Residual Micro Research Articles

Abstract GS02-02: Are nodal ITCs after neoadjuvant chemotherapy an indication for axillary dissection? The OPBC05/EUBREAST-14R/ICARO study

Abstract GS02-02: Are nodal ITCs after neoadjuvant chemotherapy an indication for axillary dissection? The OPBC05/EUBREAST-14R/ICARO study

Residual strain investigation of a polycrystalline quartzite rock sample using time-of-flight neutron diffraction

In this work, we studied the residual micro lattice strain of an onyx sample, which is a micro- to the cryptocrystalline variety of the mineral quartz SiO2. That the investigation has been carried out using in-situ stress experiments with the time-of-flight neutron diffraction method. The aim of the study is to investigate residual lattice strains and pressure directions in the sample using time-of-flight neutron diffraction, which is a powerful tool for the study of the residual strain behavior in bulk materials, like geological rock samples containing large grains. The residual strain was detected in different sample directions turning the sample in steps of 30° by 180° around the cylindrical z-axis. These experiments have been performed at the time-of-flight neutron strain diffractometer EPSILON, situated on the pulsed neutron source IBR-2M of the Joint Institute for Nuclear Research in Dubna, Russia. The results of this study will provide insights into the compressional and tensional residual strain of the crystallographic lattice planes, and will have implications for our understanding of the tectonic history of this region. These different strains are arranged in the sample by a sinusoidal distribution in radial directions.

Mitigating Inhomogeneity and Tailoring the Microstructure of Selective Laser Melted Titanium Orthorhombic Alloy by Heat Treatment, Hot Isostatic Pressing, and Multiple Laser Exposures.

Titanium orthorhombic alloys based on intermetallic Ti2AlNb-phase are attractive materials for lightweight high-temperature applications. However, conventional manufacturing of Ti2AlNb-based alloys is costly and labor-consuming. Additive Manufacturing is an attractive way of producing parts from Ti2AlNb-based alloys. High-temperature substrate preheating during Selective Laser Melting is required to obtain crack-free intermetallic alloys. Due to the nature of substrate preheating, the temperature profile along the build height might be uneven leading to inhomogeneous microstructure and defects. The microstructural homogeneity of the alloy along the build direction was evaluated. The feasibility of mitigating the microstructural inhomogeneity was investigated by fabricating Ti2AlNb-alloy samples with graded microstructure and subjecting them to annealing. Hot isostatic pressing allowed us to achieve a homogeneous microstructure, eliminate residual micro defects, and improve mechanical properties with tensile strength reaching 1027 MPa and 860 MPa at room temperature and 650 °C, correspondingly. Annealing of the microstructurally graded alloy at 1050 °C allowed us to obtain a homogeneous B2 + O microstructure with a uniform microhardness distribution. The results of the study showed that the microstructural inhomogeneity of the titanium orthorhombic alloy obtained by SLM can be mitigated by annealing or hot isostatic pressing. Additionally, it was shown that by applying multiple-laser exposure for processing each layer it is possible to locally tailor the phase volume and morphology and achieve microstructure and properties similar to the Ti2AlNb-alloy obtained at higher preheating temperatures.

Valuation of the environmental benefits induced by a constructed wetland

Under the Water Framework Directive, France needs to work harder to reduce water pollution and has been recommended a more frequent recourse to ecological restoration. Constructed wetlands are particularly interesting as they simultaneously improve water quality, contribute to flood protection and promote biodiversity. In this perspective, the researchers of Lyonnaise des Eaux developed the concept of “Libellule” Zone that aimed at creating a biodiversity area that facilitates the removal of residual micro pollutants from wastewater before it is released into the wild. These actions are clearly beneficial to the environment. Unfortunately, this value remains difficult to estimate even today which can constitute a significant obstacle both to the development of this type of action and to their durability. Our aim is to use the “adapted” Habitat Evaluation Procedure (HEPa) to better value these actions. The HEPa bases the evaluation of environmental costs and benefits directly on the ecological impact of the actions carried out. Our main result is that the HEPa method, initially developed to assess environmental costs, can be a useful method to evaluate the benefits stemming from the creation of an artificial wetland. We expect this evaluation to help decision makers to base their decisions on the true value of wetlands.

A comparative study on mechanical properties of Ti–6Al–4V alloy processed by additive manufacturing vs. traditional processing

The unique thermal history of different metal additive manufacturing processes would have profound impacts on the resulting microstructure and material properties. However, few have conducted benchmark research on the impacts. This work provides a comprehensive benchmark comparison on microstructure, mechanical properties, and their underlying mechanisms in selective laser melting (SLM), electron beam melting (EBM), and mill-annealing of Ti–6Al–4V alloys. The results have shown that the SLMed and EBMed samples possess very fine acicular α′ martensite while the conventional mill-annealed ones have granular α phase. The SLMed samples exhibit the highest tensile and yield strength resulted from the combined effects of refined α’ martensite and high microscale residual stress. The lowest tensile and yield strength and intermediate elongation of the EBMed samples are attributed to the relatively high number of type-II pores and in-situ annealing for residual stress relief during the printing process. The mill-annealed samples have the highest elongation due to the fully dense structure, the negligible microscale residual stress, and favorable grain orientation. It is expected to improve the ductility of SLMed samples via appropriate post-annealing and enhance the strength of EBMed samples by reducing the number of type-II pores through process optimization. The fundamental differences in microstructure and properties are attributed to the unique thermal histories of the concerned processes. • EBMed samples possess more type- II pores and uncertain mechanical properties. • SLMed samples have the highest strength due to refined α′ and residual micro stress. • Mill-annealed have the largest elongation due to dense structure and favorable texture.

Anisotropic Multiscale Modelling in SAE-AISI 1524 Gas Tungsten Arc Welded Joints

A transient non-linear multiscale finite element heat flow-mechanical model to determine micro residual stresses (type III) and micro plastic strains in SAE-AISI 1524 gas tungsten arc welded joints is developed. To include anisotropy by preferred crystallographic orientation or texture, the global domain was decomposed into small subdomains based on the concept of representative volume elements (RVEs). A three-dimensional numerical procedure was developed by using the coupling DREAM.3D-ABAQUS. The macro scale temperature gradient information as prescribed driven (load) boundary conditions was used to calculate the meso thermal cycles, and the meso scale temperature gradient information was used to calculate the micro thermal cycles needed in the subsequent mechanical analysis. Anisotropy was included by randomly entering in each grain of the RVE specimen either the maximum Young’s modulus (Emax) in the stiffest direction <111>, or the minimum Young’s modulus (Emin) in the least stiff direction <100>. Under this assumption, the averaging of the grain orientations over all grains in the textured polycrystal with greater number of grains ocurred, and the strength was diluted by the spread of orientations present. Higher Mises stresses evolved in the sample with coarse grain size (16 µm), which indicates that the strong dependence of residual micro stresses on grain size was reversed. The influence of the grain size on the response of the aggregates is clearly observed.

Comparison of Magnetic Parameters of Quenched Pipe Steels with X-Ray–Evaluated Residual Macro- and Microstresses

Residual micro- and macrostresses have been determined by X-ray diffraction analysis in 22KhG2A, 30KhMA, and 32G2 grade steels quenched and tempered from various temperatures. It is demonstrated that not only residual macrostresses need to be determined, as prescribed by existing regulatory documents, but also microstresses, which characterize the extreme values of residual stresses. The possibility of using magnetic parameters for evaluating residual micro- and macrostresses has been investigated. It has been established that coercive force, maximum magnetic permeability, and Barkhausen magnetic noise characteristics can be used as informative parameters in the evaluation of microstresses.

Residual micro organic pollutants and their biotoxicity of the effluent from the typical textile wastewater treatment plants at Pearl River Delta

This work investigated the biotoxicity and the residual dissolved organic matter (DOM) of the effluents from nine typical full-scale textile plants located at Pearl River Delta (PRD) in Guangdong province, China. The fluorescence regional integration (FRI) analysis showed that the tryptophan-like (II), soluble microbial product-like (IV) and fulvic acid-like substances (III) were the dominant compounds in the DOM. The acute toxicity test showed toxic effects still remained in most textile effluents, which might attribute to the undegraded dyes or aromatic compounds. Combining with the results from multiple methods, it indicated that the selected nine textile wastewater treatment plants (tWWTPs) all contained some residual micro organic pollutants in their effluents, and the residual benzene-derived products or aromatic amines were probably the toxicity-causing substances. Both ozonization and membrane filtration were capable of further decreasing the content of residual DOM, but by comprehensively considering the effects of removing DOM and biotoxicity, membrane filtration was better than ozonization.

Biomaterials for hip implants – important considerations relating to the choice of materials

Abstract This article is a review of important material requirements for hip biomaterials including their response to the body environment (biocompatibility), mechanical properties, wear resistance, fretting corrosion and availability as well as the price. The application of proper biomaterials for hip implants is one of the major focal points in this article. Background information is also provided on metals used in other prosthetic devices and implant components. Titanium and its alloys, cobalt base alloys and stainless steels (bio-steels) are used for load-bearing hip implants. These three groups of metallic materials will be introduced and discussed in detail. Metals and their alloys are crystalline materials since their properties depend on the crystal lattice, chemical and phase compositions, grain size, lattice defects, crystalline texture and residual micro- and macro-stresses. All these features of biomaterials are formed during technological manufacturing, such as metallurgical process, solidification, plastic deformation (rolling and forging), machining, heat treatment and coating. All these technological processes work in optimal conditions in order to achieve the optimal microstructure and mechanical, chemical and biological properties. Amongst the above-mentioned particular properties of biomaterials, fretting is a major concern as regards hip implants at the femoral head and neck taper interface. Additional important mechanisms of interaction between the implant and the human body must be taken into account, i.e. diffusion stream of foreign particles and atoms from the implant to body fluids, to the tissue and to the bone. These foreign particles and atoms are released from the implant to the body fluid, to the tissue and to the bone as wear product during use. All together they contribute to the wear, i.e. loss of weight, strength or volume of hip components. Wear rates of ultrahigh molecular weight polyethylene mated against Ti-6Al-4V are significantly greater than the ones for Co-Cr-Mo alloys. Therefore, thermochemical surface treatments like diffusion ion nitriding should be applied to increase the resistance of titanium alloys to wear. Austenitic stainless steels are also used for temporary applications, but they have lower resistance to pitting corrosion than titanium and cobalt alloys. The purpose of the paper is to introduce a group of metallic materials, which is often chosen for surgical hip implants. Conclusions of the paper refer to information which support important medical and patient decisions on hip implants. Also, the development of biomaterials, their treatments, properties, surface layers and coatings are considered. All these features develop over time and need synergy and experience in the progress of the biomedical, mechanical and materials science.

Research of Residual Stress After Deformation and Annealing of a Titanium Alloy Ti-5Al-5Mo-5V-1Cr-1Fe Billets

Research of opening angle changes in bent billets of Ti-5Al-5Mo-5V-1Cr-1Fe alloy after bending and annealing at temperature 800°C for 1, 2, 3, 4, 5 hours has been madeto improve the accuracy of the titanium partsmanufacture. The change of surface residual micro- and macrostrains via X-ray analysis was found depending on the duration of annealingduration. It was found that the value of the opening angle between the legs bent billets is defined by the influence of the level of residual microstress. To maintain the geometry of the bent billets it is recommended to anneal them at a temperature of 800°C for 2 hours.

Present Situation and Prospect of Residual Stress Modelling Technology in Metal Cutting

Residual stress ,with the branch of type, size and direction, is defined as the stress state which exists in a body after all the external loads are removed [1].According to the mutual influence scope size,residual stress can be divided into macroscopic residual stress and micro residual stress. Cutting residual stress is mainly caused by mechanical stress, thermal stress and phase transformation.

Residual Stress in the Cementite Phase of Cold Drawn Pearlite*

AbstractResidual stressesin cold drawn, pearlitic steel wire have been measured using synchrotron diffraction. In this paper the cementite residual stress evolution is presented. A saturation of the residual stress could be observed. A simple analytical model is proposed to interpret the observed residual stresses in terms of the strain hardening behaviour of the phases present in the material. From the analytical model it follows that it is not reverse plastic yielding of the ferrite that is of primary importance in residual stress saturation, but the actual strain hardening behaviour. The experimentally observed saturation, followed by a gradual decrease of the residual micro phase stress, could be explained by an exponential strain hardening of the ferrite, while the cementite phase doesn't show significant strain hardening.

ENGLISH

Grinding is one of the most popularly used surface finishing process characterized by excellent process capabilities in terms of surface finish and material removal rate. It has wide applications in manufacturing industry as it can handle a wide variety of workpiece materials and forms. However it needs very high specific energy and gives rise to very high temperature, which results into high residual stresses, micro cracks and burn. To reduce these ill effects normally coolants are employed, which reduce the friction and provides effective cooling of work wheel interface. Conventional applications of coolants are many times ineffective due to inaccessibility of the fluid to grinding zone and film boiling. Many of the conventional coolants pose health hazard and support the green house effect. This paper deals with the use of solid lubricant, Molybdenum Disulphide carried in the proper medium to grinding zone and reducing the friction and hence eliminating the thermal ill effects on the grinding process. Results show that the grinding force, grinding energy and the surface roughness decreases with the help of the use of Molybdenum Disulphide compared with dry grinding and grinding with the conventional coolants.

Evolution of Residual Micro Phase and Orientation Dependent Stresses during Cold Wire Drawing

The residual grain and phase microstress evolutions in the ferrite matrix of pearlitic wires after several steps of cold wire drawing have been studied. Energy dispersive synchrotron diffraction revealed a significant divergence in the grain microstress evolution among differently oriented ferrite grains in the high deformation regime beyond accumulated true strain level εt ≥ 2.3.The possible physical reason for the observed divergence is discussed in terms of distinct microstructure development in this stage of the cold wire drawing.

Dose escalation using dose-painted IMRT in locally advanced rectal cancer.

582 Background: After preoperative chemo-radiation, clinical response and tumor pathologic downstaging showed a close correlation with improved outcomes. We report our initial experience in dose escalation using dose-painted intensity-modulated radiation therapy (DP-IMRT) in patients with locally advanced rectal cancer. Methods: Fifteen patients with locally advanced rectal cancer (T3-4,N0-1) were prospectively identified. Tumors were staged using the cTNM classification by PET/CT, EUS & MRI. All received preoperative 5-FU and DP-IMRT. Doses were prescribed as follows:56 Gy/2.0 Gy fractions (fxn) to the planning target volume (PTV) and 47.6Gy/1.7Gyfxn to elective nodal PTV. Surgery was performed 6-8 weeks after chemo-radiation. The surgical procedure was tailored to tumor downstaging. The choice of sphincter-preserving surgery was based on the distance between the lower tumor pole and the anorectal ring “ after” chemoradiation. All were reevaluated for tumor response, preoperatively by imaging studies (ycTNM) and by pathological staging (ypTN) following surgery. Acute and late toxicities were monitored by the treating physician. Results: All patients completed therapy. Tumors were in the lower 1/3 in 3 patients, middle 1/3 in 7, and upper 1/3 in 5. With preoperative endorectal US, PET/CT and MRI, the clinical staging of the tumors was: 13 (T3N0) and 2 (T4N0). Acute toxicity was limited to a moderate proctitis (RTOG acute toxicity scoring system, G1 ) in all patients, with two patients with tumors extending into the anal canal having G 3 dermatitis. Complete clinical response was obtained in 10 of 15 patients.All 15 underwent surgery; 6 had pathological pT0N0, 4 had residual micro foci of carcinoma (pT1N0), and 5 had residual disease limited to the muscularis propria (pT2N0). No difference in perioperative complications was seen. Conclusions: Preoperative dose-escalation using dose-painted radiation therapy (DP-IMRT) seems to be safe. Moderate local acute toxicity was seen with very low-lying tumors. This modality provides a high rate of tumor downsizing especially for patients with lesions in the lower 2/3 of the rectum with a possible potential for an increased ability to perform sphincter-preserving surgery.

A comparative analysis of basic characteristics of several deproteinized bovine bone substitutes

Purpose: Deproteinized bovine bone substitutes are commonly used in dental regenerative surgery for treatment of alveolar defects. In this study, three different bovine bone minerals - OCS-B (NIBEC, Seoul, Korea), Bio-Oss (Geistlich - Pharma, Switzerland), Osteograft/N - 300 (OGN, Dentsply Friadent Ceramed. TN, USA) - were investigated to analyze the basic characteristics of commercially available bone substitutes. Methods: Their physicochemical properties were evaluated by scanning electron microscopy, energy dispersive X-ray spectrometer (EDS), surface area analysis, and Kjeldahl protein analysis. Cell proliferation and alkaline phosphatase (ALP) activity of human osteosarcoma cells on different bovine bone minerals were evaluated. Results: Three kinds of bone substitutes displayed different surface properties. Ca/P ratio of OCS - B shown to be lower than other two bovine bone minerals in EDS analysis. Bio-Oss had wider surface area and lower amount of residual protein than OCS - B and OGN. In addition Bio - Oss was proved to have lower cell proliferation and ALP activity due to lots of residual micro particles, compared with OCS - B and OGN. Conclusions: Based on the results of this study, three bovine bone minerals that produced by similar methods appear to have different property and characteristics. It is suggested that detailed studies and quality management is needed in operations for dental use and its biological effects on new bone formation. (J Korean Acad Periodontol 2009;39:149-156)

Characterization of nanoindentation-induced residual stresses in human enamel by Raman microspectroscopy

The objective of this research was to investigate nanoindentation-induced residual stresses in human enamel using Raman microspectroscopy and establish if this approach can be used as a stress meter. Healthy human premolars and sintered hydroxyapatite samples were embedded, cut, and the surfaces were polished finely with a 0.05 microm polishing paste before Berkovich and spherical indentations were made with a force of 100 mN. Spectra were collected using a Renishaw Raman InVia reflex microscope equipped with an air-cooled charge-coupled device (CCD) camera. Sample excitation was achieved using either an argon ion laser emitting at 514.5-nm or a NIR diode laser emitting at 830-nm. The residual micro stresses within and surrounding the indentation impressions were monitored by mapping the position of the nu(1)(PO(4)) band of (crystalline) hydroxyapatite. The Raman maps coincided well with the optical micrographs of the samples. Despite the presence of a fluorescence background from the organic component of human enamel, spectra collected using 514.5-nm excitation exhibited more significant shifts in the position of the nu(1)(PO(4)) band than spectra collected using 830-nm excitation. This implies that the former excitation may be a more appropriate excitation for stress detection. It was concluded that Raman microspectroscopy provides a novel high-resolution and non-destructive method for exploring the role of microstructure on the residual stress distribution within natural biocomposites.

PL3W0400 Diffraction measurements of residual micro and macro stresses

The present paper reviews some recent developments of the measurements of micro- and macro-stresses by diffraction using X-rays, synchrotron and neutrons especially in Japan. These three methods are based on the same principle of the diffraction of crystals, and have different advantages. The conventional X-rays detect the stress very near the surface, while the neutron diffraction takes the stress in the interior of the materials. High-energy X-rays from synchrotron sources have the penetration depth in between and are suitable for the measurement of subsurface stresses. After describing the developments of the fundamentals of the methods, the paper covers the recent applications of the diffraction methods to the residual stress analysis in textured thin films, the nondestructive determination of the subsurface distribution of residual stress in shot-peened materials, local stress measurements near the crack tip, the stress measurements of single crystals, micro- and macro-stress measurements in composites, and the determination of the internal distribution of the residual stress in welding joints.

PL-3(PL3W0400) Diffraction Measurement of Residual Micro and Macro Stresses

PL-3(PL3W0400) Diffraction Measurement of Residual Micro and Macro Stresses

Micro-Mechanical Modeling of Polymer Based Unidirectional Composites: Use of Bulk Properties of Matrix with the Smeared Crack Model

Traditional approach to micro-mechanical modeling uses in situ properties of ingredients, which are so fitted as to match predictions of the micromechanical analysis with the experimental in-plane shear response of a lamina for a particular value of fiber volume fraction. In situ properties thus derived, cannot, in general, be used with a different fiber volume fraction or a different micromechanical model. The study presented here is based on the premise that micromechanical models should be transparent and rational tools for obtaining composite properties. Therefore, an attempt is made to characterize the composite from the actual properties of the ingredients and accounting for the presence of thermal residual stresses, shear softening and micro cracking in the matrix throughout the loading history. Experimental comparisons show that a micro-mechanical model with a realistic representative volume element (RVE) and diligent accounting of matrix behavior provides good bounds on experimental response with consistent accuracy, when bulk material properties are used.