Abstract Aim: The removal of heavy metals from drinking water is one of the highest impact challenges in the water and wastewater industry. For this purpose, the use of methods such as solid phase extraction followed by the use of selective adsorbents is considered as one of the most important issues in the water and wastewater industry.
Method: In this research, in order to remove the polluting and toxic heavy metal cadmium from water in the water treatment industry, Fe₃O₄ nanoparticles with a diameter of 10 nm have been synthesized. In order to make these nanoparticles resistant to corrosion and erosive factors of the environment, they are covered with a silica shell and afterwards with the aim of removing cadmium ions from aqueous solutions, the surface of Fe₃O₄@SiO₂ nanoparticles is modified with 1,4-dihydroxyanthraquinone molecules. The synthesized nanoparticles are characterized in order to evaluate the efficiency of these nanoparticles in separating cadmium ions soluble in water has.
Results: The synthesized and functionalized magnetic nanoparticles have an effective surface area of 378 m²/g with black color and spherical morphology. The effects of the parameters of the amount of nano adsorbent, pH of the solution, various concentrations of the solution and test time in the removal of divalent cadmium ions are investigated. According to the experimental data, the optimal values for the absorption process at pH 7 by using 18 mg of adsorbent in 50 ml of cadmium solution with an initial concentration of 0.35 mmol/L lead to the removal of cadmium ions with a maximum absorption of 92% at ambient temperature in a period of 35 minutes. Moreover, the recyclability and reusability of Fe₃O₄@SiO₂-DAQ in the adsorption-desorption process of cadmium ion is investigated using a magnetic magnet, and the results confirm that this synthetic nanocomposite is an effective adsorbent with excellent performance in order to remove divalent cadmium ion from aqueous solutions.

Abstract Research subject: Global warming is the most important worldwide problem. CO₂ is one of the greenhouse gasses and its emission to the atmosphere causes global warming to increase. Porous adsorbents are great candidates for CO₂ adsorption and graphene aerogels are porous nanostructures with very low density and hierarchical porosity which is suitable for CO₂ adsorption. The source of pristine graphite for graphene oxide synthesis as a precursor plays a vital role in graphene aerogel nanostructure.
Research approach: In the current study, graphene oxide by modified Hummers method was synthesized with three different graphite sources. Graphene aerogels were prepared with synthesized graphene oxides via hydrothermal and freeze-drying methods to investigate their effect on graphene aerogel nanostructure. Finally, the CO₂ adsorption of graphene aerogels was evaluated. The samples were characterized by FTIR, XRD, SEM, and BET analysis.
Main results: The results indicated that the source of graphite has a significant role in the process of oxidation of graphene oxide by the modified Hummers method. XRD results of graphene oxides showed successful oxidation of graphite. The normalizing FTIR peaks of graphene oxides showed different intensities of oxygenated functional group peaks. FE-SEM results of graphene aerogels showed that less oxidation of graphite powder caused agglomeration of graphite plates and thick walls were formed. The macropore size in the structure of obtained aerogels (GAB and GAE) was 2.28 and 3.84 µm respectively which affected the CO₂ adsorption. Larger pores led to easier mass transfer of CO₂ molecules and higher CO₂ adsorption was achieved. Moreover, the high meso and micro surface area (111 and 115 m²/g respectively) in GAE increased CO₂ adsorption up to 1.04 mmol/g compared to GAB (0.724 mmol/g).

Abstract 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.

Abstract Research subject: Aspergillus niger stands as a versatile filamentous fungus renowned for its industrial significance in producing various organic acids, notably citric acid and oxalic acid. Low sugar concentration as substrate leads to the production of oxalic acid, therefore, this article delves into the intricate metabolic machinery orchestrating the synthesis of these acids within A. niger, shedding light on the pivotal role of culture media composition and metabolic activity.
Research approach: Through a comprehensive review of A. niger metabolism, this study elucidates the pathways involved in the biosynthesis of citric acid and oxalic acid, unraveling the intricate interplay of enzymatic cascades and regulatory mechanisms governing their production. Furthermore, it explores the impact of small molecules on metabolic flux through regulatory media, offering insights into strategies for controlling metabolic flux in order to eliminate oxalic acid production and amplify the citric acid production considering low sugar content of 30 g/l.
Main results: After careful review of previous researches, key reactions and genes was found and introduced for future researches in order to control the A. niger products. Examination of small molecule as a regulator in culture media not only elucidated the importance of culture media composition but also employing them helped us to redirect flux from oxalate toward citrate. NH₄, Leucine, Cysteine, NaF, Glutathione, and Metformin were all found to be effective in the elimination of oxalic acid. In this regard, employing them leads to the production of 1868, 1530, 2093, 2250, 787, and 675 mg/L oxalic acid in comparison to the control culture media in which 5560 mg/L oxalic was produced. In addition, elimination of oxalic acid in some cases leads to the production of more acids like the culture containing NH₄, Cysteine and Metformin.

Abstract One of the problems related to oil recovery is water production, which reduces the production life of oil reservoirs and wells. Nowadays, the polymer gel injection method is used to control water production in the reservoir. In this study, an attempt has been made to investigate the rheological properties of xanthan-based hydrogels, considering Iran's reservoirs and also due to the existence of environmental problems in the field of synthetic polymers. The strength and stability of hydrogels can be applied by changing environmental conditions as a function of time and shear rate. For this purpose, the viscoelastic properties of hydrogels, including the elastic and viscous modulus, have been studied in relation to temperature, time and deformation rate for the gelant solution. Also, the effect of the composition of hydrogels, including the polymer concentration, the weight ratio of the crosslinking agent to the polymer, and the weight percentage of silica nanoparticles was considered in the study of rheological properties. Additionally, gelation time has been studied as one of the most important determining parameters of hydrogel during injection in porous medium.

Abstract Research Subject: Optical sensors based on porous coordination polymers or metal-organic frameworks (MOF) with luminescent properties with high sensitivity and selectivity are considered as important identification tools in chemical and environmental research. Today, pesticides/herbicides are widely used in order to protect the widely used food resources of human society against pests and to preserve the richness of arable land against weeds and unnecessary things in industries. Agriculture is considered. A large or chronic amount of these compounds can cause high levels of toxicity in humans, animals and plants and endanger the lives of organisms. Therefore, the identification of this group of compounds is of great importance.
Research Approach: In this study, metal-organic framework UiO-66-NH₂ fluorescence nanosensor (1) was synthesized to identify the herbicide Trifluralin (TFA) by ultrasonic method. The properties of nanosensor 1 were identified by X-ray powder diffraction analysis, infrared Fourier transform, thermal analysis, photoluminescence spectra, ultraviolet-visible spectrophotometry, and scanning electron microscopy. The blue emission of compound 1 caused by n-π* electron transfers of 2-aminoterephthalic acid ligand was investigated to identify TFA. The experimental results show that the blue fluorescence emission of nanosensor 1 is turned off in the presence of TFA molecule and the gradual increase in its concentration.
Main Results: Nanosensor 1 is associated with fast, stable, selectable response and high sensitivity in determining TFA. Considering the good linear correlation of the fluorescence response of nanosensor 1 to TFA concentration in the range of 10 to 100 µM and the lowest detection limit (LOD) equal to 2.32 µM, it indicates the reliability and practicality of the synthetic nanosensor in identifying TFA herbicide.