The magnetic, resonance, and electric properties of ${\text{La}}_x{\text{MnO}}_{3+\delta }$ $\left(0.815\le x\le 1.0\right)$ polycrystalline samples have been studied in the temperature range of 77–370 K and at high pressures of up to 11.5 kbar. It is shown that the increase in the La/Mn ratio gives rise to a change in the low temperature magnetic state from ferromagnetic to cluster spin glass, as well as to a drastic transformation of electric properties. A peculiar double-peaked shape is characteristic of the resistivity versus temperature curves for the intermediate range of $x$ values. Within this range, the application of high pressures drastically changes both the value of resistivity and the character of its temperature dependence. It is shown that the approach, which regards the state of ${\text{La}}_x{\text{MnO}}_{3+\delta }$ polycrystals as a mixture of interpenetrating paramagnetic insulating and ferromagnetic metallic phases, is able to successfully describe the peculiarities of the temperature dependence of total resistivity, as well as the features of its transformation under hydrostatic compression. It is demonstrated that the formation of a low temperature resistance peak is a result of a wide-temperature-region coexistence of the phases, which exhibits opposite trends in the temperature dependences of resistivity. The conclusion is made that not only does hydrostatic compression result in drastic changes in the relative volume fractions of the coexisting phases, but it also affects the intrinsic parameters of each of the phases.

Targeting experimental orthotopic glioblastoma with chitosan-based superparamagnetic iron oxide nanoparticles (CS-DX-SPIONs) Maxim Shevtsov,1–4 Boris Nikolaev,5 Yaroslav Marchenko,5 Ludmila Yakovleva,5 Nikita Skvortsov,5 Anton Mazur,6 Peter Tolstoy,6 Vyacheslav Ryzhov,7 Gabriele Multhoff2 1Department of Cell Biotechnology, Institute of Cytology of the Russian Academy of Sciences, St Petersburg, Russia; 2Department of Radiation Immuno Oncology, Technische Universität München, Klinikum rechts der Isar, Munich, Germany; 3Department of Biotechnology, Pavlov First Saint Petersburg State Medical University, St Petersburg, Russia; 4Department of Pediatric Neurosurgery, Polenov Russian Scientific Research Institute of Neurosurgery, St Petersburg, Russia; 5Department of Nanomedicine, Research Institute of Highly Pure Biopreparations, St Petersburg, Russia; 6Department of NMR, Saint Petersburg State University, St Petersburg, Russia; 7Department of NMR, NRC “Kurchatov Institute”, Petersburg Nuclear Physics Institute, Gatchina, Russia Background: Glioblastoma is the most devastating primary brain tumor of the central nervous system in adults. Magnetic nanocarriers may help not only for a targeted delivery of chemotherapeutic agents into the tumor site but also provide contrast enhancing properties for diagnostics using magnetic resonance imaging (MRI).Methods: Synthesized hybrid chitosan-dextran superparamagnetic nanoparticles (CS-DX-SPIONs) were characterized using transmission electron microscopy (TEM) and relaxometry studies. Nonlinear magnetic response measurements were employed for confirming the superparamagnetic state of particles. Following in vitro analysis of nanoparticles cellular uptake tumor targeting was assessed in the model of the orthotopic glioma in rodents.Results: CS-DX-SPIONs nanoparticles showed a uniform diameter of 55 nm under TEM and superparamagentic characteristics as determined by T1 (spin-lattice relaxation time) and T2 (spin-spin relaxation time) proton relaxation times. Application of the chitosan increased the charge from +8.9 to +19.3 mV of the dextran-based SPIONs. The nonlinear magnetic response at second harmonic of CS-DX-SPIONs following the slow change of stationary magnetic fields with very low hysteresis evidenced superparamagnetic state of particles at ambient temperatures. Confocal microscopy and flow cytometry studies showed an enhanced internalization of the chitosan-based nanoparticles in U87, C6 glioma and HeLa cells as compared to dextran-coated particles. Cytotoxicity assay demonstrated acceptable toxicity profile of the synthesized nanoparticles up to a concentration of 10 µg/ml. Intravenously administered CS-DX-SPIONs in orthotopic C6 gliomas in rats accumulated in the tumor site as shown by high-resolution MRI (11.0 T). Retention of nanoparticles resulted in a significant contrast enhancement of the tumor image that was accompanied with a dramatic drop in T2 values (P<0.001). Subsequent histological studies proved the accumulation of the nanoparticles inside glioblastoma cells.Conclusion: Hybrid chitosan-dextran magnetic particles demonstrated high MR contrast enhancing properties for the delineation of the brain tumor. Due to a significant retention of the particles in the tumor an application of the CS-DX-SPIONs could not only improve the tumor imaging but also could allow a targeted delivery of chemotherapeutic agents. Keywords: brain tumor, glioblastoma, tumor targeting, chitosan, superparamagnetic iron oxide nanoparticles, magnetic resonance imaging

A brief overview is given of the papers published over the last two decades on the subject of solid-state ¹³C NMR spectra of such carbon nanostructures as milled graphite and its oxide, graphene, graphene oxide, carbon nanotubes, nanodiamonds, fullerenes and their derivatives. The main focus is put on the characteristic values of experimental isotropic ¹³C NMR chemical shifts and their interpretation in terms of local chemical environments of carbon nuclei.

Novel mixed matrix dense and supported membranes based on biopolymer sodium alginate (SA) modified by fullerenol were developed. Two kinds of SA–fullerenol membranes were investigated: untreated and cross-linked by immersing the dry membranes in 1.25 wt % calcium chloride (CaCl₂) in water for 10 min. The structural and physicochemical characteristics features of the SA–fullerenol composite were investigated by Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopic methods, scanning electron (SEM) and atomic force (AFM) microscopies, thermogravimetric analysis (TGA), and swelling experiments. Transport properties were evaluated in pervaporation dehydration of isopropanol in a wide concentration range. It was found that the developed supported cross-linked SA-5/PAN^CaCl2 membrane (modified by 5 wt % fullerenol) possessed the best transport properties (the highest permeation fluxes 0.64–2.9 kg/(m² h) and separation factors 26–73,326) for the pervaporation separation of the water–isopropanol mixture in the wide concentration range (12–90 wt % water) at 22 °C and is suitable for the promising application in industry.

The structure, the structure imperfection, and the magnetoresistance, magnetotransport, and microstructure properties of rare-earth perovskite La_0.3Ln_0.3Sr_0.3Mn_1.1O_3–δ manganites are studied by X-ray diffraction, thermogravimetry, electrical resistivity measurement, magnetic, ⁵⁵Mn NMR, magnetoresistance measurement, and scanning electron microscopy. It is found that the structure imperfection increases, and the symmetry of a rhombohedrally distorted R3̅c perovskite structure changes into its pseudocubic type during isovalent substitution for Ln = La³⁺, Pr³⁺, Nd³⁺, Sm³⁺, or Eu³⁺ when the ionic radius of an A cation decreases. Defect molar formulas are determined for a real perovskite structure, which contains anion and cation vacancies. The decrease in the temperatures of the metal–semiconductor (T_ms) and ferromagnet–paramagnet (T_C) phase transitions and the increase in electrical resistivity ρ and activation energy E_a with increasing serial number of Ln are caused by an increase in the concentration of vacancy point defects, which weaken the double exchange 3d⁴(Mn³⁺)–2p⁶(O^2–)–3d³(Mn⁴⁺)–V^(a)–3d⁴(Mn³⁺). The crystal structure of the compositions with Ln = La contains nanostructured planar clusters, which induce an anomalous magnetic hysteresis at T = 77 K. Broad and asymmetric ⁵⁵Mn NMR spectra support the high-frequency electronic double exchange Mn³⁺(3d⁴) ↔ O^2–(2p⁶) ↔ Mn⁴⁺(3d³) and indicate a heterogeneous surrounding of manganese by other ions and vacancies. A correlation is revealed between the tunneling magnetoresistance effect and the crystallite size. A composition–structure imperfection–property experimental phase diagram is plotted. This diagram supports the conclusion about a strong influence of structure imperfection on the formation of the magnetic, magnetotransport, and magnetoresistance properties of rare-earth perovskite manganites.

Tris(2-pyridyl)phosphine oxide reacts with CuSCN to form a variety of luminescent complexes, depending on the specified metal-to-ligand ratio and the solvent used, viz. mononuclear [Cu(N,N′,N′′-Py₃PO)(NCS)], dinuclear (N,N′-Py₃PO)Cu(^SCN _NCS)Cu[(N,N′-Py₃PO)], their co-crystal (2 : 1, correspondingly) and trinuclear {Cu(NCS)[SCNCu(N,N′,N′′-Py₃PO)]₂}. In the solid state, these complexes feature red-orange emission upon UV photoexcitation. The reaction of tris(2-pyridyl)phosphine with CuSCN quantitatively produces an almost insoluble coordination polymer, [Cu(Py₃P)NCS]_n, which exhibits bright green emission. The synthesized compounds are the first members of the hitherto unknown family of Cu(I) thiocyanate complexes supported by tripodal ligands.