Novel mixed micelle was successfully fabricated by the synergistic self-assembly of poly(methacrylate isobutyl polyhedral oligomeric silsesquioxane (POSS)-co-N-isopropylacrylamide-co-oligo(ethylene glycol)methyl ether methacrylate-co-acrylic acid) (P(methacrylate isobutyl (MAPOSS)-co-NIPAM-co-OEGMA-co-AA)) and poly(methacrylate isobutyl POSS-co-N-isopropylacrylamide-co-oligo(ethylene glycol) methyl ether methacrylate-co-2-vinylpyridine) (P(MAPOSS-co-NIPAM-co-OEGMA-co-2VP)). Dynamic light scattering (DLS) and transmission electron microscopy characterizations demonstrate that the formation of mixed micelles is driven by electrostatic interaction. The formation of the mixed micelles was further implied by a simple fluorescence resonance energy transfer based technique. The mixed micelle possesses the biggest size at pH = 7.0, which is attributed to the strongest electrostatic interaction between the two kinds of micelles. The zeta potential under different pH was detected to further investigate the surface charges corroborating the discussions. DLS and UV-vis indicate that the lower critical solution temperature (LCST) is pH dependent. The mixed micelles reach the highest LCST at pH 7.0. The LCST of the mixed micelle can be tuned by adjusting the volume ratio of the two kinds of micelles as well. Moreover, the thermo-responsive behavior of the mixed micelle is absolutely reversible.

The 1 nm tin oxides–tin (SnOx –Sn) compound films were thermally evaporated onto the chemical vapor deposition (CVD)-grown graphene films for the improved nitrogen dioxide (NO2) gas sensitivity, and the effects of the fabrication temperature and oxygen (O2) flux on the properties of the SnOx –Sn/graphene hybrid sensors including their composition, morphology, and microstructure as well as NO2 sensitivity were investigated. The composition of the SnOx –Sn compound films exhibited strong dependence on the fabrication temperature and O2 flux which could be ascribed to the hybrid effect of the desorption of the oxygen functional groups on the graphene and oxidation of the graphene and Sn. Such combining effects also demonstrated tremendous influence on the SnOx –Sn film morphology, in which the enhanced desorption of the oxygen functional groups on the graphene together with the oxidation of Sn with increasing fabrication temperature would facilitate the formation of large grain-sized and discontinuous films while the increasing O2 flux showed the opposite effects. Meanwhile, the crystallization of the SnOx –Sn compound films was promoted and deteriorated with the increasing temperature and O2 flux, respectively. The SnOx –Sn film morphology played vital role in NO2 gas sensitivity at room temperature, and the mechanism responsible for that was also discussed.

The effect of boron on the room-temperature dynamic properties of Ti-6Al-4V alloy with and without boron addition in as-cast and β-forged conditions is studied by varying number of loading cycles, frequency of loading, and strain amplitude. Boron addition seems to lower the complex modulus and increases the damping of the base Ti-6Al-4V alloy. TiB precipitates in boron modified alloys play a key role in improving the damping through dislocation pinning (at all frequencies) and grain boundary pinning (at high frequencies). These effects are more prominent after β-forging wherein arrangement of TiB particles is found to be a deciding factor. Strain amplitude variation of damping shows trend reversal between 10 and 87 Hz frequencies; damping increases with strain amplitude at 10 Hz but reduces with strain amplitude at 87 Hz. A damping peak occurs near the 50 Hz frequency, and cycling through this range results in a significant improvement in damping (21% for as-cast and 93% for β-forged alloys).

Three-dimensional (3D) tomography using electrons and x-rays has pushed and expanded our understanding of the micro- and nanoscale spatial organization of inorganic, organic, and biological materials. While a significant impact on the field of materials science has already been realized from tomography applications, new advanced methods are quickly expanding the versatility of this approach to better link structure, composition, and function of complex 3D assemblies across multiple scales. In this article, we highlight several frontiers where new developments in tomography are empowering new science across biology, chemistry, and physics. The five articles that appear in this issue of MRS Bulletin describe some of these latest developments in detail, including analytical electron tomography, atomic resolution electron tomography, advanced recording schemes in scanning transmission electron microscopy (STEM) tomography, cryo-STEM tomography of whole cells, and multiscale correlative tomography.

Three-dimensional (3D) scanning transmission electron microscopy (STEM) has become one of the primary tools for analytical characterization in materials science and also finds increasing use in the life sciences. A number of different recording schemes exist for the acquisition of 3D data using STEM, each capturing different spatial frequencies and, thus, different information about the shape of a specimen. In this article, we present and compare different sampling approaches based on images with both large and small depth of field. We highlight the latest contribution to 3D data acquisition, the combined tilt, and focal series. This recording scheme combines the advantages of tilt series-based tomography with 3D data acquisition using a focal series and is particularly beneficial for imaging specimens with a thickness of 1 µm or greater.

Visible-light responsive plasmonic Ag2O/Ag/g-C3N4 nanosheets (NS) were successfully prepared by a simple and green photodeposition method. The obtained composites were characterized by XRD, Fourier transform infrared, transmission electron microscopy, UV-vis, and the photoluminescence (PL) results indicated that the Ag2O/Ag/g-C3N4 NS composites showed better photoabsorption performance than g-C3N4 due to the surface plasmon resonance effect of Ag nanoparticles. Meanwhile, the composite exhibited excellent photocatalytic activities, which was ∼3.8 and ∼3.0 times higher than those of bulk g-C3N4 and pure g-C3N4 NS, respectively. Moreover, the as-prepared composites showed a high structural stability in the photodegradation of Rhodamine B. A possible photocatalytic and charge separation mechanism was suggested based on the PL spectra and the active species trapping experiment.

Over the last two decades, three-dimensional (3D) imaging by transmission electron microscopy or “electron tomography” has evolved into a powerful tool to investigate a variety of nanomaterials in different fields, such as life sciences, chemistry, solid-state physics, and materials science. Most of these results were obtained with nanometer-scale resolution, but different approaches have recently pushed the resolution to the atomic level. Such information is a prerequisite to understand the specific relationship between the atomic structure and the physicochemical properties of (nano)materials. We provide an overview of the latest progress in the field of atomic-resolution electron tomography. Different imaging and reconstruction approaches are presented, and state-of-the-art results are discussed. This article demonstrates the power and importance of electron tomography with atomic-scale resolution.

Thermogelling polymers belong to a class of stimuli-responsive hydrogels that undergo a macroscopic sol-to-gel transition in response to temperature. Much of the ongoing research in this field is focused on hydrogels for biomedical applications as an injectable sustained drug-release matrix or scaffolds for tissue regeneration. Despite robust developments in biodegradable thermogelling polymers in recent decades, the field still faces challenges in the optimization of materials properties. Thorough investigation must be performed to understand the effectiveness of drug delivery using hydrogel-forming polymer carriers. A highlighted case study on OncoGel, an experimental drug delivery depot formulation, sheds some light on the shortcomings of biodegradable thermogelling polymers as drug delivery systems. In this article, we highlight developments in biodegradable thermoresponsive polymers for biomedical applications over the past three years, with a focus on materials/technical challenges and the approaches used to resolve these problems.

This article highlights recent advances in analytical electron tomography (AET), the three-dimensional (3D) extension of conventional nanoanalytical techniques, in which electron energy loss, x-ray spectroscopy, and electron diffraction are combined with tomographic acquisition and reconstruction. Examples from the literature illustrate how new 3D information, gleaned from AET, provides insights into not just morphology and composition, but also the electronic, chemical, and optical properties of materials at the nanoscale. We describe how the “multidimensional” nature of AET leads to “big data” sets, how these can be analyzed optimally, and how AET may develop further.