Water absorption characteristics of composite materials and gel coats are crucial for their applications in marine industry. The physical and mechanical properties of composite parts are influenced by moisture. Water absorption of five gel coat compositions based on epoxy vinylester resin and neopentylglycol unsaturated polyester resin and their blends was studied in this work. The influence of nanographene addition on the water absorption of these gel coats was also investigated. The results showed that epoxyvinylester resin had the lowest and neophentylglycol unsaturated polyester resin had the highest water absorption levels, and their blends, as expected, showed the same behavior. TEM, SEM and XRD were used to analyze and characterize the dispersion and distribution of nanographene particles in the polymer matrices. The results showed both dispersed and non-dispersed flakes in the polymer matrices. It was also shown that the addition of nanographene resulted in gel coats with lower water absorption levels. پرونده مقاله

In the academic and industrial sectors, there has been a significant level of attention directed towards novel surfactants, particularly nano gemini surfactants, owing to their distinctive characteristics in recent times. The utilization of the quasichemical approximation has enabled the determination of phase equilibrium and the mixing properties for solutions of this nature. The Helmholtz free energy, mixing entropy, and mixing energy were ascertained through the variation of hydrophilic and hydrophobic units in nano gemini surfactants. The augmentation of the hydrophilic properties of the nano gemini surfactant has been observed to enhance the reaction of mixing. In turn, there is a reduction in the energy required for mixing. Furthermore, the negative value of the Helmholtz free energy of mixing has been observed to increase. When the hydrophobicity of a nano gemini surfactant increases, a contrary result to previous findings is observed. The mixing entropy remains unaffected by the hydrophobic and hydrophilic units of the nano gemini surfactant. An increase in the hydrophobic tail length of the surfactant leads to a corresponding increase in the two-phase equilibrium region. Conversely, a decrease in the hydrophobic tail length results in a decrease in the two-phase equilibrium region. پرونده مقاله

An extensive review of the literature showed that both graphene and Cloisite 30B nanosheets are widelyemployed to modify the crystalline structure and piezoelectic properties of polyvinylidene fluoride (PVDF).Due to the similarity in the geometry of these nanoparticles a comparative study is reported to find the stemsof difference in their effects on crystalline structure of PVDF. Scanning electron microscopy (SEM) of thesecomposites showed that large and wide graphene particles are dispersed in PVDF matrix whereas theirthickness is well below 100 nanometers. Meanwhile, a careful inspection of SEM micrographs of Cloisite 30Bloaded composites revealed existence of smaller particles with almost the same particles thicknesses. Bothtechniques of Fourier transform infrared (FT-IR) spectroscopy and wide angle X-ray diffraction (WXRD)witnessed changes in the crystalline structure of PVDF. The overall finding was that Cloisite 30B improvesthe polar beta phase of PVDF crystals, whereas a revers effect was found in the presence of graphenenanosheets. These observations were accounted for by differences in surface geometry and surface free energy(surface tension and interfacial tension). Based on the data available for surface properties of these twonanosheets it was found that surface properties of Cloisite 30B is very close to those of PVDF, whereas thesurface properties of graphene are far from those of PVDF. Also a lower interfacial tension was found to beactive in PVDF-Cloisite 30B system compared to that operative in PVDF-graphene system. An intimateinterface along with proper surface texture led to higher content of PVDF’s beta crystals in case of Cloisite30B nanocomposite. پرونده مقاله

Tire recycling or tire recycling is a process in which car tires are no longer worn out or are no longer suitable for use because of a rupture or unrepairable failure. These tires are among the most significant waste that is very problematic. This problem is due to the persistence and persistence of tires and their high volume of production. It is estimated that 259 million tires are discarded each year. In this research, the Preparation stages of production of activated carbon nanofibers produced from the recycling of worn tire rubber with different percentages of different solvents of potassium hydroxide, ethanol, and toluene were studied and tested. To achieve a solution for worn tire tires, a certain amount of scraped rubber fragments was dissolved in potassium hydroxide, ethanol, and toluene solvents, and electrospinning solutions were determined and prepared and to produce nanofiber layers, Electrospinning operations are performed. By scanning electron microscopy images, the mean diameter of nanofibers obtained in potassium hydroxide solvent was the lowest, and scanning electron microscopy images confirmed the absence of willow in the produced nanofibers. The efficiency of carbon production was determined as 37.2%. To confirm the formation of activated carbon, FTIR spectra were used, which confirmed the presence of spike related to the aromatic ring formation of activated carbon nanofibers after activation. پرونده مقاله

A promising and reusable nanohybrid based on carbon quantum dots (CQD) was fabricated as a sorbent for ultrasound- and magnetic-assisted dispersive micro-solid-phase extraction(US-M-A-DMSPE) followed by high-performance liquid chromatography with ultraviolet detection (HPLC-UV) for simultaneous trace determination of cephalosporins (Cefdinir & Cefixime) in human plasma. The structure of the prepared sorbent was characterized by x-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Under the optimized conditions, the nanosorbent provided high adsorption and selectivity toward the analytes. The limits of detection and the coefficients of determination (r2) with dynamic ranges for cefdinir & cefixime were estimated. The method was used for quantifying cefdinir & cefixime in plasma samples to evaluate the pharmacokinetic aspects,including the half-life (T1/2), the time to reach the maximum concentration (Tmax), the maximum plasma concentration (Cmax), area under the curve (AUC0-24) and area under the curve at infinite time (AUC0-∞). Reliable reproducibility as the intra- assay and inter-assay together with reasonable accuracy were obtained. پرونده مقاله

In this study, we aimed to enhance the electrical conductivity of polymeric layers for potential applications in organic electronics such as sensors and capacitors. Electrically conductive polythiophene (PTh) and polypyrrole (PPy) layers were deposited on a poly methyl methacrylate (PMMA) substrate using an in-situ chemical oxidative deposition method with FeCl3 as a catalyst and acetonitrile and deionized water as solvents. To further improve conductivity, multi-layer PTh and PPy, in the presence of carbon nanotubes (CNT), were applied on the PMMA substrate. The reaction times for synthesizing PTh and PPy were optimized to be 12 and 20 minutes, respectively, based on electrical properties. Fourier-transform infrared spectroscopy (FTIR) was used to identify the different components of the conductive polymers on the PMMA substrate. The morphology and thickness of the layers were investigated using scanning electron microscopy (SEM). The electrical conductivity of the layers was measured using a four-point probe device. The highest electrical conductivity of 100.93 S/cm was achieved for the two-layer poly pyrrole-polythiophene/CNT coating on the PMMA substrate. These findings demonstrate the potential of this multi-layer conductive coating for various organic electronic applications. پرونده مقاله

Water absorption characteristics of composite materials and gel coats are crucial for their applications in marine industry. The physical and mechanical properties of composite parts are influenced by moisture. Water absorption of five gel coat compositions based on epoxy vinylester resin and neopentylglycol unsaturated polyester resin and their blends was studied in this work. The influence of nanographene addition on the water absorption of these gel coats was also investigated. The results showed that epoxyvinylester resin had the lowest and neophentylglycol unsaturated polyester resin had the highest water absorption levels, and their blends, as expected, showed the same behavior. TEM, SEM and XRD were used to analyze and characterize the dispersion and distribution of nanographene particles in the polymer matrices. The results showed both dispersed and non-dispersed flakes in the polymer matrices. It was also shown that the addition of nanographene resulted in gel coats with lower water absorption levels. پرونده مقاله

Tire recycling or tire recycling is a process in which car tires are no longer worn out or are no longer suitable for use because of a rupture or unrepairable failure. These tires are among the most significant waste that is very problematic. This problem is due to the persistence and persistence of tires and their high volume of production. It is estimated that 259 million tires are discarded each year. In this research, the Preparation stages of production of activated carbon nanofibers produced from the recycling of worn tire rubber with different percentages of different solvents of potassium hydroxide, ethanol, and toluene were studied and tested. To achieve a solution for worn tire tires, a certain amount of scraped rubber fragments was dissolved in potassium hydroxide, ethanol, and toluene solvents, and electrospinning solutions were determined and prepared and to produce nanofiber layers, Electrospinning operations are performed. By scanning electron microscopy images, the mean diameter of nanofibers obtained in potassium hydroxide solvent was the lowest, and scanning electron microscopy images confirmed the absence of willow in the produced nanofibers. The efficiency of carbon production was determined as 37.2%. To confirm the formation of activated carbon, FTIR spectra were used, which confirmed the presence of spike related to the aromatic ring formation of activated carbon nanofibers after activation. پرونده مقاله

Bacterial cellulose (BC) is a significant biopolymer in medical applications and some research has been conducted to modify its rehydration ability. In this research bacterial cellulose was cross-linked with succinic acid (SA)/ Sodium hypophosphate (SHP) in different concentrations and then the wettability of treated and untreated BC was investigated. SEM and BET proved a new structural construction and higher porosity in the cross-linked BC. Additionally, ATR-FTIR showed the presence of ester bonds (COO) in the treated samples. Moreover, the thickness and water absorption were enhanced by 137% and 133% respectively and the cross-linked samples showed a higher water swelling rate. Therefore, cross-linked BC with succinic acid has a high potential for increasing BC shelf lifetime for biomedical applications. پرونده مقاله

Bacterial cellulose is produced by strains of Acetobacter and Acetobacter xylinum is the most important species producing it. Due to its nanostructure and morphological similarity to collagen, bacterial cellulose can be used for cell absorption and support. Consequently, this research presented a general description of bacterial cellulose, its applications in medicine, and utilization of hydroxyapatite/cross-linked bacterial cellulose composite scaffolds for bone tissue. Citric acid (20%) was used for cross-link, samples of bacterial cellulose were prepared and oven-dried, and hydroxyapatite (HAP) particles were then added at three concentrations (1, 2 and 4%). Using ATR-FTIR, XRD, FE-SEM, EDS and BET, the structure of the composites were compared. The results of ATR-FTIR confirmed that the HAP crystals contained a special carbonate that was similar to the apatite present in natural bone. XRD also indicated the characteristic peaks of HAP, and calculation of the size of the crystals using Scherrer equation demonstrated that the largest crystal size (81.42 nm) was that of the sample containing 20% citric acid with 4% HAP. Comparison of the FE-SEM images showed that the distribution and formation of apatite on the surface and cross-section were the best in the sample cross-linked with 20% citric acid and 4% apatite. The results of EDS analysis also indicated that all the precipitates contained calcium and phosphorus confirming the presence od HAP crystals, and the nanoparticles were also distributed uniformly in the scaffold structure. BET also showed that the sample cross-linked with 20% citric acid and 4% HAP had the lowest specific surface area and the highest porosity confirming the high uniformity of the 4% HAP distribution. پرونده مقاله

In the academic and industrial sectors, there has been a significant level of attention directed towards novel surfactants, particularly nano gemini surfactants, owing to their distinctive characteristics in recent times. The utilization of the quasichemical approximation has enabled the determination of phase equilibrium and the mixing properties for solutions of this nature. The Helmholtz free energy, mixing entropy, and mixing energy were ascertained through the variation of hydrophilic and hydrophobic units in nano gemini surfactants. The augmentation of the hydrophilic properties of the nano gemini surfactant has been observed to enhance the reaction of mixing. In turn, there is a reduction in the energy required for mixing. Furthermore, the negative value of the Helmholtz free energy of mixing has been observed to increase. When the hydrophobicity of a nano gemini surfactant increases, a contrary result to previous findings is observed. The mixing entropy remains unaffected by the hydrophobic and hydrophilic units of the nano gemini surfactant. An increase in the hydrophobic tail length of the surfactant leads to a corresponding increase in the two-phase equilibrium region. Conversely, a decrease in the hydrophobic tail length results in a decrease in the two-phase equilibrium region. پرونده مقاله

Staphylococcus aureus and Pseudomonas aeruginosa are pathogenic, opportunistic bacteria that are often transmitted to skin lesions and wounds through contaminated sheets, utensils, and staff in hospitals. Therefore, using fabrics with antimicrobial properties in such environments decreases the chances of contamination.In this study, a polyester/viscose fabric was immersed in fluorocarbon (FC) and gentamicin (GC) to investigate their antibacterial effect against Staphylococcus aureus and Pseudomonas aeruginosa. Additionally, the waterproof and blood-resistance characteristics of the samples were evaluated. Concentrations of 1.25, 2.,5, and 5 g/l of gentamicin and 60, 80, and 100 g/l of fluorocarbons were used for the polyester/viscose fabric immersion using the spray method. After treating the fabrics with gentamicin and fluorocarbon, they were heated at 180°C for 3 minutes for further stabilization.The agar disk diffusion method was used to investigate the inhibitory effect of fluorocarbons and gentamicin on the growth of the aforementioned bacteria and the results were recorded after 24 hours. The durability of the antibacterial effect was investigated by transferring the discs to a regrowth culture once more and keeping them there for 24, 48, and 72 hours. 1.25 g/l of gentamicin and 60 g/l of fluorocarbons had the least inhibitory effect against the bacteria. The best durability of the antibacterial effect resulted after 2 consecutive treatments. Moreover, 60 g/l of fluorocarbon exhibited the best waterproof and blood-resistance effects. پرونده مقاله

In this study, we aimed to enhance the electrical conductivity of polymeric layers for potential applications in organic electronics such as sensors and capacitors. Electrically conductive polythiophene (PTh) and polypyrrole (PPy) layers were deposited on a poly methyl methacrylate (PMMA) substrate using an in-situ chemical oxidative deposition method with FeCl3 as a catalyst and acetonitrile and deionized water as solvents. To further improve conductivity, multi-layer PTh and PPy, in the presence of carbon nanotubes (CNT), were applied on the PMMA substrate. The reaction times for synthesizing PTh and PPy were optimized to be 12 and 20 minutes, respectively, based on electrical properties. Fourier-transform infrared spectroscopy (FTIR) was used to identify the different components of the conductive polymers on the PMMA substrate. The morphology and thickness of the layers were investigated using scanning electron microscopy (SEM). The electrical conductivity of the layers was measured using a four-point probe device. The highest electrical conductivity of 100.93 S/cm was achieved for the two-layer poly pyrrole-polythiophene/CNT coating on the PMMA substrate. These findings demonstrate the potential of this multi-layer conductive coating for various organic electronic applications. پرونده مقاله

An extensive review of the literature showed that both graphene and Cloisite 30B nanosheets are widelyemployed to modify the crystalline structure and piezoelectic properties of polyvinylidene fluoride (PVDF).Due to the similarity in the geometry of these nanoparticles a comparative study is reported to find the stemsof difference in their effects on crystalline structure of PVDF. Scanning electron microscopy (SEM) of thesecomposites showed that large and wide graphene particles are dispersed in PVDF matrix whereas theirthickness is well below 100 nanometers. Meanwhile, a careful inspection of SEM micrographs of Cloisite 30Bloaded composites revealed existence of smaller particles with almost the same particles thicknesses. Bothtechniques of Fourier transform infrared (FT-IR) spectroscopy and wide angle X-ray diffraction (WXRD)witnessed changes in the crystalline structure of PVDF. The overall finding was that Cloisite 30B improvesthe polar beta phase of PVDF crystals, whereas a revers effect was found in the presence of graphenenanosheets. These observations were accounted for by differences in surface geometry and surface free energy(surface tension and interfacial tension). Based on the data available for surface properties of these twonanosheets it was found that surface properties of Cloisite 30B is very close to those of PVDF, whereas thesurface properties of graphene are far from those of PVDF. Also a lower interfacial tension was found to beactive in PVDF-Cloisite 30B system compared to that operative in PVDF-graphene system. An intimateinterface along with proper surface texture led to higher content of PVDF’s beta crystals in case of Cloisite30B nanocomposite. پرونده مقاله

A promising and reusable nanohybrid based on carbon quantum dots (CQD) was fabricated as a sorbent for ultrasound- and magnetic-assisted dispersive micro-solid-phase extraction(US-M-A-DMSPE) followed by high-performance liquid chromatography with ultraviolet detection (HPLC-UV) for simultaneous trace determination of cephalosporins (Cefdinir & Cefixime) in human plasma. The structure of the prepared sorbent was characterized by x-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Under the optimized conditions, the nanosorbent provided high adsorption and selectivity toward the analytes. The limits of detection and the coefficients of determination (r2) with dynamic ranges for cefdinir & cefixime were estimated. The method was used for quantifying cefdinir & cefixime in plasma samples to evaluate the pharmacokinetic aspects,including the half-life (T1/2), the time to reach the maximum concentration (Tmax), the maximum plasma concentration (Cmax), area under the curve (AUC0-24) and area under the curve at infinite time (AUC0-∞). Reliable reproducibility as the intra- assay and inter-assay together with reasonable accuracy were obtained. پرونده مقاله

In this research, the composite nanofibers of polyvinylidene fluoride/polydistylene/graphene oxide (PVDF/PDA/GO) have been produced and their thermal and choromic properties have been investigated.For this purpose, samples of PVDF/PDA/GO were produced. The results of examining the morphology of the produced nanofibers shows that the diameter of nanofibers is significantly decreased and the uniformity of the nanofibers increased by adding GO to the nanofibers. The decrease in nanofiber diameter causes increase in specific surface area of them. The increase of nanofibers specific surface area helps to improve the sensitivity of them. This was confirmed by reflective spectrophotometric test and their high color response to methanol solvent. Also, by heating the sample, it was observed that the produced samples are sensitive to 60 ° C and therefore, they are thermochromic. Because of choromic-thermal properties of PVDF/PDA/GO composite nanofibers, they can be used as a type of chromic sensors and/or thermal sensors. In PVDF/PDA/GO composite nanofibers, graphene oxide enhances the chromic sensitivity responses of polyvinylidene fluoride/polydiacetylene nanofibers. پرونده مقاله

Both graphene and Cloisite 30B nanosheets are widely employed to modify the crystalline structure and piezoelectic properties of polyvinylidene fluoride (PVDF). Due to the similarity in the geometry of these nanoparticles a comparative study is reported to find the stems of difference in their effects on crystalline structure of PVDF. Scanning electron microscopy (SEM) of these composites showed that large and wide graphene particles are dispersed in PVDF matrix whereas their thickness is well below 100 nanometers. Meanwhile, a careful inspection of SEM micrographs of Cloisite 30B loaded composites revealed existence of smaller particles with almost the same particles thicknesses. Both techniques of Fourier transform infrared (FT-IR) spectroscopy and wide angle X-ray diffraction (WXRD) witnessed changes in the crystalline structure of PVDF. The overall finding was that Cloisite 30B improves the polar beta phase of PVDF crystals, whereas a revers effect was found in the presence of graphene nanosheets. These observations were accounted for by differences in surface geometry and surface free energy (surface and interfacial tensions). Based on the data available for surface properties of these two nanosheets it was found that surface properties of Cloisite 30B is very close to those of PVDF, whereas the surface properties of graphene are far from those of PVDF. Also a lower interfacial tension was found to be active in PVDF-Cloisite 30B system compared to that operative in PVDF-graphene system. An intimate interface along with proper surface texture led to higher content of PVDF’s beta crystals in case of Cloisite 30B nanocomposite. articledetails پرونده مقاله

In the academic and industrial sectors, there has been a significant level of attention directed towards novel surfactants, particularly nano gemini surfactants, owing to their distinctive characteristics in recent times. The utilization of the quasichemical approximation has enabled the determination of phase equilibrium and the mixing properties for solutions of this nature. The Helmholtz free energy, mixing entropy, and mixing energy were ascertained through the variation of hydrophilic and hydrophobic units in nano gemini surfactants. The augmentation of the hydrophilic properties of the nano gemini surfactant has been observed to enhance the reaction of mixing. In turn, there is a reduction in the energy required for mixing. Furthermore, the negative value of the Helmholtz free energy of mixing has been observed to increase. When the hydrophobicity of a nano gemini surfactant increases, a contrary result to previous findings is observed. The mixing entropy remains unaffected by the hydrophobic and hydrophilic units of the nano gemini surfactant. An increase in the hydrophobic tail length of the surfactant leads to a corresponding increase in the two-phase equilibrium region. Conversely, a decrease in the hydrophobic tail length results in a decrease in the two-phase equilibrium region. articledetails پرونده مقاله