Effects of Ta Content on Thermodynamic Properties and Transformation Temperatures of Shape Memory NiTi Alloy

Metals and Materials International - In the present work, Ni32-x-Ti-Ta18+x (x?=?0, 2, 3, 4, 5, 6, 7, 8) shape memory alloys, produced by arc-melting method. Then, differential scanning...     

Pharmacological Mechanisms Underlying Gastroprotective Activities of the Fractions Obtained from Polygonum minus in Sprague Dawley Rats

The leaves of Polygonum minus were fractionated using an eluting solvent to evaluate the pharmacological mechanisms underlying the anti-ulcerogenic activity of P. minus. Different P. minus fractions were obtained and evaluated for their ulcer preventing capabilities using the ethanol induction method. In this study, Sprague Dawley rats weighing 150-200 g were used. Different parameters were estimated to identify the active fraction underlying the mechanism of the gastroprotective action of P. minus: the gastric mucus barrier, as well as superoxide dismutase, total hexosamine, and prostaglandin synthesis. Amongst the five fractions from the ethanolic extract of P. minus, the ethyl acetate:methanol 1:1 v/v fraction (F2) significantly (p < 0.005) exhibited better inhibition of ulcer lesions in a dose-dependent manner. In addition, rats pre-treated with F2 showed a significant elevation in superoxide dismutase (SOD), hexosamine and PGE2 levels in the stomach wall mucosa in a dose-dependent matter. Based on these results, the ethyl acetate:methanol 1:1 v/v fraction was considered to be the best fraction for mucous protection in the ethanol induction model. The mechanisms underlying this protection were attributed to the synthesis of antioxidants and PGE2.     

Synthesis and characterization of nanostructured SnO<Subscript>2</Subscript> film

Nanostructured tin dioxide (SnO₂) film was deposited on glass substrate by thermal evaporation of tin metal followed by thermal oxidation at 600 °C for 2 h. XRD investigation confirms that grown film is crystalline tetragonal rutile. The average optical transmittance of the film was as high as 90%. The optical band gap of the nanostructured SnO₂ was estimated from transmittance data and found to be 3.4 eV. The variation of electrical conductivity with temperature was investigated. The root mean square (RMS) roughness and topography of the film were investigated by atomic force microscopy and found to be 2 nm with grain size of 17 nm.     

Stochastic prediction of voltage sags in a large transmissionsystem

This paper discusses two stochastic prediction methods for voltage sags and applies them to a 97-bus model of the 400 kV National Grid of England and Wales. The method of fault positions is most suitable for implementation in a software tool. It has been used to get exposed areas and sag frequencies for each bus. The results are presented in different ways, including a so-called voltage sag map showing the variation of the sag frequency through the network. The method of critical distances is more suitable for hand calculations, as both the amount of data and the complexity of the calculations are very limited. It has been used to obtain sag frequencies for a number of buses. A comparison with the results obtained by using the method of fault positions shows that the method of critical distances is an acceptable alternative where software or system data are not available for a more accurate analysis     

Thermal behavior and shape memory properties of PCL blends film with PVC and PMMA polymers

Iranian Polymer Journal - Shape memory polymers have attracted extensive attention attributable to their characteristics and abundant applications. In this study, shape memory behavior and...     

Optimal location of advanced static VAR compensator (ASVC) applied to non-linear load model

The advanced static VAR compensator (ASVC) device is now recognized as one of the most important Flexible Alternating Current Transmission Systems (FACTS) devices. It has been proven that the mid-point of a transmission line is the optimal location for some FACTS devices or reactive power support, and the proof is based on the linear load, which is not valid practically. The validity of the optimal location of Pulse Width Modulation (PWM) based ASVC device is investigated when the non-linear load model is considered. In this paper, the ASVC applied to a non-linear load is modeled and analyzed. It was found that the optimum installation position for this device is at the sending end bus, where the wide range of receiver terminal line voltage and active power can be controlled. It was found that a wider range of reactive power could be controlled when the device is installed close to the receiving end bus.     

Calculation of Lattice Thermal Conductivity for Si Fishbone Nanowire Using Modified Callaway Model

Semiconductors - Semiconductor nanowires have low lattice thermal conductivity compared to the bulk materials, which is significant for developing thermoelectric. Lattice thermal conductivity of Si...     

ORGANIC AND INORGANIC GEOCHEMICAL AND MINERALOGICAL ASSESSMENTS OF THE SILURIAN AKKAS FORMATION,WESTERN IRAQ

The Silurian Akkas Formation has been reported and described only in the subsurface of western Iraq. The formation is divided into the lower Hoseiba Member, which contains two high‐TOC “hot” shale intervals that together are around 60 m thick, and the overlying Qaim Member that is composed of lower‐TOC “cold” shales. This study investigates the source rock potential of Akkas Formation shales from the Akkas‐1and Akkas‐3 wells in western Iraq and assesses the relationship between their mineral and elemental contents and their redox depositional conditions and thermal maturity. Twenty‐six shale samples from both members of the Akkas Formation from the Akkas‐1and Akkas‐3 wells were analysed. The results showed that the upper, ~20 m thick“hot” shale interval in the lower Hoseiba Member has good source rock characteristics with an average TOC content of 5.5 wt% and a mean Rock‐Eval S₂ of 10 kg/tonne. Taken together, the two “hot” shale intervals and the intervening “cold” shale of the Hoseiba Member are ~125‐150 m thick and have an average TOC of 3.3 wt% and mean S₂ of 6.2 kg/tonne. The samples from the Hoseiba Member contain mixed Type II / III or Type III kerogen with an HI of up to 296 mgS₂/gTOC. Visual organic‐matter analysis showed that the samples contain dark brown, opaque amorphous organic matter with minor amounts of vitrinite‐like and algal (Tasmanites) material. Pyrolysis – gas chromatography undertaken on a single sample indicated a mature (or higher) algal‐dominated Type II kerogen. High spore and acritarch colour index values and weak or absent fluorescence similarly suggest that the lower part of the Akkas Formation is late mature to early post‐mature for oil generation. “Cold” shales from the Qaim Member in the Akkas‐3 well may locally have good source rock potential, while samples from the upper part of the Qaim Member from the Akkas‐1 well have little source rock potential. Varied results from this interval may reflect source rock heterogeneity and limited sample coverage. Mineralogically, all the shale samples studied were dominated by clay minerals – illite and kaolinite with minor amounts of chlorite and illite mixed layers. Non‐clay minerals included quartz, carbonates, feldspars and pyrite along with rare apatite and anatase. Palaeoredox proxies confirmed the general link between anoxia and “hot” shale deposition; however, there was no clear relationship between TOC and U suggesting that another carrier of U could be present. Rare Earth Element (REE) contents suggested a slight change in sediment provenance during the deposition of the Akkas Formation. The presence of common micropores and fractures identified under SEM indicates that these shales could become potential unconventional reservoirs following hydraulic fracturing. Evidence for the dissolution of carbonate minerals was present along fractures, suggesting the possible passage of diagenetic fluids. Palynological analysis combined with existing graptolite studies support a Wenlock ‐ Pridoli/Ludlow age for the Akkas “hot”shales. This is younger than many other regional “hot shale” age estimates and warrants further detailed investigation.