Lighting Up Nonemissive Azobenzene Derivatives by Pressure.

Pressure-induced emission (PIE) is a compelling phenomenon that can activate luminescence within nonemissive materials. However, PIE in nonemissive organic materials has never been achieved. Herein, we present the first observation of PIE in an organic system, specifically within nonemissive azobenzene derivatives.

Visual Evaluation of Urban Streetscape Design Supported by Multisource Data and Deep Learning.

This paper integrates classical design theory, multisource urban data, and deep learning to explore an accurate analytical framework in a new data environment, providing a scientific analysis path for the "where" and "how" of greenways in a high-density built environment. The analysis is based on street view data and location service data. Through the integration of multiple data sources such as street scape data, location service data, point-of-interest data, structured web data, and refined built environment data, a systematic measurement of the key elements of density, diversity, design, accessibility to destinations, and distance to transport facilities as defined in the Five Elements of High Quality Built Environment (5D) theory is achieved.

Pressure-Induced Local Excitation Promotion: New Route toward High-Efficiency Aggregate Emission Based on Multimer Excited State Modulation.

Achieving high-efficiency solid state emission is essential for practical applications of organic luminescent materials. However, intermolecular interactions generally induce formation of multimeric aggregate excited states with deficient emissive ability, making it extremely challenging to enhance emission in aggregated states. Here we demonstrate a novel strategy of continuously regulating multimeric excitation constituents with a high-pressure technique successfully enhancing the emission in a representative organic charge-transfer material, Laurdan (6-lauroyl-,-dimethyl-2-naphthylamine).

Experimental Observation of the High Pressure Induced Substitutional Solid Solution and Phase Transformation in SbS.

The substitutional solid solutions composed of group VA-VIA nonmetallic elements has attracted considerable scientific interest since they provide a pressure-induced route to search for novel types of solid solutions with potential applications. Yet, the pressure-induced solid solution phase is unprecedented in the sulfide family. In this paper, the structural behavior of antimony trisulfide, SbS, has been investigated in order to testify whether or not it can also be driven into the substitutional solid solution phase by high pressures.

Nanodiamonds: a critical component of anodes for high performance lithium-ion batteries.

Detonation nanodiamonds (DNDs) have been introduced into a carbonaceous anode for improving the performance of lithium ion batteries (LIBs). The lithium storage capacity, cycling performance and stability of the LIBs are increased and this is related to the DNDs' unique characteristics of chemical inertness, a larger surface area, low expansion, and high lithium adsorption capacity.

Molecular Mechanisms for High Hydrostatic Pressure-Induced Wing Mutagenesis in Drosophila melanogaster.

Although High hydrostatic pressure (HHP) as an important physical and chemical tool has been increasingly applied to research of organism, the response mechanisms of organism to HHP have not been elucidated clearly thus far. To identify mutagenic mechanisms of HHP on organisms, here, we treated Drosophila melanogaster (D. melanogaster) eggs with HHP.

Synthesis of Hollow β-Phase GeO2 Nanoparticles.

We fabricated mono-dispersed hollow waxberry shaped β-quartz GeO2 by a facile one-step synthesis in emulsion at room temperature. TEM images indicated that hollow waxberry shaped GeO2 were consisted of nano-sphere whose average size were estimated to be 20 nm. The growth mechanism and optical properties of the products were also investigated.

A Protocol to Fabricate Nanostructured New Phase: B31-Type MnS Synthesized under High Pressure.

Synthesis of nanomaterials with target crystal structures, especially those new structures that cannot be crystallized in their bulk counterparts, is of considerable interest owing to their strongly structure-dependent properties. Here, we have successfully synthesized and identified new-phase nanocrystals (NCs) associated with orthorhombic MnP-type (B31) MnS by utilizing an effective high-pressure technique. It is particularly worth noting that the generated new structured MnS NCs were captured as expected by quenching the high-pressure phase to the ambient conditions at room temperature.

Reactions of xenon with iron and nickel are predicted in the Earth's inner core.

Studies of the Earth's atmosphere have shown that more than 90% of the expected amount of Xe is depleted, a finding often referred to as the 'missing Xe paradox'. Although several models for a Xe reservoir have been proposed, whether the missing Xe could be contained in the Earth's inner core has not yet been answered. The key to addressing this issue lies in the reactivity of Xe with Fe/Ni, the main constituents of the Earth's core.

Robust diamond meshes with unique wettability properties.

Robust diamond meshes with excellent superhydrophobic and superoleophilic properties have been fabricated. Superhydrophobicity is observed for water with varying pH from 1 to 14 with good recyclability. Reversible superhydrophobicity and hydrophilicity can be easily controlled.

Unexpected room-temperature ferromagnetism in nanostructured Bi2Te3.

There is an urgent need for the development in the field of the magnetism of topological insulators, owing to the necessity for the realization of the quantum anomalous Hall effect. Herein, we discuss experimentally fabricated nanostructured hierarchical architectures of the topological insulator Bi2Te3 without the introduction of any exotic magnetic dopants, in which intriguing room-temperature ferromagnetism was identified. First-principles calculations demonstrated that the intrinsic point defect with respect to the antisite Te site is responsible for the creation of a magnetic moment.

Pressure-induced isosymmetric phase transition in sulfamic acid: a combined Raman and x-ray diffraction study.

High-pressure behaviors of hydrogen-bonded molecular crystal, sulfamic acid (NH3(+)SO3(-), SA), have been investigated using Raman spectroscopy and synchrotron X-ray diffraction (XRD) techniques up to the pressure of ~20 GPa. Under ambient conditions, molecules of SA are arranged in puckered layers and held together by hydrogen bonding and electrostatic interactions. It is proved by the Raman results that SA undergoes the molecular conformation changes in the pressure range 8.

Resonant tunneling modulation in quasi-2D Cu(2)O/SnO(2) p-n horizontal-multi-layer heterostructure for room temperature H(2)S sensor application.

Heterostructure material that acts as resonant tunneling system is a major scientific challenge in applied physics. Herein, we report a resonant tunneling system, quasi-2D Cu(2)O/SnO(2) p-n heterostructure multi-layer film, prepared by electrochemical deposition in a quasi-2D ultra-thin liquid layer. By applying a special half-sine deposition potential across the electrodes, Cu(2)O and SnO(2) selectively and periodically deposited according to their reduction potentials.

Size-controlled synthesis of bifunctional magnetic and ultraviolet optical rock-salt MnS nanocube superlattices.

Wide-band-gap rock-salt (RS) MnS nanocubes were synthesized by the one-pot solvent thermal approach. The edge length of the nanocubes can be easily controlled by prolonging the reaction time (or aging time). We systematically explored the formation of RS-MnS nanocubes and found that the present synthetic method is virtually a combination of oriented aggregation and intraparticle ripening processes.

Exploration of the pyrazinamide polymorphism at high pressure.

We report the high-pressure response of three forms (α, δ, and γ) of pyrazinamide (C(5)H(5)N(3)O, PZA) by in situ Raman spectroscopy and synchrotron X-ray diffraction techniques with a pressure of about 14 GPa. These different forms are characterized by various intermolecular bonding schemes. High-pressure experimental results show that the γ phase undergoes phase transition to the β phase at a pressure of about 4 GPa, whereas the other two forms retain their original structures at a high pressure.

Compression studies of face-to-face π-stacking interaction in sodium squarate salts: Na2C4O4 and Na2C4O4●3H2O.

High-pressure Raman scattering and synchrotron X-ray diffraction measurements of sodium squarate (Na(2)C(4)O(4), SS) are performed in a diamond anvil cell. SS possesses a rare, but typical structure, which can show the effect of face-to-face π-stacking without interference of other interactions. At ~11 GPa, it undergoes a phase transition, identified as a symmetry transformation from P2(1)/c to P2(1).

Controlled synthesis of hollow Cu₂-x Te nanocrystals based on the Kirkendall effect and their enhanced CO gas-sensing properties.

This paper develops a facile solution-based method to synthesize hollow Cu2-x Te nanocrystals (NCs) with tunable interior volume based on the Kirkendall effect. Transmission electron microscopy images and time-dependent absorption spectra reveal the temporal growth process from solid copper nanoparticles to hollow Cu2-x Te NCs. Furthermore, the as-prepared hollow Cu2-x Te NCs show enhanced sensitivity for the detection of carbon monoxide (CO), which is often referred to as the "silent killer".

Synthesis and high-pressure transformation of metastable wurtzite-structured CuGaS2 nanocrystals.

The metastable wurtzite nanocrystals of CuGaS(2) have been synthesized through a facile and effective one-pot solvothermal approach. Through the Rietveld refinement on experimental X-ray diffraction patterns, we have unambiguously determined the structural parameters and the disordered nature of this wurtzite phase. The metastability of wurtzite structure with respect to the stable chalcopyrite structure was testified by a precise theoretical total energy calculation.

Calcium with the β-tin structure at high pressure and low temperature.

Using synchrotron high-pressure X-ray diffraction at cryogenic temperatures, we have established the phase diagram for calcium up to 110 GPa and 5-300 K. We discovered the long-sought for theoretically predicted β-tin structured calcium with I4(1)/amd symmetry at 35 GPa in a s mall low-temperature range below 10 K, thus resolving the enigma of absence of this lowest enthalpy phase. The stability and relations among various distorted simple-cubic phases in the Ca-III region have also been examined and clarified over a wide range of high pressures and low temperatures.

Pressure-induced phase transition in N-H···O hydrogen-bonded molecular crystal oxamide.

The effect of high pressure on the structural stability of oxamide has been investigated in a diamond anvil cell by Raman spectroscopy up to ∼14.6 GPa and by angle-dispersive X-ray diffraction (ADXRD) up to ∼17.5 GPa.

Effect of high pressure on the typical supramolecular structure of guanidinium methanesulfonate.

We report the high-pressure response of guanidinium methanesulfonate (C(NH(2))(3)(+)·CH(3)SO(3)(-), GMS) using in situ Raman spectroscopy and synchrotron X-ray diffraction (XRD) techniques up to the pressures of ~11 GPa. GMS exhibits the representative supramolecular structure of two-dimensional (2D) hydrogen-bonded bilayered motifs under ambient conditions. On the basis of the experimental results, two phase transitions were identified at 0.

Spiral chain O₄ form of dense oxygen.

Oxygen is in many ways a unique element: It is the only known diatomic molecular magnet, and it exhibits an unusual O(8) cluster in its high-pressure solid phase. Pressure-induced molecular dissociation as one of the fundamental problems in physical sciences has been reported from theoretical or experimental studies of diatomic solids H(2), N(2), F(2), Cl(2), Br(2), and I(2) but remains elusive for molecular oxygen. We report here the prediction of the dissociation of molecular oxygen into a polymeric spiral chain O(4) structure (space group I4(1)/acd, θ-O(4)) above 1.

ZnS nanocrystals and nanoflowers synthesized by a green chemistry approach: rare excitonic photoluminescence achieved by the tunable molar ratio of precursors.

In the present work, we demonstrated a simple and green synthesis route for shape-controlled ZnS nanocrystals, where only environmentally benign chemicals, namely sulfur, zinc oxide and olive oil, were employed. By controlling the experimental conditions, we were able to tune the band edge and trap state photoluminescences of ZnS nanocrystals and obtain pure excitonic photoluminescence that was rarely observed in literature. The trap state emission was derived from sulfur vacancies and would be eliminated when an excess of sulfur was used during the synthesis.

Rhodium dihydride (RhH2) with high volumetric hydrogen density.

Materials with very high hydrogen density have attracted considerable interest due to a range of motivations, including the search for chemically precompressed metallic hydrogen and hydrogen storage applications. Using high-pressure synchrotron X-ray diffraction technique and theoretical calculations, we have discovered a new rhodium dihydride (RhH(2)) with high volumetric hydrogen density (163.7 g/L).

Pressure-induced amorphization in mayenite (12CaO·7Al2O3).

We report a joint experimental and theoretical study on high pressure structures of nanoporous mayenite (12CaO·7Al(2)O(3)). A pressure-induced amorphization was identified at ∼13 GPa by in situ high pressure x-ray experiments. The amorphous product can be decompressed to ambient conditions.