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At present, the risk factors of cervical lymph node metastasis (LNM) in papillary thyroid carcinoma (PTC) are still controversial. This study was aimed to investigate the risk factors of various types of LNM in PTC with tumor diameter>1 cm. The clinical data of 2216 PTC patients were retrospectively analyzed. Univariate and multivariate logistic regression models were used to analyze the risk factors of LNM. In addition, the receiver operator characteristic (ROC) curve was used to find the best cut-off value of CLNM for predicting LLNM. Finally, the independent risk factors of LLNM were used to construct the prediction of LLNM nomogram. Age≤55 years old, male, bilateral lobe tumors, ETE, 2–3 cm tumor diameters, and fasting plasma glucose (FPG) were independent risk factors for CLNM. The ROC curve showed that the best cut-off value was 2.5. Age, male, bilateral lobe tumors, tumor diameters≥2 cm and CLNM≥3 were significantly associated with LLNM , while CLNM=1 or 2 was a protective factor for LLNM. Only tumor diameters≥3 cm was significantly associated with skip LLNM. The nomogram model (C-index=0.745) can be used to predict LLNM in PTC patients and guide the clinical selection of appropriate treatment options. Patients with high risk factors should undergo prophylactic lymph node dissection. The nomogram we established has a good predictive ability for LLNM, and for high-risk groups, it is necessary to actively perform prophylactic lateral lymph node dissection.

Objective To explore the multiple specific biomarkers and cognitive compensatory mechanisms of mild traumatic brain injury (mTBI) patients at recovery stage. Methods The experiment was performed in two sections. In Section I, using event-related potential, event-related oscillation and spatial phase-synchronization, we explored neural dynamics in 24 volunteered healthy controls (HC) and 38 patients at least 6 months post-mTBI (19 with epidural hematoma, EDH; 19 with subdural hematoma, SDH) during a Go/NoGo task. In Section II, according to the neuropsychological scales, patients were divided into sub-groups to assess these electroencephalography (EEG) indicators in identifying different rehabilitation outcomes of mTBI. Results In Section I, mean amplitudes of NoGo-P3 and P3d were decreased in mTBI patients relative to HC, and NoGo-theta power in the non-injured hemisphere was decreased in SDH patients only. In Section II, patients with chronic neuropsychological defects exhibited more serious impairments of intra-hemispheric connectivity, whereas inter-hemispheric centro-parietal and frontal connectivity were enhanced in response to lesions. Conclusions EEG distinguished mTBI patients from healthy controls, and estimated different rehabilitation outcomes of mTBI. The centro-parietal and frontal connectivity are the main compensatory mechanism for the recovery of mTBI patients. Significance EEG measurements and network connectivity can track recovery process and mechanism of mTBI.

A growing number of studies have found a close association between thyroid hormones and thyrotrophin (TSH), and they also have prognostic significance in some cancer types; this study aimed to investigate the prognostic value of free triiodothyronine (fT3), free thyroxine (fT4), fT3/fT4, TSH, and their combination in patients with papillary thyroid carcinoma (PTC).This study retrospectively analyzed the relevant data of 726 newly diagnosed PTC patients. Both univariate and multivariate analyses were used to predict the recurrence rate, and a risk score was established. In addition, with the use of a random survival forest, a random forest (RF) score was constructed. After calculating the area under the curve (AUC), the diagnostic efficacy of risk score, RF score, and four indicators was compared.fT3, fT4, fT3/fT4, and TSH were strongly associated with some invasive clinicopathological features and postoperative recurrence. Patients with high expression of fT4 and TSH have a high risk of recurrence. By contrast, patients with high expression of fT3 and fT3/fT4 have a low risk of recurrence. At the same time, the combined use of various indicators is more helpful for establishing an accurate diagnosis. By comparison, we found that the RF score was better than the risk score in terms of predicting the recurrence of PTC.The diagnostic accuracy of a combination of fT3, fT4, fT3/fT4, and TSH can help improve our clinical estimate of the risk of recurrent PTC, thus allowing the development of a more effective treatment plan for patients.

In ultra HVDC transmission system, arcing horn gap breakdown makes the arc hard to extinguish, threatening transmission safety. Multi-chamber arrester (MCA) is applied in extinguishing the arc to ensure safety. Here, we investigated the arc motion characteristics of the MCA to analyze its arc extinguishing ability. First, a three-dimensional model of the arc plasma in a single chamber was established based on magneto-hydrodynamic (MHD) theory, and the arc motion inside and outside the chamber were analyzed. Next, changes of temperature, velocity and pressure field were simulated. The results showed that the time required for arc totally exiting the chamber is approximately $96~\mu \text{s}$ , the airflow maximun velocity is about 865 m/s, and the highest pressure is more than 4 atm. Particularly, there is a flow reflux at the outlet, as the air flows inward from the outside and form an “oscillation”. Moreover, the arc motion characteristics of different discharge currents within different chamber structure were analyzed. It was found that the spacing between anode and cathode, the radius of electrodes and the outlet radius are the key factors regulating the airflow velocity, and the outlet radius of the chamber has the greatest influence. At last, the accuracy of our model was validated with experimental data.

The strong airflow generated during the operation of the high-speed train will carry sand and dust, causing high-speed sand and dust to hit the surface of the external equipment of the vehicle body, which will increase the surface roughness of the roof insulators, resulting in the changes of the hydrophobicity, fouling characteristics and insulation performance of the insulator. It poses a hidden danger to the safe and stable operation of the train. In our existing surface roughness testing methods, contact detections and optical stylus methods can cause damage to the insulator surface. Infrared detection methods will be disturbed by leakage current. Most methods need to be disassembled for testing. These methods have certain disadvantages. Therefore, this paper proposes a non-contact detection method for the surface roughness of the roof insulators. Firstly, we extract the image information of the insulator surface by hyperspectral imager, then preprocess the extracted hyperspectral image and use the continuous projection algorithm to reduce the data. Finally, we use the support vector machine to construct the insulator surface roughness discriminant model, and successfully realize the hyperspectral detection method of the surface roughness of the roof insulators, and verify the effectiveness of the proposed method by experiments. As a non-contact detection method, this method can detect the surface roughness of the roof insulators in the non-disassembly conditions, and help the field staffs to grasp the surface roughness of the high-speed train roof insulators in time.

The stacked single-unit cell Ba1-xSrxTiO3 (BSTO) thin film designed by the high-throughput method is fabricated by layer-by-layer deposition by laser molecular beam epitaxy, and its ferroelectric and dielectric characteristics as a function of Sr concentration are comprehensively investigated. The permittivity of BSTO exhibits a monotonous increase by Sr with a plateau in the region of 14% < Sr < 85%. Meanwhile, at the low Sr doping regime, the piezoelectric response has been discovered, and the maximum piezoresponse and d33 can reach approximately 139.05 pm and 88 pm/V once an appropriate Ba/Sr ratio is formed, exhibiting a coexistence of a dielectric property and giant piezoresponse. This effective piezoelectric constant d33 value is significantly larger than the conventional chemical doping scenarios, suggesting that the intra-plane interaction is crucial for designing future promising dielectric and ferroelectric thin films via high-throughput technologies.

Using an artificial wind tunnel, the three basic preconditions presented in the preceding article by Kang et al are experimentally verified and systematically analyzed. The experimental results confirm that, in a discharge of flowing air, the breakdown path of an air gap deflects at an angle along the direction of the airflow. Some of electrons and ions are blown away by the airflow, and the mean free path of electron increases with increasing airflow velocity. In addition, the physical essences of the effects of flowing air on the discharge are revealed, and the differences in flowing air discharge between the uniform and non-uniform electric fields are discussed.

A physical model of flowing gas discharge is presented. This model extends Townsend's discharge model for static gases to flowing gases and can be applied to a wider range of gas discharge situations and the breakdown laws of flowing gases are analytically solved. The process of modeling reveals that the discharge of flowing gases includes three basic characteristics: the deflection of the major discharge path, the blowing away of some of electrons, and a decrease in gas density. The presented model enables quantitative calculations of the ionization coefficient and breakdown voltage in flowing gases. Comparisons between the present results and the corresponding ones obtained experimentally show good consistency. These results supplement the theory of gas discharge and provide some support for insulation protection in flowing gases.

The corrosion status of transmission line towers is difficult to detect. Once corrosion damage occurs, it will not only cause equipment and facilities to fail prematurely, be scrapped, and shorten their lifespan, but also cause significant economic losses, and even cause serious personal injuries. Traditional detection methods such as weightlessness method need to destroy the material structure, which is cumbersome to operate on site. This paper proposes a non-contact identification method based on hyperspectral technology for carbon steel corrosion grade of transmission towers. Collect hyperspectral images of carbon steel samples of different corrosion grades, use the pre-processed full-band spectral data to establish the K-nearest neighbor algorithm (KNN) model and the partial least squares discriminant analysis (PLS-DA) model. It is found through comparison that PLS-DA model classification effect is better. Through competitive adaptive reweighted sampling algorithm (CARS) and principal component analysis (PCA), the full-band spectral data of different corrosion grade carbon steel samples were extracted, and a PLS-DA model based on the optimal band was established. The results show that the use of characteristic waveband modeling greatly reduces the interference of redundant information, and the classification accuracy is better than that of the full waveband. The PLS-DA model based on the characteristic waveband has an accuracy of 95% for the classification of different corrosion levels in the verification set. Therefore, this method can be applied to the non-destructive and rapid detection of the corrosion level of carbon steel, and provides a new idea for the identification of the corrosion level of carbon steel in transmission towers.

The present study aimed to investigate the spatiotemporal dynamics of covert attention by simulating different degrees of central visual field defects in healthy subjects.An electroencephalogram (EEG) was recorded while 40 normal-sighted subjects performed a target discrimination task. Target stimuli simulated different defect degrees of the central visual field by artificially central scotomas (5, 10, 20, and 30 degrees of visual angle) masked on the center of black-and-white checkerboards. Event-related potentials (ERPs) and standardized low-resolution brain electromagnetic tomography (sLORETA) based on ERPs were analyzed.ERP results indicated that during early perceptual processes, compared with 5-degree and 10-degree defects, N1 amplitudes of 20-degree and 30-degree defects decreased, whereas P2 amplitudes significantly reduced in 30-degree defects. During later discrimination and decision processing, N2 amplitudes gradually increased from 5-degree to 30-degree defects, whereas P3 amplitudes gradually decreased. Source localization indicated that 5-degree and 10-degree defects had stronger activations than 20-degree and 30-degree defects from the occipital cortex to the ventral stream and dorsal streams. Especially, 30-degree defects primarily recruited additional activations in the ventrolateral prefrontal cortex and ventral stream and later caused the disconnection of dorsolateral prefrontal-posterior parietal cortices in the dorsal stream.Different degrees of central visual field defects differed in distinct spatiotemporal characteristics at multiple stages of covert attention, from top-down forward feedback and attentional allocation to executive controls through ventral and dorsal processing streams, suggesting that the combination of ERP and source localization can reveal the spatiotemporal control capacity of the cortex on central visual field defects.

Purpose Covert spatial attention directs the attentional spotlight to a particular part of the visual field and modulates the retinotopic organized oscillatory brain activity. This study aimed to investigate the electrophysiological characteristics of oscillatory brain activity when simulating different defect degrees of the central visual field. Methods The power of theta and alpha activity was extracted using time-frequency analysis in forty healthy participants enrolled in the three-stimulus oddball paradigm. Standard stimuli were black-and-white checkerboards. Target stimuli simulated different degrees of the central visual field defect by superimposing black discs with different radii (5, 10, 20, and 30 degrees of visual angle) on the center of the peripheral checkerboard stimulation, and distractor stimuli presented in the reverse form with a constant radius. Results By simulating central visual field defects, the increased theta power and decreased alpha power was observed when detecting target stimuli. Besides, the magnitude of increased theta power and decreased alpha power peaked at the 10-degree defect conditions, and gradually decayed to the 5 and 30-degree defect conditions, which separately indicated two key points in the visual field through the spatial attentional modulations. Conclusion Using cortical oscillatory dynamics in the time-frequency platform, the defect category of the central visual field could be quantified by alpha and theta oscillations in power differences. These findings suggest that cortical oscillations are sensitive markers for the discrimination of gradient effects of the central visual field defects and further demonstrate the phenomenon of functional dissociation in the visual field in covert spatial attention status.

Gas discharge theory as an important subject has been widely employed to solve various questions related to discharge. However, previous concerns about gas discharge were mainly related to some discharge situations in static gases, which do not consider the influence of airflow on discharge. In this paper, the influence of both the airflow direction that is parallel to the field direction and the airflow velocity on air discharge is studied. The airflow is found to induce an obvious polarity effect, which results in a substantial difference in the breakdown voltage values. Compared with the breakdown voltage in static air, the breakdown voltage in airflow decreases because of the downwind effect and increases because of the headwind effect. The relative mean free path of electrons, the diffusion radius of electrons, and the air density are the three major factors affecting the discharge process, and they change with the airflow direction and airflow velocity. The combined effects of those three factors determine the variation trends in breakdown voltage with airflow velocity. These results can provide guidance for the design and insulation coordination of high-voltage equipment in an airflow environment.

The diagrams of intergranular volume versus cementation volume brought up by Houseknecht (1987) and Ehrenberg (1989), are extensively used around the globe to assess the relative significance of compaction and cementation to porosity reduction in sandstones. However, Houseknecht (1987) overlooked the fact that the bulk sediment volume is dynamically compressed during burial, which directly leads to deviation in evaluating original porosity loss. The present discussion is based on the theoretical and contrastive analysis. These analyses indicate the compactional porosity loss calculated by Ehrenberg's (1989) method is always greater than Houseknecht's (1987) method with a maximum difference of 12.7%. In contrast, the cementation porosity loss using Ehrenberg's (1989) method is always less than Houseknecht's (1987). Besides, the demonstration based on the data of Wei et al. (2020) also supports Ehrenberg (1989). Therefore, the method proposed by Ehrenberg (1989) should be highly recommended to be granted as a reference far and wide.

To understand the flashover of roof insulators in high-speed airflows, the breakdown characteristics and mechanisms of a short needle–plate air gap are investigated. An interesting and important phenomenon is found based on an artificial wind tunnel: the breakdown voltage first increases and then decreases. An experiential formula is established to describe the relationship among the airflow velocity, gap distance, and breakdown voltage. A good consistency with the experimental results is obtained. Furthermore, the breakdown mechanisms of the air gap in high-speed airflows are proposed, and the phenomenon is explained and verified according to the theories of gas discharge and fluid dynamics. The airflow blowing effect, which includes the deflection effect and blown away effect, and the airflow density effect are proposed as two dominant factors that affect the breakdown process of the air gap in high-speed airflows. The variation trend of the breakdown voltage with the airflow velocity is predicted. Two extreme points are expected during the variation process; i.e., the breakdown voltage has a maximum and a minimum, to which more attention should be paid. This paper is helpful for the safety operation of roof insulators on the high-speed train.

With the launching of Lanzhou-Xinjiang high-speed railway in Northwest China, high-speed train running in sand environment will cause strong high-speed airflow with sand around it, which seriously threats the long-term service performance of roof insulators. To study the flashover characteristics of insulator under the condition, a small size wind tunnel system is established to simulate high-speed sand environment, the influence of airflow speed, sand particle size and sand flux on the flashover voltage of cylindrical insulator is investigated. Results show that, in pure high-speed airflow environment, the flashover voltage of insulator has an increase-decrease variation trend with the increase of airflow speed. The flashover mechanism is due to the combined effects of airflow blowing effect and airflow density. In sand environment, flashover voltage will decrease obviously which is caused by nonuniformity of electric field, but the decreasing degree will become small with the increase of airflow speed. Sand particle size and sand flux have negative influence on flashover voltage of insulator. These research results can provide theoretical basis for service performance of roof insulators in high-speed sand environment.

Purpose The dorsal attention network (DAN) and the ventral attention network (VAN) are known to support visual attention, but the influences of ocular dominance on the attention networks are unclear. We aimed to explore how visual cortical asymmetry of the attention networks correlate with neurophysiological oscillation and connectivity markers of attentional processes. Methods An oddball task with concentric circle stimuli of three different sizes (i.e., spot size of 5°, 20°, or 30° of visual angle) was used to vary task difficulty. Event-related oscillations and interareal communication were tested with an electroencephalogram-based visual evoked components as a function of ocular dominance in 30 healthy subjects. Results Accuracy rates were higher in the dominant eyes compared with the nondominant eyes. Compared with the nondominant eyes, the dominant eyes had higher theta, low-alpha, and low-beta powers and lower high-alpha powers within the nodes of VAN and DAN. Furthermore, visual information processed by the dominant and nondominant eye had different fates, that is, the dominant eyes mainly relied on theta and low-alpha connectivity within both the VAN and the DAN, whereas the nondominant eyes mainly relied on theta connectivity within the VAN and high-alpha connectivity within the DAN. The difference in accuracy rate between the two eyes was correlated with the low-alpha oscillations in the anterior DAN area and low-alpha connectivity of the left DAN. Conclusions The ocular dominance processing and interareal communication reveal a cortical asymmetry underlying attention, and this reflects a two-way modulatory mechanism within attention networks in the human brain.

According to the fluorescence characteristics of hydrocarbon inclusions under the microscope, the interpenetration relationship with the occurrence veins, and the homogenization temperature, the hydrocarbon inclusions developed in the Cambrian-Ordovician reservoir in Yingmian 7 area can be divided into four periods, which correspond to four hydrocarbon accumulation events respectively. The periods of accumulation determined by the analysis of homogenization temperature and burial history are as follows: late Caledonian to early Hercyian low mature heavy oil filling, late Hercyian medium mature normal oil filling, early Himalayan high mature light oil filling and late Himalayan over mature natural gas filling. Among them, periods of I, II hydrocarbon inclusions distribution range is limited, only visible in part of the wells in Yingmai 7 area; periods of III, IV hydrocarbon inclusions in Yingmai 7 area are widely distributed, which reveals the Himalayan period of the two-stage oil and gas filling on the reservoir formation.

To obtain the pollution agglomeration characteristics of insulators and its effect mechanism of Ultra High-Voltage DC transmission lines under natural sedimentary condition, a natural pollution accumulation system was set up and used to analyze the micro-shape features of the surface insulators on different conditions. The experimental results show that the surface pollution is respectively distributed as chain and granular shapes on the DC charged insulator and electrically neutral insulator, which indicates that the pollution agglomeration characteristics are influenced by the DC electric field significantly. Meanwhile, the radius of the pollution particles on the DC charged insulator is larger than that on the uncharged insulator. Based on the thermodynamics and electrostatics theory, this paper proposed the model of electric dipole between aerosol groups to explain the characteristics of the pollution distribution on the surface of the DC charged insulator and revealed the mechanism of aerosol particles radius affected by DC electric field. The conclusions of this paper can provide an experimental and theoretical basis for the UHV DC external insulation pollution characteristics and insulator flashover.

For HVAC and HVDC transmission lines which are partially in parallel in one corridor, coupling parameters between AC and DC transmission lines can be changed due to the length of extension sections which are not in parallel. And the generated electromagnetic coupling components at the two terminals of the DC line contain the effects of line parameters of extension sections. In this paper, the coupling components on the DC line, not all of which is in parallel with the AC line are studied in detail. The DC line is longer than the AC line and it may have extension sections on the both sides. Firstly, a new methodology is presented to calculate the coupling components of HVAC line upon HVDC line in the above situation. Then, the correctness and applicability of this method is illustrated and validated through a case study. Meanwhile, the key factors affecting the coupling between the AC and DC lines are analyzed. Finally, some suggestions have been proposed to provide as a construction reference which aims to optimize the electromagnetic coupling components on the DC line.

High-speed train running in sand environment will cause strong airflow mixed with sand, which seriously threats the long-term service performance of roof insulators. To study the flashover characteristics of insulator under the above condition, a small size wind tunnel system was established to simulate high-speed sand environment. The influences of several key factors, including airflow speed, sand particles size and sand flux on the flashover voltage of a cylindrical insulator, were investigated. Variation of flashover voltage with the airflow, whose speed covers the running velocity range of high-speed train, was obtained. A minimum flashover voltage was found. Mechanisms of the different factors influencing the flashover characteristics were clarified out, from the aspects of airflow density, trace of the charged particles and convection cooling effect. In the end, research on the effects of sand particles size and sand flux revealed a negative correlation with the flashover voltage. These research results will benefit the service performance of roof insulators in high-speed sand environment.

Hydrogen sulfide as the third endogenous gaseous mediator had protective effects against traumatic brain injury-induced neuronal damage in mice. However, the exact pathophysiological mechanism underlying traumatic brain injury is complicated and the protective role of H2S is not yet fully known. Therefore, we combined the mechanical injury (scratch) with secondary injury including metabolic impairment (no glucose) together to investigate the underlying cellular mechanism of hydrogen sulfide in vitro models of traumatic brain injury. In the present study, we found that H2S could prevent the scratch-induced decrease in the expression of cystathionine-β-synthetase, a key enzyme involved in the source of hydrogen sulfide, and endogenous hydrogen sulfide generation in PC12 cells. We also found that hydrogen sulfide could prevent scratch-induced cellular injury, alteration of mitochondrial membrane potential, intracellular accumulation of reactive oxygen species and cell death (autophagic cell death and apoptosis) in PC12 cells. It was also found that blocking PI3K/AKT pathway by LY294002, abolished the protection of H2S against scratch-induced cellular reactive oxygen species level and NRF2 accumulation and function in the nucleus. These results suggest that hydrogen sulfide protects against cell damage induced by scratch injury through modulation of the PI3K/Akt/Nrf2 pathway. This study raises the possibility that hydrogen sulfide may have therapeutic efficacy in traumatic brain injury.