Influence of rigid body motion on the attachment of metallic droplets to solid particles in liquid slags - a phase field study

Metallic droplets can remain attached to solid particles within liquid slags, resulting in production losses in several pyrometallurgical industries. This study shows the extension of a recently developed phase field model to include the movement of solid particles in the liquid slag in a system, considering the attachment of liquid metal droplets to solid particles in slags. The influence of this movement on the wetting of the metal droplets to the solid particles in the slag and on the resulting microstructures is investigated as a function of the velocity of the particles. For all wetting regimes, the apparent contact angle in the final microstructures was clearly larger than without particle movement. For the amount of metal attached to the particle, a clear trade-off was found between the speed of motion of the solid particle and the wetting regime

Grain Growth in Thin Films with a Fibre Texture Studied by Phase-Field Simulations and Mean Field Modelling

The evolution of fiber textured structures is simulated in 2 dimensions using a generalized phase field model assuming two forms for the misorientation, a steady-state regime is reached after a finite amount of grain growth, where the numer and length weighted misorientation distribution functions (MDF) are constant in time, and the mean grain area A as a function of time t follows a power growth law A - A0 = kt^n with n close to 1 and A0 the initial mean grain area. The final shape of the MDF and value of the prefactor k in the power growth law clearly correlate with the misorientation dependence of the grain boundary energy. From a quantitative point of view, the fraction of special boundaries obtained in simulations is quite sensitive to the number of possible discrete orientations. Furthermore, a mean field approach is worked out to predict the growth exponent for systems with nonuniform grain boundary energy. The conclusions from the mean field approach are consistent with the simulation results.Physic

Phase-field modelling in extractive metallurgy

The phase-field method has already proven its usefulness to simulate microstructural evolution for several applications, e.g. during solidification, solid-state phase transformations, fracture, etc. This wide variety of applications follows from its diffuse-interface approach. Moreover, it is straightforward to take different driving forces into account. The purpose of this paper is to give an introduction to the phase-field modelling technique with particular attention for models describing phenomena important in extractive metallurgy. The concept of diffuse interfaces, the phase-field variables, the thermodynamic driving force for microstructure evolution and the phase-field equations are discussed. Some of the possibilities to solve the equations describing microstructural evolution are also described, followed by possibilities to make the phase-field models quantitative and the phase-field modelling of the microstructural phenomena important in extractive metallurgy, i.e. multi-phase field models. Finally, this paper illustrates how the phase-field method can be applied to simulate several processes taking place in extractive metallurgy and how the models can contribute to the further development or improvement of these processes.status: publishe

Metal droplet entrainment by solid particles in slags : an experimental approach

This study investigates the origin of the attachment of metal droplets to solid spinel particles in liquid slags. Previous research hinted a reactive origin: the spinel particles form by a chemical reaction together with a new droplet or alongside a droplet that was already present in the system. In this study, a smelting experiment was used to investigate this hypothesis. For such a study of the mechanism, a simple chemical system was used to avoid complex reactions. However, performing smelting experiments in simple slag systems requires an adaptation of the previously developed experimental methodology, resulting in a new 'partial melting' methodology. During the experiment, the atmosphere of the system was first set as oxidative, to dissolve the metallic copper in the slag and then a reductive atmosphere was used to actuate the reaction. Moreover, Ag was added to the metallic phase to act as a tracer element. The results show that the amount and size of copper droplets increase over the duration of the experiment. The fact that silver is present in the attached copper droplets in a smaller concentration than in the master alloy in this study indicates that the origin of the attachment is not purely dispersive, and either a purely reactive or a dispersion-reaction combination is possible, which confirms the hypothesis

Metal losses in pyrometallurgical operations - a review

Nowadays, a higher demand on a lot of metals exists, but the quantity and purity of the ores decreases. The amount of scrap, on the other hand, increases and thus, recycling becomes more important. Besides recycling, it is also necessary to improve and optimize existing processes in extractive and recycling metallurgy. One of the main difficulties of the overall-plant recovery are metal losses in slags, in both primary and secondary metal production. In general, an increased understanding of the fundamental mechanisms governing these losses could help further improve production efficiencies. This review aims to summarize and evaluate the current scientific knowledge concerning metal losses and pinpoints the knowledge gaps. First, the industrial importance and impact of metal losses in slags will be illustrated by several examples from both ferrous and non-ferrous industries. Throughout the remainder of this review, the main focus will be put on the particular issues in copper industry. In a second section, the different types of metal losses in slags will be discussed. Generally, metal losses in slags can be subdivided into two types: chemical losses and physical losses. The fundamental insights concerning the responsible mechanisms will be discussed for each type. Subsequently, an overview of the most frequently used techniques for research investigations of the losses will be given. In a fourth section, a more detailed overview will be given on the post-processing treatment of metal-containing slags, i.e. performing slag cleaning operations. The most frequently applied methods will be discussed.status: publishe

Topoisomerase 2A gene amplification in breast cancer. Critical evaluation of different FISH probes

The HER2 amplicon on chromosome 17q is variable in size and occasionally includes Topoisomerase 2A (TOP2A) at 17q21-22. It has been suggested that TOP2 co-amplification, not HER2 amplification on chromosome 17q11.2-12, is a useful predictive marker of response to anthracycline-based chemotherapy in breast cancer patients. Given the significant toxicities of anthracyclines, the detection methods of TOP2A gene amplifications have to be standardized. We determined TOP2A gene alterations using two different fluorescence in situ hybridization (FISH) DNA probes. HER2 amplifications were identified with the PathVysion™ probe. TOP2A status of 42 HER2 amplified breast cancers was tested by FISH with PathVysion™ covering 160kb and DAKO pharm DX™ covering 228kb of the TOP2A amplicon. TOP2A protein expression was tested by immunohistochemistry. Multiplex-ligation dependent probe amplification (MLPA) was performed retrospectively in cases showing discrepancies. TOP2A was amplified in 15 of 42 cases (35%) with DAKO pharm DX™ and in 11 of 42 cases (26%) with PathVysion™. In all four discrepant cases, MLPA showed no TOP2A amplification, but instead amplification of an upstream region including HER2. TOP2A was deleted in the same seven of 42 carcinomas (17%) with both probes. TOP2A protein expression was detected in all 42 tumours (100%) with high intratumoral heterogeneity. TOP2A amplification rate depends on the length of the hybridized probes for the TOP2A locus. Because TOP2A, not HER2, is a target of anthracyclines, non-overlapping DNA probes should be used to evaluate any associations between such alterations and response to anthracycline-based chemotherap

Малий бізнес в Україні: окремі аспекти сучасного стану та проблеми подальшого розвитку

У статті розглянуто деякі аспекти сучасного стану підприємництва в Україні у порівнянні з розвинутими країнами світу; визначені актуальні проблеми подальшого розвитку малого бізнесу, його роль і потенційні можливості у подоланні кризових явищ в економіці держави; окреслена необхідність істотного покращення державної регуляторної політики у сфері підприємництва, нагальні потреби підвищення якості управління бізнесовими структурами.In the article main aspects of current state of entrepreneurship in Ukraine are reviewed in comparison with developed countries, problems of small and medium business further development and it’s role and potential ability in overcoming crisis event in country economy are determined, necessity of substantial improvement of government regulation politic and also emergency need of business structures management quality improvement are presented

Low frequency of HER2 amplification and overexpression in early onset gastric cancer

BACKGROUND: The recent ToGA trial results indicated that trastuzumab is a new, effective, and well-tolerated treatment for HER2-positive gastric cancer (GC). Although GC mainly affects older patients, fewer than 10% of GC patients are considered early-onset (EOGC) (presenting at the age of 45 years or younger). These EOGC show different clinicopathological and molecular profiles compared to late onset GC suggesting that they represent a separate entity within gastric carcinogenesis. In light of potential trastuzumab benefit, subpopulations of GC such as EOGC (versus late onset) should be evaluated for their frequency of amplification and overexpression using currently available techniques. METHODS: Tissue microarray (TMA) blocks of 108 early onset GC and 91 late onset GC were stained by immunohistochemistry (IHC, Hercep test, DAKO) and chromogenic in situ hybridization (CISH, SPoT-Light, Invitrogen). RESULTS: Overall, we found only 5% HER2 high level amplification and 3% HER2 3+ overexpression (6/199). In addition, 8 patients (4%) showed a low level CISH amplification and 9 patients (4.5%) showed a 2+ IHC score. IHC and CISH showed 92% concordance and CISH showed less heterogeneity than IHC. In 2/199 cases (1%), IHC showed clinically relevant heterogeneity between TMA cores, but all cases with focal IHC 3+ expression were uniformly CISH high level amplified. Early onset GCs showed a significantly lower frequency of HER2 amplification (2%) and overexpression (0%) than late onset GCs (8% and 7% respectively) (p = 0.085 and p = 0.008 respectively). Proximal GC had more HER2 amplification (9% versus 3%) and overexpression (7% versus 2%) than distal tumours although this difference was not significant (p = 0.181 and p = 0.182 respectively). HER2 CISH showed more high level amplification in the intestinal type (7%, 16% if low-level included) compared to the mixed (5%, 5% if low-level included) and diffuse type (3%, 4% if low-level included) GCs (p = 0.029). A similar association was seen for HER2 IHC and histologic type (p = 0.008). Logistic regression indicated a significant association between HER2 expression and age, which remained significant when adjusted for both location and histological type. CONCLUSIONS: Even focal HER2 overexpression in GC points to uniform HER2 amplification by CISH. We show for the first time that early onset GC has a lower frequency of HER2 amplification and overexpression than late onset GC, and confirm that intestinal type GC shows the highest rate of HER2 amplification and overexpression