黏性不可压流体的自适应网格技术和基本特性方程分离算法的联合分析

组合基本特性方程分离算法和自适应网格技术,分析二维黏性不可压流体.该方法使用3节点三角单元,对速度分量和压力等变量分析,使用等阶次的插值函数.组合解法的主要优点在于,在自适应网格技术中,对解梯度变化大的区域,通过耦合误差估计生成小的单元,利于提高解的精度,在其它区域生成大单元,可以节省时间.最后,通过对一个黏性流体圆柱体绕流问题的瞬态和稳态特性分析,给出了组合解法性能的评价.     

Highly volatile constituents of Vetiveria zizanioides roots grown under different cultivation conditions

Roots of Vetiveria zizanioides Nash (Mae Hae; Thai ecotype) planted in three different cultivation systems (normal soil, normal soil with added microbes and semi- hydroponically) were extracted using a simultaneous steam distillation and solvent extraction (SDE) apparatus. Yields of the essential oils obtained were 0.27, 0.18 and 0.06%, respectively. The separation profiles obtained by comprehensive two-dimensional gas chromatography (GCxGC) and solid phase microextraction (SPME)-GCxGC analyses of the crude essential oils showed a total of 156 and 48 well-resolved components, respectively. The highly volatile fractions isolated from the three essential oils by SPME were subjected to analysis by GC-MS and 42 compounds were identified in total. Volatile component profiles of the oils obtained by normal soil and semi-hydroponic cultivation were similar, whereas a quantitative difference was noted in some major volatiles when the cultivation system containing microbes was utilized.     

Synthesis and Characterization of Amino Acid Modified Chitooligosaccharides

Amino acid modified chitooligosaccharides were synthesized by the new synthetic route. The chloroacetyl-chitooliogosaccharide intermediates were prepared under a mild condition via a reaction between chitooligosaccharide (COS) and chloroacetic anhydride. The intermediates were subsequently reacted with a variety of amino acids, e.g., glycine, aspartic acid, alanine, arginine, and serine, under a basic condition, yielding amino acid modified COS products. The degree of chloroacetylation was calculated based on new ¹H NMR absorption peaks at 3.80 and 3.94 ppm, corresponding to  NH CO CH₂ Cl and  O CO CH₂ Cl, respectively. The degrees of chloroacetylation determined were 0.40, 0.44, 0.62, and 0.93 when the mole ratios of chloroacetic anhydride to COS were 0.5, 1, 2, and 4, respectively. The chemical structures of the COS derivatives were also determined using ¹H NMR spectroscopy. The biological properties of the derivatives were evaluated. Cytotoxicity of the derivatives was assessed by a direct contact, using L929 cells. An MTT assay was a method of choice to evaluate the efficacy of the derivatives to enhance the proliferation of L929 cells.     

A Novel Serum Glycobiomarker for Diagnosis and Prognosis of Cholangiocarcinoma Detected by Butea monosperma Agglutinin

Plant lectins are widely used in medical glycosciences and glycotechnology. Many lectin-based techniques have been applied for the detection of disease-associated glycans and glycoconjugates. In this study, Butea monosperma agglutinin (BMA), a lectin purified from seeds of the medicinal plant Butea monosperma, was used for the detection of cholangiocarcinoma (CCA)-associated glycans. Expression of BMA-binding N-acetyl galactosamine/galactose (GalNAc/Gal)-associated glycan (BMAG) in CCA tissues was determined using BMA lectin histochemistry; the results showed that BMAG was undetectable in normal bile ducts and drastically increased in preneoplastic bile ducts and CCA. The study in hamsters showed that an increase of BMAG was associated with carcinogenesis of CCA. Using an in-house double BMA sandwich enzyme-linked lectin assay, BMAG was highly detected in the sera of CCA patients. The level of serum BMAG in CCA patients (N = 83) was significantly higher than non-CCA controls (N = 287) and it was applicable for diagnosis of CCA with 55.4% sensitivity, 81.9% specificity, and 76.0% accuracy. A high level of serum BMAG (≥82.5 AU/mL) was associated with unfavorable survival of CCA patients; this information suggested the potential of serum BMAG as a poor prognostic indicator of CCA. In summary, BMAG was aberrantly expressed in preneoplastic bile ducts and CCA, it was also highly detected in patient serum which potentially used as a marker for diagnosis and prognostic prediction of CCA.     

A novel one-pot synthesis of derivatives of aryldioxins and aryldithiins

One-pot reactions between ortho-dihydroxyarenes with 1,2-diols or dithiols in the presence of p-toluenesulfonic acid yielded the corresponding dioxins or dithiins in good to excellent yields.     

Model compound studies

The influence of other hemicellulosic sugars (arabinose, galactose, mannose, and glucose), oxygen limitation, and initial xylose concentration on the fermentation of xylose to xylitol was in vestigated using experimental design methodology. Oxygen limitation and initial xylose concentration had strong influences on xylitol production by Candida tropicalis ATCC 96745. Under semiaerobic conditions, xylitol yield was highest (0.62 g/g), whereas under aerobic conditions volumetric productivity was highest (0.90g/[L·h]). In the presence of glucose, xylose utilization was strongly repressed and sequential sugar utilization was observed. Ethanol produced from the glucose caused a 50% reduction in xylitol yield when the ethanol con centration exceeded 30 g/L. When complex synthetic hemicellulosic sugars were fermented, glucose was initially consumed followed by a simultaneous uptake of the other sugars. The highest xylitol yield (0.84 g/g) and volumetric productivity (0.49 g/[L·h]) were obtained for substrates containing high arabinose and low glucose and mannose contents.     

Identification of Newly Zeaxanthin-Producing Bacteria Isolated from Sponges in the Gulf of Thailand and their Zeaxanthin Production

Sponge-associated bacteria have been found to produce a variety of bioactive compounds including natural pigments. Here, we report the molecular identification of zeaxanthin-producing sponge-associated bacteria isolated from sponges in the Gulf of Thailand and the effect of environmental factors on zeaxanthin production from a bacterium. Three colorful sponge-associated bacteria (CHOB06-6, KODA19-6, and MAKB08-4) were identified based on the 16S rDNA profile. The 16S rDNA sequence-based analyses revealed that CHOB 06-6 and MAKB 08-4 were the closest relatives to Sphingomonas phyllosphaerae FA2^T, and KODA19-6 was a relative of Shingomonas (Blastomonas) natatoria DSM 3183^T. After all bacteria were cultivated in a modified Zobell medium, S. natatoria KODA19-6 was found to produce the highest zeaxanthin at 0.62?mg/l. pH and temperature considerably affected its zeaxanthin production. Its optimal condition for zeaxanthin production was found at a pH of 7 and 30?°C. The bacterium had a maximum specific growth rate (?? _max) of 0.06?1/h with zeaxanthin productivity (Q _p) of 6.27???g/l·h. Therefore, this newly zeaxanthin-producing bacterium has a potential to produce natural zeaxanthin for the food, feed, pharmaceutical, and cosmetic industries.