Microenvironment-Sensitive Fluorescent Ligand Binds Ascaris Telomere Antiparallel G-Quadruplex DNA with Blue-Shift and Enhanced Emission

The development of small molecules that can selectively target G-quadruplex (G4) DNAs has drawn considerable attention due to their unique physiological and pathological functions. However, only a few molecules have been found to selectively bind a particular G4 DNA structure. We have developed a fluorescence ligand Q1 , a molecular scaffold with a carbazole–pyridine core bridged by a phenylboronic acid side chain, that acts as a selective ascaris telomere antiparallel G4 DNA ASC20 ligand with about 18 nm blue-shifted and enhanced fluorescence intensity. Photophysical properties revealed that Q1 was sensitive to the microenvironment and gave the best selectivity to ASC20 with an equilibrium binding constant K_a=6.04×10⁵ M⁻¹. Time-resolved fluorescence studies also demonstrated that Q1 showed a longer fluorescence lifetime in the presence of ASC20. The binding characteristics of Q1 with ASC20 were shown in detail in a fluorescent intercalator displacement (FID) assay, a 2-Ap titration experiment and by molecular docking. Ligand Q1 could adopt an appropriate pose at terminal G-quartets of ASC20 through multiple interactions including π–π stacking between aromatic rings; this led to strong fluorescence enhancement. In addition, a co-staining image showed that Q1 is mainly distributed in the cytoplasm. Accordingly, this work provides insights for the development of ligands that selectively targeting a specific G4 DNA structure.     

精细高分子化学选修课教学探索与实践

精细高分子化学是精细化工专业的一门重要选修课程,该课程的学习可以为学生从事精细高分子材料领域工作或相关科学研究打下基础。本文根据我校精细化工专业的学科特色及专业背景,明确学生对相关知识的需求情况,通过调整课程体系及教学内容,完善教学方式,优化评价机制,使精细高分子化学专业基础知识与相关科研进展及发展前沿融会贯通,丰富教学内容、激发学生兴趣,提高教学质量,满足不同学生学习目的与需求。     

电子束辐照灭菌对昭通酱品质影响研究

以昭通酱的感官评价、部分营养及理化成分为评价指标，研究电子束辐照剂量对其品质的影响。结果表明，当电子束辐照剂量为3.68 kGy时，昭通酱感官综合评价较好，真菌、大肠杆菌达到卫生标准，脂肪含量未显著下降（P＞0.05），过氧化值未显著上升（P＞0.05），6种大豆异黄酮含量未显著下降（P＞0.05），必需氨基酸（EAA）、总氨基酸（TAA）、呈味氨基酸（DAA），条件必需氨基酸（CEAA）未发生显著变化（P＞0.05），表明该剂量对昭通酱营养成分、理化指标的影响相对较小，且微生物指标达到卫生标准，是昭通酱电子束辐照灭菌的最佳剂量。     

Damage growth-based constitutive model of satin weave composites under different temperatures and strain rates

In this study, a constitutive model, which took into account the temperature and strain rate dependences of progressive damage behavior, was developed to describe the compressive behavior of satin weave carbon/epoxy composites over the temperature range of 298–448 K and strain rate range of 0.001–1100 s⁻¹. To further understand the mechanical behavior of satin weave carbon/epoxy composites, systematic experiments were first conducted using electronic universal testing machine and enhanced split Hopkinson pressure bar (SHPB) system. In addition, the progressive damage mechanism was observed with scanning electron microscope (SEM) and digital image correlation (DIC) technique. Results showed that the modulus and damage growth of composites are temperature and strain rate sensitive. Under quasi-static compression, failure mode changed from shear fracture to kink-band formation with increasing temperature. Samples failed predominantly by delamination under dynamic compression. It is shown that the mechanical behavior of satin weave composites obtained by the constitutive model agrees well with the experimental data over a wide range of temperature and strain rate. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47575.     

Bioreducible poly(amido amine) copolymers derived from histamine and agmatine for highly efficient gene delivery

Histamine (HIS) can facilitate the endosomal escape of polyplexes via the ‘proton sponge effect’ because of its imidazole groups. Agmatine (AGM) can improve the transmembrane process of polyplexes as a result of its guanidinium groups. Therefore, HIS and AGM were used as amino monomers to react with cystamine bisacrylamide (CBA) through Michael addition. The synthesized peptide‐mimicking poly(CBA‐HIS/AGM)s showed high transfection efficiency and low cytotoxicity, indicating their great potential as gene carriers. The results also demonstrated that the effects of HIS and AGM on the properties of poly(CBA‐HIS/AGM)s were different: HIS could increase their buffering capacities and bioreducibility, but AGM could facilitate their plasmid DNA packaging and condensing abilities. In addition, the results of transfection mechanism studies indicated that poly(CBA‐HIS/AGM) polyplexes entered into cells mainly via clathrin‐dependent endocytosis and they could efficiently escape the endosome, indicating endosomal escape was not the limiting step for gene delivery based on these polymers. © 2018 Society of Chemical Industry     

Hydrogen storage in sH binary hydrate: Insights from molecular dynamics simulation

sH hydrate is a kind of hydrate that is consisted of only organic large molecule and water. Since each organic large molecule can bring five small cages that easily capture hydrogen molecules, sH hydrate is potential hydrogen storage material. In this paper, methylcyclohexane-hydrogen hydrate was used for hydrogen storage. Two different processes, the simultaneous formation and the induced formation, were studied by molecular dynamics simulation. The simultaneous formations of methylcyclohexane-hydrogen binary hydrate were simulated at 230 K & 110 MPa and the hydrogen storage capacity of binary hydrate was 1.08 wt%. The induced formation of methylcyclohexane-hydrogen binary hydrate was simulated at 240–260 K &20–110 MPa.The simulation results showed that hydrogen storage capacity of hydrate was mainly affected by temperature. The hydrogen storage capacity of hydrates was low (≤1.0 wt%) at 250–260 K even the pressure increased to 110 MPa. While the hydrogen storage capacity was greatly improved (≥1.6 wt%) at 240 K. At 250–260 K, hydrogen molecules only entered the cavities that were near the interface, which seems that 5¹² cages layers obstructed the hydrogen molecules. The results indicated that the induced hydrogen formation required milder conditions than the simultaneously hydrogen storage formation, and the hydrogen storage was higher.     

片式微型变压器及相关材料研究

以化学法制备的高性能纳米NiCuZn铁氧体为原料,采用流延和丝网印刷工艺在930℃以下低温烧结,成功制备了外形尺寸仅为15mm×15mm×1mm和8mm×8mm×1mm两种适合表面贴装技术的片式微型变压器原型器件.通过改变其输入频率和电压,对变压比和相位移进行测量以及对波形的失真等的分析,得到该变压器在输入电压为2V～4V,频率为4MHz～6MHz的条件下具有比较稳定的变压效果.     

亚共晶Sn-Zn系合金无铅焊料的性能

通过差热分析(DTA),研究Sn-xZn合金(x=2.5~9)的非平衡熔化性能,发现在加热速度为5℃/min时,Sn-6.5Zn与Sn-9Zn的熔化特性相同;通过浸润法和铺展法表征Sn-xZn合金在Cu基材表面上的润湿性。结果表明:Sn-6.5Zn在Cu基材表面上的润湿性优于Sn-9Zn。研究速率为10-3s-1和10-1s-1时Sn-xZn的拉伸性能,结果发现:Sn-6.5Zn的抗拉强度与Sn-9Zn的相当,而延伸率高于Sn-9Zn。以搭接焊及界面剪切实验研究Sn-xZn/Cu焊点界面强度,发现焊点界面剪切强度随x的增加而提高,在x≥6.5时趋于稳定;x=6.5时剪切力最大,表明Sn-6.5Zn在Sn-Zn系中具有最好的钎焊工艺性能。