排序方式: 共有28条查询结果,搜索用时 15 毫秒
1.
An efficient synthesis approach is developed which permits thecalculation of the steady-state frequency response of an assembly whichis comprised of linear components and nonlinear joints. Receptancematrices are used to characterize the linear components, which permitscondensation of the system to just the joint degrees-of-freedom.Furthermore, the calculated nonlinear joint forces are then used tostudy the power flow in the assembly, as well as detailed dynamicbehavior within the components. Integrated into the technique is acontinuation scheme which permits efficient parametric studies. 相似文献
2.
The accuracy and precision of photopeak area calculation methods has been studied by comparison of a digital method of computation
with the fitting of a mathematical function to the data. In the present study, peak areas for 16 replicate photopeaks were
computed both by the total peak area method any by the peak fitting method of program SAMPO. Both methods worked well with
the fitting method showing somewhat smaller spread in the results. 相似文献
3.
The determination of iodine in biological and environmental standard reference materials 总被引:1,自引:0,他引:1
H. L. Rook 《Journal of Radioanalytical and Nuclear Chemistry》1977,39(1-2):351-358
Iodine is an element with excellent intrinsic sensitivity when determined by thermal neutron activation. However, in most
real samples, the preponderance of chlorine and bromine, relative to iodine, makes the direct determination of iodine virtually
impossible. Over the past 20 years, there probably have been as many publications on the separation of iodine as there have
been for any other radionuclide. Upon review, however, the methods are essentially the same. After irradiation, the samples
are subjected to a rapid destructive process to free the iodine from the matrix and then the iodine is separated from the
other halides either by liquid-liquid extraction or by liquid ion exchange. Both of these procedures are, however, rather
complex and do not effect a complete separation of the halides in one pass. In the work presented here, a simple procedure
is described for the quantitative separation of iodine from chlorine. The procedure utilizes a gas phase separation on hydrated
manganese dioxide with iodine collected on silvered quartz wool. The described procedure has been used for the determination
of iodine in numerous new and old SRM's at the NBS. 相似文献
4.
Charles E. Nwankire Gerard G. Donohoe Xin Zhang Jonathan Siegrist Martin Somers Dirk Kurzbuch Ruairi Monaghan Maria Kitsara Robert Burger Stephen Hearty Julie Murrell Christopher Martin Martha Rook Louise Barrett Stephen Daniels Colette McDonagh Richard O’Kennedy Jens Ducrée 《Analytica chimica acta》2013
In this paper we report a centrifugal microfluidic “lab-on-a-disc” system for at-line monitoring of human immunoglobulin G (hIgG) in a typical bioprocess environment. The novelty of this device is the combination of a heterogeneous sandwich immunoassay on a serial siphon-enabled microfluidic disc with automated sequential reagent delivery and surface-confined supercritical angle fluorescence (SAF)-based detection. The device, which is compact, easy-to-use and inexpensive, enables rapid detection of hIgG from a bioprocess sample. This was achieved with, an injection moulded SAF lens that was functionalized with aminopropyltriethoxysilane (APTES) using plasma enhanced chemical vapour deposition (PECVD) for the immobilization of protein A, and a hybrid integration with a microfluidic disc substrate. Advanced flow control, including the time-sequenced release of on-board liquid reagents, was implemented by serial siphoning with ancillary capillary stops. The concentration of surfactant in each assay reagent was optimized to ensure proper functioning of the siphon-based flow control. The entire automated microfluidic assay process is completed in less than 30 min. The developed prototype system was used to accurately measure industrial bioprocess samples that contained 10 mg mL−1 of hIgG. 相似文献
5.
Henk Schierbeek Denise Rook Frans W. J. te Braake Kristien Y. Dorst Gardi Voortman Jean‐Philippe Godin Laurent‐Bernard Fay Johannes B. van Goudoever 《Rapid communications in mass spectrometry : RCM》2009,23(18):2897-2902
Determination of glutathione kinetics using stable isotopes requires accurate measurement of the tracers and tracees. Previously, the precursor and synthesized product were measured with two separate techniques, liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) and gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). In order to reduce sample volume and minimize analytical effort we developed a method to simultaneously determine 13C‐glutathione as its dimeric form (GSSG) and its precursor [1‐13C]glycine in a small volume of erythrocytes in one single analysis. After having transformed 13C‐glutathione into its dimeric form GSSG, we determined both the intra‐erythrocytic concentrations and the 13C‐isotopic enrichment of GSSG and glycine in 150 µL of whole blood using liquid chromatography coupled to LC/IRMS. The results show that the concentration (range of µmol/mL) was reliably measured using cycloleucine as internal standard, i.e. with a precision better than 0.1 µmol/mL. The 13C‐isotopic enrichment of GSSG and glycine measured in the same run gave reliable values with excellent precision (standard deviation (sd) <0.3‰) and accuracy (measured between 0 and 5 APE). This novel method opens up a variety of kinetic studies with relatively low dose administration of tracers, reducing the total cost of the study design. In addition, only a minimal sample volume is required, enabling studies even in very small subjects, such as preterm infants. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
6.
J.R. Rook 《Nuclear Physics A》1974,222(3):596-604
We use the impulse approximation, the Tabakin internucleon potential and a Fermi gas model for the nucleus to calculate the low energy nucleon-nucleus optical potential. The real and imaginary parts are calculated simultaneously but it is found to be an extremely good approximation to calculate them separately as is usually done. The main features of the real part of the isospin independent potential are reproduced by our calculation. We also estimate the size and shape of the asymmetry term in the real part of the potential. The size is in agreement with empirical analyses and the predicted shape may be useful as a guide when fitting data. Our calculations for the imaginary part are much less satisfactory. In particular we cannot reproduce the large surface peaking of the empirical potentials perhaps reflecting our neglect of collective states. We find that the observed difference between the imaginary parts for protons and neutrons cannot be explained as a consequence of a reasonable difference between the proton and neutron distributions in nuclei. 相似文献
7.
The enthalpy of hydrolysis of solid tungsten thiotetrafluoride, WF(in4)S, in aqueous sodium hydroxide solution is -528.2 kJ mo1-1. Hence its standard enthalpy of formation has been calculated to be -1150.5 kJ mo1-1. 相似文献
8.
Recent measurements of fine-structure splitting in \(\bar p\) atoms of174Yb are analysed. Effects of nuclear deformation are calculated. The strength of nuclear spin-orbit coupling is determined and its implications on theN \(\bar N\) potential are discussed. 相似文献
9.
G. J. Lutz J. S. Stemple H. L. Rook 《Journal of Radioanalytical and Nuclear Chemistry》1977,39(1-2):277-283
Low temperature ashing is a convenient first step in many procedures of analytical chemistry as well as a potential processing
method for storing environmental samples for extended periods of time. Using activation analysis, it is shown in a number
of NBS Standard Reference Materials that of some 40 elements studied, the only elements observed to be lost were osmium, mercury
and halogens along with carbon. No contamination during the ashing process was detected. 相似文献
10.
Rabindra N. Roy Julie A. Carlsten Jodi Niederschmidt William S. Good J. Michelle Rook Christina Brewe Amanda J. Kilker Lakshmi N. Roy Kathleen M. Kuhler 《Journal of solution chemistry》1997,26(3):309-317
ThepK
2
values for 3-[(l,l-Dimethyl-2-hydroxymethyl)amino]-2-hydroxypropanesulfonic acid (AMPSO), and 3-[N,N-Bis(-hydroxyethyl)amino]-2-hydroxypropanesulfonic
acid (DIPSO) have been determined at 12 temperatures over the range 5 to 55‡C by measurements of the emf of cells without
liquid junction containing hydrogen and silver-silver chloride electrodes. The values of pK
2 for AMPSO and DIPSO were found to be 9.138 and 7.576, respectively, at 25‡C. The thermodynamic quantities, δG‡, δH‡, δS‡,
and δC
p
‡
were calculated from the change of the equilibrium constants with temperature. These buffer substances are useful as secondary
pH standards in the physiological region of pH 7 to 9.
Camille and Henry Dreyfus Fellow, 1994–1996. 相似文献