吸水性对防污涂料性能影响的研究

由于中国的许多船厂位于淡水流域,淡水浸泡对防污涂料的影响正引起人们越来越多的关注。本研究中,选取了4种基于丙烯酸硅烷技术和6种基于离子交换技术的防污涂料,比较了在海水和淡水里的吸水性能。为了便于确定成膜树脂与相应涂料吸水性能之间的相关性,将成膜树脂从涂料中分离出来进行研究。     

High‐Speed,Low‐Voltage,and Environmentally Stable Operation of Electrochemically Gated Zinc Oxide Nanowire Field‐Effect Transistors

Single‐crystal, 1D nanostructures are well known for their high mobility electronic transport properties. Oxide‐nanowire field‐effect transistors (FETs) offer both high optical transparency and large mechanical conformability which are essential for flexible and transparent display applications. Whereas the “on‐currents” achieved with nanowire channel transistors are already sufficient to drive active matrix organic light emitting diode (AMOLED) displays; it is shown here that incorporation of electrochemical‐gating (EG) to nanowire electronics reduces the operation voltage to ≤2 V. This opens up new possibilities of realizing flexible, portable, transparent displays that are powered by thin film batteries. A composite solid polymer electrolyte (CSPE) is used to obtain all‐solid‐state FETs with outstanding performance; the field‐effect mobility, on/off current ratio, transconductance, and subthreshold slope of a typical ZnO single‐nanowire transistor are 62 cm²/Vs, 10⁷, 155 μS/μm and 115 mV/dec, respectively. Practical use of such electrochemically‐gated field‐effect transistor (EG FET) devices is supported by their long‐term stability in air. Moreover, due to the good conductivity (≈10^?2 S/cm) of the CSPE, sufficiently high switching speed of such EG FETs is attainable; a cut‐off frequency in excess of 100 kHz is measured for in‐plane FETs with large gate‐channel distance of >10 μm. Consequently, operation speeds above MHz can be envisaged for top‐gate transistor geometries with insulator thicknesses of a few hundreds of nanometers. The solid polymer electrolyte developed in this study has great potential in future device fabrication using all‐solution processed and high throughput techniques.     

Fluorinated Polymer Yields High Organic Solar Cell Performance for a Wide Range of Morphologies

Device performance is recognized to be generally sensitive to morphology in bulk heterojunction solar cells. Through the use of quantitative morphological measurements, it is demonstrated that devices based on benzodithiophene and fluorinated benzotriazole moieties constitute an exception to this design rule and exhibit a range of morphologies that yield similar high performance. In particular, the fill factor (FF) remains above 65% even with factor of two changes in domain size and factor of two changes in relative domain purity. Devices with active layer thicknesses of 250 nm are employed, which are capable of increasing optical absorption to produce high photocurrent. The general insensitivity to both morphology and thickness is likely related to the measured low equilibrium miscibility of fullerene in the polymer of 3‐4%. The materials and processes investigated therefore provide insights into functional material design that yield increased processing latitude and may be more amenable to roll‐to‐roll processing.     

Dust‐induced shading on photovoltaic modules

The effect of dust on photovoltaic modules is investigated with respect to concentration and spectral transmittance. Samples were collected in the form of raw dust as well as accumulated dust on exposed sheets of glass at different tilt angles. Spectral transmittance of the samples was determined. Transmittance variation between top, middle and bottom was identified for samples collected at different inclinations, where the worst case was seen at a tilt angle of 30^o with a non‐uniformity of 4.4% in comparison with 0.2% for the 90° tilt. The measured data showed a decrease in transmittance at wavelengths <570 nm. Integrating this with measured spectral responses of different technologies demonstrates that wide band‐gap thin‐film technologies are affected more than, for example crystalline silicon technologies. The worst case is amorphous silicon, where a 33% reduction in photocurrent is predicted for a dust concentration of 4.25 mg/cm². Similarly, crystalline silicon and CIGS technologies are predicted to be less affected, with 28.6% and 28.5% reductions in photocurrent, respectively. The same procedure was repeated with varying Air Mass (AM), tilt angle and dust concentration values to produce a soiling ratio table for different technologies under different AM, tilt angle and dust concentration values. Copyright © 2012 John Wiley & Sons, Ltd.     

The yeast Wickerhamomyces anomalus AS1 secretes a multifunctional exo‐β‐1,3‐glucanase with implications for winemaking

A multifunctional exo‐β‐1,3‐glucanase (WaExg2) was purified from the culture supernatant of the yeast Wickerhamomyces anomalus AS1. The enzyme was identified by mass spectroscopic analysis of tryptic peptide fragments and the encoding gene WaEXG2 was sequenced. The latter codes for a protein of 427 amino acids, beginning with a probable signal peptide (17 aa) for secretion. The mature protein has a molecular mass of 47 456 Da with a calculated pI of 4.84. The somewhat higher mass of the protein in SDS–PAGE might be due to bound carbohydrates. Presumptive disulphide bridges confer a high compactness to the molecule. This explains the apparent smaller molecular mass (35 kDa) of the native enzyme determined by electrophoresis, whereas the unfolded form is consistent with the theoretical mass. Enzymatic hydrolysis of selected glycosides and glycans by WaExg2 was proved by TLC analysis of cleavage products. Glucose was detected as the sole hydrolysis product from laminarin, underlining that the enzyme acts as an exoglucanase. In addition, the enzyme efficiently hydrolysed small β‐linked glycosides (arbutin, esculin, polydatin, salicin) and disaccharides (cellobiose, gentiobiose). WaExg2 was active under typical wine‐related conditions, such as low pH (3.5–4.0), high sugar concentrations (up to 20% w/v), high ethanol concentrations (10–15% v/v), presence of sulphites (up to 2 mm ) and various cations. Therefore, the characterized enzyme might have multiple uses in winemaking, to increase concentrations of sensory and bioactive compounds by splitting glycosylated precursors or to reduce viscosity by hydrolysis of glycan slimes. Copyright © 2014 John Wiley & Sons, Ltd.     

Zur Frage der Entstehung von Nitrosaminen bei der Reaktion von Monosacchariden mit Aminos?uren (Maillard-Reaktion) in Gegenwart von Natriumnitrit 2. Mitteilung

Zusammenfassung Drei Modell-Gemisched-Glucose/dl-Alanin,d-Glucose/l-Lysin undd-Glucose/l-Glutaminsäure wurden unter Zugabe von Natriumnitrit unter Maillard-Bedingungen gebräunt. Die Zugabe von Natriumnitrit erfolgte vor und nach der Bräunung. Im letzteren Fall schloß sich eine kurze Nachbräunung an. Die Reaktionsbedingungen — pH-Wert und Bräunungstemperaturen — wurden variiert. Die Analyse der alkalibeständigen wasserdampfflüchtigen Maillard-Produkte erfolgte durch GC und GC/MS-Analyse. Bei den identifizierten Produkten handelt es sich um alkylierte Pyrazine, Furan- und Pyridin-Derivate. Nitrosopiperidin wurde aus dem Bräunungsansatzd-Glucose/l-Lysin (Nitritzugabe nach der Bräunung) massenspektrometrisch nachgewiesen.Die Änderung des pH-Wertes um eine Einheit, sowie die Änderung der Bräunungstemperatur innerhalb des Temperaturbereiches 100–150° C haben auf die qualitative Zusammensetzung der flüchtigen Maillard-Produkte eines betrachteten Modell-Gemisches keinen Einfluß. Ein geringer Unterschied wird hinsichtlich der quantitativen Zusammensetzung beobachtet.

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The problem of nitrosamine formation by the reaction of monosaccharides with aminoacids (maillard-reaction) in the presence of sodiumnitrite. 2.

Summary Three model mixturesd-glucose/dl-alanine,d-glucose/l-lysine andd-glucose/l-glutamic acid were browned under Maillard conditions with addition of sodium nitrite. The nitrite was added either before or after the browning reaction. When the nitrite was applied after the browning reaction, a second browning was performed.Reaction conditions-pH-values and browning temperatures — were changed. By GC and GC/MS analysis of alkaline stable volatile Maillard products formation of alkylated pyrazines, furan and pyridine derivatives was confirmed. Thus nitrosopiperidine was detected in subsequent addition of sodiumnitrite after browningd-glucose/l-lysine mixtures.The one unit change of the pH-values and the browning temperature within the range of 100–150° C do not have influence on the qualitative composition of the volatile Maillard products for a certain model mixture. Slight differences were established only in the quantitative composition.

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1. Mitt. Z. Lebensm. Unters.-Forsch. 145, 76–84 (1971)     

Naturwissenschaftliche Untersuchungsergebnisse an Gebrauchskeramikproben vom mittelbronzezeitlichen Arbeits- und Siedlungsplatz Schlosser/KG Schwarzenbach/OG Trieben

A chemical and mineralogical analysis was made at the chair of Ceramics, Montanuniversit?t Leoben, of six items of pottery chosen from the objects yielded by the mining archaeological excavations (2000) at the mid-bronze age working site and settlement "Schlosser", cadastral community of Schwarzenbach, parish of Trieben, Austria. In order to distinguish between fine and ordinary (coarse) pottery, a visual assessment of the maximum grain was applied. In pottery making, the most common nonplastic materials used are quartz and feldspar as well as feldspar substitutes; in two cases considerable quantities of muscovite were found. The fine ceramic samples have a maximum grain size of up to 2 mm, for the ordinary ceramic samples it is over 2 mm. The number of large grains in the fine ceramics is up to 3.8/cm², while the ordinary ceramics show up to 8.4 large grains /cm². This is an indication that in the manufacture of fine ceramics a grogging strategy was employed deliberately that differed from the one for ordinary ceramics. It is proved that the distribution of large grains was a quality criterion in the ceramics production at this site. The above mentioned flux stones as well as traces of minerals found in the pottery samples correspond to a paragenesis that is typical of the crystalline phase. It is therefore likely that the raw materials came from an area not far from the find location of the pottery in the Palten Valley. Comparisons with the results of tests performed on samples of pottery from the smelting site Versunkene Kirche corroborate this thesis.