Separation of nucleoside monophosphates using preferential anion exchange intercalation in layered double hydroxides

We report the first example of selective intercalation of nucleoside monophosphates in a layered host material. The intercalated nucleoside monophosphates can then be quantitatively recovered from the inorganic host and so this opens up the possibility of using simple layered inorganic hosts as rapid, cost effective and recyclable materials for the purification and separation of complex biomolecules.     

Spectrophotometric determination of molybdenum based on charge transfer complex in PVA medium

A very simple, selective and sensitive method was developed for the spectrophotometric determination of Mo in the presence of W. The method was based on the formation of color charge transfer complex, molybdotungstophosphate-3,3',5,5'-tetramethylbezidine anion, which was solubilized and stabilized in PVA medium. Following the recommended procedure, molybdenum could be determined in the linear range of 0.04-2.5 mug ml(-1) and the molar absorptivity was 1.47x10(4) l mol(-1) cm(-1) at 660 nm. The proposed method had been applied to the determination of trace molybdenum in tungsten ore with satisfactory results.     

石墨烯负载高活性Pd催化剂对乙醇的电催化氧化

以石墨粉为原料, 采用Hummers法液相氧化合成了氧化石墨(GO), 然后用化学一步还原制得石墨烯负载钯催化剂. X射线衍射(XRD)、透射电镜(TEM)表征表明, Pd在石墨烯载体上有较好的分散度, 粒径为3-5 nm. 电化学活性面积(EASA)、循环伏安(CV)、计时电流(CA)和计时电位(CP)等电化学测试表明, 与传统Pd/Vulcan XC-72相比, Pd/石墨烯催化剂对碱性介质中乙醇电催化氧化的催化活性有了很大的提高.     

多糖凝胶的孔径和化学结构对单壁碳纳米管流动性和选择性分离的影响

基于凝胶柱色谱分离技术研究了单分散的单壁碳纳米管（SWCNTs）在不同化学结构多孔多糖凝胶中的流动特性以及对金属型（m-）/半导体型（s-）SWCNTs 分离的影响. 通过比较SWCNTs 在一系列不同孔径的葡聚糖Sephacryl 凝胶中的流动行为,发现减小孔径尺寸能够增强s-SWCNTs 与凝胶之间的吸附作用力,使大直径的m-SWCNTs 快速地流过凝胶颗粒,而选择性地保留了小直径的s-SWCNTs. 进一步发现多糖凝胶化学结构比孔径尺寸在SWCNTs 的m/s 分离中起着更重要的作用. 当基于葡聚糖结构的Sephacryl 凝胶中的氨基结构被琼脂糖结构所取代时,如Superdex 200 和Sepharose 2B凝胶会增强它们与SWCNTs 之间的作用力,使SWCNTs 的保留时间延长,降低了s-SWCNTs 的选择性和纯度. 此外,即使拥有与Sephacryl S100类似的孔径范围,当Sephacryl 凝胶中的氨基被疏水环氧丙烷基团取代时,葡聚糖凝胶Sephadex G100 与SWCNTs 的作用力很弱,导致所有SWCNTs 快速流动,无法实现SWCNTs 的m/s 分离. 因而,我们认为凝胶孔径和化学结构共同影响并调控了SWCNTs的m/s分离的选择性、纯度以及分离效率.     

Photoelectron spectra of metal-containing molecules with resolutions better than 1 meV

This article describes the applications of zero electron kinetic energy, ZEKE, photoelectron technique to metal-containing molecules. Examples include vanadium dimer, metal trimer compounds (Nb₃O, Nb₃C₂, Nb₃N₂, Zr₃O, and Y₃C₂), and metal atom-molecule complexes (InNH₃, AlNH₃, ZrO(CH₃)₂, and YO(CH₃)₂). The bond length of vanadium dimer cation has been determined from the rotationally resolved spectra with a resolution of 1.5 cm⁻¹, or 0.19 meV. The geometric conformations and electronic states of the clusters and complexes have been identified by combining the vibrationally resolved spectra and Franck–Condon factor calculations. The vibrational spectra have linewidths of 4–8 cm⁻¹.     

Hydrolysis of platinum(II) phosphine complexes in aqueous 1.0 M NaNO3 medium

Hydrolysis of [Pt(PR₃)₂]²⁺ (R=Me, Et) have been investigated at 25.0°C in 1.000 M NaNO₃ by the combined emf–NMR method. Quantitative analysis of the emf and ³¹P NMR data revealed the formation of [{Pt(PR₃)₂(μ-OH)}₂]²⁺ as the only hydrolysis product in the range 1.5<−log h<5.7. Least-squares calculation gave log β_Me=−4.19±0.04 and log β_Et=−3.58±0.04, where β_Me and β_Et stand for the formation constants of the dimeric cations of methyl and ethyl derivatives, respectively. The ¹⁹⁵Pt NMR data were also consistent with this model.     

Development of ionomer membranes for fuel cells

In this contribution an overview is given about the state-of-the-art at the membrane development for proton-conductive polymer (composite) membranes for the application membrane fuel cells, focusing on the membrane developments in this field performed at ICVT.For preparation of the polymers, processes have been developed for sulfonated arylene main-chain polymers as well as for arylene main-chain polymers containing basic N-containing groups, including a lithiation step. Covalently cross-linked polymer membranes have been prepared by alkylation of the sulfinate groups of sulfinate group-containing polymers with α,ω-dihalogenoalkanes. The advantage of the covalently cross-linked ionomer membranes was their dimensional stability even at temperatures of 80–90°C, their main disadvantage their brittleness when drying out, caused by the inflexible covalent network. Sulfonated and basic N-containing polymers (commercial polymers as well as self-developed ones) have been combined to acid–base blends containing ionic cross-links. The main advantage of these membrane type was its flexibility even when dried-out, its good to excellent thermal stability, and the numerous possibilities to combine acidic and basic polymers to blend membranes having fine-tuned properties. The main disadvantage of this membrane type was the insufficient dimension stability at T>70–90°C, caused by breakage of the ionic cross-links, where the ionic cross-links broke as easier as lower the basicity of the polymeric base was. Some of the acid–base blend membranes were applied to H₂ membrane fuel cells and to direct methanol fuel cells up to 100°C, yielding the result that these membranes show very good perspectives in the membrane fuel cell application.     

Application of vacuum ultraviolet laser-induced breakdown spectrometry for steel analysis — comparison with spark-optical emission spectrometry figures of merit

Laser induced breakdown spectrometry (LIBS) was evaluated for trace analysis in steel in comparison to spark discharge optical emission spectrometry (spark-OES), including low C, N and S (<100 ppm) concentrations. The development of an industrial prototype is described, with the ability to be able to use either a spark or a laser source on the same optical mounting to directly compare the performances of both sources. Similar sensitivities between LIBS and spark-OES could be obtained for low alloying elements (Mn, Cr, Ni, Mo, etc., in the range of 0–1200 ppm) as well as for traces of C, N, S, P between 2 and 100 ppm. Limits of detection as low as 5 ppm were measured in a reproducible way for C, P, and S, whereas lower N signal stabilities result in 20 ppm LOD. Compared to a spark source used on the same optical mounting, it should be possible to improve these figures by a factor of 3. The results presented in this work lead us to believe that LIBS should rapidly develop as a steel control tool, and the instrumentation built up will be suitable for on-site process control applications.