Multi-sites energy transfer in Fe3+-doped KAl11O17 phosphor toward zero thermal quenching near-infrared luminescence.

Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) have demonstrated great potential for optoelectronic and biomedical applications, while the exploration of NIR phosphors with high thermal stability remains a challenge. Herein, we report an NIR phosphor KAl11O17:Fe3+ with zero thermal quenching (TQ) behavior up to 200°C. The asymmetrical broadband NIR emission with three sub-bands centered at 700, 770, and 800 nm is related to the superposition of different Fe3+ emission centers located in Al2O4, Al3O6, and Al4O6 sites of the KAl11O17 host, respectively. Temperature- and Fe3+ concentration-dependent emission spectra verify that the energy transfer (ET) between multiple Fe3+ emitters and the weak electron-phonon coupling (EPC) effect contribute to the thermally stable broadband NIR emission. The fabricated NIR pc-LED using optimized KAl11O17:Fe3+ phosphor exhibits great potential in information encryption applications.

Visible and Near-Infrared Emission in Ba3Sc4O9:Bi Phosphor: An Investigation on Bismuth Valence Modification.

Bismuth (Bi)-activated luminescence materials have attracted much attention for their tunable broad emissions ranging from a visible to near-infrared (NIR) region. However, it remains a challenge to regulate the Bi valence state and achieve NIR emission via a facile way. Here, we report the design and preparation of Ba3Sc4O9:Bi phosphors, which emit visible and NIR emissions simultaneously even prepared in the air condition. The self-reduction mechanism of Bi3+ species in Ba3Sc4O9 with a rigid crystal structure is illustrated based on the charge compensation model, and the coexistence of different Bi-active centers, Bi3+ for visible emission, while Bi+ and Bi0 for NIR emission, is confirmed by the spectroscopic data and X-ray photoelectron spectroscopy (XPS) analysis. The enhanced NIR emission was further achieved through controlled reducing treatment and the related mechanism has also been clarified. This work paves a new way to control bismuth valence and tune the emission of Bi-based luminescence materials for emerging photonics applications.

[Research on algorithms of uterine contraction curve analysis and its real-time status identification].

Identification of real-time uterine contraction status is very significant to labor analgesia, but the traditional uterine contraction analysis algorithms and systems cannot meet the requirement. According to the situations mentioned above, this paper designs a set of algorithms for the real-time analysis of uterine contraction status. The algorithms include uterine contraction signal preprocessing, uterine contraction baseline extraction based on histogram and linear iteration and an algorithm for the real-time analysis of uterine contraction status based on finite state machines theory. It uses the last uterine status and a series of state transfer conditions to identify the current uterine contraction status, as well as a buffer mechanism to avoid false status transitions. To evaluate the performance of the algorithm, we compare it with an existing uterine contraction analysis algorithm used in the electronic fetal monitor. The experiments show that our algorithm can analyze the uterine contraction status while monitoring the uterine contraction signal in a real-time. Its sensitivity reaches 0.939 9 and its positive predictive value is 0.869 3, suggesting that the algorithm has high accuracy and meets the need of clinical monitoring.

DeepPicker: A deep learning approach for fully automated particle picking in cryo-EM.

Particle picking is a time-consuming step in single-particle analysis and often requires significant interventions from users, which has become a bottleneck for future automated electron cryo-microscopy (cryo-EM). Here we report a deep learning framework, called DeepPicker, to address this problem and fill the current gaps toward a fully automated cryo-EM pipeline. DeepPicker employs a novel cross-molecule training strategy to capture common features of particles from previously-analyzed micrographs, and thus does not require any human intervention during particle picking. Tests on the recently-published cryo-EM data of three complexes have demonstrated that our deep learning based scheme can successfully accomplish the human-level particle picking process and identify a sufficient number of particles that are comparable to those picked manually by human experts. These results indicate that DeepPicker can provide a practically useful tool to significantly reduce the time and manual effort spent in single-particle analysis and thus greatly facilitate high-resolution cryo-EM structure determination. DeepPicker is released as an open-source program, which can be downloaded from https://github.com/nejyeah/DeepPicker-python.

Modulation of Thermally Stable Photoluminescence in Cr3+-Based Near-Infrared Phosphors.

Broadband near-infrared (NIR) light sources based on phosphor-converted light-emitting diodes (pc-LEDs) are desirable for various photonics applications, while developing thermally stable NIR phosphors remains a great challenge. Increasing the temperature accelerates the severe nonradiative relaxation process gorverned by the intrinsic energy gap law, which further suspends the efficient low-energy emission of Cr3+ emitters in the inorganic lattice. To address this rule, several state-of-the-art strategies have been put forward in this perspective to modulate the critical law from the viewpoints of (1) crystal structure design, (2) defect engineering, (3) strengthened rigidity, and (4) energy transfer. This perspective suggests avenues for exploring novel broadband NIR phosphors with high thermal stability and will also stimulate further studies on NIR spectroscopy for high-power applications.

Li/Na substitution and Yb3+ co-doping enabling tunable near-infrared emission in LiIn2SbO6:Cr3+ phosphors for light-emitting diodes.

Near-infrared (NIR) phosphor-converted light-emitting diode (pc-LED) has great potential in non-invasive detection, while the discovery of tunable broadband NIR phosphor still remains a challenge. Here, we report that Cr3+-activated LiIn2SbO6 exhibits a broad emission band ranging from 780 to 1400 nm with a full width at half maximum (FWHM) of 225 nm upon 492 nm excitation. The emission peaks are tuned from 970 to 1020 nm together with considerable broadening of FWHM (∼285 nm) via Li/Na substitution. Depending on Yb3+ co-doping, a stronger NIR fluorescence peak of Yb3+ appears with improved thermal resistance, which is ascribed to efficient energy transfer from Cr3+ to Yb3+. An NIR pc-LED package has been finally designed and demonstrated a remarkable ability to penetrate pork tissues (∼2 cm) so that the insertion depth of a needle can be observed, indicating that the phosphor can be applied in non-destructive monitoring.

A cell-permeable peptide-based PROTAC against the oncoprotein CREPT proficiently inhibits pancreatic cancer.

Cancers remain a threat to human health due to the lack of effective therapeutic strategies. Great effort has been devoted to the discovery of drug targets to treat cancers, but novel oncoproteins still need to be unveiled for efficient therapy. Methods: We show that CREPT is highly expressed in pancreatic cancer and is associated with poor disease-free survival. CREPT overexpression promotes but CREPT deletion blocks colony formation and proliferation of pancreatic cancer cells. To provide a proof of concept for CREPT as a new target for the inhibition of pancreatic cancer, we designed a cell-permeable peptide-based proteolysis targeting chimera (PROTAC), named PRTC, based on the homodimerized leucine-zipper-like motif in the C-terminus domain of CREPT to induce its degradation in vivo. Results: PRTC has high affinity for CREPT, with Kd = 0.34 +/- 0.11 µM and is able to permeate into cells because of the attached membrane-transportable peptide RRRRK. PRTC effectively induces CREPT degradation in a proteasome-dependent manner. Intriguingly, PRTC inhibits colony formation, cell proliferation, and motility in pancreatic cancer cells and ultimately impairs xenograft tumor growth, comparable to the effect of CREPT deletion. Conclusions: PRTC-induced degradation of CREPT leads to inhibition of tumor growth, which is promising for the development of new drugs against pancreatic cancer. In addition, using an interacting motif based on the dimerized structure of proteins may be a new way to design a PROTAC aiming at degrading any protein without known interacting small molecules or peptides.

Mammalian ALKBH1 serves as an N6-mA demethylase of unpairing DNA.

N6-methyladenine (N6-mA) of DNA is an emerging epigenetic mark in mammalian genome. Levels of N6-mA undergo drastic fluctuation during early embryogenesis, indicative of active regulation. Here we show that the 2-oxoglutarate-dependent oxygenase ALKBH1 functions as a nuclear eraser of N6-mA in unpairing regions (e.g., SIDD, Stress-Induced DNA Double Helix Destabilization regions) of mammalian genomes. Enzymatic profiling studies revealed that ALKBH1 prefers bubbled or bulged DNAs as substrate, instead of single-stranded (ss-) or double-stranded (ds-) DNAs. Structural studies of ALKBH1 revealed an unexpected "stretch-out" conformation of its "Flip1" motif, a conserved element that usually bends over catalytic center to facilitate substrate base flipping in other DNA demethylases. Thus, lack of a bending "Flip1" explains the observed preference of ALKBH1 for unpairing substrates, in which the flipped N6-mA is primed for catalysis. Co-crystal structural studies of ALKBH1 bound to a 21-mer bulged DNA explained the need of both flanking duplexes and a flipped base for recognition and catalysis. Key elements (e.g., an ALKBH1-specific α1 helix) as well as residues contributing to structural integrity and catalytic activity were validated by structure-based mutagenesis studies. Furthermore, ssDNA-seq and DIP-seq analyses revealed significant co-occurrence of base unpairing regions with N6-mA in mouse genome. Collectively, our biochemical, structural and genomic studies suggest that ALKBH1 is an important DNA demethylase that regulates genome N6-mA turnover of unpairing regions associated with dynamic chromosome regulation.