A high-density and high-confinement tokamak plasma regime for fusion energy

The tokamak approach, utilizing a toroidal magnetic field configuration to confine a hot plasma, is one of the most promising designs for developing reactors that can exploit nuclear fusion to generate electrical energy1,2. To reach the goal of an economical reactor, most tokamak reactor designs3-10 simultaneously require reaching a plasma line-averaged density above an empirical limit-the so-called Greenwald density11-and attaining an energy confinement quality better than the standard high-confinement mode12,13. However, such an operating regime has never been verified in experiments. In addition, a long-standing challenge in the high-confinement mode has been the compatibility between a high-performance core and avoiding large, transient edge perturbations that can cause very high heat loads on the plasma-facing-components in tokamaks. Here we report the demonstration of stable tokamak plasmas with a line-averaged density approximately 20% above the Greenwald density and an energy confinement quality of approximately 50% better than the standard high-confinement mode, which was realized by taking advantage of the enhanced suppression of turbulent transport granted by high density-gradients in the high-poloidal-beta scenario14,15. Furthermore, our experimental results show an integration of very low edge transient perturbations with the high normalized density and confinement core. The operating regime we report supports some critical requirements in many fusion reactor designs all over the world and opens a potential avenue to an operating point for producing economically attractive fusion energy.

Experimental Validation of a Kinetic Ballooning Mode in High-Performance High-Bootstrap Current Fraction Fusion Plasmas

We report the observation of a set of coherent high frequency electromagnetic fluctuations that leads to a turbulence induced self-regulating phenomenon in the DIII-D high bootstrap current fraction plasma. The fluctuations have frequency of 130-220  kHz, the poloidal wavelength and phase velocity are 16-30  m^{-1} and ∼30  km/s, respectively, in the outboard midplane with the estimated toroidal mode number n∼5-9. The fluctuations are located in the internal transport barrier (ITB) region at large radius and are experimentally validated to be kinetic ballooning modes (KBM). Quasilinear estimation predicts the KBM to be able to drive experimental particle flux and non-negligible thermal flux, suggesting its significant role in regulating the ITB saturation.

Identification of two-phase flow patterns based on capacitance data of electrical capacitance tomography with semi-supervised generative adversarial network

Currently, the flow pattern identification algorithms based on ECT (electrical capacitance tomography) technology have low identification accuracy for complex flow patterns and require a large amount of label data for learning. A novel flow pattern identification method based on a semi-supervised generative adversarial network (SGAN) with capacitance data of ECT is proposed. First, the principles of the ECT technique and general GAN are briefly described, and the model parameters, loss function, and training process of the SGAN are explained in detail. Second, a capacitance data sample set of 11 400 random flow patterns is constructed by co-simulations of COMSOL and MATLAB, and then, the SGAN and BP (back propagation) and SVM (support vector machine) network models are trained and validated by the training set. Finally, static experiments are conducted on the self-developed ECT system, and the identification results of different algorithms are compared and analyzed by modifying the label sample size of the training set. The experimental results show that SGAN maintains a higher average identification accuracy under the training condition where the number of label samples of SGAN is ten times smaller than that of the other two algorithms.

The carbon footprint response to projected base stations of China's 5G mobile network

While the rapid expansion of China's 5G mobile network helps to speed up the nation's economic and social development, it tends to release more CO₂ due to the 5G's significant energy demand, hampering sustainable development of the 5G network. Previous assessments of CO₂ emissions from China's 5G development were based on a projected 5G network ranging from six to fifteen million base stations with the absent of a convincing business model in 5G's application. Under the scenario of business-estimated six million base stations in 2030, the share of electricity consumed by China's 5G networks in 2030 could reach 8.4 % of the national total power generation, causing 0.44 GtCO₂/yr CO₂ emissions. We collected 5G base station numbers in 2020 and 2021 in 31 provinces and province-level municipalities (PLM), the period with the rapid growth of the 5G base stations in China. We linked these provincial base stations with provincial Gross Domestic Product (GDP), population (POP), and big data development level (BDDL) and established a statistical model to predict 5G base stations by 2030. The model predicted 2-5 million 5G base stations by 2030, considerably lower than the business-projected base station number. Under the model predicted 5G base stations, China's 5G network could yield 0.15-0.29 GtCO₂/yr emissions subject to the nation's BDDL from 40 to 80 % by 2030. Both 5G base stations and CO₂ emissions are significantly lower than the previous estimates. We decomposed the CO₂ footprint of China's 5G networks and assessed the contribution of the number of 5G base stations and mobile data traffic to 5G-induced CO₂ emissions. We find that increasing the application of clean energy and promoting energy efficiency can reduce CO₂ emissions in the 5G network. To more accurately estimate 5G's climate effect, we propose that it urgently needs to improve vivid 5G business models.

Drivers of Global Methane Emissions Embodied in International Beef Trade

Increasing worldwide demand for beef products promotes international beef trade. Cattle raising and beef products as significant sources of methane (CH₄) emissions have received widespread concerns. However, the factors driving CH₄ emissions embodied in the global beef trade have not been quantified. Here, we evaluate international beef trade-induced CH₄ emissions and assess the contribution of the five driving factors to changes in CH₄ emissions embodied in the beef trade from 2000 to 2018. We show that driven by increasing population and meat demands, the global beef trade-induced CH₄ emissions increased continuously in the past two decades, with total emissions of 9337.3 Gg in 2018. The drivers that could potentially reduce trade-related emissions are emission intensities in beef exporting countries and beef importing countries' selections of their beef suppliers. Together, these two driving factors reduced CH₄ emissions by 923.5 Gg from 2012 to 2018. Results suggest that efforts should be made to reduce the emission intensity via improving cattle feed and feeding practices in beef exporting countries. Beef importing countries could also contribute to CH₄ emission reduction by selecting those beef exporting countries with low emission intensities.

Tropospheric Ozone Perturbations Induced by Urban Land Expansion in China from 1980 to 2017

Urbanization perturbs air pollutants from a dynamic and thermodynamic perspective, which has inspired extensive investigations in China due to rapid urban land expansion in the past four decades. However, knowledge gaps remain in the long-term and nationwide responses to air pollutants to urbanization. The evolution of tropospheric ozone associated with urban land expansion across China was assessed from 1980 to 2017 using a coupled WRF-Chem model based on a recently updated land use change (LUC) data set. The results revealed that urban-land expansion drove growing ozone trends for this period and contributed about 3-9% to its summer maximum concentrations during the 2010s in major urban agglomerations across China. The association between a long-term change in summer O₃ concentrations and LUC after excluding the effect of precursor emissions and meteorological conditions and causes of interannual (short-term) variations in O₃ concentrations induced by urban-land expansion were also explored by examining the relationships between ozone fluctuations and meteorological variables.

Mesoscale cycling of organophosphorus flame retardants (OPFRs) in the Bohai Sea and Yellow Sea biotic and abiotic environment: A WRF-CMAQ modeling

Rapid urbanization and industrialization in the eastern seaboard region of China enhance the widespread use of organophosphorus flame retardants (OPFRs). The present study set up a coupled WRF-CMAQ-SMOKE and multi-compartment exchange modeling framework to assess the environmental fate and cycling of OPFRs and their contamination in the Bohai and Yellow Seas' marine food web. The framework predicts meteorological conditions, optimized air emissions, and concentrations of OPFRs in air, seawaters, marine sediment, and the food web. The model was implemented to simulate the temporal and spatial fluctuations of Tris (2-chloroisopropyl) phosphate (TCPP), the most dominant congener of OPFRs in China, in the Bohai and the Yellow Sea ecosystems on a spatial resolution of 10 km. Results revealed the effects of source proximity, atmospheric transport and deposition, and the changes in meteorology on TCPP's temporal-spatial distribution across different areas of coastal waters. The model also captures TCPP levels in commercial fish species in the Bohai Sea. The detailed temporal-spatial characteristics of TCPP with the mesoscale resolution provide useful information and a new tool for the environmental and health consequences of mariculture, urban and industrial emission mitigation in coastal regions for emerging chemicals, and fishery industry development.

The footprint of dioxins in globally traded pork meat

The bioaccumulation of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs), known as dioxins, in fatty meat is one of primary pathways of entry into the human body, but levels of human exposure to dioxins in fatty meat subject to global trade are unknown. We show high dioxin estimated dietary intake (EDI) via pork consumption in Europe, the United States, and China, owing to stronger dioxin environmental contamination and high pork consumption in these countries. The dioxin risk transfer embodied in pork trade is mostly significant in high-latitude countries and regions of Canada, Russia, and Greenland because these regions with low dioxin environmental levels import large amounts of pork meat from more severely dioxin-contaminated Europe and the United States. We demonstrate that global pig feed trading decreases the exposure of pork consumers to dioxins via the import of feed from countries with low dioxin environmental contamination by pig breeding countries.

Multiscale Chirping Modes Driven by Thermal Ions in a Plasma with Reactor-Relevant Ion Temperature

A thermal ion driven bursting instability with rapid frequency chirping, considered as an Alfvénic ion temperature gradient mode, has been observed in plasmas having reactor-relevant temperature in the DIII-D tokamak. The modes are excited over a wide spatial range from macroscopic device size to microturbulence size and the perturbation energy propagates across multiple spatial scales. The radial mode structure is able to expand from local to global in ∼0.1  ms and it causes magnetic topology changes in the plasma edge, which can lead to a minor disruption event. Since the mode is typically observed in the high ion temperature ≳10  keV and high-β plasma regime, the manifestation of the mode in future reactors should be studied with development of mitigation strategies, if needed. This is the first observation of destabilization of the Alfvén continuum caused by the compressibility of ions with reactor-relevant ion temperature.

LncRNA ROR1-AS1 promotes colon cancer cell proliferation by suppressing the expression of DUSP5/CDKN1A

OBJECTIVE

The purpose of this study was to explore the possible role of ROR1-AS1 in the pathogenesis of colon cancer and the underlying mechanism.

PATIENTS AND METHODS

The expression levels of ROR1-AS1 in 75 colon cancer tissue samples and adjacent ones, as well as in cell lines were examined by quantitative Polymerase Chain Reaction (qPCR). Then, ROR1-AS1 overexpression plasmid and siRNA were transfected into colon cancer cells using liposome method. After that, Cell Counting Kit-8 (CCK-8) and plate colony formation assays were conducted to analyze cell proliferation, while flow cytometry was applied for the analysis of cell cycle and apoptosis. At last, the mechanism of action of ROR1-AS1 was further explored by nuclear separation, RNA binding protein immunoprecipitation (RIP) and chromatin immunoprecipitation (CHIP) assays.

RESULTS

ROR1-AS1 level in colon cancer tissues was remarkably higher than that in normal tissues, and the expression in tumors of stage III and IV was remarkably higher than those of stage I and II. Meanwhile, tumors with diameters more than 5 cm had a higher ROR1-AS1 expression than those less than 5 cm. After transfection with ROR1-AS1 overexpression plasmid, the cell proliferation ability was enhanced, the G0/G1 phase time of cell cycle was shortened, and the apoptosis was suppressed. However, the opposite result was observed after ROR1-AS1 was downregulated. Furthermore, RIP showed that ROR1-AS1 can bind to enhancer of zeste homolog 2 (EZH2) and inhibit the expression of DUSP5, and thus be engaged in the proliferation and apoptosis of colon cancer cells.

CONCLUSIONS

ROR1-AS1 is highly expressed either in colon cancer tissues or in cell lines, which is able to enhance cell proliferation, accelerate cell cycle, and inhibit cell apoptosis. The mechanism of ROR1-AS1 to participate in the development of colon cancer may be the downregulation of DUSP5 via combination with EZH2.

Isolation and characterization of ergosterol from Monascus anka for anti-lipid peroxidation properties

Unbalanced lipid peroxidation damages the human body, and is associated with the formation of tumors, infections, inflammations, autoimmune diseases, and cardiovascular and cerebrovascular diseases. However, food and drugs that contain anti-lipid peroxidation active substances, can help to protect against these negative health impacts. We observed lipid peroxidation inhibition in the metabolites of fermented Monascus anka, in media with Dendrobium nobile Lindl. The anti-lipid peroxidation ability of the extracts was strongest in ethyl acetate, so this was selected for further purifications. A crystal with strong antioxidant properties was obtained by column chromatography. Based on its spectroscopic analysis by Electron Bombardment Ion Source and Mass Spectrometry (EI-MS), ¹H-Nuclear Magnetic Resonance (¹H-NMR), and ¹³C-Nuclear Magnetic Resonance (¹³C-NMR), the isolated crystal was identified as ergosterol. The inhibition rates of the lipid peroxide due to the ergosterol were 57.42%, at 2μg/mL in vitro. Simultaneously, the survival rates of the damaged cells treated with 0.3mmol/L H₂O₂ were significantly improved with the ergosterol, up to 43.88% (200μg/mL) and 46.64% (400μg/mL), compared to 36.47% for the injured cells. The survival rate of the cells was 78.32% (400μg/mL), with ergosterol as a prevention. Cell injury can increase the level of intracellular ROS, but its levels in the damaged cells were reduced after the ergosterol treatments, and the reduction increased with the increasing concentrations. A 400μg/mL concentration resulted in the lowest fluorescence intensity; 33421.11 AU below the normal level. Ergosterol significantly reduced the ROS levels, to reduce the cell damage. Ergosterol from Monascus anka was thus found to have strong anti-lipid peroxidation and antioxidant capabilities, and the ability to protect and repair damaged cells. It may consequently serve as a potential natural antioxidant and will play an important role in human anti-lipid peroxide.

LINC01605 promotes the proliferation of laryngeal squamous cell carcinoma through targeting miR-493-3p

OBJECTIVE

The purpose of this study was to elucidate the potential influence of LINC01605 on the progression of laryngeal squamous cell carcinoma (LSCC) and the underlying mechanism.

PATIENTS AND METHODS

LINC01605 and microRNA-493-3p (miR-493-3p) levels in normal laryngeal tissues, LSCC tissues, and paired paracancerous tissues were detected. Regulatory effects of LINC01605 on proliferative ability and apoptosis in HEp-2 and AMC-HN-8 cells were assessed. Besides, the interaction between LINC01605 and miR-493-3p was evaluated by Dual-Luciferase reporter gene assay and Spearman's rank correlation analysis. Finally, rescue experiments were conducted to clarify the role of LINC01605/miR-493-3p axis in the progression of LSCC.

RESULTS

LINC01605 was upregulated and miR-493-3p was downregulated in LSCC tissues. Knockdown of LINC01605 inhibited proliferative ability, and stimulated apoptosis in HEp-2 and AMC-HN-8 cells. Moreover, LINC01605 directly bound to miR-493-3p, and the former negatively regulated the level of the latter. In addition, miR-493-3p was able to reverse the regulatory effect of LINC01605 on proliferative ability in LSCC.

CONCLUSIONS

LINC01605 is upregulated in LSCC tissues, and it promotes the malignant progression of LSCC via targeting miR-493-3p.

Simulation of the impact of the emergency control measures on the reduction of air pollutants: a case study of APEC blue

Serious air pollution motivates governments to take control measures. However, specific emission reduction effects of various temporary emission reduction policies are difficult to evaluate. During the Asia-Pacific Economic Cooperation meeting in Beijing in 2014, the Chinese government implemented a number of emergency emission control measures in the Beijing-Tianjin-Hebei area to maintain the air quality in this region. This gave us an opportunity to quantify the effectiveness of the emission reduction measures separately and identify the efficient policy combinations for the reduction of major pollutants. In this study, we evaluated the impacts of specific emission reduction measures on the concentrations of two major air pollutants (PM_2.5 and O₃) under eight policy scenarios using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). Comparing these scenarios, we found that the control policies against the primary PM_2.5 emission achieved the most significant results. Meanwhile, all the emission control measures raised the ozone concentrations in different degrees, which might be partly attributed to the changes of PM_2.5 concentration and the ratio of NO_x and VOCs caused by the emission control measures. Our results suggest that, in VOC-sensitive areas like Beijing, emergency control measures focusing on primary PM_2.5 emission could lead to significant PM_2.5 reduction and relatively small ozone increase, and should be considered as a priority policy. Joint emission control at the regional scale is also important especially under unfavorable meteorological conditions.

Role of Microtearing Turbulence in DIII-D High Bootstrap Current Fraction Plasmas

We report on the first direct comparisons of microtearing turbulence simulations to experimental measurements in a representative high bootstrap current fraction (f_{BS}) plasma. Previous studies of high f_{BS} plasmas carried out in DIII-D with large radius internal transport barriers (ITBs) have found that, while the ion energy transport is accurately reproduced by neoclassical theory, the electron transport remains anomalous and not well described by existing quasilinear transport models. A key feature of these plasmas is the large value of the normalized pressure gradient, which is shown to completely stabilize conventional drift-wave and kinetic ballooning mode instabilities in the ITB, but destabilizes the microtearing mode. Nonlinear gyrokinetic simulations of the ITB region performed with the cgyro code demonstrate that the microtearing modes are robustly unstable and capable of driving electron energy transport levels comparable to experimental levels for input parameters consistent with the experimental measurements. These simulations uniformly predict that the microtearing mode fluctuation and flux spectra extend to significantly shorter wavelengths than the range of linear instability, representing significantly different nonlinear dynamics and saturation mechanisms than conventional drift-wave turbulence, which is also consistent with the fundamental tearing nature of the instability. The predicted transport levels are found to be most sensitive to the magnetic shear, rather than the temperature gradients more typically identified as driving turbulent plasma transport.

Breast cancer Ki67 expression prediction by DCE-MRI radiomics features

AIM

To investigate whether quantitative radiomics features extracted from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) are associated with Ki67 expression of breast cancer.

MATERIALS AND METHODS

This institutional review board-approved retrospective study comprised 377 Chinese women who were diagnosed with invasive breast cancer in 2015. This cohort included 53 low-Ki67 expression (Ki67 proliferation index less than 14%) and 324 cases with high-Ki67 expression (Ki67 proliferation index more than 14%). A binary-classification of low-versus high- Ki67 expression was performed. A set of 56 quantitative radiomics features, including morphological, greyscale statistic, and texture features, were extracted from the segmented lesion area. Three machine learning classification methods, including naive Bayes, k-nearest neighbour and support vector machine, were employed for the classification and the least absolute shrink age and selection operator (LASSO) method was used to select most predictive features set for the classifiers. Classification performance was evaluated by the area under receiver operating characteristic curve (AUC), accuracy, sensitivity, and specificity.

RESULES

The model that used naive Bayes classification method achieved the best performance than the other two methods, yielding 0.773 AUC, 0.757 accuracy, 0.777 sensitivity and 0.769 specificity. Three most predictive features, i.e., contrast, entropy and line likeness, were selected by the LASSO method and showed a statistical significance (p<0.05) in the classification.

CONCLUSION

The present study showed that quantitative radiomics imaging features of breast tumour extracted from DCE-MRI are associated with breast cancer Ki67 expression. Future larger studies are needed in order to further evaluate the findings.

The effects of a sodium-glucose cotransporter 2 inhibitor on diabetic nephropathy and serum oxidized low-density lipoprotein levels

OBJECTIVE

To investigate the effect of an SGLT-2 inhibitor on diabetic nephropathy and serum oxidized low-density lipoprotein (ox-LDL) levels.

PATIENTS AND METHODS

We randomly divided 126 patients with diabetic nephropathy into the treatment group and control group. The 63 patients in the treatment group received an SGLT-2 inhibitor in addition to routine insulin therapy, while the control group received only insulin to control blood glucose. All laboratory indexes were recorded before and after treatment with the SGLT-2 inhibitor. The prognosis of patients was followed-up. Simultaneously, 63 healthy and BMI-matched in-patients were selected as the healthy control group. Peripheral blood samples were collected from all groups, and the levels of ROS were measured by ELISA.

RESULTS

Renal function indexes such as urinary protein, creatinine, blood urea nitrogen, and glomerular filtration rate (GFR) were significantly higher with SGLT-2 inhibitor treatment compared with the control group (p<0.05). The fasting blood glucose level was not significantly increased before or after treatment (p>0.05). The levels of ROS in peripheral blood were significantly lower in the treatment group than in the control group (p<0.05). Observation at the 1-year follow-up showed that the average GFR was significantly higher in the treatment group than in the control group. Furthermore, the proportion of patients with stage 1-3 chronic kidney disease was significantly higher in the treatment group than in the control group (p<0.05).

CONCLUSIONS

The SGLT-2 inhibitor had a good therapeutic effect on renal function in patients with diabetic nephropathy, without having effects on fasting blood glucose. Additionally, it significantly delayed the progression of nephropathy. It is therefore worth clinical promotion.

High resolution polarimeter-interferometer system for fast equilibrium dynamics and MHD instability studies on Joint-TEXT tokamak (invited)

A high-performance Faraday-effect polarimeter-interferometer system has been developed for the J-TEXT tokamak. This system has time response up to 1 μs, phase resolution < 0.1° and minimum spatial resolution ∼15 mm. High resolution permits investigation of fast equilibrium dynamics as well as magnetic and density perturbations associated with intrinsic Magneto-Hydro-Dynamic (MHD) instabilities and external coil-induced Resonant Magnetic Perturbations (RMP). The 3-wave technique, in which the line-integrated Faraday angle and electron density are measured simultaneously by three laser beams with specific polarizations and frequency offsets, is used. In order to achieve optimum resolution, three frequency-stabilized HCOOH lasers (694 GHz, >35 mW per cavity) and sensitive Planar Schottky Diode mixers are used, providing stable intermediate-frequency signals (0.5-3 MHz) with S/N > 50. The collinear R- and L-wave probe beams, which propagate through the plasma poloidal cross section (a = 0.25-0.27 m) vertically, are expanded using parabolic mirrors to cover the entire plasma column. Sources of systematic errors, e.g., stemming from mechanical vibration, beam non-collinearity, and beam polarization distortion are individually examined and minimized to ensure measurement accuracy. Simultaneous density and Faraday measurements have been successfully achieved for 14 chords. Based on measurements, temporal evolution of safety factor profile, current density profile, and electron density profile are resolved. Core magnetic and density perturbations associated with MHD tearing instabilities are clearly detected. Effects of non-axisymmetric 3D RMP in ohmically heated plasmas are directly observed by polarimetry for the first time.

Equilibrium reconstruction based on core magnetic measurement and its applications on equilibrium transition in Joint-TEXT tokamak

Evaluation and reconstruction of plasma equilibrium, especially to resolve the safety factor profile, is imperative for advanced tokamak operation and physics study. Based on core magnetic measurement by the high resolution laser polarimeter-interferometer system (POLARIS), the equilibrium of Joint-TEXT (J-TEXT) plasma is reconstructed and profiles of safety factor, current density, and electron density are, therefore, obtained with high accuracy and temporal resolution. The equilibrium reconstruction procedure determines the equilibrium flux surfaces essentially from the data of POLARIS. Refraction of laser probe beam, a major error source of the reconstruction, has been considered and corrected, which leads to improvement of accuracy more than 10%. The error of reconstruction has been systematically assessed with consideration of realistic diagnostic performance and scrape-off layer region of plasma, and its accuracy has been verified. Fast equilibrium transitions both within a single sawtooth cycle and during the penetration of resonant magnetic perturbation have been investigated.

Multiple logistic regression analysis of risk factors for carcinogenesis of oral submucous fibrosis in mainland China

Oral submucous fibrosis (OSF), a chronic progressive disorder, is regarded as the premalignant lesion of oral squamous cell carcinoma (OSCC). Its distribution is associated with chewing betel quid (BQ). The objective of the present study was to investigate risk factors for the carcinogenesis of OSF in mainland China. A case-control study was performed in 42 patients with OSCC that originated from OSF and 40 OSF controls. Epidemiological data and information related to risk factors were collected using a short structured questionnaire. Odd ratios (OR) and 95% confidence intervals (CI) were derived from logistic regression analysis. In multivariate analysis, only age, duration of BQ chewing, duration of cigarette smoking, and OSF accompanied by oral leukoplakia or oral lichen planus were associated with significantly increased risk for the malignant transformation of OSF. These findings contribute to current knowledge on the prevention of carcinogenesis of OSF in mainland China.

FDTD Simulation of Nonlinear Ultrasonic Pulse Propagation in ESWL

The extracorporeal shock wave lithotripsy (ESWL) has come into wide use due to its non-invasive advantage. However, as for the shock wave propagation in human body in relation to practical lithotripsy, there are a few studies on numerical simulation based on models conforming to practical situations. In this paper we report a numerical method of finite difference time domain (FDTD) for analyzing ultrasonic pulse nonlinear propagation in human body tissues and demonstrated it through an experiment of Reichenberger's ESWL in water.

Pulsed Rayleigh wave scattered at a surface crack

This paper investigates Rayleigh wave interaction with machined slots on flat aluminium blocks to simulate surface breaking cracks. Using a finite element method, Rayleigh wave scattering by narrow slots of varied depth ranging from 0.5 mm to 20 mm is calculated. Pulsed wideband Rayleigh waves with a centre frequency of 590 kHz and -6 dB bandwidth of 520 kHz is considered. Reflection and transmission coefficients are calculated and compare well with the published literature. We and other workers have reported enhancement of the measured amplitude or particle velocity of an apparent Rayleigh wave close to a surface defect. In this paper, it is found that the predicted enhancement of in-plane components of particle velocities close to a crack is significantly higher than that of the out-of-plane components of particle velocities which appears to be mainly due to the mode-converted surface skimming longitudinal wave from the crack that has mainly in-plane components near the sample surface. The enhancement of the in-plane particle velocity will be observed regardless of the type of in-plane sensitive ultrasonic detector used. The explanation of the discrepancy of the reflection and transmission coefficients obtained by pulsed and narrow band or pseudo continuous Rayleigh waves is discussed. The later-arriving Rayleigh waves from reverberation along the inside of the crack surface are observed, as has been previously reported by other workers, and this may also be used to gauge slot depth.

Depth gauging of defects using low frequency wideband Rayleigh waves

In non-destructive testing for cracks it is not sufficient to simply detect the presence of a defect, but it is essential to have an accurate measure of the depth. Accurate calibration of the techniques used to gauge defect size is therefore necessary. Recent progress in the field of non-contact ultrasonic testing has led to the development of a practically viable system for generating and detecting wideband Rayleigh waves on electrically conducting or magnetic samples using electro-magnetic acoustic transducers (EMATs). This system has been used to gauge the depth and position of surface breaking defects, and has many applications including metal billet testing and detecting and sizing gauge corner cracking in rails. In this paper we report experiments calibrating the response of EMATs when a defect is present between the generator and receiver, using a calibration sample with slots machined perpendicular to the surface to simulate surface breaking cracks. The depth of the defect can be gauged in the time domain and frequency domain, with an accurate 'fingerprint' of the position given by an enhancement of the signal when the receiver is close to the defect. The best choice of EMAT design for different applications is discussed, as is the best position for the receive EMAT to avoid areas of interference between the Rayleigh wave and bulk waves diffracted from the crack tip.

Gbetagamma affinity for bovine rhodopsin is determined by the carboxyl-terminal sequences of the gamma subunit

Two native betagamma dimers, beta(1)gamma(1) and beta(1)gamma(2), display very different affinities for receptors. Since these gamma subunits differ in both primary structure and isoprenoid modification, we examined the relative contributions of each to Gbetagamma interaction with receptors. We constructed baculoviruses encoding gamma(1) and gamma(2) subunits with altered CAAX (where A is an aliphatic amino acid) motifs to direct alternate or no prenylation of the gamma chains and a set of gamma(1) and gamma(2) chimeras with the gamma(2) CAAX motif at the carboxyl terminus. All the gamma constructs coexpressed with beta(1) in Sf9 cells yielded beta(1)gamma dimers, which were purified to near homogeneity, and their affinities for receptors and Galpha were quantitatively determined. Whereas alteration of the isoprenoid of gamma(1) from farnesyl to geranylgeranyl and of gamma(2) from geranylgeranyl to farnesyl had no impact on the affinities of beta(1)gamma dimers for Galpha(t), the non-prenylated beta(1)gamma(2) dimer had significantly diminished affinity. Altered prenylation resulted in a <2-fold decrease in affinity of the beta(1)gamma(2) dimer for rhodopsin and a <3-fold change for the beta(1)gamma(1) dimer. In each case with identical isoprenylation, the beta(1)gamma(2) dimer displayed significantly greater affinity for rhodopsin compared with the beta(1)gamma(1) dimer. Furthermore, dimers containing chimeric Ggamma chains with identical geranylgeranyl modification displayed rhodopsin affinities largely determined by the carboxyl-terminal one-third of the protein. These results indicate that isoprenoid modification of the Ggamma subunit is essential for binding to both Galpha and receptors. The isoprenoid type influences the binding affinity for receptors, but not for Galpha. Finally, the primary structure of the Ggamma subunit provides a major contribution to receptor binding of Gbetagamma, with the carboxyl-terminal sequence conferring receptor selectivity.

Independent and synergistic interaction of retinal G-protein subunits with bovine rhodopsin measured by surface plasmon resonance

We have used surface plasmon resonance (SPR) measurements for the kinetic analysis of G-protein-receptor interaction monitored in real time. Functionally active rhodopsin was immobilized on an SPR surface, with full retention of biochemical specific activity for catalysis of nucleotide exchange on the retinal G-protein alpha subunit, via binding to immobilized concanavalin A. The binding interactions of bovine retinal alpha(t) and beta(1)gamma(1) subunits with rhodopsin measured by SPR were profoundly synergistic. Synergistic binding of the retinal G-protein subunits to rhodopsin was not observed for guanosine 5'-[gamma-thio]triphosphate-bound Galpha(t), nor was binding observed with squid retinal Galpha(q), which is not activated by bovine rhodopsin. The binding affinity (336+/-171 nM; mean value+/-S.D.) of retinal betagamma for rhodopsin in the presence of retinal alpha subunit measured by SPR confirmed the apparent affinity of 254 nM determined previously by nucleotide exchange assays. Binding of beta(1)gamma(1), beta(1)gamma(2), and beta(1)gamma(8-olf) dimers to rhodopsin, independently of the alpha subunit, was readily observable by SPR. Further, these dimers, differing only in their gamma subunit compositions, displayed markedly distinct binding affinities and kinetics. The beta(1)gamma(2) dimer bound with a kinetically determined K(d) of 13+/-3 nM, a value nearly identical with the biochemically determined K(1/2) of 10 nM. The physiologically appropriate beta(1)gamma(1) displayed rapid association and dissociation kinetics, whereas the other beta(1)gamma dimers dissociated at a rate less than 1/100 as fast. Thus rhodopsin interaction with its native signalling partners is both rapid and transient, whereas the interaction of rhodopsin with heterologous Gbetagamma dimers is markedly prolonged. These results suggest that the duration of a G-protein-coupled receptor signalling event is an intrinsic property of the G-protein coupling partners; in particular, the betagamma dimer.

Two amino acids in the sixth transmembrane segment of the mouse gastrin-releasing peptide receptor are important for receptor activation

The gastrin-releasing peptide receptor (GRP-R) is a G protein-coupled receptor that mediates a variety of cellular responses, including cell growth and modulation of neuronal activity by activation of heterotrimeric GTP-binding proteins in the Gq family. To understand the regulation of GRP-R signaling we have substituted alanine for each of 10 amino acid residues within the transmembrane (TM) helices of the GRP-R predicted to project into the binding pocket of the receptor and analyzed the importance of each of these residues for receptor function. Two mutations showed selective loss of either agonist (Y285A) or antagonist (F313A) affinity for the GRP-R. In addition, we identified two amino acid residues, Phe(270) and Asn(281), in the sixth TM segment, which are important for receptor-G protein interaction. In a competition-binding assay with an antagonist radioligand, bombesin showed a 20- to 100-fold decreased affinity for the N281A and F270A mutant GRP-R compared with wild-type GRP-R. The saturation-binding isotherms are best fit by a two-state model, indicating that the receptors are in either a low-affinity (K(D2)) or a high-affinity (K(D1)) state. The ratio of the two affinities (K(D2)/K(D1)) was significantly increased for both mutants compared with wild-type GRP-R, whereas the fraction of mutant receptors in the high-affinity state (R(1)) was decreased. GDP/guanosine-5'-O-(3-thio)triphosphate exchange catalyzed by the N281A mutant was lower than that observed for the wild-type GRP-R. However, for both mutants, bombesin was still able to stimulate 1,4,5-inositol triphosphate in transfected cells albeit with reduced activity. We conclude that these two TM residues are important for receptor-G protein coupling, and postulate that each mutation may affect GRP-R conformational change to the high-affinity, G protein-coupled state.

Phosphorylation uncouples the gastrin-releasing peptide receptor from G(q)

Previous work on the desensitization of G protein-coupled receptors has focused on the role of arrestin binding following receptor phosphorylation. We have examined the hypothesis that phosphorylation alone contributes to desensitization. In this study we demonstrate that for the G(q)-coupled gastrin-releasing peptide receptor (GRP-R), phosphorylation by GRK2 to a stoichiometry of approximately 1 mol PO(4)/mol GRP-R is sufficient in the absence of arrestin to reduce the rate of receptor catalyzed G protein activation by approximately 80%. Furthermore, GRP-Rs exposed in vivo to agonist are rapidly phosphorylated to a similar stoichiometry and are desensitized to a similar degree. Finally, the molecular mechanism for both in vitro GRK2-induced and in vivo agonist-induced desensitization is primarily a decrease in the maximum velocity (V(max)) for the catalysis of guanine nucleotide exchange by the GRP-R rather than a change in the affinity of the receptor for the alpha(q) or betagamma subunits. Based on these results, we suggest that, for some G protein-coupled receptors, phosphorylation has a role in desensitization that is independent of arrestin.

[Construction of expressing vector for phage display scFv and a mouse unspecified antibody library]

The display of antibody gene library on the surface of E. coli filamentous phage offers a new method of obtaining antibodies against specific antigens. In the paper, it is reported that a phagemid for phage display antibody, named after pFUW80, characterized expressing scFv either secretly or stickily. With a series of designed PCR primers, heavy-chain and light-chain variable region genes of mice antibodies were amplified and a mouse unspecified single-chain antibody library with the size of 1.2 x 10(6) clones was constructed. From this library, phage was selected out against antigen human IgG and detected by ELISA and partial sequence analysis. These primary results established the foundation for future research using this system.

The bombesin receptor subtypes have distinct G protein specificities

We used an in situ reconstitution assay to examine the receptor coupling to purified G protein alpha subunits by the bombesin receptor family, including gastrin-releasing peptide receptor (GRP-R), neuromedin B receptor (NMB-R), and bombesin receptor subtype 3 (BRS-3). Cells expressing GRP-R or NMB-R catalyzed the activation of squid retinal Galphaq and mouse Galphaq but not bovine retinal Galphat or bovine brain Galphai/o. The GRP-R- and NMB-R-catalyzed activations of Galphaq were dependent upon and enhanced by different betagamma dimers in the same rank order as follows: bovine brain betagamma > beta1gamma2 >> beta1gamma1. Despite these qualitative similarities, GRP-R and NMB-R had distinct kinetic properties in receptor-G protein coupling. GRP-R had higher affinities for bovine brain betagamma, beta1gamma1, and beta1gamma2 and squid retinal Galphaq. In addition, GRP-R showed higher catalytic activity on squid Galphaq. Like GRP-R and NMB-R, BRS-3 did not catalyze GTPgammaS binding to Galphai/o or Galphat. However, BRS-3 showed little, if any, coupling with squid Galphaq but clearly activated mouse Galphaq. GRP-R and NMB-R catalyzed GTPgammaS binding to both squid and mouse Galphaq, with GRP-R activating squid Galphaq more effectively, and NMB-R also showed slight preference for squid Galphaq. These studies reveal that the structurally similar bombesin receptor subtypes, in particular BRS-3, possess distinct coupling preferences among members of the Galphaq family.

[Clinic analysis of surgical treatment for benign parotid tumour 55 cases]

OBJECTIVE

To investigate the relationship between 3 kinds of surgical methods and the postoperative recurrence and complication of patients with the benign parotid tumours.

METHOD

The records of benign parotid tumours cases (55 patients), who were treated in 1987-1997 at our hospital, were retrospectively analysed. The operative methods as follows: local excision (20 patients), superficial parotidectomy (28 patients), total parotidectomy (7 patients), facial nerve was anatomied during operation for 35 patients.

RESULT

The rate of tumour recurrence, partial facial nerve paralysis, parotid gland fistula and Frey's syndroms after operation were 14.6% (8/55), 14.6% (8/55), 7.3% (4/55) and 7.3% (4/55) respectively.

CONCLUSION

The operation of superficial parotidectomy or total parotidectomy should be perfromed for benign parotid tumour cases, facial nerve should be anatomied during operation, for reducing tumour recurrence and facial nerve paralysis.

[Morphologic characteristics of dental cuticle on teeth affected by diabetic periodontitis]

OBJECTIVE

To determine the nature of the dental cuticle found on teeth with diabetic periodontitis.

METHODS

Thirteen permanent teeth which were extracted from three diabetic patients with periodontitis were studied, with the control group of 16 healthy teeth extracted for orthodontical reasons, then all the teeth were decalcified with 5% nitric acid, stained with HE, and examinated by using light microscope.

RESULTS

A layer of thick coat, dental cuticle, covered the root surface of the teeth with diabetic periodontitis, and the cuticle which presented regular laminar structure extended from the cementoenamel junction to the apical portion with different thickness from 40 to 80 microns, but no such similar cuticle structure was found on the healthy teeth of the control group.

CONCLUSION

There is abnormal cuticle structure on the teeth of diabetic patients with periodontitis.

[The preventing function of garlic on experimental oral precancer and its effect on natural killer cells, T-lymphocytes and interleukin-2]

In order to study the effect and mechanism of garlic on preventing oral precancer, we divided randomly 32 Wistar rats into two groups. The garlic group was painted with garlic solution on the hard palatal mucosae. The control group was applied with distilled water that is equal in quantity. Then, chemical carinogen 4-nitroquinoline 1-oxide (4NQO) was painted on the same sites for both groups, three times weekly. Eight rats were randomly killed in the 10th, 13th week. The hard palatal mucosae were examined with light microscope. Meanwhile, lymphocytes were isolated from the rat spleens. The activation of natural killer (NK) cells and T-lymphocytes, and level of interleukin-2 were determined by radioimmunoassay. The results revealed that garlic effectively prevented oral precancer induced by 4NQO. This effect may be related to the following factors that garlic can improve the activation of NK cells, the function of T-lymphocytes, and the level of IL-2.

[A study of anaerobic infection in maxillofacial region]

To analyse the anaerobic infection of maxillofacial surgery and estimate the efficacy of antianaerobic therapy, 45 patients were divided into two groups, tinidazole group and metronidazole group. Bacterial culture was positive before treating in all cases. There were Bacillus Melaniogenicus, Veillonella, Peptococcus and Peptostreptococus, etc. There was excellent efficacy in the treatment of maxillofacial anaerobic infection by tinidazole intravenously. After treatment, the result of bacterial examination was negative. The healing rate was 96.4% in 28 cases which used tinidazol, but 82.4% in control group which used metronidazole. The value of white blood cell and the function of liver and kidney pro- and post-treatment were not significantly different (P < 0.05) by comparision.

Myosin light chain kinase: expression in neurons and upregulation during axon regeneration

Myosin light-chain kinase (MLCK) regulates actin-myosin II interactions in nonskeletal muscle cells, and the use of specific pharmacological inhibitors has implicated MLCK in retinal growth cone motility and neurite outgrowth. To further establish the existence and functions of MLCK in neurons, we isolated cDNAs encoding two forms of goldfish MLCK that were differentially expressed in the brain and gut and we sequenced the form most abundantly expressed in the brain (GFMLCK1). In situ hybridization with a cRNA probe specific to GFMLCK1 revealed widespread expression in CNS neurons, including tectal periventricular neurons and cerebellar and medullary neurons. After optic nerve crush, expression was markedly increased in the retinal ganglion cells. Expression peaked during the phase of axonal outgrowth, which, when taken together with our previous pharmacological studies, further supports a role for MLCK in growth cone motility.

[Surgical treatment of unilateral alveolar cleft]

In this study, 16 cases of unilateral alveolar cleft with cleft lip and palate were repaired with autografts of cancellous bone (13 cases) or hydroxyapatite (3 cases). The grafts were covered by reflected mucoperiosteal flaps and a mucosal flap from the upper lip. Twelve of the thirteen cases were followed up for 1-5 years. Nine of whom using cancellous bone had bony continuity of the maxilla and 7 cases erupted permanent maxillary canines within the area of autografts. None of the 3 cases using hydroxyapatite erupted a canine tooth. The results showed that autograft was better than hydroxyapatite in terms of maxillary canine eruption.

Changes in distribution of labile zinc in mouse spermatozoa during maturation in the epididymis assessed by the fluorophore Zinquin

The Zn(II)-specific fluorophore Zinquin was used to determine the regional distribution of free or loosely-bound Zn(II) in mouse spermatozoa. Spermatozoa from the testes exhibited bright fluorescence over the entire head; those from the caput epididymides generally fluoresced more brightly in the post-acrosomal region; and spermatozoa from the caudae epididymides fluoresced less brightly, with foci of fluorescence over the sperm head which were lost after extraction with Triton X-100 and hence appeared to be membrane-associated. Treatment of cauda sperm with sodium dodecyl sulfate resulted in a bright uniform Zinquin fluorescence in the heads, similar to that observed in caput sperm, indicating that the two types of sperm have similar amounts of head Zn(II) but that the availability of Zn(II) for binding Zinquin is different. By contrast, the intensity of tail fluorescence was similar in spermatozoa from different regions of the male reproductive tract and was largely unaffected by Triton X-100 extraction, consistent with an intracellular location. Similar differences were observed between caput sperm and cauda sperm in the rat. It is concluded that visualization and measurement of free or loosely-bound Zn(II) in subcellular compartments of spermatozoa should facilitate investigation of the role of this metal in the development and function of spermatozoa and abnormalities that might accompany infertility and Zn(II) deficiency.

Kinase requirement for retinal growth cone motility

Since cytoplasmic Ca2+ levels are reported to regulate neurite elongation, we tested whether calcium-activated kinases might be necessary for growth cone motility and neurite elongation in explant cultures of goldfish retina. Kinase inhibitors and activators were locally applied by micropipette to retinal growth cones and the responses were observed via phase-contrast videomicroscopy. In some cases, growth rates were also quantified over several hours after general application in the medium. The selective inhibitors of protein kinase C, calphostin C (0.1-1 microM) and chelerythrin (up to 50 microM), caused no obvious changes in growth cones or neurite elongation, and activators of PKC (phorbols, arachidonic acid, and diacylglycerol) also were generally without effects, although phorbols slowed the growth rate. Inhibitors of protein kinase A and tyrosine kinases also produced no obvious effects. The calmodulin antagonists, calmidazolium (0.1 microM), trifluoperazine (100 microM), and CGS9343B (50 microM), however, caused a reversible growth cone arrest with loss of filopodia and lamellipodia. The growth cone became a club-shaped swelling which sometimes moved a short distance back the shaft, leaving evacuated filaments at points of strong filopodial attachments. A similar reversible growth cone arrest occurred with the general kinase inhibitors: H7 at 200 but not at 100 microM, and staurosporine at 100 but not 10 nM, suggesting possible involvement of a calmodulin-dependent kinase (camK) rather than PKC. The selective inhibitor of camKII, KN-62 (tested up to 50 microM), produced no effects, but the specific myosin light-chain kinase (MLCK) inhibitors ML-7 (3-5 microM) and ML-9 (5-10 microM) reversibly reproduced the effect, suggesting that MLCK rather than camKII is necessary for growth cone motility. The MLCK inhibitors' effects both on growth cone morphology and on F-actin filaments (rhodamine-phalloidin staining) were similar to those caused by cytochalasin D (5 microM), and are discussed in light of findings that inhibiting MLCK disrupts actin filaments in astrocytes and fibroblasts.