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This paper investigates the in-plane failure mechanisms and strength of circular steel tubular Vierendeel truss arches with a rectangular section by using the finite element models. Firstly, the analytical solution for the in-plane elastic buckling load of pin-ended circular steel tubular Vierendeel truss arches with a rectangular section under a uniform radial load is obtained. Then, limiting conditions of avoiding chord local buckling before the global elastic buckling of the arch are also derived. Lastly, the in-plane instability mechanisms and failure modes of the arch under a uniform radial load, a full-span uniform vertical load (FSUVL) and a half-span uniform vertical load (HSUVL) are investigated. It is found that the arch may undergo a global failure mode or three local failure modes under FSUVL and HSUVL. Based on the theoretical and finite element results, a design equation for the global strength of arches subjected to uniform compression is proposed. Strength design equations for global failure and local failure of arches subjected to FSUVL and HSUVL are also proposed. There is a good agreement between the prediction of the proposed design equations and the FE results.

Background Extra-pair copulation behavior has been widely studied among socially monogamous birds. Many species revealed high rates of extra-pair paternity. But few of the studies have been carried out in the Asian population. Methods From 2012 to 2019, we explored the extra-pair paternity of Marsh Tits (Poecile palustris) in Xianrendong National Nature Reserve, Liaoning Province, China. During the study, adult Marsh Tits were captured with mist nets and parental birds, with nest-box traps. Blood samples were taken from the brachial vein. Parentage analyses were carried out using nine highly variable microsatellite loci through Cervus 3.0 software and maximum likelihood approach. Results Forty-nine offspring (15.08%) from 20 nests (45.45%) were the results of extra-pair fertilization out of a total of 325 offspring in 44 nests. The average extra-pair offspring ratio was 33.54%, with a set varying from 11.11 to 71.43%. Nine extra-pair fathers had been successfully identified, four of whom were the close neighbors of the focus nest while the nests of the remaining five were relatively far. No significant difference was found in the genetic similarity between the social and extra-pair mates of the female, nor in the heterozygosis among the maternal half-siblings. Conclusions In general, our study proved that the extra-pair paternity in Marsh Tits and its extra-pair mating is independent of the genetic compatibility hypothesis. This complements the understudied bird’s extra-pair paternity in Asian area and contributes to the comprehensive insight of birds’ extra-pair paternity behaviors.

Prussian blue (PB) nanoparticles are good candidates as peroxidase mimics for electrochemical biosensors due to their excellent catalytic activity and facile synthesis. However, they are rarely used in colorimetric sensing because of their aggregation in aqueous solution and intrinsic color interference. In this report, we developed a facile one-step approach to fabricate polydopamine/Prussian blue (PDA/PB) nanocomposites by anchoring highly dispersed PB nanoparticles on the surface of PDA nanospheres. As expected, the as-obtained PDA/PB nanocomposites have good dispersion in water and the intrinsic color interference is efficiently avoided. Moreover, the PDA/PB nanocomposites exhibited excellent peroxidase-like activity and could trigger the color reaction of several substrates including 3,3′,5,5′-tetramethylbenzidine (TMB), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and o-phenylenediamine (OPD) in the presence of H2O2. Based on the inhibiting effect of glutathione (GSH) on TMB oxidation, a simple colorimetric assay for the detection of GSH was proposed. This assay has a linear concentration range from 0.5 to 20 μM and a limit of detection of 0.160 μM. Taken together, this approach provides a simple, rapid, sensitive and selective method for the quantification of GSH and may shed light on the colorimetric sensing for medical diagnosis and environmental monitoring.

In this paper, a method of solving inverse kinematics based on fuzzy algorithm for hybrid system is presented. This approach could compensate the wave disturbances when the hybrid mechanism is conducting a certain task, such as, transporting the repairmen into wind turbine platform. By deriving the Jacobian matrix of the hybrid mechanism, the relationship between the angular and linear velocities of variables in joint space and gangway's end-effector in task-space can be obtained. Thereafter, the numerical integral method is used to obtain the inverse kinematic solution. Structurally, the hybrid mechanism consists of a 6-DOFs Stewart parallel platform and a 3-DOFs gangway. Due to the kinematical redundant of the hybrid boarding system, its inverse kinematic solutions are not unique. Thus, a fuzzy strategy is put forward to plan the variable values reasonably. Moreover, it can satisfy the requirement of variable constraints. When conducting ocean wave compensation, specifically, the Stewart parallel platform is used to compensate the wave disturbance in roll direction. Moreover, it is efficient to compensate other disturbances by adjusting the joint angles of gangway. The effectiveness and the robustness of the proposed method is demonstrated using numerical simulation when the wave disturbance is added into the hybrid boarding system.

The combined therapeutic strategy have aroused significant interest in cancer therapy due to its enhanced treatment efficacy and reduced side effects. This paper describes the combined chemo- and photothermal therapy of cancer based on PDA@(PDDA-ADA)3-Dox nanocomposites. Polydopamine (PDA) serves not only as photothermal agent with strong near infrared absorbance and high energy conversion efficiency, but also as a core material to carry multilayer films formed by alternatively deposition of positively charged poly(diallyldimethylammonium chloride) (PDDA) and negatively charged alginate dialdehyde (ADA) through layer-by-layer (LBL) method. Doxorubicin hydrochloride (Dox) was loaded to the PDA@(PDDA-ADA)3 nanoplatform via Schiff base bond and electrostatic interaction. The fabricated PDA@(PDDA-ADA)3-Dox nanocomposites exhibit outstanding pH-sensitive drug release, good biocompatibility and high photothermal conversion efficiency. These features make them achieve excellent anticancer therapeutic efficacy by combined chemo- and photothermal therapy. This work points that the PDA-based nanoplatform can be a universal scaffold for cancer treatment.

An azobenzene with a terminal formyl group, named as (4-[(3-Formyl-4-hydroxy)phenylazo]benzene (FHPAB)), was synthesized and used to manipulate the self-assembly of diphenylalanine (FF) molecules. Two-dimensional (2D) thin slices which are composed of ordered microspheres have been constructed through supramolecular self-assembly of FF and FHPAB. The FTIR and XPS results indicate that CN covalent bond between FF and FHPAB was generated. Hydrogen bonding and strong π-π interaction between the planar FF-HFPAB conjugates are the driving force to form the FF-HFPAB 2D thin slices. Based on the results, a possible formation mechanism of the 2D thin slices was proposed. We also found that the FF-based 2D thin slices possess superhydrophobic properties, which is therefore an extension of the range of applications of peptide assembly.

Cold-modeling gas/particle flow experiments and numerical simulations on coal combustion were performed for evaluating the furnace throat effect on the flow-field deflection and asymmetric combustion in a 600 MWe supercritical down-fired boiler. At the furnace design setting (CW = 0.529), a severely deflected gas/particle flow field appears, corresponding to a badly asymmetric combustion pattern with poor burnout and high NOx emissions. Shrinking the furnace throat from CW = 0.529 to CW = 0.500 apparently aggravates both the experimental and simulated flow-field deflection and meanwhile deteriorates asymmetric combustion. In contrast, expanding the furnace throat space to CW = 0.558 improves greatly the above problems and the flow-field symmetries are generally acceptable, accompanied by improved burnout rate and lowered NOx emissions. Findings in this work suggest that new down-fired boiler designs should be equipped with a larger furnace throat space under the circumstances with a short upper furnace aggravating the asymmetric upper furnace configuration effect.

Poly(lactic-co-glycolic acid) (PLGA) based microparticles have been widely applied in drug delivery system, but pristine PLGA particles suffers from low efficiency in release and non-targeted effect for drug delivery system. Inspired by cancer cells environment, we have fabricated an ATP-triggered delivery system based on porous PLGA microspheres covering drug-loaded ZIF-90. The system contains controlled doxorubicin releasing because ZIF-90 nanocrystals are easily collapsed under exposing to high-concentration ATP environment. In addition, ZIF-90@PLGA microparticles also perform low toxicity and 2.37 % hemolysis, and improved fluorescence intensity of doxorubicin by loading riboflavin sodium phosphate benefited from their partial Forster resonance energy transfer. This novel ATP-triggered drug delivery system based on porous PLGA particles could be widely utilized to design effective drug release biomaterials for gastric and lung cancer.

The development of peroxidase mimics can overcome shortcomings of natural peroxidases and expand their biological applications. Herein, inspired by Hemeproteins family such as peroxidase and cytochromes, polydopamine/hemin-β-cyclodextrin (PDA/Hemin-CD) supramolecular assemblies were prepared to mimick natural peroxidases using hemin as the active center. Polydopamine acts as skeleton material which could encapsulate hemin molecules during the self-assembly procedure. Mono-(6-Mercapto-6-deoxy)-β-Cyclodextrin (β-CD-SH) were decorated on the surface of PDA/Hemin serving as the molecular recognition elements. Interestingly, the addition of cholesterol could “turn off” the peroxidase activity of PDA/Hemin-CD due to the specific recognition of β-CD to cholesterol. The excellent peroxidase activity as well as molecular recognition nature of PDA/Hemin-CD make it promising candidate to construct biosensors. Based on this, a colorimetric assay for the detection of cholesterol was developed.

For the first time, we introduce a novel double-cylinder winding method for reducing the Shupe effect in interferometric fiber optic gyroscopes (IFOGs). Simulation by finite element method (FEM) is performed to calculate the dynamic temperature distribution of fiber coils, which can obtained thermal-induced rate errors in IFOGs with cross-wound coil and double cylinder-wound coil respectively. Simulation results reveal that thermal-induced rate errors in IFOGs by both winding methods can be substantially reduced under the same variable temperature conditions, but the latter has a simpler winding technology. This study is promising for reducing the temperature fragility of IFOGs.

By studying the temperature gradient and thermal stress of the difference-winding interferometric fiber optic gyroscope (IFOG) sensing coils, the improvement of the IFOG’s temperature performance is realized. A new turn-by-turn quantization thermal-induced bias error model including the traditional “pure Shupe effect”, elastic strain interactions and elasto-optical interactions are established. Compared with the traditional “pure Shupe effect” model, the experimental results show that the new model can more fully describe the thermal effect of the coils. Based on the temperature and stress distribution models mentioned above, the effects of the fiber coils with the quadrupolar (QAD) winding pattern, octupolar winding pattern and cross winding pattern on the temperature performance of IFOG are simulated under the same temperature gradient, respectively. The results show that the elastic strain and the elasto-optical effect must be considered when calculated the thermal-induced bias error of the fiber coil. Furthermore, we also come to the conclusion that cross-winding coil of the IFOG have more wonderful temperature performance than the fiber coil with quadruple winding and octupole-winding.

Morphology evolution of branched Au nanostructures (AuNSs) from Au nanoflowers to Au nanostars and finally to Au nanosnowflakes was obtained using catechol as both reducing and structure-inducing agent. These branched AuNSs were characterized by TEM and UV–vis spectroscopy and the results reveal that the increasing of number of nuclei and accelerating of growth rate after the increase of catechol concentration play an important role in the morphology evolution of branched AuNSs. The morphology of the AuNSs strongly affects their surface plasmon resonance (SPR) properties, which in turn influences their applications. The catalytic study towards p-nitrophenol suggests that the branched AuNSs with sharp tips (Au nanosnowflakes) possess the highest catalytic capacity while these with blunt tips (Au nanoflowers) have the lowest catalytic capacity. Moreover, the photothermal therapy (PTT) properties of these branched AuNSs are also shape-dependent with the highly branched Au nanosnowflakes hold the highest photothermal conversion efficiency.

Traditional underwater vehicles are limited in speed due to dramatic friction drag on the hull. Supercavitating vehicles exploit supercavitation to reduce drag and increase their underwater speed. Compared with fully wetted vehicles, the nonlinearities in the models of cavitator, fin, and particularly nonlinear planing force make the control design of supercavitating vehicles more challenging. For a widely cited benchmark model, this paper reformulates the supercavitating vehicle model in a cascade form of subsystems to facilitate the application of the backstepping control design. Based on linear matrix inequalities (LMIs), we developed a new robust H ∞ controller by introducing the sector conditions of the nonlinear characteristics of nonlinear planing force. Simulations are conducted for both initial and tracking responses to evaluate the performance and robustness of the proposed H ∞ controller for all admissible uncertainties and disturbance inputs.

To assemble metal–organic coordination complexes, a flexible dicarboxylate ligand, 2,2′-(4,6-dimethyl-5-nitro-1,3-phenylene)bis(methylene)-bis-(sulfanediyl)dibenzoic acid (H2L), has been designed and synthesized. Using the flexible ligand to assemble with copper ions, a mixture of two metal–organic complexes, Cu2(L)2(py)4·4dmso (1) and Cu2(L)2(py)6·3dmso·py (2), has been generated by solvothermal technology in one glass tube. Through increasing the mole fraction of pyridine, the pure phase of complex 2 was obtained. Both complexes have been characterized by single-crystal X-ray diffraction, elemental analysis, and thermogravimetric analysis. Complex 1 is a discrete rectangular macrocycle. The guest solvents of dimethyl sulfoxide molecules were trapped in the cavity of rectangular metallmacrocycle, resulting in the formation of an infinite supramolecular metal–organic nanotube through van der Waals interactions between the guests and the host molecules. In complex 2, the flexible ligand adopts a syn conformation to assemble with copper ions to form an infinite one-dimensional zigzag chain.

In the study of dynamical systems, the spectrum of Lyapunov exponents has been shown to be an efficient tool for analyzing periodic motions and chaos. So far, different calculating methods of Lyapunov exponents have been proposed. Recently, a new method using local mappings was given to compute the Lyapunov exponents in non-smooth dynamical systems. By the help of this method and the coordinates transformation proposed in this paper, we investigate a two-degree-of-freedom vibro-impact system with two components. For this concrete model, we construct the local mappings and the Poincare mapping which are used to describe the algorithm for calculating the spectrum of Lyapunov exponents. The spectra of Lyapunov exponents for periodic motions and chaos are computed by the presented method. Moreover, the largest Lyapunov exponents are calculated in a large parameter range for the studied system. Numerical simulations show the success of the improved method in a kind of two-degree-of-freedom vibro-impact systems.