Co-doped graphene sheets as a novel adsorbent for hydrogen storage: DFT and DFT-D3 correction dispersion study

In this study, transition metals (TM) such as palladium (Pd) have been introduced on co-doped graphene and defect graphene sheets with nitrogen and boron ad-atoms to investigate the potentials of new adsorbents for hydrogen storage. The first principle studies using density functional theory (DFT) and DFT-D3 correction dispersion were undertaken to calculate the adsorption energy of hydrogen molecule on the graphene sheet. The results showed that applying Pd transition metal could enhance adsorption energy of hydrogen molecules towards pristine sheet. The main problem in applying transition metal on graphene sheets was concerned with clustering. However, the current defects in graphene sheets prevent clustering event. Our simulation results suggested that these defects reduced hydrogen adsorption and substitute dopants such as nitrogen and boron together on graphene sheets could improve the adsorption energy. Thus, two various forms of Pd decorated NB co-doped as hexagonal and double carbon vacancy (DCV) were introduced as new structures for hydrogen storage. A physical adsorption, which is appropriate for reversible hydrogen storage, was implemented for both novel adsorbents. In the two various forms of NB co-doped structures, DCV had the optimum adsorption behavior as adsorption energy level and density of state (DOS) phenomena. Moreover, the results of adsorption energy using DFT method were consistent with that of DFT-D3 correction dispersion and higher amounts of adsorption energy in DFT-D3 method were obtained. Finally, results introduced Pd decorated NB co-doped graphene sheets as a novel material for hydrogen storage.     

Exploring Adjacent Pentagons in Non-IPR and SW Defective Si60 and Si70 Silicon Fullerenes: a Computational Study

Silicon - We have applied DFT calculations to investigate the effect of the adjacent pentagons (APs) on the geometries, stabilities, and electronic structures of the non-IPR isomers of Si60 and...     

Preparation of superabsorbent composite based on acrylic acid-hydroxypropyl distarch phosphate and clinoptilolite for agricultural applications

Recently, using superabsorbent polymers (SAPs) are considered as a solution for reducing the water consumption particularly in agricultural applications. Presented here is the synthesis of a novel biocompatible SAP, utilizing for reducing the water consumption particularly in agricultural applications via graft copolymerization of hydroxypropyl distarch phosphate (HDP) based on tapioca starch with acrylic acid (AA), loading with clinoptilolite zeolites. A two-level factorial design of experiments, investigating the effect of the SAP composition on the water absorbency exhibited that the optimum SAP has the maximum water absorbencies of 1075 and 67 g g⁻¹ in distilled water and 0.9 wt % NaCl solution, respectively. The chemical structure of the best superabsorbent was characterized using Fourier transform infrared, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy analyses. The results revealed that AA was successfully grafted onto HDP and surface morphology of the superabsorbent was improved with incorporated clinoptilolite zeolites. In addition, the results of water absorption in different soil textures showed that within a first week after irrigation, the soil texture with 100% sand has the maximum water retention (69.6 g more than its control sample), as well as that with 50% sand, loses the absorbed moisture 49 days later than its control sample. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47365.     

Development and characterization of flexible antenna based on conductive metal pattern on polyester fabric

Current paper focuses on the development and characterization of flexible antenna based on conductive metal pattern on polyester fabric. The flexible fabric patch antenna was prepared by printing of metallic patterns on fabric textures through a multi-step process. The inkjet printing followed by electroless nickel plating methods were employed to coat different patch sizes and shapes with extremely high conductivity on insulated fabric. The scanning electron micrograph imaging technique confirms the formation of Ni nanoparticle with normal distribution and average size of 150 ± 20 nm. The EDAX analysis reveals more than 93%w/w Ni which supports the high four-point probe conductivity of 2500 ± 175 S/cm for antenna patterns. The X-ray diffraction pattern also indicates the amorphous nickel formation and randomly phosphorus atoms trapped between the nickel atoms. Also, the measured results evidence that the tensile strength of the textile Antenna shows an increase of 25.72% in the warp direction and 19.98% in the weft direction. Also the amount of flexural stiffness significantly improves and the wrinkles reduced after electroless plating. Also the antenna’s gain and bandwidth were studied by spectrum analyzer and the coated film surfaces. The largest printed patch antenna experienced a significant increase of about 1 kHz in bandwidth and ?3 dB increase in gain value compared to other antennas. Also, the rectangular shape antenna showed a peak value at bandwidth of 4.2 kHz and gain value of ?0.1 dB in comparison with spiral antenna.     

STUDY ON THE ACETYLENE HYDROGENATION PROCESS FOR ETHYLENE PRODUCTION: SIMULATION,MODIFICATION, AND OPTIMIZATION

In this study, an industrial acetylene hydrogenation unit is simulated utilizing three available kinetic models. The results are compared against six-day experimental data and the best model is selected. Effects of feed temperature and the amount of injected hydrogen on ethylene selectivity are also studied. According to the simulation results, the unit is not working under its optimum conditions. Furthermore, by reduction of the hydrogen flow rate to 52 kg/h, process selectivity is increased. In addition, a new approach is proposed to modify the hydrogenation process and reduce undesired by-products. In the simulation of the modified process, hydrogenation reactors temperature, hydrogen flow rate, and H-1/H-2 ratio were regulated as adjustable parameters for the process optimization. The simulation shows that ethylene selectivity increases by 12%, while acetylene concentration and hydrogenation reactor temperature remains within acceptable ranges. Such selectivity could be achieved at the hydrogen flow rate of 50 kg/h with H-1/H-2 ratio of 0.1/0.9.     

Thermodynamic modeling of PVTx properties for several water/hydrocarbon systems in near-critical and supercritical conditions

Both the equation of state-excess Gibbs energy (EoS/G ^E ) model and the cubic plus association (CPA) equation of state (EoS) are compared in this study with respect to their accuracy in the correlation of PVTx for systems such as water/methanol, water/ethanol, water/benzene, water/toluene, water/methane, water/n-butane, water/n-pentane, water/n-hexane, water/heptane, and water/octane, in supercritical conditions within temperature and pressure ranges of (573–698 K) and (7.0–276.0 MPa), respectively. In the proposed EoS/G ^E model, Peng-Robinson (PR) equation of state, linear combination Vidal-Michelsen (LCVM) and Wong-Sandler (WS) mixing rules in conjunction with UNIQUAC activity coefficient model were used. Correlation of both CPA and EoS/G ^E models was evaluated by comparing the results with the experimental data. Average absolute relative deviation (AARD) for WS, LCVM, and CPA was found to be 2.99, 11.11 and 5.14%, respectively, indicating better correlation of WS model with the experimental data.     

The effect of nitric acid,ethylenediamine, and diethanolamine modified polyaniline nanoparticles anode electrode in a microbial fuel cell

Anode materials are important in the power generation of microbial fuel cell. In this study, polyaniline was used as a conducting polymer anode in two chambers MFC. XPS and SEM were used for the characterization of functional groups of anode materials and the morphology. The power generation of microbial fuel cell was elevated by the modification of anode by nitric acid, ethylenediamine, and diethanolamine. The time that MFC reaches its maximum power generation was shortened by modification. Moreover the SEM photos prove that, it causes better attachment of microorganisms as biocatalysts on electrode surface. The best performance of among the MFCs with different anode electrodes, was the system working by polyaniline modified by ethylenediamine as that generated power of 136.2 mW/m² with a 21.3% Coulombic efficiency.     

An experimental investigation of pool boiling characteristics of alumina-water nanofluid over micro-/nanostructured surfaces

Abstract

Experiments were conducted to investigate the nucleate pool boiling heat transfer of pure water and alumina/water nanofluids on different micro- and nanostructured surfaces prepared via the thermal spray coating method. Results indicate that nanofluids boiling on all the test surfaces led to critical heat flux (CHF) values greater than that obtained for the base fluid (i.e., water). Higher roughness value, however, led to higher CHF values in boiling over the surfaces. Another finding of this study indicated that CHF values obtained with boiling on Cu-coated micro- and nanosurfaces were identical although the heat transfer coefficient (HTC) values obtained for boiling on the micro-structure surface were higher than those obtained for a nanostructured surface with almost the same roughness. A series of consecutive nanofluid boiling cycles were also performed on the aluminum-coated nanostructured surface. The CHF value obtained for water boiling on the surface undergoing repeated nanofluid boiling cycles was by 27% higher than that obtained for a clean surface although the relevant HTC values were nearly identical.     

Economic‐Statistical Design of Acceptance Control Chart

Acceptance control charts are effective tools to monitor capable processes in which the fraction of the produced nonconforming items is very low. In these charts, some controlled changes in the process mean are allowed, and the production of a specified number of defectives is tolerated. Designing these acceptance control charts by considering the cost of sampling, detecting, and investigating out‐of‐control signals as well as the probable correction of assignable cause(s) can result in economic advantages. Moreover, the statistical properties of the control charts can be satisfied. In this article, an economic‐statistical model is developed to design acceptance control charts. An illustrative example is used to compare the results of economic versus economic‐statistical design of the acceptance control charts. In addition, a comprehensive sensitivity analysis is conducted on the basis of the parameters of the model. Copyright © 2012 John Wiley & Sons, Ltd.