CRISPR-Cas systems have revolutionized genome editing across a broad range of biotechnological endeavors. Many CRISPR-Cas nucleases have been identified and engineered for improved capabilities. ...Given the modular structure of such enzymes, we hypothesized that engineering chimeric sequences would generate non-natural variants that span the kinetic parameter landscape, and thus provide for the rapid selection of nucleases fit for a particular editing system. Here, we design a chimeric Cas12a-type library with approximately 560 synthetic chimeras, and select several functional variants. We demonstrate that certain nuclease domains can be recombined across distantly related nuclease templates to produce variants that function in bacteria, yeast, and human cell lines. We further characterize selected chimeric nucleases and find that they have different protospacer adjacent motif (PAM) preferences and the M44 chimera has higher specificity relative to wild-type (WT) sequences. This demonstration opens up the possibility of generating nuclease sequences with implications across biotechnology.
Depositing a pinhole-free perovskite film is of paramount importance to achieve high performance perovskite solar cells, especially in a heterojunction device format that is free of hole transport ...material (HTM). Here, we report that high-quality pinhole-free CH3NH3PbI3 perovskite film can be controllably deposited via a facile low-temperature (<150 °C) gas–solid crystallization process. The crystallite formation process was compared with respect to the conventional solution approach, in which the needle-shaped solvation intermediates (CH3NH3PbI3·DMF and CH3NH3PbI3·H2O) have been recognized as the main cause for the incomplete coverage of the resultant film. By avoiding these intermediates, the films crystallized at the gas–solid interface offer several beneficial features for device performance including high surface coverage, small surface roughness, as well as controllable grain size. Highly efficient HTM-free perovskite solar cells were constructed with these pinhole-free CH3NH3PbI3 films, exhibiting significant enhancement of the light harvesting in the long wavelength regime with respect to the conventional solution processed one. Overall, the gas–solid method yields devices with an impressive power conversion efficiency of 10.6% with high reproducibility displaying a negligible deviation of 0.1% for a total of 30 cells.
A two-dimensional electrodynamical model is used to study particle acceleration in the outer magnetosphere of a pulsar. The charge depletion from the Goldreich-Julian charge density causes a large ...electric field along the magnetic field lines. The charge particles are accelerated by the electric field and emit γ-rays via the curvature process. Some of the emitted γ-rays may collide with X-ray photons to make new pairs, which are accelerated again on the different field lines and emit γ-rays. We simulate the pair creation cascade in the meridional plane using the pair creation mean-free path, in which the X-ray photon number density is proportional to the inverse square of the radial distance. With the space charge density determined by the pair creation simulation, we solve the electric structure of the outer gap in the meridional plane and calculate the curvature spectrum. We investigate in detail the relation between the spectrum and total current, which is carried by the particles produced in the gap and/or injected at the boundaries of the gap. We demonstrate that the hardness of the spectrum is strongly controlled by the current carriers. Especially, the spectrum sharply softens if we assume a larger particle injection at the outer boundary of the outer gap. This is because the mean-free path of the pair creation of the inwardly propagating γ-ray photons is much shorter than the light radius, so many pairs are produced in the gap to quench the outer gap. Because the two-dimensional model can link both gap width along the magnetic field line and trans-field thickness with the spectral cut-off energy and flux, we can diagnose both the current through the gap and the inclination angle between the rotational and magnetic axes. We apply the theory to the Vela pulsar. By comparing the results with the Energetic Gamma Ray Experiment Telescope (EGRET) data, we rule out any cases that have a large particle injection at the outer boundary. We also suggest the inclination angle of αinc≥ 65°. The present model predicts the outer gap starting from near the conventional null charge surface for the Vela pulsar.
The development of bromodomain and extraterminal domain (BET) bromodomain inhibitors and their examination in clinical studies, particularly in oncology settings, has garnered substantial recent ...interest. An effort to generate novel BET bromodomain inhibitors with excellent potency and drug metabolism and pharmacokinetics (DMPK) properties was initiated based upon elaboration of a simple pyridone core. Efforts to develop a bidentate interaction with a critical asparagine residue resulted in the incorporation of a pyrrolopyridone core, which improved potency by 9–19-fold. Additional structure–activity relationship (SAR) efforts aimed both at increasing potency and improving pharmacokinetic properties led to the discovery of the clinical candidate 63 (ABBV-075/mivebresib), which demonstrates excellent potency in biochemical and cellular assays, advantageous exposures and half-life both in animal models and in humans, and in vivo efficacy in mouse models of cancer progression and inflammation.
Abstract Extravillus trophoblast (EVT) invasion plays a critical role in placental development. Integrins bind to extracellular matrix (ECM) proteins to mediate EVT cell adhesion, migration, and ...invasion. Changes in O -glycans on β1-integrin have been found to regulate cancer cell behavior. We hypothesize that O -glycosyltransferases can regulate EVT invasion through modulating the glycosylation and function of β1-integrin. Here, we found that the GALNT1 and GALNT2 mRNA were highly expressed in HTR8/SVneo and first trimester EVT cells. Immunohistochemstry and immunofluorescence staining showed that GALNT2 was expressed in subpopulations of EVT cells in deciduas, but not in syncytiotrophoblasts and cytotrophoblasts of placental villi. The percentage of GALNT2-positive EVT cells increased with gestational ages. Overexpression of GALNT2 in HTR8/SVneo cells significantly enhanced cell-collagen IV adhesion, but suppressed cell migration and invasion. Notably, we found that GALNT2 increased the expression of Tn antigen (GalNAc-Ser/Thr) on β1-integrin as revealed by Vicia Villosa agglutinin (VVA) binding. Furthermore, GALNT2 suppressed the phosphorylation of focal adhesion kinase (FAK), a crucial downstream signaling molecule of β1-integrin. Our findings suggest that GALNT2 is a critical initiating enzyme of O -glycosylation for regulating EVT invasion.
We present the first formation of the previously elusive phosphine imide (HN&z.dbd;PH
3
) along with its phosphinous amide (H
2
N-PH
2
) isomer
via
exposure of phosphine (PH
3
) and ammonia (NH
3
) ...ices to ionizing radiation. Our approach may be extended to prepare, separate, and detect highly reactive compounds such as intermediates of Wittig reactions.
Phosphine imide (HN&z.dbd;PH
3
)-the simplest iminophosphorane-and phosphinous amide (H
2
N-PH
2
) were prepared by exposing phosphine-ammonia ices to ionizing radiation.
We hereby present a simple process, called in situ two-end diffusion (TED), to reach coercivity enhancement with almost unchanged energy product for hot deformed (HD) NdFeB magnets. Coercivity of the ...HD magnets is increased from 15.1 to 18.7 kOe for the magnet TED with (Nd0.75Pr0.25)70Cu30 (NdPrCu), which is larger than 17.6 kOe for the magnet directly doped with 2 wt. % NdPrCu alloy. Besides, the magnet TED with NdPrCu exhibits good (00L) texture and therefore could support high (BH)max of 43.0 MGOe. In addition, the magnet TED with Ce70Cu30 (CeCu) exhibit superior magnetic properties of Br = 12.8 kG, iHc = 18.0 kOe and (BH)max = 40.7 MGOe to those of traditional doping with CeCu (Br = 11.7 kG, iHc = 16.4 kOe and (BH)max = 34.2 MGOe). For TED process, low-melting CeCu can infiltrate into the center of the magnet, and most Ce distribute at grain boundary. The distribution of Ce and Cu at grain boundary can reduce the magnetization of grain boundary phase, strengthen the decoupling effect between grains and contribute to the coercivity enhancement. This work demonstrates TED with low-melting HRE-free alloys is a simple method to effectively enhance coercivity and keep high Br and (BH)max for HD NdFeB magnets.
•PrFeB films on Ta underlayer show perpendicular magnetic anisotropy (PMA).•The magnetic properties highly depend on the thickness of Ta underlayer (t).•High PMA with out-of-plane coercivity ...Hc⊥>800kA/m is attained at t=50nm.•High Hc⊥ originates from fine 2:14:1 grain and Pr-rich grain boundary phase.
Perpendicular magnetic anisotropy (PMA) of sputter-prepared Pr–Fe–B films on the glass substrates were improved by inserting a Ta underlayer. Pr–Fe–B directly sputtered on glass substrate exhibits soft in-plane magnetic property due to the amorphous phase or poor crystallization. When Ta layer is introduced as an underlayer, strong PMA with attractive hard magnetic properties are obtained. Their magnetic properties highly depend on the thickness of Ta underlayer (t). Large out-of-plane coercivity (Hc⊥>800kA/m) is attained for t in the range of 10–75nm, where the Pr–Fe–B film sputtered on 50-nm-thick Ta underlayer shows stronger PMA due to promotion of the formation for the Pr2Fe14B phase with Ta underlayer. Therefore, it was demonstrated that inserting a Ta underlayer with suitable t (∼50nm) between magnetic layer and glass substrate promotes to obtain Pr–Fe–B film with excellent PMA.
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