A Competitor-switched Electrochemical Sensor for Detection of DNA

A competitor‐switched electrochemical sensor based on a generic displacement strategy was designed for DNA detection. In this strategy, an unmodified single‐stranded DNA (cDNA) completely complementary to the target DNA served as the molecular recognition element, while a hairpin DNA (hDNA) labeled with a ferrocene (Fc) and a thiol group at its terminals served as both the competitor element and the probe. This electrochemical sensor was fabricated by self‐assembling a dsDNA onto a gold electrode surface. The dsDNA was pre‐formed through the hybridization of Fc‐labeled hDNA and cDNA with their part complementary sequences. Initially, the labeled ferrocene in the dsDNA was far from surface of the electrode, the electrochemical sensor exhibited a "switch‐off" mode due to unfavorable electron transfer of Fc label. However, in the presence of target DNA, cDNA was released from hDNA by target DNA, the hairpin‐open hDNA restored its original hairpin structure and the ferrocene approached onto the electrode surface, thus the electrochemical sensor exhibited a "switch‐on" mode accompanying with a change in the current response. The experimental results showed that as low as 4.4×10⁻¹⁰ mol/L target DNA could be distinguishingly detected, and this method had obvious advantages such as facile operation, low cost and reagentless procedure.     

高粘度枯基酚甲醛树脂的固体酸催化法合成新工艺研究

以对枯基苯酚和甲醛为原料,运用正交实验法,经过固体酸(阳离子交换树脂)催化缩合、过滤、蒸馏等过程,研制出合成枯基酚甲醛树脂产品的一种新型工艺路线。产品外观为红棕色粘稠液体,pH值接近7,能够耐水和酸碱,稳定性好,主要用于电绝缘体、涂料和橡胶制品等领域。     

Delayed Fluorescent Emission from Pyrene Doped Phenanthrene Nanoparticles Based on Triplet-triplet Energy Transfer

Doped nanoparticles were prepared from pyrene and phenanthrene using a facile reprecipitation method. The doped nanoparticles presented unique delayed fluorescent emissions of pyrene under the unprotected condition. The ratio of the intensity of delayed fluorescence (I_DF) to that of phosphorescence (I_P) is about 4:1, which almost keeps unchanged with the decrease of pyrene content at room temperature. The intensity of the delayed fluorescence emissions is dependent on the relative content of pyrene, as well as the aggregation degree of nanoparticles. The delayed emissions are contributed to efficient triplet‐triplet energy transfer from phenanthrene (donor) to pyrene (acceptor). Steady fluorescence measurement have proved that the singlet‐singlet energy transfer process was also existent dominated by the radiation energy transfer mechanism.     

Facile synthesis of a melt-spinnable polyborazine from asymmetric alkylaminoborazine

<正>A novel asymmetric alkylaminoborazine monomer,2-propylamino-4,6-bis(methylamino)borazine,was synthesized for the first time,and directly polymerized to give a melt-spinnable polyborazine(PBN).This asymmetric alkylaminoborazine was synthesized by an aminolysis reaction of 2,4,6-trichloroborazine(TCB) with different amines under mild conditions.This route turns out to be much cheaper and simpler than the conventional routes.The chemical composition,structure,molecular weights and ceramic yield were investigated by EA,FTIR,NMR,GPC and TG analysis.The PBN exhibits suitable rheological property for melt-spinning, which suggests that it is a potential precursor for BN fibers.     

Two new homoisoflavanones from Polygonatum odoratum (Mill.) Druce

<正>Two new homoisoflavanones were isolated from the rhizomes of Polygonatum odoratum(Mill.) Druce and their structures were elucidated as(3R)-5,7-dihydroxy-8-methoxy-3-(4-methoxybenzyl)-6-methylchrom-an-4-one(1) and(3R)-5,7,8-trihydroxy-3-(4- hydroxybenzyl)-6-methylchroman-4-one(2),on the basis of spectral analysis.     

Synthesis and Cytotoxicity of Novel Diaryl Ureas Containing 2-Amino-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidinyl Group

<正>A series of 2-amino-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidinyl substituted diaryl urea derivatives was designed and synthesized.Their in vitro cytotoxicities against two cancer cell lines(Bel-7402 and A549) were evaluated by standard MTT assay.Six of tested compounds 6,8,10,17,21 and 22 exhibited more potent cytotoxicity superior to sorafenib.The structure activity relationship(SAR) study indicates that 2-amino-5,6,7,8-tetrahydropyrido- [4,3-d]pyrimidinyl group was an option for cytotoxic potency.     

Pyrolysis-GC/MS of Menthyl Esters of N-Benzoxycarbonyl Amino Acid

With the aid of a Pyrolysis-GC/TOF MS technique,the pyrolysis behaviour of two menthyl esters of N-benzoxycarbonyl amino acid was investigated.A clear pattern emerges involving the cleavage of the bond linking the menthyl ring to the carboxy group,followed by further degradation of the fragments.The major pyroproducts were p-menth-1-ene pyrolysed at a higher temperature or p-menth-2-ene pyrolysed at a lower temperature,and va-rious derivatives of cyclohexene pyrolyzed from the menthyl ring.In addition,some ...     

O-季铵化-N-壳聚糖Schiff碱的合成及表征

对壳聚糖氨基和羟基进行化学改性,合成了水溶性双功能化壳聚糖衍生物O-季铵化-N-壳聚糖Schiff碱(O-HTCCS);用红外光谱表征了产物的结构;确定了O-HTCCS的最佳合成条件,并测定了其溶解性能.结果表明,合成O-HTCCS的最佳条件为:壳聚糖Schiff碱/缩水甘油三甲基氯化铵(GTMAc)摩尔比为1∶5;反应时间24 h;反应温度70℃.在最佳条件下合成O-HTCCS的产率为78.5%,季铵化度为89.7%.与此同时,O-HTCCS的水溶性随季铵化度的增大而提高,季铵化度达到70%以上能溶于水;且其在有机溶剂中的溶解性优于壳聚糖.     

Effects of carbon nanotubes on dynamic mechanical property,thermal property,and crystal structure of poly(L‐lactic acid)

Effects of carbon nanotubes (CNT) on the dynamic mechanical property, thermal property, and crystal structure of poly(L ‐lactic acid) (PLLA) were investigated. Dynamic mechanical analysis (DMA) found that CNT via grafting modification with PLLA (CNT‐g‐PLLA) could result in effective reinforcing effects. Tan δ of DMA found that CNT‐g‐PLLA was compatible with the PLLA matrix, giving a single T_g of the composite with a higher CNT‐g‐PLLA loading giving a higher T_g of the composite. Wide angle X‐ray diffraction (WAXD) data demonstrated that CNT could assist the disorder‐to‐order (α′‐to‐α) transition in PLLA crystals but did not lead to a more compact chain packing of the crystal lattice in PLLA composites than in pure PLLA. The equilibrium melting temperature (T) obtained from Hoffman‐Weeks plots were found to increase with increasing CNT‐g‐PLLA content. Small angle X‐ray scattering data revealed that thicknesses of crystal layer and amorphous layer of PLLA both decreased with increasing CNT contents. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 145–152, 2010     

The crystal structures of chiral (<Emphasis Type="Italic">R</Emphasis>/<Emphasis Type="Italic">S</Emphasis>) (C<Subscript>8</Subscript>H<Subscript>11</Subscript>N)<Subscript>2</Subscript>·CuCl<Subscript>2</Subscript>

Two opposite configuration (R/S) of chiral complexes (C₈H₁₁N)₂·CuCl₂ were obtained from the reaction of chiral d(+)/l(−)-α-ethylphenyl amine with copper chloride (II) in dry ethanol. The crystal structures of 1a and 1b were characterized by IR, elemental analysis and X-ray crystallography.