Electronic friction is a correction to the Born-Oppenheimer approximation, whereby nuclei in motion experience a drag in the presence of a manifold of electronic states. The notion of electronic friction has a long history and has been (re-)discovered in the context of a wide variety of different chemical and physical systems including, but not limited to, surface scattering events, surface reactions or chemisorption, electrochemistry, and conduction through molecular-(or nano-) junctions. Over the years, quite a few different forms of electronic friction have been offered in the literature. In this perspective, we briefly review these developments of electronic friction, highlighting the fact that we can now isolate a single, unifying form for (Markovian) electronic friction. We also focus on the role of electron-electron interactions for understanding frictional effects and offer our thoughts on the strengths and weaknesses of using electronic friction to model dynamics in general.
We present a compact and lightweight 1.5 {\mu}m lidar using a free-runningsingle-photon detector (SPD) based on a multi-mode fiber (MMF) couplingInGaAs/InP negative feedback avalanche diode. The ultimate light detectionsensitivity of SPD highly reduces the power requirement of laser, whilst theenhanced collection efficiency due to MMF coupling significantly reduces thevolume and weight of telescopes. We develop a specific algorithm for thecorrections of errors caused by the SPD and erbium-doped fiber amplifier toextract accurate backscattering signals. We also perform a comparison betweensingle-mode fiber (SMF) coupling and MMF coupling in the lidar receiver, andthe results show that the collection efficiency with MMF coupling is five timeshigher than SMF coupling. In order to validate the functionality, we use thelidar system for the application of cloud detection. The lidar system exhibitsthe ability to detect both the cloud base height and the thickness ofmulti-layer clouds to an altitude of 12 km with a temporal resolution of 1 sand a spatial resolution of 15 m. Due to the advantages of compactness andlightweight, our lidar system can be installed on unmanned aerial vehicles forwide applications in practice.
A biodegradable drug delivery system (DDS) is one the most promising therapeutic strategies for cancer therapy. Here, we propose a unique concept of light activation of black phosphorus (BP) at hydrogel nanostructures for cancer therapy. A photosensitizer converts light into heat that softens and melts drug-loaded hydrogel-based nanostructures. Drug release rates can be accurately controlled by light intensity, exposure duration, BP concentration, and hydrogel composition. Owing to sufficiently deep penetration of near-infrared (NIR) light through tissues, our BP-based system shows high therapeutic efficacy for treatment of s.c. cancers. Importantly, our drug delivery system is completely harmless and degradable in vivo. Together, our work proposes a unique concept for precision cancer therapy by external light excitation to release cancer drugs. If these findings are successfully translated into the clinic, millions of patients with cancer will benefit from our work.
Significance The steady-state levels of miRNAs are under sophisticated control to ensure their proper functions such as development and responses to environmental stimuli. Nevertheless, enzymes responsible for the degradation of various forms of unmethylated miRNAs remain enigmatic, which largely impedes our understanding of miRNA homeostasis and active turnover. Here we report a 3′ to 5′ exoribonuclease Atrimmer 2 that may degrade unmethylated miRNAs in their miRNA/miRNA* duplex status, at places distinct from their production sites (i.e., Dicing bodies). Our study not only increases the complexity of miRNA surveillance, but also provides clues into how nascent miRNA/miRNA* duplexes undergo methylation and RNA-induced silencing complex loading, which is a big challenge in the plant small RNA field.
N -acyl amino acids (NAAs) are a structurally diverse class of bioactive signaling lipids whose endogenous functions have largely remained uncharacterized. To clarify the physiologic roles of NAAs, we generated mice deficient in the circulating enzyme peptidase M20 domain-containing 1 (PM20D1). Global PM20D1-KO mice have dramatically reduced NAA hydrolase/synthase activities in tissues and blood with concomitant bidirectional dysregulation of endogenous NAAs. Compared with control animals, PM20D1-KO mice exhibit a variety of metabolic and pain phenotypes, including insulin resistance, altered body temperature in cold, and antinociceptive behaviors. Guided by these phenotypes, we identify N -oleoyl-glutamine (C18:1-Gln) as a key PM20D1-regulated NAA. In addition to its mitochondrial uncoupling bioactivity, C18:1-Gln also antagonizes certain members of the transient receptor potential (TRP) calcium channels including TRPV1. Direct administration of C18:1-Gln to mice is sufficient to recapitulate a subset of phenotypes observed in PM20D1-KO animals. These data demonstrate that PM20D1 is a dominant enzymatic regulator of NAA levels in vivo and elucidate physiologic functions for NAA signaling in metabolism and nociception.