Field-amplified on-line sample stacking for determination of carnosine-related peptides by capillary electrophoresis

An on-line sample stacking method, namely field-amplified sample injection, has been developed for the separation and determination of carnosine, anserine, and homocarnosine by capillary electrophoresis. Using electrokinetic injection, about 130- to 160-fold improvement of sensitivity was achieved without loss of separation efficiency when compared to conventional sample injection. For conventional injection, the samples were dissolved in running buffer and then hydrodynamically injected for 10 s (3.45 kPa). Various parameters affecting separation and sample stacking were optimized. Under optimum conditions, linear responses were obtained over two orders of magnitude and the detection limits (defined as S/N = 3) of carnosine, anserine, and homocarnosine were 1.5 x 10(-8) to 1.6 x 10(-8) mol/L.     

AFLP在水稻线粒体DNA研究中的应用

对 Ａ Ｆ Ｌ Ｐ应用于水稻线粒体基因组研究中的问题进行了研究结果表明： Ａ Ｆ Ｌ Ｐ分析对ｍ ｔ Ｄ Ｎ Ａ 质量要求高,ｍ ｔ Ｄ Ｎ Ａ 应完整并反复抽提以达高纯度 ｍ ｔ Ｄ Ｎ Ａ 不完全酶切所造成的假阳性可经第二次酶切排除选择引物一个选择碱基最适合水稻ｍ ｔ Ｄ Ｎ Ａ Ａ Ｆ Ｌ Ｐ分析 另外,研究表明从银染后未经烘烤的新鲜银染凝胶回收的 Ｄ Ｎ Ａ 扩增效果好、产物经纯化可直接用于克隆以及探针标记     

Nonaqueous capillary electrophoresis for rapid and sensitive determination of fangchinoline and tetrandrine in radix Stephaniae tetrandrae and its medicinal preparations

A simple, rapid, and sensitive non-aqueous capillary electrophoresis procedure with head-column field-amplified sample stacking concentration for the analysis of fangchinoline and tetrandrine is established. Optimum separation and stacking conditions were obtained when the sample was injected at 8 kV for 50 s after preliminary pressure injection of ethanol (16.9 kPa) for 0.6 s and separated with the buffer containing 50 mM ammonium acetate, 0.5% (v/v) acetic acid, and 50% (v/v) acetonitrile in methanol medium at 24 kV applied voltage. The analytes were detected by UV at 214 nm. The two bisbenzylisoquinoline alkaloids can be separated within 6 min and quantified with high sensitivity. The detection limits were 0.30 ng mL(-1) for fangchinoline and 0.34 ng mL(-1) for tetrandrine, which indicated that the sensitivities were at least 1000-fold enhanced over those reported in the literature as obtained by UV detection. The method was applied to the analysis of fangchinoline and tetrandrine in Radix Stephaniae tetrandrae and its medicinal preparations with good results.     

Alq/DCM薄膜中的放大自发发射

自从在以 8-羟基喹啉铝 (Alq)掺杂小分子激光染料 DCM为激活介质的波导结构中 [1] ,光泵浦下观察到激光现象以来 ,这种以高效发光有机半导体材料代替以往的溶胶、凝胶或透明聚合物材料来稀释激光染料的方法 ,引起了人们广泛的关注和巨大的兴趣。因为 Alq的发射谱和 DCM的激发谱有很大的重叠 ,所以经光泵浦后的 Alq∶ DCM薄膜中处于激发态的 Alq分子很容易与附近的 DCM分子形成能量迁移[1] ,从而其发射谱表现为 DCM的荧光谱 ,而不是 Alq和 DCM的荧光谱的简单叠加。由于材料的发射谱相对于激发谱红移很大 ,所以很大程度上降低了材料…     

Effective Stimulated Emission Cross-Sections of Poly(Phenylene Vinylene) Copolymers in Toluene Solution

We report optical gain measurements in four different copolymers polyp-phenylene-co-[2,5-dioctyloxy-p-phenylene-bis-2(4-nonyl phenyl) vinylene]nonyl-PpPV, polym-phenylene-co-[2,5-dioctyloxy-p-phenylene-bis-2(4-methyl phenyl) vinylene]methyl-PmPV, polyp-phenylene-co-[2,5-dioctyloxy-p-phenylene-bis-2(4-methyl-phenyl) vinylene]methyl-PpPV, polyp-phenylene-co-[2,6-naphthylene-bis-2(4-nonyl phenyl) vinylene]nonyl-PpPV-NV in toluene. The copolymers are related to poly(phenylene vinylene) and have been synthesized via Horner–Emmons polycondensation reaction. The optical gain determined from the amplified spontaneous emission (ASE) intensity is dependent on the excited stripe length. The net optical gain coefficients are found to vary between 0.1 cm^–1 in nonyl-PpPV to 2.5 cm^–1 in methyl-PmPV under nanosecond pulse excitation. The gain for Rodamine 6G was also measured under the same experimental condition and was used to determine the stimulated emission cross-sections for the four polymers and found to be _SE(peak)= 6.7 × 10^–20 cm² for nonyl-PpPV, _SE(peak)= 1.7 × 10¹⁸ cm² for methyl-PmPV, _SE(peak)= 1.4 × 10^–18 cm² for methyl-PpPV, and _SE(peak)= 1.5 × 10^–18 cm² for nonyl-PpPV-NV.     

Perylene-Fused,Aggregation-Free Polycyclic Aromatic Hydrocarbons for Solution-Processed Distributed Feedback Lasers

Perylene-fused, aggregation-free polycyclic aromatic hydrocarbons with partial zigzag periphery ( ZY-01 , ZY-02 , and ZY-03 ) were synthesized. X-ray crystallographic analysis reveals that there is no intermolecular π–π stacking in any of the three molecules, and as a result, they show moderate-to-high photoluminescence quantum yield in both solution and in the solid state. They also display the characteristic absorption and emission spectra of perylene dyes. ZY-01 and ZY-02 with a nearly planar π-conjugated skeleton exhibit amplified spontaneous emission (ASE) when dispersed in polystyrene thin films. Solution-processed distributed feedback lasers have been fabricated using ZY-01 and ZY-02 as active gain materials, both showing narrow emission linewidth (<0.4 nm) at wavelengths around 515 and 570 nm, respectively. In contrast, ZY-03 did not show ASE and lasing, presumably due to its highly twisted backbone, which facilitates nonradiative internal conversion and intersystem crossing.     

Multicolor Amplified Spontaneous Emissions Based on Organic Polymorphs That Undergo Excited‐State Intramolecular Proton Transfer

Two polymorphs emitting near‐infrared ( 1 R form: α phase, λ_em=702 nm, Φ_f=0.41) and orange‐red fluorescence ( 1 O form: β phase, λ_em=618 nm, Φ_f=0.05) were synthesized by finely controlling the crystallization conditions of compound 1 , a structurally simple excited‐state intramolecular proton transfer (ESIPT)‐active molecule. Multicolor amplified spontaneous emissions (ASEs) were realized, for the first time, based on these polymorphs. Notably, the 1 O crystal underwent heating‐induced phase transformation from the β phase to the α form in a single‐crystal to single‐crystal (SCSC) manner accompanied with an unprecedented ASE changing. The ASE behavior of polymorphs 1 R , 1 O as well as the ASE changing during SCSC was investigated. The feasibility of multicolor lasing based on the present organic polymorphs was confirmed, which may provide a new development strategy for organic laser science and technology.     

Sensitive profiling of biogenic amines in human urine by capillary electrophoresis with field amplified sample injection

In order to monitor biogenic amines in human urine, a method based on field‐amplified sample injection combined with capillary electrophoresis and direct UV absorption detection was developed. Dopamine, tyramine, tryptamine, serotonin and epinephrine were effectively separated and identified in human urine samples, and detection limits were 0.072, 0.010, 0.027, 0.010 and 0.120 µmol/L, respectively. Detection limits comparable to laser‐induced fluorescence detection or solid phase extraction combined with capillary electrophoresis were achieved. Parameters affecting electrophoretic system detection sensitivity were investigated. Optimal separation conditions were obtained using as background electrolyte a pH 6.5 mixture of 2‐(morpholino)ethanesulfonic acid 20 mmol/L and 30 mmol/L phosphate buffer, containing 0.05% hydroxypropylcellulose and 10% v/v methanol. Injections of the sample solution were performed by applying a voltage of 12 kV for 50 s. Recovery and accuracy ranged between 89.4 and 94.9%, and 89 and 112%, respectively. The method was successfully applied on actual urine samples (from a healthy volunteer): target bioamine content was consistent with endogenous levels reported in the literature. The proposed method is simple, fast and inexpensive and can be conveniently employed in work‐related stress studies. The affordability and noninvasive sampling of the method allow epidemiological studies on large number of exposed persons to be performed. Copyright © 2013 John Wiley & Sons, Ltd.     

Ratiometric DNA Walking Machine for Accurate and Amplified Bioassay

DNA walking machines opened new avenues for the biosensing and demonstrated great success in the past few years. Since DNA machines are mainly nonequilibrium systems driven by dynamic interactions, the matrix effects on DNA machines is a bottleneck and more intricate than common DNA-mediated assays, especially for complicated physiological samples. Herein, to realize an accurate and reliable quantitative machine, a ratiometric DNA walking machine was developed in human serums and cell lysates based on the elemental isotope ratio measurement. The target DNA-triggered walking machine converted and amplified biological signals into mass spectrometric signal ratios (¹⁹⁷Au/¹¹⁵In) via a burnt-bridge mechanism. Under the optimized conditions, the limit of detection (LOD, 3σ) was 8 fM for target DNA, with a dynamic linear range of 0.05–0.7 pM. The ratiometric DNA walking machine was directly applied in human serum samples with satisfactory recoveries of 94 to 105 %, demonstrating an excellent stability and a high accuracy. Combining the aptamer-based specific recognition, the proposed DNA machine is expected to be a versatile platform for other targets, such as small biomolecules and proteins.     

The FEL SASE operation, bunch compression and the beam heater

We discuss the conditions required for an optimal SASE FEL operation when bunch compression techniques are exploited to enhance the bunch peak current. We discuss the case of velocity bunching and magnetic bunch compression. With reference to the latter technique we provide a quantitative estimate of the amount of laser heater power necessary to suppress the micro-bunching instability without creating any problem to the SASE dynamics.