Global optimization in property‐based interplant water integration

This article presents a new global optimization method for the interplant water integration based on properties to characterize streams with numerous components. The problem is formulated as an mixed‐integer non‐linear programming (MINLP) model based on a superstructure that involves all possible options of interest (i.e., reuse and recycle in the same and to other plants and a set of shared treatment units). This formulation exhibits multiple local minima, and to overcome this problem, this article proposes effective branching rules in addition to two new reformulations for the upper bound (integer feasible solution) and the lower limit (relaxed solution), which are incorporated into a spatial branch and bound procedure to handle the bilinear terms in the model. The objective consists in finding the configuration with the minimum total annual cost. Results show that the global optimal solution (involving significant reductions in the fresh water consumption) is reached in few iterations and short central processing unit (CPU) time. © 2012 American Institute of Chemical Engineers AIChE J, 59: 813–833, 2013     

Effects of the Use of Pore Formers on Performance of an Anode Supported Solid Oxide Fuel Cell

The effects of amount of pore former used to produce porosity in the anode of an anode supported planar solid oxide fuel cell were examined. The pore-forming material utilized was rice starch. The reduction rate of the anode material was measured by Thermogravimetric analysis to qualitatively characterize the gas transport within the porous anode materials. Fuel cells with varying amounts of porosity produced by using rice starch as a pore former were tested. The performance of the fuel cell was the greatest with an optimum amount of pore former used to create porosity in the anode. This optimum is believed to be related to a trade off between increasing gas diffusion to the active three-phase boundary region of the anode and the loss of performance because of the replacement of active three-phase boundary regions of the anode with porosity.     

Highly sensitive electrochemical sensor based on zirconium oxide-decorated gold nanoflakes nanocomposite 2,4-dichlorophenol detection

Journal of Applied Electrochemistry - In this study, a sensitive and selective electrochemical sensor based on a zirconia oxide-decorated gold nanoflake nanocomposite-modified glassy carbon...     

Filler Wetting in Miscible ESBR/SSBR Blends and Its Effect on Mechanical Properties

The selective wetting behavior of silica in emulsion styrene butadiene rubber (ESBR)/solution styrene butadiene rubber (SSBR) blends is characterized by the wetting concept, which is further developed for filled blends based on miscible rubbers. It is found that not only the chemical rubber–filler affinity but also the topology of the filler surface significantly influences the selective filler wetting in rubber blends. The nanopore structure of the silica surface has been recognized as the main reason for the difference in the wetting behavior of the branched ESBR molecules and linear SSBR molecules. However, the effect of nanopore structure becomes more significant in the presence of silane. It is discussed that the adsorption of silane on silica surface constricts the nanopore to some extent that hinders effectively the space filling of the nanopores by the branched ESBR molecules but not by the linear SSBR molecules. As a result, in silanized ESBR/SSBR blends the dominant wetting of silica surface by the tightly bonded layer of SSBR molecules causes a low‐energy dissipation in the rubber–filler interphase. That imparts the low rolling resistance to the blends similar to that of a silica‐filled SSBR compound, while the ESBR‐rich matrix warrants the good tensile behavior, i.e., good abrasion and wear resistance of the blends.

     

Subunit‐Specific Labeling of Ubiquitin Chains by Using Sortase: Insights into the Selectivity of Deubiquitinases

Information embedded in different ubiquitin chains is transduced by proteins with ubiquitin‐binding domains (UBDs) and erased by a set of hydrolytic enzymes referred to as deubiquitinases (DUBs). Understanding the selectivity of UBDs and DUBs is necessary for decoding the functions of different ubiquitin chains. Critical to these efforts is the access to chemically defined ubiquitin chains bearing site‐specific fluorescent labels. One approach toward constructing such molecules involves peptide ligation by sortase (SrtA), a bacterial transpeptidase responsible for covalently attaching cell surface proteins to the cell wall. Here, we demonstrate the utility of SrtA in modifying individual subunits of ubiquitin chains. Using ubiquitin derivatives in which an N‐terminal glycine is unveiled after protease‐mediated digestion, we synthesized ubiquitin dimers, trimers, and tetramers with different isopeptide linkages. SrtA was then used in combination with fluorescent depsipeptide substrates to effect the modification of each subunit in a chain. By constructing branched ubiquitin chains with individual subunits tagged with a fluorophore, we provide evidence that the ubiquitin‐specific protease USP15 prefers ubiquitin trimers but has little preference for a particular isopeptide linkage. Our results emphasize the importance of subunit‐specific labeling of ubiquitin chains when studying how DUBs process these chains.     

SBA-15-supported ionic liquid compounds containing silver salts: Novel mesoporous π-complexing sorbents for separating polyunsaturated fatty acid methyl esters

Novel π-complexing sorbents were prepared by covalently immobilizing ionic liquids (ILs) onto mesoporous SBA-15 using a one-pot sol–gel process followed by coating these SBA-15-supported IL compounds with silver salts. The mesoporous π-complexing sorbents were characterized by small angle X-ray scattering (SAXS), FTIR, TEM, SEM, nitrogen adsorption desorption isotherm, NMR, and nitrogen elemental analysis. Two advantages were obtained using these novel mesoporous π-complexing sorbents versus the traditional π-complexing sorbents formed by directly anchoring silver salts onto silica gel. (1) Higher extraction capacities were found. The extraction capacity for the polyunsaturated fatty acid methyl ester (PUFAME), methyl all-cis-5,8,11,14,17-eicosapentaenoate (20:5 or EPA), was 195 mg/g sorbent using the mesoporous AgBF₄/SBA-15 · IL · PF₆ sorbent. The capacity decreased to 121 mg/g sorbent with microporous complexing sorbent AgBF₄/SiO₂ · IL · PF₆. (2) Better reusability was also achieved. The supported IL phase immobilized and retained silver salt on SBA-15 due to the interaction between the ionic liquid’s imidazolium cations and silver ions. Eight successive sorption runs with the AgBF₄/SBA-15 · IL · PF₆ sorbent showed a satisfactory reusability. The traditional π-complexing sorbent has a silver salt directly anchored on silica without the supported ionic liquid phase. Higher silver leaching into organic solution occurred from the AgBF₄/SBA-15 sorbent determined by ICP-AES. The combined percentage (wt%) of the omega-3 PUFAMEs: 20:5 and methyl all-cis-4,7,10,13,16,19-docosahexaenoate (22:6 or DHA) stripped from the AgBF₄/SBA-15 · IL · PF₆ by 1-hexene was significantly enriched from 18% in the original cod liver oil to 90.5%.     

Dielectric and dynamic mechanical relaxation behavior of exfoliated nano graphite reinforced flouroelastomer composites

Dynamic mechanical analysis and dielectric relaxation spectra of exfoliated nano graphite reinforced flouroelastomer composites were used to study their relaxation behavior as a function of temperature (−80°C to +40°C) and frequency (0.01 to 10⁵ Hz). The effect of filler loadings on glass transition temperature was marginal for all the composites and T_g value was in the narrow range of 7.8–8.4°C, which has been explained on the basis of relaxation dynamics of polymer chains in the vicinity of fillers. Strain‐dependent dynamical parameters were evaluated at dynamic strain amplitudes of 0.01–10%. The nonlinearity in storage modulus has been explained on the concept of filler‐polymer interaction and filler aggregation of the nano graphite platelets. The variation in real and complex part of impedance with frequency has been studied as a function of filler. The percolation of the nano graphite as studied by conductivity measurements is also reported. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers.     

Erratum to: On the reduction of gloss property of organic coated sheet metals after forming

Organic coated sheet metals (OCSM) are widely used in many industrial applications such as automobile or electrical appliances because of their corrosion resistance and satisfaction of ecological requirements. Nevertheless, original functions of the very thin coating layer in OCSM products may be altered after being formed which consequently leads to a reduction of the product’s quality. This paper deals with the reduction of gloss property of OCSM products. A forming limit diagram (FLD), a forming limit diagram of the coating layer (FLDC) of OCSM and a forming diagram for the prediction of gloss reduction are determined by using Nakajima tests. The Nakajima tests are performed with predefined strain states of the specimen. The experimental results show the dependency of the FLDC curve and the gloss reduction on both the equivalent strain and the strain ratio. Deep-drawing tests prove the applicability of the determined forming diagrams to predict coating fracture and gloss properties of OCSM after sheet metal forming and, thus, their potential as a tool for the process design for OCSM products.     

Multi-objective optimization of circular magnetic abrasive polishing of SUS304 and Cu materials

In this paper, a Multi-objective particle swarm optimization algorithm (MOPSOA) is applied to optimize surface roughness of workpiece after circular magnetic abrasive polishing. The most important parameters of polishing model, namely current, gap between pole and workpiece, spindle speed and polishing time, were considered in this approach. The objective functions of the MOPSOA depend on the quality of surface roughness of polishing materials with both simultaneous surfaces (Ra1, Ra2), which are determined by means of experimental approach with the aid of circular magnetic field. Finally, the effectiveness of the approach is compared between the optimal results with the experimental data. The results show that the new proposed polishing optimization method is more feasible.