Search

Nanoscaled metal organic frameworks have emerged as a novel type of organic-inorganic hybrid coordination polymeric nanomaterials and showed great promise in biomedical area in recent decades. As a special subclass, zeolitic imidazolate frameworks (ZIFs), constructing with metal ions and imidazolate linkers, own unique advantages of high porosity, large surface area, good biocompatibility, pH sensitivity and etc. These render ZIFs as attractive and promising platforms to delivery various cargos of drugs, imaging probes and biomacromolecules for cancer diagnosis and therapy. And this review specially summaries the state-of-the-art research on ZIFs for biosensing, cancer imaging and phototheranostics within the latest 5 years. The multiply strategies of synthesis, characterization and functionalization of ZIFs-based nanosystems are firstly discussed. The vital roles of ZIFs in biosensors, including electrochemical, fluorescent and colorimetric sensors are analyzed. Then, the monomodal and/or multimodal cancer imaging techniques mediated by ZIFs are addressed. Particular emphasis is placed on the ZIFs-based cancer phototheranostics which provide a potential alternative avenue to greatly improve the therapeutic index of cancer. Finally, the future opportunities and challenges of ZIFs are tentatively proposed and discussed from the point of translational medicine.

The dynamics of pipes conveying fluid has become a hot topic in the research field of fluid-structure interactions. Perhaps one of the main reasons why the dynamics of pipes conveying fluid has remained of intense interest to dynamicists is the fact that it displays interesting and sometimes unexpected nonlinear dynamical behavior and it has become a handy tool in developing or testing modern dynamics theory. In physical terms, the dynamical system of a loosely supported pipe conveying fluid is an example of large class of problems involving self-excited oscillations and interactions with loose constraints. Hence, understanding and modeling the dynamics of such systems is of both fundamental and practical interests. The two-dimensional (2-D) vibration of a cantilevered pipe conveying fluid has been studied for a long time, but for the moment, only few studies discussed the three-dimensional (3-D) planar and non-planar dynamics of cantilevered pipes subjected to nonlinear loose constraints. This paper establishes the 3-D governing equations and explores the 3-D dynamics of a cantilevered pipe with loose constraints somewhere along its length, with consideration of the friction effect during impacting between the pipe and the loose constraints. The loose constraints consist of two parallel bars (TPBs) on both sides of the pipe in one fixed lateral direction, with free gaps between the pipe and the restraining bars. The impacting force between the pipe and loose constraints is depicted by a smoothened-trilinear spring. In the theoretical analysis, the two governing equations were discretized via Galerkin′s approach and solved using a fourth-order Runge-Kutta method. As the flow velocity becomes sufficiently high, flutter instability of the pipe occurs and limit cycle motions would be generated. When the lateral displacement of the pipe exceeds the free gap, effective impacting occurs. During impacting between the pipe and loose constraints, either static or dynamic friction forces would occur along the other lateral direction. The nonlinear behavior in two perpendicular planes and the influence of friction coefficient were analyzed with special attention. The dynamic responses of the pipe system for various internal flow velocities are exhibited in the form of bifurcation diagrams, time traces and phase plots. Comparisons of the planar and non-planar motions of the pipe with or without loose constraints are conducted for various internal flow velocity ranges. Results show that the constrained pipe is capable of displaying interesting dynamics in the presence of nonlinear impacting force induced by the loose constraints. Both 3-D periodic and quasi-periodic oscillations are observed in a wide range of internal flow velocities. It is found that the introducing of nonlinear impacting constraints slightly enlarges the internal flow velocity range for non-planar motions. It is also shown that the orientation of 2-D planar vibrations of the pipe may be changed with the increase of the friction coefficient. The results obtained in this work may be useful for further understanding other problems in fluid-structure interactions involving slender structures and axial flows, such as the dynamics of slender cylinders in axial flow and deep water risers concurrently subjected to axial and cross flows.

An appropriate assessment of the dynamic behavior of marine propulsion shaft in ships is essential to enable optional delivery of power to the propeller and to minimize unnecessary vibration. Various vibrations coupling with each other can significantly influence the dynamical behavior of the shaft and threaten the reliability of ships. This paper presents a finite element analysis model with multiple constraint conditions to analyze the coupled transverse and longitudinal vibrations of a marine propulsion shaft. Based on this model, in addition to the coupled natural frequencies of each direction, the maximum acceleration are also determined. Furthermore, the simulation of an idling and loading vibration analysis is discussed and validated against experimental results, over a range of rotational speeds. The output of numerical simulation is found to agree with the corresponding results from experimental tests. Finally, an accurate and applicative FEA model for coupled transverse-longitudinal vibration of shaft has been obtained.

A progressive aggregation-induced emission (AIE) strategy is established based on two diverse stimulus-responsive patterns of copper nanoclusters (CuNCs) for imaging of aluminum ions (Al3+) in cellular microenvironment. The non-emissive CuNCs were facilely synthesized with l -glutathione (GSH) as both stabilizing agent and reducing agent, and demonstrated the excellent AIE characteristics in the ethanol/water mixture. Moreover, the dispersed CuNCs can be aggregated to give the AIE behavior in aqueous solutions by reducing the pH value, and could be further aggregated with 94-fold reinforce by introducing Al3+ ascribe to the strong coordination ability between Al3+ and the functional groups of GSH, demonstrating the progressive AIE process. Under endocytosis, the progressive AIE strategy can be employed to distinguish the Al3+ in the locations of lysosome against other organelles due to the acidic microenvironment of lysosome. The progressive AIE advantages of CuNCs provide a new concept for signal transduction, and have the promising applications in decoding the functions of intracellular biomolecules.

Background: The development of bacterial biofilm can cause severe chronic infections and antibiotic resistance. Therefore, it poses a significant threat to public health. Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) are two major pathogens that can cause biofilm-associated infections, which leads to the urgent necessity of developing new agents with biofilm-forming inhibitory ability. Methods: A series of pyran derivatives were synthesized and characterized, and their in vitro anti-biofilm activity against S. aureus and P. aeruginosa were measured by minimal biofilm inhibitory concentration assay and FITC dye staining. The in vivo antibiofilm therapeutical effects were evaluated in S. aureus induced tissue cage infection mice model and P. aeruginosa induced urinary tract catheter infection rat model. Results: Several pyran derivatives showed the in vitro anti-biofilm activity against S. aureus and P. aeruginosa, and the activity of these compounds was not mediated through the accessory gene regulator (agr) quorum sensing system of S. aureus. One of these pyran derivatives, namely 2-amino-4-(2,6-dichlorophenyl)-3-cyano-5-oxo-4H,5H-pyrano[3,2c]chromene, exhibited significant inhibitory biofilm-formation activity in S. aureus tissue cage infection mice model and in the P. aeruginosa-infected urinary tract catheters of experimental rats. Conclusions: The data indicated that this pyran derivative is a possible lead compound that can be used for the development of novel anti-biofilm agents against S. aureus and P. aeruginosa infection. Keywords: Staphylococcus aureus, Pseudomonas aeruginosa, Biofilm, Quorum sensing system, Pyran derivative

It has been well recognised that stress and strain may have significant influences on corrosion. Increasing effort has been made into understanding this so called mechano-electrochemical phenomenon through theoretical, experimental and numerical studies. However, current practice of marine structural analysis often adopts empirically based corrosion models. The majority of these models are derived from historical data and do not explicitly reflect the influence of the actual service conditions such as the mechanical loading. As a result, it is difficult to incorporate realistic corrosion features, often localised and non-uniform, in structural models. This study implemented in situ corrosion experiments into structural strength assessment to incorporate the corrosion-stress interactions over time. This enables the model to capture the dynamic change in thickness reduction spatially and temporally. Bench-shaped features are obtained, closely resembling the corrosion patterns observed in reality. A failure mode change is observed compared to models with uniform thickness reduction.

We analyze Higgs condensate bubble expansion during a first-order electroweak phase transition in the early Universe. The interaction of particles with the bubble wall can be accompanied by the emission of multiple soft gauge bosons. When computed at fixed order in perturbation theory, this process exhibits large logarithmic enhancements which must be resummed to all orders when the wall velocity is large. We perform this resummation both analytically and numerically at leading logarithmic accuracy. The numerical simulation is achieved by means of a particle shower in the broken phase of the electroweak theory. The two approaches agree to the 10\% level. For fast-moving walls, we find the scaling of the thermal pressure exerted against the wall to be $P\sim \gamma^2T^4$, independent of the particle masses, implying a significantly slower terminal velocity than previously suggested., Comment: One minor typo removed on page 7 and one reference updated

Aged marine structural analysis often relies on simplified corrosion modelling. Empirical or statistical methods are used to predict a uniform thickness reduction over time. Although convenient, this approach cannot incorporate the corrosion evolution or the rough surfaces in the damaged area. This is fundamentally due to the lack of representation of the underlying corrosion mechanisms in service environments. To better understand how structural response changes based on corrosion under service loads, this paper presents a series of finite element analyses which consider the coupling relationship between the surface mechanical stresses and the resulting change of corrosion rate. The coupling provide complex corrosion-stress interaction depending on the experimental datasets. The quantification of this interaction is based on in situ experimental measurements of corrosion kinetics at different stress levels. The simulations show the stress effect results in the generation of more realistic corrosion patterns on the structural surface, based on a two-bay/two-span large-scale panel model subject to uniaxial compression. In addition, the incorporation of corrosion experiments allows the modelling of corrosion evolution based on physical observations instead of empirical assumptions. The irregular surface damage leads to a change in structural buckling mode, and up to 8% reduction in ultimate strength compared to models without considering the stress effect.

In this paper, the nonlinear dynamics of a curved pipe is investigated in the case of principal parametric resonance due to pulsating flow and impact with loose supports. The coupled in-plane and out-of-plane governing equations with the consideration of von Karman geometric nonlinearity are presented and discretized via the differential quadrature method (DQM). The nonlinear dynamic responses are calculated numerically to demonstrate the influence of pulsating frequency. Finally, the impact is taken into consideration. The influence of clearance on fretting-wear damage, such as normal work rate, contact ratio and impact force level, is demonstrated.

The aim of this paper is to develop a nonlinear theoretical model for cantilevered micropipes/microbeams conveying fluid and to explore the possible size-dependent nonlinear responses based on the modified couple stress theory. Compared to previous work, this newly developed nonlinear model can be utilized for predicting the post-instability nonlinear dynamics of fluid-conveying micro-cantilever more than its linear dynamics. By considering the geometric nonlinearities, the gravity, and the effect of loose supports at the downstream end, the nonlinear equation of motion is derived using the Hamilton's principle. The governing partial differential equation is further discretized with the aid of Galerkin's approach. Numerical results show that the fluid-conveying micro-cantilever is capable of displaying rich dynamical behaviors. For a ‘horizontal’ or ‘hanging’ micropipe conveying fluid, it is found that flutter instability occurs at a critical flow velocity, beyond which the micropipe would undergo a limit cycle motion; for a ‘standing’ micropipe with relatively long length, however, both buckling and flutter instabilities could occur. More interesting dynamical behavior has been obtained for a modified micropipe system with loose supports at its tip end. In the presence of nonlinear constraining force resulted from loose supports, construction of bifurcation diagrams with the flow velocity as variable parameter and some corresponding phase-plane portraits have shown that chaotic vibrations do indeed arise, following a sequence oof period-doubling bifurcations. It is also demonstrated that the presence of small length scale can enhance the stability of the micropipe. However, size dependence of the post-flutter responses for the system is not pronounced.

The k -nearest neighbor (kNN) rule is a classical non-parametric classification algorithm in pattern recognition, and has been widely used in many fields due to its simplicity, effectiveness and intuitiveness. However, the classification performance of the kNN algorithm suffers from the choice of a fixed and single value of k for all queries in the search stage and the use of simple majority voting rule in the decision stage. In this paper, we propose a new kNN-based algorithm, called locally adaptive k -nearest neighbor algorithm based on discrimination class (DC-LAKNN). In our method, the role of the second majority class in classification is for the first time considered. Firstly, the discrimination classes at different values of k are selected from the majority class and the second majority class in the k -neighborhood of the query. Then, the adaptive k value and the final classification result are obtained according to the quantity and distribution information on the neighbors in the discrimination classes at each value of k . Extensive experiments on eighteen real-world datasets from UCI (University of California, Irvine) Machine Learning Repository and KEEL (Knowledge Extraction based on Evolutionary Learning) Repository show that the DC-LAKNN algorithm achieves better classification performance compared to standard kNN algorithm and nine other state-of-the-art kNN-based algorithms.

The k-nearest neighbor (KNN) algorithm has been widely used in pattern recognition, regression, outlier detection and other data mining areas. However, it suffers from the large distance computation cost, especially when dealing with big data applications. In this paper, we propose a new fast search (FS) algorithm for exact k-nearest neighbors based on optimal triangle-inequality-based (OTI) check strategy. During the procedure of searching exact k-nearest neighbors for any query, the OTI check strategy can eliminate more redundant distance computations for the instances located in the marginal area of neighboring clusters compared with the original TI check strategy. Considering the large space complexity and extra time complexity of OTI, we also propose an efficient optimal triangle-inequality-based (EOTI) check strategy. The experimental results demonstrate that our proposed two algorithms (OTI and EOTI) achieve the best performance compared with other related KNN fast search algorithms, especially in the case of dealing with high-dimensional datasets.

Engineering critical assessment (ECA) or fitness-for-service (FFS) is a fracture mechanics based approach that is increasingly utilised for assessing the structural integrity of welded steel structures considering various degradation mechanisms which may occur during service. However, if sufficient number of inputs and/or accurate input values are not available, the ECA result is often considered overly conservative and for such cases adds potentially unnecessary obstacles to design and maintenance solutions High strength steels such as S690, S890 and S960 are increasingly used in the offshore and lifting applications, thus to enhance our confidence in using such steels, it is essential to develop better understanding into the relationship between the information from ECA, fracture toughness that can be currently achieved in industry and the required toughness from rules and regulations. This study explores the influence of different variables on critical fracture toughness requirement of S690 steel structures. In addition, the correlation between all the studied variables are investigated to provide quantitative indications of the most important variables in a static ECA process for high strength steel applications. Quantified sensitivity and correlations are obtained for the six studied variables. Industrial fracture toughness data of welded S690 with section thickness up to 160 mm are collected. This provides a snapshot of currently achievable fracture toughens of S690, in comparison with the ECA results and current rules and standards.

Face sketch is the main approach to find suspect in law enforcement, especially in many cases when facial attribute descriptions of suspects by witnesses are available. Face sketch synthesized from facial attribute text can also be used in sketch based face recognition. While most previous work focus on face photo to sketch synthesis, the problem of sketch synthesis with facial attribute text has not been explored yet. The problem is challenging due to two facts: firstly, no database of face attribute text to sketch is available; secondly, it is hard to synthesize high-quality face sketches due to the ambiguity and complexity of text description. In this paper, we propose a face sketch synthesis approach with text using Stagewise-GAN. Our contributions lie in two aspects: 1) we construct the first text to face sketch database. The database, namely Text2Sketch dataset, is annotated with CUFSF dataset of 1194 sketches. For each sketch, an attribute description is labelled; 2) we synthesize vivid face sketches using Stagewise-GAN. We use user study, face retrieval performance with synthesized sketch, and quantitative results for evaluation. Experimental results show the effectiveness of our approach.

Highly efficient and stimulus-responsive nanomedicines for cancer treatment are currently receiving tremendous attention. In this study, an acid-triggered charge-reversible graphene-based all-in-one nanocomplex is appropriately designed by surface modification with multilayer polymers and simultaneous co-transportation of photosensitizer indocyanine green (ICG) and oligonucleotide inhibitor of miR-21 (miR-21i) to achieve highly efficient genetic phototherapy in a controlled manner. The nanocomplex (denoted as GPCP/miR-21i/ICG) effectively protects miR-21i from degradation and exhibits excellent photothermal/photochemical reactive oxygen species (ROS) generation as well as fluorescence imaging ability. The cargoes ICG and miR-21i can significantly be released at acidic pH compared with normal physiological medium and escaped from endosomes/lysosomes due to the acid-triggered charge reversal effect. Typically, the released miR-21i downregulate the endogenous miR-21 and result in the upregulation of the target proteins PTEN and Bax, thus increasing the phototherapeutic efficiency of ICG. High in vivo anticancer efficiency against the MDA-MB-231 triple-negative breast cancer (TNBC) model is obtained due to the combination of genetic regulation of miR-21i and the photokilling effect of ICG. This work highlights the great potential of this smart nanocomplex as an attractive modality of gene-photo combined treatment of cancer, especially for intractable TNBC.

This study concentrates on a comparison between steel plate and stiffened panels subject to localised corrosion. A finite element analysis is used to investigate the effect of random corrosion on the compressive strength capacity of marine structural units. Variables include the extent of corrosion; slenderness ratio and aspect ratio. A corrosion prediction model is incorporated to determine the thickness reduction with time. Corrosion-induced volume loss results in a greater reduction of ultimate strength for slender plates compared to stiffened panels, up to 45%, showing the structural element selection can strongly influence the accuracy of the estimated corrosion damage effect.

The aim of this paper is to develop a new nonlinear theoretical model for cantilevered microbeams and to explore the nonlinear dynamics based on the modified couple stress theory, taking into account of one single material length scale parameter. The full nonlinear equation of motion, which is valid when the motion is large, is derived using the Hamilton’s principle. The governing partial differential equation is further discretized with the aid of Galerkin’s method. The numerical results, in which the existence of primary resonances of the first mode of the microbeam due to base excitations is demonstrated, are presented in the form of frequency–response curves, phase portraits and time histories. For a cantilevered microbeam subjected to harmonic base excitations, it is found that the frequency–response curve exhibits a clear softening-type behavior. For the same system but with an intermediate linear spring support, it is shown that the linear spring is capable of increasing the resonance frequency and decreasing the resonance amplitudes of the microbeam. Interestingly, it is found that the softening behavior could be changed to a hardening one if an intermediate nonlinear spring is added somewhere along the microbeam’s length.

An approach to simulate the behaviour of steel stiffened plates subjected to weld-induced grooving corrosion using nonlinear finite element modelling is proposed. The model includes the effects of different initial geometric imperfections and weld-induced residual stresses. The influence of corrosion damage on the load shortening curves and ultimate strength is investigated. It is shown that grooving corrosion depth has a greater influence on structural performance as compared with corrosion width for the same volume loss. Such corrosion damage could cause a significant reduction in the ultimate strength of a plate panel. Considerations of weld-induced deflection and residual stresses further enhance the corrosion influence on the strength capacity.

In this paper, the nonlinear dynamics of a cantilevered pipe conveying fluid interacting with two support walls on both sides is first investigated. The main goal of this study is to explore how the dynamics of a cantilevered pipe will perform in the presence of two support walls along the pipe axis. The interacting force is defined as impact in order to simulate the impacting effects for a pipe with various flow velocities. The impact force is modeled either by a cubic spring or by a trilinear spring. The nonlinear equations of motion are discretized via Galerkin’s method, and the discretized equations are solved by using a fourth-order Runge–Kutta method. Results show that the pipe would periodically impact the walls when the flow velocity is just beyond the critical value. When the flow velocity is sufficiently higher, however, the pipe may behave different patterns of contacting the walls, such as point contact and segments contact. Periodic, quasi-periodic motions, as well as chaotic oscillations are observed in such a pipe system.

Zhundong coalfield is one of the superhuge coalfields newly discovered in Xinjiang Autonomous Region of China. While many studies on alkali metals in coal/biomass have been reported previously, few efforts were conducted on Zhundong coals which are characterized by a high content of sodium. It is challenging to explore the ash deposition problems related to Zhundong coals directly using existing findings on the behavior of alkali metals. The occurrence mode and transformation of alkali metals during thermal conversion of Zhundong coals could be quite different. Specific investigation on sodium transformation during pyrolysis of Zhundong coals will make a contribution to our understanding on the fate and behavior of alkali metals involved in high-sodium coals. Here, the release and transformation fundamentals of sodium during pyrolysis of two Zhundong bituminous coals were investigated using an experimental approach of sequential chemical extraction. The sodium volatilization and evolution of occurrence mo...

This paper develops and analyzes a theoretical model for flexural vibrations of microbeams in flow with clamped–clamped ends. Based on a modified couple stress theory and the Hamilton’s principle, the governing equations for three-dimensional vibration of a curved microbeam are derived with the consideration of the fluid force induced by external flow. Meanwhile, as a special case, the reduced equation for a straight microbeam in flow is obtained. This new theoretical model contains a material length scale parameter that can capture the size effect. The differential quadrature method (DQM) is introduced to formulate the discrete forms of the governing equations. Based on the numerical calculations, the effects of several system parameters, i.e. the open angle, the characteristic size of the microbeam and the flow velocity, on the natural frequencies and stability of the system are discussed. The results show that, with a sufficiently high flow velocity, the static buckling instability may occur for both curved and straight microbeams in flow, which should be considered in the design and applications. Furthermore, the size effect on the vibration properties is significant when the characteristic size of the microbeam is comparable to the internal material length scale parameter.

Background Most patients with chronic kidney disease (CKD) fail to achieve blood pressure (BP) management as recommended. Meanwhile, the effects of promising intervention and telehealth on BP control in CKD patients remain unclear. We aimed to evaluate the efficacy of telehealth for BP in CKD non-dialysis patients. Methods Databases including MEDLINE, EMBASE, CENTRAL, CNKI, Wanfang, VIP and CBM were systematically searched for randomised controlled trials or quasi-randomised controlled trials on telehealth for BP control of CKD3-5 non-dialysis patients. We analysed systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), serum creatinine, and estimated glomerular filtration rate (eGFR) with a fixed-effects model. Results Three studies, with total 680 subjects, were included in our systematic review and two were included for meta-analysis. Pooled estimates showed decreased SBP (pooled mean difference (MD), −5.10; 95% confidence interval (CI), −11.34, 1.14; p > 0.05, p = 0.11), increased DBP (pooled MD, 0.45; 95% CI, −4.24, 5.13; p > 0.05, p = 0.85), decreased serum creatinine (pooled MD, −0.38; 95% CI, −0.83, 0.07; p > 0.05, p = 0.10) and maintained eGFR (pooled MD, 4.72; 95% CI, −1.85, 11.29; p > 0.05, p = 0.16) in the telehealth group. There was no significant difference from the control group. MAP (MD, 0.6; 95% CI, −6.61, 7.81; p > 0.05, p = 0.87) and BP control rate ( p > 0.05, p = 0.8), respectively, shown in two studies also demonstrated no statistical significance in the telehealth group. Conclusions There was no statistically significant evidence to support the superiority of telehealth for BP management in CKD patients. This suggests further studies with improved study design and optimised intervention are needed in the future.

In order to reduce the influence of scattering and absorption on tissue fluorescence spectra, after tissue fluorescence and diffuse reflectance in different tissue optical properties were simulated by the Monte Carlo method, a tissue intrinsic fluorescence recovering algorithm making use of diffuse reflectance spectrum was developed. The empirical parameters in the tissue intrinsic fluorescence recovering algorithm were coded as a particle in the solution domain, the classification performance was defined as the fitness, and then a particle swarm optimization (PSO) algorithm was established for empirical parameters optimization. The skin autofluorescence and diffuse reflectance spectra of 327 subjects were collected in Anhui Provincial Hospital. The skin intrinsic autofluorescence spectra were recovered by using the empirical approach and the integration area of the spectra were calculated as fluorescence intensity. Receiver operating characteristic (ROC) analysis for fluorescence intensity was applied to evaluate the classification performance in type 2 diabetes screening. In addition, a support vector machine (SVM) method was implemented to improve the performance of the classification. The results showed that the sensitivity and specificity were 32% and 76% respectively, and the area under the curve was 0.54 before recovering, while the sensitivity and specificity were 72% and 86% respectively, and the area under the curve was 0.86 after recovering. Furthermore, the sensitivity and specificity increased to 83% and 86% respectively when using linear SVM while 84% and 88%, respectively, when using nonlinear SVM. The results indicate that using the tissue fluorescence spectrum recovery algorithm based on PSO can improve the application of tissue fluorescence spectroscopy effectively.

For marine platforms, assessing the structural resilience in a corroded condition is vital for both design and maintenance practices. With the development of computational and experimental methods for structural analysis, the accuracy of the structural response prediction relies on a better understanding of the material degradation process. However, a realistic estimate of corrosion is inherently a complex undertaking. Corrosion of even a single form can often involve multiple stages, each of which has different steps across several geometric scales; corrosion systems are often multi-layered and involve geometric complexities; the mechanical factors (stress/strain distributions) could affect the corrosion initiation and kinetics. These complexities have resulted in scientific barriers to the advancement of a corrosion prognosis that forecasts damage accumulation, as well as a computational realization of the corrosion-structural analysis. This paper reviews the numerical and experimental work that the authors have done, including the development of nonlinear finite element models to assess the behavior of damaged steel ship structures, full-field experimental verifications, application of the mechano-electrochemical theory and in situ tensile-corrosion tests. It is intended that the outcome of this research will be the establishment of a systematic multi-scale multi-physics experimental and numerical protocol for predicting aged structural resilience.

Skin cholesterol is a novel biomarker to assess the risk of atherosclerotic diseases. To detect skin cholesterol noninvasively and rapidly, a system was designed based on the diffuse reflectance spectroscopy. The feasibility of this system was validated through detecting cholesterol of pig skin samples, and skin cholesterol in vivo of subjects. The experimental results showed that, diffuse reflectance absorbance integrated intensity S measured the concentration of cholesterol in the pig skin samples quantitatively. After adjusting for age, gender and other factors, it showed a significant positive correlation between S of subjects and the total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) which were the main risk factors for atherosclerotic diseases with the correlation coefficients 0.860(P

In this paper, a nonlinear theoretical model for three-dimensional vibration analysis of curved microtubes conveying fluid with clamped–clamped ends is developed and analyzed based on a modified couple stress theory and the Hamilton’s principle. This new theoretical model contains a material length scale parameter that can capture the size effect. In-plane and out-of-plane bending motions, axial motion and twist angle of the microtube are considered in the proposed model. The Lagrange nonlinear axial strain is adopted to obtain the static deformation induced by internal fluid flow. The derived equations of motion are discretized through the Galerkin method. Linearized equations around the static deformation are obtained from the discretized equations, and then the evolution of in-plane and out-of-plane natural frequencies for the curved microtube with various values of flow velocity and material length scale parameter is investigated. The results show that size effect on the vibration properties is significant when the characteristic size of the microtube is comparable to the internal material length scale parameter, and no instabilities are possible for curved microtubes if the nonlinear axial deformation is considered. Therefore, both the size effect and the axial nonlinearity have to be incorporated in the design of curved microscale beam/tube devices and systems.

IEEE 802.11 is an economical and efficient standard that has been applied to vehicular networks. However, the long handoff latency of the standard handoff scheme for IEEE 802.11 has become an important issue for seamless roaming in vehicular environments, because more handoffs may be triggered due to the higher mobility of vehicles. This paper presents a new and fast location-based handoff scheme particularly designed for vehicular environments. With the position and movement direction of a vehicle and the location information of the surrounding access points (APs), our protocol is able to accurately predict several APs that the vehicle may possibly visit in the future and to assign these APs different priority levels. APs on higher priority levels will be scanned first. A blacklist scheme is also used to exclude those APs that showed no response to the scanning during previous handoffs. Thus, time spent on scanning APs is supposed to be significantly reduced. The simulation results show that the proposed scheme attains not only a lower prediction error rate but also lower link layer handoff latency and that it has a smaller influence on jitter and throughput. Moreover, these results show that the proposed scheme has a smaller total number of handoffs than other handoff schemes.

The state-of-the-art in modelling the influence of corrosion damage on the ultimate strength of aged steel-plated maritime platforms is reviewed. This critical review outlines the corrosion mechanisms and fundamentals of steel-plated structures in the marine environment. Recent developments in mathematical modelling strategies, in association with in situ thickness measurements, have significantly enhanced the qualitative understanding of the corrosion processes at various locations within marine structures. Based on the corrosion prediction, both experimental and numerical methods have been adopted to realistically assess the ultimate strength of such corroded steel ship structures, in order to ultimately improve the survey and repair strategies.

Purpose The rate of litter decomposition can be affected by a suite of factors, including the diversity of litter type in the environment. The effect of mixing different litter types on decomposition rates is increasingly being studied but is still poorly understood. We investigated the effect of mixing either litter material with high nitrogen (N) and phosphorus (P) concentrations or those with low N and P concentrations on litter decomposition and nutrient release in the context of agroforestry systems.

A numerical methodology is established to study the mechano-electrochemical performance of corroded steel structures under external and internal stresses. Results show that mechanical stimuli (elastic/plastic deformation) increase the local anodic current density, and thus the corrosion behavior dynamically responds to the loading conditions. The current density increment for a multi-component stress system is largely dependent on both hydrostatic pressure and equivalent plastic strain. Moreover, the mechano-electrochemical corrosion is more affected by plastic deformation, resulting in localized areas being more anodic. Existing corrosion introduces extra stress/strain concentration, which further reduces the structural strength capacity and intensifies the corrosion damage.

Hydrodynamic calculation and safety evaluation are considered to be a key technology in the design of the water-cooled wall of double-reheat boilers. The accuracy of the assumed heat flux distribution directly affects the accuracy of these hydrodynamic calculations. In the present work, an in-house code was coupled with combustion simulation to study the hydrodynamic characteristics of the water-cooled wall of a 1000 MW USC double-reheat boiler equipped with deep air-staging and flue gas recirculation. The heat flux distribution used in these calculations was obtained from the standard thermal deflection coefficient curve and from combustion simulation results. The calculation results of the outlet temperature of the water-cooled wall were then compared with in-situ experimental data. The results illustrate that the calculated temperature of the outlet of water-cooled wall based on the heat flux distribution obtained by combustion simulation agrees well with the actual operating conditions of the boiler. Conversely, large deviation was caused when the standard heat flux distribution curve was adopted. The present work demonstrates that combustion simulation coupled with hydrodynamics can be effectively used for design new types of boilers.

In this study, the forced vibration of a curved pipe conveying fluid resting on a nonlinear elastic foundation is considered. The governing equations for the pipe system are formed with the consideration of viscoelastic material, nonlinearity of foundation, external excitation, and extensibility of centre line. Equations governing the in-plane vibration are solved first by the Galerkin method to obtain the static in-plane equilibrium configuration. The out-of-plane vibration is simplified into a constant coefficient gyroscopic system. Subsequently, the method of multiple scales (MMS) is developed to investigate external first and second primary resonances of the out-of-plane vibration in the presence of three-to-one internal resonance between the first two modes. Modulation equations are formed to obtain the steady state solutions. A parametric study is carried out for the first primary resonance. The effects of damping, nonlinear stiffness of the foundation, internal resonance detuning parameter, and the magnitude of the external excitation are investigated through frequency response curves and force response curves. The characteristics of the single mode response and the relationship between single and two mode steady state solutions are revealed for the second primary resonance. The stability analysis is carried out for these plots. Finally, the approximately analytical results are confirmed by the numerical integrations.

Software-intensive system has been the major form of the current software system, and therefore, the reliability evaluation of Software-intensive system is becoming constantly more important. Since the black-box model is not suitable because of the large scale and heterogenicity of the embedded system, the architecture-based approach is proposed to analyze the reliability of large and Software-intensive systems. However, most of the contemporary architecture-based software reliability analysis approaches assume that a component failure leads to a system failure that is restrictive because of the fault propagation and tolerance mechanism in the Software-intensive system. This paper presents an approach based on absorbing discrete time Markov chains (DTMCs) model to evaluate the reliability of Software-intensive system considering the fault propagation and tolerance mechanism, within the context of the system architecture. This approach considers the system fault tolerance ability as the criterion reflecting the reliability of Software-intensive system, also it proposes the fault pervasion intensity to quantify the difficulty and scope of the fault propagation through the edge between two components and the fault tolerance rate to quantify the probability of the correct output when the input of the component is incorrect. We check the value of the approach using a case study. From the case study, we can draw some conclusions: a) Because of the evaluation in earlier stage, the reliability evaluation approach based on architecture is not really accurate b) By contrast, the approach we proposed which considers fault propagation is more accurately than the approach which assumes the reliabilities of the modules are independent.

The use of ventilation air methane (VAM) has attracted more and more attention in recent years. The experimental investigation on homogeneous combustion of fuel ultra-lean methane–air mixtures is carried out in reactors packed with and without a monolith. The experimental results show that the methane oxidation follows a consecutive reaction scheme. In the reaction process, although a little CH4 may be directly oxidized to CO2 at low temperatures, most CH4 is oxidized to CO as the intermediate product and then further oxidized to CO2 at high temperatures. The present experimental results also show that the presence of a monolith has an obvious effect on the combustion of methane. The methane combustion can be enhanced by both expanding the specific surface area and decreasing the diameter of the monolith channel. However, an extremely small diameter may lead to the quenching of combustion. Moreover, it is found that the effect of homogeneous combustion cannot be neglected for the catalytic flow reversal r...

This paper describes an experimental study on the catalytic combustion of ventilation air methane in a vertical reactor. The mixture of natural gas and compressed air was used in the experiments, and the combustion products were analyzed by the Fourier transform infrared (FTIR) gas analyzer. The effects of the initial temperature, cycle time, feed gas concentration, and space velocity were studied. The experimental results show that the reactor could run under a wide range of operating conditions with self-sustaining operation and high methane conversion. Besides, it could even run with a feed gas concentration as low as 0.13 vol % without generation of CO and NOx, which has not been achieved in previous studies. The optimization of operating parameter combination increases the stability and efficiency of combustion. Different from the previous studies, the present research shows that the temperature profile of the cyclic steady state is not affected by the initial temperature. In addition, the methane co...

Many phenomenological models of cerebral aneurysm formation have been proposed. Such studies have focused on modeling the structural adaption of the arterial wall. However, further development is required to accurately represent the underlying mechanobiology during growth and remodeling processes. Here, we present a 3D computational model that incorporates transmurally heterogeneous material concentrations. This is a critical step toward more realistic models for growth and adaptation. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)

Embedded software system has been the major form of the current software system, and therefore, the reliability evaluation of embedded software system is becoming constantly more important. Since the black-box model is not suitable because of the large scale and heterogenicity of the embedded system, the architecture-based approach is proposed to analyze the reliability of large and embedded software systems. However, most of the contemporary architecture-based software reliability analysis approaches assume that a component failure leads to a system failure that is restrictive because of the fault propagation and tolerance mechanism in the embedded software system. This paper presents an approach based on absorbing discrete time Markov chains (DTMCs) model to evaluate the reliability of embedded software system considering the fault propagation and tolerance mechanism, within the context of the system architecture. This approach considers the system fault tolerance ability as the criterion reflecting the reliability of embedded software system, also it proposes the fault pervasion intensity to quantify the difficulty and scope of the fault propagation through the edge between two components and the fault tolerance rate to quantify the probability of the correct output when the input of the component is incorrect. We check the value of the approach using a case study.

"Feel & See the Globe" is a thermal, interactive installation. The central idea is to map temperature information in regions around the world from prehistoric, modern to futuristic times onto a low fidelity display. The display visually communicates global temperature rates and lets visitors experience the temperature physically through a tangible, thermal artifact. A pertinent educational aim is to inform and teach about global warming.

In an attempt to elucidate the relationship and underlying processes of metal oxidation under stress, we combined the electrochemical characterisation with Density-Functional-Theory (DFT) calculations to interrogate the (100) surface of copper. The oxidised (100) surface shows a missing-row reconstruction, which is believed to be driven by surface stress. Hence, additional mechanical stimuli might have a significant impact on the onset of Cu oxidation. We find that different surface sites respond differently to strain. Oads at the thermodynamically favoured high-coordination hollow site (O coordinated to four Cu) is stabilised by up to 130 meV by imposing 2% tensile strain onto the surface, while the low-coordination top site (O coordinated to one Cu) shows a markedly different sensitivity. By cramping into the hollow site, Oads induces compressive stress into the (100) surface, an effect that is largely absent for the adsorption at the top site. We also find that the thermodynamic advantage of reconstructive underpotential surface oxidation is diminished under tensile strain. Hence, imposing tensile stress counter-balances the oxygen induced surface stress, which might have an implication on the onset of bulk copper oxidation. Studying Cu(100) single crystal surfaces in perchloric acid using cyclic voltammetry, we were able to confirm sensitivity of the electrochemical response towards the elastic strain.

To compare the clinical efficacy and safety of solifenacin versus tolterodine in patients with overactive bladder (OAB).Literature searches were performed with PubMed, EMBASE, Ovid and Google Scholar databases, Wanfang and CNKI from inception to October 2013 for comparative studies assessing solifenacin and tolterodine for OAB. The data were extracted and evaluated by two reviewers independently according to the Cochrane Handbook for Systematic Reviews. Meta-analyses were conducted with RevMan 5.2.A total of 7 studies involving 1 805 patients were retrieved. Compared with tolterodine immediate release (IR), the number of urgency episodes and urge incontinence episodes in 24 h and the rate of dry mouth were significantly lower in patients on solifenacin (RR = -0.34, 95% CI: -0.50--0.18, P = 0.00; RR = -0.29, 95% CI:-0.55--0.04, P = 0.03; RR = 0.58, 95% CI: 0.41-0.83, P = 0.00) and the rate of constipation was higher in those on solifenacin (RR = 2.72, 95% CI: 1.38-5.39, P = 0.00). No significant differences existed between tolterodine IR and solifenacin in mean micturition volume per voiding and micturitions episodes in 24 h (P = 0.05,0.08). Between solifenacin and tolterodine extended release (ER), the number of urgency episodes, micturition and urge incontinence episodes in 24 h and mean micturition volume per voiding were not statistically different (all P0.05). The incidence of major adverse events, such as dry mouth, constipation and blurred vision, was not significantly different (all P0.05). And most adverse events were mild.Solifenacin is superior to tolterodine IR in treating OAB symptoms. However the rate of constipation is higher for solifenacin. Both solifenacin and tolterodine ER have similar therapeutic efficacies and adverse events.

This work has developed numerical models simulating steel plate corrosion degradation and presents a series of novel finite element modeling to assess the influence of localized pit distribution and bench-shaped pits, which are often observed in long-term exposures. Four location patterns of one-sided corroded shipping steel plates have been considered, which include both geometric and material non-linearities. Validation of the modeling method is achieved by a thermoelastic stress analysis, which provides the principal stress distribution over the plate surface. The modeling results demonstrate that the frequently detected localized corrosion may reduce the ultimate strength by up to 20% compared to uniformly corroded plate. In addition, bench-shaped pits may further decrease the ultimate strength by up to 14% compared to the no-bench condition with the same degree of pitting.

To compare the clinical effectiveness and safety of alpha-blocker alone and combined tamsulosin with an anticholinergic drug for bladder outlet obstruction (BOO) with overactive bladder (OAB).Literature search was performed using PubMed, EMBASE, Ovid, Wanfang, and CNKI from inception to October 2013 for comparative studies assessing alpha-blocker alone and combined alpha-blocker with an anticholinergic drug for BOO+OAB. Data were extracted and evaluated by two reviewers independently according to the Cochrane Handbook for systematic reviews. Meta-analyses were conducted using RevMan 5.2.A total of 7 studies involving 3 458 patients were included for the analysis. The values of total IPSS and storage IPSS reduced significantly after treatment in combination group (RR = -0.23, 95%CI: -0.44--0.02, P = 0.03; RR = -0.69, 95%CI: -0.88--0.51, P0.01). There were no significant differences between the two groups in voiding IPSS and Qmax (P = 0.86 and 0.89). The incidences of dry mouth (OR = 2.53), constipation (OR = 3.74), dizziness (OR = 0.73), and urinary retention (OR = 0.26) were higher in combination group than in alpha-blocker alone group (P0.05). But most adverse events were mild in degree.Alpha-blocker combined with an anticholinergic drug in the treatment of BOO+OAB was better than that of alpha-blocker alone, and was safe and well tolerated.

The origin of tiny neutrino masses and the baryon number asymmetry of the Universe are naturally interpreted by the canonical seesaw and leptogenesis mechanisms, in which there are the heavy Majorana neutrino mass matrix M-R, the Dirac neutrino mass matrix M-D, the charged-lepton mass matrix M-l, and the effective (light) neutrino mass matrix M-nu. We find that Im(det[(MDMD)-M-dagger, (MRMR)-M-dagger]), Im(det[MlMl dagger, M nu M nu dagger]), and Im(det[MlMl dagger, MDMD dagger]) can serve as a basis-independent measure of CP violation associated with lepton-number-violating decays of heavy neutrinos, flavor oscillations of light neutrinos, and lepton-flavor-violating decays of charged leptons, respectively. We first calculate these quantities with the help of a standard parametrization of the 6 x 6 flavor mixing matrix, then discuss their implications on both leptogenesis and CP violation at low energy scales. A comparison is also made with the weak-basis invariants of leptogenesis, as proposed by Branco et al.

The tongue is made up of a collection of interwoven families of muscle fibres, but little is known about the function of each of these muscle groups during physiological motions of the tongue. Magnetic resonance imaging (MRI) tissue tagging has been used to observe internal tongue tissue deformation, and estimate possible contractile patterns of the tongue muscles. However, the complex fibrous arrangement and the limited field of view from 2D planar images make it difficult to identify muscle movements in 3D space. This casts doubt on the empirical conclusions drawn from these studies. Here we present a computational modelling framework to estimate the contractile properties of the different muscle groups in the tongue by combining a generic tongue model with anatomical and strain data derived from tagged MR images. Tongue propulsion during dry swallowing was simulated and results were compared with previously published data. The model predicated model results by using empirical conclusion showed that, the co-activation of single intrinsic muscles (transversus, verticalis) cannot explain the most dominate expansion in the posterior tongue body. Contact between the tongue and upper palate and simultaneous contraction with more muscles may also result in anterior–posterior expansion.