Phenomenological modeling of anisotropy induced by evolution of the dislocation structure on the macroscopic and microscopic scale

This work focuses on the modeling of the evolution of anisotropy induced by the development of the dislocation microstructure. A model formulated at the engineering scale in the context of classical metal plasticity and a model formulated in the context of crystal plasticity are presented. Images obtained by transmission-electron microscopy (TEM) show the influence of the strain path on the evolution of anisotropy for the case of two common materials used in sheet metal forming, DC06 and AA6016-T4. Both models are capable of accounting for the transient behavior observed after changes in loading path for fcc and bcc metals. The evolution of the internal variables of the models is correlated with the evolution of the dislocation structure observed by TEM investigations.     

Screening and confirmatory methods for the determination of melamine in cow’s milk and milk-based powdered infant formula: Validation and proficiency-tests of ELISA,HPLC-UV,GC-MS and LC-MS/MS

In recent years, two adulteration incidents concerning the addition of melamine, a small polar compound which is very rich in nitrogen, to pet food and infant formula products have occurred in China. These issues prompted private as well as governmental laboratories to develop methods for the analysis of melamine and related compounds in a wide variety of food products and ingredients. The development of methods was focussed on both, screening and quantification purposes, ranging from highly sophisticated chromatographic-mass spectrometric techniques to immuno-selective assays. The present work describes two screening and two confirmatory methods dedicated to the determination of melamine in cow’s milk and milk-based powdered infant formula. Screening methods are enzyme-linked immunosorbent assay (ELISA) and liquid chromatography coupled to ultraviolet detection, while confirmatory methods are based on gas and liquid chromatography coupled mass spectrometry techniques. Performance and validation data of the four methods, and results obtained in the frame of internal and European proficiency-tests are shown.     

Octane-1,3-diol and its derivatives from pear fruits

 In extracts obtained by liquid-liquid extraction from seven pear (Pyrus communis L.) cultivars, octane-1,3-diol, 5(Z)octene-1,3-diol, methyl 3-hydroxyoctanoate, ethyl 3-hydroxyoctanoate and ethyl 5(Z)-3-hydroxyoctenoate were identified by capillary gas chromatography-mass spectrometry. Evaluation of the absolute configuration was achieved by multidimensional gas chromatography, using a polar achiral column (DB-Wax) and a chiral main column (2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl-β-cyclodextrin/OV 1701). Comparison of retention times of synthesized optically enriched reference compounds with those of isolated diols and hydroxy esters revealed (R)-configurations for the 3-hydroxy derivatives, exhibiting enantiomeric excesses greater than 99%. In addition, (2S, 4R)- and (2R, 4R)-2-methyl-4-pentyl-1,3-dioxane as well as (2S, 4R)- and (2R, 4R)-2-methyl-4-(2′(Z)-pentenyl)-1,3-dioxane, products formed by acetaldehyde and octane-1,3-diol or 5(Z)-octene-1,3-diol, respectively, were detected in pear fruits. Received: 13 February 1997     

Salimyxins and Enhygrolides: Antibiotic,Sponge‐Related Metabolites from the Obligate Marine Myxobacterium Enhygromyxa salina

Unlike their terrestrial counterparts, marine myxobacteria are hardly investigated for their secondary metabolites. This study describes three new compounds ( 1 – 3 ), named salimyxins and enhygrolides, obtained from the obligate marine myxobacterium Enhygromyxa salina. These are the first natural products obtained from Enhygromyxa species. Their structures were elucidated by spectroscopic analysis, including NMR and CD spectroscopy. Enhygrolides are closely related to the nostoclides, which were initially isolated from a cyanobacterium of the genus Nostoc. The salimyxins, representing structurally most unusual degraded sterols, are close to identical to demethylincisterol from the sponge Homaxinella sp. Salimyxin B and enhygrolide A inhibit the growth of the Gram‐positive bacterium Arthrobacter cristallopoietes (MIC salimyxin B, 8 μg mL^?1; enhygrolide A, 4 μg mL^?1).     

Effect of Storage Time on Wax–Wax–Hydrolyzate Canola Oil Oleogels

In this study, two natural waxes, beeswax (BW) and sunflower wax (SFW), are combined with their hydrolyzed variants to deliberately alter the waxes’ composition. The properties of the produced oleogels with different wax inclusion levels (4%, 8%, 12%, and 16% w/w) are investigated after defined intervals (2 days, 7 days, 3 weeks, and 3 months). To do so, the gels are monitored via penetrometry, microscopy, and calorimetry. Although the gels do not show any significant difference during storage in the micrographs, the calorimetric and firmness data reveal meaningful results. The heat of dissolution increases in every system investigated, indicating post-crystallization processes. Due to different solubilities of wax components, the critical gelling concentration is determined and the solid wax content is retrieved to further address the structure efficiency (S.E.). It is demonstrated that although the quantity of solids over time increases, the scaffolding effectiveness decreases in most cases. Only SFW, most likely due to sintering, shows an increase in S.E. over the storage time. Identified synergistic effects in BW and hydrolyzate mixtures decrease with increasing storage time. This work aims to contribute to a better understanding of the behavior of wax-based oleogels upon storage. Practical Applications: Although much is known about the gel properties of wax-based oleogels at short-term, the behavior over the storage period remains largely unresolved. However, this behavior is immensely important for a real application in fast and slow moving consumer goods. After all, products should always have the same consumer-relevant properties when stored at variable time frames. This applies to both food and pharmaceutical products. Knowledge of the behavior of wax-based oleogels in terms of a time-dependent change can help to choose a targeted product design and ensure product quality and consumer satisfaction.     

Tailoring biosensors for Brazil: Detection of insecticides in foods

An acetylcholinesterase (AChE) B multisensor from Nippostrongylus brasiliensis (Nb) was developed, able to detect the most frequently used insecticides in Brazil. The objective was to establish a fast screening-out method, separating the negative samples from the positive ones. The four mutants, which together presented the widest sensitivity spectrum, were: F345A, M301A, W346V and W346A. The combination of these four mutants in a multienzyme biosensor array enabled the detection of 11 out of the 12 most important insecticides at concentrations below 10 μg/kg. The biosensor test was compared with traditional analysis methods, and validated with food samples previously analyzed. The storage stability revealed that the enzyme activity remained stable for 40 weeks; however the sensitivity decreased with time. The biosensor screened out samples with an analysis duration of about 2 h.     

Cultivation of Head and Neck Squamous Cell Carcinoma Cells with Wound Fluid Leads to Cisplatin Resistance via Epithelial-Mesenchymal Transition Induction

Locoregional recurrence is a major reason for therapy failure after surgical resection of head and neck squamous cell carcinoma (HNSCC). The physiological process of postoperative wound healing could potentially support the proliferation of remaining tumor cells. The aim of this study was to evaluate the influence of wound fluid (WF) on the cell cycle distribution and a potential induction of epithelial-mesenchymal transition (EMT). To verify this hypothesis, we incubated FaDu and HLaC78 cells with postoperative WF from patients after neck dissection. Cell viability in dependence of WF concentration and cisplatin was measured by flow cytometry. Cell cycle analysis was performed by flow cytometry and EMT-marker expression by rtPCR. WF showed high concentrations of interleukin (IL)-6, IL-8, IL-10, CCL2, MCP-1, EGF, angiogenin, and leptin. The cultivation of tumor cells with WF resulted in a significant increase in cell proliferation without affecting the cell cycle. In addition, there was a significant enhancement of the mesenchymal markers Snail 2 and vimentin, while the expression of the epithelial marker E-cadherin was significantly decreased. After cisplatin treatment, tumor cells incubated with WF showed a significantly higher resistance compared with the control group. The effect of cisplatin-resistance was dependent on the WF concentration. In summary, proinflammatory cytokines are predominantly found in WF. Furthermore, the results suggest that EMT can be induced by WF, which could be a possible mechanism for cisplatin resistance.     

Deville and Särndal’s calibration: revisiting a 25-years-old successful optimization problem

TEST - In 1992, in a famous paper, Deville and Särndal proposed the calibration method in order to adjust samples on known population totals. This paper had a very important impact in the...     

A generalized Weisfeiler-Lehman graph kernel

Machine Learning - After more than one decade, Weisfeiler-Lehman graph kernels are still among the most prevalent graph kernels due to their remarkable predictive performance and time complexity....