Physico-chemical properties of gemini micelles studied by X-ray scattering and ESR spectroscopy

2015 ◽  
Vol 472 ◽  
pp. 101-108 ◽  
Author(s):  
S. Falsini ◽  
L. Ciani ◽  
A. Arcangeli ◽  
E. Di Cola ◽  
F. Spinozzi ◽  
...  
Keyword(s):  
Esr Spectroscopy ◽  
Chemical Properties ◽  
X Ray ◽  
X Ray Scattering ◽  
Physico Chemical ◽  
Ray Scattering

X-ray scattering from coals

1954 ◽  
Vol 226 (1165) ◽  
pp. 143-169 ◽  
Keyword(s):  
Structural Model ◽  
Fourier Transforms ◽  
Chemical Properties ◽  
Bedding Plane ◽  
Optical Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Wide Range ◽  
Liquid Type ◽  
Ray Scattering

This paper describes the results of X-ray scattering experiments on a series of vitrain-coals of varying rank. The scattering at high angles is interpreted in terms of condensed aromatic layers; the diameters of the layers are determined and are found to increase with increasing rank; the percentage carbon in the form of layers is also estimated. Fourier transforms calculated for the scattering at lower angles show that the layers occur partly singly, and partly in groups of two, three or more stacked parallel to each other. The degree of local parallel stacking increases with increasing rank. There is a preferred orientation of the layers parallel to the bedding plane, which becomes more marked the higher the rank of the coal. The diffraction peak at ~20 Å, found for coals with 85 to 94% C, is considered to be a consequence of ‘liquid-type’ packing of the most frequently occurring groups containing two to three layers. The diameters of the layers determined from the transforms (~8 Å) are in good agreement with the results of intensity calculations, and the values obtained from the scattering at high angles. The scattering at very small angles is measured with a two-crystal spectrometer for spacings up to ~5000 Å. The scattering is related to porosity; the scattering curves do not support the existence of a close-packed arrangement of ‘micelles’ of fairly constant diameter less than ~5000 Å, but suggest that there are anisotropic cracks and pores of a wide range of sizes, some of which must exceed ~5000 Å. The total scattering indicates the existence of disk cracks preferentially orientated parallel to the bedding plane. In terms of a proposed structural model, coalification is a process of condensation, ordering of the layers, and flattening of the structure. A ‘liquid-type’ structure is formed, which is most perfect at ~89% C and accounts for the minimum of porosity. Anthracitization is probably accompanied by a clustering of the layers, which results in a rapid increase of layer diameter, in irregular packing, and in an increase of porosity. The properties of the proposed structure model of coal are discussed and compared with the known physical and chemical properties of coal, e. g. density, optical data, porosity and mechanical properties, and some of the problems still outstanding are indicated.

scholarly journals FUNCTIONAL MATERIALS FROM PAPER WASTES. II. CELLULOSE HYDROGELS WITH HIGH WATER RETEN-TION CAPACITY OBTAINED FROM SOLUTIONS OF WASTE PAPER IN DMAC/LiCl

2021 ◽  
pp. 83-98
Author(s):  
Aleksandra Mikhaylovna Mikhailidi ◽  
Nina Yefimovna Kotelnikova
Keyword(s):  
Structural Modification ◽  
Chemical Properties ◽  
Functional Materials ◽  
High Water ◽  
Waste Paper ◽  
Crystallographic Structure ◽  
X Ray ◽  
X Ray Scattering ◽  
Physico Chemical ◽  
Freeze Dried

An efficient process for recycling paper and cardboard wastes via dissolution in N,N-dimethylacetamide/lithium chloride (DMAc/LiCl) system and regeneration from solutions to obtain hydrogels has been developed. Pretreatment of waste paper has been carried out by thermal defibrillation of waste paper in water and homogenization to obtain fibre samples. The dissolution of fibre materials has been performed in two ways varying the process temperature and the way the reagents have been introduced. Regeneration from solutions has been carried out by spontaneous gelation without the use of antisolvents, at room temperature and atmospheric pressure. As a result, hydrogels were obtained which differed in color and transparency depending on feedstock. The physico-chemical properties of the hydrogels have been characterized. It has been shown that they were stable in an aqueous medium, capable of retaining a significant amount of water (over 4000 wt.%), and were porous systems which has been confirmed by scanning electron microscopy. According to a wide-angle X-ray scattering, the crystallographic structure of the pristine waste paper samples corresponded to a structural modification of cellulose I. Regenerated samples as freeze-dried hydrogels had the structure of cellulose II. A functional and an elemental composition studied with FTIR spectroscopy and an energy-dispersive X-ray microanalysis characterized these hydrogels as the cellulose samples containing small amount of inorganic impurities. The resulting hydrogels had a system of through pores of different sizes, and this predetermined their use as adsorbents and active matrices.

scholarly journals Microscopy and Spectroscopy Techniques for Characterization of Polymeric Membranes

Membranes ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 33 ◽  
Author(s):  
Yousef Alqaheem ◽  
Abdulaziz A. Alomair
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Chemical Properties ◽  
Data Interpretation ◽  
Physical Structure ◽  
Polymeric Membrane ◽  
X Ray ◽  
Characterization Techniques ◽  
X Ray Scattering ◽  
Ray Scattering

Polymeric membrane is a proven technology for water purification and wastewater treatment. The membrane is also commercialized for gas separation, mainly for carbon dioxide removal and hydrogen recovery. Characterization techniques are excellent tools for exploring the membrane structure and the chemical properties. This information can be then optimized to improve the membrane for better performance. In this paper, characterization techniques for studying the physical structure such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) are discussed. Techniques for investigating the crystal structure such as X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), and wide-angle X-ray scattering (WAXS) are also considered. Other tools for determining the functional groups such Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and nuclear magnetic resonance (NMR) are reviewed. Methods for determining the elemental composition such as energy-dispersion X-ray spectroscopy (EDS), X-ray fluorescent (XRF), and X-ray photoelectron spectroscopy (XPS) are explored. The paper also gives general guidelines for sample preparation and data interpretation for each characterization technique.

Microtubule nucleation sequence studied by time-resolved x-ray scattering and electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 766-767
Author(s):  
Eva-Maria Mandelkow ◽  
Eckhard Mandelkow ◽  
Joan Bordas
Keyword(s):  
Electron Microscopy ◽  
Dynamic Equilibrium ◽  
Time Resolved ◽  
X Ray ◽  
Additional Information ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Microtubule Growth ◽  
Ray Patterns ◽  
Ray Scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

Time-Resolved Cryo-Electron Microscopy of Oscillating Microtubules

1990 ◽  
Vol 48 (1) ◽  
pp. 502-503
Author(s):  
Eva-Maria Mandelkow ◽  
Ron Milligan
Keyword(s):  
Electron Microscopy ◽  
Dynamic Instability ◽  
Entire Solution ◽  
Reaction Scheme ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
A Chain ◽  
Ray Scattering

Microtubules form part of the cytoskeleton of eukaryotic cells. They are hollow libers of about 25 nm diameter made up of 13 protofilaments, each of which consists of a chain of heterodimers of α-and β-tubulin. Microtubules can be assembled in vitro at 37°C in the presence of GTP which is hydrolyzed during the reaction, and they are disassembled at 4°C. In contrast to most other polymers microtubules show the behavior of “dynamic instability”, i.e. they can switch between phases of growth and phases of shrinkage, even at an overall steady state [1]. In certain conditions an entire solution can be synchronized, leading to autonomous oscillations in the degree of assembly which can be observed by X-ray scattering (Fig. 1), light scattering, or electron microscopy [2-5]. In addition such solutions are capable of generating spontaneous spatial patterns [6].In an earlier study we have analyzed the structure of microtubules and their cold-induced disassembly by cryo-EM [7]. One result was that disassembly takes place by loss of protofilament fragments (tubulin oligomers) which fray apart at the microtubule ends. We also looked at microtubule oscillations by time-resolved X-ray scattering and proposed a reaction scheme [4] which involves a cyclic interconversion of tubulin, microtubules, and oligomers (Fig. 2). The present study was undertaken to answer two questions: (a) What is the nature of the oscillations as seen by time-resolved cryo-EM? (b) Do microtubules disassemble by fraying protofilament fragments during oscillations at 37°C?

X-ray scattering by 1D molecular Guinier-Preston zones in ordered smectic phases

1992 ◽  
Vol 2 (6) ◽  
pp. 899-913 ◽  
Author(s):  
Patrick Davidson ◽  
Elisabeth Dubois-Violette ◽  
Anne-Marie Levelut ◽  
Brigitte Pansu
Keyword(s):  
X Ray ◽  
X Ray Scattering ◽  
Smectic Phases ◽  
Ray Scattering

An X-ray Scattering Study of Laterally Modulated Structures: Investigation of Coherence and Resolution Effects with a Grating

1996 ◽  
Vol 6 (8) ◽  
pp. 1085-1094 ◽  
Author(s):  
A. Gibaud ◽  
J. Wang ◽  
M. Tolan ◽  
G. Vignaud ◽  
S. K. Sinha
Keyword(s):  
X Ray ◽  
X Ray Scattering ◽  
Modulated Structures ◽  
Scattering Study ◽  
Ray Scattering

Pixel detectors: New detectors for X-ray scattering

2002 ◽  
Vol 12 (6) ◽  
pp. 385-390 ◽  
Author(s):  
J.-F. Bérar ◽  
L. Blanquart ◽  
N. Boudet ◽  
P. Breugnon ◽  
B. Caillot ◽  
...  
Keyword(s):  
X Ray ◽  
X Ray Scattering ◽  
Pixel Detectors ◽  
Ray Scattering
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