Molecular hydrogen affords neuroprotection in a new translational piglet model of hypoxic-ischemic encephalopathy

Summary Perinatal asphyxia (PA) is one of the leading causes of neonatal mortality and morbidity worldwide. Despite the adequate neonatal resuscitation techniques, hypoxic-ischemic encephalopathy (HIE) may develop in survivors. Controlled therapeutic hypothermia (TH) became the gold standard care of asphyxiated babies, but its efficacy to prevent long-term disabilities is limited, therefore, additional neuroprotective interventions are required urgently. The newborn pig is regarded as one of the best models for human PA/HIE pathology and testing putative therapeutic interventions. The best methodology to elicit pathophysiologically/clinically relevant PA insult in animals is still being debated perhaps resulting in some of the failures of alleged neuroprotective therapies in clinical trials. Our major aim was to create a translationally relevant newborn piglet PA/HIE model. Accordingly, we investigated the effects of bilateral carotid artery occlusion (BCAO) on cortical blood flow (CoBF), a routinely applied method in the literature to augment hypoxic stress. Then we developed and extensively characterized our new PA/HIE model of PA/HIE and subsequently tested the neuroprotective potential of molecular H2 in our model. Newborn piglets were anesthetized, instrumented and mechanically ventilated. The effects of BCAO on CoBF were analysed through an implanted cranial window by laser speckle contrast imaging and analysis. PA (6%O2, 20%CO2, 20min) was induced in separate groups of animals to elicit HIE. One group served for testing the effects of H2 administered during reventilation (2.1%H2, 21%O2, 4h) on brain electrical activity, neuronal damage and oxidative stress at 24h survival). BCAO did not reduce CoBF. PA elicited clinically relevant severe alterations in cardiovascular and blood gas/metabolic parameters, resulting in depressed electroencephalogram (EEG), extensive neuronal damage associated with oxidative stress assessed by 8-OHdG immunoreactivity. Molecular H2 facilitated EEG recovery, ameliorated neonatal brain injury and alleviated oxidative stress. In conclusion, our new PA method was able to elicit reproducible, moderate/severe HIE without BCAO. The model was adequate to reveal the neuroprotective effect of molecular H2 administered in a clinically relevant, post-insult time window. The mechanism of neuroprotection appears to involve the reduction of oxidative stress. Encouraged by these promising results, to describe the effect of H2 administration combined with TH remains our future direction

XRD and EDS Investigations of Metal Matrix Composites and Syntactic Foams

Metal matrix composites (MMCs) of different composition were produced and investigated by X-ray diffraction (XRD) and energy dispersive spectrometry (EDS) analysis. Firstly unidirectionally reinforced MMCs were produced using two type carbon fibre reinforcement and commercial purity aluminium matrix. In MMCs the interface layer has significant effect on the mechanical properties of the composites therefore need to be correctly explored. The investigations showed chemical composition changes in the composites, especially at the interface layers. In the case of carbon fibre reinforced composites Al4C3 phase was formed. The amount of Al4C3 depended on the temperature and the time at temperature of the composite during production and on the quality of carbon fibres. As the second investigated MMC, SiC fibre reinforced aluminium matrix composite wires were produced by continuous pressure infiltration. In SiC reinforced MMC wires the effect of interface diffusion was observed. After long term thermal ageing at 300°C alumina was formed and Si and Ti of SiC fibres moved into the matrix. Finally, metal matrix syntactic foams were manufactured which are particle-reinforced composites, but also known as porous materials (foams), because they contain high amount of hollow ceramic microspheres. Four type hollow spheres from different suppliers with different chemical composition and mean diameters were used. In syntactic foams an exchange reaction took place between the aluminium alloy matrix and the Si content of ceramic inclusions. The reaction resulted in significant alumina formation

Manufacturing of Composites by Pressure Infiltration, Structure and Mechanical Properties

This paper presents the possibility of composite block production by using pressure infiltration technology. This method uses the pressure of an inert gas (usually argon or nitrogen) to force the melted matrix material to infiltrate the reinforcing elements. Two types of materials were considered: metal matrix syntactic foam and carbon fibre reinforced metal matrix composite. Physical and mechanical investigations – such as optical microscopy, scanning electron microscopy (SEM), X-ray diffractography (XRD), tensile and upsetting tests (considering aspect ratio) – were performed. The results of measurements are summarized briefly here. Microscopic investigations showed almost perfect infiltration. XRD measurements and tensile tests revealed negative effect of an intermetallic phase (Al(4)C(3)) on ultimate tensile strength (UTS). Syntactic foams showed plateau region in their upsetting diagrams. The effect of aspect ratio was also investigated. Specimens with higher aspect ratios showed higher peak stress and higher modulus of elasticity. In the case of carbon fibre reinforced metal matrix composites Al(4)C(3) ensured high compressive fracture strength

Indiánnak iskolát

A fehér ember megértette, hogy az utolsó indiánok ellen viselt háborút a gyermekek ellen, az iskolákban kell megvívnia. Első lépésben – 1870-től – a rezervá- tumokon létesültek iskolák indi- ánok számára. A gyerekek lakó- helyükhöz közeli intézménybe jártak tanulni, a beiskolázás és a napi jelenlét 6-tól 16 éves korig kötelező, az iskolában használt egyetlen megengedett nyelv az angol. Mivel azonban, és ez hamar kiderült, a gyermekek ezekben a létesítményekben igen közel marad(hat)tak családjukhoz, otthonukhoz, kultú- rájukhoz, az iskola ebben a formájában – tekintve, hogy egyik fő célja a gyerekek indián kultú- rától való megfosztása – nem bizonyult megfelelően hatékonynak

Composite production by pressure infiltration

This paper presents the possibility of composite block production by using pressure infiltration technology. This method uses the pressure of an inert gas (usually argon or nitrogen) to force the melted matrix material to infiltrate the reinforcing elements. Three types of materials were considered: open cell metallic foam, metal matrix syntactic foam and carbon fiber reinforced metal matrix composite. Physical and mechanical investigations – such as SEM and compression tests – were performed. The results of measurements were summarized briefly

The processing and testing of aluminium matrix composite wires, double composites and block composites

The Composite Processing and Testing Laboratory operated for about 15 years in USA. After that, in 2004- 2005, it moved from Boston to the Budapest University of Technology and Economics One of the main results from research and development projects is that of aluminium matrix composite wires produced via continuous processing. The composite wires have experimental applications for the electrically conductive reinforcement of high voltage electric cables, for example. Ceramic continuous-fibre-reinforced MMC-wires were produced with diameters ranging from 0.1 to 2.5 mm and a fibre volume fraction of up to 60% v/o. Thanks to the high efficiency of the continuous process, interface relations are notably reduced, and this increases mechanical properties. The other principal result is one pointing to carbon fibre-reinforced block composites processed by a combination of vacuum and high-pressure infiltration. The result of these processes is fibre-reinforced aluminium matrix composite blocks. Production methods, composite wire reinforced double composites and the results of the material tests of these products are revealed. Various matrixes were made use of in the production of double composites so as to monitor the changes in the interface relations. Alongside the conventional mechanical testing methods, mechanical properties can be characterized by use of an instrumented impact test, while the solidification structure and interfacial properties can have a SEMEDS and thermoelectric measurement (Seebeck-coefficient)