Electron Beam-Induced Reduction of Cuprite

Cu-based materials are used in various industries, such as electronics, power generation, and catalysis. In particular, monolayered cuprous oxide (Cu2O) has potential applications in solar cells owing to its favorable electronic and magnetic properties. Atomically thin Cu2O samples derived from bulk cuprite were characterized by high-resolution transmission electron microscopy (HRTEM). Two voltages, 80 kV and 300 kV, were explored for in situ observations of the samples. The optimum electron beam parameters (300 kV, low-current beam) were used to prevent beam damage. The growth of novel crystal structures, identified as Cu, was observed in the samples exposed to isopropanol (IPA) and high temperatures. It is proposed that the exposure of the copper (I) oxide samples to IPA and temperature causes material nucleation, whereas the consequent exposure via e-beams generated from the electron beam promotes the growth of the nanosized Cu crystals

Prediction of magnesium-based bulk metallic glasses and their microstructural characterization

The development of advanced materials has resulted in the evolution of new class of materials called bulk metallic glasses...This thesis deals with efforts to meet two main challenges currently faced in the development of novel bulk metallic lass systems in genera, and Mg - based bulk metallic glasses in particular. Firstly, the development of a multifunctional optimization model, for selecting new Mg - based bulk metallic glass-forming compositions lighter than Al based on past research spanning over a decade. Secondly, understanding the challenges an artifacts associated with the transmission electron microscopy characterization of Mg₅₄Cu₂₈Ag₇Y₁₁ bulk metallic glasses and developing an artifact-free specimen preparation protocol for their microstructural characterization --Abstract, page iii

Electron Beam-Induced Reduction of Cuprite

Cu-based materials are used in various industries, such as electronics, power generation, and catalysis. In particular, monolayered cuprous oxide (Cu2O) has potential applications in solar cells owing to its favorable electronic and magnetic properties. Atomically thin Cu2O samples derived from bulk cuprite were characterized by high-resolution transmission electron microscopy (HRTEM). Two voltages, 80 kV and 300 kV, were explored for in situ observations of the samples. The optimum electron beam parameters (300 kV, low-current beam) were used to prevent beam damage. The growth of novel crystal structures, identified as Cu, was observed in the samples exposed to isopropanol (IPA) and high temperatures. It is proposed that the exposure of the copper (I) oxide samples to IPA and temperature causes material nucleation, whereas the consequent exposure via e-beams generated from the electron beam promotes the growth of the nanosized Cu crystals

Targeted Imaging and Therapeutic Technologies in Neuroregeneration

Extremity injuries are less likely to be fatal than head, chest, and abdominal wounds; however, they can be severely disabling. Peripheral nerve injury (PNI) can result from trauma (lacerations, penetrating injury, stretching, ischemia or crushing trauma and fractures, and gunshot wounds), repetitive compression (tunnel syndromes), or iatrogenic causes (orthopedic, plastic, neurosurgical or other surgical procedures such as oncologic resection). Nerve regeneration is an essential process needed for the recovery of function. However, our understanding of this process is still rather limited, and access to successful personalized regeneration supportive treatment is lacking. This chapter focuses on surveying new technological advances such as targeted nanoimaging and immunomodulation in support of neuroregeneration following peripheral injuries. Specifically, we highlight new nanotechnology advances in targeted cell tracking and imaging, as well as targeted drug delivery and cellular therapeutics. Though most of this work is preclinical, we hope that these advances drive the development of novel, safe and effective clinical solutions

Electrical Properties of Hybrid Nanomembrane/Nanoparticle Heterojunctions: The Role of Inhomogeneous Arrays

Investigation of charge transport mechanisms across inhomogeneous nanoparticle (NP) layers in heterojunctions is one of the key technological challenges nowadays for developing novel hybrid nanostructured functional elements. Here, we successfully demonstrate for the first time the fabrication and characterization of a novel hybrid organic/inorganic heterojunction, which combines free-standing metallic nanomembranes with self-assembled mono- and sub-bilayers of commercially available colloidal NPs with no more than ∼10⁵ NPs. The low-temperature conductance–voltage spectra exhibit Coulomb features that correlate with various interface’s configurations, including the presence of inhomogeneities at the nano- and micrometer scale owing to the NP size, the micrometer-sized voids, and the thickness of the layers. The charge transport features observed can be explained by a superposition of conductance characteristics of each individual type of NPs. The procedure adopted to fabricate the heterojunctions as well as the theoretical approach employed to study the charge transport mechanisms across the NP layers may be of interest for investigating different types of NPs and commonly obtained inhomogeneous layers. In addition, the combination of metallic nanomembranes with self-assembled layers of NPs makes such a hybrid organic/inorganic heterostructure an interesting platform and building block for future nanoelectronics, especially after intentional tuning of its electronic behavior

Room Temperature in Situ Growth of B/BO_<i>x</i> Nanowires and BO_<i>x</i> Nanotubes

Despite significant advances in the synthesis of nanostructures, our understanding of the growth mechanisms of nanowires and nanotubes grown from catalyst particles remains limited. In this study we demonstrate a straightforward route to grow coaxial amorphous B/BO_<i>x</i> nanowires and BO_<i>x</i> nanotubes using gold catalyst particles inside a transmission electron microscope at room temperature without the need of any specialized or expensive accessories. Exceedingly high growth rates (over 7 μm/min) are found for the coaxial nanowires, and this is attributed to the highly efficient diffusion of B species along the surface of a nanowire by electrostatic repulsion. On the other hand the O species are shown to be relevant to activate the gold catalysts, and this can occur through volatile O species. The technique could be further developed to study the growth of other nanostructures and holds promise for the room temperature growth of nanostructures as a whole