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Influence of the freezing protocol on the activity of lactate dehydrogenase after freeze-drying
No full textFreeze-drying of pharmaceuticals, especially large molecules, has become increasingly important in recent years. Even though freeze-drying is generally considered a gentle drying process, freezing and drying conditions can affect the stability and activity of many APIs, especially proteins. The present work investigates the impact of the freezing protocol and, hence, of the structure of freeze-dried products on the activity of a model protein, i.e., lactate dehydrogenase. Using a systematic approach, the main cause of stress during the freezing and drying steps were analysed for three different freezing methods, precooled-shelf, shelf-ramped, and vacuum-induced surface freezing. As each freezing protocol led to the formation of ice crystals of different dimensions, it was found to influence the loss of activity during both freezing and drying
Prediction of ice crystal size distribution during freezing of a pharmaceutical solution
No full textIn this work, a mathematical model is presented for the prediction of the crystal size distribution of ice over the entire height of products frozen in vials. Unlike previous approaches, which were all based on empirical observations, the present one makes use of principles of chemistry and physics. In particular, we focus on a simplified version of such model and show its applicability to typical pharmaceutical formulations. The model predictions have been validated analyzing with Scanning Electron Microscopy the pore dimension of freeze-dried products, which corresponds to the ice crystal dimension of frozen products
New Families of Single-Ion Block Copolymer Electrolytes based on Poly(Ethylene Oxide) and Methacrylic Sulfonamide for Lithium Batteries
No full textPolymer electrolytes have been proposed as a replacement for conventional liquid electrolytes in next-generation lithium-based batteries, mainly because of their intrinsic enhanced safety and peculiar chemical structure that can be tailored as desired to display unique properties such as lithium-ion transference number (t+) approaching unity. This new class of materials, namely Single-Ion Conductors, has attracted increasing interest in recent years. Nevertheless, practical application of polymer electrolytes is still limited mainly by low ionic conductivity (σ), which is far below 10-5 S cm-1 at 25 °C.Herein, the preparation and characterization of new families of single-ion conducting copolymers based on the specifically designed lithium 1-[3-(methacryloyloxy)propylsulfonyl]-1-(trifluoromethylsulfonyl)imide (LiMTFSI) anionic monomer is described. RAFT polymerization was employed to prepare well-defined anionic di- and tri-block copolymers comprising poly(LiMTFSI) and poly(ethylene oxide) blocks.1 The effect of the macromolecular architecture and molecular weight on thermal and ionic conduction properties is thoroughly discussed. Block copolymers were semi crystalline, with a single glass transition temperature (Tg) due to the miscibility of the amorphous regions of both the blocks. Tg, ranging from -55 to 7 ºC, as well as degree of crystallinity (Xc, ranging from 51 to 0%) were both composition dependent. Block copolymers showed very high σ as compared to previous examples (up to ≈ 10-4 S cm-1 at 70 ºC) combined with and impressive t+ ≈ 0.91, and wide 4.5 V electrochemical stability. In addition to these promising features, solid polymer electrolytes were successfully tested in LiFePO4/Li cell prototypes at different temperatures providing long lifetime up to 300 cycles, and outstanding rate performance up to C/2 (≈100 mAh g-1)
Addressing the Controversial Mechanism of Na+ Reversible Storage in TiO2 Nanotube Arrays: Amorphous versus Anatase TiO2
No full textAmong a wide range of applications (e.g., dye-sensitized solar cells, lithium-ion batteries, supercapacitors, etc.), in its amorphous as well as most common polyphases including anatase, rutile, brookite and various metastable phases, TiO2 is under intense investigation as anode candidate for advanced electrochemical energy storage based on the sodium-ion (Na-ion) technology. Na-ion batteries (NiB) are attracting the widespread interest of the scientific community because they may offer the most convenient alternative to current leading-edge Li-ion technology (LiB) for large-scale grid energy storage, where size does not matter and cost, safety and reliability are the stringent requirements [1,2]. In the recent years, various hypotheses have been proposed on the real mechanism of reversible insertion of sodium ions into the TiO2 structure and literature reports are often controversial in this respect. Interestingly, when tested as binder- and conducting additive-free electrodes in lab-scale sodium cells, we experience intrinsically different and peculiar electrochemical response between amorphous and anatase TiO2 nanotubular arrays obtained by simple anodic oxidation. In particular, after the initial electrochemical activation, anatase TiO2 shows excellent high rate capability and very stable long-term cycling performance at larger specific capacities, thus definitely better response as compared to the amorphous counterpart. To reach deepen insights into the subject, materials are thoroughly characterized by means of scanning electron microscopy and ex-situ X-ray diffraction, and the mechanism of sodium ion insertion in the TiO2 bulk phases is systematically modelled by density functional theory (DFT) calculations, which may significantly contribute to get a more systematic selection of proper active material configurations for highly efficient sodium-based energy storage systems
An Electrolyte Study on Na2BDA Anode for Na-Based Organic Batteries
No full textEnergy production and storage plays a key role in the development of portable devices, hybrid and electric vehicles and in the energy storage system for renewable energy, such as wind and solar resources. Lithium ion batteries (LIBs) dominate the global market on these, but the geographically constrained resources and the difficult extraction of metallic lithium lead to prices increment, removing the idea of low-cost technologies. An alternative on lithium technology is sodium, very abundant, cheap and with suitable electrochemical properties, close to those of lithium. A lot of work on sodium technology has to be done in order to catch up with lithium. Electrode materials research is the first step which must be done for meet the high energy storage demand. At the moment the most common chemistries used in batteries are based on inorganic compounds (e. g. LiCoO2, LiMn2O4, Li4Ti5O12, etc…), that are expensive and synthesized from high temperature reactions, and also the end-of-life treatment is difficult and energy greedy. One possible approach as alternative is switching to the organic based materials, in which a lot of synthesis routes can be chosen and a lots of compounds can be synthesized. Furthermore, the possibility to prepare materials from recyclable organic materials (e. g. biomass) is really appealing. However, organic compounds are often associated with drawbacks such as poor conductivity, low energy density and high solubility in liquid electrolytes. Especially for the last point an accurate study on the electrolytes involved in the batteries is mandatory, because is well known how the ion-transport media affect the performances of the batteries system. In this work we present an overview on our recent results on using disodium benzenediacrylate (Na2BDA) as electrode material for Na-based organic batteries, in different electrolyte media. In particular, the galvanostatic cycling behaviors in NaǀelectrolyteǀNa2BDA pouch-cell configuration are shown
Biosourced and Lignocellulosic Materials for Electrochemical Energy Storage and Conversion
No full textIn the last 20 years, the Li-ion battery market has rapidly grown thanks to the extensive diffusion of mobile electronics devices; at the same time, dye-sensitized solar cells emerged as promising low-cost alternatives to silicon devices. In order to lower the cost and reduce the environmental impact of these energy storage and conversion devices, efforts must be devoted to reduce the amount of inactive components in the cell, to substitute synthetic polymer binders/separators and organic solvents with low-cost and biosourced materials and to develop new eco-friendly processes for the manufacture of cell components (both electrodes and electrolyte). Here we review the use of biosourced materials for manufacturing: - Bio-inspired all-paper Li-ion polymer cells, constituted by NMFC-binded paper-electrodes, and NMFC reinforced polymer electrolytes. The use of NMFC as filler/binder leads to produce high performing, safe and extremely flexible electrolytes for LiBs. No organic solvents or synthetic polymer binders are used during the entire electrode/electrolyte/cell preparation process. - Paper-based flexible electrodes and electrolytes for third generation solar cells, useful to lower oil-derived components and typical temperatures used to electrodes processing. This materials platform is promising not only for the sustainable manufacture of energy devices components, but also for their processability at the end of life. For example, the all-paper lithium cell can be easily re-dispersed in water by simple mechanical stirring, as well as common paper handsheets and battery materials can be recovered using well-known water-based recycling process
Università futura - tra democrazia e bit
No full textAbbiamo di fronte cinque sfide da cui dipende il futuro dell'umanità: ambientale, tecnologica, economica, geopolitica e democratica. Sfide a cui si aggiunge, per noi italiani, quella rappresentata dal futuro sempre più incerto del nostro paese. Su quali principi dovrebbe basarsi l'università per aiutare la società ad affrontare questi problemi? Più in generale, cosa potrebbe fare per le persone e la conoscenza? Quali metodi, quali aspetti è bene che restino invariati, e quali potrebbero invece beneficiare della rivoluzione digitale? Dopo oltre vent'anni focalizzati sugli aspetti economici della missione dell'università, è ora di riscoprirne le radici umaniste e di portarle nel ventunesimo secolo. Juan Carlos De Martin propone un'idea di università pensata per tutti coloro che hanno a cuore il futuro del nostro paese, in particolare per i ragazzi e le ragazze nati all'inizio del millennio
Un prodigio "sfortunato"? Valori e ambizioni disattese di un luogo "miracolato": il Santuario di Vicoforte (Mondovì)
No full textThis paper proposes some considerations about the plurality of values and meanings that influence the success or the failures of a place, made sacred by a religious event and by an ambitious architectural building programme. In Vico, near Mondovì, a miracle occurred in 1592 at a pillar voted to Mary. The social impact of this miracle radically changed the fate of the place, until then simply considered an anonymous and ordinary rural site. A widespread cult of devotion was triggered by the miracle, a religious process shared by both the popular and ruling classes. The royal court became involved in the devotional phenomena and the Duke Carlo Emanuele I decided that the building which was in construction around the pillar was to become the mausoleum of the House of Savoy, enriching and enhancing by this choice the sacral and political geographical configuration of the Duchy. However, the site of the miracle was not technically able to support the mass and the vastness of the sanctuary building due to a layer of clay in the soil that compromised the structure from the first years of the construction. For this reason, the church remained incomplete until the middle of the 17th century, and its whole history was blighted by structural deficiencies. Nowadays, efforts to protect the structure of the dome of the church (the world's largest oval dome) still require several innovative approaches in structural engineering. The cultural relevance of the sanctuary seems to dwell in the plurality of values and cultural interest, which concern it. This plurality is the reason for the complex cultural heritagization process that has characterized the sanctuary for more than four centuries