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Conducting polymers (CPs) with high conductivity and solution processability have made great advances since the pioneering work on doped polyacetylenesup1-3/sup, thus creating the new field of 'organic synthetic metals,sup4/sup. Various high-performance CPs have been realized, which enable the applications of several organic electronic devicessup5,6/sup. Nevertheless, most CPs exhibit hole-dominant (p-type) transport behavioursup7,8/sup, whereas the development of n-type analogues lags far behind and only a few exhibit metallic state, typically limited by low doping efficiency and ambient instability. Here we present a facilely synthesized highly conductive n-type polymer poly(benzodifurandione) (PBFDO). The reaction combines oxidative polymerization and in situ reductive n-doping, greatly increasing the doping efficiency, and a doping level of almost 0.9 charges per repeating unit can be achieved. The resultant polymer exhibits a breakthrough conductivity of more than 2,000 S cmsup-1/supwith excellent stability and an unexpected solution processability without extra side chains or surfactants. Furthermore, detailed investigations on PBFDO show coherent charge-transport properties and existence of metallic state. The benchmark performances in electrochemical transistors and thermoelectric generators are further demonstrated, thus paving the way for application of the n-type CPs in organic electronics.

Background Non-small cell lung cancer (NSCLC) is the most common lung cancer with high mortality across the world, but it is challenging to develop an effective therapy for NSCLC. Celastrol is a natural bioactive compound, which has been found to possess potential antitumor activity. However, the underlying molecular mechanisms of celastrol activity in NSCLC remain elusive. Methods Cellular function assays were performed to study the suppressive role of celastrol in human NSCLC cells (H460, PC-9, and H520) and human bronchial epithelial cells BEAS-2B. Cell apoptosis levels were analyzed by flow cytometry, Hoechst 33342, caspase-3 activity analysis, and western blot analysis. Intracellular reactive oxygen species (ROS) were analyzed by flow cytometry and fluorescence microscope. Expression levels of endoplasmic reticulum (ER) stress-related proteins and phosphorylated signal transducer and activator of transcription 3 (P-STAT3) were identified via western blot analysis. A heterograft model in nude mice was employed to evaluate the effect of celastrol in vivo. Results Celastrol suppressed the growth, proliferation, and metastasis of NSCLC cells. Celastrol significantly increased the level of intracellular ROS; thus, triggering the activation of the ER stress pathway and inhibition of the P-STAT3 pathway, and eventually leading to cell apoptosis, and the effects were reversed by the pre-treatment with N-Acetyl-l-cysteine (NAC). Celastrol also suppressed tumor growth in vivo. Conclusion The outcomes revealed that celastrol plays a potent suppressive role in NSCLC in vitro and in vivo. Celastrol induces apoptosis via causing mitochondrial ROS accumulation to suppress the STAT3 pathway. Celastrol may have potential application prospects in the therapy of NSCLC.

Background Cyclin-dependent kinase 9 (CDK9) is a promising prognostic marker and therapeutic target in cancers. Bufalin is an effective anti-tumour agent; however, the clinical application of bufalin is limited due to its high toxicity. Acetyl-bufalin, the bufalin prodrug, was designed and synthesised with higher efficiency and lower toxicity. Methods Three non-small-cell lung cancer (NSCLC) cell lines, a xenograft model and a patient-derived xenograft (PDX) model were used to examine the effects of acetyl-bufalin. CDK9/STAT3 involvement was investigated by knockdown with siRNA, proteome microarray assay, western blot analysis and co-immunoprecipitation experiments. Acute toxicity test and pharmacokinetics (PK) study were conducted to assess the safety and PK. The human NSCLC tissues were analysed to verify high CDK9 expression. Results We showed that CDK9 induced NSCLC cell proliferation and that this effect was associated with STAT3 activation, specifically an increase in STAT3 phosphorylation and transcription factor activity. Acetyl-bufalin is an effective and safety inhibitor of the CDK9/STAT3 pathway, leading to the impediment of various oncogenic processes in NSCLC. Molecular docking and high-throughput proteomics platform analysis uncovered acetyl-bufalin directly binds to CDK9. Consequently, acetyl-bufalin impaired the complex formation of CDK9 and STAT3, decreased the expressions of P-STAT3, and transcribed target genes such as cyclin B1, CDC2, MCL-1, Survivin, VEGF, BCL2, and it upregulated the expression levels of BAX and caspase-3 activity. Acetyl-bufalin inhibited tumour growth in NSCLC xenograft and PDX models. Conclusions Acetyl-bufalin is a novel blocker of the CDK9/STAT3 pathway thus may have potential in therapy of NSCLC and other cancers.

Acid fracturing is a key measure to increase production of fracture-cavity reservoirs. Affected by the fracture-cavity system, hydraulic fractures will not propagate in a plane, and the mechanism of hydraulic fracture propagation is complicated. Therefore, considering the characteristics of hydraulic fracture propagation in fracture-cavity reservoirs, we established an extended finite element (XTEM) model for hydraulic fractures in fracture-cavity reservoirs. The simulation discussed hydraulic fracture extension in cases of a single cave and a single natural fracture and revealed the mechanism of dynamic propagation and extension of hydraulic fractures. The results indicated severe stress concentrations near caves, resulting in deflections of the fracture propagation direction. In the case of a single cave, upon shifts of shafts from the central line of the cave, the conditions of penetration of the cave by hydraulic fractures were investigated. It was shown that in the case of small approaching angles, the hydraulic fractures tend to deflect and join natural fractures; also, the hydraulic fractures can deflect and join natural fractures with large approaching angles and weak cementation. Generally small approaching angles and long natural fractures tend to induce hydraulic fractures and assist propagation towards the caves, thus increasing the probability of cave penetration.

This paper describes a new two-dimensional (2-D) control volume finite element method (CV-FEM) for transient heat conduction in multilayer functionally graded materials (FGMs). To deal with the mixed-grid problem, 9-node quadrilateral grids and 6-node triangular grids are used. The unknown temperature and material properties are stored at the node. By using quadratic triangular grids and quadratic quadrilateral grids, the present method offers greater geometric flexibility and the potential for higher accuracy than the linear CV-FEM. The properties of the FGMs are described by exponential, quadratic and trigonometric grading functions. Some numerical tests are studied to demonstrate the performance of the developed method. First, the present CV-FEM with mixed high-order girds provides a higher accuracy than the linear CV-FEM based on the same grid size. Second, the material properties defined location is proved to have a significant effect on the accuracy of the numerical results. Third, the present method provides better numerical solutions than the conventional FEM for the FGMs in conjunction with course high-order grids. Finally, the present method is also capable of analysis of transient heat conduction in multilayer FGM.

Natural fractures have a significant influence on the propagation geometry of hydraulic fractures in fractured reservoirs. True triaxial volumetric fracturing experiments, in which random natural fractures are created by placing cement blocks of different dimensions in a cuboid mold and filling the mold with additional cement to create the final test specimen, were used to study the factors that influence the hydraulic fracture propagation geometry. These factors include the presence of natural fractures around the wellbore, the dimension and volumetric density of random natural fractures and the horizontal differential stress. The results show that volumetric fractures preferentially formed when natural fractures occurred around the wellbore, the natural fractures are medium to long and have a volumetric density of 6–9%, and the stress difference is less than 11 MPa. The volumetric fracture geometries are mainly major multi-branch fractures with fracture networks or major multi-branch fractures (2–4 fractures). The angles between the major fractures and the maximum horizontal in situ stress are 30°–45°, and fracture networks are located at the intersections of major multi-branch fractures. Short natural fractures rarely led to the formation of fracture networks. Thus, the interaction between hydraulic fractures and short natural fractures has little engineering significance. The conclusions are important for field applications and for gaining a deeper understanding of the formation process of volumetric fractures.

In the hydrothermal carbonization of carbohydrates, such as sucrose as raw material in this study, activated carbon microspheres were synthesized by two steps of hydrothermal carbonization (180 °C) and further heat treatment in nitrogen (1000 °C). The main purpose of this study was to investigate the effects of additives, such as H3PO4, ZnCl2, SnCl2, and CaCl2, on the surface characteristics and toluene adsorption ability by adding them into the two processes. The structural, chemical, and adsorption properties of sucrose-derived activated carbon microspheres were characterized using nitrogen adsorption, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, water contact angles, and dynamic adsorption of toluene. Results showed that additives played important roles in the synthesis process. The addition of CaCl2 in the hydrothermal process, the specific surface area of activated carbon spheres increased up to 1180 m2 g−1 compared with that of the blank sample (i.e., 724 m2 g−1). By contrast, the addition of H3PO4 in the heat treatment process increased the specific surface area to 1529 m2 g−1. Moreover, the micromorphology of activated carbon microspheres was more homogeneous when additives were added in the heat treatment process, but the activated carbon microspheres were more hydrophobic when additives were added in the hydrothermal process. These findings may help researchers to understand the influence of additives on the preparation of hydrochar-derived activated carbon.

A series of 4,4’-disubstituted-[2,2’]-bipyridines, featuring electron withdrawing/donating functional groups such as amino, chloro, nitro, ethoxycarbonyl, carboxy, methyl, methoxy and hydroxymethyl, have been synthesized and employed in the copolymerization of carbon monoxide(CO)and styrene. The available bipyridine and its derivatives were coordinated with palladium(II)acetate for catalyzing the copolymerization of CO and styrene, and the concomitant polyketone was characterized by means of 13C NMR, FTIR, differential scanning calorimetry( DSC)and element analysis techniques concerning its structure and thermal performance. The effect of different electron-donating and electron-withdrawing groups on catalyst performance and molecular weight of copolymer was studied under certain experimental condition. It has been proved that the enhancement of electron donating and conjugative effects on bipyridine ligand will not only improve the catalytic activity of the composition, but also increase the molecular weight of the as-prepared polyketone. The catalytic activity is the highest in hydroxymethyl substituted 2,2’-bipyridine ligand(1 356 gSTCO/(gPd · h)), when the molecular weight and polydispersity index of the polyketone are Mn=8 502,Mw=1 3440 and Mw/Mn=1.581, respectively.

The 150-year historical changes in concentrations of pollution elements (Pb, Cu and Zn) in sediment profiles from two riparian freshwater wetlands along the Wusuli River (boundary river between China and Russia) were studied, and the ecological risk of heavy metals and their effects on four riparian wetlands during the urban development from Khanka Lake to Black Bear Island along the Wusuli River were assessed. Results showed that there are sharp increases of the enrichment factor and the ratio of anthropogenic/total of heavy metals in the sediment profiles during the 2000s, which showed that intensive human activities during city development had greatly affected heavy metals distribution since the 1960s. According to the principal component analysis, sediment textures, redox regimes, and organic matter contents accounted for 45.7, 23.6 and 16.5 % of the total variance of element concentrations, respectively. This study also showed that ecological risk of heavy metals was increased along the Wusuli River and closely related to the water quality of the rivers as their hydrological regimes likely affect wetlands.

Cardiovascular diseases are one of the most frequent causes of death all over the world. Particularly in recent years, coronary heart diseases showed a significantly increasing trend. Nowadays artificial blood vessels have become an important implant for the treatment of a serious stenosis or occlusion of blood vessels in clinic. Synthetic polymers, such as polytetrafluoroethylene and polyurethanes, have been successfully used as large diameter artificial blood vessels, but long term patency of small artificial diameter vessels (

By utilizing fractal dimension as one of the parameters to characterize rocks, a mathematical model was derived to predict the production rate by spontaneous imbibition. This fractal production model predicts a power law relationship between spontaneous imbibition rate and time. Fractal dimension can be estimated from the fractal production model using the experimental data of spontaneous imbibition in porous media. The experimental data of recovery in gas-water-rock and oil–water–rock systems were used to test the fractal production model. The rocks (Berea sandstone, chalk, and The Geysers graywacke) in which the spontaneous water imbibition experiments were conducted had different permeabilities ranging from 0.5 to over 1000 md. The results demonstrate that the fractal production model can match the experimental data satisfactorily in the cases studied. The fractal dimension data inferred from the model match were approximately equal to the values of fractal dimension measured using a different technique (mercury-intrusion capillary pressure) in Berea sandstone.

In this paper, a scaffold, which mimics the morphology and mechanical properties of a native blood vessel is reported. The scaffold was prepared by sequential bi-layer electrospinning on a rotating mandrel-type collector. The tubular scaffolds (inner diameter 4 mm, length 3 cm) are composed of a polyurethane (PU) fibrous outer-layer and a gelatin-heparin fibrous inner-layer. They were fabricated by electrospinning technology, which enables control of the composition, structure, and mechanical properties of the scaffolds. The microstructure, fiber morphology and mechanical properties of the scaffolds were examined by means of scanning electron microscopy (SEM) and tensile tests. The PU/gelatinheparin tubular scaffolds have a porous structure. The scaffolds achieved a breaking strength (3.7±0.13 MPa) and an elongation at break (110±8%) that are appropriate for artificial blood vessels. When the scaffolds were immersed in water for 1 h, the breaking strength decreased slightly to 2.2±0.3 MPa, but the elongation at break increased to 145±21%. In platelet adhesion tests the gelatin-heparin fibrous scaffolds showed a significant suppression of platelet adhesion. Heparin was released from the scaffolds at a fairly uniform rate during the period of 2nd day to 9th day. The scaffolds are expected to mimic the complex matrix structure of native arteries, and to have good biocompatibility as an artificial blood vessel owing to the heparin release.

Polycarbonate urethane (PCU) nano-fibers were fabricated via electrospinning using N,N-dimethylformamide (DMF) and tetrahydrofuran (THF) as the mixed solvent. The effect of volume ratios of DMF and THF in the mixed solvent on the fiber structures was investigated. The results show that nano-fibers with a narrow diameter distribution and a few defects were obtained when mixed solvent with the appropriate volume ratio of DMF and THF as 1:1. When the proportion of DMF was more than 75%in the mixed solvent, it was easy to form many beaded fibers. The applied voltage in the electrospinning process has a significant influence on the morphology of fibers. When the electric voltage was set between 22 and 32 kV, the average diameters of the fibers were found between 420 and 570 nm. Scanning electron microscopy (SEM) images showed that fiber diameter and structural morphology of the electrospun PCU membranes are a function of the polymer solution concentration. When the concentration of PCU solution was 6.0 wt-%, a beaded-fiber microstructure was obtained. With increasing the concentration of PCU solutions above 6.0 wt-%, beaded fiber decreased and finally disappeared. However, when the PCU concentration was over 14.0 wt-%, the average diameter of fibers became large, closed to 2 μm, because of the high solution viscosity. The average diameter of nanofibers increased linearly with increasing the volume flow rate of the PCU solution (10.0 wt-%)when the applied voltage was 24 kV. The results show that the morphology of PCU fibers could be controlled by electrospinning parameters, such as solution concentration, electric voltage and flow rate.

Thrombus formation and blood coagulation are serious problems associated with blood contacting products, such as catheters, vascular grafts, artificial hearts, and heart valves. Recent progresses and strategies to improve the hemocompatibility of biomaterials by surface modification using photochemical immobilization and photograft polymerization are reviewed in this paper. Three approaches to modify biomaterial surfaces for improving the hemocompatibility, i.e., bioinert surfaces, immobilization of anticoagulative substances and biomimetic surfaces, are introduced. The biomimetic amphiphilic phosphorylcholine and Arg-Gly-Asp (RGD) sequence are the most effective and most often employed biomolecules and peptide sequence for improving hemocompatibility of material surfaces. The RGD sequence can enhance adhesion and growth of endothelial cells (ECs) on material surfaces and increase the retention of ECs under flow shear stress conditions. This surface modification is a promising strategy for biomaterials especially for cardiovascular grafts and functional tissue engineered blood vessels.

A novel method was used to fabricate AlN coating on graphite substrate. This approach included two steps: firstly, the emulsion composed of BN and anhydrous ethanol was sprayed on the surface of the graphite substrate; secondly, AlN coating was formed through the in-situ reaction of Al with the sprayed BN. The reaction was investigated by thermogravimetric-differential thermal analysis (TG-DTA), and the phase composition in the synthetic process was characterized by X-ray diffraction (XRD). Scanning electronic microscopy (SEM) was used to observe the morphology, and electron probe microanalysis (EPMA) was used to observe the distribution of the elements. The experimental results show that the AlN coating is dense and bonded with graphite tightly.

The alignment of carbon nanotubes (CNT) is the fundamental requirement to ensure their excellent functions but seems to be desolated in recent years. A facile method, hot-press combined with peel-off (HPPO), is introduced here, through which CNT can be successfully vertically aligned on the polymeric membrane substrate. Shear force and mechanical stretch are proposed to be the main forces to align the tubes perpendicular to the substrate surface during the peel-off process. The alignment of CNT keeps its orientation in a thin hybrid membrane by dip-coating cellulose acetate dope solution. It is expected that the stable alignment of CNT by HPPO would contribute to the realization of its potential applications.

A thermo-responsive membrane, PVDF-g-PNIPAAm, was successfully prepared from poly(vinylidene fluoride) (PVDF) membrane through surface-initiated atom transfer radical polymerization (ATRP) of a thermo-responsive monomer, N-isopropyl acrylamide (NIPAAm). The effect of the mass ratio of PVDF membrane to NIPAAm monomer on ATRP was studied in detail. The grafting copolymer was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The results showed that the NIPAAm was successfully grafted on the PVDF membrane, the membrane pores became smaller and the mass ratio 1:8 of PVDF membrane to NIPAAm was in favor of surface-initiated ATRP. The thermal stability of PVDF membrane and PVDF-g-PNIPAAm membranes was characterized by differential scanning calorimetry (DSC). Contact angles of membrane surface, water penetration and protein solution permeation were tested. Water contact angles of PVDF membrane reduced after the surface grafting of NIPAAm, which illuminated that the hydrophilicity of the grafted membrane was improved. The PVDF-g-PNIPAAm membranes exhibited good thermo-responsive permeability and antifouling property.

Polyurethanes (PU) have been widely used as biomaterial in recent years, while thrombus may still occur when contacting with blood especially for extended period of time. Poly(ethylene glycol) (PEG) and phosphorylcholine (PC)-based polymers are commonly employed for surface modification to create protein repellent surfaces. PC-based polymers have been investigated as biomimetic materials because PC is the major component in the outer layer of cell membranes. In this study, the biomimetic copolymer brush of PEG-b-poly(2-methacryloyloxyethyl phosphorylcholine) on PU surfaces was synthesized via atom transfer radical polymerization (ATRP) with a surface initiator. The flexible PEG chain was 200 g·mol-1, while the poly(2-methacryloyloxyethyl phosphorylcholine) (poly(MPC)) chain length was controlled by the ratio of monomer to sacrificial initiator in solution. The topology of the modified surfaces was characterized by the phase image of atomic force microscopy (AFM) to study the synergy effect between PEG chains and poly(MPC) chains. The unmodified and modified surfaces were characterized by Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), water contact angle and platelet adhesion. The results demonstrated that efficient grafting of PEG-b-poly(MPC) brushes on the surfaces was achieved. The PU surfaces modified with PEG and phosphorylcholine zwitterionic brushes showed effective resistance to platelet adhesion and high hemocompatibility in vitro. These PEG and PC-grafted PU materials might be potentially applied in blood-contacting materials or devices due to their good mechanical and hemocompatible properties.