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941.
Hossein Farsi Fereydoon Gobal Heidar Raissi Shokufeh Moghiminia 《Journal of Solid State Electrochemistry》2010,14(4):643-650
Nanostructured molybdenum oxide having a particle size in the range of 30–80 nm was prepared by potentiodynamic electrodeposition
method, and the effects of H2SO4 concentration on its capacitive behavior were studied by cyclic voltammetry, galvanostatic discharge, and electrochemical
impedance spectroscopy. Poor to fair capacitive behaviors were witnessed depending on the electrolyte concentration and conditions
of charge/discharge. Increasing acid concentration to 0.02 M had favorable effect, while beyond that, the effect was detrimental.
Capacitance around 600 F g−1 was recorded in the potential range of 0 to −0.55 V vs. Ag/AgCl. 相似文献
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The first enantioselective synthesis of erogorgiaene (1), an inhibitor of mycobacterium tuberculosis, is disclosed. The total synthesis highlights the utility of asymmetric conjugate additions (ACA) of alkylzincs to acyclic alpha,beta-unsaturated ketones catalyzed by peptidic phosphine ligands and (CuOTf)(2).C(6)H(6). Moreover, several critical attributes of this catalytic C-C bond-forming reaction are illustrated in the context of the total synthesis; these include the significance of various structural features of the amino acid-based chiral ligands and the chiral ligand's effectiveness in reactions involving achiral and chiral substrates. In addition, the total synthesis showcases some of the special properties of nonphosphine Ru complex 3 as a highly effective catalyst for olefin cross-metathesis. 相似文献
947.
Kathleen L. Caldwell Amir Makhmudov Robert L. Jones Joseph G. Hollowell 《Accreditation and quality assurance》2005,10(7):356-361
In 2001 the Centers for Disease Control and Prevention (CDC) established a program, Ensuring the Quality of Urinary Iodine
Procedures (EQUIP); to assist laboratories around the world and assess the accuracy of their urinary iodine (UI). CDC designed
EQUIP to issue unknown specimens to participating laboratories three times per year. Each laboratory was asked to analyze
unknown samples in duplicate on three different days. During the first five rounds of EQUIP, 41 laboratories participated,
measuring unknown samples and reporting their results to CDC. CDC used these results to prepare a statistical report for the
laboratories. Feedback to the laboratories provided external confirmation regarding performance. As a group, laboratory performance
improved; several laboratories made considerable improvement. Several laboratories that showed no improvement have ordered
new equipment or are arranging for additional training. EQUIP is a key tool used to support laboratory quality assurance in
an effort to eliminate iodine deficiency disorders (IDD) in the world.
相似文献
Kathleen L. CaldwellEmail: |
948.
Vogel MJ Miraghaie R Lopez JM Hirsa AH 《Langmuir : the ACS journal of surfaces and colloids》2004,20(14):5651-5654
Insoluble monolayers on water have been patterned at the macroscopic scale (i.e., at the centimeter scale of the flow apparatus) as well as the mesoscopic scale (i.e., down to the micron scale resolvable via optical microscopy). The macroscopic patterning at the air/water interface results from a hydrodynamic instability leading to a steadily precessing flow pattern. The velocity field is measured, and the associated shear stress at the interface is shown to be locally amplified by the flow pattern. The resulting hydrodynamic effects on two different monolayer systems are explored: (1) the pattern in a model monolayer consisting of micron-size, surface-bound particles is visualized to show that the particles are concentrated into isolated regions of converging flow with high shear, and (2) Brewster angle microscopy of a Langmuir monolayer (vitamin K1) shows not only that the monolayer is patterned at the macroscopic scale but also that the localized high-shear flow further patterns the monolayer at the mesoscale. 相似文献
949.
Amino acid-based chiral ligands have been developed for use in Cu-catalyzed enantioselective allylic alkylations and conjugate additions that allow access to optically enriched compounds that are otherwise difficult to prepare. These chiral ligands are easily modified and have been identified through mechanism-based library screening. The data presented point to the significance of the availability of a collection of catalysts, since subtle variations in substrate or nucleophile structure often call for a different optimal chiral ligand. Can a catalyst be truly "rationally designed" or do we design our search pathway that eventually leads us to such a catalyst? What is meant by a "general catalyst"? Do we need a class of effective catalysts instead? These and related questions are addressed in the context of the above studies. 相似文献
950.
Ahmad VU Hussain J Hussain H Jassbi AR Ullah F Lodhi MA Yasin A Choudhary MI 《Chemical & pharmaceutical bulletin》2003,51(6):719-723
Three new diterpene esters with a myrsinol-type skeleton have been isolated from Euphorbia decipiens BOISS. & BUHSE. The structure elucidation of the isolated compounds was based primarily on two-dimensional (2D)-NMR techniques including correlation spectroscopy (COSY), heteronuclear multiple quantum coherence (HMQC), heteronuclear multiple bond correlation (HMBC) and nuclear Overhauser effect spectroscopy (NOESY) experiments. Compounds 1 and 3 are active against prolyl endopeptidase and compound 2 showed inhibitory activity against urease enzyme. 相似文献