Effect of CexZryLazOδ Mixed Oxides on the Structural and Catalytic Behavior of Monometallic Catalytic Converters Under Simulated Exhaust Conditions

The effect of CeO₂, La₂O₃ and ZrO₂ structural stabilizers/promoters, in the form of Ce_xZr_yLa_zO_δ mixed oxides, on the catalytic performance and thermal stability of monometallic (Pt), monolithic-type, Al₂O₃-washcoated three-way catalytic converters (TWCs) was investigated under simulated exhaust conditions. The evolution of textural, structural and surface behavior of Ce_xZr_yLa_zO_δ modified TWCs were identified by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and diffuse reflectance infrared spectroscopy (DRIFTS) and appropriately correlated with the catalytic behavior and thermal stability of TWCs.     

Novel electropositively promoted monometallic (Pt-only) catalytic converters for automotive pollution control

Novel, Pt-only, electropositively promoted by Na, monolithic catalytic converters are developed and tested under simulated exhaust conditions within 150–500 °C. The effects of CeO₂ and La₂O₃ additives on the novel TWC washcoat are also studied. The performance of these simple in constitution, with one precious metal TWCs, was found to be well compared to that of a commercial bimetallic (Pt/Rh)-TWC.     

Three-dimensional weft-knitted textile fabrics-based capacitors

Wearable electronics have evolved from electronic components secured on the human body with straps and belts to partial electronic components integration onto textile structures. Cables and standard components defeat the purpose of the wearable approach by being bulky, rigid and especially not being able to withstand standard textile cleaning/care methods (washing, dry-cleaning, etc.). New 3D textile structures can provide a promising solution. In this research project, we examined the capacitive behaviour of specially prepared 3D weft knitted textile fabrics. The samples knitted specially for this project incorporated conductive outer layers and an insulating inner layer. The outer layers form the plates of the capacitor and the insulating layer plays a role of the dielectric material between the two plates. The structure of these 3D knits allows for inherent capacitive behaviour of the material. These 3D weft-knitted fabrics can be produced on usual existing knitting machines, without any need of dedicated, specialized or expensive equipment. The expected values of the capacitance, based on theoretical calculations, satisfactorily approach the values derived from the measuring process. The ability to customize the structure and hence the capacitance of the 3D fabrics-based capacitors is a positive point towards the design of the textile-based electronics systems in the future. Therefore, the development of textile capacitors based on the 3D fabrics is expected to be an essential contribution to the integration of the wearable system concept.     

Extractives, acidity, buffering capacity, ash and inorganic elements of black locust wood and bark of different clones and origin

Chemical properties of black locust wood and bark from Greece, Bulgaria and Hungary (clones NY, U and J) were investigated. Disks at breast height were taken from 25 black locust trees (five trees per origin and clone) and were divided into separate biomass components (juvenile heartwood, mature heartwood, sapwood and bark). Hot water soluble (HWSE) and dichloromethane soluble extractives (DSE), acidity (pH), buffering capacity, ash content and inorganic elements were determined according to standard laboratory techniques. Bark had the highest extractive content for both HWSE (9.25–13.49%) and DSE (3.09–4.03%). Differences of extractive contents in wood were found to exist between trees of different origin and between the three clones and ranged in heartwood between 5.04–10.10% for HWSE and 0.53–1.83% for DSE and in sapwood between 3.33–6.76% for HWSE and 0.48–1.47% for DSE. The higher values of pH occurred in sapwood (4.92–5.35), while the differences between bark (4.44–5.12) and heartwood (4.35–4.92) were small. Acid (ABC) and base (BBC) buffering capacities from the initial to pH 10 for ABC and to pH 3 for BBC were greater in bark (ABC 0.0172–0.0219 ml/ml and BBC 0.0079–0.0141 ml/ml) than in the other wood components (for heartwood ABC 0.0069–0.0159 ml/ml and BBC 0.0022–0.0096 ml/ml and for sapwood ABC 0.00330.0066 ml/ml and BBC 0.00330.0049 ml/ml). The total ash content was greater in bark (7.24–8.56%) than in other biomass components (for heartwood 0.34–0.89% and for sapwood 0.72–1.24%). The content of the main inorganic elements (Ca, K, Mg, Na, P) were also found to be much higher in bark while sapwood values were greater than heartwood.     

Microstructure changes in mortars attacked by sulphates at 5 °C

In this study mortars have been produced using ordinary Portland cement (CEM I – 32.5) and limestone cement with 15% limestone addition (CEM II/A-LL – 32.5). The mortars were immersed in a solution of 5% Na₂SO₄ at 5 °C for 6 months and the caused deterioration was observed visually at a regular basis. The deterioration product of the surface of both mortars has been identified as thaumasite by the means of XRD, FT-IR, DTA and SEM/EDAX analysis. The damage caused due to formation of thaumasite in both mortars was approximately the same and not influenced by the addition of limestone. Furthermore, expansion and compressive strength of the mortars were studied as a function of time and it was proved they were not influenced by thaumasite formation at the age of 6 months.     

Phenotypic characteristics of cord blood hemopoietic cells

We report a case of T wave alternans in a patient with HIV cardiomyopathy. T wave alternans is an unusual electrocardiographic finding in acquired long QT syndromes that can precede the development of torsades de pointes. Our patient had multiple risk factors for the development of the acquired long QT syndrome, including HIV cardiomyopathy, electrolyte disturbances, and erythromycin therapy. T wave alternans has not been described previously with HIV cardiomyopathy and only rarely with erythromycin therapy. Patients who have HIV cardiomyopathy and who receive intravenous erythromycin may benefit from monitoring for QT prolongation and electrolyte disturbances to avoid the development of torsades de pointes.     

Thermal Aging Behavior of Pt-only TWC Converters Under Simulated Exhaust Conditions: Effect of Rare Earths (CeO2, La2O3) and Alkali (Na) Modifiers

In the present work, the feasibility to design monometallic (Pt-only), low metal loading (0.1 wt% Pt) three-way catalytic converters (TWCs), with comparable catalytic efficiency and thermostability to that of commercial bimetallic Pt/Rh TWCs has been explored. It is shown that this can be accomplished by modifying Pt/??-??l₂O₃ washcoat of TWC via two different methods of promotion: support-mediated promotion by modifying the ??-Al₂O₃ support with rare earth structure-modifiers (CeO₂?CLa₂O₃) and surface-induced promotion by directly modifying the Pt surface with alkalies (e.g., Na), producing a doubly-promoted Pt(Na)/Al₂O₃-(CeO₂?CLa₂O₃) TWC. The catalytic performance of as prepared TWCs in comparison to that of a commercial bimetallic (Pt?CRh) TWC, under simulated exhaust conditions at the stoichiometric point appears to be superior, even after severe thermal treatment at 900 °C for 5 h in air and despite the fact that the latter contain 4.5-fold higher noble metals loading. Moreover, the evolution of structural, textural and surface behavior of aged catalysts was identified by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy and diffuse reflectance infrared Fourier transform spectroscopy and appropriately correlated with the catalytic performance and thermostability of TWCs.     

In situ DRIFTS study of the effect of structure (CeO2–La2O3) and surface (Na) modifiers on the catalytic and surface behaviour of Pt/γ-Al2O3 catalyst under simulated exhaust conditions

The nature and relative populations of adsorbed species formed on the surface of un-promoted and sodium-promoted Pt catalysts supported either on bare Al₂O₃ or CeO₂/La₂O₃-modified Al₂O₃, were investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) under simulated automobile exhaust conditions (CO + NO + C₃H₆ + O₂) at the stoichiometric point. The DRIFT spectra indicate that interaction of the reaction mixture with the Pt/Al₂O₃ catalyst leads mainly to formation of formates and acetates on the support and carbonyl species on partially positively charged Pt atoms (Pt^δ+). Although enrichment of Al₂O₃ with lanthanide elements (CeO₂ and La₂O₃) does not significantly modify the carboxylate species formed on the support, it causes significant modification of the oxidation state of Pt, as indicated by the appearance of a substantial population of carbonyl species on reduced Pt sites (Pt⁰–CO). This modification of the Pt component is enhanced when Na-promotion is used, leading to formation of carbonyl species only on electron enriched Pt (i.e., fully reduced Pt⁰ sites) and to the formation of NCO on these Pt entities (2180 cm⁻¹). The latter are thought to result from enhanced NO dissociation at Na-modified Pt sites. These results correlate well with observed differences in the catalytic performance of the three different systems.