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Records added in 2019
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Showing records 1 to 25 of 1602. [First] Page: 1 2 3 4 5 Last
Assessment of the Toxicity of Natural Oils from Mentha piperita, Pinus roxburghii, and Rosa spp. Against Three Stored Product Insects
Marwa I. Mackled, Mervat EL-Hefny, May Bin-Jumah, Trandil F. Wahba, Ahmed A. Allam
December 16, 2019 (v1)
Subject: Biosystems
Keywords: bioassay, contact film, fumigation, GC-MS analysis, Mentha piperita, natural plant oils, Pinus roxburghii, Rosa spp., stored product insects
Three natural oils extracted from Mentha piperita, Pinus roxburghii, and Rosa spp. were assessed in order to determine their insecticidal activity against the adults of three stored product insects: the rice weevil (Sitophilus oryzae L.), the lesser grain borer (Rhyzopertha dominica, Fabricius), and the red flour beetle (Tribolium castaneum, Herbst.). By Gas chromatography−mass spectrometry (GC/MS) analysis, the main compounds in the n-hexane oil from Rosa spp. were determined to be methyl eugenol (52.17%), phenylethyl alcohol (29.92%), diphenyl ether (7.75%), and geraniol (5.72%); in the essential oil from M. piperita, they were menthone (20.18%), 1,8-cineole (15.48%), menthyl acetate (13.13%), caryophyllene (4.82%), β-pinene (4.37%), and D-limonene (2.81%); and from the foliage of P. roxburghii, they were longifolene (19.52%), caryophyllene (9.45%), Δ-3-carene (7.01%), α-terpineol (6.75%), and γ-elemene (3.88%). S. oryzae and R. dominica were reared using sterilized wheat grains, and... [more]
Green Synthesized Silver Nanoparticles of Myrtus communis L (AgMC) Extract Inhibits Cancer Hallmarks via Targeting Aldose Reductase (AR) and Associated Signaling Network
Abdulwahab Ali Abuderman, Rabbani Syed, Abdullah A. Alyousef, Mohammed S. Alqahtani, Mohammad Shamsul Ola, Abdul Malik
December 16, 2019 (v1)
Subject: Biosystems
Keywords: anti-cancer, green synthesis, Myrtus communis L., silver NPs
In this current study, we demonstrated the green synthesis and characterization of silver nanoparticles using Myrtus communis L. plant extract (Ag-MC) and its evaluation of anticancer and antimicrobial activities. The green synthesis of (Ag-MC), was assessed by numerous characterization techniques such as ultraviolet-visible spectroscopy (UV-VIS), Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD) transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy (EDX). The anti-cancer activity of the green synthesized silver nanoparticles was evaluated by the median inhibitory dose (IC50) on human liver carcinoma cell lines (HepG2). These results suggested that SN-NPs can be used as effective anticancer cell lines, as well as antibacterial and antiseptic agents in the medical field. This study showed that overexpression of aldose reductase (AR) in the human liver carcinoma cell line, HepG2, was down regulated by administration of SN-MC. The do... [more]
Interaction of Wu’s Slip Features in Bioconvection of Eyring Powell Nanoparticles with Activation Energy
Anas M. Alwatban, Sami Ullah Khan, Hassan Waqas, Iskander Tlili
December 16, 2019 (v1)
Keywords: activation energy, eyring powell nanofluid, motile microorganisms, shooting technique, Wu’s slip
The current continuation aim is to explore the rheological consequences of Eyring Powell nanofluid over a moving surface in the presence of activation energy and thermal radiation. The bioconvection of magnetized nanoparticles is executed with the evaluation of motile microorganism. The most interesting Wu’s slip effects are also assumed near the surface. The evaluation of nanoparticles for current flow problems has been examined by using Buongiorno’s model. The governing equations for the assumed flow problem are constituted under the boundary layer assumptions. After converting these equations in dimensionless form, the famous shooting technique is executed. A detailed physical significance is searched out in the presence of slip features. The variation of physical quantities, namely velocity, nanoparticles temperature, nano particles concentration, motile microorganism density, skin friction coefficient, local Nusselt number and motile organism density number are observed with detai... [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]
Non-Structural Damage Verification of the High Pressure Pump Assembly Ball Valve in the Gasoline Direct Injection Vehicle System
Liang Lu, Qilong Xue, Manyi Zhang, Liangliang Liu, Zhongyu Wu
December 16, 2019 (v1)
Keywords: Finite element simulation, high pressure ball valve, Static and fatigue analysis, Static friction contact
The injection pressure of the gasoline direct injection vehicle is currently developing from the low pressure to the high pressure, and the increase of the injection pressure has brought various damage problems to the high pressure pump structure. These problems should be solved urgently. In this paper, the damage problem of the high pressure pump unloading valve ball in a gasoline direct injection vehicle under high pressure conditions is studied. The theoretical calculation of the force of the pressure relief valve is carried out. Firstly, the equivalent friction coefficient is obtained by decoupling analysis of the statically indeterminate model. Based on this, a finite element model is established. The equivalent stress is obtained by numerical simulation. The equivalent stress is compared with the yield strength of the valve ball material to determine that the valve ball damage is a non-static damage. At the same time, the s-N curve of the probability of destruction of one-million... [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]
Optimization of Baicalin, Wogonoside, and Chlorogenic Acid Water Extraction Process from the Roots of Scutellariae Radix and Lonicerae japonicae Flos Using Response Surface Methodology (RSM)
Jichang Li, Rui Wang, Zunlai Sheng, Zhiyong Wu, Chunli Chen, Muhammad Ishfaq
December 16, 2019 (v1)
Keywords: baicalin, chlorogenic acid, extraction process, HPLC, wogonoside
In this study, a simultaneous water extraction process for baicalin, wogonoside, and chlorogenic acid has been optimized. The effect of extraction temperature, extraction time, and liquid−solid ratio was scrutinized by single factor experiments and further analyzed by Box−Behnken design (BBD) approach using response surface methodology (RSM). The extraction yield of investigated compounds was determined by high performance liquid chromatography (HPLC). Single-factor experiments and response surface analysis results revealed that the optimized conditions are: Liquid to solid ratio 25:1 (mL/g), extraction temperature 93 °C, extraction time 2.4 h, and the extraction cycle two. Importantly, it has been noted that under the above conditions, concentrations of baicalin, wogonoside, and chlorogenic were 0.078, 0.031, and 0.013 mg/mL, respectively, and the overall desirability (OD) value was 0.76 which was higher than the non-optimized conditions and the deviation from the predicted OD value w... [more]
Valorization of Industrial Vegetable Waste Using Dilute HCl Pretreatment
Donald Blue, Dhan Lord Fortela, William Holmes, David LaCour, Shayla LeBoeuf, Cody Stelly, Ramalingam Subramaniam, Rafael Hernandez, Mark E. Zappi, Emmanuel D. Revellame
December 16, 2019 (v1)
Keywords: furans, lignocellulosic biomass, microbial inhibitors, onion wastes, organic acids
A solid vegetable waste stream was subjected to dilute acid (HCl) pretreatment with the goal of converting the waste into a form that is amenable to biochemical processes which could include microbial lipids, biohydrogen, and volatile organic acids production. Specifically, this study was conducted to identify the most suitable pretreatment condition that maximizes the yield or concentration of sugars while minimizing the production of compounds which are inhibitory to microbes (i.e., furfural, hydroxymethylfurfural, and organic acids). Temperatures from 50−150 °C and HCl loading from 0−7 wt % were studied to using an orthogonal central composite response surface design with eight center points. The effects of the variables under study on the resulting concentrations of sugars, organic acids, and furans were determined using the quadratic response surface model. Results indicated that the biomass used in this study contains about 5.7 wt % cellulose and 83.8 wt % hemicellulose/pectin. W... [more]
Thermo-Diffusion and Multi-Slip Effect on an Axisymmetric Casson Flow over a Unsteady Radially Stretching Sheet in the Presence of Chemical Reaction
Faraz Faraz, Syed Muhammad Imran, Bagh Ali, Sajjad Haider
December 16, 2019 (v1)
Keywords: axisymmetric flow, casson fluid, Keller-Box technique, multi-slip, thermo-diffusion
The objective of this article is to investigate the impacts of thermo-diffusion effect on unsteady axisymmetric Casson flow over a time-dependent radially stretching sheet with a multi-slip parameter and the force of chemical reaction. We employed an established similarity transformation to this non-linear partial differential system to convert it into a system of ordinary differential equations. The numerical results are attained for this system by using KELLER-BOX implicit finite difference scheme. It has great reliability and accuracy even a very short time period for computational simulation. The impacts of influential flow parameters on fluid flow are sketched through graphs and the numerical results are thoroughly argued. The temperature, velocity and wall concentration control parameters are analyzed. (i) It is witnessed that chemical reaction is not favorable to enhance the velocity profile. (ii) Multi-slip parameters vary inversely with velocity profile. (iii) The fluid concen... [more]
Structural Influence and Interactive Binding Behavior of Dopamine and Norepinephrine on the Greek-Key-Like Core of α-Synuclein Protofibril Revealed by Molecular Dynamics Simulations
Yu Zou, Zhiwei Liu, Zhiqiang Zhu, Zhenyu Qian
December 16, 2019 (v1)
Keywords: amyloid protofibril, inhibitory mechanism, molecular dynamics simulation, protein–ligand interaction, small molecules
The pathogenesis of Parkinson’s disease (PD) is closely associated with the aggregation of α-synuclein (αS) protein. Finding the effective inhibitors of αS aggregation has been considered as the primary therapeutic strategy for PD. Recent studies reported that two neurotransmitters, dopamine (DA) and norepinephrine (NE), can effectively inhibit αS aggregation and disrupt the preformed αS fibrils. However, the atomistic details of αS-DA/NE interaction remain unclear. Here, using molecular dynamics simulations, we investigated the binding behavior of DA/NE molecules and their structural influence on αS44−96 (Greek-key-like core of full length αS) protofibrillar tetramer. Our results showed that DA/NE molecules destabilize αS protofibrillar tetramer by disrupting the β-sheet structure and destroying the intra- and inter-peptide E46−K80 salt bridges, and they can also destroy the inter-chain backbone hydrogen bonds. Three binding sites were identified for both DA and NE molecules interacti... [more]
Evaluation of Municipal Solid Wastes Based Energy Potential in Urban Pakistan
Muhammad Mobin Siddiqi, Muhammad Nihal Naseer, Yasmin Abdul Wahab, Nor Aliya Hamizi, Irfan Anjum Badruddin, Zaira Zaman Chowdhury, Omid Akbarzadeh, Mohd Rafie Johan, T. M. Yunus Khan, Sarfaraz Kamangar
December 16, 2019 (v1)
Subject: Energy Policy
Keywords: alternative solid fuel, energy generation, incineration, municipal solid waste management, solid waste to energy, waste management
Solid waste management needs re-evaluating in developing countries like Pakistan, which currently employs landfilling as a first option. Over time, increasing population will result in decreasing space for landfill sites, ultimately increasing the cost of landfilling, while increasing accumulated waste will cause pollution. Locating and preparing a sanitary landfill includes the securing of large sectors and also everyday activity with the end goal to limit potential negative impacts. Energy production from municipal solid waste (MSW) is a perceptive idea for large cities, such as Karachi, as waste, which is an undesirable output that adds to land and air pollution, is transformed into a vital source of energy. The current study strives to provide a destination to solid waste by evaluating the energy potential that waste provides for power generation by the process of incineration. A sustainable energy generation plant based on the Rankine cycle is proposed. This study evaluates the va... [more]
Techno-Economic Implications of Fed-Batch Enzymatic Hydrolysis
Ellen Argo, Deepak R. Keshwani
December 16, 2019 (v1)
Keywords: cellulosic ethanol, fed-batch hydrolysis, process simulation, Technoeconomic Analysis
Fed-batch enzymatic hydrolysis has the potential to improve the overall process of converting cellulosic biomass into ethanol. This paper utilizes a process simulation approach to identify and quantify techno-economic differences between batch and fed-batch enzymatic hydrolysis in cellulosic ethanol production. The entire process of converting corn stover into ethanol was simulated using SuperPro Designer simulation software. The analysis was conducted for a plant capacity of 2000 metric tons of dry biomass per day. A literature review was used to identify baseline parameters for the process. The sensitivity of the ethanol production cost to changes in sugar conversion efficiency, plant capacity, biomass cost, power cost, labor cost, and enzyme cost was evaluated using the process simulation. For the base scenario, the ethanol unit production cost was approximately $0.10/gallon lower for fed-batch hydrolysis. The greatest differences were seen in facilities costs, labor costs, and capi... [more]
Theoretical Analysis of Forced Segmented Temperature Gradients in Liquid Chromatography
Adnan Hayat, Xinghai An, Shamsul Qamar, Gerald Warnecke, Andreas Seidel-Morgenstern
December 16, 2019 (v1)
Keywords: cycle time, equilibrium model, external heating or cooling source, liquid chromatography, method of characteristics, periodic injection, production rate, temperature gradients
An equilibrium model is applied to study the effect of forced temperature gradients introduced through heat exchange via specific segments of the wall of a chromatographic column operating with a liquid mobile phase. For illustration of the principle, the column is divided into two segments in such a manner that the first segment is kept at a fixed reference temperature, while the temperature of the second segment can be changed stepwise through fixed heating or cooling over the column wall to modulate the migration speeds of the solute concentration profiles. The method of characteristics is used to obtain the solution trajectories analytically. It is demonstrated that appropriate heating or cooling in the second segment can accelerate or decelerate the specific concentration profiles in order to improve certain performance criteria. The results obtained verify that the proposed analysis is well suited to evaluate the application of forced segmented temperature gradients. The suggeste... [more]
Novel Parallel Heterogeneous Meta-Heuristic and Its Communication Strategies for the Prediction of Wind Power
Jeng-Shyang Pan, Pei Hu, Shu-Chuan Chu
December 16, 2019 (v1)
Keywords: communication strategies, dynamic change, heterogeneous, neural network, parallel, prediction, wind power
Wind and other renewable energy protects the ecological environment and improves economic efficiency. However, it is difficult to accurately predict wind power because of the randomness and volatility of wind. This paper proposes a new parallel heterogeneous model to predict the wind power. Parallel meta-heuristic saves computation time and improves solution quality. Four communication strategies, which include ranking, combination, dynamic change and hybrid, are introduced to balance exploration and exploitation. The dynamic change strategy is to dynamically increase or decrease the members of subgroup to keep the diversity of the population. The benchmark functions show that the algorithms have excellent performance in exploration and exploitation. In the end, they are applied to successfully realize the prediction for wind power by training the parameters of the neural network.
Effects of Processing Conditions on the Simultaneous Extraction and Distribution of Oil and Protein from Almond Flour
Neiva M. de Almeida, Fernanda F. G. Dias, Maria I. Rodrigues, Juliana M. L. N. de Moura Bell
December 16, 2019 (v1)
Keywords: almond flour, enzyme-assisted aqueous extraction process, oil extraction, protein extraction, solubility
The enzyme-assisted aqueous extraction process (EAEP) is an environmentally friendly strategy that simultaneously extracts oil and protein from several food matrices. The aim of this study was to investigate the effects of pH (6.5−9.5), temperature (45−55 °C), solids-to-liquid ratio (SLR) (1:12−1:8), and amount of enzyme (0.5−1.0%) on the extraction and separation of oil and protein from almond flour using a fractional factorial design. Oil and protein extraction yields from 61 to 75% and 64 to 79% were achieved, respectively. Experimental conditions resulting in higher extractability were subsequently replicated for validation of the observed effects. Oil and protein extraction yields of 75 and 72% were achieved under optimized extraction conditions (pH 9.0, 50 °C, 1:10 SLR, 0.5% (w/w) of enzyme, 60 min). Although the use of enzyme during the extraction did not lead to significant increase in extraction yields, it did impact the extracted protein functionality. The use of enzyme and a... [more]
Wind Power Short-Term Forecasting Hybrid Model Based on CEEMD-SE Method
Keke Wang, Dongxiao Niu, Lijie Sun, Hao Zhen, Jian Liu, Gejirifu De, Xiaomin Xu
December 16, 2019 (v1)
Keywords: complementary ensemble empirical mode decomposition, hybrid forecasting model, improved extreme learning machine with kernel, sample entropy, wind power forecasting
Accurately predicting wind power is crucial for the large-scale grid-connected of wind power and the increase of wind power absorption proportion. To improve the forecasting accuracy of wind power, a hybrid forecasting model using data preprocessing strategy and improved extreme learning machine with kernel (KELM) is proposed, which mainly includes the following stages. Firstly, the Pearson correlation coefficient is calculated to determine the correlation degree between multiple factors of wind power to reduce data redundancy. Then, the complementary ensemble empirical mode decomposition (CEEMD) method is adopted to decompose the wind power time series to decrease the non-stationarity, the sample entropy (SE) theory is used to classify and reconstruct the subsequences to reduce the complexity of computation. Finally, the KELM optimized by harmony search (HS) algorithm is utilized to forecast each subsequence, and after integration processing, the forecasting results are obtained. The... [more]
New Aspects on the Modeling of Dithiolactone-Mediated Radical Polymerization of Vinyl Monomers
Anete Joceline Benitez-Carreón, Jesús Guillermo Soriano-Moro, Eduardo Vivaldo-Lima, Ramiro Guerrero-Santos, Alexander Penlidis
December 16, 2019 (v1)
Keywords: dithiolactones, kinetic modeling, methyl methacrylate, RAFT polymerization, vinyl monomers
A kinetic model for the dithiolactone-mediated radical polymerization of vinyl monomers based on the persistent radical effect and reversible addition (negligible fragmentation) was used to calculate the polymerization rate and describe molar mass development in the polymerization of methyl methacrylate at 60 °C, using 2,2-azobisisobutyronitrile (AIBN) as an initiator, as well as dihydro-5-phenyl-2(3H)-thiophenethione (DTL1) and dihydro-2(3H)-thiophenethione (DTL2) as controllers. The model was implemented in the PREDICI commercial software. A good agreement between experimental data and model predictions was obtained.
Inhibition of Key Enzymes Linked to Obesity and Cytotoxic Activities of Whole Plant Extracts of Vernonia mesplilfolia Less
Jeremiah Oshiomame Unuofin, Gloria Aderonke Otunola, Anthony Jide Afolayan
December 16, 2019 (v1)
Subject: Biosystems
Keywords: HeLa, Hoechst 33342/PI staining, lipase, Vernonia mespilifolia, α-amylase, α-glucosidase
The whole plant of Vernonia mespilifolia is widely used as a traditional remedy for obesity in South Africa. The aim of this study was to investigate the anti-obesity and cytotoxic effects of Vernonia mespilifolia extracts in vitro. The α-amylase, α-glucosidase, and lipase inhibitory activities of aqueous and ethanol extracts of Vernonia mespilifolia were investigated, while the cytotoxic effects of these extracts were analyzed using Hoechst 33342 and propidium iodide (PI) dual staining on a human cervical HeLa cell line. The results showed that the LC50 (the concentration of a material will kill 50% of test organisms) values of aqueous and ethanol extracts of Vernonia mespilifolia were >200 and 149 µg/mL, respectively, to HeLa cells. Additionally, the ethanol extract exhibited the strongest inhibitory effect on the pancreatic lipase (Half-maximal inhibitory concentration (IC50) = 331.16 µg/mL) and on α-amylase (IC50 = 781.72 µg/mL), while the aqueous extract has the strongest α-glucos... [more]
Modern Modeling Paradigms Using Generalized Disjunctive Programming
Qi Chen, Ignacio Grossmann
December 16, 2019 (v1)
Subject: Optimization
Keywords: generalized disjunctive programming, mathematical programming, MINLP, process design, process modeling
Models involving decision variables in both discrete and continuous domain spaces are prevalent in process design. Generalized Disjunctive Programming (GDP) has emerged as a modeling framework to explicitly represent the relationship between algebraic descriptions and the logical structure of a design problem. However, fewer formulation examples exist for GDP compared to the traditional Mixed-Integer Nonlinear Programming (MINLP) modeling approach. In this paper, we propose the use of GDP as a modeling tool to organize model variants that arise due to characterization of different sections of an end-to-end process at different detail levels. We present an illustrative case study to demonstrate GDP usage for the generation of model variants catered to process synthesis integrated with purchasing and sales decisions in a techno-economic analysis. We also show how this GDP model can be used as part of a hierarchical decomposition scheme. These examples demonstrate how GDP can serve as a u... [more]
Symmetry Detection for Quadratic Optimization Using Binary Layered Graphs
Georgia Kouyialis, Xiaoyu Wang, Ruth Misener
December 16, 2019 (v1)
Subject: Optimization
Keywords: quadratic optimization, quadratically-constrained quadratic optimization, symmetry
Symmetry in mathematical optimization may create multiple, equivalent solutions. In nonconvex optimization, symmetry can negatively affect algorithm performance, e.g., of branch-and-bound when symmetry induces many equivalent branches. This paper develops detection methods for symmetry groups in quadratically-constrained quadratic optimization problems. Representing the optimization problem with adjacency matrices, we use graph theory to transform the adjacency matrices into binary layered graphs. We enter the binary layered graphs into the software package nauty that generates important symmetric properties of the original problem. Symmetry pattern knowledge motivates a discretization pattern that we use to reduce computation time for an approximation of the point packing problem. This paper highlights the importance of detecting and classifying symmetry and shows that knowledge of this symmetry enables quick approximation of a highly symmetric optimization problem.
A Mechanistic Model of Mass Transfer in the Extraction of Bioactive Compounds from Intact Sorghum Pericarp
Devi Yuni Susanti, Wahyudi Budi Sediawan, Mohammad Fahrurrozi, Muslikhin Hidayat
December 16, 2019 (v1)
Keywords: bioactive, Extraction, mass transfer, mechanistic, model, pericarp, process, sorghum
The extraction of phytochemical compounds from intact red sorghum grains was developed as an alternative process for producing bioactive material in the pharmaceutical industry. A mechanistic model is needed to better understand the process and enable predictive simulations for designing commercial-scale extraction systems. This paper presents a mathematical model for predicting phytochemical concentrations in the solvent and inside the pericarp of the grain at different positions during the extraction. The model is based on the mass transfer mechanism from inside the pericarp to its solid surface by diffusion, and then from the surface to a solvent during the extraction of bioactive compounds. It was numerically solved while using finite-difference approximation. The parameters considered were effective diffusivity inside the pericarp (Dep), mass transfer coefficient from the pericarp surface to the solvent (kc), and distribution coefficient (H). The model simulates the extraction per... [more]
Spatiotemporal Dynamics of Carbon Storage in Response to Urbanization: A Case Study in the Su-Xi-Chang Region, China
Qi Fu, Liangliang Xu, Hongyu Zheng, Jinhua Chen
December 16, 2019 (v1)
Subject: Energy Policy
Keywords: carbon storage, InVEST model, land-use change, spatiotemporal dynamics, urbanization
Terrestrial ecosystem carbon storage plays an important role in mitigating global warming. Understanding the characteristics and drivers of changes in carbon storage can provide a scientific basis for urban planning and management. The objective of this study was to reveal the ways in which urbanization influences the spatial and temporal variations in carbon storage. In this study, we investigated the changes in carbon storage from 1990−2000, 2000−2010, and 2010−2018 in the Su-Xi-Chang region, which is a typical fast-growing urban agglomeration in China, based on the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) model. Moreover, we analyzed the impacts of urbanization-induced land-use changes on carbon storage. The results showed that in terms of space and time, the greatest loss of carbon storage occurred in developing urban areas and during the rapidly urbanizing stage. Our study revealed that the reduction in cultivated land was the greatest contributor to carbo... [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]
Performance Evaluation Using Multivariate Non-Normal Process Capability
Moath Alatefi, Shafiq Ahmad, Mohammed Alkahtani
December 16, 2019 (v1)
Keywords: multivariate, non-normal data, process capability index, transformation techniques
Process capability indices (PCIs) have always been used to improve the quality of products and services. Traditional PCIs are based on the assumption that the data obtained from the quality characteristic (QC) under consideration are normally distributed. However, most data on manufacturing processes violate this assumption. Furthermore, the products and services of the manufacturing industry usually have more than one QC; these QCs are functionally correlated and, thus, should be evaluated together to evaluate the overall quality of a product. This study investigates and extends the existing multivariate non-normal PCIs. First, a multivariate non-normal PCI model from the literature is modeled and validated. An algorithm to generate non-normal multivariate data with the desired correlations is also modeled. Then, this model is extended using two different approaches that depend on the well-known Box−Cox and Johnson transformations. The skewness reduction is further improved by applyin... [more]
Esterification of Free Fatty Acids with Glycerol within the Biodiesel Production Framework
Juan Francisco García Martín, Javier Carrión Ruiz, Miguel Torres García, Chao-Hui Feng, Paloma Álvarez Mateos
December 16, 2019 (v1)
Keywords: biodiesel, esterification, free fatty acids, glycerol, waste cooking oil
Companies in the field of the collection and treatment of waste cooking oils (WCO) for subsequent biodiesel production usually have to cope with high acidity oils, which cannot be directly transformed into fatty acid methyl esters due to soap production. Since glycerine is the main byproduct of biodiesel production, these high acidity oils could be esterified with the glycerine surplus to transform the free fatty acids (FFA) into triglycerides before performing the transesterification. In this work, commercial glycerol was esterified with commercial fatty acids and commercial fatty acid/lampante olive oil mixtures over tin (II) chloride. In the first set of experiments, the esterification of linoleic acid with glycerol excess from 20 to 80% molar over the stoichiometric was performed. From 20% glycerol excess, there was no improvement in FFA reduction. Using 20% glycerol excess, the performance of a biochar obtained from heavy metal-contaminated plant roots was compared to that of SnCl... [more]
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