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311.
Malik Fariha Butt Saira Mujahid Nouman 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(2):683-690
Journal of Radioanalytical and Nuclear Chemistry - The stable isotopic contents of precipitation and deuterium excess (d-excess) data justified the hypothesis that two distinct vapor sources are... 相似文献
312.
We present new data on the even-parity Rydberg states of atomic thallium using two-step three-photon laser excitation technique in conjunction with a thermionic diode ion detector. Atoms are excited from the 6p 2P1/2 ground state to the 7p 2P1/2 intermediate state via two-photon excitation and subsequently promoted to the high lying ns 2 S1/2 and nd 2D3/2 Rydberg states. The first ionization potential of thallium is determined as 49,266.66(1) cm-1 using data for the ns 2 S1/2 (25 ≤ n ≤ 54) and nd 2D3/2 (24 ≤ n ≤ 65) Rydberg series. This value is believed to be more accurate because the contribution due to the hyperfine structure splitting of the 7p 2P1/2 state (0.07185 cm-1) is much smaller as compared to that of the 6p 2P1/2 ground state (0.711 cm-1). 相似文献
313.
We propose a cyclic refrigeration principle based on mesoscopic electron transport. Synchronous sequential tunneling of electrons in a Coulomb-blockaded device, a normal metal-superconductor single-electron box, results in a cooling power of approximately k(B)T x f at temperature T over a wide range of cycle frequencies f. Electrostatic work, done by the gate voltage source, removes heat from the Coulomb island with an efficiency of approximately k(B)T/Delta, where Delta is the superconducting gap parameter. The performance is not affected significantly by nonidealities, for instance by offset charges. We propose ways of characterizing the system and of its practical implementation. 相似文献
314.
Nausheen Nazir Muhammad Zahoor Riaz Ullah Essan Ezzeldin Gamal A. E. Mostafa 《Molecules (Basel, Switzerland)》2021,26(1)
In this study, catechin (CTN) isolated from Elaeagnus umbellata was evaluated for in vitro antioxidant potential and inhibition of carbohydrate digestive enzymes (α-amylase and α-glucosidase). The compound was also tested for its in vivo antidiabetic potential using Sprague-Dawley rats as experimental animals. The effects of various doses of catechin in STZ (Streptozotocin) induced diabetic rats on fasting blood glucose level, body weight, lipid parameters, hepatic enzymes, and renal functions were evaluated using the reported protocols. The CTN exhibited the highest percent antioxidant for free radical scavenging activity against DPPH and ABTS free radicals, and inhibited the activity of carbohydrate digestive enzymes (with percent inhibition values: 79 ± 1.5% α-amylase and 80 ± 1.1% α-glucosidase). Administration CTN and standard glibenclamide significantly decreased the fasting blood glucose level and increased the body weight in STZ-induced diabetic rats. CTN significantly decreased the different lipid parameters, hepatic, and renal function enzyme levels along with Hb1c level in diabetic rats, while significantly increasing the high-density lipoprotein (HDL) level with values comparable to the standard glibenclamide. Further, the altered levels of glutathione and lipid peroxides of liver and kidney tissues were restored (by CTN) to levels similar to the control group. CTN significantly increased the antioxidant enzyme activities, total content of reduced glutathione, and reduced the malondialdehyde (MDA) level in rat liver and kidney tissues homogenates, and also corrected the histopathological abnormalities, suggesting its antioxidant potential. 相似文献
315.
Ahmed E Malik A Afza N Riaz N Anis I Sharif A Farheen S Lodhi MA Choudhary MI 《Natural product research》2007,21(1):69-75
Haloxylase, the triglyceride (1), unsaturated fatty acid (2), and saturated fatty acid methyl ester (3) have been isolated from the chloroform-soluble fraction of Haloxylon recurvum. Their structures have been elucidated through spectroscopic studies and chemical transformation. All these compounds showed significant inhibitory activity against the enzyme chymotrypsin in a concentration dependent fashion. 相似文献
316.
Maisi VF Saira OP Pashkin YA Tsai JS Averin DV Pekola JP 《Physical review letters》2011,106(21):217003
We provide a direct proof of two-electron Andreev transitions in a superconductor-normal-metal tunnel junction by detecting them in a real-time electron counting experiment. Our results are consistent with ballistic Andreev transport with an order of magnitude higher rate than expected for a uniform barrier, suggesting that only part of the interface is effectively contributing to the transport. These findings are quantitatively supported by our direct current measurements in single-electron transistors with similar tunnel barriers. 相似文献
317.
Static and adaptive feedback control for synchronization of different chaotic oscillators with mutually Lipschitz nonlinearities 下载免费PDF全文
Muhammad Riaz Muhammad Rehan Keum-Shik Hong Muhammad Ashraf Haroon Ur Rasheed 《中国物理 B》2014,(11):227-235
This paper addresses the control law design for synchronization of two different chaotic oscillators with mutually Lipschitz nonlinearities. For analysis of the properties of two different nonlinearities, an advanced mutually Lipschitz condition is proposed. This mutually Lipschitz condition is more general than the traditional Lipschitz condition. Unlike the latter, it can be used for the design of a feedback controller for synchronization of chaotic oscillators of different dynamics. It is shown that any two different Lipschitz nonlinearities always satisfy the mutually Lipschitz condition. Applying the mutually Lipschitz condition, a quadratic Lyapunov function and uniformly ultimately bounded stability, easily designable and implementable robust control strategies utilizing algebraic Riccati equation and linear matrix inequalities, are derived for synchronization of two distinct chaotic oscillators. Furthermore, a novel adaptive control scheme for mutually Lipschitz chaotic systems is established by addressing the issue of adaptive cancellation of unknown mismatch between the dynamics of different chaotic systems. The proposed control technique is numerically tested for synchronization of two different chaotic Chua's circuits and for obtaining identical behavior between the modified Chua's circuit and the R6ssler system. 相似文献
318.
The present article highlights some preliminary investigations based on a convenient and inexpensive chemical method for preparing
novel poly (1-naphthylamine) (PNA) nanostructures in the presence of different alcohols. The effect of alcoholic medium on
the polymerization and morphology of PNA was investigated. Results revealed that nanomorphology can be controlled under appropriate
preparative conditions. The particle sizes thus obtained were of 5–50 nm exhibiting a much smaller range than polyaniline
nanoparticles synthesized under similar conditions. 相似文献
319.
Razzaq H Qureshi R Janjua NK Saira F Saleemi S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(5):1034-1040
In the present study CT complexes of 2-, 3- and 4-Picolines with (DDQ) 2, 3-dichloro-5, 6-dicyano parabenzoquinone (pi-acceptor) and (I(2)) Iodine (sigma-acceptor) have been investigated spectrophotometrically in three different solvents (CCl(4), CHCl(3) and CH(2)Cl(2)) at six different temperatures. The formation constants of the CT complexes were determined by the Benesi-Hildebrand equation. The thermodynamic parameters were calculated by Van(')t Hoff equation. The DeltaH degrees , DeltaG degrees and DeltaS degrees values are all negative implying that the formation of studied complexes is exothermic in nature. 相似文献
320.
采用溶胶-凝胶自动燃烧方法合成了镍铁-钯复合材料NiFe2O4-Pd的磁性纳米颗粒. 样品在800 ℃烧结6 h生成结晶相. X射线衍射证实样品呈尖晶石结构. 利用场发射扫描电子显微镜研究结构形态和纳米颗粒的大小. 饱和磁化强度在100和300 K时,随着钯含量增加达5%降低,但加入10%Pd时磁化强度突然上升. 相似文献