Electron Microscope
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Author(s):  
Katrin Weise ◽  
Thomas Kurth ◽  
Irina Politowski ◽  
Carola Winkelmann ◽  
Andreas Schäffer ◽  
...  

Abstract Although the development and application of nanomaterials is a growing industry, little data is available on the ecotoxicological effects on aquatic organisms. Therefore, we set up a workflow to address the potential uptake of weathered multi-walled carbon nanotubes (wMWCNTs) by a model organism, the pulmonary mud snail Lymnaea stagnalis (L. stagnalis), which plays an important role in the food web. It represents a suitable organism for this approach because as a grazer it potentially ingests large amounts of sedimented wMWCNTs. As food source for L. stagnalis, benthic biofilm was investigated by the use of a transmission electron microscope (TEM) and a scanning electron microscope (SEM) after exposure with wMWCNTs. In addition, isotopic labeling was applied with 14C-wMWCNTs (0.1 mg/L) to quantify fate, behavior, and enrichment of 14C-wMWCNTs in benthic biofilm and in L. stagnalis. Enrichment in benthic biofilm amounted to 529.0 µg wMWCNTs/g dry weight and in L. stagnalis to 79.6 µg wMWCNTs/g dry weight. A bioconcentration factor (BCF) for L. stagnalis was calculated (3500 L/kg). We demonstrate the accumulation of wMWCNTs (10 mg/L) in the digestive tract of L. stagnalis in an effect study. Moreover, the physiological markers glycogen and triglycerides as indicators for the physiological state, as well as the RNA/DNA ratio as growth indicator, were examined. No significant differences between exposed and control animals were analyzed for glycogen and triglycerides after 24 days of exposure, but a decreasing trend is recognizable for triglycerides. In contrast, the significant reduction in the RNA/DNA ratio of L. stagnalis indicated an inhibition of growth with a following recovery after depuration. The described workflow enables a comprehensive determination of the fate and the behavior of wMWCNTs specifically and in general all kinds of CNTs in the aquatic environment and therefore contributes to a holistic risk assessment of wMWCNTs.


2021 ◽  
Vol 8 ◽  
Author(s):  
Simona Aracri ◽  
Marco Contardi ◽  
Ilker S. Bayer ◽  
Muhammad Zahid ◽  
Francesco Giorgio-Serchi ◽  
...  

In response to the pervasive anthropogenic pollution of the ocean, this manuscript suggests the use of biodegradable elastomers in marine applications. The present study characterizes 25 samples of highly biodegradable polymers, obtained blending a base elastomer with natural fibers. Mechanical analysis and Scanning Electron Microscope imaging, reveal how base polymers behave differently depending on the plant fiber chosen, on the external forcing—exposure to water—and on the doses that constitute the final biocomposite. Results suggest that EcoflexTM 00-30 and EcoflexTM 00-50, mixed with potato starch, perform best mechanically, maintaining up to 70% of their maximum tensile strain. Moreover, early signs of degradation are visible on polysiloxane rubber blended with 50% vegetable fibers after 19 hours in distilled water. Analyses demonstrate that highly biodegradable elastomers are good candidates to satisfy the requirements of aquatic devices. Furthermore, the discussed materials can improve the dexterity and biodegradability of marine technology.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Dongmei Mo ◽  
Xiangying Li ◽  
Yong Chen ◽  
Yang Jiang ◽  
Chunfang Gan ◽  
...  

AbstractNanopesticide is one of the best pesticide formulation technologies to overcome the disadvantages of traditional pesticides, which has received great attention from the international community. Using high-speed emulsification and ultrasonic dispersion technology, an avermectin nano-delivery system (Av-NDs) with a particle size of 80–150 nm was prepared through embedding the pesticide molecule utilizing the cross-linking reaction between sodium lignosulfonate and p-phenylenediamine diazonium salt. The formulation and composition of Av-NDs were optimized, the morphology of Av-NDs was analyzed by scanning electron microscope, transmission electron microscope and dynamic light scattering, and the structure of Av-NDs was characterized by UV, IR and 1H NMR. Anti-photolysis and controlled-release tests show that the stability of Av-NDs is 3–4 times of the original avermectin (Av) and possesses the pH-responsive controlled release property. Furthermore, the insecticidal activity of Av-NDs is better than that of avermectin suspension concentrate (Av-SC). The Av-NDs with anti-photolysis and controlled-release characteristics is suitable for large-scale industrial production and is capable to be utilized as effective insecticide in the field.


2021 ◽  
Vol 11 (23) ◽  
pp. 11394
Author(s):  
Ahmed M. Abbas ◽  
Sabah A. Hammad ◽  
Heba Sallam ◽  
Lamiaa Mahfouz ◽  
Mohamed K. Ahmed ◽  
...  

This paper reports on the manufacture of ZnO nanoparticles (ZnO NPs) from Prosopis juliflora leaf extracts. Various methods of characterization were used, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and transmission electron microscope TEM. ZnO NPs has a hexagonal wurtzite structure with a preferred orientation of 101 planes, according to XRD. The functional groups found in ZnO NPs isolated from leaves are responsible for the FT-IR peaks that correspond to them. The morphology of the produced nanoparticles is a sphere-like form, as shown in the SEM pictures. TEM examination revealed ZnO NPs with a size of 50–55 nm. These ZnO NPs were used to remediate pollutants in paper mill effluents, and they were able to remove 86% of the organic pollutants from the sample at 0.05 mg/L dose and reduce 89% of the organic pollutants during a 5-h reflex time. Meanwhile, for the photocatalysis of paper mill effluents, it has been noted that COD was removed by 74.30%, 63.23%, and 57.96% for the first, second, and third cycles, respectively.


2021 ◽  
Author(s):  
Sina Karimi ◽  
Hamed Farshbaf Aghajani

Abstract This paper aims to achieve a specific type of cemented sand-gravel mixtures with low permeability to implement in the impervious zone of hardfill dams. To this end, various mixtures are prepared by blending two native soils of sand and gravel with different amounts of kaolinite or bentonite additives in presence of various cement content. The compaction properties, uniaxial compressive strength, permeability and scanning electron microscope (SEM) images of mixtures are measured. According to the results, the cemented mixture containing 10% of kaolinite additive regardless of native soil type exhibits the maximum strength. However, the bentonite disturbs the cement hydration in the mixture, and the strength of mixtures especially with high cement content decreases with increasing the bentonite content. The permeability of mixtures is related to the amount of cement and fine additive in the mixture. The permeability of both cemented sand and gravel mixtures decreases with increasing the bentonite additive. However, the kaolinite additive has a limited influence on the permeability of cemented gravel mixtures. The lowest permeability is achieved in the mixture involving the higher amount of bentonite (with a weight ratio of 30%) in presence of adequate cement.


2021 ◽  
Vol 105 (1) ◽  
pp. 355-369
Author(s):  
Tomáš Binar ◽  
Jana Zimáková ◽  
Jakub Steiniger ◽  
Lukáš Řehořek ◽  
Petr Křivík ◽  
...  

A layer of copper was applied to the base aluminum material using the cold spray method (cold kinetic deposition). The samples were exposed to corrosion in a salt chamber for 100, 200 and 300 hours. The change in the size of the internal and surface resistance of the samples was monitored. The corrosion results were also examined using an electron microscope.


2021 ◽  
Vol 105 (1) ◽  
pp. 431-440
Author(s):  
Pavel Šafl ◽  
Jana Zimáková ◽  
Tomáš Binar

The aim of this work is to study the climatic influences on 3D printed materials. This study focuses on the HIPS material, which was chosen as the starting material for further studies. The material in the field of 3D printing is known for its rapid photooxidation, which results in the formation of cracks in the final product. A climatic chamber was used for degradation, in which UV light, heat and increased humidity were applied to the material. The degree of degradation was then checked by tensile test and electron microscope.


2021 ◽  
Vol 105 (1) ◽  
pp. 589-599
Author(s):  
Jiří Maxa ◽  
Pavla Šabacká ◽  
Robert Bayer

As part of the research in the field of vacuum chamber pumping in the Environmental Electron Microscope, research on supersonic flow through apertures is being carried out at the Department of Electrical and Electronic Technology of Brno University of Technology in cooperation with the Institute of Scientific Instruments of the CAS. This paper deals with the influence of reflected shock waves on the resulting flow in the pumped part of the Experimental Chamber.


2021 ◽  
Vol 105 (1) ◽  
pp. 627-635
Author(s):  
Pavla Šabacká ◽  
Jiří Maxa ◽  
Anna Maxová

As part of the research in the field of pumping vacuum chambers in the Environmental Electron Microscope, research on supersonic flow through apertures is being carried out at the Department of Electrical and Electronic Technology of the Brno University of Technology in cooperation with the Institute of Scientific Instruments of the CAS. This paper deals with the influence of the shape of the static probe cone design for static pressure measurements in the supersonic flow regime in the Experimental Chamber. The cone of the probe has an effect on the shape of the shock wave, which significantly influences the detected static pressure value.


2021 ◽  
Vol 105 (1) ◽  
pp. 601-608
Author(s):  
Robert Bayer ◽  
Anna Maxová

As a part of the research in the field of pumping vacuum chambers in the Environmental Electron Microscope, a research on supersonic flow through the Appertures is being carried out at the Department of Electrical and Electronic Technology of the Brno University of Technology in cooperation with the Institute of Scientific Instruments of the Czech Academy of Science. This paper deals with the possibility of investigating shock waves using the Shlieren optical method, which allows to observe pressure gradients as the first derivation of pressure.


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