Results in Materials最新文献

(Ni–Mn) co-doped ZnO nanoparticles were synthesized for different doping concentrations (1 %, 2 %, and 3 %) and compared with the purely synthesized ZnO nanoparticles. Green synthesis route was followed to fabricate both pure and co-doped ZnO nanoparticles and the orange peel extract was used as the reducing agent. The main objectives of this research were to reduce the use of toxic chemicals and develop an eco-friendly green route for both pure and doped ZnO nanoparticle synthesis. Additionally, the co-doping effect on the photocatalytic activity was also observed. The synthesized particles were extensively characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) analysis, Fourier Transform Infrared spectroscopy (FTIR), and Ultraviolet–visible (UV–vis) spectroscopy. XRD analysis confirmed the exitance of ZnO nanoparticles with wurtzite structure. No extra peaks were found for the co-doped sample confirming the successful doping. The crystallite size decreased after doping and the range varied from 36 nm to 35 nm with increasing doping concentration. SEM analysis revealed the average particle size ranging from 66.42 nm to 37.52 nm with increasing doping concentration, the particle was irregular in shape, and agglomeration was observed. The FTIR data unveiled the existence of Ni–O, Mn–O, and Zn–O bands in the synthesized materials. The band gap of the NPs was determined from the UV–Visible spectroscopy analysis which varied from 3.30 eV to 2.71 eV with increasing doping concentration. The photocatalytic activity significantly improved with the increment of the doping concentration. The 2 % and 3 % doped samples degraded almost 97 % of the methylene blue dye at 30 min.

The present study investigated the effects of Hot Isostatic Pressing (HIP) on the fatigue performance of Laser Powder Bed Fusion (L-PBF) Ti–6Al–4V alloy under both 4-point bending and uniaxial testing. Three HIP-cycles were examined: standard, low temperature/high pressure (LTHP), and super beta. Moreover, an annealed heat treatment group was incorporated to compare against the HIP groups. The material microstructure was analyzed and compared across the heat treatments during the study, which showed the presence of α′ martensites, α+β Widmanstätten, and coarse equiaxed grains. Similarly, tensile and hardness testing were implemented to study the mechanical properties, where due to the effects of the HIP treatments, higher ductility but lower hardness values were recorded. Furthermore, fracture morphologies and stress-life (cycles-to-failure) (S–N) curves of the Ti–6Al–4V specimens concerning the fatigue behavior were analyzed. The HIP treatment groups behaved similarly during 4-point bending and uniaxial testing, with the LTHP obtaining a superior fatigue life behavior, followed by the standard and super beta HIP groups. In addition, the efficacy of HIP to reduce pores showed better results in the 4-point bending specimens, leading to few defects as fatigue initiators in contrast to the uniaxial specimens. Fractography results suggested that defects and microstructural features acting as fatigue crack initiators (FCI) govern the fracture behavior of uniaxial specimens. In contrast, only the presence of microstructural features controls the 4-point bending failure behavior.

Carbonate-substituted hydroxyapatite containing magnesium (Mg–C-HAp) was introduced through dissolution-precipitation treatment of hydroxyapatite containing magnesium (Mg-HAp) based on a black sea urchin (arbacia lixula) shells as novel biogenic materials. Based on chemical composition analysis, the Mg–C-HAp formed A- and B-type CHAp, which contained high carbonate ions. The Ca/P ratio of Mg–C-HAp was 1.707, very close to the biological bone apatite of 1.71. The Mg content in Mg–C-HAp was also relatively high, with the Mg/(Ca + Mg) ratio of 0.139, which is beneficial for antibacterial agents. The morphology of Mg–C-HAp showed particles with nanosize that provide a large surface area of ion promotion. The antibacterial test revealed that the Mg–C-HAp performed high antibacterial activity against Pseudomonas aeruginosa. The Mg–C-HAp-based porous scaffolds were then fabricated using the freeze-drying method with variations of polyvinyl alcohol (PVA) and gelatin fraction. According to the physicochemical analysis, the addition of PVA and gelatin in the scaffold structure decreased the crystallinity of the Mg–C-HAp/PVA/Gel scaffold. This lower crystallinity indicates high biodegradability, which is good for new bone growth. The macropores of the Mg–C-HAp/PVA/Gel scaffold were appropriate for new bone and blood vessel formation. The micropores of the Mg–C-HAp/PVA/Gel scaffold can be a medium for cells to grow. The microporosity of the Mg–C-HAp/PVA/Gel scaffold was also suitable for cell nutrient promotion. The compressive strength of the Mg–C-HAp/PVA/Gel scaffold was sufficient for bone regeneration. The Mg–C-HAp/PVA/Gel scaffold demonstrated high antibacterial activity against P. aeruginosa, so the Mg–C-HAp/PVA/Gel scaffold can maintain the role of Mg and carbonate content for antibacterial purposes. The good physicochemical, mechanical, and antibacterial properties of the Mg–C-HAp/PVA/Gel scaffold represented its suitable characteristics for antibacterial bone scaffolds.

Multifunction cavitation (MFC) has potential as an environmentally friendly surface-modification method. In the present study, the modified surface layer and the fatigue properties for MFC-processed low-alloy steel were investigated. When the processing time was longer than 2 min, the surface roughness increased and the surface potential decreased. The maximum compressive residual stress was induced after a processing time of 2 min, and decreased for longer processing times. Electron backscatter diffraction analysis of a cross section of a sample subjected to MFC for 30 min showed that the modified layer was thicker than that for samples processed for shorter times. The fatigue life at high cycle numbers increased for the specimens processed by MFC under the conditions corresponding to the greatest compressive residual stress. MFC processing was shown to be effective in improving the fatigue properties of steel, and therefore has potential as a next-generation surface-modification method.

Compared with poly (dl-lactide-co-glycolide) (PLGA) nanoparticles, triblock copolymer (PLGA-PEG-PLGA) nanoparticles composed of PLGA and polyethylene glycol (PEG) may improve the skin permeability of drugs. In this study, the usefulness of estradiol-loaded (E2-loaded) PLGA-PEG-PLGA nanoparticles in the treatment of osteoporosis was investigated by comparison with E2-loaded PLGA nanoparticles. The cumulative E2 permeation of each nanoparticle through rat skin was quantified using a Franz cell. The results showed that PLGA-PEG-PLGA nanoparticles had significantly higher permeation than PLGA nanoparticles. Next, in vivo treatment experiments were conducted using an ovariectomized rat model of osteoporosis. Nanoparticles were administered once per week in combination with iontophoresis. At 6 weeks after the initiation of treatment, significant improvement in bone density was observed in the treated group compared with the untreated group. The improvement in bone density tended to be greater in the PLGA-PEG-PLGA nanoparticle group versus the PLGA nanoparticle group. This may be attributed to the higher hydrophilicity of the particle surface of PLGA-PEG-PLGA nanoparticles compared with PLGA nanoparticles and the improved skin permeability of the particles through the trans-adnexal pathway.

The precast industry offers slab panels of different geometries according to the field conditions. These slab panels are popular in temporary constructions and beneficial in sustainability but have some financial limitations and local constraints. For a long time, the construction industry has used the arch action method, which restricts the stresses to the compression zone in concrete members and develops the required load-carrying capacity. For the same motives, industrial buildings have preferred semi-circular precast roofs, but the morphology was not suitable. For the proposed slab in this research, firstly, the typical industrial precast slab panel was doubled in width to minimize the time and efforts required for its casting, curing, and placement. Secondly, that doubled-in-width slab was provided with the arch action to confine the stresses to compression and benefit from the section entirely. Lastly, the top of the slab was kept flat to take advantage of the roof space. All these changes aimed for structural stability, reduced material's weight, improved load-carrying capacity, appropriate mobilization, and financial viability. A numerical approach and practical testing were adopted using the finite element modeling software, ABAQUS, to analyze load–deflection responses of both slabs through the concrete damage plasticity model. The proposed slab exhibited better performance as its capacity enhanced by about 1.5 times that of a typical slab. Although the volume of the material in the proposed slab increased slightly from 0.040 m³ to 0.045 m³, the reductions in joint filler materials, reinforcements, and efforts required for mixing and lifting machinery compensated for this increase significantly. Hence, the slab can be recommended for the industry to save the costs while taking heavier loads efficiently.

With the massive potential for nanofiber applications within the expanding field of functional materials and green energy materials, electrospinning has become an increasingly interesting method of fabrication, generating many different methods to fabricate different nanofiber types. However, due to limitations, either chemical or instrumental, some polymeric nanofibers can only be synthesised using co-axial or emulsion electrospinning methods. To date fabrication of poly (dimethylsiloxane) (PDMS)/poly (methyl methacrylate) (PMMA) nanofibers via electrospinning have been limited to coaxial method. These nanofibers have found use in medical fields as well as environmental remediation efforts as membranes and filters and also in new age wearable electronics. In addition, there have been no systematic studies documented on the parametric optimisation of PDMS/PMMA nanofibers using electrospinning, particularly concerning applied voltage, flow rate, and collector distance. In this work, a PDMS/PMMA co-polymer nanofiber, synthesised through an optimised emulsion electrospinning method, was fabricated and characterised. A systematic examination of electrospinning parameters was conducted and optimised parameters of 18.5 kV supplied voltage, 10 cm tip-collector distance and a flow rate of 0.2 mL/h resulted in the fabrication of nanofibers with an average diameter of ∼199 nm and super-hydrophobicity, with a contact angle of ∼162°, is reported on.

The need for progress in the development of energy supply devices such as batteries and large capacitors has led to the improvement and innovation of these devices so that they can store energy efficiently, and additionally, they must be small, light, with low production costs, and friendly to the environment. For these reasons, in this investigation results of the characterization of physical and chemical behaviors of graphene-manganese oxide and copper and manganese oxide-copper systems are studied. The graphene was synthesized through the electrochemical exfoliation technique and deposited as a film on common glass and silicon substrates via the spray technique, and over this film, Mn₂O₃ films were deposited through spin coating. The Raman results showed the presence of peaks D and G, located at 1534 and 1597 cm⁻¹, respectively. XPS analysis demonstrated that the graphene is made up of three layers. TEM studies determined that the graphene is polycrystalline, and XRD established the manganese oxide coatings’ growth along the (222) and (440) planes of Mn₂O₃. The optical behavior indicated that the absorbance of the graphene-Mn₂O₃ system decreases the energy gap in 0.8 eV concerning Mn₂O₃ films. The voltage-current measurements suggest that the density current in the discharge process of the Mn₂O₃–Cu electrode system was improved approximately 3-fold with the graphene-Mn₂O₃–Cu electrode system. The obtained results conclude that the addition of graphene to manganese oxide coatings increases their electrochemical performance, so graphene-manganese oxide could be used in energy storage devices.

Photo-galvanic cells are organo-inorganic chemical based devices. These cells use chemicals like photo-sensitizer(s), reductant(s), surfactant(s), alkali, solvent, and electrodes. Photo-decay and sacrifice of the chemical materials is imminent leading to the limited electrical output, efficiency and life of these cells. For realizing practical applications, the scalability of electrical output and stability of these devices is of utmost importance. Therefore, the long term photo-stability of Fast Green FCF dye-Fructose-Sodium lauryl sulphate (SLS)-NaOH electrolyte based cells has been studied in present work. The electrical output of the cell has been monitored over long period of time. Further, the photo-stability of electrolyte has been determined and analyzed spectroscopically. It has been observed that the Fast Green FCF dye-Fructose-SLS-NaOH photogalvanic cell device is capable of producing power even after decay of electrolyte. In early 24 h, about 90.54 % of dye degradation is observed. The cell is capable of giving current with even left out concentration ∼0.2 × 10⁻⁴ M (i.e., 9.46 % of initial concentration) of sensitizer. Further, the photo-degradation products (organic sulfonates) of FCF dye and SLS are also potential candidates for current generation. Cell charged in sunlight is capable of generating current even after cutting-off the illumination of electrolyte.

Al₂O₃–CaO-CNT(3,3) nanomaterial has demonstrated excellent electrical and mechanical properties in the absence of defects suitable for applications in microelectronics, batteries, and fuel cells. It is impossible to develop materials without the presence of defects. Therefore, this research work was instituted to investigate the electrical and mechanical properties of this nanomaterial in the presence of V_Al defect (a defect with lower formation energy in Al₂O₃) through DFT. The calculations were based on the Perdew, Burke, and Ernzerh (PBE) exchange-correlation functional, which uses the generalized-gradient approximation of an all-electron technique. The nanomaterial's spin-up and spin-down energy gaps (E_G) increased due to the defect, from 0.007 eV to 0.000 eV–0.560 eV and 0.129 eV respectively. However, these values are still lower than that of Al₂O₃, which is widely used as an insulator. The lowest and highest E_G recorded was at 0 $°C$ and 60 $°C$ for spin down, and at 0 $°C$ and 80 $°C$ for spin up respectively. The presence of the defect in the nanomaterial also led to the degradation of some of the mechanical properties majorly along (0-10), where the maximum bulk modulus decreases from 48.73 GPa to 8.40 GPa, the compressibility also increases from 56.82 GPa to 90.68 GPa.