Preparation of a bipolar membrane by photografting polymerization

A single-sheet bipolar membrane was synthesized via photografting polymerization of an acrylic acid cation exchange layer onto the surface of a commercial homogeneous anion exchange membrane with benzophenone (BP) as the main initiator, diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide (TPO) and 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) as coinitiators and divinylbenzene (DVB) or neopentylene glycol diacrylate (NPGDA) as crosslinking agent. It was found that when benzophenone was used as single initiator and the crosslink agent is absent, the grafting degree (D _g) increases with the prolongation of irradiation time. The grafting degree reaches a maximum at 60 seconds reaction time when the crosslinking agent is added, and the grafting degree is higher when using NPGDA instead of DVB as crosslinking agent. The grafting degree increases as the composite initiator system is used. When polymerization was initiated by BP and TPO, and the dosage of NPGDA was 2.5% mol concentration of monomer, the grafting degree reaches 30.1%. __________ Translated from Journal of Beijing Technology and Business University, 2007, 25(1): 15–18 [译自: 北京工商大学学报]     

Diastereoselective synthesis of polyfunctional compounds based on the tandem sequence of threeAdE reactions using cyclic vinyl ethers as first alkene components

The reaction of the bicyclic thiophanium ions salts, generated by the sequential interaction ofp-TolSCI with dihydropyran or 1-methoxycycloalkene and then with an acyclic alkyl vinyl ether in the presence of a Lewis acid and with silicon- or tin-capped π-donors, proceeds with high diastereoselectivity at all newly created chiral centers. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 82–94, January, 2000.     

Conductometric and microcalorimetric analysis of the alkaline-earth/alkali-metal ion exchange onto polyacrylic acid

The specificity of the exchange between divalent (Di²⁺ = Ca²⁺ or Ba²⁺) and monovalent (M⁺ = Li⁺, Na⁺ or K⁺) ions onto a polyacrylic chain is examined using conductometric and microcalorimetric techniques. Assuming the formation of a bidentate complex between the Di²⁺ and the carboxylate groups, the conductometric data give the exchange ratio (Di²⁺/M⁺) and the speciation of the acrylic groups. No significant difference is observed between the three alkali-metal ions for a given Di²⁺ ion. Comparisons between Ca²⁺ and Ba²⁺ show a stronger hydrophobicity of the former as it precipitates at a complexation ratio r = 0.33 versus r = 0.45 for the Ba²⁺ salt. Microcalorimetric data show that all Di²⁺/M⁺ exchange energies are positive and depend significantly on the type of cations. The largest displacement energy (the more positive) is found for the binding of Ca²⁺ with sodium polyacrylate (8.13 kJ · mol⁻¹) and the smallest for Ba²⁺ with lithium polyacrylate (1.88 kJ · mol⁻¹). The interpretation of the data leads to the conclusion that specificity of the Di²⁺ binding originates in the dehydration phenomenon and specificity between the three alkali-metal ions is due to the decrease in the electrostatic bond strength with an increase in the ionic radii. The Di²⁺/M⁺ exchange is entropically driven. Received: 28 January 1999 Accepted in revised form: 7 April 1999     

Mechanism of the reduction of molecular nitrogen to hydrazine by niobium (iii) hydroxide

The effect of the concentration of water on the rate of reduction of molecular nitrogen to hydrazine by niobium(iii) hydroxide in alkaline H₂O−MeOH and D₂O−MeOD mixtures was studied. In both cases, the reaction rate is maximum when [H₂O]=4 mol L⁻¹, and the inverse isotopic effect (K ^D/k ^H>1) is observed when [H₂O]<20 mol L⁻¹. Similar regularity was observed for the reaction of hydrogen elimination. It was found that HD is formed in the H₂O−MeOH system in the presence of D₂. The conclusion was made that the ratedetermining stage in hydrazine formation is the transfer of a hydride ion to the dinitrogen molecule coordinated to the binuclear Nb^III center. A kinetic scheme satisfactorily explaining the effect of the concentration of water ([H₂O]=1.5−49.0 mol L⁻¹) on the reaction rate constant was proposed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1600–1604, September, 1997.     

基于苯并噻唑Zn2+荧光探针及其细胞造影应用

设计合成基于苯并噻唑Zn²⁺荧光增强型探针BHP,在HEPES缓冲液中测其对Zn²⁺识别性能。实验结果表明,BHP对Zn²⁺有较高的选择性,对其他金属离子如Cd²⁺,Fe²⁺,Ni²⁺,Pb²⁺,Hg²⁺,Al³⁺,Mn²⁺,Ag⁺,Cu²⁺,Co²⁺,Na⁺,K⁺,Mg²⁺和Ca²⁺无明显荧光增强响应。BHP与Zn²⁺按1：1计量比配位,在生理条件下荧光强度不受pH值影响。在HeLa细胞中对Zn²⁺的造影表明BHP可用于生物体Zn²⁺检测。     

Ion Association and Hydration in Aqueous Solutions of Nickel(II) and Cobalt(II) Sulfate

Aqueous solutions of nickel(II) and cobalt(II) sulfate have been investigated at 25 ^∘C by dielectric relaxation spectroscopy (DRS) over a wide range of frequencies (0.2 ≤ ν (GHz) ≤ 89) and salt concentrations (0.025 ≤ c(mol-L⁻¹) ≤ 1.4). The spectra indicate, as for MgSO₄(aq) studied previously, the simultaneous presence of double solvent-separated, solvent-shared and contact ion pairs in both NiSO₄(aq) and CoSO₄(aq). The stepwise formation constants for each ion-pair type and the overall association constant, obtained from the data are in good agreement with ultrasonic relaxation and other estimates. The DR spectra at higher concentrations (c ≥ 0.5 mol-L⁻¹) suggest the existence of a nonlinear triple ion M₂SO₄²⁺(aq). Consistent with the very strong hydration of the salts, which have ‘effective’ hydration numbers approaching 27 at infinite dilution, there are no significant differences in any of the relaxation or thermodynamic parameters for NiSO₄(aq) and CoSO₄(aq), except that the triple ion appears to be somewhat more stable for the latter.     

Recent advances in layered LiNi x CoyMn1−x−y O2 cathode materials for lithium ion batteries

Lithium cobalt oxide, LiCoO₂, has been the most widely used cathode material in commercial lithium ion batteries. Nevertheless, cobalt has economic and environmental problems that leave the door open to exploit alternative cathode materials, among which LiNi _x Co_yMn_{1 − x − y} O₂ may have improved performances, such as thermal stability, due to the synergistic effect of the three ions. Recently, intensive effort has been directed towards the development of LiNi _x Co _y Mn_{1 − x − y} O₂ as a possible replacement for LiCoO₂. Recent advances in layered LiNi _x Co_yMn_{1 − x − y} O₂ cathode materials are summarized in this paper. The preparation and the performance are reviewed, and the future promising cathode materials are also prospected.     

Thermodynamic and kinetic properties of scandium (I) ion reacting with SCO in gas phase

Theoretical studies on the thermodynamic and kinetic properties of the reactions of scandium (I) ion with the sulfur-transfer reagent SCO via the C-O bond activation pathway have been carried out over the temperature range of 200-1200 K using the DFT/B3LYP method, general statistical thermodynamics, and Eyring transition state theory with Wigner correction. The relevant reactions include reaction 1 ¹Sc⁺ + SCO → ¹IM1 → ¹TS1 → ¹IM2 (Step 1) → ¹TS2 → ¹IM3 → ¹ScO⁺ + ¹CS (Step 2), and reaction 2 ³Sc⁺ + SCO → ³IM1 → CP → ¹IM2 → ¹TS2 → ¹IM3 → ¹ScO⁺ +¹CS in which the spin multiplicity changes from the triplet state to the singlet state in the crossing region. It was concluded that the order of the equilibrium constants (K) and the reaction rate constants (k) are consistent with that of their corresponding exoergic energies, ΔE, and reaction barriers, respectively. Step 2 of reaction 1 is both thermodynamically and kinetically favored over the whole temperature range. Moreover, both Reaction 1 and reaction 2 are exothermic and spontaneous processes in which their entropy increases, and the magnitudes of their thermodynamic values all decrease with increasing temperature.      

Theoretical study on decomposition of γ-halo allylalkoxide and β-halo acrylate ions

β, γ-Substituted γ-halo allylalkoxide ions decompose to form a halogen ion, formaldehyde, and an alkyne under mild conditions, for example at room temperature. The E isomer does not differ from the Z isomer in terms of activation energy. We attempted to shed light on the mechanism of the reaction by using ab initio molecular orbital calculations. The observed propensity was confirmed by the present calculation on model molecules, γ-chloro allylalkoxide ions. We conducted further calculations and compared the alkoxide results with a similar reaction of β-haloacrylate ions that release carbon dioxide instead of formaldehyde. This similar reaction needs heating as high as 150°C. The activation energy of the acrylate ions (36–39 kcal mol⁻¹) was calculated to be about 10 kcal mol⁻¹ higher than that of the alkoxide ions. The activation energy of the E acrylate ion is smaller by 0.8 kcal mol⁻¹ than that of the Z isomer at the MP2/6-31+G**//RHF/6-31+G* level of theory. This is consistent with experimental results. While the ready deprotonation from the carboxylic group does not activate the acrylate ion very much, the alkoxide ion is destabilized to a great degree in the process of anion formation. The difficulty in deprotonation that proceeds from the neutral molecule is seen in the difference in the activation energies for the decomposition of the corresponding anions. Therefore, the pK _a of a hydroxy or a carboxylic group plays the leading role in determining the magnitude of activation energies of allyl halides with a negatively charged fragment. Received: 2 July 1998 / Accepted: 9 September 1998 / Published online: 8 February 1999     

The effect of β-CD polymers structure on the efficiency of copper(II) ion flotation

β-Cyclodextrin (β-CD) polymers were prepared by cross-linking of β-CD with phtalic and 3-nitrophtalic anhydride in anhydrous N,N-dimethylformamide (DMF) in the presence of NaH. The weight-average molecular weight (M _W) and the chemical structure of the polymers were determined using high performance size exclusion chromatography (HPSEC) with refractive index (RI) detector, and ¹H NMR spectroscopy. The molecular weight of the polymer increased with molar ratio of substrates and reaction temperature. ¹H NMR spectra revealed that the β-CD polymers contained both mono- and diesters of phtalic and 3-nitrophtalic acids. In the case of phtalic moieties about four or five diester moieties groups and for 3-nitrophtalic moieties about to or three diester moieties are linkages for β-CD molecule, respectively. Results of copper(II) flotation obtained with the use of nonylphenol polyoxyethyl glycol ether as an non-anionic surfactant and β-CD polymers as complexation collector agent, show␣that the removal of Cu²⁺ decreases with increase of molecular mass of β-CD polymers linked by phtalic or␣3-nitrophtalic anhydrides. For both derivatives with pH increase the copper(II) removal increase. The highest flotation removal, i.e. 93%, was found for β-CD polymers synthesized at 100 °C with molar ratio CD:NaH:3-nitrophtalic anhydride equal to 1:7:7.     

N-苯基-1,7-二硒杂-4-氮杂[7]二茂铁环蕃的合成、晶体结构及其光电性质研究

合成了N-苯基-1,7-二硒杂-4-氮杂-[7]二茂铁环蕃(1),并用核磁、质谱、单晶X-射线衍射进行了表征。晶体结构测试结果表明1是属于正交晶系的Ibca空间群,晶胞参数a=0.954 74(2)nm,b=0.959 58(2)nm,c=7.859 0(2)nm,其中晶胞参数c值很长,这种现象在N-Se杂大环中很少见。光谱研究显示1仅对Hg2+和Cu2+的加入产生响应,表现为紫外最大吸收峰的红移和荧光淬灭。     

Morphological studies of the mechanism of pit growth of pure aluminum in sulfate ion- or nitrate ion-containing 0.1 M NaCl solutions

The mechanism of pit growth of pure aluminum (Al) in sulfate ion (SO₄ ^2–)- or nitrate ion (NO₃ ^–)-containing 0.1 M sodium chloride solutions has been studied in terms of the morphological changes of artificial pits using potentiodynamic polarization experiment, potentiostatic current transient technique and optical microscopy. The increase in SO₄ ^2– and NO₃ ^– ion concentrations in NaCl solution raised the pitting potential E _pit of pure Al, which is ascribed to the impediment to pit initiation on pure Al by the addition of SO₄ ^2– or NO₃ ^– ions. From the potentiostatic current transients of artificial pits in aqueous 0.1 M NaCl solution, the average value of the pit current was observed to increase with increasing SO₄ ^2– ion concentration, whereas that value of the pit current in the presence of NO₃ ^– ions increased up to ca. 0.4 M NO₃ ^– ion concentration and then decreased abruptly with increasing NO₃ ^– ion concentration. From observations of the morphologies of the pits, it appears that the pit grows preferentially in the lateral direction or in the downward direction by adding SO₄ ^2– or NO₃ ^– ions to aqueous 0.1 M NaCl solution, respectively. Based upon the experimental results, two different pit growth mechanisms by anion additives can be proposed: (1) pit growth by the preferential attack of both SO₄ ^2– and Cl^– to the pit wall in SO₄ ^2–-containing solutions; (2) pit growth by the creation of an aggressive environment at the pit bottom up to 0.4 M NO₃ ^– ion concentration due to the lower mobility of NO₃ ^– than Cl^– in NO₃ ^–-containing solutions. Electronic Publication     

Phase composition, electroconductivity, oxygen ion transport number, and microhardness of Ln1 ? xSrxGa0.5 ? y/2Al0.5 ? y/2MgyO3 ? δ (Ln = La, Pr, Nd; x, y = 0.10, 0.15)

Phase composition, electroconductivity, oxygen ion transport number, and microhardness of samples of Ln_{1 − x} Sr_xGa_{0.5 − y/2}Al_{0.5 − y/2}Mg_yO_{3 − δ} (Ln = La, Pr, Nd; x, y = 0.10, 0.15) synthesized by a ceramic methods are studied. Methods of x-ray diffraction analysis and scanning electron microscopy reveal the La-containing samples to be homogeneous and have a perovskite structure. Magnesium does not dissolve in Pr-and Nd-containing systems but forms an individual phase based on magnesium oxide. Apart from magnesium oxide, in these systems there form extrinsic phases, specifically, LnSrGa₃O₇ and an unknown phase. The electroconductivity of La_{1 − x} Sr_xGa_{1 − y} Mg_yO_{3 − δ} decreases after substituting Al for Ga. Ceramic La_{1 − x} Sr_xGa_{0.5 − y/2}Al_{0.5 − y/2}Mg_yO_3−δ is a purely ionic conductor in the temperature interval 500 to 1000°C; Nd_xSr_xGa_{0.5 − y/2}Al_{0.5 − y/2}Mg_yO_{3 − δ} has predominantly ionic conduction; and the predominant type of conduction in Pr_{1 − x} Sr_xGa_{0.5 − y/2}Al_{0.5 − y/2}Mg_yO_{3 − δ} is electronic below 700–800°C, with the contribution of ionic conduction increasing at higher temperatures. Substituting Al for Ga raises the hardness of ceramics under study. Among the compositions studied, La_0.85Sr_0.15Ga_0.45Al_0.45Mg_0.10O_{3 − δ} and La_0.85Sr_0.15Ga_0.425Al_0.425Mg_0.15O_{3 − δ} exhibit a combination of electroconductivity and hardness that is optimal for application as electrolyte at reduced temperatures (600–800°C). The Pr_{1 − x} Sr_xGa_{0.5 − y/2}Al_{0.5 − y/2}Mg_yO_{3 − δ} system possesses mixed ionic-electronic conduction and high hardness, which makes it appealing for application as oxygen-penetrable membranes. Original Russian Text ? Yu.V. Danilov, A.D. Neuimin, L.A. Dunyushkina, L.A. Kuz’mina, N.S. Zybko, Z.S. Martem’yanova, A.A. Pankratov, 2007, published in Elektrokhimiya, 2007, Vol. 43, No. 1, pp. 57–65.     

N-苯基-1,7-二硒杂-4-氮杂[7]二茂铁环蕃的合成、晶体结构及其光电性质研究

合成了N-苯基-1,7-二硒杂-4-氮杂-[7]二茂铁环蕃（1）,并用核磁、质谱、单晶X-射线衍射进行了表征。晶体结构测试结果表明1是属于正交晶系的Ibca空间群,晶胞参数a=0.95474（2）nm,b=0.95958（2）nm,c=7.8590（2）nm,其中晶胞参数c值在N-Se杂大环中很少见。光谱研究显示1仅对Hg²⁺和Cu²⁺的加入产生响应,表现为紫外最大吸收峰的红移和荧光淬灭。     

荧光素/层状钇氢氧化物复合体的发光性能及对Hg2+的识别

合成了层状钇氢氧化物(LYH)复合体FN/OS-LYH(FN为荧光素,OS为1-辛烷磺酸钠),研究了复合体的光致发光性能及剥离态胶体对Hg~(2+)的荧光识别性能。固态下,FN的钠盐不发光,FN/OS-LYH复合体发射黄绿光(564 nm);甲酰胺中,剥离为胶体悬浮液后,复合体发射绿光(540 nm,即剥离后蓝移24 nm),比FN阴离子的发射(572 nm)蓝移32 nm。复合体对高毒性Hg~(2+)具有很好的荧光识别能力,优于其他离子(Mg~(2+),Ni~(2+),Co~(2+),Cu~(2+),Zn~(2+),Pb~(2+)和Cd~(2+))。复合体加入Hg~(2+)后发生荧光淬灭,Hg~(2+)检测限为2.73×10-7mol·L-1,淬灭常数(Ksv)为4.82×102 L·mol-1。     

硫化铜空心纳米球的融硫修饰及其对水中Hg^2+的高选择性吸附富集

通过简单便捷的方法合成出了单质硫改性的CuS空心球纳米材料(CuS@S HSs),并研究了该材料对水中典型重金属污染物Hg^2+的吸附富集性能及机理。研究结果表明,当硫的投料质量比值(wS/wCuS))为30%时,CuS@S HSs对Hg^2+的吸附量高达1207mg·g^-1,较未负载单质硫时提高了229%。CuS@S HSs可以在15 min内将水中超过99%的Hg^2+富集分离。最重要的是,在多种重金属离子(Pb^2+、Ni^2+、Cd^2+、Cr^3+)共存的情况下,CuS@S HSs对Hg^2+表现出优异的单一选择吸附性。     

Evaluation and interlaboratory validation of a GC-MS method for analysis of pesticide residues in teas

A method was described for simultaneous determination of nine organic heterocyclic pesticide residues by gas chromatography-mass spectrometry-selected ion monitoring. Atrazine, vinclozolin, procymidone, triflumizole, imazalil, buprofezin, propiconazole, fenarimol, and pyridaben were clearly separated from each other, extracted with acetone—hexane mixture, purified with graphitized carbon black cartridge and neutral Al₂O₃ cartridge, eluted with acetone—hexane mixture, simultaneously determined by GC-MS, and then quantified with an external standard method. Recoveries of pesticides ranged from 73 % to 116 % at the spiked level of 0.01–30 mg kg⁻¹, while the relative standard deviation was between 3 % and 27 %. In addition, the limits of determination (0.01 mg kg⁻¹ to 5.0 mg kg⁻¹) and linearity (0.02–40 μg mL⁻¹) revealed that simultaneous determination of multi-residues in Chinese teas (like Oolong tea, green tea, red tea, etc.) was possible. Furthermore, an interlaboratory study among 5 labs was conducted to further validate the method, and the results were satisfactory.     

Trace Analysis by Heavy Ion Induced X-Ray Emission

 Various K-, L- and M-shell X-ray production cross sections are measured for heavy ion impact on elements in the range Z ₂ = 13 to 83. The ion species range from Z ₁ = 10 to 36, and ion energies from 1 to 16 MeV are used. Enhanced cross sections are observed when the projectile K- or L- binding energy is similar to the energy of the target K-, L- or M-shell. This effect is used to improve the analysis sensitivity for selected elements. As an example trace analysis of Fe in glass with V, Mn, Co and Ni ions is investigated. Results are compared with proton induced X-ray emission analysis on the same samples. In these samples Fe-K_α X-ray production is similar for irradiation with 3 MeV protons and 14 MeV Ni ions. However the signal to background ratio is four times higher for the irradiation with Ni ions as compared to irradiation with protons. Advantages and drawbacks of heavy ion induced X-ray emission for quantitative analysis compared to proton induced X-ray emission analysis are discussed.     

一种基于DPA识别基团的可视化检测锌离子的荧光增强型探针

以N,N-二(2-吡啶甲基)胺(DPA)为识别基团,设计合成了一种用于检测Zn2+的荧光增强型探针WN,在CH3CH2OH/TrisHCl(1∶9,V/V,pH=7.4)缓冲溶液中研究了它对Zn2+的识别特性。实验结果表明,WN对Zn2+有较高的选择性和灵敏度,它们之间的结合比为1∶1,对Zn2+的检出限为1.14×10-8 mol·L-1。WN能够快速地可视化检测Zn2+,在HeLa活细胞中对Zn2+的荧光显微成像表明WN可应用于生物体的检测。     

A rhodamine-based Hg2+-selective fluorescent probe in aqueous solution

A new rhodamine-based Hg²⁺-selective fluorescent probe (I) was designed and synthesized. Compound I displays excellent selective and sensitive response to Hg²⁺ over other transition metal ions in neutral aqueous solutions. I itself is a colorless, nonfluorescent compound. Upon addition of Hg²⁺ to its solution, the thiosemicarbazide moiety of I undergoes an irreversible desulfurization reaction to form the corresponding 1,3,4-oxadiazole (II), a colorful and fluorescent product, causing instantaneous development of visible color and strong fluorescence emission. Based on this mechanism, a fluorogenic probe for Hg²⁺ was developed. The fluorescence increases linearly with the Hg²⁺ concentration up to 0.8 μmol L⁻¹ with the detection limit of 9.4 nmol L⁻ (3σ).