High Strain Rate Response of Adhesively Bonded Fiber-Reinforced Composite Joints A Computational Study to Guide Experimental Design

Adhesively bonded carbon fiber-reinforced epoxy composite laminates are widely used in aerospace applications. During a high energy impact event, these laminates are often subjected to high strain rate loading. However, the influence of high strain rate loading on the response of these composite joints is not well understood. Computational finite element (FE) modeling and simulations are conducted to guide the design of high strain rate experiments. Two different experimental designs based on split Hopkinson bar were numerically modeled to simulate Mode I and Mode II types loading in the composite. In addition, the computational approach adopted in this study helps in understanding the high strain rate response of adhesively bonded composite joints subjected to nominally Mode I and Mode II loading. The modeling approach consists of a ply-level 3D FE model, a progressive damage constitutive model for the composite material behavior and a cohesive tie-break contact element for interlaminar delamination

In Situ Deformation Characterization of Density-Graded Foams in Quasi-Static and Impact Loading Conditions

Digital image correlation is utilized to characterize deformation and strain fields developed within the layers of density-graded multilayered foam structures subjected to uniaxial quasi-static and dynamic compression. Three-layered graded structures fabricated from rigid polyurethane foams with nominal densities of 160, 240, and 320 kg/m³ are subjected to both quasi-static and dynamic loading. The quasi-static measurements show that, irrespective of the loading direction, the densification initiates in the lowest density layer and propagates into other layers later once the first layer is fully densified. The deformation mechanisms are seen to be different in the case of dynamic loading conditions compared to the quasi-static loading. The deformation mechanism, in the case of dynamic loading, depends on the sample orientation relative to the direction of the applied load. In cases where the higher density layers are impacted, the propagation of the elastic and compaction waves leads to partial deformation of the lowest density layer. Sample deformation continues in all layers upon the reflection of the stress waves from the distal end of the sample. In cases where the lowest density layer is oriented towards the impact face, a completely different deformation response is observed. A detailed full-field analysis of strain and stress is performed. The mechanisms associated with the formation and propagation of stress waves from the impact ends to the distal ends of the samples are discussed

A case of contained jejunal perforation secondary to trichobezoar in a 65-year-old woman

Bezoars are conglomerations of undigested foreign material retained in the gastrointestinal tract. Trichobezoars consist of swallowed hair and constitute less than 6% of all bezoars. We present a case of jejunal trichobezoar with an intra-abdominal mass and contained jejunal perforation with a localized abscess in a 65-year-old female patient. She was scanned with contrast-enhanced abdominal CT. The patient underwent exploratory laparotomy with removal of the mass, abscess drainage, and jejunal resection with end-to-end anastomosis.  Trichobezoars should be considered in the differential diagnosis of an intra-abdominal mass in older patients like ours. We are reporting this case as trichobezoar is a rare condition and it is even rarer in a 65-year-old woman without an underlying risk factor. So, we hope this will create some awareness among physicians of the condition

A rare case of ileo-ileal knotting with strangulated intestinal obstruction

The ileo-ileal knot is an extremely rare surgical emergency that results in gangrene of the affected bowel segment. Only a few cases have been reported in the literature. Most of the time, it is an intraoperative diagnosis. Intestinal knot formation, specifically the ileo-ileal knot, is a comparatively uncommon aetiology of strangulated intestinal obstruction. Here we report a case of strangulated intestinal obstruction in a 45-year-old male patient secondary to ileo-ileal knotting. Emergency laparotomy, en-bloc ileal resection of 80 cm, and end-to-end ileo-ileal anastomosis were performed. On the 12th postoperative day, the patient was discharged after being treated for a superficial surgical site infection. The purpose of this case report is to remind physicians that ileo-ileal knotting should be considered in the differential diagnosis of a patient with intestinal obstruction, and that if the knot is strangulated, en-bloc resection is the primary intraoperative measure to consider in the management of these patients

The COVID-19 pandemic and healthcare systems in Africa:A scoping review of preparedness, impact and response

BACKGROUND: The COVID-19 pandemic has overwhelmed health systems in both developed and developing nations alike. Africa has one of the weakest health systems globally, but there is limited evidence on how the region is prepared for, impacted by and responded to the pandemic. METHODS: We conducted a scoping review of PubMed, Scopus, CINAHL to search peer-reviewed articles and Google, Google Scholar and preprint sites for grey literature. The scoping review captured studies on either preparedness or impacts or responses associated with COVID-19 or covering one or more of the three topics and guided by Arksey and O’Malley’s methodological framework. The extracted information was documented following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension checklist for scoping reviews. Finally, the resulting data were thematically analysed. RESULTS: Twenty-two eligible studies, of which 6 reported on health system preparedness, 19 described the impacts of COVID-19 on access to general and essential health services and 7 focused on responses taken by the healthcare systems were included. The main setbacks in health system preparation included lack of available health services needed for the pandemic, inadequate resources and equipment, and limited testing ability and surge capacity for COVID-19. Reduced flow of patients and missing scheduled appointments were among the most common impacts of the COVID-19 pandemic. Health system responses identified in this review included the availability of telephone consultations, re-purposing of available services and establishment of isolation centres, and provisions of COVID-19 guidelines in some settings. CONCLUSIONS: The health systems in Africa were inadequately prepared for the pandemic, and its impact was substantial. Responses were slow and did not match the magnitude of the problem. Interventions that will improve and strengthen health system resilience and financing through local, national and global engagement should be prioritised

The COVID-19 pandemic and healthcare systems in Africa : a scoping review of preparedness, impact and response

Funding Information: Funding GAT was supported with funding from the Australia National Health and Medical Research Council (NHMRC) Investigator Grant #1195716.Peer reviewedPublisher PD

Global burden of cardiovascular diseases and risk factors, 1990-2019 : Update from the GBD 2019 Study

Cardiovascular diseases (CVDs), principally ischemic heart disease (IHD) and stroke, are the leading cause of global mortality and a major contributor to disability. This paper reviews the magnitude of total CVD burden, including 13 underlying causes of cardiovascular death and 9 related risk factors, using estimates from the Global Burden of Disease (GBD) Study 2019. GBD, an ongoing multinational collaboration to provide comparable and consistent estimates of population health over time, used all available population-level data sources on incidence, prevalence, case fatality, mortality, and health risks to produce estimates for 204 countries and territories from 1990 to 2019. Prevalent cases of total CVD nearly doubled from 271 million (95% uncertainty interval [UI]: 257 to 285 million) in 1990 to 523 million (95% UI: 497 to 550 million) in 2019, and the number of CVD deaths steadily increased from 12.1 million (95% UI:11.4 to 12.6 million) in 1990, reaching 18.6 million (95% UI: 17.1 to 19.7 million) in 2019. The global trends for disability-adjusted life years (DALYs) and years of life lost also increased significantly, and years lived with disability doubled from 17.7 million (95% UI: 12.9 to 22.5 million) to 34.4 million (95% UI:24.9 to 43.6 million) over that period. The total number of DALYs due to IHD has risen steadily since 1990, reaching 182 million (95% UI: 170 to 194 million) DALYs, 9.14 million (95% UI: 8.40 to 9.74 million) deaths in the year 2019, and 197 million (95% UI: 178 to 220 million) prevalent cases of IHD in 2019. The total number of DALYs due to stroke has risen steadily since 1990, reaching 143 million (95% UI: 133 to 153 million) DALYs, 6.55 million (95% UI: 6.00 to 7.02 million) deaths in the year 2019, and 101 million (95% UI: 93.2 to 111 million) prevalent cases of stroke in 2019. Cardiovascular diseases remain the leading cause of disease burden in the world. CVD burden continues its decades-long rise for almost all countries outside high-income countries, and alarmingly, the age-standardized rate of CVD has begun to rise in some locations where it was previously declining in high-income countries. There is an urgent need to focus on implementing existing cost-effective policies and interventions if the world is to meet the targets for Sustainable Development Goal 3 and achieve a 30% reduction in premature mortality due to noncommunicable diseases

On the Failure and Fracture of Polymer Foam Containing Discontinuities

An experimental study is performed to investigate the tensile failure and fracture behavior of polymer foam containing discontinuities. PVC corecell foam, series A800 and A1200 is used for the investigation. Unnotched dog-bone specimen and specimens with center hole and edge cracks are tested under uniaxial tensile loading. Series of experiments are conducted at different defect size to width ratios, and the effect of the defect size on the net-section tensile strength of the foam is investigated. A fracture study is also conducted, and the effect of density and loading rate on the fracture behavior of foam is investigated. A minimal notch-strengthening effect is observed in specimens with center hole, and a notch-weakening effect is observed in specimen with edge notches. Furthermore, the fracture toughness increases with the increase in the foam density and decreases with the increase in loading rate.</jats:p