Characterization of EM field above a single aperture or air-vents of an enclosure for a variable degree of correlation between stochastic sources inside

2017 ◽  
Author(s):  
Nebojsa Doncov ◽  
Biljana Stosic ◽  
Zoran Stankovic ◽  
Johannes Russer ◽  
Michael Haider ◽  
...  
Keyword(s):  
Variable Degree ◽  
Single Aperture ◽  
Em Field ◽  
Stochastic Sources

scholarly journals Preparation and Characterization of Poly(D,L-Lactide-co-Glycolide) Nanoparticles Containing Ascorbic Acid

2007 ◽  
Vol 2007 ◽  
pp. 1-8 ◽  
Author(s):  
Magdalena M. Stevanovic ◽  
Branka Jordovic ◽  
Dragan P. Uskokovic
Keyword(s):  
Ascorbic Acid ◽  
Morphological Characteristics ◽  
Spherical Shape ◽  
Physical Method ◽  
Controlled Delivery ◽  
Variable Degree ◽  
Acid Copolymer ◽  
Copolymer Poly ◽  
Different Content

This paper is covering new, simplistic method of obtaining the system for controlled delivery of the ascorbic acid. Copolymer poly (D,L-lactide-co-glycolide) (DLPLG) nanoparticles are produced using physical method with solvent/nonsolvent systems where obtained solutions were centrifuged. The encapsulation of the ascorbic acid in the polymer matrix is performed by homogenization of water and organic phases. Particles of the DLPLG with the different content of ascorbic acid have different morphological characteristics, that is, variable degree of uniformity, agglomeration, sizes, and spherical shaping. Mean sizes of nanoparticles, which contain DLPLG/ascorbic acid in the ratio 85/150%, were between 130 to 200 nm depending on which stereological parameters are considered (maximal diameters Dmax, feret X, or feret Y). By introducing up to 15% of ascorbic acid, the spherical shape, size, and uniformity of DLPLG particles are preserved. The samples were characterized by infrared spectroscopy, scanning electron microscopy, stereological analysis, and ultraviolet spectroscopy.

scholarly journals Application of Direct Methods to Inorganic Materials Characterization

2014 ◽  
Vol 70 (a1) ◽  
pp. C29-C29
Author(s):  
Jordi Rius
Keyword(s):  
Fourier Transforms ◽  
Direct Methods ◽  
Inorganic Materials ◽  
Data Sets ◽  
Variable Degree ◽  
Patterson Function ◽  
Small Crystals ◽  
Structure Solution ◽  
Using Data

Although in the last years most attention has been paid to the development of direct methods (DM) in the macromolecular field, DM also play an important role in the characterization of inorganic materials. Very challenging is nowadays the structure solution of increasingly small crystals. Here the difficulty is not associated with the large number of atoms but with experimental limitations which may affect the data accuracy and the completeness of the data sets. It is obvious that DM have to adapt to this emerging scientific need. Particularly interesting has been the evolution of Patterson-function DM to cope with these objectives. The initial formulation based on the explicit use of triple-phase sums was modified to permit the calculation with Fourier transforms thus resulting in the more simple and accurate S-FFT algorithm [1]. Thanks to the resulting increased simplicity, this algorithm could be easily adapted to the treatment of powder diffraction data of complex inorganic materials [2]. The practical application of this algorithm is analyzed by using data of some synthetic and natural materials. Recently, the possibility of collecting good quality 3D intensity data from very small nanovolumes by new sophisticated electron diffraction (ED) techniques has become a reality. However, these data sets are often incomplete and, in addition, the intensities are not completely kinematical. The processing of these data sets represents a new challenge for DM. To this purpose a new (even more simple) Patterson-function DM (called delta-recycling) has been developed and tested on precession ED data from inorganic materials with variable degree of difficulty [3]. Phasing with delta-recycling proves to be highly efficient and from the interpretation of the results important practical conclusions can be drawn.

Seismoelectric Surface-Wave Analysis for Characterization of Formation Properties, using Dispersive Relative Spectral Amplitudes

Geophysics ◽  
2021 ◽  
pp. 1-25
Author(s):  
N. Grobbe ◽  
S. A. L. de Ridder
Keyword(s):  
Surface Wave ◽  
Body Wave ◽  
Electrical Potential ◽  
Relative Strength ◽  
Body Waves ◽  
Fluid Viscosity ◽  
Near Surface ◽  
Em Field ◽  
Seismic Body Waves

We study seismoelectric (SE) surface-wave signals and find that they can be used to infer changes in the SE coupling properties at depth. Seismoelectric surface-wave signals have much higher amplitudes than seismoelectric body-wave signals. We propose to measure both the seismic and the electrical potential or electromagnetic (EM) field along the surface of the Earth. We use Dispersive Relative Spectral Amplitudes (DRSA) that measure the frequency-dependent relative strength of electrical signals versus seismic signals associated with seismoelectric surface-wave signals. We show that the DRSA have sensitivity to contrasts in the electrokinetic coupling coefficient and other relevant petrophysical properties at depth. Our discovery can mitigate the major limitation that plagues body wave-based SE methods: the relative weakness of the converted, EM signals from seismic body waves. We envision applications to characterize subsurface rock, fluid and fluid-flow properties (e.g. porosity, permeability, and dynamic fluid viscosity, salinity) in the near surface, for aquifers, and shallow geothermal reservoirs.

Synthesis, Reactivity and Structural Chemistry of 5,10,15,20-Tetraalkylporphyrins

1999 ◽  
Vol 03 (02) ◽  
pp. 99-116 ◽  
Author(s):  
MATHIAS O. SENGE ◽  
INES BISCHOFF ◽  
NORA Y. NELSON ◽  
KEVIN M. SMITH
Keyword(s):  
Crystal Structure ◽  
Experimental Evidence ◽  
Conformational Flexibility ◽  
Variable Degree ◽  
Free Base ◽  
Absorption Bands ◽  
Tert Butyl ◽  
Full Characterization ◽  
Derivatives Of

The synthesis, reactivity and full characterization of a series of meso-tetraalkyl porphyrins and metalloporphyrins with R ≡ n-butyl (6), 2-methyl-propyl (7), isopropyl (8), l-ethyl-propyl (10) and tert-butyl (11) groups are reported. Derivatives of the last of these show considerably bathochromically shifted absorption bands and the crystal structure of Zn ( II )11(pyr) exhibits a severely ruffled macrocycle conformation. Systematic crystallographic studies of the porphyrins showed that the free base porphyrins with R ≡ n-butyl ( H 26), 2-methyl-propyl ( H 27) and 1-ethyl-propyl ( H 210) are planar. A larger conformational variety was found for the metal complexes. While most Ni ( II ) derivatives and Pd ( II )8 showed a ruffled macrocycle conformation with a degree of ruffling exceeding that of meso-unsubstituted porphyrins, both planar and non-planar forms were found for the related Cu ( II ) derivatives. The Zn ( II ) complexes of porphyrins with isopropyl or 1-ethyl-propyl exhibited conformations with variable degree of distortion. Together with comparative structures from the literature, this study provides experimental evidence that considerable conformational flexibility exists for meso-alkylporphyrins with substituents less bulky than tert-butyl groups.

Characterization of habitable exoplanets with simultaneous coronagraphy and astrometry with a single aperture telescope

2012 ◽  
Author(s):  
Olivier Guyon ◽  
Eduardo Bendek ◽  
S. Mark Ammons ◽  
Michael Shao ◽  
Stuart Shaklan ◽  
...  
Keyword(s):  
Single Aperture

scholarly journals Electromagnetic Characterization of Engineered Materials Using Capacitively Loaded Aperture Sensors

Proceedings ◽  
2019 ◽  
Vol 42 (1) ◽  
pp. 31
Author(s):  
Oleksandr Malyuskin
Keyword(s):  
Coplanar Waveguide ◽  
Field Enhancement ◽  
High Sensitivity ◽  
Dipole Antennas ◽  
Artificial Materials ◽  
Novel Method ◽  
Em Field ◽  
Coaxial Probe ◽  
Very High

A novel method for electromagnetic (EM) characterization of engineered artificial materials such as biomaterials, nanomaterials, and composite materials is proposed and experimentally evaluated in this paper. The method is based on resonance transmission properties of capacitively loaded apertures in conductive screens. The advantage of this new method over the existing techniques (free space, loaded waveguide, microstrip and coplanar waveguide resonators, coaxial probe, etc.) is three-fold: (i) resonance EM field enhancement inside the loaded aperture leads to very high sensitivity and therefore accuracy of EM parameters de-embedding, (ii) only small thin samples of material under test are required (with a sample area substantially smaller than squared wavelength of radiation, ~0.01 λ2), (iii) the method is easily scalable over the frequency and wavelength and based on relatively simple permittivity and permeability de-embedding procedure. The experimental setup in the microwave S-band (2–3 GHz) is based on two dipole antennas, capacitive aperture in the conductive screen, unloaded and loaded with material under test, and vector network analyzer (VNA) for signal generation and data acquisition. Analytical de-embedding procedure is developed and applied to the characterization of carbon nanotube (CNT) material microwave absorption. It is demonstrated that the method offers very high accuracy in material characterization based on minimal material samples.

scholarly journals Green synthesis and characterization of carboxymethyl guar gum: Application in textile printing technology

2020 ◽  
Vol 9 (1) ◽  
pp. 212-218
Author(s):  
Dure Najaf Iqbal ◽  
Arif Nazir ◽  
Munawar Iqbal ◽  
Muhammad Yameen
Keyword(s):  
Guar Gum ◽  
Gelling Agent ◽  
Variable Degree ◽  
Reaction Conditions ◽  
Titration Method ◽  
Printing Technology ◽  
Textile Printing ◽  
Alkaline Conditions ◽  
Fabric Handling

AbstractThis study focusses on the synthesis of carboxymethyl guar gum (CMG) via monochloroacetic acid under alkaline conditions. The reaction conditions were also optimized during the course of experiment. Guar derivative with variable degree of substitution (DS) were prepared and were confirmed by Fourier transform infrared (FTIR) spectroscopy. The DS was determined quantitatively by titration method for each derivative. The synthesized guar gum derivatives, being the natural thickners, have been used in textile printing technology. Substituted guar gum has been proved environmental friendly thickener as compared to synthetic thickeners. Penetration properties, fixation ability, colour fastness, levelness and fabric handling was compared with alginate thickener (commercially available). Guar gum thickeners showed enhanced properties versus alginate thickener and can be used as an alternative to synthetic thickeners in view of its green, non-hazardous and economical derivatives. Guar gum is the outstanding natural thickener, stabilizer, gelling agent and could possibly be used in various industrial units including food, cosmetic, textile, oil fracturing and mining.

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