Abstract: Modifying polyoxometalates with organic and/or metal-organic moieties is a widely adopted method for broading the range of properties. In this work a new polyoxometalate constructed from Anderson-type polyoxoanions and L-arginine (Arg = L-arginine) molecules Na [CrMo6(OH)6O18]}(H2Arg)2·8H2O(1) has been synthesized via conventional method and characterized by routine techniques. Single-crystal X-Ray diffraction analysis shows that compound 1 is constructed by chiral L-arginine grafted Anderson-type clusters, sodium cation and water molecules which are further stabilized by hydrogen bonding interactions constitute 3D supramolecular networks. In addition, both antitumor behavior and photocatalytic activities of compound 1 were investigated.
Abstract: The ambition of the world oil industry is currently directed toward the deepest traps of oil and gas, despite the very high temperatures. The objective of this study is to improve and control a conventional formulation of cement slurry that meets the critical conditions during the cementing of 7" liner on high pressure/high temperature (HPHT) gas well at 5570m depth, located at Hassi Berkine in the southern Algeria. Under the influence of high temperature, the characteristics of the cement slurry changed. We carried out several tests on various samples in order to revise the design by using equivalent substitutions of the additives to obtain a better profile. The use of a new, very powerful, synthetic retarder (SR-31L) instead of liquid, modified sodium lignosulfonate (R-15 L) led us to obtain a significant thickening time but decreased the rheological properties as well as fluid loss and free water. We also provided a gas block by introducing latex-styrene-butadiene with a specific stabilizer (LS-1) in combination with a compatible bonding agent (amorphous silica) in aqueous suspension (BA-58L). The study determined one of the best cement slurry designs practicable on different down-hole applications in HPHT wells.
Abstract: This study deals with the paramount topic of sustainable and durable composite materials for repair of damaged existing bridge. Reinforced concrete is the most used composite system in structural design but, across several decades, it has shown some fragilities related to chemico-physical resistance. Durability improvement by means of innovative repair systems represent, therefore, a crucial economic parameter allowing a highly significant reduction of maintenance cost. A maintenance scenario is here simulated, considering a repair composite realized with a binary geopolymer binder, obtained by activating two industrial by-products, namely coal fly ash and blast furnace slag, in alkaline environment. Physico-mechanical characterization of geopolymer concrete is also performed, showing the suitability of this innovative repair system. In order to investigate the effectiveness of geopolymer, a 3D finite element model is developed in Sap2000 to represent the complex behavior of a full-scale Italian highway bridge. Numerical simulations are conducted by modeling the geopolymer concrete as a jacketing applied to the damaged piers. Results reveal that the designed repair system could increase shear capacity of bridge piers under seismic conditions, not neglecting the low cost of raw materials and the high durability of geopolymers.
Abstract: The reinforced clear coat on glass substrate was prepared by coating waterborne-polyurethane hybridized by silica sol or aluminate modified silica sol. To enhance the physicochemical property of the film, aluminate modified silica particle was prepared by the interaction between sodium aluminate and cation-exchanged silica. The hybrid thin films were developed in the range of the modified silica content varying from 0 to 20 wt%. The film, containing the modified silica content of 16 wt%, exhibits markedly improved properties as compared to the neat polyurethane and the polyurethane containing silica particle; e.g., an improved hardness, chemical and abrasion resistance, with maintaining the transparence. However, the film transparence was decreased with modified silica content above 18 wt%, and its hardness was not improved with its content below 14 wt%.
Abstract: The geosynthetic materials are extensively used in a wide range of applications in civil engineering. In this study, a nonwoven high strength geotextile which is generally utilized as a reinforcing material for earth structures and a ultrahigh molecular weight polyethylene (UHMWPE) geomembrane (generally used to seal the inner face of toxic liquid tanks against leakage) are used together beneath structures for seismic isolation purposes. The dynamic interface properties of the surface formed between these two materials have been tested on small scale models by shaking table tests. The results were impressive such that the accelerations transferred to the superstructure were significantly reduced. Also, it was observed that the materials used during the research had almost no abrasion at the end of a series of experiments which revealed that the tested materials could be used for repetitive dynamic loadings.
Abstract: Graphene because of its higher surface area, strength, thinness and high electric conductivity has diversified uses from mechanical, electrical to bio medical engineering. This paper presents an initial study on modifying 80/100 penetration grade bitumen with Graphite oxide (GO) prepared by using Simplified Room Temperature Hummer’s process. The concept of utilizing GO for modification is adopted in order to improve the stiffness of the binder which can be helpful in reducing rutting potential of the pavement and to have electro thermal conductivity in modified binder, thus can be used during pavement remediation work. The limited trial rheological results obtained for 0.1125 wt. % GO modified bitumen and 0.225 wt. % GO modified bitumen showed that modification of bitumen with GO has improved its elastic capacity at higher temperature and lower frequency regime thus successfully can be used as bitumen modifier in future.
Abstract: The present work concerns the geometrically non-linear free vibration of fully clamped functionally graded skew plates (FGSP). The theoretical model based on Hamilton’s principle and spectral analysis is used. A homogenization technique has been developed to reduce the FGSP problem under consideration to that of an isotropic homogeneous skew plate. The material properties of the skew plate examined herein are assumed to be graded in the thickness direction of the plate according to the power-law distribution in terms of volume fractions of the constituents. Results are given for the linear and non-linear fundamental frequency considering different parameters. The non-linear mode shapes exhibit a maximum value in the bending stress at the centre of the plate. It is found also that the non-linear frequencies increase with increasing the amplitude of vibration and increasing the skew angle, which corresponds to the hardening type effect. A good agreement is found with published results.
Abstract: Several analytical, numerical and experimental techniques are available to study the stress concentration around the notches. The stress distribution in a rectangular composite laminated plate with a central notch was studied using the finite element method. The objective of this study is to analyze the fibre orientation effect on the variation of stress concentrations at the notch root and the J-integral at the crack-tip emanating from this notch in a plate subjected to tensile loading. The results show that the anisotropic stress concentration factor can be higher or lower than that of a homogeneous material. The area of maximum normal and tangential stresses could shift with fibre orientation with respect to the loading axis. The interaction effect between a crack located on the ligament of the plate and the circular notch of radius is considered.The results indicate that fold sequence influences appreciably the acceleration or the retardation of the crack propagation.
Abstract: Durable, renewable, and affordable are the three characteristics of the adobe brick, one of the widely used construction material in human civilization, but is always neglected. Traditionally, price has been the foremost consideration when comparing similar materials or materials designated for the same function. That is why by the post-war period, the concrete was adopted as a universal building material in response of the massive housing demand. The intergovernmental concerns never took into consideration both the sustainability factor and the cultural one, not until the 1990s when research on climate change expanded and the sustainable development took an important place in the different academic cross fields: engineering, biology, technology and architecture. The main focus by then was the reduction the CO2 gas emissions emitted by the building sector which is now approximately 30% of the global energy-related. Researchers are focusing on creating a completely new green eco-material an alternative to the concrete, but in this paper, I will demonstrate why is it worth to reinvigorate centuries-old eco-construction material. Adobe bricks are currently the best choice to built affordable housings in response to the chronicle demand. Not only they have a track record that makes their thermal mass performance easier to evaluate, but also they can last 400 years or more when properly maintained. Comparatively, new technologies require testing over time to determine their long-range effectiveness.
Abstract: In this paper the SEE (single event effects) of different parts of device were explored on a 32-bit microprocessor with a five-stage instruction pipeline by laser test and heavy ion test. The cross section curves for different function units were obtained and the comparison of the dates obtained from laser test and heavy ion tests was made. In addition, laser test under different scanning steps were made which indicate that when the scanning step length is in small steps which is considerably equivalent to the laser spot size, there is little change in the number of single event errors caused by each laser pulse. Wherever with the scanning step increasing, the number of single event errors caused by each laser pulse will be reduced. Experiment results suggest that there are differences between laser test and the heavy ion test but have a similar trend. The pulsed laser is an extremely powerful and low-cost technique for SEE testing and will provide invaluable information in characterizing SEE in integrate circuits.