APONTAMENTOS ACERCA DA DISCUSS��O SOBRE A INTRODU����O DAS EMPRESAS DE CELULOSE NOS PAMPAS GA��CHOS: PARA ONDE VAI A FRONTEIRA SANT��ANA DO LIVRAMENTO E RIVERA?

Os Munic��pios de Sant��Ana do Livramento ��� RS - Brasil e Rivera - Uruguai, instaladas no cora����o dos pampas ga��chos, apresentam uma paisagem que se caracteriza por uma vastid��o de campos, coxilhas e gado, tem sua hist��ria associada a economia ganadeira e a cultura das gentes que habitam esse pampa, o ga��cho e sua viv��ncia campeira s��mbolo de uma cultura que supera as barreiras da nacionalidade e das fronteiras impostas pelos colonizadores. Os pampas e seus habitantes passam por uma transforma����o profunda que est�� associada a decad��ncia da economia ganadeira e a ascens��o da economia madeireira. Cada vez mais observa-se a planta����o de grandes extens��es de terras com pinus e eucaliptus e a implanta����o, muitas vezes conflituosa, de empresas de celulose em locais onde antes reinavam os frigor��ficos. O presente trabalho tem o objetivo de analisar o processo de substitui����o da economia ganadeira pela introdu����o da economia madeireira nessas cidades e avaliar as implica����es sociais, econ��micas, culturais e ambientais atrav��s de um extenso levantamento bibliogr��fico, de pesquisas junto a ��rg��os governamentais e de trabalhos de campo que permitam compreender as transforma����es atuais, as tend��ncias de reprodu����o do grande capital associado ao latif��ndio e as alternativas e formas de resist��ncia a esse modelo hegem��nico de ���desenvolvimento��� na fronteira.��

Celulose de fibra longa a partir de sorgo biomassa, um significativo potencial para o setor de papel e celulose na regi��o Centro-Oeste.

2016

Thermal performance of sisal fiber-cement roofing tiles for rural constructions

Roofing provides the main protection against direct solar radiation in animal housing. Appropriate thermal properties of roofing materials tend to improve the thermal comfort in the inner ambient. Nonasbestos fiber-cement roofing components reinforced with cellulose pulp from sisal (Agave sisalana) were produced by slurry and dewatering techniques, with an optional addition of polypropylene fibers. Nonasbestos tiles were evaluated and compared with commercially available asbestos-cement sheets and ceramic tiles (frequently chosen as roofing materials for animal housing). Thermal conductivity and thermal diffusivity of tiles were determined by the parallel hot-wire method, along with the evaluation of the downside surface temperature. Cement-based components reinforced with sisal pulp presented better thermal performance at room temperature (25��C), while those reinforced with sisal pulp added by polypropylene fibers presented better thermal performance at 60��C. Non-asbestos cement tiles provided more efficient protection against radiation than asbestos corrugated sheets.

Adsorption of amyloglucosidase from Aspergillus niger NRRL 3122 using ion exchange resin

Amyloglucosidase enzyme was produced by Aspergillus niger NRRL 3122 from solid-state fermentation, using deffated rice bran as substrate. The effects of process parameters (pH, temperature) in the equilibrium partition coefficient for the system amyloglucosidase - resin DEAE-cellulose were investigated, aiming at obtaining the optimum conditions for a subsequent purification process. The highest partition coefficients were obtained using 0.025M Tris-HCl buffer, pH 8.0 and 25��C. The conditions that supplied the highest partition coefficient were specified, the isotherm that better described the amyloglucosidase process of adsorption obtained. It was observed that the adsorption could be well described by Langmuir equation and the values of Qm and Kd estimated at 133.0 U mL-1 and 15.4 U mL-1, respectively. From the adjustment of the kinetic curves using the fourth-order Runge-Kutta algorithm, the adsorption (k1) and desorption (k2) constants were obtained through optimization by the least square procedure, and the values calculated were 2.4x10-3 mL U-1 min-1 for k1 and 0.037 min-1 for k2 .

Thermal decomposition of mercerized linter cellulose and its acetates obtained from a homogeneous reaction

Cellulose acetates with different degrees of substitution (DS, from 0.6 to 1.9) were prepared from previously mercerized linter cellulose, in a homogeneous medium, using N,N-dimethylacetamide/lithium chloride as a solvent system. The influence of different degrees of substitution on the properties of cellulose acetates was investigated using thermogravimetric analyses (TGA). Quantitative methods were applied to the thermogravimetric curves in order to determine the apparent activation energy (Ea) related to the thermal decomposition of untreated and mercerized celluloses and cellulose acetates. Ea values were calculated using Broido's method and considering dynamic conditions. Ea values of 158 and 187 kJ mol-1 were obtained for untreated and mercerized cellulose, respectively. A previous study showed that C6OH is the most reactive site for acetylation, probably due to the steric hindrance of C2 and C3. The C6OH takes part in the first step of cellulose decomposition, leading to the formation of levoglucosan and, when it is changed to C6OCOCH3, the results indicate that the mechanism of thermal decomposition changes to one with a lower Ea. A linear correlation between Ea and the DS of the acetates prepared in the present work was identified.

Some aspects of acetylation of untreated and mercerized sisal cellulose

We report here on some aspects of the acetylation in LiCl/N,N-dimethylacetamide, DMAc, of untreated and mercerized sisal cellulose, hereafter designated as sisal and M-sisal, respectively. Fiber mercerization by NaOH solution has resulted in the following changes: 29.9% decrease in the index of crystallinity; 16.2% decrease in the degree of polymerization and 9.3% increase in α-cellulose content. A light scattering study of solutions of sisal, M-sisal, microcrystalline and cotton celluloses in LiCl/DMAc has shown that they are present as aggregates, with (an apparent) average aggregation numbers of 5.2, 3.2, 9.8, and 35.3, respectively. The presence of these aggregates affects the accessibility of cellulose during its functionalization. A study of the evolution of the degree of substitution, DS, of cellulose acetate as a function of reaction time showed an increase up to 5 h, followed by a decrease at 7 h. Possible reasons for this decrease are discussed. As expected, M-sisal gave a higher DS that its untreated counterpart.

Hybrid layer-by-layer assembly based on animal and vegetable structural materials: multilayered films of collagen and cellulose nanowhiskers

Layer-by-layer (LBL) assembly was used to combine crystalline rod-like nanoparticles obtained from a vegetable source, cellulose nanowhiskers (CNWs), with collagen, the main component of skin and connective tissue found exclusively in animals. The film growth of the multilayered collagen/CNW was monitored by UV-Vis spectroscopy and ellipsometry measurements, whereas the film morphology and surface roughness were characterized by SEM and AFM. UV-Vis spectra showed the deposition of the same amount of collagen, 5 mg m(-2), in each dipping cycle. Ellipsometry data showed an increment in thickness with the number of layers, and the average thickness of each bilayer was found to be 8.6 nm. The multilayered bio-based nanocomposites were formed by single layers of densely packed CNWs adsorbed on top of each thin collagen layer where the hydrogen bonding between collagen amide groups and OH groups of the CNWs plays a mandatory role in the build-up of the thin films. The approach used in this work represents a potential strategy to mimic the characteristics of natural extracellular matrix (ECM) which can be used for applications in the biomedical field.

Effect of fibre morphology on flocculation of fibre-cement suspensions

The objective of the present research was to evaluate the effect of fibre morphology (e.g., length, width, fibrillation, broken ends, content of fines and number of fibres per gram) on flocculation and drainage properties of fibre-cement suspensions and on physical properties of the fibre-cement composites. Mechanical refining was used to change the morphological properties of Eucalyptus and Pinus pulps. Results show that the mechanical refining increased the size of the formed flocs and decreased the concentration of free small particles (with dimensions between 1 and 20 pm) as a consequence of the increased fibrillation and content of fines, which increased the capacity of the fibres to capture the mineral particles. High levels of refining were necessary for Pinus pulp to obtain cement retention values similar to those obtained by unrefined Eucalyptus pulp. This is due to the higher number of fibres per gram in Eucalyptus pulp than in Pinus pulp. Pulp refining improved the packing of the particles and, although decreased the drainage rate. it contributed to a less porous structure, which improved the microstructure of the composite. (C) 2009 Elsevier Ltd. All rights reserved.

TOXICITY EVALUATION AS A TOOL TO ASSES THE PERFORMANCE OF AN ANAEROBIC IMMOBILIZED BIOMASS REACTOR

Effluents from pulp mill are usually toxic and mutagenic. This characteristic is mainly a consequence of xenobiotic compounds that are formed during the process. Global parameters such as chemical oxidation demand, total organic carbon and others, do not permit identify whether the toxic potential was remedied by the treatments or not. The objective of this research was to evaluate the performance of an horizontal-flow anaerobic immobilized biomass reactor (HAIB) treating the bleaching effluent from a Kraft pulp mill using toxicological (Daphnia similis - Ceriodaphnia sdvestrii) mutagenicity and citotoxicological assays (Allium cepa L). The results showed high sensibility of the test-organisms and capability of the anaerobic reactor to remove compounds that are exerting toxic and mutagenic effects. The bioassays represented an attractive alternative to water quality analyzes and the performance evaluation of treatments.

THE INFLUENCE OF VIBRISSAL SOMATOSENSORY PROCESSING IN RAT SUPERIOR COLLICULUS ON PREY CAPTURE

The lateral part of intermediate layer of superior colliculus (SCI) is a critical substrate for successful predation by rats. Hunting-evoked expression of the activity marker Fos is concentrated in SCI while prey capture in rats with NMDA lesions in SCI is impaired. Particularly affected are rapid orienting and stereotyped sequences of actions associated with predation of fast moving prey. Such deficits are consistent with the view that the deep layers of SC are important for sensory guidance of movement. Although much of the relevant evidence involves visual control of movement, less is known about movement guidance by somatosensory input from vibrissae. Indeed, our impression is that prey contact with whiskers is a likely stimulus to trigger predation. Moreover, SCI receives whisker and orofacial somatosensory information directly from trigeminal complex, and indirectly from zona incerta, parvicelular reticular formation and somatosensory barrel cortex. To better understand sensory guidance of predation by vibrissal information we investigated prey capture by rats after whisker removal and the role of superior colliculus (SC) by comparing Fos expression after hunting with and without whiskers. Rats were allowed to hunt cockroaches, after which their whiskers were removed. Two days later they were allowed to hunt cockroaches again. Without whiskers the rats were less able to retain the cockroaches after capture and less able to pursue them in the event of the cockroach escaping. The predatory behaviour of rats with re-grown whiskers returned to normal. In parallel, Fos expression in SCI induced by predation was significantly reduced in whiskerless animals. We conclude that whiskers contribute to the efficiency of rat prey capture and that the loss of vibrissal input to SCI, as reflected by reduced Fos expression, could play a critical role in predatory deficits of whiskerless rats. (C) 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

Structural and morphological anomalies in magnetosomes: possible biogenic origin for magnetite in ALH84001

We report biogenic magnetite whiskers, with axial ratios of 6: 1, elongated in the [1 1 1]. [1 1 2] and [1 0 0] directions, resembling the magnetite whiskers detected in the Martian meteorite ALH84001 by Bradley ct nl., and interpreted by those authors as evidence of vapour-phase (abiogenic) growth. Magnetosomal whiskers with extended defects consistent with screw dislocations and magnetosomes resembling flattened twinned platelets, as well as other twinning phenomena and other structural defects, are also reported here. Magnetosomes with teardrop-shaped. cuboidal. irregular and jagged structures similar to those detected in ALH84001 by McKay et al.. coprecipitation of magnetite possibly with amorphous calcium carbonate, coprecipitation of magnetite possibly with amorphous silica, the incorporation of titanium in volutin inclusions and disoriented arrays of magnetosomes are also described. These observations demonstrate that the structures of the magnetite particles in ALH84001. their spatial arrange ment and coprecipitation with carbonates and proximity to silicates are consistent with being biogenic. Electron-beam-induced flash-melting of magnetosomes produced numerous screw dislocations in the (1 1 1). (1 0 0) and (1 1 0) lattice planes and induced fusion of platelets. From this, the lack of screw dislocations reported in the magnetite particles in ALH84001 (McKay et al.. and Bradley et al.) indicates that they have a low-temperature origin.

Freeform fabrication of aluminum metal-matrix composites

A series of metal-matrix composites were formed by extrusion freeform, fabrication of a sinterable aluminum alloy in combination with silicon carbide particles and whiskers, carbon fibers, alumina particles, and hollow flyash cenospheres. Silicon carbide particles were most successful in that the composites retained high density with up to 20 vol% of reinforcement and the strength approximately doubles over the strength of the metal matrix alone. Comparison with simple models suggests that this unexpectedly high degree of reinforcement can be attributed to the concentration of small silicon carbide particles around the larger metal powder. This fabrication method also allows composites to be formed with hollow spheres that cannot be formed by other powder or melt methods.

Caracteriza����o da ontogen��tica do pau-brasil

As a����es de reflorestamento com o pau-brasil (Caesalpinia echinata Lam.) depende de informa����es de suas caracter��sticas ecofisiol��gicas sujeitas ��s varia����es ontogen��ticas e ambientais. O objetivo desse trabalho foi caracterizar alguns aspectos morfol��gicos, anat��micos, fisiol��gicos e estruturais de parede celular de C. echinata nas fases juvenil, jovem e adulto em condi����es naturais em um fragmento da Floresta Atl��ntica. Foi analisada a biometria, concentra����o de nutrientes e dos pigmentos cloroplast��dicos dos foli��lulos, anatomia foliar e do xilema secund��rio do caule e a constitui����o dos pol��meros estruturais de parede celular. Os indiv��duos juvenis localizados no estrato inferior da floresta se destacaram pela maior ��rea foliar espec��fica e maiores teores de pigmentos cloroplast��dicos bem como pelas maiores dimens��es de suas c��lulas guardas associado ��s maiores concentra����es de K e Ca foliar. Estruturalmente, os indiv��duos juvenis apresentaram menores elementos de vasos e teores de lignina. Os indiv��duos jovens apresentaram valores intermedi��rios das vari��veis analisadas. J�� os indiv��duos adultos, cujas copas alcan��avam o dossel, se destacaram pelo maior espessamento do limbo, da cut��cula e do par��nquima lacunoso, teor de ��gua foliar, densidade estom��tica e teor de lignina foliar e caulinar cuja capacidade de s��ntese foi associada ao maior teor de P foliar. O conte��do de celulose foliar e caulinar n��o variou entre as diferentes fases ontogen��ticas. As hemiceluloses s��o do tipo xilanos com possibilidade de presen��a de xiloglucano dada a maior fra����o de xilose (��12% MS) e galactose (��1% MS). A glucose foi o monossacar��deo mais representativo (��40% MS) sem diferen��as ontogen��ticas. As diferen��as morfol��gicas, anat��micas, fisiol��gicas e estruturais parecem, tamb��m, estarem sob controle da irradi��ncia mais intensa na copa dos indiv��duos adultos. Os resultados denotam que o plantio consorciado com esp��cies de crescimento r��pido seja a melhor a����o para o reflorestamento de C. echinata.

Compara����o de custos de implanta����o de eucalipto com res��duo celul��sico em substitui����o ao fertilizante mineral

A grande expans��o das ind��strias e do mercado consumidor tem provocado, nas ��ltimas d��cadas, a gera����o de elevadas quantidades de res��duos, os quais t��m constitu��do constante preocupa����o econ��mica e ambiental. Objetivou-se, neste trabalho, analisar a viabilidade econ��mica do uso de tr��s doses de composto org��nico, oriundo da compostagem de res��duos da extra����o da celulose, em substitui����o �� aduba����o mineral, na cultura do eucalipto, no munic��pio de Selv��ria, MS. A metodologia de custos adotada foi a do custo operacional total e do custo total. Concluiu-se que, por causa do elevado custo de transporte e aplica����o, a aduba����o org��nica mostrou-se mais onerosa em rela����o �� mineral, sendo sua utiliza����o vi��vel, economicamente, apenas nas proximidades da ind��stria produtora.

Responsabilidade social: ideologia, poder e discurso na l��gica empresarial

O objetivo do artigo �� identificar como uma empresa multinacional de papel e celulose desenvolve programas sociais em uma regi��o compreendida por 47 munic��pios no estado de Minas Gerais. A escolha da empresa X foi definida pela sua import��ncia na ind��stria mineira, bem como pelo destaque dado aos programas sociais da empresa no meio empresarial, que vivencia iniciativas centralizadas de incentivo ao voluntariado. Foi realizada uma pesquisa bibliogr��fica sobre a concep����o da responsabilidade social empresarial e uma pesquisa de campo qualitativa com agentes sociais na regi��o de atua����o da empresa. A metodologia empregada na pesquisa foi constru��da por meio de um conjunto de entrevistas semiestruturadas, utilizando a an��lise do discurso como t��cnica para pontua����o das conclus��es do trabalho. Os resultados demonstram que a pr��tica da responsabilidade social se situa num contexto mais significativo que o mero discurso empresarial.