Identification and Characterization of D‐Succinylase,and a Proposed Enzymatic Method for D‐Amino Acid Synthesis

Chiral amino acids are important intermediates for the pharmaceutical industry. We have developed a novel one‐pot enzymatic method for D ‐amino acid synthesis by the dynamic kinetic resolution of N‐succinyl‐dl ‐amino acids using D ‐succinylase (DSA) and N‐succinylamino acid racemase (NSAR, EC 4.2.1.113). The DSA from Cupriavidus sp. P4‐10‐C, which hydrolyzes N‐succinyl‐D ‐amino acids enantioselectively to their corresponding D ‐amino acids, was identified for the first time by screening soil microorganisms. Subsequently, the DSA gene was cloned and overexpressed in Escherichia coli. DSA was shown to comprise two subunits with molecular masses of 26 kDa and 60 kDa. Additionally, the NSAR gene from Geobacillus stearothermphilus NCA1503, which racemizes N‐succinylamino acids, was also cloned and overexpressed in E. coli. The highly purified DSA and NSAR prepared from each recombinant E. coli were characterized and used for D ‐amino acid synthesis. A one‐pot enzymatic method converted 100 mM N‐succinyl‐dl ‐phenylalanine to D ‐phenylalanine in 91.1% conversion with 86.7% ee. This novel enzymatic method may be useful for the industrial production of many D ‐amino acids.

     

An innovative modularity of heat circulation for fractional distillation

A novel modularity of heat circulation for distillation process, which reduces the energy consumption, is proposed. By incorporating compressors and heat exchangers, the heat of the distillate is recuperated and exchanged with the heat of the feed streams. The proposed technology achieves the reduction in the required energy more than 75% as compared with a benchmark process which uses external heat source for heating. This shows the proposed modularity of heat circulation for distillation process is very promising technology to drastically reduce energy demand for distillation.     

Anticorrosive behavior of hydroxyapatite as an environmentally friendly pigment

From the point of view of waste recycling, hydroxyapatite (HAp) can be synthesized using the waste sludge from semiconductor process. The possibility of using HAp as an anticorrosive pigment was investigated. The water absorption of coating pigmented with anticorrosive pigment, HAp, red lead (RL) and zinc potassium chromate (ZPC), and the corrosion at interface between coating and substrate were monitored using AC impedance technique. The amount of absorbed water decreased in the order of ZPC- > HAp- > RL-pigmented > unpigmented film. However, the water absorbed into HAp- or ZPC-pigmented film seems to be beneficial to anticorrosive function. The anticorrosive performance of HAp is superior or at least comparable to those of ZPC and RL, which have been known as representative anticorrosive pigments. It seems that the anticorrosive properties of HAp is mainly achieved by passivating the substrate, namely the soluble component of HAp reacts with Fe to form iron phosphate in the presence of water.     

In Situ Observation of Wear Process Before and During Scuffing in Sliding Contact

In this study, a direct observation of a point contact area was conducted to understand the scuffing phenomenon. The contact area was produced between a rotating sapphire disc and a stationary steel ball and it was lubricated using n-hexadecane. The image detected by a colour digital CCD camera, load, and friction were synchronously recorded by a computer during the test. It was found that wear debris produced in the contact area played an important role in the wear process, which includes running-in and scuffing. In the test, debris particles accumulated in the inlet zone, and some particles entered the contact area to cause abrasive wear of the ball surface, even in the light-load stages. During the running-in process, the abrasive wear by debris particles changed the conformity between the sliding surfaces. In the high-load stage, just before the occurrence of scuffing, the whole contact area was flattened at once. When scuffing occurred, the contact area suddenly expanded. The conformity of the contact area was dramatically changed during its expansion. The flattening of the whole contact area and dramatic expansion with changing the conformity seemed to play important roles in scuffing.     

Development of spectroscopic transmission-type four detector polarimeter

We have developed a spectroscopic transmission-type four detector polarimeter (T-FDP). It consists of a detector head and a multichannel spectrometer equipped with a two-dimensional CCD detector. Inside the T-FDP, three cubic beam splitters are aligned in a straight line and they are rotated relative to each other. From the responses of the spectroscopic T-FDP to five inputs with known polarization states it is possible to determine the characteristic matrices of the T-FDP at various wavelengths. The trajectories of the experimentally measured polarization states on the Poincaré sphere agree well with theoretical predictions. These results demonstrate the feasibility of using the T-FDP for spectroscopic ellipsometry.     

Acute non-cancer mortality excess after polychlorinated biphenyls and polychlorinated dibenzofurans mixed exposure from contaminated rice oil: Yusho

In Japan in 1968, rice-oil contaminated by polychlorinated biphenyls and polychlorinated dibenzofurans caused severe food poisoning, termed “Yusho” (oil disease). Several previous studies attempted to evaluate the effects targeting officially-certified Yusho patients. However, these studies have several limitations such as the left-truncated nature of the registry or residual confounding arising from the referent population selection. We thus conducted an area-based standardized mortality ratios (SMRs) study using vital statistics. A severely affected area (Tamanoura area) was adopted as the exposure group, with a reference population from Nagasaki prefecture in Kyushu, which included the Tamanoura. A large number of residents in Tamanoura were exposed to the rice-oil (28% of all the certified cases as of 2009). We estimated SMRs of non-cancer and cancer diseases for the years 1968-2002. Shortly after the exposure, SMRs of all causes, diabetes mellitus, cardiovascular disease, pneumonia/bronchitis, and bronchus/lung cancer were elevated. In particular, SMRs of heart disease were 1.97 [95% confidence intervals (CI): 1.09-3.56] in 1968, 2.05 (95% CI: 1.16-3.60) in 1969, and 1.89 (95% CI: 1.05-3.41) in 1975. However, we did not observe clear increase in SMRs more than 10 years after the exposure. This study provides further evidence in Yusho, especially on acute effects on non-cancer mortality.     

Three-dimensional organization of collagen fibrils during corneal stromal wound healing after excimer laser keratectomy

PURPOSE: To investigate the structural changes in corneal stromal collagen fibrils after excimer laser keratectomy in relation to the degree of corneal haze. SETTING: University of Tokyo Hospital, Tokyo, Japan. METHODS: Corneal haze was quantitatively measured by analyzing the light scattering in Scheimpflug images of the corneas of white rabbits after excimer laser keratectomy. Collagen fibril structure was examined using scanning electron microscopy after chemical digestion with sodium hydroxide solution; the same specimens were examined by transmission electron microscopy after re-embedding. RESULTS: Corneal haze reached a peak 4 weeks after excimer laser keratectomy and then gradually decreased. The collagen fibrils of the normal cornea were regularly arranged parallel to the surface of the cornea, with small interfibrillar distances. After excimer laser keratectomy, the arrangement was highly disordered, with increased interfibrillar distances. These structural changes were most prominent 4 weeks after excimer laser keratectomy. CONCLUSION: The structural changes in the collagen fibrils of the corneal stroma, especially the increase in interfibrillar distances and the disordered arrangement, were associated with corneal haze after excimer laser keratectomy.     

A cautious scheduler for multistep transactions

Given a classC of serializable schedules, a cautiousC-scheduler is an on-line transaction scheduler that outputs schedules in classC and never resorts to rollbacks. Such a scheduler grants the current request if and only if the partial schedule it has granted so far, followed by the current request, can be extended to a schedule inC. A suitable extension is searched among the set of all possible sequences of the pending steps, which are predeclared by the transactions whose first requests have already arrived. If the partial schedule cannot be extended to a schedule inC, then the current request is delayed. An efficient cautiousCPSR-scheduler has been proposed by Casanova and Bernstein. This paper discusses cautiousWRW-scheduling, whereWRW is the largest polynomially recognizable subclass of serializable schedules currently known. Since cautiousWRW-scheduling is, in general, NP-complete as shown in this paper, we introduce, a subclass (namedWRW ^#) ofWRW and discuss an efficient cautiousWRW ^#-scheduler. We also show that the fixed point set of the cautiousWRW ^#-scheduler properly containsCPSR. Therefore, ourWRW ^#-scheduler allows more concurrency than anyCPSR- scheduler.     

Preparation and characterization of the carbonized material of phenol-formaldehyde resin with addition of various organic substances

We prepared carbonized materials of phenol-formaldehyde resins (PF) synthesized with the addition of organic substances such as ethylene glycol (EG), 1,6-hexanediol (1,6HD), polyethylene glycol (PEG), etc. We investigated the influence of the carbonization temperature, the organic additive species, and the additive ratio in synthesizing the PF resins on the pore structure of the carbonized PFs. Variation in the length of the added organic substance caused differences in the pore sizes of the carbonized PFs; when the length was short, the pore size of the carbonized PF became gradually smaller with increasing carbonization temperature, but when the length was long, the pore size gradually increased with increasing carbonization temperature. The difference in the additive organic species gave different pore sizes in the carbonized PFs such that the longer the length of the organic additive the greater the pore size in the carbonized PF. The additive ratio of EG did not give a large change in the pore size of the carbonized PF, but the variance in the average pore sizes were sharper than that of the carbonized PF without any additives. On the other hand, the pore sizes of the carbonized PFs with a high additive ratio of PEG20K were greater, and the carbonized PFs had mesopores. The BET surface area of the carbonized PFs with a 50% additive ratio of PEG20K was about 500 m²/g.