56 research outputs found
Point contact spectroscopy of the electron-doped cuprate superconductor Pr{2-x}Ce{x}CuO4: The dependence of conductance-voltage spectra on cerium doping, barrier strength and magnetic field
We present conductance-voltage (G-V) data for point contact junctions between
a normal metal and the electron doped cuprate superconductor Pr{2-x}Ce{x}CuO4
(PCCO). We observe a zero bias conductance peak (ZBCP) for the under-doped
composition of this cuprate (x=0.13) which is consistent with d-wave pairing
symmetry. For optimally-doped (x=0.15) and over-doped (x=0.17) PCCO, we find
that the G-V characteristics indicate the presence of an order parameter
without nodes. We investigate this further by obtaining point contact
spectroscopy data for different barrier strengths and as a function of magnetic
field.Comment: 13 pages, 9 figure
Cooperativity and flexibility in enzyme evolution
Enzymes are flexible catalysts, and there has been substantial
discussion about the extent to which this flexibility contributes
to their catalytic efficiency. What has been significantly less
discussed is the extent to which this flexibility contributes to
their evolvability. Despite this, recent years have seen an
increasing number of both experimental and computational
studies that demonstrate that cooperativity and flexibility play
significant roles in enzyme innovation. This review covers key
developments in the field that emphasize the importance of
enzyme dynamics not just to the evolution of new enzyme
function(s), but also as a property that can be harnessed in the
design of new artificial enzymes.The European Research Council has provided financial support under the
European Community’s Seventh Framework Program (FP7/2007-2013)/ERC
Grant Agreement No. 306474. This work was also funded by the Feder
Funds, Grants from the Spanish Ministry of Economy and Competitiveness
(BIO2015-66426-R and CSD2009-00088) and the Human Frontier Science
Program (RGP0041/2017). A.P. is a Wenner-Gren Foundations Postdoctoral
Fellow and S. C. L. K. is a Wallenberg Academy Fellow
Gene expression during zombie ant biting behavior reflects the complexity underlying fungal parasitic behavioral manipulation
Political Jiu-Jitsu against Indonesian Repression: Studying Lower-Profile Nonviolent Resistance
Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases
The production of peroxide and superoxide is an inevitable consequence of
aerobic metabolism, and while these particular "reactive oxygen species" (ROSs)
can exhibit a number of biological effects, they are not of themselves
excessively reactive and thus they are not especially damaging at physiological
concentrations. However, their reactions with poorly liganded iron species can
lead to the catalytic production of the very reactive and dangerous hydroxyl
radical, which is exceptionally damaging, and a major cause of chronic
inflammation. We review the considerable and wide-ranging evidence for the
involvement of this combination of (su)peroxide and poorly liganded iron in a
large number of physiological and indeed pathological processes and
inflammatory disorders, especially those involving the progressive degradation
of cellular and organismal performance. These diseases share a great many
similarities and thus might be considered to have a common cause (i.e.
iron-catalysed free radical and especially hydroxyl radical generation). The
studies reviewed include those focused on a series of cardiovascular, metabolic
and neurological diseases, where iron can be found at the sites of plaques and
lesions, as well as studies showing the significance of iron to aging and
longevity. The effective chelation of iron by natural or synthetic ligands is
thus of major physiological (and potentially therapeutic) importance. As
systems properties, we need to recognise that physiological observables have
multiple molecular causes, and studying them in isolation leads to inconsistent
patterns of apparent causality when it is the simultaneous combination of
multiple factors that is responsible. This explains, for instance, the
decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference
Modified purse string closure for excisional biopsy of pigmented lesions on extremities
Proper selection of biopsy technique is imperative, especially when approaching a suspicious pigmented lesion on the extremity. When possible, a complete excisional biopsy with narrow margins is preferred to prevent partial sampling and inadequate evaluation of a lesion. A vertically oriented fusiform excisional biopsy is often selected for biopsy as it preserves lymphatics and prevents circumferential scarring. In this communication, we highlight possible pitfalls of selecting a fusiform ellipse for potential melanomas and provide a patient centered step-by-step guide to the use of narrow excisional biopsy with modified purse string closure. Purse string closure for biopsy of suspected melanoma is both tissue sparing at the time of biopsy and definitive excision. This approach also minimizes the possibility of interfering with lymphatic drainage should a sentinel lymph node biopsy be warranted. Although traditional purse string closures demonstrate similar cosmetic outcomes to secondary intention wounds, they allow for simplified wound care. The use of modifying dermal sutures allows for similar cosmetic outcomes to that of a linear excision
Modified-purse-string closure: A lymphatic channel and tissue sparing technique for biopsy of suspicious pigmented lesions on extremities
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