Uneven Diffusion Research Articles

Early Stages of High‐Temperature Oxidation Behavior and Its Phase Evolution of 9% Ni Steel

Herein, the effects of oxygen partial pressure (5–20%) and oxidation time (0.5–6 h) on the growth behavior and phase structure of 9% Ni steel oxide layer are studied by means of high‐temperature oxidation experiment, scanning electron microscopy, and X‐ray diffraction. The results show that the inner and outer oxide layers of 9% Ni steel grow opposite to each other along the initial surface direction of the vertical matrix during the high‐temperature oxidation process. From the perspective of the phase, the phase transition of Fe2O3→Fe3O4→FeO mainly undergoes from the outside and the inside, the results of thermodynamic calculations show that <<<0, and the main factor affecting the phase transition is the diffusion concentration of free O and Fe atoms. During the high‐temperature oxidation process of 9% Ni steel, the diffusion of O and Fe atoms along grain boundaries promotes preferential oxidation at these boundaries. The columnar structure formed in the outer oxide layer of 9% Ni steel may be related to the uneven diffusion rate of Fe atoms at different positions at the interface between the inner and outer oxide layers.

Dissolution behavior and kinetics of the γ′ precipitates within a novel powder metallurgy Ni-based superalloy

Isothermal heat treatment experiments were used to studied the dissolution behavior and kinetics of the γ′ precipitates within the hot-extruded novel powder metallurgy Ni-based superalloy A1. The characteristics of the γ′ precipitates were accurately and rapidly extracted by deep learning methods. The JMAK models were established to predict the change of the area fraction of γ′ precipitates during heat treatment. The determination coefficient R2 of model is 0.99. The results indicate that the dissolution sequence, morphological evolution, and dissolution mechanisms of the three types of γ′ precipitates are different. The small-sized tertiary γ′ precipitates (γ′t) dissolve first, while the larger-sized primary γ′ precipitates (γ′p) dissolve last. After 15 min at 1120 °C, there were only a small amount of γ′ precipitates with 0.19 ± 0.03 % area fraction. And there was not significant changed over time. After 1 min at 1150 °C, the γ′ precipitates completely dissolved. During the process of low temperature subsolvus heat treatment (1060 °C, 1090 °C), the large-sized γ′s grown at the expense of consuming the small-sized γ′ precipitates, and the γ′s tend towards directional arrangement due to elastic interaction energy. During the subsolvus heat treatment process, the γ′p spilt due to elastic strain energy and the uneven diffusion of alloying elements, while neck-connected coalescence coarsening occurs due to the overlapping diffusion fields.

Preparation, thermophysical properties, and thermal shock resistance of Yb2O3-doped YSZ coatings

The yttria-stabilized zirconia (YSZ) coatings were doped with various concentrations of Yb2O3 to build a multi-component solid solution system. The effects of concentration on the phase composition, microstructure, phase stability at high temperatures, thermal conductivity, thermal expansion, fracture toughness, elastic modulus, and other thermophysical properties of the coatings were systematically analyzed. Furthermore, the mechanism through which Yb2O3 doping impacts the thermal shock resistance of YSZ coatings was elucidated. The results reveal that doping with Yb3+, which has a similar radius to Zr4+, allows the YSZ coatings to retain the tetragonal phase structure at low doping concentrations. The Yb2O3 doping can reduce the thermal conductivity of YSZ coatings due to replacement atom and oxygen vacancy defects enhancing phonon scattering and decreasing the mean free path of phonons. The 1YbYSZ coating demonstrates better thermal shock resistance owing to its high CTE and high fracture toughness resulting from its tetragonal phase, high elastic modulus and high grain boundary density. The Yb2O3 doping can form defect clusters and increase the cation diffusion path due to oxygen vacancies, which inhibits the uneven diffusion of Y3+. Therefore, Yb2O3-doped YSZ coatings demonstrate remarkable phase stability at high temperatures of 1700 °C.

Interfacial microstructure evolution and mechanical properties of TIG welding joints of AISI 304/Q235B rolled composite plates

This study presents a comprehensive characterization of the microstructure evolution and distribution of interfacial bonding properties in the original rolled plates and a welded AISI 304/Q235B clad plates. The findings reveal that an uneven diffusion layer, rich in chromium (Cr) and nickel alloy elements, is formed at the interface of the heat-affected zone during the welding process. The thickness of the diffusion layer reaches 10 μm in the overheated region. This nonuniformity results from the dilution of alloying elements from stainless steel into carbon steel. The presence of the diffusion layer contributes to the highest microhardness value at the weld metal interface. Tensile-shear experiments indicate a 22% increase in the tensile-shear strength of the overheated zone interface compared to the base metal interface, accompanied by a 30% decrease in elongation. While the diffusion layer enhances the interface shear strength, it reduces the interface plasticity, thereby increasing the risk of fracture. Fracture analysis of the overheated zone interface reveals brittle fracture characteristics, with a small amount of Cr present. In contrast, the interface of original rolled plates displays characteristics of ductile fracture, which emphasizes the intricate interaction between brittle and ductile fracture behaviors at the interface. These observations stem from the nonuniform diffusion layer, distinct microstructure distribution, and varying rates of crack propagation.

Unsettling Race, Nature, and Environment in Geography

What might it mean to “unsettle” our disciplinary understanding of race, nature, and the environment? In this introduction to the 2023 Special Issue of the Annals of the American Association of Geographers—focused on Race, Nature, and the Environment—we reflect on the meaning and practice of unsettling in a time of climate crisis, toxic legacies, uneven development, state violence, mass extinctions, carceral logics, and racial injustices that shape—and are shaped by—the (re)production of nature. We note the ascendancy of critical scholarship on race and racialization in Anglo-American geography; its uneven diffusion and unmet challenges; and the unstoppable force of insurgent thinking, abolition geography, critical race theory, Black and Indigenous geographies, scholar activism, and environmental justice praxis in taking hold and transforming the discipline. The sixteen articles in this special issue embody different ways to “unsettle” disciplinary thought across the vibrant fields of political ecology and human–environment geography. We discuss how the articles collectively grapple with timely questions of land, water, territory, and place-making; render visible the spatial and socioecological reproduction of power and violence by capital and the state; and make space for the enduring politics of struggle on multiple registers—body, home, classroom, park, city, community, region, and world.

Microstructure and mechanical properties of WRe/GH3128 alloy electron beam welded joint

This study investigates electron beam welding of WRe/GH3128 alloy, focusing on the microstructure, defects, mechanical properties, and fracture characteristics of the welded joint. Competitive grain growth within the weld, attributed to solidification rate and grain orientation, as well as the influence of electron beam keyhole oscillation on grain morphology, is analyzed. The study discusses the uneven distribution of solute concentration within the solid phase during the non-equilibrium solidification stage of the weld, along with dendritic segregation and phase transformation processes. Segregation of Cr, Re, and C elements in the interdendritic region results in abundant precipitation of σ phase and M6C. Non-equilibrium solidification phase fractions and phase transformation processes within the weld are calculated using JMartPro software. Furthermore, the potential relationship between the uneven diffusion of elements within the reaction layer and the formation of intermetallic compounds is discussed. XRD testing confirms the presence of Cr7Re3, Ni4W, Ni4Mo, and M6C within the reaction layer. The microhardness and tensile properties of the joints are evaluated, with a tensile strength of 600 MPa, representing 77% of GH3128's strength, while the elongation is only 2.5%. The increase in weld microhardness is attributed to changes in grain morphology and precipitation of M6C and σ phases, with M6C reducing joint plasticity. Cracks and defects are observed in the WRe heat-affected zone, and the role of metallurgical bonding and solid-state healing in crack repair is elucidated. Finally, an analysis is conducted on factors such as crystal microstructure defects that can lead to crack nucleation and propagation, providing separate explanations for intergranular fracture in the WRe base material and brittle fracture in the reaction layer.

The state does not live by warfare alone: War and revenue in the long nineteenth century

Previous research shows that wars contributed to the expansion of state revenues in the Early Modern period and in the twentieth century. There are, however, few cross-national studies on the long nineteenth century. Using new unbalanced panel data on wars and public revenues from 1816 to 1913 for 27 American and European countries, this article provides new evidence that military conflicts very rarely triggered lasting increases in public revenues during those years. We argue that the uneven diffusion of military innovations reduced the probability that international wars would be sufficiently intense to push state actors to seek additional resources. Moreover, the distinction between international and civil wars was blurred by the opportunities for non-state actors to mobilize military forces comparable to those of the state. Therefore, only very intense international and civil wars had a lasting impact on state revenues, but such conflicts were extremely rare, both in Europe and the Americas.

Research on corrosion mechanism of microstructure on low alloy steel in humid atmosphere

The corrosion process of low-alloy steels with three different microstructures in a humid atmosphere was systematically studied in this paper. Scanning electron microscope (SEM), transmission electron microscope (TEM), scanning Kelvin probe force microscope (SKPFM) and electrochemical measurement were conducted to characterize the microstructure, surface Volta potential and corrosion kinetic parameters of different phase. Confocal laser scanning microscope (CLSM) and X-ray diffraction (XRD) were utilized to characterize morphology and composition of rust layer. The results show that the volt potential of the substrate surface has a linear relationship with the corrosion kinetic parameters, and the structure with small micro-area potential difference and low average potential has better corrosion resistance. The ferrite in the dual phase will preferentially dissolve as an anode to form a crater, which will be filled with corrosion products, resulting in an uneven diffusion of oxygen and thus the formation of a concentration polarization. Dual phase steel will form a poorly protective rust layer, which causing the corrosion resistance analysis to be inconsistent with the final corrosion rate results.

Atomic insights into combustion mechanism of nano‐aluminum hydride

As an important hydrogen storage material, aluminum hydride is widely used in the combustion field. However, the oxidation behavior and potential mechanism of aluminum hydride nanoparticle (AHNP) in the combustion process are not clear. Molecular reactive dynamics was used to explore the oxidation behavior and mechanism of pure and core-shell AHNP with different oxide layer thickness, particle size and oxygen concentration. The simulation results show that uneven oxidation of AHNP surface presents branched distribution, and the oxidation process is carried out by the interdiffusion of O and Al. The core Al diffusion coefficient of 40 ps (1.42 × 10−4 cm2/s) is much larger than that of shell O atoms (4.90 × 10−5 cm2/s), indicating that oxidation of core-shell AHNP is dominated by the uneven diffusion of core Al into the oxide layer driven by an electrostatic force. This leads to the formation of hydrogen gas chamber of different sizes. Mean square displacement shows that core Al tends to diffuse into a thinner oxide layer. The oxide layer inhibits the diffusion of core Al and H, resulting in a slower oxidation rate. The smaller AHNP exhibits a micro-explosion oxidation accompanied by the formation of small Al clusters, and the reaction process is dominated by aluminum diffusion. The initial reaction of the larger AHNP is mainly concentrated on the surface, the subsequent oxidation processes rely on heterogeneous reactions between the oxidation phase and AlH3. Under lower oxygen concentration, AHNP shows a lower oxidation rate and heat release, where core Al and environment O atoms diffuse toward each other to form a homogeneous OAl phase. Under higher oxygen concentration, the active Al atoms diffuse outward to form a hollow spherical structure. This work provides fundamental insight into the storage and application of AHNP that serve as a high energy density fuel.

A Contemporary Look at the Polyhedral Shape Instability of Crystals Growing under Conditions of Diffusion‐Limited Supply of Building Material

AbstractThis paper intends to shed fresh light on the polyhedral shape (in)stability of crystals growing under conditions of uneven diffusion supply of building material. A simplified theoretical consideration of the phenomenon is presented; the whole crystal is regarded as material consumer (but not merely a separate face on it). Accounted is for the fact that different amounts of building material are supplied by diffusion to the diverse types of crystal faces. Besides, critical sizes of crystal faces over which they lose the ability to grow macroscopically flat (because shallow cavities are formed on them) are calculated not only for the basal faces of Zn crystals growing from highly diluted own vapors mixed in inert (in respect to this metal) gases, such as H2 and Ar, but also for the pyramidal crystal faces. So, a logical explanation is given of the long‐standing problem: why the measured critical sizes of Zn single crystals grown in inert atmospheres are much smaller than the theoretically calculated critical sizes? Finally, the widths of the macroscopically flat rims surrounding the cavities on basal faces of Zn and Cd crystals (growing under conditions of uneven diffusion supply of building material) are determined in a simplified way.

Lattice Matching and Halogen Regulation for Synergistically Induced Uniform Zinc Electrodeposition by Halogenated Ti3C2 MXenes

Dendrite growth and low Coulombic efficiency caused by uneven diffusion and electrodeposition of Zn2+ ions have emerged as a barrier to exploit the Zn metal anode. In this work, we demonstrate the stoichiometric halogenated MXenes (Ti3C2Cl2, Ti3C2Br2, and Ti3C2I2) as an artificial layer that can induce the uniform Zn deposition. The efficient redistribution effect results from the coherent heterogeneous interface reconstruction and regulated ion tiling by halogen surficial termination. The synergetic effects of high lattice matching (90%) between the adopted MXenes and Zn, as well as the positive halogen regulation, Zn2+ ions are guided to nucleate uniformly on the most extensive (000l) crystal plane of the MXene matrix and grow in a planar manner. In terms of Zn ion regulation, Cl termination is found to be more effective than O/F, Br, and I due to its moderate adsorption and diffusion coefficiency for Zn2+ ions. The Ti3C2Cl2-Zn anode achieves a life extension of over 12 times (840 h at 2 mA cm-2//1 mAh cm-2) over that of the bare Zn anode and serves more than 9000 cycles in a battery with a Ti3C2I2 cathode at a high rate of 3 A g-1. Given the abundance of lattice parameters and terminations of MXene materials, the developed strategy is expected to be extended to other metal anode systems.

Smart cities and urban inequality

ABSTRACT Smart city technologies are criticized because they might exacerbate income inequalities. Four factors are suggested to explain this phenomenon: the uneven diffusion of information and communication technologies (ICTs); that these ICTs cannot be afforded by low-income citizens; that smart cities could further human capital divides; and the involvement of private actors in the implementation of projects. These critiques are not based on empirical verification. We test whether smart urban characteristics are associated with increases in urban income inequalities, using data on urban smartness and urban income inequality for 106 European cities. Results show that smart cities are associated with lower levels of urban income inequality.

Preparing Cu2ZnSn(SxSe1−x)4 thin-film solar cells with front band gap grading by plasma sulfurization

In this paper, Cu2ZnSn(SxSe1−x)4(CZTSSe) thin-films with a front-graded band gap were prepared by plasma sulfurization. The method of selenization followed by low-temperature plasma sulfurization was adopted to effectively control the uneven diffusion of S in the absorption layer. By investigating and analyzing the grazing incidence X-ray diffraction, Raman spectroscopy, and PL spectra, the CZTSSe absorption layer with an S-rich top and S-poor bottom layer could be obtained by plasma sulfurization. The inhomogeneous distribution of S led to the formation of band gap gradients. Based on that, the band gap near the top of the absorption layer was determined to be 1.13 eV and the bottom band gap was 1.03 eV. Approximately 300 nm thick sulfur-rich CZTSSe films were found near the surface favoring an increase in the band gap at the interface, which could be attributed to a high open circuit voltage (Voc). The establishment of the band gap gradient formed a barrier towards the motion of holes towards the interface and increased the effective interfacial recombination band gap, both of which significantly reduced the interfacial recombination. Finally, the CZTSSe thin-film solar cells with a band gap gradient were prepared by plasma sulfurization exhibited a power conversion efficiency (PCE) of 8.11%. Compared with CZTSSe thin-film solar cells without post plasma sulfurization, which had a PCE of 6.98%, the Voc of the CZTSSe solar cell improved considerably from 471.37 mV to 513.93 mV; however, it had little effect on short-circuit current density (Jsc).

The winners and losers in the race to environmental sustainability: a ranking of Summer Olympic International Federation progress

Purpose: The purpose of this paper is to consolidate knowledge and benchmark the progress being made across the 32 International Federations (IFs) in the Summer Olympic Programme. Design/methodology/approach: A website content analysis, analytical hierarchy of information, and social media research was conducted to triangulate the barriers and drivers of environmental sustainability (ES) progress. This data was then analysed to empirically substantiate the findings of previous methods by exploring potential drivers of IF ES progress and communication and refining the ranking of IF ES progress. Results and findings: World Sailing is by far the most advanced IF in terms of ES progress, followed by World Athletics. Only 4 out of 32 have any sort of strategic ES plans. Only golf, surfing, football, sailing, and hockey have received any academic attention. There is a significant lack of understanding of environmental practices across sport, and their drivers/barriers. There is limited accountability with regards to ES progress and activities throughout the Olympic Movement. This has resulted in uneven diffusion of environmental activities. Originality: This paper is a new contribution to sport management and ES literature. It provides a benchmark of understanding for ES in the Summer Olympic Programme for the first time using a hierarchy of information to ground results. The exploration and comparison of the perspectives of separate sports adds to the paper's originality.

The winners and losers in the race to environmental sustainability: a ranking of Summer Olympic International Federation progress

Purpose: The purpose of this paper is to consolidate knowledge and benchmark the progress being made across the 32 International Federations (IFs) in the Summer Olympic Programme. Design/methodology/approach: A website content analysis, analytical hierarchy of information, and social media research was conducted to triangulate the barriers and drivers of environmental sustainability (ES) progress. This data was then analysed to empirically substantiate the findings of previous methods by exploring potential drivers of IF ES progress and communication and refining the ranking of IF ES progress. Results and findings: World Sailing is by far the most advanced IF in terms of ES progress, followed by World Athletics. Only 4 out of 32 have any sort of strategic ES plans. Only golf, surfing, football, sailing, and hockey have received any academic attention. There is a significant lack of understanding of environmental practices across sport, and their drivers/barriers. There is limited accountability with regards to ES progress and activities throughout the Olympic Movement. This has resulted in uneven diffusion of environmental activities. Originality: This paper is a new contribution to sport management and ES literature. It provides a benchmark of understanding for ES in the Summer Olympic Programme for the first time using a hierarchy of information to ground results. The exploration and comparison of the perspectives of separate sports adds to the paper's originality.

Social Inequality and the Future of U.S. Life Expectancy.

Despite decades of progress, the future of life expectancy in the United States is uncertain due to widening socioeconomic disparities in mortality, continued disparities in mortality across racial/ethnic groups, and an increase in extrinsic causes of death. These trends prompt us to scrutinize life expectancy in a high-income but enormously unequal society like the United States, where social factors determine who is most able to maximize their biological lifespan. After reviewing evidence for biodemographic perspectives on life expectancy, the uneven diffusion of health-enhancing innovations throughout the population, and the changing nature of threats to population health, we argue that sociology is optimally positioned to lead discourse on the future of life expectancy. Given recent trends, sociologists should emphasize the importance of the social determinants of life expectancy, redirecting research focus away from extending extreme longevity and towards research on social inequality with the goal of improving population health for all.

Effect of non-isothermal flow on chloride ion transport in saturated concrete

The presence of a temperature difference changes the mode of motion of the fluid. The macroscopic motion of the fluid causes the relative displacement between the various parts of the fluid, which in turn affects the transfer of temperature in the medium. To investigate the effect of temperature transfer coupled fluid motion on chloride ion transport in concrete, a mesoscopic model of chloride ion transport in non-isothermal flow of concrete was established and compared with experimental data. Based on the finite element software, the influence of temperature transfer on the internal fluid motion and chloride ion transport of concrete was analyzed. And the effect of convective motion of fluid on the temperature transfer in concrete was studied. It is found that when the heating time is the same, the dynamic viscosity of the fluid in the concrete decreases with the increase of temperature; the chloride ion concentration increases with the increase of temperature at the same depth of concrete; when considering the influence of laminar flow, the temperature is transmitted faster in the concrete and exhibits uneven diffusion from high temperature to low temperature; non-isothermal flow promotes the diffusion of chloride ions in concrete, and the higher the temperature.

Welfare for Elites: The Student Health Center at Tokyo Imperial University and the Paradox of Medicare in Japanese Meritocracy.

How did the Japanese establish a medical welfare system? In answering this question, historians of modern Japan have accentuated the assertive role of state bureaucrats, especially from those of the Home Ministry (naimushō). Historians of Japanese medicine also emphasized the role of the state. William Johnston, in his pioneering work on tuberculosis in Japan, explored the rise of a hygiene administration on this disease as a state enterprise. In the medical history of Japan, scholars highlighted the significance of the wartime period in the birth of this system. The emphasis on the Japanese wartime state is justified. The Japanese government managed to establish a national health insurance in 1935, while the United States government has not been able to establish a medical insurance for every citizen to this day. However, these scholars have not explored how welfare benefits were distributed to members of Japanese society. This article seeks to fill this historiographical gap by looking at the Student Health Center of Tokyo Imperial University (Tōdai), Japan's first state-established university founded in 1886. This university, I contend, was a critical locus in the birth of medical welfare in Japan. At this university were the most privileged medical facilities and practitioners who could provide medical services, as well as students without stable incomes of their own, thus in need of welfare support. The demand of staff of Tōdai's Student Association to establish a Student Health Center was accepted and realized in 1926, and Tōdai students became the beneficiaries of state-managed medical support. The Tōdai Student Health Center was different from other medicare facilities in that its role was not limited to save students from poverty. Student Health Center practitioners helped students check health for university admission, campus life, and job placement to be white-collar elites. Student Health Center practitioners evaluated students' health when they tried to enter Tōdai and get jobs and inculcated students in how to manage living as mental-worker "gentlemen," in coping with tuberculosis, venereal diseases, and neurotic breakdown. Also, they produced statistics about the health condition of Tōdai students, which immediately stimulated further investment in the facilities of Tōdai authorities for the center. Based on statistical data, Tōdai authorities developed a hygiene campaign against tuberculosis so that students could take advantage the of state-of-the-art treatments inexpensively. As such, Tōdai students became among the biggest beneficiaries of this process. In other words, the Student Health Center had a dual significance at Tōdai: a medicare institution as well as part of privileged campus culture. Tōdai was a symbolic locus that reveals the uneven diffusion of medical welfare benefits in Japanese society. Through the lens of this facility, this article seeks to explore the paradox of welfare in meritocracy that contributed to the formation of the elite class in modern Japan.

CB1-Antibody Modified Liposomes for Targeted Modulation of Epileptiform Activities Synchronously Detected by Microelectrode Arrays.

Temporal lobe epilepsy (TLE) is a focal, recurrent, and refractory neurological disorder. Therefore, precisely targeted treatments for TLE are greatly needed. We designed anti-CB1 liposomes that can bind to CB1 receptors in the hippocampus to deliver photocaged compounds (ruthenium bipyridine triphenylphosphine γ-aminobutyric acid, RuBi-GABA) in the TLE rats. A 16-channel silicon microelectrode array (MEA) was implanted for simultaneously monitoring electrophysiological signals of neurons. The results showed that anti-CB1 liposomes were larger in size and remained in the hippocampus longer than unmodified liposomes. Following the blue light stimulation, the neural firing rates and the local field potentials of hippocampal neurons were significantly reduced. It is indicated that RuBi-GABA was enriched near hippocampal neurons due to anti-CB1 liposome delivery and photolyzed by optical stimulation, resulting dissociation of GABA to exert inhibitory actions. Furthermore, K-means cluster analysis revealed that the firing rates of interneurons were decreased to a greater extent than those of pyramidal neurons, which may have been a result of the uneven diffusion of RuBi-GABA due to liposomes binding to CB1. In this study, we developed a novel, targeted method to regulate neural electrophysiology in the hippocampus of the TLE rat using antibody-modified nanoliposomes, implantable MEA, and photocaged compounds. This method effectively suppressed hippocampal activities during seizure ictus with high spatiotemporal resolution, which is a crucial exploration of targeted therapy for epilepsy.

Moral practices shaping HIV disclosure among young gay and bisexual men living with HIV in the context of biomedical advance

Biomedical advances in diagnostics, treatment and prevention increase the means available to reduce HIV transmission risk. Subsequent shifts in HIV status disclosure obligation and ethics may impact how those living with HIV view, enact and experience disclosure. We analysed focus group and interview data to explore how these changes are reflected in disclosure decision-making to sexual partners among young gay and bisexual men living with HIV in the USA. Three interrelated themes were identified: engaging with partners’ varying HIV knowledge; attribution of blame; and negotiating disclosure-related harms. Participants experienced blame from partners that questioned the timing of HIV testing, status disclosure and sex events without regards for viral suppression or use of pre-exposure prophylaxis. Substantial HIV stigma was described in response to disclosure, mitigated in some cases by partners’ higher HIV knowledge. Overall, an uneven diffusion of HIV treatment and prevention knowledge and continuing HIV stigma seemed to limit the translation of biomedical advances into improved disclosure experiences. Our findings suggest that young gay and bisexual men living with HIV may continue to perform much of the moral labour involved in disclosure by managing others’ reactions, correcting inaccurate sexual health information, and negotiating the risks of disclosure-related harm.