Metal additive manufacturing(MAM)enables near-net shape production of components with minimized waste and excellent mechanical performance based on multi-scale microstructural heterogeneity.Espe-cially,the dislocation...Metal additive manufacturing(MAM)enables near-net shape production of components with minimized waste and excellent mechanical performance based on multi-scale microstructural heterogeneity.Espe-cially,the dislocation cell network that often bears elemental segregation or precipitation of a secondary phase contributes to enhancing the strength of additively manufactured materials.The cell boundaries can also act as active nucleation sites for the formation of precipitates under post-MAM heat treatment,as the chemical heterogeneity and profuse dislocations generate a driving force for precipitation.In this work,we subjected a Co_(18)Cr_(15)Fe_(50)Ni_(10)Mo_(6.5)C_(0.5)(at%)medium-entropy alloy fabricated by laser powder bed fusion(LPBF)to post-LPBF annealing at 900℃for 10 min.Microstructural investigation revealed that the cell boundaries of the as-built sample,which were decorated by Mo segregation,are replaced byμphase andM_(6)C typecarbide precipitatesduringannealingwhile thegrainstructureand sizeremain unaffected,indicating that the post-LPBF annealing delivered the proper amount of heat input to alter only the cell structure.The yield strength slightly decreased with annealing due to a reduction in the strengthening effect by the cell boundaries despite an increased precipitation strengthening effect.How-ever,the post-LPBF annealing improved the strain hardenability and the ultimate tensile strength was enhanced from∼1.02 to∼1.15 GPa owing to reinforced back stress hardening by the increased disloca-tion pile-up at the precipitates.Our results suggest that the cell structure with chemical heterogeneity can be successfully controlled by careful post-MAM heat treatment to tailor the mechanical performance,while also providing insight into alloy design for additive manufacturing.展开更多
Cobalt pentlandite(Co9S8)is a promising non-precious catalyst due to its superior oxygen reduction reaction activity and excellent stability.However,its oxygen reduction reaction catalytic activity has traditionally b...Cobalt pentlandite(Co9S8)is a promising non-precious catalyst due to its superior oxygen reduction reaction activity and excellent stability.However,its oxygen reduction reaction catalytic activity has traditionally been limited to the four-electron pathway because of strong*OOH intermediate adsorption.In this study,we synthesized electron-deficient Co9S8 nanocrystals with an increased number of Co^(3+)states compared to conventional Co9S8.This was achieved by incorporating a high density of surface ligands in small-sized Co9S8nanocrystals,which enabled the transition of the electrochemical reduction pathway from four-electron oxygen reduction reaction to two-electron oxygen reduction reaction by decreasing*OOH adsorption strength.As a result,the Co^(3+)-enriched Co9S8 nanocrystals exhibited a high onset potential of 0.64 V(vs RHE)for two-electron oxygen reduction reaction,achieving H_(2)O_(2) selectivity of 70-80%over the potential range from 0.05 to 0.6 V.Additionally,these nanocrystals demonstrated a stable H_(2)O_(2) electrosynthesis at a rate of459.12 mmol g^(-1) h^(-1) with a H_(2)O_(2) Faradaic efficiency over 90%under alkaline conditions.This study provides insights into nanoscale catalyst design for modulating electrochemical reactions.展开更多
AIM To investigate histologic abnormalities in the gastric smooth muscle of patients with diabetes mellitus(DM).METHODS Full-thickness gastric specimens were obtained from patients undergoing surgery for gastric cance...AIM To investigate histologic abnormalities in the gastric smooth muscle of patients with diabetes mellitus(DM).METHODS Full-thickness gastric specimens were obtained from patients undergoing surgery for gastric cancer. H&E stain and Masson's Trichrome stain were performed to assess the degree of fibrosis. Immunohistochemical staining using various antibodies was also performed [antibodies against protein gene product 9.5(PGP9.5), neuronal nitric oxide synthase(n NOS), vasoactive intestinal peptide(VIP), neurokinin-1(NK1) receptor, c-Kit, and platelet-derived growth factor receptor-alpha,(PDGFRα)]. Immunofluorescent staining and evaluation with confocal microscopy were also conducted.RESULTS Twenty-six controls and 35 diabetic patients(21 shortduration patients and 14 long-duration patients) were included. There were no significant differences in basic demographics between the two groups except in mean body mass index(BMI)(higher in the DM group). Proportions of moderate-to-severe intercellular fibrosis in the muscle layer were significantly higher in the DM group than in the control group(P < 0.01). On immunohistochemical staining, c-Kit- and PDGFRα-positive immunoreactivity were significantly decreased in the DM group compared with the control group(P < 0.05). There were no statistically significant differences in PGP9.5, n NOS, VIP, and neurokinin 1 expression. On immunofluorescent staining, cellularity of interstitial cells of Cajal(ICC) was observed to decrease with increasing duration of DM.CONCLUSION Our study suggests that increased intercellular fibrosis, loss of ICC, and loss of fibroblast-like cells are found in the smooth muscle of DM patients. These abnormalities may contribute to changes in gastric motor activity in patients with DM.展开更多
Epitaxially grown III-nitride alloys are tightly bonded materials with mixed covalent-ionic bonds.This tight bonding presents tremendous challenges in developing III-nitride membranes,even though semiconductor membran...Epitaxially grown III-nitride alloys are tightly bonded materials with mixed covalent-ionic bonds.This tight bonding presents tremendous challenges in developing III-nitride membranes,even though semiconductor membranes can provide numerous advantages by removing thick,inflexible,and costly substrates.Herein,cavities with various sizes were introduced by overgrowing target layers,such as undoped GaN and green LEDs,on nanoporous templates prepared by electrochemical etching of n-type GaN.The large primary interfacial toughness was effectively reduced according to the design of the cavity density,and the overgrown target layers were then conveniently exfoliated by engineering tensile-stressed Ni layers.The resulting III-nitride membranes maintained high crystal quality even after exfoliation due to the use of GaN-based nanoporous templates with the same lattice constant.The microcavity-assisted crack propagation process developed for the current III-nitride membranes forms a universal process for developing various kinds of large-scale and high-quality semiconductor membranes.展开更多
Biodiesel as a renewable alternative to conventional diesel is a growing topic of interest due to its potential environmental benefits.It is typically produced from oilseed crops such as soybean,rapeseed,palm oil,or a...Biodiesel as a renewable alternative to conventional diesel is a growing topic of interest due to its potential environmental benefits.It is typically produced from oilseed crops such as soybean,rapeseed,palm oil,or animal fats.However,its sustainability is debated,primarily because of the reliance on edible oil feedstocks and associated economic and environmental concerns.This study explores alternative,non-edible feedstocks,such as algae and jatropha,that do not compete with food production,offering increased sustainability.Despite their potential,these feedstocks are hindered by high production costs.To address these challenges,innovative approaches in feedstock assessment are imperative for ensuring the long-term viability of biodiesel as an alternative fuel.This review examines explicitly the application of deep learning techniques in selecting and evaluating biodiesel feedstocks.It focuses on their production processes and the chemical and physical properties that impact biodiesel quality.Our comprehensive analysis demonstrates that ANNs provide significant insights into the feedstock assessment process,emerging as a potent tool for identifying new correlations within complex datasets.By leveraging this capability,ANNs can significantly advance biodiesel research,producing more sustainable and efficient feedstock production.The study concludes by highlighting the substantial potential of ANN modeling in contributing to renewable energy strategies and expanding biodiesel research,underscoring its vital role in accelerating the development of biodiesel as a sustainable fuel alternative.展开更多
基金supported by the National Research Founda-tion of Korea(NRF)grant funded by the Korean government(MSIT)(Nos.2021R1A2C3006662 and RS-2023-00281246)supported by the Principal R&D project(contract no.PNK9950)of the Korean Institute of Materials Science(KIMS).
文摘Metal additive manufacturing(MAM)enables near-net shape production of components with minimized waste and excellent mechanical performance based on multi-scale microstructural heterogeneity.Espe-cially,the dislocation cell network that often bears elemental segregation or precipitation of a secondary phase contributes to enhancing the strength of additively manufactured materials.The cell boundaries can also act as active nucleation sites for the formation of precipitates under post-MAM heat treatment,as the chemical heterogeneity and profuse dislocations generate a driving force for precipitation.In this work,we subjected a Co_(18)Cr_(15)Fe_(50)Ni_(10)Mo_(6.5)C_(0.5)(at%)medium-entropy alloy fabricated by laser powder bed fusion(LPBF)to post-LPBF annealing at 900℃for 10 min.Microstructural investigation revealed that the cell boundaries of the as-built sample,which were decorated by Mo segregation,are replaced byμphase andM_(6)C typecarbide precipitatesduringannealingwhile thegrainstructureand sizeremain unaffected,indicating that the post-LPBF annealing delivered the proper amount of heat input to alter only the cell structure.The yield strength slightly decreased with annealing due to a reduction in the strengthening effect by the cell boundaries despite an increased precipitation strengthening effect.How-ever,the post-LPBF annealing improved the strain hardenability and the ultimate tensile strength was enhanced from∼1.02 to∼1.15 GPa owing to reinforced back stress hardening by the increased disloca-tion pile-up at the precipitates.Our results suggest that the cell structure with chemical heterogeneity can be successfully controlled by careful post-MAM heat treatment to tailor the mechanical performance,while also providing insight into alloy design for additive manufacturing.
基金supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)and the Ministry of Trade,Industry&Energy(MOTIE)of the Republic of Korea(no.20224000000020)supported by the MSIT(Ministry of Science and ICT),Korea,under the ICAN(ICT Challenge and Advanced Network of HRD)support program(IITP-2024-RS-2024-00437186)supervised by the IITP(Institute for Information&Communications Technology Planning&Evaluation)。
文摘Cobalt pentlandite(Co9S8)is a promising non-precious catalyst due to its superior oxygen reduction reaction activity and excellent stability.However,its oxygen reduction reaction catalytic activity has traditionally been limited to the four-electron pathway because of strong*OOH intermediate adsorption.In this study,we synthesized electron-deficient Co9S8 nanocrystals with an increased number of Co^(3+)states compared to conventional Co9S8.This was achieved by incorporating a high density of surface ligands in small-sized Co9S8nanocrystals,which enabled the transition of the electrochemical reduction pathway from four-electron oxygen reduction reaction to two-electron oxygen reduction reaction by decreasing*OOH adsorption strength.As a result,the Co^(3+)-enriched Co9S8 nanocrystals exhibited a high onset potential of 0.64 V(vs RHE)for two-electron oxygen reduction reaction,achieving H_(2)O_(2) selectivity of 70-80%over the potential range from 0.05 to 0.6 V.Additionally,these nanocrystals demonstrated a stable H_(2)O_(2) electrosynthesis at a rate of459.12 mmol g^(-1) h^(-1) with a H_(2)O_(2) Faradaic efficiency over 90%under alkaline conditions.This study provides insights into nanoscale catalyst design for modulating electrochemical reactions.
基金Supported by the National Research Foundation of Korea Grant funded by the Korean Government,No.2014R1A5A2010008
文摘AIM To investigate histologic abnormalities in the gastric smooth muscle of patients with diabetes mellitus(DM).METHODS Full-thickness gastric specimens were obtained from patients undergoing surgery for gastric cancer. H&E stain and Masson's Trichrome stain were performed to assess the degree of fibrosis. Immunohistochemical staining using various antibodies was also performed [antibodies against protein gene product 9.5(PGP9.5), neuronal nitric oxide synthase(n NOS), vasoactive intestinal peptide(VIP), neurokinin-1(NK1) receptor, c-Kit, and platelet-derived growth factor receptor-alpha,(PDGFRα)]. Immunofluorescent staining and evaluation with confocal microscopy were also conducted.RESULTS Twenty-six controls and 35 diabetic patients(21 shortduration patients and 14 long-duration patients) were included. There were no significant differences in basic demographics between the two groups except in mean body mass index(BMI)(higher in the DM group). Proportions of moderate-to-severe intercellular fibrosis in the muscle layer were significantly higher in the DM group than in the control group(P < 0.01). On immunohistochemical staining, c-Kit- and PDGFRα-positive immunoreactivity were significantly decreased in the DM group compared with the control group(P < 0.05). There were no statistically significant differences in PGP9.5, n NOS, VIP, and neurokinin 1 expression. On immunofluorescent staining, cellularity of interstitial cells of Cajal(ICC) was observed to decrease with increasing duration of DM.CONCLUSION Our study suggests that increased intercellular fibrosis, loss of ICC, and loss of fibroblast-like cells are found in the smooth muscle of DM patients. These abnormalities may contribute to changes in gastric motor activity in patients with DM.
基金The work was supported by King Abdullah University of Science and Technology(KAUST)baseline funding BAS/1/1614-01-01 and King Abdulaziz City for Science and Technology(Grant No.KACST TIC R2-FP-008)This work was also supported by Korea Photonics Technology Institute(Project No.193300029).
文摘Epitaxially grown III-nitride alloys are tightly bonded materials with mixed covalent-ionic bonds.This tight bonding presents tremendous challenges in developing III-nitride membranes,even though semiconductor membranes can provide numerous advantages by removing thick,inflexible,and costly substrates.Herein,cavities with various sizes were introduced by overgrowing target layers,such as undoped GaN and green LEDs,on nanoporous templates prepared by electrochemical etching of n-type GaN.The large primary interfacial toughness was effectively reduced according to the design of the cavity density,and the overgrown target layers were then conveniently exfoliated by engineering tensile-stressed Ni layers.The resulting III-nitride membranes maintained high crystal quality even after exfoliation due to the use of GaN-based nanoporous templates with the same lattice constant.The microcavity-assisted crack propagation process developed for the current III-nitride membranes forms a universal process for developing various kinds of large-scale and high-quality semiconductor membranes.
文摘Biodiesel as a renewable alternative to conventional diesel is a growing topic of interest due to its potential environmental benefits.It is typically produced from oilseed crops such as soybean,rapeseed,palm oil,or animal fats.However,its sustainability is debated,primarily because of the reliance on edible oil feedstocks and associated economic and environmental concerns.This study explores alternative,non-edible feedstocks,such as algae and jatropha,that do not compete with food production,offering increased sustainability.Despite their potential,these feedstocks are hindered by high production costs.To address these challenges,innovative approaches in feedstock assessment are imperative for ensuring the long-term viability of biodiesel as an alternative fuel.This review examines explicitly the application of deep learning techniques in selecting and evaluating biodiesel feedstocks.It focuses on their production processes and the chemical and physical properties that impact biodiesel quality.Our comprehensive analysis demonstrates that ANNs provide significant insights into the feedstock assessment process,emerging as a potent tool for identifying new correlations within complex datasets.By leveraging this capability,ANNs can significantly advance biodiesel research,producing more sustainable and efficient feedstock production.The study concludes by highlighting the substantial potential of ANN modeling in contributing to renewable energy strategies and expanding biodiesel research,underscoring its vital role in accelerating the development of biodiesel as a sustainable fuel alternative.
