The influence of laser power and scan speed on the dimensional accuracy of Ti6Al4V thin-walled parts manufactured by selective laser melting

Laser Powder Bed Fusion (LPBF) technologies such as Selective Laser Melting (SLM) are being increasingly considered as viable production routes. This paradigm change demands an in-depth understanding of the fabrication process and variables, as previous studies have shown that energy density calculation alone is insufficient, because parts fabricated using similar energy density, but using different combinations of parameters, can display significantly different properties and dimensions. Thin-walled parts are particularly influenced by processing parameters; in this sense, this study explores the influence of laser power and scan speed on the dimensions of Ti6Al4V thin-walled tubes. Predictive models for manufacturing Ti6Al4V thin-walled tubes were developed using Response Surface Methodology (RSM), and the most influential (single and combined) factors were determined using Analysis of Variance (ANOVA). Three models were obtained: for the wall melt zone thickness, the total wall thickness, and the hole width.FCT (Fundação para a Ciência e a Tecnologia) through the project PTDC/EME-EME/1442/2020 (Add2MechBio) and POCI-01-0247-FEDER-024533 (Add-Additive–Add additive manufacturing to Portuguese industry). Acknowledgments to the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020, and LA/P/0006/2020, financed by national funds through the FCT/MEC (PIDDAC)

Selective laser melting of Ti6Al4V sub-millimetric cellular structures: prediction of dimensional deviations and mechanical performance

Ti6Al4V sub-millimetric cellular structures arise as promising solutions concerning the progress of conventional orthopedic implants due to its ability to address a combination of mechanical, physical and topological properties. Such ability can improve the interaction between implant materials and surrounding bone leading to longterm successful orthopedic implants. Selective Laser Melting (SLM) capability to produce high quality Ti6Al4V porous implants is in great demand towards orthopedic biomaterials. In this study, Ti6Al4V cellular structures were designed, modeled, SLM produced and characterized targeting orthopedic implants. For that purpose, a set of tools is proposed to overcome SLM limited accuracy to produce porous biomaterials with desired dimensions and mechanical properties. Morphological analyses were performed to evaluate the dimensional deviations noticed between the model CAD and the SLM produced structures. Tensile tests were carried out to estimate the elastic modulus of the Ti6Al4V cellular structures. The present work proposes a design methodology showing the linear correlations found for the dimensions, the porosity and the elastic modulus when comparing the model CAD designs with Ti6Al4V structures by SLM.This work was supported by FCT through the grant SFRH/BD/ 128657/2017 and the projects PTDC/EMS-TEC/5422/2014_ADAPT PROSTHESIS, NORTE-01-0145-FEDER-000018 – HAMaBICo and UID/ EEA/04436/2019

Força, qualidade muscular e marcadores de risco cardiometabólico em mulheres idosas

O processo de envelhecimento está associado a um declínio nas funções fisiológicas, refletindo em reduções na qualidade muscular, bem como em alterações de marcadores de risco cardiometabólico. Nesse sentido, o objetivo do estudo foi verificar a associação entre qualidade muscular e marcadores de risco cardiometabólico em mulheres idosas. Trinta mulheres idosas (66,13±5,26 anos, 67,33±12,45 kg, 1,54±0,07 m, 28,20±4,72 IMC) foram submetidas à avaliação da espessura e força musculares do quadríceps, e à análise sanguínea de marcadores de risco cardiometabólico (glicemia, insulina basal, proteína C-reativa, colesterol total, HDL-colesterol, LDL-colesterol, VLDL-colesterol, triglicerídeos, e índice HOMA-IR). Não foram encontradas correlações significativas entre os fenótipos musculares e os marcadores de risco cardiometabólico estudados, mesmo com controle para fatores de confusão. A presente pesquisa indica não haver correlação entre força e qualidade muscular com os marcadores de risco cardiometabólico estudados.The aging process is associated with a decline in physiological functions, including a reduction in muscle quality, as well as changes in cardiometabolic risk factors. Thus, the aim of this study was to verify if a correlation exists between muscle strength and quality and cardiometabolic risk markers in older women. Thirty older women (66.13±5.26 years, 67.33±12.45 kg, 1.54±0.07 m, body mass index: 28.20±4.72) were submitted to the evaluation of muscle thickness and strength and blood analysis of cardiometabolic risk markers (glucose, basal insulin, C-reactive protein, total cholesterol, HDL-cholesterol, LDL-cholesterol, VLDL-cholesterol, triglycerides, and HOMA-IR). No significant correlations were found between muscle phenotypes and markers of cardiometabolic risk, even after adjustment for confounding factors. The present study indicates that muscle strength or quality is not correlated with markers of cardiometabolic risk

ESPÉCIES ARBÓREAS DA ARBORIZAÇÃO URBANA DO CENTRO DO MUNICÍPIO DE CAMPO GRANDE, MATO GROSSO DO SUL, BRASIL

As árvores constituem uma parte viva de qualquer cidade, sem as quais o ambiente urbano perderia em agradabilidade, influenciando no clima local, na qualidade do ar e na fauna, principalmente de aves além do fator estético. Este estudo teve por objetivos efetuar o levantamento das espécies arbóreas empregadas no paisagismo urbano do centro do município de Campo Grande, Mato Grosso do Sul, Brasil. Para tanto, foi efetuada a coleta de ramos dos exemplares, que posteriormente foram herborizados e identificados com o auxílio de chaves de identificação, literatura pertinente e comparação com material do Herbário CGMS. Foram identificadas 28 famílias, 52 gêneros e 61 espécies, das quais 30 são nativas do Brasil. A família com maior número de espécies foi Leguminosae (11 espécies), seguida de Bignoniaceae (6), Moraceae (5) e Myrtaceae (5), e os gêneros mais representativos foram Ficus (5) e Handroanthus (3). As espécies mais comumente observadas foram Bauhinia variegata L., Caesalpinia peltophoroides Benth., Ficus benjamina L., Inga laurina (Sw.) Willd., Lagerstroemia indica L. e Licania tomentosa (Benth.) Fritsch

Clinical correlates of high burden of general medical comorbidities in patients with bipolar disorder

Background: Bipolar disorder is associated with an increased burden of general medical conditions that might be related to a more severe illness course. Methods: This is a cross-sectional study that evaluated clinical correlates of general medical comorbidities in outpatients with bipolar disorder (BD) involving 203 adult patients with a DSM-IV diagnosis of BD, consecutively recruited from the Bipolar Research Program (PROTAHBI) in Porto Alegre, Brazil. Clinical, demographic and anthropometrical variables were systematically assessed, and general medical comorbidity was measured using the Cumulative Illness Rating Scale (CIRS). Results: The prevalence of one or more medical comorbidities was 90.1%. The most common were those from endocrine/metabolic/breast, neurologic and vascular categories. A high burden of general medical comorbidities (defined as CIRS total score ≥ 4) was related to increasing age and body mass index and longer duration of illness after controlling for confounding factors. Limitations: The cross-sectional design limits our ability to make causal conclusions. Also, our sample consisted of patients with longer illness duration from a tertiary clinic and may not generalize to the whole spectrum of bipolar disorder. Conclusions: BD was associated with a high burden of general medical conditions related to age, obesity and longer duration of illness. Medical comorbidities must be incorporated as a core feature in the development of effective treatment strategies for bipolar disorder

Macroscopic Anatomy, Histopathology, and Image Diagnosis of Joints and Synovial Cartilages

Joints are physiological connections formed by the association of two or more bones that confer mobility to the skeleton of vertebrates. Composed of several structures, these are often related to pathologies of varied origins, which determine symptomatology of varying degrees of intensity and impairment, responsible for the decrease in life expectancy and the well-being of affected populations. Most of the time, the treatment for these diseases is only symptomatic, aiming at the relief of pain and the return of the patient to daily activities. Thus, there has been an increasing interest in the search for new knowledge about the mechanisms that lead to joint disorders and effective therapeutic resources that may contribute to the fight against pain and to the definitive treatment of joint dysfunctions. To this aim, the knowledge of diagnostic methods, especially imaging methods, is of fundamental importance for the recognition of articular affections, enabling a targeted and effective treatment. Among these auxiliary exams currently used to evaluate the joints, the noninvasive ones are the first choice, where radiography, ultrasonography, magnetic resonance imaging (MRI), computed tomography, and arthroscopy are inserted

Standard Electrocardiographic Data of Peccaries (Tayassu tajacu)

Background:Peccaries (Tayassu tajacu, Linnaeus, 1758) are wild suiformes that belong to the Tayassuidae family. Electrocardiography is an important technique for cardiovascular evaluation. Analysis of various intervals, segments, complexes and waveforms of electrocardiographic (ECG) traces aids in the diagnosis of cardiac alterations and in the differentiation of congenital and acquired heart diseases from physiological cases. However, in wild animal medicine, the various patterns of normality and the evaluation of electrical traces associated with heart disease have not yet been sufficiently elucidated. The purpose of this study was to characterize the electrocardiographic (ECG) traces of peccaries sedated using ketamine and xylazine.Materials, Methods & Results:Fourteen healthy adult animals that were subjected to digital ECG examination were used. Animals with evidence of systemic diseases, cardiovascular abnormalities (murmurs or arrhythmias), or any degree of valve insufficiency observed on echocardiogram and animals that exhibited excessive stress during the examination were excluded from the study. All animals presented with a normal sinus rhythm. A combination of 15 mg/kg of ketamine hydrochloride and 3 mg/kg of midazolam maleate was applied intramuscularly for chemical immobilization. The animals were manipulated after 15 min, when the onset of the anaesthetic effect was verified, for a duration of 45 min, and no reinforcement dose was necessary to complete the electrocardiographic examination.  No significant differences were observed in the P-wave duration, PR interval and QT interval between genders (P > 0.05). No significant differences were found between the amplitudes of the P and R waves between males and females (P > 0.05). The observed P waves were small, monophasic and positive. The QRS complex was positive in the DI, DII, DIII, aVF, V4 and V10 derivations and negative in the aVR, aVL, V1 and V2 derivations. In 71% of the animals, the T wave showed negative polarity in the DI, DII, DIII, aVL, aVF, and V10 derivations and positive polarity in the aVR, V1, V2 and V4 derivations. The ST segment was isoelectric in 100% of the animals. GraphPad Prism 7 (La Jolla, CA, USA) software was used to analyze the data, with non-parametric tests used to test for differences in the variables between the sexes. In these tests, a P-value of 0.05 was considered to indicate statistical significance.Discussion:Although studies on the cardiac electrophysiology of wild animals have previously shown good results for several species, this is the first study concerning the standardization ECG traces for peccaries. However, due to the wild nature of these animals, their manipulation for handling and data collection purposes is only feasible under chemical containment, although other studies have used non-anaesthetized agoutis. It is not known to what extent these results may have been influenced by the effects of stress. Drugs used for this function may have direct effects on cardiac function. Therefore, the presumed normal ECG values, as well as the recognition of changes due to drug or iatrogenic interactions, are of fundamental importance.  This protocol provided high-quality anaesthetized peccary ECG traces, allowing reliable measurements of waves and intervals and assessment of the cardiac rhythm and heart rate. The surface registry digital ECG recording technique used with chemical containment allowed good monitoring and rapid acquisition and was well tolerated by the animals. 

Ocular Echobiometry and Resistivity Index of External Ophthalmic Artery in Agoutis (Dasyprocta prymnolopha)

Background: Veterinary Ophthalmology provides complementary information for the diagnosis of ocular pathologies. Studies in wild species are essential. Among the diagnostic techniques in ophthalmology, two-dimensional ultrasonography stands out. The agouti is a rodent belonging to the Dasyproctidae family that has been widely used as an experimental model. For these animals, sight is one of the crucial senses for their survival. The aim of this study was to evaluate the effectiveness of the two-dimensional ocular ultrasound technique to obtain anatomical measurements and the external ophthalmic artery resistivity index, presumably normal in the species Dasyprocta prymnolopha.Materials, Methods & Results: Forty eye bulbs of 20 adult rodents of the species were evaluated by ultrasonography. In these animals, B-mode echobiometry was performed using the transpalpebral approach and the hemodynamic study of the external ophthalmic artery using the color Doppler technique. All examinations were initiated by the left eye bulb and all measurements were performed by only one examiner. The collected data related to echobiometry were analyzed using Bioest 5.0 for Windows. Initially, normality was tested using the Shapiro-Wilk test for each parameter, then the paired t-test was performed, comparing right and left eyes, and a significance level of 5% (P < 0.05) was adopted. Based on the methodology used, the following values were obtained for the right and left eyeballs, respectively: anterior chamber thickness - mean of 1.28 ± 0.3 mm and 1.22 ± 0.1 mm; lens thickness - 8.27 ± 0.9 mm and 8.11 ± 0.9 mm; vitreous chamber thickness - 5.35 ± 0.48 mm and 5.30 ± 0.47 mm and axial length - 12.7 ± 0.9 mm and 13 ± 0.68 mm. The mean external ophthalmic artery resistivity values were 0.4305 ± 0.0390 and 0.4258 ± 0.0387 (right and left eye, respectively), characterizing a low resistance. There was no statistical difference between the right and left eyeballs in any of the studied parameters.Discussion: The use of the convex transducer was feasible, promoting adequate contact with the ocular surface and images of satisfactory quality for obtaining measurements, similar to what was observed in studies evaluating the ocular biometry of primates and dogs. The anterior chamber thickness values in this experiment did not differ statistically between the antimers, as well as observed for dogs. The data obtained for lens thickness did not differ statistically for antimers, like those obtained for other rodent species evaluated with the same methodology. The mean values of vitreous chamber thickness were like those observed in chinchillas but correspond to about half of that obtained for capybaras. In this study, the external ophthalmic artery was characterized in all animals, but obtaining the spectral tracing was difficult due to its fine caliber. In wild animals, and especially in wild rodents, there are few data reporting the resistivity of the ophthalmic artery, and there is a lack of studies, which can be explained by the behavioral characteristics of defense and by the high susceptibility to stress in capture, since the performing the technique requires, as in other procedures, the use of chemical containment.Keywords: Doppler flow, ultrasound, eye, agouti

Presumed Normal Hemodynamic Values of the Arteries in the Final Third Period of Gestation in Bitches

Background: Doppler ultrasonography enables the investigation of vascular blood flow indexes in gestational assessment, being able to detect vascular resistances that can affect fetal and maternal circulation, such as cases of placental insufficiency, associated with fetal cerebral oxygenation deficit and fetal distress. The study aims to assume hemodynamically normal values in the final third of gestation in bitches, of the umbilical, uteroplacental, middle cerebral and internal carotid arteries, correlating the obtained Doppler velocimetric indexes, for the assessment of the feto-placental circulation, and prediction of fetal viability indexes, fetal centralization and probable date of delivery.Materials, Methods & Results: Thirty healthy bitches were examined in the final third of gestation (40-60 days). These were evaluated by Doppler ultrasonography at 2 times (T): T1: between 40-50 days; T2: between 51-60 of gestation. At each time point, the peak systolic velocities (PSV) and end-diastolic velocities (EDV) used to obtain the pulsatility (IP) and resistivity (IR) indexes of the umbilical, uteroplacental, middle cerebral and internal carotid arteries of fetuses were evaluated. Also, the systole/diastole (S/D) ratio of these vessels was evaluated. The data obtained were subjected to analysis of variance and Tukey test, using a P value equal to 5%. A significant difference was observed between velocities and Doppler velocimetric indexes between the 2 phases of the gestational final third in all studied vessels. There was an increase in the values of PSV and EDV and a decrease in the indexes, as the probable date of delivery approached. The analysis of the umbilical cord IR showed an increase from P1 to P2 (P < 0.05), while the IP decreased at the same time. For all studied variables there was a statistically significant difference (P < 0.05). In the uteroplacental artery, similarly to the umbilical artery, the PSV and EDV values showed an increase between P1 and P2, while the S/D ratio decreased up to 60 days of gestation (P2). The IR and IP of these vessels decreased during the study interval in pregnant bitches. The studied variables showed a statistically significant difference when analyzed comparatively between P1 and P2 (P < 0.05). As for the middle cerebral artery and internal carotid artery, the PSV and EDV values increased until the end of pregnancy. Likewise, the Doppler velocimetric values and the S/D ratio decreased until the end of pregnancy (P2).Discussion: The hemodynamic values obtained for the umbilical artery and uterine artery were significantly different between 40 and 50 days of gestation (P1) and 50 and 60 days of gestation (P2), with a decrease in vascular resistance and an increase in velocities. It can be related to a greater association of maternal-fetal blood perfusion, due to the increased demand for the development of the fetus. The Middle Cerebral Artery (MCA) also showed changes between P1 and P2, with an increase in PSV and EDV in the final third of pregnancy, and the S/D ratio was reduced, differing significantly between P1 and P2. The systolic (PSV) and diastolic (EDV) flow velocities of the internal carotid artery increased progressively, while the IR, IP and the S/D ratio decreased, between the evaluated periods (P1 and P2), providing greater flow in canine fetuses, maintaining normal heart rate, indicating positive fetal viability. Keywords: Doppler, gestational ultrasound, bitches, fetal circulation, umbilical artery, internal carotid, fetal middle cerebral artery