104 research outputs found
Communicatives in the differently structured languages
The problem of the culturally conditioned use of Russian interrogative communicatives (colloq), is solved in the article on the background of the equivalent English disjunctive question (in which the verbal-subjective inversion and different polarity are used, for example, didnt she, haven't they, doesn't it ) and the Japanese particle ne. In English such communicatives include the second part of the disjunctive question (didn't she?, isn't she?), synonymous with the Japanese particle ne? and Russian particles? In the Russian language there are two groups of communicatives that can be translated into English by a disjunctive question: 1) particles that call for agreement and synonymous with them; 2) particles that are not synonymous with communicatives, calling for agreement. Sentences with Russian particles and synonymous with them, as well as particlesare translated into English by a disjunctive question with a greater or lesser degree of frequency. Sentences with such particles as are translated mainly by a disjunctive question. For sentences with particles the translation by a general or special question is more typical, although such sentences can as well have the disjunctive question as an English equivalent, that indicates the importance for Anglo-American thinking to emphasize the right of every person to express his opinion openly (agreement or disagreement with the point of view of the addressee)
Effect of the Addition of Thermally Activated Heavy Loam to Portland Cement on the Properties of Cement Stone
© 2018, Pleiades Publishing, Ltd. In the past decades, metakaolin additives synthesized by the calcination of kaolin clays have been implemented in cement systems. Their scarcity and high cost promotes the studies on the effectiveness of thermally activated additives of common polymineral clays. This article presents the results of research on the effect of thermally activated heavy loam additives to Portland cement. It was shown that additives of 5–15% heavy loam calcined at certain temperatures in the range of 400—600°C and ground to a certain specific surface area of up to 250–500 m2/kg lead to a more significant increase in the strength, density, and water resistance of cement stone than corresponding metakaolin additives with the specific surface area of 1200 m2/kg
Properties of Portland cement paste incorporated with loamy clay
© 2017 The Korean Society of Mineral and Energy Resources Engineers (KSMER)Metakaolin which is calcined kaolin clay is being widely applied as supplementary cementitious materials for Portland cement. Due to their scarcity and high cost, calcined ubiquitous polymineral clays are actively studied as alternative to metakaolin. This article presents the study results of influence of calcined ground loamy clay on the properties of Portland cement paste. About 5–15% of loamy clay calcined at 400–600 °C and ground to 250–500 m2/kg were found to be more effective compared to metakaolin of specific surface area of 1200 m2/kg for improvement of compressive strength, water resistance, and increase in density of hardened Portland cement paste
Influence of the calcined light loam on the properties of the hardened portland cement paste
© 2017, Fundatia Serban Solacolu. All rights reserved. The increasing worldwide production of Portland cement and demand to reduce CO 2 emissions has resulted in the need to increase the volume and varieties of supplementary cementitious materials. The most promising source of raw materials for the production of supplementary cementitious materials is ubiquitous and unlimited reserves of polymineral clays. In this article the effect of calcined loam clays depending on its concentration, calcination temperature (400-800°C), and specific surface area (250-800 m 2 /kg) on the properties of Portland cement is studied. It is found out the calcined loam clays increase the compressive strength of Portland cement hardened paste up to 35%, density up to 1.4%, water resistance from 0.92 to 0.93-0.97, and decrease the water adsorption from 1 to 0.9%. The reasonability of production and application of calcined loam clays, which aren’t lower in efficiency than high-priced metakaolin, is stated
Influence of limestone content, fineness, and composition on the properties and microstructure of alkali-activated slag cement
© 2016 Elsevier LtdThe influence of the fineness, concentration, and chemico-mineralogical composition of limestone on the workability, reaction kinetics, compressive strength, microstructure, and binder gel characteristics of sodium carbonate–based waste-activated waste slag cement pastes was investigated in this work. Alkali-activated slag cements incorporated with limestone, containing 33–100% of calcite, at a content of up to 60% with a 28-day compressive strength of 26.2–48.8 MPa were proposed. The main reaction products of hardened alkali-activated cement pastes and those incorporated with limestone are [Formula presented], CaCO3, Na2Ca(CO3)2·5H2O, and Na2CaSiO4. “Physically active” limestone does not chemically react with the binder gel but it can improve the physical structure. The higher packing density of mixed cement, without an increase in the water demand, the satisfactory binding strength of limestone with the binder gel lead to the improvement in the physical structure and compressive strength of alkali-activated slag paste
Study of biochemical markers in newborns with necrotizing enterocolitis
Aim. To study the level of biochemical markers to optimize the diagnosis and prognosis of necrotizing enterocolitis in newborns.
Methods. 110 newborns with necrotizing enterocolitis were observed in the intensive care unit at the age of 1 to 28 days. According to the stages of necrotizing enterocolitis, all examined newborns were divided into three groups. Group 1 consisted of 49 newborns (40.5%) with necrotizing enterocolitis stage I, group 2 included 48 newborns (39.7%) with necrotizing enterocolitis stage II and group 3 included 13 newborns (10.7%) with necrotizing enterocolitis stage III. In 40 newborns with necrotizing enterocolitis, matrix metalloproteinase-2, -9, -17, cathelicidin, transferrin in the blood and fecal calprotectin in the feces were measured by ELISA.
Results. Comparative analysis demonstrated that matrix metalloproteinase-2 was increased in newborns from group 1 by 6.9 times, in group 2 - by 8.3 times and in group 3 - by 10.7 times. Similarly, the level of metalloproteinase-9 was increased in group 1 by 3 times, in group 2 by 3.4 times, and in group 3 by 4.5 times compared to the newborns from the control group. The concentration of metalloproteinase-17 in newborns from groups 1 and 2 was almost the same and increased on average by 2.5 times, and by 3.6 times in group 3 compared to the control. In examined newborns, the highest level of cathelicidin and lowest level of transferrin were observed in necrotizing enterocolitis stage III, which indicates the more severe course of the disease and may be a predictor of changes in treatment tactics. So, taking into account the diagnostic value of fecal calprotectin (75%), it can be used as a noninvasive marker of inflammation in the intestine.
Conclusion. The established changes in the level of biochemical markers (metalloproteinases, cathelicidin and transferrin in the blood and fecal calprotectin in feces) have diagnostic and prognostic value in the diagnosis, prediction of outcomes and optimization of treatment tactics of necrotizing enterocolitis in neonatal practice
Solidification of nitrate solutions with alkali-activated slag and slag-metakaolin cements
© 2014 Elsevier B.V. All rights reserved. The solidification of nitrate solutions with alkali-activated slag (AASC) and slag-metakaolin cements (AASMC) and the resulting setting times, compressive strengths, dimensional stability, water resistance, hydration products, microstructures, and macroporous network structures were evaluated. The influences of the alkali activator concentration, mineral composition of metakaolin, ratio of slag to slag + metakaolin, and concentration of NaNO3 on the cement performance were all evaluated in detail. The compressive strength of cemented nitrate solutions with AASC and AASMC aged for 28 days was from 13.4 to 42 MPa depending on the NaNO3 concentration. X-ray diffractometer, differential thermal analyzer, and electron microscope analyses suggested that NaNO3 crystallizes in cementitious matrices without reacting with the hydration products of AASC and AASMC. X-ray microtomography showed that the solidified NaNO3 solution with a salt concentration of 700 g/l and AASC had a denser microstructure without shrinkage microcracks, a smaller macropore volume, and smaller macropore sizes than hardened AASC-based paste mixed with water
Marl-based geopolymers incorporated with limestone: A feasibility study
© 2018 Elsevier B.V. The expanding raw materials base is one of the drivers for the further development of inorganic binders, including alkali-activated cements. This research focuses on studying marl with a high calcite/aluminosilicates ratio as a geopolymer precursor, and limestone as a mineral addition to this geopolymer. The calcination of marl at 800 °C resulting in the formation of reactive Si, Al, and Ca due to the dehydroxylation of clay minerals and decarbonation of calcite makes marl suitable for use as a geopolymer precursor. Calcined marl activated with sodium silicate and cured at ambient temperature had a 28-day compressive strength of 34 MPa. When incorporated with 50% limestone, the compressive strength became 39.2 MPa. XRD, TG/DSC, FTIR, optical and SEM have been used to investigate the reaction products, as well as the microstructure of the geopolymer hardened pastes
Caenorhabditis elegans Semi-Automated Liquid Screen Reveals a Specialized Role for the Chemotaxis Gene cheB2 in Pseudomonas aeruginosa Virulence
Pseudomonas aeruginosa is an opportunistic human pathogen that causes infections in a variety of animal and plant hosts. Caenorhabditis elegans is a simple model with which one can identify bacterial virulence genes. Previous studies with C. elegans have shown that depending on the growth medium, P. aeruginosa provokes different pathologies: slow or fast killing, lethal paralysis and red death. In this study, we developed a high-throughput semi-automated liquid-based assay such that an entire genome can readily be scanned for virulence genes in a short time period. We screened a 2,200-member STM mutant library generated in a cystic fibrosis airway P. aeruginosa isolate, TBCF10839. Twelve mutants were isolated each showing at least 70% attenuation in C. elegans killing. The selected mutants had insertions in regulatory genes, such as a histidine kinase sensor of two-component systems and a member of the AraC family, or in genes involved in adherence or chemotaxis. One mutant had an insertion in a cheB gene homologue, encoding a methylesterase involved in chemotaxis (CheB2). The cheB2 mutant was tested in a murine lung infection model and found to have a highly attenuated virulence. The cheB2 gene is part of the chemotactic gene cluster II, which was shown to be required for an optimal mobility in vitro. In P. aeruginosa, the main player in chemotaxis and mobility is the chemotactic gene cluster I, including cheB1. We show that, in contrast to the cheB2 mutant, a cheB1 mutant is not attenuated for virulence in C. elegans whereas in vitro motility and chemotaxis are severely impaired. We conclude that the virulence defect of the cheB2 mutant is not linked with a global motility defect but that instead the cheB2 gene is involved in a specific chemotactic response, which takes place during infection and is required for P. aeruginosa pathogenicity
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