Single-step process to improve the mechanical properties of carbon nanotube yarn

Porous Microspheres as Pathogen Traps for Sepsis Therapy: Capturing Active Pathogens and Alleviating Inflammatory Reactions

Sepsis is a systemic inflammatory response syndrome caused by pathogen infection, while the current antibiotics mainly utilized in clinical practice to combat infection result in the release of pathogen-associated molecular patterns (PAMPs) in the body. Herein, we provide an innovative strategy for controlling sepsis, namely, capturing active pathogens by means of extracorporeal blood purification. Carbon nanotubes (CNTs) were modified with dimethyldiallylammonium chloride (DDA) through γ-ray irradiation-induced graft polymerization to confer a positive charge. Then, CNT-DDAs are blended with polyurethane (PU) to prepare porous microspheres using the electro-spraying method. The obtained microspheres with a pore diameter of 2 μm served as pathogen traps and are termed as PU-CNT-DDA microspheres. Even at a high flow rate of 50 mL·min-1, the capture efficiencies of the PU-CNT-DDAs for Escherichia coli and Staphylococcus aureus remained 94.7% and 98.8%, respectively. This approach circumvents pathogen lysis and mortality, significantly curtails the release of PAMPs, and hampers the production of pro-inflammatory cytokines. Therefore, hemoperfusion using porous PU-CNT-DDAs as pathogen traps to capture active pathogens and alleviate inflammation opens a new route for sepsis therapy.

Electrical Properties Enhancement of Carbon Nanotube Yarns by Cyclic Loading

Carbon nanotube yarns (CNTYs) possess low density, high conductivity, high strength, and moderate flexibility. These intrinsic properties allow them to be a preferred choice for use as conductive elements in high-performance composites. To fully exploit their potential as conductive reinforcing elements, further improvement in their electrical conductivity is needed. This study demonstrates that tensile cyclic loading under ambient conditions improves the electrical conductivity of two types of CNTYs. The results showed that the electrical resistance of untreated CNTYs was reduced by 80% using cyclic loading, reaching the resistance value of the drawn acid-treated CNTYs. Scanning electron microscopy showed that cyclic loading caused orientation and compaction of the CNT bundles that make up the CNTYs, resulting in significantly improved electrical conductivity of the CNTYs. Furthermore, the elastic modulus was increased by 20% while preserving the tensile strength. This approach has the potential to replace the environmentally unfriendly acid treatment currently used to enhance the conductivity of CNTYs.

Disorder in H+-irradiated HOPG: effect of impinging energy and dose on Raman D-band splitting and surface topography

Disorder was induced in pristine highly oriented pyrolytic graphite (HOPG) by irradiation with H⁺ ions with energies of 0.4 MeV and 1 MeV, and doses of 10¹⁴ ions/cm² and 10¹⁶ ions/cm². Raman spectroscopy was used as the main technique to characterize different samples and gain new insights on the splitting of the D band into two components (D₁ and D₂), trying to correlate this feature of the vibrational spectrum with the impinging energy and dose. An increased I _D2/I _G ratio in comparison with I _D1/I _G was observed in the irradiated samples. This behavior indicates that the impinging energy mainly affects the D₁ component, while the D₂ component is strongly dominated by the dose. We expect a larger contribution of defects (originating from the rupture of C-C sp² symmetry through the formation of C-H sp³ bonds) to the D₂ component than to the D₁ component. SQUID measurements of the irradiated samples showed an enhancement in the normalized remanence, as well as an increment in coercivity compared to pristine HOPG, consistent with H⁺-induced point-like defects as well as C-H bonds. AFM scanning after Raman and SQUID characterization showed a distribution of surface defects, which were ascribed to the burst of hydrogen blisters formed as a consequence of the irradiation process. The results presented in this work contribute to the current trend in nanotechnology in areas devoted to the control of properties by defect engineering in carbon-based materials.