Polymerization of ethylene by the tris(pyrazolyl)borate titanium(IV) compound immobilized on MAO-modified silicas

The immobilization of soluble catalyst {Tp(Ms)}TiCl3 (Tp(Ms*)HB(3-mesityl-pyrazolyl)(2)(5-mesityl-pyrazolyl)(-)) on silica and MAO-modified silicas containing 4.0, 8.0 and 23.0 wt.% Al/SiO2 yields active supported catalysts for ethylene polymerization. Among the supported catalysts studied by XRF spectroscopy, higher titanium content was obtained using MAO-modified silica containing 8.0 wt.% Al/SiO2 as support. For the ethylene polymerization reactions carried out in hexane at 60degreesC using a combination of triisobutylaluminum (TiBA) and methylaluminoxane (MAO) (1:1), the activities varied between 24.4 and 113.5 kg of PE/mol [Ti] h. The highest activity is reached using MAO-modified silica containing 4.0 wt.% Al/SiO2 as support. The viscosity-average molecular weights ((M) over bar (v)) of the PE's produced with the supported catalysts varying from 1.44 to 9.94 x 10(5) g/mol with melting temperatures in the range of 125-140degreesC. The use of other Lewis acid cocatalysts, including TiBA, diethylaluminium chloride (DEAC), and trimethylaluminum (TMA) resulted also in the formation of active catalysts for ethylene polymerization. However, the activities are lower than that one using a combination of TiBA and MAO. The viscosity-average molecular weights (R,) of PE's are influenced by varying the cocatalysts as well as the Al/Ti molar ratio. The supported catalyst generated in situ under ethylene atmosphere is roughly four times more active than supported one containing 4.0 wt.% Al/SiO2. (C) 2003 Elsevier B.V. All rights reserved.

Flow injection AAS determination of Cd, Cu, and Pb at trace levels in wine using solid phase extraction

A comparative study is reported between C-18 bonded silica gel and powdered polyethylene (PE) as sorbent for Cd, Cu, and Pb determination using ammonium diethyldithiophosphate (ADTP) as the complexing agent in a flow injection system. The complexes were formed in 0.14 mol L-1 HNO3 and processed in a simple flow system comprising a peristaltic pump, a manual injector-commutator, and a sorbent-packed minicolumn. Ethanol was selected as the eluent and analytes in the eluate were determined by flame atomic absorption spectrometry. The optimum concentration of the complexing agent was 0.1% (m/v) ADTP for Cu and Pb determination using either C-18 or PE, and 0.25% (m/v) ADTP for Cd determination using PE. The sample loading flow rates were 5.0, 3.6, and 3.0 mL min(-1) for Cu, Pb, and Cd, respectively. The best elution flow rate was 6.5 mL min(-1). For a 60-sec preconcentration time, the sampling rate was 40 h(-1) and the enrichment factors of 33, 36, and 11 times (C-18) or 18, 22, and 23 times (PE) were obtained for Cu, Pb, and Cd, respectively. The limits of detection (LOD) were 1.6 mug L-1 Cu, 11 mug L-1 Pb, and 2.0 mug L-1 Cd using C-18 or 2.9 mug L-1 Cu, 19 mug L-1 Pb, and 1.0 mug L-1 Cd using PE, respectively. The relative standard deviations (n = 12) were typically <2%, <2%, and <6% for Cd, Cu, and Pb, respectively. The recoveries of Cd, Cu, and Pb added to wine samples varied from 96-99%, 97-102%, and 90-99%, respectively, using C-18 or PE. Accuracy was checked for Cd, Cu, and Pb determination in six wine samples digested by block digestor and open-vessel microwave-assisted digestion systems. The results revealed that C-18 was more efficient for Cu and Pb determination, while PE was the best sorbent for Cd.

Effect of partial preferential orientation and distortions in octahedral clusters on the photoluminescence properties of FeWO4 nanocrystals

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Resposta de plantas daninhas ao óleo fúsel aplicado em pós-emergência inicial e tardia

This work aimed to study weed response to fusel oil rate applied at early and late post-emergence. The following species were studied at late and early post-emergence: Ipomoea hederifolia, Ipomoea quamoclit, Euphorbia heterophylla, Digitaria spp., Cenchrus echinatus and Panicum maximum.. The experiment was arranged in a completely randomized design with six treatments and four replications. Fusel oil, an alcohol distillation byproduct, was applied at rates of 50, 125, 250, 375 and 500 L ha(-1), plus control without application. The plots were constituted by polyethylene containers with 3 L capacity, filled with topsoil land from a fallow area. Visual symptoms of intoxication were verified at 7 and 30 days after application (DAA) and dry weight at 30 DAA. The variables were submitted to variance analysis according to the design, adjusting the data to obtain the dose-response curve by polynomial regression. The studied species were susceptible only to the application of 500 L ha(-1) of fusel oil at early or late plant post-emergence. The species Digitaria spp. was susceptible and E. heterophylla tolerant to fusel oil applied at early post-emergence, while the other species were moderately tolerant. E. heterophylla was susceptible, Digitaria spp., C. echinatus and P. maximum moderately tolerant and I. hederifolia and I. quamoclit tolerant to fusel oil applied at late post-emergence.

Alternatives Panels from Waste Plastics Reinforced With Fibers of Pupunha Palm for Use in Civil Construction and Furniture Industry

In order to cooperate in minimizing the problems of the current and growing volume of waste, this work aims at the production of panels made from industrial waste -thermoplastic (Polypropylene - PP; Polyethylene - PE and Acrylonitrile Butadiene Styrene - ABS) reinforced with agro-industrial waste - pupunha palm waste (shells and sheaths). The properties of the panels were evaluated: density, thickness swelling, water absorption and moisture content. It was used the ASTM D1037; EN 317; and ANSI A208.1 standards regarding particle boards. The best results in physical tests were treatments 1 (100% waste plastic), 6 (60% plastic waste and 40% waste of pupunha) and 7 (70% waste plastic and 30% waste of pupunha). The best results in the mechanical tests were treatments 3 (30% de residuos plasticos e 70% de residuos da pupunha), 4 (40% de residuos plasticos c 60% de residuos da pupunha) and 5 (50% de residuos plasticos e 50% de residuos da pupunha). For mechanical tests it was concluded that the results of modulus of rupture and of modulus of elasticity the best treatments were those with more fibers. In the tensile tests perpendicular to the surface, it is clear that using more waste plastics leads to the best results. It was concluded that the waste can be used as raw material for the production of alternative materials mainly in civil construction and furniture industries, and it can be employed in urban or rural environment, given the concept of eco-efficient products.

Produtividade de pleurotus ostreatus em resíduos da amazônia

The viability of the utilization of wood and agroindustrial residues available in the Amazon region in the formulation of alternative substrates for the cultivation of Pleurotus ostreatus was tested. Thus, two wood residues: marupa sawdust (SIAMP) and pau-de-balsa sawdust (SAPB), and two substrates derived from agroindustrial residues: sugar-cane bagasse (SIACN) and pupunheira stem (SIAPP), were used. These were supplemented with a mixture of rice bran, wheat and corn as protein source, with addition of 2-3% of CaCO(3) for pH correction (6.5). The substrates were placed in polyethylene (HDPE) bags, sterilized at 121 degrees C for 1h and inoculated in a laminar flow chamber. The cultivation was carried out in an axenic way, in a modified atmosphere. The productivity of the substrates was evaluated in relation to the biological efficiency, with the following mean results: 125.60, 99.80%, 94.00 and 64.60% for SIAPP, SIACN, SIAMP and SIAPB, respectively. The high biological efficiency of the substrates and the cultivation process clearly showed the viability of the utilization of the residues, suggesting the commercial cultivation of this mushroom, which may contribute for improving the social and economical conditions and sustainability of the regional biodiversity resources of Amazonia.

Biocompatibility of different intracanal medications in rat buccal submucosa tissue

The aim of this study was to analyze the buccal tissue responses of Wistar rats to 2% chlorhexidine solution, calcium hydroxide and the association of both products. For this purpose, 30 specimens were randomly implanted in the filtrum of the four upper and lower hemiarches with a polyethylene tube containing one of the following substances: 2% chlorhexidine solution, calcium hydroxide and 2% chlorhexidine solution (test groups); calcium hydroxide and distilled water and distilled water (control groups). Ten rats each were distributed according to time interval of evaluation at 7, 15 and 30 days. The histological sections were stained with Harris hematoxylin and eosin. Analysis was per-formed with an optical microscope at x100, x200 and x400 magnifications by an expert examiner blinded to the materials. The sections were classified by scores attributed to inflammatory events and by a ranking determined according to the severity of the inflammation. The results of the inflammatory events and severity ranking were submitted to the Kruskal-Wallis test at a 0.05 level of significance. No statistically significant difference occurred among the tested materials; however, all materials showed a decreased of severity with respect to longer time intervals.

Evaluation of the Effects of Endodontic Materials on Fibroblast Viability and Cytokine Production

Introduction: Recently, a new sealer composed of Portland cement named Endo-CPM-Sealer was developed. The aim of this study was to investigate the effects of Endo-CPM-Sealer (EGEO SRL, Buenos Aires, Argentina), Sealapex (Sybron Endo, Glendora, CA), and Angelus MTA (Angelus, Londrina, Brazil) on cell viability and cytokine (interleukin [IL]-1 beta and IL-6) production by mouse fibroblasts. Methods: Millipore culture plate inserts with polyethylene tubes filled with materials were placed into 24-well cell culture plates with mouse fibroblasts. Cells cultured with only empty polyethylene tubes were used as the control. After 24 hours, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay was used to evaluate the cell viability. For cytokine assay, mouse fibroblasts were incubated in 24-well flat-bottom plates with set material disks at the bottom. Cells cultured without the material disks served as the negative control. After 24 hours of incubation, culture media were collected for cytokine evaluation by using an enzyme-linked immunosorbent assay. The data were statistically analyzed by analysis of variance and Bonferroni correction. Results: Endo-CPM-Sealer, Sealapex, and Angelus MTA did not inhibit the cell viability. All materials induced IL-6 releasing, but the amount was not statistically significant compared with the control group. Angelus MTA induced IL-1 beta releasing significantly more than the control. Conclusions: All materials were not considered cytotoxic in fibroblast culture. (J Endod 2009;35:1577-1579)

Triton X-100 solubilized bone matrix-induced alkaline phosphatase

1. 1. Solubilized and membrane-bound alkaline phosphatase showed Michaelis-Menten behavior in a wide range of different substrate concentrations. 2. 2. Membrane-bound alkaline phosphatase has a molecular weight of 130,000 and its minimum active configuration comprises two identical subunits of about 65,000. 3. 3. The two forms of the enzyme behave similarly with respect to NaCl, urea and guanidine HCl. 4. 4. Catalytic groups have pK values of about 8.5 and 9.7 for both membrane-bound and solubilized enzyme. © 1987.

Effect of water stress on seed germination and seedling growth in Oryza sativa L.

The effect of water stress induced by application of polyethylene glycol 6000 during seed germination and seedling growth of Oryza sativa L. cv. IAC 165 was analysed. The seed germination was inhibited by the decrease in the water potential of the medium, the inhibition being greater under white light than under continuous darkness. When the seedling was submitted to water stress (-0.51 MPa) white light inhibited growth of root, coleoptile-and leaf, while under no stress conditions white light caused increase in growth of root and leaf and only inhibition of coleoptile growth. © 1990 Kluwer Academic Publishers.

Increased oxygen radical and high-dietary-carbohydrate pancreatic damage.

These data suggest that an improved understanding of the relationship between high dietary carbohydrate and the rate of lipid peroxidation may give some insight into possible treatment modalities for pancreatic damages and may shed light on molecular mechanisms underlying certain pathological processes. High dietary carbohydrate lesions are age related and induced alterations on ceruloplasmin, phospholipids, total proteins, copper and zinc serum levels. Significantly increased serum and pancreatic amylase, and lipoperoxide determinations were observed in 20 month old rats. Cu-Zn superoxide dismutase was decreased in these animals. Daily injection of Cu-Zn superoxide dismutase conjugated with polyethylene glycol (SOD-PEG) prevented the serum and pancreatic changes, indicating that superoxide radical is an important intermediate to high dietary carbohydrate lesion.