Effect of thermal annealing on ZnO:Al thin films grown by spray pyrolysis

We report the effect of thermal annealing in air on the structural and optical properties of undoped and aluminium-doped (1%–4%) zinc oxide (AZO) thin films, grown by the spray pyrolysis technique on quartz substrates. Films were characterized by X-ray diffraction, low-temperature photoluminescence, electrical resistivity, and Raman spectroscopy after annealing at temperatures between 500 and 900 C. Annealing in air improves the long-range order crystalline quality of the bulk crystals, but promotes a number of point defects in the surface affecting both the resistivity and the photoluminescence.     

The interaction of the antitoxin DM43 with a snake venom metalloproteinase analyzed by mass spectrometry and surface plasmon resonance

DM43 is a circulating dimeric antitoxin isolated from Didelphis aurita, a South American marsupial naturally immune to snake envenomation. This endogenous inhibitor binds non‐covalently to jararhagin, the main hemorrhagic metalloproteinase from Bothrops jararaca snake venom, and efficiently neutralizes its toxicity. The aim of this study was to apply mass spectrometry (MS) and surface plasmon resonance (SPR) to improve the molecular characterization of this heterocomplex. The stoichiometry of the interaction was confirmed by nanoelectrospray ionization‐quadrupole‐time‐of‐flight MS; from native solution conditions, the complex showed a molecular mass of ~94 kDa, indicating that one molecule of jararhagin (50 kDa) interacts with one monomer of DM43 (43 kDa). Although readily observed in solution, the dimeric structure of the inhibitor was barely preserved in the gas phase. This result suggests that, in contrast to the toxin–antitoxin complex, hydrophobic interactions are the primary driving force for the inhibitor dimerization. For the real‐time interaction analysis, the toxin was captured on a sensor chip derivatized with the anti‐jararhagin monoclonal antibody MAJar 2. The sensorgrams obtained after successive injections of DM43 in a concentration series were globally fitted to a simple bimolecular interaction, yielding the following kinetic rates for the DM43/jararhagin interaction: k_a = 3.54 ± 0.03 × 10⁴ M^?1 s^?1 and k_d = 1.16 ± 0.07 × 10^?5 s^?1, resulting in an equilibrium dissociation constant (K_D) of 0.33 ± 0.06 nM. Taken together, MS and SPR results show that DM43 binds to its target toxin with high affinity and constitute the first accurate quantitative study on the extent of the interaction between a natural inhibitor and a metalloproteinase toxin, with unequivocal implications for the use of this kind of molecule as template for the rational development of novel antivenom therapies. Copyright © 2012 John Wiley & Sons, Ltd.     

Inclusion relations for the spaces L(ℝ), \mathcal{H}\mathcal{K} (ℝ) ∩ \mathcal{B}\mathcal{V} (ℝ), and L 2(ℝ)

The inclusion relations for the spaces $ \mathcal{H}\mathcal{K} $ (I), L(I), $ \mathcal{H}\mathcal{K} $ (I) ∩ $ \mathcal{B}\mathcal{V} $ (I), and L ²(I) are found. On unbounded intervals, functions in $ \mathcal{H}\mathcal{K} $ (I) ∩ $ \mathcal{B}\mathcal{V} $ (I) need not be Lebesgue integrable.     

New compounds from hyptis. X-ray crystal and molecular structures of olguine

The structure (including absolute stereochemistry) of olguine, an unsaturated lactone isolated from an unclassified $\text{Hyptis}$ species, has been established by spectroscopic and X-ray analysis.     

Diterpenes from teucrium capitatum L. X-ray crystal and molecular structure of lolin

Lolin, a new diterpene of the $\text{ent}$-clerodane type has been isolated from Teucrium capitatum. The X-ray structure and spectroscopic data of lolin is given.     

Molecular structure ofrac-(4R*,4aS*,10aS*)-4-nitro-1,2,3,4,4a,9,10,10a-octahydrophenanthren-4a-ol,an unusual by-product of nitration of a crude 9,10-dihydrophenanthrene

A new nitro-octahydrophenanthrenol has been isolated by nitration of a crude 9,10-dihydrophenanthrene, which was identified by nmr and X-ray diffraction analysis. Crystallographic and molecular structure confirmed the compound as therac-(4R^*,4aS^*,10aS^*)-4-Nitro-1,2,3,4,4a,9,10,10a-octahydrophenanthren-4a-ol. The crystal was triclinic, ,a=10.549(3),b=8.530(3),c=7.131(1)Å, =107.07(3), =91.62(3), =96.27(4)°. Cyclohexane and cyclohexene rings aretrans-fused and have chair and half-chair conformations, respectively. The molecules are associated by hydrogen bridge between the hydroxyl oxygen and both nitro oxygens.     

Molecular and crystal structure of 1,4-diacethoxy naphthalene: Structural analysis of methyl substituted 1,4-diacethoxynaphthalenes

Methyl substituted 1,4-diacethoxynaphthalenes have been synthetized and analyzed by means of ultraviolet and¹H-nmr. Positional effects of the methyl substitution on the spectroscopic parameters have been rationalized. 6,7-Dimethyl-1,4-diacethoxynaphthalene,V, has been analyzed by X-ray diffraction techniques. Crystals are monoclinic P2₁,a=8.816(1),b=26.676(7),c=6.189(1) Å,=103.9 (2) ° and four molecules in the unit cell.     

Synthesis of Non-Aqueous Neptunium(III) Halide Solvates from NpO2

Two Np(III) halides, NpI₃(THF)₄ and NpBr₃(THF)₄, have been prepared and isolated in high yields as described in this work. Starting with neptunia (NpO₂), NpCl₄(DME)₂ was first generated in an updated, higher yielding synthesis than what was previously reported by using HCl/HF. This material was then reduced with KC₈, followed by subsequent ligand exchange, to generate NpBr₃(THF)₄ and NpI₃-(THF)₄. Full characterization by single-crystal X-ray crystallography, ¹H NMR spectroscopy and electronic absorption spectroscopy confirmed the molecular formulas and oxidation states. These trivalent materials are straightforward to synthesize and can be used as starting materials for non-aqueous Np(III) chemistry, obviating the need for rare and restricted Np metal and elemental halogens.     

Computational study of ligand binding in lipid transfer proteins: Structures,interfaces, and free energies of protein‐lipid complexes

Plant nonspecific lipid transfer proteins (nsLTPs) bind a wide variety of lipids, which allows them to perform disparate functions. Recent reports on their multifunctionality in plant growth processes have posed new questions on the versatile binding abilities of these proteins. The lack of binding specificity has been customarily explained in qualitative terms on the basis of a supposed structural flexibility and nonspecificity of hydrophobic protein‐ligand interactions. We present here a computational study of protein‐ligand complexes formed between five nsLTPs and seven lipids bound in two different ways in every receptor protein. After optimizing geometries in molecular dynamics calculations, we computed Poisson‐Boltzmann electrostatic potentials, solvation energies, properties of the protein‐ligand interfaces, and estimates of binding free energies of the resulting complexes. Our results provide the first quantitative information on the ligand abilities of nsLTPs, shed new light into protein‐lipid interactions, and reveal new features which supplement commonly held assumptions on their lack of binding specificity. © 2012 Wiley Periodicals, Inc.