Influence of temperature on thermal properties of (Sm,Eu) VO3

The bulk modulus and thermal properties of orthovanadates SmVO₃ and EuVO₃ in the temperature range 5 K≤T≤300 K have been investigated using the Modified Rigid Ion Model (MRIM) by incorporating the effect of lattice distortions. The results on the specific heat, cohesive energy, molecular force constant, the reststrahlen frequency and the Gruneisen parameter following the temperature driven structural phase transitions are presented. Our results are in fair agreement with the available experimental data. The specific heat results can further be improved by including the spin and orbital ordering contributions to the specific heat.     

Polarization transfer solid-state NMR for studying surfactant phase behavior

The phase behavior of amphiphiles, e.g., lipids and surfactants, at low water content is of great interest for many technical and pharmaceutical applications. When put in contact with air having a moderate relative humidity, amphiphiles often exhibit coexistence between solid and liquid crystalline phases, making their complete characterization difficult. This study describes a (13)C solid-state NMR technique for the investigation of amphiphile phase behavior in the water-poor regime. While the (13)C chemical shift is an indicator of molecular conformation, the (13)C signal intensities obtained with the CP and INEPT polarization transfer schemes yield information on molecular dynamics. A theoretical analysis incorporating the effect of molecular segment reorientation, with the correlation time τ(c) and order parameter S, shows that INEPT is most efficient for mobile segments with τ(c) < 0.01 μs and S < 0.05, while CP yields maximal signal for rigid segments with τ(c) > 10 μs and/or S > 0.5 under typical solid-state NMR experimental conditions. For liquid crystalline phases, where τ(c) < 0.01 μs and 0 < S < 0.3, the observed CP and INEPT intensities serve as a gauge of S. The combination of information on molecular conformation and dynamics permits facile phase diagram determination for systems with solid crystalline, solid amorphous, anisotropic liquid crystalline, and isotropic liquid (crystalline) phases as demonstrated by experiments on a series of reference systems with known phase structure. Three solid phases (anhydrous crystal, dihydrate, gel), two anisotropic liquid crystalline phases (normal hexagonal, lamellar), and two isotropic liquid crystalline phases (micellar cubic, bicontinuous cubic) are identified in the temperature-composition phase diagram of the cetyltrimethylammonium succinate/water system. Replacing the succinate counterion with DNA prevents the formation of phases other than hexagonal and leads to a general increase of τ(c).     

Electrochemical impedance spectroscopic analysis of aluminum and gallium mixed matrix membranes

Journal of Solid State Electrochemistry - Mixed matrix membrane revolutionized the field of electrochemistry with its multiple applications as a solid electrolyte, actuator, sensor, and storage...     

Designing of multiwalled carbon nanotubes reinforced low density polyethylene nanocomposites for suppression of electromagnetic radiation

High aspect ratio multi-walled carbon nanotubes (MWCNTs) reinforced low density polyethylene (LDPE) composites were prepared by solvent casting followed by compression molding technique. Electromagnetic interference (EMI) shielding effectiveness (SE) of these composites was investigated in the frequency range of 12.4?C18 GHz (Ku-band) for the first time. The experimental results indicate that the EMI-SE of these composites is sensitive to the MWCNT loading. The average value of EMI-SE reaches 22.4 dB for 10 wt% MWCNT-LDPE composites, indicating the usefulness of this material for EMI shielding in the Ku-band. The main reason for improved SE has been attributed to significant improvement in the electrical conductivity of the composites by 20 orders of magnitude, i.e., from 10^?20 for pure LDPE to 0.63 S/cm for MWCNT-LDPE, which is three order of magnitude higher than the previous reports for MWCNT-LDPE composites. Differential scanning calorimetry of the MWCNT-LDPE composites showed around 37% improvement in the crystalline contents over pure LDPE samples which resulted into enhanced thermal stability of the composites. The thermal decomposition temperature of LDPE is shifted by 40 °C on addition of 5 wt% MWCNT. The studies therefore show that these composite can be used as light weight, thermally stable EMI shielding, and antistatic material.     

Thioglycosylated cationic porphyrins--convenient synthesis and photodynamic activity in vitro

A convenient and flexible synthesis of meso-tetraaryl porphyrins substituted with three thioglycosyl units, and also bearing one pyridyl substituent is reported. Quaternisation of the pyridine nitrogen with alkyl iodides gives access to a range of water soluble glycosyl cationic porphyrins. Screening for photodynamic activity against human colorectal adenocarcinoma cells (HT-29) indicates that all the glycosyl cationic porphyrins made in this way are active photosensitisers, but direct comparison with a cationic porphyrin bearing no sugar residues indicates an important role for these groups in reducing generalised `dark' toxicity.     

UV-absorption studies of interaction of karanjin and karanjachromene with ds. DNA: Evaluation of binding and antioxidant activity

Two flavonoids, karanjin (Kj) and karanjachromene (Kc) have been investigated spectrophotometrically for their mode of interactions with double stranded (ds)-DNA at blood (7.4) and stomach (4.7) pH and at human body temperature (37°C). Benesi-Hildebrand equation was used to evaluate the binding constants, K _b . Binding constants at both pH values and at body temperature showed stronger binding of both the flavonoids and formation of 1:1 flavonoid-DNA complex via intercalative mode. However, K _b values for karanjin were evaluated to be comparatively greater than karanjachromene at both pH values. The highest value of binding constant (1.32×10⁵ M^?1) for karanjin at blood pH (7.4) demonstrated its comparatively stronger binding and greater effectiveness at this pH. Standard Gibbs free energy changes (ΔG) of flavonoid-DNA complexes were calculated as negative values and indicative of spontaneity of their binding. Both flavonoids showed significant DNA protection activity.      

Quantum parameters based study of some heterocycles using density functional theory method: A comparative theoretical study

Density functional theory can envisage a vast assortment of molecular possessions such as molecular structures, vibrational frequencies, molecular energies, ionization energies, polar, electric and magnetic properties etc. The efficacy of this method relies on the study of electronic parameters to categorize the reactive sites to comprehend the plausible action of these scaffolds. Further it also facilitates the correlation between the structural characteristics of drug and their inhibition efficiency against infectious microorganisms. In light of the above facts, we have studied the structural parameters such as energy (total), variation of electron density over highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), charge distribution, absolute electronegativity (χ), softness/hardness (σ/ɳ) and fraction of electron transfer (ΔN) of some previously synthesized heterocycles.     

Identification of Potential Vaccine Candidates Against Streptococcus pneumoniae by Reverse Vaccinology Approach

In the past few decades, genome-based approaches have contributed significantly to vaccine development. Our aim was to identify the most conserved and immunogenic antigens of Streptococcus pneumoniae, which can be potential vaccine candidates in the future. BLASTn was done to identify the most conserved antigens. PSORTb 3.0.2 was run to predict the subcellular localization of the proteins. B cell epitope prediction was done for the immunogenicity testing. Finally, BLASTp was done for verifying the extent of similarity to human proteome to exclude the possibility of autoimmunity. Proteins failing to comply with the set parameters were filtered at each step. Based on the above criteria, out of the initial 22 pneumococcal proteins selected for screening, pavB and pullulanase were the most promising candidate proteins.     

Synthesis and Crystal Structure of (Z)-Ethyl 5-(phenylamino)-3-(phenylimino)-3H-1,2-dithiole-4-carboxylate

The compound (Z)-ethyl 5-(phenylamino)-3-(phenylimino)-3H-1,2-dithiole-4-carboxylate 3 has been synthesized by the reaction of ethylacetoacetate 1 and phenylisothiocyanate 2. Its structure has been established by ¹H NMR, ¹³C NMR, infrared, mass spectra, and x-ray crystallography.