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A new poultry litter disinfection methodology against pathogenic Salmonella spp. serovars using gaseous ammonia is proposed in this study. In the laboratory, the poultry litter was disposed into plastic containers and experimentally contaminated with 3 Salmonella spp. serovars separately. Positive and negative control groups were tested. With a system of hoses, 1% gaseous ammonia was injected into the containers in cycles for 48 h. Samples of the poultry litter were collected and submitted to bacteriological analysis. For the second part, we selected a broiler poultry farm with positive litters for Salmonella heidelberg in 2 houses. The littler was treated by gaseous ammonia in a concentration of 2,411 ppm and wrapped with a plastic cover for 48 h during the sanitary break. After the treatment, a new broiler batch was housedand swab samples were collected in the 25-day-old. After the action of the gaseous compound, there was no reisolation of the serovars, and the batches housed on the ammonia-treated litter no longer showed positive results for Salmonella . The total elimination of the pathogenic microorganisms by the new method suggests that the controlled use of ammonia gas in poultry litter may represent a viable disinfection technique.

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The current techniques used in the disinfection of reused poultry litter, such as lime addition, windrowing and plastic cover on the surface, do not guarantee the elimination of pathogenic microorganisms, causing damage to the environment and animal health. Gram negative bacteria, i.e., Salmonella and Escherichia coli, can be transmitted from one batch to another through reused litter, causing health damage to broilers and humans that consume food contaminated by these agents. Our study assessed the effectiveness of the methods plastic cover on the surface (PCS) and plastic cover on the surface with ammonia gas injection (PCSAI) in the control of Gram negative bacteria. The results obtained, both in laboratory conditions (Experiment 1) and in the field (Experiment 2), demonstrate that the method PCSAI with 0.22% ammonia gas had a significant reduction (P<0.05) of Gram negative bacteria in the period of 48 hours This new methodology for disinfecting poultry litter will allow its reuse in a practical and safe way, improving the preservation of the environment, of the health of broilers and consumers of poultry products.

RESUMOO aço inoxidável superasutenítico apresenta diversas aplicações tecnológicas, principalmente em ambientes corrosivos. A precipitação de diferentes fases pode alterar algumas de suas propriedades mecânicas. Tais alterações afetam vários fatores, incluindo a vida útil do material diante de condições de trabalho adversas. Neste estudo, medidas de Indentação Instrumentada, Tribologia e Difração de Raios X (DRX) foram utilizadas para avaliar possíveis alterações em regiões próximas à superfície em amostras tratadas termicamente. Os parâmetros analisados foram: dureza e módulo de elasticidade, coeficiente de atrito e alterações estruturais na célula unitária nas fases identificadas. Os resultados foram comparados com aço austenítico comum da famí-lia AISI 304. A presença das fases  (grupo espacial P42mnm) e austenita- (grupo espacial Fm3m) foram detectadas. Os dados analisados indicaram que a presença da fase intermetálica  contribuiu para pequenas alterações na dureza em regiões próximas à superfície e no coeficiente de atrito. Para regiões mais profundas (bulk) as propriedades analisadas foram semelhantes aos aços inoxidáveis comerciais.Palavras-chave: aço austenítico, aço superaustenitico, refinamento Rietveld. ABSTRACTThe superaustenitic stainless steel presents several technological applications, mainly in corrosive environments. The different phase precipitation might alter some of its mechanical properties. Such alterations affect several factors, including the working life of the material under adverse working conditions. In this study, Instrumented Indentation techniques, Tribology and X-ray diffraction (XRD) were used to evaluate alterations in regions close to the surface. The parameters analyzed were: hardness and elastic modulus (instrumented indentation), friction coefficient (tribology) and structural alterations of the unit cell of the identified phases (XRD -Rietveld Refinement). All properties analyzed were compared with those of common austenitic steel. The presence of -phase (space group P42mnm) and -austenite (space group Fm3m) were detected. Data analyzed indicated that the presence of -phase caused small alteration in properties such as hardness in regions close to the surface. In the regions farther from the surface (material bulk) data can be compared to that of conventional austenitic steel.

Adequate mechanical responses are decisive features for novel superconductor materials, ideally enabling their machinability and conformability capacities to produce practical devices. The recently developed polycrystalline Bi4O4S3 superconductor was prepared following a two-step solid state reaction. Grains consisted of lamellae, ∼5 μm in the planar orientation and 100–500 nm thick, presenting a tetragonal crystalline structure. The mechanical and tribological properties of the millimeter-size samples were investigated at the nanoscale using varied testing routines. Indentation hardness was about 1.6 GPa, whereas elastic modulus was 50–53 GPa. At the nanometer scale, cracks were visible through all the surface, possibly due to the structural inherent features of the material. On the other hand, it disclosed ductile-like plastic deformation features under normal loading and scratch tests up to 100 mN, as predicted by the index of plasticity H/E* ≈ 0.3. In these tests, the BiS2-based material presented some limited strain hardening, but with the absence of load-induced fractures.

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