Carbon-dot doped, transfer-free, low-temperature, high mobility graphene using microwave plasma CVD

Carbon dots: Types, preparation, and their boosted antibacterial activity by photoactivation. Current status and future perspectives

Carbon dots (CDs) correspond to carbon-based materials (CBM) with sizes usually below 10 nm. These nanomaterials exhibit attractive properties such us low toxicity, good stability, and high conductivity, which have promoted their thorough study over the past two decades. The current review describes four types of CDs: carbon quantum dots (CQDs), graphene quantum dots (GQDs), carbon nanodots (CNDs), and carbonized polymers dots (CPDs), together with the state of the art of the main routes for their preparation, either by "top-down" or "bottom-up" approaches. Moreover, among the various usages of CDs within biomedicine, we have focused on their application as a novel class of broad-spectrum antibacterial agents, concretely, owing their photoactivation capability that triggers an enhanced antibacterial property. Our work presents the recent advances in this field addressing CDs, their composites and hybrids, applied as photosensitizers (PS), and photothermal agents (PA) within antibacterial strategies such as photodynamic therapy (PDT), photothermal therapy (PTT), and synchronic PDT/PTT. Furthermore, we discuss the prospects for the possible future development of large-scale preparation of CDs, and the potential for these nanomaterials to be employed in applications to combat other pathogens harmful to human health. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

Research and application of plasma characteristic models for pulsed laser processing of metal materials

Plasma characteristic models were established in cylindrical coordinates according to the plasma expansion characteristics of pulsed laser processing of metal materials, mainly including plasma expansion characteristic models and a change rate model for the collisional ionization effect. The plasma characteristics (expansion dimension, expansion velocity, electron density and collision rate) for the pulsed laser machining of a bronze grinding wheel were obtained by using the plasma characteristic models. The results show that the expansion velocity direction can be changed after plasma collision, resulting in particles returning and depositing onto the processed material surface. Plasma spectrum measurements for the pulsed laser machining of a bronze grinding wheel and grinding tests were carried out. Based on the measured spectral data, the plasma electron temperature and plasma electron density were calculated, and the topography of the machined grinding wheel surface was observed, which confirms that black particles can return to cover the grinding wheel surface. Through grinding experiments, it is verified that the returning particles reduce the height of the abrasive protruding binder and block the chip space around the abrasive particles, resulting in reduced grinding performance. The experimental calculation data and numerical simulation results are basically consistent with each other, which not only verifies the correctness and feasibility of the plasma characteristic models but also provides theoretical guidance and process optimization for subsequent research into laser machining of materials.