Growth of Mesoscale Ordered Two-Dimensional Hydrogen-Bond Organic Framework with the Observation of Flat Band.

Flat bands (FBs), presenting a strongly interacting quantum system, have drawn increasing interest recently. However, experimental growth and synthesis of FB materials have been challenging and have remained elusive for the ideal form of monolayer materials where the FB arises from destructive quantum interference as predicted in 2D lattice models. Here, we report surface growth of a self-assembled monolayer of 2D hydrogen-bond (H-bond) organic frameworks (HOFs) of 1,3,5-tris(4-hydroxyphenyl)benzene (THPB) on Au(111) substrate and the observation of FB. High-resolution scanning tunneling microscopy or spectroscopy shows mesoscale, highly ordered, and uniform THPB HOF domains, while angle-resolved photoemission spectroscopy highlights a FB over the whole Brillouin zone. Density-functional-theory calculations and analyses reveal that the observed topological FB arises from a hidden electronic breathing-kagome lattice without atomically breathing bonds. Our findings demonstrate that self-assembly of HOFs provides a viable approach for synthesis of 2D organic topological materials, paving the way to explore many-body quantum states of topological FBs.

Effect of Graphene on the Performance of Silicon-Carbon Composite Anode Materials for Lithium-Ion Batteries.

(Si/graphite)@C and (Si/graphite/graphene)@C were synthesized by coating asphalt-cracked carbon on the surface of a Si-based precursor by spray drying, followed by heat treatment at 1000 °C under vacuum for 2h. The impact of graphene on the performance of silicon-carbon composite-based anode materials for lithium-ion batteries (LIBs) was investigated. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) images of (Si/graphite/graphene)@C showed that the nano-Si and graphene particles were dispersed on the surface of graphite, and thermogravimetric analysis (TGA) curves indicated that the content of silicon in the (Si/graphite/graphene)@C was 18.91%. More bituminous cracking carbon formed on the surface of the (Si/graphite/graphene)@C due to the large specific surface area of graphene. (Si/Graphite/Graphene)@C delivered first discharge and charge capacities of 860.4 and 782.1 mAh/g, respectively, initial coulombic efficiency (ICE) of 90.9%, and capacity retention of 74.5% after 200 cycles. The addition of graphene effectively improved the cycling performance of the Si-based anode materials, which can be attributed to the reduction of electrochemical polarization due to the good structural stability and high conductivity of graphene.

Band splitting and enhanced charge density wave modulation in Mn-implanted CsV3Sb5.

Kagome metal CsV3Sb5 has attracted unprecedented attention due to the charge density wave (CDW), Z2 topological surface states and unconventional superconductivity. However, how the paramagnetic bulk CsV3Sb5 interacts with magnetic doping is rarely explored. Here we report a Mn-doped CsV3Sb5 single crystal successfully achieved by ion implantation, which exhibits obvious band splitting and enhanced CDW modulation via angle-resolved photoemission spectroscopy (ARPES). The band splitting is anisotropic and occurs in the entire Brillouin region. We observed a Dirac cone gap at the K point but it closed at 135 K ± 5 K, much higher than the bulk value of ∼94 K, suggesting enhanced CDW modulation. According to the facts of the transferred spectral weight to the Fermi level and weak antiferromagnetic order at low temperature, we ascribe the enhanced CDW to the polariton excitation and Kondo shielding effect. Our study not only offers a simple method to realize deep doping in bulk materials, but also provides an ideal platform to explore the coupling between exotic quantum states in CsV3Sb5.

[Free perforator flap transfer to reconstruct the defect resulted from resection of head and neck tumor].

OBJECTIVE: To explore the method of free perforator flap reconstructing the defect resulted from head and neck tumor resection. METHOD: Twelve cases treated in our department because of head and neck tumor were reviewed, among which 3 cases employed rectus abdominis flap, 5 cases anterolateral thigh flap, 2 cases latissimus dorsi flap, 2 cases pectoris major flap. RESULT: One case failure with the transfer of latissimus dorsi flap, one case of partial necrosis of anterolateral thigh flap resulting in pharyngeal fistula, one case of artery thrombosis and one case of venous thrombosis occurred and the flap revived after emergent exploration and re-anastomosis. The total survival rate of the transferred flap is 91.6%. CONCLUSION: Free perforator flap is able to be a good choice to reconstruct big defect resulted from head and neck tumor resection because of its simple preparation, big size of donor site.

[Primary clinical outcome of the tongue mobility via deep cervical nerve or accessory nerve-restored sublingual nerve].

OBJECTIVE: To explore the clinical prognosis of sublingual nerve anastomosis with a branch of the deep cervical nerves or accessory nerve. METHOD: To retrospectively analyze 2 cases of paraganglion tumor,in which the sublingual nerve were disconnected because of overdrawing of surrounding tissue and tumor invasion. One branch of deep cervical nerve or accessory nerve was dissected and anastomosed to the distal end of sublingual nerve. Steroids and nerve nutritional chemicals were given after operation, and early functional physical exercise was recommended for the two patients. RESULT: The lingual mobility of the two patients was restored partially 1 to 2 months after operation, while the tongue of lesion side suffered from slight atrophy especially in the posterior 1/2 part. The patients experienced better and better mobility of the tongue. CONCLUSION: Sublingual nerve anastomosis with a branch of the deep cervical nerves or accessory nerve is viable. It could be a reconstructive modality for patients suffered from sublingual nerve disconnected.

[Modified pedicled cranial periosteum compound flap to reconstruct the defect of anterior cranial fossa complicated with cerebrospinal fluid leakage].

OBJECTIVE: To explore the effect of modified pedicled cranial periosteum compound flap in reconstructing the defect of anterior cranial fossa complicated with cerebrospinal fluid leakage. METHOD: Seven nasal and sinus tumor cases with defects and CSF were undertaken reconstructing surgery with the flap, of which 1 was benign and the others were malignancies. The transferred flap pedicled with the frontal branch of the superficial temporal artery and complemented with ipsilateral supraorbital and/or supratraochlear artery. RESULT: All cases healed without failure, one case with adjuvant radiotherapy experienced partial free frontal bone necrosis and healed by ways of drainage through temporal incision. The inner surface of the flap in the nasal cavity was smooth. CONCLUSION: Frontal cranial periosteum compound flap have some advantages, such as adequate quantity, good blood supply and easily making,so it can be choose as an important method to reconstruct the defects of anterior cranial fossa and CSF leakage.