Comparative evaluation of surface quality, tool wear, and specific cutting energy for wiper and conventional carbide inserts in hard turning of aisi 4340 alloy steel

This paper presents an experimental study into the comparative response of wiper and round-nose conventional carbide inserts coated with TiCN + AL$_{2}$O$_{3}$ + TiN when turning an AISI 4340 steel alloy. The optimal process parameters, as identified by pre-experiments, were used for both types of inserts to determine the machined surface quality, tool wear, and specific cutting energy for different cutting lengths. The wiper inserts provided a substantial improvement in the attainable surface quality compared with the results obtained using conventional inserts under optimal cutting conditions for the entire range of the machined lengths. In addition, the conventional inserts showed a dramatic increase in roughness with an increased length of the cut, while the wiper inserts showed only a minor increase for the same length of cut. A scanning electron microscope was used to examine the wear for both types of inserts. Conventional inserts showed higher trends for both the average and maximum flank wear with cutting length compared to the wiper inserts, except for lengths of 200–400 mm, where conventional inserts showed less average flank wear. A higher accumulation of deposited chips was observed on the flank face of the wiper inserts than the conventional inserts. The experimental results demonstrated that edge chipping was the chief tool wear mechanism on the rake face for both types of insert, with more edge chipping observed in the case of the conventional inserts than the wiper inserts, with negligible evidence of crater wear in either case. The wiper inserts were shown to have a higher specific cutting energy than those detected with conventional inserts. This was attributed to (i) the irregular nose feature of the wiper inserts differing from the simpler round nose geometry of the conventional inserts and (ii) a higher tendency of chip accumulation on the wiper inserts

Parameters to Assess Nutritional Status in a Moroccan Hemodialysis Cohort

Introduction: Malnutrition is common in maintenance hemodialysis (HD) and is associated with increased mortality and morbidity in affected patients. The aim of this study was to determine the prevalence of malnutrition and correlate the methods of nutritional assessment.Methods: We evaluated the nutritional status of 40 prevalent HD patients by subjective global assessment (SGA) score, anthropometrics [body mass index (BMI), arm circumference (AC), triceps skin-fold thicknesses (TSF), arm muscle circumference (AMC)], biochemical tests [normalized protein equivalent to total nitrogen appearance (nPNA), and pre-dialysis serum albumin and serum prealbumin levels] and bio-electrical impedance (BEI) analysis to estimate body composition [lean tissue index (LTI) and fat tissue index (FTI)].Results: The study assessed 40 patients (20 males and 20 females) with a mean age of 50.7±16.5 years. The prevalence of malnutrition according to the different methods ranged from 5 % to 65%. There were highly significant gender-specific differences in AMC (p < 0.001) and TSF (p < 0.001). The BEI revealed a highly significant difference in LTI (p < 0.001) but no difference in FTI (p = 0.14) according to gender. There was a positive correlation between LTI and both serum albumin (r = 0.37; p = 0.018) and serum prealbumin (r = 0.53; p < 0.001). Also, there was a significant positive correlation between FTI and BMI (r = 0.59; p < 0.001), AC (r = 0.44; p = 0.004) and TSF (r = 0.61; p < 0.001).Conclusion: Our data suggest that BEI analysis provides a useful means of assessing nutritional status and was correlated with anthropometrics and biochemical findings.Keywords: Anthropometric Measurements; Bioelectrical Impedance; Hemodialysis; Malnutrition; Subjective Global Assessmen

Physical Activity Recognition Based on a Parallel Approach for an Ensemble of Machine Learning and Deep Learning Classifiers

Human activity recognition (HAR) by wearable sensor devices embedded in the Internet of things (IOT) can play a significant role in remote health monitoring and emergency notification, to provide healthcare of higher standards. The purpose of this study is to investigate a human activity recognition method of accrued decision accuracy and speed of execution to be applicable in healthcare. This method classifies wearable sensor acceleration time series data of human movement using efficient classifier combination of feature engineering-based and feature learning-based data representation. Leave-one-subject-out cross-validation of the method with data acquired from 44 subjects wearing a single waist-worn accelerometer on a smart textile, and engaged in a variety of 10 activities, yields an average recognition rate of 90%, performing significantly better than individual classifiers. The method easily accommodates functional and computational parallelization to bring execution time significantly down

Fracture Process in ± θ Laminates Subjected to Mode II Loading

This work studies the behavior of a multidirectional laminate under Mode II loading. We describe the process of delamination in a reinforced composite of glass/epoxy. The stacking sequence (plies orientation [±θ]) was selected to minimize the coupling effects. The Mode II interlaminar test under three-point bending and cantilever flexure using ENF (End Notch Flexure) and ELS (End Load Split) specimens, respectively, was performed and analyzed. The test procedures and the results of strain-energy-release rate study for crack initiation are presented. The fracture process and the mechanical behavior of the two types of specimens are analyzed. The analysis clearly shows a close link between the angle θ, the ratio a/L, and the thickness h of the specimen. Fracture by delamination can be obtained only with an optimal choice of these parameters. The analysis of the states of stresses at the tip of crack allows us to explain the phenomenon of bifurcation between plies and is confirmed by the experimental results.Исследуется поведение многомерного ламината при его нагружении по типу KII . Описан процесс деламинирования упрочненного стеклоэпоксидного композита. Для минимизации эффектов трения выбрана ориентация ± θ. Рассмотрена методика межламинарных испытаний по типу KII с использованием схем трехточечного и консольного изгиба соответственно образцов типа ENF (торцевое защемление с консольным изгибом нагрузкой, равномерно распределенной по ширине свободного торца) и ELS (шарнирно закрепленная балка с центральной нагрузкой, равномерно распределенной по ширине балки). Представлены экспериментальные методики и результаты исследования скоростей высвобождения энергии деформации при инициировании трещин. Для двух вышеуказанных типов образцов проанализирован процесс разрушения и механического поведения материала. Установлена тесная корреляционная связь между величинами угла θ, соотношением a/L и толщиной образцов h. Показано, что разрушение вследствие деламинации возможно только при условии оптимального выбора этих параметров. Анализ напряженного состояния в вершине трещины позволяет объяснить явление межслойной бифуркации, его результаты хорошо согласуются с экспериментальными данными.Досліджується поведінка багатовимірного ламіната при його навантаженні за типом KII . Описано процес деламінування зміцненого склоепоксидного композита. Для мінімізації ефектів тертя вибрано орієнтацію ± θ. Розглянуто методику міжламінарних випробувань за типом KII із використанням схем триточкового і консольного згину відповідно зразків типу ENF (торцеве затиснення з консольним згином навантаженням, що рівномірно розподілене по ширині вільного торця) і ELS (шарнірно закріплена балка з центральним навантаженням, що рівномірно розподілене по ширині балкі). Представлено експериментальні методики і результати щодо швидкостей звільнення енергії деформації при ініціюванні тріщин. Для двох вищевказаних типів зразків проаналізовано процес руйнування і механічної проведінки матеріалу. Установлено кореляційний зв’язок між величинами кута θ, відношенням a /L і товщиною зразків h. Показано, що руйнування внаслідок деламінації можливе лише за умови оптимального вибору цих параметрів. Аналіз напруженого стану у вістрі тріщини дозволяє пояснити явище міжшарової біфуркації і добре узгоджується із експериментальними даними

Bronchodilation induced by PGE2 is impaired in Group-III pulmonary hypertension

BACKGROUND AND PURPOSE: In patients with pulmonary hypertension (PH) associated with lung disease and/or hypoxia (Group III), a reduction of pulmonary vascular tone and tissue hypoxia are considered therapeutically beneficial. Prostaglandin (PG) E2 and PGI2 induce potent relaxation of human bronchi from non-PH (control) patients via EP4 and IP receptors, respectively. However, the effects of PGE2 /PGI2 and their mimetics on human bronchi from PH-patients are unknown. Our aim was to compare the relaxant effects of several PGI2 -mimetics approved for treating PH-Group I with several PGE2 -mimetics in bronchial preparations derived from PH-Group III and control patients. EXPERIMENTAL APPROACH: Using an organ bath system, the tone of bronchial muscle was investigated in tissue from either control or PH-Group III patients. Expression of prostanoid receptors were analyzed by Western blot and real-time PCR and endogenous PGE2 , PGI2 and cAMP levels were determined by ELISA. KEY RESULTS: Maximal relaxations induced by different EP4 agonists (PGE2 , L-902688, ONO-AE1-329) were significantly decreased in human bronchi from PH-patients versus controls. In contrast, the maximal relaxations produced by PGI2 -mimetics (iloprost, treprostinil, beraprost) were similar for both groups of patients. Both EP4 and IP receptor protein and mRNA expressions were significantly lower in human bronchi from PH-patients. cAMP levels significantly correlated with PGI2 but not with PGE2 levels. CONCLUSION AND IMPLICATIONS: This study shows that PGI2 -mimetics have preserved maximal bronchodilation in PH-Group III patients. The decreased bronchodilation induced by EP4 agonists suggests that restoration of EP4 expression in airways of PH-patients with respiratory diseases could bring additional therapeutic benefit

Mathematical modeling and design of layer crystallization in a concentric annulus with and without recirculation

A solution layer crystallization process in a concentric annulus is presented that removes the need for filtration. A dynamic model for layer crystallization with and without a recirculation loop is developed in the form of coupled partial differential equations describing the effects of mass transfer, heat transfer, and crystallization kinetics. The model predicts the variation of the temperature, concentration, and dynamic crystal thickness along the pipe length, and the concentration and temperature along the pipe radius. The model predictions are shown to closely track experimental data that were not used in the model's construction, and also compared to an analytical solution that can be used for quickly obtaining rough estimates when there is no recirculation loop. The model can be used to optimize product yield and crystal layer thickness uniformity, with constraints on the supersaturation to avoid bulk nucleation by adjusting cooling temperatures in the core and jacket. © 2013 American Institute of Chemical Engineers

The accumulation of assembly intermediates of the mitochondrial complex I matrix arm is reduced by limiting glucose uptake in a neuronal-like model of MELAS syndrome

Ketogenic diet (KD) which combined carbohydrate restriction and the addition of ketone bodies has emerged as an alternative metabolic intervention used as an anticonvulsant therapy or to treat different types of neurological or mitochondrial disorders including MELAS syndrome. MELAS syndrome is a severe mitochondrial disease mainly due to the m.3243A > G mitochondrial DNA mutation. The broad success of KD is due to multiple beneficial mechanisms with distinct effects of very low carbohydrates and ketones. To evaluate the metabolic part of carbohydrate restriction, transmitochondrial neuronal-like cybrid cells carrying the m.3243A > G mutation, shown to be associated with a severe complex I deficiency was exposed during 3 weeks to glucose restriction. Mitochondrial enzyme defects were combined with an accumulation of complex I (CI) matrix intermediates in the untreated mutant cells, leading to a drastic reduction in CI driven respiration. The severe reduction of CI was also paralleled in post-mortem brain tissue of a MELAS patient carrying high mutant load. Importantly, lowering significantly glucose concentration in cell culture improved CI assembly with a significant reduction of matrix assembly intermediates and respiration capacities were restored in a sequential manner. In addition, OXPHOS protein expression and mitochondrial DNA copy number were significantly increased in mutant cells exposed to glucose restriction. The accumulation of CI matrix intermediates appeared as a hallmark of MELAS pathophysiology highlighting a critical pathophysiological mechanism involving CI disassembly, which can be alleviated by lowering glucose fuelling and the induction of mitochondrial biogenesis, emphasizing the usefulness of metabolic interventions in MELAS syndrome

Mathematical modeling and design of layer crystallization in a concentric annulus with and without recirculation [Abstract]

Mathematical modeling and design of layer crystallization in a concentric annulus with and without recirculation [Abstract

Prostanoid EP₂ Receptors Are Up-Regulated in Human Pulmonary Arterial Hypertension: A Key Anti-Proliferative Target for Treprostinil in Smooth Muscle Cells

Prostacyclins are extensively used to treat pulmonary arterial hypertension (PAH), a life-threatening disease involving the progressive thickening of small pulmonary arteries. Although these agents are considered to act therapeutically via the prostanoid IP receptor, treprostinil is the only prostacyclin mimetic that potently binds to the prostanoid EP₂ receptor, the role of which is unknown in PAH. We hypothesised that EP₂ receptors contribute to the anti-proliferative effects of treprostinil in human pulmonary arterial smooth muscle cells (PASMCs), contrasting with selexipag, a non-prostanoid selective IP agonist. Human PASMCs from PAH patients were used to assess prostanoid receptor expression, cell proliferation, and cyclic adenosine monophosphate (cAMP) levels following the addition of agonists, antagonists or EP₂ receptor small interfering RNAs (siRNAs). Immunohistochemical staining was performed in lung sections from control and PAH patients. We demonstrate using selective IP (RO1138452) and EP₂ (PF-04418948) antagonists that the anti-proliferative actions of treprostinil depend largely on EP₂ receptors rather than IP receptors, unlike MRE-269 (selexipag-active metabolite). Likewise, EP₂ receptor knockdown selectively reduced the functional responses to treprostinil but not MRE-269. Furthermore, EP₂ receptor levels were enhanced in human PASMCs and in lung sections from PAH patients compared to controls. Thus, EP₂ receptors represent a novel therapeutic target for treprostinil, highlighting key pharmacological differences between prostacyclin mimetics used in PAH