Thesis (Ph. D.)--University of Washington. / Bibliography: l. 323-358.

Thesis (M.F.A.)--Rochester Institute of Technology, 1991. / Typescript. Includes bibliographical references (leaf 76).

Made available in DSpace on 2015-12-04T11:45:12Z (GMT). No. of bitstreams: 1 Regina_Galhardi_de_Camargo.pdf: 603725 bytes, checksum: c70c2b715bbf9202b54c36c60a7cfded (MD5) Previous issue date: 2005-08-30 / Due to difficulties faced by the Brazilian official social security, the government has been supporting the expansion of the private social security. Through regulatory and legal agencies, the Brazilian official social security has been being given more transparency, security and flexibility. As part of the situation, the pension funds, also named EFPC, have the basic function of providing social security complementary benefits to the employees of an enterprise (or sponsor). As a way of guaranteeing the future payment of offered benefits to participants, the complementary pension entities manage investments which arise from sponsors and employees?? contributions. Those investments are associated in portfolios, and their arrangement limits and diversification established by SPC. According to ABRAPP data, on February 2005, Brazilian pension funds invested eighty one billion reais in the application of resources in a variable income segment, 31% of their total investments. The aim of this work is to propose a model for the investments portfolio in variable income of the pension funds, whose building was made possible through a bibliographical research. This research had the objective to provide a theoretical and specific review of risk, value, valuation and opportunity cost. The contribution of this work is the transition from the theoretical model to the practical application The model was applied to enterprises connected to Previ??s investments portfolio of variable income, and the conclusion is: through the use of such a model, managers of pension funds can sustain their acquisition, maintenance and investments write off decisions, parts of that entities??variable income portfolio. / Diante das dificuldades enfrentadas no Brasil pela previd??ncia oficial, o Governo tem incentivado a expans??o do sistema previdenci??rio privado, conferindo-lhe, por meio dos ??rg??os normativos e legais, maior transpar??ncia, seguran??a e flexibilidade. Nesse cen??rio, inserem-se os fundos de pens??o, tamb??m chamados de entidades fechadas de previd??ncia complementar - EFPC, que t??m a fun????o b??sica de propiciar benef??cios previdenci??rios complementares aos empregados de uma empresa, chamada de patrocinadora. Para garantir o pagamento futuro dos benef??cios oferecidos aos participantes, as entidades de previd??ncia complementar gerenciam os investimentos decorrentes do patrim??nio formado pelas contribui????es dos patrocinadores e empregados. Esses investimentos s??o agregados em carteiras, cujos limites de composi????o e diversifica????o s??o estabelecidos pela SPC - Secretaria da Previd??ncia Complementar. Conforme dados da ABRAPP - Associa????o Brasileira das Entidades Fechadas de Previd??ncia Complementar, em fevereiro de 2005, os fundos de pens??o brasileiros possu??am cerca de R$ 81 bilh??es de recursos alocados no segmento de renda vari??vel, o que significava 31% da totalidade de seus investimentos. Este trabalho prop??e um modelo para a carteira de investimentos em renda vari??vel dos fundos de pens??o, cuja constru????o deu-se a partir de uma pesquisa bibliogr??fica, objetivando uma revis??o te??rica e espec??fica sobre os temas: risco, valor, avalia????o de empresas e custo de oportunidade. O modelo foi aplicado para empresas que fazem parte da carteira de investimentos de renda vari??vel da Previ - Caixa de Previd??ncia dos Funcion??rios do Banco do Brasil, e ?? a conclus??o do trabalho. Ou seja, por meio da ado????o do modelo constru??do, ?? poss??vel aos gestores dos fundos de pens??o modelar as decis??es de aquisi????o, manuten????o ou baixa de investimentos que comp??em a carteira renda vari??vel dessas entidades.

Submitted by Elba Lopes (elba.lopes@fecap.br) on 2018-06-04T20:05:13Z No. of bitstreams: 2 Fabrizio Aguiar de Souza Scommegna.pdf: 287416 bytes, checksum: e17218bb03b78e9e9454efa303f5f345 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-06-04T20:05:13Z (GMT). No. of bitstreams: 2 Fabrizio Aguiar de Souza Scommegna.pdf: 287416 bytes, checksum: e17218bb03b78e9e9454efa303f5f345 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-02-23 / Brazilian pension funds have allocated 90% of their investments in fixed income and equity. The insertion of alternative investments, such as commodities, can improve the risk / return relationship since it carries zero correlation in comparison with the others. To verify if this new category can be considered as investment in a portfolio with the best risk / return ratio, the Sharpe Ratio was used to compare optimal portfolios that used commodities with others that did not use it. As a robustness test, we applied Ledoit and Wolf (2008), which compares two Sharpe Ratios in non-normal time series. The period considered is 2009 to 2017, we also observed periods of three years. The results showed that fixed income maintains high returns with low volatility and the portfolios resorts it, equities was not relevant for any period analyzed and investments in commodities were considered in the period of high interest of the economy. The Sharpe Ratio of that period was statistically higher than the traditional portfolio. / Os fundos de pens??o brasileiros t??m alocado 90% dos seus recursos em investimentos na classe de ativos de renda fixa e renda vari??vel. A inser????o de investimentos alternativos, como commodities, pode melhorar a rela????o risco/retorno dado que carrega correla????o nula em compara????o com as demais. Para verificar se essa nova categoria pode ser considerada como investimento em uma carteira com a melhor rela????o risco/retorno, fez-se o uso do ??ndice de Sharpe para comparar carteiras ??timas que utilizaram commodities com outras que n??o se utilizaram disso. Como teste de robustez usou-se de Ledoit e Wolf (2008) que compara dois ??ndices de Sharpe em s??ries temporais n??o normais. Al??m de investigar o per??odo de 2009 a 2017, foram observados tamb??m os tri??nios compreendidos nessa ??poca. Os resultados demonstraram que a renda fixa mant??m altos retornos com baixa volatilidade e as carteiras utilizaram bastaste dessa, o segmento de mercado renda vari??vel n??o foi relevante para nenhum per??odo analisado e os investimentos em commodities foram considerados no per??odo de alta de juros da economia. O ??ndice de Sharpe desse per??odo foi estatisticamente maior que a carteira tradicional.

Bakgrund: Akupunktur är en gammal behandlingsmetod, beräknad ungefär 4100 år gammal och kommer från Kina. Elektroakupunktur är en något nyare behandlingsmetod där man för ström mellan nålarna. Denna behandlingsmetod används främst av fysioterapeuter. Behandlingarna som fysioterapeuten utför kräver ett vetenskapligt stöd, därför finns ett behov att granska den litteratur som behandlingsmetoden grundas på. Inom forskning och verksamhet använder man olika namn för denna metod, både “electroacupuncture” och “percutaneouselectricalnervestimulation” (PENS). Ryggsmärta är ett vanligt problem bland världens befolkning, det är beräknat att upptill 70% av befolkningen kommer någon gång i sitt liv uppleva ryggssmärta. Det är även beräknat att vara den vanligaste smärtförekomsten. Om elektroakupunktur fungerar mot ländryggssmärta kan terapeuter använda denna behandlingsmetod. Syfte: Syftet med denna studie var att undersöka vilket vetenskapligt stöd det finns för elektroakupunktur som behandlingsmetod vid ländryggssmärta. Metod: En systematisk sökning utfördes i databaserna CinAHL, PubMed, PEDro, Scopus och Web of Science angående elektroakupunktur och ländryggssmärta. Sökorden som användes var “electroacupuncture”, “lowback pain ”, “percuteaneous electricalnervestimulation” och “randomized controlled trial”. Resultat: Sammanlagt 15 RCT – studier inkluderades i denna studie. Sammanlagt 11 av 15 studier fann signifikanta skillnader i resultat. 8 studier behandlade kronisk ländryggssmärta, 4 behandlade diskogena besvär och resterande 3 behandlade andra ryggdiagnoser. Elektroakupunktur har visat ge en smärtlindring vid ländryggssmärta. Konklusion: Samtliga inkluderade studier fann smärtlindring av behandlingen, dock visade inte alla signifikanta skillnader. Det finns även metodologiska brister i den befintliga litteraturen vilket innebär att bör se resultaten kritiskt. Mer forskning inom området behövs.

An optimized method of extraction, an instrumental analysis method and data analysis was proposed for black writing inks based on direct infusion electrospray-mass spectrometry (ESI-MS). The sampling and analysis method is both minimally destructive and able to assess differences in inks from a reference collection of thirty ballpoint, gel, and rollerball inks. The methanol extracts of ink on paper samples were analyzed with three direct infusion (ESI-MS) methods. Each method varied scan voltage negative and positive, ESI fragmentor applied voltage (+120V, +0V, and -120V), and mobile phase additive. Direct infusion ESI-MS analysis, followed by pair-wise comparisons of the observed ion data in binary form allowed inks to be distinguished from each other. The photobleaching of the dye Basic Violet 3 (BV3) in ink-onpaper samples was examined to determine the use of degradation products as a marker of the age of the writing sample. The extent of photobleaching of BV3 was determined using several illumination sources. Pair-wise comparison of observed ion data was able to distinguish 29 of 30 ink samples using the combined three instrumental methods. Out of 435 pair-wise comparisons 429 pairs could be discriminated from each other using the combined three methods. This is a 98.6% discrimination with the combined analysis scheme

<p>Effective enrichments for farm animals are increasingly important to address public concerns about farm animal welfare and improve the welfare of the animals we raise. The public’s concern has increased in recent years as the management and care that farmers give their animals has become more apparent to them. Some of the conditions in which animals are kept are emotionally not appealing to the public. One such condition is farrowing crates for sows and piglets. The sows are confined in a small space with no social contact and cannot perform nesting behaviors. Farrowing crates are widely used though, as they allow farmers to handle piglets without fear of sow aggression, meet individual sow nutritional needs, and personalize care. Piglet mortality due to crushing is also decreased with crate use. Sow welfare in farrowing crates can be improved through environmental enrichments. Enrichments improve welfare by increasing species-specific behaviors, creating a more complex environment, reducing abnormal behaviors, and increasing an animal’s ability to cope with stressful situations. For pigs, different enrichments have been shown to decrease stereotypies, like sham chewing and bar biting, decrease harmful redirected behavior towards pen mates, like tail biting and belly nosing, increased exploratory behavior, and increase positive affect. Straw has been found to be the best enrichment for pigs because it allows them to perform motivational behaviors such as rooting, foraging, and nest building. It is also complex, manipulatable, destructible, and ingestible, which are important attributes of effective enrichments. Unfortunately, straw cannot be used in farms that have slurry systems, as the straw will fall through the slats into the pit below and cause drainage issues. This includes farrowing crates. There have been a few studies on alternative enrichments for sows in crates, like cloth tassels, but they are not as effective as straw and are rarely used on farm.</p> <p> Most enrichments target pigs’ motivations to forage, root, graze, or build nests. Pigs perform other behaviors and may have other motivations that enrichments have not targeted yet. One such behavior is scratching. In a semi-natural environment, pigs will rub against trees and bushes. In confinement, pigs rub on fences, walls, and even allow people to scratch them with their hands. There have been no recorded studies done on scratching enrichment for pigs. Many studies have been done in the dairy industry exploring rotating brushes. These brushes have been implemented successfully on commercial farms and are used by cows to groom and scratch themselves. A similar device may allow pigs to also satisfy their itch. Our aim is to provide scratching enrichment to sows in farrowing crates. Since there have been no studies recorded on scratching enrichment or scratching in pigs in general, several steps had to take place before addressing the topic for sows in crates. The first project’s aim was to see what materials pigs prefer to scratch on and their willingness to use such an enrichment.</p> <p><a> The first project consisted of 2 experiments. Exp. 1 was a pilot study where 5 different materials on scratch posts were presented to a pen of gestating sows. The scratch posts were constructed from polyvinyl chloride (<b>PVC</b>) pipes, boards, and a gate post. Five different materials were attached to the boards: white, soft, long-bristled brushes (<b>White Brush</b>), red, hard, short-bristled brush (<b>Red Brush</b>), black, short-bristled, astro-turf-like mat (<b>Plastic Mat</b>), colorful coir, hard, short-bristled mat (<b>Fiber Mat</b>), and blue, plastic, large-round-bristled combs (<b>Plastic Combs</b>). The 8 sows received all 5 scratch posts in their pen for a habituation day and then 7 d of testing. During testing, video was continuously recorded from which 2 behaviors were collected; scratching and interacting. Sows scratched the most on Plastic Mat followed by Fiber Mat, Plastic Combs, and Red Brush. The White Brush was scratched on the least. The top 3 preferences were chosen to proceed to Exp. 2.</a></p> <p> Experiment 2 for sow preference was performed on several pens (N=14) of sows and gilts with Plastic Mat, Fiber Mat, and Plastic Combs to narrow the preference down to 2 materials to proceed to the farrowing crates. The experiment was carried out in repetitions. Each repetition tested 4 pens at a time. The scratch posts were modified from Exp. 1 and each material was placed in a pen. Due to material destruction only 2 repetitions were carried out, both ending a little early (N=8). During the first repetition (<b>Rep 1</b>), sows ate and destroyed all the Plastic Combs within 2 d. The Plastic Comb scratch posts were pulled from the study and the second repetition (<b>Rep 2</b>) only had the Plastic Mat and Fiber Mat represented. An observation was made that one of the pens in Rep1 had extra feed on their floor and were not destroying their materials as fast as the other pens. So for Rep 2, more modifications to the scratch posts were made and the sows were given a little extra feed. The scratch posts were still destroyed in Rep 2 proving that the sows’ hunger and motivation to perform oral manipulations overwhelmed scratching behaviors. However, from the data that was collected sows spent more time and more frequently interacted with the Fiber Mat compared to the Plastic Mat. They more frequently and spent more time interacting than scratching with the enrichments but scratched on both enrichments the same amount of time and frequency (Durations: F_1,112.6= 13.63, <i>P</i> = 0.0003; Frequencies: F_1,111.9= 19.72, <i>P</i> < 0.0001).</p> <p> The plastic and fiber mats were presented to sows in farrowing crates for the second project by default. Sows (N=18) of parities 2 (<b>P2</b>) and 3 (<b>P3</b>) were housed for 25 d and assigned no enrichment (<b>Control</b>) or to a scratch pad treatment of plastic mats (<b>Plastic</b>) or fiber mats (<b>Fiber</b>). All were assessed for lesions, abnormal behaviors, eating and scratching behaviors, and time spent in different postures and behaviors. Scratching bouts occurred in short durations and were intermittent throughout the day. Parity 2 Plastic sows scratched for a longer total duration than P2 and P3 Fiber sows, P3 Plastic sows, and P2 Control sows (F_2,11= 11.94,<i> P</i> = 0.002). Parity 2 Plastic sows also displayed scratching bouts more frequently than all except P3 Control sows (F_2,11= 18.46, <i>P</i> = 0.0003). There were no body lesion differences between treatments (<i>P</i> > 0.05). Abnormal behaviors (<i>P</i> > 0.05) and proportion of time spent in different postures (F_2,94= 0.0003, <i>P</i> = 0.999) did not differ among treatments. </p> In conclusion, if a sow is experiencing hunger while in gestation pens this motivation may be overwhelming any other behavior needs. Scratch posts were destroyed and eaten. In this sort of environment, focusing on an enrichment that meets the need to forage and root would be more successful. Sows still scratched on the posts, so their preference and scratching use was still recorded to an extent to proceed to the experiment in farrowing crates. In farrowing crates, plastic scratch pads may be a suitable enrichment as they increased the natural behavior of scratching and did not increase abnormal behaviors. More research is needed to refine the scratch pad design and identify additional measures needed to examine the suitability of scratch pads as a form of environmental enrichment for sows in farrowing crates. In addition, the behavioral characteristics and sows’ underlying motivation for scratching need to be studied because very little is known about scratching behavior of sows. If sows are motivated to scratch, and scratching helps improve their welfare, then scratching enrichment may be beneficial to sows and farmers.

Master of Science / Department of Agronomy / Gary M. Pierzynski / Soil chemical and physical properties beneath cattle feedlot pens are largely unstudied. This project was conducted to survey select soil chemical and physical properties of soil beneath active open air cattle feedlots. At four cattle feedlots in Kansas, the concentrations of NH4-N, organic-N, organic-C, Cl-, and P were high at the surface and rapidly decreased within 1.00 m. At three of the four feedlots, NO3-N was generally below background concentration (4.1 mg kg-1) while one feedlot had a >75 mg kg-1 increase in the top 1.00 m. Based on feeding data, only a small percent (7.9 to 1.2) of the total N deposited on the surface was found in the top 1.00 m below the pen surface for a range of 25 to 60 years of operation. While in use, these feedlots do not appear to have a high potential for groundwater pollution from NO3-N leaching. However, if they were to become inactive they may pose a severe threat to groundwater quality from organic-N mineralization and NH4-N nitrification. If feedlots were closed and the land could be largely remediated by removing a layer of soil, these feedlots would have an average 48% profile N removed in a 0.25 m thick layer. A chamber, a modified vacuum desiccator, was tested for the investigation of NH3 volatilization from soil in the laboratory. Ammonia volatilization at the soil surface is dependent on air flow, soil and air temperatures, soil water content, pH, the concentrations of NH3 and NH4+ in the air and soil solution, and factors affecting soil temperature including humidity. This chamber was built to control and/or quantify as many of these variables as possible. A technique for quantifying and predicting NH3 volatilization is important because AFOs are one of the largest contributors of NH3 to the atmosphere, which can cause acid precipitation and particulate matter deposition downwind from the operation. The chambers created allowed for repeated measurements with little error and appear to be a feasible, inexpensive apparatus to investigate NH3 volatilization mechanisms. Using synthetic urine as an N source, NH3 volatilization was affected by initial soil moisture content and soil texture and may be affected by initial soil pH. This chamber has promise to provide excellent data to assist the efforts being made to understand and model NH3 volatilization from feedlot pens.

Electric muscle stimulation (EMS) has been widely used in the rehabilitation of musculoskeletal injuries. Patterned electrical neuromuscular stimulation (PENS), a specific form of EMS, has been developed to better educate muscles to contract properly. The physiological efficacy of PENS has not been quantifiably identified. OBJECTIVES: The aim of this study is to determine the acute effect of one PENS training session (3 sets of 10 1-sec repetitions) on maximal isometric knee extensor (MVIC) torque production and surface EMG (sEMG) in healthy nonathlete college students. DESIGN: A randomized repeated-measures design was used in this study. METHODS: Twenty-two male college students participated in the study. All participants completed two training sessions, one with PENS and one without, in a randomized crossover design. RESULTS: One bout of PENS training significantly increased MVIC (3.1% ± 1.7%, p = 0.03) which was greater than the change in MVIC of the control group (p = 0.03). Control training did not alter MVIC but resulted in significant decrease in average sEMG amplitude (-7.8% ± 1.6%, p ≤ 0.01) and peak sEMG amplitude (-10.4% ± 2.7%, p ≤ 0.01). These reductions in sEMG following control training were significantly different from the PENS group (p = 0.03 and p ≤ 0.01). CONCLUSIONS: The findings suggest that strength training in conjunction with PENS can enhance torque production after just one bout of training. The increase in torque with no change in sEMG amplitude can be explained by increased motor unit synchronization or decreased cocontraction of antagonist muscles.

As principais propriedades físico-químicas da quitosana dependem da massa molar média, grau médio de acetilação (<span style=\"text-decoration: overline\">GA) e do parâmetro de acetilação (PA) que expressa o padrão de distribuição das unidades 2-acetamido-2-desoxi-D-glucopiranose (GlcNAc) e 2-amino-2-desoxi-D-glucopiranose ( GlcN) ao longo de suas cadeias. A distribuição alternada, randômica ou em blocos das unidades GlcN e GlcNAc ao longo das cadeias poliméricas está diretamente relacionada com as condições de preparação da quitosana, sendo que as reações executadas em condições homogêneas geram quitosanas em cujas cadeias há o predomínio da distribuição randômica, enquanto que nas quitosanas produzidas em condições heterogêneas a distribuição em blocos predomina. Neste trabalho &beta;-quitina extraída de gládios de lulas (Loligo sp) foi submetida a 3 etapas consecutivas do processo de desacetilação assistida por irradiação de ultrassom de alta intensidade (processo DAIUS), resultando em quitosana extensivamente desacetilada (<span style=\"text-decoration: overline\">GA &asymp; 2%) e de elevada massa molar média viscosimétrica (<span style=\"text-decoration: overline\">Mv &asymp; 354000 g/mol) comparada a quitosanas obtidas por outros métodos. Essa amostra, denominada amostra QSo, foi dissolvida em ácido acético aquoso e então submetida à reação de N-acetilação por 24 h à temperatura ambiente. A ocorrência de O-acetilação foi evitada pela adição de 1,2-propanodiol ao meio reacional e a variação da razão molar anidrido acético/grupos amino permitiu a obtenção de cinco amostras de quitosanas N-acetiladas, as quais foram caracterizadas por espectroscopia de RMN 1H, espectroscopia na região do infravermelho, difração de raios X, viscosimetria capilar, microscopia eletrônica de varredura e análise termogravimétrica. O parâmetro de acetilação (PA) das quitosanas N-acetiladas foi determinado a partir dos espectros de RMN 1H de modo a permitir a avaliação do tipo de distribuição de unidades 2-acetamido-2-desoxi-D-glucopiranose (GlcNAc) e 2-amino-2-desoxi-D-glucopiranose (GlcN) predominante nos produtos. As reações de N-acetilação foram executadas em duplicata gerando as amostras dos conjuntos 1 e 2, as quais apresentaram <span style=\"text-decoration: overline\">GA variando no intervalo 25%&lt; <span style=\"text-decoration: overline\">GA &lt;55%, sendo constatada variação linear de <span style=\"text-decoration: overline\">GA com a razão molar anidrido acético/grupos amino. As quitosanas N-acetiladas apresentaram parâmetro de acetilação variando com 0,9&lt;PA&lt;1,5, indicando o predomínio da distribuição randômica das unidades GlcNAc e GlcN. As quitosanas N-acetiladas apresentaram maior estabilidade térmica em comparação com a quitosana de partida (amostra QSo), devido a porcentagem de unidades GlcNAc nas cadeias dos polímeros que provocaram alterações na sua estrutura cristalina. Os ângulos de Bragg característicos de &beta;-quitina (amostra QTo) extraída de gládios de lulas foram identificados nos difratogramas das quitosanas N-acetiladas com 30%&lt; <span style=\"text-decoration: overline\">GA &lt;55%, o que sugere que essas amostras adquiriram características semelhantes a da &beta;-quitina. Outra evidência desse fato foi comprovada através da análise das micrografias das amostras de quitosana N-acetiladas, que revelaram que as características das superfícies das partículas das amostras mais acetiladas são semelhantes a da &beta;-quitina. / The main physichochemical properties of chitosan rely on its average molar mass, average degree of acetylation (<span style=\"text-decoration: overline\">GA) and the parameter of acetylation (PA), which expresses the distribution pattern of 2-deoxy-2-acetamido-D-glucopyranose (GlcNAc) and 2-deoxy-2-amino-D-glucopyranose (GlcN) units along its chains. The occurrence of alternated, random or block-like distribution of GlcN and GlcNAc along the polymer chains is directly related to preparation conditions of chitosan. When homogeneous conditions are applied chitosan chains exhibiting random distribution are produced, while the chitosan generated from heterogeneous reactions presents block-like distribution. In this work, &beta;-chitin extracted from squid pens (Loligo sp.) was submitted to three consecutive steps of ultrasound-assisted deacetylation process (USAD process), resulting in an extensively deactylated chitosan (DA=2%) with high viscosity average molar mass (<span style=\"text-decoration: overline\">Mv= 354,000 g/mol) compared to chitosan obtained by other methods. This chitosan, named sample CSo, was dissolved in aqueous acetic acid and then it was submitted to N-acetylation reaction for 24 hours at room temperature. The occurrence of O-acetylation was prevented by adding 1,2-propanediol to the reaction nedium and the variation of the molar ratio acetic anhydride/amino groups allowed the preparation of five N-acetylated chitosans, named as samples RCSon, which were characterized by 1H NMR spectroscopy, infrared spectroscopy, X-ray diffraction, viscometry, scanning electron microscopy and thermogravimetric analysis. The parameter of acetylation (PA) of N-acetylated chitosans was determined from the 1H NMR spectra, allowing the assessment to the distribution pattern of GlcNAc and GlcN units. The N-acetylation reactions were carried out in duplicate, generating two independent sets of N-acetylated chitosans whose average degree of acetylation ranged as 25% &lt; DA &lt; 55%, a linear increase of DA with increasing molar ratio acetic anhydride/amino groups being observed. The N-acetylated chitosans presented parameter of acetylation ranging as 0,9 &lt; PA &lt; 1,5, indicating the predominance of random distribution of GlcNAc and GlcN units. The N-acetylated chitosans showed higher thermal stability as compared to the parent chitosan (CSo sample), probably due to the changes in the degree of order resulting from the higher content of GlcNAc units present in former samples. The Bragg angles characteristic of beta-chitin (CTo sample) were identified in the XRD patterns of N-acetylated chitosans, suggesting that these samples acquired similar characteristics as beta-chitin. Further evidence of this fact was observed through the SEM analyses, which revealed that the characteristics of particle\'s surfaces of N-acetylated chitosans are similar to those of beta-chitin.