A 3D unsplit-advection volume tracking algorithm with planarity-preserving interface reconstruction

A new volume tracking method is introduced for tracking interfaces in three-dimensional (3D) geometries partitioned with orthogonal hexahedra. The method approximates interface geometries as piecewise planar, and advects volumes in a single unsplit step using fully multidimensional fluxes that have their definition based in backward-trajectory remapping. By using multidimensional unsplit advection, the expense of high-order interface reconstruction is incurred only once per timestep. Simple departures from strict backward-trajectory remapping remove any need for consideration of volume computations involving shapes consisting of non-planar ruled surfaces. Second-order accuracy of the method is demonstrated even for vigorous 3D deformations.     

Practical tradeoffs between noise, quantitation, and number of iterations for maximum likelihood-based reconstructions

Emission computerised tomography images reconstructed using a maximum likelihood-expectation maximization (ML)-based method with different reconstruction kernels and 1-200 iterations are compared to images reconstructed using filtered backprojection (FBP). ML-based reconstructions using a single pixel (SP) kernel with or without a sieve filter show no quantitative advantage over FBP except in the background where a reduction of noise is possible if the number of iterations is kept small (<50). ML-based reconstructions using a Gaussian kernel with a multipixel full-width-at-half-maximum (FWHM) and a large number of iterations (200) require a sieve filtering step to reduce the noise and contrast overshoot in the final images. These images have some small quantitative advantages over FBP depending on the structures being imaged. It is demonstrated that a feasibility stopping criterion controls the noise in a reconstructed image, but is insensitive to quantitation errors, and that the use of an appropriate overrelaxation parameter can accelerate the convergence of the ML-based method during the iterative process without quantitative instabilities.     

Experimental study of splash generation in a flash smelting furnace

A survey of previous studies of splash formation in metallurgical vessels revealed that little information is available to characterize and describe the processes involved in splash formation. An experimental study of splash formation by top submerged gas injection was carried out in the settler region of the nickel flash smelting furnace at the Kalgoorlie Nickel Smelter (KNS) both to obtain some visualization of the splash mechanisms that occur on a plant scale and to measure the amount of splash being formed. Video images taken of the splashing showed that large sheets of melt were formed by the escaping gas and subsequently thinned into ligaments which then broke up into large splash drops. The video could only resolve a minimum size of 2 cm. The large splash drops visible on video have an initial velocity between 1 and 2 m/s, are unstable, and fall back into the bath after traveling a short distance. The analysis identified two major splash forming mechanisms. First, the gas injected resulted in the bulk movement of the melt to form a cavity and large sheets of melts being thrown around the point of injection. The area affected by this splash mechanism can be predicted successfully by using an energy balance between the removal of the melt in the cavity and the energy of the gas being injected. Second, the slag free surface within the cavity is highly unstable, and through the Kelvin-Helmholtz instability mechanism, small splash droplets are generated which are carried into the furnace’s top space. A model proposed for the formation of the smaller splash droplets predicted that the splash collected decreases exponentially with increasing height above the slag free surface from the point of splashing, and this is in agreement with the experimental results obtained.     

Synthesis, characterization and photopolymerization of vinyl ether and acrylate functionalized hybrid oligo-caprolactone

Linear vinyl ether-(oligo-caprolactone)-acrylate (VPCLA), combining fast free radical and complete cationic photopolymerizable groups, was synthesized, functionalized, and photopolymerized to produce polycaprolactone (PCL) network. Fourier Transform Infrared (FTIR) spectra confirmed that the C = C peaks from both vinyl ether and acrylate end groups were consumed after photopolymerization. Kinetics parameters obtained from differential scanning photo-calorimetry (DPC) analysis showed that photopolymerization of VPCLA at early stage was accelerated as the time needed to reach peak maximum was shortened, and the induction time was significantly shortened compared to monofunctional vinyl ether-(oligo-caprolactone) (VPCL). The activation energy (E_a) was calculated to be 14 kJ/mol, assuming second-order autocatalytic model was followed. Rate of polymerization of the hybrid oligomers was doubled in dual photoinitiators system, which contained both cationic and radical photoinitiators. Furthermore, the conversion was greatly improved at the presence of divinyl ether/hydroxybutyl vinyl ether in 1:1 ratio.     

Highly Sensitive Electro‐Plasmonic Switches Based on Fivefold Stellate Polyhedral Gold Nanoparticles

Electron–photon coupling in metal nanostructures has raised a new trend for active plasmonic switch devices in both fundamental understanding and technological applications. However, low sensitivity switches with an on/off ratio less than 5 have restricted applications. In this work, an electrically modulated plasmonic switch based on a surface‐enhanced Raman spectroscopy (SERS) system with a single fivefold stellate polyhedral gold nanoparticle (FSPAuNP) is reported. The reversible switch of the SERS signal shows high sensitivity with an on/off ratio larger than 30. Such a high on/off ratio arises primarily from the plasmonic resonance shift of the FSPAuNP with the incident laser due to the altered free electron density on the nanoparticle under an applied electrochemical potential. This highly sensitive electro‐plasmonic switch may enable further development of plasmonic devices.     

Ge-Rich (70%) SiGe Nanowire MOSFET Fabricated Using Pattern-Dependent Ge-Condensation Technique

A top-down approach of forming SiGe-nanowire (SGNW) MOSFET, with Ge concentration modulated along the source/drain (Si_0.7Ge_0.3) to channel (Si_0.3Ge_0.7) regions, is presented. Fabricated by utilizing a pattern-size-dependent Ge-condensation technique, the SGNW heterostructure PMOS device exhibits 4.5times enhancement in the drive current and transconductance (G_m) as compared to the homojunction planar device (Si_0.7Ge_0.3). This large enhancement can be attributed to several factors including Omega-gated nanowire structure, enhanced hole injection efficiency (due to valence band offset), and improved hole mobility (due to compressive strain and Ge enrichment in the nanowire channel).     

Spatially Probed Plasmonic Photothermic Nanoheater Enhanced Hybrid Polymeric–Metallic PVDF‐Ag Nanogenerator

Surface plasmon‐based photonics offers exciting opportunities to enable fine control of the site, span, and extent of mechanical harvesting. However, the interaction between plasmonic photothermic and piezoresponse still remains underexplored. Here, spatially localized and controllable piezoresponse of a hybrid self‐polarized polymeric‐metallic system that correlates to plasmonic light‐to‐heat modulation of the local strain is demonstrated. The piezoresponse is associated to the localized plasmons that serve as efficient nanoheaters leading to self‐regulated strain via thermal expansion of the electroactive polymer. Moreover, the finite‐difference time‐domain simulation and linear thermal model also deduce the local strain to the surface plasmon heat absorption. The distinct plasmonic photothermic–piezoelectric phenomenon mediates not only localized external stimulus light response but also enhances dynamic piezoelectric energy harvesting. The present work highlights a promising surface plasmon coordinated piezoelectric response which underpins energy localization and transfer for diversified design of unique photothermic–piezotronic technology.     

[Carboxyl‐11C]Labelling of Four High‐Affinity cPLA2α Inhibitors and Their Evaluation as Radioligands in Mice by Positron Emission Tomography

Cytosolic phospholipase A2α (cPLA2α) may play a critical role in neuropsychiatric and neurodegenerative disorders associated with oxidative stress and neuroinflammation. An effective PET radioligand for imaging cPLA2α in living brain might prove useful for biomedical research, especially on neuroinflammation. We selected four high‐affinity (IC₅₀ 2.1–12 nm ) indole‐5‐carboxylic acid‐based inhibitors of cPLA2α, namely 3‐isobutyryl‐1‐(2‐oxo‐3‐(4‐phenoxyphenoxy)propyl)‐1H‐indole‐5‐carboxylic acid ( 1 ); 3‐acetyl‐1‐(2‐oxo‐3‐(4‐(4‐(trifluoromethyl)phenoxy)phenoxy)propyl)‐1H‐indole‐5‐carboxylic acid ( 2 ); 3‐(3‐methyl‐1,2,4‐oxadiazol‐5‐yl)‐1‐(2‐oxo‐3‐(4‐phenoxyphenoxy)propyl)‐1H‐indole‐5‐carboxylic acid ( 3 ); and 3‐(3‐methyl‐1,2,4‐oxadiazol‐5‐yl)‐1‐(3‐(4‐octylphenoxy)‐2‐oxopropyl)‐1H‐indole‐5‐carboxylic acid ( 4 ), for labelling in carboxyl position with carbon‐11 (t_1/2=20.4 min) to provide candidate PET radioligands for imaging brain cPLA2α. Compounds [¹¹C] 1 – 4 were obtained for intravenous injection in adequate overall yields (1.1–5.5 %) from cyclotron‐produced [¹¹C]carbon dioxide and with moderate molar activities (70–141 GBq μmol^?1) through the use of Pd⁰‐mediated [¹¹C]carbon monoxide insertion on iodo precursors. Measured logD_7.4 values were within a narrow moderate range (1.9–2.4). After intravenous injection of [¹¹C] 1 – 4 in mice, radioactivity uptakes in brain peaked at low values (≤0.8 SUV) and decreased by about 90 % over 15 min. Pretreatments of the mice with high doses of the corresponding non‐radioactive ligands did not alter brain time–activity curves. Brain uptakes of radioactivity after administration of [¹¹C] 1 to wild‐type and P‐gp/BCRP dual knock‐out mice were similar (peak 0.4 vs. 0.5 SUV), indicating that [¹¹C] 1 and others in this structural class, are not substrates for efflux transporters.