Comportamento tribológico de revestimento multifuncional CrN-DLC em atmosferas de gases refrigerantes

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Florianópolis, 2010Um dos maiores motivadores de pesquisas mundiais, a redução do consumo de energia elétrica, é também motivo de inúmeras discussões relacionadas ao aquecimento global. No Brasil, no ano de 2008, 24% do consumo de energia elétrica foi demandado apenas no setor residencial, onde os equipamentos eletroeletrônicos são fortes responsáveis pelo consumo. Estima-se que, atualmente, somente a indústria de refrigeração seja responsável pelo consumo de 17% de toda a energia elétrica consumida nos Estados Unidos. Ultimamente um número elevado de pesquisas vêm sendo desenvolvidas, objetivando a redução do atrito e do desgaste. Estas pesquisas evoluíram desde sistemas lubrificados, passando pelo uso de aditivos e, finalmente, a utilização de revestimentos de lubrificantes sólidos. Muitas soluções encontradas esbarram em dificuldades de adequação de projetos e condições de aplicação severas. O uso de gases refrigerantes é um deles, uma vez que interfere diretamente na viscosidade de óleos lubrificantes e interfaces de contato de mancais. No presente estudo foi investigada a influencia de gases refrigerantes HFC134a e HC600a no comportamento tribológico de um revestimentos multifuncional de CrN-DLC. O objetivo deste estudo foi identificar tanto as perdas por atrito, quanto por desgaste deste revestimento em função das interações com os gases refrigerantes utilizados. Para entender tais propriedades foram propostos dois tipos de ensaios tribológicos: um para avaliar a durabilidade dos revestimentos em função de aplicação de cargas normais variáveis, e outro para determinação do coeficiente de atrito, bem como, da taxa de desgaste dos revestimentos nas duas atmosferas. Os corpos de prova e contracorpos foram caracterizados via espectroscopia Raman e EDS para identificar as modificações ocorridas nas interfaces de contato. Os resultados dos testes de durabilidade com gás refrigerante HFC134a apresentaram-se aproximadamente 40% superiores que os resultados dos testes com gás refrigerante HC600a. De modo similar, os valores de coeficiente de atrito também apresentaram valores maiores nos ensaios com gás refrigerante HFC134a. Entretanto, os resultados da taxa de desgaste do revestimento foram 50% menores nos testes com este gás refrigerante. Os contra corpos apresentaram uma taxa de desgaste muito mais elevada que nos corpos, atingindo valores acima de uma ordem de grandeza quando comparado aos valores da taxa de desgaste dos corpos. Através da caracterização química por espectroscopia Raman e EDS identificou-se a presença de compostos fluorados na tribocamada formada sobre a pista de desgaste do DLC, bem como, no contracorpo quando utilizado o gás refrigerante HFC134a. Entretanto, não foi detectada a transferência de DLC para as superfícies dos contracorpos. A presença de Flúor na tribocamada provavelmente está associada à degradação do gás refrigerante durante os ensaios tribológicos. Em contrapartida, nos ensaios com HC600a foi detectada a transferência de DLC para os contracorpos, conforme identificado nas análises via espectroscopia Raman. Todos os testes mostraram traços de oxigênio na tribocamada, os quais foram associados à presença de contaminantes adsorvidos nas amostras, bem como, à falta de hermeticidade da câmara de ensaio utilizada nos ensaios tribológicos.One of the major drivers of global research, reducing energy consumption, is also a matter of considerable discussion related to global warming. In Brazil, in 2008, 24% of electricity consumption was consumed only in the residential sector, where electric-electronic devices are responsible for most part of this consumption. It is estimated that only the refrigeration industry is responsible for consuming 17% of all electricity consumed in the United States. Recently a great number of studies are being developed, aiming the friction and wear reducing. These studies evolving since lubricated systems, passing through the usage of additives in lubricant oils, and finally, arriving in the use of coatings of solid lubricants. Many solutions are hindered by difficulties of adaptation in projects and severe application conditions. The use of refrigerant gases is one of them, since it directly interferes with the viscosity of lubricant oils and contact interfaces of bearings. In the present study it was investigated the influence of the refrigerant gases HFC134a and HC600a on the tribological behavior of a multifunctional coatings of CrN-DLC. The aim of this study was to identify since the friction losses, as the wear of this coating due to interactions with the proposed refrigerant gases. To understand these properties have been proposed two types of tribological tests: one to evaluate the durability of the coating as a function of variable applied normal loads, and another to determine the coefficient of friction as well as the wear rate of coatings in both atmospheres. The specimens and counter bodies were characterized via Raman spectroscopy and EDS to identify the modifications on the contact interfaces. The durability tests results with refrigerant HFC134a showed durability of about 40% higher than tests with HC600a. Similarly, the coefficient of friction values were also higher in trials with HFC134a. However, the results of the wear rate of the coating were 50% lower in tests of this refrigerant. Counter body analysis showed a wear rate even higher, amounting to approximately one order of magnitude. The chemical characterization by Raman spectroscopy and EDS revealed the presence of fluorinated compounds in tribolayer formed on the wear track of DLC and counter body with refrigerant gas HFC134a. In these trials were not detected the DLC transference to the counter body surfaces. The presence of fluoride in tribolayer may be related to degradation of the refrigerant gas during the tribological tests. In contrast, in trials with HC600a were detected transferring of the DLC to the counter body, as presented in the analysis via Raman spectroscopy. All tests showed traces of oxygen in tribolayer, associated with contaminants adsorbed on the samples and the lack of hermeticity of the test chamber used in the tribological tests

Genesis and stability of tribolayers in solid lubrication: case of pair DLC-stainless steel

AbstractThe morphology, dimensions and chemical composition of tribolayers strongly depend on the pressures and temperatures acting on the contact. They are formed by reactions between surfaces in contact with each other as well as with the atmosphere, lubricants and possible contaminants. In this paper, the influence of test time (180, 500, 1000 and 2500h) on the formation and characteristics of tribolayers in pairs of DLC-stainless steel that were tested under an atmosphere of refrigerant gas R134a and without lubricating oil was analyzed. The characterization was performed using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) (morphology and chemical composition) and white light interferometry (thickness). The tribolayer thicknesses ranged from 100 to 500nm, and they were composed of elements originating from mutual transfers between the tribological pairs, as well as oxides that were more pronounced on the stainless steel surface. The results show that the tribolayers are chemically stable, maintaining the same composition over time, and their thicknesses remained constant after 1000h of testing

Sorption of aspartic and glutamic aminoacids on calcined hydrotalcite

Sorption of aspartic and glutamic aminoacids by regeneration of calcined hydrotalcite is reported. Hydrotalcite was synthesized by coprecipitation and calcined at 773 K. Sorption experiments were performed at 298 K and 310 K, and the results reveal that at low aminoacids equilibrium concentrations, intercalation of hydroxyl anions takes place while at high equilibrium concentrations, the sorption process occur by means re-hydration and aminoacids intercalation of hydrotalcite. The results also suggested that Asp and Glu sorption is a temperature dependent process. The amount of sorbed amino acid decreases as the temperature increase. The effect is more pronounced for Glu sorption probably due to its higher hydrophobic character, which makes the sorption more difficult in comparison with sorption of Asp at higher temperature.The authors thank the Brazilian agencies CAPES and CNPq for financial support

Exposure of periodontal ligament progenitor cells to lipopolysaccharide from Escherichia coli changes osteoblast differentiation pattern

Periodontal ligament mesenchymal stem cells (PDLMSCs) are an important alternative source of adult stem cells and may be applied for periodontal tissue regeneration, neuroregenerative medicine, and heart valve tissue engineering. However, little is known about the impact of bacterial toxins on the biological properties of PDLSMSCs, including self-renewal, differentiation, and synthesis of extracellular matrix. This study investigated whether proliferation, expression of pro-inflammatory cytokines, and osteogenic differentiation of CD105-enriched PDL progenitor cell populations (PDL-CD105+ cells) would be affected by exposure to bacterial lipopolysaccharide fromEscherichia coli (EcLPS). Toll-like receptor 4 (TLR4) expression was assessed in PDL-CD105+ cells by the immunostaining technique and confirmed using Western blotting assay. Afterwards, these cells were exposed to EcLPS, and the following assays were carried out: (i) cell viability using MTS; (ii) expression of the interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor alpha (TNF-α) genes; (iii) osteoblast differentiation assessed by mineralization in vitro, and by mRNA levels of run-related transcription factor-2 (RUNX2), alkaline phosphatase (ALP) and osteocalcin (OCN) determined by quantitative PCR.PDL-CD105+ cells were identified as positive for TLR4. EcLPS did not affect cell viability, but induced a significant increase of transcripts for IL-6 and IL-8. Under osteogenic condition, PDL-CD105+ cells exposed to EcLPS presented an increase of mineralized matrix deposition and higher RUNX2 and ALP mRNA levels when compared to the control group. These results provide evidence that CD105-enriched PDL progenitor cells are able to adapt to continuous Escherichia coli endotoxin challenge, leading to an upregulation of osteogenic activities232FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPNão te

Exposure of periodontal ligament progenitor cells to lipopolysaccharide from Escherichia coli changes osteoblast differentiation pattern

Periodontal ligament mesenchymal stem cells (PDLMSCs) are an important alternative source of adult stem cells and may be applied for periodontal tissue regeneration, neuroregenerative medicine, and heart valve tissue engineering. However, little is known about the impact of bacterial toxins on the biological properties of PDLSMSCs, including self-renewal, differentiation, and synthesis of extracellular matrix. Objective : This study investigated whether proliferation, expression of pro-inflammatory cytokines, and osteogenic differentiation of CD105-enriched PDL progenitor cell populations (PDL-CD105+ cells) would be affected by exposure to bacterial lipopolysaccharide from Escherichia coli (EcLPS). Material and Methods : Toll-like receptor 4 (TLR4) expression was assessed in PDL-CD105+ cells by the immunostaining technique and confirmed using Western blotting assay. Afterwards, these cells were exposed to EcLPS, and the following assays were carried out: (i) cell viability using MTS; (ii) expression of the interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor alpha (TNF-α) genes; (iii) osteoblast differentiation assessed by mineralization in vitro, and by mRNA levels of run-related transcription factor-2 (RUNX2), alkaline phosphatase (ALP) and osteocalcin (OCN) determined by quantitative PCR. Results : PDL-CD105+ cells were identified as positive for TLR4. EcLPS did not affect cell viability, but induced a significant increase of transcripts for IL-6 and IL-8. Under osteogenic condition, PDL-CD105+ cells exposed to EcLPS presented an increase of mineralized matrix deposition and higher RUNX2 and ALP mRNA levels when compared to the control group. Conclusions : These results provide evidence that CD105-enriched PDL progenitor cells are able to adapt to continuous Escherichia coli endotoxin challenge, leading to an upregulation of osteogenic activities

Transcriptome profile of highly osteoblastic/cementoblastic periodontal ligament cell clones

Heterogeneous cell populations of osteo/cementoblastic (O/C) or fibroblastic phenotypes constitute the periodontal dental ligament (PDL). A better understanding of these PDL cell subpopulations is essential to propose regenerative approaches based on a sound biological rationale. Objective: Our study aimed to clarify the differential transcriptome profile of PDL cells poised to differentiate into the O/C cell lineage. Methodology: To characterize periodontal-derived cells with distinct differentiation capacities, single-cell-derived clones were isolated from adult human PDL progenitor cells and their potential to differentiate into osteo/cementoblastic (O/C) phenotype (C-O clones) or fibroblastic phenotype (C-F clones) was assessed in vitro. The transcriptome profile of the clonal cell lines in standard medium cultivation was evaluated using next-generation sequencing technology (RNA-seq). Over 230 differentially expressed genes (DEG) were identified, in which C-O clones showed a higher number of upregulated genes (193) and 42 downregulated genes. Results: The upregulated genes were associated with the Cadherin and Wnt signaling pathways as well as annotated biological processes, including “anatomical structure development” and “cell adhesion.” Both transcriptome and RT-qPCR showed up-regulation of WNT2, WNT16, and WIF1 in C-O clones. Conclusions: This comprehensive transcriptomic assessment of human PDL progenitor cells revealed that expression of transcripts related to the biological process “anatomical structure development,” Cadherin signaling, and Wnt signaling can identify PDL cells with a higher potential to commit to the O/C phenotype. A better understanding of these pathways and their function in O/C differentiation will help to improve protocols for periodontal regenerative therapies

CONSIDERAÇÕES NA ANESTESIA DE ANIMAIS DE LABORATÓRIO

A anestesia em animais de laboratório tem como diretriz de conduzir os experimentos científicos com a mais rigorosa maestria, de modo a gerar mínimo estresse aos animais e por outro lado, ter a possibilidade de coletar dados com excelência. A história da medicina possibilita desvendarmos os caminhos pelos quais a anestesiologia se guiou de modo a incorporar a ética humana e animal juntamente com o rigor metodológico e científico. Esta revisão surge a partir de pesquisa nos bancos de dados Pubmed, Scielo e Bireme, juntamente com consulta literária. Os achados apontam para as principais particularidades entre as espécies e técnicas de anestesiologia utilizados nos dias atuais. Foram descritos os principais fármacos e vias para utilização em camundongos, ratos wistar e coelhos. Os resultados encontrados nesta revisão confirmam a necessidade de compreender as diferenças entre as espécies e o conhecimento farmacológico para realizar a conduta anestésica adequada para cada espécie

Association of rs142548867 (EEFSEC) and periodontitis Grade C in a young Brazilian population

Periodontitis Stage III-IV, Grade C (PerioC) is a severe form of Periodontitis. The individual genetic background has been shown to be an important etiopathogenic factor for the development of this disease in young, systemically healthy, and non-smokers patients. Recently, after exome sequencing of families with a history of the disease, PerioC was associated with three single nucleotide variations (SNVs) – rs142548867 (EEFSEC), rs574301770 (ZNF136), and rs72821893 (KRT25) – which were classified as deleterious or possibly harmful by prediction algorithms. Objective: Seeking to validate these findings in a cohort evaluation, this study aims to characterize the allele and genotypic frequency of the SNVs rs142548867, rs574301770, and rs72821893 in the Brazilian population with PerioC and who were periodontally healthy (PH). Methodology: Thus, epithelial oral cells from 200 PerioC and 196 PH patients were harvested at three distinct centers at the Brazilian Southern region, their DNA were extracted, and the SNVs rs142548867, rs574301770, rs72821893 were genotyped using 5′-nuclease allelic discrimination assay. Differences in allele and genotype frequencies were analyzed using Fisher’s Exact Test. Only the SNV rs142548867 (C > T) was associated with PerioC. Results: The CT genotype was detected more frequently in patients with PerioC when compared with PH subjects (6% and 0.5% respectively), being significantly associated with PerioC (odds ratio 11.76, p=0.02). Conclusion: rs142548867 represents a potential risk for the occurrence of this disease in the Brazilian population

MÉTODOS DE SECAGEM DE AMOSTRAS DE FOLHAS DE CAPIM BRACHIÁRIA, CANA-DE-AÇÚCAR E GOIABEIRA NOS TEORES DE MACRONUTRIENTES

A secagem de amostras de folhas em forno microondas pode ser promissora se não afetar os teores dos nutrientes nas amostras, comparada ao método convencional em estufa. Assim, o presente trabalho objetivou avaliar os efeitos da secagem de amostras de folhas das culturas de capim-braquiária, cana-de-açúcar e goiabeira, utilizando o forno microondas e a estufa sobre os teores foliares de macronutrientes. Para isto, realizou um estudo em condições de laboratório, na UNESP Câmpus de Jaboticabal. Os tratamentos foram constituídos por um fatorial 3x2, sendo três culturas, o capim brachiária, a cana-de-açúcar e a goiabeira e dois métodos de secagem, o forno microondas e a estufa de circulação forçada de ar, dispostos em delineamento inteiramente causalizado com seis repetições. Após a secagem do material do material vegetal, determinando-se os teores foliares dos macronutrientes. Os métodos de secagem não afetaram os teores foliares de nitrogênio, fósforo, potássio e magnésio das culturas de capim-braquiária, goiaba e cana-de-açúcar. Para os teores foliares de enxofre e cálcio o uso do forno microondas apresentou maiores valores destes nutrientes para as três culturas, exceto o último nutriente que foi apenas para a folha da goiabeira. O uso da secagem das folhas em forno microondas apresenta viabilidade para uso em laboratório, entretanto, é importante mais pesquisas em diferentes tecidos vegetais (culturas)

Partograma: instrumento de monitoreo en la atención multidisciplinar

Introduction: A partograph is the graphic representation of labor from its early stages, which allows observing the changes during the labor process. Objective: To determine partograph-related knowledge among nurses and doctors in a maternity hospital. Materials and Methods: A cross-sectional study was conducted with nurses and doctors from a maternity hospital in northeastern Brazil. The sample consisted of 8 nurses and 39 doctors. Results: Most health professionals have taken courses or training related to the instrument itself. However, there were some doubts about partograph handling in 27.6% of cases. Work overload, lack of knowledge to fill out the instrument and lack of continuity affected this matter. As for the situations in which the instrument should be used, women in active labor and normal labor were listed. Discussion: The importance and necessity of partographs during labor are beyond question. The information obtained through this instrument guides professionals through the next steps of labor and delivery. Conclusion: The use of partograph is considered essential in labor and knowledge related to its handling is critical in practical settings. However, the use of this instrument is just beginning in the maternity ward. How to cite this article: Medeiros, Anderson Brito de; Freire, Izaura Luzia Silvério; Santos, Fernanda Rafaela dos; Silva, Bárbara Coeli Oliveira da; Batista, George Felipe de Moura; Menezes, Márcio Moreira de. Partograma: instrumento de segurança no cuidado multidisciplinar. Revista Cuidarte. 2020; 11(3): e1046. http://dx.doi.org/10.15649/cuidarte.1046     Introdução: O partograma é um traçado de representação gráfica do trabalho de parto que concebe o desencadeamento de sua evolução, permitindo a visualização das alterações no decorrer do partejar. O estudo objetivou descrever o conhecimento sobre partograma por enfermeiros e médicos de uma maternidade escola. Materiais e Métodos: Estudo transversal realizado com enfermeiros e médicos em maternidade escola do nordeste brasileiro. A amostra foi constituída por 8 enfermeiros e 39 médicos. Resultados: Observou-se que a maior parte já fez curso ou treinamento relacionado à ferramenta. Todavia, em 27,6% dos casos ocorrem dúvidas sobre seu manejo. Sobrecarga no plantão; falta de conhecimento no preenchimento e ausência de continuidade foram considerados aspectos dificultadores. Quanto às situações nas quais se deve abrir o instrumento, as mais citadas foram gestantes em trabalho de parto na fase ativa e trabalho de parto normal. Discussão: É indiscutível a importância e necessidade do partograma no decorrer do trabalho de parto. As informações retiradas a partir dele orientam o profissional para os próximos passos a serem seguidos. Conclusão: Acredita-se que o uso do partograma é essencial no processo de parto, e que os conhecimentos referentes à sua utilização são fundamentais na prática. Contudo, mesmo na maternidade, o uso da ferramenta é incipiente. Como citar este artigo: Medeiros, Anderson Brito de; Freire, Izaura Luzia Silvério; Santos, Fernanda Rafaela dos; Silva, Bárbara Coeli Oliveira da; Batista, George Felipe de Moura; Menezes, Márcio Moreira de. Partograma: instrumento de segurança no cuidado multidisciplinar. Revista Cuidarte. 2020; 11(3): e1046. http://dx.doi.org/10.15649/cuidarte.1046    Introducción: El partograma es la representación gráfica del trabajo de parto desde el inicio de su evolución, lo que permite visualizar los cambios durante el proceso de parto. Objetivo: Identificar los conocimientos relacionados con el partograma por parte de los enfermeros y médicos de una clínica de maternidad. Materiales y métodos: Se realizó un estudio transversal con enfermeros y médicos de una clínica de maternidad del noreste de Brasil. La muestra estuvo compuesta por 8 enfermeros y 39 médicos. Resultados: Se observó que la mayoría del personal de salud han tomado cursos o capacitación relacionados con el instrumento en mención. Sin embargo, en el 27.6% de los casos hay dudas sobre el manejo del partograma. La sobrecarga laboral, la falta de conocimiento para diligenciar el instrumento y la falta de continuidad contribuyeron a esta problemática. En cuanto a las situaciones en las que se debe usar el instrumento, se mencionó a las mujeres que se encuentran en trabajo de parto en fase activa y en el trabajo de parto normal. Discusión: La importancia y necesidad del partograma durante el trabajo de parto es indiscutible. La información que se obtiene a través de este instrumento guía al profesional en los siguientes pasos del parto. Conclusión: Se considera que el uso del partograma es esencial en el trabajo de parto y que el conocimiento sobre su manejo es crítico en la práctica. Sin embargo, el uso del instrumento es incipiente en la maternidad. Como citar este ar´tículo: Medeiros, Anderson Brito de; Freire, Izaura Luzia Silvério; Santos, Fernanda Rafaela dos; Silva, Bárbara Coeli Oliveira da; Batista, George Felipe de Moura; Menezes, Márcio Moreira de. Partograma: instrumento de segurança no cuidado multidisciplinar. Revista Cuidarte. 2020; 11(3): e1046. http://dx.doi.org/10.15649/cuidarte.1046    &nbsp