Pontifícia Universidade Católica do Paraná (PUC-PR)
Recent publications
Background: Smile esthetics has a strong influence on perception, attractiveness, and personal characteristics. It is unknown how malocclusions may influence the appearance of the individual's smile. This study aimed to investigate whether malocclusion affects the visual perception of esthetics, age, employability, honesty, intelligence and to meet its obligation in time in middle-aged adults. Facial frontal smiling photographs of a male and a female middle-aged adult with 3 different malocclusions were shown to and evaluated by 90 laypeople (non-dentists), divided into groups: young adults (14-44 years), middle-aged adults (45-59 years), and elders (over 60 years). The index of treatment need (IOTN) was used, and IOTN 1, 5, and 8 images were created in Photoshop using the male and female photographs. In total, 6 photographs were evaluated, 3 areas of interest (AOI)-eyes, nose, and mouth-were created for statistical comparison. The Ogama and Eye Tribe tracker were used in conjunction to measure eye tracking. A visual analog scale (VAS) was employed with a questionnaire surveying individuals' perception of age, employability, honesty, intelligence, and ability to meet obligations. Kruskal-Wallis, one-way analysis of variance, Pearson's-chi-squared, and Pearson correlation test were applied. Results: No statistical difference was found in complete fixation time and time until the first fixation for each AOI for eye-tracking. VAS showed statistical differences in the male and female IOTN 1 images when compared with the IOTN 5 and 8 for both models, and there was no difference between genders in the IOTN 1. As the perceived age of the model increased, the chances of getting hired decreased. Employability, honesty, intelligence, and ability to meet obligations showed higher values for IOTN 1. There were significant differences between age ranges; perception of intelligence in the female IOTN 1 model (p = 0.002) and IOTN 8 model (p < 0.001) and honesty between young adults and middle-aged adults in the male IOTN 1 and 8 images (p < 0.001). Conclusions: There was a difference between age groups in the perception of honesty and intelligence. A well-balanced and attractive was perceived as more youthful and attractive in both genders and may increase the chance of being selected for a job interview or being hired.
Background Nonalcoholic fatty liver disease (NAFLD) is a silent disease with increasing prevalence. High levels of serum uric acid (SUA) have been associated with cardiometabolic diseases, yet the possible association between SUA levels and NAFLD is not elucidated. This article aim is to evaluate the possible association between SUA and NAFLD in a Brazilian population. Methods This retrospective study evaluated patients submitted to two evaluations between 2015 and 2016 at a preventive medicine service. The diagnosis of NAFLD was performed through abdominal ultrasound, and its progression was defined as favorable or unfavorable according to the degrees of steatosis. Patients with hyperthyroidism, pregnancy, viral hepatitis, use of methotrexate or anabolic steroids, significant alcohol consumption were excluded. Possible confounding factors were evaluated through a multivariate model. Results A total of 279 patients were included in the final sample. In the first evaluation, 20.1% were women and the mean age was 46.9 (± 7.9) years, with a mean body mass index of 27.3 (± 4.0) kg/m ² . About 26.9% of the individuals were diagnosed with NAFLD, and the mean of SUA levels was 5.7 (± 1.4) mg/dL; a favorable progression of NAFLD was observed in 79.2% of the patients, and the SUA levels at baseline were not significantly associated with the NAFLD progression ( p = 0.43). Conclusions Despite NAFLD high prevalence, SUA levels were not significantly associated with NAFLD progression in one year in this sample.
During neuronal differentiation, neuroprogenitor cells become polarized, change shape, extend axons, and form complex dendritic trees. While growing, axons are guided by molecular cues to their final destination, where they establish synaptic connections with other neuronal cells. Several layers of regulation are integrated to control neuronal development properly. Although control of mRNA translation plays an essential role in mammalian gene expression, how it contributes temporarily to the modulation of later stages of neuronal differentiation remains poorly understood. Here, we investigated how translation control affects pathways and processes essential for neuronal maturation, using H9-derived human neuro progenitor cells differentiated into neurons as a model. Through Ribosome Profiling (Riboseq) combined with RNA sequencing (RNAseq) analysis, we found that translation control regulates the expression of critical hub genes. Fundamental synaptic vesicle secretion genes belonging to SNARE complex, Rab family members, and vesicle acidification ATPases are strongly translationally regulated in developing neurons. Translational control also participates in neuronal metabolism modulation, particularly affecting genes involved in the TCA cycle and glutamate synthesis/catabolism. Importantly, we found translation regulation of several critical genes with fundamental roles regulating actin and microtubule cytoskeleton pathways, critical to neurite generation, spine formation, axon guidance, and circuit formation. Our results show that translational control dynamically integrates important signals in neurons, regulating several aspects of its development and biology.
Background We hypothesize that adding sonication cycles to the process of decellularization of cadaveric human peripheral nerves will increase the removal of cell debris and myelin sheath, increasing their utility as allografts.Methods Our aim of this study was to develop a decellularization protocol that allows the removal of cells and myelin sheath without detrimental effects on nerve architecture. Segments of ulnar and median nerves from human donors, isolated both before and after cardiac arrest, were subjected to two methods of decellularization: two-detergent-based (M1) and the same method with sonication added (M2). We evaluated the histology of unprocessed and decellularized nerves (n = 24 per group) for general morphology, presence of cell nuclei, nuclear remnants, collagen fibers, and myelin. We performed immunohistochemistry to verify the removal of Schwann cells associated with histomorphometry. We used scanning electron microscopy (EM) to evaluate the ultrastructure of both native and decellularized nerves. The efficacy of decellularization was assessed by analysis of genomic DNA.ResultsHistology confirmed that both decellularization protocols were adequate and maintained natural nerve architecture. Scanning EM showed that 3D ultrastructural architecture also was maintained. Histomorphometric parameters showed a more complete removal of the myelin with the M2 protocol than with M1 (p = 0.009). Fiber diameter and density were not modified by decellularization methods.Conclusions Sonication can be a complementary method to decellularization of peripheral nerve allografts with sonication increasing the effectiveness of detergent‐based protocols for the removal of unwanted cellular components from peripheral nerve allografts.
The decellularization of bovine bone has emerged as a strategy for the repair, replacement, and regeneration of bone defects. To evaluate the effects of a new protocol of bone decellularization and its impact on the structure and collagen scaffold. Cancellous bone from bovine femur was dissected in fragments and decellularized based on protocol of multiple steps. The residual protein levels, histological, morphometric, and scanning electronic microscopy analyses were carried out to evaluate the effects of decellularization and the impact on the structure and collagen scaffold. A cytotoxicity assay was performed. Residual protein analysis showed an important removal of bone marrow components and cell debris from the bone. Sections revealed that collagen fibers presented integrity and absence of cells in the decellularized bone. Sirius Red-stained sections of collagen fiber collagen matrix were maintained after decellularization. Scanning electron microscopy revealed that the main bone structure, despite being irregular, was maintained in both groups, with no significant visual differences between the surface characteristics according to the groups. Decellularized bovine bone demonstrated a degree of toxicity of 3, indicating moderate reactivity. The present data demonstrate that the main bone structure was maintained. Additionally, the chemical and physical treatments were able to remove cellular debris, and extracellular matrix architecture and collagen were preserved. However, the tissue showed moderate toxicity.
Background Diabetic retinopathy (DR) is a chronic diabetes complication. People with Type 2 Diabetes Mellitus (T2DM) have two times the risk for dementia, suggesting it is a new chronic diabetes complication Objective Evaluate the association of DR with cognitive performance in a T2DM population. Methods Cross-sectional study with 251 T2DM adults from whom socio-demographic, clinical, laboratory data, a screening test for depression symptoms [Patient Health Questionaire-9 (PHQ-9)], Mini-Mental State Examination (MMSE), Semantic Verbal Fluency Test, Trail Making Test A and B, Word Memory test were collected and performed. All cognitive test scores were converted into Global Cognition z-Score [GCS(z)]. The association between GCS(z) < 0 with DR was performed using a multivariate binary logistic regression model adjusted for age ≥ 65 years, school years ≤ 6 years, DM duration ≥ 10 years, depression symptoms score > 9 at PHQ-9, arterial hypertension, physical activity, diabetic retinopathy, macular edema, and cardiovascular disease. Results After exclusions, the 251 eligible patients were 56.6% female, with a mean age of 61.1(±9.8) years, DM duration of 12.6(±8.9) years, and 7.6(±4.2) years of school education. DR prevalence was 46.5%. Multivariate Logistic Regression Model showed an association between DR and GCS(z) < 0, with odds ratio (CI95%) of 2.50 (1.18-5.34), adjusted for age, low education level, arterial hypertension and depression symptoms [OD and CI95% respectively: 5.46(2.42-12.34); 12.19(5.62-26.46); 2.55(0.88-7.39); 3.53(1.55-8.07)]. Conclusion In this T2DM population, having DR increased the chance for worse cognitive performance even when adjusted for age, low education level, presence of arterial hypertension, and depression symptoms.
Paracoccidioidomycosis (PCM), a systemic mycosis caused by the fungus Paracoccidioides spp. is the most prevalent fungal infection among immunocompetent patients in Latin America. The estimated frequency of central nervous system (CNS) involvement among the human immunodeficiency virus (HIV)/PCM-positive population is 2.5%. We aimed to address the impact of neuroparacoccidioidomycosis (NPCM) and HIV/NPCM co-infection on the tight junctions (TJ) and adherens junction (AJ) proteins of the CNS. Four CNS formalin-fixed paraffin-embedded (FFPE) tissue specimens were studied: NPCM, NPCM/HIV co-infection, HIV-positive without opportunistic CNS infection, and normal brain autopsy (negative control). Immunohistochemistry was used to analyze the endothelial cells and astrocytes expressions of TJ markers: claudins (CLDN)-1, -3, -5 and occludin; AJ markers: β-catenin and E-cadherin; and pericyte marker: alpha-smooth muscle actin. FFPE CNS tissue specimens were analyzed using the immunoperoxidase assay. CLDN-5 expression in the capillaries of the HIV/NPCM coinfected tissues (mixed clinical form of PCM) was lower than that in the capillaries of the HIV or NPCM monoinfected (chronic clinical form of PCM) tissues. A marked decrease in CLDN-5 expression and a compensatory increase in CLDN-1 expression in the NPCM/HIV co-infection tissue samples was observed. The authors suggest that Paracoccidioides spp. crosses the blood–brain barrier through paracellular pathway, owing to the alteration in the CLDN expression, or inside the macrophages (Trojan horse).
Automatic monitoring of flying insects enables quick and efficient observations and management of ecologically and economically important targets such as pollinators, disease vectors, and agricultural pests. Studies on this topic mainly cover the tasks of detection and identification or classification, the latter often guided by the flight sounds of insects. This paper uses domain knowledge and taxonomy information to classify bee and wasp species based on abiotic variables and wing-beat data that change depending on climatic-environmental conditions. We survey the state-of-the-art in hierarchical classification and evaluate the most popular local and global methods for this task on flight data from nine hymenopteran species. We collected the data in Brazilian fields employing an inexpensive optical sensor. Our results show that it is possible to hierarchically classify groups of specimens per species, species, and groups of species according to their wing-beat data at different temperature and relative humidity levels with at least 91% accuracy. Besides benefiting research aimed at building insect classifiers adaptable to natural variations in the environment, this study is a vital step in a series of efforts to design non-invasive species monitoring techniques.
Resumo Objetivo Avaliar a sensibilidade e a especificidade da reação em cadeia de polimerase em tempo real quantitativa (quantitative real-time polymerase chain reaction, qPCR, em inglês) para a triagem do gene rDNA 16S, com a utilização do fluido sonicado de implantes ortopédicos. Métodos Um estudo retrospectivo foi realizado em 73 fluidos sonicados obtidos de pacientes com infecção associada aos implantes ortopédicos. As amostras foram submetidas a cultura convencional e a teste molecular utilizando ionização e dessorção a laser assistida por matriz com espectrometria de massa por tempo de voo (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, MALDI-TOF MS, em inglês) e qPCR para o gene rDNA 16S. Os valores limiares do ciclo foram usados para definir um ponto de corte para a qPCR do gene rDNA 16S para culturas negativas e positivas. Resultados Não foram observadas diferenças estatísticas entre os grupos de cultura positiva e negativa com base no tempo desde a primeira cirurgia até a infecção (p = 0,958), na idade (p = 0,269), ou nas comorbidades em geral. No entanto, uma diferença estatística foi encontrada entre a duração média do uso de antibióticos antes da remoção do dispositivo (3,41 versus 0,94; p = 0,016). O DNA bacteriano foi identificado em todas as amostras dos fluidos sonicados. Os limiares do ciclo médio de culturas positivas e negativas foram de 25,6 e 27,3, respectivamente (p < 0,001). Como uma ferramenta de diagnóstico, um corte do limite do ciclo de 26,89 demonstrou uma área sob a curva da característica de operação do receptor de 0,877 (p ≤ 0,001). Conclusão A presença de agentes antimicrobianos por mais de 72 horas diminuiu a positividade da cultura, mas não influenciou os resultados da qPCR. Apesar disso, a amplificação do rDNA 16S pode sobrestimar o diagnóstico de infecção.
Ensuring the protection of natural vegetation is a complex challenge that demands a mix of policies. In Brazil, conservation on private land relies on large-scale command-and-control instruments and a few Payments for Ecosystem Services schemes, with taxation playing a minimal role for conservation. The Rural Land Tax (Imposto Territorial Rural, ITR) is a long-established rural tax created to stimulate pasture productivity and promoting social, agricultural, and environmental benefits. Despite the potential for environmental protection, several problems lead to low achievement of ITR's goals. Such problems include low revenue, the difficulty in inspecting declarations, obsolete productivity criteria, and intrinsic environmental distortions. In this work, we analyze current ITR and show that distortions can potentially occur even for properties that adopt deforestation in the Amazon. We also built a spatially explicit model that estimate tax revenue at a property level under different scenarios. Then, we simulate two scenarios: the first corresponds to the existing Law, and the second, to a legal revision we propose to overcome some of its current problems. We found that total tax collection under the current Law should be BRL 5.75 bi per year, almost four times the actual value collected in 2017 (BRL 1.5 bi). The results suggest that the low achievement of goals follows from a large group paying meager tax rates and another group being overpenalized. Results for the proposed revision highlight its inherent potential to address ITR's central challenges, and for a given set of parameters, the revenue under the new formulation could rise to BRL 16.8 bi per year. Our results provide a concrete and science-based alternative for ITR. The application of the proposals of revision we suggest could promote additional environmental protection, consequently strengthening the role of taxation as an instrument for the maintenance of natural vegetation in Brazil.
Purpose Papillary thyroid carcinoma (PTC) is the most common type of thyroid carcinoma and its incidence has greatly increased in the last 30 years. Ubiquitin-specific protease 13 (USP13) is a class of deubiquitinating enzymes (DUBs) and plays an important role in cellular functions such as cell cycle regulation, DNA damage repair, and different cell signaling pathways. Studies regarding the role of USP13 in cancer development and progression are divergent and there are no previous data regarding the role of USP13 gene in PTCs. In this study, we investigated the genetic cause of PTC diagnosed in multiple members of a Brazilian family. Methods Whole exome sequencing (WES) was performed to identify the genetic cause of PTC. Cycloheximide chase assay and clonogenic assay were performed to study USP13 stability and function in vitro. Results WES analysis identified a heterozygous missense variant c.1483G > A (p.V495M) in the USP13 gene that fully segregates with the disease. In silico modeling suggests that this variant may cause protein structural perturbations. USP13 overexpression increased the potential of a single cell to form colonies. The USP13 c.1483G > A variant enhanced the effects seen in USP13 overexpression and preserved protein stability for longer hours compared to the non-mutated USP13 protein. Conclusion Our study suggests that USP13 overexpression may play a role in tumorigenesis of PTCs; and that the USP13 p.V495M (c.1483G > A) variant enhances USP13 estability.
Introduction Home over center-based dialysis may minimize SARS-CoV2 exposure risks. We explored how the pandemic may have introduced challenges related to peritoneal dialysis (PD) supply availability, routine patient care, and how facility practices changed during this time. Methods The Peritoneal Dialysis/Dialysis Outcomes and Practice Patterns Study (PDOPPS/DOPPS) and International Society of Nephrology (ISN) administered a web-based survey (November 2020 – March 2021). Medical director responses were compared across 10 ISN regions. Results 165 PD facilities (51 countries) returned surveys. During the initial COVID-19 wave, the reported frequency of in-person patient visits decreased in 9 of 10 ISN regions. Before the pandemic, most facilities required a mask during PD exchanges which continued over the course of the pandemic. Although most facilities in different regions did not report PD supply disruptions, sites in Africa and South Asia reported major disruptions. Reductions in laparoscopic surgical procedures for PD catheters were reported by facilities in 9 out of 10 regions while non-surgical percutaneous procedures increased in facilities in 6 regions. Training of new PD patients declined in facilities in each region. Increased use of remote technology by patients to communicate with clinics was observed in all regions compared to pre-pandemic levels. Conclusion Marked within- and across-region variability was noted in PD facility burden, clinical practice, and adaptation to the COVID-19 pandemic. This study highlights opportunities to improve routine PD care, adapt to the ongoing pandemic, and increase preparedness for potential future interruptions in PD care.
Glioma 261 (Gl261) cell-mediated neurotoxicity has been reported in previous studies examining glioblastoma (GBM), and the effects of physical exercise (PE) on this neurotoxicity have been poorly investigated. This study aimed to evaluate the effects of a PE program in animals with experimental GBM. Male C57BL/6J mice were randomized into sham or GBM groups and subjected to a PE program for four weeks. Gl261 cells were administered into the intraventricular region at 48 h after the last exercise session. Body weight, water and feed consumption, and behavior were all evaluated for 21 days followed by euthanasia. The right parietal lobe was removed for the analysis of glial fibrillary acidic protein (GFAP), epidermal growth factor receptor (EGFR), vimentin, C-myc, nuclear factor kappa B (NF-κB), tumor necrosis factor-alpha (TNF-α), interleukin 1 beta (IL-1β), interleukin 6 (IL-6), hydrogen peroxide, the glutathione system, and oxidative damage to proteins. The results revealed changes in the behavioral patterns of the trained animals, and no anatomopathological changes were observed in response to PE training. In contrast, animals with GBM subjected to PE exhibited lower immunoexpression of c-MYC, vimentin, and GFAP. Although experimental GBM altered the redox profile and inflammatory mediators, no significant alterations were observed after PE. In conclusion, our data provide consistent evidence of the relationship between PE and the improvement of tumorigenic parameters against the neurotoxicity of GL261 cells.
Background: Type 2 Diabetes Mellitus (T2DM) patients are twice as likely to develop dementia. The study's goal was to evaluate cognitive performance and risk factors for cognitive decline in this population. Methods: Prospective observational study was conducted with 400 T2DM adults, of whom, during routine baseline and follow-up appointments, had socio-demographic, clinical, and laboratory data collected, and underwent physical examination, screening for depression symptoms (Patient Health Questionaire-9-PHQ-9), and cognitive tests: Mini-Mental State Examination (MMSE), Semantic Verbal Fluency Test, Trail Making Test A/B, and Word Memory Tests. Each cognitive test score was converted to a z-score and its average resulted in a new variable called Global Cognitive z-Score [GCS(z)]. Averages of the cognitive test scores and GCS(z) at both moments were compared by the Student's T-Test for paired samples. Multivariate binary logistic regression models were built to assess the association of GCS(z) < zero with risk factors for cognitive decline at the baseline and follow-up. Results: After exclusions, 251 patients were eligible, being 56.6% female, mean age of 61.1 (± 9.8) years, 12.6 (± 8.9) years of DM duration, and 7.6 (± 4.2) years of school education. Follow-up had 134 patients reevaluated and took place after a mean of 18.4(± 5.0) months. Eleven (14%) patients with a GCS(z) ≥ 0 at baseline turned into a GCS(z) < 0 at follow-up. There were no significant differences between the means of cognitive test scores and GCS(z) at the two evaluation moments. At the baseline, the multivariate logistic regression model identified five risk factors associated with GCS(z) < zero: age ≥ 65 years, schooling ≤ 6 years, arterial hypertension, depression symptoms, and diabetic retinopathy (DR), with odds ratio (OR) and 95% confidence interval (CI95%) respectively: 5.46 (2.42-12.34); 12.19 (5.62-26.46); 2.55 (0.88-7.39); 3.53 (1.55-8.07) e 2.50 (1.18-5.34). At follow-up, the risk factors for GCS(z) < zero were: schooling ≤ 6 years, DM duration ≥ 10 years, depression symptoms, arterial hypertension, and cardiovascular disease (CVD), OR and CI95% respectively: 10.15 (3.68-28.01); 2.68 (0.96-7.48); 4.92 (1.77-13.70); 7.21 (1.38-35.71) e 5.76 (1.93-17.18). Conclusions: Based on our results, cognitive evaluation and follow-up should be incorporated on the routine of T2DM patients, especially for those with advanced age, low education level, prolonged DM duration, arterial hypertension, depression symptoms, CVD, and DR.
Objetivo: analisar a aplicabilidade clínica das intervenções de enfermagem do subconjunto terminológico da Classificação Internacional para a Prática de Enfermagem (CIPE®) para assistência à mulher e à criança em processo de amamentação. Método: estudo transversal. Dados coletados pela observação, sistemática e não participativa, durante os cuidados às puérperas em uma maternidade. Participaram puérperas e seus recém-nascidos; enfermeiras e técnicos em enfermagem. Utilizado instrumento com as 213 intervenções do subconjunto. Resultados: em 15 observações, 24 intervenções foram prescritas e observadas, como examinar as mamas da mãe; 77 não prescritas e observadas, como estimular amamentação em livre demanda; e 112 não foram observadas e nem prescritas, como reforçar as vantagens da amamentação. Conclusão: as intervenções do subconjunto da CIPE® são aplicáveis em alojamento conjunto. Identificou-se deficiência na prescrição e avaliação das intervenções de enfermagem.
The global energy system is moving towards a sustainable future with new development strategies that reduce the carbon footprint, such as the water-energy-food (WEF) nexus. Several countries have implemented this link to provide energy and food security while maintaining the relationship between socioeconomic progress and environmental protection. The WEF nexus with energy development generates new interest in innovation, and it is important to explore the growth of this academic field. The work aims to analyse the scientific development of the WEF nexus during energy intervention processes, through bibliometric review models, for the knowledge of strategies in a bioenergy framework. The methodology consists of: (i) information compilation (Scopus and Web of Science) and software selection; (ii) information review on scientific production, author keywords and countries; and (iii) focus group analysis in a framework of energy development. The results show scientific interest from 2007, with exponential growth from 2016. The literature presents the interest of implementing the WEF nexus in energy processes to reduce environmental pollution, like ethanol in gasoline, biorefineries, sustainable agriculture, hydropower, and renewable energies (solar, wind). This scientific approach is dominated by the USA, China and the United Kingdom in environmental science, energy and engineering areas, accounting for 60% of the production. The study shows that the WEF nexus approach to energy developments creates new prospects for decision-making in socioeconomic , political, and environmental progress.
Objetivo: Demonstrar a associação entre doença de Alzheimer (DA) e o desenvolvimento de sarcopenia nos pacientes que foram diagnosticados com DA no ano de 2018 na Policlínica de Londrina. Método: Estudo de coorte retrospectivo com um número de 36 pacientes, os quais foram entrevistados presencialmente em 2019, quando realizaram o Mini-Exame do Estado Mental (MEEM); Atividades Básicas de Vida Diária (ABVD); SARC-F; IMC; medida da circunferência da panturrilha (CP); e, para aqueles suspeitos de sarcopenia, foram avaliados a medida de força de preensão palmar e o Timed Get Up and Go (Teste do sentar e levantar). Os resultados obtidos foram comparados aos de 2018 (ano do diagnóstico de DA). Resultados: Os pacientes diagnosticados com Doença de Alzheimer no ano de 2018 apresentaram um aumento na dependência para realização das ABVD (p = 0,049), uma diminuição do MEEM (p = 0,011), do IMC (p = 0,027) e do CP na avaliação de 2019, em relação ao ano anterior. Conclusão: A prevalência de sarcopenia em pacientes com DA foi de 34% após um ano de evolução da doença, ocasionando uma redução da qualidade de vida e aumento da necessidade de um cuidador para tarefas diárias simples.
Steels, titanium-, nickel-based superalloys, composites, and ceramics are materials commonly used in automotive, aerospace, mechanical engineering, and other industries. These materials have increased strength and heat-resistant properties, and that is why they are considered difficult to cut materials. These materials require particular approaches to advance the effectiveness of machining processes. This review article shows for the first time comprehensively of recent advanced efficient methods for enhancing the machining of hard-to-cut materials, namely for turning, milling, drilling, grinding, and other methods. Various methods of increasing the efficiency and machinability are considered, taking into account the thermal phenomena of the machining process and a directed change in temperature (decrease or increase) of individual sections of the surface of a tool or workpiece. The method of increasing tool life such as the use of new grades of tool materials and improvement of the design of the cutting tool, the use of various cooling methods, such as dry, conventional cooling system, high-pressure cooling (HPC), minimum quantity of lubricant (MQL), cryogenic lubrication (CL), improving the cutting tool wear resistance by hard coating, tool surface J o u r n a l P r e-p r o o f 2 texturing, implementation of machining methods, among them vibration-assisted machining, thermally assisted machining, hybrid machining process were considered in this work. The influence of these methods on cutting forces, surface roughness, chip morphology, tool life and wear mode, temperature, environmental influences are shown. In the end, this article shows the advantages and disadvantages of using various methods of increasing machining hard-to-cut materials and outlines the development prospects.
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2,785 members
Edvaldo Antonio Ribeiro Rosa
  • Xenobiotics Research Unit
Renata Ernlund Freitas Macedo
  • School of Life Sciences
Thiago Rocha da Cunha
  • Program in Bioethics
Gervasio Henrique Bechara
  • Graduate Program in Animal Science
Alex Antonio Ferraresi
  • Program in Cooperative Management (Head)
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