Search results for: dielectric scattering

Authors: Yazid Alkraimeen

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Precise prediction of dielectric stresses and high voltages of power transformers require the accurate calculation of frequency-dependent parameters. A lack of accuracy can result in severe damages to transformer windings. Transient conditions is stuided by digital computers, which require the implementation of accurate models. This paper analyzes the computation of frequency-dependent skin and proximity losses included in the transformer winding model, using analytical equations and Finite Element Method (FEM). A modified formula to calculate the proximity and the skin losses is presented. The results of the frequency-dependent parameter calculations are verified using the Finite Element Method. The time-domain transient voltages are obtained using Numerical Inverse Laplace Transform. The results show that the classical formula for proximity losses is overestimating the transient voltages when compared with the results obtained from the modified method on a simple transformer geometry.

Keywords: fast front transients, proximity losses, transformer winding modeling, skin losses

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Authors: Fernando G. Torres, Omar P. Troncoso

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Starch is a highly biocompatible, non-toxic, and biodegradable polymer. It is widely used in biomedical applications, including drug delivery systems and tissue engineering scaffolds. Curcumin, a phenolic compound found in the dried root of Curcuma longa, has been used as a nutritional supplement due to its antimicrobial, anti-inflammatory, and antioxidant effects. However, the major problem with ingesting curcumin by itself is its poor bioavailability due to its poor absorption and rapid metabolism. In this study, we report a novel methodology to prepare starch nanoparticles loaded with curcumin. The nanoparticles were synthesized via nanoprecipitation of starch granules extracted from native Andean potatoes (Solanum tuberosum ssp. and Andigena var Huamantanga varieties). The nanoparticles were crosslinked and stabilized by using sodium tripolyphosphate and Tween®80, respectively. The characterization of the nanoparticles loaded with curcumin was assessed by Fourier Transform Infrared Spectroscopy, Dynamic Light Scattering, Zeta potential, and Differential scanning calorimetry. UV-vis spectrophotometry was used to evaluate the loading efficiency and capacity of the samples. The results showed that native starch nanoparticles could be used to prepare promising nanocarriers for the controlled release of curcumin.

Keywords: starch nanoparticle, nanoprecipitation, curcumin, biomedical applications

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Authors: Bireswar Paul, Amitava Datta

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Indoor air environment is a big concern in the last few decades in the developing countries, with increased focus on monitoring the air quality. In this work, an experimental study has been conducted to establish the existence of carbon nanoparticles below the size range of 10 nm in the non-sooting zone of a LPG/air partially premixed flame. Mainly, four optical techniques, UV absorption spectroscopy, fluorescence spectroscopy, dynamic light scattering and TEM have been used to characterize and measure the size of carbon nanoparticles in the sampled materials collected from the inner surface of the flame front. The existence of the carbon nanoparticles in the sampled material has been confirmed with the typical nature of the absorption and fluorescence spectra already reported in the literature. The band gap energy shows that the particles are made up of three to six aromatic rings. The size measurement by DLS technique also shows that the particles below the size range of 10 nm. The results of DLS are also corroborated by the TEM image of the same material. 

Keywords: indoor air, carbon nanoparticle, lpg, partially premixed flame, optical techniques

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Authors: Ishraq M. Anjum

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Distributed Bragg reflectors are used in vertical-cavity surface-emitting lasers (VCSELs) in order to achieve very high reflectivity. Use of metamaterial in place of distributed Bragg reflector can reduce the device size significantly. A silicon-based metamaterial near perfect reflector is designed to be used in place of distributed Bragg reflectors in VCSELs. Mie resonance in dielectric microparticles is exploited in order to design the metamaterial. A reflectivity of 98.31% is achieved using finite-difference time-domain method. An 808nm double intra-cavity contacted VCSEL structure with 1.5 λ cavity is proposed using this metamaterial near perfect reflector. The active region is designed to be composed of seven GaAs/AlGaAs quantum wells. Upon numerical investigation of the designed VCSEL structure, the threshold current is found to be 2.96 mA at an aperture of 40 square micrometers and the maximum output power is found to be 71 mW at a current of 141 mA. Miniaturization of conventional VCSELs is possible using this design.

Keywords: GaAs, LASER, metamaterial, VCSEL, vertical cavity surface emitting laser

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Authors: N. Q. Bau, N. V. Nghia

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The acoustomagnetoelectric (AME) field in a rectangular quantum wire with an infinite potential (RQWIP) is calculated in the presence of an external magnetic field (EMF) by using the quantum kinetic equation for the distribution function of electrons system interacting with external phonons and electrons scattering with internal acoustic phonon in a RQWIP. We obtained ananalytic expression for the AME field in the RQWIP in the presence of the EMF. The dependence of AME field on the frequency of external acoustic wave, the temperature T of system, the cyclotron frequency of the EMF and the intensity of the EMF is obtained. Theoretical results for the AME field are numerically evaluated, plotted and discussed for a specific RQWIP GaAs/GaAsAl. This result has shown that the dependence of the AME field on intensity of the EMF is nonlinearly and it is many distinct maxima in the quantized magnetic region. We also compared received fields with those for normal bulk semiconductors, quantum well and quantum wire to show the difference. The influence of an EMF on AME field in a RQWIP is newly developed.

Keywords: rectangular quantum wire, acoustomagnetoelectric field, electron-phonon interaction, kinetic equation method

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Authors: Mojtaba Farzaneh, Majid Baghaei Nejad

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This article proposes a new Flexible Capacitive Tactile Sensors based on paper sheets. This method combines the parameters of sensor's material and dielectric, and forms a new model of flexible capacitive sensors. The present article tries to present a practical explanation of this method's application and advantages. With the use of this new method, it is possible to make a more flexibility and accurate sensor in comparison with the current models. To assess the performance of this model, the common capacitive sensor is simulated and the proposed model of this article and one of the existing models are assessed. The results of this article indicate that the proposed model of this article can enhance the speed and accuracy of tactile sensor and has less error in comparison with the current models. Based on the results of this study, it can be claimed that in comparison with the current models, the proposed model of this article is capable of representing more flexibility and more accurate output parameters for touching the sensor, especially in abnormal situations and uneven surfaces, and increases accuracy and practicality.

Keywords: capacitive sensor, paper sheets, flexible, tactile, uneven

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Authors: Omaima G. Allam, O. A. Hakeim, K. Haggag, N. S. Elshemy

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In the midst of the two decades the use of microwave dielectric warming in the field of science has transformed into a powerful methodology to redesign compound procedures. The potential benefit of the application of these modern methods of treatment emphasize so as to reach to optimum treatment conditions and the best results, especially hydrophobicity, moisture content and increase dyeing processing while maintaining the physical and chemical properties of each textile. Moreover, polyester fibres are sometimes spun together with natural fibres to produce a cloth with blended properties. So that at the present task, the polyester/viscose mix fabrics (60 /40) were pretreated with 4 g/l of KOH for 2 min in microwave irradiation with a liquor ratio 1:25. Subsequently fabrics were inundated with different concentrations of sericin (10, 30, 50 g/l). Treated fabrics were coloured with the commercial dyes samples: Reactive Red 84(Dye 1). C. I. Acid Blue 203(Dye 2) and C.I. Reactive violet 5 (Dye 3). Colour value was specified as well as fastness properties. Likewise, the physical properties of untreated and treated fabrics such as moisture content %, tensile strength, elongation % and were evaluated. The untreated and treated fabrics are described by infrared spectroscopy (FTIR) and scanning electron microscopy.

Keywords: polyester viscose blends fabric, sericin, dyes, colour value

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Authors: Alireza Derambakhsh

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The objective of this examination is to explore the capability of utilizing Google Earth for Internet GIS applications. The study particularly analyzes the utilization of vector and characteristic information and the capability of showing and preparing this information in new ways utilizing the Google Earth stage. It has progressively been perceived that future improvements in GIS will fixate on Internet GIS, and in three noteworthy territories: GIS information access, spatial data scattering and GIS displaying/preparing. Google Earth is one of the group of geobrowsers that offer a free and simple to utilize administration that empower information with a spatial part to be overlain on top of a 3-D model of the Earth. This examination makes a methodological structure to accomplish its objective that comprises of three noteworthy parts: A database level, an application level and a customer level. As verification of idea a web model has been produced, which incorporates a differing scope of datasets and lets clients direst inquiries and make perceptions of this custom information. The outcomes uncovered that both vector and property information can be successfully spoken to and imagined utilizing Google Earth. In addition, the usefulness to question custom information and envision results has been added to the Google Earth stage.

Keywords: Google earth, internet GIS, vector, characteristic information

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Authors: Chejarla Raghunathababu, E. Logashanmugam

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An antenna is an assortment of linked devices that function together to transmit and receive radio waves as a single antenna. Antennas occur in a variety of sizes and forms, but the microstrip patch antenna outperforms other types in terms of effectiveness and prediction. These antennas are easy to generate with discreet benefits. Nevertheless, the antenna's effectiveness will be affected because of the patch's shape above a thick dielectric substrate. As a result, a double-pole rectangular microstrip antenna with nanofillers was suggested in this study. By employing nano-composite substances (Fumed Silica and Aluminum Oxide), which are composites of graphene with nanofillers, the physical characteristics of the microstrip antenna, that is, the elevation of the microstrip antenna substrate and the width of the patch microstrip antenna have been improved in this research. The surface conductivity of graphene may be modified to function at specific frequencies. In order to prepare for future wireless communication technologies, a microstrip patch antenna operating at 93 GHz resonant frequency is constructed and investigated. The goal of this study was to reduce VSWR and increase gain. The simulation yielded results for the gain and VSWR, which were 8.26 dBi and 1.01, respectively.

Keywords: graphene, microstrip patch antenna, substrate material, wireless communication, nanocomposite material

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Authors: Saleem Rao, Mohammed Al-Ghadeer, Archan Banerjee, Hossein Fariborzi

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Materials imperfection, particularly two-level-system (TLS) defects in planer superconducting quantum circuits, contributes significantly to decoherence, ultimately limiting the performance of quantum computation and sensing. Oxides at air interfaces are among the host of TLS, and different material has been used to reduce TLS losses. Passivation with an inorganic layer is not an option to reduce these interface oxides; however, they can be etched away, but their regrowth remains a problem. Here, we report the chemisorption of molecular self-assembled monolayers (SAMs) at air interfaces of superconducting co-planer waveguide (CPW) resonators that suppress the regrowth of oxides and also modify the dielectric constant of the interface. With SAMs, we observed sustained order of magnitude improvement in quality factor -better than oxide etched interfaces. Quality factor measurements at millikelvin temperature and at single photon, XPS data, and TEM images of SAM passivated air interface sustenance our claim. Compatibility of SAM with micro-/nano-fabrication processes opens new ways to improve the coherence time in cQED.

Keywords: superconducting circuits, quality-factor, self-assembled monolayer, coherence

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Authors: Chaluntorn Vichasilp, Sutee Wangtueai

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This study aims to develop a new method to detect active compounds in Thai herbs (1-deoxynojirimycin (DNJ) in mulberry leave, anthocyanin in Mao and curcumin in turmeric) using near infrared spectroscopy (NIRs). NIRs is non-destructive technique that rapid, non-chemical involved and low-cost determination. By NIRs and chemometrics technique, it was found that the DNJ prediction equation conducted with partial least square regression with cross-validation had low accuracy R2 (0.42) and SEP (31.87 mg/100g). On the other hand, the anthocyanin prediction equation showed moderate good results (R2 and SEP of 0.78 and 0.51 mg/g) with Multiplication scattering correction at wavelength of 2000-2200 nm. The high absorption could be observed at wavelength of 2047 nm and this model could be used as screening level. For curcumin prediction, the good result was obtained when applied original spectra with smoothing technique. The wavelength of 1400-2500 nm was created regression model with R2 (0.68) and SEP (0.17 mg/g). This model had high NIRs absorption at a wavelength of 1476, 1665, 1986 and 2395 nm, respectively. NIRs showed prospective technique for detection of some active compounds in Thai herbs.

Keywords: anthocyanin, curcumin, 1-deoxynojirimycin (DNJ), near infrared spectroscopy (NIRs)

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Authors: M. Y. Ismail, M. Inam

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This paper presents the design and analysis of Liquid Crystal (LC) based tunable reflect array antenna with different design configurations within X-band frequency range. The effect of LC volume used for unit cell element on frequency tunability and reflection loss performance has been investigated. Moreover different slot embedded patch element configurations have been proposed for LC based tunable reflect array antenna design with enhanced performance. The detailed fabrication and measurement procedure for different LC based unit cells has been presented. The waveguide scattering parameter measured results demonstrated that by using the circular slot embedded patch elements, the frequency tunability and dynamic phase range can be increased from 180 MHz to 200 MHz and 120° to 124° respectively. Furthermore the circular slot embedded patch element can be designed at 10 GHz resonant frequency with a patch volume of 2.71 mm3 as compared to 3.47 mm3 required for rectangular patch without slot.

Keywords: liquid crystal, tunable reflect array, frequency tunability, dynamic phase range

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Authors: Kasra Khorsand-Kazemi, Bianca Vizcaino, Mandeep Chhajer Jain, Maryam Moradpour

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This work presents an approach to characterize a non- contact microwave sensor using waveguides for different standard liquids such as ethanol, methanol and 2-propanol (Isopropyl Alcohol). Wideband waveguides operating between 12.4GHz to 18 GHz form the core of the sensing structure. Waveguides are sensitive to changes in conductivity of the sample under test (SUT), making them an ideal tool to characterize different polar liquids. As conductivity of the sample under test increase, the loss tangent of the material increase, thereby decreasing the S21 (dB) response of the waveguide. Among all the standard liquids measured, methanol exhibits the highest conductivity and 2-Propanol exhibits the lowest. The cutoff frequency measured for ethanol, 2-propanol, and methanol are 10.28 GHz, 10.32 GHz, and 10.38 GHz respectively. The measured results can be correlated with the loss tangent results of the standard liquid measured using the dielectric probe. This conclusively enables us to characterize different liquids using waveguides expanding the potential future applications in domains ranging from water quality management to bio-medical, chemistry and agriculture.

Keywords: Waveguides, , Microwave sensors, , Standard liquids characterization, Non-contact sensing

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Authors: Chandrashekar, R. T. Radhika, B. M. Venkatesha, S. Ananda, Shivalingegowda, T. S. Shashikumar, H. Ramachandra

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The kinetics of the oxidation of amitriptyline (AT) by sodium N-bromotoluene sulphonamide (C₆H₅SO₂NBrNa) has been studied in an acidic buffer medium of pH 1.2 at 303 K. The oxidation reaction of AT was followed spectrophotometrically at maximum wavelength, 410 nm. The reaction rate shows a first order dependence each on concentration of AT and concentration of sodium N-bromotoluene sulphonamide. The reaction also shows an inverse fractional order dependence at low or high concentration of HCl. The dielectric constant of the solvent shows negative effect on the rate of reaction. The addition of halide ions and the reduction product of BAT have no significant effect on the rate. The rate is unchanged with the variation in the ionic strength (NaClO₄) of the medium. Addition of reaction mixtures to be aqueous acrylamide solution did not initiate polymerization, indicating the absence of free radical species. The stoichiometry of the reaction was found to be 1:1 and oxidation product of AT is identified. The Michaelis-Menton type of kinetics has been proposed. The CH₃C₆H₅SO₂NHBr has been assumed to be the reactive oxidizing species. Thermodynamical parameters were computed by studying the reactions at different temperatures. A mechanism consistent with observed kinetics is presented.

Keywords: amitriptyline, bromamine-T, kinetics, oxidation

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Authors: Van Tran Thi Thuy, Cheol Won Lim, Dukjoon Kim

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A series of biodegradable copolymers based on polyaspartamide (PASPAM) were synthesized by grafting hydrophilic O-(2-aminoethyl)-O'-methylpoly(ethylene glycol) (MPEG), hydrophobic cholic acid (CA), and pH-sensitive hydrazine (Hyd) segments on a PASPAM backbone. The hydrazine group was effectively cleaved to release doxorubicin (DOX) conjugated on PASPAM in an acidic environment. The chemical structure of the polymer and the degree of substitution of each graft segment were analyzed using FT-IR and 1H-NMR spectroscopy. The size of the MPEG/Hyd/CA-g-PASPAM copolymer self-aggregates was examined by dynamic light scattering (DLS) and transmission electron microscope (TEM). The mean diameter of the self - aggregates increased from 125 to 200 nm at pH 7.4, as the degree of substitution of CA increased from 10 to 20 %. The release kinetics of DOX was strongly affected by the pH of the releasing medium. While less than 30% of the DOX-loaded was released in about 30 h at pH 7.4, more than 60% was released at pH 5.0 within the same time. The viability tests of human breast cancer cells (MCF-7) and human embryonic kidney cells (293T) show the potential application of MPEG/Hyd/CA-g-PASPAM copolymer self-aggregates in the controlled intracellular delivery for cancer treatments.

Keywords: pH-sensitive, drug delivery, polyaspartamide, self-assembly, nano-aggregates

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Authors: Karkour Selma

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We conducted first principles full potential calculations using the Wien2k code to explore the structural, electronic, magnetic, and optical properties of SiNi₂O₄, a cubic normal spinel oxide. Our calculations, based on the GGA-PBEsol of the generalized gradient approximation, revealed several key findings. The spinel oxides exhibited a stable cubic structure in the ferromagnetic phase and showed 100% spin polarization. We determined the equilibrium lattice constant and internal parameter values. In terms of the electronic properties, we observed a direct bandgap of 2.68 eV for the spin-up configuration, while the spin-down configuration exhibited an indirect bandgap of 0.82 eV. Additionally, we calculated the total density of states and partial densities for each atom, finding a magnetic moment spin density of states of 8.0 μB per formula unit. The optical properties have been calculated. The real, Ԑ₁(ω) and the imaginary, Ԑ₂(ω) parts of the complex dielectric constants, refractivity, reflection and energy loss when light scattered from the material. The absorption region spanned from 1.5 eV to 14 eV, with significant intensity. The calculated results confirm the suitability of this material for optical and spintronic devices application.

Keywords: DFT, spintronic, GGA, spinel

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Authors: Manoj Kumar

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Ionization cross sections of molecules due to electron impact play an important role in chemical processes in various branches of applied physics, such as radiation chemistry, gas discharges, plasmas etching in semiconductors, planetary upper atmospheric physics, mass spectrometry, etc. In the present work, we have calculated the total ionization cross sections for Adenine (C₅H₅N₅), a biologically important molecule, by electron impact in the incident electron energy range from ionization threshold to 2 keV employing a well-known Jain-Khare semiempirical formulation based on Bethe and Möllor cross sections. In the non-availability of the experimental results, the present results are in good agreement qualitatively as well as quantitatively with available theoretical results. The present results drive our confidence for further investigation of complex bio-molecule with better accuracy. Notwithstanding, the present method can deduce reliable cross-sectional data for complex targets with adequate accuracy and may facilitate the acclimatization of calculated cross-sections into atomic molecular cross-section data sets for modeling codes and other applications.

Keywords: electron impact ionization cross-sections, oscillator strength, jain-khare semiempirical approach

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Authors: Yousif Mohamed Y. Abdallah, Eltayeb Wagallah

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Image enhancement allows the observer to see details in images that may not be immediately observable in the original image. Image enhancement is the transformation or mapping of one image to another. The enhancement of certain features in images is accompanied by undesirable effects. To achieve maximum image quality after denoising, a new, low order, local adaptive Gaussian scale mixture model and median filter were presented, which accomplishes nonlinearities from scattering a new nonlinear approach for contrast enhancement of bones in bone scan images using both gamma correction and negative transform methods. The usual assumption of a distribution of gamma and Poisson statistics only lead to overestimation of the noise variance in regions of low intensity but to underestimation in regions of high intensity and therefore to non-optional results. The contrast enhancement results were obtained and evaluated using MatLab program in nuclear medicine images of the bones. The optimal number of bins, in particular the number of gray-levels, is chosen automatically using entropy and average distance between the histogram of the original gray-level distribution and the contrast enhancement function’s curve.

Keywords: bone scan, nuclear medicine, Matlab, image processing technique

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Authors: Olga Długosz, Jolanta Pulit-Prociak, Marcin Banach

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The paper presents a process to obtain glutathione-modified titanium oxide nanoparticles. The processes were carried out in a microwave radiation field. The influence of the molar ratio of glutathione to titanium oxide and the effect of the fold of NaOH vs. stoichiometric amount on the size of the formed TiO₂ nanoparticles was determined. The physicochemical properties of the obtained products were evaluated using dynamic light scattering (DLS), transmission electron microscope- energy-dispersive X-ray spectroscopy (TEM-EDS), low-temperature nitrogen adsorption method (BET), X-Ray Diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) microscopy methods. The size of TiO₂ nanoparticles was characterized from 30 to 336 nm. The release of titanium ions from the prepared products was evaluated. These studies were carried out using different media in which the powders were incubated for a specific time. These were water, SBF and Ringer's solution. The release of titanium ions from modified products is weaker compared to unmodified titanium oxide nanoparticles. The reduced release of titanium ions may allow the use of such modified materials as substances in drug delivery systems.

Keywords: titanium dioxide, nanoparticles, drug carrier, glutathione

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Authors: Olga Długosz, Jolanta Pulit-Prociak, Marcin Banach

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The paper presents a process to obtain glutathione-modified titanium oxide nanoparticles. The processes were carried out in a microwave radiation field. The influence of the molar ratio of glutathione to titanium oxide and the effect of the fold of NaOH vs. stoichiometric amount on the size of the formed TiO₂ nanoparticles was determined. The physicochemical properties of the obtained products were evaluated using dynamic light scattering (DLS), transmission electron microscope- energy-dispersive X-ray spectroscopy (TEM-EDS), low-temperature nitrogen adsorption method (BET), X-Ray Diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) microscopy methods. The size of TiO₂ nanoparticles was characterized from 30 to 336 nm. The release of titanium ions from the prepared products was evaluated. These studies were carried out using different media in which the powders were incubated for a specific time. These were: water, SBF, and Ringer's solution. The release of titanium ions from modified products is weaker compared to unmodified titanium oxide nanoparticles. The reduced release of titanium ions may allow the use of such modified materials as substances in drug delivery systems.

Keywords: titanium dioxide, nanoparticles, drug carrier, glutathione

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Authors: Mor Diama L. O., Matthieu Davy, Laurent Ferro-Famil

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In this article, inverse synthetic aperture radar (ISAR) is combined with compressive imaging techniques in order to perform 3D interferometric imaging. Interferometric ISAR (InISAR) imaging relies on a two-dimensional antenna array providing diversities in the elevation and azimuth directions. However, the signals measured over several antennas must be acquired by coherent receivers resulting in costly and complex hardware. This paper proposes to use a chaotic cavity as a compressive device to encode the signals arising from several antennas into a single output port. These signals are then reconstructed by solving an inverse problem. Our approach is demonstrated experimentally with a 3-elements L-shape array connected to a metallic compressive enclosure. The interferometric phases estimated from a unique broadband signal are used to jointly estimate the target’s effective rotation rate and the height of the dominant scattering centers of our target. Our experimental results show that the use of the compressive device does not adversely affect the performance of our imaging process. This study opens new perspectives to reduce the hardware complexity of high-resolution ISAR systems.

Keywords: interferometric imaging, inverse synthetic aperture radar, compressive device, computational imaging

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Authors: Purnima Rawat, Divya Vohora, Sarika Gupta, Farhan J. Ahmad, Sushama Talegaonkar

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Nanoparticles (NPs) that target bone tissue were developed using PLGA–mPEG (poly(lactic-co-glycolic-acid)–polyethylene glycol) diblock copolymers by using pamidronate as a bone-targeting moieties. These NPs are expected to enable the transport of hydrophilic drugs. The NP was prepared by in situ polymerization method, and their in- vitro characteristics were evaluated using dynamic light scattering, transmission electron microscopy (TEM) and in phosphate-buffered solution. The bone targeting potential of the NP was also evaluated on in-vitro pre-osteoblast MCT3E1 cell line using ALP activity, degree of mineralization and RT-PCR assay. The average particle size of the NP was 101.6 ± 3.7nm, zeta potential values were negative (-25±0.34mV) of the formulations and the entrapment efficiency was 93± 3.1 % obtained. The moiety of the PLGA–mPEG–pamidronate NPs exhibited the best apatite mineral binding ability in-vitro MCT3E1 pre-osteoblast cell line. Our results suggested that the developed nanoparticles may use as a delivery system for Pamidronate in bone repair and regeneration, warranting further evaluation of the treatment of bone disease.

Keywords: nanoparticle, pamidronate, in-situ polymerization, osteoblast

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Authors: Pravin Gaikwad, Prakash Mahanwar

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The main objective of incorporating natural fibers such as Henequen microfibers (NF) into the High-Density Polyethylene (HDPE) polymer matrix is to reduce the cost and to enhance the mechanical as well as other properties. The Henequen microfibers were chopped manually to 5-7mm in length and added into the polymer matrix at the optimized concentration of 8 wt %. In order to facilitate the link between Henequen microfibers (NF) and HDPE matrix, coupling agent such as Glycidoxy (Epoxy) Functional Methoxy Silane (GPTS) at various concentrations from 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, and 1% by weight to the total fibers were added. The tensile strength of the composite increased marginally while % elongation at break of the composites decreased with increase in silane loading by wt %. Tensile modulus and stiffness observed increased at 0.9 wt % GPTS loading. Flexural as well as impact strength of the composite decreased with increase in GPTS loading by weight %. Dielectric strength of the composite also found increased marginally upto 0.5wt % silane loading and thereafter remained constant.

Keywords: Henequen microfibers (NF), polymer composites, HDPE, coupling agent, GPTS

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Authors: Shiraz A. Markarian

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Our systematic studies of diethylsulfoxide (DESO), the nearest homologue of dimethylsulfoxide (DMSO), reveal new physicochemical features. DESO has already received worthy biomedical applications: in some cases even are more pronounced compare with DMSO. The several important physicochemical characteristics of DESO including aqueous solutions have been verified and first reported: melting point of pure substance, density, dielectric relaxation data, vapor pressure and volumetric properties. Analysis of the complete vibrational spectra also leads to the conclusion that very strong interactions take place between DESO and water, even stronger than those between DMSO and water. The simultaneous existence of strong DESO-H₂O and DESO-DESO interactions suggest the coexistence of many types of structural molecular aggregates, the presence of which plays a significant role also in diluted water solutions. Our recent investigations have shown that aqueous solution of DESO could provide amorphous, glassy systems, thus avoiding ice crystallization, in a wide range of concentrations and even at very low cooling rates. The ability of DESO to act as an effective cryoprotectant on E. coli survival was also studied and compared with other commonly used cryoprotective agents. The results also confirm that DESO, more than DMSO, is able to penetrate living tissues without causing significant damage.

Keywords: diethylsulfoxide, dimethylsulfoxide, cryoprotectant, properties

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Authors: Mohammad Alenezi

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Hierarchical nanostructures with higher dimensionality, consisting of nanostructure building blocks such as nanowires, nanotubes, or nanosheets are very attractive. They hold great properties like the high surface-to-volume ratio and well-ordered porous structures, which can be very challenging to attain for other mono-morphological nanostructures. Well-ordered hierarchical nanostructures with high surface-to-volume ratios facilitate gas diffusion into their surfaces as well as scattering of light. Therefore, hierarchical nanostructures are expected to perform highly as gas sensors. A multistage controlled hydrothermal synthesis method to fabricate high-performance single ZnO brushlike hierarchical nanostructure gas sensor from initial nanowires is reported. The performance of the sensor based on brush-like hierarchical nanostructure is analyzed and compared to that of a nanowire gas sensor. The hierarchical gas sensor demonstrated high sensitivity toward low concentration of acetone at high speed of response. The enhancement in the hierarchical sensor performance is attributed to the increased surface to volume ratio, reduction in dimensionality of the nanowire building blocks, formation of junctions between the initial nanowire and the secondary nanowires, and enhanced gas diffusion into the surfaces of the hierarchical nanostructures.

Keywords: metal oxide, nanostructure, hydrothermal, sensor

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Authors: M. Kumpugdee-Vollrath, J.-P. Krause, S. Bürk

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Most of the drugs used for pharmaceutical purposes are poorly water-soluble drugs. About 40% of all newly discovered drugs are lipophilic and the numbers of lipophilic drugs seem to increase more and more. Drug delivery systems such as nanoparticles, micelles or liposomes are applied to improve their solubility and thus their bioavailability. Besides various techniques of solubilization, oil-in-water emulsions are often used to incorporate lipophilic drugs into the oil phase. To stabilize emulsions surface active substances (surfactants) are generally used. An alternative method to avoid the application of surfactants was of great interest. One possibility is to develop O/W-emulsion without any addition of surface active agents or the so called “surfactant-free emulsion or SFE”. The aim of this study was to develop and characterize SFE as a drug carrier by varying the production conditions. Lidocaine base was used as a model drug. The injection method was developed. Effects of ultrasound as well as of temperature on the properties of the emulsion were studied. Particle sizes and release were determined. The long-term stability up to 30 days was performed. The results showed that the surfactant-free O/W emulsions with pharmaceutical oil as drug carrier can be produced.

Keywords: emulsion, lidocaine, Miglyol, size, surfactant, light scattering, release, injection, ultrasound, stability

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Authors: Pradeep Lamichhane, Nima Pourali, E. V. Rebrov, Volker Hessel

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Nitrogen fixation is critical for plants for the biosynthesis of protein and nucleic acid. Most of our atmosphere is nitrogen, yet plants cannot directly absorb it from the air, and natural nitrogen fixation is insufficient to meet the demands. This experiment used a fast-modulated surface-confined atmospheric pressure plasma created by a 6 kV (peak-peak) sinusoidal power source with a repetition frequency of 68 kHz to fix nitrogen. Plasmas have been proposed for excitation of nitrogen gas, which quickly oxidised to NOX. With different N2/O2 input ratios, the rate of NOX generation was investigated. The rate of NOX production was shown to be optimal for mixtures of 60–70% O2 with N2. To boost NOX production in plasma, metal oxide catalysts based on TiO2 were coated over the dielectric layer of a reactor. These results demonstrate that nitrogen activation was more advantageous in surface-confined plasma sources because micro-discharges formed on the sharp edges of the electrodes, which is a primary function attributed to NOX synthesis and is further enhanced by metal oxide catalysts. The energy-efficient and sustainable NOX synthesis described in this study will offer a fresh perspective for ongoing research on green nitrogen fixation techniques.

Keywords: nitrogen fixation, fast-modulated, surface-confined, sustainable

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Authors: Utkarsh A. Mishra, Ankit Bansal

Abstract:

At high temperature, radiative heat transfer is the dominant mode of heat transfer. It is governed by various phenomena such as photon emission, absorption, and scattering. The solution of the governing integrodifferential equation of radiative transfer is a complex process, more when the effect of participating medium and wavelength properties are taken into consideration. Although a generic formulation of such radiative transport problem can be modeled for a wide variety of problems with non-gray, non-diffusive surfaces, there is always a trade-off between simplicity and accuracy of the problem. Recently, solutions of complicated mathematical problems with statistical methods based on randomization of naturally occurring phenomena have gained significant importance. Photon bundles with discrete energy can be replicated with random numbers describing the emission, absorption, and scattering processes. Photon Monte Carlo (PMC) is a simple, yet powerful technique, to solve radiative transfer problems in complicated geometries with arbitrary participating medium. The method, on the one hand, increases the accuracy of estimation, and on the other hand, increases the computational cost. The participating media -generally a gas, such as CO₂, CO, and H₂O- present complex emission and absorption spectra. To model the emission/absorption accurately with random numbers requires a weighted sampling as different sections of the spectrum carries different importance. Importance sampling (IS) was implemented to sample random photon of arbitrary wavelength, and the sampled data provided unbiased training of MC estimators for better results. A better replacement to uniform random numbers is using deterministic, quasi-random sequences. Halton, Sobol, and Faure Low-Discrepancy Sequences are used in this study. They possess better space-filling performance than the uniform random number generator and gives rise to a low variance, stable Quasi-Monte Carlo (QMC) estimators with faster convergence. An optimal supervised learning scheme was further considered to reduce the computation costs of the PMC simulation. A one-dimensional plane-parallel slab problem with participating media was formulated. The history of some randomly sampled photon bundles is recorded to train an Artificial Neural Network (ANN), back-propagation model. The flux was calculated using the standard quasi PMC and was considered to be the training target. Results obtained with the proposed model for the one-dimensional problem are compared with the exact analytical and PMC model with the Line by Line (LBL) spectral model. The approximate variance obtained was around 3.14%. Results were analyzed with respect to time and the total flux in both cases. A significant reduction in variance as well a faster rate of convergence was observed in the case of the QMC method over the standard PMC method. However, the results obtained with the ANN method resulted in greater variance (around 25-28%) as compared to the other cases. There is a great scope of machine learning models to help in further reduction of computation cost once trained successfully. Multiple ways of selecting the input data as well as various architectures will be tried such that the concerned environment can be fully addressed to the ANN model. Better results can be achieved in this unexplored domain.

Keywords: radiative heat transfer, Monte Carlo Method, pseudo-random numbers, low discrepancy sequences, artificial neural networks

Procedia PDF Downloads 207

Authors: F. J. Puertas, M. Castro, A. Tebar, P. J. Fito, R. Gadea, J. M. Monzó, R. J. Colom

Abstract:

There is a great diversity of diseases that affect the integrity of the walls of the esophagus, generally of a digestive nature. Among them, gastroesophageal reflux is a common disease in the general population, affecting the patient's quality of life; however, there are still unmet diagnostic and therapeutic issues. The consequences of untreated or asymptomatic acid reflux on the esophageal mucosa are not only pain, heartburn, and acid regurgitation but also an increased risk of esophageal cancer. Currently, the diagnostic methods to detect problems in the esophageal tract are invasive and annoying, as 24-hour impedance-pH monitoring forces the patient to be uncomfortable for hours to be able to make a correct diagnosis. In this work, the development of a sensor able to measure in depth is proposed, allowing the detection of liquids circulating in the esophageal tract. The multisensor detection system is based on radiofrequency photospectrometry. At an experimental level, consumers representative of the population in terms of sex and age have been used, placing the sensors between the trachea and the diaphragm analyzing the measurements in vacuum, water, orange juice and saline medium. The results obtained have allowed us to detect the appearance of different liquid media in the esophagus, segregating them based on their ionic content.

Keywords: bioimpedance, dielectric spectroscopy, gastroesophageal reflux, GERD

Procedia PDF Downloads 83

Authors: Lourena M. Veríssimo, Lucas A. Machado, Renata Rutckeviski, Francisco H. Xavier Júnior, Éverton N. Alencar, Andreza R. V. Morais, Teresa R. F. Dantas, Christian M. Oliveira, Arnóbio A. Silva Júnior, Eryvaldo S. T. Egito

Abstract:

This study aimed to obtain emulsion systems based on bullfrog oil (BO). The BO was extracted at 80ºC and analyzed by Gas Chromatography-Mass Spectrometry (GC/MS). The critical Hydrophilic-Lipophilic Balance (HLBc) Assay of the BO was performed through BO, Tween® 20, Span® 80 and deionized water mixtures using an Ultra-Turrax® and determined using dynamic light scattering, pH, electrical conductivity and creaming rate. Then, a pseudoternary phase diagram (PPD) was constructed by water titration. The GC/MS analysis of BO suggested Methyl Oleate (9.26%) as major compound. The HLBc was 12.1, wherein the correspondent emulsion showed a pH of 4.83±1.29, electrical conductivity of 103.65 µS, creaming rate of 2.51±0.54%, droplet size of 207.07±8.31 nm and polydispersity index of 0.212±0.005. The PPD showed different formulations characterized as O/W emulsions. Thus, the PPD proved to be a useful tool to produce BO emulsions, in which their constituents may vary within the range of the desired system.

Keywords: bullfrog (Rana catesbeiana Shaw) oil, emulsion production, hydrophilic-lipophilic balance, gas chromatography/mass spectrometry analysis

Procedia PDF Downloads 492