Fuzzy adaptive anisotropic filter for medical images

Abstract: An adaptive anisotropic diffusion filter for images is proposed in this paper. First, the gradient of an image was calculated by a novel fuzzy‐rule‐based gradient operator. Accordingly, the centre of gravity of a histogram of the gradient image was estimated and it was assigned as an edge threshold. In conventional anisotropic filters, the conduction coefficients have to be selected by an operator. However, in this study, the centre of gravity of the histogram was assigned as the conduction coefficient of the anisotropic filter. Consequently, an adaptive anisotropic image filter which automatically sets its conduction coefficient without user intervention was developed. The image filter achieved was tested with various medical images.     

Lithium Accommodation in a Redox‐Active Covalent Triazine Framework for High Areal Capacity and Fast‐Charging Lithium‐Ion Batteries

The synthesis of a new type of redox‐active covalent triazine framework (rCTF) material, which is promising as an anode for Li‐ion batteries, is reported. After activation, it has a capacity up to ≈1190 mAh g^?1 at 0.5C with a current density of 300 mA g^?1 and a high cycling stability of over 1000 discharge/charge cycles with a stable Coulombic efficiency in an rCTF/Li half‐cell. This rCTF has a high rate performance, and at a charging rate of 20C with a current density of 12 A g^?1 and it functions well for over 1000 discharge/charge cycles with a reversible capacity of over 500 mAh g^?1. By electrochemical analysis and theoretical calculations, it is found that its lithium‐storage mechanism involves multi‐electron redox‐reactions at anthraquinone, triazine, and benzene rings by the accommodation of Li. The structural features and progressively increased structural disorder of the rCTF increase the kinetics of infiltration and significantly shortens the activation period, yielding fast‐charging Li‐ion half and full cells even at a high capacity loading.     

Automatic detection of respiratory arrests in OSA patients using PPG and machine learning techniques

Obstructive sleep apnea is a syndrome which is characterized by the decrease in air flow or respiratory arrest depending on upper respiratory tract obstructions recurring during sleep and often observed with the decrease in the oxygen saturation. The aim of this study was to determine the connection between the respiratory arrests and the photoplethysmography (PPG) signal in obstructive sleep apnea patients. Determination of this connection is important for the suggestion of using a new signal in diagnosis of the disease. Thirty-four time-domain features were extracted from the PPG signal in the study. The relation between these features and respiratory arrests was statistically investigated. The Mann–Whitney U test was applied to reveal whether this relation was incidental or statistically significant, and 32 out of 34 features were found statistically significant. After this stage, the features of the PPG signal were classified with k-nearest neighbors classification algorithm, radial basis function neural network, probabilistic neural network, multilayer feedforward neural network (MLFFNN) and ensemble classification method. The output of the classifiers was considered as apnea and control (normal). When the classifier results were compared, the best performance was obtained with MLFFNN. Test accuracy rate is 97.07 % and kappa value is 0.93 for MLFFNN. It has been concluded with the results obtained that respiratory arrests can be recognized through the PPG signal and the PPG signal can be used for the diagnosis of OSA.

     

An empirical model for parameters affecting energy consumption in boron removal from boron-containing wastewaters by electrocoagulation

In this study, it was investigated parameters affecting energy consumption in boron removal from boron containing wastewaters prepared synthetically, via electrocoagulation method. The solution pH, initial boron concentration, dose of supporting electrolyte, current density and temperature of solution were selected as experimental parameters affecting energy consumption. The obtained experimental results showed that boron removal efficiency reached up to 99% under optimum conditions, in which solution pH was 8.0, current density 6.0 mA/cm(2), initial boron concentration 100mg/L and solution temperature 293 K. The current density was an important parameter affecting energy consumption too. High current density applied to electrocoagulation cell increased energy consumption. Increasing solution temperature caused to decrease energy consumption that high temperature decreased potential applied under constant current density. That increasing initial boron concentration and dose of supporting electrolyte caused to increase specific conductivity of solution decreased energy consumption. As a result, it was seen that energy consumption for boron removal via electrocoagulation method could be minimized at optimum conditions. An empirical model was predicted by statistically. Experimentally obtained values were fitted with values predicted from empirical model being as following; [formula in text]. Unfortunately, the conditions obtained for optimum boron removal were not the conditions obtained for minimum energy consumption. It was determined that support electrolyte must be used for increase boron removal and decrease electrical energy consumption.     

Selective transport of cobalt (II) from ammoniacal solutions containing cobalt (II) and nickel (II) by emulsion liquid membranes using 8-hydroxyquinoline

The selective transport of cobalt (II) from ammoniacal solutions containing nickel (II) and cobalt (II) by emulsion liquid membranes (ELMs) using 8-hydroxyquinoline (8-HQ) as extractant has been presented. Membrane solution consists of a diluent (kerosene), a surfactant (ECA 4360J), and an extractant (8-HQ). Very dilute sulphuric solution buffered at pH 5.0 has been used as a stripping solution. The ammoniacal feed solution pH was adjusted to 9.0 with hydrochloric acid. The important variables governing the permeation of cobalt (II) have been studied. These variables are membrane composition, pH of the feed solution, cobalt (II) and nickel (II) concentrations of the feed solution, stirring speed, surfactant concentration, extractant concentration, complexing agent concentration and pH of the stripping solution, and phase ratio. After the optimum conditions had been determined, it was possible to selectively transport 95.0% of cobalt (II) from ammoniacal feed solution containing Co²⁺ and Ni²⁺ ions. The separation factors of cobalt (II) with respect to nickel (II), based on initial feed concentration, have experimentally found to be of as high as 31 for equimolar Co(II)–Ni(II) feed solution.     

Tl-208, Pb-212, Bi-212, Ra-226 and Ac-228 adsorption onto polyhydroxyethylmethacrylate-bentonite composite

The adsorption of naturally occurring radionuclides (²⁰⁸Tl⁺, ²¹²Pb²⁺, ²²⁶Ra²⁺, ²¹²Bi³⁺ and ²²⁸Ac³⁺) onto Polyhydroxyethylmethacrylate-bentonite (PHEMA-B) composite was investigated. Experimentally obtained isotherms were evaluated with reference to Langmuir, Freundlich and Dubinin-Radushkevich (DR) models. The adsorption isotherms were L type of Giles classification proving that PHEMA-B had a high affinity adsorbent for the studied radionuclides. The Langmuir adsorption capacities (X_L) were in the order of ²²⁶Ra (2.8 MBq kg⁻¹)>²¹²Bi (0.4 MBq kg⁻¹)>²¹²Pb (0.3 MBq kg⁻¹)>²²⁸Ac and ²⁰⁸Tl (0.2 MBq kg⁻¹). The adsorption process was physical via complex formation after proton exchanger for which the adsorption energies obtained from DR model was evidence. The enthalpy and entropy changes were positive and the negative free enthalpy change was proof for the spontaneity of adsorption. The reusability tests for PHEMA-B for five uses demonstrated that the adsorbent could be reused after complete recovery of the loaded radionuclide ions by 1 M HCl. The chemical structure of the composite did not change after the reuses and storage foregoing.     

Chiral recognition of proteins having L-histidine residues on the surface with lanthanide ion complex incorporated-molecularly imprinted fluorescent nanoparticles

In this study, lanthanide ion complex incorporated molecularly imprinted fluorescent nanoparticles were synthesized. A combination of three novel approaches was applied for the purpose. First, lanthanide ions [Terbium(III)] were complexed with N-methacryloyl-L-histidine (MAH), polymerizable derivative of L-histidine amino acid, in order to incorporate the complex directly into the polymeric backbone. At the second stage, L-histidine molecules imprinted nanoparticles were utilized instead of whole protein imprinting in order to avoid whole drawbacks such as fragility, complexity, denaturation tendency, and conformation dependency. At the third stage following the first two steps mentioned above, imprinted L-histidine was coordinated with cupric ions [Cu(II)] to conduct the study under mild conditions. Then, molecularly imprinted fluorescent nanoparticles synthesized were used for L-histidine adsorption from aqueous solution to optimize conditions for adsorption and fluorimetric detection. Finally, usability of nanoparticles was investigated for chiral biorecognition using stereoisomer, D-histidine, racemic mixture, D,L-histidine, proteins with surface L-histidine residue, lysozyme, cytochrome C, or without ribonuclease A. The results revealed that the proposed polymerization strategy could make significant contribution to the solution of chronic problems of fluorescent component introduction into polymers. Additionally, the fluorescent nanoparticles reported here could be used for selective separation and fluorescent monitoring purposes.     

Electrical resistivity of porcelain bodies with natural zeolite addition

In this study, the effect of natural zeolite addition on the electrical properties of porcelain bodies was investigated. Clinoptilolite, which is a type of natural zeolite, was added partially or fully in replacement of quartz in selected electro-porcelain compositions. Samples were fired in an electric furnace with a heating rate of 10 °C/min at 1200 and 1250 °C with a period of 60 min. The electrical resistance measurements of samples were performed at 50, 200, 400 and 600 °C. It was shown that the resistivity of samples increased at 50 °C temperature after zeolite addition, while it was decreasing after zeolite addition at higher temperatures. At the same time, it was recognized that the resistivity of samples depends on sintering temperature. The activation energy of electrical resistivity of samples was found to be in the range of 0.79–0.87 eV.     

Energy analysis and modeling of a solar assisted house heating system with a heat pump and an underground energy storage tank

An analytical model is presented and analyzed to predict the long term performance of a solar assisted house heating system with a heat pump and an underground spherical thermal energy storage tank. The system under investigation consists of a house, a heat pump, solar collectors and a storage tank. The present analytical model is based on a proper coupling of the individual energy models for the house, the heat pump, useful solar energy gain, and the transient heat transfer problem for the thermal energy storage tank. The transient heat transfer problem outside the energy storage tank is solved using a similarity transformation and Duhamel’s superposition principle. A computer code based on the present model is used to compute the performance parameters for the system under investigation. Results from the present study indicate that an operational time span of 5–7 years will be necessary before the system under investigation can attain an annually periodic operating condition. Results also indicate a decrease in the annually minimum value of the storage tank temperature with a decrease in the energy storage tank size and/or solar collector area.     

Necklace‐like Nitrogen‐Doped Tubular Carbon 3D Frameworks for Electrochemical Energy Storage

The design and synthesis of a necklace‐like nitrogen‐doped tubular carbon (NTC) are presented by growing microporous polyhedral ZIF‐8 particles and a uniform layer of ZIF‐8 on sacrificial ZnO tetrapods (ZTPs). Oxygen vacancies together with defect regions on the surface of the ZTPs result in the formation of ZIF‐8 polyhedra in conjunction with a very thin shell. This necklace‐like NTC structure has a high N content, very large surface area, ultrahigh microporosity, and quite high electrical conductivity. NTC‐based symmetrical supercapacitor and zinc‐ion capacitor (ZIC) devices are fabricated and their electrochemical performance is measured. The NTC supercapacitor shows an ultrahigh rate capability (up to 2000 mV s^?1) and promising cycle life, retaining 91.5% of its initial performance after 50 000 galvanostatic charge–discharge cycles. An aqueous ZIC, constructed using the NTC, has a specific capacitance of 341.2 F g^?1 at a current density of 0.1 A g^?1 and an energy density of 189.6 Wh kg^?1 with a 2.0‐V voltage window, respectively. The outstanding performance is attributed to the NTC high N‐doping content, a continuous “polyhedral 3D hollow” architecture and the highly porous microtubular arms exhibiting very high surface area.