Novel Carboxylic Acid-Capped Silver Nanoparticles as Antimicrobial and Colorimetric Sensing Agents

The present work reports the synthesis, characterization, and antimicrobial activities of adipic acid-capped silver nanoparticles (AgNPs@AA) and their utilization for selective detection of Hg²⁺ ions in an aqueous solution. The AgNPs were synthesized by the reduction of Ag⁺ ions with NaBH₄ followed by capping with adipic acid. Characterization of as-synthesized AgNPs@AA was carried out by different techniques, including UV–Visible spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Dynamic Light Scattering (DLS), and zeta potential (ZP). In the UV–Vis absorption spectrum, the characteristic absorption band for AgNPs was observed at 404 nm. The hydrodynamic size of as-synthesized AgNPs was found to be 30 ± 5.0 nm. ZP values (−35.5 ± 2.4 mV) showed that NPs possessed a negative charge due to carboxylate ions and were electrostatically stabilized. The AgNPs show potential antimicrobial activity against clinically isolated pathogens. These AgNPs were found to be selectively interacting with Hg²⁺ in an aqueous solution at various concentrations. A calibration curve was constructed by plotting concentration as abscissa and absorbance ratio (A_Control − A_Hg/A_Control) as ordinate. The linear range and limit of detection (LOD) of Hg²⁺ were 0.6–1.6 μM and 0.12 μM, respectively. A rapid response time of 4 min was found for the detection of Hg²⁺ by the nano-probe. The effect of pH and temperature on the detection of Hg²⁺ was also investigated. The nano-probe was successfully applied for the detection of Hg²⁺ from tap and river water     

Highly Efficient Candlelight Organic Light-Emitting Diode with a Very Low Color Temperature

Low color temperature candlelight organic light-emitting diodes (LEDs) are human and environmentally friendly because of the absence of blue emission that might suppress at night the secretion of melatonin and damage retina upon long exposure. Herein, we demonstrated a lighting device incorporating a phenoxazine-based host material, 3,3-bis(phenoxazin-10-ylmethyl)oxetane (BPMO), with the use of orange-red and yellow phosphorescent dyes to mimic candlelight. The resultant BPMO-based simple structured candlelight organic LED device permitted a maximum exposure limit of 57,700 s, much longer than did a candle (2750 s) or an incandescent bulb (1100 s) at 100 lx. The resulting device showed a color temperature of 1690 K, which is significantly much lower than that of oil lamps (1800 K), candles (1900 K), or incandescent bulbs (2500 K). The device showed a melatonin suppression sensitivity of 1.33%, upon exposure for 1.5 h at night, which is 66% and 88% less than the candle and incandescent bulb, respectively. Its maximum power efficacy is 23.1 lm/W, current efficacy 22.4 cd/A, and external quantum efficiency 10.2%, all much higher than the CBP-based devices. These results encourage a scalable synthesis of novel host materials to design and manufacture high-efficiency candlelight organic LEDs.     

Synthesis, <Emphasis Type="Italic">β</Emphasis>-<Emphasis Type="Italic">Glucuronidase</Emphasis> Inhibition,and Molecular Docking Studies of 1,2,4-Triazole Hydrazones

A series of 1,2,4-triazole hydrazones 1–25 has been synthesized and characterized using different spectroscopic techniques including FT-IR, ¹H-NMR, and ESI MS spectrometry. The synthetic derivatives were evaluated for their β-glucuronidase enzyme inhibition properties. Among them, 17 compounds demonstrated potential inhibitory activity towards β-glucuronidase with IC₅₀ values ranging between 2.50 and 53.70 µM. Compounds 1 having IC₅₀?=?2.50?±?0.01 µM was found to be the most active compound of the series and showed remarkable activity and found to be far more potent than the standard d-saccharic acid 1,4-lactone (IC₅₀?=?48.4?±?1.25 µM). Furthermore, the possible binding interaction of active compounds was explored by in silico studies. These compounds can be used for anti-diabetic drug development process.     

Unusual conversion of substituted-3-formylchromones to 3-(5-phenyl-3H-[1,2,4]dithiazol-3-yl)chromen-4-ones: a facile and efficient route to novel 1,2,4-dithiazoles

Substituted 3-formylchromones react with 2-phenyl-4-dimethylamino-1-thia-3-azabuta-1,3-diene (4) or thio-benzamide (7) by heating their toluene solution in a sealed tube to give novel substituted 3-(5-phenyl-3H-[1,2,4]dithiazol-3-yl)chromen-4-ones (6a-e) in high yields.     

Design,Synthesis, and Biological Evaluation of Artificial Macrosphelides in the Search for New Apoptosis‐Inducing Agents

A drug of two halves : New artificial compounds composed of a macrosphelide core skeleton and an epothilone side chain were designed and synthesized. These compounds were more potent inducers of apoptosis than the parent natural‐type macrosphelides.

     

Existence of Different Structural Intermediates and Aggregates on the Folding Pathway of Ovalbumin

Structural modifications of ovalbumin in presence of different concentration of guanidine hydrochloride (Gdn HCl) and glucose were investigated by using intrinsic fluorescence, Fourier transform infra-red spectroscopy, circular dichroism and 8-anilino-1-naphthalene-sulphonic acid, to confirm that partially folded intermediates of ovalbumin lead to aggregation. The two partially folded intermediates of ovalbumin were observed one at 1 M Gdn HCl and another in the presence of 20 mM glucose at 3 M Gdn HCl. Both intermediates exist as compact states with altered intrinsic fluorescence, prominent β-sheet secondary structure and enhanced ANS binding. Ovalbumin in the presence of glucose required more concentration of Gdn HCl (3 M) to exist as an intermediate state than control (1 M). Such alpha-helix/beta-sheet transition of proteins is a crucial step in amyloidogenic diseases and represents an internal rearrangement of local contacts in an already folded protein. Further, incubation for 24 h resulted in the formation of aggregates as detected by thioflavin T-assay. On further increasing the concentration of glucose to 50 mM and incubation time for various days resulted in the formation of molten globule state of ovalbumin at 6th day. Later on, at 10th day advanced glycated end products were observed.     

Onset of power-law scaling behavior in idiotypic random and scale-free networks

We numerically study the dynamics of model immune networks with random and scale-free topologies. We observe that a memory state is reached when the antigen is attached to the most connected sites of the network, whereas a percolation state may occur when the antigen attaches to the less connected sites. For increasing values of the connectivity of the antibody directly binded to the antigen, its population converges exponentially to the asymptotic value of the memory state. On the other hand, the next-nearest populations evolve slowly as power-laws towards the virgin-like state.     

Indefinite Least Squares Problem with Quadratic Constraint and Its Condition Numbers

In this paper,we consider the indefinite least squares problem with quadratic constraint and its condition numbers.The conditions under which the problem has the unique solution are first presented.Then,the normwise,mixed,and componentwise condition numbers for solution and residual of this problem are derived.Numerical example is also provided to illustrate these results.     

Chemical characterisation and hepatoprotective potential of Cosmos sulphureus Cav. and Cosmos bipinnatus Cav.

This study was conducted to validate the hepatoprotective activity of Cosmos sulphureus and Cosmos bipinnatus. Aqua-methanolic extracts of both plants were evaluated for the presence of various phyto-constituents through HPLC. Different doses of both plant extracts were administered to rats for nine days. Standard control was silymarin 100 mg/kg. Paracetamol 1 gm/kg was administered 3 h post treatment on 9th day for induction of hepatotoxicity. Blood was collected for the evaluation of liver biochemical markers and livers were removed for histopathological evaluation 24 h post-paracetamol treatment. HPLC analysis revealed the presence of quercetin, gallic acid, caffeic acid and chlorogenic acid in both plant extracts. The extracts of both plants decreased the level of alanine aminotransaminase and total bilirubin significantly (p < 0.05), dose dependently and protected hepatocytes from paracetamol-induced hepatotoxicity. It can be concluded that both plants may possess hepatoprotective activity possibly due to the presence of quercetin and phenolic compounds.     

Extrusion reactions-VI

4-(4-Quinazolinylthio)-butan-2-one and 3-(4-quinazolinylthio) propiophenone (4, R = CH₃, C₆H₅) with POCl₃ give 3-(3-oxobutyl)-4(3$\text{H}$)-quinazolone and 3-(2-benzoylethyl)-4(3H)-quinazolone (7, R = CH₃, C₆H₅, X = O) via S → N rearrangement followed by

conversion. Non-protic heterocyclic thioamides undergo similar oxidation.