A multi-scale model that combines the finite element method and stochastic analysis is developed to simulate the evolution of the microstructure of an Nb-bearing nickel-based superalloy during laser ...additive manufacturing solidification. Through the use of this model, the nucleation and growth of dendrites, the segregation of niobium (Nb) and the formation of Laves phase particles during the solidification are investigated to provide the relationship between the solidification conditions and the resultant microstructure, especially in the morphology of Laves phase particles. The study shows that small equiaxed dendrite arm spacing under a high cooling rate and low temperature gradient to growth rate (G/R) ratio is beneficial for forming discrete Laves phase particles. In contrast, large columnar dendrite arm spacing under a low cooling rate and high G/R ratio tends to produce continuously distributed coarse Laves phase particles, which are known to be detrimental to mechanical properties. In addition, the improvement of hot cracking resistance by controlling the morphology of Laves phase particles is discussed by analyzing the cracking pattern and microstructure in the laser deposited material. This work provides valuable understanding of solidification microstructure development in Nb-bearing nickel-based superalloys, like IN 718, during laser additive manufacturing and constitutes a fundamental basis for controlling the microstructure to minimize the formation of deleterious Laves phase particles.
The deleterious effects of Resident Doctors' (RDs') long duty hours are well documented. Driven by concerns over the physician's well-being and patient safety, the RDs' duty hours in many developed ...countries have been capped. However, in Nigeria and many African countries, there are no official regulations on work hours of RDs. This study evaluated the work schedule of Nigerian RDs and its impact on their wellbeing and patient safety.
A national survey of 1105 Nigerian RDs from all specialties in 59 training institutions was conducted. With an electronic questionnaire designed using Google Forms, data on the work activities of RDs were obtained and analyzed using the IBM SPSS software version 24. The associations were compared using Chi-squared test with the level of significance set at < 0.05.
The mean weekly duty hours (h) of the RDs was 106.5 ± 50.4. Surgical residents worked significantly longer hours than non-surgical residents (122.7 ± 34.2 h vs 100.0 ± 43.9 h;
< 0.001). The modal on-call frequency was two weekday on-calls per week (474, 42.9%) and two weekend on-calls per month (495, 44.8%), with the majority of RDs working continuously for up to 24 hours during weekday on-calls (854, 77.3%) and 48-72 hours during weekend on-calls (568, 51.4%), sleeping for an average of only four hours during these on-calls. The majority of RDs had post-call clinical responsibilities (975, 88.2%) and desired official regulation of duty hours (1,031, 93.3%).
The duty hours of Nigerian RDs are currently long and unregulated. There is an urgent need to regulate them for patient and physician safety.
The presence of emerging micropollutants such as pharmaceuticals, endocrine disruptors, personal care products, nanomaterials and perfluorinated substances in the environment remains a great threat ...to the health and safety of humans and aquatic species. These micropollutants enter the environment via anthropogenic activities and have been detected in surface water, groundwater and even drinking water at nanogram per litre to microgram per litre concentration. To date, limited information exists on the fate, behaviours, and pathways of these micropollutants in the environment. The potential ecotoxicological effects on the receptors due to exposure to individual or mixture of these chemicals still remain unknown. This review provides an overview on pharmaceuticals, endocrine disrupting compounds, personal care products, nanomaterials and perfluorinated pollutants, with emphasis on their occurrences, effects, environmental fates, and potential risk of exposure in water, soil or sediment. Based on the literature survey, it was found that in spite of an extensive research and different developmental efforts on the challenges of emerging micropollutants, the solution to the problem of emerging micropollutants in the environment is far from being solved. The needs for behavioural change among citizens, strong political will and policy formulation on the part of government are identified as possible panacea for combating the growing influence of these potential damaging substances. Suggestions on proactive and precautionary measures that must be taken to protect the environment as well as guarantee the health and safety of humans and aquatic species are provided. Future research should concentrate on the development of a risk based screening models and framework that can predict the sources, fate and behaviours of emerging contaminants in the environment is recommended.
The study was carried out to determine the chemical composition of composite pellets of
Megathyrsus maximus
containing
Leucaena leucocephala
seed meal at the varying level and growth responses, as ...well as haematological and serum biochemical of rabbits, fed the pellets for 60 days. The treatment consists of
M. maximus
and
L. leucocephala
—100:0, 90:10, 80:20, 70:30 and 60:40, respectively. Results revealed an increase (
P
< 0.05) in the proximate composition of the grass pellets with an increase in seed inclusion while there was a reduction (
P
< 0.05) in the NDF contents of the pellets. An increase in the tannin contents was recorded with an increase in seed inclusion to the grass pellets. Rabbits fed with 30 and 40% inclusions of seed in the grass pellets had similar weight gain while the lowest feed conversion ratio was recorded in rabbits fed grass with 30% seed inclusion. Packed cell volume, RBC and lymphocyte in rabbits were altered with feeding grass seed pellet (
P
< 0.05), although no particular pattern was followed. Total protein, globulin and urea contents were reduced in the rabbits as the contents of the seeds in the grass pellets increased. Albumin contents in pellets with 30% of seeds were higher in the rabbits fed the pellets above other treatments. It can be concluded that increasing the seed meal level up to 30% in grass pellets supported growth response without inflicting any side effects on the health indices of the rabbits.
We report the results of a phase IIB study investigating the safety and effectiveness of atorvastatin use with standard anti-TB drugs.
In this multicentre, open-labelled study, we recruited ...treatment-naÏve patients with uncomplicated pulmonary TB aged at least 18 years. Participants were randomly assigned to standard-of-care or standard-of-care plus oral dose of atorvastatin (40 mg) daily for 2 months. Primary end points were safety measured by the number of participants with severe adverse events and effectiveness measured by the number of participants with negative sputum culture. Secondary endpoint was chest X-ray (CXR) severity score.
Of the 185 participants screened, 150 were enrolled and equally assigned to the standard-of-care and atorvastatin groups. Adverse event severity was similar in the two groups. There was increased frequency of muscle pain in the trial group (12/75, 16% vs. 4/75, 5%). For efficacy analysis, respectively 64 (97%) and 57 (85.1%) patients in the trial and control groups had culture-negative results (
= 0.02) and experienced a reduction in CXR severity score of respectively 37% and 22%, with a mean difference of 1.4-4.9%.
Atorvastatin is safe and associated with improved microbiological and radiological outcomes in TB.
Background: Pregnancy is a physiological process associated with an increased hemodynamic load and cardiac structural remodeling. Limited echocardiographic information exists on cardiac chambers, ...left ventricular (LV) systolic and diastolic functions, and LV mass during trimesters of normal pregnancy among African women. Materials and methods: Echocardiography was done at the beginning of the second trimester, beginning of the third trimester, and middle of the third trimester for 100 normal pregnant women and at one visit for age-matched 100 non-pregnant women. The data were analyzed using the Statistical Package for Social Sciences (SPSS) version 17 software. Analysis of variance was used to compare within trimesters, and a P value of ＜0.05 was considered significant. Results: The mean (SD) ages of the patients and controls were 28.20 (±5.91) and 28.35 (±6.06) years, respectively (age range = 19-44 years, P = 0.86). Cardiac chambers, LV systolic function, and LV mass and its index increased significantly during pregnancy. A significant increase in A-wave velocity but slight increase in E-wave velocity and a reduction in tissue e' velocity at the septal margin but a progressive increase in a' velocity were also observed (P＜0.05). Conclusion: Cardiac chamber dimensions, LV wall thickness, and mass, most indices of LV systolic and diastolic function, though within normal range, were significantly higher in pregnant than in nonpregnant Nigerian women.
Controlled environment agriculture (CEA) is an unconventional production system that is resource efficient, uses less space, and produces higher yields. Deep learning (DL) has recently been ...introduced in CEA for different applications including crop monitoring, detecting biotic and abiotic stresses, irrigation, microclimate prediction, energy efficient controls, and crop growth prediction. However, no review study assess DL’s state of the art to solve diverse problems in CEA. To fill this gap, we systematically reviewed DL methods applied to CEA. The review framework was established by following a series of inclusion and exclusion criteria. After extensive screening, we reviewed a total of 72 studies to extract the useful information. The key contributions of this article are the following: an overview of DL applications in different CEA facilities, including greenhouse, plant factory, and vertical farm, is presented. We found that majority of the studies are focused on DL applications in greenhouses (82%), with the primary application as yield estimation (31%) and growth monitoring (21%). We also analyzed commonly used DL models, evaluation parameters, and optimizers in CEA production. From the analysis, we found that convolutional neural network (CNN) is the most widely used DL model (79%), Adaptive Moment Estimation (Adam) is the widely used optimizer (53%), and accuracy is the widely used evaluation parameter (21%). Interestingly, all studies focused on DL for the microclimate of CEA used RMSE as a model evaluation parameter. In the end, we also discussed the current challenges and future research directions in this domain.
Water pollution through natural and anthropogenic activities has become a global problem causing short-and long-term impact on human and ecosystems. Substantial quantity of individual or mixtures of ...organic pollutants enter the surface water via point and nonpoint sources and thus affect the quality of freshwater. These pollutants are known to be toxic and difficult to remove by mere biological treatment. To date, most researches on the removal of organic pollutants from wastewater were based on the exploitation of individual treatment process. This single-treatment technology has inherent challenges and shortcomings with respect to efficiency and economics. Thus, application of two advanced treatment technologies characterized with high efficiency with respect to removal of primary and disinfection by-products in wastewater is desirable. This review article focuses on the application of integrated technologies such as electrohydraulic discharge with heterogeneous photocatalysts or sonophotocatalysis to remove target pollutants. The information gathered from more than 100 published articles, mostly laboratories studies, shows that process integration effectively remove and degrade recalcitrant toxic contaminants in wastewater better than single-technology processing. This review recommends an improvement on this technology (integrated electrohydraulic discharge with heterogeneous photocatalysts) viz-a-vis cost reduction in order to make it accessible and available in the rural and semi-urban settlement. Further recommendation includes development of an economic model to establish the cost implications of the combined technology. Proper monitoring, enforcement of the existing environmental regulations, and upgrading of current wastewater treatment plants with additional treatment steps such as photocatalysis and ozonation will greatly assist in the removal of environmental toxicants.
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