scholarly journals A Method for Characterizing the Chemical Heterogeneity of Comb-Copolymers and Its Dependence on Synthesis Routes

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1921
Author(s):  
Stefanie Anne Weckwerth ◽  
Wolfgang Radke ◽  
Robert J. Flatt
Keyword(s):  
Molecular Size ◽  
Industrial Scale ◽  
Chemical Heterogeneity ◽  
Test Case ◽  
Molecular Heterogeneity ◽  
Uv Detector ◽  
Good Test ◽  
Wide Range ◽  
Synthesis Routes ◽  
Comb Copolymer

The heterogeneity in chemical structure of polymers is difficult to characterize and consequently remains an often-overlooked factor in mechanistic studies of functional polymers, as well as in their industrial scale optimization. In this study, we present a method to characterize chemical heterogeneity and apply it to illustrate how it can be affected differently in different synthesis routes. The polymers used are comb-copolymer dispersants used in particulate suspensions which are composed of a polycarboxylate backbone onto which PEG side chains are grafted. The largest use of these polymers concerns concrete, where they are referred to as poly(carboxylate ether) (PCE) superplasticizers and produced at a very large industrial scale. Apart from their practical relevance, PCEs provide a good test case for studying the means and benefits of characterizing chemical heterogeneity. Indeed, the simple addition of a UV detector to a traditional SEC setup with RI detection allowed us to monitor variations in the grafting ratio in dependence on the molecular size. We show that the synthesis pathway significantly impacts the chemical heterogeneity. The suggested method is versatile and can be adapted for a wide range of hydrophilic copolymers. Thus, we present a tool to comprehensively analyze the molecular heterogeneity of dispersants and give a deep insight into their chemical dispersity.

scholarly journals Flurbiprofen: A Study of the Behavior of the Scalemate by Chromatography, Sublimation, and NMR

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 543
Author(s):  
Magdalena Kwiatkowska ◽  
Alicja Wzorek ◽  
Anna Kolbus ◽  
Mariusz Urbaniak ◽  
Jianlin Han ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Preparative Thin Layer Chromatography ◽  
Transverse Relaxation Time ◽  
Size Exclusion ◽  
Test Case ◽  
Ionization Mass ◽  
Chiral Drugs ◽  
Good Test ◽  
Exclusion Chromatography ◽  
Medium Pressure Liquid Chromatography

2-(2-Fluoro-4-biphenyl) propionic acid (flurbiprofen), from the phenylalkanoic acid family of nonsteroidal anti-inflammatory drugs (NSAID’s), is currently on the pharmaceutical market as a racemate. This racemic compound was tested for its propensity to undergo the self-disproportionation of enantiomers (SDE) phenomenon by various forms of chromatography (SDEvC), such as routine gravity-driven column chromatography, medium-pressure liquid chromatography (MPLC), preparative thin-layer chromatography (PTLC), and size-exclusion chromatography (SEC), as well as by sublimation (SDEvS). Furthermore, examination by nuclear magnetic resonance (NMR) in various solvents found that flurbiprofen exhibited the phenomenon of self-induced diastereomeric anisochronism (SIDA). By measurement of the diffusion coefficient (D), the longitudinal relaxation time (T1), and the transverse relaxation time (T2) using NMR, as well as by electrospray ionization-mass spectrometry (ESI-MS) examinations, the preferred intermolecular association was found to be solvent dependent, e.g., heterochiral association was preferred in toluene, while homochiral association was preferred in more polar solvents. This study also attempted, unsuccessfully, to correlate the NMR measurements of flurbiprofen with chromatographic outcomes for the rationalization and prediction of chromatographic results based on NMR measurements. Because the intermolecular hydrogen bonding of the acid groups in flurbiprofen overwhelmingly predominates over other intermolecular interactions, flurbiprofen seemed to represent a good test case for this idea. The behavior of scalemic samples of flurbiprofen is important, as, although it is currently dispensed as a racemate, clinical applications of the R enantiomer have been investigated. SDEvC and SDEvS both have ramifications for the preparation, handling, and storage of enantioenriched flurbiprofen, and this concern applies to other chiral drugs as well.

scholarly journals Excitation-Dependent Fluorescence Quantum Yield for Freshwater Chromophoric Dissolved Organic Matter from Northern Russian Lakes

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Svetlana Patsaeva ◽  
Daria Khundzhua ◽  
Oleg A. Trubetskoj ◽  
Olga E. Trubetskaya
Keyword(s):  
Organic Matter ◽  
Quantum Yield ◽  
Dissolved Organic Matter ◽  
Fluorescence Quantum Yield ◽  
Molecular Size ◽  
Reversed Phase ◽  
Chromophoric Dissolved Organic Matter ◽  
Excitation Wavelength ◽  
Fluorescence Detector ◽  
Wide Range

Advanced fluorescence analysis within the wide range of excitation wavelengths from 230 to 510 nm accompanied with chromatography was used to study natural chromophoric dissolved organic matter (CDOM) from three freshwater Karelian lakes. The influence of excitation wavelength (λex) on fluorescence quantum yield and emission maximum position was determined. The CDOM fluorescence quantum yield has reached a minimum at λex∼270–280 nm and a maximum at λex∼340–360 nm. It was monotonously decreasing after 370 nm towards longer excitation wavelengths. Analytical reversed-phase high-performance liquid chromatography with multiwavelength fluorescence detector characterized distribution of fluorophores between hydrophilic/hydrophobic CDOM parts. This technique revealed “hidden” protein-like fluorophores for some CDOM fractions, in spite of the absence of protein-like fluorescence in the initial CDOM samples. The humic-like fluorescence was documented for all hydrophilic and hydrophobic CDOM chromatographic peaks, and its intensity was decreasing along with peaks’ hydrophobicity. On contrary, the protein-like fluorescence was found only in the hydrophobic peaks, and its intensity was increasing along with peaks’ hydrophobicity. This work provides new data on the CDOM optical properties consistent with the formation of supramolecular assemblies controlled by association of low-molecular size components. In addition, these data are very useful for understanding the CDOM function in the environment.

scholarly journals Functional Materials Produced On An Industrial Scale

2015 ◽  
Vol 36 (1) ◽  
pp. 19-30
Author(s):  
Justyna Barska ◽  
Sylwester Kłysz
Keyword(s):  
Smart Materials ◽  
Industrial Production ◽  
Functional Materials ◽  
Industrial Scale ◽  
Wide Range ◽  
Basic Characteristics

AbstractThe article presents a wide range of applications of functional materials and a scale of their current industrial production. These are the materials which have specific characteristics, thanks to which they became virtually indispensable in certain constructional solutions. Their basic characteristics, properties, methods of production and use as smart materials were described.

scholarly journals 14C Dating of an Israelite Biblical Site at Kuntillet Ajrud (Horvat Teman)

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 205-212 ◽  
Author(s):  
Zeev Meshel ◽  
Israel Carmi ◽  
Dror Segal
Keyword(s):  
Iron Age ◽  
Single Phase ◽  
Test Case ◽  
14C Dating ◽  
Good Test ◽  
Iron Age Ii

The Israelite site of Kuntillet Ajrud in northern Sinai contains unique drawings and inscriptions in ancient Hebrew and Phoenician. It is a single-phase site dated archaeologically to ca. 800 bce. We considered this site a good test case for comparing archaeological with 14C datings. The dates are in agreement, confirming that 14C dating is useful in dating Iron-Age II sites.

Agreement with overt and null arguments in Ingush

Linguistics ◽  
2018 ◽  
Vol 56 (4) ◽  
pp. 845-863 ◽  
Author(s):  
Johanna Nichols
Keyword(s):  
Test Case ◽  
Gender Agreement ◽  
Contrast Variation ◽  
Good Test ◽  
Complementary Distribution ◽  
Null Arguments ◽  
Plausible Hypothesis ◽  
Theoretical Issues

Abstract Ingush (Nakh-Daghestanian, Caucasus) offers a variety of contexts with contrast, variation, or speaker choice between agreement and non-agreement and between overt and null arguments, which provide speakers many opportunities to manipulate agreement and argument marking. Ingush discourse is therefore a good test case for the plausible hypothesis that agreement and overt arguments are in complementary distribution. I survey referential density in a corpus of about 5000 words and find no evidence of either straightforward complementarity or expected incidental effects of such complementarity, and some evidence going against it. Some additional, orthogonal distributions were evident, showing that the corpus is large enough to reveal discourse effects if they were present. Ingush agreement is in gender, not person, and there is an arbitrary and strictly lexical bifurcation of verbs into those that do and those that do not have gender agreement; these typological points raise comparative and theoretical issues of interest.

scholarly journals Plate Finite Element with Physical Shape Functions: Correctness of the Formulation

2017 ◽  
Vol 63 (3) ◽  
pp. 19-37
Author(s):  
W. Gilewski ◽  
M. Sitek
Keyword(s):  
Finite Element ◽  
Good Choice ◽  
Test Case ◽  
Element Formulation ◽  
Structural Elements ◽  
Shape Functions ◽  
Solution Convergence ◽  
Wide Range ◽  
Physical Shape ◽  
Moderately Thick Plates

Abstract The formulation of a plate finite element with so called ‘physical’ shape functions is revisited. The derivation of the ‘physical’ shape functions is based on Hencky-Bolle theory of moderately thick plates. The considered finite element was assessed in the past, and the tests showed that the solution convergence was achieved in a wide range of thickness to in-plane dimensions ratios. In this paper a holistic correctness assessment is presented, which covers three criteria: the ellipticity, the consistency and the inf-sup conditions. Fulfilment of these criteria assures the existence of a unique solution, and a stable and optimal convergence to the correct solution. The algorithms of the numerical tests for each test case are presented and the tests are performed for the considered formulation. In result it is concluded that the finite element formulation passes every test and therefore is a good choice for modeling plate structural elements regardless of their thickness.

scholarly journals Inferring Biological Mechanisms by Data-Based Mathematical Modelling: Compartment-Specific Gene Activation during Sporulation in Bacillus subtilis as a Test Case

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Dagmar Iber
Keyword(s):  
Bacillus Subtilis ◽  
Gene Activation ◽  
Experimental Information ◽  
Specific Gene ◽  
Model Parameters ◽  
Test Case ◽  
Detailed Model ◽  
Wide Range ◽  
Technical Advances ◽  
Biological Functionality

Biological functionality arises from the complex interactions of simple components. Emerging behaviour is difficult to recognize with verbal models alone, and mathematical approaches are important. Even few interacting components can give rise to a wide range of different responses, that is, sustained, transient, oscillatory, switch-like responses, depending on the values of the model parameters. A quantitative comparison of model predictions and experiments is therefore important to distinguish between competing hypotheses and to judge whether a certain regulatory behaviour is at all possible and plausible given the observed type and strengths of interactions and the speed of reactions. Here I will review a detailed model for the transcription factor , a regulator of cell differentiation during sporulation in Bacillus subtilis. I will focus in particular on the type of conclusions that can be drawn from detailed, carefully validated models of biological signaling networks. For most systems, such detailed experimental information is currently not available, but accumulating biochemical data through technical advances are likely to enable the detailed modelling of an increasing number of pathways. A major challenge will be the linking of such detailed models and their integration into a multiscale framework to enable their analysis in a larger biological context.

Her2 expression in gastroesophageal cancer (GEC) FFPE tissue using mass spectrometry (MS) and correlation with HER2 gene amplification.

2015 ◽  
Vol 33 (3_suppl) ◽  
pp. 82-82
Author(s):  
Daniel Virgil Thomas Catenacci ◽  
Lei Zhao ◽  
Emma Whitcomb ◽  
Les Henderson ◽  
Emily O'Day ◽  
...  
Keyword(s):  
Cell Lines ◽  
Multiple Linear Regression Model ◽  
Roc Curves ◽  
Therapeutic Benefit ◽  
Molecular Heterogeneity ◽  
Gastroesophageal Cancer ◽  
Her2 Expression ◽  
Her2 Gene ◽  
Robust Model ◽  
Wide Range

82 Background: HER2+ GEC derived benefit from trastuzumab. Her2 IHC is semi-quantitative, subjective, and sensitive to antigen instability; HER2 FISH is laborious, expensive, and subjective. False positivity/negativity have been described. Also, these are low throughput assays; there is known molecular heterogeneity, with several putative biomarkers, and only scarce tissue to assess for each. We sought to evaluate the association of Her2 MS expression with HER2 FISH, along with other markers within the ‘GEC-plex’. Methods: We utilized a previously described unique Her2 peptide and quantification method (Hembrough et al J Clin Oncol 32,2014(suppl 3;abstr17)). The assay was run on 27 cell lines, in parallel with HER2:CEP17 FISH. Her2 expression thresholds were established for HER2 amplification using ROC curves. We adjusted for Her3, Egfr, and Met MS expression levels and sample HER2:CEP17 ratio heterogeneity in a multiple linear regression model. The model/cut-offs were then validated prospectively on GEC tissues (n=142). Results: Her2 MS on cell lines revealed concordance with FISH (HER2:CEP17) ratio (R2=0.75), which improved by adjusting for Her3 MS, Egfr MS, Met MS and HER2:CEP17 heterogeneity (R2>0.98), with significant interactions. IHC correlation with HER2:CEP17 ratio was poor (R2=0.12). A wide range of expression was noted within IHC3+ patients (<150-24671amol/ug). Her2 MS expression (>150 amol/ug) was seen in 72.9% (102/142) of tissues (range <150-24671amol/ug); 9.9% (14/142) had Her2 > 750 amol/ug - all were HER2 FISH amplified. 6/142 (4%) cases <500 amol/ug were clinically ‘HER2amplified’. IHC/FISH results for cases with 550-750 amol/ug demonstrated an ‘equivocal’ zone, not unlike ‘IHC 2+’, but less frequent (8/142, 5.6% vs 46/142 32.4%). Conclusions: The MS HER2 assay can be multiplexed with other GEC biomarkers. A robust model was developed that showed strong correlation of Her2 MS with HER2:CEP17 ratio, particularly when adjusting for covariates Egfr MS, Met MS, Her3 MS, and HER2 FISH heterogeneity. Future analysis will assess the established model as a tool for better prediction of therapeutic benefit from anti-Her2 therapy compared to current methods.

scholarly journals Immunochemical Properties of the Staphylococcal Poly-N-Acetylglucosamine Surface Polysaccharide

2002 ◽  
Vol 70 (8) ◽  
pp. 4433-4440 ◽  
Author(s):  
Tomás Maira-Litrán ◽  
Andrea Kropec ◽  
C. Abeygunawardana ◽  
Joseph Joyce ◽  
George Mark ◽  
...  
Keyword(s):  
Molecular Mass ◽  
Staphylococcus Epidermidis ◽  
Chemical Structure ◽  
Capsular Polysaccharide ◽  
Analytical Techniques ◽  
Molecular Size ◽  
Wide Range ◽  
Molecular Masses ◽  
Surface Polysaccharide ◽  
Average Molecular Masses

ABSTRACT Staphylococcus aureus and Staphylococcus epidermidis often elaborate adherent biofilms, which contain the capsular polysaccharide-adhesin (PS/A) that mediates the initial cell adherence to biomaterials. Biofilm cells produce another antigen, termed polysaccharide intercellular adhesin (PIA), which is composed of a ∼28 kDa soluble linear β(1-6)-linked N-acetylglucosamine. We developed a new method to purify PS/A from S. aureus MN8m, a strain hyperproducing PS/A. Using multiple analytical techniques, we determined that the chemical structure of PS/A is also β(1-6)-N-acetylglucosamine (PNAG). We were unable to find N-succinylglucosamine residues in any of our preparations in contrast to previously reported findings (D. McKenney, K. Pouliot, Y. Wang, V. Murthy, M. Ulrich, G. Doring, J. C. Lee, D. A Goldmann, and G. B. Pier, Science 284:1523-1527, 1999). PNAG was produced with a wide range of molecular masses that could be divided into three major fractions with average molecular masses of 460 kDa (PNAG-I), 100 kDa (PNAG-II), and 21 kDa (PNAG-III). The purified antigens were not soluble at neutral pH unless first dissolved in 5 M HCl and then neutralized with 5 M NaOH. PNAG-I was very immunogenic in rabbits, but the responses of individual animals were variable. Immunization of mice with various doses (100, 50, or 10 μg) of PNAG-I, -II, and -III demonstrated that only PNAG-I was able to elicit an immunoglobulin G (IgG) immune response with the highest titers obtained with 100-μg dose. When we purified a small fraction of PNAG with a molecular mass of ∼780 kDa (PNAG-780) from PNAG-I, significantly higher IgG titers than those in mice immunized with the same doses of PNAG-I were obtained, suggesting the importance of the molecular mass of PNAG in the antibody response. These results further clarify the chemical structure of PS/A and help to differentiate it from PIA on the basis of immunogenicity, molecular size, and solubility.

NOx Emissions of a Premixed Partially Vaporized Kerosene Spray Flame

2006 ◽  
Author(s):  
Stefan Baessler ◽  
Klaus G. Mo¨sl ◽  
Thomas Sattelmayer
Keyword(s):  
Equivalence Ratio ◽  
Glass Tube ◽  
Gas Analysis ◽  
Test Case ◽  
Nox Emissions ◽  
Air Temperatures ◽  
Spray Flames ◽  
Wide Range ◽  
Phase Doppler Anemometer ◽  
Analysis System

An important question for future aero-engine combustors is how partial vaporization influences the NOx emissions of spray flames. In order to address this question an experimental study of the combustion of partially vaporized kerosene/air mixtures was conducted, which assesses the influence of the degree of fuel vaporization on the NOx emissions in a wide range of equivalence ratios covering the entire lean burning regime. The tests were performed at atmospheric pressure, inlet air temperatures of 313 to 376K, a reference mean air velocity of 1.35m/s, and equivalence ratios of 0.6, 0.7 and 0.9 using Jet A1 fuel. An ultrasonic atomizer was used to generate a fuel spray with a Sauter Mean Diameter of approximately 50μm. The spray and the heated air were mixed in a glass tube of 71mm diameter and a variable length of 0.5 to 1m. The temperature of the mixing air and the length of the preheater tube were used for the control of the degree of vaporization. Downstream of the vaporizing section, the mixture was ignited and the flame was stabilized with a hot wire ring that is electrically heated. For local exhaust measurements a temperature controlled suction probe in combination with a conventional gas analysis system were used. The vaporized ratio of the injected fuel was determined by a Phase Doppler Anemometer (PDA). In order to optimize the accuracy of these measurements, extensive validation tests with a patternator method were performed and a calibration curve was derived. The data collected in this study illustrates the effect of the vaporization rate Ψ upstream of the flame front on the NOx emissions, which changes with varying equivalence ratio and degree of vaporization. In the test case with low pre-vaporization, the equivalence ratio only has a minor influence on the NOx emissions. Experiments made with air preheat and higher degrees of vaporization show two effects: With increasing preheat air temperature, NOx emissions increase due to higher effective flame temperatures. However, with an increasing degree of vaporization, emissions become lower due to the dropping number and size of burning droplets, which act as hot spots. A correction for the effect of the preheat temperature was developed. It reveals the effect of the degree of pre-vaporization and shows that the NOx emissions are almost independent of Ψ for near-stoichiometric operation. At overall lean conditions the NOx emissions drop nonlinearly with Ψ. This leads to the conclusion that a high degree of vaporization is required in order to achieve substantial NOx abatement.

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