Push-back Effect Research Articles

Does climate policy uncertainty impair or improve corporate investment efficiency?

Climate policy uncertainty (CPU) has been a topical issue given its widespread impacts, but its effect on corporate investment efficiency is arguable. Based on a sample of Chinese listed firms, we find that higher CPU results in lower investment levels while higher investment sensitivity to investment opportunities. This suggests that CPU improves investment efficiency by pushing firms to reduce investment expenditures and align their investment decisions more in line with investment opportunities. We name this finding as the pushback effect of CPU and find that it is more pronounced for firms with overinvestment or tight financial conditions.

Research on the Optimal Design of Retaining Piles of a Wide Metro Tunnel Foundation Pit Based on Deformation Control

Engineers pay more and more attention to the economic benefits of foundation pit engineering. At present, the optimal design of the foundation pit supporting structure mainly focuses on strength and functional design, and there is no mature theoretical design method for deformation control. In this paper, a method for calculating the overall deformation of a foundation pit supporting structure based on the principle of minimum potential energy is proposed. Based on this method, the optimal design of the foundation pit of Guangzhou Baiyun District Comprehensive Transportation Hub Metro Station is realized. The deformation calculation results and optimization design scheme are validated by finite element numerical simulation and field monitoring data. The results show that the proposed theoretical algorithm predicts the pile deformation curves better than the finite element method, suggesting the proposed theoretical method is reasonable and the optimization scheme of the retaining pile is feasible. In the optimized design, the deformation of the foundation pit retaining pile is controlled by its push-back effect. The proposed deformation calculation method can realize the overall deformation calculation of the foundation pit supporting structure.

Assessing the moderating effect of environmental regulation on the process of media reports affecting enterprise investment inefficiency in China

To achieve the triple goals of digesting excess capacity, making effective investments, and accelerating green governance, it is important and necessary to comprehensively examine the intrinsic relationship between media reports, environmental regulation, and enterprise investment inefficiency. To this end, this study employs multiple econometric models to investigate the intrinsic relationship between them by using the data of listed companies in China’s A-share heavy-polluting industries between 2010 and 2020. The results of the study are as follows. Firstly, media reports can encourage heavy-polluting enterprises to pay attention to stakeholder demands and significantly ameliorate the enterprise investment inefficiency. In addition, environmental regulation can ameliorate the enterprise investment inefficiency through the “push-back effect” and “compensation effect”. Moreover, pollution fees can positively moderate the amelioration effect of media reports on the investment inefficiency of heavy-polluting enterprises, while it fails in terms of environmental protection subsidies. Finally, conclusions and policy implications are provided.

Ultrafast extraction of cold brew coffee in a planetary rotating bed reactor: A kinetic study on the pushback effect

AbstractGiven the rising demand for cold brew coffee, innovative approaches are required to address the present difficulties in its production. This motivates the consideration of the planetary rotating bed reactor (PRBR) as a solid–liquid extraction technology. The PRBR consists of cylindrical mesh chambers that contain the solid phase and move in two superimposed rotations. This motion pattern enhances mass transfer through alternating radial forces: the pushback effect (PBE). To evaluate the utility of the PRBR and the role of PBE, we investigated the kinetics and energy demand of cold brew coffee extraction. For this purpose, we varied rotational speeds and PBE conditions in a 1 L lab‐scale reactor. Kinetics was determined by in‐line monitoring of electrical conductivity correlated with the eluate's weight‐based total dissolved solids and caffeine by high‐performance liquid chromatography. Energy consumption was derived from strain gauge torque measurements. Our findings reveal that saturation of the extraction rate with respect to the rotational speed is evident both with and without PBE. However, PBE significantly reduces extraction time by 75% while requiring 60% less mechanical energy. The fastest conditions probed 95% of the maximum extraction yield within 12 s, effectively being >99% faster than static immersion. We believe these findings, along with further procedural advantages, qualify the PRBR as a viable technology for cold brew coffee production.Practical ApplicationsThe relevance of an economical and sustainable preparation of cold brew coffee extends from the industrial to the gastronomic to the domestic environment. Challenges and limitations relate to process time, particle separation, product and extraction yield, and taste problems due to over‐extraction. The planetary rotating bed reactor (PRBR) promises to address all these issues by combining extraction and separation in a simultaneous and ultrafast process. The present study confirms the superiority of PRBR's action mechanisms in terms of rapidity and energetic efficiency for extraction. Due to the excellent scalability of both the design and the physical effect, the PRBR is intended for large‐scale production of ready‐to‐drink products and local production in coffee shops or private households. By modifying the particle feed, even continuous operation is conceivable. Further applications are, for example, dry‐hopping of beer, fast‐aging of spirits, and preparation of various liquid foods.

Can green transformation finance contribute to urban carbon emission performance? An empirical analysis based on a spatiotemporal bi-fixed SPDM model.

"Carbon peaking" and "carbon neutrality" are serious challenges at this stage, and the function of the green transformation finance (GTF) in the operation of carbon dioxide emission reduction is an urgent issue to be explored. However, empirical studies on GTF and carbon emission performance (CEP) are lacking. Given that, this research employs a panel dataset of 278 cities in China spanning the years 2006 to 2020 to measure the CEP of Chinese cities using the non-radial directional distance function (NDDF) approach and applies the SPDM and the intermediary effect model to practically analyze the spatial effects and mechanisms of GTF in promoting CEP. The findings derived from the empirical analysis indicate that (1) the level of GTF and CEP shows a trend of year-on-year increase, and there is a significant spatial correlation, but the absolute difference in CEP between cities increases. (2) GTF promotes the improvement of CEP in local cities. It reveals a favorable spillover impact on enhancing the neighboring cities' CEP. Furthermore, the research findings remain pertinent even after conducting rigorous tests to ensure their robustness. (3) Regional heterogeneity has been observed in the impact of GTF on CEP, with the development of GTF significantly contributing to the amelioration of CEP of neighboring cities in the east, significantly contributing to the improvement of local CEP of central cities and simultaneously contributing to the improvement of local and neighboring cities' CEP in the west. (4) The findings of the intermediary examination show that GTF mainly promotes CEP through the positive incentive effect of promoting green innovation in technology and the reverse push-back effect of optimizing the structure of industries. (5) The spatial spillover effect of GTF on CEP is more sensitive under the geographic distance matrix, showing a "three-stage" decay characteristic from near to far, and its influence range is roughly 300km. Therefore, China should strengthen the development of GTF, cross-city communication and cooperation to boost the accomplishment of the carbon neutrality objective.

The ecological accountability reform and corporate investment efficiency: Evidence from a policy shock

The ecological accountability reform is an emerging environmental regulatory tool used by transition economies to correct failures and deviations in the traditional central-local environmental governance mode. This paper applies the propensity score matching with difference-in-differences method to test the impact of the central environmental inspection, an ecological accountability mechanism, on the investment efficiency of enterprises. The results reveal that the central environmental inspection can improve the corporate investment efficiency by resisting the urge to over-investment. Furthermore, this policy can improve corporate investment efficiency by dual functions of the incentive effect of increasing R&D investment and the pushback effect of financial risk. After a series of robustness checks, the results remained reliable. Heterogeneity tests show that the effect gradually appears in regions that implemented policy lately or with re-inspection, indicating the necessity of establishing a long-term mechanism. What's more, the positive effect of the central environmental inspection on corporate investment efficiency will be more significant in SOEs, large companies, and companies in provinces with weak environmental regulations. To achieve carbon peaking and carbon neutrality goals, this paper provides implications for improving collaborative governance system of local environmental protection and strengthening the linkage of environmental regulation and enterprise investment.

Comparative study of the micro-mechanism of charge redistribution at metal-semiconductor and semimetal-semiconductor interfaces: Pt(Ni)-MoS2 and Bi-MoS2(WSe2) as the prototype

The generation of Schottky barrier height (SBH) at the metal–semiconductor junctions (MSJ)is a hot topic in the area of new two-dimensional (2D) semiconductors. As the charge distribution theory is an effective approach to study the generation of SBHs at the interface, and it has not been studied in depth so far. In this paper, two groups of metal–semiconductor (Pt-MoS2 and Ni-MoS2) and semimetal-semiconductor (Bi-MoS2 and Bi-WSe2) structures are designed, and their charge redistribution mechanisms are studied by the first-principles density functional theory (DFT). The result shows that the band gaps at the interfaces of Pt-MoS2 and Ni-MoS2 are 0.73 eV and 0.68 eV, respectively, and a large SBH is appeared, while the band gaps at the interface of Bi-MoS2 and Bi-WSe2 are basically not exist. The large SBHs are produced at metal–semiconductor (M−S) interfaces due to the push-back effect and metal-induced gap states (MIGS). The weak orbitals and special density of states (DOS) (near-zero DOS at the Fermi level) of Bi atoms at the semimetal-semiconductor (S-S) interface can avoid orbital hybridization and fill the band gap, thus an Ohmic Contact is formed. Additionally, stress modulation is also performed for both sets of interfaces, and the comparison shows that M−S interface is more sensitive to stress modulation than the S-S interface, and the stress has the most pronounced effect on the interface dipole (ΔV), especially at the M−S interfaces. These calculations provide a theoretical complement to the mechanism of ultra-low contact resistance formation at MSJ, bringing new theory and insight into the development of two-dimensional semiconductor devices.

How can we make an orderly transition away from fossil fuels? A global tour of modern energy

This paper analyzes the economic, social and political three-dimensional driving effects of new energy substitution for fossil energy under the joint action of market, government and international competition from three perspectives: profit motive, mutual benefit and responsibility motive, combined with the relevant data of 78 countries from 1965 to 2021. The results show that fossil energy prices and energy security positively influence the process of new energy substitution, and environmental pollution negatively affects the process of new energy substitution, and the pushback effect of energy security on new energy substitution is more significant in the study interval, indicating that at the beginning of the new energy revolution, global environmental governance and willingness to reduce emissions drive the development of new energy industry, but the “carbon emission reduction” of each country has increased the complexity of new energy substitution, especially in some developed countries in taking responsibility for global environmental governance divergent views. Further heterogeneity analysis reveals that each country’s energy strategy affects the degree of substitution of “quality” and “quantity” of new energy, and the speed, areas and corrective ability of new energy development vary among countries under different strategic choices.

Coverage-Dependent Modulation of Charge Density at the Interface between Ag(001) and Ruthenium Phthalocyanine

When an organic film is deposited on a metal surface, charge layers are formed at the interface. These are an important feature of the interface electronic structure and play a crucial role as separation layers between electrodes and active layers in organic devices. Here, we report on a study of the interface between diruthenium phthalocyanine, (RuPc)2, and the Ag(001) surface. The molecules form two different commensurable arrangements on the substrate, a low density one for a coverage well below the first monolayer and a high density one up to the completion of the monolayer. The focus of this study is on the interface states evolution with the molecular density on the metal surface and the charge distribution in the thin interfacial layer between molecules and substrate. From this investigation, conducted by low energy electron diffraction, scanning tunneling microscopy/spectroscopy, photoemission spectroscopy, and density functional theory, we have found that, even if individual molecules are characterized by a quite similar surface-to-molecule charge transfer pattern, the two molecular arrangements present different valence band structures and, more interestingly, different modulations of the interface charge. These charge modulations are governed by interfacial states energetically resonant with the molecular states, localized at the position of the molecules as well as by a reaction of the electronic cloud of the metal surface to the molecular adsorption due to a Pauli pushback effect. This complex, spatial charge modulation makes the (RuPc)2/Ag(001) an interesting case of interaction intermediate between physisorption and chemisorption.

Non-charge-transfer Origin of Tc Enhancement in a Surface Superconductor Si(111)-(\(\sqrt{7} \times \sqrt{3} \))-In with Adsorbed Organic Molecules

The effects of adsorption of Zn-phthalocyanine (ZnPc) molecules on the superconductivity of the Si(111)-(root7xroot3)-In surface are studied through transport measurements under ultrahigh vacuum environment. The ZnPc molecules are found to increase the transition temperature Tc by 11% at maximum, which is about 2.7 times the Tc increase previously reported using CuPc. By contrast, angle-resolved photoemission spectroscopy measurements and ab initio calculations show that charge transfer from the In atomic layers to ZnPc is substantially smaller than that to CuPc. This clearly shows that charge transfer should be excluded as the origin of the increase in Tc. The push-back effect induced by physical adsorption of molecules is discussed as a possible mechanism for the Tc enhancement.

Resolution of Intramolecular Dipoles and a Push-Back Effect of Individual Molecules on a Metal Surface

Molecules consisting of a donor and an acceptor moiety can exhibit large intrinsic dipole moments. Upon deposition on a metal surface, the dipole may be effectively screened and the charge distribution altered due to hybridization with substrate electronic states. Here, we deposit ethyl-diaminodicyanoquinone molecules, which exhibit a large dipole moment in the gas phase, on a Au(111) surface. Employing a combination of scanning tunneling microscopy and noncontact atomic force microscopy, we find that a significant dipole moment persists in the flat-lying molecules. Density functional theory calculations reveal that the dipole moment is even increased on the metal substrate as compared to the gas phase. We also show that the local contact potential across the molecular islands is decreased by several tens of meV with respect to the bare metal. We explain this by the induced charge-density redistribution due to the adsorbed molecules, which confine the substrate’s wavefunction at the interface. Our local measurements provide direct evidence of this so-called push-back or cushion effect at the scale of individual molecules.

Microscopic EDL structures and charge-potential relation on stepped platinum surface: Insights from the ab initio molecular dynamics simulations.

The microstructural features and charge-potential relation of an electric double layer (EDL) at a stepped Pt(553)/water interface are investigated using ab initio molecular dynamics simulation. The results indicate that the chemisorbed O-down water molecules gather at the (110) step sites, while the (111) terrace sites are covered by the H-down water molecules, which greatly weakens the push-back effect of interface water on the spillover electrons of the stepped surface and, therefore, results in a much more positive potential of zero charge (PZC) than the extended low-index Pt surfaces. It is further revealed that around the PZC, the change in the surface charge density is dominated by the change in the coverage of chemisorbed water molecules, while EDL charging is the main cause of the change in the surface charge density at potential away from the PZC, thus leading to an S-shaped charge-potential relation and a maximum interface capacitance around PZC. Our results make up for the current lack of the atomic-scale understanding of the EDL microstructures and charge-potential relation on the real electrode surfaces with plentiful step and defect sites.

Hexacene on Cu(110) and Ag(110): Influence of the Substrate on Molecular Orientation and Interfacial Charge Transfer.

Hexacene, composed of six linearly fused benzene rings, is an organic semiconductor material with superior electronic properties. The fundamental understanding of the electronic and chemical properties is prerequisite to any possible application in devices. We investigate the orientation and interface properties of highly ordered hexacene monolayers on Ag(110) and Cu(110) with X-ray photoemission spectroscopy (XPS), photoemission orbital tomography (POT), X-ray absorption spectroscopy (XAS), low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and density functional theory (DFT). We find pronounced differences in the structural arrangement of the molecules and the electronic properties at the metal/organic interfaces for the two substrates. While on Cu(110) the molecules adsorb with their long molecular axis parallel to the high symmetry substrate direction, on Ag(110), hexacene adsorbs in an azimuthally slightly rotated geometry with respect to the metal rows of the substrate. In both cases, molecular planes are oriented parallel to the substrate. A pronounced charge transfer from both substrates to different molecular states affects the effective charge of different C atoms of the molecule. Through analysis of experimental and theoretical data, we found out that on Ag(110) the LUMO of the molecule is occupied through charge transfer from the metal, whereas on Cu(110) even the LUMO+1 receives a charge. Interface dipoles are determined to a large extent by the push-back effect, which are also found to differ significantly between 6A/Ag(110) and 6A/Cu(110).

Bias in the eye of beholder? 25 years of election monitoring in Europe

ABSTRACT Building on the original corpus of OSCE monitoring reports, the article analyses quarter of century of election monitoring in Europe and assesses the congruence of OSCE written assessments with expert views. We show that, overall, the OSCE monitoring reports are highly correlated and congruent with expert assessments. More importantly, the level of congruence between the two increases with time. However, we also identify various forms of biases rooted in strategic interests and institutional preconditions. Mainly, we show that OSCE has a strong and positive bias towards Russia and its allies when it comes to election assessments indicating defensive and lenient stances. We theorize this mechanism as a pushback effect and show that although Russia’s effort to cripple the activities of OSCE in the past two decades was not successful, OSCE was effectively forced into a defensive position producing less critical assessments than reality warrants.

Mechanism of charge redistribution at the metal-semiconductor and semiconductor-semiconductor interfaces of metal-bilayer MoS2 junctions.

Layer-number-dependent performance of metal-semiconductor junctions (MSJs) with multilayered two-dimensional (2D) semiconductors has attracted increasing attention for their potential in ultrathin electronics and optoelectronics. However, the mechanism of the interaction and the resulting charge transfer/redistribution at the two kinds of interfaces in MSJ with multilayered 2D semiconductors, namely, the metal-semiconductor (M-S) and the semiconductor-semiconductor (S-S) interfaces, have not been well understood until now, although that is important for the overall Schottky barrier height and the energy-band-offset between different layers of the 2D semiconductors. Here, based on state-of-the-art density functional theory calculations, the mechanisms of bonding and asymmetric electron redistribution at the M-S and S-S interfaces of metal-bilayer MoS2 junctions are revealed. Multiple mechanisms collectively contribute to the electron redistribution at the two kinds of interfaces, and the dominant mechanism depends on both the dimensionality (2D vs 3D) and the work function of metal electrodes. For the M-S interface, the pushback effect and metal-induced gap states play a dominant role for MSJs with 3D metal, while the covalent-like quasi-bonding feature appears for MSJs with medium-work-function 2D metals, and charge transfer plays a main role for MSJs with 2D metals that have very large or small work functions. For the S-S interface, it inherits the electron-redistribution behavior of the M-S interface for MSJs with 2D metal, while opposite electron-redistribution appears in MSJs with 3D metal. These mechanisms provide general insights and new concepts to better understand and use MSJs with multilayered 2D semiconductors.

Vacuum-Level Shift at Al/LiF/Alq3 Interfaces: A First-Principles Study.

Work function changes, or vacuum-level shifts (ΔVLS), in Al(001) surfaces by the adsorption of thin layers composed of tris(8-hydroxyquinolinato)aluminum (Alq3) and/or LiF are theoretically investigated. First-principles calculations reasonably reproduce experimentally obtained ΔVLS values, enabling us to discuss the underlying mechanism. Dipole moment of Alq3 and interfacial charge rearrangement (Pauli push-back effect) are the main reasons for ΔVLS at Al(001)–Alq3 and Al(001)–LiF interfaces, respectively. For a stacked Al(001)–LiF–Alq3 layer configuration, theory suggests a more complicated picture, which takes charge rearrangement between LiF and Alq3 layers into account, than a simple sum rule of dipole contributions from the two layers.

Electronic structure evolution at DBBA/Au(111) interface W/O Bismuth insertion layer

Atomically precise graphene nanoribbons (GNRs) can be on-surface synthesized from halogen containing molecular precursors. Here, we investigated the electronic structure evolution of 10,10′-dibromo-9,9′-bianthracene (DBBA), a famous precursor to 7-AGNRs, on both Au(111) and Bi-3×3-Au(111) as a function of film thickness and post-annealing temperature using photoemission spectroscopy, low temperature scanning tunneling microscopy and density functional theories. No obvious changes in electronic structure of DBBA in three STM-observed configurations can be detected, indicating that nonplanar π -conjugated DBBA is physisorbed on both surfaces. The energy level alignments at the DBBA-substrate interfaces are demonstrated. Bismuth(Bi) insertion layer makes molecular−substrate interaction weaker, and makes the energy levels of DBBA thin film rigidly shift by ˜0.70 eV away from Fermi level, which enlarges the hole injection barrier and results in DBBA desorption at ˜470 K before dehalogenation occuring. The surface work function reduction can be explained by the push back effect and charge transfer induced interface dipole. Our findings explain why 7-GNRs could not be formed on Bi-3×3-Au(111).

How adsorbates alter the metallic behavior of quasi-1D electron systems of the Si(5 5 3)-Au surface

The plasmonic signals of quasi-1D electron systems are a clear and direct measure of their metallic behavior. Due to the finite size of such systems in reality, plasmonic signals from a gold-induced superstructure on Si(5 5 3) can be studied with infrared spectroscopy. The infrared spectroscopic features have turned out to be extremely sensitive to adsorbates. Even without geometrical changes of the surface superstructure, the effects of doping, of the adsorbate induced electronic surface scattering, and of the electronic polarizability changes on top of the substrate surface give rise to measurable changes of the plasmonic signal. Especially strong changes of the plasmonic signal have been observed for gold, oxygen, and hydrogen exposure. The plasmonic resonance gradually disappears under these exposures, indicating the transion to an insulating behavior, which is in accordance with published results obtained from other experimental methods. For C70 and, as shown here for the first time, TAPP-Br, the plasmonic signal almost retains its original intensity even up to coverages of many monolayers. For C70, the changes of the spectral shape, e.g. of electronic damping and of the resonance position, were also found to be marginal. On the other hand, TAPP-Br adsorption shifts the plasmonic resonance to higher frequencies and strongly increases the electronic damping. Given the dispersion relation for plasmonic resonances of 1D electron systems, the findings for TAPP-Br indicate a push-back effect and therefore stronger confinement of the free charge carriers in the quasi-one-dimensonal channel due to the coverage by the flat TAPP-Br molecules. On the gold-doped Si(5 5 3)-Au surface TAPP-Br acts as counter dopant and increases the plasmonic signal.

Electronic properties of hybrid organic/inorganic semiconductor pn-junctions

Hybrid inorganic/organic semiconductor heterojunctions are candidates to expand the scope of purely organic or inorganic junctions in electronic and optoelectronic devices. Comprehensive understanding of bulk and interface doping on the junction’s electronic properties is therefore desirable. In this work, we elucidate the energy level alignment and its mechanisms at a prototypical hybrid pn-junction comprising ZnO (n-type) and p-doped N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (α-NPD) as semiconductors, using photoelectron spectroscopy. The level alignment can be quantitatively described by the interplay of contact-induced band and energy level bending in the inorganic and organic component away from the interface, and an interface dipole due to the push-back effect. By adjusting the dopant concentration in α-NPD, the position of the frontier energy levels of ZnO can be varied by over 0.5 eV and that of α-NPD by over 1 eV. The tunability of this pn-junction’s energy levels evidences the substantial potential of the hybrid approach for enhancing device functionality.

Dependence of the adsorption height of graphenelike adsorbates on their dimensionality

Comparing the adsorption heights of various graphene nanoribbons on Cu(111) and Au(111) surfaces to those of graphene and $\ensuremath{\pi}$-conjugated planar organic molecules, we observe that two-dimensional graphene adsorbs much further away from the surface than both one-dimensional graphene nanoribbons and $\ensuremath{\pi}$-conjugated planar molecules---which represent zero-dimensional graphene flakes. We show that this is a direct consequence of the adsorbates' dimensionality. Our results provide invaluable insights into the interplay of Pauli repulsion, pushback effect, and chemical interaction for graphenelike adsorbates of any dimensionality on metal surfaces.