Boundary Dissolution Research Articles

The role of annealing and grain boundary controls on the mechanical properties of limestones and marbles

Chemical and mechanical processes are coupled in many geological and geochemical environments. Reactive processes anneal defects and restructure grain boundaries, modifying their elastic properties, levels of internal friction, wave propagation rates and fracture behaviors. The nature of these changes is, however, contingent on the initial state of the rock. In this study, impulse excitation was used to measure changes in mechanical properties as a function of dry and steam heating time at 300 °C for three carbonate rocks: Carrara marble, Carthage marble (Burlington Limestone), and Texas Cream limestone (Edwards limestone), with initial porosities of about 1 %, 3 %, and 27 %, respectively. Frequency-dependent phenomena along with mineral recrystallization were observed. This was coupled with small-angle X-ray and neutron scattering analysis to determine the relationship between changes in bulk mechanical and microstructural properties. An observed decrease in both the Young's and shear moduli in the experimental limestones as a function of heating time reflects and quantifies a reduction in the stiffness of the rock due to annealing. The internal friction of the samples first increases then decreases with reaction time, reflecting defect annealing, but this was balanced against grain boundary dissolution apparently driven by condensation of steam in the confined grain-boundary environment. This suggests an increase in the boiling point under confinement leading to dissolution, increased porosity and widening of the grain boundaries. In addition, comparison of small-angle X-ray and neutron scattering results suggests that it is inappropriate to assume that pores are empty for quantitative analysis of typical small-angle scattering samples.

Modeling and Parameter Optimization of Multi-Step Horizontal Salt Cavern Considering Heat Transfer for Energy Storage

Horizontal salt caverns represent a prime choice for energy storage within bedded salt formations. Constructing multi-step horizontal salt caverns involves intricate fluid and chemical dynamics, including salt boundary dissolution, cavern development, brine flow, heat transfer, and species transportation. In this paper, the influence of heat transfer and turbulent flow is considered in developing a 3D multi-physics coupled flow model for the construction of multi-step horizontal salt caverns. The feasibility and accuracy of the model are verified by comparisons with the field data of the Volgograd horizontal salt cavern. The effects of turbulent flow and heat transfer on the dissolution process are thoroughly analyzed. By analyzing the characteristics of the flow field, the brine concentration distribution, and cavern expansion, the results indicate a steady rise in cavity brine concentrations throughout the leaching phases, with the previously formed cavities continuing to enlarge during subsequent leaching stages, albeit at a diminishing rate of expansion. Furthermore, the results reveal that a larger injection flow rate results in a larger cavern volume, whereas higher injection concentrations result in smaller cavern volumes. While the step distance has a minimal impact on cavern volume, identifying the optimal step distance remains crucial. This analysis of construction parameters aims to provide valuable insights into the design and engineering practices involved in developing multi-step horizontal salt caverns for energy storage purposes.

High-throughput aqueous passivation behavior of thin-film vs. bulk multi-principal element alloys in sulfuric acid

Multi-principal element alloys have the potential to show excellent passivation behavior. However, the detailed compositional and crystal structure design of these alloys requires a high-throughput strategy. We used combinatorial thin-film libraries of single-phase (FeCoNi)1-x-yCrxAly alloys and compared their passivation behaviors to corresponding bulk alloys. Our results demonstrate that the detailed passivation behaviors of thin-films and bulk alloys are different which is related to both nanoscale porosity within the thin-films and grain boundary dissolution. Nevertheless, we found that comparisons made among suitably designed sets of thin-film alloys can be used to determine the best corrosion performing bulk alloy composition.

A new concept of inoculation by isomorphic refractory powders and its mechanism for grain refinement

Isomorphic Inoculation (ISI) is a novel grain refinement technique during solidification by the addition of metallic powders to the melt rather than ceramics. The powders are designed to grow epitaxially rather than to nucleate new solid, increasing theoretically the ratio between solidified grains and inoculants to 1:1. This technique circumvents the energy barrier problems related to heterogenous nucleation in traditional grain refinement techniques. In this manuscript, we show through a combination of numerical and experimental techniques that this ratio could be reached. This is achieved through novel experimental techniques to replicate the effects of the melt on the powders. A new CaF molten salt experiment was used to, for the first time, show the recrystallization/grain growth of Ti powders at high temperature. In parallel, we calibrated a model on our experimental conditions and used it to calculate the dissolution rate of the powders in the melt. The combined effects of grain growth, preferential grain boundary dissolution (increasing the number of powders) and bulk dissolution (decreasing the number of powders) act together, bringing the number of particles present during solidification near that of the number of solidified grains found in the sample ingots. The per particle efficiency of this method is far in excess of traditional inoculation methods and has the potential for wide applications, especially in systems such as TiAl used here where the heterogeneous particles remaining in the as-cast material are undesirable.

Parent-child boundary dissolution and children's psychological difficulties: A meta-analytic review.

Boundary dissolution has broadly been defined as the breakdown of boundaries and loss of psychological distinctiveness in the parent-child subsystem. Qualitative reviews have highlighted the developmental and clinical value of examining boundary dissolution as a multidimensional construct. Though prior work suggests patterns share minimal variance, research has yet to quantitatively synthesize the weighted effect of distinct patterns. The primary aim of this meta-analysis was to aggregate empirical research on associations between boundary dissolution patterns and children's internalizing and externalizing symptoms. Four patterns of boundary dissolution were identified across developmental, clinical, and family systems literatures: (a) enmeshment-entanglement and blurring of the intergenerational parent-child boundary through psychologically controlling and intrusive behaviors, (b) disorganization-chaotic parent-child boundary (e.g., inexplicable, contradictory behaviors, and responses) reflecting no coherent pattern of relating, (c) caregiving-child functions as a caregiver providing parents with instrumental and emotional support and guidance, and (d) coerciveness-child operates as a disciplinarian or authoritarian to intimidate and control parents. The meta-analysis reviewed 478 studies. Although each boundary dissolution pattern was associated with internalizing and externalizing symptoms, weighted effects across patterns significantly varied in magnitude. Regarding externalizing symptoms, the weighted effect of enmeshment was stronger relative to the weighted effect of caregiving. Turning to internalizing symptoms, the weighted effect of enmeshment was stronger than the weighted effect of caregiving and coerciveness. Additionally, the weighted effect of disorganization was stronger than the weighted effect of caregiving. The robustness of weighted effects depended on child, contextual, and methodological characteristics as well as time lag. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Supplemental Material for Parent–Child Boundary Dissolution and Children’s Psychological Difficulties: A Meta-Analytic Review

Supplemental Material for Parent–Child Boundary Dissolution and Children’s Psychological Difficulties: A Meta-Analytic Review

Ayahuasca ceremonies, relationality, and inner-outer transformations to sustainability. Evidence from Takiwasi Center in Peru

ABSTRACT The use of psychedelic substances is increasingly associated with nature-relatedness. We explore whether entheogenic uses of ayahuasca in settings co-produced between Indigenous and Western knowledges may also foster relationality and sustainability transformations across ontology, praxis, and epistemology. A survey with 74 English-speaking individuals who attended Amazonian healing ceremonies at the Takiwasi Center in Peru, along with 11 semi-structured interviews and a discussion circle revealed unexpected personal shifts towards relationality. Beyond the expected increase in nature-relatedness, participants also reported boundary dissolution and changes in their perceptions of self, leading them to experience nature and non-human beings as having spiritual or human-like agency. The blurring of perceived boundaries between themselves and nature also challenged the materialist ontologies in which they had been educated and socialized. In terms of both epistemologies and praxis, co-produced ayahuasca ceremonies enhanced relational thinking and embodiment of relationality. Inner-outer transformations ensued from the post-ceremonial integration of the ‘plant’s teachings’ into participants’ daily lives. We discuss our findings’ contributions to the emerging field of inner transformations and the relational turn in sustainability. Potential sustainability benefits of scaling plant-based ceremonies need to be measured against their impacts on the Amazon rainforest and its biocultures.

New insights into the dolomitization and dissolution mechanisms of dolomite-calcite (104)/(110) crystal boundary: An implication to geologic carbon sequestration process

Geologic carbon sequestration (GCS) is a promising strategy to reduce the harm of CO2 due to the rapidly increased fossil fuel combustion. Dolomitization and dissolution processes of deeply buried carbonate reservoirs significantly impact the potential of GCS. However, previous investigations mainly focus on the macroscopic batch experiments, the mechanisms at atomic level are still unclear especially for crystal boundary, but urgently required. Herein, the GCS potential and the effects of boundary dissolution on calcite and dolomite were investigated based on both analytical and simulation methods such as molecular dynamics simulation (MDS) and density functional theory (DFT) calculations, to deeply unveil the mechanisms of dolomitization and formation of intergranular secondary pores from the atomic perspective. The morphology results indicated that the dissolution of calcite and dolomite in carbonic acid solution started via the edges and corners. In addition, the simulated results showed that the carbon sequestration potential presented an order in dolomite (PMg50%) > PMg40% > PMg30% > PMg20% > PMg10% > calcite by dolomitization due to the reduced bulk volume but increased lattice stress. Furthermore, both electrons transfer and diffusion coefficients results suggested that the (104)/(110) boundary was preferentially dissolved as compared to the (104) and (110) planes, indicating that crystal boundary was beneficial to the formation of pores for the oil and gas storage, but harmful to the stability of long-term GCS. Therefore, this study, for the first time, provides new insights into uncovering the mechanisms of the GCS process in depth, from an atomic level focusing on the crystal boundary, thereby promoting the understand of the long-term evolution for both calcite and dolomite in deep reservoirs.

Liquid-sodium compatibility of plasma-sprayed Titania-Stabilized Zirconia, Lanthanum Zirconate, and Yttrium Aluminum Monoclinic coatings

Air plasma-sprayed (APS) ceramic coatings are being explored as chemical, environmental, electrical, and thermal barrier systems for components employed in sodium-cooled fast-spectrum nuclear reactors. The design and constructional requirements of several components demand the APS coatings be in continuous contact with the aggressive and corrosive liquid-sodium (coolant) environments. Conventional APS coatings were found to be susceptible to liquid-metal corrosion in high-temperature liquid-sodium environments. Towards this, three of the emerging thermal barrier ceramics such as Titania-Stabilized Zirconia (TiSZ), Lanthanum Zirconate (LZ), and Yttrium Aluminum Monoclinic (YAM), are investigated in the current work by exposing APS deposited ceramic coatings in liquid-sodium at 400 °C for 500 h and 1000 h. TiSZ coatings exhibited severe erosion of the topcoat and a complete degradation at the end of 1000 h due to grain boundary dissolution and the weakening of intersplat boundaries. LZ coatings showed partial failure due to the combined effects of erosion of the topcoat and spallation due to the formation of delamination cracks in the bulk of the topcoat. Except for some mild surface attacks, YAM coatings revealed erosion resistance, phase stability, chemical inertness, and structural integrity in liquid-sodium.

Electrochemical micro-couple mechanism based on Si and Mn segregations revealing the initiation of grain boundary dissolution for Q235 carbon steel

The purpose of this work was to reveal the initiation mechanism of grain boundary dissolution (GBD) for carbon steels in acidic electrolytes containing NO2–. For Q235 carbon steel in a HNO3-NaNO2 solution with pH 4, the electrochemical methods of potentiodynamic polarization and scanning Kelvin probe force microscope (SKPFM) were applied to explore electrochemical behavior, and the surface methods of scanning electron microscope (SEM), electron back-scatter diffraction (EBSD) and scanning tunneling microscope (STM) were applied to explore surface microstructure and composition. Q235 carbon steel presented the electrochemical behavior of activation-passivation-transpassivation in pH 4 HNO3-NaNO2 solution, GBD occurred on steel surface during anodic polarization. GBD initiation, which showed a selective characteristic, was found at the grain boundaries of relatively high Si and Mn contents (high Si-Mn grain boundary) when Q235 carbon steel was polarized to active–passive transition potential. The grain boundary segregations of Si and Mn played a critical role in the initiation of GBD, and an electrochemical micro-couple (EMC) mechanism based on the Si and Mn segregations was proposed to reveal GBD initiation. EMC potential difference between high Si-Mn grain boundary and grain interior was greater than that between low Si-Mn grain boundary and grain interior, resulting in that GBD initiated at high Si-Mn grain boundary. The detailed EMC mechanism of GBD initiation was discussed in this work.

Study on microstructure and tensile damage evolution of 2205 duplex steel at different solution temperatures

2205 dual-phase steel was subjected to solution heat treatment experiments at 1000℃～1160℃. Electron backscatter diffraction (EBSD) was used to analyze the evolution of its microstructure; the evolution of its surface damage was analyzed by a tensile testing machine combined with digital image correlation (DIC). The results show that the FCC phase in the microstructure of 2205 dual-phase steel grows into strips after solid solution treatment. With the increase of the solution temperature, local phase boundary dissolution and fracture of the FCC phase occur, the yield strength and tensile strength of the stainless steel plate after heat treatment are the same, showing a downward trend. 2205 dual-phase steel presents the morphological characteristics of ductile fracture. The average strain factor of the critical large deformation region and the small deformation region of the original specimen are both maximum. The average strain factor at 1080℃ specimen is the smallest. With the increase in annealing temperature, the speed of damage deformation becomes slower. At different solution temperatures, in 2205 dual-phase steel, the austenite texture type changes to a certain extent, but eventually, a typical brass texture is formed; that is, the brass texture is the main texture, accompanied by a certain strength, the S texture. The grain orientations in the BCC phase are concentrated between {100}<011> and {112<110>, forming a significant a-fiber texture (<110>//RD).

Understanding PTSD Symptoms Resulting from Childhood Emotional Abuse and Boundary Dissolution: The Mediating Role of Narcissistic Pathology

ABSTRACT Emotional abuse and neglect and boundary dissolution in caregiver-child relationships are considered risk factors for the emergence of psychopathology as well as impairments in children’s self-system. The current study examined the associations between emotional abuse, neglect, and various types of boundary dissolution experienced during adolescence on young adults’ current narcissistic vulnerability, narcissistic grandiosity, and PTSD symptoms. A community sample of 686 young adults who self-reported experiences of emotional abuse and neglect and boundary dissolution as adolescents completed a series of questionnaires online. A mediation model incorporating parentification, triangulation, psychological control, and narcissistic pathology was used to examine the contribution of emotional abuse, emotional neglect, boundary dissolution, and narcissistic pathology to participants’ PTSD symptoms. The results indicated direct effects between emotional abuse and PTSD symptoms and between boundary dissolution and PTSD symptoms. An indirect effect was found between boundary dissolution and PTSD symptoms via the mechanism of narcissistic pathology. These findings underscore the need for clinicians to be aware of the adverse effects of emotional abuse and boundary dissolution in childhood on PTSD symptoms, and the potential adverse effects of boundary dissolution on the self-system.

Simulation of Flow Field of Solution Mining Salt Cavities for Underground Gas Storage

Abstract Salt cavern solution mining is a complicated process of fluid dynamics and chemical dynamics, including salt boundary dissolution, cavern expansion, brine flow, and species transport. The reaction processes occur simultaneously and interact with each other. In this study, a multiphysical coupled model is established to evaluate the real-time three-dimensional salt cavern shape expansion, the velocity field, and the brine concentration distribution. Then, the predicted results are compared with the field data of a Jintan Gas Storage Well in China. The average relative deviations with the turbulent flow are 5.7% for outlet brine concentration and 4.0% for cavern volume. The results show that salt cavern can be divided into four regions, including the shock region, plume region, reflow region, and suction region. The results also indicate that the turbulent flow will stimulate the formation of the vortex, thus affecting the distribution of brine concentration. And, the brine concentration distribution primarily influences cavern corrosion. The results suggest that adjusting the inject velocity and the tube position can change the cavern construction rate and the cavern shape. Overall, these results have guiding significance for the design and engineering practice of salt cavern construction for energy storage.

A Physiologically Based Pharmacokinetic Model for Studying the Biowaiver Risk of Biopharmaceutics Classification System Class I Drugs With Rapid Elimination: Dexketoprofen Trometamol Case Study.

Biowaiver based on the biopharmaceutics classification system (BCS) has been widely used in the global market for the approval of new generic drug products to avoid unnecessary in vivo bioequivalence (BE) studies. However, it is reported that three out of four formulations of dexketoprofen trometamol (DEX) tablets (BCS class I drug) failed the first BE study. The aim of this study was to determine whether the current biowaiver standard is reasonable for DEX. Thus, we successfully established a physiologically based pharmacokinetic (PBPK) model for DEX and examined the effects of dissolution, permeability, and gastric emptying time on DEX absorption under BCS-based biowaiver conditions using sensitivity analyses. Parameter sensitivity analysis showed that the dissolution rate in pH 1.2 media, permeability, and liquid gastric emptying time were sensitive parameters of Cmax. Therefore, gastric emptying variation was introduced into the PBPK model, and virtual BE studys were conducted on original research formulation and the formulation of the boundary dissolution rate (f2 = 50) prescribed by the biowaiver guideline. The virtual BE results showed dissolution rate changes within the biowaiver range will not cause high non-BE ratio, indicate waive of DEX generic drugs would not lead the risk of Cmax when generic products satisfy the requirements of biowaiver guideline. However, the effect of excipients on gastric emptying as a sensitive factor needs to be further studied when the rapid elimination of BCS class I drug is biowaived.

Effect the hot deformation on austenite structure of the carbon steel

Purpose. Determination influence temperature and degree of hot plastic deformation carbon steel on the development secondary recrystallization of the austenite. M ethodology. The carbon steels with a concentration of carbon by 0.55 and 0.65%, which correspond to the maximum and minimum values within the brand composition for all-rolled railway wheels, were used as material for the research. The number of other chemical elements met requirements of the documentation for railway wheels. The samples for research had the form of cylinders with a diameter of 20 and a height of 40 mm. Different degrees of plastic deformation were obtained during compression with a deformation rate of 10-3 s-1. Chamber-type electric heating furnaces were used to heat the samples to temperatures of the hot pressing. When heating samples, measures are taken to prevent oxidation and a local decrease concentration of the carbon atoms on their surfaces. After heat treatment of the samples and mechanical preparation of the surface, detection of the structure of austenite was carried out using of the etching based on a mixture of solutions hydrochloric and picric acids. The structure of the steels was investigated under a light microscope. The size of the austenite grain was determined by the methods of quantitative metallographic. Findings. The study structure of the carbon steel determined that under conditions of increasing the annealing temperature, the occurrence of structural heterogeneity of the austenite is caused by a change at mechanism of the development secondary recrystallization. Starting from 10% of hot pressing, in proportion to the degree of plastic deformation, development secondary recrystallization by the mechanism of movement of the large-angle boundaries leads to grinding of the austenite grain and the formation of a homogeneous structure. At degrees of hot deformation less than 10%, the density of dislocations is not enough to form a nucleus for the development secondary recrystallization by the mechanism of movement of the large-angle boundaries. As a result, recombination of the dislocations in grains of hot deformed austenite will occur much faster, which will lead to the separation of grains into fragments. Their size will be determined by the density of dislocations introduced during hot pressing. Disorientation angles between fragments have intermediate values between boundaries with large disorientation angles and subboundaries, which determines their low mobility. For such a structure, development of the secondary recrystallization in austenite will occur by the mechanism of grain boundary dissolution. As a result, there is significant heterogeneity structure of the austenite, which is determined by the difference in sizes between neighboring grains up to several times. Originality. Depending on the conditions of hot pressing of the carbon steel, the value of plastic deformation is determined, which separates development the secondary recrystallization of the austenite by qualitatively different mechanisms. At a low value of hot deformation, when the density of dislocations is not sufficient for the formation of a nucleus of the secondary recrystallization by the mechanism movement of the large-angle boundaries, the growth austenite grains occurs by the mechanism of dissolution of the grain boundaries. Practical value. Determining effect temperature and degree of hot plastic deformation on the mechanism of the development secondary recrystallization will allow to the optimize tenology crimping the blank of the all-rolled railway wheel.

Electrochemical Micro-Couple Mechanism Based on Si and Mn Segregations Revealing the Initiation of Grain Boundary Dissolution for Q235 Carbon Steel

Electrochemical Micro-Couple Mechanism Based on Si and Mn Segregations Revealing the Initiation of Grain Boundary Dissolution for Q235 Carbon Steel

Applications of Wrought Austenitic Stainless Steel Corrosion Testing to Laser Powder Bed Fusion 316L

Recent developments in the 3D printing of austenitic stainless steels have led to the need for standardization of electrochemical techniques used to assess the corrosion performance of these alloys. Currently, ASTM standards for austenitic stainless focus on assessing their resistance to different modes of corrosion such as pitting, crevice, and intergranular corrosion. Due to the complexity of the additive process, selective corrosion occurs in microstructural features such as cellular structures and melt pool boundaries. Standardized corrosion testing needs to incorporate these microstructural features. This study characterizes the corrosion behavior of laser powder bed fusion stainless steel in a variety of ASTM standards with special attention to melt pool boundary dissolution, cellular structures, and intergranular corrosion.

Affective Appraisal Mediates the Association between Mother–Child Boundary Dissolution and Emerging Adult Functioning across Nations

Parent-child boundary dissolution (PBD) has been found to negatively impact offspring well-being in Western cultures, although cross-cultural findings have been mixed. Given that Western measures of PBD may have a different meaning for different cultures, we examined emerging adults’ reports of maternal PBD (psychological control, infantilization, enmeshment, role reversal), their affective appraisal, and functioning in the United States (n = 119), India (n = 104), and South Korea (n = 101). Indians rated mothers as higher on all four PBD dimensions but felt more positive in response to three dimensions than Americans and South Koreans. Findings indicate that affective appraisal of maternal PBD mediated the relationship between dimensions of PBD and functioning. Results suggest that PBD may not be uniformly experienced as negative across cultures.

Self-Boundary Dissolution in Meditation: A Phenomenological Investigation

A fundamental aspect of the sense of self is its pre-reflective dimension specifying the self as a bounded and embodied knower and agent. Being a constant and tacit feature structuring consciousness, it eludes robust empirical exploration. Recently, deep meditative states involving global dissolution of the sense of self have been suggested as a promising path for advancing such an investigation. To that end, we conducted a comprehensive phenomenological inquiry into meditative self-boundary alteration. The induced states were systematically characterized by changes in six experiential features including the sense of location, agency, first-person perspective, attention, body sensations, and affective valence, as well as their interaction with meditative technique and overall degree of dissolution. Quantitative analyses of the relationships between these phenomenological categories highlighted a unitary dimension of boundary dissolution. Notably, passive meditative gestures of “letting go”, which reduce attentional engagement and sense of agency, emerged as driving the depth of dissolution. These findings are aligned with an enactive approach to the pre-reflective sense of self, linking its generation to sensorimotor activity and attention-demanding processes. Moreover, they set the stage for future phenomenologically informed analyses of neurophysiological data and highlight the utility of combining phenomenology and intense contemplative training for a scientific characterization of processes giving rise to the basic sense of being a bounded self.

Highly porous Sr-doped TiO2 ceramics maintain compressive strength after grain boundary corrosion

Maintaining sufficient mechanical support during bone healing is an essential property for ceramic bone scaffolds. However, grain boundary (GB) dissolution may compromise the mechanical strength of polycrystalline ceramics in the physiological environment. Therefore, we investigated the GB formation and its impact on the compressive strength and corrosion behavior in TiO2 scaffolds doped with calcium and strontium. To alter the GB composition and densification process, sintering conditions were altered. Prolonged sintering times and increased sintering temperature led to improved densification and increased strength in Ca-doped scaffolds. However, dissolution of the resulting amorphous GBs caused a significant loss of compressive strength when exposed to an acidic environment. In contrast, a crystalline SrTiO3 GB phase present in Sr-doped scaffolds, for which increased sintering temperature combined with rapid cooling led to a significantly improved compressive strength. Formation of SrTiO3 crystals in the GBs maintained the strength for over 4 weeks in an acidic environment.