192 research outputs found
De novo mitochondrial DNA alteration in child with complex neurilogical compromission.
neuromuscular human diseases have been associated with
mitochondrial DNA (mtDNA) variations, causing defects of
oxidative phosphorylation. These dysfunctions affect
preferentially tissues with high energy demands and give arise
to several degenerative disorders such as optic neuropathy,
cerebellar ataxia, movement disorders, dementia, muscle
weakness and deafness. The extremely heterogeneous clinical
phenotype is due to the involved tissue, to specific mtDNA
mutations and their heteroplasmic level, but also to nuclear
DNA alterations, environmental and epigenetic factors. In this
study we investigated a child affected by a complex
neurological disease whose clinical features were suggestive
of a mitochondrial involvement.
Methods: mtDNA from proband, her healthy relatives
(grandmother, mother and two sisters) and 80 controls were
collected and studied by sequencing. The enzymatic activity of
specific respiratory chain complex was tested on lymphocytes
by spectrophotometric assay. Bioinformatic analysis was
performed to predict the pathogenicity of the detected variants.
Results: In all subjects we detected 11 known polymorphisms,
whereas 1 novel heteroplasmic variant in complex I
[ND5:12514G>A (E60K)] was present only in the proband and
in her grandmother and absent in controls. The bioinformatics
predicted the novel variant to be deleterious. Further,
spectrophotometric assay of complex I activity was lower both
in the proband and in her relatives than in the controls.
Conclusions: We report a novel mtDNA variant detected in a
patient affected by a complex neurological disease. The
reduction of complex I respiratory chain activity associated to
this variant suggests it could exert a pathogenic role in the
disease
Flat bands as a route to high-temperature superconductivity in graphite
Superconductivity is traditionally viewed as a low-temperature phenomenon.
Within the BCS theory this is understood to result from the fact that the
pairing of electrons takes place only close to the usually two-dimensional
Fermi surface residing at a finite chemical potential. Because of this, the
critical temperature is exponentially suppressed compared to the microscopic
energy scales. On the other hand, pairing electrons around a dispersionless
(flat) energy band leads to very strong superconductivity, with a mean-field
critical temperature linearly proportional to the microscopic coupling
constant. The prize to be paid is that flat bands can generally be generated
only on surfaces and interfaces, where high-temperature superconductivity would
show up. The flat-band character and the low dimensionality also mean that
despite the high critical temperature such a superconducting state would be
subject to strong fluctuations. Here we discuss the topological and
non-topological flat bands discussed in different systems, and show that
graphite is a good candidate for showing high-temperature flat-band interface
superconductivity.Comment: Submitted as a chapter to the book on "Basic Physics of
functionalized Graphite", 21 pages, 12 figure
A new way of valorizing biomaterials: the use of sunflower protein for 1 a-tocopherol microencapsulation
Biopolymer based microparticles were efficiently prepared from sunflower protein (SP) wall material and a-tocopherol (T) active core using a spray-drying technique. Protein enzymatic hydrolysis and/or N-acylation were carried out to make some structural modifications to the vegetable protein. Native and hydrolyzed SP were characterized by Asymmetrical Flow Field-Flow Fractionation (AsFlFFF). Results of AsFlFFF confirmed that size of proteinic macromolecules was influenced by degree of hydrolysis. The effect of protein modifications and the influence of wall/core ratio on both emulsions and microparticle properties were evaluated. Concerning emulsion properties, enzymatic hydrolysis involved a decrease in viscosity, whereas acylation did not significantly affect emulsion droplet size and viscosity. Microparticles obtained with hydrolyzed SP wall material showed lower retention efficiency (RE) than native SP microparticles (62-80% and 93% respectively). Conversely, acylation of both hydrolyzed SP and native SP allowed a higher RE to be reached (up to 100%). Increasing T concentration increased emulsion viscosity, emulsion droplet size, microparticle size, and enhanced RE. These results demonstrated the feasibility of high loaded (up to 79.2% T) microparticles
Deletion of the gabra2 gene results in hypersensitivity to the acute effects of ethanol but does not alter ethanol self administration
Human genetic studies have suggested that polymorphisms of the GABRA2 gene encoding the GABA(A) α2-subunit are associated with ethanol dependence. Variations in this gene also convey sensitivity to the subjective effects of ethanol, indicating a role in mediating ethanol-related behaviours. We therefore investigated the consequences of deleting the α2-subunit on the ataxic and rewarding properties of ethanol in mice. Ataxic and sedative effects of ethanol were explored in GABA(A) α2-subunit wildtype (WT) and knockout (KO) mice using a Rotarod apparatus, wire hang and the duration of loss of righting reflex. Following training, KO mice showed shorter latencies to fall than WT littermates under ethanol (2 g/kg i.p.) in both Rotarod and wire hang tests. After administration of ethanol (3.5 g/kg i.p.), KO mice took longer to regain the righting reflex than WT mice. To ensure the acute effects are not due to the gabra2 deletion affecting pharmacokinetics, blood ethanol concentrations were measured at 20 minute intervals after acute administration (2 g/kg i.p.), and did not differ between genotypes. To investigate ethanol's rewarding properties, WT and KO mice were trained to lever press to receive increasing concentrations of ethanol on an FR4 schedule of reinforcement. Both WT and KO mice self-administered ethanol at similar rates, with no differences in the numbers of reinforcers earned. These data indicate a protective role for α2-subunits, against the acute sedative and ataxic effects of ethanol. However, no change was observed in ethanol self administration, suggesting the rewarding effects of ethanol remain unchange
Visible and Infrared Nanocrystal-Based Light Modulator with CMOS Compatible Bias Operation
Nanocrystals are now established light sources, and as synthesis and device integration have gained maturity, new functionalities can now be considered. So far, the emitted light from a nanocrystal population remains mostly driven by the structural properties (composition, size, and shape) of the particle, and only limited postsynthesis tunability has been demonstrated. Here, we explore the design of light amplitude modulators using a nanocrystal-based light-emitting diode operated under reverse bias. We demonstrate strong photoluminescence modulations for devices operating in the visible and near-telecom wavelengths using low bias operations (<3 V) compatible with conventional electronics. For a visible device based on 2D nanoplatelets, we demonstrate that the photoluminescence quenching is driven by the field-induced change of nonradiative decay rate and that the field is less involved than the particle charging. This work demonstrates that a simple diode stack can combine several functionalities (light-emitting diode, detector, and light modulator) simply by selecting the driving bias.The project is supported by ERC starting grant blackQD (Grant No. 756225) and Ne2Dem (Grant No. 853049). We acknowledge the use of clean-room facilities from the “Centrale de Proximité Paris-Centre”. This work has been supported by the Region Ile-de-France in the framework of DIM Nano-K (grant dopQD). This work is supported by French state funds managed by the ANR within the Investissements d’Avenir program under reference ANR-11-IDEX-0004-02, and more specifically within the framework of the Cluster of Excellence MATISSE and also by the grant IPER-Nano2 (ANR-18CE30-0023-01), Copin (ANR-19-CE24-0022), Frontal (ANR-19-CE09-0017), Graskop (ANR-19-CE09-0026), and NITQuantum (ANR-20-ASTR-0008–01), Bright (ANR-21-CE24–0012–02), MixDferro (ANR-21-CE09–0029) and QuickTera (ANR-22-CE09-0018). J.I.C. acknowledges support from UJI-B2021-06 and MICINN PID2021-128659NB-I00. H.Z. thanks China Scholarship Council for Ph.D. funding
Max Weber e o problema dos valores: as justificativas para a neutralidade axiológica
O presente artigo versa sobre um dos temas mais centrais das ciências sociais em geral e da obra weberiana em particular, qual seja, o debate em torno do engajamento ou do distanciamento do cientista em relação à realidade social que constitui seu objeto. No decorrer deste texto é realizado um escrutínio da posição de Max Weber em torno dessa questão, que é condensada na sua defesa de uma postura de "neutralidade axiológica". Mais do que identificar o sentido atribuído a esta ideia, o objetivo que norteou a pesquisa foi o de apreender as justificativas apresentadas por Weber para conferir sustentação a essa premissa. A primeira etapa da pesquisa consistiu em uma uma leitura estrutural de todos os textos de Max Weber que versam sobre o tema em questão e que compõem a coletânea Gesammelte Aufsätze zur Wissenschaftslehre, conforme explicitado de modo detalhado na segunda seção do artigo. A partir disso foram selecionados todos os trechos contendo a expressão "neutralidade axiológia" e outros termos correlatos, apresentados na tabela em anexo. Esses trechos foram então classificados e analisados em relação ao seu conteúdo, com o intuito de apreender as justificativas apresentadas pelo autor. Ao final, todos esses dados foram mobilizados e sintetizado de modo a se produzir considerações mais gerais sobre a teoria do autor em questão. O principal resultado da investigação, que é aqui apresentado, é uma compreensão mais ampla e profunda das justificativas subjacentes a uma das posições mais cruciais da sociologia weberiana, e que permite um posicionamento mais bem informado em relação a essa temática que ainda se mantém como um dos pilares das reflexões epistemológicas nas ciências sociais contemporâneas. Portanto, o artigo contribui para o debate lançando uma nova luz sobre as premissas que estruturam a defesa do princípio da neutralidade axiológica, explicitando que a defesa de tal princípio se deve a uma pluralidade de justificativas. Além disso, a discussão aqui apresentada permite compreender com mais clareza as consequências dessa defesa da neutralidade axiológica para a ciência e para a vida social
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