We report on the low-temperature electrical characterization of bilayer MoS2 treated with increasing dose of oxygen:argon (1:3) plasma. We characterize the effective Schottky barrier heights as a function of plasma exposure time and observe a significant barrier lowering, with no accompanying p-type conduction in the negative bias region. Furthermore, we observe a crossover in the temperature-dependent conduction regimes below 181 K due to the plasma exposure. The Efros–Shklovskii (ES) hopping regime is seen to transform upon plasma exposure to a mixed ES/thermally-activated regime at high temperatures, and to a strongly short-range Arrhenius regime at low temperatures. We attribute the observed crossovers to a critical defect density created by the surface reaction with the plasma.

In in vitro separate compartment model of neuronal cells and extracellular iron oxide nanoparticles (IONs)–amyloid complexes, a traversing proton-induced Coulomb nanoradiator effect (CNR) was found to break up the ION–amyloid fibrils and to induce redox changes in the IONs. We found that the CNR effect caused the conversion of redox-active iron (II) into redox-inactive iron (III) as well as the disruption of the ION–amyloid fibrils without significantly damaging normal neuronal cells. Our observations suggest a non-invasive redox inactivation and β-amyloidolyis-based therapy of neurotoxic Aβ plaque involving a traversing proton Coulomb nanochelator that would not substantially impact normal neuronal cells.

Using time-resolved laser-scanning confocal microscopy and ultrafast optical pump/THz probe spectroscopy, we measure photoluminescence (PL) and THz-conductivity in perovskite micro-crystals and films. PL quenching and lifetime variations occur from local heterogeneity. Ultrafast THz-spectra measure sharp quantum transitions from excitonic Rydberg states, providing weakly bound excitons with a binding energy of ~13.5 meV at low temperatures. Ab-initio electronic structure calculations give a direct band gap of 1.64 eV, a dielectric constant of ~18, heavy electrons, and light holes, resulting in weakly bound excitons, consistent with the binding energies from the experiment. The complementary spectroscopy and simulations reveal fundamental insights into perovskite light-matter interactions.

To evaluate whether the photocatalysis efficiency of titanium oxide (TiO2) increases under the shading of carbon aerogel (CA), super black CA/TiO2 composite sheets were directly fabricated by physical mixing of CA, TiO2 powder, and binder. It was found that the photocatalysis efficiency of composite sheets were higher than that of pure TiO2 sheet. We attribute this phenomenon to the hot electrons coupling between CA and TiO2. Besides the direct light absorption of TiO2, the hot electrons generating and indirect energy transfer from CA to TiO2 may enhance the photocatalysis efficiency of TiO2.

Here, we report thiol-free thermal-injection synthesis of chalcopyrite (CuFeS2) nanocrystals (NCs) using iron (II) bromide (FeBr2), copper (II) acetaylacetonate (Cu(acac)2), and elemental sulfur (S). Controlled reaction temperature and growth time yield stable and phase-pure ternary CuFeS2 NCs exhibiting tetragonal crystal structure. With increasing growth time from 1 to 30 min, absorption peak slightly red shifts from 465 to 490 nm. Based on spectroscopic ellipsometry analysis, three electronic transitions at 0.652, 1.54, and 2.29 eV were found for CuFeS2 NC film. Also, CuFeS2 NC thin films are incorporated as hole transport layers in cadmium telluride solar cells reaching an efficiency of ~12%.

We have studied the effect of hydrostatic pressure on the confined exciton in a spherical core–shell quantum dot. Using a simple variational approach under the framework of effective mass approximation, we have computed the excitonic binding energy as a function of the shell thickness under the applied hydrostatic pressure. Our results show that the ground state binding energy of exciton depends greatly on the shell thickness, which tends to the two-dimensional limit of 4RX, when the ratio a/b tends to unity. The numerical calculations also suggest that the applied hydrostatic pressure favors the attraction between electrons and holes so the excitonic binding energy increases when pressure increases.

We provide insights pertaining the dependence of undercooling in the formation of graphite, nanodiamonds, and Q-carbon nanocomposites by nanosecond laser melting of diamond-like carbon (DLC). The DLC films are melted rapidly in a super-undercooled state and subsequently quenched to room temperature. Substrates exhibiting different thermal properties—silicon and sapphire, are used to demonstrate that substrates with lower thermal conductivity trap heat flow, inducing larger undercooling, both experimentally and theoretically via finite element simulations. The increased undercooling facilitates the formation of Q-carbon. The Q-carbon is used as nucleation seeds for diamond growth via laser remelting and hot-filament chemical vapor deposition.

The development of advanced fuel fabrication technologies is important for developing accident-tolerant fuels and engineering fuels for safer and more effective nuclear energy systems. In this work, commercial-size uranium dioxide (UO2) fuel pellets with a theoretical density of 95% were consolidated by spark plasma sintering (SPS) at 1600°C for 5 min. Systematic investigations suggest uniform densification and stoichiometric UO2 with an ideal fluorite structure across the commercial-size fuel pellet, but with a distributed grain structure because of non-uniform distribution of temperature during sintering. This work demonstrates a great potential of using SPS for fabricating nuclear fuels at a cost-effective manner.

Low-cost, earth-abundant magnetocaloric materials (MCMs) are required for energy-efficient, green, and affordable magnetic cooling technology. We investigated the magnetic and magnetocaloric properties of rare-earth-free Fe75−xCrxAl25 (19≤x≤25) arc-melted alloys. The Curie temperature (Tc) of these alloys could be tuned from 220 K up to room temperature by Cr additions. The relative cooling power/US$ was found to be superior to other promising MCMs. Fe50Cr25Al25 ball-milled powders, with an average particle size of ~25 nm, were used to prepare magnetic fluid. Maximum cooling (ΔT) of 5.4°C was observed for Fe50Cr25Al25-based fluids.

Amine-based plasma polymer thin films (NH2-PPTFs) are favorable due to their potential ability for binding a variety of biomolecules, especially in biotechnologic studies. In this context, to understand the effect of different amine sources on quartz tuning forks’ (QTF) surface functionalization and isolation, we prepared PPTFs by single-step plasma polymerization process. The amino-group concentration of PPTF's was proportionally increased by increasing discharge powers, whereas not affected from exposure time. It was observed that the resistivity increased with the increasing molecular weight of the precursor. In conclusion, NH2-PPTF-modified QTFs present as a great candidate for future biotechnologic applications.

A computational model for the evaluation of the thermomechanical effects that give rise to the catastrophic optical damage of laser diodes has been devised. The model traces the progressive deterioration of the device running in continuous wave conditions. The local heating of the active layer locally leads to the onset of the plastic regime. As a result, dislocations and threads of dislocations grow across the active layers and lead to rapidly growing temperatures in the quantum well. The poor power dissipation under these conditions has been identified as the key factor driving the final degradation of the laser.

A thermoresponsive large-area plasmonic architecture, made from randomly distributed gold nanoparticles (GNPs) located at the substrate interface of a cholesteric liquid crystal (CLC) cell, is fabricated and thoroughly characterized. A photo-thermal heating effect due to the localized plasmonic resonance (LPR) mechanism is generated by pumping the GNP array with a resonant light beam. The photo-induced heat, propagating through the CLC layer, induces a gradual phase transition from the cholesteric to isotropic phase. Both the plasmonic and photonic properties of the system as both the selective reflection properties and frequency of the LPR are modulated.

Gold nanoparticles (GNPs) of ~8 nm in diameter were used for the detection of organochlorine endosulfan pesticide (ESP) as colorimetric sensor and the design of GNP-based chemical sensor for its quantitative estimation has also been proposed. The original wine red color of GNPs changes into various shades of blue after the addition of different concentrations of ESP solutions. A GNP-based sensing electrode has been used for designing of ESP detection chemical sensor at ambient temperature. The response and sensitivity of ESP sensor parameters are obtained from their recovery curves of the change in resistance versus time.

Akin to the natural tissues, soft artificial muscles possess a life cycle limited by aging and degradation phenomena. Here, we propose a rejuvenation method aimed at silicone-ethanol soft composite actuators, in which ethanol escape occurs during prolonged actuation, thus compromising their performance. The rejuvenation is achieved by immersion of the material–actuator in ethanol, allowing its diffusion into the silicone-based material until saturation. Repeatable rejuvenation of a soft robot, based on the soft material–actuator, resulted in retention of up to 100% of its functionality. Thus, we suggest that this method may be used for the rejuvenation of soft artificial muscles and material–actuators.

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.

Due to the lack of an effective and noninvasive screening tool, the early diagnosis of colorectal cancer (CRC) is currently difficult. For the early diagnosis of CRC, we have developed Fe3O4-Dye800-single chain fragment variable (ScFv)egfr/vegfr nanoprobes. ScFvegfr/vegfr (ScFv2) conjugated onto Fe3O4 nanoprobes efficiently recognized CRC tumors in vitro and in vivo. Near-infrared fluorescence imaging modalities such as Dye800 were utilized simultaneously with magnetic resonance to enhance detection efficiency. Fe3O4-Dye800-ScFv2 successfully detected tiny CRC tumors; the synergistic ScFv2 successfully enhanced CRC targeting. Thus, Fe3O4-Dye800-ScFv2 nanoprobes may represent a new molecular imaging strategy for the early detection of CRC.

Phase-change materials (PCMs) have important applications in optical and electronic storage devices. Ge2Sb2Te5 (GST) is a prototypical phase-change material (PCM) employed in state-of-the-art storage-class memories. In this work, we investigate crystallization of GST at temperatures 600–800 K by ab initio molecular dynamics. We consider large models containing 900 atoms, which enable us to investigate finite-size effects by comparison with smaller models. We use the metadynamics method to accelerate the formation of a large nucleus and then study the growth of the nucleus by unbiased simulations. The calculated crystal growth speed and its temperature-dependent behavior are in line with recent experimental work.

Cation doping is a practical way of engineering the optical properties of one-dimensional semiconductor nanomaterials, such as their band gap. We have grown zinc oxide (ZnO) nanorods doped with sodium cations (Na+) using a hydrothermal method at temperatures as low as 60 °C. We have investigated the effect of different concentrations of Na+ on structural and optical properties and morphology of the ZnO nanostructures. We have also simulated and discussed the chemical route of formation of doped and undoped ZnO nanorods. We found that, for low-temperature hydrothermal doping of ZnO nanorods with Na+, the optimum concentration ratio of zinc to sodium precursors is 1:10.

We synthesized two types of ZnO nanoparticles (NPs) for comparison, the first NPs were produced using a Zn(Ac)2.2H2O solution in distilled water and the second were produced using a Zn(Ac)2.2H2O solution in an aqueous extract of Mentha (mint). The x-ray diffraction patterns were indexed on the basis of a hexagonal (wurtzite) structure. The samples illustrate the high crystalline quality, and the average crystal sizes of the NPs were calculated to be 50 and 60 nm for GS and NS, respectively. ZnO nanorods were produced for the first time by using green synthesis method.

Magnetic tunnel junction can produce highly configurable molecular spintronics devices. This paper highlights a rather subtle attribute of magnetic tunnel junction fabrication that can lead to the very pronounced impact on magnetic properties of molecular spintronics device. We conducted magnetic studies to observe the effect of depositing ~5 nm Tantalum (Ta) on the top of a magnetic tunnel junction. We investigated the effect of Ta by using characterization techniques like ferromagnetic resonance, magnetometry, and polarized neutron reflectometry. Bridging paramagnetic molecules between the two ferromagnetic electrodes of magnetic tunnel junctions with and without Ta top layer produced the very different magnetic response.