Pub Date : 2024-07-03Epub Date: 2024-06-14DOI: 10.1021/jacs.4c04716
Morgan S Young, Anne M LaPointe, Samantha N MacMillan, Geoffrey W Coates
Herein, we report that (S,S)-prophenolMg2(μ-OnBu)(THF)2 ((S,S)-1, prophenol = (S,S)-2,6-bis[2-(hydroxydiphenylmethyl)pyrrolidin-1-ylmethyl]-4-methylphenol) is a highly enantioselective (kR/kS = 140) precatalyst for ring-opening polymerization of rac-β-butyrolactone (β-BL) to isotactic poly(3-hydroxybutyrate) (i-PHB), a high performance, biodegradable polyester. Precatalyst (S,S)-1 polymerizes (R)-β-BL with an inversion of stereochemistry to (S)-PHB with a m% (percentage of adjacent linkages with a meso configuration) of 98% at 41% conversion and Tm of 165 °C under a variety of conditions. Complex (S,S)-1 demonstrates unique polymerization kinetics, as it does not polymerize the preferred enantiomer, (R)-β-BL, alone. Mechanistic studies revealed that (S)-β-BL is needed to convert (S,S)-1 into the active enantioselective polymerization catalyst. To the best of our knowledge, (S,S)-1 produces i-PHB with the highest degree of isotacticity observed from a polymerization of rac-β-BL. This study informs the design and understanding of future enantioselective and earth-abundant metal catalysts for ring-opening polymerization of β-lactones.
{"title":"Highly Enantioselective Polymerization of β-Butyrolactone by a Bimetallic Magnesium Catalyst: An Interdependent Relationship Between Favored and Unfavored Enantiomers.","authors":"Morgan S Young, Anne M LaPointe, Samantha N MacMillan, Geoffrey W Coates","doi":"10.1021/jacs.4c04716","DOIUrl":"10.1021/jacs.4c04716","url":null,"abstract":"<p><p>Herein, we report that (<i>S</i>,<i>S</i>)-prophenolMg<sub>2</sub>(μ-O<sup><i>n</i></sup>Bu)(THF)<sub>2</sub> ((<i>S</i>,<i>S</i>)-<b>1</b>, prophenol = (<i>S</i>,<i>S</i>)-2,6-bis[2-(hydroxydiphenylmethyl)pyrrolidin-1-ylmethyl]-4-methylphenol) is a highly enantioselective (<i>k</i><sub>R</sub>/<i>k</i><sub>S</sub> = 140) precatalyst for ring-opening polymerization of <i>rac</i>-β-butyrolactone (β-BL) to isotactic poly(3-hydroxybutyrate) (<i>i</i>-PHB), a high performance, biodegradable polyester. Precatalyst (<i>S</i>,<i>S</i>)-<b>1</b> polymerizes (<i>R</i>)-β-BL with an inversion of stereochemistry to (<i>S</i>)<i>-</i>PHB with a <i>m</i>% (percentage of adjacent linkages with a <i>meso</i> configuration) of 98% at 41% conversion and <i>T</i><sub>m</sub> of 165 °C under a variety of conditions. Complex (<i>S</i>,<i>S</i>)-<b>1</b> demonstrates unique polymerization kinetics, as it does not polymerize the preferred enantiomer, (<i>R</i>)-β-BL, alone. Mechanistic studies revealed that (<i>S</i>)-β-BL is needed to convert (<i>S</i>,<i>S</i>)-<b>1</b> into the active enantioselective polymerization catalyst. To the best of our knowledge, (<i>S</i>,<i>S</i>)-<b>1</b> produces <i>i</i>-PHB with the highest degree of isotacticity observed from a polymerization of <i>rac</i>-β-BL. This study informs the design and understanding of future enantioselective and earth-abundant metal catalysts for ring-opening polymerization of β-lactones.</p>","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":null,"pages":null},"PeriodicalIF":14.4,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141316077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03Epub Date: 2024-06-14DOI: 10.1021/acschemneuro.4c00204
Sébastien Goutal, Thi Tran, Claire Leroy, Nadine Benhamouda, Sarah Leterrier, Wadad Saba, Bruno Lafont, Éric Tartour, Marie Roelens, Nicolas Tournier
Neuroimaging biomarkers are needed to investigate the impact of smoking withdrawal on brain function. NFL-101 is a denicotinized aqueous extract of tobacco leaves currently investigated as an immune-based smoking cessation therapy in humans. However, the immune response to NFL-101 and its ability to induce significant changes in brain function remain to be demonstrated. Brain glucose metabolism was investigated using [18F]fluoro-deoxy-glucose ([18F]FDG) PET imaging in a mouse model of cigarette smoke exposure (CSE, 4-week whole-body inhalation, twice daily). Compared with control animals, the relative uptake of [18F]FDG in CSE mice was decreased in the thalamus and brain stem (p < 0.001, n = 14 per group) and increased in the hippocampus, cortex, cerebellum, and olfactory bulb (p < 0.001). NFL-101 induced a humoral immune response (specific IgGs) in mice and activated human natural-killer lymphocytes in vitro. In CSE mice, but not in control mice, single-dose NFL-101 significantly increased [18F]FDG uptake in the thalamus (p < 0.01), thus restoring normal brain glucose metabolism after 2-day withdrawal in this nicotinic receptor-rich region. In tobacco research, [18F]FDG PET imaging provides a quantitative method to evaluate changes in the brain function associated with the withdrawal phase. This method also showed the CNS effects of NFL-101, with translational perspectives for future clinical evaluation in smokers.
{"title":"Brain Glucose Metabolism as a Readout of the Central Nervous System Impact of Cigarette Smoke Exposure and Withdrawal and the Effects of NFL-101, as an Immune-Based Drug Candidate for Smoking Cessation Therapy.","authors":"Sébastien Goutal, Thi Tran, Claire Leroy, Nadine Benhamouda, Sarah Leterrier, Wadad Saba, Bruno Lafont, Éric Tartour, Marie Roelens, Nicolas Tournier","doi":"10.1021/acschemneuro.4c00204","DOIUrl":"10.1021/acschemneuro.4c00204","url":null,"abstract":"<p><p>Neuroimaging biomarkers are needed to investigate the impact of smoking withdrawal on brain function. NFL-101 is a denicotinized aqueous extract of tobacco leaves currently investigated as an immune-based smoking cessation therapy in humans. However, the immune response to NFL-101 and its ability to induce significant changes in brain function remain to be demonstrated. Brain glucose metabolism was investigated using [<sup>18</sup>F]fluoro-deoxy-glucose ([<sup>18</sup>F]FDG) PET imaging in a mouse model of cigarette smoke exposure (CSE, 4-week whole-body inhalation, twice daily). Compared with control animals, the relative uptake of [<sup>18</sup>F]FDG in CSE mice was decreased in the thalamus and brain stem (<i>p</i> < 0.001, <i>n</i> = 14 per group) and increased in the hippocampus, cortex, cerebellum, and olfactory bulb (<i>p</i> < 0.001). NFL-101 induced a humoral immune response (specific IgGs) in mice and activated human natural-killer lymphocytes in vitro. In CSE mice, but not in control mice, single-dose NFL-101 significantly increased [<sup>18</sup>F]FDG uptake in the thalamus (<i>p</i> < 0.01), thus restoring normal brain glucose metabolism after 2-day withdrawal in this nicotinic receptor-rich region. In tobacco research, [<sup>18</sup>F]FDG PET imaging provides a quantitative method to evaluate changes in the brain function associated with the withdrawal phase. This method also showed the CNS effects of NFL-101, with translational perspectives for future clinical evaluation in smokers.</p>","PeriodicalId":13,"journal":{"name":"ACS Chemical Neuroscience","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141320079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Trimethylamine N-oxide (TMAO), a characteristic nonprotein nitrogen compound, is widely present in seafood, which exhibits osmoregulatory effects for marine organisms in vivo and plays an important role in aquaculture and aquatic product preservation. However, much attention has been focused on the negative effect of TMAO since it has recently emerged as a putative promoter of chronic diseases. To get full knowledge and maximize our ability to balance the positive and negative aspects of TMAO, in this review, we comprehensively discuss the TMAO in aquatic products from the aspects of physiological functions for marine organisms, flavor, quality, the conversion of precursors, the influences on human health, and the seafood ingredients interaction consideration. Though the circulating TMAO level is inevitably enhanced after seafood consumption, dietary seafood still exhibits beneficial health effects and may provide nutraceuticals to balance the possible adverse effects of TMAO.
{"title":"Trimethylamine N-Oxide in Aquatic Foods.","authors":"Xiaoyue Li, Chengcheng Wang, Teruyoshi Yanagita, Changhu Xue, Tiantian Zhang, Yuming Wang","doi":"10.1021/acs.jafc.4c01974","DOIUrl":"10.1021/acs.jafc.4c01974","url":null,"abstract":"<p><p>Trimethylamine N-oxide (TMAO), a characteristic nonprotein nitrogen compound, is widely present in seafood, which exhibits osmoregulatory effects for marine organisms <i>in vivo</i> and plays an important role in aquaculture and aquatic product preservation. However, much attention has been focused on the negative effect of TMAO since it has recently emerged as a putative promoter of chronic diseases. To get full knowledge and maximize our ability to balance the positive and negative aspects of TMAO, in this review, we comprehensively discuss the TMAO in aquatic products from the aspects of physiological functions for marine organisms, flavor, quality, the conversion of precursors, the influences on human health, and the seafood ingredients interaction consideration. Though the circulating TMAO level is inevitably enhanced after seafood consumption, dietary seafood still exhibits beneficial health effects and may provide nutraceuticals to balance the possible adverse effects of TMAO.</p>","PeriodicalId":41,"journal":{"name":"Journal of Agricultural and Food Chemistry","volume":null,"pages":null},"PeriodicalIF":5.7,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03Epub Date: 2024-06-18DOI: 10.1021/acs.nanolett.4c01508
Yang-Hao Chan, Mit H Naik, Jonah B Haber, Jeffrey B Neaton, Steven G Louie, Diana Y Qiu, Felipe H da Jornada
Despite the weak, van der Waals interlayer coupling, photoinduced charge transfer vertically across atomically thin interfaces can occur within surprisingly fast, sub-50 fs time scales. An early theoretical understanding of charge transfer is based on a noninteracting picture, neglecting excitonic effects that dominate optical properties of such materials. We employ an ab initio many-body perturbation theory approach, which explicitly accounts for the excitons and phonons in the heterostructure. Our large-scale first-principles calculations directly probe the role of exciton-phonon coupling in the charge dynamics of the WS2/MoS2 heterobilayer. We find that the exciton-phonon interaction induced relaxation time of photoexcited excitons at the K valley of MoS2 and WS2 is 67 and 15 fs at 300 K, respectively, which sets a lower bound to the intralayer-to-interlayer exciton transfer time and is consistent with experiment reports. We further show that electron-hole correlations facilitate novel transfer pathways that are otherwise inaccessible to noninteracting electrons and holes.
尽管范德瓦耳斯层间耦合很弱,但光诱导电荷垂直穿过原子薄界面的传输速度却快得惊人,可达 50 fs 以下。对电荷转移的早期理论理解是基于非相互作用的图景,忽略了主导此类材料光学特性的激子效应。我们采用了一种 ab initio 多体扰动理论方法,该方法明确考虑了异质结构中的激子和声子。我们的大规模第一性原理计算直接探究了激子-声子耦合在 WS2/MoS2 异质层电荷动力学中的作用。我们发现,在 300 K 时,MoS2 和 WS2 K 谷光激发激子的弛豫时间分别为 67 fs 和 15 fs,这为层内到层间的激子转移时间设定了下限,并与实验报告一致。我们进一步证明,电子-空穴关联促进了新的转移途径,否则非相互作用的电子和空穴是无法进入这些途径的。
{"title":"Exciton-Phonon Coupling Induces a New Pathway for Ultrafast Intralayer-to-Interlayer Exciton Transition and Interlayer Charge Transfer in WS<sub>2</sub>-MoS<sub>2</sub> Heterostructure: A First-Principles Study.","authors":"Yang-Hao Chan, Mit H Naik, Jonah B Haber, Jeffrey B Neaton, Steven G Louie, Diana Y Qiu, Felipe H da Jornada","doi":"10.1021/acs.nanolett.4c01508","DOIUrl":"10.1021/acs.nanolett.4c01508","url":null,"abstract":"<p><p>Despite the weak, van der Waals interlayer coupling, photoinduced charge transfer vertically across atomically thin interfaces can occur within surprisingly fast, sub-50 fs time scales. An early theoretical understanding of charge transfer is based on a noninteracting picture, neglecting excitonic effects that dominate optical properties of such materials. We employ an <i>ab initio</i> many-body perturbation theory approach, which explicitly accounts for the excitons and phonons in the heterostructure. Our large-scale first-principles calculations directly probe the role of exciton-phonon coupling in the charge dynamics of the WS<sub>2</sub>/MoS<sub>2</sub> heterobilayer. We find that the exciton-phonon interaction induced relaxation time of photoexcited excitons at the <i>K</i> valley of MoS<sub>2</sub> and WS<sub>2</sub> is 67 and 15 fs at 300 K, respectively, which sets a lower bound to the intralayer-to-interlayer exciton transfer time and is consistent with experiment reports. We further show that electron-hole correlations facilitate novel transfer pathways that are otherwise inaccessible to noninteracting electrons and holes.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":9.6,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03Epub Date: 2024-06-17DOI: 10.1021/acs.nanolett.3c04180
Abhishek Kumar, Jonas Müller, Sylvain Pelloquin, Aurélie Lecestre, Guilhem Larrieu
Vertical gate-all-around (V-GAA) represents the ultimate configuration in the forthcoming transistor industry, but it still encounters challenges in the semiconductor community. This paper introduces, for the first time, a dual-input logic gate circuit achieved using 3D vertical transistors with nanoscale sub-20-nm GAA, employing a novel technique for creating contacts and patterning metallic lines at the bottom level without the conventional lift-off process. This involves a two-step oxidation process: patterning the first field oxide to form bottom metal lines and then creating the gate oxide layer on nanowires (NWs), followed by selective removal from the top and bottom of the nanostructures. VGAA-NW transistors, fabricated using the lift-off-free approach, exhibit improved yield and reduced access resistance, leading to an enhanced drive current while maintaining good immunity against short-channel effects. Finally, elementary two-input logic gates within a single cell, using VNW transistors, demonstrate novel possibilities in advanced logic circuitry design and routing options in 3D.
{"title":"Logic Gates Based on 3D Vertical Junctionless Gate-All-Around Transistors with Reliable Multilevel Contact Engineering.","authors":"Abhishek Kumar, Jonas Müller, Sylvain Pelloquin, Aurélie Lecestre, Guilhem Larrieu","doi":"10.1021/acs.nanolett.3c04180","DOIUrl":"10.1021/acs.nanolett.3c04180","url":null,"abstract":"<p><p>Vertical gate-all-around (V-GAA) represents the ultimate configuration in the forthcoming transistor industry, but it still encounters challenges in the semiconductor community. This paper introduces, for the first time, a dual-input logic gate circuit achieved using 3D vertical transistors with nanoscale sub-20-nm GAA, employing a novel technique for creating contacts and patterning metallic lines at the bottom level without the conventional lift-off process. This involves a two-step oxidation process: patterning the first field oxide to form bottom metal lines and then creating the gate oxide layer on nanowires (NWs), followed by selective removal from the top and bottom of the nanostructures. VGAA-NW transistors, fabricated using the lift-off-free approach, exhibit improved yield and reduced access resistance, leading to an enhanced drive current while maintaining good immunity against short-channel effects. Finally, elementary two-input logic gates within a single cell, using VNW transistors, demonstrate novel possibilities in advanced logic circuitry design and routing options in 3D.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":9.6,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The unique "Iron Addiction" feature of cancer stem cells (CSCs) with tumorigenicity and plasticity generally contributes to the tumor recurrence and metastasis after a lumpectomy. Herein, a novel "Ferroptosis Amplification" strategy is developed based on integrating gallic acid-modified FeOOH (GFP) and gallocyanine into Pluronic F-127 (F127) and carboxylated chitosan (CC)-based hydrogel for CSCs eradication. This "Ferroptosis Amplifier" hydrogel is thermally sensitive and achieves rapid gelation at the postsurgical wound in a breast tumor model. Specifically, gallocyanine, as the Dickkopf-1 (DKK1) inhibitor, can decrease the expression of SLC7A11 and GPX4 and synergistically induce ferroptosis of CSCs with GFP. Encouragingly, it is found that this combination suppresses the migratory and invasive capability of cancer cells via the downregulation of matrix metalloproteinase 7 (MMP7). The in vivo results further confirm that this "Ferroptosis Amplification" strategy is efficient in preventing tumor relapse and lung metastasis, manifesting an effective and promising postsurgical treatment for breast cancer.
{"title":"A \"Ferroptosis-Amplifier\" Hydrogel for Eliminating Refractory Cancer Stem Cells Post-lumpectomy.","authors":"Yutong Zhu, Xi Deng, Zideng Dai, Qing Liu, Yichen Kuang, Tianzhi Liu, Hangrong Chen","doi":"10.1021/acs.nanolett.4c02192","DOIUrl":"10.1021/acs.nanolett.4c02192","url":null,"abstract":"<p><p>The unique \"Iron Addiction\" feature of cancer stem cells (CSCs) with tumorigenicity and plasticity generally contributes to the tumor recurrence and metastasis after a lumpectomy. Herein, a novel \"Ferroptosis Amplification\" strategy is developed based on integrating gallic acid-modified FeOOH (GFP) and gallocyanine into Pluronic F-127 (F127) and carboxylated chitosan (CC)-based hydrogel for CSCs eradication. This \"Ferroptosis Amplifier\" hydrogel is thermally sensitive and achieves rapid gelation at the postsurgical wound in a breast tumor model. Specifically, gallocyanine, as the Dickkopf-1 (DKK1) inhibitor, can decrease the expression of SLC7A11 and GPX4 and synergistically induce ferroptosis of CSCs with GFP. Encouragingly, it is found that this combination suppresses the migratory and invasive capability of cancer cells <i>via</i> the downregulation of matrix metalloproteinase 7 (MMP7). The <i>in vivo</i> results further confirm that this \"Ferroptosis Amplification\" strategy is efficient in preventing tumor relapse and lung metastasis, manifesting an effective and promising postsurgical treatment for breast cancer.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":9.6,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The physical properties of nanoscale cell-extracellular matrix (ECM) ligands profoundly impact biological processes, such as adhesion, motility, and differentiation. While the mechanoresponse of cells to static ligands is well-studied, the effect of dynamic ligand presentation with "adaptive" properties on cell mechanotransduction remains less understood. Utilizing a controllable diffusible ligand interface, we demonstrated that cells on surfaces with rapid ligand mobility could recruit ligands through activating integrin α5β1, leading to faster focal adhesion growth and spreading at the early adhesion stage. By leveraging UV-light-sensitive anchor molecules to trigger a "dynamic to static" transformation of ligands, we sequentially activated α5β1 and αvβ3 integrins, significantly promoting osteogenic differentiation of mesenchymal stem cells. This study illustrates how manipulating molecular dynamics can directly influence stem cell fate, suggesting the potential of "sequentially" controlled mobile surfaces as adaptable platforms for engineering smart biomaterial coatings.
{"title":"Dynamic Regulation of Cell Mechanotransduction through Sequentially Controlled Mobile Surfaces.","authors":"Wenyan Xie, Linjie Ma, Peng Wang, Xiaojing Liu, Di Wu, Yuan Lin, Zhiqin Chu, Yong Hou, Qiang Wei","doi":"10.1021/acs.nanolett.4c01371","DOIUrl":"10.1021/acs.nanolett.4c01371","url":null,"abstract":"<p><p>The physical properties of nanoscale cell-extracellular matrix (ECM) ligands profoundly impact biological processes, such as adhesion, motility, and differentiation. While the mechanoresponse of cells to static ligands is well-studied, the effect of dynamic ligand presentation with \"adaptive\" properties on cell mechanotransduction remains less understood. Utilizing a controllable diffusible ligand interface, we demonstrated that cells on surfaces with rapid ligand mobility could recruit ligands through activating integrin α5β1, leading to faster focal adhesion growth and spreading at the early adhesion stage. By leveraging UV-light-sensitive anchor molecules to trigger a \"dynamic to static\" transformation of ligands, we sequentially activated α5β1 and αvβ3 integrins, significantly promoting osteogenic differentiation of mesenchymal stem cells. This study illustrates how manipulating molecular dynamics can directly influence stem cell fate, suggesting the potential of \"sequentially\" controlled mobile surfaces as adaptable platforms for engineering smart biomaterial coatings.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":9.6,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Developing highly efficient and carbon monoxide (CO)-tolerant platinum (Pt) catalysts for the formic acid oxidation reaction (FAOR) is vital for direct formic acid fuel cells (DFAFCs), yet it is challenging due to the high energy barrier of direct intermediates (HCOO* and COOH*) as well as the CO poisoning issues associated with Pt alloy catalysts. Here we present a versatile biphasic strategy by creating a hexagonal/cubic crystalline-phase-synergistic PtPb/C (h/c-PtPb/C) catalyst to tackle the aforementioned issues. Detailed investigations reveal that h/c-PtPb/C can simultaneously facilitate the adsorption of direct intermediates while inhibiting CO adsorption, thereby significantly improving the activation and CO spillover. As a result, h/c-PtPb/C showcases an outstanding FAOR activity of 8.1 A mgPt-1, which is 64.5 times higher than that of commercial Pt/C and significantly surpasses monophasic PtPb. Moreover, the h/c-PtPb/C-based membrane electrode assembly exhibits an exceptional peak power density of 258.7 mW cm-2 for practical DFAFC applications.
为甲酸氧化反应(FAOR)开发高效且耐一氧化碳(CO)的铂(Pt)催化剂对直接甲酸燃料电池(DFAFC)至关重要,但由于直接中间产物(HCOO* 和 COOH*)的高能垒以及与铂合金催化剂相关的 CO 中毒问题,开发这种催化剂具有挑战性。在此,我们通过创建六方/立方晶相协同 PtPb/C(h/c-PtPb/C)催化剂,提出了一种多功能双相策略,以解决上述问题。详细研究表明,h/c-PtPb/C 可在抑制 CO 吸附的同时促进直接中间产物的吸附,从而显著改善活化和 CO 溢出。因此,h/c-PtPb/C 的 FAOR 活性高达 8.1 A mgPt-1,是商用 Pt/C 的 64.5 倍,大大超过了单相 PtPb。此外,基于 h/c-PtPb/C 的膜电极组件的峰值功率密度高达 258.7 mW cm-2,非常适合实际的 DFAFC 应用。
{"title":"A Biphasic Strategy to Synergistically Accelerate Activation and CO Spillover in Formic Acid Oxidation Catalysis.","authors":"Changhong Zhan, Haoran Sun, Wei Yan, Jing Xia, Xiang-Min Meng, Tongtong Li, Lingzheng Bu, Qingyu Kong, Haixin Lin, Wei Liu, Xiaoqing Huang, Nanjun Chen","doi":"10.1021/acs.nanolett.4c02074","DOIUrl":"10.1021/acs.nanolett.4c02074","url":null,"abstract":"<p><p>Developing highly efficient and carbon monoxide (CO)-tolerant platinum (Pt) catalysts for the formic acid oxidation reaction (FAOR) is vital for direct formic acid fuel cells (DFAFCs), yet it is challenging due to the high energy barrier of direct intermediates (HCOO* and COOH*) as well as the CO poisoning issues associated with Pt alloy catalysts. Here we present a versatile biphasic strategy by creating a hexagonal/cubic crystalline-phase-synergistic PtPb/C (<i>h</i>/<i>c</i>-PtPb/C) catalyst to tackle the aforementioned issues. Detailed investigations reveal that <i>h</i>/<i>c</i>-PtPb/C can simultaneously facilitate the adsorption of direct intermediates while inhibiting CO adsorption, thereby significantly improving the activation and CO spillover. As a result, <i>h</i>/<i>c</i>-PtPb/C showcases an outstanding FAOR activity of 8.1 A mg<sub>Pt</sub><sup>-1</sup>, which is 64.5 times higher than that of commercial Pt/C and significantly surpasses monophasic PtPb. Moreover, the <i>h</i>/<i>c</i>-PtPb/C-based membrane electrode assembly exhibits an exceptional peak power density of 258.7 mW cm<sup>-2</sup> for practical DFAFC applications.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":9.6,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141425633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To simulate a topological neural network handling weak signals via stochastic resonance (SR), it is necessary to introduce an inherent nonlinearity into nanoscale devices. We use the self-assembly method to successfully fabricate a phase-change quantum-dot string (PCQDS) crossing Pd/Nb:AlNO/AlNO/Nb:AlNO/Pd multilayer. The inherent nonlinearity of phase change couples with electron tunneling so that PCQDS responds to a long signal sequence in a modulated output style, in which the pulse pattern evolves to that enveloped by two sets of periodic wave characterized by neural action potential. We establish an SR mode consisting of several two-state systems in which dissipative tunneling is coupled to environment. Size oscillations owing to NbO QDs adaptively adjust barriers and wells, such that tunneling can be periodically modulated by either asymmetric energy or local temperature. When the external periodic signals are applied, the system first follows the forcing frequency. Subsequently, certain PCQDs oscillate independently and consecutively to produce complicated frequency and amplitude modulations.
{"title":"Adaptive Signal Modulation Evolved by the Inherent Nonlinearity of Phase-Change Quantum-Dot String.","authors":"Qin Wan, Fei Zeng, Ziao Lu, Junwei Yu, Tongjin Chen, Feng Pan","doi":"10.1021/acs.nanolett.4c01786","DOIUrl":"10.1021/acs.nanolett.4c01786","url":null,"abstract":"<p><p>To simulate a topological neural network handling weak signals via stochastic resonance (SR), it is necessary to introduce an inherent nonlinearity into nanoscale devices. We use the self-assembly method to successfully fabricate a phase-change quantum-dot string (PCQDS) crossing Pd/Nb:AlNO/AlNO/Nb:AlNO/Pd multilayer. The inherent nonlinearity of phase change couples with electron tunneling so that PCQDS responds to a long signal sequence in a modulated output style, in which the pulse pattern evolves to that enveloped by two sets of periodic wave characterized by neural action potential. We establish an SR mode consisting of several two-state systems in which dissipative tunneling is coupled to environment. Size oscillations owing to NbO QDs adaptively adjust barriers and wells, such that tunneling can be periodically modulated by either asymmetric energy or local temperature. When the external periodic signals are applied, the system first follows the forcing frequency. Subsequently, certain PCQDs oscillate independently and consecutively to produce complicated frequency and amplitude modulations.</p>","PeriodicalId":53,"journal":{"name":"Nano Letters","volume":null,"pages":null},"PeriodicalIF":9.6,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141425634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03Epub Date: 2024-06-20DOI: 10.1021/jacs.4c03534
Yifan Liao, Baptiste Le Roi, Hang Zhang, Charles E Diesendruck, Joshua M Grolman
Mechanical forces play critical roles in a wide variety of biological processes and diseases, yet measuring them directly at the molecular level remains one of the main challenges of mechanobiology. Here, we show a strategy to "Dip-conjugate" biologically derived materials at the chemical level to mechanophores, force-responsive molecular entities, using Click-chemistry. Contrary to classical prepolymerization mechanophore incorporation, this new protocol leads to detectable mechanochromic response with as low as 5% strain, finally making mechanophores relevant for many biological processes that have previously been inaccessible. Our results demonstrate the ubiquity of the technique with activation in synthetic polymers, carbohydrates, and proteins under mechanical force, with alpaca wool fibers as a key example. These results push the limits for mechanophore use in far more types of polymeric materials in applications ranging from molecular-level force damage detection to direct and quantitative 3D force measurements in mechanobiology.
{"title":"Facile Mechanophore Integration in Heterogeneous Biologically Derived Materials via \"Dip-Conjugation\".","authors":"Yifan Liao, Baptiste Le Roi, Hang Zhang, Charles E Diesendruck, Joshua M Grolman","doi":"10.1021/jacs.4c03534","DOIUrl":"10.1021/jacs.4c03534","url":null,"abstract":"<p><p>Mechanical forces play critical roles in a wide variety of biological processes and diseases, yet measuring them directly at the molecular level remains one of the main challenges of mechanobiology. Here, we show a strategy to \"Dip-conjugate\" biologically derived materials at the chemical level to mechanophores, force-responsive molecular entities, using Click-chemistry. Contrary to classical prepolymerization mechanophore incorporation, this new protocol leads to detectable mechanochromic response with as low as 5% strain, finally making mechanophores relevant for many biological processes that have previously been inaccessible. Our results demonstrate the ubiquity of the technique with activation in synthetic polymers, carbohydrates, and proteins under mechanical force, with alpaca wool fibers as a key example. These results push the limits for mechanophore use in far more types of polymeric materials in applications ranging from molecular-level force damage detection to direct and quantitative 3D force measurements in mechanobiology.</p>","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":null,"pages":null},"PeriodicalIF":14.4,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141425662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}