Russian Journal of Applied Chemistry最新文献

In contrast to other configurations used in civil engineering, asphalt concrete (AC), which is a blend of bitumen and aggregates, is a sensitive substance. Consequently, efforts are made continuously by scientists and engineers to enhance the functionality of asphalt pavements. One strategy to enhance pavement performance is to modify the asphalt binder. Various materials have been used to strengthen asphalt concrete in modern times. Moreover, fibers are significant examples that are employed in this way. Nonetheless, it has been asserted that fibers have drawn the most attention among different asphalt modifiers due to their enhancing properties. Various studies have reported on the outcomes of adding a wide range of fibers to asphalt concrete. Therefore, the purpose of this study is to investigate how Hot Mix Asphalt (HMA) concrete behaves in the presence of certain carbon fibers (CF) in the asphalt mixture. This study examines the impact of incorporating carbon fibers into asphalt mixes through an experimental investigation. The current project uses asphalt with a grade of 40‒50 and aggregate percentages that meet Iraqi requirements. The creation of mixes with varying asphalt doses (4‒6.5%) yields the ideal asphalt content of the asphalt concrete mixtures. To produce specimens, the ideal bitumen concentration of 4.9% was employed. The ratio of carbon fibers to mixture volume (1.5%) is used to examine the effectiveness of paving mixes. The performance of HMA mixes was found to be enhanced by the inclusion of carbon fibers in terms of the HMA’s ability to withstand fatigue crack. CF acts as a reinforcement material, providing additional strength and stiffness to the asphalt binder-aggregate matrix, thereby delaying the onset of fatigue damage. CF reinforcement can lead to a significant increase in the fatigue life of asphalt mixtures. There was a 16% increase in stiffness, reducing the cracks under cyclic loading CF can delay the initiation of cracks in asphalt mixtures subjected to repeated bending loads. Fibers in the mixtures increasing amount of strain energy absorbed through fracture and fatigue activity, the number of cycles (Nf) greatly increased with additions 1.5% CF and improved by 46%.

Tissue engineering requires an optimal bone scaffold that has both a high porosity to facilitate cell attachment and an extended surface area to promote cell growth. Additionally, the scaffold should possess favourable bio-mechanical properties. The investigation of mechanical properties of scaffolds requires extensive experimental work to identify and understand their negative qualities. Thus, this paper presents a simulation approach to determine compressive strength, load-extension, deformation mechanism was detected. Soybean polymer or Glycine max (L) is the scientific name for the soybean plant, which is fabricated by 3D-printer machine in order to produce bio-scaffolds. Plant polymers have used in both experimental research and simulation systems. Both materials have the same four different designs and pore shape and size in simulation and fabrication process. A good numerical and experimental results were obtained, where four categories of scaffolds have achieved the required compressive strength for trabecula and biomedical purposes. Designs C0, C1, and C2 have made notable strides in this area.

The rapid utilization of non-renewable natural aggregates, bitumen, lime, and cement in construction for road pavement development and repair is unsustainable due to excessive solid waste production and inefficient disposal methods. To address this issue, researchers are exploring alternative materials derived from these wastes for road construction and maintenance. With the escalating costs of polymers and increasing plastic waste, a focus has shifted towards developing pavements using waste plastics. This study assesses the advantages of incorporating recycled (PET-Type 2) and virgin (PET-Type 1) polyethylene terephthalate polymers into 40/50 penetration grade bitumen using a common bitumen modification technique. In this study, the Marshall mix design method was used to create standard asphalt mixtures. The aim is to investigate how the addition of PET polymers impacts the performance of asphalt pavement. Furthermore, the objective is to determine the optimum proportions of two PET types and their influence on the performance of compacted asphalt paving materials for highways, utilizing Marshall properties and indirect tensile strength. Various concentrations of asphalt modifiers, ranging from 1 to 4 wt % of bitumen, were tested to gauge their effects on asphalt performance under high-temperature conditions. Laboratory experiments were conducted to analyze the physical properties of both unmodified and modified asphalt mixtures. Results indicate that incorporating 2% PET-Type 1 and 3% PET-Type 2, based on bitumen weight, into asphalt mixtures improved stability by 36.3%, and 29.5%, respectively. Additionally, the tensile strength and TSR value indicate sufficient resistance to moisture. The SEM analysis indicates that including modifiers led to a more uniform bitumen composition, resulting in improved cohesion and mechanical properties. Consequently, the characteristics of the asphalt mixture were enhanced. FTIR analysis demonstrates that test results can be used to predict the rheological properties of asphalt and examine the chemical bonds or functional groups found in pure and altered asphalt binders. The addition of PET-Type 1 led to the formation of a new absorbance peak corresponding to the C‒O bond, whereas the alteration with PET-Type 2 produced a peak corresponding to the C‒H bond.

In the present search, a study was made to evaluate and compare the performance of Poly(methyl methacrylate) PMMA resin properties, which used for prosthetic complete denture base material after the addition of two kind of fillers. Polypropylene (PP) and poly acrylonitrile (PAN) fibers were used as reinforcing materials. The influence of a selected weight ratio (1.5, 3.5, 5.5 and 7.5 wt %) were evaluated. The selected tests for this study were tensile strength, elongation at break percentage, modulus of elasticity, and finally some morphology examination. The obtained results clearly presents a decrease in tensile strength, modulus of elasticity, elongation at a various rate while the increase of used fibers ratio until the maximum value (7.5 wt %). The results at the maximum addition of tensile strength for both PMMA/PP and PMMA/PAN where 19 and 13 MPa respectively, compared to the neat polymer value (37 MPa). Elastic modulus evaluation for PMMA/PP and PMMA/PAN were 0.8845 and 0.8735 GPa respectively, so slight decrease from the neat PMMA (1.114 GPa). Also, elongation percentage for PMMA/PP and PMMA/PAN determined as 1.89 and 1.84 % respectively, compared to neat PMMA (4.66 %). The surface of PMMA/pure fracture was shown to be homogenous by Scanning electron microscopy (SEM) testing, however it is almost continuous for the PMMA/PP and PMMA/PAN. The fractured surface smoothness increased and showed a brittle to semi-ductile behaviour and a ductile transformation for the prepared composite. This study aims to develop some of the characteristics required for PMMA resin that are used in denture bases fabrication.

One of the most extensively distributed elements in the Earth’s crust is aluminum sulfate Al₂(SO₄)₃, used in vaccinations, medications, and food additives. Vitamin C, a necessary nutrient, cannot be generated by humans due to the absence of a crucial enzyme in the biosynthesis route. Previous studies do not report enough data on the role of aluminum sulfate Al₂(SO₄)₃ and vitamin C as companions, so the current study addressed this affair. The twenty rats were divided into 4 groups, five for each group: group 1―control, group 2―accompanied by Al₂(SO₄)₃ at 0.1 mg/1, group 3―accompanied by Al₂(SO₄)₃ at 0.2mg/L and group 4―Al₂(SO₄)₃ at 0.2 mg/L plus vitamin C. For 21 days, the appropriate doses were given orally to rats. Histological analysis of the heart tissue revealed that a lack of effect of aluminum sulfate on inflammatory cells especially macrophages, meaning that vitamin C had an antagonistic effect on aluminum sulfate in when treated doses of Al (0.2 mg/L) with vitamin C.

In this study, an emulsion liquid membrane (ELM) was used to extract direct red 80 (DR-80) dye from an aqueous solution as a technology to remove organic contaminants from industrial wastewater. The ELM was made up of tetra-n-butylammonium bromide as a carrier, Span 80 as an emulsifying agent, dichloromethane as a solvent, and ammonia as stripping phase. Critical operational parameters that could influence extraction efficiency were investigated and determined through the response surface methodology (RSM) approach. These parameters were carrier concentration, stripping phase concentration, ratio of stripping phase to membrane phase (S/M), and ratio of membrane phase to feed phase (Em/Ef). Then, through Design Expert and using the Box–Behnken method, twenty-nine experiments were carried out, and optimum values for maximizing extraction were obtained. Moreover, the stability of ELM leakage and swelling factors was evaluated. The optimal conditions for DR-80 dye extraction through the Box–Behnken method for ammonia concentration, carrier content, (S/M), and (Em/Ef) were 0.003 molar (M), 0.025 g/L, 1.4, and 0.6, respectively, and in this condition, the extraction of DR-80 was 100%. Therefore, it was concluded that the ELM process was a suitable method for removing and recovering DR-80 from wastewater.

In the work, polypropylene meshes were obtained by the method of additive technologies and their structure and properties were studied. The grids were printed on a Creality K1 MAX 3D printer with a 0.2 mm nozzle diameter and with OrcaSlicer software. It turned out that when printing small-thickness polypropylene meshes, certain difficulties arise (the printing process is more complicated, the level of adhesion to the printing table and interlayer adhesion is lower, resulting in various defects). As a result of optimizing the printing parameters, it was found that the printing speed in the range of 30–60 mm/s allows for high production speeds while maintaining excellent adhesion between the layers and minimizing the risk of deformation. Printing with a polymer layer height of 0.2 mm in one layer has become optimal. It is shown that the structural parameters of the obtained meshes differ from the specified ones, which must be taken into account when producing products using this method. It was determined that the average mesh thickness was 0.29 mm, the mesh size was 1.2–1.4 mm, and the thread thickness was 0.22–0.27 mm. The mechanical properties of the mesh material were judged by the tangential stiffness calculated for the case of medium bending according to the classification of H.M. Mushtari and determined on a special device of the experimental installation using a substrate of thin polypropylene film 0.04 mm thick to ensure tightness in the loading system of the test samples. The tangential stiffness of the resulting polypropylene mesh was 4.18–5.91 kg/cm. Fragments of the test from the beginning to the rupture of the grid are presented – types of the dome formed at various loading pressures. It has been found that polypropylene meshes printed on a 3D printer are characterized by spontaneous polarizability, that is, they are characterized by the presence of a polarization charge in the filaments that persists for a long time. The values of the electret properties of polypropylene meshes on the 20th day of storage (during charge stabilization) were as follows: surface potential 0.10 kV, effective surface charge density 0.056 µL/m², electric field strength. 6.7 kV/m. This allows them to be used, for example, as electret filters, which are known to have a high degree of purification.

The principal nitrogenous metabolite of proteins is the urea linkage, which is an important structural component in many bio-active compounds. The hydrogen bonding capacity and metabolic stability of the –NH–CO–NH– moiety have resulted in its insertion in potent urea and ureidopeptide conjugates and bioactive oligomers. Comparatively, these molecules are more inflexible due to strong hydrogen bonding properties and possess greater metabolic constancy, along with improved pharmacokinetic properties such as absorption, transport characteristics and low toxicity. It is our intention that the present work provides a succinct exploration of the synthesis of the ureas and ureidopeptides.

In this paper, an inorganic-organic hybrid PAMgA/SiO₂/K/GCC composite waterproof material was prepared by free radical polymerization using polymagnesium acrylate (PAMgA) as the substrate for the composite waterproof material. Silica (SiO₂), Kaolin (K), and Ground calcium carbonate (GCC) were used as inorganic modified fillers. The response surface methodology (RSM) Box-Behnken design (BBD) was utilized to optimize the effect of the addition of an inorganic modified filler on the tensile strength of composite waterproof materials. The optimal ratios of SiO₂, K, and GCC in the composite waterproof materials were obtained. When the additions of SiO₂ was 6.776 wt %, K was 14.594 wt %, and GCC was 10.494 wt %, the tensile strength of PAMgA/SiO₂/K/GCC composite waterproofing materials was experimentally measured to be as high as 1.679 MPa. The water retention rate (15 days) reached 82.8%, the swelling ratio (35 h) was 26%, and the coefficient of impermeability was as low as 1.169 × 10^–8 cm/s. This composite waterproofing material exhibits a hybridized inorganic-organic structure, characterized by high tensile strength, effective water retention, swelling resistance, and seepage resistance. Its applications include its use as a sprayed membrane waterproofing material in underground engineering, where it demonstrates considerable promise.

Artificial teeth were manufactured from zirconia-yttria nano systems, zirconia-yttria-soda lime glass, zirconia-yttria-pyrex, and zirconia-yttria-silica with different weight ratios. The specimens were formed by using a single-stage hydraulic press of 3 tons and then sintered at 1100°C for soda-lime glass, 1200°C for Pyrex, and 1400°C for silica. Structural properties X-ray diffraction (XRD) tests were performed, and tests of physical properties: apparent porosity, apparent density, water absorption, and surface roughness. Results of X-ray diffraction showed that the mean phase is the tetragonal phase for zirconia, while the monoclinic phase appeared in a small ratio due to the stabilizing process by yttria since works to stop phase transformations with the appearance of glass phase. The results of the study of physical properties showed an increase in density and a decrease in porosity, the zirconia-yttria-soda lime glass system is the best because the porosity is low and reaches close to zero 0.01.