Decomposition process of bastnaesite concentrate in NaOH-CaO-H_2O system

A novel process of calcification-leaching for bastnaesite concentrate(REFCO_3) was proposed. The prior calcification was carried out in the system of NaOH-CaO-H_2O and the lgC-pH pattern for Ce-F-Ca-C-H_2O system was drawn. The thermodynamics result indicates that decomposition for bastnaesite requires certain alkaline condition, but excessive alkalinity also causes decomposition of CaF_2. XRD and SEM-EDS analyses on the calcification-leaching process reveal that bastnaesite first decomposes into RE(OH)_3 and CaF_2. Then, by HCl leaching rare earths were extracted,while CaF_2 was left in the leaching residue. In addition, effects of temperature, time, NaOH and CaO on the calcification were investigated. The results show that the leaching rate of rare earths(REs)reaches 72.5 wt%, at the same time 99.2 wt% of F is left in leaching residue with 20 wt% NaOH and 38 wt% CaO at 493 K for 180 min.     

The effects of molecular configuration on the photochromism and decolorization of two bipyridinium-based coordination polymers

Two layer-like coordination polymers, {[Cd(Bpyen)_0.5(m-BDC)(H₂O)Br]·4H₂O}(1) and {[Cd(Bpyen)_0.5(o-BDC)Br]·H₂O}(2), have been solvothermally synthesized and structurally characterized. The two compounds own common rapid photochromic response but different decolorization behaviors. The photoproduct of compound 2 is more stable in air. The relationship between structure and photoresponsive behavior has been studied in detail.     

A fluorescence chemosensor for benzonitrile derived from in-situ synthesis of azolate–carboxylic acid and zinc(II) ions

A new zinc(II) homometallic coordination polymer (CP), {[Zn(TAA-OH)₂] · 1.5H₂O}_n (1) (HTAA-OH = 2-(5-hydroxy-1H-1,2,4-triazole-1-yl) acetic acid) has been synthesized via an in-situ synthetic approach and structurally characterized in detail. In 1, the HTAA-OH ligand is generated in-situ by the nucleophilic addition of 2-(1H-1,2,4-triazole-1-yl) acetic acid. CP 1 features a 2D structure with sql topology, where the neighboring Zn(II) ions are bridged through two oxygen atoms of carboxyl group and two nitrogen atoms of triazole from the HTAA-OH ligands. Luminescence study shows that 1 dispersed in acetonitrile performs a distinct luminescence enhancing effect upon addition of benzonitrile, indicating that 1 is a promising fluorescence chemosensor for benzonitrile.     

Polymers of phenylenediamines

The chemical or electrochemical oxidation of phenylenediamines in acidic aqueous media yields the corresponding oligomers or polymers. Their structures and properties are discussed in relation to a closely-related conducting polymer, polyaniline. Depending on the reaction conditions, polyphenylenediamines are produced as powders, colloidal dispersions, thin films, or composites. In contrast to polyaniline, polyphenylenediamines are rated as non-conductors and their conductivities are low. Similarly to polyaniline, these polymers display a salt–base transition and they are redox-active. They act as reductants of noble-metal compounds to the corresponding metals or as precursors in the carbonization to nitrogen-rich carbons. Applications proposed in the literature are outlined; they include the corrosion protection of metals, catalysis, electrorheology, sensors, energy-conversion devices, electrochromism, noble-metal recovery, and water treatment.     

Fabricating NixCo1−xO@C cocatalysts sensitized by CdS through electrostatic interaction for efficient photocatalytic H2 evolution

Exploiting efficient and stable noble metal-free hydrogen evolution catalysts for water splitting is of great importance. In this work, Ni_xCo_1-xO@C/CdS hybrid is successfully fabricated through an electrostatic interaction of oppositely charged nanoparticles on their surfaces. The resulting Ni_xCo_1-xO@C nanoboxes cocatalysts which were derived from NiCo-LDH@ZIF-67 with Ni–Co layered double hydroxides (LDH) decorated with ZIF-67 precursor exhibited improved hydrogen production rate compared with bare CdS semiconductor from 0.7 mmol g⁻¹ h⁻¹ to 56 mmol g⁻¹ h⁻¹. It is demonstrated that the electrostatic interaction between the two surface charged nanoparticles of Ni_xCo_1-xO@C and CdS play an important role in migrating and separating of photogenerated charge carriers. The synthesized Ni_xCo_1-xO@C as excellent candidates for cost-effective cocatalysts is aimed to substitute for noble metals in photocatalytic H₂ evolution.     

Modification of the ultrasonication derived-g-C3N4 nanosheets/quantum dots by MoS2 nanostructures to improve electrocatalytic hydrogen evolution reaction

In this work, graphitic carbon nitride (g-C₃N₄) nanosheets/quantum dots (NS/QD) was prepared using a simple and low-cost procedure. By two steps exfoliation in a bath and tip sonicator, the g-C₃N₄ (NS/QD) was produced from bulk g-C₃N₄. To improve electrocatalytic hydrogen evolution reaction (HER), the g-C₃N₄ (NS/QD) were modified by the MoS₂ nanostructures. Nanocomposite of the g-C₃N₄ (NS/QD) with MoS₂ nanostructures was deposited on a flexible, conductive and three dimensional carbon cloth by a facile and binder-free electrophoretic technique. This electrode exhibited a Tafel slope of 88 mV/dec and an overpotential of 0.28 V vs RHE at −2 mA/cm², lower than that of the g-C₃N₄, and good stability after 1000 cycles and 100 days for HER. The enhanced electrocatalytic performance was attributed to the MoS₂ and g-C₃N₄ nanostructures on three dimensional carbon cloth, leading to high surface area and more number of the exposed active sites for HER. This heterostructure improved charge transport, proton adsorption and hydrogen evolution on the electrode. This work proposes cost-effective, stable and three dimensional g-C₃N₄ based electrode for hydrogen evolution reaction.     

Avoidance of partial load operation at coal-fired power plants by storing nuclear power through power to gas

The need of fast regulation of electricity production leads to a number of inconveniences occurred to the electric generation system and the electric market, especially to the nuclear power. A new concept to control nuclear power production is posed in order to allow the regulation of the electricity sent to the grid. This concept proposes the joint operation of a nuclear power plant, a coal power plant with postcombustion capture and a methanation plant. The cost effectiveness of this technology and its capability to reduce the CO₂ emissions -consumed in the methanation process- are assessed through the design and economic and environmental analysis of a hybrid facility. Mainly due to the increase of the operating hours of the coal-fired power plant, the environmental feasibility of the initial proposal seems to be limited. However, given that benefits are expected in the medium and long-term (2020–2030) for the Power to Gas facility, a future alternative use is proposed. The target of this new alternative configuration will be the storage of CO₂ together with the storage of renewable energy.     

Disabling partners in crime: Gold nanoparticles disrupt multicellular communications within the tumor microenvironment to inhibit ovarian tumor aggressiveness

The tumor microenvironment (TME) plays a key role in the poor prognosis of many cancers. However, there is a knowledge gap concerning how multicellular communication among the critical players within the TME contributes to such poor outcomes. Using epithelial ovarian cancer (EOC) as a model, we show how crosstalk among cancer cells (CC), cancer associated fibroblasts (CAF), and endothelial cells (EC) promotes EOC growth. We demonstrate here that co-culturing CC with CAF and EC promotes CC proliferation, migration, and invasion in vitro and that co-implantation of the three cell types facilitates tumor growth in vivo. We further demonstrate that disruption of this multicellular crosstalk using gold nanoparticles (GNP) inhibits these pro-tumorigenic phenotypes in vitro as well as tumor growth in vivo. Mechanistically, GNP treatment reduces expression of several tumor-promoting cytokines and growth factors, resulting in inhibition of MAPK and PI3K-AKT activation and epithelial-mesenchymal transition - three key oncogenic signaling pathways responsible for the aggressiveness of EOC. The current work highlights the importance of multicellular crosstalk within the TME and its role for the aggressive nature of EOC, and demonstrates the disruption of these multicellular communications by self-therapeutic GNP, thus providing new avenues to interrogate the crosstalk and identify key perpetrators responsible for poor prognosis of this intractable malignancy.     

FeCo nanocrystals encapsulated in N-doped carbon nanospheres/thermal reduced graphene oxide hybrids: Facile synthesis,magnetic and catalytic properties

The hybrids of FeCo nanocrystals encapsulated in N-doped carbon nanospheres (FeCo–NCNS) supported on thermal reduced graphene oxide (FeCo–NCNS/TRGO) are synthesized by in situ growth of Co₂Fe(CN)₆ onto graphene oxide (GO), followed with a subsequent pyrolysis process. The as-synthesized products are characterized by transmission electron microscopy, powder X-ray diffraction, Raman spectroscopy, elements analysis and inductively coupled plasma optical emission spectrometer. The hybrids exhibit excellent ferromagnetic behavior, superior electrocatalytic activity toward oxygen reduction reaction (ORR), and markedly enhanced catalytic activity toward the reduction of 4-nitrophenol (4-NP) by NaBH₄, which make the hybrids be attractive materials for various potential applications. Moreover, the performance of the hybrids can be optimized through adjusting the content of FeCo–NCNS on thermal reduced graphene oxide. This novel and elegant method presented here could be extended to synthesize other metal/alloy-NCNS/TRGO hybrids with various functions.