Physical properties of disordered chalcogenide solar cell from Pb20Ge x Se80 − x thin films

The preparation and study of homogeneous p-n junctions from amorphous chalcogenide Pb₂₀Ge _x Se_{80 ? x} by thermal evaporation are presented. Such p-n junction is a novel module since no one had fabricated such homogeneous cell from these amorphous compounds yet. The p-type layer is Pb₂₀Ge₂₀Se₆₀ and the n-type is Pb₂₀Ge₂₅Se₅₅ elemental analysis of n- and p-types of Pb₂₀Ge _x Se_{80 ? x} is confirmed by energy dispersive X-ray analysis. Optical energy gaps were determined from transmission spectra in the range of 300 to 2500 nm; these values was 1.9 eV for p-Pb₂₀Ge₂₀Se₆₀ and 2.0 eV for n-Pb₂₀Ge₂₅Se₅₅ thin films. The J-V characteristics in the dark are exhibited rectification in the reverse voltage resulting from junction. The reverse current under illumination shows no saturation with voltage. From I-V characteristics under illumination and the spectral response the open circuit voltage V _oc and I _sc were measured. Capacitance measurements are the main method to evaluate doping concentration through the solar cell. The distribution of charged carriers across the depletion region was calculated and interpreted.     

Oxidation of Zirconium Diboride–Silicon Carbide at 1500°C at a Low Partial Pressure of Oxygen

The oxidation behavior of zirconium diboride containing 30 vol% silicon carbide particulates was investigated under reducing conditions. A gas mixture of CO and ∼350 ppm CO₂ was used to produce an oxygen partial pressure of ∼10⁻¹⁰ Pa at 1500°C. The kinetics of the growth of the reaction layer were examined for reaction times of up to 8 h. Microstructures and chemistries of reaction layers were characterized using scanning electron microscopy and X-ray diffraction analysis. The kinetic measurements, the microstructure analysis, and a thermodynamic model indicate that oxidation in CO–CO₂ produced a non-protective oxide surface scale.     

A learning automata and clustering-based routing protocol for named data networking

Named data networking (NDN) is a new information-centric networking architecture in which data or content is identified by a unique name and saved pieces of the content are used in the cache of routers. Certainly, routing is one of the major challenges in these networks. In NDN, to achieve the required data for users, interest messages containing the names of data are sent. Because the source and destination addresses are not included in this package, routers forward them using the names that carried in packages. This forward will continue until the interest package is served. In this paper, we propose a routing algorithm for NDN. The purpose of this protocol is to choose a path with the minimum cost in order to enhance the quality of internet services. This is done using learning automata with multi-level clustering and the cache is placed in each cluster head. Since the purpose of this paper is to provide a routing protocol and one of the main rules of routing protocol in NDN is that alternative paths should be found in each path request, so, we use multicast trees to observe this rule. One way of making multicast trees is by using algorithms of the Steiner tree construction in the graph. According to the proposed algorithm, the content requester and content owners are the Steiner tree root and terminal nodes, respectively. Dijkstra’s algorithm is one of the proper algorithms in routing which is used for automata convergence. The proposed algorithm has been simulated in NS2 environment and proved by mathematical rules. Experimental results show the excellence of the proposed method over the one of the most common routing protocols in terms of the throughput, control message overhead, packet delivery ratio and end-to-end delay.     

Adhesion promotion of thick polyphosphate-poly(allylamine) films onto polyolefin substrates by plasma polymers

The adhesion of thick poly(allylamine)-polyphosphate layers (1 μm) deposited by the wet-chemical layer-by-layer (LbL) technique onto polyethylene or polystyrene (each 100 μm) was very low. To promote the adhesion of these LbL deposited layers, the polyolefin substrates were oxidized at the surface by short exposure to the oxygen plasma (2 or 5 s) and subsequently coated with an interlayer of plasma-deposited poly(allylamine) or poly(allyl alcohol) (100 nm). The plasma polymer interlayers have improved strongly the adhesion between polyolefin substrates and polyphosphate coatings. Such phosphate coatings are interesting for life sciences (nucleotide formation) but also for fire retardancy in combination with N-rich compounds such as melamine. The intention was to prefer chemical hydrogen bonds for adhesion promoting because of their high binding energy. Therefore the introduced oxygen-containing groups at the polyolefin surface could interact with the OH or NH₂ groups of the adhesion-promoting plasma polymer interlayer. These groups were also able to interact strongly with the poly(allylamine)-polyphosphate topcoating. The coated polyolefins were investigated using Fourier transform infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR), X-ray photoelectron spectroscopy, thermogravimetric analyses and atomic force spectroscopy, and 90° peel test.     

Analysis of Anabaena vaginicola and Nostoc calcicola from Northern Iran,as rich sources of major carotenoids

Four major carotenoids of high nutritional significance, including β-carotene, lycopene, lutein and zeaxanthin were determined in three isolates of heterocystous cyanobacteria, belonging to the genera Anabaena and Nostoc, isolated from Iranian terrestrial and aquatic ecosystems, for the first time. The ultrasonically extracted carotenoids were identified and quantified by a rapid and sensitive isocratic HPLC method and identification was further confirmed by spiking authentic standards and the pattern of the UV–Vis spectra obtained from photo-diode array detector. The results showed that these isolates contain large amounts of four major carotenoids, especially lycopene (up to 24570 μg/g dry weight, DW) which appears to be the highest reported amount until present; and β-carotene (up to 8133 μg/g DW) which is comparable with the best natural sources of β-carotene. Meanwhile, they are rich in the cis-isomers of lycopene and β-carotene which is important in their bioavailability and health benefits.     

Performance evaluation of manufacturing systems based on dependability management indicators—case study: chemical industry

Dependability is a key decision factor in today’s global business environment affecting product cost and process. Dependability reflects user confidence in fitness for use by attaining satisfaction in product performance capability, delivery, service availability upon demand, and minimizing cost. The main objective of this study is to develop an integrated approach for evaluation of manufacturing systems based on dependability indicators for conducting a better dependability management system (DMS) through integration of the principal component analysis (PCA) and the data envelopment analysis (DEA). To achieve the objective of this study, an industrial sector—chemicals and chemical products in Iran—is selected as the case of this study in accordance with the International Standard for Industrial Classification of all economic activities (ISIC). Firstly, we define dependability indicators, for both inputs and outputs, based on IEC 60300. Due to the extra amount of indicators, we utilize a hierarchical structure to cluster the indicators for an easier analysis. Secondly, for reducing the number of some variables, we apply pair-wise comparison to assign weights and to unify the related sub-criteria to one main criterion. Finally, an integrated DEA–PCA approach is employed to assess the most and the least dependable units and to find critical indicators in macro and micro levels in order to make policy for implementation of DMS in manufacturing systems.     

Lipidomic and Proteomic Alterations Induced by Even and Odd Medium-Chain Fatty Acids on Fibroblasts of Long-Chain Fatty Acid Oxidation Disorders

Medium-chain fatty acids (mc-FAs) are currently applied in the treatment of long-chain fatty acid oxidation disorders (lc-FAOD) characterized by impaired β-oxidation. Here, we performed lipidomic and proteomic analysis in fibroblasts from patients with very long-chain acyl-CoA dehydrogenase (VLCADD) and long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHADD) deficiencies after incubation with heptanoate (C7) and octanoate (C8). Defects of β-oxidation induced striking proteomic alterations, whereas the effect of treatment with mc-FAs was minor. However, mc-FAs induced a remodeling of complex lipids. Especially C7 appeared to act protectively by restoring sphingolipid biosynthesis flux and improving the observed dysregulation of protein homeostasis in LCHADD under control conditions.     

Processing and impact behavior of Al/SiCp composites fabricated by the pressureless melt infiltration method

In the current investigation, pressureless melt infiltration was applied to fabricate the Al/SiC composites based on the SiC porous preforms. The process was conducted by introducing the aluminum melt into the SiC preforms at 950 °C under the nitrogen atmosphere, without the aid of pressure. To explore development of melt infiltration, initial preforms were produced with variable SiC fractions (40, 50, and 60 vol.%) using three different SiC powders with the mean particle size of 20, 50, and 90 μm. While the infiltration of aluminum melt into the preforms with 40 vol.% initial SiC volume fraction (SiC particle size of 90 μm) resulted to the composites with final density of 0.94 theoretical density (TD), this value drops down to ～0.9 TD for the composites produced by preforms with the SiC (90 μm) volume fraction of 60 vol.%. On the other hand, composites fabricated by 50 μm SiC powder (SiC volume fraction of 40 vol.%) demonstrated the final density of ～0.91 TD. The impact resistance tests performed on the composites demonstrated an enhancement in the value of impact energy with an increase of SiC powder particle size. Results, additionally, revealed a significant superiority of impact energy for the composites fabricated by a combined melt infiltration and sintering (MIS) procedure compared to those produced by infiltration at 950 and 1350 °C.     

Pectin extraction from citron peel: optimization by Box–Behnken response surface design

In this study, the effect of acidic extraction conditions (time of 30–90 min, temperature of 75–95 °C and pH of 1.5–3) on the yield and degree of esterification (DE) of citron peel pectin was investigated applying Box–Behnken design. The highest production yield of pectin (28.31?±?0.11%) was achieved at extraction time of 90 min, temperature of 95 °C and pH of 1.5, as optimal extraction conditions, which was close to the predicted value (29.87%). Under optimum extraction conditions, the DE and the emulsifying activity were 51.33 and 46.2%, respectively. In addition, the emulsions were 93.9 and 93.5 stable at 4 °C, 93.7 and 93.1 at 23 °C after 1 and 30 days, respectively. The determination of flow behavior showed that the pectin solutions had a Newtonian behavior at low concentrations (<?1.0% w/v), while this behavior was changed to pseudoplastic with increasing concentration.