Characterization of Double-Junction GaAsP Two-Color LED Structure

The structural, optical, electrical and electrical–optical properties of a double-junction GaAsP light-emitting diode (LED) structure grown on a GaP (100) substrate by using a molecular beam epitaxy technique were investigated. The p–n junction layers of GaAs_1?xP_x and GaAs_1?yP_y, which form the double-junction LED structure, were grown with two different P/As ratios. High-resolution x-ray diffraction (HRXRD), photoluminescence (PL), and current–voltage (I–V) measurements were used to investigate the structural, optical and electrical properties of the sample. Alloy composition values (x, y) and some crystal structure parameters were determined using HRXRD measurements. The phosphorus compositions of the first and second junctions were found to be 63.120% and 82.040%, respectively. Using PL emission peak positions at room temperature, the band gap energies (E_g) of the first and second junctions were found to be 1.867 eV and 2.098 eV, respectively. In addition, the alloy compositions were calculated by Vegard’s law using PL measurements. The turn-on voltage (V_on) and series resistance (R_s) of the device were obtained from the I–V measurements to be 4.548 V and 119 Ω, respectively. It was observed that the LED device emitted in the red (664.020 nm) and yellow (591.325 nm) color regions.     

The effect of cement alkali content on ASR susceptibility of mortars incorporating admixtures

In this study, the effects of three types of plasticizing chemical admixtures (modified lignosulfonate, sulfonated naphthalene formaldehyde and polycarboxylate based) on deleterious expansion due to alkali–silica reaction (ASR) have been investigated. Two different types of cements with low (0.53 Na₂O eq.) and high (0.98 Na₂O eq.) alkali contents, a non-reactive crushed limestone as fine aggregate and a reactive river sand were used within the scope of the experimental program. ASR tests were conducted according to accelerated mortar bar method (ASTM C 1260). Additionally the flow value, dry unit weight, capillary water absorption and compressive strength tests were performed. Test results indicated that mortars prepared with inert fine aggregate caused no significant expansion, regardless of cement type, admixture type and dosage. However, for mixes containing reactive sand, admixtures increased or decreased the expansion values (compared to plain mortars) depending on the alkali content of cement used. The magnitude of change of expansion also depended on the type and amount of admixture incorporation which have a dominant effect on stability and compactability of mortars. The high-alkali cement usually revealed the ASR expansion augmentation behaviour of admixtures. In contrast, low alkali cement decreased the expansion values compared to the control specimens.     

Niobium boride coating on AISI M2 steel by boro-niobizing treatment

In this study, niobium boride coating was applied on pre-boronized AISI M2 steel by the thermo-reactive deposition technique in a powder mixture consisting of ferro-niobium, ammonium chloride and alumina at 950 °C for 1-4 h. The coated samples were characterized by X-ray diffraction, scanning electron microscope and micro-hardness tests. Niobium boride layer formed on the pre-boronized AISI M2 steel was smooth, compact and homogeneous. X-ray studies showed that the phases formed on the steel surfaces are NbB, Nb₃B₂, FeB and Fe₂B. The depth of the niobium boride layer ranged from 0.97 μm to 3.25 μm, depending on treatment time. The higher the treatment time the thicker the niobium boride layer observed. The hardness of the niobium boride layer was 2738 ± 353 HV_0.01.     

Artificial intelligence control for trust-based detection of attackers in 5G social networks

This study introduces a comprehensive framework designed for detecting and mitigating fake and potentially threatening user communities within 5G social networks. Leveraging geo-location data, community trust dynamics, and AI-driven community detection algorithms, this framework aims to pinpoint users posing potential harm. Including an artificial control model facilitates the selection of suitable community detection algorithms, coupled with a trust-based strategy to effectively identify and filter potential attackers. A distinctive feature of this framework lies in its ability to consider attributes that prove challenging for malicious users to emulate, such as the established trust within the community, geographical location, and adaptability to diverse attack scenarios. To validate its efficacy, we illustrate the framework using synthetic social network data, demonstrating its ability to distinguish potential malicious users from trustworthy ones.     

Determination of the structural properties of a columnar hexagonal liquid crystal by light scattering

In this study we examine a new computer model of light scattering. Light propagation through a columnar hexagonal liquid crystal has been represented by using a cylindrical model. Numerical aspects of the light scattering process, which are based on numerically solving Maxwell's equations, have been calculated for a liquid crystal. We describe in detail the circular cylindrical model for computing light scattering from a columnar hexagonal liquid crystal and present the results of benchmark computations. We report results of extensive calculation for oriented columnar molecular systems. Our results are compared with previous studies on light scattering by other materials.     

Platelet‐to‐lymphocyte ratio better predicts inflammation than neutrophil‐to‐lymphocyte ratio in end‐stage renal disease patients

Neutrophil‐to‐lymphocyte ratio (NLR) was introduced as a potential marker to determine inflammation in end‐stage renal disease (ESRD) patients. Recently, platelet‐to‐lymphocyte ratio (PLR) and NLR were found to positively correlated with inflammatory markers including tumor necrosis factor‐α (TNF‐α) and interleukin (IL)‐6 in cardiac and noncardiac patients. Data regarding PLR and its association with inflammation are lacking in hemodialysis (HD) and peritoneal dialysis (PD) patients. Hence, we aimed to determine the relationship between PLR, NLR, and inflammation in ESRD patients. This was a cross‐sectional study involving 62 ESRD patients (29 females, 33 males; mean age, 49.6 ± 14.6 years) receiving PD or HD for ≥6 months in the Dialysis Unit of Necmettin Erbakan University. PLR, NLR, C‐reactive protein, TNF‐α, IL‐6 levels were measured. PLR, NLR, serum high sensitive C‐reactive protein, IL‐6, and TNF‐α levels were significantly higher in PD patients when compared with HD patients. ESRD patients with PLR ≥ 140 had significantly higher NLR, IL‐6, and TNF‐α levels when compared to patients with PLR < 139. In the bivariate correlation analysis, PLR was positively correlated with NLR, IL‐6, and TNF‐α in this population. When we compared the association of PLR and NLR with IL‐6 (r = 0.371, P = 0.003 vs. r = 0.263, P = 0.04, respectively) and TNF‐α (r = 0.334, P = 0.008 vs. r = 0.273, P = 0.032, respectively), PLR was found to be superior to NLR in terms of inflammation in ESRD patients. Simple calculation of PLR can predict inflammation better than NLR in ESRD patients.     

A taxonomy and evaluation for developing 802.11‐based wireless mesh network testbeds

The definition of wireless mesh networks (WMNs) has been used in the literature to connote and epitomize the ideal, ubiquitous, pervasive, and autonomic networking technology. An increasing interest has been emerging on the development of 802.11‐based WMN testbeds to test the new ideas and approaches more realistically as opposed to relying solely on simulations. Although the developed testbeds have provided several insights to researchers for furthering the technology, there are still several issues that need to be addressed, particularly, with the approval of new standards, such as IEEE 802.11s, IEEE 802.11n, and IEEE 802.16, and upcoming protocols, such as IEEE 802.11ac, 802.11ad, 802.11ah, and 802.11af TV White Space efforts. In this paper, our goal is to provide a taxonomy and insightful guidelines for the creation of 802.11‐based WMN testbeds as well as to identify several features that future WMN testbeds should possess. Utilizing these features, we evaluate the existing WMN testbeds. Finally, in addition to the existing WMN testbed experiments conducted at several layers of the protocol stack, we provide a list of open future research issues that can benefit from experiments on WMN testbeds. Copyright © 2011 John Wiley & Sons, Ltd.     

Effects of Er:YAG laser on bond strength of self‐etching adhesives to caries‐affected dentin

The erbium:yttrium–aluminum–garnet (Er:YAG) laser may be effective the bond strength of adhesive systems on dentine surfaces, the chemical composition and aggressiveness of adhesive systems in clinical practice. The purpose of this study was to evaluate the effects of the Er:YAG laser system with the bonding ability of two different self‐etching adhesives to caries‐affected dentine in primary molars. Ninety mid‐coronal flat dentine surfaces obtained from sound and caries‐affected human primary dentine were treated with an Er:YAG laser or a bur. The prepared surfaces were restored with an adhesive system (Xeno V; Clearfil S³) and a compomer (Dyract Extra). The restored teeth were sectioned with a low‐speed saw and 162 samples were obtained. The bond strength of the adhesive systems was tested using the micro‐tensile test method. The data were statistically analyzed. A restored tooth in each group was processed for scanning electron microscopy evaluation. The values of the highest bond strength were obtained from the Clearfil S³‐Er:YAG laser‐sound dentine group in all groups. (24.57 ± 7.27 MPa) (P > 0.05). The values of the lowest bond strength were obtained from the Xeno V‐Er:YAG laser‐sound dentine group in all groups (11.01 ± 3.89 MPa). It was determined that the Clearfil S³ increased the bond strength on the surface applied with Er:YAG laser according to the Xeno V. Microsc. Res. Tech. 77:282–288, 2014. © 2014 Wiley Periodicals, Inc.     

Graph run-length matrices for histopathological image segmentation

The histopathological examination of tissue specimens is essential for cancer diagnosis and grading. However, this examination is subject to a considerable amount of observer variability as it mainly relies on visual interpretation of pathologists. To alleviate this problem, it is very important to develop computational quantitative tools, for which image segmentation constitutes the core step. In this paper, we introduce an effective and robust algorithm for the segmentation of histopathological tissue images. This algorithm incorporates the background knowledge of the tissue organization into segmentation. For this purpose, it quantifies spatial relations of cytological tissue components by constructing a graph and uses this graph to define new texture features for image segmentation. This new texture definition makes use of the idea of gray-level run-length matrices. However, it considers the runs of cytological components on a graph to form a matrix, instead of considering the runs of pixel intensities. Working with colon tissue images, our experiments demonstrate that the texture features extracted from "graph run-length matrices" lead to high segmentation accuracies, also providing a reasonable number of segmented regions. Compared with four other segmentation algorithms, the results show that the proposed algorithm is more effective in histopathological image segmentation.     

Motives for Facebook use and expressing “true self” on the Internet

A survey on 143 university students was conducted to examine what motives young adults have for Facebook use, which of those motives were endorsed more than the others, and how those motives were related to the tendency of expressing one’s “true self” through Facebook use. According to the results, primary motive for Facebook use was to maintain long-distance relationships. This motive was followed by game-playing/entertainment, active forms of photo-related activities, organizing social activities, passive observations, establishing new friendships, and initiating and/or terminating romantic relationships. Another interesting result was that individuals’ tendency for expressing one’s true self on the Net had an influence on their Facebook use motives: The ones with high tendency to express their true self on the Internet reported to use Facebook for establishing new friendships and for initiating/terminating romantic relationships more than the individuals’ with low and medium levels of the same tendency did.