Spectrophotometric determination of arsenic in soil samples using 2-(5-bromo-2-pyridylazo)-5-di-ethylaminophenol (Br-PADAP)

In this paper, a new, simple and sensitive method for arsenic determination in soil is proposed. This is based on the reduction of silver (I) and iron (III) ions by arsine followed by a complexation reaction of iron (II) with the spectrophotometric reagent Br-PADAP 2-(5-bromo-2-pyridylazo)-5-di-ethylaminophenol. Arsenic determination with a Sandell's sensitivity of 3.1 10-4 cm-2, linear range from 0.1 ��g ml-1 to 2.0 ��g ml-1 (r560 = 0.9995), molar absorptivity of 2.45 10(5) l mol-1 cm-1 and a concentration detection limit of 1.4 ng ml-1 (3s) were obtained using a 10 ml sample volume. Selectivity was increased with the use of EDTA as a masking agent. The proposed method was applied for arsenic determination in the presence of several ions amounts in digested soil samples. The results revealed that antimony (III), mercury (II), germanium (IV), platinum (IV) interferes at all analyzed proportions. The interferences can be easily removed by the use of EDTA. Precision and accuracy obtained were satisfactory with a R.S.D. < 5 %. Recovery of arsenic in soil samples varied from 95.55 to 102.70 % with a mean of 99.63 %. These results demonstrated that the proposed method is applicable for arsenic analysis in different soil samples.

Optimization of NMP extraction in 1, 3-butadiene production line

N-methylpyrrolidone is a powerful solvent for variety of chemical processes due to its vast chemical properties. It has been used in manufacturing processes of polymers, detergents, pharmaceuticals rubber and many more chemical substances. However, it creates large amount of residue in some of these processes which has to be dealt with. Many well known methods such as BASF in rubber producing units have tried to regenerate the solvent at the end of each run, however, there is still discarding of large amount of residue containing NMP, which over time, could cause environmental concerns. In this study, we have tried to optimize regeneration of the NMP extraction from butadiene production. It is shown that at higher temperatures NMP is separated from the residue with close to 90% efficiency, and the solvent residue proved to be the most effective with a 6: 1 ratio.

Produ����o de pain��is de madeira aglomerada de Grevillea robusta A. Cunn. ex R. Br.

Este trabalho teve como objetivo avaliar o comportamento da madeira de Grevillea robusta na produ����o de pain��is de madeira aglomerada. Os pain��is foram produzidos em densidades de 0,60 e 0,80 g/cm&sup3; e conte��do de resina de 6 e 8%. Os resultados de propriedades f��sicas e mec��nicas dos pain��is fabricados com densidade de 0,80 g/cm&sup3; e conte��do de resina de 8% evidenciaram que a madeira de Grevillea robusta pode ser utilizada como fonte alternativa de mat��ria-prima para produ����o de pain��is aglomerados.

EVALUATION OF SUBSTRATES AND AMF SPORULATION IN THE PRODUCTION OF SEEDLINGS OF NATIVE FOREST SPECIES

ABSTRACT The objective of this study was to evaluate organic substrates in the production of canafistula (Peltophorum dubium) (Spreng.) Taub, cutieira (Joannesiaprinceps Vell.), jatoba (Hymenaea courbaril L.) and rubber tree (Hevea brasiliensis M. Arg.) seedlings, native trees with potential use in forest restoration programs. The design was completely randomized with 10 substrate formulations with 4 repetitions of 3 plants for the four species. The evaluated substrates consisted of soil, bovine manure (BM), poultry manure (PM), chemical fertilizer (CF) and sand, in different proportions. The experiment was concluded at the end of 180 days for canafistula, cutieira and rubber and 210 days for jatoba. At the end of these periods, the root (RDM), shoot (SDM) and total (TDM) the dry matters of the seedlings were determined. Quantification of AMF spores and normalization between samples through SPORES/RDM correction were also performed. The Scott-Knott test at 5% probability was applied. Regarding biomass production, only canafistula had significant difference among the tested substrates. In relation to sporulation, the highest values were observed in cutieira and rubber tree in substrate containing PM. The substrates composed of 40 or 50% soil + 20% sand + 30% or 40 PM for canafistula; 50% soil + 20% sand + 30% PM for cutieira; and for jatoba and rubber tree 60% soil + 20% sand + 20% PM, enabled the best results in terms of biomass production in seedlings and AMF sporulation.

NaOCl effect on biofilm produced by Staphylococcus aureus isolated from the milking environment and mastitis infected cows

Biofilms constitute a physical barrier, protecting the encased bacteria from detergents and sanitizers. The objective of this work was to analyze the effectiveness of sodium hypochlorite (NaOCl) against strains of Staphylococcus aureus isolated from raw milk of cows with subclinical mastitis and Staphylococcus aureus isolated from the milking environment (blowers and milk conducting tubes). The results revealed that, in the presence of NaOCl (150ppm), the number of adhered cells of the twelve S. aureus strains was significantly reduced. When the same strains were evaluated in biofilm condition, different results were obtained. It was found that, after a contact period of five minutes with NaOCl (150ppm), four strains (two strains from milk , one from the blowers and one from a conductive rubber) were still able to grow. Although with the increasing contact time between the bacteria and the NaOCl (150ppm), no growth was detected for any of the strains. Concerning the efficiency of NaOCl on total biofilm biomass formation by each S. aureus strain, a decrease was observed when these strains were in contact with 150 ppm NaOCl for a total period of 10 minutes. This study highlights the importance of a correct sanitation protocol of all the milk processing units which can indeed significantly reduce the presence of microorganisms, leading to a decrease of cow��s mastitis and milk contamination.

Instability of a square sheet under symmetric biaxial loading

An early experiment found that a square rubber sheet under symmetric biaxial loading may not remain square. This curious result has been one of the most instructive examples in finite elasticity. Here thermodynamic considerations are used to analyze this instability.

Estudo comparativo do ac��mulo de massa seca e macronutrientes por plantas de milho var. BR-106 e Brachiaria plantaginea

Foram realizados dois experimentos, em casa de vegeta����o, no Departamento de Biologia Aplicada �� Agropecu��ria da FCAV-UNESP de Jaboticabal, objetivando-se determinar o ac��mulo de massa seca e a distribui����o e ac��mulo de macronutrientes em plantas de milho, no per��odo de outubro de 2000 a fevereiro de 2001, e de capim-marmelada, no per��odo de setembro de 2003 a fevereiro de 2004. Os estudos foram realizados em delineamento experimental inteiramente casualizado, com quatro repeti����es. As plantas cresceram em vasos com capacidade de sete litros - preenchidos com areia de rio lavada e peneirada - e foram irrigadas diariamente com solu����o nutritiva. Os tratamentos foram representados pelas ��pocas de amostragem realizadas a intervalos de 14 dias, a saber: 21, 35, 49, 63, 77, 91, 105, 119 e 133 dias ap��s a emerg��ncia (DAE) das plantas de milho; e 21, 35, 49, 63, 77, 91, 105, 119, 133 e 147 DAE das plantas de capim-marmelada. O ponto de m��ximo ac��mulo te��rico de massa seca deu-se aos 122 DAE para o milho (143,8 g por planta) e aos 143 DAE para o capim-marmelada (23,9 g por planta). A taxa de absor����o di��ria dos macronutrientes atingiu maiores valores entre 71 e 104 DAE para o milho e entre 96 e 111 DAE para a planta daninha. Levando-se em conta a m��dia dos valores de pontos de inflex��o observados na cultura do milho, aos 85 DAE uma planta de milho acumula, teoricamente, 83,0 g de massa seca; 788,9 mg de N; 137,5 mg de P; 1.385,6 mg de K; 551,8 mg de Ca; 217,9 mg de Mg; e 92,5 mg de S. Enquanto que, no mesmo per��odo, uma planta de B. plantaginea acumula, teoricamente, 9,6 g de massa seca; 127,8 mg de N; 15,9 mg de P; 217,3 mg de K; 43,9 mg de Ca; 58,3 mg de Mg; e 15,8 mg de S.

Sistemas reprodutivos e poliniza����o em esp��cies simp��tricas de Erythroxylum P. Br. (Erythroxylaceae) do Brasil

Foram investigadas a biologia reprodutiva e a poliniza����o de Erythroxylum campestre St. Hil., E. suberosum St. Hil. e E. tortuosum Mart., ocorrentes na Fazenda ��gua Limpa, Bras��lia, DF. Estas esp��cies s��o simp��tricas, comumente encontradas em cerrados abertos e florescem em m��dia quatro meses por ano. As tr��s esp��cies s��o dist��licas, isto ��, apresentam flores com estiletes longos (longistiladas) e flores com estiletes curtos (brevistiladas), ambas com estames em posicionamentos correspondentes. As flores s��o similares, pequenas, suavemente perfumadas, de cor creme claro, diurnas, produtoras de n��ctar (concentra����o m��dia de sacarose de 20,2%) e duram um dia. Os testes de poliniza����o artificial revelaram que E. suberosum e E. tortuosum s��o auto-incompat��veis e s�� formaram frutos de poliniza����es leg��timas. Por��m, E. campestre �� parcialmente auto-compat��vel. Em todas as esp��cies a produ����o de frutos resultantes de poliniza����o natural, foi maior que aquela de poliniza����es artificiais. Com exce����o de E. campestre, os estudos de microscopia de fluoresc��ncia revelaram que os tubos pol��nicos resultantes de auto-poliniza����o em flores longistiladas foram bloqueados no estilete e em flores brevistiladas no estigma. As tr��s esp��cies foram indistintamente visitadas por 14 esp��cies de vespas, 14 de abelhas e duas de d��pteros. As vespas dos g��neros Brachygastra, Polistes, Polybia e Pepsis foram consideradas polinizadores efetivos devido �� efici��ncia ao contactarem os estigmas. As abelhas Trigona spinipes e Apis mellifera foram consideradas polinizadores ocasionais.

Lectotypifications in Ditassa R.Br. (Apocynaceae: Asclepiadoideae)

As results of a revision of the Brazilian species of Ditassa, lectotypes for D. endoleuca Schltr., D. pauciflora Decne. and D. ramosa E. Fourn. (= D. blanchetii Decne.) are designated.

Human_Leishmaniasis@cytokines.bahia.br

The cell-mediated immune response is critical in the resistance to and recovery from leishmaniasis. Cytokines are central elements in mounting an immune response and have received a great deal of attention in both human and experimental leishmaniasis. IFN-<FONT FACE="Symbol">g</font> is responsible for macrophage activation leading to leishmanicidal mechanisms. Understanding the balance of cytokines that lead to enhanced production of or synergize with IFN-<FONT FACE="Symbol">g</font>, and those cytokines that counterbalance its effects is fundamental for developing rational immunotherapeutic or immunoprophylactic approaches to leishmaniasis. Here we focus on the cytokine balance in human leishmaniasis, particularly IL-10 as an IFN-<FONT FACE="Symbol">g</font> opposing cytokine, and IL-12 as an IFN-<FONT FACE="Symbol">g</font> inducer. The effects of these cytokines were evaluated in terms of several parameters of the human immune response. IL-10 reduced lymphocyte proliferation, IFN-<FONT FACE="Symbol">g</font> production and cytotoxic activity of responsive human peripheral blood mononuclear cells. Neutralization of IL-10 led to partial restoration of lymphoproliferation, IFN-<FONT FACE="Symbol">g</font> production and cytotoxic activity in unresponsive visceral leishmaniasis patients. IL-12 also restored the responses of peripheral blood mononuclear cells from visceral leishmaniasis patients. The responses obtained with IL-12 are higher than those obtained with anti-IL-10, even when anti-IL-10 is combined with anti-IL-4

4-Aminopyridine inhibits the neuromuscular effects of nitric oxide and 8-Br-cGMP

The effects induced by nitric oxide (NO) in different tissues depend on direct and/or indirect interactions with K+ channels. The indirect interaction of NO is produced by activation of guanylyl cyclase which increases the intracellular cGMP. Since NO, cGMP and 4-aminopyridine alone induce tetanic fade and increase amplitude of muscular contractions in isolated rat neuromuscular preparations, the present study was undertaken to determine whether or not the neuromuscular effects of NO and 8-Br-cGMP can be modified by 4-aminopyridine. Using the phrenic nerve and diaphragm muscle isolated from male Wistar rats (200-250 g), we observed that L-arginine (4.7 mM) and 8-Br-cGMP (18 ��M), in contrast to D-arginine, induced an increase in the amplitude of muscle contraction (10.5 �� 0.7%, N = 10 and 8.0 �� 0.7%, N = 10) and tetanic fade (15 �� 2.0%, N = 8 and 11.6 �� 1.7%, N = 8) at 0.2 and 50 Hz, respectively. N G-nitro-L-arginine (4 mM, N = 8 and 8 mM, N = 8) antagonized the effects of L-arginine. 4-Aminopyridine (1 and 10 ��M) caused a dose-dependent increase in the amplitude of muscle contraction (15 �� 1.8%, N = 9 and 40 �� 3.1%, N = 10) and tetanic fade (17.7 �� 3.3%, N = 8 and 37.4 �� 1.3%, N = 8). 4-Aminopyridine (1 ��M, N = 8) did not cause any change in muscle contraction amplitude or tetanic fade of preparations previously paralyzed with d-tubocurarine or stimulated directly. The effects induced by 4-aminopyridine alone were similar to those observed when the drug was administered in combination with L-arginine or 8-Br-cGMP. The data suggest that the blockage of K+ channels produced by 4-aminopyridine inhibits the neuromuscular effects induced by NO and 8-Br-cGMP. Therefore, the presynaptic effects induced by NO seem to depend on indirect interactions with K+ channels.

Hind limb ischemic preconditioning induces an anti-inflammatory response by remote organs in rats

Ischemic preconditioning (IPC), a strategy used to attenuate ischemia-reperfusion injury, consists of brief ischemic periods, each followed by reperfusion, prior to a sustained ischemic insult. The purpose of the present study was to evaluate the local and systemic anti-inflammatory effects of hind limb IPC in male Wistar rat (200-250 g) models of acute inflammation. IPC was induced with right hind limb ischemia for 10 min by placing an elastic rubber band tourniquet on the proximal part of the limb followed by 30 min of reperfusion. Groups (N = 6-8) were submitted to right or left paw edema (PE) with carrageenan (100 ��g) or Dextran (200 ��g), hemorrhagic cystitis with ifosfamide (200 mg/kg, ip) or gastric injury (GI) with indomethacin (20 mg/kg, vo). Controls received similar treatments, without IPC (Sham-IPC). PE is reported as variation of paw volume (mL), vesical edema (VE) as vesical wet weight (mg), vascular permeability (VP) with Evans blue extravasation (��g), GI with the gastric lesion index (GLI; total length of all erosions, mm), and neutrophil migration (NM) from myeloperoxidase activity. The statistical significance (P < 0.05) was determined by ANOVA, followed by the Tukey test. Carrageenan or Dextran-induced PE and VP in either paw were reduced by IPC (42-58.7%). IPC inhibited VE (38.8%) and VP (54%) in ifosfamide-induced hemorrhagic cystitis. GI and NM induced by indomethacin were inhibited by IPC (GLI: 90.3%; NM: 64%). This study shows for the first time that IPC produces local and systemic anti-inflammatory effects in models of acute inflammation other than ischemia-reperfusion injury.

A forced running wheel system with a microcontroller that provides high-intensity exercise training in an animal ischemic stroke model

We developed a forced non-electric-shock running wheel (FNESRW) system that provides rats with high-intensity exercise training using automatic exercise training patterns that are controlled by a microcontroller. The proposed system successfully makes a breakthrough in the traditional motorized running wheel to allow rats to perform high-intensity training and to enable comparisons with the treadmill at the same exercise intensity without any electric shock. A polyvinyl chloride runway with a rough rubber surface was coated on the periphery of the wheel so as to permit automatic acceleration training, and which allowed the rats to run consistently at high speeds (30 m/min for 1 h). An animal ischemic stroke model was used to validate the proposed system. FNESRW, treadmill, control, and sham groups were studied. The FNESRW and treadmill groups underwent 3 weeks of endurance running training. After 3 weeks, the experiments of middle cerebral artery occlusion, the modified neurological severity score (mNSS), an inclined plane test, and triphenyltetrazolium chloride were performed to evaluate the effectiveness of the proposed platform. The proposed platform showed that enhancement of motor function, mNSS, and infarct volumes was significantly stronger in the FNESRW group than the control group (P<0.05) and similar to the treadmill group. The experimental data demonstrated that the proposed platform can be applied to test the benefit of exercise-preconditioning-induced neuroprotection using the animal stroke model. Additional advantages of the FNESRW system include stand-alone capability, independence of subjective human adjustment, and ease of use.