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Background: Traditional phosphorus fertilizers generally have low efficiencies due to their immobilization in soil, and a large part of these fertilizers are not plant-available. Also, phosphorus resources are non-renewable. In recent years, a great deal of attention has been paid to nanofertilizers because of their slow or controlled release and also their very small particle size which increases the solubility and uptake of nanoparticles in plant. Hydroxyapatite nanoparticles are of great importance as phosphorus nanofertilizer thanks to their very low toxicity, biocompatibility, and the fact that products obtained from their degradation, i.e., phosphate and calcium ions, are naturally available in soils. Results: In this study, hydroxyapatite nanoparticles were synthesized using the wet chemical precipitation method in three formulations and characterized with various techniques including electron microscopy, atomic force microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and elemental analysis. Chemical and microscopic analyses showed that phosphorus was distributed in different parts of the wheat (Triticum aestivum L.) plant. To investigate the fertilizing effects of the nanoparticles, hydroxyapatite nanoparticles were used in different culture media including alkaline soil, acidic soil, the mixture of peat moss and perlite, and cocopeat. Based on our observations, hydroxyapatite nanoparticles showed fertilizing properties in all media. However, fertilizing potential strongly depended on the culture media. HAP nanoparticles demonstrated a high potential to be used as a fertilizer in acidic media. Nevertheless, only a slight fertilizing effect was observed in alkaline soils. Furthermore, the findings of our study showed fertilizing properties of powder hydroxyapatite nanoparticles without the need to convert them to suspension. Moreover, hydroxyapatite nanoparticles in all the three formulations showed low toxicity in such a way that their toxicity was even less than that of triple super phosphate. Conclusions: Hydroxyapatite nanoparticles in both suspension and powder forms can be considered an alternative to conventional phosphorus fertilizers in acidic culture media. Our study revealed that hydroxyapatite nanoparticles were likely dissolved in the culture media and absorbed by plant mainly in the phosphate form. [ABSTRACT FROM AUTHOR]

In this research, ultrasonic synthesis is applied for the fabrication of a novel catalyst, based on immobilization of silver nanoparticles (AgNPs) on thiourea functionalized magnetic hydroxyapatite. A recoverable Ag nano-catalyst is constructed by decoration of AgNPs on the surface of thiourea modified magnetic hydroxyapatite. Magnetic hydroxyapatite is used as an organic–inorganic hybrid support for the catalyst. The organic–inorganic hybrid support is prepared by co-precipitation, followed by its surface modification through covalent functionalization of 1-(3,5-bis(trifluoromethyl)phenyl)-3-propyl)thiourea. The fabricated catalyst has been characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD), nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) analysis. The nanoparticles are mostly tubular in shape and their particle sizes are smaller than 100 nm. This nanocatalyst shows efficient and robust catalytic activity in different reactions, including selective reduction of 4-nitrophenol (4NP) and oxidation of primary amines by applying NaBH4 and urea hydrogen peroxide (UHP) as reagents, respectively. The catalyst shows good reusability in 10 sequential reaction runs. [ABSTRACT FROM AUTHOR]

Various monospiro-2-amino-4 H-pyran derivatives have been synthesized in high yields ( via three-component coupling of ninhydrin or different isatins with malononitrile and 1,3-dicarbonyl compounds) in the presence of catalytic amount of propane-1-sulfonic acid-modified magnetic hydroxyapatite nanoparticles in H2O. Due to easy magnetic removal of nanocatalyst and applying of H2O as solvent, this protocol enhanced product purity, and promised economic as well as environmental benefits, exemplifying a waste-free chemistry. More importantly, the catalyst could be easily recycled for more than five times without loss of activity. [ABSTRACT FROM AUTHOR]

Abstract: A novel magnetically recoverable silver nano-catalyst was fabricated by the adsorption–reduction of Ag (I) ions on the surface of hydroxyapatite encapsulated iron oxide nanoparticles. The magnetic catalyst could be easily separated by the application of an external magnetic field. The samples have been characterized by VSM, X-ray diffraction (XRD) and scanning and transmission electron microscopy (SEM and TEM), which reveal the superparamagnetic nano-nature of the particles. From these studies we can infer that the particles are mostly spherical in shape and have an average size of 10nm. The catalytic ability of the Ag nanoparticles supported on the magnetic nanocarier was found to be excellent and they cleanly oxidize primary amines to N-monoalkylated hydroxylamines. [Copyright &y& Elsevier]

Abstract: A highly efficient and green system is introduced to chemical synthesis. Magnetic nanoparticle-supported propylsulfamic acid deposited onto hydroxyapatite [γ-Fe2O3-HAp-(CH2)3-NHSO3H] synthesized as a unique heterogeneous acid catalyst of excellent activity and recyclable for at least 10 reaction runs without significant loss of activity. The facile recovery of the catalyst is carried out by applying an external magnet device. It is both “green” and efficient. The catalyst was fully characterized by spectroscopic, magnetic, adsorptive and thermal techniques (TEM, SEM, FTIR, TGA, XRD, BET, elemental analysis (CHNOS) and VSM). [ABSTRACT FROM AUTHOR]

Abstract: Treatment of aqueous formic acid (85%) with structurally diverse amines in the presence of a catalytic amount of sulfonic acid supported on hydroxyapatite-encapsulated-γ-Fe2O3 [HAp@-γ-Fe2O3] (0.9mol.%) as a heterogeneous, reusable and highly efficient catalyst gave the corresponding formamides in good to excellent yields at room temperature. The magnetically catalytic system was recovered by-passing time consuming filtration operation by using an external magnet device. In addition to facility, this methodology, it also enhances product purity and promises economic as well as environmental benefits. [Copyright &y& Elsevier]

A variety of monospiro-2-aminopyran derivatives such as (IV), (VII), and (X) (24 examples) are synthesized via three-component coupling of isatin (I) or ninhydrin (VIII) with malononitrile (II) and 1,3-dicarbonyl compounds. [ABSTRACT FROM AUTHOR]