Search

Lymph node metastasis of rabbit VX2 pyriform sinus carcinoma can be enhanced by MR scanning after injecting ultra-small superparamagnetic iron oxide (USPIO) into the submucosa beside the tumor. The metastasis lymph node which fit in with the diagnostic criteria will be placed into the alternating magnetic field after MR scanning. Then, magnetic particles can be heated to the effective therapeutic temperature. And it evaluates the possibility of diagnosis together with therapy in cervical metastasis of pyriform sinus carcinoma. Twenty rabbits bearing VX2 tumor in pyriform sinuses were randomly divided into hyperthermia group and control group after USPIO MR scanning; each group contained 10 rabbits. The hyperthermia for the experimental group was conducted by the alternating magnetic field. After hyperthermia, the detection of apoptosis for the two groups was tested by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL), transmission electron microscopy (TEM), and the expression of Bcl-2 and Bax evaluated by immunohistochemical analysis. The apoptosis rate detected by TUNEL in hyperthermia group was 100 %, while the control group was only 20 % ( p < 0.05). TEM observation showed that cell chromatin condensation and clumping, condensed cytoplasm, endoplasmic reticulum membrane fusion with loose change, and the formation of a bubble could be seen in the hyperthermia group. However, the control group showed a more complete cytoplasm and nucleus. Bcl-2 protein expression in the hyperthermia group was lower than the control group, and Bax protein expression in hyperthermia group was higher ( p < 0.05). USPIO indirect lymphography could localize the metastatic lymph nodes for hyperthermia. And it could make the metastatic cervical lymph nodes apoptosis when placed into the alternating magnetic field. [ABSTRACT FROM AUTHOR]

AZ61 and AM60 magnesium alloys, with higher mechanical strengths than that of the most commonly used AZ31 alloy, were subjected to high-temperature rolling. Although the basal textures of the as-rolled sheets of both alloys were significantly weakened by annealing, the texture weakening was more significant in the latter than in the former. In addition, splitting of the basal pole was not retained after annealing for the AZ61 alloy, but this type of texture was preserved in the case of the AM60 alloy. The formation of statically recrystallized grains with dispersed orientations resulted in the aforementioned change in texture. The difference in the static recrystallization behavior could be attributed to the solute effect of zinc atoms. The annealed AZ61 and AM60 alloy sheets exhibited excellent stretch formability at room temperature, with Erichsen values of 7.8 and 8.5 mm, respectively, comparable to those of aluminum alloys. The higher Erichsen value for the AM60 alloy compared to that of the AZ61 alloy resulted from the more weakened basal texture and the splitting of the basal pole with an inclination angle of ±20° in the rolling direction, which are favorable for basal slip during sheet forming. [ABSTRACT FROM AUTHOR]

The fabrication of magnesium (Mg) alloy sheets with both high mechanical strength and superior cold formability was sought by optimizing the aluminum (Al) content of the alloy sheets. We investigated the influence of varying Al content from 3 wt% to 8 wt% on the texture, mechanical properties, and stretch formability of AM series Mg alloys, processed by high-temperature rolling. The ultimate tensile strength improved steadily from 247 MPa to 303 MPa with an increase in Al, due to solid solution strengthening. The basal texture intensity decreased with increasing Al content, reached a minimum value at 6 wt% Al, and then increased as more Al was added. The weakest basal texture led to the smallest Lankford value and the largest strain hardening exponent in the AM60 (6 wt% Al) alloy. The alloys with lower Al contents of 3–5 wt% exhibited a high fracture elongation of 27%, which continuously decreased to 23% as the Al content increased to 8 wt%. The AM50 alloy exhibited excellent stretch formability with the largest Erichsen value of 9.1, while the AM30 and AM80 alloys showed much smaller Erichsen values of 5.6 and 6.0, respectively. This can be attributed to a good balance among the decreased r -value, increased n -value, and enhanced tensile ductility in the AM50 alloy, despite its basal texture being slightly stronger than that of the AM60 alloy. [ABSTRACT FROM AUTHOR]

Highlights: [•] A moving target detection method based on tracking interest points is proposed. [•] A novel clustering method named as R-means is proposed. [•] These interest points are divided into target points and background points. [Copyright &y& Elsevier]

The microstructural and textural evolution of pure titanium during differential speed rolling (DSR) at 500 °C and subsequent annealing were investigated using electron backscattered diffraction analysis. Twinning only occurs in the initial stage of DSR, and further deformation is dominated by dislocation slip. The as-rolled microstructure is characterized by large deformed grains, which form a major component of the material, and some dynamically recrystallized (DRXed) grains mainly existing in shear band regions. A dramatic change in the rolling texture, from the transverse direction (TD) split texture with basal poles largely tilted at ±40° to the single-peak basal texture, occurs during DSR. This change in texture is accelerated during the late stage of DSR and may be attributed to the gradual lattice rotation of deformed grains caused by enhanced basal slip activity. The basal texture changes back to the TD-split texture with basal poles tilted at ±25° after annealing due to consumption of deformed grains with basal orientations from DRXed grains with the TD-split texture. Subsequent extensive grain growth changes the orientation of the a-axis from parallel to the TD to parallel to the rolling direction, which is the result of the preferential grain growth in that direction. [ABSTRACT FROM AUTHOR]

Abstract: A matrix Kalman filter (MKF) has been implemented for a navigation system using point-based visual and inertial sensors. The observability conditions have been proved by the observability rank criterion based on Lie derivatives. The conditions are: (a) at least one degree of rotational freedom is excited and (b) at least three observed points are not collinear where any two points are linearly independent. Experimental results have demonstrated that the proposed algorithm obtains the same accurate as the line-based algorithm. [Copyright &y& Elsevier]

Highlights: [•] A novel method which is inspired by Human Visual System is proposed in this paper. [•] This method combines three mechanisms of HVS together. [•] DOG filter is used to simulate the contrast mechanism. [•] A Gaussian window is added at a point to simulate the visual attention. [•] The PID algorithm is first introduced to simulate the eye movement of human being. [ABSTRACT FROM AUTHOR]

Microstructural evolution and stretch formability of Mg–3Al–1Zn (AZ31) magnesium alloy sheets warm rolled at 225°C by a single differential speed rolling pass with two different initial microstructures were investigated. A cast ingot and that rolled by one pass at a high temperature of 550°C with average grain sizes of ~470μm and ~19μm, respectively, were used as starting materials. Both warm rolled sheets exhibit deformation microstructure in as-rolled condition and the occurrence of texture randomization during subsequent annealing as a result of static recrystallization. New recrystallized grains with a large orientation spread tend to persist in the original orientations of parent deformed grains and twin hosts. Regarding the nucleation sites at pre-existing grain boundaries and double twins, static recrystallization preferentially occurs at the sides of deformed grains and within double twins with their c-axes inclining toward the rolling direction (RD), resulting in a stable end annealing texture with a basal pole tilting toward the RD. For the sheet warm rolled from a cast ingot, incomplete recrystallization originating from less stored energy in the interiors of large deformed grains results in an insufficient texture weakening and an inhomogenous microstructure. Both sheets possess an improved stretch formability compared with conventional AZ31 alloy sheets due to the weakened textures. Benefiting from a weaker basal texture and a more homogenous microstructure, the sheet rolled at 550°C followed by warm rolling at 225°C exhibits a higher Erichsen value of 8.2 compared with that (6.1) of the sheet warm rolled directly from a cast ingot. [ABSTRACT FROM AUTHOR]

As-explosive welded clad plates usually show poor ductility due to heavily deformed microstructures developed after explosive welding (EXW). In this study, the feasibility of improving mechanical properties of an EXWed Mg–6Al–1Zn–1Ca (AZX611)/Al–0.6Mg–0.6Si–0.1Fe (A6005C) (all in wt%) clad plate has been explored by subsequent hot-rolling. Increasing the thickness reduction per pass from 10% to 28% or decreasing the rolling temperature from 430 °C to 250 °C is shown to enhance tensile properties. The joint sheet rolled at 250 °C with a thickness reduction per pass of 28% shows a large fracture elongation of 15%, which is significantly higher than that of the as-EXWed clad plate, 1.2%. Microstructure characterization by means of scanning electron microscope, electron backscatter diffraction and transmission electron microscope reveals that the substantial improvement in ductility is intimately related to a significant reduction of the accumulated strain in AZX611 and A6005C alloy sheets and an elimination of the interface delamination formed during EXW. A certain degree of anisotropic mechanical properties is observed in all sheets regardless of rolling conditions, which can be ascribed to the mechanical anisotropy originated from the AZX611 and A6005C alloy sheets. • Producing high performance lightweight Mg/Al joint sheets by explosive welding followed by conventional hot rolling. • Characterizing microstructure and evaluating mechanical properties of EXWed Mg/Al joint sheets rolled in different conditions. • Providing an in-depth understanding of the relationship between rolling condition, microstructure and mechanical properties. [ABSTRACT FROM AUTHOR]

Abstract: Mg–3Al–1Zn magnesium alloy sheets rolled at 350°C, 450°C and 525°C, which exhibit approximately the same grain size but a significant decrease in basal texture intensity with increasing rolling temperature, were used for investigating the influence of initial texture on deep drawing behaviour at room temperature. The sheets rolled at 350°C and 450°C fracture at drawing ratios of 1.5 and 1.7, respectively, while the sheet rolled at 525°C can be successfully drawn at a large drawing ratio of 1.8. The fracture site changes from the shoulder of drawn cup to the edge of the flange with the weakening of initial basal texture. At the flange, the basal texture dramatically changes to the TD-texture with basal planes perpendicular to the sheet plane accompanied with sheet thickening. Both tensile twinning and basal slip contribute to this texture change due to compressive stress along the circumferential direction. In the case of weak initial texture, relatively restricted tensile twinning and more activated basal slip delay the development of the TD-texture, which is favoured for maintaining deformation capability at the flange and in turn enhances deep drawability. The deformation behaviour is discussed in terms of the change in Schmid factor for basal slip during deep drawing. [Copyright &y& Elsevier]

Abstract: The annealing behaviours of Mg–3Al–1Zn magnesium alloy sheets warm rolled at 225°C and 150°C using differential speed rolling, which are mainly characterized by dynamic recrystallized microstructure and deformation microstructure, respectively, were investigated at different annealing stages. Static recrystallization occurs for the sheet rolled at 150°C while only grain growth proceeds for the sheet rolled at 225°C. For the sheet rolled at 225°C, the grain growth of dynamic recrystallized grains eliminates the basal pole inclination in the rolling direction. In contrast, for the sheet rolled at 150°C, the grain growth after static recrystallization retains the basal pole inclination, which is favoured for sheet forming. This difference in texture evolution may be attributed to the dynamic or static recrystallization prior to grain growth, which results in residual dislocation densities for the former and thus leads to the preferential growth of harder oriented basal grains at the centre of (0001) pole figure with lower dislocation densities during annealing. [Copyright &y& Elsevier]

Abstract: The Mg–3Al–1Zn magnesium alloy sheets rolled at 573 and 798K characterized by strong and weak basal textures, respectively, were further subjected by a single high temperature rolling pass at 798K. The sheet rolled only at 798K throughout rolling exhibits a double peak texture in both of as-rolled and annealed conditions. By contrast, for the sheet rolled at 573 and 798K, the reduction rate of basal texture intensity is larger and the single peak of the rolling texture changes to the double peak with basal poles largely tilting in the RD at ∼20° after annealing, which is rarely observed in wrought magnesium alloys. This phenomenon is resulted from static recrystallization and may be related to enhanced pyramidal 〈c+a〉 slip during high temperature rolling due to the initial strong basal texture. [Copyright &y& Elsevier]

Poor formability of rolled magnesium (Mg) alloys extremely restricts applications in form of sheets originating from formation of strong basal texture. Recently, we found that increasing rolling temperature from 723 to 798 K for a AZ31 Mg alloy can significantly improve stretch formability due to remarkable texture weakening after annealing. In this study, static recrystallization behaviors of AZ31 alloy sheets rolled at 723 and 798 K were investigated by electron backscattered diffraction analyses at different annealing stages in order to understand the origin of high temperature rolling on texture weakening. For both sheets, similar deformation microstructures with approximately the same types and fractions of twins exist in the as-rolled condition and recrystallized grains are mainly formed at pre-existing grain boundaries due to discontinuous recrystallization during subsequent annealing. However, only the basal texture of the latter remarkably weakens due to the formation of new recrystallized grains with well-dispersed orientations. Non-basal slips enhanced during high temperature rolling at 798 K are most likely responsible for the texture randomization as a result of rotations of recrystallization nuclei. [ABSTRACT FROM AUTHOR]

Conclusions: During total ossicular replacement surgery, a better auditory functional recovery is obtained when the stapes footplate is retained. Also, the best hearing restoration is obtained when the total ossicular replacement prosthesis (TORP) is placed onto the center of the stapes footplate during operation. Objectives: The effects of TORPs connecting to different positions of the stapes footplate or oval window membrane on hearing restoration were investigated. Methods: A healthy volunteer's right ear was scanned to obtain the CT data, which were digitalized using a self-compiling program and imported into PATRAN software to establish a 3D finite element model, and a harmonic response analysis was carried out using NASTRAN software. Then the effect of TORPs connecting to different positions on the stapes footplate or oval window membrane was studied. Results: The displacement curve of the stapes footplate was in good agreement with that of the normal ear when the TORP was connected onto the center of the stapes footplate. The best hearing restoration was obtained when the TORP was placed onto the center of the stapes footplate. The displacement curve of the stapes footplate was basically equivalent to that of the normal ear when the TORP was connected onto the anterior site, while the displacement curve of the stapes footplate differed from that of the normal ear when the TORP was connected onto the posterior site. In addition, when the TORP was connected onto the oval window membrane, the displacement curve of the stapes footplate was different from that of the normal ear [ABSTRACT FROM AUTHOR]

Objectives: We sought to identify the prevalence of otitis media with effusion (OME) in urban Chinese children in Xi'an, China. Methods: Five kindergartens and 3 primary schools were randomly selected in the urban area of Xi'an. Screening otoscopic and tympanometric examinations were performed on 2,902 children (1,491 boys and 1,411 girls) 2 to 8 years of age. Children with an abnormal tympanogram and simultaneous otomicroscopic signs of effusion were given a diagnosis of OME. Results: The overall prevalence of OME was 4.3%. By age group, the prevalence was 14.0% in 2-year-olds, 8.3% in 3-year-olds, 5.0% in 4-year-olds, 4.9% in 5-year-olds, 2.8% in 6-year-olds, 1.7% in 7-year-olds, and 3.2% in 8-year-olds. The prevalence rate for OME was 4.7% for boys versus 3.9% for girls, and 3.0% in the right ear versus 2.7% in the left, showing no statistically significant difference between genders or between ear sides (p > 0.05). Conclusions: The prevalence of OME in urban areas of Xi'an is not high in comparison with that of the same age group in surrounding areas. [ABSTRACT FROM AUTHOR]

Abstract: The effects of increasing rolling temperature from 723K to 828K at the last rolling pass on microstructure, texture, mechanical properties and stretch formability of a Mg–3Al–1Zn magnesium alloy previously rolled at 723K were investigated. In the as-rolled condition, the basal texture strengthens slightly with increasing the rolling temperature whereas it weakens more remarkably after static recrystallization during annealing for the sheets rolled at higher temperatures. Only by increasing the rolling temperature from 723K to 798K, the Erichsen value is significantly increased from 4.5 to 8.6 due to the weakened texture for the annealed sheets. Further increasing the last rolling temperature does not appear to further improve the stretch formability. [Copyright &y& Elsevier]

This paper studies the design of variable structure systems with saturation inputs. Sliding mode domain, reaching domain, and unescapable reaching domain of linear systems with variable structure are defined and investigated. When the state matrix of the linear system is Hurwitz, the stability of the variable structure systems is proven by using passivity theory. Moreover, variable structure systems with novel nonlinear switching surfaces are proposed for second order systems. Two strategies for designing variable structure control for high order linear systems are also proposed, such as stepby-step variable structure control and moving-surface variable structure control, which were found to guarantee that the reaching condition of the variable structure control is always satisfied. Finally, an illustrative example pertaining to the attitude control of a flexible spacecraft demonstrates the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]

Abstract: The relationship between the Zn concentration and stretch formability of the rolled Mg–x wt.%Zn–0.2wt.%Ce (Mg–xZn–0.2Ce here after) alloys was investigated. Zn addition of a dilute concentration of more than 0.5wt.% effectively modified the basal plane texture, which was characterized by the splitting basal pole toward the TD. However, further Zn addition showed no strong effect on the distribution and intensity of the basal plane texture. The Mg–1.5Zn–0.2Ce alloy showed significant stretch formability. On the other hand, further Zn addition deteriorated the stretch formability of the Mg–xZn–0.2Ce alloys, although it showed no effect on the distribution and intensity of the basal plane texture. The deterioration of the stretch formability of the Mg–xZn–0.2Ce alloys with high Zn concentrations was suggested to be ascribed to solid solution hardening. Moreover, it was suggested that not only the texture but also solid solution softening plays an important role in the enhanced stretch formability of the Mg–xZn–0.2Ce alloys. [Copyright &y& Elsevier]

Differential speed rolling (DSR) was carried out on commercial pure titanium at rolling temperatures from room temperature to 773K. The basal texture appears when the rolling temperature is higher than 573K and it lacks stability during annealing. Originating from texture effects, the DSRed sheet exhibits a larger Lankford value and a smaller planar anisotropy, which lead to a remarkable improvement in stretch formability regardless of a decrease in tensile elongation compared with symmetrically rolled sheet. [Copyright &y& Elsevier]

The Mg–3Al–1Zn magnesium alloy sheets with initial extrusion and casting microstructures were symmetrically rolled at a high temperature of 823K, followed by a warm rolling at 498K. The initial texture plays a vital role in texture development and results in inclination angle of split basal pole varying from ±15° to ±40°. The sheet rolled perpendicular to extrusion direction exhibits a homogeneous microstructure with an inclination angle of ±25° and the highest Erichsen value of 9.7. [Copyright &y& Elsevier]

Abstract: The microstructural and textural evolution of the hot-extruded AZ31 alloy plate during differential speed rolling (DSR) has been investigated. For the hot-extruded plate, a large texture gradient exists in the thickness direction while the grain size distribution is nearly homogenous. The textural evolutions at near-surface and mid-layer regions are different between the DSR processed and the normal symmetric rolled sheets. The inclination of basal pole at the mid-layer increases at an accelerating rate with progress of the DSR processing due to the enhancement of the unidirectional shear bands. The deformation tends to concentrate on the previously formed shear bands, which exhibit a favored crystalline orientation for further shear localization. [Copyright &y& Elsevier]