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Non-renormalizable Newton maps are rigid. More precisely, we prove that their Julia sets carry no invariant line fields and that a topological conjugacy between them is equivalent to a quasiconformal conjugacy. [ABSTRACT FROM AUTHOR]

The low concentration of prepared cellulose nanofibril (CNF) suspension limits its large-scale application. In this study, bleached hardwood kraft pulp without any pretreatment was prepared into a CNF suspension with a concentration of about 1.0 wt% by a Supermasscolloider. The CNF suspension was dewatered by centrifugation to obtain concentrated CNFs (labeled 1-CNF). The 1-CNF sample was then mixed with water and dispersed by a high-speed homogenizer and dewatered again to obtain re-concentrated CNFs (labeled 2-CNF). The results showed that the suspension stability, water retention value and specific surface area of redispersed CNFs decreased compared to the unconcentrated CNFs. The cavities or pores formed by nanofibrils in the dewatering process were evaluated by the content of freezing bound water (FBW) that was calculated by differential scanning calorimetry with an isothermal step melting procedure. Pores were not observed in the starting unconcentrated CNFs, while the pores with a size of 0–395.8 nm were found in the two concentrated CNF samples (1-CNF and 2-CNF). The FBW content of the CNF samples increased as the solid content of the two concentrated CNFs increased. After re-concentration, the FBW content of 2-CNF decreased compared to that of 1-CNF. In sum, the concentration process of CNF suspension promoted the formation of pores and pores with small size formed first. However, in the re-dispersion and re-concentration process, the formed pores partially collapsed and shrunk. [ABSTRACT FROM AUTHOR]

Dewatering or drying of diluted cellulose nanofibril suspensions is an effective way for reducing the costs of transportation and storage. In this study, poly(vinylpyrrolidone) (PVP) was introduced into a redispersing system of concentrated CNFs, and the obtained redispersed CNFs were used for fabricating CNF/PANI (polyaniline) nanomaterials by in situ polymerization method. The results showed that mechanical grinding with grinding gap of − 20 μm was an effective way to redisperse the concentrated CNFs, especially when the PVP was added in the redispersing process. The conductivity of the redispersed CNF/PANI film reached 1.08 S/cm and the specific capacitance reached 118.3 F/g (at 0.3 A/g), when the concentrated CNFs were redispersed with 5% PVP. During the polymerization process, PVP facilitated the PANI coating on the CNFs uniformly as steric stabilizer. This study provided a basis for the application of redispersed CNFs in conductive nanomaterials area. [ABSTRACT FROM AUTHOR]

Nanocellulose, a unique and promising nanosized cellulose fibers extracted from renewable biomass, has gained much attention from both the scientific and industrial communities due to abundant resources, good mechanical properties, distinct surface chemistry, and biological properties. Thus, nanocellulose is a appealing biomaterial for exciting applications, including super absorbent materials, electronic components, energy devices, and reinforcements. Cellulose nanocrystal (CNC), cellulose nanofibril (CNF), and bacterial cellulose (BC) are the three main kinds of typical nanocellulose from different routes, thus the comprehensive comparison of CNC, CNF, and BC is highly desirable. In order to better understand their special characteristics, we have described detailedly of CNC, CNF (including TEMPO oxidized CNF and mechanically ground CNF), and BC in current work. Meanwhile, this study systematically compared their preparation method, morphologies, chemical structure, surface chemistry, degree of polymerization, thermal behavior, mechanical property, and so on, all these are good for understanding the structure–property–function relationships of nanocellulose. The systematic comparative study can help to develop the criteria for selecting proper nanocellulose as biobased nanomaterials for high value-added applications. We believe that these detailed information presented here have the potential to achieve true sustainable, economic, and tailored production of nanocellulose at large scale, thus contributing to the advancement of biobased nanocellulose. [ABSTRACT FROM AUTHOR]

Lignocellulosic nanofibrils (LCNFs) are usually isolated from biomass with concentration less than 2.0 wt%. The low concentration limits the transportation and end-use applications of LCNFs. Therefore, the development of concentration process and the characteristics of concentrated LCNF become desirable and important for commercial deployment of LCNF application. In this study, 1.0 wt% LCNF suspension was prepared by mechanical fibrillation using a supermass grinder after enzymatic pretreatment, and then dewatered to solid concentrations of 5.9 wt%, 16.3 wt% and 25.9 wt% by a centrifuge. The un-concentrated LCNF suspension was obviously stable, being translucent, and well dispersed in water, while the concentrated LCNF suspensions exhibited the gel-like behavior or "solid-like" behavior depending on the concentration. Bundle-like fibrils were observed for the concentrated LCNFs, and average diameter of concentrated LCNF became large but still less than 100 nm. Un-concentrated and concentrated LCNFs had similar crystallinity and crystallite size, and the morphological changes were mainly in the amorphous regions of the fibrils. The concentrated LCNF films still had relatively good UV-blocking property, water absorption and oxygen permeability. The increasing basis weight of films was benefit for enhancing the surface smoothness of films and interweaves between fibrils, resulting in the tensile index and specific modulus of films higher than 71.7 kN·m·kg−1 and 6.8 MN·m·kg−1, respectively. In sum, the concentration process affected the morphology structure of LCNF, but the concentrated LCNF still kept relatively good properties. Concentration process of LCNF suspension may be a feasible strategy for large-scale LCNF production and storage. [ABSTRACT FROM AUTHOR]

Having the advantages of a higher yield, lower cost and less environmental impact, lignin-containing cellulose nanofibrils (LCNFs) obtained by mechanically fibrillating unbleached pulps have been demonstrated to be a promising alternative to high-purity nanocellulose. In this study, the structural changes after four drying methods containing freeze-drying (FD), oven-drying (OD), centrifugal followed by vacuum-drying (CVD), and evaporation followed by vacuum-drying (EVD), and efficient reuse of LCNFs were extensively explored. It was found that the structural characteristics of LCNFs after drying were maintained by freeze drying with high lignin contents where the aggregation of fibrils was alleviated by lignin. The freeze-dried LCNFs were further redispersed by homogenizer in water, which exhibited excellent dispersion characteristics. In addition, the redispersed LCNFs were further assembled into PVA films to fabricate high-strength composites. The results showed that when the addition of redispersed LCNFs was up to 16.9%, the tensile strength and elongation at break of the as-prepared composite film increased by 325.2% and 335.2%, respectively. This study demonstrated a more sustainable approach to utilize LCNFs to produce biomass-based composite films than those of CNF-based composite films. [ABSTRACT FROM AUTHOR]

This study aims to investigate the relationship between mechanical fibrillation, morphological properties, and rheological behavior of cellulosic fiber. Three types of cellulosic fibers were obtained by adjusting mechanical fibrillation, namely squashed cellulose, incompletely nanofibrillated cellulose, and completely nanofibrillated cellulose, respectively. The squashed cellulose with large size and small aspect ratio had low entanglement capacity, thus forming a weak fiber network. The corresponding suspension exhibited low viscosity, weak elastic behavior, small yield stress, and low dynamic stability. An obviously increasing aspect ratio and entanglement capacity were observed with increasing mechanical fibrillation, resulting in entangled fiber network structure. Hence, the cellulosic fiber suspension obtained by more mechanical fibrillation exhibited higher viscosity, stronger gel-like behavior, and bigger yield stress. Moreover, the extremely entangled fiber network structure has better anti-deformation capacity and recovery capacity. We revealed the fundamental insights into the relationship between morphologies and rheological properties of cellulosic fiber, paving the way for designing cellulose-based materials. [ABSTRACT FROM AUTHOR]

Recycled paper and some hardwood paper often display poorer mechanical properties, which hinder its practical applications and need to be addressed. In this work, cellulose nanofibrils (CNFs) obtained by a combined process of enzymatic hydrolysis and grinding (EG-CNFs), grinding and microfluidization (GH-CNFs) or TEMPO-mediated oxidation and grinding (TE-CNFs) were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Moreover, CNFs were made into films on which some characterizations including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and UV–Vis transmittance spectroscopy were implemented. Results showed that CNF fibrillation was promoted as times of passes increased in microfluidization, and CNFs pretreated by enzyme possessed shorter length. Crystallinity of CNFs was related to CNF manufacturing methods, while CNF films' transparency was correlated to CNF diameter distributions. Moreover, CNFs were applied with different dosages on recycled and hardwood paper. Lengths of CNFs, strength of CNF network, and pulp properties were critical factors affecting the mechanical strength of CNFs-enhanced paper. GH-CNFs showed better strengthened effect on tensile strength of paper than TE-CNFs and EG-CNFs. The best overall improvement was achieved at GH-CNF10 dosage of 5.0 wt% on hardwood paper. The increment of tensile index, burst index, and folding endurance were 108.32%, 104.65%, and 600%, respectively. This work aims to find out the relationship between production methods and morphologies of CNFs and how the morphological characteristics of CNFs affecting the mechanical performance of paper when they are added as strength additives. [ABSTRACT FROM AUTHOR]

The aim of this work is to study and compare the morphology and rheology of cellulose nanofibrils (CNFs) from bleached softwood kraft pulp by several mechanical treatment methods. Three different kinds of CNFs were prepared in this work: (i) ones produced by PFI milling and microfluidic homogenization (RM-CNFs), (ii) ones produced by grinding and microfluidic homogenization (GM-CNFs), and (iii) ones produced by ball milling and ultrasonication (BU-CNFs). RM-CNFs had a high aspect ratio and the highest viscosity, storage modulus, and loss modulus. GM-CNFs had homogeneous size distributions, but low aspect ratio due to severe shearing of narrower orifice of chamber in microfluidic homogenization process. For BU-CNFs, the size distributions were heterogeneous, but they had a high aspect ratio. The three kinds of CNFs all had a lower crystallinity index than BSKP, and the degree of polymerization decreased with the increase of treatment intensity. Results of rheology measurements showed that those CNFs had a high degree of fibrillation and had a wider linear viscoelastic region in oscillatory strain measurements. Also the CNFs with high aspect ratio had a high viscosity and modulus. Additional treatments did not always increase the viscosity and modulus due to too severe treatments, which could cause the decrease of aspect ratio of CNFs. The RM-CNFs had a high viscosity and modulus, which means they are suitable in applications of rheology control. [ABSTRACT FROM AUTHOR]

We describe an effective method to create nanocomposites of silver nanoparticles that were stabilized by cellulose nanofibrils (CNF-AgNPs) that were then mixed with a starch matrix. The incorporation of CNF-AgNPs nanocomposites significantly enhanced the mechanical and antibacterial properties of hybrid films. The starch-based films with only 5.0 wt% CNF-AgNPs content exhibited superior mechanical properties in which the Young's modulus increased from 80.3 to 381.5 MPa and tensile strength increased from 6.06 to 9.96 MPa at 50% RH. Taking advantage of the denser microstructure and strong interfibrillar networks, the nanocomposite film can resist more external tensile forces and show excellent barrier property and thermostability. Moreover, antibacterial analysis indicated that CNF-AgNPs/starch nanocomposite films exhibited strong bactericidal effects against representative both Escherichia coli and Staphylococcus aureus. The cell viability of 87.71% and clear morphologies of live cells implied good biocompatibility of nanocomposite films. The demonstrated characteristics of CNF-AgNPs/starch nanocomposite film verified its suitability as a sustainable material for food packaging. [ABSTRACT FROM AUTHOR]

Plant fiber isolated cellulose nanofibers (CNFs) are the materials with excellent mechanical properties. However, application of CNFs in polymer reinforcement is normally unsatisfactory due to its intertwined size distribution. Efforts to produce uniform sized CNFs have yet to be studied. In present work, spiral microchannel was used to fractionate CNFs based on the balance between inertial lift force (FL) and Dean drag force (FD) exerted on CNFs. The results showed that the smaller length of CNFs equilibrated near the inner microchannel while the larger length of CNFs occupied the equilibrium position away from the inner wall. With the increase of flowrates from 50 to 220 μL/min, fractionation efficiency between inner and middle outlet (EIM) of spiral microchannel A with larger radius curvature (R) from 5 to 15 mm increased from 0 to 75.4%. However, stronger Dean flow attributing to decrease of R (3 mm to 10 mm) of single spiral microchannel B enabled satisfactory fractionation efficiency of 70.9% at flowrate of 90 μL/min. Moreover, the fractionation efficiency of double spiral microchannel with twice as length as microchannel A and three times as length as microchannel B was lower than that of single spiral microchannel at flowrate lower than 90 μL/min. Furthermore, this study exhibited a versatile and simple method for CNFs fractionation with high fractionation efficiency. [ABSTRACT FROM AUTHOR]

The microstructure and properties of lignocellulosic fibers usually change during the drying process due to the hornification of fibers. The water retention ability of fibers is an effective way to reflect the degree of fiber hornification. In this study, the effects of lignin content on the microstructural properties of dried-redispersed LCNFs (DLCNFs) were extensively explored. The results showed that the high content of lignin could maintain the microstructural integrity of DLCNFs. The water retention value and hornification degree of high lignin content DLCNFs (22.1%, w/w) were 289.8% and 6.9%, which were much lower than those of low lignin content (6.2%, w/w) DLCNFs. This was probably because that the crosslinking between lignin and carbohydrate effectively prevented the hydrogen bonding formation in the interior-fibers and exterior-fibers, and reduced the irreversible hornicficatoin of LCNFs. This study will be beneficial for the development of the LCNF drying mechanism. [ABSTRACT FROM AUTHOR]

Lipstick is a kind of popular cosmetic, which can give the lip a beautiful color and improve its appearance. The problem is that dye molecules would be in contact with the skin, whereas the lipstick made with dyed CNCs (CNC-lipstick) would reduce the contact. Herein, we demonstrated that the deficiency of color migration can be overcome by using the cellulose nanocrystal (CNC) dye to replace conventional dye in the lipstick substrates. The lipstick containing CNC dye (CNC-lipstick) could effectively inhibit the color migration and was easily erased as compared to ordinary lipsticks. The color change on the scoured skin was as high as ΔE* = 30.4 after using red ordinary dye-lipstick for 8 h, and red residue was clearly observed in the texture of the skin. Further cleaned with makeup remover, the color change on the scoured skin was ΔE* = 6.4. Notably, the color change of CNC-lipstick was ΔE* < 5, and only a small amount of red residue could be observed in the texture of the skin. The reduction of color migration from the lipstick to the skin was probably due to the fact that the dye absorbed by the CNC, which slowed down the diffusion rate of dye molecules. Our work paves the way for using CNC dye for inhibiting color migration in the lipstick application. Cellulose nanocrystals were applied to prepare the color easy-cleaned lipstick. [ABSTRACT FROM AUTHOR]

Based on the distortion theory developed by Cui and Tan (2015), we prove the landing of every parameter ray at critical portraits coming from non-recurrent polynomials, thereby generalizing a result of Kiwi (2005). [ABSTRACT FROM AUTHOR]

Ginsenosides are the major active components of ginseng, which have been proven to be effective in therapies for neurodegenerative diseases. Ginsenoside Rb1 (GS-Rb1) is the most abundant among all the identified ginsenosides and has been shown to exert neuroprotective effects, although the underlying molecular mechanisms remain unclear. Connexins are a family of transmembrane proteins that form gap junctions, which are important for diffusion of cytosolic factors such as ions and second messenger signaling molecules. Previous studies have shown that a subset of connexin proteins is involved in neuroprotection. We investigated the protective effects of GS-Rb1 against traumatic brain injury (TBI) and the potential mechanism using TBI mouse model. We discovered that TBI-induced brain injury and up-regulation of connexin40 (Cx40) protein expression as early as 6 h post-TBI, which was reversed by administration of GS-Rb1. In addition, we found that the protective effects of GS-Rb1 are dose and time dependent and are partially mediated through phosphorylation of ERK1/2 signaling pathway, as evidenced by the abolishment of GS-Rb1-mediated elevation of p-ERK1/2 expression and inhibition of Cx40 expressions when ERK inhibitor U0126 was used. Our study provides evidence that Cx40 is implicated in TBI-induced brain injuries, and GS-Rb1 exerts neuroprotective activity against TBI involving down-regulation of Cx40 expression. [ABSTRACT FROM AUTHOR]

Ginsenosides, the major bioactive compounds in ginseng root, have been found to have antioxidant, immunomodulatory, and anti-inflammatory activities. In the present study, we sought to investigate whether and how ginsenoside Rb1 (GS-Rb1), the most abundant ginsenoside, can protect blood-brain barrier (BBB) integrity following cerebral ischemia in middle cerebral artery occlusion (MCAO) animal model. ICR mice underwent MCAO and received GS-Rb1 by intraperitoneal injection at 3 h after reperfusion. We evaluated infarction, neurological scores, brain edema, Evans blue (EB) extravasation, and tight junction protein expression at 48 h after MCAO. We further examined whether GS-Rb1 protected BBB integrity by suppressing post-ischemic inflammation-induced activity of matrix metalloproteinase-9 (MMP-9) and nicotinamide adenine dinucleotide phosphate oxidase (NOX). First, GS-Rb1 decreased infarction and improved neurological deficits in MCAO animals. In addition, GS-Rb1 reduced EB extravasation and brain edema and preserved expression of tight junction proteins in the ischemic brain. Moreover, GS-Rb1 inhibited expression of pro-inflammatory factors including nitric oxide synthase and IL-1β, but increased expression of anti-inflammatory markers arginase 1 and IL-10 in the ischemic brain. Consistently, GS-Rb1 attenuated ischemia-induced expression and activity of MMP9. Finally, GS-Rb1 reduced NOX-4 mRNA expression and NOX activity in ischemic brain. These results suggest that GS-Rb1 protects loss of BBB integrity in ischemic stroke by suppressing neuroinflammation induction of MMP-9 and NOX4-derived free radicals, and indicate its potential for treating brain injuries, such as ischemia and stroke. [ABSTRACT FROM AUTHOR]