Measurement of storage time, estimation of ion number and study of absorption line profile in a Paul trap

Europium (Eu⁺) ions were confined in a Paul trap and detected by non-destructive method. Storage time of Eu⁺ ions achieved in vacuum was improved by orders of magnitude employing buffer gas cooling. The experimentally detected signal was fitted to the ion response signal and the total number of ions trapped was estimated. It is found that the peak signal amplitude as well as the product of FWHM and the peak signal amplitude is proportional to the total number of trapped ions. The trapped ion secular frequency was swept at different rates and its effect on the absorption line profile was studied both experimentally and theoretically.     

Correction: Dermatan sulfate in tunicate phylogeny: Order-specific sulfation pattern and the effect of [→4IdoA(2-Sulfate)β-1→3GalNAc(4-Sulfate)β-1→] motifs in dermatan sulfate on heparin cofactor II activity

After the publication of the work entitled "Dermatan sulfate in tunicate phylogeny: Order-specific sulfation pattern and the effect of [→4IdoA(2-Sulfate)β-1→3GalNAc(4-Sulfate)β-1→] motifs in dermatan sulfate on heparin cofactor II activity", by Kozlowski et al., BMC Biochemistry 2011, 12:29, we found that the legends to Figures 2 to 5 contain serious mistakes that compromise the comprehension of the work. This correction article contains the correct text of the legends to Figures 2 to 5.     

Branched polyether with multiple primary hydroxyl groups: polymerization of 3-ethyl-3-hydroxymethyloxetane

Cationic polymerization of 3-ethyl-3-hydroxymethyloxetane gives branched, soluble macromolecules with multiple glycolic end groups. There are approximately 3–4 “normal” units per one branched unit.     

Polyethers containing stable ionic end-groups

Polyethers of low and medium molecular weight containing at both ends stable ionic groups (phosphonium ions) were obtained by living cationic polymerization of tetrahydrofuran initiated by difunctional initiator, trifluoromethanesulfonic anhydride, followed by termination with triphenylphosphine. It was shown, that products contain significant quantities of low molecular weight diphosphonium salt; a plausible explanation is presented. Alternative approach to the synthesis of diionically terminated polyethers was based on the conversion of hydroxyl end-groups of polyether diols, which can be obtained by cationic Activated Monomer (AM) polymerization of e.g. oxiranes, into phosphonium ion end-groups. Using this approach, poly(ethylene oxide)'s with M_n ranging from 300 to 3400, terminated at both ends with stable ionic groups, were prepared and characterized. Measurements of NMR relaxation times and viscosity measurements provide the evidence for the aggregation of ionic end-groups. The potential applications of inter- and intramolecular aggregation are discussed. It is shown, that intramolecular aggregation of ionic terminal groups in low molecular weight poly(ethylene oxide) leads to cyclic structures resembling crown ethers and showing comparable efficiency for complexing cations.     

Mercury transformations in chemical agent simulant as characterized by X-ray absorption fine spectroscopy

Chemical analyses of U.S. stockpiled mustard chemical warfare agent show some agent destined for destruction contains mercury [L. Ember, Chem. Eng. News 82 (2004) 8]. Because of its toxicity, mercury must be removed from agent prior to incineration or be scrubbed from incineration exhaust to prevent release into the atmosphere. Understanding mercury/agent interactions is critical if either atmospheric or aqueous treatment processes are used. We investigate and compare the state of mercury in water to that in thiodiglycol, a mustard simulant, as co-contaminants are introduced. The effects of sodium hypochlorite and sodium hydroxide, common neutralization chemicals, on mercury in water and simulant with and without co-contaminants present are examined using X-ray absorption fine spectroscopy (XAFS).     

Polyepichlorohydrin diols free of cyclics: Synthesis and characterization

Polymerization of epichlorohydrin (ECH) in the presence of diols, catalyzed by Lewis or protic acids, proceeds by activated monomer mechanism (AMM), i.e., by subsequent additions of protonated monomer molecules to the terminal hydroxyl groups of the growing chain. As opposed to the typical active chain end mechanism, side reactions, including cyclization, are strongly suppressed in the polymerization by AMM and well-defined linear product are obtained. It follows from kinetic considerations, that in order to achieve the high contribution of AMM, the reaction should be carried out at low instantaneous concentration of monomer, and this can be accomplished by slowly adding ECH to the reaction mixture. Using this approach, polyepichlorophydrin diols have been prepared in the M?_n ～ 2500 products with DP _n = [M]₀/[I]₀ can be obtained practically free of cyclic by-products with the yields approaching quantitative. Polyepichlorohydrin diols obtained by AM polymerization are strictly bifunctional, regular head-to-tail polymers containing mainly (≥ 95%) secondary hydroxyl and groups.