Metal microparticle – Polymer composites as printable,bio/ecoresorbable conductive inks

Biologically and environmentally resorbable electronic devices support application possibilities that cannot be addressed with conventional technologies. This paper presents highly conductive, water-soluble composites that can be printed to form contacts, interconnects, antennas, and other important features that are essential to nearly all systems of this type. An optimized material formulation involves in situ polymerization to yield a polyanhydride containing a dispersion of molybdenum microparticles at appropriate concentrations. Comparisons of essential physical and electrical properties of these materials to those of composites formed with other polymers and other metal microparticles reveal the relevant considerations. Various functional demonstrations of screen-printed test structures and devices illustrate the suitability of these conductive inks for use in water-soluble electronic devices. A key advantage of the material introduced here compared to alternatives is its ability to maintain conductance over significant periods of time while immersed in relevant aqueous solutions. Studies involving live animal models establish the biocompatibility.     

Phase-controlled synthesis of thermally stable nitrogen-doped carbon supported iron catalysts for highly efficient Fischer-Tropsch synthesis

Nano Research - Iron-based nanoparticles with uniform and high particle dispersion, which are supported on carbon structures, have been used for various applications. However, their preparation...     

Macroscopic Ag nanostructure array patterns with high-density hotspots for reliable and ultra-sensitive SERS substrates

Nano Research - Synthesis of metal nanostructures arrays with large amounts of small nano-gaps on a homogenous macroscale is of significant interest and importance in chemistry, biotechnology,...     

Increased mobility of an <Emphasis Type="Italic">α</Emphasis>-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> grain boundary by electron-beam irradiation

When subjected to electron-beam irradiation in a transmission electron microscope, the grain boundary in an α-Al₂O₃ bicrystal is observed to migrate even at room temperature. The bicrystal is composed of grains with the same normal direction, and thus the difference in strain energy or surface energy between the two grains cannot explain the observed migration. We attribute this phenomenon to an increase in grain boundary mobility by electron-beam irradiation, especially by radiolysis effects.     

Low Frequency Eddy Current Testing of Insulators and Composites

Eddy current testing (ECT), a non-destructive testing method widely used to evaluate defects within conductive materials, is explored in this study as it applies to insulators and non-uniformly conductive materials. Previous work has shown that at high frequencies, differences in electric permittivity can be detected with ECT. In this study, a new design of an ECT sensor that employs two resonance-tuned coils is evaluated. Results show that material inconsistencies in insulators are detectable due to spatial variations in permittivity and magnetic permeability, and that detection is possible at lower frequencies than previously demonstrated. In addition to determining signal dependence on individual electromagnetic parameters, sensitivity for defect detection in a carbon fiber-reinforced polymer (CFRP) composite is qualitatively determined. Although low signal-to-noise ratio is observed with a small-diameter coil, by increasing the coil diameter, the signal to noise ratio is increased while preserving adequate spatial resolution to detect defects in the sample. This study expands on previous studies of the application of ECT to insulators, and demonstrates that defect detection is possible in CFRPs.     

Biomedical applications of mRNA nanomedicine

As an attractive alternative to plasmid DNA, messenger RNA (mRNA) has recently emerged as a promising class of nucleic acid therapeutics for biomedical applications. Advances in addressing the inherent shortcomings of mRNA and in the development of nanoparticle-based delivery systems have prompted the development and clinical translation of mRNA-based medicines. In this review, we discuss the chemical modification strategies of mRNA to improve its stability, minimize immune responses, and enhance translational efficacy. We also highlight recent progress in nanoparticle-based mRNA delivery. Considerable attention is given to the increasingly widespread applications of mRNA nanomedicine in the biomedical fields of vaccination, protein-replacement therapy, gene editing, and cellular reprogramming and engineering.     

Peculiar Hole Doping by Ca Substitution in Cuprate Superconductors

The doping effect of Ca substitution in Y_0.7Ca_0.3Ba₂Cu₃O _y has been studied for y=6.9 and 6 by the x-ray absorption near edge spectroscopy (XANES). While Ca doping leads to an obvious increase in hole concentration in the CuO₂ planes in Y_0.7Ca_0.3Ba₂Cu₃O_6.9, XANES indicates absence of this doping effect in Y_0.7Ca_0.3Ba₂Cu₃O₆. These two contradict results suggest that the doping effect by Ca substitution could be sensitive to the oxygen content when y6.0. Comparisons with others' works are made.     

Slippery questions about complex fluids flowing past solids

Viscous flow is familiar and useful, yet the underlying physics is surprisingly subtle and complex. Recent experiments and simulations show that the textbook assumption of 'no slip at the boundary' can fail greatly when walls are sufficiently smooth. The reasons for this seem to involve materials chemistry interactions that can be controlled--especially wettability and the presence of trace impurities, even of dissolved gases. To discover what boundary condition is appropriate for solving continuum equations requires investigation of microscopic particulars. Here, we draw attention to unresolved topics of investigation and to the potential to capitalize on 'slip at the wall' for purposes of materials engineering.     

Minimal acceptable handling time intervals for lifting and lowering tasks

A laboratory study was conducted to determine the minimal acceptable handling time interval (MAHTI) for 4 h of endurance manual materials handling tasks using a psychophysical approach. Nine experienced male subjects were recruited to perform manual materials handling tasks with three load weights (10, 15, and 20 kg) and six ranges (floor to knuckle, FK; knuckle to floor, KF; knuckle to shoulder, KS; shoulder to knuckle, SK; floor to shoulder, FS; shoulder to floor, SF). Subjects were asked to adjust the handling time interval to the minimum that they could perform without becoming strained, uncomfortable, tired, weakened, overheated, or out-of-breath for 4 h of the endurance handling period. The results showed that the heavier load produced a larger MAHTI, and the overall descending sequence of MAHTI values for the six ranges was FS, KS, SF, FK, KF, and SK. The MAHTI for each lifting task was significantly higher than that of its corresponding lowering task (p<0.05). All MAHTI data were further verified by tests run on an additional nine subjects; this showed that the psychophysically determined MAHTIs were appropriate with no apparent underestimation.