Construction of Benzoxazine-linked One-Dimensional Covalent Organic Frameworks Using the Mannich Reaction.

Covalent polymerization of organic molecules into crystalline one-dimensional (1D) polymers is effective for achieving desired thermal, optical, and electrical properties, yet it remains a persistent synthetic challenge for their inherent tendency to adopt amorphous or semicrystalline phases. Here we report a strategy to synthesize crystalline 1D covalent organic frameworks (COFs) composing quasi-conjugated chains with benzoxazine linkages via the one-pot Mannich reaction. Through [4+2] and [2+2] type Mannich condensation reactions, we fabricated stoichiometric and sub-stoichiometric 1D covalent polymeric chains, respectively, using doubly and singly linked benzoxazine rings. The validity of their crystal structures has been directly visualized through state-of-the-art cryogenic low-dose electron microscopy techniques. Post-synthetic functionalizations of them with a chiral MacMillan catalyst produce crystalline organic photocatalysts that demonstrated excellent catalytic and recyclable performance in light-driven asymmetric alkylation of aldehydes, affording up to 94 % enantiomeric excess.

Three-Dimensional Crystalline Organic Framework Stabilized by Molecular Mortise-and-Tenon Jointing.

Three-dimensional (3D) crystalline organic frameworks with complex topologies, high surface area, and low densities afford a variety of application prospects. However, the design and construction of these frameworks have been largely limited to systems containing polyhedron-shaped building blocks or those relying on component interpenetration. Here, we report the synthesis of a 3D crystalline organic framework based on molecular mortise-and-tenon jointing. This new material takes advantage of tetra(4-pyridylphenyl)ethylene and chlorinated bis(benzodioxaborole)benzene as building blocks and is driven by dative B-N bonds. A single-crystal X-ray diffraction analysis of the framework reveals the presence of two-dimensional (2D) layers with helical channels that are formed presumably during the boron-nitrogen coordination process. The protrusion of dichlorobenzene units from the upper and lower surfaces of the 2D layers facilitates the key mortise-and-tenon connections. These connections enable the interlocking of adjacent layers and the stabilization of an overall 3D framework. The resulting framework is endowed with high porosity and attractive mechanical properties, rendering it potentially suitable for the removal of impurities from acetylene.

A metal-free photoactive nitrogen-doped carbon nanosolenoid with broad absorption in visible region for efficient photocatalysis.

Riemann surfaces inspired chemists to design and synthesize such multidimensional curved carbon architectures. It has been predicted that carbon nanosolenoid materials with Riemann surfaces have unique structures and novel physical properties. Here we report the first synthesis of a nitrogen-doped carbon nanosolenoid (N-CNS) using bottom-up approach with a well-defined structure. N-CNS was obtained by a rational Suzuki polymerization, followed by oxidative cyclodehydrogenation. The successful synthesis of N-CNS was fully characterized by GPC, FTIR, solid-state 13C NMR and Raman techniques. The intrinsic single-strand molecular structures of N-CNS helices can be clearly resolved using low-dose integrated differential phase contrast scanning transmission electron microscopy (iDPC-STEM) technique. Possessing unique structural and physical properties, this long π-extended polymer N-CNS can provide new insight towards bottom-up syntheses of curved nanoribbons and potential applications as a metal-free photocatalyst for visible-light-driven H2 evolution and highly efficient photocatalyst for photoredox organic transformations.

Formation of polyrotaxane crystals driven by dative boron-nitrogen bonds.

The integration of mechanically interlocked molecules (MIMs) into purely organic crystalline materials is expected to produce materials with properties that are not accessible using more classic approaches. To date, this integration has proved elusive. We present a dative boron-nitrogen bond-driven self-assembly strategy that allows for the preparation of polyrotaxane crystals. The polyrotaxane nature of the crystalline material was confirmed by both single-crystal x-ray diffraction analysis and cryogenic high-resolution low-dose transmission electron microscopy. Enhanced softness and greater elasticity are seen for the polyrotaxane crystals than for nonrotaxane polymer controls. This finding is rationalized in terms of the synergetic microscopic motion of the rotaxane subunits. The present work thus highlights the benefits of integrating MIMs into crystalline materials.

H+ -H- Pairs in Partially Oxidized MAX Phases for Bifunctional Catalytic Conversion of Furfurals into Linear Ketones.

Currently, less favorable C=O hydrogenation and weak concerted acid catalysis cause unsatisfactory catalytic performance in the upgrading of biomass-derived furfurals (i.e., furfural, 5-methyl furfural, and 5-hydroxymethyl furfural) to ketones (i.e., cyclopentanone, 2,5-hexanedione, and 1-hydroxyl-2,5-hexanedione). A series of partially oxidized MAX phase (i.e., Ti3 AlC2 , Ti2 AlC, Ti3 SiC2 ) supporting Pd catalysts were fabricated, which showed high catalytic activity; Pd/Ti3 AlC2 in particular displayed high performance for conversion of furfurals into targeted ketones. Detailed studies of the catalytic mechanism confirm that in situ hydrogen spillover generates Frustrated Lewis H+ -H- pairs, which not only act as the hydrogenation sites for selective C=O hydrogenation but also provide acid sites for ring opening. The close intimate hydrogenation and acid sites promote bifunctional catalytic reactions, substantially reducing the reported minimum reaction temperature of various furfurals by at least 30-60 °C.

Analysis of influencing factors on post-treatment in-stent stenosis of intracranial aneurysm using Pipeline embolization device / 中华放射学杂志

Objective:To evaluate the incidence, clinical significance and influencing factors on in-stent stenosis(ISS) after treatment of intracranial aneurysms by Pipeline embolization device(PED).Methods:A retrospective analysis was conducted on the clinical data of 161 patients with intracranial aneurysms treated with PED at the Department of Interventional Radiology of the First Affiliated Hospital of Zhengzhou University from April 2015 to July 2021. PED was implanted into the parent artery through the femoral artery approach after general anesthesia. The first DSA follow-up duration time and imaging data were collected, and the patients were divided into ISS group and non-ISS group accordingly. The degree of aneurysm occlusion was evaluated by O′Kelly-Marotta(OKM) grading scale. Univariate and multivariate logistic regression analysis were applied to identify the factors related to ISS.Results:A total of 179 PED were employed in 161 patients with 168 aneurysms. Eighty-eight (52.38%) aneurysms were treated by PED only, and 80 (47.62%) aneurysms by PED combined with coiling. After a median follow-up of 6 (5, 7) months, 31(18.45%) aneurysms had ISS within the PED, of which 16(9.52%) cases were with mild stenosis (<50%), 13 (7.74%) were with moderate stenosis (50%-75%), and 2(1.19%) were with severe stenosis (>75%). All patients with ISS showed no relevant clinical symptoms. One (0.60%) patient with ISS underwent balloon angioplasty. Univariate analysis showed that the stent diameter, aneurysm location, triglyceride level, the diameter of distal parent artery, and the diameter of proximal parent artery were associated to ISS. Further multivariate logistic regression analysis showed the stent diameter (OR=0.332, 95%CI 0.191-0.578, P<0.001) and triglyceride level (OR=1.641, 95%CI 1.034-2.605, P=0.036) were independent factors of ISS. Conclusions:ISS is a common benign complication after PED treatment. The current results suggest that small stent diameter and high triglyceride level are independent factors of ISS.

Clinical application of excimer laser ablation in lower extremity arterial ischemic diseases / 国际外科学杂志

Objective:To evaluate the therapeutic effect of excimer laser ablation (ELA) in the treatment of lower extremity arterial ischemic diseases.Methods:The clinical data of 44 patients with lower extremity ischemic diseases treated with ELA in the People′s Hospital of Xinjiang Uygur Autonomous Region from December 2020 to April 2021 were analyzed retrospectively. Among the 44 patients, there were 29 patients in lower extremity arteriosclerosis obliterans (ASO), including 3 patients with femoral artery stent occlusion. 8 patients of diabetes foot (DF) and 7 patients of thromboangiitis obliterans (TAO). Observation indicators include target vascular patency rate, amputation rate, vascular reintervention rate and mortality rate. The measurement data were expressed as mean ± standard deviation ( ± s), one-way analysis of variance was used for inter-group comparison, and paired sample t-test was used for intra-group comparison. The Chi-square test was used for comparison between count data. Results:The success rate of operation was 100% in 44 patients. The rate of major amputation in ASO group was 10.3%, while the other two groups had a major amputation rate of 0. The minor amputation rates of the three groups were 6.9%, 25.0% and 28.6%, respectively. The vascular reintervention rate was 10.3% in ASO group, 12.5% in DF group and 0 in TAO group. The 1-year mortality rate in the ASO group was 10.3%, while the other two groups had a mortality rate of 0. The 2-year mortality rate of the three group were 31.0%, 12.5% and 0, respectively.Conclusion:For the treatment of lower extremity arterial ischemic diseases, ELA is safe and effective, but the curative effect need to further clarify by large sample and long-term clinical follow-up observation.

Effect of High-Concentration Uric Acid on Nitric Oxide / 中国医学科学院学报

Uric acid (UA) is the final product of purine metabolism in human body,and its metabolic disorder will induce hyperuricemia (HUA).The occurrence and development of HUA are associated with a variety of pathological mechanisms such as oxidative stress injury,activation of inflammatory cytokines,and activation of renin-angiotensin-aldosterone system.These mechanisms directly or indirectly affect the bioavailability of endogenous nitric oxide (NO).The decrease in NO bioavailability is common in the diseases with high concentration of UA as an independent risk factor.In this review,we summarize the mechanisms by which high concentrations of UA affect the endogenous NO bioavailability,with a focus on the mechanisms of high-concentration UA in decreasing the synthesis and/or increasing the consumption of NO.This review aims to provide references for alleviating the multisystem symptoms and improving the prognosis of HUA,and lay a theoretical foundation for in-depth study of the correlations between HUA and other metabolic diseases.

Preliminary exploration of endovascular treatment for cerebral infarction caused by middle cerebral artery stenosis with hypoperfusion in the blood supply area of the lenticulostriate artery / 中华神经科杂志

Objective:To evaluate the necessity, safety and efficacy of endovascular treatment for cerebral infarction caused by middle cerebral artery (MCA) stenosis with hypoperfusion in the blood supply area of the lenticulostriate artery.Methods:The clinical and surgical data of patients with MCA atherosclerotic disease who underwent endovascular treatment in the First Affiliated Hospital of Zhengzhou University from January 2014 to October 2021 were retrospectively analyzed. A total of 6 patients with cerebral infarction caused by MCA stenosis with hypoperfusion in the blood supply area of the lenticulostriate artery were selected. The preoperative and postoperative clinical imaging characteristics, perioperative complications and follow-up of these 6 patients were summarized and evaluated.Results:After the endovascular treatment, the imaging of the lenticulostriate artery in all the 6 patients was clearer than that before the operation, and the number of main trunks of the lenticulostriate artery shown by imaging in 2 patients was more than that before operation. The computer tomography perfusion of 6 patients after the endovascular treatment showed that perfusion in the supply area of the lenticulostriate artery was significantly improved compared with pre-operation. No stroke, transient ischemic attack (TIA) and death occurred during the perioperative period. The time of clinical follow-up was 360 (322, 495) days, and there were no stroke, TIA or death occurring in the corresponding artery. All the 6 patients underwent imaging follow-up, of which 3 patients underwent digital subtraction angiography and 3 underwent CT angiography. The lumen of the target vessels showed patency in all patients.Conclusions:With rigorous imaging evaluation, endovascular treatment may be safe and effective for cerebral infarction caused by MCA stenosis with hypoperfusion in the blood supply area of the lenticulostriate artery.

Chemical Transformation Induced Core-Shell Ni2P@Fe2P Heterostructures toward Efficient Electrocatalytic Oxygen Evolution.

The oxygen evolution reaction (OER) is a crucial reaction in water splitting, metal-air batteries, and other electrochemical conversion technologies. Rationally designed catalysts with rich active sites and high intrinsic activity have been considered as a hopeful strategy to address the sluggish kinetics for OER. However, constructing such active sites in non-noble catalysts still faces grand challenges. To this end, we fabricate a Ni2P@Fe2P core-shell structure with outperforming performance toward OER via chemical transformation of rationally designed Ni-MOF hybrid nanosheets. Specifically, the Ni-MOF nanosheets and their supported Fe-based nanomaterials were in situ transformed into porous Ni2P@Fe2P core-shell nanosheets composed of Ni2P and Fe2P nanodomains in homogenous dispersion via a phosphorization process. When employed as the OER electrocatalyst, the Ni2P@Fe2P core-shell nanosheets exhibits excellent OER performance, with a low overpotential of 238/247 mV to drive 50/100 mA cm-2, a small Tafel slope of 32.91 mV dec-1, as well as outstanding durability, which could be mainly ascribed to the strong electronic interaction between Ni2P and Fe2P nanodomains stabilizing more Ni and Fe atoms with higher valence. These high-valence metal sites promote the generation of high-active Ni/FeOOH to enhance OER activity.

Construction of Core-Shell CoMoO4@γ-FeOOH Nanosheets for Efficient Oxygen Evolution Reaction.

The oxygen evolution reaction (OER) occurs at the anode in numerous electrochemical reactions and plays an important role due to the nature of proton-coupled electron transfer. However, the high voltage requirement and low stability of the OER dramatically limits the total energy converting efficiency. Recently, electrocatalysts based on multi-metal oxyhydroxides have been reported as excellent substitutes for commercial noble metal catalysts due to their outstanding OER activities. However, normal synthesis routes lead to either the encapsulation of excessively active sites or aggregation during the electrolysis. To this end, we design a novel core-shell structure integrating CoMoO4 as support frameworks covered with two-dimensional γ-FeOOH nanosheets on the surface. By involving CoMoO4, the electrochemically active surface area is significantly enhanced. Additionally, Co atoms immerge into the γ-FeOOH nanosheet, tuning its electronic structure and providing additional active sites. More importantly, the catalysts exhibit excellent OER catalytic performance, reducing overpotentials to merely 243.1 mV a versus 10 mA cm-2. The current strategy contributes to advancing the frontiers of new types of OER electrocatalysts by applying a proper support as a multi-functional platform.

Precursor Customized Assembly of Wafer-Scale Polymerized Aniline Thin Films for Ultrasensitive NH3 Detection.

2D conducting polymer thin film recently has garnered numerous interests as a means of combining the molecular aggregate ordering and promoting in-plane charge transport for large-scale/flexible organic electronics. However, it remains far from satisfactory for conducting polymer chains to achieve desirable surface topography and crystallinity due to lack of control over the precursor-involved interfacial assembly. Herein, wafer-size polyaniline (PANI) and tetra-aniline thin films are developed via a controlled interfacial synthesis with customized surface morphology and crystallinity through two typical aniline precursors selective polymerization. Two crucial competing assembly mechanisms, a) direct interfacial polymerization, b) solution polymerization and subsequent interfacial assembly, are investigated to play a vital role in determining elemental chain length and aggregate architecture. The optimal PANI thin film manifests ultraflat surface topography and unambiguous crystalline domains, which also enabling fascinating ammonia sensing capability with 31.4% ppm-1 sensitivity, fast response time (88 s) with astonishing selectivity, repeatability, and recovery capability. The thus-demonstrated strategy with wafer-scale processing potential and flexible microdevice offers a promising route for large-scale manufacturing thin-film organic electronics.

Synthesis and Visualization of Entangled 3D Covalent Organic Frameworks with High-Valency Stereoscopic Molecular Nodes for Gas Separation.

The structural diversity of three-dimensional (3D) covalent organic frameworks (COFs) are limited as there are only a few choices of building units with multiple symmetrically distributed connection sites. To date, 4 and 6-connected stereoscopic nodes with Td , D3h , D3d and C3 symmetries have been mostly reported, delivering limited 3D topologies. We propose an efficient approach to expand the 3D COF repertoire by introducing a high-valency quadrangular prism (D4h ) stereoscopic node with a connectivity of eight, based on which two isoreticular 3D imine-linked COFs can be created. Low-dose electron microscopy allows the direct visualization of their 2-fold interpenetrated bcu networks. These 3D COFs are endowed with unique pore architectures and strong molecular binding sites, and exhibit excellent performance in separating C2 H2 /CO2 and C2 H2 /CH4 gas pairs. The introduction of high-valency stereoscopic nodes would lead to an outburst of new topologies for 3D COFs.

Engineering the degree of concavity of one-dimensional Au-Cu alloy nanorods with partial intermetallic compounds by facile wet chemical synthesis.

Finely modulating the morphology of bimetallic nanomaterials plays a vital role in enhancing their catalytic activities. Among the various morphologies, concave structures have received considerable attention due to the three advantageous features of high-index facets, high surface areas, and high curvatures, which contribute greatly to enhancing the catalytic performance. However, concave morphologies are not the products generated from thermodynamically controlled growth with minimized surface energy. Additionally, most nanocrystals with concave shapes are currently in the state of mono-metals or alloys with disordered arrangements of atoms. The synthesis of alloy structures with ordered atom arrangements, intermetallic compounds, which tend to display superior catalytic performance on account of their optimal geometric and electronic effects, has rarely been reported as high-temperature annealing is usually needed, which constrains the modulation of morphology and surface structure. In this work, concave one-dimensional Au-Cu nanorods with a partially ordered intermetallic structure were synthesized via a facile wet chemical method. By simply adjusting the reaction kinetics via the concentrations of the corresponding metal precursors, the degree of concavity of the one-dimensional Au-Cu nanorods could be regulated. In both the p-nitrophenol reduction and CO2 electro-reduction reactions, the concave-shaped Au-Cu nanorods demonstrated superior catalytic activity compared to corresponding non-concave samples with the same structure due to the morphological advantages provided by the concave structure.

Isoreticular Series of Two-Dimensional Covalent Organic Frameworks with the kgd Topology and Controllable Micropores.

Two-dimensional (2D) covalent organic frameworks (COFs) possess designable pore architectures but limited framework topologies. Until now, 2D COFs adopting the kgd topology with ordered and rhombic pore geometry have rarely been reported. Here, an isoreticular series of 2D COFs with the kgd topology and controllable pore size is synthesized by employing a C6-symmetric aldehyde, i.e., hexa(4-formylphenyl)benzene (HFPB), and C3-symmetric amines i.e., tris(4-aminophenyl)amine (TAPA), tris(4-aminophenyl)trazine (TAPT), and 1,3,5-tris[4-amino(1,1-biphenyl-4-yl)]benzene (TABPB), as building units, referred to as HFPB-TAPA, HFPB-TAPT, and HFPB-TABPB, respectively. The micropore dimension down to 6.7 Å is achieved in HFPB-TAPA, which is among the smallest pore size of reported 2D COFs. Impressively, both the in-plane network and stacking sequence of the 2D COFs can be clearly observed by low-dose electron microscopy. Integrating the unique kgd topology with small rhombic micropores, these 2D COFs are endowed with both short molecular diffusion length and favorable host-guest interaction, exhibiting potential for drug delivery with high loading and good release control of ibuprofen.

Synthesis of a magnetic π-extended carbon nanosolenoid with Riemann surfaces.

Riemann surfaces are deformed versions of the complex plane in mathematics. Locally they look like patches of the complex plane, but globally, the topology may deviate from a plane. Nanostructured graphitic carbon materials resembling a Riemann surface with helicoid topology are predicted to have interesting electronic and photonic properties. However, fabrication of such processable and large π-extended nanographene systems has remained a major challenge. Here, we report a bottom-up synthesis of a metal-free carbon nanosolenoid (CNS) material with a low optical bandgap of 1.97 eV. The synthesis procedure is rapid and possible on the gram scale. The helical molecular structure of CNS can be observed by direct low-dose high-resolution imaging, using integrated differential phase contrast scanning transmission electron microscopy. Magnetic susceptibility measurements show paramagnetism with a high spin density for CNS. Such a π-conjugated CNS allows for the detailed study of its physical properties and may form the base of the development of electronic and spintronic devices containing CNS species.

An Ultrahigh-Flux Nanoporous Graphene Membrane for Sustainable Seawater Desalination using Low-Grade Heat.

Membrane distillation has attracted great attention in the development of sustainable desalination and zero-discharge processes because of its possibility of recovering 100% water and the potential for integration with low-grade heat, such as solar energy. However, the conventional membrane structures and materials afford limited flux thus obstructing its practical application. Here, ultrathin nanoporous graphene membranes are reported by selectively forming thin graphene layers on the top edges of a highly porous anodic alumina oxide support, which creates short and fast transport pathways for water vapor but not liquid. The process avoids the challenging pore-generation and substrate-transfer processes required to prepare regular graphene membranes. In the direct-contact membrane distillation mode under a mild temperature pair of 65/25 °C, the nanoporous graphene membranes show an average water flux of 421.7 L m-2 h-1 with over 99.8% salt rejection, which is an order of magnitude higher than any reported polymeric membranes. The mechanism for high water flux is revealed by detailed characterizations and theoretical modeling. Outdoor field tests using water from the Red Sea heated under direct sunlight radiation show that the membranes have an average water flux of 86.3 L m-2 h-1 from 8 am to 8 pm, showing a great potential for real applications in seawater desalination.

Crystalline tetra-aniline with chloride interactions towards a biocompatible supercapacitor.

Recent advances in wearable and implantable electronics have increased the demand for biocompatible integrated energy storage systems. Conducting polymers, such as polyaniline (PANi), have been suggested as promising electrode materials for flexible biocompatible energy storage systems, based on their intrinsic structural flexibility and potential polymer chain compatibility with biological interfaces. However, due to structural disorder triggering insufficient electronic conductivity and moderate electrochemical stability, PANi still cannot fully satisfy the requirements for flexible and biocompatible energy storage systems. Herein, we report a biocompatible physiological electrolyte activated flexible supercapacitor encompassing crystalline tetra-aniline (c-TANi) as the active electrode material, which significantly enhances the specific capacitance and electrochemical cycling stability with chloride electrochemical interactions. The crystallization of TANi endows it with sufficient electronic conductivity (8.37 S cm-1) and a unique Cl- dominated redox charge storage mechanism. Notably, a fully self-healable and biocompatible supercapacitor has been assembled by incorporating polyethylene glycol (PEG) with c-TANi as a self-healable electrode and a ferric-ion cross-linked sodium polyacrylate (Fe3+-PANa)/0.9 wt% NaCl as a gel electrolyte. The as-prepared device exhibits a remarkable capacitance retention even after multiple cut/healing cycles. With these attractive features, the c-TANi electrode presents a promising approach to meeting the power requirements for wearable or implantable electronics.

Clinical analysis of excimer laser atherectomy in the treatment of diabetic foot with infrapopliteal arteriopathy / 中国医师杂志

Objective:To explore the clinical efficacy of excimer laser atherectomy (ELA) in the treatment of diabetic foot with infrapopliteal arteriopathy.Methods:The clinical data of 36 patients (40 limbs) with diabetic foot complicated with inferior knee artery disease treated by ELA in Xinjiang Uygur Autonomous Region People′s Hospital from December 2019 to May 2021 were analyzed retrospectively. The success rate of ELA in the treatment of diabetic inferior genicular artery disease, ankle-brachial index (ABI), limb salvage rate and Visual Analogue Scale (VAS) score at 3 days and 3 and 6 months after operation was observed.Results:All the 36 patients were operated successfully, including 2 cases of flow-limiting dissection, 2 cases of arterial embolism and 1 case of hematoma at the puncture point. The ABI of patients 3, 6 months after operation was significantly higher than that before operation (all P<0.05), and the VAS score 3, 6 months after operation was significantly lower than that before operation (all P<0.05). The rate of limb (toe) salvage were 92.5%(37/40), 82.5%(33/40) at 3 d, 3 months and 77.5%(31/40) at 6 months after operation. Conclusions:ELA is safe and effective in the treatment of diabetic foot infrapopliteal arteriopathy, and the recent efficacy is fair.