Influence of thermo hydrogen treatment on microstructure and mechanical properties of Ti-5Al-2.5Sn ELI alloy

Thermo hydrogen treatment （THT） of titanium is a process in which hydrogen is used as a temporary alloying element in titanium alloys. It is an attractive approach for controlling the microstructure and thereby improving the final mechanical properties. In the present study, the microstructure of the original （non-hydrogenated） sample has only a phase and the grains is coarse with an average size of - 650 pm. While the grain size of thermo hydrogen treated Ti-5Al-2.5Sn ELI alloy became finer and the mechanical properties were improved significantly. When the hydrogen content of the hydrogenated Ti-5Al-2.5Sn ELI alloy is 0.321wt.%, 13 phase and 6 titanium hydride appear. Also the average grain size decreases to 450 pm. When the hydrogen content is 0.515wt.%, the grain size decreases to 220μm. The mechanical properties were tested after dehydrogenation, and the mechanical properties improved significantly compared to the unhydrogenated specimens. The tensile strength of the Ti-5Al- 2.5Sn ELI alloy improved by 17.7% when the hydrogen content increased to 0.920wt.%, at the same time the percentage reduction of area （Z） increased by 33% and the impact toughness increased by 37%.

EFFECT OF HYDROGENATION ON THE MICROSTRRUCTURE OFTi-24Al-14Nb-3V-0.5Mo ALLOY

The ebct of hydrogenation-dehydrogenation on the microstructure of forping Ti-24Al14Nb-3V-0.5MO alloy was investigated by TEM and X-ray ddection. The resultsshowed that the microstructure consists of O and B2 phases as received materials, and tmoprmation of B2 phase to O phase can be eNctively promoted 6y hydrogenation. The lamellate γ hydride was found in O phase with more hydmpen content, and this γ hydride could be decomposed by dehydmpenation treatment. The sole fine Ophase could be obtained 6y hydmpenation-dehydmpenation treatment, and two possible mechanisms for the microstructure improvetnent have been discussed on the basis of experimental results.

Surface Modification of AB_2 and AB_5 Hydrogen Storage Alloy Electrodes by the Hot-Charging Treatment

The effect of the hot-charging treatment on the performance of AB(2) and AB(5) hydrogen storage alloy electrodes was investigated. The result showed that the treatment can markedly improve the voltage plateau ratio (VPR), the high rate discharge ability (HRDA), the diffusion coefficient of hydrogen DH and the discharge capacity of the AB2 hydrogen storage alloy electrode. The SEM analysis showed that the hot-charging treatment brings about a Ni-rich surface due to the dissolution of Zr oxides. It is also very helpful for the improvement of the kinetic properties of AB2 hydrogen storage alloy electrode because the microcracking of the surface results in fresh surface. This can be the basic modification treatment for NiMH battery used in electric vehicles (EVs) in the future. But for AB(5) type alloys, the treatment has the disadvantage of impairing the comprehensive electrochemical properties, because the surface of the alloy may be corroded during the treatment. The mechanism of the surface modification of the electrode is also proposed.

THE IMPROVEMENT OF ELECTRON FIELD EMISSION FROM AMORPHOUS CARBON FILMS DUE TO HYDROGEN PLASMA CHEMICAL ANNEALING EFFECT

Hydrogenated amorphous carbon films were fabricated by using layer-by-layer deposition method and hydrogen dilution method in a small d.c.-assisted plasma enhanced chemical vapor deposition system. It was found that the hydrogen plasma treatment could change the sp2/sp3 ratio to some extent by chemical etching. The improvements of field emission characteristics were observed compared with that from conventionally deposited a-C films, which can be attributed to the large field enhancement effect due to the inhomogeneous distribution of nanometer scale sp2 clusters and the reduction of the surface emission barrier due to the hydrogen termination.

Engineering vacancies for solar photocatalytic applications

In contrast to the exploration of novel photocatalytic materials,vacancy engineering of traditionalphotocatalysts comprising earth‐abundant elements represents an effective method for enhancingphotocatalytic performance without introducing alien elements.This minireview analyzes the latestprogress in engineering vacancies in photocatalysts,remarks on state‐of‐the‐art characterizationtechniques for vacancies,and reviews the formation chemistry and fundamental benefits of anionand cation vacancies in typical photocatalysts.Although knowledge of these vacancies is increasing,challenges remain in this field,and possible further research is therefore also discussed.

Nanocrystalline Mg and Mg alloy powders by hydriding-dehydriding processing

The process of mechanically assisted hydriding and subsequent thermal dehydriding was proposed to produce nanocrystalline Mg and Mg alloy powders using pure Mg and Mg-5.5%Zn-0.6%Zr(mass fraction)(ZK60 Mg) alloy as the starting materal.The hydriding was achieved by room-temperature reaction milling in hydrogen.The dehydriding was carried out by vacuum annealing of the as-milled powders.The microstructure and morphology of both the as-milled and subsequently dehydrided powders were characterized by X-ray diffraction analysis(XRD) ,transmission electron microscopy(TEM) ,and scanning electron microscopy(SEM) ,respectively.The results show that,by reaction milling in hydrogen,both Mg and ZK60 Mg alloy can be fully hydrided to form nanocrystalline MgH2 with an average grain size of 10 nm.After subsequent thermal dehydriding at 300℃,the MgH2 can be turned into Mg again,and the newly formed Mg grains are nanocrystallines,with an average grain size of 25 nm.

A hypothesis for treating inflammation and oxidative stress with hydrogen sulfide during age-related macular degeneration

Age-related macular degeneration（AMD） is a leading cause of blindness and is becoming a global crisis since affected people will increase to 288 million by 2040.Genetics,age,diabetes,gender,obesity,hypertension,race,hyperopia,iris-color,smoking,sun-light and pyroptosis have varying roles in AMD,but oxidative stress-induced inflammation remains a significant driver of pathobiology.Eye is a unique organ as it contains a remarkable oxygengradient that generates reactive oxygen species（ROS） which upregulates inflammatory pathways.ROS becomes a source of functional and morphological impairments in retinal pigment epithelium（RPE）,endothelial cells and retinal ganglion cells.Reports demonstrated that hydrogen sulfide（H2S） acts as a signaling molecule and that it may treat ailments.Therefore,we propose a novel hypothesis that H2S may restore homeostasis in the eyes thereby reducing damage caused by oxidative injury and inflammation.Since H_2S has been shown to be a powerful antioxidant because of its free-radicals＇ inhibition properties in addition to its beneficial effects in age-relatedconditions,therefore,patients may benefit from H2S salubrious effects not only by minimizing their oxidant and inflammatory injuries to retina but also by lowering retinal glutamate excitotoxicity.

Synthesis of ZnO films with a special texture and enhanced field emission properties

ZnO films with special textures ave fabricated on Mo-coated Al2O3 ceramic substrates by the catalyst-free electron beam evaporation method, and the as-deposited films are treated by hydrogen plasma. It is found that the surface morphologies of the films are changed significantly after hydrogen plasma treatment and that the films consist of vertically standing and intersecting nanosheets. A lower turn-on field of 1.2 V/μm and an enhanced current density -0.11 mA/cm2 at 2.47 V/μm are achieved. The low threshold field and the high emission current density are attributed primarily to the unique shape and smaller resistivity of the ZnO nanosheet films.

Electrical and optical properties of hydrogen plasma treatedβ-Ga_(2)O_(3) thin films

The behavior of H inβ-Ga_(2)O_(3) is of substantial interest because it is a common residual impurity that is present inβ-Ga_(2)O_(3),regardless of the synthesis methods.Herein,we report the influences of H-plasma exposure on the electric and optical properties of the heteroepitaxialβ-Ga_(2)O_(3) thin films grown on sapphire substrates by chemical vapor deposition.The results in-dicate that the H incorporation leads to a significantly increased electrical conductivity,a greatly reduced defect-related photolu-minescence emission,and a slightly enhanced transmittance,while it has little effect on the crystalline quality of theβ-Ga_(2)O_(3) films.The significant changes in the electrical and optical properties ofβ-Ga_(2)O_(3) may originate from the formation of shallow donor states and the passivation of the defects by the incorporated H.Temperature dependent electrical properties of the H-in-corporatedβ-Ga_(2)O_(3) films are also investigated,and the dominant scattering mechanisms at various temperatures are dis-cussed.

Experimental Design Technique on Removal of Hydrogen Sulfide using CaO-eggshells Dispersed onto Palm Kernel Shell Activated Carbon：Experiment,Optimization,Equilibrium and Kinetic Studies

This study presents the use of chicken eggshells waste utilizing palm kernel shell based activated carbon（PKSAC） through the modification of their surface to enhance the adsorption capacity of H2S. Response surface methodology technique was used to optimize the process conditions and they were found to be： 500 mg/L for H2S initial concentration, 540 min for contact time and 1 g for adsorbent mass. The impacts of three arrangement factors（calcination temperature of impregnated activated carbon（IAC）, the calcium solution concentration and contact time of calcination） on the H2S removal efficiency and impregnated AC yield were investigated. Both responses IAC yield（IACY, %） and removal efficiency（RE, %） were maximized to optimize the IAC preparation conditions. The optimum preparation conditions for IACY and RE were found as follows： calcination temperature of IAC of 880 ℃, calcium solution concentration of 49.3% and calcination contact time of 57.6 min, which resulted in 35.8% of IACY and 98.2% RE. In addition, the equilibrium and kinetics of the process were investigated. The adsorbent was characterized using TGA, XRD, FTIR, SEM/EDX, and BET. The maximum monolayer adsorption capacity was found to be 543.47 mg/g. The results recommended that the composite of PKSAC and Ca O could be a useful material for H2S containing wastewater treatment.

Effects of hydrogenation temperature on room-temperature compressive properties of CMHT-treated Ti6Al4V alloy

Compression tests were performed at room temperature to investigate the effects of hydrogenation temperature on compressive properties of Ti6 Al4 V alloy treated by continuous multistep hydrogenation treatment(CMHT).Pressure-composition isotherms and micro structures were also studied.Results showed that the equilibrium hydrogen pressure increased,and the hydrogen absorption rate decreased with the increase of hydrogenation temperature.The amounts ofβphase andα"martensite increased first and then decreased when Ti6 Al4 V alloy was treated by four times CMHT with the increase of hydrogenation temperature.Hydrogenation temperature played a different role on the compressive properties of CMHT-treated Ti6 Al4 V alloy.The ultimate compression of Ti6 Al4 V alloy treated by 11 times CMHT at850℃increased by 83.3%as compared to the as-received Ti6 Al4 V alloy.The compressive properties of Ti6 Al4 V alloy were dependent on the amounts of different phases and microstructures when Ti6 Al4 V alloy was treated by CMHT at different temperatures.

Reduced defect density in microcrystalline silicon by hydrogen plasma treatment

： The effect of hydrogen plasma treatment （HPT） during the initial stage ofmicrocrystalline silicon （μc- Si） growth on the defect density of μc-Si has been investigated. Lower absorption coefficient in the 0.8-1.0 eV indicated less defect density compared to its counterpart without HPT. The infrared spectroscopy of μc-Si with HPT shows an increase in 2040 cm-1, which reveals more Si-H in the amorphous/crystalline interfaces. We ascribe the decrease of defect density to hydrogen passivation of the dangling bonds. Improved performance of μc-Si solar cell with HPT is due to the reduced defect density.

Clumped isotope analysis of lacustrine endogenic carbonates and implications for paleo-temperature reconstruction:A case study from Dali Lake

Carbonate clumped isotope(Δ47)is a new and reliable geothermometer.Endogenic carbonates in lake sediments are good archives to reconstruct lake water temperature using clumped isotope thermometry.However,applications of carbonate clumped isotope thermometry to lacustrine carbonates are still scarce because the existed organic and/or sulfur contaminants in such samples interfere with clumped isotope analysis and cause notable temperature biases.Therefore,exploring an effective way to remove contamination is a prerequisite to widely applying carbonate clumped isotope thermometry to lake sediments.By pretreating fine-grained endogenic carbonates from Dali lake sediments with hydrogen peroxide of different concentrations for different lengths of time,we conducted a series of conditional experiments to seek the optimal pretreatment condition for clumped isotope analysis.Δ47,Δ48 offset and 49 parameter were obtained from clumped isotope measurements to assess the effect of contamination removal.Results showed that untreated samples("0%-0")had a very high 49 parameter.After the treatment with hydrogen peroxide,the 49 parameter was significantly reduced while theΔ48 offset evidently increased.TheΔ47,Δ48 offset and 49 parameter of samples pretreated under different conditions showed significant variability,even though the measuredΔ47 temperatures changed within a relatively narrow range(i.e.,from 17.0±1.3 to 22.8±1.6°C).Among various treated samples,the sample"3%-8"yielded a smallerΔ48 offset and 49 parameter,and lowerΔ47 temperature of 17.0±1.3°C.Therefore,"reacting with 3%hydrogen peroxide for 8 h"was suggested to be the optimal condition for removing contaminants from lacustrine endogenic carbonates prior to clumped isotope analysis.At the time when the pretreatment condition was too intense(i.e.,H2O2 concentration>3%and/or reaction time>8 h),secondary contaminants might have been generated in the closed reaction system,whose ultimately transformed state may interfere with masses 47,48.Using the optimal pretreatment procedure,we obtained reasonableΔ47 temperature changes during the last deglaciation and found a temperature decrease of about 6°C in Northern China during the Younger Dryas period.Our study demonstrates a great potential of applying carbonate clumped isotope thermometry to lacustrine carbonates for paleo-temperature and paleo-elevation reconstructions in the future.

A full-scale integrated-bioreactor with two zones treating odours from sludge thickening tank and dewatering house： performance and microbial characteristics

A full-scale integrated-bioreactor consisting of a suspended zone and an immobilized zone was employed to treat the ordours emitted from a wastewater treatment plant. The inlet concentrations of H,S and NH3 were 1.6-38.6 mg.m-3 and 0.1 6.7 mg.m-3 respectively, while the steady-state outlet concentrations were reduced to 0-2.8mg.m - for H2S and 0-0.5mg.m for NH3. BothH2SandNH3 were eliminated effectively by the integrated-bioreactor. The removal efficiencies of H2S and NH3 differed between the two zones. Four species of microorganisms related to the degradation of H2S and NH3 were isolated. The characteristics and distributions of the microbes in the bioreactor depended on the inlet concentration of substrates and the micro-environmental conditions in the individual zones. Product analysis indicated that most of the H2S was oxidized into sulfate in the immobilized zone but was dissolved into the liquid phase in the suspended zone. A large amount of NH3 was converted into nitrate and nitrite by nitration in the suspended zone, whereas only a small amount of NH3 was transferred to the aqueous phase mainly by absorption or chemical neutralization in the immobilized zone. Different microbial populations dominated the individual zones, and the major biodegradation products varied accordingly.