The advancements in 3D printing systems together with medical imaging devices, including magnetic resonance imaging (MRI) and computed tomography (CT), have made it possible to fabricate customized implantable scaffolds from computer-aided designs (CAD), which can precisely fit to the affected region in body of patients. [1,2] Hydrogels are widely preferred scaffold materials for 3D printing since they can mimic the natural tissues due to their high water content, porosity, and flexibility. [1,3] Additionally, they can be easily functionalized with biochemical and biophysical cues, and have easy fabrication processes. [4,5] Deriving therapeutic benefits such as supporting cell adhesion, promoting cell proliferation, and providing mechanical support for the tissue remodeling are desired for hydrogels. Physical, chemical, or biochemical crosslinking of homopolymer or copolymer solutions is typically used to form the hydrogels. [6] Along with synthetic polymers, the natural polymeric hydrogels can provide a stable environment for cells to grow, migrate, proliferate, and/or differentiate. [1] Natural polymers can be extracted from natural products via physical or chemical techniques in order to form hydrogels. The natural polymeric hydrogels, such as gelatin, [7,8] alginate, [9] fibrinogen, [10] hyaluronic acid, [11] cellulose, [12] and chitosan, [13] can dissolve in biofriendly inorganic solvents including phosphate-buffered saline (PBS) and cell culture medium. [6] Besides the well-known biocompatibility and biodegradability of natural polymeric hydrogels, their mechanical characteristics, however, limit potential applications as bioinks for manufacturing of scaffolds through 3D printing process. [14] Collagen-based biomaterials, used in most of the previous studies due to their intrinsic cell-adhesion sites, have been reported to have poor printability and long crosslinking durations. [15] Likewise, sodium alginate, which is a block copolymer of consecutive and alternately arranged β-d-mannuronic acid and α-l-guluronic acid residues, is a broadly preferred material since it is easily crosslinked via ionotropic gelation with divalent cations (e.g., Ca 2+ , Zn 2+). [16] However, alginate hydrogels require additional bioactivation step to trigger cell adhesion. [17] Another 3D bioprinting of hydrogels has gained great attention due to its potential to manufacture intricate and customized scaffolds that provide favored conditions for cell proliferation. Nevertheless, plain natural hydrogels can be easily disintegrated, and their mechanical strengths are usually insufficient for printing process. Hence, composite hydrogels are developed for 3D printing. This study aims to develop a hydrogel ink for extrusion-based 3D printing which is entirely composed of natural polymers, gelatin, alginate, and cellulose. Physicochemical interactions between the components of the intertwined gelatin-cellulose-alginate network are studied via altering copolymer ratios. The structure of the materials and porosity are assessed using infr...

on the requirements of the specifi c application and the compatibility of processing conditions with fi lm integration. There have been many more reports on the fabrication of Nd-Fe-B based fi lms [3][4][5] compared to Sm-Co based fi lms, [6][7][8][9][10] which may be attributed to a drive towards maximizing the remanence and thus the energy product of the hard magnetic fi lm. However, in certain applications where the hard magnetic fi lm is exposed to high demagnetizing fi elds and/or high operating temperatures, Sm-Co fi lms would be a better choice, due to the much higher values of magneto-crystalline anisotropy and thus high coercivity achievable in Sm-Co based materials. [11][12][13][14] We previously reported on the fabrication of high coercivity Sm-Co thin fi lms ( µ 0 H c ≤ 5 T at 300 K) by triode sputtering. [ 6 ] In this paper we demonstrate that the coercivity of Sm-Co based fi lms can be signifi cantly increased through a modifi cation of the target composition. With the aim to gain a better understanding of the origin of the high coercivity values, we carried out high-resolution microstructural characterization by using scanning transmission electron microscopy and atom probe tomography, and simulated the effect of the observed microstructural defects on magnetization reversal. While the high value of coercivity that was achieved could be relevant for particular applications, combined exploitation of recent advances in sample preparation, characterization, and modeling should contribute to the engineering of better bulk magnets. ResultsThe GI-XRD patterns of samples #1, #2, and #3 are shown in Figure 1 (note that all samples are amorphous in the asdeposited state -data not shown). Comparison of experimental peak positions with powder diffraction data fi les indicates that the crystal structure of the annealed fi lms changes from SmCo 1:7 to 1:5 and then to 2:7 as the Sm content of the layer is increased. Hereafter, samples "#1", "#2", and "#3" will be identifi ed as fi lms of 1:7, 1:5, and 2:7, respectively. Corresponding c / a ratios of 0.82, 0.795, and 0.808 were calculated from XRD peak positions for 1:7, 1:5, and 2:7, respectively. These values are quite close to the actual values for 1:7, 1:5, and 2:7 phases, namely 0.816, 0.793, and 0.803, respectively. [ 15 ] The as-deposited fi lms show soft magnetic behavior ( Figure 2 a). Room temperature in-plane hysteresis loops of

Single crystal SmCo5 nanoparticles with an average size of 3.5 nm are produced by cluster-beam deposition. When deposited without matrix, the nanoparticles showed a super-paramagnetic behavior with a blocking temperature of 145 K. Dispersion of the SmCo5 nanoparticles in a carbon matrix results in an increase in both the coercivity and the blocking temperature. Room temperature coercivities as high as 12 kOe are obtained for the first time in mono-layers of SmCo5 nanoparticles dispersed in C matrix. δM plots show that the interactions in the samples are of exchange type, which can decrease the overall effective anisotropy and coercivity according to the random-anisotropy model. Coercivity is found to be inversely proportional to the packing density of the particles. SmCo5 nanoparticles with high coercivity are potential candidates for the next generation ultra-highdensity magnetic recording media.

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