Records Added in February 2021
Records added in February 2021
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Showing records 55 to 79 of 79. [First] Page: 1 2 3 4 Last
Optimal Non-Convex Combined Heat and Power Economic Dispatch via Improved Artificial Bee Colony Algorithm
Abbas Rabiee, Mohammad Jamadi, Behnam Mohammadi-Ivatloo, Ali Ahmadian
February 22, 2021 (v1)
Keywords: combined heat and power, improved artificial bee colony algorithm, non-convex optimization, valve point effects
It is well accepted that combined heat and power (CHP) generation can increase the efficiency of power and heat generation at the same time. With the increasing penetration of CHPs, determination of economic dispatch of power and heat becomes more complex and challenging. The CHP economic dispatch (CHPED) problem is a challenging optimization problem due to non-linearity and non-convexity in both objective function and constraints. Hence, in this paper a novel meta-heuristic algorithm, namely improved artificial bee colony (IABC) algorithm is proposed to solve the CHPED problem. The valve-point effects, power losses as well as the feasible operation region of CHP units are taken into account in the proposed CHPED problem model and the optimal dispatch of power/heat outputs of CHP units is determined via the proposed IABC algorithm. The proposed algorithm is applied on three test systems, in which two of them are large-scale CHPED benchmarks. The obtained results and comprehensive compa... [more]
Modeling of Spiral Wound Membranes for Gas Separations—Part II: Data Reconciliation for Online Monitoring
Diego Queiroz Faria de Menezes, Marília Caroline Cavalcante de Sá, Tahyná Barbalho Fontoura, Thiago Koichi Anzai, Fabio Cesar Diehl, Pedro Henrique Thompson, Jose Carlos Pinto
February 22, 2021 (v1)
Keywords: data reconciliation, membrane, monitoring, online, real-time
The present work presents a methodology based on data reconciliation to monitor membrane separation processes reliably, online and in real time for the first time. The proposed methodology was implemented in accordance with the following steps: data acquisition; data pre-treatment; data characterization; data reconciliation; gross error detection; and critical evaluation of measured data with a soft sensor. The acquisition of data constituted the slowest stage of the monitoring process, as expected in real-time applications. The pre-treatment stage was fundamental to assure the robustness of the code and the initial characterization of collected data was carried out offline. The characterization of the data showed that steady-state modeling of the process would be appropriate, also allowing the implementation of faster numerical procedures for the data reconciliation step. The data reconciliation step performed well, quickly and consistently. Thus, data reconciliation allowed the estim... [more]
Pharmacological Properties and Chemical Profiles of Passiflora foetida L. Extracts: Novel Insights for Pharmaceuticals and Nutraceuticals
Annalisa Chiavaroli, Simonetta Cristina Di Simone, Kouadio Ibrahime Sinan, Maria Chiara Ciferri, Giancarlo Angeles Flores, Gokhan Zengin, Ouattara Katinan Etienne, Gunes Ak, Mohamad Fawzi Mahomoodally, Sharmeen Jugreet, Zoltán Cziáky, József Jekő, Lucia Recinella, Luigi Brunetti, Sheila Leone, Paola Angelini, Roberto Venanzoni, Luigi Menghini, Claudio Ferrante, Giustino Orlando
February 22, 2021 (v1)
Subject: Biosystems
Keywords: anti-oxidant/anti-inflammatory effects, bioinformatics/network pharmacology, chemical profile, neuroprotection, Passiflora foetida, skin protection
In the present study, Passiflora foetida extracts characterized by different polarities were studied for their phytochemical profile, enzyme inhibitory, and antioxidant potentials. In silico, in vitro and ex vivo studies were also carried out on methanol and water extracts for predicting pharmacokinetics and pharmacodynamics. In this regard, neuronal HypoE22 cells, isolated mouse skin tissues, and pathogen dermatophytes strains were exposed to extracts. Emphasis was given to the preventing effects induced by the extracts on hydrogen peroxide-induced alterations of prostaglandin E2 (PGE2), l-dopa, and serotonin. Chemical analysis revealed the presence of similar compounds in infusion and methanolic extracts. The ex vivo studies also showed protective skin properties by P. foetida water and methanol extracts, as evidenced by the decrease of hydrogen peroxide-induced PGE2 level. Additionally, the blunting effects on hydrogen peroxide-induced l-dopa levels are consistent with the anti-tyro... [more]
The Role of Technological Innovation in a Dynamic Model of the Environmental Supply Chain Curve: Evidence from a Panel of 102 Countries
Muhammad Khalid Anser, Muhammad Azhar Khan, Usama Awan, Rubeena Batool, Khalid Zaman, Muhammad Imran, Sasmoko, Yasinta Indrianti, Aqeel Khan, Zainudin Abu Bakar
February 22, 2021 (v1)
Subject: Energy Policy
Keywords: carbon damages, differenced panel GMM, economic growth, green supply chain management, logistics performance indices, technological factors
Advancing smart production systems for green production remains a crucial priority for manufacturers, while the vision to achieve green supply chain management process (GSCMP) remains obstructed due to using less fuel-efficient technologies. This study suggested an intelligent logistics design that infused technological indicators with logistics performance indices (LPIs) to minimize carbon damages in a panel of 102 countries. The study used patent applications and trademark applications to analyze the technological progress, whereas LPIs—i.e., LPI-1 for assessing quality and competence services, and LPI-2 for trade and transport infrastructure—are used to determine supply chain management process across countries. The results show that carbon damages follow a U-shaped structure with technology-induced LPIs (TI-LPIs) and GDP per capita. The country’s GDP per capita and TI-LPIs decrease carbon damages up to US$15,000,000, while the moderation of patents application (and trademark applic... [more]
Effects in Band Gap for Photocatalysis in TiO2 Support by Adding Gold and Ruthenium
Omar Ricardo Fonseca-Cervantes, Alejandro Pérez-Larios, Víctor Hugo Romero Arellano, Belkis Sulbaran-Rangel, Carlos Alberto Guzmán González
February 22, 2021 (v1)
Keywords: oxidized and reduced oxidation states, photocatalysis, sol–gel method, supported on TiO2
One of the key features of a nano catalyst for photocatalysis is the band gap, because, through its analysis, the potential of the catalyst can be determined. In this investigation, the impact on the band gap of different catalysts made by the sol−gel method, compared with TiO2 P25 Sigma-Aldrich, showing the effect of using gold or ruthenium as a metal supported on TiO2, with two different dosage percentages of 1 and 3 percent, was analysed. Additionally, two oxidation states of the catalyst, the reduced form and the oxidized form of the metal, were used to see the effect on the band gap. The experiments show that the gold addition has a higher beneficial effect on the band gap for the UV region (ultra violet region), and the ruthenium addition has a higher beneficial effect for the UV/visible region. The preferred oxidation state for the band gap was the oxidized state. The characterisation of the catalyst provided an insight into the relation between the band gap and the catalyst its... [more]
Investigation of Itaconic Acid Separation by Operating a Commercialized Electrodialysis Unit with Bipolar Membranes
Tamás Rózsenberszki, Péter Komáromy, Enikő Kőrösi, Péter Bakonyi, Nándor Nemestóthy, Katalin Bélafi-Bakó
February 22, 2021 (v1)
Keywords: bipolar membrane, by-product, electrodialysis, integrated system, itaconic acid
Nowadays, the merging of membrane and fermentation technologies is receiving significant attention such as in the case of itaconic acid (IA) production, which is considered as a value-added chemical. Its biotechnological production is already industrially established; however, the improvements of its fermentative and recovery steps remain topics of significant interest due to sustainable development trends. With an adequate downstream process, the total price of IA production can be reduced. For the task of IA recovery, a contemporary electro-membrane separation processes, electrodialysis with bipolar membranes (EDBM), was proposed and employed in this work. In the experiments, the laboratory-scale, commercialized EDBM unit (P EDR-Z/4x) was operated to separate IA from various model solutions compromised of IA (5−33 g/L), glucose (varied in 15−33 g/L as a residual substrate during IA fermentation) and malic acid (varied in 0−1 g/L as a realistic by-product of IA fermentation) under dif... [more]
Study of H2S Removal Capability from Simulated Biogas by Using Waste-Derived Adsorbent Materials
Hua Lun Zhu, Davide Papurello, Marta Gandiglio, Andrea Lanzini, Isil Akpinar, Paul R. Shearing, George Manos, Dan J.L. Brett, Ye Shui Zhang
February 3, 2021 (v1)
Keywords: activated carbon, Adsorption, biochar, Catalysis, circular economy, H2S, waste
Three waste-derived adsorbent materials (wood-derived biochar, sludge-derived activated carbon and activated ash) were pre-activated at the laboratory scale to apply them for the removal of H2S from a biogas stream. The H2S removal capabilities of each material were measured by a mass spectrometer, to detect the H2S concentration after the adsorption in an ambient environment. The activated ash adsorbent has the highest removal capacity at 3.22 mgH2S g−1, while wood-derived biochar has slightly lower H2S removal capability (2.2 mgH2S g−1). The physicochemical properties of pristine and spent materials were characterized by the thermogravimetric analyzer, elemental analysis, X-ray fluorescence spectroscopy and N2 adsorption and desorption. Wood-derived biochar is a highly porous material that adsorbs H2S by physical adsorption of the mesoporous structure. Activated ash is a non-porous material which adsorbs H2S by the reaction between the alkaline compositions and H2S. This study shows... [more]
Screening and Application of Chitin Synthase Inhibitors
Xiaozai Shi, Shuo Qiu, Yingling Bao, Hanchi Chen, Yuele Lu, Xiaolong Chen
February 3, 2021 (v1)
Subject: Biosystems
Keywords: biological activity research, chitin synthase, inhibitors, maleimides
Chitin is an important part of the fungal cell wall, but is not found in plants and mammals, so chitin synthase (CHS) can be a green fungicide target. In this paper, 35 maleimide compounds were designed and synthesized as CHS inhibitors. All the screened compounds showed different degrees of CHS inhibitory activity and antifungal activity in vitro. In particular, the half−inhibitory concentration (IC50) value of compound 20 on CHS was 0.12 mM, and the inhibitory effect was better than that of the control polyoxin B (IC50 = 0.19 mM). At the same time, this compound also showed good antifungal activity and has further development value.
Subcritical Water Extraction of Epigallocatechin Gallate from Camellia sinensis and Optimization Study Using Response Surface Methodology
Nguyen Tuan Hiep, Hoang Thanh Duong, Dang Tuan Anh, Nguyen Hoai Nguyen, Do Quang Thai, Do Thi Thuy Linh, Vu Thi Huong Anh, Nguyen Minh Khoi
February 3, 2021 (v1)
Keywords: Camellia sinensis, Modelling, response surface methodology, subcritical water extraction
Background: Camellia sinensis is a plant whose leaves and buds are used to produce tea. With many medicinal activities already found, green tea has been consumed widely in the world. Methods: The subcritical water extraction (SWE) of epigallocatechin gallate (EGCG) from green tea leaves and the effect of the different extraction conditions are investigated by response surface methodology (RSM). Furthermore, the model of the extraction processes is reviewed for application at the industrial scale. Results: Based on the RSM data, the maximum yield of extraction is determined via optimizing different parameters of the extraction processes. Optimal conditions are as follows: extraction time of 6 min, extraction temperature at 120 °C, and a sample/solvent ratio of 1:40 g/mL. Under such conditions, the best yield of EGCG is 4.665%. Moreover, the model of the extraction processes, which can be utilized for industry scale purpose, indicates a good correlation with the experimental data. Conclu... [more]
Numerical Simulations of Molten Breakup Behaviors of a de Laval-Type Nozzle, and the Effects of Atomization Parameters on Particle Size Distribution
Lianghui Xu, Xianglin Zhou, Jinghao Li, Yunfei Hu, Hang Qi, Wei Wen, Kaiping Du, Yao Ma, Yueguang Yu
February 3, 2021 (v1)
Keywords: breakup, de Laval-type nozzle, discrete particle model, gas atomization, particle size distribution
In this work, an atomizer with a de Laval-type nozzle is designed and studied by commercial computational fluid dynamics (CFD) software, and the secondary breakup process during atomization is simulated by two-way coupling and the discrete particle model (DPM) using the Euler-Lagrange method. The simulation result demonstrates that the gas flow patterns greatly change with the introduction of liquid droplets, which clearly indicates that the mass loading effect is quite significant as a result of the gas-droplet interactions. An hourglass shape of the cloud of disintegrating molten metal particles is observed by using a stochastic tracking model. Finally, this simulation approach is used for the quantitative evaluation of the effects of altering the atomizing process conditions (gas-to-melt ratio, operating pressure P, and operating gas temperature T) and nozzle geometry (protrusion length h, half-taper angle α, and gas slit nozzle diameter D) on the particle size distribution of the p... [more]
Analysis of Influence of Floating-Deck Height on Oil-Vapor Migration and Emission of Internal Floating-Roof Tank Based on Numerical Simulation and Wind-Tunnel Experiment
Gao Zhang, Fengyu Huang, Weiqiu Huang, Zhongquan Zhu, Jie Fang, Hong Ji, Lipei Fu, Xianhang Sun
February 3, 2021 (v1)
Keywords: diffusion, evaporation loss, internal floating-roof tank, numerical simulation, wind tunnel experiment
Internal floating-roof tanks (IFRTs) are widely used to store light oil and chemical products. However, if the annular-rim gap around the floating deck becomes wider due to abrasion and aging of the sealing arrangement, the static breathing loss from the rim gap will be correspondingly aggravated. To investigate the oil-vapor migration and emissions from an IFRT, the effects of varying both the floating-deck height and wind speed on the oil-vapor diffusion were analyzed by performing numerical simulations and wind-tunnel experiments. The results demonstrate that the gas space volume and the wind speed of an IFRT greatly influence the vapor-loss rate of the IFRT. The larger the gas space volume, the weaker the airflow exchange between the inside and outside of the tank, thereby facilitating oil-vapor accumulation in the gas space of the tank. Furthermore, the loss rate of the IFRT is positively correlated with wind speed. Meanwhile, negative pressures and the vortexes formed on the leew... [more]
Comparison of Dimethylformamide with Dimethylsulfoxide for Quality Improvement of Distillate Recovered from Waste Plastic Pyrolysis Oil
Su Jin Kim
February 3, 2021 (v1)
Keywords: DMF equilibrium extraction, DMSO equilibrium extraction, paraffin enrichment, waste plastic pyrolysis oil
As a part of improving the quality of the distillate (distilling temperature 120−350 °C) recovered from waste plastic pyrolysis oil (WPPO) by simple distillation, the enrichment of paraffin components present in the distillate was compared by the equilibrium extraction of dimethylformamide (DMF) and dimethylsulfoxide (DMSO). Regardless of the solvent used, the concentration increase rate of the paraffin component in the raffinate relative to the raw material was reduced by increasing the mass fraction of water in the solvent in an initial state. On the other hand, it increased by increasing the mass ratio of the solvent to the raw material in an initial state. The enrichment performance of paraffin component in raffinate recovered by DMF was higher than that by DMSO under the same experimental conditions. Furthermore, the two solvents were compared by adding color and the waxing phenomena of recovered raffinate to assess the enrichment performance of paraffin components.
Scheduling Two Identical Parallel Machines Subjected to Release Times, Delivery Times and Unavailability Constraints
Adel M. Al-Shayea, Mustafa Saleh, Moath Alatefi, Mageed Ghaleb
February 3, 2021 (v1)
Keywords: Cmax, delivery times, genetic algorithm (GA), Optimization, parallel machine scheduling, preventive maintenance, release times
This paper proposes a genetic algorithm (GA) for scheduling two identical parallel machines subjected to release times and delivery times, where the machines are periodically unavailable. To make the problem more practical, we assumed that the machines are undergoing periodic maintenance rather than making them always available. The objective is to minimize the makespan (Cmax). A lower bound (LB) of the makespan for the considered problem was proposed. The GA performance was evaluated in terms of the relative percentage deviation (RPD) (the relative distance to the LB) and central processing unit (CPU) time. Response surface methodology (RSM) was used to optimize the GA parameters, namely, population size, crossover probability, mutation probability, mutation ratio, and pressure selection, which simultaneously minimize the RPD and CPU time. The optimized settings of the GA parameters were used to further analyze the scheduling problem. Factorial design of the scheduling problem input v... [more]
Supercritical Fluid Extraction of Compounds of Pharmaceutical Interest from Wendita calysina (Burrito)
Lucia Baldino, Ernesto Reverchon
February 3, 2021 (v1)
Subject: Biosystems
Keywords: anticancer, antimicrobial, burrito, D-carvone, fractional separation, supercritical fluid extraction, Wendita calysina
Wendita calysina (commonly known as burrito) is an indigenous Paraguayan medical plat, whose essential oil (EO) is characterized by some pharmaceutical properties. In particular, the main component is D-carvone, with anticancer action and antimicrobial properties against various microorganisms. In this work, supercritical CO2 (SC-CO2) was used for the extraction of volatile compounds from this plant, selecting different operative conditions to optimize the extract yield and purity. Pressure was varied from 80 to 250 bar, and two CO2 flow rates (0.8 kg/h and 1.2 kg/h) were tested. The highest EO percentage in the extract was obtained operating at 100 bar and 40 °C, using ground Wendita calysina leaves of 250 µm. CO2 flow rate did not influence the extraction yield, indicating that an internal mass transfer resistance governs this process. The largely prevailing compound identified in the extract was D-carvone, with a mean percentage up to 90% w/w.
Liposomes: From Bangham to Supercritical Fluids
Paolo Trucillo, Roberta Campardelli, Ernesto Reverchon
February 3, 2021 (v1)
Subject: Biosystems
Keywords: drug delivery systems, liposome characterization, liposome production, supercritical fluids, vesicles
Liposomes are spherical vesicles made up of an aqueous core surrounded by phospholipids. These delivery systems (DS) are largely employed as drug carriers in several industrial fields, such as pharmaceutical and nutraceutical fields. The aim of this short review is to provide a fast overview on the main fundamentals of liposomes, thought as a compact guide for researchers and students that want to approach this topic for the first time. The mini-review will focus on the definitions, production methods and characterization protocols of the liposomes produced, making a critical comparison of the main conventional and supercritical based manufacturing methods available. The literature was analyzed deeply from the first works by Dr. Bangham in 1965 to the most recent supercritical fluid applications. The advantages and disadvantages of conventional and high-pressure processes will be described in terms of solvent elimination, production at the nanometric (50−300 nm) and micrometric level (... [more]
Experimental Research on the Optimization and Evaluation of the Polymer/Chromium-Ion Deep Profile Control System for the Fractured Low-Permeability Reservoirs
Daiyin Yin, Shuang Song, Qi Xu, Kai Liu
February 3, 2021 (v1)
Keywords: deep profile control system, fractured low-permeability reservoirs, polymer/chromium-ion
The matrix/fracture conductivity of a fractured low-permeability reservoir is variable, and its heterogeneity is serious. When carrying out deep profile control measures, it is difficult to inject under the premise of ensuring the plugging effect. According to the characteristics of the fractured low-permeability reservoir in Chaoyanggou Oilfield, the polymer/chromium ion deep profile control system was optimized via a viscosity evaluation experiment, liquidity experiment and oil displacement experiment. The experimental results show that the high molecular weight main agent/low concentration system and low molecular weight main agent/high concentration system can meet the gel strength requirement. The evaluation results of the injection ability and plugging performance of the fractured low-permeability core show that a high molecular weight profile control system is difficult to inject, while a low molecular weight profile control system has a poor plugging performance and high cost a... [more]
Numerical Study of the Filling Process of a Liquid Hydrogen Storage Tank under Different Sloshing Conditions
Guomeng Wei, Jianfei Zhang
February 3, 2021 (v1)
Keywords: gas-liquid phase change, liquid hydrogen storage tank, microgravity, no-vent fill, sloshing, three-dimensional numerical model
Cryogenic vessels are widely used in many areas, such as liquefied natural gas (LNG), aerospace, and medical fields. A suitable filling method is one of the prerequisites for the effective use of cryogenic containers. In this study, the filling process for the sloshing condition of a liquid hydrogen storage tank is numerically simulated and analyzed by coupling the sloshing model and the phase-change model. The effects of different sloshing conditions during the filling process are investigated by changing the amplitude and frequency of the sloshing. Within the scope of this study, there is a critical value for the effect of sloshing conditions on the pressure curve during the filling process. The critical value corresponds to a frequency f equal to 3 Hz and an amplitude A equal to 0.03 m. According to the simulation results, when the sloshing exceeds the critical value, the internal pressure curve of the storage tank increases significantly. Under microgravity conditions, within the s... [more]
Process of Creating an Integrated Design and Manufacturing Environment as Part of the Structure of Industry 4.0
Andrzej Paszkiewicz, Marek Bolanowski, Grzegorz Budzik, Łukasz Przeszłowski, Mariusz Oleksy
February 3, 2021 (v1)
Keywords: 3D printing, additive manufacturing, computer systems and networks, IoT, manufacturing process
This paper presents the process for creating an integrated design and manufacturing environment supporting 3D printing as part of the structure of Industry 4.0. This process is based on a developed framework for the design of modern automated and computerized infrastructure. The task of the described system is to combine all the steps included in the operating range of incremental systems based on an IT platform by integrating data from individual areas, such as IT systems supporting remote 3D printing. The proposed framework for incremental processes is a universal solution that can be defined in detail by a single organizational unit running 3D printing, as well as by a cluster of entities related to 3D printing. In the initial phase, the framework design includes a set of guidelines for IT (Information Technology) systems that facilitate the construction of individual elements and the creation of communication interfaces. In subsequent stages, the framework may already implement ele... [more]
Significance of Pretreatment in Enhancing the Performance of Dry Anaerobic Digestion of Food Waste: An Insight on Full Scale Implementation Strategy with Theoretical Analogy
Vijayalakshmi Arelli, Sudharshan Juntupally, Sameena Begum, Gangagni Rao Anupoju
February 3, 2021 (v1)
Keywords: dry anaerobic digestion, food waste, methane yield, pretreatment
The aim of this study was to treat food waste containing 25% total solids (TS) through dry anaerobic digestion (dry AD) process at various pressures (0.5 to 2.5 kg/cm2) and different time duration (20 to 100 min) to understand the impact of pretreatment in enhancing the methane generation potential along with insights on scale up. The findings revealed that vs. reduction and methane yield of 60% and 0.25 L CH4/(g VSadded) can be achieved with pretreated food waste at two kilograms per square centimeter, while pretreatment of food waste at 2 kg/cm2 for 100 min enhanced the vs. reduction from 60% to 85% and methane yield from 0.25 to 0.368 L CH4/(g VSadded). However, the net energy indicated that 40 min of pre -treatment at two kilograms per square centimeter can be a suitable option as methane yield and vs. reduction of 0.272 L CH4/(g VSadded) and 70%, respectively was achieved. The vs. reduction and the methane yield of 45% and 0.14 L CH4/(g VSadded), respectively was obtained from unt... [more]
Performance Analysis and Working Fluid Selection for Single and Two Stages Vapor Compression Refrigeration Cycles
Bahaa Saleh, Ayman A. Aly, Mishal Alsehli, Ashraf Elfasakhany, Mohamed M. Bassuoni
February 3, 2021 (v1)
Keywords: azeotropic mixtures, cycle performance, flash intercooler, pure refrigerants, refrigeration cycle
Screening for alternative refrigerants with high energy efficiency and low environmental impacts is one of the highest challenges of the refrigeration sector. This paper investigates the performance and refrigerant screening for single and two stages vapor compression refrigeration cycles. Several pure hydrocarbons, hydrofluorocarbons, hydrofluoroolefins, fluorinated ethers, and binary azeotropic mixtures are proposed as alternative refrigerants to substitute R22 and R134a due to their environmental impacts. The BACKONE equation of state is used to compute the thermodynamic properties of the candidates. The results show that the maximum coefficients of performance (COP) for single and two stage cycles using pure substances are achieved using cyclopentane with values of 4.14 and 4.35, respectively. On the other side, the maximum COP for the two cycles using azeotropic mixtures is accomplished using R134a + RE170 with values of 3.96 and 4.27, respectively. The two-stage cycle presents ga... [more]
Glycerol Oxidation over Supported Gold Catalysts: The Combined Effect of Au Particle Size and Basicity of Support
Ekaterina Pakrieva, Ekaterina Kolobova, Dmitrii German, Marta Stucchi, Alberto Villa, Laura Prati, Sónia. A.C. Carabineiro, Nina Bogdanchikova, Vicente Cortés Corberán, Alexey Pestryakov
February 3, 2021 (v1)
Keywords: base additives, catalyst selectivity, glyceric acid, glycerol oxidation, glycolic acid, gold catalysts, tartronic acid
Gold nanoparticles supported on various oxides (CeO2, CeO2/TiO2, MgO, MgO/TiO2, La2O3, La2O3/TiO2) (with 4 wt.% Au loading) were investigated in the liquid (aqueous) phase oxidation of glycerol by molecular oxygen under mild conditions, in the presence of alkaline earth (CaO, SrO and MgO) or alkaline (NaOH) bases. Full conversion and selectivity between 38 and 68% to sodium glycerate were observed on different Au supported catalysts (Au/MgO/TiO2, Au/La2O3/TiO2, Au/CeO2 and Au/CeO2/TiO2). The combined effect of Au particle size and basicity of the support was suggested as the determining factor of the activity. Agglomeration of gold nanoparticles, found after the reaction, led to the deactivation of the catalysts, which prevents the further oxidation of sodium glycerate into sodium tartronate. Promising results were obtained with the use of alkaline earth bases (CaO, SrO, MgO), leading to the formation of free carboxylic acids instead of salts, which are formed in the presence of the mo... [more]
Efficacy of Ultrasonic-Assisted Curing Is Dependent on Muscle Size and Ultrasonication System
Bianka Y. Cruz-Garibaldi, Alma D. Alarcon-Rojo, Mariana Huerta-Jimenez, Ivan A. Garcia-Galicia, Luis M. Carrillo-Lopez
February 3, 2021 (v1)
Keywords: cured meat, high-intensity ultrasound, microbiota, relative fresh weight
Ultrasound-assisted marinade is a promising technology for reducing the time of traditional immersion marination. This study evaluated the effect of the ultrasonic system (bath or probe, amplitude 50 or 100%) and muscle sample size (3 or 5 cm3) on physicochemical quality, yield (salt content, fresh weight, and relative fresh weight), and bacteria counts associated with pork. The results showed a significantly high salt (p < 0.0001) content in 3 cm3 (11.54%) and 5 cm3 (8.88%) samples after 24 h marination by immersion. The 3 cm3 cubes marinated in a 100% probe system for 20 min presented an amount of salt (9.55%) that was quite close to the controls. The 3 cm3 samples treated by immersion and in a 50% probe system gained more relative weight (in relation to the initial weight, 7.45 and 6.64%, respectively) after 7 d at 4 °C. Meanwhile the 5 cm3 cubes marinated by immersion gained 8.1%. The other treatments showed a weight loss after treatment. Although significant differences were fo... [more]
The Liquid−Liquid Dispersion Homogeneity in a Vessel Agitated by a High-Shear Sawtooth Impeller
Roman Formánek, Radek Šulc
February 3, 2021 (v1)
Subject: Other
Keywords: dispersion, drop size distribution, homogeneity, immiscible liquids, kinetics, Sauter mean diameter, vessel
The agitation of immiscible liquids or solid suspensions is a frequent operation in chemical and metallurgical industries. The product quality yield and economy of the processes are significantly affected by mixing conditions. Prediction of mean drop size distribution (DSD) during agitation is fundamental for processes in many branches of industry where the mass transfer is crucial. This contribution aims to analyze the homogeneity of a dispersed system in a vessel agitated by a high-shear sawtooth impeller. The homogeneity of liquid−liquid dispersion is determined by comparison of Sauter mean diameters and drop size distribution (DSD) from different measured regions and for various dispersion times. The experiments were carried out in a baffled vessel for various impeller speeds. The sizes of droplets were obtained by the in-situ measurement technique and by the image analysis (IA) method.
Simulation-Based Optimization of a Two-Echelon Continuous Review Inventory Model with Lot Size-Dependent Lead Time
Ibrahim Alharkan, Mustafa Saleh, Mageed Ghaleb, Abdulsalam Farhan, Ahmed Badwelan
February 3, 2021 (v1)
Keywords: Arena, dependent lead time, simulation-based optimization, stochastic inventory problem
This study analyzes a stochastic continuous review inventory system (Q,r) using a simulation-based optimization model. The lead time depends on lot size, unit production time, setup time, and a shop floor factor that represents moving, waiting, and lot size inspection times. A simulation-based model is proposed for optimizing order quantity (Q) and reorder point (r) that minimize the total inventory costs (holding, backlogging, and ordering costs) in a two-echelon supply chain, which consists of two identical retailers, a distributor, and a supplier. The simulation model is created with Arena software and validated using an analytical model. The model is interfaced with the OptQuest optimization tool, which is embedded in the Arena software, to search for the least cost lot sizes and reorder points. The proposed model is designed for general demand distributions that are too complex to be solved analytically. Hence, for the first time, the present study considers the stochastic invento... [more]
Accumulation of Airborne Toxic Elements and Photosynthetic Performance of Lolium multiflorum L. Leaves
Klaudia Borowiak, Anna Budka, Marta Lisiak-Zielińska, Anetta Hanć, Janina Zbierska, Danuta Barałkiewicz, Dariusz Kayzer, Renata Gaj, Anna Szymczak-Graczyk, Jolanta Kanclerz
February 3, 2021 (v1)
Keywords: air pollution, intercellular CO2, net photosynthesis rate, stomatal conductance, trace elements, transpiration rate
In this study, we aimed to investigate the accumulation of airborne trace elements in Lolium multiflorum leaves concerning photosynthetic activity parameters. Five sites for four 28-day series of plant exposition were selected. The concentration of trace elements in leaves was measured after each series, while photosynthetic activity parameters were measured three times during each series. Net photosynthesis rate (PN) and stomatal conductance (gs) were mostly negatively associated with all analyzed trace elements, unlike to CO2 concentrations (Ci). Arsenic was found with opposite trend in two exposure series. The high accumulation of Cd and Pb in plants recorded at two sites was mostly related to lowest PN and gs. Similar tendency for PN was found at sites and series with the highest Cr and Ni content in plants. L. multiflorum revealed a medium-level accumulation of trace elements and a low tolerance of the photosynthetic process to the presence of trace elements in ambient air.
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