RHEOLOGICAL CHARACTERIZATION OF NON-NEWTONIAN FLUIDS WITH A NOVEL VISCOMETER

A hydrostatic head viscometer and its novel viscosity equation were developed to determine flow characteristics of Newtonian and non-Newtonian fluids. The objective of this research is to test capabilities of the hydrostatic head viscometer and its novel non-Newtonian viscosity equation by characterizing rheological behaviors of well-known polyethylene oxide aqueous solutions as non-Newtonian fluids with 60 wt.% sucrose aqueous solution as a reference/calibration fluid. Non-Newtonian characteristics of 0.3–0.7 wt.% polyethylene oxide aqueous solutions were extensively investigated with the hydrostatic head viscometer and its non-Newtonian viscosity equation over a 294–306 K temperature range, a 0.14–40 Reynolds number range, and a 55–784 s^?1 shear rate range at atmospheric pressure. Dynamic viscosity values of 60 wt.% sucrose aqueous solution were determined with the calibrated hydrostatic head viscometer and its Newtonian viscosity equation over a 3–5 Reynolds number range at 299.15 K and atmospheric pressure and compared with the literature dynamic viscosity value.     

Rapidly cycled courses of high-dose alkylating agents supported by filgrastim and peripheral blood progenitor cells in patients with metastatic breast cancer

Our purpose was to determine the feasibility of a regimen of multiple, rapidly cycled courses of high-dose alkylating agents, including paired courses of escalating doses of thiotepa, supported by peripheral blood progenitor cells and filgrastim, in patients with responding stage IV breast cancer. The regimen consisted of two courses of cyclophosphamide (3.0 g/m2/course) followed by two courses of thiotepa (500-700 mg/m2/course). All courses were supported by filgrastim. Leukaphereses were performed after each cyclophosphamide course to harvest peripheral blood progenitors (PBPs) for use as rescue following thiotepa administration. The planned interval for all courses was 14 days. Forty-two patients were enrolled. Thirty-eight received all four courses, and four did not receive the second thiotepa cycle due to poor PBP mobilization. The maximum dose of thiotepa that was administered was 700 mg/m2 x 2. At this dose, one patient developed encephalopathy, which resolved over several weeks. The median number of days to an absolute neutrophil count of 0.5 x 10(9)/liter after PBP reinfusion for cycles 1 and 2 of thiotepa were 9 (range, 7-16) and 9 (range, 8-13) days, respectively. The corresponding values for platelet recovery to >20 x 10(9)/liter were 11 (range, 8-39) and 12 (range, 10-28) days, respectively. There were no treatment-related deaths. Hospitalization was required following 28 of 84 cyclophosphamide courses and 76 of 80 thiotepa courses. Four patients developed grade III-IV mucositis. The median interval between courses of treatment was 15 (range, 13-29) days. Of 19 patients who entered the protocol with measurable disease in partial response from prior therapy, 8 (42%) achieved complete response following the high-dose therapy. Nine (21%) of 42 remain progression free at a median follow-up of 28 (range, 20-32) months. Therefore, we concluded that the administration of multiple, rapidly cycled courses of high-dose alkylating agents is feasible.     

Finite element model updating using bees algorithm

In this paper the application of bees algorithm (BA) in the finite element (FE) model updating of structures is investigated. BA is an optimization algorithm inspired by the natural foraging behavior of honeybees to find food sources. The weighted sum of the squared error between the measured and computed modal parameters is used as the objective function. To demonstrate the effectiveness of the proposed method, BA is applied on a piping system to update several physical parameters of its FE model. To this end, the modal parameters of the numerical model are compared with the experimental ones obtained through modal testing. Moreover, to verify the performance of BA, it is compared with the genetic algorithm, the particle swarm optimization and the inverse eigensensitivity method. Comparison of the results indicates that BA is a simple and robust approach that could be effectively applied to the FE model updating problems.     

Variation-aware clock network buffer sizing using robust multi-objective optimization

Many engineering optimization problems include unavoidable uncertainties in parameters or variables. Ignoring such uncertainties when solving the optimization problems may lead to inferior solutions that may even violate problem constraints. Another challenge in most engineering optimization problems is having different conflicting objectives that cannot be minimized simultaneously. Finding a balanced trade-off between these objectives is a complex and time-consuming task. In this paper, an optimization framework is proposed to address both of these challenges. First, we exploit a self-calibrating multi-objective framework to achieve a balanced trade-off between the conflicting objectives. Then, we develop the robust counterpart of the uncertainty-aware self-calibrating multi-objective optimization framework. The significance of this framework is that it does not need any manual tuning by the designer. We also develop a mathematical demonstration of the objective scale invariance property of the proposed framework. The engineering problem considered in this paper to illustrate the effectiveness of the proposed framework is a popular sizing problem in digital integrated circuit design. However, the proposed framework can be applied to any uncertain multi-objective optimization problem that can be formulated in the geometric programming format. We propose to consider variations in the sizes of circuit elements during the optimization process by employing ellipsoidal uncertainty model. For validation, several industrial clock networks are sized by the proposed framework. The results show a significant reduction in one objective (power, on average 38 %) as well as significant increase in the robustness of solutions to the variations. This is achieved with no significant degradation in the other objective (timing metrics of the circuit) or reduction in its standard deviation which demonstrates a more robust solution.     

Photocatalytic properties of solution combustion synthesized ZnO powders using mixture of CTAB and glycine and citric acid fuels

Zinc oxide (ZnO) powders have been prepared by solution combustion synthesis method using combination of cetyltrimethylammonium bromide (CTAB) with glycine and citric acid fuels. The combustion behavior, phase evolution, microstructure, optical properties and photocatalytic performance were compared by thermal analysis, X-ray diffractometry, electron microscopy, and diffuse reflectance and photoluminescence spectrometry techniques at various fuel to oxidant ratios (??=?0.5, 0.75, 1 and 1.5). Single phase and well-crystalline ZnO powders were directly formed regardless of fuel type and fuel content. The higher specific surface area and pore volume of the as-combusted ZnO powders using mixture of CTAB and citric acid fuels increased with fuel content. The lower band gap energies (3.10–3.16?eV) of the as-combusted ZnO powders in the presence of glycine fuel were attributed to their lower crystallinity, as confirmed by higher visible emission in photoluminescence spectra. The higher photodegradation of methylene blue under ultraviolet light irradiation was achieved by the as-combusted ZnO powders by using CTAB-citric acid mixed fuels, due to their good crystallinity and higher specific surface area.     

Development of cloud point extraction for simultaneous extraction and determination of gold and palladium using ICP-OES

Cloud point method was applied for the simultaneous extraction and preconcentration of trace amounts of gold and palladium. The extraction of analytes was performed in the presence of 1,8-diamino-4,5-dihydroxy anthraquinone as chelating agent and Triton X-114 as a non-ionic surfactant. After phase separation, the surfactant-rich phase was diluted with concentrated HNO(3) (65%, w/w) and the analytes concentrations were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The variables affecting the complexation and extraction conditions were optimized and under the optimum conditions (i.e. pH 6.5, 2.2 x 10(-4) mol l(-1) chelating agent, 0.15% (w/v) of Triton X-114, equilibration temperature 55 degrees C, centrifuge at 3500 rpm), quantitative extraction of Au(III) and Pd(II) from 100 ml of the aqueous solution was performed. The calibration curves were linear in the range of 0.5-1000 microg l(-1) with detection limits of 0.5 and 0.3 microg l(-1) and the enrichment factors were 8.6 and 20.2 for Au and Pd, respectively. Also the precision (%RSD) for eight replicate determinations of the analytes was better than 5%. Finally, the proposed method was successfully applied for the determination of Au and Pd in mine stones and standard reference materials (SRM).     

Synthesis of Chitosan/Gelatin granule containing amine derivated octa(ammonium chloride) substituted Polyhedral Oligomeric Silsesquioxane and investigating its application as a drug carrier

In this work, we have prepared a new granule hydrogel composites of natural biocompatible polymeric chitosan and gelatin (C-G). The gelatin side groups (hydroxyl and carboxyl) can attach with amine groups of chitosan, which improve the interlink crosslinking in the final nanocomposites. The diameter of the granuls is around 3?mm to 6?mm. Furthermore, in order to reinforce the mechanical properties of granules, for the first time, octa(ammonium chloride) substituted Polyhedral Oligomeric Silsesquioxane (POSS-(NH₃⁺Cl^?)₈) has been used as a nanofiller in the structure of this nanocomposite. The effect of POSS-(NH₃⁺Cl^?)₈ on mechanical stability and swelling behavior of hydrogels has been investigated in three pH of 1.2, 7.4 and 9.5, respectively. Results demonstrate that the C-G/POSS-(NH₃⁺Cl^?)₈ granules in acidic pH has the maximum swelling percent. The encapsulation efficiency (EE) values for C-G granules in three pH of 1.2, 7.4 and 9.5 are obtained 65%, 58% and 53% and for C-G/POSS-(NH₃⁺Cl^?)₈ sample are 59%, 52% and 48%, respectively, which conform with the swelling behavior of these hydrogels. According to the obtained results from Metronidazole (MTZ) release, the as-synthesized hydrogels may have intrinsic ability in the controlled release of drugs. The as-prepared hydrogels are characterized via FT-IR, SEM, TGA and XRD analysis.     

Epoxy/alumoxane and epoxy/boehmite nanocomposites: cure behavior,thermal stability,hardness and fracture surface morphology

Functionalized nanostructures such as, boehmite, salicylate alumoxane (Sal-A) and p-hydroxybenzoate alumoxane (PHB-A), were studied in varying amounts with respect to curing behavior, thermal stability, hardness and fracture surface morphology of their corresponding epoxy-based nanocomposites, emphasizing on the dispersabilities of the nanostructures in the epoxy matrix and the potential mechanisms of the interactions between various species. TG–DTA, Vickers hardness test and SEM were used to characterize the composite specimens. Addition of nanostructures into the epoxy matrix accelerated the curing process. The experimental tests proved that Sal-A acted most effectively as a co-curing agent through the autocatalytic curing process of the epoxy resin and also produced the highest values of Vickers hardness in its corresponding nanocomposites. The presence of the nanostructures also lowered the heat of reaction in curing process with an exception of PHB-A containing nanocomposites. Thermal stability of the nanocomposites was improved due to existence of the functionalized nanostructures. Mechanisms are proposed for the possible interactions between various species, constructing the three types of nanocomposites, divided into positive and negative types. The functional groups on the surfaces of the nanostructures not only facilitated chemical interactions with the polymer matrix but also improved their dispersion in the epoxy matrix. Dispersability tendency of the nanostructures in the epoxy matrix was of the order: boehmite < PHB-A < Sal-A. Extent of agglomeration of the nanostructures in the epoxy matrix depended on the types of the functional groups on their surfaces and consequently, their interactions with the epoxy matrix and hardener.     

Different behaviors of metallocene and Ziegler–Natta catalysts in ethylene/1,5‐hexadiene copolymerization

The behaviors of three different catalyst systems, TiCl₄/MgCl₂, Cp₂ZrCl₂ and Cp₂HfCl₂, were investigated in ethylene/1,5‐hexadiene copolymerization. In the Fourier transform infrared spectra of the copolymers, cyclization and branching were detected for 1,5‐hexadiene insertion in the metallocene and Ziegler–Natta systems, respectively. DSC and viscometry analyses results revealed that copolymers with lower T_m and crystallinity and higher molecular weight were obtained with metallocene catalysts. The sequence length distribution of the copolymers was investigated by using the successive self‐nucleation and annealing thermal fractionation technique. The continuous melting endotherms obtained from successive self‐nucleation and annealing analysis were employed to get information about short‐chain branching, the branching dispersity index, comonomer content and lamella thickness in the synthesized copolymers. The results established that metallocene catalysts were much more effective than Ziegler–Natta catalysts in the incorporation of 1,5‐hexadiene in the polyethylene structure. Metallocene‐based copolymers had higher short‐chain branching and comonomer content, narrower branching dispersity index and thinner lamellae. Finally, the tendency of the employed catalysts in the 1,5‐hexadiene incorporation and cyclization reaction was explored via molecular simulation. The energy results demonstrated that, in comparison to Ziegler–Natta, metallocene catalysts have a much higher tendency to 1,5‐hexadiene incorporation and cyclization. © 2018 Society of Chemical Industry     

Application of phylogenetic microarray analysis to discriminate sources of fecal pollution

Conventional methods for fecal source tracking typically use single biomarkers to systematically identify or exclude sources. High-throughput DNA sequence analysis can potentially identify all sources of microbial contaminants in a single test by measuring the total diversity of fecal microbial communities. In this study, we used phylogenetic microarray analysis to determine the comprehensive suite of bacteria that define major sources of fecal contamination in coastal California. Fecal wastes were collected from 42 different populations of humans, birds, cows, horses, elk, and pinnipeds. We characterized bacterial community composition using a DNA microarray that probes for 16S rRNA genes of 59,316 different bacterial taxa. Cluster analysis revealed strong differences in community composition among fecal wastes from human, birds, pinnipeds, and grazers. Actinobacteria, Bacilli, and many Gammaproteobacteria taxa discriminated birds from mammalian sources. Diverse families within the Clostridia and Bacteroidetes taxa discriminated human wastes, grazers, and pinnipeds from each other. We found 1058 different bacterial taxa that were unique to either human, grazing mammal, or bird fecal wastes. These OTUs can serve as specific identifier taxa for these sources in environmental waters. Two field tests in marine waters demonstrate the capacity of phylogenetic microarray analysis to track multiple sources with one test.