Search results for: thermally grown oxide

Authors: Zue Chin Chang, Shih-Chang Liang

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RF magnetron sputtering is used on the ceramic targets, each of which contains zinc oxide (ZnO), zinc oxide doped with aluminum (AZO) and zinc oxide doped with gallium (GZO). The electric conduction mechanism of the AZO and GZO films came mainly from the Al and Ga, the oxygen vacancies, Zn interstitial atoms, and Al and/or Ga interstitial atoms. AZO and GZO films achieved higher conduction than did ZnO film, it being ion vacant and nonstoichiometric. The XRD analysis showed a preferred orientation along the (002) plane for ZnO, AZO, and GZO films.

Keywords: ZnO, AZO, GZO, doped, sputtering

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Authors: Oluwatosin A. Ijabadeniyi, Faith Semwayo

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Preference for consumption of fresh and minimally processed fruits and vegetables continues to be on the upward trend however food-borne outbreaks related to them have also been on the increase. In this study the effect of zinc oxide nanoparticles on controlling Listeria monocytogenes ATCC 7644 in tomatoes and carrots during storage was investigated. Nutrient broth was inoculated with Listeria monocytogenes ATCC 7644 and thereafter inoculated with 0.3mg/ml nano-zinc oxide solution and 1.2mg/ml nano-zinc oxide solution and 200ppm chlorine was used as a control. Whole tomatoes and carrots were also inoculated with Listeria monocytogenes ATCC 7644 after which they were dipped into zinc oxide nanoparticle solutions and chlorine solutions. 1.2 mg/ml had a 2.40 log reduction; 0.3mg/ml nano-zinc oxide solution had a log reduction of 2.15 in the broth solution. There was however a 4.89 log and 4.46 reduction by 200 ppm chlorine in tomato and carrot respectively. Control with 0.3 mg/ml zinc oxide nanoparticles resulted in a log reduction of 5.19 in tomato and 3.66 in carrots. 1.2 mg/ml nanozinc oxide solution resulted in a 5.53 log reduction in tomato and a 4.44 log reduction in carrots. A combination of 50ppm Chlorine and 0.3 mg/ml nanozinc oxide was also used and resulted in log reductions of 5.76 and 4.84 respectively in tomatoes and carrots. Treatments were more effective in tomatoes than in carrots and the combination of 50ppm Chlorine and 0.3 mg/ml ZnO resulted in the highest log reductions in both vegetables. Statistical analysis however showed that there was no significant difference between treatments with Chlorine and nanoparticle solutions. This study therefore indicates that zinc oxide nanoparticles have the potential for use as a control agent in the fresh produce industry.

Keywords: Listeria monocytogenes, nanoparticles, tomato, carrot

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Authors: Nuray Ucar, Pelin Altay, Ilkay Ozsev Yuksek

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Graphene oxide fibers have recently received increasing attention due to their excellent properties such as high specific surface area, high mechanical strength, good thermal properties and high electrical conductivity. They have shown notable potential in various applications including batteries, sensors, filtration and separation and wearable electronics. Carbon nanotubes (CNTs) have unique structural, mechanical, and electrical properties and can be used together with graphene oxide fibers for several application areas such as lithium ion batteries, wearable electronics, etc. Metals salts that can be converted into metal ions and metal oxide can be also used for several application areas such as battery, purification natural gas, filtration, absorption. This study investigates the effects of CNT and metal complex compounds (MnCl₂, metal salts) on the morphological structure of graphene oxide fibers. The graphene oxide dispersion was manufactured by modified Hummers method, and continuous graphene oxide fibers were produced with wet spinning. The CNT and MnCl₂ were incorporated into the coagulation baths during wet spinning process. Produced composite continuous fibers were analyzed with SEM, SEM-EDS and AFM microscopies and as spun fiber counts were measured.

Keywords: continuous graphene oxide fiber, Hummers' method, CNT, MnCl₂

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Authors: V. P. Borker, K. S. Rane, A. J. Bhobe, R. S. Karmali

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Effluent of dye industries contains chemicals and organic dyes. Sometimes they are thrown in the water bodies without any treatment. This leads to environmental pollution and is detrimental to flora and fauna. Semiconducting oxide zinc oxide with wide bandgap 3.37 eV is used as a photocatalyst in degrading organic dyes using UV radiations. It generates electron-hole pair on exposure to UV light. If degradation is aimed at solar radiations, bandgap of zinc oxide is to be reduced so as to utilize visible radiation. Thus, in present study, zinc oxide, ZnO is synthesized from zinc oxalate, N doped zinc oxide, ZnO₁₋ₓNₓ from hydrazinated zinc oxalate, cadmium doped zinc oxide Zn₀.₉Cd₀.₁₀ and magnesium-doped zinc oxide Zn₀.₉Mg₀.₁₀ from mixed metal oxalate and hydrazinated mixed metal oxalate. The precursors were characterized by FTIR. They were decomposed to form oxides and XRD were recorded. The compounds were monophasic. Bandgap was calculated using Diffuse Reflectance Spectrum. The bandgap of ZnO was reduced to 3.24 because of precursor method of synthesis leading large surface area. The bandgap of Zn₀.₉Cd₀.₁₀ was 3.11 eV and that of Zn₀.₉Mg₀.₁₀ 3.41 eV. The lowest value was of ZnO₁₋ₓNₓ 3.09 eV. These oxides were used to degrade methylene blue, a model dye in sunlight. ZnO₁₋ₓNₓ was also used to degrade effluent of industry manufacturing colours, crayons and markers. It was observed that ZnO₁₋ₓNₓ acts as a good photocatalyst for degradation of methylene blue. It can degrade the solution within 120 minutes. Similarly, diluted effluent was decolourised using this oxide. Some colours were degraded using ZnO. Thus, the use of these two oxides could mineralize effluent. Lesser bandgap leads to more electro hole pair thus helps in the formation of hydroxyl ion radicals. These radicals attack the dye molecule, fragmentation takes place and it is mineralised.

Keywords: cadmium doped zinc oxide, dye degradation, dye effluent degradation, N doped zinc oxide, zinc oxide

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Authors: Sakti Mandal

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Varying distribution of land surface temperature in an urbanized environment is a globally addressed phenomenon. Usually has been noticed that criticality of surface temperature increases from the periphery to the urban centre. As the centre experiences maximum severity of heat throughout the year, it also represents most critical zone in terms of thermal condition. In this present study, an attempt has been taken to propose a quantitative approach of thermal critical zonation (TCZ) on the basis of seasonal temperature variation. Here the zonation is done by calculating thermal critical value (TCV). From the Landsat 8 thermal digital data of summer and winter seasons for the year 2014, the land surface temperature maps and thermally critical zonation has been prepared, and corresponding dataset has been computed to conduct the overall study of that particular study area. It is shown that TCZ can be clearly identified and analyzed by the help of inter-seasonal temperature range. The results of this study can be utilized effectively in future urban development and planning projects as well as a framework for implementing rules and regulations by the authorities for a sustainable urban development through an environmentally affable approach.

Keywords: thermal critical values (TCV), thermally critical zonation (TCZ), land surface temperature (LST), Landsat 8, Kolkata Municipal Corporation (KMC)

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Authors: Yong-Jie Lin, Yi-Feng Lin

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In this study, scandium-doped yttria-stabilized zirconia (ScYSZ) and In2O3 nanoparticles (NPs) with cubic crystalline structures were successfully prepared using a facile hydrothermal process. ScYSZ films were prepared by the pressing of ScYSZ NPs and were further used for the electrolyte of solid oxide fuel cells (SOFCs). To increase the ionic conductivity of the ScYSZ electrolyte, different amounts of In2O3 NPs [0 wt% (X(In2O3)=0), 0.21 wt% (X(In2O3)=0.001) and 1.13 wt% (X(In2O3)=0.005)] were doped in the ScYSZ films to increase their oxygen vacancy. The result shows In2O3 NP/ScYSZ films with 1.13 wt% (X(In2O3 )=0.005) In2O3 NPs doping are with largest ionic conductivity of 0.057Ω-1 cm-1 at 900oC, which is 1.6 and 1.8 times higher than YSZ and In2O3 NP/ScYSZ films with 0.21 wt% (X(In2O3)=0.001) In2O3 NPs doping, respectively.

Keywords: indium oxide/scandium doping Yttria-stabilized zirconia, solid oxide fuel cells, scandium-doped yttria-stabilized zirconia, indium oxide

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Authors: Amirhossein Hasani, Shamin Houshmand Sharifi

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In this work, we investigate humidity sensing behavior of the graphene oxide with porous silicon substrate. By evaporation method, aluminum interdigital electrodes have been deposited onto porous silicon substrate. Then, by drop-casting method graphene oxide solution was deposited onto electrodes. The porous silicon was formed by electrochemical etching. The experimental results showed that using porous silicon substrate, we obtained two times larger sensitivity and response time compared with the results obtained with silicon substrate without porosity.

Keywords: graphene oxide, porous silicon, humidity sensor, electrochemical

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Authors: Mehrji Khosravan, Mostafa Fathali-Sianib, Davood Soudbar, Sasan Talebnezhad, Mohammad-Reza Ebrahimi

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The late transition metal catalyst of the end group of transition metals in the periodic table as Ni, Fe, Co, and Pd was grown up rapidly in polyolefin industries recently. These metals with suitable ligands exhibited special characteristic properties and appropriate activities in the production of polyolefins. The ligand 1,4-bis (2,6-diisopropyl phenyl) acenaphthene was synthesized by reaction of 2,6-diisopropyl aniline and acenaphthenequinone. The ligand was added to nickel (II) dibromide salt for synthesis the 1,4-bis (2,6 diisopropylphenyl) acenaphthene nickel (II) dibromide catalyst. The structure of the ligand characterized by IR technique. The catalyst then deposited on graphene and graphene oxide by vander walss-attachment for use in Ethylene slurry polymerization process in the presence of catalyst activator such as methylaluminoxane (MAO) in hexane solvent. The structure of the catalyst characterized by IR and TEM techniques and some of the polymers were characterized by DSC. The highest activity was achieved at 600 C for catalyst.

Keywords: α-diimine nickel (II) complex, graphene as supported catalyst, late transition metal, ethylene polymerization

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Authors: L. N. Shubha, P. Madhusudana Rao

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The Polyaniline / Copper Oxide(PANI / CuO) nanocomposite was prepared by solution mixing of prepared Polyaniline and copper Oxide in Dimethyl sulfoxide (DMSO). The synthesis involved the formation of dark green colored Polyaniline-Copper Oxide nanocomposite. The synthesized polymer nano composites were characterized by XRD, FTIR, SEM and UV-Visible Spectroscopy. The characteristic peaks in XRD, FTIR and UV-Visible spectra confirmed the presence of CuO in the polymer structure. SEM analysis revealed formation of PANI/CuO nano composite The D.C. conductivity measurements were performed using two probe method for various temperatures.

Keywords: polyaniline/copper oxide (PANI/CuO) nanocomposite, XRD, SEM, FTIRand DC- conductivity, UV-visible spectra

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Authors: Jixiao Tao, Xiaoqiao He

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The present study deals with the finite element (FE) analysis of thermally-induced bistable plate using various plate elements. The quadrilateral plate elements include the 4-node conforming plate element based on the classical laminate plate theory (CLPT), the 4-node and 9-node Mindlin plate element based on the first-order shear deformation laminated plate theory (FSDT), and a displacement-based 4-node quadrilateral element (RDKQ-NL20). Using the von-Karman’s large deflection theory and the total Lagrangian (TL) approach, the nonlinear FE governing equations for plate under thermal load are derived. Convergence analysis for four elements is first conducted. These elements are then used to predict the stable shapes of thermally-induced bistable plate. Numerical test shows that the plate element based on FSDT, namely the 4-node and 9-node Mindlin, and the RDKQ-NL20 plate element can predict two stable cylindrical shapes while the 4-node conforming plate predicts a saddles shape. Comparing the simulation results with ABAQUS, the RDKQ-NL20 element shows the best accuracy among all the elements.

Keywords: Bistable, finite element method, geometrical nonlinearity, quadrilateral plate elements

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Authors: Humaira Khan, Mohsin Javed, Sammia Shahid

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The reinforced photocatalytic activity of graphene oxide (GO) along with composites of ZnO nanoparticles and copper-doped ZnO nanoparticles were studied by synthesizing ZnO and copper- doped ZnO nanoparticles by co-precipitation method. Zinc acetate and copper acetate were used as precursors, whereas graphene oxide was prepared from pre-oxidized graphite in the presence of H2O2.The supernatant was collected carefully and showed high-quality single-layer characterized by FTIR (Fourier Transform Infrared Spectroscopy), TEM (Transmission Electron Microscopy), SEM (Scanning Electron Microscopy), XRD (X-ray Diffraction Analysis), EDS (Energy Dispersive Spectrometry). The degradation of methylene blue as standard pollutant under UV-Visible irradiation gave results for photocatalytic activity of dopants. It could be concluded that shrinking of optical band caused by composites of Cu-dopped nanoparticles with GO enhances the photocatalytic activity.

Keywords: degradation, graphene oxide, photocatalysis, ZnO nanoparticles and copper-doped ZnO nanoparticles

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Authors: E. Karacabey, Ş. G. Özçelik, M. S. Turan, C. Baltacıoğlu, E. Küçüköner

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Changes in textural properties of zucchini slices under effects of frying conditions were investigated. Frying time and temperature were interested process variables like slice thickness. Slice thickness was studied at three levels (2, 3, and 4 mm). Frying process was performed at two temperature levels (160 and 180 °C) and each for five different process time periods (1, 2, 3, 5, 8 and 10 min). As frying oil sunflower oil was used. Before frying zucchini slices were thermally processes in boiling water for 90 seconds to inactivate at least 80% of plant’s enzymes. After thermal process, zucchini slices were fried in an industrial fryer at specified temperature and time pairs. Fried slices were subjected to textural profile analysis (TPA) to determine textural properties. In this extent hardness, elasticity, cohesion, chewiness, firmness values of slices were figured out. Statistical analysis indicated significant variations in the studied textural properties with process conditions (p < 0.05). Hardness and firmness were determined for fresh and thermally processes zucchini slices to compare each others. Differences in hardness and firmness of fresh, thermally processed and fried slices were found to be significant (p < 0.05). This project (113R015) has been supported by TUBITAK.

Keywords: sunflower oil, hardness, firmness, slice thickness, frying temperature, frying time

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Authors: Abbas Ali Taghipoor Bafghi, Hosein Bakhoda, Fateme Khodaei Chegeni

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An experimental investigation is carried out to establish the performance characteristics of a compression ignition engine while using cerium oxide nano particles as additive in neat diesel and diesel-bio diesel blends. In the first phase of the experiments, stability of neat diesel and diesel-bio diesel fuel blends with the addition of cerium oxide nano particles are analyzed. After series of experiments, it is found that the blends subjected to high speed blending followed by ultrasonic bath stabilization improves the stability.In the second phase, performance characteristics are studied using the stable fuel blends in a single cylinder four stroke engine coupled with an electrical dynamo meter and a data acquisition system. The cerium oxide acts as an oxygen donating catalyst and provides oxygen for combustion. The activation energy of cerium oxide acts to burn off carbon deposits within the engine cylinder at the wall temperature and prevents the deposition of non-polar compounds on the cylinder wall results reduction in HC emissions. The tests revealed that cerium oxide nano particles can be used as additive in diesel and diesel-bio diesel blends to improve complete combustion of the fuel significantly.

Keywords: engine, cerium oxide, biodiesel, deposit

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Authors: D. Aboutaleb, B. Safi

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The borate glasses are known by their structural characterized by existence of unit’s structural composed by triangles and tetrahedrons boron in different configurations depending on the percentage of B2O3 in the glass chemical composition. In this paper, effect of lithium oxide addition on the thermal and physical properties of an alumina borate glass, was investigated. It was found that the boron abnormality has a significant effect in the change of glass properties according to the addition rate of lithium oxide.

Keywords: borate glasses, triangles and tetrahedrons boron, lithium oxide, boron anomaly, thermal properties, physical properties

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Authors: Ismail Seckin Cardakli, Mustafa Engin Kocadagistan, Ersin Arslan

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In this study, mechanochemical behaviour of aluminium - boron oxide - melamine ternary system was investigated by high energy ball milling. According to the reaction Al + B₂O₃ = Al₂O₃ + B, stochiometric amount of aluminium and boron oxide with melamine up to ten percent of total weight was used in the experiments. The powder characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) after leaching of product by 1M HCl acid. Results show that mechanically induced self-sustaining reaction (MSR) between aluminium and boron oxide takes place after four hours high energy ball milling. Al₂O₃/h-BN composite powder is obtained as the product of aluminium - boron oxide - melamine ternary system.

Keywords: high energy ball milling, hexagonal boron nitride, mechanically induced self-sustaining reaction, melamine

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Authors: Shalini Rajput, Dinesh Mohan

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Water is the most important and essential resources for existing of life on the earth. Water quality is gradually decreasing due to increasing urbanization and industrialization and various other developmental activities. It can pose a threat to the environment and public health therefore it is necessary to remove hazardous contaminants from wastewater prior to its discharge to the environment. Recently, magnetic iron oxide nanoparticles have been arise as significant materials due to its distinct properties. This article focuses on the synthesis method with a possible mechanism, structure and application of magnetic iron oxide nanoparticles. The various characterization techniques including X-ray diffraction, transmission electron microscopy, scanning electron microscopy with energy dispersive X-ray, Fourier transform infrared spectroscopy and vibrating sample magnetometer are useful to describe the physico-chemical properties of nanoparticles. Nanosized iron oxide particles utilized for remediation of contaminants from aqueous medium through adsorption process. Due to magnetic properties, nanoparticles can be easily separate from aqueous media. Considering the importance and emerging trend of nanotechnology, iron oxide nanoparticles as nano-adsorbent can be of great importance in the field of wastewater treatment.

Keywords: nanoparticles, adsorption, iron oxide, nanotechnology

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Authors: Gyung Soo Jeon, Hong Bae Kim, Chi Jung Oh

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In order to prepare the α-alumina with low content of sodium oxide from aluminum trihydroxide as a reactant, three kinds of methods were employed as follows; the mixture of Chamotte (aggregate composed of silica and alumina), ammonium chloride and aluminum fluoride with aluminum trihydroxide under 1600°C, respectively. The sodium oxide in α-alumina produced above methods was analyzed by XRF and the particle size distribution was determined by particle size analyzer, and the specific surface area of α-alumina was measured by BET method, and phase of α-alumina produced was confirmed by XRD. Acknowledgement: This research was supported by Development Program of Technical Innovation funded by Korea Technology and Information Promotion Agency for SMEs (KTIP-2016-S2401821).

Keywords: α-alumina, sodium oxide, aluminum trihydroxide, Chamotte, ammonium chloride, aluminum fluoride

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Authors: Dalia Jomehpour, Sara Sheikhlary, Esmaeil Heydari, Mohammad Hossien Majles Ara

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In this study, we report fulvic acid-coated iron oxide nanoparticles of 10.7 ± 2.7 nm size, which serve to inhibit amyloid fibrillation formation. Although the effect of fulvic acid on tau fibrils was investigated, to our best knowledge, its inhibitory impacts on amyloid aggregation formation have been assessed neither in-vitro nor in-vivo. On the other hand, iron oxide nanoparticles exhibit anti-amyloid activity on their own. This study investigates the inhibitory effect of fulvic acid coated iron oxide nanoparticles on amyloid aggregations formed from the commonly used in-vitro model, lysozyme from chicken egg white. FESEM, XRD, and FTIR characterization confirmed that fulvic acid was coated onto the surface of the nanoparticles. The inhibitory effects of the fulvic acid coated iron oxide nanoparticles were verified by Thioflavin T assay, circular dichroism (CD), and FESEM analysis. Furthermore, the toxicity of the nanoparticles on the neuroblastoma SH-SY5Y human cell line was assessed through an MTT assay. Our results indicate that fulvic acid coated iron oxide nanoparticles can efficiently inhibit the formation of amyloid aggregations while exhibiting negligible in-vitro toxicity; thus, they can be used as anti-amyloid agents in the development of the potential drug for neurodegenerative diseases.

Keywords: Alzheimer’s disease, fulvic acid coated iron oxide nanoparticles, fulvic acid, amyloid inhibitor, polyphenols

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Authors: Durata Haciu, Ozgur Birer

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Zinc acetate solution is sonicated at high power in water and in ethanol in the absence and presence of various peroxides. In the absence of peroxides, the products are zinc oxide and layered hydroxy zinc acetate in water and in ethanol, respectively. Layered basic zinc acetate are prepared for the first time using sonochemical methods. The addition of peroxides alters the reaction mechanisms. In water, insoluble peroxides produce zinc oxides while the water soluble peroxide, i.e.hydrogen peroxide, completely destroyed the structure and casted a doubt on the accepted peroxide initiated mechanism of reactions. In ethanol,peroxide addition caused the reaction mechanism to change and some oxide formation is observed. The reaction mechanism is sensitive to water/ethanol amounts as well as the peroxide to zinc ion mole ratio.Thin zinc oxide wafers (ca. 30 nm) with band gaps of 3.24 eV were obtained.

Keywords: ultrasound, zinc oxide, hydroxy zinc acetate, fenton, peroxide initiation

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Authors: Jihyun Park, Tae Il Lee, Jae-Min Myoung

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A Silver (Ag) thin film is introduced as a template and doping source for vertically aligned p–type ZnO nanorods. ZnO nanorods were grown using a ammonium hydroxide based hydrothermal process. During the hydrothermal process, the Ag thin film was dissolved to generate Ag ions in the solution. The Ag ions can contribute to doping in the wurzite structure of ZnO and the (111) grain of Ag thin film can be the epitaxial temporal template for the (0001) plane of ZnO. Hence, Ag–doped p–type ZnO nanorods were successfully grown on the substrate, which can be an electrode or semiconductor for the device application. To demonstrate the potentials of this idea, p–n diode was fabricated and its electrical characteristics were demonstrated.

Keywords: hydrothermal process, Ag–doped ZnO nanorods, p–type ZnO

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Authors: G. C. Santini, C. Potrich, L. Lunelli, L. Vanzetti, S. Marasso, M. Cocuzza, C. Pederzolli

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The relevance of circulating miRNAs as non-invasive biomarkers for several pathologies is nowadays undoubtedly clear, as they have been found to have both diagnostic and prognostic value able to add fundamental information to patients’ clinical picture. The availability of these data, however, relies on a time-consuming process spanning from the sample collection and processing to the data analysis. In light of this, strategies which are able to ease this procedure are in high demand and considerable effort have been made in developing Lab-on-a-chip (LOC) devices able to speed up and standardise the bench work. In this context, a very promising polydimethylsiloxane (PDMS)-based microdevice which integrates the processing of the biological sample, i.e. purification of extracellular miRNAs, and reverse transcription was previously developed in our lab. In this study, we aimed at the improvement of the miRNA extraction performances of this micro device by increasing the ability of its surface to absorb extracellular miRNAs from biological samples. For this purpose, we focused on the modulation of two properties of the material: roughness and charge. PDMS surface roughness was modulated by casting with several templates (terminated with silicon oxide coated by a thin anti-adhesion aluminum layer), followed by a panel of curing conditions. Atomic force microscopy (AFM) was employed to estimate changes at the nanometric scale. To introduce modifications in surface charge we functionalized PDMS with different mixes of positively charged 3-aminopropyltrimethoxysilanes (APTMS) and neutral poly(ethylene glycol) silane (PEG). The surface chemical composition was characterized by X-ray photoelectron spectroscopy (XPS) and the number of exposed primary amines was quantified with the reagent sulfosuccinimidyl-4-o-(4,4-dimethoxytrityl) butyrate (s-SDTB). As our final end point, the adsorption rate of all these different conditions was assessed by fluorescence microscopy by incubating a synthetic fluorescently-labeled miRNA. Our preliminary analysis identified casting on thermally grown silicon oxide, followed by a curing step at 85°C for 1 hour, as the most efficient technique to obtain a PDMS surface roughness in the nanometric scaleable to trap miRNA. In addition, functionalisation with 0.1% APTMS and 0.9% PEG was found to be a necessary step to significantly increase the amount of microRNA adsorbed on the surface, therefore, available for further steps as on-chip reverse transcription. These findings show a substantial improvement in the extraction efficiency of our PDMS microdevice, ultimately leading to an important step forward in the development of an innovative, easy-to-use and integrated system for the direct purification of less abundant circulating microRNAs.

Keywords: circulating miRNAs, diagnostics, Lab-on-a-chip, polydimethylsiloxane (PDMS)

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Authors: Miksusanti, Herlina, Wiwin

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The research about modification uwi starch (Dioscorea alata L) by using propylene oxide has been done. Concentration of propylene oxide were 6%(v/w), 8%(v/w), and 10%(v/w). The amilograf parameters after modification were characteristic breakdown viscosity 43 BU and setback viscosity 975 BU. The modification starch have edible properties according to FDA (Food and Drug Administration) which have degree of modification < 7%, degree of substitution < 0,1 and propylene oxide concentration < 10%(v/w). The best propylene oxide in making of edible film was 8 %( v/w). The starch control can be made into edible film with thickness 0,136 mm, tensile strength 20,4605 MPa and elongation 22%. Modification starch of uwi can be made into edible film with thickness 0,146 mm, tensile strength 25, 3521 Mpa, elongation 30% and water vapor transmission 7, 2651 g/m2/24 hours. FTIR characterization of uwi starch showed the occurrence of hydroxypropylation. The peak spectrum at 2900 cm-1 showed bonding of C-H from methyl group, which is characteristic for modification starch with hydroxypropyl. Characterization with scanning electron microscopy showed that modification of uwi starch has turned the granule of starch to be fully swallon.

Keywords: uwi starch, edible film, propylen oxide, modification

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Authors: Poonam Yadav, Dong Bok Lee

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Isothermal oxidation at 800°C for 50h and Cyclic oxidation at 600°C and 800°C for 40h of Pure Ti and Ti64 were performed in a muffle furnace. In Cyclic oxidation, massive scale spallation occurred, and the oxide scale cracks and peels off were observed at high temperature, it represents oxide scale that formed during cyclic oxidation was spalled out owing to stresses due to thermal shock generated during repetitive oxidation and subsequent cooling. The thickness of scale is larger in cyclic oxidation than the isothermal case. This is due to inward diffusion of oxygen through oxide scales and/or pores and cracks in cyclic oxidation.

Keywords: cyclic, diffusion, isothermal, cyclic

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Authors: Ghada Ben Hamad, Zohir Younsi, Fabien Salaun, Hassane Naji, Noureddine Lebaz

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The graphene oxide (GO) material has attracted much attention for solar energy applications. This paper reports the synthesis and characterization of partially oxidized graphite oxide (GTO). GTO was obtained by modified Hummers method, which is based on the chemical oxidation of natural graphite. Several samples were prepared with different oxidation degree by an adjustment of the oxidizing agent’s amount. The effect of the oxidation degree on the chemical structure and on the morphology of GTO was determined by using Fourier transform infrared (FT-IR) spectroscopy, Energy Dispersive X-ray Spectroscopy (EDS), and scanning electronic microscope (SEM). The thermal stability of GTO was evaluated by using thermogravimetric analyzer (TGA) in Nitrogen atmosphere. The results indicate high degree oxidation of graphite oxide for each sample, proving that the process is efficient. The GTO synthesized by modified Hummers method shows promising characteristics. Graphene oxide (GO) obtained by exfoliation of GTO are recognized as a good candidate for thermal energy storage, and it will be used as solid shell material in the encapsulation of phase change materials (PCM).

Keywords: modified hummers method, graphite oxide, oxidation degree, solar energy storage

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Authors: Ali Gharib, Leila Vojdanifard, Nader Noroozi Pesyan, Mina Roshani

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We describe an efficient method for oxidation of alcohols to related aldehydes and ketones by hydrogen peroxide as oxidizing agent, under reflux conditions. Nano-graphene oxide (NGO) as a heterogeneous catalyst was used and had their activity compared with other various catalysts. This catalyst was found to be an excellent catalyst for oxidation of alcohols. The effects of various parameters, including catalyst type, nature of the substituent in the alcohols and temperature, on the yield of the carboxylic acids were studied. Nano-graphene oxide was synthesized by the oxidation of graphite powders. This nanocatalyst was found to be highly efficient in this reaction and products were obtained in good to excellent yields. The recovered nano-catalyst was successfully reused for several runs without significant loss in its catalytic activity.

Keywords: nano-graphene oxide, oxidation, aldehyde, ketone, catalyst

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Authors: Ki-Ho Nam, Haksoo Han

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Tetrapod zinc oxide whiskers (TZnO-Ws) were successfully synthesized by a thermal oxidation method. A series of transparent polyimide (PI)/TZnO-W composites were successfully synthesized via a solution-blending method. The structural and morphological features of TZnO-Ws and PI/TZnO-W composites were characterized by Fourier transform infrared spectroscopy (FT-IR), wide-angle X-Ray diffraction (WAXD), and field emission scanning electron microscope (FE-SEM). Dynamic stress behaviors were investigated in-situ during thermal imidization of the soft-baked PI/TZnO-W composite precursor and thermally cured composite films using a thin film stress analyzer (TFSA) by wafer bending technique. The PI/TZnO-W composite films exhibited an optical transparency greater than 80% at 550 nm (≤ 0.5 wt% TZnO-W content), a low coefficient of thermal expansion (CTE), and enhanced glass transition temperature. However, the thermal decomposition temperature decreased as the TZnO-W content increased. The water diffusion coefficient and water uptake of the PI/TZNO-W composite films were obtained by best fits to a Fickian diffusion model. The water resistance capacity of PI was greatly enhanced and moisture diffusion in the pure PI was retarded by incorporating the TZnO-W. The PI composite films based on TZNO-W resultantly may have potential applications in optoelectronic manufacturing processes as a flexible transparent substrate.

Keywords: polyimide (PI), tetrapod ZnO whisker (TZnO-W), transparent, dynamic stress behavior, water resistance

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Authors: Peihao Huang, Chun Zhao

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Thin-film transistors(TFTs) have the advantages of low power consumption, short reaction time, and have high research value in the field of semiconductors, based on this reason, people have focused on gallium oxide-indium oxide thin-film transistors, a relatively common thin-film transistor, elaborated and analyzed his production process, "aqueous solution method", explained the purpose of each step of operation, and finally explored the influence of potassium ions doped in the channel layer on the electrical properties of the device, as well as the effect of oxygen vacancies on its switching ratio and memory, and summarized the conclusions.

Keywords: aqueous solution, oxygen vacancies, switch ratio, thin-film transistor(TFT)

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Authors: Khairul Anuar, Wai Yee Lee, Daniel C. S. Bien, Hing Wah Lee, Ishak Azid

Abstract:

This paper investigates the effect of ultrasonic treatment on ZnO nutrient solution prior to the growth of ZnO nanorods, where the seed layer is annealed at 50 and 100°C. The results show that the ZnO nanorods are successfully grown on the sample annealed at 50°C in the sonicated ZnO nutrient solution with a length and a diameter of approximately 8.025 µm and 92 nm, respectively. However, no ZnO nanorods structures are observed for the sample annealed at 50°C and grown in unsonicated ZnO nutrient solution. Meanwhile, the ZnO nanorods for the sample annealed at 100°C are successfully grown in both sonicated and unsonicated ZnO nutrient solutions. The length and diameter of the nanorods for the sample grown in the sonicated solution are 8.681 µm and 1.033 nm, whereas those for the sample grown in the unsonicated solution are 7.613 µm and 1.040 nm. This result shows that with ultrasonic treatment, the length of the ZnO nanorods increases by 14%, whereas their diameter is reduced by 0.7%, resulting in an increase of aspect ratio from 7:1 to 8:1. Electroconductivity and pH sensors are used to measure the conductivity and acidity level of the sonicated and unsonicated solutions, respectively. The result shows that the conductivity increases from 87 mS/cm to 10.4 mS/cm, whereas the solution pH decreases from 6.52 to 6.13 for the sonicated and unsonicated solutions, respectively. The increase in solution conductivity and acidity level elucidates the higher amount of zinc nutrient in the sonicated solution than in the unsonicated solution.

Keywords: ultrasonic treatment, low annealing temperature, ZnO nanostructure, nanorods

Procedia PDF Downloads 346

Authors: Saleh Alkarri, Melinda Frame, Dimple Sharma, John Cairney, Lee Maddan, Jin H. Kim, Jonathan O. Rayner, Teresa M. Bergholz, Muhammad Rabnawaz

Abstract:

Reported herein is an investigation of anti-bacterial and anti-virus properties, mode of action of Mg(OH)₂ and copper-infused Mg(OH)₂ nanoplatelets (NPs) on melt-compounded and thermally embossed polypropylene (PP) surfaces. The anti-viral activity for the NPs was studied in aqueous liquid suspensions against SARS-CoV-2, and the mode of action was investigated on neat NPs and PP samples that were thermally embossed with NPs. Anti-bacterial studies for melt-compounded NPs in PP confirmed approximately 1 log reduction of E. coli populations in 24 h, while for thermally embossed NPs, an 8 log reduction of E. coli populations was observed. In addition, the NPs exhibit anti-viral activity against SARS-CoV-2. Fluorescence microscopy revealed that reactive oxygen species (ROS) is the main mode of action through which Mg(OH)₂ and Cu-Infused Mg(OH)₂act against microbes. Plastics with anti-microbial surfaces from where biocides are non-leachable are highly desirable. This work provides a general fabrication strategy for developing anti-microbial plastic surfaces.

Keywords: anti-microbial activity, E. coli K-12 MG1655, anti-viral activity, SARS-CoV-2, copper-infused magnesium hydroxide, non-leachable, ROS, compounding, surface embossing, dyes

Procedia PDF Downloads 43

Authors: Amal Aljohani, Ahmed Iraqi

Abstract:

Emitting materials with thermally activated delayed fluorescence (TADF) properties as the third generation of organic light-emitting diodes (OLEDs) have received much attention as a modern class of highly efficient emitters because such properties enable the harvesting of both singlet and triplet excitons in EL applications without the doping with complexes of scarce noble metals such as platinum and iridium. Improved molecular design of TADF molecules and applied materials exhibiting internal electroluminescence (EL) with quantum efficiencies of nearly 100% has been achieved being. A2B3 hyperbranched polymers based on new derivatives containing silane core units serving as host materials for thermally activated delayed fluorescence (TADF) guest molecules have been designed and synthesized through several steps, including the synthesis of tetrakis(4-bromophenyl)silane, bis(4-(9H-carbazol-9-yl)phenyl)bis(4-bromophenyl)silane,bis(4-(9H-carbazol-9 yl)phenyl)bis(4-methoxyphenyl)silane and bis(4-(9H-carbazol-9-yl)phenyl)bis(4hydroxyphenyl)silane. This monomer has been used successfully used along with 1,1,1-tri-(p-tosyloxymethyl)-propane to prepare A2B3 hyperbranched polymers via step-growth polymerization. The characterization and the properties of these new host polymers will be presented and discussed in this contribution.

Keywords: carbazole, organic light emitting diodes, thermally activated delayed fluorescence, donor-acceptor, host and guest interaction

Procedia PDF Downloads 121