The use of fission product yield data is pervasive among nuclear calculations, particularly in the realm of nuclear forensics and active interrogation for special nuclear material. The capital source of fission product yield data is the work of T.R. England and B.F. Rider, of Los Alamos National Laboratory, in the early 1990s. Though their work was certainly substantial, a great deal of data was generated computationally, in lieu of done empirically—particularly with low-yield, short-lived progeny. Due to this, relative uncertainties in the measurements can be as high as 64%, and vary wildly from database to database (oft times not even within one standard deviation of one another). The purpose of this work is to build a pneumatic system capable of cyclic irradiation coupled to a D-T neutron source, in order to cumulate proper counting statistics, by which one can backcalculate independent and cumulative fission yields. Beyond the design and control parameters of the pneumatic system, a precise flux characterization of the facility is presented, and finally, proof-of-concept is demonstrated by causing 14 MeV neutron-induced fission and identifying every observed fission product photopeak. / text

The rostral ventrolateral medulla (RVLM) is the origin of a ¡§life-and-death¡¨ signal identifies from systemic arterial blood pressure spectrum that reflects failure of central cardiovascular regulation during brain stem death. It is also a target site where endogenous angiotensin II acts on angiotensin II type 1 receptors (AT1R) to increase blood pressure (BP); or on type 2 receptors (AT2R) to inhibit baroreceptor reflex (BRR) response. This study investigated the roles of AT1R and AT2R and their signaling pathways in RVLM for ¡§life-and-death¡¨ signal response during experimental brain stem death, using organophosphate mevinphos (Mev) as the experimental insult. In Sprague-Dawley rats, Mev (640 £gg/kg, i.v.) elicited an increase (pro-life phase) followed by a decrease (pro-death phase). Real-time PCR analysis revealed that whereas AT1R level underwent a 10% increase at pro-life phase, AT2R exhibited a significance increase of up to 40% at pro-death phase. Western blot analysis revealed that whereas AT1R level underwent a 20% increase at pro-life phase, AT2R exhibited a significant increase of up to 50% at pro-death phase. Pretreatment with microinjection of an AT1R antagonist losartan (2 nmol) into RVLM elicited abrupt death because of drastic hypotension through inhibiting NADPH oxidase and its downstream superoxide anion. Pretreatment with NADPH oxidase inhibitor DPI (1.5 nmol) inhibited NADPH oxidase avtiviting and superoxide anion production and decreased ¡§life-and-death¡¨ signal at pro-life phase; using superoxide anion inhibitor tempol (5 nmol) potentiated blood pressure and ¡§life-and-death¡¨ signal at pro-death phase. However, pretreatment with an AT2R antagonist PD123319 (2 nmol) potentiated the ¡§life-and-death¡¨ signal and antagonized hypotension during pro-death phase through inhibiting protein phosphotase 2A (PP2A) then activating extracellular signal-regulated kinase 1/2 (ERK1/2). Similar to AT2R antagonist PD123319, pretreatment with PP2A inhibitor okadaic acid (0.5 fmol) inhibit PP2A, leading to activation of ERK1/2, potentiate ¡§life-and-death¡¨ signal and antagonized hypotension during pro-death phase. These results suggest that AT1R in RVLM plays a ¡§pro-life¡¨ role through NADPH oxidase/superoxide anion during experimental brain stem death by maintaining BP and ¡§life-and-death¡¨ signal; AT2R plays a ¡§pro-death¡¨ role through PP2A/ERK1/2 by inhibiting BP and ¡§life-and-death¡¨ signal, and superoxide may also plays a ¡§pro-life and pro-death¡¨ role at pro-death phase.

Made available in DSpace on 2016-08-29T15:36:46Z (GMT). No. of bitstreams: 1 tese_7403_Resumo Dissertação Final - Olívia Furlan Cavallini -PDF.pdf: 51251 bytes, checksum: 9b0f8ad28b2392e17f576316563af6c1 (MD5) Previous issue date: 2015-02-24 / A fruta-pão é um fruto rico em vitaminas e minerais do qual pode ser extraído o amido ou processado à forma de farinha aumentando sua vida de prateleira. Essa farinha pode substituir parcialmente a farinha de trigo em produtos panificáveis. O objetivo do presente estudo foi extrair e analisar algumas características físicas, químicas e tecnológicas do amido nativo de fruta-pão, além de realizar a caracterização físico-química da farinha obtida desse fruto, de suas misturas com a farinha de trigo e verificar a viabilidade destas na elaboração de pão de forma. O amido de fruta-pão foi submetido às análises de umidade, capacidade de ligação de água a frio (CLAF), poder de inchamento (PI), índice de solubilidade (IS), sinérese, microscopia eletrônica de varredura (MEV) e difração de raio X. O amido de milho foi analisado para efeito de comparação. O amido de fruta-pão apresentou maior umidade (18,32%), CLAF (80,33%), PI (198,71 g/g a 90 0C), IS (7,22% a 90 0C) e sinérese (2,69 mL) quando comparado com o amido de milho. Pela análise de MEV, verificou-se que o amido de fruta-pão apresentou grânulos menores que os do amido de milho, mas ambos com formato poliédrico. A difração de raio X permitiu classificar o amido de milho como tipo A e o de fruta-pão como tipo B. As amostras de farinha analisadas continham um percentual de farinha de fruta-pão de 0% (controle), 5%, 10%, 15%, 20% e 100% e foram submetidas às análises de umidade, cinzas, extrato etéreo, carboidratos, proteína, energia, fibra total, solúvel e insolúvel, pH, cor e granulometria. Os mesmos percentuais de substituição foram utilizados para a elaboração dos pães, analisados em relação a umidade, peso, volume, volume específico, altura, perfil de textura, aceitação sensorial e intenção de compra. A substituição da farinha de trigo pela farinha de fruta-pão influenciou na granulometria das misturas, reduziu o teor de proteína de 10,8% para 3,99%, elevou o percentual de carboidratos, cinzas e pH de 73,84%, 0,52% e 5,94 para 83,10%, 2,19% e 6,34 , respectivamente. No entanto, para a umidade, teor de lipídeos e diferença global de cor das amostras não foi verificada influência significativa do percentual de substituição. A farinha de fruta-pão apresentou um maior percentual de fibras totais (21,17%), solúveis (10,39%) e insolúveis (10,77%). Para os pães de forma, o aumento da substituição não influenciou na umidade e no peso dos pães, exceto para a amostra com 100% de farinha de fruta-pão, que apresentou 41,28% de umidade e peso de 588,65 g. Para as demais análises, os maiores percentuais de substituição influenciaram negativamente as características do produto. Em relação a caracterização físico-química das amostras de farinha, o aumento do percentual de substituição influenciou na maioria dos parâmetros avaliados. Para os pães, as formulações com maiores notas hedônicas e com melhor intenção de compra foram as com substituição de 5% e de 10%.

Made available in DSpace on 2018-08-01T21:58:45Z (GMT). No. of bitstreams: 1 tese_10255_Rayana Alvarenga Costa.pdf: 3195656 bytes, checksum: 244f9112e799add76c1a8840cbe40dce (MD5) Previous issue date: 2016-09-29 / Tendo em vista a forte relação entre os crimes de homicídio e o uso de armas de fogo no Brasil, a Balística Forense tem como importante ferramenta a detecção de resíduos originados por disparo de armas de fogo (GSR - GunShot Residues) nas mãos de um suspeito, contribuindo para determinação da autoria de um disparo. Dentre os tipos de munições existentes, a munição limpa foi desenvolvida na última década para minimizar a exposição dos atiradores ao chumbo (Pb), visto que em munições convencionais este elemento, bem como o Ba e Sb se apresentam em concentrações significativas. Estudos mostram dificuldades na detecção de GSR de munição limpa por espectroscopia de energia dispersiva acoplado a microscopia eletrônica de varredura (MEV/EDS) e teste residuográfico. Técnicas analíticas modernas como a espectrometria de massas com plasma indutivamente acoplado (ICP-MS) vem sendo utilizada como uma análise rápida para a detecção de elementos químicos presentes nos GSR, por apresentar alta sensibilidade, seletividade e caráter multielementar. Desta forma, o objetivo deste trabalho foi avaliar a aplicabilidade da técnica da ICP-MS para quantificar os GSR advindos de munições limpas ou clean range ammunition ou non toxic ammunition utilizando pistola calibre .40 e revólver calibre .38 em função do número de disparos (n = 1-7 e n = 1-5, respectivamente). Os GSR foram coletados nas regiões da pinça-palmar e pinça-dorsal, sendo avaliadas sobre ambas as mãos (direita e esquerda). Os resultados obtidos foram comparados com técnicas clássicas dentro da balística forense: ensaio colorimétrico usando rodizonato de sódio e MEV/EDS. Resultados negativos foram observados para Pb e Ba usando o teste residuográfico para análise de GSR de munições limpas, até 7 disparos. Já a análise por MEV/EDS foi realizada no GSR produzido a partir de n = 7 (pistola calibre .40) e n = 5 (revólver .38) de munição limpa. As fotomicrográficas mostraram que o GSR produzido a partir da munição limpa não apresenta morfologia definida como os do GSR de munição convencional. Além disso, os resultados de EDS identificaram principalmente elementos como C, O, K, Al, S, Si, Cu, Zn, Ti, Cr, Cl, Mo, Sr e Fe. Diferente dos métodos convencionais, a técnica de ICP-MS mostrou resultado positivo para Pb, Ba e Sb com concentração máxima de 2,64 (±0,60) μg∙L-1, 10,9 (±5,44) μg∙L-1 e 0,12 (±0,02) μg∙L-1 para pistola .40 e 4,59 (±1,8) μg∙L-1, 1,95 (±1,1) μg∙L-1, 0,10 (±0,07) μg∙L-1 para revólver .38. Além deles, elementos como Al, Ti, Cr, Mo, Cu, Zn e Sr foram também detectados nos GSR de munições limpas. Observou-se que com o aumento do número de disparos houve o aumento da concentração de todos os elementos investigados e sugere-se que Al, Sr, Zn e Cu possam vir a ser utilizados como novos marcadores de GSR para munições limpas. Portanto, a técnica ICP-MS apresentou resultados promissores e mostrou-se adequada para a análise de GSR de munições limpas

The purpose of this paper is to study the possible excited states in the nucleus of Cs133. At North Texas State College a 100-Kev Cockcroft-Walton accelerator has been constructed for use as a neutron source for exciting various nuclei and for studying the gamma spectra obtained to determine their energy levels.

Introduction All experimental studies involving charged particle induced nuclear reactions require a precise knowledge of monitor reactions. A number of well described proton induced monitor reactions exist in the lower energy range [1], which is covered by most medical cyclotrons. Concerning proton energies above 20 MeV, however, the accuracy of the monitor reactions declines as cross section data becomes scarcer. Furthermore, the growing interest in precise determination of projectile energies by comparing of ratios of monitor reaction cross sections demands new measurements and evaluations of known data for high threshold monitor radionuclides. In this work cross section measurements on the formation of 61Cu were done and energy de-pendent radionuclide ratios were calculated. Material and Methods For investigation of the natCu(p,x)61Cu reaction copper foils of natural isotopic composition (Goodfellow Ltd.) were irradiated. The targets were of 10 and 20 μm thickness, having a diameter of 15 mm. Proton bombardments up to 45 MeV incident energy were done in the stacked-foil arrangement at the accelerator JULIC of the Nuclear Physics Institute (IKP) of the Forschungszentrum Jülich. In addition to an internal irradiation possibility the cyclotron is equipped with an external target station which was used for most experiments. It can adapt standard and slanting solid target holders and is equipped with a water cooled four sector collimator and additional helium cooling of the entry foil. Several irradiations were executed. In each stack, besides copper samples, aluminium absorbers and additional nickel monitor foils were also placed, the latter for the determination of the respective beam current. The produced radioactivity of 61Cu was analysed non-destructively using HPGe γ-ray detectors (EG&G Ortec). Results and Conclusion Reaction cross sections of the natCu(p,x)61Cu process up to 45 MeV were measured and com-pared with existing data from the literature (FIG. 2). Except for the data of Williams et al. our results are in good agreement, showing a maxi-mum of about 165 mbarn at 37.5 MeV proton energy. The overall uncertainty of the new cross section data is between 8 and 10 %. In FIG. 3, the excitation functions of the relevant monitor reactions on Cu are shown. In combination with the excitation function of the natCu(p,xn)62Zn reaction, isotope ratios were calculated which can be used for determination of the proton energy within a target stack in the energy range of 22–40 MeV as described by Piel et al. [3]. FIGURE 4 shows the cross section ratio in dependence of the proton energy. Above this energy, 65Zn could be used to generate isotope ratios for energy determination, although the long half-life (T½ = 244.3 d) of that radionuclide may be a problem. Additional cross section measurements are planned in order to further strengthen the data base of this potential monitor reaction. The results of this work shall be evaluated in the framework of an ongoing Coordinated Research Project of the IAEA.

Introduction The worldwide use of PET has proven beyond dispute the importance for both routine diagnosis and physiological, oncological and pharmacological research. In many ways the present success of PET relies on the mature technology of PET compact medical cyclotrons. As long time developers of new targets, isotopes and com-pounds, we have been inclined to look for new block-buster applications, high power targets and sustainable ways of embracing the GMP and regional distribution, but recent pioneering development [1] around very small cyclotrons and “embedded synthesis and qc” has pointed out an old, but important nuclear physics lesson now halfway forgotten: that many PET isotopes can be made in high yields with proton energies far below 10 MeV [2]. This has opened a new interest in small cyclotrons and their targets. We have been testing the first GE Healthcare Prototype for a 7.8 MeV negative ion, internal ion source cyclotron with 3 production targets mounted on a short beamline. Here we present the first experimental yields of some of the important PET radionuclides. Materials and methods The prototype cyclotron (FIG. 1) has been in-stalled and tested without self-shield in designated experimental area in order to establish the neutron field around accelerator and targets in order to qualify design calculations for a future integrated shield. The cyclotron energy is fixed by the radial position of the extraction foil, while the azimuth determines which of the 3 targets are being irradiated. The beam energy at front of target foil was determined on several occasions: 7.8 ± 0.1 MeV by a 2 copper-foil sandwich method (adopted from [3]). The available beam inside the cyclotron at extractor position is > 50 μA, and 35 μA are easily and long term reliably extracted (> 90 %) on to any of the 3 target positions. The prototype is capable of delivering more than 40 μA to target, but target current was limited to 35 μA under present unshielded conditions. Results 18F We have tested the prototype gridded (> 80 % transmission) niobium body target with 10μm Havar foil using 95 % 18O water and 35 μA on target + grid with yields given in TABLE 1. The observed yields corrected for stopping in foil, grid loss and water enrichment are 75 % of theoretical. One Fastlab FDG run using 2 h irradiation yielded 16 GBq FDG EOS, confirming the “usual” 18F activity. Results 11C Using gridded target and a 10μm foil with 99% N2 + 1 % O2 at 10 bar followed by trapping into ascarite gave EOB activity as shown in TABLE 2. Results 13N We know that the 16O(p,alpha)13N cross section is a very steep function of energy around 7.8 MeV. In the hope of using the simple water target route to 13N NH3 we have measured the 13N yields (corrected for 18F contribution). It is still unclear if these yields can be improved to make useful single doses of ammonia. Results for other isotopes We have used solid targets to make 45Ti, 64Cu, 68Ga and 89Zr. The development of these solid targets is still in progress, but especially the 68Ga yield looks promising (3 GBq EOB after 1 h on natural Zn will give > 15 GBq on enriched 68Zn).

Introduction A method based on neutron activation is being developed to assist in resolving discrepancies between the expected yield and actual yield of radionuclides produced with the vertical-beam target station (VBTS) at iThemba LABS. The VBTS is routinely employed for multi-Ci batch productions of the radionuclide pairs 22Na/68Ga and 82Sr/68Ga using standardized natMg/natGa and natRb/natGa tandem targets, respectively [1]. The metal-clad target discs are bombarded with a primary beam of 66 MeV protons at an intensity of nominally 250 µA. The encapsulation materials are either Nb (for Mg and Ga) or stainless steel (for Rb) which serve to contain the molten target materials during bombardment and act as a barrier to the high-velocity cooling water which surrounds the targets in a 4π geometry. The natRb/natGa targets are typically bombarded according to a two-week cycle while natMg/natGa targets are bombarded on an ad-hoc basis, depending on a somewhat unpredictable 22Na demand. A too-large deviation between expected yield and actual yield has at times plagued this programme. These deviations can manifest both as an apparent loss or an apparent gain (relative to the expected yield) by up to about 15% in either direction. The resulting uncertainty of up to 30% (in the worst case) from one production batch to another can be costly and is unacceptable in a large-scale production regimen. This phenomenon is believed to be brought about by two types of problems: (1) Production losses, e.g. during the radio-chemical separation process or incomplete recovery of activated target material during the decapsulation step. (2) Incorrect values obtained for the accumulated proton charge. A problem of type (1) will always result in a loss of yield. A problem of type (2) can manifest as an apparent loss or gain. In an effort to get a handle on this second type of problem, neutron activation of suitable material samples, embedded in a target holder, is being investigated as an independent indicator of the total yield. For this purpose, samples of Co, Mn, Ni and Zn were activated during production runs and Co was found to be the most appropriate. Preliminary results will be presented after first discussing why the determination of the accumulated pro-ton charge is a problem with the VBTS. Materials and Methods The VBTS consists of a central region in which a target holder is located during bombardment as well as two half-cylindrical radiation shields which completely surround the target. The shields can be moved away from the central region on dedicated rails, e.g. when repairs or maintenance is required. FIGURE 1 shows the VBTS with the shields moved to the “open” position. As some components of the station are located below the vault floor, with the target position near floor level, it proved difficult to electrically isolate the VBTS as was done for the two horizontal-beam target stations at iThemba LABS [1]. The VBTS does not act as a Faraday cup like the other target stations. Instead, the beam current and accumulated charge is measured by means of a calibrated capacitive probe [1,2]. There appears to be a variation in the response of the capacitive probe, sensitive to the beam microstructure, in particular a dependence on the beam packet length. This problem is not yet fully resolved. FIGURE 2 (a) shows the beamstop of a VBTS target holder with several Co samples mounted on the outside as well as one each of Ni, Mn and Zn. The samples are small “tablets” with a 10 mm diameter and 1 mm thickness. The reactions of interest are 59Co(n,γ)60Co, 59Co(n,3n)57Co, nat-Ni(n,X)60Co, natNi(n,X)57Co, natZn(n,X)65Zn and 55Mn(n,2n)54Mn. The relevant half-lives are 60Co(5.271 a), 57Co(271.8 d), 65Zn(244.3 d) and 54Mn(312.2 d). The half-life should be long compared to the two-week cycle in order to reduce the dependence on the exact beam history, which is very fragmented over any production period. In this respect, 60Co is considered to be particularly attractive as its long half-life of more than 5 years leads to a negligible effect by the beam history. Note that the tandem targets, shown in FIGURE 2 (b), are mounted just upstream of the beamstop – in fact, the targets and beamstop form a single unit before being fitted into the target holder. At the end of bombardment, all samples were assayed for their characteristic γ-emissions using standard off-line γ-ray spectrometry with an HPGe detector connected to a Genie 2000 MCA. Calculations of the neutron fluence density in the central sample volume on the beamstop were also performed using the Monte Carlo radiation transport code MCNPX. For these calculations, the entire VBTS, a Rb/Ga target and the vault walls were included in the model. Results and Conclusion All samples activated significantly – copious amounts of 60Co were detected in the Co discs after a two-week run. The neutron fluence density for the case of a 250 µA, 66 MeV proton beam on a natRb/natGa tandem target is shown in FIGURE 3. The dominance of low-energy neutrons is evident, which is in part due to the large amount of paraffin-wax shielding material in close proximity to the target. While reactions such as the (n,2n) and (n,3n) would be sensitive to the more energetic part of the neutron spectrum, the (n,γ) capture reaction benefits from the large low-energy component. This explains the copious amounts of 60Co formed. It was therefore decided to only retain the central Co sample for subsequent bombardments, as shown in FIGURE 4. The first results are shown in TABLE 1. The accumulated charge as obtained from the capacitive probe (Q), the specific 60Co activity (A) at the end of bombardment (EOB), and their ratio (A/Q) are presented in the table, together with the deviation of individual ratios relative to their average for the case of the Mg/Ga tandem tar-gets only. Note that all samples were counted until the statistical uncertainties were negligible. Any systematic uncertainties are ignored at this stage as they are considered to remain the same from one batch production to another. For the sake of argument, the average value of the ratio is taken as the expected value. A positive deviation of the A/Q value is then indicative of a too-small value of the accumulated charge obtained from the capacitive probe, leading to a corresponding overproduction. Likewise, a negative value is indicative of a too-large value of the accumulated charge, leading to a corresponding underproduction. It is certainly true that the data in TABLE 1 are currently very limited. It is envisaged, however, that with time the growing database of values will assist in reducing the uncertainty in determining the accumulated charge and reduce the discrepancies between predicted and actual yields significantly. TABLE 1 illuminates the underlying problem satisfactorily. The four Mg/Ga tandem target bombardments, on identical targetry, were performed successively. The neutron activation correlates well the with actual yields, pointing directly to the current integration as the main source of error. The method already proves to be useful. An indication of an over or underprediction can be obtained prior to the target processing by recovering and measuring the Co disc. This in-formation can be used to make a decision concerning the present batch production and/or the subsequent one. One can either add beam to the present production target and/or in-crease/reduce the total beam on the subsequent production target to compensate for an expected overproduction or shortfall. In conclusion, we would like to stress that the capacitive probes show great promise and that better understanding and/or possibly some development of their signal processing algorithm may improve their ability to measure the accumulated charge to the desired accuracy. Segmented capacitive probes used at iThemba LABS and elsewhere for beam position measurement [1,3] are not affected by beam microstructure as only the ratios of the signal strengths on the different sectors are important. In this case, changes in response affect all sec-tors equally and the ratios are unaffected.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / The objective of this research was to obtain powder from the pulp of integral acerola two drying methods (spray-dryer and freeze drying), and the determination of physical and chemical stability and hygroscopic and morphological characteristics. Acerola pulps were acquired in the trade of Fortaleza. The pulp was characterized and post as the physicochemical, colorimetric and morphological parameters. The study of the stability of the powders was carried out in three distinct packaging for a period of 90 days. The adsorption isotherms were also determined. The results indicated optimal conditions for drying spray-dryer using drying temperature of 154 ÂC and the pulp concentration maltodextrin 17,1%, while in the lyophilizer, 19,1% maltodextrin with lyophilization time of 24 hours. All physico-chemical parameters evaluated in the whole pulp undergo change after drying. The drying spray-dryer powder generated with lower humidity, and lyophilization produced a more hygroscopic powder, with a greater degree of caking, and better color preservation, the pH being a parameter of small variation. The study of the stability of acerola pulp powder obtained by different drying methods allowed us to observe increased humidity and coordinate a* b* and decreased ascorbic acid and brightness. The use of laminated packaging laminate vacuum was effective to maintain moisture and hygroscopic powder, with less loss of ascorbic acid for packaging laminda vacuum. The BET model best fit the adsorption isotherms of the lyophilized powder acerola pulp, while for the spray-dryer model Oswin better adjusted to 25 ÂC, and Henderson model for 35 and 45 ÂC. Morphological characterization showed by analysis of Microcopia Scanning Electron (SEM), X-ray diffraction (XRD) spectroscopy and Fourier Transform Infrared (FTIR-ATR) that the lyophilization process generates an amorphous powder and adding maltodextrin protects the frame of samples and permits lower moisture absorption also show similar composition between samples, and a higher absorbance obtained is lyophilized in the whole sample. / O objetivo desta pesquisa foi a obtenÃÃo de pà a partir da polpa de acerola integral por dois mÃtodos de secagem (spray-dryer e liofilizaÃÃo), assim como a determinaÃÃo da estabilidade fÃsico-quÃmica e caracterÃsticas higroscÃpicas e morfolÃgicas. As polpas de acerola foram adquiridas no comÃrcio de Fortaleza-CE. Caracterizou-se a polpa e os pÃs quanto a parÃmetros fÃsico-quÃmicos e colorimÃtricos e morfolÃgicos. O estudo da estabilidade dos pÃs foi realizado em trÃs embalagens distintas por um perÃodo de 90 dias. Determinou-se ainda as isotermas de adsorÃÃo. Os resultados indicaram condiÃÃes Ãtimas de secagem em spray-dryer utilizando temperatura de secagem de 154ÂC e concentraÃÃo de maltodextrina na polpa de 17,1%, enquanto para o liofilizador, 19,1% de maltodextrina com tempo de liofilizaÃÃo de 24 horas. Todos os parÃmetros fÃsico-quÃmicos avaliados na polpa integral sofrem variaÃÃo apÃs secagem. A secagem em spray-dryer gerou pà com menor umidade, e a liofilizaÃÃo gerou um pà mais higroscÃpico, com maior grau de caking, e melhor preservaÃÃo da cor, sendo o pH um parÃmetro de pequena variaÃÃo. O estudo da estabilidade das polpas de acerola em pà obtidas por diferentes mÃtodos de secagem permitiu observar aumento da umidade e das coordenadas a* e b* e diminuiÃÃo do Ãcido ascÃrbico e luminosidade. O uso de embalagens laminada e laminada a vÃcuo mostrou-se eficaz para a manutenÃÃo da umidade e higroscopicidade dos pÃs, com menor perda de Ãcido ascÃrbico para a embalagem laminada a vÃcuo. O modelo de BET melhor se ajustou as isotermas de adsorÃÃo o pà de polpa de acerola liofilizado, enquanto para o spray-dryer o modelo de Oswin melhor se ajustou a 25ÂC, e o modelo de Henderson para 35 e 45ÂC. A caracterizaÃÃo morfolÃgica mostrou pelas anÃlises de Microcopia EletrÃnica de Varredura (MEV), DifraÃÃo de Raios-X (DRX) e Espectroscopia de Infravermelho com Transformada de Fourier (FTIR-ATR) que o processo de liofilizaÃÃo gera um pà amorfo e que a adiÃÃo de maltodextrina protege a estruturadas amostras e permite uma menor absorÃÃo de umidade, ainda mostra composiÃÃo similar entre as amostras, e que uma maior absorbÃncia à obtida em amostra integral liofilizada.

A formação de biofilmes em superfícies que entram em contato com alimentos pode resultar em contaminação em qualquer parte do processo produtivo, podendo assim, ser causa de doenças transmitidas por alimentos. A formação de biofilmes por Staphylococcus ssp. é uma das grandes preocupações na indústria de lácteos, e também na área da medicina veterinária. A presente pesquisa teve como objetivo avaliar a capacidade de formação de biofilmes de Staphylococcus spp. isolados de laticínios produtores de queijo Minas Frescal e de leite de vacas com mastite subclínica. O estudo foi realizado em 3 fases, sendo a primeira uma caracterização fenotípica de 150 isolados de Staphylococcus spp. pelo teste do Ágar Vermelho Congo (AVC). Na segunda fase, foi realizada uma caracterização genotípica dos isolados de Staphylococcus spp., pesquisando os genes icaA, icaD, bap, bbp, cna, ebpS, eno, fib, fnbA, fnbB, clfA e clfB. Na terceira fase foram selecionadas 10 cepas com diferentes perfis genotípicos e três cepas padrão de Staphylococcus spp., para avaliação da capacidade de formação de biofilmes. Foi avaliada a capacidade de formação de biofilmes das 13 cepas em três tempos (12h, 48h e 96h), duas temperaturas (5°C e 25°C) e duas superfícies de contato (aço inoxidável 304 e polipropileno) tendo como primeira variável resposta a densidade óptica a 600 nm obtida utilizando metodologia do cristal violeta e a segunda variável resposta foi a contagem microbiológica de células viáveis (log10UFC cm-2) aderidas nas superfícies testadas. Foi utilizado um Delineamento Inteiramente Casualizado (DIC) com fatorial de 13x3x2x2. No AVC 38,7% (n=58) dos 150 isolados foram positivos para formação de biofilme. Observou-se que 93,3% (n=140) dos 150 isolados possuíam o gene clfA, 87,3% (n=131) o eno, 62,7% (n=94) o ebpS, 54,7% (n=82) o fib, 54% (n=81) o fnbA, 53,3% (n=80) o icaD, 47,3% (n=71) os genes icaA e clfB, 43,3% (n=65) o fnbB, 17,3% (n=26) o bap, 8% (n=8) o cna e 4% (n=40) o gene bbp. Pelo Teste de Friedman (&alpha;=0,05) os fatores cepa, temperatura e superfície foram significativos (p<0,0001) para as duas variáveis resposta na formação de biofilmes, enquanto que, entre os tempos de avaliação não houve diferença significativa (p>0,05). A maior produção de biofilme (avaliada por densidade óptica) foi observada a 25°C no aço inoxidável, sendo que as cepas S. epidermidis ATCC 35984 e S. aureus 119 foram as cepas que apresentaram maior formação de biofilme. Nas superfícies testadas foram observadas contagens microbiológicas na faixa entre 6,5 e 7,6 log10UFC cm-2 que sugerem formação de biofilme. Foram selecionadas 6 cepas para realizar a Microscopia Eletrônica de Varredura (MEV), as quais confirmaram a formação de biofilme em aço inoxidável e polipropileno em 5°C e 25°C sendo avaliadas á 12 e 96 horas. / The biofilm formation on surfaces, which are contact with food, can result in contamination in any part of the food processing, causing foodborne illness. The biofilm formation by Staphylococcus ssp. is one of the main concern in the dairy industry, and in the veterinary medicine field. This research aimed to evaluate the biofilm formation capacity of Staphylococcus spp., isolated from dairy producers of \"Minas Frescal\" cheese and cows with subclinical mastitis. The study was conducted in three stages, being the first a phenotypic characterization of 150 Staphylococcus spp. strains using the Congo Red Agar (AVC) test. In the second stage, the genotypic characterization with the screening of the gens icaA, icaD, bap, bbp, cna, ebpS, eno, fib, fnbA, fnbB, cIfA and clfB was performed. In the third stage, 10 strains with different genotypic profiles and 3 standard strains of Staphylococcus spp. were selected to evaluate the biofilm formation capacity. The biofilm formation capacity of 13 strains at three times (12h, 48h and 96h), two temperatures (5 °C and 25 °C) and two contact surfaces (stainless steel 304 and polypropylene) was evaluated. As a result, the optical density at 600 nm obtained by the methodology of crystal violet and the microbiological count of viable cells (log10UFC cm-2) (adhered to the tested surfaces) was analyzed. A completely randomized design was used in a factorial 13x3x2x2. In AVC agar, 38.7% (n = 58) of the 150 isolates were positive for biofilm formation. The 93.3% (n = 140) of the 150 isolates had the cIfA gene, 87.3% (n = 131) the eno, 62.7% (n = 94) the ebpS, 54.7% ( n = 82) fib, 54% (n = 81) the fnbA, 53.3% (n = 80) the icaD, 47.3% (n = 71) icaA and clfB gens, 43.3% (n = 65) the fnbB, 17.3% (n = 26) bap, 8% (n = 8) the cna and 4% (n = 40) bbp gene. The factors strain, temperature and surface were significant (Friedman test p <0.0001) for both response variables in the formation of biofilms, while, time did not have significant difference (p> 0.05). The increased production of biofilm (assessed by optical density) was observed at 25 °C in stainless steel surfaces. The strains S. epidermidis ATCC 35984 and S. aureus 119 were the strains that showed the highest production of biofilm. In the tested surfaces, microbiological counts were observed in the range between 6.5 and 7.6 log10CFU m-2 suggesting biofilm formation. The formation of biofilms in 6 evaluated strains has been confirmed by Scanning Electron Microscopy (SEM) on stainless steel and polypropylene on 5°C and 25°C with 12 and 96 h of incubation.