scholarly journals Symmetry of the Optical Phonons in LuVO4: A Raman Study

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 341 ◽  
Author(s):  
Peter Rafailov ◽  
Dimitre Dimitrov ◽  
Yen-Fu Chen ◽  
Chi-Shen Lee ◽  
Jenh-Yih Juang
Keyword(s):  
Vibrational Spectrum ◽  
Special Focus ◽  
Phonon Modes ◽  
Theory Analysis ◽  
Rotational Angle ◽  
First Order ◽  
Weak Scattering ◽  
Complete Assignment ◽  
Raman Study

A thorough analysis of the first-order vibrational spectrum of LuVO4 is presented by using polarized micro-Raman spectroscopy with special focus on the phonon modes with the weakest intensity and occasional controversial assignment. Group-theory analysis is carried out to demonstrate the determination of numbers and symmetries of the Raman active modes. Crystal- and correlation-field splitting effects in the vibrational spectrum of LuVO4 are discussed. Under conditions adjusted to minimize the birefringence effects we recorded, in each main scattering configuration, a series of Raman spectra in different sample orientations achieved by rotating the sample around the incident laser beam. The dependence of the Raman intensity on the rotational angle allowed us to identify the correct symmetry of the phonons with exceptionally weak scattering cross-section. A complete assignment of all twelve first-order Raman active phonons of LuVO4 is thus obtained.

Antithrombin-mediated Inhibition of Factor Vlla-Tissue Factor Complex by the Synthetic Pentasaccharide Representing the Heparin Binding Site to Antithrombin

1996 ◽  
Vol 76 (01) ◽  
pp. 005-008 ◽  
Author(s):  
Jean Claude Lormeau ◽  
Jean Pascal Herault ◽  
Jean Marc Herbert
Keyword(s):  
Binding Site ◽  
Tissue Factor ◽  
Residual Activity ◽  
Coagulation Factors ◽  
Heparin Binding ◽  
Experimental Conditions ◽  
First Order ◽  
Heparin Binding Site ◽  
Coagulant Activity

SummaryWe examined the effect of the synthetic pentasaccharide representing the minimal binding site of heparin to antithrombin on the antithrombin-mediated inactivation of factor Vila bound to tissue factor. This effect was compared to the effect of unfractionated heparin. Using purified recombinant human coagulation factors and either a clotting or an amidolytic assay for the determination of the residual activity of factor Vila, we showed that the pentasaccharide was an efficient antithrombin-dependent inhibitor of the coagulant activity of tissue factor-factor Vila complex. In our experimental conditions, assuming a mean MW of 14,000 for heparin, the molar pseudo-first order rate constants for ATIII-mediated FVIIa inhibition by ATIII-binding heparin and by the synthetic pentasaccharide were found to be similar with respective values of 104,000 ± 10,500 min-1 and 112,000 ± 12,000 min-1 (mean ± s.e.m., n = 3)

Statistical method of steepest improvement of response

2018 ◽  
Vol 84 (11) ◽  
pp. 74-87
Author(s):  
V. B. Bokov
Keyword(s):  
Statistical Method ◽  
Linear Model ◽  
Response Prediction ◽  
Initial Experiment ◽  
First Order ◽  
Prediction Response ◽  
Conditional Extremum ◽  
Order Polynomial ◽  
Limiting Values

A new statistical method for response steepest improvement is proposed. This method is based on an initial experiment performed on two-level factorial design and first-order statistical linear model with coded numerical factors and response variables. The factors for the runs of response steepest improvement are estimated from the data of initial experiment and determination of the conditional extremum. Confidence intervals are determined for those factors. The first-order polynomial response function fitted to the data of the initial experiment makes it possible to predict the response of the runs for response steepest improvement. The linear model of the response prediction, as well as the results of the estimation of the parameters of the linear model for the initial experiment and factors for the experiments of the steepest improvement of the response, are used when finding prediction response intervals in these experiments. Kknowledge of the prediction response intervals in the runs of steepest improvement of the response makes it possible to detect the results beyond their limits and to find the limiting values of the factors for which further runs of response steepest improvement become ineffective and a new initial experiment must be carried out.

Development and Validation of Derivative Spectroscopic Method for Simultaneous Estimation of Cefadroxil and Probenecid

2014 ◽  
Vol 7 (1) ◽  
pp. 2350-2355
Author(s):  
Pratik S Mehta ◽  
Pratik R. Patel ◽  
Rajesh R Parmar ◽  
M M K Modasiya ◽  
Dushyant A Shah
Keyword(s):  
Spectroscopic Method ◽  
Spectral Interference ◽  
Synthetic Mixture ◽  
Simultaneous Estimation ◽  
Zero Crossing ◽  
First Order ◽  
Derivative Spectroscopy ◽  
Development And Validation ◽  
Crossing Point

A novel, simple, accurate, sensitive, precise and economical derivative spectroscopic method was developed and validated for the determination of cefadroxil and probenecid in synthetic mixture. First order derivative spectroscopy method was adopted to eliminate spectral interference. The method obeys Beer’s Law in concentration ranges of 4-36 μg/ml for cefadroxil and of 5-25 μg/ml of probenecid. The zero crossing point for cefadroxil and probenecid was 260 nm and 237.8 nm respectively in 0.1N HCl. The method was validated in terms of accuracy, precision, linearity, limits of detection, limits of quantitation. This method has been successively applied to synthetic mixture and no interference from the synthetic mixture’s excipients was found.   

TERBIUM MOLYBDATE: GROUP THEORY AND FLUCTUATIONS

1987 ◽  
Vol 01 (05n06) ◽  
pp. 239-244
Author(s):  
SERGE GALAM
Keyword(s):  
Fixed Point ◽  
Group Theory ◽  
Parameter Space ◽  
Landau Theory ◽  
Two Dimensional ◽  
Stable Fixed Point ◽  
Theory Analysis ◽  
Continuous Transition ◽  
Dimensional Parameter ◽  
First Order

A new mechanism to explain the first order ferroelastic—ferroelectric transition in Terbium Molybdate (TMO) is presented. From group theory analysis it is shown that in the two-dimensional parameter space ordering along either an axis or a diagonal is forbidden. These symmetry-imposed singularities are found to make the unique stable fixed point not accessible for TMO. A continuous transition even if allowed within Landau theory is thus impossible once fluctuations are included. The TMO transition is therefore always first order. This explanation is supported by experimental results.

scholarly journals UV Spectrophotometric Simultaneous Determination of Paracetamol and Ibuprofen in Combined Tablets by Derivative and Wavelet Transforms

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Vu Dang Hoang ◽  
Dong Thi Ha Ly ◽  
Nguyen Huu Tho ◽  
Hue Minh Thi Nguyen
Keyword(s):  
Simultaneous Determination ◽  
Wavelet Transforms ◽  
Hybrid Approach ◽  
Uv Spectra ◽  
Order Derivative ◽  
First Order ◽  
Spectrophotometric Methods ◽  
Combined Use ◽  
Linear Concentration

The application of first-order derivative and wavelet transforms to UV spectra and ratio spectra was proposed for the simultaneous determination of ibuprofen and paracetamol in their combined tablets. A new hybrid approach on the combined use of first-order derivative and wavelet transforms to spectra was also discussed. In this application, DWT (sym6 and haar), CWT (mexh), and FWT were optimized to give the highest spectral recoveries. Calibration graphs in the linear concentration ranges of ibuprofen (12–32 mg/L) and paracetamol (20–40 mg/L) were obtained by measuring the amplitudes of the transformed signals. Our proposed spectrophotometric methods were statistically compared to HPLC in terms of precision and accuracy.

scholarly journals Diffraction Measurements and Equilibrium Parameters

2011 ◽  
Vol 2011 ◽  
pp. 1-14 ◽  
Author(s):  
Victor A. Sipachev
Keyword(s):  
Low Frequency ◽  
Mean Square ◽  
Structural Studies ◽  
Free Rotation ◽  
Theory Analysis ◽  
First Order ◽  
Internuclear Distances ◽  
The Mean ◽  
Asymmetry Parameters ◽  
First Order Perturbation

Structural studies are largely performed without taking into account vibrational effects or with incorrectly taking them into account. The paper presents a first-order perturbation theory analysis of the problem. It is shown that vibrational effects introduce errors on the order of 0.02 Å or larger (sometimes, up to 0.1-0.2 Å) into the results of diffraction measurements. Methods for calculating the mean rotational constants, mean-square vibrational amplitudes, vibrational corrections to internuclear distances, and asymmetry parameters are described. Problems related to low-frequency motions, including torsional motions that transform into free rotation at low excitation levels, are discussed. The algorithms described are implemented in the program available from the author (free).

scholarly journals Simultaneous determination of gatifloxacin and prednisolone acetate in ophthalmic formulation using first-order UV derivative spectroscopy

2017 ◽  
Vol 10 (5) ◽  
pp. 604-610 ◽  
Author(s):  
Rúbia A. Sversut ◽  
Isabella C. Alcântara ◽  
Aline M. Rosa ◽  
Adriano C.M. Baroni ◽  
Patrik O. Rodrigues ◽  
...  
Keyword(s):  
Simultaneous Determination ◽  
Prednisolone Acetate ◽  
First Order ◽  
Derivative Spectroscopy ◽  
Ophthalmic Formulation
Sign in / Sign up

Export Citation Format

Share Document