Climate change and monsoons: a paleo perspective

History repeats” goes a popular adage. Thus, by understanding monsoons in the ancient climates that are analogous to what is expected in the future, we can develop more confidence in the prediction of 21st century climate and be prepared accordingly. Monsoons of the distant past are inferred through indirect measurements, called proxies. Proxies suggest that monsoon strength has varied in step with periodic oscillations in the Sun-Earth geometry. These oscillations with periods 23 ky, 41 ky, and 100 ky (years – y, 1000 years - ky) modulate the solar radiation reaching the Earth. The growth and decay of ice sheets and the rise and fall of greenhouse gas concentrations in the atmosphere through the ice ages also modulate the monsoons. An emerging theory of monsoons known as “energetics of monsoons” can decipher the impact of these climate drivers and the ensuing feedbacks. We find that long-term monsoon evolution is determined by only two variables: the net energy flux into the atmosphere and water vapor. Furthermore, we have shown that the energy released by the oceans plays a crucial role in determining the local rainfall over the oceans. The anthropogenic global warming will enhance the moisture content in the atmosphere and lead to an increase in the monsoon rainfall

Response of the low-level jet to precession and its implications for proxies of the Indian Monsoon

The long-term variations in the South Asian monsoon have been inferred based on the variations in the ocean productivity along the western coast of the Arabian Sea. The variations in ocean productivity were previously thought to be primarily influenced by the intensity of upwelling. Here, using idealized precession experiments in fully coupled climate models, we have shown that the area as well as the region of maximum upwelling change with precession. When summer occurs at perihelion (stronger summer insolation and monsoon precipitation), the area of upwelling is narrow. In contrast, during summer at aphelion (weaker summer insolation and monsoon precipitation), upwelling occurs over a broader region. This is due to the effect of convective heating over northeastern Africa and the western equatorial Indian Ocean on the width and meridional location of the low-level jet. Therefore, the upwelling inferred from proxies does not necessarily indicate the Indian summer monsoon strength. © 2022. American Geophysical Union. All Rights Reserved

DESIGN, SYNTHESIS, AND EVALUATION OF NEW DERIVATIVE OF 1,2,4-TRIAZOLES FOR ANTIMICROBIAL AND ANTI-INFLAMMATORY ACTIVITY

Objective: The object of the study is to design, synthesize and biological evaluation of isoniazid derived 1,2,4-triazoles compounds.Methods: Isoniazid based 1,2,4-triazoles derivatives have been synthesized by reaction of Isoniazid with carbon disulfide in basic medium (KOH) to form Potassium dithiocarbazinate salt and reaction with hydrazine hydrate converted into 4-amino-5-(pyridin-4-yl)-4H-1,2,4-triazole-3-thiol. These compounds were reacted with seven different benzaldehyde to form 4-[(substituted phenyl)-methylene]-amino-5-(pyridine-4-yl)-4H-1,2,4-triazol-3-thiol (4). The final compounds were synthesized by reaction with four different acetanilide to form 4-[substituted phenyl)-methylene]-amino-3-(N-substitutedcarboxamidomethylthio)-5-(pyridine-4-yl)-4H-1,2,4-triazoles derivatives. All these compounds were characterized by IR, 1H-NMR, [13]C-NMR and elemental analysis. The antimicrobial activity was determined by the cup plate method. Acute anti-inflammatory activity determined by using carrageenan-induced rat paw edema model.Results: Series PJ-A4, PJ-A7 and PJ-A13 showed more than 90% of the zone of inhibition against both Gram positive and Gram negative organisms. The antifungal study suggested that among synthesized compounds series PJ-A4, A7, A9, A11 and A13 showed more than 90% of zone of inhibition, A2, A10 and A12 shows more than 80% of the zone of inhibition. Anti-inflammatory study data indicate that compounds PJ-A4, PJ-A8, PJ-A9 and PJ-A13 produced 70 to 76% of paw edema inhibition compare to standard drug Ibuprofen which showed 83.3% after 5 h. Conclusion: Results suggested that the isoniazid based 1,2,4-triazole derivatives have significant antibacterial, antifungal and anti-inflammatory activity

The response of tropical precipitation to Earth's precession: the role of energy fluxes and vertical stability

The changes in Earth's precession have an impact on the tropical precipitation. This has been attributed to the changes in seasonal solar radiation at the top of the atmosphere. The primary mechanism that has been proposed is the change in thermal gradient between the two hemispheres. This may be adequate to understand the zonal mean changes, but cannot explain the variations between land and oceans. We have used a simple model of the intertropical convergence zone (ITCZ) to unravel how precipitation changes with precession. Our model attributes the changes in precipitation to the changes in energy fluxes and vertical stability. We include the horizontal advection terms in this model, which were neglected in the earlier studies. The final response of the land and oceans is a result of complex feedbacks triggered by the initial changes in the insolation. We find that the changes in precipitation over the land are mainly driven by changes in insolation, but over the oceans, precipitation changes on account of changes in surface fluxes and vertical stability. Hence insolation can be a trigger for changes in precipitation on orbital timescales, but surface energy and vertical stability play an important role too. The African monsoon intensifies during a precession minimum (higher summer insolation). This intensification is mainly due to the changes in vertical stability. The precipitation over the Bay of Bengal decreases for minimum precession. This is on account of a remote response to the enhanced convective heating to the west of the Bay of Bengal. This weakens the surface winds and thus leads to a decrease in the surface latent heat fluxes and hence the precipitation.</p

Synthesis, molecular docking, antiproliferative and radical scavenging activities of vanillin derived 1,3,5-trisubstituted 2-pyrazolines

Observing the good anticancer potential of 2-pyrazoline scaffold, a panel of 1,3,5- trisubstituted 2- pyrazolinesnamely, 5-(4-hydroxy-3-methoxyphenyl)-3-(4-substitutedphenyl)4,5-dihydro-1H-pyrazol-1 yl)(phenyl)methanones 2a-j and (5-(4-hydroxy-3-methoxyphenyl)-3-(4-substituted phenyl)4,5-dihydro-1H-pyrazol-1-yl)(pyridin-4-yl)methanones 3a-j have been synthesized from the chalcone intermediates derived from the reaction between vanillin and substituted acetophenones, by condensing with benzhydrazide and isonicotinic acid hydrazide, respectively. The synthesized compounds have been characterized by spectral studies and screened for in vitro antiproliferative activity against human non small cell lung cancer cell line A549 by MTT assay and antioxidant activity by DPPH radical scavenging assay. The compound 2i has exhibited good antiproliferative activity followed by 2g and 2a. Compounds of both series 2a-j and 3a-j exhibited good radical scavenging activity. Molecular docking studies of 2h and 2j has revealed the good interaction with 3LCT (Crystal structure of anaplastic lymphoma kinase catalytic domain) receptor via hydrogen bonds, electrostatic and hydrophobic interactions. The drug-likeness properties of the compounds were also satisfactory leaving a good scope for further work

Low incidence of positive smooth muscle antibody and high incidence of isolated IgM elevation in Chinese patients with autoimmune hepatitis and primary biliary cirrhosis overlap syndrome: a retrospective study

<p/> <p>Background</p> <p>Up to now, few data are available regarding the clinical characteristics of autoimmune hepatitis and primary biliary cirrhosis overlap syndrome. The study was to investigate and analyze the prevalent and clinical features of Chinese patients with this disease.</p> <p>Methods</p> <p>Clinical data on patients diagnosed as autoimmune hepatitis and primary biliary cirrhosis overlap syndrome in our hospital from January 2001 to December 2006 were collected and analyzed.</p> <p>Results</p> <p>Overlap syndrome of autoimmune hepatitis and primary biliary cirrhosis accounted for 10.33% of patients with autoimmune liver diseases during the past six years. For these patients with overlap syndrome, xanthochromia, lethargy and anorexia were the predominant complaints; a low incidence (14/146) of smooth muscle antibody positivity and a high incidence (37/89) of isolated IgM elevation were the main serological characteristics.</p> <p>Conclusions</p> <p>Overlap syndrome of autoimmune hepatitis and primary biliary cirrhosis was not rare in Chinese patients with clinical manifests of autoimmune liver diseases. Overlap of the diseases should not be disregarded when isolated IgM elevation was exhibited, and smooth muscle antibody might have little diagnostic significance in the overlap syndrome. If it was difficult to make a definite diagnosis, liver biopsy was necessary.</p