Pro- und Antioxydantien auf dem Fettgebiet XX: Die Lipoide der Hefezellen in verschiedenen Wachstumsphasen

Pro- and Antioxidants in The Field of Fats XX: Lipids of the Yeast Cells in Different Stages to Growth By the example of different cultures of saccharomyces cerevisiae it is shown that the amount of lipids of the same and their composition depend on the age and the growth of the yeast cells. Under anaerobic conditions, the lipids of different classes are diminished and they are converted to physiologically less active compounds e. g. sterols into squalene. The presence of oxygen is necessary for the biosynthesis of phospholipids and sterol esters also.     

Construction and analysis of educational tests using abductive machine learning

Recent advances in educational technologies and the wide-spread use of computers in schools have fueled innovations in test construction and analysis. As the measurement accuracy of a test depends on the quality of the items it includes, item selection procedures play a central role in this process. Mathematical programming and the item response theory (IRT) are often used in automating this task. However, when the item bank is very large, the number of item combinations increases exponentially and item selection becomes more tedious. To alleviate the computational complexity, researchers have previously applied heuristic search and machine learning approaches, including neural networks, to solve similar problems. This paper proposes a novel approach that uses abductive network modeling to automatically identify the most-informative subset of test items that can be used to effectively assess the examinees without seriously degrading accuracy. Abductive machine learning automatically selects only effective model inputs and builds an optimal network model of polynomial functional nodes that minimizes a predicted squared error criterion. Using a training dataset of 1500 cases (examinees) and 45 test items, the proposed approach automatically selected only 12 items which classified an evaluation population of 500 cases with 91% accuracy. Performance is examined for various levels of model complexity and compared with that of statistical IRT-based techniques. Results indicate that the proposed approach significantly reduces the number of test items required while maintaining acceptable test quality.     

Electrospun highly corrosion-resistant polystyrene–nickel oxide superhydrophobic nanocomposite coating

A key challenge in producing superhydrophobic coatings (SHC) is to tailor the surface morphology on the micro-nanometer scale. In this work, a feasible and straightforward route was employed to manufacture polystyrene/nickel oxide (PSN) nanocomposite superhydrophobic coatings on aluminum alloys to mitigate their corrosion in a saline environment. Different techniques were employed to explore the influence of the addition of NiO nanoparticles to the as-prepared coatings. PSN-2 composite with?~?4.3 wt% of NiO exhibited the highest water contact angle (WCA) of 155°?±?2 and contact angle hysteresis (CAH) of 5°.

Graphic abstract

EIS Nyquist plots of 3 g of electrospun polystyrene coatings (a) without and with (b) 0.1, (c) 0.15, and (d) 0.2 g of NiO.

     

Fractional Order Oscillator Design Based on Two-Port Network

In this paper, a general analysis of the generation for all possible fractional order oscillators based on two-port network is presented. Three different two-port network classifications are used with three external single impedances, where two are fractional order capacitors and a resistor. Three possible impedance combinations for each classification are investigated, which give nine possible oscillators. The characteristic equation, oscillation frequency and condition for each presented topology are derived in terms of the transmission matrix elements and the fractional order parameters \(\alpha \) and \(\beta \). Mapping between some cases is also illustrated based on similarity in the characteristic equation. The use of fractional order elements \(\alpha \) and \(\beta \) adds extra degrees of freedom, which increases the design flexibility and frequency band, and provides extra constraints on the phase difference. Study of four different active elements, such as voltage-controlled current source, gyrator, op-amp-based network, and second-generation current-conveyor-based network, serve as a two-port network is presented. The general analytical formulas of the oscillation frequency and condition as well as the phase difference between the two oscillatory outputs are derived and summarized in tables for each designed oscillator network. A comparison between fractional order oscillators with their integer order counterparts is also illustrated where some designs cannot work in the integer case. Numerical Spice simulations and experimental results are given to validate the presented analysis.     

Thermal cracking combined with supercritical fluid extraction of Jordanian oil shale

In this work, supercritical extraction of Jordanian oil shale was investigated experimentally using a batch autoclave device. Operating conditions such as solvent type, mixing time, temperature, pressure, and particle size effects on oil recovery from oil shale have been studied. The results indicated that oil yield increases with the increase of pressure and temperature. The maximum extract yields of 15 and 16 wt% were obtained at 42 bars and 318°C with toluene for El-Lajjun and Sultani shales, respectively. Supercritical fluid extraction (SFE) has shown to be an efficient technique since the extracted yield was 55% more than the yield obtained using the classical Fischer Assay retorting process.     

Enhancement of the electrical performance of poly(vinyl) alcohol by doping with chlorophyll and gamma irradiation

The electrical properties of poly(vinyl) alcohol (PVA) have been improved pronouncedly by doping with chlorophyll (Chl) and gamma irradiation. PVA/Chl films have been prepared and irradiated with γ-rays at dose levels of 10, 20, 30, 50, 70, 100, 150, 200 and 250 kGy. The crystalline and chemical structures of the samples have been studied using XRD and FTIR techniques. Also, the direct current electrical conductivity and the dielectric constant and loss have been determined for the proposed samples before and after gamma exposure. It is clearly shown that the electrical conductivity of PVA films was increased two orders of magnitude due to chlorophyll doping and about fifteen times due to gamma irradiation. Considering the dielectric constant and loss, their values were shown to increase significantly due to PVA doping with chlorophyll. The obtained results can be attributed to the existence of the conducting Mg atom, as well as, the conjugated double bonds in the chlorophyll. Moreover, the gamma irradiation of PVA/Chl, over 50 kGy, improves also this electrical performance. Therefore, the study suggests the possibility of the utilization of the gamma irradiated PVA/Chl films in different electronic applications.     

Bending of cross-ply laminated plates resting on elastic foundations under thermo-mechanical loading

This article investigates the bending response of an orthotropic rectangular plate resting on two-parameter elastic foundations under thermo-mechanical loadings. Analytical solutions for deflection and stresses are investigated by using an unified shear deformation plate theory. The present plate theory enables the trial and testing of different through-the-thickness transverse shear-deformation distributions and, among them, strain distributions that do not involve the undesirable implications of the transverse shear correction factors. The governing equations that include the interaction between the plate and the foundations are obtained. Numerical results are presented to demonstrate the behavior of the system. The influences of aspect ratio, side-to-thickness ratio, thermal expansion coefficients ratio and stacking sequence on the thermally induced response are studied.     

Use of some natural oils as crude pipeline corrosion inhibitors in sodium hydroxide solutions

Galvanostatic and potentiodynamic anode polarization methods were used to study the inhibiting effect of parsley, lettuce, and radish oils on corrosion of carbon steel L-52, used in Egypt in manufacturing pipelines, in 0.5 M NaOH solution. This effect increases with an increase in the concentration of these oils, which is due to adsorption of the basic components of the oils on the surface of the steel. The adsorption process is described by a Langmuir isotherm. It was found that incorporation of chloride ions in the 0.5 M solution of NaOH accelerates pitting corrosion of the steel as a result of moving the pitting potential toward more negative values. The investigated oils added to the solutions containing chloride ions protect steel from pitting corrosion.     

Simultaneous design of a product family and its related supply chain using a Tabu Search algorithm

Product family design is currently facing a multitude of challenges, the main problem stemming from the diversity offered to consumers. To design a product family, designers have to define an efficient bill of materials which ensures product assembly within a predefined length of time in order to satisfy the synchronised delivery principle. In addition, the modules used to assemble the finished products have to be competitive in terms of logistical costs. The ability to anticipate the constraints associated with the production process and with transportation is consequently of great interest. In this paper, we focus on the process of identifying a set of modules to be used in the assembly of the finished product. The objective is to define the bill of materials for each product from the modules belonging to that set, and to assign these modules to distant facilities where they will be manufactured and then shipped to a nearby facility for final assembly within a specific time. We use a set partitioning formulations to represent the problem, and solve it by adapting a Tabu Search algorithm in which the assembly process and the supply chain design are considered at the same time.     

Spatial variability of carbonaceous aerosol concentrations in East and West Jerusalem

Carbonaceous aerosol concentrations and sources were compared during a year long study at two sites in East and West Jerusalem that were separated by a distance of approximately 4 km. One in six day 24-h PM(2.5) elemental and organic carbon concentrations were measured, along with monthly average concentrations of particle-phase organic compound tracers for primary and secondary organic aerosol sources.Tracer compounds were used in a chemical mass balance ICMB) model to determine primary and secondary source contributions to organic carbon. The East Jerusalem sampling site at Al Quds University experienced higher concentrations of organic carbon (OC) and elemental carbon (EC) compared to the West Jerusalem site at Hebrew University. The annual average concentrations of OC and EC at the East Jerusalem site were 5.20 and 2.19 μg m(-3), respectively, and at the West Jerusalem site were 4.03 and 1.14 μg m(-3), respectively. Concentrations and trends of secondary organic aerosol and vegetative detritus were similar at both sites, but large differences were observed in the concentrations of organic aerosol from fossil fuel combustion and biomass burning, which was the cause of the large differences in OC and EC concentrations observed at the two sites.