运用辩证法指导物理教学

在全面贯彻党的教育方针，坚持以人为本，德育为先，实施素质教育的改革进程中，作为一名物理教师如何更新教育观念，树立新的教育观，在教学实践中为学生终身学习，终身发展打下基础．围绕这一目标进行了多方面探索．物理教材中每一个概念，每一条规律都包含着辩证唯物主义的因素，在讲解物理内容时，力求用辩证的观点去分析归纳总结，     

化学势依赖于系统内的所有物质

在热力学中，关于多元系的化学势的变量集，有互不一致的两种结论.一种结论认为，某种物质的化学势，仅仅依赖于其它物质的存在，另外一种认为，不仅依赖于其它物质，也依赖于自己.本文通过详细的分析论证了，一般而言，化学势依赖于系统内的所有物质.     

有关力学谱和内耗工作的综合与回顾

本文广泛地收集了有关内耗，力学谱，超声衰减方面的专著及会议文集。反映了20世纪在此领域的英文，俄文出版的书籍。也列出了历次国际会议及前苏联，乌克兰，中国的国内会议。文中包括了点缺陷，电，声子，位错，晶界，电畴等诸方面在内的内耗与力学谱工作。     

超声射流冷却PH2自由基的激光诱导荧光谱

在４９０－５００ｎｍ波长范围内观测了超声射流冷却ＰＨ２自由基的激光诱导荧光激发谱，得到了在转动Ｋ的情况下ＰＨ２Ａ＾２Ａ１←Ｘ２Ｂ１适中（０，０，０）←（０，０，０），（０，１，０）←（０，０，０）和（０，２，０）←（０，０，０）三个振动谱带的转动分辨光谱，对这三个谱带中的约２２０条转动谱线进行了归属，其中５２条谱线是我们新标识的。从转动结构，我们获得了气相ＰＨ２自由基的全部分子常数，其中εｂｂ，ε     

学生学业成绩评价多元化的实践研究

学生的学业成绩，正常是通过平时作业、期中考斌、期末考试决定的．由于考试内容的随机性、片面性，学生发挥的偶然性，一两次的考试不能完全反映学生的智力素质、思维能力的差异，还会诱导学生过分关注那些考试内容，从而使思维僵化，知识面狭窄，大大限制了思维的发展，这些很大程度上是由评价体系造成的．因此我们应该利用评价手段，引导学生全面发展，激发学生自觉训练自己的创造思维，从而提高综合能力．     

聚心火焰在共振腔作用下引发爆轰的数值研究

 基于带化学反应的二维轴对称Euler方程，利用带有Superbee限制函数的波传播算法，对共振腔中的氢气-空气预混气的聚心燃烧进行了数值模拟，讨论了共振腔不同抛物面对起爆的影响。数值结果表明，在开始阶段，燃烧诱导的激波在轴心、火焰和固壁的反射，使火焰失稳，随后共振腔中的抛物壁面上产生一定频率和强度的反射激波，不断穿越火焰，使火焰进一步失稳，加剧了燃烧速度，最终导致爆轰的形成。同时，火焰在与激波的作用过程中，形状扭曲变形，呈封闭端小敞口端大的扁平头部蘑菇云。共振腔抛物面的不同形状引起激波聚焦位置的变化，会影响激波和火焰的相互作用，使起爆提前或推迟，甚至不起爆。     

朗道（Landau，Lev Davidovich，1908-1968）俄国物理学家（Physicist，Russia）

朗道的父亲是犹太人，石油工程师，母亲是医生。他19岁在列宁格勒大学获得博士学位。其后，他在哈尔科大大学任教授。接着，他出国研究，曾访问过玻恩，还听过海森堡聃的讲学。然后，在哥本哈根度过了若干年，随后又转到剑桥大学师从卢瑟福舭。学习。1935年，他开创了磁畴的数学研究方法，磁畴是指铁类物质中所有原子磁矩的取向都一致的微小区域。1938年，他在苏联的肃反运动中被当作德国间谍逮捕，只是因为卡皮察的亲自干预才得以释放。     

国际声化学界创办《超声声化学》杂志

自1986年4月英国皇家化学学会（RSC）举办第一届国际声地学学术会议以来，声化学的研究和应用日新月异，发表的论文数和问世的专用器材不断增长．为了促进这一新兴交叉学科的发展，及时交流声化学研究与开发信息，在颇具影响的《超声学（Ultrasonics）》杂志基础上，英国Butterwortb－Heinemann出版公司不久前宣布，另辟新刊。超声声化学（UltrasonicsSo－nochemistry）》（ISSN1350－4177），每年出版两期，世界各地发行．滚刊征稿的范围为：功率超声，空化，声致电化学，声致发光，力化学和表面之间相互作用，生物化学和生物医学，物…     

大气闪烁对自适应光学校正的影响

 激光在大气湍流中长距离近水平传输时，闪烁加强，限制了常规自适应光学的校正能力。数值研究了大气闪烁对自适应光学校正的影响，拟合得到了在Fresnel数一定时，Strehl比与Rytov方差的表达式，以及Rytov方差一定时，Strehl比与Fresnel数的表达式。结果表明，在Rytov方差较小时，纯相位校正Ｓtrehl比只与Rytov方差有关；随着Rytov方差的增加，Strehl比不仅与Rytov方差有关，还与Fresnel数有关，Fresnel数越大，校正Strehl比越大；大发射和接收孔径有利于提高校正Strehl比；在一定的Rytov方差下，Stregl比随Fresnel数增大而增加，逐步趋于饱和，达到纯相位校正的极限。     

1,1,2,2—四氯乙烷的均方根振幅,垂直振幅和离心畸变的计算

气相电子衍射和转动光谱法是测定气相分子结构的主要实验方法，而上述两种方法所获得的原子间距的定义往往是不同的，在ＧＥＤ方法中，计算分子的电子散射强度用ｒａ型原子间距，由于分析振动的影响，一般都采用热平均原子间距ｒａ，ｒａ和ｒａ之间转，可通过计算均方根振幅、垂直振幅（Ｋ）和离心畸变得到，本文以１，１，２，２－四氯乙烷为例来阐明１、Ｋ、δｒ的计算，并与文献［２］的实验结果比较，得到很好的一致。因此，本文     

A role of melanin-concentrating hormone producing neurons in the central regulation of paradoxical sleep

Background

Peptidergic neurons containing the melanin-concentrating hormone (MCH) and the hypocretins (or orexins) are intermingled in the zona incerta, perifornical nucleus and lateral hypothalamic area. Both types of neurons have been implicated in the integrated regulation of energy homeostasis and body weight. Hypocretin neurons have also been involved in sleep-wake regulation and narcolepsy. We therefore sought to determine whether hypocretin and MCH neurons express Fos in association with enhanced paradoxical sleep (PS or REM sleep) during the rebound following PS deprivation. Next, we compared the effect of MCH and NaCl intracerebroventricular (ICV) administrations on sleep stage quantities to further determine whether MCH neurons play an active role in PS regulation.

Results

Here we show that the MCH but not the hypocretin neurons are strongly active during PS, evidenced through combined hypocretin, MCH, and Fos immunostainings in three groups of rats (PS Control, PS Deprived and PS Recovery rats). Further, we show that ICV administration of MCH induces a dose-dependant increase in PS (up to 200%) and slow wave sleep (up to 70%) quantities.

Conclusion

These results indicate that MCH is a powerful hypnogenic factor. MCH neurons might play a key role in the state of PS via their widespread projections in the central nervous system.

     

Tunable mid-IR laser absorption sensor for time-resolved hydrocarbon fuel measurements

A wavelength-tunable mid-infrared (mid-IR) laser is used to make time-resolved absorption measurements of methyl-cyclohexane (MCH) and n-dodecane vapor concentration, demonstrating the use of this novel laser source for sensing hydrocarbon fuels. Two sensitive and species-specific diagnostic strategies are investigated: (1) direct absorption at a fixed wavelength, and (2) dual-wavelength differential absorption with two rapidly-alternating wavelengths. The tunable laser light is produced using difference frequency generation by combining two near-infrared diode lasers in a periodically poled lithium niobate crystal, providing a continuous-wave (cw), room temperature mid-IR source with the low intensity noise, and rapid wavelength tunability typical of telecommunications diode lasers. Direct absorption measurements of MCH with a wavelength of 3413.7 nm demonstrate fast time response (1 μs) and low noise in cell (300-675 K) and shock tube (650-1450 K) experiments. The detection limits of MCH range from 0.5 ppm-m at 300 K to 11 ppm-m at 1440 K (pressure = 101 kPa). Next, time-division multiplexing is used to alternately generate two mid-IR wavelengths at 20 kHz, enabling the use of dual-wavelength differential absorption to eliminate interference absorption. Measurements of MCH concentration are first made in a cell, with varying amounts of n-heptane interference absorption. Accurate values of MCH concentration are obtained for n-heptane/MCH ratios as high as 15, demonstrating the utility of this sensor for species-specific hydrocarbon detection in systems with interfering absorption. Finally, time-resolved n-dodecane vapor concentration measurements are made in a shock-heated evaporating aerosol. The dual-wavelength differential absorption diagnostic is sensitive only to the vapor concentration, rejecting droplet extinction. These measurements illustrate the power of the differential absorption strategy for sensitive vapor-phase detection in the presence of particle scattering. The tunability of this new source will allow these concepts to be extended to other hydrocarbon fuels.     

Three-stage auto-ignition of n-heptane and methyl-cyclohexane mixtures at lean conditions in a flat piston rapid compression machine

One approach to enhancing the thermal efficiency of combustion systems is to burn fuels at ultra-lean conditions (equivalence ratio below 0.5). It has been recently reported that the auto-ignition of some hydrocarbon fuels, under specific temperature, pressure, and mixture conditions, releases heat in three distinctive stages. The three auto-ignition stages can be divided as a first low-temperature auto-ignition stage with conventional low temperature, and a high-temperature stage separated into two sub-stages. This study presents ignition delay time measurements of n-heptane and methyl-cyclohexane (MCH) mixtures in a flat piston rapid compression machine (RCM) under ultra-lean conditions. It provides experimental evidence of three-stage auto-ignition. This phenomenon of delayed high-temperature heat release is seldom reported in the literature and this is the first time to be reported for these types of fuels. The experiments cover two binary n-heptane/MCH mixtures of 15/85 and 70/30 by volume, pressures of 11 bar and 16 bar, temperature range of 700 to 900 K, and equivalence ratio of 0.4. The RCM optical access was utilized for high-speed chemiluminescence imaging. Detailed chemical kinetic simulations in a homogenous batch reactor with variable volume were conducted to further interrogate the three-stage auto-ignition phenomenon. Chemiluminescence shows that three-stage auto-ignition occurs in the adiabatically compressed end-gas, which indicates that this phenomenon is chemically-driven and is not induced by a thermal stratification in the RCM experiments. The model predicts the features of three-stage auto-ignition, which were experimentally observed at temperatures approximately below 750 K. As expected, significant discrepancies are observed in the ignition delays of experiment and simulation in the negative temperature coefficient (NTC) region. The simulation of the n-heptane/MCH 70/30 mixture shows better agreement with experiments in the Positive Temperature Coefficient (PTC) region compared to the 15/85 mixture.     

Diluting thiol-derivatized oligonucleotide monolayers on Au(1 1 1) by mercaptohexanol replacement reaction

Surface replacement reaction of thiol-derivatized, single-stranded oligonucleotide (HS-ssDNA) by mercaptohexanol (MCH) is investigated in order to reduce surface density of the HS-ssDNA adsorbed to Au(1 1 1) surface. Cyclic voltammograms (CVs) and scanning tunneling microscopy (STM) are employed to assess the composition and state of these mixed monolayers. It is found that each CV of mixed self-assembled monolayers (SAMs) only shows a single reductive desorption peak, which suggests that the resulted, mixed SAMs do not form discernable phase-separated domains. The peak potential gradually shifts to negative direction and the peak area increases step by step over the whole replacement process. By analyzing these peak areas, it is concluded that two MCH molecules will replace one HS-ssDNA molecule and relative coverage can also be estimated as a function of exposing time. The possible mechanism of the replacement reaction is also proposed. The DNA surface density exponentially reduces with the exposing time increasing, in other words, the replacement reaction is very fast in the first several hours and then gradually slows down. Moreover, the morphological change in the process is also followed by STM.     

傅里叶变换红外光谱结合衰减全反射技术用于地贫筛查指标的无试剂定量分析

利用傅里叶变换红外光谱(FTIR)和衰减全反射(ATR)结合偏最小二乘(PLS)回归,建立地中海贫血(地贫)筛查指标平均红细胞血红蛋白含量(MCH)、平均红细胞体积(MCV)和总血红蛋白(Hb)的同时定量分析方法。收集人外周血样品380个,根据地贫血液学指标筛查标准,地贫阳性180个、阴性200个。从全体样品中随机选取150个为检验集(阴性64,阳性86),余下230个为建模集(阴性136、阳性94);再将建模集随机划分为定标集(阴性68、阳性47,共计115)、预测集(阴性68、阳性47,共计115),共200次。实验比较的结果表明,中红外指纹区(1 600～900 cm-1)PLS模型的预测效果显著优于全扫描谱区(4 000～600 cm-1)PLS模型,并且模型复杂性明显降低。基于中红外指纹区PLS模型,MCH,MCV,Hb最优PLS因子个数分别为10, 10, 6;建模预测均方根误差(M_SEP_Ave)分别为2.19 pg,5.13 fL,8.0 g·L-1;建模预测相关系数(M_R_{P, Ave})分别为0.902,0.898,0.922;检验预测均方根误差(V_SEP)分别为2.22 pg,5.38 fL,7.7 g·L-1;检验预测相关系数(V_R_P)分别为0.900,0.895,0.929;地贫筛查灵敏度、特异性分别达到100.0%和95.3%。结论：FTIR/ATR光谱结合PLS方法可以提供一种无需试剂、快速简便的大人群地贫筛查新技术。     

Exploring the pyrolysis chemistry of 1,3,5-trimethylcyclohexane with insight into fuel isomeric and multiple substitution effects

To reveal insights into the combustion mechanism of multiple alkyl substituent cycloparaffins, this work reports an experimental and modeling study of 1,3,5-trimethylcyclohexane (T135MCH) pyrolysis in an extended flow reactor at low and atmospheric pressures. More than 30 species were detected and quantified employing synchrotron vacuum ultraviolet photoionization molecular beam mass spectrometry, and a detailed kinetic model developed based on reaction classes and update kinetic data was validated against the measured species profiles with a reasonable agreement. The reaction flux analyses were performed to reveal the key pathways of the fuel decomposition, intermediates production and aromatics formation. For the primary decomposition, the branching ratios of reaction types show strong dependence on changes of pressures and temperatures, including unimolecular methyl elimination, unimolecular ring-opening isomerization and H-abstraction. Besides the direct dissociation channels, major intermediate hydrocarbons are formed via stepwise dehydrogenation, recombination with ĊH₃ radical or “formally direct” chemically activated reactions triggered by Ḣ atom addition. Monocyclic aromatic hydrocarbons such as benzene and toluene can be produced by traditional H-abstraction/β-C-H scission sequence, cyclopentadiene-related pathways, or recombination mechanism from small linear products. The formations of indene and naphthalene are controlled by C₅+C₅ and C₅+C₄ mechanism respectively. The comparison work of species profiles combined with theoretical calculations of bond dissociation enthalpies (BDEs) was performed to reveal the multiple CH₃-group substituent and isomeric effects of methylcyclohexane (MCH), 1,2,4-trimethylcyclohexane (T124MCH) and T135MCH on pyrolysis activity and ethylene/benzene formation. Besides the increased reaction active sites, the added CH₃-group and ortho-substitution can both weaken the strength of CC and CH bonds, leading to the promoting decomposition activity. The different formation tendencies of products are caused by different BDEs, length of carbon skeleton, as well as complex fuel-specific pathways.     

Modeling and experimental investigation of methylcyclohexane ignition in a rapid compression machine

A new chemical kinetic reaction mechanism has been developed for the oxidation of methylcyclohexane (MCH), combining a new low temperature mechanism with a recently developed high temperature mechanism. Predictions from this kinetic model are compared with new experimentally measured ignition delay times from a rapid compression machine. Computed results were found to be particularly sensitive to isomerization rates of methylcyclohexylperoxy radicals. Three different methods were used to estimate rate constants for these isomerization reactions. Rate constants based on comparable alkylperoxy radical isomerizations corrected for the differences in the structure of MCH and the respective alkane, predicted ignition delay times in very poor agreement with the experimental results. The most significant drawback was the complete absence of a region of negative temperature coefficient (NTC) in the model results using this method, although a prominent NTC region was observed experimentally. Alternative estimates of the isomerization reaction rate constants, based on the results from previous experimental studies of low temperature cyclohexane oxidation, provided much better agreement with the present experiments, including the pronounced NTC behavior. The most important feature of the resulting methylcyclohexylperoxy radical isomerization reaction analysis was found to be the relative rates of isomerizations that proceed through 5-, 6-, and 7-membered transition state ring structures and their different impacts on the chain branching behavior of the overall mechanism. Theoretical implications of these results are discussed, with particular attention paid to how intramolecular H atom transfer reactions are influenced by the differences between linear alkane and cycloalkane structures.     

用MCH方法研究库仑屏蔽势的高角动量能谱

以库仑屏蔽势为模型,用蒙特卡罗哈密顿方法对库仑屏蔽势束缚态进行研究,并把结果和传统的数值解一维薛定谔方程的方法相比较,在基态或激发态,都得出相一致的结果.     

原子吸收光谱法检测血清铁、红细胞内铁及血清铁蛋白、 MCH、MCHC含量与老年冠心病、高血压病关系的研究

应用原子吸收光谱法检测了老年高血压、冠心病患者血清铁、红细胞内铁及血清铁蛋白、ＭＣＨ、ＭＣＨＣ。发现老年冠心病患者血清铁、红细胞内铁、血清铁蛋白含量明显高于对照组（Ｐ＜０．０１）。老年高血压患者血清铁蛋白、红细胞内铁、ＭＣＨ、ＭＣＨＣ也明显高于对照组（Ｐ＜０．０１）,血清铁与对照组比较有显著性差异（Ｐ＜０．０５）。结果表明：老年高血压,冠心病患者存在铁代谢异常,其游离铁与储存铁的增加可能是其发病的危险因素之一。