Solid lipid nanoparticle (SLN), nanostructured lipid carriers (NLC) and hybrid nanoparticles, have gained increasing interest as drug delivery systems because of their potential to load and release ...drugs from the Biopharmaceutical classification system (BCS) of class II (low solubility and high permeability) and of class IV (low solubility and low permeability). Lipid properties (e.g. high solubilizing potential, biocompatibility, biotolerability, biodegradability and distinct route of absorption) contribute for the improvement of the bioavailability of these drugs for a set of administration routes. Their interest continues to grow, as translated by the number of patents being field worldwide. This paper discusses the recent advances on the use of SLN, NLC and lipid-polymer hybrid nanoparticles for the loading of lipophilic, poorly water-soluble and poorly permeable drugs, being developed for oral, topical, parenteral and ocular administration, also discussing the industrial applications of these systems. A review of the patents filled between 2014 and 2017, concerning the original inventions of lipid nanocarriers, is also provided.
Abstract
The set-up of the initial conditions in cosmological N-body simulations is usually implemented by rescaling the desired low-redshift linear power spectrum to the required starting redshift ...consistently with the Newtonian evolution of the simulation. The implementation of this practical solution requires more care in the context of massive neutrino cosmologies, mainly because of the non-trivial scale-dependence of the linear growth that characterizes these models. In this work, we consider a simple two-fluid, Newtonian approximation for cold dark matter and massive neutrinos perturbations that can reproduce the cold matter linear evolution predicted by Boltzmann codes such as camb or class with a 0.1 per cent accuracy or below for all redshift relevant to non-linear structure formation. We use this description, in the first place, to quantify the systematic errors induced by several approximations often assumed in numerical simulations, including the typical set-up of the initial conditions for massive neutrino cosmologies adopted in previous works. We then take advantage of the flexibility of this approach to rescale the late-time linear power spectra to the simulation initial redshift, in order to be as consistent as possible with the dynamics of the N-body code and the approximations it assumes. We implement our method in a public code (REPS rescaled power spectra for initial conditions with massive neutrinos https://github.com/matteozennaro/reps) providing the initial displacements and velocities for cold dark matter and neutrino particles that will allow accurate, i.e. 1 per cent level, numerical simulations for this cosmological scenario.
The use of layered perovskites is an important strategy to improve the stability of hybrid perovskite materials and their optoelectronic devices. However, tailoring their properties requires accurate ...structure determination at the atomic scale, which is a challenge for conventional diffraction-based techniques. We demonstrate the use of nuclear magnetic resonance (NMR) crystallography in determining the structure of layered hybrid perovskites for a mixed-spacer model composed of 2-phenylethylammonium (PEA+) and 2-(perfluorophenyl)ethylammonium (FEA+) moieties, revealing nanoscale phase segregation. Moreover, we illustrate the application of this structure in perovskite solar cells with power conversion efficiencies that exceed 21%, accompanied by enhanced operational stability.
We estimate the velocity field in a large set of N-body simulations including massive neutrino particles, and measure the auto-power spectrum of the velocity divergence field as well as the ...cross-power spectrum between the cold dark matter density and the velocity divergence. We perform these measurements at four different redshifts and within four different cosmological scenarios, covering a wide range in neutrino masses. We find that the nonlinear correction to the velocity power spectra largely depends on the degree of nonlinear evolution with no specific dependence on the value of neutrino mass. We provide a fitting formula based on the value of the rms of the matter fluctuations in spheres of 8 h−1 Mpc, describing the nonlinear corrections with 3% accuracy on scales below k = 0.7 h Mpc−1.
Layered hybrid perovskites based on Dion–Jacobson phases are of interest to various optoelectronic applications. However, the understanding of their structure–property relationships remains limited. ...Here, we present a systematic study of Dion–Jacobson perovskites based on (S)PbX4 (n = 1) compositions incorporating phenylene-derived aromatic spacers (S) with different anchoring alkylammonium groups and halides (X = I, Br). We focus our study on 1,4-phenylenediammonium (PDA), 1,4-phenylenedimethylammonium (PDMA), and 1,4-phenylenediethylammonium (PDEA) spacers. Systems based on PDA did not form a well-defined layered structure, showing the formation of a 1D structure instead, whereas the extension of the alkyl chains to PDMA and PDEA rendered them compatible with the formation of a layered structure, as shown by X-ray diffraction and solid-state NMR spectroscopy. In addition, the control of the spacer length affects optical properties and environmental stability, which is enhanced for longer alkyl chains and bromide compositions. This provides insights into their design for optoelectronic applications.
Silicene, the silicon equivalent of graphene, is attracting increasing scientific and technological attention in view of the exploitation of its exotic electronic properties. This novel material has ...been theoretically predicted to exist as a free-standing layer in a low-buckled, stable form, and can be synthesized by the deposition of Si on appropriate crystalline substrates. By employing low-energy electron diffraction and microscopy, we have studied the growth of Si on Ag(1 1 1) and observed a rich variety of rotationally non-equivalent silicene structures. Our results highlight a very complex formation diagram, reflecting the coexistence of different and nearly degenerate silicene phases, whose relative abundance can be controlled by varying the Si coverage and growth temperature. At variance with other studies, we find that the formation of single-phase silicene monolayers cannot be achieved on Ag(1 1 1).
Organic materials can tune the optical properties in layered (2D) hybrid perovskites, although their impact on photophysics is often overlooked. Here, we use transient absorption spectroscopy to ...probe the Dion–Jacobson (DJ) and Ruddlesden–Popper (RP) 2D perovskite phases. We show the formation of charge transfer excitons in DJ phases, resulting in a photoinduced Stark effect which is shown to be dependent on the spacer size. By using electroabsorption spectroscopy, we quantify the strength of the photoinduced electric field, while temperature-dependent measurements demonstrate new features in the transient spectra of RP phases at low temperatures resulting from the quantum-confined Stark effect. This study reveals the impact of spacer size and perovskite phase configuration on charge transfer excitons in 2D perovskites of interest to their advanced material design.
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► Polarized and spatially resolved NEXAFS spectra were acquired on ultra-thin free-standing graphene oxide (GO) membranes. ► TEM results show that GO membranes are prevalently made of ...separated phases, i.e. clean regions and oxidized ones alternating on a few-nm scale. ► Polarized NEXAFS measurements enabled identification of surface functional groups. ► We provide a new and efficient route to study the electronic structure of suspended membranes.
We have performed a near-edge X-ray absorption fine-structure (NEXAFS) and a transmission electron microscopy (TEM) investigation of freely suspended graphene oxide (GO) sheets. We utilized a photoemission electron microscope to identify GO membranes and to acquire C
K and O
K absorption spectra. The overall line shape of C
K-edge spectra demonstrates that the honeycomb carbon network of graphene is the scaffold of GO. However, the intensity ratio of
π
∗
and
σ
∗
resonances, and a broad feature at about 20
eV from the edge, indicate the presence of new carbon bonds. The O
K-edge spectra show that oxidized regions are made of carbonyl, epoxide, and hydroxyl groups attached to the plane of graphene, while carboxyl groups might also be present at the edges. Further, our study indicates the presence of ordered arrangements of oxygen atoms in GO sheets. Our investigation provides a new and efficient route to study the electronic structure of suspended membranes.
Abstract
The clustering ratio is defined as the ratio between the correlation function and the variance of the smoothed overdensity field. In Λ cold dark matter (ΛCDM) cosmologies without massive ...neutrinos, it has already been proven to be independent of bias and redshift space distortions on a range of linear scales. It therefore can provide us with a direct comparison of predictions (for matter in real space) against measurements (from galaxies in redshift space). In this paper we first extend the applicability of such properties to cosmologies that account for massive neutrinos, by performing tests against simulated data. We then investigate the constraining power of the clustering ratio on cosmological parameters such as the total neutrino mass and the equation of state of dark energy. We analyse the joint posterior distribution of the parameters that satisfy both measurements of the galaxy clustering ratio in the SDSS-DR12, and the angular power spectra of cosmic microwave background temperature and polarization anisotropies measured by the Planck satellite. We find the clustering ratio to be very sensitive to the CDM density parameter, but less sensitive to the total neutrino mass. We also forecast the constraining power the clustering ratio will achieve, predicting the amplitude of its errors with a Euclid-like galaxy survey. First we compute parameter forecasts using the Planck covariance matrix alone, then we add information from the clustering ratio. We find a significant improvement on the constraint of all considered parameters, and in particular an improvement of 40 per cent for the CDM density and 14 per cent for the total neutrino mass.
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