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1.
Sci Rep ; 12(1): 22594, 2022 12 30.
Artículo en Inglés | MEDLINE | ID: mdl-36585482

RESUMEN

Surgery-related strokes are an important cause of morbidity following resection of high-grade glioma (HGG). We explored the incidence, risk factors and clinical consequences of intra-operative ischemic strokes in surgeries for resection of HGG. We retrospectively followed a cohort of 239 patients who underwent surgical resection of HGG between 2013 and 2017. Tumor types included both isocitrate dehydrogenase (IDH) wildtype glioblastoma and IDH-mutant WHO grade 4 astrocytoma. We analyzed pre- and post-operative demographic, clinical, radiological, anesthesiology and intraoperative neurophysiology data, including overall survival and functional outcomes. Acute ischemic strokes were seen on postoperative diffusion-weighted imaging (DWI) in 30 patients (12.5%), 13 of whom (43%) developed new neurological deficits. Infarcts were more common in insular (23%, p = 0.019) and temporal surgeries (57%, p = 0.01). Immediately after surgery, 35% of patients without infarcts and 57% of those with infarcts experienced motor deficits (p = 0.022). Six months later, rates of motor deficits decreased to 25% in the non-infarcts group and 37% in the infarcts group (p = 0.023 and 0.105, respectively) with a significantly lower Karnofsky-Performance Score (KPS, p = 0.001). Intra-operative language decline in awake procedures was a significant indicator of the occurrence of intra-operative stroke (p = 0.029). In conclusion, intraoperative ischemic events are more common in insular and temporal surgeries for resection of HGG and their intra-operative detection is limited. These strokes can impair motor and speech functions as well as patients' performance status.


Asunto(s)
Neoplasias Encefálicas , Glioma , Accidente Cerebrovascular , Humanos , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/cirugía , Neoplasias Encefálicas/patología , Pronóstico , Estudios Retrospectivos , Glioma/genética , Glioma/cirugía , Glioma/patología , Accidente Cerebrovascular/epidemiología , Accidente Cerebrovascular/etiología , Factores de Riesgo
2.
Sci Rep ; 12(1): 12874, 2022 07 27.
Artículo en Inglés | MEDLINE | ID: mdl-35896589

RESUMEN

Rim restriction surrounding the resection cavity of glioma is often seen on immediate post-op diffusion-weighted imaging (DWI). The etiology and clinical impact of rim restriction are unknown. We evaluated the incidence, risk factors and clinical consequences of this finding. We evaluated patients that underwent surgery for low-grade glioma (LGG) and glioblastoma (GBM) without stroke on post-operative imaging. Analyses encompassed pre- and postoperative clinical, radiological, intraoperative monitoring, survival, functional and neurocognitive outcomes. Between 2013 and 2017, 63 LGG and 209 GBM patients (272 in total) underwent surgical resection and were included in our cohort. Post-op rim restriction was demonstrated in 68 patients, 32% (n = 20) of LGG and 23% (n = 48) of GBM patients. Risk factors for restriction included temporal tumors in GBM (p = 0.025) and insular tumors in LGG (p = 0.09), including longer surgery duration in LGG (p = 0.008). After a 1-year follow-up, LGG patients operated on their dominant with post-op restriction had a higher rate of speech deficits (46 vs 9%, p = 0.004). Rim restriction on postoperative imaging is associated with longer duration of glioma surgery and potentially linked to brain retraction. It apparently has no direct clinical consequences, but is linked to higher rates of speech deficits in LGG dominant-side surgeries.


Asunto(s)
Neoplasias Encefálicas , Glioblastoma , Glioma , Encéfalo/patología , Neoplasias Encefálicas/patología , Neoplasias Encefálicas/cirugía , Glioblastoma/patología , Glioma/patología , Humanos , Pronóstico
3.
Isr Med Assoc J ; 24(4): 253-257, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-35415985

RESUMEN

BACKGROUND: Patients with juvenile myoclonic epilepsy (JME) are especially prone to having antiseizure medications (ASMs) withdrawal seizures (WS). OBJECTIVES: To clarify whether WS in JME patients are caused by a high tendency of non-adherence from seizure-free patients or by a constitutive increased sensitivity to drug withdrawal. METHODS: Epilepsy patients followed in a tertiary epilepsy clinic between 2010 and 2013 were included in the study. WS prevalence was compared between drug-responsive and drug-resistant JME patients and patients with other types of epilepsy. RESULTS: The study included 23 JME patients (16 drug-responsive and 7 drug-resistant) and 138 patients with other epilepsies (74 drug-responsive and 64 drug-resistant). JME patients were younger and included more women than non-JME patients. Significantly more WS were seen in JME than in non-JME patients (P = 0.01) and in the drug-resistant fraction of JME patients in comparison to drug-resistant non-JME patients (P = 0.02). On logistic regression, the type of epilepsy, but not the patient's sex, was found to significantly predict WS. No significant difference was found in the prevalence of WS between drug-responsive and drug-resistant JME patients. The main ASM discontinued in JME was valproic acid (VPA), especially in women. CONCLUSIONS: Our findings suggest a higher sensitivity of JME patients to withdrawal of medications. It is important to educate JME patients about treatment adherence and to explain to their physicians how to carefully reduce or replace ASMs to mitigate the morbidity and mortality related to ASM withdrawal.


Asunto(s)
Epilepsia Mioclónica Juvenil , Síndrome de Abstinencia a Sustancias , Anticonvulsivantes/efectos adversos , Femenino , Humanos , Epilepsia Mioclónica Juvenil/inducido químicamente , Epilepsia Mioclónica Juvenil/tratamiento farmacológico , Convulsiones/tratamiento farmacológico , Convulsiones/epidemiología , Ácido Valproico/efectos adversos
4.
ACS Appl Mater Interfaces ; 13(49): 58532-58538, 2021 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-34870405

RESUMEN

The development of precious group metal-free (PGM-free) catalysts for the oxygen reduction reaction is considered as the main thrust for the cost reduction of fuel cell technologies and their mass production. Within the PGM-free category, molecular catalysts offer an advantage over other heat-treated PGM-free catalysts owing to their well-defined structure, which enables further design of more active, selective, and durable catalysts. Even though non-heat-treated molecular catalysts with exceptional performance have been reported in the past, they were rarely tested in a fuel cell. Herein, we report on a molecular catalyst under alkaline conditions: fluorinated iron phthalocyanine (FeFPc) supported on cheap and commercially available high-surface area carbon─BP2000 (FeFPc@BP2000). It exhibits the highest activity ever reported for molecular catalysts under alkaline conditions in half-cells and fuel cells.

5.
Neuropsychol Rev ; 31(4): 535-568, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-33675457

RESUMEN

RATIONALE: Memory deficits in children with epilepsy have been reported in some but not all studies assessing the effects of side of seizures and resection from the temporal lobe on cognitive performance. This meta-analysis provides a quantitative systematic review of previous studies on this issue. METHOD: A critical review and meta-analysis of the literature on memory performance in children with Temporal Lobe Epilepsy (TLE) was conducted. Search identified 25 studies, 13 of which compared children with TLE to healthy age-matched controls and 12 of which compared children with TLE before and after surgery. RESULTS: Heterogeneity of the comparisons of children with TLE to healthy controls impeded drawing definitive conclusions. However, in 55% of the studies, verbal memory in children with left TLE (LTLE) was impaired as compared to healthy controls. Verbal memory performance slightly declines after pediatric LTLE surgery, but nonverbal memory tasks are not affected. By contrast, verbal memory performance is not affected by pediatric right TLE (RTLE) surgery. CONCLUSIONS: The findings suggest that side of the epileptogenic zone and resection from the temporal lobe affect verbal memory in children with LTLE. Right resection seems to be safe with respect to verbal memory performance.


Asunto(s)
Epilepsia del Lóbulo Temporal , Niño , Epilepsia del Lóbulo Temporal/cirugía , Lateralidad Funcional , Humanos , Imagen por Resonancia Magnética , Trastornos de la Memoria/etiología , Pruebas Neuropsicológicas , Lóbulo Temporal
6.
Neuropsychology ; 34(2): 199-210, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31804104

RESUMEN

OBJECTIVE: To better understand hazard awareness abilities among traumatic brain injury (TBI) survivors of which little is currently known. TBI survivors express degradation in driving abilities, particularly the proactive strategy in which indicators of potentially hazardous situations are sought and identified. The current study examined differences in hazard awareness learning between TBI survivors and noninjured control individuals matched for age and driving experience. METHOD: Forty individuals equally divided among the 2 groups were assessed by exposure to repetitive video-based hazard scenarios, which have been shown to improve hazard awareness in noninjured individuals. Differences in participants' eye movements and behavioral response while watching video clips of genuine traffic scenes were recorded. RESULTS: Although survivors of TBI demonstrated relatively intact hazard awareness abilities under baseline conditions, they failed to learn from repetitive presentation of the same hazardous situation (i.e., they did not improve hazard detection) and thus failed to adjust their scanning and behavioral reaction (e.g., time to reaction, adapt of scanning behavior). Differences were more prominent for hidden hazards. Our results show impoverished anticipation abilities in driving simulation tasks performed in the subacute recovery phase after TBI and that differences in materialized hazards awareness are distinguishable between TBI survivors and noninjured drivers of similar age and driving experience. CONCLUSIONS: Our findings signal the need for further research to clarify the relationship between TBI and hazard awareness training that might be supportive of driving rehabilitation after TBI. (PsycINFO Database Record (c) 2020 APA, all rights reserved).


Asunto(s)
Conducción de Automóvil , Concienciación , Lesiones Traumáticas del Encéfalo/fisiopatología , Adulto , Anciano , Lesiones Traumáticas del Encéfalo/psicología , Medidas del Movimiento Ocular , Movimientos Oculares , Femenino , Humanos , Masculino , Persona de Mediana Edad , Tiempo de Reacción , Grabación en Video , Adulto Joven
8.
Inorg Chem ; 58(14): 8995-9003, 2019 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-31247811

RESUMEN

Recently, we reported on a series of aminomethylene-phosphonate (AMP) analogues, bearing one or two heterocyclic groups on the aminomethylene moiety, as promising Zn(II) chelators. Given the strong Zn(II) binding properties of these compounds, they may find useful applications in metal chelation therapy. With a goal of inhibiting the devastating oxidative damage caused by prion protein in prion diseases, we explored the most promising ligand, {bis[(1H-imidazol-4-yl)methyl]amino}methylphosphonic acid, AMP-(Im)2, 4, as an inhibitor of the oxidative reactivity associated with the Cu(II) complex of prion peptide fragment 84-114. Specifically, we first characterized the Cu(II) complex with AMP-(Im)2 by ultraviolet-visible spectroscopy and electrochemical measurements that indicated the high chemical and electrochemical stability of the complex. Potentiometric pH titration provided evidence of the formation of a stable 1:1 [Cu(II)-AMP-(Im)2]+ complex (ML), with successive binding of a second AMP-(Im)2 molecule yielding ML2 complex [Cu(II)-(AMP-(Im)2)2]+ (log K' = 15.55), and log ß' = 19.84 for ML2 complex. The CuN3O1 ML complex was demonstrated by X-ray crystallography, indicating the thermodynamically stable square pyramidal complex. Chelation of Cu(II) by 4 significantly reduced the oxidation potential of the former. CuCl2 and the 1:2 Cu:AMP-(Im)2 complex showed one-electron redox of Cu(II)/Cu(I) at 0.13 and -0.35 V, respectively. Indeed, 4 was found to be a potent antioxidant that at a 1:1:1 AMP-(Im)2:Cu(II)-PrP84-114 molar ratio almost totally inhibited the oxidation reaction of 4-methylcatechol. Circular dichroism data suggest that this antioxidant activity is due to formation of a ternary, redox inactive Cu(II)-Prp84-114-[AMP-(Im)2] complex. Future studies in prion disease animal models are warranted to assess the potential of 4 to inhibit the devastating oxidative damage caused by PrP.


Asunto(s)
Cobre/química , Isoxazoles/química , Priones/química , Tetrazoles/química , Modelos Moleculares , Oxidación-Reducción , Conformación Proteica
9.
Accid Anal Prev ; 122: 255-267, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-30391702

RESUMEN

Recent evidence shows that compared to experienced drivers, young-inexperienced drivers are more likely to be involved in a crash mainly due to their poor hazard perception (HP) abilities. This skill develops with experience and may be developed through training. We assumed that as any other skill, HP developed through implicit learning. Nevertheless, current training methods, rely on deliberate learning where young-inexperienced drivers are instructed what hazards that they should seek and where they might be located. In this exploratory study, we investigated the effectiveness of a novel training procedure, in which learners were repeatedly exposed to target video clips of driving scenarios embedded within filler scenarios. Each of the target videos included scenarios of either a visible hazard, a hidden materialized hazard or hidden unmaterialized hazard. Twenty-three young-inexperienced drivers and 35 experienced drivers participated in training session followed by a learning transference testing session and 24 additional young-inexperienced drivers participated only in the transference testing session with no training, during which participants were shown novel hazards video clips. Participants responded by pressing a button when they identified a hazard. Eye movement was also tracked using fixations patterns as a proxy to evaluate HP performance. During training, young-inexperienced drivers gradually increased their focus on visible materialized hazards but exhibited no learning curve with respect to hidden hazards. During the learning transference session, both trained groups focused on hazards earlier compared to untrained drivers. These results imply that repetitive training may facilitate HP acquisition among young-inexperienced drivers. Patterns concerning experienced drivers are also discussed.


Asunto(s)
Conducción de Automóvil/educación , Movimientos Oculares/fisiología , Percepción/fisiología , Accidentes de Tránsito/prevención & control , Adulto , Estudios de Casos y Controles , Simulación por Computador , Femenino , Humanos , Masculino , Tiempo de Reacción , Adulto Joven
10.
Adv Mater ; 30(41): e1800406, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-29682822

RESUMEN

One of the most important chemical reactions for renewable energy technologies such as fuel cells and metal-air batteries today is oxygen reduction. Due to the relatively sluggish reaction kinetics, catalysts are necessary to generate high power output. The most common catalyst for this reaction is platinum, but its scarcity and derived high price have raised the search for abundant nonprecious metal catalysts. Inspired from enzymatic processes which are known to catalyze oxygen reduction reaction efficiently, employing transition metal complexes as their catalytic centers, many are working on the development of bioinspired and biomimetic catalysts of this class. This research news article gives a glimpse of the recent progress on the development of bioinspired molecular catalyst for oxygen reduction, highlighting the importance of the molecular structure of the catalysts, from advancements in porphyrins and phthalocyanines to the most recent work on corroles, and 3D networks such as metal-organic frameworks and polymeric networks, all with nonpyrolyzed, well-defined molecular catalysts for oxygen reduction reaction.


Asunto(s)
Materiales Biomiméticos/química , Suministros de Energía Eléctrica , Catálisis , Oxidación-Reducción
11.
Neuropsychol Rev ; 28(1): 16-31, 2018 03.
Artículo en Inglés | MEDLINE | ID: mdl-29079970

RESUMEN

Persons with Mild Cognitive Impairment (MCI) are at high Alzheimer's Disease (AD) risk but the development of sensitive measures to assess subtle cognitive decline in this population poses a major challenge for clinicians and researchers. Eye movement monitoring is a non-invasive, sensitive way to assess subtle cognitive processes in clinical populations. We conducted a critical review and a meta-analysis of the literature on pro and antisaccade paradigm in AD/MCI. The meta-analysis included 20 studies, all of which used the prosaccade paradigm and 13 of which studied the antisaccade paradigm as well. Our meta-analysis showed that AD but not MCI patients showed longer prosaccade latencies when compared to controls. While antisaccade latencies did not differentiate between patients from controls, antisaccade error rate were significantly increased among patients in comparison to controls in over 87% of the studies. These findings highlight antisaccade error rate as a reliable tool to distinguish inhibition abilities between AD/MCI and healthy older persons.


Asunto(s)
Enfermedad de Alzheimer/diagnóstico , Pruebas Neuropsicológicas , Movimientos Sacádicos , Disfunción Cognitiva/diagnóstico , Medidas del Movimiento Ocular , Humanos , Inhibición Psicológica
12.
Chem Commun (Camb) ; 53(96): 12942-12945, 2017 Nov 30.
Artículo en Inglés | MEDLINE | ID: mdl-29155903

RESUMEN

Four ß-pyrrole-substituted cobalt(iii) corroles were studied as electrocatalysts for the oxygen reduction reaction. The results disclose high dependence of the corrole's performance on its substituents, but once adsorbed on a high surface area carbon, this effect vanishes, resulting in a better catalytic performance than most well-defined molecular electrocatalysts for this reaction.

13.
Langmuir ; 32(44): 11672-11680, 2016 11 08.
Artículo en Inglés | MEDLINE | ID: mdl-27728764

RESUMEN

The oxidation level and properties of reduced graphene oxides (rGOs) were fine-tuned using temperature-programmed reductive annealing. rGOs were annealed at different temperatures (from 500 to 1000 °C) in hydrogen to modulate their oxidation levels. The surface of the rGOs was fully characterized using electron paramagnetic resonance backed by Raman, X-ray diffraction, and chemical analysis measurements. These experiments were used to study the changes in the surface of the rGO, its surface functionalities, and its defects as a function of the reduction temperature. In addition, electrochemical measurements to quantify the oxidation level of the rGOs offer a simple tool to correlate the properties of rGOs with their structure. Finally, we explored the effect of different levels of reduction on conductivity, capacitance, and surface reactivity. This research offers simple methodological techniques and routes to control and characterize the oxidation level of bulk quantities of rGO.

14.
Child Neuropsychol ; 22(2): 177-96, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-25495376

RESUMEN

The objective of the current study is to examine the contribution of intellectual abilities, executive functions (EF), and facial emotion recognition to difficulties in Theory of Mind (ToM) abilities in children with a traumatic head injury. Israeli children with a traumatic head injury were compared with their non-injured counterparts. Each group included 18 children (12 males) ages 7-13. Measurements included reading the mind in the eyes, facial emotion recognition, reasoning the other's characteristics based on motive and outcome, Raven's Coloured Progressive Matrices, similarities and digit span (Wechsler Intelligence Scale for Children - Revised 95 subscales), verbal fluency, and the Behaviour Rating Inventory of Executive Functions. Non-injured children performed significantly better on ToM, abstract reasoning, and EF measures compared with children with a traumatic head injury. However, differences in ToM abilities between the groups were no longer significant after controlling for abstract reasoning, working memory, verbal fluency, or facial emotion recognition. Impaired ToM recognition and reasoning abilities after a head injury may result from other cognitive impairments. In children with mild and moderate head injury, poorer performance on ToM tasks may reflect poorer abstract reasoning, a general tendency to concretize stimuli, working memory and verbal fluency deficits, and difficulties in facial emotion recognition, rather than deficits in the ability to understand the other's thoughts and emotions. ToM impairments may be secondary to a range of cognitive deficits in determining social outcomes in this population.


Asunto(s)
Lesiones Encefálicas/psicología , Trastornos del Conocimiento/psicología , Cognición , Comprensión/fisiología , Función Ejecutiva , Teoría de la Mente , Adolescente , Adulto , Estudios de Casos y Controles , Niño , Traumatismos Craneocerebrales/complicaciones , Emociones , Femenino , Humanos , Pruebas de Inteligencia , Masculino , Memoria a Corto Plazo , Persona de Mediana Edad , Pruebas Neuropsicológicas , Índice de Severidad de la Enfermedad , Conducta Social
15.
Angew Chem Int Ed Engl ; 54(47): 14080-4, 2015 Nov 16.
Artículo en Inglés | MEDLINE | ID: mdl-26429211

RESUMEN

The future of affordable fuel cells strongly relies on the design of earth-abundant (non-platinum) catalysts for the electrochemical oxygen reduction reaction (ORR). However, the bottleneck in the overall process occurs therein. We have examined herein trivalent Mn, Fe, Co, Ni, and Cu complexes of ß-pyrrole-brominated corrole as ORR catalysts. The adsorption of these complexes on a high-surface-area carbon powder (BP2000) created a unique composite material, used for electrochemical measurements in acidic aqueous solutions. These experiments disclosed a clear dependence of the catalytic activity on the metal center of the complexes, in the order of Co>Fe>Ni>Mn>Cu. The best catalytic performance was obtained for the Co(III) corrole, whose onset potential was as positive as 0.81 V versus the reversible hydrogen electrode (RHE). Insight into the properties of these systems was gained by spectroscopic and computational characterization of the reduced and oxidized forms of the metallocorroles.

16.
Qual Health Res ; 24(1): 33-45, 2014 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-24214936

RESUMEN

Studies of traditional healers in various cultures describe their initiation into the healing profession as a climax that constructs their professional and personal identity. Literature emphasizes the healers' intense association with the culture in which they work, as reflected in the initiation narratives that healers in various cultures recount. In this article we reveal unique initiation stories and identity formation from Palestinian nonconventional healers in Israel who described a cross-cultural journey: After studying healing traditions of foreign cultures and on returning to their own cultural environment, they developed a unique and complex combination of healing values and traditions. We examine the stories of these healers, whose personal and professional identities are affected by cultural, political, and social contexts. We note the blending of healing traditions and practices, and the changes in identity, assessing them against cultural processes that many Palestinians in Israel have been undergoing over the past few decades.


Asunto(s)
Árabes/psicología , Cultura , Medicina Tradicional/psicología , Femenino , Humanos , Israel , Masculino , Grupos Minoritarios , Investigación Cualitativa , Religión
17.
J Dent Educ ; 77(10): 1270-85, 2013 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-24098031

RESUMEN

The number of adults above sixty-five years of age in the United States will expand considerably over the next thirty years. However, many dentists believe that their dental education did not adequately prepare them to treat an older adult population. Consequently, it is important to review dental curricula to determine where these gaps in education may occur and what can be done to address them in order to improve access to care. In this study, information was gathered from the websites of sixty-two U.S. dental schools in order to understand the types of geriatric courses offered. This review revealed that while most schools (89 percent) provide their predoctoral students with some education in geriatrics, only fourteen (22.6 percent) offer clinical training specifically for older adult care. In addition, forty-three schools (69 percent) include a geriatric component in either their General Practice Residency or Advanced Education in General Dentistry programs or have a certificate program in geriatric dentistry. Only about 23 percent of the schools offer a continuing education course in geriatrics at any one time. Previous studies have shown that clinical training is the most effective method of increasing students' confidence in treating older patients. Consequently, dental schools should work to incorporate clinical experience into geriatric education to prevent widening an existing gap in older adult oral health care.


Asunto(s)
Cuidado Dental para Ancianos , Educación en Odontología , Odontología Geriátrica/educación , Facultades de Odontología , Anciano , Curriculum , Educación en Odontología/estadística & datos numéricos , Educación Continua en Odontología , Educación de Posgrado en Odontología/estadística & datos numéricos , Odontología Geriátrica/estadística & datos numéricos , Humanos , Facultades de Odontología/estadística & datos numéricos , Estados Unidos
18.
J Mater Chem B ; 1(25): 3159-3166, 2013 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-32260916

RESUMEN

The photonic- and redox-triggered cyclic uptake and release of organic substrates in functionalized mesoporous SiO2 nanoparticles (NPs) is demonstrated. The mesoporous SiO2 NPs are functionalized with nitrospiropyran photoisomerizable units. Rhodamine B is encapsulated in the channels of the SiO2 NPs and trapped by the hydrophobic nitrospiropyran capping units. Photoisomerization of the capping units to the protonated nitromerocyanine groups opens the channels and releases the encapsulated dye. Similarly, modification of the SiO2 channels by chloronaphthoquinone units traps eosin Y in the channels, by means of donor-acceptor interactions. The reduction of the quinone units to the chloronaphth hydroquinone donor groups opens the channels and releases the encapsulated substrate. The novelty of the study rests on the demonstration of the reversible and cyclic photostimulated or redox-activated uptake and release of substrates from the mesoporous SiO2 NPs.

19.
J Am Chem Soc ; 132(38): 13220-2, 2010 Sep 29.
Artículo en Inglés | MEDLINE | ID: mdl-20828121

RESUMEN

Electrochemical quartz crystal microbalance (EQCM) technique provides a direct assessment to the behavior of electroadsorbed ions and solvent molecules confined in micropores of activated carbon electrodes in contact with practically important aprotic electrolyte solutions. The estimated value of the solvation number equal to 3 is evident for a partial desolvation of Li(+) cations when adsorbed in carbon micropores.

20.
Nat Mater ; 8(11): 872-5, 2009 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-19838184

RESUMEN

Fast ionic transport in microporous activated-carbon electrodes is a prerequisite for the effective energy storage in electrochemical supercapacitors. However, the quartz-crystal microbalance (QCM), a direct tool to measure ionic fluxes in electrochemical systems, has not yet been used for studying transport phenomena in activated carbons (except for an early report on carbon nanotubes). Conventional electroanalytical and suitable surface and structure-analysis techniques provide limited prognostic information on this matter. It has been demonstrated herein that the QCM response of typical microporous activated carbons can serve as a gravimetric probe of the concentration and compositional changes in their pore volume. This allowed direct monitoring of the ionic fluxes, which depended strongly on the electrode's point of zero change, pore width, ion size and cycling conditions (polarization amplitude, charge/discharge depth and so on). The information on the nature of ionic fluxes into activated carbons is critical for promoting improvements in the performance of electrochemical supercapacitors, membrane technologies and (electro/bio)chemical sensors.

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