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Showing records 1 to 25 of 168. [First] Page: 1 2 3 4 5 Last
Comparative Study of Mercury(II) Removal from Aqueous Solutions onto Natural and Iron-Modified Clinoptilolite Rich Zeolite
Marin Ugrina, Teja Čeru, Ivona Nuić, Marina Trgo
June 10, 2021 (v1)
Subject: Materials
Keywords: iron-modified zeolite, leaching, mercury(II), natural zeolite, sorption
The contamination of soil and water bodies with mercury from anthropogenic sources such as mining and industry activities causes negative effect for living organisms due to the process of bioaccumulation and biomagnification through the food chain. Therefore, the need for remediation of contaminated areas is extremely necessary and very desirable when it is cost-effective by using low-cost sorbents. This paper compares the sorption abilities of natural and iron-modified zeolite towards Hg(II) ions from aqueous solutions. The influence of pH, solid/liquid ratio (S/L), contact time, and initial concentration on the sorption efficiency onto both zeolites was investigated. At the optimal pH = 2 and S/L = 10, the maximum amount of sorbed Hg(II) is 0.28 mmol/g on the natural zeolite and 0.54 mmol/g on the iron-modified zeolite. It was found that rate-controlling step in mass transfer is intraparticle diffusion accompanied by film diffusion. Ion exchange as a main mechanism, accompanied with... [more]
First Principles Statistical Process Monitoring of High-Dimensional Industrial Microelectronics Assembly Processes
Tiago J. Rato, Pedro Delgado, Cristina Martins, Marco S. Reis
June 10, 2021 (v1)
Keywords: artificial generation of variability, data augmentation, high-dimensional data, Industry 4.0, statistical process monitoring
Modern industrial units collect large amounts of process data based on which advanced process monitoring algorithms continuously assess the status of operations. As an integral part of the development of such algorithms, a reference dataset representative of normal operating conditions is required to evaluate the stability of the process and, after confirming that it is stable, to calibrate a monitoring procedure, i.e., estimate the reference model and set the control limits for the monitoring statistics. The basic assumption is that all relevant “common causes” of variation appear well represented in this reference dataset (using the terminology adopted by the founding father of process monitoring, Walter A. Shewhart). Otherwise, false alarms will inevitably occur during the implementation of the monitoring scheme. However, we argue and demonstrate in this article, that this assumption is often not met in modern industrial systems. Therefore, we introduce a new approach based on the r... [more]
Design of Cyclone Separator Critical Diameter Model Based on Machine Learning and CFD
Donggeun Park, Jeung Sang Go
June 10, 2021 (v1)
Keywords: computational fluid dynamics (CFD), critical diameter, cyclone separator, Machine Learning, unsteady RANS
In this paper, the characteristics of the cyclone separator was analyzed from the Lagrangian perspective for designing the important dependent variables. The neural network network model was developed for predicting the separation performance parameter. Further, the predictive performances were compared between the traditional surrogate model and the developed neural network model. In order to design the important parameters of the cyclone separator based on the particle separation theory, the force acting until the particles are separated was calculated using the Lagrangian-based computational fluid dynamics (CFD) methodology. As a result, it was proved that the centrifugal force and drag acting on the critical diameter having a separation efficiency of 50% were similar, and the particle separation phenomenon in the cyclone occurred from the critical diameter, and it was set as an important dependent variable. For developing a critical diameter prediction model based on machine learni... [more]
Theoretical Evaluation of the Melting Efficiency for the Single-Screw Micro-Extrusion Process: The Case of 3D Printing of ABS
Andrea La Gala, Rudinei Fiorio, Mustafa Erkoç, Ludwig Cardon, Dagmar R. D’hooge
June 10, 2021 (v1)
Subject: Other
Keywords: additive manufacturing, melting, micro-extrusion, polymer melting model, process design, rapid prototyping, single screw extrusion
One of the challenges for single-screw micro-extrusion or additive manufacturing (AM), thus 3D printing, of polymers is controlling the melting efficiency so that energy and equipment costs can be minimized. Here, a numerical model is presented for AM process design, selecting acrylonitrile−butadiene−styrene (ABS) as viscoelastic reference polymer. It is demonstrated that AM melting is different compared to conventional melting due to variation in extrusion dimensions, leading to a different balance in heating by conduction and viscous heat dissipation as caused by the shearing between the melt layers in the associated film layer near the barrel. The thickness of this melt film layer is variable along the screw length, and it is shown that simplified models assuming an overall average value are too approximate. It is highlighted that the screw frequency, pitch angle and compression ratio are important process parameters to control the point of melt finalization. In addition, the power-... [more]
Production of Protein Hydrolysate Containing Antioxidant and Angiotensin -I-Converting Enzyme (ACE) Inhibitory Activities from Tuna (Katsuwonus pelamis) Blood
Natthaphon Mongkonkamthorn, Yuwares Malila, Suthasinee Yarnpakdee, Sakunkhun Makkhun, Joe M. Regenstein, Sutee Wangtueai
June 10, 2021 (v1)
Subject: Biosystems
Keywords: ACE inhibitory activities, antioxidants, Katsuwonus pelamis, neutrase, protein hydrolysates, skipjack, tuna blood
Tuna blood (TB) was subjected to enzymatic hydrolysis. The effects of the relationship of hydrolysis time (30−180 min) and enzyme concentration (0.5−3.0% w/w protein) on the degree of hydrolysis (DH), yield, antioxidant and angiotensin-I-converting enzyme (ACE) inhibitory activities were determined. The response surface methodology (RSM) showed that TB hydrolysis’s optimum conditions were hydrolysis for 180 min and Alcalase, Neutrase or Flavourzyme at 2.81%, 2.89% or 2.87% w/w protein, respectively. The hydrolysates with good DH (40−46%), yield (3.5−4.6%), the IC50 of DPPH (0.8−1.6 mg/mL) and ABTS (1.0−1.4 mg/mL) radical scavenging activity, ferric reducing antioxidant power (FRAP) value (0.28−0.65 mmol FeSO4/g) and IC50 of ACE inhibitory activity (0.15−0.28 mg/mL) were obtained with those conditions. The TB hydrolysate using Neutrase (TBHN) was selected for characterization in terms of amino acid composition, peptide fractions and sensory properties. The essential, hydrophobic and hyd... [more]
Evaluation for the Removal Efficiency of VOCs and Heavy Metals by Zeolites-Based Materials in the Wastewater: A Case Study in the Tito Scalo Industrial Area
Maura Mancinelli, Antonella Arfè, Annalisa Martucci, Luisa Pasti, Tatiana Chenet, Elena Sarti, Giulia Vergine, Claudia Belviso
June 10, 2021 (v1)
Subject: Materials
Keywords: groundwater contamination, heavy metals, Tito Scalo, VOCs, ZSM-5 and 13X zeolites
The current study was designed to demonstrate the efficiency of selected zeolites in the immobilization of heavy metals and volatile organic compounds from water in the industrial area of Tito Scalo (Basilicata Region in Southern Italy). The efficiency of zeolite materials has been evaluated by analyzing real water samples, by a multi-technique approach. Gas chromatography (GC) and inductively coupled plasma optical emission spectrometry (ICP-OES) were selected for the detection of volatile organic compounds (VOCs) and heavy metals respectively, and then by thermal analysis (TG, DTA) and X-ray powder diffraction (XRD) to verify the presence of contaminants in the structural channels of the adsorbents. ZSM-5 zeolite (MFI topology) was suitable for volatile organic compounds, showing removal efficiencies 87%. 13X (FAU topology) was more selective for in situ abatements of heavy metals, with efficiencies up to 100%. After VOCs and heavy metals removal, structure refinements of loaded zeol... [more]
Numerical Investigation of the Characteristics of the In-Cylinder Air Flow in a Compression-Ignition Engine for the Application of Emulsified Biofuels
Mohd Fadzli Hamid, Mohamad Yusof Idroas, Mazlan Mohamed, Shukriwani Sa'ad, Teoh Yew Heng, Sharzali Che Mat, Muhamad Azman Miskam, Muhammad Khalil Abdullah
June 10, 2021 (v1)
Keywords: biofuel, compression-ignition (CI) engine, Computational Fluid Dynamics, emulsified biofuel, guide vanes, piston
This paper presents a numerical analysis of the application of emulsified biofuel (EB) to diesel engines. The study performs a numerical study of three different guide vane designs (GVD) that are incorporated with a shallow depth re-entrance combustion chamber (SCC) piston. The GVD variables were used in three GVD models with different vane heights, that is, 0.2, 0.4 and 0.6 times the radius of the intake runner (R) and these were named 0.20R, 0.40R and 0.60R. The SCC piston and GVD model were designed using SolidWorks 2017, while ANSYS Fluent version 15 was used to perform cold flow engine 3D analysis. The results of the numerical study showed that 0.60R is the optimum guide vane height, as the turbulence kinetic energy (TKE), swirl ratio (Rs), tumble ratio (RT) and cross tumble ratio (RCT) in the fuel injection region improved from the crank angle before the start of injection (SOI) and start of combustion (SOC). This is essential to break up the heavier-fuel molecules of EB so that... [more]
Hot Melt Extrusion Processing Parameters Optimization
Abdullah Alshetaili, Saad M. Alshahrani, Bjad K. Almutairy, Michael A. Repka
June 10, 2021 (v1)
Keywords: design of experiment, experimental trials, hot-melt extrusion, process parameters
The aim of this study was to demonstrate the impact of processing parameters of the hot-melt extrusion (HME) on the pharmaceutical formulation properties. Carbamazepine (CBZ) was selected as a model water-insoluble drug. It was incorporated into Soluplus®, which was used as the polymeric carrier, to produce a solid dispersion model system. The following HME-independent parameters were investigated at different levels: extrusion temperature, screw speed and screw configuration. Design of experiment (DOE) concept was applied to find the most significant factor with minimum numbers of experimental runs. A full two-level factorial design was applied to assess the main effects, parameter interactions and total error. The extrudates’ CBZ content and the in vitro dissolution rate were selected as response variables. Material properties, including melting point, glass transition, and thermal stability, and polymorphs changes were used to set the processing range. In addition, the extruder torq... [more]
Quantifying the Effect of COD to TN Ratio, DO Concentration and Temperature on Filamentous Microorganisms’ Population and Trans-Membrane Pressure (TMP) in Membrane Bio-Reactors (MBR)
Petros Gkotsis, Giannis Lemonidis, Manassis Mitrakas, Alexandros Pentedimos, Margaritis Kostoglou, Anastasios Zouboulis
June 10, 2021 (v1)
Keywords: filament index, filamentous bacteria, fouling control, fouling modeling, Membrane Bioreactors (MBR)
Using moderate populations of filaments in the biomass of Membrane Bio-Reactors (MBRs) is a biological anti-fouling method which has been increasingly applied over the last few years. This study aims to quantify the effect of COD to TN ratio, Dissolved Oxygen (DO) concentration and temperature on filaments’ population and Trans-Membrane Pressure (TMP) in a pilot-scale MBR, with a view to reducing membrane fouling. The novelty of the present work concerns the development of a mathematical equation that correlates fouling rate (dTMP/dt) with the population of filamentous microorganisms, assessed by the Filament Index (FI), and with the concentration of the carbohydrate fraction of Soluble Microbial Products (SMPc). Apart from TMP and SMPc, other fouling-related biomass characteristics, such as sludge filterability and settleability, were also examined. It was shown that at high COD to TN ratio (10:1), low DO concentration in the filaments’ tank (0.5 ± 0.3 mg/L) and high temperature (24−3... [more]
Nitrogen Recovery from Swine Manure Using a Zeolite-Based Process
Markus Ellersdorfer, Sandro Pesendorfer, Kristina Stocker
June 10, 2021 (v1)
Keywords: manure processing, nutrient recovery, sustainable agriculture
Intensive pig farming produces huge amounts of swine manure, which can cause regional nutrient imbalances and represent a potential source of soil and water pollution due to manure over-application. In order to improve nutrient stewardship, technologies for manure treatment and selective recovery of nutrients (especially ammonia) have to be developed to foster agriculture−food system sustainability. In the present study, a combined stripping and ion exchange process using natural zeolite (ion-exchanger-loop-stripping process) is tested for nitrogen recovery from swine manure to determine its technical feasibility in this novel field of application. Ammonium removal rates of 85 to 96% were achieved in pilot scale experiments with preprocessed manure (~500 L h−1 after mechanical filtration; input concentration: ~1.3 g NH4+ L−1). NH4+ was successfully transferred to a concentrated ammonium sulfate solution (final concentration: 66 g NH4+ L−1), with no significant transfer of other manure... [more]
Dog Rabies in Dhaka, Bangladesh, and Implications for Control
Masud M A, Md Hamidul Islam, Muhaiminul Islam Adnan, Chunyoung Oh
June 10, 2021 (v1)
Keywords: carrying capacity control, dhaka, free-roaming, mathematical model, optimal control, rabies, stray dog, vaccination, waste management
Controlling rabies among free-roaming street dogs has been a huge challenge in many parts of the world. Vaccination is a commonly used strategy to control rabies, however, sufficient vaccination coverage is very challenging when it comes to street dogs. Also, dog rabies data is scarce, making it difficult to develop proper strategies. In this study, we use a logistic growth incorporated epidemic model to understand the prevalence of rabies in the dog population of Dhaka, Bangladesh. The study shows that, the basic reproduction number for dog rabies in Dhaka lies between 1.1 to 1.249 and the environmental carrying capacity lies approximately between 58,110 to 194,739. Considering the vaccination and neuter programs administered in the last decade, we attempt to explain rabies transmission among dogs in this population. We found that the high basic reproduction number is associated with high environmental carrying capacity and vice versa. Further, we compare different type of control str... [more]
Analysis of Flow and Wear Characteristics of Solid−Liquid Two-Phase Flow in Rotating Flow Channel
Peng Wang, Xinyu Zhu, Yi Li
June 10, 2021 (v1)
Keywords: CFD–DPM, large particles, rotating disc, solid–liquid two-phase flow, wear
To study the flow characteristics and the wear distribution of pumps at different rotation speeds, a rotating disc with three blades was designed for experiments. Numerical simulations were conducted using a computational fluid dynamics-discrete phase model (CFD−DPM) approach. The experimental and numerical results were compared, and the flow characteristics and wear behaviors were determined. As the speed increased, the particles at the blade working surface aggregated. The particle velocity gradually increased at the outlet of the channel. The severe wear areas were all located in the outlet area of the blade working surface, and the wear area extended toward the inlet area of the blade with increasing speed. The wear rate of the blade surface increased as the speed increased, and an area with a steady wear rate appeared at the outlet area of the blade. When the concentration was more than 8%, the severe wear areas were unchanged at the same speed. When the speed increased, the sever... [more]
Digital Twinning Process for Stirred Tank Reactors/Separation Unit Operations through Tandem Experimental/Computational Fluid Dynamics (CFD) Simulations
Blaž Oblak, Simon Babnik, Vivian Erklavec-Zajec, Blaž Likozar, Andrej Pohar
June 10, 2021 (v1)
Keywords: Computational Fluid Dynamics, dissolution modelling, mixing simulation, reactor design
Computational fluid dynamics simulations (CFD) were used to evaluate mixing in baffled and unbaffled vessels. The Reynolds-averaged Navier−Stokes k−ε model was implemented in OpenFOAM for obtaining the fluid flow field. The 95% homogenization times were determined by tracer tests. Experimental tests were conducted by injecting sodium chloride into the vessel and measuring the conductivity with two conductivity probes, while the simulations replicated the experimental conditions with the calculation of the transport of species. It was found that the geometry of the system had a great effect on the mixing time, since the irregular flow distribution, which can be obtained with baffles, can lead to local stagnation zones, which will increase the time needed to achieve the homogenization of the solute. It was also found that measuring local, pointwise concentrations can lead to a high underestimation of the global mixing time required for the homogenization of the entire vessel. Dissolution... [more]
Application of a Modeling Tool to Describe Fly Ash Generation, Composition, and Melting Behavior in a Wheat Straw Fired Commercial Power Plant
Ibai Funcia, Fernando Bimbela, Javier Gil, Luis M. Gandía
June 10, 2021 (v1)
Keywords: biomass combustion, boiler, fly ash, thermochemical modeling, vibrating grate
Ash behavior is a key operational aspect of industrial-scale power generation by means of biomass combustion. In this work, FactSageTM 6.4 software was used to develop and assess three models of wheat straw combustion in a vibrating grate-fired commercial boiler of 16 MWth, aiming to describe the inorganic elements release as well as fly ash melting behavior and composition. Simulations were carried out solving four consecutive calculation stages corresponding to the main plant sections. Chemical fractionation was adopted in order to distinguish between reactive, inert and partially reactive biomass fractions. The developed models allow take into account different levels of partial reactivity, values of the temperature for each sub-stage on the grate, and ways to apply entrained streams based on data from the elemental analyses of the fly ashes. To this end, two one-week experimental campaigns were conducted in the plant to carry out the sampling. It has been found that considering che... [more]
A Thermal Design of a 1 kW-Class Shell and Tube Methanol Steam Reforming System with Internal Evaporator
Dongjin Yu, Ngoc Trinh Van, Jinwon Yun, Sangseok Yu
June 10, 2021 (v1)
Keywords: Hydrogen, methanol steam reformer, reforming rate, shell-and-tube, thermal efficiency
Due to its low operating temperature, the performance of a methanol steam reformer depends on efficient thermal integration. In particular, the integration of the evaporator is crucial to enhance thermal efficiency. This paper presents two different configurations to utilize thermal energy for evaporation of methanol/water mixture. The reformer system is composed of a methanol steam reformer, a burner, and two different evaporators such as internal evaporator and external evaporator. Moreover, since the performance of the reforming system strongly depends on thermal utilization, a heat recovery module is designed for methanol reforming system with internal evaporator. The heat duty and steam to carbon ratio (S/C) are the variables for evaluation of its suitability. The experimental results indicate that the internal evaporator with the auxiliary heat recovery module provides stable conditions over wide operating ranges.
Mathematical Modeling of the Production of Elastomers by Emulsion Polymerization in Trains of Continuous Reactors
Enrique Saldívar-Guerra, Ramiro Infante-Martínez, José María Islas-Manzur
June 10, 2021 (v1)
Keywords: emulsion polymerization, mathematical modeling, nitrile rubber, styrene–butadiene rubber
A mechanistic model is proposed to describe the emulsion polymerization processes for the production of styrene−butadiene rubber (SBR) and acrylonitrile−butadiene rubber (NBR) elastomers in trains of continuous stirred tank reactors (CSTRs). A single model was used to describe both processes by choosing the proper physicochemical parameters of each system. Most of these parameters were taken from literature sources or estimated a priori; only one parameter (the entry rate coefficient) was used as an adjustable value to reproduce the kinetics (mainly conversion), and another parameter (the transfer to polymer rate coefficient) was used to fit the molecular weight distribution (MWD) experimental values from plant data. A 0-1-2 model for the number of particles and for the moments of the MWD was used to represent with more fidelity the compartmentalization effects. The model was based on approaches used in previous emulsion polymerization models published in the literature, with the premi... [more]
The Effect of Root Clearance on Mechanical Energy Dissipation for Axial Flow Pump Device Based on Entropy Production
Yanjun Li, Yunhao Zheng, Fan Meng, Majeed Koranteng Osman
June 10, 2021 (v1)
Keywords: axial-flow pump, Computational Fluid Dynamics, energy dissipation, entropy production, root clearance radius
The axial flow pump is a low head, high discharge pump usually applicable in drainage and irrigation facilities. A certain gap should be reserved between the impeller blade root and the impeller hub to ensure the blade adjustability to broaden the high-efficiency area. The pressure difference between its blade surface induces leakage flow in the root clearance region, which decreases hydraulic performance and operational stability. Therefore, this study was carried out to investigate the effect of root clearance on mechanical energy dissipation using numerical simulation and entropy production methods. The numerical model was validated with an external characteristics test, and unsteady flow simulations were conducted on the axial flow pump under four different root clearance radii. The maximum reductions of 15.5% and 6.8% for head and hydraulic efficiency are obtained for the largest root clearance of 8 mm, respectively. The dissipation based on entropy theory consists of indirect dis... [more]
Impact of Process Parameters and Bulk Properties on Quality of Dried Hops
Sharvari Raut, Gardis J. E. von Gersdorff, Jakob Münsterer, Klaus Kammhuber, Oliver Hensel, Barbara Sturm
June 10, 2021 (v1)
Keywords: bulk weight, chemical analysis, energy consumption, hop cones size distribution
Hops are critical to the brewing industry. In commercial hop drying, a large bulk of hops is dried in multistage kilns for several hours. This affects the drying behavior and alters the amount and chemical composition of the hop oils. To understand these changes, hops of the var. Hallertauer Tradition were dried in bulks of 15, 25 and 35 kg/m² at 60 °C and 0.35 m/s. Additionally, bulks of 25 kg/m² were also dried at 65 °C and 0.45 m/s to assess the effect of change in temperature and velocity, respectively. The results obtained show that bulk weights significantly influence the drying behavior. Classification based on the cone size reveals 45.4% medium cones, 41.2% small cones and 8.6% large cones. The highest ΔE value of 6.3 and specific energy consumption (113,476 kJ/kgH2O) were observed for the 15 kg/m² bulk. Increasing the temperature from 60 °C to 65 °C increased the oil yield losses by about 7% and myrcene losses by 22%. The results obtained show that it is important to define an... [more]
An Agricultural Products Supply Chain Management to Optimize Resources and Carbon Emission Considering Variable Production Rate: Case of Nonperishable Corps
Mohammed Alkahtani, Muhammad Omair, Qazi Salman Khalid, Ghulam Hussain, Biswajit Sarkar
June 10, 2021 (v1)
Keywords: agri-supply chain management, eco-efficient production, imperfect production, optimal resources, variable production rate
The management of the man−machine interaction is essential to achieve a competitive advantage among production firms and is more highlighted in the processing of agricultural products. The agricultural industry is underdeveloped and requires a transformation in technology. Advances in processing agricultural products (agri-product) are essential to achieve a smart production rate with good quality and to control waste. This research deals with modelling of a controllable production rate by a combination of the workforce and machines to minimize the total cost of production. The optimization of the carbon emission variable and management of the imperfection in processing makes the model eco-efficient. The perishability factor in the model is ignored due to the selection of a single sugar processing firm in the supply chain with a single vendor for the pragmatic application of the proposed research. A non-linear production model is developed to provide an economic benefit to the firms in... [more]
Fractionation and Characterization of Petroleum Asphaltene: Focus on Metalopetroleomics
Fang Zheng, Quan Shi, Germain Salvato Vallverdu, Pierre Giusti, Brice Bouyssiere
June 10, 2021 (v1)
Subject: Materials
Keywords: aggregation, analytical techniques, asphaltene, fractionation methods, heteroatoms, metals
Asphaltenes, as the heaviest and most polar fraction of petroleum, have been characterized by various analytical techniques. A variety of fractionation methods have been carried out to separate asphaltenes into multiple subfractions for further investigation, and some of them have important reference significance. The goal of the current review article is to offer insight into the multitudinous analytical techniques and fractionation methods of asphaltene analysis, following an introduction with regard to the morphologies of metals and heteroatoms in asphaltenes, as well their functions on asphaltene aggregation. Learned lessons and suggestions on possible future work conclude the present review article.
Preparation of Hybrid Polyaniline/Nanoparticle Membranes for Water Treatment Using an Inverse Emulsion Polymerization Technique under Sonication
Itamar Chajanovsky, Ran Y. Suckeveriene
June 10, 2021 (v1)
Subject: Materials
Keywords: anti-biofouling, carbon nanotubes, inverse emulsion polymerization, membrane permeability, polyaniline
This manuscript describes a novel in situ interfacial dynamic inverse emulsion polymerization process under sonication of aniline in the presence of carbon nanotubes (CNT) and graphene nanoparticles in ethanol. This polymerization method is simple and very rapid (up to 10 min) compared to other techniques reported in the literature. During polymerization, the nanoparticles are coated with polyaniline (PANI), forming a core-shell structure, as confirmed by high-resolution scanning electron microscopy (HRSEM) and Fourier-Transform Infrared (FTIR) measurements. The membrane pore sizes range between 100−200 nm, with an average value of ~119 ± 28.3 nm. The film resistivity decreased when treated with alcohol, and this behavior was used for selection of the most efficient alcohol as a solvent for this polymerization technique. The membrane permeability of the PANI grafted CNT was lower than the CNT reference, thus demonstrating better membranal properties. As measured by water permeability,... [more]
Catalytic Performance of Lanthanum Promoted Ni/ZrO2 for Carbon Dioxide Reforming of Methane
Mahmud S. Lanre, Ahmed S. Al-Fatesh, Anis H. Fakeeha, Samsudeen O. Kasim, Ahmed A. Ibrahim, Abdulrahman S. Al-Awadi, Attiyah A. Al-Zahrani, Ahmed E. Abasaeed
June 10, 2021 (v1)
Keywords: catalyst stability, lanthanum promoters, methane dry reforming, nickel catalyst, zirconium oxide
Nickel catalysts supported on zirconium oxide and modified by various amounts of lanthanum with 10, 15, and 20 wt.% were synthesized for CO2 reforming of methane. The effect of La2O3 as a promoter on the stability of the catalyst, the amount of carbon formed, and the ratio of H2 to CO were investigated. In this study, we observed that promoting the catalyst with La2O3 enhanced catalyst activities. The conversions of the feed, i.e., methane and carbon dioxide, were in the order 10La2O3 > 15La2O3 > 20La2O3 > 0La2O3, with the highest conversions being about 60% and 70% for both CH4 and CO2 respectively. Brunauer−Emmett−Teller (BET) analysis showed that the surface area of the catalysts decreased slightly with increasing La2O3 doping. We observed that 10% La2O3 doping had the highest specific surface area (21.6 m2/g) and the least for the un-promoted sample. The higher surface areas of the promoted samples relative to the reference catalyst is an indication of the concentration of the meta... [more]
The Carbon-Coated ZnCo2O4 Nanowire Arrays Pyrolyzed from PVA for Enhancing Lithium Storage Capacity
Wenjia Zhao, Zhaoping Shi, Yongbing Qi, Jipeng Cheng
June 10, 2021 (v1)
Subject: Materials
Keywords: carbon coating, lithium-ion batteries, nanoarray composites, polyvinyl alcohol
In this paper, ZnCo2O4 nanowire arrays with a uniform carbon coating were introduced when polyvinyl alcohol (PVA) served as the carbon source. The coating process was completed by a facile bath method in PVA aqueous solution and subsequent pyrolyzation. The PVA-derived carbon-coated ZnCo2O4 nanowire array composites can be used directly as the binder-free and self-supported anode materials for lithium-ion batteries. In the carbon-coated ZnCo2O4 composites, the carbon layer carbonized from PVA can accelerate the electron transfer and accommodate the volume swing during the cycling process. The lithium storage properties of the carbon-coated ZnCo2O4 composites are investigated. It is believed that the novel carbon-coating method is universal and can be applied to other nanoarray materials.
Stability of Plasma Protein Composition in Dried Blood Spot during Storage
Kristina A. Malsagova, Alexander A. Stepanov, Arthur T. Kopylov, Dmitry V. Enikeev, Natalia V. Potoldykova, Alexander A. Izotov, Tatyana V. Butkova, Anna L. Kaysheva
June 10, 2021 (v1)
Subject: Biosystems
Keywords: DBS, dried blood spot, mass spectrometry, membrane carrier, plasma, sample storage
Dried blood spot (DBS) technology has become a promising utility for the transportation and storage of biological fluids aimed for the subsequent clinical analysis. The basis of the DBS method is the adsorption of the components of a biological sample onto the surface of a membrane carrier, followed by drying. After drying, the molecular components of the biosample (nucleic acids, proteins, and metabolites) can be analyzed using modern omics, immunological, or genomic methods. In this work, we investigated the safety of proteins on a membrane carrier by tryptic components over time and at different temperatures (+4, 0, 25 °C) and storage (0, 7, 14, and 35 days). It was shown that the choice of a protocol for preliminary sample preparation for subsequent analytical molecular measurements affects the quality of the experimental results. The protocol for preliminary preparation of a biosample directly in a membrane carrier is preferable compared to the protocol with an additional stage of... [more]
Influence of Gasoline Addition on Biodiesel Combustion in a Compression-Ignition Engine with Constant Settings
Wojciech Tutak, Arkadiusz Jamrozik
June 10, 2021 (v1)
Keywords: biodiesel, combustion, dual fuel, Gasoline, ignition delay
This paper presents results of investigation of co-combustion process of biodiesel with gasoline, in form of mixture and using dual fuel technology. The main objective of this work was to show differences in both combustion systems of the engine powered by fuels of different reactivity. This paper presents parameters of the engine and the assessment of combustion stability. It turns out that combustion process of biodiesel was characterized by lower ignition delay compared to diesel fuel combustion. For 0.54 of gasoline energetic fraction, the ignition delay increased by 25% compared to the combustion of the pure biodiesel, but for dual fuel technology for 0.95 of gasoline fraction it was decreased by 85%. For dual fuel technology with the increase in gasoline fraction, the specific fuel consumption (SFC) was decreased for all analyzed fractions of gasoline. In the case of blend combustion, the SFC was increased in comparison to dual fuel technology. An analysis of spread of ignition d... [more]
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