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To investigate region-specific models for organ’s three-dimensional dose distribution prediction with neural network.

This work discusses the potential use of bottom-up synthesized graphene nanoribbons (GNRs) as nano-carriers for drug delivery systems (DDSs). GNRs have a high loading capacity for anticancer drugs due to their high specific surface area and non-covalent adsorption with hydrophobic anticancer drug molecules. Herein, we synthesized GNRs using a bottom-up approach, modified with PEG2000 (GNR-PEG) and PEG2000 carrying folic acid chains (GNR-PEG-FA), and then loaded with camptothecin (CPT). The targeting ability mediated by folic acid of the GNR derivative was evaluated using cellular assays, and the cytotoxicity of GNR systems loaded with CPT was assessed by in vitrostudies. They suggest that the functionalization of GNR derivatives with folic acid significantly affects their interaction with cells expressing different levels of folic acid receptors. The authors also explore the possibility to employ GNRs in photothermal therapy (PTT). GNR-PEG and GNR-PEG-FA display minor or no toxicity in standard cell cultures, but they show remarkable thermal response upon NIR irradiation, causing complete loss of cell viability within a few hours of treatment. This work highlights the potential of GNRs as DDSs and emphasizes the importance of further research on their biocompatibility and as a platform for PTT.

Pemphigoid diseases are a group of autoimmune disorders characterized by subepidermal blistering in the skin and mucosa. Among them, mucous membrane pemphigoid (MMP) autoantibodies are characterized by targeting multiple molecules in the hemidesmosomes, including collagen XVII (COL17/BP180), laminin-332, and integrin α6/β4. Traditionally, recombinant proteins of the autoantigens have been employed to identify circulating autoantibodies by immune assays. However, developing an efficient detection system for MMP autoantibodies has been challenging because the autoantibodies have heterogeneous profiles, and the antibody titers are typically low. Here, we introduce an ELISA that takes advantage of a native autoantigen complex rather than simple recombinant proteins. We generated HaCaT keratinocytes with a DDDDK-tag knocked in at the COL17A1locus by CRISPR/Cas9-mediated gene editing. Immunoprecipitation using the DDDDK-tag isolated a native complex that contained full-length and processed COL17 and integrin α6/β4. Then we used the complex proteins to prepare an ELISA system and enrolled 55 MMP cases to validate its diagnostic performance. The sensitivity and specificity of the ELISA for detecting MMP autoantibodies was 70.9% and 86.7%, respectively, far superior to those of conventional assays. In autoimmune diseases such as MMP, in which autoantibodies target various molecules, isolating the antigen–protein complexes can help establish a diagnostic system.

The stability of transparent conductive oxide (TCO) films of silicon thin‐film solar cells is important to the device performance. As an important TCO material, the boron‐doped zinc oxide (ZnO:B) films are grown by a low‐pressure chemical vapor deposition (LPCVD) technique. The stability of ZnO:B films with different doping levels is systematically investigated through a post‐thermal treatment at temperatures of 300 and 250 °C for different durations. In addition, the variations of optical and electrical properties of ZnO:B films after a damp‐heat treatment are studied as well. It is found that the stability of the ZnO:B films with a high doping level is better compared to lowly doped ZnO:B films. Moreover, the total transmission (TT) in the near‐infrared (NIR) wavelength range increases with increasing temperature and duration of the thermal treatment. With the increasing damp‐heat exposure duration, the TT in the NIR wavelength range slightly increases while the sheet resistance increases up to three orders of magnitude. Such observations imply a higher degradation of carrier mobility than carrier density. Further, it is found that ZnO:B films, especially those with low doping levels, show an obvious degradation in electrical properties when they are stored in normal room ambient. All these discoveries will be a great help to the practical mass production of solar modules.

Hierarchical, nanostructured nickel phosphide (h-Ni2P) spheres are synthesized by a one-pot reaction from an organic-phase mixture of nickel acetylacetonate, trioctylphosphine, tri-n-octylamine, and oleylamine (OAm). OAm is used as a surfactant to modify the surface morphology of Ni2P spheres. The h-Ni2P spheres are composed of ordered nanoparticles with 5–10 nm sizes and filled by amorphous carbon. The hierarchical structure can greatly increase the contact area between Ni2P and electrolyte, which provides more sites for Li+accommodation, shortens the diffusion length of Li+, and enhances the reactivity of the electrode reaction. Also, the amorphous carbon and the hierarchical Ni2P nanostructures can buffer volume expansion and thus increase the electrode stability during cycling. In the context of storage behavior, the h-Ni2P electrode exhibits high capacity as well as Coulombic efficiency. After 50 cycles, the reversible capacity of h-Ni2P spheres is 365.3 mA h g–1at 0.5 C and 257.8 mA h g–1at 1 C, much higher than that of Ni2P spheres (97.2 mA h g–1at 0.5 C). At a high rate of 3 C, the specific capacity of h-Ni2P is still as high as 167.1 mA h g–1.

We report a novel three-dimentional (3D) porous nano-Ni/Co(OH)2nanoflake composite film electrode for potential supercapacitor applications with both high power and energy capabilities. The 3D porous nano-Ni film with highly porous nanoramified walls functions as a scaffold to anchor Co(OH)2nanoflakes to produce a 3D nanoporous metal/hydroxide nanoflake composite electrode. Co(OH)2nanoflakes with thicknesses of 20 nm are directly electrodeposited on highly conductive 3D porous nano-Ni film prepared via a hydrogen bubble template. Impressively, the Co(OH)2nanoflake in the composite film exhibits a high specific capacitance of 1920 F g–1at 40 A g–1, with a corresponding energy density as high as 80 W h kg–1at a power density of 11 kW kg–1. Moreover, the designed composite film exhibits excellent cycling stability, making it one of the best electrode materials for high-performance supercapacitors. This work demonstrates that the 3D porous nanometal/hydroxide nanoflake composite approach is an effective strategy toward supercapacitors with high energy and power densities.

We report on electric‐field‐induced irreversible structural modifications in pentacene thin films after long‐term operation of organic field‐effect transistor (OFET) devices. Micro‐Raman spectroscopy allows for the analysis of the microstructural modifications of pentacene in the small active channel of OFET during device operation. The results suggest that the herringbone packing of pentacene molecules in a solid film is affected by an external electric field, particularly the source‐to‐drain field that parallels the a–blattice plane. The analysis of vibrational frequency and Davydov splitting in the Raman spectra reveals a singular behavior suggesting a reduced separation distance between pentacene molecules after long‐term operations and, thus, large intermolecular interactions. These results provide evidence for improved OFET performance after long‐term operation, related to the microstructures of organic semiconductors. It is known that the application of large electric fields alters the semiconductor properties of the material owing to the generation of defects and the trapping of charges. However, we first suggest that large electric fields may alter the molecular geometry and further induce structural phase transitions in the pentacene films. These results provide a basis for understanding the improved electronic properties in test devices after long‐term operations, including enhanced field‐effect mobility, improved on/off current ratio, sharp sub‐threshold swing, and a slower decay rate in the output drain current. In addition, the effects of source‐to‐drain electric field, gate electric field, current and charge carriers, and thermal annealing on the pentacene films during OFET operations are discussed.

Thickness‐dependent crystal structure, surface morphology, surface energy, and molecular structure and microstructure of a series of polycrystalline pentacene films with different film thickness ranging from several monolayers to the several hundred nanometers have been investigated using X‐ray diffraction (XRD), atomic force microscopy (AFM), contact angle meter, and Raman spectroscopy. XRD studies indicate that thin film polymorphs transformation behaviours are from the orthorhombic phase to the thin‐film phase and then to the triclinic bulk phase as measured by the increased tilt angle (θtilt) of the pentacene molecule from the c‐axis toward the a‐axis. We propose a growth model that rationalizes the θtiltincreased along with increasing film thickness in terms of grain size and surface energy varying with film growth using AFM combined with contact angle measurements. The vibrational characterizations of pentacene molecules in different thickness films were investigated by Raman spectroscopy compared to density functional theory calculations of an isolated molecule. In combination with XRD and AFM the method enables us to distinguish the molecular microstructures in different thin film polymorphs. We proposed a methodology to probe the microscopic parameters determining the carrier transport properties based on Davydov splitting and the characteristics of aromatic C–C stretching modes in Raman spectra. When compared to the triclinic bulk phase at a high thickness, we suggest that the first few monolayer structures located at the dielectric surface could have inferior carrier transport properties due to weak intermolecular interactions, large molecular relaxation energy, and more grain boundaries.

The effects of hardness ratio of coating to substrate on the scratching characteristics of four different kinds of coatings (Al, W, TiN and Ti1-xAlxN) deposited on aluminium, tungsten carbide and three types of M42 high speed steel were investigated. Based on the observed failure modes on the scratch tracks using scanning electron microscopy, coating failure maps consisting of regions of no failure, mixed failure and total coating break-through are constructed. The loading required for a particular failure mode decreases with increasing hardness ratio.

Positron annihilation lifetime (PAL) measurements have been used to study the effect of degree of branching (DB) and temperature on the atomic-scale free-volume properties and the structural transitions for hyperbranched polymer PEHO. According to the finite-term positron lifetime analysis and differential scanning calorimeter (DSC) measurements, the glass transition temperature was determined, which indicates that the higher the DB, the lower the glass transition temperature, and the higher the concentration of free-volume hole. Change in dispersion of the free volume shows that, with DB increase, there might be a disappearance of the dynamic heterogeneity in highly branched PEHO and a transition to homogeneous mass may take place. It is very interesting to observe the existence of two long-lived components (τ3 and τ4) above Tg using the continuous lifetime analysis, which suggests that two kinds of different structures appear including a local ordered region and an amorphous region due to the molecular chains motion, indicating that an effective rearrangement of chains can take place, i.e., paracrystalline regions formed above Tg related to the packing density of chains.

A series of novel hyperbranched multiarm copolyethers of PEHO-star-PPO with different molar ratios of PPO arms to PEHO cores (RA/C) were synthesized. NMR and SEC measurements confirm the molecular structure of PEHO-star-PPOs. Both glass transition temperature (Tg) and decomposition temperature (Td) of PEHO-star-PPO decrease with increasing RA/C. The self-assembly behavior of PEHO-star-PPO copolymers was investigated by TEM, SEM, DLS, etc. The results indicate that the ill-defined PEHO-star-PPO molecules could aggregate into large spherical micelles (over 100 nm) with controlled sizes, and the micelle size decreases as RA/C increases. The structure of the large micelles was explored by FT-IR, NMR, etc. Accordingly, a possible self-assembly process is put forward, and a new aggregate model termed as multimicelle aggregate (MMA) (Figure 9C) is suggested to explain the formation of the large micelles. In MMA model, the large micelles are the aggregates of small micelles associated by intermicellar interactions such as hydrogen bonds.

Abstract. Based on recent experimental observations on the formation of localization before delamination, a bifurcation-based decohesion approach is proposed in this paper to simulate the transition from localization to decohesion involved in the delamination process of compressed films. The onset and orientation of discontinuous failure are identified from the discontinuous bifurcation analysis. A discrete constitutive model is then formulated based on the bifurcation analysis to predict the evolution of material failure as decohesion or separation of continuum. The Material Point Method, that does not employ fixed mesh-connectivity, is developed as a robust spatial discretization method to accommodate the multi-scale discontinuities involved in the film delamination. To demonstrate the potential of the proposed approach, a parametric study is conducted to explore the effects of aspect ratio and failure mode on the evolution of failure patterns under different boundary conditions, which provides a better understanding on the physics behind the film delamination process.

Abstract: A periodic array of cracks in an infinite functionally graded material under mechanical and/or thermal loading is investigated. Due to non-uniform heating or cooling, compressive stresses occur causing the crack surfaces to come into contact at a certain contact length. The mixed boundary value problem is reduced to a singular integral equation with the crack contact length as an additional unknown variable. Numerical results for stress intensity factors and the crack contact length are obtained as a function of crack spacing. Effect of the material non-homogeneity on the crack tip intensity factors is discussed. Some suggestions are made for the design of thermal resistive functionally graded materials. [Copyright &y& Elsevier]

Pentacene films with submicron thickness, deposited by molecular beam deposition, were fabricated and characterized using X-ray diffraction, atomic force microscopy, and Raman spectroscopy. Organic thin-film transistors (OTFTs) were fabricated on a p-type silicon substrate, using an active layer of highly ordered small pentacene molecules grown at room temperature. Pentacene film was aligned using the photoaligned polyimide method, which is usually employed to align liquid crystals. Improved field-effect mobility, in the range 0.4−0.75 cm²/V·s, was obtained in pentacene-based OTFTs with photoaligned polyimide layers in which the pentacene molecules were aligned parallel to the direction of the transport of the carriers. The mobility was improved when the current flowed parallel or perpendicular to the orientation of the pentacene films with anisotropic ratios of 2.7−8.3. The thin-film structures of pentacene on the photoaligned polyimide surface depend on the dose of UV light that irradiates on the polyimide surface. X-ray analyses reveal that the structure of the highly ordered pentacene films includes only a single “thin-film phase”, generated by optimizing the energy of irradiation of the photoaligned polyimide. However, the poorly aligned films include two phases:  a “single-crystal phase” and a “thin-film phase”.

The influence of applied electric field on fracture toughness and cyclic electric field induced fatigue crack growth behaviour was characterized for an actuator piezoelectric ceramic under the combined loading of a high electric field and a mechanical stress. Results show that there exists a strong anisotropic effect on fracture toughness and electric field induced fatigue crack growth in polarized PZT. It is found that the apparent fracture toughness in the orientation parallel to the polarization direction is much higher than that in the transverse orientation. Under a positive electric field, increasing the electric field intensity reduces the fracture toughness in the transverse orientation but enhances that in the parallel orientation. However, the reverse is true under a negative electric field. A sphere cavity model in dielectrics was employed to characterize the effect of the external applied electric field on the evolution of cracking in an indentation. The results also show that low electric field intensity does not result in fatigue crack growth in PZT. For a relatively high applied electric field, the cracks initially grow quickly and then are arrested. This result is very significant for the long-term durability of PZT actuators.

Glass beads were modified with vinyl triethoxyl silane (VTES) followed by in situ copolymerization with styrene (St) and by direct modification with St via in situ polymerization. It was seen that the presence of glass beads did not inhibit the polymerization of St, and FT-IR spectra confirmed that the polystyrene (PS) molecules were grafted on the surfaces of glass beads. When the modified glass beads were filled in a poly(phenylene oxide) (PPO) matrix, the PS segments on the surfaces of glass beads clearly improved compatibility and enhanced interfacial adhesion between the PPO matrix and glass beads, which was responsible for the slightly increased glass transition temperature of the PPO component. Surface modifications, especially by in situ copolymerization of VTES and St, increased significantly notch impact strengths and marginal stiffness and tensile strengths of PPO/glass bead composites.

Summary A piezoelectric material layer bonded to an elastic substrate is investigated. The piezoelectric layer contains an edge crack that is perpendicular to the surface of medium. The poling axis of the piezoelectric layer is parallel to its edge. The elastic layer can be an ideal insulator or an ideal conductor. The Fourier transform technique is used to reduce the problem to a solution of singular integral equations. Both impermeable crack and permeable crack assumptions are considered. Stress and electric displacement intensity factors are investigated for different dimensions of the medium. A double-edge cracked symmetric piezoelectric laminate under symmetric electro-mechanical load is also investigated.

A series of blends of polypropylene (PP)–polyamide‐6 (PA6) with either reactive polyethylene–octene elastomer (POE) grafted with maleic anhydride (POE‐g‐MA) or with maleated PP (PP‐g‐MA) as compatibilizers were prepared. The microstructures and mechanical properties of the blends were investigated by means of tensile and impact testing and by scanning electron microscopy and transmission electron microscopy. The results indicated that the miscibility of PP–PA6 blends was improved with the addition of POE‐g‐MA and PP‐g‐MA. For the PP/PA6/POE‐g‐MA system, an elastic interfacial POE layer was formed around PA6 particles and the dispersed POE phases were also observed in the PP matrix. Its Izod impact strength was four times that of pure PP matrix, whilst the tensile strength and Young's modulus were almost unchanged. The greatest tensile strength was obtained for PP/PA6/PP‐g‐MA blend, but its Izod impact strength was reduced in comparison with the pure PP matrix.© 2002 Society of Chemical Industry

Ultra high molecular weight polyethylene (UHMWPE) crosslinked by organosilane was thermal compression molded. The organosilane used was the tri-ethyloxyl vinyl silane. Its gelation, melting behavior, crystallinity, mechanical and wear-resisting properties were systematically investigated. The results showed that the gel ratio of UHMWPE increases with the incorporation of organosilane. At a low content of organosilane, the melting point and crystallinity of the crosslinked UHMWPE increase, and hence the mechanical and wear-resisting properties are improved. However, at a high content of organosilane, these performances of the crosslinked UHMWPE become worse. At 0.4 phr silane, the wear resistance of crosslinked UHMWPE reaches its optimum value.

Summary:  The smooth contact of a rubber half-space dented by a rigid cone apex is analyzed based on the large deformation theory. The problem is treated as an axially symmetric case, and the material is assumed to be incompressible. The asymptotic equations for the domain near the apex are derived. They are solved analytically for the shrinking domain, while a numerical solution is found for the expanding domain in the vicinity of the stress singularity. The purpose of this paper is not only to solve a typical problem but also to provide an analytical method to solve a large-strain problem with a singular point.

This article discusses the methods of interface modification of composites based on raw wood flakes and high-density polyethylene (HDPE) and the effects of these modifications on composite properties. An HDPE matrix was modified by a reaction with maleic anhydride (MA) in a twin-screw extruder and then compounded with wood flakes to produce wood–polyethylene composites. Wood flakes were modified by a reaction with a silane coupling agent in an aqueous medium before being compounded with HDPE to produce silane-modified WPCs. Differential scanning calorimetry and Fourier transform infrared spectroscopy data provide evidence for the existence of a polyethylene (PE)–silane-grafted wood structure, which acts as a compatibilizer for wood flakes and PE. The results of MA-modified composites indicate that some maleated HDPE is reacting with wood through esterification to form a compatibilizer for wood flakes and HDPE. Significant improvements in tensile strength, ductility, and Izod impact strength were obtained. Scanning electron micrographs provide evidence for strong interactions between the wood flakes and the matrix agent. The results indicate that 1–2 wt % MA modification on HDPE and 1–3 wt % silane treatment on wood flakes provide WPCs with the optimum properties. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 83: 2505–2521, 2002

The structure–property relationship of wood flake–high-density polyethylene (HDPE) composites was studied in relation to the matrix agent melt flow behaviour and processing technique. The flake distribution and flake wetting were optimised to obtain acceptable mechanical properties in these composites using two processing techniques, namely twin-screw compounding and mechanical blending. The microstructure of the composites revealed that the twin-screw compounded composites based on medium melt flow index (MMFI) HDPE always achieved better flake wetting and distribution, and therefore had higher mechanical properties, than those mechanically blended composites or twin-screw compounded composites with low MFI (LMFI) HDPE. For 50:50wt% composites the overall flake wetting, depending on processing technique and matrix flow behaviour, is ranked as compounded MMFI>compounded LMFI>blended MMFI>blended LMFI. However, the uniformity of flake distribution of the composites follows a somewhat different pattern, i.e. compounded MMFI>blended MMFI>compounded LMFI>blended LMFI. Evidence shows that the medium MFI HDPE penetrates into lumens of wood fibres in wood flakes. This phenomenon combined with flake wetting and flake distribution had a profound effect on the mechanical properties, in particular the impact strength.

The fracture of films of one polypropylene (PP) homopolymer and three ethylene–propylene (EPBC) block copolymers with different ethylene content (EC) at temperatures around their glass transition (Tg) is investigated by means of the essential work of fracture (EWF) Method. The fracture behaviour is studied at low speed (2mm/min) for the different materials, in the range from −40 to +70°C. The materials are tested in the form of extruded films of 90μm thickness, in a DENT geometry, after being annealed for 1h at 120°C. The homopolymer is found to be much more temperature-sensitive than the EPBC with lower EWF values at TTg. The ductile–brittle transition of the homopolymer that occurs below its Tgis suppressed for the EPBC in the temperature range studied. The variations of the EWF fracture parameters with Tare consistent with those of a previous study in LDPE, and are explained in terms of molecular relaxation, ethylene phase content, and changes in the yield and fracture stresses. Some limitations of the EWF method are found with the more ductile materials, which show the necking phenomenon with DENT specimens at the higher temperature studied.