Encapsulation of Noble Metal Nanoparticles through Seeded Emulsion Polymerization as Highly Stable Plasmonic Systems

The implementation of plasmonic nanoparticles in vivo remains hindered by important limitations such as biocompatibility, solubility in biological fluids, and physiological stability. A general and versatile protocol is presented, based on seeded emulsion polymerization, for the controlled encapsulation of gold and silver nanoparticles. This procedure enables the encapsulation of single nanoparticles as well as nanoparticle clusters inside a protecting polymer shell. Specifically, the efficient coating of nanoparticles of both metals is demonstrated, with final dimensions ranging between 50 and 200 nm, i.e., sizes of interest for bio‐applications. Such hybrid nanocomposites display extraordinary stability in high ionic strength and oxidizing environments, along with high cellular uptake, and low cytotoxicity. Overall, the prepared nanostructures are promising candidates for plasmonic applications under biologically relevant conditions.     

Recent Progress on Silica Coating of Nanoparticles and Related Nanomaterials

In recent years, new strategies for silica coating of inorganic nanoparticles and organic nanomaterials, which differ from the classical methodologies, have emerged at the forefront of materials science. Silica as a coating material promises an unparalleled opportunity for enhancement of colloidal properties and functions by using core–shell rational designs and profiting from its synthetic versatility. This contribution provides a brief overview of recent progress in the synthesis of silica‐coated nanomaterials and their significant impact in different areas such as spectroscopy, magnetism, catalysis, and biology.     

Preparation of colloidal Fe3O4 ultrafine particles in microemulsions

The preparation of magnetite particles is reported from the precipitation of Fe²⁺/Fe³⁺ with NH₄OH in several kinds of microemulsions: AOT/n-heptane/water microemulsions and a new non-toxic microemulsion system whose phase behaviour and structure has been recently studied. It is shown that both the droplet size and the presence of interactions in the dispersed phase greatly influence the final size of the obtained particles. In addition, the size of the particles can be increased by successive repetition of the reaction inside the droplets of the microemulsion.     

Core-level shift analysis of amorphous CdTeOx materials

We show the importance of considering the detailed local distributions of oxygen atoms around tellurium in CdTeO _x glasses when interpreting X-ray photoemission experiments. We perform first principles calculations of core-level shifts that are used to compute X-ray photo-electron spectra. The core-level shifts are investigated by means of atomic density of states and a structural Voronoi analysis. We find that the dominating effect on the atomic core-level shift of tellurium is charge redistribution due to the oxygen atoms. There is however also a prominent effect from the geometrical arrangement of the oxygen neighbors.     

Nonlinear homogenization techniques to solve masonry structures problems

The behaviour of masonry material subjected to different in-plane loading combination is studied in this work. The masonry is considered as a periodic composite material composed by a regular distribution of brick and mortar and it is analyzed using a homogenization technique. The mechanical properties of the masonry, as an orthotropic homogeneous material, depend on the geometrical and mechanical properties of the components based on the study of the equilibrium and compatibility of a basic cell. The masonry is a frictional material and its behaviour depends on the loading direction, for these reasons, a unilateral damage model is chosen for the analysis. This model describes the behaviour of brittle materials subjected to tension-compression cyclic loads based on the introduction of two damage variables and it assumes that the damage is due to the beginning and growth of cracks only in the mortar joints. It is considered that the bricks have a linear elastic constitutive relationship. Numerical applications are performed with a nonlinear finite element code in order to test the proposed procedure by comparing the results with those available in the literature and also with experimental data.     

Encapsulation of Single Plasmonic Nanoparticles within ZIF‐8 and SERS Analysis of the MOF Flexibility

Hybrid nanostructures composed of metal nanoparticles and metal‐organic frameworks (MOFs) have recently received increasing attention toward various applications due to the combination of optical and catalytic properties of nanometals with the large internal surface area, tunable crystal porosity and unique chemical properties of MOFs. Encapsulation of metal nanoparticles of well‐defined shapes into porous MOFs in a core–shell type configuration can thus lead to enhanced stability and selectivity in applications such as sensing or catalysis. In this study, the encapsulation of single noble metal nanoparticles with arbitrary shapes within zeolitic imidazolate‐based metal organic frameworks (ZIF‐8) is demonstrated. The synthetic strategy is based on the enhanced interaction between ZIF‐8 nanocrystals and metal nanoparticle surfaces covered by quaternary ammonium surfactants. High resolution electron microscopy and tomography confirm a complete core–shell morphology. Such a well‐defined morphology allowed us to study the transport of guest molecules through the ZIF‐8 porous shell by means of surface‐enhanced Raman scattering by the metal cores. The results demonstrate that even molecules larger than the ZIF‐8 aperture and pore size may be able to diffuse through the framework and reach the metal core.     

Effect of chronic growth hormone administration on diabetic nephropathy in the rat

Indirect data exist which implicate elevated growth hormone (GH) as a factor in the development of diabetic nephropathy. The administration of somatostatin (SRIH) has been shown to reverse many of the changes found in early diabetic nephropathy; however, it is unknown whether SRIH causes these effects by the suppression of GH or by other unspecified factors. To study directly the possible effect of excess GH in the development of diabetic nephropathy, either ovine growth hormone (0.2 mg oGH) or diluent buffer was administered IM daily for 19 weeks to diabetic rats and to controls. Severity of nephropathy was assessed by 24 hour urine albumin excretion (UAE), relative kidney weight, and kidney histology. Results showed that diabetic rats overall had elevated UAE and kidney weight vs non-diabetic rats (46.2 +/- 8.6 vs 5.4 +/- 1.3 mg per day and 5.7 +/- 0.2 vs 2.7 +/- 0.1 mg per g of body weight, respectively, p < 0.001). However, no differences were detected between diabetic rats treated with GH compared to control diabetic rats. Additionally, diabetic rats had histopathologic changes consistent with early diabetic nephropathy, but no difference in severity scores was found between diabetic groups. These data provide evidence against GH as an etiologic factor in the development of diabetic nephropathy and it is speculated by the authors that SRIH exerts its protective renal effects in diabetes by mechanisms other than GH suppression.     

An empirical study of interest-based negotiation

While argumentation-based negotiation has been accepted as a promising alternative to game-theoretic or heuristic-based negotiation, no evidence has been provided to confirm this theoretical advantage. We propose a model of bilateral negotiation extending a simple monotonic concession protocol by allowing the agents to exchange information about their underlying interests and possible alternatives to achieve them during the negotiation. We present an empirical study that demonstrates (through simulation) the advantages of this interest-based negotiation approach over the more classic monotonic concession approach to negotiation.     

An enriched macro finite element for the static analysis of thick general quadrilateral laminated composite plates

This article presents the formulation of an enriched macro finite element based on the trigonometric shear deformation theory for the static analysis of symmetrically laminated composite plates. Shear correction factor is not required because this theory accounts for tangential stress-free boundary conditions on the plate boundary surfaces. The macro element is obtained using the principle of virtual work and Gram-Schmidt orthogonal polynomials as enrichment functions. The implementation of the obtained algorithm is simple and efficient, and allows studying general quadrilateral plates with a single macro element. Several examples are presented to show the capability and applicability of the developed formulation.