Why Local Bonds Failed to Sell

The Central Government is allowing all provincial governments to issue local bonds to help finance the construction of public welfare facilities. But so far investors haven’t shown much interest in the bonds-the first of their kind to be issued in China. Ni Xiaolin, a senior commentator at Xinhua News Agency, discusses why in the following article she wrote for Beijing Review.

Localized CO_2 laser bonding process for MEMS packaging

The packaging poses a critical challenge for commercialization of MEMS products. Major problems with the packaging process include degraded reliability caused by the excess stress due to thermal mismatch and altered performance of the MEMS device after packaging caused by thermal exposure. The localized laser bonding technique for ceramic MEMS packaging to address above-mentioned challenges was investigated. A continuous wave CO2 laser was used to locally heat sealing material for ceramic MEMS package lid to substrate bonding. To determine the laser power density and scanning speed, finite element analysis thermal models were constructed to simulate the localized laser bonding process. Further, the effect of external pressure at sealing ring on the bonding formation was studied. Pull testing results show that the scanning speed and external pressure have significant influence on the pull strength at the bonding interface. Cross-sectional microscopy of the bonding interface indicates that the packages bonded with relatively low scanning speed and external pressure conditions have higher bonding quality. This research demonstrates the potential of localized laser bonding process for ceramic MEMS packaging.

LOCALIZED STUDIES ON ELECTRONIC STRUCTURE AND CHEMICAL BOND FOR [NCCuS_2MoS_2]^(2-) CLUSTER

The canonical and locatized molecutar orbiters of [NCCuS_2NoS_2]^(2-) cluster were calculated by means of CNDO quantum chemistry method. Then the energy and properties of corresponding chemicat bonds were discussed, especially, Cu-Sb-No three center conjugated π bonds and No-St-No conjugated π bonds were accounted for.

Some Success Applications for Local-Realism Quantum Mechanics: Nature of Covalent-Bond Revealed and Quantitative Analysis of Mechanical Equilibrium for Several Molecules

With local realism quantum mechanics established, we can simply describe an extranuclear electron as a large-scale elastic ring with an elastic phase trajectory. Several small molecules can thus be strictly calculated through the logical method of establishing an accurate mechanical equilibrium equation describing the molecular structure, then solving the strict solutions of this mechanical equation and the corresponding wave equation. The results (bond length and dissociation energy) are in good agreement with observed results—i.e. if it is only coincidence, there should not be such a high probability of agreement between calculated and observed results. The method of local realism quantum mechanics is no longer the semi-empirical method. The method to calculate the electron pairing energy uses a linear regression of the ionization energy obtained through experiment. Nonetheless, it is exciting that there are diatomic molecules such as Na2, K2 and asymmetric HF molecules that possess a non-zero non-bonding electron number in the calculation examples. Moreover, the molecular structures are very intuitive, and the calculation method is much simpler than existing methods.

LOCAL CHEMISTRY AND THE COHESIVE STRENGTH OF GRAIN BOUNDARIES IN Ni_3Al

Local chemistry plays an important role in determining the cohesive strength of grain boundaries in Ni3Al. Doping with B increases the room temperature ductility and changes the fracture mode from intergranular to transgranular, while doping with Zr increases the ductility but leaves the fracture mode predominantly intergranular.Electron Energy Loss Spectroscopy (EELS) and Energy Dispersive X-ray Spectroscopy (EDS) were used to probe the changes in local bonding (and hence the cohesive strength) produced by changes in local chemistry at large angle boundaries in Ni3Al.In addition , small angle tilt boundaries were studied to correlate structure with Nienrichment at the interface. B segregation to Ni-rich grain boundaries was shown to make the bonding similar to that of the bulk, thereby increasing their fracture resistance. Ni-enrichment does not occur in the presence of Zr segregation to grain boundaries. Ni-enrichment to antiphase boundaries (APB) in small angle tilt boundaries lowers the APB energy by reducing the number of high energy Al-Al interactions across the interface. Ni-enrichment to large angle boundaries is expected to produce a similar effect on energy.

Numerical Study on the Stress–Strain Cycle of Thermal Self-Compressing Bonding

Thermal self-compressing bonding(TSCB) is a new solid-state bonding method pioneered by the authors. With electron beam as the non-melted heat source, previous experimental study performed on titanium alloys has proved the feasibility of TSCB. However, the thermal stress–strain process during bonding, which is of very important significance in revealing the mechanism of TSCB, was not analysed. In this paper, finite element analysis method is adopted to numerically study the thermal elasto-plastic stress–strain cycle of thermal self-compressing bonding. It is found that due to the localized heating, a non-uniform temperature distribution is formed during bonding, with the highest temperature existed on the bond interface. The expansion of high temperature materials adjacent to the bond interface are restrained by surrounding cool materials and rigid restraints, and thus an internal elasto-plastic stress–strain field is developed by itself which makes the bond interface subjected to thermal compressive action. This thermal self-compressing action combined with the high temperature on the bond interface promotes the atom diffusion across the bond interface to produce solid-state joints. Due to the relatively large plastic deformation, rigid restraint TSCB obtains sound joints in relatively short time compared to diffusion bonding.

Strength of Intramolecular Hydrogen Bonds

The concept of resonance-assisted hydrogen bonds(RAHBs)highlights the synergistic interplay between theπ-resonance and hydrogen bonding interactions.This concept has been well-accepted in academia and is widely used in practice.However,it has been argued that the seemingly enhanced intramolecular hydrogen bonding(IMHB)in unsaturated compounds may simply be a result of the constraints imposed by theσ-skeleton framework.Thus,it is crucial to estimate the strength of IMHBs.In this work,we used two approaches to probe the resonance effect and estimate the strength of the IMHBs in the two exemplary cases of the enol forms of acetylacetone and o-hydroxyacetophenone.One approach is the block-localized wavefunction(BLW)method,which is a variant of the ab initio valence bond(VB)theory.Using this approach,it is possible to derive the geometries and energetics with resonance shut down.The other approach is Edmiston’s truncated localized molecular orbital(TLMO)technique,which monitors the energy changes by removing the delocalization tails from localized molecular orbitals.The integrated BLW and TLMO studies confirmed that the hydrogen bonding in these two molecules is indeed enhanced byπ-resonance,and that this enhancement is not a result ofσconstraints.

Localized electronic states in gaps on hole-net structures of silicon

Hole-net structure silicon is fabricated by laser irradiation and annealing, on which a photoluminescence （PL） band in a the region of 650-750 nm is pinned and its intensity increases obviously after oxidation. It is found that the PL intensity changes with both laser irradiation time and annealing time. Calculations show that some localized states appear in the band gap of the smaller nanocrystal when Silo bonds or Si-O-Si bonds are passivated on the surface. It is discovered that the density and the number of Si=O bonds or Si-O-Si bonds related to both the irradiation time and the annealing time obviously affect the generation of the localized gap states of hole-net silicon, by which the production of stimulated emission through controlling oxidation time can be explained.

Bonding Characteristics of TiC and TiN

Using ab initio density functional theory calculations, the electron localization function (ELF) of typical transition metal carbide TiC and nitride TiN were computed and analyzed to reveal their nature of the chemical bonds. The ELF approach was initially validated through typical examples of covalent-bonding Diamond (C) and ionic-bonding sodium chloride NaCl. Our results clearly demonstrate the dominantly ionic bonding characteristics of TiC and TiN. It is also suggested that the high mechanical hardness of TiC and TiN can be explained without evoking strong covalence.

定位键指数用于含氧多环芳烃对斑马鱼胚胎的急性毒性预测

含氧多环芳烃化合物是一种在多环芳烃苯环上,含有一个或数个羰基氧原子的持久性污染物,它具有比亲代多环芳烃更强的毒性、致癌、致畸和致突变性,因此探究高效的研究方法来建立毒性数据库非常重要.为研究含氧多环芳烃对斑马鱼胚胎的急性毒性与其分子结构之间的定量结构-毒性关系,根据含氧多环芳烃分子中原子空间拓扑结构,提出了一种新的结构指数–定位键指数L,并分别计算了32个含氧多环芳烃化合物分子的电性拓扑态指数Em、电性距离矢量M_(n),分析优化筛选了电性拓扑态指数其中的E16、电性距离矢量其中的M_(14)、M_(21)和M_(32)作为结构描述符,将它们与定位键指数L有机结合,与含氧多环芳烃化合物对斑马鱼胚胎的生物毒性进行回归分析,以5种结构参数为输入变量点价值,神经网络结构采用5-3-1,建构了一种预测含氧多环芳烃急性毒性lgEC_(50)的神经网络模型,该预测模型的总相关系数R_(T)值达到较高的0.9826,对毒性的预测值与实验值两者之间的平均误差仅为0.112;结果表明,含氧多环芳烃的急性毒性与定位键指数、电性拓扑态指数、电性距离矢量等结构参数有良好的非线性关系.研究可为含氧多环芳烃的环境污染及生态风险评估提供理论指导.

Density function theoretical study on the complex involved in Th atom-activated C–C bond in C2H6

Density functional theory（DFT） calculations are performed to investigate the reactivity of Th atom toward ethane C–C bond activation.A comprehensive description of the reaction mechanisms leading to two different reaction products is presented.We report a complete exploration of the potential energy surfaces by taking into consideration different spin states.In addition,the intermediate and transition states along the reaction paths are characterized.Total,partial,and overlap population density of state diagrams and analyses are also presented.Furthermore,the natures of the chemical bonding of intermediate and transition states are studied by using topological method combined with electron localization function（ELF） and Mayer bond order.Infrared spectrum（IR） is obtained and further discussed based on the optimized geometries.

地方政府专项债促进了企业创新吗?

自2015年新《预算法》全面实施以来,一系列地方政府债务管理体制改革政策陆续推出。作为改革后政府举债投资的主要方式,地方政府专项债扩张对企业创新的影响是评估改革效果的重要依据。本文通过政策梳理和理论分析识别地方政府专项债影响企业创新的机理,基于2015—2020年地级市与上市公司匹配的面板数据,实证检验了地方政府专项债对本地企业创新的影响。研究发现:地方政府专项债通过提高地方基础设施投资效率、降低企业融资约束和实际税负水平来促进企业创新;对于集聚程度较低和财政透明度较低地区、融资约束较高和税费负担较高企业,地方政府专项债对企业创新促进效应较强。本文研究表明地方政府专项债能够有效提升经济效率,助力经济高质量发展。

省际地方政府债券信用风险及其溢出效应——基于图注意力网络模型的分析

本文基于复杂网络视角考察省际地方政府债券信用风险及其溢出效应。根据2016—2022年我国地方政府债务在二级市场的月度信用利差及其特征变量,识别了信用利差的变化情况,揭示了信用利差与债券相关指标之间的内在关联。采用图注意力网络模型对地方政府债券信用风险及其影响因素进行评估,考察各类因素在影响信用风险时的交互效应,以及这些因素如何通过复杂网络对地方政府债券信用风险产生直接和间接的影响。在此基础上,本文通过分析省际地方政府债券风险的溢出效应,识别出地方政府债务风险的省际传导机制和部分省份之间债务风险相互增强的特点。基于上述结论,本文从完善二级市场风险预警体系、增强风险溢入效应较强省份财政稳定性、提高风险溢出效应较强省份债务管理水平、建立风险传导网络监控以及协调省际债务发行机制等方面提出政策建议。

完善政府债务管理制度:问题与思路

政府适度举债具有促进经济增长、平抑经济周期波动的作用,但如果管理制度不完善,债务超出财政承受能力,则会制约经济可持续发展。完善政府债务管理制度是进一步全面深化改革、推进中国式现代化的关键一环。历经近十年的地方政府性债务治理,我国取得了防范地方政府隐性债务风险的显著成效,但仍然没有将其根除。究其原因,是因为地方政府财权事权不完全匹配、地方经济发展思路尚未转变、显性债务管理体制不健全、缺少隐性债务化解的长效机制等财政根本性、体制性的矛盾没有得到真正化解。进一步全面深化改革应当针对政府债务管理制度的核心问题,通过对地方政府债务的全口径监测监管、加快地方融资平台的转型改革、健全地方政府专项债券管理体制等措施,建立防范化解隐性债务风险的长效机制,加强财政可持续性,进而推动经济高质量发展。

我国绿色政府债券理念及实践探索

本文基于我国绿色主权债券与绿色地方政府债券发行规模逐渐扩大、信用利差逐年收窄等特点,分析认为实践中仍存在绿色政府债券融资能力有限、投向领域与认购人结构单一、可持续性发展资金有限,以及与国际标准对标有待进一步推进等问题。为此本文提出若干政策建议,包括补齐绿色政府债在发行与管理等环节中的短板,提高我国绿色政府债的项目绩效管理能力,实现绿色政府债券国际接轨等。

城商行参与、地方政府救助与城投债违约风险化解

地方政府的支持对于降低城投债违约风险具有重要意义。基于2015—2021年城投债地级市数据,采用OLS估计和工具变量法,分析城商行资源对城投债信用利差的影响。研究表明,地区金融资源和地方政府可支配金融资源能够显著降低当地城投债违约风险。异质性分析表明,城商行对城投债违约风险的降低效应仅在经济较发达和城商行资产富裕的地区存在。机制分析表明,第一例城投债的实质性违约强化了城商行资源对信用利差的降低效应,金融资源结构的“本地化”倾向对信用利差呈“倒U型”状态,城商行资源在降低城投风险方面具有财政金融二重属性。基于此,建议重视地区城商行建设,提升地方政府紧急救助能力,防止出现隐性债务“由点到面”的违约风险扩大化。

地方政府专项债券的金融风险:生成机制与规制路径

专项债券作为当前我国地方政府举债的最主要形式,由于实践运行与“项目制”财政逻辑有所偏离,其调适公共风险与财政风险、隔离金融风险与财政风险的作用正面临衰减困境,从而可能诱生系统性金融风险。专项债券金融风险的规制应落脚于项目风险治理,并依循系统联动逻辑而有序展开。首先,须推动专项债券发行权与地方发展权的充分匹配,通过优化“代举—使用”制度而协调举债权力,进而从专项债券的发行源头规范公共风险的财政对冲机制;其次,要促进地方政府举债权与项目投资权的深度协调,通过规范“管理—偿还”制度来夯实投资责任,为防止项目风险演化为财政风险,在专项债券的使用全程构塑阻断机制;最后,还应实行专项债券国家监管与市场约束的双向协同,通过健全“监督—参与”制度以落实多元共治,从而在专项债券的薄弱环节针对财政风险金融化的趋势设计防御机制。

套筒灌浆接头黏结滑移关系的精细有限元分析

为揭示套筒灌浆连接接头中钢筋和灌浆料间的黏结滑移关系,利用DIANA 10.3有限元软件建立接头试件的肋尺度精细有限元模型,并根据有限元分析结果对接头的局部黏结滑移关系进行研究。结果表明:套筒中钢筋黏结应力沿锚固长度大致呈马鞍形分布,加载端峰值随荷载增加逐渐内移;钢筋与灌浆料间相对滑移从钢筋自由端向加载端递增,超过屈服荷载后在加载端发生激增,并逐渐向里发展;局部黏结滑移曲线大致分为5个阶段,不同锚固位置处曲线的发展趋势大致相同,但其具体路径在发展程度和曲线特征值方面有一定差异;黏结锚固位置函数沿锚固长度大致呈“M”形分布且锚固自由端峰值大于加载端,是锚固位置和相对滑移的二元函数,建议用椭圆曲线和二次曲线进行拟合。该肋尺度精细化有限元模型可用于套筒灌浆连接接头的黏结滑移本构关系的进一步研究。

地方城投债增信效力比较研究

以2015—2022年城投债发行交易数据,实证检验不同增信方式对城投债信用评级、发行定价和利差的影响效果。研究发现,增信能显著提高城投债债项评级,但对于降低城投债发行定价存在分化。第三方专业担保平均降低城投债发行利率1.36%,抵质押担保和差额补偿不显著,而信用风险缓释(保护)工具使城投债发行成本上升约0.27%。此外,第三方专业担保能显著收窄城投债的信用利差和期限利差,抵质押担保、差额补偿和信用风险缓释(保护)工具等不显著。