| 1. |
- Ullah, Kaleem, et al.
(författare)
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Expanding the living liver donor pool in countries having limited deceased donor activity : Pakistani perspective
- 2022
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Ingår i: Transplant Immunology. - : Elsevier. - 0966-3274 .- 1878-5492. ; 75
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Tidskriftsartikel (refereegranskat)abstract
- Over the last decades, liver transplantation (LT) has evolved into a life-saving procedure. Due to limited deceased donor activities in the eastern world, living donor liver transplantation (LDLT) had flourished tremendously in most Asian countries. Yet, these LDLT activities fall short of meeting the expected demands. Pakistan, a developing country, bears a major burden of liver diseases. Currently, only few centers offer LDLT services in the country. On the other hand, deceased donor liver transplantation (DDLT) activities have not started due to social, cultural, and religious beliefs. Various strategies can be adopted successfully to overcome the scarcity of live liver donors (LLDs) and to expand the donor pool, keeping in view donor safety and recipient outcome. These include consideration of LLDs with underlying clinical conditions like G6PD deficiency and Hepatitis B core positivity. Extended donor criteria can also be utilized and relaxation can be made in various donors' parameters including upper age and body mass index after approval from the multidisciplinary board. Also, left lobe grafts, grafts with various anatomical variations, and a low graft-to-recipient ratio can be considered in appropriate situations. ABO-incompatible LT and donor swapping at times may help in expanding the LLDs pool. Similarly, legislation is needed to allow live non-blood-related donors for organ donations. Finally, community education and awareness through various social media flat forms are needed to promote deceased organ donation.
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| 2. |
- Ali, Amjad, et al.
(författare)
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A potential electrolyte (Ce1-x CaxO2-delta) for fuel cells:Theoretical andexperimental study
- 2018
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Ingår i: Ceramics International. - : ELSEVIER SCI LTD. - 0272-8842 .- 1873-3956. ; 44:11, s. 12676-12683
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Tidskriftsartikel (refereegranskat)abstract
- First-principles calculations are performed using density function theory to explore the effects of dopant Ca in ceria (Ce1-x CaxO2-delta). The impact of oxygen vacancy on band gap and density of states is examined in doped ceria using generalized gradient approximations. Vacancy association and vacancy formation energies of the doped ceria are calculated to reveal the effect of dopant on ion conduction. The experimental study of the sample Ce0.875Ca0.125O2-delta) was performed to compare with the theoretical results. The obtained results from theoretical calculation and experimental techniques show that oxygen vacancy increases the volume, lattice constant (5.47315 angstrom) but decrease the band gap (1.72 eV) and bulk modulus. The dopant radius (1.173 angstrom) and lattice constant (5.4718 angstrom) are also calculated by equations which is close to the DFT lattice parameter. The result shows that oxygen vacancy shifts the density of states to lower energy region. Band gap is decreased due to shifting of valence states to conduction band. Vacancy formation shows a significance increase in density of states near the Fermi level. Density of states at Fermi level is proportional to the conductivity, so an increase in density of states near the Fermi level increases the conductivity. The experimental measured ionic conductivity is found to 0.095 S cm(-1) at 600 degrees C. The microstructural studies is also reported in this work.
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| 3. |
- Ali, A., et al.
(författare)
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Alkaline earth metal and samarium co-doped ceria as efficient electrolytes
- 2018
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 112:4
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Tidskriftsartikel (refereegranskat)abstract
- Co-doped ceramic electrolytes M0.1Sm0.1Ce0.8O2-δ (M = Ba, Ca, Mg, and Sr) were synthesized via co-precipitation. The focus of this study was to highlight the effects of alkaline earth metals in doped ceria on the microstructure, densification, conductivity, and performance. The ionic conductivity comparisons of prepared electrolytes in the air atmosphere were studied. It has been observed that Ca0.1Sm0.1Ce0.8O2-δ shows the highest conductivity of 0.124 Scm-1 at 650 °C and a lower activation energy of 0.48 eV. The cell shows a maximum power density of 630 mW cm-2 at 650 °C using hydrogen fuel. The enhancement in conductivity and performance was due to increasing the oxygen vacancies in the ceria lattice with the increasing dopant concentration. The bandgap was calculated from UV-Vis data, which shows a red shift when compared with pure ceria. The average crystallite size is in the range of 37-49 nm. DFT was used to analyze the co-doping structure, and the calculated lattice parameter was compared with the experimental lattice parameter.
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| 4. |
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| 5. |
- Ali, Amjad, et al.
(författare)
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Electrochemical study of composite materials for coal-based direct carbon fuel cell
- 2018
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Ingår i: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 43:28, s. 12900-12908
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Tidskriftsartikel (refereegranskat)abstract
- The efficient conversion of solid carbon fuels into energy by reducing the emission of harmful gases is important for clean environment. In this regards, direct carbon fuel cell (DCFC) is a system that converts solid carbon directly into electrical energy with high thermodynamic efficiency (100%), system efficiency of 80% and half emission of gases compared to conventional coal power plants. This can generate electricity from any carbonaceous fuel such as charcoal, carbon black, carbon fiber, graphite, lignite, bituminous coal and waste materials. In this paper, ternary carbonate-samarium doped ceria (LNK-SDC) electrolyte has been synthesized via co-precipitation technique, while LiNi-CuZnFeO (LNCZFO) electrode has been prepared using solid state reaction method. Due to significant ionic conductivity of electrolyte LNK-SDC, it is used in DCFC. Three types of solid carbon (lignite, bituminous, sub-bituminous) are used as fuel to generate power. The X-ray diffraction confirmed the cubic crystalline structure of samarium doped ceria, whereas XRD pattern of LNCZFO showed its composite structure. The proximate and ultimate coal analysis showed that fuel (carbon) with higher carbon content and lower ash content was promising fuel for DCFC. The measured ionic conductivity of LNK-SDC is 0.0998 Scm(-1) and electronic conductivity of LNCZFO is 10.1 Scm(-1) at 700 degrees C, respectively. A maximum power density of 58 mWcm(-2) is obtained using sub bituminous fuel.
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| 6. |
- Ali, Amjad, et al.
(författare)
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Promising electrochemical study of titanate based anodes in direct carbon fuel cell using walnut and almond shells biochar fuel
- 2019
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Ingår i: Journal of Power Sources. - : ELSEVIER. - 0378-7753 .- 1873-2755. ; 434
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Tidskriftsartikel (refereegranskat)abstract
- The direct carbon fuel cell (DCFC) is an efficient device that converts the carbon fuel directly into electricity with 100% theoretical efficiency contrary to practical efficiency around 60%. In this paper four perovskite anode materials La0.4Sr0.6M0.09Ti0.91O3-delta (M = Ni, Fe, Co, Zn) have been prepared using sol-gel technique to measure the performance of the device using solid fuel. These materials have shown reasonable stability and conductivity at 700 degrees C. Further structural analysis of as-prepared anode material using XRD technique reveals a single cubic perovskite structure with average crystallite size roughly 47 nm. Walnut and almond shells biochar have also been examined as a fuel in DCFC at the temperature range 400-700 degrees C. In addition, Elemental analysis of walnut and almond shells has shown high carbon content and low nitrogen and sulfur contents in the obtained biochar. Subsequently, the superior stability of as-prepared anode materials is evident by thermogravimetric analysis in pure N-2 gas atmosphere. Conversely, the LSFT anode has shown the highest electronic conductivity of 7.53Scm(-1) at 700 degrees C. The obtained power density for LSFTO3-delta composite anode mixed in sub-bituminous coal, walnut and almond shells biochar is of 68, 55, 48 mWcm(-2) respectively. A significant improvement in performance of DCFC (78 mWcm(-2)) was achieved.
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| 7. |
- Irshad, Muneeb, et al.
(författare)
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A Brief Description of High Temperature Solid Oxide Fuel Cell's Operation, Materials, Design, Fabrication Technologies and Performance
- 2016
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Ingår i: Applied Sciences. - : MDPI AG. - 2076-3417. ; 6:3
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Forskningsöversikt (refereegranskat)abstract
- Today's world needs highly efficient systems that can fulfill the growing demand for energy. One of the promising solutions is the fuel cell. Solid oxide fuel cell (SOFC) is considered by many developed countries as an alternative solution of energy in near future. A lot of efforts have been made during last decade to make it commercial by reducing its cost and increasing its durability. Different materials, designs and fabrication technologies have been developed and tested to make it more cost effective and stable. This article is focused on the advancements made in the field of high temperature SOFC. High temperature SOFC does not need any precious catalyst for its operation, unlike in other types of fuel cell. Different conventional and innovative materials have been discussed along with properties and effects on the performance of SOFC's components (electrolyte anode, cathode, interconnect and sealing materials). Advancements made in the field of cell and stack design are also explored along with hurdles coming in their fabrication and performance. This article also gives an overview of methods required for the fabrication of different components of SOFC. The flexibility of SOFC in terms fuel has also been discussed. Performance of the SOFC with varying combination of electrolyte, anode, cathode and fuel is also described in this article.
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| 8. |
- Rafique, Asia, et al.
(författare)
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Significance enhancement in the conductivity of core shell nanocomposite electrolytes
- 2015
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 5:105, s. 86322-86329
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Tidskriftsartikel (refereegranskat)abstract
- Today, there is great demand of electrolytes with high ionic conductivities at low operating temperatures for solid-oxide fuel cells. Therefore, a co-doped technique was used to synthesize a highly ionically conductive two phase nanocomposite electrolyte Sr/Sm-ceria-carbonate by a co-precipitation method. A significant increase in conductivity was measured in this co-doped Sr/Sm-ceria-carbonate electrolyte at 550 degrees C as compared to the more commonly studied samarium doped ceria. The fuel cell power density was 900 mW cm(-2) at low temperature (400-580 degrees C). The composite electrolyte was found to have homogenous morphology with a core-shell structure using SEM and TEM. The two phase core-shell structure was confirmed using XRD analysis. The crystallite size was found to be 30-60 nm and is in good agreement with the SEM analysis. The thermal analysis was determined with DSC. The enhancement in conductivity is due to two effects; co-doping of Sr in samarium doped ceria and it's composite with carbonate which is responsible for the core-shell structure. This co-doped approach with the second phase gives promise in addressing the challenge to lower the operating temperature of solid oxide fuel cells (SOFC).
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| 9. |
- Ullah, Kaleem, et al.
(författare)
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Cerebral phaeohyphomycosis in liver transplant recipient : A case report
- 2022
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Ingår i: Clinical Case Reports. - : Wiley. - 2050-0904. ; 10:12
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Tidskriftsartikel (refereegranskat)abstract
- Cerebral phaeohyphomycosis is a fungal brain infection with a high fatality rate. It is caused by dematiaceous fungi and is increasingly recognized as a cause of serious illness in both immunocompetent and immunocompromised patients. We report cerebral phaeohyphomycosis in a liver transplant recipient. He was treated with multiple surgeries and antifungals and made a complete recovery. This report highlights that early and aggressive surgical intervention and extended antifungal coverage can have a positive outcome even in immunocompromised patients. The fungal infection in immunocompromised patients should be considered and treated aggressively.
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| 10. |
- Ullah, Kaleem, et al.
(författare)
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Evaluation of Handover Activities from the Perspective of the System Acquisition and Front-End Support
- 2010
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Ingår i: Computer Sciences and Convergence Information Technology (ICCIT), 2010 5th International Conference on. - : IEEE Computer Society Digital Library. - 9781424485673 - 9788988678305 ; , s. 326-332
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Konferensbidrag (refereegranskat)abstract
- Even if software handover is a critical process in the lifecycle of a software system, there is still very little research done within its domain. In this paper, we evaluate the taxonomy of handover activities as defined in EM3: Handover Process Model. We do it in an industrial setting in a context where a software system is handed over from a vendor conducting system development, evolution and maintenance to an acquirer using the system and conducting front-end support. Our results show that the taxonomy is realistic in the context studied. However, it misses some important deployment and training activities.
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| 11. |
- Ullah, Kaleem, et al.
(författare)
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Walking a Software Handover Process
- 2010
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Konferensbidrag (refereegranskat)abstract
- To assure that process models correctly mirror the industrial reality, they need to be extracted and evaluated in many different contexts. In this paper, we walk a handover process in a Pakistani company, called VAST Pakistanusing the EM3 taxonomy of activities as a roadmap. We walk the process by following VAST Pakistan’s software lifecycle phases and by placing EM3 activities on them. The context studied covers handover of a software system from the vendor conducting system development, evolution and maintenance to an acquirer organization being the end-user and front-end support provider. The study is made from the acquirer’s perspective. Our results show that the EM3 taxonomy of activities covers correct handover activities. Due to its specific context, however, the process studied did not utilize all the activities as defined in EM3. Their choice is strongly dependent on the handover process context under study.
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| 12. |
- 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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