Characterization of the solvation environment provided by dilute aqueous solutions of novel siloxane polysoaps using the fluorescence probe pyrene

Solubilization environment afforded by several of the novel allyl glycidyl ether-modified methylhydrosiloxane polymers are investigated using a common polycyclic aromatic hydrocarbon fluorescence probe, pyrene. The backbone of the polymer has been modified by the addition of an alkyl chain of varying length (either C8, C12, or C18) and to differing degrees of substitution. The nomenclature adopted for the purposes of these studies is as follows: "AGENT" represents the backbone polymer with no alkyl substitution, and "OAGENT", "DAGENT", and "SAGENT" are substituted with n-octyl, n-dodecyl, and n-octadecyl, respectively. The percentage of alkyl substitution is designated as 10, 15, and 20%. The pyrene polarity scale (defined as the ratio of the intensity of peak I to peak III) was used to determine the relative dipolarity of the cybotactic region provided by approximately 1 w/w% aqueous polymer solutions compared to 10 mM sodium dodecylsulfate (SDS) micellar solution. Results indicate that 10-15% DAGENT afforded the most hydrophobic solubilization site, followed by 15% OAGENT and 15% SAGENT. In addition, as the degree of alkyl substitution of DAGENT increased from 10 to 20%, the cybotactic region appeared to become more hydrophobic. Furthermore, a deeper investigation into the relative size of the solubilization site revealed that all alkyl-substituted polymers promoted excimer formation at relatively low pyrene concentrations, indicating the possibility of localized concentration enhancement within the solvation pockets and/or compartmentalization of the solute molecules. The pyrene fluorescence excitation data strongly indicates ground-state heterogeneity that is most prominent in AGENT and decreases as the alkyl chain length is increased. This provides a relative sense of the size and shape of the solvation pockets afforded by each polymer solution. An overall analysis of the collected data indicated that these alkyl-substituted polymers may provide a more selective and efficient pseudostationary phase in electrokinetic chromatography with better solvation capacity for hydrophobic compounds compared to SDS.     

Application of gamma-ray spectrometry for the assay of uranium in crude UF4—An input material used for producing nuclear grade U-metal at the natural uranium conversion plants

A -spectrometric method has been developed for the assay of uranium in crude UF₄, which is used as a secondary source of input material for producing nuclear grade U-metal at natural uranium conversion plants. The method makes use of a NaI (Tl) detector coupled with a multichannel analyzer. The 1 MeV -ray of²³⁸U is used for calibration. A method for the fabrication of uniform -assay calibration standards is also suggested, based on the results of this investigation. The calibration standards were prepared by soaking the matrix in uranium solution and then drying the whole material. The amount of²³⁸U in the crude UF₄ sample was directly estimated by comparing the areas under the 1 MeV -ray peak of known calibration standards with the corresponding areas of the samples to be measured. 100 g each of the standard and the sample were counted. 5 crude UF₄ samples were analyzed by this method. The uranium contents in these samples were found to be in the range of 12.2–28.7 g. To compare the -ray spectrometry results with a completely independent method, chemical analysis by potentiometry of all the samples was also done. The -spectrometric results were found to agree within ±18% with the chemical analysis results.     

Correlation between the fluorescent response of microfluidity probes and the water content and viscosity of ionic liquid and water mixtures

Accurate data on transport properties such as viscosity are essential in plant and process design involving ionic liquids. In this study, we determined the absolute viscosity of the ionic liquid + water system at water mole fractions from 0 to 0.25 for three 1-alkyl-3-methylimidazolium ionic liquids: 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide and 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide. In each case, the excimer to monomer ratio for 1,m-bis(1-pyrenyl)alkanes (m= 3 or 10) was found to increase linearly with the mole fraction of water. Of the probes studied only PRODAN and rhodamine 6G, both of which have the ability to participate in hydrogen bonding, exhibited Perrin hydrodynamic behavior in the lower viscosity bis(trifluoromethane sulfonyl)imides. As a result, these probes allow for the extrapolation of the absolute viscosity of the ionic liquid mixture from the experimental fluorescence steady-state polarization values.     

Some new organotin(IV), aluminium(III)-μ-oxoisopropoxides and their benzoylacetone derivatives

The first organotin(IV), aluminium(III)-μ-oxoisoprovides of the type [R₃SnOA](OⁱPr)₂] (R = Me or Ph) have been made by heating of trimethyl- or triphenyl-tin acetate with aluminium isopropoxide. The reactions of these μ-oxoisopropoxides with benzoylacetone in 1:1 and 1:2 molar ratios yielded the compounds of the type [R₃SnOAl(OⁱPr)(bzac)] and [R₃SnOAl(bzac)₂] (where R = Me or Ph and BZAC = deprotonated benzoylacetone), respectively.     

<Superscript>90</Superscript>Y-DOTA-Lanreotide: A potential agent for targeted therapy

Several human tumors such as neuroendocrine tumors, medullary thyroid carcinoma, etc., express somatostatin receptors which specifically bind somatostatin and its analogues such as lanreotide, octreotide, etc. In order to prepare a therapeutic agent for targeting such tumors, attempts were made to prepare ⁹⁰Y-DOTA-Lanreotide. Lanreotide could be successfully conjugated with the macrocyclic chelating agent DOTA (1,4,7,10-tetraaza cyclododecane tetracetic acid) which forms stable complexes with ⁹⁰Y. ⁹⁰Y-DOTA-Lanreotide could be prepared in >98% radiochemical purity and remained stable for 72 hours at room temperature. The tracer showed specific binding to A431 cells. Biodistribution studies in C57BL6 mice bearing melanoma showed ∼1.3% uptake pergram of tumor at 24-hour p.i.     

2,4,5-Tribromo-1H-imidazole in the egg masses of three muricid molluscs

From analysis by gas chromatography/mass spectrometry (GC/MS), the presence of either 2,4,5-tribromo-1H-imidazole (1) or 3,4,5-tribromo-1H-pyrazole (2) was tentatively identified in lipophilic extracts from the egg masses of three muricid molluscs. Synthesis of these compounds, followed by comparison of the GC retention times and fragmentation patterns from electron impact MS, with those of the natural products, indicated that it was 2,4,5-tribromo-1H-imidazole rather than the pyrazole. This imidazole is likely to be responsible for some of the antimicrobial activity observed in the egg extracts. This is the first report of this compound from a natural source.     

Anion mediated polytype selectivity among the basic salts of Co(II)

Basic salts of Co(II) crystallize in the rhombohedral structure. Two different polytypes, 3R₁ and 3R₂, with distinct stacking sequences of the metal hydroxide slabs, are possible within the rhombohedral structure. These polytypes are generated by simple translation of successive layers by (2/3, 1/3, z) or (1/3, 2/3, z). The symmetry of the anion and the mode of coordination influences polytype selection. Cobalt hydroxynitrate crystallizes in the structure of the 3R₂ polytype while the hydroxytartarate, hydroxychloride and α-cobalt hydroxide crystallize in the structure of the 3R₁ polytype. Cobalt hydroxysulfate is turbostratically disordered. The turbostratic disorder is a direct consequence of the mismatch between the crystallographically defined interlayer sites generated within the crystal and the tetrahedral symmetry of the SO₄²⁻ ions.     

On the analysis of mercuric nitrate in flue gas by GC-MS

Recent research has demonstrated that in a simulated flue gas stream containing NO(2) and SO(2) elemental mercury is initially captured on a carbon or manganese oxide sorbent. After approximately an hour, however, mercury breaks through relatively rapidly, and the volatile form of mercury emitted is an oxidized species. The volatile mercury species emitted from a granular MnO(2) sorbent was trapped in an impinger containing cold acetonitrile. Subsequent evaporation of 95% of the acetonitrile in a Kuderna-Danish apparatus and gas chromatography (GC) of the concentrate resulted in a single mercury-containing GC peak at 5.5 min; the retention time and mass spectrum of this compound matched exactly those of a standard mercury(II) nitrate hydrate, Hg(NO(3))(2).H(2)O dissolved in acetonitrile. The volatile mercury component analyzed from injection of this standard solution was shown to be a form of methylmercury that is produced in the GC column by reaction of the highly reactive mercury nitrate with the methylsiloxane GC phase. Because the on-column derivatization reaction seems to be unique to mercury nitrate, the GC-MS (gas chromatography-mass spectroscopic) analysis provides strong evidence for identification of the trapped oxidized mercury species as mercury nitrate although, because the nitrate becomes detached from the mercury atom in the on-column reaction, the identity is not proven.     

Synthesis and antispasmodic activity evaluation of bis-(papaverine) analogues

A new series of N-substituted bis-(tetrahydropapaverine) ring systems have been synthesised in expectation of better antispasmodic activity in comparison with papaverine. The synthesis of the targeted heterocycles is described along with a discussion of their structure activity relationship. The general synthetic methods of bis-(tetrahydropapaverine) analogues involve tetrahydropapaverine, various piperazines, diisocyanates and diisothiocyanates as starting materials. Pharmacological evaluation involves the in vitro antispasmodic activity on a freshly removed guinea pig ileum using a force displacement transducer amplifier connected to a physiograph. Among the analogues synthesized in the present study, N,N'-bis-[2-carbamoyl-1-(3,4-dimethoxybenzyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolinyl]piperazine (22), was found to be the most potent muscle relaxant (IC(50): 0.31 microM).     

Synthesis and characterisation of copolymers containing geraniol and styrene initiated by benzoyl peroxide

Alternating copolymer(s) containing geraniol and styrene sequences have been synthesized by using benzoyl peroxide as initiator in xylene at 80 °C. The copolymerisation follows ideal kinetics. The formation of the copolymer is confirmed by the presence of peaks at 7-7.5δ due to the phenyl group and 7-7.7δ due to the alcoholic group and 2900 cm⁻¹ due to the phenyl groups in the FTIR spectrum of the copolymer. The values of r₁(Sty)=0.76 and r₂(Ger)=0.03, calculated by the Kelen-Tüdos method, indicates some alternating nature of the copolymer. The glass transition temperature (T_g) found by differential scanning calorimetry, is 90 °C. The Alfrey-price Q-e parameters for geraniol are 0.221 and 0.649.