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OBJECTIVE: To investigate the relationship between ovarian volume-related parameters and in vitro fertilization (IVF) outcomes in order to establish an accurate and reliable method of determining ovarian response or IVF outcomes. STUDY DESIGN: A total of 142 women undergoing controlled ovarian stimulation with gonadotropin-releasing hormone agonist were retrospectively analyzed. In each ovary, diameters in 2 perpendicular planes were measured and calculated by applying the formula for an ellipsoid: (D1xD2x(D1+D2/2)xπ/6). The total basal ovarian volume (BOV) was calculated as the sum of the bilateral ovarian volume. Total follicular volume (TFV) was defined as sum of bilateral follicular volume. The study subjects were grouped by TFV/BOV and by TFV/BOV/stimulation days. RESULTS: A significantly higher number of oocytes was retrieved in the participants with a higher TFV/BOV (p=0.002). The patients with higher TFV/BOV/stimulation days also demonstrated a significantly higher serum estradiol level on the hCG day and a higher number of retrieved oocytes (p=0.04 and 0.02, respectively). In a multivariate analysis, the TFV/BOV/stimulation days had a significant independent effect on the number of transferred embryos (p=0.01). CONCLUSION: Ovarian volume-related dynamic parameters play an important role in predicting ovarian response and IVF outcomes.
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Fertilización In Vitro , Infertilidad Femenina/patología , Ovario/patología , Inducción de la Ovulación , Adulto , Transferencia de Embrión , Femenino , Humanos , Recuperación del Oocito , Oocitos , Embarazo , Resultado del Embarazo , Estudios RetrospectivosRESUMEN
BACKGROUND/AIMS: The purpose of this study was to investigate the association between single nucleotide polymorphisms (SNPs) in sclerostin (SOST), dickkopf (DKK), secreted frizzled-related protein (sFRP) genes and bone mineral density (BMD) in postmenopausal Korean women. METHODS: The SOST, Wnt inhibitory factor 1 (WIF1), sFRP1,sFRP2,sFRP3, sFRP4, sFRP5, DKK1, DKK2 and DKK3 polymorphisms were analyzed in 399 postmenopausal Korean women. Serum levels of bone turnover markers were measured, and BMDs at the lumbar spine and femoral neck were also examined. RESULTS: No significant differences in adjusted BMD at the lumbar spine and femoral neck were noted according to any single and combined polymorphisms measured in SOST, DKKs and sFRPs. However, osteoporosis at the femoral neck was 2.35 times more frequently observed in the AA genotype of the sFRP4 c.958C>A polymorphism compared to the non-AA genotype (95% CI 1.09-5.08, p = 0.03). Also, the CC genotype of the sFRP3 c.970C>G polymorphism had a higher rate of osteoporosis at the femoral neck compared to the GC genotype (OR 8.47, 95% CI 1.37-52.63, p = 0.049). CONCLUSIONS: Our results suggest that the sFRP3 c.970C>G and sFRP4 c.958C>A polymorphisms may be genetic factors associated with the prevalence of osteoporosis at the femoral neck in postmenopausal Korean women.
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Pueblo Asiatico/genética , Densidad Ósea/genética , Osteoporosis/genética , Polimorfismo de Nucleótido Simple , Absorciometría de Fotón , Proteínas Adaptadoras Transductoras de Señales/genética , Proteínas Morfogenéticas Óseas/genética , Quimiocinas , Proteínas del Ojo/genética , Femenino , Cuello Femoral/fisiopatología , Marcadores Genéticos/genética , Genotipo , Glicoproteínas/genética , Humanos , Péptidos y Proteínas de Señalización Intercelular/genética , Péptidos y Proteínas de Señalización Intracelular , Proteínas de la Membrana/genética , Persona de Mediana Edad , Osteoporosis/fisiopatología , Posmenopausia/genética , Proteínas Proto-Oncogénicas/genética , Proteínas Represoras/genética , República de CoreaRESUMEN
In this study, the corrosion behavior and degradation mechanism of Ti-Pt-coated stainless steel bipolar plates were investigated through electrochemical tests and surface analysis in a polymer electrolyte membrane water electrolysis (PEMWE) operating environment. The coated bipolar plate has a corrosion current density of only 1.68 × 10-8 A/cm2, which is an order of magnitude lower than that of the bare SS316L substrate (1.94 × 10-7 A/cm2), indicating that its corrosion resistance is superior to that of bare SS316L substrate. However, in the PEMWE operating environment, the protection efficiency of the coating and the corrosion resistance of the coated bipolar plate decreased. The degradation of the coated bipolar plate can be attributed to electrolyte penetration into the blistering areas of the coating layer with micro voids. Defects in the coating layer occur because of the pressure of oxygen gas generated within the coating layer under high-potential conditions, thereby exposing the substrate to the electrolyte and corrosion.
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STUDY QUESTION: Do microRNAs (miRNAs) in granulosa cells (GCs) affect oocyte maturation during ovarian follicle development? SUMMARY ANSWER: Sophisticated regulation by miRNAs in ovarian GCs may improve oocyte maturation efficiency during ovarian follicle development. WHAT IS KNOWN ALREADY: The meiotic competence of oocytes depends on the follicle's potential to undergo appropriate maturation and is an important factor in infertility therapies such as IVF. The exact function of the GCs during follicular development remains unknown. STUDY DESIGN, SIZE, DURATION: After in vitro maturation (IVM) and ovulation induction of isolated ovarian pre-antral follicles from 12-day-old female C57BL6 mice (n = 40), miRNA expression in the GCs was compared according to the maturity of the oocyte (metaphase I (MI) versus metaphase II (MII)). The miRNAs, which showed notable different expression, were modulated by transfection during IVM of follicles. MATERIALS, SETTING, METHODS: miRNA expression and candidate target gene expression in GCs of isolated murine ovarian pre-antral follicles were evaluated by real-time PCR after IVM. miR mimics and -inhibitors for selected miRNAs were transfected into the in vitro-maturated follicles, and ovulation, oocyte maturation and fertilization rates were compared. Candidate target gene expressions in GC were evaluated by quantitative PCR and immunohistochemistry using confocal microscopy. MAIN RESULTS AND THE ROLE OF CHANCE: The relative expression of mmu-let-7b (0.78 ± 0.10, P = 0.016), mmu-let-7c (0.78 ± 0.12, P = 0.029), mmu-miR-27a (0.57 ± 0.18, P = 0.016) and mmu-miR-322 (0.59 ± 0.14, P = 0.008) was significantly lower in the GCs of follicles containing MII oocytes compared with those of MI oocytes. Transfection with a mmu-miR-27a-mimic sequence decreased the oocyte maturation rate compared with that for the control (9.4 versus 18.9%, P = 0.042), and transfection with mmu-let-7c-, mmu-miR-27a- and mmu-miR-322-inhibitor sequences increased the oocyte maturation rate by 1.5- to 2.0-folds compared with that for the control (40.6, 31.6, and 30.5%versus 18.9%, P < 0.001, P = 0.013, P = 0.021, respectively). The expression of IGFBP-2 was higher in GCs of MII than in the GCs of MI, and higher in miR-inhibitor transfection groups than in miR-mimic transfection groups and controls. LIMITATIONS, REASONS FOR CAUTION: An in vitro model was used in lieu of an in vivo model because of the ease of performing miRNA transfection in cell culture. However, studies have shown similarities and differences in in vivo versus in vitro cultured follicles. The findings of the present study need to be confirmed using in vivo maturation models and extended to evaluate developmental competence. WIDER IMPLICATIONS OF THE FINDINGS: Our findings suggest that sophisticated miRNA regulation in GCs may improve oocyte maturation efficiency during ovarian follicle development. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by a grant from the Korean Health Technology R&D Project, Ministry of Health & Welfare, Republic of Korea (A111539). None of the authors has any conflicts of interest to declare.
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Técnicas de Maduración In Vitro de los Oocitos , Meiosis/genética , MicroARNs/fisiología , Folículo Ovárico/crecimiento & desarrollo , Animales , Gonadotropina Coriónica/farmacología , Femenino , Fertilización In Vitro , Células de la Granulosa/metabolismo , Células de la Granulosa/fisiología , Ratones , Ratones Endogámicos C57BL , TransfecciónRESUMEN
This study was conducted to investigate the association between the metabolic syndrome (MS), which includes a cluster of major risk factors for cardiovascular diseases, and bone mineral density (BMD) from a population-based study. This cross-sectional study was based on a nationwide representative survey data from the Korean National Health and Nutrition Examination Survey (KNHANES) 2008. A total of 3,207 subjects were included from the KNHANES 2008 and composed of men (mean age 48.4 years), premenopausal women (mean age 36.5 years) and postmenopausal women (mean age 64.8 years). The MS was identified according to the new criteria from a joint scientific statement endorsed by major organizations including the National Heart, Lung, and Blood Institute. The mean age of study participants was significantly different according to MS status (58.2 years in the MS group vs. 45.7 years in the non-MS group, P < 0.001). The association between MS and BMD at the lumbar spine and proximal femur was analyzed with adjustment for potential confounders. Although the adjusted BMD at all skeletal sites was not significantly different between participants with and without MS, an increased number of MS components was associated with low adjusted femoral neck (FN) BMD only in men (P = 0.01). After adjusting confounding factors, the triglyceride component of MS was related to low FN BMD in men, but to high BMD at all of the skeletal sites measured in postmenopausal women. The glucose component of MS showed an association with high adjusted BMD at total hip in men. Men with MS had significantly higher odds for pooled osteopenia and osteoporosis (odds ratio: 1.49, 95 % confidence interval: 1.04-2.14). In conclusion, low BMD is associated with MS in Korean men, and the association between the MS component and the BMD is different according to gender.
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Densidad Ósea/fisiología , Síndrome Metabólico/metabolismo , Adulto , Estudios Transversales , Femenino , Humanos , Masculino , Persona de Mediana Edad , Posmenopausia , PremenopausiaRESUMEN
In light of the differences in hip fracture rates between men and women of different ages, age-related changes in bone structure that lead to bone fragility might differ depending on both age and gender. To investigate age-related bone loss and geometric deterioration of the femur, hip scans of 1,504 men and 2,076 women aged 19-92 years acquired during the Fourth Korean National Health and Nutrition Examination Survey (KNHANES IV) using dual-energy X-ray absorptiometry (DXA) were analyzed with a structural analysis program. Cross-sectional area and cortical thickness with bone mineral density in men started to decline from the third decade and continued to decline at a constant rate. However, in women, these parameters remained nearly constant until the fifth decade and then declined at a more rapid rate than that seen in men. Consequently, changes in the buckling ratio, earlier onset, and continuation of increase over the lifetime were observed in men. A relatively later onset with a greater acceleration with aging was observed in women. Taken together, there were obvious gender and age differences in structural trends with age. Bone aging, i.e., bone loss and geometric deterioration, actually begins at a young age, especially in men, and osteoporosis prevention strategies should target not only the elderly but also younger individuals.
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Envejecimiento/fisiología , Fémur/fisiología , Encuestas Nutricionales , Adolescente , Adulto , Distribución por Edad , Anciano , Anciano de 80 o más Años , Fenómenos Biomecánicos/fisiología , Composición Corporal/fisiología , Densidad Ósea , Módulo de Elasticidad/fisiología , Femenino , Fémur/anatomía & histología , Cuello Femoral/anatomía & histología , Cuello Femoral/fisiología , Humanos , Masculino , Persona de Mediana Edad , República de CoreaRESUMEN
OBJECTIVES: Only a few studies have suggested the association between ovarian cysts and serum estrogen levels during tamoxifen use. However, increased estrogen levels with ovarian cysts would affect the prognosis of breast cancer; this association has not yet been studied. We aimed to investigate the association between ovarian cysts and prognostic markers in premenopausal breast cancer patients undergoing tamoxifen treatment. METHODS: A retrospective review of 65 premenopausal breast cancer patients who underwent tamoxifen treatment was performed. Serum hormone levels were measured either specifically between cycle days 2 and 5 in menstruating patients or at any time in amenorrheic participants. RESULTS: The study population consisted of premenopausal patients with (n = 23) and without ovarian cysts (n = 42). Serum estradiol (E(2)) levels and tumor markers were not statistically different based on ovarian cyst status. In the subgroup analysis, serum E(2) levels were significantly higher in menstruating women with ovarian cysts, and E(2) levels were positively correlated with serum cancer antigen 15-3 and insulin-like growth factor-1 in these women. CONCLUSIONS: Ovarian cysts during tamoxifen use may affect the markers associated with the clinical course of premenopausal breast cancer.
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Neoplasias de la Mama/sangre , Neoplasias de la Mama/tratamiento farmacológico , Quistes Ováricos/sangre , Quistes Ováricos/inducido químicamente , Premenopausia/sangre , Tamoxifeno/efectos adversos , Adulto , Amenorrea/sangre , Antineoplásicos Hormonales/administración & dosificación , Antineoplásicos Hormonales/efectos adversos , Biomarcadores de Tumor/sangre , Estradiol/sangre , Femenino , Humanos , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/sangre , Factor I del Crecimiento Similar a la Insulina/metabolismo , Menstruación/sangre , Persona de Mediana Edad , Mucina-1/sangre , Pronóstico , Estudios Retrospectivos , Tamoxifeno/administración & dosificaciónRESUMEN
In this study, an Al-Mn-Zr alloy was designed and its microstructure and corrosion behavior compared after laser welding to that of AA3003. As the results of immersion and electrochemical tests showed, both alloys had a faster corrosion rate in the fusion zone than in the base metal. Laser welding caused interdendritic segregation, and spread the intermetallic compounds (IMCs) evenly throughout in the fusion zone. This increased the micro-galvanic corrosion sites and destabilized the passive film, thus increasing the corrosion rate of the fusion zone. However, Zr in the Al-Mn alloy reduced the size and number of IMCs, and minimized the micro-galvanic corrosion effect. Consequently, Al-Mn-Zr alloy has higher corrosion resistance than AA3003 even after laser welding.
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This study delves into the atmospheric corrosion behavior of chromium-free complex-phase (CP) steel, specifically investigating the influence of wet/dry frequency and ratio in cyclic corrosion tests (CCT). The study employs a modified ISO 14993 standard CCT method, which involves salt spray, dry, and wet stages. After 15 and 30 CCT cycles, mass loss, maximum corrosion depth, and corrosion products were analyzed to gain insights into corrosion mechanisms. In general, increasing the frequency and wet/dry stage ratio in CCT extends the time for autocatalytic reactions to occur, leading to accelerated localized CP steel corrosion and increased pitting factors. However, as the rust layer thickens, uniform corrosion may also intensify, so careful considerations are necessary. This study underscores the importance of controlling the frequency and ratio of wet/dry stages in CCT for effectively analyzing localized corrosion behavior in specimens.
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In this paper, two leaking tubes were investigated among copper tubes injected with 200 and 400 ppm benzotriazole after 8 years of usage. The electrochemical tests were conducted in simulated pit-out and pit-in environments (i.e., regions outside and inside of the pit) to determine the effect of benzotriazole on the propagation of an existing pit. The electrochemical analysis results showed that 200 and 400 ppm benzotriazole exhibit relatively lower inhibition efficiency in an acidic simulated pit-in environment because of the difficulty of forming a protective film and the benzotriazole cationization.
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In order to predict the corrosion depth of a district heating pipeline, it is necessary to analyze various corrosion factors. In this study, the relationship between corrosion factors such as pH, dissolved oxygen, and operating time and corrosion depth was investigated using the Box-Behnken method within the response surface methodology. To accelerate the corrosion process, galvanostatic tests were conducted in synthetic district heating water. Subsequently, a multiple regression analysis was performed using the measured corrosion depth to derive a formula for predicting the corrosion depth as a function of the corrosion factors. As a result, the following regression formula was derived for predicting the corrosion depth: "corrosion depth (µm) = -133 + 17.1 pH + 0.00072 DO + 125.2 Time - 7.95 pH × Time + 0.002921 DO × Time".
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This study investigates the corrosion resistance of Type 316 stainless steel as a candidate material for radioactive waste disposal canisters. The viability of stainless steel is examined under groundwater conditions with variations in pH, bisulfide ions (HS-), and chloride ions (Cl-) concentrations. Utilizing response surface methodology, correlations between corrosion factors and two crucial response variables, passive film breakdown potential and protection potential, are established. Cyclic potentiodynamic polarization tests and advanced analytical techniques provide detailed insights into the material's behavior. This research goes beyond, deriving an equation through response surface methodology that elucidates the relationship between the factors and breakdown potential. HS- weakens the passive film and reduces the pitting corrosion resistance of the stainless steel. However, this study highlights the inhibitory effect of HS- on pitting corrosion when Cl- concentrations are below 0.001 M and at equivalent concentrations of HS-. Under these conditions, immediate re-passivation occurs from the destroyed passive film to metal sulfides such as FeS2, MoS2, and MoS3. As a result, no hysteresis loop occurs in the cyclic polarization curve in these conditions. This research contributes to the understanding of Type 316 stainless-steel corrosion behavior, offering implications for the disposal of radioactive waste in geological repositories.
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The automobile industry commonly uses cyclic corrosion tests (CCTs) to evaluate the durability of materials. However, the extended evaluation period required by CCTs can pose challenges in this fast-paced industry. To address this issue, a new approach that combines a CCT with an electrochemically accelerated corrosion test has been explored, to shorten the evaluation period. This method involves the formation of a corrosion product layer through a CCT, which leads to localized corrosion, followed by applying an electrochemically accelerated corrosion test using an agar gel electrolyte to preserve the corrosion product layer as much as possible. The results indicate that this approach can achieve comparable localized corrosion resistance, with similar localized corrosion area ratios and maximum localized corrosion depths to those obtained through a conventional CCT in half the time.
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BACKGROUND: Recently, the American Diabetes Association (ADA) has included glycated hemoglobin A1(c) (A1C) level as a component of diagnostic criteria of 'diabetes' or 'increased risk for diabetes'. This study was conducted to examine the prevalence of and risk factors for 'elevated A1C' (≥5.7%) in women with polycystic ovary syndrome (PCOS). METHODS: A1C was measured using an immunoturbidimetric assay, and was evaluated in 154 patients with PCOS and 469 age-matched controls (match ratio of 1-3). All subjects were categorized by BMI (non-obese <25 kg/m(2) and obese ≥25 kg/m(2)), and the prevalence of elevated A1C was also analyzed according to BMI. RESULTS: One-third (31.2%) of the patients with PCOS had elevated A1C. The prevalence of elevated A1C (≥5.7%) was similar in obese women with PCOS and obese controls (23.5 and 20.0%, respectively, P= 1.0) but non-obese women with PCOS (mean age 29.8 ± 5.3 years) had a higher prevalence of elevated A1C than non-obese controls (31.2 versus 6.6%, respectively, P< 0.001). Logistic regression analysis of all subjects showed that the odds that a woman has elevated A1C was 6.7 times higher if she has PCOS (adjusted odds ratio 6.67, 95% confidence interval 3.50-12.70). CONCLUSIONS: The high prevalence of elevated A1C in non-obese patients with PCOS and an increased risk of elevated A1C associated with PCOS suggest that PCOS itself may be associated with abnormal A1C status. Assessing A1C level in young, non-obese patients with PCOS may be a useful new approach to screening for diabetes.
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Hemoglobina Glucada/metabolismo , Síndrome del Ovario Poliquístico/metabolismo , Adolescente , Adulto , Glucemia , Estudios de Casos y Controles , Complicaciones de la Diabetes/diagnóstico , Complicaciones de la Diabetes/metabolismo , Diabetes Mellitus/diagnóstico , Diabetes Mellitus/metabolismo , Femenino , Humanos , Síndrome del Ovario Poliquístico/complicaciones , Prevalencia , Factores de RiesgoRESUMEN
AIMS: The aim of the present study was to identify the fresh variables that influence the frozen-thawed embryo transfer (FET) outcome using sibling two pronuclei (2PN) embryos in women with polycystic ovary syndrome (PCOS) and non-PCOS women. MATERIAL & METHODS: Fifty-five FET cycles were performed using sibling embryos randomly cryopreserved at 2PN states and basal/cycle characteristics of fresh variables were compared between PCOS and non-PCOS groups according to the success in FET pregnancy: group A (pregnant PCOS); group B (not pregnant PCOS); group C (pregnant non-PCOS); group D (not pregnant non-PCOS). RESULTS: In PCOS patients, higher progesterone level on human chorionic gonadotropin (hCG) day was observed in group A than in group B (0.9 ± 0.0 vs. 0.5 ± 0.3, p = 0.004). In non-PCOS patients who achieved a pregnancy in the fresh cycle, a subsequent FET cycle using sibling 2PN embryos conferred a thirteen times increased chance of achieving pregnancy (OR 13.0; 95% CI, 2.3-74.1). Embryo quality and endometrial maturation were comparable between A and B or C and D. CONCLUSIONS: The success of the fresh embryo transfer (ET)was the most important predictor of pregnancy in FET cycles in the non-PCOS group. The relationship between serum progesterone on hCG day in the fresh cycle and the outcome of subsequent FET would benefit further evaluation in PCOS group.
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Criopreservación , Transferencia de Embrión , Infertilidad Femenina/terapia , Síndrome del Ovario Poliquístico/complicaciones , Adulto , Femenino , Fertilización In Vitro , Humanos , Infertilidad Femenina/etiología , Masculino , Embarazo , Índice de EmbarazoRESUMEN
OBJECTIVES: Since it has been suggested that intracytoplasmic sperm injection (ICSI) might impair the early development of embryos and twin pregnancies have physiologically different aspects from singleton pregnancies, we aimed to investigate the effect of ICSI on the human chrionic gonadotropin (hCG) levels in twin pregnancies. METHODS: A total of 220 clinical pregnancies which underwent controlled ovarian hyperstimulation and in vitro fertilization/ICSI were analyzed retrospectively. RESULTS: In twin pregnancies, the mean number of retrieved oocytes and estradiol (E2) levels on hCG day were significantly higher in ICSI group in spite of lower dose of gonadotropin. The hCG levels according to insemination method did not demonstrate any difference after adjustment for age of patient and partner, BMI, treatment regimens, serum E2 on hCG day, number of oocytes retrieved and date of sampling. CONCLUSIONS: The hCG values according to fertilization methods were not significantly different both in twin pregnancies with adjustment for confounders.
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Gonadotropina Coriónica/sangre , Embarazo Gemelar/sangre , Inyecciones de Esperma Intracitoplasmáticas , Adulto , Estudios de Cohortes , Transferencia de Embrión/métodos , Estradiol/sangre , Femenino , Edad Gestacional , Humanos , Masculino , Embarazo , Índice de Embarazo , Embarazo Gemelar/fisiología , Estudios Retrospectivos , Factores de TiempoRESUMEN
PURPOSE: To evaluate the relationship between endometriosis and polymorphisms in the genes encoding tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), TRAIL receptor (DR) and osteoprotegerin (OPG) and their serum levels in Korean women. METHODS: A case-control study was conducted with 138 women with endometriosis and 214 women without endometriosis in academic medical center. TRAIL c.49G>A, c.592A>G, c.615A>G, and c.662T>C; DR4 c.626G>C and c.1322A>G; DR5 c.95C>T, c.200C>T, and c.72T>G; OPG -245T>G, c.9C>G, c.788A>C, and c.9938G>T polymorphisms were investigated and circulating levels of TRAIL and OPG were measured. RESULTS: The TRAIL c.49G>A, c.615A>G, and c.662T>C; the DR4 c.626G>C; the DR5 c.72T>G; the OPG c.788A>C and c.9938G>T polymorphisms were not observed. The genotype distributions and allele frequencies of single or combined polymorphisms of TRAIL, DR4, DR5, and OPG measured in women with endometriosis were not different from those in women without endometriosis, regardless of endometriosis stage. Serum TRAIL and OPG levels were significantly lower in women with endometriosis than in women without endometriosis, but these levels did not show differences between early and advanced endometriosis. CONCLUSIONS: Endometriosis is associated with circulating TRAIL and OPG levels in Korean women but not with the TRAIL, DR, and OPG polymorphisms.
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Endometriosis/sangre , Endometriosis/genética , Osteoprotegerina/genética , Receptores del Ligando Inductor de Apoptosis Relacionado con TNF/genética , Ligando Inductor de Apoptosis Relacionado con TNF/genética , Adulto , Pueblo Asiatico/genética , Estudios de Casos y Controles , Femenino , Frecuencia de los Genes , Genotipo , Humanos , Osteoprotegerina/sangre , Polimorfismo de Nucleótido Simple , Receptores del Ligando Inductor de Apoptosis Relacionado con TNF/sangre , República de Corea , Ligando Inductor de Apoptosis Relacionado con TNF/sangre , Adulto JovenRESUMEN
In this work, a cerium/tetraethylenepentamine dithiocarbamate complex was synthesized and evaluated for the corrosion inhibition capability on an AA2024-T3 Al alloy in a 3.5% NaCl medium. The synthesized compounds were characterized via spectroscopic techniques. The corrosion inhibition behaviour of the complex was elucidated by electrochemical measurements and surface analysis techniques. Based on electrochemical test results, the corrosion inhibition efficiency of the complex increases with the immersion time of aluminium alloy in the test solution. The corrosion inhibition reaches 96.80% when the aluminium is immersed in a 3.5% NaCl solution containing a corrosion inhibitor for 120 h. The potentiodynamic polarization test results show that the complex acts as a mixed-type corrosion inhibitor and the passive range is widened. The surface analysis methods reveal that the corrosion inhibition ability of the complex originated from the formation of a protective layer on the Al surface. This film is created from the physisorption and chemisorption of cerium ions and organic parts simultaneously released from the complex molecules.
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Soil corrosion is always a critical concern to corrosion engineering because of the economic influence of soil infrastructures as has been and has recently been the focus of spent nuclear fuel canisters. Besides corrosion protection, the corrosion prediction of the canister is also important. Advanced knowledge of the corrosion rate of spent nuclear fuel canister material in a particular environment can be extremely helpful in choosing the best protection method. Applying machine learning (ML) to corrosion rate prediction solves all the challenges because of the number of variables affecting soil corrosion. In this study, several algorithms of ML, including series individual, boosting, bagging artificial neural network (ANN), series individual, boosting, bagging Chi-squared automatic interaction detection (CHAID) tree decision, linear regression (LR) and an ensemble learning (EL) merge the best option that collects from 3 algorithm methods above. From the performance of each model to find the model with the highest accuracy is the ensemble stacking method. Mean absolute error performance matrices are shown in Fig. 15. Besides applying ML, the significance of the input variables was also determined through sensitivity analysis using the feature importance criterion, and the carbon steel corrosion rate is the most sensitive to temperature and chloride.
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This study investigated the hydrogen embrittlement (HE) characteristics of advanced high-strength steels (AHSSs). Two different types of AHSSs with a tensile strength of 1.2 GPa were investigated. Slow strain rate tests (SSRTs) were performed under various applied potentials (Eapp) to identify the mechanism with the greatest effect on the embrittlement of the specimens. The SSRT results revealed that, as the Eapp increased, the elongation tended to increase, even when a potential exceeding the corrosion potential was applied. Both types of AHSSs exhibited embrittled fracture behavior that was dominated by HE. The fractured SSRT specimens were subjected to a thermal desorption spectroscopy analysis, revealing that diffusible hydrogen was trapped mainly at the grain boundaries and dislocations (i.e., reversible hydrogen-trapping sites). The micro-analysis results revealed that the poor HE resistance of the specimens was attributed to the more reversible hydrogen-trapping sites.