scholarly journals Tissue-Engineered Vascular Graft of Small Diameter Based on Electrospun Polylactide Microfibers

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
P. V. Popryadukhin ◽  
G. I. Popov ◽  
G. Yu. Yukina ◽  
I. P. Dobrovolskaya ◽  
E. M. Ivan’kova ◽  
...  
Keyword(s):  
Vascular Grafts ◽  
Small Diameter ◽  
Degree Of Crystallinity ◽  
Scanning Electron Microscopy Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthetic Fibers ◽  
Deformation Stability ◽  
Strength And Deformation ◽  
Microscopy Data

Tubular vascular grafts 1.1 mm in diameter based on poly(L-lactide) microfibers were obtained by electrospinning. X-ray diffraction and scanning electron microscopy data demonstrated that the samples treated atT=70°C for 1 h in the fixed state on a cylindrical mandrel possessed dense fibrous structure; their degree of crystallinity was approximately 44%. Strength and deformation stability of these samples were higher than those of the native blood vessels; thus, it was possible to use them in tissue engineering as bioresorbable vascular grafts. The experiments on including implantation into rat abdominal aorta demonstrated that the obtained vascular grafts did not cause pathological reactions in the rats; in four weeks, inner side of the grafts became completely covered with endothelial cells, and fibroblasts grew throughout the wall. After exposure for 12 weeks, resorption of PLLA fibers started, and this process was completed in 64 weeks. Resorbed synthetic fibers were replaced by collagen and fibroblasts. At that time, the blood vessel was formed; its neointima and neoadventitia were close to those of the native vessel in structure and composition.

Determination of Thickness of Multiple Layer Thin Films by X-ray Diffraction Technique

1995 ◽  
Vol 39 ◽  
pp. 637-643
Author(s):  
J. Chaudhuri ◽  
F. Hashmi
Keyword(s):  
Thin Films ◽  
Diffraction Theory ◽  
Scanning Electron Microscopy Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Multiple Layer ◽  
Crystal Model ◽  
Microscopy Data ◽  
Secondary Extinction

In this study, the equations based on x-ray diffraction theory were developed to determine the thickness of multiple layer thin films. The kinematical expression of the integrated reflected intensity from the substrate and films was corrected for the primary and secondary extinction effects assuming a mosaic crystal model. As an example of the application of the method, thicknesses of a double heterostructure system, namely AlAs/AIGaAs/GaAs, were determined. Good agreement was obtained between the results from the x-ray measurement and scanning electron microscopy data demonstrating high precision of this technique.

Zirconolite-Rich Ceramics for Actinide Wastes

1994 ◽  
Vol 353 ◽  
Author(s):  
Eric R Vance ◽  
B. D. Begg ◽  
R. A. Day ◽  
C. J. Ball
Keyword(s):  
Rare Earths ◽  
Solid Solubility ◽  
Scanning Electron Microscopy Data ◽  
X Ray Diffraction ◽  
Absorption Data ◽  
X Ray ◽  
Electron Microscopy Data ◽  
Trivalent Actinides ◽  
Microscopy Data ◽  
X Ray Absorption

AbstractNew X-ray diffraction and scanning electron microscopy data are given for the incorporation of Np and Pu in zirconolite, at levels of tens of percent. The actinide valences and the cations they replace are deduced from the microanalysis of the zirconolite compositions, and X-ray absorption data are used to obtain more direct information on the valences of Ce and Nd, which are used as simulants of Pu and trivalent actinides respectively. Trivalent rare earths and actinides have extensive solid solubility in zirconolite, mainly but not exclusively in the Ca site. Tetravalent rare earths and actinides have considerable solid solubility in the Zr site of zirconolite, and some solubility in the Ca site, but the strong tendency of zirconolite with ions substituted in the Zr site to undergo phase separation complicates structural interpretation. In zirconolite-rich Synroc-type ceramics designed to immobilise waste actinides, the target actinide waste loading has been set at 20 wt% and early leach results indicate the durability is at least as good as that of Synroc-C.

Synthesis of YBa2Cu3O7−x by chemical precursors

1991 ◽  
Vol 6 (1) ◽  
pp. 11-17 ◽  
Author(s):  
D. E. Peterson ◽  
K. A. Kubat-Martin ◽  
T. G. George ◽  
T. G. Zocco ◽  
J. D. Thompson
Keyword(s):  
Single Phase ◽  
High Temperature Superconductor ◽  
Superconducting Phase ◽  
Synthesis Methods ◽  
Scanning Electron Microscopy Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Microscopy Data ◽  
Microscopy Data ◽  
Synthesis Approach

An alternative synthetic route for obtaining bulk forms of the high temperature superconductor YBa2Cu3O7−x has been investigated. The approach is based on first preparing the phases Y2Cu2O5 and BaCuO2, followed by a single sintering of an appropriate mixture of these intermediate compounds to produce the superconducting phase. The resulting materials are largely single-phase as shown by x-ray diffraction, and have densities as high as 86% of the theoretical value, and superconducting onset temperatures of 93 K with magnetic shielding factors ranging from 0.85 to 1.02 (±0.05). Metallography and scanning electron microscopy data were also obtained on the best (high Tc, high shielding factors) of the samples. This synthesis approach is believed to be simpler, more reproducible, and has the potential of producing better materials than previously used bulk synthesis methods.

Effect of the Pulse Laser Radiation on the Stabilization of the ZrO2 and HFO2 High-Temperature Phases

2015 ◽  
Vol 245 ◽  
pp. 200-203 ◽  
Author(s):  
Maxim Alexandrovich Pugachevskii ◽  
Viktor Igorevich Panfilov
Keyword(s):  
High Temperature ◽  
Transmission Electron Microscopy Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Good Thermal Stability ◽  
Quantitative Content ◽  
Electron Microscopy Data ◽  
Cubic Phases ◽  
Transmission Electron ◽  
Microscopy Data

The conditions of formation of the ZrO2 and HfO2 high-temperature (tetragonal and cubic) phases in the ablated nanoparticles were investigated. X-ray diffraction and transmission electron microscopy data demonstrate that laser intensities above 109 W/m2 ensure the formation of the ZrO2 high-temperature phases, while intensities above 5·109 W/m2 do the formation of the HfO2 high-temperature phases. Quantitative content of the high-temperature phases in layers of the ablated nanoparticles increases with raising the intensity. The obtained nanoparticles exhibit good thermal stability.

scholarly journals Effect of indium content on X- ray diffraction and optical constants of InxSe1-x thin films

2019 ◽  
Vol 14 (29) ◽  
pp. 55-72
Author(s):  
Bushra A. Hasan
Keyword(s):  
Thin Films ◽  
Optical Constants ◽  
Indium Content ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Dispersion Energy ◽  
X Ray ◽  
Evaporation Technique ◽  
High Indium Content ◽  
Diffraction Patterns

Alloys of InxSe1-x were prepared by quenching technique withdifferent In content (x=10, 20, 30, and 40). Thin films of these alloyswere prepared using thermal evaporation technique under vacuum of10-5 mbar on glass, at room temperature R.T with differentthicknesses (t=300, 500 and 700 nm). The X–ray diffractionmeasurement for bulk InxSe1-x showed that all alloys havepolycrystalline structures and the peaks for x=10 identical with Se,while for x=20, 30 and 40 were identical with the Se and InSestandard peaks. The diffraction patterns of InxSe1-x thin film showthat with low In content (x=10, and 20) samples have semicrystalline structure, The increase of indium content to x=30decreases degree of crystallinity and further increase of indiumcontent to x=40 leads to convert structure to amorphous. Increase ofthickness from 300 to 700nm increases degree of crystallinity for allindium content. Transmittance measurements were used to calculaterefractive index n and the extinction coefficient k using Swanepole’smethod. The optical constants such as refractive index (n), extinctioncoefficient (k) and dielectric constant (εr, εi) increases for low indiumcontent samples and decreases for high indium content samples,while increase of thickness increases optical constants for all xvalues. The oscillator energy E0, dispersion energy Ed, and otherparameters have been determined by Wemple - DiDomenico singleoscillator approach.

New observations on the small-angle x-ray diffraction of synthetic fibers

1950 ◽  
Vol 5 (6) ◽  
pp. 737-738 ◽  
Author(s):  
L. M. Arnett ◽  
E. P. H. Meibohm ◽  
A. F. Smith
Keyword(s):  
Small Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthetic Fibers

Preparation of nanocellulose by hydrolysis with ionic liquids and two-step hydrolysis with ionic liquids and enzymes

2021 ◽  
Vol 116 ◽  
pp. 5-14
Author(s):  
Marta Babicka ◽  
Magdalena Woźniak ◽  
Kinga Szentner ◽  
Sławomir Borysiak ◽  
Krzysztof Dwiecki ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Degree Of Crystallinity ◽  
Cellulolytic Enzyme ◽  
X Ray Diffraction ◽  
Production Methods ◽  
Step Process ◽  
X Ray ◽  
One Step ◽  
Xrd Patterns ◽  
The One

The aim of this study was to compare parameters of nanocellulose obtained by two different procedures: hydrolysis with ionic liquids (1-allyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium acetate) and hydrolysis with ionic liquids in combination with hydrolysis using a cellulolytic enzyme from Trichoderma reesei. Avicel cellulose was treated with two ionic liquids: 1-allyl-3-methylimidazolium chloride (AmimCl) and 1-ethyl 3-methylimidazolium acetate (EmimOAc). In the two-step hydrolysis cellulose after treatment with ionic liquids was additionally hydrolyzed with a solution of enzymes. In order to characterize the obtained material, the following analyses were used: infrared spectroscopy, X-ray diffraction and dynamic light scattering. The results indicated that cellulose obtained by two-step nanocellulose production methods (first hydrolysis with ionic liquids and then with enzymes) showed similar parameters (particle size, XRD patterns and degree of crystallinity) as the material after the one-step process, i.e. hydrolysis with ionic liquids.

Fibrous Minerals and Synthetic Fibers

1989 ◽  
Author(s):  
H. Catherine W. Skinner ◽  
Malcolm Ross ◽  
Clifford Frondel
Keyword(s):  
Crystal Structure ◽  
Chemical Composition ◽  
Chemical Properties ◽  
Type Specimen ◽  
Mineral Species ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthetic Fibers ◽  
Fibrous Minerals ◽  
The Common

A mineral is a naturally occurring, crystalline inorganic compound with a specific chemical composition and crystal structure. Minerals are commonly named to honor a person, to indicate the geographic area where the mineral was discovered, or to highlight some distinctive chemical, crystallographic, or physical characteristic of the substance. Each mineral sample has some obvious properties: color, shape, texture, and perhaps odor or taste. However, to determine the precise composition and crystal structure necessary to accurately identify the species, one or several of the following techniques must be employed: optical, x-ray diffraction, transmission electron microscopy and diffraction, and chemical and spectral analyses. The long history of bestowing names on minerals has provided some confusing legacies. Many mineral names end with the suffix “ite,” although not most of the common species; no standard naming practice has ever been adopted. Occasionally different names have been applied to samples of the same mineral that differ only in color or shape, but are identical to each other in chemical composition and crystal structure. These names, usually of the common rock-forming minerals, are often encountered and are therefore accepted as synonyms or as varieties of bona fide mineral species. The Fibrous Minerals list (Appendix 1) includes synonyms. A formal description of a mineral presents all the physical and chemical properties of the species. In particular, distinctive attributes that might facilitate identification are noted, and usually a chemical analysis of the first or “type” specimen on which the name was originally bestowed is included. As an example, the complete description of the mineral brucite (Mg(OH)2), as it appears in Dana’s System of Mineralogy, is presented as Appendix 3. Note the complexity of this chemically simple species and the range of information available. In the section on Habit (meaning shape or morphology) both acicular and fibrous forms are noted. The fibrous variety, which has the same composition as brucite, is commonly encountered (see Fig. 1.1D) and is known by a separate name, “nemalite.” Tables to assist in the systematic determination of a mineral species are usually based on quantitative measurements of optical properties (using either transmitted or reflected light, as appropriate) or on x-ray diffraction data.

scholarly journals Characterization of Serpentines from Different Regions by Transmission Electron Microscopy, X-ray Diffraction, BET Specific Surface Area and Vibrational and Electronic Spectroscopy

Fibers ◽  
2019 ◽  
Vol 7 (5) ◽  
pp. 47 ◽  
Author(s):  
Miguel A. Rivero Crespo ◽  
Dolores Pereira Gómez ◽  
María V. Villa García ◽  
José M. Gallardo Amores ◽  
Vicente Sánchez Escribano
Keyword(s):  
Electron Microscopy ◽  
Relative Intensity ◽  
Electronic Spectroscopy ◽  
Visible Region ◽  
Band Gap Energy ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Oh Groups ◽  
X Ray ◽  
Xrd Patterns

Serpentinite powdered samples from four different regions were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), SBET and porosity measurements, UV-Vis and Infrared Spectroscopy of the skeletal region and surface OH groups. SEM micrographs of the samples showed a prismatic morphology when the lizardite was the predominant phase, while if antigorite phase prevailed, the particles had a globular morphology. The few fibrous-shaped particles, only observed by SEM and weakly detected by XRD on MO-9C and MO13 samples, were characteristic of the chrysotile phase. All diffraction XRD patterns showed characteristic peaks of antigorite and lizardite serpentine phases, with crystallite sizes in the range 310–250 Å and with different degrees and types of carbonation processes, one derived from the transformation of the serpentine, generating dolomite, and another by direct precipitation of calcite. The SBET reached values between 38–24 m2∙g−1 for the samples less crystalline, in agreement with the XRD patterns, while those with a higher degree of crystallinity gave values close to 8–9 m2∙g−1. In the UV region all electronic spectra were dominated by the absorption edge due to O2− → Si4+ charge transfer transition, with Si4+ in tetrahedral coordination, corresponding to a band gap energy of ca 4.7 eV. In the visible region, 800–350 nm, the spectra of all samples, except Donai, presented at least two weak and broad absorptions centred in the range 650–800 and 550–360 nm, associated with the presence of Fe3+ ions from the oxidation of structural Fe2+ ions in the serpentinites ((MgxFe2+1−x)3Si2O5(OH)4). The relative intensity of the IR bands corresponding to the stretching modes of the OH’s groups indicated the prevalence of one of the two phases, antigorite or lizardite, in the serpentinites. We proposed that the different relative intensity of these bands could be considered as diagnostic to differentiate the predominance of these phases in serpentinites.

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