Modification of Graphene Oxide Membranes by the Incorporation of Nafion Macromolecules and Conductive Scaffolds

Stable, reproducible and low-cost graphene oxide (GO)/Nafion (N) membranes were fabricated using electronically conductive carbon paper (CP) matts as a scaffold. The presence of polar groups in the Nafion molecule facilitates the strong interaction with functional groups in the GO, which increases GO dispersion and aids the retention of the composite into the CP scaffold. Distribution of GO/N was carefully characterized by X-ray diffraction work function measurements, Raman and scanning electron microscopy analyses. The performance of these membranes was tested with 1 M NaCl at standard conditions, finding 85% ion removal in the best membranes by a mixed ion rejection/retention mechanism. The Nafion provided mechanical stability and fixed negative charge to the membranes, and its micellar organization, segregation and confinement favored ion rejection in Nafion-rich areas. The good electronic conductivity of these membranes was also demonstrated, allowing for the application of a small potential bias to enhance membrane performance in future studies.

Direct assembly of thioacid capped quantum dots in solid-state hybrid photovoltaics, effect of QDs size and thermal annealing

The effect of QD size and thermal annealing on water soluble QD solar cells is investigated. CdSe QDs corresponding to the bright-point during synthesis yield the best performance.

Recombination reduction on lead halide perovskite solar cells based on low temperature synthesized hierarchical TiO₂ nanorods

Intensive research on the electron transport material (ETM) has been pursued to improve the efficiency of perovskite solar cells (PSCs) and decrease their cost. More importantly, the role of the ETM layer is not yet fully understood, and research on new device architectures is still needed. Here, we report the use of three-dimensional (3D) TiO2 with a hierarchical architecture based on rutile nanorods (NR) as photoanode material for PSCs. The proposed hierarchical nanorod (HNR) films were synthesized by a two-step low temperature (180 °C) hydrothermal method, and consist of TiO2 nanorod trunks with optimal lengths of 540 nm and TiO2 nanobranches with lengths of 45 nm. Different device configurations were fabricated with TiO2 structures (compact layer, NR and HNR) and CH3NH3PbI3, using different synthetic routes, as the active material. PSCs based on HNR-CH3NH3PbI3 achieved the highest power conversion efficiency compared to PSCs with other TiO2 structures. This result can be ascribed mainly to lower charge recombination as determined by impedance spectroscopy. Furthermore, we have observed that the CH3NH3PbI3 perovskite deposited by the two-step route shows higher efficiency, surface coverage and infiltration within the structure of 3D HNR than the one-step CH3NH3PbI(3-x)Cl(x) perovskite.

Effect of Organic and Inorganic Passivation in Quantum-Dot-Sensitized Solar Cells

The effect of semiconductor passivation on quantum-dot-sensitized solar cells (QDSCs) has been systematically characterized for CdS and CdS/ZnS. We have found that passivation strongly depends on the passivation agent, obtaining an enhancement of the solar cell efficiency for compounds containing amine and thiol groups and, in contrast, a decrease in performance for passivating agents with acid groups. Passivation can induce a change in the position of TiO2 conduction band and also in the recombination rate and nature, reflected in a change in the β parameter. Especially interesting is the finding that β, and consequently the fill factor can be increased with the passivation treatment. Applying this strategy, record cells of 4.65% efficiency for PbS-based QDSCs have been produced.

[Three dimensional anatomy and virtual surgery for transobturator approach]

INTRODUCTION

Stress Urinary Incontinence (SUI) may be managed by transobturator approach. We developed a three-dimensional model, for understanding the surgical anatomy and manual training as well, in order to reduce the learning curve for pelvic surgeries.

OBJECTIVE

To demonstrate in synthetic models, the anatomical basis for the management of SUI and cystocele.

METHOD

The anatomical model includes: pelvic bones, the main layers of the pelvic muscles, ligaments and fascias. The surgical devices were transobturator needles, synthetic slings and meshes for anterior vaginal wall repair. The workshop was carried out with an anatomical overview and hands-on training in this tridimentional models and finally surgery in animals. At the end, a questionnaire was applied to verify the impact of this tool in the learning process and trainee satisfaction.

RESULTS

As far as the anatomical concept, 90% (n=72) of the participants classified this model as very good and 10% (n=8) as good. As a tool for understanding the tridimentional pelvic floor anatomy applied to transobturator procedures there were 100% of approval.

CONCLUSIONS

This synthetic model allows for understanding the pelvic floor tridimentional anatomy and surgical procedures as well. Further skill is got in the animal model reducing the learning curve for transobturator procedures.

Raman and electrochemical impedance studies of sol-gel titanium oxide and single walled carbon nanotubes composite films

Titanium oxide grown by a sol-gel route on single-walled carbon nanotubes was studied by Raman and Electrochemical Impedance techniques and compared with mixtures obtained by mechanical grinding. In spite of the superior dispersion of single-walled carbon nanotubes bundles in sol-gel composites, the lost of the small-diameter carbon nanotubes in the oxidizing sol-gel bath was inferred from their Raman spectra and the lower capacitive current of the voltammograms in 0.1 M H2SO4. We proposed proton electrosorption as the main charge storage mechanism for sol-gel composites, favoured by the hydroxylation and n-type conductivity of the oxide, while electrodes based on mixtures were dominated by double-layer charging, developing some pseudocapacitance with potential cycling due to the reversible oxidation of carbon nanotubes. Comparsion with TiO2/Carbon Blacks composites shows the effective role of single-walled carbon nanotubes as templates to control the mesoporous nature of sol-gel composite electrodes.

Structural and optical properties of highly hydroxylated fullerenes: Stability of molecular domains on the C60 surface

The excitation spectra and the structural properties of highly hydroxylated C(60)(OH)(x) fullerenes (so-called fullerenols) are analyzed by comparing optical absorption experiments on dilute fullerenol-water solutions with semiempirical and density functional theory electronic structure calculations. The optical spectrum of fullerenol molecules with 24-28 OH attached to the carbon surface is characterized by the existence of broad bands with reduced intensities near the ultraviolet region (below approximately 500 nm) together with a complete absence of optical transitions in the visible part of the spectra, contrasting with the intense absorption observed in C(60) solutions. Our theoretical calculations of the absorption spectra, performed within the framework of the semiempirical Zerner intermediate neglect of diatomic differential overlap method [Reviews in Computational Chemistry II, edited by K. B. Lipkowitz and D. B. Boyd (VCH, Weinheim, 1991), Chap. 8, pp. 313-316] for various gas-phase-like C(60)(OH)(26) isomers, reveal that the excitation spectra of fullerenol molecules strongly depend on the degree of surface functionalization, the precise distribution of the OH groups on the carbon structure, and the presence of impurities in the samples. Interestingly, we have surprisingly found that low energy atomic configurations are obtained when the OH groups segregate on the C(60) surface forming molecular domains of different sizes. This patchy behavior for the hydroxyl molecules on the carbon surface leads in general to the formation of fullerene compounds with closed electronic shells, large highest occupied molecular orbital-lowest unoccupied molecular orbital energy gaps, and existence of an excitation spectrum that accounts for the main qualitative features observed in the experimental data.

Evaluación de la función sexual femenina antes y después de un procedimiento para la corrección de la incontinencia urinaria de esfuerzo

The prevalence of urinary incontinence is around 20% of healthy middle-aged women. Incontinence causes a negative impact on the quality of life and sexuality. From August 2002 to January 2004, 30 patients (mean age 43 years) with stress urinary incontinence (59%), overactive bladder (15%) and mixed incontinence (26%) answered the ICIQ-SF(International Consultation on Incontinence Questionnarie-Short Form) and FSFI (Female Sexual Function Index) questionnaires before and after treatment for urinary incontinence. The follow-up ranged from 12 to 53 months. Mean ICIQ score was 17 and 7 before and after treatment respectivelly (p<0,001). Overactive bladder showed the worst scores in all domains. The patients who underwent surgery increased their scores of desire (p=0,02), satisfaction (p=0,05) and total score (p=0,02). Thirteen patients which ICIQ was zero increased: desire (p<0,01), satisfaction (p=0,05) and total score (p=0,01). Urinary incontinence significantly affects the quality of life. Therefore sexual evaluation in incontinence patients is recommended.