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Volume 8
Issue 9
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Processes, Volume 8, Issue 9 (September 2020) – 193 articles

Cover Story (view full-size image): Tortuosity is one of the most elusive parameters characterizing the geometrical properties of porous media. It may be calculated directly, based on the pure geometry of pore channels, or indirectly, based on transportation or diffusional properties of porous systems. Additionally, the geometry of porous media may be expressed in a vector, raster, or binary form, depending on the data origin. In the last case, the A-Star or the Patch Searching Algorithm may be used to calculate pore channel lengths and, in turn, the tortuosity value. Details are available in "Calculating the Binary Tortuosity in DEM-Generated Granular Beds". View this paper
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21 pages, 2390 KiB  
Article
A Representation of Membrane Computing with a Clustering Algorithm on the Graphical Processing Unit
by Ravie Chandren Muniyandi and Ali Maroosi
Processes 2020, 8(9), 1199; https://doi.org/10.3390/pr8091199 - 22 Sep 2020
Cited by 3 | Viewed by 2063
Abstract
Long-timescale simulations of biological processes such as photosynthesis or attempts to solve NP-hard problems such as traveling salesman, knapsack, Hamiltonian path, and satisfiability using membrane systems without appropriate parallelization can take hours or days. Graphics processing units (GPU) deliver an immensely parallel mechanism [...] Read more.
Long-timescale simulations of biological processes such as photosynthesis or attempts to solve NP-hard problems such as traveling salesman, knapsack, Hamiltonian path, and satisfiability using membrane systems without appropriate parallelization can take hours or days. Graphics processing units (GPU) deliver an immensely parallel mechanism to compute general-purpose computations. Previous studies mapped one membrane to one thread block on GPU. This is disadvantageous given that when the quantity of objects for each membrane is small, the quantity of active thread will also be small, thereby decreasing performance. While each membrane is designated to one thread block, the communication between thread blocks is needed for executing the communication between membranes. Communication between thread blocks is a time-consuming process. Previous approaches have also not addressed the issue of GPU occupancy. This study presents a classification algorithm to manage dependent objects and membranes based on the communication rate associated with the defined weighted network and assign them to sub-matrices. Thus, dependent objects and membranes are allocated to the same threads and thread blocks, thereby decreasing communication between threads and thread blocks and allowing GPUs to maintain the highest occupancy possible. The experimental results indicate that for 48 objects per membrane, the algorithm facilitates a 93-fold increase in processing speed compared to a 1.6-fold increase with previous algorithms. Full article
(This article belongs to the Special Issue Modeling, Simulation and Design of Membrane Computing System)
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29 pages, 7994 KiB  
Article
Design and Characterization of a Fluidic Device for the Evaluation of SIS-Based Vascular Grafts
by Alejandra Riveros, Monica Cuellar, Paolo F. Sánchez, Carolina Muñoz-Camargo, Juan C. Cruz, Néstor Sandoval, Omar D. Lopez Mejia and Juan C. Briceño
Processes 2020, 8(9), 1198; https://doi.org/10.3390/pr8091198 - 22 Sep 2020
Cited by 2 | Viewed by 2917
Abstract
Currently available small diameter vascular conduits present several long-term limitations, which has prevented their full clinical implementation. Commercially available vascular grafts show no regenerative capabilities and eventually require surgical replacement; therefore, it is of great interest to develop alternative regenerative vascular grafts (RVG). [...] Read more.
Currently available small diameter vascular conduits present several long-term limitations, which has prevented their full clinical implementation. Commercially available vascular grafts show no regenerative capabilities and eventually require surgical replacement; therefore, it is of great interest to develop alternative regenerative vascular grafts (RVG). Decellularized Small Intestinal Submucosa (SIS) is an attractive material for RVG, however, the evaluation of the performance of these grafts is challenging due to the absence of devices that mimic the conditions found in vivo. Thereby, the objective of this study is to design, manufacture and validate in silico and in vitro, a novel fluidic system for the evaluation of human umbilical vein endothelial cells (HUVECs) proliferation on SIS-based RVG under dynamical conditions. Our perfusion and rotational fluidic system was designed in Autodesk Inventor 2018. In silico Computational Fluid Dynamics (CFD) validation of the system was carried out using Ansys Fluent software from ANSYS, Inc for dynamical conditions of a pulsatile pressure function measured experimentally over a rigid wall model. Mechanical and biological parameters such as flow regime, pressure gradient, wall shear stress (WSS), sterility and indirect cell viability (MTT assay) were also evaluated. Cell adhesion was confirmed by SEM imaging. The fluid flow regime within the system remains laminar. The system maintained sterility and showed low cytotoxicity levels. HUVECs were successfully cultured on SIS-based RVG under both perfusion and rotation conditions. In silico analysis agreed well with our experimental and theoretical results, and with recent in vitro and in vivo reports for WSS. The system presented is a tool for evaluating RVG and represents an alternative to develop new methods and protocols for a more comprehensive study of regenerative cardiovascular devices. Full article
(This article belongs to the Section Biological Processes and Systems)
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18 pages, 5481 KiB  
Article
Enhanced Adsorptive Removal of β-Estradiol from Aqueous and Wastewater Samples by Magnetic Nano-Akaganeite: Adsorption Isotherms, Kinetics, and Mechanism
by Anele Mpupa, Azile Nqombolo, Boris Mizaikoff and Philiswa Nosizo Nomngongo
Processes 2020, 8(9), 1197; https://doi.org/10.3390/pr8091197 - 22 Sep 2020
Cited by 7 | Viewed by 2529
Abstract
A surfactant-free method was used to synthesize iron oxyhydroxide (akaganeite, β-FeOOH) nanorods and characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDS), and transmission electron microscopy (TEM). The synthesized nanoadsorbent was applied for [...] Read more.
A surfactant-free method was used to synthesize iron oxyhydroxide (akaganeite, β-FeOOH) nanorods and characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDS), and transmission electron microscopy (TEM). The synthesized nanoadsorbent was applied for the adsorptive removal of β-estradiol from aqueous solutions. The parameters affecting the adsorption were optimized using a multivariate approach based on the Box–Behnken design with the desirability function. Under the optimum conditions, the equilibrium data were investigated using two and three parameter isotherms, such as the Langmuir, Freundlich, Dubinin–Radushkevich, Redlich–Peterson, and Sips models. The adsorption data were described as Langmuir and Sips isotherm models and the maximum adsorption capacities in Langmuir and Sips of the β-FeOOH nanorods were 97.0 and 103 mg g−1, respectively. The adjusted non-linear adsorption capacities were 102 and 104 mg g−1 for Langmuir and Sips, respectively. The kinetics data were analyzed by five different kinetic models, such as the pseudo-first order, pseudo-second order, intraparticle, as well as Boyd and Elovich models. The method was applied for the removal β-estradiol in spiked recoveries of wastewater, river, and tap water samples, and the removal efficiency ranged from 93–100%. The adsorbent could be reused up to six times after regeneration with acetonitrile without an obvious loss in the removal efficiency (%RE = 95.4 ± 1.9%). Based on the results obtained, it was concluded that the β-FeOOH nanorods proved to be suitable for the efficient removal of β-estradiol from environmental matrices. Full article
(This article belongs to the Special Issue Various Adsorbents for Water Purification Processes)
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19 pages, 7386 KiB  
Article
Investigating the Use of Recycled Pork Fat-Based Biodiesel in Aviation Turbo Engines
by Grigore Cican, Marius Deaconu, Radu Mirea, Laurentiu Ceatra, Mihaiella Cretu and Tănase Dobre
Processes 2020, 8(9), 1196; https://doi.org/10.3390/pr8091196 - 21 Sep 2020
Cited by 12 | Viewed by 3099
Abstract
This paper presents an analysis of the possibility of using recycled pork fat-based biodiesel as fuel for aviation turbo-engines. The analysis consists of the assessment of four blends of Jet A kerosene with 10%, 30%, 50%, and 100% biodiesel and pure Jet A [...] Read more.
This paper presents an analysis of the possibility of using recycled pork fat-based biodiesel as fuel for aviation turbo-engines. The analysis consists of the assessment of four blends of Jet A kerosene with 10%, 30%, 50%, and 100% biodiesel and pure Jet A that was used as reference in the study. The first part of the paper presents the physical-chemical properties of the blends: density, viscosity, flash point, freezing point, and calorific power. Through Fourier transform infrared spectroscopy (FTIR) analysis, a benchmark was performed on the mixtures of Jet A with 10%, 20%, 30%, 50%, and 100% biodiesel compared with Jet A. The second part of the paper presents the test results of these blends used for fuelling a Jet Cat P80 turbo engine at the Turbo Engines Laboratory of the Aerospace Engineering Faculty of Polyethnic University of Bucharest. These functional tests were performed using different operating regimes as follows: idle, cruise, intermediate, and maximum. For each regime, a testing period of around 1 min was selected and the engine parameters were monitored during the test execution. The burning efficiency was calculated for the maximum regime for all mixtures. To evaluate the functioning stability of the turbo engine using biodiesel, two accelerometers were mounted on the engine support that recorded the radial and axial vibrations. Moreover, to assess the burning stability and to identify other acoustic spectral components when biodiesel is used, two microphones were placed near the jet region. A comparative analysis between blends was made by taking the Jet A fuel as reference. Full article
(This article belongs to the Special Issue Biomass Processing and Conversion Systems)
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20 pages, 2321 KiB  
Article
Curation and Analysis of a Saccharomyces cerevisiae Genome-Scale Metabolic Model for Predicting Production of Sensory Impact Molecules under Enological Conditions
by William T. Scott, Jr., Eddy J. Smid, Richard A. Notebaart and David E. Block
Processes 2020, 8(9), 1195; https://doi.org/10.3390/pr8091195 - 21 Sep 2020
Cited by 8 | Viewed by 4517
Abstract
One approach for elucidating strain-to-strain metabolic differences is the use of genome-scale metabolic models (GSMMs). To date GSMMs have not focused on the industrially important area of flavor production and, as such; do not cover all the pathways relevant to flavor formation in [...] Read more.
One approach for elucidating strain-to-strain metabolic differences is the use of genome-scale metabolic models (GSMMs). To date GSMMs have not focused on the industrially important area of flavor production and, as such; do not cover all the pathways relevant to flavor formation in yeast. Moreover, current models for Saccharomyces cerevisiae generally focus on carbon-limited and/or aerobic systems, which is not pertinent to enological conditions. Here, we curate a GSMM (iWS902) to expand on the existing Ehrlich pathway and ester formation pathways central to aroma formation in industrial winemaking, in addition to the existing sulfur metabolism and medium-chain fatty acid (MCFA) pathways that also contribute to production of sensory impact molecules. After validating the model using experimental data, we predict key differences in metabolism for a strain (EC 1118) in two distinct growth conditions, including differences for aroma impact molecules such as acetic acid, tryptophol, and hydrogen sulfide. Additionally, we propose novel targets for metabolic engineering for aroma profile modifications employing flux variability analysis with the expanded GSMM. The model provides mechanistic insights into the key metabolic pathways underlying aroma formation during alcoholic fermentation and provides a potential framework to contribute to new strategies to optimize the aroma of wines. Full article
(This article belongs to the Special Issue Role of Yeast in Wine Fermentation Processes)
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15 pages, 1646 KiB  
Article
Cu(II) and As(V) Adsorption Kinetic Characteristic of the Multifunctional Amino Groups in Chitosan
by Byungryul An
Processes 2020, 8(9), 1194; https://doi.org/10.3390/pr8091194 - 21 Sep 2020
Cited by 56 | Viewed by 3148
Abstract
Amino groups in the chitosan polymer play as a functional group for the removal of cations and anions depending on the degree of protonation, which is determined by the solution pH. A hydrogel beadlike porous adsorbent was used to investigate the functions and [...] Read more.
Amino groups in the chitosan polymer play as a functional group for the removal of cations and anions depending on the degree of protonation, which is determined by the solution pH. A hydrogel beadlike porous adsorbent was used to investigate the functions and adsorption mechanism of the amino groups by removal of Cu(II) as a cation and As(V) as an anion for a single and mixed solution. The uptakes of Cu(II) and As(V) were 5.2 and 5.6 μmol/g for the single solution and 5.9 and 3.6 μmol/g for the mixed solution, respectively. The increased total capacity in the presence of both the cation and anion indicated that the amino group (NH2 or NH3+) species was directly associated for adsorption. The application of a pseudo second-order (PSO) kinetic model was more suitable and resulted in an accurate correlation coefficient (R2) compared with the pseudo first-order (PFO) kinetic model for all experimental conditions. Due to poor linearization of the PFO reaction model, we attempted to divide it into two sections to improve the accuracy. Regardless of the model equation, the order of the rate constant was in the order of As(V)-single > Cu(II)-single > As(V)-mixed > Cu(II)-mixed. Also, the corresponding single solution and As(V) showed a higher adsorption rate. According to intraparticle and film diffusion applications displaying two linear lines and none passing through zero, the rate controlling step in the chitosan hydrogel bead was determined by both intraparticle and film diffusion. Full article
(This article belongs to the Special Issue Various Adsorbents for Water Purification Processes)
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16 pages, 3441 KiB  
Article
Analysis and Anticancer Effects of Active Compounds from Spatholobi Caulis in Human Breast Cancer Cells
by Hung Manh Phung, Hesol Lee, Sullim Lee, Dongyeop Jang, Chang-Eop Kim, Ki Sung Kang, Chang-Seob Seo and You-Kyung Choi
Processes 2020, 8(9), 1193; https://doi.org/10.3390/pr8091193 - 21 Sep 2020
Cited by 7 | Viewed by 4386
Abstract
Breast cancer is the most common malignancy in both developing and developed countries. In this study, we simultaneously analyzed nine constituent compounds from Spatholobi Caulis (gallic acid, (−)-gallocatechin, 3,4-dihydroxybenzoic acid, procyanidin B1, 3,4-dihydroxybenzaldehyde, catechin, procyanidin B2, epicatechin, and (−)-epicatechin gallate) and examined their [...] Read more.
Breast cancer is the most common malignancy in both developing and developed countries. In this study, we simultaneously analyzed nine constituent compounds from Spatholobi Caulis (gallic acid, (−)-gallocatechin, 3,4-dihydroxybenzoic acid, procyanidin B1, 3,4-dihydroxybenzaldehyde, catechin, procyanidin B2, epicatechin, and (−)-epicatechin gallate) and examined their anticancer effects on MCF-7 and MDA-MB-231 human breast cancer cells. The experimental results indicated that the gallic acid showed the strongest cytotoxic effect on MCF-7 cells among tested compounds whilst most of samples did not express inhibitory effect on viability of MDA-MB-231 cells, except for 70% ethanol extract of S. Caulis. Thus, gallic acid was chosen to extend anticancer mechanism study on MCF-7 cells. Our data showed that the gallic acid induced apoptotic MCF-7 cell death through both extrinsic and intrinsic pathways, which increased the expression of cleaved caspase-7, -8, and -9, Bax and p53, but reduced the expression of Bcl-2 and poly (ADP-ribose) polymerase (PARP). In addition, the network pharmacological analysis pointed out that the p53, mitogen-activated protein kinase (MAPK), estrogen, and Wnt signaling pathways have a great correlation with the targets of gallic acid. This study suggested that gallic acid is a bioactive component of S. Caulis with potential to be used in chemotherapy for breast cancer. Full article
(This article belongs to the Special Issue Metabolic Analysis in Food Processing)
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15 pages, 8188 KiB  
Article
Numerical Simulation of Axial Vortex in a Centrifugal Pump as Turbine with S-Blade Impeller
by Xiaohui Wang, Kailin Kuang, Zanxiu Wu and Junhu Yang
Processes 2020, 8(9), 1192; https://doi.org/10.3390/pr8091192 - 20 Sep 2020
Cited by 18 | Viewed by 3639
Abstract
Pump as turbines (PATs) are widely applied for recovering the dissipated energy of high-pressure fluids in several hydraulic energy resources. When a centrifugal pump operates as turbine, the large axial vortex occurs usually within the impeller flow passages. In view of the structure [...] Read more.
Pump as turbines (PATs) are widely applied for recovering the dissipated energy of high-pressure fluids in several hydraulic energy resources. When a centrifugal pump operates as turbine, the large axial vortex occurs usually within the impeller flow passages. In view of the structure and evolution of the vortex, and its effect on pressure fluctuation and energy conversion of the machine, a PAT with specific-speed 9.1 was analyzed based on detached eddy simulation (DES), and the results showed that vortices generated at the impeller inlet region, and the size and position of detected vortices, were fixed as the impeller rotated. However, the swirling strength of vortex cores changed periodically with double rotational frequency. The influence of vortices on pressure fluctuation of PAT was relatively obvious, deteriorating the operating stability of the machine evidently. In addition, the power loss near impeller inlet region was obviously heavy as the impact of large axial vortices, which was much more serious in low flow rate conditions. The results are helpful to realize the flow field of PAT and are instructive for blade optimization design. Full article
(This article belongs to the Special Issue CFD Based Researches and Applications for Fluid Machinery and Fluid Device)
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10 pages, 2904 KiB  
Article
Inhibitory Effects of Thymol Isolated from Curcuma longa L. on Adipogenesis in HepG2 Cells
by Dam-Hee Kang, Young-Seob Lee, Seon Min Oh, Dahye Yoon, Doo Jin Choi, Dong-Yeul Kwon, Ok-Hwa Kang and Dae Young Lee
Processes 2020, 8(9), 1191; https://doi.org/10.3390/pr8091191 - 20 Sep 2020
Cited by 3 | Viewed by 2918
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a disease associated with metabolic syndromes such as diabetes and obesity, regardless of alcohol consumption, and refers to the accumulation of triacylglycerols in the liver. Thymol (THY) is a vegetable essential oil that is naturally contained in [...] Read more.
Non-alcoholic fatty liver disease (NAFLD) is a disease associated with metabolic syndromes such as diabetes and obesity, regardless of alcohol consumption, and refers to the accumulation of triacylglycerols in the liver. Thymol (THY) is a vegetable essential oil that is naturally contained in the Zingiberaceae and Lamiaceae families. THY was isolated from Curcuma longa L. The rhizomes of Curcuma longa L. were dried, sliced and extracted with 50% ethanol and then isolated through repeated column chromatography. This study was conducted to investigate the inhibitory effect of THY, even in non-alcoholic fatty liver disease, in relation to the inhibiting hyperlipidemia effect of THY, which was demonstrated in previous studies. Hepatocytes were treated with oleate (OA) containing THY to observe lipid accumulation by Oil Red O staining (ORO). We also tested the effect of THY on triacylglycerols (TG) and total cholesterol (TC) in HepG2 cells. Western blot and real-time RT-PCR using sterol regulatory element-binding protein-1c (SREBP-1c), fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), CCAAT-enhancer-binding protein (C/EBP), proliferator-activated receptor γ (PPARγ), and adenosine monophosphate (AMP)-activated protein kinase (AMPK) expressions were carried out. Consequently, inhibition of lipogenesis by THY (100 μM or 200 μM) in NAFLD treated with OA in HepG2 cells was confirmed. The results of TG and TC experiments confirmed a decrease in the degree of fat accumulation in the liver. Furthermore, inhibition of the SREBP-1c, FAS, ACC, C/EBP and PPARγ expressions that mediated fat accumulation and increased AMPK phosphorylation was observed. Taken together, THY is proposed as a potential natural constituent for the treatment of NAFLD. Full article
(This article belongs to the Special Issue Metabolic Analysis in Food Processing)
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17 pages, 1374 KiB  
Review
Microwave-Assisted Pyrolysis of Biomass Waste: A Mini Review
by Saleem Ethaib, Rozita Omar, Siti Mazlina Mustapa Kamal, Dayang Radiah Awang Biak and Salah L. Zubaidi
Processes 2020, 8(9), 1190; https://doi.org/10.3390/pr8091190 - 19 Sep 2020
Cited by 70 | Viewed by 11853
Abstract
The utilization of biomass waste as a raw material for renewable energy is a global concern. Pyrolysis is one of the thermal treatments for biomass wastes that results in the production of liquid, solid and gaseous products. Unfortunately, the complex structure of the [...] Read more.
The utilization of biomass waste as a raw material for renewable energy is a global concern. Pyrolysis is one of the thermal treatments for biomass wastes that results in the production of liquid, solid and gaseous products. Unfortunately, the complex structure of the biomass materials matrix needs elevated heating to convert these materials into useful products. Microwave heating is a promising alternative to conventional heating approaches. Recently, it has been widely used in pyrolysis due to easy operation and its high heating rate. This review tries to identify the microwave-assisted pyrolysis treatment process fundamentals and discusses various key operating parameters which have an effect on product yield. It was found that several operating parameters govern this process such as microwave power and the degree of temperature, microwave absorber addition and its concentration, initial moisture content, initial sweep gas flow rate/residence time. Moreover, this study highlighted the most attractive products of the microwave pyrolysis process. These products include synthesis gas, bio-char, and bio-oil. The benefits and challenges of microwave heating are discussed. Full article
(This article belongs to the Section Environmental and Green Processes)
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18 pages, 2259 KiB  
Article
Carbon-Efficient Production Scheduling of a Bioethanol Plant Considering Diversified Feedstock Pelletization Density: A Case Study
by Xinchao Li, Xin Jin, Shan Lu, Zhe Li, Yue Wang and Jiangtao Cao
Processes 2020, 8(9), 1189; https://doi.org/10.3390/pr8091189 - 18 Sep 2020
Cited by 1 | Viewed by 2292
Abstract
This paper presents a dual-objective optimization model for production scheduling of bioethanol plant with carbon-efficient strategies. The model is developed throughout the bioethanol production process. Firstly, the production planning and scheduling of the bioethanol plant’s transportation, storage, pretreatment, and ethanol manufacturing are fully [...] Read more.
This paper presents a dual-objective optimization model for production scheduling of bioethanol plant with carbon-efficient strategies. The model is developed throughout the bioethanol production process. Firstly, the production planning and scheduling of the bioethanol plant’s transportation, storage, pretreatment, and ethanol manufacturing are fully considered. Secondly, the carbon emissions in the ethanol manufacturing process are integrated into the model to form a dual-objective optimization model that simultaneously optimizes the production plan and carbon emissions. The effects of different biomass raw materials with optional pelletization density and pretreatment methods on production scheduling are analyzed. The influence of demand and pretreatment cost on selecting a pretreatment method and total profit is considered. A membership weighted method is developed to solve the dual-objective model. The carbon emission model and economic model are integrated into one model for analysis. An example is given to verify the effectiveness of the optimization model. At the end of the paper, the limitation of this study is discussed to provide directions for future research. Full article
(This article belongs to the Section Environmental and Green Processes)
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22 pages, 9563 KiB  
Article
Potential Dynamics of CO2 Stream Composition and Mass Flow Rates in CCS Clusters
by Sven-Lasse Kahlke, Martin Pumpa, Stefan Schütz, Alfons Kather and Heike Rütters
Processes 2020, 8(9), 1188; https://doi.org/10.3390/pr8091188 - 18 Sep 2020
Cited by 5 | Viewed by 2760
Abstract
Temporal variations in CO2 stream composition and mass flow rates may occur in a CO2 transport network, as well as further downstream when CO2 streams of different compositions and temporally variable mass flow rates are fed in. To assess the [...] Read more.
Temporal variations in CO2 stream composition and mass flow rates may occur in a CO2 transport network, as well as further downstream when CO2 streams of different compositions and temporally variable mass flow rates are fed in. To assess the potential impacts of such variations on CO2 transport, injection, and storage, their characteristics must be known. We investigated variation characteristics in a scenario of a regional CO2 emitter cluster of seven fossil-fired power plants and four industrial plants that feed captured CO2 streams into a pipeline network. Variations of CO2 stream composition and mass flow rates in the pipelines were simulated using a network analysis tool. In addition, the potential effects of changes in the energy mix on resulting mass flow rates and CO2 stream compositions were investigated for two energy mix scenarios that consider higher shares of renewable energy sources or a replacement of lignite by hard coal and natural gas. While resulting maximum mass flow rates in the trunk line were similar in all considered scenarios, minimum flow rates and pipeline capacity utilisation differed substantially between them. Variations in CO2 stream composition followed the power plants’ operational load patterns resulting e.g., in stronger composition variations in case of higher renewable energy production. Full article
(This article belongs to the Special Issue Carbon Capture, Utilization and Storage Technology)
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11 pages, 1110 KiB  
Article
Experimental Investigation of Stability of Vegetable Oils Used as Dielectric Fluids for Electrical Discharge Machining
by Maria-Crina Radu, Raluca Tampu, Valentin Nedeff, Oana-Irina Patriciu, Carol Schnakovszky and Eugen Herghelegiu
Processes 2020, 8(9), 1187; https://doi.org/10.3390/pr8091187 - 18 Sep 2020
Cited by 14 | Viewed by 2806
Abstract
One main drawback of electrical discharge machining (EDM) is related to the dielectric fluid, since it impacts both the environment and operator health and safety. To resolve these issues, recent research has demonstrated the technical feasibility and qualitative performance of vegetable oils as [...] Read more.
One main drawback of electrical discharge machining (EDM) is related to the dielectric fluid, since it impacts both the environment and operator health and safety. To resolve these issues, recent research has demonstrated the technical feasibility and qualitative performance of vegetable oils as substitutes for hydrocarbon-based dielectric and synthetic oils in EDM. However, due to the higher content of unsaturated fatty acids, vegetable oils lose their stability, due to several factors such as heating or exposure to light or oxygen. The present study is a first attempt to analyze the extent to which the physic-chemical properties of vegetable oils change during EDM processing. Refractive index, dynamic viscosity and spectra analyses were conducted for sunflower and soybean oils. The results revealed that, under the applied processing conditions, no structural changes occurred. These findings are very promising from the perspective of EDM sustainability. Full article
(This article belongs to the Section Environmental and Green Processes)
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11 pages, 1405 KiB  
Article
Maintaining Physicochemical, Microbiological, and Sensory Quality of Pineapple Juice (Ananas comosus, Var. ‘Queen Victoria’) through Mild Heat Treatment
by Charlène Leneveu-Jenvrin, Baptiste Quentin, Sophie Assemat and Fabienne Remize
Processes 2020, 8(9), 1186; https://doi.org/10.3390/pr8091186 - 18 Sep 2020
Cited by 13 | Viewed by 5293
Abstract
Shelf life of freshly prepared pineapple juice is short and requires refrigerated conditions of storage. Mild heat treatment remains the easiest way to prolong juice shelf life for small companies. This study was constructed to assess pineapple cv. Queen Victoria juice shelf life [...] Read more.
Shelf life of freshly prepared pineapple juice is short and requires refrigerated conditions of storage. Mild heat treatment remains the easiest way to prolong juice shelf life for small companies. This study was constructed to assess pineapple cv. Queen Victoria juice shelf life from a broad examination of its quality and to propose the most appropriate thermal treatment to increase shelf life without any perceptible decrease in quality. From 25 independent batches of pineapple, collected in different areas and seasons from Reunion Island, the variability of juice physicochemical and microbiological quality was determined. Juice pH values were the highest for fruit harvested in summer, but the juice acidity remained low enough to prevent pathogen spore-forming bacteria growth. During storage at 4 °C, color was modified, and yeasts and molds were the main microbial group exhibiting growth. Assessment of sensory quality resulted in the proposal of a shelf life comprising between three and seven days. Compared to higher temperatures, heat treatment at 60 °C was enough to ensure a good microbiological quality for 30 days, but sensory characteristics and color changes led to the proposal of a shelf life of seven days for pineapple juice treated at 60 °C. Full article
(This article belongs to the Special Issue Processing Foods: Process Optimization and Quality Assessment)
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18 pages, 3405 KiB  
Article
Finite Element Study of Magnetohydrodynamics (MHD) and Activation Energy in Darcy–Forchheimer Rotating Flow of Casson Carreau Nanofluid
by Bagh Ali, Ghulam Rasool, Sajjad Hussain, Dumitru Baleanu and Sehrish Bano
Processes 2020, 8(9), 1185; https://doi.org/10.3390/pr8091185 - 18 Sep 2020
Cited by 52 | Viewed by 2594
Abstract
Here, a study for MHD (magnetohydrodynamic) impacts on the rotating flow of Casson Carreau nanofluids is considered. The temperature distribution is associated with thermophoresis, Brownian motion, and heat source. The diffusion of chemically reactive specie is investigated with Arrhenius activation energy. The governing [...] Read more.
Here, a study for MHD (magnetohydrodynamic) impacts on the rotating flow of Casson Carreau nanofluids is considered. The temperature distribution is associated with thermophoresis, Brownian motion, and heat source. The diffusion of chemically reactive specie is investigated with Arrhenius activation energy. The governing equations in the 3D form are changed into dimensionless two-dimensional form with the implementation of suitable scaling transformations. The Variational finite element procedure is harnessed and coded in Matlab script to obtain the numerical solution of the coupled non-linear partial differential problem. The variation patterns of Sherwood number, Nusselt number, skin friction coefficients, velocities, concentration, and temperature functions are computed to reveal the physical nature of this examination. It is seen that higher contributions of the magnetic force, Casson fluid, and rotational fluid parameters cause a raise in the temperature like thermophoresis and Brownian motion does but also causes a slowing down in the primary as well as secondary velocities. The FEM solutions show an excellent correlation with published results. The current study has significant applications in the biomedical, modern technologies of aerospace systems, and relevance to energy systems. Full article
(This article belongs to the Section Advanced Digital and Other Processes)
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23 pages, 3947 KiB  
Article
Methodology to Solve the Multi-Objective Optimization of Acrylic Acid Production Using Neural Networks as Meta-Models
by Geraldine Cáceres Sepulveda, Silvia Ochoa and Jules Thibault
Processes 2020, 8(9), 1184; https://doi.org/10.3390/pr8091184 - 18 Sep 2020
Cited by 4 | Viewed by 2785
Abstract
It is paramount to optimize the performance of a chemical process in order to maximize its yield and productivity and to minimize the production cost and the environmental impact. The various objectives in optimization are often in conflict, and one must determine the [...] Read more.
It is paramount to optimize the performance of a chemical process in order to maximize its yield and productivity and to minimize the production cost and the environmental impact. The various objectives in optimization are often in conflict, and one must determine the best compromise solution usually using a representative model of the process. However, solving first-principle models can be a computationally intensive problem, thus making model-based multi-objective optimization (MOO) a time-consuming task. In this work, a methodology to perform the multi-objective optimization for a two-reactor system for the production of acrylic acid, using artificial neural networks (ANNs) as meta-models, is proposed in an effort to reduce the computational time required to circumscribe the Pareto domain. The performance of the meta-model confirmed good agreement between the experimental data and the model-predicted values of the existent relationships between the eight decision variables and the nine performance criteria of the process. Once the meta-model was built, the Pareto domain was circumscribed based on a genetic algorithm (GA) and ranked with the net flow method (NFM). Using the ANN surrogate model, the optimization time decreased by a factor of 15.5. Full article
(This article belongs to the Collection Multi-Objective Optimization of Processes)
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24 pages, 1582 KiB  
Article
PID Tuning Method Based on IMC for Inverse-Response Second-Order Plus Dead Time Processes
by Duby Castellanos-Cárdenas, Fabio Castrillón, Rafael E. Vásquez and Carlos Smith
Processes 2020, 8(9), 1183; https://doi.org/10.3390/pr8091183 - 18 Sep 2020
Cited by 7 | Viewed by 5019
Abstract
This work addresses a set of tuning rules for PID controllers based on Internal Model Control (IMC) for inverse-response second-order systems with dead time. The transfer function, and some time-response characteristics for such systems are first described. Then, the IMC-based methodology is developed [...] Read more.
This work addresses a set of tuning rules for PID controllers based on Internal Model Control (IMC) for inverse-response second-order systems with dead time. The transfer function, and some time-response characteristics for such systems are first described. Then, the IMC-based methodology is developed by using an optimization objective function that mixes performance and robustness. A correlation that minimizes the objective function and that allows the user to compute the controller’s tuning parameter is found. The obtained expressions are mathematically simple, which facilitate their application in a ten-step systematic methodology. Finally, the proposed tuning method is compared to other well-known tuning rules that have been reported in literature, for a wide range of parameters of the process. The performance achieved with the proposed method is very good not only for disturbance rejection but for set-point tracking, when considering a wide-range of parameters of the process’ transfer function. Full article
(This article belongs to the Section Process Control and Monitoring)
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20 pages, 3207 KiB  
Article
Life-Cycle Assessment of Dairy Products—Case Study of Regional Cheese Produced in Portugal
by Óscar Soares Nunes, Pedro Dinis Gaspar, José Nunes, Paula Quinteiro, Ana Cláudia Dias and Radu Godina
Processes 2020, 8(9), 1182; https://doi.org/10.3390/pr8091182 - 18 Sep 2020
Cited by 6 | Viewed by 5645
Abstract
Nowadays, there is a growing promotion to label products ecologically in European markets. Knowing that daily products have relevant environmental impact associated with their production, it is of utmost importance to analyse all the related production processes for a better understanding of each [...] Read more.
Nowadays, there is a growing promotion to label products ecologically in European markets. Knowing that daily products have relevant environmental impact associated with their production, it is of utmost importance to analyse all the related production processes for a better understanding of each process impact. The present study analysed the potential environmental impacts of a Portuguese regional product, the Beira Baixa cheese, coming from the largest national sheep milk region. So, a life cycle assessment (LCA) methodology is used from -cradle-to -gate, including the supplying of the animal feedstock. Impact calculations are performed using the ReCiPe midpoint 2008 method, allowing an analysis of the environmental impacts contributing to climate change, terrestrial acidification, freshwater and marine eutrophication of all productive processes. The results have shown that the greatest impacts occur within the milk production process for all four selected impact categories. This happens mainly due to the fodder cultivation process, also necessary to produce animal feed, which contain processes of fertilization and land preparation. The enteric fermentation and manure management processes have also shown relevant contributions. The impact assessment also showed that the cheesemaking industry has practically insignificant impacts. Nonetheless, the cheesemaking industry can promote their business with these results, by advertising and marketing their product as environmentally friendly, with production processes causing reduced impacts, and therefore also their products. Full article
(This article belongs to the Special Issue Sustainable Development of Waste towards Green Growth)
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18 pages, 7796 KiB  
Article
Degradation of Direct Blue 1 through Heterogeneous Photocatalysis with TiO2 Irradiated with E-Beam
by Elvia Gallegos, Florinella Muñoz Bisesti, Katherine Vaca-Escobar, Cristian Santacruz, Lenys Fernández, Alexis Debut and Patricio J. Espinoza-Montero
Processes 2020, 8(9), 1181; https://doi.org/10.3390/pr8091181 - 18 Sep 2020
Cited by 5 | Viewed by 3094
Abstract
Most dyes used in the textile industry are chemically stable and poorly biodegradable, therefore, they are persistent in the environment and difficult to degrade by conventional methods. An alternative treatment for this kind of substance is heterogeneous photocatalysis using TiO2, so, [...] Read more.
Most dyes used in the textile industry are chemically stable and poorly biodegradable, therefore, they are persistent in the environment and difficult to degrade by conventional methods. An alternative treatment for this kind of substance is heterogeneous photocatalysis using TiO2, so, in this work, it is proposed to degrade Direct Blue 1 (DB1) using microparticulate TiO2 irradiated with e-beam at three different doses: 5, 10 and 20 kGy (J/kg). The DB1 degradation was implemented in a batch reactor (DB1 initial concentration = 50 mg L−1, pH 2.5, TiO2 concentration = 200 mg L−1). We have demonstrated that the photocatalytic power of TiO2, when irradiated with e-beam (5, 10, 20 kGy), varies slightly, with minor effects on photodegradation performance. However, the dose of 10 kGy showed a slightly better result, according to the DB1 photodegradation rate constant. Adsorption process was not affected by irradiation; its isotherm was fitted to Freundlich’s mathematical model. The DB1 photodegradation rate constants, after one hour of treatment, were: 0.0661 and 0.0742 min−1 for irradiated (10 kGy) and nonirradiated TiO2, respectively. The degradation rate constant has an increase of 12.3% for irradiated TiO2. Finally, there was no evidence of mineralization in the degradation process after 60 min of treatment. According to the results, the irradiation of microparticulate TiO2 with e-beam (10 kGy) slightly improves the photodegradation rate constant of DB1. Full article
(This article belongs to the Special Issue Photocatalytic Processes for Environmental Applications)
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16 pages, 4599 KiB  
Article
SuperPro Designer®, User-Oriented Software Used for Analyzing the Techno-Economic Feasibility of Electrical Energy Generation from Sugarcane Vinasse in Colombia
by Licelly Canizales, Fredy Rojas, Carlos A. Pizarro, Nelson. H. Caicedo-Ortega and M. F. Villegas-Torres
Processes 2020, 8(9), 1180; https://doi.org/10.3390/pr8091180 - 18 Sep 2020
Cited by 18 | Viewed by 9532
Abstract
SuperPro Designer® is a process simulator software used for analyzing the techno-economic feasibility of large-scale bioprocesses. Its predetermined built-in features allow for easy implementation by non-experts, but a lack of examples limits its appropriation. This study aims to validate the implementation of [...] Read more.
SuperPro Designer® is a process simulator software used for analyzing the techno-economic feasibility of large-scale bioprocesses. Its predetermined built-in features allow for easy implementation by non-experts, but a lack of examples limits its appropriation. This study aims to validate the implementation of SuperPro Designer® by non-experts for the techno-economic analysis of anaerobic digestion in Colombia, using vinasse as feedstock. These results demonstrate the financial feasibility of such a process when a processing flow rate of 25 m3/h is ensured. Additionally, this study validates the manageability of the tool for assessing the economic feasibility of a technology, a key practice during technology development regardless of the area of expertise. Full article
(This article belongs to the Special Issue Biomass to Renewable Energy Processes)
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31 pages, 4801 KiB  
Article
High-Throughput Raman Spectroscopy Combined with Innovate Data Analysis Workflow to Enhance Biopharmaceutical Process Development
by Stephen Goldrick, Alexandra Umprecht, Alison Tang, Roman Zakrzewski, Matthew Cheeks, Richard Turner, Aled Charles, Karolina Les, Martyn Hulley, Chris Spencer and Suzanne S. Farid
Processes 2020, 8(9), 1179; https://doi.org/10.3390/pr8091179 - 17 Sep 2020
Cited by 24 | Viewed by 8330
Abstract
Raman spectroscopy has the potential to revolutionise many aspects of biopharmaceutical process development. The widespread adoption of this promising technology has been hindered by the high cost associated with individual probes and the challenge of measuring low sample volumes. To address these issues, [...] Read more.
Raman spectroscopy has the potential to revolutionise many aspects of biopharmaceutical process development. The widespread adoption of this promising technology has been hindered by the high cost associated with individual probes and the challenge of measuring low sample volumes. To address these issues, this paper investigates the potential of an emerging new high-throughput (HT) Raman spectroscopy microscope combined with a novel data analysis workflow to replace off-line analytics for upstream and downstream operations. On the upstream front, the case study involved the at-line monitoring of an HT micro-bioreactor system cultivating two mammalian cell cultures expressing two different therapeutic proteins. The spectra generated were analysed using a partial least squares (PLS) model. This enabled the successful prediction of the glucose, lactate, antibody, and viable cell density concentrations directly from the Raman spectra without reliance on multiple off-line analytical devices and using only a single low-volume sample (50–300 μL). However, upon the subsequent investigation of these models, only the glucose and lactate models appeared to be robust based upon their model coefficients containing the expected Raman vibrational signatures. On the downstream front, the HT Raman device was incorporated into the development of a cation exchange chromatography step for an Fc-fusion protein to compare different elution conditions. PLS models were derived from the spectra and were found to predict accurately monomer purity and concentration. The low molecular weight (LMW) and high molecular weight (HMW) species concentrations were found to be too low to be predicted accurately by the Raman device. However, the method enabled the classification of samples based on protein concentration and monomer purity, allowing a prioritisation and reduction in samples analysed using A280 UV absorbance and high-performance liquid chromatography (HPLC). The flexibility and highly configurable nature of this HT Raman spectroscopy microscope makes it an ideal tool for bioprocess research and development, and is a cost-effective solution based on its ability to support a large range of unit operations in both upstream and downstream process operations. Full article
(This article belongs to the Special Issue Measurement Technologies for up- and Downstream Bioprocessing)
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16 pages, 3911 KiB  
Article
A Numerical Investigation on De-NOx Technology and Abnormal Combustion Control for a Hydrogen Engine with EGR System
by Hao Guo, Song Zhou, Jiaxuan Zou and Majed Shreka
Processes 2020, 8(9), 1178; https://doi.org/10.3390/pr8091178 - 17 Sep 2020
Cited by 18 | Viewed by 3692
Abstract
The combustion emissions of the hydrogen-fueled engines are very clean, but the problems of abnormal combustion and high NOx emissions limit their applications. Nowadays hydrogen engines use exhaust gas recirculation (EGR) technology to control the intensity of premixed combustion and reduce the NOx [...] Read more.
The combustion emissions of the hydrogen-fueled engines are very clean, but the problems of abnormal combustion and high NOx emissions limit their applications. Nowadays hydrogen engines use exhaust gas recirculation (EGR) technology to control the intensity of premixed combustion and reduce the NOx emissions. This study aims at improving the abnormal combustion and decreasing the NOx emissions of the hydrogen engine by applying a three-dimensional (3D) computational fluid dynamics (CFD) model of a single-cylinder hydrogen-fueled engine equipped with an EGR system. The results indicated that peak in-cylinder pressure continuously increased with the increase of the ignition advance angle and was closer to the top dead center (TDC). In addition, the mixture was burned violently near the theoretical air–fuel ratio, and the combustion duration was shortened. Moreover, the NOx emissions, the average pressure, and the in-cylinder temperature decreased as the EGR ratio increased. Furthermore, increasing the EGR ratio led to an increase in the combustion duration and a decrease in the peak heat release rate. EGR system could delay the spontaneous combustion reaction of the end-gas and reduce the probability of knocking. The pressure rise rate was controlled and the in-cylinder hot spots were reduced by the EGR system, which could suppress the occurrence of the pre-ignition in the hydrogen engine. Full article
(This article belongs to the Special Issue Modelling, Simulation and Control in Combustion Processes of Renewable Fuels)
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18 pages, 2189 KiB  
Review
Olive Tree Leaves—A Source of Valuable Active Compounds
by Fereshteh Safarzadeh Markhali, José A. Teixeira and Cristina M. R. Rocha
Processes 2020, 8(9), 1177; https://doi.org/10.3390/pr8091177 - 17 Sep 2020
Cited by 58 | Viewed by 10553
Abstract
The agricultural and processing activities of olive crops generate a substantial amount of food by-products, particularly olive leaves, which are mostly underexploited, representing a significant threat to the environment. Olive leaves are endowed with endogenous bioactive compounds. Their beneficial/health-promoting potential, together with environmental [...] Read more.
The agricultural and processing activities of olive crops generate a substantial amount of food by-products, particularly olive leaves, which are mostly underexploited, representing a significant threat to the environment. Olive leaves are endowed with endogenous bioactive compounds. Their beneficial/health-promoting potential, together with environmental protection and circular economy, merit their exploitation to recover and reuse natural components that are potentially safer alternatives to synthetic counterparts. These biomass residues have great potential for extended industrial applications in food/dietary systems but have had limited commercial uses so far. In this regard, many researchers have endeavoured to determine a green/sustainable means to replace the conventional/inefficient methods currently used. This is not an easy task as a sustainable bio-processing approach entails careful designing to maximise the liberation of compounds with minimum use of (i) processing time, (ii) toxic solvent (iii) fossil fuel energy, and (iv) overall cost. Thus, it is necessary to device viable strategies to (i) optimise the extraction of valuable biomolecules from olive leaves and enable their conversion into high added-value products, and (ii) minimise generation of agro-industrial waste streams. This review provides an insight to the principal bioactive components naturally present in olive leaves, and an overview of the existing/proposed methods associated with their analysis, extraction, applications, and stability. Full article
(This article belongs to the Special Issue Sustainable Development of Waste towards Green Growth)
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13 pages, 2158 KiB  
Article
Preparation and Characterization of New Electrically Conductive Composites Based on Expanded Graphite with Potential Use as Remote Environmental Detectors
by Martin Prostredný, Igor Krupa and Zdenko Špitalský
Processes 2020, 8(9), 1176; https://doi.org/10.3390/pr8091176 - 17 Sep 2020
Viewed by 1890
Abstract
The presented paper is focused on studying electrically conductive composites based on an elastomeric matrix and expanded graphite as the filler. A potential application as an environmental remote detector was studied. The influence of filler particle size, film thickness, detector length, temperature, and [...] Read more.
The presented paper is focused on studying electrically conductive composites based on an elastomeric matrix and expanded graphite as the filler. A potential application as an environmental remote detector was studied. The influence of filler particle size, film thickness, detector length, temperature, and the amount of oil on the detector response rate were explored. Peel tests were performed in order to investigate the adhesion of prepared detector films to different materials. Expanded graphite with average particle size 5 µm was chosen for the experiments due to its fastest response. Decreasing the detector film thickness has caused an increase in the response rate but also a decrease in the signal measured. The response rate of the detector system was in a practical range even for lower temperatures. From the obtained data, the proposed detector seems to be suitable for a practical application. Full article
(This article belongs to the Section Materials Processes)
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16 pages, 2539 KiB  
Article
Phytotoxicity and Effect of Ionic Liquids on Antioxidant Parameters in Spring Barley Seedlings: The Impact of Exposure Time
by Robert Biczak, Barbara Pawłowska, Wiesław Pilis, Jan Szczegielniak, Jacek Wróbel and Arkadiusz Telesiński
Processes 2020, 8(9), 1175; https://doi.org/10.3390/pr8091175 - 17 Sep 2020
Cited by 6 | Viewed by 2129
Abstract
The influence of the ionic liquids (ILs) tetrabutylammonium bromide [TBA][Br], 1-butyl-3-methylimidazole bromide [BMIM][Br], and tetrabutylphosphonium bromide [TBP][Br] added at different concentrations to the soil were studied for the growth and development of spring barley seedlings. Samples were harvested at three different time points: [...] Read more.
The influence of the ionic liquids (ILs) tetrabutylammonium bromide [TBA][Br], 1-butyl-3-methylimidazole bromide [BMIM][Br], and tetrabutylphosphonium bromide [TBP][Br] added at different concentrations to the soil were studied for the growth and development of spring barley seedlings. Samples were harvested at three different time points: day 7, 14, and 21 after addition of ILs. The results show that [TBP][Br] was the most toxic. The introduction of this IL at the dose of 100 mg kg−1 of soil DM decreased the growth of seedlings at all test dates. The addition of the studied ILs to the soil in higher doses resulted in an increase in peroxidase and catalase activity, which may indicate the occurrence of oxidative stress in plants. An increase in the content of plant dry matter weight, contents of H2O2 and proline and a decrease in the content of photosynthetic pigments in barley seedlings were also observed. The malondialdehyde content and superoxide dismutase activity fluctuated randomly during the experiment. As a result, it was found that the phytotoxicity of ILs and the magnitude of oxidative stress in seedlings depended more on the added doses of these compounds than on the measurement date. Full article
(This article belongs to the Special Issue Applications of Bioprocess Processes in Environmental Protection and Purification)
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32 pages, 636 KiB  
Review
Scope and Limitations of the Mathematical Models Developed for the Forward Feed Multi-Effect Distillation Process—A Review
by Omer Mohamed Abubaker Al-Hotmani, Mudhar Abdul Alwahab Al-Obaidi, Yakubu Mandafiya John, Raj Patel and Iqbal M Mujtaba
Processes 2020, 8(9), 1174; https://doi.org/10.3390/pr8091174 - 17 Sep 2020
Cited by 5 | Viewed by 4041
Abstract
Desalination has become one of the obvious solutions for the global water crisis due to affording high-quality water from seawater and brackish water resources. As a result, there are continuing efforts being made to improve desalination technologies, especially the one producing high-quantity freshwater, [...] Read more.
Desalination has become one of the obvious solutions for the global water crisis due to affording high-quality water from seawater and brackish water resources. As a result, there are continuing efforts being made to improve desalination technologies, especially the one producing high-quantity freshwater, i.e., thermal desalination. This improvement must be accomplished via enhancement of process design through optimization which is implicitly dependent on providing a generic process model. Due to the scarcity of a comprehensive review paper for modeling multi-effect distillation (MED) process, this topic is becoming more important. Therefore, this paper intends to capture the evolution of modeling the forward feed MED (most common type) and shed a light on its branches of steady-state and dynamic modeling. The maturity of the models developed for MED will be thoroughly reviewed to clarify the general efforts made highlighting the advantages and disadvantages. Depending on the outputs of this review, the requirements of process development and emerging challengeable matters of modeling will be specified. This, in turn, would afford a possible improvement strategy to gain a reliable and sustainable thermal desalination process. Full article
(This article belongs to the Special Issue Feature Review Papers)
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21 pages, 1337 KiB  
Review
Antibacterial Activity of Chitosan Nanoparticles: A Review
by Murugesan Chandrasekaran, Ki Deok Kim and Se Chul Chun
Processes 2020, 8(9), 1173; https://doi.org/10.3390/pr8091173 - 17 Sep 2020
Cited by 159 | Viewed by 13724
Abstract
In recent years, nanotechnology has attracted attention in many fields because it has several up-and-coming novel uses. Many researchers have suggested that chitosan nanoparticles (CS-NPs) and their derivatives are one of the best nanomaterials for delivering antibacterial activity. CS-NPs have a broad spectrum [...] Read more.
In recent years, nanotechnology has attracted attention in many fields because it has several up-and-coming novel uses. Many researchers have suggested that chitosan nanoparticles (CS-NPs) and their derivatives are one of the best nanomaterials for delivering antibacterial activity. CS-NPs have a broad spectrum of antibacterial activity, but they manifest different inhibitory efficacy against gram-negative (G−) and gram-positive (G+) bacterial species. The mechanism of antibacterial action is an intricate process that varies between G− and G+ bacteria as a result of the differences in cell wall and cell membrane chemistry. In previous studies, greater antibacterial activity was more evident against G− bacteria than G+ bacteria, whereas in some studies G+ bacteria were more sensitive. Researchers predicted that the varied responses of bacteria are caused by the mixed hydrophilicity and negative charge distribution on the bacterial surface. Moreover, its activity depends on a number of variables including bacterial target (i.e., G− or G+ bacteria) and bacterial growth, as well as its concentration, pH, zeta-potential, molecular weight, and degree of acetylation. Therefore, this review examines current research on the mechanisms and factors affecting antibacterial activity, and application of CS-NPs specifically against animal and plant pathogenic bacteria. Full article
(This article belongs to the Section Biological Processes and Systems)
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41 pages, 16462 KiB  
Review
Supported Palladium Nanocatalysts: Recent Findings in Hydrogenation Reactions
by Marta A. Andrade and Luísa M. D. R. S. Martins
Processes 2020, 8(9), 1172; https://doi.org/10.3390/pr8091172 - 17 Sep 2020
Cited by 5 | Viewed by 3661
Abstract
Catalysis has witnessed a dramatic increase on the use of metallic nanoparticles in the last decade, opening endless opportunities in a wide range of research areas. As one of the most investigated catalysts in organic synthesis, palladium finds numerous applications being of significant [...] Read more.
Catalysis has witnessed a dramatic increase on the use of metallic nanoparticles in the last decade, opening endless opportunities in a wide range of research areas. As one of the most investigated catalysts in organic synthesis, palladium finds numerous applications being of significant relevance in industrial hydrogenation reactions. The immobilization of Pd nanoparticles in porous solid supports offers great advantages in heterogeneous catalysis, allowing control of the major factors that influence activity and selectivity. The present review deals with recent developments in the preparation and applications of immobilized Pd nanoparticles on solid supports as catalysts for hydrogenation reactions, aiming to give an insight on the key factors that contribute to enhanced activity and selectivity. The application of mesoporous silicas, carbonaceous materials, zeolites, and metal organic frameworks (MOFs) as supports for palladium nanoparticles is addressed. Full article
(This article belongs to the Special Issue Advances in Supported Nanoparticle Catalysts)
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18 pages, 944 KiB  
Article
Drag Effect of Carbon Emissions on the Urbanisation Process: Evidence from China’s Province Panel Data
by Jiajia Li, Jiangang Shi, Heng Li, Kaifeng Duan, Rui Zhang and Quanwei Xu
Processes 2020, 8(9), 1171; https://doi.org/10.3390/pr8091171 - 17 Sep 2020
Cited by 1 | Viewed by 2189
Abstract
This study attempts to measure the drag effect of carbon emissions on China’s economic growth by incorporating carbon emissions as an endogenous variable into an economic growth model and by relaxing the assumption that the size of the economy will remain unchanged. The [...] Read more.
This study attempts to measure the drag effect of carbon emissions on China’s economic growth by incorporating carbon emissions as an endogenous variable into an economic growth model and by relaxing the assumption that the size of the economy will remain unchanged. The drag effect of carbon emissions on the process of urbanisation is derived based on the intrinsic relationship between economic growth and urban development. Then, unit root and cointegration tests are performed using panel data from 30 provincial regions in Mainland China from 2003 to 2016 to prove and estimate the resistance caused by carbon emission in the process of urbanisation. Results show that the drag effect of carbon emission between 2003 and 2016 has a certain negative impact on the process of urbanisation in China. Due to the constraints of carbon emissions, the growth rate of China’s economic growth and urbanization level is 0.74% and 4.96% lower than that without constraints, respectively. Therefore, in the process of rapid urbanisation, formulating a reasonable carbon emission reduction strategy by the provincial government is conducive to the healthy and sustainable development of urbanisation. Full article
(This article belongs to the Special Issue Carbon Capture and Utilisation)
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18 pages, 7582 KiB  
Article
Optimization Design of a Two-Vane Pump for Wastewater Treatment Using Machine-Learning-Based Surrogate Modeling
by Sang-Bum Ma, Sung Kim and Jin-Hyuk Kim
Processes 2020, 8(9), 1170; https://doi.org/10.3390/pr8091170 - 17 Sep 2020
Cited by 12 | Viewed by 3859
Abstract
This paper deals with three-objective optimization, using machine-learning-based surrogate modeling to improve the hydraulic performances of a two-vane pump for wastewater treatment. For analyzing the internal flow field in the pump, steady Reynolds-averaged Navier-Stokes equations were solved with the shear stress transport turbulence [...] Read more.
This paper deals with three-objective optimization, using machine-learning-based surrogate modeling to improve the hydraulic performances of a two-vane pump for wastewater treatment. For analyzing the internal flow field in the pump, steady Reynolds-averaged Navier-Stokes equations were solved with the shear stress transport turbulence model as a turbulence closure model. The radial basis neural network model, which is an artificial neural network, was used as the surrogate model and trained to improve prediction accuracy. Three design variables related to the geometry of blade and volute were selected to optimize concurrently the objective functions with the total head and efficiency of the pump and size of the waste solids. The optimization results obtained by using the model showed highly accurate prediction values, and compared with the reference design, the optimum design provided improved hydraulic performances. Full article
(This article belongs to the Special Issue CFD Based Researches and Applications for Fluid Machinery and Fluid Device)
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