Efficient conversion of light paraffinic naphtha to aromatics over metal-modified Mo/MFI catalysts

Journal of Porous Materials - The transformation of light naphtha to value-added aromatic compounds is gaining momentum in the petrochemical industry. In this work, a series of metal modified...     

Methods of analysis modified size exchange chromatography method for analysis of heavy oil residues

A modified size exchange chromatography method is used to obtain molecular weight distributions, average molecular weight, and other characteristics of heavy oil residues: coal asphalt, petroleum asphalt, vacuum residue oil, and ethylene residue oil. This method can be applied for developing and studying processes involved in hydrogenation of heavy oil residues, road asphalt production, and coal liquefaction.     

Wireless networking in tunnelling projects

Emerging collaborative technologies and working methods often require tremendous engineering and organisational efforts for successful implementation of information and communication technologies (ICTs). According to a research conducted in Turkish construction industry, most of the problems that occur during the construction phase are due to lack of co-operation and communication between designers and contractors and lack of prompt expert decisions during on-site engineering. Similar to any major construction project, tunnelling project’s success is highly dependent on collaborative team work where communication and information exchange take place between project members. Distributed collaborative teamwork, as the case in most of the large scale construction projects as well as tunnelling projects, empowered by state of the art information and communication technology, promises more efficient work processes, reduced travelling needs, and increased opportunities for project communication. Following the fast development of mobile computing in recent years, many sectors have adopted mobile devices and wireless technologies enabling real-time information transfer thereby improving business processes. For some years, the feasibility of implementing wireless solutions to construction sites has been researched. Potentially, mobile and wireless technologies enable construction staff to be more flexible in terms of location and time. For better use of mobile collaboration in construction projects, mobile technologies and construction sector have to be examined in some detail to implant the most suitable technology for real-time information access and improved collaboration of distributed teams in construction. However, case studies in construction are very limited in number and scope. This paper discusses and proposes an implementation scenario of wireless networking in Marmaray; a multi-site tunnelling project in Istanbul. Benefits, possible problems and cost assessments are discussed.     

The Effect of Olive Leaf Addition on Antioxidant Content and Antioxidant Activity of “Memecik” Olive Oils at Two Maturity Stages

In this study, the effects of leaf addition, maturity stage and storage on the antioxidant content and activity of olive oils (cv. Memecik) were investigated in the 2008/09 and 2009/10 crop seasons. Olive fruits were harvested at two different maturity stages (early and late), and the leaves of the same cultivar were added at different rates (0, 1, and 3 %) prior to oil extraction. After extraction, the oil samples were stored for 18 months and total chlorophyll, α-tocopherol, total phenolic content and the antioxidant activity [DPPH^· (2,2-diphenyl-1-picrylhydrazyl) and ABTS^·+ (2,2-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid) radical scavenging] were determined at 6 month-intervals. Olive leaf addition induced a significant increase in total chlorophyll, α-tocopherol, total phenolic content, and antioxidant activities in both years (P < 0.001). During the storage period antioxidant content and antioxidant activities in the oils significantly decreased in both years (P < 0.001). However, the oils to which leaf material was added had higher antioxidant contents and activities than those without leaf material addition at the end of the 18-month storage period. After storage, the antioxidant content and DPPH^· radical scavenging activity of control (0 %) samples were lower than those in the leaf added samples (3 %). The data obtained from this study suggested that the addition of olive leaf to oils allowed more functional olive oils with higher antioxidant contents.     

Crisis Readiness in Turkey and the United States

Crisis management seeks to minimize the impact that crisis events have on organizations. While the crisis management literature is replete with studies of large organizations in developed countries, little has been written on this subject concerning businesses in emerging nations. This exploratory study investigates the perceptions and experiences of Turkish managers in relation to crisis events. Crisis readiness in Turkey and the United States is compared and contrasted. The results indicate that a majority of these organizations do not have formal crisis management plans. Recommendations are offered and implications for management are presented.     

Selective extraction of phosphatidylcholine from lecithin by supercritical carbon dioxide/ethanol mixture

Selective extraction of phosphatidylcholine (PC) from deoiled soybean lecithin using supercritical fluid (SCF) mixtures of carbon dioxide (CO₂) and ethanol was studied at moderate pressures. Temperature was varied between 60 and 80°C at pressures of 17.2 and 20.7 MPa. Ethanol was added as co-solvent to supercritical CO₂ at the levels of 10 and 12.5 wt%. Constant rate of extraction of the individual phospholipids (PL) was observed for 150 min during which the extractions were carried out. Pressure and ethanol fraction had a positive effect on the selective extraction of PC, whereas temperature had a negative effect. Under all the conditions studied, the extracts were mainly composed of PC while the extraction of the other PL was very low. Extraction at 60°C and 20.7 MPa with 10 wt% ethanol/90 wt% CO₂ SCF mixture resulted in 95% selectivity to PC.     

The effect of flow field and turbulence on heat transfer characteristics of confined circular and elliptic impinging jets

The flow field of confined circular and elliptic jets was studied experimentally with a Laser Doppler Anemometry (LDA) system. In addition, heat transfer characteristics were numerically investigated. Experiments were conducted with a circular jet and an elliptic jet of aspect ratio four, jet to target spacings of 2 and 6 jet diameters, and Reynolds number 10 000. The toroidal recirculation pattern was observed in the outflow region for both geometries at dimensionless jet to plate distance 2. Higher spreading rates in the minor axis direction of the elliptic jet have also been mapped. Along the target plate, different boundary layer profiles were obtained for circular and elliptic jets at H/d=2, but profiles became similar when dimensionless jet to plate distance was increased to 6. Positions of maximum radial and axial velocities and turbulence intensities have been determined for both geometries. For the confined circular and elliptic jet geometries, analysis of flow field measurements and numerical heat transfer results showed that inner peaks in local heat transfer closely relate to turbulence intensities in the jet and radial flow acceleration along the wall. Differences between the circular and elliptic jet, in terms of flow field and heat transfer characteristics, reduced with increase in the jet to plate distance.     

Effects of expander process on the phospholipids in soybean oil

Crude oils were extracted from soybean flakes and collets by conventional and expander processes, respectively. The phospholipids were removed by degumming, and the lecithins were produced by using commercial procedures. The effects of the expander process on the degumming efficiencies were evaluated. The differences in the phosphatide compositions of the oils and the lecithins produced from expander and conventional processes were compared by high-performance liquid chromatography. The phosphorus content indicated that expander-processed oil contained more phosphorus (985 ppm) than the conventional oil (840 ppm). However, the phospholipids in the expander-processed oil were more hydratable than those in the conventional oil. After degumming, the phosphorus content in the expander-processed and conventional oil were reduced by 93.2 and 78.6%, respectively. The expander-processed lecithin contained 74.3% acetone-insoluble matter (AI), and the conventional lecithin contained 65.8%. More phosphatidylcholine was found in the expander-processed lecithin (39.78%, based on AI) than in the conventionally processed lecithin (34.19%). The phosphatidylinositol contents of the expander-processed lecithin and the conventional lecithin are almost the same (19.95 and 19.97%). The phosphatidylethanolamine in the expander-processed lecithin (12.36%) was lower than that in the conventional lecithin (18.07%).     

The Fabrication of THz Emitting Mesas by Reactive Ion-Beam Etching of Superconducting Bi2212 with Multilayer Masks

Generation of powerful THz radiation from intrinsic Josephson Junctions (IJJs) of Bi₂Sr₂CaCu₂O_8+?? (Bi2212) may require mesas with large lateral dimensions. However, there are difficulties in fabrication of perfect rectangular mesas. The lateral angles of mesas should be close to 90 degrees to obtain IJJs with same planar dimensions for synchronization of IJJs. We patterned Ta/photoresist and photoresist/Ta/photoresist masks on Bi2212 and used selective ion etching to overcome the thick photoresist layer shading on the lateral dimension of mesa during the ion-beam etching. The reactive ion-beam etchings have been done with ion beams of Ar, N₂ and O₂, and we have obtained mesas about 1 ??m with lateral angle of approximately 50 to 75°, which is better than the mesas fabricated with photoresist mask.     

Influences of Pb Substitution on Microstructure,Electrical Transport,and Mechanical Properties of Single-Crystal FeTe0.5Se0.5 Superconductors

Journal of Superconductivity and Novel Magnetism - In this work, single crystals of superconducting Fe1-xPbxTe0.5Se0.5 (x?=?0.0, 0.01, 0.05, and 0.1) were grown by self-flux method. The...