Role of Cyclooxygenase-2 in Head and Neck Tumorigenesis

The cyclooxygenase-2 (COX-2) is a potent enzyme that converts arachidonic acid to prostaglandins (PG), including PGE2, a key mediator of inflammation and angiogenesis. Importantly, COX-2 is activated in response to inflammatory stimuli, where it is also believed to promote the development and progression of head and neck cancers (HNC). COX-2 can mediate its protumorigenic effect through various mechanisms, such as inducing cell proliferation, inhibition of apoptosis, and suppressing the host’s immune response. Furthermore, COX-2 can induce the production of vascular endothelial growth factors, hence, promoting angiogenesis. Indeed, the ability of COX-2 inhibitors to selectively restrict the proliferation of tumor cells and mediating apoptosis provides promising therapeutic targets for cancer patients. Thus, in this comprehensive review, we summarized the reported differential expression patterns of COX-2 in different stages of head and neck carcinogenesis—from potentially premalignant lesions to invasive carcinomas. Furthermore, we examined the available meta-analysis evidence for COX-2 role in the carcinogenesis of HNC. Finally, further understanding of the biological processes of COX-2 and its role in orchestrating cell proliferation, apoptosis, and angiogenesis may give therapeutically beneficial insight to develop the management plan of HNC patients and improve their clinical outcomes.     

Optimum block replacement policy over a random time horizon

In this paper we consider the block replacement policy (BRP) for a system operating over a random time horizon. Under such a policy, a system is replaced by a new one either at failure or at a given time interval. The optimality criterion is the expected total replacements cost. Conditions under which an optimal replacement period exits are given. It is shown that BRP over an infinite time horizon is obtained as a particular case of the present work. A numerical example is given to illustrate the proposed replacement model.     

Scheduling two-stage hybrid flow shop with availability constraints

Most of the literature on scheduling assumes that machines are always available. However, in real life industry, machines may be subject to some unavailability periods due to maintenance activities such as breakdowns (stochastic case) and preventive maintenance (deterministic case). In this paper we investigate the two-stage hybrid flow shop scheduling problem with only one machine on the first stage and m machines on the second stage to minimize the makespan. We consider that each machine is subject to at most one unavailability period. The start time and the end time of each period are known in advance (deterministic case) and only the non-resumable case is studied. First we discuss the complexity of the problem. Afterwards, we give the Branch and Bound model for this problem. Last, we calculate the worst-case performances of three heuristics: LIST algorithm, LPT algorithm and H-heuristic.     

A four variable refined plate theory for nonlinear cylindrical bending analysis of functionally graded plates under thermomechanical loadings

In this paper we present a new application for a four variable refined plate theory to analyse the nonlinear cylindrical bending behavior of functionally graded plates subjected to thermomechanical loadings. This recent theory is based on the assumption that the transverse displacements consist of bending and shear components in which the bending components do not contribute toward shear forces and, likewise, the shear components do not contribute toward bending moments. The theory accounts for a quadratic variation of the transverse shear strains across the thickness, and satisfies the zero traction boundary conditions on the top and bottom surfaces of the plate without using shear correction factors. The material properties are assumed to vary continuously through the thickness of the plate according to a power-law distribution of the volume fraction of the constituents. The non-linear strain-displacement relations in the von Karman sense are used to study the effect of geometric non-linearity. The solutions are achieved by minimizing the total potential energy and the results are compared to the classical and the first-order theories reported in the literature. It can be concluded that the proposed theory is accurate and simple in solving the nonlinear cylindrical bending behavior of functionally graded plates.     

Reliability Prediction of Composite Tubular Structure Under Mechanical Loading by Finite Element Method

The diversified use of filamentary composites in harsh marine environments, recorded in recent years, has prompted researchers to focus their work on the reliability prediction. Through failure criteria, Tsai–Wu and the maximum stress, the reliability of multilayer tubular structures under mechanical loading is the subject of this paper, where Monte Carlo method estimated the failure probability. A sensitivity analysis was performed in order to identify the influence of the different parameters, such as materials’ properties, geometry, manufacturing and loading, on the reliability of the composite cylindrical structure studied. To achieve a high accuracy of the results, we have carried out 105 simulations. The results showed great influence on pressure loading, ply thickness and finally winding angle of filament composite.     

Understanding the Corrosion Inhibition Mechanism of Mild Steel in Hydrochloric Acid by a Triazole Derivative: A Combined Experimental and Theoretical Approach

Protection of Metals and Physical Chemistry of Surfaces - The effect of an heterocycle triazole, namely (1-(4-methoxyphenyl)-1H-1,2,3-triazol-4-yl)methanol (MTM) on the corrosion of mild steel in...     

Periodic autoregressive conditional duration

We propose an autoregressive conditional duration (ACD) model with periodic time-varying parameters and multiplicative error form. We name this model periodic autoregressive conditional duration (PACD). First, we study the stability properties and the moment structures of it. Second, we estimate the model parameters, using (profile and two-stage) Gamma quasi-maximum likelihood estimates (QMLEs), the asymptotic properties of which are examined under general regularity conditions. Our estimation method encompasses the exponential QMLE, as a particular case. The proposed methodology is illustrated with simulated data and two empirical applications on forecasting Bitcoin trading volume and realized volatility. We found that the PACD produces better in-sample and out-of-sample forecasts than the standard ACD.     

An exploration of corrosion inhibition of mild steel in sulphuric acid solution through experimental study and Monte Carlo simulations

Abstract

4-[4-(1H-imidazol-1-yl)methyl)-1H-1,2,3-triazol-1-yl]methylbenzophenone (ITBP) and 4[4-(1H-1,2,4-triazol-1-yl)methyl)-1H-1,2,3-triazol-1-yl]methylbenzophenone (TTBP) are synthesized as new heterocyclic compounds of the triazole derivative family and tested successfully as potential inhibitors for MS in 1?M H₂SO₄ corrosive medium by using gravimetric analysis, electrochemical impedance spectroscopy, potentiodynamic polarization, and energy dispersive X-ray spectroscopy (EDX). Polarization curves show that the tested inhibitors are mixed-type inhibitors. Scanning electron microscopy (SEM) affirmed the existence of an adsorbed film on the steel surface. Monte Carlo simulations were in excellent agreement with the experimental tests.

Abbreviation: PDP: Potentiodynamic Polarization; EIS: Electrochemical impedance spectroscopy; DFT: Density functional theory; MC: Monte Carlo     

Electrodeposition of lead dioxide on Fe electrode: application to the degradation of Indigo Carmine dye

Journal of Applied Electrochemistry - The modification of an iron electrode was carried out according to the following two steps. In a first step, a cathodic reduction is performed to form a film...