Renewable Energy Global Innovations features: Solid-binding peptides for immobilization of thermostable enzymes to hydrolyze biomass polysaccharides

Significance Statement

Immobilization of enzymes onto solid supports can be achieved by a number of physical and chemical methods including, covalent attachment, adsorption, crosslinking and encapsulation. Immobilized enzymes, as opposed to soluble enzymes, offer better stability and easier removal from reaction mixtures, enabling repetitive use in batch and continuous bioprocesses and rapid termination of reactions.

Unfortunately, typical enzyme immobilization approaches usually result in a non-uniform orientation of the enzyme as well as unwanted conformational changes that alter their active sites and may curtail the catalytic activity of the enzyme. Solid-binding peptides have binding affinity as well as selectivity to the surfaces of solid materials such as glass, polymers, silica, metals and zeolite, all support materials employed with biocatalysts.

Solid-binding peptides typically are used as molecular linkers for functional protein immobilization onto solid surfaces without the need for any chemical reactions or even physical treatments.

Researchers led by Professor Anwar Sunna at Macquarie University in Australia have presented the implementation of the solid-binding peptide-mediated immobilization of industrially-based enzymes onto a low cost solid zeolite matrix. The introduction of crosslinking of the immobilized enzymes to create single as well as multiple enzyme biocatalytic modules enabled the authors to highlight the feasibility of this technology for its integration in industrial-scale processes. Their work is published in Biotechnology for Biofuels.

The research team genetically fused the silica-binding linker peptide to three thermostable polysaccharide-degrading enzymes for potential application in industrial-scale biocatalysis. The linker had significant affinity for silica-containing supports allowing for directional immobilization of these enzymes onto the zeolite matrix. The enzymes were observed to retain their binding affinity for zeolite and their biological activity. The integration of the linker did not have adverse effects on the pH and temperature optima of the polysaccharide-degrading enzymes and the assembled single and multiple enzyme biocatalytic modules retained their specific hydrolytic activities upon several rounds of recycling at high temperatures.

Professor Sunna summarized the importance of this platform technology saying; “Despite the promising characteristics of solid-binding peptides, their practical application has been mostly in nanobiotechnology, where immobilization of biomolecules generally relies on exotic and expensive laboratory-based matrices that may not be realistic economically for large-scale processes. Inorganic bulk materials like zeolite and silica are excellent carriers due to their structural and operational stability and their lack of susceptibility to microbial degradation. The combination of solid-binding ability and low-cost bulk materials represents an ideal technology for production of industrial-scale biocatalysts.”

The linker system developed in their study minimizes the time wasted in choosing precipitants as well as crosslinking reagents. Its compositional and structural characteristics allows it to impart orientation and directionality to enzymes after crosslinking. This combination results in improved enzyme reusability. Therefore, this linker technology presents an inexpensive immobilization approach for industrially based enzymes.

About The Author

Andrew Care is a Research Fellow in the ARC Centre of Excellence for Nanoscale BioPhotonics, a transdisciplinary research centre that aims to develop innovative nanotechnologies to investigate complex living systems. He obtained his PhD from Macquarie University in Sydney, Australia.

His current research is focused on the use of solid-binding peptides to control the immobilization of proteins and enzymes onto solid matrices in a range of biotechnological applications, including biocatalysis.

About The Author

Kerstin Petroll obtained her Diploma degree in Food Chemistry at the Karlsruhe Institute of Technology (KIT) in Germany. She was awarded a Macquarie University Research Excellence Scholarship to join Macquarie University as a postgraduate student in 2015. Initially, she focused on analytical sciences of plant metabolites and proteins for medical applications before changing to the field of synthetic biology with a focus on environmental applications. Her PhD project aims at the assembly of a cell-free synthetic pathway to produce a platform chemical from renewable low-value compounds.

About The Author

Peter Bergquist is Emeritus Professor in the Biomolecular Discovery and Design Research Centre at Macquarie University. He has a PhD and DSc from the University of Auckland in New Zealand and has been a Postdoctoral Fellow and Research Fellow at Harvard Medical School, Yale and Oxford Universities and a Visiting Fellow at New York University School of Medicine.

He is one of the pioneers of cloning and expressing genes from extremely thermophilic bacteria. He has an interest in biofuels that stems from early studies of cellulolytic microorganisms and their enzymes for biomass breakdown. He has been on the editorial boards of several significant journals such as Applied and Environmental Microbiology and Journal of Bacteriology.

About The Author

Anwar Sunna is an Associate Professor in Synthetic Biology in the Department of Chemistry and Biomolecular Sciences at Macquarie University (MQ), Sydney, Australia. He obtained a PhD from the Hamburg University of Technology in Germany. He was manager of the Environmental Biotechnology Co-operative Research Centre at MQ and later was the recipient of the prestigious Vice-Chancellor’s Innovation Fellowship.

His recent research has been on the interaction between biomolecules and inorganic compounds including new synthetic peptide linkers with applications in enzyme immobilisation and functionalisation of nanomaterials. Anwar is a member of the MQ Biomolecular Discovery and Design Research Centre, MQ Biosecurity Futures Research Centre, Australian Research Council (ARC) Training Centre for Molecular Technology in the Food Industry and the ARC Centre of Excellence for Nanoscale BioPhotonics. He is also one of the directors of Synthetic Biology Australasia.

Reference

Andrew Care, Kerstin Petroll, Emily S. Y. Gibson, Peter L. Bergquist, and Anwar Sunna. Solid-binding peptides for immobilization of thermostable enzymes to hydrolyze biomass polysaccharides. Biotechnol Biofuels (2017) 10:29.

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Renewable Energy Global Innovations features: Graphene oxide/WS2/Mg-doped ZnO nanocomposites for solar-light catalytic and anti-bacterial applications

Significance Statement

Semiconductor oxides find an array of applications in water purification for photocatalytic degradation of organic dyes. Zinc oxide is perhaps the most popular component for photocatalytic applications owing to its wide band gap, low cost, environmental friendliness, and large exciton binding energy leading to superior optical activity. This makes zinc oxide an important ingredient for photo catalyst for organic pollutants treatments.

However, high recombination rate of electron-hole pairs in semiconductors as well as insufficient solar spectrum absorption limit its photocatalytic reaction efficiency. Doping, constructing heterojunctions and catalyzer carrier are viewed as solutions to these problems, and are used mainly to enhance the photocatalytic activity of zinc oxide nanostructure. Doping the zinc oxide with a suitable element is an important approach for improving its sunlight absorption.

Catalyzer carrier is viewed as an effective approach for decreasing recombination rate of photo generated electron-hole pairs. Graphene is an important catalyst support, which has been deemed as the most promising building block to trap and transfer the photo-induced electrons because of its large surface area, high carrier capacity, and large electronic storage ability. Graphene can fix zinc oxide nanoparticles defects for conducting electron and function as a conducting network. It can as well prevent zinc oxide from aggregation and result in the improvement of the photocatalytic performance.

A group of researchers led by Professor Yuenhong Tsang at The Hong Kong Polytechnic University Shenzhen Research Institute demonstrated the scalable approach to fabricate large amount of tungsten disulfide Nano plates through the mechanical shear exfoliation approach. They adopted a versatile method to produce 3D reduced graphene oxide-tungsten disulfide nanosheet magnesium doped zinc oxide hybrid implementing a layer-by-layer assembly method. They achieved photocatalytic attributes enhancement adopting the 3D graphene tungsten disulfide hybrid. Their work is published in Solar Energy Materials & Solar Cells.

The authors used Rhodamine as a model dye in a bid to evaluate the photocatalytic activity of the specimens. The research team computed the degradation ratio as the quotient between original concentration and the residual concentration at varying time. After a complete degradation of the Rhodamine, the authors isolated the graphene nanocomposites and added them to a different solution with the same Rhodamine concentration. This was in a bid to analyze the photocatalytic stability of the resulting composites.

The authors observed the adsorption ability of the specimen before opening light in order to differentiate adsorption effect and photocatalytic ability of the samples for Rhodamine. They realized that the adsorption ratio of all samples for Rhodamine was less than 10% in the dark. When exposed to about 100W UV light irradiation, the group without a photo catalyst indicated about 20% photo degradation. However, a 60% photo degradation was recorded when reduced graphene oxide/magnesium doped zinc oxide composites samples were imported.

However, a 90% removed rate of reduced graphene oxide-tungsten disulfide nanosheet magnesium doped zinc oxide hybrid for Rhodamine was recorded after 5 min, and the Rhodeamine was completely removed after 10min.

Inhibition rings sizes against E, coli as well as S. aureus were 8.64mm and 6.07mm respectively for magnesium doped zinc oxide specimen.  However, when graphene was introduced, the rings sizes increased to 9.23mm and 10.21mm.

Tungsten disulfide nanosheet played a critical role in improving photocatalytic and antibacterial activity of the magnesium-doped zinc oxide composite. The outcomes of the study prove that the resulting 3-D tungsten doped zinc oxide composites could be good candidates for sunlight-driven photocatalytic, self-cleaning, environmental protecting, and photovoltaic applications.

About The Author

Dr. Yuen Hong Tsang has completed his undergraduate and PhD study in the School of Physics and Astronomy, The University of Manchester, UK in 2004. He came back to Hong Kong in 2009 and he is now Assistant Professor in Applied Physics Department, The Hong Kong Polytechnic University. He has published >100 SCI international peer reviewed journals with H-index >20 and total citation >1400.

His current research interests include development of novel materials, e.g. graphene, MoS₂, WS₂ etc. for laser photonics, photo-catalysis, solar energy conversion applications, e.g. photo-catalyst, solar heat absorber, saturable absorber, optical limiter, photo detection, fiber laser, Q-switched and mode locked lasers, etc. He has involved and successfully completed several research projects funded by some well-known international companies.

These projects include 1.  Laser range funder for military applications (funded by Thales.) 2. Imaging system for dental applications (funded by Colgate Palmolive) 3. Narrow linewidth tunable lasers (funded by Huawei) 4. Carbon based mode locking laser system (funded by Fianium Asian Ltd.)

Reference

Chuansheng Chen, Weiwei Yu, Tiangui Liu, Shiyi Cao, Yuenhong Tsang. Graphene oxide/WS2/Mg-doped ZnO nanocomposites for solar-light catalytic and anti-bacterial applications. Solar Energy Materials & Solar Cells, volume 160 (2017), pages 43–53.

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Renewable Energy Global Innovations features: Enhanced lifetime of organic photovoltaic diodes utilizing a ternary blend including an insulating polymer

Significance Statement

Organic photovoltaic diodes appear to be a promising technology because of their potential use in synthesizing low-cost, flexible, large area and lightweight electronics. Unfortunately, the limited lifetime of organic photovoltaic diodes hinders their commercialization. For example, a thousand hours lifetime reported for poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester solar cells is inferior to that of silicon photovoltaics whose lifetime extends up to 25 years.

The degradation of these solar cells remains a limitation and many researchers are still looking for ways to improve their performance. Organic photovoltaic diodes degrade owing to chemical and physical processes. Chemical degradation results from oxygen, light, water and temperature. However, water and oxygen are considered the principle factors; these oxidize the organic photovoltaic materials as well as electrodes leading to poor performance and electronic traps.  Degradation may also result from the bulk heterojunction morphology since the constituent materials may aggregate with time, leading to reduced exciton dissociation and poor performance.

Blending the active semiconductor with an inert polymer appears to improve the lifetime of the organic photovoltaic diodes. A team of researchers under the guidance of Professors Chris Groves and Michael Petty at Durham University in United Kingdom investigated the use of an insulating polymer, poly(methyl methacrylate), as a ternary component in poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester solar cells as a way of enhancing their lifetime and reducing degradation. Their research work is now published in Solar Energy Materials & Solar Cells.

The authors separately prepared poly(3-hexylthiophene) and phenyl-C61-butyric acid methyl ester solutions before mixing in a 1:1 weight ratio. In a bid to make the ternary blend, they first prepared poly(methyl methacrylate) solution by dissolving in anhydrous 1,2-dichlorobenzene to obtain a clear solution.

The authors stirred both the ternary and binary organic photovoltaic blends before spin coating them onto the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate). They annealed all devices before lifetime tests.

The research team observed that the addition of poly(methyl methacrylate) improved both the initial performance as well as the lifetime of the solar cells. Measurement of the different relative humidity values suggested that poly(methyl methacrylate) absorbed water, thereby reducing the rate of chemical degradation in the solar cell. The lifetime improvement with poly(methyl methacrylate) reduced with decreasing humidity. This suggested that the poly(methyl methacrylate) becomes saturated. A number of studies revealed that the addition of poly(methyl methacrylate) led to a morphology containing poly(methyl methacrylate) pillars dissimilar to the morphology seen in the binary film.

Electrical conductivity did not degrade at different rates across the ternary film. This suggested that water diffused microns through the film before reacting with the active material. The rate of conductivity degradation was similar for binary and ternary devices. This indicated that various degradation mechanism were present, and that poly(methyl methacrylate) only assisted in extending the lifetime associated with a selected degradation pathways.

Power conversion efficiency of the poly(3-hexylthiophene): phenyl-C61-butyric acid methyl ester solar cells is severely limited by reaction with water. The incorporation poly(methyl methacrylate) slows down this degradation process through water absorption. The results of their study suggest that electrically inert and hydroscopic polymers can be blended with an organic photovoltaic active layer to extend the device lifespan.

The addition of PMMA to a P3HT:PCBM solar cell slows down the device degradation. Left: Power conversion efficiency (PCE) as a function of time for binary P3HT:PCBM (1:1) blend and ternary (1:1:0.3) P3HT:PCBM:PMMA blend solar cells, stored at a relative humidity (RH) level of 1%. Right: AFM topography image of as-deposited (1:1:0.3) ternary P3HT:PCBM:PMMA blend film. The PMMA is in the form of circular islands.

About The Author

Mrs Zakiya AL-Busaidi received her M.Sc. degree in physics at Sultan Qaboos University, Oman.  She is currently a PhD student in the School of Engineering and Computing Sciences, Durham University, UK. Her current research focuses on how to enhance the lifetime of organic photovoltaics by using insulating polymers.

About The Author

Dr Chris Groves is an Associate Professor at the School of Engineering and Computing Sciences at Durham University, UK, where he is also a Director of the Durham Centre for Molecular and Nanoscale Electronics. He completed his PhD on III-V photodetectors at Sheffield University in 2004, before undertaking postdoctoral positions in the field of organic electronics at the Cavendish Laboratory and the University of Washington.

His research interests focus on the use of experiment and simulation to examine the relationship between charge transport and the performance of electronic devices. Recently, this has involved the development of Monte Carlo models and experimental techniques to reveal how morphology influences charge transport, and ultimately performance, in organic photovoltaic diodes.

About The Author

Dr Christopher Pearson received the Degree in Physical Electronics from Newcastle Polytechnic, Newcastle, UK, and a PhD, focusing on thin films of organic charge-transfer materials, from Durham University, Durham, UK, in 1997. Since 1981, he has been working at the University of Durham. Currently, he is an Experimental Officer with the Durham Centre for Molecular and Nanoscale Electronics, providing support for the group and carrying out research on organic thin films prepared using a variety of techniques.

About The Author

Professor Michael Petty’s higher education was at Sussex University, UK (BSc and DSc) and Imperial College, London (PhD Electronic Materials.) He has been at Durham University, UK since 1976 progressing to Professor in 1994, then Chairman of the School of Engineering from 1997 to 2000.

His research activities focus on the properties of thin films of organic materials (Langmuir-Blodgett, self-assembled, electrostatically deposited, evaporated). He has a special interest in the application of these layers to electronic and opto-electronic devices. Professor Petty has lectured extensively worldwide and published over 400 papers/books/patents in these subjects.

He is a member of Durham University Centre for Molecular and Nanoscale Electronics

Reference

Zakiya AL-Busaidi, Christopher Pearson, Christopher Groves, Michael C. Petty. Enhanced lifetime of organic photovoltaic diodes utilizing a ternary blend including an insulating polymer. Solar Energy Materials & Solar Cells, volume 160 (2017), pages 101–106.

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Renewable Energy Global Innovations features: Performance of mixed LED light wavelengths on biogas upgrade and biogas fluid removal by microalga Chlorella sp.

Significance Statement

Biogas is the most important renewable energy resource that attracts attention all around the world. In Europe, the biogas production increases from 1.18 million MMBtu d^-1 in 2010 to 1.46 million MMBtu d^-1 in 2013, while the total biogas potential is estimated as 16 million MMBtu d^-1. In China, the biogas production of small scale projects raises from 180 million m³ in 1996 to 1000 m³ in 2007, and the medium and large scale biogas projects raises from 12 billion m³ in 1996 to 600 billion m³ in 2007.

Raw biogas usually consists of methane (CH₄, approximately 60 vol. %), carbon dioxide (CO₂, approximately 40 vol. %), and other trace compositions including hydrogen sulfide (H₂S), water vapor, etc. However, the relatively high concentration of CO₂ in raw biogas will lower its heat content as well as increase its energy demand of compression and transportation usage. The biogas upgrading is removing CO₂ from raw biogas. It is the precondition for biogas high efficient usage. When the CO₂ content in the biogas is decreased, the CH₄ concentration in the biogas is increased. The biogas CH₄ concentration should be upgraded to at least higher than 90% (vol. %) to meet the criterion for using as fuel for vehicles or even substitute for natural gas.

There are several biogas upgrading techniques that have been widely applied nowadays, including absorption of liquids with physics/chemical adsorbent, membranes separation, pressure swing adsorption, and cryogenic separation. However, they usually need high capital cost when build construction and consume a large amount of energy during treating process. This makes above mentioned techniques achieve high economic benefit only when they are used in large-scale industrial biogas projects. Most of these techniques also require complicated operating systems, and produce unwanted end products that need further treatment or result in secondary pollution. Further, the CO₂, which removed from the raw biogas, is always discharged into the atmosphere as greenhouse gas in these techniques. In addition, most physical/chemical technologies for CO₂ removal require a prior removal of H₂S.

An alternative technique to upgrade biogas is to use photosynthetic CO₂ uptake by microalgae. Microalgae have high carbon fixation ability and rapid growth rate, and can be adapted to various environmental conditions. When microalgae are utilized for biogas upgrading, the photosynthesis can efficiently convert CO₂ in raw biogas into its biomass. This allows the valorization of biogas CO₂ in the form of a valuable microalgae biomass, which can be used as feedstock to produce biofuels or even high value-added by-product. Anaerobic digestion not only produce raw biogas, but also nutrient-rich waste stream, called biogas slurry, which can be uptake freely during microalgae growth process and made the major contribution to the nitrogen and phosphorus removal from biogas slurry wastewater. Therefore, removing CO₂ from raw biogas by culturing microalgae with biogas slurry is a highly potential technique for simultaneous biogas upgrading and biogas slurry decontamination.

However, as far as we know, there is a little literature available about the simultaneously biogas upgrading and biogas slurry decontamination by using of the photosynthetic CO₂ uptake of microalgae, particularly about its effects under various light intensities and wavelengths. Therefore, this research focused on the effects of various LED artificial light source’s light wavelengths, light intensities, and photoperiods on biogas upgrading and simultaneously biogas slurry decontamination by using of microalgae photo bioreactor. Furthermore, the most appropriate light wavelength was discussed. The lighting control strategy was also optimized by analyzing the microalgae growth, as well as the efficiencies of biogas CO₂ removal and simultaneously biogas slurry decontamination under various light intensities and photoperiod’s treatments.

About The Author

Associate professor Dr. Cheng YAN comes from the Department of Environmental Science and Engineering, School of Environmental Studies, China University of Geosciences (Wuhan), No. 388 Lumo Road, Hongshan District, Wuhan 430074, Hubei Province, PR China.

Dr. Cheng YAN focused on Bioenergy with Carbon Capture and Storage (BECCS). He developed several Negative Emission Technologies (NETs), which involve CO₂ capture by biological processes from diffuse and point sources, atmospheric CO₂ capture by microalgae, microalgae as bio-agent for CO₂ mitigation, and CO₂ emission valorization. He also pays close attention to optimizing microalgae photo-bioreactor with artificial lighting system, and upgrading biogas by microalgae system. The research field about purifying anaerobic fermentation slurry by microalgae is also interested.

Dr. Cheng YAN has already published 17 academic papers (10 as the first author, 1 as the second author, and other 6 as cooperator) in refereed international JCR publications in English. He is keen on academic exchanges and participated in several academic international conferences in Barcelona, Prague, Dublin, and Singapore.

Journal Reference

Applied Energy, Volume 178, 15 September 2016, Pages 9–18. 

Cheng Yan^1,2, Liandong Zhu³, Yanxin Wang²

Show Affiliations

1. Laboratory of Basin Hydrology and Wetland Eco-restoration, China University of Geosciences (Wuhan), Wuhan 430074, China
2. Department of Environmental Science and Engineering, School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan 430074, China
3. Faculty of Technology, University of Vaasa, FI65101 Vaasa, Finland

 

Abstract

Anaerobic digestion not only produces raw biogas which needs to be upgraded, but also nutrient-rich waste stream biogas slurry which needs decontamination. Therefore, this research focused on the effects of various light wavelengths, light intensities, and photoperiods on biogas upgrading and simultaneously biogas slurry decontamination by using of microalgae photobioreactor. The microalgae photobioreactor was a transparent polyethylene bag (80 cm × 60 cm × 11 cm). The results demonstrated that biogas upgrading and simultaneously biogas slurry decontamination was successfully achieved by the use of the photosynthetic CO₂ uptake by microalgae photobioreactor. The optimal light wavelength was the mixed LED red:blue = 5:5; whereas the optimized lighting control strategy was: low light intensity (300 μmol m⁻² s⁻¹) with long photoperiod (16 h light:8 h dark) for the time course of 0–48 h, moderate light intensity (600 μmol m⁻² s⁻¹) with middle photoperiod (14 h light:10 h dark) for the time course of 48–96 h, and high light intensity (900 μmol m⁻² s⁻¹) with short photoperiod (12 h light:12 h dark) for the time course of 96–144 h. Its biogas CO₂ removal efficiency was 85.46 ± 6.25%. Its removal efficiency of chemical oxygen demand, total nitrogen, and total phosphorus were 85.23 ± 8.32%, 87.10 ± 7.55%, and 92.40 ± 3.05%, respectively.

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Renewable Energy Global Innovations features: Superior Sodium Storage in Na2Ti3O7 Nanotube Arrays through Surface Engineering

Significance Statement

Sodium-ion batteries (SIBs) offer a promising scalable energy storage alternative to current lithium-ion batteries (LIBs). Titanium based SIB anode materials have attracted great interest owing to highly efficient Na storage activity, high stability, and low cost. The Na₂Ti₃O₇ structure is composed of zigzag layers of titanium oxygen octahedral, in which up to 3.5 Na ions per formula unit can be intercalated into the interlayer space and easily exchanged, leading to a capacity of 310 mAh g^–1.

This anode shows a low Na insertion potential (0.3 vs Na), leading to a higher operating voltage and energy density in practical batteries. However, the Na₂Ti₃O₇ still suffers from sluggish Na insertion/extraction kinetics resulting from a large bandgap of 3.7 eV and insufficient cycling stability for substantial Na insertion (>2 Na per unit formula) in the lattice due to the fact that the mechanical strain exists upon Na uptake and that the reactive surface sites cause unwanted electrolyte degradation and irreversible trapping of Na ions.

To attack these critical problems of reaction kinetics and surface trapping, for the first time, Prof. Liang Li’s group and their coworkers reported a novel surface engineering method by combining atomic layer deposition (ALD) and elemental doping (Adv. Energy Mater. 2016, 6, 1502568). The fabrication of the Na₂Ti₃O₇ electrode includes the hydrothermal growing of Na₂Ti₃O₇ nanotube arrays, surface ALD deposition of a thin TiO₂ layer, and subsequent sulfidation.

The nanoarrays exhibited high reversible capacities of 221 mAh g⁻¹ and a superior cycling efficiency and rate capability, retaining 78 mAh g⁻¹ at 10 C (1770 mA g⁻¹) over 10 000 continuous cycles. The full cells consisting of Na₂Ti₃O₇ nanotube anode and Na_2/3(Ni_1/3Mn_2/3)O₂ cathode deliver a specific energy of 110 Wh kg⁻¹.  

About The Author

Prof. Liang Li is a full professor in Soochow University, China. He received the Ph.D. degree from the Institute of Solid State Physics, Chinese Academy of Sciences and won the Excellent President Scholarship in 2006. From 2007-2012, he worked in National University of Singapore, Singapore, National Institute of Advanced Industrial Science and Technology, Japan, National Institute for Materials Science, Japan, and the University of Western Ontario, Canada.

Dr. Li’s research group focuses mainly on the energy conversion and storage devices of low-dimensional nanomaterials. He was awarded by China government as 1000 Youth Talents Plan and Excellent Youth Foundation in 2013 and 2014, respectively. His group web: http://ecs.suda.edu.cn  

Journal Reference

Advanced Energy Materials, 2016, Volume 6, Issue 11.

Jiangfeng Ni¹, Shidong Fu¹, Chao Wu², Yang Zhao¹, Joachim Maier², Yan Yu^2,3,4, Liang Li¹

Show Affiliations

1. College of Physics, Optoelectronics and Energy, Center for Energy Conversion Materials & Physics (CECMP), Soochow University, Suzhou, P. R. China
2. Max Planck Institute for Solid State Research, Stuttgart, Germany
3. Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, P. R. China
4. State Key Laboratory of Fire Science (SKLFS), University of Science and Technology of China, Hefei, Anhui, P. R. China 

Abstract

Sodium-ion batteries have attracted extraordinary attention owing to their low cost and raw materials in abundance. A major challenge of practical implementation is the lack of accessible and affordable anodes that can reversibly store a substantial amount of Na ions in a fast and stable manner. It is reported that surface engineered sodium titanate (Na₂Ti₃O₇) nanotube arrays directly grown on Ti substrates can serve as efficient anodes to meet those stringent requirements. The fabrication of the nanotube arrays involves hydrothermal growing of Na₂Ti₃O₇ nanotubes, surface deposition of a thin layer of TiO₂, and subsequent sulfidation.

The resulting nanoarrays exhibit a high electrochemical Na-storage activity that outperforms other Na₂Ti₃O₇ based materials. They deliver high reversible capacities of 221 mAh g⁻¹ and exhibit a superior cycling efficiency and rate capability, retaining 78 mAh g⁻¹ at 10 C (1770 mA g⁻¹) over 10 000 continuous cycles. In addition, the full cell consisting of Na₂Ti₃O₇ nanotube anode and Na_2/3(Ni_1/3Mn_2/3)O₂ cathode is capable of delivering a specific energy of ≈110 Wh kg⁻¹ (based on the mass of both electrodes). The surface engineering can provide useful tools in the development of high performance anode materials with robust power and cyclability.

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Renewable Energy Global Innovations features: Computer simulations to maximise fuel efficiency and work performance of agricultural tractors in rotovating and ploughing operations

Significance Statement

Agricultural tractor is the one of the largest fuel consumers among agricultural machines. The tractor population is growing continuously and the tractor power also appears to increase in recent years. This trend is expected to continue and so is tractors’ fuel consumption in Korea. In addition, tractors should meet emission standards both in domestic and overseas markets. In response to such circumstances, tractor manufacturers are required to develop technologies to increase fuel efficiency of tractors and at the same time to reduce their emissions without any power loss.

In order to solve this problems, automatic control system for maximizing the fuel efficiency system will be necessary in the near future. There are many techniques for maximizing the fuel efficiency of agricultural tractor using engine, transmission and implements control separately. But few studies were conducted for investigate the interaction between separated control systems. For integrating the control system, effects of each control variables on fuel efficiency were analysed.

This study was conducted to investigate the effects of five control variables of a tractor: ballast, tyre inflation pressure, transmission gear, engine speed, and work load on fuel efficiency parameters. Tractor simulation model was developed and was validated using the field experiments results. Using the Using the tractor model, 162 simulations were performed under the various combinations of the control variables on the basis of a full factorial design. The simulation results were used to develop linear regression models from which strategies can be established to maximise fuel efficiency. The best strategy reduced FC, FCA, and SVFC by 81.3, 61.1, and 52% under ploughing, and by 58.9, 75.7 and 28.6% under rotovating operations, respectively, when compared with those for the worst strategy.

      

Figure Legend: Schematic of Tractor simulation model

About The Author

Jin Woong Lee is currently a senior researcher of LSMtron Co. tractor manufacturing company at Gyeonggi-do, Korea since 2014. He is interested in the design of control algorithm and control system architecture for agricultural tractor transmission and hydraulic system. He received a B.S and MS., and a Ph. D. degrees in Biosystems Engineering from Seoul National University, Korea.

About The Author

Jae Seung Kim studied automatic gear-shift algorithm for fuel efficiency of agricultural tractors in Off-road equipment design lab. He received a B.S. and MS degrees in Biosystems Engineering from Seoul National University, Korea. Now he works in Shinho systems Co., Ltd. since 2015 and is interested in the simulation of drivetrain and vehicle dynamics.

About The Author

Kyeong Uk Kim Has been a professor of Biosystems and Biomaterial Science and Engineering at Seoul National University specializing in farm power and machinery, soil-machine systems and life test of machine components. He has co-authored several books including principle of agricultural machines. He holds a BSc and MSc in Agricultural Engineering from Seoul National University and a PhD in Agricultural Engineering from University of Illinois at Urbana-Champaign USA (1981)

Reference

Biosystems Engineering, Volume 142, 2016, Pages 1–11.

Jin W. Lee, Jae S. Kim, Kyeong U. Kim

Department of Biosystems & Biomaterials Science and Engineering, Seoul National University, Seoul 151-921, South Korea.

This study was conducted to investigate the effects of five control variables of a tractor: ballast, tyre inflation pressure, transmission gear, engine speed, and work load on three fuel efficiency parameters: fuel consumption per work hour (FC), fuel consumption per tilled area (FCA) and specific volumetric fuel consumption (SVFC). This was done for moldboard ploughing and rotovating operations by computer simulation. A tractor model was constructed with four sub-models: engine and power train, fuel consumption, tractive performance, and draught and power requirement. The simulated fuel efficiency values were in a range of 3.3–6.5% error in average when compared with those obtained from field experiments carried out in a paddy field under the same operational conditions. Based on these results, the tractor model was considered acceptable for simulations to find a general relationship between the fuel efficiency parameters and the control variables.

Using the tractor model, 162 simulations were performed under the various combinations of the control variables on the basis of a full factorial design. The simulation results were used to develop linear regression models from which strategies can be established to maximise fuel efficiency. The best strategy reduced FC, FCA, and SVFC by 81.3, 61.1, and 52% under ploughing, and by 58.9, 75.7 and 28.6% under rotovating operations, respectively, when compared with those for the worst strategy.

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