bluuebunny/crossref_metadata_2025 huggingface dataset:
On-Line Pre-Hardening Process of Large Plastic Die Steel
Authors: Zhu Dong Mei , Liu Guo Yong , Zhang Shao Jun , Li Mou Wei
Published: March 2013

The thermal parameters of 3Cr2Mo plastic die steel were tested. The temperature fields of 3Cr2Mo plastic die steel with the thickness 120mm were calculated and analyzed under two quenching processes. The results showed that for interrupted process the cooling velocity was faster when the temperature was more than 500°C, which was not in the transformation zone of bainite and martensite. And the fast cooling rate effectively avoided the pearlite appearance. When the temperature was less than 500°C, the cooling velocity under interrupted cooing process was slower, which avoided the big microstructure stress. So for the 3Cr2Mo plastic die steel with the thickness 120mm, the interrupted process was better. In the paper, the hardness was tested after interrupted cooling process and tempering. The tempering hardness difference was less than or equal to 3HRC. The study provided references for large plastic die steel on-line pre-hardening process formulation and optimization.
A Kind of Electrode Printing Screen of Equivalent Elastic Modulus Calculation Method
Authors: Wang Xin Feng , Liao Qing Quan , Xie Fang , Tao Yi
Published: March 2013

Electrode printing screen is an important component in electrode printing manufacturing equipment. Its mechanical properties directly related to printing electrode precision and equipment life, so it is necessary for calculation of mechanics performance analysis. In this paper, by using material mechanics knowledge, the equivalent elastic modulus calculation formula of electrode printing screen is derived and can be applied to mechanical analysis and calculation of electrode printing screen.
Dynamic Analysis of Leveling Mechanism of New Goose-Neck Jib Gondola
Authors: Tao Yi , Guo Jian Feng , Zhou Kai , Wang Xin Feng , Du Xiao Jun
Published: March 2013

In this paper, a virtual prototype has been built for new goose-neck jib gondola with type of CD250 on the basis of ADAMS, and then, the dynamic simulation to the effect of the leveling mechanism is analyzed to obtain the angular velocity curve and angular displacement curve of the basket, which can be regarded as the important evidence to analyze the operation effectiveness of the leveling mechanism of gondola. The approach provides the sufficient theoretical basis for rational design of the structure of gondola as well as product optimization.
Lens Detection Technology and its Machining Allowance Prediction Based on MATLAB
Authors: Zheng Xiu Lian , Zhou Di Feng
Published: March 2013

The detection of lens’ surface smoothness is an important technical problem in the production practice. Through analysis the recognition characteristics of lens, the Newton Ring interference fringe of planoconvex lens is simulated by MATLAB first. Stripe brightness curve is analysis based on improfile function method, and the brightness standard curve of ideal lens system is established. Through comparison the brightness curve produced by Newton Ring of standard lens and the sample, the flatness of the lens surface and defect depth or bump height are assessed. This method is easy to application and has higher adaptability to environment. It provides a new method for the detection of lens’ surface smoothness.
Simulation of Isothermal Nucleation of Austenite in Spheroidite Plain Carbon Steels
Authors: Karacs Gábor , Roósz András
Published: March 2013

The austenitization is a solid phase transformation process accompanied by nucleation and nucleus growth controlled by long-range carbon diffusion. In the course of our work, a method was developed by which spheroidite model structures were constructed such a way that their different parameters (the size of ferrite grains, the average value of carbon concentration, the size of cementite spheroids) could be changed optionally. In addition, a nucleation model of free enthalpy base was created by which the difference between the two different places of nucleation can be distinguished on the basis of their free enthalpy. The effects of structure parameters, interface free enthalpies and temperature on the nucleation rate of austenite were investigated by cellular automaton simulations.
The Effect of Aluminium and Nickel on some Spectral Lines of Alkaline-Earth Metals in the Course of ICP-AES Analysis
Authors: Bánhidi Olivér
Published: March 2013

In this paper a special effect of aluminium and nickel on the spectral lines of alkaline-earth metals being present in low concentration was studied. During the study a sharp difference could be obtained in the behaviour of atomic and ionic lines, therefore among the lines investigated both atomic and ionic ones were included. The effect of Ni and Al was investigated in a wide concentration range in case of Be, Mg, Ca and Sr. In case of each of the four alkaline-earth element a significant difference in the depression of the signal could be observed with increasing Al or Ni concentration among atomic and ion lines.
Optimally Balanced Active-Passive Corrosion Protection by Zinc-Rich Paint Coatings Featuring Proper Hybrid Formulation with Polypyrrole Modified Carbon Nanotubes
Authors: Gergely András , Török Tamas I.
Published: March 2013

Fine balance between active galvanic and passive barrier corrosion protection by zinc-rich hybrid paints is explored depending on the absolute and relative amounts of the electrically semi-conducting particles, viz. polypyrrole (PPy) modified alumina hydrate and multi-walled carbon nanotubes (MWCNTs) and the zinc pigments. The former was varied between 3.21 and 1.75 wt.%, the latter was altered from 70 to 80 wt.% in the primers. The coating with less zinc indicated firm and stable barrier nature in a 254 h immersion test whereas the primer with greater zinc content afforded superior galvanic corrosion prevention in salt-mist test over 142 days. Different nature of the coatings are expounded on the basis of structure and 3D arrangement of the nano-size inhibitor particles in the epoxy vehicle besides interpreted considering varied grain contents caused changing electrical percolation and electrolytic conductivity of the primers.
Limitations in Measuring the Flow Stress
Authors: Krallics György , Reé András , Bobor Kristóf , Szombathelyi Viktor
Published: March 2013

In designing of plastic metalworking technologies, one determining amount used is the flow stress (kf ) of the material to be formed. A few experimental methods are used to measure it, but in all case it is intended to establish a specific stress and strain state in the whole volume of the specimen, or at least in its majority. In our work the limitations of upsetting in axial symmetrical and plane strain states were investigated by FE modeling and experimental methods within cold working conditions. Both methods were executed on traditional testing machines and Gleeble 3800 thermo-mechanical simulator. It was intended to determine the flow stress up to as high strain values as possible. The processing of the experimental results showed, reliable flow stress values were obtainable in the equivalent strain range of 0 to 3 using the step-by-step upsetting in plane strain, and in the 0 to 1.2 range by cylindrical upsetting.
Residual Stress Evolution during Fatigue Test of a Shoot Peened Steel Sample
Authors: Cseh Dávid , Mertinger Valéria , Lukács János
Published: March 2013

Directly-generated compressive residual stress has become a widely used surface modification technique. Intentional residual stress in solid materials can be produced by different surface compression methods. It is well known how residual stress field is influenced by the parameters of inducing technology, but during the operation of a surface compressed machine element the problem of compressive residual stress relaxation can occur. Only few articles address this phenomenon. The literature on residual stress decrease caused by fatigue load is scarce and the kinetics of this mechanism is not yet investigated. The present work reports on the examination of the effect of the fatigue load on compressive residual stress strengthened specimens. Investigations have been conducted at three stress levels. Residual stress data have been measured before fatigue load and measurements have been repeated after defined fatigue cycles.
Grain Boundary Dynamics under an Applied Stress
Authors: Molodov Dmitri A.
Published: March 2013

The response of various structurally different planar grain boundaries in aluminum bicrystals to an applied stress was experimentally investigated. Stress induced boundary migration was observed to be coupled to a tangential translation of the grains for symmetrical and asymmetrical and tilt boundaries with both low and high misorientation angles. The activation enthalpy of high angle boundary migration was found to vary non-monotonously with misorientation angle, whereas for low angle boundaries the migration activation enthalpy was virtually the same. The Σ7 CSL boundaries in bicrystals of different geometry were observed to move under an applied stress, but their migration did not produce shear. These crystallographically equivalent boundaries, however, were found to behave different with respect to migration rate and its temperature dependence. The stress driven migration of the mixed tilt-twist boundary was observed to be accompanied by both the translation of adjacent grains parallel to the boundary plane and their rotation around the boundary plane normal. This behavior was interpreted in terms of the structure of the investigated tilt-twist boundary.
Magnetically Controlled Grain Boundary Motion and Grain Growth in Zinc
Authors: Günster Christoph , Molodov Dmitri A. , Gottstein Günter
Published: March 2013

The motion of grain boundaries in zinc bicrystals (99.995%) driven by the “magnetic” driving force was investigated. Planar symmetrical and asymmetrical tilt grain boundaries with rotation angles in the range between 60° and 90° were examined. At a given temperature the boundary migration rate was found to increase linearly with an applied driving force. The absolute grain boundary mobility was determined. The boundary mobility and its temperature dependence were found to depend on the misorientation angle and the inclination of the boundary plane. An application of a magnetic field during the annealing of cold rolled (90%) Zn-1.1%Al sheet specimens resulted in an asymmetry of the two major texture components. This is interpreted in terms of magnetically affected grain growth kinetics.
Disconnection Motion in Low- and High-Angle Symmetrical Tilt Grain Boundaries in HCP Metal
Authors: Pond Robert C. , Hirth John P. , Khater Hassan A. , Serra Anna
Published: March 2013

The structure of disconnections in symmetrical low- and high-angle [0001] tilt boundaries in an hcp metal are studied using atomic-scale simulation. Applied engineering strains cause such defects to move conservatively along the boundaries, producing coupled shear and migration. The Peierls stresses causing such motion are found to decrease precipitously through the transition from low- to high-angle boundaries. The reason underlying this behaviour is discussed.
Recrystallisation Characteristics of Cold Rolled Austenitic Stainless Steel during Repeated Annealing
Authors: Kumar B. Ravi , Sharma Sailaja
Published: March 2013

The aim of the present study was to understand recrystallisation behaviour of a cold rolled AISI 316L austenitic stainless steel when annealed repetitively for short durations. The results were compared with isothermal annealing process. The evolving microstructure was examined by electron microscope. Electron backscattered diffraction was performed in a FEI NANO SEM 430 Field Emission Gun scanning electron microscope using an EDAX/TSL high-speed Digiview camera for Kikuchi pattern acquisition. Also progress of recrystallisation was assessed by hardness measurements at different annealing conditions. The study revealed distinct differences in the progress of recrystallisation of repeated and isothermally annealed specimens. Also the formation of ultrafine grained microstructure by repeated annealing process was noted.
Effects of Grain Boundaries in Columnar Grained Electrical Steels during Deformation and Recrystallization
Authors: Yang Ping , Shao Yuan Yuan , Zhang Ning , Cheng Ling , Mao Wei Min
Published: March 2013

The crystallographic and topographic anisotropies of columnar grains can exert strong influence on the subsequently hot rolled, cold rolled and annealed microstructures, textures and properties. The single type tilting grain boundaries among columnar grains will behave differently depending on grain orientations, rolling direction and stress state due to hot rolling and thus affect in return the microstructure and texture to some extents. This work aims to reveal the effects of grain boundaries and their neighboring grain orientation gradients in three types of Fe-3Si in differently processed samples using EBSD technique.
Microstructure and Texture Evolution during Recrystallization of a Fe-Mn-C Alloy
Authors: Lu Fa Yun , Haase Christian , Barrales-Mora Luis Antonio , Molodov Dmitri A. , Yang Ping
Published: March 2013

Microstructure and texture evolution of a 60% cold-rolled Fe-22.3Mn-0.3C alloy during annealing at 550°C were studied. Shear bands, triple junctions and grain boundaries were found to be the preferential nucleation sites. The orientations of the nuclei from these sites were found to be mainly random, but also partly located in α-(//ND) and γ-fibers (//ND). After annealing, fine recrystallized grains formed with abundant annealing twins which had a strong impact on the texture development. The final texture was of low intensity and revealed a weak α-fiber.
Influence of Annealing Heating Rate on Nb Ferritic Stainless Steel Microstructure and Texture
Authors: Rodrigues Daniella Gomes , Oliveira Tarcísio Reis , Santos Dogoberto Brandão , Gonzalez Berenice Mendonça
Published: March 2013

The cold rolled band of the niobium stabilized type ASTM 430 ferritic stainless steel with 85 % thickness reduction was annealed with heating rates of 0.10, 6.8, 23.5 and 41.5 °C/s and a soaking time of 24 s. The changes in microstructure and texture were followed by interruptions in the annealing cycle at temperatures of 780, 830 and 880 °C. Annealing at the lower heating rate was more effective for the development of γ-fiber than the annealing performed with high heating rate. The increased rate of heating provided an increase in the onset recrystallization temperature, a reduction in average grain diameter and a more homogeneous distribution throughout the thickness. The specimens with higher volume fraction of the γ-fiber annealed with low heating rate showed a high average coefficient of anisotropy R =1.99.
Continuous and Discontinuous Recrystallization of 6013 Aluminum Alloy
Authors: Sztwiertnia Krzysztof , Bieda Magdalena , Korneva Anna
Published: March 2013

In situ orientation mapping using TEM and calorimetric measurements were carried out to investigate the annealing behavior of cold-rolled 6013 aluminum alloy. The recrystallization of the material can be considered to be a number of processes that correspond to two separate stored energy release peaks. In the temperature range of the peak 1, the deformation zones around the large second-phase particles acted as sites for particle-stimulated nucleation. In the matrix, at the same time, some elongation of grains occurred. The elongated matrix grains appeared because of the reduction of the dislocation density and the annihilation of some low-angle grain boundaries between chains of subgrains lying in layers parallel to the sheet plane. The matrix processes in this temperatures range can be considered forms of continuous recrystallization. The matrix high-angle grain boundaries started to migrate at the temperature range of the peak 2. They moved mostly in the direction normal to the sheet plane. Heating of the sample for an appropriate time at those temperatures resulted in the complete discontinuous recrystallization of the material. The recrystallized microstructure was dominated now by elongated grains, which were a few times thicker than those obtained by annealing at the temperatures of the peak 1.
EBSD Investigation of Cold Rolled and Recrystallized Titanium
Authors: Jedrychowski Mariusz , Tarasiuk Jacek , Bacroix Brigitte
Published: March 2013

EBSD investigation of texture and microstructure evolution during a complete thermomechanical treatment of commercially pure titanium (HCP-Ti) is presented. Titanium was cold rolled to reach various degrees of thickness reduction: 20%, 40% and 60%. Next, annealing in air atmosphere was conducted at different conditions to achieve the recrystallized state. EBSD topological maps were measured on RD-TD and RD-ND surface of each sample. Strong heterogeneity of deformed titanium microstructures is described with focus on the important role of twinning mechanisms. Texture evolution in investigated titanium appears to be limited, especially in recrystallized state. However some subtle mechanisms are discussed.
Abnormal Grain Growth in Ferritic-Martensitic Eurofer-97 Steel
Authors: de Oliveira Verona Biancardi , Padilha Angelo Fernando , Möslang Anton , Raabe Dierk , Sandim Hugo Ricardo Zschommler
Published: March 2013

Abstract. Ferritic-martensitic steels like Eurofer-97 are candidate structural materials for future fusion reactors. In the tempered state, this steel contains fine particles dispersed in the ferritic matrix. The aim of this work is to investigate abnormal grain growth in Eurofer-97 steel. The microstructural evolution was followed by isothermal annealing between 200 and 800°C (ferritic phase field) after cold rolling to 70, 80, and 90% reductions. Representative samples were characterized by scanning electron microscopy in the backscattered electron mode. Microtexture was evaluated by electron backscattered diffraction. We propose a mechanism based on the size advantage acquired by nuclei with misorientation angles above 45º relative to their nearest neighbors to explain abnormal grain growth. Abnormal grain growth textures have components belonging to the α- and γ-fibers with predominance of {111}, {111}, and {100}.
Orientation Selectivity of Secondary Recrystallization in Grain-Oriented Silicon Steel
Authors: Ushigami Yoshiyuki , Arita Yoshihiro , Ushioda Kohsaku
Published: March 2013

It has been observed that grain size of Goss secondary grain has a strong correlation with deviation angle from the exact Goss orientation and sharper Goss grain has larger grain diameter. This orientation selectivity of secondary recrystallization has been investigated with the statistical model of grain growth in which inhibitor and texture are taken into account. The model assumes that sharper Goss grain has a higher frequency of CSL boundaries to the matrix grains and thus has lower statistical grain boundary energy and suffers lower pinning force from the inhibitor. The analysis showed that this model successfully explains orientation selectivity and depicts the effect of inhibitor and texture.
Grain Growth in Nb-Alloyed Stainless Steel of AISI 347 during Heating
Authors: Luo Hai Wen , Dong Han , Chen Ling Feng
Published: March 2013

Grain growth kinetics in an AISI 347 stainless steel with Nb content up to 0.7%wt was studied during the isothermal holding in the temperature range of 1100-1270°C for various periods. Abnormal grain growth was observed even in the presence of a large amount of precipitates. The kinetics of normal grain growth was tracked by metallographic measurements and fitted by the classical modeling, which led to two important parameters of activation energy Q and growth exponent n derived. Both of them are larger than the usual values for grain growth in the Nb-microalloyed steels due to the much larger content of Nb in the present steel.
Coupled Grain Growth and Precipitation Modeling in Multi-Phase Systems
Authors: Rath Markus , Kozeschnik Ernst
Published: March 2013

In this work, we utilize recent software for precipitation kinetics simulation and couple it with models for grain growth. Basis of our studies is the thermo-kinetic software MatCalc, which has been designed for simulation of the evolution of precipitates in general multi-component multi-phase alloy systems. Grain growth approaches of different complexity are incorporated into the precipitation kinetics framework, investigated with respect to their coupling behavior with precipitation and precipitate dissolution and, finally, benchmarked on typical grain growth problems of industrial practice. The example presented in this work comprises austenite grain growth studies accompanying TiN and NbC precipitation/dissolution during austenitization of a Ti/Nb microalloyed steel. It is demonstrated that the present approach represents a versatile tool for analysis of simultaneous grain growth and precipitation in industrially important alloy systems.
3-D Topological Relationships and Von Neuman-Type Equation
Authors: Abbruzzese Giuseppe Carlo
Published: March 2013

Based on a 3-D Von Neumann equation a general theoretical formulation has been provided in the framework of the statistical theory of grain growth to predict the microstructure evolution. By the same approach the topological relationships between number of grain faces, grain size, number of corners and edges and how these can be calculated in a real microstructure with a statistical approach are discussed. A quadratic law for the linkage between number of faces and grain size is found and together with the functional dependency of other relevant 3-D microstructure parameters good agreement with available experimental results is found .
Recrystallization of 304SS during and after High Strain Rate Deformation
Authors: Taylor Adam S. , Hodgson Peter
Published: March 2013

During the hot working of austenitic stainless steels the shape of the flow curve is strongly influenced by the strain rate. Low strain rate deformation results in flow curves typical of dynamic recrystallization (DRX) but as the strain rate increases the shape changes to a ‘flat-top’ curve. This has traditionally been thought to indicate no DRX is taking place and that dynamic recovery (DRV) is the only operating softening mechanism. Examining the work-hardening behaviour and corresponding deformation microstructures showed this is not the case for austenitic stainless steel, as clear evidence of dynamic recrystallization process can be seen. The post-deformation recrystallization kinetics can be modelled using a standard Avrami equation with an Avrami exponent, n, of 1.15. With an increasing value of the Zener-Hollomon parameter it was found that the kinetics of recrystallization become less strain rate sensitive until at the highest values (highest strain rates/lowest temperatures) the recrystallization kinetics become strain rate insensitive.
Novel Approach to Model Static Recrystallization of Austenite during Hot-Rolling of Nb-Microalloyed Steel: Effect of Precipitates
Authors: Rehman Kashif , Zurob Hatem
Published: March 2013

Microalloying additions are critical for grain size control during thermo-mechanical processing. The addition of niobium is known to delay the onset and growth of recrystallization. A physically-based model for the interaction of strain-induced precipitation, recovery and recrystallization is presented. A key feature of the model is the incorporation of the effect of precipitation on the nucleation of recrystallization. Quantitative agreement between the experimental measurements and the model predictions has also been demonstrated. The model offers valuable insight into the relative contributions of solute and precipitate Nb as well as the optimum conditions for strain accumulation.
Evolution of Microstructure during Hot Deformation of Pearlitic Steel
Authors: Sabat Rama Krushna , Hatwal Sajal , Dixit Bharath , Suwas Satyam
Published: March 2013

Hot deformation of pearlitic steel was carried out to examine the overall deformation response to micro structural and texture evolution. To understand the mechanisms operative during hot deformation, compression tests were carried out at various temperatures in the range 400 - 600o C and strain rates in the range 0.001-10 s-1. The flow curves were analyzed to examine the occurrence of dynamic recrystallization. The evolution of microstructure and texture of hot deformed sample is analysed using EBSD and X-ray texture goniometer respectively.
Strength and Formability of Fine-Grained Laminated Magnesium Alloy
Authors: Noda Masafumi , Funami Kunio
Published: March 2013

The development of laminated composite Mg alloy sheets, prepared by solid diffusion and roll bonding, is an effective way of improving the stiffness and surface properties of these materials while retaining their lightness. Laminated composites consisting of a core of Mg alloy between sheets of A5083 alloy as the coating material with Ti foil interlayers were prepared by solid diffusion and roll bonding. The laminated material had a strength and was resistant to cracking during deformation. Compounds that were formed and dispersed at the bonding interface between the Al and Mg alloys subjected to grain refinement improved the fracture toughness and strength of the composites, and it was important that these compounds were formed discontinuously. The fracture toughness of the laminated composite was twice that of the base Mg alloy, and its Young's modulus was 57 GPa.
Nanocrystalline Twinning Induced Plasticity Steel with Superior Mechanical Properties Fabricated by Cold Rolling and Annealing
Authors: Saha Rajib , Ueji Rintaro , Tsuji Nobuhiro
Published: March 2013

A study has been carried out on the evolution of microstructure, grain boundary character and mechanical properties in a Twinning Induced Plasticity steel heavily cold rolled and subsequently annealed.The cold rolled mcrostructures showed fine lamellar boundaries with many shear bands.With progress of annealing, numerous numbers of recrystallized grains were generated.The fully recrystallized steel showed equi-axed nanocrystalline grains with a mean grain size of 400 nm that enhanced the yield strength significantly while retaining tensile ductility.
Effect of Inter-Pass Ageing during Cold Rolling on Magnetic Properties of Fe-3%Si
Authors: Amorim Dirceni Souza Costa , Cunha Marco Antônio , Santos Dogoberto Brandão , Brandão João Henrique , Gonzalez Berenice Mendonça
Published: March 2013

The effects of inter-pass ageing temperature during cold rolling on structure, magnetic properties and mechanical properties of high permeability grain oriented electrical steel was studied. The samples were processed in a single-stage cold rolling to 0.27 mm thickness, with 88 % reduction, without and with inter-pass ageing treatment in order to determine the magnetic properties. To determine the changes in mechanical properties due to strain ageing, the samples underwent overlapped ageing, after pre-strain by rolling, under the same conditions of inter-pass ageing and then were subjected to tensile test. The effect of strain ageing was more pronounced in the thickness of 0.7 mm and the largest variation in yield strength was at 200°C in all evaluated thicknesses. At this temperature the largest amount of {110} orientation after primary recrystallization was also observed, as well as the lowest final grain size and consequently the best results of core loss. The magnetic induction had almost no alterations.
Effect of Austenite Recrystallization on Toughness of Pipeline Steels
Authors: Jonas John Joseph
Published: March 2013

The factors affecting pipeline fractures are reviewed briefly, with particular emphasis on the influence of the {100} texture component. The deformation texture components introduced by rolling in the austenite temperature range are introduced, together with the component changes associated with recrystallization. The effect of the γ-to-α phase transformation on the austenite deformation and recrystallization texture components is described. The changes to the texture brought about by rolling in the ferrite (or in the intercritical) phase field are also outlined. The controlled rolling parameters that promote minimization of the texture intensity of the deleterious {100} component are summarized.
Microstructure and Properties of Ultrafast Annealed High Strength Steel
Authors: Petrov Roumen , Hajyakbari Farideh , Saz Fernando Ramos , Sidor Jurij , Santofimia Maria Jesus , Sietsma Jilt , Kestens Leo A.I.
Published: March 2013

The grain size, recrystallization, phase transformation and mechanical properties of a cold-rolled high-strength steel (HSS) are studied after annealing with high (~140°C/s) and ultra-high (~1500°C/s) reheating rate, followed by subsequent water quenching without isothermal soaking. By monitoring the hardness and microstructure, it was shown that the increase of the reheating rate from 140°C/s to 1500°C/s causes grain refinement from 5 µm to 1 µm in diameter and the final ferrite grain size depends significantly on the reheating temperature and reheating rate. It was observed that after an extreme reheating rate of ~1500°C/s the α-γ phase transformation starts before the completion of recrystallization in the recovered matrix. The crystallographic texture of the ultrafast reheated and water-quenched high-strength steel inherits the cold-rolled deformation texture with well pronounced RD and ND texture fibres, even after the α-γ-α′ phase transformations. It was found that the ultrafast reheating results in a very fine non-equilibrium ferrite-martensite structure with an excellent ultimate tensile strength of ~1400 MPa and an acceptable elongation at fracture. The observed data are very promising from industrial application point of view and open up possibilities for further structural refinement and alternative texture control.
An Alternative Method of Grain Boundary Characterization
Authors: Jedrychowski Mariusz , Tarasiuk Jacek , Bacroix Brigitte , Wroński Sebastian
Published: March 2013

EBSD (Electron Backscatter Diffraction) is a modern experimental technique which allows to represent the information about texture and microstructure in the form of a topological map comprised of a very large number of acquisitioned orientation points. Such a map can be easily used to analyze grain boundaries. In TSL OIM Data Analysis software it is mainly done by Line Segments Method, in which grain boundaries are represented as lines separating pairs of EBSD points for which the misorientation value is within a specified range. The aim of this work is to present a complementary method of grain boundary characterization. In this case, a GB consists of specially selected EBSD points and is thus represented as a two dimensional area. As a result, new possibilities of GB analysis emerge, such as texture of GB areas. The provided description may be also more compatible with a real microstructure, especially after deformation, in which grain boundaries (especially the one with small misorientation) are indeed areas of lattice defects accumulation.
Murine NK Cell Intrinsic Cytokine-Induced Memory-like Responses Are Maintained following Homeostatic Proliferation
Authors: Keppel Molly P. , Yang Liping , Cooper Megan A.
Published: March 2013

Several recent studies have demonstrated that innate immune NK cells exhibit memory-like properties with enhanced nonspecific and specific recall responses. Cytokine activation alone of murine NK cells induces the differentiation of memory-like cells that are more likely to produce IFN-γ, a key NK cell cytokine important for activation of the immune response. Using an adoptive cotransfer system, we first show that cytokine-induced memory-like responses are NK intrinsic. However, engraftment of donor NK cells in NK-competent hosts is poor because of homeostatic control mechanisms. Therefore, we used alymphoid Rag- and common γ-chain–deficient mice as recipients and observed homeostatic expansion of cotransferred cytokine-activated and control donor NK cells. Despite proliferation of all cells, NK cells derived from those cells originally activated by cytokines retained an intrinsic enhanced capacity to produce IFN-γ when restimulated in vitro with cytokines or target cells. These NK cell memory-like responses persisted for at least 4 wk in alymphoid hosts and 12 wk in NK-competent hosts. These findings indicate that memory-like NK cells can readily self-renew and maintain enhanced function in a lymphopenic host for at least a month.
Adiponectin Deficiency Suppresses Lymphoma Growth in Mice by Modulating NK Cells, CD8 T Cells, and Myeloid-Derived Suppressor Cells
Authors: Han Sora , Jeong Ae Lee , Lee Sunyi , Park Jeong Su , Kim Kwang Dong , Choi Inpyo , Yoon Suk Ran , Lee Myung Sok , Lim Jong-Seok , Han Seung Hyun , Yoon Do Young , Yang Young
Published: March 2013

Previously, we found that adiponectin (APN) suppresses IL-2–induced NK cell activation by downregulating the expression of the IFN-γ–inducible TNF-related apoptosis-inducing ligand and Fas ligand. Although the antitumor function of APN has been reported in several types of solid tumors, with few controversial results, no lymphoma studies have been conducted. In this study, we assessed the role of APN in immune cell function, including NK cells, CTLs, and myeloid-derived suppressor cells, in EL4 and B16F10 tumor-bearing APN knockout (KO) mice. We observed attenuated EL4 growth in the APNKO mice. Increased numbers of splenic NK cells and splenic CTLs were identified under naive conditions and EL4-challenged conditions, respectively. In APNKO mice, splenic NK cells showed enhanced cytotoxicity with and without IL-2 stimulation. Additionally, there were decreased levels of myeloid-derived suppressor cell accumulation in the EL4-bearing APNKO mice. Enforced MHC class I expression on B16F10 cells led to attenuated growth of these tumors in APNKO mice. Thus, our results suggest that EL4 regression in APNKO mice is not only due to an enhanced antitumor immune response but also to a high level of MHC class I expression.
Normal Dendritic Cell Mobilization to Lymph Nodes under Conditions of Severe Lymphatic Hypoplasia
Authors: Platt Andrew M. , Rutkowski Joseph M. , Martel Catherine , Kuan Emma L. , Ivanov Stoyan , Swartz Melody A. , Randolph Gwendalyn J.
Published: March 2013

To address the requirement for lymphatic capillaries in dendritic cell (DC) mobilization from skin to lymph nodes (LNs), we used mice bearing one inactivated allele of vascular endothelial growth factor receptor 3 (VEGFR3) where skin lymphatic capillaries are reported absent. Unexpectedly, DC mobilization from the back skin to draining LNs was similar in magnitude, and kinetics to control mice and humoral immunity appeared intact. By contrast, DC migration from body extremities, including ear and forepaws, was ablated. An evaluation in different regions of skin revealed rare patches of lymphatic capillaries only in body trunk areas where migration was intact. That is, whereas the ear skin was totally devoid of lymphatic capillaries, residual capillaries in the back skin were present though retained only at ∼10% normal density. This reduction in density markedly reduced the clearance of soluble tracers, indicating that normal cell migration was spared under conditions when lymphatic transport function was poor. Residual lymphatic capillaries expressed slightly higher levels of CCL21 and migration of skin DCs to LNs remained dependent on CCR7 in Chy mice. DC migration from the ear could be rescued by the introduction of a limited number of lymphatic capillaries through skin transplantation. Thus, the development of lymphatic capillaries in the skin of body extremities was more severely impacted by a mutant copy of VEGFR3 than trunk skin, but lymphatic transport function was markedly reduced throughout the skin, demonstrating that even under conditions when a marked loss in lymphatic capillary density reduces lymph transport, DC migration from skin to LNs remains normal.
Transition from Heterotypic to Homotypic PDK1 Homodimerization Is Essential for TCR-Mediated NF-κB Activation
Authors: Kang Jung-Ah , Jeong Sang Phil , Park Daeho , Hayden Matthew S. , Ghosh Sankar , Park Sung-Gyoo
Published: March 2013

Strong NF-κB activation requires ligation of both the CD28 coreceptor and TCR. Phosphoinositide-dependent kinase 1 (PDK1) acts as a scaffold by binding both protein kinase Cθ (PKCθ) and CARMA1, and is therefore essential for signaling to NF-κB. In this article, we demonstrate the importance of PDK1 Thr513 phosphorylation in regulating the intermolecular organization of PDK1 homodimers. Thr513 is directly involved in heterotypic PDK1 homodimer formation, in which binding is mediated through the pleckstrin homology (PH) and kinase domains. Upon activation, phosphorylated Thr513 instead mediates homotypic intermolecular binding through the PH domains. Consequently, cell-permeable peptides with a Thr513 to Ile derivative (protein transduction domain [PTD]-PDK1-Thr513-Ile) bound the kinase domain, whereas a Thr513-to-Asp peptide (PTD-PDK1-Thr513-Asp) bound the PH domain. PTD-PDK1-Thr513-Ile blocked binding between PDK1 and PKCθ, phosphorylation of PKCθ Thr538, and activation of both NF-κB and AKT. In contrast, PTD-PDK1- Thr513-Asp selectively inhibited binding between PDK1 and CARMA1, and blocked TCR/CD28-induced NF-κB activation. Therefore, Thr513 phosphorylation regulates a critical intermolecular switch governing PDK1 homodimer structure and the capacity to interact with downstream signaling pathway components. Given the pleiotropic functions of PDK1, these data may open the door to the development of immunosuppressive therapies that selectively target the PDK1 to NF-κB pathway in T cell activation.
Malignant mesotheliomas in spermatic cords: reports of two cases and a brief review of literature
Authors: Meng Xianmin , Guzzo Thomas J. , Bing Zhanyong
Published: March 2013

Primary malignant mesothelioma (MM) of spermatic cord is extremely rare. We presented two malignant mesotheliomas involving the spermatic cords; one was primary, one secondary. The secondary one represented the direct involvement by a peritoneal MM. No occupational exposure to asbestos was identified in either patient. Both of them presented with a painless inguinal mass. Microscopically the primary MM was epithelioid type with tumor nests infiltrating adjacent adipose tissue, while the secondary MM grew in mixed type. No tumor necrosis was seen in the primary MM, while extensive necrosis was seen in the secondary one. Rare mitotic figure was seen in the primary MM while the mitosis in the secondary tumor was brisk, and with atypical mitosis. Immunohistochemically the tumor cells were positive for calretinin and CK5/6 and negative for BER-EP4 and BRST3 in both cases. The reported cases of primary MM from spermatic cord in English literature were briefly reviewed.
New Sylvatic Hosts of Trypanosoma cruzi and Their Reservoir Competence in the Humid Chaco of Argentina: A Longitudinal Study
Authors: Orozco M. Marcela , Enriquez Gustavo F. , Alvarado-Otegui Julián A. , Cardinal M. Victoria , Schijman Alejandro G. , Kitron Uriel , Gürtler Ricardo E.
Published: March 2013

A four-year longitudinal study of the structure of sylvatic transmission cycles of Trypanosoma cruzi, reservoir host competence and parasite discrete typing units was conducted in a disturbed rural area of the humid Chaco in Argentina. Among 190 mammals examined by xenodiagnosis and polymerase chain reaction amplification, the composite prevalence of infection was substantially higher in Dasypus novemcinctus armadillos (57.7%) and Didelphis albiventris opossums (38.1%) than in Euphractus sexcinctus (20.0%), Tolypeutes matacus (12.5%), and Chaetophractus vellerosus (6.3%) armadillos. Trypanosoma cruzi was detected for the first time in Thylamys pusilla small opossums and in two unidentified small rodents. Infection was spatially aggregated only in armadillos. All Didelphis were infected with T. cruzi I and all armadillo species were infected with T. cruzi III, implying two distinct sylvatic cycles with no inputs from the domestic cycle. Dasypus armadillos and Didelphis opossums were much more infectious to vectors than other armadillos, small opossums, or rodents.
Molecular Diagnosis of Schistosoma Infections in Urine Samples of School Children in Ghana
Authors: Aryeetey Yvonne A. , Essien-Baidoo Samuel , Larbi Irene A. , Ahmed Kwaku , Amoah Abena S. , Obeng Benedicta B. , van Lieshout Lisette , Yazdanbakhsh Maria , Boakye Daniel A. , Verweij Jaco J.
Published: March 2013

Recent studies using an internal transcribed spacer (ITS)-based real-time polymerase chain reaction (PCR) for the detection of Schistosoma DNA in urine samples has shown high sensitivity and specificity when performed on controls and known microscopy-positive samples. In this study, using 730 urine samples collected from children in five primary schools from different communities in the Greater Accra region of Ghana, specific detection of Schistosoma DNA showed excellent sensitivity of 100% and 85.2% in urines with > 50 eggs/10 mL urine and ≤ 50 eggs/10 mL of urine, respectively. Additionally, Schistosoma-specific DNA was amplified in 102 of 673 samples in which Schistosoma eggs could not be detected with microscopy. Taking microscopy and/or PCR-positive samples as true positives, the negative predictive value calculated was 94.6–100% for each school sampled as compared with 54.3–95.7% using microscopy. This ITS-based real-time PCR proves to be a powerful tool in epidemiological surveys of schistosomiasis providing more precise and sensitive results than microscopy.
Photochemical Inactivation of Chikungunya Virus in Human Apheresis Platelet Components by Amotosalen and UVA Light
Authors: Tsetsarkin Konstantin A. , Sampson-Johannes Adam , Sawyer Lynette , Kinsey John , Higgs Stephen , Vanlandingham Dana L.
Published: March 2013

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that recently re-emerged in Africa and rapidly spread into countries of the Indian Ocean basin and South-East Asia. The mean viremic blood donation risk for CHIKV on La Réunion reached 1.5% at the height of the 2005–2006 outbreaks, highlighting the need for development of safety measures to prevent transfusion-transmitted infections. We describe successful inactivation of CHIKV in human platelets and plasma using photochemical treatment with amotosalen and long wavelength UVA illumination. Platelet components in additive solution and plasma units were inoculated with two different strains of high titer CHIKV stock (6.0–8.0 logs/mL), and then treated with amotosalen and exposure to 1.0–3.0 J/cm2 UVA. Based on in vitro assays of infectious virus pre- and post-treatment to identify endpoint dilutions where virus was not detectable, mean viral titers could effectively be reduced by > 6.4 ± 0.6 log10 TCID50/mL in platelets and ≥ 7.6 ± 1.4 logs in plasma, indicating this treatment has the capacity to prevent CHIKV transmission in human blood components collected from infected donors in or traveling from areas of CHIKV transmission.
A Comparison of the Kampala Trauma Score with the Revised Trauma Score in a Cohort of Colombian Trauma Patients
Authors: Clarkson Colin A , Clarkson Cain , Rubiano Andres M , Borgaonkar Mark
Published: March 2013

Introduction

To date, no trauma scoring system has emerged as the gold standard for use in developing countries, where limited resources for data collection are a major issue. The purpose of this study is to compare the relatively recently developed and simply calculated KTS (Kampala Trauma Score) with the more widely used RTS (Revised Trauma Score) within a cohort of Colombian trauma patients.

Materials and methods

Data on over 2,200 patients was derived from a newly developed trauma registry in Colombia. A statistical analysis was done using SPSS software, and included simple linear and logistical regression as appropriate.

Results

Both the KTS and RTS were statistically significant in terms of their ability to predict death and length of stay in hospital with the KTS being a better predictor of both. The simplest model predicting death used only the neurologic component of the KTS. However, none of these three scores explained a very large amount of the variation in the dataset.

Conclusion

Although statistically significant, neither the KTS nor the RTS performed well at predicting death or length of hospital stay. However, the simpler KTS did perform somewhat better than the slightly more complex RTS. Using the extremely simple neurologic component of the KTS on its own proved to be the best predictor of length of hospital stay, and also outperformed the RTS in regards to death prediction. It is clear from this study that the optimal injury scoring system for use in under resourced environments remains allusive with further research warranted.

How to cite this article

Clarkson CA, Clarkson C, Rubiano AM, Borgaonkar M. A Comparison of the Kampala Trauma Score with the Revised Trauma Score in a Cohort of Colombian Trauma Patients. Panam J Trauma Critical Care Emerg Surg 2012;1(3):146-149.
Sensibilidad del Eco Doppler en el Trauma Vascular de Miembros Inferiores. Experiencia en el Hospital ‘Dr Domingo Luciani’
Authors: Nuñez Carlos , Cabrera Edward , Torres Patricia , Cova Tamarys , Castro Omar
Published: March 2013

Objetivo general

Determinar la sensibilidad del Eco Doppler en las lesiones vasculares por trauma de miembros inferiores en pacientes ingresados con esta impresión diagnóstica en el Hospital Dr Domingo Luciani durante el período Abril 2008-Diciembre 2011.

Objetivos específicos

Determinar Grupo etario y sexo del paciente con lesión vascular. Definir el mecanismo de trauma de los pacientes sometidos a Eco Doppler por lesión vascular. Mencionar los hallazgos ecográficos de los pacientes ingresados con lesión vascular. Conocer la lesión vascular más frecuente. Precisar los hallazgos quirúrgicos de los pacientes sometidos a Eco doppler por lesión vascular. Correlacionar los hallazgos quirúrgicos con los ecográficos.

Método de investigación

Estudio retrospectivo, descriptivo. Basado en la base de datos de la Unidad de Politraumatizados y en los Servicios de Cirugía General del hospital ‘Dr Domingo Luciani’. Lapso 2008-2011.

Criterios de inclusión

Paciente mayor de 18 años con impresión diagnóstica de lesión vascular de miembros inferiores por trauma. Eco Doppler realizado por las mismas residentes del Servicio de Radiodiagnóstico del Hospital.

Criterios de exclusión

Pacientes con lesión vascular de miembros superiores. Pacientes hemodinámicamenteinestables. Eco Doppler realizado por residentes del Servicio de Radiodiagnósticos no incluidos en la investigación.