Evidence for Topological Magnon-Phonon Hybridization in a 2D Antiferromagnet down to the Monolayer Limit.

Topological phonons and magnons potentially enable low-loss, quantum coherent, and chiral transport of information and energy at the atomic scale. Van der Waals magnetic materials are promising to realize such states due to their recently discovered strong interactions among the electronic, spin, and lattice degrees of freedom. Here, we report the first observation of coherent hybridization of magnons and phonons in monolayer antiferromagnet FePSe3 by cavity-enhanced magneto-Raman spectroscopy. The robust magnon-phonon cooperativity in the 2D limit occurs even in zero magnetic field, which enables nontrivial band inversion between longitudinal and transverse optical phonons caused by the strong coupling with magnons. The spin and lattice symmetry theoretically guarantee magnetic-field-controlled topological phase transition, verified by nonzero Chern numbers calculated from the coupled spin-lattice model. The 2D topological magnon-phonon hybridization potentially offers a new route toward quantum phononics and magnonics with an ultrasmall footprint.

[Design of Remote Slit Lamp Diagnosis Platform Based on IoT Technology].

In order to realize the diagnosis of slit lamp in cross-regional patients and improve the real-time and convenience of diagnosis, a remote slit lamp diagnosis platform based on Internet of Things (IoT) technology is designed. Firstly, the feasibility of remote slit lamp is analyzed. Secondly, the IoT platform architecture of doctor/server/facility (D/S/F) is proposed and a remote slit lamp is designed. Finally, the performance of the remote slit lamp diagnostic platform is tested. The platform solves the communication problem of distributed slit lamps and realizes respectively numerical control of multi-area slit lamp by multi-eye experts. The test results show that the remote control delay of the platform is less than 20 ms, which supports multiple experts to diagnose multiple patients separately.

Photocatalyzed Defluorinative Dichloromethylation of α-CF3 Alkenes Using CHCl3 as the Radical Source.

A visible-light-induced defluorinative dichloromethylation of α-CF3 alkenes was developed with cheap and readily accessible chloroform simultaneously as a dichloromethylation reagent and reaction medium, leading to the facile preparation of new polyhalogenated scaffolds. Notably, the change from CHCl3 to CDCl3 offers a straightforward pathway for accessing the deuterated analogues with excellent degrees of D incorporation. Mechanistic studies suggested the reaction underwent a radical addition of the dichloromethyl radical with alkenes, followed by sequential single-electron transfer and defluorination. This protocol features mild conditions, easy operation, facile scalability, and high efficiency, allowing convenient access to dichloronated gem-difluoroalkenes.

Tunable layered-magnetism-assisted magneto-Raman effect in a two-dimensional magnet CrI3.

We used a combination of polarized Raman spectroscopy experiment and model magnetism-phonon coupling calculations to study the rich magneto-Raman effect in the two-dimensional (2D) magnet CrI3 We reveal a layered-magnetism-assisted phonon scattering mechanism below the magnetic onset temperature, whose Raman excitation breaks time-reversal symmetry, has an antisymmetric Raman tensor, and follows the magnetic phase transitions across critical magnetic fields, on top of the presence of the conventional phonon scattering with symmetric Raman tensors in N-layer CrI3 We resolve in data and by calculations that the first-order A g phonon of the monolayer splits into an N-fold multiplet in N-layer CrI3 due to the interlayer coupling [Formula: see text] and that the phonons within the multiplet show distinct magnetic field dependence because of their different layered-magnetism-phonon coupling. We further find that such a layered-magnetism-phonon coupled Raman scattering mechanism extends beyond first-order to higher-order multiphonon scattering processes. Our results on the magneto-Raman effect of the first-order phonons in the multiplet and the higher-order multiphonons in N-layer CrI3 demonstrate the rich and strong behavior of emergent magneto-optical effects in 2D magnets and underline the unique opportunities of spin-phonon physics in van der Waals layered magnets.

Photoinduced Construction of a Benzothienopyridine-S,S-dioxide Framework Enabled by Polychloropyridyl Multifunctional Motifs.

Reported herein is a visible-light-induced, catalyst-free intramolecular cyclization of 4-phenylsulfonyl-2,3,5,6-tetrachloropyridine, leading to rapid assembly of a series of unprecedented benzo[4,5]thieno[3,2-c]pyridine 5,5-dioxide scaffolds under mild conditions. The rational introduction of a perchloropyridin-4-yl module significantly facilitated this photoinduced process and offers a versatile platform for broad structural variation. Mechanistic studies revealed that a newly identified charge-transfer complex with carbonate is crucial to this photoinduced process.

[3 + 2] vs. [4 + 1] Annulation: revisiting mechanism studies on the phosphine-catalysed domino sequence of alkynoates and activated methylenes.

The mechanism of the phosphine-catalysed domino sequence of alkynoates and activated methylenes has been computationally studied. The computational results revealed that the [3 + 2] annulation sequence could be ruled out, due to a difficult Knoevenagel condensation of aromatic aldehydes and active methylenes. The reaction proceeds through a [4 + 1] annulation pathway, which involves a phosphine-catalysed MBH-type reaction followed by a [1,5]-proton shift and dehydration to afford vinyl phosphonium intermediates as four-carbon synthons in the annulation reaction. Then 1,3-dicarbonyls act as nucleophiles to attack vinyl phosphonium intermediates, subsequently leading to a stepwise [1,3]-proton shift and an intramolecular nucleophilic attack to close the five-member ring.

Electron-Phonon and Spin-Lattice Coupling in Atomically Thin Layers of MnBi2Te4.

MnBi2Te4 represents a new class of magnetic topological insulators in which novel quantum phases emerge at temperatures higher than those found in magnetically doped thin films. Here, we investigate how couplings between electron, spin, and lattice are manifested in the phonon spectra of few-septuple-layer thick MnBi2Te4. After categorizing phonon modes by their symmetries, we study the systematic changes in frequency, line width, and line shape of a spectrally isolated A1g mode. The electron-phonon coupling increases in thinner flakes as manifested in a broader phonon line width, which is likely due to changes of the electron density of states. In 4- and 5-septuple thick samples, the onset of magnetic order below the Néel temperature is concurrent with a transition to an insulating state. We observe signatures of a reduced electron-phonon scattering across this transition as reflected in the reduced Fano parameter. Finally, spin-lattice coupling is measured and modeled from temperature-dependent phonon frequency.

Glenoid bony morphology along long diameter is associated with the occurrence of recurrent anterior shoulder dislocation: a case-control study based on three-dimensional CT measurements.

PURPOSE: The purpose of our study is to compare the anatomic parameters of proximal humerus, glenoid, and glenohumeral joint between patients with recurrent anterior shoulder dislocation (RASD) and patients without RASD with the assistance of three-dimensional (3D) CT scans. METHODS: Sixty patients were included in the study and divided into group RASD and group control. 3D-CT models of shoulder joint for each included patient were reconstructed and multiple anatomic parameters were measured. RESULTS: There were no statistically significant differences between the two groups in morphological parameters of humerus and glenohumeral joints. Long diameter of glenoid was 3.50 ± 0.34 cm for patients in group RASD and 3.31 ± 0.32 cm in group control (p = 0.039). There was a statistically significant difference in the ratio of long to short diameter of glenoid (p < 0.001). Ratio of humeral head height to glenoid long diameter (Hhh/Gld) was 1.02 ± 0.07 in group RASD, significantly lower than 1.09 ± 0.08 in group control (p = 0.001). Longitudinal depth of glenoid was significantly higher in group RASD (p = 0.013). CONCLUSION: The glenoid morphology along long diameter is closely correlated with the stability of glenohumeral joint, including glenoid long diameter and glenoid longitudinal depth. It is especially noteworthy that the value of Hhh/Gld decreases in patients with RASD. The difference of Hhh/Gld between the two groups reminds us that the correlation of bony structure along long diameter between glenoid and humeral head plays an important role in RASD.

Photoredox-Catalyzed Deoxygenation of Hexafluoroacetone Hydrate Enables Hydroxypolyfluoroalkylation of Alkenes.

An unprecedented photoredox-catalyzed phosphine-mediated deoxygenation of hexafluoroacetone hydrate was established to accomplish the hydroxylpolyfluoroalkylation of electron-deficient alkenes. A range of bis(trifluoromethyl)carbinols were facilely accessed by using readily available hexafluoroacetone hydrate, instead of toxic gaseous hexafluoroacetone. A range of electron-deficient alkenes are tolerated, giving the corresponding hydro-hydroxylpolyfluoroalkylated products in moderate to high yields. Remarkable features of this synthetic strategy include operational simplicity, mild reaction conditions, excellent regioselectivity, and broad functional group tolerance. The success of this strategy relies on the delicate utilization of aldehyde/ketone-gem-diol intrinsic equilibrium, which offers an innovated open-shell pathway for the assembly of synthetically challenging polyfluoroalkylated scaffolds.

Regioselective Access to Vicinal Diamines by Metal-Free Photosensitized Amidylimination of Alkenes with Oxime Esters.

A metal-free photosensitized protocol for regioselective diamination of alkene feedstocks over a single step was developed based on the rationally designed bifunctional diamination reagent, thus affording a range of differentially protected 1,2-diamines in moderate to high yields. Mechanistic studies reveal that the reaction is initiated with a triplet-triplet energy transfer between thioxanthone catalyst and diamination reagent, followed by fragmentation to simultaneously generate long-lived iminyl radical and transient amidyl radical. The excellent regioselectivity presumably stems from the large reactivity difference between two different N-centered radical species. This protocol is characterized by excellent regioselectivity, broad functional group tolerance, and mild reaction conditions, which would enrich the diversity and versatility of facilitate the diversity-oriented synthesis of 1,2-diamine-containing complex molecule scaffolds.

N,N,N',N'-Tetramethylethylenediamine-Enabled Photoredox-Catalyzed C-H Methylation of N-Heteroarenes.

Aiming at the valuable methylation process, readily available and inexpensive N,N,N',N'-tetramethylethylenediamine (TMEDA) was first identified as a new methyl source in photoredox-catalyzed transformation in this work. By virtue of this simple methylating reagent, a facile and practical protocol for the direct C-H methylation of N-heteroarenes was developed, featuring mild reaction conditions, broad substrate scope, and scalability. Mechanistic studies disclosed that a sequential photoredox, base-assisted proton shift, fragmentation, and tautomerization process was essentially involved.

Visible Light-Promoted Radical Relay Cyclization/C-C Bond Formation of N-Allylbromodifluoroacetamides with Quinoxalin-2(1H)-ones.

A visible light-promoted radical relay of N-allylbromodifluoroacetamide with quinoxalin-2(1H)-ones was developed in which 5-exo-trig cyclization and C-C bond formation were involved. This protocol was performed under mild conditions to facilely offer a variety of hybrid molecules bearing both quinoxalin-2(1H)-one and 3,3-difluoro-γ-lactam motifs. These prepared novel skeletons would expand the accessible chemical space for structurally complex heterocycles with potential biological activities.

Visible-Light-Driven, Photocatalyst-Free Cascade to Access 3-Cyanoalkyl Coumarins from ortho-Hydroxycinnamic Esters.

A visible-light-driven, photocatalyst-free route starting from easily accessed ortho-hydroxycinnamic esters and O-perfluoropyridin-4-yl oximes has been successfully developed to rapidly assemble a wide range of 3-cyanoalkyl coumarins. This process does not require addition of external photocatalysts, exhibiting beneficial features including mild reaction conditions, synthetic simplicity, and excellent substrate compatibility. Extensive mechanistic investigations revealed that the in situ generated phenolate anions served as photosensitizers to drive this photoinduced transformation.

Intercalary prosthetic replacement is a reliable solution for metastatic humeral shaft fractures: retrospective, observational study of a single center series.

BACKGROUND: Treatments for metastatic fracture of the humeral shaft continue to evolve as advances are made in both oncological and operative management. The purposes of this study were to critically evaluate the effectiveness of intercalary endoprostheses in treating metastatic humeral shaft fractures and to clarify the surgical indications for this technique. METHODS: Sixty-three patients treated surgically for 66 metastatic fractures of the humerus shaft were retrospectively reviewed. Intramedullary nailing (IMN) was performed in 16 lesions, plate fixation (PF) in 33 lesions, and prosthetic replacement in 17 lesions. The operative time, intraoperative blood loss, and postoperative complications were noted. The function of the upper extremities was assessed by the Musculoskeletal Tumor Society (MSTS) score and American Shoulder and Elbow Surgeons (ASES) score. All included patients were followed until reconstructive failure or death. RESULTS: The operative time was relatively shorter in the prosthesis group than in either the IMN group (p = 0.169) or PF group (p = 0.002). Notably, intraoperative blood loss was significantly less in the prosthesis group than in either the IMN group (p = 0.03) or PF group (p = 0.012). The average follow-up time was 20.3 (range, 3-75) months, and the overall survival rate was 59.7% at 12 months and 46.7% at 24 months. One rotator cuff injury, 3 cases of iatrogenic radial nerve palsy, 5 cases of local tumor progression, and 1 mechanical failure occurred in the osteosynthesis group, whereas one case of aseptic loosening of the distal stem and one case of local relapse were observed in the prosthesis group. There were no significant differences in functional scores among the three groups. CONCLUSIONS: Intercalary prosthetic replacement of the humeral shaft may be a reliable solution for pathologic fractures patients; it is indicated for lesions with substantial bone loss, or accompanied soft tissue mass, or for those patients with better prognosis.

Arthroscopic evaluation for tibial plateau fractures on the incidence and types of cruciate ligamentous injuries following closed reduction and internal fixation.

PURPOSE: To evaluate the overall incidence and types of anterior cruciate ligament (ACL) injuries and posterior cruciate ligament (PCL) injuries associated with tibial plateau fractures (TPFs) following closed reduction and internal fixation (CRIF), and to identify the relationship between the incidence and types of cruciate ligamentous injuries with Schatzker classification and "three-column" classification. METHODS: From January 2016 to January 2018, 185 patients with closed TPFs who underwent CRIF were included in this retrospective study. All patients were performed with arthroscopic examination after CRIF, and then, the incidence and types of cruciate ligamentous injuries were recorded and evaluated. RESULTS: The overall incidence rates of cruciate ligamentous injuries associated with TPFs were 37.3% with 21.6% of these being ACL injuries and 15.7% had PCL injuries. Importantly, patients with fractures in "two-column" fractures have a significantly higher incidence rate of ACL avulsion fracture and PCL complete tears (P < 0.05) than other fracture types, especially involving anteromedial and posterior column fractures. In addition, the incidence of PCL partial tears in patients with three-column involvement was 11.8%, which was higher than other fracture patterns based on three-column classification system (P < 0.05). In the current study, Schatzker IV was most commonly associated with ACL injuries, occurring in 48.1% of our series. Furthermore, PCL injuries occurred at a significantly higher incidence in Schatzker VI with 34.5% than other fracture types (P < 0.05). Statistical analysis revealed that there was a significant difference between Schatzker classification and incidence of injury to the ACL (P < 0.05) and PCL (P < 0.05). Of note, avulsion fracture was the most common types of ACL injuries which was observed in 45% ACL injuries, while partial tear was the most common types of PCL injuries. However, no significant relationship was identified between the types of cruciate ligamentous injuries and Schatzker classification (P > 0.05). CONCLUSIONS: In the recognition of concomitant cruciate ligamentous injuries associated with TPFs based on Schatzker classification and three-column classification, orthopaedic trauma surgeons may better guide optimal surgical protocols for patients.

Changes in patellar height and posterior tibial slope angle following uniplanar medial opening wedge high tibial osteotomy using a novel wedge-shaped spacer implanation concurrent with proximal partial fibulectomy.

PURPOSE: The purpose of this study was to evaluate changes of patellar height and posterior tibial slope angle following uniplanar medial opening wedge high tibial osteotomy using a novel wedge-shaped spacer implanation concurrent with proximal partial fibulectomy. METHODS: All patients who underwent uniplanar medial opening wedge high tibial osteotomy using a novel wedge-shaped spacer implanation concurrent with proximal partial fibulectomy between January 2017 and February 2019 were included and assessed retrospectively. Radiological assessment was made in terms of the changes in patellar height and posterior tibial slope angle between pre-operative and post-operative radiographs. RESULTS: Thirty-five patients (9 males and 26 females) with a mean age of 57.3 years (range 50.8-64.2 years) were enrolled in this study protocol and demonstrated decreased posterior tibial slope angle post-operatively (9.7° ± 2.5° pre-operatively and 7.3° ± 1.8° post-operatively, P < 0.001). Patellar height was unchanged significantly post-operatively (Caton-Deschamps: 0.83 ± 0.12 pre-operatively and 0.82 ± 0.09 post-operatively, P > 0.05). CONCLUSIONS: Uniplanar medial opening wedge high tibial osteotomy using a novel wedge-shaped spacer implanation concurrent with proximal partial fibulectomy can decrease posterior tibial slope and maintain the patellar height.

Long-term outcomes after partial patellectomy in comminuted fractures - a clinical study.

PURPOSE: The purpose of this study was to evaluate the long-term clinical and radiographic outcomes of partial patellectomy (PP) in patients with patella comminuted distal pole fractures. METHODS: Seventeen patients who were diagnosed with patella comminuted distal pole fractures and underwent PP procedures were retrospectively included between January 1995 and January 2005. We collected patient demographics and data on the mechanism of injury, time to surgery, fracture type, follow-up time, and post-operative complications (infection, patellofemoral arthritis, and stiffness). At the final follow-up, functional outcome was evaluated by the range of motion (ROM) and the Bostman Scoring System. Quadriceps strength was evaluated by using an isokinetic dynamometer to measure peak torque, and patellar height was evaluated by the Insall-Salvati (IS) ratio in lateral knee radiographs. The average follow-up period was 14.6 years (range, 11-19 years). RESULTS: We analyzed 17 patients (AO/OTA 34-A1), with an average age of 59.8 years (range, 43-76 years). According to the Bostman grading scales, final functional outcomes were excellent in 11 (64.7%) and good in six (35.3%) patients. All patients had full knee extension, and the average ROM was 125.1° (range, 121.4-129.3°). The average peak torque of the injured knee was 103.2 ± 9.7 Nm, and that of the uninjured opposite side was 108.3 ± 7.6 Nm, with no significant difference (p > 0.05). Furthermore, no postoperative complications, such as infection, posttraumatic osteoarthritis, or stiffness, were observed. Compared to the uninjured knee, the IS ratio of the injured knee was 0.76 ± 0.13, indicating that the patellar height was decreased, which meant patella baja. CONCLUSIONS: The PP procedure for patella comminuted distal pole fractures is a safe, simple, and reliable technique that can provide good long-term clinical outcomes even with decreased patellar height and could be a satisfactory alternative treatment option when anatomical reduction is difficult.

O-Perfluoropyridin-4-yl Oximes: Iminyl Radical Precursors for Photo- or Thermal-Induced N-O Cleavage in C(sp2)-C(sp3) Bond Formation.

O-Perfluoropyridin-4-yl group was first installed onto cycloketone oximes as a new electrophore, which was proven to be efficient iminyl radical precursors under photocatalytic and thermal conditions. A range of O-perfluoropyridin-4-yl oximes were successfully utilized in C(sp2)-C(sp3) bond formations of quinoxalin-2(1H)-ones and alkenes, providing facile accesses to a range of functionalized alkylnitriles.

Visible-Light-Induced, Catalyst-Free Radical Cross-Coupling Cyclization of N-Allylbromodifluoroacetamides with Disulfides or Diselenides.

A visible-light-induced, catalyst-free radical cross-coupling cyclization of diselenides or disulfides with N-allylbromodifluoroacetamide has been developed. This developed protocol exhibits good functional group tolerance and affords a variety of 4-thio- and 4-seleno-substituted 3,3-difluoro-γ-lactams in moderate to good yields. Based on control experiments, a plausible radical-radical cross-coupling pathway is proposed.

Photoinduced Single-Electron Transfer as an Enabling Principle in the Radical Borylation of Alkenes with NHC-Borane.

A photoinduced SET process enables the direct B-H bond activation of NHC-boranes. In contrast to common hydrogen atom transfer (HAT) strategies, this photoinduced reaction simply takes advantage of the beneficial redox potentials of NHC-boranes, thus obviating the need for extra radical initiators. The resulting NHC-boryl radical was used for the borylation of a wide range of α-trifluoromethylalkenes and alkenes with diverse electronic and structural features, providing facile access to highly functionalized borylated molecules. Labeling and photoquenching experiments provide insight into the mechanism of this photoinduced SET pathway.