Optimum design of photoresist thickness for 90-nm critical dimension based on ArF laser lithography

In this work,a 90-nm critical dimension(CD) technological process in an ArF laser lithography system is simulated,and the swing curves of the CD linewidth changing with photoresist thickness are obtained in the absence and presence of bottom antireflection coating(BARC).By analysing the simulation result,it can be found that in the absence of BARC the CD swing curve effect is much bigger than that in the presence of BARC.So,the BARC should be needed for the 90-nm CD manufacture.The optimum resist thickness for 90-nm CD in the presence of BARC is obtained,and the optimizing process in this work can be used for reference in practice.     

Enhanced circular dichroism of plasmonic system in the strong coupling regime

The circular dichroism(CD) signal of a molecule is usually weak,however,a strong CD signal in optical spectrum is desirable because of its wide range of applications in biosensing,chiral photo detection,and chiral catalysis.In this work,we show that a strong chiral response can be obtained in a hybridized system consisting of an artificial chiral molecule and a nanorod in the strong coupling regime.The artificial chiral molecule is composed of six quantum dots in a helix assembly,and its CD signal arises from internal Coulomb interactions between quantum dots.The CD signal of the hybridized system is highly dependent on the Coulomb interactions and the strong coupling progress through the electromagnetic interactions.We use the coupled oscillator model to analyze strong coupling phenomenon and address that the strong coupling progress can amplify the CD signal.This work provides a scenario for designing new plasmonic nanostructures with a strong chiral optical response.     

Aggregation Behavior of pHLIP in Aqueous Solution at Low Concentrations: A Fluorescence Study

pH (low) insertion peptide (pHLIP) is a 36-residue peptide derived from the third transmembrane helix of the membrane protein bacteriorhodopsin. The hydrophobicity of this peptide makes it prone to aggregation even at low concentrations, but this has not been studied in detail. In this work, we characterized monomeric and aggregated forms of pHLIP in aqueous solution (pH 8) at low concentrations (~μM) using fluorescence-based approaches, complemented by circular dichroism (CD) spectroscopy. We show here that monomeric and aggregated pHLIP display differential red edge excitation shift (REES) and CD spectra. These spectroscopic features allowed us to show that pHLIP aggregates even at low concentrations. A detailed knowledge of the aggregation behavior of pHLIP under these conditions will be useful for monitoring and quantifying its interaction with membranes.     

Artifactual circular dichroism effect in a photoelastic modulator

The three-intensity technique is used to calibrate a photoelastic modulator by its temporal waveform. This method not only allows us to measure the intrinsic static phase retardation and modulation amplitude but also provides the evidence for the existence of circular dichroism (CD) in the photoelastic modulator. In this report, we will demonstrate the averaged intensity for normalization in this PEM modulated light not only depicts a periodic modulation, it also exhibits anti-symmetric distributions at P = 45° and P = −45°, which was considered as constant for conventional PEM ellipsometry. Four models were examined to verify that only a circular dichroism medium coupled with the periodical induced birefringence modulator can explain the phenomena. This work can quantitatively measure the artifactual CD effect of PEM and reduce its system error in CD spectrometer which consists of a PEM.     

Precipitate growth in concentrated binary alloys: a comparison between kinetic Monte Carlo simulations,cluster dynamics and the classical theory

The numerical modelling of concentrated alloy precipitation kinetics remains a challenge at all scales. At the microscopic scale, kinetic Monte Carlo (KMC) simulations can cope with nucleation and early growth whatever the solute concentration may be; it cannot, however, address coarsening. At the mesoscopic scale, the advantage of cluster dynamics (CD) is its ability to describe the whole kinetics of precipitation but lacks of reliability for nucleation in concentrated alloys. Finally, analytical models are preferred at the macroscopic scale for their simplicity, their flexibility and their ability to be incorporated within more general approaches, to predict mechanical properties, for instance. The present work aims at examining the ability of CD and classical analytical models to describe the growth of an isolated precipitate in a concentrated binary alloy, by comparison with KMC simulations taken as the reference.     

Transport of a Cancer Chemopreventive Polyphenol,Resveratrol: Interaction with Serum Albumin and Hemoglobin

Resveratrol is a natural phytoalexin with pharmacologic effects on several human diseases: carcinogenesis, coronary heart disease and neurodegenerative disease. Due to its poor water solubility, resveratrol must be bound to proteins to keep it at a high concentration in serum. In our work, the bindings of resveratrol to plasma proteins, human serum albumin (HSA) and hemoglobin (Hb), have been investigated systematically by fluorescence quenching technique, synchronous fluorescence, UV–vis absorption spectroscopy, circular dichroism (CD) spectroscopy and molecular modeling method. The fluorescence data show that the binding of resveratrol to HSA or Hb is a static quenching procedure and each protein has only one binding site for the drug. The binding constant of resveratrol to HSA is larger than that of resveratrol to Hb at corresponding temperature, which indicates that the affinity of HSA toward the drug is higher than that of Hb. The CD spectroscopy indicates that the secondary structures of the proteins are changed in the presence of resveratrol with the reduction of α-helices, which decreased about 18.75% for HSA and 9.43% for Hb at the drug to proteins molar ratio of 2. Thermodynamic analysis and molecular modeling suggest that hydrophobic interaction plays a major role in the binding of resveratrol to HSA, and hydrogen bonding is the mainly binding force in the binding of resveratrol to Hb. The study of molecular modeling shows that resveratrol is located in the hydrophobic cavity between subdomain IB and IIA of HSA (the entrance of site I), or located in the central cavity of Hb (partial to the subunit A).     

S-和R-五味子丙素非对映异构体的圆二色谱研究

园二色谱(CD)是测定有机化合物绝对构型的常用方法。文章用圆二色谱仪对合成的4个联苯类化合物进行了表征(2个非桥键联苯化合物和2个桥键联苯化合物),得到两对几乎完全对称的圆二色谱谱图。根据其圆二色谱Cotton效应确定了4个化合物的联苯键的绝对构型。化合物3分别在256 nm出现负的Cotton效应,且在220 nm出现正的Cotton效应,表明这个化合物是S-构型;而化合物3’出现了相反的Cotton效应,表明这个化合物是S-构型。由化学相关法可以得知化合物2是R-构型, 化合物2’是R-构型。通过这些数据得出结论, 以S-噁唑啉为手性合成子的Ullmann反应得到的是S-构型联苯类化合物, 而以S-噁唑啉为手性合成子的Ullmann反应得到的是R-构型型联苯类化合物。     

Optimisation of the dipole-Coulomb approximation for high-l Rydberg states of polar molecules

ABSTRACT

The present work deals with the question of the origin choice to get the maximal accuracy of the dipole-Coulomb approximation in the theory of molecular Rydberg states with high orbital momentum l. Concerning birefringence in polar molecules, the question of adequate origin choice has first been raised in the classical work by Buckingham & Longuet-Higgins in 1968, where it has been taken into account that the dipole moment of a polar molecular core (cation) depends on the origin choice. This dependence also leads to inseparability of dipole and quadrupole corrections to the Rydberg electron spectra in polar molecules. In the present work a new option for the problem is proposed as applied to the dipole-Coulomb approximation. Considering a simplified model of a molecular core as a system of N effective fixed point charges, we show both analytically and numerically that the optimal choice of origin, at least for a linear core, is the geometric centre of the core. On the other hand, results of the present work as well as previous publications show that the problem raised by Buckingham and Longuet-Higgins does not have a universal solution.

Abbreviations: RS: Rydberg state; RSs: Rydberg states; ZEKE: zero electron kinetic energy; MATI: mass-analysed threshold ionisation; QDT: quantum defect theory; DCA: dipole-Couloumb approximation; CD: centre of dipole; CC: centre of charge; GC: geometric centre; DCAGC: dipole-Couloumb approximation with origin in the geometric centre; DCACD: dipole-Couloumb approximation with origin in the centre of dipole     

Metal–Graphene Hybrid Chiral Metamaterials for Tunable Circular Dichroism

In the field of optoelectronics, circular dichroism (CD) has caused great research interest because it is widely used in imaging and biosensing. A new method for dynamically controlling terahertz (THz) CD in metamaterials is proposed. By introducing chirality and graphene to metamaterials, a pair of chiral structures with completely opposite responses to left-handed circularly polarized (LCP) waves and right-handed circularly polarized (RCP) waves are designed. The influencing factors of CD are explored, including the gap of the structure, the linewidth of graphene, and the Fermi level of graphene. The largest CD (ΔR) is 77%. The CD can be actively modulated in a modulation range of 39–77% and the modulation depth is up to 38%. In addition, two-channel and four-channel chiral metasurfaces for near-field imaging are designed in this way. Good imaging effects and on (“1”) or off (“0”) effects of the multichannel metasurface are demonstrated. This work provides new ideas for the design of tunable metasurfaces and promotes the application of metasurfaces in THz dynamic imaging.     

双层开口环的圆二色性数值研究

基于琼斯矩阵的推导提出一种金属手性纳米结构-双层开口环阵列结构，其开口方向扭转一定角度以破坏对称性，并应用有限元方法研究圆二色性（CD）特性.研究表明：在左旋圆偏振光与右旋圆偏振光的激发下，该结构表现出巨大差异使得CD产生，其CD值达到0.34.结构的电流分布表明，在短波长处，上下层圆环的等效偶极子耦合可形成反键模式，在长波长处，上下层圆环的等效偶极子耦合可形成成键模式，研究结构参数对CD的影响.理解圆二色的物理机制，并提供一种设计手性结构的方法.     

Polarization mode dispersion and chromatic dispersion compensation by using a three-stage compensator

A three-stage compensator used for Polarization mode dispersion (PMD) and Chromatic dispersion (CD) compensation is proposed. The compensator is capable of compensating the two components of second-order PMD when no CD exists. Two operating points of compensating second-order PMD have been proposed. Two-stage and three-stage compensators are compared by the outage probability. When CD is introduced, the compensator should retain a quantity of second-order PMD to compensate CD. The outage probability when PMD and CD coexist has been calculated. The results show that a tradeoff must be made in order to compensate CD and PMD at the same time.     

Interaction of water‐soluble triphenylphosphines with β‐cyclodextrin: a quantum chemistry study

The interaction of β‐cyclodextrin (β‐CD) with meta‐trisulfonated triphenylphosphine derivatives bearing one or two methyl (or methoxy) groups on the aromatic rings has been investigated by PM3 calculations. The results show that phosphine molecules interact with β‐CD having either an unsubstituted sulfophenyl group or a substituted sulfophenyl group at the para and/or meta‐position. The presence of one methyl or methoxy group in the ortho‐position on each aromatic ring prevents the formation of an inclusion complex between meta‐trisulfonated triphenylphosphine derivatives and β‐CD. The deeply included phosphines in the β‐CD cavity show significant van der Waals interactions with β‐CD. These interactions are at the origin of the high association constants between these molecules and β‐CD. Phosphines exhibiting small association constants interact with β‐CD by forming H‐bonds and weak (or null) van der Waals interactions. Copyright © 2011 John Wiley & Sons, Ltd.     

Multi-band giant circular dichroism based on conjugated bilayer twisted-semicircle nanostructure at optical frequency

Plasmonic circular dichroism (CD) effect has been drawn great attention increasingly for its wide application in the fields of bio-sensing, biological detection, pharmaceuticals, and analytical chemistry. In this paper, we propose a chiral metasurface (CMS) to achieve strong multi-band CD effect at optical frequency. The designed CMS is composed of a periodic array of conjugated bilayer twisted-semicircle nanostructures. The numerical simulation results show that the CMS can produce strong multi-band CD effect due to the different coupling resonance modes under the excitations of left-handed circular polarization (LCP) light and right-handed circular polarization (RCP) light. It is shown that the chiral-selective absorption peaks can reach 89.4% and 95% for LCP light, 79% and 78.2% for RCP light, and the maximum CD is about 0.69 and −0.61 at 198.75 THz and 352.25 THz, 0.69 and −0.54 at 291.75 THz and 402.25 THz, respectively. The mechanism of the giant CD effect of the CSM has been revealed by analyzing the coupling mode of electric dipoles on the top and bottom layer through surface current distributions. Furthermore, the geometric parameter dependences of CD effect in the proposed CMS have been also studied numerically. The present results will guide the design of plasmonic chiral nanostructures for enhancing the CD effect.     

Interaction of different thiol-capped CdTe quantum dots with bovine serum albumin

Due to their unique optical properties, quantum dots (QDs) are rapidly revolutionizing many areas of medicine and biology. Despite the remarkable speed of development of nanoscience, relatively little is known about the interaction of nanoscale objects with organism. In this work, interaction of CdTe QDs coated with mercaptopropanoic acid (MPA), L-cysteine (L-cys), and glutathione (GSH) with bovine serum albumin (BSA) was investigated. Fluorescence (FL), UV–vis absorption, and circular dichroism (CD) spectra methods were used. The Stern-Volmer quenching constant (K_sv) at different temperatures, corresponding thermodynamic parameters (ΔH, ΔG and ΔS), and information of the structural features of BSA were gained. We found that QDs can effectively quench the FL of BSA in a ligand-dependent manner, electrostatic interactions play a major role in the binding reaction, and the nature of quenching is static, resulting in forming QDs-BSA complexes. The CD spectra showed that the secondary and tertiary structure of BSA was changed. This study contributes to a better understanding of the ligand effects on QDs-proteins interactions, which is a critical issue for the applications in vivo.     

对流项离散格式的对比与讨论

本文简单介绍了利用规正变量定义的各种对流项差分格式,给出了利用有限容积法离散粘性对流一扩散问题时的离散方程,其中的对流项采用高阶格式进行离散。以方腔顶盖驱动及圆管突扩区内层流流动考察了各种格式的计算精度与时效。通过对比分析得出:对于常规区域中的流动, QUICK、中心差分(CD)及SMART三种格式的精度与计算时效是比较合理的。     

Complexation of aminoglutethimide with native and modified cyclodextrins

Complexations of R(+) and RS(+/?)aminoglutethimide (AGT), the drug used in a treatment of breast and prostate cancer with native and modified cyclodextrins (α‐CD, β‐CD, γ‐CD, 2,6‐di‐O‐methyl‐β‐CD (DM‐β‐CD), 2,3,6‐tri‐O‐methyl‐β‐CD (TM‐β‐CD) and carboxymethyl‐β‐CD (CM‐β‐CD)) were studied. The stability constants were determined with UV–Vis spectrophotometric method at pH 9.0. The NMR data obtained for TM‐β‐CD suggest that the complexation of AGT is possible from both sides of CD molecule. This was confirmed by molecular dynamic simulations. Copyright © 2009 John Wiley & Sons, Ltd.     

Effects of cryopreservation with polyethylene glycol on the expression of CD11b and CD62L on the surface of polymorphonuclear leukocytes

In experimental and clinical studies, expression of surface adhesion molecules such as ?2-integrine (CD11b) and L-selectin (CD62L) on polymorphonuclear leukocyte (PMNL) are investigated to assess certain crucial innate immune functions. Because the expression of CD11b and CD62L on PMNL can alter they cannot be quantified reliably when the time between blood draw and measurements is prolonged. Goals of this study were to test effects of cryopreservation on the expression of CD11b and CD62L on human PMNLs either under native conditions as well as after stimulation-dependant adhesion molecules′ expression pattern. CD11b and CD62L expression on PMNL can be cryopreserved with 10% of PEG-solution for at least one month at -60 degree C. This was observed in native, unstimulated as well as in stimulated cell-preparations. CD11b is very stable in contrast to CD62L expression which appears to be more susceptible to alteration due to freezing-thawing. However, the relative stimulus-dependant changes of activation can still be reflected.     

Spectroscopic and Electrochemical Studies on the Interaction of Carmoisine Food Additive with Native Calf Thymus DNA

ABSTRACT

In this work, for the first time interaction between a carmoisine food additive and native calf thymus DNA was monitored using UV-Vis absorption, fluorescence, and circular dichroism (CD) spectroscopy, as well as cyclic voltammetry and viscosity measurements. It can be concluded that carmoisine could interact with DNA via a groove-binding mode as evidenced by a hyperchromic effect of absorption spectra, increases in the fluorescence quenching effect of DNA, certain induced CD spectral changes, and relatively small changes in the viscosity of DNA. The binding constants (K_b) for the carmoisine with DNA was estimated to be 6.2 × 10⁴ M^?1 through spectroscopic titrations. The cyclic voltammetry method showed that both anodic and cathodic peak currents of carmoisine decreased upon addition of the DNA. Circular dichroism spectra indicated that there are certain detectable conformational changes such as conversion from B-like to A-like in the DNA double helix when carmoisine was added.     

First observation of natural circular dichroism spectra in the extreme ultraviolet region using a polarizing undulator‐based optical system and its polarization characteristics

Natural circular dichroism (CD) spectra in the extreme ultraviolet (EUV) region down to a wavelength of 80 nm have been observed for the first time, using an alanine thin film deposited on sodium salicylate coated glass as a sample. Calibrated EUV‐CD spectra of l ‐alanine exhibited a large negative peak at around 120 nm and a positive CD signal below 90 nm, which were roughly predicted by theoretical calculations. A CD measurement system with an Onuki‐type polarizing undulator was used to obtain the EUV‐CD spectra. This CD system, the development of which took five years, can be used to observe even weak natural CD spectra. The polarization characteristics of this system were also evaluated in order to calibrate the recorded CD spectra.     

Particular features of circular dichroism spectra of resin-asphaltene compounds in solvent and crude oil

The circular dichroism (CD) spectra of solutions of asphaltenes, resins, and crude oils in toluene, as well as of oil residue, which is free of resin-asphaltene compounds (RACs), were studied in the spectral range 400–600 nm. It was demonstrated that, unlike, oil and RACs solutions, oil residue does not show the CD signal. This result proves that, in this spectral range, the occurrence of the CD signal in oil is determined by the presence of RACs. The concentration dependences of CD signal for the solutions under study were obtained for the maximum of the CD band in the considered spectral range. For pure toluene solutions of asphaltenes and resins, these dependences can be approximated with good accuracy by a linear function, whereas, for solutions of crude oils, the concentration curves deviate from the linear dependence at large concentrations of RACs due to the formation of particles of the disperse phase in oil. Therefore, in a certain concentration range, the structure of oil undergoes significant changes and becomes disperse, whereas solutions of molecules of RACs remain molecular.