In this study, Mg-substituted tricalcium phosphate (Mg-TCP) nanoparticles were synthesized by hydrothermal reactions of Mg-calcite mesocrystals from echinoderm skeletons. Following the biomineralization of echinoderms, Mg-calcite powder was synthesized via the solid-state transition of Mg-amorphous calcium carbonate prepared by a wet-chemical precipitation method, which can also be used to fabricate Mg-TCP. We illustrated that Mg-calcite with a certain level of Mg substitution led to the formation of Mg-TCP through the ion-exchange reactions in the hydrothermal system. Therefore, this study provides a new pathway for the synthesis of Mg-TCP nanoparticles.

We have successfully employed a charge transfer mechanism to convert carbon nanotube (CNT) powder into CNT flexible membrane with no binder. We have demonstrated the use of the CNT membranes as electrode in a stacked bipolar solid-state capacitor using grafoil as current collector that showed 80% capacitance retention over 10,000 cycles at 70 °C. The CNT membranes could have potential application in catalysis, photovoltaic, thermoelectric, and many others.

Optoplasmonic networks consisting of dielectric microsphere resonators and plasmonic nanoantennas in a morphologically well-defined on-chip platform support unique electromagnetic signatures that are hybrids of photonic whispering gallery modes and localized surface plasmon resonances. Here we explore the dependence of their near- and far-field responses on the key structural parameters, including the size of the gold nanoparticles forming the plasmonic elements, the separation between the microspheres, and the geometry of the chain. The high degree of structural flexibility, which is experimentally accessible through template guided self-assembly approaches, makes these optoplasmonic structures a unique electromagnetic material for tuning spectral shapes and intensities.

We present the study of the synthesis of (001) nickel oxide (NiO) epitaxial nanocrystals grown on (001) strontium titanate (SrTiO3) single crystal substrates. Pulsed laser deposition of the bismuth nickel oxide (BiNiO3, BNO) perovskite precursor followed by post-deposition processing is carried out to form the NiO nanocrystals. A detailed analysis of the dimensions of nanocrystals reveals that the morphology attained differs from the thermodynamically expected equilibrium shape. The deviations from the equilibrium shape are found to follow a systematic trend where the in-plane basal dimensions, that is, the length and width of the nanocrystals grown differ in discretized dimensions. This discretization suggests that for a given interfacial area of nanocrystals there are multiple stable basal rectangular geometries attainable.

The ability to manipulate matter on the nanometer length scale is an important scientific goal, and the progress in the field of colloidal nanocrystal (NC) growth in the past decades has opened avenue for controlled synthesis of nanoscale materials with many unique physical properties that could enhance existing technologies or give rise to entirely new technologic applications. At the center of the progress is ever-increasing understanding on molecular interactions within colloidal synthesis, in which nucleation and growth each plays a critical role in the control of size, shape, morphology, and structure of NCs. Semiconductor NCs in quantum confinement regime, referred to as quantum dots (QDs), highlight the importance of such control over geometric parameters, since QDs exhibit size- and shape-dependent optical properties. In this paper, we demonstrate important aspects that govern QDs growth in the context of (i) precursor conversion chemistry, and (ii) intermediate species including molecular complex and clusters. Advances in understanding the growth chemistry of QDs have proved the significance of how precursors decompose and produce intermediate species. We review recent progress in regards to the synthetic chemistry of colloidal QDs and discuss our perspective on challenges and promises in the controlled large-scale synthesis of QDs.

In this report, a facile system consisting of iron (III) meso-tetrakis(4-hydroxyphenyl)porphyrin-methylene blue dye hybrid immobilized on a disposable paper strip was used to detect and sense H2O2 in aqueous solutions via a low-cost pixelometric imaging technique. The new technology was employed to evaluate the level of H2O2 in a self-administering 30%-labeled commercial H2O2 disinfectant solution. The result showed that the concentration of H2O2 in the tested pharmaceutical sample solution deviated from the label by 92.37%. The current approach provides a simple low-cost resolution for the rapid detection and quantification of H2O2 in aqueous solution and pharmaceutical fluids.

Heterostructures consisting of two ferromagnetic oxides La0.7Ca0.3MnO3 (LCMO) and SrRuO3 (SRO) were epitaxially grown by pulsed laser deposition onto a silicon (Si) substrate buffered by SrTiO3 (STO)/MgO/TiN. The x-ray scans and electron-diffraction patterns reveal the epitaxial nature of all five layers. From transmission electron microscopy, the thicknesses of the LCMO and SRO layers were estimated to be ~100 and ~200 nm, respectively. The magnetic properties of individual SRO and LCMO layers are in good agreement with the previous studies reported for those individual layers deposited on lattice-matched substrates, such as STO. The LCMO/SRO heterostructures showed enhanced switching field (from 6008 to 7600 Oe), which may originate from the bulk part of the heterostructure. The ability to grow these multifunctional structures on Si provides a route for wafer scale integration with Si, in contrast to oxide substrates that are not suitable for CMOS integration for microelectronics and spintronics applications.

The deeper comprehension of biological phenomena has led to the pursuit of designing and architecting complex biological systems. This has been incorporated through the advances in bioprinting of artificial organs and implants even at the microscale. In addition, tissue modeling has been employed to understand and prevent malfunctional and detrimental mechanisms that lead to fatal diseases. Furthermore, the endeavor to convey the mechanical properties of both scaffolds and cells has enabled the unveiling of disease modeling and regenerative medicine. This paper aims to provide a brief review of the design, modeling and characterization of conventional and architected structures employed in bioengineering.

Operational lifetime is a critical performance parameter of organic electronic devices and can be cut short by multiple degradation mechanisms. One supposed cause is metal migration between the electrodes, which, however, is difficult to study independently of other failure modes. We present a setup, which excludes such competing processes and demonstrates that silver (Ag) electrochemical migration through organic optoelectronic materials occurs predominantly by cation transport. Metal dendrites form at the cathode, eventually causing short circuits between the electrodes. Lifetime studies with organic light-emitting diodes containing Ag electrodes suggest that results obtained with our setup can provide relevant information about degradation in real devices.

The development of new metalloplastic material from the combination of an alkaline-fused dehydrated glucose–copper (II) chloride, carbon soot, and polysulfone and the evaluation of its potential for the electrochemical detection of a pro-carcinogenic humic acid in water is reported. Excellent detection limit greater than 1 pico-part-per-million (order of 10–13 mg/L) was achieved, a value that proved to be first-of-its-kind till date. Transfer coefficients between 0.8 and 1.0 were realized. The new material showed some potential for splitting hydrogen peroxide to oxygen and thus may be explored for energy application in addition to its use as a water quality monitoring probe.

We have investigated the equilibrium conformation of Pt2Ru3 nanoparticles in the presence of H2 and CO mixture gas using density functional theory (DFT) and Monte Carlo (MC) simulation. A multiple linear regression equation was prepared using DFT results to calculate adsorption energy from the structural descriptors. Using the regression equation, MC simulations were employed to elucidate the equilibrated conformation of Pt2Ru3 particles at a finite temperature of H2/CO where CO concentration in the range 100–500 ppm. MC results indicate that CO/H2 coadsorption induced the rearrangement of alloying atoms and Pt/Ru ratio exposed to the surface decreases with the increase of CO concentration.

This research focuses toward calculating the thermal conductivity of pillared-graphene structures (PGS). PGS consists of graphene and carbon nanotubes (CNTs). These two materials have great potential to manage heat generated by nano- and microelectronic devices because of their superior thermal conductivities. However, the high anisotropy limits their performance when it comes to three-dimensional heat transfer. Nonequilibrium molecular dynamics (NEMD) simulations were conducted to study thermal transport of PGS. The simulation results suggest that the thermal conductivity along the graphene plane can reach up to 284 W/m K depending on PGS’ parameters while along the CNT direction, the thermal conductivity can reach 20 W/m K.

Metal oxide-based transistors can be fabricated by low-cost, large-area solution processing methods, but involve a trade-off between low processing temperature, facile charge transport and high-capacitance/low-voltage transistor gates. We achieve these simultaneously by fabricating zinc oxide and sodium-incorporated alumina (SA) thin films with temperature not exceeding 200 to 250 °C using aqueous and combustion precursors, respectively. X-ray reflectivity shows a compositionally distinct SA boundary layer forming near the substrate and that a portion of the SA is chemically removed during the subsequent semiconductor deposition. Improved etch resistance and reduced dielectric leakage was obtained when (3-glycidoxypropyl) trimethoxysilane was included in the SA precursor.

We used density functional theory to investigate the electrochemical CO2 reduction and competing hydrogen evolution reaction on model Au, Ag, Cu, Ir, Ni, Pd, Pt, and Rh nanoparticles. On the coinage metal, the free energy of adsorbed COOH, CO, and H intermediates generally becomes more favorable with decreasing particle size. This pattern was also observed on all transition metals with the binding of the intermediates observed to be stronger on almost all of these metals. Comparative studies of the reaction profile reveal that H2 evolution is the first reaction to be energetically allowed at zero applied bias.

A model is developed and implemented for load-controlled instrumented conical indentation of a brittle open-cell foam on a dense substrate. A survey of observations suggests that such indentations are typified by displacement excursions at small indentation loads, load-displacement variability, localized crushing, and a discrete to continuum transition at intermediate loads. The model includes all these effects as well as stiffening at large loads as the substrate is encountered. Direct quantitative comparison is made with measurements of a silica foam on a soda-lime glass substrate, strongly supporting the physical basis of the model.

A facile and low-cost method based for tension gradient self-assembly was developed to prepare polytetrafluoroethylene (PTFE) nanofiber coatings on stainless-steel fiber felts. The PTFE particles were used as building blocks and the self-assembly process was analyzed thoroughly. After being sintered, the PTFE particles were transformed into PTFE nanofibers. The felts coated with the PTFE nanofibers exhibited superhydrophobicity and superoleophilicity, and could separate a series of oil–water mixtures with high efficiency and good reusability. The coated felts also presented excellent chemical and thermal stabilities. Over all, this approach could easily fabricate ultra-robust oil–water separation materials suitable for industrial applications.

Gravity is commonly considered negligible when the surface tension is dominant; i.e., the Bond number is less than 1. In this paper, however, the authors present a technique in which drops slide over surfaces with zero effective gravity. Our study compared the sliding motion of water drops on hydrophilic and hydrophobic surfaces in scenarios: one in which effective gravity = 1 (1 g) and one in which it = 0 (0 g). The authors found that the lateral retention force was greater under 1 g than it was under 0 g. Also, the results showed that retention forces calculated by Furmidge equation are higher than the measured forces.

Applying sufficient tensile strain to Ge leads to a direct bandgap group IV semiconductor, which emits in the mid-infrared (MIR) wavelength range. However, highly strained-Ge cannot be directly grown on Si because of its large lattice mismatch. In this work, we have developed a process based on Ge micro-bridge strain redistribution intentionally landed to the Si substrate. Traction arms were then partially etched to keep locally strained-Ge micro-blocks. Large tunable uniaxial stresses up to 4.2% strain were demonstrated in Ge, which was bonded on Si. Our approach allows envisioning integrated strained-Ge on Si platform for MIR-integrated optics. Silicon photonics merge optical and electronic components that can be integrated together onto a single microchip.

The use of zinc nitride (Zn3N2) films as a transparent electrode in various electronic devices has attracted much attention owing to its high-carrier mobility. In this study, we investigate the influence of the sputtering process on structural, optical, and electrical properties of a Zn3N2 film deposited by reactive magnetron sputtering. The reactivity of nitrogen species can be improved by changing the type of sputtering gas. Compared with Ar or Ne sputtering gas, polycrystalline Zn3N2 films deposited using He sputtering gas have a larger grain size. The optical band gap of the Zn3N2 films varied from ~1.2 to 1.5 eV depending on the N2 flow ratio and type of sputtering gas. The maximum mobility was 91.1 cm2/Vs when the Zn3N2 film was deposited using Ar sputtering gas with an N2 flow ratio of 40%. The carrier density of Zn3N2 films deposited using Ar sputtering gas was notably higher than those deposited using Ne or He sputtering gas, and more oxygen atoms are considered to substitute into nitrogen sites, where oxygen is considered to be from the residual water vapor in the sputtering chamber.