Steel reinforced self-compacting concrete (SCC) cantilever beams: bond behaviour in poor condition zones

Previous investigations carried out on reinforced self-compacted concrete (SCC) beams have reported contradictory results on reinforcement bond behaviour occurring in the zones defined for good bond conditions according to Eurocode2. Cantilevered SCC beams’ critical upper tension reinforcement bond behaviour has previously had limited reporting. In this study, the bond behaviour in normally vibrated concrete (NVC) and self-compacted concrete (SCC) in poor condition s zones are compared and the differences are highlighted. The effect of four parameters , including (i) concrete type (SCC and NVC), (ii) characteristic strength of SCC, (iii) lap splice length, and (iv) depth of concrete cover for the reinforcement is investigated. It was found that for the studied beams, increasing splice length improved the energy absorption and changed the failure mode to a more ductile manner even at the poor bond conditions zones. The maximum measured steel strains in SCC beams in the lap splice zones, were higher than those for NVC specimens. The mean bond stress values, for SCC beams with 25% and 50% lap splice lengths, were higher than those of NVC beams, with the same lap splice lengths, by 16% and 13%, respectively. The results of the current study showed that the empirical equations from the literature overestimated the bond strength of the splice lap length for cantilever upper steel in SCC beams with long splices which agrees with the state of the art as these equations were developed originally for short anchorage lengths

Predictive Markers for Hepatocellular Carcinoma Development in Patients with Chronic Hepatitis C Virus Genotype4a

Background: Egypt has the highest prevalence of hepatitis C virus worldwide. Monitoring hepatitis C-infected patients for hepatocellular carcinoma development is an important clinical issue to diagnose these patients during the potentially curable early-stage of disease. This study aims to evaluate the role of N-terminal procollagen III, matrix metalloproteinase- 2, tissue inhibitor of matrix metalloproteinase-1, alpha-fetoprotein, and conventional liver function tests as predictors of hepatocellular carcinoma development upon long-term followup of non-responding hepatitis C virus patients. Methods: The study included 850 treatment-naïve hepatitis C virus genotype 4a adult patients; after treatment, 360 achieved sustained viral response while 490 did not. Nonresponding patients had a 5-year rate for hepatocarcinogenesis of 8.4% and a 10-year rate of 27.5%. N-terminal procollagen III, matrix metalloproteinase-2, tissue inhibitor of matrix metalloproteinase-1, alpha-fetoprotein, and conventional liver function tests were evaluated in all patients before and after treatment, and after hepatocellular carcinoma development. The study also included a group of 50 hepatocellular carcinoma patients who were negative for hepatitis C and hepatitis B viruses, and a group of 50 healthy subjects as controls. Results: The non-responders had significantly higher age, stage, grade, viral load, alanine aminotransferase, and aspartate aminotransferase than responders. Also N-terminal procollagen III, matrix metalloproteinase-2, tissue inhibitor of matrix metalloproteinase-1, and alphafetoprotein were significantly higher in non-responders; after treatment they decreased in responders. In non-responders they remained higher than the control. The most significant risk factors for hepatocellular carcinoma development in non-responding hepatitis C virus patients were male gender and increased age, stage, grade, aspartate aminotransferase, Nterminal procollagen III, and tissue inhibitor of matrix metalloproteinase-1. Patients with viral-hepatocellular carcinoma were of significantly lower age, higher grade, stage, γ-glutamyltransferase, N-terminal procollagen III, and matrix metalloproteinase-2 than non-viral hepatocellular carcinoma patients. Percent positive N-terminal procollagen III, tissue inhibitor of matrix metalloproteinase-1, and alpha-fetoprotein were significantly higher in viral hepatocellular carcinoma patients. Conclusion: Data suggest that high N-terminal procollagen III and tissue inhibitor of matrix metalloproteinase-1levels after treatment might be particularly important as markers of hepatitis C virus-non-responding patients who are at higher risk of developing hepatocellular carcinoma, especially in older males with high stage and grade liver disease. However, studies of larger scale are needed to verify this suggestion

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Sudden Development of Subcutaneous Nodules Shortly after Radioiodine Treatment for Thyroid Cancer Caused by Self-Limiting Sarcoidosis

Background: Sarcoidosis is a multisystemic disease producing non-caseating granulomas. The aetiology and pathogenesis are unknown. We herewith report an atypical case of cutaneous sarcoidosis.Case presentation: A 50-year-old female presented with an onset of multiple subcutaneous nodules on her 4 limbs. These nodules appeared concomitantly with the initiation of radioactive iodine therapy for papillary thyroid cancer. These nodules were not obvious on inspection of the skin, but easily felt on palpation.The biopsy of the subcutaneous nodules revealed hypodermic non-caseating granulomas consistent with sarcoidosis. The patient underwent an 18F-fluorodeoxyglucose positron emission tomography (PET) scan study that revealed, besides the subcutaneous nodules, multiple hypermetabolic mediastinal lymphadenopathies and cervical adenopathies. Biopsy of the mediastinal lymphadenopathy showed neither granulomas nor neoplastic cells. Cervical biopsy revealed neoplastic cells of thyroid origin. Laboratory tests were normal. Bronchoalveolar lavage showed a normal CD4/CD8 T-cell ratio. A diagnosis of cutaneous sarcoidosis was established, as well as a recurrence of the cancerous disease. The subcutaneous nodules regressed spontaneously in the absence of any treatment.Discussion and conclusion: Sarcoidosis is a multisystemic disease of unknown origin. This case illustrates an uncommon occurrence of sarcoidosis, triggered by radioactive iodine therapy. Radioiodine may lead to immunological changes, especially affecting the Th1/Th2 ratio, which may promote the emergence of sarcoidosis in genetically predisposed patients. There is still much to discover to fully understand the pathogenesis of sarcoidosis

Typical features of constrictive pericarditis in a woman admitted for ascites.

info:eu-repo/semantics/publishe

Vertebral Artery Perforation as a Periprocedural Complication of Coronary Angiography.

Coronary angiography is a routinely performed intervention, with radial catheterization the recommended approach. We report a unique case of perforation of the right vertebral artery following coronary angiography that was successfully treated by endovascular management. (Level of Difficulty: Advanced.).info:eu-repo/semantics/publishe

Effect of partial replacement of coarse aggregate by polystyrene balls on the shear behaviour of deep beams with web openings

Thirteen specimens were experimentally tested under single midspan concentrated loads to study the shear behavior of lightweight concrete (LWC) and normal weight concrete (NWC) deep beams with web openings. In this research, the term LWC refers to the concrete obtained by partially replacing aggregate by polystyrene foam balls not the concrete containing lightweight aggregate. This resulted in a weight reduction of LWC beams in this research by approximately 30 % compared to NWC compartments. The studied variables were the dimensions and location of openings, transverse reinforcement ratio, and shear span to depth ratio (a/d). It was found that the overall shear behavior and failure mode for LWC deep beams are comparable to those of the NWC specimens. This is very promising and encouraging to build lighter deep beams of similar structural behaviour as that of NWC deep beams. Dimensions of the openings have a significant effect on the behaviour of failure and shear strength of LWC and NWC deep beams. It was found that increasing the depth of the opening from 20 % to 40 % of the beam depth led to a reduction in the ultimate load by up to 46.4 %. Finite element modelling of the test beams was carried out to verify numerical results versus experimental work and both were very well correlated. In addition, a parametric study was conducted to assess the effect of internal stiffening around openings in deep beams. The maximum enhancement in the shear capacity was approximately 30 % for beams, internally strengthened by additional reinforcement on the perimeter of openings compared to the beams without any reinforcement around the openings. Strut-and-Tie model (STM) was carried out as a rational approach to predict the shear behaviour of studied beams. It was found that STM underestimates the shear of the studied beams compared to experimental results for different tested beams but the agreement between both of them was acceptable. It is recommended that the depth of opening should not exceed 20 % of the depth of the deep beam and if the depth of opening is more than that or lies in the shear span it is highly recommended to strengthen the opening internally by additional reinforcement around its perimeter

Structural behaviour of polystyrene foam lightweight concrete beams strengthened with FRP laminates

Lightweight concrete (LWC) is one of the most important building materials nowadays. Many research studies were focused on LWC produced using lightweight aggregates. However, limited work was cited for LWC produced using polystyrene beads. In this study, LWC beams strengthened with carbon fibre reinforced polymer (CFRP) and glass fibre reinforced polymer (GFRP) were experimentally tested to investigate the improvement in their flexural and shear behaviours. LWC in this investigation was achieved by partial replacement of normal aggregate by polystyrene beads and resulted in approximately 30 % less weight compared to Normal weight concrete. Fourteen Reinforced Concrete (RC) LWC beams of 100 mm by 300 mm cross-section having an overall length of 3250 mm were tested under four-point bending. These beams were designed, detailed, and tested to obtain flexural and shear mode of failure. These beams were divided into two groups based on the intended failure mode. In each group, six beams were strengthened using CFRP and GFRP laminates while the remaining one beam was used as control. The tested parameters were the type of FRP, the width of the laminates used in shear strengthening, and the number of layers used in flexural strengthening. It was found that strengthening of LWC beams using CFRP and GFRP layers resulted in increasing the loading capacity and decreasing deflection as compared to control. The strengthening with CFRP and GFRP is also suitable in reducing the crack width and crack propagation which is more significant in LWC beams. The experimental results were also compared with the expressions in codes for forecasting the strength of LWC beams and it was that these expressions are compatible with the experimental results