Axial fatigue of a gas-nitrided quenched and tempered AISI 4140 steel: effect of nitriding depth

International audienceFatigue failure of a gas-nitrided 4140 steel under axial cyclic loading results from a competition between surface crack initiation in the nitrided case and internal "fish-eye" cracking inside the core material. When nitriding is deep enough, the internal mechanism prevails in smooth specimens and fatigue strength improvement as compared to base metal is about 20%. In the present study, three V-notched specimens (blunt-medium-severe) are designed to be representative of the stress gradient (i) in a small rotary bending specimen, (ii) at the root of a gear tooth, and (iii) at the root of a very sharp notch. The cracking mechanism depends on the notch severity. The nitrided blunt notch fails from a fish-eye nucleated at the case/core boundary whereas the medium and sharp notches fail from surface cracks. The high-cycle fatigue strength improvement varies from 80% for the blunt notch and to more than 100% for the sharp notch. The notch fatigue behaviour of nitrided steel is discussed by comparing the evolutions of internal and surface fatigue strengths with relative stress gradient

Diagnosis of crop secondary and micro-nutrient deficiencies in sub-Saharan Africa

Published online: 10 Jan 2019Crop production in sub-Saharan Africa has numerous biotic and abiotic constraints, including nutrient deficiencies. Information on crop response to macronutrients is relatively abundant compared with secondary and micronutrients (SMN). Data from 1339 trial replicates of 280 field trials conducted from 2013 to 2016 in 11 countries were analyzed for the diagnosis of SMN deficiencies. The diagnostic data included relative yield response (RYR) and soil and foliar test results. The RYR to application of a combination of Mg, S, Zn, and B (Mg–S–Zn–B) relative to a comparable N–P–K treatment was a > 5% increase for 35% of the legume blocks and 60% of the non-legume blocks. The frequencies of soil test Zn, Cu, and B being below their critical level were 28, 2 and 10% for eastern and southern Africa, respectively, and 55, 58 and 89% for western Africa, while low levels for other SMN were less frequent. The frequency of foliar results indicating low availability were 58% for Zn, 16% for S and less for other SMN. The r2 values for relationships between soil test, foliar test and RYR results were < 0.035 with little complementarity except for soil test Zn and B with cassava (Manihot esculenta L. Crantz) RYR in Ghana, and foliar Zn with cereal RYR in Uganda. Positive RYR is powerful diagnostic information and indicative of good profit potential for well-targeted and well-specified SMN application. Geo-referenced RYR, soil analysis and foliar analysis results for diagnosis of SMN deficiencies in 11 countries of sub-Saharan Africa were generally not complementary

The Impact of Dietary Consumption of Palm Oil and Olive Oil on Lipid Profile and Hepatocyte Injury in Hypercholesterolemic Rats

A metabolic disease called hypercholesterolemia is connected to both oxidative damage and inflammation. The goal of the current investigation was to determine if olive oil and palm oil could prevent hypercholesterolemia-induced oxidative stress in the liver of rats fed a high-cholesterol diet (HCD). The experimental mice were given HCD for three months while also receiving 0.5 mL/kg of either palm or olive oil. Serum triglycerides, total cholesterol, LDL cholesterol, vLDL cholesterol, and the atherogenic index all significantly increased in HCD-fed rats, while HDL cholesterol significantly dropped. Additionally, HCD caused a notable rise in proinflammatory cytokines and serum transaminases in liver tissue. Additionally, HCD significantly increased the production of nitric oxide and lipid peroxidation in the liver while decreasing antioxidant enzymes. Treatment with palm and olive oils dramatically reduced the levels of pro-inflammatory cytokines and lipid peroxidation, improved antioxidant defenses, and considerably improved liver function indicators. Additionally, the examined oils dramatically decreased the expression of fatty acid synthase (FAS) in the liver of rats receiving HCD. In conclusion, HCD-fed rats exhibit significant antihyperlipidemic and cholesterol-lowering benefits from palm and olive oils. The improved antioxidant defenses, lower inflammation and lipid peroxidation, and altered hepatic FAS mRNA expression were the main mechanisms by which palm and olive oils produced their advantageous effects

A novel mechanism for variable phenotypic expressivity in Mendelian diseases uncovered by an AU-rich element (ARE)-creating mutation

Abstract Background Variable expressivity is a well-known phenomenon in which patients with mutations in one gene display varying degrees of clinical severity, potentially displaying only subsets of the clinical manifestations associated with the multisystem disorder linked to the gene. This remains an incompletely understood phenomenon with proposed mechanisms ranging from allele-specific to stochastic. Results We report three consanguineous families in which an isolated ocular phenotype is linked to a novel 3′ UTR mutation in SLC4A4, a gene known to be mutated in a syndromic form of intellectual disability with renal and ocular involvement. Although SLC4A4 is normally devoid of AU-rich elements (AREs), a 3′ UTR motif that mediates post-transcriptional control of a subset of genes, the mutation we describe creates a functional ARE. We observe a marked reduction in the transcript level of SLC4A4 in patient cells. Experimental confirmation of the ARE-creating mutation is shown using a post-transcriptional reporter system that reveals consistent reduction in the mRNA-half life and reporter activity. Moreover, the neo-ARE binds and responds to the zinc finger protein ZFP36/TTP, an ARE-mRNA decay-promoting protein. Conclusions This novel mutational mechanism for a Mendelian disease expands the potential mechanisms that underlie variable phenotypic expressivity in humans to also include 3′ UTR mutations with tissue-specific pathology

Data from: Maize-nutrient response information applied across Sub-Saharan Africa

The profit potential for a given investment in fertilizer use can be estimated using representative crop nutrient response functions. Where response data is scarce, determination of representative response functions can be strengthened by using results from homologous crop growing conditions. Maize (Zea mays L.) nutrient response functions were selected from the Optimization of Fertilizer Recommendations in Africa (OFRA) database of 5500 georeferenced response functions determined from field research conducted in Sub-Saharan Africa. Three methods for defining inference domains for selection of response functions were compared. Use of the OFRA Inference Tool (OFRA-IT; http://agronomy.unl.edu/OFRA) resulted in greater specificity of maize N, P, and K response functions with higher R2 values indicating superiority compared with using the Harvest Choice Agroecological Zones (HC-AEZ) and the recommendation domains of the Global Yield Gap Atlas project (GYGA-RD). The OFRA-IT queries three soil properties in addition to climate-related properties while the latter two options use climate properties only. The OFRA-IT was generally insensitive to changes in criteria ranges of 20–25% used in queries suggesting value in using wider criteria ranges compared with the default for information scarce crop nutrient response functions

Yield-limiting macronutrients for rice in sub-Saharan Africa.

Nutrient deficiencies are considered major constraints to rice production in sub-Saharan Africa (SSA), but a systematic, continent-wide analysis of these constraints is lacking. The objective of this study was to assess responses of rice yields to macronutrients (N, P, and K) across major rice production systems [irrigated lowland rice (IL), rainfed lowland rice (RL), and rainfed upland rice (RU)] and diverse agro-ecological zones (semi-arid, sub-humid, humid, and highlands) in SSA. Diagnostic trials were conducted in 17 countries in 18–60 farmers' fields in each of 30 sites (totaling 1037 farmers' fields), of which 12 sites were in IL, 15 in RL and 3 in RU. All trials had an NPK treatment, and three treatments in which either nitrogen (N), phosphorus (P), or potassium (K) was omitted from the NPK treatment (minus N, P, and K plots). The trials were conducted during one or two seasons. Regression between yields in the NPK and minus N plots was used for calculating N fertilizer requirement, following the approach used for the development of a nutrient management decision support tool for rice (RiceAdvice) in SSA. Site mean yields in the NPK treatment ranged from 1.4 to 7.3 t ha−1. On average, these yields were 1.1 t ha−1 higher than farmers' yields previously observed in the same sites. N was generally the most limiting nutrient, followed by P. Rice yields without N, P, and K were 68, 84, and 89% of yields in the NPK treatment, and were positively correlated with those in the NPK treatment irrespective of production systems and agro-ecological zone (AEZ). Results from a regression model across sites indicated that achieving 3, 5, and 7 t ha−1 requires N fertilizer application at an average rate of 56, 91, and 122 kg N ha−1, respectively. However, there was significant treatment by site interaction on rice yield. Site mean yields were significantly lower without N, P, and K in 93, 60, and 50% of sites as compared to the NPK treatment. Yield response to macronutrients varied across sites and was not related to production system, nor AEZ. Results from this study will help further improvement of RiceAdvice for providing decision support tailored to the particular site, zone, or production system, thereby closing yield gaps, improving fertilizer nutrient efficiency and preventing negative environmental consequences of fertilizer use

Antidiabetic, Antioxidant and Antihyperlipidemic Status of Heliotropium zeylanicum Extract on Streptozotocin-Induced Diabetes in Rats

The potential role of the methanolic extract of Heliotropium zeylanicum (BURM.F) LAMK (MEHZ) in the treatment of diabetes along with its antioxidant and antihyperlipidemic effects was studied in streptozotocin-induced diabetic rats. Oral administration of (MEHZ) 150 and 300 mg/kg/d for 14 d significantly decreased the blood glucose level and considerably increased the body weight, food intake, and liquid intake of diabetic-induced rats. MEHZ significantly decreased thiobarbituric acid reactive substances and significantly increased reduced glutathione, superoxide dismutase and catalase in streptozotocin-induced diabetic rats at the end of 14 d of treatment. The study also investigated the antihyperlipidemic potential of MEHZ. The results show that the active fraction of MEHZ is promising for development of a standardized phytomedicine for the treatment of diabetes mellitus