Suppressing initial clog deposits on inner surface of submerged entry nozzle refractory for casting liquid steel: Absorbing CO gas by CO absorbers

A series of experiments and thermodynamic analyses were carried out to find a countermeasure to prevent submerged entry nozzle clogging during continuous casting of Ti-added Ultra-Low C (Ti-ULC) steel, by suppressing CO gas generation in the nozzle refractory. SiO2 and C in usual nozzle refractories proceeded a carbothermic reaction, which generated the CO gas. The CO gas then reoxidized Ti-ULC steel, and a mixture of alumina and FetO-Al2O3-TiOx liquid oxide formed, which was reported to be an initial clog deposit. A concept of "CO absorber" was proposed to absorb the generated CO gas back into the refractory, thereby suppressing the reoxidation. This decreased the thickness of the reoxidation reaction product layer at the interface between the refractory and the steel, which could play as the initial clog deposit. Al4C3, B4C, CaC2, and Al were considered as the candidates for CO absorbers. It was found that B4C was the best candidate thanks to its anti-hydration character, high-temperature stability, and the extent of absorbing CO gas. A series of hot tests were carried out by reacting synthesized refractories in which a certain amount of the candidates were blended. The refractory with 3 mass pct. B4C showed the best result.11Nsciescopu

Becoming a doctor: using social constructivism and situated learning to understand the clinical clerkship experiences of undergraduate medical students

Abstract Background Despite the emphasis on the uniqueness and educational importance of clinical clerkships in medical education, there is a lack of deep understanding of their educational process and outcomes. Especially due to an inherent trait of clinical clerkships which requires participation in the workplace outside the classroom, it is difficult to fully comprehend their educational potential using traditional learning perspectives such as imbibing outside knowledge. Accordingly, this study aims to explore the experiences of a rotation-based clerkship of medical school students from the perspective of social constructivism of learning, which can empirically examine what and how medical students learn during clinical clerkship in South Korea. By providing an insight into the workings of the clerkship process, this study contributes to a better understanding of how a learning-friendly environment can be cultivated at clinical clerkships. Methods The study utilized a basic qualitative study to understand what and how medical students learn during their clinical clerkships. Semi-structured, in-depth individual interviews were conducted with eight sixth-graders who had experienced a two-year clerkship at Ajou University Medical School. Data were analyzed based on Lave and Wenger’s situated learning theory and Wenger’s social theory in learning. Results We found that the medical students had developed different aspects of their professional identities such as values, functionality, career decisions, sociality, and situating during their clinical clerkships. Further, professional identity was formed through a combination of participation and reification—the processes involved in the negotiation of meaning. This combination was facilitated by the students’ first experience and relationships with professors, classmates, and patients. Finally, non-learning occurred in the context of over-participation (learning anxiety and alienation) or over-reification (evaluation and e-portfolio). Conclusions This study revealed five sub-professional identities and their formation process from the learners’ perspective, thereby uncovering the unique learning characteristics and advantages of rotated-based clerkship and contributing to a further understanding of how gradual improvements can be made to the traditional clerkship education of medical students

Effect of Trace of Oxygen in Ar Gas on Initial Growth of Nozzle Clogging Deposits on SEN for Ti Added Ultra‐Low C Steel Casting

The possibility of reoxidation of Ti-ultra-low C (Ti-ULC) steel by a trace of oxygen in Ar gas, which is injected in a submerged entry nozzle (SEN), is investigated. A commercial-grade unpurified Ar gas with PO2 = ≈10−4 bar and a purified Ar gas with PO2 = ≈10−18 bar by a set of cleaning kits are employed. Preliminary thermodynamic calculations revealed that the unpurified Ar gas could cause significant oxidation of the Ti-ULC steel, irrespective of the steel composition, while the purified Ar gas did not oxidize the steel. A series of laboratory-scale oxidation experiments are carried out using various Ti-ULC steel samples and the two Ar gases. The oxidation under unpurified Ar gas causes the oxidation of all the samples but only on the surface, in partial agreement with the thermodynamic calculation. The partial agreement between the calculation and the experiment is explained by the availability of oxygen and other metallic elements. It is found that the trace of oxygen in a commercial grade of Ar gas could cause reoxidation of Ti-ULC steel in an SEN, which may be no better than the reoxidation by CO gas generated by the carbothermic reaction in the SEN refractory. A purity control of Ar gas is recommended. © 2022 Wiley-VCH GmbH.11Nsciescopu

Simple Shading Correction Method for Brightfield Whole Slide Imaging

Whole slide imaging (WSI) refers to the process of creating a high-resolution digital image of a whole slide. Since digital images are typically produced by stitching image sequences acquired from different fields of view, the visual quality of the images can be degraded owing to shading distortion, which produces black plaid patterns on the images. A shading correction method for brightfield WSI is presented, which is simple but robust not only against typical image artifacts caused by specks of dust and bubbles, but also against fixed-pattern noise, or spatial variations in pixel values under uniform illumination. The proposed method comprises primarily of two steps. The first step constructs candidates of a shading distortion model from a stack of input image sequences. The second step selects the optimal model from the candidates. The proposed method was compared experimentally with two previous state-of-the-art methods, regularized energy minimization (CIDRE) and background and shading correction (BaSiC) and showed better correction scores, as smooth operations and constraints were not imposed when estimating the shading distortion. The correction scores, averaged over 40 image collections, were as follows: proposed method, 0.39 ± 0.099; CIDRE method, 0.67 ± 0.047; BaSiC method, 0.55 ± 0.038. Based on the quantitative evaluations, we can confirm that the proposed method can correct not only shading distortion, but also fixed-pattern noise, compared with the two previous state-of-the-art methods

Influence of Al/Ti Ratio in Ti-ULC Steel and Refractory Components of Submerged Entry Nozzle on Formation of Clogging Deposits

Nozzle clogging during continuous casting of Ti-ULC (Ultra Low C) steel was investigated by inspections of plant -used SENs and laboratory scale experiments using a rotating finger method. Various Alin ratios in the steel and different kinds of nozzles (with or without CaO) were employed. Clog deposits found in the used SENs were composed of complicated oxide (CaO-Al(2)O(3-)TiOx,-...), Fe drops and chunks. Increasing Ti concentration increased amount of the deposit the metallic deposits. In the laboratory scale experiments, increasing Al/Ti ratios was effective to suppress the formation of the deposit and the oxidation loss of Ti in the steel. When a refractory without CaO was used, increasing Al/Ti ratio decreased the portion of Ti oxide in the deposit. Almost no Fe drops were observed, except for a thin layer of Fe on surface of the oxide deposit. When CaO-lined refractory was used, many numbers of Fe drops were found inside the deposit. Increasing Al/Ti ratio lowered Ti peak in the oxide deposit. The present results lend a strong support that Ti-ULC steel is oxidized by CO gas from nozzle refractory, forming FetO-containing liquid oxide and solid alumina. The liquid oxide is reduced to leave Fe drops and AL(2)O(3) TiO, layer. If CaO presents in the nozzle, then a complicated oxide of CaO Al2O3 TiO, forms, as was found in the SEN from the practical operation.11Ysciescopu

Development of Intraoperative Near-Infrared Fluorescence Imaging System Using a Dual-CMOS Single Camera

We developed a single-camera-based near-infrared (NIR) fluorescence imaging device using indocyanine green (ICG) NIR fluorescence contrast agents for image-induced surgery. In general, a fluorescent imaging system that simultaneously provides color and NIR images uses two cameras, which is disadvantageous because it increases the imaging head of the system. Recently, a single-camera-based NIR optical imaging device with quantum efficiency partially extended to the NIR region was developed to overcome this drawback. The system used RGB_NIR filters for camera sensors to provide color and NIR images simultaneously; however, the sensitivity and resolution of the infrared images are reduced by 1/4, and the exposure time and gain cannot be set individually when acquiring color and NIR images. Thus, to overcome these shortcomings, this study developed a compact fluorescent imaging system that uses a single camera with two complementary metal–oxide semiconductor (CMOS) image sensors. Sensitivity and signal-to-background ratio were measured according to the concentrations of ICG solution, exposure time, and camera gain to evaluate the performance of the imaging system. Consequently, the clinical applicability of the system was confirmed through the toxicity analysis of the light source and in vivo testing

Squid-inspired and wirelessly controllable display for active camouflage in aquatic-environment

Abstract Achieving optimal camouflage in an aquatic environment necessitates the ability to modulate transmittance in response to the surrounding obscurity and potential threats. This adaptation involves a dynamic transition from transparency to a deep-blue color, especially in low-light or dark situations. Such a strategy promotes a seamless assimilation with the surroundings, enabling the absorption of searchlights and, subsequently, diminishing the risk of detection by predators. Therefore, the presence of sophisticated mechanisms that facilitates stable and efficient control of transmittance is imperative, enabling smooth transition between transparent and deep-blue hues within the aquatic environment. This study presents nature-inspired programmable camouflage system that integrates an electrochromic display as the primary transmittance change element and a wireless base module for power and data transmission. Such technology offers a robust and flexible construction, ensuring stable operation as demonstrated through mechanical-fatigue experiments and quantitative simulation. A custom circuit and a power-control software package enable active control of multiple electrochromic displays while submerged in water