Measurement the thermal profile of steelmaking ladle with subsequent evaluation the reasons of lining damage

Based on the operational measurement, of which content was to determine ladle thermal profile, there were analysed causes of possible damage of lining in steel ladles by steel breakout through the ladle shell. There exists connection between thermal state of ladle lining during the operation and its lifetime. There were reached to the conclusion that the cause of failure in the lining of ladle is except for high temperature of bath, also wide interval of temperature change during the tap operation, in consequence with possible insufficient pre-heating of ladle, discontinuous operation of aggregate and damage of insulating lining layer, respectively deformation of ladles shell.Web of Science61128227

Hydraulic properties of ladle slags

The article presents results of examining of hydraulic properties of ladle slags formed during production of steel. The studied ladle slags were subjected to different cooling mode from the molten state. Based on the ability of the slag react with the water was assessed their hydraulic activity. The hydraulic properties are caused by the presence of minerals dicalcium silicate, tricalcium aluminate, mayenite, brownmillerite and dicalcium ferite. The emergence of required hydrating phases in the ladle slags is conditioned by a sufficient CaO content and their cooling rate. The contact the slag with water during processing and their ageing has a negative effect. The experiment has shown that the phase transformation of the mineral dicalcium silicate which occurs during cooling of the ladle slags cause their volume instability.Web of Science55340239

Idegi plaszticitás és neuroprotekció lehetőségeinek kutatása triptofán metabolitokkal és származékaikkal = Neuronal plasticity and neuronal protection - research with triptophan-metabolites and conjugates

A pályázati támogatás olyan neuroprotekciós eljárások, anyagok kidolgozását szolgálta, mely ischemiás állapotok, traumák után fellépő hiperexcitáció csökkentésével mérsékli az ilyenkor fellépő másodlagos sejtpusztulást. A triptofán egyik metabolitja a kinurénsav (KYNA), mely az NMDA receptorok természetes inhibitoraként viselkedik a NMDA receptorokhoz kapcsolódva. A KYNA azonban nem megy át a vér-agy gáton, viszont előanyaga a kinurenin (KYN) igen. Kidolgoztunk egy módszert, melyben a KYN-t (300 mg/kg, i.p.) probeneciddel (PROB, 200 mg/kg, i.p.) együtt adva, oly mértékig meg tudjuk emelni a KYNA szintet az agyban, hogy az hatékonyan képes gátolni az agyi sérüléseket követő hiperexcitációt. Ezzel a módszerrel hatékony neuroprotekciót értünk el focalis és globalis agyi ischemiában, pentylentetrazollal (PTZ) kiváltott görcstevékenységben, de még migrén modellben is. Kifejlesztettünk két további kinurénsav származékot, a glukozamin-kinurénsavat (KYNA-NH-GLUC) és az SZR-72-nek nevezett szert, melyek szintén hatékony neuroprotektív anyagok, ugyanakkor átjutnak a vér-agy gáton, tehát szisztémásan is adhatók. Kísérleti körülmények között tehát hatékony neuroprotektív eljárást dolgoztunk ki, és hatékony anyagokat állítottunk elő. Továbbá, kimutattuk a KYNA-ról, hogy Janus-arcú, mert gátló hatása mellett, amit ?M-os koncentrációban fejt ki, ennél jóval alacsonyabb koncentrációban (200-250 nM) serkentő hatású. Mindez felveti a KYNA lehetséges neuromodulátor szerepét. | The aim of this project was to develop neuroprotective agents and protocols, which are able to reduce the late neuronal death following ischemic brain attack or brain trauma. The kynurenine pathway converts tryptophan into various compounds, including L-kynurenine (KYN), which in turn can be converted into the excitatory amino acid receptor (namely NMDA receptor) antagonist kynurenic acid (KYNA). The use of KYNA as a neuroprotective agent is rather restricted, however, because KYNA has only a very limited ability to cross the blood-brain barrier. In contrast, KYN crosses this barrier more readily. We have developed a protocol in which KYN (300 mg/kg, i.p.) administration together with probenedid (PROB, 200 mg/kg, i.p.), an organic acid transport blocker, led to significant neuroprotection in both focal and global brain ischemia, in traumatic brain attack, in migraine, and led to the inhibition of pentylenetetrazole (PTZ)-induced seizures. In addition, we have developed two kynurenic acid derivatives; glucosamine-kynurenic acid (KYNA-NH-GLUC) and SZR-72. Both of them cross the blood-brain barrier easily, and are neuroprotective agents. In addition to these experimental results, we have shown that KYNA is a Janus-faced agent, which in ?M concentration behaves as a neuroinhibitor, while in nM concentration, it stimulates the neuronal activity. This result suggests that KYNA might be play a role of a neuromodulator in the central nervoussystem

The corrosion effect of fly ash from biomass combustion on andalusite refractory materials

The main problem affecting the life of refractory linings in furnaces is alkaline corrosion formed during biomass combustion, especially in systems with SiO2–Al2O3 . This corrosion effect is very intensive compared to using conventional technologies designed for burning traditional fuels. This study focuses on the development of a new type of andalusite refractory material with a higher corrosion resistance to K2CO3 and fly ash after biomass combustion. The original andalusite refractory material is labeled A60PT0, with an oxide content of 60 wt.% Al2O3 and 37 wt.% SiO2 , a compressive strength parameter of 64 MPa, and an apparent porosity of 15%. In the experiment, four mixtures (labeled A60PT1–A60PT4) were modified primarily using the raw materials and granulometry. The fly ash was characterized by an X-ray diffraction analysis with the following phases: quartz, calcite, microcline, leucite, portlandite, and hematite. According to the X-ray fluorescence analysis, the samples contained the following oxides: 47 wt.% CaO, 12 wt.% K2O, 4.6 wt.% SiO2 , 3.5 wt.% MgO, and some minority oxides such as P2O5 , MgO, MnO, and Fe2O3 between 2 and 5 %. The tendency for slagging/fouling of the ash was determined with the help of the indexes B/A, TA, Kt , and Fu. The final material was a shaped andalusite refractory material labeled A60PT4 with a content of 65 wt.% Al2O3 and 36 wt.% SiO2. The properties of the andalusite material were a compressive strength of 106.9 MPa, an apparent porosity of 13%, and the recommended temperature of use up to 1300 ◦C. For corrosion testing, a static crucible test was performed according to the norm CSN CEN/TS 15418 and ˇ the company’s internal regulation. The exposure time of the samples was 2 h and 5 h at temperatures of 1100 ◦C and 1400 ◦C for K2CO3 and ash, respectively. For the evaluation of tested samples, an X-ray powder differential analysis, an X-ray fluorescence analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used.Web of Science133art. no. 35

Corrosive effect of wood ash produced by biomass combustion on refractory materials in a binary Al-Si system

In terms of its chemical composition, biomass is a very complex type of fuel. Its combustion leads to the formation of materials such as alkaline ash and gases, and there is evidence of the corrosive effect this process has on refractory linings, thus shortening the service life of the combustion unit. This frequently encountered process is known as "alkaline oxidative bursting". Corrosion is very complex, and it has not been completely described yet. Alkaline corrosion is the most common cause of furnace-lining degradation in aggregates that burn biomass. This article deals with an experiment investigating the corrosion resistance of 2 types of refractory materials in the Al2O3-SiO2 binary system, for the following compositions: I. (53 wt.% SiO2/42 wt.% Al2O3) and II. (28 wt.% SiO2/46 wt.% Al2O3/12 wt.% SiC). These were exposed to seven types of ash obtained from one biomass combustion company in the Czech Republic. The chemical composition of the ash is a good indicator of the problematic nature of a type of biomass. The ashes were analyzed by X-ray diffraction and X-ray fluorescence. Analysis confirmed that ash composition varies. The experiment also included the calculation of the so-called "slagging/fouling index" (I/C, TA, Sr, B/A, Fu, etc.), which can be used to estimate the probability of slag formation in combustion units. The corrosive effect on refractory materials was evaluated according to the norm CSN P CEN/TS 15418, and a static corrosion test was used to investigate sample corrosion.Web of Science1516art. no. 579

Neuroprotective effects of repeated transient global ischemia and of kynurenine adminsitration induced by four-vessel occlusions on hippocampal CA1 neurons.

The hippocampal CA1 subfield is a brain region that is particularly sensitive to hypoxia. Although this subfield is selectively vulnerable to ischemic injuries manifested in delayed neuronal death (DND), the mechanism leading to neuronal degeneration is not fully understood. Burda recently reported that a second pathophysiological stress, applied within a suitable time, offers an opportunity for salvaging neurons in the CA1 region against DND (Neurochem. Res., 30: 1397-1405, 2005). In our study, NeuN immunohistochemistry was applied to detect survival CA1 neurons, while Fluoro-Jade B staining was used to evaluate the number of injured neurons after interventions resulting in transient global ischemia. Four groups of animals were used: 1: intact controls; 2: sham controls (2 vertebral arteries coagulated (2VAC), but 2 carotids sham-operated); 3: 2VAC + 2 carotids occluded (2CA) for 10 min; 4: 2VAC + 2CA (10 min) + 2 days later, a repeated 2CA (5 min). In group 3 (2VAC + 2CA (10 min)), marked cell destruction was found in the CA1 subfield: only 36.4% of the CA1 neurons survived. However, in group 4 (5-min second ischemic insult), the proportion of surviving cells in the CA1 region was 59.3%. There was no significant difference in CA1 cell loss between groups 1 and 2. Our findings suggest that the second ischemic stress, 2 days after the first ischemia induced by 2VAC + 2CA can be efficient in the prevention of DND. Neuroprotective effect was also found in four-vessel occlusion models after kynurenine (i.v.) administration

Iron Deposition in the Brain Following the Ischemia in a Rat Model of Ischemic Tolerance

Preconditioning of the brain by short-term ischemia increases brain tolerance to the subsequent severer ischemia. In this study, we investigated iron deposition in the cerebral cortex and the ischemic tolerance in a rat model of cerebral ischemia. Forebrain ischemia was induced by four-vessel occlusion for 5 min as ischemic preconditioning. Two days after preconditioning or after the sham-operation, the second ischemia was induced for 20 min. Changes in the cerebral cortex were examined after 1 to 8 weeks of recirculation following 20 min ischemia with or without preconditioning using the iron histochemistry. Granular deposits of the iron were found in the cytoplasm of the pyramidal cells in the layers III and V of the frontal cortex after 1 week of recirculation. When the rats were exposed to 5 min ischemia 2 days before 20 min lasting ischemia, the deposition of iron in the cytoplasm of the pyramidal cells in layers III and V of the frontal cortex was significantly lower during all periods of reperfusion. Preconditioning 5 min ischemia followed by 2 days of reperfusion before 20 min ischemia also prevented degeneration of the pyramidal neurons in layers III and V of the frontal cortex

Modelling of thermal processes at waste incineration

The article describes the possibilities of optimization of combustion processes at waste incineration, which require a specific approach in comparison with conventional fuels. The main cause is an instability of thermo-chemical properties of majority of waste. The work defines and evaluates criteria, which are critical for the waste incineration process. The numerical model “Combustion temperature” for optimization of thermal work of the waste incinerator was designed for support of implementation of other measures aimed at increasing the process energy efficiency, and it was verified in practice in real waste incineration plant.Web of Science38233533352