Water-Tree Resistability of UV-XLPE from Hydrophilicity of Auxiliary Crosslinkers.

The water-resistant characteristics of ultraviolet crosslinked polyethylene (UV-XLPE) are investigated specially for the dependence on the hydrophilicities of auxiliary crosslinkers, which is significant to develop high-voltage insulating cable materials. As auxiliary crosslinking agents of polyethylene, triallyl isocyanurate (TAIC), trimethylolpropane trimethacrylate (TMPTMA), and N,N'-m-phenylenedimaleimide (HAV2) are individually adopted to prepared XLPE materials with the UV-initiation crosslinking technique, for the study of water-tree resistance through the accelerating aging experiments with water blade electrode. The stress-strain characteristics and dynamic viscoelastic properties of UV-XLPE are tested by the electronic tension machine and dynamic thermomechanical analyzer. Monte Carlo molecular simulation is used to calculate the interaction parameters and mixing energy of crosslinker/water binary systems to analyze the compatibility between water and crosslinker molecules. Water-tree experiments verify that XLPE-TAIC represents the highest ability to inhibit the growth of water-trees, while XLPE-HAV2 shows the lowest resistance to water-trees. The stress-strain and viscoelastic properties show that the concentration of molecular chains connecting the adjacent lamellae in amorphous phase of XLPE-HAV2 is significantly higher than that of XLPE-TAIC and XLPE-TMPTMA. The molecular simulation results demonstrate that TAIC/water and TMPTMA/water binary systems possess a higher hydrophilicity than that of HAV2/water, as manifested by their lower interaction parameters and mixing free energies. The auxiliary crosslinkers can not only increase the molecular density of amorphous polyethylene between lamellae to inhibit water-tree growth, but also prevent water molecules at insulation defects from agglomerating into micro-water beads by increasing the hydrophilicity of auxiliary crosslinkers, which will evidently reduce the damage of micro-water beads on the amorphous phase in UV-XLPE. The better compatibility of TAIC and water molecules is the dominant reason accounting for the excellent water resistance of XLPE-TAIC.

Improved Water-Tree Resistances of SEBS/PP Semi-Crystalline Composites under Crystallization Modifications.

Water-tree resistances of styrene block copolymer/polypropylene (SEBS/PP) composites are investigated by characterizing crystallization structures in correlation with the dynamic mechanical properties to elucidate the micro-structure mechanism of improving insulation performances, in which the accelerated aging experiments of water trees are performed with water-knife electrodes. The water-tree morphology in spherulites, melt-crystallization characteristics and lamella structures of the composite materials are observed and analyzed by polarizing microscopy (PLM), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), respectively. Dynamic relaxation and stress-strain characteristics are specifically studied by means of a dynamic thermomechanical analyzer (DMA) and electronic tension machine, respectively. No water-tree aging occurs in both the highly crystalline PP and the noncrystalline SEBS elastomer, while the water trees arising in SEBS/PP composites still has a significantly lower size than that in low-density polyethylene (LDPE). Compared with LDPE, the PP matrix of the SEBS/PP composite represent a higher crystallinity with a larger crystallization size in consistence with its higher mechanical strength and lower dynamic relaxation loss. SEBS molecules agglomerate as a "island" phase, and PP molecules crystallize into thin and short lamellae in composites, leading to the blurred spherulite boundary and the appreciable slips between lamellae under external force. The high crystallinity of the PP matrix and the strong resistance to slips between lamellae in the SEBS/PP composite essentially account for the remarkable inhibition on water-tree growth.

Taurine-induced fabrication of nano-architectured conducting polypyrrole on biomedical titanium.

In this article, taurine, one of the small biomolecules associated with bone metabolism, is firstly utilized to induce the fabrication of nano-architectured conducting polypyrrole (NCPPy) on biomedical titanium in diverse pH values of phosphate buffer solution (PBS). Accordingly, the possible mechanism for the fabrication of NCPPy is proposed, which is dependent on the states of polytaurine from the polymerization of taurine, i.e., the inability of forming polytaurine and unordered restricted space results in taurine-incorporated and polytaurine-incorporated tightly packed nanoparticles (pH 6.2 and 8.0), respectively, and however, ordered restricted space constructed by polytaurine chains induces the fabrication of polytaurine-incorporated nanopillars (pH 6.8) and polytaurine-incorporated nanowire networks (pH 7.4).

Reversibly controlling preferential protein adsorption on bone implants by using an applied weak potential as a switch.

A facile method is needed to control the protein adsorption onto biomaterials, such as, bone implants. Herein we doped taurocholic acid (TCA), an amphiphilic biomolecule, into an array of 1D nano-architectured polypyrrole (NAPPy) on the implants. Doping TCA enabled the implant surface to show reversible wettability between 152° (superhydrophobic, switch-on state) and 55° (hydrophilic, switch-off state) in response to periodically switching two weak electrical potentials (+0.50 and -0.80 V as a switch-on and switch-off potential, respectively). The potential-switchable reversible wettability, arising from the potential-tunable orientation of the hydrophobic and hydrophilic face of TCA, led to potential-switchable preferential adsorption of proteins as well as cell adhesion and spreading. This potential-switchable strategy may open up a new avenue to control the biological activities on the implant surface.

Nanostructured conducting polymers as intelligent implant surface: fabricated on biomedical titanium with a potential-induced reversible switch in wettability.

Conducting polypyrrole (PPy) nanotube arrays, nanotube networks and irregular films are deposited on biomedical titanium. By in situ application of weak periodic potentials, the nanostructured conducting polymers undergo a reversible switch in wettability, which is a redox process of dopant molecules (as hydrophilic groups) immobilized and de-immobilized on the surface of the conducting polymers.

Effects of triclosan exposure on stem cells from human exfoliated deciduous teeth (SHED) fate.

Triclosan (TCS), a widely used broad-spectrum antibacterial agent and preservative, is commonly found in products and environments. Widespread human exposure to TCS has drawn increasing attention from researchers concerning its toxicological effect. However, minimal studies have focused on the impact of TCS exposure on human stem cells. Therefore, the aim of the present study was to evaluate the effects of TCS exposure on stem cells from human exfoliated deciduous teeth (SHED) and its molecular mechanisms. A series of experimental methods were conducted to assess cell viability, morphology, proliferation, differentiation, senescence, apoptosis, mitochondrial function, and oxidative stress after SHED exposure to TCS. Furthermore, transcriptome analysis was applied to investigate the response of SHED to different concentrations of TCS exposure and to explore the molecular mechanisms. We demonstrated that TCS has a dose-dependent proliferation and differentiation inhibition of SHED, while promoting cellular senescence, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and oxidative stress, as well as significantly induces apoptosis and autophagy flux inhibition at high concentrations. Interestingly, no significant morphological changes in SHED were observed after TCS exposure. Transcriptome analysis of normal and TCS-induced SHED suggested that SHED may use different strategies to counteract stress from different concentrations of TCS and showed significant differences. We discovered that TCS mediates cellular injury of SHED by enhancing the expression of PTEN, thereby inhibiting the phosphorylation levels of PI3K and AKT as well as mTOR expression. Collectively, our findings provide a new understanding of the toxic effects of TCS on human stem cell fate, which is important for determining the risk posed by TCS to human health.

Wireless Electrochemotherapy by Selenium-Doped Piezoelectric Biomaterials to Enhance Cancer Cell Apoptosis.

Cancer residues around the surgical site remain a significant cause of treatment failure with cancer recurrence. To prevent cancer recurrence and simultaneously repair surgery-caused defects, it is urgent to develop implantable biomaterials with anticancer ability and good biological activity. In this work, a functionalized implant is successfully fabricated by doping the effective anticancer element selenium (Se) into the potassium-sodium niobate piezoceramic, which realizes the wireless combination of electrotherapy and chemotherapy. Herein, we demonstrate that the Se-doped piezoelectric implant can cause mitochondrial damage by increasing intracellular reactive oxygen species levels and then trigger the caspase-3 pathway to significantly promote apoptosis of osteosarcoma cells in vitro. Meanwhile, its good biocompatibility has been verified. These results are of great importance for future deployment of wireless electro- and chemostimulation to modulate biological process around the defective tissue.

The antibacterial effect of potassium-sodium niobate ceramics based on controlling piezoelectric properties.

The implant infection is one of the most serious postsurgical complications of medical device implantation. Therefore, the development of biocompatible materials with improved antibacterial properties is of great importance. It might be a new insight to apply the intrinsic electrical properties of biomaterials to solve this problem. Here, potassium-sodium niobate piezoceramics (K0.5Na0.5NbO3, KNN) with different piezoelectric constants were prepared, and the microstructures and piezoelectric properties of these piezoceramics were evaluated. Moreover, the antibacterial effect and biocompatibility of these piezoceramics were assayed. Results showed that these piezoceramics were able to decrease the colonies of bacteria staphylococcus aureus (S. aureus), favor the rat bone marrow mesenchymal stem cells (rBMSCs) proliferation and promote the cell adhesion and spreading. The above effects were found closely related to the surface positive charges of the piezoceramics, and the sample bearing the most positive charges on its surface (sample 80KNN) had the best performance in both antibacterial effect and biocompatibility. Based on our work, it is feasible to develop biocompatible antibacterial materials by controlling piezoelectric properties.

A spatially varying charge model for regulating site-selective protein adsorption and cell behaviors.

Implanted materials that enter the body first interact with proteins in body fluids, and cells then perceive and respond to the foreign implant through this layer of adsorbed proteins. Thus, spatially specific regulation of protein adsorption on an implant surface is pivotal for mediating subsequent cellular behaviors. Unlike the surface modulation strategy for traditional biomaterials, in this research, materials with a nonuniform spatial distribution of surface charges were designed to achieve site-selective protein adsorption and further influence cell behavior by charge regulation. Spatially varying microdomains with different levels of piezoelectricity were generated via a focus laser beam-induced phase transition. In addition, after polarization, the zones with different levels of piezoelectricity showed significant differences in surface charge density. The results of scanning Kelvin probe force microscopy (SKPM) showed that the surface charge on the material exhibits a nonuniform spatial distribution after laser irradiation and polarization. Site-specific charge-mediated selective protein adsorption was demonstrated through a protein adsorption experiment. Cell behavior analysis showed that the increase in charge density was conducive to promoting cell adhesion and the formation of filopodia while the nonuniform spatial distribution of charge promoted an oriented arrangement of cells; both features accelerated cell migration. This study provides a new method for spatially regulating protein adsorption through surface charges to further influence cell behaviors.

Elastomeric conductive hybrid hydrogels with continuous conductive networks.

Elastomeric conductive hybrid hydrogels (ECHs) combining conducting polymers with elastomeric hydrogels have recently attracted interest due to their wide range of applications in bioelectronics such as wearable or implantable sensing devices. However, the conductivity of ECHs is typically compromised when conductive polymers are used as fillers in hydrogel networks because the inherent limitations of ECHs severely restrict their applicability. Here, we significantly improved the electrical conductivity of ECHs by using a bioinspired catechol derivative, dopamine (DA), as the dopant and mediator for the in situ polymerization of conducting polypyrrole (PPy) within the elastomeric hydrogel dual-networks. In general, ECHs prepared by conventional methods tend to form separate island structures of conductive polymers dispersed within porous hydrogel matrices. We found that a continuous conductive PPy network prepared using the DA mediator facilitated fast electron transfer within the ECHs, which showed good elastomeric mechanical properties, excellent biocompatibility and high force- or strain-responsiveness suitable for implantable strain-sensing applications.

Chondroitin sulphate-guided construction of polypyrrole nanoarchitectures.

Nanospheres, nanocones, and nanowires are three typical polypyrrole (PPy) nanoarchitectures and electrochemically polymerized with the dope of chondroitin sulphate (CS) in this study. CS, a functional biomacromolecule, guides the formation of PPy nanoarchitectures as the dopant and morphology-directing agent. Combined with our previous reported other PPy nanoarchitectures (such as nanotube arrays and nanowires), this work further proposed the novel mechanism of the construction of PPy/CS nanoarchitectures with the synergistic effect of CS molecular chains structure and the steric hindrance. Compared to the undoped PPy, MC3T3-E1 cells with PPy/CS nanoarchitectures possessed stronger proliferation and osteogenic differentiation capability. This suggests that PPy/CS nanoarchitectures have appropriate biocompatibility. Altogether, the nanoarchitectured PPy/CS may find application in the regeneration of bone defect.

[Global improvement in agitated depression treated with the alliance therapy of acupuncture and seroxat and the observation of the quality of life].

OBJECTIVE: To compare the differences in the efficacy on agitated depression among the alliance therapy of acupuncture and seroxat, the alliance therapy of electroacupuncture and seroxat and the simple application of seroxat. METHODS: One hundred and two cases were randomized into a medication group, a conventional acupuncture + medication group and an electroacupuncture + medication group, 34 cases in each one. In the medication group, seroxat was prescribed for oral administration, once per day. In the conventional acupuncture + medication group, seroxat was applied in combination with the conventional acupuncture therapy, in which, Baihui (GV 20) and Yintang (EX-HN 3) were taken as the main acupoints. In the electroacupuncture + medication group, seroxat was applied in combination with electroacupuncture, in which, on the basic therapeutic program as the conventional acupuncture + medication group, the electric stimulation was attached to Baihui (GV 20) and Yintang (EX-HN 3). Acupuncture was applied once every two days, the treatment of 6 weeks made one session and one session treatment was required in the research. Before and after treatment, the clinical global impression (CGI) and the World Health Organization Quality of Life-BREF (WHOQOL-BREF) were adopted for the assessment in each group. RESULTS: (1) CGI comparison: the severity of illness (SI) after treatment was all alleviated significantly for the patients in three groups as compared with that before treatment (all P < 0.001), but the difference was not significant statistically among groups (P > 0.05). The global improvement (GI) was different significantly among three groups (P < 0.05), in which GI in the electroacupuncture + medication group was the best, that in the conventional acupuncture + medication group was taken second place. The total improvement rates were 100.0% (29/29), 96.9% (31/32) and 93.5% (29/31) separately. The difference in the efficacy index (EI) was not significant statistically among three groups (P > 0.05). Concerning to the adverse events, there were 1 case (mild insomnia) in the medication group, 1 case (moderate anorexia) in the conventional acupuncture + medication group and 2 cases (mild insomnia and dry mouth) in the electroacupuncture + medication group. (2) WHOQOL-BREF comparison: compared with those before treatment, all the indices in the electroacupuncture + medication group were increased significantly after treatment (all P < 0.01); except the indices in the physiological field, all the other indices were improved in the conventional acupuncture + medication group after treatment (P < 0.01, P < 0.05); the scores only in the physiological field and social field were higher significantly than those before treatment in the medication group (P < 0.01, P < 0.05). After treatment, the statistically significant difference was displayed only in the psychological field among three groups (P < 0.05), in which, the improvement in the electroacupuncture + medication group was the best, that in the conventional acupuncture + medication group was taken second place and that in the medication group was the worst. CONCLUSION: Either the alliance therapy of acupuncture and medication or the simple oral administration of seroxat improves the overall efficacy and the quality of life in the patients with agitated depression. The efficacy of the alliance therapy of acupuncture and medication is superior to the simple oral administration of seroxat and the efficacy of electroacupuncture is superior to the conventional acupuncture therapy.

[Professor OUYANG Qun's clinical experience on application of single point].

The clinical experience of Professor OUYANG Qun in using single acupoint includes treatment of Meniere's syndrome with Baihui (GV 20), optic neuritis with "Fengyan" (Extra point), painful heel with Xiaguan (ST 7), lymphoid tuberculosis with Quchi (LI 11), acute sore throat with Kongzui (LU 6), painful diseases with "Luolingwu" (Extra point), chest distress with "Kuanxiong" (Extra point), hordeolum with Feishu (BL 13), headache in menstrual period with Xuehai (SP 10), frozen shoulder with Tiaokou (ST 38), toothache with Waihuaijian (Extra point), occipital pain with Chengshan (BL 57) and vomiting with Yongquan (KI 1).