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1.
Health Commun ; : 1-12, 2024 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-39044550

RESUMO

The doctor-patient relationship in China has become increasingly tense, with patients lacking trust in doctors. Meanwhile, online healthcare flourished, accelerated by the COVID-19 pandemic. This study utilized the direct and indirect pathway model of clinician-patient communication to health outcomes and online trust theory to examine the associations between online patient-centered communication (OPCC), benevolence and ability trust in doctors, negative online health information seeking experiences, and willingness to recommend doctors. The findings revealed that benevolence and ability trust mediated the relationship between OPCC and willingness to recommend doctors. Additionally, when participants had a high level of negative online health information seeking experiences, OPCC had a stronger effect on ability trust; meanwhile, the mediation effect of ability trust between the relationship of OPCC and willingness to recommend was stronger. This study also discussed theoretical and practical implications.

2.
Patient Educ Couns ; 124: 108283, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38593482

RESUMO

OBJECTIVE: This study aimed to explore the relationship between health-related social media use and HPV-related health knowledge, attitudes, and practices (KAP). METHOD: Data were derived from a subset of the national cohort from the 2022 Health Information National Trends Survey (HINTS 6), including only women aged 21 to 65 years old (n = 2013). Ordinary least squares regression and structural equation modeling were used to answer the research question and test hypotheses. RESULTS: Participants with a family history of cancer, higher education, and White showed more HPV knowledge. Older females were associated with lower HPV knowledge, less worry and fewer timely cervical cancer screening. Additionally, HPV knowledge positively predicted worry and cervical cancer screening. Health-related social media use positively predicted HPV knowledge, worry, and cervical cancer screening. CONCLUSION: This study identified populations with HPV knowledge and hesitated cervical cancer screening and tested hypothesized models that combine social media use with the KAP survey. PRACTICE IMPLICATIONS: Future health interventions should strategically leverage the role of social media to enhance public awareness of HPV knowledge and cancer concerns. By promoting HPV knowledge and awareness, such interventions can subsequently encourage timely cervical cancer screening.


Assuntos
Detecção Precoce de Câncer , Conhecimentos, Atitudes e Prática em Saúde , Infecções por Papillomavirus , Mídias Sociais , Neoplasias do Colo do Útero , Humanos , Feminino , Mídias Sociais/estatística & dados numéricos , Neoplasias do Colo do Útero/diagnóstico , Neoplasias do Colo do Útero/psicologia , Pessoa de Meia-Idade , Adulto , Detecção Precoce de Câncer/psicologia , Estudos Transversais , Infecções por Papillomavirus/diagnóstico , Idoso , Inquéritos e Questionários , Estados Unidos , Ansiedade/psicologia , Adulto Jovem , Programas de Rastreamento
3.
Int Immunopharmacol ; 130: 111805, 2024 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-38457930

RESUMO

OBJECTIVE: To elucidate the mechanism of Pentraxin 3 (PTX3) in the pathogenesis of psoriasiform dermatitis using Ptx3-knockout (Ptx3-KO) background mice. METHODS: An Imiquimod (IMQ)-induced murine psoriatic model was created using Ptx3-KO (Ptx3-/-) and wild-type (Ptx3+/+) mice. Skin lesion severity and expression of inflammatory mediators (IL-6 and TNFα) were assessed using PASI score and ELISA, respectively. Cutaneous tissues from the two mice groups were subjected to histological analyses, including HE staining, Masson staining, and Immunohistochemistry (IHC). The PTX3, iNOS, COX2, and Arg1 expressions were quantified and compared between the two groups. We used RNA-seq to clarify the underlying mechanisms of the disease. Flow cytometry was used to analyze systemic Th17 cell differentiation and macrophage polarization. RESULT: The psoriatic region exhibited a higher PTX3 expression than the normal cutaneous area. Moreover, PTX3 was upregulated in HaCaT cells post-TNFα stimulation. Upon IMQ stimulation, Ptx3-/- mice displayed a lower degree of the psoriasiform dermatitis phenotype compared to Ptx3+/+ mice. Consistent with the RNA-seq results, further experiments confirmed that compared to the wild-type group, the PTX3-KO group exhibited a generally lower IL-6, TNFα, iNOS, and COX2 expression and a contrasting trend in macrophage polarization. However, no significant difference in Th17 cell activation was observed between the two groups. CONCLUSIONS: This study revealed that PTX3 was upregulated in psoriatic skin tissues and TNFα-stimulated HaCaT cells. We also discovered that PTX3 deficiency in mice ameliorated the psoriasiform dermatitis phenotype upon IMQ stimulation. Mechanistically, PTX3 exacerbates psoriasiform dermatitis by regulating macrophage polarization rather than Th17 cell differentiation.


Assuntos
Proteína C-Reativa , Dermatite , Psoríase , Componente Amiloide P Sérico , Animais , Camundongos , Proteína C-Reativa/genética , Proteína C-Reativa/metabolismo , Ciclo-Oxigenase 2/genética , Ciclo-Oxigenase 2/metabolismo , Dermatite/metabolismo , Dermatite/patologia , Modelos Animais de Doenças , Imiquimode/farmacologia , Interleucina-6/metabolismo , Macrófagos/patologia , Psoríase/metabolismo , Psoríase/patologia , Componente Amiloide P Sérico/genética , Componente Amiloide P Sérico/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Humanos , Progressão da Doença , Camundongos Knockout , Camundongos Endogâmicos C57BL
4.
Health Commun ; : 1-10, 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38413578

RESUMO

News coverage of the human papillomavirus (HPV) vaccine grew rapidly in China in 2016 when the vaccine was approved. Drawing upon framing theory, the present study analyzed the content of 491 Chinese newspaper reports on the HPV vaccine published between June 2000 and December 2018 to investigate what and how information and valence about the vaccine was relayed to the public. The results indicated that, while the Chinese media failed to provide comprehensive and accurate information about HPV and the HPV vaccine, they showed a positive evaluation of the HPV vaccine demand and market. In addition, there was a decline in negative coverage after the vaccine was approved. This study extended the literature on HPV vaccine coverage by combining issue-specific framing and valence framing, considering the Chinese-specific vaccine market for presentation and the value of such products, which is rare in previous studies. Practical implications of the findings for health promotion were also discussed.

5.
Front Microbiol ; 15: 1325466, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38384268

RESUMO

Objective: Investigating the causal relationship between Lachnospiraceae and Appendicular lean mass (ALM) and identifying and quantifying the role of Aminopeptidase O Protein (AOPEP) as a potential mediator. Methods: The summary statistics data of gut microbiota composition from the largest available genome-wide association study (GWAS) meta-analysis conducted by the MiBioGen Consortium (n = 13,266). Appendicular lean mass data were obtained from the UK-Biobank (n = 450,243). We conducted bidirectional two-sample Mendelian randomization (MR) analysis using summary-level data from GWAS to investigate the causal relationship between Lachnospiraceae and ALM. Additionally, we employed a drug-targeted MR approach to assess the causal relationship between AOPEP and ALM. Finally, a two-step MR was employed to quantitatively estimate the proportion of the effect of Lachnospiraceae on ALM that is mediated by AOPEP. Cochran's Q statistic was used to quantify heterogeneity among instrumental variable estimates. Results: In the MR analysis, it was found that an increase in genetically predicted Lachnospiraceae [OR = 1.031, 95% CI (1.011-1.051), P = 0.002] is associated with an increase in ALM. There is no strong evidence to suggest that genetically predicted ALM has an impact on Lachnospiraceae genus [OR = 1.437, 95% CI (0.785-2.269), P = 0.239]. The proportion of genetically predicted Lachnospiraceae mediated by AOPEP was 34.2% [95% CI (1.3%-67.1%)]. Conclusion: Our research reveals that increasing Lachnospiraceae abundance in the gut can directly enhance limb muscle mass and concurrently suppress AOPEP, consequently mitigating limb muscle loss. This supports the potential therapeutic modulation of gut microbiota for sarcopenia. Interventions such as drug treatments or microbiota transplantation, aimed at elevating Lachnospiraceae abundance and AOPEP inhibition, synergistically improve sarcopenia in the elderly, thereby enhancing the overall quality of life for older individuals.

6.
Health Commun ; 39(5): 906-914, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-36941529

RESUMO

Autobiographical accounts on social media could play an essential role in shaping the public's understanding of illnesses and dispelling illness-related stigma. This study examined how people living with depression describe their illness experiences on Douyin, China's leading video-sharing platform, through content analysis. It finds that most videos were created by young women who have lived with the illness for over three years. The top three topics were patient psychology, experience sharing, and knowledge and medical advice. These videos provided an overall non-stigmatizing portrayal of depression, with more than 80% of the influencers using challenge cues. However, stigma cues contributed to the virality of the videos. The theoretical and practical implications of the study were discussed.


Assuntos
Depressão , Mídias Sociais , Humanos , Feminino , Gravação em Vídeo , Estigma Social
7.
Health Promot Int ; 38(5)2023 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-37837409

RESUMO

Health information literacy (HIL), as an essential part of the wellbeing of citizens, is a crucial indicator used to measure a country's primary public health level. The present study collected 1051 samples in southern China to examine the factors predicting HIL. The results showed that males, those less educated, and older adults had lower HIL. Television exposure, unofficial Internet exposure, trust in government and trust in doctors and medical institutions were positively associated with HIL. In contrast, newspapers, radio exposure and trust in web celebrities were negatively associated with HIL. Official Internet media exposure helps to bridge the HIL knowledge gap generated by differences in education level, while trust in celebrities-especially web celebrities-could widen the HIL knowledge gap. This study extends the knowledge gap theory in health communication in the Chinese context and provides pathways for future health interventions.


Assuntos
Letramento em Saúde , Masculino , Humanos , Idoso , Inquéritos e Questionários , Escolaridade , China
8.
Infect Drug Resist ; 16: 5209-5222, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37589015

RESUMO

Liver abscesses caused by Clostridium perfringens are rare but rapidly fatal. In only a few days, patients progress from liver abscess to sepsis, intravascular hemolysis, multiple organ failure, and even death. These abscesses often occur in patients after trauma or surgery or in those with immunodeficiency. Because patients only show non-specific symptoms such as fever and abdominal pain in the early stage, they can easily be misdiagnosed and miss the therapeutic window, resulting in a poor prognosis. The diagnosis of Clostridium perfringens liver abscess mainly depends on computed tomography (CT), needle aspiration, and/or blood culture. After diagnosis, treatments such as antibiotic therapy, surgical abscess drainage, blood transfusion as needed, and correction of metabolic disturbances must be immediately administered to prevent severe complications. Here, we present two cases of liver abscess due to Clostridium perfringens infection. Both patients initially presented only with fever, abdominal pain, and jaundice, symptoms that were easily confused with cholangitis caused by cholelithiasis. The patients then progressed rapidly and, despite receiving antimicrobial and multimodal sepsis treatment, both eventually died of multiple organ dysfunction syndrome. Clinicians should be on high alert for Clostridium perfringens liver abscesses disguised as biliary disease. Early diagnosis and treatment with the appropriate antibiotics and surgery are fundamental for the survival of the affected patients.

9.
Mater Horiz ; 10(10): 4470-4479, 2023 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-37526630

RESUMO

The majority of polymer-based materials demonstrate expansion upon absorbing water from the air. Mechanical metamaterials provide an interesting way to achieve unusual hygroscopic deformation. However, previous studies have only accommodated the limited tunability of negative hygroscopic expansion by theoretical analysis but have never involved other deformation modes. This work proposes modular reprogrammable 3D moisture-sensitive mechanical metamaterials with switchable hygroscopic deformation modes, which are built up of multi-material 3D-printed bi-material curved strips and cubic nodes. Depending on the geometrical parameters and spatial layouts of the curved strips, the metamaterials exhibit tunable coefficient of hygroscopic expansion from negative to positive. In addition to homogeneous deformation, complex 3D hygroscopic deformation modes can be achieved including shear and twist. More interestingly, the metamaterials are reprogrammable since all the deformation modes can be switched by modular disassembling and reassembling of the curved strips, just like LEGO building blocks. This work demonstrates a feasible approach to achieve customized 3D hygroscopic deformation through easy block building for specific engineering applications including eliminating hygroscopic stress, shape morphing structures, and smart actuators.

10.
Digit Health ; 9: 20552076231186064, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37434728

RESUMO

Background: Artificial intelligence (AI) technologies are transforming medicine and healthcare. Scholars and practitioners have debated the philosophical, ethical, legal, and regulatory implications of medical AI, and empirical research on stakeholders' knowledge, attitude, and practices has started to emerge. This study is a systematic review of published empirical studies of medical AI ethics with the goal of mapping the main approaches, findings, and limitations of scholarship to inform future practice considerations. Methods: We searched seven databases for published peer-reviewed empirical studies on medical AI ethics and evaluated them in terms of types of technologies studied, geographic locations, stakeholders involved, research methods used, ethical principles studied, and major findings. Findings: Thirty-six studies were included (published 2013-2022). They typically belonged to one of the three topics: exploratory studies of stakeholder knowledge and attitude toward medical AI, theory-building studies testing hypotheses regarding factors contributing to stakeholders' acceptance of medical AI, and studies identifying and correcting bias in medical AI. Interpretation: There is a disconnect between high-level ethical principles and guidelines developed by ethicists and empirical research on the topic and a need to embed ethicists in tandem with AI developers, clinicians, patients, and scholars of innovation and technology adoption in studying medical AI ethics.

11.
Materials (Basel) ; 16(3)2023 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-36770027

RESUMO

The effect of Mo content of 1400 MPa-grade high-strength bolt steel on hydrogen diffusion behavior and the hydrogen evolution reaction were studied using a hydrogen permeation experiment, potentiodynamic polarization tests, thermal desorption spectroscopy, and the first-principle calculation. Two 1400 MPa-grade high-strength bolt steels with different Mo content were used. Based on the potentiodynamic polarization tests, both steels' electrochemical behavior was similar in the test range. The hydrogen permeation experiment showed that the process of hydrogen adsorption and absorption was significantly promoted, and hydrogen desorption and recombination were slightly promoted, with the Mo content increasing from 0.70 to 1.09 wt%. The thermal desorption spectroscopy showed the overall reaction of hydrogen permeation and evolution. The increasing Mo content facilitated hydrogen entry behavior and increased the hydrogen content. According to the first-principle calculation and the density functional theory, this phenomenon is induced by the stronger bonding ability of Mo-H than Fe-H. This work could guide the design of 1400 MPa-grade high-strength bolt steel.

12.
Nanomaterials (Basel) ; 12(23)2022 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-36500928

RESUMO

A new catalyst, copper oxide/graphene oxide-diatomaceous earth (CuO/GO-DE), was prepared by the ultrasonic impregnation method. The optimal conditions for catalyst preparation were explored, and its structure and morphology were characterized by BET, XRD, SEM, TEM, FTIR, Raman and XPS. By taking ciprofloxacin as the target pollutant, the performance and reusability of CuO/GO-DE to degrade antibiotic wastewater was evaluated, and the optimal operating conditions were obtained. The main oxidizing substances in the catalytic system under different pH conditions were analyzed, as well as the synergistic catalytic oxidation mechanism. The intermediate products of ciprofloxacin degradation were identified by LC-MS, and the possible degradation process of ciprofloxacin was proposed.

13.
Mater Horiz ; 9(11): 2835-2845, 2022 10 31.
Artigo em Inglês | MEDLINE | ID: mdl-36043385

RESUMO

Mechanical metamaterials are of great interest due to their counterintuitive deformation under various physical fields. However, the research on metamaterials responding to moisture is still rare and controllable hygroscopic deformation is vital for sensoring, actuating, and stress elimination in a moisture environment. Inspired by the hygroscopic deformation of pinecones, this work studies 2D moisture-sensitive mechanical metamaterials exploiting bi-material curved strips as building blocks by simulations and experiments, which especially demonstrates repeatable programming ability to realize customized unusual hygroscopic deformations. Depending on the structural design of geometrical parameters and material configurations, the metamaterials exhibit a tunable coefficient of hygroscopic expansion from negative to positive, and unusual hygroscopic deformation modes including anisotropic, shearing, gradient, bending, and 3D deformation of 2D structures. Programmable metamaterials of arbitrary hygroscopic deformation are achieved by pixelated design and coding the building blocks. More importantly, the hygroscopic deformation is re-programmable by adopting erasable moisture-proof coatings on specific areas of metamaterials, i.e., it can continuously provide different customized deformation modes in a sample.


Assuntos
Molhabilidade , Impressão Tridimensional
14.
ACS Appl Mater Interfaces ; 14(31): 35905-35916, 2022 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-35880735

RESUMO

Mechanical metamaterials pave a way for designing and optimizing microstructure topology to achieve counterintuitive deformation including negative Poisson's ratio (NPR) and negative thermal expansion (NTE). Previous studies were always limited to single anomalous mechanical or thermal deformation, but current applications for high-precision mechanical or optical equipment always require their combination and customized and anisotropic deformation parameters. This work develops programmable two-dimensional (2D) mechanical metamaterials based on chiral and antichiral structures constructed with curved bimaterial strips to produce tailorable NPR and arbitrary thermal deformation. The coefficient of thermal expansion of the mechanical metamaterials is tunable on a large scale across negative, near-zero, and positive values depending on the bimaterial configurations and geometrical parameters of curved strips, while the value of NPR is mainly determined by the radian. Furthermore, it is programmable by coding the unit cells to exhibit customized and anisotropic thermal deformation combining homogeneous, gradient, and shear modes. The proposed mechanical metamaterials are fabricated by multimaterial three-dimensional (3D) printing, and the unusual deformation modes are verified experimentally, which is well in agreement with the results of finite element analysis. This work demonstrates a feasible approach to achieving customized mechanical and thermal deformation through easy block building for specific engineering applications including eliminating thermal stress, shape morphing, and smart actuators.

15.
IEEE J Biomed Health Inform ; 26(8): 3976-3987, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35290194

RESUMO

Automatic spine and vertebra segmentation from X-ray spine images is a critical and challenging problem in many computer-aid spinal image analysis and disease diagnosis applications. In this paper, a two-stage automatic segmentation framework for spine X-ray images is proposed, which can firstly locate the spine regions (including backbone, sacrum and ilium) in the coarse stage and then identify eighteen vertebrae (i.e., cervical vertebra 7, thoracic vertebra 1-12 and lumbar vertebra 1-5) with isolate and clear boundary in the fine stage. A novel Attention Gate based dual-pathway Network (AGNet) composed of context and edge pathways is designed to extract semantic and boundary information for segmentation of both spine and vertebra regions. Multi-scale supervision mechanism is applied to explore comprehensive features and an Edge aware Fusion Mechanism (EFM) is proposed to fuse features extracted from the two pathways. Some other image processing skills, such as centralized backbone clipping, patch cropping and convex hull detection are introduced to further refine the vertebra segmentation results. Experimental validations on spine X-ray images dataset and vertebrae dataset suggest that the proposed AGNet achieves superior performance compared with state-of-the-art segmentation methods, and the coarse-to-fine framework can be implemented in real spinal diagnosis systems.


Assuntos
Algoritmos , Coluna Vertebral , Atenção , Humanos , Processamento de Imagem Assistida por Computador/métodos , Radiografia , Coluna Vertebral/diagnóstico por imagem , Raios X
16.
PLoS One ; 16(1): e0245691, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33493231

RESUMO

OBJECTIVE: Although progress has been made in tuberculosis (TB) treatment, China still remains one of the high-burden TB countries. One important reason that has not received sufficient scholarly attention is that Chinese individuals tend to underestimate the threat of TB. This contributed to the high rate of delay in seeking TB treatment and noncompliance with doctors' regimen. Hence, this research examined how TB knowledge affected Chinese parents' risk perceptions and their efficacy appraisal in TB treatment, and how their risk perception and efficacy appraisal affected their intentions to seek timely TB treatment for their children and adhere to doctors' regimen. METHODS: We conducted an online cross-sectional survey with 1129 parents of children attending kindergarten, primary school, and middle school in Shajing, a region with high TB incidence in China. Perceived severity of TB threat to self and to others, perceived susceptibility, response efficacy, and self-efficacy were measured, in addition to TB knowledge and intentions to seek timely TB treatment and adhere to doctors' regimens. RESULTS: Ordinal least squares regression demonstrated that TB knowledge was positively associated with perceived severity of TB threat to self, perceived severity of TB threat to others, perceived susceptibility, response efficacy, and self-efficacy, but it did not affect their medical decisions. In addition, binary logistic regression revealed that response efficacy and self-efficacy predicted both intentions positively, and perceived severity of TB threat to self only enhanced Chinese individuals' intention to follow doctors' regimens. CONCLUSION: Health education aimed at knowledge improvement may be effective in changing one's perceptions of the given health threat but may not be effective to change their behavior. Thus, practitioners need to focus on changing Chinese parents' perceptions of TB rather than simply improving their knowledge. Specifically, it is necessary to lower their efficacy in self-management and enhance their perceived infectiousness of TB.


Assuntos
Tomada de Decisões , Conhecimentos, Atitudes e Prática em Saúde , Intenção , Pais , Adolescente , Adulto , Criança , Pré-Escolar , China/epidemiologia , Humanos , Masculino , Autoeficácia , Tuberculose/epidemiologia , Tuberculose/terapia
17.
Materials (Basel) ; 13(11)2020 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-32503175

RESUMO

The new magnetostrictive material Fe-Ga alloy has drawn considerable attention due to its excellent performance. The microstructure of the Fe-Ga alloy, which varies with the state of preparation or processing, not only affects the magnetostriction but also the mechanical service stability, i.e., the stress corrosion cracking (SCC) property. In this paper, we report a comparison of the SCC behaviors for two states of Fe85Ga15 alloys by using constant load experiments and the electrochemical method. Results showed that the hot-rolled Fe85Ga15 alloy exhibited better mechanical properties compared to the as-cast Fe85Ga15 alloy. SCC was found in both Fe85Ga15 alloys in a 3.5 wt % NaCl solution, and the as-cast alloy was more sensitive to SCC. The normalized thresholds of SCC for the as-cast and hot-rolled Fe85Ga15 alloys are 0.34 and 0.81, respectively. Furthermore, results also indicated that the SCC mechanism is an anodic dissolution for the Fe85Ga15 alloy.

18.
Materials (Basel) ; 12(24)2019 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-31861057

RESUMO

The primary task of automotive industry materials is to guarantee passengers' safety during a car crash. To simulate a car crash, the influence of strain rates on mechanical properties and fracture behavior of medium Mn steels with different Si content (0Si without δ-ferrite and 0.6Si with about 20% δ-ferrite) was conducted using the uniaxial tensile test. The results show that ultimate tensile strength is higher, whereas total elongation is lower in 0Si than in 0.6Si. As the strain rate increases, ultimate tensile strength and total elongation decrease in both 0Si and 0.6Si; nonetheless, total elongation of 0.6Si decreases faster. Meanwhile, the area reduction of 0.6Si increases as the strain rate increases. The microcrack's number on a rolling direction (RD)-transverse direction (TD) surface is considerably increased; nonetheless, the microcrack's size is restrained in 0.6Si compared with 0Si. Microcracks start at γ(α')/α-ferrite interfaces in both 0Si and 0.6Si, whereas little nucleation sites have also been found at (γ(α')+α-ferrite)/δ-ferrite boundaries in 0.6Si. Meanwhile, δ-ferrite reveals a higher capacity for microcrack arrest. As the strain rate decreases, increased lower crack growth results in fine and even dimples on fractographs with abundant second cracks on fractographs; meanwhile, the small microcrack's number increases, while the large microcrack's number decreases on an RD-TD surface.

19.
Materials (Basel) ; 12(10)2019 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-31126131

RESUMO

When 2205 duplex stainless steel (DSS) is immersed in simulated seawater under high hydrostatic pressure, or in an electrochemically hydrogen charged state, a spindle-shaped product is found in the ferrite phase that seriously deteriorates the mechanical properties of 2205 DSS. This paper systematically studied the composition, structure, and properties of the hydrogen charging product. The results of a slow strain rate tensile test show that the hydrogen charging product evidently reduces the elongation of 2205 DSS, and microcracks mainly initiate at the interface between the hydrogen charging product and the ferrite matrix at either a low or a high strain rate. However, the elongation recovers to that of the hydrogen free sample after heating the sample at 300 °C for 0.5 h. The nano-hardness and reduced modules of the product are higher than those of the ferrite and austenite phases. An element analysis by energy dispersive spectroscopy (EDS) and secondary ion mass spectrometry (SIMS) indicates that the Ni and H contents in the hydrogen charging product are higher than in the normal ferrite area, and X-ray diffraction shows the characteristic peak of iron hydride at 40.07°. Moreover, a differential scanning calorimeter (DSC) test demonstrated that the phase decomposition temperature of the product is 268 °C, which coincides with the fact that it dissolves at a high temperature caused by the focused electron beam during transmission electron microscopy (TEM) analysis. All experimental results indicate that the hydrogen charging product is a hydride of FeH or (Fe, Ni)H.

20.
Materials (Basel) ; 10(11)2017 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-29135912

RESUMO

Hydrostatic pressure effects on pitting initiation and propagation in X70 steel are investigated by evaluating metastable pitting probability using electrochemical methods and immersion corrosion tests in containing chlorine ion solution. Potentiodynamic tests indicated that hydrostatic pressure can decrease the breakdown potential and lead to a reduced transpassivity region. Metastable test results revealed that hydrostatic pressure can increase metastable pitting formation frequency and promote stabilization of metastable pitting growth. Electrochemical impedance spectroscopy (EIS) results indicate that Hydrostatic pressure decreases the charge transfer resistance and increases the dissolution rate within the cavities. Corrosion test results also indicated that pitting initiation and propagation are accelerated by hydrostatic pressure. Result validity was verified by evaluating metastable pitting to predict pitting corrosion resistance.

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