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This paper provides a new fractional boundary element method (BEM) solution for nonlinear nonlocal thermoelastic problems with anisotropic fibrous polymer nanoparticles. This comprehensive BEM solution comprises two solutions: the anisotropic fibrous polymer nanoparticles problem solution and the nonlinear nonlocal thermoelasticity problem. The nonlinear nonlocal thermoelasticity problem solution separates the displacement field into complimentary and specific components. The overall displacement is obtained using the boundary element methodology, which solves a Navier-type problem, and the specific displacement is derived using the local radial point interpolation method (LRPIM). The new modified shift-splitting (NMSS) technique, which minimizes memory and processing time requirements, was utilized to solve BEM-created linear systems. The performance of NMSS was evaluated. The numerical results show how fractional and graded parameters influence the thermal stresses of nonlinear nonlocal thermoelastic issues involving anisotropic fibrous polymer nanoparticles. The numerical findings further reveal that the BEM results correlate very well with the finite element method (FEM) and analytical results, demonstrating the validity and correctness of the proposed methodology. [ABSTRACT FROM AUTHOR]

This paper provides a new fractional boundary element method (BEM) solution for nonlinear nonlocal thermoelastic problems with anisotropic fibrous polymer nanoparticles. This comprehensive BEM solution comprises two solutions: the anisotropic fibrous polymer nanoparticles problem solution and the nonlinear nonlocal thermoelasticity problem. The nonlinear nonlocal thermoelasticity problem solution separates the displacement field into complimentary and specific components. The overall displacement is obtained using the boundary element methodology, which solves a Navier-type problem, and the specific displacement is derived using the local radial point interpolation method (LRPIM). The new modified shift-splitting (NMSS) technique, which minimizes memory and processing time requirements, was utilized to solve BEM-created linear systems. The performance of NMSS was evaluated. The numerical results show how fractional and graded parameters influence the thermal stresses of nonlinear nonlocal thermoelastic issues involving anisotropic fibrous polymer nanoparticles. The numerical findings further reveal that the BEM results correlate very well with the finite element method (FEM) and analytical results, demonstrating the validity and correctness of the proposed methodology.

The sinusoidal four-variable shear deformation shell theory is employed, for the first time, to investigate the size dependent electro-hygrothermal bending of functionally graded (FG) sandwich piezoelectric cylindrical shells integrated with porous core. This model is assumed to be rested on two-parameter elastic foundations and subjected to elevated temperature, moisture concentration and external electric voltage as well as transverse mechanical loads. In order to take into account the size effect, the modified couple stress theory is employed containing only one length scale parameter. The core layer is assumed to be functionally graded porous material. Whereas, the face sheets are made of a functionally graded piezoelectric material which having gradient change along the thickness direction. Based on the sinusoidal four-variable shell theory, four governing equations are obtained involving external forces and foundation interaction, in addition to an equation associated to the electrical potential. An analytical solution for the obtained equations is presented to get the displacements and stresses of the FG sandwich piezoelectric cylindrical shells. Influences of the geometric parameters, material length scale parameter, temperature rise, moisture concentration, electric voltage, porosity factor, core thickness and foundation coefficients on the bending of the FG sandwich piezoelectric cylindrical shells resting on elastic foundations are discussed.

In this paper, the coupled bending and torsional vibration analysis of microbeams under axial force based on Timoshenko's beam theory is investigated. Modified non-classic coupled stress theory and the Hamilton principle used to establish the motion equations of the system. The generalized differential quadratures method is used to solve the obtained set of differential equations. After establishment of eigenvalue problem, two comparison studies are conducted to assure the validity and accuracy of the present solution and excellent agreement observed with the present results and those reported by other researchers in some specific cases by analytical solutions and classical beam theory. Afterwards, parametric studies are developed to examine the influences of boundary conditions, size effect, and various geometric characteristics of the beam on natural frequencies and the associated mode shapes are discussed. The results show that the non-compliance of the mass axis with the elastic axis reduces the natural frequency. Also, Poisson's ratio have an opposite effect on the natural frequency. [ABSTRACT FROM AUTHOR]

By hindering migration and inducing direct turbine mortality during downstream migration, hydropower is regarded as one of the most serious threats to anadromous salmonids. Yet, little attention has been paid to long-term turbine-induced selection mechanisms effecting fish populations. This work evaluates turbine and post-turbine survival of PIT-tagged wild brown trout smolts. By estimating individual river and sea survival rates, we were able to compare survival rates of smolts that had migrated through the turbine with smolts that had bypassed the turbine, as well as investigate both natural and anthropogenic size-selective mechanisms operative on the population. Total river-descent survival probability was 0.20 for turbine migrants and 0.44 for bypass migrants. The surviving turbine migrants were significantly smaller than their bypass counterparts and more exposed to predation from Northern pike. The estimated mean-adjusted selection gradient was − 0.76 for turbine migrants and + 1.85 for the bypass migrants. The resulting disruptive selection may ultimately lead to increased phenotypic smolt size variation provided sufficient additive genetic variance associated with smolt size. Mitigation measures at hydropower plants are thus essential for preserving sustainable populations of anadromous fish and maintaining population genetic variation. [ABSTRACT FROM AUTHOR]

The 3DOM TiO 2 -Au-CdS inverse opal photonic crystal structure is designed for visible-light hydrogen production, exhibiting extremely enhanced photocatalytic activity via coupling bifunctional SPR effect and electron transfer of Au NPs with slow photon effect. [Display omitted] • The ternary TiO 2 -Au-CdS (TAC) photocatalysts have been designed to couple the bifunctional Au NPs with slow photon effect. • A two electron transfer paths model is proposed in the ternary TAC photocatalysts. • Finite-difference time-domain (FDTD) simulations are used to reveal the size effect of Au NPs. • The ternary TAC-10 photocatalyst with ~ 10 nm Au NPs demonstrates the highest hydrogen evolution rate under visible-light. Gold nanoparticles (Au NPs) with surface plasmonic resonance (SPR) effect and excellent internal electron transfer ability have widely been combined with semiconductors for photocatalysis. However, the in-depth effects of Au NPs in multicomponent photocatalysts have not been completely understood. Herein, ternary titanium oxide-gold-cadmium sulfide (TiO 2 -Au-CdS, TAC) photocatalysts, based on hierarchical TiO 2 inverse opal photonic crystal structure with different Au NPs sizes have been designed to reveal the SPR effect and internal electron transfer of Au NPs in the presence of slow photon effect. It appears that the SPR effect and internal electron transfer ability of Au NPs, depending on their sizes, play a synergistic effect on the photocatalytic enhancement. The ternary TAC-10 photocatalyst with ~ 10 nm Au NPs demonstrates an unprecedented hydrogen evolution rate of 47.6 mmolh-1g−1 under visible-light, demonstrating ~ 48% enhancement comparing to the sample without slow photon effect. In particular, a 9.83% apparent quantum yield under 450 nm monochromatic light is achieved for TAC-10. A model is proposed and finite-difference time-domain (FDTD) simulations reveal the size influence of Au NPs in ternary TAC photocatalysts. This work suggests that the rational design of bifunctional Au NPs coupling with slow photon effect could largely promote hydrogen production from visible-light driven water splitting. [ABSTRACT FROM AUTHOR]

We studied adult zebrafish to determine whether the size of 20 and 110 nm citrate-coated silver nanoparticles (AgC NPs) differentially impact the gills and intestines, known target organs for Ag toxicity in fish. Following exposure for 4 h, 4 days, or 4 days plus a 7 day depuration period, we obtained different toxicokinetic profiles for different particle sizes, as determined by Ag content of the tissues. Ionic AgNO3 served as a positive control. The gills showed a significantly higher Ag content for the 20 nm particles at 4 h and 4 days than the 110 nm particles, while the values were more similar in the intestines. Both particle types were retained in the intestines even after depuration. These toxicokinetics were accompanied by striking size-dependent differences in the ultrastructural features and histopathology in the target organs in response to the particulates. Ag staining of the gills and intestines confirmed prominent Ag deposition in the basolateral membranes for the 20 nm but not for the 110 nm particles. Furthermore, it was possible to link the site of tissue deposition to disruption of the Na(+)/K(+) ion channel, which is also localized to the basolateral membrane. This was confirmed by a reduction in ATPase activity and immunohistochemical detection of the α subunit of this channel in both target organs, with the 20 nm particles causing significantly higher inhibition and disruption than the larger size particles or AgNO3. These results demonstrate the importance of particle size in determining the hazardous impact of AgNPs in the gills and intestines of adult zebrafish.

In the framework of nonlocal strain gradient theory, a size-dependent symmetric and sigmoid functionally graded (FG) Timoshenko beam model is developed to study and analyze the free vibration and dynamic response under moving load, for the first time. To incorporate the size-dependent effect, the nonlocal strain gradient theory is adopted. The Hamilton principle is employed to drive the dynamic equations of motion and the associated boundary conditions. Based on Navier's approach, an analytical solution methodology for free and forced vibration problems is developed. The developed methodology is verified by comparing the obtained results with the available resources and good agreement is observed. Numerical results are obtained and discussed. Effects of the material gradation index, nonlocal parameter, microstructure length scale parameter, and the nondimensional velocity parameter of the moving load on the dynamic behavior are investigated. It is found that these variables significantly affect the dynamic behavior of the functionally graded nanobeams, and they could be adjusted to control this behavior. Obtained results are supportive of the design and control of such types of structural components. [ABSTRACT FROM AUTHOR]

The feasibility to synthesize the ligand‐protected atomically precise nanoclusters with various compositions in sub‐nanometer range (≤2 nm) and the determination of their structures is an important step in long‐pursuit of well‐defined heterogeneous catalysis. Such types of precise catalysts provide an opportunity to understand the fundamentals of catalysis better in terms of: 1) activity and selectivity by metal‐core and metal‐ligand interface, 2) size‐dependent activity, 3) reaction mechanism and 4) active‐site identification and activation. It motivated us to develop the novel metal nanoclusters with precise structures as the new catalytic systems, which led to the several significant findings on above mentioned points. We consider that with this gained knowledge, the future research is expected to bring more exciting advancement in deep understanding of the reaction mechanism, specific‐site identification and tailoring of catalytic active sites at atomic level. [ABSTRACT FROM AUTHOR]

Many studies focus on the relationships between plant functional traits and tree growth performances. However, little is known about the ontogenetic shifts of the relationships between functional traits and tree growth. This study examined associations between stem and leaf functional traits and growth rates and their ontogenetic shifts across 20 tropical tree species in a tropical seasonal rainforest in Xishuangbanna, south-west China. For each species, physiological active branches of individual trees belonged to three size classes (i.e. small, diameter at breast height (DBH) 5–10 cm; middle, DBH 10–20 cm; big, DBH >20 cm) were sampled respectively. We measured 18 morphological and structural traits, which characterised plant hydraulic properties or leaf economic spectrum. Associations between diameter growth rates and functional traits were analysed across three size classes. Our results revealed that diameter growth rates of big-sized trees were mainly related to traits related to plant hydraulic efficiency (i.e. theoretical hydraulic conductivity (Ktheo) and leaf vein density (Dvein)), which suggests that the growth of large trees is limited mainly by their xylem water transport capacity. For middle-sized trees, growth rates were significantly related to traits representing leaf economic spectrum (i.e. specific leaf area (SLA), individual leaf mass (ILM), palisade thickness (PT) and spongy thickness (SP)). Diameter growth rates of small-sized trees were not correlated with hydraulic or leaf economic traits. Thus, the associations between tree growth rates and functional traits are size dependent. Our results suggest ontogenetic shift of functional traits which could potential contribute to different growth response to climate change. Plant functional traits can directly reflect plants performance under environmental. We show that traits growth relationships are strongly size-dependent in tropical rainforest in south-west China: diameter growth rates correlated significantly with leaf economic spectrum traits for middle sized trees, but for large sized trees hydraulic efficiency traits play a more important role on growth. This suggests ontogenetic shift of functional traits could potential contribute to different growth response to climate change. [ABSTRACT FROM AUTHOR]

Thermoelastic damping (TED) is one of the main internal energy dissipation mechanisms in micro-/nano-resonators. Accurate evaluation of TED is important in the design of micro-electromechanical systems and nano-electromechanical systems. In this paper, a theoretical analysis on the TED in functionally graded material (FGM) micro-beam resonators is presented. Equations of motion and the heat conduction equation governing the thermodynamic coupling free vibration of non-homogenous micro-beams are established based on the Euler–Bernoulli beam theory associated with the modified couple stress theory. Material properties of the FGM micro-beam are assumed to change in the depth direction as power-law functions. The layer-wise homogenization method is used for solving the heat conduction equation. By using the mathematical similarity of eigenvalue problem between the FGM beam and the reference homogeneous one, the complex natural frequency including TED is expressed in terms of the natural frequency of the isothermal homogenous beam. In the presented numerical results, influences of various characteristic parameters, such as beam thickness, material gradient index, structure size, vibration mode and boundary conditions, on TED are examined in detail. It shows that TED decreases with the increases in the values of length scale parameters because the latter lead to the increase in structural stiffness. [ABSTRACT FROM AUTHOR]

The article analysis the free axial vibration, the time-dependent and forced axial vibration of a Single walled carbon nanotube (SWCNT) subjected to a moving load. Topics include the study of forced axial vibrations caused due to the axial moving harmonic force based on Eringen's nonlocal elasticity theory; and the use of Hamilton's principle.

In this paper, nonlinear free vibration analysis of micro-beams resting on the viscoelastic foundation is investigated by the use of the modified couple stress theory, which is able to capture the size effects for structures in micron and sub-micron scales. To this aim, the gov-erning equation of motion and the boundary conditions are derived using the Euler–Bernoulli beam and the Hamilton’s principle. The Galerkin method is employed to solve the governing nonlinear differential equation and obtain the frequency-amplitude algebraic equation. Final-ly, the effects of different parameters, such as the mode number, aspect ratio of length to height, the normalized length scale parameter and foundation parameters on the natural fre-quency-amplitude curves of doubly simply supported beams are studied.

In this letter, a model of strain-induced nanomagnet at room temperature is established to explore the effect of size error on the reliability of straintronic memory and spin neurons. The results show that the relationship between input voltages and 180° magnetization switching probability (activation function) of the nanomagnet has a size dependence. The slope of the activation function is related only to the aspect ratio of the nanomagnet, and the thickness error will not affect its slope. The slope of the activation function will decrease as the aspect ratio increases. At the same time, the offset of the activation function increases with the increasing energy barrier (increase in thickness or decrease in aspect ratio) of the nanomagnet. We found that a slight dimensional error will also significantly reduce the reliability of straintronic memory. Increasing the fabrication accuracy or changing the input voltages can solve this problem. We further studied the relationship between the size error and the reliability of spin neurons by using different size spintronic neural networks for handwritten digits recognition under the same input voltages. We found that the size error has a minor effect on the spin neuron's neurologic computing function. A thickness error of 3 nm or a width error of 8 nm will not affect the recognition accuracy of the spintronic neural network. In other words, straintronic spin neurons are more tolerant to dimensional errors and more reliable than strain memory, and its fabrication accuracy requirements can be lower. These findings can provide important guidance for the design of straintronic spin neuron and memory. [ABSTRACT FROM AUTHOR]

In the present paper, low velocity impact response of a size-dependent nanobeam in a thermal field with uniform temperature distribution has been investigated. The van-der Waals interaction force based on description of Lennard–Jonses is considered as the impact force between nanoparticle and nanobeam. According to third-order shear deformation beam theory, the governing equations are obtained using Hamilton's principle based on nonlocal strain-gradient theory. The Galerkin's method was adopted to solve the differential equations of nanobeam with simply supported and clamped boundary conditions. Afterward, the system of time-dependent equations by applying the fourth-order Runge–Kutta method is solved. The parametric study is presented to examine the effect of particle radius, initial velocity, temperature environment, the nonlocal parameter, and the length-scale parameter on the impact response of nanobeam. [ABSTRACT FROM AUTHOR]

Graphene oxide membranes (GOMs), consisting of graphene oxide (GO) laminar microstructures, offer great potential as nanofiltration membranes due to their unique laminar nanochannelled galleries created between the stacked GO flakes. Recently, GOMs made from smaller GO flakes (S-GOMs) were favored for the reason that the less tortuous transport pathways could render better water permeability. Here, we found that this may not necessarily be true. We designed experiments, which suggested that the interlayer spacing between GO flakes may be a more important factor affecting the water permeability than the tortuosity of the water pathway, especially when the two-dimensional nanochannels were smaller than expected under a pressurized filtration setting. Notably, our results showed that as the GO flakes were fragmented into smaller pieces by high-power probe sonication, they underwent a thermal reduction that decreased the size of the interlayer spacing. Coupled with a less wrinkled microstructure that caused tighter compaction under a 3-bar transmembrane pressure, the overall water transport through the S-GOM was reduced despite a less tortuous pathway that was 2.5 times shorter based on theoretical calculation. This led to S-GOM showing 3.3 times lower water permeability than that of GOM made from large GO flakes. On the whole, our results unveil the interplay between the two most important parameters governing the water permeability of GOMs, which will help researchers with more instructional support when developing better performing GOMs for nanofiltration application. [Display omitted] • Three different sizes of GO flakes were used: small, medium and large. • GO membrane from small flakes (S-GOM) showed 2.5 times shorter pathway. • S-GOM exhibited 3.3 times lower water permeability surprisingly. • We attributed this to the smaller interlayer spacing of S-GOM. • The less wrinkled microstructure also contributed to more severe compaction under pressure. [ABSTRACT FROM AUTHOR]

The blood-brain barrier (BBB) is a limiting factor in nanoparticle drug delivery to the brain, and various attempts have been made to overcome it for efficient drug delivery. Nowadays, it was considered as further issue for brain-drug delivery that the nanoparticle delivered to brain through the BBB reach cancer cells in tumour tissue. In this study, we investigated the effect of nanoparticle size on blood-brain tumour barrier (BBTB) permeation of fluorescence-labelled gold nanoparticles (AuNPs) in a mouse model of orthotopic glioblastoma multiforme (GBM), established by intracranial implantation of luciferase-expressing human glioblastoma U87MG cells. AuNPs sized 10, 50, and 100 nm were perfused into the GBM mice via internal carotid artery (ICA) for 5 min. Immediately after perfusion, the brains were fixed and prepared for LSCM observation. The AuNPs distribution in the normal and tumorous brain tissues was analysed qualitatively and quantitatively. Higher distribution of AuNPs was observed in the tumorous tissue than in the normal tissue. Furthermore, the smallest nanoparticle, 10 nm AuNPs, was widely distributed in the brain tumour tissue, whereas the 50 and 100 nm AuNPs were located near the blood vessels. Therefore, nanoparticle size affected the permeation of nanoparticles from the blood into brain tumour tissue. [ABSTRACT FROM AUTHOR]

Abstract Determination of trace amounts of uranyl ions is of great significance to environment and human health, but challenging. In this paper, we demonstrate a new approach for highly effective determination of uranyl ions by the probe of CdTe quantum dot (QD) with a specific size. The selectivity is relied on the probe of CdTe quantum dots; the selectivity, which was a function of QDs size, was optimum at 6.8 nm. The probe has a detection limit of 7.88 × 10−9 mol L−1 and responded linearly to uranyl ion concentration in the range of 2.36 × 10−8 mol L−1 ~ 4.00 × 10−7 mol L−1. The mechanism can be probably attributed to the fact that uranyl ions could react with Te(0) on the surface of the quantum dots as large as 6.8 nm, resulting in fluorescence quenching. This work provides a new approach to detect uranyl ions in the aqueous solution by doing strip and real sample tests, and indicated the promise of this approach for real-time and in-situ detection of uranyl ions. Graphical abstract fx1 Highlights • A new strategy is developed for trace uranyl detection by CdTe quantum dot. • The selectivity is dependent on the size of quantum dots, and ~6.8 nm is the best. • There is a linear determination with uranyl concentration from 2.4 to 40 × 10−8 mol L−1. • Uranyl ion can coordinate with Te(0) on the surface of CdTe dot as large as 6.8 nm. • Visual distinguishing of uranyl ions is achieved by a simple strip test. [ABSTRACT FROM AUTHOR]

Understanding the real nature of the intrinsic electrocatalytic performance of the counter electrode is crucial for realizing high conversion efficiency of solar energy in photoelectric devices. However, owing to the average effects, a thorough insight into such electrocatalytic process remains challenging in ensemble measurements. Here, we realized the real‐time detection of electrocatalytic reduction of a single Au nanoparticle (NP) in sulfide/polysulfide redox electrolyte solution using single entity collision electrochemistry. Owing to the high‐sensitivity electrochemical measurement, size‐dependent electrocatalytic behaviors of polysulfide reduction were observed for single AuNP collision. Our approach allowed the electrocatalytic properties of AuNPs for polysulfide electrolyte reduction at the single NPs level to be quantified, and the turnover number as a function of particle size were further estimated. Our result has further pointed out the importance of NP size control in the electrocatalysis study. Intrinsic electrocatalytic activity: the introduced electrochemical method could be used for investigating the intrinsic catalytic activity of different sized Au nanoparticles and quantifying electrocatalytic performance of a single Au nanoparticle, providing new insights to facilitate the fabrication of electrocatalysts with increased performance. [ABSTRACT FROM AUTHOR]

Mercury ion (Hg 2+ ) is a highly hazardous and widespread pollutant with bio-accumulative properties. Although the existing Hg 2+ detection methods have high sensitivity and reliability, whereas there have few reports concerning bimodal detection for Hg 2+ with one sensor. Toward this goal, a novel sensor based on rhodamine derivatives (RhD) grafted AuNS@Ag core-shell nanocubes (CSN) has been synthesized and shown the bimodal detection capabilities with metal enhanced fluorescence (MEF) and surface enhanced Raman scattering (SERS) for Hg 2+ . Herein, resultant CSN acts as the signal enhancing material; RhD was modified on the outside of the shell to ensure the signal sensitive of the CSN-RhD hybrids. In this work, we investigate the size- and shape-dependent SERS activity of plasmonic CSN comprised of AuNS as cores and Ag cuboids as shells. The SERS activity of CSN with spherical core was found to increase with the increasing thickness of the Ag cubic shell. Sequel, under an optimized condition, a display of strong MEF and SERS signals of the resulting mixtures with increasing of Hg 2+ concentrations was observed. The proposed bimodal sensor showed excellent performances for Hg 2+ along with wide linear range of 0.001–1000 ppm and 0.01–1000 ppm as well as the relatively low detection limit of 0.94 and 5.16 ppb for MEF and SERS assays, respectively. Furthermore, the ability of the sensor to detect Hg 2+ was also confirmed in adulterated milk samples. [ABSTRACT FROM AUTHOR]

A theoretical study is conducted on the fracture behavior of a cracked equilateral triangle hole with surface effect subjected to far-field antiplane mechanical load and inplane electric load. A rigorous analytical solution to the stress and electric displacement fields are obtained based on the theory of Gurtin-Murdoch surface model and conformal mapping technique. A closed form solution to the stress intensity factor, the electric displacement intensity factor and the energy release rate at the tip of crack are presented. Numerical examples are provided to reveal the variations of the electroelastic field intensity factors and the energy release rate with the size of triangle hole, the length of crack and the applied mechanical load and electrical load. The major results of the study are as follows: (1) The electroelastic field intensity factors at crack tip are dramatically size dependent when the size of the cracked triangle hole is at nanoscale. The present solution approaches classical electroelastic theory when the length of cracked equilateral triangle hole has large characteristic dimensions. (2) With the increase of the length of crack, the electroelastic field intensity factors first increase rapidly, and then slowly decrease, and finally stabilize. (3) When considering surface effect, the stress and electric displacement intensity factors depend on the applied mechanical-electrical loads, which is different from that of the classical electroelastic fracture theory. (4) The normalized energy release rate increases with the increase of the size of the cracked triangle hole. (5) The influences of the applied mechanical load on the normalized energy release rate depend on whether the applied electrical load is positive or negative. (6) With the increase of the applied electrical load from negative to positive, the normalized energy release rate release rate first increases and then decreases. Very high positive and negative applied electrical loads shield the normalized energy release rate. [ABSTRACT FROM AUTHOR]