Number of results to display per page
Search Results
1432. Advanced purification of industrial quartz using calcination pretreatment combined with ultrasound-assisted leaching
- Creator:
- Yang, Changqiao, Han, Shuaishuai, Li, Suqin, and Bai, Jiaxing
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- geodynamika, geomechanika, geofyzika, geologie, ultrazvuk, geodynamics, geomechanics, geophysics, geology, ultrasound, křemen, quartz, high purity quartz, iron removal, calcination pretreatment, gas-liquid inclusions, ultrasound-assisted leaching, 7, and 551
- Language:
- English
- Description:
- Purification of quartz using an environment-friendly method is important in the contaminants removal. This paper presents advanced method based on calcination pretreatment combined with ultrasound-assisted leaching, for removing iron impurities from industrial quartz. The solvent used is a mixture comprised by diluted hydrochloric acid and oxalic acid. The effects of experimental parameters were investigated and the purification mechanism was discussed using particle size analyzer, scanning electron microscope and polarized light microscope. SiO2 content of concentrate could be increased from 99.6828% to 99.9047%, which achieved 3N level high purity quartz, and Fe2O3 content reduced from 0.0857% to 0.0223%, under the optimal conditions, i.e., calcination temperature of 900 °C, holding time of 2 h, oxalic acid concentration of 10 g/L, hydrochloric acid concentration of 5%, liquid solid ratio of 5, leaching temperature of 60 °C, ultrasound power of 400 W and treatment time of 30 min. Compared to conventional method, the proposed method significantly accelerates the leaching process and increases the iron removal rate. At the same time, the method also can remove gas-liquid inclusions. and Yang Changqiao, Li Suqin, Bai Jiaxing, Han Shuaishuai.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
1433. Advances in the knowledge of amphizoic amoebae infecting fish
- Creator:
- Dyková, Iva and Lom, Jiří
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- amphizoic amoebae, fish hosts, Acanthamoeba, Cochliopodium, Filamoeba, Naegleria, Neoparamoeba, Nuclearia, Platyamoeba, Thecamoeba, Vannella, and Vexillifera
- Language:
- English
- Description:
- Free-living amoebae infecting freshwater and marine fish include those described thus far as agents of fish diseases, associated with other disease conditions and isolated from organs of asymptomatic fish. This survey is based on information from the literature as well as on our own data on strains isolated from freshwater and marine fish. Evidence is provided for diverse fish-infecting amphizoic amoebae. Recent progress in the understanding of the biology of Neoparamoeba spp., agents responsible for significant direct losses in Atlantic salmon and turbot industry, is presented. Specific requirements of diagnostic procedures detecting amoebic infections in fish and taxonomic criteria available for generic and species determination of amphizoic amoebae are analysed. The limits of morphological and non-morphological approaches in species determination are exemplified by Neoparamoeba, Vannella and Platyamoeba spp., which are the most common amoebae isolated from fish gills, Acanthamoeba and Naegleria spp. isolated from various organs of freshwater fish, and by other unique fish isolates of the genera Nuclearia, Thecamoeba and Filamoeba. Advances in molecular characterisation of SSU rRNA genes and phylogenetic analyses based on their sequences are summarised. Attention is particularly given to specific diagnostic tools for fish-infecting amphizoic amoebae and ways for their further development.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1434. Adversativnite nezavisnoslozeni rečenici vo makedonskite srednovekovni rakopisi
- Creator:
- Gurkova, Aleksandra
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Macedonian studies, Old Church Slavonic, and conjunctions
- Language:
- Czech
- Description:
- The article deals with the use of different types of connectors in the adversative complex phrases in Old Church Slavonic and their Greek parallels. The most common and most frequent conjuntions are a, nž, and to a certain extent obače, whereas the particle že is mostly defined as adversative by the semantics of the clauses. In some manuscripts from the 18th and 19th centuries appart from the use of no and a, examples of adversative sentences with the conjuctions ami and tuku are frequent, which are common also in Standard Macedonian (but ami mostly in dialects). The conjuction tuku has developed from the adverb tolku and the conjunction ami is taken from the Greek vernacular ami. The use of conjunctions from other languages - ami from Greek and ama from Turkish which had a significant influence on the spoken (Slavic) language in Macedonia vis-à-vis the language used in the Old Church Slavonic manuscripts shows that it was common to accept a foreign language construction. However, it should be mentioned that both conjunctions in Standard Macedonian are used as a kind of stylistic specifity, usually in colloquial style. The development and use of new conjunctions could also be explained by the phonemic characteristic of the conjuntion nž, to lose the nasal and thus to become not expressive enough as adversative.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
1435. Adverse effects of AMP-activated protein kinase alpha2-subunit deletion and high-fat diet on heart function and ischemic tolerance in aged female mice
- Creator:
- Slámová, K., František Papoušek, Janovská, P., and Jan Kopecký
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, ischemie, infarkt myokardu, stárnutí, ischemia, myocardial infarction, aging, AMP kinase, reperfusion, high-fat diet, 14, and 612
- Language:
- English
- Description:
- AMP -activated protein kinase (AMPK) plays a role in metabolic regulation under stress conditions, and inadequate AMPK signaling may be also involved in aging process. The aim was to find out whether AMPK α 2-subunit deletion affects heart function and ische mic tolerance of adult and aged mice. AMPK α 2 -/- (KO) and wild type (WT) female mice were compared at the age of 6 and 18 months. KO mice exhibited subtle myocardial AMPK α 2-subunit protein level, but no difference in AMPK α 1-subunit was detected between the strains. Both α 1- and α 2-subunits of AMPK and their phosphorylation decreased with advanced age. Left ventricular fractional shortening was lower in KO than in WT mice of both age groups and this difference was maintained after high-fat feeding. Infarct size induced by global ischemia/reperfusion of isolated hearts was similar in both strains at 6 months of age. Aged WT but not KO mice exhibited improved ischemic tolerance compared with the younger group. High-fat feeding for 6 months during aging abolished the infarct size-reduction in WT without affecting KO animals; nevertheless, the extent of injury remained larger in KO mice. The results demonstrate that adverse effects of AMPK α 2-subunit deletion and high-fat feeding on heart function and myocardia l ischemic tolerance in aged female mice are not additive., K. Slámová, F. Papoušek, P. Janovská, J. Kopecký, F. Kolář., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
1436. Aerial photogrammetry observation of the subsidence depression near Karviná
- Creator:
- Vlastimil Kajzar, Doležalová, Hana, Kamil Souček, and Staš, Lubomír
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, letecká fotogrammetrie, aerial photogrammetry, subsidence depression, monitoring, GNSS, 7, and 551
- Language:
- English
- Description:
- Aerial photogrammetry was chosen as an additional observation method of the subsidence depression that was created above exploited coal mining panels near Karviná. While individual points of a permanent observation network were repeatedly surveyed by GNSS, the whole subsidence depression was surveyed by the aerial photogrammetry. As this method was applied three times (during three years) we can compare its results in individual years and observe the major surface changes on the undermined area. Also, a comparison was realized between the points’ coordinates gained from both aerial photogrammetry and GNSS. The results show that the method of aerial photogrammetry enriches and complements the GNSS observation in monitoring the spatial development and shape of the subsidence depression, especially in the areas of active recultivation., Vlastimil Kajzar, Hana Doležalová, Kamil Souček and Lubomír Staš., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1437. Aerobic exercise of low to moderate intensity corrects unequal changes in BKCa subunit expression in the mesenteric arteries of spontaneously hypertensive rats
- Creator:
- Zhang, Y., Chen, Y., Zhang, L., Lu, N., and Shi, L.
- Format:
- print, bez média, and svazek
- Type:
- article, články, journal articles, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, hypertenze, hypertension, exercise intensity, BKCa channel, 14, and 612
- Language:
- English
- Description:
- Accumulating evidence indicates that hypertension is associated with "ion channel remodeling" of vascular smooth muscle cells (VSMCs). The objective of this study was to determine the effects of exercise intensity/volume on hypertension-associated changes in large-conductance Ca2+-activated K+ (BKCa) channels in mesenteric arteries (MAs) from spontaneously hypertensive rats (SHR). Male SHRs were randomly assigned to three groups: a low-intensity aerobic exercise group (SHR-L: 14 m/min), a moderate-intensity aerobic exercise group (SHR-M: 20 m/min), and a sedentary group (SHR). Age-matched Wistar-Kyoto rats (WKYs) were used as normotensive controls. Exercise groups completed an 8-week exercise program. Elevation of the α and β1 proteins was unequal in MA myocytes from SHRs, with the β1 subunit increasing more than the α subunit. BKCa contribution to vascular tone regulation was higher in the myocytes and arteries of SHRs compared to WKYs. SHR BKCa channel subunit protein expression, β1/α ratio, whole cell current density and single-channel open probability was also increased compared with WKYs. Aerobic exercise lowered systemic blood pressure and normalized hypertension-associated BKCa alterations to normotensive control levels in the SHRs. These effects were more pronounced in the moderate-intensity group than in the low-intensity group. There is a dose-effect for aerobic exercise training in the range of low to moderate-intensity and accompanying volume for the correction of the pathological adaptation of BKCa channels in myocytes of MAs from SHR., Y. Zhang, Y. Chen, L. Zhang, N. Lu, L. Shi., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
1438. Aerodynamic forces measured on a fluttering profile
- Creator:
- Vlček, Václav, Zolotarev, Igor, and Kozánek, Jan
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- aeroelastic experiments, self-excited vibrations, wind tunnel, and interferometry
- Language:
- English
- Description:
- The study presents evaluation of optical measurements of the air flow field near the fluttering profile NACA0015 with two-degrees of freedom, Mach number of the flutter occurence were M = 0.21 and M = 0.45. Aerodynamic forces (drag and lift components) were evaluated independently on the upper and lower surfaces of the profile. Using the mentioned decomposition, the new information about mechanism of flutter properties was obtained. The forces on the upper and lower surfaces are phase shifted and are partially eliminated as a result of the circulation around the profile. The cycle changes of these forces cause the permanent energy contribution from the airflow to the vibrating system. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1439. Aerodynamické modelování nesymetrických revitalizačních prvků v korytech upravených malých vodních toků
- Creator:
- Havlík, Aleš
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- river restoration, diversity of flow conditions, flow capacity of channel, revitalizace, kapacita koryta, and diversifikace proudění
- Language:
- Slovak
- Description:
- Due to renaturalization of trained watercourses, the capacity of the channel is often reduced. This paper deals with influence of non-symetrical obstacles placed into channels of small trained streams upon flow characteristics. In the framework of hydraulic research on aerodynamical model, four types of obstacles of various shape were used. An evaluation of their influence on total channel resistance in dependence on depth of flow and a spacing of the obstacles is presented. and Vlivem revitalizačních zásahů do upravených vodních toků zpravidla dochází ke zmenšení kapacity koryta. Předkládaný článek se zabývá vlivem nesymetrických revitalizačních prvků, vkládaných do upravených koryt malých vodních toků, na charakter proudění. V rámci fyzikálního výzkumu na aerodynamickém modelu byly použity 4 typy prvků, které různým způsobem zasahovali do průtočného profilu. V tomto článku je zhodnocen jejich vliv na celkové odpory koryta v závislosti na hloubce proudění a vzdálenosti prvků.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1440. Aeroelastic sensitivity analysis of airliner wing
- Creator:
- Čečrdle, Jiří and Vích, Ondřej
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- aeroelasticity, flutter, eigenvalue, sensitivity, and FNG wing
- Language:
- English
- Description:
- This paper describes the airliner wing flutter sensitivity analysis. The sensitivity coefficients define the influence of the structural parameter changes to tthe structure eigenvalue and flutter stability characteristics. Evaluated structural parameters represent the possible changes of the structure due to the installation of the smart high-lift devices at the leading and trailing edge region. In general, we can suppose the increasing of the mass and mass moment of inertia around the elastic axis and decreasing of the stiffness. Described effects are ordinarily considered destabilizing regarding the flutter. The main aim of the presented work is to evaluate the impact of components to the stability and to define the most critical regions or parameters. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public