Efficient Site-Specific Incorporation of Thioamides into Peptides on a Solid Support

Designing bioactive peptides containing “thioamide” functionality to modulate their pharmacological properties has been thwarted so far because of various synthetic challenges. The fast, efficient, and inexpensive synthesis and incorporation of a wide range of thionated amino acids into a growing peptide chain on a solid support is reported using standard Fmoc-based chemistry. The commonly employed methodology is comprehensively investigated and optimized with significant improvements regarding the quantity of reagents and reaction conditions. The utility of the protocol is further demonstrated in the synthesis of dithionated linear and monothionated cyclic peptides, which has been a daunting task

Exploring Cyclopentadienone Antiaromaticity: Charge Density Studies of Various Tetracyclones

A systematic study of six tetracyclones has been carried out using experimental and theoretical charge density analysis. A three pronged approach based on quantum theory of atoms in molecules (QTAIM), nucleus independent chemical shifts (NICS) criterion, and source function (SF) contributions has been performed to establish the degree of antiaromaticity of the central five-membered ring in all the derivatives. Electrostatic potentials mapped on the isodensity surface show that electron withdrawing substituents turn both C and O atoms of the carbonyl group more electropositive while retaining the direction of polarity

Exploring Cyclopentadienone Antiaromaticity: Charge Density Studies of Various Tetracyclones

A systematic study of six tetracyclones has been carried out using experimental and theoretical charge density analysis. A three pronged approach based on quantum theory of atoms in molecules (QTAIM), nucleus independent chemical shifts (NICS) criterion, and source function (SF) contributions has been performed to establish the degree of antiaromaticity of the central five-membered ring in all the derivatives. Electrostatic potentials mapped on the isodensity surface show that electron withdrawing substituents turn both C and O atoms of the carbonyl group more electropositive while retaining the direction of polarity

Exploring Cyclopentadienone Antiaromaticity: Charge Density Studies of Various Tetracyclones

A systematic study of six tetracyclones has been carried out using experimental and theoretical charge density analysis. A three pronged approach based on quantum theory of atoms in molecules (QTAIM), nucleus independent chemical shifts (NICS) criterion, and source function (SF) contributions has been performed to establish the degree of antiaromaticity of the central five-membered ring in all the derivatives. Electrostatic potentials mapped on the isodensity surface show that electron withdrawing substituents turn both C and O atoms of the carbonyl group more electropositive while retaining the direction of polarity

Experimental Study on Chromium Containment by Admixed Soil Liner

Chrome tanneries generate large quantities of chromium-laden sludge that require proper disposal in engineered landfills to prevent contamination of subsurface soils and groundwater and reduce the risk to public health and the environment. This study investigates the feasibility of using a fine-grained soil as a suitable landfill liner material for the effective containment of chromium in the sludge leachate. Several series of laboratory permeability, adsorption, and column tests were conducted using soil without and with selected additives (rice husk, bentonite, and fly ash) to determine permeability and adsorption and transport of chromium in the soil. Permeability tests showed that the field soil amended with 17% rice husk and 2% bentonite provides the desired hydraulic conductivity of 10(-7) cm/s (or less) to minimize the leachate migration into the surrounding subsurface environment. The rice husk and bentonite admixtures significantly reduced the hydraulic conductivity of the soil from 3 x 10(-7) to 2.8 x 10(-9) cm/s, and this admixture was further tested for its effect on the adsorption and transport of chromium in the soil. The batch kinetics and column tests results showed that the soil possesses relatively high chromium adsorption capacity under natural or slightly alkaline condition. The batch tests showed that the amendment marginally improved the chromium adsorptive capacity of the soil. The column tests showed a slight increase in breakthrough time due to the presence of the amendment. The inclined base column tests showed that a mildly inclined liner configuration has a marginal effect on the chromium attenuation in the soil. Overall, this study showed that soil amended with 17% rice husk and 2% bentonite significantly decreased the hydraulic conductivity of the soil and slightly increased the adsorption of chromium, and therefore, has the potential for usage as a landfill liner in a landfill system to contain chromium contaminatio