Evidence for the Aging of Wax Deposits in Crude Oils by Ostwald Ripening

The ageing of wax deposits is known to occur in paraffinic waxes forming in pipelines and storage tanks. It is characterized by a hardening of the deposit and an increase in paraffin content. A mechanism for the ageing of deposits, based on diffusion caused by temperature-concentration gradients within the wax, has been previously proposed. This work presents evidence indicating Ostwald Ripening to be another ageing mechanism of wax deposits. Rheology of paraffinic crudes, kept isothermally at temperatures in the neighborhood of the pour point, shows a kinetic of hardening of the oil samples. The X-ray diffraction and Cross Polar Microscopy indicate this phenomenon to be caused by an increase of the crystallites size with time. The DSC measurements support the idea that recrystallization takes place in the wax sample. The evidence gathered shows another ageing mechanism based on the recryztallization of the paraffins, such as Ostwald Ripening, to be responsible for the ageing of wax deposits besides the diffusion mechanism previously proposed     

Placing underground pressure pipes by machine

A machine system has been patented in the German Democratic Republic which links a digger and pipe placing unit for installing and connecting PVC pressure pipes underground with the minimum of soil displacement. The authors are engineers working at the Academy of Building, Institute for Civil Engineering, Leipzig.     

4-Methylimidazol in Caramel und caramelgef?rbten Lebensmitteln

Zusammenfassung Es wird eine spezifische und kochempfindliche Methode zur Bestimmung von 4-Methylimidazol (4-MeI) in Caramel und caramelgefärbten Lebensmitteln beschrieben. Nach der Extraktion wird 4-MeI gaschromatographisch mit einem stickstoffspezifischen elektrochemischen Detektor (Hall) bestimmt. Als weniger spezifische Alternative kann ein thermoionischer Detektor eingesetzt werden. Bei Zusätzen von 5–200 mg 4-MeI/kg Karamel beträgt die Wiederfindungsrate 90–94%.Die Nachweisgrenze der Methode liegt unterhalb 0,1 mg 4-MeI/kg Caramel; in karamelgefärbten Lebensmitteln können weniger als 0,01 mg/kg nachgewiesen werden.

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4-methylimidazole in caramel and caramel-colored foodsDetermination by gas-liquid-chromatography with nitrogen-specific detectors

Summary A specific and highly sensitive method for the determination of 4-methylimidazole (4-MeI) in caramel and caramel-colored foods is described. After extraction the amount of 4-MeI is determined by gas-liquid chromatography with a nitrogen-specific electrochemical detector (Hall). As a less specific alternative a thermoionic detector can be used. With additions in the range of 5–200 mg 4-MeI/kg caramel, recoveries of 90–94% are obtained.The limit of detection is <0.1 mg 4-Mel/kg caramel; in caramel-colored foods less than 0.01 mg/kg can be detected.

     

Structural similarity-based object tracking in multimodality surveillance videos

This paper addresses the problem of object tracking in video sequences for surveillance applications by using a recently proposed structural similarity-based image distance measure. Multimodality surveillance videos pose specific challenges to tracking algorithms, due to, for example, low or variable light conditions and the presence of spurious or camouflaged objects. These factors often cause undesired luminance and contrast variations in videos produced by infrared sensors (due to varying thermal conditions) and visible sensors (e.g., the object entering shadowy areas). Commonly used colour and edge histogram-based trackers often fail in such conditions. In contrast, the structural similarity measure reflects the distance between two video frames by jointly comparing their luminance, contrast and spatial characteristics and is sensitive to relative rather than absolute changes in the video frame. In this work, we show that the performance of a particle filter tracker is improved significantly when the structural similarity-based distance is applied instead of the conventional Bhattacharyya histogram-based distance. Extensive evaluation of the proposed algorithm is presented together with comparisons with colour, edge and mean-shift trackers using real-world surveillance video sequences from multimodal (infrared and visible) cameras.     

Protein haze formation in wines revisited. The stabilising effect of organic acids

The effect on the wine protein haze potential of five organic acids commonly encountered in wines (l(+)-tartaric, l(−)-malic, citric, succinic and gluconic acids) was assessed. All five acids, tested at 20 mM, reduced dramatically the haze potential of proteins, either in wine or dissolved in water, throughout the range of pH values typical of wines (i.e., from 2.8 through 3.8). Subtle differences among the acid effects did not correlate with the number of their carboxyl groups, but were attributed to electrostatic interactions that depend upon the acid pK_a values, the protein pI values and the medium pH. These results invalidate or question the validity of all experiments on wine proteins involving wine model solutions containing organic acids. Overall, the results obtained in the present work clearly indicate that organic acids with a common occurrence in wines exhibit a stabilising effect upon the haze potential of the wine proteins.     

Mechanical characteristics of artificial cell walls

Artificial plant cell walls were produced from bacterial cellulose and cell wall constituents. The artificial cell walls were stored at low, medium and high relative humidity, and then subjected to micro-mechanical tests. From chemical composition and microstructure analysis it was found that, among all artificial cell wall materials produced, the most representative analogue of natural apple cell wall was based on bacterial cellulose supplemented with xyloglucan and pectin. Uniaxial tensile tests revealed that the different cell wall materials differed in their mechanical properties; increasing the humidity during storage resulted in a decrease in the value of the secant modulus. The cell wall model material obtained may be used for the simulation of the effect of external factors on the physical and chemical properties of cell walls.