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In order to study the effect of Pt on bond coat in thermal barrier coating, the corresponding Pt modified Ni3Al-base alloys were fabricated using arc melting. The microstructure and the oxidation behavior of the Ni–25Al–xPt (x = 0, 10, 20 and 30 at %) alloys at 1100°C were characterized using X-ray diffraction, scanning and transmission electron microscopy. The experimental results showed that the Ni–25Al–xPt alloys kept a single γ′-Ni3Al phase structure when Pt content up to 20 at %, while Ni–25Al–30Pt alloy consisted of two-phase structures of γ-Ni and γ′-Ni3Al, which may be caused by the phase deviation resulting from the volatilization loss of Al. Isothermal oxidation test indicated that the addition of Pt in Ni3Al-base alloys promoted Al2O3 scale formation, affected the oxidation surface morphology, reduced oxidation weight gain and the thickness of the oxide layer. [ABSTRACT FROM AUTHOR]

The hot tail generation is expected to be the dominant mechanism for the runaway electron (RE) seed formation during disruptions, especially in large devices with high electron temperature such as international thermonuclear experimental reactor. This issue has been studied in the HL-2A tokamak by using the superthermal electrons produced by lower hybrid waves (LHWs), which can adjust the hot tail distribution. It was observed that RE generation was significantly enhanced during disruptions with LHWs. The measurements show that the multitudinous superthermal electrons with energy of 40–60 keV created by LHWs greatly transform the landscape of hot tail distribution. The tail electrons can be directly converted into REs under the acceleration of the high toroidal electric field during disruptions. Runaway current plateaus are more likely to be formed than in normal disruptions without LHWs. However, some abnormal phenomena have also been observed, that is, RE generation was not enhanced and no runaway current plateau was formed during some disruptions with LHWs. It is found that this is attributed to the complete loss of RE seeds caused by strong magnetic fluctuations, which prevents the generation of REs during disruptions. This may provide a way to avoid the generation of REs during disruptions by actively exciting magnetic fluctuations. [ABSTRACT FROM AUTHOR]

A multi-machine study has been carried out to investigate the impact of a strongly bounded wave propagation domain on the Lower Hybrid current drive, a condition which occurs principally in high aspect ratio tokamaks. In this regime, the condition of kinetic resonance can be far above the upper boundary of the propagation domain, and may not be achieved by the usual toroidal upshift. Therefore no tail of fast electrons can be pulled out from the thermal bulk. Nevertheless, while tokamak plasmas are in principle almost transparent to the wave in this regime so-called "unbridgeable spectral gap", full current drive is well achieved for the two tokamaks considered in this study, TRIAM-1M (Zushi et al. Nucl Fusion 43:1600, 2003) and WEST (Bourdelle et al. Nucl Fusion 55:063017, 2015), both characterized by a very large aspect ratio R / a > 5.5 . The case of the high aspect ratio tokamak HL-2A (Liu et al. Nucl Fusion 45:S239, 2005) for which the wave propagation domain has also an upper boundary, but close to the resonance condition, is considered by comparison. First principles modeling of the rf-driven current and the fast electron bremsstrahlung using the ALOHA/C3PO/LUKE/R5-X2 chain of codes shows unambiguously that the spectral gap must be already filled at the separatrix in order to reproduce quantitatively observations and some important parametric dependencies. This result is an important milestone in the physics understanding of the Lower Hybrid current drive, highlighting the existence of a powerful and likely universal alternative mechanism to bridge the spectral gap, that is not related to toroidal magnetic refraction. With an initially broad power spectrum, lobes with low parallel refractive indexes that carry most of the plasma current can be absorbed in almost single pass, restoring the full validity of the ray-tracing approximation for describing the propagation of the Lower Hybrid wave in cold plasmas. [ABSTRACT FROM AUTHOR]

Edge localized mode (ELM) mitigation with lower hybrid current drive (LHCD) has been observed in the HL-2A tokamak. This mitigation effect is very sensitive to the parameters as the plasma density and the LHCD absorbed power, i.e., more easily to be observed for high density and large LHCD absorbed power. The divertor peak heat load released by ELM has been significantly reduced during the mitigation phase. The pedestal density gradient is slightly reduced during ELM mitigation, and the plasma rotation velocity and ion temperature are significantly reduced by LHCD. It has been found that the ELM mitigation is not synchronized with the LHCD, while it is synchronized with the increase of the pedestal turbulence, showing that the enhancement of the transport due to the pedestal turbulence can be the direct cause of the ELM mitigation. [ABSTRACT FROM AUTHOR]

In HL-2A and J-TEXT ohmic confinement regimes, an electrostatic turbulence with quasi-coherent characteristics in spectra of density fluctuations was observed by multi-channel microwave reflectometers. These quasi-coherent modes (QCMs) were detectable in a large plasma region (r/a ~ 0.3-0.8). The characteristic frequencies of QCMs were in the range of 30-140 kHz. The mode is rotated in the electron diamagnetic direction. In the plasmas with QCMs, trapped electron mode (TEM) was predicted to be unstable by gyrokinetic simulations. The combined experimental results show that the TEM is survived in the linear ohmic confinement regime of plasmas. The quasi-coherent TEM was replaced by broad-band fluctuations when the plasma transits from linear to saturated ohmic confinement regime. The observation was strongly related to the turbulence transition from TEM to ion temperature gradient mode. A critical gradient threshold for TEM excitation in electron temperature gradient was directly found. The effect of TEM on density profile peaking was presented. [ABSTRACT FROM AUTHOR]

Interactions among pedestal shear flows, turbulence, and the formation of the edge transport barrier have been studied in H-mode plasmas of the HL-2A tokamak by multi-channel Doppler reflectometry with high spatiotemporal resolution. Geodesic acoustic mode (GAM) has been observed during the L-I-H transition. It has been observed that the plasma transits into the I-phase when the mean E × B shear flow reaches a critical value. The bi-spectrum analysis has shown that there is a strong interaction between GAM and limit cycle oscillation (LCO), and the energy transfer is from GAM to LCO, suggesting that GAM can assist the L-I transition. The regulation of the edge turbulence by LCOs helps to build the steep pedestal and initialize the confinement improvement of the plasma. It has been found that the mean E × B shear flow is further increased just before the I-H transition, accompanied by the turbulence suppression, leading to the edge transport reduction and the pedestal formation. It has been demonstrated that the increase of the mean E × B shear flow prior to the L-I and I-H transitions is due to the ion diamagnetic component of E r . These results corroborate that the mean E × B shear flow plays a key role in the L-I and I-H transitions. [ABSTRACT FROM AUTHOR]

The impact of impurity ions on a pedestal has been investigated in the HL-2A Tokamak, at the Southwestern Institute of Physics, Chengdu, China. Experimental results have clearly shown that during the H-mode phase, an electromagnetic turbulence was excited in the edge plasma region, where the impurity ions exhibited a peaked profile. It has been found that double impurity critical gradients are responsible for triggering the turbulence. Strong stiffness of the impurity profile has been observed during cyclic transitions between the I-phase and H-mode regime. The results suggest that the underlying physics of the self-regulated edge impurity profile offers the possibility for an active control of the pedestal dynamics via pedestal turbulence. [ABSTRACT FROM AUTHOR]

A critical challenge facing the basic long-pulse high-confinement operation scenario (H mode) for ITER is to control a magnetohydrodynamic (MHD) instability, known as the edge localized mode (ELM), which leads to cyclical high peak heat and particle fluxes at the plasma facing components. A breakthrough is made in the Experimental Advanced Superconducting Tokamak in achieving a new steady-state H mode without the presence of ELMs for a duration exceeding hundreds of energy confinement times, by using a novel technique of continuous real-time injection of a lithium (Li) aerosol into the edge plasma. The steady-state ELM-free H mode is accompanied by a strong edge coherent MHD mode (ECM) at a frequency of 35-40 kHz with a poloidal wavelength of 10.2 cm in the ion diamagnetic drift direction, providing continuous heat and particle exhaust, thus preventing the transient heat deposition on plasma facing components and impurity accumulation in the confined plasma. It is truly remarkable that Li injection appears to promote the growth of the ECM, owing to the increase in Li concentration and hence collisionality at the edge, as predicted by GYRO simulations. This new steady-state ELM-free H-mode regime, enabled by real-time Li injection, may open a new avenue for next-step fusion development. [ABSTRACT FROM AUTHOR]

A correction to the article "New Steady-State Quiescent High-Confinement Plasma in an Experimental Advanced Superconducting Tokamak" that was published in the 2015 issue is presented.

High-β_{θe} (a ratio of the electron thermal pressure to the poloidal magnetic pressure) steady-state long-pulse plasmas with steep central electron temperature gradient are achieved in the Experimental Advanced Superconducting Tokamak. An intrinsic current is observed to be modulated by turbulence driven by the electron temperature gradient. This turbulent current is generated in the countercurrent direction and can reach a maximum ratio of 25% of the bootstrap current. Gyrokinetic simulations and experimental observations indicate that the turbulence is the electron temperature gradient mode (ETG). The dominant mechanism for the turbulent current generation is due to the divergence of ETG-driven residual flux of current. Good agreement has been found between experiments and theory for the critical value of the electron temperature gradient triggering ETG and for the level of the turbulent current. The maximum values of turbulent current and electron temperature gradient lead to the destabilization of an m/n=1/1 kink mode, which by counteraction reduces the turbulence level (m and n are the poloidal and toroidal mode number, respectively). These observations suggest that the self-regulation system including turbulence, turbulent current, and kink mode is a contributing mechanism for sustaining the steady-state long-pulse high-β_{θe} regime.

Perturbative particle transport experiment has been performed in the HL-2A tokamak by using supersonic molecular beam injection (SMBI) as an external particle source. The spatiotemporal evolution of edge density perturbation is traced and the particle source and the flux-gradient relation are obtained experimentally. The flux-gradient relation is found to be far from the diffusive model and three different transport processes are revealed, including pinch-dominant process, diffusion-pinch process and intermittent decays., (© 2020 The Authors.)

In February 2018, one 54-year-old male patient with severe scald complicated with pneumonia and sepsis was transferred to Qingdao Municipal Hospital from other hospital. Drugs including cephalosporin, vancomycin, and imipenem/cilastatin combined with ciprofloxacin were used successively for anti-infective treatment, with no obvious effect. Multiple bacterial culture results of sputum, blood, and wound exudate showed infection of extensively drug resistant Pseudomonas aeruginosa . On the 4th day of admission, the anti-infective treatment plan was adjusted, and plasma, red blood cell, and albumin were supplemented and nutritional support and symptomatic treatment were performed. At the same time, medication and drug-related adverse reaction were monitored. After treatment for more than 10 days, infection of the patient was effectively controlled and the condition gradually improved. The case suggests that severely burned patients are prone to have serious and fatal systemic infection, irregular use of antibiotics increases the risk of infection of extensively drug resistant bacteria, clear anti-infection idea and effective application of antibacterial drug can help to improve the success rate of infection treatment and are of important value in improving the prognosis of patients with severe burn.

Objective: To study the clinical management way for HPV(+)/papanicolaou (Pap)(-) during cervical cancer screening. Methods: To analyze retrospectively the data from the patients who had loop electrical excision procedure (LEEP) for biopsy confirmed cervical intraepithelial neoplasia (CIN) Ⅱ in Peking University People's Hospital from Jan. 2010 to Dec. 2014. Results: (1) For biopsy confirmed CIN Ⅱ, HPV positive rate was 98.5% (135/137), Pap test positive [≥atypical squamous cell of undetermined significance (ASCUS)] rate was 69.3% (95/137), there was significant difference between them (χ(2)=43.32, P< 0.01). (2) For the 42 patients with HPV(+)/Pap(-), whose cytology slides were reviewed again. Among them, the interpretations of there were 16 cases confirmed as the same before, while 26 cases were changed to abnormal (≥ASCUS). Cytology be misdiagnosed was 19.0% (26/137) at the first review. Among the 26 cases, 13 (50.0%) cases were missed for the little amount of abnormal cells, 8 (30.8%) cases for mild atypical morphology changed; the other 5 (19.2%) cases missed for stain problems. (3) For the cervical LEEP samples, 37 cases of the pathology diagnosis were upgrade to CIN Ⅲ(+), among them, 2 cases of microinvasive cervical carcinoma, 1 case of invasive cancer, 34 cases of CIN Ⅲ; 37 cases were CINⅠ or no lesion found; 63 cases were still CIN Ⅱ. Four to six months later after LEEP, the cytology abnormal rate was 11.7% (16/137), and the HR-HPV positive rate was 34.3% (47/137). Conclusions: Compared with cytology alone, cytology combined with HPV testing increase the sensitivity of cervical high grade lesion. For the cases of HPV(+)/Pap(-) cases, the cytology slides should be reviewed. The quality control of cervical exfoliate sample collection and interpretation should be strengthened. LEEP procedure is not only a treatment method, but also it could provide samples to confirm the diagnosis.