The design of the flow field is highly responsible for the performance of the Proton Exchange Membrane Fuel Cell (PEMFC). In this study, pin type flow channel is numerically analyzed by arranging carbon made porous ma...The design of the flow field is highly responsible for the performance of the Proton Exchange Membrane Fuel Cell (PEMFC). In this study, pin type flow channel is numerically analyzed by arranging carbon made porous material in uniform and zigzag manner on the rib surface of the flow field. The study focuses on enhancing the performance of PEMFC by reducing liquid flooding in the interface between the rib and Gas Diffusion Layer (GDL). A single PEMFC having an active area of 25 cm2, with three flow channel designs (conventional serpentine, pin type flow channel with 2 mm cubical porous inserts in zigzag and uniform pattern) are modeled for the numerical analysis. The effect of porosity of the carbon inserts on the cell performance is studied by varying its value from 0.6 to 0.9. The results show that the performance of the flow channel with zigzag and uniformly positioned porous inserts is more than the conventional serpentine flow channel by 20.36% and 16.87% respectively. The reason for this increase is the removal of the accumulated water from the rib surface due to the capillary action of the porous carbon inserts. This helps in eliminating the stagnant water regions under the rib and thereby helps in reducing liquid flooding.展开更多
An inverse spinel-type metal oxide, magnesium-manganese-titanium oxide （Mg2Mn0.5Ti0.5O4）, were prepared using the coprecipitation/thermal crystallization method. The extraction/insertion reaction with this material ...An inverse spinel-type metal oxide, magnesium-manganese-titanium oxide （Mg2Mn0.5Ti0.5O4）, were prepared using the coprecipitation/thermal crystallization method. The extraction/insertion reaction with this material was investigated by X-ray, saturation capacity of exchange, pH titration, and distribution coefficient （Kd） measurement. The acid treatments of Mg2Mn0.5Ti0.5O4 caused Mg^2＋ extractions of more than 81%, whereas the dissolutions of Mn^4＋ and Ti^4＋ were less than 10%. The experimental results proved that the acid-treated sample has a capacity of exchange 56 mg·g^-1 for Li^＋ in the solution. The chemical analysis showed that the Li^＋ extraction/insertion progressed mainly by ion-exchange mechanism and surface adsorption.展开更多
Objective: Diabetic kidney disease DKD (Diabetic nephropathy DN) is considered one of the chronic micro vascular complications of diabetes mellitus and considered the commonest cause leading to chronic renal failure a...Objective: Diabetic kidney disease DKD (Diabetic nephropathy DN) is considered one of the chronic micro vascular complications of diabetes mellitus and considered the commonest cause leading to chronic renal failure and chronic renal dialysis. Genetic susceptibility has been implicated in DKD. The angiotensin converting enzyme (ACE) is one of the key roles in the renin angiotensin system cascade by converting angiotensin I to angiotensin II which plays a key role in regulation of blood pressure as well as electrolytes and fluid balance. This study addressed the association of (ACE) gene polymorphisms with DN in Egyptian (T2DM) patients. Methods: Our research comprised of 75 cases of T2DM with diabetic kidney disease, 100 cases of T2DM without DKD and 94 healthy volunteers. Different genotypes of ACE gene were determined by SSP-PCR analysis. Results: Gene polymorphism of ACE (DD, ID, II) in diabetic patient with DKD is 44%, 52%, 4% respectively and for T2DM individuals without DKD is 23%, 72%, 5% respectively. (DD) had significant higher frequencies in T2DM patients with DKD compared to those without DKD (p < 0.005) and (ID) had significant higher frequencies in T2DM without DKD (p < 0.0001). These results indicated that there is an association between ACE gene polymorphisms and susceptibility of diabetic patients to be affected by diabetic kidney disease. Conclusion: From our results, we can conclude that genotype of ACE in Egypt DD is the genotype of cases diabetic kidney disease. So the presence of D allele has a significant relation with diabetic kidney disease. Our data confirm the role of ACE in its relationship with diabetic kidney disease in Egyptian type 2 diabetic patients.展开更多
文摘The design of the flow field is highly responsible for the performance of the Proton Exchange Membrane Fuel Cell (PEMFC). In this study, pin type flow channel is numerically analyzed by arranging carbon made porous material in uniform and zigzag manner on the rib surface of the flow field. The study focuses on enhancing the performance of PEMFC by reducing liquid flooding in the interface between the rib and Gas Diffusion Layer (GDL). A single PEMFC having an active area of 25 cm2, with three flow channel designs (conventional serpentine, pin type flow channel with 2 mm cubical porous inserts in zigzag and uniform pattern) are modeled for the numerical analysis. The effect of porosity of the carbon inserts on the cell performance is studied by varying its value from 0.6 to 0.9. The results show that the performance of the flow channel with zigzag and uniformly positioned porous inserts is more than the conventional serpentine flow channel by 20.36% and 16.87% respectively. The reason for this increase is the removal of the accumulated water from the rib surface due to the capillary action of the porous carbon inserts. This helps in eliminating the stagnant water regions under the rib and thereby helps in reducing liquid flooding.
文摘An inverse spinel-type metal oxide, magnesium-manganese-titanium oxide （Mg2Mn0.5Ti0.5O4）, were prepared using the coprecipitation/thermal crystallization method. The extraction/insertion reaction with this material was investigated by X-ray, saturation capacity of exchange, pH titration, and distribution coefficient （Kd） measurement. The acid treatments of Mg2Mn0.5Ti0.5O4 caused Mg^2＋ extractions of more than 81%, whereas the dissolutions of Mn^4＋ and Ti^4＋ were less than 10%. The experimental results proved that the acid-treated sample has a capacity of exchange 56 mg·g^-1 for Li^＋ in the solution. The chemical analysis showed that the Li^＋ extraction/insertion progressed mainly by ion-exchange mechanism and surface adsorption.
文摘Objective: Diabetic kidney disease DKD (Diabetic nephropathy DN) is considered one of the chronic micro vascular complications of diabetes mellitus and considered the commonest cause leading to chronic renal failure and chronic renal dialysis. Genetic susceptibility has been implicated in DKD. The angiotensin converting enzyme (ACE) is one of the key roles in the renin angiotensin system cascade by converting angiotensin I to angiotensin II which plays a key role in regulation of blood pressure as well as electrolytes and fluid balance. This study addressed the association of (ACE) gene polymorphisms with DN in Egyptian (T2DM) patients. Methods: Our research comprised of 75 cases of T2DM with diabetic kidney disease, 100 cases of T2DM without DKD and 94 healthy volunteers. Different genotypes of ACE gene were determined by SSP-PCR analysis. Results: Gene polymorphism of ACE (DD, ID, II) in diabetic patient with DKD is 44%, 52%, 4% respectively and for T2DM individuals without DKD is 23%, 72%, 5% respectively. (DD) had significant higher frequencies in T2DM patients with DKD compared to those without DKD (p < 0.005) and (ID) had significant higher frequencies in T2DM without DKD (p < 0.0001). These results indicated that there is an association between ACE gene polymorphisms and susceptibility of diabetic patients to be affected by diabetic kidney disease. Conclusion: From our results, we can conclude that genotype of ACE in Egypt DD is the genotype of cases diabetic kidney disease. So the presence of D allele has a significant relation with diabetic kidney disease. Our data confirm the role of ACE in its relationship with diabetic kidney disease in Egyptian type 2 diabetic patients.
