BOUNDEDNESS OF THE HIGHER-DIMENSIONAL QUASILINEAR CHEMOTAXIS SYSTEM WITH GENERALIZED LOGISTIC SOURCE

This article considers the following higher-dimensional quasilinear parabolic-parabolic-ODE chemotaxis system with generalized Logistic source and homogeneous Neumann boundary conditions{ut=∇⋅(D(u)∇u)−∇⋅(S(u)∇v)+f(u),x∈Ω,t>0 vt=Δv+w−v,x∈Ω,t>0,wt=u−w,x∈Ω,t>0,in a bounded domainΩ⊂R^n(n≥2)with smooth boundary ∂Ω,where the diffusion coefficient D(u)and the chemotactic sensitivity function S(u)are supposed to satisfy D(u)≥M1(u+1)^−αand S(u)≤M2(u+1)^β,respectively,where M1,M2>0 and α,β∈R.Moreover,the logistic source f(u)is supposed to satisfy f(u)≤a−μu^γ with μ>0,γ≥1,and a≥0.Asα+2β<γ−1+2γ/n,we show that the solution of the above chemotaxis system with sufficiently smooth nonnegative initial data is uniformly bounded.

商誉减值规避、盈余管理与股价崩盘风险

本文选取我国2007-2016年A股市场有并购商誉的上市公司为研究样本,运用配对方法测量商誉减值规避,探讨公司管理者在面对审计师等内外部监督压力时会如何规避商誉减值,进一步研究管理者这种商誉减值规避行为是否会对公司未来股价崩盘风险产生影响。研究结果发现,相比计提商誉减值的公司,商誉减值规避的公司会进行更多向上的盈余管理(真实盈余管理和应计盈余管理)。这表明管理者会通过向上盈余管理活动调增当期会计盈余,缓解公司内外部对规避商誉减值的监督压力,避免自身利益因商誉减值而受到损害。进一步研究表明,并购商誉减值规避会显著提升公司股价崩盘风险,即相比计提商誉减值的公司,进行商誉减值规避的公司未来股价崩盘风险更高。本文的研究发现可为市场监管者如何监管公司管理者商誉减值决策、保证商誉会计准则得以有效执行、防范和化解公司股价崩盘风险、保护投资者利益提供有益的启示。

High-performance solar vapor generation of Ni/carbon nanomaterials by controlled carbonization of waste polypropylene

Solar vapor generation is emerging as a promising technology using solar energy for various applications including desalination and freshwater production.However,from the viewpoints of industrial and academic research,it remains challenging to prepare low-cost and high-efficiency photothermal materials.In this work,we report the controlled carbonization of polypropylene(PP)using NiO and poly(ionic liquid)(PIL)as combined catalysts to prepare a Ni/carbon nanomaterial(Ni/CNM).The morphology and textural property of Ni/CNM are modulated by adding a trace amount of PIL.Ni/CNM consists of cup-stacked carbon nanotubes(CS-CNTs)and pear-shaped metallic Ni nanoparticles.Due to the synergistic effect of Ni and CS-CNTs in solar absorption,Ni/CNM possesses an excellent property of photothermal conversion.Meanwhile,Ni/CNM with a high specific surface area and rich micro-/meso-/macropores constructs a threedimensional(3 D)porous network for efficient water supply and vapor channels.Thanks to high solar absorption,fast water transport,and low thermal conductivity,Ni/CNM exhibits a high water evaporation rate of 1.67 kg m^-2 h^-1,a solar-to-vapor conversion efficiency of 94.9%,and an excellent stability for 10 cycles.It also works well when converting dyecontaining water,seawater,and oil/water emulsion into healthy drinkable water.The metallic ion removal efficiency of seawater is 99.99%,and the dye removal efficiency is>99.9%.More importantly,it prevails over the-state-of-art carbonbased photothermal materials in solar energy-driven vapor generation.This work not only proposes a new sustainable approach to convert waste polymers into advanced metal/carbon hybrids,but also contributes to the fields of solar energy utilization and seawater desalination.

Can material asset reorganizations affect acquirers' debt financing costs?——Evidence from the Chinese Merger and Acquisition Market

In this paper, we investigate whether material asset reorganizations(MARs), a special form of merger and acquisition(M&A) transactions, can affect the acquirers' cost of debt financing. Further, we examine the effect of acquiring firms' accounting information quality on the cost of debt and on the association between MARs and debt costs. We predict that compared to conventional M&As, large-scale acquisitions through MARs can generate a much greater influx of assets from target firms. This raises the acquirers' asset collateral and thus reduces the cost of debt. Because the quality of accounting information is a key factor affecting the cost of debt, we suggest that it has a spillover effect on the debt-cost effect of MARs. Using M&A transactions by listed companies in the Chinese A-share market from 2008 to 2014 as our sample, we find that MARs are associated with a higher asset collateral and lower ex post cost of debt than conventional M&As. Furthermore, we show that the acquiring firms' accounting information quality has a significant negative effect on debt costs, and the negative association between MARs and the cost of debt is more pronounced when accounting information quality is higher.

The potential harms of goodwill impairment avoidance: Evidence based on future performance and stock prices

The rapidly increasing volume of goodwill assets in the capital market generates potential risks due to the possibility of an untimely recognition of goodwill impairment.In this paper,we investigate the financial consequences of goodwill impairment avoidance based on firms’future performance and stock prices.Using Chinese A-share listed firms with goodwill balances,we find that avoiding goodwill impairments negatively affects a firm’s performance growth and increases its risk of a future stock price crash.These adverse effects continue for the three years following the goodwill impairment avoidance.Our results indicate that goodwill impairment avoidance has detrimental impacts on a firm’s future performance and stock price and that these impacts are persistent.Our conclusions are helpful for regulators on how to prevent the risks hidden in goodwill impairment recognition and maintain the stable development of the financial market.

Identifying M&A targets and the information content of VC/PEs

The information gap in the M&A market hinders acquirers from effectively identifying high-quality targets. We examine whether VC/PEs convey information content in the M&A market and whether acquirers can use such information to identify high-quality targets. We show that VC/PEs have significant information content and can signal high-quality target companies via ‘‘certification". When acquirers lack acquisition experience and targets are located in inferior information environments, VC/PE ‘‘certification" is more significant.The better reputation a VC/PE has, the more information it conveys. Syndicate VC/PEs convey stronger information than independent VC/PEs. We also find that acquirers do not pay higher premiums for high-quality targets. Overall, our results suggest that VC/PEs have value relevance in the M&A market,confirming their ‘‘certification" role. We present means for acquirers to select high-quality targets and investors to build efficient portfolios.

Polymer Synthesis Based on Self-Accelerating 1,3-Dipolar Cycloaddition Click Reactions

This review reports our recent work on developing polymer synthesis methods based on a self-accelerating double-strain-promoted 1,3-dipole-alkyne cycloaddition(DSPDAC)click reaction.In DSPDAC,the cycloaddition of 1,3-dipole with the first alkyne of sym-dibenzo-1,5-cyclooctadiene-3,7-diyne(DIBOD)activates the second unreacted alkyne,which reacts with 1,3-dipole much faster than the original alkyne of DIBOD.When using DIBOD and bis-dipole compounds as monomer pairs,the self-accelerating property of DSPDAC allows us to develop a stoichiometric imbalance-promoted step-growth polymerization method.It could produce polymers with ultrahigh molecular weight in the presence of excess DIBOD monomers.When using DIBOD to ring-close linear polymers with 1,3-dipole end groups,the self-accelerating property of DSPDAC facilitates us to develop a unique bimolecular ring-closure method.It could efficiently prepare pure cyclic polymers in the presence of excess DIBOD small linkers to linear polymer precursors.

Reward meritocracy or nepotism: The case of independent financial advisors appointed by Chinese listed companies

As independent financial advisors, securities firms are the core intermediaries in major asset reorganization(MAR) of listed companies.Furthermore, they play the dual roles of transaction and authentication.Based on this institutional background, this paper studies how listed companies choose between industry experience(‘‘meritocracy') and relationships(‘‘nepotism').Using the MAR of A-share listed companies from 2008 to 2013 as the sample, this paper shows that higher transaction costs(i.e., greater demand for the transaction function of advisors) are related to the higher possibility of advisors with weaker relationships and more industry experience being hired.It also shows that higher suspicion of tunneling(i.e., greater demand for the signal of fairness associated with advisors’ authentication function) is related to the higher possibility of advisors with weaker relationships being hired, but it is not significantly related to whether advisors have more or less industry experience.This paper also shows that reputation has a certain governance effect on the negative consequences of relationship.For the most part, listed companies reward meritocracy but not nepotism when appointing independent financial advisors.

The role of accounting conservatism in M&A target selection

Mergers and acquisitions(M&As)are among the most important investment activities for companies,but they contain great risks.We investigate the role of accounting conservatism in M&A target selection and risk.We find that for risk-averse reasons,firms with high accounting conservatism are likely to acquire profitable targets and avoid loss-making targets.When such firms acquire loss-making targets,the conservatism’s risk-control role reduces M&A risk and increases M&A performance,but only when control of the target is transferred and the acquirer has high long-term debt and low management power.Furthermore,accounting conservatism reduces risk by increasing the maturity match between cash flow and debt.Our results suggest that accounting conservatism plays not only a risk-averse role but also a riskcontrol role,providing new evidence for the usefulness of accounting conservatism in M&A decisions.