Impact and repercussions of the Ostwald-de Izaguirre theory for adsorption from liquid mixtures: A 100-year perspective.

The theory developed in 1922 by Wolfgang Ostwald and Ramón de Izaguirre for adsorption from solution is revisited one hundred years later, with a main focus on its impact and repercussions. A concise historical account is initiated with an examination of the circumstances under which that work was generated. After providing some biographic data about the authors' backgrounds at the time they developed it, a concise description of the so-called Ostwald-de Izaguirre theory is presented. This is followed by an assessment of its impact as a whole in the first decades after it was produced. Starting from about 1960, interest was focused on two separate outcomes from the theory: (i) the first classification of adsorption isotherms ever proposed, and (ii) an equation (Ostwald-de Izaguirre equation) that describes adsorption by solids of binary mixtures of miscible liquids and allows separating the contributions from both components of the solution. Although still in occasional use today, the isotherm classification made by Ostwald and de Izaguirre is of almost exclusively historical interest, having been displaced by Giles' classification. Unlike this, the Ostwald-de Izaguirre equation is still used and, since it derives from a simple mass balance, there is general agreement that no assumptions were made that limit its use. Thus, it seems that there is nothing to prevent the applicability of this equation in the future.

A Simple and Expeditious Route to Phosphate-Functionalized, Water-Processable Graphene for Capacitive Energy Storage.

Phosphate-functionalized carbon-based nanomaterials have attracted significant attention in recent years owing to their outstanding behavior in electrochemical energy-storage devices. In this work, we report a simple approach to obtain phosphate-functionalized graphene (PFG) via anodic exfoliation of graphite at room temperature with a high yield. The graphene nanosheets were obtained via anodic exfoliation of graphite foil using aqueous solutions of H3PO4 or Na3PO4 in the dual role of phosphate sources and electrolytes, and the underlying exfoliation/functionalization mechanisms are proposed. The effect of electrolyte concentration was studied, as low concentrations do not lead to a favorable graphite exfoliation and high concentrations produce fast graphite expansion but poor layer-by-layer delamination. The optimal concentrations are 0.25 M H3PO4 and 0.05 M Na3PO4, which also exhibited the highest phosphorus contents of 2.2 and 1.4 at. %, respectively. Furthermore, when PFG-acid at 0.25 M and PFG-salt at 0.05 M were tested as an electrode material for capacitive energy storage in a three-electrode cell, they achieved a competitive performance of ∼375 F/g (540 F/cm3) and 356 F/g (500 F/cm3), respectively. Finally, devices made up of symmetric electrode cells obtained using PFG-acid at 0.25 M possess energy and power densities up to 17.6 Wh·kg-1 (25.3 Wh·L-1) and 10,200 W/kg; meanwhile, PFG-salt at 0.05 M achieved values of 14.9 Wh·kg-1 (21.3 Wh·L-1) and 9400 W/kg, with 98 and 99% of capacitance retention after 10,000 cycles, respectively. The methodology proposed here also promotes a circular-synthesis process to successfully achieve a more sustainable and greener energy-storage device.

Less iodine injected for the same diagnostic performances: comparison of two low-osmolar contrast agents (iobitridol 350 and iopamidol 370) in coronary angiography and ventriculography: a randomized double-blind clinical study.

OBJECTIVE: Mild reductions in iodine concentration could reduce acute side effects after intraarterial contrast media administration without affecting the quality of coronary artery images. This study was designed to show the equivalence in terms of image quality of two nonionic low-osmolar monomers, iobitridol 350 and iopamidol 370, and to compare their clinical safety in coronary angiography and ventriculography. METHODS AND RESULTS: In this multicentre, double-blind clinical trial, 98 adult patients were randomized to receive either iobitridol 350 or iopamidol 370. The image quality (primary evaluation criterion) of the whole examination was assessed using a 5-point scale (poor, fair, moderate, good, excellent). Secondary endpoints were the image quality per territory, diagnostic efficacy, practical comfort (5-point scale: impossible to evaluate, not practical, moderately practical, practical, very practical to use) and clinical safety (adverse events and vital signs). The proportions of examinations presenting with good or excellent global image quality was similar with both contrast media: 87.8% with iobitridol 350 vs. 89.8% with iopamidol 370. Similar results were observed when considering the image quality specifically for each major coronary artery and left ventricle. No difference between groups was found with respect to other secondary criteria. Adverse events occurred in 7 patients with iobitridol 350 (14.3%) and in 10 patients with iopamidol 370 (20.4%). CONCLUSIONS: This study showed that, with regard to image quality and diagnostic efficacy and using a lower iodine concentration, iobitridol 350 was comparable to iopamidol 370 in adult patients requiring coronary angiography and ventriculography for diagnostic indications.

High Performance Na-O2 Batteries and Printed Microsupercapacitors Based on Water-Processable, Biomolecule-Assisted Anodic Graphene.

Integrated approaches that expedite the production and processing of graphene into useful structures and devices, particularly through simple and environmentally friendly strategies, are highly desirable in the efforts to implement this two-dimensional material in state-of-the-art electrochemical energy storage technologies. Here, we introduce natural nucleotides (e.g., adenosine monophosphate) as bifunctional agents for the electrochemical exfoliation and dispersion of graphene nanosheets in water. Acting both as exfoliating electrolytes and colloidal stabilizers, these biomolecules facilitated access to aqueous graphene bio-inks that could be readily processed into aerogels and inkjet-printed interdigitated patterns. Na-O2 batteries assembled with the graphene-derived aerogels as the cathode and a glyme-based electrolyte exhibited a full discharge capacity of ∼3.8 mAh cm-2 at a current density of 0.2 mA cm-2. Moreover, shallow cycling experiments (0.5 mAh cm-2) boasted a capacity retention of 94% after 50 cycles, which outperformed the cycle life of prior graphene-based cathodes for this type of battery. The positive effect of the nucleotide-adsorbed nanosheets on the battery performance is discussed and related to the presence of the phosphate group in these biomolecules. Microsupercapacitors made from the interdigitated graphene patterns as the electrodes also displayed a competitive performance, affording areal and volumetric energy densities of 0.03 µWh cm-2 and 1.2 mWh cm-3 at power densities of 0.003 mW cm-2 and 0.1 W cm-3, respectively. Taken together, by offering a green and straightforward route to different types of functional graphene-based materials, the present results are expected to ease the development of novel energy storage technologies that exploit the attractions of graphene.

Highly stable performance of supercapacitors from phosphorus-enriched carbons.

Phosphorus-rich microporous carbons (P-carbons) prepared by a simple H(3)PO(4) activation of three different carbon precursors exhibit enhanced supercapacitive performance in 1 M H(2)SO(4) when highly stable performance can be achieved at potentials larger than the theoretical decomposition potential of water. This ability of P-carbons greatly enhances the energy density of supercapacitors that are capable of delivering 16 Wh/kg compared to 5 Wh/kg for the commercial carbon. An intercept-free multiple linear regression model confirms the strongest influence of phosphorus on capacitance together with micropores 0.65-0.83 nm in width that are the most effective in forming the electric double layer.

Aqueous Cathodic Exfoliation Strategy toward Solution-Processable and Phase-Preserved MoS2 Nanosheets for Energy Storage and Catalytic Applications.

The production of MoS2 nanosheets by electrochemical exfoliation routes holds great promise as a means to access this two-dimensional material in large quantities for different practical applications. However, the use of electrolytes based on synthetic organic salts and solvents, as well as issues related to the unwanted oxidation and/or phase transformation of the exfoliated nanosheets, constitute significant obstacles that hinder the industrial adoption of the electrochemical approach. Here, we introduce a safe and sustainable method for the cathodic delamination of MoS2 that makes use of aqueous solutions of very simple and widely available salts, mainly KCl, as the electrolyte. Combined with an appropriate biomolecule-based solvent transfer protocol, such an electrolytic exfoliation route is shown to afford colloidally dispersed, oxide-free, and phase-preserved MoS2 nanosheets of high structural quality in considerable yields. The mechanisms behind the efficient aqueous delamination of the bulk MoS2 cathode are also discussed and rationalized on the basis of the penetration of hydrated cations from the electrolyte between its layers and the immediate reduction of the accompanying water molecules. An asymmetric supercapacitor assembled with a cathodic MoS2 nanosheet-single walled carbon nanotube hybrid as the positive electrode and activated carbon as the negative electrode delivered energy densities (e.g., 26 W h kg-1 at 750 W kg-1 in 6 M KOH) that were competitive with those of other MoS2-based asymmetric devices. When used as a catalyst for the reduction of nitroarenes, the present cathodically exfoliated nanosheets exhibited one of the highest activities reported so far with MoS2 nanostructures, the origin of which is accounted for as well. Overall, by facilitating access to this two-dimensional material through a particularly simple, efficient, and cost-effective technique, these results should expedite the practical implementation of MoS2 nanosheets in energy storage, catalysis, and beyond.

Contralateral Traumatic Hemopneumothorax.

Pneumothorax is the entry of air into the virtual space between the visceral and the parietal pleurae, which can occur spontaneously or to a greater extent in a traumatic way. In daily clinical practice it is frequent to find injuries that generate traumatic pneumothorax that is ipsilateral to the lesion. However, there are case reports of contralateral pneumothorax that occurred in procedures such as insertion of pacemakers, or in cases of pneumonectomy. The following is the case report of a 37-year-old man who was admitted with a sharp wound to the right paravertebral region who developed a left haemopneumothorax due to a tangential course of the injuring agent. Adequate clinical judgment was followed, and several imaging studies were carried out, leading to the diagnosis of traumatic pneumothorax that was contralateral to the described injury.

Aqueous Exfoliation of Transition Metal Dichalcogenides Assisted by DNA/RNA Nucleotides: Catalytically Active and Biocompatible Nanosheets Stabilized by Acid-Base Interactions.

The exfoliation and colloidal stabilization of layered transition metal dichalcogenides (TMDs) in an aqueous medium using functional biomolecules as dispersing agents have a number of potential benefits toward the production and practical use of the corresponding two-dimensional materials, but such a strategy has so far remained underexplored. Here, we report that DNA and RNA nucleotides are highly efficient dispersants in the preparation of stable aqueous suspensions of MoS2 and other TMD nanosheets at significant concentrations (up to 5-10 mg mL-1). Unlike the case of common surfactants, for which adsorption on 2D materials is generally based on weak dispersive forces, the exceptional colloidal stability of the TMD flakes was shown to rely on the presence of relatively strong, specific interactions of Lewis acid-base type between the DNA/RNA nucleotide molecules and the flakes. Moreover, the nucleotide-stabilized MoS2 nanosheets were shown to be efficient catalysts in the reduction of nitroarenes (4-nitrophenol and 4-nitroaniline), thus constituting an attractive alternative to the use of expensive heterogeneous catalysts based on noble metals, and exhibited an electrocatalytic activity toward the hydrogen evolution reaction that was not impaired by the possible presence of nucleotide molecules adsorbed on their active sites. The biocompatibility of these materials was also demonstrated on the basis of cell proliferation and viability assays. Overall, the present work opens new vistas on the colloidal stabilization of 2D materials based on specific interactions that could be useful toward different practical applications.

Impact of Covalent Functionalization on the Aqueous Processability, Catalytic Activity, and Biocompatibility of Chemically Exfoliated MoS2 Nanosheets.

Chemically exfoliated MoS2 (ce-MoS2) has emerged in recent years as an attractive two-dimensional material for use in relevant technological applications, but fully exploiting its potential and versatility will most probably require the deployment of appropriate chemical modification strategies. Here, we demonstrate that extensive covalent functionalization of ce-MoS2 nanosheets with acetic acid groups (∼0.4 groups grafted per MoS2 unit) based on the organoiodide chemistry brings a number of benefits in terms of their processability and functionality. Specifically, the acetic acid-functionalized nanosheets were furnished with long-term (>6 months) colloidal stability in aqueous medium at relatively high concentrations, exhibited a markedly improved temporal retention of catalytic activity toward the reduction of nitroarenes, and could be more effectively coupled with silver nanoparticles to form hybrid nanostructures. Furthermore, in vitro cell proliferation tests carried out with murine fibroblasts suggested that the chemical derivatization had a positive effect on the biocompatibility of ce-MoS2. A hydrothermal annealing procedure was also implemented to promote the structural conversion of the functionalized nanosheets from the 1T phase that was induced during the chemical exfoliation step to the original 2H phase of the starting bulk material, while retaining at the same time the aqueous colloidal stability afforded by the presence of the acetic acid groups. Overall, by highlighting the benefits of this type of chemical derivatization, the present work should contribute to strengthen the position of ce-MoS2 as a two-dimensional material of significant practical utility.

From graphene oxide to pristine graphene: revealing the inner workings of the full structural restoration.

High temperature annealing is the only method known to date that allows the complete repair of a defective lattice of graphenes derived from graphite oxide, but most of the relevant aspects of such restoration processes are poorly understood. Here, we investigate both experimentally (scanning probe microscopy) and theoretically (molecular dynamics simulations) the thermal evolution of individual graphene oxide sheets, which is rationalized on the basis of the generation and the dynamics of atomic vacancies in the carbon lattice. For unreduced and mildly reduced graphene oxide sheets, the amount of generated vacancies was so large that they disintegrated at 1773-2073 K. By contrast, highly reduced sheets survived annealing and their structure could be completely restored at 2073 K. For the latter, a minor atomic-sized defect with six-fold symmetry was observed and ascribed to a stable cluster of nitrogen dopants. The thermal behavior of the sheets was significantly altered when they were supported on a vacancy-decorated graphite substrate, as well as for the overlapped/stacked sheets. In these cases, a net transfer of carbon atoms between neighboring sheets via atomic vacancies takes place, affording an additional healing process. Direct evidence of sheet coalescence with the step edge of the graphite substrate was also gathered from experiments and theory.

Role of hydration in contrast-induced nephropathy in patients who underwent primary percutaneous coronary intervention.

To investigate the role of hydration to prevent contrast-induced nephropathy (CIN) in patients with ST-segment elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PPCI), we prospectively included 408 consecutive patients who were randomly assigned to receive either hydration with isotonic saline (1 ml/kg/h since the beginning of the procedure and for 24 hours after it: NS+ group) or not (NS- group). All patients received an iso-osmolar nonionic contrast medium. The primary end point was the development of CIN: ≥25% or ≥0.5 mg/dl increase in serum creatinine within 3 days after the procedure. CIN was observed in 14% of patients: 21% in the NS- group and 11% in the NS+ group (p=0.016). CIN was significantly associated with death (15.2% vs 2.8%; p<0.0001) and need for dialysis (13.4% vs 0%; p<0.0001). In multivariate analysis, the only predictors of CIN were hydration (OR=0.29 [0.14 to 0.66]; p=0.003) and the hemoglobin before the procedure (OR=0.69 [0.59 to 0.88]; p<0.0001). In conclusion, intravenous saline hydration during PPCI reduced the risk of CIN to 48%. Patients with CIN had increased mortality and need for dialysis. Given the higher incidence of CIN in emergent procedures, and its morbidity and mortality, preventive hydration should be mandatory in them unless contraindicated.

Thrombotic occlusion of the left main coronary artery during coronary angiography.

A case of left main occlusion due to thrombus during coronary angiography is reported. This rare and extremely dangerous complication was successfully managed with resuscitation maneuvers, hemodynamic support, urgent balloon angioplasty plus stent implantation, anticoagulation with heparin and potent therapy directed at preventing platelet aggregation. The thrombus most likely detached from the arterial sheath, although coexisting circumstances, such as the use of non-ionic contrast or a transient hypercoagulable state, may have had an influence. A careful technique during the procedure is probably the most effective preventive measure.

Carbon molecular sieves for air separation from Nomex aramid fibers.

Activated carbon fibers prepared from aramid fibers have proved to possess outstanding homogeneity in pore size, most of all when Nomex aramid fiber is used as precursor. Taking advantage of this feature, microporous carbon molecular sieves for air separation have been prepared through carbon vapor deposition of benzene on Nomex-derived carbon fibers activated to two different burnoff degrees. Carbon molecular sieves with good selectivity for this separation and showing acceptable adsorption capacities were obtained from ACFs activated to the two burnoff degrees chosen.

Adsorption of n-alkanes on plasma-oxidized high-strength carbon fibers.

The objective of this work was to characterize the degree of heterogeneity brought about by oxygen plasma treatment of carbon fibers by studying its effects on the adsorption of n-alkanes. Untreated and unsized high-strength carbon fibers were subjected to oxygen plasma treatments with different degrees of severity. A sample of the same material oxidized following a standard industrial method was also studied for comparison. Adsorption of C5-C10n-alkanes at 303-353 K was measured by inverse gas chromatography (IGC). Elution peaks were symmetrical for the fresh and industrially oxidized samples; however, a large extent of asymmetry was observed for the plasma-treated fibers. Differences in surface heterogeneity were quantified in terms of several adsorption thermodynamic magnitudes. Differential heats of adsorption exhibited values similar to those corresponding to the probe-basal plane interaction. The dispersive component of the surface tension of the solids increased clearly upon plasma oxidation, the increase being systematic according to the severity of plasma treatment. It can be concluded that plasma oxidation generates high-surface-energy sites responsible for trapping of n-alkane molecules, this effect being more marked as the chain length increases. The possibility of this effect being associated to creation of micropores was ruled out on the basis of volumetric CO2 adsorption experiments and IGC measurements at finite dilution. Scanning tunneling microscopy observations allowed us to establish a possible connection between fiber surface nanostructure and IGC results. The sites accessible to n-alkane molecules in the industrially oxidized sample seem to be highly disordered, thus leading to a weaker interaction with the adsorbate.

Direct stenting in single coronary artery arising from the left sinus of Valsalva--a case report.

A patient with postinfarction angina was referred for coronary angiography. In addition to severe atherosclerotic coronary disease, which was responsible for clinical presentation, a single coronary artery arising from the left sinus of Valsalva was found. The authors report the use of direct coronary stent deployment without predilation to treat disease in this rare anomaly.

[Complications with femoral access in cardiac cathetization. Impact of previous systematic femoral angiography and hemostasis with VasoSeal-ES collagen plug]. / Complicaciones del acceso femoral en el cateterismo cardíaco: impacto de la angiografía femoral sistemática previa y la hemostasia con tapón de colágeno VasoSeal-ES.

INTRODUCTION AND OBJECTIVES: Most cardiac catheterizations are performed via femoral artery access, and hemostatic devices are commonly used. We evaluate the relationship between the strategy used for femoral arteriography and the use of VasoSeal-ES, and local vascular complications. PATIENTS AND METHOD: Prospective study of 540 consecutive catheterizations with systematic femoral artery and sheath angiography. VasoSeal-ES was used in 427 patients. Predictors of local vascular complications such as patient-related factors, anatomy and hemostasis were analyzed. Variables related to failure of the collagen plug were also studied. RESULTS: Punctures of the common femoral artery occurred in 35.9% of all patients (16% in the deep femoral artery and its ostium). Spasm was evident in 18% (ranging from 58.1% in the deep femoral artery to 5.2% in the common femoral artery). Puncture at the site of ramification was seen in 11.3%. Angiographically significant atheroma was seen in 17.8%. The femoral head was a valid landmark for the common femoral artery in only 63.9% of the pateints. Risk factors for local vascular complications were punctures of the common femoral artery, female sex and failure of VasoSeal-ES to achieve hemostasis (15.8% in the first two months of use, 5.2% in the last months of the study). Complications involving superficial and deep femoral arteries occurred in 6.7% and 1.2% of the patients, respectively, in contrast to 0.6% involving the common femoral artery. Variables related to collagen plug failure were patient-related factors, weight less than 55 kg, operator-related factors and the learning curve. CONCLUSIONS: Systematic femoral angiography provides data that aids the choice of the best hemostasis procedure to reduce local vascular complications. Punctures of the common femoral artery were more frequent than expected, and were associated with a higher complication rate. VasoSeal-ES is a safe and useful method of hemostasis, and its infrequent failures were associated with high complication rates that were substantially reduced with experience.

Influence of porous texture and surface chemistry on the CO2 adsorption capacity of porous carbons: acidic and basic site interactions.

Doped porous carbons exhibiting highly developed porosity and rich surface chemistry have been prepared and subsequently applied to clarify the influence of both factors on carbon dioxide capture. Nanocasting was selected as synthetic route, in which a polyaramide precursor (3-aminobenzoic acid) was thermally polymerized inside the porosity of an SBA-15 template in the presence of different H3PO4 concentrations. The surface chemistry and the porous texture of the carbons could be easily modulated by varying the H3PO4 concentration and carbonization temperature. Porous texture was found to be the determinant factor on carbon dioxide adsorption at 0 °C, while surface chemistry played an important role at higher adsorption temperatures. We proved that nitrogen functionalities acted as basic sites and oxygen and phosphorus groups as acidic ones toward adsorption of CO2 molecules. Among the nitrogen functional groups, pyrrolic groups exhibited the highest influence, while the positive effect of pyridinic and quaternary functionalities was smaller. Finally, some of these N-doped carbons exhibit CO2 heats of adsorption higher than 42 kJ/mol, which make them excellent candidates for CO2 capture.

Chemically exfoliated MoS2 nanosheets as an efficient catalyst for reduction reactions in the aqueous phase.

Chemically exfoliated MoS2 (ce-MoS2) nanosheets that incorporate a large fraction of metallic 1T phase have been recently shown to possess a high electrocatalytic activity in the hydrogen evolution reaction, but the potential of this two-dimensional material as a catalyst has otherwise remained mostly uncharted. Here, we demonstrate that ce-MoS2 nanosheets are efficient catalysts for a number of model reduction reactions (namely, those of 4-nitrophenol, 4-nitroaniline, methyl orange, and [Fe(CN)6](3-)) carried out in aqueous medium using NaBH4 as a reductant. The performance of the nanosheets in these reactions is found to be comparable to that of many noble metal-based catalysts. The possible reaction pathways involving ce-MoS2 as a catalyst are also discussed and investigated. Overall, the present results expand the scope of this two-dimensional material as a competitive, inexpensive, and earth-abundant catalyst.

Post-resuscitation electrocardiograms, acute coronary findings and in-hospital prognosis of survivors of out-of-hospital cardiac arrest.

BACKGROUND: Identification of acute coronary lesions amenable to urgent intervention in survivors of out-of-hospital cardiac arrest is crucial. We aimed to compare the clinical and electrocardiographic characteristics to urgent coronary findings, and to analyze in-hospital prognosis of these patients. METHODS: From January 2005 to December 2012 we retrospectively identified consecutive patients resuscitated from out-of-hospital cardiac arrest, and analyzed the clinical characteristics, post-resuscitation electrocardiogram and coronary angiogram of those who underwent emergent angiography. Mortality and neurologic status at discharge were also assessed. RESULTS: Patients with ST-elevation more frequently had obstructive coronary artery disease (89% vs. 51%, p<0.001) or acute coronary occlusions (83% vs. 8%, p<0.001) than patients without ST-elevation. Independent predictors of an acute coronary occlusion were chest pain before arrest (OR 0.16, 95% CI 0.04-0.7, p=0.01), a shockable initial rhythm (OR 0.16, 95% CI 0.03-0.9, p=0.03), and ST-elevation on the post-resuscitation electrocardiogram (OR 0.02, 95% CI 0.004-0.13, p<0.001). Survival with favorable neurologic recovery at discharge was 59%. Independent predictors of mortality or unfavorable neurological outcome at discharge were absence of basic life support (OR 0.2, 95% CI 0.06-0.9, p=0.04), prolonged resuscitation time (OR 0.9, 95% CI 0.8-0.9, p=0.01), and necessity of vasopressors (OR 14.8, 95% CI 3.3-65.4, p=0.001). CONCLUSIONS: Most patients with ST-elevation on the post-resuscitation electrocardiogram had an acute coronary occlusion, as opposed to patients without ST-elevation. Absence of basic life support, prolonged resuscitation time and use of vasopressors were independent predictors of worse in-hospital outcome.

Energy storage on ultrahigh surface area activated carbon fibers derived from PMIA.

High-performance carbon materials for energy storage applications have been obtained by using poly(m-phenylene isophthalamide), PMIA, as a precursor through the chemical activation of the carbonized aramid fiber by using KOH. The yield of the process of activation was remarkably high (25-40 wt%), resulting in activated carbon fibers (ACFs) with ultrahigh surface areas, over 3000 m(2) g(-1) , and pore volumes exceeding 1.50 cm(3) g(-1) , keeping intact the fibrous morphology. The porous structure and the surface chemical properties could easily be controlled through the conditions of activation. The PMIA-derived ACFs were tested in two types of energy storage applications. At -196 °C and 1 bar, H2 uptake values of approximately 3 t% were obtained, which, in combination with the textural properties, rendered it a good candidate for H2 adsorption at high pressure and temperature. The performance of the ACFs as electrodes for electrochemical supercapacitors was also investigated. Specific capacitance values between 297 and 531 g(-1) at 50 mA g(-1) were obtained in aqueous electrolyte (1 H2 SO4 ), showing different behaviors depending on the surface chemical properties.