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排序方式: 共有894条查询结果,搜索用时 15 毫秒
21.
Ashok Kumar Singh Sameena Mehtab Udai P. Singh Vaibhave Aggarwal 《Electroanalysis》2007,19(11):1213-1221
New polymeric membrane cadmium‐ion selective sensors have been prepared by incorporating nitrogen and sulfur containing tridentate ligands as the ionophores into the plasticized PVC membranes. Poly(vinyl chloride) (PVC) based membranes of potassium hydrotris[N‐(2,6‐xylyl)thioimdazolyl) borate] (KTt2,6‐xylyl) and potassium hydrotris(3‐phenyl‐5‐methylpyrazolyl) borate (KTpPh,Me) with sodium tetraphenyl borate (NaTPB) as an anionic excluder and dibutylphthalate (DBP), tributylphthalate (TBP), dioctylsebacate (DOS), and o‐nitrophenyloctyl ether (o‐NPOE) as plasticizing solvent mediators were investigated in different compositions. KTt2,6‐xylyl was found to be a selective and sensitive ion carrier for Cd(II) membrane sensor. A membrane composed of KTt2,6‐xylyl:NaTPB:PVC:DBP with the % mole ratio 2.3 : 1.1 : 34.8 : 61.8 (w/w) works well over a very wide concentration range (7.8×10?8–1.0×10?2 M) with a Nernstian slope of 29.4±0.2 mV/decades of activity between pH values of 3.5 to 9.0 with a detection limit of 4.37×10?8 M. The sensor displays very good discrimination toward Cd(II) ions with regard to most common cations. The proposed sensor shows a short response time for whole concentration range (ca. 8 s). The effects of the cationic (tetrabutylammonium chloride, TBC), anionic (sodium dodecyl sulfate, SDS) and nonionic (Triton X‐100) surfactants were investigated on the potentiometric properties of proposed cadmium‐selective sensor. The proposed sensor based on KTt2,6‐xylyl ionophore has also been used for the direct determination of cadmium ions in different water samples and human urine samples. 相似文献
22.
S. B. Manohar S. K. Aggarwal S. M. Deshmukh A. R. Parab P. P. Burte H. C. Jain Satya Prakash 《Journal of Radioanalytical and Nuclear Chemistry》1981,63(1):145-153
A gamma-spectrometric method using an intrinsic high resolution germanium detector has been developed for the determination
of isotope ratios of plutonium from samples in solution form. The method is based on the assay of low energy gamma-rays of238Pu,239Pu,240Pu and241Pu and does not require the use of branching intensities or the knowledge of detection efficiencies for different gamma rays.
Since low energy gamma-rays are used, the effect of241Am has also been studied. It is found that results are not affected up to 0.5 wt% of241Am in plutonium samples. An accuracy of 3% is achievable in the determination of240Pu/239Pu and241Pu/239Pu atom ratios as demonstrated by carrying out measurements on isotopic standards of plutonium. 相似文献
23.
Summary
N-benzamidosalicylaldimine (H2L) complexes of CuII, NiII, CoII, FeII, MnII. VOIV and TiOIV have been prepared. The ligand probably coordinates to the metal from the hydroxyl, carbonyl and imino groups. 相似文献
24.
Leonard I. Wassenaar Liang-Feng Han Thomas Schiefer Gustav Kainz Luis Araguas-Araguas Pradeep K. Aggarwal 《Isotopes in environmental and health studies》2018,54(3):274-287
Tritium (3H) is an essential tracer of the Earth's water cycle; yet widespread adoption of tritium in hydrologic studies remains a challenge because of analytical barriers to quantification and detection of 3H by electrolytic pre-concentration. Here, we propose a simple tritium electrolytic enrichment system based on the use of solid polymer electrolyte membranes (PEMs) that can be used to enrich 3H in 250–3000?mL environmental water samples to a 10-mL final volume. The IAEA PEM-3H system reported here can produce high enrichment factors (>70-fold) and, importantly, removes some of the deterrents to conventional 3H enrichments methods, including the use of toxic electrolysis and neutralization chemicals, spike standards, a complex electrolysis apparatus that requires extensive cooling and temperature controls, and improves precision by eliminating the need for tracking recovery gravimetrics. Preliminary results with varying operating conditions show 3H enrichments to 70-fold and higher are feasible, spanning a wide range of tritium activities from 5 to 150 TU with a precision of ~4.5?%. Further work is needed to quantify inter-sample memory and to establish lower 3H detection limits. The IAEA PEM-3H system is open source, with 3-D CAD and design files made freely available for adoption and improvement by others. 相似文献
25.
Stacey M. Frumm Zi Peng Fan Kenneth N. Ross Jeremy R. Duvall Supriya Gupta Lynn VerPlank Byung-Chul Suh Edward Holson Florence F. Wagner William B. Smith Ronald M. Paranal Christopher F. Bassil Jun Qi Giovanni Roti Andrew L. Kung James E. Bradner Nicola Tolliday Kimberly Stegmaier 《Chemistry & biology》2013,20(5):713-725
26.
Reaction of 3-hydrazonobutan-2-one oxime with aromatic aldehydes resulted in the formation of 1,2-bis(arylidene)hydrazine commonly referred as azine as an unexpected product, instead of expected product 3-(aryl)methylenehydrazonobutan-2-one oxime, which were subsequently oxidized to corresponding aromatic acids with an ecofriendly oxidizing agent iodobenzene diacetate. Azines and carboxylic acids were characterized by IR and NMR (1H, 13C, HMBC, and HMQC) studies. 相似文献
27.
Condensation of uracil derivatives (1,3,4) with acetone in the presence of triethylamine gave pyranopyrimidines (2,5,6). 相似文献
28.
29.
This paper focuses on developing an area efficient hyperbolic Coordinate Rotation Digital Computer (CORDIC) algorithm with performance improvement. The algorithm eliminates the need of scale factor calculation in the Range of Convergence (ROC). At the same time the range of convergence offered is higher than the conventional CORDIC ROC in the hyperbolic rotation mode. Being the only kind of algorithm in hyperbolic rotation with sign sequence μ?=?1 always, one complete operation requires just 5 iterations. Thus the pipelined implementation has 5 stages which provides a 50% increase in throughput in comparison to conventional CORDIC. As far as the area improvement is considered, 16-bit processor can be realized using 56% less number of full adders required by Flat-CORDIC. The x and y datapath are based on series expansion of hyperbolic functions. The complete algorithm design along with pipelined architecture implementation is detailed. 相似文献
30.
Fabrication and Circuit Modeling of NMOS Inverter Based
on Quantum Dot Gate Field-Effect Transistors
Supriya Karmakar John A. Chandy Mukesh Gogna Faquir C. Jain 《Journal of Electronic Materials》2012,41(8):2184-2192
This paper presents the fabrication of a negative-channel metal–oxide–semiconductor (NMOS) inverter based on quantum dot gate field-effect transistors (QDG-FETs). A QDG-FET produces one intermediate state in its transfer characteristic. NMOS inverters based on a QDG-FET produce three states in their transfer characteristic. The generation of the third state in the inverter characteristic makes this a promising circuit element for multivalued logic implementation. A circuit simulation result based on the Berkley simulation (BSIM) circuit model of the QDG-FET is also presented in this paper, predicting the fabricated device characteristic. 相似文献