Deformation Of Skeleton Research Articles

Analysis of clinical features and arylsulfatase B gene mutation in thirteen Chinese children with mucopolysaccharidosis type VI

Mucopolysaccharidosis type VI (MPS VI) or Maroteaux-Lamy syndrome is an autosomal recessive lysosomal storage disease caused by a deficiency of arylsulfatase B(ARSB), which is required in the degradation of dermatan sulfate and chondroitin sulfate. The deficiency of ARSB leads to an accumulation of dermatan sulfate and chondroitin sulfate in lysosomes and gross excretion in the urine.Few articles about clinical study and ARSB gene mutation analysis of Chinese MPS VI patients were published. This study aimed to explore the clinical features and characteristics of ARSB gene in Chinese children with MPS VI. Thirteen children were diagnosed as MPS VI by ARSB enzyme activity determination during the period from 2009 to 2013. Their clinical features, radiological findings and urine glycosaminoglycan (GAG) levels were retrospectively reviewed. Direct sequencing was used to identify any mutation in the ARSB gene. Thirteen children were diagnosed at the average age of (3.9 ± 2.2) years with 6 male and 7 female. All of these children presented with severe form and onset at an early age of (1.5 ± 0.8) years.Other clinical features included coarse facies, short stature, skeleton deformity, corneal clouding, hepatosplenomegaly with normal intelligence. The radiological findings in all children were characteristic of dysostosis multiplex, like abnormal development of vertebral bodies of the spine, campylorrhachia and paddle-shaped widened ribs. The MRI in case 2 showed cervical cord compression and multiple cysts degeneration in the corona radiate, cella lateralis and callosum.High urine GAG levels were detected, (307.10 ± 112.14) mg/L (Normally below 70 mg/L) and (722.28 ± 245.68) µg/mg creatinine. The ARSB enzyme activity in leukocytes was low, (13.29 ± 6.22) nmol/(mg×h) [Normal range (47-169) nmol/(mg×h)] by fluorogenic assay and (0.24 ± 0.18) U/g [Normal range (1.01-11.47) U/g] by colorimetric assay. A total of 11 mutations were identified by molecular analysis, including seven previously reported mutations (p.L72R, p.G167R, p.G303E, p.F399L, p. T442M, p.Y255X and p.R327X) and four novel mutations (p.Y175D, p.S403X, p.S464X and large deletion including ex. 2, 3). The c.1197C>G (p.F399L) mutation was the most common mutation in this study (31%). The severe form of MPS VI is characterized by early onset and rapid illness progression. Both the radiological findings and increased urine GAG are important clues to diagnose MPS VI.Large decrease or absence of ARSB activity is diagnostic for MPS VI.Four novel mutations of ARSB gene were identified. The reported mutation c.1197C>G (p.F399L) was the hot-spot mutation in this study.

Formulation of thermo-hydro-mechanical coupling behavior of unsaturated soils based on hybrid mixture theory

Thermo-Hydro-Mechanical (THM) coupling processes in unsaturated soils are very important in both theoretical researches and engineering applications. A coupled formulation based on hybrid mixture theory is derived to model the THM coupling behavior of unsaturated soils. The free-energy and dissipative functions for different phases are derived from Taylor’s series expansions. Constitutive relations for THM coupled behaviors of unsaturated soils, which include deformation, entropy change, fluid flow, heat conduction, and dynamic compatibility conditions on the interfaces, are then established. The number of field equations is shown to be equal to the number of unknown variables; thus, a closure of this coupling problem is established. In addition to modifications of the physical conservation equations with coupling effect terms, the constitutive equations, which consider the coupling between elastoplastic deformation of the soil skeleton, fluid flow, and heat transfer, are also derived.

Hematopoietic Stem Cell Transplantation for Thalassemia

Thalassemia is an autosomal recessive disorder associated with defective synthesis of the α- or β-chain of hemoglobin. For β-thalassemia major patients, therapeutic options are either monthly red cell transfusions and chelation therapy or allogeneic stem cell transplant. Stem cell transplant is the only curative approach and success is inversely correlated with the degree of iron overload and hepatic damage. Without transfusions, thalassemic patients have tremendous skeleton deformities, as well as hepatomegaly and splenomegaly due to expansion of the hematopoietic system with extramedullary hematopoiesis. Allogeneic hematopoietic stem cell (HSC) transplantation (HSCT) in thalassemia has been a cornerstone in the development of HSCT. The rational basis of HSCT in thalassemia consists of substituting the thalassemic HSC bearing ineffective erythropoiesis with an allogeneic one capable of effective erythropoiesis. This cellular replacement therapy is not limited to the diseased erythropoietic component, but leads to the replacement of the entire hematopoietic system. Nevertheless, it is an efficient way to obtain a long-lasting, probably permanent, clinically effective correction of hemolytic anemia, thus avoiding transfusion requirements and associated complications . The transplantation approach for a nonmalignant disease is much different from transplantation in malignancies. In the former setting, the detrimental immunologic proprieties [GVHD] of the engrafted HSC are not balanced by an antimalignancy effect. This characteristic must be always considered in determining the risk/benefit ratio and therapeutic decision such as the kind and intensity of the conditioning regimen, GVHD prophylaxis, source of HSC, and adoptive posttransplant therapies. The Pesaro group developed a prognostic scheme to predict transplant outcome in patients younger than age 17. This prognostic scheme included three variables all related to iron burden: quality of chelation received for the entire life before transplantation; hepatomegaly; and the presence of liver fibrosis at pretransplant hepatic biopsy examination. These variables stratified patients into three groups based on them having none, or one/two, or all three of the risk factors. Overall survival and thalassemia-free survival were significantly different in the three groups: 94% and 87% in the low-risk group, 84% and 81% in the intermediate-risk group, and 70% and 58% in the high-risk group, respectively. The rate of rejection/thalassemia recurrence was much higher in thalassemic patients than in patients transplanted because of malignancies. Several factors have been invoked to explain this difference: massive pretransplant exposure to blood products, not having received any chemotherapy before transplant, expanded erythropoietic marrow, and possibly splenomegaly. Key Words: Hematopoietic, Stem cell, Thalassemi.

Modeling of coupled THMC processes in porous media

For landfill monitoring and aftercare, long-term prognoses of emission and deformation behaviour are required. Landfills may be considered as heterogeneous porous soil-like structures, in which flow and transport processes of gases and liquids interact with local material degradation and mechanical deformation of the solid skeleton. Therefore, in the framework of continuous porous media mechanics a model is developed that permits the investigation of coupled mechanical, hydraulical and biochemical processes in municipal solid waste landfills.

Simulation of Deformation and Fracture of Fluid-saturated Porous Media with Hybrid Cellular Automaton Method

In the paper we propose the method of numerical simulation of fluid-saturated porous media, that represents the combination of particle method and finite-difference method, namely hybrid cellular automaton method. It allows explicit taking into the account inelastic deformation, dilation and fracture of solid skeleton as well as the influence of pore pressure on the stress state of the skeleton and the redistribution of a fluid in filtration volume of porous medium. We applied the method to study the influence of viscous compressible liquid in pores of material to its strength and fracture. It has been shown that the influence of the liquid in pores significantly depends on elastic-plastic properties of material of solid skeleton.

An alternative Biot's formulation for dissipative porous media with skeleton deformation

This paper presents an alternative formulation of Biot's theory to account for the elastic frame effects in a porous medium in which the acoustical properties of the fluid phase are predicted with an equivalent fluid model. This approach was originally developed for a double porosity medium. In this paper, the alternative formulation is applied to predict the transmission loss and absorption coefficient in the case of a single layer fibrous material, a multi-layer system, vibrating perforated plates, and porous composite materials. In the proposed formulation the coupling coefficients in Biot's poroelasticity equations are expressed in terms of the dynamic volumic mass and dynamic bulk modulus. By doing so, the elastic properties of the material frame are considered independently from the properties of the fluid. This formulation is implemented in the form of a transfer matrix algorithm which is validated against experimental data on sound absorption and sound transmission which are obtained for a range of various sound excitations and material arrangements. It is shown that this approach is able to predict accurately the acoustical properties of vibrating perforated plates and porous composites. The proposed approach is sufficiently general to be implemented in a finite element method.

Degradation behaviour analysis of SMA aggregate and skeleton

Based on laboratory tests and field materials evaluation, the inner frictional resistance of SMA skeleton was investigated and then the degradation behaviour of SMA skeleton was characterized for recycling purpose. Inner frictional resistance test was designed to investigate the skeleton characteristics of SMA aggregate mixture. The experimental results indicate that SMA skeleton has much stronger inner frictional resistance than AC skeleton, and coarse aggregates provide main contributions to the inner frictional resistance of SMA skeleton. Crushing test and superpave gyratory compactor (SGC) test were designed to reveal the degradation behaviour of SMA skeleton. To verify the laboratory characterization, field materials were also evaluated. The results indicate that the degradation of SMA skeleton is not random but has fixed internal trend, especially the 4.75mm aggregate plays a key role in the graded aggregates. Based on the testing results, it can be concluded that long-term repeated loading can cause degradation of SMA skeleton. However, the gradation does not keep deteriorating under repeated loading. When the inner frictional resistance is small enough, outside pressure will cause flow deformation of skeleton instead of degradation. Thus, well-designed SMA aggregate mixture is valuable for recycling after long-term in service. And it is important to restore the skeleton, especially the coarse aggregate part.

Structural integrity assessment and stress measurement of CHASNUPP-1 fuel assembly skeleton

A fuel assembly (FA) structure without fuel rods is called FA skeleton which is a long and flexible structure. This study has been made in an attempt to find the structural integrity of the Chashma Nuclear Power Plant-1 (CHASNUPP-1) FA Skeleton at room temperature in air. Non-linear buckling analysis has been performed using ANSYS 13.0, in-order to determine the buckling behavior of the FA skeleton as well as the location/values of the maximum stress intensity and stresses developed in axial direction under applied compression load of 4900N. The finite element (FE) model of spacer grids, guide thimbles with dash-pots & flow holes, in addition to spot welds between spacer grids and guide thimbles, has been developed using Shell 181 element. The FA skeleton is a non-straight structure. Its actual behavior of the geometry is non-linear. The value of the perturbation force is related to the geometry of the model and/or the tolerance defined for the geometry. Therefore, a sensitivity study has been made to determine the appropriate value of an arbitrary perturbation load.It has been observed that FA skeleton deformation values obtained through FE Analysis & Experiment (Technical Report, 1994a,b) under applied compression load are comparable and show linear behaviors. Therefore, it is confirmed that buckling of FA skeleton will not occur at the specified load. Moreover, the values of stresses obtained at different locations of the guide thimbles are also comparable with the stress values of the experiment determined at the same locations through strain gauges.Since the results of both studies (analytical & experimental) are comparable, therefore, validation of the FE methodology is confirmed. The SINT and stresses are less than the design stress limit of the materials used for the grid (ASTM, 2013) and the guide thimble (ASTM, 2012). Therefore, the structural integrity criterion of CHASNUPP-1 FA Skeleton is fulfilled safely.

Full 3D investigation and characterisation of capillary collapse of a loose unsaturated sand using X-ray CT

The aim of this paper is to characterise in 3D the capillary collapse phenomenon using X-ray Computed Tomography (X-ray CT) during water infiltration into a partially saturated soil. To understand the mechanisms leading to capillary collapse, we progressivelly saturated a specimen of sand by controlling the water pressure using the negative water column technique. During this imbibition process, we followed the granular structure using X-ray CT. The microstructure was analysed to assess the volume of water filling the pores and deformation of the granular skeleton using Volumetric Digital Image Correlation tools. Matheron’s granulometry was used in parallel to characterize the initial microstructure and its evolution during the imbibition. We show that the collapse phenomenon can occur in a clean sand and can be controlled continuously with the negative water column technique. The volume change of the specimen at local scale started at a particular water content which coincided with the coalescence of capillary bridges between grain clusters. Gravity effects leading to a non-negligible gradient of the hydrostatic pressure along the specimen’s height were observed and induced a vertical gradient of strain. Localisation of the vertical strain on conical surfaces and of the volumetric strain and water content at the bottom corner of the specimen appeared during the imbibition process. These localisations are thought to be due to an inhomogeneity of the initial density or/and an effect of cell walls facilitating the sliding of grains and the provision of water along preferential paths. However, in spite of those localisations, macroscopic measurements at the scale of the sample were representative of the local behaviour of the unsaturated sand.

Consolidation of a Poroelastic Half-Space

A porous medium is an elastic solid permeated by an interconnected network of pores filled with a fluid. Both solid and pore network are assumed to be continuous so as to form two interpenetrating continua. The theory of poroelasticity investigates the time-dependent coupling between the deformation of the elastic solid skeleton and fluid flow within the skeleton. The solid-to-fluid and fluid-to-solid couplings are assumed to occur instantaneously in the quasi-static approximation in which elastic wave propagation is ignored. Consolidation of a poroelastic body takes place when it is acted upon by surface loads. The study of consolidation of a poroelastic half-space or stratum has received much attention due to its geophysical and engineering applications. The aim of the present paper is to review recent work on the subject, indicating the assumptions made, methods used and conclusions drawn.

Modelling water retention and volume change behaviours of unsaturated soils in non-isothermal conditions

This study presents a simple approach to modelling the effect of temperature on the soil–water retention curves (SWRCs) of deformable soils and takes into consideration the following two aspects: (1) the effect of temperature on the liquid–gas interfacial tension and (2) temperature-induced deformation of the soil skeleton. The first aspect, the temperature effect, can be modelled using an equation proposed by Grant and Salehzadeh [18], but the second aspect is generally neglected in the literature. To quantify the thermo-hydro-mechanical (THM) deformation of unsaturated soils (i.e., the second aspect mentioned above), a simple volume change equation, referred to as the non-isothermal SFG volumetric equation, is proposed on the basis of the original SFG framework [37]. A three-dimensional THM yield surface in the space of net mean stress, suction and temperature is presented here. The proposed volume change equation is integrated into the non-isothermal SWRC by means of a simple hydro-mechanical coupling law [38]. The performance of the non-isothermal SFG volumetric equation and the non-isothermal SWRC equation is investigated through several numerical examples. A number of experimental results reported in the literature are employed to confirm the validity of the proposed non-isothermal SFG volume change equation and the non-isothermal SWRC equation.

Coupled analysis of bifurcation and shear band in saturated soils

The focus of this study is the analysis of the onset of a shear band in saturated soils under biaxial stress conditions taking into account bifurcation in both pore pressure and soil skeleton. By considering the saturated soil as a two-phase medium, the inhomogeneous displacement and pore pressure fields are assumed to be nonlinear and satisfy the continuity conditions of displacements, displacement gradients and excess pore pressure on the boundaries of the band. It is shown that bifurcation may take place in loose, contractive soils in the form of two-phase diffuse mode or localized mode of soil skeleton deformation. For low permeability saturated soils, the onset of a shear band occurs at peak friction, with the shear band parallel to Coulomb's failure plane. Numerical examples using a simple stress–strain model are given to demonstrate the occurrence of the onset of a shear band and its inclination, as a function of the void ratio and the initial consolidation pressure.

An extended finite element method for hydraulic fracture propagation in deformable porous media with the cohesive crack model

In this paper, a fully coupled numerical model is developed for the modeling of the hydraulic fracture propagation in porous media using the extended finite element method in conjunction with the cohesive crack model. The governing equations, which account for the coupling between various physical phenomena, are derived within the framework of the generalized Biot theory. The fluid flow within the fracture is modeled using the Darcy law, in which the fracture permeability is assumed according to the well-known cubic law. By taking the advantage of the cohesive crack model, the nonlinear fracture processes developing along the fracture process zone are simulated. The spatial discretization using the extended finite element method and the time domain discretization applying the generalized Newmark scheme yield the final system of fully coupled nonlinear equations, which involves the hydro-mechanical coupling between the fracture and the porous medium surrounding the fracture. The fluid leak-off and the length of fracture extension are obtained through the solution of the resulting system of equations, not only leading to the correct estimation of the fracture tip velocity as well as the fluid velocity within the fracture, but also allowing for the eventual formation of the fluid lag. It is illustrated that incorporating the coupled physical processes, i.e. the solid skeleton deformation, the fluid flow in the fracture and in the pore spaces of the surrounding porous medium and the hydraulic fracture propagation, is crucial to provide a correct solution for the problem of the fluid-driven fracture in porous media, where the poroelastic effects are significant.

Textural versus electrostatic exclusion‐enrichment effects in the effective chemical transport within the cortical bone: A numerical investigation

Interstitial fluid within bone tissue is known to govern the remodelling signals' expression. Bone fluid flow is generated by skeleton deformation during the daily activities. Due to the presence of charged surfaces in the bone porous matrix, the electrochemical phenomena occurring in the vicinity of mechanosensitive bone cells, the osteocytes, are key elements in the cellular communication. In this study, a multiscale model of interstitial fluid transport within bone tissues is proposed. Based on an asymptotic homogenization method, our modelling takes into account the physicochemical properties of bone tissue. Thanks to this multiphysical approach, the transport of nutrients and waste between the blood vessels and the bone cells can be quantified to better understand the mechanotransduction of bone remodelling. In particular, it is shown that the electrochemical tortuosity may have stronger implications in the mass transport within the bone than the purely morphological one.

Geometrical Remote Steric Effects in 4,5-Disubstituted-9,10-dihydrophenanthrenes: Expansion of Prestrained C9–C10 Bond in Di(spiroacridan) Derivatives

Abstract By attaching bulky substituents at the bay region of di(spiroacridan)-substituted dihydrophenanthrene 1a, the prestrained C9–C10 bond in the dihydrophenanthrene (DHP) skeleton of 1c–1e is expanded from 1.634(2) to 1.649(3)–1.652(6) Å, which demonstrates the bond expansion through remote steric effects. Twisting deformation of the DHP skeleton is the key to transfer the steric bulkiness from the C4/C5 positions to cause the additional strain in the C9–C10 bond.

Dynamics simulation of the interaction between serine and water

Using the first principles density functional theory (DFT), we simulated the neutron scattering spectra of the hydration dynamics of serine. Experimental data analyses have shown that dissociative H2O molecules were more likely to form hydrogen bonds (H-bonds) with an -OH group in monohydrated serine and easily shift to a -NH3 (+) group at a higher hydration level [P. Zhang, Y. Zhang, S. H. Han, Q. W. Yan, R. C. Ford, and J. C. Li, J. Phys. Chem. A 110, 5000 (2006)]. We set the 1:1 ratio hydrated compounds at the two positions and found that the H2O could be optimized to form H-bonds with -OH and -NH3 (+) separately. When the simulated phonon signals of the -OH···H2O and -NH3(+)···H2O combinations were summed on a 3:1 scale, the calculating spectra were in good agreement with the experimental results, especially for the peak at 423 cm(-1) of the -OH···H2O combination and the peak at 367 cm(-1) of the -NH3(+)···H2O combination, which mutually complemented the real spectrum. We confirm that H2O may break the intermolecular H-bonds of the interlaced binding -OH to form a new structure, and that with the skeleton deformation of serine, H2O forms stronger H-bonds more often with the -NH3 (+) side indicating the flexible dynamic mechanism of the serine hydration process.

Topology optimization of fluid–structure-interaction problems in poroelasticity

This paper presents a method for applying topology optimization to fluid–structure interaction problems in saturated poroelastic media. The method relies on a multiple-scale method applied to periodic media. The resulting model couples the Stokes flow in the pores of the structure with the deformation of the elastic skeleton through a macroscopic Darcy-type flow law. The method allows to impose pressure loads for static problems through a one way coupling, while transient problems are fully coupled modeling the interaction between fluid and solid. The material distribution is determined by topology optimization in order to optimize the performance of a shock absorber and test the pressure loading capabilities and optimization of an internally pressurized lid.

Deformation of the erythrocyte cytoskeleton in tank treading motions

By coupling a fluid–structure interaction algorithm with a three-level multiscale structural model, we simulate the tank treading responses of erythrocytes (red blood cells, or RBCs) in shear flows. The focus of this study is on the transient process involving the development of the local area deformation of the protein skeleton due to the slip between the lipid bilayer and the protein skeleton. The fluid motion is depicted within the Stokes-flow framework, and is mathematically formulated with the boundary integral equations. The structural model takes into account the flexible connectivity between the lipid bilayer and the protein skeleton as well as viscoelastic responses. Under the assumption that the natural biconcave configuration of the protein skeleton is its reference state (i.e. the state in which the skeleton has uniform pressure and zero shear stress), we reach the following conclusions: (1) during tank treading motions it takes long relaxation time for significant skeleton area deformations to establish; (2) depending on the initial orientation of the cell with respect to the incoming flow, two responding modes have been identified. One of them is characterized by oscillations in cell geometry (breathing) and orientation (swinging). The other is a steady membrane-circulating motion; (3) the oscillatory motions (breathing and swinging) are closely related to the inequality of the dimples and the rim associated with the shape memory effect. In the first response mode the regions corresponding to the dimples in the original state circulate around the cell, creating unsteadiness in the fluid–structure interaction problem and leading to oscillatory behaviors such as breathing and swinging motions.

Model and Finite Element Analysis of a Bus Body

ANSYS is used as the finite element computing platform to analysis a certain type of bus body frame under four load conditions of bending conditions, reversing conditions, the bending and torsion conditions and the emergency braking conditions. The constraints and load approach in the four conditions are given in this paper. A certain type of bus body skeleton program and the finite element analysis are conduct. The result shows that: (1) Bus body frame changing brings the re-distribution of the stress, making the overall stress and deformation of the body skeleton relatively uniform. (2) The improved program makes more than 250KG weight losing of the body frame and the changing location of the maximum deformation under the bending conditions. The maximum bending deform increased is only 8.92%.

Finite element simulation for fluid–solid coupling effect on depressurization-induced gas production from gas hydrate reservoirs

Natural gas production from hydrate reservoirs is a physical and chemical seepage process of multiphase and multicomponent in nonisothermal condition. A gas–water two-phase hydro-mechanically coupled model is established to simulate the complex performance of depressurization-induced gas production from hydrate reservoirs. The model considers the heat conduction and convection, the variation of physical and mechanical properties as a result of hydrate dissociation, and the interaction between fluid seepage in porous and rock skeleton deformation. With the finite element approximation technique, a coupled simulator is developed. Case studies of gas production from hydrate reservoirs by depressurization are presented, and the fluid–solid coupling effect is mainly discussed.The results show that the overall fluid–solid coupling effect reduces the depressurization-induced gas production from hydrate reservoirs. The rock skeleton deformation can shrink reservoir porosity and increase the elastic drive energy, which favors to enhance gas production to some extent. In contrast, the permeability and porosity reduction due to sandstone deformation can lead to the decrease of gas production significantly. The physical properties variation in the fluid–solid coupling effect has a major impact on gas production of hydrate reservoirs. The fluid–solid coupling effect is a key factor worthy of close attention in the exploitation of hydrate reservoirs.