Journal of nanoscience and nanotechnology最新文献

Pristine TiO₂ and x% Ru/TiO₂ catalysts with different wt.% of Ru (x%= 1.5%, 2%, 2.5% and 3%) were synthesized using sol-gel and simple impregnation methods. Different characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), High-resolution transmission electron microscope (HR-TEM), Inductively coupled plasma-optical emission spectrometry (ICP-OES) and Thermogravimetry/Differential thermal analysis (TG/DTA) were used to study the physicochemical and morphological properties. The XRD patterns of the as-prepared pristine TiO₂ catalyst showed high crystalline nature. The HR-TEM images revealed that the Ru nanoparticles (NPs) were evenly dispersed on the TiO₂ surface. The prepared catalysts were evaluated for their catalytic activity towards the liquid phase hydrogenation of ethyl levulinate under mild reaction conditions (ambient H2 pressure). Among the various catalysts, 2.5% Ru/TiO₂ catalyst showed the maximum catalytic activity of 79% ethyl levulinate (EL) conversion with 82% selectivity of γ-valerolactone (GVL). The recyclability test revealed that the most active 2.5% Ru/TiO₂ also showed the highest stability of the catalyst under optimized experimental conditions.

The widespread application of artificial superhydrophobic material is hindered by the poor durability and regeneration of artificial superhydrophobicity. The problem is expected to be resolved by endowing the superhydrophobic material with self-similarity. Herein, Copper-based superhydrophobic material intensified by furfuryl alcohol resin (Cu/FAR) with long-term durability and high strength is developed, and the obtained Cu/FAR composite reveals excellent and durable superhydrophobicity. Moreover, it is a remarkable fact that the as-prepared superhydrophobic Cu/FAR exhibits outstanding durability and maintenance of superhydrophobicity grounded on the good self-similarity in micro-structure, chemical structure and composition both externally and internally. Consequently, the superhydrophobicity can be maintained or regenerated without difficulty even if superhydrophobic surface has been damaged or fouled accidentally. Therefore, the method provides a new thought to prepare superhydrophobic material with robust durability and outstanding maintenance.

Chitosan (CS), the only alkaline polysaccharose available in nature, has always been a promising candidate for drug delivery owing to its excellent biodegradability and biocompatibility. However, inherent solubility and polycationic properties of CS largely hinder electrospinning, which is an efficient method of fabricating nanofibers for drug carriers. To solve this problem and extend the applications of CS, polyamide/chitosan/tetraethyl orthosilicate (PA/CS/TEOS) composite nanofibers were successfully prepared as drug carriers in this study via electrospinning. The PA/CS/TEOS ratios significantly influenced the nanofiber morphology. As the content of each was increased, the beads among the membranes increased initially and then decreased, determined by scanning electron microscopy (SEM). The morphology of the optimum membranes with the ratio of 1:0.13:0.67 was smoother with less beads and uniform fiber diameter. Finally, the membranes with optimum ratios were used as carriers of ofloxacin in the study of drug release performance to identify their future feasibility, which revealed an initial fast release followed by a relatively stable release.

Studies on fabricating robust superhydrophobic surfaces by a low-cost method have been rare, despite the recent demand for nature-inspired superhydrophobic surfaces including self-healing ability in various industrial applications. Herein, we propose a fabrication method for self-healable, robust superhydrophobic nanocomposite films by facile solution-processed spray coating and UV curing. The components of the coating solution include functionalized hydrophobic silica nanoparticles for producing high roughness hierarchical textured structures with low surface energy, and UV-crosslinkable v-POSS and bi-thiol hydrocarbon molecules to improve the film stability. As a result of the synergetic effect of the hydrophobic nanoparticles and UV-crosslinked polymeric compounds, the spray-coated and UV-cured nanocomposite films possess excellent superhydrophobicity (water contact angles > 150º) and high stability, in addition to self-healing abilities.

With the rapid development of the electronics industry, electronic products based on silicon and glass substrates electronic products will gradually be unable to meet the rising demand. Flexibility, environmental protection, and low costs are important for the development of electronic products. In this study, an efficient and low-cost method for preparing silver electrode structures by direct writing on paper has been demonstrated. Based on this method, a flexible paper-based sensor was prepared. The liquid printing ink used mainly comprises a precursor liquid without pre-prepared nanomaterials. The precursor liquid is transparent with good fluidity. Simple direct writing technology was used to write on the paper substrate using the precursor ink. When the direct-writing paper substrate was subsequently heated, silver nanostructures precipitated from the precursor liquid ink onto the paper substrate. The effect of different temperatures on the formation of the silver nanostructures and the influence of different direct writing processes on the structures were studied. Finally, a paper-based flexible sensor was prepared for finger-bending signal detection. The method is simple to operate and low in cost and can be used for the preparation of environment-friendly paper-based devices.

The optical properties of InGaN/GaN green light-emitting diodes (LEDs) with an undoped graded short-period superlattice (GSL) and a Si-doped GSL (SiGSL) were investigated using photoluminescence (PL) and time-resolved PL spectroscopies. For comparison, an InGaN/GaN conventional LED (CLED) without the GSL structure was also grown. The SiGSL sample showed the strongest PL intensity and the largest PL peak energy because of band-filling effect and weakened quantum- confined stark effect (QCSE). PL decay time of SiGSL sample at 10 K was shorter than those of the CLED and GSL samples. This finding was attributed to the oscillator strength enhancement by the reduced QCSE due to the Coulomb screening by Si donors. In addition, the SiGSL sample exhibited the longest decay time at 300 K, which was ascribed to the reduced defect and dislocation density. These results indicate that insertion of the Si-doped GSL structure is an effective strategy for improving the optical properties in InGaN/GaN green LEDs.

In this study, we added ZrO₂ and Y₂O₃ to stabilize the anatase TiO₂ phase at higher temperatures. Composite mesoporous TiO₂/ZrO₂/Y₂O₃ (TZY) oxides were prepared by a sol-gel method, and triblockcopolymer P123 and PEG was used as templates. The properties of the synthesized materials were characterized using X-Ray diffraction (XRD), Raman scattering, N₂ adsorption/desorption, and UV-Visible spectrophotometry (UV-Vis) methods et al. The samples prepared using P123 and PEG as double-template exhibited smaller particles and a higher specific surface area than the samples prepared using P123 and PEG as single-template. Furthermore, crystal phase transition from anatase to rutile occurred later in the case of the double-template method. After introducing ZrO ₂and Y₂O₃, the crystal phase transition and the growth of crystallites were severely suppressed. The results indicated that the RhB degradation efficiency for the double-template method was 99.24%, while the RhB degradation efficiency with TZY/P123 and TZY/PEG samples was 97.43 and 98.18%, respectively.

Hormones are a dangerous group of molecules that can cause harm to humans. This study based on classical molecular dynamics proposes the nanofiltration of wastewater contaminated by hormones from a computer simulation study, in which the water and the hormone were filtered in two single-walled nanotube compositions. The calculations were carried out by changing the intensities of the electric field that acted as a force exerting pressure on the filtration along the nanotube, in the simulation time of 100 ps. The hormones studied were estrone, estradiol, estriol, progesterone, ethinylestradiol, diethylbestrol, and levonorgestrel in carbon nanotubes (CNTs) and boron nitride (BNNTs). The most efficient nanofiltrations were for fields with low intensities in the order of 10-8 au and 10-7 au. The studied nanotubes can be used in membranes for nanofiltration in water treatment plants due to the evanescent field potential caused by the action of the electric field inside. Our data showed that the action of EF in conjunction with the van der Walls forces of the nanotubes is sufficient to generate the attractive potential. Evaluating the transport of water molecules in CNTs and BNNTs, under the influence of the electric field, a sequence of simulations with the same boundary conditions was carried out, seeking to know the percentage of water molecules filtered in the nanotubes.

In order to understand toxicity of nano silver, human hepatocellular carcinoma (HepG2) cells were treated either with silver nitrate (AgNO₃) or with nano silver capped with glutathione (Ag-S) at various concentration. Differentially expressed genelists for mRNA and microRNA were obtained through Illumina RNA sequencing and DEseq data analyses. Both treatments showed non-linear dose response relationships for mRNA and microRNA. Gene expression analysis showed signaling pathways common to both nano Ag-S and AgNO₃, such as cell cycle regulation, DNA damage response and cancer related pathways. But, nano Ag-S caused signaling pathway changes that were not altered by AgNO₃ such as NRF2-mediated oxidative stress response inflammation, cell membrane signaling, and cell proliferation. Nano Ag-S also affected p53 signaling, survival, apoptosis, tissue repair, lipid synthesis, angiogenesis, liver fibrosis and tumor development. Several of the pathways affected by nano Ag-S are hypothesized as major contributors to nanotoxicity. MicroRNA target filter analysis revealed additional affected pathways that were not reflected in the mRNA expression response alone, including DNA damage signaling, genomic stability, ROS, cell cycle, ubiquitination, DNA methylation, cell proliferation and fibrosis for AgNO₃; and cell cycle regulation, P53 signaling, cell proliferation, survival, apoptosis, tissue repair and so on for nano Ag-S. These pathways may be mediated by microRNA repression of protein translation.Our study clearly showed that the addition of microRNA profiling increased the numbers of signaling pathways discovered that affected by the treatments on HepG2 cells and gave US a better picture of the effects of these reagents in the cells.

The authors report the preparation of the nanocomposite comprising of vanadium pentoxide (V₂O₅) and selenium (Se) nanoparticles and functionalized multiwalled carbon nanotubes (MWCNTs) (V₂O₅@Se NPs/MWCNTs). Since Se NPs possesses extraordinary physicochemical properties including larger surface area with higher adsorption capacity, V₂O₅ NPs were adsorbed onto Se NPs surface through physisorption process (designated as V₂O₅@Se NPs). The nanocomposite synthesized hydrothermally was evaluated for its antimicrobial activity. The morphology and microstructure of the nanocomposite were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, respectively. Fourier transform infrared spectroscopy (FTIR) and UV-Visible spectroscopy (UV-Vis) were employed to analyze the spectral properties of nanocomposite. The microbicidal efficacy of nanocomposite was tested against Gram-negative (G-)ZGram-positive (G+) bacteria and fungus. This is the first report on the synthesis of V₂O₅@Se NPs/MWCNTs nanocomposites by chemical method that showed microbicidal effect on micro-organisms. The thiol (-SH) units facilitates the enrichment of V₂O₅@Se NPs onto MWCNTs surface. Ultimately, it reflects on the significant antimicrobial activity of V₂O₅@Se NPs/MWCNTs.