Sorption of stable and radioactive Cs(I), Sr(II), Co(II) ions on Ti–Ca–Mg phosphates

Journal of Radioanalytical and Nuclear Chemistry - In this paper, we studied the features of stable and radioactive Cs(I), Sr(II) and Co(II) ions sorption on Ti–Ca–Mg phosphates. The...     

Two-step one-pot electrosynthesis and catalytic activity of xCoO–yCo(OH)2-supported silver nanoparticles

Journal of Solid State Electrochemistry - Efficient two-step electrosynthesis of xCoO–yCo(OH)2 (CoOxHy)-supported silver nanoparticles (AgNPs) is carried out in N,N-dimethylformamide (DMF)...     

Thermal transport of oil and polymer composites filled with carbon nanotubes

We studied the thermal transport properties of multi-walled carbon nanotubes (MWNTs) in polymer and oil matrices. The thermal conductivity of the oils and polymers increased linearly when adding tubes. We observe a particularly high increase in the thermal diffusivity of carbon-nanotube-loaded liquid crystal polymers (6×10⁻⁵ cm²/s wt%), which is due to a spontaneous alignment of the MWNTs. Carbon nanotubes increased the thermal conductivity of oil by a factor of three for 20 wt% loading. We found little or no dependence of the thermal enhancement on the specific flavor of multiwall nanotubes used in the composites. Carbon nanotubes are excellent nanoscale fillers for composites in thermal management application.     

Interpolymer complexes of copolymers of vinyl ether of diethylene glycol with poly(acrylic acid)

 The complex formation reactions of poly(vinyl ether of diethylene glycol) as well as vinyl ether of diethylene glycol–vinyl butyl ether copolymers with poly(acrylic acid) have been studied in aqueous and alcohol solutions. The formation of interpolymer complexes which were stabilized by hydrogen bonds was shown. The effects of molecular weight of poly(acrylic acid) and the nature of the nonionic polymer on the composition and stability of interpolymer complexes were clarified. The critical pH values of complexation were determined for different systems with various molecular weights and hydrophobic–hydrophilic balances. The stability of the interpolymer complexes formed in aqueous and alcohol solutions with respect to dimethylformamide addition was evaluated. The role of hydrophobic interactions and the presence of active groups on stability of the interpolymer complexes is discussed. Received: 23 July 2001 Accepted: 27 September 2001     

Tandem radical and non-radical reactions mediated with thiols--a new method of cleavage of allylic amines

Thiyl radical promotes the isomerisation of allylic amines into enamines via two consecutive hydrogen atom abstraction steps, and the subsequent polar addition of the corresponding thiol to the enamine results in the cleavage of the C-N bond via a thioaminal intermediate: this reaction provides a mild, metal-free methodology for the deprotection of allylated primary and secondary amines.     

High-temperature 2D Fermi surface of SrTiO3 studied by energy-filtered PEEM

Functional oxides displaying phenomena such as 2D electron gas (2DEG) at oxide interfaces represent potential technological breakthroughs for post-CMOS (Complementary Metal Oxide Semiconductor) electronics. Noninvasive techniques are required to study the surface chemistry and electronic structure underlying their often unique electrical properties. The sensitivity of photoemission electron microscopy (PEEM) to local potential, chemistry, and electronic structure makes it an invaluable tool for probing the near surface region of microscopic regions and domains of functional materials. In particular, PEEM allows single shot acquisition of the 2D Fermi surface and full angular probing of the symmetry-induced intensity modulations. We present results demonstrating a 2DEG at the surface of SrTiO₃(001) at 140 K. The 2DEG is created by soft X-ray irradiation and can be reversibly controlled by a combination of soft X-rays and oxygen partial pressure.     

Structural study and thermal behavior of novel interaction product of 4-amino-5-(furan-2-yl)-4H-1,2,4-triazole-3-thione with molecular iodine

Abstract

As a part of investigation of thyreostatic activity of mercapto-substituted triazoles, the structure, spectroscopic properties of 4-amino-5-(furan-2-yl)-4H-1,2,4-triazole-3-thione were obtained. 4-amino-5-(furan-2-yl)-4H-1,2,4-triazole-3-thione forms steady charge-transfer complex in dilute chloroform solution, coordinating one iodine molecule (lgβ?=?3.47). The reaction product of 4-amino-5-(furan-2-yl)-4H-1,2,4-triazole-3-thione is presented by uncharged adduct: C₆H₆N₄OS·I₂. The crystal structure of the adduct was studied in detail by single crystal X-ray diffraction. The results of thermogravimetric analysis revealed the stability of adduct in a solid state at the temperature range 50–500?°C.     

Advances in mucoadhesion and mucoadhesive polymers

Mucoadhesion is the ability of materials to adhere to mucosal membranes in the human body and provide a temporary retention. This property has been widely used to develop polymeric dosage forms for buccal, oral, nasal, ocular and vaginal drug delivery. Excellent mucoadhesive properties are typical for hydrophilic polymers possessing charged groups and/or non-ionic functional groups capable of forming hydrogen bonds with mucosal surfaces. This feature article considers recent advances in the study of mucoadhesion and mucoadhesive polymers. It provides an overview on the structure of mucosal membranes, properties of mucus gels and the nature of mucoadhesion. It describes the most common methods to evaluate mucoadhesive properties of various dosage forms and discusses the main classes of mucoadhesives.     

Collapse of Poly(methacrylic acid) Hydrogels in Response to Simultaneous Stimulation by an Electric Field and Complex Formation

Complex formation of poly(methacrylic acid) hydrogels with linear poly(ethylene glycol) has been studied at different pH values and in the presence of an electric field. The fastest contraction of the gel samples was observed under simultaneous action of electric field and complex formation.

Dependence of the volume ratio V/V₀ of PMAA sample on time: Sample in the absence of an electric field immersed in 0.1 M PEG solution at (1) pH 8.2, (2) at pH 5.1, and in the presence of an electric field (3) in water and (4) 0.1 M PEG solution at pH 5.1.     

Molecular structure of N-chlorosuccinimide studied by gas-phase electron diffraction and quantum-chemical methods

The molecular structure of N-chlorosuccinimide has been studied by GED method at the nozzle temperature of 116 °C. Vibrational corrections to the r _a parameters, Δ(r _a − r _e), have been calculated using the scaled quadratic and cubic force constants from B3LYP/6-31G(df,p) calculations. The force field scaling has been carried out using the IR and Raman spectra of the solid N-chlorosuccinimide. The molecular skeleton and the bond conformation around nitrogen were found to be planar within large experimental errors. The equilibrium geometrical parameters derived from the experimental data assuming C _2v molecular symmetry and those from MP2(fc)/6-311G(3df,2pd) calculations are in a good agreement.