In order to explore the isotope effect including the nuclear–electronic coupling and nuclear quantum effects under the one-particle
approximation, we apply the dynamic extended molecular orbital (DEMO) method and energy component analysis to the hydrogen
and lithium hydride isotope molecules. Since the DEMO method determines both electronic and nuclear wave functions simultaneously
by variationally optimizing all parameters embedded in the basis sets, the virial theorem is completely satisfied and guarantees
the relation of the kinetic and potential energies. We confirm the isotope effect on internuclear distances, nuclear and electronic
wave functions, dipole moment, the polarizability, and each energy component. In the case of isotopic species of the hydrogen
molecule, the total energy decreases from the H2 to the T2 molecule due to the stabilization of the nuclear–electronic potential component, as well as the nuclear kinetic one. In the
case of the lithium hydride molecule, the energy lowering by replacing 6Li with 7Li is calculated to be greater than that by replacing H with D. This is mainly caused by the small destabilization of electron–electron
and nuclear–nuclear repulsion in 7LiH compared to 6LiH, while the change in the repulsive components from 6LiH to 6LiD increases.
Received: 24 March 1999 / Accepted: 5 August 1999 / Published online: 15 December 1999 相似文献
Magnetic fluid applications require stability under demanding conditions. Complete magnetic fluids and their component surfactants and dispersing oils were irradiated. Their subsequent thermal oxidation was characterized by chemiluminescence and DSC. Except for polyisobutylsuccinic anhydride, irradiation sensitized the components toward oxidation. The components were ranked by stability. Complete fluids were more stable than would be predicted from their components suggesting that they may be used for nuclear applications.
Summary The structure of the sugar component of the new cardiac bioside securidaside, securidabiose, has been established; it is 4--(D-glucopyranosyl)-D-xylopyranose.Khimiya Prirodnykh Soedinenii, Vol. 3, No. 2, pp. 167–173, 1967 相似文献
The molecular imaging of paper cross sections containing the wet-strength additive poly(amidoamine)–epichlorohydrin (PAE) was effected by Fourier transform infrared (FT-IR) spectroscopic imaging. Thin cross sections of laboratory sheet samples were prepared and transferred onto CaF2 substrates. A laboratory sheet sample without PAE acted as a reference. Principal component analysis (PCA) was applied to identify and to reveal the distribution of PAE across the section. Differences in the loading plots of the fourth and fifth principal components for the sheets with and without PAE were found in the region of the amide I, amide II, and amine bands within a variance of 0.4–0.8 %. The score images of the PCA reveal inhomogeneous distribution of PAE. Small areas of higher concentration of PAE occur across the cross section. The aim of this study was to demonstrate that FT-IR spectroscopic imaging provides spatially resolved quantitative information about the chemical composition of paper, which was successfully achieved.
Figure
New analytical approach for imaging paper cross sections at molecular level 相似文献
Multivariate statistical analysis of sediment data (information matrix 123 × 16) from the Gulf of Mexico, USA shows that
the data structure is defined by four latent factors conditionally called “inorganic natural”, “inorganic anthropogenic”,
“bioorganic” and “organic anthropogenic” explaining 39.24%, 23.17%, 10.77% and 10.67% of the total variance of the data system,
respectively. The receptor model obtained by the application of the PCR approach makes it possible to apportion the contribution
of each chemical component for the latent factor formation. A separation of the contribution of each chemical parameter is
achieved within the frames of “natural” and “anthropogenic” origin of the respective heavy metal or organic matter to the
sediment formation process. This is a new approach as compared to the traditional “one dimensional” search with a limited
number of preliminary selected tracer components. The model suggested divides natural from anthropogenic influences and allows
in this way each participant in the sediment formation process to be used as marker of either natural or anthropogenic effects.
Received: 20 March 1999 / Revised: 1 June 1999 / Accepted: 3 June 1999 相似文献
Multivariate statistical analysis of sediment data (information matrix 123 × 16) from the Gulf of Mexico, USA shows that
the data structure is defined by four latent factors conditionally called “inorganic natural”, “inorganic anthropogenic”,
“bioorganic” and “organic anthropogenic” explaining 39.24%, 23.17%, 10.77% and 10.67% of the total variance of the data system,
respectively. The receptor model obtained by the application of the PCR approach makes it possible to apportion the contribution
of each chemical component for the latent factor formation. A separation of the contribution of each chemical parameter is
achieved within the frames of “natural” and “anthropogenic” origin of the respective heavy metal or organic matter to the
sediment formation process. This is a new approach as compared to the traditional “one dimensional” search with a limited
number of preliminary selected tracer components. The model suggested divides natural from anthropogenic influences and allows
in this way each participant in the sediment formation process to be used as marker of either natural or anthropogenic effects.
Received: 20 March 1999 / Revised: 1 June 1999 / Accepted: 3 June 1999 相似文献
A new component C15H22O3, has been isolated from the epigeal part ofArtemisia fragrans. On the basis of chemical transformations and spectral characteristics it has been established that it has the structure of 1-hydroxy-5,7H,6,11H-eudesm-3,4-en-6,12-olide (I).V. L. Komarov Institute of Botany, Academy of Sciences of the Azerbaidzhan SSR, Baku. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 632–635, September–October, 1990. 相似文献
Trace organometallic intermediates arising from complex organic syntheses are usually quite difficult to detect spectroscopically. In situ FTIR and in situ NMR are the only techniques that are used with any regularity for such studies. In this contribution, high-pressure in situ Raman spectroscopic measurements were performed for the rhodium catalyzed hydroformylation of 3,3-dimethylbut-1-ene using Rh4(CO)12 as catalyst precursor at 298 K – a reaction extensively studied previously by more sensitive in situ FTIR. The Raman spectroscopic measurements were analyzed using the band-target entropy minimization (BTEM) algorithm. As expected, the pure component spectra of dissolved CO, 3,3-dimethylbut-1-ene, and 4,4-dimethylpentanal were easily recovered. In addition, the pure component spectra of the precursor Rh4(CO)12 and the intermediate RCORh(CO)4 (R = (CH3)3CCH2CH2) were successfully reconstructed – even though the mean concentrations of both species were on the order of 150 ppm. The BTEM estimate of the Raman spectrum of RCORh(CO)4 is reported for the first time. This Raman spectrum is consistent with the DFT predicted spectrum. This study represents the first combined application of Raman spectroscopy and BTEM analysis to a homogeneously catalyzed metal-mediated reaction. The potential and limitations of this general approach are discussed. 相似文献
An approach to assess the permissible ranges for results of replicate determinations using uncertainty calculation is discussed.
The approach is based on the known range distribution for normalized "range/standard deviation" values, which is equivalent
to the distribution of the range for normalized results of replicate determinations having an average of 0 and a standard
deviation of 1. It is shown that the permissible ranges can be assessed using tabulated percentiles of this distribution and
calculated values of the determination (analysis) standard uncertainty. When the standard uncertainty calculation is performed
before the analytical method validation, the permissible ranges can be predicted. As an example, the range is predicted for
a new pH-metric method for acid number determination without titration in petroleum oils (basic, white and transformer). The
results of the prediction are in good conformity with the experimental data.
Received: 23 May 1999 · Accepted: 14 November 1999 相似文献
Cobalt(II) porphyrazine is synthesized and studied as an active component of a polyvinyl chloride plasticized membrane ion-selective electrodes (ISEs). It is established that regardless of their structure, ISEs are sensitive to iodide. The introduction to the ISE of an ionic additive, ionic liquid 1,3-dihexadecylimidazolium chloride, significantly improves the electrochemical characteristics: the slope of the electrode function reaches ?(57 ± 1) mV/dec, cmin = 8.3 × 10–6 M. Solid-state screen-printed electrodes the surfaces of which are modified by a 1: 4 mixture of cobalt(II) porphyrazine and ionic liquid 1,3-dihexadecylimidazolium chloride demonstrate satisfactory electrochemical characteristics: the slope of the electrode function is ?(56 ± 4) mV/dec and cmin = 2.5 × 10–5 M. The potentiometric selectivity of the ISEs for iodide is studied. It is found that the effect of lipophilic interfering ions is significantly lower for solid state ISEs than for plasticized membrane electrodes. 相似文献
Summary In the analysis of biological matrices, the application of o-phthaldialdehyde in the presence of a thiol component (OPA-method) for the quantitative determination of free - and -amino groups in amino acids, peptides and proteins as well as their hydrolytic or proteolytic products, respectively, is well known. The most frequently used thiol compound is mercaptoethanol. The use of this substance has the disadvantage that the initially generated isoindole often undergoes intramolecular rearrangement which often leads to a decrease in extinction at the monitoring wavelength of 340 nm. The present paper describes a modified method in which mercaptoethanol was replaced by N,N-dimethyl-2-mercaptoethylammonium chloride. The use of the new thiol component in the OPA reaction results in long-term stability of the extinction values (plateauing > 1 h). The modified method is further characterized by high accuracy and precision.
Modifizierte OPA-Methode mit N,N-Dimethyl-2-mercaptoethylammoniumchlorid als Thiolkomponente
The control and monitoring of an industrial process is performed in this paper by the multivariate control charts. The process analysed consists of the bottling of the entire production of 1999 of the sparkling wine "Asti Spumante". This process is characterised by a great number of variables that can be treated with multivariate techniques. The monitoring of the process performed with classical Shewhart charts is very dangerous because they do not take into account the presence of functional relationships between the variables. The industrial process was firstly analysed by multivariate control charts based on Principal Component Analysis. This approach allowed the identification of problems in the process and of their causes. Successively, the SMART Charts (Simultaneous Scores Monitoring And Residual Tracking) were built in order to study the process in its whole. In spite of the successful identification of the presence of problems in the monitored process, the Smart chart did not allow an easy identification of the special causes of variation which casued the problems themselves. 相似文献
The 0‐1 model‐inverse method of nonequilibrium nonlinear chromatography was developed to simultaneously determine the isotherm parameters and the lumped mass transfer coefficients of the two‐component systems in RPLC. By comparing the simulated elution curves with experimental curves with regard to profiles and areas, the suitable isotherm parameters and the lumped mass transfer coefficients were obtained with the 0‐1 model‐inverse method. With a solute cell unit width of cm, the average errors of the peak areas were 0.178% for one component and ?0.40% for two components, and the numerical diffusions of the 0‐1 model for the contribution to band broadening may be negligible. In addition, the results showed that the lumped mass transfer coefficients decrease as the solute concentration increases. The 0‐1 model‐inverse method has not only the advantages of high calculation speed (less than 10 min for one‐component systems or approximately 3 h for two‐component systems using an ordinary computer) and high accuracy in simultaneously obtaining thermodynamic parameters and kinetic parameters of two‐component systems, but this method also possesses the potential to optimally design and control the time‐variant preparative chromatographic system due to the thermodynamic state recursion and the Lagrangian‐Eulerian presentation of the 0‐1 model. 相似文献