Next Issue
Volume 9, March
Previous Issue
Volume 9, January

Processes, Volume 9, Issue 2 (February 2021) – 218 articles

Cover Story (view full-size image): Microalgae and cyanobacteria have been proposed as alternative strategies to bioremediate agricultural waste while consuming carbon dioxide and producing valuable biomass. The current study assessed the potential of the microalga Scenedesmus sp. to remove nutrients from piggery wastewater and the influence of the microalga on the microbial consortia. This work demonstrated that the photosynthetic activity of microalgae can increase nutrient removal rates, minimizing both their environmental impact and health risks. Microalgae assimilated part of the N-NH4+ present in the media to produce biomass and did not convert it into N-NO3- as in traditional processes. View this paper
  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
Order results
Result details
Section
Select all
Export citation of selected articles as:
Article
Multi-Objective Optimization of Microstructure of Gravure Cell Based on Response Surface Method
Processes 2021, 9(2), 403; https://doi.org/10.3390/pr9020403 - 23 Feb 2021
Cited by 3 | Viewed by 729
Abstract
In order to improve the structural stiffness of the gravure cell structure in the solid printing process and realize a lightweight design, a multi-objective optimization design method was proposed to optimize the parameters of the direct laser engraving of the cell structure. In [...] Read more.
In order to improve the structural stiffness of the gravure cell structure in the solid printing process and realize a lightweight design, a multi-objective optimization design method was proposed to optimize the parameters of the direct laser engraving of the cell structure. In this paper, based on the characteristics of the cell structure and the analysis of the contact force, the ANSYS parametric design language (APDL) was used to conduct a finite element analysis on the microstructure of the regular hexagonal cell. We found that there is a certain optimization space. Then, a response surface (RSM) method optimization model, using a central composite design (CCD), was established to obtain, and then analyze, the sensitivity of each design variable to the objective functions. Finally, a multi-objective genetic algorithm (MOGA) was used to solve the model. The optimization results show that the maximum deformation was reduced by 44.4%, and the total volume was reduced by 46.3%. By comparing with the model before optimization, the rationality and effectiveness of this method were verified. This shows that the method can be effectively applied to the design optimization of gravure cell microstructure, and it provides theoretical support for new cell design. Full article
(This article belongs to the Section Advanced Digital and Other Processes)
Show Figures

Figure 1

Article
Process Improvements for Direct Reduced Iron Melting in the Electric Arc Furnace with Emphasis on Slag Operation
Processes 2021, 9(2), 402; https://doi.org/10.3390/pr9020402 - 23 Feb 2021
Cited by 4 | Viewed by 1169
Abstract
Steelmaking based on direct reduced iron (DRI, and its compacted derivative hot briquetted iron, HBI) is an anticipated important global alternative to current steel production based on FeOx reduction in blast furnaces due to its lower specific CO2 emission. The majority [...] Read more.
Steelmaking based on direct reduced iron (DRI, and its compacted derivative hot briquetted iron, HBI) is an anticipated important global alternative to current steel production based on FeOx reduction in blast furnaces due to its lower specific CO2 emission. The majority of DRI is melted and refined in the electric arc furnace with different process conditions compared to the melting of steel scrap due to its raw material composition being rather different. We provide data and analysis of slag composition of DRI charges vs. steel scrap charges for 16 industrial electric arc furnaces (EAFs). Suggestions for optimized slag operation and resulting process improvements of DRI melting in the EAF are given. A dynamic mass and energy model of the DRI melting in the EAF is introduced to illustrate the implications of the adapted slag operation on the EAF process with DRI charges. Full article
(This article belongs to the Section Materials Processes)
Show Figures

Figure 1

Article
Preservation of Antioxidant Properties of Endemic Dark Corn Using Solar Energy for Nixtamalization
Processes 2021, 9(2), 401; https://doi.org/10.3390/pr9020401 - 23 Feb 2021
Viewed by 698
Abstract
A comparative study of two corn nixtamalization processes is presented, one in the traditional way of the Michoacan region of Mexico, and the other using solar devices. The corn selected for the process was a nontransgenic endemic dark corn. For the nixtamalization process, [...] Read more.
A comparative study of two corn nixtamalization processes is presented, one in the traditional way of the Michoacan region of Mexico, and the other using solar devices. The corn selected for the process was a nontransgenic endemic dark corn. For the nixtamalization process, a solar concentration oven was used; this process using the solar device is simple and affordable for communities. For characterization, the properties of the antioxidant content of dark corn were analyzed for both processes, and the highest concentration of antioxidants between the two varieties of corn was obtained. The antioxidant capacity in the two varieties of black corn was quantified and determined, and the anthocyanin pigments were extracted with methanol. The total anthocyanin content (CAT) was evaluated by the pH difference method, and the antioxidant capacity by the DPPH method. In the solar nixtamalization process, a higher content of CAT anthocyanins and antioxidant capacity were obtained. Therefore, the solar energy process was proposed as a sustainable energy option, and we concluded that black corn nixtamalized with a solar oven had high antioxidant levels and could be used as a nutritious food. Full article
(This article belongs to the Collection Sustainable Food Processing Processes)
Show Figures

Figure 1

Article
Promotional Effects of Rare-Earth Praseodymium (Pr) Modification over MCM-41 for Methyl Mercaptan Catalytic Decomposition
Processes 2021, 9(2), 400; https://doi.org/10.3390/pr9020400 - 23 Feb 2021
Viewed by 692
Abstract
Praseodymium (Pr)-promoted MCM-41 catalyst was investigated for the catalytic decomposition of methyl mercaptan (CH3SH). Various characterization techniques, such as X-ray diffraction (XRD), N2 adsorption–desorption, temperature-programmed desorption of ammonia (NH3-TPD) and carbon dioxide (CO2-TPD), hydrogen temperature-programmed reduction [...] Read more.
Praseodymium (Pr)-promoted MCM-41 catalyst was investigated for the catalytic decomposition of methyl mercaptan (CH3SH). Various characterization techniques, such as X-ray diffraction (XRD), N2 adsorption–desorption, temperature-programmed desorption of ammonia (NH3-TPD) and carbon dioxide (CO2-TPD), hydrogen temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectrometer (XPS), were carried out to analyze the physicochemical properties of material. XPS characterization results showed that praseodymium was presented on the modified catalyst in the form of praseodymium oxide species, which can react with coke deposit to prolong the catalytic stability until 120 h. Meanwhile, the strong acid sites were proved to be the main active center over the 10% Pr/MCM-41 catalyst by NH3-TPD results during the catalytic elimination of methyl mercaptan. The possible reaction mechanism was proposed by analyzing the product distribution results. The final products were mainly small-molecule products, such as methane (CH4) and hydrogen sulfide (H2S). Dimethyl sulfide (CH3SCH3) was a reaction intermediate during the reaction. Therefore, this work contributes to the understanding of the reaction process of catalytic decomposition methyl mercaptan and the design of anti-carbon deposition catalysts. Full article
Show Figures

Figure 1

Article
Modeling and Multi-Criteria Optimization of a Process for H2O2 Electrosynthesis
Processes 2021, 9(2), 399; https://doi.org/10.3390/pr9020399 - 23 Feb 2021
Cited by 2 | Viewed by 957
Abstract
This article introduces a novel laboratory-scale process for the electrochemical synthesis of hydrogen peroxide (H2O2). The process aims at an energy-efficient, decentralized production, and a mathematical optimization of it is presented. A dynamic, zero-dimensional mathematical model of the reactor [...] Read more.
This article introduces a novel laboratory-scale process for the electrochemical synthesis of hydrogen peroxide (H2O2). The process aims at an energy-efficient, decentralized production, and a mathematical optimization of it is presented. A dynamic, zero-dimensional mathematical model of the reactor is set up in Aspen custom modeler®. The proposed model constitutes a reasonable compromise between complexity and convergence. After thoroughly determining the reaction kinetics by adjustment to experimental data, the reactor unit is embedded in an Aspen Plus® flowsheet in order to investigate its interaction with other unit operations. The downstream contains another custom module for membrane distillation. Electricity appears as a resource in the process, and optimization shows that it reaches product purities of up to 3 wt.-%. Both the process optimization and the adjustment of the reaction kinetics are treated as multi-criteria optimization (MCO) problems. Full article
(This article belongs to the Special Issue Design and Optimization in Process Engineering)
Show Figures

Figure 1

Article
Solvent Extraction of Boric Acid: Comparison of Five Different Monohydric Alcohols and Equilibrium Modeling with Numerical Methods
Processes 2021, 9(2), 398; https://doi.org/10.3390/pr9020398 - 23 Feb 2021
Viewed by 1230
Abstract
Solvent extraction is one of the common methods for the recovery of boric acid (or boron) from aqueous solutions. A wide variety of different compounds including monohydric alcohols has been tested, and there is wide recognition that they are rather ineffective compared to [...] Read more.
Solvent extraction is one of the common methods for the recovery of boric acid (or boron) from aqueous solutions. A wide variety of different compounds including monohydric alcohols has been tested, and there is wide recognition that they are rather ineffective compared to other extractants such as diols. Nevertheless, monohydric alcohols find application in industrial processes, demonstrating their efficiency. The intention of this study is to clarify this discrepancy and to provide an overall picture of monohydric alcohols as an extractant for boric acid. Five different monohydric alcohols are the object of this study: n-octanol, 2-ethyl-1-hexanol, 2-butyl-1-octanol, 2-octanol and 3,7-dimethyl-3-octanol. A special focus of this work is the examination of the effect of the structure of the carbon chain and the effect of the composition of the aqueous phase on the extraction efficiency. As well as the extraction efficiency for boric acid, other important properties are examined such as the viscosity of the organic phase, the solubility of alcohols in the aqueous phase and the co-extraction of salts used as a salting-out agent (NaCl, Na2SO4, MgCl2, LiCl, LiNO3). Finally, a numerical algorithm is developed to calculate the relationship between the number of theoretical stages and the phase ratio at equilibrium for selected extraction systems. Full article
Show Figures

Figure 1

Article
Production of Lignocellulolytic Enzymes and Biomass of Trametes versicolor from Agro-Industrial Residues in a Novel Fixed-Bed Bioreactor with Natural Convection and Forced Aeration at Pilot Scale
Processes 2021, 9(2), 397; https://doi.org/10.3390/pr9020397 - 23 Feb 2021
Cited by 4 | Viewed by 818
Abstract
Solid-state fermentation requires the development of more efficient cultivation systems for its industrial application. The objective of this work was to evaluate the effect of aeration regime on the production of biomass and several lignocellulolytic enzymes (laccase, manganese peroxidase, endoxylanase, β-glucosidase, and total [...] Read more.
Solid-state fermentation requires the development of more efficient cultivation systems for its industrial application. The objective of this work was to evaluate the effect of aeration regime on the production of biomass and several lignocellulolytic enzymes (laccase, manganese peroxidase, endoxylanase, β-glucosidase, and total cellulases) by Trametes versicolor in a novel fixed-bed solid-state pilot-scale bioreactor. Three regimes were assessed: natural convection, low aeration level (10 min every 6 h at 10 L/h air flowrate), and high aeration level (1 h every 6 h at 10 L/h air flowrate). The mushroom was grown on a medium based on lignocellulosic residues. The design of the bioreactor, as well as the control of aeration, humidity, and temperature of the beds, allowed T. versicolor to grow properly on the medium, reaching a maximum biomass production of 204.7 mg/g dry solid (ds). The influence that aeration regime had on the production of lignocellulolytic enzymes was determined. Low level of forced aeration favored obtaining the highest titers of laccase (6.37 U/g ds) compared to natural convection and high aeration level. The greatest lignin degradation was also verified for low aeration regime. For the first time, pilot scale cultivation of T. versicolor was reported in a fixed-bed bioreactor. Full article
(This article belongs to the Special Issue Novel Processes for Development of Fermentation-Based Products)
Show Figures

Graphical abstract

Article
Vermicomposting Process to Endosulfan Lactone Removal in Solid Substrate Using Eisenia fetida
Processes 2021, 9(2), 396; https://doi.org/10.3390/pr9020396 - 22 Feb 2021
Viewed by 674
Abstract
Pesticide by-products found in soil are usually more toxic and persistent than the pesticides themselves. For example, Endosulfan lactone (EL) (a by-product of the organochloride pesticide endosulfan). EL is created by the enzymatic activity (and related oxidative processes) of microorganisms in the soil. [...] Read more.
Pesticide by-products found in soil are usually more toxic and persistent than the pesticides themselves. For example, Endosulfan lactone (EL) (a by-product of the organochloride pesticide endosulfan). EL is created by the enzymatic activity (and related oxidative processes) of microorganisms in the soil. A sustainable method of EL removal is the introduction of Eisenia fetida earthworm. In this paper, it will be demonstrated the impact of vermicomposting process related to Eisenia fetida earthworm on EL by measuring initial and final concentrations of the compound and overall enzymatic activity in sterile and non-sterile solid substrate over 56 days. As a baseline, it be observed there were higher EL removals in non-sterile solid substrate (90.86%) at day 5 than in sterile solid substrate (83.86%) at day 14. In samples with Eisenia fetida, the presence of EL in non-sterile solid substrate was 36%, however in sterile solid substrate it was only 18% at day 1 and 7, with a maximum enzyme activity of 0.4659 mmol/mg protein per min at day 7. The evidence found in this study suggests that EL removal in a non-sterile solid substrate is higher when a vermicomposting is present and that the influence of microorganisms from the solid substrate with the earthworm, increases removal. Full article
(This article belongs to the Special Issue Bioremediation Processes of Contaminated Soil and Sediments)
Show Figures

Graphical abstract

Article
Research on Double-Stage and Multi-Stage Capacitive Deionization Absorption Air-Conditioning System
Processes 2021, 9(2), 395; https://doi.org/10.3390/pr9020395 - 22 Feb 2021
Viewed by 590
Abstract
An absorption air-conditioning system is a good choice for green buildings. It has the superiority in the utilization of renewable energy and the refrigerant is environment-friendly. However, the performance of the traditional absorption system has been restricted by the energy waste in the [...] Read more.
An absorption air-conditioning system is a good choice for green buildings. It has the superiority in the utilization of renewable energy and the refrigerant is environment-friendly. However, the performance of the traditional absorption system has been restricted by the energy waste in the thermal regeneration process. Capacitive deionization (CDI) regeneration is proposed as a potential method to improve system efficiency. In the new method-based air-conditioning system, strong absorbent solutions and pure water are acquired with the joint work of two CDI units. Nevertheless, the practical CDI device is composed of a lot of CDI units, which is quite different from the theoretical model. To reveal the performance of multiple CDI units, the model of the double/multi-stage CDI system has been developed. Analysis has been made to expose the influence of some key parameters. The results show the double-stage system has better performance than the single-stage system under certain conditions. The coefficient of performance (COP) could exceed 4.5, which is higher than the traditional thermal energy-driven system, or even as competitive as the vapor compression system. More stages with proper voltage distribution better the performance. It also provides the optimization method for the multi-stage CDI system. Full article
Show Figures

Figure 1

Review
The EU Training Network for Resource Recovery through Enhanced Landfill Mining—A Review
Processes 2021, 9(2), 394; https://doi.org/10.3390/pr9020394 - 22 Feb 2021
Cited by 7 | Viewed by 1616
Abstract
The “European Union Training Network for Resource Recovery Through Enhanced Landfill Mining (NEW-MINE)” was a European research project conducted between 2016 and 2020 to investigate the exploration of and resource recovery from landfills as well as the processing of the excavated waste and [...] Read more.
The “European Union Training Network for Resource Recovery Through Enhanced Landfill Mining (NEW-MINE)” was a European research project conducted between 2016 and 2020 to investigate the exploration of and resource recovery from landfills as well as the processing of the excavated waste and the valorization of the obtained waste fractions using thermochemical processes. This project yielded more than 40 publications ranging from geophysics via mechanical process engineering to ceramics, which have not yet been discussed coherently in a review publication. This article summarizes and links the NEW-MINE publications and discusses their practical applicability in waste management systems. Within the NEW-MINE project in a first step concentrates of specific materials (e.g., metals, combustibles, inert materials) were produced which might be used as secondary raw materials. In a second step, recycled products (e.g., inorganic polymers, functional glass-ceramics) were produced from these concentrates at the lab scale. However, even if secondary raw materials or recycled products could be produced at a large scale, it remains unclear if they can compete with primary raw materials or products from primary raw materials. Given the ambitions of transition towards a more circular economy, economic incentives are required to make secondary raw materials or recycled products from enhanced landfill mining (ELFM) competitive in the market. Full article
(This article belongs to the Special Issue Advanced Technology of Waste Treatment)
Show Figures

Figure 1

Article
A Methodology for Industrial Water Footprint Assessment Using Energy-Water-Carbon Nexus
Processes 2021, 9(2), 393; https://doi.org/10.3390/pr9020393 - 22 Feb 2021
Cited by 5 | Viewed by 1556
Abstract
Recent national government policy in Ireland proposes a radical transformation of the energy sector and a large reduction in CO2 emissions by 2050. Water and energy form the water–energy nexus, with water being an essential component in energy production. However, the connection [...] Read more.
Recent national government policy in Ireland proposes a radical transformation of the energy sector and a large reduction in CO2 emissions by 2050. Water and energy form the water–energy nexus, with water being an essential component in energy production. However, the connection between the production of energy and water is rarely made. In particular, the end-user processes are generally excluded because they occur outside the water industry. The present study includes two simple approaches for industrial sites to calculate their carbon footprint in the water sector. The assessment of the milk powder manufacturing using both approaches indicates that the combined emission factor of the water supply and treatment is approximately 1.28 kg CO2 m−3 of water. The dairy production among steel, textile, and paper industries appears to be the most carbon-emitting industry. However, the results show that the carbon intensity of the water supply and treatment can be minimized by the integration of renewable energy sources for the onsite heat/steam and electricity generation. The uniqueness of our approaches compared to calculations illustrated by the ecoinvent and other governmental databases is its simplicity and a focus on the main energy consuming manufacturing steps in the entire industrial process. We believe that the management of water and energy resources will be more efficient when “active water citizens” raise environmental awareness through promoting measures regarding data monitoring and collection, observed leaks and damages, dissimilation and exchange of information on sustainable water stewardship to public and various industrial stakeholders. Full article
(This article belongs to the Special Issue Sustainable Manufacturing and LCA Tools for Industrial Sectors)
Show Figures

Figure 1

Article
Fluorescence Enhancement on Silver-Plated Plasma Micro-Nanostructured 3D Polymeric Microarray Substrates for Multiplex Mycotoxin Detection
Processes 2021, 9(2), 392; https://doi.org/10.3390/pr9020392 - 21 Feb 2021
Cited by 2 | Viewed by 786
Abstract
Oxygen plasma micro-nanostructured poly(methyl methacrylate) (PMMA) slides were modified through silver microparticle deposition to create microarray substrates that enhance the emitted fluorescence intensity. Silver deposition relied on a commercially available reagent and was completed in two 30-min incubation cycles of the substrate with [...] Read more.
Oxygen plasma micro-nanostructured poly(methyl methacrylate) (PMMA) slides were modified through silver microparticle deposition to create microarray substrates that enhance the emitted fluorescence intensity. Silver deposition relied on a commercially available reagent and was completed in two 30-min incubation cycles of the substrate with the reagent. The fluorescence enhancement achieved using these substrates over flat PMMA slides was determined through the development of a microarray for the multiplexed detection of four mycotoxins, aflatoxin B1, ochratoxin A, fumonisin B1, and deoxynivalenol. It was shown that the implementation of silver-plated oxygen plasma micro-nanotextured PMMA substrates increased the signals obtained for aflatoxin B1 and ochratoxin A by approximately 2.8 times, 5.6 times for deoxynivalenol, and 16-times for fumonisin B1, compared to flat PMMA substrates. Most notably, this signal increase was not accompanied by a significant increase in the non-specific signal. In addition, the spot repeatability both across a single slide as well as between different slides was high, with coefficients of variation lower than 12%. The slides were also stable for at least three months, thus offering a microarray substrate with improved properties compared to standard glass slides, regarding both the absolute spot fluorescence intensity and between spots repeatability. Full article
(This article belongs to the Special Issue Micro and Nanotechnology: Application in Surface Modification)
Show Figures

Figure 1

Article
In Situ Modification of Activated Carbons by Oleic Acid under Microwave Heating to Improve Adsorptive Removal of Naphthalene in Aqueous Solutions
Processes 2021, 9(2), 391; https://doi.org/10.3390/pr9020391 - 21 Feb 2021
Cited by 4 | Viewed by 801
Abstract
This study aimed to improve the adsorption capacity of activated carbon (AC) towards naphthalene (NAP) in aqueous solutions. Starch-based AC (SAC) and pulverized coal-based AC (PCAC) were prepared in a one-pot procedure by activation with oleic acid and KOH under microwave heating. Brunauer–Emmett–Teller [...] Read more.
This study aimed to improve the adsorption capacity of activated carbon (AC) towards naphthalene (NAP) in aqueous solutions. Starch-based AC (SAC) and pulverized coal-based AC (PCAC) were prepared in a one-pot procedure by activation with oleic acid and KOH under microwave heating. Brunauer–Emmett–Teller (BET) specific surface areas reached 725.0 and 912.9 m2/g for in situ modified SAC (O-SAC1) and PCAC (O-PCAC1), respectively. π–π bond, H-bond, and hydrophobic effects were directly involved in the NAP adsorption process. Batch adsorption data were well fitted by pseudo-second order kinetics and the Freundlich isotherm model. As compared to ACs prepared with only KOH activation, NAP adsorption capacities of PCAC and SAC prepared by the one-pot method increased by 16.9% and 13.7%, respectively. Influences of varying factors were investigated in column adsorption of NAP using O-SAC1 and O-PCAC1. Based on breakthrough curves analysis, the larger column height (H), lower flow rate (Q0), and lower initial concentration (C0) resulted in the longer breakthrough and exhaustion times in both cases. Specifically, we concluded that O-PCAC1 exhibits better adsorption capacity than O-SAC1 in the given conditions. The optimized operating parameters were 1 cm (H), 1 mL/min (Q0) and 30 mg/L (C0). Finally, column adsorption data could be well fitted by the Thomas model. Full article
(This article belongs to the Special Issue Activated Carbon in Contaminant Removal)
Show Figures

Figure 1

Article
Effective Desulfurization and Alumina Digestion of High-Sulfur Bauxite by New Roasting Process with Conveying Bed
Processes 2021, 9(2), 390; https://doi.org/10.3390/pr9020390 - 20 Feb 2021
Cited by 3 | Viewed by 732
Abstract
A new roasting process with a conveying bed was constructed and used to remove sulfur of high-sulfur bauxite. Roasting temperature, phase transformation, microcrystal, specific surface area of high-sulfur bauxite, and the mechanism of the reaction during the roasting process were analyzed. The digestion [...] Read more.
A new roasting process with a conveying bed was constructed and used to remove sulfur of high-sulfur bauxite. Roasting temperature, phase transformation, microcrystal, specific surface area of high-sulfur bauxite, and the mechanism of the reaction during the roasting process were analyzed. The digestion properties of roasted bauxite were also investigated. The results showed that the sulfur in high-sulfur bauxite can be efficiently removed by roasting in the conveying bed at 520–720 °C for 2 s. Major reactions of high-sulfur bauxite during roasting were the dehydration of minerals, desulfurization of pyrite, sulfation of SO2, and decomposition of sulfate. The rate of mineral dehydration reaction was significantly slower than that of the desulfurization reaction. The specific surface area of roasted ore greatly increased, and the microcrystal of Al-O mineral was refined, which was conducive to Al2O3 digestion. The mass fraction of sulfide sulfur in high-sulfur bauxite was reduced from 1.20% to 0.01%, and the relative digestibility of alumina reached more than 99% when roasting at 600 °C for 2 s. This paper provides revelations and instructions for the process development and application of high-sulfur bauxite. Full article
Show Figures

Figure 1

Article
Modular Feedback Control of Networked Systems by Clustering: A Drinking Water Network Case Study
Processes 2021, 9(2), 389; https://doi.org/10.3390/pr9020389 - 20 Feb 2021
Cited by 4 | Viewed by 809
Abstract
This article presents a method based on linear matrix inequalities (LMIs) for designing a modular feedback control law, whose synthesis guarantees the system stability, while switching to different network topologies. Such stability is achieved by means of a common Lyapunov function to all [...] Read more.
This article presents a method based on linear matrix inequalities (LMIs) for designing a modular feedback control law, whose synthesis guarantees the system stability, while switching to different network topologies. Such stability is achieved by means of a common Lyapunov function to all network admissible configurations. Several mechanisms to relieve the computational burden of this methodology in large-scale systems are also presented. To assess its applicability, the modular controller is tested on a real case study, namely the Barcelona drinking water network (DWN), and its performance is compared with that of other control strategies, showing the effectiveness of the proposed approach. Full article
(This article belongs to the Special Issue Optimization and Control of Integrated Water Systems)
Show Figures

Figure 1

Review
Recent Developments in Carbon Quantum Dots: Properties, Fabrication Techniques, and Bio-Applications
Processes 2021, 9(2), 388; https://doi.org/10.3390/pr9020388 - 20 Feb 2021
Cited by 17 | Viewed by 2228
Abstract
Carbon dots have gained tremendous interest attributable to their unique features. Two approaches are involved in the fabrication of quantum dots (Top-down and Bottom-up). Most of the synthesis methods are usually multistep, required harsh conditions, and costly carbon sources that may have a [...] Read more.
Carbon dots have gained tremendous interest attributable to their unique features. Two approaches are involved in the fabrication of quantum dots (Top-down and Bottom-up). Most of the synthesis methods are usually multistep, required harsh conditions, and costly carbon sources that may have a toxic effect, therefore green synthesis is more preferable. Herein, the current review presents the green synthesis of carbon quantum dots (CQDs) and graphene quantum dots (GQDs) that having a wide range of potential applications in bio-sensing, cellular imaging, and drug delivery. However, some drawbacks and limitations are still unclear. Other biomedical and biotechnological applications are also highlighted. Full article
Show Figures

Figure 1

Article
A Novel Hybrid Model Based on an Improved Seagull Optimization Algorithm for Short-Term Wind Speed Forecasting
Processes 2021, 9(2), 387; https://doi.org/10.3390/pr9020387 - 20 Feb 2021
Cited by 10 | Viewed by 1498
Abstract
Wind energy is a clean energy source and is receiving widespread attention. Improving the operating efficiency and economic benefits of wind power generation systems depends on more accurate short-term wind speed predictions. In this study, a new hybrid model for short-term wind speed [...] Read more.
Wind energy is a clean energy source and is receiving widespread attention. Improving the operating efficiency and economic benefits of wind power generation systems depends on more accurate short-term wind speed predictions. In this study, a new hybrid model for short-term wind speed forecasting is proposed. The model combines variational modal decomposition (VMD), the proposed improved seagull optimization algorithm (ISOA) and the kernel extreme learning machine (KELM) network. The model adopts a hybrid modeling strategy: firstly, VMD decomposition is used to decompose the wind speed time series into several wind speed subseries. Secondly, KELM optimized by ISOA is used to predict each decomposed subseries. The ISOA technique is employed to accurately find the best parameters in each KELM network such that the predictability of a single KELM model can be enhanced. Finally, the prediction results of the wind speed sublayer are summarized to obtain the original wind speed. This hybrid model effectively characterizes the nonlinear and nonstationary characteristics of wind speed and greatly improves the forecasting performance. The experiment results demonstrate that: (1) the proposed VMD-ISOA-KELM model obtains the best performance for the application of three different prediction horizons compared with the other classic individual models, and (2) the proposed hybrid model combining the VMD technique and ISOA optimization algorithm performs better than models using other data preprocessing techniques. Full article
Show Figures

Figure 1

Article
Synthesis and Characterization of Magnetic Xerogel Monolith as an Adsorbent for As(V) Removal from Groundwater
Processes 2021, 9(2), 386; https://doi.org/10.3390/pr9020386 - 20 Feb 2021
Cited by 4 | Viewed by 633
Abstract
Arsenic contamination of groundwater is still a global problem due to the toxicity at low dose on human health confirmed by epidemiological studies. Magnetic xerogel monoliths (MXs) were synthesized by the sol-gel polymerization using resorcinol, formaldehyde, alkaline catalyst and magnetite. The varying molar [...] Read more.
Arsenic contamination of groundwater is still a global problem due to the toxicity at low dose on human health confirmed by epidemiological studies. Magnetic xerogel monoliths (MXs) were synthesized by the sol-gel polymerization using resorcinol, formaldehyde, alkaline catalyst and magnetite. The varying molar ratios of magnetite and resorcinol (M/R) in the gel were evaluated for As(V) removal from groundwater. The surface chemistry, structure and morphology of MXs related to arsenic adsorption were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and point of zero charge. Batch adsorption experiments were carried out to investigate the effects of Fe contents, initial pH and adsorbent dose on As(V) removal performance. The MXs with molar ratio of M/R at 0.15 gave the maximum As(V) adsorption capacity and removal with values of 62.8 µg/g and 86.7%, respectively. The adsorption data were well described by the Elovich equation of the kinetic model and the Freundlich isotherm. The thermodynamic studies demonstrated that the adsorption process was endothermic and spontaneous in nature. MXs showed to be a good alternative for As(V) removal from groundwater and achieving the efficient desorption, and thus fulfilled the Mexican standard for drinking water. Full article
Show Figures

Figure 1

Article
Thermal Control Processes by Deterministic and Network-Based Models for Energy Use and Control Accuracy in a Building Space
Processes 2021, 9(2), 385; https://doi.org/10.3390/pr9020385 - 20 Feb 2021
Cited by 1 | Viewed by 469
Abstract
Various control approaches for building thermal controls have been studied to improve the energy use which determines a large part of the spatial thermal quality. This research compares the performance of deterministic models and a network-based model to examine the aspects of both [...] Read more.
Various control approaches for building thermal controls have been studied to improve the energy use which determines a large part of the spatial thermal quality. This research compares the performance of deterministic models and a network-based model to examine the aspects of both energy consumption and thermal comfort. The single-switch deterministic model immediately responds to indoor thermal conditions, but the network-based model sends better-fit signals derived from learned data reflecting seven different climate conditions. As a result, the network-based model improves the thermal comfort level by about 6.1% to 9.4% and the energy efficiency by about 1.8% to 39.5% as compared to a thermostat and a fuzzy model. In the case of a specific weather condition, it can be confirmed that the process of finding efficient control values based on the network-based learning algorithm is more efficient than the conventional deterministic models. Full article
(This article belongs to the Special Issue Various Sustainable Energy Technologies in Buildings)
Show Figures

Figure 1

Article
Effect of Choline-Based Deep Eutectic Solvent Pretreatment on the Structure of Cellulose and Lignin in Bagasse
Processes 2021, 9(2), 384; https://doi.org/10.3390/pr9020384 - 19 Feb 2021
Cited by 13 | Viewed by 1359
Abstract
Deep eutectic solvents (DESs) is a newly developed green solvent with low cost, easy preparation and regeneration. Because of its excellent solubility and swelling effect in lignocellulose, it has received widespread attention and recognition. In this study, choline-based deep eutectic solvents (DESs)—choline chloride-urea [...] Read more.
Deep eutectic solvents (DESs) is a newly developed green solvent with low cost, easy preparation and regeneration. Because of its excellent solubility and swelling effect in lignocellulose, it has received widespread attention and recognition. In this study, choline-based deep eutectic solvents (DESs)—choline chloride-urea (CC-U), choline chloride-ethylene glycol (CC-EG), choline chloride-glycerol (CC-G), choline chloride-lactic acid (CC-LA), and choline chloride-oxalic acid (CC-OA)—were used to extract and separate bagasse. The effects of hydrogen bond donors on lignin separation and the fiber and lignin structure were investigated. All five DESs could dissolve lignin from bagasse; acidic DESs exhibited higher solubility than basic DESs. CC-OA effectively separated lignin and hemicellulose. CC-LA showed weaker lignin separation ability than CC-OA. CC-G, CC-EG, and CC-U were more inclined to selectively separate lignin than hemicellulose. The crystalline cellulose II structure was retained after DES pretreatment. Acidic DESs effectively improved the crystallinity of bagasse fiber; the crystallinities for CC-OA and CC-LA pretreatment were 62.26% and 61.65%, respectively. The lignin dissolved in DES was mainly syringyl lignin. The lignin dissolved in CC-U, CC-LA, and CC-OA contained a small amount of guaiacyl lignin. Full article
Show Figures

Figure 1

Article
PPO-Inhibiting Herbicides and Structurally Relevant Schiff Bases: Evaluation of Inhibitory Activities against Human Protoporphyrinogen Oxidase
Processes 2021, 9(2), 383; https://doi.org/10.3390/pr9020383 - 19 Feb 2021
Viewed by 877
Abstract
The study of human protoporphyrinogen oxidase (hPPO) inhibition can contribute significantly to a better understanding of some pathogeneses (e.g., porphyria, herbicide exposure) and the development of anticancer agents. Therefore, we prepared new potential inhibitors with Schiff base structural motifs (2-hydroxybenzaldehyde-based Schiff bases 9 [...] Read more.
The study of human protoporphyrinogen oxidase (hPPO) inhibition can contribute significantly to a better understanding of some pathogeneses (e.g., porphyria, herbicide exposure) and the development of anticancer agents. Therefore, we prepared new potential inhibitors with Schiff base structural motifs (2-hydroxybenzaldehyde-based Schiff bases 913 and chromanone derivatives 1719) as structurally relevant to PPO herbicides. The inhibitory activities (represented by the half maximal inhibitory concentration (IC50) values) and enzymatic interactions (represented by the hPPO melting temperatures) of these synthetic compounds and commercial PPO herbicides used against hPPO were studied by a protoporphyrin IX fluorescence assay. In the case of PPO herbicides, significant hPPO inhibition and changes in melting temperature were observed for oxyfluorten, oxadiazon, lactofen, butafenacil, saflufenacil, oxadiargyl, chlornitrofen, and especially fomesafen. Nevertheless, the prepared compounds did not display significant inhibitory activity or changes in the hPPO melting temperature. However, a designed model of hPPO inhibitors based on the determined IC50 values and a docking study (by using AutoDock) found important parts of the herbicide structural motif for hPPO inhibition. This model could be used to better predict PPO herbicidal toxicity and improve the design of synthetic inhibitors. Full article
(This article belongs to the Special Issue Advances in Anticancer Agents)
Show Figures

Figure 1

Review
Ultrafiltration Method for Plasma Protein Binding Studies and Its Limitations
Processes 2021, 9(2), 382; https://doi.org/10.3390/pr9020382 - 19 Feb 2021
Cited by 7 | Viewed by 1071
Abstract
Plasma protein binding plays a critical role in drug therapy, being a key part in the characterization of any compound. Among other methods, this process is largely studied by ultrafiltration based on its advantages. However, the method also has some limitations that could [...] Read more.
Plasma protein binding plays a critical role in drug therapy, being a key part in the characterization of any compound. Among other methods, this process is largely studied by ultrafiltration based on its advantages. However, the method also has some limitations that could negatively influence the experimental results. The aim of this study was to underline key aspects regarding the limitations of the ultrafiltration method, and the potential ways to overcome them. The main limitations are given by the non-specific binding of the substances, the effect of the volume ratio obtained, and the need of a rigorous control of the experimental conditions, especially pH and temperature. This review presents a variety of methods that can hypothetically reduce the limitations, and concludes that ultrafiltration remains a reliable method for the study of protein binding. However, the methodology of the study should be carefully chosen. Full article
Case Report
Innovative Processes in Managing an Enterprise from the Energy and Food Sector in the Era of Industry 4.0
Processes 2021, 9(2), 381; https://doi.org/10.3390/pr9020381 - 19 Feb 2021
Cited by 24 | Viewed by 2522
Abstract
The paper analyzes issues related to production processes in learning organizations using innovative solutions based on the Industry 4.0 paradigm. This study was realized by surveys and observation of companies operating in the energy and food sectors. These are sectors that in recent [...] Read more.
The paper analyzes issues related to production processes in learning organizations using innovative solutions based on the Industry 4.0 paradigm. This study was realized by surveys and observation of companies operating in the energy and food sectors. These are sectors that in recent years have started to intensively implement innovative solutions and are undergoing a transformation towards an intelligent (digital) enterprise, which uses virtual reality, supported by effectively controlling the non-player characters (NPCs). The presented examples can be inspiration for chief executive officer (CEOs), chief operating officers (COOs), and chief information officers (CIOs), the people managing companies for investment in innovative solutions. The implementation of Industry 4.0 solutions, as well as new machines design according state-of-the-art achievements of mechanical engineering rules, will allow companies to implement new products, achieve better results (e.g., more products with lower production cost), increase operational efficiency (e.g., lower energy and water consumption), and meet environmental requirements (e.g., reduce CO2 emission, introduce zero-emission energy production). Full article
Show Figures

Figure 1

Article
The Effectiveness of Different Household Storage Strategies and Plant-Based Preservatives for Dehulled and Sun-Dried Breadfruit Seeds
Processes 2021, 9(2), 380; https://doi.org/10.3390/pr9020380 - 19 Feb 2021
Cited by 1 | Viewed by 1059
Abstract
In a tropical rainforest environment, different storage strategies are often adopted in the preservation of primary processed food crops, such as maize, sorghum, etc., after drying and dehulling to increase shelf-life. For breadfruit seeds (Treculia Africana), the current challenge is identifying [...] Read more.
In a tropical rainforest environment, different storage strategies are often adopted in the preservation of primary processed food crops, such as maize, sorghum, etc., after drying and dehulling to increase shelf-life. For breadfruit seeds (Treculia Africana), the current challenge is identifying the most appropriate short-term storage and packaging methods that can retain the quality of stored products and extend shelf-life. In this regard, we compared the performance of a plastic container, a weaved silo bag and a locally developed silo bin for the short-term storage of parboiled, dehulled and dried breadfruit seeds treated with locally sourced and affordable alligator pepper (Zingiberaceaeaframomum melegueta) and bitter kola (garcinia) powder as preservatives. We show that the concentration of CO2 was lower in the silo bin treated with 150 g alligator pepper and higher in the silo bag-treated with 100 g bitter kola nut. A higher CO2 concentration resulted in limited oxygen availability, higher water vapor, and a higher heat release rate. Non-treated bag storage had the highest average mold count of 1.093 × 103 CFU/mL, while silo bin-stored breadfruit treated with 150 g of alligator pepper had the lowest mold count of 2.6 × 102 CFU/mL. The storage time and botanical treatments influenced both the crude protein and crude fiber content. Average insect infestations were low (0–4.5) in the silo bin with breadfruits treated with alligator pepper powder, as the seeds seemed to continue to desorb moisture in storage, unlike in other treatments. The obtained results revealed the high potential of alligator pepper (Zingiberaceaeaframomum melegueta) as a botanical insecticide in preventing insect infestation and mold growth in stored breadfruit instead of using synthetic insecticide. An aluminum silo bin with alligator pepper powder is recommended to store dried and dehulled breadfruit seeds as a baseline for other tropical crops. Full article
(This article belongs to the Special Issue Advances in Postharvest Process Systems)
Show Figures

Figure 1

Article
Antioxidant-Loaded Mucoadhesive Nanoparticles for Eye Drug Delivery: A New Strategy to Reduce Oxidative Stress
Processes 2021, 9(2), 379; https://doi.org/10.3390/pr9020379 - 19 Feb 2021
Cited by 5 | Viewed by 1159
Abstract
There are several approaches to treat ocular diseases, which can be invasive or non-invasive. Within the non-invasive, new pharmaceutical strategies based on nanotechnology and mucoadhesive polymers are emerging methodologies, which aim to reach an efficient treatment of eye diseases. The aim of this [...] Read more.
There are several approaches to treat ocular diseases, which can be invasive or non-invasive. Within the non-invasive, new pharmaceutical strategies based on nanotechnology and mucoadhesive polymers are emerging methodologies, which aim to reach an efficient treatment of eye diseases. The aim of this work was the development of novel chitosan/hyaluronic acid nanoparticle systems with mucoadhesive properties, intended to encapsulate antioxidant molecules (e.g., crocin) aiming to reduce eye oxidative stress and, consequently, ocular disease. An ultraviolet (UV) absorber molecule, actinoquinol, was also added to the nanoparticles, to further decrease oxidative stress. The developed nanoparticles were characterized and the results showed a mean particle size lower than 400 nm, polydispersity index of 0.220 ± 0.034, positive zeta potential, and high yield. The nanoparticles were also characterized in terms of pH, osmolality, and viscosity. Mucoadhesion studies involving the determination of zeta potential, viscosity, and tackiness, showed a strong interaction between the nanoparticles and mucin. In vitro release studies using synthetic membranes in Franz diffusion cells were conducted to unravel the drug release kinetic profile. Ex vitro studies using pig eye scleras in Franz diffusion cells were performed to evaluate the permeation of the nanoparticles. Furthermore, in vitro assays using the ARPE-19 (adult retinal pigment epithelium) cell line showed that the nanoparticles can efficiently decrease oxidative stress and showed low cytotoxicity. Thus, the developed chitosan/hyaluronic acid nanoparticles are a promising system for the delivery of antioxidants to the eye, by increasing their residence time and controlling their delivery. Full article
(This article belongs to the Special Issue Development and Characterization of Nanocarriers for Drugs)
Show Figures

Graphical abstract

Article
Early Warning of Internal Leakage in Heat Exchanger Network Based on Dynamic Mechanism Model and Long Short-Term Memory Method
Processes 2021, 9(2), 378; https://doi.org/10.3390/pr9020378 - 19 Feb 2021
Cited by 1 | Viewed by 851
Abstract
In the process of butadiene rubber production, internal leakage occurs in heat exchangers due to excessive pressure difference. It leads to the considerable flow of organic matters into the circulating water system. Since these organic matters are volatile and prone to explode in [...] Read more.
In the process of butadiene rubber production, internal leakage occurs in heat exchangers due to excessive pressure difference. It leads to the considerable flow of organic matters into the circulating water system. Since these organic matters are volatile and prone to explode in the cold water tower, internal leakage is potentially dangerous for the enterprise. To prevent this phenomenon, a novel intelligent early warning and risk assessment method (DYN-EW-QRA) is proposed in this paper by combining dynamic simulations (DYN), long short-term memory (LSTM), and quantitative risk assessment (QRA). First, an original internal leakage mechanism model of a heat exchanger network is designed and simulated by DYN to obtain datasets. Second, the potential relationships between variables that have a direct impact on the hazards of the accident are deeply learned by LSTM to predict the internal leakage trends. Finally, the QRA method is used to analyze the range and destructive power of potential hazards. The results show that DYN-EW-QRA method has excellent performance. Full article
(This article belongs to the Special Issue Learning for Process Optimization and Control)
Show Figures

Figure 1

Review
Evolution of Nitrogen-Based Alkylating Anticancer Agents
Processes 2021, 9(2), 377; https://doi.org/10.3390/pr9020377 - 19 Feb 2021
Cited by 7 | Viewed by 1594
Abstract
Despite the significant progress in anticancer drug development over recent years, there is a vital need for newer agents with unique, but still effective, mechanisms of action in order to treat the disease, particularly the highly aggressive and drug-resistant types. Alkylating agents, in [...] Read more.
Despite the significant progress in anticancer drug development over recent years, there is a vital need for newer agents with unique, but still effective, mechanisms of action in order to treat the disease, particularly the highly aggressive and drug-resistant types. Alkylating agents, in particular nitrogen-based alkylators, are commonly used to treat hematological and solid malignancies; they exert their antineoplastic effects at all phases of the cell cycle and prevent reproduction of tumor cells. Certain alkylating agents have been designed to be more lipophilic, enabling the compound to penetrate the cell and enhance its alkylating activity against tumors. This review details the evolution of currently available alkylating agents and their profiles, with a focus on nitrogen-based alkylating agents, as important anticancer therapy strategies. Full article
(This article belongs to the Special Issue Advances in Anticancer Agents)
Show Figures

Figure 1

Article
Chromatographic and Computational Screening of Lipophilicity and Pharmacokinetics of Newly Synthesized Betulin-1,4-quinone Hybrids
Processes 2021, 9(2), 376; https://doi.org/10.3390/pr9020376 - 19 Feb 2021
Cited by 4 | Viewed by 945
Abstract
Lipophilicity is one of the most important parameters determining the pharmacodynamic and pharmacokinetic properties, as well as the toxicity of many compounds. The subject of the research was to determine the lipophilicity of betulin-1,4-quinone hybrids using thin layer chromatography in reverse phase system [...] Read more.
Lipophilicity is one of the most important parameters determining the pharmacodynamic and pharmacokinetic properties, as well as the toxicity of many compounds. The subject of the research was to determine the lipophilicity of betulin-1,4-quinone hybrids using thin layer chromatography in reverse phase system and computer programs to calculate its theoretical models. The correlation between the experimental and theoretical values of lipophilicity was analyzed. Lipinski’s and Veber’s rules, as well as penetration through the blood–brain barrier were also determined using computer programs. For all of the analyzed values, a similarity analysis was performed. The dendrograms for the experimental and theoretical lipophilicity show that there is a correlation between them. However, the dendrograms for the experimental lipophilicity and pharmacokinetic parameters indicate that there is no correlation between the structure and the pharmacological properties. Hybrids exhibit a high biological activity against cancer cell lines, with a high level of NAD[P]H-quinone oxidoreductase (NQO1) protein. The enzymatic assay used has shown that these compounds are good NQO1 substrates, as evidenced by the increasing metabolic rates relative to that of streptonigrin. The similarity analysis has also shown that there is no correlation between lipophilicity and biological activity for the tested compounds. Full article
(This article belongs to the Special Issue Applications of Chromatography in Drug Analysis and Development)
Show Figures

Figure 1

Review
A Review on the Synthesis, Characterization, and Modeling of Polymer Grafting
Processes 2021, 9(2), 375; https://doi.org/10.3390/pr9020375 - 18 Feb 2021
Cited by 8 | Viewed by 1817
Abstract
A critical review on the synthesis, characterization, and modeling of polymer grafting is presented. Although the motivation stemmed from grafting synthetic polymers onto lignocellulosic biopolymers, a comprehensive overview is also provided on the chemical grafting, characterization, and processing of grafted materials of different [...] Read more.
A critical review on the synthesis, characterization, and modeling of polymer grafting is presented. Although the motivation stemmed from grafting synthetic polymers onto lignocellulosic biopolymers, a comprehensive overview is also provided on the chemical grafting, characterization, and processing of grafted materials of different types, including synthetic backbones. Although polymer grafting has been studied for many decades—and so has the modeling of polymer branching and crosslinking for that matter, thereby reaching a good level of understanding in order to describe existing branching/crosslinking systems—polymer grafting has remained behind in modeling efforts. Areas of opportunity for further study are suggested within this review. Full article
(This article belongs to the Special Issue Modeling and Simulation of Polymerization Processes)
Show Figures

Figure 1

Article
A Bioreactor Designed for Restricting Oversize of Aerobic Granular Sludge
Processes 2021, 9(2), 374; https://doi.org/10.3390/pr9020374 - 18 Feb 2021
Viewed by 1371
Abstract
Aerobic granular sludge (AGS) with oversized diameter commonly affects its stability and pollutant removal. In order to effectively restrict the particle size of AGS, a sequencing batch reactor (SBR) with a spiny aeration device was put forward. A conventional SBR (R1) and an [...] Read more.
Aerobic granular sludge (AGS) with oversized diameter commonly affects its stability and pollutant removal. In order to effectively restrict the particle size of AGS, a sequencing batch reactor (SBR) with a spiny aeration device was put forward. A conventional SBR (R1) and an SBR (R2) with the spiny aeration device treating tannery wastewater were compared in the laboratory. The result indicates that the size of the granular sludge from R2 was smaller than that from R1 with sludge granulation. The spines and air bubbles could effectively restrict the particle size of AGS by collision and abrasion. Nevertheless, there was no significant change in mixed liquor suspended solids (MLSS) and the sludge volume index (SVI) in either bioreactors. The removal (%) of chemical oxygen demand (COD) and ammonia nitrogen (NH4+-N) in these two bioreactors did not differ from each other greatly. The analysis of biological composition displays that the proportion of Proteobacteria decreased slightly in R2. The X-ray fluorescence (XRF) analysis revealed less accumulation of Fe and Ca in smaller granules. Furthermore, a pilot-scale SBR with a spiny aeration device was successfully utilized to restrict the diameter of granules at about 300 μm. Full article
(This article belongs to the Special Issue Bioreactor System: Design, Modeling and Continuous Production Process)
Show Figures

Figure 1

Previous Issue
Next Issue
Back to TopTop