Nano-Structures & Nano-Objects最新文献

Polymer nanocomposites (PNCs) have showed the significant applications in the fields of packing, energy, safety, defense, sensors, EMI shielding, optoelectronics etc. Tungsten trioxide nanoparticles (NPs) were prepared by propellant chemistry technique using Azadirachta indica extracts as a fuel/surfactant. Conducting polyaniline (PANI) was prepared using aniline monomer and suitable polymerizing agents. Ex-situ nanocomposites were prepared by mixing the different weight percentage of NPs into PANI matrix. For the better dispersion of NPs in to the matrix, solvents like Dodesyl benzene sulphonic acid (DBSA) and Camphor sulphonic acid (CSA) were used. Crystal structure, morphological features and their dielectric response at room temperature were reported. Electromagnetic Shielding (EMI) studies were compared between the PANI-WO₃ composites prepared by CSA and DBSA solvents. Composites showed worthy shielding response of 80 dB with CSA and 38 dB with DBSA. Here, the protonation of the solvent and the dispersion of NPs with the polymer matrix matters for the shielding efficiency. Hence, prepared materials are suitable for packing of electronic devices which provides the better EMI shielding and also suppress the heat through effective absorption of EM waves of X-Band.

Cellulose nano fibril (CNF) can be selected as an agent of pickering emulsion in biofoam manufacture. This study thoroughly investigates the pickering emulsion method for producing biofoam, the characterization of CNF from pineapple leaves, the production of biofoam with various concentration of CNF and surfactant, and the effect of these parameters on the properties of wet foam and dry foam. CNF was created by mechanical grinding then the stability and morphology were evaluated. The pickering emulsion mechanism in biofoam manufacture was investigated using foamability and foam stability with various CNF and surfactant concentration. As the results, CNF concentrations will create varying zeta potential values. The morphology of CNF shows that it has a structure-like entangled network. The stability test demonstrates that adding CNF improves the stability and foamability of biofoam by the pickering effect. Biofoam without CNF has an unstable structure and is easily collapse when dried in an oven. The concentration of CNF and the amount of surfactant utilized altered the qualities of both wet and dry foam. The lower concentration of CNF and the addition of surfactant could increases foamability, high porosity, water absorption, and biodegradability; as well as low density, contact angle and bending characteristics. In biofoam that consists of 2 % CNF, the stability of wet foam increases as the amount of surfactant added, resulting in a biofoam with low tensile strength.

Nanotechnology, particularly the use of nanoparticles, has garnered significant interest due to their unique properties and diverse applications, notably in antimicrobial research. This study focuses on the synthesis of titanium dioxide (TiO₂) nanoparticles mediated by Spirulina using green synthesis methods and explores their antibacterial effectiveness against multidrug-resistant bacteria, including Methicillin Resistance Staphylococcus aeruginosa, Pseudomonas aeruginosa, E. coli, and Enterococcus faecalis. The synthesis process involved the reduction of a titanium precursor using Spirulina biomass extract. Various characterization techniques, such as UV analysis, SEM imaging, FTIR spectroscopy, EDX analysis, and XRD, were employed to assess the physicochemical properties of the synthesized TiO₂ nanoparticles. Results showed a prominent absorbance peak at 322 nm and a band gap energy of 3.850 eV. SEM imaging revealed spherical morphology with aggregation, while XRD analysis indicated 61.4 % crystallinity with anatase phase. FTIR spectroscopy identified functional groups present in the nanoparticles, and EDX analysis confirmed the presence of titanium and oxygen elements. The antibacterial efficacy of Spirulina-mediated TiO₂ nanoparticles was evaluated using the Agar well diffusion method against multidrug-resistant bacteria. The nanoparticles exhibited significant inhibitory zones of 22 ±3, 17±4, 11±2, and 15±3 nm at 80 μg/ml against MRSA, P. aeruginosa, E. coli, and E. faecalis, respectively. Minimal microbial inhibition was observed at concentrations of 3.906, 15.625, 15.625, and 31.25 μg/ml for MRSA, Pseudomonas aeruginosa, Enterococcus faecalis, and E. coli, respectively. The minimum bactericidal concentrations (MBC) were found to be 7.812, 31.25, 31.25, and 62.5 μg/ml for the respective bacteria. This study highlights the effectiveness of Spirulina-mediated TiO₂ nanoparticles against multidrug-resistant bacterial strains in a bactericidal mode of action. Further research is warranted to investigate the molecular interactions between TiO₂ nanoparticles and multidrug-resistant bacteria.

Spintronic device architectures consisting of ferromagnetic chromium oxide electrodes in single-walled carbon nanotubes field effect transistor (SWCNT-FET) configuration have been fabricated to act as strategic building blocks for next generation super-compact high-speed nanoelectronic devices for logic and memory operations. Stable thin films of chromium oxides consisting of half-metallic ferromagnetic chromium-di-oxide (CrO₂) were pulsed laser deposited (PLD) over lattice-matched rutile-type-tetragonal intermediate TiO₂ thin layers over thermally oxidized Si substrates for engineering of the spintronic device structure. Focused ion beam (FIB) milling was applied to the ferromagnetic chromium oxide thin films for patterning of the source (S) and (D) electrodes. Typical electrical characteristics derived by lnρ vs. T^−1/2 plots confirmed spin-dependent transport (SDT) as the dominant mechanism of electrical conduction upto temperatures of ∼280 K along with negative magnetoresistance (MR) of ∼30 % at 278 K. Electrical characteristics (output and transfer) of the spintronic device structure were drawn under application of magnetic field (H) in out-of-plane geometry at the temperatures of 5.6 K, 250 K & 300 K. Drain current (I_d) is demonstrated to be controlled effectively as a function of gate bias (V_g) for different fixed V_d-biases at all the device operating temperatures. Change in %MR as a function of gate voltage (V_g) was acquired at T = 250 & T = 300 K that displayed higher %MR change under out-of-plane geometry of applied field of 0.75 T of the spintronic device operation.

Photocatalytic, antioxidant, and electrochemical properties of one-pot hydrothermal synthesized chlorine and calcium co-doped WO₃ nanowires (Cl-Ca@WO₃) were studied. The prepared WO₃-based nanowires were characterized using various analytical techniques. The UV–visible and Photoluminescence analysis showed that the band gap energy decreased from 2.49 eV for WO₃ to 1.80 eV for WO₃ nanowires that were co-doped with 4 % chlorine and 1 % calcium (4:1).Higher Scanning and Transmission Electron Microscopic analysis, showed that Cl-Ca@WO₃nanowires shapes changed and that they formed long and short bundles of nanowires based on the Cl-Ca mixing ratio. X-ray diffraction (XRD) analysis revealed a monoclinic phase even after the doping with Cl and Ca. The textural analysis showed an increase in surface area (4.216 m²g⁻¹ to 16.031 m²g⁻¹). The photoreaction method removed 31.94 % of the brilliant green dye by WO₃ nanowires and 88 percent using Cl-Ca@WO₃ at 240 min.The order of abundance of metals in the dyeing wastewater is Cu(1.76 ppm)> Cr (1.66 ppm)> Pb(1.26 ppm)> Ni (1.15 ppm) and the order of removal by each nanocatalyst at maximum time of 120 is as follows; WO₃: Cr> Ni> Cu> Pb, Cl-Ca@WO₃ (1:2): Cu > Cr > Ni > Pb, Cl-Ca@WO₃ (4:1): Cr > Cu > Ni > Pb.The pseudo-second-order model best described pollutant uptake and that Cl-Ca@WO3 was reusable after the fifth cycle. The antioxidant activity assayed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) revealed that Cl-Ca-WO₃ performed better with IC₅₀ value of 70.95 at 100 µg/mL. The electrochemical tests discovered that Cl-Ca-WO₃ nanowires have better kinetic performance and higher spontaneous energy than WO₃ nanowires.

The utilization of materials derived from starch has attained remarkable interest in the present-day world, owing to their environmentally friendly attributes, like, sustainability, biodegradability, and low carbon footprint. Despite these advantages, starch-based materials exhibit certain limitations, such as deficient mechanical strength, subpar temperature resistance, and inadequate physicochemical properties, which render them unsuitable for use in food packaging. Bionanocomposites, on the other hand, hold the potential to surmount these challenges and supplant the non-biodegradable, petroleum-based plastics that are currently utilized in food packaging. This review article emphasizes the mechanical and barrier properties of starch-based materials, as well as the processing methods that are pertinent to their application in food packaging. Moreover, it delves into the various forms of starches and nanofillers that have been studied for use in food packaging applications. The review concludes with suggestions for future research and a summary of the studies that are reviewed.

Biochemical synthesis of calcium phosphates (CaP) with use of enzymes is a novel trend in the synthesis of hydroxyapatite (HA) and other biocompatible calcium salts and composites. These compounds are biocompatible, possess good mechanical properties, and are suitable for a variety of purposes in bone tissue engineering. In this review, we discuss the biosynthesis (or enzymatic synthesis) of calcium phosphates and its comparison with conventional chemical methods. Main attention is paid to properties of CaP compounds for biochemical applications, classification and role of various enzymes in the biomineralization processes, role of bacteria and fungi, mechanisms of mineralization in several steps and possible real-time monitoring. A large number of morphologies of biochemically obtained CaP is shown, in particular for nanoscale range. Enzymes in natural biomineralization processes with participation of common bacteria, possessing a periplasmic alkaline phosphatase, are discussed in the point of view of their contribution in formation of fossils and rocks. CaP composites with natural biopolymers (chitosan, polysaccharides, cellulose) and synthetic polymers are described, as well as CaP compounds, functionalized with a series of biomolecules. The use of biowaste (animal, plant and aquatic origin, such as bone waste, eggshells, naturally derived biomolecules and biomembranes, marine organisms, etc.), used as raw materials for the preparation of CaP, is also shown.

Tricyclohexylphosphine sulfide (Cy)₃PS, a solid-structured phosphine sulfide precursor, was used for the first time in the synthesis of sphere-shaped colloidally stable β-HgS CQDs. DFT calculations applying the TPSS-D₃/def2-TZVP level of theory in the gas phase showed that the chemical reactivity of the titled precursor is similar to that of TOPS. The nanocrystals produced using HgCl₂/(Cy)₃PS/THF were colloidally stable, possessing near- and mid-infrared absorptions. As the reaction time increased, the first excitonic peaks were redshifted in the near-infrared window between 0.8 and 1.1 µm. Meanwhile, the red shifting of the mid-wavelength intraband (1S_e‐1P_e) absorption peaks was between 3.9 and 4.8 µm. A good agreement between the diameters calculated using the atomistic tight-binding approach and those obtained using TEM was observed. The concentration and molar absorption coefficient (ε₄₀₀) of the prepared QDs were determined as well. An increase in the ε₄₀₀ of the quantum dots with increasing reaction time was shown. XPS elemental analysis showed that HgS NCs with a nearly equal atomic ratio of Hg:S were poorly colloidally stable, and their FT-IR spectra had no intraband absorptions in the mid-IR window. Meanwhile, high colloidally stable and mid-wavelength intraband absorption peaks in the FT-IR spectra were shown for mercury-rich HgS CQDs.

Using magnetic and biodegradable polymers for removal of soluble pesticides can reduce environmental and human health damage caused by their presence in rivers, streams, and lakes. In this study, we develop and characterize the crystallinity and thermal properties of novel magnetic hydrogels based on polysaccharides, zeolites, and magnetite (Fe₃O₄) magnetic nanoparticles (MNs) functionalized with 3-aminopropyltriethoxysilane (Fe₃O₄@NH₂), supported in poly(methacrylic acid)-co-polyacrylamide networks. The potential of the hydrogel for herbicide removal, specifically paraquat, is also investigated. The Fourier-transform infrared spectroscopy, X-ray diffraction analysis, thermogravimetric, kinetic, and swelling degree analysis results demonstrate that MNs do not affect the physicochemical properties and pesticide sorption. However, minor changes, such as the peak at 2θ = 35.57º representing the (311) plane of Fe₃O₄, confirmed the incorporation of MNs into the polymer matrix. The increase in pH caused an increase in the swelling degree from 1.2 to 10.0 w.w⁻¹, indicating an increase both the pore size, and possibly, in the removal properties. The adsorption results of paraquat through ultraviolet–visible spectroscopy measurements show a small difference in absorptive capacity (q_eq) between pure hydrogel (12.95 mg.g⁻¹) and hydrogel with 2.0 % functionalized Fe₃O₄ NPs (12.99 mg.g⁻¹). Overall, incorporating Fe₃O₄ NPs in the hydrogel matrix yields materials with promising characteristics and while offering easier, safer removal from the environment.

Plant extract mediated biogenic synthesis of silver nanoparticles (AgNPs) has garnered considerable attention in nanotechnology due to its promising wound healing properties. This eco-friendly and cost-effective approach utilizes natural sources, such as the ethyl acetate extract of Nigella sativa L. (N. sativa) seeds, as a reducing agent. In this study, AgNPs were synthesized biogenically using N. sativa extract, and their wound healing potential was systematically assessed. Several methods for characterization are employed, incorporating ultraviolet-visible (UV-Vis) spectroscopy, fourier-transform infrared (FTIR) spectrometry, X-ray diffraction (XRD), scanning electron microscope (SEM) and dynamic light scattering (DLS) analysis were utilized to confirm successful synthesis and provide insight into the chemical and physical properties of AgNPs. When compared to a control group, human keratinocytes treated with AgNPs exhibited significantly enhanced proliferation and migration. Additionally, AgNPs were observed to increase the expression of wound-healing factors, (such as platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF)) as evidenced by western blot analysis. As a potent and naturally derived medicine for wound healing, AgNPs synthesized using N. sativa seed extract (ethyl acetate extract) potentially utilize the PDGF and VEGF signaling pathways to induce their therapeutic effects. Nevertheless, additional research is necessary to clarify the underlying mechanisms and assess the long-term safety and efficacy of this environmentally friendly method for producing AgNPs, which demonstrate remarkable wound-healing capabilities.