Phase transitions and electrical properties of CsH(SO4)0.76(SeO4)0.24 mixed crystals

The study by X-ray diffraction, calorimetry, vibrational and impedance spectroscopy of CsH(SO₄)_0.76(SeO₄)_0.24 new solid solution is presented. Crystals of this composition undergo two phase transitions at T = 333 and 408 K. The last one at 408 K is a superionic-protonic transition (SPT) related to a rapid [HS(Se)O₄⁻] reorientation and fast H⁺ diffusion. A sudden jump in the conductivity plot confirms the presence of this transition. Above 408 K, this high temperature phase is characterized by high electrical conductivity (7 × 10^t-3 Ω⁻ cm⁻¹) and low activation energy (E_a < 0.3 eV).     

EPR study of the two-dimensional molecular composite [NH3-(CH2)5-NH3]CuCl4: Evidence for both spin diffusion and spin anisotropies

The quasi two-dimensional single crystal [NH₃-(CH₂)₅-NH₃]CuCl₄ has been studied by EPR measurements at X-band, room temperature andT = 100 K in three perpendicular planes (a, b), (a, c), (b, c*). This compound crystallizes in the monoclinic system with four entities per unit cell. Only one EPR exchange-collapsed line was observed for the four magnetically inequivalent copper ions in the lattice at room temperature. A careful analysis of experimental data permits us to obtain the principal values of theg-factor:g _┴=2.052 andg _║=2.267. The EPR linewidth exhibits a minimum along the г п ≈/4 direction of (a, c*) plane attributable to spin diffusion. Along the г п ≈/4 direction of (b, c*) plane the linewidth exhibits a maximum attributable to the two magnetically inequivalent sub-systems located in two adjacent mineral sheets. The simulations of EPR spectra obtained along the bisector of (b, c*) angle at room temperature and atT = 100 K show that exchange interaction between these two dissimilar sub-systems is nearly equal to zero.     

New Bacteriocin from Bacillus clausii StrainGM17: Purification, Characterization, and Biological Activity

A bacteriocin-producing strain (9,000 AU/ml) was isolated from the rhizosphere of Algerian healthy plants Ononis angustissima Lam. and identified as Bacillus clausii strain GM17. The bacteriocin, called Bac-GM17, was purified from the culture supernatant after heat treatment, ammonium sulfate precipitation, Sephadex G-50 chromatography and Mono Q fast-performance liquid chromatography (FPLC). Based on matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis, the purified Bac-GM17 is a monomer protein with a molecular mass of 5,158.11 Da. The N-terminal sequencing allowed for the straightforward identification of its first 20 residues, which were of pure bacteriocin. It also revealed that this bacteriocin contained a unique sequence, namely DWTCSKWSCLVCDDCSVELT, which suggests the identification of a novel compound. Bac-GM17 was extremely heat stable (20 min at 120 °C) and was stable within the pH range (3–9). It was found to be resistant to the proteolytic action of trypsin, pepsin, papain, pronase E, and proteinase K. It was also noted to display a bactericidal mode of action against Agrobacterium tumefaciens C58 and a fungistatic mode of action against Candida tropicalis R2 CIP203.     

Synthesis of new annulated pyridazine derivatives and studying their antioxidant and antimicrobial activities

Benzil was reacted with cyanoacetohydrazide under microwave irradiation to give 3-oxo-5,6-diphenyl-2,3-dihydropyridazine-4-carbonitrile 1 which used as starting material for the synthesis of new heterocyclic compounds. Chlorination of pyridazinone 1 with POCl₃ afforded the chloro-pyridazine derivative 3, which then condensed with 2-aminothiazole or hydrazine hydrate to produce 3,4-diphenyl-5H-thiazolo[3′,2′:1,2]pyrimido[4,5-c]pyridazin-5-one 5 or 3-hydrazinyl-5,6-diphenylpyridazine-4-carbonitrile 6, respectively. New Schiff bases were obtained by condensation reactions of compound 6 with different aldehydes. On the other hand, compound 6 reacted with different carbon electrophiles naming acetyl acetone, diethyl malonate, and phenyl isothiocyanate producing new pyarazolo-pyridazine derivatives 11, 12, and 14, respectively. Chemical structures of all newly synthesized compounds were confirmed on the basis of spectral data and had been screened for antimicrobial and antioxidant activity.     

The Bieberbach conjecture for restricted initial coefficients

Mathematische Zeitschrift -     

Crystal structure of bis 4-benzyl piperidinium monohydrogenmonophosphate pentahydrate, [C6H5CH2CHCH2CH2NH2CH2CH2]2HPO4·5H2O

The salt bis 4-benzyl piperidinium monohydrogenmonophosphate pentahydrate is orthorhombic with the following unit cell dimensions: a = 11.235(2) Å, b = 27.924(6) Å, c = 9.321(4) Å space group Pca2₁ with Z = 4. The structure was solved by the Patterson method and refined to final R value of 0.049 for 1802 independent reflections. The flack parameter is 0.14 with an e.s.d. of 0.23. The structure consists of infinite parallel two-dimensional [110] planes built of mutually connected ions and water molecules by strong O—H,...,O and N—H,...,O hydrogen bonding. There are no contacts other than normal van der Waals interactions between the layers.     

Direct synthesis of nanowires with anatase and TiO2-B structures at near ambient conditions

In this study, we present a new approach toward titanium oxide nanowires. In this approach, the growth formation of the wires sets in at a temperature as low as 40 degrees C under ambient pressure. Moreover, we provide evidence that nanowires with distinctive TiO2-anatase and TiO2-B structures can be directly produced without further thermal treatment using controlled reaction conditions.     

New insight in the structure–luminescence relationships of Ca9Eu(PO4)7

The double phosphate Ca₉Eu(PO₄)₇, obtained by solid state reaction, was found to be isotypic with Ca₃(PO₄)₂, with space group R3c and unit cell parameters a=10.4546(1) Å, c=37.4050(3) Å, V=3540.67(9) Å³, Z=6. The structure parameters refined using the Rietveld method showed that europium shares positions M1, M2 and M3 with calcium, contradicting previously published Mössbauer results. Low temperature luminescence under selective excitation of Eu³⁺ in Ca₉Y_1−xEu_x(PO₄)₇ and in Ca₉Eu(PO₄)₇ samples was studied, confirming the Eu³⁺ distribution into these sites. At 10 K, ⁵D₀→⁷F₀ emission lines of Eu³⁺ were observed at 578.5, 579.5, 580.1 nm for the M3, M1 and M2 sites, respectively. High temperature X-ray powder diffraction evidenced a second-order phase transition around 573 °C.