Properties of Methacrylic Acid–Methyl Acrylate Copolymers of Varied Structure

Physicomechanical and surface properties of films of copolymers of methacrylic acid with methyl acrylate, which have close compositions and molecular masses (M_n ≈ 5.7 × 10⁴) and various chain structures (gradient copolymer and statistical copolymer), were studied. The thermodynamic characteristics of the copolymers were determined; two glass-transition points (29.6 and 141.0°C) were found for the gradient copolymer, and one glass-transition point of 40.1°C, for the copolymer with a statistical distribution of units along the chain. It was found that more mechanically strong films with tensile stress of 2.8 MPa are characteristic of the gradient copolymer. The wetting method was used to determine by using the Hood–Kaelble–Dann–Fowkes approach the surface Gibbs energies of the films and their polar and dispersion components. Atomic-force microscopy was used to find heterogeneities (0.1–0.3 μm) on the surface of a film of a statistical copolymer, whereas the film of a gradient polymer has a homogeneous structure.     

Rheological properties of poly(ethylene glycol) solutions and gels

By the interaction of a water–glycol solution of poly(ethylene glycol) (PEG) with calcium chloride dihydrate, a gel was produced. It was determined that, below a certain shear rate, this gel is a Newtonian fluid; however, above a certain shear rate, which depends on the gel viscosity, the properties of this gel are anomalous: the gel flow instantaneously completely stops. The viscosity of the gels was found to exponentially increase with increasing concentration of the cross-linking metal at constant PEG concentration. The density of the gels linearly increases with increasing concentration of the cross-linking metal at constant PEG concentration.     

Blistering of mechanically polished molybdenum upon its exposure to deuterium-containing plasma

Recent data on the blistering process in polished polycrystalline Mo for the case of direct-current glow discharge in deuterium and D₂/2–4 mol % O₂ or N₂ admixtures, at an energy of incident molecular ions of 70–120 eV and a pressure of 14 Pa, are reported. Depending on the method of metal surface polishing, the initial metal grains are broken up into mutually disordered regions of smaller sizes (subgrains); the chemical composition of the damaged layer changes. In the formed structure, blistering can develop easily or be impeded. Small additions of O₂ or N₂ to deuterium facilitate the blistering.     

Thermodynamic properties of a second-generation poly(phenylene-pyridyl) dendron with a dodecyl-decorated periphery

The heat capacity of a partially crystalline second-generation poly(phenylene-pyridyl) dendron with a dodecyl-decorated periphery is studied by high-precision adiabatic vacuum and differential scanning calorimetry in the temperature range of 6 to 530 K. The thermodynamic characteristics of the glass’s transition and melting are determined from the calorimetric data and the degree of its crystallinity is estimated (α = 30%). Standard thermodynamic functions (C_p°, H°-H°(0), S°-S°(0), and G°-H°(0)) for a partially crystalline dendron in the range of T → 0 to 480 K are calculated.     

The thermodynamic properties of <Emphasis Type="Italic">bis</Emphasis>-(η<Superscript>5</Superscript>-cyclopentadienylirondicarbonyl)

The temperature dependence of the heat capacity of crystalline bis-(η⁵-cyclopentadienylirondicarbonyl) was studied over the temperature range 5–495 K in precision adiabatic vacuum and differential scanning calorimeters. The temperature dependence contained an anomaly (160–295 K) with a maximum at 250 K interpreted as a λ transition in the solid state. The fusion of the sample occurred at 435–491 K; it was accompanied by partial substance decomposition. The thermodynamic functions of crystalline bis-(η⁵-cyclopentadienylirondicarbonyl) were calculated from T→0 to 472.9 K. The enthalpy of combustion of the compound was determined in an isothermal calorimeter with a stationary bomb. The standard thermodynamic functions of its formation in the crystalline state at 298.15 K were calculated.     

Thermodynamic properties of graphite-like nanostructures prepared by thermobaric treatment of fullerite C60

Temperature dependences of the heat capacities of disordered graphite-like nanostructures prepared by the thermobaric treatment of fullerite C₆₀ (p = 2 and 8 GPa, T = 1373 K) were measured in the temperature ranges from 7 to 360 K in an adiabatic vacuum calorimeter and from 330 to 650 K in a differential scanning calorimeter. At T < 50 K, the dependences obtained were analyzed using the Debye theory of the heat capacity of solids and its multifractal version. The fractal dimensions D were determined and some conclusions on the heterodynamic character of the structures studied were made. The thermodynamic functions C _p ^o T), H ^o(T) − H ^o(0), S ^o(T) − S ^o(0), and G ^o(T) − H ^o(0) were calculated in the temperature range from T → 0 to 610 (650) K. The thermodynamic properties of the graphite-like nanostructures studied and some carbon allotropes were compared. The standard entropies of formation Δ_f S ^o of the graphite nanostructures studied and diamond were calculated along with the standard entropies of the reactions of their synthesis from the face-centered cubic phase of fullerite C₆₀ and their interconversions at T = 298.15 K. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1940–1945, September, 2008.     

Sc3+ Chloro and Alkyl Complexes Coordinated by Pincer NHC-Tethered Bis(phenolate) Ligands

Bis(phenolate) ligands with benzimidazole-2-ylidene ( L¹) and tetrahydropyrimidine-2-ylidene ( L² ) linkers proved to be suitable coordination environments for the synthesis of isolable Sc³⁺ chloro and alkyl complexes. The treatment of Sc(CH₂SiMe₃)₃(THF)₂ with equimolar amounts of [ L^1,2H₃ ] Cl afforded chloro complexes L^1,2ScCl ( solv ) ₂ (solv=THF, Py) in 76–85 % yields. L^1,2ScCl ( THF ) ₂ were also prepared by the salt metathesis reactions of ScCl₃ with [ L^1,2 ] Na₂ generated from [ L^1,2H₃ ] Cl and 3 equiv. of NaN(SiMe₃)₂ (−40 °C, THF) and isolated in somewhat lower yields (68–73 %). L²ScCl ( THF ) ₂ was subjected to the alkylation reaction with LiCH₂SiMe₃ affording alkyl derivative [ L²Sc ( CH₂SiMe₃ )] ₂ . This compound can be alternatively prepared by the subsequent reactions of [ L²H₃ ] Cl with equimolar amount of NaN(SiMe₃)₂ and Sc(CH₂SiMe₃)₃(THF)₂. In the dimeric alkyl compound [ L²Sc ( CH₂SiMe₃ )] ₂ , one of the phenoxide groups of the dianionic ligand is coordinated to one scandium center, while the second one features μ-bridging coordination with two metal centers.     

Formation of Films of Tungsten and its Oxides in a High-Frequency Capacitive Discharge in a D<Subscript>2</Subscript>-O<Subscript>2</Subscript> Mixture

A technique for tungsten-film deposition on different substrates in asymmetrical high-frequency (1.76 MHz) capacitive discharge in a D₂?6.5 mol % O₂ mixture under a total pressure of 15 Pa and at 60–130°C is considered. A circular W strip near the upper inner edge of a cylindrical hollow cathode with a radius of 4.2 cm and a height of 10 cm is the source of W particles. The smooth transition from sputtering of the inner surface to deposition occurs at a distance of about 4 cm from the upper boundary of the open part of the cathode. W, Mo, ZrO₂, Si, and Cu substrates are placed in the lower closed end (bottom) and on the inner lateral cathode surface. At the upper cathode edge the sputtering yield is (4–5) × 10^?2 at/ion. The mass rate of W deposition on the cathode bottom does not depend on the substrate type and is 40 μg/(cm² h). The peculiarities of the composition, morphology, and structure of W films obtained on the lateral surface and bottom of the hollow cathode are discussed.     

Atheroprotective Effects of Glycyrrhiza glabra L.

Cardiovascular diseases associated with atherosclerosis are the major cause of death in developed countries. Early prevention and treatment of atherosclerosis are considered to be an important aspect of the therapy of cardiovascular disease. Preparations based on natural products affect the main pathogenetic steps of atherogenesis, and so represent a perspective for the long-term prevention of atherosclerosis development. Numerous experimental and clinical studies have demonstrated the multiple beneficial effects of licorice and its bioactive compounds—anti-inflammatory, anti-cytokine, antioxidant, anti-atherogenic, and anti-platelet action—which allow us to consider licorice as a promising atheroprotective agent. In this review, we summarized the current knowledge on the licorice anti-atherosclerotic mechanisms of action based on the results of experimental studies, including the results of the in vitro study demonstrating licorice effect on the ability of blood serum to reduce intracellular cholesterol accumulation in cultured macrophages, and presented the results of clinical studies confirming the ameliorating activity of licorice in regard to traditional cardiovascular risk factors as well as the direct anti-atherosclerotic effect of licorice.     

Structural Study of Polymorphism in [La(Gly)3·2H2O](ClO4)3

Journal of Chemical Crystallography - The crystal structures of [La(Gly)3·2H2O](ClO4)3 were determined by X-ray diffraction analysis at temperatures 100&nbsp;K and 300&nbsp;K: space...