Investigation of airborne nanoparticles emitted during the laser cleaning process of corroded metal surface.

Laser surface cleaning is a promising surface-cleaning technique owing to its numerous benefits, including its noncontact behavior, ease of control, high precision, and no secondary waste generation. However, it cannot prevent airborne nanoparticle emissions during the laser cleaning process. Therefore, the effects of laser-cleaning parameters on airborne nanoparticle generation are analyzed to design potential remediation methods. In this study, the nanoparticles released during the laser cleaning of corroded 304L stainless steel surfaces were investigated. Electrical low-pressure impactor analysis and electron microscopy were conducted to determine how laser parameters influenced the size and amount of emitted nanoparticles. Based on these findings, the feasibility of the filtering emitted nanoparticles using high-efficiency particulate air filters was examined.

Host-Guest Systems on the Surface of Functionalized Superparamagnetic Iron Oxide Nanoparticles (SPIONs) Utilizing Hamilton Receptors and Cyanurate Derivative Molecules.

The study of hydrogen bonding interactions at the level of functionalized nanoparticles remains highly challenging and poorly explored area. In this work, superparamagnetic iron oxide nanoparticles (SPIONs) were orthogonally functionalized using receptors bearing multiple hydrogen bonding motifs. Pristine SPIONs were modified by wet chemical processes with Hamilton receptors (hosts), or cyanurate-guest molecules linked to phosphonic acid moieties for monolayer functionalization. The modified surfaces were fully characterized and the number of attached ligands on the surface were determined. The host-guest interactions on the interface of modified SPIONs were investigated by using UV-Vis spectroscopic titrations. Functionalized SPIONs demonstrated two to three magnitudes stronger binding affinities as compared to the related molecular interactions in solution due to synergistic effects on complex surface environment. Higher supramolecular binding ratios of host-guest interactions on the modified surface were emerged. These studies provide fundamental insights into supramolecular complexations on the surface at solid-liquid interface systems with applications in engineered nanomaterials, nano-sensing devices, and drug delivery systems.

Enhanced In Vitro Biocompatibility and Water Dispersibility of Magnetite and Cobalt Ferrite Nanoparticles Employed as ROS Formation Enhancer in Radiation Cancer Therapy.

Efficient magnetic reactive oxygen species (ROS) formation enhancing agents after X-ray treatment are realized by functionalizing superparamagnetic magnetite (Fe3 O4 ) and Co-ferrite (CoFe2 O4 ) nanoparticles with self-assembled monolayers (SAMs). The Fe3 O4 and CoFe2 O4 nanoparticles are synthesized using Massart's coprecipitation technique. Successful surface modification with the SAM forming compounds 1-methyl-3-(dodecylphosphonic acid) imidazolium bromide, or (2-{2-[2-hydroxy-ethoxy]-ethoxy}-ethyl phosphonic acid provides biocompatibility and long-term stability of the Fe3 O4 and CoFe2 O4 nanoparticles in cell media. The SAM-stabilized ferrite nanoparticles are characterized with dynamic light scattering, X-ray powder diffraction, a superconducting quantum interference device, Fourier transform infrared attenuated total reflectance spectroscopy, zeta potential measurements, and thermogravimetric analysis. The impact of the SAM-stabilized nanoparticles on the viability of the MCF-7 cells and healthy human umbilical vein endothelial cells (HUVECs) is assessed using the neutral red assay. Under X-ray exposure with a single dosage of 1 Gy the intracellular SAM stabilized Fe3 O4 and CoFe2 O4 nanoparticles are observed to increase the level of ROS in MCF-7 breast cancer cells but not in healthy HUVECs. The drastic ROS enhancement is associated with very low dose modifying factors for a survival fraction of 50%. This significant ROS enhancement effect by SAM-stabilized Fe3 O4 and CoFe2 O4 nanoparticles constitutes their excellent applicability in radiation therapy.

Stimulus-Responsive Gas Marbles as an Amphibious Carrier for Gaseous Materials.

Gas marbles are a new family of particle-stabilized soft dispersed system with a soap bubble-like air-in-water-in-air structure. Herein, stimulus-responsive character is successfully introduced to a gas marble system for the first time using polymer particles carrying a poly(tertiary amine methacrylate) (pKa ≈7) steric stabilizer on their surfaces as a particulate stabilizer. The gas marbles exhibited long-term stability when transferred onto the planar surface of liquid water, provided that the solution pH of the subphase is basic and neutral. In contrast, the use of acidic solutions led to immediate disintegration of the gas marbles, resulting in release of the inner gas. The critical minimum solution pH required for long-term gas marble stability correlates closely with the known pKa value for the poly(tertiary amine methacrylate) stabilizer. It also demonstrates amphibious motions of the gas marbles.

A Sustainable Method for Removal of the Full Range of Liquid and Solid Hydrocarbons from Water Including Up- and Recycling.

Beyond their CO2 emittance when burned as fuels, hydrocarbons (HCs) serve as omnipresent raw materials and commodities. No matter if as liquid oil spills or the endless amounts of plastic roaming the oceans, HCs behave as persistent pollutants with water as main carrier to distribute. Even if their general chemical structure [-(CH2 )n -] is quite simple, the endless range of n leads to contaminations of different appearances and properties. A water remediation method based on superparamagnetic iron oxide nanoparticles (SPIONs) modified with self-assembled monolayers of alkyl phosphonic acid derivatives is presented. These molecules enable the SPIONs to non-covalently bind HCs, independently from the molecular weight, size and morphology. The attractive interaction is mainly based on hydrophobic and Coulomb interaction, which allows recycling of the SPIONs. The superparamagnetic core allows a simple magnetic collection and separation from the water phase which makes it a promising addition to wastewater treatment. Agglomerates of collected plastic "waste" even exhibit superior adsorption properties for crude oil, another hydrocarbon waste which gives these collected wastes a second life. This upcycling approach combined with presented recycling methods enables a complete recycling loop.

Fabrication of SiNx-based photonic crystals on GaN-based LED devices with patterned sapphire substrate by nanoimprint lithography.

SiNx-based photonic crystal (PhC) patterns were fabricated on the ITO electrode layer of a GaN-based light-emitting diode (LED) device on a patterned sapphire substrate (PSS) by a UV nanoimprint lithography process in order to improve the light extraction of the device. A three-dimensional finite-difference time-domain simulation confirmed that the light extraction of a GaN LED structure on a PSS is enhanced when SiNx PhC patterns are formed on the ITO top layer. From the I-V characteristics, the electrical properties of patterned LED devices with SiNx-based PhC were not degraded compared to the unpatterned LED device, since plasma etching of the p-GaN or the ITO layers was not involved in the patterning process. Additionally, the patterned LED devices with SiNx-based PhCs showed 19%-increased electroluminescence intensity compared with the unpatterned LED device at 445 nm wavelength when a 20 mA current is driven.

The fabrication of a patterned ZnO nanorod array for high brightness LEDs.

In this study, a patterned ZnO nanorod array was formed on the ITO layer of GaN-based light-emitting diodes (LEDs), to increase the light extraction efficiency of the LED. The bi-layer imprinted resin pattern was used for selective growth of the ZnO nanorod array on the ITO layer. Compared to conventional LEDs grown on patterned sapphire substrate (PSS), the deposition of the blanket ZnO layer on the ITO layer increased the light extraction efficiency of the LED by about 10%. Further growth of the ZnO nanorod layer on the blanket ZnO layer increased the light extraction efficiency of the LED by about 23%. In the case that a patterned ZnO nanorod layer was formed on a blanket ZnO layer, the light extraction efficiency increased by about 34%. These enhancements of the device were caused by modulation of the refractive-index in ZnO layers and the surface roughening effects because of the unique design of the pattern, which was nanostructure-in-nanopattern, resulting in the formation of many escape cones on the LED surface.

Transition Metal-Oxide Free Perovskite Solar Cells Enabled by a New Organic Charge Transport Layer.

Various electron and hole transport layers have been used to develop high-efficiency perovskite solar cells. To achieve low-temperature solution processing of perovskite solar cells, organic n-type materials are employed to replace the metal oxide electron transport layer (ETL). Although PCBM (phenyl-C61-butyric acid methyl ester) has been widely used for this application, its morphological instability in films (i.e., aggregation) is detrimental. Herein, we demonstrate the synthesis of a new fullerene derivative (isobenzofulvene-C60-epoxide, IBF-Ep) that serves as an electron transporting material for methylammonium mixed lead halide-based perovskite (CH3NH3PbI(3-x)Cl(x)) solar cells, both in the normal and inverted device configurations. We demonstrate that IBF-Ep has superior morphological stability compared to the conventional acceptor, PCBM. IBF-Ep provides higher photovoltaic device performance as compared to PCBM (6.9% vs 2.5% in the normal and 9.0% vs 5.3% in the inverted device configuration). Moreover, IBF-Ep devices show superior tolerance to high humidity (90%) in air. By reaching power conversion efficiencies up to 9.0% for the inverted devices with IBF-Ep as the ETL, we demonstrate the potential of this new material as an alternative to metal oxides for perovskite solar cells processed in air.

Improvement of photon extraction efficiency of GaN-based LED using micro and nano complex polymer structures.

A micro- and nanoscale complex structure made of a high refractive index polymer (n = 2.08) was formed on the ITO electrode layer of an edge-emitting type GaN blue light-emitting diode (LED), in order to improve the photon extraction efficiency by suppressing total internal reflection of photons. The nanoimprint lithography process was used to form the micro- and nanoscale complex structures, using a polymer resin with dispersed TiO2 nano-particles as an imprint resin. Plasma processing, such as reactive ion etching, was used to form the micro- and nano-scale complex structure; thus, plasma-induced damage to the LED device can be avoided. Due to the high refractive index polymeric micro- and nanostructure on the ITO layer, the electroluminescence emission was increased up to 20%, compared to an identical LED that was grown on a patterned sapphire substrate to improve photon extraction efficiency.