Cobalt Determination by Means of Flow Injection On-line Sorbent Preconcentration-Flame Atomic Absorption Spectrometry with 1-Nitroso-2-naphthol as a Complexing Reagent

The suitability of 1-nitroso-2-naphthol(NN) as a complexing agent for on-line preconcentration of cobalt eluted on the C_(18) microcolumn by means of the FI-FAAS system was tested. Various parameters affecting the complex formation and its elution were optimized. A 2.3×10~(-3) mol/L reagent solution and the aqueous sample solution acidified with 0.1％ (volume fraction) nitric acid were on-line mixed (6.4 mL/min) on a reaction coil set at (65±1)℃ and flowed through the microcolumn for 30 s. The pH of the mixed solution was adjusted to 3—4 with HNO_3(1 mol/L) or NaOH(1 mol/L). The adsorbed complexes in the microcolumn were eluted into the nebulizer of FAAS in 10 s with ethanol acidified with 1％ HNO_3(3.0 mL/min). A good precision(1.6％ for 100μg/L Co(Ⅱ), n=10), a high enrichment factor 17.2, with detection limit (3σ) 3.2μg/L, and sample throughput (90 h~(-1)) were obtained. The method was applied to the certified reference materials(CRMs), NBS-362 and NBS-364, for the determination of cobalt and the results were in good agreement with the certified values.     

Studies on the Electrochemical Behavior of Bleomycin at a Co/GC Ion Implantation Modified Electrode and Its Application

In a 0. 10 mol/L HAc-NaAc buffer solution (pH = 4. 59), a sensitive reduction peak of bleomycin was observed by linear sweep voltammetry at a Co/GC ion implantation modified electrode. The peak potential was-0. 73 V(iw. SCE). The peak current was proportional to the concentration of bleomycin over the range of 5.0 × 10-8-1.0× 10-6 and 1.0× 10-6-1. 0 × 10-5 mol/L with a detection limit of 2.0 × 10-8 mol/L. The electrochemical behavior of the reduction peak of bleomycin at the Co/GC modified electrode was studied by linear sweep and cyclic voltammetry and applied to the determination of bleomycin in urine. This method is simple, rapid and reliable. The reduction process is quasi-reversible. The experiments of AES and XPS showed that Co was surely implanted into the surface of GCE and the depth distribution of Co was in good agreement with Gooses normal distribution; the implanted Co at GCE improved the electrocatalytic activity.     

Time-resolved ESI-MS Investigation on Reduction and Alkylation in Unfolding Process of Lysozyme

The kinetic procedure of the unfolding of lysozyme induced by the reduction of disulfide was monitored by the time-resolved ESI-MS with a sheath liquid assistant electrospray interface. It was found that the reduction process for the eight disulfides had a less difference in the reaction time after denatured treatment. In addition, the alkylation of the reduced free thiols was much slower than the reduction procedure. An artifact peak produced by the CID fragmentation in the mass spectra was identified and the possible mechanism of the Hofmann elimination reaction was proposed.     

New Soluble Fluorinated Polyimides

Aromatic polyimides have been widely used in aerospace, electrical and electronic applications due to their outstanding thermal stability, mechanical strength at elevated temperature and electrical properties1-3. However, polyimide materials are usually difficulty to fabricate owing to their insolubility in most organic solvents and infusibility. Besides solubility, low moisture uptake of polyimide is also a major concern for microelectronics and optical applications. The present article descr…     

铜基催化剂催化合成气一步合成甲醇和甲酸甲酯IV.空速、反应时间、杂质和Cu-Cr摩尔比的影响(英文)

在低温低压和浆态反应条件下,考察了空速、反应时间、杂质及Ｃｕ－Ｃｒ摩尔比对铜基催化剂催化合成气一步合成甲醇和甲酸甲酯反应的影响。实验结果表明,空速对催化剂活性有较显著的影响;ＣＯ转化率与反应时间无关,但Ｈ２的转化率与反应时间有关。在１５小时之内Ｈ２的转化率随反应时间增加而缓慢增加,此后与反应时间无关。此外,高浓度的杂质使催化剂的活性和寿命下降,而且Ｃｕ／Ｃｒ摩尔比和热处理气氛对催化剂的物相和活性也有显著的影响。     

Crystal and Molecular Structure of 1-Phenoxy(α-methyl)acetyl-2-diethylamino-3-phenyl-1,3,2-diazaphospholidin-4-one-2-sulfide

1　INTRODUCTIONAsherbicides,thearyloxycarboxylicacidssuchas2,4-D(2,4-Dichlorophenoxyaceticacid)etc.havenotbeenusedwidelysince1970sbecauseoftheircausingenvi-ronmentalpollutionandinjuriestothecrops.Studiesonthenewtypeofherbicideshavebeendevelopinginrecentyears.Itwasreportedrecentlythatthederivativesofdiazaphospholidinoneorthecorrespondingthionespossessinterestingherbicidalactiv-ity[1～3].Itwasalsoknownthat1,4,2-diazaphospholidine-5-thione-2-oxideshasgoodselectiveherbicidalactivity[4,5],but…     

K3C60单晶膜的同步辐射光电子谱研究

在C₆₀单晶(111)解理面上制备出厚度约30 nm的K₃C₆₀单晶膜.利用同步辐射光源,在低温下(约150K)测量了样品法向发射的角分辨光电子谱.观察到K₃C₆₀导带和价带明显的色散.导带的光电子谱峰可清晰分辨出4个子峰,这些子峰的最大色散超过0.5eV,并且色散曲线与K₃C₆₀的一维无序晶体结构模型下的能带理论基本吻合,只是子带间隔差异较大.     

洁净和氧吸附的Cu(100)表面重构的理论研究

The interaction of atomic oxygen with the clean Cu(100) surface has been studied by means of cluster and periodic slab models density functional theory in the present paper. The Cu(4,9,4) cluster and a three-layer slab with c(2×2) structure are used to model the perfect Cu(100) surface. Three possible adsorption sites,top, bridge and hollow site, were considered in the calculations. The predicted results show that the hollow site is the prefer site for atomic oxygen adsorbed on Cu(100) surface energetically. This is in good agreement with the experiment. The calculated binding energies are respective 2.014, 3.154 and 3.942 eV for top, bridge and hollow sites at mPW1PW91/LanL2dz level for the cluster model. The geometry of Cu(100) surface has also been optimized theoretically with various density functional methods and the results show that the prediction from the B3PW91/LanL2dz and mPW1PW91/LanL2dz reproduce the experimental observation.The frontier molecular orbitals and partial density of states analysis show that the electron transfer from the d orbital of substrate to the p orbital of the surface oxygen atom.     

Determination and Temperature Dependence of Plateau Modulus for Polymerization of Propylene to Isotactic Polypropylene with Ultra-high Molecular Weight under Catalysis of Ziegler-Natta Catalyst

The viscoelastic behavior of isotactic polypropylene with ultra-high molecular weight (UHPPH) and broad molecular weight distribution(MWD), produced in the presence of Ziegler-Natta catalyst, was investigated by means of oscillatory rheometry at 180 and 200 ℃, whose loss modulus(G") plots at 180 and 200 ℃versus the natural logarithm of angular frequency(ω) present a pronounced maximum at 34.35 and 69.21 rad/s, respectively, and do not show a maximum peak at 0. 01-100 rad/s for Ziegler-Natta catalyzing ethylenepropylene random copolymerization (PPR) with a conventional molecular weight and broad MWD. The fact indicates that the high molecular weight is responsible for a maximum peak of G"(ω) vs. lnω curves for UHPPH. This makes it possible to determine the plateau modulus (G0N) of UHPPH from a certain experimental temperature G"(ω) curve directly. For UHPPH, the G0N determined to be 4. 28×105 and 3. 62×105 Pa at 180and 200 ℃, respectively, decreases with the increase of temperature and is independent of the molecular weight, which directly confirms reputation theoretical prediction that the G0N has no relation to the molecular weight.     

Crystal Structure of Ethyl 4-benzoyl-1a,2,3,4-tetrahydro-3-methyl-1a-(4-methylphenyl)-1H-azirino〔1,2-a〕〔1,5〕 benzodiazepine-1-carboxylate(C_(28)H_(28)N_2O_3)

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