核壳型二氧化硅色谱填料的研究进展

复杂样品的高效快速分离分析是分离科学家所面临的挑战。近年来,核壳型二氧化硅色谱填料以其高效、快速和低背压的特点被广泛用于小分子、大分子和复杂样品的快速分离分析。该文系统综述了二氧化硅核壳色谱固定相快速分离的机理,制备方法及其在小分子、多肽和生物大分子快速分离分析方面的应用,同时对核壳型色谱固定相的发展进行了展望。     

A novel algorithm based on visual saliency attention for localization and segmentation in rapidly-stained leukocyte images

In this paper, we propose a fast hierarchical framework of leukocyte localization and segmentation in rapidly-stained leukocyte images (RSLI) with complex backgrounds and varying illumination. The proposed framework contains two main steps. First, a nucleus saliency model based on average absolute difference is built, which locates each leukocyte precisely while effectively removes dyeing impurities and erythrocyte fragments. Secondly, two different schemes are presented for segmenting the nuclei and cytoplasm respectively. As for nuclei segmentation, to solve the overlap problem between leukocytes, we extract the nucleus lobes first and further group them. The lobes extraction is realized by the histogram-based contrast map and watershed segmentation, taking into account the saliency and similarity of nucleus color. Meanwhile, as for cytoplasm segmentation, to extract the blurry contour of the cytoplasm under instable illumination, we propose a cytoplasm enhancement based on tri-modal histogram specification, which specifically improves the contrast of cytoplasm while maintaining others. Then, the contour of cytoplasm is quickly obtained by extraction based on parameter-controlled adaptive attention window. Furthermore, the contour is corrected by concave points matching in order to solve the overlap between leukocytes and impurities. The experiments show the effectiveness of the proposed nucleus saliency model, which achieves average localization accuracy with F1-measure greater than 95%. In addition, the comparison of single leukocyte segmentation accuracy and running time has demonstrated that the proposed segmentation scheme outperforms the former approaches in RSLI.     

A potential green-emitting phosphor Ca8Mg(SiO4)4Cl2:Eu for white light emitting diodes prepared by sol-gel method

A potential green emitting phosphor Ca₈Mg(SiO₄)₄Cl₂:Eu²⁺ was prepared by modified sol-gel method. The factors those affect the photoluminescence intensity including heating temperature, the usage of the chlorine source CaCl₂ and the concentration of dopant Eu²⁺ were also investigated in detail. As comparison, the phosphor prepared by solid-state reaction was also prepared. The phosphors show intense absorption in the range of 375-450 nm, which makes it a potential candidate of green emitting phosphor used for near-UV or blue light excited white LEDs.     

Surface-modification of TiO2 with new metalloporphyrins and their photocatalytic activity in the degradation of 4-notrophenol

A new mono-functionalized porphyrin derivative, 5-mono-[4-(2-(4-hydroxy)-phenoxy)ethoxy]-10,15,20-triphenylporphyrin (3) and its Cu(II) (3a), Zn(II) (3b) and Ni(II) (3c) metalloporphyrins were synthesized and characterized by using various spectroscopic techniques. The corresponding 3a, 3b, 3c-TiO₂ photocatalysts were then prepared and characterized by means of FT-IR and diffused reflectance spectra, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic activities of 3a, 3b, 3c-TiO₂ were investigated by testing the photodegradation of 4-nitrophenol (4-NP) in aqueous solution under the halogen lamp irradiation. The results indicated that all the 3a, 3b, 3c enhanced the photocatalytic efficiency of bare TiO₂ in photodegrading the 4-NP, and 3a-TiO₂ exhibited the highest photocatalytic activity. The result is considered a combined action of potential match of 3a with TiO₂ CB and effective impregnated of 3a onto the surface of TiO₂.     

Photoluminescence of double-color-emitting phosphor Ca5(PO4)3Cl:Eu, Mn for near-UV LED

Eu²⁺ activated Ca₅(PO₄)₃Cl blue-emitting phosphors were prepared by the conventional solid state method using CaCl₂ as the chlorine source and H₃BO₃ as flux. The structure and luminescent properties of phosphors depend on the concentrations of Eu²⁺, the amount of CaCl₂ and the usage of the H₃BO₃ flux were investigated systematically. Eu²⁺ and Mn²⁺ Co-doped Ca₅(PO₄)₃Cl with blue and orange double-band emissions were also researched based on the optimal composition and synthesis conditions. The energy transfer between Eu²⁺ and Mn²⁺ was found in the phosphor Ca₅(PO₄)₃Cl:Eu²⁺, Mn²⁺, and the Co-doped phosphor can be efficiently excited by near-UV light, indicating that the phoshor is a potentional candidate for n-UV LED used phosphor.     

胡椒碱与牛血清白蛋白的相互作用

采用荧光光谱技术研究了胡椒碱与牛血清白蛋白（BSA）的相互作用。根据测定不同温度下胡椒碱对BSA的猝灭常数,证实了荧光猝灭过程为静态猝灭,由热力学参数焓变（ΔH）小于零和熵变（ΔS）大于零,推断出胡椒碱与BSA之间主要靠静电引力相结合,生成自由能变（ΔG）为负值,表明胡椒碱与BSA的作用过程是一个自发过程;并应用同步荧光光谱技术考察了胡椒碱对BSA构象的影响。     

Two identical conducting spheres with same potential in a uniform electric field

Interaction, polarization, and charges or electric field distribution of conducting spheres in applied electric field are in many fields including electrorheological fluids, electrophoresis, and electrical engineering. A system with two equipotential conducting spheres in an applied uniform electric field is analyzed by image method. A new method is put forward to calculate the image charges distribution when using image method, which ensures the validity of image method to analyze equipotential cases. An apparatus is constructed to measure the force experimentally as well. Results show that the distribution of electric field and electric interaction are different with the case not equipotential.     

A simple flow-injection chemiluminescence method for the determination of trace pentavalent vanadium in water samples

A simple method for rapid determination of trace pentavalent vanadium in natural water was presented by flow-injection chemiluminescence (CL). Through water injection, luminol and potassium permanganate were eluted from the anion exchange column to generate the CL, which was enhanced in the presence of V(V). Under the optimum conditions, the increased CL intensity was linear with V(V) concentration in the range from 0.1 to 100?ng?mL^?1. The limit of detection was 50?pg?mL^?1 (3σ) and the relative standard deviation (RSD) was 2.24% (n?=?5) for a 1.0?ng?mL^?1?V(V). At a flow rate of 2.0?mL?min^?1, one cycle of analysis could be performed in 0.5?min with a RSD of less than 3.0%. The proposed method was successfully applied to the determination of vanadium in natural water.     

N-（2,4-二氯苯基)-N′-(苯甲酰基)硫脲脱硫物合铜(Ⅱ)配合物的合成与晶体结构

在甲醇中由N-(2,4-二氯苯基)-N’-(苯甲酰基)硫脲(H2met)和CuCl2回流,合成了脱H2S的CuL2(HL=N-(苯甲酰基)-O-甲基-N’-(2,4-二氯苯基)假硫脲),其中HL由H2met脱硫得到。在室温条件下,采用缓慢挥发溶剂法培养出适合用于X射线衍射测试的单晶。由X单晶衍射确定了其晶体和分子结构,在配合物分子中,Cu(Ⅱ)与2个配体分子(HL)的N原子和2个羰基O原子发生配位,形成了2个六元螯合环[N(1A)—Cu—N(1)的键角为180.0°,O(1A)—Cu(1)—O(1)的键角为180.0°]组成的配合物。