Effects Of H2 Treatment Research Articles

Effect of H2 treatment under UV-B irradiation on the enrichment of germinated soybean isoflavones and mechanisms based on growth state, antioxidant system, and metabolomics

This study investigated the impact of hydrogen (H2) treatment under ultraviolet B (UV–B) irradiation on the growth status, antioxidant system, metabolite changes, and isoflavone content and composition of germinated soybeans. The results showed that compared with UV-B alone, H2 promoted the growth of germinated soybeans by regulating the content of metabolites (nucleotides, fats, amino acids, hormones, and neurotransmitters) and related metabolic pathways. H2 resists UV-B stress by binding directly to reactive oxygen species or mediating the antioxidant system. Increased activity and gene expression of phenylalanine ammonia-lyase, cinnamic acid-4-hydroxylase, and 4-coumaric acid coenzyme A ligase promoted isoflavone enrichment and promoting the conversion of glycosides to aglycones by reducing the activity and gene expression of isoflavone 7-O-glucosyltransferase and isoflavone 7-O-glucoside-6″-O-malonyltransferase. These results explain to some extent the possible reasons for the H2 treatment to alleviate UV-B stress, promote the growth of germinated soybeans, and enrich isoflavones (especially aglycones).

Effect of H2 treatment in barrier on interface, optical and electrical properties of InGaN light emitting diodes

Abstract The interface, optical and electrical properties of InGaN light emitting diodes (LEDs) with different H2 flow treatment during the barrier growth are investigated in this study. With H2 treatment, the interface between the quantum well and barrier becomes rougher and the photoluminescence intensity decreases. The external quantum efficiency of the LEDs with 600 sccm (2.7%) H2 treatment has the best performance among the samples. Both the forward and reverse leakage currents of the samples are reduced significantly when treated with H2. Among the samples, a H2 flow with 600 sccm (2.7%) gives the best performance.

The effect of H2 treatment at 423–573 K on the structure and synergistic activity of Pd–Cu alloy catalysts for low-temperature CO oxidation

The effect of H2 treatment at 423–573K on the structure of Cu/Pd/Al2O3 catalysts for low-temperature CO oxidation was studied by means of XRD, TEM, EDS, FFT, DRIFTS, and XPS methods. The formation of 5nm alloy particles in the Cu/Pd catalyst reduced at 423K was detected. The reaction on Cu/Pd, Pd, and Cu catalyst reduced at 423K starts at 275, 400, and 475K, respectively. The activation energy for CO oxidation on Cu/Pd, Pd, and Cu catalyst is 30, 90, and 110kJ/mol, respectively. The enhanced activity of Cu/Pd catalyst is explained by oxidation on Pd0–MOx interfaces (M=Pd, Cu). The key steps of this process are: oxidation of CO molecules strongly bound to Pd0 by lattice oxygen of MOx; fast desorption of CO2 molecules; replenishment of oxygen vacancies in MOx by oxygen molecules from reaction media. As a result, a substantial part of “blocked” Pd0 sites become available for adsorption and dissociation of O2 molecules. This is favorable for low-temperature oxidation via Langmuir–Hinshelwood mechanism. The increase in the reduction temperature results in a separation of alloy particles into metallic particles. As a result, Cu/Pd catalysts reduced at high temperatures are characterized with a decreased content of Pd0–MOx interfaces; an essential amount of “blocked” Pd0 sites and a decreased light-off activity.

Raman Scattering Study of Coalesced Single Walled Carbon Nanotubes

High temperature heat treatment of single wall carbon nanotube bundles in flowing H2 was used to produce a significant fraction (∼40%) of diameter-doubled, or coalesced tubes with a mean diameter corresponding to that of ∼(20, 20) tubes. At three laser excitation wavelengths (514.5, 647, and 1064 nm), a reduction in the Raman scattering intensity of the strong radial and tangential modes was observed in the H2-treated sample, consistent with the reduced fraction of tubes in the sample after coalescence. However, using 488 nm excitation, little or no change is observed in the Raman spectrum after the H2 treatment, suggesting that this excitation wavelength couples only to chiral symmetry tubes. Using the 647 nm excitation, the effect of H2 treatment on the tangential band is quite unique, and a significant change in the shape of the tangential band was observed. Our lineshape analysis, and other results reported in this issue, suggest that this unique change of shape is due to lost scattering intensity from metallic tubes partially compensated by tangential mode scattering from the coalesced tubes. The normally prominent radial breathing mode band, which would be expected at ∼90 cm−1 for ∼(20, 20) tubes was not observed, indicating that these larger diameter tubes do not exhibit strong resonant scattering, at least at any of the wavelengths used in this study.

Metal-Oxide Interaction in Alumina-Promoted Rh/SiO2 Catalyst. Effect of H2 Treatment on H2 Chemisorption and Cyclohexane Hydrogenolysis

Abstract An Al2O3-promoted Rh catalyst, containing Al2O3 deposited onto a Rh/SiO2 catalyst, exhibited an SMSI behavior: a significant suppression of both the H2 chemisorption capacity and the cyclohexane hydrogenolysis activity by high-temperature reduction and their recovery by O2 treatment at 673 K followed by low-temperature reduction.