Laccase initiated oxidative domino reactions for the efficient synthesis of 3,4-dihydro-7,8-dihydroxy-2H-dibenzofuran-1-ones

Laccase initiated domino reactions of cyclohexane-1,3-diones with catechols using air as an oxidant afford 3,4-dihydro-7,8-dihydroxy-2H-dibenzofuran-1-ones with yields ranging from 70% to 97%.     

Solar-microclimate study in urban areas

Summary A study on solar microclimates in eight medium and large European cities, supported by EEC from 1986 to 1988, could allow to mark the main resemblances and anomalies in the solar-radiation features in different geographical and climatic regions in Northern, Central and Southern Europe and also to achieve reliable estimates of available energy in thermal-conversion processes of solar radiation. This paper presents the results of an analysis of solar-radiation observations taken during the EEC study and discusses the main solar climatic peculiarities of the urban area of Turin (one of the eight cities involved in this project), comparing them to other European regions (south and north of Turin).     

Conditioning convex and nonconvex problems

Two ways of defining a well-conditioned minimization problem are introduced and related, with emphasis on the quantitative aspects. These concepts are used to study the behavior of the solution sets of minimization problems for functions with connected sublevel sets, generalizing results of Attouch-Wets in the convex case. Applications to continuity properties of subdifferentials and to projection mappings are pointed out.We are grateful to M. Valadier for pointing out, during a lecture by the author in Montpellier in October 1990 presenting the main results of the present paper, that existence results in Section 2 of the present paper can be dissociated from estimates.     

气垫船稳态船波势及波阻的边界元法

本文给出了气垫船在静水中航行时稳态船波势问题的边界元数值分析方法，根据本文的数值计算方法，可以得到气垫船行时所兴起的波浪形状以及气垫附近流场情况，由此可计算气垫所受到的兴波阻力，本文的方法适用于任意已知气压分布情况。     

Direct and rapid analysis of ambient air and exhaled air via electrostatic precipitation of aerosols in an atomizer furnace and Zeeman spectrometry

Techniques that allow the elements present in the air to be determined in a simple and rapid manner are very attractive. Direct aerosol sampling techniques avoid the need to pretreat the filter via wet digestion in order to remove any sources of contamination, and they decrease the precipitation time significantly. Analyzers based on this technique can also determine the concentrations of elements in the air automatically in situ. This paper is concerned with the development of a novel analytical system that is based on electrostatically precipitating aerosols from the air into a graphite furnace. The equipment includes a Zeeman spectrometer with high frequency modulation polarization (MGA-915), and an electrostatic precipitation system incorporated into the analyzer. The high sensitivity of the system developed here means that it can be used to determine element concentrations in the air exhaled by humans, as well as those in ambient air.     

非定常空气流场中污染气体的对流与粘性扩散

基于离散涡方法求得的非定常、不稳定空气流场，数值求解了污染气体在空气中的对流湍流扩散方程．两者在每一个时间步耦合，以求非定常对流项．考虑速度脉动，改进了扩散模式．用SF6作为示踪气体，进行了现场测量实验．测得了各测点的SF6浓度随时间的变化．实验结果与数值仿真进行了对比，两者吻合．     

Simultaneous derivatization/preconcentration of volatile aldehydes with a miniaturized fiber-packed sample preparation device designed for gas chromatographic analysis

A novel in-needle sample preparation device has been developed for the determination of volatile aldehydes in gaseous samples. The needle device is designed for the gas chromatographic (GC) analysis of aldehydes and ketones commonly found in typical in-house environments. In order to prepare the extraction device, a bundle of polymer-coated filaments was longitudinally packed into a specially designed needle. Derivatization reactions were prompted by 2,4-dinitrophenylhydrazine (NDPH) included in the needle, and so the aldehydes and ketones were derivatized to the corresponding hydrazones and extracted with the extraction needle. A reproducible extraction needle preparation process was established, along with a repeatable derivatization/extraction process that ensures the successful determination of aldehydes. The storage performance of the extraction needle was also evaluated at room temperature for three days. The results demonstrate the successful application of the fiber-packed extraction device to the preparation of a gaseous sample of aldehydes, and the future possibility of applying the extraction device to the analysis of in-house environments.     

Circumventing air bubbles in microfluidic systems and quantitative continuous-flow PCR applications

Polymerase chain reaction (PCR) is an essential part of research based on genomics or cell analysis. The development of a microfluidic device that would be suitable for high-temperature-based reactions therefore becomes an important contribution towards the integration of micro-total analysis systems (μTAS). However, problems associated with the generation of air bubbles in the microchannels before the introduction of the assay liquid, which we call the “initial start-up” in this study, made the flow irregular and unstable. In this report, we have tried to address these problems by adapting a novel liquid-flow method for high-temperature-based reactions. A PDMS-based microfluidic device was fabricated by soft-lithography techniques and placed on a cartridge heater. The generation of the air bubbles was prevented by introducing the fluorinated oil, an inert and highly viscous liquid, as the cap just before the introduction of the sample solutions into the microchannels. The technique was applied for continuous-flow PCR, which could perform PCR on-chip in a microfluidic system. For the evaluation of practical accuracy, plasmid DNA that serves as a reference molecule for the quantification of genetically modified (GM) maize was used as the template DNA for continuous-flow PCR. After PCR, the products were collected in a vial and analyzed by gel electrophoresis to confirm the accuracy of the results. Additionally, quantitative continuous-flow PCR was performed using TaqMan technology on our PCR device. A laser detection system was also used for the quantitative PCR method. We observed a linear relationship between the threshold cycle (Ct) and the initial DNA concentration. These results showed that it would be possible to quantify the initial copies of the template DNA on our microfluidic device. Accurate quantitative DNA analysis in microfluidic systems is required for the integration of PCR with μTAS, thus we anticipate that our device would have promising potential for applications in a wide range of research.     

水中气泡光散射动态特征及其与水粒光散射特征的对比研究

基于VirtualLab虚拟仿真软件建立了粒径在几十到几百微米内不同大小和形状的气泡模型。对其在平面光照射下的散射进行了仿真模拟,得到了气泡的前向、后向光散射特征分布,将结果与水粒的光散射特征进行比较分析,发现:同一气泡前向散射远大于后向散射,但两者拥有十分相近的变化趋势。光源和气泡大小影响气泡远场散射幅值的大小、振荡频率、角宽度及次极大与主极大的比值。气泡结构的对称性影响着气泡远场散射的对称性。气泡与水粒的远场散射特性既联系又区别。该研究的结果可以为气泡的分析检测提供了一定的理论依据。     

Variations of Lead Isotopes and Airborne Particulate Concentrations From the Kozani Basin,West Macedonia,Greece

Abstract

The spread and variation in ²⁰⁶Pb/²⁰⁷Pb ratios make Pb isotopes a powerful tool when it comes to detecting trends in airborne particulates originating mainly from power plants. This study was conducted to determine the source of pollution in Kozani area, an affected industrial area. Lead isotopic ratios of air filters under certain meteorological conditions were compared to Pb isotope analyses sampled from lignite mines, but also to Pb isotope analyses of cultivations in soil originating from the reclamation of old abandoned lignite-mines. The particles taken into consideration have an aerodynamic diameter less than 10 μm (PM10). The measurements were carried out in a central part of the town of Kozani, West Macedonia, for one year observation period. The lead isotope values of air filters and of wheat in the Kozani area are between the values of lignite Pb and of Greek gasoline.