Synthesis and biological evaluation of a lipopeptide-based methamphetamine vaccine

We describe an application of carrier protein-free strategy in constructing a fully synthetic methamphetamine (METH) vaccine that contains three components: Toll-like receptor 2 ligand, Th2 epitope, and METH hapten. The immunological evaluation in mice revealed high titers of METH-specific antibodies induced by the construct and the activation of humoral immunity that would be beneficial for neutralization and clearance of the METH molecule. Behavioral experiments indicated that the synthetic vaccine attenuated the acquisition of METH-induced conditioned place preference and inhibited the initiation and expression of METH-induced locomotor sensitization. These results demonstrate that the lipopeptide-based vaccine has invoked an immune response and showed the potential of preventing the rewarding and psychoactive effects of METH.     

Asymmetric synthesis of dihydro-1,3-dioxepines by Rh(ii)/Sm(iii) relay catalytic three-component tandem [4 + 3]-cycloaddition

Heterocycles have been widely used in organic synthesis, agrochemical, pharmaceutical and materials science industries. Catalytic three-component ylide formation/cycloaddition enables the assembly of complex heterocycles from simple starting materials in a highly efficient manner. However, asymmetric versions remain a yet-unsolved task. Here, we present a new bimetallic catalytic system for tackling this challenge. A combined system of Rh(ii) salt and chiral N,N′-dioxide–Sm(iii) complex was established for promoting the unprecedented tandem carbonyl ylide formation/asymmetric [4 + 3]-cycloaddition of aldehydes and α-diazoacetates with β,γ-unsaturated α-ketoesters smoothly, affording various chiral 4,5-dihydro-1,3-dioxepines in up to 97% yield, with 99% ee. The utility of the current method was demonstrated by conversion of products to optically active multi-substituted tetrahydrofuran derivatives. A possible reaction mechanism was provided to elucidate the origin of chiral induction based on experimental studies and X-ray structures of catalysts and products.

Catalytic asymmetric tandem carbonyl ylide formation/[4 + 3]-cycloaddition of β,γ-unsaturated α-ketoesters, aldehydes and α-diazoacetates was achieved by using a bimetallic rhodium(ii)/chiral N,N′-dioxide–Sm(iii) complex catalyst.     

Quantitative interrogation of protein co-aggregation using multi-color fluorogenic protein aggregation sensors

Co-aggregation of multiple pathogenic proteins is common in neurodegenerative diseases but deconvolution of such biochemical process is challenging. Herein, we developed a dual-color fluorogenic thermal shift assay to simultaneously report on the aggregation of two different proteins and quantitatively study their thermodynamic stability during co-aggregation. Expansion of spectral coverage was first achieved by developing multi-color fluorogenic protein aggregation sensors. Orthogonal detection was enabled by conjugating sensors of minimal fluorescence crosstalk to two different proteins via sortase-tag technology. Using this assay, we quantified shifts in melting temperatures in a heterozygous model protein system, revealing that the thermodynamic stability of wild-type proteins was significantly compromised by the mutant ones but not vice versa. We also examined how small molecule ligands selectively and differentially interfere with such interplay. Finally, we demonstrated these sensors are suited to visualize how different proteins exert influence on each other upon their co-aggregation in live cells.

A little leak will sink a great ship! We prepared a series of multi-color protein aggregation sensors and developed a dual-color thermal shift assay to simultaneously and quantitatively report on protein co-aggregation of two different proteins.     

Characterization of Key Odorants in Scallion Pancake and Investigation on Their Changes during Storage

To characterize key odorants in scallion pancake (SP), volatiles were extracted by solvent extraction-solvent assisted flavor evaporation. A total of 51 odor-active compounds were identified by gas chromatography-olfactometry (GC-O) and chromatography–mass spectrometry (GC-MS). (Z/E)-3,6-Diethyl-1,2,4,5-tetrathiane was detected for the first time in scallion food. Application of aroma extract dilution analysis to extracts showed maltol, methyl propyl disulfide, dipropyl disulfide and 2-pentylfuran had the highest flavor dilution (FD) factor of 4096. Twenty-three odorants with FD factors ≥ 8 were quantitated, and their odor active values (OAVs) were calculated. Ten compounds with OAVs ≥ 1 were determined as the key odorants; a recombinate model prepared from the key odorants, including (E,E)-2,4-decadienal, dimethyl trisulfide, methyl propyl disulfide, hexanal, dipropyl trisulfide, maltol, acetoin, 2-methylnaphthalene, 2-pentylfuran and 2(5H)-furanone, successfully simulated the overall aroma profile of SP. The changes in odorants during storage were investigated further. With increasing concentrations and OAVs during storage, hexanal became an off-flavor compound.     

时间分辨激光光散射测量系统

自选设计，装配了一套时间分辨的激光光散射测量系统，该系统摄像机，录像机，计算机和自编的软件实现了一体化的数据采集，显示和分析过程，本文给出了该系统的应用实例，球晶的光散射和环氧树脂的固化反应诱导的相分离过程。     

新型多联吡啶的合成

设计并合成了一种新型配体１，２－二（６”－（６－甲基－４’－苯基－２，２’：６’，２”－三联吡啶基）乙烷，它是由１－（６’－甲基－２’－吡啶基）－３－苯基－２－丙烯－１－酮３与１－（６’－甲基－２’－吡啶基）－羰甲基吡啶碘盐４经改良的Ｋｒｏｈｎｋｅ法先制得取代三联吡啶５，然后在氩气流中，－８０℃与ＬＤＡ，氧化剂１，２－二溴乙烷反应，偶联生成新化合物６。３，４，５，６的结构经元素分析，ＩＲ，ＨＮＭＲ     

A new method for preparing TiO2 catalyst honeycombs without sintering

Composite catalyst honeycombs without sintering were prepared via kneading, mulling, extrusion molding, and solidifying at room temperature with the magnesite oxychloride gels modified by nano-rice husk ash (RHA) as a solidifying agent. The effects of nano-RHA and composite water-resistant agents on the water resistance of magnesite materials were studied. The solidification of the modified magnesite gels on TiO₂ catalyst honeycombs was analyzed. The experiments show that the proportional addition of nano-RHA markedly increases the water resistance of magnesite materials without reducing the bending strength, and the softening coefficient increases from 0.29 to 0.78. With further addiition of the complex water-resistant agents, the softening coefficient increases from 0.78 to 0.97. The optimal mass ratio of MgO in the solidifying agent to TiO₂ is 4:1, and the bending strength of unsintered catalyst honeycombs is 11.46 MPa. The desulfurization rate and denitration rate of this composite catalyst honeycomb on simulation smoke was 97 and 65 %, respectively, in 3 h.     

Al2O3-SiO2催化环己胺氧化制备环己酮肟

以Al2O3-SiO2为催化剂,用双氧水氧化环己胺制备了环己酮肟。考察了溶剂用量、催化剂用量、反应时间和反应温度等因素对催化性能的影响。结果表明,在溶剂乙腈与环己胺体积比为3∶1,催化剂质量分数31.0%,75℃反应5 h后的环己胺转化率为100%,环己酮肟选择性可达83.6%。并对环己胺催化氧化的反应机理作了初步的探讨。     

Cloning, Expression, and Characterization of β-mannanase from Bacillus subtilis MAFIC-S11 in Pichia pastoris

The β-mannanase gene (1,029 nucleotide) from Bacillus subtilis MAFIC-S11, encoding a polypeptide of 342 amino acids, was cloned and expressed in Pichia pastoris. To increase its expression, the β-mannanase gene was optimized for codon usage (mannS) and fused downstream to a sequence-encoding modified α-factor signal peptide. The expression level was improved by 2-fold. This recombinant enzyme (mannS) showed its highest activity of 24,600 U/mL after 144-h fermentation. The optimal temperature and pH of mannS were 50 °C and 6.0, respectively, and its specific activity was 3,706 U/mg. The kinetic parameters V _max and K _m were determined as 20,000 U/mg and 8 mg/mL, respectively, representing the highest ever expression level of β-mannanase reported in P. pastoris. In addition, the enzyme exhibited much higher binding activity to chitin, chitosan, Avicel, and mannan. The superior catalytic properties of mannS suggested great potential as an effective additive in animal feed industry.     

具有高散射能力的聚碳酸酯复合材料的制备与性能研究

以双酚A型聚碳酸酯(PC)为基体、苯乙烯-丙烯腈共聚物(SAN)为散射体,通过熔融共混方法制备了同时具备高透光率和高雾度的高散射聚碳酸酯光散射片,研究了SAN含量对光散射片微观结构和光散射性能的影响,发现透光率和雾度同时随着散射体含量增加而提高的现象.研究结果表明,当SAN含量低于30%时,分散相为球形颗粒,颗粒的平均粒径随着SAN含量的增加而增加,而颗粒的数量浓度则随之减小,这使得其透光率和雾度均随着SAN含量的增加而增加,当SAN含量为30%时,透光率和雾度达到最大值,分别为89.1%和91.7%.并结合Mie散射理论解释说明了透光率和雾度同时随着散射体含量的增加而提高的现象.但当SAN含量的进一步增加,分散相颗粒尺寸已远大于光波的波长,不再适用于Mie散射理论,且部分不再呈球形颗粒,使得PC片的透光率和雾度略有降低.