Investigation of Formation Process of the Chrome-free Passivation Film of Electrodeposited Zinc

The feasibility was investigated to substitute chrome-free passivation treatment of electrodeposited zinc in a titanium bath for chromate passivation treatment. The formation mechanism of the chrome-free passivation film was further analyzed. The surface mor- phologies and the elemental compositions of the treated samples with varied immersion times were observed by scanning electron mi- croscopy （SEM） and determined by energy dispersion spectrometry （EDS）, respectively. The electrode potential of the sample surface was recorded in the film formation process. The changes of the electrode potential are in accordance with that of SEM and EDS of the sample surface. The results of X-ray photoelectron spectroscopy （XPS） show the chrome-free passivation film composed ofZnO, SiO2, TiO2, Zn4Si207（OH）2, and SrF2. The anode zinc dissolution and the local pH value increase due to the cathode hydrogen ion reduction process result in the formation of the chrome-free passivation film. The macro-images of the chrome-free passivation films formed on electrodeposited zinc show that the color of the film changes from blue to iridescence with the increase of the immersion times.

Evaluation on the natural gas hydrate formation process

Gas hydrates have endowed with great potential in gas storage,and rapid formation of gas hydrates is critical to use this novel technology.This work evaluated the natural gas hydrate formation process,which was compared from six parameters,including conversion of water to hydrate,storage capacity,the rate of hydrate formation,space velocity(SV)of hydrate reaction,energy consumption and hydrate removal.The literature was selected by analyzing and comparing these six parameters mentioned above,meanwhile placing emphasis on the three parameters of storage capacity,the rate of hydrate formation and space velocity of hydrate reaction.Through analysis and comparison,four conclusions could be obtained as follows.Firstly,the overall performance of the stirring process and the spraying process were better than other processes after analyzing the six parameters.Secondly,the additive types,the reactor structure and the reactor size had influence on the natural gas hydrate formation process.Thirdly,the energy consumption via reciprocating impact in the hydrate formation process was higher than that via stirring,spraying and static higee.Finally,it was one key for hydrate removal to realize the hydrate industrial production.

Formation Process of Magnetized Fusion Target on the YingGuang 1 Device

Magnetized target fusion is an alternative method to fulfill the goal of controlled fusion, which combines advan- tages of both magnetic confinement fusion and inertial confinement fusion since its parameter space lies between the two traditional ways. Field reversed configuration （FFtC） is a good candidate of magnetized targets due to its translatable, compressible, high /3 and high energy density properties. Dynamic formation process of high density FFtC is observed on the YingGuang 1 device for the first time in China. The evolution of a magnetic field is detected with magnetic probes, and the compression process can be clearly seen from images taken with a high-speed multi-frame CCD camera. The process is also studied with two-dimensional magneto hydrodynamic code MPF-2D theoretically, and the results agree well with the experiment. Combining the experimental data and the theoretical analysis, the length of the formed FRC is about 39 cm, the diameter is about 2-2. 7cm, the average density is 1.3× 1016 cm-3, and the average temperature is 137eV.

AN IMPROVED NONADIABATIC COLLISION MODEL FOR ION-PIR FORMATION PROCESS:A+BC→A^++BC^- Zheng Ting CAI and Yu Guang MU

Hickman's fast nonadiabatic collision model for the ion-pair formation reaction A+BC→A^++BC^- was improved,where the classical trajectory has been represented by solution of motion equation UR=-dV(R)/dR, here V(R)is Morse potential.Employing this model to the CS+O_2→CS^++O_2^-reaction,a satisfactory agreement with experimental data has been obtained.

A synchronous nucleation and passivation strategy for controllable synthesis of Au36(PA)24: unveiling the formation process and the role of Au22(PA)18 intermediate

Despite the recent progress on controllable synthesis of alkynyl-protected Au nanoclusters,the effective synthetic means are very limited and the cluster formation process still remains puzzling.Here,we develop a novel synchronous nucleation and passivation strategy to fabricate Au36(PA)24(PA=phenylacetylenyl) nanoclusters with high yield.In Au36(PA)24formation process,Au22(PA)18as key intermediate was identified.Meanwhile,Au22(PA)18can be synthesized under a low amount of reductant,and by employing more reductants,Au22(PA)18can turn into Au36(PA)24eventually.Moreover,the structure evolution from Au22(PA)18to Au36(PA)24is proposed,where four Au13cuboctahedra can yield one Au28kernel.Finally,the ratiocination is verified by the good accordance between the predicted intermediate/product ratio and the experimental value.This study not only offers a novel synthetic strategy,but also sheds light on understanding the structural evolution process of alkynyl-protected Au nanoclusters at atomic level.

Formation of Low-Level Jets over Southern China in the Mei-yu Season

This study examines the diversity of low-level jet(LLJ)formation and related physical processes over southern China.A total of 171 LLJ formation events with enhanced daily southwesterlies and early-morning maximum wind speeds were observed during the mei-yu seasons of 1989–2018.The LLJs can be further categorized into four types based on the increases in the daily mean and diurnal amplitude of the low-level winds.Analysis of the synoptic-scale disturbances shows that the two types of LLJ formation(Q1 and Q4),which feature large increases of daily southerly wind components,are mainly induced by west-east dipole patterns of pressure change,in association with the enhanced southwest vortex and/or the western Pacific subtropical high(WPSH).In contrast,the other two types(Q2 and Q3),which feature relatively large increases in their daily westerly components,are related to a northwest-southeast dipole pattern of pressure change due to the mid-latitude trough and the WPSH.We further analyze the considerable variations in the diurnal thermal forcing among the LLJ formation events.The strong(weak)daytime heating of solar radiation leads to relatively large(small)increases in the diurnal amplitude of low-level winds in Q1 and Q2(Q3 and Q4)types.Therefore,different combinations of synopticscale disturbances and diurnal thermal forcings are found to account for the diversity in LLJ formation and associated differences in downstream rainfall patterns.These results help to improve our understanding and prediction of the formation of LLJs.

VISUAL OBSERBATION OF HCFC141b GAS HYDRATE FORMATION/DECOMPOSITION PROCESS OUTSIDE OF A TUBE

In order to design a kind of heat exchanger suitable to the indirect-touched gas hydrate cool storage vessel, a visual observation of HCFC141b gas hydrate formation/decomposition process was presented through a self-designed small-scale visualization apparatus of gas hydrate cool storage. Based on the shooted photos and recorded temperatures, the formation/decomposition process of HCFC141b are described, some characteristics are concluded, and some suggestions of designing heat exchanger are indicated according to the specific characteristics of HCFC141b gas hydrate formation/decomposition process.

Water transfer characteristics during methane hydrate formation and dissociation processes inside saturated sand

Gas hydrates formation and dissociation processes inside porous media are always accompanied by water transfer behavior, which is similar to the water behavior of ice freezing and thawing processes. These processes have been studied by many researchers, but all the studies are so far on the water transfer characteristics outside porous media and the water transfer characteristics inside porous media have been little known. In this study, in order to study the water transfer characteristics inside porous media during methane hydrate formation and dissociation processes, a novel apparatus with three pF-meter sensors which can detect water content changes inside porous media was applied. It was experimentally observed that methane hydrate formation processes were accompanied by water transfer from bottom to top inside porous media, however, the water behavior during hydrate dissociation processes was abnormal, for which more studies are needed to find out the real reason in our future work.

Simulations of THM processes in buffer-rock barriers of high-level waste disposal in an argillaceous formation

The main objective of this paper is to investigate and analyse the thermo-hydro-mechanical（THM） coupling phenomena and their influences on the repository safety.In this paper,the high-level waste（HLW） disposal concept in drifts in clay formation with backfilled bentonite buffer is represented numerically using the CODE BRIGHT developed by the Technical University of Catalonia in Barcelona.The parameters of clay and bentonite used in the simulation are determined by laboratory and in situ experiments.The calculation results are presented to show the hydro-mechanical（HM） processes during the operation phase and the THM processes in the after-closure phase.According to the simulation results,the most probable critical processes for the disposal project have been represented and analyzed.The work also provides an input for additional development regarding the design,assessment and validation of the HLW disposal concept.

Effect of Nonlinear Dynamic Process on Formation and Breakdown of Blocking

With the L-P approximate method(variation of parameter method), a barotropic channel model in β-plane is used to study the effect of nonlinear interaction between two waves with different scales on the formation of blocking. The approximate analytical solution, which can describe the process of the blocking formation, maintenance and breakdown, has been obtained by using the method of aproximate expansion. The importance of nonlinear interaction between two waves with different scales is stressed in the solution. The result suggests that the nonlinear interaction is the main dynamic process of the blocking formation. Some required conditions of blocking formation are also discussed.

Formation and reactivation mechanisms of large-scale ancient landslides in the Longwu River basin in the northeast Tibetan Plateau, China

The northeastern Tibetan Plateau exhibits steep topography and strong internal or external dynamic geological effect and is frequently subjected to strong earthquakes and heavy rainfall. The geological evolution has resulted in a wide distribution of ancient landslides, which has become a hotspot for studying ancient landslide formation and reactivation. In recent decades, several ancient landslides on both banks of the Longwu River, Qinghai Province, China were reactivated, causing serious economic losses and casualties. This study conducted remote sensing interpretation and ground surveys on these ancient landslides. Totally 59 ancient landslides were identified, and the formation mechanism, evolution process, and resurrection mechanism of the Longwu Xishan No.2 ancient landslide were analyzed by means of a detailed field geological survey, drilling, and series of experimental tests such as the particle size distribution test, the Xray diffraction test and the mechanical properties test. The results show that the formation of these ancient landslides is closely associated with the uplift of the Tibetan Plateau and the erosion of the Longwu River. Firstly, the intermittent uplift of the Tibetan Plateau lead to the diversion and downcutting of the Longwu River basin, which forms the alternate slope topography with steep and slow slopes, thereby providing favourable topography and slope structure conditions for the formation of landslides. Secondly, 34.5% clay-mineral content in the Neoproterozoic mudstone with 32.7% particle size less than 0.005 mm, and the corrosion and softening effects of the Neogene mudstone with high clay mineral content under the erosion of water provides favourable material conditions for the formation of landslides. Thirdly, rainfall and human activities are the primary triggering factors for the revival of this ancient landslide group. It is revealed that the evolution process of the ancient landslides on both banks of the Longwu River can be divided into five stages namely tectonic rapid uplift slope formation, river erosion creep-sliding deformation, slope instability critical status, landslide failure-movement-accumulation, and slope reactivation under rainfall erosion and engineering excavation.

Methane hydrate formation comparisons in media with and without a water source supply

Water is a necessary element during gas hydrate formations. Therefore, by analyzing water depletion changes in media, the reaction characteristics of methane hydrate in media can be studied. In this study, two water sources supplying some liquid water which may be consumed by the methane hydrate formation reactions were designed and assembled. Using them, the full formation processes of methane hydrate was studied. Experimental results show the following： If heat released from nucleation reaction of methane hydrate is diffused rapidly, the nucleation ratios will be enhanced discernibly. While the hydrate is formed, a force is generated that sucks fresh water from the source into the vicinity of the hydrate, slowing down the cementation process and causing some hydrate grain dissociation. As a result of cementation differences, the hydrate reaction processes with different water sources present linear or quadratic equation characteristics. After a few repeated dissociation and formation processes of some hydrate grains caused by the fresh water, the gas amounts contained in hydrate will be significantly enhanced.

Influences of burial process on diagenesis and high-quality reservoir development of deep-ultra-deep clastic rocks:A case study of Lower Cretaceous Qingshuihe Formation in southern margin of Junggar Basin,NW China

Taking the Lower Cretaceous Qingshuihe Formation in the southern margin of Junggar Basin as an example,the influences of the burial process in a foreland basin on the diagenesis and the development of high-quality reservoirs of deep and ultra-deep clastic rocks were investigated using thin section,scanning electron microscope,electron probe,stable isotopic composition and fluid inclusion data.The Qingshuihe Formation went through four burial stages of slow shallow burial,tectonic uplift,progressive deep burial and rapid deep burial successively.The stages of slow shallow burial and tectonic uplift not only can alleviate the mechanical compaction of grains,but also can maintain an open diagenetic system in the reservoirs for a long time,which promotes the dissolution of soluble components by meteoric freshwater and inhibits the precipitation of dissolution products in the reservoirs.The late rapid deep burial process contributed to the development of fluid overpressure,which effectively inhibits the destruction of primary pores by compaction and cementation.The fluid overpressure promotes the development of microfractures in the reservoir,which enhances the dissolution effect of organic acids.Based on the quantitative reconstruction of porosity evolution history,it is found that the long-term slow shallow burial and tectonic uplift processes make the greatest contribution to the development of deep-ultra-deep high-quality clastic rock reservoirs,followed by the late rapid deep burial process,and the progressive deep burial process has little contribution.

δ18O,δD and d-excess signatures of ground ice in permafrost in the Beiluhe Basin on the Qinghai-Tibet Plateau,China

In this paper, stable isotope （δ18O, δD） investigations were completed in ground ice from a deep borehole in the Beiluhe Basin on northern Qinghai-Tibet Plateau to unravel the isotopic variations of ground ice and their possible source water. The δ18O and δD of ground ice show distinctive characteristics compared with precipitation and surface water. The near-surface ground ice is highly enriched in heavier isotopes （δ18O and δD）, which were gradually depleted from top to bottom along the profile. It is suggestive of different origin and ice formation process. According to isotopic variations, the ice profile was divided into three sections： the near-surface ground ice at 2.5 m is frozen by the active-layer water which suffered evaporation. It is possible that ground ice between 3 and 4.2 m is recharged by the infiltration of snowmelt. From 5 to 6 m, the ground ice show complex origin and formation processes. Isotopic variations from 6 to 11.1 m and 20.55 m indicate different replenishment water. The calculated slope of freezing line （S=6.4） is larger than the experimental value （5.76）, and is suggestive of complex origin and formation process of ground ice.

A small electron beam ion trap/source facility for electron/neutral-ion collisional spectroscopy in astrophysical plasmas

Spectra are fundamental observation data used for astronomical research,but understanding them strongly depends on theoretical models with many fundamental parameters from theoretical calculations.Different models give different insights for understanding a specific object.Hence,laboratory benchmarks for these theoretical models become necessary.An electron beam ion trap is an ideal facility for spectroscopic benchmarks due to its similar conditions of electron density and temperature compared to astrophysical plasmas in stellar coronae,supernova remnants and so on.In this paper,we will describe the performance of a small electron beam ion trap/source facility installed at National Astronomical Observatories,Chinese Academy of Sciences.We present some preliminary experimental results on X-ray emission,ion production,the ionization process of trapped ions as well as the effects of charge exchange on the ionization.

Preparation of Fe_(3)Si and FeSi intermetallic compounds from copper slag by electrochemical method

Fe_(3)Si and FeSi intermetallic compounds were prepared by CaCl_(2)-NaCl melt electrolysis at 800℃from the non-magnetic copper slag compound.The phase transition of the cathode particles with different electrolysis voltages and durations was investigated by X-ray fluorescence spectroscopy,inductively coupled plasma spectroscopy,X-ray diffraction,and scanning electron microscopy.The results showed that Fe_(3)Si and FeSi intermetallic compounds can be obtained by one-step electrolysis for 10 h at 3.2 V and two-step electrolysis of 2.5 V for 4 h and 3.2 V for 6 h.However,the current efficiency increased from 31.70%of one-step electrolysis to 39.87%of two-step electrolysis.The formation of Fe_(3)Si and FeSi intermetallic compounds is a gradual evolution process with the increase in Si content,following the formation law of Fe→FeSi→Fe_(3)Si+FeSi→FeSi.The metallic impurities of the final product were 1.29 wt.%Mg and 3.85 wt.%Al,respectively.

Enabling the thermal stability of solid electrolyte interphase in Li-ion battery

Lithium-ion batteries(LIBs)provide power for a variety of applications from the portable electronics to electric vehicles,and now they are supporting the smart grid.Safety of LIBs is of paramount importance in these scenarios.Specifically,thermal safety arouses increasing attention with the piling-up of LIBs.Heat generation can be significant.Hazardous incidents happen when thermal runaway occurs in a single cell level and drives the battery pack failure.Moreover,thermal runaway of LIBs is believed to originate from the exothermic reactions starting from the breakdown of the solid/cathode electrolyte interphase(SEI/CEI).To mitigate this challenge for a safe operation of LIBs,one straightforward and low-cost method is to build thermally stable SEI/CEI.This review gives an overview on the thermal behaviors of SEI/CEI as the first step in thermal runaway.We analyzed the electrolyte composition and the formation process of SEI/CEI that enable SEI/CEI of high thermal stability.It is identified that the stable lithium salts coupled with solvents of high boiling point is one way to enhance thermal stability of the battery system.In addition,the unsaturated bonds,halogen,phosphorus,sulfur,phenol,organic borate,borane,and silane are functional components to facilitate the formation of a thermally stable SEI/CEI,which is the immediate solution to boost thermal stability of high capacity electrodes.Moreover,in-situ polymerization/solidification is effective in enhancing simultaneously the electrochemical,chemical,and thermal stability.Finally,we revealed that only by constructing a stable SEI/CEI simultaneously could we harvest a battery system of high thermal stability.

Preparation and Characterization of Flower-like Cu_2SnS_3 Nanostructures by Solvothermal Route

Flower-like Cu2SnS3 nanostructures composed of nano-flakes were successfully synthesized by solvothermal technique at 180 ℃ for 16 h. In the preparation process, CuCl2·H2O, SnCl2·2H2O and thiourea were used as raw materials, and ethylene glycol were used as solvent. The results showed that the obtained product was pure phase Cu2SnS3. The average diameter of Cu2SnS3 flowers and the thickness of the nano-flakes were about 1-1.5 μm and 10 nm, respectively. The influence of reaction time and solvents on the morphology, size and structure of the products was investigated by powder X-ray diffraction and field-emission scan electron microscopy （FESEM）. The ultraviolet-visible absorption spectrum measurement indicated that the band gap of the sample was about 1.26 eV and could be applied to the absorbing layer of thin solar cell. The possible formation mechanism of flower-like Cu2SnS3 was also proposed and discussed.