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With the wind turbine become larger due to technology development, the effects of wind load on the dynamic behaviors of wind turbine system play a more important pole, especially for offshore wind turbine system with floating platform. To research such effects, the dynamic behaviors of a new semi-submersible platform of a 10 MW wind turbine in 300 m deep seawater are studied in this study. Firstly, frequency domain analysis is done to show the performances of the semi-submersible platform and prepare hydrodynamic coefficients for time domain analysis. Then time domain analysis is studied with the consideration of the coupled load effects of the wind turbine floating platform, mooring lines and ocean environment. Main load components on the wind turbine floating platform are disposed, and the effects of wind load are studied as a key point. Though the result shows that wave load still dominates the contribution to motions of rolling, heaving and surging, the contribution of wind load becomes more important than current load in the operation case, which is different of traditional floating platform.

A numerical model is developed to solve increasing ocean engineering problems involving complex and/or moving rigid structures and nonlinear free surface action with considering air movement effects. The model is based on the two-phase flow model of incompressible viscous immiscible fluids containing various interfaces, and employs a coupled immersed boundary (IB) and volume of fluid (VOF) methods. To solve the governing equations, a two-step projection method is employed and the finite difference method on a staggered and fixed Cartesian grid is used throughout the computation. The bi-conjugate gradient stabilized technique is applied to solve the pressure Poisson equation. In particular, the advection term is discretized in a composite difference scheme to enhance the stability of the algorithm. The direct forcing IB method is utilized to deal with no-slip boundary condition, while the VOF method, which employs a piecewise line interface calculation technique and a Lagrange method to reconstruct and update the interface respectively, is used to track distorted and broken free surfaces. The results of this study demonstrate the accuracy and capability of the two-phase model to simulate a moving body in free surface flows while also considering air movement effects.

This study establishes three-dimensional numerical wave tank based on the theory of viscous flow to simulate the unsteady motion response of a Wigley advancing in regular heading waves. The governing equations, Reynolds Averaged Navier-Stokes and continuity equations are discretized by finite volume method, a Reynolds-averaged NavierStokes solver is employed to predict the motions of ship, and volume of fluid method is adopted to capture the nonlinear free surface by writing user-defined functions. The outgoing waves are dissipated inside an artificial damping zone located at the rear part (about 1-2 wave lengths) of the wave tank. The numerical simulation results are compared with theoretical and experimental data from Delft University of Technology, and show good agreement with them. This research can be used to further analyze and predict hydrodynamic performance of ship and marine floating structures in waves and help to extend the applications of numerical wave tank.

For rapid modelling of ship structure and sharing of product data for a computer-integrated manufacturing system in shipbuilding, this research proposes a data exchange method between two-dimensional drawings and three-dimensional finite element models. The report of the research is followed by appropriately planning the structure of the extracted data based on the Standard for the Exchange of Product Model Data. A set of rules for two-dimensional feature recognition is established, and then the method for the extraction of graphic and non-graphic design information from two-dimensional drawings of transverse sections is presented. An algorithm for rapid modelling of the longitudinal hull structure is proposed, based on data extracted from the transverse sections. This algorithm bypasses the geometric modelling stage required in traditional manual modelling, exclusively making use of the extracted information. The proposal also enriches data exchange, greatly reduces human error in modelling and consequently improves the accuracy of the finite element modelling for the shipbuilding industry.

In this study, the local stress of unidirectional fiber reinforced marine composites under transverse direction tension is conducted by using a representative volume element (RVE). With the application of fracture mechanics theory, the strength and debonding evolution of the fibre-matrix interface is analyzed and simulated by cohesive elements in FEA. The modeling results fit the experimental results in quasi-static conditions well, which demonstrates a proper simulation method for assessing the transverse mechanical properties of marine composites. Considering the complex work environment in ocean, transverse mechanical behaviors of marine composites under different strain rates is investigated, which would provide guidance for the marine composite designers.

Some recent developments are reviewed in the use of nanoparticles as additional reinforcing phases in fibre-reinforced polymer (FRP) laminates (especially with brittle thermosetting resins) to enhance interlaminar fracture toughness and compression after impact (CAI) strength. There has been considerable interest in the past decades in using nanoparticles as secondary reinforcement, in addition to the primary reinforcing fibres in FRP laminates, in a “hybrid” approach. This is based on the clear improvement in mode I fracture toughness of nanoparticle-modified resin matrices, G IC m , with the aim of increasing interlaminar fracture toughness, G IC c and G IIC c , and further enhancing the CAI strength of FRP laminates. With addition of nanoparticles, G IC c is effectively increased; however, the transfer efficiency from G IC m to G IC c is generally similar to that for composites with conventional unmodified matrices, with G IC c / G IC m > 1 for brittle matrices but G IC c / G IC m G IC c / G IC m > 1. However, the positive correlation between G IC m and G IIC c or CAI strength is not clear. To advance research in this area, a number of fundamental and technical issues must be resolved in order to fabricate high-performance composites with hybrid reinforcements, including (1) uniform dispersion and alignment of nanoparticles, (2) optimised interface between nanoparticles and matrix; and (3) low viscosity of nanoparticle-modified matrix resins for ease of impregnation of reinforcing fibres with a high volume fraction (>60 vol%).

A series of water-swelling rubbers (WSR) were prepared by directly mixing room temperature vulcanization-2 components silicone rubber (RTV-2 SR) with superabsorbent polymer (SAP) and nanofiller (s) (halloysite nanotube or/and CaCO3). The effects of component on its mechanical behaviours and water-absorbent properties such as degree of swelling, swelling ratio, and weight loss ratio were investigated. The equilibrium swelling ratio increased with increasing amounts of water-absorbent resin. Well-dispersed nanofiller (s) increased the mechanical properties of WSR and prevented SAP breaking off from the elastomer network to effectively enhance the water-swelling durability of WSR.

An immersed boundary method is presented, which uses an approximate projection method on nonstaggered grids for computing flows with submerged and moving boundaries. The incompressible Navier–Stokes equations are discretized using a second-order accurate finite difference technique on a nonstaggered grid system, and the new immersed boundary method is proposed based on an approximate projection method with two pressure correction techniques, the Armfield method and the geometrical grid Reynolds modified method on nonstaggered grids. By using this method, the results obtained from (1) flow past a rigid cylinder in two dimensions with different Reynold numbers and (2) flow around an oscillatory circular cylinder in flow at low Keulegan–Carpenter numbers are in agreement with the reported experimental and numerical data, demonstrating that this convenient method of constraining the interface is a reliable and robust numerical approach for solving unsteady fluid flow with a submerged moving rigid object. This method has the advantage of using significantly less computation time and lower computation sources than the traditional immersed boundary methods.

In gas diffusion layers (GDLs) of proton exchange membrane fuel cells (PEMFCs), effective permeability is a key parameter to be determined and engineered. In this study, through-plane (TP) and in-plane (IP) flow behaviors of GDLs are investigated analytically based on a scaling estimate method. The TP permeability and IP permeability of unidirectional fibers are determined first, based on that the minimum distance and the inscribed radius between fibers are adopted as the characteristic lengths for normal and parallel flows, respectively. The permeabilities of two-dimensional (2D) and three-dimensional (3D) GDLs are estimated by a proper mixture of the local TP and IP permeabilities of fiber alignments. The mechanistic model agrees closely with experimental and numerical results over a wide porosity range. With the new model, the influences of porosity and fiber orientation on flow behaviors are analyzed.

Analysis of cutting force is important in research and development of metal cutting process and in designing cutting tools. This paper reports the theoretical computational formulae for cutting force for cylindrical turning using novel restricted contact tools that have inconstant tool/chip restricted contact length. These formulae are based on the minimum energy principle. The results of extensive cutting tests show that the derived theoretical computational formulae can predict the cutting force, especially the main cutting force, with reasonable accuracy. The novel RC tools-type II and type III can reduce cutting force as well as the conventional RC tools-type I. In addition, they can also effectively control the direction of chip curling, and type III RC tools may have a longer tool life due to the high strength of its cutting edge and the possibility of liquid coolant approaching the cutting zone. Finite element models have been developed to study the cutting force, and the results indicate that the main cutting force can be accurately predicted, while there are some inaccuracies for the feed force and thrust force because of the simplifications adopted during modeling.

A conductive silicone rubber (SR) composite, filled with both carbon nanotubes (CNTs) and carbon black (CB) is prepared by a simple ball milling method. Because of the good dispersion and synergistic effects of CNT and CB, the SR composite (SR with 2.5 phr CB and 1.0 phr CNT hybrid fillers) shows improvement in mechanical properties such as tensile strength and strain to failure. As well, due to the assembly of conductive pathways generated by the CNT and CB, the nanocomposite becomes highly conductive at a comparatively low concentration, with high sensitivity for tensile and compressive stress. Long-term measurement of properties shows that the SR composite maintains the excellent electrical properties under different strain histories. These outstanding properties show that the SR composite has potential applications in tensile and pressure sensors.

Transverse flow through aligned yarns with two length scales is theoretically studied. Darcy’s law and Stokes equation are employed to describe flow behaviors inside the porous yarns and in the open channels between yarns, respectively. Beavers and Joseph’s semi-empirical model and Brinkman’s extension of Darcy’s law are used to characterize the jump-velocity and continuum-stress boundary condition at the interface layer between the clear fluid and the porous yarn. The analytical model for predicting permeability is developed as a function of porosity, fiber radius, fiber cross-sectional shape, and fiber packing pattern, which would help improve the physical understandings of dual-scale flows in fibrous media. Additionally, a simple but effective semi-analytical model is provided for easy use. Permeability predictions calculated from our model agree fairly well with experimental and numerical results in literature.

This study presented experimental reports on effects of processing methods (mechanical mixing and ball milling homogenization) on the fracture toughness of as-received and phenylphosphonic acid (PPA) treated halloysite–epoxy composites. It was demonstrated that with halloysite added, the composites held higher fracture toughness value than that of neat epoxy. Large-sized particle clusters occurred during mechanical mixing process can significantly decrease by ball milling homogenization and much more uniform dispersion was obtained in the cured composites. With PPA treatment, the morphology of halloysite changed from nanotubes to nanoplatelets with a substantial increase in the total contact area between halloysite and epoxy, it further enhanced fracture toughness in PPA-treated composites. The fracture toughness mechanisms of each nanocomposite with different processing methods and chemical treatments have been illustrated.

A conductive silicone rubber (SR) composite, filled with both carbon nanotubes (CNT) and carbon black (CB) is prepared by a simple ball milling method. Because of the good dispersion and synergistic effects of CNT and CB, the SR composite shows improvement in mechanical properties. As well, due to the assembly of conductive pathways generated by the CNT and CB, the nanocomposite becomes highly conductive at a comparatively low concentration, with very high sensitivity for tensile and compressive stress. These outstanding properties show that the SR composite has potential applications in tensile and pressure sensors.

A numerical model based on the two-phase flow model for incompressible viscous fluid with a complex free surface has been developed in this study. The two-step projection method is employed to solve the Navier–Stokes equations in the numerical solutions, and finite difference method on a staggered grid is used throughout the computation. The two-order accurate volume of fluid (VOF) method is used to track the distorted and broken free surfaces. The two-phase model is first validated by simulating the dam break over a dry bed, in which the numerical results and experimental data agree well. Then 2-D fluid sloshing in a horizontally excited rectangular tank at different excitation frequencies is simulated using this two-phase model. The results of this study show that the two-phase flow model with VOF method is a potential tool for the simulation of nonlinear fluid sloshing. These studies demonstrate the capability of the two-phase model to simulate free surface flow problems with considering air movement effects.

This paper presents a novel real-time quasi-optimal trajectory generator, based on the inverse dynamics in the virtual domain (IDVD) method, to produce a reliable and efficient guidance system for autonomous underwater vehicle (AUV) docking operations. To this end, a challenging docking scenario is defined in a cluttered operating field, encompassing ocean currents and no-fly zones. Using the IDVD method, a trajectory that takes into consideration the hydrodynamic model of the vehicle is generated and the optimality of this trajectory, in regards to mission time and energy expenditure of the vehicle, is considered. Computer simulations demonstrate that the IDVD-based strategy enables the guiding of a vehicle into the dock by satisfying the final boundary conditions of the dock's position and orientation. Generated trajectories are feasible, smooth and realizable using for the vehicle's low-level auto-pilot module. In terms of computation, the solution is suitable for real-time implementation that incorporates uncertainty handling of the operating environment. For further analysis, the generated trajectory is evaluated on a high fidelity AUV simulator. The result of this latter test also demonstrates applicability of the utilized IDVD method for optimization of docking trajectories.

Jinqiong Jiang, Yiping Liu, Youhong Tang, Li Li, Ruolan Zeng, Shan Zeng, Meizuo Zhong Department of Oncology, Xiangya Hospital, Central South University, Changsha, Hunan, People’s Republic of China Abstract: Increasing evidence has shown that aldehyde dehydrogenase 1A1 (ALDH1A1), a detoxifying enzyme, is responsible for chemoresistance in a variety of tumors. Although the majority of patients with diffuse large B-cell lymphoma (DLBCL) can be cured with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP), chemoresistance is a common cause of treatment failure. This study aims to investigate the significance of ALDH1A1 expression and the mechanism by which ALDH1A1 is involved in the chemoresistance of DLBCL cells. ALDH1A1 expression was assessed in 88 DLBCL tissues by immunohistochemistry. The association between ALDH1A1 expression and outcome was evaluated. We also investigated the effect of ALDH1A1 on CHOP resistance in DLBCL cells using functional analysis. ALDH1A1 expression levels were upregulated in patients with stable or progressive disease after CHOP and its expression positively correlated with expression of STAT3 and p-STAT3. In keeping with these observations, ALDH1A1 expression was significantly associated with short survival of DLBCL patients who received CHOP chemotherapy. In functional assays in Pfeiffer cells, overexpression of ALDH1A1 conferred resistance to CHOP, while silencing of ALDH1A1 using short hairpin RNA had the opposite effect. Furthermore, we also observed that ALDH1A1 could regulate the JAK2/STAT3 pathway, while inhibition of the JAK2/STAT3 pathway by WP1066 negated the effect of ALDH1A1 overexpression. These observations reveal that ALDH1A1 induces resistance to CHOP through activation of the JAK2/STAT3 pathway in DLBCL, and its targeting provides a potential strategic approach for reversing CHOP resistance. Keywords: ALDH1A1, diffuse large B-cell lymphoma, CHOP, chemoresistance, JAK2/STAT3 pathway

Investigation of the potential use of nanofibers to reinforce composites has gained significance in many applications. In this article, the nanofiber mats of poly(acrylic acid) (PAA) and styrene–butadiene–styrene (SBS) triblock copolymer with composites structure were interweaved by double needle electrospinning process. The multiple nanofiber mats were added to conventional water-swellable rubber (WSR). Improved mechanical and physical properties of WSR were obtained. Enhancement of the swellability of WSR + PAA/SBS nanofiber mats was derived from the PAA constituent absorbing water from the surface into the bulk and introducing random internal water channels between discontinuous superabsorbent polymers. The role of SBS nanofibers in the composite of WSR + PAA/SBS nanofiber mats was more related to the mechanical properties, where the breaking force of the composite increased to twice that of the conventional WSR. Interestingly, after immersion of the WSR + PAA/SBS nanofiber mats in water for 1 week, there was only a slight decrease in their mechanical properties of less than 5% compared to the dry state. The mechanisms and effects of the nanofiber mats in enhancing the mechanical and water swelling properties of WSR are also discussed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44213.

Open Access Article. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence., A novel smart nanoparticle-based system has been developed for tracking intracellular drug delivery through surface-enhanced Raman scattering (SERS). This new drug delivery system (DDS) shows targeted cytotoxicity towards cancer cells via pH-cleavable covalent carboxylic hydrazone links and the SERS tracing capability based on gold@silica nanocarriers. Doxorubicin, as a model anticancer drug, was employed to compare SERS with conventional fluorescence tracing approaches. It is evident that SERS demonstrates higher sensitivity and resolution, revealing intracellular details, as the strengths of the original Raman signals can be amplified by SERS. Importantly, non-destructive SERS will provide the designed DDS with great autonomy and potential to study the dynamic procedures of non-fluorescent drug delivery into living cells.

In this paper, a real-time quasi-optimal trajectory planning scheme is employed to guide an autonomous underwater vehicle (AUV) safely into a funnel-shape stationary docking station. By taking advantage of the direct method of calculus of variation and inverse dynamics optimization, the proposed trajectory planner provides a computationally efficient framework for autonomous underwater docking in a 3D cluttered undersea environment. Vehicular constraints, such as constraints on AUV states and actuators; boundary conditions, including initial and final vehicle poses; and environmental constraints, for instance no-fly zones and current disturbances, are all modelled and considered in the problem formulation. The performance of the proposed planner algorithm is analyzed through simulation studies. To show the reliability and robustness of the method in dealing with uncertainty, Monte Carlo runs and statistical analysis are carried out. The results of the simulations indicate that the proposed planner is well suited for real-time implementation in a dynamic and uncertain environment.

A novel type of magnetic core-shell silica nanoparticles is developed for small interfering RNA (siRNA) delivery. These nanoparticles are fabricated by coating super-paramagnetic magnetite nanocrystal clusters with radial large-pore mesoporous silica. The amine functionalized nanoparticles have small particle sizes around 150 nm, large radial mesopores of 12 nm, large surface area of 411 m(2) g(-1) , high pore volume of 1.13 cm(3) g(-1) and magnetization of 25 emu g(-1) . Thus, these nanoparticles possess both high loading capacity of siRNA (2 wt%) and strong magnetic response under an external magnetic field. An acid-liable coating composed of tannic acid can further protect the siRNA loaded in these nanoparticles. The coating also increases the dispersion stability of the siRNA-loaded carrier and can serve as a pH-responsive releasing switch. Using the magnetic silica nanoparticles with tannic acid coating as carriers, functional siRNA has been successfully delivered into the cytoplasm of human osteosarcoma cancer cells in vitro. The delivery is significantly enhanced with the aid of the external magnetic field.

The Australian Solar Thermal Research Initiative (ASTRI) aims to develop a high optical quality heliostat with target cost – manufactured, installed and operational – of 90 AUD/m2. Three different heliostat design concepts are described, each with features identified during a prior scoping study as having the potential to contribute to cost reduction compared to the current state-of-the-art. The three concepts which are being developed will be down-selected to a single concept for testing in late 2016. The heliostat concept development work is supported by technology development streams, developing novel sandwich panel mirror facet structures, analysing and testing wind loads on heliostats in both stow and operation positions, and developing new heliostat field layouts and software tools for optical analysis of heliostats design concepts Refereed/Peer-reviewed

With the emerging nanotechnology, nanoscaled materials have drawn much attention to wide research communities for many years. Nanoscaled fibrous materials offer a multitude of fascinating features such as high surface area-to-volume ratio and tuneable porosity, making them attractive for widespread applications. Among different methods for nanofibre fabrication, electrospinning is a simple and versatile process for generating ultrathin fibres from a variety of polymeric materials or composites. This chapter gives a holistic review on current approaches and developments in electrospinning and its future trends in manufacturing advanced materials.

GF/EP composite laminates with an epoxy matrix modified by carbon black (CB) of 2.0 wt.% and copper chloride (CC) were manufactured by the vacuum assisted resin infusion (VARI) technique. The effects of CB nanoparticles and CC on improvement in Modes I and II interlaminar fracture toughness and impact damage resistance and on the electrical conductivity of GF/EP laminate composites were investigated. Delamination growth was calibrated by in situ electrical resistance changes during interlaminar fracture tests. The relationship between growth of delamination and change in electrical resistance was characterised. A damage index based on the change in electrical resistance was introduced, and a new method of electrical resistivity tomography was developed to access transverse impact damage in GF/EP laminates based on a matrix of conductive points in both in-plane and through-thickness directions. The damage images from in-plane and through-thickness electrical resistivity tomography were finally estimated with the corresponding C-scan. (c) 2012 Elsevier Ltd. All rights reserved.

A large number of laminates have been used in marine structures, such as small boat hulls, superstructures and propellers, etc. In this study, the using of composites in large scale marine hatch cover and comparison of strength, weight and cost between the conventional marine hatch cover and the composite hatch cover are investigated. The results show that the composite hatch cover is feasible and has great potential for future use because of its higher strength, lighter weight, super-corrosion resistance and economic.

A thermotropic liquid crystalline polymer (TLCP) blend with 1 wt% multiwall carbon nanotubes (MWCNTs) was prepared by melt compounding. Morphological observations of the blend show that the chemical-treated MWCNTs were well dispersed in the TLCP matrix with a good interface. MWCNTs have little effects on the thermal and rheological properties of pure TLCP. TLCP fibers with and without MWCNTs were prepared at certain drawing ratios by a melt spinning method. The degree of orientation of TLCP chains is enhanced by MWCNT micro-clusters during the fiber formation. The mechanical properties of TLCP/MWCNT fibers are significantly increased by 34.5 % for tensile strength and 38.0 % for tensile modulus in comparison with those of pristine TLCP fibers, due to the synergistic effects of MWCNT and TLCP.

Fully developed turbulent channel flow with a blade riblet surface has been simulated numerically at Reynolds number by Large Eddy Simulations (LES). The blade riblet is shown to provide a total viscous drag reduction approximately 9% with the riblet spacing and the cross section . For the sake of investigating the interaction of the turbulent flow with riblets, the mean velocity profiles, velocity fluctuations, and instantaneous flow visualization have been analyzed. It has been found that the riblet of certain size reduces drag by damping the dynamics and weakening the cross motions in the near-wall boundary layer, revealing beneficial turbulence controlling.

An experimental study was conducted to improve the electrical conductivity of continuous carbon fibre/epoxy (CF/EP) composite laminate, with simultaneous improvement in mechanical performance, by incorporating nano-scale carbon black (CB) particles and copper chloride (CC) electrolyte into the epoxy matrix. CF/EP laminates of 65 vol.% of carbon fibres were manufactured using a vacuum-assisted resin infusion (VARI) technique. The effects of CB and the synergy of CB/CC on electrical resistivity, tensile strength and elastic modulus and fracture toughness (K-IC) of the epoxy matrix were experimentally characterised, as well as the transverse tensile modulus and strength, Mode I and Mode II interlaminar fracture toughness of the CF/EP laminates. The results showed that the addition of up to 3.0 wt.% CB in the epoxy matrix, with the assistance of CC, noticeably improved the electrical conductivity of the epoxy and the CF/EP laminates, with mechanical performance also enhanced to a certain extent. (C) 2011 Elsevier Ltd. All rights reserved.

A delamination monitoring method was proposed to characterize Mode I and Mode II delamination onset in carbon fiber/epoxy (CF/EP) composite laminates through interrogation of guided waves activated and captured using piezoelectric actuators and sensors in a pitch–catch configuration. Mode I and Mode II interlaminar fracture tests were conducted using double cantilever beam (DCB) and end notch flexure (ENF) specimens to evaluate the proposed method. The changes in wave propagation velocity and wave magnitude (or attenuation), and the degree of waveform similarity between excitation and response signals, were calculated as delamination-sensitive wave parameters and plotted versus displacement recorded using a materials testing system. The kink points determined from wave parameter–displacement curves agreed well with the deviation from linearity (NL), visual observation (VIS) and maximum load (Max) points, which are often used in conventional methods for determining interlaminar fracture toughness. The propagation characteristics of the A0 wave mode in a low frequency range were demonstrated to have high sensitivity to Mode I and in particular Mode II delamination onset in CF/EP composite laminates. It was concluded that the guided waves propagating in the DCB and ENF specimens were capable of determining Mode I and Mode II interlaminar fracture toughness, complementing current practices based on visual inspection or trivial interrogation using load–displacement curve alone.

The formation of saw-tooth chip is one of the primary characteristics in high-speed cutting and in the machining of difficult-to-cut materials, such as titanium and its alloys, hardened steels. The saw-tooth chips obtained from Ti6Al4V turning were examined geometrically and metallurgically. The segment spacing, adiabatic shear band (ASB) width and the degree of segmentation were determined by micrographic observations. The microstructure evolution of ASB in terms of cutting speed was analyzed. The mechanism of saw-tooth chip formation was discussed depending on the adiabatic shear sensitivity of workpiece materials when processed at high strain and strain rates. Experimental results show that the evolution of microstructure inside the ASBs is: deformed band → deformed band + transformed band → transformed band with cutting speed increasing. As for those workpiece materials possessed high adiabatic shear sensitivity, the catastrophic instability resulting in the formation of saw-tooth chip is thermoplastic instability; as for those workpiece materials that is insensitive to shear localization, the instability in primary shear zone is periodic cracks originated at free surface ahead of tool; as for those workpiece materials in which adiabatic shear sensitivity is situated between the above two kind of materials, the interaction of thermoplastic instability and periodic cracks results in saw-tooth chip formation.

The transverse tensile properties, interlaminar shear strength (ILSS) and mode I and mode II interlaminar fracture toughness of carbon fibre/epoxy (CF/EP) laminates with 10 wt% and 20 wt% silica nanoparticles in matrix were investigated, and the influences of silica nanoparticle on those properties of CF/EP laminates were characterized. The transverse tensile properties and mode I interlaminar fracture toughness (G(IC)) increased with an increase in nanosilica concentration in the matrix resins. However, ILSS and the mode II interlaminar fracture toughness (G(IIC)) decreased with increasing nanosilica concentration, especially for the higher nanosilica concentration (20 wt%). The reduced G(IIC) value is attributed to two main competing mechanisms; one is the formation of zipper-like pattern associated with matrix microcracks aligned 45 degrees ahead of the crack tip, while the other is the shear failure of matrix. The ratio of G(IIC)/G(IC) decreased with the concentration of silica nanoparticles, comparable with similar CF/EP laminates with dispersed CNTs in matrix. Fractographic studies showed that interfacial failure between carbon fibre and epoxy resin occurred in the neat epoxy laminate, whereas a combination of interfacial failure and matrix failure occurred in the nanosilica-modified epoxy laminates, especially those with a higher nanosilica concentration (20 wt%). (C) 2011 Elsevier Ltd. All rights reserved.

In this study, an algorithm is designed specifically for automatic finite element (FE) mesh generation on the transverse structure of hulls reinforced by stiffeners. Stiffeners attached to the transverse structure are considered as line constraints in the geometry boundary. For the FE mesh generation used in this study, the line constraints are treated as boundaries and by that means the geometry domain attached to the line constraints is decomposed into sub-domains, constrained only by the closed boundaries. Then, the mesh can be generated directly on those sub-domains by the traditional approach. The performance of the proposed algorithm is evaluated and the quality of the generated mesh meets expectations.

Fluorescent liquid crystals (LCs) have wide applications in optoelectronic devices. However, the synthesis of high solid-state emission efficiency LCs is difficult. On one hand, impeding the aggregation of traditional luminogens is the prerequisite for high efficiencies; on the other hand, self-organization is an inherent attribute for LCs in the mesomorphic states. Because of such irreconcilable conflict, new strategy toward efficient fluorescent LCs is highly desirable. Herein, a conceptually new approach toward high efficiency fluorescent LCs is developed. Through rational design and combination of biphenyl-containing diazides and diynes carrying tetraphenylethylene units, soluble, regioregular, and liquid crystalline polytriazoles with high solid-state emission efficiencies (up to 63.7%) are obtained. The photophysical properties of the polymers are sensitive to their molecular structures and their solid-state quantum yields decrease with increasing spacer length. The spacer length also impacts on the...

A bioactive ceramic-reinforced liquid crystal polymer compoasite was developed as a bone replacement material. Hydroxyapatite (HA) powder was modified with polyacrylic acid (PAA) and then compounded with Vectra A950 (VA) by twin screw extrusion, finally the mixture was injection-molded to prepare the HA/VA composites with different mass ratios. TEM characterization shows that PAA modification effectively broke the HA agglomeration to primary particles. FTIR and XPS analyses indicate that PAA was successfully coated on HA powder by a bridging coordination. The loading of PAA on HA surface measured by TGA was 2.2% (by weight). Rheological study shows that PAA modification increased the physical and chemical interactions between HA powder and the polymer matrix, and hence a homogenous dispersion was obtained as revealed by SEM characterization of the fractured composite surface. Tensile tests show that PAA-modified HA/VA composite (mass ratio of 20:100) has a strength of 138 MPa, modulus of 9.3 GPa, and fracture strain of 7.2%, which match those of load-bearing bone well.

Phenylphosphonic acid (PPA) was used to unfold a unique tubular clay mineral, halloysite. By varying the durations of PPA treatment, halloysites with different levels of enfoldment and intercalation were obtained. Halloysites, particularly with the unfolded and intercalated halloysites, were effective additives in increasing the fracture toughness of the cured epoxies without sacrificing their basic properties. Fracture toughness of composites was increased with increasing intercalation levels of halloysite, with the improvement being 78.3% in KIC for the composite containing 10 wt.% of the fully PPA-intercalated and unfolded halloysite. There was a substantial increase in the contact area between halloysite and epoxy, and as a result the morphology changed from nanotubes to nano-platelets in the composites with the treated halloysites. The treated halloysites achieved a better dispersion in epoxy and promoted the formation of a large number of micro-cracks and plastic deformations in the interfaces, resulting in an improvement in fracture toughness.

Content and composition of the volatiles of Baisu and Zisu, two varieties of Perilla frutescens , obtained by SFE, HS-SPME, and hydrodistillation, were compared. A total of 64 compounds were identified by GC/MS. Perillaldehyde (21.9–58.1%) and perilla ketone (54.5–83.5%) were the main volatile components of Zisu and Baisu, respectively. They might be partly responsible for the aroma and taste of perilla . The abundance of perilla ketone indicates that it is not safe to use Baisu as vegetable, and Baisu should not be used as substitute for Zisu. SFE extracted oil with high yield, and extracted some high molecular-weight compounds that did not contribute to the aroma. The HS-SPME was simple and sensitive for the analysis of volatile compounds of fresh perilla . The results showed that the drying process influenced the volatile components of perilla .

Maleic anhydride-grafted polyethylene (MAPE) is investigated as a compatibilizer of polyethylene/organoclay nanocomposite. With MAPE help, partial exfoliation of the organoclay occurs in the nanocomposites with the melt compounding method for organoclay loading up to 8.0 wt%. Investigation of the rheological behaviors shows that at high frequencies or shear rates, the viscosity is essentially unaffected by the presence of organoclay; however, at low frequencies or shear rates, viscoelastic behavior alters dramatically, and this is attributed to the presence of anisotropic stacks of randomly oriented organoclay sheets and the formation of network structures. The important observations are firstly the initial stress overshooting observed in steady shear. At low shear rates, stress is much greater at the initial stage than the stress at the steady state; however, it can be eliminated by preshear at low shear rates, which means that preshearing can effectively break down the network structures and align the organoclay. Second, the normalized stress at the overshoot point is a function of the critical strain unit. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers

A study of a typical intercalated structure of a thermotropic liquid crystalline polymer (TLCP) with organoclay was performed to elucidate the influence of intercalated organoclay on the TLCP molecules, especially on their liquid crystallinity, thermal and rheological properties. The intercalated structures were confirmed in TLCP and organoclay formed molecular interactions with TLCP molecules in the system. Such intercalated structures caused the glass transition temperature of the nanocomposite to become invisible in thermal measurement and also caused loss of liquid crystallinity. The TLCP molecules inside the organoclay galleries showed higher thermal stability and transition temperatures, but the orderly structure of the TLCP molecules outside the galleries was destroyed by the organoclay, causing the TLCP to display lower thermal stability and transition temperatures than pristine TLCP. At 185°C, where TLCP is in the nematic phase, the nanocomposite had three orders of magnitude higher viscosity in ...

Aimed to increase the load-bearing capacity of wood-plastic composites (WPC), sisal and glass fiber fabrics were incorporated into wood—high density polyethylene (HDPE) composites by sandwiching them inside the composites during the compression molding of extruded WPC pellets. Experimental results showed that the inclusion of long fibers in less than 20 wt% in the form of fabrics, particularly glass fabrics (13—20 wt%), could effectively enhance the mechanical performance of the wood—HDPE composites with significantly increased strength and modulus as well as the improved creep resistance, compared with their unreinforced counterparts. The reinforced WPC preserved their wood-like appearances, but they have much higher strength and creep resistance. Particularly, the WPC samples reinforced by two layers of glass fabrics could have strengths that were comparable to that of solid wood in the parallel-to-grain direction but much better mechanical performance than that of wood in the perpendicular-to-grain direction. Surface treatments to the fiber fabrics using a silane coupling agent and the incorporation of maleic anhydride-grafted polyethylene into the WPC pellets during the compounding process could improve the interfacial compatibility between the reinforcing fabrics and the HDPE matrix and, thus, resulted in additional increases in the mechanical performance of the composites. On the basis of the experimental results and the simplicity of the processing methods adopted in this study, the approach, which sandwiched natural or inorganic fiber fabrics into WPC, provided a feasible method to effectively improve the load-bearing capability of WPC products, which may allow the reinforced WPC to be potentially used in certain structural applications to replace solid wood.

Photoinduced charge separation against their faster recombination is a rate determinant for photocatalytic proton reduction to hydrogen. Dissociation of electron-hole pairs into free electrons and holes in carbon nitrides greatly suffered from the inherent high recombination rate. This study has shown that coupling two energetically optimized, but with different phases carbon nitrides in the form of hybrid could significantly inhibit the charge carrier recombination and facilitate the overall charge transfer processes. It is also found that the potential gradient in this homojunction delocalizes electrons and holes, and increases the spatial charge separation. Therefore, this leads to a record high apparent quantum efficiency of 5% for photocatalytic H2 production from water under visible light irradiation in the absence of a precious metal (e.g., Pt) cocatalyst.

The influences of thermotropic liquid crystalline copolyester (TLCP) on viscosity reduction in high molecular mass polyethylene (HMMPE) filled with organoclay were investigated by controlling the blending sequence. The interactions between organoclay and TLCP in HMMPE create different morphologies and influence rheological properties of the clay/TLCP/HMMPE blends. When the organoclay was blended with TLCP first, large amounts of organoclay formed partially intercalated structures in TLCP, with phase separation occurring at the temperature when TLCP was in the nematic phase, corresponding an antagonistic effect which weakens viscosity reduction ability of TLCP for HMMPE. However, with first blending of TLCP with HMMPE and then adding organoclay into the blend, most of the organoclay enriched on TLCP surfaces in the blend. Such interaction prevents TLCP droplets from coalescing at high shear stresses, enlarging the processing window. A phenomenological model, originally for HMMPE/TLCP systems, was successfully adopted to predict the flow behaviors of clay/HMMPE/TLCP blends. POLYM. ENG. SCI., 50:1679–1688, 2010. © 2010 Society of Plastics Engineers

e19527Background: BCL6 translocations (3q27) are the most common chromosomal abnormalities in diffuse large B-cell lymphoma (DLBCL), with numerous immunoglobulin (Ig) and non-Ig genes as partners. ...

Small amounts of organoclays of different sizes and concentrations were added into thermotropic liquid crystalline polymer (TLCP) forming four types of organoclay-modified TLCPs (TC3 white, TC3 dark, TC3 FS, and TC3 UP), which had different rheological behaviors in the nematic temperature region of TLCP. Acting as viscosity reduction agents, 1.0 wt% of each organoclay-modified TLCPs were blended with high molecular mass polyethylene (HMMPE), respectively. The organoclay-modified TLCP/HMMPE blends displayed different rheological properties from each other or compared with HMMPE and 1.0 wt% TLCP/HMMPE blend [PT1]. The organoclay-modified TLCPs had greater viscosity reduction efficiency than the original TLCP in HMMPE, a lower yielding stress and yielding start shear rate, and a narrower yielding transition region than those of PT1. The rheological performance of the blends, 1.0 wt% TC3 white/HMMPE, 1.0 wt% TC3 FS/HMMPE, and PT1, could be successfully described by a binary flow pattern model.

Experimental studies on a kind of thermotropic liquid crystalline polymer (TLCP) containing 30% p-hydroxybenzoic acid (HBA), 35% hydroquinone (HQ), and 35% sebacic acid (SA) in mole fractions and its nanocomposite (TC3) containing 3.0 wt% organoclay are reported. The structures and dynamics of shear-induced phase separation and the effects of these structures on the macroscopic rheological properties of the nanocomposite are characterized under different shear conditions at 190 °C, which is in the nematic transition region of TLCP. The molecular level interactions between organoclay and TLCP molecules form a percolated-network structure in the composite, causing the composite to display complex viscosity with more than two orders of magnitude greater than that of TLCP in linear regions. However, such a network structure is easily destroyed in steady shear deformation, and it does not recover. Polarized optical microscopy (POM) equipped with a Cambridge shear system and transmission electron microscopy (TEM) confirm a shear-induced phase separation phenomenon during steady shear deformation. Two phases are observed in POM and TEM, with TLCP-rich and organoclay-rich phases. Steady shear at a small shear rate is effective to separate the two phases for characterizations.

A fully exfoliated organoclay in thermotropic liquid crystalline polymer (TLCP) based nanocomposite was prepared by a method combining ultrasonication, centrifugation, solution casting, and heat-shearing separation. Morphological study showed that the organoclays of 15–25 nm in size dispersed uniformly in TLCP with fully exfoliated structures. The organoclays formed molecular level interactions with TLCP molecules. The interactions did not affect the liquid crystallinity and mesophase structure of TLCP, but they affected the thermal stability and thermal properties of TLCP, increasing the thermal stability and shifting the transition temperatures to the higher ends. Mechanical rheology investigations in the linear viscoelastic region showed that with the exfoliated organoclay in TLCP, more obvious pseudosolidlike behavior appeared in the terminal region. The rigidity of TLCP was enhanced by the presence of the exfoliated organoclay with percolated structures in the TLCP matrix. In steady shear tests, the nanocomposite had the similar shear viscosity and N1 (the first normal stress difference) to those of TLCP in the steady state condition. Percolated structures were easily destroyed by sufficient shear strain and the exfoliated organoclays were oriented along the shear direction, even assisting the neighboring TLCP molecules to align in the flow direction, resulting in a decrease of viscosity and an increase of the N1 slope. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 712–720, 2010

Small amounts of organoclays in different sizes and concentrations were added into thermotropic liquid crystalline polymer (TLCP) by a combination method of ultrasonication, centrifugation, and solution casting (and shear-induced phase separation). Four kinds of organoclay-modified TLCP composites were obtained. TC3 UP was a kind of organoclay which displayed a marked shear-induced phase separation phenomenon at 190 °C and higher temperatures. TC3 UP could be separated into a TLCP-rich part, TC3 white, and an organoclay-rich part, TC3 dark. TC3 white was an organoclay-modified TLCP with fully exfoliated organoclay of a uniform size of 15–25 nm well dispersed in the TLCP. TC3 dark had a typical intercalated model structure with some TLCP molecules confined in organoclay galleries. TC3 FS was an organoclay-modified TLCP with organoclay of comparable size to that of the fully extended TLCP molecule, i.e., 85 nm. The organoclay layers dispersed into the polymeric matrix as a few randomly organized organoclay layers or stacks of layers in the quiescent condition in organoclay-modified TLCPs. The larger organoclay size or higher concentration of organoclay in the composites (such as, TC3 UP and TC3 dark) caused a greater proportion of the layers or stacks be hydro-dynamically impeded in the quiescent state, resulting in the filler–filler interaction becoming important and in fact dominating the long-term viscoelasticity of the composites. Additionally, the ease with which the organoclay structure could be altered by flow was considerably enhanced, primarily because of filler–filler interactions. Organoclay size has primary effect on the liquid crystallinity of TLCP. Small or comparable organoclay size with the fully extended TLCP molecule in TC3 white and TC3 FS has weak or negligible negative influence on the liquid crystallinity of TLCP, while larger organoclay size totally damages the liquid crystallinity of TLCP. The morphologies, liquid crystallinity as well as the linear and non-linear viscoelastic behaviors of organoclay-modified TLCPs have been characterized in detail.