Sharif Digital Repository

The present research examines the effects of UV radiation, moisture and elevated temperature on the mechanical properties of GFRP pultruded profiles. Flexural, compressive and tensile properties of different GFRP sections were studied after they were exposed for 1000, 1500, 2000 and 3000 h to UV radiation and water vapour condensation cycles. Mechanical tests, including three-point bending, compression and tension tests, SEM analyses, and statistical studies were conducted to gather comprehensive results. The results showed that the mechanical properties of various GFRP sections generally decreased with the duration of conditioning: however, the rate of the decrease that was only slight up... 

This article presents an investigation on the durability of different glass-fibre-reinforced polymer composites when subjected to harsh outdoor conditions, including freeze/thaw cycles, ultraviolet radiation and moisture, as well as when used with seawater sea-sand concrete for construction applications. To achieve this, the effects of a number of parameters, including the environment of exposure, exposure time, profile cross-sectional configuration and orientation of fibres, on the mechanical properties of different glass-fibre-reinforced polymer composites were studied. To investigate the degradation of the mechanical properties, three-point bending, compression and tension tests were... 

TiO2 is a promising photoanode material for photoelectrochemical (PEC) water splitting, but its severe bulk recombination of photogenerated carriers, sluggish oxygen evolution reaction (OER) kinetics and poor visible light response are the main bottleneck problems. Here, the carbon quantum dots (CQDs) modified anatase/rutile TiO2 photoanode (CQDs/A/R-TiO2) was designed by growth of anatase TiO2 nanothorns on rutile TiO2 nanorods and further surface modification of CQDs. The results revealed that the A/R-TiO2 heterojunction significantly suppressed the bulk recombination of photogenerated carriers. With further incorporation of CQDs into A/R-TiO2, dramatical improvement of OER kinetics and... 

In this study, an assessment of concrete compressive strength was conducted using an impulse excitation data-driven machine learning (ML) framework. The model was constructed upon a deep neural network and aided by the backpropagation method, ensuring a precise training process. In contrast to prior research, which mainly focused on mixture components, a meaningful relationship between physical parameters—resonant frequencies and elastic moduli—and compressive strength was established by our ML model. Remarkable performance was demonstrated, with a root mean square error value of 2.8MPa and a determination factor of 0.97. Through Pearson analysis, correlations between input features and... 

This article presents an investigation on the durability of different glass-fibre-reinforced polymer composites when subjected to harsh outdoor conditions, including freeze/thaw cycles, ultraviolet radiation and moisture, as well as when used with seawater sea-sand concrete for construction applications. To achieve this, the effects of a number of parameters, including the environment of exposure, exposure time, profile cross-sectional configuration and orientation of fibres, on the mechanical properties of different glass-fibre-reinforced polymer composites were studied. To investigate the degradation of the mechanical properties, three-point bending, compression and tension tests were... 

In this research, the mechanical properties of various glass fibre reinforced polymer (GFRP) pultruded profiles exposed to seawater sea sand concrete (SWSSC) and its combination with UV radiation and water vapour condensation were studied. The effect of different conditions, duration of conditioning, and the profile cross-section configuration on the mechanical properties were investigated. Three-point bending, tension, and compression tests were carried out to obtain the mechanical properties, including flexural, tensile and compressive strengths and tensile elastic modulus. Furthermore, in order to scrutiny the mechanisms and extent of damage, scanning electron microscopy (SEM) was carried... 

H2S and CO2 are the main impurities in raw natural gas, which needs to be purified before use. However, the comprehensive utilization of H2S and CO2 has been ignored. Herein, we proposed a fully resource-based method to convert toxic gas H2S and greenhouse gas CO2 synchronously into CO and elemental S by using a novel electrochemical reactor. The special designs include that, in the anodic chamber, H2S was oxidized rapidly to S based on the I−/I3− cyclic redox system to avoid anode passivation. On the other hand, in the cathodic chamber, CO2 was rapidly and selectively reduced to CO based on a porous carbon gas diffusion electrode (GDE) modified with polytetrafluoroethylene and cobalt... 

The treatment of refractory wastewater and energy utilization are challenging environmental issues. Carbonate as the most common anion abounds in the aquatic environment. Here, we proposed a novel method to degrade carbonate-containing wastewater and simultaneous electricity generation via the combined oxidation of CO3[rad]− and O2[rad]− radicals. The CO3[rad]− radical was produced by the photoelectrode of TiO2/Si photovoltaic cell with the rear Si photovoltaic cell providing external bias, and the O2[rad]− radical was produced from the generation of H2O2 on a gas diffusion electrode (GDE), and they were both further enhanced from the activation reaction of H2O2 with HCO3− electrolyte. The... 

Hydrogen sulfide (H2S) generated by natural gas exploitation is a dangerous and harmful gas that needs to be purified. Electrochemical Natural Gas Desulfurization offers a promising way for H2S purification and resource utilization in ambient conditions. However, poor energy efficiency and low resource value limit the prospective application in the industry. Herein, we propose a gas-liquid flow electrocatalysis system that couples H2S oxidation and O2 reduction processes to effectively recover sulfur and H2O2 with low energy consumption. Gas diffusion and mass transfer are accelerated by gas-liquid flow cells, which also significantly decrease the resistance. Besides, I-/I3- redox pairs... 

The present study is focused on the investigation of the absorption properties of the bi-layer absorber with different thickness and orientation approaches. Improvement in absorption exclusively depends on the various parameters as interfacial polarization, multiple reflections among layers, conduction loss, phase cancellations, and shape anisotropy, etc. By considering these parameters. Calcium titanate micro-cubes CaTiO3 (CTO) and polypyrrole nanotubes (PPy) nanocomposites were prepared and microwave absorption from single layer coaxial absorbers having M1 = CaTiO3+15 wt% polymer and M2 = CaTiO3+30 wt% polymer were determined. Different layer orientations and thicknesses of the bi-layer... 

The ongoing and rapid growth of atmospheric CO2 levels causes a crucial worldwide concern. Herein, an efficient electrocatalyst has been introduced for electrochemical CO2 reduction reaction (CO2RR) to address the stability issue of ZIF-67. The catalyst consists of gold and silver nanostructures electrodeposited on the surface of a cobalt-based metal-organic framework (Au-Ag@ZIF-67). The uniform distribution of the Au-Ag alloy without any agglomeration on ZIF-67 was confirmed through microscopic observations. After 13.3 h of CO2RR, the specific surface area of Au-Ag@ZIF-67 slightly decreased, whereas that of ZIF-67 declined drastically, indicating excellent structural stability of the Au-Ag... 

Urea is a major source of nitrogen pollution in domestic sewage and its denitrification is difficult since it is very likely to be converted into ammonia or nitrate instead of expected N2. Herein, we propose an exhaustive denitrification method for urea via the oxidation of amine/ammonia-N with chlorine oxide radical, which induced from a bi-functional RuO2//WO3 anode, and the highly selective reduction of nitrate-N on cathode in photoelectrochemical cell (PEC). Under illumination, the WO3 photoanode side promotes the quantities hydroxyl and reactive chlorine radical, and these radicals are immediately combined to stronger chlorine oxide radical by RuO2 side, which obviously enhances the... 

The petroleum industry suffers from reservoir souring phenomena, which has negative impacts on production facilities, health, and environment. Injection of incompatible water into the reservoir (waterflooding), which is considered as an enhanced oil recovery (EOR) method, is one of the most common causes of reservoir souring. In general, injected brine, especially seawater, contains high amounts of sulfate ion (SO42−). A high concentration of sulfate in the presence of sulfate-reducing bacteria (SRB) leads to the microbial reservoir souring. During this phenomenon, sulfide, specifically hydrogen sulfide gas (H2S) appears in the producing fluid of the reservoir. In this paper, a coupled... 

The liver plays a complex role in metabolism and detoxification, and better tools are needed to understand its function and to develop liver-targeted therapies. In this study, we establish a mechanobiological model of liver transport and hepatocyte biology to elucidate the metabolism of urea and albumin, the production/detoxification of ammonia, and consumption of oxygen and nutrients. Since hepatocellular shear stress (SS) can influence the enzymatic activities of liver, the effect of SS on the urea and albumin synthesis are empirically modeled through the mechanotransduction mechanisms. The results demonstrate that the rheology and dynamics of the sinusoid flow can significantly affect... 

A new efficient catalytic system was investigated for the epoxidation of various olefins by cis-dioxo-bis[2-(2′-hydroxyphenyl)-oxazolinato]molybdenum(VI), cis-[MoO2(phox)2], and TBHP as oxidizing agent. Using this system as catalyst for the oxidation of aliphatic substrates at 80 °C gives the epoxide as the sole product with yields up to 100% and turnover frequency up to 5000 h-1. The efficiency of the catalyst is strongly influenced by the nature of solvent, reaction time and temperature, and a significant increase in the epoxide yields is observed in higher temperatures and longer reaction times. © 2009 Elsevier B.V  

Implementation of effective cancer treatment strategies requires consideration of how the spatiotemporal heterogeneities within the tumor microenvironment (TME) influence tumor progression and treatment response. Here, we developed a multi-scale three-dimensional mathematical model of the TME to simulate tumor growth and angiogenesis and then employed the model to evaluate an array of single and combination therapy approaches. Treatments included maximum tolerated dose or metronomic (i.e., frequent low doses) scheduling of anti-cancer drugs combined with anti-angiogenic therapy. The results show that metronomic therapy normalizes the tumor vasculature to improve drug delivery, modulates... 

Ostracism has been recognized as conceptually and empirically distinct from harassment. Drawing from theory and research that suggests that employees have a strong need to belong in their organizations, we examine the comparative frequency and impact of ostracism and harassment in organizations across three field studies. Study 1 finds that a wide range of employees perceive ostracism, compared with harassment, to be more socially acceptable, less psychologically harmful, and less likely to be prohibited in their organization. Study 2 surveyed employees from a variety of organizations to test our theory that ostracism is actually a more harmful workplace experience than harassment.... 

This work presents an innovative design for a flow-through dielectrophoretic cell sorting based on silicon bulk microelectrodes featuring sidewall undercuts. The microelectrodes are configured into an interdigitated array with digits extending across the flow chamber at an oblique angle against the flow stream. Target cells under dielectrophoretic forces and hydrodynamic drag can slide along the digits to a dedicated outlet. The design has been showcased for continuous-flow sorting of viable and non-viable mammalian cells, achieving a throughput of 16,600 cells/min, an order of magnitude higher than those reported for existing continuous-flow cell sorting designs using thin-film or... 

The search for efficient chemotherapy drugs and other anti-cancer treatments would benefit from a deeper understanding of the tumor microenvironment (TME) and its role in tumor progression. Because in vivo experimental methods are unable to isolate or control individual factors of the TME and in vitro models often do not include all the contributing factors, some questions are best addressed with systems biology mathematical models. In this work, we present a new fully-coupled, agent-based, multi-scale mathematical model of tumor growth, angiogenesis and metabolism that includes important aspects of the TME spanning subcellular-, cellular- and tissue-level scales. The mathematical model is... 

Sets of rosettes of stress probes have been performed on Hostun sand in a flexible boundary true triaxial apparatus. These have shown the effect of stress history on the local distortional stiffness of the sand. Histories have included isotropic compression, and deviatoric paths with increasingly complex shapes. These tests were performed and interpreted against a background of kinematic hardening and bounding surface plasticity, using stress response envelopes to reveal evolving distortional stiffness. Use of response envelopes to study volumetric stiffness appears to be less helpful but the phase transformation surfaces that can be extracted seem somewhat independent of recent stress...