Underestimation of the Tambora effects in North American taiga ecosystems

The Tambora eruption (1815 AD) was one of the major eruptions of the last two millennia and has no equivalents over the last two centuries. Here, we collected an extensive network of early meteorological time series, climate simulation data and numerous, well-replicated proxy records from Eastern Canada to analyze the strength and the persistence of the Tambora impact on the regional climate and forest processes. Our results show that the Tambora impacts on the terrestrial biosphere were stronger than previously thought, and not only affected tree growth and carbon uptake for a longer period than registered in the regional climate, but also determined forest demography and structure. Increased tree mortality, four times higher than the background level, indicates that the Tambora climatic impact propagated to influence the structure of the North American taiga for several decades. We also show that the Tambora signal is more persistent in observed data (temperature, river ice dynamics, forest growth, tree mortality) than in simulated ones (climate and forest-growth simulations), indicating that our understanding of the mechanisms amplifying volcanic perturbations on climates and ecosystems is still limited, notably in the North American taiga.Peer reviewe

Towards nanoprinting with metals on graphene

Graphene and carbon nanotubes are envisaged as suitable materials for the fabrication of the new generation of nanoelectronics. The controlled patterning of such nanostructures with metal nanoparticles is conditioned by the transfer between a recipient and the surface to pattern. Electromigration under the impact of an applied voltage stands at the base of printing discrete digits at the nanoscale. Here we report the use of carbon nanotubes as nanoreservoirs for iron nanoparticles transfer on few-layer graphene. An initial Joule-induced annealing is required to ensure the control of the mass transfer with the nanotube acting as a `pen' for the writing process. By applying a voltage, the tube filled with metal nanoparticles can deposit metal on the surface of the graphene sheet at precise locations. The reverse transfer of nanoparticles from the graphene surface to the nanotube when changing the voltage polarity opens the way for error corrections

Fluorescent and magnetic stellate mesoporous silica for bimodal imaging and magnetic hyperthermia

There is currently a crucial need of innovative multifunctional nanoparticles combining, in one formulation, imaging and therapy capacities allowing thus an accurate diagnosis and a therapy monitored by imaging. Multimodal imaging will ensure to speed up diagnosis, and to increase its sensitivity, reliability and specificity for a better management of the disease. Combined with a therapeutic action, it will also enable to treat the disease in a specific personalized manner in feedback mode. The mastered design of such bioprobes as well as the demonstration of their efficiency are still challenges to face in nanomedicine. In this work, novel fluorescent and magnetic core–shell nanocomposites have been designed to ensure, in one nanoformulation, bimodal fluorescence and MRI imaging coupled with therapy by magnetic hyperthermia. They consist in the coating of a magnetic iron oxide (IO) core (ca. 18 nm diameter to ensure magnetic hyperthermia) by an original large pore stellate mesoporous silica (STMS) shell to produce uniform and mono-core magnetic core–shell nanocomposites denoted IO@STMS NPs. To confer fluorescence properties, CdSe/ZnS quantum dots (QDs) NPs were grafted inside the large pores of the IO@STMS nanocomposites. To provide biocompatibility and opsonization-resistance, a tightly-bound human serum albumin (HSA) coating is added around the nanocomposite using an original IBAM-based strategy. Cellular toxicity and non-specific cell–nanomaterial interactions allowed to determine a concentration range for safe application of these NPs. Cellular endosomes containing spontaneously-uptaken NPs displayed strong and photostable QD fluorescence signals while magnetic relaxivity measurements confirm their suitability as contrast agent for MRI. HeLa cell-uptaken NPs exposed to a magnetic field of 100 kHz and 357 Gauss (or 28.5 kA m−1) display an outstanding 65% cell death at a very low iron concentration (1.25 μg Fe mL−1), challenging current magnetic hyperthermia nanosystems. Furthermore, at the particularly demanding conditions of clinical use with low frequency and amplitude field (100 kHz, 117 Gauss or 9.3 kA m−1), magnetic hyperthermia combined with the delivery of a chemotherapeutic drug, doxorubicin, allowed 46% cell death, which neither the drug nor the NPs alone yielded, evidencing thus the synergistic effect of this combined treatment.Facultad de Ciencias VeterinariasInstituto de Investigaciones Fisicoquímicas Teóricas y AplicadasInstituto de Física La Plat

A 3D insight on the catalytic nanostructuration of few-layer graphene

The catalytic cutting of few-layer graphene is nowadays a hot topic in materials research due to its potential applications in the catalysis field and the graphene nanoribbons fabrication. We show here a 3D analysis of the nanostructuration of few-layer graphene by iron-based nanoparticles under hydrogen flow. The nanoparticles located at the edges or attached to the steps on the FLG sheets create trenches and tunnels with orientations, lengths and morphologies defined by the crystallography and the topography of the carbon substrate. The cross-sectional analysis of the 3D volumes highlights the role of the active nanoparticle identity on the trench size and shape, with emphasis on the topographical stability of the basal planes within the resulting trenches and channels, no matter the obstacle encountered. The actual study gives a deep insight on the impact of nanoparticles morphology and support topography on the 3D character of nanostructures built up by catalytic cutting

Intracellular degradation of functionalized carbon nanotube/iron oxide hybrids is modulated by iron via Nrf2 pathway.

The in vivo fate and biodegradability of carbon nanotubes is still a matter of debate despite tremendous applications. In this paper we describe a molecular pathway by which macrophages degrade functionalized multi-walled carbon nanotubes (CNTs) designed for biomedical applications and containing, or not, iron oxide nanoparticles in their inner cavity. Electron microscopy and Raman spectroscopy show that intracellularly-induced structural damages appear more rapidly for iron-free CNTs in comparison to iron-loaded ones, suggesting a role of iron in the degradation mechanism. By comparing the molecular responses of macrophages derived from THP1 monocytes to both types of CNTs, we highlight a molecular mechanism regulated by Nrf2/Bach1 signaling pathways to induce CNT degradation via NOXjournal article2017 Jan 252017 01 25importe

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Le polyacetylene hautement oriente: synthese, caracterisation structurale, dopages p chimique et electrochimique, proprietes de transport

SIGLEINIST T 73805 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Etude du comportement en adsorption d'un mélange de composés organiques volatils sur charbon actif en présence ou non de vapeur d'eau

NANCY1-SCD Sciences & Techniques (545782101) / SudocSudocFranceF

Application des mousses alvéolaires en photocatalyse (étude de la dégradation du méthanol)

Au cours de ces dernières décades, la qualité de l eau et de l air est en train de diminuer ce qui représente une menace sérieuse pour toutes les espèces vivantes. La prise de conscience des problèmes liés à l environnement a induit une forte croissance dans le domaine des recherches scientifiques et commerciales pour développer de nouveaux procédés efficaces peu onéreux en vue d améliorer la qualité de l eau et de l air. Les processus d oxydation avancée (AOP), et en particulier la photocatalyse basée sur l utilisation du dioxyde de titane (TiO2), sont considérés comme une véritable avancée par rapport aux techniques classiques de purification. Un des premiers objectifs de ce travail est de comparer deux types de réacteurs photocatalytiques de configuration toute à fait différente dans la dégradation du méthanol en phase vapeur. Un réacteur agissant en mode lit léché et un réacteur agissant en mode lit traversé à l intérieur duquel est introduite une mousse alvéolaire comme support pour le TiO2. L objectif principal est de choisir et de caractériser (voire élaborer) une mousse alvéolaire permettant d obtenir des taux de dégradation de méthanol maximaux. Trois nouveaux supports ont été choisis : les mousses de polyuréthane, de carbone et de carbure de silicium beta. Tout d abord les trois mousses ont été caractérisées. Parmi les principaux points étudiés, nous nous sommes intéressés aux phénomènes de perte de charge et de transmission de la lumière. La deuxième étape consistait à caractériser leurs fonctions de surface, notamment les fonctions oxygénées par spectrométrie XPS. La morphologie de cette surface a été observée par microscopie optique ou électronique. La surface spécifique de ces trois mousses a été mesurée. Le principal challenge consistait à optimiser la méthode de dépôt photocatalytique (TiO2-P25) sur ces trois mousses 3D alvéolaire et à s assurer que la lumière traverse bien ce type de structure alvéolaire. Après optimisation du dépôt photocatalytique sur ces trois mousses, les réacteurs garnis de ces structures alvéolaires (mode en lit traversé ) ont été utilisés pour la dégradation photocatalytique du méthanol en phase vapeur. [...]In recent decades, the gradual reduction of water and air quality has become a serious danger for all living species, among them human beings. Awareness of this environmental problem has led to a strong growth in the field of environmental scientific research and commercials equipment in order to develop new, efficient and not too expensive processes to improve the quality of water and air. Advanced oxidation process (AOP), particularly photocatalysis based on the utilization of titanium dioxide (TiO2), is considered as an advanced air and water purification technique in comparison with the other classical techniques. The first objective of this study is to compare two different configuration photocatalytic reactors for methanol degradation; seep-flow mode reactor, and traversed-flow mode reactor filled with 3D alveolar foams as a support of photocatalyst. The principal objective is to choose and characterize the most appropriate alveolar foam to obtain a maximum rate of methanol degradation. To achieve this goal, three new alveolar foams were chosen to be studied; polyurethane foam, carbon foam and beta silicon carbide foam. First of all the three foams were characterized, particularly focusing on the measurement of the pressure drop and light transmission through the foams. In the second step their functions on the surface, especially oxygen functions, were studied by XPS spectroscopy. Additionally, their surface morphology was observed by scanning electronic microscopy and transmission electron microscopy. Finally the specific surface of every foam sample was measured by BET method. The challenge was to optimize the method of photocatalyst deposition on the three alveolar foams and to assure that this process doesn t cause any decrease in the transmission of light. After this optimization, the seep-flow mode reactor and traversed-flow mode reactor (filled with 3 dimensional alveolar foams covered with photocatalyst), were used for the degradation of Methanol vapor. The essential role of the type of the reactor and the nature of the foam, in the case of traversed-flow mode reactor, were observed with several experiments of methanol degradation.[...]STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Design of Protein‐Coated Carbon Nanotubes Loaded with Hydrophobic Drugs through Sacrificial Templating of Mesoporous Silica Shells

International audienc