The Independent Probabilistic Firing of Transcription Factors: A Paradigm for Clonal Variability in the Zebrafish Retina.

Early retinal progenitor cells (RPCs) in vertebrates produce lineages that vary greatly both in terms of cell number and fate composition, yet how this variability is achieved remains unknown. One possibility is that these RPCs are individually distinct and that each gives rise to a unique lineage. Another is that stochastic mechanisms play upon the determinative machinery of equipotent early RPCs to drive clonal variability. Here we show that a simple model, based on the independent firing of key fate-influencing transcription factors, can quantitatively account for the intrinsic clonal variance in the zebrafish retina and predict the distributions of neuronal cell types in clones where one or more of these fates are made unavailable.BDS and SR acknowledge the support of the Wellcome Trust (098357/Z/12/Z). WAH and HB also acknowledge the support of the Wellcome Trust (100329/Z/12/Z). HB was also supported by the Swedish Research Council (2011-7054).This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.devcel.2015.08.01

Verification of Possibility of Molten Steels Decopperization with ZnAl₂O₄

In the previous research works, ZnAl2O4 material was considered as one of the solutions for the decopperization process of molten steels; up to 33% of decopperization efficiency was reported by utilising the ZnAl2O4 filter. In order to verify the decopperization possibility of ZnAl2O4 materials, iron-based alloys with various copper and carbon contents were interacted with ZnAl2O4 substrates in a heating microscope under an argon gas atmosphere at 1600 °C. Fe-Cu alloys were found to react with the ZnAl2O4 substrate during the interaction process, and a reaction layer with a complex composition around the alloy droplet was formed; however, Cu was not detected in the reaction layer. Cu was later found infiltrated inside of the ZnAl2O4 substrates. Furthermore, the Cu-Zn compounds were detected when the copper content in Fe-Cu alloys was 10 wt% Cu. After interaction experiments, copper was decreased in all cases. Thereby, the copper evaporation and infiltration into the ZnAl2O4 substrate were considered as the reasons for copper loss. Moreover, oxygen dissolved in melt was found to have a great effect on the copper evaporation process

Verification of Possibility of Molten Steels Decopperization with ZnAl2O4

In the previous research works, ZnAl2O4 material was considered as one of the solutions for the decopperization process of molten steels; up to 33% of decopperization efficiency was reported by utilising the ZnAl2O4 filter. In order to verify the decopperization possibility of ZnAl2O4 materials, iron-based alloys with various copper and carbon contents were interacted with ZnAl2O4 substrates in a heating microscope under an argon gas atmosphere at 1600 °C. Fe-Cu alloys were found to react with the ZnAl2O4 substrate during the interaction process, and a reaction layer with a complex composition around the alloy droplet was formed; however, Cu was not detected in the reaction layer. Cu was later found infiltrated inside of the ZnAl2O4 substrates. Furthermore, the Cu-Zn compounds were detected when the copper content in Fe-Cu alloys was 10 wt% Cu. After interaction experiments, copper was decreased in all cases. Thereby, the copper evaporation and infiltration into the ZnAl2O4 substrate were considered as the reasons for copper loss. Moreover, oxygen dissolved in melt was found to have a great effect on the copper evaporation process

Automated feature analysis as a tool for non-metallic inclusion analysis in solidified metals

In-depth analysis of the non-metallic inclusion population in solidified metals is essential considering the high cleanliness requirements for metallic components. For this purpose, automated feature analysis (AFA) is a powerful inclusion analysis tool, providing statistical supported information about quantity, elemental composition, morphology and size of inclusions. However, thorough data evaluation is imperative to ensure accurate and reliable results. The paper introduces the key principles of evaluating AFA data, emphasizing its capabilities and constraints by utilizing four large datasets obtained from solidified steel blocks, each containing a minimum of 4000 features. Additionally, methodologies for identifying characteristic inclusion species within a dataset, constructing suitable rulefiles for inclusion classification through statistical analyzes, and interpreting the resulting outcomes are presented. The size distribution of inclusions is analyzed using population density functions, focusing on the absolute inclusion count within specific size ranges. Cluster analysis is presented considering the inclusions‘ positional parameters

Studies on the use of two different magnesia-carbon recyclates as secondary raw material for MgO–C refractories

Two magnesia-carbon (MgO–C) recyclates were investigated with respect to their utilization as raw materials for MgO–C refractories. X-ray diffraction and backscattered electron diffraction were used for phase analysis of the recyclate aggregates. In addition, the gas released from one of the recyclates when it came into contact with water was analyzed in a mass spectrometer. MgO–C samples with different recyclate contents were produced. During coking, the samples showed different behavior depending on the recyclate used. Whereas those containing the first recyclate showed a slight shrinkage, a significant increase in volume was observed in the case of the specimens that contained the second recyclate. The volume increase could be reduced by thermal pretreatment of this recyclate at 380 °C. As a result, better bulk density and porosity values were obtained. However, an even stronger positive effect was achieved by replacing the pitch-based binder used in the binder system with a novolak-based

In situ layer formation on MgO–C refractories with different MgO grade by static and dynamic contact with liquid steel

Modern, high-quality steelmaking requires a comprehensive understanding of the behavior of refractories in service. Therefore, MgO–C refractories with different MgO grade were immersed once and twice into a steel melt at 1600 °C and 1680 °C, respectively, in a near-industrial steel casting simulator. The same materials were tested in static crucible melting tests. A coherent MgO layer containing low-melting phases and MgAl2O4 crystal-like structures formed on the specimens’ surface. The morphology and frequency of these structures were strongly related to the MgO grade of the specimens and the immersion procedure. A lower MgO grade caused an increased formation of low-melting phases, which contributed to a denser layer formed on the specimens’ surface, hampering gas diffusion and the formation of MgAl2O4 crystal-like structures. An increased steel melt temperature and the double immersion had a similar effect. Conversely, an excessive formation of MgO and/or MgAl2O4 was observed when the formed layer contained less low-melting phases

Recyclate-containing magnesia-carbon refractories – Influence on the non-metallic inclusions in steel

The fabrication of MgO–C refractories containing MgO–C recyclates is a current approach for saving resources and energy. However, it must be ensured that the steel quality is not adversely affected, particularly with regard to non-metallic inclusions. The present study investigates MgO–C refractories containing different proportions of MgO–C recyclates (up to 83%) in contact with 16MnCr5 steel melt and a slag. A recyclate-free MgO–C material served as a reference. The tests were performed in a steel-casting simulator. By an automated feature analysis of the solidified steel, manganese sulfide and complex alumina-manganese sulfide inclusions were found to be the predominant ones in all steel samples. No negative influence of the recyclate on the inclusion count and the size distribution of the inclusions, the latter being determined for the sum of alumina and alumina-manganese sulfide as well as for the manganese sulfide inclusions, was observed