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Cyclodehydrogenation is an important ring-formation reaction that can directly produce planar-conjugated carbon-based nanomaterials from nonplanar molecules. However, inherently high C-H bond energy necessitates a high temperature during dehydrogenation, and the ubiquity of C - H bonds in molecules and small differences in their bond energies hinder the selectivity of dehydrogenation. Here, we report a room-temperature cyclodehydrogenation reaction on Au(111) via radical addition of open-shell resonance structures and demonstrate that radical addition significantly decreases cyclodehydrogenation temperature and further improves the chemoselectivity of dehydrogenation. Using scanning tunneling microscopy and non-contact atomic force microscopy, we visualize the cascade reaction process involved in cyclodehydrogenation and determine atomic structures and molecular orbitals of the planar acetylene-linked oxa-nanographene products. The nonplanar intermediates observed during progression annealing, combined with density functional theory calculations, suggest that room-temperature cyclodehydrogenation involves the formation of transient radicals, intramolecular radical addition, and hydrogen elimination; and that the high chemoselectivity of cyclodehydrogenation arises from the reversibility and different thermodynamics of radical addition step., (© 2024. The Author(s).)

Two-dimensional metal-organic networks (2D MONs) having heterogeneous coordination nodes (HCNs) could exhibit excellent performance in catalysis and optoelectronics because of the unbalanced electron distribution of the coordinating metals. Therefore, the design and construction of 2D MONs with HCNs are highly desirable but remain challenging. Here, we report the construction of 2D organometallic coordination networks with an organic Kagome lattice and a semiregular metal lattice on Au(111) via the in situ formation of HCNs. Using a bifunctional precursor 1,4-dibromo-2,5-diisocyanobenzene, the coordination of isocyano with Au adatom on a room-temperature Au(111) yielded metal-organic coordination chains with isocyano-Au-isocyano nodes. In contrast, on a high-temperature Au(111), a selective debromination/coordination cascade reaction occurred, affording 2D organometallic coordination networks with phenyl-Au-isocyano nodes. By combining scanning tunneling microscopy and density functional theory calculations, we determined the structures of coordination products and the nature of coordination nodes, demonstrating a thermodynamically favorable pathway for forming the phenyl-Au-isocyano nodes.

Precisely introducing topological defects is an important strategy in nanographene crystal engineering because defects can tune π-electronic structures and control molecular assemblies. The synergistic control of the synthesis and assembly of nanographenes by embedding the topological defects to afford two-dimensional (2D) crystals on surfaces is still a great challenge. By in-situ embedding ladder bipyrazinylene (LBPy) into acene, the narrowest nanographene with zigzag edges, we have achieved the precise preparation of 2D nonbenzenoid heteroacene crystals on Au(111). Through intramolecular electrocyclization of o-diisocyanides and Au adatom-directed [2+2] cycloaddition, the nonbenzenoid heteroacene products are produced with high chemoselectivity, and lead to the molecular 2D assembly via LBPy-derived interlocking hydrogen bonds. Using bond-resolved scanning tunneling microscopy, we determined the atomic structures of the nonbenzenoid heteroacene product and diverse organometallic intermediates. The tunneling spectroscopy measurements revealed the electronic structure of the nonbenzenoid heteroacene, which is supported by density functional theory (DFT) calculations. The observed distinct organometallic intermediates during progression annealing combined with DFT calculations demonstrated that LBPy formation proceeds via electrocyclization of o-diisocyanides, trapping of heteroarynes by Au adatoms, and stepwise elimination of Au adatoms., (© 2024 Wiley-VCH GmbH.)

Two-dimensional (2D) crystal-to-crystal transition is an important method in crystal engineering because of its ability to directly create diverse crystal materials from one crystal. However, steering a 2D single-layer crystal-to-crystal transition on surfaces with high chemo- and stereoselectivity under ultra-high vacuum conditions is a great challenge because the transition is a complex dynamic process. Here, we report a highly chemoselective 2D crystal transition from radialene to cumulene with retention of stereoselectivity on Ag(111) via retro-[2 + 1] cycloaddition of three-membered carbon rings and directly visualize the transition process involving a stepwise epitaxial growth mechanism by the combination of scanning tunneling microscopy and non-contact atomic force microscopy. Using progression annealing, we found that isocyanides on Ag(111) at a low annealing temperature underwent sequential [1 + 1 + 1] cycloaddition and enantioselective molecular recognition based on C-H···Cl hydrogen bonding interactions to form 2D triaza[3]radialene crystals. In contrast, a higher annealing temperature induced the transformation of triaza[3]radialenes to generate trans -diaza[3]cumulenes, which were further assembled into 2D cumulene-based crystals through twofold N-Ag-N coordination and C-H···Cl hydrogen bonding interactions. By combining the observed distinct transient intermediates and density functional theory calculations, we demonstrate that the retro-[2 + 1] cycloaddition reaction proceeds via the ring opening of a three-membered carbon ring, sequential dechlorination/hydrogen passivation, and deisocyanation. Our findings provide new insights into the growth mechanism and dynamics of 2D crystals and have implications for controllable crystal engineering.

The emergence of quantum magnetism in nanographenes provides ample opportunities to fabricate purely organic devices for spintronics and quantum information. Although heteroatom doping is a viable way to engineer the electronic properties of nanographenes, the synthesis of doped nanographenes with collective quantum magnetism remains elusive. Here, a set of nitrogen-doped nanographenes (N-NGs) with atomic precision are fabricated on Au(111) through a combination of imidazole [2+2+2]-cyclotrimerization and cyclodehydrogenation reactions. High-resolution scanning probe microscopy measurements reveal the presence of collective quantum magnetism for nanographenes with three radicals, with spectroscopic features which cannot be captured by mean-field density functional theory calculations but can be well reproduced by Heisenberg spin model calculations. In addition, the mechanism of magnetic exchange interaction of N-NGs has been revealed and compared with their counterparts with pure hydrocarbons. Our findings demonstrate the bottom-up synthesis of atomically precise N-NGs which can be utilized to fabricate low-dimensional extended graphene nanostructures for realizing ordered quantum phases.

Dendronized polymers (DPs) consist of a linear polymeric backbone with dendritic side chains. Fine-tuning of the functional groups in the side chains enriches the structural versatility of the DPs and imparts a variety of novel physical properties. Herein, the first on-surface synthesis of DPs is achieved via the postfunctionalization of polymers on Au(111), in which the surface-confinement-induced planar conformation and chiral configurations were unambiguously characterized. While the dendronized monomer was synthesized in situ on Au(111), the subsequent polymerization afforded only short, cross-linked DP chains owing to multiple side reactions. The postfunctionalization approach selectively produced brominated polyphenylene backbone moieties by the deiodination polymerization of 4-bromo-4″-iodo-5'-(4-iodophenyl)-1,1':3',1″-terphenyl on Au(111), which smoothly underwent divergent cross-coupling reactions with two different isocyanides to form two types of DPs as individual long chains.

Background: Fractures of the medial clavicle are uncommon. There is no consensus regarding the optimal treatment of displaced medial clavicle fractures., Methods: A systematic review using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was performed. PubMed, EMBASE, and the Cochrane Library were queried using the terms medial clavicle and fracture to identify all studies reporting on outcomes following either nonoperative or operative treatment of displaced medial clavicle fractures. Data extracted included patient demographics, fracture classification, surgical technique, patient-reported outcomes, physical, and radiographic findings. Study quality was evaluated using the Methodological Index for Non-Randomized Studies (MINORS) scoring system., Results: The analysis included 15 studies (mean MINORS score, 10 ± 1.5) with a total of 135 patients (85% male, mean age 47 ± 10.9 years [range, 15-87 years]). Five studies (39 patients) reported outcomes following nonoperative treatment. At a mean follow-up of 27 months, there were 5 (13%) symptomatic nonunions, 2 (5%) malunions, and 2 (5%) delayed unions. Eleven studies (96 patients) reported outcomes following surgical treatment with a mean follow-up of 23 months. There were no reported nonunions. Complications included plate prominence/ irritation (30%) and additional surgery was performed for plate removal (27%), fixation failure (3%), and wound débridement (1%)., Conclusion: There is limited, low-quality evidence in the literature to guide treatment of displaced medial clavicle fractures. The available data suggest that surgical treatment is associated with good functional outcomes and a lower risk of nonunion and malunion, compared to nonoperative treatment but plate irritation and further surgery to remove the plate was common., (© 2022 Published by Elsevier Inc. on behalf of American Shoulder and Elbow Surgeons.)

[3]Radialenes are the smallest carbocyclic structures with unusual topologies and cross-conjugated π-electronic structures. Here, we report a novel [1+1+1] cycloaddition reaction for the synthesis of aza[3]radialenes on the Ag(111) surface, where the steric hindrance of the chlorine substituents guides the selective and orientational assembling of the isocyanide precursors. By combining scanning tunneling microscopy, non-contact atomic force microscopy, and time-of-flight secondary ion mass spectrometry, we determined the atomic structure of the produced aza[3]radialenes. Furthermore, two reaction pathways including synergistic and stepwise are proposed based on density functional theory calculations, which reveal the role of the chlorine substituents in the activation of the isocyano groups via electrostatic interaction., (© 2022 Wiley-VCH GmbH.)

Molecular adsorption conformations and arrangement configurations on surfaces are important structural aspects of surface stereochemistry, but their roles in steering the structures of metal-organic networks (MONs) remain vague and unexplored. In this study, we constructed MONs by the coordination self-assembly of isocyanides on Cu(111) and Ag(111) surfaces and demonstrated that the MON structures can be steered by surface stereochemistry, including the adsorption conformations of the isocyanide molecules and the arrangement configurations of the coordination nodes and subunits. The coordination self-assembly of 1,4-phenylene diisocyanobenzene afforded a honeycomb MON consisting of 3-fold (isocyano) 3 -Cu motifs on a Cu(111) surface. In contrast, geometrically different chevron-shaped 1,3-phenylene diisocyanobenzene ( m -DICB) failed to generate a MON, which is ascribable to its standing conformation on the Cu(111) surface. However, m -DICB was adsorbed in a flat conformation on a Ag(111) surface, which has a larger lattice constant than a Cu(111) surface, and smoothly underwent coordination self-assembly to form a MON consisting of (isocyano) 3 -Ag motifs. Interestingly, only C 3 -Ag nodes with heterotactic configurations could grow into larger subunits; those subunits with heterotactic configurations further grew into Sierpiński triangle fractals (up to fourth order), while subunits with homotactic configurations afforded a triangular MON.

Background: Dietary iron intake and serum ferritin in relation to severe headache or migraine remain largely unknown. Therefore, we investigated the associations between dietary iron intake and serum ferritin with severe headache or migraine among American adults. Methods: This cross-sectional study included 7,880 adults (≥20 years) from the National Health and Nutrition Examination Surveys (NHANES) of America from 1999 to 2004. We performed multivariable logistic regression and restricted cubic spline (RCS) regression to assess the association of dietary iron and serum ferritin with severe headache or migraine. Results: Most women aged 20-50 years consumed less dietary iron than their recommended dietary allowances. Dietary iron intake was inversely associated with severe headache or migraine in women aged 20-50 years. For women over 50 years, serum ferritin was negatively associated with severe headache or migraine. For men, there was no significant relationship between dietary iron and serum ferritin, and severe headache or migraine. Conclusions: Dietary iron intake has different effects on migraine in women of different ages, and this different effect may be due to age-related menstrual changes. Women aged 20-50 years should have a higher awareness of RDA and increase their dietary iron intake if needed, which may play an important role in preventing severe headache or migraine. Higher serum ferritin levels in women aged 50 and above may have a protective effect against migraine., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Meng, Zhou, Li, Wang, Kang, Fu, Li, Li and Zhao.)

Penicillium oxalicum k10 isolated from soil revealed the hydrolyzing ability of shrimp chitin and antifungal activity against Sclerotinia sclerotiorum. The k10 chitinase was produced from a powder chitin-containing medium and purified by ammonium sulfate precipitation and column chromatography. The purified chitinase showed maximal activity toward colloidal chitin at pH 5 and 40 °C. The enzymatic activity was enhanced by potassium and zinc, and it was inhibited by silver, iron, and copper. The chitinase could convert colloidal chitin to N-acetylglucosamine (GlcNAc), (GlcNAc)2, and (GlcNAc)3, showing that this enzyme had endocleavage and exocleavage activities. In addition, the chitinase prevented the mycelial growth of the phytopathogenic fungi S. sclerotiorum and Mucor circinelloides. These results indicate that k10 is a potential candidate for producing chitinase that could be useful for generating chitooligosaccharides from chitinous waste and functions as a fungicide.

Background: Migraine is a common neurological disorder and is affected by nutrients. Calcium and magnesium are essential minerals that play an important role in nerve function. So we investigated the association between dietary calcium and magnesium and migraine. Methods: We extracted 10,798 adults from the National Health and Nutrition Examination Surveys (NHANES) of America in 1999 to 2004. We classified patients who reported having severe headache or migraine as having possible migraine. Multivariable logistic regression and restricted cubic spline regression were conducted to determine the association between dietary calcium and magnesium and migraine. Results: We found that the adjusted ORs of the association between dietary calcium and magnesium and migraine for comparing the highest quintile intake with the lowest quintile intake were 0.77 (95% CI: 0.63-0.93, P = 0.008) and 0.69 (95% CI: 0.55-0.86, P = 0.001), respectively. For women, the adjusted ORs of dietary calcium and magnesium were 0.72 (95% CI: 0.56-0.93, P = 0.009) and 0.62 (95% CI: 0.47-0.83, P = 0.001), respectively. For men, the adjusted OR was 0.71 (95% CI: 0.52-0.97, P = 0.028) comparing the highest and the lowest quintile of calcium intake, but there was no statistically significant association between dietary magnesium intake and migraine. Joint analyses showed that the OR in the high-calcium and high-magnesium group was 0.74 (95% CI: 0.60-0.92, P = 0.006) compared with the low-calcium and low-magnesium group in women. Conclusions: High dietary intake of calcium and magnesium, independently or in combination, were inversely associated with migraine in women. For men, high dietary calcium was negatively related to migraine, but magnesium was not associated with migraine., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Meng, Wang, Kang, Fu, Zhou, Li, Li, Li and Zhao.)

MicroRNA-181a (miR-181a) is upregulated in osteosarcoma, and its overexpression promotes the proliferation and inhibits the apoptosis of osteosarcoma cells. However, the mechanism of miR‑181a as an oncogene remains to be fully elucidated in osteosarcoma. Cleavage factor (CF) Im25 links alternative polyadenylation to glioblastoma tumor suppression, however, its role in osteosarcoma has not been reported. In the present study, it was confirmed that the expression of miR‑181a was upregulated in osteosarcoma, and that silencing miR‑181a inhibited the proliferation and promoted the apoptosis of osteosarcoma cells. miRNAs are short non‑coding RNAs, which regulate target mRNAs by binding predominantly to the 3'untranslated region (3'UTR), inducing either translational repression or degradation of the target. In the present study, target genes of miR‑181a were screened using miRanda, which is a commonly used prediction algorithm. It was found that miR‑181a targeted the 3'UTR of CFIm25 mRNA. Subsequent experiments confirmed that miR‑181a downregulated the expression of CFIm25 in osteosarcoma cells. Finally, it was demonstrated that the CFIm25 protein was also downregulated in osteosarcoma tissues, and inhibited the proliferation and promoted the apoptosis of the cells. Elucidating the roles of miR‑181a and CFIm25 in osteosarcoma not only assists in further understanding the pathogenesis and progression of this disease, but also offers novel targets for effective therapies.

In this study, we conducted an investigation among medical workers, patients and college students concerning their acceptability of breast palpation performed by male doctors (hereinafter referred to as "acceptability", or "the examination", respectively, if not otherwise indicated), to get the information about their acceptability and reasons for accepting or declining the examination among the three population. A questionnaire investigation was conducted in 500 patients with breast diseases, 700 students of medical colleges, and 280 medical workers working in hospitals. The subjects were asked to choose between two options: accept or do not accept (the examination). The subjects were asked to fill out the questionnaire forms on free and anonymous basis and the questionnaire forms were collected on spot, immediately after completion. The questionnaires collected were coded, sorted out and checked. Data of the eligible questionnaires were input into Epidata software and analyzed by SPSS. Upon the establishment of the database, the intra-group data were tested by utilizing χ(2) test. Among 1480 questionnaires, 1293 (90.41%) questionnaires were retrieved. Our results showed that 56.78% of patients reported that they could accept breast palpation by male doctors. About 59.66% of medical staff expressed their acceptance of the examination, but only 35.03% of students said the examination. On the basis of this study, we were led to conclude that the examination is not well accepted by different populations, and therefore, (1) medical professionals and administrators should pay attention to the gender-related ethics in their practice and the feeling of patients should be respected when medical examinations involve private or sensitive body parts; (2) to this end, related departments should be properly staffed with doctors of both sexes, and this is especially true of the departments involving the examination or treatment of private or sensitive body parts; (3) health education should, among other things, include helping female patients to overcome the fear and anxiety in such examinations. This is of great importance since some women may miss the opportunity to get timely diagnosis.

The cooperativity effects between the O/N-H∙∙∙O hydrogen-bonding and Na⁺∙∙∙O cation-molecule interactions in the 1: 2 (Na⁺: N-(Hydroxymethyl)acetamide) systems were investigated at the B3LYP/6-311++G**, MP2(full)/6-311++G** and MP2(full)/aug-cc-pvtz levels. The thermodynamic cooperativity calculations were also carried out for two pathways of the ternary-complex formation. The result shows that, in most ternary complexes, the O/N-H∙∙∙O and Na⁺∙∙∙O interactions are weakened in comparison with those in binary systems, leading to the anti-cooperativity effects, in particular in the complexes in which only the Na⁺∙∙∙O interactions exist. Shifts of electron density confirm the existence of anti-cooperativity. The increase of favorable enthalpic contribution leads to the positive cooperativity effect with negative ΔG(coop.) on forming the ternary complex by initial N-(Hydroxymethyl)acetamide dimer followed by addition of Na⁺. In forming the ternary complex by Na⁺∙∙∙N-(Hydroxymethyl)acetamide with the second N-(Hydroxymethyl)acetamide unit, the large unfavorable entropy change leads to the negative cooperativity effect with positive ΔG(coop.). The ternary complex is more easily formed by the pathway in which Na⁺ binds to N-(Hydroxymethyl)acetamide dimer.

A chitosanase-producing bacterium, Bacillus subtilis HD145 CCTCC AB 2010353, was isolated from a soil sample. The gene (csn) encoding chitosanase was cloned, sequenced, and expressed in the Pichia pastoris strain as a soluble and active form. Its expression level could be as high as 800 mg/L, and enzymatic activity reached approximately 9000 U/mg. The optimum pH and temperature were 5.5 and 50 °C, respectively. The recombinant protein was partially glycosylated. Its half lives at temperatures of 50 and 60 °C were 26 h and 23 min, respectively. Enzymatic activity was increased with an increasing degree of deacetylation of chitosan. The enzymatic productions of chitooligosaccharides from chitosans of various deacetylation degrees mainly ranged from chitobiose to chitopentamer., (Copyright © 2012 Elsevier Ltd. All rights reserved.)