21 research outputs found
Nucleation of dislocations and their dynamics in layered oxide cathode materials during battery charging
Defects and their interactions in crystalline solids often underpin material
properties and functionality as they are decisive for stability, result in
enhanced diffusion, and act as a reservoir of vacancies. Recently, lithium-rich
layered oxides have emerged among the leading candidates for the
next-generation energy storage cathode material, delivering 50 % excess
capacity over commercially used compounds. Oxygen-redox reactions are believed
to be responsible for the excess capacity, however, voltage fading has
prevented commercialization of these new materials. Despite extensive research
the understanding of the mechanisms underpinning oxygen-redox reactions and
voltage fade remain incomplete. Here, using operando three-dimensional Bragg
coherent diffractive imaging, we directly observe nucleation of a mobile
dislocation network in nanoparticles of lithium-rich layered oxide material.
Surprisingly, we find that dislocations form more readily in the lithium-rich
layered oxide material as compared with a conventional layered oxide material,
suggesting a link between the defects and the anomalously high capacity in
lithium-rich layered oxides. The formation of a network of partial dislocations
dramatically alters the local lithium environment and contributes to the
voltage fade. Based on our findings we design and demonstrate a method to
recover the original high voltage functionality. Our findings reveal that the
voltage fade in lithium-rich layered oxides is reversible and call for new
paradigms for improved design of oxygen-redox active materials
BMP Signaling Modulates Hepcidin Expression in Zebrafish Embryos Independent of Hemojuvelin
Hemojuvelin (Hjv), a member of the repulsive-guidance molecule (RGM) family, upregulates transcription of the iron regulatory hormone hepcidin by activating the bone morphogenetic protein (BMP) signaling pathway in mammalian cells. Mammalian models have identified furin, neogenin, and matriptase-2 as modifiers of Hjv's function. Using the zebrafish model, we evaluated the effects of hjv and its interacting proteins on hepcidin expression during embryonic development. We found that hjv is strongly expressed in the notochord and somites of the zebrafish embryo and that morpholino knockdown of hjv impaired the development of these structures. Knockdown of hjv or other hjv-related genes, including zebrafish orthologs of furin or neogenin, however, failed to decrease hepcidin expression relative to liver size. In contrast, overexpression of bmp2b or knockdown of matriptase-2 enhanced the intensity and extent of hepcidin expression in zebrafish embryos, but this occurred in an hjv-independent manner. Furthermore, we demonstrated that zebrafish hjv can activate the human hepcidin promoter and enhance BMP responsive gene expression in vitro, but is expressed at low levels in the zebrafish embryonic liver. Taken together, these data support an alternative mechanism for hepcidin regulation during zebrafish embryonic development, which is independent of hjv
Promoting Patient Safety and Preventing Medical Error in Emergency Departments
An estimated 108,000 people die each year from potentially preventable iatrogenic injury. One in 50 hospitalized patients experiences a preventable adverse event. Up to 3% of these injuries and events take place in emergency departments. With long and detailed training, morbidity and mortality conferences, and an emphasis on practitioner responsibility, medicine has traditionally faced the challenges of medical error and patient safety through an approach focused almost exclusively on individual practitioners. Yet no matter how well trained and how careful health care providers are, individuals will make mistakes because they are human. In general medicine, the study of adverse drug events has led the way to new methods of error detection and error prevention. A combination of chart reviews, incident logs, observation, and peer solicitation has provided a quantitative tool to demonstrate the effectiveness of interventions such as computer order entry and pharmacist order review. In emergency medicine (EM), error detection has focused on subjects of high liability: missed myocardial infarctions, missed appendicitis, and misreading of radiographs. Some system-level efforts in error prevention have focused on teamwork, on strengthening communication between pharmacists and emergency physicians, on automating drug dosing and distribution, and on rationalizing shifts. This article reviews the definitions, detection, and presentation of error in medicine and EM. Based on review of the current literature, recommendations are offered to enhance the likelihood of reduction of error in EM practice.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74930/1/j.1553-2712.2000.tb00466.x.pd
Mutation analysis of Chinese sporadic congenital sideroblastic anemia by targeted capture sequencing
Cluster Headache: Interictal Asymmetric Increment in Intraocular Pressure Elicited by Valsalva Manoeuvre
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Nucleation of dislocations and their dynamics in layered oxide cathode materials during battery charging
Defects and their interactions in crystalline solids often underpin material
properties and functionality as they are decisive for stability, result in
enhanced diffusion, and act as a reservoir of vacancies. Recently, lithium-rich
layered oxides have emerged among the leading candidates for the
next-generation energy storage cathode material, delivering 50 % excess
capacity over commercially used compounds. Oxygen-redox reactions are believed
to be responsible for the excess capacity, however, voltage fading has
prevented commercialization of these new materials. Despite extensive research
the understanding of the mechanisms underpinning oxygen-redox reactions and
voltage fade remain incomplete. Here, using operando three-dimensional Bragg
coherent diffractive imaging, we directly observe nucleation of a mobile
dislocation network in nanoparticles of lithium-rich layered oxide material.
Surprisingly, we find that dislocations form more readily in the lithium-rich
layered oxide material as compared with a conventional layered oxide material,
suggesting a link between the defects and the anomalously high capacity in
lithium-rich layered oxides. The formation of a network of partial dislocations
dramatically alters the local lithium environment and contributes to the
voltage fade. Based on our findings we design and demonstrate a method to
recover the original high voltage functionality. Our findings reveal that the
voltage fade in lithium-rich layered oxides is reversible and call for new
paradigms for improved design of oxygen-redox active materials