A Mathematical Description of the Kinetics of the Electrophoretic Deposition Process for Al2O3-Based Suspensions

The yield during electrophoretic deposition is modeled incorporating the changing electric field over the suspension, due to a potential drop over the growing deposit, assessed from on-line measurements of the current flowing through the deposition cell and the conductivity of the suspension during electrophoretic deposition. The kinetic model is validated for Al₂O₃ suspensions with different powder loads based on methylethylketone with n -butylamine and ethanol with polyethyleneimine or HNO₃, suspensions with, respectively, a constant and a decreasing electric field during deposition. The need for a powder concentration correction, even at volume fractions down to 0.03, and the incorporation of a changing electric field is experimentally proven to be essential in order to describe the deposition yield more accurately than predicted from the Hamaker equation.     

DNF sparsification and a faster deterministic counting algorithm

Given a DNF formula f on n variables, the two natural size measures are the number of terms or size s(f) and the maximum width of a term w(f). It is folklore that small DNF formulas can be made narrow: if a formula has m terms, it can be ${\epsilon}$ -approximated by a formula with width ${{\rm log}(m/{\epsilon})}$ . We prove a converse, showing that narrow formulas can be sparsified. More precisely, any width w DNF irrespective of its size can be ${\epsilon}$ -approximated by a width w DNF with at most ${(w\, {\rm log}(1/{\epsilon}))^{O(w)}}$ terms. We combine our sparsification result with the work of Luby & Velickovic (1991, Algorithmica 16(4/5):415–433, 1996) to give a faster deterministic algorithm for approximately counting the number of satisfying solutions to a DNF. Given a formula on n variables with poly(n) terms, we give a deterministic ${n^{\tilde{O}({\rm log}\, {\rm log} (n))}}$ time algorithm that computes an additive ${\epsilon}$ approximation to the fraction of satisfying assignments of f for ${\epsilon = 1/{\rm poly}({\rm log}\, n)}$ . The previous best result due to Luby and Velickovic from nearly two decades ago had a run time of ${n^{{\rm exp}(O(\sqrt{{\rm log}\, {\rm log} n}))}}$ (Luby & Velickovic 1991, in Algorithmica 16(4/5):415–433, 1996).     

Novel approach with polyfluorene/polydisulfide copolymer binder for high-capacity silicon anode in lithium-ion batteries

In this study, as a novel design with the collaboration of a fluorene and sulfide-based copolymer for Li-ion battery application is presented. Polyfluorene-co-polydisulfide is prepared with desired functional groups to yield a conductivity and good adhesion. These critical and important features are performed by preparing polymers with proper functional groups. The preparation process is accomplished via Suzuki coupling process under Pd catalyst by combining separately synthesized 4,4′-dibromodiphenyl disulfide in combination with 9,9-dioctylfluorene-2,7-bis(trimethylborate). The fully obtained capacity of the silicon particles, that is, at C/10 with the capacity of 1250 mAh g⁻¹ after the 500th cycle, approves the good performance by preserving capacity stability till 600th cycles. The designed and synthesized polymer binder with different functionalities and carbon nanotube additive show better characteristics such as conductivity, high polarity, and binding adhesion. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48303.     

19F MRI Nanotheranostics for Cancer Management: Progress and Prospects

Fluorine magnetic resonance imaging (¹⁹F MRI) is a promising imaging technique for cancer diagnosis because of its excellent soft tissue resolution and deep tissue penetration, as well as the inherent high natural abundance, almost no endogenous interference, quantitative analysis, and wide chemical shift range of the ¹⁹F nucleus. In recent years, scientists have synthesized various ¹⁹F MRI contrast agents. By further integrating a wide variety of nanomaterials and cutting-edge construction strategies, magnetically equivalent ¹⁹F atoms are super-loaded and maintain satisfactory relaxation efficiency to obtain high-intensity ¹⁹F MRI signals. In this review, the nuclear magnetic resonance principle underlying ¹⁹F MRI is first described. Then, the construction and performance of various fluorinated contrast agents are summarized. Finally, challenges and future prospects regarding the clinical translation of ¹⁹F MRI nanoprobes are considered. This review will provide strategic guidance and panoramic expectations for designing new cancer theranostic regimens and realizing their clinical translation.     

Synthesis and characterization of lithium calcium phosphate ceramics

The crystal structure, thermal, dielectrical, alternating current conductivity and microstructure properties of lithium calcium phosphate ceramics synthesized by the sol–gel method were investigated. The average crystallite size, crystallinity, activation energy and enthalpy of crystallization of Ca₁₀Li(PO₄)₇ ceramics were determined. The X-ray diffraction (XRD) results indicated that the apatitic structure belonging to HAp was transformed fully to Ca₁₀Li(PO₄)₇ phase with the addition of Li. The Avrami exponents of the samples suggest that the crystallization mechanism is based on the surface nucleation and one-dimensional growth. It was found that the alternating current conductivity mechanism of the ceramics is controlled by the hopping motion involving a translational motion with a sudden hopping. The dielectric constant of the samples shows a small increase with increasing amount of Li.     

Diffusion coefficients and phase equilibria of carbon dioxide–ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) system

This article presents the mutual diffusion coefficients of a carbon dioxide–ionic liquid, [bmim][PF₆], system at temperatures of 313.15 and 323.15 K and pressures of 5 and 8 MPa. In order to estimate the diffusion coefficients, we have carried out experiments to find time-dependent carbon dioxide solubilities in the ionic liquid and then fit a transport model to the data. In a system containing high pressure carbon dioxide and ionic liquid, carbon dioxide dissolves in the liquid until its equilibrium mole fraction is reached. During this process, the position of the liquid–vapour interface and the density of the liquid phase change. To account for the variation in liquid density, an equation fit to the experimental density data is included in the transport model. To track the moving interface, the volume-of-fluid method is used. The diffusivities at dilute concentration and at thermodynamic phase equilibrium are determined and compared with the literature values and those obtained from correlations.     

ZrB2–SiC composites prepared by reactive pulsed electric current sintering

Fully densified ZrB₂–20 vol% SiC composites were produced by reactive pulsed electric current sintering (PECS) of a powder mixture containing ZrH₂, B, SiC and B₄C within a total thermal cycle time of only 50 min. During the combined synthesis and sintering process, the ZrH₂ powder decomposed gradually from ZrH₂ into ZrH_m and finally metal Zr that reacted with elemental B to form the ZrB₂ matrix. Reducing the ZrH₂ particle size by attritor milling significantly enhanced densification and allowed initiation of self-propagating high temperature synthesis (SHS) during PECS. The PECS grades exhibited a slightly textured structure, with ≤17% of the ZrB₂ grains oriented with their (0 0 1) planes perpendicular to the direction of pressure and DC current. Because of the ZrB₂ grain orientation, anisotropic mechanical properties were observed. Ceramics prepared from attritor milled powders and PECS with a pressure applied after 5 min upon reaching 1900 °C achieved excellent flexural strengths of 901–937 MPa. The hardness and fracture toughness were respectively 19.7–19.8 GPa and 4.0–4.7 MPa m^1/2 in the direction parallel and 20.2–21.3 GPa and 3.8–3.9 MPa m^1/2 in the direction perpendicular to the applied pressure.     

Pipeline Flow Behavior of Water‐in‐Oil Emulsions with and without a Polymeric Additive in the Aqueous Phase

New experimental results are presented on the pipeline flow behavior of water‐in‐oil (W/O) emulsions with and without a polymeric additive in the aqueous phase. The emulsions were prepared from three different oils of different viscosities (2.5 mPa s for EDM‐244, 6 mPa s for EDM‐Monarch, and 5.4 mPa s for Shell Pella, at 25 °C). The W/O emulsions prepared from EDM‐244 and EDM‐Monarch oils (without any polymeric additive in the dispersed aqueous phase) exhibited drag reduction behavior in turbulent flow. The turbulent friction factor data of the emulsions fell well below the Blasius equation. The W/O emulsions prepared from EDM‐244 oil exhibited stronger drag reduction as compared with the EDM‐Monarch oil. The W/O emulsions prepared from Shell Pella oil exhibited negligible drag reduction in turbulent flow and their friction factor data followed the Blasius equation. The Shell Pella emulsions were more stable than the EDM‐244 and EDM‐Monarch emulsions. When left unstirred, the EDM‐244 and EDM‐Monarch emulsions quickly coalesced into separate oil and water phases whereas the Shell Pella emulsions took a significantly longer time to phase separate. The Shell Pella oil emulsions were also milkier than the EDM emulsions. The addition of a polymer to the dispersed aqueous phase of the W/O emulsions had a significant effect on the turbulent drag reduction behavior.