Construction of a plasmid carrying both CTP synthetase and a fused gene formed from cholinephosphate cytidylyltransferase and choline kinase genes and its application to industrial CDP-choline production: enzymatic production of CDP-choline from orotic acid (Part II)

A new method for enzymatic production of cytidine diphosphate choline (CDP-choline) from orotic acid and choline chloride was developed. To establish an industrial manufacturing process, we constructed a plasmid, pCKG55, which simultaneously expressed in Escherichia coli the three following enzymes; CTP synthetase (encoded by the pyrG gene from E. coli), cholinephosphate cytidylyltransferase (encoded by the CCT gene from Saccharomyces cerevisiae), and choline kinase (encoded by the CKI gene from S. cerevisiae). CCT and CKI genes on pCKG55 were designed to be expressed as a single CCT/CKI fused protein. This CCT/CKI fused protein retained both activities and the thermal stability of its cholinephosphate cytidylyltransferase activity was nearly the same as the native CCT enzyme. Corynebacterium ammoniagenes KY13505 and E. coli MM294/pCKG55 were cultured in 5-liter jar fermentor independently. Equal volumes of each broth were mixed in a 2-liter jar fermentor, and then the enzymatic reaction was done using 47 mM orotic acid and 60 mM choline chloride as substrates. After 23 h of the reaction at 32 degrees C, 21.5 mM (11 g/liter) of CDP-choline was accumulated.     

Characterization of alternative plasticizers in poly(vinyl chloride) sheets for blood containers

This study aimed to optimize the ratio of dioctyl 4‐cyclohexene‐1,2‐dicarboxylate (DOTH) and di‐isononyl‐cyclohexane‐1,2‐dicarboxylate (DINCH^®) for use as plasticizers in poly(vinyl chloride) (PVC) sheets. We also evaluated the biological safety of DOTH for its potential to be part of a safe PVC‐based blood container. The suppression of hemolysis in mannitol‐adenine‐phosphate / red cell concentrates (MAP/RCC) with DOTH/(DINCH^®‐PVC) sheets and the elution of plasticizers from the sheets increased with higher DOTH compositions. The properties of the PVC sheet containing DOTH and DINCH^® in the ratio of 25:33 parts against PVC 100 parts as a weight were almost identical to the PVC sheet made of di(2‐ethylhexyl) phthalate. From a subchronic toxicity test, DOTH did not show any adverse effects on all organs, including the testes, epididymis, liver, and kidneys. The no‐observed‐adverse‐effect level was 300 mg/kg body weight/day in a rat. These results suggest that DOTH/DINCH^® (25:33) is a promising candidate for the replacement of di(2‐ethylhexyl) phthalate in blood containers. J. VINYL ADDIT. TECHNOL., 22:520–528, 2016. © 2015 Society of Plastics Engineers     

Formation and Characterization of Ce3ZrO8 Prepared by the Hydrazine Method

A compound denoted as (Ce_0.75Zr_0.25)O₂ (Ce, ZrO₈) is formed near room temperature from cerium and zirconium nitrates using hydrazine monohydrate. It has a cubic unit cell with a = 0.5342 nm. Characterization of powders heated to various temperatures at 10°C/min demonstrates that the specific surface area does not decrease below 20 mVg until >1000°C.     

The role of microstructure on pesting during oxidation of MoSi2 and Mo(Si,Al)2 at 773 K

The pesting behavior of MoSi₂ and Mo(Si,Al)₂ has been examined in air at 773 K to clarify the origin and mechanism of pesting phenomena and the effect of aluminum on pesting phenomena. The initial cracks play a much more important role than the grain boundaries and the initial oxide layer in pesting. Mo and Si oxidize to amorphous Mo-Si-O simultaneously with about a 200% volume expansion. Therefore, large stress appears at the cracktips and induce many new cracks. MoO₃ vaporizes from the Mo-Si-O layer on the external surface and crack surfaces causing the oxides in the initial cracks to become porous. Oxygen has a short-circuit path to enter the sample in the cracks. Therefore, the partial pressure of oxygen is sufficiently high to allow oxidation of Mo in the materials. The platelet-like MoO₃ grows on the external surface and also in the cracks. Finally, the sample distintegrates into powder. Pesting of Mo(Si,Al)₂ occurs in the same way, however, its rate is much lower than that of MoSi₂. The role of Al is to decrease the initial crack density of the samples from the melt. Other effects of Al might be to decrease the oxygen flux toward the oxide-intermetallic interface and to increase the plasticity of the amorphous oxide being formed in the cracks.     

Precision dilatometer analysis of neutron-irradiated nuclear graphite recovery process up to 1673 K

Specimens of two kinds of isotropic nuclear graphite, IG-110U and ETP-10, were neutron-irradiated at fluence of 1.92 × 10²⁴ n/m² (E > 1.0 MeV) at 473 K. The recoveries of the macroscopic lengths of these specimens during isothermal and isochronal annealing at temperatures of up to 1673 K were investigated in a step-wise manner by using a precision dilatometer. The macroscopic lengths after isochronal annealing for 6 h at each temperature decreased gradually as the temperature was increased to 1673 K. The recovery trends of the c-axis and a-axis lattice parameters differed from one another, and from the macroscopic length recovery trends. For the IG-110U specimen, the activation energies (E_a) of macroscopic volume recovery corresponding to annealing at 523–773, 773–923, 923–1073, and 1073–1173 K were found to be 0.15, 0.34, 0.73, and 2.59 eV, respectively. For the ETP-10 specimen, the E_a corresponding to 523–923, 923–1223, and 1223–1373 K were determined to be 0.15, 0.46, and 2.19 eV, respectively. These results indicate that both graphite specimens underwent three or four stages of macroscopic length recovery between 523 K and the annealing temperatures at which their initial lengths were recovered. It is suggested that during the first stage recovery proceeded via the migration of single interstitials along the basal plane and the resulting V-I recombination. In the middle stages, recovery occurred due to the migration of interstitial groups such as C₂ along the basal plane, while in the last stage, it proceeded via through-layer migration of interstitials or migration of single vacancies.     

Measurement of the isotopic abundance of boron-10 by inductively coupled plasma-quadrupole mass spectrometry

This article describes the method for measuring the isotopic abundance of ¹⁰B in nuclear grade boron carbide using inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS). The results of investigation revealed that both the integration time and the dwell time have a major influence on the reproducibility of ICP-QMS measurements. As a result of optimization of the measurement conditions, reproducibility below 0.2% relative standard deviation (RSD) (0.17% RSD maximum) was achieved. In addition, the measured value of the isotopic abundance of ¹⁰B for each sample well agreed with the values measured by the TIMS. Thus, the method described in the present investigation was very effective in the analysis of isotopic abundance of ¹⁰B in B₄C or H₃BO₃. The results of this study suggest that ICP-QMS could be applied to the precise analysis of the isotopic abundance of ¹⁰B required in the field of nuclear applications.     

Environmental protection: researches in National Institute of Radiological Sciences

Some studies for radiological protection of the environment have been made at the National Institute of Radiological Sciences (NIRS). Transfer of radionuclides and related elements has been investigated for dose estimation of non-human biota. A parameter database and radionuclide transfer models have been also developed for the Japanese environments. Dose (rate)-effect relationships for survival, growth and reproduction have been investigated in conifers, Arabidopsis, fungi, earthworms, springtails, algae, duckweeds, daphnia and medaka. Also genome-wide gene expression analysis has been carried out by high coverage expression profiling (HiCEP). Effects on aquatic microbial communities have been studied in experimental ecosystem models, i.e., microcosms. Some effects were detected at a dose rate of 1 Gy day(-1) and were likely to arise from interspecies interactions. The results obtained at NIRS have been used in development of frameworks for environmental protection by some international bodies, and will contribute to environmental protection in Japan and other Asian countries.     

Synthesis and hydrophilic property of polypropylene-graft-poly(polyethylene glycol-methacrylate) (PP-g-P(PEGMA))

Polypropylene-graft-poly(polyethylene glycol-methacrylate) (PP-g-P(PEGMA)), which is a hydrophobic-hydrophilic graft copolymer, was synthesized by a combination of an atom transfer radical polymerization (ATRP) of PEGMA with brominated polypropylene (PP-Br), which was synthesized from PP-OH prepared by metallocene-catalyzed copolymerization. Its structure was confirmed by ¹H NMR and GPC analyses. Transmission electron microscope (TEM) micrographs of PP-g-P(PEGMA) revealed the nanometer level microphase-separation morphology between the PP segment and the P(PEGMA) segment. The obtained PP-g-P(PEGMA) showed water-absorbing property as well as thermostability.     

Influence of Acid Modification on Selective Phenol Hydrogenation Over Pd/Activated Carbon Catalysts

The influence of the acid treatment on cyclohexanone selectivity of phenol hydrogenation over Pd on active carbon was studied in liquid phase reaction and by temperature-programmed desorption. Acid treatment of activated carbon led to an increased cyclohexanone/cyclohexanol ratio. Acid modification of the carbon support enriched the electron density of Pd, and enhanced the desorption of the phenoxy species, which resulted in improved cyclohexanone selectivity in phenol hydrogenation.