Insights into the Influence of Different Pre-Treatments on Physicochemical Properties of Nafion XL Membrane and Fuel Cell Performance.

Perfluorosulfonic acid (PFSA) polymers such as Nafion are the most frequently used Proton Exchange Membrane (PEM) in PEM fuel cells. Nafion XL is one of the most recently developed membranes designed to enhance performance by employing a mechanically reinforced layer in the architecture and a chemical stabilizer. The influence of the water and acid pre-treatment process on the physicochemical properties of Nafion XL membrane and Membrane Electrode Assembly (MEA) was investigated. The obtained results indicate that the pre-treated membranes have higher water uptake and dimensional swelling ratios, i.e., higher hydrophilicity, while the untreated membrane demonstrated a higher ionic exchange capacity. Furthermore, the conductivity of the acid pre-treated Nafion XL membrane was ~ 9.7% higher compared to the untreated membrane. Additionally, the maximum power densities obtained at 80 °C using acid pre-treatment were ~ 0.8 and 0.93 W/cm2 for re-cast Nafion and Nafion XL, respectively. However, the maximum generated powers for untreated membranes at the same condition were 0.36 and 0.66 W/cm2 for re-cast Nafion and Nafion XL, respectively. The overall results indicated that the PEM's pre-treatment process is essential to enhance performance.

Development of WO3-Nafion Based Membranes for Enabling Higher Water Retention at Low Humidity and Enhancing PEMFC Performance at Intermediate Temperature Operation.

The proton exchange membrane (PEM) represents a pivotal material and a key challenge in developing fuel cell science and hydrogen technology. Nafion is the most promising polymer which will lead to its commercialisation. Hybrid membranes of nanosized tungsten oxide (WO3) and Nafion were fabricated, characterised, and tested in a single cell. The incorporation of 10 wt% WO3 resulted in 21% higher water uptake, 11.7% lower swelling ratio, almost doubling the hydration degree, and 13% higher mechanical stability of the hybrid membrane compared to the Nafion XL. Compared to commercial Nafion XL, the rNF-WO-10 hybrid membrane showed an 8.8% and 20% increase in current density of the cell at 0.4 V operating at 80 and 95 °C with 1.89 and 2.29 A/cm2, respectively. The maximum power density has increased by 9% (0.76 W/cm2) and 19.9% (0.922 W/cm2) when operating at the same temperatures compared to the commercial Nafion XL membrane. Generally, considering the particular structure of Nafion XL, our Nafion-based membrane with 10 wt% WO3 (rNF-WO-10) is a suitable PEM with a comparable performance at different operating conditions.

[Treatment of dystonia by deep brain stimulation: a summary of 40 cases]. / Dystonia kezelése mély agyi stimulációval: 40 eset tapasztalatainak osszefoglalása.

BACKGROUND: Bilateral pallidal deep brain stimulation (DBS) is an established treatment option for primary generalized and segmental dystonia. In the present study we evaluated the results of our dystonia patients treated by DBS. METHODS: The surgical results of forty consecutive dystonia patients underwent DBS implantation were analyzed (age: 43.7 +/- 17.7 years; sex: 22 men; etiology: 24 primary and 16 secondary dystonia; topography: 24 generalized, 12 segmental and four hemidystonia; disease duration: 16.1 +/- 9.3 years). Severity of dystonia measured by Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) and health-related quality of life measured by EQ-5D scale were obtained preoperatively and compared to the scores obtained at postoperative six months and subsequent yearly follow-ups. The average follow-up lasted 2.5 years (median, 0.5-8 years). In all cases the BFMDRS scores were re-evaluated by a rater blinded to the treatment. Treatment responsiveness was defined as an at least 25% improvement on the BFMDRS scores. Non-parametric Mann-Whitney, McNemar and Kruskal-Wallis tests were applied to test statistical significance. RESULTS: Severity of dystonia improved from 31 to 10 points (median, 68% improvement, p < 0.01) in the primary dystonia group, whereas in secondary dystonia these changes were statistically insignificant (improvement from 40 to 31.5 points, 21.2%, p > 0.05). However, the health-related quality of life significantly improved in both groups (primary dystonia: 0.378 vs. 0.788 and secondary dystonia: 0.110 vs. 0.388, p < 0.01). Significantly more patients in the primary dystonia group responded to DBS treatment than those in the secondary dystonia group (83.3% vs. 37.5%, p < 0.01). CONCLUSION: Our results are in accordance with previously published international findings demonstrating that DBS is a highly effective and long-lasting treatment option for primary dystonia. DBS is considerably less efficient in secondary dystonia; however, it still has a high impact on the quality of life presumably due to its pain-relieving effect.

Synergism between constituents of multicomponent catalysts designed for ethanol steam reforming using partial least squares regression and artificial neural networks.

Effects of different catalyst components on the catalytic performance in steam reforming of ethanol have been investigated by means of Artificial Neural Networks (ANNs) and Partial Least Square regression (PLSR). The data base consisted of ca. 400 items (catalysts with varied composition), which were obtained from a former catalyst optimization procedure. Marten's uncertainty (jackknife) test showed that simultaneous addition of Ni and Co has crucial effect on the hydrogen production. The catalyst containing both Ni and Co provided remarkable hydrogen production at 450°C. The addition of Ceas modifier to the bimetallic NiCo catalyst has high importance at lower temperatures: the hydrogen concentration is doubled at 350°C. Addition of Pt had only little effect on the product distribution. The outliers in the data set have been investigated by means of Hotelling T2 control chart. Compositions containing high amount of Cu or Ce have been identified as outliers, which points to the nonlinear effect of Cu and Ce on the catalytic performance. ANNs were used for analysis of the non-linear effects: an optimum was found with increasing amount of Cu and Ce in the catalyst composition. Hydrogen production can be improved by Ce only in the absence of Zn. Additionally, negative cross-effect was evidenced between Ni and Cu. The above relationships have been visualized in Holographic Maps, too. Although predictive ability of PLSR is somewhat worse than that of ANN, PLSR provided indirect evidence that ANNs were trained adequately.