scholarly journals The Calibration Home Base for Imaging Spectrometers

2016 ◽  
Vol 2 ◽  
Author(s):  
Johannes Felix Simon Brachmann ◽  
Andreas Baumgartner ◽  
Peter Gege
Keyword(s):  
Wavelength Range ◽  
Stray Light ◽  
Third Party ◽  
Home Base ◽  
Geometric Calibration ◽  
Wide Range ◽  
Along Track ◽  
Near Future

The Calibration Home Base (CHB) is an optical laboratory designed for the calibration of imaging spectrometers for the VNIR/SWIR wavelength range. Radiometric, spectral and geometric calibration as well as the characterization of sensor signal dependency on polarization are realized in a precise and highly automated fashion. This allows to carry out a wide range of time consuming measurements in an ecient way. The implementation of ISO 9001 standards in all procedures ensures a traceable quality of results. Spectral measurements in the wavelength range 380–1000 nm are performed to a wavelength uncertainty of +- 0.1 nm, while an uncertainty of +-0.2 nm is reached in the wavelength range 1000 – 2500 nm. Geometric measurements are performed at increments of 1.7 µrad across track and 7.6 µrad along track. Radiometric measurements reach an absolute uncertainty of +-3% (k=1). Sensor artifacts, such as caused by stray light will be characterizable and correctable in the near future. For now, the CHB is suitable for the characterization of pushbroom sensors, spectrometers and cameras. However, it is planned to extend the CHBs capabilities in the near future such that snapshot hyperspectral imagers can be characterized as well. The calibration services of the CHB are open to third party customers from research institutes as well as industry.

scholarly journals Effects of gas–wall interactions on measurements of semivolatile compounds and small polar molecules

2019 ◽  
Vol 12 (6) ◽  
pp. 3137-3149 ◽  
Author(s):  
Xiaoxi Liu ◽  
Benjamin Deming ◽  
Demetrios Pagonis ◽  
Douglas A. Day ◽  
Brett B. Palm ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Transmission Efficiency ◽  
Polar Molecules ◽  
Ionization Mass ◽  
Atmospheric Measurements ◽  
Wide Range ◽  
Teflon Tubing ◽  
Gas Interactions

Abstract. Recent work has quantified the delay times in measurements of volatile organic compounds (VOCs) caused by the partitioning between the gas phase and the surfaces of the inlet tubing and instrument itself. In this study we quantify wall partitioning effects on time responses and transmission of multifunctional, semivolatile, and intermediate-volatility organic compounds (S/IVOCs) with saturation concentrations (C∗) between 100 and 104 µg m−3. The instrument delays of several chemical ionization mass spectrometer (CIMS) instruments increase with decreasing C∗, ranging from seconds to tens of minutes, except for the NO3- CIMS where it is always on the order of seconds. Six different tubing materials were tested. Teflon, including PFA, FEP, and conductive PFA, performs better than metals and Nafion in terms of both delay time and transmission efficiency. Analogous to instrument responses, tubing delays increase as C∗ decreases, from less than a minute to >100 min. The delays caused by Teflon tubing vs. C∗ can be modeled using the simple chromatography model of Pagonis et al. (2017). The model can be used to estimate the equivalent absorbing mass concentration (Cw) of each material, and to estimate delays under different flow rates and tubing dimensions. We also include time delay measurements from a series of small polar organic and inorganic analytes in PFA tubing measured by CIMS. Small polar molecules behave differently than larger organic ones, with their delays being predicted by their Henry's law constants instead of their C∗, suggesting the dominance of partitioning to small amounts of water on sampling surfaces as a result of their polarity and acidity properties. PFA tubing has the best performance for gas-only sampling, while conductive PFA appears very promising for sampling S/IVOCs and particles simultaneously. The observed delays and low transmission both affect the quality of gas quantification, especially when no direct calibration is available. Improvements in sampling and instrument response are needed for fast atmospheric measurements of a wide range of S/IVOCs (e.g., by aircraft or for eddy covariance). These methods and results are also useful for more general characterization of surface–gas interactions.

scholarly journals Effects of Gas-Wall Interactions on Measurements of Semivolatile Compounds and Small Polar Molecules

2019 ◽  
Author(s):  
Xiaoxi Liu ◽  
Benjamin Deming ◽  
Demetrios Pagonis ◽  
Douglas A. Day ◽  
Brett B. Palm ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Transmission Efficiency ◽  
Polar Molecules ◽  
Ionization Mass ◽  
Atmospheric Measurements ◽  
Wide Range ◽  
Teflon Tubing ◽  
Gas Interactions

Abstract. Recent work has quantified the delay times in measurements of volatile organic compounds (VOCs) caused by the partitioning between the gas phase and the surfaces of the inlet tubing and instrument itself. In this study we quantify wall partitioning effects on time responses and transmission of multi-functional, semivolatile and intermediate-volatility organic compounds (S/IVOCs) with saturation concentrations (C*) between 100 and 104 µg m−3. The instrument delays of several chemical ionization mass spectrometer (CIMS) instruments increase with decreasing C*, ranging from seconds to tens of minutes, except for the NO3−-CIMS where it is always on the order of seconds. Six different tubing materials were tested. Teflon, including PFA, FEP, and conductive PFA, performs better than metals and Nafion in terms of both delay time and transmission efficiency. Analogous to instrument responses, tubing delays increase as C* decreases, from less than a minute to > 100 min. The delays caused by Teflon tubing vs. C* can be modeled using the simple chromatography model of Pagonis et al. (2017). The model can be used to estimate the equivalent absorbing mass concentration (Cw) of each material, and to estimate delays under different flow rates and tubing dimensions. We also include time delay measurements from a series of small polar organic and inorganic analytes in PFA tubing measured by CIMS. Small polar molecules behave differently than larger organic ones, with their delays being predicted by their Henry’s law constants instead of their C*, suggesting the dominance of partitioning to small amounts of water on sampling surfaces as a result of their polarity and acidity properties. PFA tubing has the best performance for gas-only sampling, while conductive PFA appears very promising for sampling S/IVOCs and particles simultaneously. The observed delays and low transmission both affect the quality of gas quantification, especially when no direct calibration is available. Improvements in sampling and instrument response are needed for fast atmospheric measurements of a wide range of S/IVOCs (e.g., by aircraft or for eddy covariance). These methods and results are also useful for more general characterization of surface/gas interactions.

scholarly journals Interface Refinement of Low-to-Medium Resolution Cryo-EM Complexes using HADDOCK2.4

2021 ◽  
Author(s):  
Tim Neijenhuis ◽  
Siri C. van Keulen ◽  
Alexandre M.J.J. Bonvin
Keyword(s):  
Protein Complexes ◽  
Protein Assemblies ◽  
Cellular Processes ◽  
Protein Interfaces ◽  
Density Maps ◽  
Medium Resolution ◽  
Wide Range ◽  
Multimeric Protein

A wide range of cellular processes require the formation of multimeric protein complexes. The rise of cryo-electron microscopy (cryo-EM) has enabled the structural characterization of these protein assemblies. The produced density maps can, however, still suffer from limited resolution, impeding the process of resolving structures at atomic resolution. In order to solve this issue, monomers can be fitted into low-to-medium resolution maps. Unfortunately, the produced models frequently contain atomic clashes at the protein-protein interfaces (PPIs) as intermolecular interactions are typically not considered during monomer fitting. Here, we present a refinement approach based on HADDOCK2.4 to remove intermolecular clashes and optimize PPIs. A dataset of 14 cryo-EM complexes was used to test eight protocols. The best performing protocol, consisting of a semi-flexible simulated annealing refinement with restraints on the centroids of the monomers, was able to decrease intermolecular atomic clashes by 98% without significantly deteriorating the quality of the cryo-EM density fit.

scholarly journals Third-party Annotations: Linking PlutoF platform and the ELIXIR Contextual Data ClearingHouse for the reporting of source material annotation gaps and inaccuracies

2021 ◽  
Vol 5 ◽  
Author(s):  
Kessy Abarenkov ◽  
Allan Zirk ◽  
Kadri Põldmaa ◽  
Timo Piirmann ◽  
Raivo Pöhönen ◽  
...  
Keyword(s):  
Data Management ◽  
Dna Sequence ◽  
Dna Sequences ◽  
Third Party ◽  
Web Interface ◽  
Material Source ◽  
Contextual Data ◽  
Management Platform ◽  
Wide Range

Third-party annotations are a valuable resource to improve the quality of public DNA sequences. For example, sequences in International Nucleotide Sequence Databases Collaboration (INSDC) often lack important features like taxon interactions, species level identification, information associated with habitat, locality, country, coordinates, etc. Therefore, initiatives to mine additional information from publications and link to the public DNA sequences have become common practice (e.g. Tedersoo et al. 2011, Nilsson et al. 2014, Groom et al. 2021). However, third-party annotations have their own specific challenges. For example, annotations can be inaccurate and therefore must be open for permanent data management. Further, every DNA sequence (except sequences from type material) can carry different species names, which must be databased as equal scientific hypotheses. PlutoF platform provides such data management services for third-party annotations. PlutoF is an online data management platform and computing service provider for biology and related disciplines. Registered users can enter and manage a wide range of data, e.g., taxon occurrences, metabarcoding data, taxon classifications, traits, and lab data. It also features an annotation module where third-party annotations (on material source, geolocation and habitat, taxonomic identifications, interacting taxa, etc.) can be added to any collection specimen, living culture or DNA sequence record. The UNITE Community is using these services to annotate and improve the quality of INSDC rDNA Internal Transcribed Spacer (ITS) sequence datasets. The National Center for Biotechnology Information (NCBI) is linking its ITS sequences with their annotations in PlutoF. However, there is still missing an automated solution for linking annotations in PlutoF with any sequence and sample record stored in INSDC databases. One of the ambitions of the BiCIKL Project is to solve this through operating the ELIXIR Contextual Data ClearingHouse (CDCH). CDCH offers a light and simple RESTful Application Programming Interface (API) to enable extension, correction and improvement of publicly available annotations on sample and sequence records available in ELIXIR data resources. It facilitates feeding improved or corrected annotations from databases (such as secondary databases, e.g., PlutoF, which consume and curate data from repositories) back to primary repositories (databases of the three INSDC collaborative partners). In the Biodiversity Community Integrated Knowledge Library (BiCIKL) Project, the University of Tartu Natural History Museum is leading the task of linking the two components—the web interface provided by the PlutoF platform and CDCH APIs—to allow user-friendly and effortless reporting of errors and gaps in sequenced material source annotations. The API and web interface will be promoted to those communities (such as taxonomists, those abstracting from the literature, and those already using the community curated data) with the appropriate knowledge and tools who will be encouraged to report their enhanced annotations back to primary repositories.

The characterization of volatile molecular substances

1993 ◽  
Vol 443 (1918) ◽  
pp. 313-332 ◽  
Keyword(s):  
Subjective Evaluation ◽  
Sensor Arrays ◽  
Intrinsic Property ◽  
Wide Range ◽  
The Laplace Transform ◽  
Molecular Substances ◽  
Definition Of ◽  
Enclosed Space

Diffusion for gaseous sources comprising more than one type of substance is examined to show how relative concentrations change with time and distance. The large variations which are predicted make nonsense of the popular assumption that odour or smell is an intrinsic property of the source material. However, some characterization of volatile chemical substances is needed. It is shown that this is possible by creating a uniform and stable atmosphere after the relapse of sufficient time by introducing the gas mixture into an enclosed space. In this investigation the situation is analysed for a spherical enclosure using Fourier analysis techniques for the long timescale behaviour and the Laplace transform for the short timescale solution. The measurement of odours via the response of sensor arrays within a spherical enclosure is considered and a proposal is made for utilizing such an enclosure in a definition of volatile molecular substances (analogous to biological ‘smell’). The conditions for optimum compatibility between an array of sensors and a set of calibrands are discussed and the practical means of effecting such measurements are considered in relation to known types of sensor. It is concluded that the quality of volatile molecular substances is definable and measurable down to very low gas concentrations in air: probably below 10 parts per billion for a wide range of gas mixtures unconstrained by such limitations associated with a biological nose such as toxicity, temperature and subjective evaluation.

Emission and Laser-Induced Fluorescence Spectroscopy of Laser-Ablated Titanium Plume

1999 ◽  
Author(s):  
Schubert S. Chu ◽  
Costas P. Grigoropoulos
Keyword(s):  
Time Of Flight ◽  
Laser Induced Fluorescence ◽  
Spectroscopic Techniques ◽  
Wide Range ◽  
Optical Time ◽  
Background Gas ◽  
Spectrally Resolved ◽  
Deposited Film

Abstract Pulsed laser deposition (PLD) of thin films has evolved into a well-recognized technique for a wide range of materials and in a variety of devices. There is great interest in the energy characterization of the ablated plume because this is a key parameter in determining the quality of the deposited film. Spectroscopic techniques, such as optical time-of-flight (TOF,) emission spectroscopy, and laser-induced-fluorescence (LIF) are excellent methods for this purpose since they offer temporal and spatial resolution as well as the capability of distinguishing different species. The effects of laser fluence and background gas pressure on the kinetic energies of the ablated species were found by the optical time-of flight technique and by emission imaging. Furthermore, laser-induced-fluorescence was employed for spectrally resolved imaging. The results provide additional data on the kinetic energy and the distribution of neutral titanium. The axial velocity of neutral titanium was found to be as high as 2 × 104 m/s. The distribution of species within the plume was also determined.

scholarly journals Characterization of ‘Castellana’ Virgin Olive Oils with Regard to Olive Ripening

2018 ◽  
Vol 28 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Carmen Mena ◽  
Alejandra Z. González ◽  
Raúl Olivero-David ◽  
María Ángeles Pérez-Jiménez
Keyword(s):  
Olive Oil ◽  
Virgin Olive Oil ◽  
Quality Parameters ◽  
Virgin Olive Oils ◽  
Olive Oils ◽  
Wide Range ◽  
Sensorial Quality ◽  
Olive Ripening

The production of high-quality virgin olive oil from traditional olive (Olea europaea L.) varieties with peculiar and differential characteristics is of great interest for the olive oil market. ‘Castellana’ is an autochthonous variety mainly located in the center of Spain. The aims of this study were 1) the characterization of ‘Castellana’ virgin olive oils and 2) the evaluation of the influence of fruit ripening degree on the oil quality to establish an optimum harvest time for ‘Castellana’ olives. A wide range of physicochemical and sensorial quality parameters were assayed in oils produced at four harvest times during three crop seasons. ‘Castellana’ oils could be classified into the extra virgin category at all ripening degrees studied. This variety provides well-balanced oils from the sensorial point of view with an optimum chemical composition. Nevertheless, fruit maturation had a strong effect in various quality parameters, especially total phenol content, total tocopherol content, sensorial quality, and to a lesser extent in fatty acid composition. Loss of antioxidants and decrease in sensorial quality take place during olive ripening, reducing the nutritional, sensorial, and commercial quality of virgin olives oils as the harvest is delayed. Results suggest that the production of optimal extra virgin olive oil requires that ‘Castellana’ olives should be harvested from the middle of November to the middle of December, coinciding with a ripening index between 3.1 and 4.1. These results are of great importance to the olive oil industry for improving the quality of virgin olive oils produced from ‘Castellana’.

scholarly journals Virtual physiological human: training challenges

2010 ◽  
Vol 368 (1921) ◽  
pp. 2841-2851 ◽  
Author(s):  
Patricia V. Lawford ◽  
Andrew V. Narracott ◽  
Keith McCormack ◽  
Jesus Bisbal ◽  
Carlos Martin ◽  
...  
Keyword(s):  
Data Mining ◽  
Knowledge Discovery ◽  
Functional Imaging ◽  
Imaging Data ◽  
Database Development ◽  
Wide Range ◽  
Quantitative Changes ◽  
Near Future ◽  
Modelling Simulation

The virtual physiological human (VPH) initiative encompasses a wide range of activities, including structural and functional imaging, data mining, knowledge discovery tool and database development, biomedical modelling, simulation and visualization. The VPH community is developing from a multitude of relatively focused, but disparate, research endeavours into an integrated effort to bring together, develop and translate emerging technologies for application, from academia to industry and medicine. This process initially builds on the evolution of multi-disciplinary interactions and abilities, but addressing the challenges associated with the implementation of the VPH will require, in the very near future, a translation of quantitative changes into a new quality of highly trained multi-disciplinary personnel. Current strategies for undergraduate and on-the-job training may soon prove insufficient for this. The European Commission seventh framework VPH network of excellence is exploring this emerging need, and is developing a framework of novel training initiatives to address the predicted shortfall in suitably skilled VPH-aware professionals. This paper reports first steps in the implementation of a coherent VPH training portfolio.

The Test Method Research of Electric Light Sources Parameters and Detection of Uncertainty Evaluation

2011 ◽  
Vol 130-134 ◽  
pp. 4114-4117
Author(s):  
Xiao Ling Wang ◽  
Xue Yao Qian ◽  
Zhyingi Dai
Keyword(s):  
Test Method ◽  
Laboratory Measurement ◽  
Light Sources ◽  
Calibration Laboratory ◽  
Quality Of Results ◽  
Wide Range ◽  
Measurement Results ◽  
Important Basis

Characterization of measurement uncertainty as a measure of quality of results, and obtained in the metrology of a wide range of applications. At all levels of certified calibration laboratory measurement, measurement standards of the establishment of technical reports, or identification certificate issued by the calibration and so on, require a higher level in the measuring results are given to provide the corresponding uncertainty. Measuring the quality of the results of the measurement results is a measure of the credibility of an important basis. In this paper, through concrete examples and laboratory measurement of electrical parameters of the light source of the data obtained, the Evaluation of Uncertainty.

scholarly journals Experience of short term earthquake precursors with VLF–VHF electromagnetic emissions

2003 ◽  
Vol 3 (3/4) ◽  
pp. 217-228 ◽  
Author(s):  
K. Eftaxias ◽  
P. Kapiris ◽  
J. Polygiannakis ◽  
A. Peratzakis ◽  
J. Kopanas ◽  
...  
Keyword(s):  
Earthquake Prediction ◽  
Large Scale ◽  
Field Measurements ◽  
Short Term ◽  
Wide Range ◽  
Electromagnetic Emissions ◽  
Electro Magnetic ◽  
Focal Zone

Abstract. Electromagnetic anomalies (EMA) covering a wide range of frequencies from ULF, VLF up to VHF have been observed before recent destructive earthquakes in continental Greece. We show that the features of these signals are possibly correlated with the fault model characteristics of the associated earthquake and with the degree of geotectonic heterogeneity within the focal zone. The time evolution of these electromagnetic sequences reveals striking similarities to that observed in laboratory acoustic and electromagnetic emissions during different stages of failure preparation process in rocks. If we consider that the same dynamics governs the large-scale earthquakes and the microscopic scale sample rheological structure, the results of this analysis suggest that the recorded EMA might reflect the nucleation phase of the associated impending earthquake. We focus on the rise of the statistical view of earthquakes. We find electro-magnetic fingerprints of an underlying critical mechanism. Finally, we conclude that it is useful to combine ULF and VLF-VHF field measurements in an attempt to enhance the understanding of the physics behind these observations and thus to improve the quality of earthquake prediction. Further, the identification of an EMA as a seismogenic one supports the characterization of a sequence of shocks as foreshocks at the time they occur, further helping the earthquake prediction effort.

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