Die Ausbildung der Seitenflächen beim Warmwalzen mit freier Breitung

Überprüfung der im Betrieb gewonnenen Ergebnisse auf einem Versuchswalzwerk. Ausbauchung oder Einschnürung bei quadratischen Ausgangsabmessungen in Abhängigkeit von der Anstichhöhe. Vergleich mit Rechenwerten einiger Breitungsformeln. Abhängigkeit von der Stichabnahme bei konstantem Ausgangsquerschnitt. Größe der auf die Stichabnahme bezogenen Ausbauchung oder Einschnürung als Funktion des Verhältnisses l_d/h₀. Einfluß der Waktemperatur und des Gefügezustandes. Einfluß des Ausgangsquerschnittes bzw. Seitenverhältnisses b₀/h₀ auf den Übergang von der Ausbauchung zur Einschnürung. Einfluß der Stichanzahl. Vergleich mit Betriebsversuchen. Übertragbarkeit der Ergebnisse bei Beachtung geometrischer Ähnlichkeit.     

文化景观维护视野下德国历史性文化景观的两种方法论： 清单盘点与空间区划

中欧国家当前面临诸多发展问题,诸如地区差异化、农业土地面积矛盾加剧、高密度区域土壤退化及多样性丧失等,引发了学术界的关注。从20世纪90年代开始,德语背景下的"文化景观维护"概念建立。利用历史地理学、考古学与遗产保护学以及空间与区域规划等学科的综合方法,对国土和区域空间内的文化景观进行分析和研究。文化景观维护概念以"永恒的圆环"理论模型体现,并分为分析与评价、保护与阐释、规划与管理3个主要步骤。基于此基本概念,文化景观维护大致分为2个研究方法范本:清单盘点与空间区划。范本一:历史性文化景观的对象清单盘点,就是对一定的限定区域内的文化景观要素和结构的系统化收集分类和评价方法。又分两种不同类型:Gunzelmann的复杂型"历史性文化景观"的分析法与Burggraaff和Kleefeld的"文化景观物质分析"法。范本二:文化景观的区域化,旨在从专家角度对历史性文化景观进行标记、注释、分类和简要的特征化。又细分为类型化和个性化2个类型,并结合案例说明。最后指出:对两种研究方法的应用,不仅要客观地分析各种因素,而且还要考证在特定政治背景下的适用性。     

Pressure‐Sensitive Adhesive Blend Films for Low‐Tack Applications

Polymer blend films consisting of a tacky and a nonadhesive component are promising candidates for low‐tack applications. Immiscibility of both components results in a phase separation process yielding a tacky matrix with glassy objects embedded. The influence of the blending ratio of the components poly(n‐butyl acrylate) (PnBA) and polystyrene (PS) is addressed. The mechanical information resulting from the tack test shows the possibility of varying the bonding strength of the PSA blend over a wide range. The macroscopic and microscopic structural characterization with optical microscopy and ultrasmall angle X‐ray scattering (USAXS) shows that the blend PnBA/PS exhibits similarities to common filler systems as well as deviates regarding installed structures. Due to the large domain size on a microscopic level, only the tacky component, PnBA, defines the adhesive behavior. The nonadhesive component limits the contact area between the adhesive and the substrate.

     

Cocoa polyphenols are absorbed in Caco-2 cell model of intestinal epithelium

Cocoa is an abundant source of polyphenols, mainly flavan-3-ol monomers and polymers. In the literature, there are contradictory data on the absorption limit of procyanidins in humans. In our study, the Caco-2 cell model of intestinal epithelium was used to determine the absorption and secretion of cocoa flavan-3-ols. Three compounds: (+)-catechin, (-)-epicatechin and procyanidin B2 were detected and quantified at the receiver side of Caco-2 monolayer after 2h transport experiment. The obtained results of apparent permeability coefficient suggest paracellular route of transport of investigated compounds. Additionally, the results suggest that compounds of cocoa powder purified extract are able to affect tight junction functioning.     

On-line carbon balance of yeast fermentations using miniaturized optical sensors

Monitoring of microbiological processes using optical sensors and spectrometers has gained in importance over the past few years due to its advantage in enabling non-invasive on-line analysis. Near-infrared (NIR) and mid-infrared (MIR) spectrometer set-ups in combination with multivariate calibrations have already been successfully employed for the simultaneous determination of different metabolites in microbiological processes. Photometric sensors, in addition to their low price compared to spectrometer set-ups, have the advantage of being compact and are easy to calibrate and operate. In this work, the detection of ethanol and CO(2) in the exhaust gas during aerobic yeast fermentation was performed by two photometric gas analyzers, and dry yeast biomass was monitored using a fiber optic backscatter set-up. The optical sensors could be easily fitted to the bioreactor and exhibited high robustness during measuring. The ethanol content of the fermentation broth was monitored on-line by measuring the ethanol concentration in the fermentation exhaust and applying a conversion factor. The vapor/liquid equilibrium and the associated conversion factor strongly depend on the process parameter temperature but not on aeration and stirring rate. Dry yeast biomass was determined in-line by a backscattering signal applying a linear calibration. An on-line balance with a recovery rate of 95-97% for carbon was achieved with the use of three optical sensors (two infrared gas analyzers and one fiber optic backscatter set-up).