马来酸酐溶液法接枝无规聚丙烯的研究

采用溶液法选用极性单体马来酸酐,在非隔氧条件下,对无规聚丙烯进行接枝改性。考察了不同温度、引发剂浓度、反应时间等因素对产物接枝率的影响,并用正交法指出影响因素的显著性,确定了控制ＭＡＰＰ接枝率的主要参数,找出了合成马来酸酐接枝无规聚丙烯（ＭＡＰＰ）的方法、体系与条件。采用红外及化学滴定等方法对聚合物的接枝率和结构进行了表征,证实了实验结果及相关理论的解释。     

Study of solid-state catalytic isotope exchange of hydrogen inl-hydroxyproline under the action of spillover tritium

Reaction of high-temperature solid-state catalytic isotope exchange (HSCIE) of hydrogen in L-hydroxyproline was studied byab initio quantum-chemical calculations. A one-center synchronous mechanism of isotope exchange between the amino acid and the H₃O⁺ model acidic center was considered. The structures of transition states of the reaction and the activation energies were determined. Relative reactivity of the C−H bonds in the hydroxyproline molecule under conditions of HSCIE was studied. The results obtained are in agreement with experimental data on the stereoselectivity and regioselectivity of the HSCIE reaction,viz., the lower the calculated activation energy of isotope exchange, the larger the portion of hydrogen substituted by tritium in a given position of the amino acid molecule. The enhancement of the reactivity under conditions of solid-state isotope exchange can be associated with additional interaction between the exchanging H atoms and the electron-donor O and N atoms of the amino acid molecule in transition state. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1056–1060, June, 1999.     

Kinetic Study of the Isotope Exchange Reactions of Malonic Acid and Malonate Ion Using 1H NMR Spectroscopy. Inhibition of Acid and Base

The isotope exchange reactions of malonic acid and a malonate ion were investigated in acidic and basic D₂O solutions, respectively, using ¹H NMR spectroscopy. The isotope exchange reaction of malonic acid is inhibited by the presence of DNO₃ (0–3 M) and DSO₄^? ion (0–0.1 M), whereas it is catalyzed by the presence of DSO₄^? ion (> 0.2 M), D₃PO₄, D₂PO₄^? ion or DPO₄^2– ion. The order of relative reactivity for catalyzing the isotope reaction of malonic acid in D₂O is DPO₄^2– > D₂PO₄^? > D₃PO₄ > DSO₄^? > DNO₃. The rate of the isotope exchange reaction of malonate ion in D₂O decreases to a minimum and then increases with increased [NaOD]₀. The mechanism of the isotope exchange reaction of malonic acid in acidic D₂O is different from the general acid-catalyzed mechanism generally observed for organic acids like acetic and dichloroacetic acids. The bimalonate ion plays an important role in the isotope exchange reactions of this system.     

Stable Marriage and Genetic Algorithms: A Fertile Union

We describe a pair of genetic algorithms for solving two stable matching problems. Both stable matching problems we will consider involve a set of applicants for positions and a set of employers. Each applicant and each employer prepares a rank order list of a subset of the actors in the other set. The goal is to find an assignment of applicants to employers in which if applicant a is not assigned to employer b then either a prefers his assignment to b or b prefers its assignment toa . In other words, no applicant/employer pair can both improve their situations by dropping their current assignments in favor of each other. Our goal will be to enumerate the stable matchings. One of the problems we will consider is the well-known stable marriage problem, in which neither applicant nor employer preference lists are linked. In the other problem, we will allow pairs of applicants who form a couple to submit joint rank order lists of ordered pairs of employers.     

Facility for preparation of gas mixture in muon catalyzed fusion experiments

A facility is described that allows safe handling of high tritium gas activity as dozens kilocuries in a regular laboratory environment. It is used to make and deliver into the target a mixture of specific isotopic composition with the contamination requirement of 10^-7 v.f. for Z>1 elements, and recover it upon completion of operation. With this facility, efforts have been accomplished to investigate into the muon catalyzed fusion on two targets – liquid tritium and high-pressure tritium types. Also, the operation range was 0.1–120 MPa for pressure and 20–800 K for temperature and the amount of tritium used was about 100 kCi. The facility showed reliability in operation without indications of radiation beyond the safety level. This revised version was published online in August 2006 with corrections to the Cover Date.     

A labeling scheme for young tableaux spanning representations of permutation group S(N)

A structure‐dependent labeling scheme for the Standard Young Tableaux spanning the representations of the permutation group is outlined in the present work. This scheme is used to generate the representations of a select class of permutations such as dense cycles and general transpositions of the group using minimal storage requirements. Two distinct approaches are outlined for generating the tableaux in the present labeling scheme. Detailed application has been made to two‐column Young diagram representations that are extremely useful in electron correlation studies in molecules. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 185–190, 2000     

660 MW超临界W火焰锅炉低负荷稳燃特性研究

"碳中和"、"碳达峰"的提出预示着未来煤电机组将在更低的负荷运行,用于燃烧无烟煤、贫煤等低挥发份煤种的W火焰锅炉低负荷运行时会出现燃烧稳定性问题.以某660MW超临界W型火焰锅炉为对象开展了针对低负荷稳燃特性的研究,进行了100％、60％、55％、45％ THA工况的试验研究与数值模拟解析,35％ THA工况理论预报....     

Surface‐active metal‐coordinated oligoperoxidic radical initiators. I. The interrelation between the microstructure of ditertiary oligoperoxides and their ability to form stable metal complexes

Carbon‐chain heterofunctional oligoperoxides (HFOs) with ditertiary peroxidic, carboxy, or hydroxy groups formed stable coordinated complexes through their interaction with transition‐metal salts in organic solutions. The oligomeric metal complexes (OMCs) were separated from the reaction mixture and investigated through elemental analysis, voltammetry, and atom‐adsorption, IR, and UV spectroscopy. From these investigations and the calculated values of the mole fraction and formation constants of the stable complexes of the copper cations and HFOs, the probable cooperative mechanism of the complex formation by such oligomers was suggested. The existence of two levels of HFO molecule ordering, namely HFO microstructure and the structure of the hydrogen‐bonded complexes formed by HFOs, explained the cooperative mechanism and some characteristics of the OMC formation. The mole fraction and formation constants of the OMCs were interrelated with the disposition of the complex‐forming groups in the chain of HFOs. From the experimental data, it can be concluded that the complex‐forming groups of the HFOs possessed different reactivities both in the complex formation with metal cations and in the reactions involving the resulting OMCs. The shift in the half‐wave potential of the  O:O bond reduction during the transition from the HFO to a mixture of HFO and Cu²⁺ and to OMC indicated an increase in its reactivity. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 516–527, 2000     

Melt modification of poly(styrene‐co‐maleic anhydride) with alcohols in the presence of 1,3‐oxazolines

Various copolyesteramides were prepared by melt compounding at 220 °C involving reaction of poly(styrene‐co‐maleic anhydride), SMA, with 6, 17, and 28 wt % maleic anhydride content, and 1‐dodecanol, C12OH, in the presence of 2‐undecyl‐1,3‐oxazoline, C11OXA. Copolymer architectures were examined by means of ¹H NMR, FTIR, DSC, and TGA using model compounds prepared via solution reactions. While conversion of anhydride with alcohol was poor due to the thermodynamically favored anhydride ring formation, very high conversions were achieved when stoichiometric amounts of C11OXA were added. According to spectroscopic studies esteramide groups resulted from reaction of oxazoline with carboxylic acid intermediate. In the absence of alcohol, C11OXA reacted with anhydride to produce esterimides. Effective attachment of flexible n‐alkyl side chains via simultaneous reaction of C12OH and C11OXA resulted in lower glass‐transition temperatures of copolyesteramides. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1222–1231, 2000     

Proximity‐preserving labeling schemes

This article considers informative labeling schemes for graphs. Specifically, the question introduced is whether it is possible to label the vertices of a graph with short labels in such a way that the distance between any two vertices can be inferred from inspecting their labels. A labeling scheme enjoying this property is termed a proximity‐preserving labeling scheme. It is shown that, for the class of n‐vertex weighted trees with M‐bit edge weights, there exists such a proximity‐preserving labeling scheme using O(M log n + log²n) bit labels. For the family of all n‐vertex unweighted graphs, a labeling scheme is proposed that using O(log² n · κ · n^1/κ) bit labels can provide approximate estimates to the distance, which are accurate up to a factor of In particular, using O(log³n) bit labels, the scheme can provide estimates accurate up to a factor of $\sqrt{2 \log n}$. (For weighted graphs, one of the log n factors in the label size is replaced by a factor logarithmic in the network's diameter.) © 2000 John Wiley & Sons, Inc. J Graph Theory 33: 167–176, 2000