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Dynamic response of open-cell metal foam under low-velocity impact loading is important in applications involving impact resistance and energy absorption, etc. Assuming that metal foam is a conceptually continuous material, the macroscopic mechanical behaviors, both static and dynamic, must be studied. Within the dynamic mechanical properties of metal foam, impact response becomes the renewed interest to understand the characteristics of impact deformation. The present work aims to experimentally and numerically analyze the low-velocity impact response of open-cell metal foam. A series of low-velocity drop impact tests are realized on the open-cell metal foam samples with different relative densities and at different impact velocity. Afterwards, a well compiled program in Python controls the whole multiple drop impact process on each sample of metal foam. Corresponding numerical modeling and the simulation for single impact analysis are continuously carried out with the finite element (FE) program ABAQUS/Explicit. Proper meshing technique, loading and boundary conditions are conducted on all the foam models, and at the same time, the required mechanical properties: elastic module, Poisson's ratio, uniaxial stress-strain response and strain-rate dependence are utilized. In conclusion, the simulated results provide the good agreements with the experimental results in the case of low-velocity impact testing of open-cell metal foam. Experimental procedure and numerical simulation offer good approaches to improve the impact resistance and energy absorption of the open-cell metal foam.

The weathering of hemp fiber influences their appearance and mechanical properties. The aim of this study is to better understand the mechanism of aging of hemp fiber exposed to different conditions (moisture, heat and UV aging). A xenon aging test machine was used to simulate and accelerate the natural ageing. The influence of each aging condition on the mechanical properties of hemp fiber is investigated by micro tensile tests. The microstructures and water absorption of these natural fibers were analyzed by means of SEM and gravimetric methods. Humidity absorption of hemp fibers depends on the relative humidity, not concerning the temperature. Temperature accelerates the saturation of fibers. All aging process reduced the mechanical properties of hemp fibers. After 4 weeks exposure, fibers aged by UV has the worst mechanical properties compared to humidity and temperature aging.

The purpose of this study is to present a simplified analytical method to estimate ground lateral displacement due to excavation. Excavations of foundation pit will inevitably lead to soil movements that may adversely impact surrounding facilities or structures. Thus, estimation of the ground displacement induced by excavation is essential in engineering practice.

Based on a theory of elastic mechanics, a simplified analytical method for predicting the ground lateral displacement resulting from foundation pit excavation is proposed.

As the distance from the soil to the supporting structure increases, the maximum ground lateral displacement decreases nonlinearly but at a reduced rate. Poisson’s ratio of soil has a mild influence on the ground lateral displacement, whereas the influence of the supporting structure’s deflection modes is significant.

The advantage of the proposed simplified analytical method lies in that it considers the supporting structure’s arbitrary deflections, giving it wider practical applicability than previous methods.

The purpose of this paper is to improve the generation efficiency of singlet oxygen of methylene blue molecules through finely controlling their aggregation states in drug carriers.

As a photosensitiser in photodynamic therapy, methylene blue (MB) was loaded on citrate-modified hydroxyapatite (HAp) through an electrostatic interaction and followed by encapsulation of coordination complexes of tannic acid (TA) and Fe(III) ions. Ultraviolet-visible absorption spectrum of the supernatant after incubation of samples was recorded at certain time interval to investigate the release behaviour of MB. Photodynamic activity of MB was determined by the oxidation reaction of uric acid by singlet oxygen generated by MB under illumination.

Almost all MB molecules were immediately released from HAp-MB, whilst an initial burst release of MB from HAp-MB@TA was followed by a sustainable and pH-sensitised release. In comparison with HAp-MB, photocatalystic reduction of HAp-MB@TA by titanium dioxide hardly occurred under illumination, indicating the stability against reduction to leukomethylene blue in vitro. Generation efficiency of singlet oxygen by MB released from HAp-MB@TA was significantly higher than that from HAp-MB because of the control of TA and Fe(III) ions complexes on molecular structures of released MB.

A facile method was herein demonstrated to optimise the generation efficiency of singlet oxygen by controlling aggregation states of PS molecules and improve PDT efficiency to damage tumour tissues.

The purpose of this paper is to provide a comprehensive review and critique of what we already know about pay systems in Chinese state‐owned enterprises, to identify the gaps in the literature and to stimulate more research in this area.

The paper first describes the policy issues at the macro‐level (government policies) in order to put micro‐level pay practices in a pertinent context. Then the paper provides a detailed review and critique on current empirical studies on pay practices in Chinese enterprises, their antecedents and consequences. Finally, the paper identifies potential research questions and provides some directions for future research.

The paper concludes from the extensive review of the current literature that the following research areas merit attention: Why do some firms pay their employees more than other firms? Why do we observe different types of internal pay structures among firms? What are the consequences of these different structures? Why is the link between pay and performance weak in some firms but strong in others? Under what conditions pay‐for‐performance enhances firm performance?

The paper is one of the most comprehensive reviews of the literature on compensation practices of Chinese companies.

Extant research on the crowding-out effects of government subsidies on the positive role of firm innovation resources or activity remains limited. This paper aims to investigate the crowding-out effects of subsidies on the utilization of technological capabilities and also the contingency mechanisms of market-oriented economy based on the resource-based view (RBV), given the co-existence of the subsidies and technological capabilities for firm innovation in transitional economy.

This paper used panel data of 115 Chinese high-tech firms from 2002 to 2010. Fixed-effects model was used to test several hypotheses.

This paper empirically demonstrates that the subsidies crowd out the utilization of firms’ technological capabilities for invention outcomes in the near-term. Furthermore, this paper finds that the crowding-out effects are weaker when firms have high export intensity or are located in provinces with high market-oriented systems.

The findings of this paper apply to Chinese firms. Future research could test their generalizability to different samples and other transitional economies.

This paper highlights the crowding-out effects of the subsidies, revealing that high-tech firms should balance the direct effects and crowding-out effects of the subsidies.

This paper highlights the neglected interactions between the subsidies and technological capabilities based on RBV and provides a more nuanced understanding of the crowding-out effects of the subsidies in transitional economy.