Enhancing Dielectric Properties of (CaCu3Ti4O12 NWs-Graphene)/PVDF Ternary Oriented Composites by Hot Stretching.

Using high-dielectric inorganic ceramics as fillers can effectively increase the dielectric constant of polymer-based composites. However, a high percentage of fillers will inevitably lead to a decrease in the mechanical toughness of the composite materials. By introducing high aspect ratio copper calcium titanate (CaCu3Ti4O12) nanowires (CCTO NWs) and graphene as fillers, the ternary poly(vinylidene fluoride) (PVDF)-based composites (CCTO NWs-graphene)/PVDF with a significant one-dimensional orientation structure were prepared by hot stretching. CCTO NWs and graphene are arranged in a directional manner to form a large number of microcapacitor structures, which significantly improves the dielectric constant of the composites. When the ratio of CCTO NWs and graphene is 0.2 and 0.02, the oriented composites have the highest dielectric constant, which is 19.3% higher than the random composites, respectively. Numerical simulations reveal that the introduction of graphene and the construction of the one-dimensional oriented microstructure have a positive effect on improving the dielectric properties of the composites. This study provides a strategy to improve the dielectric properties of composite materials by structural design without changing the filler content, which has broad application prospects in the field of electronic devices.

Preparation of High-k Polymeric Composites Based on Low-k Boron Nitride Nanosheets with High-Connectivity Lamellar Structure.

Typically, the basic method to enhance the dielectric response of polymer-based composites is to fill giant dielectric ceramic fillers, such as BaTiO3 and CaCu3Ti4O12, into the polymer matrix. Here, by using low-k boron nitride (BN) with well-controlled microstructure and surface, we successfully prepared a high-k polymeric composite, where the improvement in the dielectric constant of the composite even exceeds that of composites containing BaTiO3 and CaCu3Ti4O12 particles at the same weight percent. First, a lamellar boron nitride nanosheet (BNNS) aerogel was prepared by bidirectional freezing and freeze drying, respectively, and then the aerogel was calcined at 1000 °C to obtain the lamellar BNNS skeleton with some hydroxyl groups. Finally, the epoxy resin (EP) was vacuum impregnated into the BNNS skeleton and cured inside to prepare the lamellar-structured BNNSs/EP (LBE) composites. Interestingly, the dielectric constants of LBE with a 10 wt % BNNS content reached 8.5 at 103 Hz, which was higher by 2.7 times than that of pure EP. The experimental data and the finite element simulations suggested that the increased dielectric constants of LBE resulted from the combination of two factors, namely, the lamellar microstructure and the hydroxyl groups. The stacking of the BNNS phase into a highly connected lamellar skeleton significantly increased the internal electric field and the polarization intensity, while the introduction of hydroxyl groups on the BNNS surface further improved the polarization of the composite, resulting in a significant increase in the dielectric constant of the LBE. This work provides a new strategy for improving the dielectric constant through the microstructure design of composites.

G Protein-Coupled Receptor 120 Mediates Host Defense against Clostridium perfringens Infection through Regulating NOD-like Receptor Family Pyrin Domain-Containing 3 Inflammasome Activation.

Clostridium perfringens is a major cause of infectious foodborne disease, frequently associated with the consumption of raw and undercooked food. Despite intensive studies on clarifying C. perfringens pathogenesis, the molecular mechanisms of host-pathogen interactions remain poorly understood. In soft tissue and mucosal infection models, Gpr120-/- mice, G protein-coupled receptor 120 (GPR120), are more susceptible to C. perfringens infection. Gpr120 deficiency leads to a low survival rate (30 and 10%, p < 0.01), more bacterial loads in the muscle (2.26 × 108 ± 2.08 × 108 CFUs/g, p < 0.01), duodenum (2.80 × 107 ± 1.61 × 107 CFUs/g, p < 0.01), cecum (2.50 × 108 ± 2.05 × 108 CFUs/g, p < 0.01), and MLN (1.23 × 106 ± 8.06 × 105 CFUs/g, p < 0.01), less IL-18 production in the muscle (8.54 × 103 ± 1.20 × 103 pg/g, p < 0.01), duodenum (3.34 × 103 ± 2.46 × 102 pg/g, p < 0.01), and cecum (3.81 × 103 ± 5.29 × 102 pg/g, p < 0.01), and severe organ injury. Obviously, GPR120 facilitates IL-18 production and pathogen control via potassium efflux-dependent NOD-like receptor family pyrin domain-containing 3 (NLRP3) signaling. Mechanistically, GPR120 interaction with NLRP3 potentiates the NLRP3 inflammasome assembly. Thus, this study uncovers a novel role of GPR120 in host protection and reveals that GPR120 may be a potential therapeutic target for limiting pathogen infection.

[Closed reduction and internal fixation versus transtarsal sinus small incision internal fixation for Sanders type II calcaneal fractures].

OBJECTIVE: To compare the clinical effects of closed reduction and internal fixation with limited transtarsal sinus incision in the treatment of Sanders type II calcaneal fractures. METHODS: From June 2015 to February 2018, 60 patients with Sanders type II calcaneal fractures were treated by minimally invasive method. According to the different treatment methods, they were divided into two groups: closed prying reduction and internal fixation with hollow nails(group A) and limited transtarsal sinus incision internal fixation (group B). There were 34 cases in group A, including 22 males and 12 females, aged 21 to 60(38.90±3.25) years old, 14 cases of Sanders type IIA, 14 cases of Sanders type IIB and 6 cases of Sanders type IIC. There were 20 cases in group B, including 14 males and 6 females, aged 20 to 59(39.20±2.96) years old, 8 cases of Sanders type IIA, 9 cases of Sanders type IIB and 3 cases of Sanders type IIC. Calcaneal height, calcaneal width, Gissane angle and Bohler angle were measured before and after operation. The complications, hospitalization time and cost were compared. Functional evaluation was performed by AOFAS score system one year after operation. RESULTS: Fifty-four cases were followed up for 6 to 16(11.40±2.55) months and 6 cases were lost. All the wounds healed in grade A without complications such as skin infection and necrosis. There were 1 case of nerve injury in group A, 2 cases of tendon entrapment, 2 cases of nerve injury in group B, there was no significant difference(P>0.05). There was no significant difference in calcaneal width, height, Bohlers angle and Gissane angle between group A and group B (P>0.05). There was no significant difference in AOFAS score between group A and group B(89.2±4.7 vs 88.7±4.8, P>0.05). The hospitalization expenditure and length of stay in group A were(5 021.25±1 047.19) yuan, (6.31±4.75) d, and those in group B were(13 591.35±1 975.21) yuan, (9.65±3.42) d, respectively, with significant difference(P<0.05). CONCLUSIONS: Closed reduction and internal fixation is as effective as transtarsal sinus incision reduction and internal fixation for Sanders typeIIfracture. It has the advantages of less trauma and fewer complications. Closed reduction and hollow nail fixation group can significantly shorten hospitalization time, reduce hospitalization costs, and is more economical. It is worth recommending, but attention should be paid to avoid choosing to comminute serious calcaneal fracture.

[Effect of anti-androgen and progesterone on development of regrowth antlers in 6 year old sika deer].

To investigate the effects of anti-androgen drugs and melengestrol acetate (MGA) on development of regrowth antlers in 6 year old sika deer, twenty healthysika deerwith similar body weight and antler weightwere randomly divided into five groups by using single factor test design: flutamide (n=4), bicalutamide (n=4), progesterone acetate (CPA, n=4), melengestrol acetate (MGA, n=4), control(n=4). All deer were fed with same diets and were housed outside together in an opened fence of 15 m×30 m with free access to water and feed. Treatment groups were injected subcutaneously sustained-release agents of the four drugs respectively when two-branched antlers were harvested. The control group had no special treatment. In the experiment period of 60 d, blood sampleswere collected for 4 times for each deer. The concentration of testosterone in plasma was tested and analyzed to compare the changes between different groups. Development of regrowth antlers was observed. At the end of the experiment, regrowth antlers were weighted and analyzed. The resultsshowed that the weights of regrowth antlers in treatment groups were significantly greater than those from control group and the weight gain (as compared with the control group) was 100.50%, 64.46%, 87.16% and 117.46% respectively in flutamide group, bicalutamide group, progesterone acetate group and melengestrol acetate group. For plasma testosterone concentration, it was not significantly different in the early stage (in the first 35 d), but at the end of the experimen, it was significantly higher than that of earlier stage (P<0.01) in various groups. Testosterone concentration of flutamide treated group was significantly lower than that of the other groups (P<0.01), while the level inbicalutamide and MGA treated groups was significantly higher than that in other groups (P<0.01). The results showed that both anti-androgen drugs and MGA treatment promoted the development of regrowth antlers and increased the weight of regrowth antlers, where the effect was most significant by MGA treatment. From the morphological observation of the antlers, it was found that anti-androgen and MGA treatments prolonged the growth period of regrowth antlers through delaying the ossification of antlers. However, plasma testosterone concentration was not affected by the treatments.

Vanillin Protects Dopaminergic Neurons against Inflammation-Mediated Cell Death by Inhibiting ERK1/2, P38 and the NF-κB Signaling Pathway.

Neuroinflammation plays a very important role in the pathogenesis of Parkinson's disease (PD). After activation, microglia produce pro-inflammatory mediators that damage surrounding neurons. Consequently, the inhibition of microglial activation might represent a new therapeutic approach of PD. Vanillin has been shown to protect dopaminergic neurons, but the mechanism is still unclear. Herein, we further study the underlying mechanisms in lipopolysaccharide (LPS)-induced PD models. In vivo, we firstly established rat models of PD by unilateral injection of LPS into substantia nigra (SN), and then examined the role of vanillin in motor dysfunction, microglial activation and degeneration of dopaminergic neurons. In vitro, murine microglial BV-2 cells were treated with vanillin prior to the incubation of LPS, and then the inflammatory responses and the related signaling pathways were analyzed. The in vivo results showed that vanillin markedly improved the motor dysfunction, suppressed degeneration of dopaminergic neurons and inhibited microglial over-activation induced by LPS intranigral injection. The in vitro studies demonstrated that vanillin reduces LPS-induced expression of inducible nitric oxide (iNOS), cyclooxygenase-2 (COX-2), IL-1ß, and IL-6 through regulating ERK1/2, p38 and NF-κB signaling. Collectively, these data indicated that vanillin has a role in protecting dopaminergic neurons via inhibiting inflammatory activation.

Regulated dielectric loss of polymer composites from coating carbon nanotubes with a cross-linked silsesquioxane shell through free-radical polymerization.

We report a synthetic strategy for coating multiwalled carbon nanotubes (MWCNTs) with cross-linked octa-methacrylate-polyhedral oligomeric silsesquioxane (MA-POSS) by direct, in situ free-radical polymerization in a controlled manner. This strategy resulted in a core-shell structure with an MWCNT center. The shell thickness could be varied from ∼ 7 nm to 40 nm by choosing different initiators, solvents, and weight ratios of MWCNT and octa-MA-POSS. Coated MWCNT hybrids had controlled electrical performance depending on the coating layer thickness and were well-dispersed in the polymer matrix. POSS-coated MWCNTs were compounded with poly(vinylidene fluoride) to obtain a composite with high dielectric permittivity and low dielectric loss.

Selective self-assembly of surface-functionalized fullerenes in PS-PEO on different substrates.

Polystyrene-functionalized C60 (C60-PS) was synthesized by atom-transfer radical polymerization. The structure of the hybrid was characterized by gel permeation chromatography and thermal gravimetric analysis. The self-assembly of polystyrene-block-poly(ethylene oxide) (PS-PEO)/C60-PS film in annealing solvents was studied on a silicon wafer and at the air/water interface by transmission electron microscopy. The method is an easy route to produce arrays of ordered nanostructures. The addition of C60-PS has a great effect on the self-assembly of PS-PEO. Treating the film under solvent vapor can modulate the orientation and ordering of PS-PEO microdomains. The C60-PS enhanced the formation of lamellae microstructure, and the C60-PS entered the PS phase, expanding the scale of PS domains. Nevertheless, it becomes more complex when it refers to the self-assembly at the air/water interface under solvent vapor for a long time. The selectivity of solvent to the polymer chains plays an important role as the annealing time increases.

Arthroscopically assisted ankle fusion in patients with end-stage tuberculosis.

PURPOSE: Our purpose was to evaluate the clinical outcomes of arthroscopically assisted ankle fusion in patients with end-stage tuberculosis. METHODS: Ten patients, all with end-stage tuberculosis, were operated on by arthroscopically assisted ankle fusion, and a half-ring sulcated external fixator was used. Partial weight-bearing was started on the fourth day. The clinical results were assessed with the American Orthopaedic Foot & Ankle Society score. Ankle fusion was proved by radiographs. RESULTS: At the mean follow-up of 23 months, all fusions were healed; the mean time to radiologic healing was 14.5 weeks. The final American Orthopaedic Foot & Ankle Society score was 66 points. CONCLUSIONS: Arthroscopically assisted debridement and ankle arthrodesis with an external fixator provided a very satisfactory rate of ankle fusion in 10 patients who had no recurrences or other complications. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Controlled functionalization of multiwalled carbon nanotubes with various molecular-weight poly(L-lactic acid).

Multiwalled carbon nanotubes (MWNT) were functionalized with poly(L-lactic acid) (PLLA) with different molecular weights using a "grafting to" technique. The oxidized MWNT (MWNT-COOH) were converted to the acyl-chloride-functionalized MWNT (MWNT-COCl) by treating them with thionyl chloride (SOCl2) and reacting them with PLLA to prepare the MWNT-g-PLLA. FTIR and Raman spectroscopy revealed that the PLLA was covalently attached to the MWNT, and the weight gain due to the functionalization was determined by thermogravimetric analyses (TGA). The Raman signals of the MWNT were greatly weakened as a result of the PLLA grafting. The morphology of the grafted PLLA was examined by using SEM and TEM. The amount of grafted PLLA depended on the molecular weight of the PLLA. The PLLA coated on the MWNT became thicker and more uniform with increasing PLLA molecular weight from 1000 to 3000. However, the amount of grafted PLLA became lower when the molecular weight of PLLA was further increased to 11,000 and 15,000, and the PLLA attached to the MWNT showed a squid leglike morphology forming blobs and leaving much of the MWNT surface bare.