An E-band multi-channel Doppler backscattering system on EAST.

An E-band (60-90 GHz) multi-channel Doppler backscattering (DBS) system with X-mode polarization has been installed on the Experimental Advanced Superconducting Tokamak (EAST), which can measure the turbulence at five different radial locations simultaneously. This system can launch 31 fixed microwave frequencies in the range of 60-90 GHz with a 1 GHz interval into the plasma, and five probing signals are selected by employing a reference signal and multiple filters. During experiments, the frequency of the reference signal is tunable in the E-band, and the selected probing signals can be changed as needed without any other adjustments, which can be performed in one shot or between shots. Furthermore, the incident angle can be adjusted from -10° to 20°, and the wavenumber range is 4-25 cm-1 with a wavenumber resolution of Δk/k ≤ 0.35. Ray tracing simulations are employed to calculate the scattering locations and the perpendicular wavenumber. In this article, the hardware design, ray tracing, and initial results obtained from the EAST plasma will be presented.

[Review on biological effects and mechanism of Ac-SDKP].

N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is an endogenous short peptide produced through the continuous hydrolysis of Thymosin ß4 by meprin-α and prolyl oligopeptidase. It has the functions of immune regulation, promoting angiogenesis, tumorigenesis and anti-fibrosis in organs. In this paper, according to some our research results and related literatures in recent years, a review of Ac-SDKP research progress was written.

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

High-ß_{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-ß_{θe} regime.

The cross-polarization scattering system for the magnetic fluctuation measurement in the Experimental Advanced Superconducting Tokamak.

The cross-polarization scattering (CPS) system for magnetic fluctuation measurements in the Experimental Advanced Superconducting Tokamak (EAST) has been designed and installed. Different from the Doppler reflectometer (DR) system, the CPS system detects the perpendicular polarization of the electromagnetic wave induced by magnetic fluctuations B̃. The CPS system in the EAST has been developed from the existing Doppler reflectometer system, and they are integrated together for simultaneous measurement of magnetic and density fluctuations. Ray-tracing simulations are used to calculate the scattering locations and the wavenumber coverage of the magnetic fluctuation for CPS. In the experiments, the CPS and DR system data were different in Doppler shift, amplitude, and spectrum broadening. In this article, the hardware design, the ray tracing, and the preliminary results of the system in the EAST are presented.

SNHG1 promotes proliferation, invasion and EMT of prostate cancer cells through miR-195-5p.

OBJECTIVE: To explore the correlation of SNHG1 with miR-195-5p, and the mechanism of SNHG1 in prostate cancer (PC). PATIENTS AND METHODS: The prostate cancer patients admitted to our hospital were selected, and the cancer tissues (n=142) and adjacent tissues (n=142) of the patients were collected during the operation. The content of SNHG1 and miR-195-5p in PC was observed, and the PC cell lines were transfected to detect the proliferation, invasion, apoptosis and Epithelial-Mesenchymal Transitions (EMT) capability. RESULTS: SNHG1 was enhanced in PC, while miR-195-5p was decreased (p<0.05). After transfection of DU-145 and PC-3, it was found that silence of SNHG1 or overexpression of miR-195-5p could evidently inhibit the proliferation and invasion, increase the apoptosis (p<0.05). After detecting the EMT markers, it was found that after silencing SNHG1 or over-expressing miR-195-5p, E-cadherin enhanced while N-cadherin and Vimentin reduced (p<0.05). Double Luciferase reports confirmed that SNHG1 could act as a sponge to regulate miR-195-5p, and correlation analysis showed that SNHG1 had a negative correlation with miR-195-5p. Rescue experiments found that si-SNHG1 co-transfected with miR-195-5p-inhibitor could reverse the inhibitory role of si-SNHG1 on prostate cancer cells. CONCLUSIONS: SNHG1 can mediate the proliferation, invasion and EMT of PC by regulating miR-195-5p expression.

Five-channel tunable W-band Doppler backscattering system in the experimental advanced superconducting tokamak.

A 5-channel Doppler backscattering system has been designed and installed in the Experimental Advanced Superconducting Tokamak (EAST). Through an I/Q-type double sideband modulator and a frequency multiplier, an array of finely spaced (Δf = 400 MHz) frequencies that span 1.6 GHz has been created. The center of the array bandwidth is tunable within the range of 75-97.8 GHz, which covers most of the W band (75-110 GHz). The incident angle can be adjusted from -4° to 12°, and the wavenumber range is 4-15 cm-1 with a wavenumber resolution of Δk/k ≤ 0.35. Ray tracing is used to calculate the scattering location and the scattering wavenumber. This article details the hardware design, the ray tracing, and the preliminary experimental results from EAST plasmas.

A novel, tunable, multimodal microwave system for microwave reflectometry system.

Based on a new technique, a tunable, multi-channel system that covers the Q-band (33-55 GHz) is presented in this article. It has a potential use of the Doppler backscattering system diagnostic that can measure the turbulence radial correlation and the perpendicular velocity of turbulence by changing the incident angle. The system consists primarily of a double-sideband (DSB) modulation and a multiplier, which creates four probing frequencies. The probing frequency enables the simultaneous analysis of the density fluctuations and flows at four distinct radial regions in tokamak plasma. The amplitude of the probing frequency can be adjusted by the initial phase of the intermediate frequency (IF) input from the double-sideband, and the typical flatness is less than 10 dB. The system was tested in the lab with a rotating grating, and the results show that the system can operate in the frequency range of 33-55 GHz with a Q-band multitude and that the power of each channel can be adjusted by the phase of the IF input of DSB.

[Comparison of the diagnostic efficiency in breast malignancy between cone beam breast CT and mammography in dense breast].

Objective: To compare the diagnostic efficiency of lesion in dense breast between cone beam breast computer tomography (CBBCT) and mammography. Methods: From May 2012 to August 2014, 160 patients with 165 breasts who underwent mammography and CBBCT examinations were included in this study. The diagnostic results of CBBCT and mammography were reviewed and compared with pathological results. Results: In the 165 breast, 24 were dense breasts and 141 were dense breasts. The diagnostic results were similar in 109 lesions, but different in 56 lesions. According to the analysis of the 165 breasts using receiver operation characteristics (ROC) curve, the area under the ROC curves (AUC) of CBBCT and mammography were 0.923 (95%CI: 0.878-0.967, P<0.05) and 0.959 (95%CI: 0.926-0.992, P<0.05), respectively. With Breast Imaging-Reporting and Data System (BI-RADS) 4b as the critical value, the sensitivity and specificity were 70.0% and 98.7% using mammography, and 83.3% and 97.3% using CBBCT, respectively. The AUC of CBBCT and mammography of the 141 dense breasts was 0.919(95%CI: 0.868-0.969, P<0.05) and 0.973(95%CI: 0.947-0.999, P<0.05), respectively. With BI-RADS 4b as the critical value, the sensitivity and specificity were 69.0% and 98.6% by mammography, and 83.1% and 98.6% by CBBCT, respectively. Conclusions: CBBCT showed higher sensitivity and specificity in the diagnosis of breast malignant tumors compared to mammography. It is expected to be applied to breast cancer detection in the future, especially in dense breast.

[Effects of metformin on papillary thyroid carcinoma in nude rats model].

Objective:To establish an subcutaneous xenotransplanted tumor model of papillary thyroid carcinoma (PTC) and investigate the role of metformin in apoptosis of PTC.Method:Model rats were randomly divided into four groups: control group, Met group and Met+DM group. The tumor volumes were recorded each week. Flow cytometry was used to detect the apoptosis rate of tumor. Immunohistochemistry was used to detect CyclinD1 and the cellular proliferative activity index PCNA and Ki-67.Result:Compared to the control group,there were a significant decrease in tumor volume and antitumor effect in Met and Met+DM groups. The apoptosis rate increased in Met and Met+DM groups. While compared with the control group, the expressions of PCNA,CyclinD1 and Ki-67 significantly decreased in Met and Met+DM groups. There was no difference between Met and Met+DM group.Conclusion:The effect of Metformin on inhibiting tumor growth were related with the imbalance of cell proliferation and apoptosis.

An eight-channel Doppler backscattering system in the experimental advanced superconducting tokamak.

Doppler backscattering system can measure the perpendicular velocity and fluctuation amplitude of the density turbulence with intermediate wavenumber. An eight-channel Doppler backscattering system has been installed in the Experimental Advanced Superconducting Tokamak (EAST), which can probe eight different radial locations simultaneously by launching eight fixed frequencies (55, 57.5, 60, 62.5, 67.5, 70, 72.5, 75 GHz) into plasma. The quasi-optical system consists of circular corrugated waveguide transmission, a fixed parabolic mirror, and a rotatable parabolic mirror which are integrated with quasi-optics front-end of the profile reflectometer inside the vacuum vessel. The incidence angle can be chosen from 5° to 12°, and the wavenumber range is 2-15/cm with the wavenumber resolution Δk/k≤0.21. Ray tracing simulations are used to calculate the scattering locations and the perpendicular wavenumber. The dynamic range of this new eight-channel Doppler backscattering system can be as large as 40 dB in the EAST. In this article, the hardware design, the ray tracing, and the preliminary experimental results in the EAST will be presented.

A novel approach to estimating the Doppler shift frequency from quadrature mixer output.

Doppler backscattering systems (DBSs) have been widely used in magnetic confinement fusion devices to measure the density fluctuations and propagation velocity of turbulence. However, the received signals of a DBS usually include both zero-order reflection and backscattering components, which results in interference in calculating the Doppler shift frequency from the backscattering components. A novel method is introduced here for estimating the Doppler shift frequency by separating the zero-order reflection and backscattering components using the cross-phase spectrum between the I-signal and Q-signal from a quadrature mixer, based on the difference in symmetrical characteristics between the zero-order reflection and backscattering signal spectra. It is proven that this method is more effective than traditional approaches, such as multiple signal classification and fast Fourier transformation, for extracting Doppler shift information.

[Metformin induced apoptosis of papillary thyroid carcinoma BCPAP cells].

Objective:To investigate the role of metformin in inducing apoptosis of papillary thyroid carcinoma BCPAP cells. Method:Using MTT methods to detect effects of metformin on cell proliferation of BCPAP in different concentrations (0 mmol/L, 1 mmol/L, 5 mmol/L, 10 mmol/L, 20 mmol/L) and time course (0 h, 4 h, 8 h, 16 h, 24 h, 48 h). The experiment was divided into four groups: Con, Met, Met+Sal and Met+DM, flow cytometry to detect the rate of apoptosis of BCPAP. Then detect the protein expressions of CHOP, GRP78 and Caspase-12 of 4 groups by Western blot. Result:Compared with the experimental control group, the percentage of cell proliferation index significantly decreased in metformin (0-20 mmol/L and 0-48 h) treatment group. Compared with the experimental control group, the percentage of apoptosis cells significantly increased in metformin treatment group. Compared with the control group, the protein expressions of GRP78, CHOP and Caspase-12 were significantly increased in Met group; While compared with the Met group, the protein expressions of GRP78, CHOP and Caspase-12 were significantly inhibited in the Met+Sal group. Conclusion:Metformin can induced availably BCPAP cell apoptosis by activating endoplasmic reticulum stress mechanism.

Influence of lithium coating on the optics of Doppler backscatter system.

This paper presents the first investigation of the effect of lithium coating on the optics of Doppler backscattering. A liquid lithium limiter has been applied in the Experimental Advanced Superconducting Tokamak (EAST), and a Doppler backscattering has been installed in the EAST. A parabolic mirror and a flat mirror located in the vacuum vessel are polluted by lithium. An identical optical system of the Doppler backscattering is set up in laboratory. The power distributions of the emission beam after the two mirrors with and without lithium coating (cleaned before and after), are measured at three different distances under four incident frequencies. The results demonstrate that the influence of the lithium coating on the power distributions are very slight, and the Doppler backscattering can work normally under the dosage of lithium during the 2014 EAST campaign.

Sulfur dioxide inhibits vascular smooth muscle cell proliferation via suppressing the Erk/MAP kinase pathway mediated by cAMP/PKA signaling.

The present study was designed to investigate the role of endogenous sulfur dioxide (SO2) in vascular smooth muscle cell (VSMC) proliferation, and explore the possible role of cross-talk between cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) and extracellular signal-regulated kinase (Erk)/mitogen-activated protein kinase (MAPK) pathways in this action. By cell counting, growth curve depict, flow cytometry and bromodeoxyuridine (BrdU) labeling assays, we found that SO2 inhibited VSMC proliferation by preventing cell cycle progression from G1 to S phase and by reducing DNA synthesis. SO2 synthase aspartate aminotransferase (AAT1 and AAT2) overexpression significantly inhibited serum-induced proliferating cell nuclear antigen (PCNA) protein expression in VSMCs, demonstrated by western blot analysis. Moreover, overexpression of AAT1 or AAT2 markedly reduced incorporation of BrdU in serum-treated VSMCs. By contrast, either AAT1 or AAT2 knockdown significantly exacerbated serum-stimulated VSMC proliferation. Thus, both exogenous- and endogenous-derived SO2 suppressed serum-induced VSMC proliferation. However, annexin V-propidium iodide (PI) staining and cell cycle analysis demonstrated that SO2 did not influence VSMC apoptosis in the serum-induced proliferation model. In a platelet-derived growth factor (PDGF)-BB-stimulated VSMC proliferation model, SO2 dephosphorylated the active sites of Erk1/2, MAPK kinase 1/2 and RAF proto-oncogene serine/threonine-protein kinase (c-Raf) induced by PDGF-BB. However, the inactivation of the three kinases of the Erk/MAPK pathway was not due to the separate interferences on them by SO2 simultaneously, but a consequence of the influence on the upstream activity of the c-Raf molecule. Hence, we examined the cAMP/PKA pathway, which could inhibit Erk/MAPK transduction in VSMCs. The results showed that SO2 could stimulate the cAMP/PKA pathway to block c-Raf activation, whereas the Ser259 site on c-Raf had an important role in SO2-induced suppression of Erk/MAPK pathway. The present study firstly demonstrated that SO2 exerted a negative regulation of VSMC proliferation via suppressing the Erk/MAPK pathway mediated by cAMP/PKA signaling.

Microwave Doppler reflectometer system in the Experimental Advanced Superconducting Tokamak.

A Doppler reflectometer system has recently been installed in the Experimental Advanced Superconducting (EAST) Tokamak. It includes two separated systems, one for Q-band (33-50 GHz) and the other for V-band (50-75 GHz). The optical system consists of a flat mirror and a parabolic mirror which are optimized to improve the spectral resolution. A synthesizer is used as the source and a 20 MHz single band frequency modulator is used to get a differential frequency for heterodyne detection. Ray tracing simulations are used to calculate the scattering location and the perpendicular wave number. In EAST last experimental campaign, the Doppler shifted signals have been obtained and the radial profiles of the perpendicular propagation velocity during L-mode and H-mode are calculated.

Dynamics of low-intermediate-high-confinement transitions in toroidal plasmas.

The dynamic features of the low-intermediate-high-(L-I-H) confinement transitions on HL-2A tokamak are presented. Here we report the discovery of two types of limit cycles (dubbed type-Y and type-J), which show opposite temporal ordering between the radial electric field and turbulence intensity. In type-Y, which appears first after an L-I transition, the turbulence grows first, followed by the localized electric field. In contrast, the electric field leads type-J. The turbulence-induced zonal flow and pressure-gradient-induced drift play essential roles in the two types of limit cycles, respectively. The condition of transition between types-Y and -J is studied in terms of the normalized radial electric field. An I-H transition is demonstrated to occur only from type-J.

First evidence of the role of zonal flows for the L-H transition at marginal input power in the EAST tokamak.

A quasiperiodic Er oscillation at a frequency of <4 kHz, much lower than the geodesic-acoustic-mode frequency, with a modulation in edge turbulence preceding and following the low-to-high (L-H) confinement mode transition, has been observed for the first time in the EAST tokamak, using two toroidally separated reciprocating probes. Just prior to the L-H transition, the Er oscillation often evolves into intermittent negative Er spikes. The low-frequency Er oscillation, as well as the Er spikes, is strongly correlated with the turbulence-driven Reynolds stress, thus providing first evidence of the role of the zonal flows in the L-H transition at marginal input power. These new findings not only shed light on the underlying physics mechanism for the L-H transition, but also have significant implications for ITER operations close to the L-H transition threshold power.

Characterizations of low-frequency zonal flow in the edge plasma of the HL-2A tokamak.

A low-frequency (<4 kHz), poloidally and toroidally symmetrical potential structure that peaks near zero frequency is observed in the edge plasma of the HL-2A tokamak. The axisymmetry structure exhibits a radial coherence length less than 1 cm. These characteristics are consistent with the theoretically predicted low-frequency zonal flows (LFZF). The radial wave-number frequency spectra of the LFZF show that the LFZF packets propagate both outwards and inwards. The geodesic acoustic mode (GAM) is found to coexist with the LFZF, and the LFZF is found to modulate the GAM and ambient turbulence with in-phase and antiphase relations, respectively, through an envelope analysis.

Toroidal symmetry of the geodesic acoustic mode zonal flow in a tokamak plasma.

The toroidal symmetry of the geodesic acoustic mode (GAM) zonal flows is identified with toroidally distributed three step Langmuir probes at the edge of the HuanLiuqi-2A (commonly referred to as HL-2A) tokamak plasmas for the first time. High coherence of both the GAM and the ambient turbulence for the toroidally displaced measurements along a magnetic field line is observed, in contrast with the high coherence of the GAM but low coherence of the ambient turbulence when the toroidally displaced measurements are not along the same field line. The radial and poloidal features of the flows are also simultaneously determined. The nonlinear three wave coupling between the high frequency turbulent fluctuations and the flows is demonstrated to be a plausible formation mechanism of the flows.

Construction of stabilized proteins by combinatorial consensus mutagenesis.

We constructed stabilized variants of beta-lactamase (BLA) from Enterobacter cloacae by combinatorial recruitment of consensus mutations. By aligning the sequences of 38 BLA homologs, we identified 29 positions where the E.cloacae gene differs from the consensus sequence of lactamases and constructed combinatorial libraries using mixtures of mutagenic oligonucleotides encompassing all 29 positions. Screening of 90 random isolates from these libraries identified 15 variants with significantly increased thermostability. The stability of these isolates suggest that all tested mutations make additive contributions to protein stability. A statistical analysis of sequence and stability data identified 11 mutations that made stabilizing contributions and eight mutations that destabilized the protein. A second-generation library recombining these 11 stabilizing mutations led to the identification of BLA variants that showed further stabilization. The most stable variant had a mid-point of thermal denaturation (Tm) that was 9.1 degrees C higher than the starting molecule and contained eight consensus mutations. Incubation of three stabilized BLA variants with several proteases showed that all tested isolates have significantly increased resistance to proteolysis. Our data demonstrate that combinatorial consensus mutagenesis (CCM) allows the rapid generation of protein variants with improved thermal and proteolytic stability.