This study used Finite Element (FE) modelling to investigate how CIC application changes the expected fatigue initiation behaviour in 1.5 single-shear lap joint samples. The FE models included the Hi-Lok interference fit and clamping force, as well as the frictional differences with and without CIC application. Results from the modelling were processed via various fatigue equivalent cyclic stress or strain methods to estimate the crack initiation location, or "hotspot", and whether there was likely to be a change in the initiation duration with CIC application. The experimental results showed an eyebrow fretting damage zone above fastener the holes where the majority of fatigue cracks originated (for both the with and without CIC cases). The FE modelling demonstrated that many of the considered hotspot methods were able to correctly predict the eyebrow stress concentration zone. However, not all methods were able to predict whether the initiation duration was likely to increase or decrease with application of CICs. The best method was a fretting based parameter, which correctly predicted the increase in life with CIC application. Overall, this study highlights which fatigue equivalent cyclic stress/strain methods are suitable to account for the effects of CIC application in lap joints.

Characterization of the crack tip, such as the stress intensity factor (SIF), is a vital step for the assessment of fatigue crack growth and prediction of potential failure in engineering structures. This study investigates the use of thermoelastic stress analysis (TSA) for SIF evaluation, including a methodology for non-adiabatic stress field correction to overcome limitations that occur due to heat conduction. Finite element modeling is used to demonstrate the limits of the underlying mathematical procedure for Mode I and Mode II loading, including the effects of crack tip plasticity, loading frequency, and material thickness. Experimental validation is undertaken through fatigue crack growth experiments using modified disk-shaped compact tension samples. The TSA based SIF evaluation technique with non-adiabatic correction enables robust experimental validation of reference SIF solutions and finite element modeling, as well as a means for direct measurement in cases where theory solutions are not available.

Corrosion-inhibiting compounds (CICs) are a secondary protection method used with aircraft that can reduce the rate of corrosion development. However, CICs can also affect the fatigue life of fastened lap joints. This study uses a 1.5 single-shear lap joint design to investigate fatigue life changes with CIC application. Hi-Lok and rivet fastener types are compared, along with the inclusion of faying surface sealant. It was found that without sealant, the application of CICs increased the fatigue life due to prolonging the crack initiation process. The presence of faying surface sealant led to a reduction in fatigue life for the rivet samples. The Hi-Lok samples saw no change in life due to the squeeze-out of the sealant around the fastener holes. This study provides a foundational understanding of the mechanisms and significance of the change in fatigue life with the presence of CICs and faying surface sealant in a fastened lap joint.

The early detection of sickle cell disease (SCD) is vital to reduce mortality among affected children. Suriname currently lacks a newborn screening programme (NSP) for SCD. We performed a pilot programme to evaluate the scalability of such an initiative. Dried blood spots were collected from five birth centres and subjected to electrophoresis analysis. The programme scalability was evaluated using the non-adoption, abandonment, scale-up, spread, and sustainability framework. Challenges across six domains (illness, technology, value proposition, adopter system, organisation, and societal system), were categorised hierarchically as simple 😊, complicated 😐, or complex 😢. It has been proven that implementing programmes with mainly complicated challenges is difficult and those in mainly complex areas may be unachievable. SCD was detected in 33 of 5185 (0.64%) successfully screened newborns. Most of the domains were classified as simple or complicated. Disease detection and technology suitability for screening in Suriname were confirmed, with favourable parental acceptance. Only minor routine adjustment was required from the medical staff for programme implementation. Complex challenges included a reliance on external suppliers for technical maintenance, ensuring timely access to specialised paediatric care for affected newborns, and securing sustainable financial funding. Scaling up is challenging but feasible, particularly with a targeted focus on identified complex challenges.

This paper presents an experimental study that investigates the deformation of a composite propeller blade subjected to a uniform inflow. An array of fiber Bragg grating sensors were embedded inside the blade, allowing for real-time monitoring of strain. Measurements were carried out in the towing tank at Centrale Nantes, France. An original experimental setup was developed to support and fully submerge the blade in the hydrodynamic facility, which reduced the effect of the free surface during testing. The blade, with a root chord of 0.3 m and a span of 0.5 m, was instrumented with embedded fiber Bragg grating (FBG) sensors on both the pressure and suction sides to measure the deformation field. The FBG measurements were dynamically synchronized with a six degree-of-freedom hydrodynamic balance to measure the loads and moments on the blade. Visualizations of the boundary layer regime were observed to determine the flow detachment regions at the surface. The carriage velocities utilized were between 1 and 4m/s and the angle of attack of the blade, based on the zero-lift angle of attack, ranged between 0 to 12∘. After determining the natural frequencies and modes of the blade using laser doppler vibrometry, the forces and deformations were investigated under hydrodynamic flow for both averaged and unsteady data. For averaged results, a good correlation is observed between the lift force and deformations, which demonstrates the accuracy of the measurement system. The fluid–structure interaction dynamic is analyzed using the frequency spectra of drag, lift, pitching moment, and deformations. The interaction between Strouhal frequencies of vortex shedding resulting from flow detachments at the blade surface is identified with the flow visualization, and the modal response of the blade is demonstrated.

A novel method of determining the crack tip location from a thermoelastic quadrature signal is presented. The method is utilised for crack tip locations within complex stress fields, namely within fastened aircraft lap joints. Coupled structural-thermal finite element modelling was undertaken to investigate the thermal response field around the crack tip location and develop the algorithmic principles. Experimental validation of the crack tip location was conducted using established crack mouth compliance techniques and optical measurements. The crack tip finding algorithm used the location of the maximum spatial gradient of the thermal field in the direction of crack growth. The method showed good accuracy when compared to traditional methods. Resultant crack growth rates were further verified using quantitative fractography.

Prenatal exposure to pesticides and the association with adverse health outcomes have been examined in several studies. However, the characterization of pesticide exposure among Surinamese women during pregnancy has not been assessed. As part of the Caribbean Consortium of Research in Environmental and Occupational Health research program, 214 urine samples were collected from pregnant women living in three regions in Suriname with different agricultural practices: capital Paramaribo, the rice producing district Nickerie, and the tropical rainforest, the Interior. We used isotope dilution tandem mass spectrometry to quantify urinary concentrations of biomarkers of three pesticide classes, including phenoxy acid herbicides and organophosphate and pyrethroid insecticides, all of which are commonly used in agricultural and residential settings in Suriname. We observed that participants residing in Nickerie had the highest urinary metabolite concentrations of 2,4-dichlorophenoxyacetic acid and pyrethroids compared to those from Paramaribo or the Interior. Paramaribo had the highest concentrations of organophosphate metabolites, specifically dialkyl phosphate metabolites. Para-nitrophenol was detected in samples from Paramaribo and the Interior. Samples from Nickerie had higher median urinary pesticide concentrations of 2,4-dichlorophenoxyacetic acid (1.06 μg/L), and the following metabolites, 3,5,6-trichloro-2-pyridinol (1.26 μg/L), 2-isopropyl-4-methyl-6-hydroxypyrimidine (0.60 μg/L), and 3-phenoxybenzoic acid (1.34 μg/L), possibly due to residential use and heavy rice production.

Epidemiological data on hepatitis B virus (HBV) are needed to benchmark HBV elimination goals. We recently assessed prevalence of HBV infection and determinants in participants attending the Emergency Department in Paramaribo, Suriname, South America. Overall, 24.5% (95%CI = 22.7-26.4%) of participants had anti-Hepatitis B core antibodies, which was associated with older age (per year, adjusted Odds Ratio [aOR] = 1.03, 95%CI = 1.02-1.04), Afro-Surinamese (aOR = 1.84, 95%CI = 1.52-2.19) and Javanese ethnicity (aOR = 1.63, 95%CI = 1.28-2.07, compared to the grand mean). 3.2% of participants were Hepatitis B surface Ag-positive, which was also associated with older age (per year, aOR = 1.02, 95%CI = 1.00-1.04), Javanese (aOR = 4.3, 95%CI = 2.66-6.95) and Afro-Surinamese ethnicity (aOR = 2.36, 95%CI = 1.51-3.71). Sex, nosocomial or culturally-related HBV transmission risk-factors were not associated with infection. Phylogenetic analysis revealed strong ethnic clustering: Indonesian subgenotype HBV/B3 among Javanese and African subgenotypes HBV/A1, HBV/QS-A3 and HBV/E among Afro-Surinamese. Testing for HBV during adulthood should be considered for individuals living in Suriname, specifically with Javanese and Afro-Surinamese ancestry.

Purpose The Caribbean Consortium for Research in Environmental and Occupational Health prospective environmental epidemiologic cohort study addresses the impact of chemical and non-chemical environmental exposures on mother/child dyads in Suriname. The study determines associations between levels of environmental elements and toxicants in pregnant women, and birth outcomes and neurodevelopment in their children. Participants Pregnant women (N=1143) were enrolled from December 2016 to July 2019 from three regions of Suriname: Paramaribo (N=738), Nickerie (N=204) and the tropical rainforest interior (N=201). Infants (N=992) were enrolled at birth. Follow-up will take place until children are 48 months old. Findings to date Biospecimens and questionnaire data on physiological and psychosocial health in pregnant women have been analysed. 39.1% had hair mercury (Hg) levels exceeding values considered safe by international standards. Median hair Hg concentrations in women from Paramaribo (N=522) were 0.64 µg/g hair (IQRs 0.36–1.09; range 0.00–7.12), from Nickerie (N=176) 0.73 µg/g (IQR 0.45–1.05; range 0.00–5.79) and the interior (N=178) 3.48 µg/g (IQR 1.92–7.39; range 0.38–18.20). 96.1% of women ate fish, respective consumption of the three most consumed carnivorous species, Hoplias aimara, Serrasalmus rhombeus and Cichla ocellaris, known to have high Hg levels, was 44.4%, 19.3% and 26.3%, respectively, and was greater among the interior subcohort. 89% frequently consumed the vegetable tannia, samples of which showed presence of worldwide banned pesticides. 24.9% of pregnant women had Edinburgh Depression Scale scores indicative of probable depression. Future plans Fish consumption advisories are in development, especially relevant to interior women for whom fish consumption is likely to be the primary source of Hg exposure. Effects of potentially beneficial neuroprotective factors in fish that may counter neurotoxic effects of Hg are being examined. A pesticide literacy assessment in pregnant women is in progress. Neurodevelopmental assessments and telomere length measurements of the children to evaluate long-term effects of prenatal exposures to toxicant mixtures are ongoing.

With the rapid pace and scale of the emerging coronavirus 2019 (COVID-19) pandemic, a growing body of evidence has shown a strong association of COVID-19 with pre- and post- neurological complications. This has necessitated the need to incorporate targeted neurological care for this subgroup of patients which warrants further reorganization of services, healthcare workforce, and ongoing management of chronic neurological cases. The social distancing and the shutdown imposed by several nations in the midst of COVID-19 have severely impacted the ongoing care, access and support of patients with chronic neurological conditions such as Multiple Sclerosis, Epilepsy, Neuromuscular Disorders, Migraine, Dementia, and Parkinson disease. There is a pressing need for governing bodies including national and international professional associations, health ministries and health institutions to harmonize policies, guidelines, and recommendations relating to the management of chronic neurological conditions. These harmonized guidelines should ensure patient continuity across the spectrum of hospital and community care including the well-being, safety, and mental health of the patients, their care partners and the health professionals involved. This article provides an in-depth analysis of the impact of COVID-19 on chronic neurological conditions and specific recommendations to minimize the potential harm to those at high risk.

The use of fiber-reinforced polymer composites in marine propellers has recently been extensively investigated, as these materials provide excellent strengthand stiffness-toweight ratios, improved fatigue performance, and reductions in corrosion, noise generation, and magnetic signature. Another advantage of composites is their increased mechanical flexibility relative to metals and thus their capacity to deform based on flow conditions, rotational velocity, and laminate design. Despite their advantages, however, advanced composite propellers are complex and their behavior is difficult to characterize. In order to fully optimize the performance and control of these blades, a detailed understanding of the dynamic coupling between the hydroelastic response of a composite blade and the surrounding flow under a wide variety of operating conditions is required. This work will present a numerical, fully-coupled fluidstructure interaction (FSI) study of a single composite propeller blade. The simulations are carried out using the Fine/Marine computational fluid dynamics solver to predict the flow behavior, which is coupled with a modal approach to capture structural deformations. Both static and dynamic coupling are tested, and the full hydrodynamic response is anayzed; experiments in a towing tank will follow. This paper aims to fully characterize the experimental setup and measurement system and to present the expected findings. Then, the combined experimental and numerical method will be used to validate an efficient FSI coupling method able to capture dynamic response of the composite blade submitted to unsteady flow conditions.

INTRODUCTION:Since the identification of ZIKV in Brazil in May 2015, the virus has spread extensively throughout the Americas. Cases of ZIKV infection have been reported in Suriname since October 2, 2015. METHODS:A laboratory-based surveillance system was quickly implemented according to previous experience with the emergence of chikungunya. General practitioners and public health centers located in different districts of Suriname were asked to send blood samples from suspicious cases to Academic Hospital for molecular diagnosis of Zika virus infection. We investigated Zika-related laboratory data collected during surveillance and response activities to provide the first outbreak report in Suriname in terms of time, location and person. RESULTS:A total of 791 molecularly confirmed cases were reported during a 48-week interval from October 2015 to August 2016. The majority of ZIKV-positive cases involved women between 20 and 39 years of age, reflecting concern about Zika infection during pregnancy. The outbreak peaked in mid-January and gradually spread from the district of Paramaribo to western coastal areas. DISCUSSION:This report provides a simple and comprehensive description of the outbreak in Suriname and demonstrates the utility of laboratory data to highlight the spatiotemporal dynamics of the outbreak in that country.

This paper discusses an algorithm for the detection of crack damage in plate structures based on the governing differential equation (GDE) of in-plane displacement of a plate. A state-of-the-art 3D scanning laser Doppler vibrometer, which is able to provide very accurate measurements of a three-dimensional displacement field, was utilized to implement the algorithm. To evaluate the GDE from the measured displacements, a 2D Savitzky–Golay differentiating filter was used. The potential of this algorithm for detecting a crack was compared against another two algorithms which are based on displacement measurements. The first is an algorithm based on the error in smoothed to measured displacements and the other uses surface strains normalized by their mean. To investigate the efficiency of the algorithms in detecting crack damage, a number of PMMA plate specimens were fabricated with a range of crack lengths extending from a V-notch and tested under a cyclic, quasi-static, uni-axial load. For each algorithm, the crack location could be positively identified. However, the two algorithms based on the error in smoothed to measured displacements and surface strains normalized by their mean were found to be dependent on the direction of the applied load, whereas, theoretically the algorithm based on the GDE of in-plane displacement would work regardless of the direction of the applied load.

The mammalian target of rapamycin complex 1 (mTORC1) is activated by extracellular factors that control bone accrual. However, the direct role of this complex in osteoblast biology remains to be determined. To investigate this question, we disrupted mTORC1 function in preosteoblasts by targeted deletion of Raptor (Rptor) in Osterix-expressing cells. Deletion of Rptor resulted in reduced limb length that was associated with smaller epiphyseal growth plates in the postnatal skeleton. Rptor deletion caused a marked reduction in pre-and postnatal bone accrual, which was evident in skeletal elements derived from both intramembranous and endochondrial ossification. The decrease in bone accrual, as well as the associated increase in skeletal fragility, was due to a reduction in osteoblast function. In vitro, osteoblasts derived from knockout mice display a reduced osteogenic potential, and an assessment of bone-developmental markers in Rptor knockout osteoblasts revealed a transcriptional profile consistent with an immature osteoblast phenotype suggesting that osteoblast differentiation was stalled early in osteogenesis. Metabolic labeling and an assessment of cell size of Rptor knockout osteoblasts revealed a significant decrease in protein synthesis, a major driver of cell growth. These findings demonstrate that mTORC1 plays an important role in skeletal development by regulating mRNA translation during preosteoblast differentiation.

Objective The aim of this in vitro study was to evaluate the progressive development of surface microdamage produced following the insertion of orthodontic miniscrews (OMs) into 1.5 mm thick porcine tibia bone using maximum insertion torque values of 12 Ncm, 18 Ncm, and 24 Ncm. Methods Aarhus OMs (diameter 1.5 mm; length 6 mm) were inserted into 1.5 mm porcine bone using a torque limiting hand screwdriver set at 12 Ncm, 18 Ncm, and 24 Ncm. A custom rig equipped with a compression load cell was used to record the compression force exerted during manual insertion. A sequential staining technique was used to identify microdamage viewed under laser confocal microscopy. Virtual slices were created and stitched together to form a compressed two-dimensional composition of the microdamage. Histomorphometric parameters, including total damage area, diffuse damage area, maximum crack length, maximum damage radius, and maximum diffuse damage radius, were measured. Kruskal-Wallis Tests and Wilcoxon Rank-Sum Tests were used to analyse the generated data. Results All OMs inserted using 12 Ncm failed to insert completely, while partial insertion was observed for two OMs inserted at 18 Ncm. Complete insertion was achieved for all OMs inserted at 24 Ncm. Histomorphometrically, OMs inserted using 24 Ncm produced a significantly larger diffuse damage area (P < 0.05; P < 0.05) and maximum diffuse damage radius (P < 0.05; P < 0.05), for both the entry and exit surfaces, respectively, compared with the 12 Ncm and 18 Ncm groups. Conclusions Insertion torque can influence the degree of OM insertion and, subsequently, the amount of microdamage formed following insertion into 1.5 mm thick porcine tibia bone. An increase in insertion torque corresponds with greater insertion depth and larger amounts of microdamage.

Introduction: The aim of this in-vitro study was to investigate the influence of cortical bone thickness on the amount of surface microdamage produced after insertion of orthodontic miniscrews (OM) in porcine tibia bone. Methods: Aarhus OMs (Medicon, Tuttlingen, Germany; diameter, 1.5 mm; length, 6 mm) were inserted into 1.0 mm (group A; n = 10), 1.5 mm (group B; n = 10), and 2.0 mm (group C; n = 10) of porcine cortical bone using a torque-limiting hand screwdriver set at 18 Ncm. A sequential staining technique was used to identify microdamage under laser confocal microscopy. Virtual slices were stitched together using ImageJ software (National Institutes of Health, Bethesda, Md) to form a compressed 2-dimensional composition of the microdamage. The ImageJ software was used to quantify the total damage area, diffuse damage area, maximum crack length, maximum damage radius, and maximum diffuse damage radius. Kruskal-Wallis tests and Wilcoxon rank sum tests were used to analyze the data. Results: All OMs in group A (1.0 mm) were inserted completely; however, 2 OMs from group B (1.5 mm) and all OMs in group C (2.0 mm) failed to insert completely. The entry surface of group C (2.0 mm) exhibited significantly higher amounts of total damage, diffuse damage area, maximum crack length, and maximum crack damage radius compared with groups A (1.0 mm) and B (1.5 mm). The maximum crack length observed on the entry and exit surfaces ranged from 1.03 to 3.06 mm. Conclusions: In this study, we demonstrated a higher level of microdamage after the insertion of OMs into 2.0-mm thick cortical bone compared with 1.0-mm thick cortical bone. Therefore, clinicians need to consider the thickness of the cortical bone at the insertion site, because mechanisms to reduce cortical bone thickness would likely reduce the amount of microdamage formed. A safety zone of 3.5 mm from the OM is also recommended for OMs inserted into 1.0-and 1.5-mm cortical bone thicknesses to minimize any detrimental effects after targeted remodeling.

Acute Zika virus (ZIKV) infection is usually mild and self-limiting. Earlier, we reported three cases of fatal acute ZIKV infection in patients without typical signs of ZIKV, but rather with criteria of systemic inflammation response syndrome (SIRS). To follow up these observations, we prospectively included patients at the emergency room with temperature instability and suspected to have acute ZIKV infection, SIRS, or both. A total of 102 patients were included of whom N = 21 (21%) were suspected of acute ZIKV infection, N = 56 (55%) of acute ZIKV infection with SIRS criteria, and N = 25 (24%) of SIRS alone. ZIKV-PCR was positive in N = 21 (20%) patients. Eight (38%) ZIKV-positive patients needed admission to the hospital of whom four (50%) presented with SIRS alone. One ZIKV-positive patient had vascular co-morbidity and died following shock and severe coagulopathy. We confirm the hypothesis that acute ZIKV infection can present atypical and severely with systemic inflammation and have lethal course particularly amongst patients with significant prior disease.

BACKGROUND:Flexor tendon repair failures have primarily been attributed to either core suture rupture or core suture pull out. Recent studies have suggested that knot unravelling may also cause failure of a tendon repair. The aim of this study was to investigate the causes of core suture failure in two types of common flexor tendon repairs.METHODS:Twenty four cadaver tendons were divided into three groups of eight. Each group tested a specific flexor tendon repair. The repairs tested included an Adelaide repair using 4/0 Ethibond (Ethicon), an Adelaide repair using 4/0 Fiberwire (Arthrex) and the Tsai repair with 4/0 Fiberloop (Arthrex). The repaired tendons were pull-tested to failure. The mechanism of failure, maximum tensile strength and 2 mm gap force were recorded.RESULTS:The predominant mode of failure was by the knot unravelling. This occurred in 50-88% of the tendon repairs. The sequence of failure was initiated with gapping at the repair site followed by failure of the epitendinous suture. Next the core suture knot unravels. Once the knot unravels, the suture thread slips out of the tendon resulting in the repair failure. Failures due to knot slippage occurred at a lower maximum tensile strength in Ethibond and Fiberloop sutures than failure due to core rupture or pull out. However, given the small number of tendons tested, this result was not significant.CONCLUSIONS:This study has clearly demonstrated one of the main causes of flexor tendon repair failure in two common repair techniques is knot unravelling.