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Effect of Tm3+ on the Strong Magnetic Anisotropy in the High-Tc Superconductor TmBa2Cu3Oy
J. H. Lee,김영철,D. Ahmad,김동진,정대영,I. S. Park,최민석,M. H. Sohn,장민수,Rock-Kil Ko,S. S. Ahn 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.4
The rare-earth superconductor TmBa2Cu3Ox(TmBCO) shows strong anisotropies in both para- magnetism and superconductivity. We discussed the eect of Tm3+ on the strong anisotropies of TmBCO. The magnetization (M) of TmBCO above the critical temperature (Tc) is very well described by the Brillouin function BJ (g¹BB=kBT) with J = 6, meaning that the paramagnetic signal of TmBCO is mainly generated from Tm3+ ions. The anisotropy of the magnetization values for T > Tc appears to be much stronger than that of YBCO. This can be explained by spin-orbit coupling of the two unpaired electrons of the Tm3+ ions in noncubic symmetry orbitals. From the superconducting signal below Tc, an anisotropy of the critical current density (Jcjj < Jc?) has been observed, where Jcjj and Jc? are the critical current densities measured under a .eld applied parallel to the c-axis (Hjj) and a .eld applied parallel to the ab-plane (H?), respectively. The super- conducting anisotropy can be explained by the local .eld intensity on the Cu-O planes depending on the spin alignment direction of the two unpaired electrons of the Tm3+ ion determined by H. In addition, Jc?(H) for H > 20 kOe increased a little as H increased, showing non-collective °ux pinning behavior. This means that the Tm3+ ions under H? serve as pinning centers in high .elds.ame=JP0
ON SOME GEOMETRIC PROPERTIES OF QUADRIC SURFACES IN EUCLIDEAN SPACE
( Ahmad T. Ali ),( H. S. Abdel Aziz ),( Adel H. Sorour ) 호남수학회 2016 호남수학학술지 Vol.38 No.3
This paper is concerned with the classifications of quadric surfaces of first and second kinds in Euclidean 3-space satisfying the Jacobi condition with respect to their curvatures, the Gaussian curvature K, the mean curvature H, second mean curvature H< sub >II< /sub > and second Gaussian curvature K< sub >II< /sub >. Also, we study the zero and non-zero constant curvatures of these surfaces. Furthermore, we investigated the (A, B)-Weingarten, (A, B)-linear Weingarten as well as some special (C2, K) and (C2, K □)-nonlinear Weingarten quadric surfaces in E< sup >3< /sup >, where A ≠ B, A, B ∈ {K, H, H< sub >II< /sub >, K< sub >II< /sub >} and C ∈ {H, H< sub >II< /sub >, K< sub >II< /sub >}. Finally, some important new lemmas are presented.
ON SOME GEOMETRIC PROPERTIES OF QUADRIC SURFACES IN EUCLIDEAN SPACE
Ali, Ahmad T.,Aziz, H.S. Abdel,Sorour, Adel H. The Honam Mathematical Society 2016 호남수학학술지 Vol.38 No.3
This paper is concerned with the classifications of quadric surfaces of first and second kinds in Euclidean 3-space satisfying the Jacobi condition with respect to their curvatures, the Gaussian curvature K, the mean curvature H, second mean curvature $H_{II}$ and second Gaussian curvature $K_{II}$. Also, we study the zero and non-zero constant curvatures of these surfaces. Furthermore, we investigated the (A, B)-Weingarten, (A, B)-linear Weingarten as well as some special ($C^2$, K) and $(C^2,\;K{\sqrt{K}})$-nonlinear Weingarten quadric surfaces in $E^3$, where $A{\neq}B$, A, $B{\in}{K,H,H_{II},K_{II}}$ and $C{\in}{H,H_{II},K_{II}}$. Finally, some important new lemmas are presented.
ZnO Nanonails: Synthesis and Their Application as Glucose Biosensor
Umar, Ahmad,Rahman, M. M.,Kim, S. H.,Hahn, Y. B. American Scientific Publishers 2008 Journal of Nanoscience and Nanotechnology Vol.8 No.6
<P>Well-crystallized zinc oxide nanonails were grown in a high density by thermal evaporation process and were used as supporting matrixes for glucose oxidase (GOx) immobilization to construct efficient glucose biosensor. The GOx attached to the surfaces of ZnO nanonails had more spatial freedom in its orientation, which facilitated the direct electron transfer between the active sites of immobilized GOx and electrode surface. The fabricated biosensor showed a high sensitivity of 24.613 <I>μ</I>A cm<SUP>-2</SUP> mM<SUP>-1</SUP> with a response time less than 10 s. Moreover, it shows a linear range from 0.1 to 7.1 mM with a correlation coefficient of R = 0.9937 and detection limit of 5 <I>μ</I>M.</P>
Shrestha, B.K.,Ahmad, R.,Mousa, H.M.,Kim, I.G.,Kim, J.I.,Neupane, M.P.,Park, C.H.,Kim, C.S. Academic Press 2016 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.482 No.-
A highly electroactive bio-nanohybrid film of polypyrrole (PPy)-Nafion (Nf)-functionalized multi-walled carbon nanotubes (fMWCNTs) nanocomposite was prepared on the glassy carbon electrode (GCE) by a facile one-step electrochemical polymerization technique followed by chitosan-glucose oxidase (CH-GOx) immobilization on its surface to achieve a high-performance glucose biosensor. The as-fabricated nanohybrid composite provides high surface area for GOx immobilization and thus enhances the enzyme-loading efficiency. The structural characterization revealed that the PPy-Nf-fMWCNTs nanocomposite films were uniformly formed on GCE and after GOx immobilization, the surface porosities of the film were decreased due to enzyme encapsulation inside the bio-nanohybrid composite materials. The electrochemical behavior of the fabricated biosensor was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry measurements. The results indicated an excellent catalytic property of bio-nanohybrid film for glucose detection with improved sensitivity of 2860.3μAmM<SUP>-1</SUP>cm<SUP>-2</SUP>, the linear range up to 4.7mM (R<SUP>2</SUP>=0.9992), and a low detection limit of 5μM under a signal/noise (S/N) ratio of 3. Furthermore, the resulting biosensor presented reliable selectivity, better long-term stability, good repeatability, reproducibility, and acceptable measurement of glucose concentration in real serum samples. Thus, this fabricated biosensor provides an efficient and highly sensitive platform for glucose sensing and can open up new avenues for clinical applications.
Ahmad, M.,Hashimoto, Y.,Moon, D.H.,Lee, S.S.,Ok, Y.S. Elsevier Scientific Pub. Co 2012 Journal of hazardous materials Vol.209 No.-
This study evaluated the effectiveness of eggshell and calcined eggshell on lead (Pb) immobilization in a shooting range soil. Destructive and non-destructive analytical techniques were employed to determine the mechanism of Pb immobilization. The 5% additions of eggshell and calcined eggshell significantly decreased the TCLP-Pb concentration by 68.8% due mainly to increasing soil pH. Eggshell and calcined-eggshell amendments decreased the exchangeable Pb fraction to ∼1% of the total Pb in the soil, while the carbonate-associated Pb fraction was increased to 40.0-47.1% at >15% application rates. The thermodynamic modeling on Pb speciation in the soil solution predicted the precipitation of Pb-hydroxide [Pb(OH)<SUB>2</SUB>] in soils amended with eggshell and calcined eggshell. The SEM-EDS, XAFS and elemental dot mapping revealed that Pb in soil amended with calcined eggshell was associated with Si and Ca, and may be immobilized by entrapping into calcium-silicate-hydrate. Comparatively, in the soil amended with eggshell, Pb was immobilized via formation of Pb-hydroxide or lanarkite [Pb<SUB>2</SUB>O(SO<SUB>4</SUB>)]. Applications of amendments increased activities of alkaline phosphatase up to 3.7 times greater than in the control soil. The use of eggshell amendments may have potential as an integrated remediation strategy that enables Pb immobilization and soil biological restoration in shooting range soils.
Ahmad, A.,Ali, T.,Park, H. Y.,Badshah, H.,Rehman, S. U.,Kim, M. O. HUMANA PRESS INC 2017 Molecular Neurobiology Vol.54 No.3
<P>Alzheimer's disease (AD) is a devastating and progressive neurodegenerative disease and is characterized pathologically by the accumulation of amyloid beta (A beta) and the hyperphosphorylation of tau proteins in the brain. The deposition of A beta aggregates triggers synaptic dysfunction, hyperphosphorylation of tau, and neurodegeneration, which lead to cognitive disorders. Here, we investigated the neuroprotective effect of fisetin in the A beta(1-42) mouse model of AD. Single intracerebroventricular injections of A beta(1-42) (3 mu l/5 min/mouse) markedly induced memory/synaptic deficits, neuroinflammation, and neurodegeneration. Intraperitoneal injections of fisetin at a dose of 20 mg/kg/day for 2 weeks starting 24 h after A beta(1-42) injection significantly decreased the A beta(1-42)-induced accumulation of A beta, BACE-1 expression, and hyperphosphorylation of tau protein at serine 413. Fisetin treatment also markedly reversed A beta(1-42)-induced synaptic dysfunction by increasing the levels of both presynaptic (SYN and SNAP-25) and postsynaptic proteins (PSD-95, SNAP-23, p-GluR1 (Ser 845), p-CREB (Ser 133) and p-CAMKII (Thr 286) and ultimately improved mouse memory, as observed in the Morris water maze test. Fisetin significantly activated p-PI3K, p-Akt (Ser 473), and p-GSK3 beta (Ser 9) expression in A beta(1-42)-treated mice. Moreover, fisetin prevented neuroinflammation by suppressing various activated neuroinflammatory mediators and gliosis; it also suppressed the apoptotic neurodegeneration triggered by A beta(1-42) injections in the mouse hippocampus. Fluorojade-B and immunohistochemical staining for caspase-3 revealed that fisetin prevented neurodegeneration in A beta(1-42)-treated mice. Our results suggest that fisetin has a potent neuroprotective effect against A beta(1-42)-induced neurotoxicity. These results demonstrate that polyphenolic flavonoids such as fisetin could be a beneficial, effective and safe neuroprotective agent for preventing neurological disorders such as AD.</P>
Impact of Environmental Factors on Birth Weight in Teddy Goat
Raza, S.H.,Tahir, M.,Zia, S.,Iqbal, Arshad,Ahmad, Shafiq Asian Australasian Association of Animal Productio 1998 Animal Bioscience Vol.11 No.2
The data 1241 birth, weights of Teddy goats maintained at Livestock Production Research Institute, Bahadurnagar, Okara, Pakistan, during 1975-1990 were used for this study. The mean birth weight during study period ranged from $1.55{\pm}0.06$ to $1.78{\pm}0.09kg$ with and over all mean of $1.66{\pm}0.031kg$. It was found that year of birth, type of birth, sex of kid and age of dam had significant (p < 0.01) effects on birth weight while the effect of season was found to be non-significant. It was inferred that single born kids were significantly heavier than twins and twins were heavier than triplets. The mean values of birth weight for male and female kids were $1.70{\pm}0.032$ and $1.61{\pm}0.03kg$ respectively. The birth weight was found to be the highest in 8 year age group that was $1.82{\pm}0.016kg$ and the lowest in one year group $(1.55{\pm}0.02kg)$.