Surfactant-free nonaqueous synthesis of metal oxide nanostructures

Surfactant-free nonaqueous (and/or nonhydrolytic) sol-gel routes constitute one of the most versatile and powerful synthesis methodologies for nanocrystalline metal oxides with high compositional homogeneity and purity. Although the synthesis protocols are particularly simple, involving only metal oxide precursors and common organic solvents, the obtained uniform nanocrystals exhibit an immense variety of sizes and shapes. The small number of reactants in these routes enables the study of the chemical mechanisms involved in metal oxide formation. Nonhydrolytic routes to inorganic nanomaterials that used surfactants as size- and shape-controlling agents have been discussed recently. This Minireview supplements this topic by discussing surfactant-free processes, which have become a valuable alternative to surfactant-assisted as well as to traditional aqueous sol-gel chemistry routes.     

A Universal Synthesis Strategy for Tunable Metal-Organic Framework Nanohybrids**

Metal-organic frameworks (MOFs) with encapsulated nanoparticles (NPs) enjoy a vastly expanded application potential in catalysis, filtration, and sensing. The selection of particular modified core-NPs has yielded partial successes in overcoming lattice mismatch. However, restrictions on the choice of NPs not only limit the diversity, but also affect the properties of the hybrid materials. Here, we show a versatile synthesis strategy using a representative set of seven MOF-shells and six NP-cores that are fine-tuned to incorporate from single to hundreds of cores in mono-, bi-, tri- and quaternary composites. This method does not require the presence of any specific surface structures or functionalities on the pre-formed cores. Our key point is to regulate the diffusion rate of alkaline vapors that deprotonate organic linkers and trigger the controlled MOF-growth and encapsulation of NPs. This strategy is expected to pave the way for the exploration of more sophisticated MOF-nanohybrids.     

Point-of-Care Testing for the Detection of MicroRNAs: Towards Liquid Biopsy on a Chip

Point-of-care (PoC) testing is revolutionizing the healthcare sector improving patient care in daily hospital practice and allowing reaching even remote geographical areas. In the frame of cancer management, the design and validation of PoC enabling the non-invasive, rapid detection of cancer markers is urgently required to implement liquid biopsy in clinical practice. Therefore, focusing on stable blood-based markers with high-specificity, such as microRNAs, is of crucial importance. In this work, we highlight the potential impact of circulating microRNAs detection on cancer management and the crucial role of PoC testing devices, especially for low-income countries. A detailed discussion about the challenges that should be faced to promote the technological transfer and clinical use of these tools has been added, to provide the readers with a complete overview of potentialities and current limitations.     

Gas-Free Amino- and Alkoxycarbonylation of Aryl Iodides in a Bioinspired Deep Eutectic Solvent with Mo(CO)6 as a Safe CO Source

The Pd-catalyzed amino- and alkoxycarbonylation of aryl iodides has been exploited, for the first time, in a bioinspired Deep Eutectic Solvent and under gas-free conditions, by using Mo(CO)₆ as the CO source. The method allows for the preparation of carboxylic amides and esters in high yields (up to 99 %), short reaction time (2 h) and under mild reaction conditions (80 °C), with a low catalyst loading (2.5 mol %). Noteworthy, in the case of N-hexylbenzamide, it has been demonstrated that both the catalyst and DES can be used for four consecutive runs, with a moderate decrease of catalytic efficiency. The methodology has been also applied to the preparation of an Active Pharmaceutical Ingredient used for the treatment of human scabies and lice.     

Optimization of Mn-Mg-Al Mixed Oxides Composition on their Activity towards the Total Oxidation of Aromatic and Oxygenated VOCs

A series of mixed oxides (Mn-Mg-Al) is prepared by coprecipitation via a hydrotalcite route with different manganese ratios. Structural, textural, and redox properties are studied by XRD, N₂-sorption, H₂-TPR, and XPS techniques. Mn_xMg_6-xAl₂-O mixed oxides (with 0≤x≤6) are tested in the total oxidation of ethanol and toluene, two probe molecules representing respectively oxygenated and aromatic VOCs. Catalysts with higher manganese contents have shown the best catalytic performance for the oxidation of both ethanol and toluene. The surface activity of the materials is mainly related to the presence of manganese species in three different oxidation states (+II, +III, and +IV) in the bulk and on the material's surface. Since high Mn-content catalysts showed similar physicochemical properties and catalytic activity, Mn₄Mg₂-O is selected as the optimal composition of these materials. Furthermore, its aging test is compared to that of noble metal-based commercial catalysts (Pd/γ-Al₂O₃).     

Formation and Surface Behavior of Pt and Pd Complexes with Ligand Systems Derived from Nitrile-functionalized Ionic Liquids Studied by XPS

We studied the formation and surface behavior of Pt(II) and Pd(II) complexes with ligand systems derived from two nitrile-functionalized ionic liquids (ILs) in solution using angle-resolved X-ray photoelectron spectroscopy (ARXPS). These ligand systems enabled a high solubility of the metal complexes in IL solution. The complexes were prepared by simple ligand substitution under vacuum conditions in defined excess of the coordinating ILs, [C₃CNC₁Im][Tf₂N] and [C₁CNC₁Pip][Tf₂N], to immediately yield solutions of the final products. The ILs differ in the cationic head group and the chain length of the functionalized substituent. Our XPS measurements on the neat ILs gave insights in the electronic properties of the coordinating substituents revealing differences in donation capability and stability of the complexes. Investigations on the composition of the outermost surface layers using ARXPS revealed no surface affinity of the nitrile-functionalized chains in the neat ILs. Solutions of the formed complexes in the nitrile ILs showed homogeneous distribution of the solute at the surface with the heterocyclic moieties preferentially orientated towards the vacuum, while the metal centers are rather located further away from the IL/vacuum interface.     

Almost Diagonalization of $$tau $$ τ -Pseudodifferential Operators with Symbols in Wiener Amalgam and Modulation Spaces

Journal of Fourier Analysis and Applications - In this paper we focus on the almost-diagonalization properties of $$tau $$ -pseudodifferential operators using techniques from time-frequency...     

A loss network model with overflow for capacity planning of a neonatal unit

The main aim of this paper is to derive a solution to the capacity problem faced by many perinatal networks in the United Kingdom. We propose a queueing model to determine the number of cots at all care units for any desired overflow and rejection probability in a neonatal unit. The model formulation is developed, being motivated by overflow models in telecommunication systems. Exact expressions for the overflow and rejection probabilities are derived. The model is then applied to a neonatal unit of a perinatal network in the UK.     

Generalized minimizing movements for the mean curvature flow with Dirichlet boundary condition

We study a variational approach, called Generalized Minimizing Movemenents (GMM) and proposed by E. De Giorgi, to evolution of hypersurfaces by mean curvature in the case of a Dirichlet boundary datum. We prove an existence theorem of a GMM when on the initial solid are made suitable geometric hypotheses.

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Sunto Si studia un approccio variazionale, detto Movimenti Minimizzanti Generalizzati (GMM) e proposto da Ennio De Giorgi, per l’evoluzione di una ipersuperficie secondo la curvatura media con un dato al bordo di tipo Dirichlet. Viene provato un teorema di esistenza quando sul solido iniziale siano fatte opportune ipotesi di tipo geometrico.

     

A variational approach to mean curvature flow with Dirichlet conditions

We study a variational approach, called Generalized Minimizing Movements (GMM), to evolution of hypersurfaces by mean curvature in the case of a Dirichlet boundary datum. We prove an existence theorem of a GMM when on the initial solid are made suitable geometric hypotheses.

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Sunto In questo lavoro studiamo un approccio variazionale, detto Movimenti Minimizzanti Generalizzati (GMM), all’evoluzione di ipersuperfici per curvatura media nel caso di dato al bordo di Dirichlet. Dimostriamo un teorema di esistenza per un GMM quando vengono assunte ipotesi opportune sul solido iniziale.