Deep neural network analysis of nanoparticle ordering to identify defects in layered carbon materials

Smoothness/defectiveness of the carbon material surface is a key issue for many applications, spanning from electronics to reinforced materials, adsorbents and catalysis. Several surface defects cannot be observed with conventional analytic techniques, thus requiring the development of a new imaging approach. Here, we evaluate a convenient method for mapping such “hidden” defects on the surface of carbon materials using 1–5 nm metal nanoparticles as markers. A direct relationship between the presence of defects and the ordering of nanoparticles was studied experimentally and modeled using quantum chemistry calculations and Monte Carlo simulations. An automated pipeline for analyzing microscopic images is described: the degree of smoothness of experimental images was determined by a classification neural network, and then the images were searched for specific types of defects using a segmentation neural network. An informative set of features was generated from both networks: high-dimensional embeddings of image patches and statics of defect distribution.

Defectiveness of carbon material surface is a key issue for many applications. Pd-nanoparticle SEM imaging was used to highlight “hidden” defects and analyzed by neural networks to solve order/disorder classification and defect segmentation tasks.     

Structural characteristics of chlorine-substituted diazadienes in the solid state from35NQR data

The quadrupole resonance spectra and the quadrupole spin-lattice relaxation times of the³⁵Cl nuclei are correlated with the molecular structures of the two chlorine-containing diazadienes CCl₃CCl=NCCl=NC₆H₅ and CCl₃CCl=NCCl=NCCl₂CCl₃. The monotropic polymorphism found in the case of the second crystal is discussed.Perm State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 2, pp. 84–87, March–April, 1993.     

Preparative fractionation of cerebral gangliosides with the aid of ion-exchange chromatography on Spheron CH 300

A new preparative method is proposed for the separation of natural mixtures of gangliosides into fractions of mono-, di-, and trisialogangliosides which is based on ion-exchange chromatography on a weak anion-exchange resin — Spheron CH 300. The latter ensures a considerably faster separation than the ion-exchange resins usually employed.Scientific-Research Laboratory of Biologically Active Substances of Hydrobionts, USSR Ministry of Health, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 28–30, January–February, 1990.     

Simulation of the radiation-chemical transformations of acetic acid in aqueous solutions

A general model for the radiolysis of acetic acid and its aqueous solutions is proposed. The model adequately describes experimental data on the degradation of the acid and the formation of gases (H₂, CO₂, and CH₄) in aqueous solutions at various pH values.     

Apparent two-dimensional behavior of TiO2 nanotubes revealed by light absorption and luminescence

Optical absorption and photoluminescence (PL) properties of colloidal TiO(2) nanotubes, produced by the alkali hydrothermal method, were studied at room temperature in the range 300-700 nm. Nanotubes having an internal diameter in the range 2.5-5 nm have very similar optical properties, in contrast to the expected behavior for quasi-1-D systems. This is explained by the complete thermal smearing of all 1-D effects, due to the large effective mass of charge carriers in TiO(2), resulting in an apparent 2-D behavior of TiO(2) nanotubes.     

Effect of the carbon atom coordination on the thermoactivated motion of the carbon-bonded trichloromethyl group

The reorientational motion of the trichloromethyl group depending on the environment of the carbon atom is considered based on the chlorine-35 nuclear quadrupole resonance (NQR) data. The study is performed for CCl₃ groups bonded to tri- and tetracoordinated carbon atoms in the crystalline compounds CCl₃CCl=NR (R = CH₂C₆H₅ and CCl₃CCl₃) and CCl₃CXClN=CClC₆H₄NO_2-n (X = H and Cl).₃₅Cl NQR studies of thermoactivated motion in 70 solid trichloromethyl-containing compounds are summarized. The ranges of activation energies of CCl₃ reorientations at tri- and tetracoordinated carbon atoms were determined to be 10-50 and 30-90 kJ/mole, respectively, the activation energy being markedly greater in the latter case. CCl₃ reorientations may be completely frozen by the bulky substituents which may be present along with CCl₃ in the tetracoordinated carbon bonds. Translated fromZhurnal Strukturnoi Khimii, Vol. 41, No. 4, pp. 737-746, July-August, 2000     

Electrical and magnetic properties of nanodiamond and pyrocarbon composites

The electrical and magnetic properties of the nanodiamond composites comprising nanodiamond, pyrolytic carbon, and nanosized pores were studied. The composites are p-type semiconductors and their resistance decreases by 12 orders of magnitude as the pyrocarbon-to-diamond ratio γ increases from 0 to 80 wt %. Evidence for paramagnetic properties of the nanodiamond composites was obtained. The observed properties are explained by increased concentration of surface Tamm states. The paramagnetic properties are explained in terms of the electron spins localized on the nanodiamond surface in the composite.     

Study of magnetic properties of Pd<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Fe<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>)<Subscript>0.95</Subscript>Mn<Subscript>0.05</Subscript> alloy using polarized muons and neutrons

The Pd_1?x Fe _x )_0.95Mn_0.05 alloy with random competing interaction was studied by measuring the muon spin relaxation in an external transverse magnetic field and in a zero magnetic field. Using the measured temperature dependence of the dynamic relaxation rate λ and the characteristics of the distribution of local static fields, the phase states of the sample under study are refined. In particular, it is shown that the ferromagnetic and spin-glass states coexist simultaneously in the sample below 25 K. Combined studies of the sample using the μSR and neutron depolarization methods made it possible to determine the size of magnetic inhomogeneities to be 2–6 μm in the temperature range 5–40 K.