| 1. |
- Haris, Abdullah, et al.
(författare)
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Prolonged Repellent Activity of Plant Essential Oils against Dengue Vector, Aedes aegypti
- 2023
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Ingår i: Molecules. - : MDPI AG. - 1431-5157 .- 1420-3049. ; 28:3
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Tidskriftsartikel (refereegranskat)abstract
- Repellents are effective personal protective means against outdoor biting mosquitoes. Repellent formulations composed of EOs are finding increased popularity among consumers. In this study, after an initial screening of 11 essential oils (EOs) at the concentration of 33 μg/cm2, five of the most repellent EOs, Perovskia atriplicifolia, Citrus reticulata (fruit peels), C. reticulata (leaves), Mentha longifolia, and Dysphania ambrosioides were further investigated for repellent activity against Aedes aegypti mosquitoes in time span bioassays. When tested at the concentrations of 33 μg/cm2, 165 μg/cm2 and 330 μg/cm2, the EO of P. atriplicifolia showed the longest repellent effect up to 75, 90 and 135 min, respectively, which was followed by C. reticulata (peels) for 60, 90 and 120 min, M. longifolia for 45, 60 and 90 min, and C. reticulata (leaves) for 30, 45 and 75 min. Notably, the EO of P. atriplicifolia tested at the dose of 330 μg/cm2 showed complete protection for 60 min which was similar to the commercial mosquito repellent DEET. Gas chromatographic-mass spectrometric analyses of the EOs revealed camphor (19.7%), limonene (92.7%), sabinene (24.9%), carvone (82.6%), and trans-ascaridole (38.8%) as the major constituents of P. atriplicifolia, C. reticulata (peels), C. reticulata (leaves), M. longifolia, and D. ambrosioides, respectively. The results of the present study could help develop plant-based commercial repellents to protect humans from dengue mosquitoes.
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| 2. |
- Parveen, Amna, et al.
(författare)
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Chemical composition of essential oils from natural populations of Artemisia scoparia collected at different altitudes : antibacterial, mosquito repellent, and larvicidal effects
- 2024
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Ingår i: Molecules. - 1431-5157 .- 1420-3049. ; 29:6, s. 1359-
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Tidskriftsartikel (refereegranskat)abstract
- The current study aimed to evaluate the presence of chemical variations in essential oils (EOs) extracted from Artemisia scoparia growing at different altitudes and to reveal their antibacterial, mosquito larvicidal, and repellent activity. The gas chromatographic–mass spectrometric analysis of A. scoparia EOs revealed that the major compounds were capillene (9.6–31.8%), methyleugenol (0.2–26.6%), β-myrcene (1.9–21.4%), γ-terpinene (1.5–19.4%), trans-β-caryophyllene (0.8–12.4%), and eugenol (0.1–9.1%). The EO of A. scoparia collected from the city of Attock at low elevation was the most active against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa bacteria (minimum inhibitory concentration of 156–1250 µg/mL) and showed the best mosquito larvicidal activity (LC50, 55.3 mg/L). The EOs of A. scoparia collected from the high-altitude areas of Abbottabad and Swat were the most repellent for females of Ae. aegypti and exhibited repellency for 120 min and 165 min, respectively. The results of the study reveal that different climatic conditions and altitudes have significant effects on the chemical compositions and the biological activity of essential oils extracted from the same species.
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| 3. |
- Ullah, Muhammad Kaleem, et al.
(författare)
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Tri-doped ceria (M0.2Ce0.8O2-δ, M= Sm0.1 Ca0.05 Gd0.05) electrolyte for hydrogen and ethanol-based fuel cells
- 2019
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388. ; 773, s. 548-554
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Tidskriftsartikel (refereegranskat)abstract
- In recent scientific research, an interest has been gained significantly by rare earth metals such as cerium (Ce), samarium (Sm) and gadolinium (Gd) due to their use in fuel cells as electrolyte and catalysts. When used in an electrolyte, these materials lower the fuel cell's operating temperature compared to a conventional electrolyte, for example, yittria-stabilized zirconia (YSZ) which operates at a high temperature (≥800 °C). In this paper, the tri-doped ceria, M0.2Ce0.8O2-δ(M = Sm0.1Ca0.05Gd0.05) electrolyte powders was synthesized using the co-precipitation method at 80 °C. These dopants were used for CeO2with a total molar ratio of 1 M. Dry-pressed powder technique was used to make fuel cell pellets from the powder and placed them in the furnace to sinter at 700 °C for 60 min. Electrical conductivity of such a pellet in air was 1.2 × 10−2S cm−1at 700 °C measured by the ProboStat-NorECs setup. The crystal structure was determined with the help of X-ray diffraction (XRD), which showed that all the dopants were successfully doped in CeO2. Raman spectroscopy and UV-VIS spectroscopy were also carried out to analyse the molecular vibrations and absorbance, respectively. The maximum open-circuit voltages (OCVs) for hydrogen and ethanol fuelled at 550 °C were observed to be 0.89 V and 0.71 V with power densities 314 mW cm−2and 52.8 mW cm−2, respectively.
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| 4. |
- Abbas, Muhammad Ghazanfar, et al.
(författare)
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Chemical Composition, Larvicidal and Repellent Activities of Wild Plant Essential Oils against Aedes aegypti
- 2023
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Ingår i: Biology. - : MDPI AG. - 2079-7737. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Bio-degradable and eco-friendly essential oils (EOs) extracted from Mentha longifolia, Salsola imbricata, Erigeron bonariensis, E. canadensis, Ailanthus altissima, and Zanthoxylum armatum were investigated for their repellent and larvicidal potential against Aedes aegypti mosquitoes. The EOs of M. longifolia, S. imbricata, E. bonariensis, E. canadensis, A. altissima, and Z. armatum exhibited 99.0%, 96.8%, 40.2%, 41.7%, 29.1%, and 13.2% repellency against mosquitoes at a tested dose of 33.3 μg/cm2, respectively. In time span bioassays, the EOs of M. longifolia, S. imbricata, E. bonariensis, and E. canadensis showed more than 40% repellency for 60 min at a tested dose of 330 μg/cm2. Larvicidal bioassays revealed that larvae of Ae. aegypti were the most susceptible to M. longifolia (LC50, 39.3 mg/L), E. bonariensis (LC50, 26.0 mg/L), E. canadensis (LC50, 35.7 mg/L), and Z. armatum (LC50, 35.9 mg/L) EOs upon 48 h exposure. The most abundant constituents in the EOs of M. longifolia, S. imbricata, E. bonariensis, E. canadensis and A. altissima were piperitone oxide (45.5%), carvone (39.9%), matricaria ester (43.1%), (31.7%) and eugenol (24.4%), respectively. Our study demonstrates that EOs of M. longifolia, S. imbricata, E. bonariensis, and E. canadensis might be used to control Ae. aegypti mosquitoes without harming humans or the environment.
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| 5. |
- Abbas, Ghazanfar, et al.
(författare)
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Electrochemical investigation of mixed metal oxide nanocomposite electrode for low temperature solid oxide fuel cell
- 2017
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Ingår i: International Journal of Modern Physics B. - : WORLD SCIENTIFIC PUBL CO PTE LTD. - 0217-9792. ; 31:27
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Tidskriftsartikel (refereegranskat)abstract
- Zinc-based nanostructured nickel (Ni) free metal oxide electrode material Zn-0.60/CU0.20Mn0.20 oxide (CMZO) was synthesized by solid state reaction and investigated for low temperature solid oxide fuel cell (LTSOFC) applications. The crystal structure and surface morphology of the synthesized electrode material were examined by XRD and SEM techniques respectively. The particle size of ZnO phase estimated by Scherer's equation was 31.50 nm. The maximum electrical conductivity was found to be 12.567 S/cm and 5.846 S/cm in hydrogen and air atmosphere, respectively at 600 degrees C. The activation energy of the CMZO material was also calculated from the DC conductivity data using Arrhenius plots and it was found to be 0.060 and 0.075 eV in hydrogen and air atmosphere, respectively. The CMZO electrode-based fuel cell was tested using carbonated samarium doped ceria composite (NSDC) electrolyte. The three layers 13 mm in diameter and 1 mm thickness of the symmetric fuel cell were fabricated by dry pressing. The maximum power density of 728.86 mW/cm(2) was measured at 550 degrees C.
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| 6. |
- Rafique, Asia, et al.
(författare)
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Multioxide phase-based nanocomposite electrolyte (M@SDC where M = Zn2+ / Ba2+/ La2+/Zr-2/Al3+) materials
- 2020
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Ingår i: Ceramics International. - : ELSEVIER SCI LTD. - 0272-8842 .- 1873-3956. ; 46:52, s. 6882-6888
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with the development of a highly dense and stable electrolyte on the base of nanoionics oxide interface theory. This gives a comparative study of two-phase nanocomposite electrolytes that are developed for low temperature solid oxide fuel cells (LT-SOFCs). These nanocomposites are synthesised with different oxides, which are coated on the doped ceria that showed high oxide ion mobility for LT-SOFCs. These novel two-phase nanocomposite oxide ionic conductors (MCe0.8Sm0.2O2-MO2, where M = Zn2+/Ba2+/La3+/Zr2+/Al3+) were synthesised by a co-precipitation method. The interface study between these two phases was analysed by electrochemical impedance spectroscopy (EIS), while ionic conductivities were measured with DC conductivity (four probe method). The nanocomposite electrolytes exhibited higher conductivities with the increase of concentration of coated oxides but decreased at a certain level. The structural or morphological properties of the nanocomposite electrolytes were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The thermal stability was investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The maximum performance of 590 mW/cm(2) at 550 degrees C was obtained for the Zn@SDC based cell, and the rest of the coated samples Ba@SDC, La@SDC, Zr@SDC and Al@SDC based cells showed values of 550 mW/cm(2), 540 mW/cm(2), 450 mW/cm(2), 340 mW/cm(2), respectively, with hydrogen as a fuel. Therefore, the coated-SDC based nanocomposite materials are a good approach for lowering the operating temperature to achieve the challenges of the solid oxide fuel cells (SOFC). These two-phase nanocomposite electrolytes satisfy the all requirements which one electrolyte should have, like high ionic conduction, thermodynamic stability and negligible electronic conduction.
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| 7. |
- Raza, Rizwan, et al.
(författare)
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Electrochemical study of the composite electrolyte based on samaria-doped ceria and containing yttria as a second phase
- 2011
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Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738 .- 1872-7689. ; 188:1, s. 58-63
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study is to develop new oxide ionic conductors based on nanocomposite materials for an advanced fuel cell (NANOCOFC) approach. The novel two phase nanocomposite oxide ionic conductors, Ce0.8Sm0.2O2-delta (SDC)-Y2O3 were synthesized by a co-precipitation method. The structure and morphology of the prepared electrolyte were investigated by means of X-ray diffraction (XRD) and high resolution scanning electron microscopy (HRSEM). XRD results showed a two phase composite consisting of yttrium oxide and samaria doped ceria and SEM results exhibited a nanostructure form of the sample. The yttrium oxide was used on the SDC as a second phase. The interface between two constituent phases and the ionic conductivities were studied with electrochemical impedance spectroscopy (EIS). An electrochemical study showed high oxide ion mobility and conductivity of the Y2O3-SDC two phase nanocomposite electrolytes at a low temperature (300-600 degrees C). Maximum conductivity (about 1.0 S cm(-1)) was obtained for the optimized Y2O3-SDC composite electrolyte at 600 degrees C. It is found that the nanocomposite electrolytes show higher conductivities with the increased concentration of yttrium oxides but decreases after reaching a certain level. A high fuel cell performance, 0.75 W cm(-2), was achieved at 580 degrees C.
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