Development and prospects of molten steel deoxidation in steelmaking process

In the long traditional process of steelmaking,excess oxygen is blown into the converter,and alloying elements are used for deoxidation.This inevitably results in excessive deoxidation of products remaining within the steel liquid,affecting the cleanliness of the steel.With the increasing requirements for steel performance,reducing the oxygen content in the steel liquid and ensuring its high cleanliness is necessary.After more than a hundred years of development,the total oxygen content in steel has been reduced from approximately 100×10^(-6)to approximately 10×10^(-6),and it can be controlled below 5×10^(-6)in some steel grades.A relatively stable and mature deoxidation technology has been formed,but further reducing the oxygen content in steel is no longer significant for improving steel quality.Our research team developed a deoxidation technology for bearing steel by optimizing the entire conventional process.The technology combines silicon–manganese predeoxidation,ladle furnace diffusion deoxidation,and vacuum final deoxidation.We successfully conducted industrial experiments and produced interstitial-free steel with natural decarbonization predeoxidation.Non-aluminum deoxidation was found to control the oxygen content in bearing steel to between 4×10^(-6) and 8×10^(-6),altering the type of inclusions,eliminating large particle Ds-type inclusions,improving the flowability of the steel liquid,and deriving a higher fatigue life.The natural decarbonization predeoxidation of interstitial-free steel reduced aluminum consumption and production costs and significantly improved the quality of cast billets.

New steelmaking process based on clean deoxidation technology

After the converter steelmaking process,a considerable number of ferroalloys are needed to remove dissolved oxygen from the molten steel,but it also forms a lot of oxide inclusions that cannot be completely removed.At the same time,it increases the carbon emis-sions in the steel production process.After years of research,our team have developed a series of clean deoxidation technologies,includ-ing carbon deoxidation,hydrogen deoxidation,and waste plastic deoxidation of molten steel to address the aforementioned issues.In this study,thermodynamic calculations and laboratory experiments were employed to verify that carbon and hydrogen can reduce the total oxygen content in the molten steel melt to below 5×10^(-6) and 10×10^(-6),respectively.An analysis of the deoxidation mechanisms and ef-fects of polyethylene and polypropylene was also conducted.In addition,the applications of carbon deoxidation technology in different steels with the hot-state experiment and industrial production were discussed carefully.The carbon deoxidation experimental results of different steels were as follows:(1)the oxygen content of bearing steel was effectively controlled at 6.3×10^(-6) and the inclusion number density was lowered by 74.73%compared to aluminum deoxidized bearing steel;(2)the oxygen content in gear steel was reduced to 7.7×10^(-6) and a 54.49%reduction of inclusion number density was achieved with almost no inclusions larger than 5μm from the average level of industry gear steels;(3)a total oxygen content of M2 high-speed steel was as low as 3.7×10^(-6).In industrial production practice,car-bon deoxidation technique was applied in the final deoxidation stage for non-aluminum deoxidized bearing steel,and it yielded excellent results that the oxygen content was reduced to below 8×10^(-6) and the oxide inclusions in the steel mainly consist of silicates,along with small amounts of spinel and calcium aluminate.

Investigation of the structural, electronic and mechanical properties of CaO–SiO_(2) compound particles in steel based on density functional theory

CaO–SiO_(2)compounds compromise one of the most common series of oxide particles in liquid steels, which could significantly affect the service performance of the steels as crack initiation sites. However, the structural, electronic, and mechanical properties of the compounds in CaO–SiO_(2)system are still not fully clarified due to the difficulties in the experiments. In this study, a thorough investigation of these properties of CaO–SiO_(2)compound particles in steels was conducted based on first-principles density functional theory. Corresponding phases were determined by thermodynamic calculation, including gamma dicalcium silicate(γ-C2S), alpha-prime(L) dicalcium silicate(αL′-C2S), alpha-prime(H) dicalcium silicate(αH′-C2S), alpha dicalcium silicate(α-C2S), rankinite(C3S2), hatrurite(C3S), wollastonite(CS), and pseudowollastonite(Ps-CS). The results showed that the calculated crystal structures of the eight phases agree well with the experimental results. All the eight phases are stable according to the calculated formation energies, and γ-C2S is the most stable. O atom contributes the most to the reactivity of these phases. The Young’s modulus of the eight phases is in the range of 100.63–132.04 GPa. Poisson’s ratio is in the range of0.249–0.281. This study provided further understanding concerning the CaO–SiO_(2)compound particles in steels and fulfilled the corresponding property database, paving the way for inclusion engineering and design in terms of fracture-resistant steels.

Effect of traveling-wave magnetic field on dendrite growth of high-strength steel slab: Industrial trials and numerical simulation

The dendrite growth behavior of high-strength steel during slab continuous casting with a traveling-wave magnetic field was studied in this paper. The morphology of the solidification structure and composition distribution were analyzed. Results showed that the columnar crystals could deflect and break when the traveling-wave magnetic field had low current intensity. With the increase in current intensity, the secondary dendrite arm spacing and solute permeability decreased, and the columnar crystal transformed into an equiaxed crystal. The electromagnetic force caused by the traveling-wave magnetic field changed the temperature gradient and velocity magnitude and promoted the breaking and fusing of dendrites. Dendrite compactness and composition uniformity were arranged in descending order as follows:columnar-toequiaxed transition (high current intensity), columnar crystal zone (low current intensity), columnar-to-equiaxed transition (low current intensity), and equiaxed crystal zone (high current intensity). Verified numerical simulation results combined with the boundary layer theory of solidification front and dendrite breaking–fusing model revealed the dendrite deflection mechanism and growth process. When thermal stress is not considered, and no narrow segment can be found in the dendrite, the velocity magnitude on the solidification front of liquid steel can reach up to 0.041 m/s before the dendrites break.

Orthogonal analysis of water model study on the optimization of flow control devices in a six-strand tundish

Improper flow control devices in a multi-strand tundish can cause some problems, for example, liquid steel cannot reach every nozzle at the same time and the liquid steel in nozzles far away from the entry zone has a lower temperature. The water model experiment of a six-strand tundish of Tianjin Iron ＆ Steel Co. Ltd. was performed, a new ＂U＂ type baffle was obtained, and its parameters were defined by perpendicular analysis. The ＂U＂ baffle can not only improve those imperfections, but also prolong the residence time of nonmetallic inclusions, which is good for their flotation and separation.

Psychological impact of the COVID-19 pandemic on healthcare workers:a cross-sectional study in China

Background Healthcare workers fighting against the coronavirus disease 2019(COVID-19)pandemic are under tremendous pressure,which puts them at an increased risk of developing psychological problems.Aims This study aimed to investigate the prevalence of psychological problems in different healthcare workers(ie,physicians,medical residents,nurses,technicians and public health professionals)during the COVID-19 pandemic in China and explore factors that are associated with the onset of psychological problems in this population during this public health crisis.Methods A cross-sectional,web-based survey was conducted in February 2020 among healthcare workers during the COVID-19 pandemic.Psychological problems were assessed using the Generalized Anxiety Disorder Scale,Patient Health Questionnaire and Insomnia Severity Index.Logistic regression analyses were used to explore the factors that were associated with psychological problems.Results The prevalence of symptoms of anxiety,depression,insomnia and the overall psychological problems in healthcare workers during the COVID-19 pandemic in China was 46.04%,44.37%,28.75%and 56.59%,respectively.The prevalence of the overall psychological problems in physicians,medical residents,nurses,technicians and public health professionals was 60.35%,50.82%,62.02%,57.54%and 62.40%,respectively.Compared with healthcare workers who did not participate in front-line work,front-line healthcare workers had a higher risk of anxiety,insomnia and overall psychological problems.In addition,attention to negative or neutral information about the pandemic,receiving negative feedback from families and friends who joined front-line work,and unwillingness to join front-line work if given a free choice were three major factors for these psychological problems.Conclusions Psychological problems are pervasive among healthcare workers during the COVID-19 pandemic.Receiving negative information and participating in front-line work appear to be.important risk factors for psychological problems.The psychological health of different healthcare workers should be protected during the COVID-19 pandemic with timely interventions and proper information feedback.

Distribution and segregation of dissolved elements in pipeline slab

The chemical composition in a cross section of a high grade pipeline slab was measured point by point （in a scale of 1 μm） using original position statistic distribution analysis （OPA）. The result indicated that negative segregation strips of Si, Mn, Mo, Ni, Cr, Nb, Cu, Ti, and V exist in the two sides 24 mm away from the central line, with a width of 8-12 mm, Negative segregation inside the central line is more severe than that outside the central line, and the highest positive segregation of the elements appears closely by the inner sides of the negative segregation strips. No obvious negative segregation strip of S and P is found. Segregation of the elements in the central area is higher than that in the outer and inner arc areas. The segregation of C, Ti, S, and P is high and that of Cr, Cu, Si, and Mn is low in the slab.

Decarburization mechanism of RH-MFB refining process

The overall decarburization mechanism can be divided into the decarburization in bulk molten steel and floating of CO against static pressure, the decarburization on the surface of argon bubbles and splashing particles. On the basis of each conception the RH-MFB decarburization mathematical model has been built according to the thermodynamic and mass conservation principle, and contributions of every decarburization mechanism were discussed and analyzed.

Development of a New Subermerged Entry Nozzle in Thin Slab Caster

The fluid flow in the mould of the thin slab continuous caster has a large intluence on the quality of slabs and its productivity.The fluid flow pattern can be controlled by the SEN (Submerged Entry Nozzle) structure. Traditional SEN can not decrease the surface turbulence and penetration depth at the same time, especially at high casting speed. In order to improve the fluid flow in the mould, a new structure SEN-Dissipation SEN have been invented. The water modeling experiments proved that the dissipation SEN could satisfy, the needs of fluid flow condition in the mould at high casting speed.

Experimental Study of Fluid Flow in Thin Slab Continuous Caster Mould with Water-Model

Model study is an efficient method for optimizing the siructure of the mould and the submerged entry nozzle (SEN). Based on the similarity criteria, a full-scale water model has been established in accordance with the mould of thin-slab caster of the CSP (Compact Strip Production) operation. The effects of SEN structure including outlet area, outflow angle, nozzle width, thick-ness and immersion depth have been studied under high speed casting by measuring the amplitude and the impetus of top waves. By the orthogonal experiment design, not only the influence of the faCtors was estimated, but also the optimum work condition was judged. The rules of the fluid flow phenomena were summarized. The principle for choosing a reasonable structure of SEN was discussed.

Dispersive bubble wall—a new method of flow control in tundish

Tundish is the last refractory vessel in the steelmaking process. The fluid flow phenomena in tundish have a strong influence on the separation of non-metallic inclusions. The dispersive bubble wall （DBW） is a new method in tundish metallurgy. A water model of a multi-strand tundish has been set up based on the Froude number and Reynold number similarity criteria. The effect of DBW＋weir on the flow pattern has been studied. The results show that this new structure of DBW＋weir is beneficial not only to uniform the temperature among different submerge entry nozzles but also to separate non-metallic inclusions from liquid steel. The DBW can capture the particles of non-metallic inclusions and make them float up to the surface.

Non-coding RNAs expression in SARS-CoV-2 infection:pathogenesis,clinical significance,and therapeutic targets

The coronavirus disease 2019(COVID-19)pandemic has been looming globally for three years,yet the diagnostic and treatment methods for COVID-19 are still undergoing extensive exploration,which holds paramount importance in mitigating future epidemics.Host non-coding RNAs(ncRNAs)display aberrations in the context of COVID-19.Specifically,microRNAs(miRNAs),long non-coding RNAs(lncRNAs),and circular RNAs(circRNAs)exhibit a close association with viral infection and disease progression.In this comprehensive review,an overview was presented of the expression profiles of host ncRNAs following SARS-CoV-2 invasion and of the potential functions in COVID-19 development,encompassing viral invasion,replication,immune response,and multiorgan deficits which include respiratory system,cardiac system,central nervous system,peripheral nervous system as well as long COVID.Furthermore,we provide an overview of several promising host ncRNA biomarkers for diverse clinical scenarios related to COVID-19,such as stratification biomarkers,prognostic biomarkers,and predictive biomarkers for treatment response.In addition,we also discuss the therapeutic potential of ncRNAs for COVID-19,presenting ncRNA-based strategies to facilitate the development of novel treatments.Through an in-depth analysis of the interplay between ncRNA and COVID-19 combined with our bioinformatic analysis,we hope to offer valuable insights into the stratification,prognosis,and treatment of COVID-19.

调节记忆关键时间窗口治疗精神疾病

随着社会及科技的高速发展,现代人类面临巨大的压力及突发公共卫生事件等不确定因素,各种精神疾病负担日益加重.物质成瘾及创伤后应激障碍等疾病与病理性记忆相关,它们往往因持久存在的创伤或者异常的奖赏记忆而难以治愈,尚缺乏有效的治疗及干预手段.既往研究发现抹除或者破坏创伤或者奖赏记忆是治疗此类精神障碍的关键.当已经稳定的记忆被再次唤起后,会进入一个不稳定的可干预的时间窗口,也就是“再巩固”过程,而干预记忆再巩固可作为治疗记忆相关精神疾病的重要靶点.本文综述了行为干预(如条件性和非条件线索唤起-消退心理学范式)、神经调控技术干预(如经颅磁刺激、经颅电刺激等)和药物干预等方式在特异时间窗内修改病理性记忆“再巩固”过程治疗相关精神疾病的研究进展,并对干预记忆再巩固策略的潜在优势、局限性、挑战和机遇进行了讨论.

Effective removal of phosphorus from high phosphorus steel slag using carbonized rice husk

High phosphorus steel slag and carbonized rice husk are two common wastes characterized by high generation and low secondary use values.Through the reduction of high phosphorus steel slag by biomass,both wastes were fully utilized,thus reducing the negative impact on the environment.In this study,variables such as temperature,time,and amount of reactants were changed to determine the optimal conditions for the reaction of steel slag with carbonized rice husk at high temperatures.The actual amount of reducing agent consumed during the reduction was significantly greater than that predicted by theoretical calculations.Adding three carbon equivalent of carbonized rice husk and maintaining at 1500℃ for 30 min could remove 79.25% of P_(2)O_(5) in the slag.By modeling the material cycle in which high phosphorus steel slag was treated with biomass,the product could be used for crop growth.Meanwhile,the reduced iron and residual steel slag can be used tomake steel again,thereby leading to a sharp reduction in fossil fuel usage and greenhouse gas emissions in this process.

跨越人工智能在精神疾病临床应用中的鸿沟

Mental disorder is one of the greatest health challenges of our time,attracting increasingly more public awareness and causing high disability and huge socioeconomic burdens.According to the 2019 Global Burden of Disease led by the Institute for Health Metrics and Evaluation,12.5%of the global population has been suffering from a mental disorder.Globally,mental illness contributes to 32.4%of years lived with disability and 13.0%of disability-adjusted life-years[1].

中国脑计划:从基础到临床

The complexity of the brain has attracted scientists from all over the world.Much effort has been paid to explore the mechanisms from genetics to molecules,from cells to circuits,and from Caenorhabditis elegans to humans.Brain research contributes to the development of new technologies,especially artificial intelligence(AI).According to the International Data Corporation,the global revenue of the AI market is expected to exceed$500 billion by 2023 and$900 billion by 2026,highlighting the great importance of brain research for social progress.

Causal relationships between chronotype and risk of multiple cancers by using longitudinal data and Mendelian randomization analysis

Dear Editor,Cancer is the second leading cause of death worldwide,and the cancer situation is becoming more complicated(Zhou et al.,2022).The International Agency for Research on Cancer(IARC)Monographs Working Group classified night shift work as probably carcinogenic(Group 2A)to humans in2019(Ward et al.,2019).

Prevalence and risk factors of cardiovascular diseases and psychological distress among female scientists and technicians

This study aimed to explore the prevalence and risk factors of cardiovascular disease(CVD)and psychological distress among female scientists and technicians in China.Accordingly,we included scientists and technicians from representative research institutions,medical institutions,colleges,universities,and businesses in China,and the data were collected from July 1,2019 to March 31,2021 via online questionnaires.The parameters evaluated in this study included age,sex,marital status,educational background,monthly income,sleep hours,sleep problems,smoking,alcohol consumption,work-related stress,work burnout,cardiovascular symptoms,CVD,family history,and depressive and anxiety symptoms.A total of 14530 scientists and technicians were included,comprising 7144 men and 7386 women.We found 34.9%men and 16.6%women with CVD,35.1%men and 21.4%women with depressive symptoms,28.7%men and 13.8%women with anxiety symptoms,and 22.0%men and9.5%women with CVD combined with depressive or anxiety symptoms.This study focused on the details of women.Younger women(age≤35 years)had the highest prevalence of depressive symptoms(24.9%),anxiety symptoms(16.2%),and comorbidity(11.2%).It was established that,despite traditional risk factors,unmanageable work burnout,depressive symptoms,and anxiety symptoms were associated with a higher risk of CVD in women;insomnia,overwhelming work stress,unmanageable work burnout,and CVD were linked to a higher risk of depressive symptoms and anxiety;insomnia,overwhelming work stress,and unmanageable work burnout were related to CVD combined with depressive or anxiety symptoms.A bidirectional relationship was noted between CVD and depression or anxiety in female scientists and technicians,and insomnia and overwhelming work stress were positively associated with comorbidity.It is suggested that effective measures should be taken to protect female scientists and technicians from CVD and psychological distress.

COVID-19大流行中的精神心理问题与应对策略

The coronavirus disease-2019(COVID-19)pandemic has imposed a huge burden on global public health.Even before the pandemic,mental health disorders were among the leading reasons for the global health-related burden,and COVID-19 intensified this global crisis for mental health.Stressors such as fear of infection,persistent social distancing measures.

Online Survey on Accessing Psychological Knowledge and Interventions During the COVID-19 Pandemic-China, 2020

Summary What is already known on this topic?The public was at elevated risk of mental health illnesses during the coronavirus disease 2019(COVID-19)pandemic,so accessibility to psychological knowledge and interventions is vital to promptly respond to mental health crises.What is added by this report?During the pandemic period,40,724(71.9%)participants reportedly had access to psychological knowledge,and 36,546(64.5%)participants had accessed information on psychological interventions.Participants who were male,unmarried,living alone,divorced or widowed,or infected with COVID-19 were less likely to access psychological knowledge and intervention.