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Showing records 101 to 125 of 203. [First] Page: 1 2 3 4 5 6 7 8 9 Last
Characterization, Expression Profiling, and Functional Analyses of a 4CL-Like Gene of Populus trichocarpa
Hui Wei, Chen Xu, Ali Movahedi, Weibo Sun, Qiang Zhuge
April 15, 2019 (v1)
Subject: Biosystems
Keywords: 4CL-like, ACS, box I domain, box II domain, CL, Populus trichocarpa, PTS
Adenosine 5′-monophosphate (AMP) (adenylate)-forming acetyl-CoA synthetase (ACS) catalyzes the formation of acetyl-coenzyme A (CoA), and the ACS family is closely related to the 4-coumarate CoA ligase (4CL) family. In this study, a 4CL-like gene was cloned from Populus trichocarpa and named Pt4CL-like. Characterization of Pt4CL-like, using bioinformatics, showed that it contained box I and box II domains at the end of the C-terminal sequence, and there is a characteristic sequence of ACS, namely, peroxisome-targeting sequence (PTS). Real-time PCR results showed that the 4CL-like gene was expressed in all tissues tested, and was highly expressed in the stems. A denaturation and renaturation process was conducted, and the recombinant Pt4CL-like protein was purified through HisTrapTM high performance affinity chromatography. It showed Pt4CL-like protein did not catalyze substrates of 4CL, but could significantly catalyzed sodium acetate. These results indicate that Pt4CL-like protein belo... [more]
Adsorption of Organic Constituents from Reverse Osmosis Concentrate in Coal Chemical Industry by Coking Coal
Hongxiang Xu, Qizheng Qin, Changfeng Zhang, Kejia Ning, Rong Zhao, Penghui Wang, Jiushuai Deng, Gen Huang
April 15, 2019 (v1)
Keywords: Adsorption, adsorption mechanism, aromatic structure, kinetics
To solve the unwieldy problem of coal chemical wastewater reverse osmosis concentrate (ROC), a novel treatment method in which coking coal was used to adsorb the organic from ROC and the adsorption mechanism involved was investigated. The results showed that the organic components in the ROC of coal chemical industry can be effectively absorbed by the coking coal and the total organic carbon, UV254 and chromaticity of treated ROC reduced by 70.18%, 70.15% and 59.55%, respectively, at the coking coal dosage of 80 g/L. The isothermal adsorption data were fitted to the Langmuir model well. The kinetics were expressed well by the quasi-second-order kinetic model. The intragranular diffusion model and the BET (Acronym for three scientists: Brunauer⁻Emmett⁻Teller) test showed that the adsorption occurred mainly on the surface of the coking coal and its macropores and mesopores. When the pollutants further diffused to the mesopores and micropores, the adsorption rate decreased. The result of... [more]
Application of Supergravity Technology in a TEG Dehydration Process for Offshore Platforms
Hongfang Lu, Guoguang Ma, Mohammadamin Azimi, Lingdi Fu
April 15, 2019 (v1)
Keywords: Higee, natural gas dehydration, supergravity technology, TEG
In the dehydration process of offshore natural gas production, due to the site limitation of the platform, if the conventional triethylene glycol (TEG) dehydration process is employed, the size of the absorption tower is usually small. However, in the case of fluctuations in raw material gas and large gas production, it is easy to cause a large loss of TEG and a flooding event, resulting in the water dew point of natural gas not meeting the requirements. Therefore, combined with the dehydration process of TEG and supergravity technology, a new dehydration process of natural gas suitable for offshore platforms is proposed in this paper. The principle and process of the TEG dehydration process based on supergravity technology are discussed by establishing a mass transfer model. The laboratory experiment of the new process is carried out, and the effects of TEG flow rate, super-gravity packed bed rotation speed, and gas flow rate on the air dew point are obtained. By studying the dewateri... [more]
Optimization of the Melting Performance of a Thermal Energy Storage Unit with Fractal Net Fins
Jiayi Zheng, Cheng Yu, Taotao Chen, Yanshun Yu, Fang Wang
April 15, 2019 (v1)
Keywords: fin, fractal, melting, net, phase change
In this study, fractal net fins were introduced to improve the melting performance of a thermal energy storage unit. A transient model for melting heat transfer for phase change material (PCM) was presented and numerically analyzed, to study the melting performance in a thermal energy storage unit using fractal net fins. The melting phase change process was modelled using the apparent heat capacity method. The evolutions of temperature and the liquid fraction in the thermal energy storage unit were investigated and discussed. The effects of the length and width ratios of the fractal net on melting performance were analyzed to obtain the optimal fin configuration. The results indicated that the fractal net fins significantly enhanced the melting heat transfer performance of the PCM in a thermal energy storage unit. The fractal net fins configuration was optimal when the length and width ratios of the fractal net were 0.5. The temperature response at the corner points of the fractal net... [more]
Efficient Removal of Hexavalent Chromium from Wastewater with Electro-Reduction
Hao Peng, Yumeng Leng, Qinzhe Cheng, Qian Shang, Jiancheng Shu, Jing Guo
April 15, 2019 (v1)
Keywords: acidic medium, chromium, electro-reduction
Removal of hexavalent chromium had attracted much attention as it is a hazardous contaminant. An electrocoagulation-like technology electro-reduction was applied. The chromium (VI) in the wastewater was reduced to chromium (III) by the electron supplied by electricity power and Fe2+, formed from corrosion of steel electrodes in acidic conditions. The mechanism and parameters affecting the reaction were investigated. The results optimized by response surface methodology indicated that the influence of single factor on the reduction efficiency followed the order: A: dosage of H₂SO₄ > C: reaction time > D: reaction temperature > B: current intensity. The reduction efficiency was hardly affected by current intensity, while it was increased with the increasing of reaction time and acid concentration. The reducing agent, Fe2+ an and extra free electron, acted as a reducing agent and could easily reduce hexavalent chromium to trivalent chromium at high temperatures in an acidic medium.
Effective Dye Degradation by Graphene Oxide Supported Manganese Oxide
Hayarpi Saroyan, George Z. Kyzas, Eleni A. Deliyanni
April 15, 2019 (v1)
Keywords: characterization, degradation, dyes, graphene oxide, manganese oxide, reuse
Graphene oxide (GO) was used as a support for manganese oxide (MnO₂) for the preparation of a nanocomposite catalyst for the degradation of an azo dye, Reactive Black 5 (RB5). The nanocomposite was characterized for the structure by XRD, for the morphology with SEM, and for the surface chemistry with FTIR and potentiometric titration measurements. The GO-MnO₂ nanocomposite presented a high catalytic activity for the degradation/oxidation of RB5 at ambient conditions, which was higher than that of the pure MnO₂ and could be attributed to the beneficial contribution of the manganese oxide and the graphene oxide.
Catastrophic Health Expenditures and Its Inequality in Households with Cancer Patients: A Panel Study
Munjae Lee, Kichan Yoon
April 15, 2019 (v1)
Subject: Biosystems
Keywords: cancer patient households, catastrophic health expenditure, healthcare spending, Korea Health Panel, panel logit analysis
This study aims to examine the determinants of catastrophic health expenditure in households with cancer patients by conducting a panel analysis of three-year data. Data are adopted from surveys administered by Korea Health Panel for 2012⁻2014. We conducted correspondence and conditional transition probability analyses to examine households that incurred catastrophic health expenditure, followed by a panel logit analysis. The analyses reveal three notable results. First, the occurrence of catastrophic health expenditure differs by age group, that is, the probability of incurring catastrophic health expenditure increases with age. Second, this probability is higher in households with National Health Insurance than those receiving medical care benefits. Finally, households without private health insurance report a higher occurrence rate. The findings suggest that elderly people with cancer have greater medical coverage and healthcare needs. Private health insurance contributes toward pro... [more]
Model-Based Stochastic Fault Detection and Diagnosis of Lithium-Ion Batteries
Jeongeun Son, Yuncheng Du
April 15, 2019 (v1)
Keywords: fault detection and classification, lithium-ion battery, Optimization, polynomial chaos expansion, thermal management, uncertainty analysis
The Lithium-ion battery (Li-ion) has become the dominant energy storage solution in many applications, such as hybrid electric and electric vehicles, due to its higher energy density and longer life cycle. For these applications, the battery should perform reliably and pose no safety threats. However, the performance of Li-ion batteries can be affected by abnormal thermal behaviors, defined as faults. It is essential to develop a reliable thermal management system to accurately predict and monitor thermal behavior of a Li-ion battery. Using the first-principle models of batteries, this work presents a stochastic fault detection and diagnosis (FDD) algorithm to identify two particular faults in Li-ion battery cells, using easily measured quantities such as temperatures. In addition, models used for FDD are typically derived from the underlying physical phenomena. To make a model tractable and useful, it is common to make simplifications during the development of the model, which may con... [more]
Multiscale Agent-Based and Hybrid Modeling of the Tumor Immune Microenvironment
Kerri-Ann Norton, Chang Gong, Samira Jamalian, Aleksander S. Popel
April 15, 2019 (v1)
Subject: Biosystems
Keywords: computational biology, immune checkpoint inhibitor, immuno-oncology, immunotherapy, mathematical modeling, multiscale systems biology, quantitative systems pharmacology (QSP)
Multiscale systems biology and systems pharmacology are powerful methodologies that are playing increasingly important roles in understanding the fundamental mechanisms of biological phenomena and in clinical applications. In this review, we summarize the state of the art in the applications of agent-based models (ABM) and hybrid modeling to the tumor immune microenvironment and cancer immune response, including immunotherapy. Heterogeneity is a hallmark of cancer; tumor heterogeneity at the molecular, cellular, and tissue scales is a major determinant of metastasis, drug resistance, and low response rate to molecular targeted therapies and immunotherapies. Agent-based modeling is an effective methodology to obtain and understand quantitative characteristics of these processes and to propose clinical solutions aimed at overcoming the current obstacles in cancer treatment. We review models focusing on intra-tumor heterogeneity, particularly on interactions between cancer cells and strom... [more]
Revolution 4.0: Industry vs. Agriculture in a Future Development for SMEs
Ilaria Zambon, Massimo Cecchini, Gianluca Egidi, Maria Grazia Saporito, Andrea Colantoni
April 15, 2019 (v1)
Subject: Energy Policy
Keywords: agriculture 4.0, application research, Industry 4.0, open source, SMEs, Supply Chain
The present review retraces the steps of the industrial and agriculture revolution that have taken place up to the present day, giving ideas and considerations for the future. This paper analyses the specific challenges facing agriculture along the farming supply chain to permit the operative implementation of Industry 4.0 guidelines. The subsequent scientific value is an investigation of how Industry 4.0 approaches can be improved and be pertinent to the agricultural sector. However, industry is progressing at a much faster rate than agriculture. In fact, already today experts talk about Industry 5.0. On the other hand, the 4.0 revolution in agriculture is still limited to a few innovative firms. For this reason, this work deals with how technological development affects different sectors (industry and agriculture) in different ways. In this innovative background, despite the advantages of industry or agriculture 4.0 for large enterprises, small- and medium-sized enterprises (SMEs) of... [more]
The Effect of the Presence of Very Cohesive Geldart C Ultra-Fine Particles on the Fluidization of Geldart A Fine Particle Beds
Abbas Kamranian Marnani, Andreas Bück, Sergiy Antonyuk, Berend van Wachem, Dominique Thévenin, Jürgen Tomas
April 15, 2019 (v1)
Subject: Materials
Keywords: agglomeration, binary mixtures, cohesion, fine particle, fluidization, ultra-fine powders
The effect of the presence of ultra-fines (d < 10 μm) on the fluidization of a bed containing fine particles (d < 100 μm), is the subject of this paper. Practically, it can happen due to breakage or surface abrasion of the fine particles in some processes which totally changes the size distribution and also fluidization behaviour. The materials used in this study are both ground calcium carbonate (GCC); fine is CALCIT MVT 100 (Geldart’s group A) and ultra-fine is CALCIT MX 10 (group C). The experimental results for different binary mixtures of these materials (ultra-fines have 30%, 50%, or 68% of the total mixture weight) show that the physical properties of the mixtures are close to those of pure ultra-fine powders. Using mean values of the bed pressure drop calculated from several independent repetitions, the fluidization behaviour of different mixtures are compared and discussed. The fluidization behaviour of the mixtures is non-reproducible and includes cracking, channelling... [more]
Textile Wastewater Treatment for Water Reuse: A Case Study
Hua Yin, Peiwen Qiu, Yuange Qian, Zhuwen Kong, Xiaolong Zheng, Zhihua Tang, Huafang Guo
April 15, 2019 (v1)
Keywords: ozonation, reverse osmosis, textile wastewater, ultrafiltration, water recovery rate, water reuse
The reduced natural waters and the large amount of wastewater produced by textile industry necessitate an effective water reuse treatment. In this study, a combined two-stage water reuse treatment was established to enhance the quality and recovery rate of reused water. The primary treatment incorporated a flocculation and sedimentation system, two sand filtration units, an ozonation unit, an ultrafiltration (UF) system, and a reverse osmosis (RO) system. The second treatment included an ozonation unit, a sand filtration unit, and UF and RO systems. The color removal rate increased with the increasing ozone dosage, and the relational expression between the ozone dosage and color removal rate was fitted. Ozonation greatly reduced the color by 92.59 and 97.27 times during the primary and second ozonation stages, respectively. RO had the highest removal rate. The combined processes showed good performance in water reuse treatment. The treated, reused water satisfied the reuse standard and... [more]
Mixing Efficiency Analysis on Droplet Formation Process in Microchannels by Numerical Methods
Jin-yuan Qian, Xiao-juan Li, Zhi-xin Gao, Zhi-jiang Jin
April 15, 2019 (v1)
Keywords: disperse phase fraction, junction configuration, mixing efficiency, VOF method
Liquid⁻liquid two-phase flow in microchannels has attracted much attention, due to the superiority of mass transfer enhancement. One of the biggest unresolved challenges is the low mixing efficiency at the microscale. Suitable mixing efficiency is important to promote the mass transfer of two-phase flow in microchannels. In this paper, the mixing efficiency in three junction configurations, including a cross-shaped junction, a cross-shaped T-junction, and a T-junction, is investigated by the volume of fluid (VOF) method coupled with user-defined scalar (UDS) model. All three junction configurations are designed with the same hydraulic diameter of 100 μm. Mixing components are distributed in the front and back parts of the droplet. The mixing efficiency in the droplet forming stage and the droplet moving stage are compared quantitatively. Results show that different junction configurations create very different mixing efficiencies, and the cross-shaped T-junction performs best, with rel... [more]
Acknowledgement to Reviewers of Processes in 2018
Processes Editorial Office
April 15, 2019 (v1)
Subject: Other
Rigorous peer-review is the corner-stone of high-quality academic publishing [...]
Multi-Tubular Reactor for Hydrogen Production: CFD Thermal Design and Experimental Testing
Elvira Tapia, Aurelio González-Pardo, Alfredo Iranzo, Manuel Romero, José González-Aguilar, Alfonso Vidal, Mariana Martín-Betancourt, Felipe Rosa
April 15, 2019 (v1)
Keywords: Computational Fluid Dynamics, Computational Fluid Dynamics, hydrogen production, model, solar reactor, solar receiver, thermal energy
This study presents the Computational Fluid Dynamics (CFD) thermal design and experimental tests results for a multi-tubular solar reactor for hydrogen production based on the ferrite thermochemical cycle in a pilot plant in the Plataforma Solar de Almería (PSA). The methodology followed for the solar reactor design is described, as well as the experimental tests carried out during the testing campaign and characterization of the reactor. The CFD model developed for the thermal design of the solar reactor has been validated against the experimental measurements, with a temperature error ranging from 1% to around 10% depending on the location within the reactor. The thermal balance in the reactor (cavity and tubes) has been also solved by the CFD model, showing a 7.9% thermal efficiency of the reactor. CFD results also show the percentage of reacting media inside the tubes which achieve the required temperature for the endothermic reaction process, with 90% of the ferrite pellets inside... [more]
Ultrasonic-Assisted Extraction and Swarm Intelligence for Calculating Optimum Values of Obtaining Boric Acid from Tincal Mineral
Bahdisen Gezer, Utku Kose
April 15, 2019 (v1)
Keywords: Artificial Intelligence, boric acid, central composite design, Optimization, swarm intelligence, tincal, ultrasound assisted extraction
The objective of this study is to focus on boric acid extraction from the mineral tincal, in order to determine the optimum conditions thanks to the ultrasonic-assisted extraction (UAE) technique (with the response surface methodology (RSM) for the first time), and artificial intelligence based swarm intelligence. Characterization of the tincal were done by using thermo-gravimetric assay (TG-DTA), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses. In detail, a central composite design (CCD) was used for determining the effects of different solvent/solid ratios, pH, extraction time, and extraction temperature on the yield, which was determined by the conductometric method. The optimum values regarding the best extraction process was calculated by using five different swarm intelligence techniques: Particle swarm optimization (PSO), cuckoo search (CS), genetic algorithms (GA), Differential evolution (DE), and the vortex optimization algorithm (VOA). In... [more]
Ambient Pressure-Dried Graphene⁻Composite Carbon Aerogel for Capacitive Deionization
Chen Zhang, Xiaodong Wang, Hongqiang Wang, Xueling Wu, Jun Shen
April 15, 2019 (v1)
Subject: Other
Keywords: capacitive deionization, desalination, electrosorption, graphene–composite carbon aerogel (GCCA)
Capacitive deionization (CDI) technology possessing excellent desalination performance and energy efficiency is currently being widely studied in seawater desalination. In this work, the graphene⁻composite carbon aerogels (GCCAs) easily prepared by an ambient pressure drying method served as electrodes to remove salt ions in aqueous solution by CDI. The microstructure of the obtained GCCAs was found to depend on the component content in the precursor solution, and could be controlled through varying the mass ratio of resorcinol and formaldehyde to graphene oxide (RF/GO). The surface characteristics and microstructure of GCCAs were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). In addition, the electrochemical tests and CDI experiments of GCCA electrodes were conducted in NaCl solution. Thanks to the reasonable pore structure and highly conductive network, GCCA-150 achieved the best salt adsorption capacity of 26.9 mg/... [more]
Numerical Investigation of Hydraulic Fracture Propagation Based on Cohesive Zone Model in Naturally Fractured Formations
Jianxiong Li, Shiming Dong, Wen Hua, Xiaolong Li, Xin Pan
April 15, 2019 (v1)
Subject: Other
Keywords: hydraulic fractures, multitude parameters, naturally fracture, PPCZ, propagation pattern, stress interference
Complex propagation patterns of hydraulic fractures often play important roles in naturally fractured formations due to complex mechanisms. Therefore, understanding propagation patterns and the geometry of fractures is essential for hydraulic fracturing design. In this work, a seepage⁻stress⁻damage coupled model based on the finite pore pressure cohesive zone (PPCZ) method was developed to investigate hydraulic fracture propagation behavior in a naturally fractured reservoir. Compared with the traditional finite element method, the coupled model with global insertion cohesive elements realizes arbitrary propagation of fluid-driven fractures. Numerical simulations of multiple-cluster hydraulic fracturing were carried out to investigate the sensitivities of a multitude of parameters. The results reveal that stress interference from multiple-clusters is responsible for serious suppression and diversion of the fracture network. A lower stress difference benefits the fracture network and he... [more]
Robust Scheduling Optimization Model for Multi-Energy Interdependent System Based on Energy Storage Technology and Ground-Source Heat Pump
Zhongfu Tan, Hongwu Guo, Hongyu Lin, Qingkun Tan, Shenbo Yang, De Gejirifu, Liwei Ju, Xueying Song
April 15, 2019 (v1)
Keywords: distributed energy, Energy Storage, ground-source heat pump, PSO algorithm, robust scheduling optimization
The energy consumed by buildings makes up a significant part of total social energy consumption. The energy use rate of the traditional cooling and heating unit is low. A distributed cooling, heating, and power (CHP) system can achieve cascade use of energy and reduce the long-distance transportation of energy. Along with the wide use of ground-source heat pumps and energy storage technology, the combined cooling, heating, and power (CCHP) system coupled with a ground-source heat pump and energy storage technology is increasingly being used. Firstly, we proposed the construction of a CCHP system driven by distributed energy resources (DERs) including three subsystems of an electricity subsystem, a CCHP subsystem and an auxiliary heating subsystem as the object of study in this paper. Besides, with the goals of reducing carbon emissions, increasing energy efficiency, and minimizing system cost, a constraint mechanism based on the DOM-PSO (dynamic object method/particle swarm optimizatio... [more]
Modeling/Simulation of the Dividing Wall Column by Using the Rigorous Model
Chi Zhai, Qinjun Liu, Jose A. Romagnoli, Wei Sun
April 15, 2019 (v1)
Keywords: gProms, rigorous DWC model, the benzene–toluene–xylene system
Dividing wall column (DWC) is an atypical distillation column with an internal, vertical WE partition wall that effectively accommodates two conventional distillation columns into one to improve the thermodynamic efficiency. In previous studies, different equivalent models by combining conventional columns are adopted to approximate the DWC modeling, which may not well describe the integration of the DWC; moreover, the computational cost increases when multiple columns are implemented to represent one DWC. In this paper, a rigorous mathematical model is proposed based on the mass balance, the energy and phase equilibrium of the DWC, where decision variables and state variables are equally treated. The model was developed in the general process modeling system (gPROMS). Based on the rigorous model, the influences of liquid split ratio and vapor split ratio are discussed, and it is shown that the heat duty is sensitive to changes on the liquid and vapor split ratio. Inappropriate liquid... [more]
Integration Multi-Model to Evaluate the Impact of Surface Water Quality on City Sustainability: A Case from Maanshan City in China
Zhanbo Chen, Hui Zhang, Mingxia Liao
April 15, 2019 (v1)
Subject: Energy Policy
Keywords: ensemble learning, MCDM, multi-model evaluation, water pollution
Water pollution is a worldwide problem that needs to be solved urgently and has a significant impact on the efficiency of sustainable cities. The evaluation of water pollution is a Multiple Criteria Decision-Making (MCDM) problem and using a MCDM model can help control water pollution and protect human health. However, different evaluation methods may obtain different results. How to effectively coordinate them to obtain a consensus result is the main aim of this work. The purpose of this article is to develop an ensemble learning evaluation method based on the concept of water quality to help policy-makers better evaluate surface water quality. A valid application is conducted to illustrate the use of the model for the surface water quality evaluation problem, thus demonstrating the effectiveness and feasibility of the proposed model.
Combining Microwave Pretreatment with Iron Oxide Nanoparticles Enhanced Biogas and Hydrogen Yield from Green Algae
Asad A. Zaidi, Ruizhe Feng, Adil Malik, Sohaib Z. Khan, Yue Shi, Asad J. Bhutta, Ahmer H. Shah
April 15, 2019 (v1)
Subject: Biosystems
Keywords: algae, anaerobic digestion, biogas, biohydrogen, energy assessment, kinetic models, microwave, nanoparticles, pretreatment
The available energy can be effectively upgraded by adopting smart energy conversion measures. The biodegradability of biomass can be improved by employing pretreatment techniques; however, such methods result in reduced energy efficiency. In this study, microwave (MW) irradiation is used for green algae (Enteromorpha) pretreatment in combination with iron oxide nanoparticles (NPs) which act as a heterogeneous catalyst during anaerobic digestion process for biogas enhancement. Batch-wise anaerobic digestion was carried out. The results showed that MW pretreatment and its combination with Fe₃O₄ NPs produced highest yields of biogas and hydrogen as compared to the individual ones and control. The biogas amount and hydrogen % v/v achieved by MW pretreatment + Fe₃O₄ NPs group were 328 mL and 51.5%, respectively. The energy analysis indicated that synergistic application of MW pretreatment with Fe₃O₄ NPs produced added energy while consuming less input energy than MW pretreatment alone. The... [more]
Building Block-Based Synthesis and Intensification of Work-Heat Exchanger Networks (WHENS)
Jianping Li, Salih Emre Demirel, M. M. Faruque Hasan
April 15, 2019 (v1)
Keywords: building blocks, MINLP, superstructure, WHENS, work and heat integration
We provide a new method to represent all potential flowsheet configurations for the superstructure-based simultaneous synthesis of work and heat exchanger networks (WHENS). The new representation is based on only two fundamental elements of abstract building blocks. The first design element is the block interior that is used to represent splitting, mixing, utility cooling, and utility heating of individual streams. The second design element is the shared boundaries between adjacent blocks that permit inter-stream heat and work transfer and integration. A semi-restricted boundary represents expansion/compression of streams connected to either common (integrated) or dedicated (utility) shafts. A completely restricted boundary with a temperature gradient across it represents inter-stream heat integration. The blocks interact with each other via mass and energy flows through the boundaries when assembled in a two-dimensional grid-like superstructure. Through observation and examples from l... [more]
Chemical Recycling of Used Printed Circuit Board Scraps: Recovery and Utilization of Organic Products
Se-Ra Shin, Van Dung Mai, Dai-Soo Lee
April 15, 2019 (v1)
Subject: Other
Keywords: chemical recycling, glycolysis, recycled polyol, rigid polyurethane foam, used printed circuit board
The disposal of end-of-life printed circuit boards (PCBs) comprising cross-linked brominated epoxy resins, glass fiber, and metals has attracted considerable attention from the environmental aspect. In this study, valuable resources, especially organic material, were recovered by the effective chemical recycling of PCBs. Pulverized PCB was depolymerized by glycolysis using polyethylene glycol (PEG 200) with a molecular weight of 200 g/mol under basic conditions. The cross-linked epoxy resins were effectively decomposed into a low-molecular species by glycolysis with PEG 200, followed by the effective separation of the metals and glass fibers from organic materials. The organic material was modified into recycled polyol with an appropriate viscosity and a hydroxyl value for rigid polyurethane foams (RPUFs) by the Mannich reaction and the addition polymerization of propylene oxide. RPUFs prepared using the recycled polyol exhibited superior thermal and mechanical properties as well as th... [more]
Model for Thin Layer Drying of Lemongrass (Cymbopogon citratus) by Hot Air
Thi Van Linh Nguyen, My Duyen Nguyen, Duy Chinh Nguyen, Long Giang Bach, Tri Duc Lam
April 15, 2019 (v1)
Subject: Biosystems
Keywords: activation energy, convection drying, Cymbopogon citratus, lemongrass, mathematical modeling, moisture diffusivity
Lemongrass is a plant that contains aromatic compounds (myrcene and limonene), powerful deodorants, and antimicrobial compounds (citral and geraniol). Identifying a suitable drying model for the material is crucial for establishing an initial step for the development of dried products. Convection drying is a commonly used drying method that could extend the shelf life of the product. In this study, a suitable kinetic model for the drying process was determined by fitting moisture data corresponding to four different temperature levels: 50, 55, 60 and 65 °C. In addition, the effect of drying temperature on the moisture removal rate, the effective diffusion coefficient and activation energy were also estimated. The results showed that time for moisture removal increases proportionally with the air-drying temperature, and that the Weibull model is the most suitable model for describing the drying process. The effective diffusion coefficient ranges from 7.64 × 10−11 m²/s to 1.48 × 10−10 m²... [more]
Showing records 101 to 125 of 203. [First] Page: 1 2 3 4 5 6 7 8 9 Last