Low Resolution Transmission Electron Microscopy Research Articles

Harnessing hyperaccumulator (Brassica oleracea var. alboglabra) extract for green synthesis of nickel oxide nanoparticles: A prospective route for post-phytoremediation

Even though phytoremediation is considered a green technology for remediating heavy metals, there are some problems with the application of this technology, particularly when it comes to managing the biomass that is used. So, processing biomass needs to be given a lot of attention. This study outlined the utilization of extracts obtained from the hyperaccumulator plant Brassica oleracea var. alboglabra to synthesize nickel oxide nanoparticles. Subsequently, the nanoparticle underwent testing to determine its suitability as an absorbent for heavy metals, specifically lead, as well as its efficacy as an antifungal agent against Fusarium sp. strain. The characterization of nickel oxide nanoparticles involved several measurements, such as scanning electron microscopy analysis, high- and low-resolution transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and hysteresis curve acquisition. The research findings indicate that the extract from hyperaccumulators can be utilized for the synthesis of NiO, which exhibits an absorption capacity exceeding 98% and serves as an efficient antifungal agent against Fusarium sp. pathogens. The approach utilized in this study not only prioritizes "green" and sustainability factors but also takes into account the economic aspects associated with the items being manufactured. The research has important implications in two areas. Firstly, it demonstrates the utilization of natural resources (B. oleracea var. alboglabra) in the production of nickel oxide, which serves as a safer and more eco-friendly substitute for dangerous chemicals. Furthermore, it aids in the advancement of novel techniques for effectively managing biomass hyperaccumulators.

Understanding the Influence of Receptive Field and Network Complexity in Neural Network-Guided TEM Image Analysis.

Trained neural networks are promising tools to analyze the ever-increasing amount of scientific image data, but it is unclear how to best customize these networks for the unique features in transmission electron micrographs. Here, we systematically examine how neural network architecture choices affect how neural networks segment, or pixel-wise separate, crystalline nanoparticles from amorphous background in transmission electron microscopy (TEM) images. We focus on decoupling the influence of receptive field, or the area of the input image that contributes to the output decision, from network complexity, which dictates the number of trainable parameters. For low-resolution TEM images which rely on amplitude contrast to distinguish nanoparticles from background, we find that the receptive field does not significantly influence segmentation performance. On the other hand, for high-resolution TEM images which rely on both amplitude and phase-contrast changes to identify nanoparticles, receptive field is an important parameter for increased performance, especially in images with minimal amplitude contrast. Rather than depending on atom or nanoparticle size, the ideal receptive field seems to be inversely correlated to the degree of nanoparticle contrast in the image. Our results provide insight and guidance as to how to adapt neural networks for applications with TEM datasets.

A composite film prepared from titanium carbide Ti3C2Tx (MXene) and gold nanoparticles for voltammetric determination of uric acid and folic acid

In this study, a solution-processing based galvanic deposition approach is described for in-situ deposition of gold nanoparticles (AuNP) on delaminated titanium Ti3C2Tx nanosheets under ultrasonication. The nanocomposite (AuNP@Ti3C2Tx) was placed on a glassy carbon electrode (GCE) and then applied to electrochemically with label-free, and simultaneously sense uric acid (UA), and folic acid (FA) at physiological pH. The modified GCE has attractive figures of merit: (i) The working potentials for UA and AA are well separated (+0.35V and 0.70V vs. Ag|AgCl); (ii) wide linear responses (from 0.03-1520μM for UA and from 0.02-3580μM for FA; (iii) good electrochemical sensitivities for both UA and FA (0.53 and 0.494μAμM-1.cm-2, respectively), and (iv) detection limits of 11.5nM (UA) and 6.20nM (FA). The electrode exhibited good repeatability (RSD = 4.4%), acceptable reproducibility (RSD = 4.1%), and excellent stability (91.8% over one-month storage). The method was applied to analyze spiked serum samples, and modified GCE is shown appreciable recoveries (97.1-98.8% and 96.8-98.0% for UA, and FA, respectively). Graphical abstractA photograph (top left) of colloidal suspension of gold nanoparticles (AuNPs). They were grown onthe delaminated titanium carbide Ti3C2Tx MXenenanosheet via galvanic displacement deposition method, and their corresponding a low-resolution transmission electron microscopy micrograph (top right) of AuNP@Ti3C2Tx. The graphical representation of AuNP@Ti3C2Tx drop-casted on glassy carbon electrode (GCE) (bottom left), and their voltammetric measurement were applied in the presence of both uric acid and folic acid with increasing the concentration of both analytes (bottom right).

Remarkable Ti-promotion in vanadium doped anatase titania for methylene blue adsorption in aqueous medium

We report here the synthesis of vanadium (5–20 at.%) doped titania and the pristine oxides via surfactant assisted coprecipitation method using cetyltrimethylammonium bromide as the surfactant and investigated their adsorption behavior towards hazardous methylene blue dye. The formation of anatase phase in all the doped materials is confirmed by the powder x-ray diffraction (P-XRD) analysis as corroborated by the Fourier transform-infrared (FT-IR) analysis, with particle sizes in the range 8–11 nm. Pure titania doesn’t show any adsorption property, but its presence enhances the adsorption property of vanadia considerably suggesting a promoting role of titania in the doped materials. The 10 at.% V-doped material, V0.1Ti0.9O2 is found to exhibit the best adsorption behaviour. The low resolution transmission electron microscopy studies reveal homogeneous nature, while ring type electron diffraction pattern suggests polycrystalline nature of the material. The high resolution transmission electron microscopy analysis suggests formation of single phase oxide. Kinetic and equilibrium studies have revealed the pseudo-second-order kinetics and Langmuir isotherm nature for this physisorption process. The pH dependency and recycling ability of this material have been discussed. Finally, X-ray photoelectron spectroscopy, FT-IR and P-XRD studies have been applied to understand the mechanism of regeneration of the material.

Identification and characteristics of core–shell ZnO/ZnO:Mg nanorods synthesized by hydrothermal method

This study successfully synthesized the first core–shell ZnO/Mg doped ZnO (ZnO:Mg) nanorod arrays on p-silicon (100) substrates using the simple hydrothermal method. The vertically aligned synthesized ZnO nanorod arrays served as a template for the growth of 1.75 atomic% Mg doped ZnO. The morphological, structural, and optical features of the nanorod arrays were characterized using microscopic and spectroscopic techniques. The FESEM micrographs showed that diameter of the core is approximately 50 nm encapsulated by shell with thickness of about 30 nm. The low-resolution transmission electron microscopy images showed distinctive morphologies of the core and shell layers. Raman spectroscopy measurements provided structural evidence for the formation of a core–shell ZnO/ZnO:Mg nanorod arrays. The photoluminescence spectra of the core–shell ZnO/ZnO:Mg exhibited an intense sharp peak near-band-edge emission with splitting at 376 and 384 nm, with very weak and negligible defect emission at around 520 nm. Increase in the intensity ratio of the IUV/IVIS emission by three confirmed the relatively enhanced optical properties compared with that of core (ZnO) nanorod arrays.

Toxicity of single-wall carbon nanotubes functionalized with polyethylene glycol in zebrafish (Danio rerio) embryos.

Single-wall carbon nanotubes functionalized with polyethylene glycol (SWCNT-PEG) are promising materials for biomedical applications such as diagnostic devices and controlled drug-release systems. However, several questions about their toxicological profile remain unanswered. Thus, the aim of this study was to investigate the action of SWCNT-PEG in Danio rerio zebrafish embryos at the molecular, physiological and morphological levels. The SWCNT used in this study were synthesized by the high-pressure carbon monoxide process, purified and then functionalized with distearoyl phosphatidylethanolamine block copolymer-PEG (molecular weight 2 kDa). The characterization process was carried out with low-resolution transmission electron microscopy, thermogravimetric analysis and Raman spectroscopy. Individual zebrafish embryos were exposed to the SWCNT-PEG. Toxic effects occurred only at the highest concentration tested (1 ppm) and included high mortality rates, delayed hatching and decreased total larval length. For all the concentrations tested, the alkaline comet assay revealed no genotoxicity, and Raman spectroscopy measurements on the histological slices revealed no intracellular nanotubes. The results shown here demonstrate that SWCNT-PEG has low toxicity in zebrafish embryos, but more studies are needed to understand what mechanisms are involved. However, the presence of residual metals is possibly among the primary mechanisms responsible for the toxic effects observed, because the purification process was not able to remove all metal contamination, as demonstrated by the thermogravimetric analysis. More attention must be given to the toxicity of these nanomaterials before they are used in biomedical applications. Copyright © 2016 John Wiley & Sons, Ltd.

Preparation and reactivity of UV light-reduced Pd/α-Fe2O3 catalyst towards the hydrogenation of o-chloronitrobenzene

A type of Pd/α-Fe2O3 catalyst was synthesized by a convenient UV light-induced reduction in the presence of Fe3+ ions. The synthesized Pd/α-Fe2O3 particles were characterized by X-ray diffraction (XRD), low-resolution transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectrum (XPS), atomic force microscope (AFM), scan electron microscopy with energy dispersion spectra (SEM-EDS), FT-IR and BET. Related characterizations confirm that UV light-induced reduction is a feasible, simply and environment-friendly method for the preparation of supported catalysts containing active metal. Furthermore, hydrogenation of o-chloronitrobenzene (o-CNB) to o-chloroaniline (o-CAN) by the selected Pd(0.5%)/α-Fe2O3 was investigated systematically. The α-Fe2O3-supported Pd catalyst was found to exhibit good catalytic activity and selectivity for the o-CNB reduction under mild conditions. The hydrogenation of o-CNB over the resulting Pd-based catalyst gave a 100% o-CNB conversion and 91.4% selectivity of o-CAN under the reaction conditions of 50°C, 2h, 1MPa hydrogen pressure, no-CNB/nPd=6000:1. Moreover, the resulting Pd-based catalyst remained higher hydrogenation reactivity after three runs even if a sharply decrease in activity was observed at the fourth run. The obtained results reveal the as-prepared Pd/α-Fe2O3 is an efficient catalyst for the hydrogenation of o-CNB even at a high level of substrate concentration.

Physical characterization and photoluminescence properties of thioglycolic acid-stabilized lead sulfide nanocrystals

Lead sulfide (PbS) nanocrystals (NCs) were surfactant-free synthesized and stabilized with thioglycolic acid (TGA) by an environmentally friendly and controllable chemical route. Structural, surface morphological, optical and photoluminescence properties of the samples were studied using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), low-resolution transmission electron microscopy (LR-TEM), FT-IR spectroscopy, UV–visible spectroscopy and fluorescence spectroscopy, respectively. The synthesized TGA-PbS NCs showed a well-defined cubic morphology and size monodispersity, as well as good dispersibility in aqueous solution. The optical and photoluminescence study showed that these NCs were very crystalline, size quantized and exhibited a single strong, narrow red emission band centered at λEm = 680 nm. Time evolution of the emission properties was analyzed after six, twelve and twenty four months. The results confirmed that the as-prepared product is photostable when it is kept under storage at 4 °C and has great potential for both biotechnological applications and analytical purposes. A probable chemical stabilization mechanism is proposed.

Direct Evidence for Local Symmetry Breaking during a Strain Glass Transition

Strain glass transition is a unique nanoscale displacive transition with local symmetry breaking while maintaining the macroscopic symmetry or average structure unchanged. It usually occurs in the "nonmartensitic" composition range of a martensitic system. So far, only indirect evidence exists for such a transition, essentially from macroscopic measurements and low-resolution transmission electron microscopy observations, and there is a lack of direct evidence for the speculated local symmetry breaking and the sluggish nature of the glass transition. In this Letter we report in situ high-resolution transmission electron microscopy observations on a Ti50(Pd41Cr9) strain glass alloy and direct evidence for these key issues. Our results show that at temperatures well above the strain glass transition temperature (Tg), the lattice is essentially an undistorted B2 structure. With approaching Tg, the local symmetry breaking gradually occurs with the formation and growth of nanomartensite clusters with a combined stacking period of three and four plane intervals, but the average structure measured by x-ray diffraction remains B2. These nanomartensite clusters become finally frozen below Tg. Our results provide not only a microscopic basis for the macroscopic properties of strain glass, but also new insights into a range of possible applications of this unique class of materials.

Porphyrin Assemblies via a Surfactant-Assisted Method: From Nanospheres to Nanofibers with Tunable Length

In this paper, we report that a porphyrin, zinc 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (ZnTPyP), could be organized to form one-dimensional (1D) nanofibers via a surfactant-assisted self-assembly (SAS) method. We disclose that when a chloroform solution of ZnTPyP is dropwise added into an aqueous solution of cetyltrimethylammonium bromide (CTAB), spherical nanostructures are formed at the initial stage. The nanospheres are naturally transformed into 1D nanostructures simply by aging under ambient conditions. Interestingly, by adjusting the volume of the employed ZnTPyP chloroform solution, the length of thus-produced 1D nanoarchitectures could be efficiently controlled. It is disclosed that longer nanofibers could be manufactured when a small volume of chloroform solution of ZnTPyP is involved, while shorter 1D nanospecies could be produced when a large volume of chloroform solution of ZnTPyP is employed. The 1D nanostructures are characterized by UV-visible spectra, scanning electron microscopy, low-resolution transmission electron microscopy, high-resolution transmission electron microscopy, and fast Fourier transformation. A solubility experiment has been carried out to disclose the dispersibility of our ZnTPyP in plain water and in CTAB aqueous solution. On the basis of the experimental facts, an explanation is proposed for these interesting new findings. The investigation provides new opportunities for the controllable assembly of porphyrin-based 1D nanomaterials with tunable length, and it sheds new scientific insights on the molecular assembly process occurring in the SAS system, wherein an oil/water system is used as the assembly medium.

High performance PtPdAu nano-catalyst for ethanol oxidation in alkaline media for fuel cell applications

In the present investigation, Vulcan XC-72 supported Pt and Pt based binary and ternary catalysts (Pt/C, PtPd/C, PtAu/C, PtPdAu/C) have been synthesized under borohydride reduction scheme and applied for the study of the electro-oxidation of ethanol in alkaline media at room temperature. The surface morphology of the catalysts was determined by XRD (X-ray diffraction) & TEM (transmission electron microscopy) analysis. XRD patterns reveal that all the catalysts have disordered face center cubic lattice structures. Low resolution TEM images reveal uniform dispersion of metal nano particles on carbon support having an average size of 3–4.5 nm. HRTEM is also carried out for the determination of the distance between the lattice planes. Different textural properties including external surface area, pore volume and widths of the catalyst matrix were calculated by applying the BET equation to the adsorption isotherms. During electrolysis substantial increase in anodic peak current was observed for ethanol oxidations when the second and third metal component was introduced into the Pt matrix as in case of PtPdAu/C catalysts. The charge transfer resistance (Rct) for ethanol oxidation was substantially reduced from 87.9 Ω on Pt/C to 7.74 Ω on PtPdAu/C demonstrating the superior electrode kinetics behavior of the latter over the other catalysts studied. Thus Au and Pd incorporation into the Pt matrix not only increases the catalytic efficiency of the alloyed catalyst but at the same time effectively reduces the Pt content in the ternary system.

Upright-standing ZnO nano-sheets growth using wet chemistry

Abstract Room temperature solution processing is used for cross-linked upright-standing ZnO nano-sheets growth of ∼2–5 μm in length and ∼100–150 nm in width. These nano-sheets are characterized for structural and surface morphological analyses. Energy dispersive X-ray spectrum is preferred to chemical analysis. Confirmation of well defined, cross-linked and distinct ZnO nano-sheets of quoted dimensions is carried out using a scanning electron microscopy. Porous nature of nano-sheets with fine edge boundaries is noted from low resolution transmission electron microscopy.

Microwave Approach for the Synthesis of Rhabdophane‐Type Lanthanide Orthophosphate (Ln: La, Ce, Nd, Sm, Eu, Gd and Tb) Nanorods under Solvothermal Conditions.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Microwave approach for the synthesis of rhabdophane-type lanthanide orthophosphate (Ln = La, Ce, Nd, Sm, Eu, Gd and Tb) nanorods under solvothermal conditions

Rhabdophane-type hexagonal lanthanide orthophosphate, LnPO4·nH2O (Ln = La, Ce, Nd, Sm, Eu, Gd and Tb, n = 0 to 0.6), and body-centered tetragonal ErPO4·nH2O nanowires/nanorods have been successfully synthesized in high yield (>95%) by simple microwave heating of an aqueous solution of Ln(III) nitrate and NH4H2PO4 in the pH range 1.8–2.2. The reaction was conducted in a simple domestic microwave oven. The structure, morphology, composition and physical properties of the as-prepared products have been characterized by powder X-ray diffraction, low resolution transmission electron microscopy, high resolution transmission electron microscopy, selected area electron diffraction, thermogravimetric analysis, differential scanning calorimetry, infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy. The length and width of the resulting lanthanide orthophosphate nanowires/nanorods are in the range 70–2200 nm and 6–130 nm, respectively. A possible mechanism for the formation of LnPO4·nH2O nanowires/nanorods is briefly discussed.

Ultrastructural properties of bone mineral of control and tiludronate-treated osteoporotic rat.

Bisphosphonates have been widely used in the treatment of human bone pathologies including osteoporosis. In this case, bisphosphonates have been shown to reduce bone resorption, thereby increasing the mass and mechanical resistance of bone. Determining the effects of these molecules on the properties of the bone apatite crystals could provide a better insight into the mechanism of bisphosphonate/bone interaction. The aim of this study was to determine the ultrastructural effects of a third generation bisphosphonate (tiludronate) on the morphology, size, distribution, chemical composition, and structure of apatite crystals in bone (trabecular) in a rat osteoporotic model. Four groups of rats were studied: (1) sham operated, (2) untreated ovariectomized (OVX), (3) OVX rats which received 35 mg/kg of tiludronate, (4) OVX rats which received 160 mg/kg of tiludronate. The rats of groups 3 and 4 received tiludronate orally in 2 consecutive days every week for 1 year. Scanning electron microscopy (SEM), high and low resolution transmission electron microscopy (TEM), and electron microprobe analysis (EDX) were used for the ultrastructural characterization of the bone mineral. This study demonstrated that tiludronate slightly increased the width of bone apatite crystals without changing any other crystal characteristics.

Reverse Micelle Synthesis and Characterization of Superparamagnetic MnFe2O4 Spinel Ferrite Nanocrystallites

MnFe2O4 nanoparticles are synthesized by using sodium dodecylbenzenesulfonate (NaDBS) to form water-in-toluene reverse micelles. The nanoparticles are single crystalline, and the average particle size can be controlled from 4 to 15 nm. High- and low-resolution transmission electron microscopy characterization has shown that the nanoparticles can have a size distribution as narrow as ∼9%. Neutron diffraction and magnetic measurements have been conducted on the nanoparticles with a diameter of 7.7 ± 0.7 nm. The results unambiguously prove that these MnFe2O4 nanoparticles are truly superparamagnetic. The synthesis and characterization of these nanoparticles will facilitate the development of MnFe2O4 nanoparticles for the potential applications such as contrast enhancement agents of magnetic resonance imaging and magnetic carriers for site-specific drug delivery.