Three-dimensional recon-struction and analysis of structure characteristics on senile plaques of Alzheimer’s disease

Alzheimer’s disease (AD) is a neurodegenerative dis-order characterized by progressive dementia. The classic neuropathological lesions of Alzheimer’s disease are se-nile plaque (SP) associated with fibrillar and amorphous nonfibrillar amyloid β (Aβ), neurofibrillary tangles (NFTs) and loss of neurons[1,2]. Many studies show that Aβ plays akey role in the pathogenesis of AD, and fibrillar Aβ has relatively high neurotoxic effects[3―5]. Therefore, studying the mechanism of Aβ aggre…     

Effect of Ab_(1-40) on membrane permeability and intracellular free Ca~(2+) of nerve cells

Alzheimers disease (AD) is a kind of progressive neurodegenerative disease, characterized by intracellularfibrillar tangles and extracellular senile plaques, the main component of the plaques are b-amyloid (Ab), composed of 3943 amino acids[1]. Glenner and Wong first isolated Ab peptide and determined the sequence in 1984, after-wards, a series of researches were done on its production, structure determination, aggregation, hydrophobicity, re-ceptor and cell toxicity. Ab is the abnormal fiss…     

Computation of fractal dimension of rock pores based on gray CT images

The characterization of pore structure in rocks is relevant in determining their various mechanical behaviors. Digital image processing methods integrated with fractal theory were applied to analyze images of rock slices obtained from industry CT, elucidating the characteristics of rock pore structure and the relationship between porosity and fractal dimensions. The gray values of pixels in CT images of rocks provide comprehensive results with respect to the attenuation coefficients of various materials in corresponding rock elements, and these values also reflect the effect of rock porosity at various scales. A segmentation threshold can be determined by inverse analysis based on the pore ratios that are measured experimentally, and subsequently binary images of rock pores can be obtained to study their topological structures. The fractal dimension of rock pore structure increases with an increase in rock pore ratio, and fractal dimensions might differ even if pore ratios are the same. The more complex the structure of a rock, the larger the fractal dimension becomes. The experimental studies have validated that fractal dimension calculated directly from gray CT images of rocks can give an effective complementary parameter to use alongside pore ratios and they can suitably represent the fractal characteristics of rock pores.     

Development in the research of molecular mechanism of Alzheimer’s disease

Alzheimer's disease (AD) is a kind of central nervous system disease. The cause of AD is unclear. It is found that the remarkable histopathological characters of AD are senile plaques and neurofibrillary tangles. β-amyloid plays an important role in the formation of senile plaques and the abnormal phosphorylation of Tau protein is the main reason of neurofibrillary tangles. Apolipoprotein E is correlated to AD' s access, and the third pathological character-AMY plaque perhaps represents a new cause of AD. Presenlin and proteinaceous infectious particles are also related with AD. A summary of molecular mechanism for AD and the development of research is presented.     

Numerical Modeling of Dendrite Growth in AI Alloys

Dendritic grains are the most often observed microstructure in metals and alloys. In the past decade, more and more attention has been paid to the modeling and simulation of dendritic microstructures.This paper describes a modified diffusion-limited aggregation model to simulate the complex shape of the dendrite grains during metal solidification. The fractal model was used to simulate equiaxed dendrite growth.The fractal dimensions of simulated AI alloy structures range from 1,63-1.88 which compares well with the experimentally-measured fractal dimension of 1.85; therefore, the model accurately predicts not only the dendritic structure morphology, but also the fractal dimension of the dendrite structure formed during solidification,     

Cholesterol Depletion Reduces the Internalization of β-Amyloid Peptide in SH-SY5Y Cells

Introduction Alzheimer’s disease (AD) is a degenerative disorder othe human brain. A major pathological hallmark of ADis extracellular amyloid plaque deposited in the cerebral parenchyma and vasculature[1]. Currently, muchattention has been focused on th…     

Application of Wavelet Fractal Dimension Estimation Method on Flood Season Staged

Floodwater utilization is an important content in flood management. Controlling the limit water level of reservoir by stage is one of important contents in the management of multi-purpose reservoir＇s floodwater utilization for the sake of more benefits, and reasonable division of stage in flood season is precondition of controlling the limit water level by stage. On the background of Three Gorges Reservoir floodwater utilization management and on the foundation of self-similarity of hydrological series, determining the number of flood season staged in base of conventional statistical method, choosing the Db4 wavelet and Mallat algorithm, the computation mode of wavelet fractal dimension estimation method is proposed and each stage＇s fractal dimension is computed, then the final flood season staged is obtained. The results demonstrate the stages of Three Gorges Reservoir determined by using wavelet fractal dimension method are consistent with that from conventional method, but the fractal dimension results by former method are easier, more stable and objective which ensures the feasibility of the wavelet fractal dimension method applying in flood season staged. The obtained results are the base of deep coping with floodwater utilization management, also are the decision-making gist for the flood forecast, flood control and water allocation reasonably of Three Gorges Reservoir.     

Study of-amyloid adsorption and aggregation on graphite by STM and AFM

Alzheimers disease is the major cause of dementia and the fourth leading cause of death in the developed world after heart disease, cancer and stroke. Pathologi-cally, one of major hallmarks of Alzheimers disease is the formation of insoluble deposits of -amyloid (A) both as diffuse and senile plaques in the brain tissue. The plaques are fibrous masses composed primarily of the 40-42 resi-due A peptides. The two most abundant forms of A are, respectively, the 40 and 42 residue peptide -amylo…     

Dynamics of the generalized 3x + 1 function determined by its fractal images

Two different complex maps were obtained by generalizing 3x ＋ 1 function to the complex plane, and fractal images for these two complex maps were constructed by using escape time, stopping time and total stopping time arithmetic. The dynamics of the generalized 3x＋1 function based on the structural characteristics of the fractal images was studied. We found that：（1） the size and structure of the stable regions, stopping regions, total stopping regions, and divergent regions for the three types of fractal images depend on convergence rate of the map on the x and y axes. （2） The black stable regions constructed, respectively, by escape time and total stopping time are almost overlapped, demonstrating that 3x ＋1 function converged steadily. （3） All of the three fractal images are symmetric to the real axis. The structures on the neighborhood of positive integer number are symmetric to a perpendicular line, which is corresponding to the point or its nearby points on the x axis. And the structures have complicated fractal structure characteristics. These findings indicate that the generalized 3x＋1 function on integer number and its neighborhood contains plentiful information in the complex plane.     

Prediction and calculation for new energy development

Some important questions for new energy development were discussed, such as the prediction and calculation of sea surface temperature, ocean wave, offshore platform price, typhoon track, fire status, vibration due to earthquake, energy price, stock market＇ s trend and so on with the fractal methods （ including the four ones of constant dimension fractal, variable dimension fractal, complex number dimension fractal and fractal series） and the improved rescaled range analysis （R/S analysis）.     

Influence Factors of Fractal Characterization of Reciprocating Sliding Wear Surfaces

The principal purpose of this paper is to investigate influence factors of fractal characterization of reciprocating sliding wear surfaces. The wear testing was completed to simulate the real running condition of the diesel engine 8NVD48A-2U. The test results of wear surface morphology dimension characterization show that wear surface profiles have statistical self-affine fractal characteristics. In general, there are no effects of the profilometer sampling spacing and sampling length and evaluation length on the fractal dimensions of the surfaces. However, if the evaluation length is too short, the structure function logarithm of the surface profile is scattered. The sampling length acting as a filter is an important part of the fractal dimension measurement. If the sampling length is too short, the evaluation of the fractal dimension will have a larger standard deviation. The continuous wavelet transform can be used to improve surface profile dimension characterization.     

Surface plasmon resonance analysis to evaluate the importance of heparin sulfate groups＇ binding with human aFGF and bFGF

Human acidic and basic fibroblast growth factors (aFGF and bFGF) are classic and well characterized members of the heparin-binding growth factor family. Heparin is generally thought to play an extremely important role in regulating aFGF and bFGF bioactivities through its strong binding with them. In order to unravel the mechanism of the interactions between heparin and FGFs, and evaluate the importance of heparin sulfate groups‘ binding with FGFs, surface plasmon resonance analyses were performed using IAsys Cuvettes System. Heparin and its regioselectively desulfated derivatives were immobilized on the cuvettes, aFGF and bFGF solutions with different concentrations were pipetted into the cuvettes and the progress of the interaction was monitored in real-time by Windows-based software, yielding kinetic and equilibrium constants for these interactions. In addition, in order to reduce the delicate difference among the cuvettes, inhibition analyses of mixture of FGFs and immobilized native heparin by modified heparins were also done. The data from these two methods were similar, indicating that all sulfate groups at 2-0, 6-0 and N- in heparin were required for the binding to aFGF; and that their contribution to the binding was in the order 2-O, N- and 6-O-sulfate group.In contrast, definite contribution of the 6-O-sulfate group to the binding with bFGF was most apparent, while the other two sulfate groups appeared to be necessary in the order 2-O and N-sulfate group. These methods established here can be used for analysing the effect of sulfate groups in heparin on the binding with other human FGF members or other heparin-binding proteins.     

An Approach to Extracting Fractal in Remote Sensing Image

In order to apply the spatial structure information to remote sensing interpretation through fractal theory, an algorithm is introduced to compute the single pixd fraetal dimension in remote sensing images. After a computer program was written according to the algorithm, the ETM＋ images were calculated to obtain their fractal data through the program. The algorithm has following characteristics： The obtained fractal values indicate the complexity of image, and have positive correlation with the complexity of images and ground objects. Moreover, the algorithm is simple and reliable, and easy to be implemented.     

Review： Protein folding pathology in domestic animals

Fibrillar proteins form structural elements of cells and the extracellular matrix. Pathological lesions of fibrillar microanatomical structures, or secondary fibrillar changes in globular proteins are well known. A special group concerns histologically amorphous deposits, amyloid. The major characteristics of amyloid are: apple green birefringence after Congo red staining of histological sections, and non-branching 7-10nm thick fibrils on electron microscopy revealing a high content of cross beta pleated sheets. About 25 different types of amyloid have been characterised. In animals, AA-amyloid is the most frequent type. Other types of amyloid in animals represent: AIAPP (in cats), AApoAⅠ, AApoAⅡ, localised AL-amyloid, amyloid in odontogenic or mammary tumors and amyloid in the brain. In old dogs Aβ and in sheep APrP^sc-amyloid can be encountered. AA-amyloidosis is a systemic disorder with a precursor in blood, acute phase serum amyloid A (SAA). In chronic inflammatory processes AA-amyloid can be deposited. A rapid crystallization of SAA to amyloid fibrils on small beta-sheeted fragments, the ‘amyloid enhancing factor‘ (AEF), is known and the AEF has been shown to penetrate the enteric barrier. Amyloid fibrils can aggregate from various precursor proteins in vitro in particular at acidic pH and when proteolytic fragments are formed. Molecular chaperones influence this process. Tissue data point to amyloid fibrillogenesis in lysosomes and near cell surfaces. A comparison can be made of the fibrillogenesis in prion diseases and in enhanced AA-amyloidosis. In the reactive form, acute phase SAA is the supply of the precursor protein, whereas in the prion diseases, cell membrane proteins form a structural source. AI3-amyloid in brain tissue of aged dogs showing signs of dementia forms a canine counterpart of senile dementia of the Alzheimer type (ccSDAT) in man. Misfolded proteins remain potential food hazards. Developments concerning prevention of amyloidogenesis and therapy of amyloid deposits are shortly commented.     

Cr/Mn偏析对高碳轴承钢珠光体–马氏体带状组织的影响分析

The effect of Cr/Mn segregation on the abnormal banded structure of high carbon bearing steel was studied by reheating and hot rolling. With the use of an optical microscope, scanning electron microscope, transmission electron microscope, and electron probe microanalyzer, the segregation characteristics of alloying elements in cast billet and their relationship with hot-rolled plate banded structure were revealed. The formation causes of an abnormal banded structure and the elimination methods were analyzed. Results indicate the serious positive segregation of C, Cr, and Mn alloy elements in the billet. Even distribution of Cr/Mn elements could not be achieved after 10 h of heat preservation at 1200°C, and the spacing of the element aggregation area increased, but the segregation index of alloy elements decreased. Obvious alloying element segregation characteristics are present in the banded structure of the hot-rolled plate. This distinct white band is composed of martensitic phases. The formation of this abnormal pearlite–martensite banded structure is due to the interaction between the undercooled austenite transformation behavior of hot-rolled metal and the segregation of its alloying elements. Under the air cooling after rolling, controlling the segregation index of alloy elements can reduce or eliminate the abnormal banded structure.     

Effect of Fiber Properties on Nonwovens＇ Pore Structures with Fractal Geometry Analysis

Nonwovens＇ pore structures are very important to their mechanical and physical properties. And the pore structures are influenced by the fiber properties and fibers arrangement in web. In this paper, the fractal geometry, in combination with computer image anaysis, is used to express the irregularity of pore size distribution in nonwovens, and the effect of fiber properties on fractal dimension of pore size distribution is discussed by using simulated images which are composed of nonlinear staple fibers. The results show that the fiber properties, such as crimp, diameter, angular distribution, and especially the number of fibers prominently influence the pore structure.     

Comparison of methods for determining orthotropic axes in 3D femur remodeling

The density distribution and internal structure of trabecular bone are modulated by local mechanical environment. In this study, an orthotropic adaptation algorithm was applied to the 3D femur model to simulate the variations of stiffness and orientation of trabecular bone under multi-loading conditions. This algorithm includes the determination of orthotropic axes and the stiffness modification of trabecular bone. Three methods were used to determine the orthotropic axes, i.e. the maximal cycle method, the stress maximum method, and the composite method. We found that the composite method was better than the other two. Firstly, the characteristics of density distribution obtained by using the composite method agreed better with those in real proximal femur. Secondly, the material orientation aligned with the known trabeculaer pattern. Finally, the ratios of the longitudinal modulus to the transverse modulus were also shown to be realistic in three local regions of the proximal femur.     

A novel method to identify the scaling region for chaotic time series correlation dimension calculation

To obtain more accurate correlation dimension estimations for chaotic time series, a novel scaling region identification method is developed. First, points that obviously do not belong to the scaling region associated with the whole double logarithm correlation integral curve are removed using the K-means algorithm. Second, a point-slope-error algorithm is developed to recognize a possible scaling region. Third, the K-means algorithm is used again to further remove a small interval of interfering points in the possible scaling region to obtain a more precise scaling region. The correlation dimension of four typical chaotic attractors and five curves generated by the Weierstrass-Mandelbrot fractal function were calculated using the proposed method. These calculated values were very close to the respective theoretical fractal dimensions. Moreover, the effectiveness of our method in identifying the scaling region was compared with existing methods. Results show that our method can distinguish the scaling region objectively, accurately, automatically and quickly, making estimations of the correlation dimension more precise and affording significant improvements in nonlinear analysis.     

One-Dimensional Fractal Curves and Fractal Dimension Determination

Various methods for evaluating the fractal curves were reviewed and simulated on computer. It is shown box-counting and power spectrum methods generally give poor measuring results, while yard and variation methods could obtain good results. However,owing to multiple influencing factors, further study needs to be done before widespread application of variation method. In order to improve the measuring accuracy of yard method, a new method has been propoed to measure the fractal dimension by changing the instrumental resolutions.