Synthesis ofGEM-dibromocyclopropanoid fatty esters using phenyl (tribromomethyl) mercury

Thegem-dibromocyclopropanation of naturally occurring unsaturated hydroxy fatty esters, methyl ricinoleate (I) and methyl isoricinoleate (II), has been undertaken to provide compounds which might have potential utility. Phenyl(tribromomethyl)mercury reacts only with the carbon-carbon double bond of each substrate, leaving the OH group intact. The product, methyl 9,10-dibromomethylene-12-hydroxyoctadecanoate (III) and methyl 12,13-dibromomethylene-9-hydroxyoctadecanoate (IV), obtained from I and II, respectively, were characterized by elemental, infrared (IR) and nuclear magnetic resonance (NMR) analyses.     

The trap depth in evaporated polypropylene from measurements of thermally stimulated currents

The occurrence of thermally stimulated currents in thin evaporated films of polypropylene was demonstrated and an analysis of the curves gave an electron trap depth of 0.33 eV in this material.     

Die Instandsetzung der Old White Nile Bridge in Khartoum/Sudan

Die Old White Nile und die Old Blue Nile Bridge waren die ersten beiden Brücken überhaupt, die in Khartoum, der Hauptstadt des Sudan über den Nil führten. Sie wurden von der Britischen Baufirma Dorman Long Ltd. in den Jahren 1908 und 1928 gebaut und erfüllen bis heute in nahezu unveränderter Form ihren Dienst. Sie stellen damit funktionstüchtige, ingenieurtechnische Denkmale dar und zeugen von der außergewöhnlichen Ingenieurleistung, die hier unter schwierigen klimatischen und technologischen Bedingung erbracht wurde. Der folgende Beitrag befasst sich mit der Instandsetzung der Old White Nile Bridge, welche im Zeitraum von 2004 bis 2007 durchgeführt wurde. Die Schüßler‐Plan Ingenieurgesellschaft wurde von der Brückenbauverwaltung der Stadt Khartoum mit verschiedenen Untersuchungen im Zusammenhang mit dem Sanierungskonzept betraut. Der Aufsatz befasst sich neben einem historischen Rückblick mit der Entscheidung, ob ein Auswechseln der 80 Jahre alten, in ihrer Funktion stark eingeschränkten Brückenlager aus statischer Sicht notwendig ist oder diese am Bauwerk belassen werden können. Auch für die Old Blue Nile Bridge ist in den kommenden Jahren eine grundlegende Instandsetzung vorgesehen. Da die Konstruktion vergleichbar ist, können die bei der Old White Nile Bridge gewonnenen Erkenntnisse hierbei einen wertvollen Beitrag leisten. Rehabilitation of old steel bridges over the Nile in Khartoum/Sudan. The Old White Nile Bridge and the Old Blue Nile Bridge were the first bridges ever to cross the Nile at Khartoum – Capital of the Sudan. They were build In 1928 and 1908 by the British Company Dorman Long Ltd. and till today service the traffic in Khartoum in their since then unchanged form. They represent as such a functional technical monument and an attest of the unusual engineering achievement, which was realised under the most extreme climatic and technological conditions. The following report is about the rehabilitation of the Old White Nile Bridge, which was carried out from 2004 till 2007. The Schüßler‐Plan Ingenieurgesellschaft was contracted by the Bridge Department of the State of Khartoum with several analysis related with the rehabilitation concept. The report starts with an historic review of the bridge and continuous with the decision weather it is statically necessary to exchange the nearly 80 year old bearings that are strongly hindered in their function, or weather they could be left unchanged. For the Blue Nile Bridge also, a complete rehabilitation is planned in the near future. Since the two bridge structures are comparable, the knowledge collected at the Old White Nile Bridge could be of great advantage for the Blue Nile rehabilitation.     

A general model for air-side proton exchange membrane fuel cell contamination

This paper presents a general model for air-side feed stream contamination that has the capability of simulating both transient and steady-state performance of a PEM fuel cell in the presence of air-side feed stream impurities. The model is developed based on the oxygen reduction reaction mechanism, contaminant surface adsorption/desorption, and electrochemical reaction kinetics. The model is then applied to the study of air-side toluene contamination. Experimental data for toluene contamination at four current densities (0.2, 0.5, 0.75 and 1.0 A cm⁻²) and three contamination levels (1, 5 and 10 ppm) were used to validate the model. In addition, it is expected that, with parameter adjustment, this model can also be used to predict performance degradation caused by other air impurities such as nitrogen oxides (NO_x) and sulfur oxides (SO_x).     

A novel technique for the measurement of liquid viscosity

A novel technique for the measurement of liquid viscosity is presented. In this technique, a disk was driven by a constant speed dc shunt motor in the test liquid. The change in the motor current measured the viscosity. The change in motor current was measured using an instrumentation amplifier and the viscosity of the liquid was measured in terms of output voltage. The temperature of the liquid was controlled using a peltier cooler/heater and was measured using an AD590 two-terminal integrated circuit temperature sensor. The viscosity of vegetable oils (groundnut, palm, sunflower, coconut) in the temperature range from 20 °C to 60 °C were determined. The results thus found were similar to the results obtained from a Redwood viscometer. This technique is useful to measure viscosity of liquids.     

Chapatti sensory and textural quality in relation to whole meal flour and dough characteristics

Food Science and Biotechnology - Current study was designed to evaluate sensory and textural quality characteristics of chapatti, a commonly consumed flat bread in South-Asia in relation to flour...     

Detection of olive oil adulteration with some plant oils by GLC analysis of sterols using polar column

A new method was developed to determine the presence of some refined vegetable oils in olive oil based on the sum of campesterol and stigmasterol percentages. Model systems of corn, soybean, sunflower and cotton seed oils in olive oil at levels of 5%, 10% and 20% were prepared. The unsaponifiables of these model systems were analysed by GLC using polar column with high thermal stability. An olive oil authenticity factor based on the summation of campesterol and stigmasterol percentages was established as an indicator of olive oil adulteration with vegetable oils. The results indicate the possibility to detect the presence as little as 5% of these plant oils in olive oil.