Abstract The direct C−H functionalization of 1,2‐benzazaborines, especially asymmetric version, remains a great challenge. Here we report a palladium‐catalyzed enantioselective C−H olefination and allylation reactions of 1,2‐benzazaborines. This asymmetric approach is a kinetic resolution (KR), providing various C−B axially chiral 2‐aryl‐1,2‐benzazaborines and 3‐substituted 2‐aryl‐1,2‐benzazaborines in generally high yields with excellent enantioselectivities (selectivity (S) factor up to 354). The synthetic potential of this reaction is showcased by late‐stage modification of complex molecules, scale‐up reaction, and applications.
Early rectal neoplasms can be treated endoscopically with good prognosis, yet usually present with unspecific or an absence of signs and symptoms and are detected largely by invasive endoscopy with less compliance to screening. The purpose of this cross-sectional study was to explore the diagnostic value of dual-layer spectral detector computed tomography (DSCT) imaging for early rectal neoplasm. Patients who underwent DSCT for evaluation of rectal lesion or routine examination between September 2022 to September 2023 at West China Hospital were prospectively included and identified as group A (control, n=76), group B (rectal advanced adenomas and ≤T1 rectal cancer, n=59), and group C (≥T2 staging rectal cancer, n=74). Lesion visualization was graded to assess image quality. Spectral quantitative measurement, such as Hounsfield unit (HU)40 keV, HU70 keV, iodine concentration (IC), effective atomic number (Zeff), and the slope of spectral curve (λ), was analyzed and compared. Receiver operating characteristic (ROC) curves were generated to evaluate the diagnostic efficacy of spectral parameters. A comparison of ROC curves was applied to test the significance of differences between the area under the curves (AUCs). Compared to poly-energetic images (PEIs), the multiple parameters from DSCT were of greater capability to recognize rectal lesions. There were significant differences in HU40 keV (208.01±43.60 vs. 255.53±45.16), HU70 keV (87.06±18.55 vs. 100.78±18.26), IC [1.91 (1.71, 2.28) vs. 2.58±0.49], Zeff [8.33 (8.25, 8.50) vs. 8.61±0.20], and λ [3.80 (3.41, 4.52) vs. 5.16±1.00] between the early neoplastic lesions in rectum and the advanced rectal cancer (P<0.001). Significant correlations were found between the DSCT parameters and tumor staging (P<0.001). Furthermore, the AUCs of IC, Zeff, λ, and HUPEI were all above 0.90 for early rectal neoplasm detection, with additional capability of discriminating early rectal neoplasm from advanced rectal cancer. DSCT improved tumor conspicuity and the detection of the early rectal neoplastic lesion, suggesting that it is a promising screening tool in clinical practice.
Ketonization of oxygenated compounds in pyrolytic products of biomass is an effective means for deoxygenation and upgrading of bio-oils. However, the ketonization potential of biomass-derived sugars and the mechanism underneath remain unclear. On this basis, a series of Fe doped CeO2 catalysts were synthesized and employed for catalytic ketonization of xylan. Characterization of the catalysts proved the successful formation of the Fe-CeOx solid solution. Doping an appropriate amount of Fe (20-33%) ions on CeO2 could obviously increase the number of oxygen vacancy and basic sites. During the catalytic reaction of xylan, pure CeO2 exhibited a great ketonization ability during xylan pyrolysis, and the introduction of a certain amount of Fe further enhanced the ability. Both the yield of ketones and the selectivity to linear ketones like acetone and 2-butanone reached the maximum for 33%Fe-CeOx. Thus, oxygen-rich compounds had been converted to low oxygen containing and high-quality ketone components. Introducing Fe into CeO2 favored the production of ethylene glycol rather than 2,3-dihydroxy propanal, and thus promoted the yield of acetone. This investigation provides fundamentals for the deoxygenation of biomass through catalytic ketonization, aiming at the production of value-added ketone products.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Reactive oxygen species (ROS) play a pivotal role in maintaining tissue homeostasis, yet their overabundance can impair normal cellular functions, induce cell death, and potentially lead to neurodegenerative disorders. This study identifies Drosophila Glycoprotein 93 (Gp93) as a crucial factor that safeguards tissue homeostasis and preserves normal neuronal functions by preventing ROS-induced, JNK-dependent apoptotic cell death. Firstly, loss of Gp93 induces JNK-dependent apoptosis primarily through the induction of ROS. Secondary, neuro-specific depletion of Gp93 results in ROS-JNK-mediated neurodegeneration. Thirdly, overexpression of Gp93 effectively curtails oxidative stress and neurodegeneration caused by paraquat exposure or the aging process. Furthermore, these functions of Gp93 can be substituted by its human ortholog, HSP90B1. Lastly, depletion of HSP90B1 in cultured human cells triggers ROS production, JNK activation, and apoptosis. Thus, this study not only unveils a novel physiological function of Gp93, but also provides valuable insights for understanding the physiological and pathological functions of human HSP90B1.
A 60-year-old man, with a history of surgery followed by chemoradiotherapy for cardiac cancer 5 years ago, was referred for backache and hematemesis. The abdominal computed tomography angiography (CTA) revealed a pseudoaneurysm of the descending thoracic aorta ([Fig. 1]). Emergency endovascular repair was performed during which contrast media extravasated outside the descending aorta and flowed into the esophagus ([Fig. 2]) before stent graft insertion. The endovascular intervention was successful, but bloody fluid was still drained from the stomach tube, together with hematochezia. A bedside gastroscopy was therefore arranged to detect ongoing or recurrent gastrointestinal bleeding.
See also: Efficacy of endoscopic ligation with O-ring closure for prevention of bleeding after gastric endoscopic submucosal dissection under antithrombotic therapy: a prospective observational studyEndoscopy 2022; 54(11): 1078-1084DOI: 10.1055/a-1782-3448 See also: Reply to Wu et al.Endoscopy 2022; 54(11): 1126-1126DOI: 10.1055/a-1904-8093
We observe experimentally, for the first time to our knowledge, a secondary plateau in UV-driven high harmonic generation in the X-ray regime, extending the conventional cutoff from 130 eV to 300 eV, due to emission of a single X-ray photon at double recombination of highly-correlated electrons in helium atoms. Intense 400 nm UV laser pulses, with a duration of 28 fs and energies of up to 2.8 mJ at 1 kHz, derived through a second harmonic upconversion of a Ti:Sapphire laser amplifier, are used to drive high harmonic generation inside a gas-filled hollow waveguide (Fig. 1A). Bright emission extending up to 120–150 eV from He, Ne, and Ar is observed within the effective phase-matching cutoffs for UV driving lasers, where low quantum diffusion of the rescattering electron and high linear refractive indices of atoms and ions contribute favorably to increase the single atom and ion yield, and the phase-matching efficiency [1]. Surprisingly, at laser intensities greater than $2.5\times 10^{15}$ W/cm 2 , the X-ray emission from He exhibits two signature plateau regions – a conventional combined plateau extending up to 130 eV from He atoms and He + ions, determined using TDSE calculations including two active electrons [2], as well as a secondary plateau extending - well beyond the conventional $3.2U_{p}$ cutoff - up to 300 eV (Fig. 1B, C, D), where $U_{p}$ is the ponderomotive energy. Numerical simulations predict that double-electron-recombination (DER) is the physical process of highest probability to yield a secondary plateau. In this highly-correlated electron system, fractions of the two electron wavefunctions are ionized at different laser half-cycles and travel along different trajectories, mitigating strong repulsion during local space-time correlation in the presence of the strong UV field, but recombine with the parent ion at the same instant to produce a single X-ray photon. The observed DER plateau in He is >4 orders of magnitude weaker, and has a characteristic stronger dependence on the ellipticity of the UV driver, due to the longer rescattering time (Fig. 1B). A laser intensity scan indicates that the DER cutoffs scale as $5.5U_{p}$ (Fig. 1C), in agreement with earlier theoretical scaling as $hv_{DER}={I_{p}}^{(1)}+{I_{p}}^{(2)}+5.5U_{p}$ or ${I_{p}}^{(1)}+{I_{p}}^{(2)}+4.7U_{p}$ for ionization of the two electrons separated by a full or a half-laser cycle [3], in contrast to the single-electron recombination (SER) - $hv_{SER}={I_{p}}^{(i)}+3.2U_{p}$ where ${I_{p}}^{(1)}=24.4\ \text{eV}$ and ${I_{p}}^{(2)}=54.6\ \text{eV}$ are the ionization potentials of He.
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