Search

Introduction Methods Findings Discussion We aimed to evaluate the relationship between carotid intima‐media thickness (CIMT), which is a known indicator of cardiovascular risk and atherosclerosis, and uric acid level, which may be an easy marker for cardiovascular diseases due to its antioxidant and pro‐oxidant properties in hemodialysis patients.In this cross‐sectional study, we evaluated 77 hemodialysis patients. The mean CIMT of these patients was measured and recorded by Doppler ultrasonography. Patients were divided into two groups according to their serum uric acid levels. Correlation analysis and linear regression analysis were used to define the relationship between study parameters.The mean CIMT levels in the normouricemic group and the hyperuricemic group were 0.95 ± 0.15 and 1.07 ± 0.15, respectively. There was a statistically significant difference between the two groups (p = 0.001). There was a statistically significant and moderate linear correlation between serum uric acid level and mean CIMT (r = 0.402; p = 0.002). Univariate and multivariate linear regression analyses were performed to identify variables that could independently affect the mean CIMT value. According to analysis, uric acid (p < 0.001), hypertension (p = 0.008), albumin (p = 0.029), and C‐reactive protein (p = 0.042) were found independent risk factors for mean CIMT value.We found a significant relationship between serum uric acid level and CIMT, which indicates carotid atherosclerosis. Serum uric acid level is a low‐cost laboratory parameter that can be measured in almost all laboratories, and it may be valuable in the hemodialysis patient group to identify patients at high risk of carotid atherosclerosis. [ABSTRACT FROM AUTHOR]

The global pandemic of metabolic diseases has increased the incidence of hepatocellular carcinoma (HCC) in the context of non‐alcoholic steatohepatitis (NASH). The downregulation of the E3 ubiquitin ligase TRIM21 has been linked to poor prognosis in different cancers including HCC. In order to investigate the role of TRIM21 in liver cancer progression on NASH, Trim21+/+ and Trim21−/− male mice were injected with streptozotocin at the neonatal stage. The hypoinsulinemic mice were then fed with a high‐fat high‐cholesterol diet (HFHCD) for 4, 8 or 12 weeks. All mice developed NASH which systematically resulted in HCC progression. Interestingly, compared to the Trim21+/+ control mice, liver damage was worsened in Trim21−/− mice, with more HCC nodules found after 12 weeks on HFHCD. Immune population analysis in the spleen and liver revealed a higher proportion of CD4+PD‐1+ and CD8+PD‐1+ T cells in Trim21−/− mice. The liver and HCC tumors of Trim21−/− mice also exhibited an increase in the number of PD‐L1+ and CD68+ PD‐L1+ cells. Thus, TRIM21 limits the emergence of HCC nodules in mice with NASH by potentially restricting the expression of PD‐1 in lymphocytes and PD‐L1 in tumors. [ABSTRACT FROM AUTHOR]

A highly sensitive microwave sensor for solid material characterization is proposed. A novel design consisting of split ring resonators (SRRs) within a three‐port power divider is developed. The three‐port junction is employed as the host to provide two output channels, and SRRs are loaded through electric coupling to the power divider as the sensing area. The SRRs are located symmetrically so that any change in the electric field of the SRRs is transferred equally to the transmission coefficients of the three‐port junction. The operation of the proposed sensor is based on the downshifting of the transmission zero caused by the loading of samples. The two identical outputs help to control cross‐sensitivity due to external effects. The performance of the fabricated prototype on a 22.2 × 18.8 × 1.6 mm3 printed circuit board is presented. It is shown that a 135 MHz shift per unit relative permittivity change can be achieved. The normalized sensitivity is found to be 3%, which is relatively higher than the sensors reported in the literature. [ABSTRACT FROM AUTHOR]

As the millimeter‐wave (mm‐Wave) spectrum is considered to be an essential enabler to the fifth generation (5G) wireless communication systems. Human movements are one of the most significant factors that cause transient blockage in indoor mm‐wave channels. In this letter, human blockage measurements and shadow fading statistics due to human body movements in an indoor office environment are reported for the 28 GHz band. The effect of human bodies on the channel is measured for several scenarios including a variety of population and using diverse antenna heights. The reported shadow fading statistics include both the duration and the depth of the blockage fade, and accordingly, we propose several empirical models that cater for such blockage events. The findings reported in this letter could improve the modeling of indoor radio channels at 28 GHz bands by considering the presence of humans, as well as their movements. [ABSTRACT FROM AUTHOR]

Summary: The number of satellites has been increasing in both geostationary (GEO) and non‐geostationary (NGEO) earth orbits. Due to the limited availability of spectrum resources, the interference risk among these satellite networks has been increasing consequently. In such a scenario, the protection of existent GEO transmissions is crucial. In this paper, the co‐existence downlink interference from a typical low earth orbit (LEO) constellation to earth stations of GEO satellites is examined for minimization of exclusion zone on the equatorial region. Two different operational scenario based on modulation and coding (MODCOD) with/without spread spectrum for the LEO system are considered. A multiobjective optimization problem (MOP) is formulated for nondominant solutions set based on exclusive angle minimization and bandwidth utilization of the LEO link. It is shown that the exclusive angle can be reduced up to 21.3% and 19.6%, compared with the initial anchor point at the transmission bit rates of 100 and 200 Mbps, respectively. The proposed optimal operational setting minimizes the interference risk to the GEO satellite network as well as maintains quality of service (QoS) for the LEO communication network. The results provide optimal operational mode selection for LEO satellite operators and/or decision makers. [ABSTRACT FROM AUTHOR]

Radio frequency fingerprinting (RFF) is used as a physical‐layer security method to provide security in wireless networks. Basically, it exploits the distinctive features (fingerprints) extracted from the physical waveforms emitted from radio devices in the network. One of the major challenges in RFF is to create robust features forming the fingerprints of radio devices. Here, dual‐tree complex wavelet transform (DT‐CWT) provides an accurate way of extracting those robust features. However, its performance on the RFF of Bluetooth transients which fall into narrowband signaling has not been reported yet. Therefore, this study examines the performance of DT‐CWT features on the use of transient‐based RFF of Bluetooth devices. Initially, experimentally collected Bluetooth transients from different smartphones are decomposed by DT‐CWT. Then, the characteristics and statistics of the wavelet domain signal are exploited to create robust features. Next, the support vector machine (SVM) is used to classify the smartphones. The classification accuracy is demonstrated by varying channel signal‐to‐noise ratio (SNR) and the size of transient duration. Results show that reasonable accuracy can be achieved (lower bound of 88%) even with short transient duration (1024 samples) at low SNRs (0–5 dB). [ABSTRACT FROM AUTHOR]

Recently, a concept of linear wireless sensor networks (LWSNs) has attracted much attention. For such networks, one of the key challenges in sensor node design is to couple transceiver modules with bidirectional antennas placed back‐to‐back for opposite radiation. As is known, simply, this can be achieved by using well‐known coupling options like radio frequency (RF) switch or splitter. However, it is important to decide between two seemingly equally good options according to the system requirements such as RF performance, power consumption, and cost. Therefore, this study aims to comparatively assess these options from the system level point of view to find out what advantages or disadvantages either provides as per the other from widespread use of them in a LWSN‐based cathodic protection monitoring of oil and natural gas pipelines in extreme environments. Preliminary field tests are also conducted to validate the efficiency of coupling options for LWSN links. Results show that RF splitter offers low power consumption and cost whereas RF switch has advantages of low loss. Thus, it is believed that this study may provide useful insights to design bidirectional sensor links for LWSNs. [ABSTRACT FROM AUTHOR]

Summary In recent years, technological developments with user demands, reduced production, and launch costs have rapidly increased the number of Low Earth Orbit (LEO) satellites in space. Since LEO satellites use the same frequency band as existing Geostationary Earth Orbit (GEO) satellites, the interference coordination between the two satellite networks is vital. In order to minimize the co‐existent interference between these satellite networks, studies perform on different interference mitigation strategies. In this paper, analysis and comparative assessment of these interference mitigation techniques are presented for the co‐existent Non‐Geostationary Earth (NGEO) and GEO systems. More specifically, power control (PC) and spatial isolation‐based link adaptation (SILA) techniques are studied comparatively for the performance evaluation. It is shown that the communication link bandwidth is more efficiently utilized in the SILA technique when compared with the PC technique. Moreover, the multi‐objective optimization problem (MOP) approach in the SILA technique is demonstrated to be more effective when compared with the single‐objective optimization problem (SOP) approach used in the PC technique as the simultaneous prioritizing objective functions outperforms single prioritization. Finally, it is shown that when the PC technique is applied together with the SILA technique, the exclusive angle (EA) can be reduced up to 8% for 100 Mbps, and 8.5% for 200 Mbps transmission bit rates in different operational scenarios. The presented performance evaluation in this paper may help the satellite operator or decision‐maker gain insights on which mitigation technique can be used in the case of a co‐existent interference. [ABSTRACT FROM AUTHOR]

Summary: The fifth generation (5G) technology is expected to allow connectivity to billions of devices, known as Internet of Things (IoT). However, IoT devices will inevitably be the main target of various cyberattack types. The most common one is known as distributed denial‐of‐service (DDoS) attack. In order to mitigate such attacks, network functions virtualization (NFV) has a great potential to provide the benefit of elasticity and low‐cost solutions for protecting 5G networks. In this context, this study proposes a new mechanism developed to mitigate DDoS attacks in 5G NFV networks. The proposed mechanism utilizes intrusion prevention system's (IPS) virtual machines (VMs) to intercept the queries. Based on the volume of DDoS traffic, IPS's VMs are dynamically deployed by means of management and orchestration (MANO) in order to balance the load. To evaluate the effectiveness of the mechanism, experiments are conducted in a real 5G NFV environment built by using 5G NFV environment tools. To our best knowledge, this is the first time that NFV‐based mechanism is experimentally tested in a real 5G NFV environment for mitigating DDoS attacks in 5G networks. The experimental results verify that the proposed mechanism can mitigate DDoS attacks effectively. [ABSTRACT FROM AUTHOR]

This article indicates a thus far unexplored area of applied research and development to the application and system engineers and researchers from broad engineering backgrounds. Results of a study are presented for measurement of calibrated Radar Cross Section (RCS) of a 9‐mm bullet (projectile) model by using a commercial‐of‐the‐shelf (COTS) millimeter wave Frequency Modulated Continuous Wave (FMCW) radar system operating in 77 to 81 GHz frequency range. The calibrated RCS variation against the aspect angle is measured experimentally, analyzed, and compared with the simulation results which shows fair matching between the two. The opportunities and challenges attached with the use of such COTS systems for development of Hostile Fire Indication (HFI) systems are discussed. This bullet type and this mmwave frequency has not been thus far studied and reported in literature. This may motivate interested individuals/entities to try to measure (at acceptable accuracy before anechoic chamber measurements) RCS of similar low‐size objects by using such low‐cost COTS platforms. [ABSTRACT FROM AUTHOR]

The methods used in engineering education have gained diversity in parallel with rapidly evolving technology. New technological methods along with the traditional methods have been adopted for undergraduate education. Today, Simulink‐based educational materials are used in many fields in engineering education. However, in the literature, the contribution of such educational materials to the learning process has not been measured thoroughly. This study presents a comprehensive measurement method to improve the created course material and show the effectiveness of developed course material in students' success. First, educational material was developed for an undergraduate electrical engineering course: communication systems. A feedback group made up of diverse student learners was employed extensively in the material development phase. Next, the impact of the developed material on the success of the students was examined using both qualitative and quantitative measurement tools including questionnaires, one‐to‐one interviews, and class and university level anonymous surveys. This also included students' performance regarding laboratory quizzes and achievement of course learning outcomes. Overall, the measurement results show that the course material increased students' success in the course. Moreover, students' general perception of the course material was positive. [ABSTRACT FROM AUTHOR]

This study presents the design and the fabrication of a miniaturised sub-GHz antenna for remote control applications. Miniaturisation techniques were examined to identify the most appropriate topology for sub-GHz band requirements. First, the design parameters of the antenna were determined, and then, a commercial electromagnetic simulation tool was used for the design and optimisation phases. Then, measurements of the fabricated antenna were undertaken. Parametric studies with several iterations were performed to achieve the best possible results. Second, the effects of the box in which the antenna could be placed were examined as most of such antennas are enclosed by plastic boxes. For this purpose, material properties of a typical industrial box available in the market were studied initially, and the most appropriate material of the box was used in simulations. Finally, a polyamide box with appropriate size was fabricated, and the designed antenna was placed inside the box and the measurements were conducted. The measurement results show that the designed antenna provides resonance at the targeted license-free band with adequate size for industrial remote controllers. [ABSTRACT FROM AUTHOR]

This paper presents a better understanding of the use of finite integration techniques (FIT) and finite element method (FEM) in different types of microstrip antennas in order to determine which numerical method gives relatively more accurate results. Although the theoretical formulation based on Maxwell's equations of both FEM and FIT are approached from different aspects in the literature, there is still a lack of comparison of the same antenna type using different numerical methods employing FEM and FIT. Therefore, in this study, FEM and FIT were applied to two different types of microstrip antennas, and their simulation and experimental results was compared. For the first antenna demonstration, a multilayer structure was chosen to achieve one of the significant parameters. Then, a microstrip antenna with a compact structure was used in the second demonstration. Using these two antennas, the accuracy of FEM and FIT in different structures were compared and all simulated return loss and gain results were verified by the measured results. The experimental demonstrations show that FEM performs better for both types of microstrip antennas while FIT provides an adequate result for two‐layer microstrip antennas. [ABSTRACT FROM AUTHOR]

In this study, antimicrobial pigment cinnabarinic acid (CA) was produced from Pycnoporus cinnabarinus in laboratory-scale batch cultures. Magnetic poly(ethylene glycol dimethacrylate- N-methacryloyl-l-tryptophan methyl ester) [ m-poly(EGDMA-MATrp)] beads (average diameter = 53-103 µm) were synthesized by copolymerizing of N-methacryloyl-l-tryptophan methyl ester (MATrp) with ethylene glycol dimethacrylate (EGDMA) in the presence of magnetite (Fe3O4) and used for the adsorption of CA. The m-poly(EGDMA-MATrp) beads were characterized by N2 adsorption/desorption isotherms (Brunauer Emmet Teller), X-ray photoelecron spectroscopy, scanning electron microscopy, infrared spectroscopy, thermal gravimetric analysis, electron spin resonance and swelling studies. The efficiency of m-poly(EGDMA-MATrp) beads for separation of CA from culture fluid was evaluated. The effects of pH, initial concentration, contact time and temperature on adsorption were analyzed. The maximum CA adsorption capacity of the m-poly(EGDMA-MATrp) beads was 272.9 mg g−1 at pH 7.0, 25 °C. All the isotherm data can be fitted with the Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. The adsorption process obeyed pseudo-second-order kinetic model. Thermodynamic parameters Δ H = 5.056 kJ mol−1, Δ S = 52.44 J K−1 mol−1 and Δ G = −9.424 kJ mol−1 to -11.27 kJ mol−1 with the rise in temperature from 4 to 40 °C indicated that the adsorption process was endothermic and spontaneous. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Key Clinical Message Hepatic abscess due to Brucella species is an extremely rare complication especially in acute illness. Here, we report a case of hepatic microabscesses probably caused by Brucella in a 33-year-old woman with acute infection who was successfully treated with a combination of doxycycline and rifampicin for 3 months. [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, the use of the potentiometric method for the determination of the protonation constant of vinyl imidazole (VIM) and the stability constant of the Cu2+ ion complex of VIM used in the immobilized metal ion affinity chromatography (IMAC) was investigated. For this purpose, poly(ethylene glycol dimethacrylate- n-vinyl imidazole) [poly(EGDMA-VIM)] microspheres (average diameter 150-200 μm) were prepared. The microspheres were characterized by elemental analysis, N2 adsorption/desorption isotherms, elemental analysis, energy dispersive spectroscopy (EDS). Protonation constants of vinyl imidazole and the metal-ligand stability constant of vinyl imidazole with Cu2+ ions have been determined potentiometrically in 0.1 M NaCl aqueous solution at 298, 318, and 338 K, respectively. The corresponding thermodynamic parameters of protonation and complexation processes (Δ G, Δ H, and Δ S) were derived and discussed. The formation kinetics of Cu2+-vinyl imidazole complex were also investigated, and the process obeyed the pseudo-second-order kinetic model. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39751. [ABSTRACT FROM AUTHOR]

Single-walled carbon nanotube (SWCNT) polyvinylimidazole (PVI) composites have been prepared by in situ emulsion polymerization. Dispersion of raw SWCNTs in the PVI matrix was improved by surface modification of the SWCNTs using nitric acid treatment and air oxidation. The carbonyl-terminated SWCNTs were covalently bonded to PVI by in situ polymerization and the SWCNT/PVI composite was thus obtained. The morphological and structural characterizations of the surface-functionalized SWCNTs and SWCNT/PVI composites were carried out by Fourier transform infrared spectroscopy, X-ray diffraction, conductivity measurements, scanning, and transmission electron microscopy. Thermograms of the materials were determined by the differential scanning calorimetry technique. The characterization results indicate that PVI was covalently bonded to SWCNTs and a new material was then obtained. The functionalized SWCNTs showed homogenous dispersion in the composites, whereas purified SWCNT resulted in poor dispersion and nanotube agglomeration. SWCNT/PVI composites exhibited chemical stability enhancement in many common solvents. I-V curves of the samples exhibit an ohmic character. Conductivity values for pure SWCNTs, pure PVI and SWCNT/PVI composite were measured to be 3.47, 2.11 × 10−9, and 2.3 × 10−3 S/m, respectively. Because of resonance, a large dielectric constant is obtained for SWCNT/PVI composite, which is not observed for ordinary materials. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Poly(ethylene glycol dimethacrylate-1-vinyl-1,2,4-triazole) [poly(EGDMA-VTAZ)] beads with an average diameter of 100-200 μm were obtained by the copolymerization of ethylene glycol dimethacrylate (EGDMA) with 1-vinyl-1,2,4-triazole (VTAZ). The copolymer hydrogel bead composition was determined by elemental analysis and was found to contain 5 EGDMA monomer units for each VTAZ monomer unit. The poly(EGDMA-VTAZ) beads were characterized by swelling studies and scanning electron microscopy (SEM). The specific surface area of the poly(EGDMA-VTAZ) beads was found 65.8 m/g. Cu ions were chelated on the poly(EGDMA-VTAZ) beads. The Cu loading was 82.6 μmol/g of support. Cu-chelated poly(EGDMA-VTAZ) beads with a swelling ratio of 84% were used in the immobilization of Aspergillus niger glucoamylase in a batch system. The maximum glucoamylase adsorption capacity of the poly(EGDMA-VTAZ)-Cu beads was 104 mg/g at pH 6.5. The adsorption isotherm of the poly(EGDMA-VTAZ)-Cu beads fitted well with the Langmuir model. Adsorption kinetics data were tested with pseudo-first- and second-order models. The kinetic studies showed that the adsorption followed a pseudo-second-order reaction model. The Michaelis constant value for the immobilized glucoamylase (1.15 mg/mL) was higher than that for free glucoamylase (1.00 mg/mL). The maximum initial rate of the reaction values were 42.9 U/mg for the free enzyme and 33.3 U/mg for the immobilized enzyme. The optimum temperature for the immobilized preparation of poly(EGDMA-VTAZ)-Cu-glucoamylase was 65°C; this was 5°C higher than that of the free enzyme at 60°C. The glucoamylase adsorption capacity and adsorbed enzyme activity slightly decreased after 10 batch successive reactions; this demonstrated the usefulness of the enzyme-loaded beads in biocatalytic applications. The storage stability was found to increase with immobilization. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

The article discusses a study which synthesized magnetic beads for the removal of heavy-metal ions from synthetic solutions. It notes the suspension polymerization was used in this study to produce the magnetic beads. Particular focus is given to the specific surface area of the magnetic beads, as well as its swelling ratio. It cites the average magnetite content of the resulting beads, along with its maximum binding capacities.

The article presents a study which investigated the adsorption of ions of chromium(VI) (Cr(VI)) onto poly(ethylene glycol dimethacrylate-1-vinyl-1,2,4-triazole) [poly(EGDMA-VTAZ)]. Poly(EGDMA-VTAZ) beads were prepared by copolymerizing ethylene glycol dimethacrylate (EGDMA) with 1-vinyl-1,2,4-triazole (VTAZ). Results showed that the adsorption of metal ions onto poly(EGDMA-VTAZ) was favorable.

Trimetazidine is a widely used anti-ischemic agent, but effects of its chronic treatment on myocardial preconditioning in anesthetized animals have not been investigated. The aim of this study was to examine the effects of 15-day treatment of trimetazidine on ischemic preconditioning and carbachol-induced preconditioning in anesthetized rats. Ischemic preconditioning, induced by 5 min of coronary artery occlusion and 5 min of reperfusion, significantly decreased the total number of ventricular ectopic beats, the incidence of ventricular tachycardia and abolished the occurrence of ventricular fibrillation (VF) during 30 min of ischemia. Trimetazidine (10 mg/kg/day, i.p. for 15 days and 10 mg/kg, i.v.) itself attenuated these arrhythmia parameters with no marked effect on hemodynamic effects. In the presence of trimetazidine, anti-arrhythmic effects of ischemic preconditioning were present. Carbachol infusion induced preconditioning with a marked depression of mean arterial blood pressure, heart rate and the total number of ventricular ectopic beats. No VF was observed in carbachol-induced preconditioning. The marked reductions in arrhythmia parameters that induced carbachol-induced preconditioning were also preserved in the presence of trimetazidine. Arrhythmia scores and myocardial infarct size were reduced significantly with ischemic preconditioning or carbachol-induced preconditioning and were not modified by trimetazidine. Lactate and malondialdehyde levels were suppressed significantly with preconditioning or trimetazidine + preconditioning groups. These results show that chronic treatment of trimetazidine protects the heart against ischemia-induced arrhythmias, reduces myocardial infarct size, plasma lactate and malondialdehyde levels, and preserves the effects of ischemic and pharmacological preconditioning in anesthetized rats. [ABSTRACT FROM AUTHOR]