Along with the increasing uncertainty of the global economy and the spread of the new crown pneumonia epidemic, the risk challenges to economic development have increased significantly, and the risk ...of corporate debt defaults has become more pronounced. As an important component of the capital market, the bond market also began to experience credit bond defaults during this period. Since 2021 the global bond market has shown a sharp increase in defaults, with the default rate of non-state enterprise bonds significantly higher than the overall market, and the capital market has also ushered in a period of pain and accelerated credit risk release. Enterprises are on the verge of bankruptcy restructuring and urgently need the government to provide a bailout and stabilize the market. Therefore, this paper uses the financial data of Chinese listed companies from 2016-2021, constructs a relief intensity variable using the equity pledge rate of listed companies before the relief (2021), and empirically analyzes the impact of local government relief and financing cost on the default risk of listed companies using an intensity double difference model. The results of this study show that: (1) local government bailout significantly reduces the default rate of listed companies by 13%; (2) the effect of local government bailout varies significantly depending on whether listed companies have connected transactions with financing platform companies, and the increase of bailout intensity increases the return on assets of listed companies with related transactions with financing platform companies by 9.8%, which laterally reduces the default rate of corporate debt; (3) the cost of financing is an important mechanism by which local government bailouts affect the credit default rate of listed companies, with a regression correlation of 0.75; (4) the above effect is more pronounced in regions with a higher degree of marketization, with a 9% increase in the effect. The findings of this paper are important for actively managing the risk of dual corporate debt and credit defaults and enhancing the effectiveness of macroeconomic regulation during the epidemic period.
The oxygen evolution reaction (OER) has been explored extensively for reliable hydrogen supply to boost the energy conversion efficiency. The superior OER performance of newly developed non‐noble ...metal electrocatalysts has concealed the identification of the real active species of the catalysts. Now, the critical active phase in nickel‐based materials (represented by NiNPS) was directly identified by observing the dynamic surface reconstruction during the harsh OER process via combining in situ Raman tracking and ex situ microscopy and spectroscopy analyses. The irreversible phase transformation from NiNPS to α‐Ni(OH)2 and reversible phase transition between α‐Ni(OH)2 and γ‐NiOOH prior to OER demonstrate γ‐NiOOH as the key active species for OER. The hybrid catalyst exhibits 48‐fold enhanced catalytic current at 300 mV and remarkably reduced Tafel slope to 46 mV dec−1, indicating the greatly accelerated catalytic kinetics after surface evolution.
An irreversible phase transformation was tracked in situ from NiNPS to α‐Ni(OH)2. This result and potential‐dependent reversible conversion between α‐Ni(OH)2 and γ‐NiOOH prior to OER unveil the real active species of γ‐NiOOH in self‐reconstructed Ni‐based catalysts.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
This article presents an unambiguous evolutionary sequence of historical events leading to the development of customary international law, seen with reference to the mutual influence and ...transformation of legal philosophy, practice and codification on plundering cultural property during wars. The contemporary legal rules and customs working against taking cultural property as spoils of war are rooted in the eighteenth century, and were consistently developed in the nineteenth and twentieth centuries. Restitution appears the best remedy for the country of origin, especially in the condition where the plundered cultural property is existent and identifiable. Achieving this goal depends on the cooperation and coordination throughout the world, based on a wider customary international law space.
•A new corrected strain-rate enhancement model is proposed by introducing a time scale.•The new model captures delayed stress response of concrete under variations of strain-rate.•The multiple cracks ...and crack branching in concrete are well predicted using this new model.•The limitations of frequently-used instantaneous strain-rate enhancement model are addressed.
Dynamic tensile failure (e.g. spall) is frequently observed when concrete structures are subjected to blast and impact loadings, which is accompanied by the increase of tensile strength with increase of loading rate. Accurate prediction of dynamic tensile failure in concrete material is a challenging problem, in which the strain-rate effect should be properly considered. In the present study, a new corrected strain-rate enhancement model is proposed by introducing a time scale to control the evolution of strain-rate, as to capture the delayed stress response under variations of strain-rate. This corrected strain-rate enhancement model is then combined with the damage-based nonlocal model recently proposed by Kong et al. 18 to investigate the influence of strain-rate effect on numerical predictions of dynamic tensile failure. Numerical examples of a 1D spalling test demonstrate that the introduction of a time scale in the corrected strain-rate captures the delayed stress response and has a weak regularization effect. Three sets of experiments, namely, the Split-Hopkinson Tensile Bar (SHTB) test, the Modified Split-Hopkinson bar (spalling) test and the Compact Tension test, are numerically simulated using the proposed corrected strain-rate enhancement model and the frequently-used instantaneous strain-rate enhancement model. It is found that, considering the instantaneous strain-rate enhancement in the material model, the multiple cracks and crack branching cannot be well predicted, and the capability of energy absorption of concrete structures is overestimated, which may lead to an unsafe design. Promising predictions of dynamic tensile failures in concrete, including multiple cracks, crack branching and the structural resistance are obtained by the damage-based nonlocal model incorporating with the corrected strain-rate enhancement model.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract There is a need for better wound dressings that possess the requisite angiogenic capacity for rapid in situ healing of full-thickness skin wounds. Borate bioactive glass microfibers are ...showing a remarkable ability to heal soft tissue wounds but little is known about the process and mechanisms of healing. In the present study, wound dressings composed of borate bioactive glass microfibers (diameter = 0.4–1.2 μm; composition 6Na2 O, 8K2 O, 8MgO, 22CaO, 54B2 O3 , 2P2 O5 ; mol%) doped with 0–3.0 wt.% CuO were created and evaluated in vitro and in vivo. When immersed in simulated body fluid, the fibers degraded and converted to hydroxyapatite within ∼7 days, releasing ions such as Ca, B and Cu into the medium. In vitro cell culture showed that the ionic dissolution product of the fibers was not toxic to human umbilical vein endothelial cells (HUVECs) and fibroblasts, promoted HUVEC migration, tubule formation and secretion of vascular endothelial growth factor (VEGF), and stimulated the expression of angiogenic-related genes of the fibroblasts. When used to treat full-thickness skin defects in rodents, the Cu-doped fibers (3.0 wt.% CuO) showed a significantly better capacity to stimulate angiogenesis than the undoped fibers and the untreated defects (control) at 7 and 14 days post-surgery. The defects treated with the Cu-doped and undoped fibers showed improved collagen deposition, maturity and orientation when compared to the untreated defects, the improvement shown by the Cu-doped fibers was not markedly better than the undoped fibers at 14 days post-surgery. These results indicate that the Cu-doped borate glass microfibers have a promising capacity to stimulate angiogenesis and heal full-thickness skin defects. They also provide valuable data for understanding the role of the microfibers in healing soft tissue wounds.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The dynamic compressive behavior of concrete is closely associated with the specimen size effect and the coupling effect of strain rate and specimen size on the compressive properties is something ...there worthy studying for the development and application of coral aggregate concrete (CAC). A novel 3D mesoscale modelling approach taking the random characteristics of aggregates is developed for the numerical study in the present work. The specimen diameter of numerical cylinder with the slenderness of 1/2 varies from 50 mm to 200 mm, and the strain rate is within the range of 10−3–200s−1. Employing the 3D mesoscale model, the dynamic compressive responses of CAC, i.e., stress-strain relation, failure pattern and process, energy evolution process, etc. have been simulated and analyzed systematically. Both the effect of strain rate and specimen size have been qualitatively and quantitatively discussed. Through the comparison of numerical and existing test data, it is verified that the compressive behaviors of CAC under different conditions could be characterized and predicted using the 3D mesoscale model. In addition, all above-listed properties are related to the strain rate and specimen size at different degrees. The strain rate effect law on the CAC's strength and absorbed energy can be well expressed using a quadratic function and an exponential function, respectively. And the relationship between strength and specimen size can be mathematically formulated by a power function. Furthermore, a coupling effect law of strain rate and specimen size on the strength of CAC has been proposed and validated based on numerical and test data, which is meaningful for the properties prediction of CAC.
Display omitted
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Selective extraction of zinc from cadmium and manganese with the slug flow.•A membrane based separator was used to realize phase separation after extraction.•Separation enhancement of zinc can be ...achieved without any aqueous pH adjustment.•Separation factors are an order of magnitude higher than those in batch reactor.•The difference of kLa is account for the enhanced separation performance.
Selective extraction of zinc from sulphate effluents containing zinc, cadmium and manganese by liquid–liquid extraction with a capillary microreactor operating in the slug flow regime was elaborately investigated. Experiments were carried out at a flow rate ratio 1:1 of aqueous to organic phase, with a set-up consisting of a T-mixer connected to a PTFE capillary microreactor, and a subsequent membrane separator. The influences of extractant saponification degree, initial aqueous pH, residence time and mixture velocity on separation performance were studied, which indicated that separation enhancement of zinc from cadmium and manganese can be achieved by controlling the residence time and mixture velocity in the capillary microreactor without any aqueous pH adjustment. The βZn/Cd 2232.86 and βZn/Mn 1288.90 could be accomplished within 45 s in microfluidic extraction, whereas only 233.39 and 193.05 within 25 min in batch extraction, confirming the significant separation enhancement. Furthermore, the overall volumetric mass transfer coefficient kLa and overall mass transfer coefficient kL were also determined, high kLa of zinc (0.055 s−1–0.472 s−1) and low kLa of cadmium (0.009 s−1–0.076 s−1) and manganese (0.011 s−1–0.083 s−1) were responsible for the significant separation performance in the slug flow microfluidic system.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
High‐performance electrocatalysts are desired for electrochemical energy conversion, especially in the field of water splitting. Here, a new member of phosphate electrocatalysts, nickel metaphosphate ...(Ni2P4O12) nanocrystals, is reported, exhibiting low overpotential of 270 mV to generate the current density of 10 mA cm−2 and a superior catalytic durability of 100 h. It is worth noting that Ni2P4O12 electrocatalyst has remarkable oxygen evolution performance operating in basic media. Further experimental and theoretical analyses demonstrate that N dopant boosts the catalytic performance of Ni2P4O12 due to optimizing the surface electronic structure for better charge transfer and decreasing the adsorption energy for the oxygenic intermediates.
A new type of nickel metaphosphate nanocrystal electrocatalyst exhibits high oxygen evolution reaction performance due to exposed active facets. Experimental and theoretical analyses demonstrate that N doping further boosts the catalytic activity via modifying the electronic structure and facilitating the formation of OO bonding.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Six- to 8-kb mini-dystrophin genes are promising candidates for Duchenne muscular dystrophy (DMD) gene therapy. Several dual adeno-associated virus (AAV) mini-dystrophin vectors have been tested in ...dystrophin-deficient mice. Despite the encouraging preclinical results, none of the existing dual AAV vectors can restore sarcolemmal neuronal nitric oxide synthase (nNOS) expression. Localization of nNOS to the sarcolemma may greatly improve the therapeutic outcome in DMD (Lai, Y., Thomas, G.D., Yue, Y., et al. 2009. J. Clin. Invest. 119, 624-635). In this study, we developed a series of dual AAV expression vectors to express a synthetic minigene that carries the nNOS localization domain. To help validate dual vector reconstitution, we also included a FLAG tag and a GFP reporter at different ends of the minigene. These dual AAV vectors were packaged in Y445F tyrosine mutant AAV-6 and tested in dystrophin-null mdx4cv mice by direct muscle injection. All dual vectors expressed GFP/FLAG-tagged mini-dystrophin and restored sarcolemmal nNOS. However, the reconstitution efficiency was significantly different among different sets. The dual vector set YZ27/YZ22 yielded the highest transduction efficiency (∼90%). Further development of this set dual vector may lead to more effective DMD gene therapy.
As one of the main aerodynamic noise sources of high-speed trains, the pantograph is a complex structure containing many components, and the flow around it is extremely dynamic, with high-level ...turbulence. This study analyzed the near-field unsteady flow around a pantograph using a large-eddy simulation（LES） with high-order finite difference schemes. The far-field aerodynamic noise from a pantograph was predicted using a computational fluid dynamics（CFD）/Ffowcs Williams-Hawkings（FW-H） acoustic analogy. The surface oscillating pressure data were also used in a boundary element method（BEM） acoustic analysis to predict the aerodynamic noise sources of a pantograph and the far-field sound radiation. The results indicated that the main aerodynamic noise sources of the pantograph were the panhead, base frame and knuckle. The panhead had the largest contribution to the far-field aerodynamic noise of the pantograph. The vortex shedding from the panhead generated tonal noise with the dominant peak corresponding to the vortex shedding frequency and the oscillating lift force exerted back on the fluid around the panhead.Additionally, the peak at the second harmonic frequency was associated with the oscillating drag force. The contribution of the knuckle-downstream direction to the pantograph aerodynamic noise was less than that of the knuckle-upstream direction of the pantograph, and the average sound pressure level（SPL） was 3.4 dBA. The directivity of the noise radiated exhibited a typical dipole pattern in which the noise directivity was obvious at the horizontal plane of θ=0°,the longitudinal plane of θ=120°,and the vertical plane of θ=90°.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
PDF
