Cytotoxic effects of ZnO hierarchical architectures on RSC96 Schwann cells

The alteration in intracellular Zn(2+) homeostasis is attributed to the generation of intracellular reactive oxygen species, which subsequently results in oxidative damage of organelles and cell apoptosis. In this work, the neurotoxic effects of ZnO hierarchical architectures (nanoparticles and microspheres, the prism-like and flower-like structures) were evaluated through the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay using RSC96 Schwann cells as the model. Cell apoptosis and cell cycle were detected using flow cytometry. The concentration of Zn(2+) in the culture media was monitored using atomic absorption spectrometry. The results show that ZnO nanoparticles and microspheres displayed significant cytotoxic effects on RSC96 Schwann cells in dose- and time-dependent manners, whereas no or low cytotoxic effect was observed when the cells were treated with the prism-like and flower-like ZnO. A remarkable cell apoptosis and G2/M cell cycle arrest were observed when RSC96 Schwann cells were exposed to ZnO nanoparticles and microspheres at a dose of 80 μg/mL for 12 h. The time-dependent increase of Zn(2+) concentration in the culture media suggests that the cytotoxic effects were associated with the decomposition of ZnO hierarchical architecture and the subsequent release of Zn(2+). These results provide new insights into the cytotoxic effects of complex ZnO architectures, which could be prominently dominated by nanoscale building blocks

Environmental filtering, spatial processes and biotic interactions jointly shape different traits communities of stream macroinvertebrates

The metacommunity concept has been widely used to explain the biodiversity patterns at various scales. It considers the influences of both local (e.g., environmental filtering and biotic interactions) and regional processes (e.g., dispersal limitation) in shaping community structures. Compared to environmental filtering and spatial processes, the influence of biotic interactions on biodiversity patterns in streams has received limited attention. We investigated the relative importance of three ecological processes, namely environmental filtering (including local environmental and geo-climatic factors), spatial processes and biotic interactions (represented by interactions of macroinvertebrates and diatom), in shaping different traits of macroinvertebrate communities in subtropical streams, Eastern China. We applied variance partitioning to uncover the pure and shared effects of different ecological processes in explaining community variation. The results showed that environmental filtering, spatial processes, and biotic interactions jointly determined taxonomic and trait compositions of stream macroinvertebrates. Spatial processes showed a stronger influence in shaping stream macroinvertebrate communities than environmental filtering. The contribution of biotic interactions to explain variables was, albeit significant, rather small, which was likely a result of insufficient representation (by diatom traits) of trophic interactions associated with macroinvertebrates. Moreover, the impact of three ecological processes on macroinvertebrate communities depends on different traits, especially in terms of environmental filtering and spatial processes. For example, spatial processes and environmental filtering have the strongest effect on strong dispersal ability groups; spatial processes have a greater effect on scrapers than other functional feeding groups. Overall, our results showed that the integration of metacommunity theory and functional traits provides a valuable framework for understanding the drivers of community structuring in streams, which will facilitate the development of effective bioassessment and management strategies.Peer Reviewe

Environmental filtering, spatial processes and biotic interactions jointly shape different traits communities of stream macroinvertebrates

The metacommunity concept has been widely used to explain the biodiversity patterns at various scales. It considers the influences of both local (e.g., environmental filtering and biotic interactions) and regional processes (e.g., dispersal limitation) in shaping community structures. Compared to environmental filtering and spatial processes, the influence of biotic interactions on biodiversity patterns in streams has received limited attention. We investigated the relative importance of three ecological processes, namely environmental filtering (including local environmental and geo-climatic factors), spatial processes and biotic interactions (represented by interactions of macroinvertebrates and diatom), in shaping different traits of macroinvertebrate communities in subtropical streams, Eastern China. We applied variance partitioning to uncover the pure and shared effects of different ecological processes in explaining community variation. The results showed that environmental filtering, spatial processes, and biotic interactions jointly determined taxonomic and trait compositions of stream macroinvertebrates. Spatial processes showed a stronger influence in shaping stream macroinvertebrate communities than environmental filtering. The contribution of biotic interactions to explain variables was, albeit significant, rather small, which was likely a result of insufficient representation (by diatom traits) of trophic interactions associated with macroinvertebrates. Moreover, the impact of three ecological processes on macroinvertebrate communities depends on different traits, especially in terms of environmental filtering and spatial processes. For example, spatial processes and environmental filtering have the strongest effect on strong dispersal ability groups; spatial processes have a greater effect on scrapers than other functional feeding groups. Overall, our results showed that the integration of metacommunity theory and functional traits provides a valuable framework for understanding the drivers of community structuring in streams, which will facilitate the development of effective bioassessment and management strategies

Decreased ventricular systolic function in chemotherapy-naive patients with acute myeloid leukemia: a three-dimensional speckle-tracking echocardiography study

BackgroundThe relationship between acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL) and cardiac function is not well established. This study aimed to evaluate whether AML patients exist early myocardial damages prior to chemotherapy and to investigate its association with cardiovascular biomarkers.MethodsConventional echocardiography and three-dimensional speckle-tracking strain analysis were performed prospectively in 72 acute leukemia (AL) patients before any chemotherapy therapy (of whom 44 were AML patients, 28 ALL patients). The results were compared with those from 58 control group matched for age and gender.ResultsThere were no significant differences in conventional biventricular systolic function parameters between AL patients and controls. The left ventricular global longitudinal strain (LVGLS) and right ventricular free wall longitudinal strain (RVFWLS) were significantly lower in AL patients (−23.0 ± 1.4% vs. −24.1 ± 1.3% and −27.9 ± 7.1% vs. −33.0 ± 4.6%, respectively, P < 0.001 for all). Compared with ALL patients, AML patients had lower LVGLS and RVFWLS (−22.7 ± 1.3% vs. −23.5 ± 1.6% and −26.2 ± 7.6% vs. −30.4 ± 5.5%, respectively, P < 0.05 for all). LVGLS was lower in ALL patients compared with controls (−23.5 ± 1.6% vs. −24.7 ± 1.4%, P < 0.05), however, there was no difference in right ventricular systolic function parameters between the two groups. LVGLS in AL patients was independently correlated with left ventricular ejection fraction (LVEF) and the absolute number of circulating lymphocytes.ConclusionsOur findings suggest that baseline myocardial systolic function is lower in AL patients than controls. AML patients had lower baseline LVGLS and RVFWLS than controls and ALL patients. The decreased LVGLS is correlated with LVEF and the absolute number of circulating lymphocytes

Multi-material topology optimisation of micro-composites with reduced stress concentration for optimal functional performance

This study develops a new multi-material topology optimisation framework for design of periodic micro-composites with optimal functional performance and reduced stress concentration. First, multi-material topology optimisation is developed based on the alternating active phase algorithm and inverse homogenisation method with the sensitivity analysis derived for specific property objective i.e., negative Poisson's ratio (NPR) or maximum effective bulk modulus (EBM) and (p-norm macroscopic) stress objective. Then, the effects of initial material distribution and weight ratio (w1, w2 assigned to the property and stress objectives, respectively) are investigated, and the evaluation indices are also developed to obtain the optimal solution. Further, two cases related to the design of micro-composites for maximised either NPR or EBM with reduced maximum stress are performed. The results show that when designing the multi-material NPR micro-composites, the decrease of w1/w2 contributes to a general decease of both NPR and maximum stress. While in designing the maximum EBM, decreasing w1/w2 leads to the reduced maximum stress and simultaneously reduced EBM; hereby, a decision-making method as well as the proposed evaluation index are both applied and compared for acquiring the optimal result. This study provides new methods and solutions to multi-material micro-composites design for future industrial applications

Toughening mechanisms for fiber-reinforced polymer-reinforced concrete beams

The bond between reinforcing bars and the surrounding concrete is one of the dominant mechanisms affecting the structural behaviour of fiber-reinforced polymer (FRP)-reinforced concrete structures. In this chapter, the experimental and numerical studies on the bond mechanism between FRP rebars and concrete in FRP-reinforced concrete beams are presented. Concrete beams reinforced with three types of FRP rebars with different rebar surfaces were tested under four-point bending loads to investigate the effects of types and surface conditions of FRP rebars on the bond-slip behaviour of reinforced concrete beams. A new finite element model recently developed and validated by the authors was employed to numerically investigate the bond-slip behaviour of FRP-reinforced concrete beams and the effects of different rebar surfaces and different rebar types on the bond-slip behaviour. The results are presented and the toughening mechanism between FRP rebars and concrete is analyzed

Toughening mechanisms for fiber-reinforced polymer-reinforced concrete beams

The bond between reinforcing bars and the surrounding concrete is one of the dominant mechanisms affecting the structural behaviour of fiber-reinforced polymer (FRP)-reinforced concrete structures. In this chapter, the experimental and numerical studies on the bond mechanism between FRP rebars and concrete in FRP-reinforced concrete beams are presented. Concrete beams reinforced with three types of FRP rebars with different rebar surfaces were tested under four-point bending loads to investigate the effects of types and surface conditions of FRP rebars on the bond-slip behaviour of reinforced concrete beams. A new finite element model recently developed and validated by the authors was employed to numerically investigate the bond-slip behaviour of FRP-reinforced concrete beams and the effects of different rebar surfaces and different rebar types on the bond-slip behaviour. The results are presented and the toughening mechanism between FRP rebars and concrete is analyzed

Nonlinear finite element analysis of composite steel/FRP-reinforced concrete beams using a new beam element

In this paper, a simple and computation effective one-dimensional two-node beam element is developed based on the Timoshenko’s beam functions and layered approach for nonlinear finite element analysis of structural behaviour of composite steel/FRP-reinforced concrete beams. Both geometric nonlinearity and material nonlinearity are accounted for in the nonlinear finite element model, and Timoshenko’s composite beam functions are employed to represent the transverse displacement and rotation of the element. The agreement of the computed results for steel and FRP reinforced concrete beams with those obtained from experimental study and other numerical analysis demonstrate the efficiency and accuracy of the proposed element model

A new one-dimensional two-node layered composite beam element

A simple one-dimensional two-node beam element is developed in this paper based on Timoshenko’s composite beam functions. To account for the layered characterization of the composite beams, a layered method is employed in the proposed element. The proposed element provides a unified formulation for both slender and moderately deep beam analyses, and the notorious shear locking phenomenon for analysis of slender beams can be avoided naturally. The proposed beam element is demonstrated to be efficient and accurate for both isotropic and composite beams analyses by numerical examples

Parametric study of FRP-strengthened reinforced concrete panels under blast loads

The use of fibre reinforced polymer (FRP) as a strengthening material for reinforced concrete structures to resist blast loads has attracted great interests in recently years. The structural responses of FRP-strengthened reinforced concrete panels under blast loads are investigated intensively in this paper by employing a finite element model recently developed by the authors. The effects of the thickness of the strengthening FRP sheet, the retrofitted surface, the standoff distance and the mass of the charge on the structural behavior of the reinforced concrete panels under blast loads are studied. The results of the parametric study are analyzed and presented in this paper