Pflanzeninhaltsstoffe—Vierte Mitteilung Untersuchung der Extraktstoffe vonPicea omorica

Zusammenfassung Aus dem Holz der Omorica-Fichte lie? sich mit Benzol 0,79% fettes ?l (bezogen auf darrtrockenes Holz) gewinnen. Durch Verseifung des ?les wurden 26,29% feste und 72,07% flüssige Fetts?uren erhalten. Nach der rhodanometrischen Analyse war die Zusammensetzung der flüssigen Fetts?ure: 38% ?ls?ure, 31,9% Linols?ure und 1,22% Linolens?ure. Der unverseifbare Anteil enthielt Cetylalkohol, wahrscheinlich Cerylalkohol und Sitosterin. Aus dem essigesterl?slichen Rohgerbstoff konnten auf chromatographischem Wege die Glucoside C₂₆H₃₃O₁₂ und C₃₀H₃₂O₁₄ isoliert werden, die bei der enzymatischen Spaltung mit Luitase-Extrakt ein kristallines Aglucon C₁₈H₁₆O₅ vom Fp. 208°C lieferten.

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Plant extractives—Part IV: Investigations on the extractives from picea omorica

Summary With the aid of benzole 0.79% greasy oil (related to ovendry wood) could be obtained from omorica pine. By saponification 26.29% of solid and 72.07% of liquid fatty acids were obtained from that oil. According to the rhodanometric analysis, the constituents of the liquid fatty acid were 38% oleic acid, 31.9% linol acid, and 1.22% linolene acid. The unsaponifiable portion contained cetyl alcohol, probably ceryl alcohol and sitosterine. Glucosides C₂₆H₃₃O₁₂ and C₃₀H₃₂O₁₄ could be isolated from the acetate-soluble raw tannin by chromatographic methods and their enzymatic splitting with luitase extract resulted in a crystalline aglucon C₁₈H₁₆O₅ with a melting point of 208°C.

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III. Mitteilung: R. Mayer u. K.-H. Starosta, Journ. f. Prakt. Chemie, im Druck.     

垃圾填埋场覆盖层现场试验及特性评价(英文)

填埋场覆盖系统由不同的土层组成,它们具有不同的性质和功能。覆盖层直接与大气和植被接触,因此土的含水率随季节和天气条件不断变化。冬天,土的饱和度增加。夏天,土的含水率减少,同时土中吸力增加。如果土中吸力达到某个极限值,将出现干缩裂缝。这时,粘土阻隔层的密封功能将受到损害。为了研究粘土覆盖系统的长期性状,我们进行了两个大规模现场试验。本文介绍第一批现场试验结果,包括水流量、土中吸力和温度的变化规律。重点介绍保护层(营养层)厚度对覆盖系统水平衡的影响。     

Finite elements on locally uniform meshes for convection–diffusion problems with boundary layers

The layer-adapted meshes used to achieve robust convergence results for problems with layers are not locally uniform. We discuss concepts of almost robust convergence and some realizations of locally-uniform meshes.     

Image registration based on lifting process: an application to digital subtraction radiography.

In this paper, a digital subtraction radiology scheme is presented based on a new method for the automatic registration of dental radiographs acquired with or without rigorous a priori standardization. The scheme is comprised of an automatic registration method and a subtraction process. The proposed registration method can be considered as an object-based registration method without imposing the prerequisite of image segmentation in order to detect the boundary of the objects of interest or the automatic detection of matching landmarks. This is achieved by augmenting the dimensionality of the problem from two-dimensional gray-level matching to three-dimensional surface matching using the process of lifting in combination with a surface-matching technique. The pseudo three-dimensional affine transformation that matches the lifted images incorporates advantageous characteristics including spatial alignment of the surfaces, anisotropic correction of brightness/contrast differences, and stable convergence of the similarity function to its optimal value. The performance of the proposed automatic registration method is assessed against a manual method based on the projective transformation. The qualitative and quantitative assessments of the experiments have shown advantageous performance of the proposed automatic registration method against the manual one. Finally, the proposed registration method has been further improved in terms of execution time by the implementation of a surface decimation process.     

Error estimation in a balanced norm for a convection-diffusion problem with two different boundary layers

The \(\varepsilon \) -weighted energy norm is the natural norm for singularly perturbed convection-diffusion problems with exponential layers. But, this norm is too weak to recognise features of characteristic layers. We present an error analysis in a differently weighted energy norm—a balanced norm—that overcomes this drawback.     

Hydrogels for Engineering of Perfusable Vascular Networks

Hydrogels are commonly used biomaterials for tissue engineering. With their high-water content, good biocompatibility and biodegradability they resemble the natural extracellular environment and have been widely used as scaffolds for 3D cell culture and studies of cell biology. The possible size of such hydrogel constructs with embedded cells is limited by the cellular demand for oxygen and nutrients. For the fabrication of large and complex tissue constructs, vascular structures become necessary within the hydrogels to supply the encapsulated cells. In this review, we discuss the types of hydrogels that are currently used for the fabrication of constructs with embedded vascular networks, the key properties of hydrogels needed for this purpose and current techniques to engineer perfusable vascular structures into these hydrogels. We then discuss directions for future research aimed at engineering of vascularized tissue for implantation.     

Gradient Recovery for Singularly Perturbed Boundary Value Problems I: One-Dimensional Convection-Diffusion

We consider a Galerkin finite element method that uses piecewise linears on a class of Shishkin-type meshes for a model singularly perturbed convection-diffusion problem. We pursue two approaches in constructing superconvergent approximations of the gradient. The first approach uses superconvergence points for the derivative, while the second one combines the consistency of a recovery operator with the superconvergence property of an interpolant. Numerical experiments support our theoretical results. Received November 12, 1999; revised September 9, 2000     

应用FEM数值模拟优化连铸结晶器

研究了应用FEM数值模拟优化连铸过程和结晶器。结晶器的优化设计通常从连铸过程中的稳态模拟开始。根据理论数据，使用边界条件来确保计算过程尽可能地接近实际；物理特性的使用以及在连铸过程中记录下的测量数据使计算得到调整并适应于连铸实际工作条件。应用这些初期的基础计算，可进一步地模拟冷却参数、结晶器材质和镀层改变对结晶器所造成的影响。使用FEM软件计算，除了可以优化连铸过程，还可以提高结晶器寿命，同时提高连铸产品的质量。在考虑结晶器热力学问题的同时，还应考虑使用为确定母材和钢坯应力的热结构分析法，以及为模拟熔化流动和冷却水设计的CFD软件(计算流体动力学)和FSI软件(流体结构相互作用模拟)，这些分析方法得到了越来越广泛的应用。     

Estimation of Dislocation Density in Cold-Rolled Commercially Pure Titanium by Using Synchrotron Diffraction

Cold rolling (CR) leads to a heavy changes in the crystallographic texture and microstructure, especially crystal defects, such as dislocations, and stacking faults increase. The microstructure evolution in commercially pure titanium (cp-Ti) deformed by CR at the room temperature was determined by using the synchrotron peak profile analysis of full width at half maximum (FWHM). The computer program ANIZC has been used for the calculation of diffraction contrast factors of dislocations in elastically anisotropic hexagonal crystals. The dislocation density has a minimum value at 40 pct reduction. The increase of the dislocation density at higher deformation levels is caused by the nucleation of new generation of dislocations from the crystallite grain boundaries. The high-cycle fatigue strength (HCF) has a maximum value at 80 pct reduction and it has a minimum value at 40 pct reduction in the commercially pure titanium.