Search results for "SPECTRA"

Melanoma-Nevus Discrimination Based on Image Statistics in Few Spectral Channels

2016

The purpose of this paper is to offer a method for discrimination of cutaneous melanoma from benign nevus, founded on analysis of skin lesion image. At the core of method is calculation of mean and standard deviation of pixel optical density values for a few narrow spectral bands. Calculated values are compared with discriminating thresholds derived from a set of images of benign nevi and melanomas with known diagnosis. Classification is done applying weighted majority rule to results of thresholding. Verification against the available multispectral images of 32 melanomas and 94 benign nevi has shown that the method using three spectral bands provided zero false negative and four false posi…

Heat- and pH-induced BSA conformational changes, hydrogel formation and application as 3D cell scaffold

2016

Aggregation and gelation of globular proteins can be an advantage to generate new forms of nanoscale biomaterials based on the fibrillar architecture. Here, we report results obtained by exploiting the proteins' natural tendency to self-organize in 3D network, for the production of new material based on BSA for medical application. In particular, at five different pH values the conformational and structural changes of the BSA during all the steps of the thermal aggregation and gelation have been analyzed by FTIR spectroscopy. The macroscopic mechanical properties of these hydrogels have been obtained by rheological measurements. The microscopic structure of the gels have been studied by AFM…

Analyzing the feasibility of time correlated spectral entropy for the assessment of neuronal synchrony

2016

In this paper, we study neuronal network analysis based on microelectrode measurements. We search for potential relations between time correlated changes in spectral distributions and synchrony for neuronal network activity. Spectral distribution is quantified by spectral entropy as a measure of uniformity/complexity and this measure is calculated as a function of time for the recorded neuronal signals, i.e., time variant spectral entropy. Time variant correlations in the spectral distributions between different parts of a neuronal network, i.e., of concurrent measurements via different microelectrodes, are calculated to express the relation with a single scalar. We demonstrate these relati…

Thermostabilization of BSA in TMAO Water Mixtures by Infrared Spectroscopy

2019

Background:Trimethylamine-N-Oxide (TMAO) is a small organic molecule derived from the metabolism of L-carnitine and choline after ingestion of animal food. TMAO has many functions such as electron acceptor, an osmolyte, stabilizer of macromolecules folding. It seems that TMAO plays an important role in nature but, in humans, it is a remnant of the evolution of the osmolyte system.Objective:The present paper is addressed on the study of thermal stability of hydrated Bovine Serum Albumins (BSA) in the presence of water and TMAO water solution by means of InfraRed spectroscopy. In particular, this work has investigated the protein amide I spectral regions, which is sensitive to protein seconda…

Compensation of Oxygen Transmittance Effects for Proximal Sensing Retrieval of Canopy–Leaving Sun–Induced Chlorophyll Fluorescence

2018

Estimates of Sun–Induced vegetation chlorophyll Fluorescence (SIF) using remote sensing techniques are commonly determined by exploiting solar and/or telluric absorption features. When SIF is retrieved in the strong oxygen (O 2 ) absorption features, atmospheric effects must always be compensated. Whereas correction of atmospheric effects is a standard airborne or satellite data processing step, there is no consensus regarding whether it is required for SIF proximal–sensing measurements nor what is the best strategy to be followed. Thus, by using simulated data, this work provides a comprehensive analysis about how atmospheric effects impact SIF estimations on proximal sensing, regarding: (…

The metabolites of the genus onopordum (asteraceae): Chemistry and biological properties

2011

Onopordum is an interesting genus belonging to the tribe Cardueae (Asteraceae family), and the species of this genus are used as food and in the popular medicine of several countries. The present paper reviews all the metabolites present in all the species of this genus, reported up to 2009, and several chemotaxonomic consideration have been made. Furthermore, the occurrence in other genus, the spectral data, the synthetic approaches, the chemical modifications and the biological properties of the sesquiterpenes of genus Onopor- dum have been reviewed.

Nonlinear Raman Spectroscopy in Gases

1992

0022-2860; Recent progress in high-resolution non-linear coherent Raman spectroscopy in the gas phase is reviewed. An instrumental spectral resolution of less than 100 MHz can be routinely achieved. It is limited by the convoluted linewidths of the lasers used for excitation and is of particular advantage in the gas phase, where the rotational structure of vibrational bands is to be resolved. It also allows the measurement of linewidths and line positions with an accuracy of 60 MHz when an appropriate wavemeter is used for calibration. After a short overview of the various techniques being used, examples of recent results of the evaluation of measurements on nitrogen, oxygen, carbon dioxide…

Preparation and structural characterization of organotin(IV) complexes with ligands containing a hetero {N} atom and a hydroxy group or hydroxy and c…

2005

AbstractTwenty-two n-butyltin(IV) and t-butyltin(IV) complexes of ligands containing an –OH (–C@O) group or –OH and –COOHgroups and an aromatic {N} donor atom were prepared by metathetical reactions. On the basis of the FT-IR and Mo¨ssbauer spec-troscopic data, molecular structures were assigned to these compounds. The binding sites of the ligands were identified by means ofFT-IR spectroscopic measurements, and it was found that in most cases the organotin(IV) moiety reacts with the phenolic form ofthese ligands. In the complexes with –OH and –COOH functions, the –COOH group is coordinated to the organotin(IV) centres in amonodentate manner. The 119 Sn Mo¨ssbauer and the FT-IR studies suppor…

Towards Quantifying Non-Photosynthetic Vegetation for Agriculture Using Spaceborne Imaging Spectroscopy

2021

Non-photosynthetic vegetation (NPV) has been identified as priority variable in the context of new spaceborne imaging spectroscopy missions. In this study we provide a first attempt to quantify NPV biomass from these unprecedented data streams to be provided by multiple recently launched or planned instruments. A hybrid workflow is proposed including Gaussian process regression (GPR) trained over radiative transfer model (RTM) simulations and applying active learning strategies. A soybean field data set including two dates with NPV measurements on yellow and senescent (brown) plant organs was used for model validation, resulting in relative errors of 13.4%. This prototype retrieval model wa…

2021

Nitrogen (N) is one of the key nutrients supplied in agricultural production worldwide. Over-fertilization can have negative influences on the field and the regional level (e.g., agro-ecosystems). Remote sensing of the plant N of field crops presents a valuable tool for the monitoring of N flows in agro-ecosystems. Available data for validation of satellite-based remote sensing of N is scarce. Therefore, in this study, field spectrometer measurements were used to simulate data of the Sentinel-2 (S2) satellites developed for vegetation monitoring by the ESA. The prediction performance of normalized ratio indices (NRIs), random forest regression (RFR) and Gaussian processes regression (GPR) f…