A compact tri‐band microwave resonator for ethanol gas detection

This article presents the design, simulation, fabrication, and testing of a compact two‐port microwave resonator coated with nanomaterials for ethanol gas sensing applications. The proposed gas sensor consists of a transmission line loaded with three triangular split ring resonators for ethanol detection at three frequency bands viz. 2.2, 4.6, and 6.3 GHz. The transmission line has all‐pass characteristics in which band gaps are introduced using three split ring resonators. The TiO₂ and ZnO nanorods are used as sensitive layers for the proposed sensing application. The nanorods, which are grown on a glass substrate of thickness 1 mm, are loaded on to the two‐port microwave resonator making the device sensitive to ethanol. The microwave behavior of the sensor is analyzed using the scattering parameters. The absorption of the ethanol gas causes frequency detuning which is used to analyze the presence of ethanol and its concentration. From the experiments, it is understood that there is an increase in the frequency shift with an increase in the concentration of ethanol gas. The sensing device with ZnO as a sensitive layer showed a higher average sensitivity of 2.35 compared to TiO₂ whose average sensitivity is 1.29.     

Analysis of conditions favourable for small vertical axis wind turbines between building passages in urban areas of Sweden

This paper presents the analysis of installing the vertical axis wind turbines between the building passages on an island in Stockholm, Sweden. Based on the idea of wind speed amplification due to the venture effect in passages, practical measurements were carried out to study the wind profile for a range of passage widths in parallel building passages. Highest increment in wind speed was observed in building passages located on the periphery of sland as wind enters from free field. Wind mapping was performed in the island to choose the most favourable location to install the vertical axis wind turbines (VAWT). Using the annual wind speed data for location and measured amplification factor, energy potential of the street was calculated. This analysis verified that small vertical axis wind turbines can be installed in the passage centre line provided that enough space is provided for traffic and passengers.     

Supercritical Impregnation of Active Components into Polymers for Food Packaging Applications

Supercritical impregnation is one of the novel technologies exploited for incorporation of active components into packaging material. This technique uses carbon dioxide as solvent to incorporate the active components in the polymeric matrix. The major advantages of using supercritical carbon dioxide as a solvent rely on the possibility to operate under mild temperature and so to process with thermo-sensitive active components. This technique permits the impregnation of diverse natural and synthetic polymers which is the main advantage of this process. This review covers recent developments in the application of supercritical impregnation technology for incorporation of active components in polymers for food packaging applications.     

Densities,ultrasonic speeds,refractive indices,and COSMO analysis for binary mixtures of dichloromethane with acetone and dimethylsulfoxide at T = (298.15, 303.15, and 308.15) K

Experimental densities (ρ), ultrasonic speeds (u), and refractive indices (n_D) of binary mixtures of dichloromethane (DCM) with acetone (ACT) and dimethylsulfoxide (DMSO) were measured over the whole composition range at T?=?298.15, 303.15, and 308.15?K. From the experimental data, excess molar volume (V^E), deviations in isentropic compressibility (Δk_s), deviations in intermolecular free length (ΔL_f), deviations in refractive index (Δn_D), and deviations in ultrasonic speed (Δu) were calculated. Moreover, the Benson–Kiyohara theory was applied to the binary mixtures to obtain the theoretical Δk_s values. The COSMO calculations depending on density functional theory were utilized to estimate the σ-profiles for the DCM, ACT, and DMSO. The interpreted σ-profile trends were found supportive with the experimental findings. Applicability of different empirical and semi-empirical relations of refractive index data were tested against the measured results, and good agreement has been obtained. The possible results of intermolecular molecular interactions among mixture components were interpreted.     

A review of molecular interactions in organic binary mixtures

The intention of this review article is to review the knowledge about interactions in organic binary liquid mixtures. Molecular interactions in organic binary liquid mixtures are interesting due to their extensive use in many fields of solution chemistry. The thermodynamics of component molecules present in various systems interacting are particularly interesting because they display fantastic results. Studies of different organic liquid mixtures represent the different modes of interactions prevailing in the component molecules. The number of parameters required describing the properties of a given class of mixtures increases sharply with the number of segment types involved. In recent years, the theoretical and experimental investigations of interactions between unlike molecules have been conveniently carried out using excess thermodynamic functions. The properties of liquid mixtures depend on the forces between molecules and on the nature and volume of these molecules, and change with the composition of the mixtures. This change, in turn, is reflected in the thermodynamic properties of the mixtures. The influence of significant contributions of a chemical, physical and geometrical nature that change excess thermodynamic properties is considered and explained in detail.     

Study of Micellization of Sodium Dodecyl Sulfate in Non-Aqueous Media Containing Lauric Acid and Dimethylsulfoxide

Interactions between dimethylsulfoxide (DMSO), lauric acid (LA) and anionic surfactant, sodium dodecyl sulfate (SDS) in non‐aqueous media have been studied in detail using conductometric, volumetric, and ultrasonic speed techniques. Conductivities, densities and ultrasonic speeds of 1 × 10^?3 to 11 × 10^?3 m SDS solutions in a mixture of LA (0.10 m) and DMSO between 298.15 and 313.15 K have been measured. The experimental data have been correlated against temperature and concentration of SDS using standard relations. The critical micelle concentration (CMC) values have been determined by using different methods like conductance, density and ultrasonic speed. All the methods yielded identical CMC values. The measured data were used to calculate various useful thermodynamic parameters like standard free energy, , enthalpy, , and entropy, , of micelle formation. From the density data of the surfactant, the change of the apparent molar volume upon micellization has been calculated. Density and ultrasonic speed data were used to evaluate the apparent molar adiabatic compressibility for the micelle of the surfactant at different temperatures over a wide concentration range.     

Environmental impacts of desalination on the ecology of Lake Urmia

Lake Urmia, the second largest hypersaline lake by area in the world, has fluctuated in salinity over time, but in recent years, it has reached a maximum of 340 g/L. The lake is the main habitat for the endemic Iranian brine shrimp, Artemia urmiana, and is a protected aquatic environment. Efforts have been made by the Iranian government to enhance the diversity of its wildlife. One approach has been to look for a method to reduce the salt content of the lake. We investigate the feasibility of this by first considering the water chemistry of Lake Urmia and then the various technologies used to extract salt from marine and brackish waters. Average concentrations of Na, Mg, K, Ca, Cl, SO₄, and HCO₃ were 125 g/L, 11.3 g/L, 2.63 g/L, 0.55 g/L, 216 g/L, 22.4 g/L, and 1.38 g/L, respectively, and cations and anions were balanced, However, Lake Urmia waters have a ‘very high’ salinity hazard and a high sodium adsorption ratio (SAR). Moreover, the saturation index (SI) for each of the major cations was greater than zero, indicating that the water in Lake Urmia is supersaturated, and precipitation is likely. The extraction of available salts from the lake for the use in petrochemical industries is economically feasible. However, technologies based on removing salts by distillation or reverse osmosis and then using this fresh water to dilute lake salinity are problematic. A better strategy would be better to allow more fresh water to reach the lake rather than creating fresh water through reverse osmosis and distillations processes. While concerns have been raised about the salinity tolerance of A.urmiana, it has successfully tolerated various salinity ranges from 166 to 340 g/L, and so the species is not threatened, unless the lake desiccates. Because the lake is saturated with salts, it seems unlikely that salinity could increase much higher.     

Synthesis and characterization of a thermally stable strongly acidic Cd(II) ion selective composite cation-exchanger: Polyaniline Ce(IV) molybdate

A polymer supported organic-inorganic composite and strongly acidic cation-exchanger polyaniline Ce(IV) molybdate was chemically synthesized and demonstrated to be an excellent ion-exchange material due to its high selectivity for Cd(II), thermal stability and fast elution of an exchangeable H⁺ ion. The material was characterized for its ion exchange properties to study its cation-exchange behavior. Cd(II) selectivity depends upon the distribution coefficient in several solvent systems. The selectivity of this material varied depending upon its composition and the composition of the eluting solvent. Its selectivity was examined and some important binary separations such as Cd(II)-Pb(II), Cd(II)-Hg(II), Cd(II)-Zn(II) and Cd(II)-Ni(II) were also achieved. The physico-chemical properties of the material were also studied using C, H, N elemental analysis, ICP-MS, FTIR, TGA-DTA, X-ray and SEM studies.     

Fabrication and electrical characterization of p-Cu2O/n-ZnO heterojunction

The conducting metal oxide (ZnO, Cu2O) films were used for fabrication of p-n heterojunction by rf sputtering and electrodeposition techniques respectively. The as synthesized films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV spectroscopy and electrical techniques. The electrical properties of the p-Cu2O/n-ZnO heterojunction were examined using the current-voltage measurements. The current-voltage (I-V) result showed that potential barrier was higher than the turn-on voltage, which was attributed to the presence of the interface defect states. The PN junction parameters such as ideality factor, barrier height, and series resistance were determined using conventional forward bias current-voltage characteristics. The annealing of Cu2O increase the crystallinity size and which enhance the photo current from 1.6 mA/cm2 to 3.7 mA/cm2. The annealing of respective film resulted in a decrease of these parameters with an increase in efficiency of solar cell from 0.14% to 0.3% at 350 degrees C.     

Organic–Inorganic Composite Material Polyaniline Ce(IV) molybdate: Thermal and Room Temperature Electrical Conductivity Measurement Studies

An electrically conducting ‘organic–inorganic’ composite material polyaniline Ce(IV) molybdate was prepared by incorporating electrically conducting polymer, i.e., polyaniline into inorganic precipitate of polyvalent metal acid salts i.e., Ce(IV) molybdate. The temperature dependence of electrical conductivity of this composite system with increasing temperatures was measured on compressed pellets by using a 4-in-line-probe dc electrical conductivity-measuring instrument. The values of conductivity lies in the semiconductor region, i.e., they are of the order of 10⁻⁵–10⁻² S cm⁻¹ and obey the Arrhenius equation. The thermal stability of this composite material in terms of dc electrical conductivity retention was studied under isothermal and cyclic techniques and electrical conductivity of composite was found to be sufficiently stable under ambient temperature conditions. The dependence of the electrical conductivity prepared with different concentrations of aniline monomers, on the concentration of conducting phases i.e., polyaniline was showed that electrical conductivity increase followed the percolation threshold.