Effect of surface retaining elements on rock stability:laboratory investigation with sand powder 3D printing

This study aims to investigate the benefcial efects of surface retaining elements (SREs) on the mechanical behaviors of bolted rock and roadway stability. 3D printing (3DP) technology is utilized to create rock analogue prismatic specimens for conducting this investigation. Uniaxial compression tests with acoustic emission (AE) and digital image correlation techniques have been conducted on 3DP specimens bolted with diferent SREs. The results demonstrate that the strength and modulus of elasticity of the bolted specimens show a positive correlation with the area of the SRE;the AE characteristics of the bolted specimens are higher than those of the unbolted specimen, but they decrease with an increase in SRE area, thus further improving the integrity of the bolted specimens. The reinforcement efect of SREs on the surrounding rock of roadways is further analyzed using numerical modelling and feld test. The results provide a better understanding of the role of SREs in rock bolting and the optimization of rock bolting design. Furthermore, they verify the feasibility of 3DP for rock analogues in rock mechanics tests.

土地财政影响经济增长的作用机理及空间效应研究

本文旨在研究土地财政影响经济增长的作用机理以及空间效应,为促进经济可持续高质量发展和转变地方土地财政逐底竞争提供决策参考。论文在理论分析提出2个研究假说的基础上,基于1999—2016年全国31个省级(未包含中国港澳台地区数据)层面的面板数据,应用空间杜宾模型(SDM)进行了实证分析。研究发现:①土地财政对经济增长的影响呈"倒U形"趋势,说明土地出让具有的收入改善效应和土地融资具有的政府债务延缓效应只在短期内对经济增长具有正向促进作用,但长期来看,土地资源稀缺性导致的土地财政不可持续,会对经济增长产生负向影响。②土地财政对经济增长存在显著的负向空间影响,即地方政府间的土地财政竞争存在逐底效应,对地区经济增长产生不利影响。

Increased expression of DLX2 correlates with advanced stage of gastric adenocarcinoma

AIM:To investigate the expression of distal-less homeobox 2 (DLX2) in gastric adenocarcinoma and its clinicopathological significance. METHODS:Gastric adenocarcinoma tissues were obtained from gastrectomy specimens of 129 patients from the Department of Surgery and Pathology, the Second Affiliated Hospital of Kunming Medical University. Sixty cases of normal gastric tissues were collected from gastrectomy specimens of adjacent gastric cancer margins greater than 5 cm. Patient diagnosis was established pathologically, and no patient had received chemotherapy or radiotherapy before surgery. All tissue specimens were formalin-fixed and paraffin-embedded. Immunohistochemistry was carried out to investigate the expression of DLX2 in 129 gastric adenocarcinoma tissues and 60 adjacent normal tissues. The immunos-taining reaction was semiquantitatively evaluated based on the proportion of positive cells and the median staining intensity in normal gastric epithelial cells or tumor cells. All patients had follow-up records for more than 5 years. Correlations of DLX2 expression with clinicopathological features and prognosis of patients with gastric adenocarcinoma were analyzed. All statistical analyses were performed using the SPSS 17.0 software. RESULTS:The positive expression of DLX2 was detected in 68 (52.7%) cases of 129 gastric adenocarcinoma tissues and 14 (23.3%) cases of 60 adjacent normal tissues. The difference in DLX2 expression between gastric adenocarcinoma tissues and adjacent normal tissues was statistically significant (Ⅹ2 = 14.391, P < 0.001). Moreover, high expression of DLX2 was detected in 48 (37.2%) cases of 129 human gastric cancer tissues, but not in adjacent normal tissues. The expression of DLX2 correlated with the size of tumor (P = 0.001), depth of invasion (P = 0.008), lymph node metastasis (P = 0.023) and tumor-node-metastasis stages (P = 0.020), but was not correlated with age, gender, histological differentiation and distant metastasis. The Kaplan-Meier survival analysis revealed that survival time of patients with high DLX2 expression was significantly shorter than that with low DLX2 expression. However, the multivariate analysis showed that invasion depth (P < 0.001), lymph nodes metastasis (P = 0.001) and distant metastasis (P < 0.001) were independent prognostic factors for patients with gastric adenocarcinoma, but DLX2 expression, tumor location and tumor size were not. CONCLUSION:These results suggest that increased expression of DLX2 may correlate with the advanced stage of gastric adenocarcinoma, and it may contribute to tumor development.

Specific Emitter Identification for IoT Devices Based on Deep Residual Shrinkage Networks

Specific emitter identification can distin-guish individual transmitters by analyzing received signals and extracting inherent features of hard-ware circuits.Feature extraction is a key part of traditional machine learning-based methods,but manual extrac-tion is generally limited by prior professional knowl-edge.At the same time,it has been noted that the per-formance of most specific emitter identification meth-ods degrades in the low signal-to-noise ratio(SNR)environments.The deep residual shrinkage network(DRSN)is proposed for specific emitter identification,particularly in the low SNRs.The soft threshold can preserve more key features for the improvement of performance,and an identity shortcut can speed up the training process.We collect signals via the receiver to create a dataset in the actual environments.The DRSN is trained to automatically extract features and imple-ment the classification of transmitters.Experimental results show that DRSN obtains the best accuracy un-der different SNRs and has less running time,which demonstrates the effectiveness of DRSN in identify-ing specific emitters.

A novel method for chemistry tabulation of strained premixed/stratified flames based on principal component analysis

The principal component analysis （PCA） is used to analyze the high dimen- sional chemistry data of laminar premixed/stratified flames under strain effects. The first few principal components （PCs） with larger contribution ratios axe chosen as the tabu- lated scalars to build the look-up chemistry table. Prior tests show that strained premixed flame structure can be well reconstructed. To highlight the physical meanings of the tabu- lated scalars in stratified flames, a modified PCA method is developed, where the mixture fraction is used to replace one of the PCs with the highest correlation coefficient. The other two tabulated scalars are then modified with the Schmidt orthogonalization. The modified tabulated scalars not only have clear physical meanings, but also contain passive scalars. The PCA method has good commonality, and can be extended for building the thermo-chemistry table including strain rate effects when different fuels are used.

Construction and Application of High Temperature Heat Damage Index for River Crab Culture in Hongze Lake Beach

Agrometeorology and agricultural statistics methods were used to analyze the cases of high temperature heat damage to crab breeding since 2008 in Hongze Lake Beach, finding that the high temperature heat damage was mainly under the comprehensive effects of the highest temperature, duration of high temperature weather, amount of precipitation and sunshine hours. Based on the function relation between the high temperature heat damage index and the influence factors, the linear model was used to describe the weight coefficient of each heat damage factor by using the synthesis correlation of multiple factors. The historical values of the influencing factors were used to make statistical calculation of the heat damage index model of crab culture in Hongze Lake Beach, which achieved good effects when applied in the meteorological operation of river crab culture.

Site testing campaign for the Large Optical Telescope at the Ali site

The Large Optical/infrared Telescope(LOT)is a ground-based 12 m diameter telescope which is proposed to be built in western China.The site selection for LOT in China began in 2016,and Ali was listed as one of the three candidate sites.Remote studies and local surveys have been carried out for more than 15 years in western China,and the results show that Ali is a promising site with comprehensive quality in terms of atmospheric and supporting conditions.An overview of the site testing campaign at the Ali site from 2016 to 2019 is presented.After the two years of data collection,the overall median seeing value is found to be 1.17 arcsec,the observable nights are 81.71%and the good observable nights are 71.76%.The weather conditions as follows,the median night temperature value is-5.18℃,the median night relative humidity value is 41.25%,the median night atmospheric pressure value is 540.92 hPa,the median night wind speed value is 7.41 m s-1 and the mainly wind direction is southwestern(SW).The median night sky background value is 22.07 magV.We also discuss the wind speed at different locations on-site,the possibility of light pollution and the effect of wind speed on differential image motion monitor(DIMM)seeing measurements.

改良连续单直针缝合法治疗早期外伤性睫状体脱离的疗效

目的:观察改良的连续单直针缝合法治疗早期外伤性睫状体脱离的临床效果。方法:对我院于2017-07/2018-05收治的外伤所致睫状体脱离伴黄斑水肿患者25例的临床资料进行回顾性分析,术前采用超声生物显微镜(UBM)确定睫状体脱离的部位和范围,应用光学相干断层扫描技术(OCT)观察黄斑水肿情况。在眼球密闭状态下使用改良连续单直针缝合法进行缝合修复,同时滴用扩瞳剂和皮质类固醇类药物控制炎症。术后检测眼压、视力,UBM观察睫状体复位情况,OCT观察黄斑水肿恢复情况。结果:患者术后睫状体脱离基本复位。20眼眼压提高到9~21mmHg,3眼仍低于5mmHg。23眼矫正视力均有提高,2眼视力不提高。黄斑水肿减轻或消退。结论:改良连续单直针缝合法是在玻璃体腔及前房密闭的情况下连续单直针缝合睫状体,是一种微创、安全、有效的手术方式。

Neoadjuvant chemoradiotherapy for resectable esophageal cancer:an in-depth study of randomized controlled trials and literature review

Surgery following neoadjuvant chemoradiotherapy(NCRT) is a common multidisciplinary treatment for resectable esophageal cancer(EC). After analyzing 12 randomized controlled trials(RCTs), we discuss the key issues of surgery in the management of resectable EC. Along with chemoradiotherapy, NCRT is recommended for patients with squamous cell carcinoma(SCC) and adenocarcinoma(AC), and most chemotherapy regimens are based on cisplatin, fluorouracil(FU), or both(CF). However, taxane-based schedules or additional studies, together with newer chemotherapies, are warranted. In nine clinical trials, post-operative complications were similar without significant differences between two treatment groups. In-hospital mortality was significantly different in only 1 out of 10 trials. Half of the randomized trials that compare NCRT with surgery in EC demonstrate an increase in overall survival or disease-free survival. NCRT offers a great opportunity for margin negative resection, decreased disease stage, and improved loco-regional control. However, NCRT does not affect the quality of life when combined with esophagectomy. Future trials should focus on the identification of optimum regimens and selection of patients who are most likely to benefit from specific treatment options.

Silk Fibroin Scaffolds Direct Neural and Glial Differentiation from Embryonic Stem Cells

Spinal cord injury repair is one of the major challenges in medicine,as it can lead to permanent loss of function of central nervous system and damage to other function of the body.Stem cell transplantation together with tissue engineering is increasingly becoming a potential choice of treatment.However,direct transplantation of stem cells without scaffolds has yielded poor clinical outcome.Here we show a strategy of using mouse embryonic stem cells(ESCs)cultured within a silk fibroin(SF)based,three-dimensional scaffold with oriented channels by a directional temperature field freezing technique and lysophilization.We find that the ESCs maintained proliferation and migrated in the scaffolds and the cells migrated fastest along the SF channels.SF scaffolds contributed to ESC differentiation into neural and glial cell like cells and expressions of the neural and glial cell markers MAP2 and GFAP were greatly elevated when retinoic acid was used as an inducing factor.Our results suggest that this approach may offer some hope in the future for spinal cord injury repair using SF scaffolds and ESCs.

Differentiation of Mouse Fibroblasts into Valvular Endothelial Cell Like Cells

The technology of induced pluripotent stem cell(iPSCs)has enabled the conversion of somatic cells into primitive undifferentiated cells via reprogramming.This approach provides possibilities for cell replacement therapies and drug screening,but the potential risk of tumorigenesis hampers further development and application.How to generate required differentia-ted cells without initiating tumor progression remains a huge challenge.Here we show that mouse embryonic fibroblasts could be differentiated into valvular endothelial cell(VEC)like cells.VECs are critical in valve replacements in aortic valve failure.VEC-associated gene and protein expression and functional assays were quantified for these VEC-like cells.We show that mouse embryonic fibroblasts could be converted into VEC-like cells.Our results suggest that it is possible to convert mouse embryonic fibroblasts into VEC-like cells without first reprogramming them into pluripotent stem cells,minimizing the possibility of tumorigenesis.

海上风电增速箱斜齿轮副接触仿真网格控制策略

文章首先研究了多组“两弹性圆柱法向接触”算例的网格无关性验证过程,总结得到了通过接触压力、接触带半宽网格无关性验证时的接触区网格尺寸阈值为1/4倍接触带半宽的一般性结论,并将该结论引申到斜齿轮接触问题中。研究表明:基于该结论进行接触区网格划分,可以在不进行网格无关性验证的前提下求解得到合理的斜齿轮接触压力及接触带半宽结果,从而大幅提高仿真效率。

56例同时性多原发食管鳞癌淋巴结转移因素分析

目的:探讨同时性多原发食管鳞癌(synchronous multiple primary esophageal squamous cell carcinoma,SMESC)淋巴结转移的特点及预后因素。方法:收集2011年1月至2018年12月收治的56例SMESC患者的临床病例资料,回顾分析各部位的淋巴结转移率,研究不同癌灶浸润深度、长度等因素对淋巴结转移的影响。结果:56例SMESC患者中34例有淋巴结转移,淋巴结转移率为60.7%,颈部、上、下纵隔和腹部的淋巴结转移率分别为16.7%、34.7%、32.7%和38.2%。不同癌灶部位淋巴结转移规律不同,但在上、下纵隔及腹部均有广泛转移。单因素分析结果显示,淋巴结转移与癌灶长度及浸润深度有关(P<0.05)。多因素分析结果表明,原发癌灶浸润深度和清扫淋巴结数目是淋巴结转移的独立预后因素。结论:食管癌McKeown术式及系统淋巴结清扫是目前治疗SMESC的最佳治疗手段。

Reduction Charge Smaller than the Deposited One in Cathodic Stripping Voltammograms of AgCl

A silver electrode was anodized in lowly concentrated potassium chloride solution almost under the steady state to generate a deposit of silver chloride on the electrode, and the deposit was cathodically stripped by linear potential scan to evaluate the reduction charge. Then the oxidation charge was larger than the reduction one. Since the equality was valid for long term chronocoulometry at the double potential step, the inequality is not due to any irreversibility of electrode reactions, but can be attributed to the process of the cathodic potential scan. A reason for the inequality is the negative charge of the capacitance involved in the electrode reaction, which has been observed in simple, dissolved redox species like a ferrocenyl derivative. The negative capacitive currents are conspicuous for high concentrations of redox species on the electrode because they result from the orientation of the dipoles of the redox species coupled with counterion, of which direction is opposite to that of the solvent dipoles. If a silver chloride film was thin enough to be regarded as a monolayer, we found that half of the cathodic stripping charge should be lost by the negative capacitance.

Study of the Value of Combined Multiorgan Resection in Surgical Treatment of Carcinoma of the Gastric Cardia

OBJECTIVE： To determine the value of resection of combined visceral organs in surgical treatment of gastric cardiac carcinoma. METHODS： We retrospectively analyzed 217 random patients with carcinoma of the gastric cardia who underwent a gastric cardiac resection. The patients had been treated as follows： 186 with partial gastrectomy, 31 with total gastrectomy, 97 with a combined-visceral resection, of which 82 underwent a splenectomy plus partial pancreatectomy, 10 with splenectomy alone and 5 with partial hepatectomy and diaphragmatectomy. RESULTS： The total patients were divided into 3 groups： 128 with a gastrectomy alone, 10 with gastrectomy and splenectomy, and 82 with gastrectomy and splenectomy plus pancreatectomy. The operating times for these 3 groups were respectively 3.0 h, 3.1 h and 3.8 h. The hospitalization times were respectively 23.8 d, 31.2 d and 25.9 d. No differences in post-operative complications were found between these 3 groups. There were 92 patients who underwent a gastrectomy combined with a splenectomy and （or） the pancreatectomy, in which 92 No.10 lymph nodes were eliminated, with an average of one in each patient. Among the 125 patients not receiving a splenectomy but with elimination of lymph nodes, 82 underwent a gastrectomy combined with partial pancreatectomy, of which 107 lymph nodes were eliminated for the No. 11 group, with an average of 1.3 in each patient. There was a statistically significant difference between the 2 groups. The overall survival rates were similar in the 3 groups showing no statistical differences, but was higher in the Stage Ⅲ patients with a combined resection of multi-organs. For patients in the Stage Ⅳ without resection of multi-organs, the survival rate was higher, but there was no significant difference between the 2 groups. CONCLUSION： It is difficult to determine precisely the involvement of para-tumorous organs with the eye during an operation. Combining a splenectomy with a pancreatectomy does not increase the post-operative complications following surgical treatment for carcinoma of the gastric cardia. The combination of a splenectomy and partial pancreatectomy results in a higher survival rate and has an important significance for eliminating the lymph nodes of group 10 and 11, especially for patients in Stage Ⅲ. In the application of a resection combining multi-organs, the doctor should make every effort to decrease the trauma and the complications based on the condition that the cancerous tissue is totally resected.

Quantization of Rough Set Based Attribute Reduction

We demonstrate rough set based attribute reduction is a sub-problem of propositional satisfiability problem. Since satisfiability problem is classical and sophisticated, it is a smart idea to find solutions of attribute reduction by methods of satisfiability. By extension rule, a method of satisfiability, the distribution of solutions with different numbers of attributes is obtained without finding all attribute reduction. The relation between attribute reduction and missing is also analyzed from computational cost and amount of solutions.

Silurian integrative stratigraphy,biotas,and paleogeographical evolution of the Qinghai-Tibetan Plateau and its surrounding areas

The Silurian palaeontology and stratigraphy of the Qinghai-Tibetan Plateau have been studied for more than100 years.With the launch of the Second Tibetan Plateau Scientific Expedition and Research,it is necessary to update the summaries of the Silurian stratigraphy and fossil assemblages of the Qinghai-Tibetan Plateau and their correlation with its surrounding areas.In this study,we have selected 33 sections from the Qinghai-Tibetan Plateau and its surroundings areas,summarised the available data in terms of stratigraphic regionalisation,lithostratigraphy,chronostratigraphy,and biostratigraphy,and divided the study area into four stratigraphic provinces:the Xizang-Western Yunnan-Western Sichuan Province,the KunlunQilian Province,the South China Province,and the Tarim Province.In general,the Silurian strata in the Qinghai-Tibetan Plateau is more complete than those in other areas of China.Palaeobiogeographical studies of the vertebrate faunas,sporomorph assemblages,and brachiopod faunas of the study area indicate a closer geographical relationship between the South China,Tarim,and Indochina palaeoplates,than previously considered.Compared with the surrounding areas where Silurian strata have been extensively studied,the study of Silurian strata in the main part of the Qinghai-Tibetan Plateau is still in the preliminary stage.In the future,it is necessary to conduct research on the age,distribution,and resource potential of basal Silurian black shales to provide new directions for shale gas exploration and development in China.The shallow marine strata of the middle to upper Silurian require further subdivision.Considering that the Silurian System in the Qinghai-Tibetan Plateau is more complete,it has the potential to supplement and improve the study of the carbon isotope stratigraphy of the Silurian in China.

Assessment of piloting behavior impact on landing risk of transport aircraft

The human factors and their interaction with other factors play an important role in the flight safety of transport aircraft.In this paper,a paradigm of risk assessment for transport aircraft interacting with piloting behaviors is proposed,with focus on landing which is the most accident-prone flight stage in aviation safety statistics.Model-based flight simulation serves as our data source for landing risk analysis under uncertainties.A digital pilot in the loop that reflects the human piloting behaviors is employed to facilitate simulation efficiency.Eight types of unsafe events in landing are identified from statistics.On this basis,the landing safety boundary is extracted via stochastic simulation to divide safety and hazardous flight status domains,which con-tributes to flight status management and risk warning.The simulation results indicate that appro-priate piloting behavior,which is active response and fast target acquisition with minimum overshoot and fluctuation,shows benefit to landing safety.The subset simulation technique is employed to further refine the boundary with less computational workload.Furthermore,the effect of airspeed,windspeed,and other factors on landing risk is also discussed.The proposed risk assess-ment method would help optimize operation procedure and develop targeted pilot training program.

BiVO_(4)/TiO_(2)制备与光催化性能的研究进展

目前针对TiO_(2)和BiVO_(4)的改性方法有很多,但是构建异质结是最为简单的一种优化措施之一.BiVO_(4)/TiO_(2)由于二者可以相互修饰,并且具有低成本、无毒、稳定的优点,被广泛应用于光催化领域.构建理想的BiVO_(4)/TiO_(2)异质结可以进一步推动复合材料在光催化领域的发展.本文首先从化学溶液法和物理沉积法出发阐述了常用的制备方法,主要包括水热法、溶胶凝胶法、原子沉积法、磁控溅射沉积以及脉冲激光沉积;基于此,介绍了BiVO_(4)/TiO_(2)在光催化降解、光催化分解水以及光催化还原CO_(2)中的应用及相关机理;然后,从质量分数比、晶面工程、形貌调控、助催化剂、元素掺杂等方面介绍了优化BiVO_(4)/TiO_(2)光催化性能的方法.通过对过去的相关研究进行整理与分析,旨在为BiVO_(4)/TiO_(2)这一类宽窄带隙半导体构成的复合光催化材料提供新的研究方向和思路.

Collecting and analyzing key-value data under shuffled differential privacy

1 Introduction Key-value data,as NoSQL data widely used in recent years,has been frequently collected and used for analysis in major websites and mobile apps.The frequency distribution estimation on the key domain,as well as the mean estimation of values associated with the same key,are crucial and worth billion dollars in the business.However,in real applications,the key-value records are submitted by terminal devices of different users.Directly collecting the information from users may pose serious risks on personal privacy.On the other hand,the emerging shuffled differential privacy(SDP)model[1]is proposed to collect sensitive data from users.