由4-羟基苯甲醛合成香兰素的CNDO/2研究

用CNDO/2法研究了从4-羟基苯甲醛合成香兰素的化学反应，并作了理论解析。结果表明，合成路线是可行的，总收率为85％。     

模拟污水中氮、磷对水稻幼苗过氧化氢酶和乙醇酸氧化酶的影响

以水稻为材料，研究了不同浓度的模拟污水中Ｎ、Ｐ对幼苗过氧化氢酶（Ｃａｔａｌａｓｅ，ＣＡＴ，ＥＣ１．１１．１．６）、乙醇酸氧化酶（Ｇｌｅｃｏｌａｔｅｏｘｉｄａｓｅ，ＧＯ，ＥＣ１．３．３．１）、过氧化物酶（Ｐｅｒｏｘｉｄａｓｅ，ＰＯＤ，ＥＣ１．１１．１．７）和叶绿素含量的影响．结果表明：低浓度Ｎ、Ｐ（分别；在０～４．２８ｍｍｏｌ·Ｌ－１、０～０．２ｍｍｏｌ·Ｌ－１范围）可诱导ＣＡＴ活性增大，而后下降，Ｎ、Ｐ浓度分别超过８．５６ｍｍｏｌ·Ｌ－１和０．４ｍｍｏｌ·Ｌ－１后，活性又升高；ＰＯＤ的活性变化与ＣＡＴ变化很相似．Ｎ、Ｐ浓度分别在０～６．４２ｍｍｏｌ·Ｌ－１、０～０．３ｍｍｏｌ·Ｌ－１范围，ＧＯ活性随Ｎ、Ｐ浓度增高而活性下降，超过６．４２ｍｍｏｌ·Ｌ－１、０．３ｍｍｏｌ·Ｌ－１后，则随Ｎ、Ｐ浓度增大而增大．这可能是高浓度Ｎ、Ｐ可提高水稻的光呼吸的结果．另外，污水中Ｎ、Ｐ抑制叶绿素的合成，使叶绿素的含量降低；低浓度污水Ｎ、Ｐ促进根生长，高浓度Ｎ、Ｐ抑制根生长     

Selective and rapid ion-chromatographic determinations of alkaline earth metals and applications to the analysis of baryte

Summary An ion-chromatographic procedure is described for the determination of Mg, Ca and Sr in the presence of an excess of Ba in baryte samples after a soda-potash digestion. The procedure is performed by coupling a strong acid exchanger (based on silica gel) and a post-column derivatisation using PAR-Zn-EDTA reagent and photometric detection at 495 nm. Further optimizations resulted in a mobile phase consisting of a citrate-oxalate-ethylendiamine solution. Details of the optimization procedures and the results of some baryte analyses are presented. The concentrations of Mg, Ca and Sr ranged between 0.01 and 2%. These results were verified using two reference methods (AAS and complexometric titration).

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Selektive und schnelle ionen-chromatographische Bestimmungen von Erdalkalimetallen mit Anwendungen in der Barytanalyse

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Dedicated to Prof. Dr. G. Tölg on the occasion of his 60th birthday     

Mechanism and Dynamics of the Addition of Lithium Hydride to Acetylene

Reaction ergodography for the addition of lithium hydride to acetylene indicates that the lithium hydride, in both monomeric and dimeric forms, reacts with the acetylene via two similar and competitive pathways. Hence, we have obtained the pseudo-first-order rate constant of this reaction.     

微生物食物链培养系统的极限性态

本文考虑多种微生扬在一个培养室中混合培养,这些微生物之间是作为食物链而相依相存的,本文假定营养液的浓度及微生物对资源的消耗率等因素都是时间的有界函数,得到了微生物种群生存和绝灭的条件。     

Ionen-Chromatographie yon Gallium, Indium und Thallium mit Anwendungen in der Erzanalyse

Summary An optimal separation system is presented for the rarer elements Ga(III), In(III), Tl(III) and the main intergrowth elements such as Fe(III), Cu(II), Pb(II), Zn(II) etc., using the cation-exchange column Nucleosil SA and 0.1 mol/l tartrate –0.12% NaCl, pH 2.25, as mobile phase, by means of which complete separations of these metal ions can be obtained within 15 min. Under these chromatographic conditions, the detection sensitivities of these metal ions were compared by post column derivatisation using the reagents PAR, PAR-Zn-EDTA and 5-Br-PADAP [2(5-Bromo-pyridylazo)-5-diethylaminophenol]. The optimum detection system was 1 mmol/l PAR-0.5 mmol/l Zn-EDTA – 2 mol/l NH₃, pH 11, with a 6 m reaction coil heated to 60°C and measured at 495 nm.In addition, a technique of pre-column washing was also developed to eliminate matrix effects of sample solutions, and, if necessary, to concentrate ultra trace amounts of metal ions. A procedure is presented for the simultaneous determination of the rarer elements Ga(III) and In(III) in complex ores. Tested by analyses of synthetic and natural samples with contents of 0.004% to 0.1%, this new method shows high selectivity, good precision, simplicity and practicability.     

Evaluation of N‐hydroxymethylphthalimide in alkaline medium: Novel entry to the tricyclic [1,3]oxazepine core via an intramolecular π and O‐cationic cyclization

Fused isoindolo[1,3]benzo(or thieno)oxazepines 8a,b and one of their positional isomers aromatic tricyclic N,O‐acetals 13b are reported to occur efficiently in a three‐step sequence from N‐hydroxy‐methylphthalimide (6) . The key step of this methodology is the intramolecular arylation of an endocyclic and/or exocyclic N‐acyliminium cation. The mechanism leading to these species, in particular to a tricyclic lactam 13b , is discussed.     

The Impact of Media on the Control of Infectious Diseases

We develop a three dimensional compartmental model to investigate the impact of media coverage to the spread and control of infectious diseases (such as SARS) in a given region/area. Stability analysis of the model shows that the disease-free equilibrium is globally-asymptotically stable if a certain threshold quantity, the basic reproduction number (), is less than unity. On the other hand, if , it is shown that a unique endemic equilibrium appears and a Hopf bifurcation can occur which causes oscillatory phenomena. The model may have up to three positive equilibria. Numerical simulations suggest that when and the media impact is stronger enough, the model exhibits multiple positive equilibria which poses challenge to the prediction and control of the outbreaks of infectious diseases. Research supported by the NNSF of China (10471066). Research supported by NSERC, MITACS and CFI/OIT of Canada.     

Absorption Spectrum from Europium Ions in Europium Oxychloride,EuOCl

We have recorded part of the UV-visible region of the electronic spectrum of EuOCl at both 292 and 77 K by diffuse reflectance spectroscopy. Illumination of the sample and collection of the reflected light was accomplished through the use of an all-quartz fiberoptic probe. Several absorption maxima were observed which result from transitions from the ⁷F₀ ground state and ⁷F₁ excited state to the ⁵D₄ ⁵G_2,4,6 ⁵L₆, and ⁵D₃ excited states of the Eu³⁺ ion.     

Modification of Cary 14H Spectrophotometer into a Fiberoptic Absorption Spectrophotometer

An efficient fiberoptic interface system was developed to convert a Gary 14 H spectrophotometer into a fiberoptic instrument. This new spectrophotometer can be used to study the UV-visible and near-IR absorption spectroscopy of radioactive samples and wastes in a confined environment.