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- Amin, M. A., et al.
(författare)
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Synthesis of Cyano-Benzylidene Xanthene Synthons Using a Diprotic Brønsted Acid Catalyst, and Their Application as Efficient Inhibitors of Aluminum Corrosion in Alkaline Solutions
- 2022
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Ingår i: Molecules. - : MDPI AG. - 1420-3049. ; 27:17
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Tidskriftsartikel (refereegranskat)abstract
- Novel cyano-benzylidene xanthene derivatives were synthesized using one-pot and condensation reactions. A diprotic Brønsted acid (i.e., oxalic acid) was used as an effective catalyst for the promotion of the synthesis process of the new starting xanthene–aldehyde compound. Different xanthene concentrations (ca. 0.1–2.0 mM) were applied as corrosion inhibitors to control the alkaline uniform corrosion of aluminum. Measurements were conducted in 1.0 M NaOH solution using Tafel extrapolation and linear polarization resistance (LPR) methods. The investigated xanthenes acted as mixed-type inhibitors that primarily affect the anodic process. Their inhibition efficiency values were enhanced with inhibitor concentration, and varied according to their chemical structures. At a concentration of 2.0 mM, the best-performing studied xanthene derivative recorded maximum inhibition efficiency values of 98.9% (calculated via the Tafel extrapolation method) and 98.4% (estimated via the LPR method). Scanning electron microscopy (SEM) was used to examine the morphology of the corroded and inhibited aluminum surfaces, revealing strong inhibitory action of each studied compound. High-resolution X-ray photoelectron spectroscopy (XPS) profiles validated the inhibitor compounds’ adsorption on the Al surface. Density functional theory (DFT) and Monte Carlo simulations were applied to investigate the distinction of the anticorrosive behavior among the studied xanthenes toward the Al (111) surface. The non-planarity of xanthenes and the presence of the nitrile group were the key players in the adsorption process. A match between the experimental and theoretical findings was evidenced. © 2022 by the authors.
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- Mersal, G. A. M., et al.
(författare)
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Study of half metallic ferromagnetism and thermoelectric properties of spinel chalcogenides BaCr2X4 (X 1/4 S, Se, Te) for spintronic and energy harvesting
- 2022
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Ingår i: Journal of Materials Research and Technology-Jmr&T. - : Elsevier BV. - 2238-7854. ; 18:May–June 2022, s. 2831-2841
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Tidskriftsartikel (refereegranskat)abstract
- The control of spin degree of freedom in electronics open new horizons to manipulate, transfer, and storage data at fasters speed. For this the structural, electronic, and magnetic characteristics of BaCr2X4 (X 1/4 S, Se, Te) spinels are addressed comprehensively. The more energy release in ferromagnetic states than antiferromagnetic states, and formation energy verified thermal stability in FM states. The Curie temperature, and spin polarization density have been reported for room temperature ferromagnetism. The detail and nature of ferromagnetism have illustrated by band structures, density of states, hybridization, double exchange mechanism, crystal field energy, exchange energies and exchange constants. The transfer of magnetic moment from Cr sites to other nonmagnetic sites (Ba, X)
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- Aidas, Kestutis, et al.
(författare)
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The Dalton quantum chemistry program system
- 2014
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Ingår i: WIREs Computational Molecular Science. - : Wiley. - 1759-0876 .- 1759-0884. ; 4:3, s. 269-284
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Tidskriftsartikel (refereegranskat)abstract
- Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree-Fock, Kohn-Sham, multiconfigurational self-consistent-field, MOller-Plesset, configuration-interaction, and coupled-cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic-structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge-origin-invariant manner. Frequency-dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one-, two-, and three-photon processes. Environmental effects may be included using various dielectric-medium and quantum-mechanics/molecular-mechanics models. Large molecules may be studied using linear-scaling and massively parallel algorithms. Dalton is distributed at no cost from for a number of UNIX platforms.
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| 10. |
- Amin, Mohammed A., et al.
(författare)
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Elemental Variability of PM2.5 Aerosols in Historical and Modern Areas of Jeddah, Saudi Arabia
- 2022
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Ingår i: Atmosphere. - : MDPI AG. - 2073-4433. ; 13:12
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Tidskriftsartikel (refereegranskat)abstract
- Air particulate matter with a diameter of 2.5 µm (PM2.5) were assembled for a whole year from the historical Jeddah district. Additional PM2.5 aerosols were collected during the autumn and winter seasons from another newly constructed district in Jeddah city (Alnaeem). The annual concentration of the total mass of the PM2.5 aerosols from the historical Jeddah site was found to be 43 ± 6 µg/m3. In addition, the average of the total mass concentration at the Alnaeem site was 61 ± 14 µg/m3. These values were greater than the annual mass concentration of the air quality standards of the European Commission (25 µg/m3) and the World Health Organization (10 µg/m3). The elemental analysis of the collected fine atmospheric aerosols was achieved by energy dispersive X-ray fluorescence (EDXRF) with three secondary targets (CaF2, Ge, and Mo). Quantitative elemental analyses of twenty-two (22) elements were achieved starting from the low atomic number element (Na) up to the high atomic number element (Pb). Although the historical Jeddah site is not well organized, the elemental concentrations and total mass concentrations were lower than those of the other site. The statistical analyses including enrichment factors, correlation analysis, and the principal component analysis revealed more information about the source identification of the PM2.5 aerosols collected from both locations. It was recognized that the elements Al, Si, K, Ca, Ti, Mn, Fe, Rb, and Sr originated from a natural source. On the other hand, the elements Ta, Br, Pb, Sc, Ni, Cu, Zn, and S originated from anthropogenic sources. Finally, the elements Na, Cl, and Br came mainly from the sea spray source.
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| 11. |
- Amin, Mohammed A., et al.
(författare)
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Non-Covalent Functionalization of Graphene Oxide-Supported 2-Picolyamine-Based Zinc(II) Complexes as Novel Electrocatalysts for Hydrogen Production
- 2022
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Ingår i: Catalysts. - : MDPI AG. - 2073-4344. ; 12:4
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Tidskriftsartikel (refereegranskat)abstract
- Three mononuclear 2-picolylamine-containing zinc(III) complexes viz [(2-PA)2ZnCl]2(ZnCl4)] (Zn1), [(2-PA)2Zn(H2O)](NO3)2] (Zn2) and [Zn(2-PA)2(OH)]NO3] (Zn3) were synthesized and fully characterized. Spectral and X-ray structural characteristics showed that the Zn1 complex has a square-pyramidal coordination environment around a zinc(II) core. The hydroxide complex Zn3 was non-covalently functionalized with few layers of graphene oxide (GO) sheets, formed by exfoliation of GO in water. The resulting Zn3/GO hybrid material was characterized by FT-IR, TGA-DSC, SEM-EDX and X-ray powder diffraction. The way of interaction of Zn3 with GO has been established through density functional theory (DFT) calculations. Both experimental and theoretical findings indicate that, on the surface of GO, the complex Zn3 forms a complete double-sided adsorption layer. Zn3 and its hybrid form Zn3/GO have been individually investigated as electrocatalysts for the hydrogen evolution reaction. The hybrid heterogenized form Zn3/GO was supported on glassy carbon (GC) with variable loading densities of Zn3 (0.2, 0.4 and 0.8 mg cm−2) to form electrodes. These electrodes have been tested as molecular electrocatalysts for the hydrogen evolution reaction (HER) using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) in 0.1 M KOH. Results showed that both GC-Zn3 and GC-Zn3/GO catalysts for the HER are highly active, and with increase of the catalyst’s loading density, this catalytic activity enhances. The high catalytic activity of HER with a low onset potential of −140 mV vs. RHE and a high exchange current density of 0.22 mA cm−2 is achieved with the highest loading density of Zn3 (0.8 mg cm−2). To achieve a current density of 10 mA cm−2, an overpotential of 240 mV was needed.
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| 15. |
- Badawi, Ali, et al.
(författare)
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Exploring the structural and optical properties of FeS filled graphene/PVA blend for environmental-friendly applications
- 2021
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Ingår i: Journal of Polymer Research. - : Springer Science and Business Media LLC. - 1022-9760 .- 1572-8935. ; 28
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the role of iron sulfide (FeS) content on the structural and optical properties of graphene/polyvinyl alcohol (Gr/PVA) blend has been examined for environmental-friendly applications. Gr/PVA blend filled with FeS (0 to 10 wt%) were equipped using the casting technique. The prepared samples were studied via a scanning electron microscope, X-ray diffractometer, FT-IR and UV–visible-NIR spectrophotometers. XRD analysis shows that the crystallinity increases with increasing FeS concentration in the host Gr/PVA blend. UV–visible-NIR analysis shows that the direct optical bandgap of composite blends shrinks from 5.37 to 4.68eV as FeS content is increased to 10 wt%. Also, it confirms that the refractive index and optical conductivity of Gr/PVA blend could be significantly enhanced via FeS filling. FeS filled Gr/PVA blends are recommended eco-friendly applications.
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| 16. |
- Bläckberg, Lisa, et al.
(författare)
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Investigations of surface coatings to reduce memory effect in plastic scintillator detectors used for radioxenon detection
- 2011
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 656:1, s. 84-91
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Tidskriftsartikel (refereegranskat)abstract
- In this work Al(2)O(3) and SiO(2) coatings are tested as Xe diffusion barriers on plastic scintillator substrates. The motivation is improved beta-gamma coincidence detection systems, used to measure atmospheric radioxenon within the verification regime of the Comprehensive Nuclear-Test-Ban Treaty. One major drawback with the current setup of these systems is that the radioxenon tends to diffuse into the plastic scintillator material responsible for the beta detection, resulting in an unwanted memory effect. Here, coatings with thicknesses between 20 and 900 nm have been deposited onto plastic scintillators, and investigated using two different experimental techniques. The results show that all tested coatings reduce the Xe diffusion into the plastic. The reduction is observed to increase with coating thickness for both coating materials. The 425 nm Al(2)O(3) coating is the most successful one, presenting a diffusion reduction of a factor 100, compared to uncoated plastic. In terms of memory effect reduction this coating is thus a viable solution to the problem in question.
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| 19. |
- M Del Campo, J, et al.
(författare)
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Phase II randomized study of trabectedin given as two different every 3 weeks dose schedules (1.5 mg/m(2) 24 h or 1.3 mg/m(2) 3 h) to patients with relapsed, platinum-sensitive, advanced ovarian cancer
- 2009
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Ingår i: ANNALS OF ONCOLOGY. - : Elsevier BV. - 0923-7534. ; 20:11, s. 1794-802
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Tidskriftsartikel (refereegranskat)abstract
- Patients and methods: Patients previously treated with less than two or two previous chemotherapy lines were randomized to receive trabectedin 1.5 mg/m(2) 24 h (arm A, n = 54) or 1.3 mg/m(2) 3 h (arm B, n = 53). Objective response rate (ORR) per RECIST was the primary efficacy end point. Toxic effects were graded according to the National Cancer Institute-Common Toxicity Criteria v. 2.0. Results: ORR was 38.9% [95% confidence interval (CI) 25.9% to 53.1%; arm A] and 35.8% (95% CI 23.1% to 50.2%; arm B) (intention-to-treat primary analysis). Median time to progression was 6.2 months (95% CI 5.3-8.6 months; arm A) and 6.8 months (95% CI 4.6-7.4 months; arm B). Frequent severe adverse events were nausea/vomiting (24%, arm A; 15%, arm B) and fatigue (15%, arm A; 10%, arm B). Common severe laboratory abnormalities were transient, noncumulative neutropenia (55%, arm A; 37%, arm B) and transaminase increases (alanine aminotransferase, 55%, arm A; 59%, arm B). Conclusions: Both every-3-weeks trabectedin regimes, 1.5 mg/m(2) 24 h and 1.3 mg/m(2) 3 h, were active and reasonably well tolerated in AOC platinum-sensitive patients. Trabectedin every-3-weeks has promising activity and deserves to be further evaluated in relapsed AOC.
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| 20. |
- Shaltout, Abdallah A., et al.
(författare)
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Elemental Composition of PM2.5 Aerosol in a Residential–Industrial Area of a Mediterranean Megacity
- 2020
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Ingår i: Archives of Environmental Contamination and Toxicology. - : Springer Science and Business Media LLC. - 0090-4341 .- 1432-0703. ; 78, s. 68-78
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Tidskriftsartikel (refereegranskat)abstract
- Very little is known about the elemental composition and possible sources of fine aerosol particles from Mediterranean megacities. Fine aerosol particles were collected at a residential-industrial area in Greater Cairo, Egypt, during the period from October 2010 to May 2011. The elemental compositions of the collected samples were quantified by using a homemade energy dispersive x-ray fluorescence spectrometer, whereas black carbon was quantified by a black smoke detector. Fifteen elements have been quantified. Of these constituents, Ca, C, Cl, S, and Fe had the highest concentrations: greater than 1µgm−3. The overall mean mass concentration of the collected samples equals 70µgm−3; this value exceeds the European Union annual Air Quality Standard levels. The individual elemental concentrations of the fine particles were found to be dominated by elements linked to mineral dust. Most of the monthly variations of elemental concentrations can be attributed to seasonal meteorological conditions. Other possible sources were vehicle-exhaust and industrial activities. The results pinpoint the problem of identifying different sources when one source, in this case, the nearby deserts, is dominant. The results from this study contribute to the growing knowledge of concentrations, composition, and possible sources of ambient fine particulate matter. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.
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- Boman, I L, et al.
(författare)
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Using electronic aids to daily living after acquired brain injury : a study of the learning process and the usability.
- 2007
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Ingår i: Disability and Rehabilitation. - : Informa UK Limited. - 1748-3107 .- 1748-3115. ; 2:1, s. 23-33
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The purpose was to study the ability of persons with memory impairments after acquired brain injury to learn how to and use electronic aids to daily living (EADL) and to describe changes in function and quality of life. METHOD: Eight participants stayed in two apartments equipped with a set of basic and advanced EADL for either 4 or 6 months during an intervention time of 2 years. The teaching and learning method was influenced by certain principles of errorless learning. Ability to learn to use EADL was measured by structured observations. Function and quality of life were assessed with self-rating questionnaires. RESULTS: Results indicate that the participants learned to use EADL in their everyday activities. They perceived that EADL were very useful and easy to learn. Occupational performance and satisfaction with occupational performance and quality of life was improved. CONCLUSION: The results indicate that EADL may play an important role in facilitating everyday activities and improve satisfaction with occupational performance and quality of life for people with memory impairments. The study indicates the importance of adjusting technology to the user's needs and calls for more consideration for human-technology interaction factors.
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