Strong, Conductive, Lightweight, Neat Graphene Aerogel Fibers with Aligned Pores

Liquid crystals of anisotropic colloids are of great significance in the preparation of their ordered macroscopic materials, for example, in the cases of carbon nanotubes and graphene. Here, we report a facile and scalable spinning process to prepare neat “core–shell” structured graphene aerogel fibers and three-dimensional cylinders with aligned pores from the flowing liquid crystalline graphene oxide (GO) gels. The uniform alignment of graphene sheets, inheriting the lamellar orders from GO liquid crystals, offers the porous fibers high specific tensile strength (188 kN m kg^–1) and the porous cylinders high compression modulus (3.3 MPa). The porous graphene fibers have high specific surface area up to 884 m² g^–1 due to their interconnected pores and exhibit fine electrical conductivity (2.6 × 10³ to 4.9 × 10³ S m^–1) in the wide temperature range of 5–300 K. The decreasing conductivity with decreasing temperature illustrates a typical semiconducting behavior, and the 3D interconnected network of 2D graphene sheets determines a dual 2D and 3D hopping conduction mechanism. The strong mechanical strength, high porosity, and fine electrical conductivity enable this novel material of ordered graphene aerogels to be greatly useful in versatile catalysts, supercapacitors, flexible batteries and cells, lightweight conductive fibers, and functional textiles

Re-Seeing Composition: Object Oriented Reflective Teaching Practice

abstract: This dissertation presents reflective teaching practices that draw from an object-oriented rhetorical framework. In it, practices are offered that prompt teachers and students to account for the interdependent relationships between objects and writers. These practices aid in re-envisioning writing as materially situated and leads to more thoughtful collaborations between writers and objects. Through these practices, students gain a more sophisticated understanding of their own writing processes, teachers gain a more nuanced understanding of the outcomes of their pedagogical choices, and administrators gain a clearer vision of how the classroom itself affects curriculum design and implementation. This argument is pursued in several chapters, each presenting a different method for inciting reflection through the consideration of human/object interaction. The first chapter reviews the literature of object oriented rhetorical theory and reflective teaching practice. The second chapter adapts a methodology from the field of Organizational Science called Narrative Network Analysis (NNA) and leads students through a process of identifying and describing human/object interaction within narratives and asks students to represent these relationships visually. As students undertake this task they can more objectively examine their own writing processes. In the third chapter, video ethnographic methodologies are used to observe object oriented rhetoric theory in practice through the interactions of humans and objects in the writing classroom. Through three video essays, clips of footage taken of a writing classroom and its writing objects are selected and juxtaposed to highlight the agency and influence of objects. In chapter four, a tool developed using freely available cloud-based web applications is presented which is termed the “Fitness Tracker for Teaching.” This tool is used to regularly collect, store, and analyze data that students self-report through a daily class survey about their work efforts, their work environment, and their feelings of confidence, productivity, and self-efficacy. The data gathered through this tool provides a more complete understanding of student effort and affect than could be provided by the teacher’s and students’ own memories or perceptions. Together these chapters provide a set of reflective practices that reinforce teaching writing as a process that is affective and embodied and acknowledges and accounts for the rhetorical agency of objects.Dissertation/ThesisChapter 3 Video PresentationDoctoral Dissertation English 201

Highly Efficient Synthesis of Neat Graphene Nanoscrolls from Graphene Oxide by Well-Controlled Lyophilization

Graphene nanoscroll (GNS) is an important one-dimensional tubular form of graphitic carbon with characteristic open topology. It has been predicted to possess extraordinary properties that are significantly different from the analogical multiwalled carbon nanotubes. However, comprehensive experimental investigations on its properties and applications are still hindered by the lack of its reliable synthesis in high yield. To efficiently transform the scalable graphene oxide sheets into GNSs, here, we proposed a well-controlled lyophilization that comprises four sequential steps: chemical reduction of giant GO, freezing isolation of reduced graphene sheets, freeze-drying, and thermal annealing. The combined method has an extremely high efficiency, up to the record 92%. Systemic control experiments and cryo-SEM inspections revealed that the topological transformation from 2D sheet to 1D scroll is the sublimation-induced scrolling of individually confined graphene sheets in ice, which was controlled by chemical reduction, feed concentration, and freezing rate. GNSs exhibited high structural integration and were solution-processed into macroscopic forms. We also revealed the spontaneous swelling behavior of GNS in a reversible manner for the first time, verifying the featured open topology of GNS. Through this combined protocol, GNS can be scalably synthesized from massive graphene oxide with high efficiency, which should promote comprehensive research and massive applications in the real world

Wet-Spinning of Continuous Montmorillonite-Graphene Fibers for Fire-Resistant Lightweight Conductors

All-inorganic fibers composed of neat 2D crystals possessing fascinating performance (<i>e</i>.<i>g</i>., alternately stacking layers, high mechanical strength, favorable electrical conductivity, and fire-resistance) are discussed in detail. We developed a wet-spinning assmebly strategy to achieve continuous all-inorganic fibers of montmorillonite (MMT) nanoplatelets by incorporation of a graphene oxide (GO) liquid crystal (LC) template at a rate of 9 cm/s, and the templating role of GO LC is confirmed by <i>in situ</i> confocal laser scanning microscopy and polarized optical microscopy inspections. After protofibers underwent thermal reduction, the obtained binary complex fibers composed of neat 2D crystals integrate the outstanding fire-retardance of MMT nanoplatelets and the excellent conductivity of graphene nanosheets. High-resolution transmission electron microscopy and scanning electron microscope observations reveal the microstructures of fibers with compactly stacking layers. MMT-graphene fibers show increaing tensile strengths (88–270 MPa) and electrical conductivities (130–10500 S/m) with increasing graphene fraction. MMT-graphene (10/90) fibers are used as fire-resistant (bearing temperature in air: 600–700 °C), lightweight (ρ < 1.62 g/cm³) conductors (conductivity: up to 1.04 × 10⁴ S/m) in view of their superior performance in high-temperature air beyond commercial T700 carbon fibers. We attribute the fire-resistance of MMT-graphene fibers to the armor-like protection of MMT layers, which could shield graphene layers from the action of oxidative etching. The composite fibers worked well as fire-resistant conductors when being heated to glowing red by an alcohol lamp. Our GO LC-templating wet-spinning strategy may also inspire the continuous assembly of other layered crystals into high-performance composite fibers

Regression example 1 of GA-computed.

<p>This example is deleting <b>using GA</b> 5% of the edges in ≤ −0.9 coupled networks in group 50-200-1000.</p

Regression example 2 of GUROBI-computed.

<p>This example is deleting using GUROBI 5% of the edges in ≥0.9 coupled networks in group 50-200-1000.</p

Relative error for the example.

<p> <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0145421#pone.0145421.g011" target="_blank">Fig 11</a>’s relative error.</p

Linear relation example 2.

<p>Example 2 is deleting <b>using GUROBI</b> 5% of the edges in the ≤ −0.9 coupled networks in group 50-200-1000.</p

Lysine Malonylome May Affect the Central Metabolism and Erythromycin Biosynthesis Pathway in Saccharopolyspora erythraea

Lysine acylation is a dynamic, reversible post-translational modification that can regulate cellular and organismal metabolism in bacteria. Acetylome has been studied well in bacteria. However, to our knowledge, there are no proteomic data on the lysine malonylation in prokaryotes, especially in actinomycetes, which are the major producers of therapeutic antibiotics. In our study, the first malonylome of the erythromycin-producing Saccharopolyspora erythraea was described by using a high-resolution mass spectrometry-based proteomics approach and high-affinity antimalonyllysine antibodies. We identified 192 malonylated sites on 132 substrates. Malonylated proteins are enriched in many biological processes such as protein synthesis, glycolysis and gluconeogenesis, the TCA cycle, and the feeder metabolic pathways of erythromycin synthesis according to GO analysis and KEGG pathway analysis. A total of 238 S/T/Y/H-phosphorylated sites on 158 proteins were also identified in our study, which aimed to explore the potential cross-talk between acylation and phosphorylation. After that, site-specific mutations showed that malonylation is a negative regulatory modification on the enzymatic activity of the acetyl–CoA synthetase (Acs) and glutamine synthetase (Gs). Furthermore, we compared the malonylation levels of the two-growth state to explore the potential effect of malonylation on the erythromycin biosynthesis. These findings expand our current knowledge of the actinomycetes malonylome and supplement the acylproteome databases of the whole bacteria

Relative error for regression example 2 of GUROBI-computed.

<p> <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0145421#pone.0145421.g006" target="_blank">Fig 6</a>’s relative error.</p