scholarly journals Mineralogical Characterization of Manganese Oxide Minerals of the Devonian Xialei Manganese Deposit

Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1243
Author(s):  
Sida Niu ◽  
Liqun Zhao ◽  
Xiaoju Lin ◽  
Tong Chen ◽  
Yingchao Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Manganese Oxide ◽  
Spherical Particles ◽  
Manganese Ore ◽  
Manganese Deposit ◽  
Mineralogical Characterization ◽  
Mn Oxide ◽  
Oxide Minerals ◽  
Scanning Electron

The Guangxi Zhuang Autonomous Region is an important manganese ore district in Southwest China, with manganese ore resource reserves accounting for 23% of the total manganese ore resource reserves in China. The Xialei manganese deposit (Daxin County, Guangxi) is the first super-large manganese deposit discovered in China. The Mn oxide in the supergene oxidation zone of the Xialei deposit was characterized using scanning electron microscopy (SEM), energy spectrometer (EDS), transmission electron microscopy (TEM, HRTEM), and X-ray diffraction analysis (XRD). The Mn oxides have a gray-black/steel-gray color, a semi-metallic-earthy luster, and appear as oolitic, pisolitic, banded, massive, and cellular textures. Scanning electron microscopy images show that the manganese oxide minerals are present as fine-spherical particles with an earthy surface. TEM and HRTEM indicate the presence of oriented bundled and staggered nanorods, and nanopores between the crystals. The Mn oxide ore can be classified into two textural types: (1) oolitic and pisolitic (often with annuli) Mn oxide, and (2) massive Mn oxide. Pyrolusite, cryptomelane, and hollandite are the main Mn oxide minerals. The potassium contents of cryptomelane and pyrolusite are discussed. The unit cell parameters of pyrolusite are refined.

scholarly journals Deep Learning Based Instance Segmentation of Titanium Dioxide Particles in the Form of Agglomerates in Scanning Electron Microscopy

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 968
Author(s):  
Paul Monchot ◽  
Loïc Coquelin ◽  
Khaled Guerroudj ◽  
Nicolas Feltin ◽  
Alexandra Delvallée ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Titanium Dioxide ◽  
Learning Community ◽  
Spherical Particles ◽  
Average Value ◽  
Size Characterization ◽  
Scanning Electron

The size characterization of particles present in the form of agglomerates in images measured by scanning electron microscopy (SEM) requires a powerful image segmentation tool in order to properly define the boundaries of each particle. In this work, we propose to use an algorithm from the deep statistical learning community, the Mask-RCNN, coupled with transfer learning to overcome the problem of generalization of the commonly used image processing methods such as watershed or active contour. Indeed, the adjustment of the parameters of these algorithms is almost systematically necessary and slows down the automation of the processing chain. The Mask-RCNN is adapted here to the case study and we present results obtained on titanium dioxide samples (non-spherical particles) with a level of performance evaluated by different metrics such as the DICE coefficient, which reaches an average value of 0.95 on the test images.

scholarly journals Mineralogical characterization of clay mineral assemblages from Rio de Janeiro pegmatites to identify kaolinite and/or halloysite deposits

Cerâmica ◽  
2020 ◽  
Vol 66 (380) ◽  
pp. 483-495
Author(s):  
V. M. J. Salgado-Campos ◽  
L. C. Bertolino ◽  
F. J. da Silva ◽  
J. C. Mendes
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Chemical Analysis ◽  
Rio De Janeiro ◽  
Mineralogical Characterization ◽  
X Ray ◽  
Mineral Assemblages ◽  
Saprolite Zone ◽  
Scanning Electron

Abstract This study reports the mineralogical characterization of kaolin occurrences in the State of Rio de Janeiro, Brazil, to identify new kaolinite and halloysite deposits. Samples were collected in 10 pegmatites with varying sizes for X-ray diffractometry, chemical analysis by X-ray fluorescence, and scanning electron microscopy studies. The results indicated that the kaolin occurrences were of weathered origin, wherein some places there were occurrences of tubular halloysite. Concerning the regolith stratigraphy, samples located in the saprock zone were found to contain kaolinite and/or halloysite contents from 0 to 10.1%, while those located in the saprolite zone contained kaolinite and/or halloysite contents from 16.3% to 34.9%. Kaolinite and/or halloysite-7Å were formed from plagioclase weathering instead of K-feldspar or mica, and the halloysite-7Å occurrence was related to samples in regions with a higher degree of weathering.

scholarly journals DESIGN AND DEVELOPMENT OF RILPIVIRINE NANOPARTICLE CONTAINING CHITOSAN USING IONIC GELATION METHOD FOR HIV INFECTIONS

2020 ◽  
pp. 113-118
Author(s):  
MONTUKUMAR PATEL ◽  
NIRAV V. PATEL ◽  
TEJAS B. PATEL
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
In Vitro Release ◽  
Amorphous State ◽  
Hiv Infections ◽  
Spherical Particles ◽  
Ionic Gelation ◽  
Scanning Calorimetry ◽  
Scanning Electron

Objective: The primary objective of the current research was to prepare rilpivirine loaded Nanoparticles containing Chitosan using the ionic gelation method for HIV infections. Methods: The nanoparticles of rilpivirine were prepared using the ionic gelation technique. Further, nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and in vitro drug release. Results: The optimized nanoparticles were found with a particle size of 130.30±5.29 nm (mean±SD) and entrapment efficiency (% EE) of 77.10±0.50%. Scanning electron microscopy technique exposed spherical particles with uniform size. It was observed that the nanoparticles created showed the absence of the crystalline nature of the drug and its switch to the amorphous state. Results showed that more than 45% of the pure drug is released in 50 min and after 90 min almost about 95% of the drug is released. Conclusion: The research study concluded that the in vitro release profile of nanoparticles was found to be sustained up to 24 hr. Sustained release of the rilpivirine could improve patient obedience to drug regimens, growing action effectiveness. 

scholarly journals Reduction and Dissolution Behaviour of Manganese Slag in the Ferromanganese Process

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 97 ◽  
Author(s):  
Xiang Li ◽  
Kai Tang ◽  
Merete Tangstad
Keyword(s):  
Electron Microscopy ◽  
South Africa ◽  
Scanning Electron Microscopy ◽  
Liquidus Temperature ◽  
Reduction Rate ◽  
Manganese Ore ◽  
Thermo Gravimetric ◽  
Dissolution Behaviour ◽  
Manganese Slag ◽  
Scanning Electron

The reduction and liquidus behaviour of manganese slag with different basicities were studied in non-isothermal experiments in the temperature range of 1400–1500 °C. Certain amounts of quartz were added to Assmang ore (South Africa), and lime was added to Comilog ore (Gabon), to adjust the charge basicity to 0.5, 0.8 and 1.2. The extent of manganese ore reduction as a function temperature were determined by thermo-gravimetric (TG) balance. Morphology of ores and its change in the course of reduction was examined by scanning electron microscopy (SEM). The results show that the reduction rate of Assmang slag decreases with decreasing basicity, as the liquidus temperature of slag decreases. When spherical MnO phase is present, the activity of MnO is high, and the reduction rate is rapid. Comilog slags show a much higher reduction rate than Assmang slags. The activation energies of MnO reduction between 1400 to 1500 °C are estimated in this study and found to be 230 kJ/mol for Assmang charges and 470 kJ/mol for Comilog charges. The dissolution behaviours of Assmang and Comilog slags were also studied by FactSage simulation and verified by experiments.

Nanostructured CaWO4, CaWO4:Eu3+ and CaWO4:Tb3+ Particles: Sonochemical Synthesis and Luminescent Properties

2008 ◽  
Vol 8 (3) ◽  
pp. 1183-1190 ◽  
Author(s):  
Chunxia Li ◽  
Cuikun Lin ◽  
Xiaoming Liu ◽  
Jun Lin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Field Emission ◽  
Spherical Particles ◽  
X Ray Diffraction ◽  
Blue Emission Band ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Nanostructured CaWO4, CaWO4:Eu3+, and CaWO4:Tb3+ phosphor particles were synthesized via a facile sonochemical route. X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence, low voltage cathodoluminescence spectra, and photoluminescence lifetimes were used to characterize the as-obtained samples. The X-ray diffraction results indicate that the samples are well crystallized with the scheelite structure of CaWO4. The transmission electron microscopy and field emission scanning electron microscopy images illustrate that the powders consist of spherical particles with sizes from 120 to 160 nm, which are the aggregates of even smaller nanoparticles ranging from 10 to 20 nm. Under UV light or electron beam excitation, the CaWO4 powder exhibited a blue emission band with a maximum at 430 nm originating from the WO2−4 groups, while the CaWO4:Eu3+ powder showed red emission dominated by 613 nm ascribed to the 5D0 → 7F2 of Eu3+, and the CaWO4:Tb3+ powders showed emission at 544 nm, ascribed to the 5D4 → 7F5 transition of Tb3+. The PL excitation and emission spectra suggest that the energy is transferred from WO2−4 to Eu3+CaWO4:Eu3+ and to Tb3+ in CaWO4:Tb3+. Moreover, the energy transfer from WO2−4 to Tb3+ in CaWO4:Tb3+ is more efficient than that from WO2−4 to Eu3+ in CaWO4:Eu3+. This novel and efficient pathway could open new opportunities for further investigating the novel properties of tungstate materials.

Cuticular microstructures and their relationship to structural color and transpiration in the terrestrial isopod Porcellionides pruinosus

1985 ◽  
Vol 63 (3) ◽  
pp. 649-656 ◽  
Author(s):  
Neil F. Hadley ◽  
Gregory M. Hendricks
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Incident Light ◽  
Dorsal Surface ◽  
Surface Structures ◽  
Spherical Particles ◽  
Structural Color ◽  
Cuticular Transpiration ◽  
Terrestrial Isopod ◽  
Scanning Electron

The microstructure of the dorsal surface of the terrestrial isopod Porcellionides pruinosus was examined by scanning electron microscopy. Surface structures detected include sensory tricorns, spherical particles (balls) of various diameter, plates formed from the fusion of adjacent balls, and extremely small granules. A rod-shaped bacterium was also present on the surface of most individuals. The cuticular balls scatter and reflect incident light, producing a grayish white color or frosted appearance in most intermolt isopods. Prior to a molt, individuals are characteristically brown or unfrosted owing to the loss of the balls from the cuticle surface. New balls appear within a few hours following ecdysis and the isopod soon reacquires the frosted appearance. The balls are insoluble in lipid solvents and are also resistant to acetic acid and KOH. Higher water loss rates in unfrosted versus frosted individuals suggest that one function of the balls is to reduce cuticular transpiration in this species.

Synthesis, structure, and gas sensitivity properties of SnO2–CuO mixture phase obtained by pyrolysis of an aerosol

1997 ◽  
Vol 12 (2) ◽  
pp. 560-565
Author(s):  
J. Román ◽  
J. C. Fabian ◽  
M. Labeau ◽  
G. Delabouglise ◽  
M. Vallet-Regí
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Precursor Solution ◽  
Spherical Particles ◽  
Ultrahigh Frequency ◽  
Gas Sensitivity ◽  
Mixture Phase ◽  
Scanning Electron

SnO2–CuO mixture phase has been prepared by pyrolysis of an aerosol produced by ultrahigh frequency of different precursor solutions. As-received samples were annealed in different conditions to study the influence of the temperature on the microstructure. Scanning electron microscopy showed that the samples consisted of hollow spherical particles and rings, depending on the precursor solution utilized. The evolution of conductance under both pure and polluted air is discussed.

Low Molecular Weight Molecules of Oyster Nacre Induce Mineralization of the MC3T3-E1 Cells

2007 ◽  
Vol 361-363 ◽  
pp. 1017-1020
Author(s):  
Marthe Rousseau ◽  
Helene Boulzaguet ◽  
Julie Biagianti ◽  
Denis Duplat ◽  
Christian Milet ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Scanning Electron Microscopy ◽  
Extracellular Matrix ◽  
Raman Spectroscopy ◽  
Water Soluble ◽  
Spherical Particles ◽  
Signal Molecules ◽  
Low Molecular Weight ◽  
Scanning Electron

The nacre layer from the pearl oyster shell is considered as a promising osteoinductive biomaterial. Nacre contains one or more signal molecules capable of stimulating bone formation. The identity and the mode of action of these molecules on the osteoblast differentiation were analyzed. Water-soluble molecules from nacre were fractionated according to dialysis, solvent extraction and reversed-phase HPLC. The activity of a fraction composed of low molecular weight molecules in the mineralization of the MC3T3-E1 extracellular matrix was investigated. Mineralization of the preosteoblast cells was monitored according to alizarin red staining, Raman spectroscopy, scanning electron microscopy and quantitative RT-PCR. Molecules isolated from nacre, ranging from 50 to 235 Da, induced a red alizarin staining of the preosteoblasts extracellular matrix after 16 days of culture. Raman spectroscopy demonstrated the presence of hydroxyapatite in samples treated with these molecules. Scanning electron microscopy pictures showed at the surface of the treated cells the occurence of clusters of spherical particles ressembling to hydroxyapatite. The treatment of cells with nacre molecules accelerated expression of collagen I and increased the mRNA expression of Runx2 and osteopontin. This study indicated that the nacre molecules efficient in bone cell differentiation are certainly different from proteins, and could be useful for in vivo bone repair.

scholarly journals Fragmentable Heterogeneous Cocatalysts for the Metallocene-Catalyzed Polymerization of Olefins, I. Surface Modification of Silica and Characterization of the Resulting Carriers

2005 ◽  
Vol 60 (6) ◽  
pp. 603-613 ◽  
Author(s):  
Herbert Schumann ◽  
Ralf Widmaier ◽  
Katharina C. H. Lange ◽  
Birgit C. Wassermann
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Surface Modification ◽  
Nano Particles ◽  
Spherical Particles ◽  
Spherical Silica ◽  
Silica Materials ◽  
20 Nm ◽  
Scanning Electron

Surface modification of pre-dried spherical silica nano-particles with diameters of 235 nm and 10 to 20 nm and of commercially available non-spherical silica materials using various aminoalkyltrialkoxysilanes and α-ω-bis(alkoxysilyl)organyls (organyl = alkanediyl, aminoalkanediyl, polyether, polysiloxane) has been performed in suspension in solvents with water. The quantity of water has a dominating influence, as compared to the amounts and the ratios of silanes employed, on the surface morphology of the modified silicas. The morphologies observed range from weakly linked aggregates of spherical particles to large agglomerates covered by thick irregular layers of organopolysiloxane, as demonstrated by scanning electron microscopy. These carriers can be modified further with organoaluminium compounds to yield heterogeneous cocatalysts for the polymerization of ethylene.

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