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Influence of Li2CO3 and ZnO Nanoparticle on Microstructure and Magnetic Properties of Low-Temperature Sintering LiZnTiBi Ferrites for High-Frequency Applications
Fang Xu,
Yulong Liao,
Huaiwu Zhang
Issue:
Volume 8, Issue 3, May 2019
Pages:
35-39
Received:
28 May 2019
Published:
29 July 2019
Abstract: LiZnTi ferrite ceramics with high saturation flux density (Bs), large remanence ratio (Br/Bs) and high saturation magnetization (4πMs) is a vital material for high frequency devices. In the present work, we prepared uniform and compact LiZnTiBi ferrite with large average grain size (>30μm) at 900°C. Firstly, the hybrid materials, including Li2CO3, ZnO, TiO2, Bi2O3 and Fe2O3, were pre-sintered at 850°C at O2 atmosphere. Next, composite additives composited of Li2CO3 and ZnO nanoparticles were added to control grain growth. The influences of the Li2CO3 and nano-ZnO (LZ) on the microstructure and magnetic properties of LiZnTiBi ferrite, especially for grain size, have been analyzed. SEM images demonstrated that moderate LZ additives (x=0.75 wt%) can prevent abnormal grains. Also, the ferrite samples possess compact microstructures. The phenomenon indicated that the LZ additive is a good sintering aid for low-temperature sintering LiZnTiBi ferrites. XRD patterns showed that all samples have a pure spinel phase. The magnetic properties, including Bs, Br/Bs and 4πMs, have weak change when LZ additives were added. However, due to smaller average grain size, the coercivity (Hc) gradually increased. Thus, a low-temperature sintering LiZnTiBi ferrite with high saturation flux density (Bs=311.10 mT), large remanence ratio (Br/Bs=0.86), low coercivity (Hc=244.6 A/m) and high saturation magnetization (Ms=75.40) was obtained when 1.00 wt% LZ additive was added. More important, the LiZnTiBi ferrite possessed uniform average grain. Such a sintering method (i.e., adding composite additive to control abnormal grain) should also promote synthesis of other advanced ceramics for practical applications.
Abstract: LiZnTi ferrite ceramics with high saturation flux density (Bs), large remanence ratio (Br/Bs) and high saturation magnetization (4πMs) is a vital material for high frequency devices. In the present work, we prepared uniform and compact LiZnTiBi ferrite with large average grain size (>30μm) at 900°C. Firstly, the hybrid materials, including Li2CO3, ...
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Inorganic Phosphate Effect of on Human Dental Pulp Cell Cultures
Jomana Alsenan,
Laisheng Chou
Issue:
Volume 8, Issue 3, May 2019
Pages:
40-46
Received:
1 July 2019
Accepted:
5 August 2019
Published:
23 August 2019
Abstract: This study was designed to investigate the effect of inorganic phosphate (Pi) at different concentrations on odontogenesis of the normal human dental pulp cells (hDPCs). Normal human dental pulp cells derived from extracted pristine teeth were cultured in growth medium with supplements of inorganic phosphate (Pi) in 0 ppm, 2 ppm, 4 ppm, 5 ppm and 8 ppm, for the time intervals of 16 hours, 7, 14, and 21 days. Cell proliferation rates were measured by the optical density of crystal violet dye stained cells. ALP activity was measured by fluorometric assay. Expression of Dentin Sialoprotein (DSP) was measured by ELISA. The data were presented as the mean of triplicates. Statistical analysis was conducted using JMP Pro 12 (ver. 12.1.0) in one-way ANOVA and Tukey HSD post-hoc tests. Cell attachment efficiency was reduced significantly by additional Pi of 2, 4 and 5 ppm (P<0.05). At 21 days, cultures with 2, 4 and 5 ppm supplemental Pi displayed significantly higher cell proliferation rates compared to the control group at day 14 (P<0.05) and at day 21 (P<0.05). At day 7, cultures with 2, 4, 5 and 8 ppm supplemental Pi yield significantly higher levels of ALP activity (P<0.05) compared to the control group. At day 7, cultures with 5 ppm Pi supplement showed significantly higher levels of DSP expression (P<0.05) compared to the control group and the rest of the other groups. Supplemental Pi in concentration of 5 ppm could significantly induce proliferation and odontogenesis of hDPCs. This is the first report to demonstrate Pi-induced odontogenesis, leading to potential development and clinical application of future Pi containing dental pulp capping or root canal filling materials.
Abstract: This study was designed to investigate the effect of inorganic phosphate (Pi) at different concentrations on odontogenesis of the normal human dental pulp cells (hDPCs). Normal human dental pulp cells derived from extracted pristine teeth were cultured in growth medium with supplements of inorganic phosphate (Pi) in 0 ppm, 2 ppm, 4 ppm, 5 ppm and 8...
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Microstructure and Strength of Titanium After Heat Treatment at Different Temperatures in the Range of 680-1000°C
Xingyu Zhang,
Benjamin Hanes,
Daniel Brooks,
Steve Niezgoda
Issue:
Volume 8, Issue 3, May 2019
Pages:
47-55
Received:
18 July 2019
Published:
27 August 2019
Abstract: The main purpose of this research is to determine the effect of brazing treatment on mechanical properties of both titanium Grade 2 and titanium Grade 5 alloys. The research group obtained Grade 2 and Grade 5 titanium alloys and brazing- treated them at temperatures of 680, 800, 850, 900, 920, 950, and 1000°C. Afterward, each sample was tensile tested, mounted, hardness tested, and observed by optical microscope to investigate corresponding microstructures. Based on the result sheets, it was revealed that the yield strength and tensile strength and ultimate strength of Ti Grade 2 alloys showed drastic fall after heating to 680°C, then no change up to 850°C, fall again up to 950°C, and remained unchanged strength to 1000°C However, the Ti Grade 5 samples showed completely different behavior. The yield strength was unchanged after heating to different temperatures. When heating to 680°C. It didn’t affect the strength at all, then after heating to 800°C, the strength decreased about 100MPa. But after this, higher temperatures didn’t change strength anymore. The Ultimate strength however showed a different trend as it continuously went down at elevated temperature. Meanwhile, the hardness of both alloys decreased constantly when temperature increased. Regarding Ti Grade 2 alloys, the initial drop in strength was due to annealing. Around 800°C, alpha laths started to form and that caused strength to increase. When the temperature reached at 850°C, the basketweave alpha laths were formed. Over that temperature, the grain sizes were significantly large which caused the strength to decrease. However, there was not much of change in alpha/beta ratio for Ti Grade 5 alloys. EBSD could be a helpful method since the alpha grain size can be determined from that.
Abstract: The main purpose of this research is to determine the effect of brazing treatment on mechanical properties of both titanium Grade 2 and titanium Grade 5 alloys. The research group obtained Grade 2 and Grade 5 titanium alloys and brazing- treated them at temperatures of 680, 800, 850, 900, 920, 950, and 1000°C. Afterward, each sample was tensile tes...
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