Formation of Coronene Clusters in Concentration and Temperature Controlled Two-Dimensional Porous Network

In this research, with the assistance of scanning tunneling microscopy (STM), we observed the two-dimensional (2D) self-assembly transition of a star-shaped oligofluorene derivative (StOF) from disordered structure to honeycomb network by adjusting StOF concentration in solution. By introducing guest molecules coronene (COR), we for the first time achieved novel triangle-shaped COR trimers on liquid/highly oriented pyrolytic graphite (HOPG) interface in both honeycomb network and the disordered structure. In thermal tests, the COR/StOF–disorder system underwent a structural conformation to form well-ordered ladder structures, while the COR/StOF–honeycomb system remained the perfect hexagonal network with COR trimers included in the cavities. Density functional theory (DFT) calculations have been employed to investigate the forming mechanism of the molecular nanoarrays. These studies are expected to enhance controlling on 2D self-assembly and provide a facial approach toward constructing on-surface molecular clusters

Consecutive Oxygen-for-Sulfur Exchange Reactions between Vanadium Oxide Cluster Anions and Hydrogen Sulfide

Vanadium oxide cluster anions V_<i>m</i>¹⁶O_<i>n</i>^– and V_<i>m</i>¹⁸O_<i>n</i>^– were prepared by laser ablation and reacted with hydrogen sulfide (H₂S) in a fast flow reactor under thermal collision conditions. A time-of-flight mass spectrometer was used to detect the cluster distributions before and after the interactions with H₂S. The experiments suggest that the oxygen-for-sulfur (O/S) exchange reaction to release water was evidenced in the reactor for most of the cluster anions: V_<i>m</i>O_<i>n</i>^– + H₂S → V_<i>m</i>O_<i>n</i>–1S^– + H₂O. For reactions of clusters VO₃^– and VO₄^– with H₂S, consecutive O/S exchange reactions led to the generation of sulfur containing vanadium oxide cluster anions VO_3–<i>k</i>S_<i>k</i>^– (<i>k</i> = 1–3) and VO_4–<i>k</i>S_<i>k</i>^– (<i>k</i> = 1–4). Density functional theory calculations were performed for the reactions of VO_3–4^– with H₂S, and the results indicate that the O/S exchange reactions are both thermodynamically and kinetically favorable, which supports the experimental observations. The reactions of V_<i>m</i>O_<i>n</i>⁺ cluster cations with H₂S have been reported previously (Jia, M.-Y.; Xu, B.; Ding, X.-L.; Zhao, Y.-X.; He, S.-G.; Ge, M.-F. J. Phys. Chem. C 2012, 116, 9043), and this study of cluster anions provides further new insights into the transformations of H₂S over vanadium oxides at the molecular level

Two-Dimensional Self-Assembly of a Pair of Triangular Macrocycles Studied by STM

In this investigation, we reported the two-dimensional (2D) self-assembly of a pair of triangular macrocycles (TMC1 and TMC2) at a highly oriented pyrolytic graphite (HOPG)/1-phenyloctane interface. Although with the similar triangle-shaped phenyl backbones, TMC1 and TMC2 displayed different 2D nanopatterns. Control experiments with varying concentrations and temperatures have been carried out. Phase separations were recorded in the coassembly of TMC1 and TMC2. Scanning tunneling microscopy (STM) measurements, as well as density function theory (DFT) calculations, revealed the formation mechanism of the TMC1 and TMC2 nanoarrays. Moreover, minor ring-opening phenomena of TMC2 were detected by STM, which demonstrates the advantages of STM in trace content analysis

Deinonychosaur trackways in southeastern China record a possible giant troodontid

Didactyl deinonychosaur tracks from the Longxiang tracksite (lower Upper Cretaceous, Shanghang Basin). 3D models (obj) of tracks LXIU-T3-R3, LXIU-T3-L3, LXIU-TI10</p

Rapid Discrimination of Malignant Breast Lesions from Normal Tissues Utilizing Raman Spectroscopy System: A Systematic Review and Meta-Analysis of In Vitro Studies

<div><p>Purpose</p><p>The aim of this study is to evaluate the diagnostic accuracy of Raman spectroscopy system in the detection of malignant breast lesions through a systemic review and meta-analysis of published studies.</p><p>Methods</p><p>We conducted a comprehensive literature search of PubMed and Embase from 2000 to June 2015. Published studies that evaluated the diagnostic performance of Raman spectroscopy in distinguishing malignant breast lesions from benign lesions and normal tissues were included in our study. The pooled sensitivity, specificity, diagnostic odds ratio, and the area under the curve of summary receiver-operating characteristic curves was derived. A Revised Tool for the Quality Assessment of Diagnostic Accuracy Studies guidelines was used to assess the quality of included studies.</p><p>Results</p><p>The initial search produced a total of 157 articles after removing duplicates. Nine studies (8 in vitro and 1 in vivo) were eligible in this meta-analysis. We analyzed the eight in vitro studies with 1756 lesions, the pooled sensitivity and specificity of Raman spectroscopy system for the diagnosis of malignant breast lesions were 0.92 (95% CI 0.86–0.96) and 0.97 (97% CI 0.93–0.98), respectively. Diagnostic odds ratio was 266.70 (95% CI 89.38–795.79), and the area under the curve of summary receiver-operating characteristic curves was 0.98 (95% CI 0.97–0.99). Significant heterogeneity was found between studies. There was no evidence of considerable publication bias.</p><p>Conclusions</p><p>Raman spectroscopy system is an optical diagnostic technology with great value for detecting malignant breast lesions. At the same time, it has advantages of being non-invasive, real-time, and easy to use. Thus it deserves to be further explored for intra-operatory breast tumor margin detection.</p></div

Core–Shell Palladium Nanoparticle@Metal–Organic Frameworks as Multifunctional Catalysts for Cascade Reactions

Uniform core–shell Pd@IRMOF-3 nanostructures, where single Pd nanoparticle core is surrounded by amino-functionalized IRMOF-3 shell, are prepared by a facile mixed solvothermal method. When used as multifunctional catalysts, the Pd@IRMOF-3 nanocomposites exhibit high activity, enhanced selectivity, and excellent stability in the cascade reaction. Both experimental evidence and theoretical calculations reveal that the high catalytic performance of Pd@IRMOF-3 nanocomposites originates from their unique core–shell structures

Formation of Ordered Coronene Clusters in Template Utilizing the Structural Transformation of Hexaphenylbenzene Derivative Networks on Graphite Surface

In the present work, we report the fabrication of regular coronene (COR) clusters on surfaces in ambient conditions in the two-dimensional network formed by hexaphenylbenzene derivatives (HPB) via structural transformation. HPB could form a stable snowflake network structure on the highly oriented pyrolytic graphite surface at the air–solid interface. When COR molecules were introduced into the system, the HPB snowflake network could transform to honeycomb structures, and the COR heptamers were subsequently aggregated and entrapped into the cavity. Scanning tunneling microscopic was employed to monitor the assembly behavior of both HPB and HPB/COR at a submolecule scale level, and density functional theory calculations were utilized to reveal that the structural transformation and the entrapment are the energetically favorable. The pores formed from HPB might also give a clue to immobilizing some functional molecule clusters, like COR, to fabricate their ordered monolayer in ambient conditions, so as to obtain complex supramolecular surface structures

The pooled sensitivity and specificity of Raman spectroscopy system (RAS).

<p>The pooled sensitivity and specificity of Raman spectroscopy system (RAS).</p

Characteristics of the 8 in vitro studies included in the meta-analysis.

<p>Characteristics of the 8 in vitro studies included in the meta-analysis.</p

The full screening and selection process.

<p>The full screening and selection process.</p