Microstructure development and its control in dual-phase titanium alloy (Ti-6Al-4V) are challenging as they involve a complex processing route. Any inhomogeneity in microstructure or texture results ...in variation in the mechanical properties. Such inhomogeneity develops during the deformation step of the processing route and may persist in the final forged product. In this study, a processing route for bimodal microstructure development has been proposed to understand microstructural inhomogeneity and its effect on mechanical properties. Electron backscatter diffraction analysis suggests the formation of local microtexture (or macrozone) during the lamellar breakdown. Following the hot deformation stage, recrystallization annealing treatments were performed for different soaking time periods. A homogenous bimodal microstructure is achieved at a higher annealing time of 4 h or more. The local texture weakening at a higher annealing time is due to recrystallization. Further, fracture toughness (
K
Ic
) tests were performed on bimodal microstructure with lamellar fractions 31 and 67%, respectively, to understand the influence of morphology on the crack resistance. It was found that the bimodal microstructure with a higher lamellar fraction has weaker texture intensity and enhances fracture toughness.
Systemic lupus erythematous (SLE) is a chronic autoimmune disorder, broadly characterized by systemic inflammation along with heterogeneous clinical manifestations, severe morbidity, moribund organ ...failure and eventual mortality. In our study, SLE patients displayed a higher percentage of activated, inflamed and hyper-polarized CD8
T cells, dysregulated CD8
T cell differentiation, significantly elevated serum inflammatory cytokines and higher accumulation of cellular ROS when compared to healthy controls. Importantly, these hyper-inflammatory/hyper-polarized CD8
T cells responded better to an antioxidant than to an oxidant. Terminally differentiated Tc1 cells also showed plasticity upon oxidant/antioxidant treatment, but that was in contrast to the SLE CD8
T cell response. Our studies suggest that the differential phenotype and redox response of SLE CD8
T cells and Tc1 cells could be attributed to their cytokine environs during their respective differentiation and eventual activation environs. The polarization of Tc1 cells with IL-21 drove hyper-cytotoxicity without hyper-polarisation suggesting that the SLE inflammatory cytokine environment could drive the extreme aberrancy in SLE CD8
T cells.
A novel S
b
Salt Inducible (
-1) gene was isolated and overexpressed in tobacco for
functional validation subjected to drought and salt stress.
-1 is a nuclear protein. The transgenic tobacco ...overexpressing
-1 gene exhibited better seed germination, growth performances, pigment contents, cell viability, starch accumulation, and tolerance index under drought and salt stress. Overexpression of
-1 gene alleviated the build-up of reactive oxygen species (ROS) and curtailed the ROS-induced oxidative damages thus improved the physiological health of transgenic tobacco under stressed conditions. The higher activities of antioxidant enzymes, lower accumulation of ROS, higher membrane stability, relative water content, and polyphenol contents indicated the better survival of the transgenic tobacco than wild-type (WT) tobacco under stressed conditions. Transgenic tobacco had a higher net photosynthetic rate, PSII operating efficiency, and performance index under drought and salt stress. Higher accumulation of compatible solutes and K
/Na
ratio in transgenic tobacco than WT showed the better osmotic and redox homeostasis under stressed conditions. The up-regulation of genes encoding antioxidant enzymes (
, and
) and transcription factors (
and
) in transgenic tobacco under stressed conditions showed the role of
-1 in ROS alleviation and involvement of this gene in abiotic stress tolerance. Multivariate data analysis exhibited statistical distinction among growth responses, physiological health, osmotic adjustment, and photosynthetic responses of WT and transgenic tobacco under stressed conditions. The overexpression of
-1 gene curtailed the ROS-induced oxidative damages and maintained the osmotic homeostasis under stress conditions thus improved physiological health and photosynthetic efficiencies of the transgenic tobacco overexpressing
-1 gene.
In the era of climate change, the overall productivity of pea (
L.) is being threatened by several abiotic stresses including heat stress (HS). HS causes severe yield losses by adversely affecting ...several traits in peas. A reduction in pod yield has been reported from 11.1% to 17.5% when mean daily temperature increase from 1.4 to 2.2°C. High-temperature stress (30.5-33°C) especially during reproductive phase is known to drastically reduce both seed yield and germination. HS during germination and early vegetative stage resulted in poor emergence and stunted plant growth along with detrimental effects on physiological functions of the pea plant. To combat HS and continue its life cycle, plants use various defense strategies including heat escape, avoidance or tolerance mechanisms. Ironically, the threshold temperatures for pea plant and its responses are inconsistent and not yet clearly identified. Trait discovery through traditional breeding such as semi leaflessness (
), upright growing habit, lodging tolerance, lower canopy temperature and small seeded nature has highlighted their utility for greater adaptation under HS in pea. Screening of crop gene pool and landraces for HS tolerance in a targeted environment is a simple approach to identify HS tolerant genotypes. Thus, precise phenotyping using modern phenomics tools could lead to increased breeding efficiency. The NGS (next generation sequencing) data can be associated to find the candidate genes responsible for the HS tolerance in pea. In addition, genomic selection, genome wide association studies (GWAS) and marker assisted selection (MAS) can be used for the development of HS tolerant pea genotypes. Additionally, development of transgenics could be an alternative strategy for the development of HS tolerant pea genotypes. This review comprehensively covers the various aspects of HS tolerance mechanisms in the pea plant, screening protocols, omic advances, and future challenges for the development of HS tolerant genotypes.
Background
Plant establishment, growth, development and productivity are adversely affected by abiotic stresses that are dominant characteristics of environmentally challenged/degraded habitats ...created in the Anthropocene. Crop breeding for climate resilience properties is need of the hour to sustain the crop productivity. We report on the characterization of
Kappaphycus alvarezii
(a red seaweed) Na
+
/H
+
antiporter gene (
KaNa
+
/H
+
) for enhanced salt and osmotic stress tolerance.
Methods
The
KaNa
+
/H
+
antiporter gene was cloned and over-expressed in tobacco under the control of CaMV35S promoter. Transgenic analysis was carried out to assess the stress tolerance ability of tobacco over-expressing
KaNa
+
/H
+
antiporter gene.
Results
Over-expression of
KaNa
+
/H
+
gene improved the seed germination and seed vigor index under stress. Transgenic plants grew better and exhibited delayed leaf senescence. Improved K
+
/Na
+
, carotenoid/total chlorophyll and relative water content; lower accumulation of reactive oxygen species (ROS), MDA and Na
+
; lower electrolyte leakage; better membrane stability index and accumulation of K
+
, photosynthetic pigment, starch, sugar, free amino acid, proline and polyphenol contents indicated better physiological health of the transgenic tobacco under stress. Transgenic tobacco exhibited higher photosynthesis, photosystem II efficiency, electron transfer rate, photochemical quenching and activity of water splitting complex. Compared with control tobacco, transgenic tobacco exhibited higher expression of stress-defence genes under stress and better recovery after long-term osmotic stress.
Conclusions
Lower Na
+
cytotoxicity, lower accumulation of ROS and maintenance of the membrane integrity helped transgenic tobacco to maintain the physiological functioning under stress. Present results established
K. alvarezii
as a potential gene resource and the
KaNa
+
/H
+
antiporter gene as a potential candidate gene in molecular breeding of crops for development of the degraded land.
Low cycle fatigue (LCF) tests were carried out on mill annealed Ti-6Al-4V for 100 cycles at various strain amplitudes. The strain amplitudes were chosen such that, cyclic stress remains (i) ...completely in the elastic regime (0.006), (ii) onset of the yield point (0.008), and (iii) plastic regime (0.01). Cyclic stress softening was observed at higher strain amplitude (0.008 and 0.01), whereas no change in peak stress was observed for lower strain amplitude (0.006). Cyclic softening was observed mainly due to decrease in friction stresses with the number of cycles. The microstructural analysis using transmission electron microscope (TEM) and transmission Kikuchi diffraction (TKD) suggest the formation of slip band, hexagonal network and sub-grain boundary. The lower strain amplitude evidences the formation of slip bands and dislocation rearrangement, although the cyclic stress exhibits complete elastic behavior. In the case of higher strain amplitude, the development of defect structure and annihilation/rearrangement of dislocations occurs simultaneously. The cyclic deformation at higher strain amplitude favors the rearrangement of dislocation and formation of LABs or sub-grain boundary. The low angle boundaries appeared to originate from the α/β interface and are propagated inside the α grains. It was observed that α/β interface does not follow Burgers orientation relationship and acts as an obstacle for slip transfer resulting in LABs formation. Such microstructural development at a higher strain amplitude reduces the friction stress which results in cyclic softening.
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•Cyclic loading performed for mill annealed Ti-6Al-4V in strain control mode at high strain amplitude.•Cyclic softening is mostly by lowering of friction stress.•Transmission Kikuchi diffraction (TKD) along with TEM have been employed for the microstructure characterization.•The low angle boundaries appear to originate from α/β-interface and form the sub-grain with lower dislocation density.
Climate change and consequent variations in temperature pose a significant challenge for sustaining wheat production systems globally. This study analyzed the potential impact of rising temperature ...on wheat yield in the north Indian plains, India’s central wheat-growing region, using panel data from 1981 to 2009. This study deviates from most previous studies by including non-climatic factors in estimating the impact of climate change. To determine the differential impact of increased temperature at various growth stages, two temperature measures were used to fit the function, Growing Season Temperature (GST), and Terminal Stage Temperature (TST). Analysis revealed that there was a significant rise in both GST and TST during the study period. The magnitude of the annual increment in TST was twice that of GST. Wheat yield growth in the region was driven primarily by increased input resources such as fertilizer application and technological development like improved varieties and management practices. Most importantly, the study found that the extent of yield reduction was more significant for an increase in temperature at terminal crop growth stages. The estimated yield reduction due to unit increase in TST was 2.26%, and GST was 2.03%.
The α - β titanium alloy VT31 is used in the aerospace industry due to its high strength to weight ratio and good mechanical properties at elevated temperatures. Surface microstructure plays an ...important role in the mechanical behavior of the material, especially fatigue. In this work, VT3-1 α - β titanium alloy surface microstructure was modified using laser surface heat treatment. Laser surface treatment (LST) was carried out at various laser powers (100−250 W) and scanning speeds (150−500 mm/min). Laser affected zones, surfaces and sub-surfaces were characterized using different techniques. Electron backscatter diffraction (EBSD) analysis of the laser affected zone exhibits a distinct microstructure across the depth of the specimen, and it changes with laser power and scanning speed. At a lower scanning speed and high laser power (200−250 W); almost complete β-containing microstructure was developed at the surface with very high hardness. At an intermediate power (150−200 W), a β -rich surface layer with dendritic features followed by a layer of martensitic microstructure was evident. Interestingly, at high power (250 W) a distinct shiny surface with a lower surface roughness was observed. Moreover, the microstructure under this condition corresponds to an α-phase (transformed microstructure) which is typical of melted and fast cooled α - β titanium alloy. Finite element analysis of the LST was also carried out to predict thermal history based on which the extent of the laser affected zone across the depth was predicted for various processing parameters and correlated with the hardness variation.
Malaria in the rural and remote regions of tropical countries remain a major public health challenge. Early diagnosis and prompt effective treatment are the basis for the management of malaria and ...for reducing malaria mortality and morbidity worldwide and the key to malaria elimination. While Rapid Diagnostic Test (RDT) remains the current mainstay testing malaria infections, it is usually used in conjunction with clinical findings and lab tests of blood films through Microscopy, the gold standard of malaria diagnosis. Recent reports suggest that the accuracy of RDTs could be compromised due to parasite antigen gene deletion(s), and the lack of expertise and high turnover time makes microscopy impractical to be used in rural and remote areas which impede the diagnosis and treatment of the disease. Delay in receiving treatment for uncomplicated malaria is reported to increase the risk of developing severe malaria and mortality. Thus, the need to develop advanced, faster, and smarter tools for malaria diagnosis is paramount, specially to reinforce the gold standard method, i.e., malaria microscopy which is a full-proof tool given the limitations be addressed. Deep learning-based methods have proven to provide human expert level performance on object detection/classification on image data. Such methods can be utilized for automation of repetitive task in assessing large number of microscope images of blood samples. In this paper, we propose a novel approach to improve the performance of deep learning models through consistent labelling of ground truth bounding box for the task of pathogen detection on microscope images of thick blood smears. Recommendations are made on the reliability and repeatability testing of the trained models. A custom deep learning architecture (YOLO-mp) is developed based on the design criteria of optimizing accuracy and speed of detection with minimal resources. The custom three-layered YOLO-mp-3l and four-layered YOLO-mp-4l models achieved the best mAP scores of 93.99 (@IoU=0.5) and 94.07 (@IoU=0.5), respectively outperforming standard YOLOv4 (mAP 92.56 @IoU=0.5) for detection of malaria pathogen on a public dataset of thick smear microscopic images captured using phone camera. YOLO-mp-3l (BFLOPs= 21.8, model size=24.5Mb) and YOLO-mp-4l (BFLOPs=24.477, model size=25.4Mb) outperformed standard YOLOv4 (BFLOPs=127.232, model size=244Mb) in terms of computation and memory requirements proving them suitable to run on low resource devices.
The present work deals with the enhancement of the tensile strength of AA 6063 plates welded by the GTAW technique using AA 5356 filler metal sprayed with TiB2 nanoparticles (0, 4, 8 and 12 wt%). ...Advanced characterization techniques were used to observe microstructural variations and correlate them with the properties of the tensile curves. The X-ray profiles revealed the absence of a thermochemical reaction, variations in the position and intensity of the α-Al peak in the weldment. The IPF micrographs revealed the refined grains in the α-Al phase owing to the incorporation of TiB2 nanoparticles which prevented the nucleation of grain growth according to the Zener pinning effect (0 and 12 wt% TiB2 weld: 103 ± 8 and 26 ± 8 μm, respectively). The pole figures show that the weakened texture in the planes can be attributed to the severe deformation of the grains (0 and 12 wt% TiB2 weld: 6.086 and 1.842, respectively). The engendered strain fields and accumulated dislocations enhanced the load-carrying ability of α-Al weldments. These factors improved the mechanical strength of the weld. The 12 wt%TiB2/α-Al weld demonstrated the higher work hardening rate. Increases in the strain hardening exponent provided more plastic properties and a decreased relative slip distance extended the occurrence of deformation during tension.
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•Developed AA6063-AA5356/TiB2 nano-composite by GTAW.•Investigated detailed microstructural evolutions.•Examined the work hardening and relative slip-distance.
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