Análise microestrutural e caracterização mecânica do aço AISI 4350 submetido a diferentes tratamentos térmicos

The multiphase steels are gaining increasing attention in scientific studies because of the different mechanical and microstructural properties that the material can achieve under different thermomechanical and heat treatments that can be submitted. In the present study, it was made a microstructural study thru the triple attack technic associated with optical microscopy and mechanical characterization of medium carbon AISI 4350 steel thru a tensile strength test, subjected to three routes of heat treatment: annealing, quenching and tempering and isothermal annealing. It was verified the predominance of ferrite-perlite constituent in the specimen annealed, martensitic in the quenched and tempered specimen and bainitic in the annealed isothermally specimen. The annealed material showed a higher ductility, while the hardened and tempered specimen showed the highest hardness and ultimately the bainitic specimen showed a combination of the two abovementioned mechanical properties. Thus, we proved that the multiphase steel SAE 4350 can be a versatile material with great potential for various industrial applications

Conforto térmico em cidades de porte médio no oeste paulista: os casos de Presidente Prudente e Marília

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Conforto térmico de edificações: análise crítica das tecnologias existentes

The rising in greenhouse gases emission as consequence of industrial expansion especially in developing countries is appointed as one of those reasons responsible for global warming. High-level temperatures are set as responsible for low productivity and high levels of discomfort. With the increase of worldwide energy demand, due to the population growth, this work aims to be an introductory text revising the current ventilation (mechanical and natural) and refrigeration technologies as well as low energy cooling techniques and architectural alternatives that seeks offering good ventilation and ideal buildings temperatures, making them sustainable. In addition, the text deals with the measurement instruments used to evaluate the parameters defined by international and national standards. At last, a case of study applies few concepts and technologies described in the text, introducing the results achieved, the limitations and suggestions to future works

Tratamento térmico de normalização em tampos de vasos de pressão fabricados de material P275NH

In a market environment increasingly competitive, the companies need to control of this process accurately, avoiding rework or rejection of materials during industrialization. This can be achieved by defining procedure that assure the maintenance of the materials characteristics, as specified initially in the projects. This graduation work has the objective of defining the best heat treatment parameter of normalizing for Heads, part of a pressure vessel, formed in P275NH material. The methodology applied is based on the execution of a sequence of Heat Treatments, using different parameters. The process variables were the cooling velocity, the hold time and the hold temperature variation. As a result of this study, it is noticed that the mechanical properties of the materials are strongly influenced by the hold temperature variation and by the cooling velocity, both determined for the heat treatment cycle

Análise do perfil de dureza e microestrutura de um aço forjado AISI A2 submetido a tratamento térmico com resfriamento em água

Due to the large use of steel in several processes around the world, there is the increasingly concern to find new materials and/or optimization and improvement of the processes, as the need to reduce the cost and a productivity increase in the primary industry, such as the siderurgy. The rolling is the most used mechanical process in the world and therefore is required the development of new tools in high volume and with optimum characteristics to support the market demand. Forged rolls used are for rolling. These rolls have heat treatment that has the purpose to achieve the appropriated mechanical properties to support the variables of the rolling process. The objective of this work is to analyze the hardness profile and the microstructure a tool steel similar to AISI A2, forged in an opened die process and submitted to heat treatment with water-cooling. The results allowed plotting a hardness profile and performing a microstructure analysis, and whereby to confirm that the heat treatment is not a quenching, but it is a material beneficiation by the hardening of superficial layer, since there is no martensitic microstructure. Therefore, this paper provides the support to future studies about the possibility to perform enhancements in this thermal heat made in the rolls produced at Gerdau Plant in Pindamonhangaba

Differential expression of CD90 and CD14 stem cell markers in malignant breast cancer cell lines

The recently emerged concept of cancer stem cell (CSC) has led to a new hypothesis on the basis for tumor progression. Basically, the CSC theory hypothesizes the presence of a hierarchically organized and relatively rare cell population, which is responsible for tumor initiation, self-renewal, and maintenance, in addition to accumulation of mutation and resistance to chemotherapy. CSCs have recently been described in breast cancer. Different genetic markers have been used to isolate breast CSCs, none of which have been correlated with the tumorigenicity or metastatic potential of the cells, limiting their precise characterization and clinical application in the development of therapeutic protocols. Here, we sought for subpopulations of CSCs by analyzing 10 judiciously chosen stem cell markers in a normal breast cell line (MCF10-A) and in four human breast cancer cell lines (MCF-7, MDA-MB-231, MDA-MB-435, and Hs578-T) displaying different degrees of metastatic and invasiveness potential. We were able to identify two markers, which are differentially expressed in nontumorigenic versus tumor cells. The CD90 marker was highly expressed in the malignant cell lines. Interestingly, the CD14 molecule displayed higher expression levels in the nontumorigenic cell line. Therefore, we demonstrated that these two markers, which are more commonly used to isolate and characterize stem cells, are differentially expressed in breast tumor cells, when compared with nontumorigenic breast cells. (C) 2012 International Society for Advancement of Cytometry

Stem cells in embryonic skin development

The skin is a complex stratified organ which acts not only as a permeability barrier and defense against external agents, but also has essential thermoregulatory, sensory and metabolic functions. Due to its high versatility and activity, the skin undergoes continuous self-renewal to repair damaged tissue and replace old cells. Consequently, the skin is a reservoir for adult stem cells of different embryonic origins. Skin stem cell populations reside in the adult hair follicle, sebaceous gland, dermis and epidermis. However, the origin of most of the stem cell populations found in the adult epidermis is still unknown. Far more unknown is the embryonic origin of other stem cells that populate the other layers of this tissue. In this review we attempt to clarify the emergence, structure, markers and embryonic development of diverse populations of stem cells from the epidermis, dermis and related appendages such as the sebaceous gland and hair follicle.

New insights in osteogenic differentiation revealed by mass spectrometric assessment of phosphorylated substrates in murine skin mesenchymal cells

Abstract Background Bone fractures and loss represent significant costs for the public health system and often affect the patients quality of life, therefore, understanding the molecular basis for bone regeneration is essential. Cytokines, such as IL-6, IL-10 and TNFα, secreted by inflammatory cells at the lesion site, at the very beginning of the repair process, act as chemotactic factors for mesenchymal stem cells, which proliferate and differentiate into osteoblasts through the autocrine and paracrine action of bone morphogenetic proteins (BMPs), mainly BMP-2. Although it is known that BMP-2 binds to ActRI/BMPR and activates the SMAD 1/5/8 downstream effectors, little is known about the intracellular mechanisms participating in osteoblastic differentiation. We assessed differences in the phosphorylation status of different cellular proteins upon BMP-2 osteogenic induction of isolated murine skin mesenchymal stem cells using Triplex Stable Isotope Dimethyl Labeling coupled with LC/MS. Results From 150 μg of starting material, 2,264 proteins were identified and quantified at five different time points, 235 of which are differentially phosphorylated. Kinase motif analysis showed that several substrates display phosphorylation sites for Casein Kinase, p38, CDK and JNK. Gene ontology analysis showed an increase in biological processes related with signaling and differentiation at early time points after BMP2 induction. Moreover, proteins involved in cytoskeleton rearrangement, Wnt and Ras pathways were found to be differentially phosphorylated during all timepoints studied. Conclusions Taken together, these data, allow new insights on the intracellular substrates which are phosphorylated early on during differentiation to BMP2-driven osteoblastic differentiation of skin-derived mesenchymal stem cells.

La costituzione augustea

Schemi riassuntivi dell'ordinamento augusteo discussi, spiegati e presentati a lezione. Tali schemi sono da intendersi come mero supporto al manuale e alle lezioni