Industrial Trials Research Articles

Influence mechanism of rare earth (RE) on inclusion modification in non-oriented silicon steel

Effects of rare earth (La+Ce) on inclusions in hot-rolled band of 3.0∼3.3%Si-0.8∼1.0%Al non-oriented silicon steel was studied using industrial trials, scanning electron microscope (SEM) and thermodynamic analysis. Furthermore, combining Heterogeneous Nucleation Theory with Edge-to-Edge Matching (E2EM) model, the formation mechanism of complex inclusions was also investigated. Rare earth (La+Ce) would promote the spheroidization and coarsening of inclusions, and then transform into regular and near circle morphology composite inclusions of rare earth. The low content of rare earth (21 ppm) mainly deoxidized and modified Al2O3 inclusions, and formed (La,Ce)AlO3 inclusions. Increasing of rare earth (29–45 ppm) would promote the formation of (La,Ce)AlO3-(La,Ce)2O2S and (La,Ce)2O2S inclusions, reduce the sulfide precipitation, and promote a gradual transformation of the core of composite inclusions from (La,Ce)AlO3 to (La,Ce)AlO3-(La,Ce)2O2S and (La,Ce)2O2S, which agreed well with the thermodynamic analysis. However, rare earth (29–45 ppm) had a weak metamorphic effect on Al2O3 inclusions generated by temperature drop and secondary oxidation. LaAlO3, CeAlO3, La2O2S and Ce2O2S could be the heterogeneous nucleation core of AlN, Al2O3, MgO-Al2O3, typical composite inclusions with (La,Ce)AlO3 and (La,Ce)2O2S as the core would ultimately form.

Fabrication and performance evaluation of CICC jacket based on modified N50 austenitic steel for CFETR magnet

The hot deformation behavior of modified N50 austenitic stainless steel in the temperature range 950∼1250 °C and strain rate range of 0.01–50/s was studied by uniaxial compression experiment. The processing map and the constitutive equation for the finite element simulation were established, and the recrystallization mechanism was discussed. The results indicated that the dominant deformation mode DDRX (discontinuous dynamic recrystallization) increased with the rise of deformation temperature while the CDRX (continuous dynamic recrystallization) was on the contrary. There is a decrease in global recrystallization with increasing strain rate, up to a threshold 1/s beyond which the global recrystallization began significantly promotion owing to not only the adiabatic heat and higher stored energy, but also quick Post-DRX mechanism induced by delay quenching. The reasonable hot working interval was determined by a hot working map, then the most suitable hot extrusion parameters (1180°C-100 mm/s) were further obtained with the help of finite element simulation, and ultimately, the industrial hot extrusion trials of N50 pipes with Post-DRX features were further completed. The tensile performance of final jacket pipes was far beyond the current mainstream low-temperature austenitic structural steel and met the requirements of the new generation of superconducting coil jacket materials.

Effect of Al-Ti complex deoxidation mode on steel cleanliness during RH refining of IF steels

The deoxidation in Ti containing Al killed IF steels is a vital parameter that directly influences the steel cleanliness. In this study, the evolution of steel compositions and inclusion characteristics during RH refining of IF steels were investigated by industrial trials involving three Al-Ti deoxidation modes, which were adding Ti-Fe 2 min after Al deoxidation in Mode I, adding Al and Ti-Fe simultaneously in Mode II, and adding Ti alloys with two equal batches at 3.2 min and 5 min after Al deoxidation in Mode III. The results showed that nitrogen pickup of several ppm was observed with Ti-Fe alloy addition. Therefore, nitrogen content in alloys should be strictly controlled. The main inclusions were single alumina particles, alumina clusters, alumina cluster with Al-Ti oxides, and Al-Ti complex oxides. Mode III had less amount of Al-Ti oxides compared with Mode I, and Mode II had a much higher proportion of Ti bearing inclusions than Mode I and Mode III at RH end. For Mode I & Mode III, the inclusion removal rate was 0.33–0.35 min−1 before adding Ti, and slowed down to 0.14 min−1 for Mode I and 0.22 min−1 for Mode III after Ti-Fe addition. While for Mode II, the rate was only 0.18 min−1. Mode III was the recommended mode for its excellent steel cleanliness and high Ti yield with slight elongation of RH treating time.

A method for measuring the solid circulation rates of CFB boilers based on the particle flow-around principle

The solid circulation rate (Gs) is a key parameter for the design and operation of a circulating fluidized bed (CFB) industrial equipment, while the detection and measurement of the Gs value in an actual industrial CFB equipment remains difficult. To fill this gap, a method for the Gs measurement based on the flow-around principle was proposed in this study. The mathematical model for the signal transformation was established along the path “detected strain value – impact force – particle velocity – Gs value”, and the corresponding measurement device was also developed. The performance of the Gs measurement device was quantitatively validated in cold-state experiments and semi-quantitatively verified in an industrial trial in a CFB boiler. The results of a theoretical analysis indicate that the detected strain linearly increased with the impact force received by the intrusive spherical obstacle, and the slope coefficient was determined as per the experiment. The correlation of the impact force to the particle flow velocity was proposed and fitted using the experimental data. The computational particle fluid dynamics method was applied to simulate the particle flow field in the standpipe of the CFB boiler to determine the installation location of the Gs measurement device. The lab-scale cold-state experiments showed that the relative standard uncertainty of the Gs measurement using the device built in the present study was less than 2.0 %. This device was then applied in an industrial trial in a 116 MWth CFB boiler and the results proved the feasibility and applicability of the proposed Gs measurement method.

Development and performance of the c4c national clinical trial networks for optimizing pediatric trial facilitation.

The high failure rate of industry-driven pediatric clinical trials leads to insufficient timely labeling of drugs in children and a lack of scientific evidence, resulting in the persistently high off-label drug use. National clinical trial networks can facilitate collaboration between sites, investigators, and experts, increasing the likelihood of successful trials. Within the conect4children (c4c) network, an Innovative Medicines Initiative 2-funded project, National Hubs hosted by National Clinical Trials Networks were set up across 21 European countries to facilitate the setup and execution of pediatric clinical trials. In this paper, we aim to present the performance metrics of the trial feasibility process as well as learnings and challenges encountered by the Belgian and Dutch Networks in working within the European c4c project. The c4c National Hubs streamline pediatric clinical trials by initiating early country outreach, identifying overlapping studies, recommending quality trial sites, and supporting trial budgeting for both industry and academic settings. To show the impact of Pedmed-NL and Belgian Pediatric Clinical Research Network (BPCRN), internal metrics were collected from 2019 to 2022 on four industry-sponsored and three academic trials performed within the c4c network. Timelines and outcomes of the site identification were collected and analyzed for industry trials. A qualitative analysis was conducted through c4c platforms, sponsor interactions, and stakeholder engagement to evaluate the added value of a research network. In industry-sponsored trials, full feasibility questionnaires were completed within 2 weeks (n = 48), and inclusion rates were up to 80% of clinical sites. Before committing to c4c, 14% of sites were contacted by industry, leading to communication burdens. Utilizing national infrastructure knowledge and therapeutic environment insights helped optimize trial timelines and address feasibility challenges. In addition, national adaptations, such as bilingual staff and site development, played a role in streamlining trial operations in both academic and industry settings. Performance and experiences were similar for both networks. The early-facilitation examples from the c4c trials demonstrated promising metrics for two National Hubs, including optimized start-up timelines and aiding site selection quality. The learnings and challenges of the Belgian and Dutch Networks provided insights for the development of clinical research networks.

Solid-state fermentation for gossypol detoxification and nutritive enrichment of cottonseed cake: A scale-up of batch fermentation process

Gossypol, a toxic polyphenolic compound, limits the use of cottonseed cake (CSC) in animal feed. Different approaches have been employed to detoxify gossypol and improve the nutritive properties of feed. Microbial fermentation improves the nutritive quality of CSC by increasing lysine content and reducing free and bound gossypol. In this study, microbial fermentation was scaled up under batch conditions using a prototype device at the capacity of 40 kg per day. The mixed fungal culture C. tropicalis + S. cerevisiae was used for fermentation. An industrial trial was taken to ascertain the gossypol detoxification efficiency. The fermented CSC obtained under scale-up process had 60 to 80% and 40 to 60% reduction of free and bound gossypol, respectively, compared with raw CSC. The fermented CSC demonstrated an increase in crude protein (4 to 12%) and lysine (0.3 to 0.4%) and decrease in crude fibre (3 to 11%). The fermented CSC met the standards of US Food and Drug Administration in terms of its nutritional property. Thus, the simple method described in this study could be adopted for the production of detoxified CSC for use in the animal feed industry.

Synergistic enhancement of coal slurry water sedimentation and dehydration process using PDMDAAC/PAM

Currently, most coal processing plants use a single pharmaceutical system with large dosage and poor sedimentation effect, resulting in poor subsequent dehydration effect. In this study, poly dimethyl diallyl ammonium chloride (PDMDAAC) as coagulant, and polyacrylamide (PAM) as flocculant, were used for synergistic enhancement of the coal slurry water sedimentation and dehydration process. The best pharmaceutical system was determined by integrating the evaluation indexes in the sedimentation and dehydration process. The mechanism of synergistic enhancement of coal slurry water sedimentation and dehydration process using PDMDAAC/PAM was revealed by analyzing zeta potential, SEM, XPS and FTIR spectroscopy results. Moreover, the Box–Behnken response surface methodology was used to determine the order of significance of coagulant dosage (Cc), flocculant dosage (Cm), and coal slurry water concentration (Cs) on the combined sedimentation and dehydration indexes, and Cm > Cs > Cc. Further, the correlation models between the combined sedimentation and dehydration indexes and each factor were established, the pharmaceutical system was further optimized, and model accuracy was verified. The optimal dosage of PDMDAAC10040 was 2.96 mg/L, and that of PAM2610 was 2.31 mg/L. Then, the industrial trials were conducted at the Tara Trench coal processing plant. Interestingly, after replacing the chemical regime, the efficiency of the thickener and filter press has been significantly improved, resulting in a 33.33% reduction in cost. This research can provide significant theoretical guidance and technical support for industrial applications.

Preparation of biodegradable PLA/PBAT blends with balanced toughness and strength by dynamic vulcanization process

Polylactic acid (PLA) has received significant attention in recent years as a commercially available biodegradable resin. However, its brittleness limits its broader adoption. Blending PLA with another biodegradable resin poly(butylene adipate-co-terephthalate) (PBAT) is a simple strategy to toughen PLA, however, the effect is limited and the tensile strength is generally harmed. In this work, PBAT, initiator BIBP and cross-linker TAIC were initially mixed and then extruded into pre-crosslinked PBAT pellets. Subsequently, the pre-crosslinked PBAT and PLA were melt-blended to create PLA/micro-crosslinked PBAT composites. The effects of different TAIC contents on the degree of PBAT gelation, properties and morphological structure of composites were explored. The results showed that TAIC could effectively improve the mechanical properties of PLA/PBAT, particularly the notched impact strength. When the TAIC content was 0.3 wt% of PBAT, the notched impact strength and elongation at break of PLA/PBAT (7/3) reached 42.26 kJ/m2 and 264.26 %, respectively, which are both far higher than those of the blend without cross-linking (9.37 kJ/m2 and 21.29 %). The composites still exhibited excellent tensile strength (46.23 MPa) and tensile modulus (1676.84 MPa), surpassing those of PLA/un-crosslinked PBAT composites. This enhanced toughening and tensile strength maintaining effect is attributed to the network structure in PBAT and the increased compatibility between PLA and PBAT caused by cross-linking within PBAT and at PLA/PBAT interface. The dynamic vulcanization strategy using an extruder provides a possibility for the large-scale preparation of stiff-tough PLA. Of course, further work, including pilot or industrial trials, is necessary to validate scalability.

Research and engineering practice on space characteristics of gangue slurry filling

The macroscopic characteristics of the fractured space and the microscopic pore features are critical factors determining the effectiveness of gangue slurry backfilling. To identify the key areas for slurry backfilling, a combination of theoretical analysis, simulation experiments, and on-site industrial trials was used to reveal the movement laws of backfilling space overlying the fractured zone. The distribution characteristics of voids available for slurry backfilling within the fractured space were explored, and the interaction between gangue slurry and goaf voids was clarified. A formula for calculating the void ratio in the caved zone was derived, and a model for the distribution of voids in the slurry backfilling space was established. This model identified the main areas where slurry backfilling should be focused, namely the overlapping space between the free accumulation zone and the load-influenced zone. Experimental results demonstrated that the porosity of the collapsed rock mass within the goaf follows a negative logarithmic function along both the dip and strike directions, which was consistent with the theoretical calculations. Through in-situ grouting backfilling experiments on the ground, the feasibility of gangue slurry backfilling in the goaf was verified, and the process of interaction between gangue slurry and goaf voids was elaborated. This process generally involves three stages: initial flow, vertical upwelling, and horizontal diffusion, all of which are closely interconnected. Practical engineering applications of gangue slurry backfilling were carried out in the free accumulation zone and the load-influenced zone at the Huangling No. 2 coal mine. The successful validation of underground gangue slurry backfilling technology demonstrated its feasibility and the correctness of the theoretical approach. This research provides new evidence for environmentally friendly disposal of gangue materials.

Preparation and properties of high molecular weight high temperature resistant carborane polyurethane adhesive

The long-term use temperature of the traditional high-temperature adhesive can only reach about 280 °C, and it cannot be used in extreme environments such as acid and alkali for a long time, which greatly limits its application in aerospace and other fields. Because of its unique three-dimensional structure, carborane has excellent thermal stability and chemical stability. Based on this, first, this article introduced carborane monomer into polyurethane structure, using indirect copolymerization method, Hydroxyl carborane derivative (m8) and conventional polyether diols were used as soft segments. By adjusting the introduction ratio of m8, a series of copolymerized carborane polyurethane (Co-CBR-PU) with controllable thermal and mechanical properties were successfully prepared. Its structure and molecular weight were characterized by FTIR and gel permeation chromatography (GPC), its surface morphology were observed by SEM. The thermal stability and mechanical properties were studied by thermogravimetric test, tensile test and rheological dynamic mechanical analysis test., and its activity, solvent resistance and hydrophobic properties were studied by finger contact method, solvent resistance test and contact Angle test. Second, the high temperature resistant carborane polyurethane adhesive (PUAS) was prepared using Co-CBR-PU as matrix and its adhesion was studied. The results show that a series of Co-CBR-PU has good high temperature resistance, mechanical properties and solvent resistance after adding carborane monomer, and its various properties were optimal when the addition amount of m8 was 15 wt%. The carborane PUAS prepared by using it as the substrate has excellent high temperature adhesion to different adhesive parts. The aim of this study is to reduce the cost of synthesis of carborane polyurethane by regulating the proportion of carborane, and then realize the industrial trial production of high temperature resistant carborane adhesive.

Способ и устройство определения несущей способности фрикционных анкеров

In underground mining, surface reinforcement is a mandatory part of the works. In addition to frame supports, rock bolts and in some cases a combination of the two are now used. The Split Set® friction bolts, referred to as the FRS, i.e. Friction Rock Stabilizers, in the foreign literature, are actively used. More than 11 companies in Russia are currently officially engaged in production of the friction bolts. At the same time, there is a significant difference in the properties of steel used in production of the bolt shafts. Foreign manufacturers recommend the use of steel with the yield strength of 350–400 MPa. This parameter determines the main characteristic of the FRS, i.e. the load-bearing capacity, which can be assessed only after the friction bolt is introduced in the borehole. Until recently, no way has been available to control this parameter of the standard rock bolt. This is explained by the specific feature of the FRS design, i.e. the absence of projecting parts. The load-bearing capacity is determined using specially prepared rock bolts. The purpose of the research was to develop a method and equipment for determining the bearing capacity of the standard FRS bolt using a certified rock bolt tester. The "expanding collet" method of gripping the bolt shaft was adopted. The design of the loading device was based on interpretation of the structural analysis method for mechanical devices. The parametric synthesis of the device elements was carried out on the basis of experimental trials. Experimental and industrial trials of the device confirmed the possibility of determining the load bearing capacity of any FRS bolt. The implementation of the device makes it possible to test the bearing capacity without disturbing the integrity of the excavation and the rock bolt itself.

Underrepresentation of Women in Reduced Ejection Heart Failure Clinical Trials With Improved Mortality or Hospitalization

BackgroundThere are established sex-specific differences in heart failure with reduced ejection fraction (HFrEF) outcomes. Randomized clinical trials (RCTs) based on cardiovascular outcome benefits, typically either reduced cardiovascular mortality or hospitalization for heart failure (HHF), influence current guidelines for therapy. ObjectivesThe authors evaluate the representation of women in HFrEF RCTs that observed reduced all-cause or cardiovascular mortality or HHF. MethodsWe queried Cumulative Index to Nursing and Allied Health Literature, Excerpta Medica dataBASE, Medical Literature Analysis and Retrieval System Online, and PubMed for HFrEF RCTs that reported a statistically significant benefit of intervention resulting in improved mortality or HHF published from 1980 to 2021. We estimated representation using the participation-to-prevalence ratio (PPR). A PPR of 0.8 to 1.2 was considered representative. ResultsThe final analysis included 33 RCTs. Women represented only 23.2% of all enrolled participants (n = 24,366/104,972), ranging from 11.4% to 40.1% per trial. Overall PPR was 0.58, with per-trial PPR estimates ranging from 0.29 to 1.00. Only 5 trials (15.2%) had a PPR of women representative of the disease population. Representation did not change significantly over time. The proportion of women in North American trials was significantly greater than trials conducted in Europe (P = 0.03). The proportion of women was greater in industry trials compared to government-funded trials (P = 0.05). ConclusionsWomen are underrepresented in HFrEF RCTs that have demonstrated mortality or HHF benefits and influence current guidelines. Representation is key to further delineation of sex-specific differences in major trial results. Sustained efforts are warranted to ensure equitable and appropriate inclusion of women in HFrEF trials.

Abstract 14122: Evaluating Gender Diversity in Principal Investigators of Cardiac Electrophysiology Clinical Trials

Background: Importance of diversity in clinical trial participants has been recently highlighted. Though clinical trials led by women principal investigators (PIs) are more likely to enroll diverse participants, the proportion of trials led by women PIs is unknown. Objective: To evaluate gender distribution among PIs who conduct NIH and industry-funded clinical trials in cardiac electrophysiology (EP). Methods: NIH and industry-funded trials in the clinicaltrials.gov registry completed between 1/1/2002 and 12/31/2021 in atrial fibrillation (AF), implantable cardioverter defibrillators (ICDs), pacemakers (PPMs), sudden cardiac arrest (SCA), and ventricular tachycardia (VT) were included. PI names and associated institutions were used to determine gender pronouns on institutional websites or social media. Trials with unidentifiable PI gender were categorized as unknown. Results: 51 NIH-funded and 429 industry-funded trials in AF, SCA, VT, ICDs, and PPMs and 573 total PIs were identified. 128 trials (26.7%) and 123 PIs (21.5%) had unknown PI gender. 16.4% of all trials in which PI gender was known were led by women. 9/49 (18.4%) NIH and 49/295 (16.6%) industry trials were led by women. VT trials had the lowest proportion women-led (NIH: 0/4, 0%; industry: 3/26, 11.5%), whereas PPM trials had the highest proportion women-led in both NIH (3/5, 60%) and all trials (12/48, 22.2%). Of the group with the largest number of trials (AF), 12.9% were women-led (22/170) (Table). Of 450 PIs across all trials whose gender was identified, 14.4% were women. The proportion of women PIs decreased non-significantly over time. Studies between 2002-2011 were 16% women-led, and in 2012 or later this reduced to 13% X 2 (1, N = 450) = 0.81, p > .05. Conclusion: The proportion of cardiac EP clinical trials led by women PIs remains low and has not increased. Urgent efforts are needed to implement strategies to increase leadership roles in clinical trials for women in cardiac electrophysiology.

Abstract 18005: Underrepresentation of Women in Clinical Trials of Heart Failure With Reduced Ejection Fraction

Background: There are established sex-specific differences in heart failure with reduced ejection fraction (HFrEF) outcomes. Randomized clinical trials (RCTs) based on cardiovascular outcome benefits, typically either reduced cardiovascular mortality or hospitalization for heart failure (HHF), and influence current guidelines for therapy. Objectives: To evaluate the representation of women in HFrEF RCTs that observed reduced all-cause or cardiovascular mortality or HHF. Methods: We queried Excerpta Medica dataBASE, Medical Literature Analysis and Retrieval System Online, Cumulative Index to Nursing and Allied Health Literature, and PubMed for HFrEF RCTs that reported a statistically significant benefit of intervention resulting in improved mortality or HHF published from 1980 to 2021. We estimated representation using the participation-to-prevalence ratio (PPR). PPR was calculated based on the proportion of women with HFrEF in the Framingham cohort (40%). A PPR of 0.8 to 1.2 was considered representative. Results: The final analysis included 33 RCTs. All trials except two were mentioned in the 2022 American College of Cardiology/American Heart Association/Heart Failure Society of America Guidelines for the Management of Heart Failure. Women represented 23.2% of enrolled participants (n = 24,363/ 104,972), ranging from 11.4% to 40.1% per-trial. Overall PPR was 0.58, with per-trial estimates ranging from 0.29 - 1.00. Five trials (15.2%) had a PPR of women representative of the disease population. Representation didn’t change significantly by the decade examined. The proportion of women in North American and Multiregional trials was significantly greater than in trials conducted in Europe (p = 0.04). The proportion of women was greater in industry trials compared to government-funded trials (p = 0.05). Conclusions: Women are underrepresented in HFrEF RCTs that have demonstrated mortality or HHF benefits, which may affect the sex-specific generalizability of major trial results. Sustained efforts are warranted to ensure equitable and appropriate inclusion of women in HFrEF trials.

Recovery of Zn from Auger Press Briquettes Made from Steelmaking Sludge

The presence of zinc in metallurgical byproducts poses a constraint on their reutilisation within the realm of ferrous metallurgy. This study delves into the viable prospect of zinc extraction from briquettes manufactured through the auger pressing technique by pyrometallurgical methods. These briquettes are crafted from converter sludge, anthracite, and a multifaceted binding agent. The study encompasses laboratory and industrial trials, spanning the auger pressing technological line, and a tunnel kiln. The consequential outcome of this process yields metallized iron-infused briquettes, effectively purged of zinc content. These briquettes emerge as a propitious raw material option for steelmaking endeavours.

Investigation on close-coupled gas atomization for Fe-based amorphous powder production via simulation and industrial trials: Part I. Melt breakup behaviors during primary atomization

The primary atomization process is simulated by Volume of Fluid (VOF) model and dynamic adaptive mesh method. The influence of melt mass flow rate and atomization pressure on the breakup process is investigated, and the effect of hot gas atomization is also evaluated. The results show that the breakup is insufficient when the melt mass flow rate is larger than 0.075 kg s−1, while the liquid film breakup inducing the nozzle clogging occurs when the melt mass flow rate is too low (0.025 kg s−1). The backflow of droplets occurs at low atomization pressure (1.0 MPa), and various defects (satellite powders, hollow powders and needle-shaped powders) appear when the atomization pressure is larger than 3.0 MPa. Although the breakup efficiency can be significantly improved by increasing the gas temperature, severe deformation of the gas-liquid interface is induced due to the Kelvin–Helmholtz wave and gas-liquid interaction, easily leading to the formation of hollow powders. Besides, the gas-to-melt ratio (GMR) is identified as a simple criterion for predicting primary atomization breakup modes, with liquid film breakup occurring when GMR≥4.4 and "fountain" breakup occurring when GMR≤4.3. In this work, not only the gas-liquid interaction is systematically analyzed by establishing a flow-heat transfer-VOF coupling model, but also the GMR is proposed to predict the breakup mode in the industrial production, which can provide theoretical and methodological guidance for the optimization of atomization operational parameters.

Catheter-directed interventions in acute pulmonary embolism treatment

Abstract: Catheter-based interventions for acute pulmonary embolism (PE) have evolved over the past decades to achieve the benefits of systemic thrombolysis, avoiding though its systemic complications and offering a therapeutic option to a wider spectrum of PE patients who may be contraindicated for thrombolytics. Although numerous observational, retrospective, or small prospective studies have been performed to evaluate the myriad devices used in the preceding years, few are of adequate quality to support widespread use. However, we were seeing an increasing use of catheter thrombolytic and aspiration thrombectomy procedures in both US and Europe. Evidence is building up through several industry trials, and more recently, the PE-Thrombus Removal with Adjunctive Catheter-directed Therapy randomized National Institutes of Health-funded trial was approved to evaluate their benefit over anticoagulation alone in intermediate risk patients. The current evolution of these techniques and existing evidence for their use are summarized.

24 Characteristics and Outcomes of Hospitalized Children by SARS-Cov-2 Lineage: An IMPACT Surveillance Network Analysis

Abstract Introduction/Background Changes in relative virulence of SARS-CoV-2 lineages among children remain poorly understood, yet are important considerations for vaccination and health resource management. Further evidence is needed to assess the burden of severe paediatric COVID-19 due to the Omicron variant. Objectives In this study, we aimed to compare presenting features and disease severity among hospitalized children with COVID-19 in Canada by SARS-CoV-2 lineage. Design/Methods Data were collected during two national surveillance studies: the Canadian Paediatric Surveillance Program (April 2020–May 2021) and the Canadian Immunization Monitoring Program, ACTive (June 2021–May 2022). Cases were included if children were <17 years old and hospitalized for COVID-19 (excluding incidental SARS-CoV-2) at one of thirteen sentinel paediatric hospitals. SARS-CoV-2 lineages were classified as “Ancestral”, “pre-Delta” (Alpha, Beta, or Gamma), “Delta”, or “Omicron” based on genetic sequencing or the predominant lineage across Canada at the time of hospitalization. Severe disease was defined as intensive care, ventilatory or hemodynamic support requirements, organ system complications, or death. Results We identified 1357 children hospitalized with COVID-19, including 254 (18.7%) ancestral, 105 (7.7%) pre-Delta, 175 (12.9%) Delta, and 823 (60.6%) Omicron (Table). Median age at hospitalization was highest for Delta (3.0 years, interquartile range 0.2–11.1) and lowest for Omicron (1.3 years, interquartile range 0.3–5.4; p<0.001). The proportion of children with comorbid conditions did not differ significantly by lineage, ranging from 44.9% (ancestral) to 54.3% (Delta, p=0.149). COVID-19 vaccination (≥1 doses) was received by <5 pre-Delta cases (<4.8%), six Delta cases (3.4%), and 98 Omicron cases (11.9%). Among unvaccinated patients (n=1251), severe COVID-19 was most common among Delta lineages (34.3%) versus other lineages (24.0% ancestral, 22.3 pre-Delta, 24.8% Omicron; p=0.049). Conclusion Our results show more children were hospitalized during Omicron waves than all other waves combined, though Delta was relatively more severe. These findings underscore the substantial burden of Omicron in children. Potential competing interests Jesse Papenburg received consultant fees/honoraria from Astra-Zeneca, Merck, and Seegene, and is site PI for industry trials by Astra-Zeneca, MedImmune, Merck, and Sanofi (all outside current work). Rupeena Purewal is a consultant for Verity Pharmaceuticals. Manish Sadarangani has been an investigator on projects funded by GlaxoSmithKline, Merck, Moderna, Pfizer, Sanofi-Pasteur, Seqirus, Symvivo, and VBI Vaccines (all outside current work). Fatima Kakkar received salary support from the FRQS Chercheur Boursieurs Program, and honoraria from the Association des Pédiatres du Québec. Shaun Morris has received honoraria for lectures from GlaxoSmithKline and was a member of ad hoc advisory boards for Pfizer Canada and Sanofi Pasteur (all outside current work). No other competing interests are declared.

Regulatory Guidance on Randomization and the Use of Randomization Tests in Clinical Trials: A Systematic Review

Randomization is a critical aspect of the clinical trial. Regulatory guidance plays a role in clinical research. Randomization tests provide valid methodology for statistical inference. In the present paper, we intended to survey: (a) information contained in regulatory guidance on randomization; and (b) the use of randomization tests in trials supporting marketing applications. This systematic review used the Cortellis Regulatory Intelligence database (IDRAC). For (a), of n = 156 guidance documents, nine provided recommendations on randomization methods. For (b), n = 48 trials (52 submissions) employed randomization tests. 40 (83.3%) were phase III trials, 31 (64.6%) employed dynamic allocation. Randomization test was the primary in 5 (10.4%), and sensitivity analysis in 34 (70.8%) trials. Furthermore, randomization tests were performed when treatment allocation was not according to plan (4 (8.3%)), or violations of model assumptions (5 (10.4%)) were observed. Overall, there are sparse recommendations on randomization in current regulatory guidance, with little mention of recently developed methods which might outperform current practice in certain contexts. Greater adoption of such methods in pharmaceutical industry trials may lead to a better shared sense between regulators and trial sponsors on their appropriate use. Randomization tests are employed with greater frequency, reflecting increased appreciation of the validity and value of randomization tests.

Deterioration mechanism of Al2O3–MgO refractory castable in RH refining ladle

The purpose of this work was to investigate the deterioration mechanism of an optimized Al2O3–MgO refractory castable during industrial trials. After structural optimization, the average corrosion rate of every cycle deceased to 0.29 mm/cycle from 0.46 mm/cycle. Corroded microstructure of the optimized Al2O3–MgAl2O4 refractory castable after server 195 cycles was explored. It was indicated that the structural optimization led to an approximate 36% improvement in corrosion resistance than that of comparison one. An adhered slag layer comprising of (Fe, Mg)Al2O4 spinel was observed on the refractory's surface. Iron beans and iron/manganese oxides mainly occurred in the reaction layer, and several penetrating cracks occurred at the corroded interface which would cause potential structural spalling for refractory lining. Based on the observed microstructural characteristics, a corrosion mechanism of refractory lining in a commercial ladle was proposed.