Search results for "Spectral"
showing 10 items of 3116 documents
A multifuctional nanoplatform for drug targeted delivery based on radiation-engineered nanogels
2020
Abstract Under a rational design, combining biologically active molecules, ligands to specific cell receptors and fluorescent, radioactive or paramagnetic labels into a single nano-object can bridge the unique properties of the individual components and improve conventional sensing, imaging and therapeutic efficacies. The validation of these functional nano-objects requires careful testing both in terms of physico-chemical properties and biological behaviour in vitro and in vivo, prior to translation into the clinic. Ionising radiation of aqueous polymer solutions is a viable strategy to produce multifunctional nanogels from aqueous solutions of hydrophilic polymers. By proper selection of …
Pulse EPR methods for studying chemical and biological samples containing transition metals
2006
This review discusses the application of pulse EPR to the characterization of disordered systems, with an emphasis on samples containing transition metals. Electron nuclear double-resonance (ENDOR), electron-spin-echo envelope-modulation (ESEEM), and double electron-electron resonance (DEER) methodologies are outlined. The theory of field modulation is outlined, and its application is illustrated with DEER experiments. The simulation of powder spectra in EPR is discussed, and strategies for optimization are given. The implementation of this armory of techniques is demonstrated on a rich variety of chemical systems: several porphyrin derivatives that are found in proteins and used as model s…
Calderón problem for the p-Laplace equation : First order derivative of conductivity on the boundary
2016
We recover the gradient of a scalar conductivity defined on a smooth bounded open set in Rd from the Dirichlet to Neumann map arising from the p-Laplace equation. For any boundary point we recover the gradient using Dirichlet data supported on an arbitrarily small neighbourhood of the boundary point. We use a Rellich-type identity in the proof. Our results are new when p 6 = 2. In the p = 2 case boundary determination plays a role in several methods for recovering the conductivity in the interior. peerReviewed
Lower rim arylation of calix[n]arenes with extended perfluorinated domains
2006
Abstract Exhaustive O-arylation of p-tert -butylcalix[ n ]arenes 2 ( n = 4–8) with an excess of 3-pentadecafluoroheptyl-5-pentafluorophenyl-1,2,4-oxadiazole 3 and K 2 CO 3 in refluxing acetonitrile provides an easy entry to a new family of perfluorinated calix[ n ]arenes 1 . The cyclic tetramer furnishes a mixture of cone , partial cone , and 1,2-alternate conformers, while the larger macrocycles afford single products. The structures of all new compounds are substantiated by NMR techniques and MALDI-TOF mass spectral data. Single-crystal X-ray diffraction studies on the pentamer derivative 1b reveal a distorted cone-in conformation of the calixarene cup.
Quantitative global mapping of terrestrial vegetation photosynthesis
2017
Although traditional remote sensing systems based on spectral reflectance can already provide estimates of the 'potential' photosynthetic activity of terrestrial vegetation through the quantification of total canopy chlorophyll content or absorbed photosynthetic radiation, the determination of the 'actual' photosynthetic activity of terrestrial vegetation requires information about how the absorbed light is used by plants, such as vegetation fluorescence, using very high spectral resolution spectroscopy in the range 650-800 nm. The Fluorescence Explorer (FLEX) mission, selected in November 2015 as the 8th Earth Explorer by the European Space Agency (ESA), carries the FLORIS spectrometer, wi…
Quantifying the Robustness of Vegetation Indices through Global Sensitivity Analysis of Homogeneous and Forest Leaf-Canopy Radiative Transfer Models
2019
Vegetation indices (VIs) are widely used in optical remote sensing to estimate biophysical variables of vegetated surfaces. With the advent of spectroscopy technology, spectral bands can be combined in numerous ways to extract the desired information. This resulted in a plethora of proposed indices, designed for a diversity of applications and research purposes. However, it is not always clear whether they are sensitive to the variable of interest while at the same time, responding insensitive to confounding factors. Hence, to be able to quantify the robustness of VIs, a systematic evaluation is needed, thereby introducing a widest possible variety of biochemical and structural heterogeneit…
Hyperspectral UAV-Imagery and photogrammetric canopy height model in estimating forest stand variables
2017
Remote sensing using unmanned aerial vehicle (UAV) -borne sensors is currently a highly interesting approach for the estimation of forest characteristics. 3D remote sensing data from airborne laser scanning or digital stereo photogrammetry enable highly accurate estimation of forest variables related to the volume of growing stock and dimension of the trees, whereas recognition of tree species dominance and proportion of different tree species has been a major complication in remote sensing-based estimation of stand variables. In this study the use of UAV-borne hyperspectral imagery was examined in combination with a high-resolution photogrammetric canopy height model in estimating forest v…
Remote Estimation of Canopy Water Content in Different Crop Types with New Hyperspectral Indices
2018
A diverse range of vegetation indices have earlier been developed for the remote estimation of canopy water content (CWC), but most of them are not universally applicable. The aim of this study is to define new indices valid for a wide variety of crop types, that allow to obtain CWC maps at a large spatial scale. These indices were developed based on PROSAIL simulations and then optimized with an experimental dataset (SPARC03; Barrax, Spain), which consists of field data including water content and other biophysical parameters collected for 6 different crops (lucerne, corn, potato, sugar beet, garlic and onion) and associated TOC reflectance spectra acquired by the HyMap airborne sensor. Sp…
Estimating chlorophyll content of crops from hyperspectral data using a normalized area over reflectance curve (NAOC)
2010
Abstract The Normalized Area Over reflectance Curve (NAOC) is proposed as a new index for remote sensing estimation of the leaf chlorophyll content of heterogeneous areas with different crops, different canopies and different types of bare soil. This index is based on the calculation of the area over the reflectance curve obtained by high spectral resolution reflectance measurements, determined, from the integral of the red–near-infrared interval, divided by the maximum reflectance in that spectral region. For this, use has been made of the experimental data of the SPARC campaigns, where in situ measurements were made of leaf chlorophyll content, LAI and fCOVER of 9 different crops – thus, …
A Mixture Modeling Approach to Estimate Vegetation Parameters for Heterogeneous Canopies in Remote Sensing
2000
In this article, we describe a reflectance model which parametrizes the reflectance of vegetation canopies from optical properties of leaves and soil, and dominant canopy structural parameters. The model assumes certain principles of geometric models, for example, that sensor integrates the radiance reflected from three components, plant, shaded soil, and illuminated soil. Its inversion provides compositional information of the ground surface that is linked with the interpretation of the linear spectral mixture modeling (LSMM). This model also offers the potential for retrieving other meaningful biophysical properties such as LAI. The model has been tested on simulated spectra of spectral m…