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Soil stabilization techniques have traditionally relied on cement or lime, yet there remains a significant knowledge gap regarding the mechanical behavior of soil treated with innovative materials. Addressing this gap, this study delves into the mechanical properties of soil stabilized with polyurethane (PU) foam, nano-silica, and basalt fiber. Through rigorous experimentation, unconfined compressive strength (UCS) and direct shear tests were conducted on reconstituted silica and calcareous samples, each treated with various combinations of these additives. A comprehensive examination of parameters such as additive content and curing time was undertaken to elucidate their effects. The results unveiled a noteworthy enhancement in UCS and shear strength parameters (cohesion and friction angle) with the incorporation of PU foam, nano-silica, or their amalgamation with fiber. Particularly striking was the superior performance observed with the combination of PU and basalt fiber, showcasing remarkable improvements in the mechanical behavior of both silica and calcareous sand, especially when considering shorter curing times. The synergistic effects of PU and basalt fiber proved instrumental in fortifying the soil's structural integrity against environmental challenges. Furthermore, it was consistently observed that calcareous samples exhibited elevated UCS, and shear strength values compared to their silica counterparts. This discrepancy underscores the inherent differences in mechanical behavior between these two types of sand, highlighting the need for tailored stabilization approaches. Moreover, the investigation delved into the failure patterns and microstructural changes within the stabilized samples, employing Scanning Electron Microscopy (SEM) for detailed analysis. This microscopic examination offered valuable insights into the efficacy of the stabilizing agents and their impact on the soil's mechanical properties. For instance, SEM imaging revealed significant bonding in fiber-reinforced samples, indicating enhanced load transfer mechanisms. Similarly, the presence of clusters of nano-silica particles adhering to sand particles showcased an improved cohesion within the stabilized soil. PU-stabilized samples, on the other hand, exhibited a cohesive layer enveloping sand particle, thereby enhancing interparticle connectivity and overall stability. The superior performance of PU over nano-silica was underscored by its ability to create a more cohesive matrix and foster stronger interparticle bonds, as evidenced by the SEM analysis. In conclusion, this study sheds light on the potential of innovative stabilization materials such as PU foam, nano-silica, and basalt fiber in bolstering the mechanical properties of soil. The findings not only offer valuable insights into the efficacy of these additives but also pave the way for the development of tailored soil stabilization techniques geared towards enhancing infrastructure resilience and sustainability.
 

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Recently, flexible and environmental-friendly aerogel blankets have attracted considerable attention. In this work, the novel silica aerogel/basalt blanket was prepared using basalt fibers via a two-step sol-gel process followed by an ambient drying method and immersing the basalt fiber layer into silica sol. The silica aerogel particles were characterized by FTIR, FE-SEM and nitrogen adsorption analysis. The morphology, hydrophobic properties and surface roughness of neat basalt fiber and its aerogel blanket were also investigated. The density if 0.34 g/cm³, the porosity of 85%, mean pore size of 7±1.5 nm and the surface area of 750 m²/g for the nanostructured silica aerogel particles are obtained. The formation of nanostructured silica aerogel particles on the surface of basalt fibers in the sol-gel process were efficiently occurred leading to a strong hydrophobicity the blanket samples (contact angle of 114°) compared to the hydrophilic neat basalt fibers. The surface roughness of basalt fiber in the blanket samples was increased due to the fiber surface coating with silica aerogel particles. Increasing the sol volume in the synthesis process increased the basalt surface roughness from 3.6μ to 11μ. 

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Presence of filler in the polymeric materials changes the mechanical, dynamic-mechanical, rheological properties and even the swelling behavior of rubber composite due to mechanisms such as hydrodynamics, polymer-filler and filler-filler interactions. Swelling in rubber composites directly affects the polymer chains, also can affect indirectly other structures in composites such as the filler network and reduce mechanical properties suddenly. In this study, the nitrile rubber-nanosilica composite containing different concentrations of modified nanosilica was prepared and the composite structure was studied through rheological, mechanical, dynamic-mechanical tests. Also it was found that the filler network containing over percolation threshold 13phr of filler concentration has a significant contribution to the mechanical properties of composites. To determine the swelling effect on the prepared composite structure, with different degrees of solubility were used. The mechanical properties of the samples were measured in equilibrium swelling state for each of the solvents The decrement of the mechanical properties between the dry samples and swelled ones containing 14.4, 20 and phr 6.25 silica in solvent with 15% toluene is significant. These intensive changes in mechanical properties that happen at the low degree of swelling are attributed to the removal of the filler network. Therefore, controlling the swelling of rubber parts in adjacent to the solvent, plays the fundamental role in their performance.

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In this study, three different size (100-300-500 µm) of the rubber powder (waste tire) were used in the formulation of epoxy- phenolic adhesive. Rubber powder was modified with grafting method by acrylamide monomer. In order to prevent any loss in properties such as modulus and strength of the adhesive, which is due to the addition of rubber powder to the adhesive, the micro particles of silica were used in formulation of epoxy- phenolic adhesive.  The experiment was designed by Taguchi method, and in the experiment, the effect of the composition of rubber powder, size of rubber powder, composition of silica filler and phenolic resin on mechanical and thermal properties of epoxy adhesives were investigated. To study the mechanical properties of adhesives and adhesion properties, dumbbell-shaped specimens and single edge lap bonds that have been made of metal (stainless steel) to composite (epoxy resin / carbon fiber) were prepared and subjected to tensile test. Thermal stability and interfacial interaction between epoxy and filler in adhesive formulation were explored by thermogravimetric analysis and Fourier transform infrared spectroscopy analyses, respectively.  Tensile test results showed that for lap- joint bonding with the addition of each factor in its optimal level into epoxy adhesive, strength, modulus and toughness increase by 7.5%, 27.56% and 114% respectively in comparison with  the samples bonded with the neat  epoxy adhesive. A significant increase was obtained in thermal stability for formulated adhesive samples compared with neat epoxy adhesive.
 
 

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In graded structure aerogels, change of pores diameter through the thickness affects the effective thermal conductivity. As the pores diameter is reversely correlated to the density, the effective thermal conductivity of aerogel is often normalized to the density and it is expressed as the B parameter. Lower values of B would be the optimum conditions for the resulting aerogel. The objective of this work is to simulate the heat transfer of the homogenous structures and to compare it with structures that pore diameter vary through the thickness. For this purpose, the structure characteristics and properties of silica aerogel along with the effect of coupling thermal conductivity have to be taken into consideration. Using the COMSOLMultiphysics®software, the heat transfer was modeled for a number of cases, including homogenous structures with minimum density (L), maximum density (H) and for an optimum structure (OPT) having a minimum value of the B parameter. The results were compared to thestructurally graded aerogels in which the density was varied in two fashions, from higher values to lower (HtL) and from lower to higher values (LtH). The change of temperature with time was tracked for all the cases. Results indicated that the minimum value of heat transfer was obtained for the structurally graded aerogel of the type of LtH (a 2-percent increase of efficiency for LtH when compared to the optimum structure (OPT)). Therefore, this structure introduce as the best candidate for producing a thermal insulator.

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is one of the most common improved oil recovery method in the world. High residual oil saturation at the end of this method is due to low macroscopic sweep efficiency and viscous fingering. It can be improved by the mobility control during polymer solution injection. In this study, by of silica/ the effect of it on IFT, viscosity, and was investigated. In addition, the performance of in high salinity water was studied by using nano particles. The zeta potential results show that the stability of polymer solution was enhanced in of nano particles in high salinity water condition. Also, the lowest IFT was obtained for contained 1 percent nano silica (18.34 ), and the most tendency to water wet conditions was provided for this concentration. In addition to, 1 percent nano silica/ has the best performance on formation water viscosity and improved the mobility ratio to 1.07, which it can increase the oil recovery.

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Research subject: In this research we studied the anti-corrosion properties of epoxy coating containing anti-corrosion pigment zinc phosphate with hydrophobic nano silica with different percentage also for determine the optimal conditions for preparation of nanocomposite Taguchi experimental design method was used.
 
Research approach: Anti-corrosion properties of epoxy coating under the influence of very important factors such as the percentage of nano silica, anticorrosive pigment and pigment to resin ratio according to model L9 taguchi method was studied and analyzed. Anti-corrosion properties of epoxy coatings were studied by electrochemical impedance spectroscopy test (EIS) in 3/5% NaCl aqueous solution and salt fog test (salt spray). To investigate the distribution of nano silica particles in epoxy resin were analyzed by transmion electron microscope (TEM) and scanning electron microscope (SEM). The results show that using from zinc phosphate and nano-silica was able to improve the corrosion resistances.
 
Main results:Results shows that addition of zinc phosphate and nano silica to epoxy resin caused a decrease in number of blisters and corrosion products after exposure to corrosion test based on the results in Nyquist and Bode plots, also the similarity in results was observed for the epoxy coating loaded according to the optimum conditions with 8% zinc phosphate, 3% nano silica and pigment to resin ratio of one according to salt spary. The significance levels of the experimental parameters, which indicate how the factors affect the compressive addition of zinc phosphate and nano silica to epoxy resin, were determined by using variance (Anova) method.

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Research subject: The rice husk is the coating on a rice grain and a by-product of the rice milling process. In this study, the extraction of amorphous silica from this agricultural residue by thermal as well as acid/thermal treatment method was studied.
Research approach: The process was designed as follows: after burning the paddy in the open field, the obtained ash was washed with acid followed by drying. Finally, the amorphous silica was obtained by placing the prepared powder in an electric furnace (acid/thermal treatment). Also, a sample of silica was produced by eliminating the acid treatment step (thermal treatment). Afterward, the obtained silica powder was employed in a conventional passenger radial tire belt formula instead of commercial precipitated one, and whole the physical-mechanical properties, including rubber-to-wire adhesion force, were studied under normal and aging conditions.
Main results: The results of the XRD demonstrated that the silica produced in both methods were amorphous. The XRF analysis also showed that the purity of amorphous silica were 98.6% and 93.9% for the sample produced by acid/heat treatment and the heat treatment, respectively. The results of the tire test showed that the rubber-to-wire adhesion decreased slightly under normal conditions in the presence of new silica samples, but the same property under the timed conditions for the new silica samples was better than commercial precipitated silica. Other properties of the rubber compound did not change significantly in the presence of new silica grades. As a result, it can be said that rice husk has a potential to produce suitable silica for use in blend of radial tire belt.

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Research subject:
As a low price biomass, rice husk is able to accumulate a large amount of silica in its texture. The process for extracting this silica is greener than the conventional ones. The present research addresses the effects of the different process parameters on amorphous silica extraction from rice husk through a precipitation method.
Research approach
In the extraction process, first the rice husk was burned in the open air and then turned into white ash in an electric furnace. This ash was converted into sodium silicate solution using NaOH, and finally the silica was precipitated from this solution by sulfuric acid. The effect of solid to solvent ratio, the duration of the alkaline dissolution step as well as the pH and temperature of acid precipitation step have been investigated. Moreover, a special application of the amorphous silica in rubber industry was also investigated.
Main results
The results showed that a low solid to solvent ratio at the alkaline dissolution stage as well as an acidic pH along with a high precipitation temperature are required to obtain the highest production efficiency and to obtain high purity amorphous silica. The purity and chemistry of obtained silica were quite similar to commercial sample in the rubber industry; however, the surface area and pore volume of obtained silica was less than the commercial one. It was also found that prolonging the alkali dissolution step slightly increases the production efficiency. The obtained silica exhibited very close performance to the commercial sample, in the rubber-to-fiber adhesion system (RFS). This indicates the high ability of precipitated silica to be replaced by commercial types, which are mainly produced by more cost-effective and less biocompatible processes.

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Research subject: This study demonstrates a synthetic strategy for the preparation of porous SiO₂ for adsorption applications using natural and waste materials from rice husks which are functionalized with polymer dendrimer molecules and surface amino groups as the source of biosilica and were investigated to remove divalent cadmium ions from aqueous solutions.
Research approach: Porous silica nanoparticles with a mean diameter of 45 nm were successfully fabricated from rice husk (RH) biomass via a multistep method. During the first step, sodium silicate is extracted from rice husks. Then, cetyltrimethylammonium bromide, HCl, and acetic acid were added to the sodium silicate solution, and the resulting mixture was sonicated. After the hydrothermal reaction, the collected samples were calcinated to obtain silica nanoparticles. These synthetic nanoparticles were identified using various techniques such as Fourier-transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, field emission scanning electron microscopy, nitrogen adsorption-desorption analysis and dynamic light scattering analysis. Then, the adsorption kinetics and the effects of synthetic nanoadsorbents dosage on the removal of divalent cadmium ions were investigated. The effect of contact time on cadmium adsorption and recyclability of adsorbent was also investigated.
Main results: The results show that there is no significant reduction in the performance and activity of this nanosorbent in the adsorption of metal ions after 6 times of recycling and reuse. The excellent performance of this nanosorbent in the removal of metal ions is due to its high porosity, active surface amine groups and high surface-to-volume ratio.

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Hypothesis: Because of the widespread use of rubbers in different industries, estimating the rubber material properties and its lifetime are very important in design procedure to assure the quality and safety of the rubber components. In this study, the properties and useful lifetime prediction of EPDM rubber parts used in the production of sealing gaskets and sealants for GRP pipes were investigated and the effect of adding silica nanoparticles as well as Si69 coupling agent on these characteristics was studied.

Methods: In this work, the samples were tested under accelerated aging conditions and aged in the temperature range of 25-90 °C until 60 days. Then time-temperature superposition was carried out on tensile test and compression set results using Williams Landel Ferry (WLF) model to estimate useful lifetime of the samples. Tensile test was conducted under ISO 12244 standard and compression set test was performed according to ISO 815 standard on rubber samples. Aging effect on samples with and without silica was analyzed with FTIR. In addition, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed to observe the dispersion condition of silica nanoparticles in EPDM samples.
 
Findings: According to obtained results, TEM images showed no sign of nanoparticles agglomeration within the samples due to presence of Si69 and SEM graphs depicted a uniform distribution of particles in the matrix. Using time-temperature superposition principle, the lifetime was estimated about 63 and 35 years at room temperature for the rubber samples with and without silica and Si69 coupling agent, respectively. It was observed that the presence of modified silica nanoparticles improves the mechanical and thermal properties of EPDM and also increases the useful lifetime of this elastomer.
 

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Aim Land use change (LUC) not only affects the plant and soil functional properties, but also influences soil nutrients efficiency. This research was carried out to examine the effect of grassland conversion to dry farming on the efficiency of bio-mineral nutrients in semi-arid loamy soils of northwestern Iran.
Materials & methods Animal manure (AM: 100 and 200 g. Kg^-1), useful micro-organisms (UMOs: 1 and 2%), superabsorbent polymers (SAP: 10 and 30 g. Kg^-1) and potassium nano-silicate (PNS: 500 and 1000 mg. Kg^-1) were used for grass Festuca ovina L. cultivated in grassland and dry farming soil at a completely randomized factorial design.
Findings Based on the results, LUC strongly affected the efficiency of soil nutrients especially PNS (P ≤0.01) where the highest and lowest effects of different nutrients were observed under dry farming and grassland, respectively. A maximum difference of 24.0%, 45.0% and 24.0% were observed in plant biomass, chlorophyll, moisture content, respectively, using 200 g. Kg^-1 AM and 30 g. Kg^-1 SAP in soil of grassland and dry farming. Also, maximum difference of 71.0% and 67.0% occurred at soil phosphorus and organic matter, respectively between grassland and dry farming.
Conclusion depending on the type and amount of fertilizer, convert the grasslands to rainfed areas significantly influence plant performance and soil improvement. Overall, due to the undisturbed soil, grasslands show a better performance than rainfed areas under any rehabilitation program.

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This article presents a transient model of a solar adsorption cooling system. A computer program is developed to simulate the operation of a two-bed silica gel- water adsorption cooling system as well as flat plate collectors and the hot water storage tank. This program is then utilized to simulate the performance of a sample solar adsorption cooling system used for cooling a set of rooms that comprises an area of 52 m2 located in Ahwaz city in Iran. The results include the temperature profiles of hot, cooling and chilled water in addition to adsorption/desorption beds, evaporator and condenser, collector hot water temperature, auxiliary heater fuel consumption and solar fraction of the system. Furthermore, the effect of the cycle time on COP (coefficient of performance), SCP (Specific Cooling Power), refrigeration capacity, fuel consumption and solar fraction is studied. The results show that the cycle time increases COP and SF of the cycle but decreases cooling capacity and supplementary heater fuel consumption.

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Abstract: The durability of concrete structures against corrosion due to high concentration of chloride ion is considered as a main concern in these kinds of structures in Persian Gulf area. However, increasing the initial temperature its effect on concrete microstructure can intensify this issue & severely increase the concrete corrosion rate. This article deals with the high initial temperature effect on chlorine ion penetration in concrete, particularly concretes consisted of silica fume. Evaluation of high initial temperature has been done by making samples in different temperature till initial setting & keeping in the same conditions in the environment temperature to simulate the environmental conditions of Persian Gulf. For this purpose, the changes of concrete micro structure due to initial temperature increase & its effect on concrete resistance properties against chloride ion penetration have been studied. In this paper, the influence of high initial temperature on chloride penetration and microstructure of concrete containing silica fume was investigated. Two different mixes at three different initial casting temperature (20-40°c) were studied: a control mix in which no cement replacement materials were added and a mix where cement was partially replaced 6% silica fume (by weight), at a constant water-to-binder ratio of 0.45 and a cement content of 400 kg/m3. High initial temperature casting was employed to simulate concrete temperature in Persian Gulf hot climate. The results show that chloride penetration at 40°c is directly related to increase in the porosity of the binder phase and the absorption of concrete. The Higher chloride penetration resistance was observed when cement is partially replaced with silica fume. From SEM result recognized silica fume particles make core sites to cement hydration, therefore make more consistency micro structure and decrease pore size distribution. It is concluded that increasing the initial temperature of the concrete in the time of casting & formation, leads to accelerating the hydration & therefore the heterogeneous distribution of products in the mixture. This phenomenon causes the bigger pores in the concrete structure by increasing the temperature and more space for chloride ion penetration. So, high casting and initial temperature leads to increasing chloride ion penetration & reduction of concrete resistance against corrosion. By adding silica fume to the mixture, size & the distribution of pores improve and the temperature increase effect on parameters of chloride penetration & corrosion decrease. Hence, the corrosion behavior (Chlorine ion penetration coefficient & electrical potential) of 40°c silica fume included specimen are improved than reference concrete.   Keywords: Initial Temperature, Corrosion, Chloride diffusion, Silica Fume

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  Active packaging is one of the innovative concepts in food packaging that has been used for controlling environmental parameters such as moisture content in the package. In this study the quality and quantity characteristics of button mushroom were investigated by color, maturity index, opening caps and weight loss after the storage at refrigerator temperature (5 ±2 ° C). The treatments included packaging film at two levels: (clear PVC box and stretch PVC), moisture absorber at four levels: and storage time at five levels: (0, 4, 8, 12 and 16 days). Four moisture absorber treatments were included: the first treatment containing silica gel 1.25 g, the secondary treatment silica gel 2.5 g, the third treatment only  spongy foam, the forth treatment  containing silica gel 1.25 g and spongy foam. The analyses showed that the stretch PVC in comparison to clear PVC films had the lowest open cap mushroom and weight loss. Silica gel (1.25g) treatment and only foam treatment with stretch PVC film had the lowest open cap. The sensorial evaluation showed there was no significant difference between treatments in terms of maturity index. In terms of cap color, judges preferred button mushrooms treatments by silica gel (1.25 g) with clear PVC box and Silica gel (1.25g) with stretch PVC treatments and there were significant differences between them and other treatments.  

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The indirect application of silver nanoparticles (AgNPs) in controlling the common fungal infection during the incubation period of Persian sturgeon -saprolegniasis - was investigated in this research. Filters containing 0.2%, 0.5% and 1% of AgNPs in two states without agent and with aminopropyltriethoxysilane (APTES) coupling agent along with the control treatment (without filter) were the treatments investigated in the present study. The results showed that in the first 48 hours of incubation, which corresponds to embryonic growth before the start of neurulation, despite the start of contaminating the water in the incubators with Saprolegnia fungus, fungal infection was not seen in any of the investigated treatments. The results of measuring the amount of silver released from the studied filters at the end of the first 12 hours of incubation showed that the amounts of silver released in the water in the treatments of 1% AgNP filters without APTES and with APTES were significantly higher than other filters containing AgNPs. This trend was repeated at the next sampling rounds (48 and 96 hours) with the difference that the release rate was significantly higher only in the 1% AgNP-APTES filter treatment. In the treatment of AgNP-APTES filters, the percentage of hatching showed a significant increase compared to the control filter treatment.

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This paper presents the experimental study on vibration characteristics of polymeric nanocomposites containing 1 weight percentage of mesoporous silica (MCM-41), Hydroxy Apatite(HA), the composite of MCM-41 and HA (MH) and carbon nanotube (CNT) as a fillers. Experimental results show that damping ratio and natural frequency increase in the neat PP, CNT/ PP, HA/ PP, MCM-41/ PP nanocomposites and MH/ PP hybrid nanocomposite specimens, respectively. In order to introduce the effect of foam agent in the vibration absorbing properties, foam agent is added to CNT/ PP and MH/ PP nanocomposits. The results show that foamed specimens have more damping capacity and lower natural frequency than unfoamed specimens. The maximum value of increasing the damping ratio and natural frequency of the MH/ PP hybrid nanocomposite than neat PP is 55.02 % and 34.05%, respectively. So, MH/ PP hybrid nanocomposite that is studied in this paper for the first time, can remove the reduction of unwanted vibrations of structures problems.

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This paper presents the influences of adding nano-silica on electrical resistivity of cement paste, because the electrical resistivity test is one of the non-destructive test in durability issues that can help us to assess the resistance of cement is facing by ion attacks. Furthermore, because the transition area in concrete is one the weak parts of concrete. It is tried to improve the durability properties of transition area that is mainly filled by cement and water. So, this research focuses on assessing the electrical resistivity of cement paste when it is integrated with pozzolan material in nano and micro scale. In to end, the cement paste without any additive is compared with cement paste integrated with nano-silica and micro silica. The amounts of additive materials are limited to 2.5%, 5%, 7.5% and 10% of cement weight. The two types of nano-silica have been used in this research that are liquid suspended nano-silica and solid nano-silica particle. So, the 3 different pozzolan materials were used that include two different nano silica (liquid and solid) and micros silica. Then all the results have been compared with results of ordinary cement paste as reference point. Then the samples were tested at age of 3, 28 and 90 days. The results show that before age of 3 days, adding nano silica or micro silica led to decline the electrical resistivity because the pozzolanic reaction is not started, but at age of 28 days the top achieved electrical resistivity belong to the samples which has nano-silica in its mixture. However, after age of 28 days, just the samples with micro-silica have electrical resistivity growth. The results of the samples that contain the both of nano-silica and micro-silica are between the results of samples that contain micro-silica and the samples which integrated by nano-silica. Keywords: