Rough surface effect in terahertz near-field microscopy: 3D simulation analysis.

Terahertz scattering-type scanning near-field optical microscopy (THz-s-SNOM) has emerged as a powerful technique for high-resolution imaging. However, most previous studies have focused on simplified smooth surface models, overlooking the realistic surface roughness induced by contamination during sample preparation. In this work, we present a novel 3D model, to the best of our knowledge, that combines the point dipole model with the finite element method to investigate the influence of sample morphology on scattered signals. We explore surfaces with a protrusion, a depression, and random roughness, characterizing the variations in scattered signals and highlighting the role of higher-order scattering in mitigating surface roughness effects. Our findings provide valuable insights into the impact of sample morphology on THz-s-SNOM imaging.

A High-Power 170 GHz in-Phase Power-Combing Frequency Doubler Based on Schottky Diodes.

In this paper, a high-power 170 GHz frequency doubler based on a Schottky diode is proposed using an in-phase power-combining structure. Unlike a conventional power-combining frequency doubler, the proposed frequency doubler utilizes the combination of a T-junction power divider and two bend waveguides to eliminate the phase difference between the two output ports of the T-junction power divider, so as to achieve in-phase power combining with a concise structure. The frequency doubler was fabricated on a 50 µm thick AlN high-thermal-conductivity substrate to reduce the impact of the thermal effect on the performance. The measured results show that the doubler exhibits a conversion efficiency of 11-31.3% in the 165-180 GHz band under 350-400 mW of input power, and a 118 mW peak output power with a 31.3% efficiency was measured at 174 GHz `when the input power was 376 mW. A good agreement was achieved between the simulation results and the measured performance of the doubler, which proves the effectiveness of the proposed in-phase power-combining structure.

Determination of the Accuracy of the Straight Bevel Gear Profiles by a Novel Optical Coaxial Multi-Ring Measurement Method.

Straight bevel gears are widely used in mining equipment, ships, heavy industrial equipment, and other fields due to their high capacity and robust transmission. Accurate measurements are essential in order to determine the quality of bevel gears. We propose a method for measuring the accuracy of the top surface profile of the straight bevel gear teeth based on binocular visual technology, computer graphics, error theory, and statistical calculations. In our method, multiple measurement circles are established at equal intervals from the small end of the top surface of the gear tooth to the large end, and the coordinates of the intersection points of these circles with the tooth top edge lines of the gear teeth are extracted. The coordinates of these intersections are fitted to the top surface of the tooth based on NURBS surface theory. The surface profile error between the fitted top surface of the tooth and the designed surface is measured and determined based on the product use requirements, and if this is less than a given threshold, the product is acceptable. With a module of 5 and an eight-level precision, such as the straight bevel gear, the minimum surface profile error measured was -0.0026 mm. These results demonstrate that our method can be used to measure surface profile errors in the straight bevel gears, which will broaden the field of in-depth measurements for the straight bevel gears.

Accurate Characterization of the Adhesive Layer Thickness of Ceramic Bonding Structures Using Terahertz Time-Domain Spectroscopy.

Ceramic adhesive structures have been increasingly used in aerospace applications. However, the peaks of the signal on the upper and lower surface of the adhesive layer are difficult to measure directly due to the thin thickness of the adhesive layer and the effect of the attenuation dispersion of the ceramic layer. Thus, the existing non-destructive testing techniques have been ineffective in detecting adhesive quality. In this paper, the thickness of the adhesive layer is measured using terahertz time-domain spectroscopy. A sparse deconvolution method is proposed for the terahertz time-domain spectral signal of ceramic adhesive structures with different adhesive layer thicknesses. The results show that the methods proposed in this paper can realize the separation of reflection signals for glue layers with a thickness of 0.20 mm. By comparing with a wavelet denoising method and a modified covariance method (AR/MCM), the effectiveness of the sparse deconvolution method in estimating the thickness of the glue layer is demonstrated. This work will provide the theoretical and experimental basis for using terahertz time-domain spectroscopy to detect the homogeneity of ceramic adhesive structures.

120 GHz Frequency-Doubler Module Based on GaN Schottky Barrier Diode.

Traditional GaAs-based frequency multipliers still exhibit great challenges to meet the demand for solid-state high-power THz sources due to low breakdown voltage and heat dissipation of the Schottky barrier diode (SBD). In this study, a GaN SBD chain was fabricated with n-/n+-GaN structure. As a consequence, the breakdown voltage of 54.9 V at 1 µA and cut-off frequency of 587.5 GHz at zero bias were obtained. A 120 GHz frequency-doubler module based on the GaN SBD chain was designed and fabricated. When driven with 500 mW input power in a continuous wave, the output power of the frequency-doubler module was 15.1 mW at 120 GHz. Moreover, the experiments show that the frequency-doubler module can endure an input power of 2 W. In addition, it is worth noting that the SBD chain works well at an anode temperature of 337.2 °C.

Prediction and analysis of natural gas consumption in chongqing with a grey prediction model group in the context of COVID-19.

In this paper, a grey prediction model group is employed to quantitatively study the impact of COVID-19 on natural gas consumption in Chongqing, China. First, a grey prediction model group suitable for the prediction of Chongqing's natural gas consumption is introduced, which consists of GM(1,1), TWGM(1,1), and the newly-developed ODGM(1,1). Then, the model group is constructed to predict Chongqing's natural gas consumption in 2020. Finally, compare the predicted results of the model group with the actual consumption and quantitatively analyze the impact of the epidemic on natural gas in Chongqing. It is found that the impact of the epidemic on the consumption of natural gas in the first quarter of the year is very small, but relatively bigger in the second and third quarters. The study is of positive significance to maintain the supply and demand balance of natural gas consumption in Chongqing in the background of COVID-19; and it enriches and develops the theoretical system of grey prediction models.

Super-resolution reconstruction of terahertz images based on a deep-learning network with a residual channel attention mechanism.

To date, the existing terahertz super-resolution reconstruction methods based on deep-learning networks have achieved noteworthy success. However, the terahertz image degradation process needs to fully consider the blur and noise of the high-frequency part of the image during the network training process, and cannot be replaced simply by interpolation, which has high complexity. The terahertz degradation model is systematically investigated, and effectively solves the above problems by introducing the remaining channel mechanism into the deep-learning network. On the one hand, an image degradation model suitable for the terahertz imaging process is adopted for the images in the training dataset, which improves the accuracy of network training. On the other hand, the residual channel attention mechanism is introduced to realize the adaptive adjustment of the dependence between network channels, which results in the network being more focused on the restoration of high-frequency information, thereby supporting the extraction of high-frequency edge details in the image. In addition, experimental results demonstrate that this method successfully improves the peak signal-to-noise ratios, and offers clearer edge details and a better overall reconstruction effect. We believe that this work may provide a new possibility to improve the resolution of terahertz images.

Using Multi-Scale Convolutional Neural Network Based on Multi-Instance Learning to Predict the Efficacy of Neoadjuvant Chemoradiotherapy for Rectal Cancer.

BACKGROUND: At present, radical total mesorectal excision after neoadjuvant chemoradiotherapy is crucial for locally advanced rectal cancer. Therefore, the use of histopathological images analysis technology to predict the efficacy of neoadjuvant chemoradiotherapy for rectal cancer is of great significance for the subsequent treatment of patients. METHODS: In this study, we propose a new pathological images analysis method based on multi-instance learning to predict the efficacy of neoadjuvant chemoradiotherapy for rectal cancer. Specifically, we proposed a gated attention normalization mechanism based on the multilayer perceptron, which accelerates the convergence of stochastic gradient descent optimization and can speed up the training process. We also proposed a bilinear attention multi-scale feature fusion mechanism, which organically fuses the global features of the larger receptive fields and the detailed features of the smaller receptive fields and alleviates the problem of pathological images context information loss caused by block sampling. At the same time, we also designed a weighted loss function to alleviate the problem of imbalance between cancerous instances and normal instances. RESULTS: We evaluated our method on a locally advanced rectal cancer dataset containing 150 whole slide images. In addition, to verify our method's generalization performance, we also tested on two publicly available datasets, Camelyon16 and MSKCC. The results show that the AUC values of our method on the Camelyon16 and MSKCC datasets reach 0.9337 and 0.9091, respectively. CONCLUSION: Our method has outstanding performance and advantages in predicting the efficacy of neoadjuvant chemoradiotherapy for rectal cancer. Clinical and Translational Impact Statement -This study aims to predict the efficacy of neoadjuvant chemoradiotherapy for rectal cancer to assist clinicians quickly diagnose and formulate personalized treatment plans for patients.

The Development of Frequency Tripler Based on Six-Anode Schottky Varactors.

The development of a millimeter-wave unbalanced frequency tripler based on the nonlinear characteristics of planar Schottky varactors is presented. The entire module is designed by hybrid integration. A frequency multiplier circuit model was established to reflect the influence of diode parameters and the impedance matching on the multiplier in different frequency bands. The effect of junction imbalance on the output power of the frequency multiplier was investigated and the multiplier was improved based on the basic design. The addition of a cut microstrip stub in the improved diode unit reduced the impact of a power imbalance on frequency multiplier performance. The characteristics of the multiplier circuit were analyzed by the full-wave electromagnetic simulation of the three-dimensional structure and the harmonic balance simulation of the circuit. Test results showed that the peak output power of the improved frequency tripler was 12.6 mW at 277 GHz with an input power of 200 mW, an effective 12% improvement over the basic design.

The relation between self-stigma and loneliness in visually impaired college students: Self-acceptance as mediator.

BACKGROUND: Loneliness, a negative emotion that is common in college students, may cause psychological disorders and behavioral issues. Particularly vulnerable are visually impaired college students, who are at an increased risk of loneliness. OBJECTIVES: This study was aimed at explaining the current situation of loneliness among visually impaired college students as well as its influencing factors and exploring the intermediary role of self-acceptance between self-stigma and loneliness. METHOD: Seventy-eight college students with visual impairment completed a series of self-report questionnaires, including the Self-Stigma of Disabled Scale (SSDS), the Self-Acceptance Questionnaire (SAQ), and the University of California-Los Angeles (UCLA) Loneliness Scale. Mediation analyses were conducted using PROCESS in SPSS. RESULTS: Participants' mean loneliness score was 44.97 ± 9.35. Two survey factors were significantly associated with loneliness: visual impairment status and relationship with parents (p < 0.05). When controlling for extent of visual damage and relationship with parents, self-stigma showed a significant predictive effect on loneliness (B = 0.37, t = 4.1023, p < 0.01). CONCLUSIONS: In China, visually impaired students suffer from a high level of loneliness, and self-acceptance plays a central role in connecting their self-stigma and loneliness.

The Design of Terahertz Frequency Quadruplers Based on Discrete Schottky Diodes.

On the basis of the W-band power source, a single-stage frequency quadrupler method was used to implement two 335 GHz frequency quadruplers. The two frequency quadruplers adopted a traditional binomial matching structure and an improved gradient line matching structure, respectively. An idle loop was added to the overall circuit in the design of the DC filter and low-pass filter. The improved gradient line matching structure reduced the circuit length while increasing the bandwidth, effectively reducing the power loss on the transmission line. A micro-strip circuit was fabricated with a 50 µm thick quartz circuit and was mounted onto a split waveguide block. The results showed that the output power of the quadrupler with the improved matching structure was better than that of the quadrupler with the conventional matching structure. The peak output power of the improved frequency quadrupler was 4.75 mW at 333 GHz when driven with 200 mW. In contrast, this improved structure broadened the bandwidth by 8 GHz and reduced the length of the substrate by 0.607 mm, effectively reducing the length of the traditionally designed circuit by 11.5%.

Nestin is significantly associated with the overall survival of nonsmall cell lung cancer: A meta-analysis.

AIMS: Some studies investigated the association between nestin and the overall survival (OS) of nonsmall cell lung cancer (NSCLC). However, the results were conflicted and inconclusive. Therefore, we performed this meta-analysis to determine the association between nestin and OS of NSCLC. MATERIALS AND METHODS: PubMed and EMBASE were searched to find relevant studies. The strength of the association was calculated with the hazard ratios (HRs) and respective 95% confidence intervals (CIs). RESULTS: High expression of nestin was significantly associated with OS of NSCLC (HR = 2.09; 95% CI = 1.59-2.77). In the stratified analysis by race, we found that the expression of nestin was significantly associated with OS of NSCLC in Asians (HR = 3.02; 95% CI = 1.80-5.07) and Caucasians (HR = 1.81; 95% CI = 1.21-2.71). In addition, when we limited the meta-analysis to studies that controlled for clinical parameters, a significant association between nestin and OS of NSCLC remained (HR = 2.19; 95% CI = 1.54-3.11). A sensitivity analysis showed no substantial modification of the estimates after exclusion of individual studies. CONCLUSIONS: In conclusion, this meta-analysis suggested that high expression of nestin was significantly associated with OS of NSCLC.

The Design of Terahertz Monolithic Integrated Frequency Multipliers Based on Gallium Arsenide Material.

A global design method for a terahertz monolithic integrated frequency multiplier is proposed. Compared with a traditional independent design, the method in this paper adopts overall optimization and combines the device with the circuit design. The advantage is that it provides a customized design for frequency multipliers according to specifications. On the basis of the gallium arsenide process of the Institute of Microelectronics, Chinese Academy of Sciences, two types of Schottky diodes have been developed to meet the needs of different designs. On the one hand, a Schottky diode with a 3 µm junction's diameter was used in the design of the 200 GHz balanced doubler and, on the other hand, a diode with a 5 µm diameter was used in the 215 GHz unbalanced tripler. The measured results indicated that the output power of the doubler was more than 250 µW at 180~218 GHz, and the maximum was 950 µW at 198 GHz when driven with 12.3 mW, whereas that of the tripler was above 5 mW at 210~218 GHz and the maximum exceeded 10 mW. Such frequency multiplier sources could be widely used in terahertz imaging, radiometers, and so on.

An improved gray prediction model for China's beef consumption forecasting.

To balance the supply and demand in China's beef market, beef consumption must be scientifically and effectively forecasted. Beef consumption is affected by many factors and is characterized by gray uncertainty. Therefore, gray theory can be used to forecast the beef consumption, In this paper, the structural defects and unreasonable parameter design of the traditional gray model are analyzed. Then, a new gray model termed, EGM(1,1,r), is built, and the modeling conditions and error checking methods of EGM(1,1,r) are studied. Then, EGM(1,1,r) is used to simulate and forecast China's beef consumption. The results show that both the simulation and prediction precisions of the new model are better than those of other gray models. Finally, the new model is used to forecast China's beef consumption for the period from 2019-2025. The findings will serve as an important reference for the Chinese government in formulating policies to ensure the balance between the supply and demand for Chinese beef.

Strain and mechanical properties of the VCM multilayer sheet and their composites using the digital speckle correlation method.

The digital speckle correlation method (DSCM) is introduced to solve the challenging problems in the related geometric measurement. Theoretical calculations of strain are deduced using the DSCM. Corresponding strains along x and y directions are obtained from uniaxial tension experiments and digital speckle measurements, using the VCM nondeep drawing multilayer sheet, the VCM deep-drawing multilayer sheet, clad films, nondeep drawing substrate, and deep-drawing substrate sheet as the targeted experimental objects. The results show that the maximum strains along the x direction of the VCM nondeep drawing multilayer sheet, the VCM deep-drawing multilayer sheet, clad film, nondeep drawing substrate, and deep-drawing substrate sheet are 68.473%, 48.632%, 91.632%, 50.784% and 40.068%, respectively, while the maximum strains along the y direction are -2.657%, -15.381%, 2.826%, -9.780% and -7.783%, respectively. The mechanical properties of the VCM multilayer sheet are between those of the substrate and clad film, while mechanical properties of the VCM deep-drawing multilayer sheet are superior to those of the VCM nondeep drawing multi-layer sheet.

Peneciraistin C induces caspase-independent autophagic cell death through mitochondrial-derived reactive oxygen species production in lung cancer cells.

Peneciraistin C (Pe-C) is a novel spiroketal compound isolated from the saline soil derived fungus Penicillium raistrickii. Our previous study showed that Pe-C exerted a potent cytotoxic effect on many kinds of cancer cell lines, especially on human lung cancer A549 cells. Here, we report the anticancer mechanisms of Pe-C in a variety of lung cancer cells. The results showed that Pe-C induced caspase-independent autophagic cell death and elevated mitochondrial-derived reactive oxygen species levels. Interestingly, if autophagy was blocked by 3-methyladenine or Atg5 siRNA, Pe-C triggered a shift from autophagic cell death into caspase-dependent apoptotic cell death. In addition, cotreatment with the antioxidant N-acetyl-(L)-cysteine or Mito-TEMPO could effectively reverse the effect of the enhanced reactive oxygen species production, which in turn almost completely prevented the cell death induced by Pe-C. Thus, this study provided new insights into the mechanisms underlying Pe-C-mediated cell death, which indicated that Pe-C could be a potential drug candidate for therapy of lung cancers.

Characterization of H5N1 influenza viruses isolated from migratory birds in Qinghai province of China in 2006.

Avian influenza H5N1 viruses pose a significant threat to human health because of their ability to infect humans directly. In the paper, three highly pathogenic H5N1 influenza viruses were isolated from three species of migratory birds in Qinghai Province of China in 2006. The analysis of the genome sequences indicated that the three isolates shared high homology with each other (94% to 99%). Three isolates shared a common ancestor and were closest to strains isolated from Qinghai and Siberia in 2005, but distinct from poultry viruses found in Southeast Asia. In experimental infection, all three viruses were highly pathogenic to chickens and mice. The results suggest that highly pathogenic avian influenza H5N1 viruses still exist in the migratory birds and could spread to other regions with wild bird migration.

[Multiple organ dysfunction scoring system: comparison and evaluation of correlation and accuracy of the three scoring systems in predicting the outcome of multiple organ dysfunction syndrome on highland].

OBJECTIVE: To study the characteristics of the diagnostic parameters of acute respiratory distress syndrome/multiple organ dysfunction syndrome on plateau (H-ARDS/MODS) and compare the accuracy of the three MODS scoring criteria in predicting the outcome of syndrome. METHODS: Five hundred and forty cases fulfilling the criteria of MODS were divided into four groups according to the altitude of their inhabitation area: control group (on plain, CG, n=113, altitude: <430 m), moderate high altitude group 1 (H1G, n=314, altitude: 1,517 m), moderate high altitude group 2 (H2G, n=78, altitude: 2,261 m to 2,400 m) and high altitude group (HG, n=35, altitude: 2 808 m to 3 400 m). According to the diagnostic criteria of Lushan conference and Marshall (1995) commonly used on plain, and Lanzhou criteria drafted by the authors, three data analyzing models were set up to draw the receiver operating characteristic (ROC) curves, the Yordon Index and the optimum cutoff points of the parameters were calculated and the accuracy of the three respective diagnostic criteria was evaluated in predicting the outcome of ARDS/MODS. Multiple factors affecting the outcome of MODS were analyzed using the method of stepwise forward regress model. RESULTS: Following the increase in altitude, Lanzhou criteria was clearly superior to the other two criteria in the area of ROC, the sensitivity, the specificity, and also for the optimum cutoff points of MODS. Multi-variable regression analysis showed that the impacting factor of Lanzhou criteria was the highest (P<0.05). CONCLUSION: (1)Some parameters of the current diagnostic criteria of ARDS/MODS are not suitable in moderately high or high altitude areas. It is necessary to set up the diagnostic criteria of H-ARDS/MODS. (2)Some clinical characteristics might change in areas 1,500 m altitude or higher. The pathophysiological mechanism might be attributable to peculiar biologic reactions due to hypoxia stress reaction, and it is worth further study.

[Criteria suitable for diagnosis of acute respiratory distress syndrome/multiple organ dysfunction syndrome at moderately high altitude area].

OBJECTIVE: To compare the diagnostic parameters of acute respiratory distress syndrome/multiple organ dysfunction syndrome (ARDS/MODS) at high altitude (H-ARDS/MODS) with that on plain, and to establish a more practical diagnostic criterion of H-ARDS/MODS. METHODS: Five hundred and five cases fulfilled the criteria for the diagnosis of ARDS/MODS were divided into three groups according to the altitude of their habitation: control group including inhabitants (<430 m) on plain (CG, n=113), moderate high altitude group 1 inhabitants at the altitude of 1,517 m (H1G, n=314), moderate high altitude group 2 inhabitants at the altitude of 2,261 m to 2,400 m (H2G, n=78). The ARDS/MODS scores of the three groups were made according to the diagnostic criteria of Lushan conference, Marshall(1995) and Lanzhou criteria drafted by the authors respectively to set up three data analyzing models, followed by plotting of receiver operating characteristic curves (ROC curve) and calculation of the Yordon Index and the optimum cutoff points of the parameters,in order to study the accuracy of the three diagnostic criteria in predicting the outcome of the patients suffering from ARDS/MODS. RESULTS: In CG group, the differences were not significant in area of ROC, the maximal Yordon Index, the optimum cutoff points and the sensitivity and the specificity for three criteria; but the differences were significant for the three criteria in H1G group. Further investigation in comparing the ROC values of lung, brain, heart and kidney, the Lanzhou criteria were more advantageous in the high altitude than the other criteria. CONCLUSION: (1)The current diagnostic criteria of ARDS/MODS are not suitable for the diagnosis of these syndromes in moderately high or high altitude areas. It is necessary to revise the diagnostic criteria of H-ARDS/MODS. (2)One thousand five hundred and seventeen meters in altitude might be considered to be an important borderline, above with the diagnostic criteria of ARDS/MODS for patients inhabiting on plain could not be suitably applied to those living above this level.

[Study of diagnostic criteria of acute respiratory distress syndrome and multiple organ dysfunction syndrome at high altitude: revised draft of the diagnostic criteria of high acute respiratory distress syndrome drawn in Lanzhou conference].

OBJECTIVE: To compare the difference of the diagnostic parameters of acute respiratory distress syndrome/multiple organ dysfunction syndrome (ARDS/MODS) at high altitude (H-ARDS/MODS) with that on plains and reevaluate the practicality and feasibility of the diagnostic criteria of H-ARDS (Lanzhou conference, 1999). METHODS: Three hundred and sixty cases with relatively complete data were divided into three groups according to their originating altitude: control group on plains (CG, n=93), high altitude group 1 at the altitude of 1,517 m (H1G, n=223), high altitude group 2 at the altitude of 2,261-2,400 m (H2G, n=44). The ARDS/MODS scorings of the three groups were carried out according to the diagnostic criteria of Lushan Conference, Marshall (1995) and Lanzhou criteria drafted by the authors and the receiver operating characteristic curves (ROC curve) were made to predict the outcome of MODS. RESULTS: In CG group, the area of ROC, the susceptibility and specificity were 0.823, 0.833, 0.731, respectively according to Lushan criteria, which were better than those (0.815, 0.767, 0.763) according to Marshall criteria. Then in group H2G, the area of ROC, the susceptibility and specificity according to Lushan criteria were lower than those according to Marshall criteria: 0.855, 0.583, 0.969 vs 0.914, 1.000, 0.657. The optimum cutoff points of partial pressure of oxygen in artery (PaO(2))/fractional concentration of inspired oxygen (FiO(2)) were 198.32 mmHg, 131.50 mmHg and 97.58 mmHg in group CG, H1G and H2G. CONCLUSION: (1) There are significant differences between the diagnostic criteria of ARDS at high altitude and that on plains. The altitude of 1 517 m would be an important border line in diagnosing H-ARDS. (2) The drafted diagnostic criteria of ARDS at high altitude are feasible and practical in this region, but the range of the parameters is still wide, which need to be properly amended. (3) The changing tendency of the parameters of MODS at high altitude is different from that on plains, but the amount of sample needs to be accumulated further and the Lanzhou criteria needs to be perfected.