Enantioseparation of catechin and epicatechin in plant food by chiral capillary electrophoresis

The enantiomers of catechin and epicatechin were separated by chiral capillary electrophoresis using modified cyclodextrins as chiral selectors. Various conditions for the separation system were optimized, including the pH value and the concentration of the running buffer. A baseline separation of the catechin and epicatechin enantiomers could be achieved by using 0.1 mol l⁻¹ borate buffer (pH 8.5) with 12 mmol l⁻¹ (2-hydroxypropyl)-γ-cyclodextrin as chiral selector, a fused-silica capillary with 40 cm effective length (75 μm I.D.), +18 kV applied voltage, a temperature of 20 °C and direct UV detection at 280 nm. The method was applied to different plant food samples. (+)-Catechin and (−)-epicatechin could be verified as the most common flavan-3-ols. In the case of guaraná, however, we were able to identify all four enantiomers, both (+)- and (−)-catechin and (+)- and (−)-epicatechin, as naturally occurring compounds. This finding was verified by further isolation and purification of the flavan-3-ols and subsequent LC–MS analysis. This method allows for the identification of the authenticity of guaraná through the analysis of the catechin and epicatechin enantiomers, additionally to the conventional methods like HPLC.     

Performance Characteristics of a Drying Heat Pump Using Superheated Steam

A complete mathematicalhumerical model is proposed, in order to simulate the performance characteristics of a novel concept of a drying heat pump based on the theory of minimum energy cyclcs. The drying heat pump involvcs vapour condensation in a Lava1 nozzle. removal of the liquid phase in a supersonic separator as well as compression of the working medium. which is superheared vapour.     

Study on phase behavior–impact strength relationship of unsaturated polyester/polyurethane hybrid polymer network

The phase behavior of a hybrid polymer network (HPN) composed of poly[(propylene glycol maleate)-co-(propylene glycol phthalate)] crosslinked with styrene and polyester–urethane crosslinked with methylene-bis-ortho-chloroaniline was examined. The correlation between phase separation and impact strength of the HPNs is discussed. The composition of HPNs has an effect on their properties.     

K_2O－B_2O_3－SiO_2玻璃成分对析晶性能的影响

本文利用ＤＴＡ、ＸＲＤ、ＴＥＭ、ＳＥＭ等技术研究了三种Ｋ２Ｏ－Ｂ２Ｏ３－ＳｉＯ２玻璃的析晶性能。结果表明，Ｋ２Ｏ－Ｂ２Ｏ３－ＳｉＯ２玻璃的析晶由分相引起，分相和析晶能力受成分影响较大。随Ｂ２Ｏ３和Ｋ２Ｏ含量增多及Ｋ２Ｏ／Ｂ２Ｏ３比值的降低，析晶加强。析晶中主晶相类别尚未查清，次晶相确定为α－方石英。     

NUMERICAL SIMULATION OF PARTICLE SEPARATION IN AN OIL-SAND SEPARATOR

ＮＯＴＡＴＩＯＮＳＡ　Ａｒｅａｏｆｉｎｌｅｔ ,ｍ2ａ　Ｃｅｎｔｒｉｆｕｇａｌａｃｃｅｌｅｒａｔｉｏｎ ,ｍ2 /ｓｉ　Ｇｒｉｄｏｆａｘｉａｌｄｉｒｅｃｔｉｏｎｍｌ 　ＭａｘｉｍｕｍｇｒｉｄｎｕｍｂｅｒｏｆｒａｄｉａｌｄｉｒｅｃｔｉｏｎＱ　Ｆｌｕｉｄｍａｓｓｒａｔｅ ,ｍ3/ｓＲｃ 　Ｍａｘｉｍｕｍｒａｄｉｕｓｏｆｃｙｃｌｏｎｅ ,ｍＲｅ　Ｒｅｙｎｏｌｄｓｎｕｍｂｅｒｒ　Ｄｉｍｅｎｓｉｏｎｌｅｓｓｒａｄｉａｌｄｉｓｔａｎｃｅｔ　Ｄｉｍｅｎｓｉｏｎｌｅｓｓｔｉｍｅｕ　Ｄｉｍｅｎｓｉｏｎｌｅｓｓａｘｉａｌｖｅｌｏｃ…     

甲醇与碳酸二甲酯共沸液的分离研究进展

综述了DMC-CH_3OH二元共沸液的各种分离方法。讨论了共沸精馏和萃取精馏的工艺流程。     

重油催化裂化反应技术的新进展

近十几年来，重油催化裂化技术作为主要的重质油轻质化手段得到了迅速发展，国内外围绕催化裂化装置的提升管反应器也开发了许多新技术。综述了重油催化裂化反应技术的新进展，并对新技术的开发进行了讨论。     

管环缝射线一次透照长度及分段次数的计算

介绍了管环缝射线透照方式，以及环缝单壁外透法和环缝双壁单影法100％射线透照检查一次透照长度及分段次数的计算。     

从废钼合金催化剂中提取钼等有价元素方法的研究

ＭｏＣｏＮｉ合金料首先氧化焙烧碱浸出，滤饼再加纯碱焙烧水浸出使钼与钴镍分离，最后用萃取法分离钴镍的工艺流程，对废钼合金催化剂进行了综合回收。采用该工艺流程和生产线分别生产出合格的工业级钼酸钠、氧化钴和氧化镍。     

Isometric Piecewise Polynomial Curves

The main preoccupations of research in computer-aided geometric design have been on shape-specification techniques for polynomial curves and surfaces, and on the continuity between segments or patches. When modelling with such techniques, curves and surfaces can be compressed or expanded arbitrarily. There has been relatively little work on interacting with direct spatial properties of curves and surfaces, such as their arc length or surface area. As a first step, we derive families of parametric piecewise polynomial curves that satisfy various positional and tangential constraints together with arc-length constraints. We call these curves isometric curves. A space curve is defined as a sequence of polynomial curve segments, each of which is defined by the familiar Hermite or Bézier constraints for cubic polynomials; as well, each segment is constrained to have a specified arc length. We demonstrate that this class of curves is attractive and stable. We also describe the numerical techniques used that are sufficient for achieving real time interaction with these curves on low-end workstations.