Forward-backward multiplicity correlations in σ+ p,K + p andpp collisions at 250 GeV/c

Forward-backward multiplicity correlations in σ⁺,K ⁺ p andpp collisions at 250 GeV/c ( \(\sqrt s \) =22 GeV) are given for all charges and for the different charge combinations. The correlations are found to be caused predominantly by centrally produced particles. It is demonstrated that this result is an agreement with observations at the ISR and the CERNp \(\bar p\) -Collider. The results are compared to expectations from LUND, DPM and FRITIOF Monte Carlo models and a geometrical picture relating correlations in hadron-hadron collisions toe ⁺ e ^? data in terms of impact parameters is tested.     

聚醚醚酮酮和含联苯聚醚醚酮酮共聚物的熔融热

根据Ｆｌｏｒｙ热力学统计理论和比容－熔融热作国法，由ＤＳＣ结果得到了不同联苯含量的聚醚醚酮酮－含联苯聚醚醚酮酮（ＰＥＥＫＫ－ＰＥＢＥＫＫ）共聚物的熔融热，两种方法获得的结果吻合。在此基础上给出了ＰＥＥＫＫ－ＰＥＢＥＫＫ共聚物不同联苯含量的熔点计算表达式。结果还表明，随着联苯含量ｎＢ，的变化，明显改变；当ｎＢ＝０．３５时，ＰＥＥＫＫＰＥＢＥＫＫ共聚物的值最小。     

Effect of pressure on pedal motion in stilbene molecular crystals and its dependence on the crystallographic site

We report computer simulation of a stilbene molecular crystal as a function of pressure up to 4 GPa. Molecular structure and the crystal structure of stilbene have been characterized by calculating the radial distribution function and dihedral angle distribution, features associated with pedal motion and cell parameters. Results suggest that the population of minor conformer at site 2 disappears altogether above 1.25 GPa. In contrast, the population of minor conformer at site 1 remains at around 12%. Pedal motion is not observed beyond a pressure of 0.8 and 1.4 GPa at site 1 and site 2, respectively. Specific heat and compressibility exhibit an anomaly around 1.25 GPa. The anomaly seems to be associated with the disappearance of pedal motion at site 2. Initially, increase in pressure leads to an increase in the magnitude of lattice energy, but beyond 0.5 GPa it decreases.     

Orientational melting and reorientational motion in a cubane molecular crystal: a molecular simulation study

Detailed molecular simulations are carried out to investigate the effect of temperature on orientational order in cubane molecular crystal. We report a transition from an orientationally ordered to an orientationally disordered plastic crystalline phase in the temperature range 425-450 K. This is similar to the experimentally reported transition at 395 K. The nature of this transition is first order and is associated with a 4.8% increase in unit cell volume that is comparable to the experimentally reported unit cell volume change of 5.4% (Phys. Rev. Lett. 1997, 78, 4938). An orientational order parameter, eta(T), has been defined in terms of average angle of libration of a molecular 3-fold axis and the orientational melting has been characterized by using eta(T). The orientational melting is associated with an anomaly in specific heat at constant pressure (C(P)) and compressibility (kappa). The enthalpy of transition and entropy of transition associated with this orientational melting are 20.8 J mol(-1) and 0.046 J mol(-1) K(-1), respectively. The structure of crystalline as well as plastic crystalline phases is characterized by using various radial distribution functions and orientational distribution functions. The coefficient of thermal expansion of the plastic crystalline phase is more than twice that of the crystalline phase.     

强脉冲电磁场对金属凝固组织影响的研究

提出了用强脉冲磁场和电流细化金属凝固组织的新工艺.与未经磁场或电流处理的凝固样品相比,强脉冲电磁场能够显著地改善LY12铝合金的凝固组织,使晶粒明显细化、球化;电磁场的强度愈强,这种改善效果愈明显.对该新工艺的细化机理进行了理论分析,同时,指出了实验中的新现象和新问题. 关键词：     

Magnesium oxide nanotubes: synthesis,characterization and application as efficient recyclable catalyst for pyrazolyl 1,4-dihydropyridine derivatives

Magnesium oxide nanotubes were prepared by electrospinning technique. The nanocatalysts have been characterized by various sophisticated techniques, including XRD, SEM, and TEM. The activities of these NT catalysts are promoting pyrazolyl 1,4-dihydropyridine syntheses have been extensively investigated. Various advantages associated with these protocols simple workup procedure, short reaction times, high yields and reusability of the catalyst.     

Novel Synthesis of (E)-3-Arylidene-2,3-dihydrobenzo[b][1,4]oxazepin-4(5H)-ones Using Baylis–Hillman Derivatives via Reductive Cyclization

A simple synthesis of novel (E)-3-arylidene-2,3-dihydrobenzo[b][1,4]oxazepin-4(5H)-ones from bromides of the Baylis--Hillman adducts using Fe/AcOH for the in situ reduction of nitro group, into an amino group, followed by the cyclization as a key step, has been described.     

Green synthesis of naphtho[2,3-f]quinolin-13-one and naphtho[2,3-a]acridin-1(2H)-one derivatives catalyzed by heteropoly acid supported montmorillonite K-10 clay

Herein, synthesis of a series of naphtho[2,3-f]quinolin-13-one and naphtho[2,3-a]acridin-1(2H)-one derivatives directly by one-pot multi-component reaction of 1,3-dicarbonyl compounds (1,3-indanedione/1,3-cyclohexanedione), 2-aminoantharacene/2-naphthylamine and various substituted aldehydes under solvent-free conditions using heteropoly-11-molybdo-1-vanadophosphoric acid supported on montmorillonite K-10 clay catalyst (10% PVMoK-10) is reported. The successful formation of naphtho[2,3-f]quinolin-13-one and naphtho[2,3-a]acridin-1(2H)-one derivatives was confirmed by various spectroscopic techniques. This study offers a green approach for the synthesis of novel quinolinone derivatives.     

Synthesis of N-Acyl Triazolyl-Pyrazolines via Acylation Initiated by the Hydrazone Moiety with Carboxylic Acids

An efficient synthesis of N-acyl/N-substituted acyl pyrazolines and their triazole hybrids have been accomplished via acylation of pyrazolines and pyrazoline-triazole hybrids with carboxylic acids and/or substituted carboxylic acids in the absence of activating agents/catalysts. In the present study, a mechanism envisaging the in situ generation of a new transient acylating intermediate has been proposed to explain the acylation.     

物理化学混合式教学设计与实践——以“单组分系统相变热力学”为例*

以“单组分系统相变热力学”为例介绍了物理化学混合式教学设计与教学实践。围绕课程教学目标,在课前、课中、课后的每一个教学环节中践行课程教学理念,通过“问题+案例”方式突出物理化学基本方法的应用性、普适性与前沿性,让学生在教学过程中获取原理、体验探究、发展思维、生成智慧。教学评价结果显示,绝大部分学生对混合式教学模式给予了积极的评价。