Accurate measurement of magnesium content in alphaolefins by laser induced breakdown spectroscopy （LIBS） technique

In this paper,results are presented on first application of laser-induced breakdown spectroscopy(LIBS) technique for quantitative determination of Mg concentration in alpha-olefins. It is demonstrated that this technique gives accuracies in Mg concentrations which are comparable with those of traditional methods,as ICP-OES,in short times and without need for sample preparation. Limits of detection for Mg of the order of 500 ppb are demonstrated. Moreover,a brief discussion about the realization of proper calibration curves and the definition of the limit of detection(LOD) is reported.     

Protonierung und Solvatation schwacher organischer Basen. I. Zur Basizität von ω-Chloracetophenonen

Protonation and Solvation of Weak Organic Bases. I. Basicity of ω-Chloroacetophenones The protonation equilibria of ω-chloroacetophenone and some p-substituted derivates have been studied in the acid system H₂O/H²SO⁴/SO₃ by u.v. and ¹H-n.m.r. spectroscopy. From the determined H₀ values for half-protonation _pK_BH+ values were calculated by means of the solvation parameters m of YATES and McCLELLAND . The (H₀)_1/2 and the _pK_BH+ values were successfully correlated with σ_p and σ_p⁺ substituent constants.     

Lichtinitiierte Polymer- und Polymerisationsreaktionen. 14. Radikalische Photopolymerisation mit Kaliumtrisoxalatocobaltat-Aryloniumsalz-Systemen

Light Induced Polymer and Polymerization Reactions. 14. Radical Photopolymerization by Potassium Trisoxalato Cobaltate Arylonium Salts Systems. The photopolymerization of acrylamide (AA) by trisoxalato cobaltate ([Co(ox)₃]³⊖) is inefficient because the produced nucleophilic ·CO₂⊖-radicals are oxidized or they terminate with polymer radicals. If onium compounds are added to this system the initiation efficiency is increased as follows : p-CH₃OC₆H₄N₂⊕>Ph₂I⊕>PhCOCH₂S(CH₃)₂⊕>Ph₃S⊕. By means of quantum yield measurements a mechanism was proposed including the electron transfer from ·CO₂⊖ to onium compounds. The produced radicals also initiate the polymerization of AA. The exponent m of the polymerization rate (v_p ≈︁ [AA]^m) is decreased from 1.4 to 1.1 in the presence of Ph₂I⊕, deciding the decrease of termination reaction between ·CO₂⊖ and polymer radicals. In comparison with K₃[Fx(ox)₃] the corresponding cobalt complex possesses higher polymerization quantum yields for AA.     

某厂600MW锅炉末级过热器异种钢焊口泄露原因分析及其改造

针对某厂600MW锅炉末级过热器异种钢处发生爆管事故,通过宏观检查、力学检测、管道尺寸检测、金相分析等方法,分析了末级过热器异种钢焊口出现爆管的原因.为解决末级过热器异种钢焊口泄露问题,对末级过热器异种钢焊口位置进行改造,改造后末级过热器异种钢焊口处未发生爆管现象,增强锅炉安全可靠运行.     

Komplexchemisches Verhalten von N-substituierten 2-(o?Hydroxyphenyl)-Δ2-imidazolinen als Metallextraktionsmittel

The Coordinative Behaviour of N-Substituted 2-(Δ²-Imidazolin-2-yl)-phenols as Metal Extractants N-Substituted 2-(Δ²-imidazolin-2-yl)-phenols (R⁴NNOH) are obtained by the reaction of N-alkyl diaminoethane-1, 2 and 2-hydroxybenzoic acid esters. In contrast to many other copper(II) complexes with the donor set N₂O₂²⁻( A ), the species Cu(R⁴NNO)₂( B ) are easily soluble in nonpolar solvents. The reason is the monomeric square-planar structure of B , which differs from the polymeric distorted octahedral structure of A . The two maxima in the vis-spectra of Cu(R⁴NNO)₂ and Ni(R⁴NNO)₂ are assigned to the 3 dxy → 3 dx²-y² and the 3 dxz, 3 dyz → 3 dx²-y² electron transitions. The shift of these maxima, which is connected with the dissolution in chloroform, is explained by the formation of hydrogen bonds between the solvent and the N-alkylated nitrogen atoms of the ligands. ¹H-n. m. r.-spectra and solubility of the ligands and the crystal structure of Cu[(C₄H₉)NNO]₂ are described.     

Physico-chemical Properties of Black Pepper Starch

Unusually small-sized (2 - 2.5 μ) starch granules were isolated from black pepper (Piper nigrum) in 25 – 38% yield. The granules having an amylose content of 18% were non-ionic in nature and exhibited low solubility and low swelling power in water, but high solubility in DMSO. The amylogram peak viscosity of the starch was about 530 B. U. with a very little set back (∼ 550 B. U.) on cooling, indicating a stable linear molecule very strongly associated with amylopectin. X-ray power pattern revealed the starch granules to be of A-type.     

Scanning Electron Microscopy of Enzyme-digested Starch Granules

The study deals with comparison of the susceptibility to fungal glucoamylase and salivary α-amylase of starch granules from navane, panivaragu, black pepper and black gram. The crude glucoamylase was purified by fractionation and column chromatography to give two pure fractions of which one was used. The rate of amylolysis was followed by estimating the amount of glucose and maltose released. The type and extent of damage of the starch granules were observed by scanning electron microscopy which revealed characteristic degradation patterns in navane and panivaragu, whereas black gram granules were resistant to the attack. Very small-sized black pepper starch granules did not exhibit any obvious signs of amylolytic attack.     

Herstellung von Phenolharzen unter Verwendung von Stärkeprodukten

Usage of Starchy Products for Preparation of Phenolic Resins. Incorporation of starches and starch hydrolysates in phenolic resins of novolak and resol type has been investigated via acid catalyzed dehydration to 5-hydroxymethylfurfural (HMF) in the presence of phenol and formaldehyde. Due to formation of HMF/phenol-condensates savings up to 40% phenol and 65% formaldehyde are possible in comparison to commercial resins. Besides very low amounts of residual monomers, curing is accelerated with increased carbohydrate incorporation, which can be used to reduce time consuming manufacturing processes. Especially starch hydrolysates with different average molecular weights can be used in a very flexible way to achieve special requirements like softening points, mol weight distributions, viscosities and curing behaviour.