Non-hemolytic α-AApeptides as antimicrobial peptidomimetics

We report a new class of peptide mimetics, α-AApeptides, that display broad-spectrum activity against both Gram-negative and Gram-positive bacteria and fungi. With non-hemolytic activity, resistance to protease hydrolysis, and easy sequence programmability, α-AApeptides may emerge as a novel class of antibiotics.     

Bismuth-Based Halide Perovskites for Photocatalytic H2 Evolution Application

Metal halide perovskites (MHPs), in particular lead-based perovskites, have earned recognized fame in several fields for their outstanding optoelectronic properties, including direct generation of free charge carriers, optimal ambipolar charge carrier transport properties, high absorption coefficient, point-defect tolerance, and compositional versatility. Nowadays, this class of materials represents a real and promising alternative to silicon for photovoltaic technologies. This worthy success led to a growing interest in the exploration of MHPs in other hot research fields, such as solar-driven photocatalytic water splitting towards hydrogen production. Nevertheless, many of these perovskites show air and moisture instability problems that considerably hinder their practical application for photocatalytic water splitting. Moreover, if chemical instability is a problem that can be in part mitigated by the optimization of the chemical composition and crystal structure, the presence of lead represents a real problem for the practical application of MHPs in commercial devices due to environmental and healthcare issues. To successfully overcome these problems, lead-free metal halide perovskites (LFMHPs) have gained increasing interest thanks to their optoelectronic properties, comparable to lead-based materials, and their more eco-friendly nature. Among all the lead-free perovskite alternatives, this mini-review considers bismuth-based perovskites and perovskite derivatives with a specific focus on solar-driven photocatalysis application for H₂ evolution. Special attention is dedicated to the structure and composition of the different materials and to the advantage of heterojunction engineering and the relative impact on the photocatalytic process.     

Frequency and temperature dependence of a.c. conductivity of vitreous silver phosphate electrolytes

The a.c. conductivity behaviour in the 20–300 K temperature range has been investigated for (Ag₂S)_x(AgPO₃)_1−x and (Ag₂SO₄)_x(AgPO₃)_1−x glasses at various salt contents (x). The temperature dependence at selected frequencies in the radioand micro-wave region displays several relaxational contributions which are indistinct in the frequency domain. The low temperature experimental data are discussed and a proposed ‘new universality’ has been examined.     

Pd8Ni92(1 1 0) surface structure from surface X-ray diffraction. Surface evolution under hydrogen and butadiene reactants at elevated pressure

The (N × 1) reconstruction (N = 5-6) of the clean Pd₈Ni₉₂(1 1 0) surface has been investigated by surface X-ray diffraction. A good fit with experimental data collected under UHV conditions is obtained when introducing undulations in the outer dense rows, constituted mainly of Pd atoms which strongly segregate to the surface. This reconstruction can be regarded as a way to relax the strains induced on the bigger Pd surface atoms, at least partially. The modifications of the surface were studied under butadiene then hydrogen as well as during butadiene hydrogenation at elevated pressure at 300 K and the (N × 1) reconstruction was found to be still present. The main changes are observed under pure hydrogen and during butadiene hydrogenation.     

Tuning the shape of nanoparticles to control their catalytic properties: selective hydrogenation of 1,3-butadiene on Pd/Al2O3

Shape-controlled Pd nanoparticles supported on powder alumina are more efficient for selective butadiene hydrogenation to butene when they exhibit high fractions of (111) facets.     

Synthesis and coating of cobalt ferrite nanoparticles: a first step toward the obtainment of new magnetic nanocarriers

Monodisperse and stable cobalt ferrite (CoFe2O4) nanoparticles (5.4 nm) have been produced, coated with mono- and difunctional phosphonic and hydroxamic acids, and fully characterized (using thermogravimetric analysis (TGA), dynamic light scattering (DLS), IR spectroscopy, transmission electron microscopy (TEM), and superconducting quantum interference device (SQUID) measurements). Cobalt leakage of the coated nanoparticles has been also studied. Magnetic measurements show the possible applications in hyperthermia at low frequencies, and for this reason, water-soluble coated CoFe2O4 can be seen as a first step toward the obtainment of novel systems for biomagnetic applications.     

Kinetics of the C2H2 dissociation on Ni(111): A HREELS study

The C₂H₂ isothermal dissociation rate on Ni(111) was measured by following, with HREEL spectroscopy, the intensity of the CH stretching peak as a function of time. By repeating the experiment at several different temperatures we have obtained an activation energy of 1.2 ± 0.1 eV/molecule and a pre-exponential factor of 10^14±1 s⁻¹ for the first step of the C₂H₂ dissociation reaction.