Synthesis and protection: a controllable electrochemical approach to polypyrrole-coated copper azide with superior safety for MEMS.

Traditional lead-based primary explosives present challenges in application to micro-energetics-on-a-chip. It is highly desired but still remains challenging to design a primary explosive for the development of powerful yet safe energetic films. Copper-based azides (Cu(N3)2 or CuN3, CA) are expected to be ideal alternatives owing to their properties such as excellent device compatibility, excellent detonation performance, and low environmental pollution. However, the significantly high electrostatic sensitivity of CA limits its use in micro-electro-mechanical systems (MEMS). This study presents an in situ electrochemical approach to preparing and modifying a CA film with excellent electrostatic safety using a Cu chip. Herein, a CA film is prepared by employing Cu nanorod arrays as precursors. Next, polypyrrole (PPy) is directly coated on the surface of the CA materials to produce a CA@PPy composite energetic film using the electrochemical process. The results show that CuN3 is first generated and gradually oxidized to Cu(N3)2, essentially forming enclosed nest-like structures during electrochemical azidation. The microstructure and composition of the product can be regulated by varying the current density and reaction time, which leads to controllable heat output of the CA from 521 to 1948 J g-1. Notably, the composite energetic film exhibits excellent electrostatic sensitivity (2.69 mJ) owing to the excellent conductivity of PPy. Thus, this study offers novel ideas for the further advances of composite energetic materials and applications in MEMS explosive systems.

Mesenchymal Stem Cell-derived Exosomes Affect Macrophage Phenotype: A Cell-free Strategy for the Treatment of Skeletal Muscle Disorders.

The process of tissue damage, repair, and regeneration in the skeletal muscle system involves complex inflammatory processes. Factors released in the inflammatory microenvironment can affect the phenotypic changes of macrophages, thereby changing the inflammatory process, making macrophages an important target for tissue repair treatment. Mesenchymal stem cells exert anti-inflammatory effects by regulating immune cells. In particular, exosomes secreted by mesenchymal stem cells have become a new cell-free treatment strategy due to their low tumorigenicity and immunogenicity. This article focuses on the mechanism of the effect of exosomes derived from mesenchymal stem cells on the phenotype of macrophages after skeletal muscle system injury and explores the possible mechanism of macrophages as potential therapeutic targets after tissue injury.

Valence-Oriented Electrosynthesis Strategies of Cu-Based 5-Nitrotetrazolate for Environmentally Acceptable Primary Explosives.

The development of green primary explosives has become a "holy grail" of energetic materials research. Cu-based 5-nitrotetrazolate is considered one of the most promising candidates due to its excellent blasting power and environmentally benign nature. However, synthesizing Cu-based 5-nitrotetrazolate controllably and securely remains highly challenging. Herein, room-temperature anodization of metallic Cu and a Cu(I)-imidazole nanowire array on copper substrates in a sodium 5-nitrotetrazolate electrolyte leads to in situ electrosynthesis of Cu(I) 5-nitrotetrazolate (DBX-1, CuNT) and its analogue, Cu(II) 5-nitrotetrazolate [Cu(NT)2], respectively. Both obtained CuNT and Cu(NT)2 films demonstrate remarkable energy output and good laser-induced ignition performance. The thermal stability (Tp = 291 °C) and electrostatic safety (E50 = 2.54 mJ) of CuNT proved to be superior to those of Cu(NT)2 (Tp = 257 °C, and E50 = 0.57 mJ). Remarkably, this study provides an exciting new method for the rational design and development of Cu-based 5-nitrotetrazolate as a primary explosive for advanced initiating applications.

D-Dimer Level Predicts Angiographic No-Reflow Phenomenon After Percutaneous Coronary Intervention Within 2-7 Days of Symptom Onset in Patients with ST-Segment Elevation Myocardial Infarction.

It remains uncertain whether plasma D-dimer level can predict no-reflow in patients with STEMI who had pPCI after 48 h of symptom onset. This study retrospectively enrolled 229 consecutive patients who had pPCI for acute STEMI within 2-7 days of symptom onset between January 2008 and December 2018. Patients were divided into no-reflow group (TIMI flow grade 0-2) and reflow group (TIMI flow grade 3). Predictors of no-reflow were assessed by univariate and multivariate binary logistic regression analyses. Plasma D-dimer level can independently predict no-reflow in patients with STEMI who had pPCI within 2-7 days of symptom onset (OR 2.52 per 1 mg/L increase, 95% CI 1.16-5.47, p = 0.019). This finding indicated that pPCI may be safe and feasible for STEMI patients within 2-7 days of symptom onset with low D-dimer level. Graphical Abstract Plasma D-dimer level can independently predict no-reflow in patients with STEMI who had pPCI within 2-7 days of symptom onset. pPCI may be safe and feasible for STEMI patients within 2-7 days of symptom onset with low D-dimer level.