scholarly journals Upper Pleistocene–Holocene in the continental slope of the Cará Basin: an integrated analysis based on planktic foraminifera, sedimentological and geochemical aspects

2021 ◽  
Vol 24 (3) ◽  
pp. 179-194
Author(s):  
Agathe Arrissa Noucoucouk ◽  
Robbyson Mendes Melo ◽  
George Satander Sá Freire ◽  
Eldemar de Albuquerque Menor
Keyword(s):  
Continental Slope ◽  
Cold Water ◽  
High Volume ◽  
Particle Size Analysis ◽  
Ocean Basin ◽  
Northeastern Brazil ◽  
Size Analysis ◽  
Integrated Analysis ◽  
Planktic Foraminifera ◽  
Upper Pleistocene

This research addresses paleoclimatic variations using sedimentological, geochemical, and planktic foraminifera. The study was carried out in a survey core (ANP 1011) collected on the continental slope of the Icaraí Sub-basin (Ceará Basin), on the coast of the Municipality of Itapipoca, CE, Brazil. Particle size analysis, CaCO3 content, Ti/Ca and Fe/Ca ratios, and the analysis of foraminifera associations for biostratigraphic purposes were performed. Based on the relative abundance of planktic foraminifera, with indicators of warm and cold water throughout the studied cores, two biozones (Y: Upper Pleistocene and Z: Holocene), and two subzones (Z2 and Z1) were recognized. The data of sedimentological markers obtained confirmed the occurrence of more wet phases in northeastern Brazil during the early stages of the Holocene. The Ti/Ca and Fe/Ca ratios, as well as the geochemical and micropaleontological proxies, indicated a farther north displacement of the Intertropical Convergence Zone (ITCZ) in the Pleistocene–Holocene transition. This may have caused greater precipitation in the Northeastern region of Brazil, effectuating the entry of a high volume of terrestrial sediments directly into the ocean basin. Keywords: Quaternary biostratigraphy, marine sedimentation, ITCZ mobility, paleoclimate.

Analysis of the Incorporation of Scheelite Residue in Kaolinitic Clay of Boa Saúde-RN

2012 ◽  
Vol 727-728 ◽  
pp. 844-849 ◽  
Author(s):  
Tércio G. Machado ◽  
Uilame Umbelino Gomes ◽  
Flanelson M. Monteiro ◽  
Samara M. Valcacer ◽  
Gilson G. da Silva
Keyword(s):  
Raw Materials ◽  
Particle Size Analysis ◽  
Northeastern Brazil ◽  
Size Analysis ◽  
Bending Tests ◽  
Materials Used ◽  
Kaolinitic Clay ◽  
The City ◽  
Mineral Waste

The scheelite occurs mainly in northeastern Brazil, with highest abundance in the states of Rio Grande do Norte and Paraíba - Scheelite Seridó Province. Mining is considered an activity that provides a high environmental degradation due to the large amount of minerals and waste involved. Most mining companies have no technologies or processes that allow the recycling of mineral waste generated. The aim of this study is to evaluate the influence of different percentages of reject on the mechanical properties of scheelite and aesthetic (staining of the final product after firing) of the clay of the city of Boa Saúde - RN. The raw materials used were characterized by XRD, XRF and particle size analysis. Assay was performed by water absorption, linear retraction and bending tests on three points for the characterization of the final product. The raw materials used were from the city of Currais Novos-RN.

Impact of Oil Additive Characteristics on Biofuel Engine Wear Using Electron Microscopy and Confocal Microscopy

2019 ◽  
Vol 798 ◽  
pp. 113-121
Author(s):  
Panyakorn Rungsritanapaisan ◽  
Preechar Karin ◽  
Dhritti Tanprayoon ◽  
Ruangdaj Tongsri ◽  
Katsunori Hanamura
Keyword(s):  
Diesel Engine ◽  
Research Study ◽  
Combustion Process ◽  
High Volume ◽  
Particle Size Analysis ◽  
Engine Oil ◽  
Size Analysis ◽  
Case Scenario ◽  
Worst Case ◽  
Engine Wear

Soot particles are produced during combustion process in the diesel engine. These particles will later exhaust into the thermosphere and part of them will contaminate the engine oil. When the lubricant is contaminated with soot, diesel engine abrasion or in a worst-case scenario lubricant starvation occurs. This situation will eventually lead into engine ware. High volume of soot also raises acid level of the area. If this state co-occurs with high temperature of the engine and volatile gases during operation, engine corrosion may also be produced. This research study the effect of additive volume on the dispersion of soot in engine oil and effect of additive on size and volume of soot which affect to mechanism of ware in metal by tribology four-ball tester, image analysis by scanning electron microscope and particle size analysis by laser diffraction technique.

scholarly journals Development and Characterization of Mg-SiC Nanocomposite Powders Synthesized by Mechanical Milling

2017 ◽  
Vol 742 ◽  
pp. 165-172 ◽  
Author(s):  
Daniela Penther ◽  
Claudia Fleck ◽  
Alireza Ghasemi ◽  
Ralf Riedel ◽  
Sepideh Kamrani
Keyword(s):  
Mechanical Milling ◽  
Volume Fraction ◽  
High Volume ◽  
Average Diameter ◽  
High Energy ◽  
Particle Size Analysis ◽  
Milling Process ◽  
Size Analysis ◽  
Magnesium Matrix ◽  
Nanocomposite Powders

Magnesium powder in micron scale and various volume fractions of SiC particles with an average diameter of 50 nm were co-milled by a high energy planetary ball mill for up to 25 h to produce Mg-SiC nanocomposite powders. The milled Mg-SiC nanocomposite powders were characterized by scanning electron microscopy (SEM) and laser particle size analysis (PSA) to study morphological evolutions. Furthermore, XRD, TEM, EDAX and SEM analyses were performed to investigate the microstructure of the magnesium matrix and distribution of SiC-reinforcement. It was shown that with addition of and increase in SiC nanoparticle content, finer particles with narrower size distribution are obtained after mechanical milling. The morphology of these particles also became more equiaxed at shorter milling times. The microstructural observation revealed that the milling process ensured uniform distribution of SiC nanoparticles in the magnesium matrix even with a high volume fraction, up to 10 vol%.

Acyclovir Loaded Solid Lipid Nanoparticle Based Cream: A Novel Drug Delivery System

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
EL- Assal I. A. ◽  
Retnowati .
Keyword(s):  
Drug Delivery ◽  
Drug Release ◽  
Antiviral Agent ◽  
Study Drug ◽  
Particle Size Analysis ◽  
Stability Study ◽  
Size Analysis ◽  
Solid Lipid ◽  
Dermal Delivery

Objective of the present investigation was enthused by the possibility to develop solid lipid nanoparticles (SLNs) of hydrophilic drug acyclovir. Also study vitro and vivo drug delivery. Methods: Drug loaded SLNs (ACV-SLNs) were prepared by high pressure homogenization of aqueous surfactant solutions containing the drug-loaded lipids in the melted or in the solid state with formula optimization study (Different lipid concentration, drug loaded, homogenization / stirring speed and compritol 888ATO: drug ratio). ACV - SLN incorporated in cream base. The pH was evaluated and rheological study. Drug release was evaluated and compared with simple cream- drug, ACV – SLN with compritol 888ATO and marketed cream. The potential of SLN as the carrier for dermal delivery was studied. Results: Particle size analysis of SLNs prove small, smooth, spherical shape particle ranged from 150 to 200 nm for unloaded and from 330 to 444 nm for ACV loaded particles. The EE% for optimal formula is 72% with suitable pH for skin application. Rheological behavior is shear thinning and thixotropic. Release study proved controlled drug release for SLNs especially in formula containing compritol88 ATO. Stability study emphasized an insignificant change in SLNs properties over 6 month. In-vivo study showed significantly higher accumulation of ACV in stratum corneum, dermal layer, and receptor compartment compared with blank skin. Conclusion: AVC-loaded SLNs might be beneficial in controlling drug release, stable and improving dermal delivery of antiviral agent(s).

APSAS; an Automated Particle Size Analysis System

Circular ◽  
1985 ◽  
Author(s):  
Lawrence J. Poppe ◽  
A.H. Eliason ◽  
J.J. Fredericks
Keyword(s):  
Particle Size ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Analysis System
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