scholarly journals PET Fibers Modified with Cloisite Nanoclay

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 774 ◽  
Author(s):  
Janusz Fabia ◽  
Andrzej Gawłowski ◽  
Monika Rom ◽  
Czesław Ślusarczyk ◽  
Anna Brzozowska-Stanuch ◽  
...  
Keyword(s):  
Thermogravimetric Analysis ◽  
Flame Retardant ◽  
Evolved Gas Analysis ◽  
Structural Parameters ◽  
Spectrometric Method ◽  
Limiting Oxygen Index ◽  
X Ray ◽  
X Ray Scattering ◽  
Pet Fibers ◽  
Ray Scattering

The alternative method of reducing the flammability of polyethylene terephthalate (PET) fibers, analogous to dyeing of PET fibers with dispersed dyes in a high-temperature bath, was proposed. A commercial organophilic montmorillonite Cloisite®15A (C15A) was applied as a flame retardant. The aim of the presented work was to evaluate the effectiveness of the introduced modifier and the improvement of the flame-retardant properties of PET fibers by limiting oxygen index (LOI) and thermogravimetric analysis (TGA) measurements. Evolved gas analysis (EGA) by spectrometric method (FTIR) during coupled thermogravimetric analysis (TGA) was applied in order to confirm no increase in the toxicity of volatile degradation products released from burning modified fibers. The nanocomposite nature of modified fibers was confirmed based on the structural parameters of the fibers determined using wide-angle X-ray scattering (WAXS) and small angle X-ray scattering (SAXS) X-ray diffraction methods.

Small angle X-ray scattering study of porosity variation in a styrene-divinylbenzene copolymer

1981 ◽  
Vol 46 (7) ◽  
pp. 1675-1681 ◽  
Author(s):  
Josef Baldrian ◽  
Božena N. Kolarz ◽  
Henrik Galina
Keyword(s):  
Small Angle ◽  
Structural Parameters ◽  
Two Phase ◽  
X Ray ◽  
Porosity Variation ◽  
Swelling Agent ◽  
X Ray Scattering ◽  
Styrene Divinylbenzene ◽  
Ray Scattering

Porosity variations induced by swelling agent exchange were studied in a styrene-divinylbenzene copolymer. Standard methods were used in the characterization of copolymer porosity in the dry state and the results were compared with related structural parameters derived from small angle X-ray scattering (SAXS) measurements as developed for the characterization of two-phase systems. The SAXS method was also used for porosity determination in swollen samples. The differences in the porosity of dry samples were found to be an effect of the drying process, while in the swollen state the sample swells and deswells isotropically.

scholarly journals Determination of nanostructure of liposomes containing two model drugs by X-ray scattering from a synchrotron source

2013 ◽  
Vol 20 (5) ◽  
pp. 721-728 ◽  
Author(s):  
Alexandr Nasedkin ◽  
Jan Davidsson ◽  
Mont Kumpugdee-Vollrath
Keyword(s):  
Experimental Data ◽  
Small Angle ◽  
Structural Parameters ◽  
Water Layer ◽  
Synchrotron Source ◽  
X Ray ◽  
X Ray Scattering ◽  
Extract Information ◽  
Ray Scattering

Small-angle X-ray scattering has been employed to study how the introduction of paracetamol and acetylsalicylic acid into a liposome bilayer system affects the system's nanostructure. An X-ray scattering model, developed for multilamellar liposome systems [Pabstet al.(2000),Phys. Rev. E,62, 4000–4009], has been used to fit the experimental data and to extract information on how structural parameters, such as the number and thickness of the bilayers of the liposomes, thickness of the water layer in between the bilayers, size and volume of the head and tail groups, are affected by the drugs and their concentration. Even though the experimental data reveal a complicated picture of the drug–bilayer interaction, they clearly show a correlation between nanostructure, drug and concentration in some aspects. The localization of the drugs in the bilayers is discussed.

Influence of polychromaticity on particle structure determination in small-angle X-ray scattering

2015 ◽  
Vol 48 (6) ◽  
pp. 1935-1942 ◽  
Author(s):  
Wenjia Wang ◽  
Eleonora V. Shtykova ◽  
Vladimir V. Volkov ◽  
Guangcai Chang ◽  
Lianhui Zhang ◽  
...  
Keyword(s):  
Small Angle ◽  
Structural Parameters ◽  
Shape Reconstruction ◽  
The Body ◽  
Particle Structure ◽  
Saxs Data ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

Pink beams are now widely used for small-angle X-ray scattering (SAXS) data collection owing to their high intensity. However, the wavelength spread of a pink beam is a factor of 100 higher than that of a monochromatic beam, thus causing the experimental data to be smeared. To reveal the influence of polychromaticity on shape reconstruction, four geometric bodies (sphere, cube, helix and long cylinder) were used for SAXS data analysis. The results reveal that the influence of polychromaticity on the process of shape reconstruction is significantly more dependent on the geometry of the body than on its size. Scattering objects with smoothed scattering curves can tolerate a higher wavelength spread than those with tortuous curves. It is further demonstrated that the structural parameters calculated from the smeared data sets have little deviation from the ideal ones, which indicates the possibility of using a light source with a greater wavelength spread than a conventional pink beam for special time-resolved SAXS experiments. Finally, it is concluded that SAXS data collected in pink-beam mode can be used directly for structural calculations and model reconstructions without a desmearing procedure.

X-ray scattering of non-graphitic carbon: an improved method of evaluation

2002 ◽  
Vol 35 (5) ◽  
pp. 624-633 ◽  
Author(s):  
Wilhelm Ruland ◽  
Bernd Smarsly
Keyword(s):  
Profile Analysis ◽  
Structural Parameters ◽  
Wide Angle ◽  
Line Profiles ◽  
Improved Method ◽  
X Ray ◽  
X Ray Scattering ◽  
Fitting Procedures ◽  
Method Of Evaluation ◽  
Ray Scattering

The wide-angle X-ray scattering (WAXS) of non-graphitic carbons shows relatively broad and diffuse interference maxima. In most cases, the corresponding line profiles cannot be separated unambiguously, so that an evaluation using profile analysis is difficult. In these cases, fitting procedures for the total scattering curve are more appropriate. This requires theoretical expressions for all interference maxima with a sufficient number of relevant structural parameters to ensure an acceptable fit. In this paper, such expressions are presented for the (hk) lines (intralayer scattering) and the (00l) lines (interlayer scattering), and the application of these expressions to the evaluation of selected WAXS curves is described. Furthermore, the effects of thermal motion, preferred orientation and Compton scattering are discussed.

scholarly journals Domain Organization in Plant Blue-Light Receptor Phototropin2 of Arabidopsis thaliana Studied by Small-Angle X-ray Scattering

2020 ◽  
Vol 21 (18) ◽  
pp. 6638
Author(s):  
Masayoshi Nakasako ◽  
Mao Oide ◽  
Yuki Takayama ◽  
Tomotaka Oroguchi ◽  
Koji Okajima
Keyword(s):  
Blue Light ◽  
Small Angle ◽  
Structural Changes ◽  
Structural Parameters ◽  
Kinase Domain ◽  
Full Length ◽  
Receptor Protein ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

Phototropin2 (phot2) is a blue-light (BL) receptor protein that regulates the BL-dependent activities of plants for efficient photosynthesis. Phot2 is composed of two light-oxygen-voltage sensing domains (LOV1 and LOV2) to absorb BL, and a kinase domain. Photo-activated LOV domains, especially LOV2, play a major role in photo-dependent increase in the phosphorylation activity of the kinase domain. The atomic details of the overall structure of phot2 and the intramolecular mechanism to convert BL energy to a phosphorylation signal remain unknown. We performed structural studies on the LOV fragments LOV1, LOV2, LOV2-linker, and LOV2-kinase, and full-length phot2, using small-angle X-ray scattering (SAXS). The aim of the study was to understand structural changes under BL irradiation and discuss the molecular mechanism that enhance the phosphorylation activity under BL. SAXS is a suitable technique for visualizing molecular structures of proteins in solution at low resolution and is advantageous for monitoring their structural changes in the presence of external physical and/or chemical stimuli. Structural parameters and molecular models of the recombinant specimens were obtained from SAXS profiles in the dark, under BL irradiation, and after dark reversion. LOV1, LOV2, and LOV2-linker fragments displayed minimal structural changes. However, BL-induced rearrangements of functional domains were noted for LOV2-kinase and full-length phot2. Based on the molecular model together with the absorption measurements and biochemical assays, we discuss the intramolecular interactions and domain motions necessary for BL-enhanced phosphorylation activity of phot2.

X-ray scattering from a thickness-modulated phase of lipid membranes

2019 ◽  
Vol 52 (2) ◽  
pp. 440-444
Author(s):  
S. Madhukar ◽  
V. A. Raghunathan
Keyword(s):  
Lipid Membranes ◽  
Structural Parameters ◽  
Membrane Thickness ◽  
X Ray ◽  
X Ray Scattering ◽  
Least Squares Fit ◽  
Order Of Magnitude ◽  
Modulated Phase ◽  
Analytical Expressions ◽  
Ray Scattering

An electron density model for small-angle X-ray scattering from a novel thickness-modulated phase of lipid membranes is presented, and analytical expressions are derived for the intensities of the diffraction peaks. Structural parameters of the membranes in this phase have been determined from a least-squares fit of the calculated intensities to the observed ones. The amplitude of the thickness modulation is found to be about an order of magnitude smaller than the membrane thickness, which accounts for the very small number and very weak intensities of the peaks arising from these modulations.

scholarly journals Effect of Cholesterol and Ibuprofen on DMPC-β-Aescin Bicelles: A Temperature-Dependent Wide-Angle X-ray Scattering Study

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 401 ◽  
Author(s):  
Ramsia Geisler ◽  
Sylvain Prévost ◽  
Rajeev Dattani ◽  
Thomas Hellweg
Keyword(s):  
Structural Parameters ◽  
Ternary Mixtures ◽  
Horse Chestnut ◽  
Triterpenoid Saponin ◽  
Wide Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Molecular Scale ◽  
The Impact ◽  
Ray Scattering

β -aescin is a versatile biosurfactant extracted from the seeds of the horse chestnut tree Aesculus hippocastanum with anti-cancer potential and is commonly used in the food and pharmaceutical and cosmetic industries. In this article, wide-angle X-ray scattering (WAXS) is used in order to study the modifications of the structural parameters at the molecular scale of lipid bilayers in the form of bicelles composed of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and the triterpenoid saponin β -aescin. In particular, the impact on the cooperative phase transition and the structural parameters of the DMPC bilayers at different compositions and temperatures is of special interest. Moreover, we show how cholesterol and the non-steroidal anti-inflammatory drug (NSAID) ibuprofen modulate the structural parameters of the β -aescin-DMPC assemblies on a molecular scale. Ibuprofen and cholesterol interact with different parts of the bilayer, namely the head-region in the former and the tail-region in the latter case allowing for specific molecular packing and phase formation in the binary and ternary mixtures.

scholarly journals Machine learning deciphers structural features of RNA duplexes measured with solution X-ray scattering

IUCrJ ◽  
2020 ◽  
Vol 7 (5) ◽  
pp. 870-880
Author(s):  
Yen-Lin Chen ◽  
Lois Pollack
Keyword(s):  
Machine Learning ◽  
Structural Information ◽  
Structural Parameters ◽  
Supervised Machine Learning ◽  
Scattering Data ◽  
Length Scales ◽  
X Ray ◽  
X Ray Scattering ◽  
Extreme Gradient Boosting ◽  
Ray Scattering

Macromolecular structures can be determined from solution X-ray scattering. Small-angle X-ray scattering (SAXS) provides global structural information on length scales of 10s to 100s of Ångstroms, and many algorithms are available to convert SAXS data into low-resolution structural envelopes. Extension of measurements to wider scattering angles (WAXS or wide-angle X-ray scattering) can sharpen the resolution to below 10 Å, filling in structural details that can be critical for biological function. These WAXS profiles are especially challenging to interpret because of the significant contribution of solvent in addition to solute on these smaller length scales. Based on training with molecular dynamics generated models, the application of extreme gradient boosting (XGBoost) is discussed, which is a supervised machine learning (ML) approach to interpret features in solution scattering profiles. These ML methods are applied to predict key structural parameters of double-stranded ribonucleic acid (dsRNA) duplexes. Duplex conformations vary with salt and sequence and directly impact the foldability of functional RNA molecules. The strong structural periodicities in these duplexes yield scattering profiles with rich sets of features at intermediate-to-wide scattering angles. In the ML models, these profiles are treated as 1D images or features. These ML models identify specific scattering angles, or regions of scattering angles, which correspond with and successfully predict distinct structural parameters. Thus, this work demonstrates that ML strategies can integrate theoretical molecular models with experimental solution scattering data, providing a new framework for extracting highly relevant structural information from solution experiments on biological macromolecules.

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