Phosphonobetaine/sulfur dioxide copolymer by Butler’s cyclopolymerization process

The zwitterionic monomer, ethyl 3-(N,N-diallylammonio)propanephosphonate and sulfur dioxide were cyclocopolymerized in DMSO using azobisisobutyronitrile or ammonium persulfate as initiators to afford a pH-responsive polyphosphonobetaine/SO₂ (PPB/SO₂) copolymer. The polymers, on treatment with HCl and NaOH, gave the aqueous solutions of the corresponding cationic polyphosphononic acid (CPP) and anionic polyphosphonate (APP). The solution properties of the PPB having two pH-responsive functionalities were investigated in detail by potentiometric and viscometric techniques. Basicity constants of the amine and phosphonate groups in APP were found to be “apparent” and as such follow the modified Henderson–Hasselbalch equation. The incorporation of SO₂ moiety has resulted in the decrease of basicity constant of the nitrogens in the copolymer by staggering ?2 units of log K in compare to that of the corresponding homopolymer. The basicity difference is expected to have an effect on the chelating properties of the polymers. In contrast to many polycarbo- and -sulfobetaines, the PPB was all found to be soluble in salt-free water as well as in salt (including Ca²⁺ and Li⁺)-added solutions. The PPB demonstrated ‘antipolyelectrolyte’ viscosity behavior and found to have higher viscosity values in LiCl than in NaCl or NaI.     

湖北网湖^137Cs、^210Pb计年与沉积速率研究

采用放射性核素^137Cs和^210Pb计年法测定百年来湖北网湖沉积物的年代，据此计算出网湖的沉积速率．结果表明：2种计年方法测得的沉积速率基本一致，以1954年和1963年为时标，^137Cs测得的沉积速率分别为0．594cm·a^-1和0．557cm·a^-1。^210Pb计年法CIC模式计算得到网湖平均沉积速率为0．56cm·a^-1．CRS模式得到百年来网湖沉积速率变化较大，20世纪50年代以前，平均沉积速率为0．2cm·a^-1左右；50年代至80年代中期，平均沉积速率上了一个台阶，约为0．4cm·a^-1；80年代中期以后平均沉积速率攀升至约0．6cm·a^-1，网湖沉积速率变化与湖区自然环境的改变和人类活动的影响密切相关．     

Non-isothermal thermoanalytical studies on the salt roasting of chalcopyrite using KCl

In an earlier study [1], the isothermal kinetics of salt roasting of chalcopyrite under an oxidizing atmosphere using KCl was studied in the temperature range 523–773 K. The salt roasting reaction was found to be chemically controlled at temperatures below 600 K both under static air and oxygen atmosphere. At higher temperatures, the process was not thermally activated because of a change in the chemistry of the process. In the present study, the salt roasting of chalcopyrite using KCl under oxygen and static air atmosphere was studied by non-isothermal thermoanalytical studies up to 723 K. The effect of salt content, heating rate and particle size on the salt roasting behavior was studied using TG/DTA techniques at a programmed linear heating rate. The TG and DTA studies reveal two distinct chemical processes, one operative up to 620 K and the other from 620 to 723 K. The integral method of Coats and Redfern was used for the treatment of non-isothermal kinetic data. The non-isothermal analysis confirmed the chemical control mechanism at temperatures below 620 K. However, the activation energy for the process derived from non-isothermal thermogravimetric analysis is almost twice as that deduced from isothermal measurements. In the temperature range 620–723 K, the kinetic data still obeys the interfacial reaction control model although the activation energy in this temperature range is very low.     

Thermodynamic properties and phase diagrams of fluoride salts for nuclear applications

This work is a critical review of the chemical-physical properties of the fluoride salts of interest in the Molten Salt Reactor project. In total five salt compositions are discussed. Two of them are choices for coolant applications (based on LiF-BeF₂ and NaF-NaBF₄ systems) one is considered as a heat transfer salt (LiF-NaF-KF system) whereas the other two are the main candidates for the fuels in non-moderated breeder and thermal breeder reactors, respectively (LiF-ThF₄ and LiF-BeF₂-ThF₄ systems). For all the systems the phase diagrams are presented with the emphasis on the melting behaviour and the vapour pressure. Heat capacity, density, viscosity and thermal conductivity, as well as the solubility for actinides in case of the fuels are presented also.     

Swelling of poly(ethylene oxide) gel in aqueous solutions of sodium dodecyl sulfate with added sodium chloride

The swelling behavior of poly(ethylene oxide) (PEO) gels in aqueous solutions of sodium dodecyl sulfate (SDS) with and without NaCl was investigated. In the absence of NaCl, PEO gels with different degrees of cross-linking began to swell from a concentration lower than the critical micelle concentration (cmc) of SDS, then showed sigmoidal enhancements of swelling in a higher SDS concentration region until the degrees of swelling reached maximum values. The SDS concentration at which the swelling began to appear was in reasonable agreement with the critical aggregation concentration (cac) value reported for the aqueous PEO system. For the cases where NaCl was present, the swelling behavior of PEO gel was different from that when NaCl was absent in the following way. The concentrations where the swelling begins to appear, and hence those where the degree of swelling rises steeply, decreased with an increase in NaCl concentration. The ultimate degrees of swelling at higher concentration regions also decreased with an increase in the NaCl concentration. The lowering of the SDS concentrations at which the PEO gel began to swell is in line with the decreases in the cmc of SDS solutions containing NaCl and also with the decreases in the cac of PEO solution. Electronic Publication     

Ionic liquid salt bridge based on tributyl(2-methoxyethyl)phosphonium bis(pentafluoroethanesulfonyl)amide for stable liquid junction potentials in highly diluted aqueous electrolyte solutions

A moderately hydrophobic ionic liquid, tributyl(2-methoxyethyl)phosphonium bis(pentafluoroethanesulfonyl)amide ([TBMOEP⁺][C₂C₂N⁻]), shows a very stable liquid junction potential upon contact with an aqueous solution whose ionic strength is as low as 1 μmol dm⁻³. The stability with the maximum excursion of the potential within ±0.5 mV for 30 min is very promising for accurate determination of pH and other single ion activities potentiometrically.     

分光光度法测定食盐中的碘

采用分光光度法对食盐中碘含量进行定量分析.对反应条件进行试验及优化,得最佳测定条件为:测定波长565nm,0.5mol/L盐酸2.00mL、3%双氧水3.00mL、10g/L淀粉1.00mL,显色时间10min.在此条件下测得碘含量为29.32mg/kg,符合国家标准.本方法操作简便,可靠,重现性好,专属性强,具有广泛...     

Improved sensitivity of headspace gas chromatography for organic aromatic compounds

Summary The effect of adding an electrolyte and increasing the temperature on the preconcentration of volatile compounds in headspace analysis has been investigated. Quantification of the interactive effects of temperature and addition of salt on the vapor concentration is of interest for the determination of trace organic impurities in pharmaceutical base materials. This study was undertaken to investigate the quantitative effects of the addition of salts alcohols, and acetone, and of increasing the temperature on the vapor concentrations and distribution coefficients of volatile aromatic compounds (benzene, toluene, ando-xylene). It was found that the concentration of aromatic compound residues in the headspace could be increased by adding an inert salt to the water, but this effect was not very significant because of the low orginal solubility of the aromatic compounds in water. The reverse effect can be achieved by use of polar organic additives; this can be explained by the high polarizability of aromatic compounds and their greater solubility in the presence of these solvents. Presented at Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 1–3, 1999.     

东疆北部地区小冰期环境特征的湖相沉积记录

本文根据新疆东疆北部巴里坤湖湖相沉积的孢粉及地球化学元素含量分析，运用因子分析法处理数据，恢复了巴里坤地区近５００年来的环境演变序列。广泛的区域性对比表明，所获结果具较高可信度，故本文不但获得了在新疆地区由湖相沉积所揭示的小冰期以来的环境演变信息，另一方面丰富了本地区短时代环境演变研究的方法和手段。     

Microwire Chronoamperometric Determination of Concentration,Diffusivity, and Salinity for Simultaneous Oxygen and Proton Reduction

A microwire chronoamperometric method is reported employing a 25 µm diameter platinum microwire for multi‐parameter electroanalysis with digital simulation‐based evaluation (employing DigiElch 4.F). Concentration and diffusion coefficient data are obtained for the reduction of oxygen and for the reduction of protons individually and simultaneously in saline (0.1 M to 4.0 M NaCl) electrolyte media. The diffusion coefficient and concentration data for oxygen allows salinity levels to be estimated. The microwire chronoamperometry method offers versatility and precision due to (i) a slow approach to steady state (when compared to microdisc methods) and (ii) insignificant viscosity effects (when compared to hydrodynamic methods).