Novel fabrication of PdCu nanostructures decorated on graphene as excellent electrocatalyst toward ethanol oxidation

In this study, the electrochemical reduction reaction of copper(II) formate on the graphene/glassy carbon electrode (G/GCE) surface in the HCl (5 wt.%) was employed for fabrication of the PdCu nanostructures by galvanic displacement reaction. This method has a number of advantages including being environmentally-friendly, simplicity, inexpensiveness and fast. The PdCu nanostructures decorated on the G/GCE were fabricated in two steps: (1) electrochemical reduction reaction of copper(II) formate to Cu on the G/GCE and (2) the galvanic replacement reaction between Cu and Pd²⁺ ions. The physical and electrochemical properties of as-prepared PdCu/G were investigated via Field Emission Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, Cyclic Voltammetry, Chronoamperometry, and Electrochemical Impedance Spectroscopy. The PdCu/G compositional effect on ethanol oxidation in alkaline media is investigated. The results were shown that the catalytic activity and durability of PdCu/G catalyst are superior to those of Pd/C electrocatalyst for ethanol oxidation. The PdCu/G increased the current density 6.2 times more than Pd/C with a 50 mv negative shift in onset potential for electrooxidation of ethanol. Besides, the novel PdCu/G catalyst exhibits large electrochemically active surface area, lower apparent activation energy, higher levels of stability, poisoning tolerance, and lower charge transfer resistance compared to the Pd/C for the oxidation of ethanol.     

A simple and fast method for the preparation of super active Pd/CNTs catalyst toward ethanol electrooxidation

For the first time, galvanic reduction by zinc sheet is used as a new strategy to prepare modified electrodes. In this work, glassy carbon electrode (GCE) was modified by decoration of Pd nanostructures on carbon nanotubes (Pd/CNTs). In this method, deposited PdCl₂ on CNTs was directly reduced to metallic Pd nanostructure using a zinc sheet in HCl (2% w/w) solution. This approach offers a number of advantages including being very fast, simple and green; and modified electrodes show high activity. The prepared catalyst is characterized by Field Emission Scanning Electron Microscopy, X-Ray Diffraction and energy-dispersive X-ray and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). In addition, electrochemical measurements show that the performance as well as the stability of the as-prepared catalyst for ethanol oxidation is outstanding. The Pd/CNTs catalyst shows higher mass current density, which is 7.9 times as high as that of commercial Pd/C.     

Synthesis of nanozeolite A from natural clinoptilolite and aluminum sulfate; Optimization of the method

The zeolite NaA was synthesized from natural clinoptilolite as Si source and aluminum sulfate or sodium aluminate as Al source. The use of aluminum sulfate for the synthesis of zeolite A has not been reported in the literature. This study presents as the first time a synthesis approach in which the low cost and available source is used to prepare zeolite NaA. These nano particles of zeolite were prepared at different conditions in autoclave and a mixer was designed specifically for this purpose. The synthesized zeolites were characterized by instrumental analysis methods, such as X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope (SEM), transmission electron microscope (TEM) and wet chemical analysis by atomic absorption spectroscopy (AAS). Cation exchange capacity (CEC) and loss on ignition (LOI) have been also measured on the prepared samples. The influences of different parameters such as reaction time, temperature, initial gel concentration, mechanical stirring and drying conditions on the improvement of the final products were experienced and the procedure for the efficient synthesis of zeolite NaA was optimized with available quality control tests. Solubility of clinoptilolite as the Si source in alkaline solutions was also investigated.     

A Homozygous Deep Intronic Variant Causes Von Willebrand Factor Deficiency and Lack of Endothelial-Specific Secretory Organelles,Weibel–Palade Bodies

A type 3 von Willebrand disease (VWD) index patient (IP) remains mutation-negative after completion of the conventional diagnostic analysis, including multiplex ligation-dependent probe amplification and sequencing of the promoter, exons, and flanking intronic regions of the VWF gene (VWF). In this study, we intended to elucidate causative mutation through next-generation sequencing (NGS) of the whole VWF (including complete intronic region), mRNA analysis, and study of the patient-derived endothelial colony-forming cells (ECFCs). The NGS revealed a variant in the intronic region of VWF (997 + 118 T > G in intron 8), for the first time. The bioinformatics assessments (e.g., SpliceAl) predicted this variant creates a new donor splice site (ss), which could outcompete the consensus 5′ donor ss at exon/intron 8. This would lead to an aberrant mRNA that contains a premature stop codon, targeting it to nonsense-mediated mRNA decay. The subsequent quantitative real-time PCR confirmed the virtual absence of VWF mRNA in IP ECFCs. Additionally, the IP ECFCs demonstrated a considerable reduction in VWF secretion (~6% of healthy donors), and they were devoid of endothelial-specific secretory organelles, Weibel–Palade bodies. Our findings underline the potential of NGS in conjunction with RNA analysis and patient-derived cell studies for genetic diagnosis of mutation-negative type 3 VWD patients.     

Particle Swarm Optimization for Automatic Calibration of Large Scale Water Quality Model (CE-QUAL-W2): Application to Karkheh Reservoir,Iran

An automatic calibration of water quality model is developed in this research. Automatic calibration as the process to determine the parameters appearing in the equations of a 2-dimensional, hydrodynamic, and water quality models (CE-QUAL-W2) is carried out with Particle Swarm technique as an optimization tool. In the calibration of the CE-QUAl-W2 model, evaporation as a significant parameter influences the thermal profile and water surface elevation in reservoir, simultaneously. Therefore to consider the simultaneous effects of the water temperature variations on water surface elevation in the reservoir, a multi objective technique is used to minimize the weighted sum of total deviations of temperature from field data at check points on monitoring days and those of water surface elevation on daily monitoring period. The proposed approach overcomes the high computational efforts required if a conventional calibration search technique was used, while retaining the quality of the final calibration results. The automatic calibration approach is applied in temperature and water budget calibration of Karkheh reservoir in Iran. Applying the proposed automatic calibration approach, shows the produced results by the CE-QUAL-W2 model with the calibrated coefficients agree closely with a set of field data.     

Sub-recoil-limit laser cooling via interacting dark-state resonances

We propose a laser cooling mechanism based on velocity-selective double-dark resonance that leads to a temperature significantly lower than the one-photon recoil limit. This mechanism benefits from sharp and high-contrast spectra which are induced by the two electromagnetically induced transparency windows due to the interacting dark-state resonances. It is theoretically demonstrated that four-level atoms illuminated by two counter-propagating probe beams and two additional beams directed perpendicularly to the other two exhibit new cooling effects; for red detuned probe lasers, atoms can be subject to a strong viscous force with an extremely small diffusion, characteristic of heating caused by the stochastic nature of spontaneous emission processes. By quantum mechanical simulations, we then find that the lowest temperature in EIT windows approaches 1?nK for the case of mercury. However, the different broadening mechanisms can destroy the cooling, so that the lowest temperature can increase to the recoil temperature.     

Natural frequency and critical speed determination of an axially moving viscoelastic beam

In this paper, the natural frequency and critical speed of an axially moving viscoelastic beam with clamped and simple supports are calculated analytically based on the Euler–Bernoulli and Timoshenko theories. The beam is incompressible in bulk and viscoelastic in shear, which obeys the linear standard solid model with material time derivative. The axial speed is characterized by a simple harmonic variation about a constant mean speed. By defining some dimensionless parameters, the governing equations are derived from the Newton’s second law. They contain two coupled partial differential equations with time depended coefficients. The straightforward method in perturbation theory is used to solve these equations. By considering the homogeneous equation, the natural frequencies are calculated. The critical speed is determined by a constant speed assumption. By a parametric study, the effects of mechanical and geometrical parameters on the natural frequency and critical speed are investigated.     

The PRODNET cooperative information management for industrial virtual enterprises

When designing an IT platform aimed at supporting industrial virtual enterprises (VEs), certain issues related to information management requirements become especially challenging, such as the physical distribution of data, the enterprise autonomy and privacy enforcement, access rights to shared information, and data visibility levels, among others. In the ESPRIT project PRODNET II, a federated database architecture was designed and implemented as the base support framework to effectively manage these issues associated with the sharing and exchange of information in the VE environment. In this paper, first the general information management requirements identified for the VE network in the PRODNET II project are described, and then the challenging design issues behind the development of the components of the federated information management system are presented.     

The impact of mobility models on the performance of P2P content discovery protocols over mobile ad hoc networks

One of the challenges over mobile ad-hoc networks is content discovery. P2P content discovery techniques including structured and unstructured can be employed in MANETs by considering its special characteristics and limitations. The most important characteristic of MANETs is the mobility of the nodes which creates a dynamic topology. A novel framework is presented to evaluate the effect of mobility and its models on the resource discovery. By using several metrics, this framework is capable of evaluating the effect of mobility on the underlay structure and subsequent changes on the overlay structure. The results obtained from extensive simulation, presented here, clarify the significant role of the mobility models on the performance of P2P content discovery protocols. These results are supported by mathematical analysis of content discovery protocols.     

Water Table Management to Improve Drainage Water Quality in Semiarid Climatic Conditions of Iran

A lysimeter study was conducted in the field in Karaj, Iran to investigate the effects of water table management on water quality of subsurface drainage effluents. Drain volumes, nitrate-N concentration, phosphorus concentration, and electrical conductivity of drain effluents were monitored during the growing seasons of alfalfa (Medicago scutellata). Totally 12 lysimeters consisted of four treatments were used in this study, of which nine of them were equipped with subirrigation (SI) and the other three with free drainage (FD) systems. Annual alfalfa (Medicago scutellata) was planted in all lysimeters. Water table levels were kept at 30 cm (SI30), 50 cm (SI50), and 70 cm (SI70) below the soil surface in SI-lysimeters and more than 100 cm below the soil surface in FD-lysimeters. The results of this 2-year study showed a significant reduction in nitrate-N concentrations in SI-lysimeters compared to FD-lysimeters. In 2005, the mean nitrate-N concentrations in drainage effluent were reduced by 84% in the SI30 and by 82% in the SI50, relative to FD. Similarly, in 2006, drain water depth and nitrate-N concentrations were significantly reduced relative to FD. The forage dry matter production from SI30 and SI50 were significantly higher than those from FD in both years. In 2006, the average of dry matter production was increased by 69 and 89% by the SI30 and SI50, respectively, relative to FD. The average electrical conductivity of drainage water was reduced in SI lysimeters compared to FD lysimeters that meet Iranian standard level (3 dS/m). There are no statistically significant differences in phosphorous concentration in drainage water of different treatments. Finally, the results of this 2-year study indicate that the water table management practices are economically and environmentally feasible in Iran in order to have a sustainable agriculture.