Novel materials in magnetic resonance imaging: high permittivity ceramics,metamaterials, metasurfaces and artificial dielectrics

This article reviews recent developments in designing and testing new types of materials which can be: (i) placed around the body for in vivo imaging, (ii) be integrated into a conventional RF coil, or (iii) form the resonator itself. These materials can improve the quality of MRI scans for both in vivo and magnetic resonance microscopy applications. The methodological section covers the basic operation and design of two different types of materials, namely high permittivity materials constructed from ceramics and artificial dielectrics/metasurfaces formed by coupled conductive subunits, either in air or surrounded by dielectric material. Applications of high permittivity materials and metasurfaces placed next to the body to neuroimaging and extremity imaging at 7 T, body and neuroimaging at 3 T, and extremity imaging at 1.5 T are shown. Results using ceramic resonators for both high field in vivo imaging and magnetic resonance microscopy are also shown. The development of new materials to improve MR image quality remains an active area of research, but has not yet found significant use in clinical applications. This is mainly due to practical issues such as specific absorption rate modelling, accurate and reproducible placement, and acceptable size/weight of such materials. The most successful area has been simple “dielectric pads” for neuroimaging at 7 T which were initially developed somewhat as a stop-gap while parallel transmit technology was being developed, but have continued to be used at many sites. Some of these issues can potentially be overcome using much lighter metasurfaces and artificial dielectrics, which are just beginning to be assessed.

     

A Quantum Many-Body Density Matrix Model for Sub-Femtosecond Transport in Mesoscopic Structures

Transient regime relaxation in nanostructures is governed by the two-way information exchange between the active region and the contacts. In this paper, we introduce a second order quantum master equation for the active region’s many-body reduced density matrix, which includes the information exchange between the active region and the contacts, while eliminating the contacts explicitly from the simulation. For the case of a resonant-tunneling diode, the master equation is solved numerically. Proper injection from/into the contacts is obtained, and natural oscillations of the current and the number of particles in the well are observed, with a frequency in the mid-terahertz regime.     

The study of perceived adverse effects of digital piracy and involvement: insights from adult computer users

In this study, we focus on two sets of expected negative consequences of engaging in digital piracy among the seldom studied adult computer users rather than student population. We delve into the role of perceived risk and moral intensity as drivers of consumers’ attitudes and behavioural intentions, and explore the rarely examined moderating effect of issue involvement on the relationship between the attitude and intention to pirate. The dominant attitude–behaviour theory is extended with an ethical decision-making theoretical perspective. The hypotheses are tested via mail survey data from a random sample of adult consumers using structural equations modelling. The results of this cross-sectional study show unfailing support for the relationships proposed in our model. Our findings suggest that, in addition to perceived risk, moral intensity (i.e. the expected consequences for others), has a particularly strong total effect on the intention to pirate, and that consumer involvement in illegally downloading files is a salient factor moderating the relationship between attitudes and behavioural intentions. Based on this pattern of results, we offer theoretical and practical implications.     

Bright light effects on ultradian rhythms in performance on hemisphere-specific tasks

Ultradian rhythms in indices of brain hemisphere activity and in cognitive performance have been found in numerous studies. Asymmetry of these rhythms with regard to phase and frequency have also been documented in some studies. There is some evidence that bright light can affect ultradian rhythms of arousal state and vigilance. A study on unilateral exposure to bright light has demonstrated more pronounced effects of bright light on the right hemisphere. The aim of this study was to examine whether daytime intermittent bright light could affect parameters of ultradian rhythms in performance speed on hemisphere-specific tasks, and whether the effect of bright light was symmetric for the rhythms in performance on hemisphere-specific tasks presented laterally. A counter-balanced, within-subject research design was applied. The performance of 15 participants on hemisphere-specific tasks exposed laterally was measured every 30 min starting at 08:00 h and ending at 20:30 h in intermittent bright light (IBL, pulses of 15 min of 4000 lux light regularly interspersed between 45 min of background light levels of 300 lux) and in ordinary room light (ORL) conditions (300 lux). Individual time series data were subjected to cosinor analysis. General linear model analyses (the factors were: level of processing, visual field, and the task) were performed on the rhythms’ parameters. There was a substantial lengthening of the rhythms’ periods in IBL conditions for performance speed on spatial tasks and an increase in amplitude of the rhythms of performance speed for spatial tasks in both visual fields and for verbal tasks in the left visual field in the IBL conditions when compared to the ORL conditions. The results showed that the schedule of light exposure affected ultradian rhythms of hemisphere-specific tasks differently and that the right hemisphere seems to be more “sensitive” to light than the left hemisphere.     

Bipolar nanofiltration membranes based on plasma modified microfilters

Track‐etched membranes were used as support for deposition of plasma polymerized layers and formation of bipolar nanofiltration membranes. The 75 KHz plasma reactor was applied for that purpose. Three kinds of monomers were plasma polymerized. They were as follows: n‐butylamine, allylamine, and acrylic acid. For each monomer, the best polymerization parameters were selected. It was determined that acrylic acid deposited at the highest rate, then deposited allyloamine and finally n‐butylamine. Among the electrodes, the grounded one offered more stable layer and can be used for plasma polymer deposition. The obtained membranes showed good rejection properties toward bivalent ions. It was shown that the sequence of deposited layers did not affect the separation properties. For some investigated membranes, rejection reached 50–80% value. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39790.     

Influence of phosphorous-based flame retardants on the mechanical and thermal properties of recycled PC/ABS copolymer blends

The effects of three commercial aryl phosphate flame retardants (FRs; bisphenol A bis(diphenyl diphosphate) [BDP], triphenyl phosphate (TPP), and a proprietary oligomeric phosphate ester (OPE)) and a compatibilizer (methacrylate-butadiene-styrene copolymer [MBS]) on the thermal and mechanical properties of FR-recycled PC/acrylonitrile-butadiene-styrene copolymer (r-PC/r-ABS) blends are investigated. The addition of FRs to r-PC/r-ABS blends increases the storage, tensile, and flexural moduli, indicating a reinforcing effect. However, at elevated temperatures, FRs reduce the glass transition temperature and act as plasticizers. The thermal stability of r-PC/r-ABS/FR blends at 10% mass loss increases in the following order: r-PC/r-ABS/TPP < r-PC/r-ABS/BDP < r-PC/r-ABS/OPE < r-PC/r-ABS/OPE/MBS. Kinetics of thermal decomposition of the FR r-PC/r-ABS blends is studied calculating the thermal decomposition activation energies by the Flynn–Wall–Ozawa method. Scanning electron microscopy shows that r-PC/r-ABS/OPE blend is only partly miscible, while homogeneous structure is formed in the r-PC/r-ABS/OPE/MBS blend, which is supported by its good mechanical and thermal properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48377.     

江西建筑卫生陶瓷技术预见

依据技术预见理论，并运用德尔菲法、综合分析法等方法对建筑卫生陶瓷的国内外发展趋势和特点及江西省相关陶瓷领域的优劣势进行系统分析和预见，在此基础上提出了江西建筑卫生陶瓷发展重点方向和关键项目建议，同时为建筑卫生陶瓷领域的总体战略发展提出实施措施及政策建议。     

Identification and Characterization of Phospholipids with Very Long Chain Fatty Acids in Brewer’s Yeast

Yeast lipids and fatty acids (FA) were analyzed in Saccharomyces pastorianus from seven breweries and in the dietary yeast supplement Pangamin. GC–MS identified more than 30 FA, half of which were very‐long chain fatty acids (VLCFA) with hydrocarbon chain lengths of ≥22 C atoms. Positional isomers ω‐9 and ω‐7 were identified in FA with C18–C28 even‐numbered alkyl chains. The most abundant ω‐7 isomer was cis‐vaccenic acid. The structure of monounsaturated FA was proved by dimethyl disulfide adducts (position of double bonds and cis geometric configuration) and by GC–MS of pyridyl carbinol esters. Ultra‐high performance liquid chromatography‐tandem mass spectrometry with negative electrospray ionization identified the phospholipids phosphatidylethanolamine, phosphatidylinositol and phosphatidylcholine, with more than 150 molecular species. Wild‐type unmutated brewer's yeast strains conventionally used for the manufacture of food supplements were found to contain VLCFA.