Phase transformation in the "Brodie graphite oxide-acetonitrile" system - influence of the oxidizing level of the material

Reversible phase transformation in the Brodie graphite oxide-acetonitrile system, which is intercalation or release of part of the sorbed liquid from the interplanar space accompanied by an increase or a decrease in interplanar distances, is commonly observed in twice-oxidized materials. We observed this phenomenon for once-, twice- and thrice-oxidized materials using the EPR spin probe technique, DSC, and temperature programmed XRD. It was shown that all materials under study formed similar low temperature (LT) and high temperature (HT) swollen structures with acetonitrile. The phase transformation of these structures is observed for materials with different oxidation levels in the same temperature range (∼20 K). The twice- and thrice-oxidized Brodie graphite oxides form swollen structures with the same parameters, while the once-oxidized material sorbs less acetonitrile at lower temperatures, but shows the same interplanar distances as those in twice- and thrice-oxidized materials. The spin probe technique has proven its sensitivity to the appearance of small amounts of the new forming swollen structures, which makes this method useful in studies of phase transformations.

Thermal Conductivity of Detonation Nanodiamond Hydrogels and Hydrosols by Direct Heat Flux Measurements

The methodology and results of thermal conductivity measurements by the heat-flow technique for the detonation nanodiamond suspension gels, sols, and powders of several brands in the range of nanoparticle concentrations of 2-100% w/w are discussed. The conditions of assessing the thermal conductivity of the fluids and gels (a FOX 50 heat-flow meter) with the reproducibility (relative standard deviation) of 1% are proposed. The maximum increase of 13% was recorded for the nanodiamond gels (140 mg mL-1 or 4% v/v) of the RDDM brand, at 0.687 ± 0.005 W m-1 K-1. The thermal conductivity of the nanodiamond powders is estimated as 0.26 ± 0.03 and 0.35 ± 0.04 W m-1 K-1 for the RUDDM and RDDM brands, respectively. The thermal conductivity for the aqueous pastes containing 26% v/v RUDDM is 0.85 ± 0.04 W m-1 K-1. The dignities, shortcomings, and limitations of this approach are discussed and compared with the determining of the thermal conductivity with photothermal-lens spectrometry.

Green and rapid preparation of long-term stable aqueous dispersions of fullerenes and endohedral fullerenes: The pros and cons of an ultrasonic probe

A green, scalable, and sustainable approach to prepare aqueous fullerene dispersions (AFD) C60, C70, endohedral metallofullerene Gd@C82, and their derivatives C60Cl6, C70Cl10, and supramolecular and ester-like derivatives, 10 fullerene species total, is proposed. For the first time, an immersed ultrasonic probe was used to preparing dispersions for pristine fullerenes without addends. Both ultrasound-assisted solvent-exchange and direct sonication techniques for AFD preparation using an immersed probe were tested. The average time for AFD preparation decreases 10-15 times compared to an ultrasound-bath-assisted technique, while final fullerene concentrations in AFDs remained at tens of ppm (up to 80 ppm). The aqueous dispersions showed long-term stability, a negatively charged surface with a zeta potential up to -32 mV with an average nanocluster diameter of no more than 180 nm. The total anionic and cationic compositions of samples were found by inductively coupled plasma atomic emission spectroscopy and chromatographic techniques. The highlights and challenges of using an ultrasound probe for AFD production are discussed.

Mobility of liquids intercalated into the interplane space of graphite oxide as revealed by a combination of 19F NMR, 1H NMR and EPR spin probe methods

A combination of ¹⁹F and ¹H NMR with the Carr–Purcell–Meiboom–Gill (CPMG) pulse sequence was used to examine the mobility of liquids in the interplane space of graphite oxide (GO) for the first time.

Absorption spectra of nanodiamond aqueous dispersions by optical absorption and optoacoustic spectroscopies

The multispectral modality and technique for optically dense samples of optoacoustic spectroscopy were applied to measure spectra and high absorbances of concentrated aqueous dispersions of undoped nanodiamonds. The data from optoacoustic and optical transmission measurements and DSC data of the mean particle size by the Gibbs-Kelvin equation are compared to estimate the difference in composition of various nanodiamond trademarks. Optoacoustic spectra confirm the contribution of surface dimer chains into the absorption of nanodiamonds in the long wavelength range. Optoacoustic and conventional absorption spectra of aqueous solutions of nanodiamond fractions after centrifugation (15300g) and ultracentrifugation (130000g) revealed a separation of a highly absorbing non-diamond sp² phase. The two-step separation by ultracentrifugation followed by extra centrifugation made it possible to isolate a highly absorbing and soluble nanodiamond phase with the particle size of 3.6 nm, showing a change in spectra compared to the starting nanodiamond material.

Multilayered intercalation of 1-octanol into Brodie graphite oxide

Multilayered intercalation of 1-octanol into the structure of Brodie graphite oxide (B-GO) was studied as a function of temperature and pressure. Reversible phase transition with the addition/removal of one layer of 1-octanol was found at 265 K by means of X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC). The same transition was observed at ambient temperature upon a pressure increase above 0.6 GPa. This transition was interpreted as an incongruent melting of the low temperature/high pressure B-GO intercalated structure with five layers of 1-octanol parallel to GO sheets (L-solvate), resulting in the formation of a four-layered structure that is stable under ambient conditions (A-solvate). Vacuum heating allows the removal of 1-octanol from the A-solvate layer by layer, while distinct sets of (00l) reflections are observed for three-, two-, and one-layered solvate phases. Step by step removal of the 1-octanol layers results in changes of distance between graphene oxide planes by ∼4.5 Å. This experiment proved that both L- and A-solvates are structures with layers of 1-octanol parallel to GO planes. Unusual intercalation with up to five distinct layers of 1-octanol is remarkably different from the behaviour of small alcohol molecules (methanol and ethanol), which intercalate B-GO structure with only one layer under ambient conditions and a maximum of two layers at lower temperatures or higher pressures. The data presented in this study make it possible to rule out a change in the orientation of alcohol molecules from parallel to perpendicular to the GO planes, as suggested in the 1960s to explain larger expansion of the GO lattice due to swelling with larger alcohols.

[Disability as a medical and social indicator of health status and aging among Russian Population]

According to the State Statistics a comparative analysis of total disability in the Russian Federation in 2010-2016 years was conducted, taking into account the performance of the working-age and over working-age population. The necessity of integration policy towards the older generation and social policy in respect of disabled persons is shown: it is advisable to make adjustments to the national strategies and programs involving the duties of authorities to protect and promote the rights of disabled people, the development of preventive, rehabilitation, medical and social trends in the interests of senior citizens are involved.

[Socio-medical aspects of primary disability among those of working and over working age in Russian Federation]

According to the State Statistics a the indicators of primary disability in 2003-2015 years in Russia were studied, taking into account the population in working and over working age first time recognized as disabled persons. The necessity of medical organizations improvement during the medical and social expertise of patients in different ages was shown. The characteristics of social and medical features of the primary disability were presented that should be taken into consideration in the development of social protection programs, rehabilitation of disabled people and disability prevention, especially among elderly citizens.

[INVOLVEMENT OF 5-OPIOID RECEPTORS IN THE INCREASED RESISTANCE OF HEART AND MITOCHONDRIA TO IMPACT OF ISCHEMIA-REPERFUSION AFTER ADAPTATION TO CHRONIC CONTINUOUS HYPOXIA]

It was investigated the involvement of cardiac Ϭ-opioid receptors (OR) in increasing the resistance of the heart and myocardial mitochondria to ischemia-reperfusion after adaptation rats to chronic continuous normobaric hypoxia (CCNH). Rats were subjected to CCNH for 21 days at 12 % O2. It was evoked global ischemia (45 minutes) and reperfusion (30 minutes) of the isolated perfused heart. Adaptation to CCNH promoted a reduction of creatine kinase release from necrotic cardiomyocytes during reperfusion and improved reperfusion recovery of heart contractility. Mitochondrial respiratory and state of MPT pore were more resistant to ischemia-reperfusion in adapting rats. Perfusion of isolated hearts with TIPP(0) (30 nM/l, a selective Ϭ-OR-antagonist) or naltriben (1 nM/l, a selective 52-OR-antagonist) completely eliminated the cardioprotective effect of CCNH. BNTX (1 nM/l, a selective Ϭ-OR-antagonist) had no effect on the cardioprotective effect of CCNH. This data suggest that cardiac 52-OR involved in the increased resistance of the heart and mitochondria to ischemia-reperfusion after adaptation rats to CCNH.

Improving the dispersity of detonation nanodiamond: differential scanning calorimetry as a new method of controlling the aggregation state of nanodiamond powders

Detonation nanodiamond (ND) is a suitable source material to produce unique samples consisting of almost uniform diamond nanocrystals (d = 3-5 nm). Such samples exist in the form of long stable aqueous dispersions with narrow size distribution of diamond particles. The material is finding ever increasing application in biomedicine. The major problem in producing monodispersed diamond colloids lies in the necessity of deagglomeration of detonation soot and/or removing of clusters formed by already isolated core particles in dry powders. To do this one must have an effective method to monitor the aggregation state or dispersity of powders and gels prior to the preparation of aqueous dispersions. In the absence of dispersity control at various stages of preparation the reproducibility of properties of existing ND materials is poor. In this paper we introduce differential scanning calorimetry (DSC) as a new tool capable to distinguish the state of aggregation in dry and wetted ND materials and to follow changes in this state under different types of treatment. Samples with identical X-ray diffraction patterns (XRD) and high resolution transmission electron microscopy (HRTEM) images gave visibly different DSC traces. Strong correlation was found between dynamic light scattering (DLS) data for colloids and DSC parameters for gels and powders of the same material. Based on DSC data we improved dispersity of existing ND materials and isolated samples with the best possible DSC parameters. These were true monodispersed easily dispersible fractions of ND particles with diameters of ca. 3 nm.

[The International Classification of Functioning, Disability, and Health in the practice of a sociomedical examination service for internal diseases]

The paper gives the International Classification of Functioning, Disability, and Health (ICF), interactions between health changes, the personality and social factors of an individual with therapeutic diseases to define disability criteria and a scientific rationale for the necessity and scope of rehabilitative measures through public health and social protection organizations.

Structural features of molecular-colloidal solutions of C60 fullerenes in water by small-angle neutron scattering

Highly stable and reproducible molecular-colloidal water solutions of C60 fullerenes (FWS) obtained by transferring fullerenes from an organic solution into an aqueous phase with the help of ultrasonic treatment are investigated by means of small-angle neutron scattering (SANS). A polydispersity in the size of detected particles up to 84 nm is revealed. These particles are slightly anisotropic and have a characteristic size of approximately 70 nm. Along with it, there are some indications that a significant part of fullerenes composes particles with the size of the order of 1 nm. The contrast variation based on mixtures of light and heavy water shows that the mean scattering length density of the particles is close to that of the packed fullerene associates as well as that the characteristic size of possible fluctuations of the scattering length density within the particles does not exceed 2 nm. A smooth surface resulting in the Porod law for the scattering is detected. A number of models discussed in the literature are considered with respect to the SANS data.