Explicit and Dynamical Chiral Symmetry Breaking in an Effective Quark-Quark Interaction Model

A method for obtaining the small current quark mass effect on the dressed quark propagator from an effective quark-quark interaction model is developed. Within this approach both the explicit and dynamical chiral symmetry breakings are analysed. A comparison with the previous results is given.     

红霉素全合成取得成功

红霉素(Erythromycin I)是目前最重要的抗菌素之一。其全合成工作最近已在美国哈佛大学伍德沃德(Woodward)生前曾领导的研究组中获得成功。红霉素结构上属于大环内酯类抗菌素,在十四元内酯环上连接有两个特殊的糖分子。分子中共18个不对称碳     

Decomposition of Gauge Potential in Ginzburg-Landau Theory

Recently, Liu et al. proposed a so-called extended Anderson-Higgs mechanism by studying the （2＋1）-dimensional Ginzburg-Landau model in the pseudogap region of high-Tc superconductor （Phys. Rev. B 65 （2002） 132513）. We revisit this problem based on a general decomposition of the U（1） gauge potential. Using the bulk superconductor and superconduct ring as examples, we obtain a simpler expression for the extended Anderson-Higgs mechanism. In the former case we indicate that all the phase field can always be ＂eaten up＂ by the pure gauge term A｜｜. In the latter case, we decompose the phase field as θ（x） = θ1（x） ＋ θ2（x） and find that only the phase field θ1 connected with Anderson-Higgs mechanism can be canceled by the pure-gauge term A｜｜. On the other hand, the remaining phase field θ2 connected with A⊥ is multi-valued, which can induce new physical effects such as A-B effect and flux quantization. It is natural to conclude that there is no longitudinal phase fluctuation effect in high-temperature superconductors since longitudinal phase θ1 is connected with pure-gauge term.     

短孔道Pt/W-s-SBA-15催化剂的合成及甘油催化氢解制1,3-丙二醇性能的研究

合成了孔道平行于短轴方向的W原位掺杂的介孔SBA-15分子筛(W-s-SBA-15), 以其为载体制备了Pt/W-s-SBA-15催化剂, 考察了催化剂中Pt、W负载量变化对甘油氢解制1,3-丙二醇(1,3-PDO)性能的影响. 采用多种手段对催化剂的形貌、活性组分Pt和W的存在状态、催化剂的酸性等性质进行了系统的表征. 催化剂评价结果表明, 随着Pt、W负载量的增加, 甘油的总转化率和液相转化率(CTL)提高, 而1,3-PDO选择性呈先升高后降低的火山型变化趋势. 在Pt负载量为4.0 wt%、W/Si物质的量比为1/480的4Pt/W-s-SBA-15(1/480)催化剂上, 在433 K、H₂压力4.0 MPa、反应时间24 h的条件下, 甘油氢解制1,3-PDO的得率可达49.0%. 根据表征结果, 我们发现在Pt/W-s-SBA-15催化剂上的甘油转化率与Pt活性比表面积直接相关, 而小的Pt粒径、Pt与单分散WO₄之间密切的协同作用, 则有助于提高1,3-PDO的选择性.     

基于四氰基受体单元的高效近红外热激活延迟荧光

以二吡啶并吩嗪为受体单元,三苯胺(TPA)为给体单元,设计合成了近红外(NIR)热激活延迟荧光(TADF)材料11,12-双[4-(二苯基氨基)苯基]联吡啶[3,2-a:2’,3’-c]吩嗪-3,6,10,13-四甲腈(FCNPZ-TPA).在FCNPZ-TPA分子的受体单元上引入4个氰基增加了受体单元的吸电子能力.考虑到TPA具有优异的给电子能力,将强给体-强受体单元同时引入分子骨架中,使得FCNPZ-TPA的发射波长红移到近红外区域.另外,给体(D)和受体(A)单元之间空间位阻导致FCNPZ-TPA具有扭曲D-A分子构型,从而实现了较小的单线态-三线态能级差(ΔEST).得益于FCNPZ-TPA分子刚性骨架以及较小的ΔEST,当FCNPZ-TPA掺杂在主体4,4’-二(9-咔唑)联苯中时,该有机支光二极管器件在发射波长为742 nm处实现了8.01%的最大外量子效率(EQE).     

固相萃取-气相色谱-质谱法测定饮用水中36种农药残留量

提出了固相萃取-气相色谱-质谱联用法测定饮用水中36种农药的残留量。样品用石墨化碳/氨基复合型小柱净化和富集后,经DB-1701P弹性石英毛细管柱分离,用电子轰击离子源及选择离子监测扫描模式进行质谱测定。36种农药在一定浓度范围内呈线性关系,检出限(3S/N)在0.001 3～0.070mg.L-1之间。按方法在水样的基础上加入农药混合标准溶液做回收试验,测得回收率在90.8%～112.4%之间,测定值的相对标准偏差(n=5)在3.20%～13.2%之间。     

Effects of reagent's rotational and vibrational excitations on reaction O(3P) + H2 H2(ν = 0, 3, j = 0, 3; 5; 7; 9; 12; 15) → OH + H

To investigate the effect of reagent's rotational and vibrational excitations on the stereo-dynamics of reaction product, the title reaction is theoretically simulated using the quasi-classical trajectory (QCT) method on the ³A" and ³A′ potential energy surfaces (PESs). The reaction cross section is considered as the only scalar property in this work at four different collision energies. Furthermore the vector properties including two polarization-dependent differential cross sections (PDDCSs), the angular distributions of product' rotational momentum are discussed at one fixed collision energy. Effects of reagents' rotational excitation on the reaction do exist regularly.     

PmClAn基膜修饰电极的电化学及催化性质研究

聚苯胺作为电极修饰材料 ,已在传感器上显示出广泛的应用前景[1～ 4 ] .异丙醇 ( i- P)氧化[5,6 ] 是个较简单的反应 ,被广泛作为电催化研究的模型反应 .目前 ,i- P电化学氧化的研究集中于 Pt的多晶或单晶电极[7～ 9] ,Gonzales等 [10 ] 报道了 Pt- Sn共沉积的 PAn膜修饰电极上的异丙醇电氧化 ,但对复合材料的微观结构仍欠研究 .本文讨论 Pm Cl An基质性质对 Pt电沉积的影响 ,并探讨了 i- P在沉积 Pt微粒的 Pm Cl An功能膜电极上的氧化情况 .1　实验部分1 .1　电极的制备　聚间氯苯胺 ( Pm Cl An,本征态 ud,HCl掺杂态 d)采用乳液聚…     

Probing the QCD phase structure with higher order baryon numbersusceptibilities within the NJL model

Conserved charge fluctuations can be used to probe the phase structure of strongly interacting nuclear matter in relativistic heavy-ion collisions. To obtain the characteristic signatures of the conserved charge fluctuations for the quantum chromodynamics(QCD) phase transition, we study the susceptibilities of dense quark matter up to eighth order in detail, using an effective QCD-based model. We studied two cases, one with the QCD critical end point(CEP) and one without owing to an additional vector interaction term. The higher order susceptibilities display rich structures near the CEP and show sign changes as well as large fluctuations. These can provide us information about the presence and location of the CEP. Furthermore, we find that the case without the CEP also shows a similar sign change pattern, but with a relatively smaller magnitude compared with the case with the CEP. Finally, we conclude that higher order susceptibilities of conserved charge can be used to probe the QCD phase structures in heavyion collisions.