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  • 1.
    Adelholt, Martin
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Production preparations of Hydra Coupler: Preparations, Planning, Calculations2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 2.
    Adelholt, martin
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Production preparations of Hydra Coupler: Preparations, Planning, Calculations2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 3.
    Afewerki, Samson
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Córdova, Armando
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Enamine/Transition Metal Combined Catalysis: Catalytic Transformations Involving Organometallic Electrophilic Intermediates2019Inngår i: Topics in Current Chemistry, ISSN 2365-0869, Vol. 377, nr 6, artikkel-id 38Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The concept of merging enamine activation catalysis with transition metal catalysis is an important strategy, which allows for selective chemical transformations not accessible without this combination. The amine catalyst activates the carbonyl compounds through the formation of a reactive nucleophilic enamine intermediate and, in parallel, the transition metal activates a wide range of functionalities such as allylic substrates through the formation of reactive electrophilic π-allyl-metal complex. Since the first report of this strategy in 2006, considerable effort has been devoted to the successful advancement of this technology. In this chapter, these findings are highlighted and discussed. 

  • 4.
    Afewerki, Samson
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap. Stockholm University, Stockholm.
    Wang, J. -X
    Jilin University, Changchun, China.
    Liao, W. -W
    Jilin University, Changchun, China.
    Cordova, Armando
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap. Stockholm University, Stockholm.
    The Chemical Synthesis and Applications of Tropane Alkaloids2019Inngår i: Alkaloids: Chemistry and Biology, ISSN 1099-4831, Vol. 81, s. 151-233Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tropanes are an important class of alkaloid natural products that are found in plants all over the world. These compounds can exhibit significant biological activity and are among the oldest known medicines. In the early 19th century, tropanes were isolated, characterized, and synthesized by notable chemical researchers. Their significant biological activities have inspired tremendous research efforts toward their synthesis and the elucidation of their pharmacological activity both in academia and in industry. In this chapter, which addresses the developments in this field since 1994, the focus is on the synthesis of these compounds, and several examples of sophisticated synthetic protocols involving both asymmetric and catalytic approaches are described. In addition, the structures of more than 100 new alkaloids are included as well as the applications and pharmacological properties of some tropane alkaloids. 

  • 5.
    Alimohammadzadeh, Rana
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Osong, Sinke H.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Abbaszad Rafi, Abdolrahim
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Cordova, Armando
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Cellulosic Materials: Sustainable Surface Engineering of Lignocellulose and Cellulose by Synergistic Combination of Metal-Free Catalysis and Polyelectrolyte Complexes2019Inngår i: Global Challenges, ISSN 2056-6646, Vol. 3, nr 7, artikkel-id 1970071Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In article number 1900018 by Armando Cordova and co‐workers, the novel combination of metal‐free catalysis and renewable polyelectrolyte complexes leads to synergistic surface engineering of lignocellulose and cellulose fibers derived from wood. This sustainable strategy allows for improvement and introduction of important properties such as strength (up to 100% in Z‐strength), water resistance, and fluorescence to the renewable fibers and cellulosic materials under eco‐friendly conditions.

  • 6.
    Alimohammadzadeh, Rana
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Osong, Sinke H.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Abbaszad Rafi, Abdolrahim
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Cordova, Armando
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Sustainable Surface Engineering of Lignocellulose and Cellulose by Synergistic Combination of Metal‐Free Catalysis and Polyelectrolyte Complexes2019Inngår i: Global Challenges, E-ISSN 2056-6646, Vol. 3, artikkel-id 1900018Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A sustainable strategy for synergistic surface engineering of lignocellulose and cellulose fibers derived from wood by synergistic combination of metal‐free catalysis and renewable polyelectrolyte (PE) complexes is disclosed. The strategy allows for improvement and introduction of important properties such as strength, water resistance, and fluorescence to the renewable fibers and cellulosic materials. For example, the “green” surface engineering significantly increases the strength properties (up to 100% in Z‐strength) of chemi‐thermomechanical pulp (CTMP) and bleached sulphite pulp (BSP)‐derived sheets. Next, performing an organocatalytic silylation with a nontoxic organic acid makes the corresponding lignocellulose and cellulose sheets hydrophobic. A selective color modification of polysaccharides is developed by combining metal‐free catalysis and thiol‐ene click chemistry. Next, fluorescent PE complexes based on cationic starch (CS) and carboxymethylcellulose (CMC) are prepared and used for modification of CTMP or BSP in the presence of a metal‐free catalyst. Laser‐scanning confocal microscopy reveals that the PE‐strength additive is evenly distributed on the CTMP and heterogeneously on the BSP. The fluorescent CS distribution on the CTMP follows the lignin distribution of the lignocellulosic fibers.

  • 7.
    An, Siwen
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Norlin, Börje
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Thungström, Göran
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Comparison of Elemental Analysis Techniques for Fly Ash from Municipal Solid Waste Incineration using X-rays and Electron Beams2019Inngår i: IOP Conference Series: Earth and Environmental Science, Institute of Physics (IOP), 2019, Vol. 337, nr 1, artikkel-id 012007Konferansepaper (Fagfellevurdert)
    Abstract [en]

    With the rapid expansion of the waste incineration business both in Europe and globally, there is a growing need for the elemental analysis for fly ash from municipal solid waste incineration. In this work, samples of washed and unwashed ash from municipal solid waste incineration in Sundsvall are evaluated. Qualitative analysis and semi-quantitative analysis are used to compare two elemental analysis methods, scanning electron microscope with energy dispersive spectroscopy (SEM-EDS) and X-ray fluorescence (XRF) measurement. Both methods are used to retrieve the difference in elemental composition between washed and unwashed fly ash. SEM-EDS accurately detects light elements from well-prepared samples in a vacuum environment, while, for online measurements, XRF is a potential method that analyses hazardous metal content in the fly ash. 

  • 8.
    Andersson, Henrik
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Šuly, Pavol
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion. Tomas Bata University in Zlin, Zlin, Czech Republic.
    Thungström, Göran
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Engholm, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Zhang, Renyun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Mašlík, Jan
    Tomas Bata University in Zlin, Zlin, Czech Republic.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    PEDOT: PSS thermoelectric generators printed on paper substrates2019Inngår i: Journal of Low Power Electronics and Applications, ISSN 2079-9268, Vol. 9, nr 2Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Flexible electronics is a field gathering a growing interest among researchers and companies with widely varying applications, such as organic light emitting diodes, transistors as well as many different sensors. If the circuit should be portable or off-grid, the power sources available are batteries, supercapacitors or some type of power generator. Thermoelectric generators produce electrical energy by the diffusion of charge carriers in response to heat flux caused by a temperature gradient between junctions of dissimilar materials. As wearables, flexible electronics and intelligent packaging applications increase, there is a need for low-cost, recyclable and printable power sources. For such applications, printed thermoelectric generators (TEGs) are an interesting power source, which can also be combined with printable energy storage, such as supercapacitors. Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), or PEDOT:PSS, is a conductive polymer that has gathered interest as a thermoelectric material. Plastic substrates are commonly used for printed electronics, but an interesting and emerging alternative is to use paper. In this article, a printed thermoelectric generator consisting of PEDOT:PSS and silver inks was printed on two common types of paper substrates, which could be used to power electronic circuits on paper. 

  • 9.
    Ashraf, Shakeel
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Forsberg, Viviane
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap. KTH, Wallenberg Wood Science Center, Stockholm.
    Mattsson, Claes G.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Thungström, Göran
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Thermoelectric properties of n-type molybdenum disulfide (MoS2) thin film by using a simple measurement method2019Inngår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, nr 21, artikkel-id 3521Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, a micrometre thin film of molybdenum disulfide (MoS2) is characterized for thermoelectric properties. The sample was prepared through mechanical exfoliation of a molybdenite crystal. The Seebeck coefficient measurement was performed by generating a temperature gradient across the sample and recording the induced electrical voltage, and for this purpose a simple measurement setup was developed. In the measurement, platinum was utilized as reference material in the electrodes. The Seebeck value of MoS2 was estimated to be approximately -600 μV/K at a temperature difference of 40 °C. The negative sign indicates that the polarity of the material is n-type. For measurement of the thermal conductivity, the sample was sandwiched between the heat source and the heat sink, and a steady-state power of 1.42Wwas provided while monitoring the temperature difference across the sample. Based on Fourier's law of conduction, the thermal conductivity of the sample was estimated to be approximately 0.26 Wm-1 K-. The electrical resistivity was estimated to be 29 W cm. The figure of merit of MoS2 was estimated to be 1.99 × 10-4. 

  • 10.
    Bayat, Nazlin
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Carlberg, Torbjörn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Cieslar, M.
    Charles University, Prague, Czech Republic.
    In-Situ Study of Phase Transformations during Homogenization of 6060 and 6063 Al Alloys2019Inngår i: Journal of Physics and Chemistry of Solids, ISSN 0022-3697, E-ISSN 1879-2553, Vol. 130, s. 165-171Artikkel i tidsskrift (Fagfellevurdert)
  • 11.
    Bergvall, Hannah
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Produkt för rullstolsburnas minskande olycksrisk2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 12.
    Blomquist, Nicklas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Large-Scale Graphene Production for Environmentally Friendly and Low-Cost Energy Storage: Production, Coating, and Applications2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    There is great demand for energy-efficient, environmentally sustainable, and cost-effective electrical energy storage devices. One important aspect of this demand is the need for automotive electrification to achieve more energy-efficient transportation at a reasonable cost, thus supporting a fossil-fuel free society. Another important aspect is the requirement for energy storage in the growing field of renewable energy production from wind and solar sources, which generates an irregular supply of electricity due to weather conditions.Much of the research in this area has been conducted in the field of battery technology with impressive results, but the need for rapid storage devices such as supercapacitors is growing. Due to the excellent ability of supercapacitors to handle short peak power pulses with high efficiency along with their long lifetime and superior cyclability, their implementations range from small consumer electronics to electric vehicles and stationary grid applications. Supercapacitors also have the potential to complement batteries to improve pulse efficiency and lifetime of the system, however, the cost of supercapacitors is a significant issue for large-scale commercial use, leading to a demand for sustainable, low-cost materials and simplified manufacturing processes. An important way to address this need is to develop a cost-efficient and environment-friendly large-scale process to produce highly conductive nanographites, such as graphene and graphite nanoplatelets, along with methods to manufacture low-cost electrodes from large area coating.

    In this thesis, I present a novel process to mechanically exfoliate industrial quantities of nanographite from graphite in an aqueous environment with low energy consumption and at controlled shear conditions. The process is based on hydrodynamic tube-shearing and can produce both multilayer graphene and nanometer-thick and micrometer-wide flakes of nanographite. I also describe the production of highly conductive and robust carbon composites based on the addition of nanocellulose during production; these are suitable as electrodes in applications ranging from supercapacitors and batteries to printed electronics and solar cells.Furthermore I demonstrate a scalable route for roll-to-roll coating of the nanographite-nanocellulose electrode material and propose a novel aqueous, low-cost, and metal-free supercapacitor concept with graphite foil functioning as the current collector. The supercapacitors possessedmore than half the specific capacitance of commercial units but achieved a material cost reduction of more than 90 %, demonstrating anenvironment-friendly, low-cost alternative to conventional supercapacitors.

  • 13.
    Blomquist, Nicklas
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Alimadadi, Majid
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Olsen, Martin
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Effects of Geometry on Large-scale Tube-shear Exfoliation of Multilayer Graphene and Nanographite in Water2019Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, nr 1, artikkel-id 8966Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Industrially scalable methods for the production of graphene and other nanographites are needed to achieve cost-efficient commercial products. At present, there are several available routes for the production of these materials but few allow large-scale manufacturing and environmentally friendly low-cost solvents are rarely used. We have previously demonstrated a scalable and low-cost industrial route to produce nanographites by tube-shearing in water suspensions. However, for a deeper understanding of the exfoliation mechanism, how and where the actual exfoliation occurs must be known. This study investigates the effect of shear zone geometry, straight and helical coil tubes, on this system based on both numerical simulation and experimental data. The results show that the helical coil tube achieves a more efficient exfoliation with smaller and thinner flakes than the straight version. Furthermore, only the local wall shear stress in the turbulent flow is sufficient for exfoliation since the laminar flow contribution is well below the needed range, indicating that exfoliation occurs at the tube walls. This explains the exfoliation mechanism of water-based tube-shear exfoliation, which is needed to achieve scaling to industrial levels of few-layer graphene with known and consequent quality.

  • 14.
    Blomquist, Nicklas
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Koppolu, R.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Toivakka, M.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Influence of Substrate in Slot-die Coating of Nanographite/Nanocelluose Electrodes for SupercapacitorsManuskript (preprint) (Annet vitenskapelig)
  • 15.
    Book, Max
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Framtagning av konceptuell planetväxel inom fordonsindustrin2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 16.
    Cordova, Armando
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Afewerki, Samson
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Alimohammadzadeh, Rana
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Sanhueza, Italo
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Tai, Cheuk-Wai
    Stockholm University, Stockholm.
    Osong, Sinke H.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Ibrahem, Ismail
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    A sustainable strategy for production and functionalization of nanocelluloses2019Inngår i: Pure and Applied Chemistry, ISSN 0033-4545, E-ISSN 1365-3075, Vol. 91, nr 5, s. 865-874Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A sustainable strategy for the neat production and surface functionalization of nanocellulose from wood pulp is disclosed. It is based on the combination of organocatalysis and click chemistry ("organoclick" chemistry) and starts with nanocellulose production by organic acid catalyzed hydrolysis and esterification of the pulp under neat conditions followed by homogenization. This nanocellulose fabrication route is scalable, reduces energy consumption and the organic acid can be efficiently recycled. Next, the surface is catalytically engineered by "organoclick" chemistry, which allows for selective and versatile attachment of different organic molecules (e.g. fluorescent probes, catalyst and pharmaceuticals). It also enables binding of metal ions and nanoparticles. This was exemplified by the fabrication of a heterogeneous nanocellulose-palladium nanoparticle catalyst, which is used for Suzuki cross-coupling transformations in water. The disclosed surface functionalization methodology is broad in scope and applicable to different nanocelluloses and cellulose based materials as well.

  • 17.
    Ebadi, Seyed Morteza
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Örtegren, Jonas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Bayati, Mohammad Sajjad
    Ram, Siamak Bonyadi
    A Multipurpose and Highly-Compact Plasmonic Filter based on Metal-Insulator-Metal Waveguides2020Inngår i: IEEE Photonics Journal, ISSN 1097-5764, E-ISSN 1943-0655Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A multipurpose and ultra-compact nanoplasmonic wavelength filter based on stub structure in a metal-insulator-metal (MIM) waveguide is suggested and numerically investigated. A novel approach of connecting two stepped-like apertures to both input and output ports is applied to form Fabry-Perot (FP) cavities, which enabled the structure to act as a dual band-pass filter at wavelengths 1310 nm and 1550 nm. It is shown that the variation in cavities’ length allows to realize a long-wavelength cutoff filter, and cutoff wavelength can be easily tuned by adjusting the length of the cavities. Furthermore, it is revealed that increasing the gap between the stepped-like apertures and the cavities provides a triple band-pass at telecom wavelengths, e.g. 1267.5nm, 1414.19 nm, and 1644.7 nm. The tunable broadband high-pass wavelength filter is then achieved while the lengths of stepped-like apertures and stub resonators are set to be identical. Finally, a tunable nearly perfect absorber can be obtained by varying the width of stub resonators. Therefore, because of functionality, size, as well as efficiency the proposed plasmonic filter may greatly contribute to miniaturization of next generation of photonic integrated circuits (PICs), and find applications in on-chip integration and wavelength-division multiplexing (WDM) in optical communication systems.

  • 18.
    Ekenberg, Greta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Utveckling av verktyg för rullbyte hos bandtransportör2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 19.
    Ekström, Magnus
    et al.
    Umeå University, Umeå; SLU, Umeå.
    Sandring, Saskia
    SLU, Umeå.
    Grafström, Anton
    SLU, Umeå.
    Esseen, Per-Anders
    Umeå University, Umeå.
    Jonsson, Bengt-Gunnar
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Ståhl, Göran
    SLU, Umeå.
    Estimating density from presence/absence data in clustered populations2020Inngår i: Methods in Ecology and Evolution, ISSN 2041-210X, E-ISSN 2041-210XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Inventories of plant populations are fundamental in ecological research and monitoring, but such surveys are often prone to field assessment errors. Presence/absence (P/A) sampling may have advantages over plant cover assessments for reducing such errors. However, the linking between P/A data and plant density depends on model assumptions for plant spatial distributions. Previous studies have shown, for example, how that plant density can be estimated under Poisson model assumptions on the plant locations. In this study, new methods are developed and evaluated for linking P/A data with plant density assuming that plants occur in clustered spatial patterns. New theory was derived for estimating plant density under Neyman–Scott-type cluster models such as the Matérn and Thomas cluster processes. Suggested estimators, corresponding confidence intervals and a proposed goodness-of-fit test were evaluated in a Monte Carlo simulation study assuming a Matérn cluster process. Furthermore, the estimators were applied to plant data from environmental monitoring in Sweden to demonstrate their empirical application. The simulation study showed that our methods work well for large enough sample sizes. The judgment of what is' large enough’ is often difficult, but simulations indicate that a sample size is large enough when the sampling distributions of the parameter estimators are symmetric or mildly skewed. Bootstrap may be used to check whether this is true. The empirical results suggest that the derived methodology may be useful for estimating density of plants such as Leucanthemum vulgare and Scorzonera humilis. By developing estimators of plant density from P/A data under realistic model assumptions about plants' spatial distributions, P/A sampling will become a more useful tool for inventories of plant populations. Our new theory is an important step in this direction. 

  • 20.
    Fahmida Zaman, Irin
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Wood decaying fungi gain competitive strength through competition2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 21.
    Forsberg, Viviane
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Liquid-Phase Exfoliation of Two-Dimensional Materials: Applications, deposition methods and printed electronics on paper2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    After the unprecedented success of graphene research, other materials that can also be exfoliated into thin layers, like Transition metal dichalcogenides (TMDs) such as molybdenum disulfide (MoS2), have also become the subjects of extensive studies. As one of the most promising methods for large scale production of such materials, liquid-phase exfoliation (LPE) has also been the subject of extensive research and is maturing as a field to the point that devices using additive manufacturing and printed nanosheets are often reported. The stability of the nanosheets in environmentally friendly solvents, particularly in water, with or without stabilizers, is still a focus of great interest for sustainable and commercial production. In this thesis, different methods of LPE in water with and without stabilizers are investigated and discussed. Stabilizers such as surfactant sodium dodecyl sulfate (SDS) and modified cellulose2-hydroxyethyl cellulose (HEC), were employed. Because waterdoes not have surface energy parameters that match those of2D materials, the dispersions in water do not usually have a high yield. Therefore, to circumvent the use of organic solvents that are known to be able to successfully exfoliate and stabilize nanosheets of two-dimensional materials, this thesis focuses on water as the solution-process medium for exfoliation and the assisting stabilizers used to keep the exfoliated nanomaterials in dispersion with a long half-time. Surfactant-assisted dispersions are discussed together with test-printing resultsusing inkjet to deposit the material. Process parameters for the LPE method using HEC as a stabilizer are presented together with thin nanosheets characterized by Raman spectroscopy. Dispersions using HEC presented the longest half-time among the studied methods, higher than previously reported values for methods using mixed low-boiling-point solvents. Devices using exfoliated nanosheets have been fabricated and presented in the present study. The photoconductivity of MoS2 using a device fabricated with LPE MoS2 nanosheets and the cathodoluminescence of LPE MoS2 are discussed. Although fabricated with mechanically exfoliated nanosheets and not LPE ones, another photodetector fabricated with one of the MoS2 grades used in this thesis is presented to highlight the excellent photoresponse of this material. A method of producing thin nanosheets with-out stabilizers by pre-processing the MoS2 grades withs and papers is introduced. With this method, nanosheets with a lateral size of around 200nm and a concentration around 0.14 g L−1 - that is half the concentration at the same processing conditions in solvent n-methyl pyrrolidone (NMP) - are discussed. Inkjet printing as a deposition method is discussed together with the requirements for the 2D inks. Printed organic electronics using the conductive polymer PEDOT:PSS are compared to those using commercially-available graphene ink, with a focus on printing on paper substrates. In order to bring the thesis into perspective from materials to device fabrication, I study the suitability of inkjet paper substrates for printed electronics, by extensively characterizing the chemical and physical properties of their ink-receiving layers (IRLs) and their impact on the electronic properties of the conductive printed lines.

  • 22.
    Forsberg, Viviane
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Process parameters of liquid-phase exfoliation of MoS2 in waterstabilized with 2-hydroxyethyl celluloseManuskript (preprint) (Annet vitenskapelig)
  • 23.
    Forsberg, Viviane
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap. KTH, Stockholm; Wallenberg Wood Science Centre, Stockholm.
    Mašlík, Jan
    Tomas Bata University in Zlín, Zlín, Czech Republic.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Electronic performance of printed PEDOT:PSS lines correlated to the physical and chemical properties of coated inkjet papers2019Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, nr 41, s. 23925-23938Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PEDOT:PSS organic printed electronics chemical interactions with the ink-receiving layer (IRL) of monopolar inkjet paper substrates and coating color composition were evaluated through Raman spectroscopy mapping in Z (depth) and (XY) direction, Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray spectroscopy (EDS). Other evaluated properties of the IRLs were pore size distribution (PSD), surface roughness, ink de-wetting, surface energy and the impact of such characteristics on the electronics performance of the printed layers. Resin-coated inkjet papers were compared to a multilayer coated paper substrate that also contained an IRL but did not contain the plastic polyethylene (PE) resin layer. This substrate showed better electronic performance (i.e., lower sheet resistance), which we attributed to the inert coating composition, higher surface roughness and higher polarity of the surface which influenced the de-wetting of the ink. The novelty is that this substrate was rougher and with somewhat lower printing quality but with better electronic performance and the advantage of not having PE in their composite structure, which favors recycling. © 2019 The Royal Society of Chemistry.

  • 24.
    Grafström, Anton
    et al.
    Swedish Univ Agr Sci, Umeå.
    Ekström, Magnus
    Swedish Univ Agr Sci, Umeå; Umeå Univ, Umeå.
    Jonsson, Bengt-Gunnar
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Esseen, Per-Anders
    Umeå Univ, Umeå.
    Stahl, Göran
    Swedish Univ Agr Sci, Umeå.
    On combining independent probability samples2019Inngår i: Survey Methodology, ISSN 0714-0045, E-ISSN 1492-0921, Vol. 45, nr 2, s. 349-364Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Merging available sources of information is becoming increasingly important for improving estimates of population characteristics in a variety of fields. In presence of several independent probability samples from a finite population we investigate options for a combined estimator of the population total, based on either a linear combination of the separate estimators or on the combined sample approach. A linear combination estimator based on estimated variances can be biased as the separate estimators of the population total can be highly correlated to their respective variance estimators. We illustrate the possibility to use the combined sample to estimate the variances of the separate estimators, which results in general pooled variance estimators. These pooled variance estimators use all available information and have potential to significantly reduce bias of a linear combination of separate estimators.

  • 25.
    Grafström, Anton
    et al.
    SLU, Umeå.
    Ekström, Magnus
    Umeå universitet, Umeå; SLU, Umeå.
    Jonsson, Bengt-Gunnar
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Esseen, Per-Anders
    Umeå universitet, Umeå.
    Ståhl, Göran
    SLU, Umeå.
    On combining independent probability samples2019Inngår i: Survey Methodology, ISSN 0714-0045, E-ISSN 1492-0921, Vol. 45, nr 2, s. 371-387Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Merging available sources of information is becoming increasingly important for improving estimates ofpopulation characteristics in a variety of fields. In presence of several independent probability samples from afinite population we investigate options for a combined estimator of the population total, based on either a linearcombination of the separate estimators or on the combined sample approach. A linear combination estimatorbased on estimated variances can be biased as the separate estimators of the population total can be highlycorrelated to their respective variance estimators. We illustrate the possibility to use the combined sample toestimate the variances of the separate estimators, which results in general pooled variance estimators. Thesepooled variance estimators use all available information and have potential to significantly reduce bias of a linearcombination of separate estimators.

  • 26.
    Hailegebreal, Ermias
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Utveckling av mobil dockning för en tvåarmad robot2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    MTEK Industry är ett företag som utvecklar färdiga produktionslinjer till företag runt om i världen. En del av produktionslösningen bygger på användandet av roboten YuMi som är utvecklad av ABB. Då MTEK vill erbjuda en så flexibel lösning som möjligt har de utvecklat en fastsättningsmetod som fäster roboten mot arbetsbänken med hjälp av elektromagnetiska plattor; en mobil dockningsmetod. Den befintliga lösningen har dock ett spel i axiell led på grund av konstruktionen vilket påverkar precisionen för roboten negativt. Målet för projektarbetet har därmed varit att utveckla en ny fastsättningsmetod med förbättrad tolerans. Förundersökningen har utförts med hjälp av litteraturstudier, analys av befintlig fastsättningsmetod, löpande intervjuer med handledare och VD på MTEK samt en studie av liknande fastsättningsmetoder. Den bidrog med kunskap inför den konceptgenererande fasen som utfördes med hjälp av brainstorming och sållning. En konstruktion och simulation av konceptet utfördes i SolidWorks där en slutgiltig produkt sedan kunde produceras och analyseras. Förundersökningen visade att det idag enbart finns en liknande lösning för mobil dockning av robotar, Opiflex Automations lösning ”System for docking of a movable platform”. Dockningsmetoden som använder sig av styrpinnar är patenterad vilket resulterade i att många idéer till ett koncept för MTEK inte gick att använda då de inte uppfyllde kraven som hade ställts. Istället för ett helt nytt koncept utvecklades deras befintliga dockningsmetod som resulterade i ett slutkoncept med en förbättrad tolerans på nästan 10 gånger. Konceptet uppfyllde samtliga krav som var ställda från MTEK och anses därmed som lyckat. 

  • 27.
    Hellström, Douglas
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Sundström, Simon
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Standardisering av OQL-200 systemet: Konstruktion av automatiskt snabbfästessystem för hjullastare2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Målet med denna undersökning har varit att konstruera ett standardiserat snabbfäste som passar rörelsemönstret hos minst fyra hjullastare med en tjänstevikt upp till åtta ton. Snabbfästet ska konstrueras med ett helt standardiserat redskapsfäste. Snabbfästet ska ges möjlighet till små dimensions-förändringar som ska underlätta för konstruktörsarbetet på OilQuick. En tidsplan och en kravspecifikation sattes upp, följt av en marknadsundersökning på hjullastare och snabbfästen. Fem hjullastare mättes och modellera-des digitalt. Genom geometrierna hos hjullastarna beräknades relevant maskindata såsom den maximala momentkraften kring nedre infästningen på snabbfästet. Detta presenterades i en tabell. Konceptutvecklingen inleddes med att presentera begränsningar i modelleringen genom att bestämma in-fästningspunkter på maskiner och de standardiserade måtten på redskaps-fästet. Under konceptutvecklingen togs fyra koncept fram där samtliga koncept skulle tillåta maskinernas rörelsemönster. Koncepten utvärderades ge-nom Concept Scoring som utgick ifrån kravspecifikationen. Resultatet visade på ett teoretiskt fungerande snabbfästeskoncept som uppfyller målet och stora delar av den uppsatta kravspecifikationen. Slutkonceptet tillåter enkel anpassningsbarhet mellan maskiner och hindrar inte deras rörelsemönster. Nedre delen av snabbfästet är standardiserad och redskapsfästet är fullständigt standardiserat. Interface mellan snabbfästet och redskapsfästet är standardiserat. Hydrauliklösningen på snabbfästet är innesluten och låsningen sker på undersidan av snabbfästet vilket bidrar till hög felsäkerhet vid låsning, låg klämrisk och liten dammbildning vid hydraulik och elektricitets-inkopplingen. Redskapsfästet är utrustad med en skyddslucka som automatiskt öppnas vid inkoppling. Undersökningen har visat att det är möjligt att skapa en snabbfästesstandard för hjullastare i den angivna viktklassen men det kommer med en del krav. Slutkonceptet kräver att ett fåtal länkar hos de uppmätta maskinerna byts ut.

  • 28.
    Höglund, Sebastian
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Staaf, Carl
    Mittuniversitetet.
    Utveckling av metod för finkalibriga ballistiska tester2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 29.
    Jawa, Mohammed
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Konstruktionsförslag för lastanordning till likbil2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Syftet med arbetet var att analysera marknaden för att sedan ta fram ett konstruktionsunderlag för en lastanordning i en likbil för företaget Ortman Specialanpassningar. Konceptet skall innefatta en konstruktion med bland annat funktionalitetskrav som skall underlätta förflyttning och förvaring av en kista i en likbil. Projektet inleddes med en idé tillsammans med en förstudie som sedan gick över till en designprocess som är en utvecklingsprocess som ger användaren flera olika metoder under flera faser. Projektet gick igenom flera olika stadie där projektet planerades, kontexten utforskades, koncept utformning och till slut gick över till ett konstruktionsunderlags-stadie. Därefter analyserades konstruktionsunderlaget och simulerades genom en belastningsanalys med hjälp av SolidWorks. Material valdes, där dessa val baserades på projektets kravspecifikation. Slutligen renderades konstruktionsunderlaget i programmet KeyShot.

  • 30.
    Jawad, Mohammed
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Konstruktionsförslag för lastanordning till likbil2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 31.
    Jiang, Yan
    et al.
    Stockholm University, Stockholm.
    Deiana, Luca
    Stockholm University, Stockholm.
    Zhang, Keihang
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Lin, Shuangzheng
    Stockholm University, Stockholm.
    Córdova, Armando
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Total Asymmetric Synthesis of Quinine, Quinidine, and Analogues via Catalytic Enantioselective Cascade Transformations2019Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 35, s. 6016-6023Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A catalytic asymmetric strategy for the total synthesis of quinuclidine natural products, which includes the completed enantioselective synthesis of the classical targets quinine and quinidine is disclosed. It is based on catalytic asymmetric cascade transformations, which paves the road for the synthesis of both enantiomers of the crucial C4 stereocenter with high enantioselectivity (up to 99 % ee) in one pot. Next, developing a route to all possible stereoisomers of a common early-stage intermediate sets the stage for the total synthesis of different enantiomers or epimers of quinine, quinidine and analogues with high selectivity. 

  • 32.
    Jiang, Yuting
    et al.
    Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing; University of Chinese Academy of Sciences, Beijing.
    Wang, Yang
    Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing .
    Wu, Heting
    Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing;University of Chinese Academy of Sciences, Beijing .
    Wang, Yuanhao
    Chinese Academy of Sciences, Urumqi, Xinjiang.
    Zhang, Renyun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Yang, Ya
    Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing;University of Chinese Academy of Sciences, Beijing; Guangxi University, Nanning.
    Laser-Etched Stretchable Graphene–Polymer Composite Array for Sensitive Strain and Viscosity Sensors2019Inngår i: Nano-Micro Letters, ISSN 2150-5551, Vol. 11, nr 1, artikkel-id 99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ability to control surface wettability and liquid spreading on textured surfaces is of interest for extensive applications. Soft materials have prominent advantages for producing the smart coatings with multiple functions for strain sensing. Here, we report a simple method to prepare flexible hydrophobic smart coatings using graphene–polymer films. Arrays of individual patterns in the films were created by laser engraving and controlled the contact angle of small drops by pinning the contact lines in a horizontal tensile range of 0–200%. By means of experiments and model, we demonstrate that the ductility of drops is relied on the height-to-spacing ratio of the individual pattern and the intrinsic contact angle. Moreover, the change of drop size was utilized to measure the applied strain and liquid viscosity, enabling a strain sensitivity as high as 1068 μm2/%. The proposed laser-etched stretchable graphene–polymer composite has potential applications in DNA microarrays, biological assays, soft robots, and so on.

  • 33.
    Johansson, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Produktutveckling av tillbehör för bandsågverk: Utveckling av tillbehör för minskad förslitning av sågblad2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Rapporten presenterar ett utvecklingsprojekt utfört för Logosol AB i Härnösand. Projektet innefattar produktutveckling av ett tillbehör för bandsågverk B1001, där syftet var att förlänga livslängden på bandsågverkets såg-blad. Betydande del av förslitningen på sågbladen förekommer genom att föroreningar i stockarnas bark dras med genom stocken av sågbladet, detta medför sedan ökad förslitning och kortare livslängd på bandsågverkets såg-blad. Utveckling av ett tillbehör för att motverka detta grundades i att skapa en konstruktion som tar bort

  • 34.
    Johansson, Filip
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Säkerhet- och kvalitetsanalys av rulltrappor: En undersökning av trappsteg med avseende på hållfasthet2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 35.
    Jonsson, Bengt-Gunnar
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Svensson, Johan
    SLU, Umeå.
    Mikusiński, Grzegorz
    SLU, Riddarhyttan/Skinnskatteberg.
    Manton, Michael
    Vytautas Magnus University, Akademija, Kaunas District, Lithuania.
    Angelstam, Per
    SLU, Skinnskatteberg.
    European Union's last intact forest landscapes are at a value chain crossroad between multiple use and intensified wood production2019Inngår i: Forests, ISSN 1999-4907, E-ISSN 1999-4907, Vol. 10, nr 7, artikkel-id 564Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Research Highlights: The European Union's last large intact forest landscapes along the Scandinavian Mountain range in Sweden offer unique opportunities for conservation of biodiversity, ecological integrity and resilience. However, these forests are at a crossroad between intensified wood production aimed at bio-economy, and rural development based on multi-functional forest landscapes for future-oriented forest value chains. Background and Objectives:We (1) estimate the area of near-natural forests potentially remaining for forest harvesting and wood production, or as green infrastructure for biodiversity conservation and human well-being in rural areas, (2) review how forest and conservation policies have so far succeeded to reduce the loss of mountain forests, and (3) discuss what economic, socio-cultural and ecological values that are at stake, as well as different governance and management solutions.Materials andMethods: First, we estimated the remaining amount of intact mountain forests using (1) the Swedish National Forest Inventory, (2) protected area statistics, (3) forest harvest permit applications and actually harvested forests, (4) remote sensing wall-to-wall data on forests not subject to clear-felling since the mid-1950s, (5) mapping of productive and non-productive forestland, and (6) estimates of mean annual final felling rate. Second, we review policy documents related to the emergence of land use regulation in north Sweden, including the mountain forest border, and illustrate this with an actual case that has had significant policy implementation importance. Results: There is a clear difference between the proportions of formally protected productive forestland above the mountain forest border (52.5%) and north Sweden in general (6.3%). A total of 300,000 ha of previously not clear-felled mountain forest outside protected areas remain, which can support novel value chains that are not achievable elsewhere. Conclusions: The mountain forests in Sweden provide unique conservation values in the European Union. Since the beginning of the 1990s, policy regulations have been successful in limiting forest harvesting. Currently, however, mountain forests are a battle ground regarding intensification of forest use, including logging of forests that have never been subject to clear-felling systems vs. nature conservation and wilderness as a base for rural development. The ability of mountain municipalities to encourage sustainable rural forest landscapes must be strengthened. 

  • 36.
    Koli, Rohit R.
    et al.
    Shivaji Univ, Kolhapur, Maharashtra, India; Shivaji Univ, Kolhapur, Maharashtra, India.
    Phadatare, Manisha R.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap. DY Patil Univ, Kolhapur, Maharashtra, India.
    Sinha, Bhavesh B.
    Univ Mumbai, Mumbai, Maharashtra, India.
    Sakate, Deepak M.
    Shivaji Univ, Kolhapur, Maharashtra, India.
    Ghule, Anil V.
    Shivaji Univ, Kolhapur, Maharashtra, India.
    Ghodake, Gajanan S.
    Dongguk Univ Seoul, Goyang Si, Gyeonggi Do, India.
    Deshpande, Nishad G.
    Shivaji Univ, Dept Phys, Kolhapur, Maharashtra, India.
    Fulari, Vijay J.
    Shivaji Univ, Kolhapur, Maharashtra, India.
    Gram bean extract-mediated synthesis of Fe3O4 nanoparticles for tuning the magneto-structural properties that influence the hyperthermia performance2019Inngår i: Journal of the Taiwan Institute of Chemical Engineers / Elsevier, ISSN 1876-1070, E-ISSN 1876-1089, Vol. 95, s. 357-368Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A green synthesis of biocompatible magnetite (Fe3O4) nanoparticles (MNPs) using a combination of urea (U) and gram-bean extract (GBE, Cicer arietinum L.) is reported. The particle size of similar to 13 nm and highly stable magnetite phase is observed for GBE-U mediated MNPs. On the other hand, the MNPs synthesized using either U or GBE shows larger particle size and uneven size distribution. Interestingly, the sample with particle size similar to 13 nm shows optimum heat generation capacity (measured in specific absorption rate, i.e., SAR) near to the therapeutic temperature (43 degrees C) with least-variance. To investigate the influence of various factors such as variation in MNPs weight concentration (W-t), applied alternating magnetic field (AMF), saturation magnetization (M-s), magnetization rate (R-m), etc. on SAR, a multiple linear regression model (MLRM) is used. The study reveals a positive correlation of SAR with R-m, and AMF values while the negative correlation with M-s and W-t. Ultimately, the present green synthesis is the affordable approach for preparing stable and tiny MNPs. Moreover, MLRM is found to be a useful theoretical tool for understanding the influence of MNPs on hyperthermia performance. 

  • 37.
    Larsson, Rebecka
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Optimering av interna leveranser i maskinlinjen – anodhängare och maskiner2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 38.
    Ljunggren, Joel
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Jonsson, Bengt-Gunnar
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Edman, Mattias
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Hedenström, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Antifungal efficiency of individual compounds and evaluation of non-linear effects by recombining fractionated turpentine2020Inngår i: Microchemical journal (Print), ISSN 0026-265X, E-ISSN 1095-9149, Vol. 153, artikkel-id 104325Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A combination between a reductive and a holistic assay was employed to investigate whole fraction, synergistic, antagonistic and individual compound efficacy of vacuumdistilled turpentine fractions against the economically important brown-rot fungus Coniophora puteana. The fungus was subjected to recombinations of turpentine fractions at a concentration of 1000 ppm. All combinations exhibited useful antifungal properties, but some antifungal mixtures showed a more pronounced effect than the expected level of inhibition. Synergistic effects by a two-fold factor and minor antagonistic effects were observed. Complete growth inhibition of C. puteana was observed by a fraction obtained after distilling 1 L turpentine at 111–177°C (0.5 mbar) as well as by mixing it with another fraction withdrawn at 70–79°C (0.5 mbar). Chemical compositions of distilled fractions were determined through GC–MS analysis and Orthogonal Partial Least Squares (OPLS) multivariate data analysis of GC–MS chromatograms was employed to zoom in on the most active compounds responsible for antifungal activity. Isomers of epicubenol, the hydrocarbon aromatic compound ar-himachalene and α-cadinol are suggested as effective antifungal compounds. In addition, a subsequent fractionation of the most effective fraction was performed with preparatory gas chromatography and subfractions showed similar or better efficacy than previously observed. Our work demonstrates the possibility to retain adequate synergistic antifungal efficiency and offers an opportunity to explore the effects of individual compounds originating from the same crude sample.

  • 39.
    Molina-Lopez, F.
    et al.
    Stanford University, Stanford, CA United States; KU Leuven, Leuven, Belgium.
    Gao, T. Z.
    Stanford University, Stanford, CA United States.
    Kraft, U.
    Stanford University, Stanford, CA United States; University of Cambridge, Cambridge, United Kingdom.
    Zhu, C.
    Stanford University, Stanford, CA United States.
    Öhlund, Thomas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap. Stanford University, Stanford, CA United States.
    Pfattner, R.
    Stanford University, Stanford, CA United States; Institute of Materials Science of Barcelona (ICMAB-CISC), Bellaterra, Spain.
    Feig, V. R.
    Stanford University, Stanford, CA United States.
    Kim, Y.
    Stanford University, Stanford, CA United States.
    Wang, S.
    Stanford University, Stanford, CA United States; University of Chicago, Chicago, IL United States.
    Yun, Y.
    Samsung Advanced Institute of Technology, Suwon, South Korea.
    Bao, Z.
    Stanford University, Stanford, CA United States.
    Inkjet-printed stretchable and low voltage synaptic transistor array2019Inngår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, nr 1, artikkel-id 2676Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wearable and skin electronics benefit from mechanically soft and stretchable materials to conform to curved and dynamic surfaces, thereby enabling seamless integration with the human body. However, such materials are challenging to process using traditional microelectronics techniques. Here, stretchable transistor arrays are patterned exclusively from solution by inkjet printing of polymers and carbon nanotubes. The additive, non-contact and maskless nature of inkjet printing provides a simple, inexpensive and scalable route for stacking and patterning these chemically-sensitive materials over large areas. The transistors, which are stable at ambient conditions, display mobilities as high as 30 cm2 V−1 s−1 and currents per channel width of 0.2 mA cm−1 at operation voltages as low as 1 V, owing to the ionic character of their printed gate dielectric. Furthermore, these transistors with double-layer capacitive dielectric can mimic the synaptic behavior of neurons, making them interesting for conformal brain-machine interfaces and other wearable bioelectronics. 

  • 40.
    Morian, Viktor
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Fästanordningskoncept för skridskoslipmaskin2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 41.
    Nilsson, Oscar
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Ergonomisk utformning av punktsvets2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 42.
    Niskane, Tomas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Testrigg: Utveckling av laborationsutrustning2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 43. Niskanen, I.
    et al.
    Forsberg, Viviane
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Zakrisson, Daniel
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Engberg, Birgitta A.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Heikkilä, R.
    Thungström, Göran
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Determination of relative solids concentration in homogeneous dual component pulp-filler suspension by multi-spectrophotometer2020Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The concentration of fibers and fillers in the pulp suspension is an important parameter in the monitoring process. This paper proposes a versatile optical measurement system to estimate the concentration of a solids mixture in water. The geometry used in a multi-spectrophotometer (MSM) enables the controlled observation of transmission, and forward scattering light from the suspension in the UV-visible spectral range. We have developed the new fibers mixing system which gives a homogenous distribution of the fines and fillers making it possible to increase the reproducibility and accuracy of the measurement. The data analysis is based on the Beer-Lambert law and CIELAB color space equations. The results show that the proposed method is accurate for measuring the fines and filler concentrations in multicomponent suspensions. 

  • 44.
    Niskanen, Ilpo
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion. University of Oulu, Oulu, Finland.
    Forsberg, Viviane
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap. KTH.
    Zakrisson, Daniel
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Reza, Salim
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Andres, Britta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Fedorov, Igor
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Suopajärvi, Terhi
    University of Oulu, Oulu, Finland.
    Liimatainen, Henrikki
    University of Oulu, Oulu, Finland.
    Thungström, Göran
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Determination of nanoparticle size using Rayleigh approximation and Mie theory2019Inngår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 201, nr 29, s. 222-229Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Accurate determination of the size of nanoparticles has an important role in many different scientific and industrial purposes, such as in material, medical and environment sciences, colloidal chemistry and astrophysics. We describe an effective optical method to determine the size of nanoparticles by analysis of transmission and scattering of visible spectral range data from a designed UV-Vis multi-spectrophotometer. The size of the nanoparticles was calculated from the extinction cross section of the particles using Rayleigh approximation and Mie theory. We validated the method using polystyrene nanospheres, cellulose nanofibrils, and cellulose nanocrystals. A good agreement was achieved through graphical analysis between measured extinction cross section values and theoretical Rayleigh approximation and Mie theory predictions for the sizes of polystyrene nanospheres at wavelength range 450 - 750 nm. Provided that Rayleigh approximation's forward scattering (FS)/back scattering (BS) ratio was smaller than 1.3 and Mie theory's FS/BS ratio was smaller than 1.8. A good fit for the hydrodynamic diameter of nanocellulose was achieved using the Mie theory and Rayleigh approximation. However, due to the high aspect ratio of nanocellulose, the obtained results do not directly reflect the actual cross-sectional diameters of the nanocellulose. Overall, the method is a fast, relatively easy, and simple technique to determine the size of a particle by a spectrophotometer. Consequently, the method can be utilized for example in production and quality control purposes as well as for research and development applications.

  • 45.
    Nordvall, Robbin
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Optimering av mekaniska egenskaper för bärverk2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 46.
    Nyström, Alexander
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Free-form compensation of cemented carbide inserts: A new method for systematic compensation2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The manufacturing of cemented carbide tools is a continuous process that keeps developing along with new technologies and possibilities. To increase efficiency when developing these tools, every step in the process needs to be optimized and kept up to date in order to remain relevant in a competitive market.

    This report presents a new method for free-form compensation with the use of newly developed simulations. The simulation creates a deformed model that accurately identifies most of the deformations that occur during the press and sinter of an insert. With this data, it becomes possible to perform compensations before any tool is produced. This will allow a higher efficiency when developing new tools and in turn, reduce the material waste.

    The developed method is based on point cloud transformation which can be reconstructed to allow an automated compensation process. By using the simulated data and nominal model, the difference between every surface point can be calculated and compensated accordingly using MATLAB.

    In this project, a completely new insert has been designed with extreme geometrical shapes to evaluate the method. To verify this, two prototypes have been created. One reference insert with the usual 18% compensation and an insert based on the new compensation method. By comparing the two, it is visible that the method effectively reduces the tolerances on the first compensation loop. There is, however, much work left to implement this method in today's manufacturing. In order to use the method, several steps need to be tested further. The goal of this method is to completely remove the need for several compensation loops and prevent manual compensation practice.

     

  • 47.
    Olsen, Martin
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Nanomechanics – Quantum Size Effects, Contacts, and Triboelectricity2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Nanomechanics is different from the mechanics that we experience in everyday life. At the nano-scale, typically defined as 1 to 100 nanometers, some phenomena are of crucial importance, while the same phenomena can be completely neglected on a larger scale. For example, the feet of a gekko are covered by nanocontacts that yield such high adhesion forces that the animal can run up on walls and even on the ceiling. At small enough distances, matter and energy become discrete, and the description of the phenomena occurring at this scale requires quantum mechanics. However, at room temperature the transitions between quantized energy levels may be concealed by the thermal vibrations of the system. As two surfaces approach each other and come into contact, electrostatic forces and van der Waals forces may cause redistribution of matter at the nano level. One effect that may occur upon contact between two surfaces is the triboelectric effect, in which charge is transferred from one surface to the other.This effect can be used to generate electricity in triboelectric nanogenerators (TENGs), where two surfaces are repeatedly brought in and out of contact, and where the charge transfer is turned into electrical energy.

    This thesis concerns nanomechanics addressing whether quantum mechanics play a role in elastic deformation, as well as various mechanical aspects of nanocontacts including electric charging. The objectives are to contribute to the understanding when quantum effects are of importance at the nanolevel, increase the fundamental understanding of the mechanisms responsible for triboelectric phenomena and apply the triboelectric effect to a wind harvesting device.

    For more insight into whether quantum effects are of importance in nanomechanics, we use a one dimensional jellium model and the standard beam theory allowing the spring constant of an oscillating nanowire cantilever to be calculated. As the nanowire bends, more electron states fit in its cross section, giving rise to an amplitude dependent resonance frequency of the nanowire oscillations.

    Furthermore, a model for electric field induced surface diffusion of adatoms was developed. The model takes electrostatic forces and van der Waals forces into account as a voltage is applied between a scanning tunneling microscope tip and a sample. The calculated force on the adatoms at the surface of the sample, which is stemming from the inhomogeneous electric field and the dipole moment of the adatoms, is relatively small, but due to thermal vibrations adatoms diffuse and form mounds at the sample.

    When bringing two different materials into contact, the difference in triboelectric potentials between the materials results in electric charging. To increase the understanding of triboelectricity, a two-level Schottky model, assuming ion transfer, was developed to describe the temperature dependence of the triboelectric effect for a TENG. The two levels correspond to the binding energy for ions on the two surfaces that are brought into contact, where the difference in binding energy enters the Boltzmanndistribution. The model describes the decreasing triboelectric effect in TENG:s with increasing temperature as described in the literature, and results in a separation energy, which is of the right order of magnitude for physically adsorbed atoms.

    It was recently demonstrated that TENGs can convert wind energy into electrical energy. Here, a TENG based on a plastic film fluttering between two copper electrodes was constructed. It was found that the frequency of the the fluttering film increases linearly with the wind speed. TENG:s designed in this way generate electricity already at low wind speed, and we therefore expect such TENG:s to be useful both as generators and speed sensors in the future.

    While quantum mechanics is of importance in a limited number of nanomechanical systems, nanocontacts have a broader meaning, and are crucial for the understanding of triboelectric phenomena. We anticipate that the findings in this thesis will contribute to a better understanding of nanomechanics, in particular the mechanism of triboelectricity.

  • 48.
    Olsen, Martin
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Zhang, Renyun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Örtegren, Jonas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Andersson, Henrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för elektronikkonstruktion.
    Yang, Ya
    CAS Center for excellence in Nanoscience, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Science.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Frequency and voltage response of a wind-driven fluttering triboelectric nanogenerator2019Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, nr 1, artikkel-id 5543Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Triboelectric nanogenerators (TENG:s) are used as efficient energy transducers in energy harvesting converting mechanical energy into electrical energy. Wind is an abundant source of mechanical energy but how should a good triboelectric wind harvester be designed? We have built and studied a TENG driven by air flow in a table-top sized wind tunnel. Our TENG constitutes of a plastic film of size10 cm × 2 cm which is fluttering between two copper electrodes generating enough power to light up a battery of LED:s. We measured the voltage and frequency of fluttering at different wind speeds from zero up to 8 m/s for three electrode distances 6 mm, 10 mm and 14 mm. We found that the frequency increases linearly with the wind speed with a cutoff at some low speed. Power was generated already at 1.6 m/s. We seem to be able to explain the observed frequency dependence on wind speed by assuming excitation of the film into different harmonics in response to von Kármán vortices. We also find that the voltage increase linearly with frequency. We anticipate that TENG:s of this design could be useful both as generators and speed sensors because they work at low air speeds.

  • 49.
    Phadatare, Manisha R.
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap. Deemed Univ, Maharashtra, India.
    Patil, Rohan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Blomquist, Nicklas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Örtegren, Jonas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Meshram, Jagruti
    Deemed Univ, Maharashtra, India.
    Hernández, Guiomar
    Uppsala Univ, Uppsala.
    Brandell, Daniel
    Uppsala Univ, Uppsala.
    Leifer, Klaus
    Uppsala Univ, Uppsala.
    Sathyanath, Sharath Kumar Manjeshwar
    Uppsala Univ, Uppsala.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Silicon-Nanographite Aerogel-Based Anodes for High Performance Lithium Ion Batteries2019Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, artikkel-id 14621Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To increase the energy storage density of lithium-ion batteries, silicon anodes have been explored due to their high capacity. One of the main challenges for silicon anodes are large volume variations during the lithiation processes. Recently, several high-performance schemes have been demonstrated with increased life cycles utilizing nanomaterials such as nanoparticles, nanowires, and thin films. However, a method that allows the large-scale production of silicon anodes remains to be demonstrated. Herein, we address this question by suggesting new scalable nanomaterial-based anodes. Si nanoparticles were grown on nanographite flakes by aerogel fabrication route from Si powder and nanographite mixture using polyvinyl alcohol (PVA). This silicon-nanographite aerogel electrode has stable specific capacity even at high current rates and exhibit good cyclic stability. The specific capacity is 455 mAh g−1 for 200th cycles with a coulombic efficiency of 97% at a current density 100 mA g−1.

  • 50.
    Rastabi, Shahrzad Arshadi
    et al.
    Tarbiat Modares University, Tehran, Iran.
    Mamoory, Rasoul Sarraf
    Tarbiat Modares University, Tehran, Iran.
    Blomquist, Nicklas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Phadatare, Manisha R.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Synthesis of a NiMoO4/3D-rGO nanocomposite via starch medium precipitation method for supercapacitor performance2020Inngår i: Batteries, ISSN 2313-0105, Vol. 6, nr 1, artikkel-id 5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents research on the synergistic effects of nickel molybdate and reduced graphene oxide as a nanocomposite for further development of energy storage systems. An enhancement in the electrochemical performance of supercapacitor electrodes occurs by synthesizing highly porous structures and achieving more surface area. In this work, a chemical precipitation technique was used to synthesize the NiMoO4/3D-rGO nanocomposite in a starch media. Starch was used to develop the porosities of the nanostructure. A temperature of 350◦C was applied to transform graphene oxide sheets to reduced graphene oxide and remove the starch to obtain the NiMoO4/3D-rGO nanocomposite with porous structure. The X-ray diffraction pattern of the NiMoO4 nano particles indicated a monoclinic structure. Also, the scanning electron microscope observation showed that the NiMoO4 NPs were dispersed across the rGO sheets. The electrochemical results of the NiMoO4/3D-rGO electrode revealed that the incorporation of rGO sheets with NiMoO4 NPs increased the capacity of the nanocomposite. Therefore, a significant increase in the specific capacity of the electrode was observed with the NiMoO4/3D-rGO nanocomposite (450 Cg−1 or 900 Fg−1) when compared with bare NiMoO4 nanoparticles (350 Cg−1 or 700 Fg−1) at the current density of 1 A g−1. Our findings show that the incorporation of rGO and NiMoO4 NP redox reactions with a porous structure can benefit the future development of supercapacitors. 

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