市场化债转股与股价崩盘风险研究

文章以2010—2020年沪深两市A股非金融类上市公司为样本,研究市场化债转股企业对于股价崩盘风险的影响以及作用机制。研究发现:市场化债转股企业相对于非市场化债转股企业而言,其企业股价崩盘风险较低,且市场化债转股后能降低企业股价崩盘风险。进一步研究表明,市场化债转股通过缓解融资约束和降低融资成本的中介作用能降低企业股价崩盘风险。以上结论一方面丰富了股价崩盘风险、市场化债转股等相关领域的文献,另一方面对企业推动供给侧结构性改革在公司治理中的作用提供了一定的经验,对优化股权结构、降低股价崩盘风险也具有一定的参考价值。

异步联网后的云南电网中PSS2B增益改进

目前云南电网部分机组存在双输入型电力系统稳定器(PSS2B)高频段增益限制中低频段增益的问题,提出新型的PSS2B(New-PSS2B),目的是增大中低频段的增益,并减少高频段对中低频段增益的限制。在PSASP用户自定义模型(UDM)中搭建New-PSS2B自定义模型,通过研究分析改进前后PSS2B模型的增益,发现采用New-PSS2B有效提高了中低频段增益。基于PSASP仿真软件,在单机无穷大系统中调用NewPSS2B模块,通过仿真验证了New-PSS2B在中低频段各个频率点抑制低频振荡的效果都优于原有的PSS2B,说明了New-PSS2B具有在全频段都能提供合适阻尼的能力,也能满足电网抑制低频振荡的要求。

基于轨迹特征根的系统暂态稳定判断与扰动类型筛选方法

为了解决系统暂态稳定性判断的准确性以及扰动类型筛选的快速性问题,提出了一种基于轨迹特征根数据的暂态稳定性筛选方法。该方法建立了高阶系统的线性化模型,该模型考虑励磁和调速系统等主要元件对线性化模型的影响。励磁系统和调速系统模型利用拉普拉斯逆变换实现在非平衡点处的线性化处理。接着,提出一种基于扰动后轨迹特征根波动方差的扰动类型识别方法,该方法引用方差对扰动后的轨迹特征根数据计算振荡和离散程度,并以此量化指标,根据波动方差值识别扰动类型。最后通过算例,验证了文中设置的扰动类型与识别的结果基本一致。

Predicting the present-day in situ stress distribution within the Yanchang Formation Chang 7 shale oil reservoir of Ordos Basin, central China

The Yanchang Formation Chang 7 oil-bearing layer of the Ordos Basin is important in China for producing shale oil.The present-day in situ stress state is of practical implications for the exploration and development of shale oil;however,few studies are focused on stress distributions within the Chang 7 reservoir.In this study,the present-day in situ stress distribution within the Chang 7 reservoir was predicted using the combined spring model based on well logs and measured stress data.The results indicate that stress magnitudes increase with burial depth within the Chang 7 reservoir.Overall,the horizontal maximum principal stress(SHmax),horizontal minimum principal stress(Shmin) and vertical stress(Sv) follow the relationship of Sv≥SHmax>Shmin,indicating a dominant normal faulting stress regime within the Chang 7 reservoir of Ordos Basin.Laterally,high stress values are mainly distributed in the northwestern parts of the studied region,while low stress values are found in the southeastern parts.Factors influencing stress distributions are also analyzed.Stress magnitudes within the Chang 7 reservoir show a positive linear relationship with burial depth.A larger value of Young's modulus results in higher stress magnitudes,and the differential horizontal stress becomes higher when the rock Young's modulus grows larger.

OPD-ScanⅢ测量角膜屈光力和散光的可重复性及其与Pentacam检测结果的一致性

目的分析OPD-ScanⅢ测量角膜屈光力及散光的可重复性及其与Pentacam检测结果的一致性。方法采用诊断试验研究方法,收集2018年8月于南通大学第二附属医院及苏州大学附属理想眼科医院就诊的屈光不正患者50例100眼,采用主觉验光测量受检者球镜度数、散光度数及轴位。分别采用OPD-ScanⅢ和Pentacam行角膜生物测量且连续测量3次,记录平坦轴角膜曲率(K1)、陡峭轴角膜曲率(K2)、散光度数、散光轴位、散光矢量参数J0(0°或180°轴位的Jackson交叉柱镜值)、J45(45°轴位的Jackson交叉柱镜值)。采用组内相关系数(ICC)评价2种仪器测量数据的可重复性。分别采用Wilcoxon符号秩检验、Spearman秩相关性分析和Bland-Altman图表法分析2种仪器测量数据的差异、相关性及一致性。结果OPD-ScanⅢ测得K1、K2、散光度数及轴位、J0以及J45的ICC均>0.900;Pentacam测得散光度数的ICC为0.896,其余测量数据均ICC>0.900。OPD-ScanⅢ测量K2、散光度数、J0及J45值明显高于Pentacam测量值,差异均有统计学意义(均P<0.05)。OPD-ScanⅢ测量K1、K2、散光度数及轴位、J0和J45值与Pentacam的测量值均呈正相关(r s=0.981、0.982、0.900、0.737、0.921、0.703,均P<0.01)。OPD-ScanⅢ与Pentacam测量K1、K2、散光度数及轴位、J0及J45差值的95%一致性界限(LOA)分别为-0.52~0.50 D、-0.39~0.59 D、-0.37~0.48 D、-17.29°~20.38°、-0.12~0.24 D和-0.22~0.28 D。结论OPD-ScanⅢ在测量高度角膜散光患者的角膜屈光力及角膜散光度数时具有较好的可重复性和准确性,其测量散光轴位的95%LOA较大,不能被临床所接受。

钢筋套筒灌浆连接技术在高铁装配式桥墩的应用研究

以京雄城际铁路固霸特大桥为案例,对几种桥墩拼装方法进行比较分析,确定采用灌浆套筒进行装配式桥墩连接,并对其施工工艺进行了介绍。研究表明,钢筋套筒灌浆连接适用于高铁桥墩装配式施工,大幅提高施工效率,是一种高效、环保的连接方式。

Preparation and <i>in Vitro</i>Drug Release Evaluation of Once-Daily Metformin Hydrochloride Sustained-Release Tablets

The objective of this study was to develop once-daily metformin hydrochloride sustained-release tablets (MHSRT) and evaluate their in vitro release behavior. MHSRT were prepared by the film coating method. The in vitro drug release rate of MHSRT and the commercial tablets Fortamet? made in the United States of America in water was fitted with zero order kinetic equation, and Ritger-Peppas kinetic equation in 0.1 M HCl and pH 6.8-phosphate buffer, respectively. The similarity factor f2 values of MHSRT in three different dissolution medium were 82, 80 and 74, respectively in comparison with imported Fortamet?, which were all greater than 50. The results of storage-stability showed that MHSRT were stable for at least 6 months under stress condition (40℃ ± 2℃, RH 75% ± 5%). Therefore, in this study, MHSRT were successfully prepared using optimized formulation technologies that meet mass produce. The in vitro release behavior of MHSRT was almost similar to that of imported Fortamet?.

桥梁索体下端预埋管防水材料组合填充技术

拉索是斜拉桥等桥型的重要承载构件,其耐久性直接影响桥梁的安全。调查发现,拉索腐蚀成为该类桥梁的主要病害,其主要原因是索体下端防水未达到设计要求,防水效果差。笔者结合拉索结构的受力特点、性能要求及其构造特点,提出了一种拉索预埋管组合材料(OVM阻蚀密封蜡、防腐聚氨酯、聚硫化防腐密封胶)填充技术方案,工程应用表明,该技术达到了拉索预埋管防水、防腐、减振等性能要求,并具有良好的经济性。对类似工程具有一定的参考价值。

First principles study of interactions of oxygen–carbon–vacancy in bcc Fe

Behaviors of C or O in bcc Fe and interactions of C-O and oxygen-carbon-vacancy(O-C-□) are investigated by first principles calculations. Octahedral interstitial site is the most stable position for an O atom in bcc Fe. The migration energy of an O atom in bcc Fe is 0.46 eV. The strength of O-Fe(1 nn) bond(0.32) is slightly greater than that of Fe-Fe metallic bond(0.26). Repulsive interactions of C-C, O-O, and C-O exist in bcc Fe. When the concentration of FIA(FIA refers to C or O) is relatively high, a vacancy can attract four FIAs and form stable FIAs-□ complex.

Exact solutions of the Schrodinger equation for a class of hyperbolic potential well

We propose a new scheme to study the exact solutions of a class of hyperbolic potential well.We first apply different forms of function transformation and variable substitution to transform the Schrodinger equation into a confluent Heun differential equation and then construct a Wronskian determinant by finding two linearly dependent solutions for the same eigenstate.And then in terms of the energy spectrum equation which is obtained from the Wronskian determinant,we are able to graphically decide the quantum number with respect to each eigenstate and the total number of bound states for a given potential well.Such a procedure allows us to calculate the eigenvalues for different quantum states via Maple and then substitute them into the wave function to obtain the expected analytical eigenfunction expressed by the confluent Heun function.The linearly dependent relation between two eigenfunctions is also studied.

Timing analysis of the black hole candidate EXO 1846–031 with Insight-HXMT monitoring

We present the observational results from a detailed timing analysis of the black hole candidate EXO 1846-031 during its outburst in 2019 with the observations of Insight-HXMT,NICER and MAXI.This outburst can be classified roughly into four different states.Type-C quasi-periodic oscillations(QPOs)observed by NICER(about 0.1-6 Hz)and Insight-HXMT(about 0.7-8 Hz)are also reported in this work.Meanwhile,we study various physical quantities related to QPO frequency.The QPO rms-frequency relationship in the energy band 1-10 keV indicates that there is a turning pointing in frequency around2 Hz,which is similar to that of GRS 1915+105.A possible hypothesis for the relationship above may be related to the inclination of the source,which may require a high inclination to explain it.The relationships between QPO frequency and QPO rms,hardness,total fractional rms and count rate have also been found in other transient sources,which can indicate that the origin of type-C QPOs is non-thermal.

桥梁钢丝拉索检测与维护关键技术

从新方法、新设备、新工艺、新材料角度重点介绍了桥梁钢丝拉索自由段和锚固区的检测与维护成套关键技术,为适应复杂条件下的桥梁拉索管养提供一定的参考。

Dental plaque-inspired versatile nanosystem for caries prevention and tooth restoration

Dental caries is one of the most prevalent human diseases resulting from tooth demineralization caused by acid production of bacteria plaque.It remains challenges for current practice to specifically identify,intervene and interrupt the development of caries while restoring defects.In this study,inspired by natural dental plaque,a stimuli-responsive multidrug delivery system(PMs@NaF-SAP)has been developed to prevent tooth decay and promote enamel restoration.Classic spherical core-shell structures of micelles dual-loaded with antibacterial and restorative agents are self-assembled into bacteria-responsive multidrug delivery system based on the pH-cleavable boronate ester bond,followed by conjugation with salivary-acquired peptide(SAP)to endow the nanoparticle with strong adhesion to tooth enamel.The constructed PMs@NaF-SAP specifically adheres to tooth,identifies cariogenic conditions and intelligently releases drugs at acidic pH,thereby providing antibacterial adhesion and cariogenic biofilm resistance,and restoring the microarchitecture and mechanical properties of demineralized teeth.Topical treatment with PMs@NaF-SAP effectively diminishes the onset and severity of caries without impacting oral microbiota diversity or surrounding mucosal tissues.These findings demonstrate this novel nanotherapy has potential as a promising biomedical application for caries prevention and tooth defect restoration while resisting biofilm-associated diseases in a controlled manner activated by pathological bacteria.

Five-year in-orbit background of Insight-HXMT

Purpose We present the five-year in-orbit background evolution of Insight-HXMT since the launch,as well as the effects of the background model in data analysis.Methods The backgrounds of the three main payloads,i.e.,low-energy telescope,medium-energy telescope,and high-energy telescope,are described.The evolution of the background over time is obtained by simply comparing the background in every year during the in-orbit operation of Insight-HXMT.Results The major observational characteristics of the Insight-HXMT in-orbit background are presented,including the light curve,spectrum,geographical distribution,and long-term evolution.The systematic error in background estimation is investigated for every year.Conclusion The observational characteristics of the five-year in-orbit background are consistent with our knowledge of the satellite design and the space environment,and the background model is still valid for the latest observations of Insight-HXMT.

ICL植入术后拱高预测的研究进展

拱高是评价有晶状体眼后房型人工晶状体(implantable collamer lens,ICL)植入术后安全性的重要指标,也是该手术研究的热点及焦点。ICL尺寸的选择是术后拱高最重要的可控因素。最传统的ICL尺寸选择方法是通过白到白及前房深度来进行选择,然而该方法准确性并不高。因此,研究者们不断尝试通过超声生物显微镜、前节OCT甚至人工智能等方法来进行术后拱高的预测及ICL尺寸的选择,并取得了一定的成果。本文尝试对于各种拱高预测及ICL尺寸选择方法进行比较分析,来阐述各种方法的特点效果及演变历程。

Phase Field Simulation for Grains Evolution of 17-4PH Steel During Cyclic Heat Treatment

A phase field model is developed to simulate the grain evolution of 17-4PH steel during cyclic heat treatment （CHT）. Our simulations successfully reproduce the grain morphologies of every CHT. In the process of every CHT, phase transformation recrystallization happens. The recrystallized grains appear mainly on the original grain boundaries. The average grain size of 13.2 μm obtained by 1040 ℃×1 h solution treatment for this experimental steel can be refined to 2.2 μm after five CHT＇s. Furthermore, the effects of phenomenological parameters in our model are discussed.

Relevance of placental type I interferon beta regulation for pregnancy success

Pregnancy is a unique immunologic and microbial condition that requires an adequate level of awareness to provide a fast and protective response against pathogens as well as to maintain a state of tolerance to paternal antigens.Dysregulation of inflammatory pathways in the placenta triggered by pathogens is one of the main factors responsible for pregnancy complications.Type I IFNs are key molecules modulating immune responses at the level of the placenta and are crucial for protection of the pregnancy via their antiviral and immune modulatory properties.In this study,we elucidate the mechanisms controlling the basal expression of IFNβand its negative feedback.Using in vitro and in vivo animal models,we found that TLR signaling maintains basal IFNβlevels through the TLR4-MyD88-independent TBK/IRF3 signaling pathway.We describe the role of the TAM receptor Axl in the regulation of IFNβfunction in human and mouse trophoblast cells.The absence of TAM receptors in vivo is associated with fetal demise due to dysregulation of IFNβexpression and its pro-apoptotic downstream effectors.Collectively,our data describe a feedback signaling pathway controlling the expression and function of IFNβin the trophoblast that is essential for an effective response during viral and microbial infections.

Prediction of natural fracture in shale oil reservoir based on R/S analysis and conventional logs

Investigation into natural fractures is extremely important for the exploration and development of low-permeability reservoirs.Previous studies have proven that abundant oil resources are present in the Upper Triassic Yanchang Formation Chang 7 oil-bearing layer of the Ordos Basin,which are accumulated in typical low-permeability shale reservoirs.Natural fractures are important storage spaces and flow pathways for shale oil.In this study,characteristics of natural fractures in the Chang 7 oil-bearing layer are first analyzed.The results indicate that most fractures are shear fractures in the Heshui region,which are characterized by high-angle,unfilled,and ENE-WSW-trending strike.Subsequently,natural fracture distributions in the Yanchang Formation Chang 7 oil-bearing layer of the study area are predicted based on the R/S analysis approach.Logs of AC,CAL,ILD,LL8,and DEN are selected and used for fracture prediction in this study,and the R(n)/S(n)curves of each log are calculated.The quadratic derivatives are calculated to identify the concave points in the R(n)/S(n)curve,indicating the location where natural fracture develops.Considering the difference in sensitivity of each log to natural fracture,gray prediction analysis is used to construct a new parameter,fracture prediction indicator K,to quantitatively predict fracture development.In addition,fracture development among different wells is compared.The results show that parameter K responds well to fracture development.Some minor errors may probably be caused by the heterogeneity of the reservoir,limitation of core range and fracture size,dip angle,filling minerals,etc.

Crystallographic Texture Evolution of ■-Fe_4N and Its Influences on Tribological Property of Nitrided Steel

The crystallographic texture of γ′-Fe4N in compound layer and its influences on the tribological properties of nitrided steel 38CrMoA1 are investigated in the study.The preferred orientation of（200）γ′is produced by low-temperature nitriding in atmosphere with low nitrogen-hydrogen ratio and increases with the nitriding time.The preferred orientation of（220）γ′appears after 72 h cyclic nitriding.The orientation relationships（0001）ε,/（101）α′,and[ll0]J/[111]γ′（Ill）γ′/（0001）α′ and[011]γ′//[1210]ε,（200）γ′//（l10）α′,and[011]γ′//[111]α′,as well as（1T03）J（220）γ′,and[0100]J/[110]γ′,are established by first-principles method.The misfit of interatornic distance（δ）,determining the phase transition resistance,is calculated.Accordingly,two reaction pathways during nitriding,and α′→γ′and α′→ε→γ′,are assumed,which determines the preferred orientations of γ′-Fe4N.Results of wear tests demonstrate that the specimen with preferred orientation of（200）γ′ exhibits lower frictional coefficient and lower wear rate in comparison with the specimen with（220）γ′ preferred orien-tation.（111）γ′ texture usually relates to the lower frictional coefficient but higher wear rate due to the main slip system parallel to the sliding plane.Therefore,the（200）γ′ preferred orientation has a positive significance in improving the wear properties of steels.

On Integrals Involving Universal Associated Legendre Polynomials and Powers of the Factor (1-x^2) and Their Byproducts

The associated Legendre polynomials play an important role in the central fields,but in the case of′the non-central field we have to introduce the universal associated Legendre polynomials P^m'l_′(x) when studying the modified Pschl-Teller potential and the single ring-shaped potential.We present the evaluations of the integrals involving the universal associated Legendre polynomials and the factor(1-x^2)^(-p-1) as well as some important byproducts of this integral which are useful in deriving the matrix elements in spin-orbit interaction.The calculations are obtained systematically using some properties of the generalized hypergeometric series.