Preconcentration, determination and speciation of iron by solid-phase extraction using dimethyl (E)-2-[(Z)-1-acetyl)-2-hydroxy-1-propenyl]-2-butenedioate

A new sensitive and selective procedure for speciation of trace dissolved Fe(III) and Fe(II), using modified octadecyl silica membrane disks and determination by flame atomic absorption spectrometry was developed. A ML3 complex is formed between the ligand and Fe(III) responsible for extraction of metal ion on the disk. Various factors influencing the separation of iron were investigated and the optimized operation conditions were established. Under optimum conditions, an enrichment factor of 166 was obtained for Fe3+ ions. The calibration graph using the preconcentration system for Fe3+ was linear between 40.0 and 1000.0 μg L-1.

Ni(II), Cu(II), AND Zn(II) COMPLEXES DERIVED FROM A NEW SCHIFF BASE 2-((Z)-(3-METHYLPYRIDIN-2- YLEIMINO)METHYL)PHENOL AND SYNTHESIS OF NANO SIZED METAL OXIDE PARTICLES FROM THESE COMPOUNDS

Synthesis, spectral identification, and magnetic properties of three complexes of Ni(II), Cu(II), and Zn(II) are described. All three compounds have the general formula [M(L)2(H2O)2], where L = deprotonated phenol in the Schiff base 2-((z)-(3-methylpyridin-2-yleimino)methyl)phenol. The three complexes were synthesized in a one-step synthesis and characterized by elemental analysis, Fourier transform infrared spectroscopy, electronic spectra, X-ray diffraction (XRD), and room temperature magnetic moments. The Cu(II) and Ni(II) complexes exhibited room temperature magnetic moments of 1.85 B.M. per copper atom and 2.96 B.M. per nickel atom. The X-band electron spin resonance spectra of a Cu(II) sample in dimethylformamide frozen at 77 K (liquid nitrogen temperature) showed a typical ΔMS = ± 1 transition. The complexes ([M(L)2(H2O)2]) were investigated by the cyclic voltammetry technique, which provided information regarding the electrochemical mechanism of redox behavior of the compounds. Thermal decomposition of the complexes at 750 ºC resulted in the formation of metal oxide nanoparticles. XRD analyses indicated that the nanoparticles had a high degree of crystallinity. The average sizes of the nanoparticles were found to be approximately 54.3, 30.1, and 44.4 nm for NiO, CuO, and ZnO, respectively.

Paleogenetic and taphonomic analysis of human bones from Moa, Beirada, and Zé Espinho Sambaquis, Rio de Janeiro, Brazil

The present paper discusses mtDNA and taphonomy of human remains from Moa, Beirada, and Zé Espinho sambaquis of Saquarema, state of Rio de Janeiro, Brazil. New human bone dating by 14C-AMS for Moa archeological site (3810+50 BP - GX-31826-AMS) is included. Preservation of microscopic lamellae and DNA is not related to the macroscopic integrity of the bones. Results here suggest that the preservation of amplifiable DNA fragments may have relation to the preservation of the lamellar arrangement as indicated by optical microscopic examination (polarized light). In 13 human bone fragments from Moa, Beirada, and Zé Espinho it was possible to sequence mtDNA from the 3 individuals of Moa, and from 1 of 4 individuals of Beirada, whose bones also show extensive areas with preserved lamellar structures. The 6 human bone fragments of Zé Espinho and 3 of the 4 fragments of Beirada showed extensive destruction of cortical microstructure represented by cavities, intrusive minerals, and agglomerated microscopic bodies of fungi and bacteria; it was not possible to extract mtDNA from these samples. The results support the hypothesis that the preservation of the microscopic osteon organization is a good predictor for DNA preservation. It was also confirmed the C haplogroup antiquity in Brazil.

Mutants of common bean alpha-amylase inhibitor-2 as an approach to investigate binding specificity to alpha-amylases

Despite the presence of a family of defense proteins, Phaseolus vulgaris can be attacked by bruchid insects resulting in serious damage to stored grains. The two distinct active forms of a-amylase inhibitors, a-AI1 and a-AI2, in P. vulgaris show different specificity toward a-amylases. Zabrotes subfasciatus a-amylase is inhibited by a-AI2 but not by a-AI1. In contrast, porcine a-amylase is inhibited by a-AI1 but not by a-AI2. The objective of this work was to understand the molecular basis of the specificity of two inhibitors in P. vulgaris (a-AI1 and a-AI2) in relation to a-amylases. Mutants of a-AI2 were made and expressed in tobacco plants. The results showed that all the a-AI2 mutant inhibitors lost their activity against the insect a-amylases but none exhibited activity toward the mammalian a-amylase. The replacement of His33 of a-AI2 with the a-AI1-like sequence Ser-Tyr-Asn abolished inhibition of Z. subfasciatus a-amylase. From structural modeling, the conclusion is that the size and complexity of the amylase-inhibitor interface explain why mutation of the N-terminal loop and resultant abolition of Z. subfasciatus a-amylase inhibition are not accompanied by gain of inhibitory activity against porcine a-amylase.

Estructura cristalina del N-isopropil-2-ciano-3(5'-nitrofuril)acrilamida

C11H11N3O4 , Mr = 249.23, triclinic, , a = 5.453(1), b = 22.873(5), c = 4.893(1) Å, a = 94.47(3), b = 96.36(3), g = 86.27(3)º, V = 603.7(8)ų,Z = 2, Dx = 1.371 Mg/m-3,l(Cu Ka1) = 1.54178Å, m = 0.86mm-1, room temperature. The crystal structure of N-isopropyl-2-cyano-3(5'-nitrofuryl) - acrylamide has been determined by Direct Methods and refined to R = 0.086 for 797 observed reflections. The molecules in the crystal are packed at normal van der Waals forces and by an hydrogen bond between N1-H1...02i (N1...02i: 2.910(1)Å), with i=x,y,z+1).

Síntese e caracterização de cloro[ácido 2-(difenilfosfino)benzóico]-ouro(I) e alguns de seus derivados

In this contribution a few new gold(I)phosphine complexes, [2-(PPh2)C6H4CO 2H]AuX (where X = Cl, SCN, Br3) and a similar gold(III) derivative [{2-(PPh2)C6H4CO 2H}AuIII Cl (C6H4CH2NMe2 )]Cl have been synthesised and characterised. The phosphine, 2-(diphenylphosphino)benzoic acid, has been employed for the first time in gold chemistry. This ligand is potentially bidentate through bonding of the phosphine and carboxylate groups. The X-ray structure of the complex chloro[2-(diphenylphosphino) benzoic acid]gold(I) has been elucidated and the bond lengths encountered show great similarity to those of chloro(triphenylphosphine)gold(I). [2-(PPh2)C6H4CO 2H]AuCl crystallises in the space group P2(1)/c with a = 9.113(2) Å, b = 10.925(2) Å, c = 23.069(4) Å, beta = 99.95º(3), V = 2299 ų, Z = 4 and R = 0.091. Biological tests for anti-fungal and anti-bacterial activity demostrate that [2-(PPh2)C6H4CO 2H]AuCl exhibits broad spectrum activity against a range of organisms.

Recomendações para calibração em Química Analítica parte 2: calibração multianalito

This paper is a translation of an IUPAC document by K. Danzer, M. Otto and L. A. Currie (Pure Appl. Chem., 2004, 76(6), 1215-1225). Its goal is to establish a uniform and meaningful standard for terminology (in Portuguese), notation, and formulation concerning multispecies calibration in analytical chemistry. Calibration in analytical chemistry refers to the relation between sample domain and measurement domain (signal domain) expressed by an analytical function x = f s (Q) representing a pattern of chemical species Q and their amounts or concentrations x in a given test sample and a measured function y = f (z) that may be a spectrum, chromatogram, etc. Simultaneous multispecies analyses are carried out mainly by spectroscopic and chromatographic methods in a more or less selective way. For the determination of n species Qi (i=1,2, ..., n), at least n signals must be measured which should be well separated in the ideal case. In analytical practice, the situation can be different.

A Theoretical investigation of a potential high energy density compound 3,6,7,8-tetranitro-3,6,7,8-tetraaza-tricyclo[3.1.1.1(2,4)]octane

The B3LYP/6-31G (d) density functional theory (DFT) method was used to study molecular geometry, electronic structure, infrared spectrum (IR) and thermodynamic properties. Heat of formation (HOF) and calculated density were estimated to evaluate detonation properties using Kamlet-Jacobs equations. Thermal stability of 3,6,7,8-tetranitro-3,6,7,8-tetraaza-tricyclo [3.1.1.1(2,4)]octane (TTTO) was investigated by calculating bond dissociation energy (BDE) at the unrestricted B3LYP/6-31G(d) level. Results showed the N-NO2 bond is a trigger bond during the thermolysis initiation process. The crystal structure obtained by molecular mechanics (MM) methods belongs to P2(1)/C space group, with cell parameters a = 8.239 Å, b = 8.079 Å, c = 16.860 Å, Z = 4 and r = 1.922 g cm-3. Both detonation velocity of 9.79 km s-1 and detonation pressure of 44.22 GPa performed similarly to CL-20. According to the quantitative standards of energetics and stability, TTTO essentially satisfies this requirement as a high energy density compound (HEDC).

Influência da taxa de dose na degradação do herbicida ácido diclorofenóxiacético (2,4-d) por meio da radiação gama do cobalto-60

Métodos convencionais de descontaminação ambiental, algumas vezes apenas transferem esses resíduos de um lugar para outro. Esse estudo tem como objetivo checar a influência de diferentes taxas de doses de radiação gama do cobalto-60 na degradação do herbicida 2,4-D, em água e metanol. Os resultados mostraram que o 2,4-D, em água, foi totalmente degradado em uma dose de 30 kGy, utilizando-se taxa de dose de 2,7 kGy h-1 e 20 kGy com uma taxa de dose de 5- 60 kGy h-1. Para o metanol, a total degradação do 2,4-D ocorreu com uma dose de 150 kGy e taxa de dose de 2,7 kGy h-1 e 100 kGy utilizando-se taxa de dose de 5- 60 kGy h-1. Assim conclui-se que a degradação do herbicida 2,4-D é dependente da dose e da taxa de dose de radiação.O valor radiolítico da degradação do 2,4-D foi calculado.

La marchitez tardía del maíz (Zea mays L.) causada por Cephalosporium maydis en la Península Ibérica, y otros hongos asociados

Las especies de hongos de suelo asociadas a Cephalosporium maydis como agente causal de la marchitez tardía del maíz en la Península Ibérica se identificaron muestreando 19 campos con síntomas de marchitez en las principales zonas de cultivo entre 2011 y 2012. En el 47% de los campos no se identificó C. maydis, pero sí Fusarium graminearum, F. verticillioides, F. equiseti, F. proliferatum, Macrophomina phaseolina, Rhizoctonia solani y Trichoderma harzianum infectando las plantas de maíz. En los campos restantes, junto a C. maydis se identificaron otros hongos de suelo en porcentajes apreciables: F. verticillioides (19%), F. proliferatum (19%), F.equiseti (9%), F. oxysporum (9%) y Pythium oligandrum (9%). El crecimiento vascular de C. maydis y de otras especies fúngicas en plantas de maíz se confirmó analizando plantas con marchitez procedentes de tres campos diferentes. Tanto C. maydis como F. graminearum, F. equiseti, F. proliferatum y T. harzianum se aislaron de la inserción entre la raíz y tallo y a 10 cm de altura en el tallo de las plantas. El efecto de la infección por C. maydis sobre la producción de las plantas de maíz se cuantificó en macetas y condiciones seminaturales en el 2011. En plantas inoculadas se obtuvo una reducción del peso de las mazorcas del 54%, además de pesos de raíz y de parte aérea (tallo y hojas) significativamente menores en comparación con el control no inoculado, lo que sugiere el gran impacto económico que puede tener la marchitez tardía en condiciones naturales. Asimismo este trabajo pone de manifiesto el grado de complejidad de la etiología de la marchitez tardía, que debería ser estudiado mediante la confirmación de la patogenicidad de los hongos de suelo identificados en maíz, con el fin de determinar el papel que puede jugar cada una de estas especies en el desarrollo de la enfermedad y/o severidad de los síntomas.

Efeito de subdoses de 2,4-D na produtividade do algodão e suscetibilidade da cultura em função de seu estádio de desenvolvimento

O objetivo deste trabalho foi avaliar o efeito de subdoses de 2,4-D no desenvolvimento e produtividade da cultura do algodoeiro. Dois experimentos foram conduzidos utilizando-se da variedade IAPAR-95 e o sistema de avaliação por meio de testemunhas duplas. No primeiro experimento, as aplicações foram realizadas no estádio F1 (início do florescimento), aplicando-se dosagens de 0,84; 1,68; 3,36; 6,72; 13,44 e 26,88 g de equivalente ácido (e.a.) por hectare, equivalentes a derivas de 0,125; 0,25; 0,5; 1,0; 2,0 e 4,0% da dose de 670 g e.a. ha-1. No segundo experimento, os tratamentos foram constituídos pela combinação em esquema fatorial de duas doses (6,72 e 13,44 g e.a. ha-1) e três épocas de aplicação (C1, C3/C4 e C6), visando a avaliar a variação da sensibilidade do algodão ao 2,4-D em função de seu estádio de desenvolvimento. Os resultados evidenciaram que doses maiores que 3,36 g e.a. ha-1 (0,50%) aplicadas na fase de florescimento afetaram de forma significativa a produtividade, que a queda dos botões florais foi o sintoma mais importante para a redução da produtividade. No segundo experimento, observou-se que a sensibilidade do algodão caiu drasticamente em função do estádio de desenvolvimento. O único tratamento que provocou queda significativa de produtividade foi a dose de 13,44 g e.a. ha-1 (2,0%) aplicada no estádio C1. Dessa forma, a partir do momento em que as maçãs começam a se formar, a sensibilidade da cultura cai substancialmente.

Efeito de subdoses de 2,4-D na produtividade de fumo e suscetibilidade da cultura em função de seu estádio de desenvolvimento

O presente trabalho teve como objetivo determinar os efeitos de subdoses do herbicida 2,4-D na cultura do fumo. Os experimentos foram conduzidos a campo durante o ano de 2003, no município de Santa Isabel do Ivaí - PR, utilizando-se de fumo tipo Virgínia. No primeiro experimento, foram aplicadas, no estádio de pré-florescimento, doses de 0,84; 1,68; 3,36; 6,72; 13,44 e 26,88 g e.a. ha-1 de 2,4-D, equivalentes à deriva de 0,125; 0,25; 0,5; 1,0; 2,0 e 4,0% de produtos comerciais aplicados a 1,0 L ha-1 (670 g e.a. ha-1). Para o segundo experimento, os tratamentos foram constituídos pela combinação em esquema fatorial de duas doses (6,72 e 13,44 g e.a. ha-1, equivalentes a 1,0 e 2,0% de deriva) e três épocas de aplicação após o transplante para o campo. Nenhum sintoma visual marcante de fitotoxicidade foi observado dentro da faixa de doses avaliada. Visualmente, alguns dos possíveis efeitos atribuídos à fitotoxicidade ocasionada pela deriva de 2,4-D na cultura do fumo podem estar associados à utilização de antibrotantes. Nenhuma das doses aplicadas no primeiro experimento afetou a produtividade da cultura, nem o aspecto e qualidade das folhas, tendo o fumo tolerado até 4,0% de deriva avaliada. Resultados obtidos no segundo experimento confirmaram esses dados, constatando-se que níveis de deriva de até 2,0% (13,44 g e.a. ha-1), aplicados em três fases após o transplante das mudas para o campo, não causaram qualquer efeito negativo sobre a produtividade da cultura.

Effect of a selective nonsteroidal anti-inflammatory inhibitor of cyclooxygenase-2 on the small bowel of rats

The pathogenesis of nonsteroidal anti-inflammatory drug (NSAID) enteropathy is a complex process involving the uncoupling of mitochondrial oxidative phosphorylation and inhibition of cyclooxygenase (COX). Rofecoxib, a selective inhibitor of COX-2, has shown less gastric damage, but the same beneficial effect is not clear in the case of the small bowel. Fifty-seven male Wistar rats (250-350 g) were divided into three groups (N = 19 each) to evaluate the effect of this NSAID on the rat intestine. The groups received 2.5 mg/kg rofecoxib, 7.5 mg/kg indomethacin or water with 5% DMSO (control) given as a single dose by gavage 24 h before the beginning of the experiment. A macroscopic score was used to quantify intestinal lesions and intestinal permeability was measured using [51Cr]-ethylenediaminetetraacetic acid ([51Cr]-EDTA). The extent of intestinal lesion, indicated by a macroscopic score, was significantly lower when rofecoxib was administered compared to indomethacin (rofecoxib = 0.0 vs indomethacin = 63.6 ± 25.9; P < 0.05) and did not differ from control. The intestinal permeability to [51Cr]-EDTA was significantly increased after indomethacin (control = 1.82 ± 0.4 vs indomethacin = 9.12 ± 0.8%; P < 0.0001), but not after rofecoxib, whose effect did not differ significantly from control (control = 1.82 ± 0.4 vs rofecoxib = 2.17 ± 0.4%; ns), but was significantly different from indomethacin (indomethacin = 9.12 ± 0.8 vs rofecoxib = 2.17 ± 0.4%; P < 0.001). In conclusion, the present data show that rofecoxib is safer than indomethacin in rats because it does not induce macroscopic intestinal damage or increased intestinal permeability.