New oxygen-and lead-deficient lead borate Pb 0.9 (I) Pb 0.6 (II) [BO2.25]2 = 2Pb0.75[BO2.25] and its relation to aragonite and calcite structures

Anhydrous oxygen-and lead-deficient lead borate of the composition Pb _0.9 ^(I) Pb _0.6 ^(II) [BO_2.25]₂ = 2Pb_0.75[BO_2.25] (sp. gr. P312) has been obtained by the hydrothermal synthesis. New acentric borate possesses optical nonlinearity comparable with the optical nonlinearity of α-quartz. The crystal structure of new borate is determined and refined by two X-ray diffraction methods—the single crystal diffractometry and the full-profile analysis. All the positions in the structure, except for those of the boron atom in the triangular coordination, are occupied only partly; one of the two lead positions is split. It is established that new borate is closely related to calcium carbonates—aragonite, calcite, and paralstonite. With an increase of the temperature, new borate undergoes the reversible phase transition into the centrosymmetric, most probably, aragonite-like phase.     

Improvement of the Antimicrobial Activity of Oregano Oil by Encapsulation in Chitosan—Alginate Nanoparticles

Oregano oil (OrO) possesses well-pronounced antimicrobial properties but its application is limited due to low water solubility and possible instability. The aim of this study was to evaluate the possibility to incorporate OrO in an aqueous dispersion of chitosan—alginate nanoparticles and how this will affect its antimicrobial activity. The encapsulation of OrO was performed by emulsification and consequent electrostatic gelation of both polysaccharides. OrO-loaded nanoparticles (OrO-NP) have small size (320 nm) and negative charge (−25 mV). The data from FTIR spectroscopy and XRD analyses reveal successful encapsulation of the oil into the nanoparticles. The results of thermogravimetry suggest improved thermal stability of the encapsulated oil. The minimal inhibitory concentrations of OrO-NP determined on a panel of Gram-positive and Gram-negative pathogens (ISO 20776-1:2006) are 4–32-fold lower than those of OrO. OrO-NP inhibit the respiratory activity of the bacteria (MTT assay) to a lower extent than OrO; however, the minimal bactericidal concentrations still remain significantly lower. OrO-NP exhibit significantly lower in vitro cytotoxicity than pure OrO on the HaCaT cell line as determined by ISO 10993-5:2009. The irritation test (ISO 10993-10) shows no signs of irritation or edema on the application site. In conclusion, the nanodelivery system of oregano oil possesses strong antimicrobial activity and is promising for development of food additives.     

Synthesis and Crystal Structure of New Iodate Na3Fe[IO3]6 of the A3M[IO3]6 Structural Family (A = Na,K, Rb,Cs, Tl; M = Ti,Fe, Ge,In, Pt)

Crystallography Reports - Crystals of new iodate Na3Fe[IO3]6 were prepared by the hydrothermal synthesis (the unit cell parameters a = 6.6886(2) Å, b = 6.7756(3) Å, c = 10.1396(6) Å,...     

Impedance Study of GaN and InGaN Semiconductor Anion Selective Electrodes

The response of potentiometric anion selective electrodes employing undoped GaN or In_0.2Ga_0.8N films as sensing element to detect various anions was investigated in solutions of KF, KNO₃, KCl, HOC₆H₄COONa, KSCN, CH₃COOK, KClO₄ and KBr salts. The calibration plots for the GaN and In_0.2Ga_0.8N semiconductor electrodes contained linear regions extending over four decades of activity change in most solutions. The structure of the GaN and In_0.2Ga_0.8N semiconductor electrode/ electrolyte interface was studied through electrochemical impedance spectroscopy. Analogous equivalent circuits modeling the GaN or In_0.2Ga_0.8N electrode/electrolyte interface were proposed and their parameters were calculated. The space charge layer of the GaN and In_0.2Ga_0.8N semiconductors dominated the impedance of the electrochemical system at high frequencies (>10 kHz), whereas at low frequencies (<10 kHz), the impedance was controlled by the diffusion of electroactive species across the layer of adsorbed ions at the surface of the electrode. Results imply a strong dependence of the electrodes performance on the adsorption capacity of tested anions.     

Conversions of Coumarins Accompanied by Intermediate Opening and Recyclization of the Lactone Ring. 2. Study of the Interaction of Malonic Acid Hydrazide and Amide Derivatives with 3-Acyl(3-cyano, 3-ethoxycarbonyl)Coumarins

Reaction between the N,N′-diisopropylidene and N,N′-diacetyl derivatives of malonic acid dihydrazide and 3-acyl(3-cyano, 3-ethoxycarbonyl)coumarins under the conditions of the Michael reaction lead to the formation of N′-isopropylidene and N′-acetyl derivatives of coumarin-3-carboxylic acid hydrazide. Ethoxycarbonylacethydrazide reacts in an analogous manner. Special features have been studied of the interaction of malonic acid amide derivatives with unsubstituted coumarin and with coumarins containing electron-withdrawing groupings in position 3 of the ring. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1502–1514, October, 2005.     

Integrity of endothelium in cryopreserved human cornea

The aim of the present study was to elaborate an optimal method for cryopreservation of human donor cornea for transplantation and to follow the morphological changes in the structure of the endothelial cell layer using scanning electron microscopy (SEM). Sixteen groups, with four donor cornea each, were cryopreserved at cooling rates of 1 degree C per min and 5 degree C per min. Four cryoprotectants (glycerol, dimethyl sulfoxide, 1,2-propanediol, polyethylene glycol-400) in two concentrations (5% and 10% v/v) were prepared on the bases of medium Optisol GS supplied with 20% v/v human serum albumin. Four additional human cornea were used as controls. Endothelial cell recovery of the cornea after thawing and 24 hours culture, was calculated as a percent of the preserved recovered cells. Sufficient recovery of the endothelial cell layer, making the cornea suitable for transplantation was obtained using the cryoprotectants dimethyl sulfoxide and especially polyethylene glycol-400.     

New chelating sorbents based on pyrazolone containing amines immobilized on styrene-divinylbenzene copolymer-I Synthesis and analytical characterization

A series of new cheating sorbents has been prepared by modification of styrene-divinylbenzene copolymer with different pyrazolone-containing amines. The substances were characterized by elemental analysis and infared spectroscopy. The complexation ability of the sorbents towards alkali, alkaline-earth, transition and precious metals has been studied. The new sorbents may successfully be applied to the simultaneous preconcentration of alkaline-earth and transition elements in neutral medium and to the selective separation of precious metals in acidic medium.     

New boron-oxygen layer in the structure of barium hydrodecaborate Ba5[B20O33(OH)4] ⋅ H2O

The crystal structure of the new synthetic compound Ba₅[B₂₀O₃₃(OH)₄] ? H₂O was established by the methods of X-ray diffraction (a Stoe IPDS diffractometer, λMoK _α?, 1860 independent reflections, anisotropic refinement, R = 1.95%, localization of hydrogen atoms): a = 9.495(2) Å, b = 6.713(1) Å, c = 11.709(2) Å, β = 95.09(1)°, sp. gr. P2, Z = 1. The structure is based on double pseudohexagonal layers consisting of BO₄-tetrahedra and BO₃ triangles linked into three-membered rings in two mutually perpendicular directions. The double layers adjacent along the [100] direction are linked together through the Ba-polyhedra and hydrogen bonds with the participation of the OH-groups occupying the “end” vertices of two B-triangles. The interlayer space is also filled with a sheet of Ba-polyhedra. The structure of the compound is compared to the structures of topologically similar Ba and Ca borates and hydroborates.     

New triclinic modification of lead iodate Pb(IO3)2: Synthesis and crystal structure

A new triclinic modification of lead iodate Pb(IO₃)₂ (space group $C\bar 1$ ) is obtained under hydrothermal conditions. The crystal structure is determined without preliminary knowledge of the chemical formula. [IO₃]^? groups, which are characteristic of pentavalent iodine, have a typical umbrella-like configuration. The new phase has a more complex structure than the known orthorhombic modification. The arrangement of heavy Pb and I atoms follows a’ = a/3 pseudoperiodicity. In the layers of two types that form sheets parallel to the ab plane, Pb and I atoms have different coordinations. A polytypic nature of the new modification is responsible for the one-dimensional disordering along the a axis as well as different variants of layer alternation. It is possible to obtain crystals of acentric and polar derivatives of the centrosymmetric phase that will be promising for application.     

K8Gd3Si12O32Cl · 2H2O,a new member of the family of porous silicates with K and RE elements

Crystals of K₈Gd₃Si₁₂O₃₂Cl · 2H₂O (space group $P\bar 1$ ), a new member of the family of porous silicates containing rare earths, are obtained under hydrothermal conditions. The structure retains the main features of the family in which original one-story layers of Si-tetrahedra formed by 6-membered rings of two types and large-in-diameter 8-membered and 12-membered rings are bound by Gd-octahedra to form a framework. Large pores in the interlayer space of the mixed framework are filled with K⁺ ions. The penetration of Cl^? ions from a concentrated mineralizing solution into the centers of the eight-membered rings of the layer corroborates the ion-exchanging properties of the crystals of this structural type. The filling of rings and pores of different types in different members of the family by K⁺ and Cl^? ions, hydroxyl groups, and water molecules is analyzed.