scholarly journals Investigation of structure and vibrational properties of cyclobutane pirimidine dimer

2013 ◽  
Vol 67 (2) ◽  
pp. 203-207
Author(s):  
Milena Petkovic ◽  
Mihajlo Etinski ◽  
Miroslav Ristic
Keyword(s):  
Main Product ◽  
Harmonic Approximation ◽  
Precise Determination ◽  
Pyrimidine Dimer ◽  
Vibrational Properties ◽  
Symmetry Constraints ◽  
The Difference ◽  
Anharmonic Coupling ◽  
Gaussian Program

We performed a theoretical analysis of the structure and vibrational properties of cyclobutane pyrimidine dimer, which is the main product in a photochemical reaction involving two molecules of 1-methylthymine. Thymine is a pyrimidine base that has the highest yield of the dimerization photoproducts. Methylation in position one was chosen because in this position thymine is linked to sugar in DNA. The calculations were performed at the B3LYP/cc-pVTZ level with a Gaussian program package. All molecular geometries were optimized without symmetry constraints in vacuum and D2O. Vibrational frequencies were calculated in the harmonic approximation. It was shown that there are two stable isomers, CPD(cis-syn) and CPD(trans-syn). CPD(trans-syn) is more stable both in vacuum and in D2O. By dissolving these molecules in D2O, both structures become more stable, although the stabilization of the less stable isomer is more pronounced due to its larger dipole moment. Thus, the difference in stability of the two isomers in D2O is almost two times lower than in vacuum. Because of the similarity of the two isomers? structures, the difference in their vibrational spectra is not pronounced. Within the harmonic approximation, there is only a slight difference in the C=O and C-H stretching region. The difference in the N-H stretching region is more pronounced; in the CPD(cis-syn) molecule the two bonds vibrate separately, whereas in the CPD(trans-syn) the two modes couple, and this coupling results in symmetric and asymmetric N-H stretching. The observation shows that a slight difference in geometry can be reflected in the shape of the infrared spectra. A more detailed analysis of the vibrational properties would involve computation of anharmonic coupling terms, which would enable a more precise determination of the peak positions.

Precise Determination of Frequency Shifts by Raman Difference Spectroscopy Using Voigt Profile for the Raman Band

1983 ◽  
Vol 37 (4) ◽  
pp. 334-340 ◽  
Author(s):  
B. P. Asthana ◽  
W. Kiefer
Keyword(s):  
Frequency Shift ◽  
Raman Band ◽  
Precise Determination ◽  
Frequency Separation ◽  
Explicit Calculation ◽  
Graphical Form ◽  
Frequency Shifts ◽  
Voigt Profile ◽  
The Difference

A convenient method for the precise determination of the frequency shifts from experimentally obtained Raman difference spectra is described. The method is based on the explicit calculation of the difference curve taking Voigt profile for the Raman band. A relationship between Δ/T (Δ, frequency separation between two Raman bands, Γ, Raman bandwidth) and d/I0 ( d, peak-to-peak height in the difference spectrum; I0, Raman band height) is presented in a graphical form as a function of the band shape parameter Γ/Γ G [Γ G = (Δν1/2)slit: used slit width determined experimentally by measuring the half-bandwidth of a narrow plasma line]. The experimental determination of (Δν1/2)slit, Γ, d, and I0 then allows direct derivation of Δ/Γ from the graphically presented functions and consequently the actual frequency shift Δ. The value of Δ/Γ can usually be determined with a typical uncertainty of ±0.002 in the small frequency shift limit and ±0.005 for medium and large frequency shifts and these would determine the frequency shift, Δ, with a maximum uncertainty of ±0.02 cm−1. An example of experimental spectra has been analyzed in order to assess the utility of the present technique.

FRACTIONAL DETERMINATIONS OF URINARY 17-KETOSTEROIDS IN HYPEREMESIS GRAVIDARUM

1962 ◽  
Vol 41 (1) ◽  
pp. 123-128 ◽  
Author(s):  
Pentti A. Järvinen ◽  
Sykkö Pesonen ◽  
Pirkko Väänänen
Keyword(s):  
Hyperemesis Gravidarum ◽  
First Trimester ◽  
Control Group ◽  
Before And After ◽  
Daily Urine ◽  
First Trimester Of Pregnancy ◽  
The Difference

ABSTRACT The fractional determination of 17-ketosteroids in the daily urine was performed in nine cases of hyperemesis gravidarum and in four control cases, in the first trimester of pregnancy both before and after corticotrophin administration. The excretion of total 17-KS is similar in the two groups. Only in the hyperemesis group does the excretion of total 17-KS increase significantly after corticotrophin administration. The fractional determination reveals no difference between the two groups of patients with regard to the values of the fractions U (unidentified 17-KS), A (androsterone) and Rest (11-oxygenated 17-KS). The excretion of dehydroepiandrosterone is significantly higher in the hyperemesis group than in the control group. The excretion of androstanolone seems to be lower in the hyperemesis group than in the control group, but the difference is not statistically significant. The differences in the correlation between dehydroepiandrosterone and androstanolone in the two groups is significant. The high excretion of dehydroepiandrosterone and low excretion of androstanolone in cases of hyperemesis gravidarum is a sign of adrenal dysfunction.

THE SUBJECT FIELD OF INSTITUTIONAL EDUCATION: THE SENSE AND PROSPECTS OF DEVELOPMENT IN UKRAINE

2020 ◽  
pp. 25-38
Author(s):  
Irina Mordous
Keyword(s):  
Decisive Role ◽  
Subject Field ◽  
National Education ◽  
Progressive Development ◽  
Separate Area ◽  
Economic Transformations ◽  
The Difference ◽  
The Individual ◽  
Political Economic

The development of modern civilization attests to its decisive role in the progressive development of institutions. They identified the difference between Western civilization and the rest of the world. Confirmation of the institutional advantages of the West was its early industrialization. The genesis and formation of institutionalism in its ideological and conceptualmethodological orientation occurs as a process alternative to neoclassic in the context of world heterodoxia, which quickly spread in social science. Highlighting institutional education as a separate area of sociocultural activity is determined by the factor of differentiation of institutional theory as a whole. A feature of institutional education is its orientation toward the individual and his/her transformation into a personality. The content of institutional education is revealed through the analysis of the institution, which includes a set of established customs, traditions, ways of thinking, behavioral stereotypes of individuals and social groups. The dynamics of socio-political, economic transformations in Ukraine requires a review of the foundations of national education and determination of the prospects for its development in the 21st century in the context of institutionalism.

PRECISE DETERMINATION OF THE IRRATIONAL PRE-FERRED INTERFACE ORIENTATION BY TEM

2010 ◽  
Vol 46 (4) ◽  
pp. 411-417 ◽  
Author(s):  
Yang MENG ◽  
Lin GU ◽  
Wenzheng ZHANG
Keyword(s):  
Precise Determination ◽  
Interface Orientation

Nauwkeurige methode voor de aanwasbepaling van het grondvlak met behulp van de Pressler-boor

1968 ◽  
Vol 12 ◽  
Author(s):  
R. Goossens
Keyword(s):  
Basal Area ◽  
Precise Determination ◽  
Maximum Diameter ◽  
Precise Method ◽  
Maximum Radius ◽  
The Core ◽  
Two Parameters

A precise method for the determination of the increment of the  basal area using the PressIer bore. Refering to  previous research showing that the basal area of the corsica pine could be  characterized by an ellips, we present in this paper a precise method for the  determination of the increment of the basal area. In this method we determine  the direction of the maximum diameter, we measure this diameter and we take a  core in one of the points of tangency of the caliper with the measured tree.  The determination of the diameter perpendicular to the maximum diameter  finishes the work wich is to be done in the forest. From the classical  measurements effectuated on the core and from the measured diameters we can  then determine the form (V) and the excentricity (e). Substituting these two  parameters in the formula 2 or 2', we can also calculate the error of a  radius measured on the core with respect to the representative radius, This  error with them allow us to correct the measured value of the minimum or the  maximum radius and we will be able to do a precise determination of the  increment.

scholarly journals New high-pressure phases of Fe7N3 and Fe7C3 stable at Earth's core conditions: evidences for carbon–nitrogen isomorphism in Fe-compounds

RSC Advances ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 3577-3581 ◽  
Author(s):  
Nursultan Sagatov ◽  
Pavel N. Gavryushkin ◽  
Talgat M. Inerbaev ◽  
Konstantin D. Litasov
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Ab Initio ◽  
Structure Prediction ◽  
Harmonic Approximation ◽  
Crystal Structure Prediction ◽  
Earth’S Core ◽  
Earth's Core ◽  
Core Conditions

We carried out ab initio calculations on the crystal structure prediction and determination of P–T diagrams within the quasi-harmonic approximation for Fe7N3 and Fe7C3.

scholarly journals A single-step purification method for the precise determination of the antimony isotopic composition of environmental, geological and biological samples by HG-MC-ICP-MS

2021 ◽  
Author(s):  
Ferrari Colin ◽  
Resongles Eléonore ◽  
Freydier Rémi ◽  
Casiot Corinne
Keyword(s):  
Isotopic Composition ◽  
Biological Samples ◽  
Precise Determination ◽  
Single Step ◽  
Functionalized Silica ◽  
Purification Method ◽  
Silica Powder ◽  
Icp Ms ◽  
Single Step Purification

Thiol-functionalized silica powder allowed single-step purification of antimony for exploring stable Sb isotope signatures in the environment.

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