Dilepton production from ρ-mesons in a quark-gluon plasma

Assuming that ρ-mesons exist in a quark-gluon plasma at temperatures close to the QCD phase transition, we calculate the dilepton production rate from q-ˉq annihilation via a ρ-meson state using Vector Meson Dominance. The result is compared to the rates from direct q-ˉq annihilation and from π⁺-π⁻ annihilation. Furthermore we discuss the suppression of low mass dileptons if the quarks assume an effective mass in the quark-gluon plasma. Received: 8 September 1999 / Revised version: 22 October 1999     

茜素红S螯合树脂分离富集测定地质样品中的痕量金、铂和钯

用螯合树脂对金属进行分离富集及测定,前人已做了许多有意义的研究^[1～4].曾用含键合S双硫腙(P-D)和脱氢双硫腙(P-DT)功能团的离子交换树脂和螯合树脂分离金和铂族金属^[5],用双硫腙负载树脂分离富集Cu(Ⅱ)^[6]。     

Awn Stem-Derived High-Activity Free-Metal Porous Carbon for Oxidation Reduction

Designing oxygen reduction reaction (ORR) catalysts with excellent performance has far-reaching significance. In this work, a high-activity biomass free-metal carbon catalyst with N and S co-doped was successfully prepared by using the KOH activated awn stem powder as the precursor with organic matter pore-forming doping technology, which is named TAAS. The content of pyridine nitrogen groups accounts for up to 36% of the total nitrogen content, and a rich pore structure is formed on the surface and inside, which are considered as the potential active centers of ORR. The results show that the specific surface area of TAAS reaches 191.04 m²/g, which effectively increases the active sites of the catalyst, and the initial potential and half slope potential are as high as 0.90 and 0.76 V vs. RHE, respectively. This study provides a low-cost, environmentally friendly and feasible strategy for the conversion of low-value agricultural and forestry wastes into high value-added products to promote sustainable development of energy and the environment.     

Synthesis of α-Oxoketene CyclicO,S and S,S Acetals

Ｓｙｎｔｈｅｓｉｓｏｆα－ＯｘｏｋｅｔｅｎｅＣｙｃｌｉｃＯ,ＳａｎｄＳ,ＳＡｃｅｔａｌｓＬＩＵＱｕｎ,ＸＵＢａｉ－ｌｉｎｇａｎｄＺＨＡＯＨｏｎｇ－ｗｕ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ,ＮｏｒｔｈｅａｓｔＮｏｒｍａｌＵｎｉｖｅｒｓｉｔｙ,Ｃ...     

钠硫电池电极结构改进与电池性能研究

研究了新型的钠硫电池钠极钠芯结构和硫极预制结构对电池性能影响．实验表明,钠极的钠芯结构不仅能改善电池放电性能,而且有利提高电池的比能量和安全性;内衬氧化铝纤维的硫极预制结构能缓和界面极化,改善电池充电性能．改进电极结构后的钠硫电池也有利于电池向商品化,实用性发展     

S~2O~8^2^-处理的ZrO~2固体超强酸上的正丁烷异构化反应

首次报道了由浸渍过硫酸根的方式制备固体超强酸。讨论了焙烧温度、浸渍浓度以及ZrO~2前驱体沉淀条件对样品性质的影响,并研究了它们对正丁烷异构化反应性能。实验结果表明,600-650℃焙烧、0.25-0.50mol/LS~2O~8^2^-浸渍反加沉淀的ZrO~2具有最高超强酸性。与相同条件下制备的SO~4^2^-/ZrO~2相比,S~2O~8^2^-/ZrO~2上正丁烷250℃异构化活性是SO~4^2^-/ZrO~2的2倍,可能是由于它具有较多的中强酸位并具有与SO~4^2^-/ZrO~2不同的活性位结构。     

S，S-螯合配位的Pd(Ⅱ)配合物的合成及其对二肽水解促进作用的研究

本文报道合成了一系列S,S-型螯合配体—1,2-二苯硫基乙烷及其衍生物。制备了它们与Pd(Ⅱ)形成的配合物,并研究了这些配合物促进下的二肽水解反应动力学。结果发现这些配合物对二肽的水解反应有促进作用,该水解反应是通过配位水的进攻机理进行的,水解速率随着与Pd(Ⅱ)配位的配位水的个数的增加而加快。     

Mellin and Green symbols for boundary value problems on manifolds with edges

We introduce the algebra of smoothing Mellin and Green symbols in a pseudodifferential calculus for manifolds with edges. In addition, we define scales of weighted Sobolev spaces with asymptotics based on the Mellin transform and analyze the mapping properties of the operators on these spaces. This will allow us to obtain complete information on the regularity and asymptotics of solutions to elliptic equations on these spaces.     

Germes de d\'etermination infinie dans des classes lisses

We give sufficient conditions of infinite determinacy (in the sense of Mather) with respect to right equivalence, in subrings of C ^∞ (ℝ ⁿ ,0) defined by estimates on successive derivatives, such as rings of Gevrey germs. In this quantitative setting, a defect (hidden in the classical C ^∞ case) appears between the regularity of equivalent germs and the regularity of local diffeomorphisms of (ℝⁿ,0) giving the equivalence. Our conditions yield precise estimates of this defect, related to some suitable Łojasiewicz exponents of critical loci. We also show that the result is sharp in general. Received: Received: 27 May 1998     

丙炔醇聚合股对铁在酸性溶液中的缓蚀作用

应用电化学交流阻抗谱技术研究了Ｆｅ／Ｈ_２ＳＯ_４与Ｆｅ／Ｈ_２ＳＯ_４＋Ｈ_２Ｓ体系中丙炔醇（ＰＡ）聚合膜的形成及其缓蚀作用,同时利用ＳＥＭ、ＡＦＭ及ＥＤＸ对ＰＡ聚合不同时期铁表面腐蚀形貌进行观测与成分分析．结果表明,Ｆｅ／Ｈ_２ＳＯ_４与 Ｆｅ／Ｈ_２ＳＯ_４＋ Ｈ_２Ｓ体系中 ＰＡ可逐渐聚合成膜,从而有效抑制基体的腐蚀,使电极表面较为平整,微米尺度下呈现规则的块状结构;但Ｆｅ／Ｈ_２ＳＯ_４体系中宏观上ＰＡ并未形成连续的保护膜,导致电极表面局部发生腐蚀;而Ｆｅ／Ｈ_２ＳＯ_４＋Ｈ_２Ｓ体系中,Ｈ_２Ｓ、ＨＳ－在电极表面的吸附减缓了ＰＡ聚合成膜,但长时间腐蚀后,由于硫化物的生成覆盖在ＰＡ聚合膜上,使其具有长期缓蚀效能．