Synthesis and characterization of polymer-supported calix[4]arenes and bifunctional ion-exchange resins for selective metal ion complexation

Bifunctional ion-exchange resins and polymer-supported calix[4]arenes have been synthesized and characterized. The ion-selectivity of these polymers was evaluated. Phosphonic acid polymers were synthesized from polystyrene beads at varying levels of crosslinking and studied for their ability to complex Eu(III) and Fe(III) from varying acid concentrations. The percent complexed decreased with increasing crosslinking and acid concentrations regardless of the type of support used. However, by introducing a hydrophilic sulfonic acid ligand into the polymer matrix, rapid kinetics was obtained even with a highly crosslinked gel from high ionic strength solutions due to increased accessibility. The principle of bifunctionality is thus proposed as an alternative to macroporosity for enhanced complexation kinetics. Complexation of metal ions through a mechanism of inter- and intra-ligand cooperation for enhanced ionic selectivities was evaluated. The diphosphonic acid resin, due to the possibility of intra-ligand cooperation of the phosphoryl groups, had high affinities for all metal ions studied especially in less acidic solutions. The dicarboxylic acid resin was ineffective at the pH studied due to protonation of the carbonyl oxygen. The complexation behavior of the phosphonoacetic acid resin was comparable to the monophosphoric acid resin, leading to the belief initially that cooperation of the phosphoryl-carbonyl groups was not possible by intra-ligand cooperation. However, the ability of a β-ketophosphonate resin to complex high amounts of Cd(II) from a 0.10 N HNO3 solution showed that they can in fact cooperate by an intra-ligand mechanism for enhanced affinities. Hydrogen bonding of the carboxylic acid proton to the phosphoryl oxygens was proposed as the reason for poor affinities displayed by the phosphonoacetic acid resin. Calix[4]arene and phosphorylated calbc[4]arene were successfully immobilized onto crosslinked polystyrene supports. The former was able to complex Cs(I) from a 1 N NaOH solution in amounts greater than 96% while the latter was effective in complexing transition metal ions fi om acidic solutions. The effective cooperation of the ligating groups arranged around the cavity was responsible for the high selectivities displayed by these resins

Theoretical Investigations of Structural and Magnetic Ground State Stability of BiMnO3

AbstractWe investigate the crystal structure and magnetic ground state of monoclinic BiMnO3 using first principles calculations, in order to shed some light on the long standing issues related to the structural stability and ferroelectric polarization of BiMnO3. Our total energy calculations based on full structural optimization reveals that BiMnO3 stabilizes to monoclinic C2/c (centrosymmetric) with ferromagnetic ground state. Furthermore, to validate model calculations report, in which antiferromagnetic ordering is assumed to co-exist with ferromagnetism, to drive ferroelectric polarization, we invoke antiferromagnetic ordering in our calculations and find that this ordering indeed breaks the inversion symmetry and induces ferroelectric polarization along x-z plane

Association between primary hypothyroidism and metabolic syndrome and the role of C reactive protein: a cross–sectional study from South India

<p>Abstract</p> <p>Background</p> <p>Hypothyroidism (sub-clinical and overt) and metabolic syndrome are recognized risk factors for atherosclerotic cardiovascular disease. This study is an effort to identify the proposed association between these two disease entities and the risk factors involved in this association.</p> <p>Methods</p> <p>A cross – sectional study from a tertiary care teaching hospital in Chennai city, South India. 420 patients with metabolic syndrome (NCEP – ATP III criteria) were included in the study group. 406 appropriately age and sex matched controls having no features of metabolic syndrome (0 out of the 5 criteria) were compared with the study group. The study extended over a 5 year period. TSH, FT4 were measured for both the groups using electrochemiluminescence immuno assay. HsCRP was measured for all the patients in the study group. The baseline characteristics between the groups were compared with Student's't' test. Chi-square test was used to analyze the association between metabolic syndrome and hypothyroidism (overt and sub-clinical). Logistic regression analysis was applied to identify the association between hypothyroidism and the patient characteristics in the study group.</p> <p>Results</p> <p>Of the 420 patients in the study group, 240 were females (57.1%), 180 were males (42.9%) with mean age 51 ± 9.4 years. Of the 406 patients in the control group, 216 were females (53.2%), 190 males (46.8%) with mean age 49 ± 11.2 years. In the study group, 92 had sub-clinical hypothyroidism (SCH) (21.9%), 31 were overtly hypothyroid (7.4%) and 297 were euthyroid (70.7%). In the control group 27 patients had sub-clinical hypothyroidism (6.6%), 9 patients had overt hypothyroidism (2.2%) and 370 patients were euthyroid (91.2%). On comparison SCH (P < 0.001) and overt hypothyroidism (P < 0.001) were significantly associated with the study group as compared to the control group. Logistic regression analysis recognized the association between female gender (P = 0.021) and HsCRP (P = 0.014) with sub-clinical hypothyroidism and female gender (P = 0.01) with overt hypothyroidism in the study group.</p> <p>Conclusion</p> <p>Hypothyroidism is associated with metabolic syndrome and females are more at risk. Metabolic syndrome patients with a raised HsCRP are at significant risk of having sub-clinical hypothyroidism.</p

Enhancement of gastrointestinal absorption of poorly water soluble drugs <i>via </i>lipid based systems

1056-1065Development of knowledge on lipids has attracted the scientific community for the effective utilization of the natural and synthetic lipids. Bioavailability of poorly water soluble drugs from gastrointestinal tract (GIT) can be enhanced by formulating the drugs in lipid based formulations. This formulation can increase the dissolution of poorly water soluble drugs, and facilitates the format ion of solubilized phases from which absorption may occur. The enhanced solubility of lipophilic drugs from lipid-based systems will not necessarily arise directly from the administered lipid, but most likely from the intra luminal processing to which they are subjected prior to absorption. This review will focus on assessment of lipid-based formulations of drugs with a consideration of how gastrointestinal physiology, the choice of lipids and their formulation attribute and the mode of lipid digestion in the GLT influence the bioavailability of lipophilic drugs

A modified cell design for the quantitative evaluation of vapour phase corrosion inhibhitors

A modified cell design was fabricated to evaluate the vapour phase corrosion inhibitors (VPI) in the powdery 8.<; well as liquid/oily forms by continuous condensation test metJlod. llsing this experimental set-up, problems associated with the condensation of water vapour on the inhibitor, which reduces the volatility caD be eliminated and more reliable quantitative weight loss results can be obtained. The modified method was used in the evaluation of I:l series of compounds as VPI and it was found that the results were quite reproducible and comparable with visual observation

Design, synthesis and H1-antihistaminic activity of novel 1-substituted-4-(3-chlorophenyl)-[1,2,4] triazolo [4,3-a] quinazolin-5(4H)-ones

In the present study a series of 1-substituted-4-(3-chlorophenyl)-[1,2,4] triazolo [4,3-a] quinazolin-5(4H)-ones were synthesized and screened for their H1-antihistaminic activity. The synthesized compounds were characterized by IR, 1H-NMR, mass spectral data and purity of the compounds was determined by elemental analysis. Antihistaminic activity of the title compounds was evaluated by histamine induced bronchoconstriction method in guinea pigs. Among the series, 4-(3-chlorophenyl)-1-methyl-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-one (S5) was the most potent with the percentage protection of 69.65% and its potency is comparable to the reference drug chlorpheniramine maleate (70.09% protection). Interestingly the sedative property of compound S5 was found to be negligible (5.36%) when compared to chlorpheniramine maleate (34.92%)