Developing super-hydrophobic and corrosion-resistant coating on magnesium-lithium alloy via one-step hydrothermal processing

Formation of super-hydrophobic and corrosion-resistant coatings can provide significant corrosion protection to magnesium alloys.However,it remains a grand challenge to produce such coatings for magnesium-lithium alloys due to their high chemical reactivity.Herein,a one-step hydrothermal processing was developed using a stearic-acid-based precursor medium,which enables the hydrothermal conversion and the formation of low surface energy materials concurrently to produce the super-hydrophobic and corrosion-resistant coating.The multiscale microstructures with nanoscale stacks and microscale spheres on the surface,as well as the through-thickness stearates,lead to the super-hydrophobicity and excellent corrosion resistance of the obtained coating.

Gas Sensing Properties of ZnO Tetrapod-Like Whiskers Prepared by Hydrothermal Process

ZnO tetrapod-like whiskers were prepared through a hydrothermal process using zinc powder as raw material.Its microstructure and morphology were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD results showed that the crystal structure of as-obtained sample can be indexed to hexagonal wurtzite ZnO.TEM results revealed that the ZnO sample took on tetrapod-like whisker shape.The gas sensors were prepared with the traditional sintering process and their gas sensitivities were detected.The test results of gas sensitivity showed that the sensors based on ZnO tetrapod-like whiskers are very sensitive to dilute ethanol vapor and H_2S.The relatively high sensitivity and selectivity of these sensors made from ZnO tetrapod-like whiskers demonstrated the potential for developing a new class of selective ethanol sensors.

Room-temperature chlorine gas sensor based on CdSnO_(3) synthesized by hydrothermal process

The perovskite-structure CdSnO_(3) was obtained by calcinating CdSnO_(3)·3H_(2)O precursor at 550℃,which was synthesized by hydrothermal process at 170℃for 16 h.The phase and microstructure of the obtained CdSnO_(3) powders were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The CdSnO_(3) powders exhibit uniformly cubic structure with side length of about 100 nm.The effects of working temperature and concentration of detected gas on the gas response were studied.The selectivity of chlorine gas against other gases and response-recovery time of the sensor were also investigated.The results reveal that the CdSnO_(3) gas sensor has enhanced sensing properties to 1-10 ppm chlorine gas at room temperature;the value of gas response can reach 1338.9 to 5 ppm chlorine gas.Moreover,the sensor shows good selectivity and quick response behavior(23 s)to chlorine gas,indicating its application in detecting chlorine gas at room temperature in the future.

Dielectric properties of BNT-xBT prepared by hydrothermal process

The BNT ceramic sample might be a good replacement for PZT piezoelectric in industrial applications,especially in energy harvesting from crystal vibrations.In order to enhance the performance of BNT ceramic,the solid solution was chosen by substitution with Ba+2 at Morphtropic Phase Boundary(MPB).The BNT-xBT powders with x=1,0.07,0.06 and 0 were prepared by the hydrothermal method with average particle size(65–150 nm)at(90℃/72 h).The ceramic disc was sintered at(1150℃/4 h)and showed excellent relative density of about 96%.The results of X-ray diffraction(XRD)confirmed the MPB for x=0:06 and 0.07,while the BNT had a rhombohedral structure and BT had a tetragonal structure.The dielectric measurements showed that BNT,BNT-7BT,BNT-6BT behave as the relaxator ferroelectric and showed a strong dependence on frequency,especially in the MPB region while BT behaves as a normal ferroelectric.Both the Curie temperature and depolarization temperature decrease at the MPB region and showed strong dependency on frequency.

Rare-Element Pegmatites Rocks Rich and Li of the Aïr Massif of the Tchirozerine: Mineralogy and Chemical Composition Agadez Region-Northem Niger

The lithium potential in the Aïr massif is represented by mineral index of spodumene pegmatites and, lepidolite pegmatites. The mineral deposits of lithium occur in cluster or veins that cut the host rock or are located near the contact between the greenstone belt and granitic massif. The evidence of lithium is in the form of clusters or disseminated and stockwerk. Mineralogical characteristics show similarities between the Air Massif pegmatites and indicate the same homogenous source during the magma-generation process. The pegmatite rocks attracted the attention due to their wide exposure and composition, well appearance, and economically hosting of significant rare earth metals such as Sn and W. The mineralogical and petrographical investigations on the eight pegmatites rocks samples observed have a relative similarity, while a little difference in the shapes attributed to the ratio in the pegmatite rocks of the minerals. The occurrence of the kink band indicates the influence of the tectonic processes which affected the Aïr massif after the emplacement of late magmatic or post-magmatic pegmatites by injection into fractured rocks in the upper part of the crust. The Air Massif pegmatite has higher concentrations Li and of all trace elements except Hf and occasionally Zr, Ti, Sn and Mg of for the economic exploration.

Resistive Switching Memory of TiO2 Nanowire Networks Grown on Ti Foil by a Single Hydrothermal Method

The resistive switching characteristics of TiO_2 nanowire networks directly grown on Ti foil by a single-step hydrothermal technique are discussed in this paper. The Ti foil serves as the supply of Ti atoms for growth of the TiO_2 nanowires, making the preparation straightforward. It also acts as a bottom electrode for the device. A top Al electrode was fabricated by e-beam evaporation process. The Al/TiO_2 nanowire networks/Ti device fabricated in this way displayed a highly repeatable and electroforming-free bipolar resistive behavior with retention for more than 10~4 s and an OFF/ON ratio of approximately 70. The switching mechanism of this Al/TiO_2 nanowire networks/Ti device is suggested to arise from the migration of oxygen vacancies under applied electric field. This provides a facile way to obtain metal oxide nanowire-based Re RAM device in the future.

Novel synthesis of cerium oxide nano photocatalyst by a hydrothermal method

Crystalline cubic cerium oxide nano particles have been synthesized from cerium(Ⅲ)nitrate(Ce(NO_(3))_(3).6H2_(O))and sodium hydroxide by a hydrothermal method.The effect of three different molar ratios of the NaOH precipitating agent on structural,optical,and photo catalytic activity was investigated.The synthesized cerium oxide nano particles were characterized by X-ray diffraction(XRD),a UV-vis spectrometer,scanning electron microscope(SEM),energy-dispersive X-ray spectroscopy(EDAX),Raman spectroscopy and X-ray photo electron spectroscopy(XPS).According to the findings,hydrothermally synthesized cerium oxide NPs have a high efficiency for photocatalytic degradation of methylene blue when exposed to UV light.Environmental water pollution is the major issue of the atmosphere.To get fresh water,humans could search the resources to purify the water in simple way and degradation is the one of the methods to purify salt water.

Factors controlling the development of carbonate reservoirs of Ordovician Yingshan formation in the Gucheng area, Tarim Basin

Deep carbonate rocks are important targets for oil and gas exploration in China. In recent years, significant oil/gas discoveries have been made in the deep carbonate sequences in the Tarim, Sichuan, Ordos, and Bohai Bay basins. Despite significant oil/gas discoveries, large-scale exploration has not been conducted in the Gucheng area in the Tarim Basin. To break the bottleneck restricting the petroleum exploration in the Gucheng area, this study analyzed the factors controlling the formation of carbonate reservoirs of the Yingshan Formation in the Gucheng area in detail based on the basic geological conditions of the study area and the data from cores, thin sections, well logging, testing, and 3-D seismic survey. The inner shallow-ramp in the Gucheng area acts as the main sedimentary facies zone for the development of high-quality reservoirs. The grainstones formed in the high-energy environment of the inner shallow-ramp laid the foundation for subsequent reservoir development in the study area. The dolomitized shoal grainstones in the inner shallow-ramp have well-developed intercrystalline pores and intercrystalline dissolved pores due to later dolomitization, thus serving as high-quality reservoirs. Strike-slip faults are crucial to reservoir reformation and determine whether high production can be achieved in oil and gas exploitation in the study area. Moreover, later reformation by hydrothermal solutions also plays a constructive role in reservoir formation.

Growth mechanism and photocatalytic evaluation of flower-like ZnO microstructures prepared with SDBS assistance

Flower-like ZnO microstructures were successfully produced using a hydrothermal method employing ZnSO_(4)/(NH_(4))_(2)SO_(4) as a raw material.The effect of the operating parameters of the hydrothermal temperature, OH^(-)/Zn^(2+) molar ratio, time, and amount of dispersant on the phase structure and micromorphology of the ZnO particles were investigated.The synthesis conditions of the flower-like ZnO microstructures were: hydrothermal temperature of 160℃, OH^(-)/Zn^(2+) molar ratio of 5:1, reaction time of 4 h, and 4 mL of dispersant.The flower-like ZnO microstructures were comprised of hexagon-shaped ZnO rods arranged in a radiatively.Degradation experiments of Rhodamine B with the flower-like ZnO microstructures demonstrated a degradation efficiency of 97.6% after 4 h of exposure to sunshine, indicating excellent photocatalytic capacity.The growth mechanism of the flower-like ZnO microstructures was presented.

Gasoline Sensor Based on Flower-Like ZnO

<正>Flower-like ZnO was prepared through a hydrothermal process using zinc sulfate as raw material.The microstructure and morphology of the samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM).XRD results showed that the as-obtained sample could be indexed to hexagonal wurtzite ZnO.TEM results revealed that the ZnO sample presented flower-like shape.The gas sensors were prepared with the traditional sintering process and their gas sensitivities were detected.The gas sensitivity results showed that the sensors based on flower-like ZnO were very sensitive to dilute 90~# gasoline.The relatively high sensitivity and selectivity of these sensors made from flower-like ZnO demonstrated the potential for developing a new class of selective gasoline sensors.

Single-step Preparation of Nano-homogeneous NiO/YSZ Composite Anode for Solid Oxide Fuel Cells

Homogeneous co-precipitation and hydrothermal treatment were used to prepare nano- and highly dispersed Ni O/YSZ(yttria-stabilized zirconia) composite powders. Composite powders of size less than 100 nm were successfully prepared. This process did not require separate sintering of the YSZ and Ni O to be used as the raw materials for solid oxide fuel cells. The performance of a cell fabricated using the new powders(max.power density ~0.87 W/cm^2) was higher than that of a cell fabricated using conventional powders(max. power density ~0.73 W/cm^2). Co-precipitation and hydrothermal treatment proved to be very effective processes for reducing cell production costs as well as improving cell performance.

Applying artificial neural network to predict the viscosity of microalgae slurry in hydrothermal hydrolysis process

Estimation of the viscosity of microalgae slurry is the premise for the design of industrial reactors in microalgal biofuel production.To accurately predict the viscosity of microalgae slurry(Chlorella pyrenoidosa),an artificial neural network(ANN)model is designed in this study.In the ANN model,the mass fraction of microalgal cell,shear rate,temperature,and retention time during the hydrothermal hydrolysis process are used as the input variables,and the viscosity of microalgae slurry is obtained as the output variable.Comparisons show that the ANN model is in excellent agreement with the experimental data.The mean square error(MSE),Mean Absolute Error(MAE),and goodness of fit(R 2)are 0.725,0.484 and 0.991,respectively.The results provide a proof-of-concept for using ANN models to estimate the viscosity of microalgae slurry.In particular,the developed ANN model can accurately predict the viscosity of microalgae slurry in a hydrothermal hydrolysis process,which cannot be accurately predicted by a standard curve fitting method.

Degradation of kanamycin from production wastewater with high-concentration organic matrices by hydrothermal treatment

It is known that many kinds of fermentative antibiotics can be removed by temperatureenhanced hydrolysis from production wastewater based on their easy-to-hydrolyze characteristics.However,a few aminoglycosides are hard to hydrolyze below 100℃ because of their stability expressed by high molecular energy gap(E).Herein,removal of hard-to-hydrolyze kanamycin residue from production wastewater by hydrothermal treatment at subcritical temperatures was investigated.The results showed the reaction temperature had a significant impact on kanamycin degradation.The degradation half-life(t1/2)was shortened by 87.17-fold when the hydrothermal treatment temperature was increased from 100℃ to 180℃.The t1/2 of kanamycin in the N2 process was extended by 1.08-1.34-fold compared to that of the corresponding air process at reaction temperatures of 140-180℃,indicating that the reactions during hydrothermal treatment process mainly include oxidation and hydrolysis.However,the contribution of hydrolysis was calculated as 75%-98%,which showed hydrolysis played a major role during the process,providing possibilities for the removal of kanamycin from production wastewaters with high-concentration organic matrices.Five transformation products with lower antibacterial activity than kanamycin were identified using UPLC-QTOF-MS analysis.More importantly,hydrothermal treatment could remove 97.9%of antibacterial activity(kanamycin EQ,1,109 mg/L)from actual production wastewater with CODCr around 100,000 mg/L.Furthermore,the methane production yield in anaerobic inhibition tests could be increased about 2.3 times by adopting the hydrothermal pretreatment.Therefore,it is concluded that hydrothermal treatment as a pretreatment technology is an efficient method for removing high-concentration hard-to-hydrolyze antibiotic residues from wastewater with high-concentration organic matrices.

Hydrothermal synthesis of triangular CeCO3OH particles and photoluminescence properties

Ru/CeO_2[RC] and Ru/CeO_2/ethylene glycol(EG) [RCE] nanoparticles were produced by performing a simple hydrothermal reaction at 200℃ for 24 h and found to have two distinct morphologies. The RC nanoparticles are phase pureCeO_2; triangular highly crystallineCeCO_3OH nanoparticles are formed from the solution containing EG under the same hydrothermal reaction conditions at p H 8.5. EG plays an important role in the formation of the triangularCeCO_3OH nanoparticles. The polycrystallineCeCO_3OH nanoparticles retain their triangular structure even after calcination at 600℃in air but are transformed into a pureCeO_2 phase. The room temperature photoluminescence of the RC and RCE nanoparticles and of RCE calcined at 600℃[RCE-600] was also investigated. It was found that the high crystallinity triangular RCE-600 sample exhibits the highest photoluminescence intensity.

Science Letters:Hydrothermal production of formic and acetic acids from syringol

The production of formic and acetic acids (or salts) by hydrothermal oxidation of syringol, a model compound for lignin, was investigated using a batch reactor. Results show that the highest yields of formic and acetic acids were, respectively, 59.6% and 11.3% at the reaction condition of 0.5 mol/L NaOH, 120% H2O2 supply and 280 °C. These results will inform studies aiming to develop more environmental friendly lignin conversion processes by obtaining products beyond a CO2 end product.

Synthesis of bulk lanthanum polyphosphate and other rare earth phosphates through hydrothermal hot-pressing

Bulk samples of lanthanum polyphosphate were synthesized through a hydrothermal hot-pressing(HHP)process.In this process,pressing temperature,pressure and volume of water were varied in order to improve the density and strength of the resulting materials.The strength of the bulk samples was estimated through drilling and ultrasonic treatments.In order to improve the strength of the materials,the use of microwave irradiation was examined.Lanthanum polyphosphate formed porous bulk samples with a filling factor of approximately 70%,which was calculated from real and theoretical densities.With respect to machinable strength,a drilled hole greater than 7.0 mm in diameter was obtained on some bulk samples,and the diameter of the samples was 14 mm.The HHP process is a useful method for obtaining bulk samples of lanthanum polyphosphate.Bulk lanthanum polyphosphate containing water crumbled easily to a powder form upon ultrasonication.However,these bulk samples retained their shape upon ultrasonication,despite containing water,after exposure to microwave irradiation,and also experienced minimal weight loss.Furthermore,to study the effect of microwave heating,bulk lanthanum orthophosphate,yttrium orthophosphate and polyphosphate were also examined.

Advances in Climate Change Research 12(2021)48-65 Review

In boreal and arctic regions,forest fires exert great influences on biogeochemical processes,hydrothermal dynamics of the active layer and near-surface permafrost,and subsequent nutrient cycles.In this article,the studies on impacts of forest fires on the permafrost environment are reviewed.These studies indicate that forest fires could result in an irreversible degradation of permafrost,successions of boreal forests,rapid losses of soil carbon stock,and increased hazardous periglacial landforms.After forest fires,soil temperatures rise;active layer thickens;the release of soil carbon and nitrogen enhances,and;vegetation changes from coniferous forests to broad-leaved forests,shrublands or grasslands.It may take decades or even centuries for the fire-disturbed ecosystems and permafrost environment to return to pre-fire conditions,if ever possible.In boreal forest,the thickness of organic layer has a key influence on changes in permafrost and vegetation.In addition,climate warming,change of vegetation,shortening of fire return intervals,and extent of fire range and increasing of fire severity may all modify the change trajectory of the fire-impacted permafrost environment.However,the observations and research on the relationships and interactive mechanisms among the forest fires,vegetation,carbon cycle and permafrost under a changing climate are still inadequate for a systematic impact evaluation.Using the chronosequence approach of evaluating the temporal changes by measuring changes in the permafrost environment at different stages at various sites(possibly representing varied stages of permafrost degradation and modes),multi-source data assimilation and model predictions and simulations should be integrated with the results from long-and short-term field investigations,geophysical investigations and airborne surveys,laboratory testing and remote sensing.Future studies may enable quantitatively assess and predict the feed-back relationship and influence mechanism among organic layer,permafrost and active layer processes,vegetation and soil carbon under a warming climate at desired spatial and temporal scales.The irreversible changes in the boreal and artic forest ecosystem and their ecological and hydrothermal thresholds,such as those induced by forest fires,should be better and systematically studied.

Construction of ternary heterojunction Agl/C-MoS_(2) nanosheets with enhanced visible-light photocatalytic property and self-cleaning performance

Carbon-molybdenum disulfide(C-MoS_(2))ultrathin nanosheets were prepared by a hydrothermal process,and then Agl/C-MoS_(2) were synthesized via an/n-situ deposition method.This ternary heterojunction composite exhibited better photo-catalytic activity compared with those of one-component(pristine MoS_(2))and bicomponent(Agl/MoS_(2) and C-MoS_(2))materials for the degradation of organic dyes under the visible-light irradiation.In particular,by comparing with Agl/MoS_(2),the significant role of conductive amorphous carbon in Agl/C-MoS_(2) in enhancing the charge transfer during the photocatalytic degradation of dyes was first confirmed by photocurrent response and electrochemical impedance spectroscopy(EIS).A possible photocatalytic mechanism was proposed based on the capture experiment results.Furthermore,a straightforward and interesting way had been applied to test the recycled/newly-prepared Agl/C-MoS_(2) composite for revealing its distinctive self-cleaning performance and recyclability characteristic besides its good photocatalytic activity.This work could provide a reference for the design of other new ternary heterojunction composite materials with special structures and properties.