Search results for "biophysic"
showing 10 items of 3565 documents
Three-dimensional crystallization of the light-harvesting complex from Mantoniella squamata (Prasinophyceae) requires an adequate purification proced…
1995
Abstract We present a new purification procedure for the light-harvesting complex of Mantoniella squamata whereupon three-dimensional crystallization succeeded. Previous purification methods were based on density centrifugations as the only separating principle. We have extended this preparation procedure by applying anion-exchange and molecular-sieve chromatography techniques. Purity and stability of the complex were proved by denaturing and non-denaturing polyacrylamide-gel electrophoresis, and spectroscopic measurements. With respect to contaminating lipids the purified pigment-protein complex was examined by thin-layer chromatography and the aggregation and/or oligomeric states were inv…
Systematic and statistical uncertainties of the hilbert-transform based high-precision FID frequency extraction method.
2021
Abstract Pulsed nuclear magnetic resonance (NMR) is widely used in high-precision magnetic field measurements. The absolute value of the magnetic field is determined from the precession frequency of nuclear magnetic moments. The Hilbert transform is one of the methods that have been used to extract the phase function from the observed free induction decay (FID) signal and then its frequency. In this paper, a detailed implementation of a Hilbert-transform based FID frequency extraction method is described, and it is briefly compared with other commonly used frequency extraction methods. How artifacts and noise level in the FID signal affect the extracted phase function are derived analytical…
How activator ion concentration affects spectroscopic properties on Ba4Y3F17: Er3+, Yb3+, a new perspective up-conversion material
2018
Abstract Ba4Y3F17 with Er3+ and Yb3+, a promising material for up-conversion luminescence, was synthesized. Excellent isomorphic capacity was detected. Low-temperature measurements show that erbium ions are incorporated in multiple lattice positions, which is inconsistent with the current model of Ba4Y3F17 crystal lattice structure. Activator ion concentration has a different impact on 4S3/2 and 4F9/2, states (for the green and red luminescence, respectively) depopulation. Energy transfer from Er3+ 4S3/2 state to Yb3+ is observed even at low temperature (15 K) while Er-Er cross-relaxation is observed from 120 K and above. Yb3+ concentration has a great impact to red-to-green up-conversion l…
On the ‘expanded local mode’ approach applied to the methane molecule: isotopic substitution CH2D2←CH4
2011
On the basis of a compilation of the ‘expanded local mode’ model and the general isotopic substitution theory, sets of simple analytical relations between different spectroscopic parameters (harmonic frequencies, ωλ, anharmonic coefficients, x λμ, ro-vibrational coefficients, , different kinds of Fermi- and Coriolis-type interaction parameters) of the CH2D2 molecule are derived. All of them are expressed as simple functions of a few initial spectroscopic parameters of the mother, CH4, molecule. Test calculations with the derived isotopic relations show that, in spite of a total absence of initial information about the CH2D2 species, the numerical results of the calculations have a very good…
High excitations in coupled-cluster series: vibrational energy levels of ammonia
2004
The ammonia molecule containing large amplitude inversion motion is a revealing system in examining high-order correlation effects on potential energy surfaces. Correlation contributions to the equilibrium and saddle point geometries, inversion barrier height and vibrational energy levels, including inversion splittings, have been investigated. A six-dimensional Taylor-type series expansion of the Born–Oppenheimer potential energy surface, which is scaled to different levels of theory, is used to determine vibrational energy levels and inversion splittings variationally. The electronic energies are calculated by coupled-cluster methods, combining explicitly correlated R12 theory (which incl…
MD Simulation Investigation on the Binding Process of Smoke-Derived Germination Stimulants to Its Receptor
2019
Karrikins (KARs) are a class of smoke-derived seed germination stimulants with great significance in both agriculture and plant biology. By means of direct binding to the receptor protein KAI2, the compounds can initiate the KAR signal transduction pathway, hence triggering germination of the dormant seeds in the soil. In the research, several molecular dynamics (MD) simulation techniques were properly integrated to investigate the binding process of KAR1 to KAI2 and reveal the details of the whole binding event. The calculated binding free energy, -7.00 kcal/mol, is in good agreement with the experimental measurement, -6.83 kcal/mol. The obtained PMF profile indicates the existence of thre…
Modellmembranen auf Oberflächen. Verankert und doch mobil
2008
Membranmodelle, die auf Festkorperoberflachen verankert sind, ermoglichen es, elektrische Verfahren sowie oberflachenanalytische und abbildende Methoden einzusetzen. So kann mit Membranen auf Oberflachen die laterale Organisation von Lipiden und Proteinen bis in den Nanometerbereich hinein visualisiert werden. Gleichzeitig sind diese Membranen sehr stabil und damit attraktiv fur verschiedene Bereiche der Biosensorik. Durch eine individuelle Adressierung kleinster mikrometergroser Membranareale mit verschiedenen Lipidkompositionen ist es moglich geworden, die Bindung von Proteinen an funktionale Membranen auf kleinstem Raum zu quantifizieren und zu parallelisieren. Fur die Untersuchung von T…
High-resolution stimulated Raman spectroscopy and analysis of the nu2, nu5 and 2 nu6 bands of 34SF6
2006
9 p.Special Issue: Nineteenth Colloquium on High Resolution Molecular Spectroscopy, Salamanca 11–16 September 2005
LAI, FAPAR and FCOVER ground-truth map creation from FASat-C satellite imagery and in-situ measurements in Chimbarongo, Chile, for satellite products…
2016
[EN] In remote sensing, validation exercises are essential to ensure the quality of the products originated from satellite Earth observations. To assess the measurement uncertainty derived from satellite products, several ground field data from different ecosystems must be available for use. In the same order of importance, it is necessary to define data sampling and up-scaling methodologies to allow a suitable comparison between the ground data and the pixel size of the product. This paper shows the applied methodology used in the FP7 ImagineS project (Implementing Multi-scale Agricultural Indicators Exploiting Sentinels) to validate 10-days global LAI, FAPAR and vegetation cover products …
Optimal modalities for radiative transfer-neural network estimation of canopy biophysical characteristics: Evaluation over an agricultural area with …
2011
International audience; Neural networks trained over radiative transfer simulations constitute the basis of several operational algorithms to estimate canopy biophysical variables from satellite reflectance measurements. However, only little attention was paid to the training process which has a major impact on retrieval performances. This study focused on the several modalities of the training process within neural network estimation of LAI, FCOVER and FAPAR biophysical variables. Performances were evaluated over both actual experimental observations and model simulations. The SAIL and PROSPECT radiative transfer models were used here to simulate the training and the synthetic test dataset…