Polarization-sensitive photodetectors are highly desirable for high-performance optical signal capture and stray light shielding in order to enhance the capability for detection and identification of targets in dark, haze, and other complex environments. Usually, filters and polarizers are utilized for conventional devices to achieve polarization-sensitive detection. Herein, to simplify the optical system, a two-dimensional self-powered polarization-sensitive photodetector is fabricated based on a stacked GeSe/MoS2 van der Waals (vdW) heterojunction which facilitates efficient separation and transportation of the photogenerated carriers because of type-II band alignment. Accordingly, a high-performance self-powered photodetector is achieved with merits of a very large on–off ratio photocurrent at zero bias of currently 104 and a high responsivity (R λ) of 105 mA/W with an external quantum efficiency of 24.2%. Furthermore, a broad spectral photoresponse is extended from 380 to 1064 nm owing to the high absorption coefficient in a wide spectral region. One of the key benefits from these highly anisotropic orthorhombic structures of layered GeSe is self-powered polarization-sensitive detection with a peak/valley ratio of up to 2.95. This is realized irradiating with a 532 nm wavelength laser with which a maximum photoresponsivity of up to 590 mA/W is reached when the input polarization is parallel to the armchair direction. This work provides a facile route to fabricate self-powered polarization-sensitive photodetectors from GeSe/MoS2 vdW heterojunctions for integrated optoelectronic devices.

Cellular morphology and associated morphodynamics are widely used for qualitative and quantitative assessments of cell state. Here we implement a framework to profile cellular morphodynamics based on an adaptive decomposition of local cell boundary motion into instantaneous frequency spectra defined by the Hilbert-Huang transform (HHT). Our approach revealed that spontaneously migrating cells with approximately homogeneous molecular makeup show remarkably consistent instantaneous frequency distributions, though they have markedly heterogeneous mobility. Distinctions in cell edge motion between these cells are captured predominantly by differences in the magnitude of the frequencies. We found that acute photo-inhibition of Vav2 guanine exchange factor, an activator of the Rho family of signaling proteins coordinating cell motility, produces significant shifts in the frequency distribution, but does not affect frequency magnitude. We therefore concluded that the frequency spectrum encodes the wiring of the molecular circuitry that regulates cell boundary movements, whereas the magnitude captures the activation level of the circuitry. We also used HHT spectra as multi-scale spatiotemporal features in statistical region merging to identify subcellular regions of distinct motion behavior. In line with our conclusion that different HHT spectra relate to different signaling regimes, we found that subcellular regions with different morphodynamics indeed exhibit distinct Rac1 activities. This algorithm thus can serve as an accurate and sensitive classifier of cellular morphodynamics to pinpoint spatial and temporal boundaries between signaling regimes.

Mechanical overload of the vascular wall is a pathological hallmark of life-threatening abdominal aortic aneurysms (AAA). However, how this mechanical stress resonates at the unicellular level of vascular smooth muscle cells (VSMC) is undefined. Here we show defective mechano-phenotype signatures of VSMC in AAA measured with ultrasound tweezers-based micromechanical system and single-cell RNA sequencing technique. Theoretical modelling predicts that cytoskeleton alterations fuel cell membrane tension of VSMC, thereby modulating their mechanoallostatic responses which are validated by live micromechanical measurements. Mechanistically, VSMC gradually adopt a mechanically solid-like state by upregulating cytoskeleton crosslinker, α-actinin2, in the presence of AAA-promoting signal, Netrin-1, thereby directly powering the activity of mechanosensory ion channel Piezo1. Inhibition of Piezo1 prevents mice from developing AAA by alleviating pathological vascular remodeling. Our findings demonstrate that deviations of mechanosensation behaviors of VSMC is detrimental for AAA and identifies Piezo1 as a novel culprit of mechanically fatigued aorta in AAA.

Organic bulk heterojunction photodiodes (OPDs) attract attention for sensing and imaging. Their detectivity is typically limited by a substantial reverse bias dark current density (Jd). Recently, using thermal admittance or spectral photocurrent measurements, Jd has been attributed to thermal charge generation mediated by mid‐gap states. Here, the temperature dependence of Jd in state‐of‐the‐art OPDs is reported with Jd down to 10−9 mA cm−2 at −0.5 V bias. For a variety of donor‐acceptor bulk‐heterojunction blends it is found that the thermal activation energy of Jd is lower than the effective bandgap of the blends, by ca. 0.3 to 0.5 eV, but higher than expected for mid‐gap states. Ultra‐sensitive sub‐bandgap photocurrent spectroscopy reveals that the minimum photon energy for optical charge generation in OPDs correlates with the dark current thermal activation energy. The dark current in OPDs is attributed to thermal charge generation at the donor‐acceptor interface mediated by intra‐gap states near the band edges.

Molecular sieves ensure proper pairing of tRNAs and amino acids during aminoacyl-tRNA biosynthesis, thereby avoiding detrimental effects of mistranslation on cell growth and viability. Mischarging errors are often corrected through the activity of specialized editing domains present in some aminoacyl-tRNA synthetases or via single-domain -editing proteins. ProXp-ala is a ubiquitous-editing enzyme that edits Ala-tRNA, the product of Ala mischarging by prolyl-tRNA synthetase, although the structural basis for discrimination between correctly charged Pro-tRNA and mischarged Ala-tRNA is unclear. Deacylation assays using substrate analogs reveal that size discrimination is only one component of selectivity. We used NMR spectroscopy and sequence conservation to guide extensive site-directed mutagenesis of ProXp-ala, along with binding and deacylation assays to map specificity determinants. Chemical shift perturbations induced by an uncharged tRNA acceptor stem mimic, microhelix, or a nonhydrolyzable mischarged Ala-microhelix substrate analog identified residues important for binding and deacylation. Backbone N NMR relaxation experiments revealed dynamics for a helix flanking the substrate binding site in free ProXp-ala, likely reflecting sampling of open and closed conformations. Dynamics persist on binding to the uncharged microhelix, but are attenuated when the stably mischarged analog is bound. Computational docking and molecular dynamics simulations provide structural context for these findings and predict a role for the substrate primary α-amine group in substrate recognition. Overall, our results illuminate strategies used by a-editing domain to ensure acceptance of only mischarged Ala-tRNA, including conformational selection by a dynamic helix, size-based exclusion, and optimal positioning of substrate chemical groups.