Thermodynamics of interaction between sodium bis(2‐ethylhexyl) sulfosuccinae and polymers in aqueous solutions by isothermal titration microcalorimetry

The interactions between sodium bis(2‐ethylhexyl) sulfosuccinae (AOT) and two nonionic water‐soluble polymers, including polyvinyl pyrrolidone (PVP) and polyethylene glycol (PEG) have been investigated by using isothermal titration microcalorimetry in aqueous solutions at 298.15 K. The results show that the critical aggregation concentration, which corresponding to the first turning point in the curve of experimental interaction heat versus concentration of the surfactant, is lower than the critical micellar concentration (cmc), confirming the existence of polymer‐surfactant interactions. The value of cac is not sensitive to the relative amount of polymer in low concentration range of the polymer. The mono‐layer saturated adsorption concentration, which corresponding to the second turning point, rises as the polymer concentration is increased. The interaction between PVP and AOT is stronger than that between PEG and AOT. The results also indicate that the aggregation of AOT in water and polymers solutions is entropically driven. The observed thermal effects have been interpreted in terms of the interactions of the polymer molecules with AOT monomers or the molecular clusters. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 275–283, 2006     

Laser beam alignment by fast feedback control of both linear and angular drifts

A new way to enhance the directional stability of laser beams with alternating intensity by fast feedback control of both linear and angular drifts has been proposed for alignment of laser beams at higher accuracy. Both linear and angular drifts of laser beams, processed through light intensity modulation and primary alignment using single-mode optical fiber (SMOF), are separated using light path arrangement and detected using phase-lock technique, and are controlled using fast feedback control mechanisms according to their detected magnitudes, so that both linear and angular drifts are suppressed to enhance the directional stability of the emitting laser beams. Theoretical analyses and preliminary experimental results indicate that the approach proposed can be used to achieve an alignment accuracy of more than 10⁻⁸ rad.     

KINETIC STUDY OF THE OXIDATIVE COUPLING OF METHANE OVER La_2O_3/BaSO_4 CATALYST

IntroductionOxidativccouplingofmethanc(0CM)hasbccnthcsubjcctofmuchintcrcstrcccntl}Man}'mctaloxides,alkali-mctaI-promotcdmctaloxidcs-mixcdmcta1oxidcsandchlorinc-prom0tedmCtuloxidcshavcbecnf0undtobcactivcfor0CMHot` cvcr.thcrcisatprcscntnoclearagreemcntaboutthcmcchanismofthecouplingrcaction.T\`omodclsll1.thcthdeal-rcdoxandthcLangmuir-Hinshtt-oodmcchanisms.havcbccndcvcIopcdtodcscr1bc0CMreation-thecsscntialdiffercnccbctt"ccnthctt"omodclsisthatthclattcrinvolvcsadsorbedmothancasarcactionintcrmcd…     

各种实际光束的M~2参数特性比较

首先证明基模高斯光束具有最小的Ｍ~２值，进而讨论了多模激光束、部分相干光束和波前畸变光束的Ｍ~２值的特性，以及相互之间的关系。     

用符号法分析恒频电流模控制的变换器闭环系统的稳态

将等效小参量符号分析法推广到恒频电流模控制的变换器闭环系统的稳态分析中,提出了占空比的精确确定法及简化确定法.其中,前者不需要有波形线性及小纹波假设,具有广阔的适用性.而后者对工程简化分析具有重要意义.所得结果均为符号表达式,易于理解电路的工作机理.     

数字HDTV地面广播传输方法

残留边带调制（ＶＳＢ）已用于现行电视的广播传输中。由于其在频谱利用率和传输性能方面的优越性，现在美国大联盟方案考虑把它用于高清晰度电视（ＨＤＴＶ）的地面广播。本文介绍应用在全数字ＨＤＴＶ广播传输中的ＶＳＢ原理及其抗多径干扰和ＰＡＬ信号干扰的方法。     

H.323呼叫模型的实现探讨

传统呼叫中心升级到IP网络呼叫中心，往往采用H．323协议。而采用H．323在IP网络呼叫中心实现CSTA呼叫模型有一定难度。本提出H．450和H．245两种实现方式，并对两进行分析和比较。     

激光诱导薄膜损伤的缺陷统计模型与光斑效应

讨论了脉冲激光诱导薄膜损伤的缺陷统计模型，在对该模型加些适当的限制条件后，运用它解释光斑效应，发现该理论模型与实验结果符合得很好。     

VSB解调器中的载波相位跟踪环

本文提出了一种专门用于数字ＶＳＢ解调的载波相位跟踪环，它实际上包括两个可视相互独立的子环，其一用于相位跟踪，另一用于幅度抖动补偿，在噪声和非噪声环境下，该环路均具有较好的性能，文中对此进行了理论分析和计算机仿真，结果表明，在ＨＤＴＶ地面传输系统约１５ｄｂ的信噪比门限下，该环路仍能可靠地工作。     

FIR spectroscopy of ethyl bromide and trioxane: New laser transitions and assignments

Eight new optically pumped far infrared laser transitions from ethyl bromide and 22 from trioxane are presented. For each new line we give the wavelength, the polarization relative to that of the pump laser and the absorption offset relative to the CO₂ center frequency. The assignment of the rotovibrational states for the pump and the emission transitions of ethyl bromide are calculated. We also partly assigned the rotational levels of trioxane.