Enhanced Material Assimilation in a Toroidal Plasma Using Mixed H_{2}+Ne Pellet Injection and Implications to ITER

The ablation and assimilation of cryogenic pure H_{2} and mixed H_{2}+Ne pellets, which are foreseen to be used by the ITER tokamak for mitigating thermal and electromagnetic loads of major disruptions, are observed by spatially and temporally resolved measurements. It is experimentally demonstrated that a small fraction (here ≈5%) of neon added to hydrogenic pellets enhances the core density assimilation with reduced outward transport for the low magnetic-field side injection. This is consistent with theoretical expectations that line radiation increased by doped neon in dense plasmoids suppresses the plasmoid pressure and reduces the E[over →]×B[over →] transport of the ablated material.

Biocatalytic synthesis and evaluation of antioxidant and antibacterial activities of hydroxyequols

Hydroxyequols are promising analogues of the biologically active flavonoid, equol. We recently found that the flavin-dependent monooxygenase HpaB_ro-3 of Rhodococcus opacus regioselectively synthesizes 3'-hydroxyequol from equol, whereas HpaB_pl-1 of Photorhabdus luminescens synthesizes 6-hydroxyequol. In this study, we investigated the cascade synthesis of a dihydroxyequol compound from equol using these two enzymes. When Escherichia coli cells expressing HpaB_ro-3 and cells expressing HpaB_pl-1 were simultaneously incubated with equol, the cells efficiently synthesized 6,3'-dihydroxyequol (8.7 mM, 2.4 g/L) via 3'- and 6-hydroxyequols in one pot. The antioxidant activity of the equol derivatives increased with an increase in the number of hydroxyl groups on the equol scaffold. 6,3'-Dihydroxyequol exhibited potent antioxidant activity. In addition, 6-hydroxyequol significantly inhibited the growth of E. coli. Cell survival studies suggested that 6-hydroxyequol is a bactericidal rather than bacteriostatic compound. To our knowledge, this is the first report describing the antibacterial activity of hydroxyequols.

A comprehensive atlas of Aggrecan, Versican, Neurocan and Phosphacan expression across time in wildtype retina and in retinal degeneration

As photoreceptor cells die during retinal degeneration, the surrounding microenvironment undergoes significant changes that are increasingly recognized to play a prominent role in determining the efficacy of therapeutic interventions. Chondroitin Sulphate Proteoglycans (CSPGs) are a major component of the extracellular matrix that have been shown to inhibit neuronal regrowth and regeneration in the brain and spinal cord, but comparatively little is known about their expression in retinal degeneration. Here we provide a comprehensive atlas of the expression patterns of four individual CSPGs in three models of inherited retinal degeneration and wildtype mice. In wildtype mice, Aggrecan presented a biphasic expression, while Neurocan and Phosphacan expression declined dramatically with time and Versican expression remained broadly constant. In degeneration, Aggrecan expression increased markedly in Aipl1-/- and Pde6brd1/rd1, while Versican showed regional increases in the periphery of Rho-/- mice. Conversely, Neurocan and Phosphacan broadly decrease with time in all models. Our data reveal significant heterogeneity in the expression of individual CSPGs. Moreover, there are striking differences in the expression patterns of specific CSPGs in the diseased retina, compared with those reported following injury elsewhere in the CNS. Better understanding of the distinct distributions of individual CSPGs will contribute to creating more permissive microenvironments for neuro-regeneration and repair.

Monooxygenase-catalyzed regioselective hydroxylation for the synthesis of hydroxyequols

A one-step product-selective approach for synthesizing hydroxyequols from equol using oxidation biocatalysts was developed.

Improved ECG Signal Analysis Using Wavelet and Feature Extraction

Objectives : Automatic detection of arrhythmias is important for diagnosis of heart problems. However, in ECG signals, there is significant variation of waveforms in both normal and abnormal beats. It is this phenomenon, which makes it difficult to analyse ECG signals. The aim of developing methodology is to distinguish between normal beats and abnormal beats in an ECG signal.

Methods : ECG signals were first decomposed using wavelet transform. The feature vectors were then extracted from these decomposed signals as normalised energy and entropy. To improve the classification of the feature vectors of normal and abnormal beats, the normal beats which occur before and after the abnormal beats were eliminated from the group of normal beats.

Results : With our proposed methods, the normal beats and abnormal beats formed different clusters of vector points. By eliminating normal beats which occur before and after the abnormal beats, the clusters of different types of beats showed more apparent separation.

Conclusions : The combination of wavelet decomposition and the classification using feature vectors of the beats in ECG signals separate abnormal beats from normal beats. The elimination of the normal beats which occur before and after the abnormal beats succeeded in minimising the size of normal beats cluster.

Impact of surgical margins on survival of 37 dogs with massive hepatocellular carcinoma

AIMS

To compare the survival of dogs with completely resected massive hepatocellular carcinoma (HCC) with that of dogs in which HCC were incompletely excised.

METHODS

A retrospective cohort study was conducted. Dogs that underwent surgical excision of massive HCC between November 2006 and April 2015 were included. Dogs that died in the perioperative period or were lost to follow-up within 2 months after surgery were excluded. Data were collected from the medical records and a single pathologist examined all available histology slides to confirm the diagnosis of HCC. Surgical margins were defined as complete if no neoplastic cells were seen at the edge of excised tissues, based on original histopathology reports. Progression-free survival (PFS) and overall survival (OS) were compared between dogs with complete surgical margins (CM) and those with incomplete margins (IM) using a log-rank test.

RESULTS

Of the 37 dogs included in the study, 25 were allocated to the CM group and 12 to the IM group. Progressive local disease developed after surgery in three dogs in the CM group and seven dogs in the IM group. Three dogs in the CM group and five dogs in the IM group died due to tumour progression. Median PFS was longer for dogs in the CM group (1,000 (95% CI=562-1,438) days) compared to dogs in the IM group (521 (95% CI=243-799) days; p=0.007). OS was also longer for dogs in the CM group (>1,836 days) compared to those in the IM group (median 765 (95% CI=474-1,056) days; p=0.02).

CONCLUSIONS AND CLINICAL RELEVANCE

Compared with complete resection, incomplete resection decreased PFS and OS in dogs with massive HCC. Dogs with incompletely excised HCC should be closely monitored for local recurrence, although median OS was >2 years following incomplete excision. Further prospective studies are warranted to confirm these findings.

Exposure to an atomic bomb explosion is a risk factor for in-hospital death after esophagectomy to treat esophageal cancer

Esophagectomy, one of the most invasive of all gastrointestinal operations, is associated with a high frequency of postoperative complications and in-hospital mortality. The purpose of the present study was to determine whether exposure to the atomic bomb explosion at Hiroshima in 1945 might be a preoperative risk factor for in-hospital mortality after esophagectomy in esophageal cancer patients. We thus reviewed the outcomes of esophagectomy in 31 atomic bomb survivors with esophageal cancer and 96 controls (also with cancer but without atomic bomb exposure). We compared the incidences of postoperative complications and in-hospital mortality. Of the clinicopathological features studied, mean patient age was significantly higher in atomic bomb survivors than in controls. Of the postoperative complications noted, atomic bomb survivors experienced a longer mean period of endotracheal intubation and higher incidences of severe pulmonary complications, severe anastomotic leakage, and surgical site infection. The factors associated with in-hospital mortality were exposure to the atomic bomb explosion, pulmonary comorbidities, and electrocardiographic abnormalities. Multivariate analysis revealed that exposure to the atomic bomb explosion was an independent significant preoperative risk factor for in-hospital mortality. Exposure to the atomic bomb explosion is thus a preoperative risk factor for in-hospital death after esophagectomy to treat esophageal cancer.

Hydrogen-driven asymmetric reduction of hydroxyacetone to (R)-1,2-propanediol by Ralstonia eutropha transformant expressing alcohol dehydrogenase from Kluyveromyces lactis

BACKGROUND

Conversion of industrial processes to more nature-friendly modes is a crucial subject for achieving sustainable development. Utilization of hydrogen-oxidation reactions by hydrogenase as a driving force of bioprocess reaction can be an environmentally ideal method because the reaction creates no pollutants. We expressed NAD-dependent alcohol dehydrogenase from Kluyveromyces lactis in a hydrogen-oxidizing bacterium: Ralstonia eutropha. This is the first report of hydrogen-driven in vivo coupling reaction of the alcohol dehydrogenase and indigenous soluble NAD-reducing hydrogenase. Asymmetric reduction of hydroxyacetone to (R)-1,2-propanediol, which is a commercial building block for antibacterial agents, was performed using the transformant as the microbial cell catalyst.

RESULTS

The two enzymes coupled in vitro in vials without a marked decrease of reactivity during the 20 hr reaction because of the hydrogenase reaction, which generates no by-product that affects enzymes. Alcohol dehydrogenase was expressed functionally in R. eutropha in an activity level equivalent to that of indigenous NAD-reducing hydrogenase under the hydrogenase promoter. The hydrogen-driven in vivo coupling reaction proceeded only by the transformant cell without exogenous addition of a cofactor. The decrease of reaction velocity at higher concentration of hydroxyacetone was markedly reduced by application of an in vivo coupling system. Production of (R)-1,2-propanediol (99.8% e.e.) reached 67.7 g/l in 76 hr with almost a constant rate using a jar fermenter. The reaction velocity under 10% PH2 was almost equivalent to that under 100% hydrogen, indicating the availability of crude hydrogen gas from various sources. The in vivo coupling system enabled cell-recycling as catalysts.

CONCLUSIONS

Asymmetric reduction of hydroxyacetone by a coupling reaction of the two enzymes continued in both in vitro and in vivo systems in the presence of hydrogen. The in vivo reaction system using R. eutropha transformant expressing heterologous alcohol dehydrogenase showed advantages for practical usage relative to the in vitro coupling system. The results suggest a hopeful perspective of the hydrogen-driven bioprocess as an environmentally outstanding method to achieve industrial green innovation. Hydrogen-oxidizing bacteria can be useful hosts for the development of hydrogen-driven microbial cell factories.

Imaging spectroscopy diagnosis of internal electron temperature and density distributions of plasma cloud surrounding hydrogen pellet in the Large Helical Device

To investigate the behavior of hydrogen pellet ablation, a novel method of high-speed imaging spectroscopy has been used in the Large Helical Device (LHD) for identifying the internal distribution of the electron density and temperature of the plasma cloud surrounding the pellet. This spectroscopic system consists of a five-branch fiberscope and a fast camera, with each objective lens having a different narrow-band optical filter for the hydrogen Balmer lines and the background continuum radiation. The electron density and temperature in the plasma cloud are obtained, with a spatial resolution of about 6 mm and a temporal resolution of 5 × 10(-5) s, from the intensity ratio measured through these filters. To verify the imaging, the average electron density and temperature also have been measured from the total emission by using a photodiode, showing that both density and temperature increase with time during the pellet ablation. The electron density distribution ranging from 10(22) to 10(24) m(-3) and the temperature distribution around 1 eV have been observed via imaging. The electron density and temperature of a 0.1 m plasma cloud are distributed along the magnetic field lines and a significant electron pressure forms in the plasma cloud for typical experimental conditions of the LHD.

Prognostic significance of BAF57 expression in patients with endometrial carcinoma

This study was conducted to elucidate the prognostic significance of BAF57 in patients with endometrial carcinoma. We investigated the relationship between the immunohistochemical expression of BAF57 and various clinicopathological variables in 111 endometrial carcinomas. Both univariate and multivariate regression analyses were performed. The correlations between the BAF57 expression and the other variables including estrogen receptor (ER) and p53 were examined. The high nuclear BAF57 expression was detected in 42 (37.8%) endometrial carcinomas, and 69 (62.2%) endometrial carcinomas were defined as having low nuclear BAF57 expression. The BAF57 expression was significantly associated with the surgical stage, grade of the tumor, myometrial invasion, lympho-vascular space invasion (LVSI) and lymph node metastasis. The 10-year overall survival rates of patients with low and high BAF57 expression were 96.9% and 58.2%, respectively (p<0.001). A multivariate analysis identified BAF57 expression as an independent prognostic factor. The BAF57 expression was significantly correlated with p53 expression (r=0.312, P=0.001), but was not correlated with ER expression (r= -0.141, P=0.14). The high BAF57 expression is an independent marker of poor prognosis of the patients in endometrial carcinomas. The inhibition of BAF57 activity may be one of the candidates for endometrial cancer therapy, especially therapy for aggressive tumors showing overexpression of p53.

Design and performance of a punch mechanism based pellet injector for alternative injection in the large helical device

A low speed single barrel pellet injector, using a mechanical punch device has been developed for alternative injection in the large helical device. A pellet is injected by the combined operation of a mechanical punch and a pneumatic propellant system. The pellet shape is cylindrical, 3 mm in diameter and 3 mm in length. Using this technique the speed of the pellet can be controlled flexibly in the range of 100-450 m/s, and a higher speed can be feasible for a higher gas pressure. The injector is equipped with a guide tube selector to direct the pellet to different injection locations. Pellets are exposed to several curved parts with the curvature radii R(c) = 0.8 and 0.3 m when they are transferred in guided tubes to the respective injection locations. Pellet speed variation with pressure at different pellet formation temperatures has been observed. Pellet intactness tests through these guide tubes show a variation in the intact speed limit over a range of pellet formation temperatures from 6.5 to 9.8 K. Pellet speed reduction of less than 6% has been observed after the pellet moves through the curved guide tubes.

Disentangling the dynamical origin of P11 nucleon resonances

We show that two almost degenerate poles near the piDelta threshold and the next higher mass pole in the P11 partial wave of piN scattering evolve from a single bare state through its coupling with piN, etaN, and pipiN reaction channels. This finding provides new information on understanding the dynamical origins of the Roper N{*}(1440) and N{*}(1710) resonances listed by Particle Data Group. Our results for the resonance poles in other piN partial waves are also presented.

Relationships between leaching of methylmercury from the soil and the basic characteristics of alkali soil polluted by mercury in Guizhou China

To determine the relationship between soluble methylmercury and soil characteristics which was contaminated by mercury, several experiments were conducted. As a result, a good correlation was founding between the leached methylmercury level from soil and the EC (electronic conductivity) level of soil. Moreover, to grasp the relationship between soluble methylmercury and soluble anions from soil, several anions (Cl(-), NO(3-), SO(4) (2-)) were measured using the ion chromatography method. Although the correlation coefficient was small (r = 0.40), only a correlation between the level of SO(4) (2-) and leached methylmercury was recognized.

Improved ECG signal analysis using wavelet and feature extraction

OBJECTIVES

Automatic detection of arrhythmias is important for diagnosis of heart problems. However, in ECG signals, there is significant variation of waveforms in both normal and abnormal beats. It is this phenomenon, which makes it difficult to analyse ECG signals. The aim of developing methodology is to distinguish between normal beats and abnormal beats in an ECG signal.

METHODS

ECG signals were first decomposed using wavelet transform. The feature vectors were then extracted from these decomposed signals as normalised energy and entropy. To improve the classification of the feature vectors of normal and abnormal beats, the normal beats which occur before and after the abnormal beats were eliminated from the group of normal beats.

RESULTS

With our proposed methods, the normal beats and abnormal beats formed different clusters of vector points. By eliminating normal beats which occur before and after the abnormal beats, the clusters of different types of beats showed more apparent separation.

CONCLUSIONS

The combination of wavelet decomposition and the classification using feature vectors of the beats in ECG signals separate abnormal beats from normal beats. The elimination of the normal beats which occur before and after the abnormal beats succeeded in minimising the size of normal beats cluster.

The genome-wide screening of yeast deletion mutants to identify the genes required for tolerance to ethanol and other alcohols

A set of homozygous diploid deletion mutants of the yeast Saccharomyces cerevisiae was screened for the genes required for tolerance to aliphatic alcohols. The screen identified 137, 122 and 48 deletion mutants sensitive to ethanol, 1-propanol and 1-pentanol, respectively. A number of the genes required for ethanol tolerance were those also required for tolerance to other alcohols. Numerous mutants with defective genes encoding for vacuolar H+ -ATPase (V-ATPase) were cosensitive to these alcohols. A global screening approach of yeast deletion library mutants was useful in elucidating the mechanisms of alcohol tolerance based on different lipophilicities.

Cytogenetic analysis of myxoid liposarcoma and myxofibrosarcoma by array-based comparative genomic hybridisation

AIM

To investigate overall chromosomal alterations using array-based comparative genomic hybridisation (CGH) of myxoid liposarcomas (MLSs) and myxofibrosarcomas (MFSs).

MATERIALS AND METHODS

Genomic DNA extracted from fresh-frozen tumour tissues was labelled with fluorochromes and then hybridised on to an array consisting of 1440 bacterial artificial chromosome clones representing regions throughout the entire human genome important in cytogenetics and oncology.

RESULTS

DNA copy number aberrations (CNAs) were found in all the 8 MFSs, but no alterations were found in 7 (70%) of 10 MLSs. In MFSs, the most frequent CNAs were gains at 7p21.1-p22.1 and 12q15-q21.1 and a loss at 13q14.3-q34. The second most frequent CNAs were gains at 7q33-q35, 9q22.31-q22.33, 12p13.32-pter, 17q22-q23, Xp11.2 and Xq12 and losses at 10p13-p14, 10q25, 11p11-p14, 11q23.3-q25, 20p11-p12 and 21q22.13-q22.2, which were detected in 38% of the MFSs examined. In MLSs, only a few CNAs were found in two sarcomas with gains at 8p21.2-p23.3, 8q11.22-q12.2 and 8q23.1-q24.3, and in one with gains at 5p13.2-p14.3 and 5q11.2-5q35.2 and a loss at 21q22.2-qter.

CONCLUSIONS

MFS has more frequent and diverse CNAs than MLS, which reinforces the hypothesis that MFS is genetically different from MLS. Out-array CGH analysis may also provide several entry points for the identification of candidate genes associated with oncogenesis and progression in MFS.

The application of wavelet and feature vectors to ECG signals

The Electrocardiogram (ECG) is one of the most commonly known biological signals. Traditionally ECG recordings are analysed in the time-domain by skilled physicians. However, pathological conditions may not always be obvious in the original time-domain signal. Fourier analysis provides frequency information but has the disadvantage that time characteristics will be lost. Wavelet analysis, which provides both time and frequency information, can overcome this limitation. Here a new method, the combination of wavelet analysis and feature vectors, is applied with the intent to investigate its suitability as a diagnostic tool. ECG signals with normal and abnormal beats were examined. There were two stages in analysing ECG signals: feature extraction and feature classification. To extract features from ECG signals, wavelet decomposition was first applied and feature vectors of normalised energy and entropy were constructed. These feature vectors were used to classify signals. The results showed that normal beats and abnormal beats composed different clusters in most cases. In conclusion, the combination of wavelet transform and feature vectors has shown potential in detecting abnormalities in an ECG recording. It was also found that normalised energy and entropy are features, which are suitable for classification of ECG signals.

Plasma ghrelin levels in healthy elderly volunteers: the levels of acylated ghrelin in elderly females correlate positively with serum IGF-I levels and bowel movement frequency and negatively with systolic blood pressure

Aging is associated with a decrease in growth hormone (GH) secretion, appetite and energy intake. As ghrelin stimulates both GH secretion and appetite, reductions in ghrelin levels may be involved in the reductions in GH secretion and appetite observed in the elderly. However, only preliminary studies have been performed on the role of ghrelin in elderly subjects. In this study, we sought to clarify the physiologic implications of the age-related alterations in ghrelin secretion by determining plasma ghrelin levels and other clinical parameters in healthy elderly subjects. Subjects were > or = 65 years old, corresponding to the SENIEUR protocol, had not had a resection of the upper gastrointestinal tract and had not been treated with hormones. One hundred and five volunteers (49 men and 56 women) were admitted to this study (73.4 +/- 6.3 years old). Plasma levels of acylated ghrelin in elderly female subjects positively correlated with serum IGF-I levels and bowel movement frequency and negatively with systolic blood pressure. In elderly men, desacyl ghrelin levels correlated only weakly with bowel movement frequency. These findings suggest that the plasma levels of the acylated form of ghrelin may influence the age-related alterations in GH/IGF-I regulation, blood pressure and bowel motility. These observational associations warrant further experimental studies to clarify the physiologic significance of these effects.

A novel NADH-dependent carbonyl reductase from Kluyveromyces aestuarii and comparison of NADH-regeneration system for the synthesis of ethyl (S)-4-chloro-3-hydroxybutanoate

To compare NADH-regeneration systems for the synthesis of (S)-4-chloro-3-hydroxybutanoate (ECHB), a novel NADH-dependent carbonyl reductase (KaCR1), which reduced ethyl 4-chloroacetoacetate (ECAA) to form (S)-ECHB, was screened and purified from Kluyveromyces aestuarii and a gene encoding KaCR1 was cloned. Glucose dehydrogenase (GDH) and formate dehydrogenase (FDH) were compared as enzymes for NADH regeneration using Escherichia coli cells coexpressing each enzyme with KaCR1. E. coli cells coexpressing GDH produced 45.6 g/l of (S)-ECHB from 50 g/l of ECAA and E. coli cells coexpressing FDH, alternatively, produced only 19.0 g/l. The low productivity in the case of FDH was suggested to result from the low activity and instability of FDH.

Comprehensive gene expression analysis of the response to straight-chain alcohols in Saccharomyces cerevisiae using cDNA microarray

AIMS

The purpose of this study was to examine the gene expression profiles of yeast Saccharomyces cerevisiae subjected to straight-chain alcohols.

METHODS AND RESULTS

Lipophilic alcohols with high log Pow values were more toxic to yeast than those with low log Pow values. Morphological changes after exposure to ethanol, 1-pentanol, 1-octanol were observed, whereas n-pentane as a model hydrocarbon affected the surface of the outer membrane, with little change in organelles. Using cDNA microarrays, quite a few up-regulated gene categories were classified into the category 'cell rescue, defence and virulence' by ethanol, and the category 'energy' and 'metabolism' by 1-pentanol. Meanwhile, the characteristic genes up-regulated by n-pentane were not observed, and the expression profile was distantly related to ethanol, 1-pentanol and 1-octanol.

CONCLUSIONS

This study suggests that gene expression profiles at the whole genome level were intimately associated with the cell growth inhibition and morphological changes by straight-chain alcohols with differing log Pow values.

SIGNIFICANCE AND IMPACT OF THE STUDY

The study of comprehensive gene expression profiles by cDNA microarrays elucidates the straight-chain alcohol adaptation mechanisms.

Common fragile genes

Common chromosome fragile sites show susceptibility to DNA damage, leading to alterations that contribute to cancer development. The cloning and characterization of fragile sites have demonstrated that fragile sites are associated with genes that relate to tumorigenesis. Identification of the basis of instability at fragile sites and the related genes provides an entree to understanding of important aspects of chromosomal instability, a prominent feature of neoplastic genomes. FHIT/FRA3B and WWOX/FRA16D, the most sensitive common fragile genes in the human genome, function as tumor suppressor genes. The common features of these two common fragile genes are summarized, and suggest clues to understanding the relation between genomic instability and tumor biology.

Synthesis of ethyl ( S)-4-chloro-3-hydroxybutanoate using fabG-homologues

This paper is a report on the successful application of bioinformatics to enzyme screening. The synthesis of ethyl ( S)-4-chloro-3-hydroxybutanoate (ECHB) by asymmetric reduction of ethyl 4-chloroacetoacetate (ECAA) using fabG-homologues was studied. beta-Ketoacyl-acyl carrier protein reductases from both Escherichia coli and Bacillus subtilis, which are components of type II fatty acid synthase, could reduce ECAA to ( S)-ECHB with 94-98% ee. Furthermore, acetoacetyl-CoA reductases (ARs) from both Ralstonia eutropha and Zoogloea ramigera, whose genes are significantly similar to fabG genes and play a physiological role in the biosynthesis of poly-beta-3-hydroxybutyrate, could also catalyze the asymmetric reduction of ECAA to ( S)-ECHB with >99% ee. ( S)-ECHB was synthesized to 48.7 g/l with an optical purity of 99.8% ee, using recombinant E. coli cells coexpressing AR from R. eutropha and glucose dehydrogenase from B. subtilis for the regeneration of NADPH.

Non-uniformities in polymer/liquid crystal mixtures I. Interfacial tension

We theoretically study interfacial properties between two coexisting phases in mixtures of a flexible polymer and a low-molecular-weight liquid crystal. By numerically solving Euler equations for compositional and orientational order parameter fields, we calculate the order parameter profiles and interfacial tensions for nematic-isotropic and isotropic-isotropic phase equilibria. We find that the order parameter profiles are non-monotonic at some temperatures. The nematic-isotropic interfacial tension increases with decreasing temperature and is approximately proportional to (T - T(NI))(n) at temperatures below the nematic-isotropic transition temperature (T(NI)) of the pure nematogen. The value of the exponent n is strongly affected by the existence of a triple point.

Non-uniformities in polymer/liquid crystal mixtures II. Nematic nucleation

We theoretically model the nucleation of nematic droplets during phase ordering in mixtures of a flexible polymer and a low-molecular-weight liquid crystal. By appealing to classical nucleation theory (CNT), we calculate the energy barrier to nucleation and the size of a critical nucleus. We study the influence of a metastable intermediate phase on the nucleation of the nematic. Below a triple point in the phase diagram, there are two distinct mechanisms for the formation of a nematic nucleus: 1) direct nucleation from the isotropic phase and 2) nucleation via a precursor metastable isotropic phase. We calculate the crossover concentration as a function of temperature, delineating the regions of the phase diagram in which each mechanism prevails. In the latter case, the presence of a hidden metastable isotropic-isotropic binodal may either promote or delay the nucleation of a nematic phase.

Purification and properties of a carbonyl reductase useful for production of ethyl (S)-4-chloro-3-hydroxybutanoate from Kluyveromyces lactis

A novel carbonyl reductase (KLCR1) that reduced ethyl 4-chloroacetoacetate (ECAA) to synthesize ethyl (S)-4-chloro-3-hydroxybutanoate ((S)-ECHB) was purified from Kluyveromyces lactis. KLCR1 catalyzed the NADPH-dependent reduction of ECAA enantioselectively but not the oxidation of (S)-ECHB. From partial amino acid sequences, KLCR1 was suggested to be an alpha subunit of fatty acid synthase (FAS) but did not have FAS activity.

Synthesis of (R)-1,3-butanediol by enantioselective oxidation using whole recombinant Escherichia coli cells expressing (S)-specific secondary alcohol dehydrogenase

The synthesis of (R)-1,3-butanediol (BDO) from its racemate was studied using whole cells of recombinant Escherichia coli expressing an (S)-specific secondary alcohol dehydrogenase (CpSADH) from Candida parapsilosis by enantioselective oxidation. Under the optimized conditions, the yield of (R)-1,3-BDO reached 72.6 g/l, with a molar recovery yield of 48.4% from a racemate of 15% and an optical purity of 95% ee.