Interfacial Self-assembly of Chiral Selenide Nanomembrane for Enantiospecific Recognition

Here, we report the synthesis of chiral selenium nanoparticles (NPs) using cysteine and the interfacial assembly strategy to generate a self-assembled nanomembrane on a large-scale with controllable morphology and handedness. The selenide (Se) NPs exhibited circular dichroism (CD) bands in the ultraviolet and visible region with a maximum intensity of 39.96 mdeg at 388 nm and optical anisotropy factors (g-factors) of up to 0.0013 while a self-assembled monolayer nanomembrane exhibited symmetrical CD approaching 72.8 mdeg at 391 nm and g-factors up to 0.0034. Analysis showed that a photocurrent of 20.97±1.55 nA was generated by the D-nanomembrane when irradiated under light while the L-nanomembrane generated a photocurrent of 20.58±1.36 nA. Owing to the asymmetric intensity of the photocurrent with respect to the handedness of the nanomembrane, an ultrasensitive recognition of enantioselective kynurenine (Kyn) was achieved by the ten-layer (10L) D-nanomembrane exhibiting a photocurrent for L-kynurenine (L-Kyn) that was 8.64-fold lower than that of D-Kyn, with a limit of detection (LOD) of 0.0074 nM for the L-Kyn, which was attributed to stronger affinity between L-Kyn and D-Se NPs. Noticeably, the chiral Se nanomembrane precisely distinguished L-Kyn in serum and cerebrospinal fluid samples from Alzheimer's disease patients and healthy subjects.     

AN INSTRUMENT FOR SIMULTANEOUS ACQUISITION OF FLUORESCENCE SPECTRA AND FLUORESCENCE LIFETIMES FROM SINGLE CELLS

Abstract— An instrument is described that has the capability of acquiring both the spectrum and lifetime(s) of fluorescent species dispersed in biological cells. It operates at the single cell (or organelle) level and the spectral and temporal data collection can be performed simultaneously. A synchronously pumped, mode-locked dye laser provides the excitation light, time-correlated single-photon counting is used for lifetime measurements, and a diode array spectrograph is used for spectral work. Spatial resolution of sub-micrometer is obtained using a fluorescence microscope. The temporal resolution is better than 300 ps and wavelength resolution is less than 1 nm per channel. The instrument has been used for observing the spectral and temporal characteristics of hematoporphyrin in mouse myeloma cells.     

钯(Ⅱ)催化CO/乙烯交替共聚溶剂效应的研究

利用小釜实验考察了在多种新溶剂中钯（Ⅱ）催化ＣＯ／乙烯共聚制备聚酮高分子的反应，并利用高分辨核磁共振１Ｈ ＮＭＲ、１３Ｃ ＮＭＲ技术对在不同溶剂中制得产品的主链和端基进行了分析，实验结果表明除甲醇外，在丙酮、丙醛、Ｎ，Ｎ 二甲基甲酰胺、Ｎ，Ｎ 二甲基乙酰胺、冰乙酸、二甲基亚砜等溶剂中，钯（Ⅱ） 双膦催化剂仍具有较好的催化活性，尤其以冰乙酸为溶剂，在没有强酸阴离子存在的条件下，催化反应亦可顺利进行．实验结果同时表明适宜的溶剂除作为稀释剂外，还对中心金属钯（Ⅱ）具有适宜的稳定作用．产品端基分析结果表明在非醇类溶剂中共聚反应由乙烯插入Ｐｄ Ｈ键引发，在醇类溶剂中共聚反应主要由ＣＯ插入Ｐｄ ＯＲ键引发．     

THE FLUORESCENCE EXCITATION SPECTRUM OF QUININE BISULFATE

Abstract— A new measurement of the fluorescence excitation spectrum of chromatographically homogeneous quinine bisulfate has been made using a spectrometer offering high resolution and high sensitivity. Comparison of this spectrum with the absorption spectrum of the compound indicates that its quantum yield is independent of the wave number of the exciting light within ± 5 per cent for 2.57 μ^-l v 5.0μ^-1.     

Optical‐Resolution Photoacoustic Microscopy for Volumetric and Spectral Analysis of Histological and Immunochemical Samples

Optical‐resolution photoacoustic microscopy (OR‐PAM) is an imaging modality with superb penetration depth and excellent absorption contrast. Here we demonstrate, for the first time, that this technique can advance quantitative analysis of conventional chromogenic histochemistry. Because OR‐PAM can quantify the absorption contrast at different wavelengths, it is feasible to spectrally resolve the specific biomolecules involved in a staining color. Furthermore, the tomographic capability of OR‐PAM allows for noninvasive volumetric imaging of a thick sample without microtoming it. By immunostaining the sample with different chromogenic agents, we further demonstrated the ability of OR‐PAM to resolve different types of cells in a coculture sample with imaging depths up to 1 mm. Taken together, the integration of OR‐PAM with (immuno)histochemistry offers a simple and versatile technique with broad applications in cell biology, pathology, tissue engineering, and related biomedical studies.     

有机光导液晶光阀(透射式)及其性能的研究

本文报道用聚乙烯咔唑-2,4,7三硝基芴酮电荷转移复合物作光导层,与向列型及胆甾向列型混合液晶组成的夹心池结构制成的扭曲场效应、相变存储效应及动态存储效应三种直流透射式光阀及其性能的研究结果。制得的光阀均有明显开关效应。此外,还详细研究了扭曲场效应液晶光阀的阈值电压、对比度及上升时间与写入光功率的依赖关系。用白光写入,He-Ne激光读出,在扭曲场效应光阀上可实现非相干光-相干光转换,得到图象。用MTF法测得的光阀分辨率为34lps/mm。     

聚(肉桂酸乙烯基氧乙酯)的合成与表征

本文报道的是一种聚(肉桂酸乙烯基氧乙酯)负性光致抗蚀剂。它具有分辨力和灵敏度高、粘附性强、显影后很少产生皱胶、针孔罕见、贮存稳定和等离子去胶效果好等优异性能。在-75℃的温度下,向肉桂酸乙烯基氧乙酯单体中注入三氟化硼乙醚引发剂即可发生阳离子聚合,制得聚(肉桂酸乙烯基氧乙酯)。使用精制单体和助催化剂,在低温条件下,可合成出高分子量和高聚合产率的聚(肉桂酸乙烯基氧乙酯)。通过分级试样的光散射和粘度测定确立了相应的Mark-Houwink方程. 这种负胶的光刻最细条宽为0.5μm,适用于1-1.5μm以上条宽的生产工艺。     

变径毛细管柱GC／FTIR联用技术的研究

本文介绍了使用新型变径毛细管柱的气相色谱/傅里叶变换红外光谱联用技术(GC/FTIR)。以正构烷烃的混合物为样品,研究了载气速流、色谱进样量及柱后死体积对联用效果的影响。分别在变径毛细管柱GC/FTIR和普通毛细管柱GC/FTIR联用系统上分析了烷烃芳烃混合物和合成汽油样品,并利用软件系统提供的程序和红外标准谱库对所得光谱进行了检索。实验结果表明,变径毛细管柱GC/FTIR系统具有色谱进样量大,可鉴定组分多,分离能力强和检测灵敏度高等显著优点。     

Construction of nanosecond and picosecond pulse radiolysis system with supercontinuum probe

Supercontinuum (SC) with photonic crystal fiber (PCF) is a new technique of pulsed white light generation. The pump beam and the white probe light are necessary for pump–probe pulse radiolysis. The improvement of pulse radiolysis system can be expected by using PCF based SC as probe light. The source size of white light that depends on core size of PCF will be improved. Nanosecond time resolution pulse radiolysis with SC probe was successfully conducted about pure water sample. The absorption decay and spectrum of hydrated electron was obtained. As SC is a short pulse, it would be applicable for picosecond time resolution pulse radiolysis based on the stroboscopic method.     

AN IMPROVED HPLC METHOD FOR THE SEPARATION OF RETINALDEHYDE ISOMERS FROM VISUAL PIGMENTS

Abstract— A method for the analytical separation of retinal isomers such as 13- cis , 11- cis , 9- cis and all- trans retinal, dissolved in aqueous solutions of detergents, is described. The retinals are extracted by means of a non-isomerizing procedure and separated by HPLC on an octadecyl silane column used in normal phase. This column retains detergents without deteriorating and gives a satisfactory separation of retinal isomers with a resolution comparable with that obtained with silica gel column. The reliability of the method is verified by analysing the chromophore of visual pigment rhodopsin in digitonin solution, before and after irradiation with white light.     

High-performance liquid chromatography applications of optical rotation detection with compensation for scattering and absorbance at the laser wavelength.

Use of instrumentation developed to enable simultaneous monitoring of optical rotation (OR) and transmittance allows OR measurements to be made in the presence of high levels of absorbance, scattering or other effects that change the intensity of the plane-polarised light at the photodiode detector. This extends the application of OR detection to areas where it was previously difficult. Examples of the application of high-performance liquid chromatography (HPLC) with the improved OR detector include (i) the analytical scale separation of fructose and sucrose and (ii) the semi-preparative separation of enantiomers of warfarin and Tr?gers base. A signal-to-noise improvement of up to 150% is found when comparing signals with and without correction for transmittance changes. The improved OR detector has been used in series with a UV detector and the system shown to be suitable for on-line measurement of peak purity in separations using a chiral column under overload conditions.     

纳米分辨率的三维形貌检测仪

从光干涉方式，瞳窗关系和光源带宽等基本关系出发，利用空间不变系统理论解析了相移显微干涉检测系统中衍射效应的影响。为了减小横向分辨率对纵向分辨率的影响，利用相关信息提取或数字滤波的方法，获得了纳米分辨率的三维形貌。     

Conformer Pair Contributions to Optical Rotations in a Series of Chiral Linear Aliphatic Alcohols

The chain length effect of four chiral aliphatic alcohols,(S)-2-butanol,(S)-2-pentanol,(S)-2-hexanol and (S)-2-heptanol,on their specific optical rotations(OR)was studied experimentally and theoretically via quantum theory.Many conformations of each chiral alcohol exist as conformer pairs in solution.The OR sum from these pairs of conformers has much smaller contributions to OR values than that contributed by the most stable conformation. These four alcohols'OR values were also investigated using the matrix model,which employs each substituent's comprehensive mass,radii,electronegativity and symmetry number as the elements in the matrix.These are all particle properties.This matrix determinant is proportional to its OR values within a closely related structural series of chiral compounds.The experimental OR values and the matrix determinants of these four alcohols were compared with the predicted OR values obtained from quantum theory wave functions.The ORs predicted by the matrix method, which is based on particle function statistics,agreed with the results from quantum theory.The agreement between OR predictions by the matrix method and DFT calculations illustrates the wave-particle duality of polarized light that is operating in these predictions.     

利用扫描近场光学显微镜的偏振衬度对各向异性微晶的观察

利用扫描近场光学显微镜的偏振衬度对罗丹明6G的微晶进行观察,结果表明,用圆偏振入射光进行观察时,光学图像与表面形貌图有很好的对应关系。而用线偏振入射光进行观察时,随着入射偏振态的不同,成像差别较大:当偏振态方向沿着具有各向异性吸收的晶粒主吸收方向时,在垂直于主吸收方向上有很高的衬度,但图像分辨率较低;而入射偏振态垂直于主吸收方向时,衬度降低,分辨率提高;在与主吸收方向成45°角入射时,可以得到分辨率和衬度都比较好的图像。     

Time-Resolved Studies of Light Propagation in Crassula and Phaseolus Leaves

Abstract— Time-resolved transmittance was used to extract in vivo optical properties of leaves of green plants experimentally. In time-resolved transmittance measurements an ultrashort light pulse is directed onto the surface of the object and the transmitted light is measured with a time resolution in the range of picoseconds. A table-top terawatt laser was used to generate 200 fs light pulses at 790 nm with a repetition rate of 10 Hz. The light pulses were focused through a cuvette filled with water to produce white light pulses and optical filters were placed in the beam path to select the wavelength of the light focused onto the leaf surface. The time profiles of the light transmitted through the leaves was recorded with a streak camera having a time resolution of about 2.5 ps. Results from Crassula falcata and Phaseolus vulgaris studied at 550, 670 and 740 nm are reported. The three selected wavelength regions represent medium, high and a low absorption of light, respectively. A library of curves was generated using Monte Carlo simulation, and the absorption and scattering coefficients were extracted by comparison of experimental curves with this library. Our results suggest that in the case of the thin (200 μm) Phaseolus leaves and certainly in the case of the thick (4 mm) Crassula leaves, light scattering plays an important role in light transport through the leaf and should also affect light flux in these leaves.     

Effect of refraction index and thickness of the light guide in the position-sensitive gamma-ray detector using compact PS-PMTs

We constructed a position-sensitive gamma-ray detector consisting of an array of BGO scintillators, a light guide and compact PS-PMTs. The effects of refractive index and thickness of the light guide of a glass plate on the detector performance were investigated. A light guide with higher refractive index and smaller thickness is found better for a good spatial resolution.     

Heteroatom Dopants Promote Two‐Electron O2 Reduction for Photocatalytic Production of H2O2 on Polymeric Carbon Nitride

Polymeric carbon nitride modified with selected heteroatom dopants was prepared and used as a model photocatalyst to identify and understand the key mechanisms required for efficient photoproduction of H₂O₂ via selective oxygen reduction reaction (ORR). The photochemical production of H₂O₂ was achieved at a millimolar level per hour under visible‐light irradiation along with 100 % apparent quantum yield (in 360–450 nm region) and 96 % selectivity in an electrochemical system (0.1 V vs. RHE). Spectroscopic analysis in spatiotemporal resolution and theoretical calculations revealed that the synergistic association of alkali and sulfur dopants in the polymeric matrix promoted the interlayer charge separation and polarization of trapped electrons for preferable oxygen capture and reduction in ORR kinetics. This work highlights the key features that are responsible for controlling the photocatalytic activity and selectivity toward the two‐electron ORR, which should be the basis of further development of solar H₂O₂ production.     

PHOTOACTIVABLE FLUOROPHORES FOR THE MEASUREMENT OF FLUENCE IN TURBID MEDIA

Knowledge of the fluence distribution in biological tissue is essential for applications of lasers and light in medicine. A method using a photoactivable fluorophore as a chemical actinometer is presented to investigate the fluence (J/cm²) distribution in tissue-simulating phantoms. Such a chemical actinometer provides high spatial resolution (≤20 μm) while minimizing the disturbance of the fluence distribution. The actinometer substance, nonfluorescent in its native state, is incorporated into an acrylamide gel. Upon absorption of 351 nm radiation (λ_act), the actinometer substance becomes a Ruorophorc, which is excited at λ_ex≤ 485 nm. Thus the spatial distribution of the emitted fluorescence (λ_em≤ 515 nm) in the actinometer represents the fluence distribution of the activating radiation. Using histological techniques, 20 μm sections are cut from gel-like optical phantoms containing the actinometric substance. The fluorescence intensity in the section is recorded under a standard fluorescence microscope equipped with a sensitive video camera. To simulate different biological tissues, the scattering and absorption properties of the gel phantoms arc varicd over a wide range. The experimentally obtained fluence distributions are compared with theoretical models of light distribution in turbid media.     

Light scattering near and from interfaces using evanescent wave and ellipsometric light scattering

The broad range of interface light scattering investigations in recent years shows the power and the versatility of these techniques to address new and open questions in colloid and interface science and the soft condensed matter field. Structural information for polymers, liquid crystals, or colloids close to planar or spherical colloidal interfaces are either captured with long range light scattering resolution, or in a complementary approach by high resolution ellipsometric techniques. Of special interest is the dynamic behavior close to or in interfaces, since it determines material properties and responses to external fields. Due to the broad dynamical range and the high scattering contrast for visible light, interface light scattering is a key to elucidate soft matter interfacial dynamics. This contribution reviews experimental and related theoretical approaches for interface light scattering and further gives an overview of achievements based on such techniques.     

Resolution concept for separation of curium from californium by ion-exchange chromatography

Different factors affecting separation of the tervalent actinides curium and californium by ion-exchange chromatography are discussed in the light of the resolution factor. The fact that resolution is inversely proportional to resin particle diameter and directly proportional to column length has been confirmed experimentally. The effects influencing resolution due to changes in flow-rate of the mobile phase used are dependent on resin particle diameter. Changes in temperature affect a number of variables influencing resolution.