Thiol-Functionalized Mesoporous Silica for Effective Trap of Mercury in Rats

The chance of exposure to heavy metal for human being rises severely today due to the increasing water contamination and air pollution. Here, we prepared a series of thiol-functionalized mesoporous silica as oral formulation for the prevention and treatment of heavy metal poisoning. The successful incorporation of thiol was verified by the FTIR spectra. SBA15-SH-10 was used for the study as it is of uniform mesopores and fine water dispersibility. In simulated gastrointestinal fluid, the thiol-functionalized mesoporous silica can selectively capture heavy metal, showing a very high affinity for inorganic mercury (II). The blood and urine mercury levels of rats fed with a diet containing Hg (II) and material were significantly lower than those of rats fed with the metal-rich diet only. On the contrary, the mercury content in fecal excretion of the treatment group increased more than twice as much as that of the control group. This result indicated that SBA15-SH-10 could effectively remove mercury (II) in vivo and the mercury loaded on SBA15-SH-10 would be excreted out. Hence, SBA15-SH-10 has potential application in preventing and treating heavy metal poisoning via digestive system

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe

Fast solvers for concentrated elastic contact problems

Rail transportation plays an important role in our everyday life, and there is fast development and modernization in the railway industry to meet the growing demand for swifter, safer and more comfortable trains. At the same time, the security of train operation and the maintenance of rails have to be considered. A lot of research on these issues has been carried out, among which the study of the contact between a train's wheel and the rail is particularly significant. The contact problem considers two elastic bodies. When they are pressed together, a contact area is formed where the two body surfaces coincide with each other. Moreover, an elastic field of stress, strain and displacement arises in each body. These stresses consist of normal stress (pressure) and frictional stress (traction) acting in the tangential direction. When solving the so-called {\it normal contact problem}, we search for the contact area and the pressure on it. The {\it tangential contact problem} is studied when the two bodies are brought into relative motion. If the relative velocity of the two surfaces is small, a creeping motion may be observed which is largely caused by the elastic deformation at the contact region. In those parts of the contact area where the tangential stress is small, the surfaces of the two bodies stick to each other. Otherwise, local relative sliding may occur. The research question is to find the adhesion and slip areas, and the tangential tractions. The solution methods for contact problems have been studied from the late nineteenth century, resulting in a variety of analytic and numerical approaches, w.r.t. their own specific applications. Motivated by the requirement of fast computation for involved applications such as the simulation of railway wheel-rail dynamics, we aim at developing fast numerical solvers for concentrated elastic contact problems in this thesis. Our work focuses on the contact between bodies of linear homogeneous elastic material. Moreover, it is a concentrated contact, i.e. the contact area is small compared to the dimensions of the contacting bodies. The models in use are provided by a variational formulation, which is based on a boundary element method (BEM). It gives rise to a convex optimization problem with linear or nonlinear constraints. The corresponding Karush-Kuhn-Tucker conditions provide the governing equations and contact conditions, that are numerically solved. The most time-consuming part attributes to solving a Fredholm integral of the first kind, resulting from the BEM. The corresponding Green's function expresses the relation between tractions and deformation, using a half-space approach. This integral yields linear systems with coefficient matrices that are dense, symmetric and positive definite. Moreover, they are Toeplitz in two-dimensional (2D) problems and block Toeplitz with Toeplitz blocks in three-dimensional (3D) problems. Fast computing techniques such as the fast Fourier transform (FFT) are explored. We start our work by solving the normal contact problem in Chapter 2. It is modeled by a linear complementarity problem, for which a full multigrid method (FMG) is presented. This method combines a multigrid (MG) method, an active set strategy and a nested iteration technique. It is applied to a Hertzian smooth contact and a rough surface contact. The results show the efficiency and robustness of the FMG method. Tangential contact is considered in Chapter 3 and Chapter 4. A 2D no-slip tangential problem is first studied in Chapter 3, where we mainly solve the surface integral. A fast MG method is proposed with an FFT smoother, where a Toeplitz preconditioner is constructed to approximate the inverse of the coefficient matrix. This smoother reduces many error components but enlarges some smooth error modes. Techniques such as subdomain deflation and row sum modification (RSM) are incorporated. Numerical experiments indicate rapid convergence and mesh-independence of MG with the FFT+RSM smoother. Moreover, FFT+RSM as a stand-alone solver also shows its efficiency. The complexity of these two methods is $\mathcal{O}(n\log (n))$, with $n$ the number of unknowns. We work on the 3D tangential contact in Chapter 4, where a nonlinear constrained optimization problem arises. A fast solver, called TangCG, is proposed. It combines an active set strategy and a nonlinear conjugate gradient method. The most pronounced component of this method is that it employs two types of variables in the adhesion and slip areas. Techniques including the FFT and diagonal preconditioning are also incorporated. The TangCG method is tested for Cattaneo shift problems, with different amounts of slip. It dramatically reduces the computational time, compared to the state-of-art ConvexGS method. The numerical methods presented above are based on the influence coefficients (ICs) that give the relation between tractions and deformation. In Chapter 5, we investigate ICs by computing them numerically. Based on a concentrated contact setting, an elastic model is built for this purpose and a finite element method (FEM) is employed. Suggestions about the FEM meshing and element types are given, considering the accuracy and computational cost. The effects of employing the numerical ICs on contact solutions are examined. The work in this chapter provides a guidance for developing fast solvers for conformal contact problems, which typically are governed by a larger and curved contact region. With the research presented in the present PhD thesis on efficient numerical solution techniques, the numerical solution of full-scale train-rail contact problems may have come one step closer. With the research presented in present PhD thesis, and with the resulting improved numerical solution techniques, it becomes one step closer to incorporate detailed contact models in the numerical simulation of rail vehicle dynamics and in the simulation of rail and wheel wear and track deterioration.Applied mathematicsElectrical Engineering, Mathematics and Computer Scienc

Fire-Induced Spalling Modeling of High-Performance Concrete

Structural EngineeringCivil Engineering and Geoscience

Repair and generalization of hand-made 3D building models

Many 3D GIS applications require 3D building models with different LoD (Level of Detail) that satisfy certain quality criteria. However, because of their complexity, most detailed 3D building models available are still produced manually, which results in inevitable geometric and topological errors. These errors hinder the downstream processing of such models. And existing researches on LoD production either focus on the simplification of smooth polygonal mesh or the generalization of regular prismatic building models. The generalization of detailed 3D building models is still immature. Aiming at producing cleaned models of different LoD for existing hand-made 3D building models, this paper starts by investigating two typical modeling errors of such models, incompleteness and separation. Repair methods with reasonable assumptions of buildings are then proposed for each type of errors. The generalization method based on morphological operations is then employed, coupled with model repair, to generate error-free simplified models.OTB ResearchOTB Research Institute for the Built Environmen

Small concentrations of NaCl help building stable inhibiting layers from 2,5-dimercapto-1,3,4-thiadiazole (DMTD) on AA2024-T3

The interaction of 2,5-dimercapto-1,3,4-thiadiazole (DMTD) with the AA2024-T3 local microstructure (S-phase, secondary phases and matrix) as function of the NaCl concentration is studied. The inhibiting power and the local interaction of DMTD with the metal were studied by in–situ opto-electrochemistry, XPS and Raman spectroscopy. The stability of the inhibiting layers was evaluated by re-exposing the samples to NaCl solutions without inhibitor. The amount of DMTD and its interaction state (chemisorption/physisorption) vary with the local microstructural composition and NaCl concentration. Higher stability of the inhibiting layers is obtained when these are formed in presence of small amounts of NaCl (0.025–0.25 M).Novel Aerospace MaterialsChemE/Product and Process Engineerin

Overview of mechanisms involved during the quenching and partitioning process in steels

The application of the quenching and partitioning (Q&P) process in steels involves a microstructural evolution that is more complex than just the formation of martensite followed by carbon partitioning from martensite to austenite. Examples of this complexity are the formation of epitaxial ferrite during the first quenching step and the formation of bainite, carbides, and carbon gradients as well as migration of martensite/austenite interfaces during the partitioning step. In this work, recent investigations on the mechanisms controlling microstructural changes during the application of the Q&P process are evaluated, leading to phase-formation based concepts for the design of Q&P steels.Materials Science and EngineeringMechanical, Maritime and Materials Engineerin

Two-dimensional vehicular movement modelling at intersections based on optimal control

Modeling traffic flow at intersections is essential for the design, control, and management of intersections. A challenging feature of microscopic modeling vehicular movement at intersections is that drivers can choose among an infinite number of alternative traveling paths and speeds. This makes it fundamentally different from structured straight road sections with lanes. This study proposes a novel method to model the trajectories of vehicles in two-dimensional space and speed. Based on optimal control theory, it assumes drivers schedule their driving behavior, including the steering and acceleration, to minimize the predicted costs. The costs contain the running costs, which consist of the travel time and driving smoothness (longitudinally and laterally), and the terminal cost, which penalizes the deviations from the desired final state. Different than conventional methods, the vehicle motion dynamics are formulated in distance rather than in time. The model is solved by an iterative numerical solution algorithm based on the Minimum Principle of Pontryagin. The descriptive power, plausibility, and accuracy of the proposed model are investigated by comparing the calculated results under several cases, which can be solved from symmetry or analytically. The proposed model is further calibrated and validated using empirical trajectory data, and the quality of the predicted trajectory is confirmed. Qualitatively, the optimal trajectory changes in the range of the shortest path and smoothest path under different weights of the running cost. The proposed model can be used as a starting point and extended with more considerations of intersection operation in the real world for future applications.Transport and PlanningArchitecture and the Built Environmen

Fluvial River Regime in Disturbed River Systems: A Case Study of Evolution of the Middle Yangtze River in Post-TGD (Three Gorges Dam), China

The fluvial river is a kind of open system that can interact with its outside environments and give response to disturbance from outside on the earth. It can adjust itself to the disturbances outside the system and reflects new characteristics in the process of reaching a new equilibrium. The TGD (Three Gorges Dam) constructed at the Yangtze River Upstream was set up to operate in 2003. And it has changed the boundary conditions of the downstream reaches and has broken the long term equilibrium of the Yangtze River system. The reaches alter the river regime to response the disturbance from the TGD. In this paper, the case study Shashi Reach is selected to analyze the variations of the river regime in a river system. The discharge is becoming smoother without large peak or lower discharge for the regulation of the reservoir. The sediment diameter becomes coarser downstream of the TGD and the sediment transport rate decreases as the sediment concentration becomes lower, in spite of the sediment erosion along the reach downstream. The thalweg moves in plane dramatically to adjust itself to reach a new equilibrium. And the topography changes a lot since there are different sediment and flow conditions. The disturbed river system is in the process of reaching a new equilibrium.Rivers, Ports, Waterways and Dredging Engineerin