Enzymatic preparation of arbutin derivatives: Lipase-catalyzed direct acylation without the need of vinyl ester as an acyl donor

Direct and regioselective acylation of arbutin with aromatic or aliphatic acid using a lipase obtained from Candida antarctica in an organic solvent was investigated. We achieved the enzymatic synthesis of feruloyl arbutin and lipoyl arbutin without the need of vinyl ferulate and vinyl lipoate as acyl donors, respectively.     

脱排一体式钢塔设置TMD对减轻风致振动的 控制研究

为了减轻脱排一体式钢塔的风致振动,采用调谐质量阻尼器(TMD)控制装置,对其进行风振控制研究。利用ADINA有限元软件,进行脱排一体式钢塔的风洞数值模拟与时程分析,并对脱排一体式钢塔结构进行现场实测,现场实测结果与数值模拟结果误差在15%之内,验证了数值模拟方法的准确性。根据脱排一体式钢塔的结构特性,合理设计了TMD控制装置。进行风荷载作用下设置TMD的脱排一体式钢塔时程分析,结果表明,TMD控制装置可以增加脱排一体式钢塔的等效阻尼比,有效降低脱排一体式钢塔的整体位移、加速度响应与结构底部应力响应,但会增大结构上部与中部的应力响应。TMD与主体结构相对位移较小,可对TMD控制装置进行优化设计。     

Optical Properties of Au-Pt and Au-Pt-In Alloys

The effects of platinum addition to gold and indium addition to a gold-platinum alloy on their optical properties were investigated using a computer-controlled spectrophotometer. Spectral reflectance data from a polished sample for the incident CIE standard illuminant D65 was collected as a function of the wavelength at 10 nm intervals from 360 to 740 nm. Three coordinates,L* (lightness),a* (red-green),b* (yellow-blue), in the CIE 1976L*a*b* colour space, were determined to quantify the colour of experimental binary Au-Pt and ternary Au-Pt-In alloys. p ]The pronounced step near 520 nm (approximately 2.4 eV) in the spectral reflectance-wavelength curve for pure gold, which is responsible for the rich yellow colour of gold, became less pronounced with the addition of platinum. The decoloring effect of platinum was found to be due to this phenomenon. The addition of indium of up to ca 4 at% to a Au-10 at% Pt alloy increased both chromaticity indices, ie,a* andb* values, giving a gold tinge to the alloy: this effect was brought about by both the slight increase in reflectance in the long-wavelength range and the slight decrease in reflectance in the short-wavelength range of the visible spectrum.     

SERS microscopic imaging as novel tool for assessing viability and enumerating yeast cells at various stages of cell cycle in lag,log, exponential and stationary phases of growth in culture

Surface enhanced Raman scattering (SERS) microscopic imaging was employed to enumerate the yeast cells in culture. We found this imaging method as an efficient tool for easily differentiating and quantitatively enumerating yeast cell at different stages of cell-division cycle (G1, S, G2 and M phase) at various stages of growth phases namely lag, log, exponential and stationary phases in culture. Apart from enumerating the cells at different stages of cell cycle under lag, log, exponential and stationary phases, it was possible using SERS microscopy to differentiate the live cells from dead ones. The dead cells were SERS inactive and gave enhanced autofluorescence compared with the live cells, which were SERS active. The results from the present investigation suggest that SERS microscopic imaging, using silver nanoparticles (AgNPs) as a sensitive tool to enumerate the yeast cells in culture.     

New approaches to fabrication of multilayer Fresnel zone plate for high-energy synchrotron radiation X-rays

A multilayer (sputtered-sliced) Fresnel zone plate (FZP) is one of the promising focusing optics with high spatial resolution for the high-energy X-ray region. This is because a large “aspect ratio” can be realized easily. In addition, it is important that the kinoform FZP (theoretical diffraction efficiency=100%) can be fabricated by the sputtered-sliced method. This paper presents the experimental results of two new approaches for fabrication of a multilayer FZP for X-rays. (1) To achieve higher diffraction efficiency, a multilevel-type (4-step: quasi-kinoform type) FZP was fabricated. This FZP was composed of concentric multilayers of alternating high-Z, low-Z, and composite materials. The composite material layer was deposited by co-sputtering of high-Z and low-Z materials. (2) To achieve smoother zones (multilayer interfaces) at the conventional-type FZP, each target of a sputtering apparatus with two DC-sputtering guns was surrounded by a cover with an aperture, and Ar gas was supplied inside the cover, which led to the deposition at lower Ar gas pressure. As a result, for the former, the efficiency was improved markedly as compared with conventional FZP, and for the latter, the zone roughness was reduced, which has resulted in the improvement of the spatial resolution of the FZP.     

Characterization of vps33+, a gene required for vacuolar biogenesis and protein sorting in Schizosaccharomyces pombe

From the fission yeast Schizosaccharomyces pombe we have identified and deleted vps33, a gene encoding a homologue of VPS33, which is required for vacuolar biogenesis in S. cerevisiae cells. When the vps33(+) gene is disrupted, Sz. pombe strains are temperature-sensitive for growth and contain numerous small vesicular structures stained with FM4-64 in the cells. Deletion of the Sz. pombe vps33(+) gene results in pleiotropic phenotypes consistent with the absence of normal vacuoles, including missorting of vacuolar carboxypeptidase Y, various ion- and drug-sensitivities, and sporulation defects. These results are consistent with Vps33p being necessary for the morphogenesis of vacuoles and subsequent expression of vacuolar functions in Sz. pombe cells.     

The thermal mechanism of warm in winter and cool in summer in China traditional vernacular dwellings

Yaodong is one representative of western China vernacular dwellings. Its indoor thermal environment is cool in summer and warm in winter. This study interprets the characteristic of warm in winter and cool in summer in such a dwelling by measuring the indoor, outdoor and wall’s temperatures in winter and summer. The human thermal comfort theory is used to evaluate thermal environment, and the periodic heat transfer mechanism is used to analyze the thermal transfer through the wall. The results show that the Yaodong thick wall effectively damping external temperature wave and keeping steady inner surface temperature are the chief causes of warm in winter and cool in summer in Yaodong, which lays a scientific basis for low energy building design.     

Solidification of Sn-0.7Cu-0.15Zn Solder: In Situ Observation

High resolution time-resolved X-ray imaging with synchrotron radiation was used for in situ observation of four distinct events during solidification of a Sn-0.7Cu-0.15Zn solder despite small composition and density differences. These included βSn dendrite growth, Sn-Cu₆Sn₅ univariant eutectic growth, microporosity formation, and a polyphase reaction in the last stages of freezing. The development of microstructure was described quantitatively by tracking the loci of dendrite tips during grain growth. The results have implications for microstructure control and the understanding of structure–property relationships in Sn-Cu-Zn lead-free solders.     

Comparison of two possible routes of pathogen contamination of spinach leaves in a hydroponic cultivation system

The route of pathogen contamination (from roots versus from leaves) of spinach leaves was investigated with a hydroponic cultivation system. Three major bacterial pathogens, Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes, were inoculated into the hydroponic solution, in which the spinach was grown to give concentrations of 10? and 103 CFU/ml. In parallel, the pathogens were inoculated onto the growing leaf surface by pipetting, to give concentrations of 10? and 103 CFU per leaf. Although contamination was observed at a high rate through the root system by the higher inoculum (10? CFU) for all the pathogens tested, the contamination was rare when the lower inoculum (103 CFU) was applied. In contrast, contamination through the leaf occurred at a very low rate, even when the inoculum level was high. For all the pathogens tested in the present study, the probability of contamination was promoted through the roots and with higher inoculum levels. The probability of contamination was analyzed with logistic regression. The logistic regression model showed that the odds ratio of contamination from the roots versus from the leaves was 6.93, which suggested that the risk of contamination from the roots was 6.93 times higher than the risk of contamination from the leaves. In addition, the risk of contamination by L. monocytogenes was about 0.3 times that of Salmonella enterica subsp. enterica serovars Typhimurium and Enteritidis and E. coli O157:H7. The results of the present study indicate that the principal route of pathogen contamination of growing spinach leaves in a hydroponic system is from the plant's roots, rather than from leaf contamination itself.