281 research outputs found
Enhanced conductivity of sodium versus lithium salts. Sodium metallacarboranes as electrolyte
[EN] The development of new types of ion conducting materials is one of the most important challenges in the field of energy. Lithium salt polymer electrolytes have been the most convenient, and thus the most widely used in the design of the new generation of batteries. However, in this work, we have observed that Na+ ions provide a higher conductivity, or at least a comparable conductivity to that of Li+ ions in the same basic material. This provides an excellent possibility to use Na+ ions in the design of a new generation of batteries, instead of lithium, to enhance conductivity and ensure wide supply. Our results indicate that the dc-conductivity is larger when the anion is [Co(C2B9H11)(2)](-), [COSANE](-), compared to tetraphenylborate, [TPB](-). Our data also prove that the dc-conductivity behavior of Li+ and Na+ salts is opposite with the two anions. At 40 C-omicron, the conductivity values change from 1.05 x 10(-2) S cm(-1) (Li[COSANE]) and 1.75 x 10(-2) S cm(-1) (Na[COSANE]) to 2.8 x 10(-3) S cm(-1) (Li[TPB]) and 1.5 x 10(-3) S cm(-1) (Na[TPB]). These findings indicate that metallacarboranes can be useful components of mixed matrix membranes (MMMs), providing excellent conductivity when the medium contains sufficient amounts of ionic components and a certain degree of humidity.This research has been supported by the ENE/2015-69203-R and CTQ2013-44670-R projects, granted by the Ministerio de Economia y Competitividad (MINECO), Spain; the Generalitat de Catalunya (2014/SGR/149) and FP7-OCEAN-2013: Proposal number: 614168. C. V. thanks COST CM1302 project. I. F. is enrolled in the PhD program of the UAB.Fuentes, I.; Andrio, A.; Teixidor, F.; Viñas, C.; Compañ Moreno, V. (2017). Enhanced conductivity of sodium versus lithium salts. Sodium metallacarboranes as electrolyte. Physical Chemistry Chemical Physics. 15177(15186):15177-15186. https://doi.org/10.1039/c7cp02526bS15177151861517715186Bakangura, E., Wu, L., Ge, L., Yang, Z., & Xu, T. (2016). Mixed matrix proton exchange membranes for fuel cells: State of the art and perspectives. Progress in Polymer Science, 57, 103-152. doi:10.1016/j.progpolymsci.2015.11.004Lufrano, F., Baglio, V., Staiti, P., Antonucci, V., & Arico’, A. S. (2013). Performance analysis of polymer electrolyte membranes for direct methanol fuel cells. Journal of Power Sources, 243, 519-534. doi:10.1016/j.jpowsour.2013.05.180Jiang, S. P. (2014). Functionalized mesoporous structured inorganic materials as high temperature proton exchange membranes for fuel cells. J. Mater. Chem. A, 2(21), 7637-7655. doi:10.1039/c4ta00121dHeo, Y., Im, H., & Kim, J. (2013). The effect of sulfonated graphene oxide on Sulfonated Poly (Ether Ether Ketone) membrane for direct methanol fuel cells. 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Stabilization of 2,6-Diarylanilinum Cation by Through-Space Cation-pi Interactions
Energetically favorable cation-pi interactions play important roles in numerous molecular recognition processes in chemistry and biology. Herein, we present synergistic experimental and computational physical organic chemistry studies on 2,6-diarylanilines that contain flanking meta/parasubstituted aromatic rings adjacent to the central anilinium ion. A combination of measurements of pK(a) values, structural analyses of 2,6-diarylanilinium cations, and quantum chemical analyses based on the quantitative molecular orbital theory and a canonical energy decomposition analysis (EDA) scheme reveal that through-space cation-pi interactions essentially contribute to observed trends in proton affinities and pK(a) values of 2,6-diarylanilines
Structural and dielectric properties of Cobaltacarborane Composite Polybenzimidazole Membranes as solid polymer electrolytes at high temperature
[EN] The conductivity of a series of composite membranes, based on polybenzimidazole (PBI) containing the metallacarborane salt M[Co(C2B9H11)(2)], M[COSANE] and tetraphenylborate, M[B(C6H5)(4)], M[TPB] both anions having the same number of atoms and the same negative charge, has been investigated. Different cations (M = H+, Li+ and Na+) have been studied and the composite membranes have been characterized by water uptake, swelling ratios, ATR FT-IR, thermogravimetric analysis and electrochemical impedance spectroscopy to explore the dielectric response and ion dynamics in composite membranes. Our results show that conductivity increases with increasing temperature and it is higher for H+ than for Li+ and Na+ for all temperatures under study. The mobility of Li+ is greater in [COSANE](-) than in [TPB](-) composite PBI@membranes while for Na+ it is the opposite. The temperature dependence of the conductivity of the composite was followed by a typical Arrhenius behaviour with two different regions: (1) between 20 and 100 degrees C, and (2) between 100 and 150 degrees C. Using the analysis of electrode polarization (EP) based on the Thrukhan theory we have calculated the ionic diffusion coefficients and the density of carriers. From the double logarithmic plot of the imaginary part of the conductivity (sigma '') versus frequency in the entire range of temperatures studied we have determined for each sample at each temperature, the frequency values of the onset (f(ON)) and full development of electrode polarization (f(MAX)), respectively, which permit us to calculate static permittivity.We gratefully acknowledge Spanish Ministerio de Economia y Competitividad (MINECO) for financial support by the ENE/2015-69203-R project and CTQ2016-75150-R project, and Generalitat de Catalunya (2014/SGR/149). I. Fuentes is enrolled in the PhD program of the UAB. The authors acknowledge Dr Oscar Sahuquillo for technical assistance in TGA.Fuentes, I.; Andrio Balado, A.; Garcia Bernabe, A.; Escorihuela Fuentes, J.; Viñas, C.; Teixidor, F.; Compañ Moreno, V. (2018). Structural and dielectric properties of Cobaltacarborane Composite Polybenzimidazole Membranes as solid polymer electrolytes at high temperature. Physical Chemistry Chemical Physics. 20(15):10173-10185. https://doi.org/10.1039/c8cp00372fS10173101852015I. E. A. Statistics, IEA, Paris, France, 2016Li, W., Dahn, J. R., & Wainwright, D. S. (1994). Rechargeable Lithium Batteries with Aqueous Electrolytes. Science, 264(5162), 1115-1118. doi:10.1126/science.264.5162.1115Lee, H., Yanilmaz, M., Toprakci, O., Fu, K., & Zhang, X. (2014). A review of recent developments in membrane separators for rechargeable lithium-ion batteries. Energy Environ. Sci., 7(12), 3857-3886. doi:10.1039/c4ee01432dAnothumakkool, B., Torris A. 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Helicobacter pylori Dampens HLA-II Expression on Macrophages via the Up-Regulation of miRNAs Targeting CIITA
Macrophages have a major role in infectious and inflammatory diseases, and the available data suggest that Helicobacter pylori persistence can be explained in part by the failure of the bacterium to be killed by professional phagocytes. Macrophages are cells ready to kill the engulfed pathogen, through oxygen-dependent and -independent mechanisms; however, their killing potential can be further augmented by the intervention of T helper (Th) cells upon the specific recognition of human leukocyte antigen (HLA)-II\u2013peptide complexes on the surface of the phagocytic cells. As it pertains to H. pylori, the bacterium is engulfed by macrophages, but it interferes with the phagosome maturation process leading to phagosomes with an altered degradative capacity, and to megasomes, wherein H. pylori resists killing. We recently showed that macrophages infected with H. pylori strongly reduce the expression of HLA-II molecules on the plasma membrane and this compromises the bacterial antigen presentation to Th lymphocytes. In this work, we demonstrate that H. pylori hampers HLA-II expression in macrophages, activated or non-activated by IFN-\u3b3, by down-regulating the expression of the class II major histocompatibility complex transactivator (CIITA), the \u201cmaster control factor\u201d for the expression of HLA class II genes. We provided evidence that this effect relies on the up-regulation of let-7f-5p, let-7i-5p, miR-146b-5p, and -185-5p targeting CIITA. MiRNA expression analysis performed on biopsies from H. pylori-infected patients confirmed the up-regulation of let-7i-5p, miR-146b-5p, and -185-5p in gastritis, in pre-invasive lesions, and in gastric cancer. Taken together, our results suggest that specific miRNAs may be directly involved in the H. pylori infection persistence and may contribute to confer the risk of developing gastric neoplasia in infected patients
Potential application of metallacarboranes as an internal reference: An electrochemical comparative study to ferrocene
Craving and Anxiety Responses as Indicators of the Efficacy of Virtual Reality-Cue Exposure Therapy in Patients Diagnosed with Alcohol use Disorder
Introduction: Virtual Reality (VR) technology has shown promising results as an assessment and treatment instrument in substance use disorders, particularly in attempts to reduce craving. A common application of the VR technology in treatment is based on cue-exposure therapy (CET). Following from previous results, the present case series is part of a larger project aiming to test the efficacy of the Virtual Reality-Cue Exposure Therapy (VR-CET) versus Cognitive-Behavioral Therapy (CBT). Method: Eight patients between ages 40 and 55 (Mage = 49, SD = 5.54) from the Addictive Behaviors Unit at the Hospital Clinic of Barcelona participated in this study after providing written informed consent. Patients were randomly assigned to the VR-CET group (three patients) or the CBT group (five patients). The protocol of the clinical trial consisted of a pre-treatment session (the initial assessment session), six sessions of CBT or VR-CET, and a post-treatment session (post-assessment session). The VR-CET sessions consisted of exposure to alcohol-related cues and environments aiming to reduce anxiety and craving responses to alcohol-related stimuli. The CBT sessions consisted of classical standardized therapy for the treatment of addictions, as previously applied in other clinical trials. In the pre- and post-treatment sessions, patients completed several measures of alcohol craving and anxiety and visual analog scales (VAS) during VR exposure. Results: Our data indicated a significant reduction in both groups in all scores of craving and anxiety responses, as assessed by the different instruments. In addition, the VR-CET group obtained lower scores on anxiety and craving responses than the CBT group. Conclusions: In this ongoing project, the first phase of the clinical trial showed significant improvements in terms of craving and anxiety reduction in both groups, emphasizing that VR-CET can be as efficient as CBT. In addition, patients in the VR-CET group obtained slightly better scores than patients in the CBT group, suggesting the clinical potential of the VR technology in the treatment of substance use disorders. We propose that VR-based CET can be a useful complement to existing treatment methods for AUD patients
Cobaltabis(dicarbollide) ([o-COSAN]−) as Multifunctional Chemotherapeutics: A Prospective Application in Boron Neutron Capture Therapy (BNCT) for Glioblastoma
Purpose: The aim of our study was to assess if the sodium salt of cobaltabis(dicarbollide) and its di-iodinated derivative (Na[o-COSAN] and Na[8,8′-I2-o-COSAN]) could be promising agents for dual anti-cancer treatment (chemotherapy + BNCT) for GBM. Methods: The biological activities of the small molecules were evaluated in vitro with glioblastoma cells lines U87 and T98G in 2D and 3D cell models and in vivo in the small model animal Caenorhabditis elegans (C. elegans) at the L4-stage and using the eggs. Results: Our studies indicated that only spheroids from the U87 cell line have impaired growth after treatment with both compounds, suggesting an increased resistance from T98G spheroids, contrary to what was observed in the monolayer culture, which highlights the need to employ 3D models for future GBM studies. In vitro tests in U87 and T98G cells conclude that the amount of 10B inside the cells is enough for BNCT irradiation. BNCT becomes more effective on T98G after their incubation with Na[8,8′-I2-o-COSAN], whereas no apparent cell-killing effect was observed for untreated cells. Conclusions: These small molecules, particularly [8,8′-I2-o-COSAN]−, are serious candidates for BNCT now that the facilities of accelerator-based neutron sources are more accessible, providing an alternative treatment for resistant glioblastoma
Attentional bias, alcohol craving, and anxiety implications of the virtual reality cue-exposure therapy in severe alcohol use disorder: a case report
Aims: Attentional bias (AB), alcohol craving, and anxiety have important implications in the development and maintenance of alcohol use disorder (AUD). The current study aims to test the effectiveness of a Virtual Reality Cue-Exposure Therapy (VR-CET) to reduce levels of alcohol craving and anxiety and prompt changes in AB toward alcohol content. Method: A 49-year-old male participated in this study, diagnosed with severe AUD, who also used tobacco and illicit substances on an occasional basis and who made several failed attempts to cease substance misuse. The protocol consisted of six VR-CET booster sessions and two assessment sessions (pre- and post-VR-CET) over the course of 5 weeks. The VR-CET program consisted of booster therapy sessions based on virtual reality (VR) exposure to preferred alcohol-related cues and contexts. The initial and final assessment sessions were focused on exploring AB, alcohol craving, and anxiety using paper-and-pencil instruments and the eye-tracking (ET) and VR technologies at different time points. Results: Pre and post assessment sessions indicated falls on the scores of all instruments assessing alcohol craving, anxiety, and AB. Conclusions: This case report, part of a larger project, demonstrates the effectiveness of the VR-CET booster sessions in AUD. In the post-treatment measurements, a variety of instruments showed a change in the AB pattern and an improvement in craving and anxiety responses. As a result of the systematic desensitization, virtual exposure gradually reduced the responses to significant alcohol-related cues and contexts. The implications for AB, anxiety and craving are discussed
Cultural keystone species as a tool for biocultural stewardship. A global review
The cultural keystone species (CKS) concept (i.e. ‘species that shape in a major way the cultural identity of a people’ as defined by Garibaldi and Turner in 2004) has been proposed as part of a common framing for the multiple entangled relationships between species and the socioecological systems in which they exist. However, the blurred and prolific definitions of CKS hamper its univocal application. This work examines the current use of the term CKS to reconcile a definition and explore its practical applications for biocultural stewardship.
We ran a search for the words ‘cultural’ AND ‘keystone’ AND ‘species’. Our search was limited to peer‐reviewed articles published in English between 1994 and 2022 (inclusive) and was conducted using Google Scholar, PubMed, Scopus and Web of Science. We extracted and analysed bibliometric information as well as information on (i) the CKS components, (ii) humans' support for CKS and (iii) the definitions of CKS.
From the 313 selected documents, the CKS concept appears to be increasingly accepted, as evidenced by a growing corpus of literature. However, the absence of a systematic and precise way of documenting CKS precludes global cross‐cultural comparisons.
The geographical distribution of authors using the concept is biased. We found that 47% of all the CKS reported and 38% of the works identified in our review were located in North America.
Beyond ‘supporting identity’, several other of nature's contributions to people are associated with the CKS definitions. However, the contributions of the sociocultural group to the survival and conservation of the CKS (i.e. stewardship) are made explicit only in one‐third of the documents reviewed.
To advance biocultural stewardship as a conservation paradigm, we suggest (a) defining CKS as an indissoluble combination of a non‐human species and one or more sociocultural groups; (b) acknowledging that species and sociocultural group relations should be classified in a continuum, according to gradients of relationship intensity; and (c) explicitly acknowledging the reciprocal relationships between sociocultural groups and species.
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Ion Transport across Biological Membranes by Carborane-Capped Gold Nanoparticles
Carborane-capped gold nanoparticles (Au/carborane NPs, 2-3 nm) can act as artificial ion transporters across biological membranes. The particles themselves are large hydrophobic anions that have the ability to disperse in aqueous media and to partition over both sides of a phospholipid bilayer membrane. Their presence therefore causes a membrane potential that is determined by the relative concentrations of particles on each side of the membrane according to the Nernst equation. The particles tend to adsorb to both sides of the membrane and can flip across if changes in membrane potential require their repartitioning. Such changes can be made either with a potentiostat in an electrochemical cell or by competition with another partitioning ion, for example, potassium in the presence of its specific transporter valinomycin. Carborane-capped gold nanoparticles have a ligand shell full of voids, which stem from the packing of near spherical ligands on a near spherical metal core. These voids are normally filled with sodium or potassium ions, and the charge is overcompensated by excess electrons in the metal core. The anionic particles are therefore able to take up and release a certain payload of cations and to adjust their net charge accordingly. It is demonstrated by potential-dependent fluorescence spectroscopy that polarized phospholipid membranes of vesicles can be depolarized by ion transport mediated by the particles. It is also shown that the particles act as alkali-ion-specific transporters across free-standing membranes under potentiostatic control. Magnesium ions are not transported
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