Biomimetic surface imitating microstructure of a lotus leaf cuticle was reproduced synthetically in industrial-grade silicone rubber specimens by means of direct replica method using random templates. The specimens displayed roughness-induced increase of water contact angle and were characterized by static contact angle at 150º superhydrophobic limit. Biomimetic silicone rubber specimens were also tested for prolonged exposure to air corona discharges. Resultant loss of superhydrophobicity was accredited to elimination of microstructural features necessary for roughnessinduced hydrophobicity boost due to physical etching of rough surface by coronagenerated charged ion bombardment.

Rapid, introductory analysis of gases dissolved in insulating oil PGA) carried out in the field can help in effective screening of faulty transformers as well as minimising number of classical laboratory chromatographic DGA tests. It is also crucial for shortening a time gap between oil sampling and its analysis. A novel approach to DGA is presented in this paper. A rapid analysis of oil samples is carried out by means of a portable analyser fitted with electrochemical gas sensors. Extraction of gases from the oil matrix is achieved by means of a dynamic, closedloop stripping process. The analyser, which was built, is controlled by a microprocessor and may be operated in the field as an autonomous device. The system incorporates only two gas sensors and due to an extended set of their output signal wave descriptors used for the analysis it allows for a reliable identification of fault gases present in an oil sample. The identification of basic transformer fault types is illustrated on the basis of analytical results obtained for artificial oil samples prepared in a laboratory as well as those taken from transformers in-operation.

The paper presents a minimal approach to produce superhydrophobic, surface-conducting silicone rubber with a strongly developed surface modified with multiwall carbon nanotubes partially embedded in the silicone elastic matrix. The modification was achieved by physical deposition of carbon nanotube powder on a semi-liquid silicone rubber surface prior to its crosslinking. The resulting biomimetic material displayed superhydrophobic properties (static wetting angle >160°, sliding angle ∼10°), as well as elevated electric surface resistance (surface resistivity approx 18 kΩ). A piezoresistive hysteretic response with nonmonotonic change of the surface resistance accompanying substantial linear stretching was also demonstrated in the developed specimens displaying negative resistance change in a broad range of extension ratios, making them applicable as highly compliant, large-specific-area electrodes.

Ozone, due to its high reactivity cannot be stockpiled, and thus requires to be generated on-demand. The paper reports on laboratory studies of O3 generation in a volume dielectric barrier discharge (DBD) tubular flow-through system with a coaxial-spiral electrode arrangement. Its performance is experimentally verified and compared to a commercial surface DBD O3 source fitted with a three-electrode floating supply arrangement. The presented volume DBD design is capable of steadily producing up to 4180 ppmv O3 at 1 Nl/min unprocessed atmospheric air intake and 10 kV 1.6 kHz sinusoidal high voltage supply corresponding to 67 g/kWh O3 production yield increasing to 93 g/kWh at 100 Nl/min air intake. The effects of high voltage supply tuning are also investigated and discussed together with finite element method simulation results.