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Koppolu, R., Lahti, J., Abitbol, T., Swerin, A., Kuusipalo, J. & Toivakka, M. (2019). Continuous Processing of Nanocellulose and Polylactic Acid into Multilayer Barrier Coatings. ACS Applied Materials and Interfaces, 11(12), 11920-11927
Open this publication in new window or tab >>Continuous Processing of Nanocellulose and Polylactic Acid into Multilayer Barrier Coatings
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2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 12, p. 11920-11927Article in journal (Refereed) Published
Abstract [en]

Recent years have seen an increased interest toward utilizing biobased and biodegradable materials for barrier packaging applications. Most of the abovementioned materials usually have certain shortcomings that discourage their adoption as a preferred material of choice. Nanocellulose falls into such a category. It has excellent barrier against grease, mineral oils, and oxygen but poor tolerance against water vapor, which makes it unsuitable to be used at high humidity. In addition, nanocellulose suspensions' high viscosity and yield stress already at low solid content and poor adhesion to substrates create additional challenges for high-speed processing. Polylactic acid (PLA) is another potential candidate that has reasonably high tolerance against water vapor but rather a poor barrier against oxygen. The current work explores the possibility of combining both these materials into thin multilayer coatings onto a paperboard. A custom-built slot-die was used to coat either microfibrillated cellulose or cellulose nanocrystals onto a pigment-coated baseboard in a continuous process. These were subsequently coated with PLA using a pilot-scale extrusion coater. Low-density polyethylene was used as for reference extrusion coating. Cationic starch precoating and corona treatment improved the adhesion at nanocellulose/baseboard and nanocellulose/PLA interfaces, respectively. The water vapor transmission rate for nanocellulose + PLA coatings remained lower than that of the control PLA coating, even at a high relative humidity of 90% (38 °C). The multilayer coating had 98% lower oxygen transmission rate compared to just the PLA-coated baseboard, and the heptane vapor transmission rate reduced by 99% in comparison to the baseboard. The grease barrier for nanocellulose + PLA coatings increased 5-fold compared to nanocellulose alone and 2-fold compared to PLA alone. This approach of processing nanocellulose and PLA into multiple layers utilizing slot-die and extrusion coating in tandem has the potential to produce a barrier packaging paper that is both 100% biobased and biodegradable.

Keywords
barrier coatings, multilayer coatings, nanocellulose, polylactic acid, roll-to-roll process, Adhesion, Cellulose, Coatings, Extrusion, High speed cameras, Humidity control, Multilayers, Oxygen, Packaging materials, Polyesters, Suspensions (fluids), Water vapor, Yield stress, High relative humidities, Microfibrillated cellulose, Multi-layer-coating, Oxygen transmission rates, Poly lactic acid, Water vapor transmission rate
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-38266 (URN)10.1021/acsami.9b00922 (DOI)2-s2.0-85063139115 (Scopus ID)
Available from: 2019-04-02 Created: 2019-04-02 Last updated: 2019-06-28Bibliographically approved
Eriksson, M., Tuominen, M., Järn, M., Claesson, P. M., Wallqvist, V., Butt, H.-J., . . . Swerin, A. (2019). Direct Observation of Gas Meniscus Formation on a Superhydrophobic Surface. ACS Nano, 13(2), 2246-2252
Open this publication in new window or tab >>Direct Observation of Gas Meniscus Formation on a Superhydrophobic Surface
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2019 (English)In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 13, no 2, p. 2246-2252Article in journal (Refereed) Published
Abstract [en]

The formation of a bridging gas meniscus via cavitation or nanobubbles is considered the most likely origin of the submicrometer long-range attractive forces measured between hydrophobic surfaces in aqueous solution. However, the dynamics of the formation and evolution of the gas meniscus is still under debate, in particular, in the presence of a thin air layer on a superhydrophobic surface. On superhydrophobic surfaces the range can even exceed 10 μm. Here, we report microscopic images of the formation and growth of a gas meniscus during force measurements between a superhydrophobic surface and a hydrophobic microsphere immersed in water. This is achieved by combining laser scanning confocal microscopy and colloidal probe atomic force microscopy. The configuration allows determination of the volume and shape of the meniscus, together with direct calculation of the Young-Laplace capillary pressure. The long-range attractive interactions acting on separation are due to meniscus formation and volume growth as air is transported from the surface layer.

Keywords
AFM colloidal probe, capillary forces, laser scanning confocal microscopy, superhydrophobicity, wetting
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-37821 (URN)10.1021/acsnano.8b08922 (DOI)30707561 (PubMedID)
Available from: 2019-03-01 Created: 2019-03-01 Last updated: 2019-06-28Bibliographically approved
Wojas, N., Swerin, A., Wallqvist, V., Järn, M., Schoelkopf, J., Gane, P. & Claesson, P. M. (2019). Iceland spar calcite: Humidity and time effects on surface properties and their reversibility. Journal of Colloid and Interface Science, 541, 42-55
Open this publication in new window or tab >>Iceland spar calcite: Humidity and time effects on surface properties and their reversibility
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2019 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 541, p. 42-55Article in journal (Refereed) Published
Abstract [en]

Understanding the complex and dynamic nature of calcite surfaces under ambient conditions is important for optimizing industrial applications. It is essential to identify processes, their reversibility, and the relevant properties of CaCO3 solid-liquid and solid-gas interfaces under different environmental conditions, such as at increased relative humidity (RH). This work elucidates changes in surface properties on freshly cleaved calcite (topography, wettability and surface forces) as a function of time (≤28 h) at controlled humidity (≤3–95 %RH) and temperature (25.5 °C), evaluated with atomic force microscopy (AFM) and contact angle techniques. In the presence of humidity, the wettability decreased, liquid water capillary forces dominated over van der Waals forces, and surface domains, such as hillocks, height about 7.0 Å, and trenches, depth about −3.5 Å, appeared and grew primarily in lateral dimensions. Hillocks demonstrated lower adhesion and higher deformation in AFM experiments. We propose that the growing surface domains were formed by ion dissolution and diffusion followed by formation of hydrated salt of CaCO3. Upon drying, the height of the hillocks decreased by about 50% suggesting their alteration into dehydrated or less hydrated CaCO3. However, the process was not entirely reversible and crystallization of new domains continued at a reduced rate.

Keywords
Calcium carbonate minerals, Capillary forces, Humidity effects, Iceland spar calcite, Nanomechanical properties, Recrystallization, Reversibility of aging effects, Surface topography, Surface wettability, Van der Waals forces, Atomic force microscopy, Calcite, Calcium carbonate, Contact angle, Crystallization, Humidity control, Hydration, Phase interfaces, Surface properties, Wetting, Aging effects, Capillary force, Iceland spars, Nanomechanical property
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-37696 (URN)10.1016/j.jcis.2019.01.047 (DOI)2-s2.0-85060193864 (Scopus ID)
Note

 Funding details: Vetenskapsrådet, VR, 2015-05080; Funding text 1: Omya International AG provided financial funding of this research. Per M. Claesson acknowledges a grant from the Swedish Research Council (VR) [grant number 2015-05080 ].

Available from: 2019-02-01 Created: 2019-02-01 Last updated: 2019-06-17Bibliographically approved
Niga, P., Hansson-Mille, P., Swerin, A., Claesson, P. M., Schoelkopf, J., Gane, P., . . . Johnson, M. (2019). Propofol adsorption at the air/water interface: a combined vibrational sum frequency spectroscopy, nuclear magnetic resonance and neutron reflectometry study. Soft Matter, 15(1), 38-46
Open this publication in new window or tab >>Propofol adsorption at the air/water interface: a combined vibrational sum frequency spectroscopy, nuclear magnetic resonance and neutron reflectometry study
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2019 (English)In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 15, no 1, p. 38-46Article in journal (Refereed) Published
Abstract [en]

Propofol is an amphiphilic small molecule that strongly influences the function of cell membranes, yet data regarding interfacial properties of propofol remain scarce. Here we consider propofol adsorption at the air/water interface as elucidated by means of vibrational sum frequency spectroscopy (VSFS), neutron reflectometry (NR), and surface tensiometry. VSFS data show that propofol adsorbed at the air/water interface interacts with water strongly in terms of hydrogen bonding and weakly in the proximity of the hydrocarbon parts of the molecule. In the concentration range studied there is almost no change in the orientation adopted at the interface. Data from NR show that propofol forms a dense monolayer with a thickness of 8.4 Å and a limiting area per molecule of 40 Å2, close to the value extracted from surface tensiometry. The possibility that islands or multilayers of propofol form at the air/water interface is therefore excluded as long as the solubility limit is not exceeded. Additionally, measurements of the 1H NMR chemical shifts demonstrate that propofol does not form dimers or multimers in bulk water up to the solubility limit.

Keywords
Cytology, Dimers, Hydrogen bonds, Interferometry, Molecules, Neutron reflection, Nuclear magnetic resonance, Nuclear magnetic resonance spectroscopy, Reflection, Reflectometers, Solubility, Air/Water Interfaces, Concentration ranges, Interfacial property, Neutron reflectometry, NMR chemical shifts, Solubility limits, Surface tensiometry, Vibrational sum-frequency spectroscopies, Phase interfaces
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-37020 (URN)10.1039/C8SM01677A (DOI)2-s2.0-85058894693 (Scopus ID)
Note

Funding details: U.S. Department of the Interior, TEST-2589; Funding details: Institute for Translational Neuroscience, ITN;

Available from: 2019-01-17 Created: 2019-01-17 Last updated: 2019-03-07Bibliographically approved
Koppolu, R., Abitbol, T., Kumar, V., Jaiswal, A. K., Swerin, A. & Toivakka, M. (2018). Continuous roll-to-roll coating of cellulose nanocrystals onto paperboard. Cellulose (London), 25(10), 6055-6069
Open this publication in new window or tab >>Continuous roll-to-roll coating of cellulose nanocrystals onto paperboard
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2018 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 10, p. 6055-6069Article in journal (Refereed) Published
Abstract [en]

There is an increased interest in the use of cellulose nanocrystal (CNC) films and coatings for a range of functional applications in the fields of material science, biomedical engineering, and pharmaceutical sciences. Most of these applications have been demonstrated on films and coatings produced using laboratory-scale batch processes, such as solvent casting, dip coating, or spin coating. For successful coating application of CNC suspensions using a high throughput process, several challenges need to be addressed: relatively high viscosity at low solids content, coating brittleness, and potentially poor adhesion to the substrate. This work aims to address these problems. The impact of plasticizer on suspension rheology, coating adhesion, and barrier properties was quantified, and the effect of different pre-coatings on the wettability and adhesion of CNC coatings to paperboard substrates was explored. CNC suspensions were coated onto pre-coated paperboard in a roll-to-roll process using a custom-built slot die. The addition of sorbitol reduced the brittleness of the CNC coatings, and a thin cationic starch pre-coating improved their adhesion to the paperboard. The final coat weight, dry coating thickness, and coating line speed were varied between 1–11 g/m2, 900 nm–7 µm, and 2.5–10 m/min, respectively. The barrier properties, adhesive strength, coating coverage, and smoothness of the CNC coatings were characterized. SEM images show full coating coverage at coat weights as low as 1.5 g/m2. With sorbitol as plasticizer and at coat weights above 3.5 g/m2, heptane vapor and water vapor transmission rates were reduced by as much as 99% and 75% respectively. Compared to other film casting techniques, the process employed in this work deposits a relatively thick coating in significantly less time, and may therefore pave the way toward various functional applications based on CNCs.

Keywords
Barrier films, Barrier properties, Cellulose nanocrystals (CNCs), Roll-to-roll coating, Slot coating, Sorbitol plasticizer, Adhesion, Alcohols, Batch data processing, Biomedical engineering, Brittleness, Cellulose, Cellulose derivatives, Cellulose films, Fracture mechanics, Nanocrystals, Paperboards, Plasticity, Plasticizers, Reinforced plastics, Rolls (machine components), Substrates, Suspensions (fluids), Thickness measurement, Cellulose nano-crystals, Cellulose nanocrystal (CNC), Cellulose nanocrystal (CNCs), Functional applications, Roll to Roll, Water vapor transmission rate, Coatings
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-34488 (URN)10.1007/s10570-018-1958-1 (DOI)2-s2.0-85050341471 (Scopus ID)
Available from: 2018-08-08 Created: 2018-08-08 Last updated: 2018-12-12Bibliographically approved
Swerin, A. (2018). Dimensional Scaling of Aqueous Ink Imbibition and Inkjet Printability on Porous Pigment Coated Paper-A Revisit. Industrial & Engineering Chemistry Research, 57(49), 16684-16691
Open this publication in new window or tab >>Dimensional Scaling of Aqueous Ink Imbibition and Inkjet Printability on Porous Pigment Coated Paper-A Revisit
2018 (English)In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 57, no 49, p. 16684-16691Article in journal (Refereed) Published
Abstract [en]

A recently published dimensional scaling of infiltration of water-based inkjet fluids was used to revisit published inkjet printability data on mineral-pigment-based, inkjet-receptive coated papers. The dimensional scaling was developed using simple fluids on homogeneous isotropic media and applied on uncoated papers using complex inkjet fluids but so far has not been related to printability. It is shown that the scaling can also work for coated papers using commercial dye- and pigment-based inks with a suggested relation to printability as given by the color gamut area, in which the primary factor is the product of permeability and capillary pressure. A successful scaling suggests that inkjet printability can be predicted from flow and materials parameters, namely, porosity, viscosity, imbibed volume, permeability, and capillary pressure, and would be of general applicability in other areas of inkjet printing. The results further imply the usefulness of the approach in other functional surface modification using waterborne procedures on hard or soft porous materials.

Keywords
Capillarity, Capillary tubes, Paper, Pigments, Porous materials, Surface treatment, Coated paper, Functional surfaces, Isotropic media, Materials parameters, Mineral pigments, Primary factors, Simple fluids, Uncoated paper, Ink
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-36678 (URN)10.1021/acs.iecr.8b03868 (DOI)2-s2.0-85058090641 (Scopus ID)
Available from: 2018-12-21 Created: 2018-12-21 Last updated: 2019-06-28Bibliographically approved
Swerin, A. & Brandner, B. D. (2018). Interaction in cellulosic fiber-fiber joints at humid and wet conditions by AFM and confocal Raman microscopy. In: : . Paper presented at 2018 TAPPI International Conference on Nanotechnology for Renewable Materials, 11 June 2018 through 14 June 2018 (pp. 64-73).
Open this publication in new window or tab >>Interaction in cellulosic fiber-fiber joints at humid and wet conditions by AFM and confocal Raman microscopy
2018 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Interactions in fiber-fiber joints: • Interaction in crossed cellulosic fiber joints between was studied by atomic force colloidal probe microscopy (AFM) and mapping of surfaces and bonding sites using confocal Raman microspectroscopy (CRM) • CRM imaged surfaces and joints on thermomechanical pulp fibers, bleached pulp fibers and rayon fibers • Chemical and structural constituents relevant for bonding at high enough resolution can be imaged • Differences due to stresses or strains at, or close to, the fiber-fiber bonded area was detected but could not be evaluated. • Clean rayon fibers and bleached kraft pulp fibers, attached to an AFM cantilever and to the edge of an AFM chip, were brought in contact in a 90° crossed configuration • Forces measured in humid air and in water during approach and during retract • Bleached kraft pulp fiber-fiber joints can measured combined in adhesion and friction • Rayon fibers at different RH's give influence of capillary attraction at cross-points. Adhesion values significantly less than predicted by capillary attraction, due to roughness.

Keywords
Adhesion, Atomic force microscopy, Bleached pulp, Bleaching, Chemical bonds, Cleaning, Elasticity, Kraft pulp, Nanotechnology, Rayon, Structural design, Thermomechanical pulp, Thermomechanical pulping process, AFM cantilevers, Bleached kraft pulps, Capillary attraction, Cellulosic fibers, Colloidal probes, Confocal Raman microscopy, Confocal Raman microspectroscopy, Wet conditions, Fiber bonding
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-37714 (URN)2-s2.0-85060450011 (Scopus ID)9781510870369 (ISBN)
Conference
2018 TAPPI International Conference on Nanotechnology for Renewable Materials, 11 June 2018 through 14 June 2018
Available from: 2019-02-01 Created: 2019-02-01 Last updated: 2019-08-12Bibliographically approved
Niga, P., Hansson-Mille, P. M., Swerin, A., Claesson, P. M., Schoelkopf, J., Gane, P. A., . . . Johnson, C. M. (2018). Interactions between model cell membranes and the neuroactive drug propofol.. Journal of Colloid and Interface Science, 526, 230-243
Open this publication in new window or tab >>Interactions between model cell membranes and the neuroactive drug propofol.
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2018 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 526, p. 230-243Article in journal (Refereed) Published
Abstract [en]

phospholipid, NR data reveal that propofol is located exclusively in the head group region, which is rationalized in the context of previous studies. The results imply a non-homogeneous distribution of propofol in the plane of real cell membranes, which is an inference that requires urgent testing and may help to explain why such low concentration of the drug are required to induce general anaesthesia.

Keywords
Langmuir trough, Model membrane, Neutron reflectometry, Phospholipid monolayers, Propofol, Small amphiphilic drug, Surface pressure isotherm, Vibrational sum frequency spectroscopy
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33920 (URN)10.1016/j.jcis.2018.03.052 (DOI)29734090 (PubMedID)2-s2.0-85046641029 (Scopus ID)
Available from: 2018-06-07 Created: 2018-06-07 Last updated: 2019-01-09Bibliographically approved
Reverdy, C., Belgacem, N., Moghaddam, M. S., Sundin, M., Swerin, A. & Bras, J. (2018). One-step superhydrophobic coating using hydrophobized cellulose nanofibrils. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 544, 152-158
Open this publication in new window or tab >>One-step superhydrophobic coating using hydrophobized cellulose nanofibrils
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2018 (English)In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 544, p. 152-158Article in journal (Refereed) Published
Abstract [en]

Superhydrophobic surfaces have high potential in self-cleaning and anti-fouling applications. We developed a one-step superhydrophobic coating formulation containing sodium oleate (NaOl), hydrophobized precipitated calcium carbonate and biobased cellulose nanofibrils (CNFs) hydrophobized with either alkyl ketene dimer (AKD) or amino propyl trimethoxy silane (APMS) as a binder to fix and distribute the particles. Coatings were made on paperboard and the wetting behavior of the surface was assessed. Static, advancing and receding contact angles with water as well as roll-off and water shedding angle were compared to coatings made with styrene butadiene latex as binder instead of CNFs. Modifications with alkyl ketene dimer showed most promising results for a viable process in achieving superhydrophobic paperboard but required reformulation of the coating with optimized and reduced amount of NaOl to avoid surfactant-induced wetting via excess NaOl. A static water contact angle of 150° was reached for the CNF-AKD. The use of CNFs enables the improvement of coating quality avoiding cracking with the use of nanocellulose as a renewable binder.

Keywords
Cellulose nanofibrils, Paperboard, Superhydrophobicity, Binders, Bins, Calcium carbonate, Cellulose, Coatings, Contact angle, Nanofibers, Paperboards, Sodium Carbonate, Styrene, Wetting, Advancing and receding contact angles, Cellulose nanofibrils (CNFs), Precipitated calcium carbonate, Styrene butadiene latices, Super-hydrophobic surfaces, Superhydrophobic coatings, Hydrophobicity, 1, 3 butadiene, dimer, ketene derivative, latex, nanofiber, oleate sodium, silane derivative, surfactant, water, Article, chemical modification, material coating, priority journal, scanning electron microscopy, water absorption, Cellulose Fibers, Coating, Crazing, Dimers, Sodium Compounds
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33423 (URN)10.1016/j.colsurfa.2017.12.059 (DOI)2-s2.0-85042307822 (Scopus ID)
Note

Funding details: ANR-16-CARN-0025-01, Association Instituts Carnot; Funding details: ANR-11-LABX-0030, Labex; Funding details: COST, European Cooperation in Science and Technology; Funding details: AIR, American Institutes for Research; Funding details: Stiftelsen Nils och Dorthi Troëdssons Forskningsfond;

Available from: 2018-03-09 Created: 2018-03-09 Last updated: 2019-01-02Bibliographically approved
MacKenzie, J., Söderberg, D., Swerin, A. & Lundell, F. (2018). Turbulent stress measurements of fibre suspensions in a straight pipe. Physics of fluids, 30(2), Article ID 025104.
Open this publication in new window or tab >>Turbulent stress measurements of fibre suspensions in a straight pipe
2018 (English)In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 30, no 2, article id 025104Article in journal (Refereed) Published
Abstract [en]

The focus of the present work is an experimental study of the behaviour of semi-dilute, opaque fibre suspensions in fully developed cylindrical pipe flows. Measurements of the normal and turbulent shear stress components and the mean flow were acquired using phase-contrast magnetic resonance velocimetry. Two fibre types, namely, pulp fibre and nylon fibre, were considered in this work and are known to differ in elastic modulus. In total, three different mass concentrations and seven Reynolds numbers were tested to investigate the effects of fibre interactions during the transition from the plug flow to fully turbulent flow. It was found that in fully turbulent flows of nylon fibres, the normal, uzuz+, and shear, uzur+ (note that · is the temporal average, u is the fluctuating velocity, z is the axial or streamwise component, and r is the radial direction), turbulent stresses increased with Reynolds number regardless of the crowding number (a concentration measure). For pulp fibre, the turbulent stresses increased with Reynolds number when a fibre plug was present in the flow and were spatially similar in magnitude when no fibre plug was present. Pressure spectra revealed that the stiff, nylon fibre reduced the energy in the inertial-subrange with an increasing Reynolds and crowding number, whereas the less stiff pulp fibre effectively cuts the energy cascade prematurely when the network was fully dispersed.

Keywords
Magnetic resonance, Pipe flow, Polyamides, Rayon, Reynolds number, Shear flow, Shear stress, Turbulent flow, Concentration measures, Cylindrical pipes, Fibre interactions, Fluctuating velocities, Inertial subrange, Phase-contrast magnetic resonances, Pressure spectrum, Turbulent shear stress, Fibers
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33444 (URN)10.1063/1.5008395 (DOI)2-s2.0-85042207370 (Scopus ID)
Available from: 2018-03-09 Created: 2018-03-09 Last updated: 2018-08-14Bibliographically approved
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-6394-6990

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