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    Wyświetlanie 1-15 z 15
    Tytuł:
    Mycoremediation of Heavy Metals Contaminated Soil by Using Indigenous Metallotolerant Fungi
    Autorzy:
    Akram, Muhammad Bilal
    Khan, Ibrar
    Ur Rehman, Mujaddad
    Sarwar, Abid
    Ullah, Najeeb
    ur Rahman, Shafiq
    Aziz, Tariq
    Alharbi, Metab
    Alshammari, Abdulrahman
    Alasmari, Abdullah F.
    Powiązania:
    https://bibliotekanauki.pl/articles/27315654.pdf
    Data publikacji:
    2023
    Wydawca:
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
    Tematy:
    Mycoremediation
    Heavy Metals Contaminated Soil
    Korangi Industrial Estate
    FTIR
    Fourier Transform Infrared Spectroscopy
    SEM
    Scanning Electron Microscope
    Opis:
    The present study was aimed to identify the indigenous fungal strains which could possibly be applied to the bioremediation of heavy metal-contaminated soil. The contaminated soil samples of Korangi Industrial Estate Karachi were found to have total concentration of Cu 1.044 mgL1 , and Pb 0.631 mgL–1. A total of eight indigenous strains of the fungus were isolated and screened for bioremediation capacity from heavy metals-contaminated soil. For the bioremediation of Lead (Pb) these same indigenous eight fungal strains were used for biological remediation. All the fungal isolated with enhanced bioremediation capability were through phenotypic and genotypical characterization. The topology of the phylograms established that the fungal isolates used in this study were allocated to: K1 (Penicillium notatum), K2 (Aspergillus parasiticus), K3 (Aspergillus fumigatus), K4 (Aspergillus flavus), K5 (Aspergillus terries), K6 (Fusarium solani), K7 (Penicillium chrysogenum), K8 (Aspergillus niger), K9 (Penicillium piceum) and K10 (Penicillium restrictum). Thus, K8 fungal isolate was found to be more efficient with maximum bioremediation capacity, for copper and lead removal efficiency, and selected for FTIR and SEM to find out the uptake of Cu and Pb which of the functional groups are involved, and further to detect the effects of bioleaching of both heavy metals on to the surface of K8 fungus biomass. The current study indicates that indigenous fungal isolates could be used with high potency to remediate or clean up the heavy metals-contaminated soil either by the technique of in situ or ex-situ bioremediation.
    Źródło:
    Polish Journal of Chemical Technology; 2023, 25, 3; 1--13
    1509-8117
    1899-4741
    Pojawia się w:
    Polish Journal of Chemical Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study of Zeolite Phase Made from Rice Husk Ash and Sidrap Clay
    Autorzy:
    Armayani, M.
    Mansur, Musdalifa
    Asra, Reza
    Irwan, Muh
    Ramadhanty, Dhian
    Subaer, Subaer
    Abdullah, Mohd Mustafa Al Bakri
    Aziz, Ikmal Hakem A.
    Jeż, Bartłomiej
    Nabiałek, Marcin
    Powiązania:
    https://bibliotekanauki.pl/articles/2203746.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    autoclave
    clay
    rice husk ash
    zeolite
    Opis:
    Zeolite has been successfully synthesized from clay and rice husk ash in the form of powder by using the hydrothermal method with variations in chemical compositions of alkaline solution and the amount of rice husk ash. The clay raw material was obtained from the Sidrap area of South Sulawesi and rice husk ash is obtained from the burning pile of rice husks. Sidrap clay and rice husk ash were activated using an alkaline solution of NaOH and varied rice husk ash and the addition of AlCl3. The addition of AlCl3, an alkaline solution of NaOH and H2O was used in the amount of 25.5 grams and variations of rice husk ash were 2.5 grams and 6.5 grams. Meanwhile, without the addition of AlCl3, an alkaline solution of NaOH and H2O was used for 20.5 grams and variations of rice husk ash from 2.5 grams and 6.5 grams. Then the mixture was then put into an autoclave with a temperature of 100°C for 3 hours. The basic material used in the manufacture of zeolite is carried out by X-ray Fluorescence (XRF) characterization to determine the constituent elements of basic material, which showed the content of SiO2 was 45.80 wt% in the clay and 93.40% in the rice husk ash. The crystalline structure of the zeolite formed was characterized by X-Ray Diffraction (XRD). It was found the resulting zeolite were identified as Zeolite-Y, Hydrosodalite, and ZSM-5. The microstructure properties of the resulting zeolite were determined by using Scanning Electron Microscopy (SEM).
    Źródło:
    Archives of Metallurgy and Materials; 2023, 68, 1; 269--274
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sustained Release of Drug Facilitated Through Chemically Crosslinked Polyvinyl Alcohol-Gelatin (PVA-GE) Hydrogels. A sustainable biomedical approach
    Autorzy:
    Ali, Shaukat
    Ranjha, Nazar Muhammad
    Ahmad, Bashir
    Khan, Ayaz Ali
    Hassan, Fakhr Ul
    Aziz, Tariq
    Alharb, Metab
    Alshammari, Abdulrahman
    Alasmari, Abdullah F.
    Alharbi, Mousa Esa
    Powiązania:
    https://bibliotekanauki.pl/articles/27315648.pdf
    Data publikacji:
    2023
    Wydawca:
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
    Tematy:
    hydrogel
    gelatin
    drug release
    ciprofloxacin HCl
    polyvinyl alcohol
    Opis:
    The present study aimed to prepare hydrogel based on polyvinyl alcohol (PVA) and gelatin (Ge) and characterization of PVA/Ge hydrogel for their potential use as a sustained drug delivery system. Polyvinyl Alcohol (PVA) and-Gelatin (Ge) were cross-linked using glutaraldehyde (GA) as a crosslinking agent and hydrochloric acid (HCl) as a catalyst. Different feed polymer ratio and crosslinking agent concentration were used to prepare a series of PVA/Ge hydrogels. The obtained PVA/Ge hydrogels were investigated for dynamic and equilibrium swelling studies. The effect of polymers ratio, degree of crosslinking and pH of the medium on swelling of PVA/Ge hydrogels was investigated. Furthermore, the values of diffusion coeficient (D), volume fraction, polymer-solvent interaction parameter, molecular weight between crosslink and crosslink density were calculated. For swelling studies, 0.05M USP phosphate buffer solutions of different pH (1.2, 5.5, 6.5 and 7.5) were used. For the drug release study, ciprofloxacin HCl was loaded into selected samples as a model drug. The release of drug from these samples was performed for 12 hours in USP phosphate buffers of pH 1.2, 5.5 and 7.5. The release data from these samples were fitted into various kinetic models like zero order, first order, Higuchi and Peppas models to investigate the release mechanism. It was found that by varying the composition of PVA/Ge hydrogel and GA concentration, a significant difference was observed in drug release kinetics. FTIR spectroscopy and X-ray diffraction were used for the characterization of hydrogels. PVA/Ge hydrogel showed sustained release of the model drug at various pH values suggesting its potential use as a sustained drug delivery system.
    Źródło:
    Polish Journal of Chemical Technology; 2023, 25, 2; 56--65
    1509-8117
    1899-4741
    Pojawia się w:
    Polish Journal of Chemical Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Synthesis of silver nanoparticles by aqueous extract of Zingiber officinale and their antibacterial activities against selected species
    Autorzy:
    Hussain, Zawar
    Jahangeer, Muhammad
    ur Rahman, Shafiq
    Ihsan, Tamanna
    Sarwar, Abid
    Ullah, Najeeb
    Aziz, Tariq
    Alharbi, Metab
    Alshammari, Abdulrahman
    Alasmari, Abdullah F.
    Powiązania:
    https://bibliotekanauki.pl/articles/27315653.pdf
    Data publikacji:
    2023
    Wydawca:
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
    Tematy:
    Nanotechnology
    Antibacterial activity
    Silver-nanoparticles
    green synthesis
    Ginger
    Opis:
    Silver nanoparticles have special plasmonic and antibacterial characteristics that make them efficient in a variety of commercial medical applications. According to recent research, chemically synthesized silver nanoparticles are harmful even in low concentrations. It was crucial to identify appropriate synthesis methods that may have low costs and be nontoxic to the environment. Zingiber officinale (ginger) extracts used to prepare silver nanoparticles were inexpensive and environmentally friendly, and the best physicochemical characteristics were analyzed. Silver nanoparticles were characterized by using UV-visible spectroscopy, Scanning electron microscopy (SEM), and X-ray diffraction (XRD). The surface Plasmon resonance peak at 425 nm was observed using UV-Visible spectroscopy. Scanning electron microscopy observed that the nanoparticles were spherical and ranged in size from 5 to 35 nm. The XRD pattern values of 2θ: 38.2° , 46.3° , and 64.58° are used to determine the planes (111), (200), and (220). The silver nanoparticle’s existence was verified by the face-centered cubic (FCC). Silver nanoparticles were found to have antibacterial efficacy against gram-positive Staphylococcus and gram-negative bacteria such as Pseudomonas aeruginosa, Klebsiella Aerogenes, Salmonella, Staphylococcus and Escherichia coli. The antibacterial activity of silver nanoparticles was observed using the agar well diffusion (AWD) method at three different concentrations (100 μg/ ml, 75 μg/ml, and 50 μg/ml). The zone of inhibition measured against the bacterial strains pseudomonas Aeruginosa, Klebsiella aerogenes, Escherichia coli, Salmonella and Staphylococcus which were (18.4±1.25 mm, 16.9±0.74 mm, 14.8±1.25 mm), (16.8±0.96 mm, 14.6±0.76 mm, 14.0±1.15 mm), (19.7±0.76 mm, 18.2±0.66 mm, 15.4±1.15 mm), (16.6±0.67 mm, 14.2±0.23 mm, 12.8±0.78 mm) and (12±0.68 mm, 10±0.20 mm, 08±0.15 mm). These nanoparticles’ potent antibacterial properties may enable them to be employed as nanomedicines for a variety of gramnegative bacterial illness treatments.
    Źródło:
    Polish Journal of Chemical Technology; 2023, 25, 3; 23--30
    1509-8117
    1899-4741
    Pojawia się w:
    Polish Journal of Chemical Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Assessment of Geopolymer Concrete for Underwater Concreting Properties
    Autorzy:
    Zaidi, Fakhryna Hannanee Ahmad
    Ahmad, Romisuhani
    Al Bakri Abdullah, Mohd Mustafa
    Wan Ibrahim, Wan Mastura
    Aziz, Ikmal Hakem
    Junaidi, Subaer
    Luhar, Salmabanu
    Powiązania:
    https://bibliotekanauki.pl/articles/2106595.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    geopolymer
    underwater concrete
    fly ash
    kaolin
    Opis:
    For ages, concrete has been used to construct underwater structures. Concrete laying underwater is a very complex procedure important to the success or failure of underwater projects. This paper elucidates the influence of alkali activator ratios on geopolymers for underwater concreting; focusing on the geopolymer concrete synthesized from fly ash and kaolin activated using sodium hydroxide and sodium silicate solutions. The geopolymer mixtures were designed to incorporate multiple alkali activator ratios to evaluate their effects on the resulting geopolymers’ properties. The fresh concrete was molded into 50 mm cubes in seawater using the tremie method and tested for its engineering properties at 7 and 28 days (curing). The control geopolymer and underwater geopolymers’ mechanical properties, such as compressive strength, water absorption density, and setting time were also determined. The differences between the control geopolymer and underwater geopolymer were determined using phase analysis and functional group analysis. The results show that the geopolymer samples were optimally strengthened at a 2.5 alkali activator ratio, and the mechanical properties of the control geopolymer exceeded that of the underwater geopolymer. However, the underwater geopolymer was determined to be suitable for use as underwater concreting material as it retains 70% strength of the control geopolymer.
    Źródło:
    Archives of Metallurgy and Materials; 2022, 67, 2; 677--684
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of Naoh Molar Concentration on Microstructure and Compressive Strength of Dolomite/Fly Ash-Based Geopolymers
    Autorzy:
    Azimi, Emy Aizat
    Salleh, Mohd M. A. A.
    Abdullah, Mohd Mustafa Al Bakri
    Aziz, Ikmal Hakem A.
    Hussin, Kamarudin
    Chaiprapa, Jitrin
    Vizureanu, Petrica
    Yoriya, Sorachon
    Nabiałek, Marcin
    Wyslocki, Jerzy J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2125545.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    dolomite/fly ash
    geopolymer
    NaOH concentration
    synchrotron
    micro-XRF
    Opis:
    Dolomite can be used as a source of aluminosilicate to produce geopolymers; however, this approach is limited by its low reactivity. This study analyzes the viability of producing geopolymers using dolomite/fly-ash with sodium silicate and NaOH solutions (at multiple concentrations) by determining the resultant geopolymers’ compressive strengths. The dolomite/fly-ash-based geopolymers at a NaOH concentration of ~22 M resulted in an optimum compressive strength of 46.38 MPa after being cured for 28 days, and the SEM and FTIR analyses confirmed the denser surface of the geopolymer matrix. The synchrotron micro-XRF analyses confirmed that the Ca concentration exceeded that of Si and Mg, leading to the formation of calcium silicate hydrate, which strengthens the resulting geopolymers.
    Źródło:
    Archives of Metallurgy and Materials; 2022, 67, 3; 993--998
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Finite Element Analysis on Structural Behaviour of Geopolymer Reinforced Concrete Beam using Johnson-Cook Damage in ABAQUS
    Autorzy:
    Mortar, Nurul Aida Mohd
    Al Bakri Abdullah, Mohd Mustafa
    Hussin, Kamarudin
    Razak, Rafiza Abdul
    Hamat, Sanusi
    Hilmi, Ahmad Humaizi
    Shahedan, Noorfifi Natasha
    Li, Long Yuan
    Aziz, Ikmal Hakem A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2174588.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    fly ash geopolymer
    geopolymer concrete
    finite element analysis
    Johnson Cook Damage
    ABAQUS software
    Opis:
    This paper details a finite element analysis of the behaviour of Si-Al geopolymer concrete beam reinforced steel bar under an impulsive load and hyper velocity speed up to 1 km/s created by an air blast explosion. The initial torsion stiffness and ultimate torsion strength of the beam increased with increasing compressive strength and decreasing stirrup ratio. The study involves building a finite element model to detail the stress distribution and compute the level of damage, displacement, and cracks development on the geopolymer concrete reinforcement beam. This was done in ABAQUS, where a computational model of the finite element was used to determine the elasticity, plasticity, concrete tension damages, concrete damage plasticity, and the viability of the Johnson-Cook Damage method on the Si-Al geopolymer concrete. The results from the numerical simulation show that an increase in the load magnitude at the midspan of the beam leads to a percentage increase in the ultimate damage of the reinforced geopolymer beams failing in shear plastic deformation. The correlation between the numerical and experimental blasting results confirmed that the damage pattern accurately predicts the response of the steel reinforcement Si-Al geopolymer concrete beams, concluded that decreasing the scaled distance from 0.298 kg/m3 to 0.149 kg/m3 increased the deformation percentage.
    Źródło:
    Archives of Metallurgy and Materials; 2022, 67, 4; 1349--1354
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Setting Time and after Setting Properties of High Calcium Fly Ash Geopolymers with Different Concentration of Sodium Hydroxide
    Autorzy:
    Mohamed, Rosnita
    Razak, Rafiza Abd
    Abdullah, Mohd Mustafa Al Bakri
    Sofri, Liyana Ahmad
    Aziz, Ikmal Hakem
    Shahedan, Noor Fifinatasha
    Powiązania:
    https://bibliotekanauki.pl/articles/2106582.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    high calcium fly ash geopolymers
    setting time
    heat evolved
    early age properties
    concentration of sodium hydroxide
    Opis:
    Setting time in geopolymers is known as the time taken for the transition phase of liquid to solid of the geopolymer system in which is represented in the initial setting and final setting. Setting time is significant specifically for application in the construction field. This study intends to determine the setting time of high calcium fly ash geopolymers and the properties of the geopolymers after setting (1-day age). This includes the determination of heat evolved throughout geopolymerization using Differential Scanning Calorimeter. After setting properties determination includes compressive strength and morphology analysis at 1-day age. High calcium fly ash was used as geopolymer precursor. Meanwhile, for mixing design, the alkali activator was a mixture of sodium silicate and sodium hydroxide (concentration varied from 6M-14M) with a ratio of 2.5 and a solid-to-liquid ratio of 2.5. From this study, it was found that high calcium fly ash geopolymer with 12M of NaOH has a reasonable setting time which is suitable for on-site application as well as an optimal heat evolved (-212 J/g) which leads to the highest compressive strength at 1-day age and no formation of microcracks observed on the morphology. Beyond 12M, too much heat evolved in the geopolymer system can cause micro-cracks formation thus lowering the compressive strength at 1-day age.
    Źródło:
    Archives of Metallurgy and Materials; 2022, 67, 2; 563--567
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Silica Bonding Reaction on Fly Ash Based Geopolymer Repair Material System with Incorporation of Various Concrete Substrates
    Autorzy:
    Al Bakri Abdullah, Mohd Mustafa
    Aziz, Ikmal Hakem A.
    Zailani, Warid Wazien Ahmad
    Rahim, Shayfull Zamree Abd
    Yong, Heah Cheng
    Sandu, Andrei Victor
    Peng, Loke Siu
    Powiązania:
    https://bibliotekanauki.pl/articles/2174557.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    fly ash geopolymer
    repair material
    concrete substrate
    interfacial zone transition
    Opis:
    This paper presents an experimental investigation on the mechanical properties and microstructure of geopolymer repair materials mixed using fly ash (FA) and concrete substrates. An optimal combination of FA and concrete substrate was determined using the compressive test of geopolymer mortar mixed with various concrete substrate classes. It was found that the contribution of (C35/45) concrete substrates with the FA geopolymer mortar increases the 28-day bonding strength by 25.74 MPa. The microstructure analysis of the samples using scanning electron microscopy showed the denser structure owing to the availability of high calcium and iron elements distribution. These metal cations (Ca2+ and Fe3+) are available at OPC concrete substrate as a result from the hydration process reacted with alumina-silica sources of FA and formed calcium aluminate silicate hydrate (C-A-S-H) gels and Fe-bonding linkages.
    Źródło:
    Archives of Metallurgy and Materials; 2022, 67, 4; 1277--1281
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Investigation of Ground Granulated Blast Furnace Slag Geopolymer at High Temperature by Using Electron Backscatter Diffraction Analysis
    Autorzy:
    Aziz, Ikmal Hakem
    Mohd Mustafa Al Bakri, Abdullah
    Salleh, Mohd Arif Anuar Mohd
    Yoriya, Sorachon
    Rafiza, Abd Razak
    Mohamed, Rosnita
    Baltatu, Madalina Simona
    Powiązania:
    https://bibliotekanauki.pl/articles/2048835.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    geopolymer
    ground granulated blast furnace slag
    electron backscatter diffraction
    Opis:
    This paper elucidated the potential of electron backscatter diffraction analysis for ground granulated blast furnace slag geopolymers at 1000°C heating temperature. The specimen was prepared through the mechanical ground with sandpaper and diamond pad before polished with diamond suspension. By using advanced technique electron backscatter diffraction, the microstructure analysis and elemental distribution were mapped. The details on the crystalline minerals, including gehlenite, mayenite, tobermorite and calcite were easily traced. Moreover, the experimental Kikuchi diffraction patterns were utilized to generate a self-consistent reference for the electron backscatter diffraction pattern matching. From the electron backscatter diffraction, the locally varying crystal orientation in slag geopolymers sample of monoclinic crystal observed in hedenbergite, orthorhombic crystal in tobermorite and hexagonal crystal in calcite at 1000°C heating temperature.
    Źródło:
    Archives of Metallurgy and Materials; 2022, 67, 1; 227-231
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermal Insulation and Mechanical Properties in the Presence of Glas Bubble in Fly Ash Geopolymer Paste
    Autorzy:
    Shahedan, Noor Fifinatasha
    Abdullah, Mohd Mustafa Al Bakri
    Mahmed, Norsuria
    Liew, Yun Ming
    Shayfull, Zamree Abd Rahim
    Aziz, Ikmal Hakem A.
    Kadir, Aeslina Abdul
    Sandu, Andrei Victor
    Ghazali, Mohd Fathullah
    Powiązania:
    https://bibliotekanauki.pl/articles/2048833.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    glass bubble
    thermal insulation
    geopolymers
    fly ash
    Opis:
    The density, compressive strength, and thermal insulation properties of fly ash geopolymer paste are reported. Novel insulation material of glass bubble was used as a replacement of fly ash binder to significantly enhance the mechanical and thermal properties compared to the geopolymer paste. The results showed that the density and compressive strength of 50% glass bubble was 1.45 g/cm3 and 42.5 MPa, respectively, meeting the standard requirement for structural concrete. Meanwhile, the compatibility of 50% glass bubbles tested showed that the thermal conductivity (0.898 W/mK), specific heat (2.141 MJ/m3 K), and thermal diffusivity (0.572 mm2 /s) in meeting the same requirement. The improvement of thermal insulation properties revealed the potential use of glass bubbles as an insulation material in construction material.
    Źródło:
    Archives of Metallurgy and Materials; 2022, 67, 1; 221-226
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental investigation of chopped steel wool fiber at various ratio reinforced cementitious composite panels
    Autorzy:
    Rmdan Amer, Akrm A.
    Al Bakri Abdullah, Mohd Mustafa
    Ming, Liew Yun
    Aziz, Ikmal Hakem A.
    Mohd Tahir, Muhammad Faheem
    Abd Rahim, Shayfull Zamree
    Amer, Hetham A. R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1852332.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    włókno stalowe
    włókno posiekane
    wełna stalowa
    kompozyt cementowy
    płyta kompozytowa
    nośność
    steel fiber
    chopped fiber
    steel wool
    cementitious composite
    composite panel
    load carrying capacity
    Opis:
    The flexural toughness of chopped steel wool fiber reinforced cementitious composite panels was investigated. Reinforced cementitious composite panels were produced by mixing of chopped steel wool fiber with a ratio range between 0.5% to 6.0% and 0.5% as a step increment of the total mixture weight, where the cement to sand ratio was 1:1.5 with water to cement ratio of 0.45. The generated reinforced cementitious panels were tested at 28 days in terms of load-carrying capacity, deflection capacities, post-yielding effects, and flexural toughness. The inclusion of chopped steel wool fiber until 4.5% resulted in gradually increasing load-carrying capacity and deflection capacities while, provides various ductility, which would simultaneously the varying of deflection capability in the post-yielding stage. Meanwhile, additional fiber beyond 4.5% resulted in decreased maximum load-carrying capacity and increase stiffness at the expense of ductility. Lastly, the inclusion of curves gradually.
    Źródło:
    Archives of Civil Engineering; 2021, 67, 3; 661-671
    1230-2945
    Pojawia się w:
    Archives of Civil Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of non-equidistant baffle spacing in a small shell and tube heat exchanger
    Autorzy:
    Aziz, Abdullah
    Rehman, Shafique
    Powiązania:
    https://bibliotekanauki.pl/articles/240423.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    thermal distribution
    baffle spacing
    heat exchanger
    turbulence modeling
    CFD study
    Opis:
    Most of the formulations regarding the characteristics of a shell and tube heat exchanger have a common assumption; namely that the baffle plates are equidistant. This assumption fails to cater the real world scenario for defective baffles as the alteration in a shell and tube heat exchanger invalidates the equidistant baffle spacing of the plates. In this regard, a small six baffles heat exchanger was modeled in the computational fluid dynamics software package and studied by removing each baffle plate one at a time. Effect of removing each baffle plate on the temperature, pressure, heat transfer coefficient, and total heat transfer rate was recorded. It was observed that variation in the pressure drop for the same number of baffle plates varies along the axial order of the plates. The change in pressure drop due to the removal of the baffle plate near the inlet and the outlet was lowest and reaches a maximum in the axial center. It was also found that the plates below the radial center contribute higher towards the overall heat transfer as compared to those above.
    Źródło:
    Archives of Thermodynamics; 2020, 41, 2; 201-221
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Does Self-esteem Mediate the Relationship between Gratitude and Subjective Well-being?
    Autorzy:
    Yildirim, Murat
    Alshehri, Nouf Abdullah
    Aziz, Izaddin Ahmad
    Powiązania:
    https://bibliotekanauki.pl/articles/2129720.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    subjective well-being
    gratitude
    self-esteem
    satisfaction with life
    positive experience
    negative experience
    Opis:
    There is a growing body of research investigating the relationships among gratitude, self-esteem, and subjective well-being. However, there remains a scarcity of research examining the impact of self-esteem on the relationship between gratitude and subjective well-being within Arabic context. In this study, 300 Arabic speaking adults completed measurements of gratitude, self-esteem, satisfaction with life, and positive and negative experiences. Participants’ ages ranged between 18 and 54 years with a mean age of 29.67 years (SD = 8.91). The correlation results revealed that there were significant positive relationships between gratitude, self-esteem, satisfaction with life, and positive experience, while there were significant negative relationships between gratitude, self-esteem, satisfaction with life, and negative experience. The results also showed that gratitude and self-esteem directly predicted subjective well-being. Additionally, using structural equation modeling, self-esteem exerted a mediation effect on the relationship between gratitude and subjective well-being. The results suggest that enhancing self-esteem could assist adults who have gratitude to experience greater subjective well-being. Using the source of self-esteem, researchers and professionals could improve one’s subjective well-being by employing various gratitude activities.
    Źródło:
    Polish Psychological Bulletin; 2019, 50, 2; 149-156
    0079-2993
    Pojawia się w:
    Polish Psychological Bulletin
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fixed point theorems for monotone mappings in ordered Banach spaces under weak topology features
    Autorzy:
    Alahmari, Abdullah
    Mabrouk, Mohamed
    Taoudi, Mohamed-Aziz
    Powiązania:
    https://bibliotekanauki.pl/articles/357719.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Rzeszowska im. Ignacego Łukasiewicza. Oficyna Wydawnicza
    Tematy:
    fixed point theorem
    order cone
    increasing operator
    decreasing operator
    weakly condensing
    measure of weak noncompactness
    twierdzenie o punkcie stałym
    stożek
    operator
    miara słabej niezgodności
    Opis:
    We present several fixed point theorems for monotone nonlinear operators in ordered Banach spaces. The main assumptions of our results are formulated in terms of the weak topology. As an application, we study the existence of solutions to a class of first-order vectorvalued ordinary differential equations. Our conclusions generalize many well-known results.
    Źródło:
    Journal of Mathematics and Applications; 2019, 42; 5-19
    1733-6775
    2300-9926
    Pojawia się w:
    Journal of Mathematics and Applications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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