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With Me3NO being present, the ligand substitution reaction of [ (μ-dmedt){Fe (CO)3}2] by 4,4′-bipyridine afforded a new diiron complex (μ-dmedt)Fe2 (CO)5 (4,4′-bipyridine) 1, which was detected using IR, 1H NMR, elemental and MS analyses. Our electrochemical tests showed that compound 1 is capable to catalyze hydrogen production, which served as an efficient molecular electro-catalyst in the CH3CN solution or adsorbed on the surface of electrode for electrochemical generation of molecular hydrogen from HOAc or aqueous media. The relevance of these studies for designing efficient hydrogenase models lies in providing insights into the core of stereo-electronic features. A novel complex (μ-dmedt)Fe2 (CO)5 (4,4′-bipyridine) 1 bearing a functional groups have been prepared, which served as an efficient molecular electro-catalyst in the CH3CN solution or chemisorbed on the surface of electrode for electrochemical generation of molecular hydrogen from HOAC or aqueous media. Those will be of relevance to the natural system and crucial to the potential industrial application.

The molecular mechanism by which silica nanoparticles (SiNPs) cause cellular apoptosis in the respiratory system is unclear. Silent mating type information regulation 2 homolog 1 (SIRT1), an NAD+-dependent deacetylase, mediates the pulmonary damage associated with several environmental stimuli. However, the SIRT1 response to SiNP exposure and its role in SiNP-triggered pulmonary toxicity remains unknown. Here, SiNPs were found to downregulate nuclear rather than cytosolic SIRT1 protein levels in human bronchial epithelial cells (BEAS-2b). They did not affect SIRT1 gene expression but accelerated SIRT1 protein degradation via c-Jun N-terminal kinase (JNK) activation. SiNP-mediated SIRT1 suppression markedly increased tumour protein 53 (p53) acetylation and cytoplasmic localisation, leading to the release of cytochrome c from mitochondria to the cytosol. SIRT1 overexpression dramatically decreased p53 acetylation and its cytoplasmic localisation, and this was accompanied by attenuated apoptosis in SiNP-exposed cells. Finally, SiNPs suppressed SIRT1 and stimulated apoptosis in the lung tissues of mice. In summary, SiNPs downregulate nuclear SIRT1 via JNK activation-mediated protein degradation, which leads to apoptosis via p53 acetylation and cytoplasmic localisation. These findings improve our understanding of SiNP-induced pulmonary damage and molecular targets to antagonise it.

Effective treatment of 2,4-dichlorophenol (2,4-DCP) in wastewater is essential, as it could pose great threat to the environment. A hydrothermal biochar (hydrochar) was used to assist the electrochemical oxidation treatment of 2,4-DCP. The removal of 2,4-DCP using hydrochar in anode and cathode area with and without proton exchange membrane (PEM) under 3–9 V of electrolysis was investigated. Enhanced 2,4-DCP degradation in the anode area was achieved compared with the adsorption or electrolysis alone. The highest 2,4-DCP removal (∼76%) was obtained using the hydrochar in the anode area with PEM under 9 V. The mechanism for the 2,4-DCP removal during the electrolysis included adsorption by hydrochar and electrochemical degradation by the reactive oxygen species (ROS) generated by the electrode as well as the persistent free radicals (PFR) on hydrochar. The OH produced from anode was the predominant ROS contributing to the 2,4-DCP degradation under 9 V of electrolysis.

Polycyclic aromatic hydrocarbons (PAHs) are environmental endocrine disruptors, which may modify the bone mineralization. However, epidemiological evidences on this issue were scant. We aimed to investigate the associations of PAHs with bone mass density (BMD) and osteoporosis based on a nationally-representative sample from general U.S.Data utilized were extracted from the 2005-2010 National Health and Nutrition Examination Survey (NHANES). Nine urinary PAHs (U-PAHs) metabolites were measured as exposure biomarkers. Associations of specific U-PAHs with BMD and osteoporosis were estimated by multivariable adjusted linear regression models and logistic regression models, respectively. Compared with women at the first tertiles, those at the third tertiles of 1-Hydroxynapthalene, 2-Hydroxyfluorene, 3-Hydroxyphenanthrene, 2-Hydroxyphenanthrene and 9-Hydroxyfluorene had significantly decreased BMD levels [coefficient (β) = -0.023 to -0.014, p 0.05] or increased likelihoods of osteoporosis [odds ratios (ORs) = 1.86 to 3.36, p 0.05] at different bone sites. Whereas, elevated BMD levels (β = 0.021, p 0.05) at trochanter and decreased likelihoods of osteoporosis (OR = 0.33, p 0.05) at intertrochanter were observed among women at the second tertiles of 1-Hydroxypyrene and 2-Hydroxynapthalene, respectively. Similar results were found for all the population, i.e., combination of men and women. Most of the significant associations disappeared among adult men only. Furthermore, Associations between U-PAHs and BMD were stronger for postmenopausal women when compared with premenopausal group. In conclusion, associations of U-PAHs with BMD and osteoporosis varied by specific U-PAHs and bone sites, as well as menopausal status and genders in U.S. adults.

Background While much literature reported the access of Chinese older migrants to health services, little was known about the differences among sub-groups of older adults, including urban-to-urban and rural-to-urban migrants, and urban and rural permanent residents. This study aimed to examine the access of these four groups to health services in Zhejiang Province, China and provide an evidence for the development of health services policies. Methods A cross-sectional survey was conducted in community-dwelling older adults (aged 60 years or above) in 2013. Participants were recruited by random sampling. Demographic information and access to health services for the elderly populations were obtained via interviews using a self-designed structured questionnaire. Pearson’s chi-square tests and Cochran-Mantel-Haenszel (CMH) tests were performed to examine the differences in access to health services among the four groups. Binary logistic regression was conducted to explore the associations of participants’ visits to doctors with their group status after controlling confounding factors. Results The two-week hospital visiting rates were significantly lower in migrants (55.56% in rural-to-urban and 62.50% in urban-to-urban) than that in urban and rural permanent residents (67.40 and 82.25%, respectively; p

Sedimentation velocity experiments performed in the analytical ultracentrifuge are modeled using finite element solutions of the Lamm equation. During modeling, three fundamental parameters are optimized: the sedimentation coefficients, the diffusion coefficients, and the partial concentrations of all solutes present in a mixture. A general modeling approach consists of fitting the partial concentrations of solutes defined in a two-dimensional grid of sedimentation and diffusion coefficient combinations that cover the range of possible solutes for a given mixture. An increasing number of grid points increases the resolution of the model produced by the subsequent analysis, with denser grids giving rise to a very large system of equations. Here we evaluate the efficiency and resolution of several regular grids and show that traditionally defined grids tend to provide inadequate coverage in one region of the grid, while at the same time being computationally wasteful in other sections of the grid. We describe a rapid and systematic approach for generating efficient two-dimensional analysis grids that balance optimal information content and model resolution for a given signal-to-noise ratio with improved calculation efficiency. These findings are general and apply to one- and two-dimensional grids, although they no longer represent regular grids. We provide a recipe for an improved grid point spacing in both directions which eliminates unnecessary points, while at the same time providing a more uniform resolution that can be scaled based on the stochastic noise in the experimental data.

Air pollution is one of the leading preventable threats to public health. Emerging evidence indicates that exposure to environmental stressors is associated with abnormal foetal development. However, how prenatal exposure to diesel exhaust PM

Background Many studies focused on health inequality between migrant older adults and local older adults, while few study concerned the health inequalities between urban-to-urban and rural-to-urban migrant older adults. This study aimed to compare physical health and mental health between these two groups in Hangzhou, Zhejiang Province, China, and to explore the relationship between cognitive social capital, social integration and health among migrant older adults. Methods A two-stage stratified sampling method was employed to recruit participants from May to August 2013 in Hangzhou. Measurement data were compared with student’s t-tests and multivariate analysis of variance (MANOVA). Multiple linear regression was adopted in this study. Results A total of 1000 of participants who met the inclusion criteria were analyzed, consisting of 527 (52.7%) urban-to-urban and 473 (47.3%) rural-to-urban migrant older adults. There were no statistically significant difference in physical health and mental health between urban-to-urban and rural-to-urban groups on the whole. However, urban-to-urban migrant older adults had a higher reciprocity and social integration than did in rural-to-urban group (13.36 vs. 12.50, p p p p p p p p Conclusions Social capital and social integration were played important roles in health of migrant older adults. The female rural-to-urban migrant older adults, those aged over 70 years, and older adults who were not in marriage should be especially concerned in health policy making.

Background Acrylamide-induced immunotoxicity and allergic dermatitis have been reported in animal experiments and clinical reports, respectively. However, epidemiological evidence from the general population is limited. Objectives The purpose of the present study was to estimate the associations between acrylamide exposure and allergy-related outcomes in the general US population. Methods A total of 6982 subjects were selected from the National Health and Nutrition Examination Survey 2005–2006 (NHANES). Internal exposure was measured by the hemoglobin adducts of acrylamide (HbAA) and its metabolite glycidamide (HbGA). Allergy-related outcomes including asthma, hay fever, allergy, itchy rash, sneeze, wheeze and eczema were obtained by self-administered questionnaires. Allergic sensitization was assessed by the total immunoglobulin E (IgE) levels. The associations of HbAA and HbGA quartiles with allergy-related outcomes were calculated using logistic regression models with multivariable adjustments. Analyses were additionally stratified according to age, gender and serum cotinine levels. Results When setting quartile 1 of HbAA as reference, the odds ratios (ORs) [95% confidence intervals (CIs)] of quartile 2 to 4 for eczema were 1.18 (0.79–1.76), 1.14 (0.73–1.78) and 1.58 (1.14–2.18), respectively ( p trend = 0.002). Individuals at the highest quartile of HbGA had significantly elevated likelihoods of itchy rash (OR = 1.37, 95% CI = 1.02–1.83, p trend = 0.032) and eczema (OR = 1.45, 95% CI = 1.06–1.97, p trend = 0.044). The stratification analyses indicated various results in different subgroups. Conclusions This study indicated significant associations between HbAA and HbGA levels and the likelihoods of allergy-related outcomes in the general US population, depending on age, gender and smoke exposure status. These findings suggested potential public health concerns for the widespread exposure to acrylamide.

For the linear finite element method based on general unstructured anisotropic meshes in two dimensions, we establish the superconvergence in energy norm of the finite element solution to the interpolation of the exact solution for elliptic problems. We also prove the superconvergence of the postprocessing process based on the global L 2 L^2 -projection of the gradient of the finite element solution. Our basic assumptions are: (i) the mesh is quasi-uniform under a Riemannian metric and (ii) each adjacent element pair forms an approximate (anisotropic) parallelogram. The analysis follows the same methodology developed by Bank and Xu in 2003 for the case of quasi-uniform meshes, and the results can be considered as an extension of their conclusion to the adaptive anisotropic meshes. Numerical examples involving both internal and boundary layers are presented in support of the theoretical analysis.

Air pollution is one of the leading preventable threats to public health. Emerging evidence indicates that exposure to environmental stressors is associated with abnormal foetal development. However, how prenatal exposure to diesel exhaust PM2.5 (DEP) predisposes adult offspring to the development of non-alcoholic fatty liver disease (NAFLD) remains unclear. To examine this, C57BL/6J mice were exposed to DEP or a vehicle before conception and during pregnancy and fed normal chow or a high-fat diet. Then, the hepatic fatty accumulation in the adult male offspring and possible molecular mechanisms were assessed. Our data showed that prenatal exposure to DEP on normal chow led to hepatic steatosis in adult male offspring with normal liver function. However, prenatal DEP exposure relieved the hepatic steatosis and liver function in offspring of mice fed a high-fat diet. Furthermore, prenatal exposure to DEP on normal chow increased lipogenesis and worsened fatty acid oxidation. The counteractive effect of prenatal DEP exposure on high-fat-diet-induced hepatic steatosis was produced through upregulated adenosine 5'-monophosphate-activated protein kinase, and this improved lipogenesis and fatty acid oxidation. Collectively, prenatal exposure to DEP programmed the development of NAFLD differently in the adult male offspring of mice fed normal chow and a high-fat diet, showing the pleotrophic effects of exposure to adverse environmental factors in early life.

We describe an extension of the adaptive space-time finite element method (ASTFEM) used in the solution of the Lamm equation to the case of multicomponent reacting systems. We use an operator splitting technique to decouple the sedimentation-diffusion process from the reaction process. The former is solved with an ASTFEM approach based on the Petrov-Galerkin method and on adaptive moving grids, and the latter is solved with the implicit midpoint Euler's method. Our solution can effectively eliminate the sedimentation errors for each component or species involved in the reaction, and it is free from oscillation near the cell bottom. It offers second-order accuracy, and guarantees conservation of mass without any additional postprocessing, and it permits modeling of multicomponent, equilibrating systems where the reaction rate can be kinetically controlled between an instantaneous reaction and a noninteracting mixture. The proposed ASTFEM solution provides improved efficiency and accuracy compared to classical approaches, especially when medium-sized and large molecules are modeled.

Analytical ultracentrifugation experiments can be accurately modeled with the Lamm equation to obtain sedimentation and diffusion coefficients of the solute. Existing finite element methods for such models can cause artifactual oscillations in the solution close to the endpoints of the concentration gradient, or fail altogether, especially for cases where somega(2)/D is large. Such failures can currently only be overcome by an increase in the density of the grid points throughout the solution at the expense of increased computational costs. In this article, we present a robust, highly accurate and computationally efficient solution of the Lamm equation based on an adaptive space-time finite element method (ASTFEM). Compared to the widely used finite element method by Claverie and the moving hat method by Schuck, our ASTFEM method is not only more accurate but also free from the oscillation around the cell bottom for any somega(2)/D without any increase in computational effort. This method is especially superior for cases where large molecules are sedimented at faster rotor speeds, during which sedimentation resolution is highest. We describe the derivation and grid generation for the ASTFEM method, and present a quantitative comparison between this method and the existing solutions.

Optimal p-interpolation error estimate is derived for the local, projection-based interpolation for H1-conforming elements in three space dimensions. Two different procedures leading to the same logarithmic term ln3/2 p in the estimate, are discussed.

A preconditioning algorithm is developed in this paper for the iterative solution of the linear system of equations resulting from the p-version boundary element approximation of the three dimensional integral equation with hypersingular operators. The preconditioner is derived by first making the nodal and side basis functions locally orthogonal to the element internal bases, and then by decoupling the nodal and side bases from the internal bases. Its implementation consists of solving a global problem on the wire- basket and a series of local problems defined on a single element. Moreover, the condition number of the preconditioned system is shown to be of order O((1 + ln p) 7 ). This technique can be applied to discretization with triangular elements and with general basis functions.

A variety of approaches for generating moving adaptive methods are summarized and compared. They basically fall into two groups: the velocity and the location based methods. The features, including the advantage and weakness, of each group are addressed. Brief numerical results are presented for several commonly used approaches to highlight their features and performance.

In this paper, we consider the numerical solution of time-dependent PDEs using a finite element method based upon rh-adaptivity. An adaptive horizontal method of lines strategy equipped with a posteriori error estimates to control the discretization through variable time steps and spatial grid adaptations is used. Our approach combines an r-refinement method based upon solving so-called moving mesh PDEs with h-refinement. Numerical results are presented to demonstrate the capabilities and benefits of combining mesh movement and local refinement.

In this paper, we propose to modify a preconditioner developed in Pavarino and Widlund (Comput. Math. Appl. 33 (1997) 193) for three-dimensional p-version finite element or spectral element approximations by solving the sub-problems on element faces with an inexact element face solver. Such a modification reduces the cost to evaluate the action of the preconditioner from O(p4) to O(p3) per element face, where p is the polynomial degree used for approximation. Furthermore, it is shown that the coefficient matrix of the inexact solver is spectrally equivalent to the original stiffness matrix on element faces. Therefore, such a change will not affect the polylogarithmic estimate given in Pavarino and Widlund for the condition number of the preconditioned system. Numerical results are also given to confirm the theoretical analysis.

A new adaptive mesh movement strategy is presented, which, unlike many existing moving mesh methods, targets the mesh velocities rather than the mesh coordinates. The mesh velocities are determined in a least squares framework by using the geometric conservation law, specifying a form for the Jacobian determinant of the coordinate transformation defining the mesh, and employing a curl condition. By relating the Jacobian to a monitor function, one is able to directly control the mesh concentration. The geometric conservation law, an identity satisfied by any nonsingular coordinate transformation, is an important tool which has been used for many years in the engineering community to develop cell-volume-preserving finite-volume schemes. It is used here to transform the algebraic expression specifying the Jacobian into an equivalent differential relation which is the key formula for the new mesh movement strategy. It is shown that the resulting method bears a close relation with the Lagrangian method. Advantages of the new approach include the ease of controlling the cell volumes (and therefore mesh adaption) and a theoretical guarantee for existence and nonsingularity of the coordinate transformation. It is shown that the method may suffer from the mesh skewness, a consequence resulting from its close relation with the Lagrangian method. Numerical results are presented to demonstrate various features of the new method.

To study the relationship between social capital and depression among older adults from urban China and the mediating effect of social support on the influence of social capital on depression.Data were collected from face-to-face interviews targeting older adults (N = 928, response rate = 68.1%) aged over 60 years residing in Hangzhou, China, in 2013. Indicators of social capital included both cognitive (trust and reciprocity) and structural (social network and social participation) aspects. The dependent variable depression was measured by the Geriatric Depression Scale, social support was measured by the Multidimensional Scale of Perceived Social Support, and sociodemographic variables (age, education, and household income) and physical function were controlled for analysis. The data were analyzed by factor analysis and a hierarchical regression model.Trust, reciprocity, and social network were significantly associated with geriatric depression after controlling. Social participation was not correlated with geriatric depression. Social support partially mediated the relationships between social capital and geriatric depression.This study provides new evidence that social capital effectively mediates geriatric depression directly and indirectly. The intervention of social capital on depression should therefore consider the two pathways. Future longitudinal studies should help further understand the mechanisms linking social capital and depression.

An r -adaptive finite-element method based on moving-mesh partial differential equations (PDEs) and an error indicator is presented. The error indicator is obtained by applying a technique developed by Bank and Weiser to elliptic equations which result in this case from temporal discretization of the underlying physical PDEs on moving meshes. The construction of the monitor function based on the error indicator is discussed. Numerical results obtained with the current method and the commonly used method based on solution gradients are presented and analyzed for several examples. c ∞ 2001 Academic Press

Error indicators based on solution gradients, interpolation errors, and a posteriori error estimates are presented for use in defining monitor functions for the r-adaptive finite element methods based on moving mesh partial differential equations. The methods are compared with a careful selection of examples. The numerical results show that the methods based on both interpolation errors and a posteriori error estimates work well and have better performance than that based on the solution gradient. Since, the interpolation error is in general easier and more economic to compute than a posteriori error estimates, this study suggests that the error indicator based on interpolation errors be used for the r-adaptive method.

A moving mesh method for structured grids is presented for general solution domains, which are composed of a number of simply shaped blocks. Its basic idea is to solve moving mesh PDEs by overlapping Schwarz iterations and to connect the meshes in each of the blocks smoothly. A finite element method based upon this moving mesh method is developed for solving time dependent PDEs and validated for the problem of laminar flame propagation in an obstacled channel. c © 1999 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 15: 449–467, 1999

We present anr-adaptive finite element method for solving time dependent partial differential equations. A moving mesh partial differential equation, or MMPDE, is used to move the (unstructured) mesh in time. A key to the application of the MMPDE to unstructured mesh movement is to define a computational domain and then compute the corresponding computational mesh as the image of an initial mesh on the given physical domain. The finite element discretization of physical PDEs on moving meshes is addressed. Numerical results are presented to demonstrate the capability of the mesh movement strategy and ther-adaptive finite element method. A fully developedr-adaptive finite element method can be expected to be ideally suited to complement the currently popularh-pfinite element methods and to provide increased reliability and efficiency for mesh adaptation.

In this paper we study the problem of two-dimensional adaptive mesh generation using a variational approach and, specifically, the effect that the monitor function has on the resulting mesh behavior. The basic theoretical tools employed are Green's function for elliptic problems and the eigendecomposition of symmetric positive definite matrices. Based upon this study, a general strategy is suggested for how to choose the monitor function, and numerical results are presented for illustrative purposes. The three-dimensional case is also briefly discussed. It is noted that the strategy used here can be applied to other elliptic mesh generation techniques as well.

In the preconditioned iterative method based on nonoverlapping domain decompositions, the preconditioner is usually of block diagonal type. To calculate its action on a residual vector, it is required to solve a linear system of algebraic equations with the coefficient matrix being the Schur complement block corresponding to the interface. To reduce the computational cost, the Schur complement blocks in the preconditioners can be replaced with other simpler matrices, which are called the interface preconditioners. In this paper, we discuss various interface preconditioners for the p-version finite element method and spectral element method in R2 and R3. Emphases are placed on (1) the lower and upper bounds of the condition numbers for the preconditioned Schur complement blocks using the interface preconditioners, which characterize the enlargement of the overall condition numbers, and (2) the algorithms to efficiently implement the interface preconditioners. Numerical results are presented for the condition numbers using various interface preconditioners.

Domain decomposition method for the h-p version of the finite element method in two and three dimensions are discussed. Using the framework of additive Schwarz method, various iterative methods are described, with their condition numbers estimated. Further, to reduce the cost for solving the sub-problems on element interfaces, different inexact interface solvers are proposed. The effects on the overall condition number, as well as their efficient implementation, are analyzed.

In this paper, we study the additive Schwarz method for the h-p version of the finite element method in three dimensions. The main idea is to treat separately the h-version (linear) components and the p-version (high-order) components by a vertex-based method. It can also be viewed as a three-level method with the level being the linear finite element approximation on the coarse mesh, the linear finite element approximation on the fine mesh, and the high-order finite element approximation on the fine mesh, respectively. The resulting algorithm can be implemented in parallel on the subdomain level for the h-version components and on the element level for the p-version components. The condition number is of order $\max\limits_i(1 + ln Hi pi / hi)2, where Hi stands for the diameter of the subdomain $\Omega_i$, hi is the diameter of the elements in $\Omega_i$, and pi is the maximum of the polynomial degrees used in $\Omega_i$.

Parallel and iterative solvers for large-scale linear system arising from finite element discretization, based on domain decomposition, decompose the approximation spaces into a number of subspaces. The corresponding subproblems are solved in these subspaces, and the solutions are corrected in an iterative process. The subproblems are much smaller in size and much easier to be solved. One of these subspaces is spanned by (high order) element side modes in two dimensions and (high order) element face modes in three dimensions. Solving the subproblems on the element interfaces is a major cost in each step of iteration. To reduce computational cost, various inexact solvers on element interfaces are proposed in this paper, with theoretical analysis and numerical illustrations.

In this paper, we propose a new interative and parallel solver, based on domain decomposition, for the h-p version of the finite element method in two dimensions. It improves our previous work in two aspects: (1) A subdomain may contain several super-elements of the coarse mesh, thus can be of arbitrary shape and size. This makes the solver more efficient and more flexible in computational practice. (2) The p-version components (i.e., the high order side and internal modes) in every element are treated separately, which results in better parallelism.

Two additive Schwarz methods (ASMs) are proposed for the h-p version of the finite element method for two-dimensional elliptic problems in polygonal domains. One is based on generous overlapping of the h-version components (i.e., the linear nodal modes) and nonoverlapping of the p-version components (i.e., the high-order side modes and internal modes). Another is based on nonoverlapping for both the h-version and the p-version components. Their implementations are in parallel on the subdomain level for the h-version components and on the element level for the p-version components. The condition number for the first method is of order O(1 + ln p)2, and for the second one is maxi(1 + ln (Hi pi/hi))2, where Hi is the diameter of the subdomain $\Omega_i$, hi is the characteristic diameter of the elements in $\Omega_i$, pi is the maximum polynomial degree used in $\Omega_i$, and p = maxi pi.