Bee Bread Ameliorates Vascular Inflammation and Impaired Vasorelaxation in Obesity-Induced Vascular Damage Rat Model: The Role of eNOS/NO/cGMP-Signaling Pathway

Obesity and hyperlipidemia are major risk factors for developing vascular diseases. Bee bread (BB) has been reported to exhibit some biological actions, including anti-obesity and anti-hyperlipidemic. This study aims to investigate whether bee bread can ameliorate vascular inflammation and impaired vasorelaxation activity through eNOS/NO/cGMP pathway in obese rats. Forty male Sprague-Dawley rats were randomly divided into four groups (n = 10/group), namely: control (normal group), obese rats (OB group), obese rats treated with bee bread (0.5 g/kg/day, OB/BB group) and obese rats treated with orlistat (10 mg/kg/day, OB/OR group). The latter three groups were given a high-fat diet (HFD) for 6 weeks to induced obesity before being administered with their respective treatments for another 6 weeks. After 12 weeks of the total experimental period, rats in the OB group demonstrated significantly higher Lee obesity index, lipid profile (total cholesterol, triglyceride, low-density lipoprotein), aortic proinflammatory markers (tumor necrosis factor-α, nuclear factor-κβ), aortic structural damage and impairment in vasorelaxation response to acetylcholine (ACh). Bee bread significantly ameliorated the obesity-induced vascular damage manifested by improvements in the lipid profile, aortic inflammatory markers, and the impaired vasorelaxation activity by significantly enhancing nitric oxide release, promoting endothelial nitric oxide synthase (eNOS) and cyclic guanosine monophosphate (cGMP) immunoexpression. These findings suggest that the administration of bee bread ameliorates the impaired vasorelaxation response to ACh by improving eNOS/NO/cGMP-signaling pathway in obese rats, suggesting its vascular therapeutic role.     

Electrosynthèse des ions peroxodiphosphate sous potentiel constant ou pulsé

Electrosynthesis of peroxodiphosphate ions (P2O84–) was performed in 2m K3PO4, 1m K2HPO4 medium, using a platinum anode. The results showed that under conditions of potentiostatic polarization at constant potential, the reaction rate reaches a maximum value of 125mAcm–2 and a faradaic yield of 30%. From about 1.9V, the reaction kinetics are increasingly inhibited as the potential shifts positively. Rapid scanning potential voltammetry was used to characterize the oxidation state of the electrode surface. This method shows that the growth of (PtO) and (PtO2 or PtO3) oxides depend on the applied potential. It also establishes a correlation between the inhibition of P2O84– ion electrosynthesis and the oxide coating surface. When 2×10–3m KSCN is added to the solution, some oxygen evolution sites are selectively blocked and oxide occurs at more positive potential values. Consequently, the rate of peroxodiphosphate ion formation and the faradaic efficiency are increased to 380mAcm–2 and 75%, respectively. Under pulsed potential conditions it was possible to reach 1200mAcm–2 for P2O84– ion electrosynthesis with a faradaic yield of 82%.     

An enhanced LBP-based technique with various size of sliding window approach for handwritten Arabic digit recognition

Many variations of local binary pattern (LBP) were proposed to enhance its performance, including uniform local binary pattern (ULBP), center-symmetric local binary patterns (CS-LBP), center symmetric local ternary patterns (CS-LTP), center symmetric local multilevel pattern (CS-LMP), etc. In this paper, the accuracies of LBP technique and its variations are enhanced using four different sizes of a sliding window approach. This approach is used for investigating whether the features extracted by LBP are significant enough or its versions are needed as well. Five LBP-based techniques have been used including LBP, CS-LBP, CS-LTP, CS-LMP, and U2LBP. They have been applied to an Arabic digit image dataset called MAHDBase. Support vector machine (SVM) and random forests are utilized as classifiers. The experimental results show that the obtained accuracies have been improved by 19.56%, 21.43%, 5.63%, 6.51% and 5.62% for CS-LBP, CS-LMP, U2LBP, CS-LTP, and LBP, respectively, when the sliding window approach has been applied and SVM with linear kernel has been used as a classifier. Moreover, the results show that there is no need to use LBP variations to enhance the accuracy if the sliding window is applied because the highest accuracy has been acquired using LBP. At the end, the accuracy of proposed systems has been compared against other state-of-the-art LBP-based techniques showing the significance of the proposed systems.

     

Constructing online switching barriers: examining the effects of switching costs and alternative attractiveness on e-store loyalty in online pure-play retailers

Developing switching barriers to retain customers has become a critical marketing strategy for online retailers. However, research on the role of switching barriers in e-retailing is still limited. Recent trends show that when competitors are just one click away, it is questionable if customer loyalty can be achieved at all in online environments. This leads to the research question on whether switching barriers have any impact on e-loyalty in pure-play retailers. The paper examines the influence of switching barriers on customer retention (i.e., e-store loyalty) and further investigates the moderating effects of switching costs and alternative attractiveness. Data were gathered via a survey of 590 shoppers of online pure-play retailers in the UK. Findings show that customer satisfaction and the two dimensions of switching barriers (perceived switching costs and perceived attractiveness of alternatives) significantly influence customer loyalty. Contrary to findings in earlier studies, it was found that switching costs did not moderate the relationships between satisfaction and loyalty nor between perceived attractiveness of alternatives and loyalty. The paper makes imperative recommendations to develop switching barriers and to foster loyalty along with suggestions for future research.     

Multi‐objective optimization using metaheuristics: non‐standard algorithms

In recent years, the application of metaheuristic techniques to solve multi‐objective optimization problems has become an active research area. Solving this kind of problems involves obtaining a set of Pareto‐optimal solutions in such a way that the corresponding Pareto front fulfils the requirements of convergence to the true Pareto front and uniform diversity. Most of the studies on metaheuristics for multi‐objective optimization are focused on Evolutionary Algorithms, and some of the state‐of‐the‐art techniques belong this class of algorithms. Our goal in this paper is to study open research lines related to metaheuristics but focusing on less explored areas to provide new perspectives to those researchers interested in multi‐objective optimization. In particular, we focus on non‐evolutionary metaheuristics, hybrid multi‐objective metaheuristics, parallel multi‐objective optimization and multi‐objective optimization under uncertainty. We analyze these issues and discuss open research lines.     

Effect of wafer thinning methods towards fracture strength and topography of silicon die

This paper characterizes die damage resulting from various wafer thinning processes. Die fracture strength is measured using ball breaker test with respect to die surface finish. Further study on surface roughness and topography of each surface finish is obtained by atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques. Stress relief process with 25 μm removal is able to strengthen 100 μm wafer by 20.4% using chemical wet etch and 75 μm wafer by 36.4% with plasma etch. Relatively, plasma etching shows higher fracture strength and flexibility compared to chemical wet etch. This is due to topography of the finished surface of plasma etch is smoother and rounded, leading to a reduced stress concentration, hence improved fracture strength.     

Wear characteristics of commercial gas turbine components

Wear is one of the common degradations in a commercial gas turbine. A stainless steel grade 304 (SS 304) fuel nozzle and its collar made of nickel-based superalloy (Hastelloy X) are two vital components that normally suffer from rapid wear. During an installation, the fuel nozzle is slotted into the collar of the combustion liner. In operation, these two surfaces are subjected to high pressure from the fuel combustion, hence continuously rubbing against each other causes vibrations. During the start–stop operation, these surfaces had undergone a large relative motion. The vibration is the main cause of the wear occurrence on the surfaces. Physical properties of the worn surfaces were obtained through visual observations: wear measurement, hardness and microstructure examination. Through visual observations, fretting wear was mainly suspected as the dominant wear mode, particularly after 8,000 of running hours at high temperature and vibration. In short, this paper discusses the preliminary findings of wear on the fuel nozzle and its collar. It also discusses the changes in the mechanical properties before and after the operation. Solutions for mitigating the problem were discussed.     

Metallic interconnects for solid oxide fuel cell: A review on protective coating and deposition techniques

With the reduction of solid oxide fuel cells (SOFCs) operating temperature to the range of 600 °C–800 °C, metallic alloy with high oxidation resistance are used to replace traditional ceramic interconnects. Metallic interconnects is advantageous over ceramic interconnects; in terms of manufacturability, cost, mechanical strength, and electrical conductivity. To date, promising candidates for metallic interconnects are all Cr-containing alloys, which are susceptible to volatile Cr migration that causes cell degradation. As such, protective coatings have been developed to effectively inhibit Cr migration; as well as maintain excellent electrical conductivity and good oxidation resistance. This article reviews the progress and technical challenges in developing metallic interconnects; different types of protective coatings and deposition techniques for metallic interconnects for intermediate-temperature SOFC applications.     

The study on the properties of TiCxN1−x coatings processed by cathodic arc physical vapour deposition

Titanium carbonitride (TiCN) is a popular hard coating for carbide cutting tools in various applications. The properties of TiCN are within its composition and can be controlled by maintaining the C–N ratio within the coating to a certain level. This paper studied the influence of carbon content and coating composition within TiC_xN_1?x coatings with regard to their mechanical properties. The substrate used was tungsten carbide (WC-6Co), which was prepared in-house through a powder metallurgy process, while the TiC_xN_1?x coatings were deposited in-house using cathodic arc physical vapour deposition (CAPVD). TiC_xN_1?x coatings improved the mechanical properties of carbide inserts. An increase in carbon content within TiC_xN_1?x coatings improved surface lubricity, reduced coefficient of friction, improved surface microhardness and increased Young's modulus, but reduced thermal conductivity of carbide inserts. The colour of TiC_xN_1?x coatings also changed with carbon content.