Sierra Vista, AZ, United States
Sierra Vista, AZ, United States

Time filter

Source Type

Pei Y.,Yanshan University | Li Y.,Yanshan University | Che J.Y.,Desert Vista High School | Shen W.,Shanghai JiaoTong University | And 3 more authors.
International Journal of Hydrogen Energy | Year: 2015

To further improve the high-temperature electrochemical performance of perovskite-type oxides, the LaFeO3 carbon-coated composites used as the negative materials for MH-Ni batteries were obtained using the polyaniline (PANI) pyrolysis method. Transmission electron microscopy (TEM) results revealed that LaFeO3 particles were evenly coated with carbon layers, forming a core-shell structure. The carbon layers could enhance the conductivity and electrocatalytic activity, speeding up hydrogen protons transferring from electrolyte to electrode interface. Furthermore, the carbon coatings hindered the LaFeO3 particles from aggregating into stacks and reduced the corrosion of the LaFeO3 electrodes. At an elevated temperature (60°C), owing to the carbon coatings, the maximum discharge capacity of the LaFeO3 electrodes remarkably increased from 211mAhg-1 to 358mAhg-1, and charge retention (CR) increased from 85.4% to 94.6%. Also, the high rate dischargeability at a discharge current density of 1500mAg-1 (HRD 1500) increased from 21.0% to 37.6%, and the capacity retention rate after 100 cycles (S 100) increased from 63.0% to 70.9%. © 2015 Hydrogen Energy Publications, LLC.


Wang Y.,Yanshan University | Li Y.,Yanshan University | Shen W.,Yanshan University | Shen W.,Shanghai JiaoTong University | And 5 more authors.
Journal of Solid State Electrochemistry | Year: 2015

In order to improve the electrochemical kinetics of La–Mg–Ni-based alloy, the chemical modification of polypyrrole (PPy) doped with sodium sulfate (Na2SO4) has been applied on the surface of the La0.80 Mg0.20Ni2.70Mn0.10Co0.55Al0.10 alloy particles. SEM, TEM, and FT-IR results indicate that the spongy nano-PPy successfully forms on the surface of the alloy particles and that the PPy nanoparticles distribute uniformly. Owing to the nano-PPy, which possesses excellent electrochemical redox reversibility, electrocatalytic activity, and high conductivity, electrochemical kinetics of the alloy electrode is remarkably ameliorated. The high-rate dischargeability (HRD) of the treated alloy electrode at 1800 mA g−1 reaches two times of that for the bare alloy, meanwhile the discharge voltages increase obviously. The charge transfer resistance (Rct) of treated alloy electrode markedly decreases; the limiting current density (IL) and the hydrogen diffusion coefficient (D) increase. © 2015 Springer-Verlag Berlin Heidelberg


Pei Y.,Yanshan University | Li Y.,Yanshan University | Che J.Y.,Desert Vista High School | Shen W.,Yanshan University | And 4 more authors.
International Journal of Hydrogen Energy | Year: 2015

To further improve the high-temperature electrochemical performance of perovskite-type oxides, the LaFeO3 carbon-coated composites used as the negative materials for MH-Ni batteries were obtained using the polyaniline (PANI) pyrolysis method. Transmission electron microscopy (TEM) results revealed that LaFeO3 particles were evenly coated with carbon layers, forming a core-shell structure. The carbon layers could enhance the conductivity and electrocatalytic activity, speeding up hydrogen protons transferring from electrolyte to electrode interface. Furthermore, the carbon coatings hindered the LaFeO3 particles from aggregating into stacks and reduced the corrosion of the LaFeO3 electrodes. At an elevated temperature (60 °C), owing to the carbon coatings, the maximum discharge capacity of the LaFeO3 electrodes remarkably increased from 211 mAh g-1 to 358 mAh g-1, and charge retention (CR) increased from 85.4% to 94.6%. Also, the high rate dischargeability at a discharge current density of 1500 mA g-1 (HRD1500) increased from 21.0% to 37.6%, and the capacity retention rate after 100 cycles (S100) increased from 63.0% to 70.9%. Copyright © 2015 Hydrogen Energy Publications, LLC. All rights reserved.


Brent C.S.,Arid Land Agricultural Research Center | Miyasaki K.,Desert Vista High School | Vuong C.,Desert Vista High School | Miranda B.,Estrella Mountain Community College | And 3 more authors.
Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology | Year: 2016

Mating induces behavioral and physiological changes in the plant bug Lygus hesperus Knight (Hemiptera: Miridae). After receiving seminal products, which include the systemic regulator juvenile hormone (JH), females enter a post-mating period lasting several days during which they enhance their oviposition rate and lose interest in remating. To elucidate the regulation of these behavioral changes in L. hesperus, biogenic amines were quantified in the heads of females at 5 min, 1 h and 24 h after copulation and compared to levels in virgins using high-performance liquid chromatography coupled with electrochemical detection. Mating significantly increased dopamine (DA) after 1 and 24 h, and decreased octopamine (OA) after 5 min and 1 h. Serotonin did not change with mating, but tyramine was significantly reduced after 5 min. While injection of amines into virgin females did not influence sexual receptivity, OA caused a decrease in oviposition during the 24 h following injection. Topical application of the JH analog methoprene to virgins caused an increase in DA, and a decline in mating propensity, but did not influence other amines or the oviposition rate. The results suggest the decline in OA observed immediately after mating may promote egg laying, and that male-derived JH may induce an increase in DA that could account for the post-mating loss of sexual receptivity. © 2015, Springer-Verlag Berlin Heidelberg (outside the USA).


PubMed | Kristiansand Katedralskole Gimle, Desert Vista High School, Estrella Mountain Community College, Arid Land Agricultural Research Center and Arizona State University
Type: Journal Article | Journal: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology | Year: 2016

Mating induces behavioral and physiological changes in the plant bug Lygus hesperus Knight (Hemiptera: Miridae). After receiving seminal products, which include the systemic regulator juvenile hormone (JH), females enter a post-mating period lasting several days during which they enhance their oviposition rate and lose interest in remating. To elucidate the regulation of these behavioral changes in L. hesperus, biogenic amines were quantified in the heads of females at 5 min, 1 h and 24 h after copulation and compared to levels in virgins using high-performance liquid chromatography coupled with electrochemical detection. Mating significantly increased dopamine (DA) after 1 and 24 h, and decreased octopamine (OA) after 5 min and 1 h. Serotonin did not change with mating, but tyramine was significantly reduced after 5 min. While injection of amines into virgin females did not influence sexual receptivity, OA caused a decrease in oviposition during the 24 h following injection. Topical application of the JH analog methoprene to virgins caused an increase in DA, and a decline in mating propensity, but did not influence other amines or the oviposition rate. The results suggest the decline in OA observed immediately after mating may promote egg laying, and that male-derived JH may induce an increase in DA that could account for the post-mating loss of sexual receptivity.


Wang J.,Yanshan University | Han S.,Yanshan University | Li Y.,Yanshan University | Liu J.,Yanshan University | And 3 more authors.
Journal of Alloys and Compounds | Year: 2014

An investigation of the phase formation mechanism and electrochemical properties of the La0.75-xNdxMg0.25Ni 3.3 (x = 0, 0.15) alloys has been conducted in this paper. As explored by Rietveld analysis of the XRD data, the La0.75-xNd xMg0.25Ni3.3 alloy is composed of Ce2Ni7-type and Gd2Co7-type phases accompanied by minor CaCu5-type phase. The partial substitution Nd for La benefits the formation of Gd2Co 7-type phase, indicating that the atoms with smaller radius favor the formation of the Gd2Co7-type phase. However, CaCu5-type phase disappears with Nd substitution. Because part of the replaced La atoms transform into [A2B4] subunits with the Ni atoms, and the formed [A2B4] subunits crystallize with [AB5] subunits to produce A2B7-type phase, resulting in the depletion of the minor CaCu5-type phase. The electrochemical P-C isotherms present that the La0.75-xNdxMg0.25Ni 3.3 alloy only containing A2B7-type phase has one single plateau while the La0.75-xNdxMg0.25Ni3.3 alloy which contains minor LaNi5 phase has two plateaus. It is beneficial for the elevation of equilibrium plateau pressure ascribing to the contraction in cell volumes by Nd substitution. Electrochemical measurements show that the substitution of La by Nd improves the discharge capacity and the high rate dischargeability owing to the increase of A2B7-type phase abundance. © 2013 Elsevier B.V. All rights reserved.


Liu J.,Yanshan University | Han S.,Yanshan University | Li Y.,Yanshan University | Zhang J.,Yanshan University | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2013

La0.75Mg0.25Ni3.5 alloys with hexagonal (2H-) and rhombohedral (3R-) (La,Mg)2Ni7 phase were created by powder metallurgy. Partial crystal transformation of 2H- into 3R-type allotropes was realized by heat treatment and introducing LaNi5 compound. It was found that the alloy annealed within 1073-1223 K kept (La,Mg)2Ni7 phase and obvious crystal transformation of 2H- into 3R-type occurred as annealing temperature reached 1223 K. Electrochemical study showed similar discharge capacity and degradation behavior for La0.75Mg0.25Ni3.5 alloys with different amounts of 2H- and 3R-type allotropes while HRD was promoted by increasing 3R-type phase abundance. Introducing LaNi5 into La 0.75Mg0.25Ni3.5 alloy increased 3R- to 2H-type phase ratio and led to an additional plateau in P-C isotherms. LaNi5 introduction improved HRD, however it accelerated cycling degradation. Rietveld analysis indicated that after hydrogenation, the cell expansion of 2H- and 3R-type (La,Mg)2Ni7 phase was similar while the cell expansion of LaNi5 phase was smaller than that of (La,Mg) 2Ni7 phase. This caused discrete cell expansion between (La,Mg)2Ni7 and LaNi5 phases, leading to severe pulverization and oxidation. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Loading Desert Vista High School collaborators
Loading Desert Vista High School collaborators