A Stable PDLC Film with High Ageing Resistance from an Optimized System Containing Rigid Monomer.

With the switchability between transparent and light-scattering states, polymer-dispersed liquid crystals (PDLC) are widely used as smart windows, flexible display devices, projectors, and other devices. In outdoor applications, in addition to excellent electro-optical properties, there is also a high demand for film stability. In this work, a PDLC film with high mechanical strength and structural stability is prepared that can maintain stability at 80 °C for 2000 h. By choosing liquid crystals with a wide temperature range, adopting acrylate polymer monomers containing hydroxyl groups, and adjusting the polymer content, the PDLC film can work well from -20 °C to 80 °C. On this basis, the effects of the introduction of rigid monomers on the mechanical properties and electro-optical properties of PDLC films are investigated.

Plant Cellulose Nanofiber-Derived Structural Material with High-Density Reversible Interaction Networks for Plastic Substitute.

Ubiquitous petrochemical-based plastics pose a potential threat to ecosystems. In response, bioderived and degradable polymeric materials are being developed, but their mechanical and thermal properties cannot compete with those of existing petrochemical-based plastics, especially those used as structural materials. Herein, we report a biodegradable plant cellulose nanofiber (CNF)-derived polymeric structural material with high-density reversible interaction networks between nanofibers, exhibiting mechanical and thermal properties better than those of existing petrochemical-based plastics. This all-green material has substantially improved flexural strength (∼300 MPa) and modulus (∼16 GPa) compared with those of existing petrochemical-based plastics. Its average thermal expansion coefficient is only 7 × 10-6 K-1, which is more than 10 times lower than those of petrochemical-based plastics, indicating its dimension is almost unchanged when heated, and thus, it has a thermal dimensional stability that is better than those of plastics. As a fully bioderived and degradable material, the all-green material offers a more sustainable high-performance alternative to petrochemical-based plastics.

Bio-Inspired Lotus-Fiber-like Spiral Hydrogel Bacterial Cellulose Fibers.

Hydrogel materials with high water content and good biocompatibility are drawing more and more attention now, especially for biomedical use. However, it still remains a challenge to construct hydrogel fibers with enough strength and toughness for practical applications. Herein, we report a bio-inspired lotus-fiber-mimetic spiral structure hydrogel bacterial cellulose fiber with high strength, high toughness, high stretchability, and energy dissipation, named biomimetic hydrogel fiber (BHF). The spiral-like structure endows BHF with excellent stretchability through plastic deformation and local failure, assisted by the breaking-reforming nature of the hydrogen bonding network among cellulose nanofibers. With the high strength, high stretchability, high energy dissipation, high hydrophilicity, porous structure, and excellent biocompatibility, BHF is a promising hydrogel fiber for biomedicine. The outstanding stretchability and energy dissipation of BHF allow it to absorb energy from the tissue deformation around a wound and effectively protect the wound from rupture, which makes BHF an ideal surgical suture.

Recent Advances in The Polymer Dispersed Liquid Crystal Composite and Its Applications.

Polymer dispersed liquid crystals (PDLCs) have kindled a spark of interest because of their unique characteristic of electrically controlled switching. However, some issues including high operating voltage, low contrast ratio and poor mechanical properties are hindering their practical applications. To overcome these drawbacks, some measures were taken such as molecular structure optimization of the monomers and liquid crystals, modification of PDLC and doping of nanoparticles and dyes. This review aims at detailing the recent advances in the process, preparations and applications of PDLCs over the past six years.

Liquid Crystal Elastomer Actuators from Anisotropic Porous Polymer Template.

Controlling self-assembly behaviors of liquid crystals is a fundamental issue for designing them as intelligent actuators. Here, anisotropic porous polyvinylidene fluoride film is utilized as a template to induce homogeneous alignment of liquid crystals. The mechanism of liquid crystal alignment induced by anisotropic porous polyvinylidene fluoride film is illustrated based on the relationship between the alignment behavior of liquid crystals and surface microstructure of anisotropic polyvinylidene fluoride film. Liquid crystal elastomer actuators with fast responsiveness, large strain change, and reversible actuation behaviors are achieved by the photopolymerization of liquid crystal monomer in liquid crystal cells coated with anisotropic porous films.

Polymer nanoparticles for controlled release stimulated by visible light and pH.

Polymer nanoparticles are prepared by self-assembly of visible light and pH sensitive perylene-functionalized copolymers which are synthesized by quaternization between 1-(bromomethyl)perylene and the dimethylaminoethyl units of poly(dimethylaminoethyl methacrylate) (PDMAEMA). The perylene-containing polymethacrylate segments afford the system visible light responsiveness and the unquaternized PDMAEMA segments afford the system pH responsiveness. The self-assembled nanoparticles exhibit a unique dual stimuli response. They can be photocleaved under visible light irradiation, shrunken to smaller nanoparticles at high pH, and swollen at low pH. The structural change endows the nanoparticle with great potential as a sensitive nanocarrier for controlled release of Nile Red and lysozyme under this stimulation. The visible light responsiveness and synergistic effect on the release of loaded molecules with the dual stimulation may obviate the need for harsh conditions such as UV light or extreme pH stimulation, rendering the system more applicable under mild conditions.

Knotted Artificial Muscles for Bio-Mimetic Actuation under Deepwater.

Muscles featuring high frequency and high stroke linear actuation are essential for animals to achieve superior maneuverability, agility, and environmental adaptability. Artificial muscles are yet to match their biological counterparts, due to inferior actuation speed, magnitude, mode, or adaptability. Inspired by the hierarchical structure of natural muscles, artificial muscles are created that are powerful, responsive, robust, and adaptable. The artificial muscles consist of knots braided from 3D printed liquid crystal elastomer fibers and thin heating threads. The unique hierarchical, braided knot structure offers amplified linear stroke, force rate, and damage-tolerance, as verified by both numerical simulations and experiments. In particular, the square knotted artificial muscle shows reliable cycles of actuation at 1Hz in 3000m depth underwater. Potential application is demonstrated by propelling a model boat. Looking ahead, the knotted artificial muscles can empower novel biomedical devices and soft robots to explore various environments, from inside human body to the mysterious deep sea.

Hyperbranched polyester hydrogels with controlled drug release and cell adhesion properties.

Hyperbranched polyesters (HPE) have a high efficiency to encapsulate bioactive agents, including drugs, genes, and proteins, due to their globe-like nanostructure. However, the use of these highly branched polymeric systems for tissue engineering applications has not been broadly investigated. Here, we report synthesis and characterization of photocrosslinkable HPE hydrogels with sustained drug release characteristics for cellular therapies. These HPE can encapsulate hydrophobic drug molecules within the HPE cavities due to the presence of a hydrophobic inner structure that is otherwise difficult to achieve in conventional hydrogels. The functionalization of HPE with photocrosslinkable acrylate moieties renders the formation of hydrogels with a highly porous interconnected structure and mechanically tough network. The compressive modulus of HPE hydrogels was tunable by changing the crosslinking density. The feasibility of using these HPE networks for cellular therapies was investigated by evaluating cell adhesion, spreading, and proliferation on hydrogel surface. Highly crosslinked and mechanically stiff HPE hydrogels have higher cell adhesion, spreading, and proliferation compared to soft and complaint HPE hydrogels. Overall, we showed that hydrogels made from HPE could be used for biomedical applications that require spatial control of cell adhesion and controlled release of hydrophobic clues.

Ultrastrong, Thermally Stable, and Food-Safe Seaweed-Based Structural Material for Tableware.

Widely used disposable plastic tableware is usually buried or directly discharged into the natural environment after using, which poses potential threats to the natural environment and human health. To solve this problem, nondegradable plastic tableware needs to be replaced by tableware composed of biodegradable structural materials with both food safety and the excellent mechanical and thermal properties. Here, a food-safe sargassum cellulose nanofiber (SCNF) is extracted from common seaweed in an efficient and low energy consuming way under mild reaction conditions. Then, by assembling the SCNF into a dense bulk material, a strong sargassum cellulose nanofiber structural material (SCNSM) with high strength (283 MPa) and high thermal stability (>160 °C) can be prepared. The SCNSM also possesses good machinability, which can be processed into tableware with different shapes, e.g., knives and forks. The overall performance of the SCNSM-based tableware is better than commercial plastic, wood-based, and poly(lactic acid) tableware, which shows great application potential in the tableware field.

Photoswitched protein adsorption on electrostatically self-assembled azobenzene films.

Photoresponsive polymeric films fabricated by a facile electrostatic self-assembly technique are utilized to switch protein adsorption by light irradiation. The introduction of SiO(2) nanoparticles on the substrate results in a large reversible change of both wettability and protein adsorption.

Wrinkled liquid-crystalline microparticle-enhanced photoresponse of PDLC-like films by coupling with mechanical stretching.

Photoresponsive behaviors are studied in hybrid liquid-crystalline (LC) films prepared with light-responsive LC polymer microparticles as dopants using photoinert polymers as a host material. Upon mechanical stretching, both topological shape change and mesogenic alignment occur in the LC polymer microparticles, enabling the polymer-dispersed LC (PDLC)-like films to bend toward a light source upon UV irradiation. The rough morphologies of the hydrophobic LC microparticles enhance their interactions with hydrophilic polymer substrates. The bilayer-like structures of the hybrid film formed in the fabrication processes are responsible for the photomechanical behavior, which is reversibly controlled by combing light irradiation with the stretching processes.

Clinical observation of soft palate-pharyngoplasty in the treatment of obstructive sleep apnea hypopnea syndrome in children.

BACKGROUND: Childhood obstructive sleep apnea hypopnea syndrome (OSAHS) is a common clinical disease that can cause serious complications if not treated in time. The preferred treatment for OSAHS in children is surgery. AIM: To observe the effects of soft palate-pharyngoplasty on postoperative outcome, pharyngeal formation, and possible complications. METHODS: A total of 150 children with snoring, hernia, and mouth breathing were selected. A polysomnography test was performed to confirm the diagnosis of OSAHS. The children were randomly divided into experimental and control groups. The experimental group underwent adenoidectomy, tonsillectomy, and soft palate-pharyngoplasty. The control group underwent adenoidectomy and tonsillectomy. The t-test and chi-square test were used to compare conditions such as postoperative fever, postoperative hemorrhage, and pharyngeal reflux. Postoperative efficacy and complications were interrogated and observed in the form of outpatient follow-up and telephone follow-up at 6 mo and 1 year after surgery. The curative effects were divided into two groups: Cure (snoring, snoring symptoms disappeared) and non-cure. RESULTS: The effective rate of the experimental group was significantly higher than that of the control group, but the difference was not statistically significant (P > 0.05). The incidence of postoperative bleeding was lower in the experimental group. There was no postoperative pharyngeal reflux in either group. In the experimental group, the incidence of hyperthermia (body temperature exceeded 38.5 °C) was lower than that in the control group. The difference in postoperative swallowing pain scores between the experimental and control groups was significant. CONCLUSION: Soft palate-pharyngoplasty can more effectively enlarge the anteroposterior diameter and transverse diameter of the isthmus faucium. Compared with surgery alone, it can better treat OSAHS in children, improve the curative effect, reduce the risk of perioperative bleeding, close the surgical cavity, reduce the risk of postoperative infection, reduce the proportion of postoperative fever, and accelerate healing. Although this process takes more time, it is simple, safe, and effective.

Thiol/acrylate-modified PEO-PPO-PEO triblocks used as reactive and thermosensitive copolymers.

The reactive thermal-sensitive hydrogels, which combined the reversible thermosensitive and mild reactive property, were designed based on thiol-ene reaction in physiological conditions between thiol and acrylate capped thermosensitive Poloxamer 188. The modified P188A, P188SH, and their reactivity were characterized by (1)H NMR, FT-IR, GPC, DSC, Ellman method, and Rheometer. It was found that the thiol-ene reaction was pH and thermal-sensitive. There was 77.7% SH involved into the reaction at 37.0 degrees C and pH 7.4 within the first 30 min. The most of molecules reacted as CC/SH mol ratio was 1.5. The exothermic thiol-ene reaction was mild, with about DeltaH = -91.18 J/g changes. The multiblocks or network structure limited the dissolution of hydrogel, correspondingly the gel's duration and the release time of methylene blue were prolonged to 124 h. The experimental results indicated the reactive thermal-sensitive hydrogel's potential applications in drug delivery, tissue engineering, and cell encapsulation.

Characteristic comparison of bioactive scaffolds based on polyhydroxyalkoanate/bioceramic hybrids.

In this study, bioactive hybrid scaffolds were prepared by combining poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate) (PHBV) with three kinds of bioceramics, which are sol-gel bioglass (SGBG), tricalcium phosphate (TCP), and hydroxyapatite. The bioactivity and biodegradation of various scaffolds were analyzed with simulated experiments in vitro by immersing the scaffolds into simulated body fluid to evaluate their biomineralizing ability. The changes of the surface components and structures were determined by FTIR, XRD, and SEM analyses. Cell cultures and observation were made in vitro to assess the proliferation of osteoblast on these scaffolds. The results show that there might be ion exchanges and biodegradation reactions occurring between the hybrids and simulated body fluid solution, which result in the weight loss of the scaffolds and the pH changes in solution. An obvious biomineralized deposit layer was formed on the surface of the PHBV/SGBG and PHBV/TCP scaffolds, which was determined to be the bonelike crystalline hydroxyl-carbonate-apatite. The experiments on cell culture show that osteoblast could grow and proliferate on the bioactive hybrid scaffolds.

[Study on purification of total flavonoids from Rosa laevigata with macroporous resin column chromatography].

OBJECTIVE: To Study the technologic conditions of purifying total Rosa laevigata by AB-8 pocket. METHODS: Extracting flavonoids from Rosa laevigata with 70% alcohol, the thick flavonoid powder were obtained and the content of pure flavonoids in it could be determinated using spectrophotometry. Taking the adsorption of the AB-8 pocket to Rosa flavonoids as the research object, the factors that affected the AB-8 resin static absorption and desorption were studied preliminarily. RESULTS: The result showed that the effect was perfect when the flavononid concentration in the liquid was 0.3 mg/ml, the loading amount was 120 mg with the adsorption-power 1 ml/ min; And the volume of 70% alcohol was eluant 5 BV with desorption-power 1 ml/min. The pure flavonoid content in thick flavonoid powder was 25.2% and it reached 42.2% after being purified by the AB-8 pocket adsorption resin. CONCLUSION: It proved AB-8 pocket adsorption resin have a better effect on purification of the flavononids of Rosa laevigata.

Dynamic Interaction of Enterovirus 71 and Dendritic Cells in Infected Neonatal Rhesus Macaques.

Enterovirus 71 (EV71) is one of the main pathogens responsible for hand, foot, and mouth disease (HFMD). Infection with EV71 can lead to severe clinical disease via extensive infections of either the respiratory or alimentary tracts in children. Based on the previous pathological study of EV71 infections in neonatal rhesus macaques, our work using this animal model and an EV71 chimera that expresses enhanced green fluorescent protein (EGFP-EV71) primarily explored where EV71 localizes and proliferates, and the subsequent initiation of the pathological process. The chimeric EGFP-EV71 we constructed was similar to the wild-type EV71 (WT-EV71) virus in its biological characteristics. Similar clinical manifestations and histo-pathologic features were equally displayed in neonatal rhesus macaques infected with either WT-EV71 or EGFP-EV71 via the respiratory route. Fluorescent signal tracing in tissues from the animals infected with EGFP-EV71 showed that EV71 proliferated primarily in the respiratory tract epithelium and the associated lymphoid tissues. Immunofluorescence and flow cytometry analyses revealed that EV71 was able to enter a pre-conventional dendritic cell (DC) population at the infection sites. The viremia identified in the macaques infected by WT-EV71 or EGFP-EV71 was present even in the artificial presence of a specific antibody against the virus. Our results suggest that EV71 primarily proliferates in the respiratory tract epithelium followed by subsequent entry into a pre-cDC population of DCs. These cells are then hijacked by the virus and they can potentially transmit the virus from local sites to other organs through the blood circulation during the infection process. Our results suggest that the EV71 infection process in this DC population does not interfere with the induction of an independent immune response against the EV71 infection in the neonatal macaques.

Elastomeric Conducting Polyaniline Formed Through Topological Control of Molecular Templates.

A strategy for creating elastomeric conducting polyaniline networks is described. Simultaneous elastomeric mechanical properties (E < 10 MPa) and electronic conductivities (σ > 10 S cm(-1)) are achieved via molecular templating of conjugated polymer networks. Diblock copolymers with star topologies processed into self-assembled elastomeric thin films reduce the percolation threshold of polyaniline synthesized via in situ polymerization. Block copolymer templates with star topologies produce elastomeric conjugated polymer composites with Young's moduli ranging from 4 to 12 MPa, maximum elongations up to 90 ± 10%, and electrical conductivities of 30 ± 10 S cm(-1). Templated polyaniline films exhibit Young's moduli up to 3 orders of magnitude smaller compared to bulk polyaniline films while preserving comparable bulk electronic conductivity. Flexible conducting polymers have prospective applications in devices for energy storage and conversion, consumer electronics, and bioelectronics.

Approach toward nanoplate poly(styrene sulfate): synthesis of nano-polymers with special morphology by using Ldhs as template.

A simple chemical method to obtain nanopolymers with special morphology is reported. The key to the success of this preparation was the use of layered double hydroxides (LDHs), a two-dimensional host material, as template. Typical procedures include in-situ polymerization of the monomers in the interlayers of the LDH template, followed by the dissolution of LDH sheets so that the formed polymers can be free and collected. The obtained results demonstrate potential of LDHs as tools for the controlled synthesis of nanopolymers with platelike morphology.

DiGeorge syndrome associated with solitary median maxillary central incisor.

DiGeorge syndrome is a primary immunodeficiency disease characterized by dysgenesis of the thymus and parathyroid glands, conotruncal cardiac anomalies, and other dysmorphic features. Although most patients have a common microscopic deletion in chromosome 22q11.2, marked clinical variability exists. A solitary median maxillary central incisor (SMMCI) is a rare dental anomaly which may be an isolated occurrence or associated with congenital nasal airway abnormalities or holoprosencephaly. We report a patient with DiGeorge syndrome who was diagnosed at nearly 1 month of age and was later found to have a solitary median central incisor. Initially, the patient presented with recurrent episodes of respiratory distress attributed to partial airway obstruction, one of the phenotypic features of SMMCI. A fluorescence in situ hybridization study showed a chromosome 22q11.2 deletion.

Similar protective immunity induced by an inactivated enterovirus 71 (EV71) vaccine in neonatal rhesus macaques and children.

During the development of enterovirus 71 (EV71) inactivated vaccine for preventing human hand, foot and mouth diseases (HFMD) by EV71 infection, an effective animal model is presumed to be significant and necessary. Our previous study demonstrated that the vesicles in oral regions and limbs potentially associated with viremia, which are the typical manifestations of HFMD, and remarkable pathologic changes were identified in various tissues of neonatal rhesus macaque during EV71 infection. Although an immune response in terms of neutralizing antibody and T cell memory was observed in animals infected by the virus or stimulated by viral antigen, whether such a response could be considered as an indicator to justify the immune response in individuals vaccinated or infected in a pandemic needs to be investigated. Here, a comparative analysis of the neutralizing antibody response and IFN-γ-specific T cell response in vaccinated neonatal rhesus macaques and a human clinical trial with an EV71 inactivated vaccine was performed, and the results showed the identical tendency and increased level of neutralizing antibody and the IFN-γ-specific T cell response stimulated by the EV71 antigen peptide. Importantly, the clinical protective efficacy against virus infection by the elicited immune response in the immunized population compared with the placebo control and the up-modulated gene profile associated with immune activation were similar to those in infected macaques. Further safety verification of this vaccine in neonatal rhesus macaques and children confirmed the potential use of the macaque as a reliable model for the evaluation of an EV71 candidate vaccine.