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Wyszukujesz frazę "Pérez, S." wg kryterium: Autor


Tytuł:
Successive Methods for the Separation of Titanium Oxide from the Black Sands of Ecuador
Autorzy:
Perez, S. M.
Sharadqah, S.
Powiązania:
https://bibliotekanauki.pl/articles/123820.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
ion-exchange resin
muisne
Eesmeraldas
Ecuador
black sands
titanium dioxide
Opis:
The black sands found on certain Ecuadorian beaches present a high ilmenite contents up to 50%. In this work, TiO2 was obtained from the black sands of Muisne beaches – Ecuador by combining the thermal, chemical and ion exchange treatments. For the thermal treatment, the raw material was smelted at temperature of 1100 °C using a basic flux. Subsequently, the chemical treatment was initiated in the presence of Fe0 metal using chemical digestion with HCl, and the sample was purified by separating the precipitates from a series of reactions developed at different pHs with NH4OH, Na2S and HCl. The final effluent resulting from the last HCl digestion was purified by ion exchange using Amberlite IRA 400 resin of strongly anionic character. The effluent is then treated in basic medium and the resulting precipitate is calcined. The recovery yield of the TiO2 pigment was 46% with 92% purity.
Źródło:
Journal of Ecological Engineering; 2018, 19, 1; 186-190
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Submillimeter-Wave Oscillations in Recessed InGaAs/InAlAs Heterostructures: Origin and Tunability
Autorzy:
Pérez, S.
Mateos, J.
González, T.
Powiązania:
https://bibliotekanauki.pl/articles/1505462.pdf
Data publikacji:
2011-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
85.30.Fg
07.57.Hm
73.40.Kp
Opis:
By means of an ensemble Monte Carlo simulator, the appeareance of THz oscillations in InAlAs/InGaAs slot diodes is predicted when the applied bias exceeds the threshold for intervalley transfer. Such high frequency is attained by the presence of a Gunn-like effect in the recess-to-drain region of the device channel whose dynamics is controlled by ballistic Γp valley electrons. In this work we explain the mechanism at the origin of this effect and also the influence of the bias conditions, δ-doping, recess-to-drain distance and recess length on the frequency of the ultrafast Gunn-like oscillations. The simulations show that a minimum value for the δ-doping is necessary to have enough carrier concentration under the recess and allow the oscillations to emerge. Finally, we show that shortening the devices (small recess and recess-to-drain lengths) increases the oscillation frequency, so provides an interesting frequency tunability of this THz source.
Źródło:
Acta Physica Polonica A; 2011, 119, 2; 111-113
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Iceberg Melting and Climate Change in NW Atlantic Waters
Autorzy:
Perez-Gruszkiewicz, S.E.
Peterson, W.
Powiązania:
https://bibliotekanauki.pl/articles/117122.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
Arctic shipping
climate change
Iceberg
Atlantic Ocean
NW Atlantic
iceberg melting
Labrador
International Ice Patrol (IIP)
Opis:
Climate change is predicted to cause increases in sea surface temperature (SST), as well as decreases in sea-ice cover, wind and current velocities. These changes will have a marked effect on iceberg melting in the shipping lanes off Newfoundland and Labrador, Canada. Icebergs that today can cross from northern Labrador to Newfoundland without melting will in the future have to be much larger to survive the transit. For example, icebergs at N Labrador in December of 2016 that are smaller than 156 m will melt before reaching 48N, but in year 2100 the length increases to 228 m. In addition, if future iceberg size distributions off Labrador are the same as today, icebergs will experience roughly 50% reductions in numbers in the NW Atlantic shipping lanes by year 2100. The increased melting rates are due to, in order of importance, increased sea-surface temperatures (responsible for 66% of the increase in the minimum transit size), decreasing current velocities (31%), and decreasing sea-ice cover (3%). Decreasing sea-ice tends to increase wave heights as well as accelerate the effects of wave erosion; however, for the areas studied the wave height is predicted to decrease moderately in year 2100, by a maximum of about 10% in December.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2018, 12, 3; 459-467
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical Investigation of Large-Signal Noise in Nanometric Schottky-Barrier Diodes Operating in External Resonant Circuits
Autorzy:
Shiktorov, P.
Starikov, E.
Gružinskis, V.
Varani, L.
Vaissière, J.
Reggiani, L.
Pérez, S.
González, T.
Powiązania:
https://bibliotekanauki.pl/articles/1178800.pdf
Data publikacji:
2005-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Ht
72.30.+q
72.70.+m
Opis:
We report Monte Carlo simulations of electronic noise in heavily doped nanometric GaAs Schottky-barrier diodes operating in series with a parallel resonant circuit when a high-frequency large-signal voltage is applied to the whole system. Significant modifications of the noise spectrum with respect to the unloaded diode are found to occur in the THz-region.
Źródło:
Acta Physica Polonica A; 2005, 107, 2; 396-399
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of polyvinylpyrrolidone adsorption on stability of silica aqueous suspension - effects of polymer concentration and solid content
Autorzy:
Perez Huertas, S.
Terpiłowski, K.
Wiśniewska, M.
Zarko, V.
Powiązania:
https://bibliotekanauki.pl/articles/110357.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
silica suspension stability
polyvinylpyrollidone adsorption
solid content
steric stabilization
zeta potential
Opis:
The influence of polyvinylpyrrolidone (PVP) adsorption on the silica suspension stability was studied. The effects of silica content, polymer addition and suspension dilution with water were examined. The turbidimetry method was applied to examine stability of the investigated systems as a function of time. It was shown that the suspension without polymer was characterized by the smallest stability, whereas the systems containing PVP (before and after dilution) are successively stable. The specific conformation of PVP chains on the solid surface is responsible for the stabilization–flocculation properties of PVP in the colloidal suspension.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 1; 121-135
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Co-occurrence of pathogenic and non-pathogenic Fusarium decemcellulare and Lasiodiplodia theobromae isolates in cushion galls disease of cacao (Theobroma cacao L.)
Autorzy:
Castillo,del, D.S.
Parra, D.
Noceda, C.
Perez-Martinez, S.
Powiązania:
https://bibliotekanauki.pl/articles/66527.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
co-occurrence
pathogenic fungi
non-pathogenic microorganism
Fusarium decemcellulare
Lasiodiplodia theobromae
isolate
fungi
gall disease
cacao
Theobroma cacao
Opis:
Flowery cushion gall of cacao is a disease complex with six types. Fusarium decemcellulare have been isolated from both flowery and green point galls and recognized as the etiological agent of the disease. In the present work we: i) identified by ITS-rDNA sequencing and/or taxonomy the cultivable fungal species or Operative Taxonomic Units (OTUs) associated with the five symptoms of cushion galls in cacao from Venezuela, and ii) determined the gall inducing capacity on cacao peeled seeds after 45 days of inoculation with suspensions of mycelia/ spores from distinct isolate types. The whole isolate collection rendered an abundance of 113 isolates with a richness of 39 OTUs (27) and eight identified at the species or genera levels, respectively, and in unidentified fungi. The dominant recovered species (≈36%) were F. decemcellulare and Lasiodiplodia theobromae. Some isolates of F. decemcellulare, L. theobromae, F. equiseti, Fusarium spp., F. solani, F. incarnatum, Rhizocthonia solani and Penicillium sp. were pathogenic. Some other isolates of the first six mentioned taxa behave as non-pathogenic. Furthermore, pathogenic and non-pathogenic isolates can also co-occur within a single plant and gall type. Moreover, 2–5 species within a single gall symptom in a single tree were identified (not necessarily at the same point in the tree), indicating a broad diversity of co-occurring taxa.
Źródło:
Journal of Plant Protection Research; 2016, 56, 2
1427-4345
Pojawia się w:
Journal of Plant Protection Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Branching system of the Mexican hawthorn “Tejocote” (Crataegus spp.)
Autorzy:
Perez-Ortega, S.A.
Mendez-Santiago, A.H.
Nieto-Angel, R.
Jankiewicz, L.S.
Powiązania:
https://bibliotekanauki.pl/articles/2039.pdf
Data publikacji:
2013
Wydawca:
Instytut Ogrodnictwa
Tematy:
edible hawthorn
Mexican hawthorn
fruit tree
Crataegus
canopy architecture
branching system
inflorescence
morphological diversity
Źródło:
Journal of Horticultural Research; 2013, 21, 1
2300-5009
Pojawia się w:
Journal of Horticultural Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quantization of electromagnetic modes in a hyperbolic negative-index layered superconductor slab
Autorzy:
Cortés-López, S.
Pérez-Rodríguez, F.
Powiązania:
https://bibliotekanauki.pl/articles/1062050.pdf
Data publikacji:
2016-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Gz
74.25.N-
74.78.Fk
78.67.Pt
Opis:
We theoretically study the infrared reflectivity and transmissivity of a high-temperature layered superconductor slab. Both infrared spectra exhibit very narrow Fabry-Perot resonances associated with the quantization of the wave vector of the TM electromagnetic modes. The resonances are observed in a pass band where the refractive index of the layered superconductor is negative. The pass band of negative dispersion is above the Josephson plasma frequency which appears in the expression for the effective permittivity component, corresponding to the direction perpendicular to the layers. It was found that the Fabry-Perot resonances undergo a blue shift as the slab thickness or the angle of incidence are increased. Moreover, the quantized electromagnetic modes turn out to be quasi-longitudinal because of the strong anisotropy of the infrared dielectric response of the layered superconductor.
Źródło:
Acta Physica Polonica A; 2016, 130, 2; 641-644
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative study of airborne Alternaria conidia levels in two cities in Castilla-La Mancha (central Spain), and correlations with weather-related variables
Autorzy:
Sabariego, S.
Bouso, V.
Perez-Badia, Rosa
Powiązania:
https://bibliotekanauki.pl/articles/49997.pdf
Data publikacji:
2012
Wydawca:
Instytut Medycyny Wsi
Opis:
Alternaria conidia are among the airborne biological particles known to trigger allergic respiratory diseases. The presented paper reports on a study of seasonal variations in airborne Alternaria conidia concentrations in 2 cities in the central Spanish region of Castilla-La Mancha, Albacete and Toledo. The influence of weather-related variables on airborne conidia levels and distribution was also analysed. Sampling was carried out from 2008-2010 using a Hirst sampler, following the methodology established by the Spanish Aerobiology Network. Annual airborne Alternaria conidia counts were higher in Toledo (annual mean 3,936 conidia) than in Albacete (annual mean 2,268 conidia). Conidia were detected in the air throughout the year, but levels peaked between May-September. Considerable year-on-year variations were recorded both in total annual counts and in seasonal distribution. A significant positive correlation was generally found between mean daily Alternaria counts and both temperature and hours of sunlight, while a significant negative correlation was recorded for relative humidity, daily and cumulative rainfall, and wind speed. Regression models indicated that between 31%-52% of the variation in airborne Alternaria conidia concentrations could be explained by weather-related variables.
Źródło:
Annals of Agricultural and Environmental Medicine; 2012, 19, 2
1232-1966
Pojawia się w:
Annals of Agricultural and Environmental Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A comparison of hole-filling methods in 3D
Autorzy:
Pérez, E.
Salamanca, S.
Merchán, P.
Adán, A.
Powiązania:
https://bibliotekanauki.pl/articles/331035.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
3D polygonal model
repairing meshes
hole filling
restoration algorithm
model wielokątny 3D
renowacja siatki
algorytm renowacji
Opis:
This paper presents a review of the most relevant current techniques that deal with hole-filling in 3D models. Contrary to earlier reports, which approach mesh repairing in a sparse and global manner, the objective of this review is twofold. First, a specific and comprehensive review of hole-filling techniques (as a relevant part in the field of mesh repairing) is carried out. We present a brief summary of each technique with attention paid to its algorithmic essence, main contributions and limitations. Second, a solid comparison between 34 methods is established. To do this, we define 19 possible meaningful features and properties that can be found in a generic hole-filling process. Then, we use these features to assess the virtues and deficiencies of the method and to build comparative tables. The purpose of this review is to make a comparative hole-filling state-of-the-art available to researchers, showing pros and cons in a common framework.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2016, 26, 4; 885-903
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heating source localization in a reduced time
Autorzy:
Beddiaf, S.
Autrique, L.
Perez, L.
Jolly, J. C.
Powiązania:
https://bibliotekanauki.pl/articles/331120.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
parameter identification
inverse heat conduction problem
optimal observation
source localization
identyfikacja parametryczna
odwrotne zagadnienie termiczne
obserwacja optymalna
lokalizacja źródła
Opis:
Inverse three-dimensional heat conduction problems devoted to heating source localization are ill posed. Identification can be performed using an iterative regularization method based on the conjugate gradient algorithm. Such a method is usually implemented off-line, taking into account observations (temperature measurements, for example). However, in a practical context, if the source has to be located as fast as possible (e.g., for diagnosis), the observation horizon has to be reduced. To this end, several configurations are detailed and effects of noisy observations are investigated.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2016, 26, 3; 623-640
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stirling numbers with negative indices
Autorzy:
Yaljá Montiel-Pérez, J.
López-Bonilla, J.
Vidal-Beltrán, S.
Powiązania:
https://bibliotekanauki.pl/articles/1177734.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Gould and Schläfli formulas
Stirling numbers
Opis:
We realize applications of expressions for Stirling numbers with negative indices, in particular, we show that the formulas of Zhi-Hong Sun are consequences of the known identities of Schläfli and Gould.
Źródło:
World Scientific News; 2018, 101; 217-221
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Influence of Magnetic History on the Stability of Critical State and the Dynamics of Flux Jumps in Conventional NbTi Superconductor
Autorzy:
Nabiałek, A.
Vasiliev, S.
Chabanenko, V.
Perez-Rodriguez, F.
Piechota, S.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/1537035.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.Ad
74.25.Sv
Opis:
We studied the influence of magnetic history on the stability of critical state and the dynamics of flux jumps in conventional NbTi superconductor. We have found that both the stability of critical state and the dynamics of flux jumps are strongly influenced by the magnetic history and by the magnetic field distribution induced within the sample by preceding jumps. This magnetic field distribution can be particularly complex in the region of the hysteresis loop where the external magnetic field changes its sign (region of remagnetization), because of demagnetizing effects. For this reason, the most complex structure of the flux jumps is observed in the third quadrant of magnetization hysteresis loop. Flux jumps observed in the region of remagnetization have different dynamics in comparison to the jumps observed in other regions of the magnetization hysteresis loop. Duration of these jumps is usually significantly longer than others, and their structure is more complex.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 343-345
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An association between organophosphate pesticides exposure and Parkinsonism amongst people in an agricultural area in Ubon Ratchathani Province, Thailand
Autorzy:
Norkaew, S.
Lertmaharit, S.
Wilaiwan, W.
Siriwong, W.
Perez, H.M.
Robson, M.G.
Powiązania:
https://bibliotekanauki.pl/articles/873417.pdf
Data publikacji:
2015
Wydawca:
Narodowy Instytut Zdrowia Publicznego. Państwowy Zakład Higieny
Tematy:
organophosphate pesticide
human exposure
human disease
cholinesterase activity
Parkinson's disease
agricultural area
Ubon Ratchathani province
Thailand
Opis:
Background. Parkinson’s disease (PD) is a ubiquitous disease. However, PDs prevalence in the population of agricultural communities lacks understanding and there has been no epidemiological study on the association between pesticides exposure factors and risk for PD. Objective. To investigate the potential association between organophosphate pesticides exposure and Parkinsonism by using a screening questionnaire in agricultural areas. Material and Methods. Ninety elderly people living in agricultural areas participated in a cross-sectional study conducted at Tambon Hua-Rua Health Promoting Hospital in April 2014. Screening questionnaires for Parkinson’s disease, Test-mate ChE (Model 400) for blood cholinesterase (ChE) levels of both blood enzymes erythrocyte cholinesterase (AChE), and plasma cholinesterase (PChE) were used as measurement tools. Descriptive statistics for frequencies and percentage distributions were used primarily to summarize and describe the data. Sensitivity, specificity, positive and negative predictive values were calculated. Results. The age range of the participants was 50 to 59 years old, with an average age of 53.9+2.87 years. The majority of the participants were female (62.2%), 82.2% of respondents were farmers. Most of participants (76.7%) reported that they applied insecticides in their farms. Ninety persons participated and completed the 11-item questionnaire. Of these, 17 (18.9%) felt that they lost balance when turning or that they needed to take a few steps to turn right around and 16.7% of participants indicated that they felt the need to move slowly or stiffly. The study found the prevalence of abnormal AChE levels was 28.9% (95%CI=19.81-39.40) and 17.8% of PChE levels (95%CI=10.52-27.26). To predict Parkinsonism, AChE, and PChE level, with a cutoff score of 5 or higher there had to be a sensitivity of 0.31, specificity of 1.00, positive predictive value (PPV) of 1.00 and negative predictive value (NPV) of 0.78 for AChE. While PChE, the score value of 5 or more had a sensitivity of 0.19, specificity of 0.93, PPV of 0.38 and NPV of 0.84. Conclusion. This study described an association between pesticides exposure and Parkinsonism. The questionnaire appears to be useful for Thai agriculturists as a screening tool for Parkinsonism and cholinesterase levels regarding to pesticides exposure.
Źródło:
Roczniki Państwowego Zakładu Higieny; 2015, 66, 1
0035-7715
Pojawia się w:
Roczniki Państwowego Zakładu Higieny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new freshwater basal eucryptodiran turtle from the Lower Cretaceous of Spain
Autorzy:
Perez-Garcia, A.
De La Fuente, M.S.
Ortega, F.
Powiązania:
https://bibliotekanauki.pl/articles/20420.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
new genus
new species
freshwater turtle
eucryptodiran turtle
Lower Cretaceous
Cretaceous
paleontology
Spain
Testudines
Eucryptodira
Barremian
Las Hoyas
Opis:
A freshwater turtle from the lithographic limestone of Las Hoyas (Barremian of Cuenca, Spain) is described as a new genus and species of Eucryptodira, Hoyasemys jimenezi. The holotype consists of the skull, lower jaw, carapace, plastron, vertebral column, pectoral and pelvic girdle remains, and foreand hindlimbs. Hoyasemys jimenezi gen. et sp. nov. is characterized by three pairs of blind oblique depressions on the ventral surface of the basisphenoid, and a character combination composed, among others, of the articulation between the fourth and fifth cervical vertebrae through a cotyle in the fourth and a condyle in the fifth, amphicoelous caudal centra, and most digits of manus and pes with three elongated phalanges. This study allows clarification of the systematic position of a species of uncertain affinity often identified as “chelydroid” in appearance. A phylogenetic analysis shows Hoyasemys jimenezi gen. et sp. nov. forms a monophyletic group with Judithemys sukhanovi, Dracochelys bicuspis, Sinemys lens, and Ordosemys leios, collectively the sister group of crown Cryptodira.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł

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