Microstructural changes initiated by sintering of refractory concrete based on recycled bauxite aggregate

Concretes whose structure and final properties are shaped during thermal pre-treatment or during life-service at elevated temperatures can be applied as construction material for thermal insulation and/or refractory linings in high-temperatureoperating plants. Refractory concretes designed with waste raw materials show satisfying performances in comparison with standard concretes. Sintering initiates microstructural changes within concrete. Concrete microstructure further develops with increasing temperature. Change progression can be monitored by means of destructive and non-destructive tests: either by investigating change of compressive strength or apparent porosity of concrete samples. Destructive tests, in this study, were applied in compressive strength investigation, while non-destructive tests were performed for results comparison. Experiment has been conducted on corundum (standard) concrete and recycled bauxite (experimental) concrete. Samples underwent thermal treatment from 110 to 1500°C. Macroperformance of the final refractory concrete was correlated to the microstructural change detected by means of XRD and SEM analysis. Creep testing was conducted to prove sintering process. Results showed that recycled concrete has equal if not better properties in comparison with standard refractory concrete and can be used as thermoinsulation or refractory material. The results presented in this paper contribute to the idea of including other testing methods (i.e. nondestructive methods) in investigation of microstructural changes and sintering process of refractory concrete. At the same time results of this investigation highlight advantages of application of secondary raw materials in design of refractory materials. Although recycled aggregate concrete showed lower compressive strength and higher porosity than commercial concrete it should be noted that both porosity and compressive strength are within satisfying value range for high-temperature application, i.e. these concretes will not be used as structural materials but as thermal insulation linings. In such application refractoriness is the property which is more important than strength. Considering the fact that compressive strength is above 50 MPa (and above 20 MPa at 1500°c) these concretes should be able to withstand load induced by other constructive parts of furnace and slag. Refractoriness test showed that bauxite-based recycled concrete is highly resistible on increasing temperatures and creep test showed initiation of sintering process. Corundum concrete can be used for temperature above 1500°c. Due to the satisfying performances it is concluded that recycled concrete can be equally used as standard concrete. Even though it has slightly lower properties, accent should be on the financial and ecological benefit found in using of recycled material and savings of energy and natural resources

Fusarium infekcija i deoksinivalenol kontaminacija ozime pšenice

In this paper, the incidence of Fusarium-infected grain of winter wheat and the content of mycotoxin deoxynivalenol (DON) was studied in two Serbian cultivars Simonida and NS40S, both harvested in 2014. The level of Fusarium contamination of wheat grain was determined using phytopathological techniques based on the standard methodology while DON was detected by enzyme-linked immuno-sorbent assay (ELISA). The incidence of Fusarium-infected grain ranged from 12 to 19% for Simonida and NS40S, respectively. Fusarium graminearum, as well-known producer of DON mycotoxin, was identified among Fusarium species. In addition, Alternaria spp. was isolated in high percentage, with an average incidence of 53% (Simonida) to 63% (NS40S).The average content of DON ranged from 424 μg kg-1 to 1101 μg kg-1 for Simonida and NS40S cultivars, respectively. Statistically insignificant negative correlation (r = - 0.18) was determined between Fusariuminfected grain and DON in the cultivar Simonida and statistically insignificant positive correlation (r = 0.11) in the cultivar NS40S. The mean levels of DON in studied wheat samples of both tested cultivars were not higher than the maximum permitted limit (1250 μg kg-1) although the level of Fusarium-infected grain of both cultivars was relatively high. These results indicate that both wheat cultivars are susceptible to Fusarium infection and DON mycotoxin production in agro-ecological conditions of Serbia, but the cultivar NS40S being more susceptible compared to cultivar Simonida. In view of all stated above, regular health check of grains and developing strategies for integrated monitoring of incidence of Fusarium head blight are necessary preventive measures in protection of winter wheat.U radu je proučavana incidenca Fusarium-zaraženih zrna ozime pšenice iz žetve 2014. godine kod dve domaće komercijalne sorte Simonida i NS40S, kao i sadržaj mikotoksina deoksinivalenola (DON). Nivo fuzariozne kontaminacije zrna pšenice određen je primenom fitopatoloških testova standardne metodologije a DON je detektovan primenom imunoadsorpcione enzimske metode (ELISA). Incidenca Fusarium-zaraženih zrna bila je u proseku za sve ispitivane uzorke od 12% (Simonida) do 19% (NS40S). Od Fusarium vrsta identifikovana je jedino Fusarium graminearum, kao dobro poznati producent DON mikotoksina. Pored ove gljivične vrste, u visokom procentu izolovana je Alternaria spp. sa prosečnom incidencom od 53% (Simonida) do 63% (NS40S). U ispitivanim uzorcima pšenice prosečan sadržaj DON bio je od 424 μg kg-1 (Simonida) do 1101 μg kg-1 (NS40S). Između Fusarium-zaraženih zrna i DON utvrđena je statistički neznačajna negativna korelacija (r = - 0.18) kod sorte Simonida i statistički neznačajna pozitivna korelacija (r = 0.11) kod sorte NS40S. Prosečne koncentracije DON u ispitivanim uzorcima pšenice kod obe ispitivane sorte nisu bile iznad maksimalno dozvoljenog limita iako je nivo fuzariozne kontaminacije zrna obe ispitivane sorte bio visok. Ovi rezultati ukazuju da su obe ispitivane sorte pšenice osetljive prema fuzarioznoj infekciji i produkciji DON mikotoksina u agroekološkim uslovima Srbije, s tim što je sorta NS40S osetljivija u odnosu na sortu Simonida. Zbog svega navedenog, redovna zdravstvena kontrola zrna i razvijanje strategije integralnog monitoringa fuzarioze klasa neophodne su preventivne mere borbe u zaštiti pšenice

Glutathione status in the blood of rats after reticulocytosis induced by phenylhydrazine and bleeding

In this experiment, we compared the in vivo effects of phenylhydrazine (PHZ) and bleeding treatment on the redox status and glutathione antioxidative mechanism parameters in the plasma and red blood cells (RBC) of rats. Results showed a lower level of reactive oxygen species (ROS), a higher level of lipid peroxidation and the effective antioxidative role of the glutathione system in the blood of bleeding rats. PHZ-treatment induced higher concentrations of ROS and an accumulation of oxidized glutathione in the plasma, while the glutathione system showed a satisfactory antioxidative capacity in the RBC of rats. When comparing the two anemic groups, the PHZ-treated rats showed marked oxidative stress in the plasma

Cesium removal from aqueous solution by natural mineral clinoptilolite

The aim of this study was to investigate the Cs+ ions sorption on natural minerals clinoptilolite. The analysis of clinoptilolite and clinoptilolite with adsorbed Cs+ ion was conducted by X-ray diffraction, scanning electron microscopy, X-ray fluorescence, and gamma spectrometry. The specific activity of naturally occurring radionuclides in clinoptilolite was determined by gamma spectrometry by using the HPGe semiconductor detector. Obtained activity concentrations ranged from 49 Bq/kg to 810 Bq/kg for K-40, 5.7 Bq/kg to 10 Bq/kg for U-238, 5.8 Bq/kg to 70 Bq/kg for Th-232(Ac-228), and the presence of artificial radionuclides was not detected (Cs-137 lt 0.02 Bq/kg). The study of the thermal decomposition of raw clinoptilolite and Cs adsorbed clinoptilolite by differential thermal analysis is presented in this paper. The activation energy of the reaction phase transformation of raw clinoptilolite is 156.7 kJ/mol, while Cs adsorbed clinoptilolite is 121.7 kJ/mol. The lower value of activation energy reaction of the phase transformation Cs adsorbed clinoptilolite indicates that Cs which is adsorbed destabilizes the crystal structure of clinoptilolite and thus facilitates the transition to the amorphous state

Synthesis and sintering of high-temperature composites based on mechanically activated fly ash

Amount of fly ash which is and yet to be generated in the coming years highlights the necessity of developing new methods of the recycling where this waste can be reused in significant quantity. A new possibility for fly ash utilization is in high-temperature application (thermal insulators or/and refractory material products). As such, fly ash has to adequately answer the mechanical and thermal stability criteria. One of the ways of achieving it is by applying mechanical activation procedure on fly ash. In present study, fly ashes from two different power plants were mechanically activated in a planetary ball mill. Mechanically treated fly ashes were cemented with two different binders: standard Portland cement and high-aluminates cement. Physico-chemical analysis and investigation of mineralogical components of composites are emphasized, due to the changes occurred in fly ash during mechanical activation and sintering of composites. Macro-performance of the composites was correlated to the microstructure of fly ash studied by means of XRD and SEM analysis. Thermal stability of crystalline phases was investigated with DTA. Highlight was placed on determination of relationship between mechanically activated fly ash and obtained composites microstructure on one side and behavior of sintered composites on the other side. [Projekat Ministarstva nauke Republike Srbije, br. 172057, 45008 and a project F-198, financed by Serbian Academy of Sciences and Arts

Presence of deoxynivalenol in winter wheat treated with fungicides

Natural occurrence of Fusarium spp. and concentrations of mycotoxin deoxynivalenol (DON) in the grain of the winter wheat moderately susceptible to Fusarium head blight (FHB) has been studied. Grain samples were collected from wheat crops intended mainly for human consumption. All wheat crops were treated with fungicides before (a.i. flutriafol - formulated as Fluoco, applied in dose of 0.5 l ha-1) and during the flowering phase of growing (a.i. thiophanate-methyl + epoxiconazole formulated as Eskorta plus and a.i. thiophanate-methyl formulated as Funomil, applied in doses of 0.75 and 0.5 l ha-1, respectivily). Among of Fusarium species only F. graminearum, as a well known producer of DON, was identified. This fungus was identified in 15 of 19 samples (78.9%) with incidence in positive samples of 2 to 28% (average, 14.0%). Presence of DON was established in 13 of a total 19 investigated wheat grain samples (68.4%). In positive samples DON was detected in concentrations from 69 to 918 μg kg-1 (average, 478 μg kg-1). DON showed a significant and positive correlation at P≥0.05 with grain moisture content (r = 0.52*). Between the frequency of F. graminearum and concentration of DON and between the frequency of F. graminearum and grain moisture content, positive correlation was determined, but without statistical significance (r = 0.44 and r = 0.29, respectively)

Late Phase Cell-Cycle Proteins in Postmitotic Neurons: Relation to Alzheimer’s Disease?

Cell cycle re-entry has become a well established model of neuropathogenesis in Alzheimer’s disease (AD). We and others have demonstrated expression of early phase cell cycle-related proteins in the vulnerable neurons in AD. Evidence that this represents a bona fide mitotic event is verified by the observation that DNA replication does in fact occur in these cells. Notably, the relatively early occurrence of cell cycle events in AD suggests that a mitotic cell cycle related mechanism may play a pivotal role in the disease. Still, a number of features of the cell cycle re-entry phenotype have remained elusive to the role of ectopic protein expression in the process of neuronal cell death. Late phase cell cycle proteins regulate separation and segregation of chromosomes. The centromere region is crucial to this process. Until recently there has been no data on the role of proteins controlling the centromere region in postmitotic neurons. This new data suggests that cohesin complexes that mediate sister–chromatid cohesion in dividing cells may also contribute to gene regulation in postmitotic cells. Therefore, centromere-cohesin proteins may play a secondary role in the cell, i.e. one that is independent of their role in cohesion and chromosome segregation. Evidence demonstrating that instability of centromere-cohesion dynamics in the early phases of the cell cycle which coincide with re-entry alteration of cortical neurons enables the possibility to further elucidate initial processes leading to AD

Periodontal medicine: The emergence of a new branch in periodontology

Introduction: Periodontal medicine is the emergence of a new branch of periodontology. Periodontal medicine is a term used for different purposes in different parts of the world. In certain countries, it relates to the study of the dynamic relationship between periodontal diseases and systemic conditions, such as cardiovascular and cerebrovascular disease, preterm delivery low-birth-weight babies, diabetes mellitus, osteoporosis, and disorders of the respiratory tract. Such studies investigate the peripheral impacts of periodontal inflammation on systemic health. In other countries, 'periodontal medicine' is a term used to describe the periodontal (and gingival) manifestations of medical conditions. This includes their investigation, diagnosis and therapeutic management and how management of the oral condition integrates with the patient's medical management as part of a holistic approach within defined care pathways. Conclusion: The text is a comprehensive analysis of research on periodontal disease and its link to systemic conditions. The periodontal treatment may be important in terms of preventing a patient's overall health. Periodontologists emphasize that infections in the mouth can cause health problems in other parts of the body

Lipid Peroxidative Damage on Cisplatin Exposure and Alterations in Antioxidant Defense System in Rat Kidneys: A Possible Protective Effect of Selenium

Cisplatin (Cis-diamminedichloroplatinum II, CP) is an important chemotherapeutic agent, useful in the treatment of several cancers, but with several side effects such as nephrotoxicity. The present study investigated the possible protective effect of selenium (Se) against CP-induced oxidative stress in the rat kidneys. Male Wistar albino rats were injected with a single dose of cisplatin (7 mg CP/kg b.m., i.p.) and selenium (6 mg Se/kg b.m, as Na2SeO3, i.p.), alone or in combination. The obtained results showed that CP increased lipid peroxidation (LPO) and decreased reduced glutathione (GSH) concentrations, suggesting the CP-induced oxidative stress, while Se treatment reversed this change to control values. Acute intoxication of rats with CP was followed by statistically significant decreased activity of antioxidant defense enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR) and glutathione-S-transferase (GST). Treatment with Se reversed CP-induced alterations of antioxidant defense enzyme activities and significantly prevented the CP-induced kidney damage

A Next-Generation Liquid Xenon Observatory for Dark Matter and Neutrino Physics

The nature of dark matter and properties of neutrinos are among the mostpressing issues in contemporary particle physics. The dual-phase xenontime-projection chamber is the leading technology to cover the availableparameter space for Weakly Interacting Massive Particles (WIMPs), whilefeaturing extensive sensitivity to many alternative dark matter candidates.These detectors can also study neutrinos through neutrinoless double-beta decayand through a variety of astrophysical sources. A next-generation xenon-baseddetector will therefore be a true multi-purpose observatory to significantlyadvance particle physics, nuclear physics, astrophysics, solar physics, andcosmology. This review article presents the science cases for such a detector.<br