Influence of ion structure on thermal runaway behaviour of aprotic and protic ionic liquids

Accelerated rate calorimetric studies have been employed to study the exothermic and thermal runaway behaviour of some aprotic and protic ionic liquids based on several families of ions including the bis(flurorsulfonyl)imide anion ([FSI]^-); it was found that the protic salts are safer than aprotic salts of the [FSI]^- anion.

Thermo-electrochemical cells for waste heat harvesting - progress and perspectives

Thermo-electrochemical cells (also called thermocells) are promising devices for harvesting waste heat for the sustainable production of energy. Research into thermocells has increased significantly in recent years, driven by advantages such as their ability to continuously convert heat into electrical energy without producing emissions or consuming materials. Until relatively recently, the commercial viability of thermocells was limited by their low power output and conversion efficiency. However, there have lately been significant advances in thermocell performance as a result of improvements to the electrode materials, electrolyte and redox chemistry and various features of the cell design. This article overviews these recent developments in thermocell research, including the development of new redox couples, the optimisation of electrolytes for improved power output and high-temperature operation, the design of high surface area electrodes for increased current density and device flexibility, and the optimisation of cell design to further enhance performance.

Ionic liquids for energy, materials, and medicine

As highlighted by the recent ChemComm web themed issue on ionic liquids, this field continues to develop beyond the concept of interesting new solvents for application in the greening of the chemical industry. Here some current research trends in the field will be discussed which show that ionic liquids research is still aimed squarely at solving major societal issues by taking advantage of new fundamental understanding of the nature of these salts in their low temperature liquid state. This article discusses current research trends in applications of ionic liquids to energy, materials, and medicines to provide some insight into the directions, motivations, challenges, and successes being achieved with ionic liquids today.

Electrochemical and physicochemical properties of small phosphonium cation ionic liquid electrolytes with high lithium salt content

A novel phosphonium ionic liquid as potential candidate for lithium battery electrolytes.

Ionic liquids and ultrasound in combination: synergies and challenges

The advantages and the limits of the ionic liquid/ultrasound combination for different applications in chemistry are critically reviewed to understand how it could become an essential tool in future years.

Curcumin loaded poly(2-hydroxyethyl methacrylate) nanoparticles from gelled ionic liquid--in vitro cytotoxicity and anti-cancer activity in SKOV-3 cells

The main focus of this study is to encapsulate hydrophobic drug curcumin in hydrophilic polymeric core such as poly(2-hydroxyethyl methacrylate) [PHEMA] nanoparticles from gelled ionic liquid (IL) to improve its efficacy. We have achieved 26.4% drug loading in a biocompatible hydrophilic polymer. Curcumin loaded PHEMA nanoparticles (C-PHEMA-NPs) were prepared by nano-precipitation method. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis showed that the prepared nanoparticles were spherical in shape and free from aggregation. The size and zeta potential of prepared C-PHEMA-NPs were about 300 nm and -33.4 mV respectively. C-PHEMA-NPs were further characterized by FT-IR spectroscopy which confirmed the existence of curcumin in the nanoparticles. X-ray diffraction and differential scanning calorimetry studies revealed that curcumin present in the PHEMA nanoparticles were found to be amorphous in nature. The anticancer activity of C-PHEMA-NPs was measured in ovarian cancer cells (SKOV-3) in vitro, and the results revealed that the C-PHEMA-NPs had better tumor cells regression activity than free curcumin. Flow cytometry showed the significant reduction in G0/G1 cells after treatment with C-PHEMA-NPs and molecular level of apoptosis were also studied using western blotting. Toxicity of PHEMA nanoparticles were studied in zebrafish embryo model and results revealed the material to be highly biocompatible. The present study demonstrates the curcumin loaded PHEMA nanoparticles have potential therapeutic values in the treatment of cancer.

Bioenergetics for the growth of Staphylococcus lentus in biocompatible choline salts

Choline-based biocompatible salts were used as "nutrients" for the growth of Staphylococcus lentus bacteria. Increase in the growth rate of bacteria was observed, compared to conventional carbon sources. In the case of the ionic liquid, choline lactate, the increase was pronounced. Bacterial growth was correlated with power-time curve in an investigation monitored online by reaction calorimetry. From the power-time curve, three phases of the growth can be distinctly seen. Heat yield coefficients estimated for the growth of S. lentus were found to match well with those reported hitherto. A comparative study of heat yields (catabolic) between glucose and choline lactate revealed significant information; the heat yield due to choline lactate (Y (Q/S)) consumption and oxygen (Y (Q/O)) were 23.4 kJ/g and 435 kJ/mol and whereas that for glucose with oxygen were 9.6 kJ/g and 427 kJ/mol, respectively, showing clearly the preferential affinity of choline lactate by the bacteria rather than glucose. This study also established that the use of ionic liquids as nutrients can be monitored using bioreaction calorimetry.

Efficient Synthesis of Ellagic Acid Salts Using Distillable Ionic Liquids

A direct, one pot synthesis of an ellagic acid salt was achieved at room temperature by dimerization of ethyl gallate using N,N-dimethylammonium N′,N′-dimethylcarbamate, a distillable ionic liquid, as solvent.

Coral larvae conservation: Physiology and reproduction

Coral species throughout the world's oceans are facing severe environmental pressures. We are interested in conserving coral larvae by means of cryopreservation, but little is known about their cellular physiology or cryobiology. These experiments examined cryoprotectant toxicity, dry weight, water and cryoprotectant permeability using cold and radiolabeled glycerol, spontaneous ice nucleation temperatures, chilling sensitivity, and settlement of coral larvae. Our two test species of coral larvae, Pocillopora damicornis (lace coral), and Fungia scutaria (mushroom coral) demonstrated a wide tolerance to cryoprotectants. Computer-aided morphometry determined that F. scutaria larvae were smaller than P. damicornis larvae. The average dry weight for P. damicornis was 24.5%, while that for F. scutaria was 17%, yielding osmotically inactive volumes (V(b)) of 0.22 and 0.15, respectively. The larvae from both species demonstrated radiolabeled glycerol uptake over time, suggesting they were permeable to the glycerol. Parameter fitting of the F. scutaria larvae data yielded a water permeability 2 microm/min/atm and a cryoprotectant permeability = 2.3 x 10(-4) cm/min while modeling indicated that glycerol reached 90% of final concentration in the larvae within 25 min. The spontaneous ice nucleation temperature for F. scutaria larvae in filtered seawater was -37.8+/-1.4 degrees C. However, when F. scutaria larvae were chilled from room temperature to -11 degrees C at various rates, they exhibited 100% mortality. When instantly cooled from room temperature to test temperatures, they showed damage below 10 degrees C. These data suggest that they are sensitive to both the rate of chilling and the absolute temperature, and indicate that vitrification may be the only means to successfully cryopreserve these organisms. Without prior cryopreservation, both species of coral settled under laboratory conditions.

Living cationic polymerisation of styrene in an ionic liquidElectronic supplementary information (ESI) available: GPC results for the two-step living polymerisation of styrene by HBOB in the IL. See http://www.rsc.org/suppdata/cc/b3/b315100j/

For the first time, living cationic polymerisation of styrene has been carried out in room temperature ionic liquids under mild reaction conditions and using mild acid catalysts (e.g. organoborate acids) to obtain polymers of narrow polydispersity.

Reversible self-polymerizing high T(g) lyoprotectants

One mode of action of protectants in the storage of biological materials is by promoting the formation of a vitrified state on cooling or drying. In the case of preservation by drying, the glassy material comprises a low water content mixture of protectant and organic material. The protectant must on drying form a glassy state of glass transition temperature (T(g)) above the desired storage temperature. However, in some applications it must also be easily transported through cell membranes and this restricts the choice to a relatively limited number of small molecules, which typically exhibit very low glass transition temperatures. In this work we describe a self-polymerizing protectant comprising an inorganic salt and a small hydroxy functional molecule such as glycerol. This forms co-ordinate polymer chains of high T(g) on drying but rapidly depolymerizes into the original components on rehydration. The polymerization process is general for polyhydroxy compounds including glucose and related compounds.

Sugars exert a major influence on the vitrification properties of ethylene glycol-based solutions and have low toxicity to embryos and oocytes

A systematic approach was taken to assess the vitrification properties of ethylene glycol-based solutions supplemented with carbohydrates. Solutions were prepared by weight (gravimetrically) using ethylene glycol as the cryoprotectant, 0.9% NaCl in water, and six different sugars: d-glucose, d(-)-fructose, d-sorbitol, sucrose, d(+)-trehalose, and raffinose. Sugars were added on a molal basis (0. 1, 0.5, and 1 m). Characteristics of the solutions were measured during warming by differential scanning calorimetry using a cooling rate of 100 degrees C/min and a warming rate of 10 degrees C/min. In the absence of carbohydrates a 59 wt% EG-saline solution formed a stable glass. When EG was replaced by an equimolal concentration of glucose, fructose, or sorbitol (monosaccharides) at 0.1, 0.5, or 1.0 m there was no change in the total solute concentration at which vitrification occurred, but the glass transition (Tg) occurred at a higher temperature than in EG-saline alone. When EG was replaced by an equimolal concentration of sucrose or trehalose (disaccharides) both the Tg and the lowest total solute concentration required for vitrification became progressively higher as the molecular weight, or the ratio of sugar to EG in the solutions, increased. At the highest tested disaccharide concentration (1 m) vitrification was achieved at a total solute concentration of 65 wt% (sucrose) and 67 wt% (trehalose). The polysaccharide raffinose significantly modified the vitrification properties of ethylene glycol solutions. When 0.5 or 0.1 m raffinose replaced EG on an equimolal basis the glass transition point was raised more than with either the monosaccharides or the disaccharides. Raffinose allowed vitrification at a total solute concentration of 67 wt% (0.5 m) and 63 wt% (0.1 m). The maturation of immature mouse oocytes, and the development of embryos in media containing 5-7 mM of any sugar was comparable to controls, indicating that they are not toxic. Exposure of freshly collected GV or MII oocytes to sugar concentrations between 0.5 and 1.0 M, for up to 10 min had no significant effect on the proportion which subsequently formed two cells. We conclude that added sugars do contribute to a solutions overall vitrification properties, and their properties should be taken into consideration when vitrification solutions are being designed or modified.

Crystallization of ice in aqueous solutions of glycerol and dimethyl sulfoxide 2: ice crystal growth kinetics

The crystallization of ice in aqueous solutions of glycerol and dimethyl sulfoxide (Me2SO) has been studied using a combined DSC-video microscope technique. The solutions investigated were 50w/w% glycerol and 45w/w% Me2SO; both of these solutions have a solute concentration of approximately 16 mol%. The rates of growth of the external surfaces of ice crystals from both of these solutions were determined over broad temperature ranges. The growth rates were found to be generally independent of time, particularly at lower temperatures. The ice crystal growth rate in the glycerol solution became negligible at a significantly higher temperature than in the Me2SO solution. Addition of anti-freeze protein from the winter flounder at concentrations of 1.7 and 9.9 mg g-1 was found to have no significant effect on the ice crystal growth rates in 50w/w% glycerol solutions.

Vitrification properties of solutions of ethylene glycol in saline containing PVP, Ficoll, or dextran

Vitrification solutions which are used for cells or embryos generally contain cryoprotectant, physiological saline, and one or more macromolecular solutes. The macromolecules modify the vitrification tendencies of these solutions, but there is little detailed information on the vitrification properties of ethylene glycol solutions containing the additives PVP, Ficoll, and dextran. This study therefore added ethylene glycol to 0.9% NaCl in water (saline) and used differential scanning calorimetry to determine the lowest concentration at which the solution would remain vitreous when a warming rate of 10 degrees C/min was used. In the absence of other additives 59 wt% ethylene glycol (EG) in saline formed a stable glass. When ethylene glycol was replaced by the polymers Ficoll and/or dextran on a weight for weight basis, the resulting solution vitrified less readily than an EG-saline solution even though the total solute concentration was kept constant. The total solute concentration required to form a stable vitreous solution increased as the Ficoll 70,000 and 400,000 MW or dextran 78,000 MW content increased (5, 10, and 20 wt%). Ficoll and dextran had little or no effect on the glass transition and melting points of the solutions. In the presence of PVP vitrification occurred at a total solute concentration of 59 wt% (PVP 360,000 MW) or 60 wt% (PVP 40,000 MW) for all three tested PVP concentrations (5, 10, and 20 wt%). Although this indicates that PVP and EG have comparable vitrification properties, the melting and the glass transition temperature of the solutions rose as the PVP content increased. When 1 m sucrose was added to saline and 0, 5, 10, or 20 wt% PVP 40,000 MW vitrification was achieved with 31, 26, 23, and 15% EG, respectively, indicating that the total solute concentration required for vitrification could be estimated with reasonable accuracy from the sum of the individual components. We conclude that the tested polymers differ in how they interact with ethylene glycol-based vitrification solutions.

An association between chromosomal abnormalities in rapidly frozen 2-cell mouse embryos and the ice-forming properties of the cryoprotective solution

This paper investigates the effect of straw handling on the viability of 2-cell mouse embryos rapidly frozen in dimethyl sulphoxide (DMSO) solutions. During the brief (3 min) equilibration step, straws were either rotated periodically to keep the embryos in suspension, or kept still to allow the embryos to settle onto the the inner surface of the straw. The effects of these straw movements were tested with cryoprotectant solutions containing 1.5, 3.0 or 4.5 M-DMSO. Rapidly cooled straws containing 4.5 M-DMSO vitrify throughout on cooling, but ice forms on warming. The survival and normality of embryos frozen in 4.5 M-DMSO was not influenced by straw handling as 91-92% formed blastocysts in vitro, 77-78% formed normal fetuses, and no chromosomal rearrangements were observed. In solutions containing less than 4.5 M-DMSO ice formation occurred throughout (1.5 M-DMSO), or in parts (3.0 M-DMSO) of the cryoprotectant during cooling. The viability of embryos frozen in 3.0 or 1.5 M-DMSO solutions was reduced both in vitro and in vivo and structural chromosome aberrations, predominantly tri- and quadri-radial rearrangements, were observed. The reduction in embryo viability, and the chromosomal damage was particularly pronounced in embryos frozen in 3.0 M-DMSO in straws which were rotated during the equilibration step (47% blastocysts, 15% fetuses, 77% chromosome rearrangements). The results indicate that rapid freezing of 2-cell mouse embryos in 4.5 M-DMSO is safe and efficient, whereas freezing at lower DMSO concentrations is associated with severe chromosome damage, and reduced viability in vitro and in vivo.