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

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

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

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)

The Morphological Research of the Basalt and Loess Covered Plateaus in the Bakony Mts. (Transdanubian Middle Mts. – Hungary)

 V članku poročamo o morfoloških raziskavah na puhlični planoti Tési in z bazaltom prekritim kraškim območjem v okolici gore Kab na južnem delu gorovja Bakony. Skoraj 600 m visoka gora Kab, prekrita z bazaltom, izstopa iz hribovitega predela južnega dela gorovja Bakony. Površina gore, ki meri kakih 35-40 km², je prekrita z različno debelim bazaltom. Na bazaltnem površju so razvite psevdokraške oblike (depresije), ki so posledica zakrasevanja apnenca pod bazaltom. Z združevanjem glede na morfologijo in hitrost razvoja ter študijem korelacije genetskih značilnosti nastalih združb, smo izluščili nove kraške procese, kjer smo lahko depresije različnih oblik intepretirali kot različne stopnje iste razvojne poti. Mezozojske kamnine planote Tési le redko pogledajo na površje izpod pokrova puhlice. Blizu vrhov so nastajale udorne in ponorne vrtače z zelo omejenim območjem napajanja. Raziskave procesov, oblik in pojavnosti pokritega krasa gore Bakony so pokazale, da je nastanek recentnih jaškov povezan s skritimi litološkimi mejami. Pomembno vlogo pri razvoju površinskih oblik pokritega krasa imajo tudi paleokraški kanali, ki so se reaktivirali še pred nastankom puhlice.   We have conducted our morphological researches on the loess-covered Tési plateau and on the basalt covered karst area around Mt. Kab in the southern part of the Bakony Mts. The nearly 600 m high basalt covered Mt. Kab emerges high from the undulating mountains and hilly areas of the Southern Bakony Mts. Its surface, an area about 35-40 km² is covered by basaltic rocks of different thickness. Pseudokarstic landforms (depressions) developed on the basalt surface due to the karstic corrosion of the buried limestone layers. Grouping the objects of different morphology and evolution rate, and studying in corellation the genetic marks of the significantgroups,a special karst process can be drawn, in which the depressions of various form can be understood as different stations of the same evolutionary series. The Mesosoic rocks building up the 60 km² Tési plateau emerge to the surface rarely above the loess cover. There is agricultural activity on most part of the plateau. Typical covered karstic landforms developed on the 3-5 m thick loess cover. Subsidence dolines or alluvial streamsink dolines with a small catchment area were formed on the summits. We studied the processes, forms and occurrence of recent covered karst of Mt. Bakony, and these studies shows that on the covered karst surface of the Tési-plateau the recent pit formation along with baticapture connected to hidden and real rock boundary, as well as the opening and activation of paleokarstic passages developed before loess formation also play a role in the evolution of the covered karst surface forms of the Tési-plateau