In the field of high-temperature thermal energy storage, the use of reacting systems that reversibly decompose and regenerate, absorbing and releasing heat on demand, is becoming more and more attractive. It is essential in the perspective of achieving high thermal energy density storage, appearing potentially suitable for long-term applications too. Thermochemical Systems (TCS) can contribute to increasing the dispatchability of thermal storage, potentially even on a seasonal timescale. So far, most of this field's scientific works have focused on the conventional concept of fixed-bed reactors.To improve the heat transport phenomena involved in TCS storage, a fluidized bed solution was considered in this article. At this aim, a manganese aluminium spinel, which is a low toxic, low pollutant and very cost-effective is proposed for this application. It was synthesized in the form of properly sized (150-200 mu m of diameter) particles to be effectively adopted for fluidizing beds. The present work deals with the sizing of the reactor and its coupling with a Concentrating Solar Thermal (CST) system using the Solar Central Receiver (SCR) technology with air as Heat Transfer Fluid (HTF). Imposing realistic boundaries, an optimal configuration was established, with an operating HTF pressure of 4 bar and a thermal discharging power of about 16 MWth. A volumetric energy density of 170 kWhth/m3 was achieved and, despite a relatively low TES reaction enthalpy, the resulting specific cost of 33 euro/kWh demonstrates the suitability of this configuration even for the current thermal storage commercial solution, and shows the high potentiality of this type of storage systems.

ThermoChemical Storage systems (TCS) are gaining attention for long term-thermal energy storage applications. Those systems can successfully increase the electricity generation flexibility in CSP (Concentrated Solar Power) plants or optimize the heat recovery and storage in energy-intensive industries (EII) as well. CaO/CaCO3 based systems are currently broadly investigated for thermochemical storage, either natural or synthetic materials. Among these, CaO/Mayenite (Ca12Al14O33) sorbents are considered very promising. CaO/Mayenite (Ca12Al14O33) based material was developed according to two different synthesis methods. The first one con-sisted in a one-step sol-gel method where aluminium precursor and pure CaO are weighted to obtain the exact weight ratio of 75/25 (CaO/Ca12Al14O33). In the second one, a two-step method was adopted: pure Mayenite was preliminarily synthetized by one step sol-gel method and CaO/Mayenite was obtained by direct wet mixing with pure CaO. Samples obtained were characterized by XRD, SEM, TGA, nitrogen physisorption, Raman spectroscopy and thermal stability was tested over 40 charging/discharging cycles in TGA. Raman spectra revealed free ox-ygen O2 � presence in the structure of Mayenite and in CaO-Mayenite samples as well, lying at 1128 cm-1. Thermal properties such as thermal conductivity, heat capacity and volumetric energy density storage have been deter-mined. The thermal conductivity found were 0.377 & PLUSMN; 0.004 (W/mK) for A; 0.101 & PLUSMN; 0.006 (W/mK) for B and for Mayenite 1.16 & PLUSMN; 2.7 10-4 (W/mK). It was found that two step method led to a better performing material in terms of carbonation reaction reactivity, and hence thermal storage. This material showed 50 % carbonation reaction conversion value at 40th cycle, corresponding to 0.250 g CO2/g dry sample, which is 4 times higher than CaO conversion. At 40th cycle, moderate sintering effect is remarked, with 2.3 % conversion drop, indicating that Mayenite insertion effectively acts as spacer. Volumetric storage energy density Sd has been determined for both samples and compared to CaO at increasing cycle number. Sample B storage density was effectively even at 40th cycle with 0.69 GJ/m3, thus about 3.5 times higher than CaO.

Parabolic trough concentrated solar power (CSP) plants are particularly promising renewable sources of energy, whose easy integration with thermal energy storage (TES) systems allows to mitigate the intermittency of electricity generation. Currently, molten nitrates, with two tanks arrangement, are mainly used for sensible heat accumulation. To reduce costs and make the CSP storage systems more manageable, single tank configurations have been proposed, where the cold and hot fluids are stored in the same container and separated because of their density difference. The aim of the present work is to study the storage performances presented by two novel ternary and quaternary mixtures, proposed within the European project IN POWER. An experimental campaign was preliminarily performed to investigate the fluids thermo-physical properties, and the obtained values were utilized as input data to model the discharge phase in a thermocline tank. The simulation results were compared with the ones acquired considering two commercial materials, namely, solar salt and Hitec XL (R). Overall, considering same temperature ranges, higher discharging times are obtained for the quaternary and ternary mixtures, with the ternary presenting a smaller thermocline thickness than the solar salt while this parameter is the same considering the quaternary and Hitec XL (R).

Bioethanol steam reforming is one of the most promising route to produce hydrogen from a renewable liquid biofuel. Activity of two Cu-Zn-Al based catalysts was investigated at low temperatures, ranging from 420 to 500 degrees C, in view of temperature limitations associated with solar energy supply by parabolic trough technology. At 450 degrees C the space velocity effect was also investigated, by varying the weight hourly space velocity (WHSV) from 1.67 to 3.32 h(-1). In each experimental conditions, together with the expected hydrogen and carbon dioxide, also methane, ethylene, acetaldehyde and diethylether were detect as products, so indicating the presence of several parallel reaction pathways. A good selectivity to ethanol reforming was obtained only at 500 degrees C (with values of the H-2/CO2 mol ratio of 3.4 and 4.5) with both catalysts, while at lower temperatures alcohol dehydration into acetaldehyde seemed to be the main reaction. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

The Sulphur–Iodine (S-I) thermochemical cycle for hydrogen production from water is one of the widest investigated cycles in the world. Considered the complexity of the S-I process scheme, the focus on chemical characterization of the flowstreams in the loop plant is crucial in order to fully understand chemical equilibriums involved at varying hydriodic acid: (HI:I2) ratio in the mixtures and to determine HI and I2 contents as well. Raman spectroscopy has been widely used to investigate iodine solutions, however few works deals with I2 in HI aqueous mixtures. The aim of the present study is to use Raman spectroscopy for a rapid qualitative and quantitative characterization of the HI–H2O–I2 mixtures involved in the S-I process. At this purpose, Raman spectra of solutions with known HI and I2 concentration have been recorded at varying I2 and HI compositions. It has been found that the chemistry of these solutions is highly dependant on HI:I2 molar ratio. For ratio up to 1:1, the dominant iodine compounds are I3 and its corresponding ion pair HI3. At higher values, close to those of the hydriodic phase HIx of the Bunsen reaction, there is experimental evidence of the formation of higher polyiodine and polyiodides compounds.

The sulphur–iodine thermochemical cycle for hydrogen production has been investigated by ENEA (Agency of New Technologies, Energy and Environment, Italy) over the last 5 years, with a particular focus on chemical aspects. Regarding the hydrogen iodide decomposition, four γ-alumina-supported nickel catalysts were produced and characterized, and then tested in terms of catalytic activity and stability by means of a tubular quartz reactor. In particular, the relationship between catalytic activity and preparation procedure was investigated. From the experimental data acquired, it can be concluded that three of the four catalysts tested demonstrated high catalytic activity, since hydrogen iodide conversion was almost coincident with the theoretical equilibrium value. On the other hand, for all the catalysts, a gradual but considerable deactivation phenomenon was observed at 500 °C, while at a temperature higher than 650 °C the catalytic activity was recovered.

The gaseous hydrogen iodide decomposition is a thermodynamically limited reaction and subsequently a considerable energy expense for the separation and recirculation of the unreacted species is required. In addition the homogeneous gas phase decomposition of hydrogen iodide has a very low rate and the use of a catalytic system, which is generally highly expensive, is necessary. Hence, with the aim of overcoming the bottleneck represented by the hydrogen releasing step of the Sulphur–Iodine (S–I) cycle in terms of costs and process efficiency, in the present work an alternative version of the HI decomposition section (HIx section) is proposed. In that alternative configuration the addition of metallic nickel into the heavy phase coming from Bunsen reaction is conceived in order to quantitatively obtain hydrogen at low temperature. A theoretical and experimental investigation has been performed, a new cycle has been conceived and the resulting energy demand assessed.

In a previous work, it has been studied some Ni-catalysts prepared from different precursors (Ni(C(5)H(7)O(2))(2) and Ni(NO(3))(2)center dot 6H(2)O) via impregnation-calcination or co-precipitation techniques, using commercial gamma-alumina as support. The study pointed out a high initial conversion value for the reaction of hydrogen iodide decomposition at 500 degrees C, but in few hours a progressive deactivation of the catalysts occurred. In order to understand this phenomena, three new catalysts have been prepared starting from Ni(acac)(2),using mesoporous aluminas as support. The initial conversion of HI decomposition with these new catalysts (showing a larger surface area and Ni(0) crystallites on it) was almost coincident with theoretical equilibrium value. Their deactivation at 500 degrees C was slower than that of the catalysts studied in the previous work.

Iodine excess separation from hydriodic acid (HI) is one of the most challenging steps of the Sulfur-Iodine thermochemical water splitting cycle. One promising method is the extraction of HI by using phosphoric acid (H3PO4), with the subsequent separation of gaseous hydriodic acid from water and H3PO4 by a distillation step.The aim of the present work is to provide new experimental liquid-liquid equilibrium data for the biphasic HI/I-2/H2O/H3PO4 quaternary system, varying both temperature and solution composition in order to optimize the excess of anhydrous phosphoric acid to be added. Two temperature levels were tested, i.e. 100 degrees C and 120 degrees C, and the H3PO4 amount was varied in the feed mixture from 7.7% wt to 38% wt while the [I-2]/[HI] and [H2O]/[HI] molar ratios were kept constant at, respectively, a value of 3.7 and 5.6. A temperature level of 120 degrees C, with an H3PO4 initial concentration of about 29% wt leads to the lowest amount of water against HI, which minimizes energy costs in the phosphoric acid reconcentration step, the most energy consuming part in this separation process. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

It is widely agreed that the most energy consuming part of the Sulphur–Iodine (S–I) thermochemical cycle for hydrogen production is represented by separation processes, especially for the HI decomposition section (HIx section). Therefore, the assessment of the real potential of the S–I cycle requires an optimization of the separation sections and, hence, a deep knowledge of the thermodynamic behaviour of the systems to be separated. In this paper, a new thermodynamic model for the electrolyte system HI–H2O–I2 is proposed and validated on vapour–liquid (V–L) equilibrium data at atmospheric pressure. The model provides a reliable description of the phase equilibria of the ternary system and is applied for the flow-sheeting of the HIx section at atmospheric pressure along with the energy assessment of the proposed scheme.

The Sulphur–Iodine thermochemical cycle for hydrogen production has been investigated by ENEA in the framework of the Italian TEPSI Project whose main objective is the realization of an integrated loop plant at a laboratory scale. For the design of the separation–purification equipments, the study of vapour–liquid equilibrium characterization of the ternary HI–H2O–I2 system is considered a key factor. The aim of the present work is to provide new experimental isobaric vapour–liquid equilibrium data for this system by ebulliometry varying both temperature and solution composition. The temperature range has been extended up to about 144°C, the iodine concentration range from 0.2%w/w to 90%w/w while HI weight fraction varies from 4%w/w to 67%w/w in the liquid phase. Most of the data obtained in this work are in good agreement with other experimental data retrieved from literature, which have been recorded in similar operative conditions but acquired by different procedures.

Abstract: The amyloid β‐peptides have been implicated in the excitotoxic mechanism of neuronal injury in the pathogenesis of Alzheimer's disease. In this paper we examine the effect of different amyloid fragments (β A1–40, A1–28, and A25–35), as well as potential neuroprotective compounds on rat cortical neuron viability. Exposure of neurones to β A25–35 or A1–40 at concentrations as low as 1 μg/ml inhibited, significantly, the MTT response and this level of inhibition was similar after 24‐h or three‐day exposure. Furthermore, the level of inhibition was not affected by the presence or absence of 5% horse serum in the medium. Preexposure (10 min) of neurones to ALC at concentrations of 0.1, 1, 5, and 10 mM attenuated the inhibition of the MTT response caused by β A25–35 (50 μg/ml) in serum free medium for 24 h. The treatment of cells with vitamin E (100 μM), catalase (4 mg/ml), NGF (0.1 and 10 ng/ml), or cycloheximide (0.1 μg/ml) significantly restored the MTT response that was inhibited by β A25–35. The mechanism for the protective actions of these compounds against β A25–35 toxicity is not clear but may involve free radical scavenger action and preservation of energy production, although other mechanisms, especially for ALC, such as a direct effect on A‐β interaction with charged anionic phospholipids and/or stabilizing action on membranes, are also possible.

L-Carnitine (L-C) is involved in the transport of acyl groups into mitochondria for beta-oxidation, although its role in the adult brain is still uncertain. We have shown before that the uptake of L-carnitine into cultured rat cortical neurones was dependent on temperature as well as the Na gradient and is inhibited by compounds resembling its structure, like gamma-aminobutyric acid (GABA), but most potently by specific GABA uptake blockers. In this study we have characterised this uptake process further. We have shown that the uptake of L-carnitine may be dependent on Cl ions, in addition to Na ions, but non on Ca ions. The L-C uptake was inhibited by substituent anions in the order gluconate (83%) > isethionate (32%), with propionate being ineffective, whereas GABA uptake was inhibited most potently by propionate substitution (79%) and equally by isethionate and gluconate (67%). This L-C uptake process was not affected by the amino acids, glutamine or lysine, up to 1 mM concentration, although beta-alanine at 500 microM caused a 38% inhibition. The uptake of L-C was also significantly inhibited by structurally-related compounds, with a carbon chain length of three to six atoms, possessing an amine group and/or a carboxyl group. At a concentration of 500 microM, 3-aminopropane sulphonic acid (53%), gamma-butyrobetaine (31%), gamma-hydroxybutyric acid (34%) and 4 methylaminobutyric acid (33%). Other compounds were effective only at the lower concentration of 10 microM, such as butyric acid (25%), nicotinic acid (26%), isonicotinic acid (26%), hexanoic acid (23%) and at 100 microM, like 6-aminocapric acid (22%). Drugs suggested to affect membrane properties, such as chlorpromazine, was without effect at 1 or 10 microM, whereas flunarizine (FLU) at 1 microM inhibited both L-C (24%) and GABA uptake (17%). Other drugs like the cholinesterase inhibitors, tacrine and eserine, also had a small inhibitory effect on L-C uptake, reducing it at 1 microM by 22 and 21% respectively, although higher concentrations were toxic (> 100 microM). Pretreatment of the cells with neuraminidase (50 U ml-1, 10 min) reduced the subsequent uptake of both L-C (18%) and GABA (42%). Hypoxia (3 h) also significantly attenuated L-C uptake (42%), however part of these effects were related to the loss of cell viability. In summary, L-C uptake occurs by a complex mechanism which at least in part may occur by a Na/Cl cotransport mechanism, which could be similar, to that of GABA or may even in part occur via the GABA transporter.

The mechanism for the pathological increase in cell death in various disease states e.g. HIV immunodefficiency or even ageing or Alzheimer's disease, occurs by complex and as yet undefined mechanism(s) related to immunological, virological or biochemical disturbances (i.e. energy depletion, oxidative stress, increased protein degradation). We have studied mitochondrial uncoupling or inhibitor toxicity on neurones at the cellular level and at the mitochondrial level using rhodamine (Rh123) and 10-nonylacridine orange (NAO) fluorescence with confocal microscopy. Blockade of the mitochondrial chain complexes at various points was studied. The possible protective effects of the compound L-carnitine, which plays a central role in mitochondrial function, was tested in this form of neurotoxicity. It appears that L-carnitine and its acetylated form, acetyl-L-carnitine, can attenuate the cell damage, as assessed by lactate dehydrogenase (LDH) release, evoked by the uncoupler, p-(trifluoromethoxy)phenylhdyrazone (FCCP), or by the inhibitors, 3-nitropropionic acid (3-NPA) or rotenone. Further, the FCCP-induced inhibition of Rh123 uptake was antagonized by the preincubation of cells with L-carnitine. Since such neurotoxic mechanisms may be operating in the various pathological forms of myotoxicity and neurotoxicity, these observations suggest potential for a therapeutic approach.

5-Hydroxytryptamine (5-HT), dopamine, oxytocin and melanocortin pathways are known to be involved in the induction of penile erections in rats. Although a dopamine–oxytocin–5-HT link in the central nervous system has been suggested to be important to the control of penile erections, the 5-HT receptor subtype that mediates dopamine–oxytocin–5-HT action and the relationship between the dopamine–oxytocin–5-HT pathway and melanocortin pathway have not been fully elucidated. In this study, in order to clarify these matters, we examined the effects of a selective 5-HT2B/5-HT2C receptors antagonist, 1-(1-methylindol-5-yl)-3-(3-pyridyl)urea (SB200646) and a selective 5-HT2C receptor antagonist, 6-chloro-5-methyl-1-[6-(2-methylpyridin-3-yloxy) pyridin-3-yl carbamoyl] indoline (SB242084) on penile erections induced by a dopamine receptor agonist, 10, 11-dihydroxyaporphine (apomorphine), oxytocin, or a melanocortin receptor agonist, melanotan-II (MT-II) in rats. SB200646 at 10 mg/kg and SB242084 at 3 mg/kg, these doses which completely antagonize penile erections induced by 5-HT2C receptor agonists, m-chlorophenylpiperazine (mCPP) and (S)-2-(7-ethyl-1H-furo[2,3-g]indazol-1-yl)-1-methylethylamine (YM348), significantly inhibited penile erections elicited by apomorphine, oxytocin or MT-II. In addition, in order to clarify further the suggestion that the 5-HT pathway projecting from medulla oblongata to lumbosacral spinal site and lumbosacral 5-HT2C receptor are involved in the induction of penile erection, we also examined the proerectile effect of YM348 in spinal and a 5-HT depletor, p-chlorophenyl alanine (pCPA)-treated rats. YM348 induced intracavernous pressure increase in spinal and pCPA-treated rats as well as normal rats. These results suggest that 5-HT2C receptor in lumbosacral spinal sites mediates not only dopamine–oxytocin–5-HT action but melanocortin action on penile erections, and that the 5-HT pathway is located downstream from melanocortin pathway as well as the dopamine–oxytocin pathway.

The ability of the primary rat cortical cells to take up l-carnitine increased with the age of the cultures and plateaued at around day 11 up to 25 days in vitro (DIV) when a slight decline was evident and by 32 DIV there was a major decrease in l-carnitine uptake. The uptake of l-carnitine displayed complex components. Elimination of mitochondrial energy supply by NaCN (1 mM), rotenone (1.25 μM) and DNP (50 μM), caused a small but significant decrease in the uptake (21, 11 and 16%, respectively). The uptake was highly dependent on the Na gradient, since ouabain (0.5 mM) and Na free buffer (replaced by 250 mM sucrose), reduced uptake by 54 and 63%, respectively. There was competition of l-carnitine uptake by molecules resembling its structure, e.g. γ-aminobutyric acid (GABA), acetyl-l-carnitine (ALC), d-carnitine, l-aminocarnitine and l-choline, with GABA being the most potent inhibitor (57% at 50 μM) and l-choline not being significantly active. The Na-dependent uptake of l-carnitine was saturable with a high Km (692 μM) and Vmax (839 pmol/min/mg). This Na-dependent component was not further additive with the GABA (500 μM) or the DNP (50 μM) inhibitable component, suggesting that it represented the same phenomenon, probably the Na gradient dependent transport of l-carnitine. The results indicate that the uptake of l-carnitine occurs by Na-dependent saturable process as well as non-saturable, Na-independent processes. At least the former uptake mechanism is potently inhibited by GABA.