The effect of undrained heating on a fluid-saturated hardened cement paste

The effect of undrained heating on volume change and induced pore pressure increase is an important point to properly understand the behaviour and evaluate the integrity of an oil well cement sheath submitted to rapid temperature changes. This thermal pressurization of the pore fluid is due to the discrepancy between the thermal expansion coefficients of the pore fluid and of the solid matrix. The equations governing the undrained thermo-hydro-mechanical response of a porous material are presented and the effect of undrained heating is studied experimentally for a saturated hardened cement paste. The measured value of the thermal pressurization coefficient is equal to 0.6 MPa/°C. The drained and undrained thermal expansion coefficients of the hardened cement paste are also measured in the heating tests. The anomalous thermal behaviour of cement paste pore fluid is back analysed from the results of the undrained heating test.     

Comparison of pressure driven transport of ethanol/n-hexane mixtures through dense and microporous membranes

The solvent flux was measured in binary mixtures of ethanol and n-hexane for nine solvent-stable polymeric membranes in range of reverse osmosis (RO) to ultrafiltration (UF) (GE AK Osmonics, Dow 102326, GE DK Osmonics, MPF-34, STARMEM™ 122, STARMEM™ 240, NF30, NTR7450, NF-PES-010). GC-analyses of feed and permeate samples showed a separation factor close to 1, which indicates the solvent transport occurs by convection or by coupled diffusion through the membranes. The effect of viscosity, surface tension, di-electric constant and solubility parameter of solvent on permeation rate was studied for four categories of membranes, i.e. RO membranes, dense nanofiltration (NF) membranes, semi-porous NF membranes and micro-porous NF membranes. While viscosity seems to be a main transport parameter (similar composition of feed and permeate), higher fluxes of ethanol compared to n-hexane (with lower viscosity) confirmed that the transport may occur through coupled diffusion. The influences of the solvent-membrane interaction parameters such as surface tension, polarity and solubility parameters of solvent and membranes for dense membranes were investigated. The effect of solvent membrane interaction by means of solubility parameters was more pronounced compared to surface tension since the respective surface tensions of solvents are close to one another . Partial permeabilities were studied as well to evaluate the influence of each component on permeation of the other. Unexpected results were observed for MPF-34, NF30 and NTR7450. Further investigation confirmed that their polymeric structure changed in contact with the solvents. Hydrophobic STARMEM™ membranes, which are expected to have a higher permeability for apolar solvents showed higher fluxes for ethanol compared to n-hexane. The similar solubility parameter of these membranes and ethanol may increase the permeation rate of ethanol molecules through membranes. For porous membranes viscosity was recognized as the key transport parameter, while affinity between membrane and solvent has a lower effect.     

A scalable LDPC decoder ASIC architecture with bit-serial message exchange

We present a scalable bit-serial architecture for ASIC realizations of low-density parity check (LDPC) decoders. Supporting the architecture's potential, we describe a decoder implementation for a (256,128) regular-(3,6) LDPC code that has a decoded information throughput of 250 Mbps, a core area of 6.96 mm² in 180-nm 6-metal CMOS, and an energy efficiency of 7.56 nJ per uncoded bit at low signal-to-noise ratios. The decoder is fully block-parallel, with all bits of each 256-bit codeword being processed by 256 variable nodes and 128 parity check nodes that together form an 8-stage iteration pipeline. Extrinsic messages are exchanged bit-serially between the variable and parity check nodes to significantly reduce the interleaver wiring. Parity check node processing is also bit-serial. The silicon implementation performs 32 iterations of the min-sum decoding algorithm on two staggered codewords in the same pipeline. The results of a supplementary layout study show that the reduced wiring congestion makes the decoder readily scaleable up to the longer kilobit-size LDPC codewords that appear in important emerging communication standards.     

Hybrid classifier for fault location in active distribution networks

This paper presents a fast hybrid fault location method for active distribution networks with distributed generation (DG) and microgrids. The method uses the voltage and current data from the measurement points at the main substation, and the connection points of DG and microgrids. The data is used in a single feedforward artificial neural network (ANN) to estimate the distances to fault from all the measuring points. A k-nearest neighbors (KNN) classifier then interprets the ANN outputs and estimates a single fault location. Simulation results validate the accuracy of the fault location method under different fault conditions including fault types, fault points, and fault resistances. The performance is also validated for non-synchronized measurements and measurement errors.     

Characterization of polystyrene latexes

Polystyrene latexes were prepared by emulsion polymerization. Styrene was used as monomer, potassium persulfate was the reaction initiator and sodium hydrogen carbonate was used as buffer. Surfactant may or may not be used. Three types of surfactant, ie sodium dodecylbenzene sulfonate (anionic), Triton X‐100 and Vulcastab LW (nonionic), and hexadecyltrimethyl ammonium bromide (cationic), were used. The prepared latexes were characterized according to concentration, density, pH, ionic strength, particle size, particle size distribution and surface charge. For prepared latexes with anionic surfactant, the effects of temperature, initiator concentration, surfactant concentration and amount of monomer on the latex size were investigated. Scanning electron microscopy was used as a tool for latex characterization. The results show that by increasing temperature, initiator and emulsifier concentration, the latex diameter decreases. However, size increases by increasing the amount of monomer. A potentiometric titration technique was employed for determination of surface charge. It was found that for all latexes, surface charge densities are in the same range. © 2000 Society of Chemical Industry     

Potential Effects of Sweet Potato (Ipomoea batatas) in Hyperglycemia and Dyslipidemia—A Systematic Review in Diabetic Retinopathy Context

Hyperglycemia is a condition with high glucose levels that may result in dyslipidemia. In severe cases, this alteration may lead to diabetic retinopathy. Numerous drugs have been approved by officials to treat these conditions, but usage of any synthetic drugs in the long term will result in unavoidable side effects such as kidney failure. Therefore, more emphasis is being placed on natural ingredients due to their bioavailability and absence of side effects. In regards to this claim, promising results have been witnessed in the usage of Ipomoea batatas (I. batatas) in treating the hyperglycemic and dyslipidemic condition. Thus, the aim of this paper is to conduct an overview of the reported effects of I. batatas focusing on in vitro and in vivo trials in reducing high glucose levels and regulating the dyslipidemic condition. A comprehensive literature search was performed using Scopus, Web of Science, Springer Nature, and PubMed databases to identify the potential articles on particular topics. The search query was accomplished based on the Boolean operators involving keywords such as (1) Beneficial effect OR healing OR intervention AND (2) sweet potato OR Ipomoea batatas OR traditional herb AND (3) blood glucose OR LDL OR lipid OR cholesterol OR dyslipidemia. Only articles published from 2011 onwards were selected for further analysis. This review includes the (1) method of intervention and the outcome (2) signaling mechanism involved (3) underlying mechanism of action, and the possible side effects observed based on the phytoconstiuents isolated. The comprehensive literature search retrieved a total of 2491 articles using the appropriate keywords. However, on the basis of the inclusion and exclusion criteria, only 23 articles were chosen for further review. The results from these articles indicate that I. batatas has proven to be effective in treating the hyperglycemic condition and is able to regulate dyslipidemia. Therefore, this systematic review summarizes the signaling mechanism, mechanism of action, and phytoconstituents responsible for those activities of I. batatas in treating hyperglycemic based on the in vitro and in vivo study.     

Mechanical and tribological properties of Ti/TiAlN duplex coatings on high and low alloy tool steels

In this research work, different steels were hardened using plasma nitriding process in an Arc-PVD device. Afterwards, on both non-nitrided and plasma nitrided substrates, different Ti/TiAlN multilayer coatings were deposited by a magnetron sputtering device. Scratch tests were performed on the duplex systems in order to characterize their adhesive properties. The failure modes of individual coating systems under various normal loads were described using light optical microscope. Furthermore, to study the effect of plasma nitriding on the friction coefficient and wear rate of the systems, ball-on-disc tests were carried out. It was shown that high and low alloy tool steels obtained different levels of hardness after plasma nitriding process. The results of scratch tests showed that both Ti/TiAlN multilayer coatings have a higher adhesion to plasma nitrided steels compared to non-nitrided steels. In addition, plasma nitriding of the substrates resulted in an increase in the wear rates of multilayer coatings. It was also revealed that the adhesion and the tribology of multilayers depend strongly on the amount of titanium interlayers. An increase of the thickness of titanium interlayers enhanced the adhesion of multilayers. However, increasing the thickness of titanium interlayers decreased the hardness and wear resistance of multilayers.     

Fabrication and electrochemical behavior of single-walled carbon nanotube/graphite-based electrode

An electrochemical method for determining the dihydroxybenzene derivatives on glassy carbon (GC) has been developed. In this method, the performance of a single-walled carbon nanotube (SWCNT)/graphite-based electrode, prepared by mixing SWCNTs and graphite powder, was described. The resulting electrode shows an excellent behavior for redox of 3,4-dihydroxybenzoic acid (DBA). SWCNT/graphite-based electrode presents a significant decrease in the overvoltage for DBA oxidation as well as a dramatic improvement in the reversibility of DBA redox behavior in comparison with graphite-based and glassy carbon (GC) electrodes. In addition, scanning electron microscopy (SEM) and atomic force microscopy (AFM) procedures performed for used SWCNTs.     

Surface modification and preparation of nanofiltration membrane from polyethersulfone/polyimide blend—Use of a new material (polyethyleneglycol‐triazine)

Blends of polyethersulfone/polyimide (PES/PI) were prepared by dissolving in dimethylformamide/dioxane (DMF/DO) to manufacture nanofiltration membranes by using polyvinylpirrolidone (PVP) as a pore former. The membrane modification was carried out by adding ethylenediamine (EDA) to open the imide group ring of PI and by using polyethyleneglycol (PEG)‐triazine, as a new modifier material, that was produced in the laboratory. This modification involves the formation of a covalence ‐C‐N‐ bound between PEG‐triazine and amine groups (according to addition‐elimination reactions) at different temperatures. After functionalizing the membranes, diethanolamine (DA) was utilized as a hydrophilic modifier to change the membranes properties. SEM, AFM, FTIR‐ATR, EDS (X‐ray analysis) and contact angle tests were carried out to characterize modified membranes. The hydrophilicity of PES/PI membranes was improved by modification. An increase in pure water flux (up to 195 kg/m² h) and a decline in NaCl rejection (from 25 to 16%) are largely influenced by diminishing the PES/PI ratio in L₁‐L₅ membranes (Category 1). In L₆, L₇, and L₈ membranes (Category 2), by introducing PEG‐triazine into the membrane recipe, salt rejection increased from 75 to 80%. Addition of DA further enhances the salt rejection up to 93%. Fluxes were approximately similar for membranes in Category 2. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Oestrogenic Regulation of Mitochondrial Dynamics

Biological sex influences disease development and progression. The steroid hormone 17β-oestradiol (E2), along with its receptors, is expected to play a major role in the manifestation of sex differences. E2 exerts pleiotropic effects in a system-specific manner. Mitochondria are one of the central targets of E2, and their biogenesis and respiration are known to be modulated by E2. More recently, it has become apparent that E2 also regulates mitochondrial fusion–fission dynamics, thereby affecting cellular metabolism. The aim of this article is to discuss the regulatory pathways by which E2 orchestrates the activity of several components of mitochondrial dynamics in the cardiovascular and nervous systems in health and disease. We conclude that E2 regulates mitochondrial dynamics to maintain the mitochondrial network promoting mitochondrial fusion and attenuating mitochondrial fission in both the cardiovascular and nervous systems.