Design and realization of an ultra‐low power sensing RF energy harvesting module with its RF and DC sub‐components

Herein, design, development, and analysis of ultra‐low power sensing energy harvesting modules and their subcomponents for ISM band applications have been studied with a holistic approach in an effort to achieve a feasible and high efficient RF energy harvesting performance. The complete harvester system designed and developed here consists of a zero‐bias RF energy rectifying antenna (rectenna), DC boost converters and energy storage super‐capacitors. Compared with the counterpart energy sources, the surrounding or transmitted wireless energy has low intensity which requires designs with high efficiency. To achieve a successful harvester performance, rectifier circuits with high sensitivity Schottky diodes and proper impedance matching circuits are designed. Dedicated RF signals at various levels from nanowatts to miliwatts are applied at the input of the rectenna and the measured input power versus the scavenged DC output voltage are tabulated. Furthermore, by connecting the rectifier to a high gain antenna and using a RF signal transmitter, the wireless RF power harvesting performance at 2.4 GHz was tested up to 5 m. The performance of the rectenna is analyzed for both low‐power detection and efficiencies. Impedance matching network is implemented to reduce the reflected input RF power, DC to DC converters are evaluated for their compatibility to the rectifiers, and super‐capacitor behaviors are investigated for their charging and storage capabilities. The measured results indicate that a wide operating power range with an ultra‐low power sensing and conversion performance have been achieved by optimizing the efficiency of the Schottky rectifier as low as ?50 dBm. The system can be used for battery free applications or expanding battery life for ultra‐low power electronics, such as; RFID, LoRa, Bluetooth, ZigBee, and low power remote sensor systems.     

Removal of basic dyes from aqueous solutions using starch‐graft‐acrylic acid copolymers

Graft copolymerization of acrylic acid (AA) onto starch was carried out with ceric ammonium nitrate as initiator under nitrogen atmosphere. The grafting percentages (GP%) of starch‐graft‐AA (St‐gr‐AA) copolymers were determined. When the AA molar concentrations were 0.3 and 0.5 mol/L, GP% of St‐gr‐AA copolymers were 10.5% (St‐gr‐AA‐1) and 14% (St‐gr‐AA‐2), respectively. St‐gr‐AA copolymers have been used for the adsorption of basic dye (Safranine T) from aqueous solutions. Effects of various parameters such as treatment time, initial pH of the solution (pH = 2–6), initial dye concentration (50– 500 mg/L), and GP% of starch graft copolymers were investigated.Basic dye removal capacities of the copolymers increase along with the augment of initial concentration of the adsorbate, GP% of the copolymers, and pH. The adsorption capacities for St‐gr‐AA‐1 and St‐gr‐AA‐2 reach 116.5 and 204 mg/g, respectively. Equilibrium adsorption data were obtained and fitted very well to Freundlich model. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis and properties of radiation‐induced acrylamide–acrylic acid hydrogels

Acrylamide (AAm)/acrylic acid (AAc) hydrogels in the cylindirical form were prepared by γ‐irradiating binary systems of AAm/AAc with 2.6–20.0 kGy γ‐rays. The effect of the dose and relative amounts of AAc and pH on the swelling properties, diffusion behavior of water, diffusion coefficients, and network properties of hydrogel systems was investigated. The swelling capacities of AAm/AAc hydrogels were in the range of 1000–3000%, while poly(acrylamide) (PAAm) hydrogels swelled in the range of 450–700%. Water diffusion into hydrogels was found to be non‐Fickian‐type diffusion. Diffusion coefficients of AAm/AAc hydrogels were found between 0.79 × 10^?5 and 2.78 × 10^?5 cm² min^?1. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3570–3580, 2002     

An automated industrial conveyor belt system using image processing and hierarchical clustering for classifying marble slabs

Although there are many industrial machines used in marble industry, classification of marble slabs in terms of quality is generally performed by human experts. Due to economic losses of this rather subjective process, automatic and computerized methods are needed in order to obtain reproducible and objective results in classification. With the aim of remedying this insufficiency in marble industry, a new electro-mechanical system, which automatically classifies marble slabs while they are on a conveyor belt and groups them with the help of a control mechanism, is proposed. The developed system is composed of two parts: the software part acquires digital images of marble slabs, extracts several features using these images, and finally performs the classification using clustering methods. The hardware part is composed of a conveyor belt, a serial port communication system, pneumatic pistons, a programmable logic controller (PLC), and its control circuits, all employed together for grouping the marble slabs mechanically. Although similar studies exist, this paper proposes three novelties over the existing systems. Firstly, a new hierarchical clustering approach is introduced for quality classification without requiring a training set. Secondly, a new feature set based on morphological properties of marble surface images is proposed. Finally, an electro-mechanical system is designed for accomplishing the task of sorting out the classified marble slabs. In the literature, only a system with a labeling mechanism has been presented. Our system, on the other hand, comes with a complete conveyor belt acting as an element that links the production line with the proposed system. This allows the possibility of embedding the proposed system into the production line of a marble factory. It has been observed that although the performance of the developed system is not as high as neural network based systems that use training, it could still be employed in industry when there is no available training set of samples. With this advantage, it provides an increase in the quality control standards of marble slab classification, since marbles are classified with an objective and uniform-through-time criterion.     

Ceria supported manganese(0) nanoparticle catalysts for hydrogen generation from the hydrolysis of sodium borohydride

Herein we report for the first time the preparation and catalytic use of the ceria supported manganese(0) nanoparticles in hydrogen generation from the hydrolysis of sodium borohydride. They are in situ formed from the reduction of manganese(II) ions on the surface of ceria nanopowders during the catalytic hydrolysis of sodium borohydride in aqueous solution at room temperature. Manganese(0) nanoparticles are isolated from the reaction solution by centrifugation and characterized by a combination of analytical techniques. Nanoceria supported manganese(0) nanoparticles are highly active and long-lived catalysts providing a turnover frequency of 417 h^?1 and 45,000 turnovers in hydrogen generation from the hydrolysis of sodium borohydride at 25.0 ± 0.1 °C. They also have high durability as they retain 55% of their initial catalytic activity after the fifth cycle of hydrolysis providing a release of 4 equivalent H₂ gas per mol of sodium borohydride. The noticeable activity loss in successive runs of hydrolysis is attributed to the deactivation due to agglomeration. High activity and stability of ceria supported manganese(0) nanoparticles are ascribed to the unique nature of reducible cerium oxide. The formation of cerium(III) defects under catalytic conditions provides strong binding for the manganese(0) nanoparticles to oxide surface which makes the catalytic activity and stability favorable. Our report also includes the results of kinetic study of catalytic hydrolysis of sodium borohydride depending on the temperature, catalyst and substrate concentration.     

Occurrence of ochratoxin A in cereal-derived food products commonly consumed in Turkey

Ochratoxin A (OTA) is a mycotoxin that can be found in several food commodities including cereals, wine, coffee, cacao, spices or dried fruits, resulting in chronic human exposure. The aim of our study was to investigate the presence of OTA in widely consumed cereal-derived products commercialized in Turkey. A total of 142 samples were collected from different supermarkets and traditional bazaars in Istanbul during 2008-2010 years. The analytical methods used in our study involved the liquid/liquid extraction of OTA, immunoaffinity clean-up and high performance liquid chromatography determination with fluorescence detection. The frequencies of OTA contamination were 21.62%, 19.05% and 55.95% and the mean concentrations of positive samples were 0.32 μg/kg, 0.14 μg/kg, 0.41 μg/kg for breakfast cereals, cereal-based baby foods and tarhana samples, respectively. Our findings show that contamination levels of OTA in all cereal-derived products were lower than the permitted level by European Commission Regulation.     

An Analysis of Global Stability of Takagi–Sugeno Fuzzy Cohen–Grossberg Neural Networks with Time Delays

Neural Processing Letters - This paper deals with the problem of the global asymptotic stability of Takagi–Sugeno (T–S) fuzzy Cohen–Grossberg neural networks with multiple time...     

A review: Recent advances in sol-gel-derived hydroxyapatite nanocoatings for clinical applications

The prospect of modifying the surface properties of the substrate (or base) material to enhance its corrosion and wear resistance as well as its reliability, performance, and more importantly its bioactivity is made possible using nanocoatings. An effective technique of synthesizing high purity nanocoatings in addition to nanopowders and fibers is to utilize the sol-gel approach. It is an attractive and versatile method that can be carried out with relative ease. Ceramic coatings, such as hydroxyapatite (HAp), can be fabricated through chemical means from solutions and consequently complex shapes can be coated economically. Given the fact that mixing takes place on the atomic scale, one of the key advantages of the sol-gel technique is its capacity to produce homogeneous materials, and it has been shown that the mechanical properties of sol-gel coatings are enhanced due to the presence of nanocrystalline grain structures. This review covers a brief insight into the recent application of HAp nanocoatings derived from sol-gel technique.     

Determination of trace element contents of baby foods from Turkey

The levels of trace elements in different types of baby foods consumed in Turkey were determined by flame and graphite furnace atomic absorption spectrometry. Dry, wet and microwave digestion procedures were compared and the microwave digestion method was found to be the best. The accuracy of the method was ensured by using a standard reference material (NIST-SRM 8418 Wheat Gluten). The levels of elements in analyzed samples were found to be under legal limits. The range of the investigated elements were 0.52–4.38 μg/g, 0.22–7.20 μg/g, 1.02–67.5 μg/g, 0.92–37.2 μg/g, 0.12–0.32 μg/g, 2.02–68.8 μg/kg, 10.7–66.8 μg/kg, 0.05–10.3 μg/g, 2.67–25.4 μg/kg for Cu, Mn, Fe, Zn, Se, Cr, Al, Ni and Co, respectively.