In the present research work, an effort has been made to examine the effect of the ERNiCrCoMo-1 filler on solidification mechanism, microstructural characterization, welded joint integrity, and ...residual stresses of the dissimilar welded joint (DWJ) of martensitic grade P92 steel and Ni-based superalloy Inconel 617 for advanced ultra-supercritical (A-USC) power plant application. Weld joints have been fabricated for V groove geometry by using the multipass gas tungsten arc welding (GTAW) process. The multiple aspects of the welded joint structural integrity have been tested by performing the tensile test, microhardness tests and Charpy impact test. The ERNiCrCoMo-1 weld solidified in austenitic mode with columnar and cellular dendrites in the interior region, while columnar dendrites were observed near the interface region. The unmixed zone (UZ) formation was noticed at the ERNiCrCoMo-1 filler weld and P92 steel interface, while the UZ gets eliminated at Inconel 617 interface. The microstructural observation near the interface showed that migrated grain boundaries were observed frequently near the lower region of the weld metal (WM), while at the interface of the P92 steel and ERNiCrCoMo-1 filler welds, higher density of soft
δ
ferrite patches for the capping and backing passes were observed. The energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD) results confirmed the presence of the Cr- and Mo-enriched M
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C
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precipitates, Mo-enriched M
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C and Ti-enriched Ti(C, N) precipitates in the WM. Acceptable mechanical properties were obtained at room temperature. The Charpy impact toughness (CIT) was observed 98 ± 5 J and 108 ± 3 J for WM with V notch at the top and root region, respectively. The dramatic reduction in CIT was after the postweld heat treatment (PWHT) was attributed to the evolution of the carbide particles in interdendritic areas. Tensile strength results of the cross-weld specimen showed the tensile strength value marginally lower than the P92 steel but significantly lower than the Inconel 617 base metal in both as-welded (AW) and PWHT condition along with fracture in the week region of P92 steel. The failure from the region of P92 steel instead of the ERNiCrCoMo-1 filler WM confirmed that the welded joint was safe for A-USC power plants boiler application. A significant heterogeneity in microhardness was seen along the weldments with a peak hardness of 445 ± 8 in P92 CGHAZ and a lower hardness of 181 HV in the peninsula. The increase in microhardness of the WM as a result of PWHT was attributed to the evolution of the carbide particles in the WM. Through thickness residual stresses variation was also measured for both WM and HAZ region and the effect of the PWHT on the magnitude and nature of the residual stresses were also performed. Hence the work provides insight into welding procedure development, microstructural evolution in the WM and HAZ, variation in mechanical properties, and residual stresses variation for the welded joint of P92 steel and Inconel 617 alloy.
Mechanical properties of creep enhanced ferritic (CSEF) steels is affected by various parameters, the solutionizing temperature is one of them. The present work demonstrates the effect of ...solutionizing temperature on microstructure and mechanical properties of CSEF P91 steel. Optical metallography (OM) and Scanning electron microscopy (SEM) were carried out to study the microstructure of P91 steel in different heat treatment conditions. In order to determine the precipitates present in microstructure; X-ray analysis was performed. Moreover, the influence of solutionizing temperature on the mechanical properties (strength, hardness and impact toughness) has also been studied.
•SEM-EDS analysis of P91 steel precipitates present at grain boundary and grain interior were carried out.•For constant tempering time effect of normalizing temperature on precipitate size, particle-to particle distance, and grain size were carried out.•Effect of normalizing temperature on tensile strength, yield strength, hardness, % elongation and % reduction of area of P91 steel were studied.•For constant tempering time effect of normalizing temperature on room temperature impact toughness of P91 steel were studied. Fracture surface after impact testing were also characterized by using SEM.•Fracture surface after room temperature tensile testing were also characterized by using SEM to study the effect of normalizing temperature on fracture surface.
Abstract Using long-term X-ray observations, we present short-term and long-term X-ray variability analysis of the ultrafast rotating active star AB Dor. Flaring events are common in X-ray ...observations of AB Dor and occupy a substantial portion of the total observation time, averaging at around 57% ± 23%. The flare-free X-ray light curves show rotational modulation, indicating the presence of highly active regions in the star's corona. We have developed a light-curve inversion code to image the corona of active fast rotating stars. The results of coronal imaging reveal the presence of two active regions of different brightness that are separated by ∼180° in longitude. These active regions are also found to migrate along the longitude and also show variation in their brightness. Our analysis of long-term X-ray data spanning from 1979 to 2022 shows multiple periodicities. The existence of a ∼19.2 yr cycle and its first harmonic indicates the presence of a solar-like, long-term pattern. In comparison, the periodicities of ∼3.6 and ∼5.4 yr are possibly due to the presence of a flip-flop cycle in the X-rays, which is also supported by findings for similar periods from the optical data in earlier studies. Further confirmation of the existence of the X-ray flip-flop cycle requires long-term observations at regular intervals in the quiescent state.
This paper reviews dissimilatory nitrate reduction to ammonium (DNRA) in soils - a newly appreciated pathway of nitrogen (N) cycling in the terrestrial ecosystems. The reduction of NO3− occurs in two ...steps; in the first step, NO3− is reduced to NO2−; and in the second, unlike denitrification, NO2− is reduced to NH4+ without intermediates. There are two sets of NO3−/NO2− reductase enzymes, i.e., Nap/Nrf and Nar/Nir; the former occurs on the periplasmic-membrane and energy conservation is respiratory via electron-transport-chain, whereas the latter is cytoplasmic and energy conservation is both respiratory and fermentative (Nir, substrate-phosphorylation). Since, Nir catalyzes both assimilatory- and dissimilatory-nitrate reduction, the nrfA gene, which transcribes the NrfA protein, is treated as a molecular-marker of DNRA; and a high nrfA/nosZ (N2O-reductase) ratio favours DNRA. Recently, several crystal structures of NrfA have been presumed to producee N2O as a byproduct of DNRA via the NO (nitric-oxide) pathway. Meta-analyses of about 200 publications have revealed that DNRA is regulated by oxidation state of soils and sediments, carbon (C)/N and NO2−/NO3− ratio, and concentrations of ferrous iron (Fe2+) and sulfide (S2−). Under low-redox conditions, a high C/NO3− ratio selects for DNRA while a low ratio selects for denitrification. When the proportion of both C and NO3− are equal, the NO2−/NO3− ratio modulates partitioning of NO3−, and a high NO2−/NO3− ratio favours DNRA. A high S2−/NO3− ratio also promotes DNRA in coastal-ecosystems and saline sediments. Soil pH, temperature, and fine soil particles are other factors known to influence DNRA. Since, DNRA reduces NO3− to NH4+, it is essential for protecting NO3− from leaching and gaseous (N2O) losses and enriches soils with readily available NH4+-N to primary producers and heterotrophic microorganisms. Therefore, DNRA may be treated as a tool to reduce ground-water NO3− pollution, enhance soil health and improve environmental quality.
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•DNRA is a novel and shortest biological pathway of N-cycling in terrestrial ecosystems where NO3- is reduced to NH4+ in soils•This pathway has potential to reduce N2O emissions and protect NO3- from leaching losses•It outcompetes the denitrification process under limited NO3- availability in the system•It enriches soil with NH4+-N and make available to primary producers as N-fertilizer•Meta-analyse revealed that DNRA is mainly regulated by C/N ratio, NO2- / NO3- ratio and S2-
Proteolytic enzymes are crucial for a variety of biological processes in organisms ranging from lower (virus, bacteria, and parasite) to the higher organisms (mammals). Proteases cleave proteins into ...smaller fragments by catalyzing peptide bonds hydrolysis. Proteases are classified according to their catalytic site, and distributed into four major classes: cysteine proteases, serine proteases, aspartic proteases, and metalloproteases. This review will cover only cysteine proteases, papain family enzymes which are involved in multiple functions such as extracellular matrix turnover, antigen presentation, processing events, digestion, immune invasion, hemoglobin hydrolysis, parasite invasion, parasite egress, and processing surface proteins. Therefore, they are promising drug targets for various diseases. For preventing unwanted digestion, cysteine proteases are synthesized as zymogens, and contain a prodomain (regulatory) and a mature domain (catalytic). The prodomain acts as an endogenous inhibitor of the mature enzyme. For activation of the mature enzyme, removal of the prodomain is necessary and achieved by different modes. The pro-mature domain interaction can be categorized as protein-protein interactions (PPIs) and may be targeted in a range of diseases. Cysteine protease inhibitors are available that can block the active site but no such inhibitor available yet that can be targeted to block the pro-mature domain interactions and prevent it activation. This review specifically highlights the modes of activation (processing) of papain family enzymes, which involve auto-activation, trans-activation and also clarifies the future aspects of targeting PPIs to prevent the activation of cysteine proteases.
The new generation super critical thermal power plants are required to operate at enhanced thermal efficiency of over 50% to reduce the fuel consumption and environmental pollution. Creep ...strength-enhanced ferritic steels, commonly known as Cr-Mo alloys such as P91 (X10CrMoVNb 9-1) are such material of choice for the next generation power plants. The operating requirement of these next generation power plants is that steam temperature of around 650 °C is maintained. For such high-temperature application, creep strength of material is the primary consideration together with adequate weld heat-affected zone (HAZ) toughness. Present work deals with the effect of high service temperature on impact toughness of P91 (X10CrMoVNb 9-1) base material, weld fusion zone, and HAZ. The impact toughness of HAZ for conventional weld groove design and narrow weld groove design has been evaluated experimentally in as-welded and at different post-weld heat treatment conditions. Fractography of the impact toughness specimens of base metal, weld fusion zone, and HAZ was carried out using scanning electron microscope. The effects of heat treatment schemes on the percentage of element present at the fracture surface were also studied.
Abstract Binge drinking is common during adolescence and can lead to the development of psychiatric disorders, including alcoholism in adulthood. Here, the role and persistent effects of histone ...modifications during adolescent intermittent ethanol (AIE) exposure in the development of anxiety and alcoholism in adulthood were investigated. Rats received intermittent ethanol exposure during post-natal days 28–41, and anxiety-like behaviors were measured after 1 and 24 h of the last AIE. The effects of AIE on anxiety-like and alcohol-drinking behaviors in adulthood were measured with or without treatment with the histone deacetylase (HDAC) inhibitor, trichostatin A (TSA). Amygdaloid brain regions were collected to measure HDAC activity, global and gene-specific histone H3 acetylation, expression of brain-derived neurotrophic factor (BDNF) and activity-regulated cytoskeleton-associated (Arc) protein and dendritic spine density (DSD). Adolescent rats displayed anxiety-like behaviors after 24 h, but not 1 h, of last AIE with a concomitant increase in nuclear and cytosolic amygdaloid HDAC activity and HDAC2 and HDAC4 levels leading to deficits in histone (H3-K9) acetylation in the central (CeA) and medial (MeA), but not in basolateral nucleus of amygdala (BLA). Interestingly, some of AIE-induced epigenetic changes such as, increased nuclear HDAC activity, HDAC2 expression, and decreased global histone acetylation persisted in adulthood. In addition, AIE decreased BDNF exons I and IV and Arc promoter specific histone H3 acetylation that was associated with decreased BDNF, Arc expression and DSD in the CeA and MeA during adulthood. AIE also induced anxiety-like behaviors and enhanced ethanol intake in adulthood, which was attenuated by TSA treatment via normalization of deficits in histone H3 acetylation of BDNF and Arc genes. These novel results indicate that AIE induces long-lasting effects on histone modifications and deficits in synaptic events in the amygdala, which are associated with anxiety-like and alcohol drinking behaviors in adulthood.
The bacterial genus Exiguobacterium accommodates many versatile species isolated from diverse environments. Exiguobacterium was described as a genus approximately three decades ago, and now, 17 ...species, growing over a broad range of temperatures and pH, have been recognized. Various isolates from different niches have been explored for biotechnological and industrial purposes, including enzyme production, bioremediation and degradation of toxic substances released into the environment. Some isolates possess plant growth promoting capabilities, and they are currently being explored for increasing agricultural production. The genome sequences of various strains of this genus have shown the presence of many genes encoding products of importance to agriculture and the environment. In addition, many strains possess stress-responsive genes helping them to colonize and thrive in diverse ecological niches. This review provides a broad view of the versatile genus Exiguobacterium and its potential for applications in agriculture, the environment and industry, as well as the underlying genomic determinants that drive its diversity and adaptability to various extreme environments.
Background & objectives: Due to lack of appropriate statistical knowledge, published research articles contain various errors related to the design, analysis and interpretation of results in the area ...of biomedical research. If research contains statistical error, however, costly, it may be of no use and the purpose of the investigation gets defeated. Many biomedical research articles published in different peer reviewed journals may retain several statistical errors and flaws in them. This study aimed to examine the trend and status of application of statistics in biomedical research articles. Study design, sample size estimation and statistical measures are crucial components of a study. These points were evaluated in published original research articles to understand the use or misuse of statistical tools.
Methods: Three hundred original research articles from the latest issues of selected 37 journals were reviewed. These journals were from the five internationally recognized publication groups (CLINICAL KEY, BMJ Group, WILEY, CAMBRIDGE and OXFORD) accessible through the online library of SGPGI, Lucknow, India.
Results: Among articles assessed under present investigation, 85.3 per cent (n=256) were observational, and 14.7 per cent (n=44) were interventional studies. In 93 per cent (n=279) of research articles, sample size estimation was not reproducible. The simple random sampling was encountered rarely in biomedical studies even though none of the articles was adjusted by design effect and, only five articles had used randomized test. The testing of assumption of normality was mentioned in only four studies before applying parametric tests.
Interpretation & conclusions: In order to present biomedical research results with reliable and precise estimates based on data, the role of engaging statistical experts need to be appreciated. Journals must have standard rules for reporting study design, sample size and data analysis tools. Careful attention is needed while applying any statistical procedure as, it will not only help readers to trust in the published articles, but also rely on the inferences the published articles draw.
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