Examining chlorophyll-a concentrations in tropical reservoirs under various land use changes using Sentinel - 2 and Google Earth engine - Bhadra and Tungabhadra, India.

The understanding of spatio-temporal variation in land use and land cover (LULC) patterns is crucial for managing catchment land use planning, as it directly influences of tropical reservoir water quality and the subsequent Nutrient Contamination (NC) of unmonitored water bodies. The current research attempts to accurately measure the influence of LULC and its associated determinants on the quantities of NC loads by using Chl-a as a proxy, within tropical reservoirs, i.e. Bhadra and Tungabhadra, located in same river catchment. This Chl-a spread calculated by the Maximum Chlorophyll Index (MCI) derived from Sentinel 2 satellite data products covering the period from July 2016 to June 2021 were done using Google Earth Engine (GEE) platform. The validation analysis confirms the robustness of the methodology with a strong correlation between MCI-calculated values and EOMAP (Earth Observation and Environmental Services Mapping) Chl-a (µg/L) data points for both reservoirs, Bhadra (R2 = 0.64) and Tungabhadra (R2 = 0.68). The findings reveal that, Tungabhadra reservoir consistently exhibits an excessive spatial distribution of Chl-a spread area (17 km2 to 335 km2), reflecting nutrient-rich water inflows, particularly evident during the post-monsoon period. This notable rise could be linked to harvesting the Kharif crop, resulting in elevated nutrient concentrations. In contrast Bhadra reservoir, dominated by forested areas, maintains relatively lower Chl-a spread areas (<20 km2), highlighting its pivotal role in maintaining water cleanliness and serves as a riparian boundary. In addition, the changes in LULC classes show a strong relationship with variation in Chl-a during the studied period, for the Bhadra Reservoir R2 = 0.51 (F- statistics = 3.983, p = 0.021), and the Tungabhadra Reservoir R2 = 0.802 (F- statistics = 7.489, p = 0.0143). This highlights how changes in land use significantly shape contamination dynamics, deepening our understanding of nutrient inputs and contamination drivers in tropical reservoirs.

Detection and mapping of water and chlorophyll-a spread using Sentinel-2 satellite imagery for water quality assessment of inland water bodies.

Water quality monitoring of reservoirs is currently a significant challenge in the tropical regions of the world due to limited monitoring stations and hydrological data. Remote sensing techniques have proven to be a powerful tool for continuous real-time monitoring and assessment of tropical reservoirs water quality. Although many studies have detected chlorophyll-a (Chl-a) concentrations as a proxy to represent nutrient contamination, using Sentinel 2 for eutrophic or hypereutrophic inland water bodies, mainly reservoirs, minimal efforts have been made for oligotrophic and mesotrophic reservoirs. The present study aimed to develop a modeling framework to map and estimate spatio-temporal variability of Chl-a levels and associated water spread using the Modified Normalized Difference Water Index (MNDWI) and Maximum Chlorophyll Index (MCI). Moreover, the impact of land use/land cover type of the contributing watershed in the oligo-mesotrophic reservoir, Bhadra (tropical reservoir), for 2018 and 2019 using Sentinel 2 satellite data was analyzed. The results show that the water spread area was higher in the post-monsoon months and lower in the summer months. This was further validated by the correlation with reservoir storage, which showed a strong relationship (R2 = 0.97, 2018; R2 = 0.93, 2019). The estimated Chl-a spread was higher in the winter season, because the reservoir catchment was dominated by deciduous forest, producing a large amount of leaf litter in tropical regions, which leads to an increase in the level of Chl-a. It was found that Chl-a spread in the reservoir, specifically at the inlet sources and near agricultural land practices (western parts of the Bhadra reservoir). Based on the findings of this study, the MCI spectral index derived from Sentinel 2 data can be used to accurately map the spread of Chl-a in diverse water bodies, thereby offering a robust scientific basis for effective reservoir management.

Functionalized Graphene Quantum Dot Interfaced Electrochemical Detection of Cardiac Troponin I: An Antibody Free Approach.

According to the World Health Organization (WHO), cardiovascular disease (CVD) is the leading cause of death in the world every year. The design and development of biosensors for the detection of CVD markers could be one of the major contributions of the scientific community to society. In this context, acetic acid functionalized graphene quantum dots (fGQDs) were used as an interface for the electrochemical detection of cardiac Troponin I (cTnI). The interaction of cTnI with fGQDs for the early diagnosis of acute myocardial infarction was investigated using cyclic voltammetry (CV) and amperometry. The carbodiimide conjugation between the N-H group of cTnI and the functionalized COOH group on GQDs enabled the detection of cTnI biomarker. The same sensing mechanism was confirmed using Fourier Transform Infrared Spectrometry (FTIR). The fGQDs modified Au electrode showed remarkable electrocatalytic oxidation of cTnI with good stability and sensitivity over a linear range of 0.17 to 3 ng mL-1 and a low detection limit of 0.02 ng mL-1. Bland-Altman plots substantiate a bias between the intra-/inter-cTnI assay and calibrated cTnI assay with 95% limits of agreement (mean difference ± 1.96 SD). The aim of this study is to describe an innovative method to detect cardiac biomarker cTnI and provide preliminary data on its diagnostic capacity. At the same time, its applicability in clinical setting will have to be validated with a significant number of samples collected from patients.

Heterogeneous polymer composite nanoparticles loaded in situ gel for controlled release intra-vaginal therapy of genital herpes.

Herpes simplex virus causes serious and contagious genital infections in high percentage of female population world-wide. Acyclovir is a clinically successful antiviral molecule till date, in-spite of limitations as poor solubility, low half-life, reduced oral bioavailability and side effects at higher doses. In the present work, controlled release in situ gelling system loaded with polymeric nanoparticles of acyclovir containing a dose of drug equivalent to 105mg/day has been developed. The formulation containing drug loaded polyvinyl pyrrolidone-Eudragit RSPO hybrid polymeric nanoparticles (Size ∼99±3nm, Zeta ∼+26.1±1.5mV) in 15% Pluronic F-127 gel exhibited improved permeability through vaginal membrane (KP=2.20±0.19×10(-6)cm/s). The nanoparticles showed enhanced viability for vaginal epithelial cell lines up to concentration of 100-250µg/mL. The formulation was evaluated for bioavailability and biodistribution through intra-vaginal administration in rat models. The nanoparticle in situ gel formulation maintained an average therapeutic drug level of 0.6±0.2µg/mL in plasma for 24h. Significant improvement in mean residence time of the drug (12.52±1.12h) was observed with a two-fold increase in the relative bioavailability (AUC0-24h=14.92±2.44µgh/mL) compared to that of the pure drug (7.18±1.79µgh/mL). The tissue distribution was 2-3 folds higher in animals treated with nanoparticles in situ gel compared to that of pure drug. Sustained release of drug in vivo was demonstrated, ensuring the suitability of the formulation for clinical therapy in female population.

Preparation and Thermo-Physical Properties of Fe2O3-Propylene Glycol Nanofluids.

Iron oxide (Fe2O3) nanoparticles were prepared from ferric chloride and ferrous sulphate by precipitation reaction. Fe2O3-propylene glycol nanofluid was prepared by dispersing Fe2O3 nanoparticles in propylene glycol through stirred bead milling, shear homogenization and probe ultrasonication. The nanofluid was characterized through measurement of viscosity, particle size distribution and thermal conductivity. The interactions between Fe2O3 nanoparticles and propylene glycol on the nanoparticle surfaces lead to reduction in viscosity, the magnitude of which increases with nanoparticle concentration (0-2 vol%) at room temperature. The thermal conductivity enhancement for 2 vol% nanofluid was about 21% at room temperature, with liquid layering being the major contributor for thermal conductivity enhancement.

Scientific Insights in the Preparation and Characterisation of a Lead-based Naga Bhasma.

Naga bhasma is one of the herbo-metallic preparations used in Ayurveda, a traditional Indian System of Medicine. The preparation of Naga bhasma involves thermal treatment of 'Naga' (metallic lead) in a series of quenching liquids, followed by reaction with realgar and herbal constituents, before calcination to prepare a fine product. We have analysed the intermediates obtained during different stages of preparation to understand the relevance and importance of different steps involved in the preparation. Our results show that 'Sodhana' (purification process) removes heavy metals other than lead, apart from making it soft and amenable for trituration. The use of powders of tamarind bark and peepal bark maintains the oxidation state of lead in Jarita Naga (lead oxide) as Pb(2+). The repeated calcination steps result in the formation of nano-crystalline lead sulphide, the main chemical species present in Naga bhasma.

Variations in physicochemical properties of a traditional mercury-based nanopowder formulation: need for standard manufacturing practices.

Rasasindura is a mercury-based nanopowder synthesized using natural products through mechanothermal processing. It has been used in the Ayurvedic system of medicine since time immemorial for various therapeutic purposes such as rejuvenation, treatment of syphilis and in genital disorders. Rasasindura is said to be composed of mercury, sulphur and organic moieties derived from the decoction of plant extracts used during its synthesis. There is little scientific understanding of the preparation process so far. Though metallic mercury is incorporated deliberately for therapeutic purposes, it certainly raises toxicity concerns. The lack of gold standards in manufacturing of such drugs leads to a variation in the chemical composition of the final product. The objective of the present study was to assess the physicochemical properties of Rasasindura samples of different batches purchased from different manufacturers and assess the extent of deviation and gauge its impact on human health. Modern characterization techniques were employed to analyze particle size and morphology, surface area, zeta potential, elemental composition, crystallinity, thermal stability and degradation. Average particle size of the samples observed through scanning electron microscope ranged from 5-100 nm. Mercury content was found to be between 84 and 89% from elemental analysis. Despite batch-to-batch and manufacturer-to-manufacturer variations in the physicochemical properties, all the samples contained mercury in the form of HgS. These differences in the physicochemical properties may ultimately impact its biological outcome.

Assessing forest canopy closure in a geospatial medium to address management concerns for tropical islands--Southeast Asia.

The present study outlines an approach to classify forest density and to estimate canopy closure of the forest of the Andaman and Nicobar archipelago. The vector layers generated for the study area using satellite data was validated with the field knowledge of the surveyed ground control points. The methodology adopted in this present analysis is three-tiered. First, the density stratification into five zones using visual interpretation for the complete archipelago. In the second step, we identified two island groups from the Andaman to investigate and compare the forest strata density. The third and final step involved more of a localised phytosociological module that focused on the North Andaman Islands. The results based on the analysis of the high-resolution satellite data show that more than 75% of the mangroves are under high- to very high-density canopy class. The framework developed would serve as a significant measure to forest health and evaluate management concerns whilst addressing issues such as gap identification, conservation prioritisation and disaster management--principally to the post-tsunami assessment and analysis.

Validation of the LC-MS/MS method for the quantification of mevalonic acid in human plasma and determination of the matrix effect.

A simple, specific, and sufficiently sensitive liquid chromatography-tandem mass spectrometry (negative-ion electrospray ionization) methodology to determine mevalonic acid (MVA) in human plasma is described, and its application to the analysis of rat plasma MVA levels after rosuvastatin administration is demonstrated. The method was validated over the linearity range of 0.5-50.0 ng/ml (r(2) > 0.99) using deuterated MVA as an internal standard. The lower limit of quantification was 0.5 ng/ml. The assay procedure involved the isolation of MVA from plasma samples using solid-phase extraction. Chromatographic separation was achieved on a HyPurity Advance column with a mobile phase consisting of ammonium formate buffer (10 mM, pH 8.0) and acetonitrile (70:30, v/v). Excellent precision and accuracy were observed. MVA and deuterated mevalonolactone were stable in water and plasma under different storage and processing conditions. The recovery observed was low, which was attributable to a significant matrix effect. A significant decrease (30-40%; P < 0.05) was observed in rat plasma MVA levels after rosuvastatin administration.

Biopolymer metal catalysts for the hydrolysis of nerve gases.

Glucosamine oligomers--monomer through tetramer--form complexes with Cu2+ that catalyse the hydrolysis of the 'nerve gas' 1,2,2-trimethylpropyl- methylphosphonofluroidate (soman) by cleaving the P-F bond. A 1/1 glucosamine/Cu2+ ratio whether as glucosamine or glucosamine units, gives the highest hydrolytic rate over the 11.5/1 to 1/1 range. This trend also appears to hold for a glucosamine polymer, chitosan, which, when complexed with Cu2+ also hydrolyzes soman. The relatively low rate of hydrolysis by this polymer-Cu2+ complex, while not yet explainable, is consistent with an extrapolation of the monomer-through-tetramer series. The question may be raised as to whether these biopolymer metal complexes provide any clues to the involvement of Mn2+ in the functioning of one class of P-F cleaving enzymes.

Studies on the chelation of aluminum for neurobiological application.

The formation and strength of chelation of A1(III) with salicylic acid (SA), citric acid (CIT), ethylenediaminetetraacetic acid (EDTA), ethylenediamine-di-(o-hydroxyphenylacetic acid) (EDDHA), N,N'-di-(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED), and some mixed ligand systems consisting of the above ligands were examined at an ionic strength of 0.12 M NaCl and 25.0 +/- 0.1 degrees C. All the ligands under consideration form strong chelates with A1(III). The order of the stabilities (log KML) of their A1(III) chelates are SA (13.7) less than EDTA (15.3) less than CIT (18.0) less than EDDHA (24.5) approximately equal to HBED (24.8). An equilibrium analysis of the A1(III)-SA (1:1), A1(III)-CIT (1:1) and A1(III)-SA-CIT (1:1:1) systems indicated the occurrence of hydrolysis and polymerization reactions in each one of them. The A1(III)-EDTA (1:1) chelate was found to undergo hydrolysis even at pH 5. However, EDDHA and HBED each formed a very stable mononuclear chelate with A1(III) and did not show hydrolytic or polymerization tendencies.

Role of chelation and water binding of calcium in dormancy and heat resistance of bacterial endospores.

The possible relationship between the water binding by bacterial endospores and their dormancy and heat resistances has been examined in terms of the coordination characteristics of the spore-bound calcium. Stabilities of the calcium complexes of typical cytoplasmic and structural spore components were determined by potentiometric equilibrium pH measurements in model systems consisting of DPA, glycine, alanine, glutamic acid, alanyl-glutamic acid, triglycine, and tetraglycine. The Ca++-form and H+-form spores of Clostridium botulinum 33A were investigated in vivo with respect to their water sorption and heat-resistance characteristics. The results suggest that the complexing of calcium and Ca(II)-DPA may be biologically significant for spore resistance and dormancy at the following three levels: (1) complexing with spore cytoplasmic pool constituents consistent with the idea of a metal-chelate cross-linked cytoplasm or spore cement stabilizing the essential biological macromolecules, (2) complexing with structural components of the spore as indicated by the interaction with model peptides, and (3) coordination with water to produce an apparently dehydrated environment in the spore as evident from the much greater water-sorption capacity of the Ca++-form spores vs the much smaller water sorption of the H+-form spores. Interestingly enough, DPA itself, in the absence of metal ion, showed some interaction with di-, tri-, and tetrapeptides and a weak but detectable interaction with amino acids. Although the exact mode of the DPA-peptide interaction is not clear, it is attractive to speculate about its possible involvement in the control of spore dormancy and resistance.

The effects of cholecystectomy on the bile salt pool of the syrian hamster.

The half-life, distribution, size and composition of the bile salt pool were determined in intact and cholecystectomized Syrian hamsters. Cholecystectomy had no effect on the half-life of either the cholate or chenodeoxycholate pool. Fasting in intact hamsters resulted, as expected, in a shift of bile salts from the small intestine, cecum and liver to the gallbladder. In cholecystectomized hamsters there was a moderate shift of salts from the liver and small intestine to the cecum. Cholecystectomy had no significant effect on the size of the total bile salt pool. The total bile salt pool size of fed and fasted intact hamsters was the same; fasting in cholecystectomized hamsters resulted in a large decrease in the pool. There was no significant difference in the bile salt pool composition of intact and cholecystectomized hamsters, and hamsters were shown to efficiently convert deoxycholate to cholate.

Improved fluoride incorporation and new in vitro fluorine elemental determination.

The CPA technique was shown to be very useful in nondestructively determining the concentration profiles of fluoride in extracted teeth. By means of this technique, it was found that in vitro treatment with K2ZrF6 incorporated substantially more fluoride into the enamel than NaF or APF by factors of 5 and more than 50, respectively. The concentration profile was determined from the tooth surface to a depth of 2.1 mum, with a resolution of 0.07 mum at the surface and 0.15 mum at a 2.1-mum depth. Proton-stimulated X-ray fluorescence was used to detect the elements heavier than Mg, for example, P, Cl, K, Ca, Ti, Fe, Ni, Ca, Zn, Zr, and Pb.

Metal chelates of L-DOPA for improved replenishment of dopaminergic pools.

An exploratory study consisting of physiochemical and animal experiments was undertaken with the objective of developing one or more metal-L-DOPA chelate systems for an improved transport of L-DOPA into the brain. This approach is based on a theoretical speculation that the pyridoxal-dependent decarboxylation of L-DOPA in the precerebral areas might be obviated by an appropriate metal chelation of the aminocarboxylate end of the L-DOPA molecule. Equilibium studies on the interactions of L-DOPE with Cu2+,Zn2+, Co2+, Mg2+ and Fe2+ ions and their ATP chelates were carried out in order to examine the conditions for the selective binding of the terminal amine group. Metal chelate systems for in vivo transport experiments were selected viz., Cu2+ or Zn2+-L-DOPA (1:2) and Cu2+ or Zn2+-ATP-L-DOPA (1:1:1) which contained the amine-bound metal ion in a completely coordinated form. Results of in vivo studies involving the intraperitoneal administration of 14C-and 3H-LABELED L-DOPA compounds have shown a 100-150% increase in the transport of L-DOPA into the brain by using the Cu2+ and Zn2+ chelates over that effected by using the unchelated L-DOPA. A chromatographic analysis of the brain homogenates showed that only 6% of the overall radioactivity of the brain could be attributed to 3-methoxytyrosine, and the remaining activity was due to DOPA, dopamine and norepinephrine. The transport effectiveness was also compared with that obtained by using the combination drug, RO4-4602 + L-DOPA.

Coordination of biogenic amines with synaptosomal and vesicular metal ions: equilibrium and spectral studies in model systems.

Thermodynamic equilibrium studies using model systems were carried out on the nature and extent of coordination of twelve different biogenic amines and adenosine-5'-triphosphate (ATP) with the bivalent metal ions, viz., Ca2+ and Zn2+, which occur in the subcellular fractions of the brain, at 25.0 +/- 0.1 degrees C and at an ionic strength of 1.0 (KNO3). In the combined presence of the individual monoamines and ATP the metal ions were predominantly coordinated by ATP in the pH range 3.0 to 6.5 with binding constants (log KML) of 2.84 +/- 0.06 and 3.19 +/- 0.39 for the Ca2+ and Zn2+ chelates, respectively. Each of the monoamines coordinated with the metal-ATP chelate above pH 6. The stabilities of the chelates of some of the amines with Ca2+ -ATP (1:1) system were NE, 2.33 +/- 0.33; AA, 2.24 +/- 0.19; OA, 1.94 +/- 0.29; NMeN, 1.60 +/- 0.22; DA, 2.14 +/- 0.09. Values for the Zn2+-ATP-amine systems were: NE, 8.35 +/- 0.26; OA, 4.53 +/- 0.07; DA, 10.05 +/- 0.39. Absorption spectral studies were carried out in order to examine the nature of coordination of NE, DA, TA, and AA with Cu2+, Fe2+, and Mg2+ ions in the combined presence of ATP. Results of the spectral studies taken together with the (thermodynamic) equilibrium data have indicated that in the pH range of biological interest, the catechol amines (NE and DA) and ATP are both coordinated to the "synaptosomal and vesicular" metal ions. The results further indicated that both the pyrocatechol and the ethanolamine groups of NE might be involved in the coordination of Cu2+. However, the interaction of the ethanolamine group of the NE molecule with the rest of the metal ions was not indicated.

Inability of chronic alcoholics with liver disease to use food as a source of folates, thiamin and vitamin B6.

Absorption of folates, thiamin, vitamin B6, pantothenate and riboflavin from a natural food source--yeast--and their respective synthetic forms was studied in 37 patients with liver disease due to alcoholism, and 12 healthy, nonalcoholic subjects. All alcoholics absorbed riboflavin and pantothenate but had a significantly lowered absorption of thiamin and vitamin B6 from yeast. Alcoholics absorbed synthetic vitamin B6, but not thiamin. Ingested folylpolyglutamates (the predominant folates in yeast) could not serve as a source of folate for the alcoholics, but synthetic folylmonoglutamate served. We suggest that the folate, vitamin B6, and thiamin deficits so common in alcoholic liver disease ensue from inability to absorb these specific vitamins from foods.