Effects of Hydrogen on Behaviour of Low Cycle Fatigue of 2.25Cr-1Mo Steel

The effects of hydrogen atoms on behaviour of low cycle fatigue of 2.25Cr-1Mo steel have been investigated in present work. The results indicate that the cyclic softening rate and low cycle fatigue life are respectively increased and reduced remarkably by hydrogen atoms. In addition, hydrogen atoms make the original stress amplitude of low cycle fatigue increase, which is because of the drag effect of hydrogen atoms on the moving dislocations. Analyses using electron microscopy show that hydrogen atoms accelerate crack initiation of low cycle fatigue from inclusion and transfer the source of low cycle fatigue crack from the surface of specimen to the inclusion, which results in the marked decrease of low cycle fatigue life. The increase of cyclic softening rate for hydrogen charged specimen is due to hydrogen atoms accelerating the initiating and growing of microvoids from the secondary phase particles in the steel. The reducing of the drag effect of hydrogen atoms on moving dislocations is also helpful to the increase of the cyclic softening rate.

Helium-hydrogen synergistic effects on swelling in in-situ multiple-ion beams irradiated steels

The development of reliable fusion energy is one of the most important challenges in this century.The accelerated degradation of structural materials in fusion reactors caused by neutron irradiation would cause severe problems.Due to the lack of suitable fusion neutron testing facilities,we have to rely on ion irradiation experiments to test candidate materials in fusion reactors.Moreover,fusion neutron irradiation effects are accompanied by the simultaneous transmutation production of helium and hydrogen.One important method to study the He-H synergistic effects in materials is multiple simultaneous ion beams(MSIB)irradiation that has been studied for decades.To date,there is no convincing conclusion on these He-H synergistic effects among these experiments.Recently,a multiple ion beam in-situ transmission electron microscopy(TEM)analysis facility was developed in Xiamen University(XIAMEN facility),which is the first triple beam system and the only in-running in-situ irradiation facility with TEM in China.In this work,we conducted the first high-temperature triple simultaneous ion beams irradiation experiment with TEM observation using the XIAMEN facility.The responses to in-situ triple-ion beams irradiation in austenitic steel 304L SS and ferritic/martensitic steel CLF-1 were studied and compared with the results in dual-and single-ion beam(s)irradiated steels.Synergistic effects were observed in MSIB irradiated steels.Helium was found to be critical for cavity formation,while hydrogen has strong synergistic effect on increasing swelling.

Irradiation Effects on the Retention of Hydrogen in Al_2O_3

Substantial defects are produced in Al2O3 by 4 MeV Au ion irradiation with a fluence of 4.4×10^15 cm^-2. Ruther- ford baekscattering spectrometry/channeling and cross-sectional transmission electron microscopy methods are used to investigate the irradiation damage. The 190keV H ions with a fuence of 1×10^17 cm^-2 are used for implanting pristine and Au ion irradiated Al2O3 to explore the irradiation damage effects on the hydrogen retention in Al2O3. The time-of-flight secondary ion mass spectrometry method is used to obtaJn the single hydrogen depth profile and ions mass spectra （IMS）, in which we find that implanted hydrogens interacted with defects produced by Au ion irradiation. In IMS, we also obtain the hydrogen retention at a certain depth. Comparing the hydrogen retention in different Al2O3 samples, it is concluded that the irradiation damage improves the tritium permeation resistance property of Al2O3 under given conditions. This result means that Al2O3 may strengthen its property of reduc/ng tritium permeation under the harsh irradiation environment in fusion reactors.

Effects of Hydrogen on the Methane Coupling under Non-equilibrium Plasma

In this paper, hydrogen is first utilized in the study on methane coupling under nonequilibrium plasma. Results indicate that the addition of hydrogen is beneficial. to the methane coupling so as to increase the conversion rate of methane and the yield of C2 hydrocarbon with a gradual increase in the addition of hydrogen in a certain range of proportionality. This conclusion explores a new route of hydrogenated methane coupling.

EFFECTS OF RARE EARTH METAL ON HYDROGEN BEHAVIOUR IN STEEL 16Mn

The slow tensile tests,dynamic hydrogen charging tensile tests and hydrogen evolution tests after hydrogen charging were used to study the effects of rare earth metal(REM)on hydrogen behaviour in a steel 16Mn(St.52).The ratios of RE/S were chosen as 0,0.7,2.2 and 7.7,respectively.It was shown that the steel with RE/S = 2.2 give a lower hydrogen embrittlement susceptibility than others.The steels without REM can adsorb much more amount of hydrogen than that with REM under the same hydrogen charging conditions.And the amount of adsorbed hydrogen for the foriner can be evolved easier than that for the latter at room temperature,50℃ and 80℃,respectively.The experimental results were explained by the trap theory of hydrogen,the short-circuit diffusion paths in the interfaces between the elongated MnS inclusions and the matrix,and strong ability of REM to adsorb hydrogen.

Strain engineering and hydrogen effect for two-dimensional ferroelectricity in monolayer group-Ⅳmonochalcogenides MX(M=Sn,Ge;X=Se,Te,S)

Two-dimensional(2D)ferroelectric compounds are a special class of materials that meet the need for devices miniaturization,which can lead to a wide range of applications.Here,we investigate ferroelectric properties of monolayer group-IV monochalcogenides MX(M=Sn,Ge;X=Se,Te,S)via strain engineering,and their effects with contaminated hydrogen are also discussed.GeSe,GeTe,and GeS do not go through transition up to the compressive strain of-5%,and consequently have good ferroelectric parameters for device applications that can be further improved by applying strain.According to the calculated ferroelectric properties and the band gaps of these materials,we find that their band gap can be adjusted by strain for excellent photovoltaic applications.In addition,we have determined the most stable hydrogen occupancy location in the monolayer SnS and SnTe.It reveals that H prefers to absorb on SnS and SnTe monolayers as molecules rather than atomic H.As a result,hydrogen molecules have little effect on the polarization and electronic structure of monolayer SnTe and SnS.

Role of hydrogen bonding in solubility of poly(N-isopropylacrylamide) brushes in sodium halide solutions

By employing molecular theory, we systematically investigate the shift of solubility of poly（N-isopropylacrylamide）（PNIPAM） brushes in sodium halide solutions. After considering PNIPAM–water hydrogen bonds, water–anion hydrogen bonds, and PNIPAM–anion bonds and their explicit coupling to the PNIPAM conformations, we find that increasing temperature lowers the solubility of PNIPAM, and results in a collapse of the layer at high enough temperatures. The combination of the three types of bonds would yield a decrease in the solubility of PNIPAM following the Hofmeister series： Na Cl＆gt;Na Br＆gt;Na I. PNIPAM–water hydrogen bonds are affected by water–anion hydrogen bonds and PNIPAM–anion bonds. The coupling of polymer conformations and the competition among the three types of bonds are essential for describing correctly a decrease in the solubility of PNIPAM brushes, which is determined by the free energy associated with the formation of the three types of bonds. Our results agree well with the experimental observations, and would be very important for understanding the shift of the lower critical solution temperature of PNIPAM brushes following the Hofmeister series.

Hydrogen Fixation Effect of Rare Earths in Pure Aluminium and Aluminium Alloys

The areal distribution of some elements in the rare earth bearing spheroidal phases in pure aluminium and Al-Mn alloys was studied by SIMS(secondary ion mass spectrometry).The results show that cerium,iron. silicon and hydrogen are significantly segregated in the phases.Thus the existence of hydrogen-rich rare earth bearing eompounds is confirmed.It indicates that the rare earths have a hydrogen fixation effect in aluminium and aluminium alloys.

Effect of Hydrogen Charging on the Tensile and Constant Load Properties of an Austenitic Stainless Steel Weldment

The effect of cathodic hydrogen charging on the tensile and constant load properties was deter- mined for an austenitic stainless steel weldment comprising a 304L steel in the solution treated condition as a base metal and a 308L filler steel as a weld metal. Part of the 304L solution treated steel was separately given additional sensitization treatment to simulate the microstructure that would develop in the heat affected zone. Tests were performed at room temperature on notched round bar specimens. Hydrogen charging resulted in a pronounced embrittlement of the tested materials. This was manifested mainly as a considerable loss in the ductility of tensile specimens and a decrease in the time to failure and threshold stress of constant load specimens. The 308L weld metal exhibited the highest, and the 304L solution treated steel the lowest, resistance to hydrogen embrittlement. Hydrogen embrittlement was associated with the formation of strain induced martensite as well as a transition from brittle to ductile fracture morphology onwards the centre of the specimens.

EFFECT OF HYDROGEN BONDING ON DIRECTION OF PHOTOISOMERIZATION OF RETINOIDS:THE ORIGIN OF THE SOLVENT POLARITY EFFECT.

Studies of direction of photoisomerization of retinal,retinonitrile,a- retinonitrile and a trienenitrile analog in different solvents with varying wave- lengths of excitation and reaction temperature led to the conclusion that the well known solvent dependent photochemistry of retinoids is due to selective excitation of the hydrogen bonded species.

EFFECT OF ELECTRON DONORS ON THE SELECTIVE HYDROGENATION OF DIENE TO MONOENE OVER HETEROGENIZED Pd CATALYST

In the selective hydrogenation of diene (or alkyne) using heterogenized homogeneous catalyst, the high selectivity of monoene formation only appears in a very short time interval. The addition of suitable electron donors can decrease or even cease the monoene hydrogenation and thereby keep the high monoene selectivity after reaching its maximum.

Evaluation of the effect of hydrogen sulfide postconditioning by p-v loop against myocardial i/r injury in rats

Objectives To evaluate the effect of hydrogen sulfide(H2S) postconditioning on myocardial ischemia-reperfusion (I/R) by pressure-volume loop(P-V loop). Methods The I/R model of rat in vivo was established by ligating the left anterior descending coronary artery for 30min and reperfusing for 120 min.Wistar rats(n=32) were ran- domly divided into 4 groups;Sham operation,ischemia-reperfusion (I/R),Ischemic postconditioning(IPO) and H2S postconditioning.In sham operation,there was no ligation.In IPO,at the start of reperfusion,three cycles of 30s reperfusion and 30s LAD reocclusion preceded the 3h of reperfusion. In H2S postconditioning,NaHS(15μmol/kg,Sodium hydrosulfide)was administrated before coronary artery reperfusion. The heart rate(HR),I/R arrhythmia,the left ventricular end-systolic pressure(LVESP),left ventricular enddiastolic pressure(LVEDP),the slope of the end- systolic P-V relation(ESPVR) and the slope of the end-diastolic P-V relation(EDPVR) were detected.Infarct size was determined by scanning the images of the rat heart ventricular sections stained with Evans blue and TTC.Results Compared with I/R group,the I/R arrhythmia and the infarct size were decreased significantly(PPP2S postconditioning group.Conclusions Myocardial I/R injury was decreased by H2S post-conditioning, and it was sensitive and accurate to evaluate the heart function by P-V loop.

Effect of Chromium on Structure and Tribological Properties of Hydrogenated Cr/a-C:H Films Prepared via a Reactive Magnetron Sputtering System

Hydrogenated Cr-incorporated carbon films （Cr/a-C：H） are deposited successfully by using a dc reactive mag- netron sputtering system. The structure and mechanical properties of the as-deposited Cr/a-C：H films are characterized systematically by field-emission scanning electron microscope, x-ray diffraction, Raman spectra, nanoindentation and scratch. It is shown that optimal Cr metal forms nanocrystalline carbide to improve the hardness, toughness and adhesion strength in the amorphous carbon matrix, which possesses relatively higher nano-hardness of 15. 7 CPa, elastic modulus of 126.8 GPa and best adhesion strength with critical load （Lc） of 36 N for the Cr/a-C：H film deposited at CH4 flow rate of 20sccm. The friction and wear behaviors of as-deposited Cr/a-C：H films are evaluated under both the ambient air and deionized water conditions. The results reveal that it can achieve superior low friction and anti-wear performance for the Cr/a-C：H film deposited at CH4 flow rate of 20sccm under the ambient air condition, and the friction coetllcient and wear rate tested in deionized water condition are relatively lower compared with those tested under the ambient air condition for each film. Superior combination of mechanical and tribological properties for the Cr/a-C：H film should be a good candidate for engineering applications.

Hydrogen isotope effects: A new path to high-energy aqueous rechargeable Li/Na-ion batteries

Aqueous rechargeable Li/Na-ion batteries have shown promise for sustainable large-scale energy storage due to their safety,low cost,and environmental benignity.However,practical applications of aqueous batteries are plagued by water's intrinsically narrow electrochemical stability window,which results in low energy density.In this perspective article,we review several strategies to broaden the electrochemical window of aqueous electrolytes and realize high-energy aqueous batteries.Specifically,we highlight our recent findings on stabilizing aqueous Li storage electrochemistry using a deuterium dioxide-based aqueous electrolyte,which shows significant hydrogen isotope effects that trigger a wider electrochemical window and inhibit detrimental parasitic processes.

Damage mechanism of hydroxyl radicals toward adenine–thymine base pair

The adenine-thymine base pair was studied in the presence of hydroxyl radicals in order to probe the hydrogen bond effect. The results show that the hydrogen bonds have little effect on the hydroxylation and dehydrogenation happened at the sites, which are not involved in a hydrogen bond, while at the sites involved in hydrogen bond formation in the base pair, the reaction becomes more difficult, both in view of the free energy barrier and the exothermicity. With a 6-311 ＋＋G（d,p） level of description, both B3LYP and MP2 methods confirm that the C8 site of isolated adenine has the highest possibility to form covalent bond with the hydroxyl radicals, though with different energetics： B3LYP predicts a barrierless pathway, while MP2 finds a transition state with an energy of 106.1 kJ/mol. For the dehydrogenation reactions, B3LYP method predicts that the free energy barrier increases in the order of HN9 〈 HN61 〈 HN62 〈 H2 〈 H8.

Substituent Effects on the Hydrogen Bonding between 4-Substituted Phenols and HF,H_2O,NH_3

Density function theory UB3LYP/6-31+g(d) calculations were performed to study the hydrogen bonds between para -substituted phenols and HF,H_2O,or NH_3. It revealed that many properties of the non-covalent complexes,such as the interaction energies,donor-acceptor distances,bond lengths and vibration frequencies,showed well-defined substituent effects. Therefore,from the substituent effects not only the mechanism of a certain non-covalent interaction can be better understood,but also the interaction energies and structures of a certain non-covalent complex,which otherwise might be very hard or resource-consuming to estimate,can be easily predicted.

Role of hydrogen in stability and mobility of vacancy clusters in tungsten

We investigated the influence of hydrogen(H)on the stability and mobility of small vacancy clusters in tungsten(W)using the first-principles calculations.It is found that the presence of H not only increases the binding energy of small vacancy clusters but also changes their most favorable configurations,owing to the strong attractive interaction between H and vacancies in W.Specifically,the binding energy of di-vacancy changes from negative to positive when the H atoms are introduced.These results suggest that the H addition can significantly promote the stability of small vacancy clusters in W.More importantly,although the migration energy barriers of H-vacancy(H-V)complexes are slightly higher than that of pure vacancy clusters,the activation energy required for complexes migration is always lower than that for dissociation.Therefore,contrary to the conventional view,the collaborative motion of H and small vacancy clusters is possible,because of the low migration energy barriers.Based on the energetic results obtained by first-principles calculations,the mean lifetime and mean diffusion distance of small H-V complexes at different temperatures are examined by the object kinetic Monte Carlo simulations.The small H-V complexes are found to be stable and mobile at moderate temperature,and thus may affect the co-evolution of H and vacancies.These results shed light on the important role of H on the vacancy behaviors and provide a good reference for understanding the defects evolution in W.

Hydrogen sulfide and vascular relaxation

Objective To review the vasorelaxant effects of hydrogen sulfide （H2S） in arterial rings in the cardiovascular system under both physiological and pathophysiological conditions and the possible mechanisms involved. Data sources The data in this review were obtained from Medline and Pubmed sources from 1997 to 2011 using the search terms ＂hydrogen sulfide＂ and ＂vascular relaxation＂. Study selection Articles describing the role of hydrogen sulfide in the regulation of vascular activity and its vasorelaxant effects were selected. Results H2S plays an important role in the regulation of cardiovascular tone. The vasomodulatory effects of H2S depend on factors including concentration, species and tissue type. The H2S donor, sodium hydrosulfide （NariS）, causes vasorelaxation of rat isolated aortic rings in a dose-dependent manner. This effect was more pronounced than that observed in pulmonary arterial rings. The expression of KATp channel proteins and mRNA in the aortic rings was increased compared with pulmonary artery rings. H2S is involved in the pathogenesis of a variety of cardiovascular diseases. Downregulation of the endogenous H2S pathway is an important factor in the pathogenesis of cardiovascular diseases. The vasorelaxant effects of H2S have been shown to be mediated by activation of KATP channels in vascular smooth muscle cells and via the induction of acidification due to activation of the Cr/HCO3 exchanger. It is speculated that the mechanisms underlying the vasoconstrictive function of H2S in the aortic rings involves decreased NO production and inhibition of cAMP accumulation. Conclusion H2S is an important endogenous gasotransmitter in the cardiovascular system and acts as a modulator of vascular tone in the homeostatic regulation of blood pressure.

Molybdenum-doped titanium dioxide supported low-Pt electrocatalyst for highly efficient and stable hydrogen evolution reaction

The Platinum(Pt)-based catalysts exhibit excellent catalytic performance for the hydrogen evolution reaction(HER) while suffering from poor stability due to the weak interaction between the carbon support and Pt.Herein,a molybdenum-doped titanium dioxide(Ti_(0.9)Mo_(0.1)O_(2)) supported low-Pt electrocatalyst with stronger interaction between catalyst and support is applied to tune the electrocatalytic performance of Pt.The Ti_(0.9)Mo_(0.1)O_(2) support can not only tolerate the corrosion environment in the catalytic system,but also generate strong metal-support inte raction(SMSI) between the oxide and catalyst.A facile solvothermal method is used to prepareTi_(0.9)Mo_(0.1)O_(2) as support to anchor Pt nanoparticles.The 5% Pt supported on Ti_(0.9)Mo_(0.1)O_(2) catalyst exhibits 4.4-fold mass activity(MA) at an overpotential of 50 mV and higher stability than 20% Pt/C with only 1/4 Pt loading.The SMSI between the Ti_(0.9)Mo_(0.1)O_(2) and Pt prevents the Pt aggregation to achieve excellent stability,and hydrogen spillover effect in the interface between Pt and support benefits the hydrogen production process.This work presents a novel sight for the fabrication and design of oxide supported catalysts in various catalytic system by reasonably employing support effect.

A NEW EPR DEFECT IN NEUTRON-IRRADIATED FZ-SILICON AND HYDROGEN PASSIVATION EFFECT

A new EPR center having C2v symmetry and S=1, labeled as Si-PK3, has been observed for the first time in neutron-irradiated FZ-silicon. The spectra start to appear after 150℃ annealing and disappear at 500℃. The principal values of tensor g and D are determined. The microscopic model is proposed to be a trivacancy chain along the 〈110〉-direction with an oxygen atom situated in the middle. The annealing temperature of si-PK3 in hydrogencontaining samples is at least by 150℃ lower than that of other samples.