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The authors would like to thank Ahmed and Prof. Mauri Kostiainen for help in cryo-TEM sample preparation and image acquisition and Dr. Leena Pitkänen for help toward GPC analysis. The authors would like to thank the Academy of Finland (project number 133355163 SA/COVID-19) for providing funding for this project. I.L. would like to thank Svenska Kulturfonden for the PhD scholarship. This work made use of the BIOECONOMY and OTANANO infrastructure at the Aalto University. Cationic polysaccharides have demonstrated significant antimicrobial properties and have great potential in medical applications, where the antiviral activity is of great interest. As of today, alcohols and oxidizing agents are commonly used as antiviral disinfectants. However, these compounds are not environmentally safe, have short activity periods, and may cause health issues. Therefore, this study aimed to develop metal-free and environmentally friendly quaternary chitosans (QCs) with excellent long-lasting virucidal activity. To evaluate this, both single and double QCs were obtained using AETMAC ([2-(acryloyloxy)ethyl]-trimethylammonium chloride) and GTMAC (glycidyl trimethylammonium chloride) quaternary precursors. Further, this study investigated the influence of the quaternary functional group, charge density, and molecular weight (Mw) on the antiviral properties of QCs. It is proposed that the higher charge density, along with the length of alkyl linkers, and hydrophobic interactions affected the antiviral activity of QCs. The findings demonstrated that heterogeneously functionalized chitosan exhibited excellent antiviral activity against both the enveloped virus φ6 and the nonenveloped viruses φX174 and MS2. These quaternized chitosan derivatives have promising potential as viable antiviral agents, as hand/surface sanitizers, or in other biomedical applications.

The authors would like to acknowledge financial support from Business Finland (7428/31/2022, PCMI project), the Academy of Finland; No. 343192 (SoMa), No. 327248 (ValueBiomat), and No. 327865 (Bioeconomy). The authors would also like to acknowledge the effort made by Dr. Ari Kankkunen on IR camera measurement. This study aimed to introduce a smart multifunctional textile composed of a phase change material, i.e., polyethylene glycol (PEG), with a potential for thermo-regulative biomedical application. PEG was efficiently form-stabilized with polycaprolactone, and the nanofibers mats were developed by electrospinning to overcome the PEG leakage issue during the phase change process. Gelatin and curcumin were also incorporated to enable the biomedical performance of the textiles. The results revealed that the electrospun nanofibers possessed randomly oriented morphology, sufficient water absorption capability, good mechanical properties, and excellent phase change performance. The fibers' diameter varied from 220 nm to 370 nm, with a tensile strength ranging from 10 to 30 MPa. Furthermore, the fabricated mats possessed a latent heat of 61.7 J/g and reliable energy absorption-release cyclability over 100 heating-cooling cycles. The curcumin-loaded textiles revealed an initial burst release followed by a sustained release over one week. They further presented a significant antioxidant activity of 81.23.7 ± 3.08 % after 24 h, introducing a great potential application as a biomedical dressing to diminish inflammation with a cooling effect.

The world's current energy crisis calls for green energy solutions that can preserve energy while incorporating renewable. As such, we have developed a leakage-proof phase change material (PCM) embedded in a biopolymeric matrix as a lightweight yet strong bio-based phase change composite (PCC) for passive energy storage and insulation purposes in packaging. This bio-based composite consists of gum tragacanth (GT) biopolymer and polyethylene glycol (PEG) PCM. It is further incorporated with biochar (BC) or mineral additive, i.e., Cloisite Na+, to enhance its mechanical strength and thermal stability, which are among the main challenges for insulation materials. A hydrophobic layer of octadecyl isocyanate (ODI) is developed on the surface of the composite to increase its water resistance. The composite provides a hydrophobic surface with a minor water uptake capacity of 3.6 ± 0.3 % after one-week immersion in the water. It shows high latent heat storage up to 160 J g−1 and a stable phase change behavior, as demonstrated by over 100 differential scanning calorimetry heating-cooling cycles. It also possesses notable compressive mechanical properties, which were improved significantly after incorporating BC and Cloisite Na+. The thermal conductivity of the composite is as low as 0.035 W m−1 K−1 manifesting in better thermal regulation compared with commercial polyethylene foams. This energy-positive bio-based solution combines the advantages of excellent insulation as a highly porous, lightweight, and strong composite with the latent heat and thermal inertia of PCM, making it suitable for transportation packaging of temperature-sensitive products.

The direction and magnitude of carbon dioxide fluxes between the atmosphere and the sea are regulated by the gradient in the partial pressure of carbon dioxide (pCO2) across the air–sea interface. Typically, observations of pCO2 at the sea surface are carried out by using research vessels and ships of opportunity, which usually do not resolve the diurnal cycle of pCO2 at a given location. This study evaluates the magnitude and driving processes of the diurnal cycle of pCO2 in a coastal region of the Baltic Sea. We present pCO2 data from July 2018 to June 2019 measured in the vicinity of the island of Utö at the outer edge of the Archipelago Sea, and quantify the relevant physical, biological, and chemical processes controlling pCO2. The highest monthly median of diurnal pCO2 variability (31 µatm) was observed in August and predominantly driven by biological processes. Biological fixation and mineralization of carbon led to sinusoidal diurnal pCO2 variations, with a maximum in the morning and a minimum in the afternoon. Compared with the biological carbon transformations, the impacts of air–sea fluxes and temperature changes on pCO2 were small, with their contributions to the monthly medians of diurnal pCO2 variability being up to 12 and 5 µatm, respectively. During upwelling events, short-term pCO2 variability (up to 500 µatm within a day) largely exceeded the usual diurnal cycle. If the net annual air–sea flux of carbon dioxide at our study site and for the sampled period is calculated based on a data subset that consists of only one regular measurement per day, the bias in the net exchange depends on the sampling time and can amount up to ±12 %. This finding highlights the importance of continuous surface pCO2 measurements at fixed locations for the assessment of the short-term variability of the carbonate system and the correct determination of air–sea CO2 fluxes.

In the present paper, the suitability of the selected oilseeds, their corresponding vegetable oils, and few other raw materials to produce bio-based plastics was evaluated by constructing a novel criteria-based framework for Multi-Criteria Decision-Making (MCDM) analysis with a focus on the criteria of chemical functionality, sustainability, production quantity, cost, and market availability. Qualitative, semi-quantitative, and quantitative data was utilized as a base for the criteria, for which a 1–5–9 scaling technique was developed to convert the hybrid starting data into the quantitative form, when required. Additionally, two varying sets of starting data, four scenarios with differing weights of importance, as well as two different MCDM techniques, namely Technique for Order Preference and Similarity to Ideal Solution (TOPSIS) and Simple Additive Weighting (SAW), were used as a form of sensitivity analysis. The MCDM results were influenced by the dissimilar algorithm of TOPSIS and SAW techniques, resulting in different level of accuracy and a phenomenon of rank reversal, together with the developed MCDM framework in terms of the utilized data types, scaling technique, assumptions to treat data uncertainty as well as the selected criteria and scenarios. Regardless of the different starting data sets, scenarios, and MCDM techniques utilized for the MCDM analysis, tall, linseed, soybean, and palm oil were identified as the most suitable and palm kernel, coconut, and sunflower oil as the least suitable raw materials with their feature trade-offs to produce bio-based plastics. The MCDM results of the present paper can be treated as a guidepost targeted for diverse actors in the early stage of the bio-based plastics’ value chain with varying point-of-views. Further, in the future, the novel MCDM framework can be of relevant significance in analysing the features of various raw materials to produce bio-based plastics.

Humic substances, a component of terrestrial dissolved organic matter (tDOM), contribute to dissolved organic matter (DOM) and chromophoric DOM (CDOM) in coastal waters, and have significant impacts on biogeochemistry. There are concerns in recent years over browning effects in surface waters due to increasing tDOM inputs, and their negative impacts on aquatic ecosystems, but relatively little work has been published on estuaries and coastal waters. Photodegradation could be a significant sink for tDOM in coastal environments, but the rates and efficiencies are poorly constrained. We conducted large-scale DOM photodegradation experiments in mesocosms amended with humic substances and nutrients in the Gulf of Finland to investigate the potential of photochemistry to remove added tDOM and the interactions of DOM photochemistry with eutrophication. The added tDOM was photodegraded rapidly, as CDOM absorption decreased and spectral slopes increased with increasing photons absorbed in laboratory experiments. The in situ DOM optical properties became similar among the control, humic- and humic+nutrients-amended mesocosm samples toward the end of the amendment experiment, indicating degradation of the excess CDOM/DOM through processes including photodegradation. Nutrient additions did not significantly influence the effects of added humic substances on CDOM optical property changes, but induced changes in DOM removal.

Business Finland Project (43674/31/2020) is acknowledged for the research funding to the current work. L.T. would like to thank the financial support to conduct research mobility at Åbo Akademi University (ÅAU) provided by Johan Gadolin Scholar mobility funding programme. Both L.W. and L.H. would like to acknowledge the financial support from the China Scholarship Council (Student ID 201804910639 for L.W. and Student ID 201908120107 for L.H.) to their doctoral study at ÅAU, Finland. Jarl Hemming and Dr. Annika Smeds are greatly acknowledged on their help with GPC and Py/GC–MS analysis. Qingbo Wang is thanked for his work with DMA measurements. Dr. Andrey Pranovich is thanked for discussing while initializing the project. CH-Bioforce Oy (Espoo, Finland) is thanked for providing birch and spruce ALs. This work is also part of activities within the Johan Gadolin Process Chemistry Centre (PCC) at ÅAU. This work also made use of Aalto University Bioeconomy Facilities. Two series of well-defined lignin fractions derived from birch and spruce alkaline lignin (AL) by sequential solvent fractionation (i-PrOH-EtOH-MeOH) were engaged in a structure–property-application relationship study. The bacterial-derived alkaliphilic laccase (MetZyme) extensively catalyzed the oxidation and polymerization of AL fractions in an aqueous alkaline solution (pH 10). Lignin fractions with low molar mass reached a higher polymerization degree due to more phenolic-OH groups serving as reactive sites of oxidation and better lignin-laccase accessibility arose from a lower lignin condensation degree than the high molar mass ones. In comparison, AL fractions from spruce were found to be less reactive toward the laccase-catalyzed polymerization than those from birch, which was attributed to the much pronounced aryl-vinyl moieties’ oxidation. Furthermore, in situ polymerization of birch AL fractions using microfibrillated cellulose as a structural template was conducted in an aqueous medium and a dispersion of nanocellulose with its fiber network evenly coated by aligned lignin nanoparticles was obtained. The present study not only provides fundamental insights on the laccase-assisted oxidation and polymerization of lignin but also presents a new perspective for valorizing lignin in biobased fiber products through green processing of solvent fractionation and enzymatic treatment.

Graphene family nanomaterials (GFNs) are rapidly emerging for ocular applications due to their outstanding physicochemical properties. Since the eyes are very sensitive organs and the contact between the eyes and GFNs in eye drops, contact lenses, intraocular drug delivery systems and biosensors and even the workers handling these nanomaterials is inevitable, it is necessary to investigate their ocular toxicities and physiological interactions with cells as well as their toxicity mechanisms. The toxicity of GFNs can be extremely affected by their physicochemical properties, including composition, size, surface chemistry, and oxidation level as well as dose and the time of exposure. Up to now, there are several studies on the in vitro and in vivo toxicity of GFNs; however, a comprehensive review on ocular toxicity and applications of GFNs is missing, and a knowledge about the health risks of eye exposure to the GFNs is predominantly unspecified. This review highlights the ocular applications of GFNs and systematically covers the most recent advances of GFNs’ physicochemical properties, in vitro and in vivo ocular toxicity, and the possible toxicity mechanisms as well as provides some perspectives on the potential risks of GFNs in material development and biomedical applications.

Lignin is introduced as a suitable component for selective laser sintering (SLS) of polyamide (PA12) to reduce costs while maintaining or improving processability and performance. Alkali lignin (sourced as a polydisperse, amorphous powder) was used at a volume concentration of up to 60 vol % for three-dimensional (3D) printing of complex, layered structures. The latter were obtained as high axial aspect objects, produced in flat, flipped (90°), and vertical directions, which were further examined to elucidate the effect of lignin as a suitable component in SLS. The composite withstood heating during SLS, and sintered PA/lignin showed 30% less degradation at elevated temperatures compared to pure PA. The morphological, wetting, mechanical, and thermal characteristics associated with the 3D-printed structures were compared. For instance, the strength and wettability were highly dependent on processing orientation. Compared to objects produced from neat PA, those that included lignin presented a higher porosity (∼10%) with a simultaneous increase in stiffness (increased Young modulus, by ∼16%, and reduced tensile strength, by ∼7%). Owing to differences in surface roughness and composition, an important difference in the water contact angle (CA) of the samples printed in the flipped and flat orientations was observed (55 and 126°, respectively). Overall, SLS is shown as a developmental step toward lignin valorization in composites while allowing reduced cost, scalability, and facile processing.

Biodegradable poly(carbonate anhydrides) based on poly(trimethylene carbonate) were synthesized by ring-opening polymerization. The hydroxyl-terminated oligomers were acid-functionalized with succinic anhydride and subsequently methacrylated to obtain photo-crosslinkable three-armed macromers with anhydride bonds. The degree of acid-functionalization was over 96%, and the degree of methacrylation was over 80%. The macromers were photo-crosslinked into networks at room temperature in a nitrogen atmosphere. In vitro degradation experiments in phosphate-buffered solution (pH 7.4) at 37 degrees C showed that the networks degraded rapidly with complete mass loss within 72 h. For networks prepared from the higher molecular weight, the presence of an alkenyl chain in the anhydride bond resulted in lower water uptake and consequently in a decrease in the degradation rate. The degradation mechanism of these networks showed characteristics of surface erosion.

Funding Information: The authors would like to thank the Magnus Ehrnrooth Foundation, Finnish Cultural Foundation, and Academy of Finland No. 307485 (3D-Biomat) for providing funding for this project. This work made use of the BIOECONOMY infrastructure at Aalto University. Publisher Copyright: © 2022 Conductive polymeric nanocomposites have made significant contributions in nerve regeneration. To this aim, the best results are obtained by using nerve guidance conduits (NGCs) with conductive, bio-compatible, bio-degradable tubes as well as special topographical features. In this study, biodegradable, conductive, solvent-free polyurethane/PEGylated graphene oxide (PU/PEG-GO) composites were synthesized and successfully 3D printed into flexible nerve conduits with different precise geometries, such as hollow, porous, and grooved tubes, using stereolithography. The composite containing 5% PEG-GO showed the highest tensile stress (3.51 ± 0.54 MPa), tensile strain at break (∼170%), and conductivity (1.1 × 10−3 S/cm) with the lowest contact angle of 72° attributing to the strong interfacial interactions between PEG-GO nanosheets and the PU matrix. Moreover, the PU/PEG-GO 5% exhibited higher compression strength compared with pure PU and showed appropriate enzymatic degradation after 6 weeks, which is expected tolast sufficiently for an efficient nerve regeneration. Altogether the 3D-printed, conductive, biodegradable, and flexible PU/PEG-GO 5% conduit with precise geometry has potential as NGCs for peripheral nerve regeneration.

The authors would like to acknowledge the Academy of Finland funding; No. 327248 (ValueBiomat) and 327865 (Bioeconomy). This work was a part of the Academy of Finland's Flagship Programme under Projects No. 318890 and 318891 (Competence Center for Materials Bioeconomy, FinnCERES). The authors would also like to thank the Biohybrid Materials Research Group (Aalto University) for providing the HepG2 cells. The current study provides a comprehensive rheology study and a survey on direct ink writing of xanthan gum/cellulose nanocrystal (XG/CNC) bio-inks for developing 3D geometries that mimic soft tissue engineering scaffolds' physical and mechanical properties. The presence of CNC was found to be a critical prerequisite for the printability of XG bio-inks; accordingly, the hybrid XG/CNC bio-inks revealed the excellent viscoelastic properties that enabled precise control of hydrogel shaping and printing of lattice structures composed of up to eleven layers with high fidelity and fair resolution without any deformation after printing. The lyophilized 3D scaffolds presented a porous structure with open and interconnected pores and a porosity higher than 70%, vital features for tissue engineering scaffolds. Moreover, they showed a relatively high swelling of approximately 11 g/g, facilitating oxygen and nutrient exchange. Furthermore, the elastic and compressive moduli of the scaffolds that enhanced significantly upon increasing CNC content were in the range of a few kPa, similar to soft tissues. Finally, no significant cell cytotoxicity was observed against human liver cancer cells (HepG2), highlighting the potential of these developed 3D printed scaffolds for soft tissue engineering applications.

The demand for optical components such as microlenses has been growing at a rapid rate in recent years. While conventional methods for manufacturing these components are well known, they are often time-consuming, detrimental for the environment and unable to keep up with the increasing demand. To overcome these issues, the technique of three-dimensional (3D) inkjet printing has attracted much attention. The aim of this review was to investigate the 3D inkjet printing process as a technique for the fabrication of microlenses and identify the key components and methodologies which can be used to control the properties of the resultant microlenses. 3D Inkjet printing was identified as a viable alternative for the production of microlenses owing to its high flexibility, scalability and efficiency as well as its ability to produce good quality products. Substrate modification was shown as a key method by which the geometric and optical properties of microlenses can be controlled. Organic materials such as acrylates and epoxies, and hybrid materials such as siloxanes were shown to be the most common base materials in photo-crosslinkable inkjet formulations and the effects of incorporation of organic compounds and inorganic nanoparticles on the material refractive index were studied.

Highlights • Modest brownification did not affect primary production, but increased bacterial production. • Concentration of inorganic nitrogen was the primary driver for the phytoplankton development. • Brownification benefitted picophytoplankton. Climate change is projected to cause brownification of some coastal seas due to increased runoff of terrestrially derived organic matter. We carried out a mesocosm experiment (15 d) to test the effect of this on the planktonic ecosystem expecting reduced primary production and shifts in the phytoplankton community composition. The experiment was set up in 2.2 m3 mesocosm bags using four treatments, each with three replicates: control (Contr) without any manipulation, organic carbon additive HuminFeed (Hum; 2 mg L−1), inorganic nutrients (Nutr; 5.7 μM NH4 and 0.65 μM PO4), and combined Nutr and Hum (Nutr + Hum) additions. Measured variables included organic and inorganic nutrient pools, chlorophyll a (Chla), primary and bacterial production and particle counts by flow cytometry. The bags with added inorganic nutrients developed a phytoplankton bloom that depleted inorganic N at day 6, followed by a rapid decline in Chla. Brownification did not reduce primary production at the tested concentration. Bacterial production was lowest in the Contr, but similar in the three treatments receiving additions likely due to increased carbon available for heterotrophic bacteria. Picoeukaryotes clearly benefited by brownification after inorganic N depletion, which could be due to more effective nutrient recycling, nutrient affinity, light absorption, or alternatively lower grazing pressure. In conclusion, brownification shifted the phytoplankton community composition towards smaller species with potential effects on carbon fluxes, such as sinking rates and export to the sea floor.

Funding Information: A.A.‐S and R.K. contributed equally to this work as first authors. R.S.‐K, J.S., and B.M. contributed equally to this work as senior authors. The project was funded by Business Finland (CraMaxS 557/31/2016) and was implemented in collaboration between University of Helsinki, Aalto University, and Helsinki University Hospital in cooperation with Planmeca Oy, DeskArtes Oy, Versoteq 3D Solutions Oy, and Labquality Oy. Additional funds from the in vivo study were also received from Helsinki University Hospital State funding for university‐level health research (Grant Nos. Y1149SUL30, Y1014SL015, Y1014SULE1, TYH2018225, and TYH2019117). The authors kindly thank Stryker Ltd for craniomaxillofacial instrumentation used in surgical procedures, Dr. Heikki Suhonen X‐Ray Micro‐CT Laboratory for µCT expertise, staff at Large Animal Center for animal care, Veterinary Teaching Hospital for CT imaging, Finnish Centre for Laboratory Animal Pathology (FCLAP) for histopathological services and Genome Biology Unit for histology scanning, and all part of HiLIFE University of Helsinki. Ashish Mohite from Aalto University School of ARTS supported the research with modelling expertise. This work made use of Aalto University Bioeconomy Facilities. Publisher Copyright: © 2022 The Authors. Macromolecular Bioscience published by Wiley-VCH GmbH A major challenge with extensive craniomaxillofacial bone reconstruction is the limited donor-site availability to reconstruct defects predictably and accurately according to the anatomical shape of the patient. Here, patient-specific composite bioimplants, consisting of cross-linked poly(trimethylene carbonate) (PTMC) networks and β-tricalcium phosphate (β-TCP), are tested in vivo in twelve Göttingen minipigs in a large mandibular continuity defect model. The 25 mm defects are supported by patient-specific titanium reconstruction plates and receive either osteoconductive composite bioimplants (PTMC+TCP), neat polymer network bioimplants (PTMC), autologous bone segments (positive control), or are left empty (negative control). Postoperatively, defects treated with bioimplants show evident ossification at 24 weeks. Histopathologic evaluation reveals that neat PTMC bioimplant surfaces are largely covered with fibrous tissue, while in the PTMC+TCP bioimplants, bone attached directly to the implant surface shows good osteoconduction and histological signs of osteoinductivity. However, PTMC+TCP bioimplants are associated with high incidence of necrosis and infection, possibly due to rapid resorption and/or particle size of the used β-TCP. The study highlights the importance of testing bone regeneration implants in a clinically relevant large animal model and at the in situ reconstruction site, since results on small animal models and studies in nonloadbearing areas do not translate directly.

The authors would like to acknowledge the Academy of Finland funding; No. 327248 (ValueBiomat) and 327865 (Bioeconomy). This work was a part of the Academy of Finland's Flagship Programme under Projects No. 318890 and 318891 (Competence Center for Materials Bioeconomy, FinnCERES). The authors would also like to thank Ms. Marja Kärkkäinen for providing TEMPO-CNF and the Biohybrid Materials Research Group (Aalto University) for providing the HepG2 cells. Plant-based hydrogels have attracted great attention in biomedical fields since they are biocompatible and based on natural, sustainable, cost-effective, and widely accessible sources. Here, we introduced new viscoelastic bio-inks composed of quince seed mucilage and cellulose nanofibrils (QSM/CNF) easily extruded into 3D lattice structures through direct ink writing in ambient conditions. The QSM/CNF inks enabled precise control on printing fidelity where CNF endowed objects with shape stability after freeze-drying and with suitable porosity, water uptake capacity, and mechanical strength. The compressive and elastic moduli of samples produced at the highest CNF content were both increased by ~100% (from 5.1 ± 0.2 kPa and 32 ± 1 kPa to 10.7 ± 0.5 and 64 ± 2 kPa, respectively). These values ideally matched those reported for soft tissues; accordingly, the cell compatibility of the printed samples was evaluated against HepG2 cells (human liver cancer). The results confirmed the 3D hydrogels as being non-cytotoxic and suitable to support attachment, survival, and proliferation of the cells. All in all, the newly developed inks allowed sustainable 3D bio-hydrogels fitting the requirements as scaffolds for soft tissue engineering.

Blending polymers with a high concentration of bio-based fillers is one of the solutions that not only reduces a dependency on petroleum-based feedstocks but can also significantly decrease the carbon footprint. In the current study, n-octadecyl isocyanate (ODI) molecules were grafted on lignin particles to render them compatible with a novel copolyamide matrix, which was successfully synthesized through a copolymerization between petroleum- and bio-based monomers. Different concentrations of the surface-modified particles were melt-blended with a low-melting point copolyimide, and the properties of the developed biocomposites being thoroughly studied. The SEM imaging revealed that the surface-modified particles homogeneously dispersed into the polymer matrix for all loading levels without any clear evidence of particle agglomeration, phase separation, or voids formation, proposing excellent compatibility between the components that arose from a successful surface modification process. Furthermore, the mechanical properties of the biocomposites significantly improved. For instance, the yield stress and tensile modulus were enhanced by 50% and 200% at the biocomposite with 50 wt% filler content, without any considerable change in the tensile strain. The dynamic mechanical analysis, as well as the rheology measurements, further confirmed the uniform dispersion of the surface-modified particles and their compatibility with the copolymer matrix, within which the storage modulus considerably improved upon the increase of filler content. Overall, our findings strongly suggest that these newly developed biocomposites with a green content of up to 80% are attractive candidates for substituting petroleum-based plastics for the demanded applications.

Funding Information: Dr. J.T. is grateful for the support of the Academy of Finland’s Flagship Programme under Projects Nos. 318890 and 318891 (Competence Center for Materials Bioeconomy, FinnCERES). The authors acknowledge the funding support by the Academy of Finland’s BioFuture2025 program under project 2228357-4 (3D Manufacturing of Novel Biomaterials) and the provision of facilities by Aalto University at OtaNano Nanomicroscopy Center (Aalto-NMC). The authors also acknowledge Ashish Mohite for the elaboration of the G-code for the honeycomb structure and Kari Kääriäinen for the post-processing of 3D-printed parts with a CNC machine. Publisher Copyright: © 2021 The Authors. Published by American Chemical Society. We developed a 3D-printing process based on thermoset biocomposites termed Delayed Extrusion of Cold Masterbatch (DECMA). DECMA is a processing method, based on controlling the degree of curing, that takes some responsibility of the 3D printing from materials and as such can be used to 3D print otherwise unprintable materials. First, a masterbatch was produced by mixing a bio-based resin (bioepoxy) and sawdust and lignin. This paste was partially cured at room temperature until reaching an apparent viscosity suitable for extrusion (≈105 mPa·s at 1 s-1). The system was next cooled (5-10 °C) to delay subsequent hardening prior to 3D printing. The printability of the biocomposite paste was systematically investigated and the merits of the delayed extrusion, via DECMA, were assessed. It was found that DECMA allowed the revalorization of sawdust and lignin via 3D printing, as direct printing led to failed prints. Our approach afforded cost-effective, shear-thinning dopes with a high bio-based content (58-71%). Thebio-based 3D-printed materials demonstrated good machinability by computer numerical control (CNC). Overall, the benefits of the introduced DECMA method are shown for processing bio-based materials and for on-demand solidification during additive manufacturing.

Implants of bioresorbable materials combined with osteoconductive calcium phosphate ceramics show promising results to replace and repair damaged bone tissue. Here we present additive manufacturing of patient-specific porous scaffolds of poly(trimethylene carbonate) (PTMC) including high amounts of β-tricalcium phosphate (β-TCP). Tensile testing of composite networks showed that addition of β-tricalcium phosphate reinforces the composites significantly. Three-dimensional structures containing up to 60 wt % β-TCP could be built by stereolithography. By lowering the content to 51 wt %, manufacturing of a large-sized patient-specific prototype was possible at high resolution. Closer examination revealed that the created scaffolds contained more β-TCP on the surface of the builds. Stereolithography therefore provides a manufacturing technique where the bioactive agent is directly available for creating an enhanced microenvironment for cell growth. The biocompatibility and bioresorption of PTMC coupled with the osteoconductivity of β-TCP are an important candidate to consider in additive manufacturing of bone regeneration implants.

Isocyanate-functionalised graphene (iGO) was prepared and incorporated into a thermoplastic polyurethane via an in situ polymerisation. Firstly, graphene oxide was successfully modified using a mix...

Three-dimensional (3D) printing of biomaterials has the potential to become an ecologically advantageous alternative compared with conventional manufacturing based on oil-derived polymer materials. In this study, a novel 3D printing technology is applied that combines ultraviolet (UV) curing with paste extrusion. This hybrid manufacturing technique enables the fabrication of complex geometries from high filler-ratio pastes. The developed biocomposite aims for suitable mechanical properties in terms of tensile and compressive strength. It is composed of acrylic acid, cellulose acetate, α-cellulose, and fumed silica with a cellulose ratio of more than 25 vol-%. The material is extruded with an in-house-developed 3D printer equipped with a 12 W UV light curing source, which enables concurrent curing and extrusion. Two different UV-curing strategies were tested: postcuring without concurrent curing and postcuring with concurrent curing. The total UV-curing duration was kept constant with all samples. Tensile testing in accordance with ASTM standard D638-14 Type 4, compression testing according to ASTM D695-15, and overhang tests were conducted. As a result, samples without notable shrinkage, suitable tensile strength (up to 17.72 MPa), competitive compression testing parameters (up to 19.73 MPa), and an enhanced overhang angle (increase of more than 25°) were produced, leading to new applications and more freedom in design due to higher possible unsupported overhangs when using UV-curing during the print. Overall, constant UV light radiation during the print leads to improved mechanical properties due to the possibility of bypassing the UV-penetration depth constraint. It should be considered when extruding photopolymer-based composites, especially for large and complex components with a low degree of translucency.

Non

The authors would like to acknowledge the Academy of Finland funding; No. 327248 (ValueBiomat), 327865 (Bioeconomy), and 307485 (3DBiomat, 3D Manufacturing of Novel Biomaterials). This work made use of the facilities of Aalto University's Nanomicroscopy Center. We proposed a simple method to process hydrogels containing polyvinyl alcohol and cellulose nanofibrils (PVA/CNF) to prepare volumetric architectures by direct ink writing (DIW). The presence of CNF in the aqueous PVA suspensions conferred rheology profiles that were suitable for extrusion and solidification in pre-designed shapes. The viscoelastic behavior of the hybrid inks enabled precise control on processability and shape retention, for instance, as demonstrated in multilayered lattice structures of high fidelity. After lyophilization, the obtained 3D-printed hydrogels presented a very high porosity, with open and interconnected pores, allowing a high-water uptake capacity (up to 1600%). The mechanical strength of the composite 3D-printed materials matched those of soft tissues, opening opportunities for skin applications. As such, drug-loaded samples revealed a controlled and efficient delivery of an antioxidant (ascorbic acid) in PBS buffer media at 23 °C (~80% for 8 h). Altogether, PVA/CNF hydrogels were introduced as suitable precursors of 3D-lattice geometries with excellent physical and mechanical characteristics.

A new kind of long-chain aliphatic polyamide (PA1218) with a relatively low melting point, high molecular weight, and stable mechanical properties at humid conditions was successfully developed via a polycondensation reaction between 1,18-octadecanedioic acid and 1,12-diaminodecane. Additionally, oleic acid-surfaced modified silicon dioxide (SSD) was prepared and employed to improve the properties of PA1218 through in-situ polymerization. FT-IR spectra and TGA thermograms confirmed the successful surface modification of nanoparticles, and consequently, 5% substitution of surface hydroxyl groups of SiO2 nanoparticles with oleic acid molecules. Moreover, the thermomechanical and rheology tests revealed a significant improvement in nanocomposites’ properties compared to the pure PA1218; for instance, the tensile strength and storage modulus were increased by 22% and 40%, respectively in the sample containing 3% SSD nanoparticles. This improvement, along with SEM images, confirmed the uniform dispersion of SSD nanoparticles through the employed in-situ polymerization and excellent compatibility between inorganic and organic phases, which was achieved via surface modification. Finally, all the samples demonstrated a water uptake capacity of less than 0.6% attributed to the high methylene/amide ratio in their backbones, causing these newly developed nanocomposites to be notable candidates for specific engineering applications.

The current study was performed to synthesize a series of renewable polyamide 614/organoclay nanocomposites (PAC) with the improved structural, mechanical, and thermal properties via in-situ polymerization. The uniform dispersion and exfoliation of clay into the PA614 matrix, particularly at a lower loading of organoclay (less than 3%), confirmed via structural analyses (XRD, SEM, and TEM). Furthermore, the mechanical tests revealed remarkable improvement; namely, the tensile strength and storage modulus increased by 27% and 30%, respectively, in the sample contained 2% organoclay. Similarly, the TGA results showed a slight improvement in the thermal stability of the nanocomposite samples. Altogether, these improvements confirmed excellent compatibility between nanofiller and matrix and the organoclay homogenous dispersion into the PA matrix achieved by employing in-situ polymerization. Furthermore, all the samples illustrated a shear-thinning behavior over frequency attributed to the lack of time for the polymer chain to respond to the applied oscillation. Finally, the crystallinity of the samples diminished upon increasing the filler's content, which could be due to the decrease of free volume resulting from the presence of organoclay. To sum up, the current investigation supported the benefit of employing in-situ polymerization to synthesize renewable PA614/clay nanocomposites with enhanced physio-mechanical properties, which could be appropriate candidates for engineering applications.

We present the in-situ biogeochemical data products distributed by the Copernicus Marine Service since 2018. The products offer available data of chlorophyll, oxygen, and nutrients (nitrate, silicate and phosphate), both in near-real time and as re-processed data, collected across the globe. The re-processing involves careful quality control utilizing tailored automated quality control procedures combined with visual inspection of questionable values by experts. Moreover, oxygen data are provided with uniform units for modelers (µmol/l) and other oceanic applications and monitoring purposes (µmol/kg) The products integrate observations aggregated from the Regional EuroGOOS consortium, as well as from SeaDataNet2, National Data Centers (NODCs) and JCOMM global systems, among others.We highlight some use cases, including a study showing an overall decline in the nutrient concentration (nitrate and silicate) of the Atlantic Water flowing though the Nordic Seas en-route to the Arctic Ocean, during the period 1990-2019. Moreover, the study shows indications of a delayed-response reduction further downstream in the Arctic Water exiting the Arctic Ocean through Fram Strait. Other use cases include the study of variability in the concentration of dissolved oxygen in the Mediterranean Sea, showing an association with dynamical processes.The in-situ near-real time biogeochemical product is updated every month whereas the re-processed product is updated two times per year. Products are delivered on NetCDF4 format compliant with the CF1.7 standard and well-documented quality control procedures.

Reduced graphene oxide (rGO) integrated nano-fibrillated cellulose (NFC) grafted poly(ionic liquid) (PIL) composite paper with enhanced hydrophobicity, ductility and toughness was fabricated by vacuum filtration of an aqueous dispersion of rGO/NFC-graft-PIL (NFC-g-PIL). The NFC-g-PIL was synthesized by growing PIL chains from the NFC surface using free radical polymerization of a pyridinium acrylate-based ionic liquid monomer. publishedVersion

There is a growing demand for marine omega-3 fatty acids (FAs) that is produced in high amounts by some microalgae. Here we determined the FA profiles of two cold water adapted diatoms,Chaetoceros wighamiiandThalassiosira baltica. The cultures were acclimated to different temperatures (3, 7, 11, 15, and 19 °C) and irradiance (20, 40, 130, and 450 μmol photons m−2s−1) and the FA profiles were determined in exponential and stationary growth phases, the latter induced by different nutrient limitation (N, P, and Si). The maximum growth rate was obtained by both species at 11 °C, ≥ 130 μmol photons m−2s−1and was 0.8 day−1and 0.6 day−1forC. wighamiiandT. baltica, respectively. Both species contained relatively high amounts of eicosapentaenoic acid (EPA).Thalassiosira balticaaccumulated maximally ~ 30 mg EPA g−1ash-free dry weight (AFDW) under Si-limitation. The content of docosahexaenoic acid (DHA) was lower, reaching up to 4 mg DHA g−1AFDW inT. baltica. The concentration of EPA correlated positively with the chlorophylla:carbon ratio, suggesting that it is bound to membranes in the photosynthetic apparatus and the EPA content inT. balticawas high enough to consider it as a potent candidate for cultivation under cold (< 15 °C) conditions. Covering a wide range of environmental conditions, the strongest differentiation in FA profiles was observed between the species with the growth phase/nutrient limitation pattern as the second most important driver of the FA composition.

The direction and magnitude of carbon dioxide exchange between the atmosphere and the sea is regulated by their difference in partial pressure of carbon dioxide (pCO2). Typically, observations of pCO2 are carried out by using research vessels and voluntary observing ships which cannot easily detect the diurnal cycle of pCO2 at a given location. This study evaluates the magnitude and driving processes of the diurnal cycle of pCO2 in a coastal region of the Baltic Sea during the different seasons.We present pCO2 data from July 2018–June 2019 carried out in the vicinity of the island of Utö in the Archipelago Sea and quantify the relevant physical, biological and chemical processes affecting pCO2. The highest monthly median diurnal pCO2 peak-to-peak amplitude (31 μatm) was observed in August. This high diurnal variation was found to be related predominantly to biological processes. The biological transformations of carbon generated a sinusoidal diurnal pCO2 variation, with a maximum in the morning and a minimum in the afternoon. Compared to the biological carbon transformations, the effect of air sea exchange of carbon dioxide and the effect of temperature changes on pCO2 are smaller, with their monthly median peak-to-peak amplitudes were up to 12 and 5 μatm, respectively. Single diurnal peak-to-peak amplitudes can be significantly larger (up to 500 μatm), during upwelling. If the net exchange of carbon dioxide between the sea and atmosphere on our study site and sampling period is calculated based on a data set that consists of only one measurement per day, the error in the budget depends on the sampling time and can be up to &pm;12 %.

Large critical size bone defects are complicated to treat, and in many cases, autografts become a challenge due to size and availability. In such situations, a synthetic bone implant that can be patient-specifically designed and fabricated with control over parameters such as porosity, rigidity, and osteogenic cues can act as a potential synthetic bone substitute. In this study, we produced photocuring composite resins with poly(trimethylene carbonate) containing high ratios of bioactive ceramics and printed porous 3D composite scaffolds to be used as bone grafts. To enhance the overall surface area available for cell infiltration, the scaffolds were also filled with a macroporous cryogel. Furthermore, the scaffolds were functionalized with osteoactive factors: bone morphogenetic protein and zoledronic acid. The scaffolds were evaluated in vitro for biocompatibility and for functionality in vivo in critical bone defects (∼8 mm) in two clinically relevant rabbit models. These studies included a smaller study in rabbit tibia and a larger study in the rabbit cranium. It was observed that the bioactive molecule-functionalized 3D printed porous composite scaffolds provide an excellent conductive surface inducing higher bone formation and improved defect healing in both critical size long bones and cranial defects. Our findings provide strong evidence in favor of these composites as next generation synthetic bone substitutes.

Additive manufacturing (AM) is gaining interests in drug delivery applications, offering innovative opportunities for the design and development of systems with complex geometry and programmed controlled release profile. In addition, polymer-based drug delivery systems can improve drug safety, efficacy, patient compliance, and are the key materials in AM. Therefore, combining AM and polymers can be beneficial to overcome the existing limitations in the development of controlled release drug delivery systems. Considering these advantages, here we are focusing on the recent developments in the field of polymeric drug delivery systems prepared by AM. This review provides a comprehensive overview on a holistic polymer–AM perspective for drug delivery systems with discussion on the materials, properties, design and fabrication techniques and the mechanisms used to achieve a controlled release system. The current challenges and future perspectives for personalized medicine and clinical use of these systems are alsobriefly discussed.

Plankton communities form the basis of aquatic ecosystems and elucidating their role in increasingly important environmental issues is a constantly present research question. The concealed plankton community dynamics reflect changes in environmental forcing, growth traits of competing species, and multiple food web interactions. Recent technological advances have led to the possibility of collecting real-time big data opening new horizons for testing core hypotheses in planktonic systems, derived from macroscopic realms, in community ecology, biodiversity research, and ecosystem functioning. Analyzing the big data calls for computer vision and machine learning methods capable of producing interoperable data across platforms and systems. In this paper we apply convolutional neural networks (CNN) to classify a brackish-water phytoplankton community in the Baltic Sea. For solving the classification task, we utilize compact CNN architectures requiring less computational capacity and creating an opportunity to quickly train the network. This makes it possible to (1) test various modifications to the classification method, and (2) repeat each experiment multiple times with different training and test set combinations to obtain reliable results. We further analyze the effect of large class imbalance to the CNN performance, and test relevant data augmentation techniques to improve the performance. Finally, we address the practical implications of the classification performance to aquatic research by analyzing the confused classes and their effect on the reliability of the automatic plankton recognition system, to guide further development of plankton recognition research. Our results show that it is possible to obtain good classification accuracy with relatively shallow architectures and a small amount of training data when using effective data augmentation methods even with a very unbalanced dataset.

In this work we present a green method to prepare aerogel membranes based on cellulose nanofibers (CNFs) crossed-linked with poly (ethylene imine) (PEI) and further decorated with silver nanoparticles (Ag NPs). The nanosized Ag NPs were reduced and immobilized on the surface of the pore walls inside the aerogel. The as-prepared composite aerogel membrane showed excellent continuous catalytic discoloration of aqueous cationic and anionic dye solutions in batch and flow filtration tests. Moreover, the aerogel membrane exhibited very stable catalytic activity with discoloration efficiency at as high as 98% after 10 times reuse and the water permeance was high, up to 5 × 10 4 L·m −2 h −1. Interestingly, the aerogel membrane showed excellent shape recovery in water and no obvious deterioration of the structure was observed during long time testing. Therefore, the obtained aerogel membranes showed great potential in waste water treatment and catalytic applications.