记忆面包

"最新消息:XX食品公司:新研制出了一种能够刺激人脑记忆系统暂时性记忆的面包,它无任何副作用,可以使你迅速吸收面包上的信息,较长时期保持清楚记忆……"历史课上,我正在认真地抄老师写的板书,旁边的东雷轻轻地碰了碰我:"嘿,兄弟,写这些有什么用,考试前还得现背。"我对于东雷一贯有些稀奇古怪的念头已习以为常,因为我俩同样学习不好,但我自认为比他认真多了,只是脑子不太好使。见他一副怪模样。

多层介质膜的体吸收与界面吸收研究

以TiO_2/SiO_2膜系为例,报道了用横向光热偏转技术研究多层介质膜体、面吸收的实验方法与实验结果.文中对实验结果作了分析讨论并把它与文献报道的光声法作了比较.

800nm Semiconductor Absorber with Low Temp erature Method and Surface State Method Combined Absorber for Kerr Lens Modelocking of Ti:Al_2O_3 Laser

A novel 800nm Bragg mirror type of semiconductor saturable absorption mirror wit h low temperature method and surface state method combined absorber is presented .With which passive Kerr lens mode locking of Ti∶Al 2O 3 laser pumped by argo n ion laser is realized,which produces pulses as short as 40fs.The spectrum band width is 56nm,which means that it can support the modelocking of 20fs.The pulse frequency is 97.5MHz;average output power is 300mW at the pump power of 4.45W.

浅谈银行集资与股票集资的关系

银行集资和股票集资是相互联系,但又有区别的两种集资形式。其不同点集中表现在筹资和用资两个环节上。从筹资方面看,银行所吸收存款主要是个人、企业和机关的闲置货币和暂时不用的资金。一般来讲,这些货币资金有两个特点:一是时间短。存入银行的钱,大多是为了以后的消费和其他用途,真正为了取得银行利息而长期存入的是少数.因此,为了使用方便和灵活,人们一般愿意以活期和短期形式将货币存入银行。

离子束溅射Ta_2O_5薄膜光学性质的热处理研究

使用离子束溅射法,在熔融石英衬底上沉积Ta_2O_5薄膜,并将Ta_2O_5薄膜置入100℃到500℃的环境中退火.通过XRD、透过率光谱、面吸收测试,研究了热退火温度对Ta_2O_5薄膜折射率与面吸收的影响.总结了退火温度与薄膜折射率与面吸收的对应关系,并给出简单的理论解释.该结论对Ta_2O_5薄膜的制备及光学性能调控提供一定的参考价值.

Theoretical Studies on One-photon and Two-photon Absorption Properties of Pyrene-core Derivatives

The analytic response theory at density functional theory level is applied to investigate onephoton and two-photon absorption properties of a series of recently synthesized pyrene-core derivatives. The theoretical results show that there are a few charge-transfer states for each compound in the lower energy region. The one-photon absorption properties of the five investigated compounds are highly consistent with those given by experimental measurements. The two-photon absorption intensities of the compounds are greatly enhanced with the increments of the molecular sizes, in which the two-photon absorption cross section of the four-branched compound is about 5.6 times of that of the mono-branched molecule. Fhrthermore, it is shown that the two-photon absorption properties are sensitive to the geometrical arrangements.

电流调制下光注入VCSEL-SA的可重构逻辑运算

基于电流调制和光注入共同作用下的带有饱和吸收体的垂直腔面发射激光器(VCSEL-SA),提出了一种可重构的光电逻辑门(NOT,NAND,NOR,XOR),数值研究了电流调制下VCSEL-SA的spiking动力学特性,及电流调制下光注入VCSEL-SA的逻辑运算性能。研究结果表明,对于电流调制下的光注入VCSEL-SA,光电逻辑门可以在一定的偏置电流范围内实现。通过选取合适的调制电流,可以实现重构的逻辑运算(NAND,NOR),且两个调制信号之间的时延对逻辑运算性能影响较小。通过改变电流调制信号的输入方式并移除光注入信号,VCSEL-SA可以实现XOR逻辑运算。此外,基于电流调制下光注入VCSEL-SA的可重构逻辑运算对噪声有较好的容忍性。研究结果可为未来光子神经网络解决复杂的信号处理任务提供一定的理论基础。

液氮间接冷却双平晶单色器面吸收与体吸收的对比研究

针对高能同步辐射拟采用U35波荡器光源,用有限元软件对晶体单色器第一晶体着光面施加面功率密度和体功率密度分别进行数值模拟,给出晶体最高温和热变形去掉二次项和三次项后的高度误差和斜率误差,为高精度光源束线设计中单色器后面的热变形矫正装置提供参数要求。计算结果显示面吸收最高温和热变形去掉二次项和三次项后的斜率误差均大于体吸收结果,并且单色器热负荷利用体吸收进行模拟也更符合实际工况。

高功率密度激光辐照下镀膜镜片热变形的模拟和测量

为研究近红外高功率密度激光辐照下熔融石英镜片的热变形,基于有限元分析软件建立了镜片热力学模型并进行了计算分析,同时开展了实验测量。首先,建立了镀增透膜楔形石英镜片的有限元分析模型,得到了激光辐照下温度和形变量随时间的变化关系和镜体形变图像。其次,计算分析了楔镜体吸收率、膜层吸收率对热变形的影响,研究了不同功率密度和总功率的激光辐照时熔融石英镜片热变形的规律。最后,研究了镀增透膜石英楔镜在总功率为12 kW和最高功率密度为44 kW·cm^(-2)激光辐照下的温升和形变规律,并对实验和建模计算结果进行了分析,激光功率在5~15 kW范围时,面型计算值与实验测量值最大相对偏差约为6%。激光功率在2~15 kW范围时,温度计算值与实验测量值最大相对偏差约为8%。研究结果表明:热变形主要取决于膜层的吸收,楔镜的温升和形变量随膜层吸收和体吸收率呈准线性变化关系;膜层吸收和体吸收形变方向的不同可能造成面型凹坑。

Cavity Ring-Down Spectroscopy Measurements of Trace H_(2)S in SF_(6) and SF_(6)/N_(2) Mixture

H_(2)S is one of the most important characteristic decomposition components of SF_(6)insulated gas,and the detection of trace H_(2)S is significant for early fault diagnosis of gas insulated electrical equipment.A 1578 nm wavelength distributed feedback diode laser(DFB-DL)based cavity ring-down spectroscopy(CRDS)experimental platform is developed to monitor the concentrations of H_(2)S in SF_(6)and SF_(6)/N_(2)mixture carrier gas.The detection sensitivity is higher than 1×10^(-6).The absorption cross section parameterσis vital for calculating the concentration.With repeated experiments using standard gas samples,parameterσof H_(2)S in pure SF_(6)and SF_(6)/N_(2)mixture carrier with different mixing ratios is calibrated.Compared with the simulatedσvalues,the influence of carrier gas on the broadening of spectral profile is discussed.The variation of absorption cross sectionσwith different carrier gas mixing ratios is studied as well,so that the calculation of the concentration in the carrier gas of any mixing ratio is possible.Thus,the application of CRDS in trace component detection of gas insulated electrical equipment is promising.

Towards the Mechanism of Mass Transfer of a Single Bubble

This paper focuses on the mechanism of interfacial mass transfer of a single bubble, based on the chemical potential driving force, an approach for calculating interfacial concentration in practical process is proposed. The absorption processes of bubble under both quiescent and mobile conditions are analyzed and discussed respectively. For a stationary absorption, only in the case of liquid bulk concentration near saturated value, the interfacial concentration could close to the equilibrium value ; For a moving bubble, under ordinary operating condition （Yo〉l）, the interfacial concentration is far from its equilibrium. Only under bulk concentration near saturated value or a smaller Yo（Yo〈0.1） which may involve the complication of additional resistance at interface induced by surface contamination or surfactant added, the interfacial concentration could be approximate to equilibrium value. The interfacial concentration close to the interface on liquid side for a single CO2 bubble absorbed by methanol is measured using a modern optical instrumentation in which the laser holographic interference method is adopted with a real-time and amplification technique. Experimental results show that the interfacial concentration decreases significantly with increasing Re and is far from the equilibrium one in a larger Re range. Experiments validate the proposed model.

Influence of Integral Instability of Kramers-Kronig Transformation on Photoabsorption Cross Sections

The photoabsorption cross sections of condensed atoms and molecules have proven to be dependent not only on the imaginary parts but also on the real parts of the polarizabilities due to the strong interatomie interactions in condensed environment. The real parts of the polarizabilities calculated usually by using the famous Kramers-Kronig transformation （KKT） from the photoabsorption cross sections of the isolated atoms are very sensitive to the accuracy of the implementation method of the infinite integral in the KKT. The influence of the integral instability of the KKT and the real part of the polarizability on the variation of the photoabsorption cross sections with the number density and the structure of the condensed matter has been studied in the present work for the first time. The conclusion is that the integration method with interpolation has given more reasonable results than the direct truncation method if some appropriate interpolation functions have been used. Some notes and conclusions have also been given for the applications of the alternative coupled expressions of photoabsorption cross sections.

Effect of surfactant type on interfacial area and liquid mass transfer for CO_2 absorption in a bubble column

The effect of different surfactants(n-octyltrimethylammonium bromide(OTABr),sodium dodecyl benzene sulfonate(SDBS) and Tween 80) with different critical micelle concentrations(CMC) on the CO_2 absorption into aqueous solutions in a bubble column is analyzed in the present work.The presence of these surfactants increased the gas-liquid interfacial area,and decreased the liquid phase mass transfer coefficient,but with significant different extent.The results indicated that the CMC can be a key parameter affecting the mass transfer of CO_2 absorption into a dilute aqueous solution of a surfactant.Sardeing's model was used to fit the experimental data successfully by re-correlating the parameters.

Effect of organic depressant lignosulfonate calcium on separation of chalcopyrite from pyrite

In order to selectively separate chalcopyrite from pyrite,the effect of organic depressant lignosulfonate calcium(LSC) on the flotation separation of chalcopyrite from pyrite was investigated by flotation tests. The depression mechanism was studied by Fourier-transform-infrared(FTIR) analysis. The flotation tests of single mineral show that LSC can depress the flotation of pyrite in a certain pH range,but it has little effect on chalcopyrite flotation. Flotation separation of a mixture of chalcopyrite and pyrite can be completed to obtain a copper concentrate grade up to 24.73% with a recovery of 80.36%. IR analysis shows that LSC and butyl xanthate compete in absorption on pyrite surface,and there exists an LSC characteristic peak on pyrite surface. There is little adsorption of LSC on chalcopyrite.

Monte Carlo Simulation for the Adsorption of Symmetric Triblock Copolymers

The adsorption behavior of symmetric triblock copolymers, Am/2BnAm/2, from a nonselective solvent at solid-liquid interface has been studied by Monte Carlo simulations on a simple lattice model. Either segment A or segment B is attractive, while the other is non-attractive to the surface. Influences of the adsorption energy, bulk concentration, chain composition and chain length on the microstructure of adsorbed layers are presented. The results show that the total surface coverage and the adsorption amount increases monotonically as the bulk concentration increases. The larger the adsorption energy and the higher the fraction of adsorbing segments, the higher the total surface coverage is exhibited. The product of surface coverage and the proportion of non-attractive segments are nearly independent of the chain length, and the logarithm of the adsorption amount is a linear function of the reciprocal of the reduced temperature. When the adsorption energy is larger, the adsorption amount exhibits a maximum as the fraction of adsorbing segment increases. The adsorption isotherms of copolymers with different length of non-attractive segments can be mapped onto a single curve under given adsorption energy. The adsorption layer thickness decreases as the adsorption energy and the fraction of adsorbing segments increases, but it increases as the length of non-attractive segments increases. The tails mainly govern the adsorption layer thickness.

Growth and yield of rice as affected by transplanting dates and seedlings per hill under high temperature of Dera Ismail Khan, Pakistan

Studies were initiated for two consecutive years to find out the effect of time of transplanting and seedlings hill^-l on the productivity of rice in Dera Ismail Khan district of North West Frontier Province （NWFP）, Pakistan. The experiment was laid out in a randomized complete block design with split plot arrangements. Main plots consisted of four transplanting dates viz. 20th and 27th of June and 4th and 1 lth of July while sub-plots contained 1, 2, 3 or 4 seedlings hill^-1. Among transplanting dates, June 20th planted crop gave highest paddy yield and net return with I seedling hill^-1. It explains that the use of more seedlings hill^-1 not only adds to cost but is also a mere wastage of natural resources. Based on research findings, we conclude that the use of I seedling hill^-1 is most appropriate for timely sowing otherwise 4 seedlings hill^-1 should be used to compensate for the yield gap in late transplanted rice.

Heat transfer and nanofluid flow over a porous plate with radiation and slip boundary conditions

Presence of different terms with various values can alter the thermal behavior of the nanofluids flow over porous surfaces.The aim of this research is to study the influence of nanoparticles volume fraction,nanoparticles type,suction or injection,the heat generation or absorption,the Eckert number,thermal and velocity slip parameters,and radiation on the velocity and temperature fields on the flow and heat transfer over a porous flat plate.Four different types of nanoparticles including metal nanoparticles (Cu),metal oxide nanoparticles (Al2O3) and carbon-based nanomaterials (MWCNTs and SWCNTs) which were dispersed in the water (as based fluid) are studied.The governing equations are converted into the ordinary differential equations using similarity solution and solved numerically by the RKF45 algorithm.The results of the simulations showed a contradiction with the results of other researchers who expressed that using nanoparticles with higher thermal conductivity and volume fraction led to increasing heat transfer rate in nanofluids;this study proves that,in some cases,boosting the volume fraction of nanoparticles has a potential to decrease the heat transfer rate due to significant changes in values of some parameters including radiation,heat generation,and viscous dissipation.

Effect of Substitution Site on Two-Photon Absorption and Excited States Properties of Lipid Droplets Detection NAPBr Dyes:a Theoretical Perspective

Two-photon fluorescence dyes have shown promising applications in biomedical imaging.However,the substitution site effect on geometric structures and photophysical properties of fluorescence dyes is rarely illustrated in detail.In this work,a series of new lipid droplets detection dyes are designed and studied,molecular optical properties and non-radiative transitions are analyzed.The intramolecular weak interaction and electron-hole analysis reveal its inner mechanisms.All dyes are proven to possess excellent photophysical properties with high fluorescence quantum efficiency and large stokes shift as well as remarkable two-photon absorption cross section.Our work reasonably elucidates the experimental measurements and the effects of substitution site on two-photon absorption and excited states properties of lipid droplets detection NAPBr dyes are highlighted,which could provide a theoretical perspective for designing efficient organic dyes for lipid droplets detection in biology and medicine fields.

x_F(or y)-Dependence of Nuclecir Absorption and Energy Loss Effects on J/ψ Production

By means of the nuclear parton distribution studied only with lepton deep-inelastic scattering experimental data, the J/ψ ＂normal nuclear absorption＂ and energy loss effects are studied in a GIauber formalism at HERA and RHIC energies. Assuming that the absorption cross section σabs increases with the charmonium-nucleon center of mass energy, the results reveal a significant dependence of the aabs on rapidity g at RHIC energies. The initial-state energy loss effect, which is found important only at HERA energies, is also considered, and its influence should be eliminated when we studied the absorption effect at low collision energies. Finally, we also present the theoretical prediction for LHC.