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Wyświetlanie 1-25 z 46
Tytuł:
Copper (II) Oxide particles as Adsorbent for Removal of Alkali Blue; Isotherm and Kinetic Studies
Autorzy:
Ibrahim, M. A.
Ibrahim, M. B.
Powiązania:
https://bibliotekanauki.pl/articles/1158766.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Adsorption
Copper (II) Oxide particles
FTIR
Isotherm
Kinetics
Opis:
Adsorption behaviour of copper (II) oxide particles (CuO-Ps) for the removal of Alkali Blue (AB) was studied. Different adsorption variables such as contact time, initial concentration and pH for the adsorption process were investigated by batch adsorption studies. FTIR was carried out to determine the functional groups present at the surface of the particle with functional groups such as –OH, C=C, C-H, C≡C detected. The percentage removal and optimum contact time for the removal of AB was 84.8% at 10 min. The experimental isotherms data were analyzed using Langmuir, Temkin, Freundlich and Dubinin-Radushkevich (D-R) isotherms and it was observed that AB fits closely to Langmuir with R2 value of 0.884. Kinetics studies shows that the adsorption process fits better to pseudo-second order with the experimental values of qe 4.242 been closer to the calculated values of the qe 4.108. Effect of pH shows that it adsorb better at the initial pH of 5.30. Lower value of mean square energy of 0.707 kJ/mol indicates that the adsorption process is physical. The results indicated that copper (II) oxide particle can be used as a low-cost adsorbent for the removal of AB from aqueous solutions.
Źródło:
World Scientific News; 2018, 114; 208-217
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
In vitro culture of big-sage (Lantana camara L.) plant
Autorzy:
Ibrahim, M.A.
Sabty, M.Z.
Mussa, S.H.
Powiązania:
https://bibliotekanauki.pl/articles/12710538.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Przyrodniczy w Lublinie. Wydawnictwo Uniwersytetu Przyrodniczego w Lublinie
Opis:
The study was conducted to mass micropropagation of big sage (Lantana camara L.) plant by shoot multiplication technique. The treatments 2.22 and 2.66 µmol·L⁻¹ BA gave the highest significant increase in the percentage of response to shoot multiplication and number of shoots per explant compared to the other treatments as reached 96.70% and 100.00% and 4.33 and 6.00 shoots, respectively. The results showed that these two treatments did not differ significantly between them. While the 1.33 µmol·L⁻¹ BA gave the lowest values in the percentage of response to shoot multiplication and number of shoots per explant were 80.00% and 2.00 shoots per explant, respectively. The MS medium supplemented with 4.30 or 5.37 µmol·L⁻¹ NAA gave a high response to root formation, number of roots per shoot and root length. While the MS medium supplemented with 6.44 or 7.52 µmol·L⁻¹ NAA gave low values in these characteristics. The MS medium with 2.22 or 2.66 µmol·L⁻¹ concentration of BA or 7.52 µmol·L⁻¹ concentration of NAA recorded the highest significant increase in the percentage of response to callus formation. While the MS medium supplemented with 1.33 µmol·L⁻¹ BA or 4.30 µmol·L⁻¹ NAA gave less response to the callus formation.
Źródło:
Acta Scientiarum Polonorum. Hortorum Cultus; 2020, 19, 2; 67-73
1644-0692
Pojawia się w:
Acta Scientiarum Polonorum. Hortorum Cultus
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Minerals content, essential oils composition and physicochemical properties of Citrus jambhiri Lush. (Rough Lemon) from the Sudan
Autorzy:
Mohammed, A. M. H.
Ibrahim, M. A
Omran, A. A.
Mohamed, E. M.
Elsheikh, S. E. M.
Powiązania:
https://bibliotekanauki.pl/articles/412508.pdf
Data publikacji:
2013
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Citrus jambhiri
Rutaceae
atomic absorption spectroscopy (AAS)
Flame Atomic Emission Spectroscopy (FAES)
metal content
essential oils
Opis:
Minerals content of Citrus jambhiri (rough lemon) fruit was qualitatively and quantitatively analyzed using atomic absorption spectroscopy (AAS) and flame atomic emission spectrometry (FAES). The peel, moisture and ash contents of rough lemon were found to be 18.35 %, 23.75 % and 2.04 % respectively. Vitamin C (ascorbic acid) of rough lemon juice was found to be 70.0 mg/100 g. The chemical composition of essential oil of rough lemon peel was determined. The major compound was found to be limonene (84.5 %) followed by sabinene, β-myrcene, α-terpineol, 1,3-tetradecadiene and linalool.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2013, 9, 1; 25-30
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design of a Solar Powered Reverse Osmosis System in Egypt
Autorzy:
Ibrahim, Said M. A.
Shabak, Ahmed G. M.
Powiązania:
https://bibliotekanauki.pl/articles/2052247.pdf
Data publikacji:
2021
Wydawca:
Politechnika Koszalińska. Wydawnictwo Uczelniane
Tematy:
reverse osmosis
photovoltaic
total dissolved solids
TDS
pvro
desalination
odwrócona osmoza
fotowoltaika
całkowita ilość rozpuszczonych w płynie substancji
odsalanie
Opis:
Scarcity of fresh water, forced many countries to get their water needs, or part of it, by means of saline water desalination. Reverse osmosis (RO) systems are useful tools in this concern. In case the grid electricity is not available or costly, photovoltaic (PV) power is necessary to derive RO systems. The present paper is concerned with providing a methodology for complete sizing and design of a photovoltaic reverse osmosis (PVRO) system in Egypt. Egypt has very favorable solar energy. A computer program was constructed to solve the mathematical equations of the model to get the numerical values. The program is capable of calculating the solar irradiation for any city in Egypt. Calculations and selection of the RO system with all connected pumps, the peak PV power needed, and the actual PV area were performed for different water demands ranging from 1-100 m3/day, and various water total dissolved solids (TDSs) of 5000, 15000, and 30000 mg/l. The cost of the complete PVRO system was also determined. The concern of the paper is related to water desalination and solar energy, which are responsible for our existence. The work also aims toward sustainable and clean environment via utilizing solar energy.
Źródło:
Journal of Mechanical and Energy Engineering; 2021, 5, 2; 125-140
2544-0780
2544-1671
Pojawia się w:
Journal of Mechanical and Energy Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Non-linearity on pull-out test of cohesive soil using low tensile strengths of geogrids
Autorzy:
Widodo, S.
Ibrahim, A. M.
Powiązania:
https://bibliotekanauki.pl/articles/115809.pdf
Data publikacji:
2014
Wydawca:
Fundacja na Rzecz Młodych Naukowców
Tematy:
pull-out test
tensile strength
geogrid
ITD
non-linear
Opis:
Influence of geosynthetics inserted into cohesive granular soil was obviously investigated using geosynthetics-soil-interaction-testing device (ITD). Observations were already made during undertaking pull-out test, and then the results revealed that a correlation between shear stress and normal stress exhibits non-linear behaviour. In this paper, three approaches of trend-lines namely linear, logarithmic, and polynomial were compared. From analysis, polynomial trend line gave the best correlation among others. The final equation is very important part when estimating more accurate values of cohesion and friction angle design purpose.
Źródło:
Challenges of Modern Technology; 2014, 5, 1; 34-37
2082-2863
2353-4419
Pojawia się w:
Challenges of Modern Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Irrigation and fertigation scheduling under drip irrigation for maize crop in sandy soil
Autorzy:
Ibrahim, M.M.
El-Baroudy, A.A.
Taha, A.M.
Powiązania:
https://bibliotekanauki.pl/articles/26207.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
irrigation
fertigation
drip irrigation
maize
yield
water productivity
crop
sandy soil
field experiment
Źródło:
International Agrophysics; 2016, 30, 1
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Three-phases bubble column to polyethylene terephthalate depolymerization for cement mortar composites improvement
Autorzy:
Hameed, A. M.
Alzuhairi, M.
Ibrahim, S. I.
Powiązania:
https://bibliotekanauki.pl/articles/2172162.pdf
Data publikacji:
2022
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
depolymerization
DPET
plastic waste
bubble column
mortar
water absorption
flexural strength
depolimeryzacja
odpady z tworzyw sztucznych
kolumna barbotażowa
zaprawa
absorpcja wody
wytrzymałość na zginanie
Opis:
Purpose This paper aims to prepare depolymerized polyethylene terephthalate (DPET) powder from recycled plastic water bottles. Adding this DPET powder to the cement mortar was also studied. Design/methodology/approach The adopted PET depolymerization process includes the usage of both ethylene glycol (EG) as solvent and nano-MgO as a catalyst. A bubble column reactor was designed for this process. Five different mortar groups were made; each has different DPET content of 0%, 1%, 3%, 6% and 9% as a sand replacement. The flexural strength test and the water absorption measurement are done after two curing periods: 7 and 28 days. Findings The research finding demonstrated that the flexural strength of mortar was reduced by increasing the DPET powder percentage and the maximum dropping was 15% when 9% of DPET was added. The ability of the mortar to absorb the water was reduced by 14.5% when DPET powder was 9%. The mortar microstructure is featured with fewer cavities and porosity. Research limitations/implications This work’s employed bubble column technique is limited only to the laboratory environment and needs to be scaled up within industrial mass production. For future research, it is suggested to decrease depolymerization time by using smaller pieces of plastic water bottle waste and trying other types of nanocatalyst. Practical implications The modified mortar can be utilized in areas where moisture, rainfalls, and sanitation systems exist. Originality/value The article claims that depolymerized waste PET improves chemical process efficiency by lowering reaction time and improving mass and heat transfer rates. Besides, this approach saves money. It is found out that the depolymerized plastic waste is much more functional due to its high cohesion capability than being used as small PET pieces.
Źródło:
Journal of Achievements in Materials and Manufacturing Engineering; 2022, 112, 1; 5--12
1734-8412
Pojawia się w:
Journal of Achievements in Materials and Manufacturing Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Parametric study simulation of axially loaded ored pile using finite element ode—Plaxis Software on subsurface soils Khartoum area-Sudan
Autorzy:
Ibrahim, A. M.
Widodo, S.
Hong, S.
Powiązania:
https://bibliotekanauki.pl/articles/115670.pdf
Data publikacji:
2012
Wydawca:
Fundacja na Rzecz Młodych Naukowców
Tematy:
bored pile
finite code
plaxis software
Opis:
The diversity and complexity of subsurface soil in studied area consisting of alluvial deposits cause many diffi culties for foundation engineering. Therefore, a solution is needed for foundation in this problematic soil. In Sudan, raft foundation represents the basic and most widespread shallow foundation method for engineering structure except for bridges where the pile foundation is used. In recent years, after the discovery of petroleum in Sudan, a major advance in piling technology is needed due to intensive building of large numbers of precast high-rise tower. This paper used Plaxis software to understand the behavior of axially loaded bored pile using different loads, lengths and diameters of piles. In this paper a comprehensive analytical study using fi nite element analysis is presented and parametric study of pile under vertical load is performed. The analytical and quantitative analysis in this study shows useful understanding of the behavior of bored pile.
Źródło:
Challenges of Modern Technology; 2012, 3, 3; 33-38
2082-2863
2353-4419
Pojawia się w:
Challenges of Modern Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On a mixed-type integral equation and fractional-order functional differential equations
Autorzy:
El-Sayed, A. M. A.
Sherif, Nagwa
Ibrahim, I. A.
Powiązania:
https://bibliotekanauki.pl/articles/745693.pdf
Data publikacji:
2005
Wydawca:
Polskie Towarzystwo Matematyczne
Tematy:
Nonlinear functional integral equation
fractional calculus
Volterra operator
mixed type integral equation
Schauder fixed point theorem
Opis:
In this paper we study the existence of solution of a nonlinear integral equation of (mixed type) Volterra-Fredholm type. As an application we prove the existence of solution of an initial value problem of fractional order in the space of Lebesgue integrable functions on the interval \([0, 1]\).
Źródło:
Commentationes Mathematicae; 2005, 45, 2
0373-8299
Pojawia się w:
Commentationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of integral antioxidants capacity in Syrian Hawthorn fruits and flowers using photochemiluminescence assay
Oznaczanie ogólnej zdolności przeciwutleniającej w owocach i kwiatach głogu z Syrii przy użyciu metody fotochemiluminescencyjnej
Autorzy:
Zayzafoon, G.
Odeh, A.
Ibrahim, M.
Allaf, A.W.
Powiązania:
https://bibliotekanauki.pl/articles/71723.pdf
Data publikacji:
2010
Wydawca:
Instytut Włókien Naturalnych i Roślin Zielarskich
Opis:
Syrian flora is very well known of its diversity and richness. It contains a large number of medicinal and aromatic species. There are many different hawthorn Crataegus: sinaica, aronia, monogyna and azorolus available in Syria which is mainly located in the western and southern part of the country. Most of these Syrian species are used in folk and in traditional medical care. They are taken in the form of herbal tea to contradict cough, flu and cold. There is no any scientific information available on the antioxidant properties of Syrian hawthorn medicinal plant. Therefore, the assessment of such properties remains an interesting and useful task, particularly for finding a new natural source of antioxidants available in Syria. Therefore, the integral antioxidants, IA of Syrian hawthorn fruits and flowers in five different sites as ascorbic acid equivalents have been carried out using photochemiluminescence, PCL assay of measurements for the first time. By means of a PCL assay, it was possible to assess the integral antioxidant (IA ) using this accurate and simple method, the highest antioxidant capacity values of hawthorn as ascorbic acid equivalents were found in the fruits of Bi’r Al-ajam and Al-Haffa sites which have values of 1444.82 and 483.44 (nmol/g), for C. monogyna and C. aronia cataegus, respectively. The highest fractions of antioxidant components are mainly due to the existence of catechin and flavonoids in both Syrian hawthorn fruit and flowers. Other chemical constituents like elemicin, sorbistat, polygalitol and homocatechol are found in Syrian hawthorn fruit and flowers. The measured values are considered to be the highest among countries of the region.
Flora Syrii wykazuje dużą różnorodność. W Syrii występuje wiele gatunków z rodzaju głóg Crataegus: sinaica, aronia, monogyna i azorolus. Są one głównie spotykane w zachodniej i południowej części kraju. Wiele z syryjskich gatunków z rodzaju Crataegus jest używanych w medycynie ludowej i tradycyjnej w postaci herbatek ziołowych w leczeniu kaszlu, grypy i przeziębienia. Brak jest naukowych doniesień na temat właściwości przeciwutleniających syryjskich gatunków głogu. Z tego powodu badanie tych właściwości jest interesujące i użyteczne, zwłaszcza w celu znalezienia nowych źródeł przeciwutleniaczy dostępnych na terenie Syrii. W artykule przedstawiono oznaczenia sumy antyoksydantów (ang. Integral antioxidants, IA ) w przeliczeniu na kwas askorbinowy, wykonane dla syryjskich głogów (owoców i kwiatów), zebranych z pięciu różnych stanowisk. Oznaczenia te po raz pierwszy wykonane były przy zastosowaniu metody fotochemiluminescencyjnej (ang. PCL assay). Stwierdzono, że najwyższa wartość zdolności przeciwutleniających w przeliczeniu na kwas askorbinowy została oznaczona dla owoców ze stanowisk Bi’r Al.-ajam i Al.-Haffa, dla których wartości te wyniosły odpowiednio 1444,82 i 483,44 (nmol/g). Otrzymane wartości można uważać za najwyższe w stosunku do wartości podawanych w innych państwach w tym regionie.
Źródło:
Herba Polonica; 2010, 56, 2
0018-0599
Pojawia się w:
Herba Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anti-HIV activity of some natural phenolics
Autorzy:
El-Ansari, M.A.
Ibrahim, L.F.
Sharaf, M.
Powiązania:
https://bibliotekanauki.pl/articles/2049059.pdf
Data publikacji:
2020
Wydawca:
Instytut Włókien Naturalnych i Roślin Zielarskich
Tematy:
medicinal plants
phenolics
AIDS
anti-HIV activity
mechanism of action
rośliny lecznicze
związki fenolowe
działanie anty-HIV
mechanizm działania
Opis:
Acquired immunodeficiency syndrome (AIDS) is an immunosuppressive disease caused by human immunodeficiency virus (HIV). The urgent need for searching novel anti-HIV/AIDS medicines is a global concern. So far, a lot of medicinal and aromatic plants (MAPs) have been analyzed to select those that could assist in the prevention and/or amelioration of the disease. Among biologically active compounds present in these plants, one of the most promising group are phenolics. The purpose of this article was to report antiHIV activity of selected phenolic compounds of plant origin.
Źródło:
Herba Polonica; 2020, 66, 2; 34-43
0018-0599
Pojawia się w:
Herba Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of genetic algorithm for optimization the safety system of the nuclear reactor
Autorzy:
El-Sayed Wahed, M.
Ibrahim, W. Z.
Effat, A. M.
Powiązania:
https://bibliotekanauki.pl/articles/146492.pdf
Data publikacji:
2009
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
genetic algorithm
non-dominated sorting
chimney water injection system (CWIS)
Egypt nuclear
Opis:
The purpose of this paper is to present an approach to optimization in which every target is considered as a separate objective to be optimized. Multi-objective optimization is a powerful tool for resolving conflicting objectives in engineering design and numerous other fields. One approach to solve multi-objective optimization problems is the non-dominated sorting genetic algorithm (NSGA). Genetic algorithm (GA) was applied in regarding the choice of the time intervals for the periodic testing of the components of the chimney water injection system (CWIS) of the 22 MW open pool multipurpose reactor (MPR), ETRR-2, at the Egyptian Atomic Energy Authority, has been used as a case study.
Źródło:
Nukleonika; 2009, 54, 1; 51-56
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Genetic algorithms and neural networks for solving water quality model of the Egyptian research reactor
Autorzy:
El-Sayed Wahed, M.
Ibrahim, W. Z.
Effat, A. M.
Powiązania:
https://bibliotekanauki.pl/articles/148150.pdf
Data publikacji:
2009
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
genetic algorithm
neural networks
model calibration
water distribution system
water quality model
Opis:
The second Egyptian research reactor ETRR-2 became critical on 27th November, 1997. The National Center of Nuclear Safety and Radiation Control (NCNSRC) has the responsibility for the evaluation and assessment of safety of this reactor. Modern managements of water distribution system (WDS) need water quality models that are able to accurately predict the dynamics of water quality variations within the distribution system environment. Before water quality models can be applied to solve system problems, they should be calibrated. The purpose of this paper is to present an approach which combines both macro and detailed models to optimize the water quality parameters. For an efficient search through the solution space, we use a multi-objective genetic algorithm which allows us to identify a set of Pareto optimal solutions providing the decision maker with a complete spectrum of optimal solutions with respect to the various targets. This new combinative algorithm uses the radial basis function (RBF) metamodeling as a surrogate to be optimized for the purpose of decreasing the times of time-consuming water quality simulation and can realize rapidly the calibration of pipe wall reaction coefficients of chlorine model of large-scaled WDS.
Źródło:
Nukleonika; 2009, 54, 4; 239-245
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mitigation of salinity stress effects on growth, physio-chemical parameters and yield of snapbean (Phaseolus vulgaris L.) by exogenous application of glycine betaine
Autorzy:
Desoky, E-S.M.
Ibrahim, S.A.
Merwad, A-R.M.
Powiązania:
https://bibliotekanauki.pl/articles/11220.pdf
Data publikacji:
2019
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Źródło:
International Letters of Natural Sciences; 2019, 76
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effectiveness factor of two-dimensional ring-shaped catalyst pellets
Autorzy:
Asif, M.
Ibrahim, A. A.
Mohammed, Y. A.
Al-Ghurabi, E. H.
Powiązania:
https://bibliotekanauki.pl/articles/780040.pdf
Data publikacji:
2017
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
hollow catalyst pellet
effectiveness factor
Thiele modulus
convergence behavior
analytical solution
Opis:
The use of hollow catalytic support improves the utilization of the catalytic material because of the absence of the pellet core, and moreover ensures low reactor pressure drop owing to enhanced bed voidage. In this study, the expressions for the efficient computation of the effectiveness factor are derived for a ring-shaped catalyst pellet undergoing first-order irreversible reaction. The methodology consists of using solutions of one-dimensional problems to remove non-homogeneous boundary conditions. The expressions obtained exhibit significantly faster convergence behavior than those reported in literature. The shape parameters, namely, the height-to-diameter ratio and the inner-to-outer radii ratio, significantly affect the catalyst utilization, such that several-fold improvement in the effectiveness factor is achievable.
Źródło:
Polish Journal of Chemical Technology; 2017, 19, 3; 99-105
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and properties of vinylpyrrolidone/ (trimethoxysilyl)propyl methacrylate gels containing different amounts of crosslinking agent
Synteza i właściwości żelu N-winylopirolidon/metakrylan3-(trimetoksysililo)propylu z różną zawartością czynnika sieciującego
Autorzy:
Mohammed, A. H.
Ahmad, M. B.
Ibrahim, N. A.
Zainuddin, N.
Powiązania:
https://bibliotekanauki.pl/articles/947044.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
Tematy:
high conversion copolymers
swelling parameters
mechanical properties
oxygen permeability
crosslinking density
kopolimery o wysokim stopniu konwersji
parametry pęcznienia
właściwości mechaniczne
przepuszczalność tlenu
gęstość sieciowania
Opis:
High conversion copolymers containing 90 wt % of N-vinylpyrrolidone (NVP) and 10 wt % of 3-(trimethoxysilyl)propyl methacrylate (TMSPM) with 0, 1, 2, 3 and 4 wt % (in conversion to mass of NVP/TMSPM) of ethylene glycol dimethacrylate (EGDMA) as crosslinker have been successfully synthesized. Proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy (FT-IR) were employed to characterize the resulting copolymers. The effect of EGDMA amount on the mechanical and thermal properties, swelling parameters, clarity, and oxygen permeability of the prepared xerogels and hydrogels were studied. 3 wt % of EGDMA is required to obtain clear xerogels and hydrogels. The water content (EWC), volume fraction of polymer (φ2) and weight loss during swelling decrease with increasing EGDMA content. Young’s and shear modulus (E and G) increase as EGDMA content increases, the values of E and G are 0.570–3.531 MPa and 0.217–1.359 MPa, respectively. The hydrogels were characterized in terms of modulus crosslinking density (ve and vt) and polymer-solvent interaction parameters (χ). The results are 0.220–0.613 mol/dm3 for ve, 0.105–0.441 mol/dm3 for vt, and 0.595–0.822 for χ. Thermal properties enhance by adding EGDMA whereas the oxygen permeability (P) of hydrogels decreases from 48.6 to 44.3 as water content decrease from 70.3 to 55.1.
Kopolimery zawierające 90 % mas. N-winylopirolidonu (NVP) i 10 % masmetakrylanu 3-(trimetoksysililo)propylu (TMSPM) z udziałem 0, 1, 2, 3 i 4 % mas. (w przeliczeniu na masę NVP/TMSPM) dimetakrylanu glikolu etylenowego (EGDMA) jako środka sieciującego zsyntetyzowano z wysokim stopniem konwersji. Otrzymane kopolimery charakteryzowano metodami protonowego rezonansu jądrowego (H1 NMR) i spektroskopii w podczerwieni (FT-IR). Badano wpływ udziału środka sieciującego na właściwości mechaniczne i termiczne, parametry pęcznienia, klarowność i przepuszczalność tlenu wytworzonych hydro- i kserożeli. Stwierdzono, że dodatek już 3 % mas. EGDMA wystarcza do uzyskania klarownego żelu, a w miarę zwiększania zawartości EGDMA zmniejsza się zawartość wody (EWC), ułamek objętości polimeru (φ2) oraz strata masy w procesie pęcznienia żelu NVP/TMSPM. Wartość modułu zarówno Younga (E), jak i ścinania (G) zwiększa się (E = 0,570–3,531 MPa, G = 0,217–1,359 MPa) wraz ze wzrostem udziału EGDMA w kompozycji. Wytworzone hydrożele charakteryzowano za pomocą modułów gęstości sieciowania (ve = 0,220–0,613 mol/dm3, vt = 0,105–0,441 mol/dm3) i parametru oddziaływania polimer-rozpuszczalnik (χ = 0,595–0,822). Właściwości termiczne otrzymanych hydrożeli zawierających EGDMA poprawiły się wraz ze zmniejszeniem zawartości wody (70,3–55,1), natomiast przepuszczalność tlenu się pogorszyła (P = 48,6–44,3).
Źródło:
Polimery; 2018, 63, 9; 577-585
0032-2725
Pojawia się w:
Polimery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and monomer reactivity ratios of acrylamide with 3-(trimethoxysilyl)propyl methacrylate and tris(methoxyethoxy)vinylsilane copolymers
Współczynniki reaktywności monomerów w syntezie kopolimerów akryloamidu, metakrylanu 3-(trimetoksysililo)propylu i tris(metoksyetoksy)-winylosilanu
Autorzy:
Mohammed, A. H.
Ahmad, M. B.
Ibrahim, N. A.
Zainuddin, N.
Powiązania:
https://bibliotekanauki.pl/articles/947173.pdf
Data publikacji:
2016
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
Tematy:
vinylsilane monomers
acrylamide
reactivity ratios
sequence distribution
sekwencja monomerów
Opis:
Copolymers of acrylamide (AM) with 3-(trimethoxysilyl)propyl methacrylate (TMSPMA) and tris(methoxyethoxy)vinylsilane (TMEVS) with different compositions were synthesized at low conversion by free radical polymerization in dimethylformamide (DMF) using benzoyl peroxide (BPO) as an initiator. The copolymers were characterized by Fourier transform infrared spectroscopy (FT-IR), and their thermal properties were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The copolymers composition was determined by elemental analysis. The monomer reactivity ratios were estimated by linearization methods proposed by Fineman-Ross and Kelen-Tudos, the intersection method proposed by Mayo-Lewis and nonlinear method proposed by curve fitting procedure. The derived reactivity ratios (r1, r2) are: 1.87, 0.80 for TMSPMA-co-AM and 0.22, 1.21 for TMEVS-co-AM. Both copolymers formed blocks of one of the monomer units. The microstructure of copolymers and sequence distribution of monomers in the copolymers were calculated by statistical method based on the average reactivity ratios and found that these values are in agreement with the derived reactivity ratios.
Kopolimery akryloamidu (AM) z metakrylanem 3-(trimetoksysililo)propylu (TMSPMA) itris(metoksyetoksy)winylosilanem (TMEVS), o różnych składach, zsyntetyzowano w warunkach małej konwersji metodą wolnorodnikowej polimeryzacji w dimetyloformamidzie (DMF), z zastosowaniem nadtlenku benzoilu (BPO) jako inicjatora. Otrzymane kopolimery charakteryzowano za pomocą spektroskopii w podczerwieni z transformacją Fouriera (FT-IR), różnicowej kalorymetrii skaningowej (DSC) oraz analizy termograwimetrycznej (TGA). Skład kopolimerów ustalono metodą analizy elementarnej. Współczynniki reaktywności monomerów oszacowano metodami linearyzacji zaproponowanymi przez: Finemana-Rossa, Kelena-Tudosa, Mayo-Lewisa i metodą nieliniową z zastosowaniem procedury dopasowania krzywej. Otrzymane współczynniki reaktywności (r1, r2) wynosiły: 1,87 i 0,80 dla TMSPMA-co-AM oraz 1,21 i 0,22 dla TMEVS-co-AM. Oba kopolimery miały budowę złożoną zbloków utworzonych z jednostek monomerów składowych. Mikrostrukturę oraz sekwencję monomerów w kopolimerach wyznaczono metodą statystyczną na podstawie średnich współczynników reaktywności. Stwierdzono zgodność obliczeń z wartościami otrzymanymi doświadczalnie.
Źródło:
Polimery; 2016, 61, 11-12; 758-765
0032-2725
Pojawia się w:
Polimery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heat shock increases oxidative stress to modulate growth and physico-chemical attributes in diverse maize cultivars
Autorzy:
Hussain, I.
Ashraf, M.A.
Rasheed, R.
Iqbal, M.
Ibrahim, M.
Ashraf, S.
Powiązania:
https://bibliotekanauki.pl/articles/25486.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Opis:
The present investigation was conducted to appraise the physiochemical adjustments in contrasting maize cultivars, namely, PakAfgoi (tolerant) and EV-5098 (sensitive) subjected to heat shock. Seven-day-old seedlings were exposed to heat shock for different time intervals (1, 3, 6, 24, 48 and 72 h) and data for various physiochemical attributes determined to appraise time course changes in maize. After 72 h of heat shock, the plants were grown under normal conditions for 5 d and data for different growth attributes and photosynthetic pigments recorded. Exposure to heat shock reduced growth and photosynthetic pigments in maize cultivars. The plants exposed to heat shock for up to 3 h recovered growth and photosynthetic pigments when stress was relieved. A time course rise in the relative membrane permeability, hydrogen peroxide (H2O2) and malondialdehyde contents was recorded particularly in the EV-5098 indicating that heat shock-induced oxidative stress. Activities of different enzymatic antioxidants greatly altered due to heat shock. For instance, an increase in superoxide dismutase activity was recorded in both maize cultivars. The activity of ascorbate peroxidase was greater in Pak-Afgoi. However, the peroxidase and catalase activities were higher in plants of EV-5098. Heat shock caused a significant rise in the proline and decline in the total free amino acids. Overall, the performance of Pak-Afgoi was better in terms of having lesser oxidative damage and greater cellular levels of proline. The results suggested that oxidative stress indicators (relative membrane permeability, H2O2 and malondialdehyde) and proline can be used as markers for heat shock tolerant plants.
Źródło:
International Agrophysics; 2016, 30, 4
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rain-fed plantations of the domesticated Ziziphus mauritiana in the Sahel: effects of varieties and rootstocks on yields and fruit quality
Autorzy:
Ibrahim, A.
Pasternak, D.
Guimbo, I.D.
Saidou, A.S.
Amadou, M.
Powiązania:
https://bibliotekanauki.pl/articles/2109.pdf
Data publikacji:
2015
Wydawca:
Instytut Ogrodnictwa
Tematy:
Ziziphus mauritiana
domestication
variety
rootstock
agroecology
Niger
annual rainfall
fruit yield
fruit weight
Źródło:
Journal of Horticultural Research; 2015, 23, 1
2300-5009
Pojawia się w:
Journal of Horticultural Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydrometallurgical treatment of non-sulfide zinc ore for precipitation of zinc oxide nanoparticles
Autorzy:
Abdel-Aal, E.-S. A.
Rashad, M. M.
El-Shazly, A. N.
Ibrahim, I. A.
El-Shahat, M. F.
Powiązania:
https://bibliotekanauki.pl/articles/110748.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
zinc ore
sulfuric acid leaching
filtration rate
zinc sulfate
zinc oxide nanoparticles
MB photocatalytic degradation
Opis:
Acid leaching of Egyptian zinc ore from the Um Gheig area was carried out with sulfuric acid. This study determines the optimum conditions for dissolution of non-sulfide zinc ore. The optimum conditions are 25% -74m particle size, 45 °C temperature, 2 h leaching time, 1.1 stoichiometric molar ratio of H2SO4 to Zn, 1:3 solid/liquid ratio. The maximum filtration rate is 1.6 Mg Zn•m-2•day-1at pressure difference of 0.80 bar. The zinc recovery is about 90%. As the zinc ore contains zinc silicate, some additives were tested to enhance filtration and prevent formation of silica gel. To increase the added value of the product, zinc oxide was precipitated by a co-precipitation method in a nanosize powder with average particle size ~ 20 nm. Photocatalytic degradation of methylene blue dye under UV light using ZnO nanopowders produced at different conditions was investigated. Photocatalytic efficiency with methylene blue (MB) concentration was reduced as much as 85% in 240 min with the produced nanoparticles.
Źródło:
Physicochemical Problems of Mineral Processing; 2016, 52, 2; 729-737
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Flow characteristics after installation of floating bridge in open channel
Autorzy:
Ibrahim, Mohamed M.
Eltoukhy, Mahmoud A.R.
Ghanim, Adnan D.
Powiązania:
https://bibliotekanauki.pl/articles/1844336.pdf
Data publikacji:
2021
Wydawca:
Instytut Technologiczno-Przyrodniczy
Tematy:
floating bridges
flow characteristics
flume
head loss
velocity
Opis:
A pontoon bridge, also known as a floating bridge, can be used as for pedestrian and vehicle traffic. The buoyancy of the floating bridge limits the maximum load it can carry. This research included experimental runs to study variations of open channel flow characteristics upstream and downstream a floating bridge. Eighty one runs have been carried out using a flume in a hydraulic laboratory. The experimental run program is classified into two main categories; the first investigates the velocity ratios (vds/vus) downstream and upstream the floating bridge. The second category is concerned with the energy head losses (hL) due to the presence of a floating bridge. The experimental runs are carried out using three pontoon lengths, three flow depths, six submerged depths, and three discharges. The results are analysed and graphically presented to help predict hydraulic parameters. The outcomes have shown that the floating bridge upstream, Froude number and submergence of the pontoon are the dominant parameters that affect the studied flow characteristics.
Źródło:
Journal of Water and Land Development; 2021, 49; 244-251
1429-7426
2083-4535
Pojawia się w:
Journal of Water and Land Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis, characterization and thermal polymerization of new 3,4-dihydro-2H-1,3-naphthoxazine monomers
Synteza, charakterystyka i polimeryzacja termiczna nowych monomerów 3,4-dihydro-2H-1,3-naftoksazynowych
Autorzy:
Gabbas, A. U. G.
Ahmad, M. B. H.
Zainuddin, N.
Ibrahim, N. A.
Powiązania:
https://bibliotekanauki.pl/articles/946991.pdf
Data publikacji:
2017
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
Tematy:
1,3-naphthoxazine
polynaphthoxazine
thermal polymerization
thermal properties
1,3-naftoksazyna
polinaftoksazyna
polimeryzacja termiczna
właściwości termiczne
Opis:
Two new 1,3-naphthoxazine monomers (M-A and M-B) were synthesized via a modified stepwise procedure in which methylene bromide was used for the ring-closure reaction. Condensation of 2-hydroxy-1-naphthaldehyde with 1,6-hexamethylenediamine or 1,4-phenylenediamine gives imine compounds, which were converted to 2-hydroxynaphthylamines by reduction with NaBH4 in methanol. Ring-closure reaction between the 2-hydroxynaphthylamines and methylene bromide results in the formation of 1,3-naphthoxazine monomers M-A or M-B with good yields. The structures of the synthesized monomers were confirmed using different spectroscopic techniques (including FT-IR, 1H NMR and 13C NMR), mass spectrometry, and elemental analysis. Thermal polymerization of the monomers was investigated by FT-IR and differential scanning calorimetry (DSC). Both the 1,3-naphthoxazine monomers undergo ring-opening polymerization, leading to the formation of the corresponding polynaphthoxazines [P(M-A) and P(M-B)]. The thermal stability of the polynaphthoxazines was thereafter studied by thermogravimetric analysis (TGA).
Za pomocą zmodyfikowanej trójetapowej syntezy, w której do reakcji zamknięcia pierścienia zastosowano bromek metylenu, otrzymano dwa nowe monomery 1,3-naftoksazyny (M-A i M-B). Kondensacja 2-hydroksy-1-naftaldehydu z 1,6-heksametylenodiaminą lub 1,4-fenylenodiaminą pozwala na wytworzenie związków iminowych, które następnie przez redukcję NaBH4 w metanolu są przekształcane w 2-hydroksynaftylaminy. Reakcja zamknięcia pierścienia pomiędzy 2-hydroksynaftylaminą i bromkiem metylenu prowadzi do utworzenia z dobrymi wydajnościami monomerów 1,3-naftoksazyny M-A i M-B. Struktury zsyntetyzowanych monomerów potwierdzono stosując różne techniki spektroskopowe, spektroskopię masową oraz analizę elementarną. Polimeryzację termiczną monomerów badano za pomącą spektroskopii w podczerwieni z transformatą Fouriera (FT-IR) i różnicowej kalorymetrii skaningowej (DSC). Oba monomery 1,3-naftoksazyny uległy polimeryzacji z otwarciem pierścienia dając odpowiednie polinaftoksazyny [P(M-A) i P(M-B)]. Za pomocą analizy termograwimetrycznej (TGA) zbadano stabilność termiczną otrzymanych polinaftoksazyn.
Źródło:
Polimery; 2017, 62, 2; 86-92
0032-2725
Pojawia się w:
Polimery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Framework of performance measurement practices within construction companies in Egypt
Autorzy:
Dziekoński, K.
Ibrahim, O. H. M. F.
Mahamadu, A.-M.
Manu, P.
Powiązania:
https://bibliotekanauki.pl/articles/125609.pdf
Data publikacji:
2018
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
performance
measurement system
construction
industry
Egypt
wydajność
system miar
budowa
przemysł
Egipt
Opis:
The construction industry is considered as one of the most important sectors in Egypt. One of the major challenges faced by the industry, however, is the unavailability of suitable performance measurement systems for assessing companies’ performance. Modern performance assessment systems adopt a more universal approach to the measurement of construction company performance as opposed to the traditional project triangle. This paper aims to examine the practice of performance measurement in the Egyptian construction industry. Results show dominant role of in-house developed performance management systems as well as the use of KPIs as a method of performance assessment. The study further reveals that the highest importance is given to measures related to the time of project delivery, quality of works, clients’ satisfaction and profitability. Hence, the traditional project triangle of project’s success is the most prevalent approach to performance evaluation in the construction industry in Egypt. However, a shift towards a more holistic approach to performance assessment in larger companies was observed.
Źródło:
Engineering Management in Production and Services; 2018, 10, 2; 7-14
2543-6597
2543-912X
Pojawia się w:
Engineering Management in Production and Services
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The cotton mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) as a new insect pest on tomato plants in Egypt
Autorzy:
Ibrahim, S.S.
Moharum, F.A.
Abd El-Ghany, N.M.
Powiązania:
https://bibliotekanauki.pl/articles/65060.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
Recently, the mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) was recorded as a new pest on tomato plants (Lycopersicon esculentum Mill) growing in Egypt. The mealybugs specimens were collected from tomato plants in the Qalyoubia governorate during summer season of 2014. The mealybug was identified as P. solenopsis based on the morphological characters and taxonomic key of this species. This study represents the first record of P. solenopsis as a new insect pest attacking tomato plants in Egypt.
Źródło:
Journal of Plant Protection Research; 2015, 55, 1
1427-4345
Pojawia się w:
Journal of Plant Protection Research
Dostawca treści:
Biblioteka Nauki
Artykuł
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