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排序方式: 共有134条查询结果,搜索用时 15 毫秒
81.
C. Faller G. Henze N. Stojko S. Saraeva K. Brainina 《Fresenius' Journal of Analytical Chemistry》1997,358(6):670-676
The paper describes the determination of tin by ASV using modified thick film electrodes. Three different types of electrodes
were developed: One modified with a mixture of Nafion and mercury(II)acetate, one modified with diethyldithiocarbamate (DDC)
or pyrrolidinedithiocarbamate (PDC) and mercury(II)acetate, and one modified with calomel. The analyte was accumulated on
the electrode surface after special electrochemical pretreatment of the modified electrode. After recording the voltammogram
the electrodes were electrochemically regenerated. By virtue of their lifetime and their measurement reproducibility, we preferred
the DDC and PDC modified electrodes. They can be used for months without changing their chemical characteristics. The linear
range for tin determination with these electrodes is between 1 and 100 μg/L; the detection limit was calculated as 0.9 μg/L.
The electrodes were applied to the direct determination of tin in different canned fruit juices without special sample pretreatment.
Received: 20 December 1996 / Revised: 11 March 1997 / Accepted: 13 March 1997 相似文献
82.
Alice Santoro Jenifer S. Calvo Manuel David Peris‐Díaz Artur Krel Gabriele Meloni Peter Faller 《Angewandte Chemie (International ed. in English)》2020,59(20):7830-7835
Copper complexes are of medicinal and biological interest, including as anticancer drugs designed to cleave intracellular biomolecules by O2 activation. To exhibit such activity, the copper complex must be redox active and resistant to dissociation. Metallothioneins (MTs) and glutathione (GSH) are abundant in the cytosol and nucleus. Because they are thiol‐rich reducing molecules with high CuI affinity, they are potential competitors for a copper ion bound in a copper drug. Herein, we report the investigation of a panel of CuI/CuII complexes often used as drugs, with diverse coordination chemistries and redox potentials. We evaluated their catalytic activity in ascorbate oxidation based on redox cycling between CuI and CuII, as well as their resistance to dissociation or inactivation under cytosolically relevant concentrations of GSH and MT. O2‐activating CuI/CuII complexes for cytosolic/nuclear targets are generally not stable against the GSH/MT system, which creates a challenge for their future design. 相似文献
83.
Dr. Alice Santoro Jenifer S. Calvo Manuel David Peris-Díaz Prof. Artur Krężel Prof. Gabriele Meloni Prof. Peter Faller 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(20):7904-7909
Copper complexes are of medicinal and biological interest, including as anticancer drugs designed to cleave intracellular biomolecules by O2 activation. To exhibit such activity, the copper complex must be redox active and resistant to dissociation. Metallothioneins (MTs) and glutathione (GSH) are abundant in the cytosol and nucleus. Because they are thiol-rich reducing molecules with high CuI affinity, they are potential competitors for a copper ion bound in a copper drug. Herein, we report the investigation of a panel of CuI/CuII complexes often used as drugs, with diverse coordination chemistries and redox potentials. We evaluated their catalytic activity in ascorbate oxidation based on redox cycling between CuI and CuII, as well as their resistance to dissociation or inactivation under cytosolically relevant concentrations of GSH and MT. O2-activating CuI/CuII complexes for cytosolic/nuclear targets are generally not stable against the GSH/MT system, which creates a challenge for their future design. 相似文献
84.
Thick-film graphite electrodes in stripping voltammetry 总被引:1,自引:0,他引:1
Kh. Brainina G. Henze N. Stojko N. Malakhova C. Faller 《Analytical and bioanalytical chemistry》1999,364(4):285-295
Various types of modified thick-film graphite electrodes are reviewed. Two modification options are available: either in situ modified or beforehand. Electrodes modified in situ by various organic compounds were used for the determination of W, Mo, Cr, Ni and Mn by adsorptive stripping voltammetry.
Insoluble inorganic salts, insoluble organic complexes or soluble compounds protected with Nafion were used for modification
of the electrode surface beforehand. These pre-conditioned electrodes permit quantification of Pb, Cd, Cu, Zn, Sn, As and
Hg ions. The detection limits of these elements were in the sub-μg/L range. The relative standard deviation did not exceed
10–15%. Measurements were made without deaeration of test solutions and normally without destroying small organic matter found
in surface waters. A number of characteristics, such as the formation of well-shaped peaks and stable increments of peaks
after standard additions, as well as elimination of the mechanical surface regeneration stage and metallic mercury or its
soluble salts from the analytical procedure and a long shelf-life of the electrodes make them promising for electroanalysis
and for application in portable field instruments.
Received: 16 November 1998 / Revised: 16 February 1999 / Accepted: 20 February 1999 相似文献
85.
S Rayaprol Krushna Mavani CM Thaker DS Rana Keka Chakravorty SK Paranjape M Ramanadham Nilesh A Kulkarni DG Kuberkar 《Pramana》2002,58(5-6):877-880
A new series of mixed oxide superconductors with the stoichiometric composition La2−x
Dy
x
Ca
y
Ba2Cu4+y
O
z
(x=0.0 − 0.5, y=2x) has been studied for structural and superconductiong properties. Our earlier studies on La2−x
(Y/Er)
x
Ca
y
Ba2Cu4+y
O
z
series, show a strong dependence of T
c on hole concentration (p
sh). In the present work, the results of the analysis of the neutron diffraction measurements at room temprerature on x=0.3 and 0.5 samples are reported. It is interesting to know that Ca substitutes for both La and Ba site with concomitant
displacement of La onto Ba site. Superconductivity studies show that maximum T
c is obtained for x=0.5, y=1.0 sample (T
c ∼ 75 K), for La1.5Dy0.5Ca1Ba2Cu5O
z
(La-2125). 相似文献
86.
J. D. Robertson W. B. Walters S. F. Faller C. A. Stone R. L. Gill A. Piotrowski 《Zeitschrift für Physik A Hadrons and Nuclei》1985,322(4):705-706
With the96Ru(58Ni,2pn) reaction we produced151Yb81 and studied its decay after online mass separation by γ-spectroscopic techniques. The decay populates the four positive parity single proton levels in the N=82 daughter nucleus151Tm and establishes Iπ=1/2+ for the so far unknown151Tm low spin isomer. Using BCS theory proton single particle energies for151Tm were extracted from the observed excitation energies. 相似文献
87.
We performed molecular dynamics simulations of the low-molecular weight organic glass former ortho-terphenyl in bulk and freestanding films. The main motivation is to provide molecular insight into the confinement effect without explicit interfaces. Based on earlier models of ortho-terphenyl we developed an atomistic model for bulk simulations. The model reproduces literature data both from simulations and experiments starting from specific volume and diffusivity to mean square displacement and radial distribution functions. After characterizing the bulk model we form freestanding films by the elongation and expansion method. These films give us the opportunity to study the dynamical heterogeneity near the glass transition through in-plane mobility and reorientation dynamics. We finally compare the model in bulk and under confinement. We found qualitatively a lower glass transition temperature for the freestanding film compared to the bulk. 相似文献
88.
S. Faller A. Khodjamirian Ch. Klein Th. Mannel 《The European Physical Journal C - Particles and Fields》2009,60(4):603-615
We derive new QCD sum rules for B→D and B→D
* form factors. The underlying correlation functions are expanded near the light-cone in terms of B-meson distribution amplitudes defined in HQET, whereas the c-quark mass is kept finite. The leading-order contributions of two- and three-particle distribution amplitudes are taken into
account. From the resulting light-cone sum rules we calculate all B→D
(*) form factors in the region of small momentum transfer (maximal recoil). In the infinite heavy-quark mass limit the sum rules
reduce to a single expression for the Isgur–Wise function. We compare our predictions with the form factors extracted from
experimental B→(*)
l
ν
l
decay rates fitted to dispersive parameterizations. 相似文献
89.
Harry H. Wasserman William T. Han John M. Schaus John W. Faller 《Tetrahedron letters》1984,25(29):3111-3114
Treatment of N-alkylazetidine 2-carboxylates with oxalyl chloride may yield acid chlorides, iminium salts or chloro-γ-lactams depending on the stereochemistry and nature of the substituents on the azetidine ring. 相似文献
90.