scholarly journals Deposition of a SiO2 Shell of Variable Thickness and Chemical Composition to Carbonyl Iron: Synthesis and Microwave Measurements

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4624
Author(s):  
Arthur V. Dolmatov ◽  
Sergey S. Maklakov ◽  
Polina A. Zezyulina ◽  
Alexey V. Osipov ◽  
Dmitry A. Petrov ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Effective Medium Theory ◽  
Chemical Properties ◽  
Coaxial Line ◽  
Silica Layer ◽  
Medium Theory ◽  
Sio2 Shell ◽  
Two Factors ◽  
Magnetic Biosensor ◽  
Hydrolysis Of

Protective SiO2 coating deposited to iron microparticles is highly demanded both for the chemical and magnetic performance of the latter. Hydrolysis of tetraethoxysilane is the crucial method for SiO2 deposition from a solution. The capabilities of this technique have not been thoroughly studied yet. Here, two factors were tested to affect the chemical composition and the thickness of the SiO2 shell. It was found that an increase in the hydrolysis reaction time thickened the SiO2 shell from 100 to 200 nm. Moreover, a decrease in the acidity of the reaction mixture not only thickened the shell but also varied the chemical composition from SiO3.0 to SiO8.6. The thickness and composition of the dielectric layer were studied by scanning electron microscopy and energy-dispersive X-ray analysis. Microwave permeability and permittivity of the SiO2-coated iron particles mixed with a paraffin wax matrix were measured by the coaxial line technique. An increase in thickness of the silica layer decreased the real quasi-static permittivity. The changes observed were shown to agree with the Maxwell Garnett effective medium theory. The new method developed to fine-tune the chemical properties of the protective SiO2 shell may be helpful for new magnetic biosensor designs as it allows for biocompatibility adjustment.

scholarly journals PENGARUH KONSENTRASI LARUTAN KAPUR (Ca(OH)2) DAN LAMA PEREBUSAN TERHADAP MUTU TORTILLA JAGUNG

2017 ◽  
Vol 6 (2) ◽  
pp. 33-38
Author(s):  
Vita Novalina Lawalata ◽  
Tanudin Tanudin ◽  
Cynthia G C Lopulalan
Keyword(s):  
Chemical Composition ◽  
Chemical Properties ◽  
Single Factor ◽  
Factorial Experimental Design ◽  
Organoleptic Properties ◽  
Main Effect ◽  
Lime Solution ◽  
Two Factors ◽  
Carbohydrate Contents

The objective of this study was to analyze the effects of the concentration of caustic lime solution and boiling time on the quality of tortilla corn chips made from mature corn. A completely randomized factorial experimental design was applied in this study. Two factors were assigned including concentration of caustic lime solution (3, 4, and 5%) and boiling time (30, 60, and 90 minutes). Observed variables were both chemical properties (moisture, ash, protein, fat, and carbohydrate). Results showed that the interaction between concentration of caustic lime solution and boiling time did not have significant effect on protein and fat content of the tortilla. The main effect of a single factor boiling time mostly influenced many observed variables particularly the organoleptic properties of the tortilla. The concentration of caustic lime solution of 4% and boiling the corn for 30 minutes was the best interaction to produce tortilla having the best quality with moisture, ash, and carbohydrate contents of 5.53%, 7.59%, and 67.96%, respectively.   Keywords: corn, tortillas, lime, boiling, chemical composition, organoleptic    ABSTRAK Tujuan penelitian ini adalah untuk menganalisa pengaruh konsentrasi larutan kapur dan lama perebusan terhadap mutu tortilla jagung dari pemanfaatan jagung tua. Rancangan yang digunakan adalah Rancangan Acak Lengkap Faktorial dengan faktor konsentrasi larutan kapur (3%, 4%, dan 5%) dan faktor lama perebusan (30 menit, 60 menit, dan 90 menit). Peubah yang diamati adalah sifat kimia (kadar air, kadar abu, protein, lemak dan karbohidrat by different). Hasil penelitian menunujukan bahwa pengaruh larutan kapur dan lama perebusan menghasilkan kandungan protein dan lemak tidak nyata dalam interaksinya. Perlakuan dengan lama perebusan tortilla jagung lebih mempengaruhi peubah-peubah yang diamati terutama pada uji organoleptik rasa tortilla jagung. Interaksi terbaik pada konsentrasi larutan kapur 4% dan lama perebusan 30 menit, menghasilkan mutu tortilla jagung dengan kadar air 5,53%, kadar abu 7,59% dan kadar karbohidrat by different 67,96%. Kata kunci: jagung, tortilla, kapur, perebusan, komposisi kimia, organoleptik

The Effect of the Surface Layer on the Dielectric Constant of (Pb, La)TiO3 Thin Films

2002 ◽  
Vol 751 ◽  
Author(s):  
G.L. Yu ◽  
D.Q. Xiao ◽  
L.L. Meng ◽  
P. Yu ◽  
J.G. Zhu
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Numerical Modeling ◽  
Surface Layer ◽  
Chemical Composition ◽  
Effective Medium Theory ◽  
Ferroelectric Thin Films ◽  
Bulk Region ◽  
Medium Theory ◽  
Pyroelectric Detectors

ABSTRACT:(Pb, La)TiO3 (PLT) ferroelectric thin films are one of the promising candidates for applications in dynamic random memory and pyroelectric detectors, etc. However, the chemical composition in the surface layer of thin films is usually different from that in the “bulk” region of the thin films. For instance, it has been reported that there is Pb, Ti, or La enrichment in the surface layer of the (Pb, La)TiO3 thin films. According to a numerical modeling using effective-medium theory, which was developed in our group, we discussed the effect of the surface layer on the dielectric constant of (Pb, La)TiO3 thin films. The effect of Pb, Ti, or La enrichment in the surface layer on the dielectric constant of PLT thin films was discussed. And a case of the “upgraded” and the “down-graded” thin films was expatiated and discussed.

Chemical Composition of Ice Containing Tephra Layers in the Byrd Station Ice Core, Antarctica

1988 ◽  
Vol 30 (3) ◽  
pp. 315-330 ◽  
Author(s):  
Julie M. Palais ◽  
Philip R. Kyle
Keyword(s):  
Chemical Composition ◽  
Silicate Glass ◽  
Residence Time ◽  
Volcanic Ash ◽  
Global Climate ◽  
Ice Core ◽  
Volcanic Eruptions ◽  
Tephra Layers ◽  
The Antarctic ◽  
Hydrolysis Of

The chemical composition of ice containing tephra (volcanic ash) layers in 22 sections of the Byrd Station ice core was examined to determine if the volcanic eruptions affected the chemical composition of the atmosphere and precipitation in the vicinity of Byrd Station. The liquid conductivity, acidity, sulfate, nitrate, aluminum, and sodium concentrations of ice samples deposited before, during, and after the deposition of the tephra layers were analyzed. Ice samples that contain tephra layers have, on average, about two times more sulfate and three to four times more aluminum than nonvolcanic ice samples. The acidity of ice samples associated with tephra layers is lowered by hydrolysis of silicate glass and minerals. Average nitrate, sodium, and conductivity are the same in all samples. Because much of the sulfur and chlorine originally associated with these eruptions may have been scavenged by ash particles, the atmospheric residence time of these volatiles would have been minimized. Therefore the eruptions probably had only a small effect on the composition of the Antarctic atmosphere and a negligible effect on local or global climate.

Effective medium theory and the attenuation of graphite fiber composites

1993 ◽  
Vol 73 (7) ◽  
pp. 3441-3445 ◽  
Author(s):  
Herbert Überall ◽  
Barbara F. Howell ◽  
Earl L. Diamond
Keyword(s):  
Effective Medium Theory ◽  
Fiber Composites ◽  
Effective Medium ◽  
Graphite Fiber ◽  
Medium Theory
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