scholarly journals Degradation of polymers by fungi isolated from dumpsites

2021 ◽  
Author(s):  
Iqra Bashir ◽  
Zafar Iqbal Shams ◽  
Syed Ehteshamul-Haque ◽  
Faizah Urooj ◽  
Hafiza Farhat
Keyword(s):  
Electron Microscopy ◽  
Weight Loss ◽  
Aspergillus Flavus ◽  
Fungal Species ◽  
The Other ◽  
Sem Images ◽  
Fungal Hyphae ◽  
Formation Of Cracks ◽  
Degraded Polymer ◽  
Scanning Electron

Abstract The present study aims at identifying the ability of nine fungal species, which were isolated from garbage of different sites to degrade commonly used polymers, viz. polyethylene, polystyrene, and polyurethane when treated with four methods separately, viz., sterilized and unsterilized drench methods, sterilized and unsterilized mulching methods for four months. All the species considerably degraded the polymers by the above-mentioned methods. However, polystyrene demonstrated the greatest degradation compared to the other two polymers, particularly by sterilized and unsterilized drench methods. Seven fungal species caused greater than 50% weight loss of polystyrene when treated with the above-mentioned methods. Aspergillus flavus instigated the greatest weight loss (74.78 ± 2.85%) by the unsterilized drench method. Of nine, three species caused more than 50% weight loss of polyurethane by the unsterilized drench method. A. niger divulged greater than 50% weight loss of the polymer by sterilized drench method. In this study, polyethylene was found least degraded compared to polystyrene and polyurethane by the selected fungal species. Of nine, only two species, viz. Aspergillus flavus and A. niger caused a higher than 50% weight loss of polyethylene only by sterilized drench method. Scanning Electron Microscopy (SEM) images of six elevated degraded polymer samples were taken to reveal the formation of spores and hyphae on the surface of the plastic. The images demonstrated the formation of cracks and crevices on the surface of different polymers by spores and the fungal hyphae.

scholarly journals The Influence of Laser Defocusing in Selective Laser Melted IN 625

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3447
Author(s):  
Alexandru Paraschiv ◽  
Gheorghe Matache ◽  
Mihaela Raluca Condruz ◽  
Tiberius Florian Frigioescu ◽  
Ion Ionică
Keyword(s):  
Electron Microscopy ◽  
Tensile Testing ◽  
Maximum Density ◽  
The Other ◽  
Melting Depth ◽  
Sem Images ◽  
Pool Shape ◽  
Melt Pool ◽  
Melt Pool Size ◽  
Scanning Electron

Laser defocusing was investigated to assess the influence on the surface quality, melt pool shape, tensile properties, and densification of selective laser melted (SLMed) IN 625. Negative (−0.5 mm, −0.3 mm), positive (+0.3 mm, +0.5 mm), and 0 mm defocusing distances were used to produce specimens, while the other process parameters remained unchanged. The scanning electron microscopy (SEM) images of the melt pools generated by different defocusing amounts were used to assess the influence on the morphology and melt pool size. The mechanical properties were evaluated by tensile testing, and the bulk density of the parts was measured by Archimedes’ method. It was observed that the melt pool morphology and melting mode are directly related to the defocusing distances. The melting height increases while the melting depth decreases from positive to negative defocusing. The use of negative defocusing distances generates the conduction melting mode of the SLMed IN 625, and the alloy (as-built) has the maximum density and ultimate tensile strength. Conversely, the use of positive distances generates keyhole mode melting accompanied by a decrease of density and mechanical strength due to the increase in porosity and is therefore not suitable for the SLM process.

Observation d'un sol forestier (rendzine) en microscopie electronique

1979 ◽  
Vol 25 (8) ◽  
pp. 943-946 ◽  
Author(s):  
G. Kilbertus ◽  
J. Proth
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Forest Soil ◽  
Clay Minerals ◽  
The Other ◽  
Soil Suspension ◽  
Microscopie Électronique ◽  
Fungal Hyphae ◽  
Ultrathin Sections ◽  
Scanning Electron

Scanning electron microscopy was used to evidence the aggregated structure of a forest soil as well as the presence of fungal hyphae external to soil aggregates.The supernatant of soil suspension in water mainly contained isolated bacteria, while ultrathin sections of aggregates frequently revealed groups of bacteria surrounded by a sheath of mucilage with adhering clay minerals on the outside.These results confirm the existence of two particular biotopes in the soil studied: one is located inside aggregates, and the other, in the inter-aggregate spaces. [Translated by the journal]

scholarly journals Microscopy Methods for Biofilm Imaging: Focus on SEM and VP-SEM Pros and Cons

Biology ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 51
Author(s):  
Michela Relucenti ◽  
Giuseppe Familiari ◽  
Orlando Donfrancesco ◽  
Maurizio Taurino ◽  
Xiaobo Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Ion Beam ◽  
Ruthenium Red ◽  
Variable Pressure ◽  
Sem Images ◽  
Advantages And Disadvantages ◽  
Pros And Cons ◽  
Microscopy Techniques ◽  
Scanning Electron

Several imaging methodologies have been used in biofilm studies, contributing to deepening the knowledge on their structure. This review illustrates the most widely used microscopy techniques in biofilm investigations, focusing on traditional and innovative scanning electron microscopy techniques such as scanning electron microscopy (SEM), variable pressure SEM (VP-SEM), environmental SEM (ESEM), and the more recent ambiental SEM (ASEM), ending with the cutting edge Cryo-SEM and focused ion beam SEM (FIB SEM), highlighting the pros and cons of several methods with particular emphasis on conventional SEM and VP-SEM. As each technique has its own advantages and disadvantages, the choice of the most appropriate method must be done carefully, based on the specific aim of the study. The evaluation of the drug effects on biofilm requires imaging methods that show the most detailed ultrastructural features of the biofilm. In this kind of research, the use of scanning electron microscopy with customized protocols such as osmium tetroxide (OsO4), ruthenium red (RR), tannic acid (TA) staining, and ionic liquid (IL) treatment is unrivalled for its image quality, magnification, resolution, minimal sample loss, and actual sample structure preservation. The combined use of innovative SEM protocols and 3-D image analysis software will allow for quantitative data from SEM images to be extracted; in this way, data from images of samples that have undergone different antibiofilm treatments can be compared.

Occurrence of Vesicular-Arbuscular Mycorrhizal Fungi in Alberta, Canada

1993 ◽  
Vol 48 (11-12) ◽  
pp. 923-929 ◽  
Author(s):  
S. M. Boyetchko ◽  
J. P. Tewari
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal ◽  
Fungal Species ◽  
Glomus Aggregatum ◽  
X Ray ◽  
Vesicular Arbuscular ◽  
Spore Walls ◽  
Scanning Electron

Abstract Three V A mycorrhizal fungal species were isolated from soils in Alberta, Canada and examined by scanning electron microscopy and energy-dispersive X-ray microanalysis. Mature spores of Glomus aggregatum developed an outer hyaline wall which contained lower levels of calcium than the middle wall. Examination of G. pansihalos spores revealed a lower level of calcium in the outer evanescent wall as compared to the ornamented wall. When spores of Entrophospora infrequens were examined, the wall of the vesicle was found to contain similar levels of calcium as the ornamented wall of the spore. The significance of the results concerning the presence of calcium in mycorrhizal spore walls is discussed, as is the occurrence of the mycorrhizal species.

Use of electron microscopy to characterize the surfaces of flocculent and nonflocculent yeast cells

1989 ◽  
Vol 35 (12) ◽  
pp. 1081-1086 ◽  
Author(s):  
Byron F. Johnson ◽  
L. C. Sowden ◽  
Teena Walker ◽  
Bong Y. Yoo ◽  
Gode B. Calleja
Keyword(s):  
Electron Microscopy ◽  
Fission Yeast ◽  
Budding Yeast ◽  
The Other ◽  
Yeast Cells ◽  
Scanning Electron Micrographs ◽  
Soft Or ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Scanning Electron

The surfaces of flocculent and nonflocculent yeast cells have been examined by electron microscopy. Nonextractive preparative procedures for scanning electron microscopy allow comparison in which sharp or softened images of surface details (scars, etc.) are the criteria for relative abundance of flocculum material. Asexually flocculent budding-yeast cells cannot be distinguished from nonflocculent budding-yeast cells in scanning electron micrographs because the scar details of both are well resolved, being hard and sharp. On the other hand, flocculent fission-yeast cells are readily distinguished from nonflocculent cells because fission scars are mostly soft or obscured on flocculent cells, but sharp on nonflocculent cells. Sexually and asexually flocculent fission-yeast cells cannot be distinguished from one another as both are heavily clad in "mucilaginous" or "hairy" coverings. Examination of lightly extracted and heavily extracted flocculent fission-yeast cells by transmission electron microscopy provides micrographs consistent with the scanning electron micrographs.Key words: flocculation, budding yeast, fission yeast, scanning, transmission.

scholarly journals Apolar Bioactive Fraction ofMelipona scutellarisGeopropolis onStreptococcus mutansBiofilm

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Marcos Guilherme da Cunha ◽  
Marcelo Franchin ◽  
Lívia Câmara de Carvalho Galvão ◽  
Bruno Bueno-Silva ◽  
Masaharu Ikegaki ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Biofilm Formation ◽  
Microbial Population ◽  
Ethanolic Extract ◽  
Vehicle Control ◽  
Sem Images ◽  
Killing Assay ◽  
Bioactive Fraction ◽  
Biofilm Matrix ◽  
Scanning Electron

The aim of this study was to evaluate the influence of the bioactive nonpolar fraction of geopropolis onStreptococcus mutansbiofilm. The ethanolic extract ofMelipona scutellarisgeopropolis was subjected to a liquid-liquid partition, thus obtaining the bioactive hexane fraction (HF) possessing antimicrobial activity. The effects of HF onS. mutansUA159 biofilms generated on saliva-coated hydroxyapatite discs were analyzed by inhibition of formation, killing assay, and glycolytic pH-drop assays. Furthermore, biofilms treated with vehicle control and HF were analyzed by scanning electron microscopy (SEM). HF at 250 μg/mL and 400 μg/mL caused 38% and 53% reduction in the biomass of biofilm, respectively, when compared to vehicle control (P<0.05) subsequently observed at SEM images, and this reduction was noticed in the amounts of extracellular alkali-soluble glucans, intracellular iodophilic polysaccharides, and proteins. In addition, theS. mutansviability (killing assay) and acid production by glycolytic pH drop were not affected (P>0.05). In conclusion, the bioactive HF of geopropolis was promising to control theS. mutansbiofilm formation, without affecting the microbial population but interfering with its structure by reducing the biochemical content of biofilm matrix.

scholarly journals Effect of Surfactant Addition on Bi2Te3 Nanostructures Synthesized by Hydrothermal Method

2017 ◽  
Vol 62 (2) ◽  
pp. 1005-1010 ◽  
Author(s):  
Peyala Dharmaiah ◽  
C.H. Lee ◽  
B. Madavali ◽  
Soon-Jik Hong
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Method ◽  
Figure Of Merit ◽  
Bulk Sample ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coarse Grains ◽  
Scanning Electron ◽  
Nanostructured Sample

AbstractIn the present work, we have prepared Bi2Te3nanostructures with different morphologies such as nano-spherical, nanoplates and nanoflakes obtained using various surfactant additions (EG, PVP, and EDTA) by a hydrothermal method. The shape of the nanoparticles can be controlled by addition of surfactants. The samples were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). It is found that the minority BiOCl phase disappears after maintained pH at 10 with EG as surfactant. SEM bulk microstructure reveals that the sample consists of fine and coarse grains. Temperature dependence of thermoelectric properties of the nanostructured bulk sample was investigated in the range of 300-450K. The presence of nanograins in the bulk sample exhibits a reduction of thermal conductivity and less effect on electrical conductivity. As a result, a figure of merit of the sintered bulk sample reached 0.2 at 400 K. A maximum micro Vickers hardness of 102 Hv was obtained for the nanostructured sample, which was higher than the other reported results.

scholarly journals Corrosion Inhibitive Action and Adsorption Behaviour of Justicia Secunda Leaves Extract as an Eco‐Friendly Inhibitor for Aluminium in Acidic Media

2021 ◽  
Vol 11 (5) ◽  
pp. 13019-13030
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Weight Loss ◽  
Electrochemical Impedance ◽  
Physical Adsorption ◽  
Charge Transfer Resistance ◽  
Aluminum Surface ◽  
Protective Film ◽  
Transfer Resistance ◽  
Scanning Electron

The extract of Justicia secunda (JS) leaves was investigated as an eco‐friendly corrosion inhibitor of aluminum in 0.5 M HCl using weight loss, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and scanning electron microscopy (SEM) techniques. The inhibitor concentrations used ranged from 50 to 250 ppm at 30, 40, and 50oC. Results show that Justicia secunda acts as a good inhibitor for aluminum. Its efficiency increased with increasing inhibitor concentration but decreased with increasing temperature. Maximum inhibition efficiency as high as 94.3% was found at 30°C for 250 ppm of the inhibitor with the weight loss technique. Tafel polarization results show that the extract acts as a mixed-type inhibitor. The Nyquist plots indicated decreasing double-layer capacitance and increasing charge transfer resistance on increasing JS concentration. The inhibition action occurred through the physical adsorption of the extract on the aluminum surface. The adsorption process was found to follow Langmuir adsorption isotherm. The formation of a protective film on the metal surface was confirmed by scanning electron microscopy.

scholarly journals Analysis of the type material of Gomphosphenia tackei (Bacillariophyceae) and comparison to epizoic diatom populations on freshwater snails

2021 ◽  
Vol 154 (2) ◽  
pp. 257-263
Author(s):  
Mateusz Rybak ◽  
Łukasz Peszek ◽  
Anita Poradowska
Keyword(s):  
Electron Microscopy ◽  
Lymnaea Stagnalis ◽  
Morphological Characteristics ◽  
Small Cell ◽  
Type Material ◽  
Freshwater Snails ◽  
Sem Images ◽  
Small Cell Size ◽  
Type Population ◽  
Scanning Electron

Background and aims – Hustedt (1942) originally described Gomphosphenia tackei from Germany under the name Gomphonema tackei. Because of the small cell size and the lack of scanning electron microscopy (SEM) images from the type material, it is often confused with other species from this genus, especially with G. stoermeri. The aim of this paper was to present detailed morphological characteristics of G. tackei based on the analysis of the type material and of several epizoic populations from Central Europe. Material and methods – The material in this study was collected from the shells of the freshwater snails Lymnaea stagnalis, Planorbarius corneus, and Planorbis planorbis. Additionally, for an unambiguous species identification, the type material for Gomphosphenia tackei was analyzed using light and scanning electron microscopes.Key results – The presence of Gomphosphenia tackei was confirmed in the studied material. The largest population (up to 19%) was recorded on the shell surfaces of living snails, whereas on empty shells, the diatom did not seem to be present or only in very low numbers. Valves are typically clavate with rounded apices. Valves are frequently observed in girdle view, often joint together in pairs. The valves in the studied populations had a valve length of 7–29 µm, a valve width of 3–4 µm, and a stria density of 25–29 striae in 10 µm. In the type population, valve length ranged from 7.5 to 27 µm with a valve width of 3.0–4.0 µm and a stria density of 23–29 striae per 10 µm. Striae were composed of 2–4 elongated to rounded areolae per stria. At the apices, the striae were composed of one single areola. The cells were attached to the substratum by their footpole.Conclusion – Published illustrations of Gomphosphenia tackei do not always correctly represent this species. Individual cells are attached to the substratum by secreted mucilage, probably via their areolae or girdle band pores located on the footpole.

Fabrication of Ultra Thick Ferromagnetic Structures in Silicon

2004 ◽  
Author(s):  
Debbie G. Jones ◽  
Albert P. Pisano
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Scanning Electron Microscopy ◽  
Saturation Magnetization ◽  
Silicon Wafer ◽  
Fabrication Process ◽  
Sem Images ◽  
Deep Reactive Ion Etching ◽  
Scanning Electron

A novel fabrication process is presented to create ultra thick ferromagnetic structures in silicon. The structures are fabricated by electroforming NiFe into silicon templates patterned with deep reactive ion etching (DRIE). Thin films are deposited into photoresist molds for characterization of an electroplating cell. Results show that electroplated films with a saturation magnetization above 1.6 tesla and compositions of approximately 50/50 NiFe can be obtained through agitation of the electrolyte. Scanning electron microscopy (SEM) images show that NiFe structures embedded in a 500 μm thick silicon wafer are realized and the roughening of the mold sidewalls during the DRIE aids in adhesion of the NiFe to the silicon.

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