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Articles 5881 - 5910 of 16796

Full-Text Articles in Materials Science and Engineering

Experimental Determination Of The (0/−) Level For Mg Acceptors In Β-Ga2O3 Crystals, Christopher A. Lenyk, Timothy D. Gustafson, Sergey A. Basun, Larry E. Halliburton, Nancy C. Giles Apr 2020

Experimental Determination Of The (0/−) Level For Mg Acceptors In Β-Ga2O3 Crystals, Christopher A. Lenyk, Timothy D. Gustafson, Sergey A. Basun, Larry E. Halliburton, Nancy C. Giles

Faculty Publications

Electron paramagnetic resonance (EPR) is used to experimentally determine the (0/−) level of the Mg acceptor in an Mg-doped β-Ga2O3 crystal. Our results place this level 0.65 eV (±0.05 eV) above the valence band, a position closer to the valence band than the predictions of several recent computational studies. The crystal used in this investigation was grown by the Czochralski method and contains large concentrations of Mg acceptors and Ir donors, as well as a small concentration of Fe ions and an even smaller concentration of Cr ions. Below room temperature, illumination with 325 nm laser light …

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Poly(Vinyl Alcohol)/Α-Chitin/Nanocellulose Composites Developed From Oil Palm Empty Fruit Bunch (Opefb) For Removal Of Cationic Dyes, Chun Fah Mok Apr 2020

Poly(Vinyl Alcohol)/Α-Chitin/Nanocellulose Composites Developed From Oil Palm Empty Fruit Bunch (Opefb) For Removal Of Cationic Dyes, Chun Fah Mok

Student Works (2020-2029)

In search of an eco-friendly polymeric adsorbent for dye effluent treatment application, poly(vinyl alcohol) (PVA)/chitin/nanocellulose composites were synthesized. The composites were reinforced by oil palm empty fruit bunch fibers (OPEFB)-derived nanocrystalline cellulose (NCC). With addition of 1 wt.% NCC, a maximum improvement of 57.64% and 50.66% in tensile strength and Young’s Modulus were achieved, respectively. However, the PVA-based composites exhibited low resistance in aqueous medium. Hence, maleic acid (MA) was incorporated, in view of modifying PVA-based composites through cross-linking reactions. The effect of varying chitin content (10 wt.%-30 wt.%) and MA content (10%-50% based on total solid content of composite) …

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Development Of B-Type And Multi-Ion Doped Carbonated Hydroxyapatite Bioceramics, Safarzadeh Marjan Apr 2020

Development Of B-Type And Multi-Ion Doped Carbonated Hydroxyapatite Bioceramics, Safarzadeh Marjan

Student Works (2020-2029)

The present research is aimed to investigate the effect of varying the carbonate to phosphate (CO32−/ PO43‒) molar ratios from 0.5 to 5 on the physical and mechanical properties of carbonated hydroxyapatite (CHA) synthesized by a wet chemical method. The sintering was performed under dry carbon dioxide atmosphere at 900 °C to maintain the B-type CHA structure. It was found that increases in CO32−/ PO43‒ ratio was accompanied by an increase in the c/a lattice ratio. The diffraction peaks of the synthesized 0.5-5 CHA powders exhibited a single phase material except for 5CHA which revealed the some minor calcite or …

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Energy Conservation With Open Source Ad Blockers, Joshua M. Pearce Mar 2020

Energy Conservation With Open Source Ad Blockers, Joshua M. Pearce

Michigan Tech Publications, Part 1

Internet-related electricity consumption is rising rapidly as global Internet users spend more than 6.5 h per day online. Open source ad blockers have the potential to reduce the time and thus electricity spent using computers by eliminating ads during Internet browsing and video streaming. In this study, three open source ad blockers are tested against a no-ad blocker control. Page load time is recorded for browsing a representative selection of the globally most-accessed websites, and the time spent watching ads on videos is quantified for both trending and non-trending content. The results show that page load time dropped 11% with …

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Influence Of Glass Fiber Reinforced Polymer Wraps On Corrosion Progression Of Bridge Piles In Marine Environments, Shayan Yazdani Mar 2020

Influence Of Glass Fiber Reinforced Polymer Wraps On Corrosion Progression Of Bridge Piles In Marine Environments, Shayan Yazdani

USF Tampa Graduate Theses and Dissertations

The Friendship Trail Bridge connecting Tampa to St. Petersburg was demolished in 2016. Thirteen 20 inches. by 20 inches. reinforced concrete piles supporting its superstructure were part of research studies conducted between 2004 and 2008 to explore the role of glass fiber reinforced polymers (GFRP) in corrosion repair. During demolition, piles were typically cut at the pile cap and in the splash zone. The resulting segments varied in length between 3 to 4 ft. These remnants were transported to the University of South Florida (USF) campus for postmortem analysis. The overarching goal was to establish the role of GFRP in …

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Dynamic Micromechanical Fabry-Perot Cavity Sensors Fabricated By Multiphoton Absorption Onto Optical Fiber Tips, Jeremiah C. Williams Mar 2020

Dynamic Micromechanical Fabry-Perot Cavity Sensors Fabricated By Multiphoton Absorption Onto Optical Fiber Tips, Jeremiah C. Williams

Theses and Dissertations

This research leveraged two-photon polymerization microfabrication to integrate dynamic mechanical components with Fabry-Perot resonators onto the ends of low-loss optical fibers to prototype 3 micro-optic devices. The first device featured a multi-positional mirror that enabled thin-film deposition onto cavities of any length with mirrors of significant curvature, for refractive index sensing. The second device combined an FP cavity with a spring body featuring easily scalable stiffness for pressure sensing. The third device presented a high-speed rotating micro-anemometer for measuring a wide range of gas flows. All devices represent a significant reduction in size and weight over commercially available devices.

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Investigation Of Ultem 9085 For Use In Printed Orbital Structures, William R. Gallagher Mar 2020

Investigation Of Ultem 9085 For Use In Printed Orbital Structures, William R. Gallagher

Theses and Dissertations

Additive manufacturing is revolutionizing industries ranging from medicine to space. However, the structural characteristics of plastic parts created by these methods are not as well understood as their more established counterparts. This research explored two relevant areas: how the structural characteristics of ULTEM 9085 plastic behaved after exposure to orbital conditions and the design of the cross-sectional area of a beam to be 3-D printed in microgravity based on the expected loads from the printer. To study orbital effects, ULTEM 9085 was printed into 1/4th scale ASTM D638- 14 dogbones using a Stratasys 450mc printer. These dogbones were placed in …

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Wideband Metasurface Antenna, Thomas A. Lepley Mar 2020

Wideband Metasurface Antenna, Thomas A. Lepley

Theses and Dissertations

This effort explored design of metasurface antennas and evaluated their suitability for ultra-wideband applications (2 to 18 GHz). Six unit cell types were characterized. Eigenmode simulations produced frequency vs. phase data for the unit cells, from which impedance vs. gap size data was computed. A holographic design equation was used to generate the metasurface antenna designs. The unit cell simulations revealed that the assumption of single mode operation is a constraint for wideband designs. An 8" by 8" metasurface antenna with a Rogers 3010 dielectric and a design frequency of 10 GHz was fabricated and tested. It had a 1.5:1 …

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Alternate Materials For High-Speed Projectile Casing, Andrew W. Beard Mar 2020

Alternate Materials For High-Speed Projectile Casing, Andrew W. Beard

Theses and Dissertations

A high-speed projectile impact is a highly complex dynamic problem that can be simplified with the use of finite element analysis solvers. Abaqus/Explicit was used to evaluate the impact of various projectiles using a plane strain setup. Using a baseline stainless steel projectile, the proposed sandwich construction design was analyzed and compared to the baseline projectile. The overall goal was to see if a new composite casing could perform similarly to the simple baseline projectile. The sandwich construction used stainless steel, tungsten, and silicon-carbide reinforce aluminum as outer and inner shell materials. The core material was created using additive manufacturing …

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Structural And Electronic Properties Of The Pure And Stable Elemental 3d Topological Dirac Semimetal Α-Sn, Maya N. Nair, Ivan Madarevic, Umamahesh Thupakula, Gertjan Lippertz, Niels Claessens, Pin-Cheng Lin, Harsh Bana, Sara Gonzalez, Giovanni Di Santo, Luca Petaccia, Lino M.C. Pereira, Chris Van Haesendonck, Margriet J. Van Bael Mar 2020

Structural And Electronic Properties Of The Pure And Stable Elemental 3d Topological Dirac Semimetal Α-Sn, Maya N. Nair, Ivan Madarevic, Umamahesh Thupakula, Gertjan Lippertz, Niels Claessens, Pin-Cheng Lin, Harsh Bana, Sara Gonzalez, Giovanni Di Santo, Luca Petaccia, Lino M.C. Pereira, Chris Van Haesendonck, Margriet J. Van Bael

Advanced Science Research Center

In-plane compressively strained α-Sn films have been theoretically predicted and experimentally proven to possess non-trivial electronic states of a 3D topological Dirac semimetal. The robustness of these states typically strongly depends on purity, homogeneity, and stability of the grown material itself. By developing a reliable fabrication process, we were able to grow pure strained α-Sn films on InSb(100), without heating the substrate during growth nor using any dopants. The α-Sn films were grown by molecular beam epitaxy, followed by experimental verification of the achieved chemical purity and structural properties of the film’s surface. Local insight into the surface morphology was …

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Cyclic Regeneration Of Nanostructured Composites For Catalytic Applications, Fatih Dogan Mar 2020

Cyclic Regeneration Of Nanostructured Composites For Catalytic Applications, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

A cermet catalyst material, defining a matrix having interconnected open pores, the matrix selected from the group consisting of YSZ and CGO and defining a substrate, a ceramic coating having a general formula AyBnOx at least partially coating the pores, and a plurality of metal particles A at least partially embedded in the ceramic coating. A is selected from the group consisting of Co, Cu, Ce, Ni, Ti, and combinations thereof and B is selected from the group consisting of Mo, W, Ce, and combinations thereof. When the coating is in a first oxidizing atmosphere …

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A Novel Self-Healing System: Towards A Sustainable Porous Asphalt, Shi Xu, Xueyan Liu, Amir Tabakovic, Erik Schlangen Mar 2020

A Novel Self-Healing System: Towards A Sustainable Porous Asphalt, Shi Xu, Xueyan Liu, Amir Tabakovic, Erik Schlangen

Articles

Self-healing asphalt, aimed to produce a sustainable asphalt pavement using green technology, has been studied in the past two decades. Technologies including encapsulated rejuvenator and induction heating have been proposed, demonstrated in the laboratory, and gradually evaluated in field application. This paper looks into the synergy effect of the above two technologies, where induction heating serves as the asphalt damage repair mechanism, requiring just 2 min heating time and encapsulated rejuvenator will replenish (rejuvenate) aged asphalt binder and reinstate bitumen’s healing ability. Moreover, the increased temperature from induction heating could in turn accelerate the diffusion process of rejuvenator into aged …

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Characterization Of A Sagnac Loop Mirror-Based Hybrid Passive Variable Optical Coupler/Attenuator, Simeon Bikorimana, Muhammad A. Ummy, Abdullah Hossain, Richard Lin, Roger Dorsinville Mar 2020

Characterization Of A Sagnac Loop Mirror-Based Hybrid Passive Variable Optical Coupler/Attenuator, Simeon Bikorimana, Muhammad A. Ummy, Abdullah Hossain, Richard Lin, Roger Dorsinville

Publications and Research

The implementation and performance of a unidirectional all-single mode fiber hybrid passive variable optical coupler/attenuator based on a Sagnac loop mirror with a continuous variable coupling ratio using off-the-shelf optical sub-components are discussed. Parameters of two output ports of the unidirectional hybrid passive variable optical coupler/attenuator, such as maximum coupling ratio, insertion loss, excess loss, and wavelength-dependent return loss over the C-band at room temperature are reported. The reflectivity of the Sagnac loop mirror continuously varies from 0.1% to 99.9% by adjusting retarders of a polarization controller. The 3-dB coupling ratio (i.e., 50:50) between the two output ports of the …

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Selection Of Blowing Agent For Metal Foam Production: A Review, Ankur Bisht, Brijesh Gangil, Vinay Kumar Patel Mar 2020

Selection Of Blowing Agent For Metal Foam Production: A Review, Ankur Bisht, Brijesh Gangil, Vinay Kumar Patel

Journal of Metals, Materials and Minerals

Metal foams are cellular solids in which gas is uniformly distributed throughout the metal matrix. One of the cheapest ways of evolving the gas is introducing the blowing agent in parent metal in liquid state. A blowing agent is defined as a material that decomposes under the presence of heat and releases gas which then propels the foaming process. The quality of final foam is influenced by several parameters such as composition, size and volume fraction of the blowing agent used. Different chemicals which can evolve gases such as carbonates and metal hydrides fit into the description of blowing agent. …

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An Approach To Search The Potentiality Of Node In Bamboo Strip Reinforced Composites, Mohammad Irfan Iqbal, Rashed Al Mizan, Ayub Nabi Khan Mar 2020

An Approach To Search The Potentiality Of Node In Bamboo Strip Reinforced Composites, Mohammad Irfan Iqbal, Rashed Al Mizan, Ayub Nabi Khan

Journal of Metals, Materials and Minerals

Bamboo has recently entered the composite sector with some attractive labels such as 'green'. The current commercial manufacturing method of bamboo composite removes the node's portion of bamboo culm during bamboo processing. This method generates a high amount of solid waste materials along with processing complexity and the scientific merit of this practice is also questionable. This research investigates the effects of culm nodes on bamboo based composite properties. In this study an approach to produce bamboo strips reinforced epoxy composites and their mechanical properties (e.g. tensile, flexural and impact properties) were reported. It was demonstrated that mechanical properties of …

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Preparation And Characterization Of Lake Pigments From Sappan Wood Using Thai Local Clays, Jitnapa Sirirak, Nattawan Worawannotai, Cheewita Suwanchawalit, Supanee Chayabutra Mar 2020

Preparation And Characterization Of Lake Pigments From Sappan Wood Using Thai Local Clays, Jitnapa Sirirak, Nattawan Worawannotai, Cheewita Suwanchawalit, Supanee Chayabutra

Journal of Metals, Materials and Minerals

Thai local clays: Munpoo clay (MC) and Dindang clay (DC) were utilized as the adsorbents for preparation of the lake pigments from sappan wood. The lake pigment which was prepared by using MC as the adsorbent (L-MC) appeared reddish-brown while a deeper reddish-brown color of the lake pigment (L-DC) was obtained by using DC as the adsorbent. Characterization of MC, DC, L-MC, and L-DC was accomplished by XRD, SEM, FT-IR, BET, TGA and UV-Vis DRS. The effects of adsorbent dosage, pH of sappan wood extract and time on the adsorption were also investigated. The results revealed that silicon oxide and …

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Poly(Ester Urethane)-Crosslinked Carboxymethylchitosan As A Highly Water Swollen Hydrogel, Nunthiya Deepuppha, Apiwat Kadnaim, Boonjira Rutnakornpituk, Metha Rutnakornpituk Mar 2020

Poly(Ester Urethane)-Crosslinked Carboxymethylchitosan As A Highly Water Swollen Hydrogel, Nunthiya Deepuppha, Apiwat Kadnaim, Boonjira Rutnakornpituk, Metha Rutnakornpituk

Journal of Metals, Materials and Minerals

This work focused on the synthesis and characterization of carboxymethylchitosan (CMC)-based hydrogels modified with polyester-containing polyurethane (PU). The polyester was first synthesized from the condensation between 1,6-hexane diol and malonic acid, then reacted with an excess of 1,6-hexamethylene diisocyanate (HDI), and followed by the reaction with ethylene glycol as a chain extender to gain PU. CMC was chemically crosslinked with a water soluble crosslinker in the presence of 1-60 wt% of PU to obtain highly water swollen CMC hydrogels. Upon addition of PU, the CMC hydrogel showed excellent water swellability (up to 400 times of the dried weight), and it …

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The Luminescence, Optical, And Structural Properties Of Srmoo4:Ce3+ Phosphor For Photonics Material Applications, Eakgapon Kaewnuam, Nuanthip Wantana, Sasithorn Saikaew, Jakrapong Kaewkhao Mar 2020

The Luminescence, Optical, And Structural Properties Of Srmoo4:Ce3+ Phosphor For Photonics Material Applications, Eakgapon Kaewnuam, Nuanthip Wantana, Sasithorn Saikaew, Jakrapong Kaewkhao

Journal of Metals, Materials and Minerals

SrMoO4:Ce3+ phosphors with different Ce2O3 concentration were studied in the structure, optical and luminescence properties. The phosphor powders were synthesized by a solid-state reaction to investigate with the XRD, FTIR, absorption and emission spectra measurement. The XRD patterns confirm the tetragonal crystalline structure of SrMoO4 host composition. The FTIR spectra show the dominant vibrations of tetrahedral [MoO4]2- unit in powders. These phosphors absorb photons in the range of ultraviolet and visible light proved by the absorption spectra. The emission spectra represent the strongest emission at 421 nm wavelength of phosphors under 266 nm excitation. This emission occurred under the transition …

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Defects Of The Steel Billet In Continuous Casting, Anh-Hoa Bui, Van-Hung Nguyen Mar 2020

Defects Of The Steel Billet In Continuous Casting, Anh-Hoa Bui, Van-Hung Nguyen

Journal of Metals, Materials and Minerals

In continuous casting process, defects of the steel billet (e.g. crack, pinhole, blowhole, central shrinkage, slag entrapment and appearance deviation, etc.) negatively affect the quality and the yield of rolled products. This research has been carried out to investigate some defects which often occurred in Vietnamese steel plants. The experimental work was conducted in an industrial 4-strands continuous casting machine with the billet's cross-section of 130×130 mm2 . The position, generating cause identification of these defects and proper measures have been discussed. A change in the steel compositions and the water distribution during secondary cooling was applied to improve the …

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Sm3+ Ions Doped Zinc Barium Tellurite Oxyfluoride Glasses For Laser Materials, Yaowalak Yamsuk, Patarawagee Yasaka, Jakrapong Kaewkhao, Narong Sangwaranatee Mar 2020

Sm3+ Ions Doped Zinc Barium Tellurite Oxyfluoride Glasses For Laser Materials, Yaowalak Yamsuk, Patarawagee Yasaka, Jakrapong Kaewkhao, Narong Sangwaranatee

Journal of Metals, Materials and Minerals

The Sm3+ ions were doped tellurite glasses with composition (55-x) TeO2-10ZnF2- 35BaO-xSm2O3 (where x = 0.00, 0.05, 0.10, 0.50, 1.00 and 1.50 in mol%) to investigate the physical, the optical, the luminescence and structural properties. The functional groups can be identified using FT-IR spectra of Sm3+ in the glasses. The most intense peak from emission spectra is at 600 nm (4G5/26H7/2) corresponding to reddish-orange color. The oscillator strengths were resolved from the absorption spectra and then used to calculate the Judd - Ofelt (J - O) intensity parameters. The radiative properties were calculated by J - O intensity parameters for …

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The Water Permeability Properties Of Re-Vibrated Lightweight Concrete, Muayad Mohammed Kassim Mar 2020

The Water Permeability Properties Of Re-Vibrated Lightweight Concrete, Muayad Mohammed Kassim

Journal of Metals, Materials and Minerals

Re-vibration of sequential layers of relatively deep structural members after a particular time harms the strength and water permeability properties of the concrete. The harmful effects can be observed in lightweight concrete due to the floating tendency of lightweight aggregate. In this experimental study, the influence of adding retarder plasticizer and silica fume on water permeability properties of re-vibrated lightweight concrete was investigated. The effects of re-vibration at different time lags on compressive strength and permeable voids ratio were studied. Absorption, sorptivity, and water penetration depth under pressure were also studied. Results show that the addition of a retarder increased …

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Physical Property And Compressive Strength Of Fired Clay Bricks Incorporated With Paper Waste, Anuwat Srisuwan, Nonthaphong Phonphuak Mar 2020

Physical Property And Compressive Strength Of Fired Clay Bricks Incorporated With Paper Waste, Anuwat Srisuwan, Nonthaphong Phonphuak

Journal of Metals, Materials and Minerals

This research is intended to evaluate the effects of paper waste addition on the physical properties and strength of fired clay bricks. Paper waste was mixed with clay in the ratios of 2.5, 5.0, 7.5 and 10 wt%. Green bricks were fired with different variations of temperature from 900-1100C for1 h in air. Fired bricks were then analyzed for physical and mechanical properties. Porosity was increased with higher paper waste content. An increase in porosity relatedly created lower density and higher shrinkage values. Additionally, porous content in fired clay bricks correlated to the deterioration of the compressive strength, due to …

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Structural Studies Of Natural Zeolites And Optimizations For Water Hardness Softening Media, Tesfamariam Teklu Gebretsadik, Teklit Kidane Gebremedhin Mar 2020

Structural Studies Of Natural Zeolites And Optimizations For Water Hardness Softening Media, Tesfamariam Teklu Gebretsadik, Teklit Kidane Gebremedhin

Journal of Metals, Materials and Minerals

This study was aimed at investigating the mineralogical composition and structural features of natural zeolites using XRF, XRD, TGA, FT-IR and SEM. Natural zeolites were subjected to acid-activation and subsequently with NaCl salt to enhance surface area for water hardness softening applications. Peaks around 3560 and 1650 cm-1 belongs to O - H stretching and O - H bending vibrations which confirmed the presence of moisture within zeolite structures. This result was further supported by evolution of moisture above 108°C from thermogravimetric analysis. Fibrous structures which are full of rough texture were examined by SEM. The XRD pattern confirmed Stellerite …

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Biomimetic Metal-Organic Nanoparticles Prepared With A 3d-Printed Microfluidic Device As A Novel Formulation For Disulfiram-Based Therapy Against Breast Cancer, Ya Chang, Jizong Jiang, Wu Chen, Wen Yang, Lili Chen, Pengyu Chen, Jianzhong Shen, Shizhi Qian, Teng Zhou, Linfeng Wu, Liang Hong, Yongzhuo Huang, Feng Li Mar 2020

Biomimetic Metal-Organic Nanoparticles Prepared With A 3d-Printed Microfluidic Device As A Novel Formulation For Disulfiram-Based Therapy Against Breast Cancer, Ya Chang, Jizong Jiang, Wu Chen, Wen Yang, Lili Chen, Pengyu Chen, Jianzhong Shen, Shizhi Qian, Teng Zhou, Linfeng Wu, Liang Hong, Yongzhuo Huang, Feng Li

Mechanical & Aerospace Engineering Faculty Publications

Disulfiram (DSF) is currently tested in several clinical trials for cancer treatment in combination with cop-per (Cu) ions. Usually, DSF and Cu are administered in two separate formulations. In the body, DSF andCu ions form diethyldithiocarbamate copper complex [Cu(DDC)2] which has potent antitumor activities.However, the “two formulation” approach often achieved low Cu(DDC)2 concentration at tumor regions and resulted in compromised anticancer efficacy. Therefore, preformed Cu(DDC)2 complex administered in a single formulation will have better anticancer efficacy. However, the poor aqueous solubility of Cu(DDC)2 is a significant challenge for its clinical use. In this work, a …

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Development Of Sr/Cao Catalyst Derived From Cuttlebone (Sepia Officinalis) For Biodiesel Production, Napat Tomano, Apisit Prokaew, Supakorn Boonyuen, Sarute Ummartyotin Mar 2020

Development Of Sr/Cao Catalyst Derived From Cuttlebone (Sepia Officinalis) For Biodiesel Production, Napat Tomano, Apisit Prokaew, Supakorn Boonyuen, Sarute Ummartyotin

Journal of Metals, Materials and Minerals

Cuttlebone (Sepia officinalis) was used as a source of calcium oxide for biodiesel catalyst. The objective of this work is to present the bio-based catalyst prepared from cuttlebone. 1, 3, 5 and 10 %wt of strontium was loaded into calcium oxide powder derived from cuttlebone. Structural properties of Sr/CaO catalyst were evaluated by Fourier transform infrared and X-ray diffraction, respectively. There is no change on morphological properties of catalyst between Sr/CaO and pristine CaO. The homogeneous distribution of strontium was confirmed by EDX mapping technique. The specific surface area of powder was estimated to be 10-30 m2 ·g-1. The thermal …

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Investigation Of Crosslink Structure Of Natural Rubber During Vulcanization Using X-Ray Absorption Near Edge Spectroscopy, Kanoktip Boonkerd, Wanwisa Limphirat Mar 2020

Investigation Of Crosslink Structure Of Natural Rubber During Vulcanization Using X-Ray Absorption Near Edge Spectroscopy, Kanoktip Boonkerd, Wanwisa Limphirat

Journal of Metals, Materials and Minerals

The X-ray absorption near edge spectroscopy technique (XANES) has been applied to determine the crosslinking structure of natural rubber (NR) during sulfur vulcanization process. The NR samples were prepared using DCBS as an accelerator at different sulfur to DCBS ratios (from 0.26 to 6.67). The results showed that with increasing cure time from tc50 to tc70, tc90 and tc100 the position of sulfur peak shifted to higher energy. This implied that the amount of polysulfidic crosslink gradually decreased with increasing cure time. This result supported the crosslinking mechanism proposed in the literature at which the polysulfidic crosslink is dominating at …

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Influence Of Poly(Butylene Terephthalate) And Wollastonite On Properties Of Recycled Poly(Ethylene Terephthalate) Preforms, Phasawat Chaiwutthinan, Thaksaporn Riyaphan, Athapon Simpraditpan, Amnouy Larpkasemsuk Mar 2020

Influence Of Poly(Butylene Terephthalate) And Wollastonite On Properties Of Recycled Poly(Ethylene Terephthalate) Preforms, Phasawat Chaiwutthinan, Thaksaporn Riyaphan, Athapon Simpraditpan, Amnouy Larpkasemsuk

Journal of Metals, Materials and Minerals

Influence of poly(butylene terephthalate) (PBT) and wollastonite (WLN) on properties of recycled poly(ethylene terephthalate) (RPET) was investigated. RPET was first melt-mixed with PBT at five loadings (10-50 wt%) on a twin screw extruder, and then injection molded. Scanning electron micrographs showed the immiscible blends. The blends at 10-40 wt% PBT displayed droplet-matrix morphology, while the blend at 50 wt% PBT showed a matrix inversion. All blends showed a PBT-dosedependent increase in impact strength and Young's modulus with an expense of tensile strength and elongation at break. Among five RPET/PBT blends, the one at 40 wt% PBT exhibited the good balanced …

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The Design Of A Continuous Wave Molecular Nitrogen Stimulated Raman Laser In The Visible Spectrum, Timothy J. Bate Mar 2020

The Design Of A Continuous Wave Molecular Nitrogen Stimulated Raman Laser In The Visible Spectrum, Timothy J. Bate

Theses and Dissertations

Hollow-core photonic crystal fibers (HCPCFs) shows promise as a hybrid laser with higher nonlinear process limits and small beam size over long gain lengths. This work focuses on the design of a CW molecular nitrogen (N2) stimulated Raman laser. N2 offers Raman gains scaling up to 900 amg, scaling higher than H2. The cavity experiment showed the need to include Rayleigh scattering in the high pressure required for N2 Raman lasing. Even at relatively low pressure ssuch as 1,500 psi, high conversion percentages should be found if the fiber length is chosen based on …

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Cn And C2 Spectroscopy On The Pulsed Ablation Of Graphite In The Visible Spectrum, Brandon A. Pierce Mar 2020

Cn And C2 Spectroscopy On The Pulsed Ablation Of Graphite In The Visible Spectrum, Brandon A. Pierce

Theses and Dissertations

An experimental study was conducted on the nanosecond pulsed laser ablation of graphite using a KrF laser at a fluence of 3.8 J/cm2 in Air, Ar, He, and N2. Optical emissions spectroscopy revealed the C2 Swan sequences and the CN Violet sequences. A spectroscopic model was developed to extract the molecular rotational and vibrational temperatures of each excited species for t=0.5-10 microseconds after laser irradiation. The rovibrational temperatures were found to vary with background gas for the CN Violet; however, only the vibrational temperature varied between He and the other background gases for C2 Swan. …

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Design, Development, And Testing Of A Low Cost, Additively-Manufactured, Centrifugal Compressor, Aaron P. Bauer Mar 2020

Design, Development, And Testing Of A Low Cost, Additively-Manufactured, Centrifugal Compressor, Aaron P. Bauer

Theses and Dissertations

The three objectives of this research were to: 1.) design, build, and test AM compressors to substitute into COTS micro-gas turbine engines, 2.) provide initial correlations between FEA and compressor failure speed, and 3.) characterize the effects of AM on compressor performance. These goals improved the design cycle cost and the design-validation time cycle. ULTEM 9085, 300-AMB, and Onyx-Kevlar temperature-dependent tensile properties were measured. FEA-predicted failure speeds of stock compressor designs led design improvements, potentially fulfilling the original compressor requirements. Physical testing of the stock and ULTEM 9085 compressors occurred. Comparing these compressors' performances demonstrated that low cost, AM materials …

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