The Cu precipitation in a quench-aged high-strength low-alloy steel is studied at the atomic scale by atom probe tomography and high-resolution transmission electron microscopy. The results indicate that the Cu precipitates greatly correlate with carbides in the aspect of distributional character, i.e., the two phases are prone to coprecipitate on the dislocations and/or interfaces (low angle boundaries of the martensite laths). The crystallographic defects have a significant effect on the sizes, morphology and composition of Cu precipitates with Ni and Mn segregation shell.

Multiwalled carbon nanotube (MWCNT)-reinforced copper (Cu) nanocomposite coatings were consolidated using kinetic spraying. Nanocomposite particles colliding with supersonic velocity led to severe plastic deformation and deposition and resulted in bimodal structural evolution by grain refinement and work hardening. These microstructural factors contributed to the remarkable strengthening of the nanocomposites in conjunction with Orowan looping of MWCNTs. In this study, the microstructural and physical metallurgical analyses were performed to understand the strengthening mechanisms of MWCNT/Cu nanocomposites consolidated by kinetic spraying.

The covalent attachment of cysteamine-functionalized polyaniline (PANI–NH2) nanofibers onto graphene oxide (GO) sheets in an aqueous medium is investigated for the first time. The functionalized PANI is covalently attached onto the GO surface by simple amidation in the presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide. The technique can be conveniently scaled up for bulk production. The hybrid nanomaterial is easily synthesized, has good thermal stability, and disperses well in a solvent. Characterization techniques (Fourier transform infrared spectroscopy, thermogravimetry analysis, field emission scanning electron microscopy, and transmission electron microscopy) indicate the successful binding of the functionalized PANI nanofibers onto GO.

Papyrus writings from 1600–1500 BC describe cancer and the attempts at treatment. Centuries later, cancer remains a devastating disease. Given the long history of difficulties in developing cancer therapies, why is there excitement about nanoparticle medicine (nanomedicines) for fighting cancer? This article describes the current understanding of why these engineered, nano-sized medicines, which are highly multifunctional chemical systems, have the potential to provide revolutionary ways to treat cancer. This point is illustrated by physical insights at the nanoscale that allow for the development of nanoparticles that can function in both animals and humans. The human data show how we have translated two independent nanoparticle cancer therapeutics from laboratory curiosities to experimental therapeutics in human clinical trials.

Fundamental aspects of the interactions between cells and biomaterials provide a crucial framework for the design of many systems that interact with the human body. A comprehensive understanding of multifactorial processes may provide an adequate basis for the rational design of implantable devices ranging from nanoparticles for drug delivery and scaffolds for tissue engineering, to artificial organs for augmentation and rehabilitation. Recent progress in the elucidation of cell-biomaterials interactions has been predicated on advances in polymer chemistry, materials engineering, and device microfabrication. The confluence of these developments has stimulated a newfound ability to design soft materials and interfaces with precise chemical, physical, and mechanical properties. While static surfaces can yield insight into the interaction of mammalian cells with medical materials, the study of fundamental cell-biomaterials phenomena will benefit significantly from the ability to present biologically active signals to cells with spatiotemporal control. Specifically, the use of dynamic materials and interfaces can mirror the intrinsic dynamic behavior of living cells. This article highlights recent advances in soft materials design, interfacial engineering, and synthetic polymer networks in the context of producing dynamic materials to study cell-biomaterials interactions. Emerging challenges and future research directions are also discussed.

Developing wireless nanodevices and nanosystems is critical for sensing, medical science, environmental/infrastructure monitoring, defense technology, and even personal electronics. It is highly desirable for wireless devices to be self-powered without using a battery. We have developed piezoelectric nanogenerators that can serve as self-sufficient power sources for micro-/nanosystems. For wurtzite structures that have non-central symmetry, such as ZnO, GaN, and InN, a piezoelectric potential (piezopotential) is created by applying a strain. The nanogenerator uses the piezopotential as the driving force, responding to dynamic straining of piezoelectric nanowires. A gentle strain can produce an output voltage of up to 20–40 V from an integrated nanogenerator. Furthermore, piezopotential in the wurtzite structure can serve as a “gate” voltage that can effectively tune/control charge transport across an interface/junction; electronics based on such a mechanism are referred to as piezotronics, with applications such as electronic devices that are triggered or controlled by force or pressure, sensors, logic units, and memory. By using the piezotronic effect, we show that optoelectronic devices fabricated using wurtzite materials can provide superior performance for solar cells, photon detectors, and light-emitting diodes. Piezotronic devices are likely to serve as “mediators” for directly interfacing biomechanical action with silicon-based technology. This article reviews our study of ZnO nanostructures over the last 12 years, with a focus on nanogenerators and piezotronics.