Crystal structure and magnetization of a Co3B2O6 single crystal

The crystal structure and magnetic properties of Co₃B₂O₆ single crystals are studied. Orthorhombic symmetry with space group Pnnm is detected at room temperature. The measurements of static magnetization and dynamic magnetic susceptibility reveal two magnetic anomalies at T ₁ = 33 K and T ₂ = 10 K and an easy-axis magnetic anisotropy. The effective magnetic moment indicates a high-spin state of the Co²⁺ ion. A spin-flop transition is found at low temperatures and H _sf = 23 kOe. EXAFS spectra of the K-edge absorption of Co are recorded at various temperatures, the temperature-induced changes in the parameters of the local environment of cobalt are analyzed, and the effective Co-Co and Co-O distances are determined. The magnetic interactions in the crystal are analyzed in terms of an indirect coupling model.     

Ultrafast core-hole-induced dynamics in water probed by x-ray emission spectroscopy

The isotope effect and excitation-energy dependence have been measured in the oxygen K-edge x-ray emission spectrum (XES). The use of XES to monitor core decay processes provides information about molecular dynamics (MD) on an ultrafast time scale through the O1s lifetime of a few femtoseconds. Different nuclear masses give rise to differences in the dynamics and the observed isotope effect in XES is direct evidence of the importance of such processes. MD simulations show that even the excitation-energy dependence in the XES is mainly related to differences in core-excited-state dynamics.     

Laser-electron x-ray generator

The possibility of developing a laser-electron x-ray generator based on the Thomson scattering of laser radiation by relativistic electrons and prospects for its application are considered. In its specifications (brightness, average intensity, and dimensions), as well as its construction and operation cost, such a generator is intermediate between x-ray tubes and synchrotron sources. The configuration of channels and experimental stations intended for applications of an x-ray laser-electron generator in studies of the elemental composition and structure of materials is discussed.     

Study of the physicochemical properties and film structure of ternary graft copolymers of aromatic polyimide, ɛ-caprolactam,and ω-dodecanelactam

The microstructure of films of ternary graft copolymers of aromatic polyimide, ?-caprolactam, and ω-dodecanelactam has been studied by atomic force microscopy. It is shown that an increase in the content of ω-dodecanelactam units in copolymers leads to an increase in the diameter of spherulites composed of fibrils. Simultaneously, water absorption decreases and the mechanical properties and crystallinity of copolymer films change.     

Revealing the Influence of Silver in Ni–Ag Catalysts on the Selectivity of Higher Olefin Synthesis from Stearic Acid

Results on the conversion of stearic acid to olefins over Ni–Ag/γ-Al₂O₃ catalysts are presented. XANES and EXAFS experiments in situ and DFT calculations were applied to reveal the structure of active sites therein. It is shown that the introduction of Ag to Ni catalysts leads to an increase in the olefin yield. After a reduction in hydrogen (350°C, 3 h) alumina-supported nanoparticles of nickel sulfides and metallic Ag are formed. The role of metal hydrides formed during the reaction is extensively discussed.     

Proton conductivity of poly(arylene ether ketones) with different sulfonation degrees: Improvement via incorporation of nanodisperse zirconium acid phosphate

The proton conductivity of films based on sulfonated poly(arylene ether ketone) derived from bisphenol A and 4,4′-difluorobenzophenone of various modification degrees has been studied. The conductivity achieves high levels upon incorporation of a large amount of sulfo groups into the polymer. The conductivity of the samples with low sulfonation degrees may be increased via introduction of the nanodisperse zirconium acid sulfate additive.     

X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure study of water adsorption on pyridine-terminated thiolate self-assembled monolayers

Adsorption of water on self-assembled monolayers (SAMs) of 4-(4-mercaptophenyl)pyridine on gold at low temperatures under ultrahigh vacuum conditions is studied by synchrotron radiation X-ray photoelectron and absorption spectroscopy. Water adsorption induces a strong modification of the chemical state of the pyridine N atoms at the SAM/ice interface, indicative for strong H bonding and partial proton transfer between water molecules and pyridine moieties. Additionally, the initial molecular orientation within the SAM is changed upon formation of an adsorbed water multilayer.     

Binuclear metallochelates of 2-(N-tosylamino)benzal-2’-(hydroxymethyl)aniline: Syntheses,structures, and magnetic properties

Binuclear complexes of Co(II), Сu(II), and Pd(II) with 2-(N-tosylamino)benzal-2’-(hydroxymethyl)aniline are synthesized. The compositions and structures of the ligand and complexes are determined from the data of elemental analysis, IR spectroscopy, ¹Н, ¹³С, and ¹⁵N NMR spectroscopy, X-ray absorption spectroscopy, and magnetochemical measurements in a temperature range of 294–77.4 K. All complexes are dimeric. The Cu…Cu and Cо…Cо distances equal to 3.03 and 2.99 Å, respectively, are obtained for the Cu(II) and Co(II) complexes. These complexes are characterized by the antiferromagnetic exchange interaction with 2J = –630 and –42 cm^–1, respectively.     

Is X-ray absorption spectroscopy sensitive to the amino acid composition of functional proteins?

We report, compare, and analyze near-edge X-ray absorption fine structure (NEXAFS) spectra of powder samples of four different functional proteins, namely, lysozyme, ovalbumin, bovine serum albumin, and type-I collagen, at all relevant absorption edges. The spectra of all of the above proteins were found to be quite similar and to exhibit minor differences only. Nevertheless, despite the general similarity, the spectra of the individual proteins are distinguishable, and some of the respective differences clearly correlate with their amino acid compositions. Further factors affecting the NEXAFS spectra of proteins beyond the building block approach are discussed.     

Unsymmetrical Trifluoromethyl Methoxyphenyl β-Diketones: Effect of the Position of Methoxy Group and Coordination at Cu(II) on Biological Activity

Copper(II) complexes with 1,1,1-trifluoro-4-(4-methoxyphenyl)butan-2,4-dione (HL1) were synthesized and characterized by elemental analysis, FT-IR spectroscopy, and single crystal X-ray diffraction. The biological properties of HL1 and cis-[Cu(L1)₂(DMSO)] (3) were examined against Gram-positive and Gram-negative bacteria and opportunistic unicellular fungi. The cytotoxicity was estimated towards the HeLa and Vero cell lines. Complex 3 demonstrated antibacterial activity towards S. aureus comparable to that of streptomycin, lower antifungal activity than the ligand HL1 and moderate cytotoxicity. The bioactivity was compared with the activity of compounds of similar structures. The effect of changing the position of the methoxy group at the aromatic ring in the ligand moiety of the complexes on their antimicrobial and cytotoxic activity was explored. We propose that complex 3 has lower bioavailability and reduced bioactivity than expected due to strong intermolecular contacts. In addition, molecular docking studies provided theoretical information on the interactions of tested compounds with ribonucleotide reductase subunit R2, as well as the chaperones Hsp70 and Hsp90, which are important biomolecular targets for antitumor and antimicrobial drug search and design. The obtained results revealed that the complexes displayed enhanced affinity over organic ligands. Taken together, the copper(II) complexes with the trifluoromethyl methoxyphenyl-substituted β-diketones could be considered as promising anticancer agents with antibacterial properties.