scholarly journals Inverse problem for tripotential measures in the study of buried cavities

1996 ◽  
Vol 39 (1) ◽  
Author(s):  
P. Cosentino ◽  
D. Luzio ◽  
R. Martorana
Keyword(s):  
Apparent Resistivity ◽  
Random Noise ◽  
Source Parameters ◽  
Spherical Shape ◽  
Average Diameter ◽  
Unknown Parameters ◽  
Fundamental Parameters ◽  
Spherical Models ◽  
Source Models ◽  
Biased Estimates

This paper presents a solution to the inverse electrical problem for the interpretation of apparent resistivity anomalies due to empty buried cavities of quasi-spherical shape when tripotential measures are carried out. The anomalies of the apparent resistivities ra,rb andrg,and the composed resistivitiesrmand rt were previously calculated for a sufficient class of spherical models of resistivity anomalies. Then, for the whole class of models, some functionals of spatial distribution of the apparent and composed resistivity were identified and analyzed. They represent the average characteristics of the anomalies and, depending in a simple way on the fundamental parameters of the sources of the anomalies (average diameter and depth), they allow reliable estimates to be determined. Among the studied functionals, those allowing the most stable and less biased estimates of the anomaly source parameters are identified by numerical simulations with random noise perturbed data. Finally the trend of standard deviation and bias of the estimates of the unknown parameters were analyzed by varying the source models and the set of functionals used for the inversion.

scholarly journals Co-doped MnFe2O4 nanoparticles: magnetic anisotropy and interparticle interactions

2019 ◽  
Vol 10 ◽  
pp. 856-865 ◽  
Author(s):  
Bagher Aslibeiki ◽  
Parviz Kameli ◽  
Hadi Salamati ◽  
Giorgio Concas ◽  
Maria Salvador Fernandez ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Structural Changes ◽  
Spherical Shape ◽  
Average Diameter ◽  
Cobalt Doping ◽  
Interparticle Interactions ◽  
Co Doping ◽  
Particle Anisotropy ◽  
Interaction Regime

The effect of cobalt doping on the magnetic properties of Mn1− x Co x Fe2O4 nanoparticles was investigated. All samples consist of ensembles of nanoparticles with a spherical shape and average diameter of about 10 nm, showing small structural changes due to the substitution. Besides having the same morpho-structural properties, the effect of the chemical composition, i.e., the amount of Co doping, produces marked differences on the magnetic properties, especially on the magnetic anisotropy, with evident large changes in the coercive field. Moreover, Co substitution has a profound effect on the interparticle interactions, too. A dipolar-based interaction regime is detected for all samples; in addition, the intensity of the interactions shows a possible relation with the single particle anisotropy. Finally, the sample with the strongest interaction regime shows a superspin glass state confirmed by memory effect dynamics.

scholarly journals Synthesis, structural characterization, cytotoxicity and encapsulation studies of N,Nʹ-(1, 2-dicyano-1,2-vinylene)-bis(4-hydroxysalicylideneaminato) di(p-chlorobenzyl)tin as potential anticancer drug

2019 ◽  
Vol 42 (1) ◽  
pp. 94-101
Author(s):  
Nur Adibah Mohd Amin ◽  
Rusnah Syahila Duali Hussen ◽  
See Mun Lee ◽  
Kae Shin Sim ◽  
Suerialoasan Navanesan
Keyword(s):  
Drug Release ◽  
Cancer Cell ◽  
Cancer Cell Line ◽  
Spherical Shape ◽  
Average Diameter ◽  
Diphenyltetrazolium Bromide ◽  
Ft Ir ◽  
Phosphate Buffered Saline ◽  
Mcf 7

Abstract Two new diorganotin(IV) complexes with the general formula (RC7H6)2Sn(L) (where RC7H6 = p-ClBn, C1; and p-FBn, C2) were prepared based on the reaction of 2,3-bis(4-hydroxysalicylidene-amino)-maleic nitrile (L) with substituted dibenzyltin(IV) dichloride. The structures were confirmed by elemental analysis, Fourier transform infrared (FT-IR), proton and carbon nuclear magnetic resonance (1H and 13C NMR). They were tested against several cancer cell lines by using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. C1, which was most effective against MCF-7 breast cancer cell line, was further investigated in formulation and encapsulation studies, including drug encapsulation efficiency, particle size, morphology and in vitro drug release. An encapsulation of about 90% was achieved with particles of 128 nm average diameter. Field emission scanning electron microscopy (FESEM) confirmed a spherical shape for the encapsulated C1. The cumulative drug release over a period of 60 days in phosphate buffered saline (PBS) at pH 7.4 was 75%. Based on these results, the formulated drug has the potential of a slow release drug for cancer chemotherapy.

scholarly journals A Study On Dispersion Stability Of Nickel Nanoparticles Synthesized By Wire Explosion In Liquid Media

2015 ◽  
Vol 60 (2) ◽  
pp. 1379-1382 ◽  
Author(s):  
C.K. Kim ◽  
G.-J. Lee ◽  
M.K. Lee ◽  
C.K. Rhee
Keyword(s):  
Nickel Nanoparticles ◽  
Spherical Shape ◽  
Physical Method ◽  
Average Diameter ◽  
Dispersion Stability ◽  
Wire Explosion ◽  
Transmission Electron ◽  
One Step ◽  
Polymer Surfactant ◽  
Microscopy Images

Abstract In this study, nickel nanoparticles were synthesized in ethanol using portable pulsed wire evaporation, which is a one-step physical method. From transmission electron microscopy images, it was found that the Ni nanoparticles exhibited a spherical shape with an average diameter of 7.3 nm. To prevent aggregation of the nickel nanoparticles, a polymer surfactant was added into the ethanol before the synthesis of nickel nanoparticles, and adsorbed on the freshly synthesized nickel nanoparticles during the wire explosion. The dispersion stability of the prepared nickel nanofluids was investigated by zeta-potential analyzer and Turbiscan optical analyzer. As a result, the optimum concentration of polymer surfactant to be added was suggested for the maximized dispersion stability of the nickel nanofluids.

scholarly journals Antimicrobial Potential of Silver Nanoparticles Synthesized Using Medicinal Herb Coptidis rhizome

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2268 ◽  
Author(s):  
Garima Sharma ◽  
Ju-Suk Nam ◽  
Ashish Sharma ◽  
Sang-Soo Lee
Keyword(s):  
Silver Nanoparticles ◽  
Aqueous Extract ◽  
Inductively Coupled Plasma ◽  
Antimicrobial Property ◽  
Spherical Shape ◽  
Silver Ions ◽  
Average Diameter ◽  
Xrd Analysis ◽  
Visible Absorption ◽  
Biosynthesized Agnps

Coptidis rhizome contains several alkaloids that are bioactive agents of therapeutic value. We propose an eco-friendly method to synthesize biocompatible silver nanoparticles (AgNPs) using the aqueous extract of Coptidis rhizome. Silver ions were reduced to AgNPs using the aqueous extract of Coptidis rhizome, indicating that Coptidis rhizome can be used for the biosynthesis of AgNPs. The time and the concentration required for conversion of silver ions into AgNPs was optimized using UV-absorbance spectroscopy and inductively coupled plasma spectroscopy (ICP). Biosynthesized AgNPs showed a distinct UV-Visible absorption peak at 420 nm. ICP analysis showed that the time required for the completion of biosynthesis was around 20 min. Microscopic images showed that nanoparticles synthesized were of spherical shape and the average diameter of biosynthesized AgNPs was less than 30 nm. XRD analysis also confirmed the size of AgNps and revealed their crystalline nature. The interaction of AgNPs with phytochemicals present in Coptidis rhizome extract was observed in FTIR analysis. The antimicrobial property of AgNPs was evaluated using turbidity measurements. Coptidis rhizome-mediated biosynthesized AgNPs showed significant anti-bacterial activities against Escherichia coli and Staphylococcus aureus that are commonly involved in various types of infections, indicating their potential as an effective anti-bacterial agent.

scholarly journals Three-dimensional interpretation of magnetic and gravity anomalies using the finite-difference similarity transform

Geophysics ◽  
2010 ◽  
Vol 75 (4) ◽  
pp. L79-L90 ◽  
Author(s):  
Daniela Gerovska ◽  
Marcos J. Araúzo-Bravo ◽  
Kathryn Whaler ◽  
Petar Stavrev ◽  
Alan Reid
Keyword(s):  
Finite Difference ◽  
Random Noise ◽  
Source Parameters ◽  
Magnetization Vector ◽  
Real Data ◽  
Index Formula ◽  
Magnetic Data ◽  
Horizontal Position ◽  
Structural Index ◽  
Similarity Transform

We present an automatic procedure for interpretation of magnetic or gravity gridded anomalies based on the finite-difference similarity transform (FDST). It is called MaGSoundFDST (magnetic and gravity sounding based on the finite-difference similarity transform) and uses a “focusing” principle in contrast to deriving multiple clusters of many solutions as in the widely used Euler deconvolution method. The source parameters are characterized by isolated solutions, and the interpreter obtains parallel images showing the horizontal position, depth, and structural index [Formula: see text] value. The underlying principle is that the FDST of a potential field anomaly becomes zero or linear at all observation points when the central point of similarity (CPS) of the transform coincides with a source field’s singular point and a correct [Formula: see text] value is used. The procedure involves calculating a 3D function that evaluates the linearity of the FDST for a series of [Formula: see text] values, using a moving window and sounding the subsurface along a verticalline under each window center. We then combine the 3D results for different [Formula: see text] values into a single map whose minima determine the horizontal position of the sources. The [Formula: see text] value and the CPS depth associated with each minimum determine the [Formula: see text] value and depth of the corresponding source. Only one estimate characterizes a simple source, which is a major advantage over other window-based procedures. MaGSoundFDST uses only the measured anomalous field and its upward continuation, thus avoiding the direct use of field derivatives. It is independent of the magnetization-vector direction in the magnetic data case. The procedure accounts for a linear background of local gravity or magnetic anomalies and has been applied effectively to several cases of synthetic and real data. MaGSoundFDST shares common features with the magnetic and gravity sounding based on the differential similarity transform (MaGSoundDST) but is more stable in estimating depth and structural index in the presence of random noise.

Inversion of borehole normal resistivity logs

Geophysics ◽  
1984 ◽  
Vol 49 (9) ◽  
pp. 1541-1548 ◽  
Author(s):  
Fang‐Wei Yang ◽  
Stanley H. Ward
Keyword(s):  
Theoretical Model ◽  
Ridge Regression ◽  
Arbitrary Number ◽  
Inverse Method ◽  
Apparent Resistivity ◽  
Random Noise ◽  
High Resistivity ◽  
Number Of Layers ◽  
Boundary Position ◽  
Resistivity Logs

This paper reports on an investigation of the inversion of borehole normal resistivity data via ridge regression. Interpretation is afforded of individual thin beds and of complicated layered structures. A theoretical solution is given for a layered model containing an arbitrary number of layers in the forward problem. Two forward model results for resistive and conductive thin beds indicate that for high‐resistivity contrasts, the departure between true and apparent resistivity may be more important than the effects caused by the variations in borehole diameter and mud resistivity. Four normal resistivity logs were chosen to test the inversion scheme. Two of the logs were theoretical logs with and without random noise added, and the remaining two were field examples. Theoretical model results and field examples indicate that the inverse method can be used to obtain the resistivity for each layer when the boundary position is known, but it also can be used to obtain the thickness and resistivity for each layer simultaneously.

Fabrication and Electrical Characterization of Metal-Silicide Nanocrystals for Nano Floating Gate Nonvolatile Memory

2009 ◽  
Vol 1160 ◽  
Author(s):  
Seung Jong Han ◽  
Ki Bong Seo ◽  
Dong Uk Lee ◽  
Eun Kyu Kim ◽  
Se-Mam Oh ◽  
...  
Keyword(s):  
Nonvolatile Memory ◽  
Electrical Characterization ◽  
Spherical Shape ◽  
Average Diameter ◽  
Floating Gate ◽  
Flat Band ◽  
Hysteresis Curve ◽  
Flat Band Voltage ◽  
Transmission Electron ◽  
Floating Gate Memory

AbstractWe have fabricated the nano-floating gate memory with the TiSi2 and WSi2 nanocrystals embedded in the dielectrics. The TiSi2 and WSi2 nanocrystals were created by using sputtering and rapidly thermal annealing system, and then their morphologies were investigated by transmission electron microscopy. These nanocrystals have a spherical shape with an average diameter of 2-5 nm. The electrical properties of the nano-floating gate memory with TiSi2 and WSi2 nanocrystals were characterized by capacitance-voltage (C-V) hysteresis curve, memory speed and retention. The flat-band voltage shifts of the TiSi2 and WSi2 nanocrystals capacitors obtained appeared up to 4.23 V and 4.37 V, respectively. Their flat-band voltage shifts were maintained up to 1.6 V and 1 V after 1 hr.

scholarly journals Photoregulation of Gold Nanoparticles Stabilized in a Diacetylenic Nanocapsule

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Saowalak Somjid ◽  
Apiwat Chompoosor ◽  
Somdej Kanokmedhakul ◽  
Saowapak Teerasong
Keyword(s):  
Gold Nanoparticles ◽  
Uv Irradiation ◽  
Irradiation Time ◽  
Spherical Shape ◽  
Average Diameter ◽  
Drug Carriers ◽  
Hydrophobic Core ◽  
Triggered Release ◽  
Hydrophobic Molecule ◽  
Positively Charged Gold Nanoparticle

The results of releasing a drug in a burst are unpredictable and one of the inherent drawbacks of using nanocarriers. Here, photoresponsive cationic gold nanoparticles to stabilize diacetylenic nanocapsules enabling photoregulated release of payloads are reported. The fabrication of these nanocapsules relied on an electrostatic interaction of a negatively charged diacetylenic core and a positively charged gold nanoparticle shell. Gold nanoparticles with photoresponsive ligands on their surfaces act as both hydrophobic core stabilizers and gatekeepers of the nanocapsules, while their polydiacetylene cores serve as hydrophobic drug carriers that can be tuned using UV irradiation. The morphology of nanocapsules was analyzed using TEM and dynamic light scattering. The resultant nanocapsules had a spherical shape with an average diameter of 152.9 ± 6.7 nm. Upon UV irradiation, the nanocapsules lost their integrity and an encapsulated model compound was released through diffusion. The release of a hydrophobic molecule was irradiation time dependent and thereby controllable. This light-triggered release provides an alternative strategy for controlled drug delivery.

Reflection technique in time‐frequency domain using multicomponent acoustic emission signals and application to geothermal reservoirs

Geophysics ◽  
2002 ◽  
Vol 67 (3) ◽  
pp. 928-938 ◽  
Author(s):  
Nobukazu Soma ◽  
Hiroaki Niitsuma ◽  
Roy Baria
Keyword(s):  
Acoustic Emission ◽  
Wavelet Transform ◽  
Frequency Domain ◽  
Random Noise ◽  
Spherical Shape ◽  
Source Distribution ◽  
S Wave ◽  
Spectral Matrix ◽  
Time Frequency ◽  
Reflected Wave

We have developed a reflection technique for estimating deep geothermal reservoir structures using acoustic emission signals as a source, which is useful when there is no proper estimating technique because of high temperature, high pressure, and great depth. Because its resolution is not high enough for comparison with methods such as well logging, we have enhanced the technique by developing a time–frequency‐domain analysis of multicomponent acoustic emission signals using a wavelet transform. The reflected wave is separated from an incoherent coda by analyzing the shape of a 3‐D hodogram: a linear shape indicates the arrival of a coherent signal such as a reflected wave, and an incoherent signal such as a coda makes a spherical shape. We construct a spectral matrix of 3‐D particle motion using a wavelet transform, as is done in a time–frequency domain. We evaluate the linearity of the 3‐D hodogram for each time and frequency by using the eigenvalues of the spectral matrix. Three‐dimensional inversion of the distribution of hodogram linearity in the time–frequency domain lets us image the deep subsurface structure. The inversion is based on the diffraction stack. We reduce the uncertainties by investigating S‐wave polarization direction, and we compensate for inhomogeneous source distribution to get reliable estimates with high resolution. We then evaluate our methods with synthetic signals. We discriminate a coherent wave from incoherent random noise in the presence of an S/N ratio of −3.7 dB and detect reflectors at correct depths with a small number of detectors. We apply the method to data from the European hot, dry rock site in Soultz‐sous‐Forêts, France, and compare our estimates with those from a number of borehole observations. The detected reflectors agree with the location of fracture zones. We demonstrate the feasibility of the method for detecting reflectors at great depths.

scholarly journals The Toxic Effect of Pb Nanoparticles Prepared by Laser ablation on Some Biochemical Aspects in Rats

2021 ◽  
Vol 19 (48) ◽  
pp. 107-114
Author(s):  
Fiham Jasim Alobaidi ◽  
Abid A. Thaker ◽  
Asmiet Ramizy
Keyword(s):  
Laser Ablation ◽  
Characteristic Feature ◽  
Toxic Effect ◽  
Serum Proteins ◽  
Spherical Shape ◽  
Average Diameter ◽  
Total Serum Protein ◽  
Total Serum ◽  
Pure Lead ◽  
Experimental Animals

This work aimed to prepare and study the characteristic feature of lead nanoparticles (PbNPS) and follow its effects on some physiological aspects in rats.PbNPS was prepared by laser ablation of pure lead mass with a pulse of 500 and 100 mJ of energy. The results indicated that the wavelength was approximately 196 and the concentration was reported at 53,8967 mg / L. AFM, as the average diameter has been estimated at 69.93 nm. EFSEM shows the spherical shape of the particle.The experimental animals (rats) were divided into two groups, with seven rats for each one. The first group was a control and the second group was injected with 1 milliliter of PbNPS (53.8673 mg/l) per day for 45 days. Bioaccumulated lead ( in liver, spleen kidney and muscles), total serum proteins, albumin, ALT, AST, ALP and antioxidants (GSH, SOD, CAT, and MDA) were estimated.By comparison to the control, PbNPS exposed animals. There were no significant differences in the bioaccumulated lead. In contrast, there was a significant reduction in total serum protein, albumin, GSH, SOD, CAT. Also, there was an increase in serum ALT, AST, ALP and MDA.

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