Differential protonation and dynamic structure of doxylamine succinate in solution using 1H and 13C NMR

A protonation and dynamic structural study of doxylamine succinate, a 1:1 salt of succinic acid with dimethyl-[2-(1-phenyl-1-pyridin-2-yl-ethoxy)ethyl]amine, in solution using one- and two-dimensional 1H and 13C NMR experiments at variable temperature and concentration is presented. The two acidic protons of the salt doxylamine succinate are in 'intermediate' exchange at room temperature, as evidenced by the appearance of a broad signal. This signal evolves into two distinct signals below about -30 degrees C. A two-dimensional 1H-1H double quantum filtered correlation experiment carried out at -55 degrees C shows protonation of one of the acidic protons to the dimethylamine nitrogen. A two-dimensional rotating frame 1H-1H NOE experiment at the same temperature reveals that the other proton remains with the succinate moiety. Comparison of the 1H and 13C chemical shifts and the 13C T1 relaxation times of the salt with those of the free base further substantiate the findings.     

Miscibility and Thermal Behavior of Pullulan/Polyacrylamide Blends

Blends of Pullulan (PU) and Polyacrylamide (PAM) having biomedical applications were prepared and characterized in order to evaluate the miscibility of natural component with the synthetic one. Blends with different composition ratios were prepared using water as common solvent. Viscosity, ultrasonic velocity and density were measured at 30 and 40°C. Furthermore, the blend films were prepared by a solution casting method and analyzed by DSC, FTIR and TGA methods. Results of ultrasonic and density methods revealed the semi-miscibility of the blend. Using viscosity data, interaction parameters (Chee's ‘μ’ and Sun's ‘α’) were computed. The values confirmed that the blend is miscible when the Pullulan content is less than 20% in the blend. Change in temperature had no effect on the miscibility nature of the blends. Intermolecular interactions of hydrogen bonding type were confirmed by DSC and FTIR methods. Thermal behavior of blends was investigated using TGA method.     

Nernst effect and diamagnetism in phase fluctuating superconductors

We study superconducting systems in the regime where superconductivity is destroyed by phase fluctuations. We find that the Nernst effect has a much sharper temperature decay than predicted by Gaussian fluctuations, with an onset temperature that tracks Tc rather than the pairing temperature. We find a close quantitative connection with diamagnetism--the ratio of magnetization to transverse thermoelectric conductivity reaches a fixed value at high temperatures. We interpret measurements on underdoped cuprates in terms of a dilute vortex liquid over a wide temperature range above Tc.     

Bio-detoxification of Phorbol Esters and Other Anti-nutrients of Jatropha curcas Seed Cake by Fungal Cultures Using Solid-State Fermentation

Jatropha seed cake, a byproduct after biodiesel extraction, has several anti-nutrients and toxins. Solid-state fermentation was carried out for the detoxification of the Jatropha seed cake (JSC) using different fungal cultures. The reduction in the anti-nutritional components such as tannins, phytates, saponins, lectin and protease inhibitor, and phorbol esters on 6th, 9th, and 12th day of fermentation was analyzed. The phorbol ester content in the unfermented JSC was 0.83 mg/g, and the maximum degradation of phorbol esters to the extent of 75 % was observed in the case of JSC fermented with Cunninghamella echinulata CJS-90. The phytate degradation in the fermented JSC was in the range of 65–96 %. There was a gradual reduction of saponin content in the JSC from 6th to 12th day, and the reduction of saponin was in the range of 55–99 % after solid-state fermentation. The trypsin inhibitor activity and lectin were 1,680 trypsin inhibitor units (TIU) per gram and 0.32 hemagglutinating unit in the unfermented JSC, respectively. Trypsin inhibitor activity and lectin could not be detected in JSC after 12th day of solid-state fermentation. Tannins accounted for 0.53 % in unfermented JSC, and there was a marginal increase of tannins after solid-state fermentation. The results indicate that biological detoxification could be a promising method to reduce anti-nutritional compounds and toxins in the JSC.     

Design and Activity of Novel Oxadiazole Based Compounds That Target Poly(ADP-ribose) Polymerase

Novel PARP inhibitors with selective mode-of-action have been approved for clinical use. Herein, oxadiazole based ligands that are predicted to target PARP-1 have been synthesized and screened for the loss of cell viability in mammary carcinoma cells, wherein seven compounds were observed to possess significant IC₅₀ values in the range of 1.4 to 25 µM. Furthermore, compound 5u, inhibited the viability of MCF-7 cells with an IC₅₀ value of 1.4µM, when compared to Olaparib (IC₅₀ = 3.2 µM). Compound 5s also decreased cell viability in MCF-7 and MDA-MB-231 cells with IC₅₀ values of 15.3 and 19.2 µM, respectively. Treatment of MCF-7 cells with compounds 5u and 5s produced PARP cleavage, H2AX phosphorylation and CASPASE-3 activation comparable to that observed with Olaparib. Compounds 5u and 5s also decreased foci-formation and 3D Matrigel growth of MCF-7 cells equivalent to or greater than that observed with Olaparib. Finally, in silico analysis demonstrated binding of compound 5s towardsthe catalytic site of PARP-1, indicating that these novel oxadiazoles synthesized herein may serve as exemplars for the development of new therapeutics in cancer.     

Polystyrene Microspheres in Tissue-Simulating Phantoms Can Collisionally Quench Fluorescence

Tissue-simulating phantoms that replicate intrinsic optical properties in a controlled manner are useful for quantitative studies of photon transport in turbid biological media. In such phantoms, polystyrene microspheres are often used to simulate tissue optical scattering. Here, we report that using polystyrene microspheres in fluorescent tissue-simulating phantoms can reduce fluorophore quantum yield via collisional quenching. Fluorescence lifetime spectroscopy was employed to characterize quenching in phantoms consisting of a fluorescein dye and polystyrene microspheres (scattering coefficients _s 100-600cm^–1). For this range of tissue-simulating phantoms, analysis using the Stern-Volmer equation revealed that collisional quenching by polystyrene microspheres accounted for a decrease in fluorescence intensity of 6-17% relative to the intrinsic intensity value when no microspheres (quenchers) were present. The intensity decrease from quenching is independent of additional, anticipated losses arising from optical scattering associated with the microspheres. These results suggest that quantitative fluorescence measurements in studies employing such phantoms may be influenced by collisional quenching.     

Computation of stacking and twin faults in varieties of cotton fibers using whole powder pattern fitting technique

The extent of stacking and twin faults has been estimated in different varieties of cotton fibers grown in the Karnataka State of India using wide-angle X-ray scattering (WAXS) data. Further, the microstructural parameters such as crystal size 〈N〉 and lattice strain (g in %) have been determined by a whole powder pattern fitting technique developed by us. In all these cases we note that the stacking and twin faults are quite significant in determining the properties of cotton fibers and their microstructural parameters.     

Entanglement entropy of critical spin liquids

Quantum spin liquids are phases of matter whose internal structure is not captured by a local order parameter. Particularly intriguing are critical spin liquids, where strongly interacting excitations control low energy properties. Here we calculate their bipartite entanglement entropy that characterizes their quantum structure. In particular we calculate the Renyi entropy S(2) on model wave functions obtained by Gutzwiller projection of a Fermi sea. Although the wave functions are not sign positive, S(2) can be calculated on relatively large systems (>324 spins) using the variational Monte Carlo technique. On the triangular lattice we find that entanglement entropy of the projected Fermi sea state violates the boundary law, with S(2) enhanced by a logarithmic factor. This is an unusual result for a bosonic wave function reflecting the presence of emergent fermions. These techniques can be extended to study a wide class of other phases.