165 research outputs found
Sulfur isotope evolution in sulfide ores from Western Alps: Assessing the influence of subduction-related metamorphism
Sulfides entering subduction zones can play an important role in the release of sulfur and metals to the mantle wedge and contribute to the formation of volcanic arc-associated ores. Fractionation of stable sulfur isotopes recorded by sulfides during metamorphism can provide evidence of fluid-rock interactions during metamorphism and give insights on sulfur mobilization. A detailed microtextural and geochemical study was performed on mineralized samples from two ocean floor-related sulfide deposits (Servette and Beth-Ghinivert) in high-pressure units of the Italian Western Alps, which underwent different metamorphic evolutions. The combination of microtextural investigations with d34S values from in situ ion probe analyses within individual pyrite and chalcopyrite grains allowed evaluation of the effectiveness of metamorphism in modifying the isotopic record and mobilizing sulfur and metals and have insights on fluid circulation within the slab. Textures and isotopic compositions inherited from the protolith are recorded at Beth-Ghinivert, where limited metamorphic recrystallization is attributed to limited interaction with metamorphic fluids. Isotopic modification by metamorphic processes occurred only at the submillimeter scale at Servette, where local interactions with infiltrating hydrothermal fluid are recorded by metamorphic grains. Notwithstanding the differences recorded by the two deposits, neither underwent intensive isotopic reequilibration or records evidence of intense fluid-rock interaction and S mobilization during metamorphism. Therefore, subducted sulfide deposits dominated by pyrite and chalcopyrite are unlikely to release significant quantities of sulfur to the mantle wedge and to arc magmatism sources at metamorphic grades below the lower eclogite facies
Chemical proteomics approaches for identifying the cellular targets of natural products.
Covering: 2010 up to 2016. Deconvoluting the mode of action of natural products and drugs remains one of the biggest challenges in chemistry and biology today. Chemical proteomics is a growing area of chemical biology that seeks to design small molecule probes to understand protein function. In the context of natural products, chemical proteomics can be used to identify the protein binding partners or targets of small molecules in live cells. Here, we highlight recent examples of chemical probes based on natural products and their application for target identification. The review focuses on probes that can be covalently linked to their target proteins (either via intrinsic chemical reactivity or via the introduction of photocrosslinkers), and can be applied "in situ" - in living systems rather than cell lysates. We also focus here on strategies that employ a click reaction, the copper-catalysed azide-alkyne cycloaddition reaction (CuAAC), to allow minimal functionalisation of natural product scaffolds with an alkyne or azide tag. We also discuss 'competitive mode' approaches that screen for natural products that compete with a well-characterised chemical probe for binding to a particular set of protein targets. Fuelled by advances in mass spectrometry instrumentation and bioinformatics, many modern strategies are now embracing quantitative proteomics to help define the true interacting partners of probes, and we highlight the opportunities this rapidly evolving technology provides in chemical proteomics. Finally, some of the limitations and challenges of chemical proteomics approaches are discussed
Bio-orthogonal Fluorescent Labelling of Biopolymers through Inverse-Electron-Demand DielsâAlder Reactions
Bio-ort
hogona
llabellin
gschemes
based
on inverse-elec
tron-
deman
dDielsâAld
er (IEDDA)
cycloa
ddition
have
attracted
much
attention
in chem
ical biology
recently
.The appeal
ing
features
of this reactio
n, such
as the fast reactio
nkinetics,
fully
bio-ort
hogonal
nature
and high
selectiv
ity,have helped
chem
i-
cal biologists
gain
deeper
understandi
ng of biochemic
al pro-
cesses
at the molecular
level.Listing
the compo
nents
and dis-
cussing
the possib
ilities
andlimitations
of thesereagent
s, we
provid
earecent
snapshot
of the field
of IEDDA
-based
biomo-
lecular
manipulatio
nwith special
focus
on fluores
cent
modula-
tion
approaches
throug
hthe use of bio-orthogon
alized
build-
ing blocks.
At the end,
we discuss
challenges
that
need
to be
addres
sed
for further
develop
ments
in order
to overcome
recent
limita
tions
and to enabl
eresearchers
to answer
biomo
-
lecular
quest
ions in more
detail
Publier le métier, quelles perspectives ?
L\u27enjeu de cette journée est de réfléchir aux mutations actuelles de la production et de la diffusion de ressources à destination des communautés professionnelles des bibliothÚques :
- Ădition de manuels et ressources en ligne
- Recherches et réflexions professionnelles, ouvertes à de nouveaux métiers
- Ăditions homothĂ©tiques ou "pure player"
- Modes de production spécifiques : ressources continues, blogs, carnets de recherche, tutoriels et manuels en ligne, etc.
Crise du modĂšle actuel ? Ăvolution des besoins, des pratiques de lecture, des pratiques dâĂ©criture ? ⊠Sans doute un peu tout Ă la fois.
Alors, comment penser l\u27avenir d\u27une littérature professionnelle utile
'Vernacular Voices: Black British Poetry'
ABSTRACT
Black British poetry is the province of experimenting with voice and recording rhythms beyond the iambic pentameter. Not only in performance poetry and through the spoken word, but also on the page, black British poetry constitutes and preserves a sound archive of distinct linguistic varieties. In Slave Song (1984) and Coolie Odyssey (1988), David Dabydeen employs a form of Guyanese Creole in order to linguistically render and thus commemorate the experience of slaves and indentured labourers, respectively, with the earlier collection providing annotated translations into Standard English. James Berry, Louise Bennett, and Valerie Bloom adapt Jamaican Patois to celebrate Jamaican folk culture and at times to represent and record experiences and linguistic interactions in the postcolonial metropolis. Grace Nichols and John Agard use modified forms of Guyanese Creole, with Nichols frequently constructing gendered voices whilst Agard often celebrates linguistic playfulness. The borders between linguistic varieties are by no means absolute or static, as the emergence and marked growth of âLondon Jamaicanâ (Mark Sebba) indicates. Asian British writer Daljit Nagra takes liberties with English for different reasons. Rather than having recourse to established Creole languages, and blending them with Standard English, his heteroglot poems frequently emulate âPunglishâ, the English of migrants whose first language is Punjabi. Whilst it is the language prestige of London Jamaican that has been significantly enhanced since the 1990s, a fact not only confirmed by linguistic research but also by its transethnic uses both in the streets and on the page, Nagraâs substantial success and the mainstream attention he receives also indicate the clout of vernacular voices in poetry. They have the potential to connect with oral traditions and cultural memories, to record linguistic varieties, and to endow âstreet credâ to authors and texts. In this chapter, these double-voiced poetic languages are also read as signs of resistance against residual monologic ideologies of Englishness.
© Book proposal (02/2016): The Cambridge History of Black and Asian British Writing p. 27 of 4
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Forging connections: anthologies, arts collectives, and the politics of inclusion
The changing social and political landscape of twentieth-century Britain catalysed a remarkable rise in collaborative activity by artists and activists of black and Asian heritage. Creative communities began to gather in both local and regional contexts, with the aim of sharing resources and securing an audience. This chapter records some of these many activities, tracing the groupsâ genesis, manifest objectives, and key contributions. It argues that anthologising should be understood as a specifically motivated activity. Literary anthologies of poetry and fiction served to showcase the diversity of contemporary writing, while also suggesting its coherence. Drawing on the concept of âstrategic essentialismâ elucidated by Gayatri Chakravorty Spivak, I show that the anthology acts to ensure the visibility of a group, bannered as a unified and singly-titled selection of texts, while also insisting on the differences within: the heterogeneous multiplicity of black and Asian British experiences and creative practices
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