Search results for: Microwave plasma

Authors: Rijnbout-St.James Willem, Lindner Volkhard, Scholand Mary Beth, Ashton M. Tillett, Di Gennaro Michael Jude, Smith Silvia Enrica

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Introduction: Fibrosing lung diseases are characterized by changes in the lung interstitium and are classified based on etiology: 1) environmental/exposure-related, 2) autoimmune-related, 3) sarcoidosis, 4) interstitial pneumonia, and 4) idiopathic. Among interstitial lung diseases (ILD) idiopathic forms, idiopathic pulmonary fibrosis (IPF) is the most severe. Pathogenesis of IPF is characterized by an increased presence of proinflammatory mediators, resulting in alveolar injury, where injury to alveolar epithelium precipitates an increase in collagen deposition, subsequently thickening the alveolar septum and decreasing gas exchange. Identifying biomarkers implicated in the pathogenesis of lung fibrosis is key to developing new therapies and improving the efficacy of existing therapies. The transforming growth factor-beta (TGF-B1), a mediator of tissue repair associated with WNT5A signaling, is partially responsible for fibroblast proliferation in ILD and is the target of Pirfenidone, one of the antifibrotic therapies used for patients with IPF. Canonical TGF-B signaling is mediated by the proteins SMAD 2/3, which are, in turn, indirectly regulated by Collagen Triple Helix Repeat Containing 1 (CTHRC1). In this study, we tested the following hypotheses: 1) CTHRC1 is more elevated in the ILD cohort compared to unaffected controls, and 2) CTHRC1 is differently expressed among ILD types. Material and Methods: CTHRC1 levels were measured by ELISA in 171 plasma samples from the deidentified University of Utah ILD cohort. Data represent a cohort of 131 ILD-affected participants and 40 unaffected controls. CTHRC1 samples were categorized by a pulmonologist based on affectation status and disease subtypes: IPF (n = 45), sarcoidosis (4), nonspecific interstitial pneumonia (16), hypersensitivity pneumonitis (n = 7), interstitial pneumonia (n=13), autoimmune (n = 15), other ILD - a category that includes undifferentiated ILD diagnoses (n = 31), and unaffected controls (n = 40). We conducted a single-factor ANOVA of plasma CTHRC1 levels to test whether CTHRC1 variance among affected and non-affected participants is statistically significantly different. In-silico analysis was performed with Ingenuity Pathway Analysis® to characterize the role of CTHRC1 in the pathway of lung fibrosis. Results: Statistical analyses of CTHRC1 in plasma samples indicate that the average CTHRC1 level is significantly higher in ILD-affected participants than controls, with the autoimmune ILD being higher than other ILD types, thus supporting our hypotheses. In-silico analyses show that CTHRC1 indirectly activates and phosphorylates SMAD3, which in turn cross-regulates TGF-B1. CTHRC1 also may regulate the expression and transcription of TGFB-1 via WNT5A and its regulatory relationship with CTNNB1. Conclusion: In-silico pathway analyses demonstrate that CTHRC1 may be an important biomarker in ILD. Analysis of plasma samples indicates that CTHRC1 expression is positively associated with ILD affectation, with autoimmune ILD having the highest average CTHRC1 values. While characterizing CTHRC1 levels in plasma can help to differentiate among ILD types and predict response to Pirfenidone, the extent to which plasma CTHRC1 level is a function of ILD severity or chronicity is unknown.

Keywords: interstitial lung disease, CTHRC1, idiopathic pulmonary fibrosis, pathway analyses

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Authors: Meng Miao, Jeongwoo Han, Cam Nguyen

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Ultra-wideband (UWB) time-domain impulse communication and radar systems use ultra-short duration pulses in the sub-nanosecond regime, instead of continuous sinusoidal waves, to transmit information. The pulse directly generates a very wide-band instantaneous signal with various duty cycles depending on specific usages. In UWB systems, the total transmitted power is spread over an extremely wide range of frequencies; the power spectral density is extremely low. This effectively results in extremely small interference to other radio signals while maintains excellent immunity to interference from these signals. UWB devices can therefore work within frequencies already allocated for other radio services, thus helping to maximize this dwindling resource. Therefore, impulse UWB technique is attractive for realizing high-data-rate, short-range communications, ground penetrating radar (GPR), and military radar with relatively low emission power levels. UWB antennas are the key element dictating the transmitted and received pulse shape and amplitude in both time and frequency domain. They should have good impulse response with minimal distortion. To facilitate integration with transmitters and receivers employing microwave integrated circuits, UWB antennas enabling direct integration are preferred. We present the development of two UWB antennas operating from 3.1 to 10.6 GHz and 0.3-6 GHz for UWB systems that provide direct integration with microwave integrated circuits. The operation of these antennas is based on the principle of wave propagation on a non-uniform transmission line. Time-domain EM simulation is conducted to optimize the antenna structures to minimize reflections occurring at the open-end transition. Calculated and measured results of these UWB antennas are presented in both frequency and time domains. The antennas have good time-domain responses. They can transmit and receive pulses effectively with minimum distortion, little ringing, and small reflection, clearly demonstrating the signal fidelity of the antennas in reproducing the waveform of UWB signals which is critical for UWB sensors and communication systems. Good performance together with seamless microwave integrated-circuit integration makes these antennas good candidates not only for UWB applications but also for integration with printed-circuit UWB transmitters and receivers.

Keywords: antennas, ultra-wideband, UWB, UWB communication systems, UWB radar systems

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Authors: A. Abdikian

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A quantum breathing mode has been theatrically studied in quantum dusty plasma. By using linear quantum hydrodynamic model, not only the quantum dispersion relation of rotation mode but also void structure has been derived in the presence of an external magnetic field. Although the phase velocity of the magnetized quantum breathing mode is greater than that of unmagnetized quantum breathing mode, attenuation of the magnetized quantum breathing mode along radial distance seems to be slower than that of unmagnetized quantum breathing mode. Clearly, drawing the quantum breathing mode in the presence and absence of a magnetic field, we found that the magnetic field alters the distribution of dust particles and changes the radial and azimuthal velocities around the axis. Because the magnetic field rotates the dust particles and collects them, it could compensate the void structure.

Keywords: the linear quantum hydrodynamic model, the magnetized quantum breathing mode, the quantum dispersion relation of rotation mode, void structure

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Authors: Hua Tan, David Salamon

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In this study, γ-Al2O3 powders doped with various amounts of iron were sintered via SPS process. Two heating modes – auto and manual mode were applied to observe the role of electrical induction on heating. Temperature, electric current, and pulse pattern were experimented with grade iron γ-Al2O3 powders. Phase transformation of γ to α -Al2O3 serves as a direct indicator of internal temperature, independently on measured outside temperature. That pulsing in SPS is also able to induce internal heating due to its strong electromagnetic field when dopants are conductive metals (e.g., iron) is proofed during SPS. Density and microstructure were investigated to explain the mechanism of induction heating. In addition, the role of electric pulsing and strong electromagnetic field on internal heating (induction heating) were compared and discussed. Internal heating by iron doping within electrically nonconductive samples is able to decrease sintering temperature and save energy, furthermore it is one explanation for unique features of this material fabrication technology.

Keywords: spark plasma sintering, induction heating, alumina, microstructure

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Authors: Sharmin Sultana, Nicolas Nuns, Pardis Simon, Jean-Marc Giraudon, Jean-Francois Lamonior, Nathalie D. Geyter, Rino Morent

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Environmental issues, especially air pollution, have become a huge concern of environmental legislation as a consequence of growing awareness in our global world. In this regard, control of volatile organic compounds (VOCs) emission has become an important issue due to their potential toxicity, carcinogenicity, and mutagenicity. The research of innovative technologies for VOC abatement is stimulated to accommodate the new stringent standards in terms of VOC emission. One emerging strategy is the coupling of 2 existing complementary technologies, namely here non-thermal plasma (NTP) and heterogeneous catalysis, to get a more efficient process for VOC removal in air. The objective of this current work is to investigate the abatement of trichloroethylene (TCE-highly toxic chlorinated VOC) from moist air (RH=15%) as a function of time by combined use of multi-pin-to-plate negative DC corona/glow discharge with Fe-doped cryptomelanes catalyst downstream i.e. post plasma-catalysis (PPC) process. For catalyst alone case, experiments reveal that, initially, Fe doped cryptomelane (regardless the mode of Fe incorporation by co-precipitation (Fe-K-OMS-2)/ impregnation (Fe/K-OMS-2)) exhibits excellent activity to decompose TCE compared to cryptomelane (K-OMS-2) itself. A maximum obtained value of TCE abatement after 6 min is as follows: Fe-KOMS-2 (73.3%) > Fe/KOMS-2 (48.5) > KOMS-2 (22.6%). However, with prolonged operation time, whatever the catalyst under concern, the abatement of TCE decreases. After 111 min time of exposure, the catalysts can be ranked as follows: Fe/KOMS-2 (11%) < K-OMS-2 (12.3%) < Fe-KOMS-2 (14.5%). Clearly, this phenomenon indicates catalyst deactivation either by chlorination or by blocking the active sites. Remarkably, in PPC configuration (energy density = 60 J/L, catalyst temperature = 150°C), experiments reveal an enhanced performance towards TCE removal regardless the type of catalyst. After 6 min time on stream, the TCE removal efficiency amount as follows: K-OMS-2 (60%) < Fe/K-OMS-2 (79%) < Fe-K-OMS-2 (99.3%). The enhanced performances over Fe-K-OMS-2 catalyst are attributed to its high surface oxygen mobility and structural defects leading to high O₃ decomposition efficiency to give active species able to oxidize the plasma processed hazardous\by-products and the possibly remaining VOC into CO₂. Moreover, both undoped and doped catalysts remain strongly capable to abate TCE with time on stream. The TCE removal efficiencies of the PPC processes with Fe/KOMS-2 and KOMS-2 catalysts are not affected by time on stream indicating an excellent catalyst stability. When using the Fe-K-OMS-2 as catalyst, TCE abatement slightly reduces with time on stream. However, it is noteworthy to stress that still a constant abatement of 83% is observed during at least 30 minutes. These results prove that the combination of NTP with catalysts not only increases the catalytic activity but also allows to avoid, to some extent, the poisoning of catalytic sites resulting in an enhanced catalyst stability. In order to better understand the different surface processes occurring in the course of the total TCE oxidation in PPC experiments, a detailed X-ray Photoelectron Spectroscopy (XPS) and Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) study on the fresh and used catalysts is in progress.

Keywords: Fe doped cryptomelane, non-thermal plasma, plasma-catalysis, stability, trichloroethylene

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Authors: Irene Carmagnola, Valeria Chiono, Sandra Pacharra, Jochen Salber, Sean McMahon, Chris Lovell, Pooja Basnett, Barbara Lukasiewicz, Ipsita Roy, Xiang Zhang, Gianluca Ciardelli

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Thrombosis and restenosis after stenting procedure can be prevented by promoting fast stent wall endothelialisation. It is well known that surface functionalisation with antifouling molecules combining with extracellular matrix proteins is a promising strategy to design biomimetic surfaces able to promote fast endothelialization. In particular, REDV has gained much attention for the ability to enhance rapid endothelialization due to its specific affinity with endothelial cells (ECs). In this work, a two-step plasma treatment was performed to polymerize a thin layer of acrylic acid, used to subsequently graft PEGylated-REDV and polyethylene glycol (PEG) at different molar ratio with the aim to selectively promote endothelial cell adhesion avoiding platelet activation. PEGylate-REDV was provided by Biomatik and it is formed by 6 PEG monomer repetitions (Chempep Inc.), with an NH2 terminal group. PEG polymers were purchased from Chempep Inc. with two different chain lengths: m-PEG6-NH2 (295.4 Da) with 6 monomer repetitions and m-PEG12-NH2 (559.7 Da) with 12 monomer repetitions. Plasma activation was obtained by operating at 50W power, 5 min of treatment and at an Ar flow rate of 20 sccm. Pure acrylic acid (99%, AAc) vapors were diluted in Ar (flow = 20 sccm) and polymerized by a pulsed plasma discharge applying a discharge RF power of 200 W, a duty cycle of 10% (on time = 10 ms, off time = 90 ms) for 10 min. After plasma treatment, samples were dipped into an 1-(3-dimethylaminopropyl)-3- ethylcarbodiimide (EDC)/N-hydroxysuccinimide (NHS) solution (ratio 4:1, pH 5.5) for 1 h at 4°C and subsequently dipped in PEGylate-REDV and PEGylate-REDV:PEG solutions at different molar ratio (100 μg/mL in PBS) for 20 h at room temperature. Surface modification was characterized through physico-chemical analyses and in vitro cell tests. PEGylated-REDV peptide and PEG were successfully bound to the carboxylic groups that are formed on the polymer surface after plasma reaction. FTIR-ATR spectroscopy, X -ray Photoelectron Spectroscopy (XPS) and contact angle measurement gave a clear indication of the presence of the grafted molecules. The use of PEG as a spacer allowed for an increase in wettability of the surface, and the effect was more evident by increasing the amount of PEG. Endothelial cells adhered and spread well on the surfaces functionalized with the REDV sequence. In conclusion, a selective coating able to promote a new endothelial cell layer on polymeric stent surface was developed. In particular, a thin AAc film was polymerised on the polymeric surface in order to expose –COOH groups, and PEGylate-REDV and PEG were successful grafted on the polymeric substrates. The REDV peptide demonstrated to encourage cell adhesion with a consequent, expected improvement of the hemocompatibility of these polymeric surfaces in vivo. Acknowledgements— This work was funded by the European Commission 7th Framework Programme under grant agreement number 604251- ReBioStent (Reinforced Bioresorbable Biomaterials for Therapeutic Drug Eluting Stents). The authors thank all the ReBioStent partners for their support in this work.

Keywords: endothelialisation, plasma treatment, stent, surface functionalisation

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Authors: Diana Rymuszka, Konrad Terpiłowski, Lucyna Hołysz, Elena Goncharuk, Iryna Sulym

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Superhydrophobic surfaces exhibit extremely high water repellency. The commonly accepted basic criterion for such surfaces is a water contact angle larger than 150°, low contact angle hysteresis and low sliding angle. These surfaces are of special interest, because properties such as anti-sticking, anti-contamination and self-cleaning are expected. These properties are attractive for many applications such as anti-sticking of snow for antennas and windows, anti-biofouling paints for boats, waterproof clothing, self-cleaning windshields for automobiles, dust-free coatings or metal refining. The various methods for the preparation of superhydrophobic surfaces since last two decades have been reported, such as phase separation, electrochemical deposition, template method, plasma method, chemical vapor deposition, wet chemical reaction, sol-gel processing, lithography and so on. The aim of the study was to investigate the influence of modified colloidal silica, used as a filler, on the hydrophobicity of the polymer film deposited on the glass support activated with plasma. On prepared surfaces water advancing (ӨA) and receding (ӨR) contact angles were measured and then their total apparent surface free energy was determined using the contact angle hysteresis approach (CAH). The structures of deposited films were observed with the help of an optical microscope. Topographies of selected films were also determined using an optical profilometer. It was found that plasma treatment influence glass surface wetting and energetic properties that is observed in higher adhesion between polymer/filler film and glass support. Using the colloidal silica particles as a filler for the polymer thin film deposited on the glass support, it is possible to produce strongly adhering layers of superhydrophobic properties. The best superhydrophobic properties were obtained for surfaces of the film glass/polimer + modified silica covered in 89 and 100%. The advancing contact angle measured on these surfaces amounts above 150° that leads to under 2 mJ/m2 value of the apparent surface free energy. Such films may have many practical applications, among others, as dust-free coatings or anticorrosion protection.

Keywords: contact angle, plasma, superhydrophobic, surface free energy

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Authors: A. Mohammed, R. Lewis, M. Marshall

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Commonly used coatings to protect tools in die casting were used. A heat treatment and then surface coating can have a large effect on erosion damage. Samples have been tested to evaluate their resistances to erosive wear and to assess how this compares with behaviour seen for untreated material. Five commercial (PN + TiN), (PN + TiAlCN), (TiN X 2), (TiN), and (TiAlCN) coatings have been evaluated for their wear resistance. The objective was to permit an optimized selection of coatings to be used to give good resistance to erosive wear. A test-Rig has been developed to study the erosive wear in aluminium die casting and provide an environment similar to industrial operation that is more practical than using actual machines. These surfaces were analysed using a Scanning Electron Microscope (SEM) and Optical Microscopes each with a different level of resolution. Examination of coating materials revealed an important parameter associated with the failure of the coating materials.This was adhesion of the coating material to the substrate surface. A well-adhered coating withstands wear much better compared to the poorest-adhering coating.

Keywords: solid particle erosion, PVD-coatings, steel, erosion testing

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Authors: Huinan Zhang, Wenjie Jiang

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Accurate estimation of tropical cyclone intensity is of great importance for disaster prevention and mitigation. Existing techniques are largely based on satellite imagery data, and research and utilization of the inner thermal core structure characteristics of tropical cyclones still pose challenges. This paper presents a two-stage tropical cyclone intensity estimation network based on the fusion of coarse and fine-grained features from microwave brightness temperature data. The data used in this network are obtained from the thermal core structure of tropical cyclones through the Advanced Technology Microwave Sounder (ATMS) inversion. Firstly, the thermal core information in the pressure direction is comprehensively expressed through the maximal intensity projection (MIP) method, constructing coarse-grained thermal core images that represent the tropical cyclone. These images provide a coarse-grained feature range wind speed estimation result in the first stage. Then, based on this result, fine-grained features are extracted by combining thermal core information from multiple view profiles with a distributed network and fused with coarse-grained features from the first stage to obtain the final two-stage network wind speed estimation. Furthermore, to better capture the long-tail distribution characteristics of tropical cyclones, focal loss is used in the coarse-grained loss function of the first stage, and ordinal regression loss is adopted in the second stage to replace traditional single-value regression. The selection of tropical cyclones spans from 2012 to 2021, distributed in the North Atlantic (NA) regions. The training set includes 2012 to 2017, the validation set includes 2018 to 2019, and the test set includes 2020 to 2021. Based on the Saffir-Simpson Hurricane Wind Scale (SSHS), this paper categorizes tropical cyclone levels into three major categories: pre-hurricane, minor hurricane, and major hurricane, with a classification accuracy rate of 86.18% and an intensity estimation error of 4.01m/s for NA based on this accuracy. The results indicate that thermal core data can effectively represent the level and intensity of tropical cyclones, warranting further exploration of tropical cyclone attributes under this data.

Keywords: Artificial intelligence, deep learning, data mining, remote sensing

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Authors: Jana Tchekalarova, Milena Atanasova, Katerina Georgieva

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Melatonin deficit can cause a disturbance in emotional status and circadian rhythms of the endocrine system in the body. Both pharmacological and alternative approaches are applied for correction of dysfunctions driven by changes in circadian dynamics of many physiological indicators. In the present study, we tested and compare the beneficial effect of agomelatine (40 mg/kg, i.p. for 3 weeks) and endurance training on depressive behavior in two models of melatonin deficit in rat. The role of disturbed circadian rhythms of plasma melatonin and corticosterone secretion in the mechanism of these treatments was also explored. The continuous exercise program attenuated depressive responses associated with disrupted diurnal rhythm of home-cage motor activity, anhedonia in the sucrose preference test, and despair-like behavior in the forced swimming test were attenuated by agomelatine exposed to chronic constant light (CCL) and long-term exercise in pinealectomized rats. Parallel to the observed positive effect on the emotional status, agomelatine restored CCL-induced impairment of circadian patterns of plasma melatonin but not that of corticosterone. In opposite, exercise training diminished total plasma corticosterone levels and corrected its flattened pattern while it was unable to correct melatonin deficit in pinealectomy. These results suggest that the antidepressant-like effect of pharmacological and alternative approach might be mediated via two different mechanism, correction of the disturbed circadian rhythm of melatonin and corticosterone, respectively. Therefore, these treatment approaches might have a potential therapeutic application in different subpopulations of people characterized by a melatonin deficiency. This work was supported by the National Science Fund of Bulgaria (research grant # № DN 03/10; DN# 12/6).

Keywords: agomelatine, exercise training, melatonin deficit, corticosterone

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Authors: Radovan Bures, Madgalena Streckova, Maria Faberova, Pavel Kurek

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Composite material based on Fe3Si micro-particles and Mn-Zn nano-ferrite was prepared using powder metallurgy technology. The sol-gel followed by autocombustion process was used for synthesis of Mn0.8Zn0.2Fe2O4 ferrite. 3 wt.% of mechanically milled ferrite was mixed with Fe3Si powder alloy. Mixed micro-nano powder system was homogenized by the Resonant Acoustic Mixing using ResodynLabRAM Mixer. This non-invasive homogenization technique was used to preserve spherical morphology of Fe3Si powder particles. Uniaxial cold pressing in the closed die at pressure 600 MPa was applied to obtain a compact sample. Microwave sintering of green compact was realized at 800°C, 20 minutes, in air. Density of the powders and composite was measured by Hepycnometry. Impulse excitation method was used to measure elastic properties of sintered composite. Mechanical properties were evaluated by measurement of transverse rupture strength (TRS) and Vickers hardness (HV). Resistivity was measured by 4 point probe method. Ferrite phase distribution in volume of the composite was documented by metallographic analysis. It has been found that nano-ferrite particle distributed among micro- particles of Fe3Si powder alloy led to high relative density (~93%) and suitable mechanical properties (TRS >100 MPa, HV ~1GPa, E-modulus ~140 GPa) of the composite. High electric resistivity (R~6.7 ohm.cm) of prepared composite indicate their potential application as soft magnetic material at medium and high frequencies.

Keywords: micro- and nano-composite, soft magnetic materials, microwave sintering, mechanical and electric properties

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Authors: Assia Galleze, Abdurrahim Kocyigit, Nacira Cherif, Nidel Benhalilou, Nabila Attal, Chafia Touil Boukkoffa, Rachida Raache

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Introduction and aims: Chemotherapeutic agents used to inhibit cell division and reduce tumor growth, increase reactive oxygen species levels, which contributes to their genotoxicity [1]. The comet assay is an inexpensive and rapid method to detect the damage at cellular levels and has been used in various cancer populations undergoing chemotherapy [2,3]. The present study aim to assess the oxidative stress and the genotoxicity induced by chemotherapy by the determination of plasma malondialdehyde (MDA) level, protein carbonyl (PC) content, superoxide dismutase (SOD) activity and lymphocyte DNA damage in Algerian children with lymphoma. Materials and Methods: For our study, we selected thirty children with lymphoma treated in university hospital of Beni Messous, Algeria, and fifty unrelated subjects as controls, after obtaining the informed consent in accordance with the Declaration of Helsinki (1964). Plasma levels of MDA, PC and SOD activity were spectrophotometrically measured, while DNA damage was assessed by alkaline comet assay in peripheral blood leukocytes. Results and Discussion: Plasma MDA, PC levels and lymphocyte DNA damage, were found to be significantly higher in lymphoma patients than in controls (p < 0.001). Whereas, SOD activity in lymphoma patients was significantly lower than in healthy controls (p < 0.001). There were significant positive correlations between DNA damage, MDA and PC in patients (r = 0.96, p < 0.001, r = 0.97, p < 0.001, respectively), and negative correlation with SOD (r = 0.87, p < 0.01). Conclusion and Perspective: Our results indicated that, leukocytes DNA damage and oxidative stress were significantly higher in lymphoma patients, suggesting that the direct effect of chemotherapy and the alteration of the redox balance may influence oxidative/antioxidative status.

Keywords: chemotherapy, comet assay, DNA damage, lymphoma

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Authors: B. G. Muhammad, S. M. Jafar

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Neutron Activation Analysis (NAA) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) were employed to analyze the level of trace elements concentrations in sediment samples and their bioaccumulation in some aquatic species selected randomly from surface water resources in the Northern peninsula of Malaysia. The NAA results of the sediment samples indicated a wide range in concentration of different elements were observed. Fe, K, and Na were found to have major concentration values that ranges between 61,000 ± 1400 to 4,500 ± 100 ppm, 20100±1000 to 3100±600 and 3,100±600 and 200±10 ppm, respectively. Traces of heavy metals with much more contamination health concern, such as Cr and As, were also identified in many of the samples analyzed. The average specific activities of 40K, 232Th and 226Ra in soil and the corresponding radium equivalent activity and the external hazard index were all found to be lower than the maximum permissible limits (370 Bq kg-1 and 1).

Keywords: external hazard index, Neutron Activation Analysis, radium equivalent, trace elements concentrations

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Authors: Ghada A. Abdelbary, Maha M. Amin, Mostafa Abdelmoteleb

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Zaleplon (ZP) is a non-benzodiazepine poorly soluble hypnotic drug indicated for the short term treatment of insomnia having a bioavailability of about 30%. The aim of the present study is to enhance the solubility and consequently the bioavailability of ZP using hydrotropic agents (HA). Phase solubility diagrams of ZP in presence of different molar concentrations of HA (Sodium benzoate, Urea, Ascorbic acid, Resorcinol, Nicotinamide, and Piperazine) were constructed. ZP/Sodium benzoate and Resorcinol microparticles were prepared adopting melt, solvent evaporation and melt-evaporation techniques followed by XRD. Directly compressed mixed hydrotropic ZP tablets of Sodium benzoate and Resorcinol in different weight ratios were prepared and evaluated compared to the commercially available tablets (Sleep aid® 5 mg). The effect of shelf and accelerated stability storage (40°C ± 2°C/75%RH ± 5%RH) on the optimum tablet formula (F5) for six months were studied. The enhancement of ZP solubility follows the order of: Resorcinol > Sodium benzoate > Ascorbic acid > Piperazine > Urea > Nicotinamide with about 350 and 2000 fold increase using 1M of Sodium benzoate and Resorcinol respectively. ZP/HA microparticles exhibit the order of: Solvent evaporation > melt-solvent evaporation > melt > physical mixture which was further confirmed by the complete conversion of ZP into amorphous form. Mixed hydrotropic tablet formula (F5) composed of ZP/(Resorcinol: Sodium benzoate 4:1w/w) microparticles prepared by solvent evaporation exhibits in-vitro dissolution of 31.7±0.11% after five minutes (Q5min) compared to 10.0±0.10% for Sleep aid® (5 mg) respectively. F5 showed significantly higher GABA concentration of 122.5±5.5mg/mL in plasma compared to 118±1.00 and 27.8±1.5 mg/mL in case of Sleep aid® (5 mg) and control taking only saline respectively suggesting a higher neuropharmacological effect of ZP following hydrotropic solubilization.

Keywords: zaleplon, hydrotropic solubilization, plasma GABA level, mixed hydrotropy

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Authors: Ghasem Yazdanpanah, Mona Kakavand, Hassan Niknejad

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Objectives: An important issue in tissue engineering (TE) is hemocompatibility. The current engineered vessels are seriously at risk of thrombus formation and stenosis. Amnion (AM) is the innermost layer of fetal membranes that consists of epithelial and mesenchymal sides. It has the advantages of low immunogenicity, anti-inflammatory and anti-bacterial properties as well as good mechanical properties. We recently introduced the amnion as a natural biomaterial for tissue engineering. In this study, we have evaluated hemocompatibility of amnion as potential biomaterial for tissue engineering. Materials and Methods: Amnions were derived from placentas of elective caesarean deliveries which were in the gestational ages 36 to 38 weeks. Extracted amnions were washed by cold PBS to remove blood remnants. Blood samples were obtained from healthy adult volunteers who had not previously taken anti-coagulants. The blood samples were maintained in sterile tubes containing sodium citrate. Plasma or platelet rich plasma (PRP) were collected by blood sample centrifuging at 600 g for 10 min. Hemocompatibility of the AM samples (n=7) were evaluated by measuring of activated partial thromboplastin time (aPTT), prothrombin time (PT), hemolysis, and platelet aggregation tests. P-selectin was also assessed by ELISA. Both epithelial and mesenchymal sides of amnion were evaluated. Glass slide and expanded polytetrafluoroethylene (ePTFE) samples were defined as control. Results: In comparison with glass as control (13.3 ± 0.7 s), prothrombin time was increased significantly while each side of amnion was in contact with plasma (p<0.05). There was no significant difference in PT between epithelial and mesenchymal surfaces (17.4 ± 0.7 s vs. 15.8 ± 0.7 s, respectively). However, aPPT was not significantly changed after incubation of plasma with amnion epithelial and mesenchymal surfaces or glass (28.61 ± 1.39 s, 31.4 ± 2.66 s, glass, 30.76 ± 2.53 s, respectively, p>0.05). Amnion surfaces, ePTFE and glass samples have less hemolysis induction than water considerably (p<0.001), in which no differences were detected. Platelet aggregation measurements showed that platelets were less stimulated by the amnion epithelial and mesenchymal sides, in comparison with ePTFE and glass. In addition, reduction in amount of p-selectin, as platelet activation factor, after incubation of samples with PRP indicated that amnion has less stimulatory effects on platelets than ePTFE and glass. Conclusion: Amnion as a natural biomaterial has the potential to be used in tissue engineering. Our results suggest that amnion has appropriate hemocompatibility to be employed as a vascular substitute.

Keywords: amnion, hemocompatibility, tissue engineering, biomaterial

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Authors: Ekaterina S. Marchenko, Gulsharat A. Baigonakova, Kirill M. Dubovikov, Igor A. Khlusov

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NiTi alloys combine biomechanical and biochemical properties. This makes them a perfect candidate for medical applications. However, there is a serious problem with these alloys, such as the release of Ni from the matrix. Ni ions are known to be toxic to living tissues and leach from the matrix into the surrounding implant tissues due to corrosion after prolonged use. To prevent the release of Ni ions, corrosive strong coatings are usually used. Titanium nitride-based coatings are perfect corrosion inhibitors and also have good bioactive properties. However, there is an opportunity to improve the biochemical compatibility of the surface by depositing another layer. This layer can consist of elements such as calcium and phosphorus. The Ca and P ions form different calcium phosphate phases, which are present in the mineral part of human bones. We therefore believe that these elements must promote osteogenesis and osteointegration. In view of the above, the aim of this study is to investigate the effect of crystallinity on the biocompatibility of a two-layer coating deposited on NiTi substrate by sputtering. The first step of the research, apart from the NiTi polishing, is the layer-by-layer deposition of Ti-Ni-Ti by magnetron sputtering and the subsequent synthesis of this composite in an N atmosphere at 900 °C. The total thickness of the corrosion resistant layer is 150 nm. Plasma assisted RF sputtering was then used to deposit a bioactive film on the titanium nitride layer. A Ca-P powder target was used to obtain such a film. We deposited three types of Ca-P layers with different crystallinity and compared them in terms of cytotoxicity. One group of samples had no Ca-P coating and was used as a control. We obtained different crystallinity by varying the sputtering parameters such as bias voltage, plasma source current and pressure. XRD analysis showed that all coatings are calcium phosphate, but the sample obtained at maximum bias and plasma source current and minimum pressure has the most intense peaks from the coating phase. SEM and EDS showed that all three coatings have a homogeneous and dense structure without cracks and consist of calcium, phosphorus and oxygen. Cytotoxic tests carried out on three types of samples with Ca-P coatings and a control group showed that the control sample and the sample with Ca-P coating obtained at maximum bias voltage and plasma source current and minimum pressure had the lowest number of dead cells on the surface, around 11 ± 4%. Two other types of samples with Ca-P coating have 40 ± 9% and 21 ± 7% dead cells on the surface. It can therefore be concluded that these two sputtering modes have a negative effect on the corrosion resistance of the whole samples. The third sputtering mode does not affect the corrosion resistance and has the same level of cytotoxicity as the control. It can be concluded that the most suitable sputtering mode is the third with maximum bias voltage and plasma source current and minimum pressure.

Keywords: calcium phosphate coating, cytotoxicity, NiTi alloy, two-layer coating

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Authors: Oibar Martinez, Clara Oliver, Jose Miguel Miranda

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The study of dispersion phenomena in electromagnetic waves reflected by conductors at infrared and lower frequencies is a topic which finds a number of applications. We aim to explain in this work what are the most relevant ones and how this phenomenon is modeled from both optics and electromagnetics points of view. We also explain here how the amplitude of an electromagnetic wave reflected by a lossy conductor could depend on both the frequency of the incident wave, as well as on the electrical properties of the conductor, and we illustrate this phenomenon with a practical example. The mathematical analysis made by a specialist in electromagnetics or a microwave engineer is apparently very different from the one made by a specialist in optics. We show here how both approaches lead to the same physical result and what are the key concepts which enable one to understand that despite the differences in the equations the solution to the problem happens to be the same. Our study starts with an analysis made by using the complex refractive index and the reflectance parameter. We show how this reflectance has a dependence with the square root of the frequency when the reflecting material is a good conductor, and the frequency of the wave is low enough. Then we analyze the same problem with a less known approach, which is based on the reflection coefficient of the electric field, a parameter that is most commonly used in electromagnetics and microwave engineering. In summary, this paper presents a mathematical study illustrated with a worked example which unifies the modeling of dispersion effects made by specialists in optics and the one made by specialists in electromagnetics. The main finding of this work is that it is possible to reproduce the dependence of the Fresnel reflectance with frequency from the intrinsic impedance of the reflecting media.

Keywords: dispersion, electromagnetic waves, microwaves, optics

Procedia PDF Downloads 117

Authors: Maddumage Don Sandeepa Lakshad Wimalananda, Jae-Kwan Kim, Ji-Myon Lee

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Graphene is an extraordinary 2D material that shows superior electrical, optical, and mechanical properties for the applications such as transparent contacts. Further, chemical vapor deposition (CVD) technique facilitates to synthesizing of large-area graphene, including transferability. The abstract is describing the use of high surface free energy (SFE) and nano-scale high-density surface kinks (rough) existing Cu foil for CVD graphene growth, which is an opposite approach to modern use of catalytic surfaces for high-quality graphene growth, but the controllable rough morphological nature opens new era to fast synthesis (less than the 50s with a short annealing process) of graphene as a continuous film over conventional longer process (30 min growth). The experiments were shown that high SFE condition and surface kinks on Cu(100) crystal plane existing Cu catalytic surface facilitated to synthesize graphene with high monolayer and continuous nature because it can influence the adsorption of C species with high concentration and which can be facilitated by faster nucleation and growth of graphene. The fast nucleation and growth are lowering the diffusion of C atoms to Cu-graphene interface, which is resulting in no or negligible formation of bilayer patches. High energy (500W) Ar plasma treatment (inductively Coupled plasma) was facilitated to form rough and high SFE existing (54.92 mJm-2) Cu foil. This surface was used to grow the graphene by using CVD technique at 1000C for 50s. The introduced kink-like high SFE existing point on Cu(100) crystal plane facilitated to faster nucleation of graphene with a high monolayer ratio (I2D/IG is 2.42) compared to another different kind of smooth morphological and low SFE existing Cu surfaces such as Smoother surface, which is prepared by the redeposit of Cu evaporating atoms during the annealing (RRMS is 13.3nm). Even high SFE condition was favorable to synthesize graphene with monolayer and continuous nature; It fails to maintain clean (surface contains amorphous C clusters) and defect-free condition (ID/IG is 0.46) because of high SFE of Cu foil at the graphene growth stage. A post annealing process was used to heal and overcome previously mentioned problems. Different CVD atmospheres such as CH4 and H2 were used, and it was observed that there is a negligible change in graphene nature (number of layers and continuous condition) but it was observed that there is a significant difference in graphene quality because the ID/IG ratio of the graphene was reduced to 0.21 after the post-annealing with H2 gas. Addition to the change of graphene defectiveness the FE-SEM images show there was a reduction of C cluster contamination of the surface. High SFE conditions are favorable to form graphene as a monolayer and continuous film, but it fails to provide defect-free graphene. Further, plasma modified high SFE existing surface can be used to synthesize graphene within 50s, and a post annealing process can be used to reduce the defectiveness.

Keywords: chemical vapor deposition, graphene, morphology, plasma, surface free energy

Procedia PDF Downloads 234

Authors: Hai-Ying Liu, Yi-Hao Chen, Shu-Yin Pang, Feng-Hua Wang, Xiao-Fang Peng, Li-Yuan Yang, Zheng-Rong Chen, Yi Chen, Bing Zhu

Abstract:

Objective: Biliary atresia (BA) is characterized by progressive liver fibrosis. Epithelial-mesenchymal transition (EMT) has been implicated as a key mechanism in the pathogenesis of organ fibrosis. MiR-200a has been shown to repress EMT. We aim to explore the role of miR-200a in the fibrogenesis of BA. Methods: We obtained the plasma samples and liver samples from patients with BA or controls to examine the role of miR-200a. Histological liver fibrosis was assessed using the Ishak fibrosis scores. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was performed to detect the expression of miR-200a in plasma. We also evaluated the expression of miR-200a in liver tissues using tyramide signal amplification fluorescence in situ hybridization (TSA-FISH). The expression of EMT related proteins zinc finger E-box-binding homeobox 1 (ZEB1), E-cadherin and α-smooth muscle actin (α-SMA) in the liver sections were detected by immunohistochemical staining. Results: We found that the expression of miR-200a was both elevated in the plasma and liver tissues from BA patients compared with the controls. The hepatic expression of ZEB1 and α-SMA were markedly increased in the liver sections from BA patients compared to the controls, whereas E-cadherin was downregulated in the BA group. Simultaneously, we noted that the hepatic expression of miR-200a, E-cadherin and α-SMA were upregulated with the progression of liver fibrosis in the BA group, while ZEB1 was downregulated with the progression of liver fibrosis in BA patients. Conclusion: These findings suggest EMT has a critical effect on the fibrotic process of BA, and the interaction between miR-200a and ZEB1 may regulate EMT and eventually influence liver fibrogenesis of BA.

Keywords: biliary atresia, liver fibrosis, MicroRNA, epithelial-mesenchymal transition, zinc finger E-box-binding homeobox 1

Procedia PDF Downloads 347

Authors: Z. Herceg, V. Stulic, T. Vukusic, A. Rezek Jambrak

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High voltage electrical discharge plasmas are new nonthermal developing techniques used for water decontamination. To the full understanding of cell inactivation mechanisms, this study brings inactivation, recovery and cellular leakage of L. innocua cells before and after the treatment. Bacterial solution (200 mL) of L. innocua was treated in a glass reactor with a point-to-plate electrode configuration (high voltage electrode-titanium wire, was in the gas phase and grounded electrode was in the liquid phase). Argon was injected into the headspace of the reactor at the gas flow of 5 L/min. Frequency of 60, 90 and 120 Hz, time of 5 and 10 min, positive polarity and conductivity of media of 100 µS/cm were chosen to define listed parameters. With a longer treatment time inactivation was higher as well as the increase in cellular leakage. Despite total inactivation recovery of cells occurred probably because of a high leakage of proteins, compared to lower leakage of nucleic acids (DNA and RNA). In order to define mechanisms of inactivation further research is needed.

Keywords: Listeria innocua ATCC 33092, inactivation, gas phase plasma, cellular leakage, recovery of cells

Procedia PDF Downloads 166

Authors: Alena Cejkova, Martina Paldrychova, Jana Michailidu, Olga Matatkova, Jan Masak

Abstract:

Increasing the resistance of pathogenic microorganisms to many antibiotics is a serious threat to the treatment of infectious diseases and cleaning medical instruments. It should be added that the resistance of microbial populations growing in biofilms is often up to 1000 times higher compared to planktonic cells. Biofilm formation in a number of microorganisms is largely influenced by the quorum sensing regulatory mechanism. Finding external factors such as natural substances or physical processes that can interfere effectively with quorum sensing signal molecules should reduce the ability of the cell population to form biofilm and increase the effectiveness of antibiotics. The present work is devoted to the effect of chitosan as a representative of natural substances with anti-biofilm activity and non- thermal plasma (NTP) alone or in combination with polymyxin B on biofilm formation of Pseudomonas aeruginosa. Particular attention was paid to the influence of these agents on the level of quorum sensing signal molecules (acyl-homoserine lactones) during planktonic and biofilm cultivations. Opportunistic pathogenic strains of Pseudomonas aeruginosa (DBM 3081, DBM 3777, ATCC 10145, ATCC 15442) were used as model microorganisms. Cultivations of planktonic and biofilm populations in 96-well microtiter plates on horizontal shaker were used for determination of antibiotic and anti-biofilm activity of chitosan and polymyxin B. Biofilm-growing cells on titanium alloy, which is used for preparation of joint replacement, were exposed to non-thermal plasma generated by cometary corona with a metallic grid for 15 and 30 minutes. Cultivation followed in fresh LB medium with or without chitosan or polymyxin B for next 24 h. Biofilms were quantified by crystal violet assay. Metabolic activity of the cells in biofilm was measured using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) colorimetric test based on the reduction of MTT into formazan by the dehydrogenase system of living cells. Activity of N-acyl homoserine lactones (AHLs) compounds involved in the regulation of biofilm formation was determined using Agrobacterium tumefaciens strain harboring a traG::lacZ/traR reporter gene responsive to AHLs. The experiments showed that both chitosan and non-thermal plasma reduce the AHLs level and thus the biofilm formation and stability. The effectiveness of both agents was somewhat strain dependent. During the eradication of P. aeruginosa DBM 3081 biofilm on titanium alloy induced by chitosan (45 mg / l) there was an 80% decrease in AHLs. Applying chitosan or NTP on the P. aeruginosa DBM 3777 biofilm did not cause a significant decrease in AHLs, however, in combination with both (chitosan 55 mg / l and NTP 30 min), resulted in a 70% decrease in AHLs. Combined application of NTP and polymyxin B allowed reduce antibiotic concentration to achieve the same level of AHLs inhibition in P. aeruginosa ATCC 15442. The results shown that non-thermal plasma and chitosan have considerable potential for the eradication of highly resistant P. aeruginosa biofilms, for example on medical instruments or joint implants.

Keywords: anti-biofilm activity, chitosan, non-thermal plasma, opportunistic pathogens

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Authors: Ana Paula Mousinho, Ronaldo D. Mansano, Nelson Ordonez

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Carbon nanotubes are one of the main elements in nanotechnologies; their applications are in microelectronics, nano-electronics devices (photonics, spintronic), chemical sensors, structural material and currently in clean energy devices (supercapacitors and fuel cells). The use of magnetic particle decorated carbon nanotubes increases the applications in magnetic devices, magnetic memory, and magnetic oriented drug delivery. In this work, single-walled carbon nanotubes (CNTs) forest decorated with chromium were deposited at room temperature by high-density plasma chemical vapor deposition (HDPCVD) system. The CNTs forest was obtained using pure methane plasmas and chromium, as precursor material (seed) and for decorating the CNTs. Magnetron sputtering deposited the chromium on silicon wafers before the CNTs' growth. Scanning electron microscopy, atomic force microscopy, micro-Raman spectroscopy, and X-ray diffraction characterized the single-walled CNTs forest decorated with chromium. In general, the CNTs' spectra show a unique emission band, but due to the presence of the chromium, the spectra obtained in this work showed many bands that are related to the CNTs with different diameters. The CNTs obtained by the HDPCVD system are highly aligned and showed metallic features, and they can be used as photonic material, due to the unique structural and electrical properties. The results of this work proved the possibility of obtaining the controlled deposition of aligned single-walled CNTs forest films decorated with chromium by high-density plasma chemical vapor deposition system.

Keywords: CNTs forest, high density plasma deposition, high-aligned CNTs, nanomaterials

Procedia PDF Downloads 110

Authors: M. E. Kolpakova, A. A. Jakovleva, L. S. Poliakova, H. El Amghari, S. Soliman, D. R. Faizullina, V. V. Sharoyko

Abstract:

Brain neuroplasticity is associated with blood-brain barrier vascular endothelial proteoglycans and post-stroke microglial activation. The study of the mechanisms of reperfusion injury limitation by remote ischemic postconditioning (RC) is of interest due to the effects on functional recovery after cerebral ischemia. The goal of the study is the assessment of the role of syndecan-1 (SDC-1) in restriction of ischemic-reperfusion injury on middle cerebral artery model in rats using RC protocol. Randomized controlled trials were conducted. Ischemia was performed by middle cerebral artery occlusion by Belayev L. (1996) on the Wistar rat-males (n= 87) weighting 250 ± 50 g. under general anesthesia (Zoletil 100 и Xylazine 2%). Syndecan-1 (SDC-1) concentration difference in plasma samples of false operated animals and animals with brain ischemia was 30% (30 min. МСАо: 41.4 * ± 1.3 ng/ml). SDC-1 concentration in animal plasma samples with ischemia + RC protocol was 112% (30 min МСАо+ RC): 67.8**± 5.8 ng/ml). Calculation of infarction volume in the ischemia group revealed brain injury in 31.97 ± 2.5%; the volume of infarction was 13.6 ± 1.3% in 30 min. МCАо + RC group. Swelling of tissue in the group 30 min. МCАо + RC was 16 ± 2.1%; it was 47 ± 3.3%. in 30 min. МCАо group. Correlation analysis showed a high direct correlation relationship between infarct area and muscle strength in the right forelimb (КК=0.72) in the 30 min. МCАо + RC group. Correlation analysis showed very high inverse correlation between infarct area and capillary blood flow in the 30 min. МCАо + RC group (p <0.01; r = -0.98). We believe the SDC-1 molecule in blood plasma may play role of potential messenger of ischemic-reperfusion injury restriction mechanisms. This leads to infarct-limiting effect of remote ischemic postconditioning and early functioning recovery.

Keywords: ischemia, МСАо, remote ischemic postconditioning, syndecan-1

Procedia PDF Downloads 47

Authors: Xiao-Mei Zhang, Sian-Hong Tseng, Ming-Yen Lu

Abstract:

Two-dimensional (2D) transition metal dichalcogenides (TMDCs), such as MoS₂, have attracted considerable attention owing to the unique optical and electronic properties related to its 2D ultrathin atomic layer structure. MoS₂ is becoming prevalent in post-silicon digital electronics and in highly efficient optoelectronics due to its extremely low thickness and its tunable band gap (Eg = 1-2 eV). For low-power, high-performance complementary logic applications, both p- and n-type MoS₂ FETs (NFETs and PFETs) must be developed. NFETs with an electron accumulation channel can be obtained using unintentionally doped n-type MoS₂. However, the fabrication of MoS₂ FETs with complementary p-type characteristics is challenging due to the significant difficulty of injecting holes into its inversion channel. Plasma treatments with different species (including CF₄, SF₆, O₂, and CHF₃) have also been found to achieve the desired property modifications of MoS₂. In this work, we demonstrated a p-type multilayer MoS₂ enabled by selective-area doping using CHF₃ plasma treatment. Compared with single layer MoS₂, multilayer MoS₂ can carry a higher drive current due to its lower bandgap and multiple conduction channels. Moreover, it has three times the density of states at its minimum conduction band. Large-area growth of MoS₂ films on 300 nm thick SiO₂/Si substrate is carried out by thermal decomposition of ammonium tetrathiomolybdate, (NH₄)₂MoS₄, in a tube furnace. A two-step annealing process is conducted to synthesize MoS₂ films. For the first step, the temperature is set to 280 °C for 30 min in an N₂ rich environment at 1.8 Torr. This is done to transform (NH₄)₂MoS₄ into MoS₃. To further reduce MoS₃ into MoS₂, the second step of annealing is performed. For the second step, the temperature is set to 750 °C for 30 min in a reducing atmosphere consisting of 90% Ar and 10% H₂ at 1.8 Torr. The grown MoS₂ films are subjected to out-of-plane doping by CHF₃ plasma treatment using a Dry-etching system (ULVAC original NLD-570). The radiofrequency power of this dry-etching system is set to 100 W and the pressure is set to 7.5 mTorr. The final thickness of the treated samples is obtained by etching for 30 s. Back-gated MoS₂ PFETs were presented with an on/off current ratio in the order of 10³ and a field-effect mobility of 65.2 cm²V⁻¹s⁻¹. The MoS₂ PFETs photodetector exhibited ultraviolet (UV) photodetection capability with a rapid response time of 37 ms and exhibited modulation of the generated photocurrent by back-gate voltage. This work suggests the potential application of the mild plasma-doped p-type multilayer MoS₂ in UV photodetectors for environmental monitoring, human health monitoring, and biological analysis.

Keywords: photodetection, p-type doping, multilayers, MoS₂

Procedia PDF Downloads 94

Authors: S. Gowri, K. Narayanasamy, R. Krishnamurthy

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Plasma spraying, from the point of value engineering, is considered as a cost-effective technique to deposit high performance ceramic coatings on ferrous substrates for use in the aero,automobile,electronics and semiconductor industries. High-performance ceramics such as Alumina, Zirconia, and titania-based ceramics have become a key part of turbine blades,automotive cylinder liners,microelectronic and semiconductor components due to their ability to insulate and distribute heat. However, as the industries continue to advance, improved methods are needed to increase both the flexibility and speed of ceramic processing in these applications. The ceramics mentioned were individually coated on structural steel substrate with NiCr bond coat of 50-70 micron thickness with the final thickness in the range of 150 to 200 microns. Optimal spray parameters were selected based on bond strength and porosity. The 'optimal' processed specimens were super finished by lapping using diamond and green SiC abrasives. Interesting results could be observed as follows: The green SiC could improve the surface finish of lapped surfaces almost as that by diamond in case of alumina and titania based ceramics but the diamond abrasives could improve the surface finish of PSZ better than that by green SiC. The conventional random scratches could be absent in alumina and titania ceramics but in PS those marks were found to be less. However, the flatness accuracy could be improved unto 60 to 85%. The surface finish and geometrical accuracy were measured and modeled. The abrasives in the midrange of their particle size could improve the surface quality faster and better than the particles of size in low and high ranges. From the experimental investigations after lapping process, the optimal lapping time, abrasive size, lapping pressure etc could be evaluated.

Keywords: atmospheric plasma spraying, ceramics, lapping, surface qulaity, optimization

Procedia PDF Downloads 404

Authors: Zahra Ashraf

Abstract:

Flax and pumpkin seeds are a rich source of unsaturated fatty acids, antioxidants and fiber, known to have anti-atherogenic properties. Hypercholesterolemia is a state characterized by the elevated level of cholesterol in the blood. This research was designed to study the effect of flax and pumpkin seeds powder mixture on hypercholesterolemia and body weight. Rat’s species were selected as human representative. Thirty male albino rats were divided into three groups: a control group, a CD-chol group (control diet+cholesterol) fed with 1.5% cholesterol and FP-chol group (flaxseed and pumpkin seed powder+ cholesterol) fed with 1.5% cholesterol. Flax and pumpkin seed powder mixed at proportion of (5/1) (omega-3 and omega-6). Blood samples were collected to examine lipid profile and body weight was also measured. Thus the data was subjected to analysis of variance. In CD-chol group, body weight, total cholesterol TC, triacylglycerides TG in plasma, plasma LDL-C, ratio significantly increased with a decrease in plasma HDL (good cholesterol). In FP-chol group lipid parameters and body weights were decreased significantly with an increase in HDL and decrease in LDL (bad cholesterol). The mean values of body weight, total cholesterol, triglycerides, low density lipoprotein and high density lipoproteins in FP-chol group were 240.66±11.35g, 59.60±2.20mg/dl, 50.20±1.79 mg/dl, 36.20±1.62mg/dl, 36.40±2.20 mg/dl, respectively. Flaxseed and pumpkin seeds powder mixture showed reduction in body weight, serum cholesterol, low density lipoprotein and triglycerides. While significant increase was shown in high density lipoproteins when given to hypercholesterolemic rats. Our results suggested that flax and pumpkin seed mixture has hypocholesterolemic effects which were probably mediated by polyunsaturated fatty acids (omega-3 and omega-6) present in seed mixture.

Keywords: hypercolesterolemia, omega 3 and omega 6 fatty acids, cardiovascular diseases

Procedia PDF Downloads 409

Authors: Sulaiman Rabiu, Muazu Gusau Abubakar, Jafar Usman Zakari

Abstract:

The consumption of meat is of great importance as it provides a good source of proteins and significant amount of essential trace element to the body. However, contamination of meat and meat products with heavy metals is becoming a serious threat to food safety and public health. Therefore, the present study is aimed to evaluate the concentration of some heavy metals in muscles and entrails of free-ranged cattle, sheep and goats. A total of sixty (60) fresh samples of muscles, liver, kidney, small intestines and stomach of free ranged cattle, sheep and goats were collected from abattoirs of different goldmine communities of Anka, Bukkuyum, Maru andTalata-Mafara Local Government Areas of Zamfara State, Nigeria. The samples were digested using 10 mL of a mixed 70% high grade concentration of HNO₃ and 65% HCl (4:1 v/v); the mixture was heated until dense fumes disappeared forming a clear transparent solution and diluted to 50 mL with deionized water. Actual concentrations of Cd, Cr, Cu, Co, As, Ni, Mn, Pb and Zn were determined using Microwave Plasma Atomic Emission Spectrophotometer (MP-AES). From the results obtained, goat liver had the highest mean concentration of lead, arsenic, cobalt and manganese (12.43± 0.31, 14.25±0.32, 3.47± 0.86 and 12.68± 0.92 mg/kg respectively) while goat kidney had the highest concentration of copper and zinc (10.08±0.61 and 24.16±1.30 mg/kg respectively). The highest concentrations of cadmium and nickel were recorded in sheep kidney (7.75± 0.65 and 2.08±0.10 mg/kg respectively). Cattle muscles had the highest chromium concentration than all the organs analysed. The target hazard quotients (THQs) for all the metals were below 1.0, but TR which is a risk indices for carcinogenicity indicates an alarming result that requires stringent control to protect public health.Therefore, intensive public health awareness on the risk associated with contamination of heavy metals in meat should be advocated.

Keywords: contamination, goldmine, heavy metals, meat

Procedia PDF Downloads 83

Authors: Janella Salamania, Marcedon Fernandez, Matthew Villanueva Henry Ramos

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Titanium nitrite (TiN) a popular functional and decorative coating because of its golden yellow color, high hardness and superior wear resistance. It is also being studied as a diffusion barrier in integrated circuits due to its known chemical stability and low resistivity. While there have been numerous deposition methods done for TiN, most required the heating of substrates at high temperatures. In this work, TiN films are deposited on silicon (111) and (100) substrates without substrate heating using a patented magnetized sheet plasma source. Films were successfully deposited without substrate heating at various target bias, while maintaining a constant 25% N2 to Ar ratio, and deposition of time of 30 minutes. The resulting films exhibited a golden yellow color which is characteristic of TiN. X-ray diffraction patterns show the formation of TiN predominantly oriented in the (111) direction regardless of substrate used. EDX data also confirms the 1:1 stoichiometry of titanium an nitrogen. Ellipsometry measurements estimate the thickness to range from 28 nm to 33 nm. SEM images were also taken to observe the morphology of the film.

Keywords: coatings, nitrides, coatings, reactive magnetron sputtering, thin films

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Authors: Asmaa M. Fahim

Abstract:

In this elucidation, we synthesized different heterocyclic compounds attached to Benzene sulfonamide moiety via (E)-N-(4-(3-(4-bromophenyl)acryloyl)phenyl)-4-methyl benzene sulfonamide which is obtained from Nucleophilic substitution reaction between 4-methylbenzene sulfonyl chloride and 1-(4-aminophenyl)ethan-1-one in pyridine to get N-(4-acetyl phenyl)-4-methyl benzenesulfonamide which reacted 4-bromobenzal dehyde undergoes aldol condensation in NaOH to afford the corresponding chalchone 4. Moreover, the reactivity of chalchone 4 showed several active methylene derivatives utilized the pressurized microwave irradiation as a green energy resource. Chalcone 4 was allowed to react with ethyl cyanoacetate and acetylacetone, respectively, at 70 °C with pressure under microwave reaction condition to afford the 5-cyano-6-oxo-1,2,5,6-tetrahydropyridin-2-yl)-4-methylbenzenesulfonamide 6 and N-(4'-acetyl-4''-bromo-5'-oxo-2',3',4',5'-tetrahydro-[1,1':3',1''-terphenyl]-4-yl)-4-methylbenzenesulfonamide 8 derivatives. Moreover, the reactivity of this sulphonamide chalchone with NH2NH2 in EtOH and acetic acid, which gave 2,5-dihydro-1H-imidazol-4-yl)-4-methyl benzenesulfonamide, 1H-pyrazol-3-yl)-4-methyl and reactivity with NH2OH.HCl gave isoxazol-3-yl)-4-methylbenzenesulfonamide derivatives. The synthesized compounds were screened for their ADME properties and directed to antitumor activity on HepG2 hepatocellular carcinoma and MCF-7 breast cancer and exhibited excellent behavior against standard drugs; these results were confirmed through molecular simulations with different proteins. Additionally, the Density Functional Theory analysis of optimized structures investigated their physical descriptors, FMO, ESP and MEP, which correlated with biological evaluation.

Keywords: synthesis, green chemistry, antitumor activity, DFT study

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Authors: Z. Balak, M. Zakeri, M.R.Rahimipur, M. Azizieh

Abstract:

Spark Plasma Sintering is a new technique which was used for ultra high temperature ceramics such as ZrB2-based composites in recent years. Taguchi design was applied to explore effective parameters for achieving the highest hardness. Nine factors including SiC, Cf, MoSi2, HfB2 and ZrC content, milling time of Cf and SPS parameters such as temperature, time and pressure in four levels were considered through the Taguchi technique. In this study, only the effect of SPS conditions on densification and hardness were investigated. ZrB2-based composites were prepared by SPS in different temperatures (1600°C,1700°C, 1800°C, 1900°C), times (4min, 8 min, 12 min, 16min) and pressures (10MPa, 20MPa, 30MPa and 40MPa). The effect of SPS parameters on the densification and hardness were investigated. It was found, by increasing the temperature and time, from level 1 to 4, densification improved continuously. Also, the results shows hardness increases continuously by increasing temperature and time. Finally, it is concluded that temperature and time have more significant effect on densification and harness rather than pressure.

Keywords: spark plasma sintering (SPS), ultra high temperature ceramics (UHTCs), densification, hardness

Procedia PDF Downloads 398