Search results for: scanning electron microscope (SEM)

Authors: Hossain A., Chowdhury S. I.

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Introduction: The use of a gamma camera is a standard procedure in nuclear medicine facilities or hospitals to diagnose chronic kidney disease (CKD), but the gamma camera does not precisely stage the disease. The authors sought to determine whether they could use an artificial neural network to determine whether CKD was in normal or abnormal stages based on GFR values (ANN). Method: The 250 kidney patients (Training 188, Testing 62) who underwent an ultrasonography test to diagnose a renal test in our nuclear medical center were scanned using a gamma camera. Before the scanning procedure, the patients received an injection of ⁹⁹ᵐTc-DTPA. The gamma camera computes the pre- and post-syringe radioactive counts after the injection has been pushed into the patient's vein. The artificial neural network uses the softmax function with cross-entropy loss to determine whether CKD is normal or abnormal based on the GFR value in the output layer. Results: The proposed ANN model had a 99.20 % accuracy according to K-fold cross-validation. The sensitivity and specificity were 99.10 and 99.20 %, respectively. AUC was 0.994. Conclusion: The proposed model can distinguish between normal and abnormal stages of CKD by using an artificial neural network. The gamma camera could be upgraded to diagnose normal or abnormal stages of CKD with an appropriate GFR value following the clinical application of the proposed model.

Keywords: artificial neural network, glomerular filtration rate, stages of the kidney, gamma camera

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Authors: Yunusa Audu, Alona Cuevas Linatoc, Aisha Idris

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The maximum carboxylation rate of Rubisco (Vcmax) and the maximum electron transport rate (Jmax), light compensation point (LCP), light saturation point (LSP), maximum photosynthesis (Amax), and apparent quantum yield (Aqy) are gas exchange characteristics that are derived from the carbon dioxide (CO2) and light response curves. This characteristics can be affected by the level of CO2 and light received by the plant. Moreover, the characteristics determines the photosynthetic capacity of the plant. The objective of the study is to evaluate the gas exchange characteristics of selected plant species of UTHM. Photosynthetic carbon dioxide (A\Ci) and light (A/Q) response curves were measured using portable photosynthesis system (LICOR). The results shows that both A/Ci and A/Q curves increases as CO2 and light increases, but reach to a certain point where the curves will become saturated. Spathodea campanulata was having the highest Vcmax (52.14±0.005 µmolCO2 m-2s-1), Jmax (104.461±0.011 µmolCO2 m-2s-1) and Aqy (0.072±0.001 mol CO2 mol-1 photons). The highest LCP was observed in Rhaphis excelsa (69.60±0.067 µmol photons m-2s-1) while the highest LSP was recorded for Costus spicatus (1576.69±0.173 µmol photons m-2s-1). It was concluded that the plants need high light intensity and CO2 for their maximum assimilation rate.

Keywords: Gas, Co2, Exchange, Plants

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Authors: Khaled S. Al Salhen

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Aldehyde oxidase (AO) and xanthine oxidoreductase (XOR) catalyze the oxidation of many different N-heterocyclic compounds as well as aliphatic and aromatic aldehydes to their corresponding lactam and carboxylic acids respectively. The present study examines the oxidation of dimethylamino-cinnamaldehyde (DMAC), vanillin and phenanthridine by AO and xanthine by XOR from Drosophila cytosol. Therefore, the results obtained in the present study showed the DMAC, vanillin and phenanthridine substrates used were found to be good substrates of Drosophila AO and xanthine is the preferred substrate for Drosophila XOR. Km values of AO substrates were observed with DMAC (50±5.4 µM), phenanthridine (80±9.1 µM) and vanillin (303±11.7 µM) respectively for Drosophila cytosol. The Km values for DMAC and phenanthridine were ~6 and ~4 fold lower than that for vanillin as a substrate. The Km for XOR with xanthine using NAD+ as an electron acceptor was 27±4.1 µM. Relatively low Vmax values were obtained with phenanthridine (1.78±0.38 nmol/min/mg protein) and DMAC (1.80±0.35 nmol/min/mg protein). The highest Vmax was obtained from Drosophila cytosol with vanillin (7.58±2.11 nmol/min/mg protein). It is concluded these results that AO and XOR in Drosophila were able to catalyse the biotransformation of numerous substrates of the well-characterised mammalian AO and XOR. The kinetic parameters have indicated that the activity of AO of Drosophila may be a significant factor the oxidation of aromatic aldehyde compounds.

Keywords: aldehyde oxidase, xanthine oxidoreductase, dimethylamino-cinnamaldehyde, vanillin, phenanthridine, Drosophila melanogaster

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Authors: Rupa Rani, Vipin Kumar

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Endosulfan, an organochlorine pesticide is of environmental concern due to its apparent persistence and toxicity. It has been reported as contaminants in soil, air, and water and is bioaccumulated and magnified in ecosystems. The combined use of microorganisms and plants has great potential for remediating soil contaminated with organic compounds such as pesticides. The objective of this study was to evaluate whether the bacterial inoculation influences plant growth promotion, endosulfan degradation in soil and endosulfan accumulation in different plant parts. Lycopersicon esculentum L. (Tomato) was grown in endosulfan spiked soil and inoculated with endosulfan tolerant bacterial strains. Endosulfan residues from different parts of plants and soil were extracted and estimated by using gas chromatograph equipped with 63Ni electron capture detector (GC-ECD). The inoculation of bacterial strains into the soil with plants showed a beneficial effect on endosulfan degradation and plant biomass production. Maximum endosulfan (90%) degradation was observed after 120 days of bacterial inoculation in the soil. Furthermore, there was significantly less endosulfan accumulation in roots and shoots of bacterial strains inoculated plants as compared to uninoculated plants. The results show the effectiveness of inoculated endosulfan tolerant bacterial strains to increase the remediation of endosulfan contaminated soil.

Keywords: organochlorine pesticides, endosulfan, degradation, plant-bacteria partnerships

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Authors: Adam Gorine, Faten Spondon

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Python is considered the most popular programming language and offers its own ecosystem for archiving and maintaining open-source software packages. This system is called the python package index (PyPI), the repository of this programming language. Unfortunately, one-third of these software packages have vulnerabilities that allow attackers to execute code automatically when a vulnerable or malicious package is installed. This paper contributes to large-scale empirical studies investigating security issues in the python ecosystem by evaluating package vulnerabilities. These provide a series of implications that can help the security of software ecosystems by improving the process of discovering, fixing, and managing package vulnerabilities. The vulnerable dataset is generated using the NVD, the national vulnerability database, and the Snyk vulnerability dataset. In addition, we evaluated 807 vulnerability reports in the NVD and 3900 publicly known security vulnerabilities in Python Package Manager (pip) from the Snyk database from 2002 to 2022. As a result, many Python vulnerabilities appear in high severity, followed by medium severity. The most problematic areas have been improper input validation and denial of service attacks. A hybrid scanning tool that combines the three scanners bandit, snyk and dlint, which provide a clear report of the code vulnerability, is also described.

Keywords: Python vulnerabilities, bandit, Snyk, Dlint, Python package index, ecosystem, static analysis, malicious attacks

Procedia PDF Downloads 139

Authors: Carmen Sica, Elena M. Scalisi, Sara Ignoto, Ludovica Palmeri, Martina Contino, Greta Ferruggia, Antonio Salvaggio, Santi C. Pavone, Gino Sorbello, Loreto Di Donato, Roberta Pecoraro, Maria V. Brundo

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Recently, a rise in the use of wireless internet technologies such as Wi-Fi and 5G routers/modems have been demonstrated. These devices emit a considerable amount of electromagnetic radiation (EMR), which could interact with the male reproductive system either by thermal or non-thermal mechanisms. The aim of this study was to investigate the direct in vitro influence of 5G radiation on sperm quality in Mytilus galloprovincialis, considered an excellent model for reproduction studies. The experiments at 27 GHz were conducted by using a no commercial high gain pyramidal horn antenna. To evaluate the specific absorption rate (SAR), a numerical simulation has been performed. The resulting incident power density was significantly lower than the power density limit of 10 mW/cm2 set by the international guidelines as a limit for nonthermal effects above 6 GHz. However, regarding temperature measurements of the aqueous sample, it has been verified an increase of 0.2°C, compared to the control samples. This very low-temperature increase couldn’t interfere with experiments. For experiments, sperm samples taken from sexually mature males of Mytilus galloprovincialis were placed in artificial seawater, salinity 30 + 1% and pH 8.3 filtered with a 0.2 m filter. After evaluating the number and quality of spermatozoa, sperm cells were exposed to electromagnetic fields a 27GHz. The effect of exposure on sperm motility and quality was evaluated after 10, 20, 30 and 40 minutes with a light microscope and also using the Eosin test to verify the vitality of the gametes. All the samples were performed in triplicate and statistical analysis was carried out using one-way analysis of variance (ANOVA) with Turkey test for multiple comparations of means to determine differences of sperm motility. A significant decrease (30%) in sperm motility was observed after 10 minutes of exposure and after 30 minutes, all sperms were immobile and not vital. Due to little literature data about this topic, these results could be useful for further studies concerning a great diffusion of these new technologies.

Keywords: mussel, spermatozoa, sperm motility, millimeter waves

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Authors: Zaheer Ahmad, Afzal Shah

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pH responsive block copolymers consist of mPEG and glutamic acid units were syntheiszed in different formulations. The synthesized polymers were structurally investigated. Doxorubicin Hydrocholide (DOX-HCl) as a chemotherapy medication for the treatment of cancer was selected. DOX-HCl was loaded and their drug loading content and drug loading efficiency were determined. The nanocarriers were obtained in small size, well shaped and slightly negative surface charge. The release study was carried out both at pH 7.4 and 5.5 and it was revealed that the release was sustained and in controlled manner and there was no initial burst release. The in vitro release study was further carried out for different formulations with different glutamic acid moieties. Time dependent cell proliferation inhibition of the free drug and drug loaded nanoparticles against human breast cancer cell lines MCF-7 and Zr-75-30 was observed. Cellular uptakes and endocytosis were investigated by confocal laser scanning microscopy (CLSM) and flow cytometery. The biocompatibility, optimum size, shape and surface charge of the developed nanoparticles make the nanoparticles an efficient drug delivery carrier.

Keywords: doxorubicin, glutamic acid, cell proliferation inhibition, breast cancer cell

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Authors: Mesih Kocamuftuoglu, Gonca Ozan, Enver Ozan, Nalan Kaya, Sema Temizer Ozan

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Metabolic Syndrome, one of the common metabolic disorder, occurs with co-development of insulin resistance, obesity, dislipidemia and hypertension problems. Insulin resistance appears to play a pathogenic role in the metabolic syndrome. Also, there is a relationship between insulin resistance and infertility as known. Turmeric (Curcuma longa L.) a polyphenolic chemical is widely used for its coloring, flavoring, and medicinal properties, and exhibits a strong antioxidant activity. In this study, we assess the effects of turmeric on rat uterine tissue in metabolic syndrome model induced by high fructose diet. Thirty-two adult female Wistar rats weighing 220±20 g were randomly divided into four groups (n=8) as follows; control, fructose, turmeric, and fructose plus turmeric. Metabolic syndrome was induced by fructose solution 20% (w/v) in tap water, and turmeric (C.Longa) administered at the dose of 80 mg/kg body weight every other day by oral gavage. After the experimental period of 8 weeks, rats were decapitated, serum and uterine tissues were removed. Serum lipid profile, glucose, insülin levels were measured. Uterine tissues were fixed for histological analyzes. The uterine tissue sections were stained with hematoxylin-eosin (H & E) stain, then examined and photographed on a light microscope (Novel N-800Mx20). As a result, fructose consumption effected serum lipids, insulin levels, and insulin resistance significantly. Endometrium and myometrium layers were observed in normal structure in control group of uterine tissues. Perivascular edema, peri glandular fibrosis, and inflammatory cell increase were detected in fructose group. Sections of the fructose plus turmeric group showed a significant improvement in findings when compared to the fructose group. Turmeric group cell structures were observed similar with the control group. These results demonstrated that high-fructose consumption could change the structure of the uterine tissue. On the other hand, turmeric administration has beneficial effects on uterine tissue at that dose and duration when administered with fructose.

Keywords: metabolic syndrome, rat, turmeric, uterus

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Authors: H. Elmsellem, A. Aouniti, S. Radi, A. Chetouani, B. Hammouti

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The synthesis of new organic molecules offers various molecular structures containing heteroatoms and substituents for corrosion protection in acid pickling of metals. The most synthesized compounds are the nitrogen heterocyclic compounds, which are known to be excellent complex or chelate forming substances with metals. The choice of the inhibitor is based on two considerations: first it could be synthesized conveniently from relatively cheap raw materials, secondly, it contains the electron cloud on the aromatic ring or, the electro negative atoms such as nitrogen and oxygen in the relatively long chain compounds. In the present study, (NE)‐2‐methyl‐N‐(thiophen‐2‐ylmethylidene) aniline(T) was synthesized and its inhibiting action on the corrosion of mild steel in 1 M hydrochloric acid was examined by different corrosion methods, such as weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The experimental results suggest that this compound is an efficient corrosion inhibitor and the inhibition efficiency increases with the increase in inhibitor concentration. Adsorption of this compound on mild steel surface obeys Langmuir’s isotherm. Correlation between quantum chemical calculations and inhibition efficiency of the investigated compound is discussed using the Density Functional Theory method (DFT).

Keywords: mild steel, Schiff base, inhibition, corrosion, HCl, quantum chemical

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Authors: Natalie M. Wride, Xueyu Geng

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Subgrade soils of railway infrastructure are subjected to a significant number of load applications over their design life. The use of slab track on existing and future proposed rail links requires a reduced maintenance and repair regime for the embankment subgrade, due to restricted access to the subgrade soils for remediation caused by cyclic deformation. It is, therefore, important to study the deformation behaviour of soft cohesive subsoils induced as a result of long term cyclic loading. In this study, a series of oedometer tests and cyclic triaxial tests (10,000 cycles) have been undertaken to investigate the undrained deformation behaviour of soft kaolin. X-ray Computer Tomography (CT) scanning of the samples has been performed to determine the change in porosity and soil structure density from the sample microstructure as a result of the laboratory testing regime undertaken. Combined with the examination of excess pore pressures and strains obtained from the cyclic triaxial tests, the results are compared with an existing analytical solution for long term settlement considering repeated low amplitude loading. Modifications to the analytical solution are presented based on the laboratory analysis that shows good agreement with further test data.

Keywords: creep, cyclic loading, deformation, long term settlement, train loading

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Authors: Anastasia Stamatiou, Melissa Obermeyer, Ludger J. Fischer, Philipp Schuetz, Jörg Worlitschek

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This study evaluates unbranched, saturated carboxylic esters with respect to their suitability to be used as storage media for latent heat storage applications. Important thermophysical properties are gathered both by means of literature research as well as by experimental measurements. Additionally, esters are critically evaluated against other common phase-change materials in terms of their environmental impact and their economic potential. The experimental investigations are performed for eleven selected ester samples with a focus on the determination of their melting temperature and their enthalpy of fusion using differential scanning calorimetry. Transient Hot Bridge was used to determine the thermal conductivity of the liquid samples while thermogravimetric analysis was employed for the evaluation of the 5% weight loss temperature as well as of the decomposition temperature of the non-volatile samples. Both experimental results and literature data reveal the high potential of esters as phase-change materials. Their good thermal and environmental properties as well as the possibility for production from natural sources (e.g. vegetable oils) render esters as very promising for future storage applications. A particularly high short term application potential of esters could lie in low temperature storage applications where the main alternative is using salt hydrates as phase-change material.

Keywords: esters, phase-change materials, thermal properties, latent heat storage

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Authors: Mohit Kalra, Varun S., Mayuri Gandhi

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CeF3 nanophosphors has been extensively investigated in the recent years for lighting and numerous bio-applications. Down conversion emissions in CeF3:Eu3+/Tb3+ phosphors were studied with the aim of obtaining a white light emitting composition, by a simple co-precipitation method. The material was characterized by X-ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HR-TEM), Fourier Transform Infrared Spectroscopy (FT-IR) and Photoluminescence (PL). Uniformly distributed nanoparticles were obtained with an average particle size 8-10 nm. Different doping concentrations were performed and fluorescence study was carried out to optimize the dopants concentration for maximum luminescence intensity. The steady state and time resolved luminescence studies confirmed efficient energy transfer from the host to activator ions. Different concentrations of Tb 3+, Eu 3+ were doped to achieve a white light emitting phosphor for UV-based Light Emitting Diodes (LEDs). The nanoparticles showed characteristic emission of respective dopants (Eu 3+, Tb3+) when excited at the 4f→5d transition of Ce3+. The chromaticity coordinates for these samples were calculated and the CeF3 doped with Eu 3+ and Tb3+ gave an emission very close to white light. These materials may find its applications in optoelectronics and various bio applications.

Keywords: white light down-conversion, nanophosphors, LEDs, rare earth, cerium fluoride, lanthanides

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Authors: Daniela Istrati, Alina Morosan, Maria Stanca, Bogdan Purcareanu, Adrian Fudulu, Laura Olariu, Alice Buteica, Ion Mindrila, Rodica Cristescu, Dan Eduard Mihaiescu

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Our present work is related to the synthesis, characterization and applications of new nanocomposite materials based on silica mesoporous nanocompozites systems. The nanocomposite support was obtained by using a specific step–by–step multilayer structure buildup synthetic route, characterized by XRD (X-Ray Difraction), TEM (Transmission Electron Microscopy), FT-IR (Fourier Transform-Infra Red Spectrometry), BET (Brunauer–Emmett–Teller method) and loaded with Salvia officinalis plant extract obtained by a hydro-alcoholic extraction route. The sustained release of the target compounds was studied by a modified LC method, proving low release profiles, as expected for the high specific surface area support. The obtained results were further correlated with the in vitro / in vivo behavior of the nanocomposite material and recommending the silica mesoporous nanocomposites as good candidates for biomedical applications. Acknowledgements: This study has been funded by the Research Project PN-III-P2-2.1-PTE-2016-0160, 49-PTE / 2016 (PROZECHIMED) and Project Number PN-III-P4-ID-PCE-2016-0884 / 2017.

Keywords: biomedical, mesoporous, nanocomposites, natural products, sustained release

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Authors: Chidambaram Thamaraiselvan, Carlos Dosoretz

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This work will explore the influence of low voltage electric field, both alternating (AC) and direct (DC) currents, on biofouling control to highly electrically conductive self-supporting carbon nanotubes (CNT) membranes at conditions which encourage bacterial growth. A mutant strain of Pseudomonas putida S12 was used a model bacterium. The antibiofouling studies were performed with flow-through mode connecting an electric circuit in resistive mode. Major emphasis was placed on AC due to its ability of repulsing and inactivating bacteria. The observations indicate that an AC potential >1500 mV, 1 kHz frequency, 100 Ω external resistance on ground side and pulse wave above the offset (+0.45) almost completely prevented attachment of bacteria (>98.5%) and bacterial inactivation (95.3±2.5%). Findings suggest that at the conditions applied, direct electron transfer might be dominant in a decrease of cell viability. AC resulted more effective than DC, both in terms of biofouling reduction compared to cathodic DC and in terms of cell inactivation compared to anodic DC. This electrically polarized CNT membranes offer a viable antibiofouling strategy to hinder biofouling and simplify membrane care during filtration.

Keywords: bacterial attachment, biofouling control, low electric potential, water treatment

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Authors: Samvel H. Sargsyan

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Together with the study of electron-optical properties of nanostructures and proceeding from experiment-based data, the study of the mechanical properties of nanostructures has become quite actual. For the study of the mechanical properties of fullerene, carbon nanotubes, graphene and other nanostructures one of the crucial issues is the construction of their adequate mathematical models. Among all mathematical models of graphene or carbon nano-tubes, this so-called discrete-continuous model is specifically important. It substitutes the interactions between atoms by elastic beams or springs. The present paper demonstrates the construction of the discrete-continual beam model for carbon nanotubes or graphene, where the micropolar beam model based on the theory of moment elasticity is accepted. With the account of the energy balance principle, the elastic moment constants for the beam model, expressed by the physical and geometrical parameters of carbon nanotube or graphene, are determined. By switching from discrete-continual beam model to the continual, the models of micropolar elastic cylindrical shell and micropolar elastic plate are confirmed as continual models for carbon nanotube and graphene respectively.

Keywords: carbon nanotube, discrete-continual, elastic, graphene, micropolar, plate, shell

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Authors: Yomna Ibrahim El-Gazzar, Hussien Ibrahim El-Subbagh, Hanan Hanaa Georgey, Ghada S. Hassan Hassan

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Dihydrofolate reductase (DHFR) is an enzyme that has pivotal importance in biochemistry and medicinal chemistry. It catalyzes the reduction of dihydrofolate to tetrahydrofolate and intimately couples with thymidylate synthase. Thymidylate synthase is a crucial enzyme that catalyzes the reductive methylation of (dUMP) to (dTMP) utilizing N5, N10-methylenetetrahydrofolate as a cofactor. A new series of 2-substituted thio-quinazolin-4-one analogs was designed that possessed electron withdrawing or donating functional groups (Cl or OCH3) at position 6- or 7-, 4-methoxyphenyl function at position 3-.The thiol function is used to connect to either 1,2,4-triazole, or 1,3,4-thiadiazole via a methylene bridge. Most of the functional groups designed to be accommodated on the quinazoline ring such as thioether, alkyl to increase lipid solubility of polar compounds, a character very much needed in the nonclassical DHFR inhibitors. The target compounds were verified with spectral data and elemental analysis. DHFR inhibitions, as well as antitumor activity, were applied on three cell lines (MCF-7, CACO-2, HEPG-2).

Keywords: nonclassical antifolates, DHFR Inhibitors, antitumor activity, quinazoline ring

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Authors: Eko S. Kunarti, Akhmad Syoufian, Indriana Kartini, Agnes

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Fe₃O₄/SiO₂/TiO₂ nanoparticles have been synthesized and applied as a photocatalyst for the recovery of gold from the mixture of Au(III) and Cu(II) ions. The synthesis was started by the preparation of magnetite (Fe₃O₄) using coprecipitation and sonication methods, followed by SiO₂ coating on magnetite using sol-gel reactions, and then TiO₂ coating using sol-gel process. Characterization was performed by using infrared spectroscopy, X-ray diffraction, transmission electron microscopy methods. Activity of Fe₃O₄/SiO₂/TiO₂ nanoparticles was evaluated as a photocatalyst for recovery of gold through photoreduction of Au(III) ions in Au(III) and Cu(II) ions mixture with a ratio of 1:1, in a closed reactor equipped with UV lamp. The photoreduction yield was represented as a percentage (%) of reduced Au(III) which was calculated by substraction of initial Au(III) concentration by the unreduced one. The unreduced Au(III) was determined by atomic absorption spectrometry. Results showed that the Fe₃O₄/SiO₂/TiO₂ nanoparticles were successfully synthesised with excellent magnetic and photocatalytic properties. The nanoparticles present optimum activity at a pH of 5 under UV irradiation for 120 minutes. At the optimum condition, the Fe₃O₄/SiO₂/TiO₂ nanoparticles could reduce Au³⁺ to Au⁰ 97.24%. In the mixture of Au(III) and Cu(II) ions, the Au(III) ions are more easily reducible than Cu(II) ions with the reduction results of 96.9% and 45.80% for Au(III) and Cu(II) ions, respectively. In addition, the presence of Cu(II) ions has no significant effect on the amount of gold recovered and its reduction reaction rate.

Keywords: Fe₃O₄/SiO₂/TiO₂, photocatalyst, recovery, gold, Au(III) and Cu(II) mixture

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Authors: Mohammed Omar

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Using Chenopodium murale leaf, gold nanoparticles (Au NP's) were biosynthesized effectively in an amicable strategy. The casting process was used to create composite layers of sodium alginate and polyvinyl pyrrolidone. Gold nanoparticles were incorporated into the polyvinyl pyrrolidone (PVP)/ sodium alginate (NaAlg) polymer blend by casting technique. Before and after exposure to different doses of gamma irradiation (2, 4, 6 Mrad), thin films of synthesized nanocomposites were analyzed. XRD revealed the amorphous nature of polymer blends (PVP/ NaAlg), which decreased by both Au NP's embedding and consecutive doses of irradiation. FT-IR spectra revealed interactions and differences within the functional groups of their respective pristine components and dopant nano-fillers. The optical properties of PVP/NaAlg – Au NP thin films (refractive index n, energy gap Eg, Urbach energy Eu) were examined before and after the irradiation procedure. Transmission electron micrographs (TEM) demonstrated a decrease in the size of Au NP’s and narrow size distribution as the gamma irradiation dose was increased. Gamma irradiation was found to influence the electrical conductivity of synthesized composite films, as well as dielectric permittivity (ɛ′) and dielectric losses (ε″).

Keywords: PVP, SPR, γ-radiations, XRD

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Authors: Ching-Sung Lee, Wei-Chou Hsu, Han-Yin Liu, Hung-Hsi Huang, Si-Fu Chen, Yun-Jung Yang, Bo-Chun Chiang, Yu-Chuang Chen, Shen-Tin Yang

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AlGaN/GaN high electron mobility transistors (HEMTs) have been intensively studied due to their intrinsic advantages of high breakdown electric field, high electron saturation velocity, and excellent chemical stability. They are also suitable for ultra-violet (UV) photodetection due to the corresponding wavelengths of GaN bandgap. To improve the optical responsivity by decreasing the dark current due to gate leakage problems and limited Schottky barrier heights in GaN-based HEMT devices, various metal-oxide-semiconductor HEMTs (MOS-HEMTs) have been devised by using atomic layer deposition (ALD), molecular beam epitaxy (MBE), metal-organic chemical vapor deposition (MOCVD), liquid phase deposition (LPD), and RF sputtering. The gate dielectrics include MgO, HfO2, Al2O3, La2O3, and TiO2. In order to provide complementary circuit operation, enhancement-mode (E-mode) devices have been lately studied using techniques of fluorine treatment, p-type capper, piezoneutralization layer, and MOS-gate structure. This work reports an Al2O3-dielectric Al0.25Ga0.75N/GaN E-mode MOS-HEMT design by using a cost-effective ozone water oxidization technique. The present ozone oxidization method advantages of low cost processing facility, processing simplicity, compatibility to device fabrication, and room-temperature operation under atmospheric pressure. It can further reduce the gate-to-channel distance and improve the transocnductance (gm) gain for a specific oxide thickness, since the formation of the Al2O3 will consume part of the AlGaN barrier at the same time. The epitaxial structure of the studied devices was grown by using the MOCVD technique. On a Si substrate, the layer structures include a 3.9 m C-doped GaN buffer, a 300 nm GaN channel layer, and a 5 nm Al0.25Ga0.75N barrier layer. Mesa etching was performed to provide electrical isolation by using an inductively coupled-plasma reactive ion etcher (ICP-RIE). Ti/Al/Au were thermally evaporated and annealed to form the source and drain ohmic contacts. The device was immersed into the H2O2 solution pumped with ozone gas generated by using an OW-K2 ozone generator. Ni/Au were deposited as the gate electrode to complete device fabrication of MOS-HEMT. The formed Al2O3 oxide thickness 7 nm and the remained AlGaN barrier thickness is 2 nm. A reference HEMT device has also been fabricated in comparison on the same epitaxial structure. The gate dimensions are 1.2 × 100 µm 2 with a source-to-drain spacing of 5 μm for both devices. The dielectric constant (k) of Al2O3 was characterized to be 9.2 by using C-V measurement. Reduced interface state density after oxidization has been verified by the low-frequency noise spectra, Hooge coefficients, and pulse I-V measurement. Improved device characteristics at temperatures of 300 K-450 K have been achieved for the present MOS-HEMT design. Consequently, Al2O3-dielectric Al0.25Ga0.75N/GaN E-mode MOS-HEMTs by using the ozone water oxidization method are reported. In comparison with a conventional Schottky-gate HEMT, the MOS-HEMT design has demonstrated excellent enhancements of 138% (176%) in gm, max, 118% (139%) in IDS, max, 53% (62%) in BVGD, 3 (2)-order reduction in IG leakage at VGD = -60 V at 300 (450) K. This work is promising for millimeter-wave integrated circuit (MMIC) and three-terminal active UV photodetector applications.

Keywords: MOS-HEMT, enhancement mode, AlGaN/GaN, passivation, ozone water oxidation, gate leakage

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Authors: M. S. Mrudula, M. R. Gopinathan Nair

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In order to utilize the natural rubber for developing new green polymeric materials for specialty applications, we have prepared natural rubber and polyethylene oxide based polymeric networks by two shot method. The polymeric networks thus formed have been used as chelating exchanger for metal ion binding. Chelating exchangers are, in general, coordinating copolymers containing one or more electron donor atoms such as N, S, O, and P that can form coordinate bonds with metals. Hydrogels are water- swollen network of hydrophilic homopolymer or copolymers. They acquire a great interest due to the facility of the incorporation of different chelating groups into the polymeric networks. Such polymeric hydrogels are promising materials in the field of hydrometallurgical applications and water purification due to their chemical stability. The current study discusses the swelling response of the polymeric networks as a function of time, temperature, pH and [NaCl] and sorption studies. Equilibrium swelling has been observed to depend on both structural aspects of the polymers and environmental factors. Metal ion sorption shows that these polymeric networks can be used for removal, separation, and enrichment of metal ions from aqueous solutions and can play an important role for environmental remediation of municipal and industrial wastewater.

Keywords: block copolymer, adsorption, chelating exchanger, swelling study, polymer, metal complexes

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Authors: Hasan Furkan Kurt, Tugba Nur Atabey, Onat Cavit Dereli, Ahmad Salmanogli, H. Selcuk Gecim

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In the article, the main goal is to study the effect of the plasmonic properties on the photocurrent generated by a photodetector. Fundamentally, a typical photodetector is designed and simulated using the finite element methods. To utilize the plasmonic effect, gold nanoparticles with different shape, size and morphology are buried into the intrinsic region. Plasmonic effect is arisen through the interaction of the incoming light with nanoparticles by which electrical properties of the photodetector are manipulated. In fact, using plasmonic nanoparticles not only increases the absorption bandwidth of the incoming light, but also generates a high intensity near-field close to the plasmonic nanoparticles. Those properties strongly affect the generated photocurrent. The simulation results show that using plasmonic nanoparticles significantly enhances the electrical properties of the photodetectors. More importantly, one can easily manipulate the plasmonic properties of the gold nanoparticles through engineering the nanoparticles' size, shape and morphology. Another important phenomenon is plasmon-plasmon interaction inside the photodetector. It is shown that plasmon-plasmon interaction improves the electron-hole generation rate by which the rate of the current generation is severely enhanced. This is the key factor that we want to focus on, to improve the photodetector electrical properties.

Keywords: plasmonic photodetector, plasmon-plasmon interaction, Gold nanoparticle, electrical properties

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Authors: Vladimir Kulyukin, Tanwir Zaman, Sarat Kiran Andhavarapu

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Research on nutrition label use identifies four factors that impede comprehension and retention of nutrition information by consumers: label’s location on the package, presentation of information within the label, label’s surface size, and surrounding visual clutter. In this paper, a system is presented that makes nutrition label use more effective for nutrition information comprehension and retention. The system’s front end is a smartphone application. The system’s back end is a four node Linux cluster for image recognition and data storage. Image frames captured on the smartphone are sent to the back end for skewed or aligned barcode recognition. When barcodes are recognized, corresponding nutrition labels are retrieved from a cloud database and presented to the user on the smartphone’s touchscreen. Each displayed nutrition label is positioned centrally on the touchscreen with no surrounding visual clutter. Wikipedia links to important nutrition terms are embedded to improve comprehension and retention of nutrition information. Standard touch gestures (e.g., zoom in/out) available on mainstream smartphones are used to manipulate the label’s surface size. The nutrition label database currently includes 200,000 nutrition labels compiled from public web sites by a custom crawler. Stress test experiments with the node cluster are presented. Implications for proactive nutrition management and food policy are discussed.

Keywords: mobile computing, cloud computing, nutrition label use, nutrition management, barcode scanning

Procedia PDF Downloads 373

Authors: Kah Yan How, Peh Fern Ong, Keang Peng Song

Abstract:

Porphyromonas gingivalis is a black-pigmented, anaerobic Gram-negative bacterium that is important in the progression of chronic and severe periodontitis. This organism has an essential requirement for iron, which is usually obtained from hemin, using specific membrane receptors, proteases, and lipoproteins. In this study, we report the characterization of a novel 24 kDa hemin-binding protein, HmuX, in P. gingivalis W50. The hmuX gene is 651 bp long which encodes for a 217 amino acid protein. HmuX was found to be identical at the C-terminus to the previously reported HmuY protein, differing by an additional 74 amino acids at the N-terminus. Recombinant HmuX demonstrated hemin-binding ability by LDS- PAGE and TMBZ staining. Sequence analysis of HmuX revealed a putative lipoprotein attachment site, suggesting its possible role as a lipoprotein. HmuX was also localized to the outer cell surface by transmission electron microscopy. Northern analysis showed hmuX to be transcribed as a single gene and that hmuX mRNA was tightly regulated by the availability of extra-cellular hemin. P. gingivalis isogenic mutant deficient in hmuX gene exhibited significant growth retardation under hemin-limited conditions. Taken together, these results suggest that HmuX is a hemin-binding lipoprotein, important in hemin utilization for the growth of P. gingivalis.

Keywords: Porphyromonas gingivalis, periodontal diseases, HmuX, protein characterization

Procedia PDF Downloads 222

Authors: Antonio Gioiosa, Simone Doanti, Eric Flumerfelt, Luca Morescalchi, Elena Pedreschi, Gianantonio Pezzullo, Ryan A. Rivera, Franco Spinella

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The Mu2e experiment at Fermilab aims to measure the charged-lepton flavour violating neutrino-less conversion of a negative muon into an electron in the field of an aluminum nucleus. With the expected experimental sensitivity, Mu2e will improve the previous limit of four orders of magnitude. The Mu2e data acquisition (DAQ) system provides hardware and software to collect digitized data from the tracker, calorimeter, cosmic ray veto, and beam monitoring systems. Mu2e’s trigger and data acquisition system (TDAQ) uses otsdaq as its solution. developed at Fermilab, otsdaq uses the artdaq DAQ framework and art analysis framework, under-the-hood, for event transfer, filtering, and processing. Otsdaq is an online DAQ software suite with a focus on flexibility and scalability while providing a multi-user, web-based interface accessible through the Chrome or Firefox web browser. The detector read out controller (ROC) from the tracker and calorimeter stream out zero-suppressed data continuously to the data transfer controller (DTC). Data is then read over the PCIe bus to a software filter algorithm that selects events which are finally combined with the data flux that comes from a cosmic ray veto system (CRV).

Keywords: trigger, daq, mu2e, Fermilab

Procedia PDF Downloads 155

Authors: Xinyong Li

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A new coupling system was constructed by combining photo-electrochemical cell with eletro-fenton cell (PEC-EF). The electrode material in this system was derived from MnyFe₁₋yCo Prussian-Blue-Analog (PBA). Mn₀.₄Fe₀.₆Co₀.₆₇-N@C spin-coated on carbon paper behaved as the gas diffusion cathode and Mn₀.₄Fe₀.₆Co₀.₆₇O₂.₂ spin-coated on fluorine-tin oxide glass (FTO) as anode. The two separated cells could degrade Sulfamethoxazole (SMX) simultaneously and some coupling mechanisms by PEC and EF enhancing the degradation efficiency were investigated. The continuous on-site generation of H₂O₂ at cathode through an oxygen reduction reaction (ORR) was realized over rotating ring-disk electrode (RRDE). The electron transfer number (n) of the ORR with Mn₀.₄Fe₀.₆Co₀.₆₇-N@C was 2.5 in the selected potential and pH range. The photo-electrochemical properties of Mn₀.₄Fe₀.₆Co₀.₆₇O₂.₂ were systematically studied, which displayed good response towards visible light. The photo-induced electrons at anode can transfer to cathode for further use. Efficient photo-electro-catalytic performance was observed in degrading SMX. Almost 100% SMX removal was achieved in 120 min. This work not only provided a highly effective technique for antibiotic treatment but also revealed the synergic effect between PEC and EF.

Keywords: Electro-Fenton, photo-electrochemical, synergic effect, sulfamethoxazole

Procedia PDF Downloads 142

Authors: Raqiqa Tur Rasool, Ghulam Abbas Ashraf

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This study presents the synthesis and application of Carbon@NiCoFeS nanoparticles as a photocatalyst for the degradation of organic pollutants through peroxymonosulfate (PMS) activation. The Carbon@NiCoFeS nanoparticles, synthesized via a hydrothermal method, exhibit a highly crystalline and uniformly distributed nanostructure, as confirmed by XRD, SEM, TEM, and FTIR analyses. The photocatalytic performance was tested using ibuprofen (IBU) as a model pollutant under visible light, demonstrating remarkable efficiency across various conditions, including different concentrations of photocatalyst and PMS and a range of pH values. The enhanced activity is attributed to the synergistic effects of Ni, Co, and Fe, promoting effective electron-hole separation and reactive radical generation, primarily SO4•− and •OH. Quenching experiments highlighted sulfate radicals' predominant role in the degradation process. The Carbon@NiCoFeS photocatalyst also showed excellent reusability and stability over multiple cycles, and its versatility in degrading various organic pollutants underscores its potential for practical wastewater treatment applications. This research offers significant insights into multi-metal sulfide photocatalyst design, showcasing Carbon@NiCoFeS nanoparticles' promising role in environmental remediation via efficient PMS activation.

Keywords: NiCoFeS nanoparticles, photocatalytic degradation, peroxymonosulfate activation, organic pollutant removal, wastewater treatment

Procedia PDF Downloads 47

Authors: Diana Serbezeanu, Ionela-Daniela Carja, Tachita Vlad-Bubulac, Sergiu Sova

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New phosphorus-containing monomers having methoxy end functional groups were prepared from methyl 4-hydroxybenzoate and two different dichlorides with phosphorus, namely phenyl phosphonic dichloride and phenyl dichlorophosphate. The structures of the monomers were confirmed by FTIR and NMR spectroscopy. The assignments for the 1H, 13C and 31P chemical shifts are based on 1D and 2D NMR homo- and heteronuclear correlations (H,H-COSY (Correlation Spectroscopy), H,C-HMQC (Heteronuclear Multiple Quantum Correlation and H,C-HMBC (Heteronuclear Multiple Bond Correlation)) and 31P-13C couplings. The monomers exhibited good solubility in common organic solvents. Dimethyl sulfoxide was to be a good solvent to grow crystals of considerable size which were investigated by X-ray analysis. One of these two new monomers presented thermotropic liquid crystalline behaviour, as revealed by differential scanning calorimetry (DSC), polarized light microscopy (PLM) and X-ray diffraction (XRD). The transition temperature from crystal to liquid crystalline state (K→LC) was 143°C and from the LC to isotropic state (LC→I) was 167°C. Upon heating, bis(4-(methoxycarbonyl)phenyl formed fine textures, difficult to be ascribed to smectic or nematic phases. Upon cooling from the isotropic state, bis(4-(methoxycarbonyl)phenyl exhibited a mosaic-type texture. X-ray diffraction measurements at small angles (SAXS) of bis(4-(methoxycarbonyl)phenyl showed two peaks at 1.8 Å and 3.5 Å, respectively suggesting organization at supramolecular level.

Keywords: phosphorus-containing monomers, polarized light microscopy, structure investigation, thermotropic liquid crystalline properties

Procedia PDF Downloads 299

Authors: Mohamad Bolandmartabe, Nafiseh Hassani, Saeed Abdi Darake, Maryam Asghari

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Dogs are highly susceptible to diseases, nutritional problems, toxins, and parasites, with parasitic infections being common and causing hardship in their lives. Some important internal parasites include worms (such as roundworms and tapeworms) and protozoa, which can lead to anemia in dogs. Important bloodborne parasites in dogs include microfilariae and adult forms of Dirofilaria immitis, Dipetalonema reconditum, Babesia, Trypanosoma, Hepatozoon, Leishmania, Ehrlichia, and Hemobartonella. Babesia and Hemobartonella are parasites that reside inside red blood cells and cause regenerative anemia by directly destroying the red blood cells. Hepatozoon, Leishmania, and Ehrlichia are also parasites that reside within white blood cells and can infiltrate other tissues, such as the liver and lymph nodes. Since intermediate hosts are more commonly found in the open environment, the prevalence of parasites in stray and free-roaming dogs is higher compared to pet dogs. Furthermore, pet dogs are less exposed to internal and external parasites due to better care, hygiene, and being predominantly indoors. Therefore, they are less likely to be affected by them. Among the parasites, Leishmania carries significant importance as it is shared between dogs and humans, causing a dangerous disease known as visceral Leishmaniasis or kala-azar and cutaneous Leishmaniasis. Furthermore, dogs can act as reservoirs and spread the disease agent within human communities. Therefore, timely and accurate diagnosis of these diseases in dogs can be highly beneficial in preventing their occurrence in humans. In this article, we employed the Giemsa staining technique under a light microscope for the identification of bloodborne parasites in dogs. However, considering the negative impact of these parasites on the natural life of dogs, the development of chronic diseases, and the gradual loss of the animal's well-being, rapid and timely diagnosis is essential. Serological methods and PCR are available for the diagnosis of certain parasites, which have high sensitivity and desirable characteristics. Therefore, this research aims to investigate the molecular aspects of bloodborne parasites in dogs referred to veterinary hospitals in Tehran city.

Keywords: leishmaniasis, babesiosis, ehrlichiosis, dirofilariasis, hepatozoonosis

Procedia PDF Downloads 101

Authors: Chargui Ridha, Agrebi Sameh

Abstract:

The integration of phase change materials (PCM) for the storage of thermal energy during the period of sunshine before being released during the night is a complement of free energy to improve the system formed by a solar collector, tank storage, and a heat exchanger. This paper is dedicated to the design of a thermal storage tank based on a PCM-based heat exchanger. The work is divided into two parts: an experimental part using paraffin as PCM was carried out within the Laboratory of Thermal Processes of Borj Cedria in order to improve the performance of the system formed by the coupling of a flat solar collector and a thermal storage tank and to subsequently determine the influence of PCM on the whole system. This phase is based on the measurement instrumentation, namely, a differential scanning calorimeter (DSC) and the thermal analyzer (hot disk: HOT DISK) in order to determine the physical properties of the paraffin (PCM), which has been chosen. The second phase involves the detailed design of the PCM heat exchanger, which is incorporated into a thermal storage tank and coupled with a solar air collector installed at the Research and Technology Centre of Energy (CRTEn). A numerical part based on the TRANSYS and Fluent software, as well as the finite volume method, was carried out for the storage reservoir systems in order to determine the temperature distribution in each chosen system.

Keywords: phase change materials, storage tank, heat exchanger, flat plate collector

Procedia PDF Downloads 94

Authors: Jinliang Yuan, Jong-Sung Yu, Bengt Sundén

Abstract:

A computational fluid dynamics (CFD) model is developed for rechargeable non-aqueous electrolyte lithium-air batteries with a partial opening for oxygen supply to the cathode. Multi-phase transport phenomena occurred in the battery are considered, including dissolved lithium ions and oxygen gas in the liquid electrolyte, solid-phase electron transfer in the porous functional materials and liquid-phase charge transport in the electrolyte. These transport processes are coupled with the electrochemical reactions at the active surfaces, and effects of discharge reaction-generated solid Li2O2 on the transport properties and the electrochemical reaction rate are evaluated and implemented in the model. The predicted results are discussed and analyzed in terms of the spatial and transient distribution of various parameters, such as local oxygen concentration, reaction rate, variable solid Li2O2 volume fraction and porosity, as well as the effective diffusion coefficients. It is found that the effect of the solid Li2O2 product deposited at the solid active surfaces is significant on the transport phenomena and the overall battery performance.

Keywords: Computational Fluid Dynamics (CFD), modeling, multi-phase, transport phenomena, lithium-air battery

Procedia PDF Downloads 451