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Wyszukujesz frazę "Umar, A." wg kryterium: Autor


Wyświetlanie 1-9 z 9
Tytuł:
Effects of viscous dissipation and wall conduction on steady mixed convection Couette flow of heat generating / absorbing fluid
Autorzy:
Ajibade, A. O.
Umar, A. M.
Powiązania:
https://bibliotekanauki.pl/articles/264671.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
strumień masy
kanał pionowy
konwekcja mieszana
mixed convection
viscous dissipation
vertical channel
boundary thickness
mass constant flux
Opis:
This article theoretically investigated mixed convection flow of heat generating/absorbing fluid in the presence of viscous dissipation and wall conduction effects. The flow is considered to be steady in a vertical channel with some boundary thickness. One of the plates is heated while the other is kept at ambient temperature. The governing flow equations were solved analytically using Homotopy Perturbation Method (HPM). The influences of the governing parameters were captured in graphs, tables and a table was constructed for validation of the work. It is worthwhile to stress that, both the velocity and temperature profiles decrease near the heated plate with an increase in boundary thickness (d) while the reverse cases were observed toward the cold plate. The velocity profile increases near the heated plate with increase in mixed convection parameter (Gre) and decreases towards the cold plate. Rate of heat transfer has been observed to decrease with increase in boundary plate thickness (d) while the critical value of (Gre) increases with growing boundary plate thickness. The study therefore established the importance of boundary plate thickness in mixed convection investigation.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 4; 12-35
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Annealing Effect on the Morphology of Inkjet Printed Polymer:Fullerene Composites Solar Cells
Autorzy:
Fauzia, V.
Umar, A.
Salleh, M.
Yahaya, M.
Powiązania:
https://bibliotekanauki.pl/articles/1490940.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
88.40.jr
81.05.Fb
Opis:
One of critical factor in determining the performance of solar cells is the morphology of the active layer. The drying process of the active layer prepared by inkjet printing technique plays a key role in obtaining high quality surface morphology. This paper reports the effect of thermal annealing on the morphology of printed active layer. The printed active layer is a blend of poly(3-octylthiophene-2,5-diyl) and (6,6)-phenyl $C_{71}$ butyric acid methyl ester dissolved in a mixture of dichlorobenzene:mesitylene. The printed films were then annealed at three different temperatures, namely 120, 140, and 160C for 60 min to obtain the best performance of solar cells. It was found that the performance of solar cells strongly depends on the annealing temperature. The devices with the active layer annealed at 140C exhibits the highest performance with short circuit current density and open circuit voltage as high as 2.88 μA/$cm^2$ and 0.85 V, respectively. The effect of annealing on the properties of printed active layer will be discussed.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 155-157
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electroluminescence Enhancement of Polymer Light Emitting Diodes Through Surface Plasmons by Ag Nanoplates
Autorzy:
Aziz, T.
Salleh, M.
Bakar, N.
Umar, A.
Rahman, M.
Powiązania:
https://bibliotekanauki.pl/articles/1186484.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Mf
Opis:
This paper reports a study on the surface plasmon effect of Ag nanoplates on electroluminescent property of polymer light emitting diodes. The diode is a single layer light emitting device made of poly [9,9-di-(2-ethylhexyl)-fluorenyl-2,7-diyl] (PEHF). 5 wt.% of Ag nanoplates were incorporated into the PEHF layer. The results showed that the electroluminescence intensity of the diodes is increased by 51.85%, compared with the device without the Ag nanoplates. The enhancement is due to the coupling process between the Ag surface plasmon with the emission light from the PEHF. The occurrence of the coupling process was proved firstly based on the fact that the exciton lifetime of the PEHF:Ag layer is shorter than that without Ag, as measured by time-resolved photoluminescence spectroscopy. Secondly, the PEHF photoluminescence peak at 425 nm is overlaping with the surface plasmon absorption peak of Ag nanoplates.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 711-713
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Laser stimulated nonlinear optics of Ag nanoparticle-loaded poriferous TiO2 microtablet
Autorzy:
Nafisah, S.
Saad, S. K. M.
Umar, A. A.
Plucinski, K.
Lis, M.
Maciaga, A.
Miedzinski, R.
Powiązania:
https://bibliotekanauki.pl/articles/173662.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Ag-loaded poriferous TiO2 microtablets
photoinduced second harmonic generation
Opis:
The studies of the photoinduced second harmonic generation were performed for the Ag-loaded poriferous TiO2 microtablets deposited on an ITO substrate. The poriferous TiO2 microtablets on a pre-cleaned ITO substrate (Kaivo, China, sheet resistance of ca. 10 Ω/square) were prepared by simply immersing the ITO substrate vertically into the growth solution that contains 5 ml of 0.5 M (NH4)2TiF6 (Sigma-Aldrich) and 5 ml of 1.0 M H3BO3 (R.M. Chemicals) for 15 h at room temperature. The samples were obtained from the growth solution with concentration of 0.4, 0.5 and 0.6 M. We have found that maximal second harmonic generation signal was achieved for the samples with concentration 0.5 M.
Źródło:
Optica Applicata; 2015, 45, 2; 263-271
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of cytotoxic ions sequestration as salt tolerant indicators in tomato (Solanum lycopersicum L.)
Autorzy:
Umar, J.
Aliyu, A.A.
Kasim, S.
Lawal, A.
Powiązania:
https://bibliotekanauki.pl/articles/2049702.pdf
Data publikacji:
2018
Wydawca:
Fundacja na Rzecz Młodych Naukowców
Tematy:
tomato
Solanum lycopersicum
sequestration
salt tolerance
genetic diversity
cytotoxics
Opis:
This study determines the genetic diversity of 20landraces and released cultivars of tomato collected from Market places and research institutes in Nigeria. Ion homeostasis and cytotoxic sequestration significantly (P>0.05) affected by concentration of salt in a concentration dependent manner. Accumulation of Na+, Cl-, K+ and Ca2+ ions increased in salt treated groups (30 and 60 mg/L of NaCl) as compared to controls. Potassium ion uptake was salt concentration dependent in all cultivars; the magnitude of Na+/K+ levels is lower in released cultivars than in landraces cultivars. It can be concluded from these findings that Na+ was compartmentalized both in tomato by membrane transporters and that low level was a good indicator of salt tolerant in tomato genotype studied.
Źródło:
Environment, Earth and Ecology; 2018, 2, 1; 28-33
2543-9774
2451-4225
Pojawia się w:
Environment, Earth and Ecology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative Proximate Analysis of Five Commercially Sold Maggi as Condiments in Gwagwalada, North Central, Nigeria
Autorzy:
Adeeko, E. L.
Shittu, G. A.
Adeeko, T. O.
Umar, M.
Powiązania:
https://bibliotekanauki.pl/articles/1075587.pdf
Data publikacji:
2019
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
bioaccumulation
bouillon
condiments
heavy metal
mineral elements
proximate
Opis:
Determination of the proximate, nutritionally valuable mineral in five samples of food seasonings label as, A, B, C, D, & E food condiments readily consumed in Nigeria were obtained from Gwagwalada Central Market Abuja. Investigating the concentrations of some mineral elements such as, iron (Fe), zinc (Zn), and two heavy metals, cadmium (Cd) and lead (Pb) were carried out using AA320N Atomic Absorption Spectrophotometer (AAS) after acid digestion with 2:1 HNO3/HClO4. The result shows that all samples contained high levels of protein (13.63% ±0.53%) with mean value moisture, ash, fat, fiber, and carbohydrate for all samples levels being (3.94%±0.64%), (57.51% ±4.27%), (5.11% ±0.20%), (0.02% ±0.00%) and (18.41% ±0.41%) respectively. Sample D has high Fe concentration with (0.04 ±0.01 μg/g) and Sample B & C has low Fe concentration with (0.01 ±0.00 μg/g). Sample D & E has high Zn concentration with (0.03 ±0.01 μg/g) and sample A, B & C has low Zn concentration with (0.02 ±0.01 μg/g). In cadmium, sample A has the high concentration (0.03±0.01μg/g), sample B & D has the low Cd concentration (0.02 ±0.00 μg/g). Sample D had the high Pb concentration (0.05 ±0.00 μg/g), sample C had the low Pb concentration (0.02±0.01 μg/g). In conclusion, Fe, Zn, Cd and Pb were both present in low concentrations in all the samples analyzed. The presence of Cd and Pb in the food seasonings even at low concentration could prove fatal through bioaccumulation. The low level of the toxic metals, Pb and Cd indicates that these products meet the safe limits specified by most food standards.
Źródło:
World Scientific News; 2019, 122; 183-192
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Estimation of technical inefficiency and production risk among small scale maize farmers in the Federal Capital Territory (FCT) Abuja, Nigeria
Szacowanie niewydolności technicznej i ryzyka produkcyjnego wśród hodowców kukurydzy na małą skalę na Federalnym Terytorium Stołecznym Abuja, Nigeria
Autorzy:
Okeke, N. Immaculate
Umar, H. Suleiman
Girei, A. Abdulhamid
Ibrahim, H. Yusuf
Powiązania:
https://bibliotekanauki.pl/articles/2216503.pdf
Data publikacji:
2020
Wydawca:
Politechnika Bydgoska im. Jana i Jędrzeja Śniadeckich. Wydawnictwo PB
Tematy:
consumption
income
maize production
output
dochody
konsumpcja
kukurydza
produkcja
Opis:
Background. Estimation of technical inefficiency and Production risk play a key role in farmers’ decisions pertaining to input allocation and subsequent output. The study provided empirical evidence on technical inefficiency and associated production risk among small scale maize farmers in the Federal Capital Territory (FCT) Abuja, Nigeria. Material and methods. A multistage sampling technique was adopted in the selection of 154 respondents. Data were analyzed using descriptive statistics and a stochastic frontier function with a heteroskedastic error structure. Results. The results show that farm size and agrochemicals significantly influenced maize production at (P < 0.01) and (P < 0.1), respectively. An increasing return to scale in Maize production was observed in the study area. There was significant evidence of production risk associated with inputs used in maize production. From among the production inputs considered in the study, only seed was found to significantly reduce risk (P < 0.01). The technical inefficiency of farmers in the area ranged between 0.06-0.99 with a mean inefficiency of 0.27 (27%). Conclusion. On average 27% of the output was lost as a result of technical inefficiency in maize production and production risk could be reduced significantly if an additional quantity of maize seed is planted per hectare.
Oszacowanie niewydolności technicznej i ryzyka produkcyjnego odgrywa kluczową rolę w decyzjach rolników dotyczących alokacji nakładów i późniejszej wydajności. Badanie dostarczyło empirycznych dowodów na nieefektywność techniczną i związane z nią ryzyko produkcyjne wśród drobnych rolników zajmujących się uprawą kukurydzy na Federalnym Terytorium Stołecznym Abudża w Nigerii. Przy wyborze 154 respondentów przyjęto wielostopniową technikę doboru próby. Dane analizowano za pomocą statystyki opisowej i stochastycznej funkcji granicznej. Wyniki pokazują, że wielkość gospodarstwa i substancje agrochemiczne znacząco wpłynęły na produkcję kukurydzy. Na badanym obszarze zaobserwowano powrót do coraz większej skali w produkcji kukurydzy. Istniały istotne dowody na ryzyko produkcyjne związane z materiałami używanymi do produkcji kukurydzy. Spośród rozważanych w badaniach nakładów produkcyjnych stwierdzono, że tylko nasiona istotnie obniżały ryzyko (P < 0,01). Nieefektywność techniczna rolników na tym obszarze wahała się między 0,06 a 0,99; średnia nieefektywność wynosiła 0,27. Średnio 27% produkcji zostało utracone w wyniku technicznej niewydolności w produkcji kukurydzy, a ryzyko produkcyjne mogłoby zostać znacznie zmniejszone, gdyby wysiano dodatkową ilość nasion kukurydzy na hektar.
Źródło:
Acta Scientiarum Polonorum. Agricultura; 2020, 19, 3; 147-155
1644-0625
Pojawia się w:
Acta Scientiarum Polonorum. Agricultura
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Knowledge and attitude of primary healthcare workers towards rational prescription of artemisinin-based combination therapy in the treatment of uncomplicated malaria in Ondo State, Southwestern Nigeria
Autorzy:
Oyinaka, B.D.
Umar, N.M.
Aminu, N.
Akinleye, C.A.
Nuhu, T.
Powiązania:
https://bibliotekanauki.pl/articles/2098244.pdf
Data publikacji:
2020
Wydawca:
Instytut Medycyny Wsi
Tematy:
Primary Health Care
worker
artemisinin-based combination therapy
knowledge
Ondo State
Nigeria
Opis:
Introduction and objective. For an effective and desired outcome of therapy to be achieved, the technical capacity of the healthcare worker is a key factor. The aim of the study is to assess knowledge and attitudes of primary healthcare (PHC) workers towards rational artemisinin-based combination therapy (ACT) prescribed in the treatment of uncomplicated malaria. Materials and method. This is a descriptive cross-sectional survey in which a self-administered structured questionnaire was used. A combination of stratified and multistage sampling techniques where utilized in the selection of the healthcare workers (HCWs). Results. Of the 422 respondents, 100 (23.7%) were males and 322 (76.3%) were females. Respondents with less than five years in practice accounted for 36%, while 64% had six years and above of practice. Community health extension workers (CHEW) accounted for 54%, while 46% were either community health officers (CHO), nurses, midwives, Bachelors of Science (BSc) in community health, or with other qualifications. A total of 390 (92.4%) were aware of the availability of ACTs and used the malaria treatment protocols, whereas 28 (6.6%) still used monotherapy for simple malaria treatment, and 2.7% did not use any form of test before initiating treatment. Co-administration of non-ACTs with ACTs accounted for 12%, with 88% prescribing paracetamol with ACTs. 67% of the respondents required capacity building in rational ACT use. Conclusion. The majority of the respondents had the requisite knowledge and skills coupled with positive attitudes in prescribing ACTs. Some respondents could not distinguish between an ACTs and a monotherapy. This may affect the exact application of the malaria treatment protocols, especially at the PHC level.
Źródło:
Journal of Pre-Clinical and Clinical Research; 2021, 15, 1; 5-14
1898-2395
Pojawia się w:
Journal of Pre-Clinical and Clinical Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Signatures of Late Neoproterozoic Gondwana assembly and Maronian glaciation in Lesser Himalaya: a palaeogeographical and stratigraphical approach
Autorzy:
Umar, M.
Betts, P.
Khan, M. M. S.
Sabir, M. A.
Farooq, M.
Zeb, A.
Jadoon, U. K.
Ali, S.
Powiązania:
https://bibliotekanauki.pl/articles/139442.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Neoproterozoic
palaeogeography
Glaciation
Rodinia break-up
Lesser Himalaya
neoproterozoik
paleogeografia
zlodowacenie
Rodinia
rozpad
Himalaje Małe
Opis:
Stratigraphical and sedimentological analyses of Late Neoproterozoic successions in Lesser Himalaya are combined herein with palaeogeographical considerations and comparisons with equivalent successions in India and South China. The succession starts with the Hazara Formation, which contains complete and incomplete Bouma sequences suggesting its deposition in deep marine turbidite settings. The overlying Tanawal Formation, rich in massive sandstone, shale and siltstone, was deposited in shallow marine conditions, as indicated by the presence of parallel lamination, large scale tabular, trough cross- and hummocky cross-stratifications. The Tanawal Formation facies shift laterally from proximal (south-southeast) to distal (north-northwest). The glaciogenic Tanaki Boulder Bed, overlying the Tanawal Formation, was deposited during the Maronian glaciation. It is equivalent to the Blaini Formation of India, and to the Sinian diamictites of South China. The Abbottabad Formation of Cambrian age overlies the Tanaki Boulder Bed, and is composed of dolomite, chert nodules and phosphate-rich packages; similar successions are documented in India and South China at the same stratigraphical interval. The similarities of the Neoproterozoic successions of Lesser Himalaya (both in Pakistan and India) and South China suggests their possible proximity during the break-up of Rodinia and the assembly of the Gondwana Supercontinent.
Źródło:
Acta Geologica Polonica; 2015, 65, 1; 1-19
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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