Single Element System Research Articles

Evaluating a 3D Ultrasound Imaging Resolution of Single Transmitter/Receiver with Coding Mask by Extracting Phase Information.

We are currently investigating the ultrasound imaging of a sensor that consists of a randomized encoding mask attached to a single lead zirconate titanate (PZT) oscillator for a puncture microscope application. The proposed model was conducted using a finite element method (FEM) simulator. To increase the number of measurements required by a single element system that affects its resolution, the transducer was rotated at different angles. The image was constructed by solving a linear equation of the image model resulting in a poor quality. In a previous work, the phase information was extracted from the echo signal to improve the image quality. This study proposes a strategy by integrating the weighted frequency subbands compound and a super-resolution technique to enhance the resolution in range and lateral direction. The image performance with different methods was also evaluated using the experimental data. The results indicate that better image resolution and speckle suppression were obtained by applying the proposed method.

Coexistence of Robust Edge States and Superconductivity in Few-Layer Stanene.

High-quality stanene films have been actively pursued for realizing not only quantum spin Hall edge states without backscattering, but also intrinsic superconductivity, two central ingredients that may further endow the systems to host topological superconductivity. Yet to date, convincing evidence of topological edge states in stanene remains to be seen, let alone the coexistence of these two ingredients, owing to the bottleneck of growing high-quality stanene films. Here we fabricate one- to five-layer stanene films on the Bi(111) substrate and observe the robust edge states using scanning tunneling microscopy/spectroscopy. We also measure distinct superconducting gaps on different-layered stanene films. Our first-principles calculations further show that hydrogen passivation plays a decisive role as a surfactant in improving the quality of the stanene films, while the Bi substrate endows the films with nontrivial topology. The coexistence of nontrivial topology and intrinsic superconductivity renders the system a promising candidate to become the simplest topological superconductor based on a single-element system.

Comparison Between Commercial and Synthesized Fe3O4 Nanoparticles for Removal of Heavy Metal Contaminants in Wastewater

Wastewater polluted with harmful heavy metal presently becomes a crucial environmental issue throughout the world. In this study, commercial and synthesized Fe3O4 nanoparticles were functioned to remove lead, nickel and cadmium ions in single element system. Experimental conditions including pH, contact time and metal ion concentrations were tested. The isothermal equilibrium for single component system was favorable and the maximum uptake of lead, nickel and cadmium ions adsorbed on commercial Fe3O4 were 35.3, 5.18 and 18.16 mg/g respectively while 31.5, 4.36 and 20.56 mg/g on synthesized one at optimum pH 6 for an hour of equilibrium contact time. The isotherm data resulted from both adsorbents fitted well with Freundlich model. The experiments demonstrates that the performance of synthesized nanosorbent which is economically convenient to be used, approaches the effectiveness of commercial Fe3O4. Therefore, prepared nanosorbent form was taken as practical adsorbent and utilized in binary and ternary systems to show the competition of metal contaminants. Results indicated that lead ions had rapid affinity to be sorbed on the nanoparticles while nickel solute had slow attraction. XRF X-ray fluorescence, TEM Transmission electron microscope, FTIR Fourier transfer infrared and XRD X-ray diffraction were also carried out to identify and demonstrate the properties of both nanosorbents.

Subsequent separation and selective extraction of thorium (IV), iron (III), zirconium (IV) and cerium (III) from aqueous sulfate medium

Regarding to their presence as an important constituent in some ores such as monazite, this work aims for selective solvent extraction of thorium (IV), zirconium (IV), iron (III) and cerium (III) from aqueous sulfate medium using different basic and acidic extractants. To elucidate the extractability of these elements, different effective parameters were studied such as contact time, pH value, extractant concentration and the diluents type. In a single element system, Th (IV) was extracted by the primary amines (octylamine and tert.octylamine) and the acidic extractnts [di-(2-ethylhexyl) phosphoric acid (D2EHPA) and (bis(2,4,4-trimethyl pentyl) phosphinic acid (Cyanex 272))]. Moreover, secondary amine (N-methylaniline) is effective for Fe (III) extraction while, the primary amines are suitable for Zr (IV) extraction. Ce (III) can be extracted with the primary amines and D2EHPA. In a mixed elements system, Th (IV) was extracted firstly with Cyanex 272 (65 %) atpH1 followed by the extraction of Fe(III) with N-methylaniline (95 %), then Zr (IV) was precipitated atpH2.5 (84 %) whileCe(III) remains in the final aqueous phase.

Removal of selected anions by raw halloysite and smectite clay

The structure of clay minerals is made up from tetrahedral and octahedral sheets, which can be stacked in different ways, forming 1:1, 2:1 and 2:1:1 layers. Halloysite, which belongs to the kaolin group, is composed of 1:1 layers while smectite group minerals exhibit 2:1 dioctahedral layered structure. The most important feature of these minerals is the presence of numerous active centers on their surface and/or in the interlayer space, which allows them to attract and exchange ions from aqueous solutions. These makes them perfect candidates which could be used for the purification of wastewaters from harmful ions (Bhattacharyya & Gupta 2008; Lee & Tiwari 2012). The aim of this work was to examine the sorption capacity of natural halloysite and smectite clay towards P(V), As(V) and Cr(VI). Two samples used in the research came from Polish deposits. Natural halloysite (H) was obtained from Dunino deposit, while smectite clay (SC) was obtained from Belchatow Lignine Mine where it forms an overburden cover. For the both raw samples the XRD patterns and FTIR spectra were collected. The sorption of P(V), As(V) and Cr(VI) was conducted as a function of anions concentration in the range from 0.05 to 50 mmol/L for initial pH 5 in a single-element system. The suspension of H or SC and an adequate solution (solid/solution ratio: 20 g/L) was shaken for 24 h at 25°C. Afterwards the anions concentration in the supernatant solution was measured using colorimetric methods. The P(V) and As(V) concentration was determined with molybdenum blue method, while Cr(VI) concentration was measured with diphenylcarbazide method. The XRD pattern of the H sample showed a basal peak at 7.20 A, which confirms the presence of dehydrated halloysite-(7 A). In turn, the SC exhibited a peak centered at ~12.5 A with an asymmetric profile starting from ~15.0 A. Such reflection suggests the presence of smectite which has both Na + and Ca 2+ cations in its interlayer space. The peaks at 4.26 A and 3.34 A are associated with quartz. The IR spectra of the H showed bands characteristic for kaolin group minerals related to the OH-stretching region (3700-3620 cm -1 ), vibrations of water molecules (~1630 cm -1 ) and bands assigned to stretching and bending vibrations of aluminosilicate framework (1200-400 cm -1 ). The IR spectrum of SC shows bands characteristic for smectite minerals i.e. 3623 cm -1 band attributed to OH hydroxyl located inside the 2:1 layer and a broad band centered at ~3400 cm -1 due to interlayer water surrounding cations. Also the structural vibrations of the 2:1 layer may be observed in the 1200-400 cm -1 region. The results of the experiment indicated that the sorption capacity of the H sample and the SC sample were relatively high. The amount of removed P(V) was the highest for both materials, where the sorption was respectively equal to: 201 and 256 mmol/kg. The sorption capacity of As(V) for the H was equal to 168 mmol/kg, while it was significantly lower on the SC (96 mmol/kg). In the case of H the Cr(VI) sorption reached only 36 mmol/kg and for the SC it was equal to 104 mmol/kg. In most cases the sorption isotherms were fitted to the Freundlich model. The only exception was for P(V) sorption on the H sample, which was better described by Langmuir model. The specific surface areas (S BET ) of the studied materials do not differ significantly: SC = 69.10 m 2 /g and H = 49.52 m 2 /g. The sorption centers that may attract anions in both, H and SC samples, were limited, because isomorphic substitutions in tetrahedral and/or octahedral sheets generate positively charged sites, which attract cations. It is believed that the mechanism responsible for the adsorption of anions on both materials is mainly surface complexation, which occurs at the crystals edges (Bradl 2004). The sorption capacity of the H and the SC was significantly lower than that reported for hydrotalcite-based anion-exchange materials (HTLc). For comparison, the sorption capacity towards P(V), As(V) and Cr(VI) on uncalcined HTLc was as follows: 498 mmol/kg (Kuzawa et al. 2006), 596 mmol/kg (Wu et al. 2013) and 314 mmol/kg (Alvarez-Ayuso & Nugteren 2005). Nevertheless, the examined mineral samples might be useful as sorbents for industrial wastewater treatment involving the removal of P(V) and As(V).

Kinetics of cadmium adsorption by smectite of Oued Tfal (Gafsa Basin)

Metals are quickly trapped in the soil and, in particular, in clays, which generally behave as reservoirs of these toxins. This retention is due to the adsorption properties and cation exchange capacity of clays, and we have to control this in order to limit their transport in the biosphere. This will be the subject of the study: the characterization of smectite of the Oued Tfal region in Gafsa (Tunisia) in one hand, and its application in the retention of cadmium through the new method of adsorption, and the study of factors affecting the adsorbability of the metal (nature of clay, ligands, initial concentration, etc.) on the other hand. The total surface area, determined by the methylene blue method, for the raw and purified samples was 556 and 783 m²/g, respectively. The adsorption kinetics depend on several parameters. The adsorption capacities of Cd(II) by raw and purified clays are 971 and 1,005 mg/g, respectively in the single element system, confirming the close correlation between the physicochemical properties of the adsorbent and its removal capacity. Cd(II)-clay obeys the Langmuir and Freundlich adsorption isotherms with high regression coefficients. The use of this adsorbent notably decreases the cost of treatment.

Third‐generation EUCLIDES concentrator results

ABSTRACTThis paper presents salient results from the third‐generation EUCLIDES linear photovoltaic concentrator, which was developed within the framework of the IDEOCONTE European project. There were two broad objectives for this project: firstly, to review and resolve the difficulties associated with previous prototypes (the Madrid prototype and the Tenerife plant), where the lack of qualification standards and quality control were identified as significant causes of failure under real‐world operation; and secondly, to optimise and commercialise the functionally effective components. During the development period, research activities focussed on cell encapsulation, the reliability of the system components, and the monitoring of field performance across three different test sites. The third‐generation EUCLIDES concentrator system has achieved an overall efficiency of 10%, which is similar to the efficiencies of previous EUCLIDES systems. The main third‐generation improvements relate to the industrialisation and improved reliability of single element system component. The expected system cost, for an annual production of 2 MW, is €3.70/Wp. However, the maximum allowable projected system cost under the Spanish feed‐in‐tariff of 2010 is €3.00/Wp. This will be very difficult to achieve with the current system efficiency. Copyright © 2011 John Wiley & Sons, Ltd.

Competitive adsorption of copper(II), cadmium(II), lead(II) and zinc(II) onto basic oxygen furnace slag

Polluted and contaminated water can often contain more than one heavy metal species. It is possible that the behavior of a particular metal species in a solution system will be affected by the presence of other metals. In this study, we have investigated the adsorption of Cd(II), Cu(II), Pb(II), and Zn(II) onto basic oxygen furnace slag (BOF slag) in single- and multi-element solution systems as a function of pH and concentration, in a background solution of 0.01 M NaNO 3. In adsorption edge experiments, the pH was varied from 2.0 to 13.0 with total metal concentration 0.84 mM in the single element system and 0.21 mM each of Cd(II), Cu(II), Pb(II), and Zn(II) in the multi-element system. The value of pH 50 (the pH at which 50% adsorption occurs) was found to follow the sequence Zn > Cu > Pb > Cd in single-element systems, but Pb > Cu > Zn > Cd in the multi-element system. Adsorption isotherms at pH 6.0 in the multi-element systems showed that there is competition among various metals for adsorption sites on BOF slag. The adsorption and potentiometric titrations data for various slag–metal systems were modeled using an extended constant-capacitance surface complexation model that assumed an ion-exchange process below pH 6.5 and the formation of inner-sphere surface complexes at higher pH. Inner-sphere complexation was more dominant for the Cu(II), Pb(II) and Zn(II) systems.

Visible Light Communication with LED Traffic Lights Using 2-Dimensional Image Sensor

We propose a new receiving method for an information-providing system that uses LED-based traffic lights as the transmitter. We analyzed the improvements obtained when 2-dimentional image sensor replaced the conventional single-element photodiode. First, we discuss the maximum receiver's field of view (FOV) when using the 2-dimentional image sensor at a particular focal length. We analyzed the best vertical inclination for both lanes and quantified the improvements in terms of the enhancement of received signal-noise ratio (SNR) when different numbers of pixels were applied. Our results indicate that using more pixels increases the received SNR and the service area becomes wider compared to the conventional single-element system. Consequently, receivable information within the service area also increased. We also found that the optimum number of pixels to accomplish a reliable communication system is 50 × 50 because performance degradation occured with a larger number of pixels.

An atomistic analysis of the interface mobility in a massive transformation

A new multi-lattice kinetic Monte Carlo method has been used for an atomistic study on the interpretation of the interface mobility parameter for a massive face-centred cubic (fcc) to body-centred cubic (bcc) transformation in a single element system. For lateral growth of bcc in a system with an fcc(1 1 1)//bcc(1 1 0) and fcc[1 1 2 ¯ ]//bcc[0 0 1 ¯ ] interface orientation the overall activation energy for the interface mobility parameter is governed by energetically unfavourable atomic jumps. The atoms on the fcc lattice often cannot jump directly to bcc lattice sites because neighbouring atoms block the empty bcc sites. By single unfavourable jumps and by groups of unfavourable jumps a path from fcc to bcc is created. The necessity of these unfavourable jumps leads to an overall activation energy considerably larger than the activation energy barrier for a single atomic jump.

Competitive adsorption behavior of heavy metals on kaolinite

Polluted and contaminated soils can often contain more than one heavy metal species. It is possible that the behavior of a particular metal species in a soil system will be affected by the presence of other metals. In this study we have investigated the adsorption of Cd(II), Cu(II), Pb(II), and Zn(II) onto kaolinite in single- and multi-element systems as a function of pH and concentration, in a background solution of 0.01 M NaNO 3. In adsorption edge experiments, the pH was varied from 3.5 to 10.0 with total metal concentration 133.3 μM in the single-element system and 33.3 μM each of Cd(II), Cu(II), Pb(II), and Zn(II) in the multi-element system. The value of pH 50 (the pH at which 50% adsorption occurs) was found to follow the sequence Cu < Zn < Pb < Cd in single-element systems, but Pb < Cu < Zn < Cd in the multi-element system. Adsorption isotherms at pH 6.0 in the multi-element systems showed that there is competition among various metals for adsorption sites on kaolinite. The adsorption and potentiometric titrations data for various kaolinite–metal systems were modeled using an extended constant-capacitance surface complexation model that assumed an ion-exchange process below pH 7.0 and the formation of inner-sphere surface complexes at higher pH. Inner-sphere complexation was more dominant for the Cu(II) and Pb(II) systems.

Simple Model for Earthquake Response Studies of Torsionally Coupled Buildings

Simple models defined only in terms of overall system properties are developed to approximate the response of one-story buildings. A system with several resisting elements may be idealized as a single element system with the following properties: several parameters in the linearly elastic range of behavior are the same as for the multi-element system; and a single yield surface, circular in the normalized coordiante system, with yield shear and torque defined in terms of the corresponding properties of the multi-element system. The response of a single-element system defined in this manner is approximately representative of the inelastic response of a large class of multi-element systems. Consequently, the variety of building properties and plan layouts encountered in practice, which are too numerous for explicit consideration in studies of earthquake response ot torsionally coupled buildings, can be effectively handled by a single element model.

Performance of Electrically Small Array Receiving Systems in the Presence of Noise

The performance of broad band electrically small beamed receiving arrays operating in the high-frequency band (3 to 30 MHz) and in a random noise environment is studied. The concepts of system noise figure (SNF) and signal-to-noise ratio improvement factor (SNIF) are proposed as criteria for comparing one array antenna receiving system to any reference antenna system when the conditions of operation are defined. Graphical representations of SNIF for the two- and four-element antenna systems versus a single-element system are presented. SNIF is shown to depend on the geometry of the array, on the phasing network, and on the ratio of atmospheric noise power to internal system noise power.