Analysing legal status of electronic agents in contracting through interactive websites: comparative study of American,English and EU laws developing Iranian legal system

In the modern world, electronic communications play a significant role in national and international electronic transactions. This issue has forced all legal systems to face up to many emerging legal problems in the context of electronic communications, such as the legal status of electronic agents in contracting electronically. Regarding the legal validity of e-contracts made through interactive websites, the legal status of electronic agents which play an important role in this process is questionable to see whether they are akin to real agents in the physical world or they are only a mere tool of communication. The current article tries to analyse this question by criticising a number of theories and some others based on the technical nature of the Internet, the traditional legal rules and principles and the UNCITRAL regulations on e-commerce and also the statues of American, English and EU laws on e-commerce to develop Iranian legal system.     

Role of Energy Loss on Discharge Characteristics of Sluice Gates

A theoretical method was used to derive an equation for the discharge coefficient of sluice gates in rectangular channels under orifice-flow (both free and submerged) conditions. The proposed equation allows for the effects of energy dissipation between the upstream section of the gate and the vena contracta. The hydraulic energy loss in the upstream pool is attributable to the induced turbulence by the recirculating region and to the growth of bottom boundary layer. For the submerged-flow condition, turbulent shear-layer entrainment is also responsible for the energy loss. This energy loss is introduced into the equations through a coefficient k that has been conventionally assumed to be negligible. Experimental data from the literature were used to validate the equation, which showed good agreement with the measured values. It is also shown that the magnitude of the energy-loss factor is a function of the geometry of the gate and can modify the discharge coefficient. An equation for the distinguishing condition between free and submerged flows is also presented. The new equations can be used to predict the performance of sluice gates with different edge shapes under free- and submerged-flow situations.     

Exploratory Study of Submerged Hydraulic Jumps with Blocks

A preliminary study on submerged jumps with baffle walls and blocks downstream of a sluice gate was conducted. Two series of experiments were carried out on baffle walls and baffle blocks. The momentum equation was utilized to derive a relation for the drag coefficient that was validated by the experimental data of the baffle wall series. The baffle block series consisted of five Froude numbers and a range of submergence factors with one configuration of baffle blocks. The inlet depth factor was found to be a function of the submergence and Froude number. It was observed that the energy dissipation efficiency was a function of submergence with the maximum efficiency being in excess of that of the corresponding free jump.     

First and second law analysis of an ejector expansion Joule–Thomson cryogenic refrigeration cycle

In this paper, a combined first and second law approach is applied to study an ejector expansion Joule–Thomson cryogenic refrigeration cycle. The effects of the evaporator temperature, ejector pressure ratio and compressor function on the coefficient of performance (COP), exergy destruction and the exergetic efficiency have been investigated. The present study has been conducted for the evaporator and compressor temperature in the range of 75–135 and 270–330 K, respectively. The ejector pressure ratio is varied from 1.5 to 5.5. Simulation results show that COP and exergy efficiency increase with increasing evaporator temperature and ejector pressure ratio. In addition, it was found that the increase in the compressor temperature leads to the reduction in the first and second law efficiencies. Copyright © 2010 John Wiley & Sons, Ltd.     

Neural computations in modelling of CO2 capture from Gas stream emissions by Sodium Glycinate solution

The present contribution was performed in order to predict CO₂ loading capacity in aqueous sodium glycinate as a novel class of green solution under wide operating range using radial basis function artificial neural network (RBFANN). The predicted CO₂ loading capacity values were in brilliant agreement with those corresponding experimental values. The estimated values of MSE and R-squared were 0.00045 and 0.997, respectively. Accordingly, statistical and graphical analyses confirm satisfactory prediction of our proposed model.     

ECG changes associated with spontaneous left-sided pneumothorax

A patient with chronic obstructive pulmonary disease had a 100% pneumothorax on the left side associated with marked ECG changes. The changes occurring in this situation can be confusing. Because of the high prevalence of coronary heart disease in patients presenting with left-sided chest pain, an ECG usually is obtained to rule out acute myocardial infarction, in many instances even before history taking, physical examination, or chest x-ray study is done. Therefore, familiarity with the ECG manifestations of left-sided penumothorax is necessary to avoid delay in establishing the diagnosis and in beginning therapy.     

A new model for estimation of the thermal conductivity of polymer/clay nanocomposites

High density polyethylene– and polypropylene–clay nanocomposites are synthesized by melt blending, in which polyethylene glycol and polypropylene glycol are used as compatibilizers to increase the space of galleries. The morphology properties of nanocomposites are explored by X‐ray diffraction and transition electron microscopy. The thermal conductivity coefficient (K) of nanocomposites is also measured along with the thermal stability. A conventional model based on developed Maxwell‐Garnett formula is also established to predict the thermal conductivity of polymer/clay nanocomposites with clay loading. Morphology results indicate that two intercalated and exfoliated structures are formed. The established model satisfactorily predicts the K values of nanocomposites for low range of clay content. Thermogravimetric analysis shows remarkable thermal stability of nanocomposites with 10 wt % of clay content. The deviation of our model from experimental result for 10 wt % of clay can be attributed to the intercalated structure of layered silicates into the matrices. Although the K values do not considerably increase in 5 wt % with respect to the increase occurs for 10 wt % of clay, but it increases about 28 and 37% at 50°C for high density polyethylene– and polypropylene–clay nanocomposites, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Direct Sunlight Catalytic Decomposition of Organic Pollutants via Sm- and Ce-Doped BiFeO3 Nanopowder Synthesized by a Rapid Combustion Technique

In the development of photocatalytic processes towards waste water treatment, we have been long faced three foremost obstacles, including catalyst mass production, photon-energy cost and finally catalyst separation process after the treatment. In this study, such problems were addressed through the development of samarium and cerium-doped BiFeO₃ (BFO) nanoparticles (NPs) (Bi_xRE_xFeO₃; RE?=?Sm, Ce, x?=?0.00, 0.01, 0.03, 0.05;) employing a rapid solution combustion synthesis (SCS). This technique is greatly capable of large scale nanopowder production at low temperature. In the SCS procedure, different amount of oxidant-to-fuel (glycine-to-nitrate ion, Gly/NO₃^?) were investigated (Gly/NO₃^??=?0.2, 0.3, 0.37, 0.56, and 0.8). Moreover, a catalytic sunlight irradiation was employed to study the effect of Sm and Ce dopant contents on the photodegradation of benzene and methyl orange (MO) in the aqueous solution. The as-synthesized catalysts were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), UV–Visible diffuse reflectance spectroscopy (UV–Vis DRS) and Brunauer–Emmett–Teller (BET)/Barrett-Joyner Halenda (BJH) techniques. The band gap energy of BFO decreaed from 2.14 to 2.06 eV with the increase of Sm³⁺ contents while it increased up to 2.22 eV in the case of Ce-doped BFO. The solar decomposition of the organic pollutants demonstrated the superior performance of Bi_1-xSm_xFeO₃ photocatalyst rather than using cerium in the BFO crystalline structure which is attributed to the increased surface area and visible light harvesting.

Graphic Abstract

     

Stability and thermal conductivity of nanofluids of tin dioxide synthesized via microwave-induced combustion route

SnO₂ nanofluids were prepared by dispersing tin dioxide nanoparticles in deionized (DI) water as a base fluid. 4–5 nm tin dioxide crystals were synthesized via chloride solution combustion synthesis (CSCS) using SnCl₄ and sorbitol as a novel precursor and the fuel, respectively. Ammonium nitrate was also used as the combustion aid. The molar ratio of sorbitol plus ammonium nitrate to SnCl₄ was set at unity; whereas, the molar ratio of sorbitol-to-ammonium nitrate divided by that of stoichiometric value (Φ) was varied in the range of 0.5–1.4 in order to find the optimum values of specific surface area for the CSCS technique. Transition electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and Brunauer–Emmet–Teller (BET) techniques were employed for the characterization of the nanoparticles. Since SnO₂ nanoparticles form clusters within fluids, the fluids were ultrasonicated to improve the dispersion and stability of the nanoparticles. The colloidal stability of the SnO₂ nanofluids was quantitatively characterized by UV–vis spectrophotometric measurements. The results of the UV–vis experiments indicate higher dispersion together with enhanced stability for the nanofluid prepared by SnO₂ nanoparticles synthesized at Φ = 1.0. After 500 h sedimentation time, the relative concentration of the nanofluid with the highest stability is remained at around 77% of the initial concentration of the fluid.A transient hot-wire apparatus was used to measure the thermal conductivities of the nanofluids. In addition, the effects of pH and temperature on the thermal conductivity were also investigated. At 353 K, for the nanofluid prepared by SnO₂ nanoparticles synthesized at Φ = 1.0 at a weight fraction of 0.024%, thermal conductivity is enhanced up to about 8.7%, with an optimal pH = 8.