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Open access

Xue Peng, Can Wei, Hong-Zhu Li, Hong-Xia Li, Shu-Zhi Bai, Li-Na Wang, Yu-Hui Xi, Jin Yan and Chang-Qing Xu

Abstract

Background and Objectives

Calcium-sensing receptor (CaSR) is known to regulate hypoxia-induced pulmonary hypertension (HPH) and vascular remodeling via the phenotypic modulation of pulmonary arterial smooth muscle cells (PASMCs) in small pulmonary arteries. Moreover, autophagy is an essential modulator of VSMC phenotype. But it is not clear whether CaSR can regulate autophagy involving the phenotypic modulation under hypoxia.

Methods

The viability of human PASMCs was detected by cell cycle and BrdU. The expressions of proliferation protein, phenotypic marker protein, and autophagy protein in human PASMCs were determined by western blot.

Results

Our results showed that hypoxia-induced autophagy was considerable at 24 h. The addition of NPS2390 decreased the expression of autophagy protein and synthetic phenotype marker protein osteopontin and increased the expression of contractile phenotype marker protein SMA-ɑ and calponin via suppressing downstream PI3K/Akt/mTOR signal pathways.

Conclusions

Our study demonstrates that treatment of NPS2390 was conducive to inhibit the proliferation and reverse phenotypic modulation of PASMCs by regulating autophagy levels.

Open access

Chuan Li, Lili Qu, Cullen Farragher, Anthony Vella and Beiyan Zhou

Open access

Gianluca Rigatelli, Marco Zuin, Tra T. Ngo, Hung T. Nguyen, Aravinda Nanjundappa, Ernest Talarico, Le Cao Phuong Duy and Thach Nguyen

Abstract

Background and Objectives

Significant rather than moderate coronary artery stenosis has been postulated to be the main substrate of plaque rupture in acute myocardial infarction (AMI). We evaluate if cavitation could influence the coronary artery plaque rupture contributing to the progression of thrombotic process.

Methods

We reconstructed a 3D model of the left anterior descending coronary artery (LAD) after reviewing the intravascular ultrasound (IVUS) data of 30 consecutive patients with mild to severe coronary artery disease.

Results

Turbulent flow or cavitation occurs in both concentric and eccentric coronary artery stenosis (≥ 75% for the former and ≥ 50% for the latter). The analysis of vapor phase demonstrated that cavitation propagated downstream, creating microbubbles, which exploded when the fluid pressure was lower than the vapor pressure at a local thermodynamic state. The relative higher vorticity magnitude (as turbulent flow in vivo angiogram) observed on the distal cap of the atherosclerotic plaque created a higher turbulence, probably able to destabilize the plaque through a micro-erosion process.

Conclusions

Cavitation seems to be able to promote the thrombotic occlusion within the coronary vessels due the ‘constant injuries’ created by the micro-explosion of bubbles.

Open access

Sebastien Redant, Hamda Hussein, Aude Mugisha, Rachid Attou, David De Bels, Patrick M. Honore and Corinne C. De Laet

Open access

Abdelhak Elhannani, Kaddour Refassi, Abbes Elmeiche and Mohamed Bouamama

Abstract

This investigation deals with the vibration analysis of a rotating tapered shaft in Functionally Graded Material (FGM). The dynamic system is modeled using the Timoshenko beam theory (FSDBT) with consideration of gyroscopic effect and rotary inertia. The equations of motion are expressed by the hierarchical finite element method based on bi-articulated boundary conditions. The material properties are continuously varied in the thickness direction of a hollow shaft according to the exponential law function (E-FGM). The presented model is validated by comparing the numerical results found with the available literature. Various analyses are carried out to determine the influence of taper angle and material distribution of the two extreme materials on the dynamic behavior of FGM conical rotors system.

Open access

Milon Selvam Dennison, Sivaram N M, Debabrata Barik and Senthil Ponnusamy

Abstract

The objective of this study is to analyse the effect of tool-work interface temperature observed during the turning of AISI 4340 cylindrical steel components in three machining conditions, namely flooded, near-dry and dry conditions with three separate CNMG-PEF 800 diamond finish Titanium Nitride (TiN) coated carbide cutting tool. The machining parameters considered in this study are cutting velocity, feed rate and depth of cut. The experiments were planned based on full factorial design (33) and executed in an All Geared Conventional Lathe. The tool-work interface temperature was observed using a K-type tool-work thermocouple, while the machining of steel, and subsequently, a mathematical model was developed for the tool-work interface temperature values through regression analysis. The significance of the selected machining parameters and their levels on tool-work interface temperature was found using analysis of variance (ANOVA) and F-test. The results revealed that machining under near-dry condition exhibited lesser temperature at the tool-work interface, which is the sign of producing better quality products in equivalence with the machining under flooded condition.

Open access

S. Sakthivelu, M. Meignanamoorthy, M. Ravichandran and P. P. Sethusundaram

Abstract

This research made an attempt to synthesize aluminum metal matrix composites through stir casting technique. The matrix material chosen in this study was AA7050 and the reinforcement material was ZrSiO4. The composites AA7050, AA7050-10%ZrSiO4, and AA7050-15%ZrSiO4 were used. The wear behavior of the aluminum matrix composites was investigated by using pin-on-disc tribometer. The advanced material has substantial development in tribological behavior when the reinforcement percentage is increased. From the experimental results, it was confirmed that sliding distance of 1200 m, applied load of 3 N and sliding speed of 2 m/s result in minimum wear loss and coefficient of friction, while adding 10%ZrSiO4 to the AA7050.

Open access

Praveen Ailawalia and Amit Singla

Abstract

The present investigation deals with the twodimensional deformation because of laser pulse heating in a thermoelastic microelongated layer with a thickness of 2d, which is immersed in an infinite nonviscous fluid. Normal mode analysis technique is applied to obtain the analytic expressions for displacement component, force stress, temperature distribution, and microelongation. The effect of elongation and laser pulse rise time on the derived components have been depicted graphically.

Open access

N. Manopradha, S. Rama, S. Gowri, K. Kirubavathi and K. Selvaraju

Abstract

This work illustrates the significance of kinetic parameters of nucleation and thermal decomposition for Pyridine-2-carboxylic acid crystals. In the interest of maximizing the growth condition for the production of single crystals, nucleation parameters such as interfacial energy (σ), volume free energy (ΔGv), critical energy barrier for nucleation (ΔG *), radius of the critical nucleus (r*) and nucleation rate (J) were determined from the classical nucleation theory of solubility-enthalpy relation. The optimized geometry of the compound was computed from the DFT-B3LYP gradient calculations employing 6-31G(d,p) basis set and its vibrational frequencies were evaluated. Based on the vibrational analysis, the thermodynamic parameters were obtained and the correlative equations between these thermodynamic properties and variation in temperatures were also reported.