The traditional approach toward improving the crystallization rate as well as the mechanical and barrier properties of poly(lactic acid) (PLA) is the incorporation of nanocelluloses (NCs). ...Unfortunately, little study has been focused on the influence of the differences in NC morphology and dimensions on the PLA property enhancement. Here, by HCOOH/HCl hydrolysis of lyocell fibers, microcrystalline cellulose (MCC), and ginger fibers, we unveil the preparation of cellulose nanospheres (CNS), rod-like cellulose nanocrystals (CNC), and cellulose nanofibers (CNF) with different aspect ratios, respectively. All the NC surfaces were chemically modified by Fischer esterification with hydrophobic formate groups to improve the NC dispersion in the PLA matrix. This study systematically compared CNS, CNC, and CNF as reinforcing agents to induce different kinds of heterogeneous nucleation and reinforce the effects on the properties of PLA. The incorporation of three NCs can greatly improve the PLA crystallization ability, thermal stability, and mechanical strength of nanocomposites. At the same NC loading level, the PLA/CNS showed the highest crystallinity (19.8 ± 0.4%) with a smaller spherulite size (33 ± 1.5 μm), indicating that CNS, with its high specific surface area, can induce a stronger heterogeneous nucleation effect on the PLA crystallization than CNC or CNF. Instead, compared to PLA, the PLA/CNF nanocomposites gave the largest Young’s modulus increase of 350 %, due to the larger aspect ratio/rigidity of CNF and their interlocking or percolation network caused by filler–matrix interfacial bonds. Furthermore, taking these factors of hydrogen bonding interaction, increased crystallinity, and interfacial tortuosity into account, the PLA/CNC nanocomposite films showed the best barrier property against water vapor and lowest migration levels in two liquid food simulates (well below 60 mg kg–1 for required overall migration in packaging) than CNS- and CNF-based films. This comparative study was very beneficial for selecting reasonable nanocelluloses as nucleation/reinforcing agents in robust-barrier packaging biomaterials with outstanding mechanical and thermal performance.
Abstract
Structurally tunable electronic skin (e‐skin) is beneficial for advancing wearable electronics, prosthetics, and human‐machine interaction (HMI). However, the regulation of e‐skin by ...traditional nanostructure technology is complex and expensive, moreover, the nanostructure's poor deformability leads to small detection range and low sensitivity. Herein, inspired by the structure of skin‐hair and insect burr, a polypyrrole‐silk/glycerol plasticized silk fibroin (P‐silk/RG) e‐skin fabricated by a simple 3D biomimetic structural strategy is reported. Benefitting from the editability (length, position) of this structure, P‐silk/RG has a signal selectivity, long‐cilia P‐silk/RG demonstrates high sensitivity (respond to weak signal‐airflow), while the short‐cilia P‐silk/RG exhibits wide pressure detection range (0.5–200 g) and high cycle stability (8000 compressions). Therefore, different forms of P‐silk/RG are used in different scenarios (long‐cilia for monitoring breathing and coughing for motion detection and disease diagnosis, short‐cilia for pressure‐sensitive Morse code). Besides, P‐silk/RG exhibits good waterproof, editable conductive points and easy device integration, providing the basis for underwater information transmission, multibit coded command output, and early warning for emergency sports accidents and sedentary. Surprisingly, combining this structure with textile weaving can be mass‐produced. Obviously, this 3D biomimetic structure strategy endows e‐skin with editability and improved scene adaptability to provide a favorable way for mass production.
Cellulose dissolution is a worldwide issue in the production industry. Especially, the development of highly efficient and green cellulose solvents has been considered as a key factor to restrict the ...broad application of different cellulose industries. In this study, different chloride salts, such as LiCl, ZnCl2, CaCl2, and FeCl3, with different water amounts were used as green solvents to investigate the driving force of cellulose dissolution. The superfast and highly efficient cellulose dissolution in ZnCl2·3H2O and FeCl3·6H2O was successfully achieved within 5–20 min, which was confirmed by the results of polarized light microscopy. Moreover, the effect of pH and water amounts of the chloride salts on the cellulose structural change and dissolution ability was investigated for a better understanding of the role of chloride salts during the cellulose dissolution process. Especially, the dissolution mechanism of cellulose in ZnCl2·3H2O and FeCl3·6H2O has been provided compared to other non-derivatizing cellulose solvents.
ABSTRACT We use about 200,000 FGK-type main-sequence stars from the LAMOST DR1 data to map the local stellar kinematics. With the velocity deprojection technique, we are able to derive the averaged ...three-dimensional velocity and velocity ellipsoids using only the line-of-sight velocity for the stars with various effective temperatures within pc. Using the mean velocities of the cool stars, we derive the solar motion of ( , , ) = (9.58 2.39, 10.52 1.96, 7.01 1.67) with respect to the local standard of rest. Moreover, we find that the stars with K show a net asymmetric motion of ∼3 in compared to the stars with K. And their azimuthal velocity increases when increases. This peculiar motion in the warmer stars is likely because they are young and not completely relaxed, although other reasons, such as the resonance induced by the central rotating bar or the spiral structures and the perturbation of the merging dwarf galaxies, cannot be ruled out. The derived velocity dispersions and cross-terms for the data are approximately consistent with previous studies. We also find that the vertical gradients of and are larger than that of . And the vertical gradient of shows a clear correlation with , while the other two do not. Finally, our sample shows a vertex deviation of about at pc, but roughly zero at pc.
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•Functionalized cellulose nanocrystals (CNCs) for dye absorption.•Selective binding of methylene blue by polydopamine-CNC.•ITC analysis confirmed the types of binding interactions.
In ...this study, cellulose nanocrystals (CNCs) were evaluated as potential adsorbents for the selective adsorption and separation of organic dyes mixtures (methylene blue (MB), with either methyl orange (MO) or rhodamine b (RB) or crystal violet (CV)). The role of surface functional groups on the dye-CNC interaction was examined using pristine and surface-functionalized CNCs, such polydopamine (PD) and melamine–formaldehyde (MF) coated CNCs (PD-CNCs and MF-CNCs respectively). Batch adsorption studies on MB/MO dye mixture showed that pristine CNCs bearing anionic sulfate ester groups exhibited preferential adsorption for MB, with a 85.78% adsorption efficiency. This preferential adsorption was further enhanced in the case of PD-CNCs, which showed 100% adsorption efficiency for MB. Additional studies on MB/RB and MB/CV dye mixtures confirmed that the improved selectivity of PD-CNCs towards MB is associated with the synergistic binding interactions, such as electrostatic attraction, π-π stacking, and hydrogen bonding. MF-CNCs with cationic amine groups displayed selective binding towards MO, an anionic dye. Also, PD-CNCs and MF-CNCs were found to completely separate MB and MO from a diluted MB/MO dye mixture. Isothermal titration calorimetry and dye flocculation experiments confirmed that the selective binding is associated with the surface-functionality of CNCs.
The fabrication of functional assemblies with defined structures through controllable molecular packing under physiological conditions is challenging. Here, modularly designed peptide‐cyanine ...conjugates that intracellularly self‐assembly into 1D columnar superstructures with controlled cyanine aggregation were designed, and they exhibit distinct imaging or photothermal properties. The peptide backbone is cleaved by caspase‐3/7 after entering the cells. Then the self‐assembled residue, with a double cyanine substitution (Pr‐2Cy), forms a P helical column in which H‐aggregated cyanine dyes show 3.4‐fold photothermal conversion efficiency compared to free ones. The self‐assembled residue with a single cyanine substitution (Pr‐1Cy) forms a loose column, in which cyanine dyes with undefined structure have a fluorescence quantum yield of up to 9.5 % (emission at 819 nm in H2O). This work provides a simple way to modify in vivo self‐assembled peptides with functional molecules for achieving desired bio‐applications.
The design of peptide‐cyanine conjugates that intracellularly self‐assemble into a one‐dimensional column with controlled cyanine aggregation exhibit distinct imaging or photothermal properties. Through rational molecular design, the assembly behavior of cyanine dyes is precisely regulated in biological systems, resulting in two kinds of assemblies with different properties. The relationship between structure and function has been studied in detail.
The fundamental stellar atmospheric parameters (Teff and log g) and 13 chemical abundances are derived for medium-resolution spectroscopy from Large Sky Area Multi-Object Fiber Spectroscopic ...Telescope (LAMOST) Medium Resolution Survey (MRS) data sets with a deep-learning method. The neural networks we designed, named SPCANet, precisely map LAMOST MRS spectra to stellar parameters and chemical abundances. The stellar labels derived by SPCANet have precisions of 119 K for Teff and 0.17 dex for log g. The abundance precision of 11 elements including C/H, N/H, O/H, Mg/H, Al/H, Si/H, S/H, Ca/H, Ti/H, Cr/H, Fe/H, and Ni/H are 0.06 ∼ 0.12 dex, while that of Cu/H is 0.19 dex. These precisions can be reached even for spectra with signal-to-noise ratios as low as 10. The results of SPCANet are consistent with those from other surveys such as APOGEE, GALAH, and RAVE, and are also validated with the previous literature values including clusters and field stars. The catalog of the estimated parameters is available at doi:10.12149/101012.
Textile manufacturing industries produce large amounts of viscose fiber wastes (VFW), causing serious environmental pollution. This study presents an acid-free approach to prepare spherical cellulose ...nanocrystals (SCNs) with carboxyl groups from industrial VFW by one-step hydrothermal ammonium persulfate (APS) oxidation. Novel double-response surface methodology was employed to optimize the reaction conditions. A maximum yield (37.89%) of carboxylated SCN was obtained at reaction time of 4 h, APS concentration of 1 M and temperature of 80 °C, while the SCNs showed gradual size reductions along with increase of carboxyl contents as reaction time and APS concentration increased. Interestingly, it was possible to obtain carboxylated SCNs in only 2 h of reaction with an increase of 16.5% in the crystallinity index, which was attributed to efficient swelling of cellulose chains and oxidation interaction of surface groups under hydrothermal condition. Compared with SCN-2 h, the crystallinity index and maximum degradation temperature of SCN-10 h were improved by 5.5% and 17.9 °C, respectively. Moreover, SCN-10 h exhibited excellent emulsifying capacity to stabilize soybean oil/water Pickering emulsion droplets and emulsion volume were increased with decreased mean diameter of emulsion droplets as SCN-10 h concentration increased. These results indicate that VFW is an attractive source to produce carboxylated SCNs by APS oxidation, making SCN extraction as value-added alternatives to recycle this waste. Such carboxylated SCNs have great potentials as green food Pickering emulsion stabilizers and nanofillers in high-performance composites.
In this study, conductive cellulose nanocrystals (CNCs) were coated with polypyrrole (PPy) using in situ chemical polymerization to form CNC-PPy conductive nano-network. The one-pot polymerization of ...“hard” segment methyl methacrylate (MMA) was continued onto above functionalized CNCs, then blended with “soft” molecular segment polyvinyl alcohol (PVA) to contain self-healing and conductive composite film (CPMV) fabricated by soft-hard network. In addition, the tensile strength of CPMV films with 2 wt% CNC-PPy was enhanced by 47.1%. Also, CPMV films exhibited self-healing properties due to the presence of hydrogen bonding dynamic network and showed sensitive resistance changes under external stimuli, which could be used to monitor various actions of the human body. Thus, the CPMV films present potential applications in electronic devices such as flexible electrodes, biosensors, and implantable devices.
•Cellulose nanocrystals coated with polypyrrole gave conductivity performance.•Functionalized CNCs with hard MMA chains reinforced the soft PVA composites films.•Soft-hard network contributed to robust mechanical strength of the composites.•PVA composites films showed excellent self-healing and sensing performances.
Objective
Our team designed a long‐lasting, well‐sealed microphone, which uses laser welding and vacuum packaging technology. This study examined the sensitivity and effectiveness of this new ...floating piezoelectric microphone (NFPM) designed for totally implantable cochlear implants (TICIs) in animal experiments and intraoperative testing.
Methods
Different NFPM frequency responses from 0.25 to 10 kHz at 90 dB SPL were analyzed using in vivo testing of cats and human patients. The NFPM was tested in different positions that were clamped to the ossicular chains or placed in the tympanic cavity of cats and human patients. Two volunteers' long incus foot and four cats' malleus neck of the ossicular chain were clamped with the NSFM. The output electrical signals from different locations were recorded, analyzed, and compared. The NFPM was removed after the test without causing any damage to the middle‐ear structure of the cats. Intraoperative tests of the NFPM were performed during the cochlear implant surgery and the cochlear implant surgery was completed after all tests.
Results
Compared with the results in the tympanic cavity, the NFPM could detect the vibration from the ossicular chain more sensitively in cat experiments and intraoperative testing. We also found that the signal output level of the NFPM decreased as the acoustic stimulation strength decreased in the intraoperative testing.
Conclusion
The NFPM is effective in the intraoperative testing, making it feasible as an implantable middle‐ear microphone for TICIs.
Level of Evidence
4 Laryngoscope, 134:937–944, 2024
This study examined the sensitivity and effectiveness of a new floating piezoelectric microphone (NFPM) designed for totally implantable cochlear implants (TICIs) in animal experiments and clinical trials. The NFPM is effective and without obvious body noise, making it feasible as an implantable middle‐ear microphone for TICIs.
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