Strategies for Improving Effectively the Grade of a Siliceous-Calcareous Phosphate Ore

2013 ◽  
Vol 448-453 ◽  
pp. 3851-3854
Author(s):  
Fang Guo ◽  
Jun Li
Keyword(s):  
Chemical Composition ◽  
Chemical Industry ◽  
High Purity ◽  
Surface Characteristics ◽  
Sem Images ◽  
Size Fractions ◽  
Pairwise Combination ◽  
Phosphate Ore

High purity phosphatic chemicals should be produced for the development of phosphorus chemical industry. The effects of pairwise combination of scrubbing, calcination and flotation techniques on chemical composition content of different size fractions of a siliceous-calcareous phosphate ore are investigated. The grades of the different size fractions processed by flotation first and then by calcination are higher than those processed by scrubbing first and then by calcination. The grades of the coarse fractions are all higher than 30%, and it can be up to 35.43% for the 98~200 μm fraction. Moreover, the A.I. contents of the all fractions decrease obviously. Especially, it decreases from 11.12% to 5.14% for the fine < 74 μm fraction, which is lower than that processed by scrubbing first and then by calcination about 5%. The SEM images indicate that the effects of scrubbing and calcination on surface characteristics of ore samples are different.

In Situ Surface Biodegradation of Restorative Materials

2014 ◽  
Vol 39 (4) ◽  
pp. 349-360 ◽  
Author(s):  
GC Padovani ◽  
SBP Fúcio ◽  
GMB Ambrosano ◽  
MAC Sinhoreti ◽  
RM Puppin-Rontani
Keyword(s):  
Chemical Composition ◽  
Surface Characteristics ◽  
Sem Images ◽  
Dental Biofilm ◽  
Initial Chemical Composition ◽  
Restorative Materials ◽  
Dependent Parameter ◽  
Kolmogorov Smirnov ◽  
In Situ Biodegradation

SUMMARY This study aimed to evaluate the surface characteristics of restorative materials (roughness, hardness, chemical changes by energy-dispersive spectroscopy [EDX], and scanning electron microscopy [SEM]) submitted to in situ biodegradation. Fifteen discs of each material (IPS e.max [EM], Filtek Supreme [FS], Vitremer [VI], Ketac Molar Easymix [KM], and Amalgam GS-80 [AM]) were fabricated in a metallic mold (4.0 mm × 1.5 mm). Roughness, hardness, SEM, and EDX were then evaluated. Fifteen healthy volunteers used a palatal device containing one disc of each restorative material for seven days. After the biodegradation, the roughness, hardness, SEM, and EDX were once again evaluated. Data obtained from the roughness and hardness evaluations were submitted to Kolmogorov-Smirnov and Tukey-Kramer tests (p&lt;0.05). All esthetic restorative materials showed a significant increase in the roughness after biodegradation. Before biodegradation, significant differences in the hardness among the materials were seen: EM&gt;AM&gt;FS&gt;KM&gt;VI. After biodegradation, the hardness was significantly altered among the materials studied: EM&gt;AM&gt;FS=KM&gt;VI, along with a significant increase in the hardness for AM, KM, and VI. SEM images indicated degradation on the surface of all materials, showing porosities, cracks, and roughness. Furthermore, after biodegradation, FS showed the presence of Cl, K, and Ca on the surface, while F was not present on the VI and KM surfaces. EM and AM did not have alterations in their chemical composition after biodegradation. It was concluded that the dental biofilm accumulation in situ on different restorative materials is a material-dependent parameter. Overall, all materials changed after biodegradation: esthetic restorative materials showed increased roughness, confirmed by SEM, and the ionomer materials and silver amalgam showed a significantly higher hardness. Finally, the initial chemical composition of the composite resin and ionomer materials evaluated was significantly altered by the action of the biofilm in situ.

Effects of Etching on Zircon Grains and its Implications for the Fission Track Method

2012 ◽  
Vol 66 (5) ◽  
pp. 545-551 ◽  
Author(s):  
Carlos Alberto Tello Sáenz ◽  
Eduardo Augusto Campos Curvo ◽  
Airton Natanael Coelho Dias ◽  
Cleber José Soares ◽  
Carlos José Leopoldo Constantino ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Crystal Lattice ◽  
Fission Track ◽  
Surface Characteristics ◽  
Optical Microscope ◽  
Etching Time ◽  
X Ray ◽  
Track Method ◽  
Zircon Fission Track ◽  
Natural Zircon

Studies of zircon grains using optical microscopy, micro-Raman spectroscopy, and scanning electron microscopy (SEM) have been carried out to characterize the surface of natural zircon as a function of etching time. According to the surface characteristics observed using an optical microscope after etching, the zircon grains were classified as: (i) homogeneous; (ii) anomalous, and (iii) hybrid. Micro-Raman results showed that, as etching time increases, the crystal lattice is slightly altered for homogeneous grains, it is completely damaged for anomalous grains, and it is altered in some areas for hybrid grains. The SEM (energy dispersive X-ray spectroscopy, EDS) results indicated that, independent of the grain types, where the crystallinity remains after etching, the chemical composition of zircon is approximately 33% SiO2:65% ZrO2 (standard natural zircon), and for areas where the grain does not have a crystalline structure, there are variations of ZrO2 and, mainly, SiO2. In addition, it is possible to observe a uniform surface density of fission tracks in grain areas where the determined crystal lattice and chemical composition are those of zircon. Regarding hybrid grains, we discuss whether the areas slightly altered by the chemical etching can be analyzed by the fission track method (FTM) or not. Results of zircon fission track and U-Pb dating show that hybrid and homogeneous grains can be used for dating, and not only homogeneous grains. More than 50 sedimentary samples from the Bauru Basin (southeast Brazil) were analyzed and show that only a small amount of grains are homogeneous (10%), questioning the validity of the rest of the grains for thermo-chronological evolution studies using zircon FTM dating.

scholarly journals Effect of Bioconditioning on Surface Characteristics of Periodontally-affected Roots of Diabetic Patients

2014 ◽  
Vol 5 (2) ◽  
pp. 81-86
Author(s):  
Hossam A Eid ◽  
Khalid M Abdelaziz ◽  
Refaat A Eid
Keyword(s):  
Citric Acid ◽  
Chronic Periodontitis ◽  
Negative Impact ◽  
Surface Characteristics ◽  
Diabetic Patients ◽  
Type Ii ◽  
Sem Images ◽  
Root Surfaces ◽  
Tetracycline Hcl

ABSTRACT Objective Advanced glycosylated end products (AGEs) in type II diabetic patients are usually precipitated on the periodontallyaffected root surfaces. The presence of periodontopathic microbes, at the same time, may also add a negative impact on the prognosis of the regenerative periodontal surgery. This in vitro study aimed to evaluate the effect of chemical conditioning on surface characteristics of periodontally-affected roots of diabetic patients. Methods Three groups (n = 25) of freshly-extracted teeth were collected from the outpatient clinics, College of Dentistry, King Khalid University. In group 1, teeth were collected from healthy individuals for orthodontic purpose. Teeth of group 2 were collected from healthy patients with chronic periodontitis, while those of group 3 were collected from diabetic patients with chronic periodontitis. Roots of the collected teeth were examined using the scanning electron microscope (SEM) before and after mechanical surface planning and chemical treatment using normal saline, EDTA gel, Tetracycline HCL (TC) or citric acid (CA) each for 4 minutes (n = 5 from each group). Results Interpretation of SEM images revealed undesirable etching effect of the chemicals used on the surfaces of healthy roots. Although EDTA showed an effective cleanse of the smear debris, it seemed to have no power on surface cuticles existed on roots of diabetic individuals. Tetracycline HCl provided acceptable conditioning of periodontally-affected root surfaces. Citric acid showed a powerful removal of both smear debris and cuticle layers off the periodontally-affected roots of diabetic individuals. Conclusion Topical application of EDTA, TC or CA shows sensible effect on the periodontally affected root surfaces. However, each of these chemicals exhibits different conditioning power. Citric acid is a promising agent to biomodify the periodontally-affected root surfaces of diabetic patients. Clinical relevance Citric acid is an acceptable biomodifier for the periodontally-affected root surfaces. This approach may improve the prognosis of periodontal therapies especially in type II diabetic patients. How to cite this article Abdelaziz KM, Eid HA, Eid RA. Effect of Bioconditioning on Surface Characteristics of Periodontally- affected Roots of Diabetic Patients. World J Dent 2014;5(2):81-86.

Influence of the chemical composition and formulation of fluorinated epoxy resin on its surface characteristics

2019 ◽  
Vol 112 ◽  
pp. 452-460 ◽  
Author(s):  
Benoit Minisini ◽  
Sébastien Rolère ◽  
Jean-François Coulon ◽  
Fabienne Poncin-Epaillard
Keyword(s):  
Chemical Composition ◽  
Epoxy Resin ◽  
Surface Characteristics ◽  
Fluorinated Epoxy

Influence of Gypsum Additive on the Formation of Tobermorite in Autoclaved Aerated Concrete

2016 ◽  
Vol 714 ◽  
pp. 116-121 ◽  
Author(s):  
Ester Helanova ◽  
Rostislav Drochytka ◽  
Vit Cerný
Keyword(s):  
Chemical Composition ◽  
Hydrothermal Reaction ◽  
Raw Materials ◽  
Fly Ashes ◽  
Sem Images ◽  
X Ray ◽  
Autoclaved Aerated Concrete ◽  
Variable Chemical ◽  
Aerated Concrete

The quality of the aerated concrete strongly depends on the chemical composition of the raw materials, as well as the process of the hydrothermal reaction during autoclaving. Due to the variable chemical composition of fly ashes, it is necessary to identify the effect of each ion on the formation of the microstructure of aerated concrete. This paper examines the process of formation of tobermorite with the addition of sulphates in various percentage representation. The microstructure of aerated concrete is assessed using SEM images and the mineralogical by means of X-ray analysis.

Influence of lead dioxide electrodes morphology on kinetics and current efficiency of oxygen-ozone evolution reactions

2010 ◽  
Vol 64 (6) ◽  
Author(s):  
Élen Rufino ◽  
Mario Santana ◽  
Luiz Faria ◽  
Leonardo Silva
Keyword(s):  
Current Efficiency ◽  
Lead Dioxide ◽  
Water Discharge ◽  
Water Electrolysis ◽  
Surface Characteristics ◽  
Ozone Production ◽  
Sem Images ◽  
Pbo2 Electrode ◽  
Tafel Slopes ◽  
Experimental Findings

AbstractInfluence of electrode morphology on electrochemical properties of lead dioxide electrodes (β-PbO2) for oxygen-ozone evolution reactions in acid medium was investigated using scanning electronic microscopy (SEM), cyclic voltammetry (CV), polarization curves (PC), and determination of the current efficiency (Φ). Experimental findings revealed that application of high electrodeposition current densities furnishes more rough β-PbO2 films. Surface characteristics were verified by SEM images and the analysis of interfacial pseudo-capacitances and morphology factor (φ). Kinetic study of the overall electrode process (O2 + O3) based on the analysis of the Tafel slope revealed that the electrode morphology and electrolyte composition considerably affect the electrode kinetics. In most cases, the existence of two Tafel slopes distributed in the low and high overpotential domains was observed. Abnormal Tafel slopes (b ≠ 120 mV) obtained for the primary water discharge step during water electrolysis were interpreted considering the apparent charge transfer coefficient (α apa). Optimum conditions for the ozone production were obtained for the less rough β-PbO2 electrode immersed in a sulfuric acid solution (1.0 mol dm−3) containing KPF6 (30 × 10−3 mol dm−3), where the current efficiency of 15 mass % for the ozone production was obtained.

Hydrothermal Synthesis and Surface Characteristics of Novel Alpha Alumina Nanosheets with Controlled Chemical Composition

2010 ◽  
Vol 22 (24) ◽  
pp. 6564-6574 ◽  
Author(s):  
Wojciech L. Suchanek ◽  
Juan M. Garcés ◽  
Pasquale F. Fulvio ◽  
Mietek Jaroniec
Keyword(s):  
Hydrothermal Synthesis ◽  
Chemical Composition ◽  
Surface Characteristics ◽  
Alpha Alumina
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