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Processes, Volume 7, Issue 4 (April 2019)

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Cover Story (view full-size image) The anti-apoptotic Mcl1 (Myeloid cell leukemia 1) protein (belonging to the Bcl2 family) is known [...] Read more.
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Open AccessArticle
Phenomenological Over-Parameterization of the Triple-Fitting-Parameter Diffusion Models in Evaluation of Gas Diffusion in Coal
Processes 2019, 7(4), 241; https://doi.org/10.3390/pr7040241
Received: 22 March 2019 / Revised: 23 April 2019 / Accepted: 23 April 2019 / Published: 25 April 2019
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Abstract
Gas diffusivities of coal are not measured directly but are normally regressed by fitting mathematical diffusion models to fractional sorption data measured in sorption experiments. This paper firstly measured three fractional adsorption curves at various equilibrium pressures with the manometric method. The measured [...] Read more.
Gas diffusivities of coal are not measured directly but are normally regressed by fitting mathematical diffusion models to fractional sorption data measured in sorption experiments. This paper firstly measured three fractional adsorption curves at various equilibrium pressures with the manometric method. The measured fractional adsorption curves were then modeled with one single-fitting-parameter (SFP) model and three triple-fitting-parameter (TFP) models. The modeling results showed that the TFP models were phenomenologically over-parameterized due to the usage of three fitting parameters, which may be excessive for curve fitting. The phenomenological over-parameterization resulted in multiple pressure-dependences of gas diffusivity for the TFP models. The TFP models should thus be carefully used. On the other hand, the dual-fitting-parameter (DFP) models also have excellent performance in curve fitting and can produce interpretable modeling results. The DFP models can be used as an alternative to the TFP model in the future. Full article
(This article belongs to the Special Issue Dynamic Modeling and Control in Chemical and Energy Processes)
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Open AccessArticle
Exploring Plant Sesquiterpene Diversity by Generating Chemical Networks
Processes 2019, 7(4), 240; https://doi.org/10.3390/pr7040240
Received: 28 February 2019 / Revised: 6 April 2019 / Accepted: 11 April 2019 / Published: 25 April 2019
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Abstract
Plants produce a diverse portfolio of sesquiterpenes that are important in their response to herbivores and the interaction with other plants. Their biosynthesis from farnesyl diphosphate depends on the sesquiterpene synthases that admit different cyclizations and rearrangements to yield a blend of sesquiterpenes. [...] Read more.
Plants produce a diverse portfolio of sesquiterpenes that are important in their response to herbivores and the interaction with other plants. Their biosynthesis from farnesyl diphosphate depends on the sesquiterpene synthases that admit different cyclizations and rearrangements to yield a blend of sesquiterpenes. Here, we investigate to what extent sesquiterpene biosynthesis metabolic pathways can be reconstructed just from the knowledge of the final product and the reaction mechanisms catalyzed by sesquiterpene synthases. We use the software package MedØlDatschgerl (MØD) to generate chemical networks and to elucidate pathways contained in them. As examples, we successfully consider the reachability of the important plant sesquiterpenes β -caryophyllene, α -humulene, and β -farnesene. We also introduce a graph database to integrate the simulation results with experimental biological evidence for the selected predicted sesquiterpenes biosynthesis. Full article
(This article belongs to the Special Issue In Silico Metabolic Modeling and Engineering)
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Open AccessArticle
Screening and Optimization of Demulsifiers and Flocculants Based on ASP Flooding-Produced Water
Processes 2019, 7(4), 239; https://doi.org/10.3390/pr7040239
Received: 26 March 2019 / Revised: 16 April 2019 / Accepted: 18 April 2019 / Published: 25 April 2019
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Abstract
The water produced by alkaline–surfactant–polymer (ASP) flooding is difficult to treat due to the presence of residual chemicals. Therefore, research and development of efficient and low-cost methods for the treatment of ASP flooding produced water is necessary. Chemical destabilization is the most common [...] Read more.
The water produced by alkaline–surfactant–polymer (ASP) flooding is difficult to treat due to the presence of residual chemicals. Therefore, research and development of efficient and low-cost methods for the treatment of ASP flooding produced water is necessary. Chemical destabilization is the most common and effective way to treat the produced water. This paper describes an optimization method for demulsification and flocculation. Some demulsifiers and flocculants commonly used in oilfields were screened, compounded, and optimized. Since the effect of treatment using only demulsifier or flocculant to treat the produced water is often not enough to meet the reinjection standard, an orthogonal experiment was carried out to study the demulsification–flocculation method to treat produced water. Five main influencing factors of the oil concentration were investigated. Based on the results of the range analysis and the relationship between the five factors and oil concentration, the order of significant factors was found to be demulsifier dosage > flocculant dosage > settling time > stirring time > stirring intensity, and the optimal demulsification–flocculation treatment conditions were successfully optimized. Full article
(This article belongs to the Section Green Processes)
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Open AccessArticle
Hydrogen Production and Subsequent Adsorption/Desorption Process within a Modified Unitized Regenerative Fuel Cell
Processes 2019, 7(4), 238; https://doi.org/10.3390/pr7040238
Received: 22 March 2019 / Revised: 17 April 2019 / Accepted: 22 April 2019 / Published: 24 April 2019
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Abstract
For sustainable and incremental growth, mankind is adopting renewable sources of energy along with storage systems. Storing surplus renewable energy in the form of hydrogen is a viable solution to meet continuous energy demands. In this paper the concept of electrochemical hydrogen storage [...] Read more.
For sustainable and incremental growth, mankind is adopting renewable sources of energy along with storage systems. Storing surplus renewable energy in the form of hydrogen is a viable solution to meet continuous energy demands. In this paper the concept of electrochemical hydrogen storage in a solid multi-walled carbon nanotube (MWCNT) electrode integrated in a modified unitized regenerative fuel cell (URFC) is investigated. The method of solid electrode fabrication from MWCNT powder and egg white as an organic binder is disclosed. The electrochemical testing of a modified URFC with an integrated MWCNT-based hydrogen storage electrode is performed and reported. Galvanostatic charging and discharging was carried out and results analyzed to ascertain the electrochemical hydrogen storage capacity of the fabricated electrode. The electrochemical hydrogen storage capacity of the porous MWCNT electrode is found to be 2.47 wt%, which is comparable with commercially available AB5-based hydrogen storage canisters. The obtained results prove the technical feasibility of a modified URFC with an integrated MWCNT-based hydrogen storage electrode, which is the first of its kind. This is surelya step forward towards building a sustainable energy economy. Full article
(This article belongs to the Special Issue Hydrogen Production Technologies)
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Open AccessFeature PaperArticle
Static Light Scattering Monitoring and Kinetic Modeling of Polyacrylamide Hydrogel Synthesis
Processes 2019, 7(4), 237; https://doi.org/10.3390/pr7040237
Received: 15 March 2019 / Revised: 16 April 2019 / Accepted: 17 April 2019 / Published: 24 April 2019
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Abstract
A kinetic model describing aqueous acrylamide homopolymerization and copolymerization of acrylamide with methylene bisacrylamide, leading to hydrogel formation, is presented and applied in the simulation of these reaction processes. This modeling approach is based on population balances of generating functions and, besides the [...] Read more.
A kinetic model describing aqueous acrylamide homopolymerization and copolymerization of acrylamide with methylene bisacrylamide, leading to hydrogel formation, is presented and applied in the simulation of these reaction processes. This modeling approach is based on population balances of generating functions and, besides the crosslinking mechanisms inherent to network formation, other specific kinetic steps important in acrylamide polymerization (e.g., branching due to backbiting) are considered in the simulation tool developed. The synthesis of acrylamide polymers and hydrogels was performed at 26 °C and at 40 °C using two different initiation systems. The formation of such materials was monitored using in-line static light scattering (SLS), and the spatial inhomogeneity of the final hydrogels was also measured using this experimental technique. It is shown that the simulations are helpful in describing information provided by SLS in-line monitoring, namely in the early stages of polymerization with the transition from dilute to semi-dilute regime. Indeed, it finds a plausible match between the critical overlap polymer concentration and gelation, this later leading to the observed spatial heterogeneity of the hydrogels. Usefulness of the kinetic model for defining operation conditions (initial composition, semi-batch feed policies, chain transfer, etc.) in making the shift from gelation to the semi-dilute regime is discussed, and the extension of this approach to processes enabling a higher control of gelation (e.g., controlled radical polymerization) is also prospected. Full article
(This article belongs to the Special Issue Modeling, Simulation and Control of Chemical Processes)
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Open AccessArticle
VB1 Promoted Green Synthesis of Chalcones and Its Neuroprotection Potency Evaluation
Processes 2019, 7(4), 236; https://doi.org/10.3390/pr7040236
Received: 26 February 2019 / Revised: 15 April 2019 / Accepted: 15 April 2019 / Published: 24 April 2019
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Abstract
For the first time, thiamine hydrochloride (VB1) has been employed as a catalyst for the synthesis of chalcones by metal-free Claisen–Schmidt condensation. Such an environmentally benign approach has several advantages such as a wide range of functional groups tolerance, a high [...] Read more.
For the first time, thiamine hydrochloride (VB1) has been employed as a catalyst for the synthesis of chalcones by metal-free Claisen–Schmidt condensation. Such an environmentally benign approach has several advantages such as a wide range of functional groups tolerance, a high yield of products, and the recoverability of this catalyst. Moreover, this unprecedented methodology enables the synthesis of the pharmaceutically important molecule 2′,4′-dihydroxy-6′-methoxy-3′,5′-dimethylchalcone (3f) and its derivatives. Moreover, 3f and its derivatives were screened for their preliminary in vitro neuroprotective activity against oxygen-glucose deprivation/reoxygenation (OGD/R)-induced apoptosis in SH-SY5Y cell lines. Most of the compounds exhibited the neuroprotective activity, and one of the prepared chalcones (3s), which incorporates prenyl moiety, showed the most potency by decreasing the expression of cleaved caspase-3, cleaved caspase-9, Bax, and p53 protein. Full article
(This article belongs to the Section Materials Processes)
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Open AccessArticle
A Machine Learning-based Pipeline for the Classification of CTX-M in Metagenomics Samples
Processes 2019, 7(4), 235; https://doi.org/10.3390/pr7040235
Received: 16 February 2019 / Revised: 2 April 2019 / Accepted: 8 April 2019 / Published: 24 April 2019
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Abstract
Bacterial infections are a major global concern, since they can lead to public health problems. To address this issue, bioinformatics contributes extensively with the analysis and interpretation of in silico data by enabling to genetically characterize different individuals/strains, such as in bacteria. However, [...] Read more.
Bacterial infections are a major global concern, since they can lead to public health problems. To address this issue, bioinformatics contributes extensively with the analysis and interpretation of in silico data by enabling to genetically characterize different individuals/strains, such as in bacteria. However, the growing volume of metagenomic data requires new infrastructure, technologies, and methodologies that support the analysis and prediction of this information from a clinical point of view, as intended in this work. On the other hand, distributed computational environments allow the management of these large volumes of data, due to significant advances in processing architectures, such as multicore CPU (Central Process Unit) and GPGPU (General Propose Graphics Process Unit). For this purpose, we developed a bioinformatics workflow based on filtered metagenomic data with Duk tool. Data formatting was done through Emboss software and a prototype of a workflow. A pipeline was also designed and implemented in bash script based on machine learning. Further, Python 3 programming language was used to normalize the training data of the artificial neural network, which was implemented in the TensorFlow framework, and its behavior was visualized in TensorBoard. Finally, the values from the initial bioinformatics process and the data generated during the parameterization and optimization of the Artificial Neural Network are presented and validated based on the most optimal result for the identification of the CTX-M gene group. Full article
(This article belongs to the Special Issue Bioinformatics Applications Based On Machine Learning)
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Open AccessFeature PaperArticle
Dynamic Flowsheet Model Development and Sensitivity Analysis of a Continuous Pharmaceutical Tablet Manufacturing Process Using the Wet Granulation Route
Processes 2019, 7(4), 234; https://doi.org/10.3390/pr7040234
Received: 12 March 2019 / Revised: 5 April 2019 / Accepted: 15 April 2019 / Published: 24 April 2019
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Abstract
In view of growing interest and investment in continuous manufacturing, the development and utilization of mathematical model(s) of the manufacturing line is of prime importance. These models are essential for understanding the complex interplay between process-wide critical process parameters (CPPs) and critical quality [...] Read more.
In view of growing interest and investment in continuous manufacturing, the development and utilization of mathematical model(s) of the manufacturing line is of prime importance. These models are essential for understanding the complex interplay between process-wide critical process parameters (CPPs) and critical quality attributes (CQAs) beyond the individual process operations. In this work, a flowsheet model that is an approximate representation of the ConsiGma TM -25 line for continuous tablet manufacturing, including wet granulation, is developed. The manufacturing line involves various unit operations, i.e., feeders, blenders, a twin-screw wet granulator, a fluidized bed dryer, a mill, and a tablet press. The unit operations are simulated using various modeling approaches such as data-driven models, semi-empirical models, population balance models, and mechanistic models. Intermediate feeders, blenders, and transfer lines between the units are also simulated. The continuous process is simulated using the flowsheet model thus developed and case studies are provided to demonstrate its application for dynamic simulation. Finally, the flowsheet model is used to systematically identify critical process parameters (CPPs) that affect process responses of interest using global sensitivity analysis methods. Liquid feed rate to the granulator, and air temperature and drying time in the dryer are identified as CPPs affecting the tablet properties. Full article
(This article belongs to the Special Issue Model-Based Tools for Pharmaceutical Manufacturing Processes)
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Open AccessArticle
The Potential for a Pellet Plant to Become a Biorefinery
Processes 2019, 7(4), 233; https://doi.org/10.3390/pr7040233
Received: 29 March 2019 / Revised: 18 April 2019 / Accepted: 19 April 2019 / Published: 24 April 2019
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Abstract
The use of bioenergy has increased globally in recent years, as has the utilization of biomaterials for various new product solutions through various biorefinery concepts. In this study, we introduce the concept of using a mechanical dewatering press in combination with thermal drying [...] Read more.
The use of bioenergy has increased globally in recent years, as has the utilization of biomaterials for various new product solutions through various biorefinery concepts. In this study, we introduce the concept of using a mechanical dewatering press in combination with thermal drying in a pellet plant. The purpose of the study is to increase the understanding of the effects a mechanical dewatering press has in a pellet production chain and investigate whether a pellet plant could thus become a biorefinery. The evaluations in this study are based on industrial data and initial tests at the university. The results show that the concept of using the mechanical dewatering press together with a packed moving bed dryer reduces energy use by 50%, compared to using only a packed moving bed dryer. The press water could be used as a raw material for biogas, bioplastics, and biohydrogen. Hence, this study points out the possibilities of a pellet plant increasing the efficiency of the drying step, while moving towards becoming a biorefinery. Full article
(This article belongs to the Special Issue Sustainable Biorefinery Processes)
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Open AccessArticle
A Numerical Analysis of Pressure Pulsation Characteristics Induced by Unsteady Blood Flow in a Bileaflet Mechanical Heart Valve
Processes 2019, 7(4), 232; https://doi.org/10.3390/pr7040232
Received: 20 March 2019 / Revised: 13 April 2019 / Accepted: 18 April 2019 / Published: 24 April 2019
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Abstract
The leaflet vibration phenomenon in bileaflet mechanical heart valves (BMHVs) can cause complications such as hemolysis, leaflet damage, and valve fracture. One of the main reasons for leaflet vibration is the unsteady blood flow pressure pulsation induced by turbulent flow instabilities. In this [...] Read more.
The leaflet vibration phenomenon in bileaflet mechanical heart valves (BMHVs) can cause complications such as hemolysis, leaflet damage, and valve fracture. One of the main reasons for leaflet vibration is the unsteady blood flow pressure pulsation induced by turbulent flow instabilities. In this study, we performed numerical simulations of unsteady flow through a BMHV and observed pressure pulsation characteristics under different flow rates and leaflet fully opening angle conditions. The pressure pulsation coefficient and the low-Reynolds k-ω model in CFD (Computational Fluid Dynamics) software were employed to solve these problems. Results showed that the level of pressure pulsation was highly influenced by velocity distribution, and that the higher coefficient of pressure pulsation was associated with the lower flow velocity along the main flow direction. The influence of pressure pulsation near the trailing edges was much larger than the data obtained near the leading edges of the leaflets. In addition, considering the level of pressure pulsation and the flow uniformity, the recommended setting of leaflet fully opening angle was about 80°. Full article
(This article belongs to the Special Issue Smart Flow Control Processes in Micro Scale)
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Open AccessArticle
Characterization of the Primary Sludge from Pharmaceutical Industry Effluents and Final Disposition
Processes 2019, 7(4), 231; https://doi.org/10.3390/pr7040231
Received: 12 December 2018 / Revised: 25 January 2019 / Accepted: 4 February 2019 / Published: 24 April 2019
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Abstract
The generation of large volumes of waste by industrial processes has become an object of study because of the necessity to characterize the composition of residues in order to suggest appropriate treatments and to minimize adverse environmental impacts. We performed analyses of total [...] Read more.
The generation of large volumes of waste by industrial processes has become an object of study because of the necessity to characterize the composition of residues in order to suggest appropriate treatments and to minimize adverse environmental impacts. We performed analyses of total fixed and volatile solids, moisture, and chemical oxygen demand (COD). We found high organic matter content. We also measured physicochemical characteristics, including corrosivity, reactivity, and toxicity. Sewage sludge showed levels of chloride and sodium above the maximum allowed limits. These data suggest the potential for anaerobic digestion as a treatment option for sewage sludge and for its use as a biofertilizer. Full article
(This article belongs to the Special Issue Green Sustainable Chemical Processes)
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Open AccessFeature PaperReview
Modular Engineering of Biomass Degradation Pathways
Processes 2019, 7(4), 230; https://doi.org/10.3390/pr7040230
Received: 27 February 2019 / Revised: 12 April 2019 / Accepted: 15 April 2019 / Published: 23 April 2019
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Abstract
Production of fuels and chemicals from renewable lignocellulosic feedstocks is a promising alternative to petroleum-derived compounds. Due to the complexity of lignocellulosic feedstocks, microbial conversion of all potential substrates will require substantial metabolic engineering. Non-model microbes offer desirable physiological traits, but also increase [...] Read more.
Production of fuels and chemicals from renewable lignocellulosic feedstocks is a promising alternative to petroleum-derived compounds. Due to the complexity of lignocellulosic feedstocks, microbial conversion of all potential substrates will require substantial metabolic engineering. Non-model microbes offer desirable physiological traits, but also increase the difficulty of heterologous pathway engineering and optimization. The development of modular design principles that allow metabolic pathways to be used in a variety of novel microbes with minimal strain-specific optimization will enable the rapid construction of microbes for commercial production of biofuels and bioproducts. In this review, we discuss variability of lignocellulosic feedstocks, pathways for catabolism of lignocellulose-derived compounds, challenges to heterologous engineering of catabolic pathways, and opportunities to apply modular pathway design. Implementation of these approaches will simplify the process of modifying non-model microbes to convert diverse lignocellulosic feedstocks. Full article
(This article belongs to the Special Issue Principles of Modular Design and Control in Complex Systems)
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Open AccessFeature PaperArticle
Pelletization of Torrefied Wood Using a Proteinaceous Binder Developed from Hydrolyzed Specified Risk Materials
Processes 2019, 7(4), 229; https://doi.org/10.3390/pr7040229
Received: 21 March 2019 / Revised: 15 April 2019 / Accepted: 16 April 2019 / Published: 23 April 2019
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Abstract
Pressing issues such as a growing energy demand and the need for energy diversification, emission reduction, and environmental protection serve as motivation for the utilization of biomass for production of sustainable fuels. However, use of biomass is currently limited due to its high [...] Read more.
Pressing issues such as a growing energy demand and the need for energy diversification, emission reduction, and environmental protection serve as motivation for the utilization of biomass for production of sustainable fuels. However, use of biomass is currently limited due to its high moisture content, relatively low bulk and energy densities, and variability in shape and size, relative to fossil-based fuels such as coal. In recent years, a combination of thermochemical treatment (torrefaction) of biomass and subsequent pelletization has resulted in a renewable fuel that can potentially substitute for coal. However, production of torrefied wood pellets that satisfy fuel quality standards and other logistical requirements typically requires the use of an external binder. Here, we describe the development of a renewable binder from proteinaceous material recovered from specified risk materials (SRM), a negative-value byproduct from the rendering industry. Our binder was developed by co-reacting peptides recovered from hydrolyzed SRM with a polyamidoamine epichlorohydrin (PAE) resin, and then assessed through pelleting trials with a bench-scale continuous operating pelletizer. Torrefied wood pellets generated using peptides-PAE binder at 3% binder level satisfied ISO requirements for durability, higher heating value, and bulk density for TW2a type thermally-treated wood pellets. This proof-of-concept work demonstrates the potential of using an SRM-derived binder to improve the durability of torrefied wood pellets. Full article
(This article belongs to the Special Issue Renewable Polymers: Processing and Chemical Modifications)
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Open AccessArticle
The Effects of Aluminium- and Ferric-Based Chemical Phosphorus Removal on Activated Sludge Digestibility and Dewaterability
Processes 2019, 7(4), 228; https://doi.org/10.3390/pr7040228
Received: 6 April 2019 / Revised: 17 April 2019 / Accepted: 19 April 2019 / Published: 23 April 2019
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Abstract
The uses of Al3+ and Fe3+ salts in chemical phosphorus removal (CPR) in activated sludge plants have increased considerably in recent years and their full impacts on downstream processes such as dewaterability and digestibility are not fully understood. In this research, [...] Read more.
The uses of Al3+ and Fe3+ salts in chemical phosphorus removal (CPR) in activated sludge plants have increased considerably in recent years and their full impacts on downstream processes such as dewaterability and digestibility are not fully understood. In this research, the effects of CPR on sludge digestibility and dewaterability were investigated in laboratory-scale experiments using sludge samples from a full-scale wastewater treatment plant. The results of the digestibility tests showed a 21% and 36% reduction in the biogas volume generated during anaerobic digestion of surplus activated sludge at 0.1 g/L doses of Al3+ and Fe3+ salts, respectively. This demonstrates that Al3+ dosing for CPR has less of a reduction effect compared with Fe3+ salts on biogas generation during anaerobic digestion of sludge. The dewaterability tests showed that primary sludge dewaterability was improved by up to 25% by Fe3+ and 16% by Al3+, while that of surplus activated sludge was reduced by 64% and 73%, respectively, at a metal salt dose of 50 mg/L. Consequently, a pre-precipitation process during CPR where phosphorus is removed in the primary tank would, therefore, enhance sludge dewaterability. Full article
(This article belongs to the Special Issue Wastewater Treatment Processes)
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Open AccessArticle
Prediction of N-linked Glycoform Profiles of Monoclonal Antibody with Extracellular Metabolites and Two-Step Intracellular Models
Processes 2019, 7(4), 227; https://doi.org/10.3390/pr7040227
Received: 5 March 2019 / Revised: 11 April 2019 / Accepted: 17 April 2019 / Published: 23 April 2019
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Abstract
Monoclonal antibodies (mAbs) are commonly glycosylated and show varying levels of galactose attachment. A set of experiments in our work showed that the galactosylation level of mAbs was altered by the culture conditions of hybridoma cells. The uridine diphosphate galactose (UDP-Gal) is one [...] Read more.
Monoclonal antibodies (mAbs) are commonly glycosylated and show varying levels of galactose attachment. A set of experiments in our work showed that the galactosylation level of mAbs was altered by the culture conditions of hybridoma cells. The uridine diphosphate galactose (UDP-Gal) is one of the substrates of galactosylation. Based on that, we proposed a two-step model to predict N-linked glycoform profiles by solely using extracellular metabolites from cell culture. At the first step, the flux level of UDP-Gal in each culture was estimated based on a computational flux balance analysis (FBA); its level was found to be linear with the galactosylation degree on mAbs. At the second step, the glycoform profiles especially for G0F (agalactosylated), G1F (monogalactosylated) and G2F (digalactosylated) were predicted by a kinetic model. The model outputs well matched with the experimental data. Our study demonstrated that the integrated mathematical approach combining FBA and kinetic model is a promising strategy to predict glycoform profiles for mAbs during cell culture processes. Full article
(This article belongs to the Special Issue In Silico Metabolic Modeling and Engineering)
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Open AccessArticle
Preparation and Performance of Different Modified Ramie Fabrics Reinforced Anionic Polyamide-6 Composites
Processes 2019, 7(4), 226; https://doi.org/10.3390/pr7040226
Received: 21 February 2019 / Revised: 16 April 2019 / Accepted: 16 April 2019 / Published: 22 April 2019
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Abstract
Anionic polyamide-6 (APA-6) composites are prepared by the VARIM process using different modified ramie fabrics to study the structure and properties of different composites. This study can not only evaluate the optimal modification method for the ramie fabrics, but also further explore the [...] Read more.
Anionic polyamide-6 (APA-6) composites are prepared by the VARIM process using different modified ramie fabrics to study the structure and properties of different composites. This study can not only evaluate the optimal modification method for the ramie fabrics, but also further explore the interface interaction mechanism between ramie fabrics and APA-6. In this article, the ramie fabrics are modified by a pretreatment, coupling agent and alkali modification. Different modification methods have different effects on the structure, surface properties and mechanical properties of ramie fabrics, which will further affect the impregnation process, interfacial and mechanical properties of the composites. Through the performance analysis of different modified ramie fabrics reinforced APA-6 composites, the conversion, crystallinity and molecular weight of these composites are at a high level, which indicate that the polymerization of these composites is well controlled. The coupling agent modified ramie fabrics composites and the pretreated ramie fabrics composites have higher flexural modulus, tensile strength and dynamic mechanical properties. Alkali-modified ramie fabrics composites have slightly lower mechanical properties, which however have the highest interlaminar shear strength and outperformed interface properties of the composites. Full article
(This article belongs to the Special Issue Renewable Polymers: Processing and Chemical Modifications)
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Open AccessFeature PaperReview
Recent Developments in the Photocatalytic Treatment of Cyanide Wastewater: An Approach to Remediation and Recovery of Metals
Processes 2019, 7(4), 225; https://doi.org/10.3390/pr7040225
Received: 6 March 2019 / Revised: 10 April 2019 / Accepted: 15 April 2019 / Published: 20 April 2019
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Abstract
For gold extraction, the most used extraction technique is the Merrill-Crow process, which uses lixiviants as sodium or potassium cyanide for gold leaching at alkaline conditions. The cyanide ion has an affinity not only for gold and silver, but for other metals in [...] Read more.
For gold extraction, the most used extraction technique is the Merrill-Crow process, which uses lixiviants as sodium or potassium cyanide for gold leaching at alkaline conditions. The cyanide ion has an affinity not only for gold and silver, but for other metals in the ores, such as Al, Fe, Cu, Ni, Zn, and other toxic metals like Hg, As, Cr, Co, Pb, Sn, and Mn. After the extraction stage, the resulting wastewater is concentrated at alkaline conditions with concentrations up to 1000 ppm of metals. Photocatalysis is an advanced oxidation process (AOP) able to generate a photoreaction in the solid surface of a semiconductor activated by light. Although it is well known that photocatalytic processes can remove metals in solution, there are no compilations about the researches on photocatalytic removal of metals in wastewater with cyanide. Hence, this review comprises the existing applications of photocatalytic processes to remove metal and in some cases recover cyanide from recalcitrant wastewater from gold extraction. The use of this process, in general, requires the addition of several scavengers in order to force the mechanism to a pathway where the electrons can be transferred to the metal-cyanide matrices, or elsewhere the entire metallic cyanocomplex can be degraded by an oxidative pathway. Full article
(This article belongs to the Special Issue Application of Advanced Oxidation Processes)
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Open AccessFeature PaperArticle
Investigating the Molecular Basis of N-Substituted 1-Hydroxy-4-Sulfamoyl-2-Naphthoate Compounds Binding to Mcl1
Processes 2019, 7(4), 224; https://doi.org/10.3390/pr7040224
Received: 2 April 2019 / Revised: 15 April 2019 / Accepted: 17 April 2019 / Published: 19 April 2019
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Abstract
Myeloid cell leukemia-1 (Mcl1) is an anti–apoptotic protein that has gained considerable attention due to its overexpression activity prevents cell death. Therefore, a potential inhibitor that specifically targets Mcl1 with higher binding affinity is necessary. Recently, a series of N-substituted 1-hydroxy-4-sulfamoyl-2-naphthoate compounds [...] Read more.
Myeloid cell leukemia-1 (Mcl1) is an anti–apoptotic protein that has gained considerable attention due to its overexpression activity prevents cell death. Therefore, a potential inhibitor that specifically targets Mcl1 with higher binding affinity is necessary. Recently, a series of N-substituted 1-hydroxy-4-sulfamoyl-2-naphthoate compounds was reported that targets Mcl1, but its binding mechanism remains unexplored. Here, we attempted to explore the molecular mechanism of binding to Mcl1 using advanced computational approaches: pharmacophore-based 3D-QSAR, docking, and MD simulation. The selected pharmacophore—NNRRR—yielded a statistically significant 3D-QSAR model containing high confidence scores (R2 = 0.9209, Q2 = 0.8459, and RMSE = 0.3473). The contour maps—comprising hydrogen bond donor, hydrophobic, negative ionic and electron withdrawal effects—from our 3D-QSAR model identified the favorable regions crucial for maximum activity. Furthermore, the external validation of the selected model using enrichment and decoys analysis reveals a high predictive power. Also, the screening capacity of the selected model had scores of 0.94, 0.90, and 8.26 from ROC, AUC, and RIE analysis, respectively. The molecular docking of the highly active compound—C40; 4-(N-benzyl-N-(4-(4-chloro-3,5-dimethylphenoxy) phenyl) sulfamoyl)-1-hydroxy-2-naphthoate—predicted the low-energy conformational pose, and the MD simulation revealed crucial details responsible for the molecular mechanism of binding with Mcl1. Full article
(This article belongs to the Special Issue Molecular Dynamics Modeling and Simulation)
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Open AccessArticle
Integer Programming Scheduling Model for Tier-to-Tier Shuttle-Based Storage and Retrieval Systems
Processes 2019, 7(4), 223; https://doi.org/10.3390/pr7040223
Received: 4 March 2019 / Revised: 16 April 2019 / Accepted: 16 April 2019 / Published: 19 April 2019
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Abstract
Shuttle-based storage and retrieval systems (SBS/RSs), a new type of “part-to-picker” system, have attracted public attention because of their flexibility and robustness. The systems consist of two sub-systems—shuttles and lifts—which are responsible for horizontal movements and vertical movements, respectively. SBS/RSs are categorized into [...] Read more.
Shuttle-based storage and retrieval systems (SBS/RSs), a new type of “part-to-picker” system, have attracted public attention because of their flexibility and robustness. The systems consist of two sub-systems—shuttles and lifts—which are responsible for horizontal movements and vertical movements, respectively. SBS/RSs are categorized into tier-to-tier shuttles and tier-captive shuttles. This paper mainly researches SBS/RSs with tier-to-tier shuttles. New challenges have emerged since the commercial simulation-based optimization software has become widely applied for, for instance, task scheduling problems. Specifically, to decrease the idle time of lifts and the waiting time of shuttles, an integer programming scheduling model is proposed to minimize total task time with constraints on orders and devices. The Gurobi linear programming solver was utilized to obtain the optimal order sequence and the shortest operation time. The overall system efficiency was improved using our model. Moreover, the results are significant for reducing capital investment and operating cost. Full article
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Open AccessArticle
Filter Variable Selection Algorithm Using Risk Ratios for Dimensionality Reduction of Healthcare Data for Classification
Processes 2019, 7(4), 222; https://doi.org/10.3390/pr7040222
Received: 20 March 2019 / Revised: 2 April 2019 / Accepted: 15 April 2019 / Published: 18 April 2019
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Abstract
This research developed and tested a filter algorithm that serves to reduce the feature space in healthcare datasets. The algorithm binarizes the dataset, and then separately evaluates the risk ratio of each predictor with the response, and outputs ratios that represent the association [...] Read more.
This research developed and tested a filter algorithm that serves to reduce the feature space in healthcare datasets. The algorithm binarizes the dataset, and then separately evaluates the risk ratio of each predictor with the response, and outputs ratios that represent the association between a predictor and the class attribute. The value of the association translates to the importance rank of the corresponding predictor in determining the outcome. Using Random Forest and Logistic regression classification, the performance of the developed algorithm was compared against the regsubsets and varImp functions, which are unsupervised methods of variable selection. Equally, the proposed algorithm was compared with the supervised Fisher score and Pearson’s correlation feature selection methods. Different datasets were used for the experiment, and, in the majority of the cases, the predictors selected by the new algorithm outperformed those selected by the existing algorithms. The proposed filter algorithm is therefore a reliable alternative for variable ranking in data mining classification tasks with a dichotomous response. Full article
(This article belongs to the Special Issue Big Data in Biology, Life Sciences and Healthcare)
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Open AccessArticle
Convergence of Subtangent-Based Relaxations of Nonlinear Programs
Processes 2019, 7(4), 221; https://doi.org/10.3390/pr7040221
Received: 1 March 2019 / Revised: 5 April 2019 / Accepted: 11 April 2019 / Published: 18 April 2019
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Abstract
Convex relaxations of functions are used to provide bounding information to deterministic global optimization methods for nonconvex systems. To be useful, these relaxations must converge rapidly to the original system as the considered domain shrinks. This article examines the convergence rates of convex [...] Read more.
Convex relaxations of functions are used to provide bounding information to deterministic global optimization methods for nonconvex systems. To be useful, these relaxations must converge rapidly to the original system as the considered domain shrinks. This article examines the convergence rates of convex outer approximations for functions and nonlinear programs (NLPs), constructed using affine subtangents of an existing convex relaxation scheme. It is shown that these outer approximations inherit rapid second-order pointwise convergence from the original scheme under certain assumptions. To support this analysis, the notion of second-order pointwise convergence is extended to constrained optimization problems, and general sufficient conditions for guaranteeing this convergence are developed. The implications are discussed. An implementation of subtangent-based relaxations of NLPs in Julia is discussed and is applied to example problems for illustration. Full article
(This article belongs to the Special Issue Neural Computation and Applications for Sustainable Energy Systems)
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Open AccessFeature PaperArticle
Universal Relationships in Hyperbranched Polymer Architecture for Batch and Continuous Step Growth Polymerization of AB2-Type Monomers
Processes 2019, 7(4), 220; https://doi.org/10.3390/pr7040220
Received: 21 March 2019 / Revised: 13 April 2019 / Accepted: 16 April 2019 / Published: 17 April 2019
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Abstract
Design and control of hyperbranched (HB) polymer architecture by way of reactor operation is key to a successful production of higher-valued HB polymers, and it is essential in order to clarify the fundamental structural characteristics formed in representative types of reactors. In this [...] Read more.
Design and control of hyperbranched (HB) polymer architecture by way of reactor operation is key to a successful production of higher-valued HB polymers, and it is essential in order to clarify the fundamental structural characteristics formed in representative types of reactors. In this article, the irreversible step growth polymerization of AB2 type monomer is investigated by a Monte Carlo simulation method, and the calculation was conducted for a batch and a continuous stirred-tank reactor (CSTR). In a CSTR, a highly branched core region consisting of units with large residence times is formed to give much more compact architecture, compared to batch polymerization. The universal relationships, unchanged by the conversion levels and/or the reactivity ratio, are found for the mean-square radius of gyration Rg2, and the maximum span length LMS. For batch polymerization, the g-ratio of Rg2 of the HB molecule to that for a linear molecule conforms to that for the random branched polymers represented by the Zimm-Stockmayer equation. A single linear equation represents the relationship between Rg2 and LMS, both for batch and CSTR. Appropriate process control in combination with the chemical control of the reactivity of the second B-group promises to produce tailor-made HB polymer architecture. Full article
(This article belongs to the Special Issue Computational Methods for Polymers)
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Open AccessArticle
The Influence of Sorption Pressure on Gas Diffusion in Coal Particles: An Experimental Study
Processes 2019, 7(4), 219; https://doi.org/10.3390/pr7040219
Received: 10 February 2019 / Revised: 3 April 2019 / Accepted: 9 April 2019 / Published: 16 April 2019
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Abstract
Gas pressure changes during the process of coal mine gas drainage and CBM recovery. It is of great importance to understand the influence of sorption pressure on gas diffusion; however, the topic remains controversial in past studies. In this study, four samples with [...] Read more.
Gas pressure changes during the process of coal mine gas drainage and CBM recovery. It is of great importance to understand the influence of sorption pressure on gas diffusion; however, the topic remains controversial in past studies. In this study, four samples with different coal ranks were collected and diffusion experiments were conducted under different pressures through the adsorption and desorption processes. Three widely used models, i.e., the unipore diffusion (UD) model, the bidisperse diffusion (BD) model and the dispersive diffusion (DD) model, were adopted to compare the applicability and to calculate the diffusion coefficients. Results show that for all coal ranks, the BD model and DD model can match the experimental results better than the UD model. Concerning the fast diffusion coefficient Dae of the BD model, three samples display a decreasing trend with increasing gas pressure while the other sample shows a V-type trend. The slow diffusion coefficient Die of BD model increases with gas pressure for all samples, while the ratio β is an intrinsic character of coal and remains constant. For the DD model, the characteristic rate parameter kΦ does not change sharply and the stretching parameter α increases with gas pressure. Both Dae and Die are in proportion to kΦ, which reflect the diffusion rate of gas in the coal. The impacts of pore characteristic on gas diffusion were also analyzed. Although pore size distributions and specific surface areas are different in the four coal samples, correlations are not apparent between pore characteristic and diffusion coefficients. Full article
(This article belongs to the Special Issue Gas Capture Processes)
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Open AccessFeature PaperArticle
Modeling On-Site Combined Heat and Power Systems Coupled to Main Process Operation
Processes 2019, 7(4), 218; https://doi.org/10.3390/pr7040218
Received: 27 February 2019 / Revised: 7 April 2019 / Accepted: 9 April 2019 / Published: 16 April 2019
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Abstract
Many production processes work with on-site Combined Heat and Power (CHP) systems to reduce their operational cost and improve their incomes by selling electricity to the external grid. Optimal management of these plants is key in order to take full advantage of the [...] Read more.
Many production processes work with on-site Combined Heat and Power (CHP) systems to reduce their operational cost and improve their incomes by selling electricity to the external grid. Optimal management of these plants is key in order to take full advantage of the possibilities offered by the different electricity purchase or selling options. Traditionally, this problem is not considered for small cogeneration systems whose electricity generation cannot be decided independently from the main process production rate. In this work, a non-linear gray-box model is proposed in order to deal with this dynamic optimization problem in a simulated sugar factory. The validation shows that with only 52 equations, the whole system behavior is represented correctly and, due to its structure and small size, it can be adapted to any other production process working along a CHP with the same plant configuration. Full article
(This article belongs to the Special Issue Process Modelling and Simulation)
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Open AccessArticle
Exploring Adsorption Process of Lead (II) and Chromium (VI) Ions from Aqueous Solutions on Acid Activated Carbon Prepared from Juniperus procera Leaves
Processes 2019, 7(4), 217; https://doi.org/10.3390/pr7040217
Received: 1 March 2019 / Revised: 9 April 2019 / Accepted: 10 April 2019 / Published: 16 April 2019
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Abstract
The adsorption potential of acid activated carbon prepared from leaves of Juniperus procera to remove Pb(II) and Cr(VI) toxic ions from aqueous solutions was investigated. The effects of solution pH, adsorbent mass, contact time, initial ion concentration and temperature on the biosorption process [...] Read more.
The adsorption potential of acid activated carbon prepared from leaves of Juniperus procera to remove Pb(II) and Cr(VI) toxic ions from aqueous solutions was investigated. The effects of solution pH, adsorbent mass, contact time, initial ion concentration and temperature on the biosorption process were studied, and the optimum conditions were determined. Moreover, Langmuir, Freundlich, Temkin and Dubinin–Radushkevich adsorption isotherm models were applied to analyze adsorption data. Thermodynamic parameters for the adsorption processes were calculated. Adsorption was found to be a spontaneous and endothermic process. In addition, kinetic studies revealed a pseudo-first order kinetics biosorption process. The obtained results suggest that acid activated Juniperus procera leaves powder can be used as a cheap, efficient and environmentally friendly adsorbent material with high removal efficiency up to 98% for Pb(II) and 96% for Cr(VI) at 0.80 and 1.00 g/100 mL, respectively. The duration of the process was 100 min and 120 min for Pb(II) and Cr(VI) ions, respectively. The morphology of the of prepared activated carbon was investigated by scanning electron microscope (SEM). Full article
(This article belongs to the Special Issue Wastewater Treatment Processes)
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Open AccessReview
Alternative Environmentally Friendly Insulating Gases for SF6
Processes 2019, 7(4), 216; https://doi.org/10.3390/pr7040216
Received: 12 March 2019 / Revised: 8 April 2019 / Accepted: 8 April 2019 / Published: 15 April 2019
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Abstract
Sulfur hexafluoride (SF6) shows excellent insulation performance as an insulating gas. It is suitable for various climate conditions due to its low boiling point (−64 °C). Therefore, it has been widely used in power grid equipment. However, its global warming potential [...] Read more.
Sulfur hexafluoride (SF6) shows excellent insulation performance as an insulating gas. It is suitable for various climate conditions due to its low boiling point (−64 °C). Therefore, it has been widely used in power grid equipment. However, its global warming potential (GWP) is 23,500 times higher than that of CO2. Thus, it is imperative to find an environmentally friendly insulating gas with excellent insulation performance, lower GWP, and which is harmless to equipment and workers to replace SF6. In this review, four possible alternatives, including perfluorocarbons, trifluoroiodomethane, perfluorinated ketones, and fluoronitrile are reviewed in terms of basic physicochemical properties, insulation properties, decomposition properties, and compatibility with metals. The influences of trace H2O or O2 on their insulation performances are also discussed. The insulation strengths of these insulating gases were comparable to or higher than that of SF6. The GWPs of these insulating gases were lower than that of SF6. Due to their relatively high boiling point, they should be used as a mixture with buffering gases with low boiling points. Based on these four characteristics, perfluorinated ketones (C5F10O and C6F12O) and fluoronitrile (C4F7N) could partially substitute SF6 in some electrical equipment. Finally, some future needs and perspectives of environmentally friendly insulating gases are addressed for further studies. Full article
(This article belongs to the Special Issue Development of Automated Technologies in Process Chemistry)
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Open AccessArticle
Antifungal and Antibacterial Activities of Musa paradisiaca L. Peel Extract: HPLC Analysis of Phenolic and Flavonoid Contents
Processes 2019, 7(4), 215; https://doi.org/10.3390/pr7040215
Received: 19 March 2019 / Revised: 6 April 2019 / Accepted: 8 April 2019 / Published: 15 April 2019
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Abstract
In the present study, Melia azedarach wood samples that were treated with the methanolic extract of Musa paradisiaca L. peels were evaluated for their antibacterial and antifungal activities against Agrobacterium tumefaciens, Dickeya solani, Erwinia amylovora, Pseudomonas cichorii, Serratia pylmuthica, [...] Read more.
In the present study, Melia azedarach wood samples that were treated with the methanolic extract of Musa paradisiaca L. peels were evaluated for their antibacterial and antifungal activities against Agrobacterium tumefaciens, Dickeya solani, Erwinia amylovora, Pseudomonas cichorii, Serratia pylmuthica, Fusarium culmorum, and Rhizoctonia solani. The strongest antibacterial activity was only found against A. tumefaciens (inhibition zone 90 mm), while the other bacterial strains showed resistance to wood that was treated with the extract. Potential antifungal activity against F. culmorum and R. solani was observed; the mycelial growth inhibition percentages reached 68.88% and 94.07%, respectively, in wood samples that were treated with the 3% methanolic extract of M. paradisiaca peel. HPLC analysis demonstrated the presence of seven phenolic compounds and three flavonoid compounds, as their peaks were matched with the standard compounds in a HPLC analysis. The major constituents of phenolic and flavonoid compounds in mg/100 g dry extract (DE) were ellagic acid (16.19), gallic acid (7.73), rutin (973.08), myricetin (11.52), and naringenin (8.47). The results demonstrated the potential effects of banana peel extract as a natural compound that can protect wood from molds while in use. Full article
(This article belongs to the Special Issue Green Separation and Extraction Processes)
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Open AccessEditorial
Computational Methods Enabling Next-Generation Bioprocesses
Processes 2019, 7(4), 214; https://doi.org/10.3390/pr7040214
Received: 10 April 2019 / Accepted: 10 April 2019 / Published: 12 April 2019
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Abstract
Synthetic biology—the engineering of cells to rewire the biomolecular networks inside them—has witnessed phenomenal progress [...] Full article
(This article belongs to the Special Issue Computational Synthetic Biology)
Open AccessReview
Metabolic Engineering and Fermentation Process Strategies for L-Tryptophan Production by Escherichia coli
Processes 2019, 7(4), 213; https://doi.org/10.3390/pr7040213
Received: 7 March 2019 / Revised: 29 March 2019 / Accepted: 8 April 2019 / Published: 12 April 2019
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Abstract
L-tryptophan is an essential aromatic amino acid that has been widely used in medicine, food, and animal feed. Microbial biosynthesis of L-tryptophan through metabolic engineering approaches represents a sustainable, cost-effective, and environmentally friendly route compared to chemical synthesis. In particular, metabolic pathway engineering [...] Read more.
L-tryptophan is an essential aromatic amino acid that has been widely used in medicine, food, and animal feed. Microbial biosynthesis of L-tryptophan through metabolic engineering approaches represents a sustainable, cost-effective, and environmentally friendly route compared to chemical synthesis. In particular, metabolic pathway engineering allows enhanced product titers by inactivating/blocking the competing pathways, increasing the intracellular level of essential precursors, and overexpressing rate-limiting enzymatic steps. Based on the route of the L-tryptophan biosynthesis pathway, this review presents a systematic and detailed summary of the contemporary metabolic engineering approaches employed for L-tryptophan production. In addition to the engineering of the L-tryptophan biosynthesis pathway, the metabolic engineering modification of carbon source uptake, by-product formation, key regulatory factors, and the polyhydroxybutyrate biosynthesis pathway in L-tryptophan biosynthesis are discussed. Moreover, fermentation bioprocess optimization strategies used for L-tryptophan overproduction are also delineated. Towards the end, the review is wrapped up with the concluding remarks, and future strategies are outlined for the development of a high L-tryptophan production strain. Full article
(This article belongs to the Special Issue Green Sustainable Chemical Processes)
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Open AccessArticle
Modeling of Future Electricity Generation and Emissions Assessment for Pakistan
Processes 2019, 7(4), 212; https://doi.org/10.3390/pr7040212
Received: 31 December 2018 / Revised: 5 April 2019 / Accepted: 8 April 2019 / Published: 12 April 2019
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Abstract
Electricity demand in Pakistan has consistently increased in the past two decades. However, this demand is so far partially met due to insufficient supply, inefficient power plants, high transmission and distribution system losses, lack of effective planning efforts and due coordination. The existing [...] Read more.
Electricity demand in Pakistan has consistently increased in the past two decades. However, this demand is so far partially met due to insufficient supply, inefficient power plants, high transmission and distribution system losses, lack of effective planning efforts and due coordination. The existing electricity generation also largely depends on the imported fossil fuels, which is a huge burden on the national economy alongside causing colossal loss to the environment. It is also evident from existing government plans that electricity generation from low-cost coal fuels in the near future will further increase the emissions. As such, in this study, following the government’s electricity demand forecast, four supply side scenarios for the study period (2013–2035) have been developed using Long-range Energy Alternatives Planning System (LEAP) software tool. These scenarios are Reference scenario (REF) based on the government’s power expansion plans, and three alternative scenarios, which include, More Renewable (MRR), More Hydro (MRH), and More Hydro Nuclear (MRHN). Furthermore, the associated gaseous emissions (CO2, SO2, NOX, CH4, N2O) are projected under each of these scenarios. The results of this study reveal that the alternative scenarios are more environmentally friendly than the REF scenario where penetration of planned coal-based power generation plants would be the major sources of emissions. It is, therefore, recommended that the government, apart from implementing the existing plans, should consider harnessing the renewable energy sources as indispensable energy sources in the future energy mix for electricity generation to reduce the fossil-fuel import bill and to contain the emissions. Full article
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