Conformation and Orientation of the Retinyl Chromophore in Rhodopsin:  A Critical Evaluation of Recent NMR Data on the Basis of Theoretical Calculations Results in a Minimum Energy Structure Consistent with All Experimental Data

Biochemistry ◽  
2001 ◽  
Vol 40 (14) ◽  
pp. 4201-4204 ◽  
Author(s):  
Deepak Singh ◽  
Bruce S. Hudson ◽  
Chris Middleton ◽  
Robert R. Birge
Keyword(s):  
Experimental Data ◽  
Theoretical Calculations ◽  
Minimum Energy ◽  
Critical Evaluation ◽  
Energy Structure ◽  
Nmr Data

scholarly journals Study of a Conformational Equilibrium of Lisinopril by HPLC, NMR, and DFT

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Sondes Bouabdallah ◽  
Med Thaieb Ben Dhia ◽  
Med Rida Driss
Keyword(s):  
Experimental Data ◽  
Thermodynamic Parameters ◽  
Conformational Equilibrium ◽  
Theoretical Calculations ◽  
Nmr Data ◽  
Major Species ◽  
B3lyp Calculations

The isomerization of lisinopril has been investigated using chromatographic, NMR spectroscopic, and theoretical calculations. The NMR data, particularly the NOEDIFF experiments, show that the major species that was eluted first is thetransform. The proportion was 77% and 23% for thetransandcis, respectively. The thermodynamic parameters (ΔH,ΔS, andΔG) were determined by varying the temperature in the NMR experiments. The interpretations of the experimental data were further supported by DFT/B3LYP calculations.

scholarly journals Uso de Cálculos de RMN de 13C e 1H e Redes Neurais no Auxilio da Determinação Estrutural da Savinina

2020 ◽  
Author(s):  
Evani Ferreira Cardoso ◽  
Rodrigo de Souza Miranda ◽  
Roberto Carlos Campos Martins ◽  
Gunar Vingre da Silva Mota ◽  
Antônio Maia de Jesus Chaves Neto ◽  
...  
Keyword(s):  
Neural Network ◽  
Experimental Data ◽  
Immune System ◽  
1H Nmr ◽  
Theoretical Calculations ◽  
Human Colon ◽  
Human Colon Carcinoma ◽  
Nmr Data ◽  
The Neural Network ◽  
Hct116 Cells

This is a theoretical-experimental work, where the focus molecule of the study is savinine, a lignan of the dibenzylbutyrolactonic type, substances that can be found in several genera, one of which has a greater occurrence is the genus Acanthopanax (Araliaceae) which is traditionally used as an analgesic and immune system stimulant, in addition to exhibiting a potent insecticidal and cytotoxic activity for human colon carcinoma HCT116 cells. It was isolated and here we present its experimental and theoretical characterization by means of 13C and 1H NMR data and the possible confirmation of the structure using the neural network tool (ANN-PRA). The objective of this work is to use theoretical calculations of 13C and 1H NMR and experimental data for the resolution of the savinine structure, and the use of the neural network tool (ANN-PRA) to confirm the structure of the molecule.

scholarly journals Determination of the enol form of asymmetric 1,3-dicarbonyl compounds: 2D HMBC NMR data and DFT calculations

2018 ◽  
Vol 83 (9) ◽  
pp. 953-968
Author(s):  
Meltem Tan ◽  
İshak Bildirici ◽  
Nurettin Mengeş
Keyword(s):  
Experimental Data ◽  
Driving Force ◽  
Theoretical Calculations ◽  
Enol Form ◽  
Dihedral Angles ◽  
Dicarbonyl Compounds ◽  
1H And 13C Nmr ◽  
Nmr Data ◽  
Cdcl3 Solution

In this study, a series of asymmetric aryl 1,3-dicarbonyl compounds were synthesized and their enol forms were observed via experimental data and theoretical calculations. According to the 1H- and 13C-NMR results, all the investigated compounds were found as a single enol form in CDCl3 solution. Moreover, their HMBC spectra were applied to identify the observed enol forms and correlations between certain protons and carbon atoms were considered. The dihedral angles of the asymmetric compounds that have aryl units on both sides were calculated by DFT to understand the reason for the observed enol forms. Small dihedral angles caused longer conjugation, resulting in more stable compounds and it was found that the observed enol forms were based on small dihedral angles, namely, resonance is the driving force. Furthermore, the compounds possessing both aryl and alkyl moieties prefer the enol form towards the aromatic ring side due to longer conjugation.

scholarly journals RNA Secondary Structures with Limited Base Pair Span: Exact Backtracking and an Application

Genes ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 14
Author(s):  
Ronny Lorenz ◽  
Peter F. Stadler
Keyword(s):  
Base Pair ◽  
Structure Prediction ◽  
Secondary Structure Prediction ◽  
Minimum Energy ◽  
Optimal Structure ◽  
Energy Structure ◽  
C Elegans ◽  
Z Scores ◽  
Limited Base ◽  
Optimal Span

The accuracy of RNA secondary structure prediction decreases with the span of a base pair, i.e., the number of nucleotides that it encloses. The dynamic programming algorithms for RNA folding can be easily specialized in order to consider only base pairs with a limited span L, reducing the memory requirements to O(nL), and further to O(n) by interleaving backtracking. However, the latter is an approximation that precludes the retrieval of the globally optimal structure. So far, the ViennaRNA package therefore does not provide a tool for computing optimal, span-restricted minimum energy structure. Here, we report on an efficient backtracking algorithm that reconstructs the globally optimal structure from the locally optimal fragments that are produced by the interleaved backtracking implemented in RNALfold. An implementation is integrated into the ViennaRNA package. The forward and the backtracking recursions of RNALfold are both easily constrained to structural components with a sufficiently negative z-scores. This provides a convenient method in order to identify hyper-stable structural elements. A screen of the C. elegans genome shows that such features are more abundant in real genomic sequences when compared to a di-nucleotide shuffled background model.

Cross sections for d-3H neutron interactions with samarium isotopes

2016 ◽  
Vol 104 (8) ◽  
Author(s):  
Junhua Luo ◽  
Chunlei Wu ◽  
Li Jiang ◽  
Long He
Keyword(s):  
Experimental Data ◽  
Neutron Flux ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Nuclear Model ◽  
Activation Technique ◽  
Incident Neutron ◽  
Reaction Threshold ◽  
Talys 1.6 ◽  
The Cross

Abstract:The cross sections for (n,x) reactions on samarium isotopes were measured at (d-T) neutron energies of 13.5 and 14.8 MeV with the activation technique. Samples were activated along with Nb and Al monitor foils to determine the incident neutron flux. Theoretical calculations of excitation functions were performed using the nuclear model codes TALYS-1.6 and EMPIRE-3.2 Malta with default parameters, at neutron energies varying from the reaction threshold to 20 MeV. The results were discussed and compared with experimental data found in the literature. At neutron energies 13.5 and 14.8 MeV, the cross sections of the

Pseudopotential calculations of elastic scattering of electrons by helium atoms in the range 0–20 eV

1990 ◽  
Vol 68 (1) ◽  
pp. 104-110 ◽  
Author(s):  
B. Plenkiewicz ◽  
P. Plenkiewicz ◽  
J.-P. Jay-Gerin
Keyword(s):  
Experimental Data ◽  
Elastic Scattering ◽  
Momentum Transfer ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Incident Electron ◽  
Elastic Electron ◽  
Scattering System ◽  
Helium Atoms ◽  
Pseudopotential Calculations

Our earlier pseudopotential calculations on electrons colliding with argon and krypton are extended to consider the elastic electron–helium scattering system. In this paper, we present detailed results for phase shifts, differential, total, and momentum-transfer cross sections for this system for incident electron energies in the range from 0 to 20 eV. These agree very well with existing experimental data and with other theoretical calculations.

A Comparison of Analytical Predictions With Experimental Measurements of Transmission Error of Misaligned Loaded Gears

1992 ◽  
Author(s):  
Harsh Vinayak ◽  
Donald R. Houser
Keyword(s):  
Experimental Data ◽  
Load Distribution ◽  
Theoretical Calculations ◽  
Data Acquisition System ◽  
Transmission Error ◽  
Test Facility ◽  
Experimental Measurements ◽  
Gear Pair ◽  
Prediction Program ◽  
Dynamic Transmission Error

Abstract This paper deals with the experimental study of dynamic transmission error of a gear pair. Two aspects of the experiment are discussed : 1) design of the test facility and data acquisition system and 2) comparison of transmission error and load distribution with experimental data. Several gears were tested under varying misalignments. A prediction program LDP (Load distribution Program) was used for theoretical calculations of dynamic transmission error.

Development of designing and implementation method of magnetic execution unit of downhole valve for the bottomhole assembly

2020 ◽  
pp. 38-44
Author(s):  
I.Y. Shirali ◽  
◽  
V.Yu. Tsivilitsin ◽  
İ.B. Bondar ◽  
R.A. Hasanov ◽  
...  
Keyword(s):  
Experimental Data ◽  
Theoretical Calculations ◽  
Calculation Methods ◽  
Well Drilling ◽  
Power Characteristics ◽  
Drilling Tools ◽  
Execution Unit ◽  
Implementation Method ◽  
Oil Gas ◽  
Gas Bearing

The structure of two types of magnetic valve is offered and the calculation methods of their pull-in force developed as well. The formulas of calculation of pull-in force in the main area of valves’ power characteristics are obtained. Experimental data are in alignment with theoretical calculations. Power characteristics of offered structures of magnetic valves may be changed in terms of the offered structural execution of magnetic valves. Experimental test of obtained formulas has been carried out. The ways of changing the power characteristics of magnetic valves in accordance with the requirements of certain applications are presented. The structures of magnetic reversing valves for drilling tools used in well drilling in various oil-gas bearing areas of SOCAR have been developed.

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