Search

In the current investigation, zinc oxide (ZnO) nanoparticles and Fe-doped ZnO nanoparticles were sustainably synthesized utilizing an extract derived from the Rumex dentatus plant through a green synthesis approach. The Scanning electron microscope (SEM), X-ray diffraction (XRD), Energy-dispersive x-ray spectroscopy (EDX), Ultra-violet visible spectroscopy (UV–vis) spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and Thermogravimetric analysis (TGA) techniques were used to examine the compositional, morphological, optical, and thermal properties of both samples. The doping of iron into ZnO NPs has significantly influenced their properties. The analysis firmly established that both ZnO NPs and Fe-doped ZnO NPs have hexagonal wurtzite structures and spherical shapes by XRD and SEM. The EDX analysis suggests that iron atoms have been successfully integrated into the ZnO lattice. The change in color observed during the reaction indicated the formation of nanoparticles. The UV–vis peaks at 364 nm and 314 nm confirmed the presence of ZnO NPs and Fe-doped ZnO NPs, respectively. The band gap of ZnO NPs by Fe dopant displayed a narrowing effect. This indicates that adding iron ions to ZnO NPs offers a control band gap. The thermal study TGA revealed that Fe-doped ZnO NPs remain stable when heated up to 600 °C. The antibacterial efficacy of ZnO NPs and Fe-doped ZnO NPs was evaluated against several bacterial strains. The evaluation is based on the zone of inhibition (ZOI). Both samples exhibited excellent antibacterial properties as compared to conventional pharmaceutical agents. These results suggest that synthesizing nanoparticles through plant-based methods is a promising approach to creating versatile and environmentally friendly biomedical products. [ABSTRACT FROM AUTHOR]

Non-enzymatic screen-printed chemiresistive interdigitated electrodes (SPCIE) were designed and fabricated using a low-cost screen-printing method for detection of the glucose. The interdigitated electrodes (IDE) pattern was printed using conductive graphene ink on the glossy surface of the photo paper. The proposed glossy photo paper-based SPCIE are functionalized with multi-walled carbon nanotubes-zinc oxide (MWCNTs-ZnO) nanofibers to create the chemiresistive matrix. Further, to bind these nanofibers with the graphene electrode surface, we have used the green synthesized silver nanoparticles (AgNPs) with banana flower stem fluid (BFSF) as a binder solution. AgNPs with BFSF form the conductive porous natural binder layer (CPNBL). It does not allow to increase the resistivity of the deposited material on graphene electrodes and also keeps the nanofibers intact with paper-based SPCIE. The synthesized material of MWCNT-ZnO nanofibers and green synthesized AgNPs with BFSF as a binder were characterized by Ultraviolet-visible spectroscopy (UV–vis), scanning electron microscope (SEM), x-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The amperometric measurements were performed on the proposed SPCIE sensor to detect the glucose sample directly. The innovative paper-based SPCIE glucose sensor exhibits a linear corelation between current measurements and glucose concentration in the range between 45.22 μ m and 20 mm, with a regression coefficient (R 2) of 0.9902 and a lower limit of detection (LoD) of 45.22 μ m (n = 5). The sensitivity of the developed SPCIE sensor was 2178.57 μ AmM−1cm−2, and the sensor's response time determined was approximately equal to 18 s. The proposed sensor was also tested for real blood serum sample, and relative standard deviation (RSD) was found equal to 2.95%. [ABSTRACT FROM AUTHOR]

The micro-sized hole is highly required in biomedical, electronics, optical, aerospace components that are not feasible by the traditional machining process. This study highlights the precise micromachining on the polymer nanocomposites modified by graphene nanoplatelet (GNP) and carbon fiber. The electric discharge machining (EDM) of polymeric composites is too complicated due to its lower conductivity and abrasive nature. The little concentration of GNP in the epoxy matrix expands the machinability aspect of the polymers. The reinforcing conductive particle is used for the micro EDM (μEDM) of the laminate nanocomposites with a rotating tool electrode. The Taguchi concept-based orthogonal array was used to execute the machining test. The material removal rate (MRR) during the μEDM of the developed laminate nanocomposites was estimated using the sine cosine algorithm. The tests were conducted at three levels of process constraints: voltages, length of the pulses, and weight % of the GNP. The higher value of MRR is obtained at the optimal condition of voltage at three level, length of pulse two level, and weight % of GNP three level. The quality of the machined hole and the surface damages during the machining test were investigated by a field electron scanning electron microscope. The microscopy findings reveal that GNP addition significantly influences the nanocomposite micromachining. [ABSTRACT FROM AUTHOR]

Nanostructure morphologies of transition metal dichalcogenides (TMDs) are gaining much interest owing to their catalytic, sensing, and energy storage capabilities. Here, we report the synthesis of highly dense MoO2/MoS2 core–shell nanoparticles, a new form of TMD nanostructure, via chemical vapor deposition using new growth geometry where a thin film of MoO3 was used as a source substrate for Mo as opposed to using MoO3 powder used in conventional studies. To grow the MoO2/MoS2 core–shell nanoparticles, we precisely control the carrier gas flow rate and sulfur vapor introduction time with respect to the melting of a MoO3 thin film used for Mo precursor. Scanning electron microscope image shows dense coverage of nanoparticles of 50–120 nm in size. The transmission electron microscopy image shows that the nanoparticles consist of crystalline MoO2 core covered with a few layer MoS2 shell. Raman and energy dispersive spectroscopy characterizations further confirm the chemical composition of the nanoparticle containing MoO2 and MoS2. We discuss the growth conditions under which the nanoparticles grow and elucidate its growth mechanism. We also discuss how a small but controllable changes in growth condition could lead to other highly dense growth of vertical/lateral MoO2/MoS2 plates in both source and growth substrates due to the unique growth geometry used in this study. [ABSTRACT FROM AUTHOR]

We performed cathodoluminescence (CL) spectroscopy and imaging in a high-resolution scanning electron microscope to locally and selectively excite and investigate the plasmonic properties of a multi-branched gold nanostar on a silicon substrate. This method allows us to map the local density of optical states from the nanostar with a spatial resolution down to a few nanometers. We resolve, both in the spatial and spectral domain, different plasmon modes associated with the nanostar. Finite-difference time-domain (FDTD) numerical simulations are performed to support the experimental observations. We investigate the effect of the substrate on the plasmonic properties of these complex-shaped nanostars. The powerful CL-FDTD combination helps us to understand the effect of the substrate on the plasmonic response of branched nanoparticles. [ABSTRACT FROM AUTHOR]

Electric field-induced concentration has the potential for application in highly sensitive detection of nanoparticles (NPs) for disease diagnosis and drug discovery. Conventional two-dimensional planar electrodes, however, have shown limited sensitivity in NP concentration. In this paper, the dielectrophoretic (DEP) concentration of low-abundance NPs is studied using a nanostructured tip where a high electric field of 3 × 107 V m−1 is generated. In experimental studies, individual 2, 10, and 100 nm Au NPs are concentrated to a nanotip using DEP concentration and are detected by scanning transmission and scanning electron microscopes. The DEP force on Au NPs near the end of a nanotip is computed according to the distance, and then compared with Brownian motion-induced force. The computational study shows qualitative agreement with the experimental results. When the experimental conditions for DEP concentration are optimized for 8 nm-long oligonucleotides, the sensitivity of a nanotip is 10 aM (10 attomolar; nine copies in a 1.5 μl sample volume). This DEP concentrator using a nanotip can be used for molecular detection without amplification. [ABSTRACT FROM AUTHOR]

In this work, a flash-light sintering process for Cu nanoinks was studied. In order to precisely monitor the milliseconds flash-light sintering process, a real-time Wheatstone bridge electrical circuit and a high-rate data acquisition system were used. The effects of several flash-light irradiation conditions (irradiation energy, pulse number, on-time, and off-time) and the effects of the amount of poly(N-vinylpyrrolidone) in the Cu nanoink on the flash-light sintering process were investigated. The microstructures of the sintered Cu films were analyzed by scanning electron microscopy. To investigate the oxidation or reduction of the oxide-covered copper nanoparticles, a crystal phase analysis using x-ray diffraction was performed. In addition, the sheet resistance of Cu film was measured using a four-point probe method. From this study, it was found that the flash-light sintered Cu nanoink films have a conductivity of 72 Ωm/sq without any damage to the polyimide substrate. Similar nanoinks are expected to be widely used in printed and flexible electronics products in the near future. [ABSTRACT FROM AUTHOR]

An activated-carbon (AC) assisted route is developed to synthesize a ZnO nanoparticle network. The route involves simple addition of AC to the solution containing the zinc salt and finally removing them by burning at higher temperature to form a sponge-like porous ZnO nanoparticles. The surface area measurements show that AC-assisted ZnO nanoparticles (AC-ZnO) have a higher surface area than those synthesized without AC (B-ZnO), which is further confirmed by the field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM) images. Ultraviolet (UV) absorbance results show that the optical quality remains almost unchanged for both types of nanoparticles. Enhanced and faster UV photosensitivity has been observed for the AC-ZnO. The change in the UV photosensing properties demonstrated here provides a new approach to synthesizing other high surface area materials for novel physical and chemical properties. [ABSTRACT FROM AUTHOR]

Regular lattices of polystyrene (PS) microspheres formed by self-assembly processes were used for single-shot fabrication of large regular arrays of nanoparticles or nanobumps or nanoholes on Si surfaces. The morphologies of created nanofeatures were characterized by an atomic force microscope (AFM) and a scanning electron microscope (SEM). The near-field enhancements under the absorptive PS microsphere were studied and calculated. The ablation and thermal processes induced both by laser irradiation of the top surface of the PS microspheres and by the near-field enhancements underneath the microspheres were investigated. When the laser fluence was at a low value of 40 mJ cm?2, periodic PS nanoparticle arrays were produced. With a laser fluence in the range of 100-170 mJ cm?2, regular conical and circular-crater-shaped Si nanobump arrays were fabricated. When the laser fluence was high, up to 200 mJ cm?2, hole arrays were formed in the Si substrate. The mechanisms of this nanofabrication are discussed. Experimental results are explained and are consistent with those of theoretical calculations. [ABSTRACT FROM AUTHOR]