196,251 research outputs found
Multi-response analysis in the processing of poly (methyl methacrylate) nano-fibres membrane by electrospinning based on response surface methodology: fibre diameter and bead formation
No full textAbstract not availableH.M. Khanlou, B.C. Ang, S. Talebian, M.M. Barzani, M. Silakhori and H. Fauz
Pitting corrosion inhibition of 304 stainless steel in NaCl solution by three newly synthesized carboxylic Schiff bases
No full textThree newly synthesized Schiff base derivatives, sodium (E)-4-(nitrobenzylideneamino)-benzoate (SNBB), sodium (E)-4-(benzylideneamino)-benzoate (SBB), and sodium (E)-4-(hydroxybenzylideneamino)-benzoate (SHBB) were investigated as pitting corrosion inhibitors for 304 stainless steel in neutral 0.1 M NaCl. Potentiodynamic polarization evidenced major shifts in pitting potential to more positive values with increasing inhibitor concentration. The scanning vibrating electrode technique (SVET) imaged metastable pitting in 0.1 M NaCl, but not in the presence of the inhibitor, indicating that it prevented pit nucleation. The inhibition performance was established under anodic polarization conditions, because only minute local anodic activity due to metastable pit formation could be observed when the steel was exposed to SNBB-containing solution, whereas the metal would undergo pit propagation at the same potential in the inhibitor-free solution. X-ray photoelectron spectroscopy (XPS) analysis evidenced chromium enrichment at weak points (pores) of the passive film at anodic polarization condition where sudden release of Fe cations is possible. In this way, the SNBB molecules will migrate to these sites to react with the Fe ions and form a chelate compound which will deposit finally at those sites and plug them, whereas no effect occurred at the open circuit potential (OCP)
Computational Modeling of Hydro-Electro-Mechanical Flow During CO2 Geosequestration
No full textCO2 geo-sequestration (CGS) is considered to be a feasible technology for reducing the amount of CO2 emission into the atmosphere. Selection of an appropriate reservoir is vital and requires appropriate knowledge of the involved phenomena and processes. In a CO2 geo-sequestration process, carbon dioxide goes through mainly four storage (trapping) mechanisms: structural and stratigraphic trapping, residual trapping, solubility trapping and mineral trapping. In this study, focus is placed on modeling the first trapping mechanism, together with corresponding deformation and electrokinetic flow. Multiphase fluid flow due to injection of CO2 in an unsaturated reservoir is accompanied by continuous redistribution of pore pressure and effective stress, causing local and regional deformations and probably major uplifting or subsidence. This flow is also accompanied by electrokinetic flow. In such a system, electrokinetic potentials occur due to the interaction between the formation fluid and the mineral grains. Due to pressure gradients, the flow of the pore fluid produces an advective electric current: such a flow generates an electric field, which produces a counter electric current through the interface, known as the self-potential (SP). Since the electrical conductivity of CO2 is lower than that of the formation brine, it can be detected by measuring the self-potential. Based on this, the SP can be used for monitoring CO2 plume movement, a necessary procedure to ensure that geologic sequestration is both safe and effective. In spite of the versatility of the available numerical tools, attempts to model CO2 geo-sequestration in a region and considering events occurring in local areas lead to enormous demands for computational power. This makes the development of numerical tools for CO2 geo-sequestration not only difficult, but rather expensive. In this study, the governing field equations are derived based on the averaging theory and solved numerically based on a mixed discretization scheme. In this scheme, variables exhibiting different nature are treated using different numerical discretization techniques. Techniques such as the standard Galerkin finite element method (SG), the extended finite element method (XFEM), the level-set method (LS) and the Petrov-Galerkin method (PG) are integrated in a single numerical scheme. SG is utilized to discretize the deformation and the diffusive dominant field equations, and XFEM, together with LS, are utilized to discretize the advective dominant field equations. The level-set method is employed to trace and locate the CO2 plume front, and the XFEM is employed to model the associated high gradient in the saturation field front. The use of XFEM for the advective field leads to a computationally efficient, stable and effectively mesh-independent discretization. However, it gives rise to an extra degree of freedom. The use of SG for the deformation and the diffusive fields requires only standard degrees of freedom, limiting the total number of degrees of freedom and making the scheme computationally efficient. Several verification and numerical examples are presented for both homogenous and fractured reservoirs. The examples demonstrate the capability of the proposed mixed discretization model to simulate challenging, coupled analyses. It has been shown that this model is capable of solving problems, which typically involve several state variables with different transient nature, using relatively coarse meshes.Structural EngineeringCivil Engineering and Geoscience
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
(M=Cd, Ni, and Mn) Janus Atomic Junctions for Plasmonic Energy Upconversion Boosted Multi‐Functional Photocatalysis
No full textRational design/synthesis of atomic-level-engineered Janus junctions for sunlight-impelled high-performance photocatalytic generation of clean fuels (e.g., H2O2 and H2) and valuable chemicals are of great significance. Especially, it is appealing but challenging to acquire accurately-engineered Janus atomic junctions (JAJs) for simultaneously realizing the plasmonic energy upconversion with near-infrared (NIR) light and direct Z-scheme charge transfer with visible light. Here, a range of new Cu7S4/MxSy (M=Cd, Ni, and Mn) JAJs are designed/synthesized via a cation-exchange route using Cu7S4 hexagonal nanodisks as templates. All Cu7S4/MxSy JAJs show apparently-enhanced photocatalytic H2O2 evolution compared to Cu7S4 in pure water. Notably, optimized Cu7S4/CdS (CCS) JAJ exhibits the outstanding H2O2 evolution rate (2.93 mmol g−1 h−1) in benzyl alcohol aqueous solution, due to the following factors: i) NIR light-impelled plasmonic energy upconversion induced H2O2 evolution, revealed by ultrafast transient absorption spectroscopy; ii) visible-light-driven direct Z-scheme charge migration, confirmed by in situ X-ray photoelectron spectroscopy. Besides, three different reaction pathways for H2O2 evolution are disclosed by in situ electron spin resonance spectroscopy and quenching experiments. Finally, CCS JAJ also exhibits super-high rates on H2 and benzaldehyde co-generation using visible-NIR light or NIR light. This work highlights the significance of atomic-scale interface engineering for solar-to-chemical conversion.Meijun Guo, Amin Talebian-Kiakalaieh, Bingquan Xia, Yiyang Hu, Hongjun Chen, Jingrun Ran, and Shi-Zhang Qia
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
Inhibitive effect of sodium (E)-4-(4-nitrobenzylideneamino)benzoate on the corrosion of some metals in sodium chloride solution
No full textThe inhibition performance of a novel anionic carboxylic Schiff base, sodium (E)-4-(4-nitrobenzylideneamino)benzoate (SNBB), was investigated for various metals, namely low carbon steel F111, pure iron and copper, in neutral 10 mM NaCl solution. Potentiodynamic polarization, scanning vibrating electrode technique (SVET), quantum chemical (QC) calculation, and molecular dynamics (MD) simulation were employed. The potentiodynamic polarization data showed that SNBB acts as an effective corrosion inhibitor for both iron and F111 steel, but it is not effective for copper. In situ spatially-resolved SVET maps evidenced a major change in surface reactivity for Fe and F111 steel immersed in 10 mM aqueous solution in the absence and in the presence of SNBB. Featureless ionic current density distributions were recorded in the presence of SNBB at both their spontaneous open circuit potential (OCP) and under mild anodic polarization conditions, while major ionic flows were monitored above the metals in the absence of SNBB. On the basis of computer simulations, it is proposed that SNBB produces a stable chelate film on iron and steel surfaces that accounts for the good corrosion inhibition efficiency observed. The different inhibition efficiencies of SNBB molecules on iron and copper was attributed to the special chemical structure of the SNBB molecule, and its different chelation ability with the released metal ions on the metal surface. The QC calculations also confirmed the high corrosion inhibition efficiency of SNBB. The MD simulation indicated higher binding energy of SNBB on iron surface compared to that of copper surface. The interaction mode of SNBB on iron and F111 steel surfaces corresponds to a mixed chemical and physical adsorption, and it obeys the Langmuir isotherm
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