Initial Stages Of Transition Research Articles

First-principles molecular dynamics of exciton-driven initial stage of plasma phase transition in warm dense molecular nitrogen.

Understanding the properties of molecular nitrogen N2 at extreme conditions is the fundamental problem for atomistic theory and the important benchmark for the capabilities of first-principles molecular dynamics (FPMD) methods. In this work, we focus on the connection between the dynamics of ions and electronic excitations in warm dense N2. The restricted open-shell Kohn-Sham method gives us the possibility to reach relevant time and length scales for FPMD modeling of an isolated exciton dynamics in warm dense N2. Wannier localization sheds light on the corresponding mechanisms of covalent bond network rearrangements that stand behind polymerization kinetics. FPMD results suggest a concept of energy transfer from the thermal energy of ions into the internal energy of polymeric structures that form in warm dense N2 at extreme conditions. Our findings agree with the thermobaric conditions for the onset of absorption in the optical spectroscopy study of Jiang et al. [Nat. Commun. 9, 2624 (2018)].

Free Energy Evaluation of Cavity Formation in Metastable Liquid Based on Stochastic Thermodynamics.

Nucleation is a fundamental and general process at the initial stage of first-order phase transition. Although various models based on the classical nucleation theory (CNT) have been proposed to explain the energetics and kinetics of nucleation, detailed understanding at nanoscale is still required. Here, in view of the homogeneous bubble nucleation, we focus on cavity formation, in which evaluation of the size dependence of free energy change is the key issue. We propose the application of a formula in stochastic thermodynamics, the Jarzynski equality, for data analysis of molecular dynamics (MD) simulation to evaluate the free energy of cavity formation. As a test case, we performed a series of MD simulations with a Lennard-Jones (LJ) fluid system. By applying an external spherical force field to equilibrated LJ liquid, we evaluated the free energy change during cavity growth as the Jarzynski's ensemble average of required works. A fairly smooth free energy curve was obtained as a function of bubble radius in metastable liquid of mildly negative pressure conditions.

Effect Mechanism of α-Ferrite Sustained Precipitation on High-Temperature Properties in Continuous Casting for Peritectic Steel

Exploring the mechanism of the α-ferrite precipitation process on high-temperature properties plays an important guiding role in avoiding slab cracks and effectively regulating quality. In this work, in situ observation of the α-ferrite sustained precipitation behavior for peritectic steel during the austenitic phase transition process has been investigated using high-temperature confocal scanning laser microscopy. Meanwhile, the high-temperature evolution of the phase fractions during the phase transition process was quantitatively analyzed based on the high-temperature expansion experiment using the peak separation method. Furthermore, the high-temperature properties variations of the casting slab during the α-ferrite sustained precipitation process were investigated with the Gleeble thermomechanical simulator. The results show that the film-like ferrite precipitated along the austenite grain boundaries at the initial stage of phase transition, then needle-like ferrite initiates rapid precipitation on film-like ferrite when the average thickness reaches 15~20 μm. Hot ductility reached a minimum at the ferrite phase fraction fα = 10~15%, while high-temperature properties returned to a higher level after fα > 40~45%. The appearance of a considerable amount of needle-like ferrite and grain refinement effectively improves the high-temperature properties with the α-ferrite precipitation process advances.

Experimental study on boundary layer of internal flow visible supersonic nozzle

The high-frequency pulsation noise generated by the turbulent boundary layer on the wall of a Laval nozzle can significantly affect the quality of the flow field at the nozzle outlet. In this study, a supersonic wind tunnel with visible internal flow is designed and fabricated to observe the development and evolution of the boundary layer on the contraction and expansion surfaces of a Laval nozzle, as well as to study the flow field inside the supersonic nozzle. The subsonic, transonic and supersonic profiles of the nozzle are designed by bicubic curve, Hall method and classical characteristic line method respectively. The results of numerical calculation and total pressure measurement show that the flow field at the nozzle outlet of the wind tunnel is uniform and stable, and the deviation of Mach-number-root mean square is better than the qualified level of China's national military standard. Nanoparticle-tracer based planar laser scattering (NPLS) technology is used to carry out the flow display test of the internal flow visual supersonic nozzle, and the fine structure image of the whole flow field in the nozzle is obtained. The image clearly shows the development and evolution of the boundary layer in the nozzle. The interface between boundary layer and main stream and the wall curve of nozzle transition region are extracted by image processing technology. The fractal dimension of the extracted boundary layer contour is calculated, thereby establishing the corresponding relationship between the fractal dimension and the boundary layer state, and determining the transition position of the boundary layer. The results show that the transition position of the nozzle profile is closer to downstream than that of the nozzle straight wall. The fractal dimension can qualitatively judge the flow state of the boundary layer; however, it is necessary to distinguish between laminar boundary layers and hairpin vortices in the initial transition stage by considering the thickness of boundary layer.

PROBLEMS AND TRENDS OF UKRAINE'S TRANSITION TO THE EU ENVIRONMENTAL AND ENERGY SYSTEM

The article is devoted to the problems and trends of the transition to the ecological and energy system of the EU countries and Ukraine. It examines the essence and necessity of such a transition, as well as the transition levels at which countries are located and the corresponding energy clusters. The purpose of the scientific research is to analyse the levels of the energy transition of the countries of the European Union, to identify the problems and trends of their development, as well as to propose possible ways to further improve the energy policy of Ukraine in order to achieve environmental sustainability and energy security. The study found that the transition to an ecological and energy system is necessary to ensure sustainable development and reduce the impact on the environment. It is indicated that the EU countries are already making the ransition to a new energy system with low carbon emissions, and are also actively using renewable energy. At the same time, Ukraine is at the initial stage of transition and has significant potential for the development of renewable energy and energy efficiency. At the same time, the problem of such a transition was identified, namely, excessive overloading of electricity consumers with tax pressure, which leads to a low level of consumption per capita. In addition, clusters of countries that are at different levels of transition to an ecological and energy system were identified. These clusters take into account the level of development of renewable energy and energy efficiency. The definition of these clusters can help countries in the development and implementation of national energy policies.

Profil Gerak Dasar Manipulatif Melempar Siswa di Sekolah Menengah Pertama

This study analyzes throwing in the basic manupulatif movements of junior high school students in the Bandung city environment. The research method used by researchers uses descriptive research methods with a quantitative approach. The sample in this study was 23 class IX students aged 15-16 years. The data collection used in this study was using a research instrument in the form of observation sheets based on a book by David L Gallahue entitled Developmental Physical Education for Today's Children. These students are likelier to do all the fundamental movement skills given in the early and transitional stages. The results obtained from basic manupulatif movements in the form of throwing motion skills are divided into three groups, including the initial stage (10.62%), transitional stage (5.31%), and mature stage (0%). In conclusion, the results of the study obtained an overview of the various kinds of abilities possessed by students in carrying out various basic manupulatif movements with throwing motion skills.
 Keywords : Basic manupulatif movements, physical activity, and the COVID-19 pandemic

Innovative library practices in the context of industry modernization: Experience of historical analysis

The main directions of modernization of library business and development of innovative activity of libraries under the influence of this process in the 90s and the decades following them are considered. The relationship of these basic vectors of development of the industry has not actually been the subject of special consideration. The article is an experience of system analysis of innovative practices of Russian libraries in the context of modernization as a global process of transformation of social development. The concept of "modernization of librarianship" is defined as a complex process that includes not only the computerization of the industry, but also its socio-cultural, institutional, managerial, functional and organizational transformations. The features of the initial stage of transition of domestic libraries to the path of modernization are characterized. It is noted that in accordance with the General trends of modernization, the domestic library business at the turn of the Millennium moved from linear progress, i. e. extensive development path to intensive, providing for qualitative transformations of the industry. The article presents external and internal modernization factors that influenced the innovative changes in the industry. The main trends in the development of library innovations are highlighted, which have enriched the implementation of the basic social functions of libraries in terms of content and technology: information, memorial, educational, cultural and educational, social and communicative. The article highlights the main trends in the development of innovations that affected the basic social functions of libraries: information, memorial, educational, cultural and educational, social and communicative. The article analyzes the socio-targets, tools and content of functional transformations of libraries. It is concluded that modernization, as the general vector of the development of the industry, is the main stimulus for library innovations, which, in turn, are its practical implementation in the processes of functioning of libraries.

Applied Aspects of Progressive Taxation of Personal Income

In 2018 and 2019, the author published a number of articles on progressive taxation of personal income. The concept of fair taxation, formulated using the utility function, was introduced and put into mathematical form, illustrative examples of such taxation were built. In this article, this topic is updated, but with an emphasis on the possible practical use of the results obtained. All calculations were carried out on the basis of a detailed distribution of taxable income by groups of taxpayers, built on the reporting data of 2020. This made it possible to compare the results obtained with the real taxation of personal income. Specific variants of the progressive tax function were built and analyzed, providing a reduction in tax payments for 90% of taxpayers with low incomes, subject to the condition of acceptability of tax rates applied to high and ultra-high incomes. An important conclusion was made about the possibility of applying a specific five-step scale of tax rates at the initial stage of transition to progressive taxation of personal income.

Wheel/rail adhesion and damage under different contact conditions and application parameters of friction modifier

Friction modifier (FM) is a newly developed third medium to control the service performance of wheel/rail. The wheel/rail performance is influenced by the wheel/rail contact conditions and FM application parameters. Therefore, the effects of FM application parameter and the wheel/rail contact parameters on the adhesion and damage behaviors of wheel and rail materials should be explored. In this study, the influences of application amount of FM, the wheel/rail contact stress and the creepage on the adhesion and damage behaviors were studied using a twin-disc machine. Results indicated that the increase in contact stress would reduce the wheel/rail minimum adhesion coefficient and effective holding time of FM. The increase in the creepage would increase the adhesion coefficient and reduce the holding time. Under the wheel/rail contact stresses of 800 and 1100 MPa, the application of FM could reduce wheel/rail wear and damage. But under 1500 MPa, FM could cause serious rail surface damages. Moreover, the surface crack propagation process of rail mainly included three stages: initial stage, transition stage and rapid propagation stage. The “oil wedge effect” was the main mechanism for aggravating the surface damages of rail under 1500 MPa.

Engineering Morphology and Ni Substitution of NixCo3–xO4 Spinel Oxides to Promote Catalytic Combustion of Ethane: Elucidating the Influence of Oxygen Defects

Transition metal oxides are potential alternatives to noble metal catalysts for oxidation reactions. Co-based spinel oxides, in particular, have attracted significant attention. Herein, NixCo3–xO4 catalysts were synthesized to elucidate the influence of oxygen vacancies on catalyst activities and reaction mechanisms for ethane combustion. A correlation between the activity and the population and properties of O defects was developed, with an increased number of O defects typically resulting in higher activity. Also, the shape-induced facet effect is related to the amount of Ni that is incorporated into the octahedral sites of Co oxide. The substituted Ni atoms altered the redox ability of NixCo3–xO4 by changing O vacancy formation and C–H bond dissociation. The NiCo2O4-TM catalyst (6.0 mmol mL–1 h–1) exhibits the highest activity for ethane oxidation compared with NiCo2O4-PC (0.5 mmol mL–1 h–1) and NiCo2O4-OL catalysts (1.3 mmol mL–1 h–1) at 330 °C, and its activation energy (Ea) is 70.9 kJ mol–1. No activity decay is observed after the initial transition stage of the reaction in a long-term stability test up to 500 h on the NiCo2O4-TM-coated monolith, either with or without water addition. A vacancy-mediated pathway was proposed according to in situ diffuse reflectance infrared Fourier transform (DRIFT) and density functional theory (DFT) calculations over the NiCo2O4(311) facet. Findings from this study expand our understanding of the facet-dependent catalytic behavior and ultimately enable the rational design of high-performance catalysts.

Разработка региональных государственных программ поддержки сельхозтоваропроизводителей, внедряющих углеродно-нейтральные технологии

The article presents an analysis of research on state support for agricultural producers implementing carbon-neutral technologies, which allowed us to assess the range and effectiveness of tools for this support in the agro-industrial complex of Russia. The relevance of the development of regional programs in accordance with the requirements of the importing countries of our agricultural products is proved. The increase in costs at the initial stage of energy transition should help to implement technological sovereignty projects that provide for the sustainable production of high-tech products of a full innovation cycle based on domestic developments, including carbon-neutral technologies. These costs should be compensated by various instruments of state support (subsidies, preferential loans, preferential taxation, access to resources, innovation). The developers of the state policy of low-carbon regulation in Russia should, using international practice, raise and solve the following questions: what are the incentives for the introduction of low-carbon projects for business and the public, whether the existing set of state support tools is sufficient, how the indicators of the state low-carbon policy are compared with market identifiers associated with the energy transition to a decarbonized economy. The conducted research suggests that the instruments of state support for low–carbon projects in the sectors of the Russian economy, including subsidies for the modernization of existing production facilities, the introduction of the best technologies with low and zero greenhouse gas emissions, tax incentives, should be worked out at the level of regions or macro-regions - federal districts, using foreign experience.

Performance appraisal practices in Bangladesh: the role of culture

Although existing human resource management literature has investigated the link between performance appraisal and culture, research based on smaller economies in Asia is limited. With a multiple case study approach, this paper analysed the performance appraisal process of five organisations in the private sectors of Bangladesh. It also examined how cultural dimensions, namely, assertiveness, in-group collectivism, power distance, uncertainty avoidance and future orientation, influence the appraisal practices. The findings show that pioneer domestic firms are in the initial stage of transition to performance management from performance appraisal, while weaknesses, such as single-source rating, a lack of performance feedback, and an absence of documentation for performance monitoring, exist in general. In addition, recent changes in employee assessment systems reflect shifts in the national culture. This study contributes to the literature that combines performance appraisal and culture, especially in the context of an emerging economy. It also offers managerial and policy implications.

Discovering the sluggishness of triathlon running - using the attractor method to quantify the impact of the bike-run transition.

Running in a triathlon, a so-called brick run, is uniquely influenced by accumulated load from its preceding disciplines. Crucially, however, and irrespective of race type, the demands of a triathlon always exceed the sum of its parts. Triathletes of all levels commonly report subjectively perceived incoordination within the initial stages of the cycle run transition (T2). Although minimizing it, and its influence on running kinematics, can positively impact running and overall triathlon performance, the mechanisms behind the T2 effect remain unclear. In the present study, we assessed the influence of the pre-load exercise mode focusing on the biomechanical perspective. To analyze inertial sensor-based raw data from both legs, the so-called Attractor Method was applied. The latter represents a sensitive approach, allowing to quantify subtle changes of cyclic motions to uncover the transient effect, a potentially detrimental transient phase at the beginning of a run. The purpose was to analyze the impact of a pre-load on the biomechanics of a brick run during a simulated Olympic Distance triathlon (without the swimming section). Therefore, we assessed the influence of pre-load exercise mode on running pattern (δM) and precision (δD), and on the length of the transient effect (tT) within a 10 km field-based run in 22 well-trained triathletes. We found that δD, but not δM, differed significantly between an isolated run (IRun) and when it was preceded by a 40 km cycle (TRun) or an energetically matched run (RRun). The average distance ran until overcoming the transient phase (tT) was 679 m for TRun, 450 m for RRun, and 29 4 m for IRun. The results demonstrated that especially the first kilometer of a triathlon run is prone to an uncoordinated running sensation, which is also commonly reported by athletes. That is, i) the T2 effect appeared more linked to variability in running style than to running style per se ii) run tT distance was influenced by preceding exercise load mode, being greater for a TRun than for the RRun condition, and iii) the Attractor Method seemed to be a potentially promising method of sensitively monitoring T2 adaptation under ecologically valid conditions.

“Turbulent/non-turbulent interface” in a low-Reynolds-number transitional boundary layer over a multi-element airfoil

Akin to the turbulent/non-turbulent interface, which envelops a fully developed turbulence, the iso-vorticity interface that separates the irrotational fluids from the free stream is investigated in a transitional boundary layer over a multi-element airfoil. Geometrically, the interface is steady and flat at the initial transitional stage. With the progress of transition, the interface fluctuates more and more violently. Statistically, the evolution of interface properties, including the fluctuation of interface height σI, the fractal dimension Df, and the thickness of interface δI, are tracked along the streamwise direction. It is revealed that all the three quantities grow with transition. Both σI and δI become invariant at the latter half part of the airfoil where the transition is completed. Counter-intuitively, the growth of Df stops at a more upstream location, indicating the fractal property of turbulence is already existing during transition. Instantaneously, the above-mentioned quantities are found to be related to the periodical vortices inside the boundary layer. The vortex will elevate/sink the above interface by the induced ejection/sweep flow and increases Df at slightly downstream of the vortex. Furthermore, it is highlighted that the variations of interface properties will greatly influence the entrainment by two opposite effects: the length of interface LI and the vorticity gradient across the interface; and it is found that the entrainment flux is mainly controlled by LI. This suggests that the recently reported dominance of LI on entrainment for wall-bounded turbulence could be a universal phenomenon in boundary layers, despite the flow states and wall configurations.

The development of deformation mechanism during tension at different strain rates for GH4169 superalloys quantified by in-situ acoustic emission

The effect of strain rate on deformation has been an important issue involving material processing and service performance, where, however, the underlying mechanism is still an open question. Especially, the quantitative understanding of mechanism development during the deformation process remains unclear. In the present work, in-situ acoustic emission (AE) measurement has been performed on GH4169 superalloys at different strain rates ranging from 3.3 × 10−5 s−1 to 3.3 × 10−3 s−1, where a quantitative investigation on mechanism development during tension is achieved. The adaptive sequential k-means (ASK) algorithm has been used to extract deformation mechanisms from the AE signals. The main results show that the precipitates shearing and the slip bands are the dominating AE sources during the deformation process, which has been firmly supported by the ex-situ observation on microstructures. Furthermore, the average level of AE energy decreases with the strain rate, which suggests that the density of mobile dislocations is lower and the width of the slip band is narrower when superalloys are deformed at a relatively higher strain rate. The high-energy AE events are concentrated in the initial transitional stage with the appearance of a peak, which, however, decrease with the strain rate in the linear hardening stage. Meanwhile, the cumulative AE energy and AE number contributed from the precipitates shearing are predominant as compared with those from the slip bands, which gives a hint that the precipitates shearing plays the principal role in the deformation process. However, when the strain rate is relatively high, the effect of the slip bands becomes more significant, which leads to deteriorative ductility. Those findings might provide some insight into the deformation, strengthening and failure mechanisms for nickel-based superalloys.

Exploring the influencing factors of carbon neutralization in Chinese manufacturing enterprises.

One of the key issues facing the government in achieving carbon neutrality is what methods can be used to effectively reduce carbon emissions. Taking manufacturing enterprises as an example, this paper studies the carbon emission reduction effects of green technology innovation subsidy (GIS), carbon tax (CT), and carbon emission trading (CET). Under the background of social welfare and carbon emission reduction efficiency, we get the results of optimal carbon emission reduction measures in different environments. The results are as follows: (1) In the initial and mature stage of green technology innovation, GIS is the best choice to improve the degree of green manufacturing and maximize social welfare. CT and CET are the best choice to obtain the highest SE (carbon emission reduction efficiency). (2) In the transitional stage, CET and CT can promote the maturity of green technology. However, with the maturity of green technology, the promotion of green technology has weakened. CT is the best choice to achieve the highest SE. (3) When the carbon tax or carbon trading price is at a high or low level, raising the tax rate or carbon trading price can increase the income of enterprises. Therefore, the government should take measures according to the objectives of different stages. When the goal is to maximize social benefits, GIS is the best choice in the initial stage and transition stage, and CET or CT is the best choice in the transition stage. In the initial stage and fertilization stage, when the highest SE, CT, or CET is the best choice, while in the transition stage, CT is the best choice.

Models of deforestation for setting reference levels in the context of REDD: A case study in the Peruvian Amazon

One of the main elements in the mechanisms proposed by REDD+ , is to pay countries (and then the users and/or forest owners, depending on each type of project), for real reductions in deforestation and the resulting GHG emissions, as well as to ensure other benefits, such as technical assistance and qualification, among others. To be able to estimate the emission reductions, it is necessary to establish a Reference Level either through different forms of a historical average or in the form of a BAU or “Business as Usual” scenario. In this sense, current proposals set the Reference Levels equal to historical deforestation, which apply another political logic to the predictions made by the Forest Transition (FT) theory. According to this theory, when using a simple historical extrapolation, it is possible that: “countries with a lot of forest and little deforestation”, lose in the initial stages of forest transition, while “countries with little forest and a lot of deforestation”, win in the later stages of the FT. Our study shows how the predictions of FT and other socio-economic variables can be incorporated into predictive models (historical trend), by including the forest area as an explanatory variable. Sub-national data from the 15 departments with forest cover in the Peruvian Amazon are used to develop 6 optional deforestation models for comparative purposes. It is observed that the most important predictive variable to explain current deforestation is historical deforestation. In the same way, it is observed that when applying and implementing econometric models with different variables, there are projections very close to the results of spatially explicit models for Peru (models that include spatial data for distance to roads, elevation, slope, distance to populated centers, among others). The variation of results is only 3–4%, so it can be concluded that the projections based on the historical trend considering the forest transition of each region and other socio-economic variables, are very good estimators of the deforestation expected in the future and are adequate to define the possible reductions by deforestation and degradation in the Peruvian Amazon or other areas with similar conditions.

Morphology, mating system and taxonomy of Volvox africanus (Volvocaceae, Chlorophyceae) from Thailand

BackgroundThe oogamous green algal genus Volvox exhibits extensive diversity in mating systems, including heterothallism and homothallism with unisexual (male and/or female) and/or bisexual spheroids. Although four mating systems have been recognized worldwide in strains identified as “Volvox africanus”, most of these strains are extinct. However, we previously rediscovered two types of the four mating systems (heterothallic, and homothallic with male and bisexual spheroids within a clone) from an ancient Japanese lake, Lake Biwa.ResultsHere, we obtained strains exhibiting the third mating system (homothallic with unisexual male and female spheroids within a clone) from a freshwater area of Kalasin Province, Thailand. When sexual reproduction was induced in the present Thai strains, both male and female unisexual spheroids developed to form smooth-walled zygotes within a clonal culture. Phylogenetic analyses of the internal transcribed spacer region-2 of nuclear ribosomal DNA sequences from all four mating systems, including the extinct strains, resolved the third mating system is basal or paraphyletic within the homothallic clade.ConclusionsThe present morphological and molecular data of the Thai strains indicate that they belong to the homothallic species V. africanus. The phylogenetic results suggested that third mating system (homothallic with separate male and female sexual spheroids) may represent an initial evolutionary stage of transition from heterothallism to homothallism within Volvox africanus. Further field collections in geologically stable intracontinental regions may be fruitful for studying diversity and taxonomy of the freshwater green algal genus Volvox.

Endemism and evolution of Podostemaceae in Phou Khao Khouay National Park, Lao PDR

Podostemaceae of the Phou Khao Khouay National Park and adjoining areas (PKK Area) in Lao PDR were recorded in separate papers, and scattered data make it difficult to gain the whole picture of their diversity and evolution. Our literature research enumerated 18 species and six genera, which account for 43% of species and 55% of genera indigenous to Laos, including 13 PKK Area-endemic species (72%) and three PKK Area-endemic genera (50%). The richness and endemism of species and genera of the PKK Area have the highest density in Asia. Most likely, the genera and all nine endemic species of Hydrobryum evolved in the PKK Area. Four endemic species of Hydrobryum are ribbon-like/subcylindrical-rooted and sympatric with foliose-rooted congeners. The evolutionary way is opposite to the early one in the ancestor of the Hydrobryum clade; the 2-way evolution, together with sympatry, is suggested to be non-adaptive. Two species are perhaps polyphyletic in the initial stage of phylogenetic-species transition. The characteristics of the Podostemaceae found in the PKK Area are important in the context of both biological science and conservation.

Natural Regeneration After Gold Mining in the Peruvian Amazon: Implications for Restoration of Tropical Forests

Context:Gold mining is the most destructive activity in the natural forests of the Madre de Dios region in the southeastern Peruvian Amazon. Understanding the natural regeneration process of these degraded areas is necessary to develop forest restoration projects in such conditions.Aims:We aimed to evaluate forest recovery and identify the successional and structure patterns of vegetation governing natural regeneration over time.Methods:Structure, composition, richness, diversity, and successional status were evaluated in abandoned artisanal gold mine areas in Madre de Dios, southeastern Peru. Vegetation data were recorded in 61 plots of 250 m2established in five sites varying from 1 to 19 years of abandonment. Vegetation in abandoned areas was compared with six undisturbed forests evaluated in previous inventories.Results:In the mining lands, tree density and basal area recovered quickly, while species richness and composition were slow. Forest recovery is an initial stage of transition from pioneer to early secondary species until at least 19 years after abandonment. The most abundant and frequent species were the fast-growing speciesOchroma pyramidaleandCecropia engleriana.These species could be considered potential candidates to promote restoration plans. Pioneer species represented 63% of the number of species in plots of 1–4 years, 57% in plots of 5–7 years, and 50% in plots of 8–19 years. Early and late secondary species represented 34 and 16%, respectively, of the number of species in plots of 8–19 years. Abandoned mining and reference plots present less than 5% of species in common.Conclusion:Our results highlight a slow natural regeneration process in areas for up to 19 years after gold mining. Species from different successional statuses were identified as potential candidates for recovering vegetation in such areas. Our findings may have important implications for further research focusing on the ecological restoration in tropical forests severely degraded by gold mining.