scholarly journals A Complementary and Revised View on the N-Acylation of Chitosan with Hexanoyl Chloride

Marine Drugs ◽  
2021 ◽  
Vol 19 (7) ◽  
pp. 385
Author(s):  
Berthold Reis ◽  
Niklas Gerlach ◽  
Christine Steinbach ◽  
Karina Haro Carrasco ◽  
Marina Oelmann ◽  
...  
Keyword(s):  
Potentiometric Titration ◽  
1H Nmr ◽  
Accurate Method ◽  
Strong Impact ◽  
Ph Variation ◽  
Accuracy And Precision ◽  
Low Molecular Weight Chitosan ◽  
The Impact ◽  
Reaction Media

The modification of the biobased polymer chitosan is a broad and widely studied field. Herein, an insight into the hydrophobization of low-molecular-weight chitosan by substitution of amino functionalities with hexanoyl chloride is reported. Thereby, the influence of the pH of the reaction media was investigated. Further, methods for the determination of the degree of substitution based on 1H-NMR, FTIR, and potentiometric titration were compared and discussed regarding their accuracy and precision. 1H-NMR was the most accurate method, while FTIR and the potentiometric titration, though precise and reproducible, underlie the influence of complete protonation and solubility issues. Additionally, the impact of the pH variation during the synthesis on the properties of the samples was investigated by Cd2+ sorption experiments. The adjusted pH values during the synthesis and, therefore, the obtained degrees of substitution possessed a strong impact on the adsorption properties of the final material.

Innovations in human resources management: impact on economic growth

2021 ◽  
Vol 5 (3) ◽  
pp. 53-65
Author(s):  
Monika Danova ◽  
Ivana Kravcakova Vozarova ◽  
Elena Sira
Keyword(s):  
Economic Growth ◽  
Human Capital ◽  
Economic Performance ◽  
Human Resources Management ◽  
Precise Determination ◽  
P Value ◽  
Strong Impact ◽  
Literary Sources ◽  
The Impact

In recent years, human capital has become increasingly emphasized as a factor of economic growth. Managing human capital could stimulate the whole economy to better performance in competitiveness. Although these indicators include several variables, there is no precise determination of which indicator mostly affects the country's economic growth. This paper summarizes the knowledge and approaches of several authors in the field of economic growth, knowledge economy, competitiveness, innovations and individual elements affecting these areas. It outlines the findings and provides some insight into the impact of individual factors on economic growth across recent studies. The main goal is to obtain information about the impact of education, its support, and its influence on economic performance on the example of empirical data documenting the qualitative parameters of the workforce. The use of selected indicators indicated their impact on the change in economic performance. The partial objective is to identify an indicator or set of indicators that could express the impact of human capital on economic growth. The study involved research methods such as analyzes, statistical methods such as correlation and p-value, and prediction for the next period based on past developments. The research object is the V4 countries – the Czech Republic, Slovakia, Hungary, and Poland. The findings pointed to the strong impact of the analyzed factors on economic growth. Besides, they showed which of the known ways to increase the efficiency of the labor factor were actually or little used in the sample countries. Undoubtedly, there is also an indicative and interesting comparison within a group or with other economies at a comparable economic and social development level. Finally, improvements to the current situation were proposed. The systematization of literary sources and approaches to economic growth helps identify possible proposals for improving competitiveness in the future, using innovative approaches.

scholarly journals Asteroseismic potential of CHEOPS

2018 ◽  
Vol 620 ◽  
pp. A203 ◽  
Author(s):  
A. Moya ◽  
S. Barceló Forteza ◽  
A. Bonfanti ◽  
S. J. A. J. Salmon ◽  
V. Van Grootel ◽  
...  
Keyword(s):  
Time Series ◽  
Main Sequence ◽  
Uncertainty Reduction ◽  
Light Curves ◽  
Accuracy And Precision ◽  
Mass Uncertainty ◽  
The Impact ◽  
Host Stars

Context. Asteroseismology has been impressively boosted during the last decade mainly thanks to space missions such as Kepler/K2 and CoRoT. This has a large impact, in particular, in exoplanetary sciences since the accurate characterization of the exoplanets is convoluted in most cases with the characterization of their hosting star. In the decade before the expected launch of the ESA mission PLATO 2.0, only two important missions will provide short-cadence high-precision photometric time-series: NASA–TESS and ESA–CHEOPS missions, both having high capabilities for exoplanetary sciences. Aims. In this work we want to explore the asteroseismic potential of CHEOPS time-series. Methods. Following the works estimating the asteroseismic potential of Kepler and TESS, we have analysed the probability of detecting solar-like pulsations using CHEOPS light-curves. Since CHEOPS will collect runs with observational times from hours up to a few days, we have analysed the accuracy and precision we can obtain for the estimation of νmax. This is the only asteroseismic observable we can recover using CHEOPS observations. Finally, we have analysed the impact of knowing νmax in the characterization of exoplanet host stars. Results. Using CHEOPS light-curves with the expected observational times we can determine νmax for massive G and F-type stars from late main sequence (MS) on, and for F, G, and K-type stars from post-main sequence on with an uncertainty lower than a 5%. For magnitudes V <  12 and observational times from eight hours up to two days, the HR zone of potential detectability changes. The determination of νmax leads to an internal age uncertainty reduction in the characterization of exoplanet host stars from 52% to 38%; mass uncertainty reduction from 2.1% to 1.8%; radius uncertainty reduction from 1.8% to 1.6%; density uncertainty reduction from 5.6% to 4.7%, in our best scenarios.

scholarly journals Application of Hyphenated Techniques in Speciation Analysis of Arsenic, Antimony, and Thallium

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Rajmund Michalski ◽  
Sebastian Szopa ◽  
Magdalena Jabłońska ◽  
Aleksandra Łyko
Keyword(s):  
Speciation Analysis ◽  
Clinical Analysis ◽  
Pharmaceutical Products ◽  
Strong Impact ◽  
Hyphenated Techniques ◽  
Unique Role ◽  
Species Analysis ◽  
Control Research ◽  
The Impact

Due to the fact that metals and metalloids have a strong impact on the environment, the methods of their determination and speciation have received special attention in recent years. Arsenic, antimony, and thallium are important examples of such toxic elements. Their speciation is especially important in the environmental and biomedical fields because of their toxicity, bioavailability, and reactivity. Recently, speciation analytics has been playing a unique role in the studies of biogeochemical cycles of chemical compounds, determination of toxicity and ecotoxicity of selected elements, quality control of food products, control of medicines and pharmaceutical products, technological process control, research on the impact of technological installation on the environment, examination of occupational exposure, and clinical analysis. Conventional methods are usually labor intensive, time consuming, and susceptible to interferences. The hyphenated techniques, in which separation method is coupled with multidimensional detectors, have become useful alternatives. The main advantages of those techniques consist in extremely low detection and quantification limits, insignificant interference, influence as well as high precision and repeatability of the determinations. In view of their importance, the present work overviews and discusses different hyphenated techniques used for arsenic, antimony, and thallium species analysis, in different clinical, environmental and food matrices.

Assessment of Measuring Errors in Strain Fields Obtained via DIC on Planar Sheet Metal Specimens with a Non-Perpendicular Camera Alignment

2011 ◽  
Vol 70 ◽  
pp. 165-170 ◽  
Author(s):  
Pascal Lava ◽  
Sam Coppieters ◽  
Yue Qi Wang ◽  
Paul van Houtte ◽  
Dimitri Debruyne
Keyword(s):  
Sheet Metal ◽  
Biaxial Loading ◽  
Image Plane ◽  
Displacement Fields ◽  
Strain Fields ◽  
Accuracy And Precision ◽  
Camera View ◽  
Plane Displacement ◽  
The Impact

The determination of strain fields based on displacement components obtained via 2D-DIC is subject to several errors that originate from various sources. In this contribution, we study the impact of a non-perpendicular camera alignment to a planar sheet metal specimen’s surface subject to biaxial loading conditions. The errors are estimated in a numerical experiment. To this purpose, deformed images - that were obtained by imposing finite element (FE) displacement fields on an undeformed image - are numerically rotated for various Euler angles. It is shown that a 3D-DIC stereo configuration induces a substantial compensation for the introduced image-plane displacement gradients. However, higher strain accuracy and precision are obtained - up to the level of a perfect perpendicular alignment - in a proposed ”rectified” 2D-DIC setup. This compensating technique gains benefit from both 2D-DIC (single camera view, basic amount of correlation runs, no cross-camera matching nor triangulation) and 3D-DIC (oblique angle compensation).

scholarly journals Thorough Multianalytical Characterization and Quantification of Micro- and Nanoplastics from Bracciano Lake’s Sediments

2020 ◽  
Vol 12 (3) ◽  
pp. 878 ◽  
Author(s):  
Andrea Corti ◽  
Virginia Vinciguerra ◽  
Valentina Iannilli ◽  
Loris Pietrelli ◽  
Antonella Manariti ◽  
...  
Keyword(s):  
1H Nmr ◽  
Average Molecular Weight ◽  
Sampling Site ◽  
Chemical Characterization ◽  
Analytical Techniques ◽  
Proton Nuclear Magnetic Resonance ◽  
Volcanic Lake ◽  
Chromatographic Detection ◽  
The Impact

Lake basins can behave as accumulators of microplastics released in wastewaters as such or resulting from degradation of larger items before and/or during their journey toward the marine environment as a final sink. A novel multianalytical approach was adopted for the detection and quantification of microplastics with size < 2 mm in the sediments of the volcanic lake of Bracciano, Italy. Simple analytical techniques such as solvent extraction/fractionation (for polyolefins and polystyrene) or depolymerization (for polyethylene terephthalate, PET), along with chromatographic detection (SEC and HPLC), allowed quantitative and qualitative determination of the main synthetic polymer contaminants. In particular, PET microplastic concentrations of 0.8–36 ppm were found, with variability related to the sampling site (exposure to incoming winds and wave action). Proton Nuclear Magnetic Resonance (1H-NMR) and Attenuated Total Reflectance Fourier Transformed InfraRed (ATR-FTIR spectroscopic investigations supported the identification and chemical characterization of plastic fragments and polymer extracts. The average molecular weight of solvent extractable polymers was evaluated from 2D 1H-NMR diffusion ordered spectroscopy (DOSY) experiments. The proposed, easily accessible multianalytical approach can be considered as a useful tool for improving our knowledge on the nature and the concentration of microplastics in sediments, giving insights on the impact of human activities on the health status of aquatic ecosystems.

scholarly journals Neutron Star Properties: Quantifying the Effect of the Crust–Core Matching Procedure

Universe ◽  
2020 ◽  
Vol 6 (11) ◽  
pp. 220
Author(s):  
Márcio Ferreira ◽  
Constança Providência
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Nuclear Matter ◽  
Strong Impact ◽  
The Core ◽  
Meta Modeling ◽  
Low Mass ◽  
Matching Procedure ◽  
The Impact

The impact of the equation of state (EoS) crust-core matching procedure on neutron star (NS) properties is analyzed within a meta-modeling approach. Using a Taylor expansion to parametrize the core equation of state (EoS) and the SLy4 crust EoS, we create two distinct EoS datasets employing two matching procedures. Each EoS describes cold NS matter in a β equilibrium that is thermodynamically stable and causal. It is shown that the crust-core matching procedure affects not only the crust-core transition but also the nuclear matter parameter space of the core EoS, and thus the most probable nuclear matter properties. An uncertainty of as much as 5% (8%) on the determination of low mass NS radii (tidal deformability) is attributed to the complete matching procedure, including the effect on core EoS. By restricting the analysis, imposing that the same set of core EoS is retained in both matching procedures, the uncertainty on the NS radius drops to 3.5% and below 1.5% for 1.9M⊙. Moreover, under these conditions, the crust-core matching procedure has a strong impact on the Love number k2, of almost 20% for 1.0M⊙ stars and 7% for 1.9M⊙ stars, but it shows a very small impact on the tidal deformability Λ, below 1%.

scholarly journals Quantitative determination of the new substance 7-(4-fluorobenzyl)-3-thioxo-2,3-dihydro[1,2,4]triazolo[4,3-a]pyrazin-8(7H)-one as a potential pharmaceutical agent

Chemija ◽  
2021 ◽  
Vol 32 (1) ◽  
Author(s):  
Krystyna Netosova ◽  
Oksana Zavada ◽  
Anna Materiienko ◽  
Iryna Zhuravel ◽  
Serhii Baiurka
Keyword(s):  
Quantitative Determination ◽  
Potentiometric Titration ◽  
Acceptance Criteria ◽  
Quantification Method ◽  
Pharmaceutical Agent ◽  
Accuracy And Precision

The article presents results of studies on the development of a quantification method for a substance 7-(4-fluorobenzyl)-3-thioxo-2,3-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-8(7H)-one using the method of nonaqueous potentiometric titration. Validation of the developed method has been carried out confirming the following characteristics: linearity, accuracy and precision that match the acceptance criteria for these measures.

Clean Room and Microwave Digestion Techniques: Improvement in Detection Limits for Aluminum Determination by GF-AAS

1988 ◽  
Vol 42 (7) ◽  
pp. 1302-1306 ◽  
Author(s):  
E. M. Skelly ◽  
F. T. Distefano
Keyword(s):  
Graphite Furnace ◽  
Microwave Digestion ◽  
Accurate Method ◽  
Graphite Tube ◽  
Clean Room ◽  
Accuracy And Precision ◽  
Graphite Furnace Atomic Absorption ◽  
Gf Aas ◽  
Microwave Digestion System

A rapid, precise, and accurate method for the determination of aluminum in part-per-billion concentrations in biological materials using graphite-furnace atomic absorption spectroscopy has been developed. In order that the necessary accuracy and precision for the analysis of aluminum in bone and brain tissue could be obtained, reduction of laboratory environmental contributions to the aluminum blank was required. Use of a closed-vessel microwave digestion system and a clean room for sample preparation accomplished this goal by reducing Al concentrations in the digestion blanks from 10 ppb to 1 ppb. Digestion time was decreased from many hours to several minutes, and the amount of acid required for digestion was reduced by 70%. Using less nitric acid improved precision in the analyzed solutions by significantly extending the lifetime and consistency in performance of the graphite tube atomizer.

scholarly journals Cosmogenic 3He in terrestrial rocks: a review

2021 ◽  
Author(s):  
Pierre-Henri BLARD
Keyword(s):  
Production Rate ◽  
Noble Gas ◽  
Size Fraction ◽  
Cosmogenic Nuclides ◽  
Absolute Calibration ◽  
Calibration Data ◽  
Production Rates ◽  
Accuracy And Precision ◽  
The Impact

This review article summarizes the state of the art of cosmogenic 3He (3Hec), with a focus on the most efficient methods for measuring this cosmogenic noble gas in terrestrial samples. After briefly reviewing the scientific applications and production pathways of cosmogenic 3He, I summarize the most important theoretical and practical aspects of 3He analyses and describe the best strategies for correcting for non-cosmogenic 3He components in minerals. I also review our knowledge of 3Hec production rates and explore potential new applications for future studies.Our ability to accurately and precisely measure cosmogenic 3He is mainly constrained by the level of the non-cosmogenic 3He background (i.e., magmatic, radiogenic, nucleogenic, and atmospheric 3He), and thus by the geological characteristics of the samples. Constructing 3He vs. 4He isochrons by analyzing several aliquots from the same sample constitutes a useful and overlooked method that is advantageous because it obviates the often-complicated step of vacuum crushing. This method also allows the direct and joint determination of cosmogenic 3He and the magmatic 3He/4He ratio. I perform numerical modeling to explore the impact of the non-cosmogenic 3He components on the final uncertainties and detection limits of 3He dating. Reducing the magmatic component by selecting phenocrysts in the 100–500 m size fraction improves the precision of cosmogenic 3He analyses. Moreover, it is important to measure U, Th, and Li concentrations in the analyzed minerals and their host rocks to ensure proper corrections for radiogenic 4He and nucleogenic 3He, improving both the accuracy and precision of the method.After summarizing the most important aspects of 3He analytical techniques, including the best 3Hec extraction techniques and the key parameters of noble gas mass spectrometry that result in accurate and precise helium isotopic measurements, I also review 3Hec production rates and their spatial variability. The global database of absolute calibration sites yields a world-wide average 3Hec production rate in olivine and pyroxene of 124 ± 11 at g−1 yr−1 using the LSD scaling and the online CREp calculator (https://crep.otelo.univ-lorraine.fr/#/). Cross-calibrations against 10Be indicate that the ratio of the production rate of 3Hec in olivine/pyroxene to that of 10Be in quartz is 33 ± 2 and increases by less than 7% between sea level and 5,000 m elevation. This important observation demonstrates that 3He in olivine/pyroxene and 10Be in quartz can be considered as synchronized chronometers. However, 3Hec/10Be cross-calibrations based on 3Hec in accessory minerals (zircon, garnet, kyanite, apatite) yield unexpectedly high 3He/10Be production ratios of 40–60 above 3,000 m elevation. As the capture of cosmogenic thermal neutrons by 6Li is unlikely to explain this excess, I discuss other plausible mechanisms that should be explored, such as 3Hec inherited from previous exposure episodes, unrecognized specific reaction pathways, or the impact of snow cover. New cross-calibration data obtained by measuring 3Hec against other cosmogenic nuclides in different settings will advance our understanding of cosmogenic nuclide production rates and improve the accuracy and precision of applications relying on cosmogenic 3He. Other improvements could extend the applicability of the 3He geoscientific toolbox; for example, coupling 3He with radioactive cosmogenic nuclides (10Be, 36Cl, 53Mn) will allow paleoaltimetry or the determination of burial ages or paleo-depths in intermediate and mafic terrains.

The impact of contamination from a municipal solid waste landfill (Zagreb, Croatia) on underlying soil

1998 ◽  
Vol 37 (8) ◽  
pp. 203-210 ◽  
Author(s):  
Marijan Ahel ◽  
Nevenka Mikac ◽  
Bozena Cosovic ◽  
Esad Prohic ◽  
Vesna Soukup
Keyword(s):  
Solid Waste ◽  
Microbial Transformation ◽  
Hydrological Regime ◽  
Total Content ◽  
Strong Impact ◽  
Aquifer Sediments ◽  
The Impact ◽  
The City ◽  
Underlying Soil

The present study was conducted on the main landfill of the city of Zagreb which contains about 5 million tons of waste disposed of directly onto highly permeable alluvial sediments. The investigations were aimed at assessing the impact of contamination from the landfill on underlying soil and comprised the determination of a broad spectrum of inorganic and organic constituents in the samples (size fractions &lt;2 mm) of solid waste, soil and aquifer sediments. Both the total content of various contaminants as well as their part which is readily leachable with water were determined in the examined samples. Compound classes identified in the landfill can be classified into the two main categories: (1) markers of biological waste and of its microbial transformation (ammonia, dissolved organic carbon, short-chain aliphatic acids, phenols, derivatives of abietic acid) and (2) markers of anthropogenic waste (toxic metals, hydrocarbons, chlorinated hydrocarbons, surfactant-derived compounds, phthalates, pharmaceutical chemicals). The complex assemblages of contaminants were shown to change dramatically during the transport from the solid waste through unsaturated zone of the soil to aquifer sediments. It was shown that, in addition to the vertical infiltration of leachate from the solid waste, the hydrological regime of groundwater has also a strong impact on the contaminant distribution in soils below the landfill.

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