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Despite significant advances in metallurgy and the potential to create high and ultra-high-strength steel, all international specifications for steel design provide little information about the limits of slenderness for high-strength steel sections (HSSs) and don’t provide anything about the design of ultra-high-strength steel sections (UHSSs). The current international steel codes such as AISC 360-16 and EC3 can be applied only to steel grades up to S690 and S460, respectively, according to their limitations. These approaches for normal-strength steel are used for HSSs and UHSSs without extensive studies to determine their accuracy in these cases. Therefore, it is one of the main objectives of this study. The behavior of high and ultra-high-strength steel circular hollow sections under axial compression load is studied in this research. Sixteen nonlinear finite element (FE) models were generated to replicate stub column tests that were experimentally tested by others in previous research. Hence, a parametric study was conducted using forty FE models developed to investigate the local buckling behavior under various slenderness ratios comprehensively. The developed models covered slenderness ratios ranging from 20 to 1226 and steel grades S460 and S1100 with yield stress equal to 460 MPa and 1152 MPa, respectively. The FE results were combined with 105 previously collected experimental results to assess the applicability of existing codified design methodologies in the Euro code and the North American codes of cold-formed circular hollow sections (CHSs). Based on the results of this study, new cross-section slenderness limits and new design equations for more efficient simple designs were presented for circular hollow sections of HSSs and UHSSs and compared with the results of experimental tests and FE models.

Cold-formed steel sections are becoming popular for different steel structures, because they have a high resistance against different straining actions, with a minimal weight compared with hard steel sections. Recently, perforated cold-formed steel (PCFS) sections have been used in many applications, such as perforated upright storage racks. Experimental research into the behavior of steel storage rack uprights subjected to axial compression is presented in this paper. First, tensile tests determined the material qualities of the cold-formed steel uprights. Then, seventeen perforated specimens were examined under axial compression, with five different cross-sections, three different web heights and thicknesses, and varying lengths. The study’s goals were to find out how perforations affect the performance and failure mode of steel storage rack uprights, to discuss the interaction of distortional and global buckling, and to verify the accuracy of using the direct strength method (DSM) for predicting the ultimate strength before failure in buckling interactions for perforated uprights. It was found that the failure modes of perforated specimens with stiffeners generally cannot be well predicted using the direct strength method. However, when the modifications proposed by Xianzhong Zhao et al. are used, the accuracy is acceptable.

Because of its numerous advantages, the steel plate girder with the corrugated web is widely employed in a variety of applications. It has great resistance to shear buckling when compared to another flat web girder of the same steel weight. Some of the present standards and specifications such as the Euro-code include design approaches for determining the shear buckling strength of the corrugated web girders. This research examines the resistance of corrugated web girders to shear buckling, investigates their behavior, and checks the accuracy of the Euro-code equations. ANSYS is used to do the nonlinear finite element analysis. This study considers the effects of several parameters (web thickness, web height, corrugation angle, corrugation breadth, and corrugation shape). It is found that the shear buckling resistance for girders with corrugated webs is increased due to the increase in web thickness, web height, corrugation angle, corrugation depth, and the number of corrugation waves along the girder span while it decreased due to the increased of the corrugation width. The main conclusion is the accuracy of using Euro-code equations for trapezoidal corrugated webs is good but it is must be modified in the case of girders with triangular or rectangular corrugated webs. [ABSTRACT FROM AUTHOR]

This paper investigates the application of electrochemical ballizing (ECB) in finishing holes which are produced by conventional machining processes. A special test rig has been designed where the electrolyte is pumped through an initial hole of hardened steel workpieces. The front of the tool is of spherical shape, and therefore the electrolyte distribution is regular. A computer implement model is proposed for accurately estimating the thickness of the removed workpiece surface. Experimental results have been found to agree with the estimated values. The surface roughness measurement and scanning electron microscopy indicate the improvement in the surface characteristics of holes. [ABSTRACT FROM AUTHOR]

The use of tubular cathodes considerably widens the technological possibilities in ECM of large-size components, especially if the allowance (area to be machined) is removed in solid form. The present paper reports experimental investigations on this technique in the electrochemical cutting operation. Experiments were carried out to study the influence of machining parameters such as feed rate, applied voltage, electrolyte conductivity and electrolyte flow-rate on the width of cut, electrolysing current and volumetric metal removal rate. Experiments were planned on the basis of response-surface methodology (RSM) technique. Three mathematical models correlating process parameters and their interactions with response parameters have been achieved. These models can be used in selecting optimum process parameters for obtaining the desired controlled width of cut with restricted consumed current. [ABSTRACT FROM AUTHOR]

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Background Restoring endodontically treated teeth has long posed a challenge for clinicians. The endocrown (EC) is an innovative and conservative restoration designed for teeth with severely damaged coronal structures. ECs offer performance that is equivalent to or even exceeds that of traditional post-core-crown treatments. Purpose This web-based cross-sectional survey aimed to evaluate the level of knowledge and practical experience regarding ECs as post-endodontic prostheses among dental students and practitioners in Libya. Methods A 22-item structured questionnaire was created using Google Forms and distributed to final-year students, interns, faculty at the College of Dentistry at Sirte University, and practicing dentists in Libya. The sample comprised 290 participants. The questionnaire was divided into three sections: the first assessed demographic variables such as gender, education level, country of graduation, and workplace; the second evaluated knowledge of ECs through 11 questions; and the third focused on EC practice, also comprising 11 questions. Statistical analysis was conducted using IBM SPSS Statistics for Windows, Version 21.0 (Released 2012; IBM Corp., Armonk, NY, USA). Results A total of 50.7% of participants indicated that EC restorations are suitable for molar teeth, 41.4% noted that a butt joint finish line is used for EC preparation, and 66.9% preferred all-ceramic materials for ECs. Nearly 72.8% reported that computer-aided design/computer-aided manufacturing technology is employed for EC fabrication. Additionally, 61.7% agreed that EC designs offer higher fracture resistance compared to conventional crowns. Despite this, 64.5% of participants had not cemented an EC in their clinic in recent years. Significant differences in knowledge and practice regarding ECs were observed across various factors, including gender, education level, country of graduation, and workplace. Conclusion Most participants demonstrated an acceptable level of knowledge and practical experience with EC restorations. Therefore, incorporating ECs as a major topic in the postgraduate prosthodontics curriculum is recommended., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Ethical Committee of National Center of Disease Control, Ministry of Health, Libya issued approval NBC: 002. H-23.22. The Ethics Committee does not have any ethical objections to the conduct of the research project. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Abu Sittah et al.)

Purpose: In pediatric population, large soft tissue defects occur in avulsion injuries. In addition to the challenges of primary surgical therapy, elasticity, appearance and function of the scar in children are of crucial importance, especially in the context of body growth. So far various flaps, plasties, skin grafts and dermal substitutes have become established, although infections and skin shrinkage remain challenging. In 2020, a new skin substitute material-NovoSorb® Biodegradable Temporizing Matrix (BTM)-was introduced in Europe for temporary wound closure and tissue regeneration. The aim of this study was to evaluate the value of BTM in pediatric patients., Methods: The study included all children treated with BTM after traumatic soft tissue defects following limb avulsion injuries between June 2021 and June 2023 at a university hospital., Results: 7 patients with limb avulsion injuries were treated with BTM, 4 boys, 3 girls. Mean age was 6.5 years (2-11 years) at the time of BTM placement. 4/7 had concomitant fractures. BTM was used successfully in all cases, infection did not occur, skin shrinkage was seen in one case. Split thickness skin graft (STSG) after BTM application was performed in average after 33 days (26 to 39 days). Limitations of this study were highlighted., Conclusion: BTM is a promising alternative for reconstruction of complex trauma extremity wounds in children following avulsion injuries, even in cases of concomitant bone injuries. Interpretation may be limited by sample size., (© 2024. The Author(s).)

Background: Oral manifestations serve as important indicators of human immunodeficiency virus (HIV) infection, and dental healthcare practitioners play a pivotal role in preventing and managing HIV. This study aims to assess and compare the knowledge and attitude of dental assistants and dental hygienists concerning people with HIV/acquired Immunodeficiency syndrome (AIDS) patients in Jeddah province of Saudi Arabia., Materials and Methods: This cross-sectional survey enrolled 160 dental hygienists and assistants practicing in Jeddah. Data was collected using a pretested, self-administered questionnaire comprising 50 questions that investigated knowledge about HIV/AIDS, awareness of HIV-associated oral and periodontal lesions, understanding of HIV transmission routes, and attitudes toward people with AIDS., Results: In the study, 120 (75.0%) participants correctly recognized that individuals with HIV may appear healthy, while 123 (76.9%) participants admitted that HIV carriers have lower resistance to other diseases. Additionally, 126 (78.8%) participants confirmed an association between the virus and oral lesions, and 137 (85.6%) participants were aware of HIV transmission through blood. Moreover, 150 (93.7%) participants expressed their willingness to support, treat, and assist patients with AIDS, while only 10 (6.3%) participants expressed unwillingness. Notably, no statistically significant differences were found between dental assistants and hygienists in their knowledge and attitudes toward HIV/AIDS and people with AIDS., Conclusion: This study demonstrated that dental hygienists and assistants possess good general knowledge regarding HIV/AIDS and are well-informed about the disease's transmission routes. Moreover, a significant majority endorses the importance of treating and supporting AIDS patients., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Bamashmous et al.)

Background: Dyspnoea is a common complaint that often remains unexplained with no diagnosis and poor management despite extensive, repetitive and costly testing. Invasive cardiopulmonary testing has been used in the evaluation of dyspnoea, however, its role is not yet well defined. We sought to perform a systematic review of the literature looking at the role of invasive cardiopulmonary testing in the evaluation of chronic dyspnoea and/or exercise intolerance., Methods and Results: We performed a literature review in accordance with PRISMA, analysing articles published in peer-reviewed journals between January 1st 1985 and January 31st 2020, available in 3 databases. The aim was to identify randomised and non-randomised clinical studies that focussed on the utility of invasive cardiopulmonary exercise test in the evaluation of dyspnoea. Emphasis was placed on studies that noted the use of exercise stress testing with the concomitant use of right heart catheterisation to evaluate hemodynamics as part of the work up for dyspnoea. We identified 6 retrospective studies that assessed the use of exercise hemodynamics to identify the aetiology of dyspnoea., Conclusion: Invasive cardiopulmonary exercise test is a useful tool for identifying the cause of unexplained dyspnoea. It can be helpful in early recognition and prognostication of patients with heart failure with preserved ejection fraction and pulmonary hypertension. It has also shown to be beneficial for constructing a multidisciplinary approach to chronic dyspnoea.