Exploring the Effect of In-plane Tensile Forces on the Two-way Shear Strength: review, comparative study and future works

Two-way shear failure of slabs is a sudden one, which has catastrophic outcomes. Slabs with large spans may be subjected to in-plane tensile forces due to thermal or earthquake loading. There is a lack of agreement between various design codes regarding the significance of in-plane tensile forces on the two-way shear strength. Two-way shear failure of slabs is a sudden one, which has catastrophic outcomes. Slabs with large dimensions may be subjected to in-plane tensile forces due to restraint or earthquake loading. There is a lack of agreement between various design codes regarding the significance of in-plane tensile forces on the two-way shear strength. The purpose of this study is to explore, propose a simplified two-way shear strength model, which includes the effect of in-plane tensile forces on the strength. A review for the experimental investigations, existing models, design codes for two-way shear of slabs is presented, with emphasis on in-plane tensile forces. The loading method used in the current experimental testing is misleading, where the two-way shear and the in-plane forces are independent. A comparative study was conducted between the existing formula and design codes for this case. The comparison between different codes with the experimental results show that the new proposed Eurocode design code was found to be the most accurate one. However, it did not include the effect of the in-plane tensile forces in a physically sound manner. In addition, more full testing of concrete slabs under combined two-way shear and tensile forces are required to refine this existing two-way shear design code provisions or develop new formulas or mechanical models

Effect of Blast Loading on Seismically Detailed RC Columns and Buildings

Explosions caused by standoff charges near buildings have drastic effects on the internal and external structural elements which can cause loss of life and fatal injuries in case of failure or collapse of the structural element. Providing structural elements with blast resistance is therefore gaining increasing importance. This paper presents numerical investigation of RC columns with different reinforcement detailing subjected to near-field explosions. Detailed finite element models are made using LS-DYNA software package for several columns having seismic and conventional reinforcement detailing which were previously tested under blast loads. The numerical results show agreement with the published experimental results regarding displacements and damage pattern. Seismic detailing of columns enhances the failure shape of the column and decrease the displacement values compared to columns with conventional reinforcement detailing. Further, the effect of several modeling parameters are studied such as mesh sensitivity analysis, inclusion of air medium and erosion values on the displacements and damage pattern. The results show that decreasing the mesh size, increasing erosion value and inclusion of air region provide results that are very close to experimental results. Additionally, application is made on a slab-column multistory building provided with protective walls having different connection details subjected to blast loads. The results of this study are presented and discussed. Use of a top and bottom floor slab connection of protective RC walls are better than using the full connection at the four sides to the adjacent columns and slabs. This leads to minimizing the distortion and failure of column, and therefore it increases the chance of saving the building from collapse and saving human lives. Doi: 10.28991/cej-2021-03091733 Full Text: PD

Post-Surgical Repair of Cleft Scar Using Fractional CO2 Laser

BACKGROUND: Postoperative scarring is a common cause of patients dissatisfaction. Several modalities have been developed to overcome such a problem following surgical repair. Despite precise surgical technique, still, some scars would remain over the time, mostly due to the weak formation or inadequately replaced collagen fibres in the underneath dermis especially those following unilateral or bilateral cleft lip repair surgery.AIM: of this study is to evaluate whether a 10,600 nm fractional ablative carbon dioxide (CO2) used early during the healing period would result in better postoperative scars.METHODS: In the present study six patients complained from cleft lip scars resulting from lip revision surgery. Each patient had six fractional ablative CO2 laser sessions for treatment along six months to obtain a complete collagen cycle. Vancouver Scar Scale VSS was used as a method of evaluation of the scar using 4 points scale evaluating vascularity, pliability, thickness & colour of the skin and Visual Analogue Scale VAS from (0-10) was used to assess the severity of pain as well as a survey questionnaire for the rate of patient’s satisfaction. Also, digital clinical photos assessment before&after were compared.RESULTS: Patients expressed a significantly greater degree of satisfaction with the treatment using a subjective 4-point scale. All patients observed dramatic improvement in their lip scars after FCO2 laser sessions following their surgeries with the better psychological state. The assessment was done by clinical observation according to VSS before (9.17 ± 2.2) while after (3.33 ± 1.9) with a highly significant P value <0.001 and VAS for the rate of pain & satisfaction that ranged from (8.0 ± 0.9) as well as series of photos taken before and after the procedure. No long-term complications were noted however patients complained of annoying pain during the session as well as crust formation that lasted up to 5 days after surgery. In the present study, we introduce the effectiveness of ablative fractional 10,600 nm CO2 laser for treatment of postoperative cleft lip scar after secondary surgical cleft repair rather than ablative CO2 due to its reported complications such as postoperative infection, erythema and pigmentary changes along with prolonged downtime healing. In the current study, we chose early laser treatment within the first six months before complete collagen organisation which will be easier to manage the older scars. Patients mostly complained about the pain during the session as well as dark-coloured crust formation post session that stayed from 3-5 days however they all observed a massive improvement of their scars following treatment protocol.CONCLUSION: Facial wounds sutured in layers heal in a good manner. Patients prefer early treatment with a fractional CO2 ablative laser for postoperative surgical scars. The use of a CO2 fractional laser is safe and effective also causes high patients satisfaction

Are Thermal Attacks Ubiquitous? When Non-Expert Attackers Use Off the Shelf Thermal Cameras

Recent work showed that using image processing techniques on thermal images taken by high-end equipment reveals passwords entered on touchscreens and keyboards. In this paper, we investigate the susceptibility of common touch inputs to thermal attacks when non-expert attackers visually inspect thermal images. Using an off-the-shelf thermal camera, we collected thermal images of a smartphone's touchscreen and a laptop's touchpad after 25 participants had entered passwords using touch gestures and touch taps. We show that visual inspection of thermal images by 18 participants reveals the majority of passwords. Touch gestures are more vulnerable to thermal attacks (60.65% successful attacks) than touch taps (23.61%), and attacks against touchscreens are more accurate than on touchpads (87.04% vs 56.02%). We discuss how the affordability of thermal attacks and the nature of touch interactions make the threat ubiquitous, and the implications this has on security

One-year outcomes of percutaneous coronary intervention in native coronary arteries versus saphenous vein grafts in patients with prior coronary artery bypass graft surgery

Background: Patients with prior coronary artery bypass graft (CABG) surgery often require percutaneous coronary intervention (PCI). Data are still limited in regards to the outcomes of native saphenous vein graft (SVG) PCI after CABG. Methods: We performed a retrospective study in a tertiary reference cardiac center of consecutive patients who underwent PCI after CABG. The data were collected for patients who underwent either native or graft PCI from January 2008 to December 2018. Arterial graft PCIs were excluded. Multivariable Cox regression analysis with propensity matching was performed, and major adverse cardiac events (MACE) outcomes including death or myocardial infarction (MI) or revascularization were assessed at 1-year after each index procedure. Results: A total of 435 PCI were performed in 401 patients (209 had native PCI and 192 had graft PCI). Target lesions were classified as following: 235 (54%) native coronary arteries and 200 (46%) SVG. Propensity matching resulted in 167 matched pairs. In multivariable Cox regression graft PCI relative to native PCI was an independent risk factor for MACE (hazard ratio [HR] 1.725, 95% confidence interval [CI] 1.049–2.837) which was primarily driven by increased incidence in revascularization (HR 2.218, 95% CI 1.193–4.122) and MI (HR 2.248, 95% CI 1.220–4.142) and with no significant difference in mortality (HR 1.118, 95% CI 0.435–2.870). Conclusions: Compared with native coronary PCI, bypass graft PCI was significantly associated with higher incidence of MACE at 1-year and this was mainly driven by MI and revascularization

The Impact of Restrictive Versus Conservative Intraoperative Fluid Strategies upon the Renal Outcome in Colorectal Surgeries. A Randomized Controlled Trial

Background: intraoperative fluid handling has a lot of concerns upon the postoperative organ function. One of the most sensitive organs which could be affected is the kidney. Objectives: We conducted this trial to address the impact of restrictive vs. conservative fluid approaches on postoperative renal complications, hemodynamics and hospital stay. Patients and methods: Prospective, randomized, double-blind placebo-controlled trial at Assiut University Hospitals. The study included 60 adult patients with American Society of Anesthesiologists (ASA) grade II-III undergoing elective colorectal surgery with an expected operative duration of at least two hours. Grouping was based upon the intraoperative fluid management Group (R): 6 mL/kg/h. of lactated ringer (LR), Group (C): 12 mL/kg/h. of LR. The preoperative serum Neutrophil gelatinase-associated lipocalin (NGAL) level (basal value) then by the 2nd and 24th postoperative hours, KDIGO (Kidney Disease: Improving Global Outcomes), serum urea and creatinine were documented by the end of 1st and 2nd postoperative days. Intraoperative hypovolemia events were noted as well. Results: serum NGAL has increased >149 ng/mlin three patients within group C, and two patients within group R; however, the difference was statistically insignificant p= 0.5. KDIGO showed significant difference between the two groups, with higher number of patients in the group R with p= 0.043. Serum urea and creatinine, intraoperative hypovolemic episodes showed insignificant differences between groups. Conclusion: no evident difference between restrictive and conservative intraoperative fluid strategies was noticed upon the early postoperative serum NGAL and other systems complications in patients undergoing major colorectal surgeries

Effects of Antioxidant Supplements on the Survival and Differentiation of Stem Cells

Although physiological levels of reactive oxygen species (ROS) are required to maintain the self-renewal capacity of stem cells, elevated ROS levels can induce chromosomal aberrations, mitochondrial DNA damage, and defective stem cell differentiation. Over the past decade, several studies have shown that antioxidants can not only mitigate oxidative stress and improve stem cell survival but also affect the potency and differentiation of these cells. Further beneficial effects of antioxidants include increasing genomic stability, improving the adhesion of stem cells to culture media, and enabling researchers to manipulate stem cell proliferation by using different doses of antioxidants. These findings can have several clinical implications, such as improving neurogenesis in patients with stroke and neurodegenerative diseases, as well as improving the regeneration of infarcted myocardial tissue and the banking of spermatogonial stem cells. This article reviews the cellular and molecular effects of antioxidant supplementation to cultured or transplanted stem cells and draws up recommendations for further research in this area

Contemporary management of Patent Foramen Ovale: A multinational survey on cardiologists' perspective

Objectives. The purpose of our survey is to analyze the clinical approach used by interventional and imaging cardiologists to diagnose, treat, and follow-up patients with PFO-related left circulation thromboembolism in different parts of the world with particular emphasis on adherence to current guidelines. Background. Firm guidelines do not cover many aspects of PFO-related patient care. Consequently, very disparate approaches exist among clinicians in the real-world. Methods. A 24-item electronic questionnaire was sent directly to experienced cardiology specialists practicing at consultant/attending positions directly involved in PFO closure management in the United States, United Kingdom, Gulf countries, and other countries. There were no unanswered questions. Responses were recorded between October 2019 and July 2020. Results. Seventy-one responses were obtained: 31 from the UK, 19 from the US, 16 from Gulf countries, 2 from Poland, and 1 response from Australia, Italy, and Switzerland. The overall response rate was 76%. Significant differences between regions were noted in the duration of ECG monitoring during the diagnostic process, PFO closure for left circulation thromboembolism other than stroke/transient ischemic attack, and intraoperative use of intracardiac echocardiography. A similar pattern was noted in the lack of routine screening for thrombophilia and the use of the long-term single antiplatelet therapy. Conclusions. The study shows a vast spectrum of opinions on the optimal approach to PFO closure with significant differences between the US, UK, and Gulf countries. The results stress the need for systematic, high-quality data on the diagnostic work-up and follow-up strategies to inform the standardized approach