Application of a new Structural Joint Inversion Approach to Teleseismic and Gravity Data from Mt.Vesuvius, Italy

A 3-D joint inversion of seismic and gravimetric data is performed to re-investigate the subsurface structure of Mt. Vesuvius (Italy) utilizing an improved joint inversion method. The aim is to derive models of the 3D distribution of velocity and density perturbations that are consistent with both data sets and with local velocity models. Mt. Vesuvius is a strato volcano located within a graben (Campania Plain) formed in Plio-Pleistocene. Campania Plain is bordered by mostly Mesozoic carbonaceous rocks. Mt. Vesuvius is the southernmost and the youngest of a group of Pleistocene volcanoes, three of which (Ischia, Campi Flegrei and Mt. Vesuvius) have erupted in historical times. The most recent eruption of Mt. Vesuvius occurred in 1944 and since then the volcanic activity has been characterized by moderate low magnitude seismicity and low temperature fumaroles at the summit crater. We modified the coupling mechanism between velocity and density models in the JI-3D optimized joint inversion method (Jordan and Achauer, 1999). This method was designed to provide stable and high resolution results and involves iterative optimized parameterization, 3D ray tracing, and the incorporation of a priori information. The coupling of the velocity and density models, vital to the joint inversion, is based on a cross-gradient approach (e.g. Gallardo and Meju, 2004), which has been proven to work very well in a variety of cases involving seismic, magnetic, CSEM, MT and gravity data sets. We implemented the cross-gradient coupling for our 3-D irregular adaptive grid parameterization. In contrast to conventional joint inversion methods this approach encourages structural similarities in the models and does not rely on predefined relationships between velocity and density parameters. As a consequence, the resulting velocity-density relations are not contaminated by a priori assumptions and can be utilized to derive rock physical parameters. We apply this method to data from the TomoVes project (Gasparini et al. 1998), combining seismics and Bouguer gravity and local high resolution velocity models as a priori information. The starting models for the joint inversion are derived by separate inversions of the individual data sets. We show 3D distributions of velocity perturbations and density variations from the joint inversion of teleseismic relative traveltimes and Bouguer anomaly data with the aim of extracting further information about the physical status of the volcano- tectonic system

General Route to High Surface Area Covalent Organic Frameworks and Their Metal Oxide Composites as Magnetically Recoverable Adsorbents and for Energy Storage

Two-dimensional (2D) imine-linked covalent organic frameworks (COFs) have attracted great interest for gas uptake, catalysis, drug delivery, electronic devices, and photocatalytic applications. The synthetic methodologies involved in imine-linked COF formations such as solvothermal synthesis usually require harsh experimental conditions. In this work, we show for the first time how highly crystalline COFs with very high surface areas (3.6 times higher than using conventional approaches) can be prepared by combining a mechanochemical and crystallization approach. More importantly, this facile method is a general route to novel composites of COF and metal oxides including Fe₃O₄, Co₃O₄, and NiO. The composites can be used as magnetically recoverable adsorbents and show a strong redox-activity making them interesting for applications in electrochemical energy storage

A Sustainable Template for Mesoporous Zeolite Synthesis

A generalized synthesis of high-quality, mesoporous zeolite (e.g., MFI-type) nanocrystals is presented, based on a biomass-derived, monolithic N-doped carbonaceous template. As an example, ZSM-5 single crystals with desirable large-diameter (12–16 nm) intracrystalline mesopores are synthesized. The platform provides scope to optimize template dimensions and chemistry for the synthesis of a range of micro-/mesoporous crystalline zeolites in a cost-effective and highly flexible manner

Light-Switchable Polymers of Intrinsic Microporosity

The interest in (micro)­porous systems is greater than ever before with microporous polymers finding application in areas such as gas storage/separation and catalysis. In contrast to the vast majority of publications on microporous polymers seeking ever higher values for surface area or uptake capacity for a particular gas, this work presents a means to render a microporous system responsive to electromagnetic stimuli. The incorporation of a diarylethene (DAE) derivative in the backbone of a polymer of intrinsic microporosity (PIM) produces a microporous system that exhibits photochromism as proven by UV–vis absorption and NMR studies. In the resulting DAE-PIM, surface area is not a fixed unalterable property but can be influenced by the external and nondestructive stimulus light in a reversible manner. Furthermore, in combination with Matrimid, free-standing membranes can be produced that display light-switchable diffusivity and permeability for carbon dioxide and oxygen. In this way, material scientists are offered the potential to employ only one system that can assume several states with different properties for each

Covalent Triazine Frameworks Prepared from 1,3,5-Tricyanobenzene

A novel covalent triazine framework (CTF-0) was prepared by trimerization of 1,3,5-tricyanobenzene in molten ZnCl₂. The monomer/ZnCl₂ ratio, the reaction time, and temperature significantly influence the structure and porosity of such networks. XRD measurements revealed that crystalline frameworks can be formed with surface areas around 500 m²·g^–1 and high CO₂ uptakes. Increasing the reaction temperature yielded an amorphous material with an enlarged surface area of 2000 m²·g^–1. This material showed good catalytic activity for CO₂ cycloaddition

One-Pot Synthesis of Supported, Nanocrystalline Nickel Manganese Oxide for Dry Reforming of Methane

Silica supported nanoparticles of nickel manganese oxide, Ni_0.2Mn_0.8O, were prepared in a one-pot approach, combining co-precipitation and sol–gel chemistry. This approach enables the preparation of small ternary oxide crystallites evenly dispersed on porous silica. The resulting materials were used as catalyst for dry reforming of methane (DRM), and show a much higher activity as the reference bulk material prepared from conventional co-precipitation. Notably, the catalyst shows a remarkable activity even at low temperatures for DRM, thus nearly reaching thermodynamic equilibrium at 500 °C

Ionic Liquid-Assisted Synthesis of Mesoporous Carbons with Surface-Enriched Nitrogen for the Hydrogen Evolution Reaction

Heteroatom-doped carbon materials are promising metal-free catalysts for the hydrogen evolution reaction (HER) at low voltage with high durability. However, many of the active sites introduced by heteroatom doping are hardly accessible within the bulk carbon structure and consequently contribute little to the catalytic activity. Here we report a facile ionic liquid-assisted method for synthesizing mesoporous nitrogen-doped carbons, enabling enrichment of nitrogen atoms at the pore surface, demonstrated by X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption of carbon dioxide (CO₂-TPD). The resulting metal-free nitrogen-doped mesoporous carbons exhibit a remarkable electrocatalytic activity in HER. The accessible and efficient utilization of nitrogen atoms is responsible for the superior HER catalytic activity

Microporous Thioxanthone Polymers as Heterogeneous Photoinitiators for Visible Light Induced Free Radical and Cationic Polymerizations

Conjugated microporous polymeric networks possessing thioxanthone groups were reported to initiate free radical and cationic polymerizations of vinyl monomers and cyclic ethers, respectively, under visible light irradiation. These new classes of <i>Type II</i> macrophotoinitiators with high porosity having large BET surface area of 500–750 m² g^–1 were prepared through different cross-coupling processes. Polymerizations are successfully achieved in conjugation with several co-initiators benefiting from hydrogen abstraction or electron transfer reactions stimulated by either visible light or natural sunlight irradiation. Photopolymerizations conducted by using knitted photoinitiators show better conversion and rate of polymerization than those obtained via Sonogashira–Hagihara coupling. The heterogeneous nature of the photoinitiators makes them easily separable from the media and more importantly reusable for further polymerizations while retaining the photocatalytic activity

Noble-Metal-Free Electrocatalysts with Enhanced ORR Performance by Task-Specific Functionalization of Carbon using Ionic Liquid Precursor Systems

The synthesis and characterization of functionalized carbon using variable doping profiles are presented. The hybrids were obtained from nitrile-functionalized ionic precursors and a ferric chloride mediator. This way, novel nitrogen doped and nitrogen–sulfur, nitrogen–phosphorus, and nitrogen–boron codoped carbon hybrids with a morphology containing microporous nanometer-sized particles were obtained. As-prepared heteroatom doped carbons exhibited superior electrocatalytic activity toward the oxygen reduction reaction (ORR) in alkaline and acid electrolytes. In particular, both the heteroatom type and iron were found to play crucial roles in improving the catalytic activity of functionalized carbon. It is worth noting that sulfur–nitrogen codoped functionalized materials synthesized in the presence of ferric chloride showed higher activity and stability in comparison to those of the commercial state-of-the-art Pt catalyst in alkaline electrolyte. Moreover, in acid electrolyte, sulfur–nitrogen codoped catalyst rivaled the activity of Pt with a stability outperforming that of Pt. Our X-ray photoelectron spectroscopy (XPS) investigation revealed a distinctive atomic structure in nitrogen–sulfur codoped material in comparison to other codoped catalysts, most likely explaining its superior electrocatalytic activity. This work presents a novel toolbox for designing advanced carbon hybrids with variable heteroatom doping profiles which presents tunable and enhanced ORR performance

3D Anionic Silicate Covalent Organic Framework with srs Topology

The synthesis of 3D covalent organic frameworks (COFs) adopting novel topologies is challenging, and so far 3D COFs have only been reported for nets based on building blocks with tetrahedral geometry. We demonstrate the targeted synthesis of an anionic 3D COF crystallizing in a three-coordinated <b>srs</b> net by exploiting a recently developed linkage for the formation of anionic silicate COFs based on hypercoordinate silicon nodes. The framework, named SiCOF-5, was synthesized by reticulating dianionic hexacoordinate [SiO₆]^2– nodes with triangular triphenylene building blocks and adopts a two-fold interpenetrated <b>srs-c</b> net with an overall composition of Na₂­[Si­(C₁₈H₆O₆)] (where C₁₈H₆O₆ is triphenylene-2,3,6,7,10,11-hexakis­(olate)). A key requirement for the crystallization of SiCOF-5 was the careful control over the nucleation and growth rate by gradual generation of the silicon source during the course of the reaction