Large gate modulation in the current of a room temperature single molecule transistor

We have demonstrated a single molecule field effect transistor (FET) which consists of a redox molecule (perylene tetracarboxylic diimide) covalently bonded to a source and drain electrode and an electrochemical gate. By adjusting the gate voltage, the energy levels of empty molecular states are shifted to the Fermi level of the source and drain electrodes. This results in a nearly 3 orders of magnitude increase in the source-drain current, in the fashion of an n-type FET. The large current increase is attributed to an electron transport mediated by the lowest empty molecular energy level when it lines up with the Fermi level.     

杂化硅胶整体材料研磨法制备混合型高效液相色谱固定相

以聚乙二醇（PEG）为致孔剂，四甲氧基硅烷（TMOS）和乙烯基三甲氧基硅烷（VTMS）为杂化硅胶前驱体，在乙酸催化作用下使硅烷发生水解，在尿素加热分解提供的碱性环境下水解的硅烷进一步缩聚得到杂化硅胶整体材料。将此整体材料用球磨机研磨，然后用三羟甲基氨基甲烷处理，并洗涤干燥得到粒径为3 μm左右的硅胶颗粒。探索了不同反应条件对硅胶颗粒的大小、比表面积和孔径、表面形貌和分散性的影响；当TMOS和VTMS体积比为3：1时可以得到孔径为7.5 nm和比表面积为245 m²/g的硅胶颗粒。通过对所制得的硅胶颗粒表面进行C18（十八烷基二甲基氯硅烷）键合修饰和巯基-烯点击反应，得到混合型高效液相色谱固定相。对此固定相的测试结果表明以上硅胶色谱填料的制备方法具有一定的实用性。     

Fabrication of hyaluronic acid-based nanoparticles and studies on their radical scavenging activity

The purpose of this paper is to study the stability, radical scavenging activities, and bio-safety of cysteine-conjugated hyaluronic acid nanoparticles (Cys-conj-HA NPs). Additionally, the feasibility of utilizing these NPs as drug delivery systems is discussed. The structures of synthesized Cys-conj-HA polymers were analyzed using ¹H nuclear magnetic spectrum (¹H NMR) and Fourier transform infrared spectroscopy (FTIR) spectra. The stability, radical scavenging activity, and bio-safety of fabricated Cys-conj-HA NPs were investigated. Transmission electron microscopy (TEM) photograph illustrated that Cys-conj-HA NPs possessed spherical shapes with an average diameter of approximately 230 nm. Furthermore, these NPs exhibited high stability at temperatures of 4, 25, and 37°C. Notably, Cys-conj-HA NPs demonstrated significant free radical scavenging capabilities. The high cell viability observed indicated the absence of cytotoxicity from Cys-conj-HA NPs. Additionally, bio-safety studies revealed that these NPs did not induce acute toxicity in the blood and viscera of cargo-free NPs treated mice. Elisa assays indicated that there was no significant difference in the concentrations of interferon-γ (INF-γ) and tumor necrosis factor-α (TNF-α) between Cys-conj-HA NPs and normal saline (NS) treated mice (ns, p > 0.05), suggesting the absence of an inflammatory reaction caused by these NPs. Consequently, it can be concluded that Cys-conj-HA NPs are sufficiently safe to be employed as a vehicle for delivering oxidizing drugs.     

基于多巴胺-量子点的比色免疫分析法对甲胎蛋白的高灵敏检测

基于抗原抗体识别特异性,以多巴胺-Mn/ZnS量子点(DA-QDs)为反应媒介,紫外可见分光光度计为检测手段,采用柠檬酸钠还原法制备金纳米颗粒(AuNPs),其表面用辣根过氧化物酶(HRP)和羊抗小鼠免疫球蛋白G (IgG)修饰获得功能化二抗(IgG-AuNPs-HRP)作为信号放大标签,构建一种简便高灵敏的检测方法....     

基于SiPM读出的塑料闪烁体探测器时间性能研究

研究了基于硅光电倍增管(SiPM)双端读出的面积为10 cm ×10 cm的薄塑料闪烁体探测器的时间性能。239Pu放射源测试结果显示:(1)在多支SiPM串连读出方式下,随着SiPM数量的增加,探测器时间分辨逐渐变好;(2)在固定12支SiPM数量不变的情况下,并联支路越多,探测器时间分辨越差;(3)采用快时间塑料闪烁体并增加其厚度,可有效提高探测器时间分辨;(4)采用比束斑尺寸更大的塑料闪烁体,可有效提高探测器时间分辨的位置均匀性;(5)对于1 mm厚的EJ232塑料闪烁体探测器,在单端12支SiPM串行连接的情况下,可获得好于131 ps的时间分辨。这一研究对RIBLL2起始时间探测器的升级改造具有重要的指导意义。     

用于条纹相机的计算机图象读出系统

针对条纹相机的使用要求研制了一套计算机图象读出系统,其特点是采用了积分时间可变的单次外同步CCD,保证了对瞬时结果的准确读出,从而可进行绝对测量;软件上采用WINDOWS编程,界面规范清晰易操作,数据处理充分考虑了条纹相机的使用特点,开放性的数据结构使得处理功能的扩展十分容易。     

Molecular Imprint for Electrochemical Detection of Streptomycin Residues Using Enzyme Signal Amplification

We have designed a new molecularly imprinted co‐polymer (MIP) for the sensitive detection of streptomycin (STR) in food using enzymes as signal amplification. The MIP was fabricated via co‐polymerization of aniline and o‐phenylenediamine on gold substrate in the presence of STR as template. The assay is based on competitive binding of free STR and glucose oxidase‐labeled STR (GOx‐STR) to the imprinters on the MIP. On addition of glucose, hydrogen peroxide is formed that is detected by differential pulse voltammetry. Under optimal conditions, the decrease of the catalytic current is proportional to the STR concentration in the range from 0.01 to 10 ng mL^?1, with a detection limit (LOD) of 7.0 pg mL^?1 STR (at 3s_B). Intra‐ and inter‐assay coefficients of variation (CVs) are<10.5 %. The system was further validated and evaluated with STR‐spiked samples including honey and milk, and the recovery was between 82 and 124.2 %.     

Target‐stimulated DNAzyme Concatamers Released from Aptasensor for Highly Sensitive and Specific Detection of Progesterone

Aiming at the detection of ultralow concentration target progesterone (Pro), a novel electrochemical aptasensor based on DNAzyme concatamers signal amplification strategy was proposed. The strategy consists of target DNA strands (TDNAs), and two different hairpin DNA molecules (H1 and H2). The signal is amplified by the large amount of DNAzyme. The TDNAs modified on the electrode open H1 structures in sequence and propagate a reaction of hybridization events between two alternating hairpins (H1and H2) to obtain abundant DNAzyme concatamers. Upon target Pro introduction, a specific Pro‐TDNAs reaction was executed, thereby resulting in the release of DNAzyme concatamers from the electrode. Subsequent differential pulse voltammetry(DPV) detection of aminoazobenzene (DAP) resulting by DNAzyme catalyze the oxidation of o‐phenylenediamine (OPD) with the aid of hydrogen peroxide (H₂O₂). Likewise, a small amount of target Pro can efficiently induce the release of a large number of the DNAzyme from the electrode in the form of DNAzyme concatamer. Under optimal conditions, the the proposed assay presents good electrochemical responses for determination of target Pro in the range of 0.5 to 15 ng/mL with the detection limit of 0.36 ng/mL. In addition, the resulting sensor can successfully distinguish Pro from coexisting interfering substance and show good stability and high repeatability. What's more, the methodology has also been demonstrated by assaying Pro‐spiked samples in serum.     

低共熔溶剂预处理木质纤维素生产生物丁醇

生物丁醇被认为是一种能够直接代替汽油的生物燃料,可满足经济发展对可持续液体燃料的需求。木质纤维素可再生,来源广泛且廉价,是生产生物丁醇的理想原料。但木质纤维素结构复杂,难以直接水解利用,高效的预处理方式是其商业化应用的关键。低共熔溶剂(DES)是一种环境友好的新型溶剂,具有成本低、绿色低毒、溶解能力强、良好的选择性和生物相容性等优点,有着较高的生物质预处理潜力。本文首先介绍了DES的种类和性质;其次,综述了木质纤维素中各组分在DES中的溶解效率,讨论了DES预处理木质纤维素对酶水解和丁醇发酵过程的影响;再次,通过对各种生物加工过程的梳理,对整合生物过程在生产生物丁醇领域的应用潜力进行了评述;最后,对DES预处理木质纤维素生产生物丁醇领域今后的工作做出了展望。