Ionic Liquid-Accelerated Growth of Covalent Organic Frameworks with Tunable Layer-Stacking.

Layer-stacking behaviors are crucial for two-dimensional covalent organic frameworks (2D COFs) to define their pore structure, physicochemical properties, and functional output. So far, fine control over the stacking mode without complex procedures remains a grand challenge. Herein, we proposed a "key-cylinder lock mimic" strategy to synthesize 2D COFs with a tunable layer-stacking mode by taking advantage of ionic liquids (ILs). The staggered (AB) stacking (unlocked) COFs were exclusively obtained by incorporating ILs of symmetric polarity and matching molecular size; otherwise, commonly reported eclipsed (AA) stacking (locked) COFs were observed instead. Mechanistic study revealed that AB stacking was induced by a confined interlocking effect (CIE) brought by anions and bulky cations of the ILs inside pores ("key" and "cylinder", respectively). Excitingly, this strategy can speed up production rate of crystalline powders (e.g., COF-TAPT-Tf@BmimTf2N in merely 30 minutes) under mild reaction conditions. This work highlights the enabling role of ILs to tailor the layer stacking of 2D COFs and promotes further exploration of their stacking mode-dependant applications.

Unveiling the Growth Mechanism of Ordered-Phase within Multimetallic Nanoplates.

Tuning the crystal phase of alloy nanocrystals (NCs) offers an alternative way to improve their electrocatalytic performance, but, how heterometals diffuse and form ordered-phase remains unclear. Herein, for the first time, the mechanism for forming tetrametallic ordered-phase nanoplates (NPLs) is unraveled. The observations reveal that the intermetallic ordered-phase nucleates through crystallinity alteration of the seeds and then propagates by reentrant grooves. Notably, the reentrant grooves act as intermediate NCs for ordered-phase, eventually forming intermetallic PdCuIrCo NPLs. These NPLs substantially outperform for oxygen evolution reaction (221 mV at 10 mA cm-2) and hydrogen evolution reaction (19 mV at 10 mA cm-2) compared to commercial Ir/C and Pd/C catalysts in acidic media. For OER at 1.53 V versus RHE, the PdCuIrCo/C exhibits an enhanced mass activity of 9.8 A mg-1 Pd+Ir (about ten times higher) than Ir/C. For HER at -0. 2 V versus RHE, PdCuIrCo/C shows a remarkable mass activity of 1.06 A mg-1 Pd+Ir, which is three-fold relative to Pd/C. These improvements can be ascribed to the intermetallic ordered-structure with high-valence Ir sites and tensile-strain. This approach enabled the realization of a previously unobserved mechanism for ordered-phase NCs. Therefore, this strategy of making ordered-phase NPLs can be used in diverse heterogeneous catalysis.

Linear Calcium Carbonate Chains by Directional Control of Ionic Bonding.

As a result of the non-directionality of ionic bonds, oppositely charged ions always assemble into closely packed clusters or crystals rather than linear structured ionic species. Here, we generated a series of linear calcium carbonate chains, (Ca2+CO32-)n, with an orientated directionality of the ionic interactions. The formation of these ionic chains with long-range ordered ionic interactions was originally induced by the dipole orientation of the ions and subsequently preserved by capping agents. According to the appropriately established folding-capping model, rational control of the capping effect can regulate the length of the (Ca2+CO32-)n chain within 100 nm, corresponding to n ≤ 250. Our discovery overturns the current understanding of ionic bonding in chemistry and opens a way to control the assembly of inorganic ions at molecular scale, pushing forward a fusion of molecular compounds and ionic compounds that share similar topological control.

Effect of Selective Metallic Defects on Catalytic Performance of Alloy Nanosheets.

Defects in the crystal structure of nanomaterials are important for their diverse applications. As, defects in 2D framework allow surface confinement effects, efficient molecular accessibility, high surface-area to volume-ratio and lead to higher catalytic activity, but it is challenging to expose defects of specific metal on the surface of 2D alloy and find the correlation between defective structure and electrocatalytic properties with atomic precision. Herein, the work paves the way for the controlled synthesis of ultrathin porous Ir-Cu nanosheets (NSs) with selectively iridium (Ir) rich defects to boost their performance for acidic oxygen evolution reaction (OER). X-ray absorption spectroscopy reveals that the oxidized states of Ir in defects of porous NSs significantly impact the electronic structure and decline the energy barrier. As a result, porous Ir-Cu/C NSs deliver improved OER activity with an overpotential of 237 mV for reaching 10 mA cm-2 and exhibit significantly higher mass activity than benchmark Ir/C under acidic conditions. Therefore, the present work highlights the concept of constructing a selective noble metal defect-rich open structure for catalytic applications.

Fabrication of water-floating litchi-like polystyrene-sphere-supported TiO2/Bi2O3 S-scheme heterojunction for efficient photocatalytic degradation of tetracycline.

The exploration of advanced photocatalysts for antibiotic degradation is critical, but it remains a challenge due to the lack of rational structural design and in-depth insights into molecular oxygen activation. Water-floating photocatalysts could be one of the best choices owing to their technical features in terms of reasonability and efficiency involving a high oxygenation of photocatalyst surface, fully solar irradiation, and simple recycling and reuse. Herein, a floatable litchi-like architecture of a polystyrene-sphere-supported TiO2/Bi2O3 (PS@TiO2/Bi2O3) S-scheme heterojunction was skillfully constructed and evaluated for photodegradation of model tetracycline (TC) antibiotics. By integrating the advantages of floatability and S-scheme, the TC removal rate of the optimal PS@TiO2/Bi2O3-0.4 catalyst can reach 88.4% under 1 h illumination, which is higher than that of pristine Bi2O3 (60.8%) and PS@TiO2 (40.1%). Moreover, PS@TiO2/Bi2O3-0.4 exhibits high recyclability and stability, and there is no significant loss of activity after five cycles of repeated use. With the aid of liquid chromatography-mass spectrometry analysis and density functional theory calculations, a reasonable degradation pathway for TC was proposed. The present work provides a recyclable and efficient approach for the photodegradation of TC, expecting to guide the innovative exploitation of other environmental systems.

Joint segmentation and named entity recognition using dual decomposition in Chinese discharge summaries.

OBJECTIVE: In this paper, we focus on three aspects: (1) to annotate a set of standard corpus in Chinese discharge summaries; (2) to perform word segmentation and named entity recognition in the above corpus; (3) to build a joint model that performs word segmentation and named entity recognition. DESIGN: Two independent systems of word segmentation and named entity recognition were built based on conditional random field models. In the field of natural language processing, while most approaches use a single model to predict outputs, many works have proved that performance of many tasks can be improved by exploiting combined techniques. Therefore, in this paper, we proposed a joint model using dual decomposition to perform both the two tasks in order to exploit correlations between the two tasks. Three sets of features were designed to demonstrate the advantage of the joint model we proposed, compared with independent models, incremental models and a joint model trained on combined labels. MEASUREMENTS: Micro-averaged precision (P), recall (R), and F-measure (F) were used to evaluate results. RESULTS: The gold standard corpus is created using 336 Chinese discharge summaries of 71 355 words. The framework using dual decomposition achieved 0.2% improvement for segmentation and 1% improvement for recognition, compared with each of the two tasks alone. CONCLUSIONS: The joint model is efficient and effective in both segmentation and recognition compared with the two individual tasks. The model achieved encouraging results, demonstrating the feasibility of the two tasks.

An end-to-end system to identify temporal relation in discharge summaries: 2012 i2b2 challenge.

OBJECTIVE: To create an end-to-end system to identify temporal relation in discharge summaries for the 2012 i2b2 challenge. The challenge includes event extraction, timex extraction, and temporal relation identification. DESIGN: An end-to-end temporal relation system was developed. It includes three subsystems: an event extraction system (conditional random fields (CRF) name entity extraction and their corresponding attribute classifiers), a temporal extraction system (CRF name entity extraction, their corresponding attribute classifiers, and context-free grammar based normalization system), and a temporal relation system (10 multi-support vector machine (SVM) classifiers and a Markov logic networks inference system) using labeled sequential pattern mining, syntactic structures based on parse trees, and results from a coordination classifier. Micro-averaged precision (P), recall (R), averaged P&R (P&R), and F measure (F) were used to evaluate results. RESULTS: For event extraction, the system achieved 0.9415 (P), 0.8930 (R), 0.9166 (P&R), and 0.9166 (F). The accuracies of their type, polarity, and modality were 0.8574, 0.8585, and 0.8560, respectively. For timex extraction, the system achieved 0.8818, 0.9489, 0.9141, and 0.9141, respectively. The accuracies of their type, value, and modifier were 0.8929, 0.7170, and 0.8907, respectively. For temporal relation, the system achieved 0.6589, 0.7129, 0.6767, and 0.6849, respectively. For end-to-end temporal relation, it achieved 0.5904, 0.5944, 0.5921, and 0.5924, respectively. With the F measure used for evaluation, we were ranked first out of 14 competing teams (event extraction), first out of 14 teams (timex extraction), third out of 12 teams (temporal relation), and second out of seven teams (end-to-end temporal relation). CONCLUSIONS: The system achieved encouraging results, demonstrating the feasibility of the tasks defined by the i2b2 organizers. The experiment result demonstrates that both global and local information is useful in the 2012 challenge.

[Reasons for recurrence and prognostic analysis of early stage squamous cell carcinoma of the oral tongue].

BACKGROUND AND OBJECTIVE: The therapeutic outcome of early stage squamous cell carcinoma of the oral tongue (SCCOT) is generally satisfactory. Recurrence is a major factor affecting the treatment efficacy of SCCOT. This study was to investigate the reasons for recurrence and prognostic factors of SCCOT, thus to decrease the recurrence rate and improve the therapeutic effect. METHODS: In total 227 patients with SCCOT treated in Sun Yat-sen University Cancer Center from January 1992 to December 2003 were retrospectively reviewed. The Kaplan-Meier method was used to analyze the survival rate, the log-rank test was used to compare survival distributions, and the Chi-square test was adopted to compare different factors affecting recurrence. Multivariate analysis was performed using the Cox proportional hazard model. RESULTS: The recurrence rate was significantly lower in patients with well differentiated SCCOT (19.3%) than in those with moderately-poorly differentiated SCCOT (39.2%) (P=0.004), and was significantly lower in patients receiving combined therapy (15%) than in those receiving surgery alone (28%) (P=0.014). The overall 3-year and 5-year survival rates in recurrent and non-recurrent groups were 40.7% vs. 87.3% and 25.9% vs. 80.3%, respectively(P=0.000). The overall 3-year and 5-year survival rates were also significantly different in patients > or =45 years and < 45 years (P=0.021), and in those with or without neck dissection (P=0.023). CONCLUSIONS: The pathological classification and whether receiving combination therapy are the factors affecting recurrence of SCCOT. Age, neck dissection and recurrence are prognostic factors of SCCOT. Age and recurrence are independent factors of SCCOT.