H2 Treatment Research Articles

Engineering graphene properties by modulated plasma treatments

We demonstrate modulated H2 and O2 plasma treatments as an effective methodology for controlled chemical functionalization by hydrogen and oxygen atoms of single- and multi-layer chemical vapor deposition (CVD) graphene aiming at engineering material properties. The effects of the functionalization degree on the optical and transport properties of graphene are discussed with a twofold aim of (i) providing reproducible experimental protocols for tailoring graphene properties, and of (ii) providing insights into the chemical mechanisms involved in the plasma-processing of graphene with hydrogen and oxygen atoms.An unprecedented control over the graphene functionalization by hydrogen atoms is demonstrated together with the fine tuning of multi-layer graphene resistivity as well as the transition from metallic to semiconducting behavior with a gap opening. The interaction of oxygen atoms with multilayer graphene provides a strong modification of surface wettability without significant change in conductivity, thus suggesting that oxidation effects are mainly confined on the outmost graphene. Moreover, the air exposure of graphene oxidized by plasma treatment results in peculiar chemical mechanisms with important effect on the transport properties of the material. Finally, we investigate the restoration of graphene from graphene oxide by modulated hydrogen plasma.

Hydrogen can alleviate post-cardiac arrest myocardium injury in rabbits

To investigate the effects of hydrogen (H2) on myocardium injury post-cardiac arrest (CA) in rabbits. Sixty New Zealand rabbits were randomly divided into H2 treatment group (n = 30) and control group (n = 30) by random number table. The rabbit CA model was established by means of electrical stimulation of external membrane, both groups were mechanically ventilated. Cardiopulmonary resuscitation (CPR) was performed after 6 minutes of nonintervention, and stopped after restoration of spontaneous circulation (ROSC). Inhalation of 2% H2 gas was conferred to rabbits immediately at the end of CA modeling for 72 hours in H2 treatment group. Air was given to rabbits in control group instead. The survival rate of rabbits was analyzed. Heart rate, ventricular premature beat frequency, and the levels of blood samples cardiac troponin I (cTnI), left ventricular ejection fraction (LVEF), B-type natriuretic peptide (BNP), and blood lactic acid (Lac) were collected before CA and after ROSC in all rabbits. Rabbits were sacrificed and microstructure injury was observed by electric microscope after ROSC 72 hours. There were 28 animals ROSC in both groups; the survival number in H2 treatment group was higher than that in control group at 72 hours after ROSC (number: 15 vs. 7, χ2 = 4.791, P = 0.029). In the early stage of ROSC, the heart rate of two groups slowed down, the number of premature ventricular increased, and then gradually recovered; the heart rate in H2 treatment group was returning to normal more quickly than that in control group at 48 hours after ROSC (bpm: 319±63 vs. 362±40, P < 0.05); the ventricular premature beat frequency was lower than that in control group at 72 hours after ROSC (times per minutes: 9.1±4.3 vs. 15.0±8.0, P < 0.05). The animals of two groups had different degrees of myocardial damage and cardiac insufficiency after ROSC, and restored with the extension of time. Compared with control group, the level of BNP in H2 treatment group was significant decreased at 24 hours after ROSC (ng/L: 385±98 vs. 488±174, P < 0.05), the levels of cTnI and Lac were significant decreased at 48 hours after ROSC [cTnI (μg/L: 1.83±0.68 vs. 2.83±0.98, Lac (mmol/L): 5.5±1.6 vs. 7.9±2.6, both P < 0.01], the LVEF was slightly higher than that at 72 hours after ROSC (0.690±0.040 vs. 0.650±0.041, P = 0.051). Compared with control group, less damage to myocardial ultra structure was found in H2 treatment group at 72 hours after ROSC. Inhalation of H2 alleviates cardiac dysfunction and myocardial injury after CPR.

(Invited) TiO2 Nanotubes in Photocatalysis

TiO2 nanotubes in photocatalysis Ning Liu, Anca Mazare, Patrik Schmuki Department of Materials Science WW-4, LKO, University of Erlangen-Nuremberg, Martensstrasse 7, 91058 Erlangen, Germany In the past decade, anodically formed self-organized TiO2 nanotube layers attracted considerable scientific interest (see e.g. reviews [1,2]). This is mainly due to the fact that these layers combine the defined nanotubular geometry with a broad range of functional features inherent to TiO2. Particularly in photoelectrochemical and photocatalytic applications nanotubular layers have shown remarkable results. The presentation will first give an overview of the most promising features of classic nanotube layers for photocatalysis and then focus on TiO2 nanotube (NT) arrays, converted by a high pressure H2 treatment to anatase-like "black titania"[3,4]. This modification shows a remarkable high open-circuit photocatalytic hydrogen production rate without the presence of any cocatalyst. We will discuss the main effects caused by the high H2pressure annealing and the origin of this outstanding activity of black titania. REFERENCES P. Roy, S. Berger, P. Schmuki, Angew. Chem. Int. Ed. (2011), 2904K. Lee, A. Mazare, P. Schmuki, CHEMICAL REVIEWS, 114 (2014) 9385N. Liu, P. Schmuki et.al. Nano Letters, 14 (2014) 3309N. Liu, P. Schmuki et.al. 53 (2014) 14201

Molecular hydrogen inhalation attenuates postoperative cognitive impairment in rats

Postoperative cognitive decline is a major clinical problem with high morbidity and mortality after surgery. Many studies have found that molecular hydrogen (H2) has significant neuroprotection against acute and chronic neurological injury by regulating inflammation and apoptosis. In this study, we hypothesized that H2 treatment could ameliorate the development of cognitive impairment following surgery. Adult male rats were subjected to stabilized tibial fracture operation under anesthesia. Two percent of H2 was inhaled for 3 h beginning at 1 h after surgery. Separate cohorts of rats were tested for cognitive function with fear conditioning and the Y-maze test, or euthanized to assess blood-brain barrier integrity, and systemic and hippocampal proinflammatory cytokine and caspase-3 activity. Surgery-challenged animals showed significant cognitive impairment evidenced by a decreased percentage of freezing time and an increased number of learning trials on days 1, 3, and 7 after operation, which were significantly improved by H2 treatment. Furthermore, H2 treatment significantly ameliorated the increase in serum and hippocampal proinflammatory cytokines tumor necrosis factor-α, interleukin-1β, interleukin-6, and high-mobility group protein 1 in surgery-challenged animals. Moreover, H2 treatment markedly improved blood-brain barrier integrity and reduced caspase-3 activity in the hippocampus of surgery-challenged animals. These findings suggest that H2 treatment could significantly mitigate surgery-induced cognitive impairment by regulating inflammation and apoptosis.

Experimental and Theoretical Insights into Influence of Hydrogen and Nitrogen Plasma on the Water Splitting Performance of ALD Grown TiO2 Thin Films

Specific effects of hydrogen and nitrogen plasma treatment on anatase TiO2 photoanodes, grown via atomic layer deposition (ALD), and their respective impact on water splitting properties are reported. ALD grown TiO2 samples were exposed to reactive hydrogen and nitrogen plasmas and the photoelectrochemical efficiency of the modified samples were comparatively analyzed. Both H2 and N2 plasma treatment enhanced the photocurrent values compared to pristine TiO2. Electron density at oxygen vacancy sites was decreased upon nitrogen incorporation, reflected in band gap modulation and decreased recombination probability as confirmed by spectral data. Surface modification via H2 plasma induce more midgap states to augment the photoinduced charge carriers concentration that was supported by theoretical investigation performed on the electronic properties of both H- and N-doped TiO2 (anatase). First-principles calculations based on Hartree–Fock–Density Functional Theory (HF–DFT) hybrid models showed good agreement ...

Hydrogen Gas Inhalation Treatment in Acute Cerebral Infarction: A Randomized Controlled Clinical Study on Safety and Neuroprotection

Molecular hydrogen (H2) acts as a therapeutic antioxidant. Inhalation of H2 gas (1-4%) was effective for the improvement of cerebral infarction in multiple animal experiments. Thus, for actual applications, a randomized controlled clinical study is desired to evaluate the effects of inhalation of H2 gas. Here, we evaluate the H2 treatment on acute cerebral infarction. Through this randomized controlled clinical study, we assessed the safety and effectiveness of H2 treatment in patients with cerebral infarction in an acute stage with mild- to moderate-severity National Institute of Health Stroke Scale (NIHSS) scores (NIHSS = 2-6). We enrolled 50 patients (25 each in the H2 group and the control group) with a therapeutic time window of 6 to 24 hours. The H2 group inhaled 3% H2 gas (1 hour twice a day), and the control group received conventional intravenous medications for the initial 7 days. The evaluations included daily vital signs, NIHSS scores, physical therapy indices, weekly blood chemistry, and brain magnetic resonance imaging (MRI) scans over the 2-week study period. The H2 group showed no significant adverse effects with improvements in oxygen saturation. The following significant effects were found: the relative signal intensity of MRI, which indicated the severity of the infarction site, NIHSS scores for clinically quantifying stroke severity, and physical therapy evaluation, as judged by the Barthel Index. H2 treatment was safe and effective in patients with acute cerebral infarction. These results suggested a potential for widespread and general application of H2 gas.

Molecular hydrogen affects body composition, metabolic profiles, and mitochondrial function in middle-aged overweight women.

Molecular hydrogen (H2) effectively treats obesity-related disorders in animal models, yet no studies have investigated the effectiveness and safety of H2 for improving biomarkers of obesity in humans. In this double blind, placebo-controlled, crossover pilot trial, we evaluated the effects of H2 intervention on body composition, hormonal status, and mitochondrial function in ten (n=10) middle-aged overweight women. Volunteers received either hydrogen-generating minerals (supplying ~6ppm of H2 per day) or placebo by oral administration of caplets for 4weeks. The primary end-point of treatment efficacy was the change in the body fat percentage from baseline to 4weeks. In addition, assessment of other body composition indices, screening laboratory studies, and evaluation of side effects were performed before and at follow-up. Clinical trial registration www.clinicaltrials.gov , ID number NCT02832219. No significant differences were observed between treatment groups for changes in weight, body mass index, and body circumferences at 4-week follow-up (P>0.05). H2 treatment significantly reduced body fat percentage (3.2 vs. 0.9%, P=0.05) and arm fat index (9.7 vs. 6.0%, P=0.01) compared to placebo administration, respectively. This was accompanied by a significant drop in serum triglycerides after H2 intervention comparing to placebo (21.3 vs. 6.5%; P=0.04), while other blood lipids remained stable during the study (P>0.05). Fasting serum insulin levels dropped by 5.4% after H2 administration, while placebo intervention augmented insulin response by 29.3% (P=0.01). It appears that orally administered H2 as a blend of hydrogen-generating minerals might be a beneficial agent in the management of body composition and insulin resistance in obesity.

The Nature of the Isolated Gallium Active Center for Propane Dehydrogenation on Ga/SiO2

Single-site Ga/SiO2 catalysts exhibit up to 99% C3H6 selectivity at 4% propane conversion with an initial rate of 5.4 × 10−4 (mole C3H6) (mole Ga)−1 s−1 during propane dehydrogenation (PDH) at 550 °C. Following pre-treatment in H2 at 550 °C, only four-coordinate, Ga3+–O Lewis acid sites are observed under reaction conditions. At 650 °C in H2, an additional isolated Ga site with lower Ga–O coordination (N Ga−O < 4) is formed and leads to a 30% decrease in the initial PDH rate per total moles of Ga. The PDH rates are equivalent when normalized by the amount of surface, four-coordinate Ga3+–O, regardless of catalyst pre-treatment conditions, which indicates that these isolated Ga3+ centers are the catalytically relevant sites. Isolated, Lewis acidic Ga3+ cations present as four-coordinate Ga3+–O centers exhibit up to 99% C3H6 selectivity during propane dehydrogenation (PDH) at 550 °C. An additional isolated Ga site with lower Ga–O coordination is formed during H2 treatment at elevated temperatures, but is inactive for PDH and reversibly decomposes under reaction conditions.

The inhibitor role of NH3 on its synthesis process at low temperature, over Ru catalytic nanoparticles

Single catalysts containing 3, 5 and 7wt.% of Ru (Ru3/Al2O3, Ru5/Al2O3 and Ru7/Al2O3) were prepared via impregnation of alumina with RuO2 colloidal suspensions. Two mechanical mixtures, containing Ru3/Al2O3+Ru5/Al2O3 and Ru3/Al2O3+Ru7/Al2O3, were also prepared. Catalytic activity was measured during low-temperature ammonia synthesis reaction. Three different tests were performed after reduction pretreatment of the catalysts: 1) Standard test, the catalytic activity of ammonia synthesis; 2) Test under NH3+He treatment, following ammonia decomposition; 3) Test under NH3+He+H2 treatment, following ammonia decomposition in presence of hydrogen. Standard tests were additionally used to study the effect of the different treatments (NH3+He and NH3+He+H2) on the catalytic activity of ammonia synthesis. Catalysts were characterized by N2 physisorption, XRD and XPS spectroscopy. The size of Ru nanoparticles influences their performance during ammonia synthesis. The important role of the average size and size distribution of Ru nanoparticles in their activity for ammonia synthesis has been confirmed. Catalysts having a broad size distribution of Ru nanoparticles are more active than those having a narrow size distribution of Ru nanoparticles. Ammonia treatment has a negative effect in ammonia synthesis: results suggest that NHx intermediates remaining strongly adsorbed on the surface inhibit the activity of catalysts during ammonia synthesis. The presence of hydrogen during NH3 treatment inhibits ammonia decomposition and induces weaker adsorption of NHx intermediates. The presence of large particles is necessary to reach and maintain a high catalytic activity during ammonia synthesis. Taking into account previous studies, it could be suggested that large Ru nanoparticles activates mobile hydrogen atoms that migrate towards small Ru nanoparticles, promoting NHx hydrogenation. When mixing two catalysts having different mean Ru sizes, there is a significant synergistic effect in the catalytic activity, due to a more effective hydrogenation of NHx intermediates.

Gas-phase diagnostics during H2 and H2O plasma treatment of SnO2 nanomaterials: Implications for surface modification

Although H2O plasmas are commonly used to enhance the surface oxygen content of various materials, our prior study found that H2O plasma modification of SnO2 nanomaterials resulted in reduction of Sn+4 to Sn0. To further explore this phenomenon and develop a deeper understanding of the mechanism for this behavior, gas-phase species were detected via optical emission spectroscopy during H2O plasma processing (nominally an oxidizing environment), both with and without SnO2 substrates in the reactor. Gas-phase species were also detected in the reducing environment of H2 plasmas, which provided a comparative system without oxygen. Sn* and OH* appear in the gas phase in both plasma systems when SnO2 nanowire or nanoparticle substrates are present, indicative of SnO2 etching. Furthermore, H2 and H2O plasmas reduced the Sn in both nanomaterial morphologies. Differences in H* and OH* emission intensities as a function of plasma parameters show that plasma species interact differently with the two SnO2 morphologies. The H2O plasma gas-phase studies found that under most plasma parameters, the ratio of reducing to oxidizing gas-phase species was ≥1, indicating a reducing environment rather than an oxidizing environment.

PtOx-SnOx-TiO2 catalyst system for methanol photocatalytic reforming: Influence of cocatalysts on the hydrogen production

Effects of modification of PtOx-TiO2 photocatalysts by tin were elucidated by exploring relationships between the structural properties of variously prepared tin-loaded catalysts and their catalytic activity in methanol photocatalytic reforming. Tin free and amorphous tin-oxide decorated TiO2 samples were prepared by sol-gel method from titanium-isopropoxide. In other approach, Sn was loaded onto the sol-gel prepared TiO2 by impregnation followed by calcination. Pt was introduced by impregnation followed by either reduction in H2 at 400°C or calcination at 300°C. TEM, XRD and Raman spectroscopic measurements proved that TiO2 existed in the form of aggregates of polycrystalline anatase with primary particle size of 15–20nm in all samples. Photocatalytic hydrogen production was influenced by the combined effect of many parameters. Both the presence of Sn and the way of Pt co-catalyst formation played important role in the activity of these photocatalysts. The Sn introduction by both sol-gel method and impregnation clearly enhanced the photocatalytic activity. 1H MAS NMR measurements revealed that the Sn introduction reduced the amount of the terminal Ti-OH groups of relatively basic character considered to be unfavorable for the photocatalytic reaction. Presence of SnOx decreased the signal of the undesirable vacancies observed by ESR. Furthermore surface SnOx enhanced the dispersion of Pt. Formation of the Pt co-catalyst by calcination was more favorable than by H2 treatment. In case of the calcined samples in situ reduction of the Pt nanoparticles at the beginning of the photocatalytic reaction was found to be favorable for the hydrogen production. The relatively modest photocatalytical activity obtained after high temperature H2 treatment could be related to at least two processes in this system: (i) creation of unfavorable oxygen vacancies and (ii) segregation of SnOx to the surface of the Pt cocatalyst as the result of the air exposure of the alloy type Pt-Sn nanoparticles formed during the H2 treatment, resulting in a decreased number of active sites for reduction of H+.

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.

Hydrogen generation via ethanol steam reforming over Co/HAp catalysts

The catalytic activity of calcium hydroxyapatite (HAp) supported cobalt nanoparticles in ethanol steam reforming (SRE) was investigated. Co was supported on hydrothermally prepared HAp by incipient wetness impregnation method. Co/HAp catalysts were characterized through XRD, FT-IR and Raman spectroscopy, TEM, SEM/EDS, N2 physisorption, TG and TPR-H2. Results showed that spinel cobalt oxide is reduced to CoO and Co and these species are responsible for catalytic activity for hydrogen production via SRE process. The main reactions over Co/HAp are incomplete steam reforming and dehydrogenation of ethanol. Reforming experiment over pre-reduced sample indicated a negative impact of H2 treatment on hydrogen production. The best catalytic properties (YH2 and CEtOH) were obtained over 5%Co/HAp catalyst.

Role of limited hydrogen and flow interval on the growth of single crystal to continuous graphene by low-pressure chemical vapor deposition

A method for defect-free large crystallite graphene growth remains unknown despite much research effort. In this work, we discuss the role of flow duration of H2 gas for the production of graphene as per requirement and production at a minimum flow rate considering the safety issue of hydrogen utilization. The copper substrate used for growth was treated for different time intervals (0 to 35 min) in H2 flow prior to growth. Structural and chemical changes occurring in the copper substrate surface were probed by grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy. The results were correlated with the Raman spectroscopy data, which can quantify the quality of graphene. With increasing H2 flow interval, secondary nucleation sites were observed and growth favored few-layer graphene structures. The surface-adsorbed oxygen molecules and its conversion to an OH terminated surface with increasing hydrogen flow interval was found to be a key factor in enhancing nucleation density. The Stranski–Krastanov type of nucleation was observed for samples grown with different time intervals of H2 treatment, except 5 min of H2 flow prior to growth for which the Volmer–Weber type of growth favored monolayer graphene crystallite growth.

Formation mechanism of zeolite-templated carbons

The formation mechanism of zeolite-templated carbons (ZTCs) is investigated. The carbon uptake into zeolite nanochannels during chemical vapor deposition (CVD) is found to proceed in the following three stages: (i) initial rapid carbon uptake from zeolite-particle surface to its center, (ii) gradual increase of carbon density at a constant rate, and (iii) termination of carbon deposition. The molecular-level structure evolution is also analyzed in detail. By CVD, curved nanographenes are formed inside the nanochannels of zeolite, and they are not perfectly connected each other. The subsequent heat treatment (>800 °C) coalesces the nanographenes to form a continuous 3D framework, and at the same time, a significant number of dangling bonds (non-terminated edge sites) are formed that are protected from air by the zeolite so that they are stable at room temperature. However on template removal, the dangling bonds react with ambient H2O or O2 and are terminated by oxygen-functional groups or H. The dangling bonds in the carbon/zeolite composite can also be terminated by H when the composite is subjected to a H2 treatment at 700 °C. In this case, the number of dangling bonds in the carbon/zeolite composite is decreased, and the addition of oxygen-functional groups when the template is removed becomes less significant.

Selective hydrogenation of unsaturated carbonyls by Ni–Fe-based alloy catalysts

Ni–Fe alloy catalysts prepared by a simple hydrothermal method and subsequent H2 treatment were shown to be highly selective for the hydrogenation of various unsaturated carbonyls.

Starch-enhanced degradation of HMW PAHs by Fusarium sp. in an aged polluted soil from a coal mining area

The present study used strain ZH-H2 (Fusarium sp.) isolated by our group as the PAH-degrading strain and 5-6-rings PAHs as degradation objects. The soil incubation experiment was carried out to investigate the starch-enhanced degradation effects of HMW PAHs by Fusarium sp. in an Aged Polluted Soil from a Coal Mining Area. The results showed that the removal rates of BaP, InP and BghiP increased with increasing inoculation rate of ZH-H2 in the unsterile aged polluted soil of coal mining area, with the exception of BbF degradation which increased in the H2 treatment and then decreased. Different addition dosage of starch apparently resulted in degradation of 4 PAHs in soil, with removal rates of 14.47% for BaP, 23.83% for DbA, 30.77% for BghiP and 31.00% for InP obtained with treatment D2, respectively higher than in treatment D1. So starch addition apparently enhanced the degradation of the 4 PAHs, especially InP and BghiP, by native microbes in the aged HMW PAH-polluted soil. By adding starch to these aged polluted soils with inoculated strain ZH-H2, HMW-PAHs degradation was further improved and addition of 0.5 g kg−1 starch to soils with 1.0 g kg−1 Fusarium ZH-H2 (D2 + H2) performed best to the 4 HMW-PAHs in all of these combination treatments by a factor of up to 3.09, depending on the PAH. We found that the highest polyphenol oxidase activities under D2 + H2 treatments are consistent with the results of removal rates of 4 PAHs. Our findings suggest that the combination of Fusarium sp. ZH-H2 and starch offers a suitable alternative for bioremediation of aged PAH-contaminated soil in coal mining areas, with a recommended inoculation size of 0.5 g Fusarium sp. ZH-H2 and addition of 0.5 g kg−1 starch per kg soil.

Surface activation inspires high performance of ultra-thin Pd membrane for hydrogen separation

Pd-based membranes play a critical role in the field of hydrogen purification and small-scale hydrogen generation. The microstructure and composition of ultra-thin Pd membranes immediately determines their performance and stability, which are however complex and elusive. We applied for the first time a novel technique of environmental scanning electron microscopy (ESEM) together with EDS analysis for in-situ investigation of microstructure and composition of Pd composite membranes under gas-thermal treatment. It enables step by step analysis of the evolution process and offers more meticulous details compared to ex-situ technologies through analysis at exactly the same location of membrane samples. Here we observed the elimination of Pd crystallites as well as the homogenization/diffusion along the whole membrane surface following high T treatment under inert gas or H2 atmosphere. Gradual evolution of microhillocks on Pd membrane surface was resulted due to α−β phase transition or exposure to either O2 or H2O, which can be effectively “smoothened” out during H2 treatment. The exposure to steam exhibited a mild oxidation effect without pinhole formations, which appears a more appropriate surface cleaning process compared to air/oxygen treatment. A significant interlayer diffusion was revealed between Pd layer and ZrO2/alumina substrate in H2/O2/H2O atmosphere.

Transcriptome Analysis of mRNA and miRNA in Somatic Embryos of Larix leptolepis Subjected to Hydrogen Treatment.

Hydrogen is a therapeutic antioxidant that has been used extensively in clinical trials. It also acts as a bioactive molecule that can alleviate abiotic stress in plants. However, the biological effects of hydrogen in somatic embryos and the underlying molecular basis remain largely unknown. In this study, the morphological and physiological influence of exogenous H2 treatment during somatic embryogenesis was characterized in Larix leptolepis Gordon. The results showed that exposure to hydrogen increased the proportions of active pro-embryogenic cells and normal somatic embryos. We sequenced mRNA and microRNA (miRNA) libraries to identify global transcriptome changes at different time points during H2 treatment of larch pro-embryogenic masses (PEMs). A total of 45,393 mRNAs and 315 miRNAs were obtained. Among them, 4253 genes and 96 miRNAs were differentially expressed in the hydrogen-treated libraries compared with the control. Further, a large number of the differentially expressed mRNAs and miRNAs were related to reactive oxygen species (ROS) homeostasis and cell cycle regulation. We also identified 4399 potential target genes for 285 of the miRNAs. The differential expression data and the mRNA-miRNA interaction network described here provide new insights into the molecular mechanisms that determine the performance of PEMs exposed to H2 during somatic embryogenesis.

Effects of catalyst configurations and process conditions on the formation of catalyst nanoparticles and growth of single-walled carbon nanotubes

The synthesis of well-aligned and type-enriched semiconducting single-walled carbon nanotubes (sc-SWCNTs) with high quality by means of catalytic chemical vapour deposition (CCVD) on wafer-level are essential prerequisites for the implementation of nanodevices for sensor and electronic applications. In particular, the Co-Mo bilayer catalyst system is promising due to its ability to grow semiconducting enriched SWCNTs by CCVD. However, there is still a gap in understanding how to adjust catalyst properties aiming further improvements in SWCNTs film composition and morphology. In particular, surface morphological evolution during catalyst conditioning as well as its impact on SWCNT growth are not clearly understood. Here we present a systematic investigation on effects of catalyst support layer, catalyst preparation conditions, catalyst type and composition as well as gas composition for catalyst treatments on the size of catalyst nanoparticles (NPs) and the properties of CCVD grown SWCNTs. We show that H2 treatment favors the formation of small catalyst NPs with narrow size distribution in the case of Al2O3 support layer. Moreover, we correlate the growth rates, quality of SWCNTs structures and sc-SWCNTs content with the Co-Mo catalyst morphological evolution.