Analysis of competitive binding of several metal cations by graphene oxide reveals the quantity and spatial distribution of carboxyl groups on its surface

2018 ◽  
Vol 20 (4) ◽  
pp. 2320-2329 ◽  
Author(s):  
Rustem R. Amirov ◽  
Julia Shayimova ◽  
Zarina Nasirova ◽  
Alexander Solodov ◽  
Ayrat M. Dimiev
Keyword(s):  
Spatial Distribution ◽  
Graphene Oxide ◽  
Binding Sites ◽  
Metal Cations ◽  
Competitive Binding ◽  
Carboxyl Groups ◽  
Different Types

GO contains two different types of binding sites, bonding to which results either in high or low NMR relaxivity of resulted Gd3+–GO and Mn2+–GO solutions.

Carboxyl Groups do not Play the Major Role in Binding Metal Cations by Graphene Oxide

2021 ◽  
Author(s):  
Julia Shayimova ◽  
Rustem R. Amirov ◽  
Artem Iakunkov ◽  
Alexandr Talyzin ◽  
Ayrat Dimiev
Keyword(s):  
Graphene Oxide ◽  
Aqueous Solutions ◽  
Nmr Relaxation ◽  
Metal Cations ◽  
Carboxyl Groups ◽  
Chemical Interactions ◽  
Graphene Oxides

In this study, we investigate chemical interactions of Mn2+ ions with graphene oxides, prepared by Hummers (HGO) and Brodie (BGO) methods in aqueous solutions by means of the NMR relaxation....

Movement of Calcium Ions and their Role in the Activation of Platelets

1978 ◽  
Vol 40 (02) ◽  
pp. 212-218 ◽  
Author(s):  
P Massini ◽  
R Käser-Glanzmann ◽  
E F Lüscher
Keyword(s):  
Plasma Membrane ◽  
Platelet Activation ◽  
Calcium Ions ◽  
Binding Sites ◽  
Shape Change ◽  
Release Reaction ◽  
Dense Bodies ◽  
Activated Platelets ◽  
Different Types ◽  
Ca Ions

SummaryThe increase of the cytoplasmic Ca-concentration plays a central role in the initiation of platelet activation. Four kinds of movements of Ca-ions are presumed to occur during this process: a) Ca-ions liberated from membranes induce the rapid shape change, b) Vesicular organelles release Ca-ions into the cytoplasm which initiate the release reaction, c) The storage organelles called dense bodies, secrete their contents including Ca-ions to the outside during the release reaction, d) At the same time a rearrangement of the plasma membrane occurs, resulting in an increase in its permeability for Ca-ions as well as in an increase in the number of Ca-binding sites.Since most processes occurring during platelet activation are reversible, the platelet must be equipped with a mechanism which removes Ca-ions from the cytoplasm. A vesicular fraction obtained from homogenized platelets indeed accumulates Ca actively. This Ca- pump is stimulated by cyclic AMP and protein kinase; it may be involved in the recovery of platelets after activation.It becomes increasingly clear that the various manifestations of platelet activation are triggered by a rise in the cytoplasmic Ca2+-concentration. The evidence for this and possible mechanisms involved are discussed in some detail in the contributions by Detwiler et al. and by Gerrard and White to this symposium. In this article we shall discuss four different types of mobilization of Ca-ions which occur in the course of the activation of platelets. In addition, at least one transport step involved in the removal of Ca2+ must occur during relaxation of activated platelets.

Distribution of fungi in a Triassic fern stem

2017 ◽  
Vol 108 (4) ◽  
pp. 387-398 ◽  
Author(s):  
Carla J. Harper ◽  
Jean Galtier ◽  
Thomas N. Taylor ◽  
Edith L. Taylor ◽  
Ronny Rößler ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Host Response ◽  
Host Tissue ◽  
Tissue Preservation ◽  
Fossil Plants ◽  
Fossil Plant ◽  
Distribution Maps ◽  
Different Types ◽  
Fungal Distribution ◽  
Fungal Associations

ABSTRACTDocumented evidence of fungi associated with Mesozoic ferns is exceedingly rare. Three different types of fungal remains occur in a portion of a small, permineralised fern stem of uncertain systematic affinities from the Triassic of Germany. Exquisite preservation of all internal tissues made it possible to map the spatial distribution of the fungi in several longitudinal and transverse sections. Narrow, intracellular hyphae extend through the entire cortex, while wide hyphae are concentrated in the cortical intercellular system adjacent to the stele and leaf traces. Hyphal swellings occur in the phloem and adjacent cortex, while moniliform hyphae (or chains of conidia) are present exclusively in parenchyma adjacent to the stele. No host response is recognisable, but host tissue preservation suggests that the fern was alive during fungal colonisation. The highest concentration of fungal remains occurs close to the stele and leaf traces, suggesting that the fungi either utilised the vascular tissues as an infection/colonisation pathway or extracted nutrients from these tissues. This study presents the first depiction of fungal distribution throughout a larger portion of a fossil plant. Although distribution maps are useful tools in assessing fungal associations in relatively small, fossil plants, preparing similar maps for larger and more complex fossils would certainly be difficult and extremely arduous.

scholarly journals Large-scale integrated subglacial drainage around the former Keewatin Ice Divide, Canada reveals interaction between distributed and channelised systems

2020 ◽  
Author(s):  
Emma L. M. Lewington ◽  
Stephen J. Livingstone ◽  
Chris D. Clark ◽  
Andrew J. Sole ◽  
Robert D. Storrar
Keyword(s):  
Spatial Distribution ◽  
Dynamic Response ◽  
Large Scale ◽  
Water Pressure ◽  
Pressure Fluctuations ◽  
Drainage System ◽  
Different Types ◽  
Form Part ◽  
Subglacial Meltwater ◽  
Subglacial Drainage

Abstract. We identify and map traces of subglacial meltwater drainage around the former Keewatin Ice Divide, Canada from ArcticDEM data. Meltwater tracks, tunnel valleys and esker splays exhibit several key similarities, including width, spacing, their association with eskers and transitions to and from different types, which together suggest they form part of an integrated drainage signature. We collectively term these features 'meltwater corridors' and propose a new model for their formation, based on observations from contemporary ice masses, of pressure fluctuations surrounding a central conduit. We suggest that eskers record the imprint of a central conduit and meltwater corridors the interaction with the surrounding distributed drainage system. The widespread aerial coverage of meltwater corridors (5–36 % of the bed) provides constraints on the extent of basal uncoupling induced by basal water pressure fluctuations and variations in spatial distribution and evolution of the subglacial drainage system, which will modulate the ice dynamic response.

scholarly journals Graphene Oxide Nano-Concentrators Selectively Modulate RNA Trapping According to Metal Cations in Solution

2020 ◽  
Vol 8 ◽  
Author(s):  
Valentina Palmieri ◽  
Lorena Di Pietro ◽  
Giordano Perini ◽  
Marta Barba ◽  
Ornella Parolini ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Metal Cations

scholarly journals Is carboxylation an efficient method for graphene oxide functionalization?

2020 ◽  
Vol 2 (9) ◽  
pp. 4085-4092
Author(s):  
Shi Guo ◽  
Jésus Raya ◽  
Dingkun Ji ◽  
Yuta Nishina ◽  
Cécilia Ménard-Moyon ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Efficient Method ◽  
Chloroacetic Acid ◽  
Carboxyl Groups ◽  
Partial Reduction

We investigated the carboxylation of graphene oxide using chloroacetic acid and different amounts of NaOH. Increase of carboxyl groups was observed only at high amounts of NaOH, but partial reduction attenuates the yield of further functionalization.

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