Cyclic and polyphosphazenes are extremely interesting and versatile substrates characterized by the presence of -P=N- repeating units. The chlorine atoms on the P atoms in the starting materials can ...be easily substituted with a variety of organic substituents, thus giving rise to a huge number of new materials for industrial applications. Their properties can be designed considering the number of repetitive units and the nature of the substituent groups, opening up to a number of peculiar properties, including the ability to give rise to supramolecular arrangements. We focused our attention on the extensive scientific literature concerning their biomedical applications: as antimicrobial agents in drug delivery, as immunoadjuvants in tissue engineering, in innovative anticancer therapies, and treatments for cardiovascular diseases. The promising perspectives for their biomedical use rise from the opportunity to combine the benefits of the inorganic backbone and the wide variety of organic side groups that can lead to the formation of nanoparticles, polymersomes, or scaffolds for cell proliferation. In this review, some aspects of the preparation of phosphazene-based systems and their characterization, together with some of the most relevant chemical strategies to obtain biomaterials, have been described.
Three different waste animal fats (bone, chicken, and tallow) have been studied to evaluate whether they could be used as bioliquids according to the European Regulation (EC) No.1069/2009. The ...analyses showed that they contained an unsuitable amount of free fatty acids (FFA) and impurities content (total sediment) if compared with the standards for power generation (set by UNI 6579:2009), with the exception of tallow fat (class C, UNI/TS 11163:2018). A series of physical-chemical processes already applied at industrial scale have been considered to manage the acid value and the impurities content. The FFA esterification was carried out with methanol, comparing two acid catalysts (sulfuric acid or Amberlyst – 15), followed by neutralization of the residual acidity with two different bases (ammonia solution or solid sodium carbonate monohydrate) when necessary. The final purification has been achieved by treatment with powdered activated carbon. In particular, the bone fat was studied as reference material, having the worst initial physical-chemical characteristics. The UNI/TS 11163:2018 standard would allow to classify the bioliquid from bone fat belonging to class B, while the one from chicken would require further degumming and purification processes to reduce the metals, sulfur, and phosphorus content.
In the framework of the circular economy, spent coffee grounds were converted into powdered activated carbon by means of pyrolysis, using potassium hydroxide as the activating agent. Its adsorption ...capacity on a panel of phenolic compounds was compared with those of two commercial powdered activated carbons, after preliminary studies on organic dyes with different ionic properties, to assess the affinity between adsorbates and adsorbents. Pseudo-first-order and pseudo-second-order kinetic models were carried out, together with Freundlich and Langmuir isotherms. They were useful to calculate the breakthrough at 5%, 10%, and 50% of adsorption and the partition coefficients for the comparison of performance between different sorbent systems in a less biased manner (e.g., reducing bias associated with operational settings like sorbate concentration and sorbents dosage). The results showed that the removal efficiency for SCGs-AC was comparable with that of the commercial activated carbons with the highest partition coefficients for methylene blue (12,455 mg/g/μM, adsorption capacity = 179 mg/g) and 3-chlorophenol (81.53 mg/g/μM, adsorption capacity = 3765 mg/g). The lower efficiency in bromothymol blue and bisphenol-A adsorption was due to its different morphology and surface properties.
The addition of magnetic particles to inorganic matrices can produce new composites exhibiting intriguing properties for practical applications. It has been previously reported that the addition of ...magnetite to concrete improves its mechanical properties and durability in terms of water and chloride ions absorption. Here we describe the preparation of novel magnetic geopolymers based on two different matrices (G1 without inert aggregates and G2 with inert quartz aggregates) containing commercial SrFe
O
particles with two weight concentrations, 6% and 11%. The composites' characterization, including chemical, structural, morphological, and mechanical determinations together with magnetic and electrical measurements, was carried out. The magnetic study revealed that, on average, the SrFe
O
magnetic particles can be relatively well dispersed in the inorganic matrix. A substantial increase in the composite samples' remanent magnetization was obtained by embedding in the geopolymer SrFe
O
anisotropic particles at a high concentration under the action of an external magnetic field during the solidification process. The new composites exhibit good mechanical properties (as compressive strength), higher than those reported for high weight concretes bearing a similar content of magnetite. The impedance measurements indicate that the electrical resistance is mainly controlled by the matrix's chemical composition and can be used to evaluate the geopolymerization degree.
Three new 6-methyl-2-oxo-1,2-dihydroquinoline-3-carbaldehyde-thiosemicarbazones-N-4-substituted pro-ligands and their Cu(II) complexes (
, -NH
;
, -NHMe;
, -NHEt) have been prepared and ...characterized. In both the X-ray structures of
and
, two crystallographically independent complex molecules were found that differ either in the nature of weakly metal-binding species (water in
and nitrate in
) or in the co-ligand (water in
and methanol in
). Electron Paramagnetic Resonance (EPR) measurements carried out on complexes
and
confirmed the presence of such different species in the solution. The electrochemical behavior of the pro-ligands and of the complexes was investigated, as well as their biological activity. Complexes
and
exhibited a high cytotoxicity against human tumor cells and 3D spheroids derived from solid tumors, related to the high cellular uptake. Complexes
and
also showed a high selectivity towards cancerous cell lines with respect to non-cancerous cell lines and were able to circumvent cisplatin resistance. Via the Transmission Electron Microscopy (TEM) imaging technique, preliminary insights into the biological activity of copper complexes were obtained.
The paper aims to compare different methods able to estimate the specific loss power (SLP) generated by three different types of magnetic nanoparticles, MNPs, dispersed in a suspension fluid, e.g., ...octane or water. The nanoparticles were characterized morphologically in terms of shape and size, chemically for composition and their physical properties like magnetization and SLP were studied. We evidenced the differences in SLP evaluation due to the applied method, particularly in the presence of thermally induced phenomena such as aggregation or precipitation of MNPs that can affect the heating curve of the samples. Then, the SLP determination methods less sensible to this phenomenon appear to be the ones that use the initial slope when the sample is in quasi-adiabatic condition. Finally, we propose a comparison of those methods based on the pros and cons of their use for the SLP determination of magnetic nanofluids. In particular, the analysis of the behavior of the heating curve is useful to evaluate the useful amplitude of the interval analysis for the initial slope methods.
Massive quantities of spent coffee grounds (SCGs) are generated by users around the world. Different processes have been proposed for SCG valorization, including pyrolytic processes to achieve ...carbonaceous materials. Here, we report the preparation of activated carbons through pyrolytic processes carried out under different experimental conditions and in the presence of various porosity activators. Textural and chemical characterization of the obtained carbons have been achieved through Brunauer–Emmett–Teller (BET), ESEM, 13C solid state NMR, XPS, XRD, thermogravimetric and spectroscopic determinations. The aim of the paper is to relate these data to the preparation method, evaluating the correlation between the spectroscopic data and the physical and textural properties, also in comparison with the corresponding data obtained for three commercial activated carbons used in industrial adsorption processes. Some correlations have been observed between the Raman and XPS data.
The reaction chemistry of nitriles, RCN, where R is usually an organyl group, with transition metal complexes is reviewed. The review surveys data published during the period 1977-early 1994 on new ...reaction processes such as insertion into metal-hydrogen and -carbon bonds, coupling between one nitrile and an unsaturated metal fragment or between two nitriles, reduction to amines, attack by protic and aprotic nucleophiles and electrophilic attack as well as some catalytic transformations, which result from the ability of nitriles to coordinate to transition metal centres with a consequent change in the electrophilicity or nucleophilicity of the coordinated ligand.
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