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Records with Subject: Materials
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The Mechanism of the Effect of Al2O3 Content on the Liquid Phase Fluidity of Iron Ore Fines
Heping Li, Shengli Wu, Zhibin Hong, Weili Zhang, Heng Zhou, Mingyin Kou
January 7, 2020 (v1)
Subject: Materials
Keywords: Al2O3, consolidation strength, iron ore fines, liquid phase fluidity
The sintering process is significantly important for the ironmaking in China because of the large amount of sinter consumed. Al2O3 is an important element determining the quality and quantity of sinter. However, different conclusions have been made regarding the effects of Al2O3 on the amount and fluidity of the liquid phase formed in the sinter phase. Therefore, it is necessary to examine the effects of Al2O3 content on the amount and fluidity of the liquid phase. The present work investigated the effects of different Al2O3 contents of iron ore fines on the liquid phase formation, mineral composition, and consolidation strength. The results showed that a small amount of Al2O3 increased the amount of calcium ferrite, making the liquid phase formation easier. As the Al2O3 content in iron ore fines increased, the liquidity index decreased continuously, while the fluidity and the consolidation strength of the sintered body were directly related to the content squared. The quality of the s... [more]
Role of Ionic Headgroups on the Thermal, Rheological, and Foaming Properties of Novel Betaine-Based Polyoxyethylene Zwitterionic Surfactants for Enhanced Oil Recovery
Muhammad Shahzad Kamal, Syed Muhammad Shakil Hussain, Lionel Talley Fogang
January 7, 2020 (v1)
Subject: Materials
Keywords: foam, polymer, polyoxyethylene, rheology, thermal stability
Long-term thermal stability of surfactants under harsh reservoir conditions is one of the main challenges for surfactant injection. Most of the commercially available surfactants thermally degrade or precipitate when exposed to high-temperature and high-salinity conditions. In this work, we designed and synthesized three novel betaine-based polyoxyethylene zwitterionic surfactants containing different head groups (carboxybetaine, sulfobetaine, and hydroxysulfobetaine) and bearing an unsaturated tail. The impact of the surfactant head group on the long-term thermal stability, foam stability, and surfactant−polymer interactions were examined. The thermal stability of the surfactants was assessed by monitoring the structural changes when exposed at high temperature (90 °C) for three months using 1H-NMR, 13C-NMR, and FTIR analysis. All surfactants were found thermally stable regardless of the headgroup and no structural changes were evidenced. The surfactant−polymer interactions were domin... [more]
Copper Adsorption by Magnetized Pine-Needle Biochar
Eleni Nicolaou, Katerina Philippou, Ioannis Anastopoulos, Ioannis Pashalidis
January 7, 2020 (v1)
Subject: Materials
Keywords: copper adsorption, FTIR and XRD studies, isotherms, kinetics, magnetized pine needle biochar
The Cu(II) adsorption from aqueous solutions by magnetic biochar obtained from pine needles has been studied by means of batch-type experiments. The biochar fibers have been magnetized prior (pncm: carbonized-magnetized pine needles) and after oxidation (pncom: carbonized-oxidized-magnetized pine needles) and have been used as adsorbents to study the presence of carboxylic moieties on the magnetization and following adsorption process. The effect of pH (2−10), initial metal concentration (10−5−9·10−3 mol·L−1) and contact time (0−60 min) has been studied by varying the respective parameter, and the adsorbents have been characterized by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) measurements prior and after Cu(II)-adsorption. FTIR measurements were performed to investigate the formation of surface species and XRD measurements to record possible solid phase formation and characterize formed solids, including the evaluation of their average crystal size. The data obtaine... [more]
Filtration Performances of Different Polysaccharides in Microfiltration Process
Shujuan Meng, Hongju Liu, Qian Zhao, Nan Shen, Minmin Zhang
January 7, 2020 (v1)
Subject: Materials
Keywords: calcium ion, membrane fouling, microfiltration process, polysaccharides
Membrane technology has been widely applied for water treatment, while membrane fouling still remains a big challenge. The polysaccharides in extracellular polymeric substances (EPS) have been known as a significant type of foulant due to their high fouling propensity. However, polysaccharides have many varieties which definitely behave differently in membrane filtration. Therefore, in this study, different polysaccharides alginate sodium and xanthan gum were chosen to study their effects on membrane fouling in a wide concentration range. The results demonstrated that the filtration behaviors of alginate sodium and xanthan gum were completely different, which was due to their different molecular structures. Alginate had a small molecular weight and it was easy for alginate to penetrate membrane pores resulting in pore blocking. A series of concentrations of alginate including 5 mg/L, 10 mg/L, 20 mg/L, 30 mg/L, 40 mg/L, and 50 mg/L were examined and it was found that the permeate flux d... [more]
Characterization and Beneficiation Options for Tungsten Recovery from Yxsjöberg Historical Ore Tailings
Jane Mulenshi, Pourya Khavari, Saeed Chehreh Chelgani, Jan Rosenkranz
January 6, 2020 (v1)
Subject: Materials
Keywords: beneficiation, characterization, geometallurgical approach, historical tailings, reprocessing, Scheelite, Tungsten
Repositories of historical tungsten mining tailings pose environmental risks, but are also potential resources for valuable metals. They still contain large tonnages of useful minerals and metals, reflecting the inefficient extraction methods and/or low metal prices at the time they were mined. The focus of this study is to evaluate the technical viability of reprocessing the tailings to recover some of the contained valuable minerals and metals, as well as reducing the negative environmental impact associated with the tailings. Geometallurgical studies were conducted on drill core samples taken from the Smaltjärnen tailings repository of the closed Yxsjöberg tungsten mine, Sweden. The collected samples were characterized physically, chemically, and mineralogically. Knelson concentrator dry low- and high-intensity magnetic separation methods were tested as potential beneficiation methods. The tailings are dominated by the −600 to +149 µm particles. The highest concentration of tungsten... [more]
Preparation of KOH and H3PO4 Modified Biochar and Its Application in Methylene Blue Removal from Aqueous Solution
Li Liu, Yang Li, Shisuo Fan
January 6, 2020 (v1)
Subject: Materials
Keywords: Adsorption, corn stalk biochar, H3PO4 modification, KOH modification, Methylene blue
Improperly treated or directly discharged into the environment, wastewater containing dyes can destroy the quality of water bodies and pollute the ecological environment. The removal of dye wastewater is urgent and essential. In this study, corn stalk was pyrolyzed to pristine biochar (CSBC) in a limited oxygen atmosphere and modified using KOH and H3PO4 (KOH-CSBC, H3PO4-CSBC, respectively). The biochars were characterized by surface area and pore size, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), as well as their behavior in adsorbing methylene blue (MB). Results indicated that the pore structure of CSBC became more developed after modification by KOH. Meanwhile, H3PO4-CSBC contained more functional groups after activation treatment. The pseudo-second-order kinetic and the Langmuir adsorption isotherm represented the adsorption process well. The maximum MB adsorption capacity of CSBC, KOH-CSBC, and H3PO4-CSBC was 43.1... [more]
CoFe2O4 Nanomaterials: Effect of Annealing Temperature on Characterization, Magnetic, Photocatalytic, and Photo-Fenton Properties
Nguyen Thi To Loan, Nguyen Thi Hien Lan, Nguyen Thi Thuy Hang, Nguyen Quang Hai, Duong Thi Tu Anh, Vu Thi Hau, Lam Van Tan, Thuan Van Tran
January 2, 2020 (v1)
Subject: Materials
Keywords: cobalt ferrite, magnetic properties, photocatalytic activity, rhodamine B, solution combustion method
In this research, structural, magnetic properties and photocatalytic activity of cobalt ferrite spinel (CoFe2O4) nanoparticles were studied. The samples were characterized by X-ray powder diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), transmission electronic microscopy (TEM), Brunauer−Emmett−Teller (BET), Fourier transform infrared spectroscopy (FTIR), and UV-visible diffused reflectance spectroscopy (DRS) analysis. The XRD analysis revealed the formation of the single-phase CoFe2O4 with a cubic structure that is annealed at 500−700 °C in 3 h. The optical band gap energy for CoFe2O4 was determined to be in the range of 1.57−2.03 eV. The effect on the magnetic properties of cobalt ferrites was analyzed by using a vibrating sample magnetometer (VSM). The particle size and the saturation magnetization of cobalt ferrite nanoparticles increased with increasing annealing temperature. The photocatalytic activity of CoFe2O4 nanoparticles was investigated... [more]
Fretting Wear in Orthodontic and Prosthetic Alloys with Ti(C, N) Coatings
Katarzyna Banaszek, Leszek Klimek, Jan Ryszard Dąbrowski, Wojciech Jastrzębski
January 2, 2020 (v1)
Subject: Materials
Keywords: dental alloys, fretting, fretting wear, Ni-Cr-Mo, Ti(C, N) coating, titaniumcarbonitride
Fretting occurs during orthodontic treatment or wearing prosthesis. Although weight of particles is marginal, the total releasing area is more of a concern due to amount and volume of molecules. The aim of the study was to examine the fretting wear resistance of orthodontic and prosthetic alloy Ni-Cr-Mo samples coated with Ti(C, N) and to compare them with samples without any coating. Five groups of cylindrical shape samples (S1−S5) made of Ni-Cr-Mo were coated with Ti(C, N) layers with different content of C and N. The control group (S0) was without layer. The alloys underwent fretting wear resistance tests with amplitude 100 μm, at frequency 0.8 Hz with averaged unit load: 5, 10, and 15 N for 15 min. The samples were subjected to microscopic observations using scanning electron microscope and a laser scanning microscope. Samples with Ti(C, N) coatings revealed higher fretting wear resistance. The wear in each case with Ti(C, N) coatings was over twice as low. The lowest wear and thus... [more]
Controlled Synthesis of Triangular Silver Nanoplates by Gelatin−Chitosan Mixture and the Influence of Their Shape on Antibacterial Activity
Quoc Khuong Vo, Duc Duy Phung, Quynh Nhu Vo Nguyen, Hong Hoang Thi, Nhat Hang Nguyen Thi, Phuong Phong Nguyen Thi, Long Giang Bach, Lam Van Tan
January 2, 2020 (v1)
Subject: Materials
Keywords: antibacterial activity, gelatin, seeding growth approach, triangular silver nanoplates
Triangular silver nanoplates were prepared by using the seeding growth approach with the presence of citrate-stabilized silver seeds and a mixture of gelatin−chitosan as the protecting agent. By understanding the critical role of reaction components, the synthesis process was improved to prepare the triangular nanoplates with high yield and efficiency. Different morphologies of silver nanostructures, such as triangular nanoplates, hexagonal nanoprisms, or nanodisks, can be obtained by changing experimental parameters, including precursor AgNO3 volume, gelatin−chitosan concentration ratios, and the pH conditions. The edge lengths of triangular silver nanoplates were successfully controlled, primarily through the addition of silver nitrate under appropriate condition. As-prepared triangular silver nanoplates were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), UV-Vis, Fourier transform infrared spectroscopy (FT-IR), and X-Ray diffraction (XRD). Si... [more]
Effect of CuO as Sintering Additive in Scandium Cerium and Gadolinium-Doped Zirconia-Based Solid Oxide Electrolysis Cell for Steam Electrolysis
R. Visvanichkul, S. Peng-Ont, W. Ngampuengpis, N. Sirimungkalakul, P. Puengjinda, T. Jiwanuruk, T. Sornchamni, P. Kim-Lohsoontorn
January 2, 2020 (v1)
Subject: Materials
Keywords: CuO, hydrogen production, sintering additive, solid oxide electrolysis cells, steam electrolysis
The effect of CuO as a sintering additive on the electrolyte of solid oxide electrolysis cells (SOECs) was investigated. 0.5 wt% CuO was added into Sc0.1Ce0.05Gd0.05Zr0.89O2 (SCGZ) electrolyte as a sintering additive. An electrolyte-supported cell (Pt/SCGZ/Pt) was fabricated. Phase formation, relative density, and electrical conductivity were investigated. The cells were sintered at 1373 K to 1673 K for 4 h. The CuO significantly affected the sinterability of SCGZ. The SCGZ with 0.5 wt% CuO achieved 95% relative density at 1573 K while the SCGZ without CuO could not be densified even at 1673 K. Phase transformation and impurity after CuO addition were not detected from XRD patterns. Electrochemical performance was evaluated at the operating temperature from 873 K to 1173 K under steam to hydrogen ratio at 70:30. Adding 0.5 wt% CuO insignificantly affected the electrochemical performance of the cell. Activation energy of conduction (Ea) was 72.34 kJ mol−1 and 74.93 kJ mol−1 for SCGZ and... [more]
Insights into the Fouling Propensities of Natural Derived Alginate Blocks during the Microfiltration Process
Shujuan Meng, Rui Wang, Minmin Zhang, Xianghao Meng, Hongju Liu, Liang Wang
December 16, 2019 (v1)
Subject: Materials
Keywords: fouling propensities, membrane fouling, molecular composition of foulant, transparent exopolymer particles (TEP)
Membrane technology has been one of the most promising techniques to solve the water problem in future. Unfortunately, it suffers from the fouling problem which is ubiquitous in membrane systems. The origin of the bewilderments of the fouling problem lies in the lack of deep understanding. Recent studies have pointed out that the molecular structure of foulant affects its fouling propensity which has been ignored in the past. In this study, the filtration behaviors of alginate blocks derived from the same source were comprehensively explored. Alginate blocks share the same chemical composition but differ from each other in molecular structure. The alginate was first extracted from natural seaweed using calcium precipitation and ion-exchange methods. Extracted alginate was further fractionized into MG-, MM- and GG-blocks and the characteristics of the three blocks were examined by Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) obse... [more]
Characterization and Modelling Studies of Activated Carbon Produced from Rubber-Seed Shell Using KOH for CO2 Adsorption
Azry Borhan, Suzana Yusup, Jun Wei Lim, Pau Loke Show
December 16, 2019 (v1)
Subject: Materials
Keywords: activated carbon, CO2 adsorption, isotherms, kinetics modeling, rubber-seed shell
Global warming due to the emission of carbon dioxide (CO2) has become a serious problem in recent times. Although diverse methods have been offered, adsorption using activated carbon (AC) from agriculture waste is regarded to be the most applicable one due to numerous advantages. In this paper, the preparation of AC from rubber-seed shell (RSS), an agriculture residue through chemical activation using potassium hydroxide (KOH), was investigated. The prepared AC was characterized by nitrogen adsorption−desorption isotherms measured in Micrometrices ASAP 2020 and FESEM. The optimal activation conditions were found at an impregnation ratio of 1:2 and carbonized at a temperature of 700 °C for 120 min. Sample A6 is found to yield the largest surface area of 1129.68 m2/g with a mesoporous pore diameter of 3.46 nm, respectively. Using the static volumetric technique evaluated at 25 °C and 1.25 bar, the maximum CO2 adsorption capacity is 43.509 cm3/g. The experimental data were analyzed using... [more]
Modifying Nanoporous Carbon through Hydrogen Peroxide Oxidation for Removal of Metronidazole Antibiotics from Simulated Wastewater
Teguh Ariyanto, Rut Aprillia Galuh Sarwendah, Yove Maulana Novirdaus Amimmal, William Teja Laksmana, Imam Prasetyo
December 16, 2019 (v1)
Subject: Materials
Keywords: Adsorption, metronidazole, porous carbon, surface modification, wastewater treatment
This study examined change in pore structure and microstructure of nanoporous carbon after surface oxidation and how it affects the adsorption performance of metronidazole antibiotics. The surface oxidation was performed by hydrogen peroxide at 60 °C. The properties of porous carbon were investigated by N2-sorption analysis (pore structure), scanning electron microscopy (surface morphology), the Boehm titration method (quantification of surface functional group), and Fourier transform infrared spectroscopy (type of surface functional group). The results showed that the oxidation of porous carbon by hydrogen peroxide has a minor defect in the carbon pore structure. Only a slight decrease in specific surface area (8%) from its original value (973 m2g−1) was seen but more mesoporosity was introduced. The oxidation of porous carbon with hydrogen peroxide modified the amount of oxide groups i.e., phenol, carboxylic acid and lactone. Moreover, in the application the oxidized carbon exhibited... [more]
Thermophysical Properties and CO2 Absorption of Ammonium-Based Protic Ionic Liquids Containing Acetate and Butyrate Anions
Normawati M. Yunus, Nur Hamizah Halim, Cecilia Devi Wilfred, Thanabalan Murugesan, Jun Wei Lim, Pau Loke Show
December 16, 2019 (v1)
Subject: Materials
Keywords: ammonium-based protic ionic liquids, CO2 absorption, density, thermal expansion coefficient, thermal stability, viscosity
Ionic liquids, which are classified as new solvents, have been identified to be potential solvents in the application of CO2 capture. In this work, six ammonium-based protic ionic liquids, containing ethanolammonium [EtOHA], tributylammonium [TBA], bis(2-ethylhexyl)ammonium [BEHA] cations, and acetate [AC] and butyrate [BA] anions, were synthesized and characterized. The thermophysical properties of the ammonium-based protic ionic liquids were measured. Density, ρ, and dynamic viscosity, η, were determined at temperatures between 293.15 K and 363.15 K. The density and viscosity values were correlated using empirical correlations and the thermal coefficient expansion, αp, and molecular volume, Vm, were estimated using density values. The thermal stability of the ammonium-based protic ionic liquids was investigated using thermogravimetric analyzer (TGA) at a heating rate of 10 °C·min‒1. The CO2 absorption of the ammonium-based ionic liquids were measured up to 20 bar at 298.15 K. From th... [more]
The Engineering of Porous Silica and Hollow Silica Nanoparticles to Enhance Drug-loading Capacity
Ngoc-Tram Nguyen-Thi, Linh Phuong Pham Tran, Ngoc Thuy Trang Le, Minh-Tri Cao, The-Nam Tran, Ngoc Tung Nguyen, Cong Hao Nguyen, Dai-Hai Nguyen, Van Thai Than, Quang Tri Le, Nguyen Quang Trung
December 16, 2019 (v1)
Subject: Materials
Keywords: drug delivery system, high drug loading capacity, hollow mesoporous silica, nanoparticles, porous silica
As a promising candidate for expanding the capacity of drug loading in silica nanoplatforms, hollow mesoporous silica nanoparticles (HMSNs) are gaining increasing attention. In this study, porous nanosilica (PNS) and HMSNs were prepared by the sol-gel method and template assisted method, then further used for Rhodamine (RhB) loading. To characterize the as-synthesized nanocarriers, a number of techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen absorption-desorption isotherms, dynamic light scattering (DLS), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) were employed. The size of HMSN nanoparticles in aqueous solution averaged 134.0 ± 0.3 nm, which could be adjusted by minor changes during synthesis, whereas that of PNS nanoparticles was 63.4 ± 0.6 nm. In addition, the encapsulation of RhB into HMSN nanoparticles to form RhB-loaded nanocarriers (RhB/HMSN) was successful, achieving high loading efficiency... [more]
Effect of Ammonia Activation and Chemical Vapor Deposition on the Physicochemical Structure of Activated Carbons for CO2 Adsorption
Dongdong Liu, Jinming Li, Jiaqi Dong, Song Li, Weizhi Feng, Boyin Jia
December 16, 2019 (v1)
Subject: Materials
Keywords: activated carbons, ammonia activation, chemical vapor deposition, CO2 adsorption, physicochemical structure
Focusing on the bottlenecks of traditional physical activation method for the preparation of activated carbons (ACs), we established a simple and scalable method to control the physicochemical structure of ACs and study their CO2 adsorption performance. The preparation is achieved by ammonia activation at different volume fractions of ammonia in the mixture (10%, 25%, 50%, 75%, and 100%) to introduce the nitrogen-containing functional groups and form the original pores and subsequent chemical vapor deposition (CVD) at different deposition times (30, 60, 90, and 120 min) to further adjust the pore structure. The nitrogen content of ACs-0.1/0.25/0.5/0.75/1 increases gradually from 2.11% to 8.84% with the increase of ammonia ratio in the mixture from 10% to 75% and then decreases to 3.02% in the process of pure ammonia activation (100%), during which the relative content of pyridinium nitrogen (N-6), pyrrolidine (N-5), and graphite nitrogen (N-Q) increase sequentially but nitrogen oxygen... [more]
Physical and Thermal Studies of Carbon-Enriched Silicon Oxycarbide Synthesized from Floating Plants
Guan-Ting Pan, Siewhui Chong, Yi Jing Chan, Timm Joyce Tiong, Jun Wei Lim, Chao-Ming Huang, Pradeep Shukla, Thomas Chung-Kuang Yang
December 16, 2019 (v1)
Subject: Materials
Keywords: floating plants, silica, silicon oxycarbide, SiOC, thermal conductivity
In the present study, amorphous mesoporous silicon oxycarbide materials (SiOC) were successfully synthesized via a low-cost facile method by using potassium hydroxide activation, high temperature carbonization, and acid treatment. The precursors were obtained from floating plants (floating moss, water cabbage, and water caltrops). X-ray diffraction (XRD) results confirmed the amorphous Si−O−C structure and Raman spectra revealed the graphitized carbon phase. Floating moss sample resulted in a rather rough surface with irregular patches and water caltrops sample resulted in a highly porous network structure. The rough surface of the floating moss sample with greater particle size is caused by the high carbon/oxygen ratio (1: 0.29) and low amount of hydroxyl group compared to the other two samples. The pore volumes of these floating moss, water cabbage, and water caltrops samples were 0.4, 0.49, and 0.63 cm3 g−1, respectively, resulting in thermal conductivities of 6.55, 2.46, and 1.14 W... [more]
The Synthesis of N-(Pyridin-2-yl)-Benzamides from Aminopyridine and Trans-Beta-Nitrostyrene by Fe2Ni-BDC Bimetallic Metal−Organic Frameworks
Trinh Duy Nguyen, Oanh Kim Thi Nguyen, Thuan Van Tran, Vinh Huu Nguyen, Long Giang Bach, Nhan Viet Tran, Dai-Viet N. Vo, Tuyen Van Nguyen, Seong-Soo Hong, Sy Trung Do
December 16, 2019 (v1)
Subject: Materials
Keywords: bimetallic metal–organic frameworks, decarboxylative amidation, metal–organic framework
A bimetallic metal−organic framework material, which was generated by bridging iron (III) cations and nickel (II) cations with 1,4-Benzenedicarboxylic anions (Fe2Ni-BDC), was synthesized by a solvothermal approach using nickel (II) nitrate hexahydrate and iron (III) chloride hexahydrate as the mixed metal source and 1,4-Benzenedicarboxylic acid (H2BDC) as the organic ligand source. The structure of samples was determined by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and nitrogen physisorption measurements. The catalytic activity and recyclability of the Fe2Ni-BDC catalyst for the Michael addition amidation reaction of 2-aminopyridine and nitroolefins were estimated. The results illustrated that the Fe2Ni-BDC catalyst demonstrated good efficiency in the reaction under optimal conditions. Based on these results, a reaction mechanism was proposed. When the molar ratio of 2-aminopyridine and trans-β-nitrostyrene was 1:1, and the sol... [more]
Sustainable Design and Engineering: A Relationship Analysis between Digital Destructive and Non-Destructive Testing Process for Lightweight Concrete
Muhammad Ahmed Qurashi, Syyed Adnan Raheel Shah, Muhammad Farhan, Muhammad Taufiq, Waleed Khalid, Hunain Arshad, Muhammad Tayyab, Gullnaz Shahzadi, Muhammad Waseem
December 13, 2019 (v1)
Subject: Materials
Keywords: concrete, EPS-beads, lightweight, non-destructive testing, process, sustainable
The development of sustainable lightweight materials is a promising field solution in this era. The production of sustainable materials by replacing coarse aggregates with some lightweight alternative provides a good quality construction material. In this study, rocky coarse aggregates were replaced by an ultra-lightweight material (i.e., expanded polystyrene beads) to produce an equivalent rock-solid mass of concrete. Using an M15 grade of concrete composition, expanded polystyrene (EPS) beads were added in place of aggregates in amounts ranging from 5% to 40% at a water−cement (w/c) ratio of 0.60. The specimen size as per American Society for Testing and Materials (ASTM) specification was 150 mm in diameter and 300 mm in length. Furthermore, statistical analysis for the relationship study for destructive testing (DT) (i.e., compressive test machine) and non-destructive testing (NDT) (i.e., rebound hammer and ultrasonic pulse velocity (UPV)) has been performed at developed specimens u... [more]
Taste Masking of Nizatidine Using Ion-Exchange Resins
Pattaraporn Panraksa, Kasidech Boonsermsukcharoen, Kyu-Mok Hwang, Eun-Seok Park, Pensak Jantrawut
December 11, 2019 (v1)
Subject: Materials
Keywords: Amberlite, Dowex, electronic tongue, ion-exchange resins, nizatidine
The purpose of this study was to mask the bitter taste of nizatidine (NZD) using cation-exchange resins. Amberlite IRP-69 and Dowex-50 containing cross-linked polystyrene backbones were used. The drug resin complexes were prepared by batch process using drug: resin ratios of 1:1, 1:3, and 1:5. The optimum drug: resin ratio and the time required for maximum percentage drug loading into the complexes were determined. The selected drug-resin complexes were evaluated for morphology, drug release, and taste. The NZD-Dowex complex was obtained at a drug: resin ratio of 1:5 using a stirring time of 1 h in order to get 100% loading of NZD. The NZD-Dowex complex had a spherical shape and smooth texture similar to Dowex resin. The NZD-Dowex complex with a ratio of 1:5 showed that in vitro drug release of 4.27% at 5 min in simulated salivary fluid of pH 6.8 and 99.67% at 1 h in simulated gastric fluid of pH 1.2. NZD’s bitter taste was effectively masked when it formed a complex with Dowex at a ra... [more]
Performance of an Active Micro Direct Methanol Fuel Cell Using Reduced Catalyst Loading MEAs
D.S. Falcão, R.A. Silva, C.M. Rangel, A.M.F.R. Pinto
December 10, 2019 (v1)
Subject: Materials
Keywords: commercial MEAs, experimental studies, low catalyst loading, MicroDMFC
The micro direct methanol fuel cell (MicroDMFC) is an emergent technology due to its special interest for portable applications. This work presents the results of a set of experiments conducted at room temperature using an active metallic MicroDMFC with an active area of 2.25 cm². The MicroDMFC uses available commercial materials with low platinum content in order to reduce the overall fuel cell cost. The main goal of this work is to provide useful information to easily design an active MicroDMFC with a good performance recurring to cheaper commercial Membrane Electrode Assemblies MEAs. A performance/cost analysis for each MEA tested is provided. The maximum power output obtained was 18.1 mW/cm² for a hot-pressed MEA with materials purchased from Quintech with very low catalyst loading (3 mg/cm² Pt⁻Ru at anode side and 0.5 mg/cm² PtB at the cathode side) costing around 15 euros. Similar power values are reported in literature for the same type of micro fuel cells working at higher oper... [more]
Highly Efficient 3rd Generation Multi-Junction Solar Cells Using Silicon Heterojunction and Perovskite Tandem: Prospective Life Cycle Environmental Impacts
René Itten, Matthias Stucki
December 10, 2019 (v1)
Subject: Materials
Keywords: carbon footprint, electricity, greenhouse gas, life cycle assessment (LCA), multi-junction, perovskite, photovoltaics, silicon heterojunction, tandem
In this study, the environmental impacts of monolithic silicon heterojunction organometallic perovskite tandem cells (SHJ-PSC) and single junction organometallic perovskite solar cells (PSC) are compared with the impacts of crystalline silicon based solar cells using a prospective life cycle assessment with a time horizon of 2025. This approach provides a result range depending on key parameters like efficiency, wafer thickness, kerf loss, lifetime, and degradation, which are appropriate for the comparison of these different solar cell types with different maturity levels. The life cycle environmental impacts of SHJ-PSC and PSC solar cells are similar or lower compared to conventional crystalline silicon solar cells, given comparable lifetimes, with the exception of mineral and fossil resource depletion. A PSC single-junction cell with 20% efficiency has to exceed a lifetime of 24 years with less than 3% degradation per year in order to be competitive with the crystalline silicon singl... [more]
Experimental and Theoretical Study of the Interactions between Fe₂O₃/Al₂O₃ and CO
Zhiyong Liang, Wu Qin, Changqing Dong
December 10, 2019 (v1)
Subject: Materials
Keywords: Carbon Dioxide Capture, chemical looping combustion (CLC), density functional theory (DFT), iron oxide
The behavior of Fe₂O₃/Al₂O₃ particles as oxygen carriers (OCs) for CO chemical looping combustion (CLC) under different reaction temperatures (700 °C, 800 °C, 900 °C, and 1000 °C) were tested in a lab-scale fluidized bed and a thermogravimetric analysis (TGA) unit. The results show that the oxygen carrier presents the highest reactivity at 800 °C, even after 30 cycles of redox reaction in a fluidized bed, while more obvious carbon deposition occurred for the case at 700 °C, and agglomeration for the case at 1000 °C. Moreover, the detailed behavior of the prepared Fe₂O₃/Al₂O₃ particle was detected in the TGA apparatus at different reaction temperatures. Furthermore, temperature-programming TGA experiments were performed to investigate the influence of different CO concentrations and CO/CO₂ concentrations on the reaction between CO and OC during the chemical looping combustion processes. Based on these experimental behaviors of the prepared Fe₂O₃/Al₂O₃ during the CLC of CO, the detailed... [more]
Improved Separation and Collection of Charge Carriers in Micro-Pyramidal-Structured Silicon/PEDOT:PSS Hybrid Solar Cells
Yuuki Sugano, Keisuke Sato, Naoki Fukata, Kenji Hirakuri
December 10, 2019 (v1)
Subject: Materials
Keywords: conjugated conducting polymer, inorganic/organic hybrid solar cells, light-harvesting efficiency, photovoltaic performance, pyramidal-structured silicon
Silicon (Si)/organic polymer hybrid solar cells have great potential for becoming cost-effective and efficient energy-harvesting devices. We report herein on the effects of polymer coverage and the rear electrode on the device performance of Si/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hybrid solar cells with micro-pyramidal structures. These hybrid solar cells provided adequate generation of charge carriers owing to the suppression of reflectance to below 13%. Additionally, the separation of the photogenerated charge carriers at the micro-pyramidal-structured Si/PEDOT:PSS interface regions and their collection at the electrodes were dramatically improved by tuning the adhesion areas of the PEDOT:PSS layer and the rear electrode materials, thereby attaining a power conversion efficiency of 8.25%. These findings suggest that it is important to control the PEDOT:PSS coverage and to optimize the rear electrode materials in order to achieve highly efficient separa... [more]
Characterization of the Diamond Wire Sawing Process for Monocrystalline Silicon by Raman Spectroscopy and SIREX Polarimetry
Sindy Würzner, Martin Herms, Thomas Kaden, Hans Joachim Möller, Matthias Wagner
December 10, 2019 (v1)
Subject: Materials
Keywords: amorphous phase, diamond wire, microcrack depth, Raman, silicon, SIREX, stress imaging, stress-induced birefringence, wire cutting ability, wire velocity
A detailed approach to evaluate the sub-surface damage of diamond wire-sawn monocrystalline silicon wafers relating to the sawing process is presented. Residual stresses, the presence of amorphous silicon and microcracks are considered and related to diamond wire velocity and cutting ability. In particular, the degree of amorphization of the wafer surface is analyzed, as it may affect the etching performance (texturing) during solar cell manufacture. Raman spectroscopy and Scanning Infrared Stress Explorer (SIREX) measurements are used independently as non-destructive, contactless optical characterization methods to provide stress imaging with high spatial resolution. Raman mappings show that amorphous silicon layers can occur inhomogeneously across the surface of diamond wire-sawn wafers. The Raman and SIREX results reveal a connection between a higher fraction of the amorphous phase, a more inhomogeneous stress distribution and a lower peak maximum of the stress difference on wafers,... [more]
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