Introduction of a pseudo demons force to enhance deformation range for robust reconstruction of super‐resolution time‐resolved 4 DMRI

Purpose The purpose of this study was to enhance the deformation range of demons‐based deformable image registration ( DIR ) for large respiration‐induced organ motion in the reconstruction of time‐resolved four‐dimensional magnetic resonance imaging ( TR ‐4 DMRI ) for multi‐breath motion simulation. Methods A demons‐based DIR algorithm was modified to enhance the deformation range for TR ‐4 DMRI reconstruction using the super‐resolution approach. A pseudo demons force was introduced to accelerate the coarse deformation in a multi‐resolution (n = 3) DIR approach. The intensity gradient of a voxel was applied to its neighboring (5 × 5 × 5) voxels with a weight of Gaussian probability profile ( σ  = 1 voxel) to extend the demons force, especially on those voxels that have little intensity gradience but high‐intensity difference. A digital 4 DMRI phantom with 3–8 cm diaphragmatic motions was used for DIR comparison. Six volunteers were scanned with two high‐resolution (highR: 2 × 2 × 2 mm 3 ) breath‐hold ( BH ) 3 DMR images at full inhalation ( BHI ) and full exhalation ( BHE ) and low‐resolution (lowR: 5 × 5 × 5 mm 3 ) free‐breathing ( FB ) 3 DMR cine images (2 Hz) under an IRB ‐approved protocol. A cross‐consistency check ( CCC ) ( BHI → FB ← BHE ), with voxel intensity correlation ( VIC ) and inverse consistency error ( ICE ), was introduced for cross‐verification of TR ‐4 DMRI reconstruction. Results Using the digital phantom, the maximum deformable magnitude is doubled using the modified DIR from 3 to 6 cm at the diaphragm. In six human subjects, the first 15‐iteration DIR using the pseudo force deforms 200 ± 150% more than the original force, and succeeds in all 12 cases, whereas the original demons‐based DIR failed in 67% of tested cases. Using the pseudo force, high VIC (>0.9) and small ICE (1.6 ± 0.6 mm) values are observed for DIR of BHI & BHE , BHI → FB , and BHE → FB . The CCC identifies four questionable cases, in which two cases need further DIR refinement, without missing true negative. Conclusions The introduction of a pseudo demons force enhances the largest deformation magnitude up to 6 cm. The cross‐consistency check ensures the quality of TR ‐4 DMRI reconstruction. Further investigation is ongoing to fully characterize TR ‐4 DMRI for potential multi‐breathing‐cycle radiotherapy simulation.

Spin–lattice relaxation studies on deep eutectic solvent/Choliniumtetrachloroferrate mixtures: Suitability of DES‐based systems towards magnetic resonance imaging studies

This study has been undertaken with an aim to investigate the suitability of the deep eutectic solvents (DES)‐based systems for magnetic resonance imaging studies. DESs are used to develop the systems, keeping in mind the fact that these are relatively less toxic than ionic liquids, and hence, DES based magnetic compound is expected to be relatively less toxic than magnetic ionic liquids. In this work, spin–lattice (T 1 ) relaxation measurements are carried out in the binary mixtures of deep eutectic solvent with a paramagnetic component choliniumtetrachloroferrate ([Ch][FeCl 4 ]). Two cholinium ion based DESs, namely ethaline and glyceline have been used for this study. For both ethaline/[Ch][FeCl 4 ] and glyceline/[Ch][FeCl 4 ], T 1 is observed to vary significantly with very low concentration of [Ch][FeCl 4 ]. Such an observation can arise due to the high degree of paramagnetic coupling between DESs and [Ch][FeCl 4 ]. The results advocate the suitability of both ethaline/[Ch][FeCl 4 ] and glyceline/[Ch][FeCl 4 ] mixture as a potential T 1 contrast agent. Interestingly, when the experiments are carried out in aqueous medium, significant lowering of T 1 of water proton with very low concentration of ethaline/[Ch][FeCl 4 ] and glyceline/[Ch][FeCl 4 ] is observed. This study demonstrates that the present systems can act as a suitable T 1 contrast agent.

Modified whale optimization algorithm for fractional‐order multi‐input SSSC‐based controller design

Summary In this paper, the design of a fractional‐order (FO) multi‐input–single‐output (MISO)–type static synchronous series compensator (SSSC) is proposed with a goal to improve the power system stability using modified whale optimization algorithm (MWOA). The proposed MWOA achieves an appropriate balance between exploitation and exploration stages of the original whale optimization algorithm. The performance of MWOA is validated by employing the benchmark test functions and further contrasted with whale optimization algorithm and other heuristic algorithms like gravitational search algorithm, particle swarm optimization, differential evolution, and fast evolutionary programming algorithms to demonstrate its strength. The proposed FO MISO SSSC controller is optimized by the MWOA technique and tested under single‐machine infinite bus system and further extended to a multi‐machine framework. To demonstrate the superiority of MISO‐type SSSC controller, the results obtained from it are compared with particle swarm optimization and differential evolution–based conventional single‐input–single‐output structured SSSC controllers. The comparison of results of MWOA with that of other methods validates its superiority in the present context.

Modeling of thermomechanical properties of polymeric hybrid nanocomposites

This article reports modeling of effective thermomechanical properties of multifunctional carbon nanotube (CNT)‐reinforced hybrid polymeric composites (hereafter, it is referred as “ fuzzy fiber composite ”). The novel constructional feature of fuzzy fiber composite (FFC) is that nanoscale CNTs are radially grown on the circumferential surfaces of microscale carbon fibers. Several micromechanical models were developed to predict the effective thermomechanical properties of FFC. The waviness of CNTs is intrinsic to many manufacturing processes and it influences thermomechanical behavior of two‐phase CNT‐reinforced composites. Therefore, an endeavor was also made to investigate the effect of wavy CNTs on the effective thermomechanical properties of FFC. The proposed modeling approach was applied to a heat exchanger made of FFC to determine its effective thermal conductivities. The findings of our study suggest that FFC containing nano‐ and micro‐scale fillers show improved thermomechanical properties and are promising next‐generation polymeric composites for advanced structural applications. POLYM. COMPOS., 39:4148–4164, 2018. © 2017 Society of Plastics Engineers

Effect of polyaniline‐coated carbon nanotube and nanosilver hybrid nanoparticles on the dielectric properties of poly(methyl methacrylate) nanocomposites

The polyaniline (PANI)‐coated functionalized multi‐walled carbon nanotubes (f‐CNTs) and silver nanoparticles (AgNPs) (PANI@f‐CNTs and PANI@AgNPs hybrid nanofillers) are synthesized by means of in situ polymerization of aniline monomer on the surface of f‐CNTs and AgNPs. The PANI@f‐CNTs and PANI@AgNPs hybrid nanofillers were successfully incorporated into the polymethyl methacrylate (PMMA) matrix through in situ polymerization of methyl methacrylate. The Fourier transform infrared spectroscopy analysis reveals that the existence of strong interfacial adhesive bonding between PANI@f‐CNTs and PANI@AgNPs hybrid nanofillers and PMMA matrix. The X‐ray diffraction (XRD) analysis indicates that there is no change in position of the diffraction peak as a result crystallinity of the samples are not much affected by the addition of hybrid nanofillers. The transmission electron microscopy and scanning electron microscopy analysis displayed that the phase morphology of the PMMA nanocomposites is significantly changed as well as hybrid nanofillers are homogeneously dispersed within the PMMA matrix. The AC conductivity ( σ ac ), dielectric permittivity ( ɛ ′) dielectric loss (tan δ ) of the PMMA nanocomposites are remarkably increases whereas the real impedance ( Z ′) decreases by the Incorporation of the hybrid nanofillers into the PMMA matrix, which concludes that the synthesized polymer materials have most promising dielectric application. POLYM. COMPOS., 39:E1294–E1305, 2018. © 2018 Society of Plastics Engineers

Charge transport and prototypical optical absorptions in functionalized zinc phthalocyanine compounds: A density functional study

Metal phthalocyanines are considered to be prominent candidates for designing organic semiconductors. However, enhancing n‐type characteristics and air stability in these compounds have been the major challenges. Earlier studies on zinc phthalocyanines (ZnPc) reported enhancement in electron mobility due to fluorination. We present a theoretical study of the charge transfer and optical properties of functionalized zinc phthalocyanines (XZnPc, with X = F 16 , Cl 16 , Br 16 , I 8 , and (CN) 8 ) within the framework of the density functional theory. Substitutions with electron‐withdrawing groups at the peripheral sites of ZnPc was found to lower both E HOMO and E LUMO in the compounds. Computed values of electron affinity (EA) > 3 eV in all XZnPcs indicated effective electron injection inferring enhanced n‐type characteristics and air stability in these compounds. However, cyanation ((CN) 8 ), as compared to the other EWGs, is found to enhance the electron mobility more prominently in the compound. In addition, studied optical absorption spectra of all XZnPc compounds at different exchange‐correlation functionals such as B3LYP, PBE0, CAM‐B3LYP, wB97xD, M06, and M06‐2X exhibited Q‐band in visible region (∼600‐700 nm) and B‐band (Soret) in ultraviolet (∼300‐400 nm) region, and a few shows an N‐band below 300 nm. Upon functionalization, the B‐band and Q‐band maxima show bathochromic shift both in gas phase and dimethyl sulfoxide. All these optical absorptions were found to be prototypical in nature, and the spectra are assigned to π → π ∗ character.

Anisotropic charge transport properties of chrysene derivatives as organic semiconductor: A computational study

We used density functional theory to calculate the angular resolution anisotropic charge mobility of the substituted chrysene molecules, viz, 4,10‐diphenoxychrysene (DPC), 4,10‐bis(phenylsulfanyl)chrysene (BPSC), and ethyl 8,9,12‐trimethoxychrysene‐6‐carboxylate (ETCC). The highest occupied molecular orbital–lowest unoccupied molecular orbital gap for DPC, BPSC, and ETCC was calculated to be 3.92, 3.83, and 3.81 eV, respectively, which inferred the compounds to be wide‐band‐gap semiconductors indicating that the compounds should have high stability in atmospheric conditions. The fact is also supported by electronic band‐structure calculation. In addition, higher electron affinity of studied compounds as compared with the bare chrysene molecule imparts enhancement of n‐type character in the compounds. The maximum hole ( μ Φ h ) and electron mobilities ( μ Φ e ) for DPC compound were found to be 0.739 cm 2 V −1 s −1 and 0.319 cm 2 V −1 s −1 , respectively, at Φ = 0°. On the other hand, in the case of BPSC crystal, comparatively larger anisotropic electron mobility (0.709 cm 2 V −1 s −1 at Φ = 0° and Φ = 179.90°) than the hole mobility (0.208 cm 2 V −1 s −1 at Φ = 127.19° and Φ = 307.10°) was noted. Similarly, in ETCC, the parallel dimers were found to contribute maximumμ Φ handμ Φ eof 0.052 and 0.102 cm 2 V −1 s −1 , respectively, at Φ = 0°. The substitution of ‐SPh in BPSC and ‐OCH 3 and ‐CO 2 CH 2 CH 3 in ETCC have relatively more impact on band reduction than ‐OPh in DPC, thus facilitating electron transport in BPSC and ETCC.

Direct synthesis of magnetron sputtered nanostructured Cu films with desired properties via plasma chemistry for their efficient antibacterial application

By changing the power density, the microstructure, surface morphology, surface energy, and electrical conductivity of the magnetron sputtered Cu films are tuned at a fixed Cu atomic content and the amount of Cu ion release. Data reveals that films with good crystallinity, low surface roughness, minimum surface energy, and the lowest electrical resistivity have shown a strong antibacterial response of Gram‐positive bacteria Staphylococcus aureus up to 90–96%. The correlation between the plasma chemistry and film properties is established to investigate the optimized film properties. A possible mechanism is hypothesized to elucidate the observed antibacterial property from the viewpoint of charge transfer.

Issue Information: Plasma Process. Polym. 9/2018

Silicon Solar Cells with Embedded Silicon‐on‐Insulation Layer via Nitrogen Ion Beam Implantation

In this research, silicon solar cells with embedded silicon‐on‐insulation layer obtained via nitrogen ion beam implantation are investigated. The embedded layer acts as a minority carrier‐blocking layer for the silicon solar cells, which results in the suppression of carrier recombination from the surface due to the formation of the silicon‐on‐insulation layer. This is achieved by integrating nitrogen ion implantation as a carrier reduction layer, which has a band offset asymmetry with silicon. The implantation is involved with the formation of surface defects by forming amorphous layers on Si surfaces. The electroluminescence images show that defects related to high energy nitrogen ion implantation are involved in the emission mechanism compared to low energy implanted nitrogen ion. From current–voltage analysis, the conversion efficiencies of nitrogen ion implanted cells are found lower than the reference cell, but the cell implanted with low energy nitrogen ion enhances the short circuit current density.