasping, and upper-stage insertion had a 100 percent success rate using autorecovery, making the hand-eye system feasible. This paper discusses design concepts, the range measurement principle, the system itself, and wire-handling applications.