Electrochemical copolymerization of carbazole and 2,2′:5′-2″ terthiophene: characterization and micro-capacitor application

In this paper, a copolymer of carbazole (Cz) and 2,2′:5′,2″-terthiophene (TTh) was electropolymerized in 0.1 M sodium perchlorate (NaClO₄)/acetonitrile (CH₃CN) on glassy carbon electrode. The optimum conditions of resulting homopolymers of Cz, TTh and copolymer of Cz and TTh in the initial feed ratio of [Cz]₀/[TTh]₀ = 1/10 were characterized by cyclic voltammetry, Fourier-transform infrared-attenuated total reflectance, scanning electron microscopy, energy dispersive X-ray analysis, and electrochemical impedance spectroscopy. Morphological analysis of copolymer shows that a micro-spherical and web-like morphology was formed for copolymer at different initial feed ratios of [Cz]₀/[TTh]₀ = 1/2, 1/5 and 1/10. The capacitive behavior of the modified electrodes was defined via Nyquist, Bode-magnitude, and Bode-phase plots. The highest low-frequency capacitance (C _LF) was obtained as 4.11 mFcm^?2 in the initial feed ratio of [Cz]₀/[TTh]₀ = 1/10. Double-layer capacitance (C _dl) and phase angles (θ) were obtained for homopolymer and copolymer systems. The highest C _dl was obtained as 2.01 mFcm^?2 for the copolymer in the initial feed ratio of [Cz]₀/[TTh]₀ = 1/2. The highest phase angle of copolymer was obtained as θ = ~75° in the initial feed ratio of [Cz]₀/[TTh]₀ = 1/1. These capacitance results confirmed that films of copolymer Cz/TTh are promising materials for micro-capacitor applications.     

Using timed CSP for specification verification and simulation ofmultimedia synchronization

Timed communicating sequential processes (TCSP) language is used to specify fine-grain and coarse-grain multimedia synchronization. A lip synchronization system is an example of fine-grain synchronization. Several groupware scenarios are examples of coarse-grain synchronization. The formal specifications are used as the basis of verification and simulation. Safety and liveness timing requirements of the synchronization system are stated in terms of temporal logic formulas. Correctness analysis of the specification is shown using the temporal formulas and TCSP proof theory. It is shown that TCSP is powerful enough to be used in multimedia system design and verification. Next, simulation of multimedia synchronization is discussed. Various simulation models are developed for fine- and coarse-grain synchronization systems. It is shown that simulation modeling can lead to early detection of possible synchronization violations. The buffering requirements of a given synchronization mechanism can be effectively studied using simulation     

THE EFFECT OF MAGNESIUM AND CALCIUM ON YEAST GROWTH

When inoculated into a defined minimal medium, yeast could not absorb all the magnesium, even if this element was limiting. The cells tended to absorb a constant amount of magnesium, ca 1·1 pg per cell, so long as the content of the medium was sufficient, rather than absorb magnesium in proportion to its initial concentration. Calcium competed with magnesium and prevented yeast growth almost entirely when present at a ten times excess. At a two to three times excess the effect was more on the length of the lag phase and mean generation time than on the total amount of growth.     

Phytosterols in 17 Turkish hazelnut (Corylus avellana L.) cultivars

The phytosterol contents of the oils from 17 Turkish hazelnut cultivars were determined by gas chromatography with a flame ionization detector. The total phytosterol content varied from 1180.4 (Uzunmusa‐Ordu) to 2239.4 mg/kg (Cavcava), and the average was 1581.6 ± 265.1 mg/kg. One of the most significant commercial cultivars, Tombul, contained quite low total phytosterols (1297.7 mg/kg). Total and individual phytosterol contents of hazelnut cultivars were significantly different at p <0.01, except for phytostanol and campestanol. The main component was β‐sitosterol which ranged from 82.8 to 86.7% in all cultivars. This was followed by campesterol, Δ⁵‐avenasterol, sitostanol and stigmasterol. Interestingly, the same cultivars from different regions showed similar total phytosterol contents, and fall almost within the same range according to Duncan's test, which may indicate that the phytosterol content is highly related to the cultivar.     

Active carbon/graphene hydrogel nanocomposites as a symmetric device for supercapacitors

Activated carbons (ACs) are successfully synthesized from Elaeagnus grain by a simple chemical synthesis methodology and demonstrated as novel, suitable supercapacitor electrode materials for graphene hydrogel (GH)/AC nanocomposites. GH/AC nanocomposites are synthesized via hydrothermal process at temperature of 180°C. The low-temperature thermal exfoliation approach is convenient for mass production of graphene hydrogel (GH) at low cost and it can be used as electrode material for energy storage applications. The GH/AC nanocomposites exhibit better electrochemical performances than the pure GH. Electrochemical performance of the electrodes is studied by cyclic voltammetry, and galvanostatic charge-discharge measurements in 1.0 M H₂SO₄ solution. A remarkable specific capacitance of 602.36 Fg^?1 (based on GH/AC nanocomposites for 0.4 g AC) is obtained at a scan rate of 1 mVs^?1 in 1 M H₂SO₄ solution and 155.78 Fg^?1 for GH. The specific capacitance was increased 3.87 times for GH/AC compared to GH electrodes. Moreover, the GH/AC nanocomposites for 0.2 g AC present excellent long cycle life with 99.8% specific capacitance retained after 1000 charge/discharge processes. Herein, ACs prepared from Elaeagnus grain are synthesized GH and AC supercapacitor device for high-performance electrical energy storage devices as a promising substitute to conventional electrode materials for EDLCs.     

Design and Hardware-in-the-Loop Integration of a UAV Microavionics System in a Manned–Unmanned Joint Airspace Flight Network Simulator

One of the challenges for manned-unmanned air vehicles flying in joint airspace is the need to develop customized but scalable algorithms and hardware that will allow safe and efficient operations. In this work, we present the design of a bus-backboned UAV microavionics system and the hardware-in-the-loop integration of this unit within a joint flight network simulator. The microavionics system is structured around the Controller Area Network and Ethernet bus data backbone. The system is designed to be cross-compatible across our experimental mini-helicopters, aircrafts and ground vehicles, and it is tailored to allow autonomous navigation and control for a variety of different research test cases. The expandable architecture allows not only scalability, but also flexibility to test manned-unmanned fleet cooperative algorithm designs at both hardware and software layer deployed on bus integrated flight management computers. The flight simulator is used for joint simulation of virtual manned and unmanned vehicles within a common airspace. This allows extensive hardware-in-the-loop testing capability of customized devices and algorithms in realistic test cases that require manned and unmanned vehicle coordinated flight trajectory planning.     

Integrated Devices for Non-Invasive Diagnostics

“Sample-in-answer-out” type integrated diagnostic devices have been widely recognized as the ultimate solution to simplify testing across healthcare systems. Such systems are equipped with advanced fluidic, mechanical, chemical, biological, and electronic components to handle patient samples without any manual steps therefore have the potential to accelerate intervention and improve patient outcomes. In this regard, the combination of integrated devices and non-invasive sampling has gained a substantial interest to further improve the comfort and safety of patients. In this Review, the pioneering developments in integrated diagnostics are covered and their potential in non-invasive sampling is discussed. The key properties of possible sample types are highlighted by addressing their relevance for the clinical practice. Last, the factors affecting the transition of integrated devices from academia to the market are identified by analyzing the technology readiness levels of selected examples and alternative remedies are explored to increase the rate of survival during this transition.     

The effect of different surface pretreatments on the bond strength of veneering resin to polyetheretherketone

The aim of this study was to investigate the effect of different surface pretreatment methods on the bond strength of veneering resin to polyetheretherketone (PEEK) based aesthetic frameworks. Five hundred and forty PEEK disks were fabricated and divided into 6 pretreatment groups (n = 90); (C) untreated control group, (B) airborne-particle abrasion, (S) silica coating, (L) etching with Er:YAG (erbium-doped yttrium aluminium garnet) laser, (LB) etching with Er:YAG laser and airborne-particle abrasion and (LS) etching with Er:YAG laser and silica coating. After topographical surface examinations, specimens were conditioned with adhesive and veneering resin was polymerized onto the PEEK specimens. Twenty-four hours after veneering, specimens were subjected to thermal aging. Afterwards, shear bond strength (SBS) tests were performed and the obtained data were analyzed with one-way ANOVA and Tukey test at a significance level of α = .05. Group B (1.58 ± 0.15 μm), Group L (1.79 ± 0.29 μm), Group LB (2.20 ± 0.23 μm) and Group LS (2.31 ± 0.52 μm) demonstrated significantly higher surface roughness (SR) values compared to Group C (1.03 ± 0.11 μm). Group B (10.97 ± 2.88 MPa), Group S (12.07 ± 2.82 MPa), Group LB (12.09 ± 2.08 MPa) and Group LS (13.14 ± 1.45 MPa) demonstrated significantly higher SBS values compared to Group C (6.35 ± 1.21 MPa). Airborne-particle abrasion, silica coating or their combined use with Er:YAG laser system establish durable bond between PEEK and resin; however, only Er:YAG laser treatment has no positive effect on resin-PEEK bond.     

Supercapacitor device performances of polycarbazole/graphene and polycarbazole/nanoclay/graphene nanocomposites

In this study, graphene oxide (GO) is chemically reacted with sodium borohydride (NaBH₄) to form reduced graphene oxide (rGO). rGO, polycarbazole (PCz)/rGO and PCz/nanoclay/rGO materials were obtained by chemical polymerisation method. These three materials were characterised by Fourier-transform infra-red spectroscopy-attenuated transmission reflectance, scanning electron microscopy, energy-dispersive X-ray analysis, cyclic voltammetry (CV), galvanostatic charge–discharge and electrochemical impedance spectroscopy. The PCz/nanoclay/rGO nanocomposite shows significantly improved capacitance (C_sp?=?187.78?F?g^?1) compared to that of PCz/rGO (C_sp?=?74.18?F?g^?1) and rGO (C_sp?=?20.78?F?g^?1) at the scan rate of 10?mV?s^?1 by CV method. The supercapacitor device performance results show high power density (P?=?1057.81?W?kg^?1) and energy density (E?=?1.7?Wh?kg^?1) obtained from Ragone plot for PCz/nanoclay/rGO material. Stability tests were also examined by the CV method for 1000 cycles.