Facile and sustainable synthesis of nitrogen-doped polymer and carbon porous spheres

International audienceThe development of green, sustainable and simple synthesis pathways for the design of polymer and carbonaceous materials with well controlled features is of great importance for many fields of applications. Herein, we report a green synthesis method for polymer and carbon particles with well-defined shape and size. This approach involves the use of green precursors, water as solvent, no templates 10 under ambient temperature and pressure conditions, simultaneously. Green polymer resins (phloroglucinol-glyoxylic acid) and a catalyst/nitrogen source (triethylenediamine) are dissolved in water at room temperature resulting in polymer particles which by subsequent thermal treatment transforms in carbon particles. Mainly spherical carbon particles with controlled size from 500 nm to 10 µm were obtained by simply adjusting the experimental conditions, i.e., the synthesis time and the molar ratio between the precursors or solvent. In some conditions, flower-like morphology was obtained as well. The synthesis mechanism from polymer resin spheres 15 formation to their conversion into carbon sphere was determined by several techniques, i.e., 13 C NMR spectroscopy, SEM, XPS and TPD-MS (temperature programmed desorption coupled by mass spectrometer). 2

Development of and Access to Products for Neglected Diseases

INTRODUCTION: Prior research on neglected disease drug development suggested inadequate funding was responsible for relatively few new approvals. In response, significantly more resources have been allocated towards development of drugs targeting neglected diseases. Our objective was to reassess drug development between 1975 and 1999, evaluate progress in neglected disease drug development since 2000, and explain how increased numbers of approvals are a necessary but insufficient condition to improving access. METHODS: To assess numbers of approvals targeting neglected diseases, we employed two distinct methodologies: First, to revisit numbers published in Trouiller et al. (2002) we used their method to count marketed new chemical entities (NCEs) between 1975 and 1999. Second, using the G-Finder report as a benchmark, we identified which diseases are currently considered "neglected" to tally approvals in the 1975-1999 and 2000-2009 periods. Searching PharmaProjects and IMS R&D Focus databases as well as websites from numerous drug regulatory agencies, we identified new drug approvals and indications. Also, we examined the World Health Organization's (WHO) Essential Drug List (EDL) to see which drugs and indications were on the list. FINDINGS: Upon recount, using Trouiller et al. methodology, we found that between 1975 and 1999 more NCEs (n = 32) targeting tropical diseases and tuberculosis were approved than reported in Trouiller et al. (n = 16). Using the G-Finder method of defining neglected diseases, we found 46 new drug approvals between 1975 and 1999. WHO included 85% of these drugs on the EDL. In the period 2000 to May 2009, despite much greater funding, only 26 new drugs and vaccines for neglected diseases were marketed. Of these, WHO placed 50% on the EDL. CONCLUSIONS: Product approvals for neglected diseases have increased, though progress has been uneven, with malaria appearing to benefit most in the short run from increased funding, while less success has been booked in other disease categories. Uneven progress suggests funding could be better targeted, particularly with regard to neglected diseases that have hitherto received scant attention. In addition, policymakers should focus on other aspects related to access. Besides drug development, there are the issues of EDL listing, architecture, availability, affordability, and adoption

Hard carbon derived from coconut shells, walnut shells, and corn silk biomass waste exhibiting high capacity for Na-ion batteries

International audienceIn recent years, hard carbon materials have gained significant interest as anode materials for Na-ion batteries. Biomass waste is considered one of the most interesting, renewable, available, and cost-effective precursor to obtain hard carbon (HC); however, HC properties must be finely tuned to achieve performance comparable to those provided by Li-ion batteries. In this work, three biomass wastes (coconut shells, walnut shells, and corn silk) were evaluated as potential precursors for HC preparation involving a pyrolysis process and subsequent acid washing to remove the inorganic impurities. All obtained materials exhibited low and similar specific surface areas (< 10 m 2 g-1), but they presented different structures and surface functionalities. The walnut shell HC possessed a lower amount of inorganic impurities and oxygen-based functional groups compared to the coconut shell and corn silk HCs, leading to higher initial coulombic efficiency (iCE). The structural organization was higher in the case of the walnut shell HC, while the corn silk HC revealed a heterogeneous structure, combining both highly disordered carbon and localized graphitized domains. All HCs delivered high initial reversible capacities between 293 and 315 mAh g-1 at 50 mA g-1 current rate, which remained rather stable during long-term cycling. The best capacity (293 mAh g-1 after 100 charge/discharge cycles) and highest capacity retention (93%) was achieved in walnut HCs in half-cells, which could be associated with its higher sp 2 C content, better organized structure, and fewer impurities. An "adsorption-insertion" Na storage mechanism is suggested based on several techniques. The walnut HCs exhibited an attractive energy density of 279 Wh/kg when tested in full cells

Nanoconfinement of glucose oxidase on mesoporous carbon electrodes with tunable pore sizes

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Nanoconfinement of glucose oxidase on mesoporous carbon electrodes with tunable pore sizes

By using a series of nanoporous carbons with a controlled distribution of pore sizes we have demonstrated the effect of commensurate confinement in the nanopores of the carbon electrodes in the electrochemical and enzymatic activity of immobilized glucose oxidase. The nanoconfinement resulted in more efficient oxidation of glucose through direct electron tunneling of the flavin adenine dinucleotide (FAD) site and the electrode surface. The electrochemical and enzymatic activity was boosted in carbon materials with pores which size matched the dimensions of the enzyme. This is attributed to the conformational changes of the biomolecule in the nanoconfined state, and the proximity of the FAD active site and the carbon electrode pores/walls boosts the electron transfer even in the absence of a mediator. The thermal profiles of the immobilized enzyme provided direct evidence of the conformational changes in the nanoconfined state, and their correlation with the average mesopore size of the carbon material. For the material showing the most adequate porosity, the nanoconfined enzyme retained the electrocatalytic activity towards glucose oxidation -even in the absence of mediator-, and at a broad range of concentrations. This approach is essential to make further clear some critical issues about the immobilization of enzymes on nanoporous carbon electrodes for bioelectrochemical applications.COA thanks the financial support of the European Research Council through a Consolidator Grant (ERC-CoG-648161, PHOROSOL), the Spanish MINECO through an excellence network E3TECH (grant CTQ2015-71650-RDT), and CNRS for a mobility action (poste rouge).Peer reviewe

Inorganic-Organic Thin Implant Coatings Deposited by Lasers

International audienceThe lifetime of bone implants inside the human body is directly related to their osseointegration. Ideally, future materials should be inspired by human tissues and provide the material structurefunction relationship from which synthetic advanced biomimetic materials capable of replacing, repairing, or regenerating human tissues can be produced. This work describes the development of biomimetic thin coatings on titanium implants to improve implant osseointegration. The assembly of an inorganicorganic biomimetic structure by UV laser pulses is reported. The structure consists of a hydroxyapatite (HA) film grown onto a titanium substrate by pulsed-laser deposition (PLD) and activated by a top fibronectin (FN) coating deposited by matrix-assisted pulsed laser evaporation (MAPLE). A pulsed KrF* laser source (lambda = 248 nm, tau = 25 ns) was employed at fluences of 7 and 0.7J/cm(2) for HA and FN transfer, respectively. Films approximately 1500 and 450 nm thick were obtained for HA and FN, respectively. A new cryogenic temperature-programmed desorption mass spectrometry analysis method was employed to accurately measure the quantity of immobilized protein. We determined that less than 7 mu g FN per cm(2) HA surface is adequate to improve adhesion, spreading, and differentiation of osteoprogenitor cells. We believe that the proposed fabrication method opens the door to combining and immobilizing two or more inorganic and organic materials on a solid substrate in a well-defined manner. The flexibility of this method enables the synthesis of new hybrid materials by simply tailoring the irradiation conditions according to the thermo-physical properties of the starting materials

Characterization of Carbon Surface Chemistry by Combined Temperature Programmed Desorption with in Situ X-ray Photoelectron Spectrometry and Temperature Programmed Desorption with Mass Spectrometry Analysis

The analysis of the surface chemistry of carbon materials is of prime importance in numerous applications, but it is still a challenge to identify and quantify the surface functional groups which are present on a given carbon. Temperature programmed desorption with mass spectrometry analysis (TPD-MS) and X-ray photoelectron spectroscopy with an in situ heating device (TPD-XPS) were combined in order to improve the characterization of carbon surface chemistry. TPD-MS analysis allowed the quantitative analysis of the released gases as a function of temperature, while the use of a TPD device inside the XPS setup enabled the determination of the functional groups that remain on the surface at the same temperatures. TPD-MS results were then used to add constraints on the deconvolution of the O1s envelope of the XPS spectra. Furthermore, a better knowledge of the evolution of oxygen functional groups with temperature during a thermal treatment could be obtained. Hence, we show here that the combination of these two methods allows to increase the reliability of the analysis of the surface chemistry of carbon materials