Orthogonal cut of SPS-sintered composites with ferrous matrix and Fe Mo S particles: Numerical and experimental analysis

Metal-matrix composites with solid lubricant reinforcements may present a suitable alternative to improve the tribological behavior of sintered components. Besides the performance during the application, the presence of solid lubricants may also modify component manufacture, for example, during machining operations to achieve complex shapes not directly obtained from the sintering process. This work describes a numerical and experimental analysis on the orthogonal cut of metal-matrix composites composed of FeMoS particles embedded in an Astaloy 85 Mo (Höganäes AB) matrix. Specimens were prepared using the Spark-Plasma Sintering (SPS) technique, from mixtures containing powders of Astaloy 85 Mo steel and 2 wt% or 4 wt% of molybdenum disulfide (MoS2). An unreinforced Astaloy 85 Mo specimen (without MoS2) was also included in the analysis. Different microstructures were observed after SPS. The unreinforced specimen presented a ferrite-pearlite structure with a porosity level below 2% and the specimen sintered with 2 wt% of MoS2 presented iron sulfide particles dispersed in the steel matrix. The structure of the specimen sintered with 4 wt % was more complex, with two distinct phases dispersed in the Astaloy 85 Mo matrix. Experimental orthogonal cuts were conducted on the three specimens using a shaper machine tool equipped with a tungsten carbide (WCCo) cutting insert. Tests were recorded using a high-speed camera. The machined surfaces were later analyzed with an optical profilometer and in a scanning electron microscope (SEM) with energy-dispersive X-ray spectroscopy (EDS). The chips were also characterized. The cutting operation was simulated by two-dimensional (2D) finite-element analysis. The meshes were prepared based on the specimen microstructures and considering the properties of the individual phases. Results have indicated significant differences in the cutting process. Observation of the chip surfaces indicates plastic deformation on the unreinforced specimen, in opposition to more uniform scratches on the composite surfaces, especially that of the specimen sintered with 4 wt % of MoS2

Chemical carcinogenesis by 7,12-dimethylbenzanthracene in balb/c mice

FAPES

Comparative genomic survey of Bacillus cereus sensu stricto isolates from the dairy production chain in Brazil

Made available in DSpace on 2018-11-26T17:48:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-02-01Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)The genomes of 262 Bacillus cereus isolates were analyzed including 69 isolates sampled from equipment, raw milk and dairy products from Brazil. The population structure of isolates showed strains belonging to known phylogenetic groups II, III, IV, V and VI. Almost all the isolates obtained from dairy products belonged to group III. Investigation of specific alleles revealed high numbers of isolates carrying toxin-associated genes including cytK (53.62%), hblA (59.42%), hblC (44.93%), hblD ( 53.62%), nheA (84.06%), nheB (89.86%) and nheC (84.06%) with isolates belonging to groups IV and V having significant higher prevalence of hblACD and group IV of CytK genes. Strains from dairy products had significantly lower prevalence of CytK and hblACD genes compared to isolates from equipment and raw milk/bulk tanks. Genes related to sucrose metabolism were detected at higher frequency in isolates obtained from raw milk compared to strains from equipment and utensils. The population genomic analysis demonstrated the diversity of strains and variability of putative function among B. cereus group isolates in Brazilian dairy production, with large numbers of strains potentially able to cause foodborne illness. This detailed information will contribute to targeted interventions to reduce milk contamination and spoilage associated with B. cereus in Brazil.Univ Estadual Paulista, UNESP, Dept Med Vet Prevent & Reprod Anim, FCAV, Via Acesso Paulo Castellane S-N, BR-14884900 Sao Paulo, BrazilUniv Sao Paulo, Dept Med Vet, FZEA, Ave Duque de Caxias Norte 225, BR-13635900 Sao Paulo, BrazilUniv Bath, Dept Biol & Biochem, Milner Ctr Evolut, 4 South,Lab 0-39, Bath BA2 7AY, Avon, EnglandSwansea Univ, Med Sch, Swansea SA2 8PP, W Glam, WalesUniv Estadual Paulista, UNESP, Dept Med Vet Prevent & Reprod Anim, FCAV, Via Acesso Paulo Castellane S-N, BR-14884900 Sao Paulo, BrazilFAPESP: 2014/13104-1FAPESP: 2015/20874-0FAPESP: 2016/19214-

Numerical study of tensile tests conducted on systems with elastic-plastic films deposited onto elastic-plastic substrates

In this work, a series of two-dimensional plane-strain finite element analyses was conducted to further understand the stress distribution during tensile tests on coated systems. Besides the film and the substrate, the finite element model also considered a number of cracks perpendicular to the film/substrate interface. Different from analyses commonly found in the literature, the mechanical behavior of both film and substrate was considered elastic-perfectly plastic in part of the analyses. Together with the film yield stress and the number of film cracks, other variables that were considered were crack tip geometry, the distance between two consecutive cracks and the presence of an interlayer. The analysis was based on the normal stresses parallel to the loading axis (sigma(xx)), which are responsible for cohesive failures that are observed in the film during this type of test. Results indicated that some configurations studied in this work have significantly reduced the value of sigma(xx) at the film/substrate interface and close to the pre-defined crack tips. Furthermore, in all the cases studied the values of sigma(xx) were systematically larger at the film/substrate interface than at the film surface. (C) 2010 Elsevier B.V. All rights reserved

Paullinia cupana Mart var. sorbilis, guaraná, reduces cell proliferation and increases apoptosis of B16/F10 melanoma lung metastases in mice

We showed that guaraná (Paullinia cupana Mart var. sorbilis) had a chemopreventive effect on mouse hepatocarcinogenesis and reduced diethylnitrosamine-induced DNA damage. In the present experiment, we evaluated the effects of guaraná in an experimental metastasis model. Cultured B16/F10 melanoma cells (5 x '10 POT. 5' cells/animal) were injected into the tail vein of mice on the 7th day of guaraná treatment (2.0 mg P. cupana/g body weight, per gavage) and the animals were treated with guaraná daily up to 14 days until euthanasia (total treatment time: 21 days). Lung sections were obtained for morphometric analysis, apoptotic bodies were counted to calculate the apoptotic index and proliferating cell nuclear antigen-positive cells were counted to determine the proliferation index. Guaraná-treated (GUA) animals presented a 68.6% reduction in tumor burden area compared to control (CO) animals which were not treated with guaraná (CO: 0.84 '+ OU -' 0.26, N = 6; GUA: 0.27 '+ OU -' 0.24, N = 6; P = 0.0043), a 57.9% reduction in tumor proliferation index (CO: 23.75 '+ OU -' 20.54, N = 6; GUA: 9.99 '+ OU -' 3.93, N = 6; P = 0.026) and a 4.85-fold increase in apoptotic index (CO: 66.95 '+ OU -' 22.95, N = 6; GUA: 324.37 '+ OU -' 266.74 'AB/mm POT. 2', N = 6; P = 0.0152). In this mouse model, guaraná treatment decreased proliferation and increased apoptosis of tumor cells, consequently reducing the tumor burden area. We are currently investigating the molecular pathways of the effects of guaraná in cultured melanoma cells, regarding principally the cell cycle inhibitors and cyclinsFAPESP 05/54195-

Comparative genomic survey of Bacillus cereus sensu stricto isolates from the dairy production chain in Brazil

The genomes of 262 Bacillus cereus isolates were analyzed including 69 isolates sampled from equipment, raw milk and dairy products from Brazil. The population structure of isolates showed strains belonging to known phylogenetic groups II, III, IV, V and VI. Almost all the isolates obtained from dairy products belonged to group III. Investigation of specific alleles revealed high numbers of isolates carrying toxin-associated genes including cytK (53.62%), hblA (59.42%), hblC (44.93%), hblD (53.62%), nheA (84.06%), nheB (89.86%) and nheC (84.06%) with isolates belonging to groups IV and V having significant higher prevalence of hblACD and group IV of CytK genes. Strains from dairy products had significantly lower prevalence of CytK and hblACD genes compared to isolates from equipment and raw milk/bulk tanks. Genes related to sucrose metabolism were detected at higher frequency in isolates obtained from raw milk compared to strains from equipment and utensils. The population genomic analysis demonstrated the diversity of strains and variability of putative function among B. cereus group isolates in Brazilian dairy production, with large numbers of strains potentially able to cause foodborne illness. This detailed information will contribute to targeted interventions to reduce milk contamination and spoilage associated with B. cereus in Brazil.</p