Coated boron layers by boronization and a real-time boron coating using an impurity powder dropper in the LHD

In the Large Helical Device(LHD),diborane(B2H6)is used as a standard boron source for boronization,which is assisted by helium glow discharges.In 2019,a new Impurity Powder Dropper(IPD)system was installed and is under evaluation as a real-time wall conditioning technique.In the LHD,which is a large-sized heliotron device,an additional helium(He)glow discharge cleaning(GDC)after boronization was operated for a reduction in hydrogen recycling from the coated boron layers.This operational time of 3 h was determined by spectroscopic data during glow discharges.A flat hydrogen profile is obtained on the top surface of the coated boron on the specimen exposed to boronization.The results suggest a reduction in hydrogen at the top surface by He-GDC.Trapped oxygen in coated boron was obtained by boronization,and the coated boron,which has boron-oxide,on the first wall by B-IPD was also shown.Considering the difference in coating areas between B2H6 boronization and B-IPD operation,it would be most effective to use the IPD and B2H6 boronization coating together for optimized wall conditioning.

Calculation and prediction of divertor detachment via impurity seeding by using one-dimensional model

Achieving the detachment of divertor can help to alleviate excessive heat load and sputtering problems on the target plates,thereby extending the lifetime of divertor components for fusion devices.In order to provide a fast but relatively reliable prediction of plasma parameters along the flux tube for future device design,a one-dimensional(1D)modeling code for the operating point of impurity seeded detached divertor is developed based on Python language,which is a fluid model based on previous work(Plasma Phys.Control.Fusion 58045013(2016)).The experimental observation of the onset of divertor detachment by neon(Ne)and argon(Ar)seeding in EAST is well reproduced by using the 1D modeling code.The comparison between the 1D modeling and two-dimensional(2D)simulation by the SOLPS-ITER code for CFETR detachment operation with Ne and Ar seeding also shows that they are in good agreement.We also predict the radiative power loss and corresponding impurity concentration requirement for achieving divertor detachment via different impurity seeding under high heating power conditions in EAST and CFETR phase II by using the 1D model.Based on the predictions,the optimized parameter space for divertor detachment operation on EAST and CFETR is also determined.Such a simple but reliable 1D model can provide a reasonable parameter input for a detailed and accurate analysis by 2D or three-dimensional(3D)modeling tools through rapid parameter scanning.

Prediction of impurity spectrum function by deep learning algorithm

By using the numerical renormalization group(NRG)method,we construct a large dataset with about one million spectral functions of the Anderson quantum impurity model.The dataset contains the density of states(DOS)of the host material,the strength of Coulomb interaction between on-site electrons(U),and the hybridization between the host material and the impurity site(Γ).The continued DOS and spectral functions are stored with Chebyshev coefficients and wavelet functions,respectively.From this dataset,we build seven different machine learning networks to predict the spectral function from the input data,DOS,U,andΓ.Three different evaluation indexes,mean absolute error(MAE),relative error(RE)and root mean square error(RMSE),are used to analyze the prediction abilities of different network models.Detailed analysis shows that,for the two kinds of widely used recurrent neural networks(RNNs),gate recurrent unit(GRU)has better performance than the long short term memory(LSTM)network.A combination of bidirectional GRU(BiGRU)and GRU has the best performance among GRU,BiGRU,LSTM,and BiLSTM.The MAE peak of BiGRU+GRU reaches 0.00037.We have also tested a one-dimensional convolutional neural network(1DCNN)with 20 hidden layers and a residual neural network(ResNet),we find that the 1DCNN has almost the same performance of the BiGRU+GRU network for the original dataset,while the robustness testing seems to be a little weak than BiGRU+GRU when we test all these models on two other independent datasets.The ResNet has the worst performance among all the seven network models.The datasets presented in this paper,including the large data set of the spectral function of Anderson quantum impurity model,are openly available at https://doi.org/10.57760/sciencedb.j00113.00192.

Gyro-Landau-fluid simulations of impurity effects on ion temperature gradient driven turbulence transport

The effects of impurities on ion temperature gradient(ITG)driven turbulence transport in tokamak core plasmas are investigated numerically via global simulations of microturbulence with carbon impurities and adiabatic electrons.The simulations use an extended fluid code(ExFC)based on a four-field gyro-Landau-fluid(GLF)model.The multispecies form of the normalized GLF equations is presented,which guarantees the self-consistent evolution of both bulk ions and impurities.With parametric profiles of the cyclone base case,well-benchmarked ExFC is employed to perform simulations focusing on different impurity density profiles.For a fixed temperature profile,it is found that the turbulent heat diffusivity of bulk ions in a quasi-steady state is usually lower than that without impurities,which is contrary to the linear and quasilinear predictions.The evolutions of the temperature gradient and heat diffusivity exhibit a fast relaxation process,indicating that the destabilization of the outwardly peaked impurity profile is a transient state response.Furthermore,the impurity effects from different profiles can obviously influence the nonlinear critical temperature gradient,which is likely to be dominated by linear effects.These results suggest that the improvement in plasma confinement could be attributed to the impurities,most likely through adjusting both heat diffusivity and the critical temperature gradient.

Leaching behaviors of iron and aluminum elements of ion-absorbed-rare-earth ore with a new impurity depressant

Ion-absorbed rare-earth ore is an important mineral resource which is widely extracted by in-situ leaching process. And such process generates a significant amount of impurities such as aluminum and iron ions in leaching solution simultaneously. The surface characteristics and interactions by infrared spectroscopy and X-ray diffraction were studied to optimize the leaching conditions. It is found that the environment-friendly depressant LG-01 can react with the impurity ions through the formation of a new complex on the surface of leaching residues. Thus, it reduces significantly the concentration of impurity ions in leaching solution and improves the leaching rate of rare-earth ore. Moreover, a leaching rate of 95.6% and an impurity removal rate of 92% have been achieved under the optimized conditions.

Microthermokinetic study of xanthate adsorption on impurity-doped galena

Six kinds of galena with different impurities were synthesized and the effects of impurities on the floatability of galena were investigated. The thermodynamic and kinetic parameters on the galena surface were measured using microcalorimetry, and the adsorption configuration and energy of butyl xanthate on the surfaces of galena with different impurities were simulated by density functional theory. Flotation experiments showed that Ag and Bi significantly promoted the recovery of galena, while Zn, Sb, Mn, and Cu reduced the recovery of the flotation. Microthermokinetic results indicated that the absolute value of xanthate adsorption heat was directly proportional to the flotation recovery of galena. Adsorption heat and reaction rate coefficients of xanthate on galena containing Ag or Bi were larger than those on pure galena, but smaller on galena containing Cu or Sb. Additionally, the relationship between the heat of unsaturated adsorption of xanthate and the adsorption energy of impurity atom on galena surface was investigated.

Effect of sulfur impurity on coke reactivity and its mechanism

Effect of sulfur impurity on coke reactivity was investigated by simulating petroleum coke with low-impurity pitch coke and impurities doping. And its mechanism was discussed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The results show that sulfur has strong catalysis on both air and CO2 reactivity of coke in the case of no other impurity interference. Its catalysis is probably realized by triggering organic sulfur→H2S→SO2→COS and elemental sulfur (Sx)→SO2 and organic sulfur→H2S→COS→Sx→C2S→COS reaction systems during coke?O2 and coke?CO2 reactions, respectively, which are partly circular with functions of increasing carbon consumption and enlarging coke specific surface area.

Density functional theory study of influence of impurity on electronic properties and reactivity of pyrite

The electronic property of pyrite supercell containing As,Se,Te,Co or Ni hetero atoms were calculated using density functional theory（DFT）,and the reactivities of pyrite with oxygen and xanthate were discussed by frontier orbital methods.The cell volume expands due to the presence of impurity.Co and Ni mainly affect the bands near Fermi levels,while As mainly affects the shallow and deep valence bands,and Se and Te mainly affect the deep valence bands.Electronic density analysis suggests that there exists a strong covalent interaction between hetero atom and its surrounding atoms.By frontier orbital calculation,it is suggested that As,Co and Ni have greater influence on the HOMO and LUMO of pyrite than Se and Te.In addition,pyrite containing As,Co or Ni is easier to oxidize by oxygen than pyrite containing Se or Te,and pyrite containing Co or Ni has greater interaction with collector.These are in agreement with the observed pyrite practice.

基于Mean Decrease Impurity改进XGBoost算法

针对XGBoost算法在处理高维数据集分类准确率和效率下降的情况,文中提出一种基于mean decrease impurity算法改进的XGBoost算法;并设计频数算法解决mean decrease impurity算法对特征重要度排名的随机性。实验结果表明,本方法预测效率以及准确率要优于未改进XGBoost算法,同时mean decrease impurity算法也优于基于方差算法。因此,文中所提出的分类方法具有更高的准确率和效率。

Modification Behavior of Trace Rare Earth on Impurity Phases in Commercial Purity Aluminum

Modifying effect and mechanism of trace rare earth on Fe(Si) rich impurity phases in commercial purity aluminum were studied with the aids of SEM, EDAX, TEM, etc. It is found that Ce rich mixed rare earth (RE) is an effective modifying agent, which makes the coarse Fe rich impurity phases transform into complex compounds of tiny, sphere/short stick form, thus improving mechanical properties of this material; its modifying mechanism is in that RE gathering in front of solid/liquid interface enters into the impurity phases, forming complex (AlFeSiRE) compounds; or is adsorbed in the impurity phases surface, impeding the growth of impurity phases; however, excessive RE will result in the increasing of RE compounds (secondary phases), and plasticity reduction of this material. Therefore, its addition amount should be less than 0 07% (mass fraction).

Effect of electric field on the spectrum and the persistent current of a quantum ring with two electrons （II） additional effect of a charged impurity

This paper studies the effect of a charged impurity together with or without an external homogeneous electric field on a quantum ring threaded by a magnetic field B and containing two electrons. The potential caused by the impurity has been plotted which is helpful to the understanding of the electronic structures inside the ring. The deep valley appearing in the potential curve is the source of localization, which affects seriously the Aharonov-Bohm oscillation （ABO） of the energy and persistent current. It also causes the fluctuation of the total orbital angular momentum L of the pair of electrons. It is found that the appearance of the impurity reduces the domain of the fractional ABO. During the increase of B, the domain of the integral ABO may appear earlier when B is even quite small. The transition from the localized states to extended states has also been studied. Furthermore, it has deduced a set of related formulae for a transformation, by which an impurity with a charge ep placed at an arbitrary point Rp is equivalent to an impurity with a revised charge ep placed at the X-axis with a revised radial distance Rp. This transformation facilitates the calculation and make the analysis of the physical result clearer.

Effect of continuous casting speed on mold surface flow and the related near-surface distribution of non-metallic inclusions

For the control of surface defects in interstitial-free(IF) steel, quantitative metallographic analyses of near-surface inclusions and surface liquid flow detection via the nail-board tipping method were conducted. The results show that, at casting speeds of 0.8 and 1.0 m/min, a thin liquid mold flux layer forms and non-uniform floating of argon bubbles occurs, inducing the entrainment and subsequent entrapment of the liquid flux; fine inclusion particles of Al_2O_3 can also aggregate at the solidification front. At higher casting speeds of 1.4 and 1.6 m/min, the liquid mold flux can be entrained and carried deeper into the liquid steel pool because of strong level fluctuations of the liquid steel and the flux. The optimal casting speed is approximately 1.2 m/min, with the most favorable surface flow status and, correspondingly, the lowest number of inclusions near the slab surface.

Prospects to the formation and control of potential dimer impurity E of pantoprazole sodium sesquihydrate

Pantoprazole sodium, a substituted benzimidazole derivative, is an irreversible proton pump inhibitor which is primarily used for the treatment of duodenal ulcers, gastric ulcers, and gastroesophageal reflux disease (GERD). The monographs of European Pharmacopoeia (Ph. Eur.) and United States Pharmacopoeia (USP) specify six impurities, viz.;impurities A, B, C, D, E and F, respectively for its active pharmaceutical ingredient (API). The identification and synthesis of all impurities except impurity E are well described in the literature;however, there is no report related to impurity E. The prospects to the formation and controlling of impurity E up to -0.03% in the synthesis of pantoprazole sodium sesquihydrate (PAN) were discussed in detail for the first time. The present work described the journey towards the successful development of an optimal preparation procedure of dimer impurity E. The most plausible mechanism involved in the formation of impurity E has been proposed.

Synthesis,isolation,identification and characterization of new process-related impurity in isoproterenol hydrochloride by HPLC,LC/ESI-MS and NMR

One unknown impurity （Imp-II） during the analysis of laboratory batches of isoproterenol hydrochloride was detected in the level ranging from 0.04% to 0.12% by high performance liquid chromatography with UV detection. The unknown impurity structure was proposed as 4-[2-（propan-2oylamino）ethyl]benzene-l,2-diol （Imp-II） using the liquid chromatography-mass spectrophotometry （LC-MS） analysis. Imp-II was isolated by semi-preparative liquid chromatography from the impurity-enriched reaction crude sample. Its proposed structure was confirmed by nuclear magnetic spectroscopy such as 1H, 13C, DEPT （1D NMR）, HSQC （2D NMR） and infrared spectroscopy （IR）, and retention time and purity with HPLC followed by the chemical synthesis. Due to less removable nature of Imp-II during the purification, the synthetic process was optimized proficiently to control the formation of Imp-II below to the limit 〈 0.12% in the course of reaction. The new chemical route was developed for the preparation of this impurity in required quantity with purity to use as reference standard. The most probable mechanism for the formation of Imp-II was discussed in details.

Investigation of impurity transport using laser blow-off technique in the HL-2A Ohmic and ECRH plasmas

Impurity transports in two neighboring discharges with and without electron cyclotron resonance heating（ECRH）are studied in the HL-2A tokamak by laser blow-off（LBO） technique.The progression of aluminium ions as the trace impurity is monitored by soft x-ray（SXR） and bolometer detector arrays with good temporal and spatial resolutions.Obvious difference in the time trace of the signal between the Ohmic and ECRH L-mode discharges is observed.Based on the numerical simulation with one-dimensional（1D） impurity transport code STRAHL,the radial profiles of impurity diffusion coefficient D and convective velocity V are obtained for each shot.The result shows that the diffusion coefficient D significantly increases throughout the plasma minor radius for the ECRH case with respect to the Ohmic case,and that the convection velocity V changes from negative（inward） for the Ohmic case to partially positive（outward） for the ECRH case.The result on HL-2A confirms the pump out effect of ECRH on impurity profile as reported on various other devices.

Pressure influence on the Stark effect of impurity states in a strained wurtzite GaN/Al_xGa_(1-x)N heterojunction

A variational method is adopted to investigate the properties of shallow impurity states near the interface in a free strained wurtzite GaN/AlxGa1-xN heterojunction under hydrostatic pressure and external electric field by using a simplified coherent potential approximation. Considering the biaxial strain due to lattice mismatch or epitaxial growth and the uniaxial strains effects, we investigated the Stark energy shift led by an external electric field for impurity states as functions of pressure as well as the impurity position, A1 component and areal electron density. The numerical result shows that the binding energy near linearly increases with pressure from 0 to 10 GPa. It is also found that the binding energy as a function of the electric field perpendicular to the interface shows an un-linear red shift or a blue shift for different impurity positions. The effect of increasing x on blue shift is more significant than that on the red shift for the impurity in the channel near the interface. The pressure influence on the Stark shift is more obvious with increase of electric field and the distance between an impurity and the interface. The increase of pressure decreases the blue shift but increases the red shift.

Development of vacuum ultraviolet spectroscopy for measuring edge impurity emission in the EAST tokamak

The dominant wavelength range of edge impurity emissions moves from the visible range to the vacuum ultraviolet(VUV)range,as heating power increasing in the Experimental Advanced Superconducting Tokamak(EAST).The measurement provided by the existing visible spectroscopies in EAST is not sufficient for impurity transport studies for high-parameters plasmas.Therefore,in this study,a VUV spectroscopy is newly developed to measure edge impurity emissions in EAST.One Seya-Namioka VUV spectrometer(McPherson 234/302)is used in the system,equipped with a concave-corrected holographic grating with groove density of 600 grooves mm-1.Impurity line emissions can be observed in the wavelength range ofλ=50-700 nm,covering VUV,near ultraviolet and visible ranges.The observed vertical range is Z=-350-350 mm.The minimum sampling time can be set to 5 ms under full vertical binning(FVB)mode.VUV spectroscopy has been used to measure the edge impurity emission for the 2019 EAST experimental campaign.Impurity spectra are identified for several impurity species,i.e.,lithium(Li),carbon(C),oxygen(O),and iron(Fe).Several candidates for tungsten(W)lines are also measured but their clear identification is very difficult due to a strong overlap with Fe lines.Time evolutions of impurity carbon emissions of CⅡat 134.5 nm and CⅢat 97.7 nm are analyzed to prove the system capability of time-resolved measurement.The measurements of the VUV spectroscopy are very helpful for edge impurity transport study in the high-parameters plasma in EAST.

Influence of Fe_2O_3 Impurity on the Crystalline Structure of Cordierite Synthesized from Waste Aluminum Slag

The influence of Fe2O3 impurity on the crystalline structure of cordierite synthesized from waste aluminum slag is discussed. XRD and SEM techniques were employed to characterize the crystalline structure and microstructure of each specimen. Philips X’pert plus software was used to determine the lattice parameters of each specimen. The results show that the Fe2O3 content of 0.8～1.6wt% is beneficial to the formation of cordierite, with the cordierite amount reaching 90wt%. So 0.8～1.6wt% is considered as the allowable Fe2O3 content in the specimens and 0.8wt% is determined to be the best after overall analysis. Plus software analysis shows that the cordierite in each specimen has the same symmetrical hexagonal structure as the single crystal, and the lattice parameters as well as the lattice dimensions change slightly.

Identification,synthesis and characterization of an unknown process related impurity in eslicarbazepine acetate active pharmaceutical ingredient by LC/ESI-IT/MS,~1H,^(13)C and ~1H-~1H COSY NMR

A new impurity was detected during high performance liquid chromatographic （HPLC） analysis of eslicarbazepine acetate active pharmaceutical ingredient. The structure of unknown impurity was postulated based on liquid chromatography mass spectrometry using electrospray ionization and ion trap analyzer （LC/ESI-IT/MS） analysis. Proposed structure of impurity was unambiguously confirmed by synthesis followed by characterization using 1H, 13C nuclear magnetic resonance spectrometry （NMR）, 1H-1H correlation spectro-scopy （COSY） and infrared spectroscopy （IR）. Based on the spectroscopic and spectrometric data, unknown impurity was characterized as 5-carbamoyl-10,11-dihydro-5H-dibenzo[b,f]azepin-10-yl propionate.

Impurity Emission Behavior in the Soft X-Ray and Extreme Ultraviolet Range on EAST

Spectroscopy in the soft X-ray and extreme ultraviolet （XEUV） region is very im- portant in magnetic fusion research. Recently, two fiat-field spectrometers that utilize a varied line spacing grating to image the spectra of 1-13 nm and 5-50 nm were installed on EAST for core impurity emission monitoring and impurity transport study. The instruments were proven to be capable of observing spectral lines from low-Z impurities （Li, C, O, N, Ar, etc.） and highly ionized medium- and high-Z impurities （Fe, Cr, Ni, Cu, Mo, etc.）. For example, spectra in the wavelength intervals of 1-2 nm and 5-13 nm contained strong metal lines~ especially molybdenum lines during H-mode phases. Argon and nitrogen lines were also observed, which were injected for diagnostic purposes. Impurity lines were identified and compared to measurements on other magnetic fusion research devices. Detailed measurements of radial emission profiles from various impurity line emissions were also presented.