Surfactant‐Free Sub‐2 nm Ultrathin Triangular Gold Nanoframes

Ultrathin triangular gold nanoframes are synthesized in high yield through selective gold deposition on the edges of triangular silver nanoprisms and subsequent silver etching with mild wet etchants. These ultrathin gold nanoframes are surfactant‐free with tailorable ridge thickness from 1.8 to 6 nm and exhibit adjustable and distinct surface plasmon resonance bands in the visible and near‐IR region. In comparison, etching of the nanoprism template by galvanic replacement can only create frame structures with much thicker ridges, which have much lower catalytic activity for 4‐nitrophenol reduction than the ultrathin gold nanoframes.     

Intermetallic phase transformations in Au–Al wire bonds

This paper describes the crystallochemical mechanisms that underpin the migration of nano-size alumina, intermetallic growth and phase transformations in Au–Al wire bonds during annealing from 175 °C to 250 °C by utilizing high-resolution transmission electron microscopy (HRTEM). Alumina, encapsulated within the Au–Al intermetallic compounds (IMCs), migrates towards the Au ball during annealing, with Au diffusion into the Al pad. The sequence of Au–Al IMC phase development during annealing was investigated. Initially, Au₈Al₃ appears as a third phase between the Au₄Al and AuAl₂ layers that form during bonding, and gradually becomes the dominant compound. Both AuAl₂ and Au₈Al₃ are transformed into the Au-rich alloyAu₄Al when Al is completely consumed, and this is the terminal product.     

Long-Lived Liquid Marbles for Green Applications

Liquid marbles allow for quantities of various liquids to be encapsulated by hydrophobic particles, thus ensuring isolation from the external environment. The unique properties provided by this soft solid has allowed for use in a wide array of different applications. Liquid marbles do however have certain drawbacks, with lifetime and robustness often being limited. Within this review, particle characteristics that impact liquid marble stability are critically discussed, in addition to other factors, such as internal and external environments, that can be engineered to achieve a robust long-lived liquid marble. New emerging applications, which will benefit from this improvement, are explored such as unconventional computing, cell mimicry, and soft lithography. Incorporation of liquid marbles and liquid crystal technologies shows promise in utilizing structural color for optical display applications, and within green and environmental applications, liquid marble technology is increasingly adapted for use in energy conversion, heavy metal recovery, CO₂ capture, and oil removal.     

Using chondroitin sulfate to improve the viability and biosynthesis of chondrocytes encapsulated in interpenetrating network (IPN) hydrogels of agarose and poly(ethylene glycol) diacrylate

We recently introduced agarose-poly(ethylene glycol) diacrylate (PEGDA) interpenetrating network (IPN) hydrogels to cartilage tissue engineering that were able to encapsulate viable cells and provide a significant improvement in mechanical performance relative to its two constituent hydrogels. The goal of the current study was to develop a novel synthesis protocol to incorporate methacrylated chondroitin sulfate (MCS) into the IPN design hypothesized to improve cell viability and biosynthesis. The IPN was formed by encapsulating porcine chondrocytes in agarose, soaking the construct in a solution of 1:10 MCS:PEGDA, which was then photopolymerized to form a copolymer network as the second network. The IPN with incorporated CS (CS-IPN) (~0.5 wt%) resulted in a 4- to 5-fold increase in the compressive elastic modulus relative to either the PEGDA or agarose gels. After 6 weeks of in vitro culture, more than 50% of the encapsulated chondrocytes remained viable within the CS-modified IPN, in contrast to 35% viability observed in the unmodified. At week 6, the CS-IPN had significantly higher normalized GAG contents (347 ± 34 μg/μg) than unmodified IPNs (158 ± 27 μg/μg, P < 0.05). Overall, the approach of incorporating biopolymers such as CS from native tissue may provide favorable micro-environment and beneficial signals to cells to enhance their overall performance in IPNs.     

Effect of synthesis conditions on properties of poly(N-isopropylacrylamide) gels

Properties of poly(N-isopropylacrylamide) gels—equilibrium degree of swelling, shear modulus, effective crosslink density and clarity—depend significantly upon the conditions of synthesis. While it is well known that monomer and crosslinker concentrations affect gel properties, other variables are shown here to have significant effects on the properties of the resulting gels. Initiator type and concentration, synthesis temperature, mold geometry and polymerization time all significantly affect the properties, including the swelling degree. Evidence suggests that the microstructure of these gels is particularly sensitive to these variables.     

Novel Zn-Sn-O nanocactus with excellent transport properties as photoanode material for high performance dye-sensitized solar cells

A novel chemically stable Zn-Sn-O nanocactus structure has been synthesized for the first time using a hydrothermal method. The Zn-Sn-O nanocactus structure comprises a Zn poor-Zn(2)SnO(4) plate and Zn-doped SnO(2) nanothorns growing on the plate, both of which have high electron mobilities. The nanocactus is used as the photoanode of dye-sensitized solar cells (DSSCs). The overall power conversion efficiency (PCE) for the Zn-Sn-O nanocactus film reaches 2.21%, which is twice the previous reported efficiency of pure SnO(2). Electrochemical impedance spectroscopy (EIS) measurements show that the Zn-Sn-O nanocactus film has a good effective diffusion length and high intrinsic electron mobility. After TiCl(4) treatment of the Zn-Sn-O nanocactus film, the current density increases nearly three times and the PCE increases to 6.62%, which compares favourably with the P25 DSSCs (6.97%) and is much higher than that of the SnO(2) (1.04%) or Zn(2)SnO(4) (3.7%)-based DSSCs.     

Liquid Marbles in Liquid

Traditional liquid marbles (LMs), liquid droplets encapsulated by hydrophobic particles at the liquid–gas interface, are restricted by their short lifetime and low heat transfer efficiency. Herein, a new paradigm for LMs immersed in various liquid mediums with massive enhanced heat transfer and spatial recognition is designed; without compromising the structural integrity, the lifetime of the liquid marbles in liquid (LMIL) is extended by ≈1000 times compared to classical LMs in air or naked droplets in organic reagents. The LMIL shows promising reverse structural re‐configurability while under external stimuli and maintaining their functionality for a very long period of time (≈weeks). These superior behaviors are further exploited as a miniature reactor with prolonged lifetimes and excellent temperature control, combined with its feasible operation, new opportunities will open up in the advanced chemical and biomedical engineering fields. It is also shown that LMIL can be applied in methylene blue degradation and 3D in‐vitro yeast cell cultures. These findings have important implications for real‐world use of LMs, with a number of applications in cell culture technology, lab‐in‐a‐drop, polymerization, encapsulation, formulation, and drug delivery.