Russian Journal of Applied Chemistry最新文献

Heat exchanger unit is one of the most important parts in refineries, to ensure the efficiency of heating and cooling process. The improvement of heat exchange not only gives a good refined product, but also decreases the total cost. In this work, we collected heat exchangers´ data and operating conditions and simulated them in HYSYS program to predict heat exchangers´ performance. The choice of the HYSYS program in the study is due to the accuracy of the simulation environment results, which sometimes reaches 98% between the simulation and the reality in the factory. These results were particularly shocking for low-efficiency heat exchangers and indicate multiple causes that affected the low performance of heat exchangers. The large variation in efficiency of these heat exchangers is due to the accumulation of some muds and sediments contained in crude oil and refinery products and the blockage of some flow patterns due to calcified salts over time, it was not known with this accuracy until after using the HYSYS program to simulate the realistic operating conditions along the path of the crude oil flow in this operating unit. Heat exchanger efficiency variation maps along the production process path gave a description of finding and solving difficulties. The current state of Najaf Refinery unit 2 heat exchangers after this study shows the actual low efficiencies of most exchangers gave the Najaf Refinery management and engineers the decision to make emergency maintenance, cleaning process and replace some of these heat exchangers. The optimum operating conditions and change in connection scheme of heat exchangers can be also determined by HYSYS as a forward step.

The biosynthetic process, also known as green synthesis, is particularly attractive due to its ability to reduce nanoparticle toxicity. Vitamins, amino acids, and plant extracts are currently gaining widespread popularity. Conversely, this technique creates nanoparticles by utilizing reducing agents derived from plants and bacteria. It has various advantages, including non-toxicity, environmental safety, cost-effectiveness, biocompatibility, and energy generation. Nanoparticle manufacturing can involve a diverse range of components. Using grape leaf extract as a raw material, we have created an affordable and environmentally safe way to produce titanium dioxide nanoparticles (GL-TiO₂ NPs) from a titanium isopropoxide solution. Nanoparticles were examined by using X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), Brunauer‒Emmett‒Teller (BET) analysis, with particle size analysis (PSA), Energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and Zeta potential analysis. The distinct peaks observed in the XRD pattern demonstrate the crystalline structure and level of quality of titanium dioxide (TiO₂) nanoparticles. The form and structure were examined by FE-SEM analysis, and EDS examinations. Data indicate that the size of the nanoparticle vary between 22 and 49 nm. The size distribution of the TiO₂ nanoparticles synthesized by a green method has been determined by utilizing a particle size analyzer (PSA) and XRD to measure the average crystalline size. The surface area of the created particles was determined using BET. The analysis revealed a specific surface area of 50.4716 m²/g. This paper underscored the advantages of utilizing nanoparticles in nanotechnology without any adverse impacts.

The engineering features of problematic soils could be frequently improved by chemical stabilization. Researchers have recently focused on industrial waste/by-product geopolymers as a cement substitute in the concrete making process such as alkali activated. This study explores the potential for enhancing the engineering characteristics of gypseous soil by utilizing calcium carbide residue (CCR), a byproduct of the acetylene production process combined with (LABSA) linear alkyl benzene sulfonic acid to form geopolymer. The geopolymer preparation was accomplished by merging a dilution of LABSA (300 acid/1000 mL distilled water) with a geopolymer (solid to liquid) blending proportion of 80 to 20%) by the whole dry mass of the soil. Mixtures of soil containing 2.5, 5, and 7.5% of the geopolymer mix content were made. The Single oedometer test (SOT) and the double oedometer test (DOT) were carried out in order to ascertain the lowest collapse potential value that correlated with the ideal geopolymer mixing ratio. The adequate geopolymer percentage was found to be 5% since it resulted a reduction in collapse potential by 88.7 and 94.4% for (SOT) and (DOT), respectively in comparison to the natural soil. For stabilizing gypseous soil in engineering projects, a combination of LABSA and CCR can be utilized as a workable, sustainable, and environmentally friendly substitute.

Gas turbines are widely used in electric power plants all over the world to generate energy. High temperatures affect the gas turbine’s efficiency. When the air temperature around the gas turbine ranges from approximately 40‒50°C, the efficiency and output power will decrease, due to the decrease in air density mass. The study of gas turbines was conducted at the Al-Quds Gas Station in Baghdad, Iraq, a city known for hot summers. A combination of Turbine Air Intake Cooling Systems (TIACS) is typically used to help cool the inlet air of a gas turbine. This study investigates of fogging cooling system (upstream), a new cooling technology to cool the air entering the turbine resulting in improved gas turbine performance and increased turbine efficiency. The two main parts of the indirect technology are the use of pipeline heat exchangers that deliver the water to the nozzle and nanoparticles Nano-Aluminum Oxide (Al₂O₃) to cool the water tank for heat exchange which cools the air entering the turbine. The results concluded the amount of efficiency produced increases when the water temperature in the pipe drops to 25°C and the air’s temperature upon entry the compressor is reduced by 12°C the water temperature for the sprinklers 25°C, the temperature value of the air entering the gas turbine decreased to 14°C by 1.68%.

Tungsten oxide (WO₃) is a wideband gap n-type, transition metal oxide semiconductor. It is a high refractive index trioxide compound that exhibits good corrosion resistance in solutions with strong acids. It also provides high-performance characteristics such as optical modulation, great durability, photochromic behaviors, and coloration efficiency. With such superior chemical and physical properties, tungsten oxide becomes suitable for a wide range of applications such as photocatalysis, sensors, and super-capacitance. According to previous studies, compositing other materials is a suitable method for electron-hole pair separation. This work reviews and illustrated the improved properties of WO₃ by combining with metals in the form of core-shell nanocomposites with metal cores and oxide shells have emerged as attractive materials with high stability and remarkable synergy between their components, which enable a combination of several attractive properties in the same material.

Nanodiamonds (NDs) exhibit various medical potentials making them promising material for biomedical applications. The aim of present work was to synthesize NDs using Hummers’ method. The synthesized NDs were investigated for their structure and morphology using Fourier Transform Infrared spectrum (FTIR), Ultraviolet-Visible spectroscopy (UV-Vis spectroscopy), and Scanning Electron Microscope (SEM). The antibacterial effect of NDs was measured using agar well diffusion method against varying clinical isolates of gram-negative bacteria (Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa) and gram-positive bacteria (Staphylococcus aureus). In that assay, the tested bacterial isolates were incubated for 24 h at 37°C with different concentrations of NDs (62.5, 125, 250 µg/mL). The test results indicated high sensitivity of the clinically isolated strain, S. aureus, to the NDs concentration of 250 µg/mL. In addition, The NDs preparation was used to treat S. aureus-infected wounds for continuous 15 days using two daily doses of 250 and 500 mg/kg in the mouse model. The wounds were measured for size, contraction, and healing time. The results indicated marked wound healing and reduced sizes of wounds in the treated animals compared to the control animal group. The study findings raise the possibility of use the prepared NDs formulation for the management of infected wounds.

In this study, different nano coatings were prepared using two main resins: Epoxy (Ep) and unsaturated Polyester (UPE). Nano titanium oxide (TiO₂), nano aluminium oxide (Al₂O₃) and nano clay were added in 1 and 4 wt % fractions by hand lay-up method. Surface roughness and anti-bacterial activity were tested on the coated specimens. The results showed that the addition of nanoparticles increased roughness for both epoxy and polyester at 4 wt % ratio, with the highest value noticed for polyester reinforced with 4 wt % of nanoclay (3.268 µm). The anti-bacterial activity of the surfaces on isolates of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) showed that the increase of nanoparticles for both epoxy and polyester led to enhancement in inhibition rate. Generally, the highest inhibition rates were 90% for E. coli bacteria for polyester coating with 4 wt % of TiO₂, also with 1 wt % additive the inhibition rates were 66%, while at epoxy with 4 and 1 wt % for the same type of bacteria the inhibition rates were 44 and 26% respectively. In S. aureus bacteria the inhibition rates bacteria for polyester were 56.80% with 4 wt % and 45.40% with 1 wt %, while there is no inhibition rates for epoxy for the same additive and bacteria type. In Al₂O₃ additives the inhibition rates for E. coli bacteria in polyester were 80 and 64% at 4 and 1 wt % additives respectively. Similarly at epoxy the inhibition rates were 32 and 42% at 4 and 1 wt % additives correspondingly. While the inhibition rates for S. aureus bacteria in polyester were 81.80 and 56.80%. But there are no inhibition rates for epoxy for the same additive and bacteria type. When adding nanoclay, there is no inhibition rates for epoxy and polyester with both E. coli and S. aureus bacteria.

This study investigates the selection of optimal dental composites through a Multi-Criteria Decision Making approach utilizing the Analytic Hierarchy Process (AHP) and Gray Relational Analysis (GRA) techniques. Six dental composite materials (A) SiO₂-ZrO₂, (B) BIS-GMA, UDMA and Bis-EMA blend, (C) Bis-GMA, UDMA, TEGDMA and Bis-EMA resins, (D) silorane and filler, (E) Bis-GMA, Bis-EMA and UDMA, and (F) SiO₂-Al₂O₃-K₂O were evaluated based on a set of Performance Defining Criteria (PDCs). The AHP method determines the following priority order for PDCs: shrinkage (PDC-2) > density (PDC-3) = compressive strength (PDC-6) > flexural strength (PDC-4) = flexural modulus (PDC-5) > fracture toughness (PDC-1). The GRA ranking of the dental composites is B > D > C > A > E > F. This research demonstrates the effectiveness of the hybrid AHP-GRA approach, particularly considering the successful application of the hybrid AHP-GRA for the first time, in achieving logical and robust results based on the inherent properties and performance of the investigated composites. Also, the shrinkage, density, and compressive strength characteristics had the greatest influence on choosing the best filling for tooth restoration. This research aims to support dentists in choosing the best dental filling from among the many fillings available with different and varied properties to provide the best-required performance for the filling.

In construction, the material was used to hold the gaps between bricks and blocks called cement mortar. Cement mortar is a mixture made from sand, binder (cement or lime), and water to homogenous. This mixture was supported with waste storage device like compact disc (CD) after converted to powder. Waste compact disc powder was added to the mixture at different weight percentage (2, 3, 4 wt %). The cement mortar reinforced was evaluated with compressive strength, hardness Shore D, and bending strength. Samples of cement mortar were fabricated according to Taguchi L9 orthogonal array. Statically, ANOVA (one-way analysis) was applied to all the data. The maximum result of compressive strength was showed at 4 wt % CD powder, 1.9 g cement, and 28 days curing in water. The optimum result of hardness was obtained at 4 wt % CD powder), 3.9 g, cement, and 28 days, curing in water. The optimum results of bending strength showed 2 wt % compact disc powder, 3.9 g cement, and 14 days curing in water. The results of the statistical program finds that the CD powder (wt %) and curing time in the water (days) have more influence on the properties of cement mortar reinforced compared to weight of cement (g). Finally, increased the weight percentage of CD powder improved the compressive strength and the hardness of the cement mortar.

The objective of this research was to examine the effects of YSZ/TiO₂ composite coatings applied to the surface of Ti–13Zr–13Nb titanium alloy in order to improve its biocompatibility and functionality in the context of medical applications. Experimental evaluations of corrosion as well as the tape testing was conducted in this research endeavor on joint implant alloys composed of Ti–13Zr–13Nb and coated with YSZ/TiO₂ nanoceramic. The parameters utilized in the electrophoretic deposition procedure were as follows: 60 V, 7 min, 15% concentration, and 400 degrees of grinding. The parameters of the dip coating conditions were as follows: 60°C temperature, 10 s of grinding time, 15% concentration, while 400 degrees. For analysis purposes, we employed high-resolution scanning electron microscopy (FE-SEM) images of the coated alloys. A comprehensive examination of the thickness and microstructure of the coated surfaces was performed by employing atomic force microscopy (AFM) and optical microscopy. The corrosion resistance of the titanium alloys with a top coating was evaluated using electrochemical techniques, namely cyclic polarization and polarizing (Tafel), in a body fluid simulator (SBF). In order to evaluate the adhesive strength of the coatings, a tape tester was employed. Using the subsequent values, the corrosion resistance of the coated Ti–13Zr–13Nb alloys was assessed: at 37°C, both coating alloys demonstrated enhanced resistance to corrosion in Ringer’s solution. In contrast, corrosion was observed to be slower in the Ti–13Zr–13Nb alloy coated via electrophoretic deposition than in the alloy coated via dip coating (8.282 × 10^–8 vs. 2.166 × 10^–7, respectively).