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Global weirding at mass extinction horizons

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National Science Review 2024年第1期11卷 10-12页

作者： gregory j.Retallack Department of Earth Sciences University of Oregon

A strong motivation for studying mass extinctions is understanding how current climatic and biodiversity crises will affect creatures living on land such as ourselves. Perhaps the question is: how bad can it get? In that case, terrestrial Permian-Triassic mass extinctions are an irresistible worst-case scenario [1].

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一颗自由进动的磁星

科学通报 2024年第25期69卷 3675-3677页

作者：高勇 gregory Desvignes 邵立晶 Max Planck Institute for Gravitational Physics (Albert Einstein Institute) Max Planck Institute for Radio Astronomy 北京大学科维理天文与天体物理研究所中国科学院国家天文台

磁星是一类具有强磁场和长自转周期的年轻中子星.这些天体极其致密,半径约为12 km,但质量却可达太阳的1～2倍.在已知的30颗磁星中,只有少数会偶尔产生射电辐射.磁星转动时,射电束像灯塔一样扫过天空,天文学家正是从这些规律的脉冲信号... 详细信息

磁星是一类具有强磁场和长自转周期的年轻中子星.这些天体极其致密,半径约为12 km,但质量却可达太阳的1～2倍.在已知的30颗磁星中,只有少数会偶尔产生射电辐射.磁星转动时,射电束像灯塔一样扫过天空,天文学家正是从这些规律的脉冲信号中探索中子星的奥秘. 2018年末,磁星XTE j1810-197在经历了X射线爆发后再次产生射电辐射,结束了其长达十年的射电静默期.通过长时间、高频次的监测,我们在射电偏振信号中发现射电束相对于地球的倾角发生了显著变化,并且这种变化在几个月内逐渐消失[1].我们认为这种变化是由磁星的自由进动引起的,并提出了衰减的进动模型来解释这一观测现象.这一发现不仅帮助我们更深入地理解了磁星的内部结构和辐射几何,而且很可能排除了自由进动作为重复快速射电暴起源的理论模型.

关键词：射电辐射磁星中子星 X射线爆发脉冲信号强磁场理论模型高频次

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Integrins and their potential roles in mammalian pregnancy

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journal of Animal Science and Biotechnology 2024年第1期15卷 1-19页

作者： gregory A.johnson Robert C.Burghardt Fuller W.Bazer Heewon Seo joe W.Cain Department of Veterinary Integrative Biosciences School of Veterinary Medicine and Biomedical SciencesTexas A&M UniversityCollege StationTX 77843‑4459USA Department of Animal Science College of Agriculture and Life SciencesTexas A&M UniversityCollege StationTX 77843‑2471USA

Integrins are a highly complex family of receptors that, when expressed on the surface of cells, can mediate reciprocal cell-to-cell and cell-to-extracellular matrix(ECM) interactions leading to assembly of integrin adhesion complexes(IACs) that initiate many signaling functions both at the membrane and deeper within the cytoplasm to coordinate processes including cell adhesion, migration, proliferation, survival, differentiation, and metabolism. All metazoan organisms possess integrins, and it is generally agreed that integrins were associated with the evolution of multicellularity, being essential for the association of cells with their neighbors and surroundings, during embryonic development and many aspects of cellular and molecular biology. Integrins have important roles in many aspects of embryonic development, normal physiology, and disease processes with a multitude of functions discovered and elucidated for integrins that directly influence many areas of biology and medicine, including mammalian pregnancy, in particular implantation of the blastocyst to the uterine wall, subsequent placentation and conceptus(embryo/fetus and associated placental membranes) development. This review provides a succinct overview of integrin structure, ligand binding, and signaling followed with a concise overview of embryonic development, implantation, and early placentation in pigs, sheep, humans, and mice as an example for rodents. A brief timeline of the initial localization of integrin subunits to the uterine luminal epithelium(LE) and conceptus trophoblast is then presented, followed by sequential summaries of integrin expression and function during gestation in pigs, sheep, humans, and rodents. As appropriate for this journal, summaries of integrin expression and function during gestation in pigs and sheep are in depth, whereas summaries for humans and rodents are brief. Because similar models to those illustrated in Fig. 1, 2, 3, 4, 5 and 6 are present throughout the sc

关键词： Humans Implantation Integrins Pigs Pregnancy Rodents Sheep

Liver-gut axis in the regulation of iron homeostasis

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World journal of Gastroenterology 2007年第35期13卷 4737-4745页

作者： Deepak Darshan gregory j.anderson Iron Metabolism Laboratory The Queensland Institute of Medical ResearchBrisbaneAustralia

The human body requires about 1-2 mg of iron per day for its normal functioning, and dietary iron is the only source for this essential metal. Since humans do not possess a mechanism for the active excretion of iron, the amount of iron in the body is determined by the amount absorbed across the proximal small intestine and, consequently, intestinal iron absorption is a highly regulated process. In recent years, the liver has emerged as a central regulator of both iron absorption and iron release from other tissues. It achieves this by secreting a peptide hormone called hepcidin that acts on the small intestinal epithelium and other cells to limit iron delivery to the plasma. Hepcidin itself is regulated in response to various systemic stimuli including variations in body iron stores, the rate of erythropoiesis, inflammation and hypoxia, the same stimuli that have been known for many years to modulate iron absorption. This review will summarize recent findings on the role played by the liver and hepcidin in the regulation of body iron absorption.

关键词： Iron Homeostasis Intestinal iron absorption Liver Hepcidin

A functional tacrolimus-releasing nerve wrap for enhancing nerve regeneration following surgical nerve repair

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Neural Regeneration Research 2025年第1期20卷 291-304页

作者： Simeon C.Daeschler Katelyn j.W.So Konstantin Feinberg Marina Manoraj jenny Cheung jennifer Zhang Kaveh Mirmoeini jPaul Santerre Tessa Gordon gregory HBorschel SickKids Research Institute Neuroscience and Mental Health ProgramTorontoONCanada Institute of Biomaterials and Biomedical Engineering University of TorontoTorontoONCanada Indiana University School of Medicine IndianapolisINUSA Division of Plastic and Reconstructive Surgery the Hospital for Sick ChildrenTorontoONCanada Translational Biology and Engineering Program Ted Rogers Centre for Heart ResearchInstitute of Biomedical EngineeringFaculty of DentistryUniversity of TorontoTorontoONCanada

Axonal regeneration following surgical nerve repair is slow and often incomplete,resulting in poor functional recovery which sometimes contributes to lifelong ***,there are no FDA-approved therapies available to promote nerve *** accelerates axonal regeneration,but systemic side effects presently outweigh its potential benefits for peripheral nerve *** authors describe herein a biodegradable polyurethane-based drug delivery system for the sustained local release of tacrolimus at the nerve repair site,with suitable properties for scalable production and clinical application,aiming to promote nerve regeneration and functional recovery with minimal systemic drug *** is encapsulated into co-axially electrospun polycarbonate-urethane nanofibers to generate an implantable nerve wrap that releases therapeutic doses of bioactive tacrolimus over 31 *** and drug loading are adjustable for applications in small and large caliber nerves,and the wrap degrades within 120 days into biocompatible *** released from the nerve wrap promotes axon elongation in vitro and accelerates nerve regeneration and functional recovery in preclinical nerve repair models while off-target systemic drug exposure is reduced by 80%compared with systemic *** its surgical suitability and preclinical efficacy and safety,this system may provide a readily translatable approach to support axonal regeneration and recovery in patients undergoing nerve surgery.

关键词： biodegradable local drug delivery nerve injury nerve regeneration nerve wrap tacrolimus

室温和深冷轧制对纯Al再结晶{111}/{111}近奇异晶界的影响

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金属学报 2024年

作者：李振想王卫国 gregory S Rohrer 洪丽华陈松林燕周邦新福建理工大学材料科学与工程学院福建理工大学晶界工程研究所上海大学材料研究所 Department of Material Science and Engineering Carnegie Mellon University

{111}/{111}近奇异晶界比一般晶界更耐蚀，研究此类晶界的形成条件、影响因素和生成机制，设法调控此类晶界并提高其比例是改善相关铝合金晶界腐蚀性能的根本途径。为了解铝合金生成{111}/{111}近奇异晶界的本征行为，本工作选择高纯Al ... 详细信息

{111}/{111}近奇异晶界比一般晶界更耐蚀，研究此类晶界的形成条件、影响因素和生成机制，设法调控此类晶界并提高其比例是改善相关铝合金晶界腐蚀性能的根本途径。为了解铝合金生成{111}/{111}近奇异晶界的本征行为，本工作选择高纯Al (99.99%)为实验材料，首先经室温反复多向锻造和370℃再结晶退火获得晶粒尺寸均匀、平均晶粒尺寸约为20μm且晶粒取向随机分布的组织均匀化初始样品；再将初始样品分别在室温(25℃)和-196℃深冷进行厚度减缩量为80%的轧制变形，及370℃、30 min再结晶退火处理。采用EBSD和基于五参数分析的晶界界面匹配定量表征方法对两样品进行测试和分析。结果表明，经-196℃深冷轧制并再结晶的样品，其{111}/{111}近奇异晶界比例达到6.0%，相比室温轧制并再结晶的样品提升了120%。XRD、EBSD及硬度结果表明，经室温和-196℃深冷轧制的样品中均形成了较强的{011}形变织构；较比室温轧制，经-196℃深冷轧制的样品内残余压应力更大，晶粒碎化更严重、储能更高。在后续370℃退火过程中，经室温和-196℃深冷轧制的样品，其再结晶机制均以{011}取向生长为主；较比于室温轧制，经-196℃深冷轧制的样品可提供更大的晶界迁移驱动力，其样品再结晶组织的平均晶粒尺寸更大且{011}再结晶织构更强。统计结果表明，{011}取向晶粒与其他取向的晶粒毗连所形成的晶界中存在较高比例的{111}/{111}近奇异晶界；同时，为{011}取向晶粒与其相邻的且具有{011}漫散取向的晶粒间也形成较多的{111}/{111}近奇异晶界，这是导致经-196℃深冷轧制及再结晶的样品中{111}/{111}近奇异晶界比例较高的主要原因。

关键词：高纯Al 深冷轧制近奇异晶界晶界界面匹配择尤取向

The Emeishan large igneous province:A synthesis

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Geoscience Frontiers 2014年第3期5卷 369-394页

作者： j.gregory Shellnutt National Taiwan Normal University Department of Earth Science

The late Permian Emeishan large igneous province （EL1P） covers -0.3× 10-6 kmL of the western margin of the Yangtze Block and Tibetan Plateau with displaced, correlative units in northern Vietnam （Song Da zone）. The ELIP is of particular interest because it contains numerous world-class base metal deposits and is contemporaneous with the late Capitanian （-260 Ma） mass extinction. The flood basalts are the signature feature of the ELIP but there are also ultramafic and silicic volcanic rocks and layered mafic- ultramafic and silicic plutonic rocks exposed. The EL1P is divided into three nearly concentric zones （i.e. inner, middle and outer） which correspond to progressively thicker crust from the inner to the outer zone. The eruptive age of the ELIP is constrained by geological, paleomagnetic and geochronological evidence to an interval of 〈3 Ma. The presence of picritic rocks and thick piles of flood basalts testifies to high temperature thermal regime however there is uncertainty as to whether these magmas were derived from the subcontinental lithospheric mantle or sub-lithospheric mantle （i.e. asthenosphere or mantle plume） sources or both. The range of Sr （Isr ≈ 0.7040-0.7132）, Nd （ENd（t） ≈ -14 tO ＋8）, Pb （206-pb/204-pb1 ≈ 17.9-20.6） and Os （Yos ≈ -5 to ＋11） isotope values of the ultramafic and mafic rocks does not permit a conclusive answer to ultimate source origin of the primitive rocks but it is clear that some rocks were affected by crustal contamination and the presence of near-depleted isotope compo- sitions suggests that there is a sub-lithospheric mantle component in the system. The silicic rocks are derived by basaltic magmas/rocks through fractional crystallization or partial melting, crustal melting or by interactions between mafic and crustal melts. The formation of the Fe-Ti-V oxide-ore deposits is probably due to a combination of fractional crystallization of Ti-rich basalt and fluxing of C02-rich fluids whereas the Ni-Cu-（PGE） deposits are related

关键词： Late Permian Mantle plume Large igneous province Flood basalts Mineral deposits Uplift and doming

Potential of the neonicotinoid imidacloprid and the oxadiazine indoxacarb for controlling five coleopteran pests of stored grain

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Insect Science 2012年第1期19卷 96-101页

作者： gregory j. Daglish Manoj K. Nayak Agri-Science Queensland Department of Employment Economic Development and Innovation Brisbane Queensland Australia

The potential for using imidacloprid （a neonicotinoid） and indoxacarb （an oxadiazine） as grain protectants was investigated in bioassays against resistant strains of five stored grain beetles. The species investigated were Rhyzopertha dominica （E）（the lesser grain borer）, Sitophilus oryzae （L.）（the rice weevil）, Tribolium castaneum （Herbst）（the rust-red flour beetle）, Oryzaephilus surinamensis （L.）（the saw tooth flour beetle）, and Cryptolestesferrugineus （Stephens）（the fiat grain beetle）. Each of these species has developed resistance to one or more protectants, including organophosphorus insecticides, synthetic pyrethroids and the juvenile hormone analogue methoprene. Mortality and re- production after a 2-week exposure of adults to treated wheat depended on species, dose and insecticide. Imidacloprid had no effect on S. oryzae at any dose, but none of the other species produced any live progeny at 10 mg/kg. Indoxacarb had no effect on T. castaneum at any dose, but none of the other species produced any live progeny at 5 mg/kg. The results show that although both imidacloprid and indoxacarb can control at least four of the five key pests tested at doses comparable to those used for organophosphorus protectants, more potent neonicotinoid or oxadiazine insecticides would be needed than either of these to provide broad spectrum protection of stored grain .

关键词： beetles imidacloprid indoxacarb stored grain

Proteasome inhibition-induces endoplasmic reticulum dysfunction and cell death of human cholangiocarcinoma cells

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World journal of Gastroenterology 2007年第6期13卷 851-857页

作者： Yucel Ustundag Steven F Bronk gregory j Gores Mayo Clinic College of Medicine Rochester MN 55905 United States

AIM: To determine if proteasome inhibition induces apoptosis in human cholangiocarcinoma cells, and if so, to elucidate the cellular mechanisms. METHODS: Studies were performed in the human KMCH, KMBC, and Mz-ChA-1 cholangiocarcinoma, and normal rat cell lines. MG132, a peptide aldehyde, which inhibits the chymotrypsin-like activity of the proteaosome was employed for this study. Apoptosis was assessed morphologically by 4'-6-Diamidino-2-phenylindole (DAPI) nuclear staining and fluorescence microscopy. Mitochondrial membrane potential was examined using a fluorescent unquenching assay. Ultrastructural changes during cell death were examined using transmission electron microscopy (TEM). Caspase 3/7 activity was assessed using an enzymatic-based fluorescent assay. Cytosolic-free calcium concentrations were measured using Fura-2 and digitized fluorescent microscopy. RESULTS: MG132, a proteasome inhibitor, induced apoptosis in all the cholangiocarcinoma cell lines examined. In contrast, minimal cytotoxicity was observed in normal rat cholangiocytes. Apoptosis was time-and -concentration-dependent. There was no change in the mitochondrial membrane potential between treated and untreated cells. Ultrastructural examination by transmission electron microscopy displayed the classic features of apoptosis, but in addition, there was also dramatic vacuolization of the endoplasmic reticulum (ER). Unexpectedly, no increase in caspase 3/7 activity was observed in MG132 treated cells, nor did the pancaspase inhibitor, Q-VD-OPh prevent cell death. The protein synthesis inhibitor, cycloheximide, blocked apoptosis induced by proteosome inhibitor indicating that ER dysfunction was dependent upon the formation of new proteins. CONCLUSION: Proteosome inhibition induces ERdysfunction and caspase-independent cell death selectively in human cholangiocarcinoma cells. Proteasome inhibitors warrant evaluation as anticancer agents for the treatment of human cholangiocarcinoma.

关键词： MG132 Cholangiocarcinoma Proteosome Apoptosis Calcium