Papers by Keyword: Hydrogen Storage Alloy

Abstract: The mechanism of cancer cell death induced by hydrogen discharged from Pd-5at.% Ni hydrogen storage alloy has been investigated. Cancer cell (HeLa : cervical cancer cell) death was observed in the limited region within ~ 3 mm from the sample. The measurement of surviving fraction of cells revealed that almost all the cancer cells in the well of 96-well multi plate, 6.2 mm in diameter were extinct (p < 0.01), while no detectable influence was observed in the normal cells. From the fluorescent imaging experiment, it was indicated that the cell death induced by discharged hydrogen was due to the “Apoptosis” and hydrogen peroxide was detected in both intracellular and extracellular regions. Furthermore, the generation of hydrogen radical and hydroxyl radical was observed in the ESR measurement. From the results obtained, the mechanism of cancer cell death is proposed.

Abstract: A selective cancer cell death induced by discharged hydrogen from Pd-Ni base hydrogen storage alloy (HSA) powder is demonstrated. From the cell experiment and the measurement of surviving cell rate, it was found that cell death was seen only in cancer cells (HeLa : cervical cancer cell) after 24h- and 48h-immersion of Pd-5at.%Ni alloy powder, while no harmful influence was observed in normal cells (MDCK : renal epithelial cell). The range of cancer cell death was limited just near the HSA powder. It is suggested that the hydrogen radical emitted from the HSA powder induces the formation of hydrogen peroxide and brings a detrimental effect in the cancer cell, while hydrogen peroxide is decomposed by the enzyme, catalase, in normal cells, resulting in the selective death of cancer cells.

Abstract: X-ray diffraction results indicate that pristine alloy has a single LaNi5 phase and the alloys containing Fe0.43B0.57 consist of the matrix LaNi5 phase and the La3Ni13B2 secondary phase. The abundance of La3Ni13B2 phase increases with increasing x value. Maximum discharge capacity of the alloy electrodes monotonically decreases from 336.1 mAh/g (x = 0) to 281.2 mAh/g (x = 0.4). High-rate dischargeability of the alloy electrodes first increases with increasing x from 0 to 0.20, and then decreases when x increases to 0.4. Cycling stability decreases with increasing x from 0 to 0.4.

Abstract: With lanthanum, magnesium and nickel chloride as the main salt, citric acid (C₃H₈O₇•H₂O) as a complexing agent, La-Mg-Ni storage materials were prepared by galvanostatic electrodeposition method in aqueous solution. The effect of additive C₆H₄SO₂NNaCO•2H₂O on the properties of electrodeposited alloy film was studied. The results showed that: adding appropriate amount of C₆H₄SO₂NNaCO•2H₂O may be effective in improving the surface morphology of the La-Mg-Ni alloy film, and be more conducive to the formation of LaMg₂Ni₉ alloy phase; when the dosage was 0.20g/L, the cathodic polarization of the bath was the strongest, and cracks and pores were the least on the alloy film surface prepared by electro-deposited, the apparent activation free energy of alloy film was 48.2 kJ/mol, electrode absorption level Q was 0.030μF/cm², the alloy film resistor Rd was 138.5Ω/cm².

Abstract: The microstructure and electrochemical properties of a La_0.7Mg_0.3Al_0.3Mn₀.₄Co₀.₅Ni_3.8 hydrogen storage alloy have been studied. The anode was prepared using a mixture of the ingot alloy in the as-cast state with carbon black and polytetrafluoroethylene (PTFE) as a binder. A Ni (OH)₂ electrode was used as the cathode of the square-type test cell. A separator was used together with a 6M KOH electrolyte. Microstructure and phase composition of the alloy have been investigated using inductively coupled plasma atomic emission spectrometry (ICP-AES), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction analysis (XRD). A niobium-containing alloy has also been included for a comparison.

Abstract: Microstructure and self-discharge characteristics of Ti-Zr-V-Cr-Ni-Ce hydrogen storage electrode have been investigated by XRD, FESEM-EDS and EIS measurements. Self-discharge properties indicate that the irreversible capacity loss is negative, which is different from that of AB₅ alloy electrode. The capacity loss can be divided in two parts, one is due to the deterioration of the hydrogen storage alloy, which will result in the decrease of discharge capacity, and the other is due to the continually activated, which will result in the increase of discharge capacity.

Abstract: Microstructure and electrode characteristics of Ti-V-Cu-Cr-Ni metal hydride electrode alloy have been investigated by XRD, FESEM-EDS and EIS measurements. The result shows that the alloy is mainly composed of V-based solid solution phase with body-centered-cubic structure and TiNi-based secondary phase. The discharge capacity increases with increasing temperature in a wider temperature region from 303 K to 343 K. The result of electrochemical impedance spectrometry indicates that the charge transfer resistance decreases with increasing temperature, while the exchange current density in the bulk of the alloy increase with increasing temperature.

Abstract: Microstructure and electrochemical characteristics of La0.35Ce0.65Ni3.8-xCo0.8MnxAl0.4 alloys have been investigated. X-ray diffraction results indicate that the alloys consist of a single phase with CaCu5-type structure, and the lattice parameters a, c and cell volume V increase with increasing x value. The maximum discharge capacity of the alloy electrodes first increases from 217.9 (x = 0) to 290.1 mAh/g (x = 0.3), and then decreases to 271.3 mAh/g (x = 0.5). The high-rate dischargeability at the discharge current density of 1200 mA/g first increases from 58.4% (x = 0) to 78.2% (x = 0.3), and then decreases to 75.2% (x = 0.5). Both the charge-transfer reaction at the electrode/electrolyte interface and the hydrogen diffusion in the bulky alloys are responsible for the high-rate dischargeability. Cycling stability first increases with increasing x from 0 to 0.3 and then decreases when x increases to 0.5.

Abstract: The influence of discharged hydrogen from Pd-Ni based hydrogen storage alloys (HSAs) on cultured cells has been investigated. The susceptibility of cells to discharged hydrogen varied with the kind of cells. No influence was seen in the normal cells, while an effect of killing cancer cells was observed near the HAS and the region where the cell death was observed was limited to an extent of a few mm from the alloy surface. In order to examine the cause of the effects, the amount of gaseous hydrogen and hydrogen radicals released from the alloy surface and pH change of physiological saline aq. solution were measured. The amount of gaseous hydrogen and hydrogen radicals increased with time. The pH of physiological saline aq. solution decreased first and then recovered to the starting value after about 50h. The pH change behavior varied with alloy composition. It is inferred that the hydrogen radicals formed on alloy surface may bring a characteristic change in the cancer cells, leading to the effect of discharged hydrogen on cancer cell death.

Abstract: Amorphous MgNi+x%B(x=0,2,5,10) hydrogen storage alloys have been prepared by mechanical alloying (MA) and tested as hydrogen storage electrodes. The addition of boron can promote the MgNi alloy to form amorphous phase, increase the atom ratio of Ni/Mg at the alloy powders’ surface, and improve the thermal stability of MgNi alloy. The discharge capacity, the high rate dischargeability (HRD) and the exchange current density of the alloy electrodes all increased first, and then decreased with increasing the addition of boron. The maximum discharge capacity, the HRD400 and the exchange current density of the alloy with 5%B were 411.6mAh/g, 58.3% and 293.5mA/g respectively, which were 21.8%, 40.0% and 351.5% higher respectively, comparing with that of no boron addition. The electrochemical cycle stability of the alloy electrodes increased with increasing boron additions, and compared with no boron addition, the cycle capacity retention rate S₂₀ of the alloy with 10%B increased 64.2%.