Experimental Evidence of Intrinsic Current Generation by Turbulence in Stationary Tokamak Plasmas

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.

Diagnostic development for parallel wave-number measurement of lower hybrid waves in EAST

An eight-channel magnetic probe diagnostic system has been designed and installed adjacent to the 4.6 GHz lower hybrid (LH) grill antenna in the low-field side of the Experimental Advanced Superconducting Tokamak (EAST) in order to study the n_∥ evolution of LH waves in the first pass from the launcher to the core plasma. The magnetic probes are separated by 6.6 mm, which allows measurement of the dominant parallel refractive index n_∥ up to n_∥ = 5 for 4.6 GHz LH waves. The magnetic probes are designed to be sensitive to the magnetic field component perpendicular to the background magnetic field with a slit on the casing that encloses the probe. The intermediate frequency stage, which consists of two mixing stages, down-coverts the frequency of the measured wave signals at 4.6 GHz to 20 MHz. A bench test demonstrates the phase stability of the magnetic probe diagnostic system. By evaluating the phase variation of the measured signals along the background magnetic field, the dominant n_∥ of the LH wave in the scrape-off layer has been deduced during the 2019 experimental campaign. In the low density plasma, the measured dominant n_∥ of the LH waves is about 2.1, corresponding to the main peak 2.04 of the launched n_∥ spectrum. n_∥ deduced by the least-squares linear fit method remains near this value in the low density plasma with a high spatial correlation magnitude of 0.9. With an eight-channel probe system, a wave-number spectrum has also been deduced, which has a peak near to the measured dominant n_∥.

Magnetic topology changes induced by lower hybrid waves and their profound effect on edge-localized modes in the EAST tokamak

Strong mitigation of edge-localized modes has been observed on Experimental Advanced Superconducting Tokamak, when lower hybrid waves (LHWs) are applied to H-mode plasmas with ion cyclotron resonant heating. This has been demonstrated to be due to the formation of helical current filaments flowing along field lines in the scrape-off layer induced by LHW. This leads to the splitting of the outer divertor strike points during LHWs similar to previous observations with resonant magnetic perturbations. The change in the magnetic topology has been qualitatively modeled by considering helical current filaments in a field-line-tracing code.

Shape separation of nanometer gold particles by size-exclusion chromatography

The shape separations of suspended gold nanoparticles were investigated using size-exclusion chromatography. The separations in shapes were identified by examining the 3-D chromatograms obtained by employing a diode-array detection system and were further confirmed by analyzing TEM images of fractional collection of particles. This shape separation was achieved by adding a mixed-surfactant system containing sodium dodecyl sulfate and poluoxyethylene (23) dodecanol (Brij-35) into the eluent, which apparently affects the adsorption behaviors of both rodlike and spherical Au nanoparticles onto the column packing materials. While the overall particle gross sizes of these two shapes were similar, the baseline resolution was unfortunately not obtainable. However, the absorption spectra from the diode-array detector could be utilized to interpret the shapes of Au nanoparticles. The potential capability for the size separation of Au nanoparticles by size-exclusion chromatography with diode-array detection was also demonstrated.

Combined evaluation of centromere protein H and Ki-67 as prognostic biomarker for patients with gastric carcinoma

AIM

Centromere protein H (CENP-H) is one of the essential components of the human active kinetochore which close links with carcinogenesis. Its expression and clinical value of prognostic prediction for gastric cancer (GC) is unclear.

METHODS

CENP-H and Ki-67 expressions in specimens from 166 patients with GC were determined by tissue microarrays and immunostaining. Their correlations between patients' clinicopathologic features and prognosis were explored. For mechanisms, quantitative CENP-H examination on gastric cancer tissue and cell lines was performed via real-time quantitative PCR and Western Blot. Its effect on Survivin expression and cell function was evaluated via CENP-H knocking down (SiRNA) or overexpression.

RESULTS

Highly expression of CENP-H was found in 85 of 166 GC, showing a significant correlation with tumour size, depth of infiltration, lymph node metastasis, distant metastasis and UICC staging of gastric carcinoma (P < 0.05), as well as clinical prognosis (coefficient = 0.550, P < 0.001). Multivariate analysis revealed that combined CENP-H and Ki67 expression was a more valuable independent prognostic predictor for patients' survival (hazard ratio, 2.18; P = 0.0109). Furthermore, total mRNA and protein expression of CENP-H in GC tissue and cell lines were noticeably increased. Survivin expression and cell function including growth, proliferation and clonogenic ability could be inhibited by CENP-H siRNA or enhanced by overexpressing CENP-H.

CONCLUSION

High expression of CENP-H in GC indicates poor prognosis and Survivin may mediate its procancer role. Combined evaluation of CENP-H and Ki-67 aids in predicting the clinical prognosis.

Verapamil modulates LPS-induced cytokine production via inhibition of NF-kappa B activation in the liver

OBJECTIVE

To investigate the effect of verapamil on Lipopolysaccharide (LPS)-induced cytokines [tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-10 (IL-10)] and nuclear factor kappa B (NF-kappa B) in the liver.

METHODS AND MATERIALS

Adult male Sprague-Dawley rats were randomly divided into seven groups of eight rats each: control rats treated with saline (0.9 % NaCl); rats treated with saline and then challenged intraperitoneally with LPS (10 mg/kg); rats treated intraperitoneally with different levels of verapamil (1, 2.5, 5, 10 mg/kg) and then challenged with LPS (10 mg/kg); and rats treated only with verapamil (10 mg/kg). TNF-alpha, IL-6, IL-10 and NF-kappa B in the liver tissues were investigated as well as the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) one hour after LPS injection.

RESULTS

LPS alone stimulated production of TNF-alpha, IL-6 and IL-10, and activated NF-kappa B in the liver. Pretreatment with verapamil before LPS challenge reduced acute liver injury, down-regulated production of LPS-induced pro-inflammatory cytokines (TNF-alpha and IL-6), up-regulated production of anti-inflammatory cytokines (IL-10) and inhibited NF-kappa B activation in the liver in a dose-dependent manner.

CONCLUSION

Verapamil can attenuate acute liver injury by down-regulating the production of TNF-alpha and IL-6 and up-regulating IL-10 in the liver, possibly via inhibition of NF-kappa B.

[The effect of intravenous alimentation on protein synthesis after major operation]

The whole body protein was found to decline by 16.4% in patients after radical gastrectomy without IVN support, and the levels of visceral proteins, such as serum albumin, C-reactant and fibronectin, also obviously decreased. If IVN support was given after operation, the whole body protein synthesis was 57.7% higher than that in the controlled group. The blood levels of visceral proteins were also elevated, with a significant difference in the fibronectin concentration in IVN group as compared with either preoperative or controlled value.

Intraoperative coronary venography in observing changes of portal blood flow after portal-azygos disconnection

Intraoperative coronary venography was performed in 24 patients before and after portal-azygos disconnection for portal hypertension. Before the procedure the portal vein was found to be communicated with cardial and esophageal veins by two pathways, i,e., from the esophageal and gastric branches of the coronary vein to the esophageal varices, with the latter branches by way of the gastric intramural venula. The portal blood flow was postulated to be hepatofugal because the portal trunk could not be seen venographically. Coronary venography done after the disconnection revealed no pericardial and esophageal varices and the portal vein with hepatopetal blood flow. We conclude that the operation had the advantage of complete disconnection between the portal vein and the cardio-esophageal varices, thus preventing the bleeding from the varix and increasing hepatopetal blood flow.

[Effect of intravenous nutrition on protein catabolism in stomach cancer patients after radical gastrectomy]

12 patients with advanced gastric cancer after radical gastrectomy were randomized into two groups to investigate the mechanism of protein loss and to evaluate the effect of intravenous nutrition (IVN) support on protein catabolism postoperatively. The mean weight loss was 600 g/d, and the amount of total nitrogen loss was 70 g (9.6 +/- 1.73 g/d) within a week after surgery. The whole body protein breakdown rate increased by 45.2% on the 5th day. The net protein loss was higher in the control group than that in the IVN group. The parameters represented protein catabolism, such as total nitrogen, creatinine and 3-MH excretion in urine and CPK in serum showed a higher value after surgery. However, there was no significant difference between the two groups. The results show that the loss of nitrogen in the patients after major surgery is mainly due to the increase of protein breakdown and IVN support after surgery could not reduce the protein catabolism, but it could elevate rate of protein synthesis.

[Effect of hypocaloric nutritional support on protein metabolism in patients with gastric cancer after radical gastrectomy]

In this study, 17 patients with advanced gastric cancer were randomized into 3 groups to investigate the changes of protein metabolism-and the nitrogen sparing effect of both hypo-and hypercaloric nutrition after radical gastrectomy. Group 1, as control (n = 6) receiving 14 +/- 1.2 kcal/kg/d with no protein; Group 2, as hypercaloric (n = 6) receiving 32 +/- 3.8 kcal/kg/d(by Harris Benedict Equation) and 1.23 g/kg/d of protein; Group 3, hypocaloric (n = 5) with less than 50% of calories and the same amount of protein as in Group 2. 15N-glycine was used to evaluate the protein synthesis and breakdown rates, and the nitrogen balance, nitrogen retention, plasma proteins (albumin, fibronectin), protein catabolic parameters such as nitrogen, creatinine, 3-MH excretion in the urine, and CPK in serum were evaluated. It was found that although in all three groups there was significant protein catabolism after surgery, there was significant reduction of negative nitrogen balance in Group 2 (-2.7 +/- 2.1 g/d) and Group 3 (-2.8 +/- 3.1 g/d) as compared with Group 1 (-9.6 +/- 1.73 g/d). Nitrogen retention rate was 75 +/- 4.5% in Group 3 and 78.6 +/- 3.9% in Group 2. Postoperative fibronectin concentration in Group 1 was also statistically different from Group 2 or Group 3. Protein synthesis was increased by 57.7% and 60.6%, and breakdown by 14.9% and 18.9% respectively in Group 2 and 3. It was concluded that hypocaloric nutrition was as effective as hypercaloric support in this situation.