[en] Objectives: To evaluate the clinical efficacy of immunotherapy combined with chemotherapy in patients with advanced gastric cancer and its effect on nutritional status and changes of peripheral blood T lymphocyte subsets. Methods: Sixty patients with locally advanced gastric cancer who were admitted by Affiliated Hospital of Hebei University from March 2020 to February 2021 were enrolled and randomly divided into two groups, with 30 cases in each group. The control group was treated with FOLFOX4 chemotherapy, while the experimental group was additively treated with cindilizumab on the basis of control group. The incidence of adverse reactions, clinical efficacy, improvement of nutritional and physical status, and changes in the levels of T lymphocyte subgroups in the two groups were compared and analyzed. Results: The total effective rate was 70% in the experimental group, which was better than 43.3% of the control group (p=0.04). The improvement rate of performance status (ECOG) score and nutritional indicators in the experimental group was significantly better than that in the control group (p<0.05). Moreover, the indicators of CD3+, CD4+, CD4+/CD8+ in the experimental group were significantly higher than those in the control group after treatment, with statistically significant differences (CD3+, p=0.01; CD4 +, p=0.02; CD4+/CD8+, p=0.01). Conclusion: Immunotherapy combined with chemotherapy has a significant effect on locally advanced gastric cancer patients, with significant improvement in physical strength and nutritional status, significant improvement in T lymphocyte function, and no obvious adverse reactions. It is worth promoting in clinical application. (author)

[en] Increasing the plasma density is one of the key methods in achieving an efficient fusion reaction. High-density operation is one of the hot topics in tokamak plasmas. Density limit disruptions remain an important issue for safe operation. An effective density limit disruption prediction and avoidance system is the key to avoid density limit disruptions for long pulse steady state operations. An artificial neural network has been developed for the prediction of density limit disruptions on the J-TEXT tokamak. The neural network has been improved from a simple multi-layer design to a hybrid two-stage structure. The first stage is a custom network which uses time series diagnostics as inputs to predict plasma density, and the second stage is a three-layer feedforward neural network to predict the probability of density limit disruptions. It is found that hybrid neural network structure, combined with radiation profile information as an input can significantly improve the prediction performance, especially the average warning time ($T_{\mathrm{w}\mathrm{a}\mathrm{r}\mathrm{n}}$). In particular, the $T_{\mathrm{w}\mathrm{a}\mathrm{r}\mathrm{n}}$ is eight times better than that in previous work (Wang et al 2016 Plasma Phys. Control. Fusion 58 055014) (from 5 ms to 40 ms). The success rate for density limit disruptive shots is above 90%, while, the false alarm rate for other shots is below 10%. Based on the density limit disruption prediction system and the real-time density feedback control system, the on-line density limit disruption avoidance system has been implemented on the J-TEXT tokamak. (paper)

[en] Locked modes (LMs) will be one of the major causes of disruptions in the ITER tokamak. Disruption mitigation systems (DMSs), such as massive gas injection (MGI) or shattered pellet injection (SPI), are expected to be deployed in pre-disruption discharges with large pre-existing locked modes. A series of target plasmas with an m/n  =  2/1 locked mode induced by resonant magnetic perturbation (RMP) penetration was terminated by an MGI on the J-TEXT tokamak. The penetration of the injected impurities during the process was diagnosed using a fast frame visible camera and a multi-channel polarimeter-interferometer (POLARIS) in combination. The electron temperature evolution during thermal quench (TQ) is also shown in detail. It is found that both the phase and width of the 2/1 mode have an effect on MGI shutdown dynamics. When the mode is larger than the critical width, the penetration depth and assimilation of impurities can be enhanced during pre-TQ, leading to a faster quenching process if the relative phase between the O-point of the 2/1 mode and the MGI valve is   +90°. Conversely, the penetration depth and assimilation of impurities are suppressed, leading to a slower TQ when the relative phase is   −90°. The toroidal radiation asymmetry is worse with the locked mode. The results suggest that the 3D effect between the injected impurities and the 2/1 locked mode is important during the disruption mitigation process. (paper)

[en] The injection of a large amount of impurities is one of the possible ways of mitigating disruption in large-scale tokamaks. The deposition of impurities at the center of the plasma is the key to the radiation of plasma energy and suppression of runaway. The interaction of the gas jet with the rational surfaces has been studied by scanning the plasma current. The experimental results show that the injection of a massive amount of argon can cool the plasma from the edge to the core region, and the cooling process is accompanied by different magnetohydrodynamic (MHD) modes when the gas jet reaches the corresponding rational surfaces. It is observed that with different edge safety factors and electron density, gas injection can induce different poloidal modes at first. Then, the poloidal mode traverses to lower m (where m is the poloidal mode number) MHD activities until a 2/1 mode is initiated and a thermal quench is started. The experimental results show that the penetration of a gas jet across the rational surfaces is faster in the plasmas with pre-existing large 2/1 tearing modes, which indicates that the 2/1 mode plays an important role in the penetration process. Disruptions triggered by supersonic molecular beam injection display a slower cooling process compared with massive gas injection, which can be divided into four stages. The dominant poloidal mode transition from m  =  3 to m  =  2 is associated with electron temperature recovery. (paper)

[en] The generation of runaway electrons during disruptions poses a serious threat for the operation of ITER. The efficiency of the injection of large amounts of impurities by massive gas injection or shattered pellet injection to achieve runaway suppression might be compromised due to low gas mixture efficiency and the high Rosenbluth density for runaway suppression. The transport of runaway electrons is dominated by magnetic perturbations. The magnetic perturbations have the advantage of expelling the runaway seeds before they reach high energy. Robust runaway suppression has been reached on J-TEXT with mode locking by the application of m/n  =  2/1 resonant magnetic perturbations before the thermal quench. The mode locking implemented large magnetic islands inside the plasma which acted as an explosive bomb during disruptions and led to stronger stochasticity in the whole plasma cross section. The NIMROD simulation indicates that this strong stochasticity expels the runaway seeds and results in runaway free disruptions on J-TEXT. This might provide an alternative runaway suppression technique during disruptions for large-scale tokamaks. (paper)

[en] Highlights: • Some lines from X-ray imaging crystal spectrometer (XICS) can be enhanced by non-thermal electrons, such as q, r satellite lines and z lines. • Analyze the non-thermal phenomena can reduce the error of electron temperature deduced from the intensity ratio of different lines of the He-like argon spectra from XICS. • XICS can be a tool to measure the non-thermal phenomena from these enhanced lines. - Abstract: A high spectra resolution X-ray imaging crystal spectrometer has been implemented on J-TEXT Tokamak for the measurements of K_α spectra of helium-like argon and its satellite lines. The wavelength range of K_α spectra of helium-like argon is from 3.9494 Å to 3.9944 Å that includes the resonance line w, intercombination lines x and y, forbidden line z and numerous satellite lines, referenced using standard Gabriel notation. In low-density discharge, the intensity of q, r satellite lines and z lines can be significantly enhanced by non-thermal electrons. Non-thermal electrons are produced due to the low plasma density. The high hard X-ray flux from NaI detector and significant downshift electron cyclotron emissions from energetic runaway electrons also indicated that there is a large population of runaway electrons in the low-density discharge. The non-thermal part of electrons can affect the excitation/transition equilibrium or ionization/recombination equilibrium. The q line is mainly produced by inner-shell excitation of lithium-like argon, and the r line is partially produced by inner-shell excitation of lithium-like argon and dielectronic recombination of helium-like argon.

[en] An RPC carpet covering ∼ 10⁴ m² (ARGO-YBJ experiment) will be installed in the YangBaJing Laboratory (Tibet, P.R. China) at an altitude of 4300 m a.s.l.. A test-module of ∼ 50 m² has been put in operation in this laboratory and about 10⁶ air shower events have been collected. The carpet capability of reconstructing the shower features is presented

[en] Bakelite RPCs, assembled according to the ARGO design, have been operated in the high altitude Laboratory of YBJ using dedicated electronics to pick-up the streamer signal. Here we report on the results concerning absorbed current, single counting rate, efficiency and time resolution. Environmental data concerning the operating temperature inside the ARGO experimental hall are also reported

[en] A 50 m² RPC carpet was operated at the YanBaJin Cosmic Ray Laboratory (Tibet) located 4300 m a.s.l. The performance of RPCs in detecting Extensive Air Showers was studied. Efficiency and time-resolution measurements at the pressure and temperature conditions typical of high mountain laboratories, are reported

[en] We present the ARGO-YBJ experiment, a full coverage detector placed at high altitude (∼ 4300 m a.s.l.) that exploits the RPC technique. Results of a test experiment performed at Yanbajing site, with a full coverage RPC carpet of 50 m² are also presented