Nitric oxide (NO) acts a pivotal role in regulating various physiological processes of vasodilation, platelet aggregation, and vascular smooth muscle cell mitogenesis and proliferation. This makes NO a promising candidate for the treatment of cardiovascular problems like hypertension and vascular stenosis. However, the high reactivity of NO poses an issue for effective NO delivery. To overcome this limitation, recent developments on three-dimensional (3D) materials have been explored with either physical or chemical incorporation of NO releasing donors, to provide spatiotemporal control over NO-signaling pathways in blood vessels. Here, we offer an overview on the current efforts, and propose future perspectives for precise regulation on NO delivery in advanced 3D materials toward proper vascular functionality.

Significant developments in micro-electrical-mechanical systems-based devices for use in transmission electron microscopy (TEM) sample holders have recently led to the commercialization of windowed gas cells that now enable the atomic-resolution visualization of phenomena occurring during gas–solid interactions at atmospheric pressure. In situ TEM study under atmospheric pressures provides unique information that is beneficial to correlating the structure–properties relationship of nanomaterials, particularly under real gaseous environments. We here provide a brief introduction of the advanced instrumentation of windowed gas cells and review recent progress of in situ atomic-resolution TEM study under atmospheric pressures, including some application examples of oxidation and reduction processes, dynamic growth of nanomaterials, catalytic reactions, and “operando” TEM.

Melanin (from the Greek μέλας, mélas, black) is a biopigment ubiquitous in flora and fauna, featuring broadband optical absorption, hydration-dependent electrical response, ion-binding affinity as well as antioxidative and radical-scavenging properties. In the human body, photoprotection in the skin and ion flux regulation in the brain are some biofunctional roles played by melanin. Here we discuss the progress in melanin research that underpins emerging technologies in energy storage/conversion, ion separation/water treatment, sunscreens, and bioelectronics. The melanin research aims at developing approaches to explore natural materials, well beyond melanin, which might serve as a prototype benign material for sustainable technologies.

Polymer:fullerene nanoparticles (NPs) offer two key advantages over bulk heterojunction (BHJ) films for organic photovoltaics (OPVs), water-processability and potentially superior morphological control. Once an optimal active layer morphology is reached, maintaining this morphology at OPV operating temperatures is key to the lifetime of a device. Here we study the morphology of the PDPP-TNT (poly{3,6-dithiophene-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-naphthalene}):PC71BM ([6,6]-phenyl C71 butyric acid methyl ester) NP system and then compare the thermal stability of NP and BHJ films to the common poly(3-hexylthiophene) (P3HT): phenyl C61 butyric acid methyl ester (PC61BM) system. We find that material Tg plays a key role in the superior thermal stability of the PDPP-TNT:PC71BM system; whereas for the P3HT:PC61BM system, domain structure is critical.

The long-term stability of mechanically exfoliated MoS2 flakes was compared for storage in the air and storage under vacuum. Significant changes in MoS2 flakes were observed for samples stored in the air, whereas similar flakes on samples stored in vacuum underwent no change. Small speckles were observed to appear on the surface of flakes stored in the air, followed by thinning and eventual decomposition of MoS2 flakes. The speckles are suspected to be formed by oxidation of MoS2 in the presence of atmospheric oxygen and water molecules, resulting in the formation of hydrated MoO3.

Sodium-ion batteries (SIBs) have received intensive attentions owing to the abundant and inexpensive sodium (Na) resource. Layered vanadium oxides are featured with various valence states and corresponding compounds, and through multi-electron reaction they are capable to deliver high Na storage capacity. The rational construction of unique structures is verified to improve their Na storage properties. This perspective provides an overview of recent advances in layered vanadium oxide for SIBs, with a particular focus on construction of novel nanostructures, and mechanism studies via in situ characterization. Finally, we predict possible breakthroughs and future trends that lie ahead for high-performance layered vanadium oxides SIBs cathode.

In this study, we investigate spray pyrolysis as an approach to synthesis of tunnel structure sodium manganese oxide, as it is a cost-effective and scalable technology. The powders synthesized with Na/Mn ratio of 0.50 displayed a pure tunnel structure, and demonstrated the best electrochemical performance, with a discharge capacity of 115 mAh/g. The material also showed good cycleability and rate capability. Noticeable decay in performance was seen in materials with Na/Mn ratios other than 0.50, indicating that this material is sensitive to minor compositional deviations. This study has demonstrated that spray pyrolysis is a promising synthesis method for this material.

Three-dimensional (3D) scaffolds composed of poly(ε-caprolactone) and gelatin nanofibers were fabricated by a combination of electrospinning and modified gas-foaming. Arrayed holes throughout the scaffold were created using a punch under cryo conditions. The crosslinking with glutaraldehyde vapor improved the water stability of the scaffolds. Cell spheroids of green fluorescent protein-labeled human dermal fibroblasts were prepared and seeded into the holes. It was found that the fibroblasts adhered well on the surface of nanofibers and migrated into the scaffolds due to the porous structures. The 3D nanofiber scaffolds may hold great potential for engineering tissue constructs for various applications.

Phase predictions and characterizations on as-solidified septenary refractory high-entropy alloy, CrMoNbReTaVW, are presented. The simulated solidification process predicts a single body-centered-cubic (BCC) crystal structure with the tendency of compositional segregation. X-ray diffraction results confirm the “single-phase-like” BCC structure, while further experimental characterizations reveal the existence of multiple grains with significantly different compositions yet the same crystal structure and similar lattice parameters.

Partially reduced graphene oxide functionalized with Fe nanoparticles alone or combined with Au and Pt nanoparticles is synthesized and characterized, and their effects on Polymer Electrolyte Membrane Fuel Cell (PEMFC) power output and carbon monoxide resistance are tested. Samples were prepared with various combinations of metal nanoparticles to create a cost-effective catalyst. Transmission and scanning electron microscopy revealed metal nanoparticles embedded on graphene sheets, some with magnetic susceptibility. PEMFC tests exhibited power output that was >180% of the control in a pure H2 gas feed and 250% of the control in a H2 gas feed with 1000 ppm of CO.

Four different vanadium oxide phases [α-vanadium pentoxide (V2O5), β-V2O5, bronze-type vanadium dioxide [VO2(B)], and rutile-type VO2 [VO2(R)])] are investigated from first principles as potential electrode materials for potassium (K) ion batteries. Specifically, insertion energetics and diffusion barriers are computed. These phases are known as promising cathode materials for other types of metal ion batteries. Our results show that the metastable β-V2O5 provides the lowest (strongest) insertion energies for K and the lowest diffusion barriers compared with orthorhombic α-V2O5, VO2(B), and VO2(R). While three of these phases show energetically favorable potassiation and relatively small diffusion barriers, VO2(R) is predicted to be incapable of electrochemical K incorporation.

Mesenchymal stem cell behavior can be regulated through mechanical signaling, either by dynamic loading or through biomaterial properties. We developed intrinsically responsive tissue engineering scaffolds that can dynamically load cells. Porous collagen- and alginate-based scaffolds were functionalized with iron oxide to produce magnetically active scaffolds. Reversible deformations in response to magnetic stimulation of up to 50% were recorded by tuning the material properties. Cells could attach to these scaffolds and magnetically induced compressive deformation did not adversely affect viability or cause cell release. This platform should have broad application in the mechanical stimulation of cells for tissue engineering applications.

We discuss relationships between transparent supercapacitor performance and the morphology of its ZnO nanostructured electrodes. The electrodes with different morphologies were prepared by magnetron sputtering and postdeposition annealing. They were decorated with MnO2 nanostructures and tested in symmetric transparent supercapacitors. The capacitances for discharging at 10 µA/cm2 were in the range of 20–53 µF/cm2, meaning that an increase of 250% in capacitance can be obtained by optimizing the electrode morphology. Optimal morphologies were hierarchical with a large range of pore sizes available. The worst performing had the smallest range of pore sizes. Best devices exhibited transparencies above 90%.

Chemical vapor deposition is the most proficient method for growing graphene on copper foils due to its scalability, repeatability, and uniformity, etc. Herein, we systematically study the effect of oxygen (O2) exposure on graphene growth. We introduced O2 before and during the growth, and then studied its effects on the morphology, crystallinity, and nucleation density of graphene. We observe that introducing O2 during growth significantly improves the graphene crystallinity while pre-dosing O2 before growth reduces the graphene nucleation density. These studies suggest that intermittent O2 exposure play a significant role in graphene growth, enabling scalable production of high-quality graphene.

TiC/H13 nanocomposite parts were processed by selective laser melting using various energy densities; one part also underwent hot isostatic pressing (HIP). The effect of energy density and HIPing on densification, microstructure, and hardness were evaluated. It was found that the densification was not largely affected by the energy density, but the HIP-treated sample displayed a large improvement in relative density. With increasing energy density, the microstructures showed high levels of dispersion of nanoparticles, while HIP treatment coarsened the microstructure and induced agglomeration. Both HIP treatment and increased energy density lowered hardness markedly; this was likely due to annealing effects.

Conjugated polymers have been proposed as promising materials for scaffolds in tissue engineering applications. However, the restricted processability and biodegradability of conjugated polymers limit their use for biomedical applications. Here we synthesized a block-co-polymer of aniline tetramer and PCL (AT–PCL), and processed it into fibrous non-woven scaffolds by electrospinning. We showed that fibronectin (Fn) adhesion was dependent on the AT–PCL oxidative state, with a reduced Fn unfolding length on doped membranes. Furthermore, we demonstrated the cytocompatibility and potential of these membranes to support the growth and osteogenic differentiation of MC3T3-E1 cells over 21 days.

In this work, we investigated the interactions of human mesenchymal stem cells (hMSCs) with three-dimensional (3D) printed scaffolds displaying different scaffold architectures. Pressure-assisted microsyringe system was used to fabricate scaffolds with square (SQR), hexagonal (HEX), and octagonal (OCT) architectures defined by various degrees of curvatures. OCT represents the highest degree of curvature followed by HEX, and SQR is composed of linear struts without curvature. Scaffolds were fabricated from poly(L-lactic acid) and poly(tyrosol carbonate). We found that hMSCs attached and spread by taking the shape of the individual struts, exhibiting high aspect ratios (ARs) and mean cell area when cultured on OCT scaffolds as compared with those cultured on HEX and SQR scaffolds. In contrast, cells appeared bulkier with low AR on SQR scaffolds. These significant changes in cell morphology directly correlate with the stem cell lineage commitment, such that 80 ± 1% of the hMSCs grown on OCT scaffolds differentiated into osteogenic lineage, compared with 70 ± 4% and 62 ± 2% of those grown on HEX and SQR scaffolds, respectively. Cells on OCT scaffolds also showed 2.5 times more alkaline phosphatase activity compared with cells on SQR scaffolds. This study demonstrates the importance of scaffold design to direct stem cell differentiation, and aids in the development of novel 3D scaffolds for bone regeneration.

A hydrothermal method was developed to synthesize Ag–Pt nanoparticles with controlled surface composition where formaldehyde (HCHO) was utilized as a directing agent. Transmission electron microscopy and powder x-ray diffraction characterizations showed no change in bulk composition and phases as well as the size and morphology of as-made bimetallic nanocrystals. X-ray photoelectron spectroscopy study revealed, however, the enrichment of Pt on the surface as the amount of HCHO used increased. This chemically driven change in surface composition represents a nontraditional approach in the control of synthesis of bimetallic nanoparticle catalysts. A close relationship between catalytic performance and surface composition of these Ag–Pt nanocrystals was observed for electrochemical oxidation of formic acid.

We investigate how the local glass-transition temperature (T g) depends on film thickness in monolayer and bilayer thin films with a polystyrene (PS) upper-layer and a poly(methyl methacrylate) (PMMA) lower-layer using coarse-grained simulations. Interactions between overlapping interphases demonstrate a superposition principle for describing their glass-transition behaviors. For supported bilayer films, the free surface effect on a PS film upper-layer is effectively eliminated due to an enhanced local T g near the PS–PMMA interface, which cancels out depressed T g near the free surface. However, at very low PMMA lower-layer thicknesses, the PMMA-substrate effect can penetrate through the polymer–polymer interface, leading to enhanced T g in the PS upper-layer.

The novel Three-dimensional rambutan-like NiCo2O4 microspheres have been successfully coated onto surface of carbon nanofibers (CNFs) to form NiCo2O4–CNFs hybrids. The composition and microstructure of NiCo2O4–CNFs were characterized by the field-emission scanning electronmicroscopy, x-ray photoelectron spectroscopy, transmission electron microscopy, and x-ray diffractometer. The obtained NiCo2O4–CNFs exhibited a specific capacity of 160 mAh/g at 1 mA/cm2 in 2 M potassium hydroxide aqueous solution. The specific capacity gradually increases with the increasing of cycles; and after 3000 cycles, the specific capacity still can be remained over 90%.