A fluorescence enhancement-based sensor for hydrogen sulfate ion

Sugar-aza-crown ether-based cavitand 1 can act as a selective turn-on fluorescence sensor for hydrogen sulfate ion in methanol among a series of tested anions. Spectroscopic studies, particularly NMR spectroscopy, revealed that the C-H hydrogen bonding between 1,2,3-triazole ring of cavitand 1 and hydrogen sulfate ion is crucial for the high selectivity of the receptor for hydrogen sulfate.     

KF polymerase-based fluorescence aptasensor for the label-free adenosine detection

We have developed a simple, inexpensive, and label-free method for the selective detection of adenosine. Klenow fragment polymerase (KF polymerase) is a commonly-used 5' to 3' DNA polymerase, it also has 3' to 5' exonuclease activity that can digest single-stranded DNA. An adenosine binding DNA aptamer was employed, the aptamer was split into two pieces of single-stranded DNA (aptamer-A1 + aptamer-A2). Without the addition of adenosine, aptamer-A1 and aptamer-A2 existed as single-stranded DNA which could be efficiently degraded by the exonuclease activity of KF polymerase. Much reduced background fluorescence was obtained when SYBR Green dye was added. However, in the presence of adenosine, aptamer-A1 and aptamer-A2 bound to adenosine, and hybridization of the complementary sequences resulted in the formation of a duplex DNA structure, which could initiate DNA polymerization. The addition of SYBR Green dye resulted in a very high fluorescence enhancement, which could be used for the quantification of adenosine.     

新型三嗪桥连的双1,8-萘酰亚胺衍生物的合成及其光物理行为

以1,8-萘酰亚胺和三聚氯氰为主要原料, 合成了两种由三嗪环桥连的双1,8-萘酰亚胺化合物3 和5. 采用紫外-可见光谱和荧光光谱等手段考察了两种化合物在不同溶剂中的光物理行为. 与参比化合物N-丁基-1,8-萘酰亚胺相比, 在二氯甲烷、三氯甲烷和甲醇等极性溶剂中, 化合物3和5除了在短波区(λ<400 nm)存在1,8-萘酰亚胺的特征荧光发射峰外, 在长波区(>450 nm)均产生一个较强的新荧光发射峰, 表现出分子内激基缔合物的光物理行为. 与化合物5相比, 由于化合物3特殊的构象异构, 其荧光强度发生严重的猝灭. 在非极性溶剂甲基环己烷中, 化合物5 由于存在较强的分子间氢键作用而聚集, 受激后形成了较稳定的分子间激基缔合物, 但未观察到明显的分子内激基缔合物的形成. 在甲苯溶剂中, 化合物3和5与甲苯分子形成了激基复合物, 并未形成分子内激基缔合物. 进一步研究3和5的固态激发态性质, 发现化合物3和5的固体薄膜受激后分别在465和469 nm处出现激基缔合物的特征荧光发射峰.     

Quantum-correlated photon pair generation in tellurite microstructured optical fibers

We theoretically investigated the generation of quantum-correlated photon pair through spontaneous four-wave mixing in tellurite microstructured optical fiber (MOF). We evaluated the performance of photon pair generation in tellurite fibers based on Raman gain coefficient spectra. It was shown that the TBSN16P6W tellurite fiber provided a low Raman noise on correlation photon generation over a wide pump-idler detuning range. We can choose proper tellurite composition to obtain a low Raman gain window over wide range for correlated photon pair generation. We also designed the tellurite MOF structure to obtain a small dispersion value with high nonlinear coefficient at telecommunication wavelengths, thus realize efficient quantum-correlated photon pair generation.     

Charge rate influence on the electrochemical performance of LiFePO<Subscript>4</Subscript> electrode with redox shuttle additive in electrolyte

Overcharge performance of LiFePO₄ cells is investigated through adding 2, 5-ditertbutyl 1, 4-dimethoxybenzene (DDB) as redox shuttle into electrolyte (RS electrolyte) at different charge rate. RS electrolytes with DDB works well as overcharge protection at low charge rate of less than 0.1 C. Novel charge/discharge characteristics are observed when charge rate increases in the cell with RS electrolyte. Especially, larger discharge capacities are obtained at the same discharge rate after charge rate gets higher than 0.1 C rate. Discharge capacity is larger in the cell with RS electrolyte than that in the cell without RS electrolyte at the same charge and discharge rate. At the same charge rate, cells with RS electrolyte have better cycling performances and larger discharge capacity than that with conventional electrolyte. These indicate that DDB accumulates in cathode with cycling and influences electrode–electrolyte interface reactions.     

平行因子分析法在太湖水体三维荧光峰比值分析中的应用

以太湖水样三维荧光光谱数据为例,提出在采用平行因子分析法(PARAFAC)处理后的荧光数据中提取荧光峰强度计算荧光峰比值进行水环境分析评价的方法,较直接在水样原始荧光谱图中获取的荧光峰强度更加准确客观。天然水体中各水样间由于受荧光团复杂多样性等因素的影响,某类荧光物质荧光峰的激发发射波长位置并不是固定不变的,就同一水样而言各类荧光峰之间的相互重叠干扰也将影响到荧光峰强度和位置的准确判断。而在PARAFAC模型各因子中提取相应荧光峰值可以保证各水样间同类荧光物质荧光峰在同一位置又有效减弱同一水样中各类荧光物质荧光峰之间的相互干扰,更加高效准确的利用荧光峰比值进行水环境分析。区域差异性分析时水样因子得分比值的区域变化与原始荧光峰比值变化趋势是一致的。     

An alternating variable method for the maximal correlation problem

The maximal correlation problem (MCP) aiming at optimizing correlations between sets of variables plays an important role in many areas of statistical applications. Up to date, algorithms for the general MCP stop at solutions of the multivariate eigenvalue problem (MEP), which serves only as a necessary condition for the global maxima of the MCP. For statistical applications, the global maximizer is quite desirable. In searching the global solution of the MCP, in this paper, we propose an alternating variable method (AVM), which contains a core engine in seeking a global maximizer. We prove that (i) the algorithm converges globally and monotonically to a solution of the MEP, (ii) any convergent point satisfies a global optimal condition of the MCP, and (iii) whenever the involved matrix A is nonnegative irreducible, it converges globally to the global maximizer. These properties imply that the AVM is an effective approach to obtain a global maximizer of the MCP. Numerical testings are carried out and suggest a superior performance to the others, especially in finding a global solution of the MCP.     

Molecularly imprinted aptamers of gold nanoparticles for the enzymatic inhibition and detection of thrombin

We prepared thrombin-binding aptamer-conjugated gold nanoparticles (TBA-Au NPs) through a molecularly imprinted (MP) approach, which provide highly efficient inhibition activity toward the polymerization of fibrinogen. Au NPs (diameter, 13 nm), 15-mer thrombin-binding aptamer (TBA(15)) with different thymidine linkers, and 29-mer thrombin-binding aptamer (TBA(29)) with different thymidine linkers (Tn) in the presence of thrombin (Thr) as a template were used to prepare MP-Thr-TBA(15)/TBA(29)-Tn-Au NPs. Thrombin molecules were then removed from Au NPs surfaces by treating with 100 mM Tris-NaOH (pH ca. 13.0) to form MP-TBA(15)/TBA(29)-Tn-Au NPs. The length of the thymidine linkers and TBA density on Au NPs surfaces have strong impact on the orientation, flexibility, and stability of MP-TBA(15)/TBA(29)-Tn-Au NPs, leading to their stronger binding strength with thrombin. MP-TBA(15)/TBA(29)-T(15)-Au NPs (ca. 42 TBA(15) and 42 TBA(29) molecules per Au NP; 15-mer thymidine on aptamer terminal) provided the highest binding affinity toward thrombin with a dissociation constant of 5.2 × 10(-11) M. As a result, they had 8 times higher anticoagulant (inhibitory) potency relative to TBA(15)/TBA(29)-T(15)-Au NPs (prepared in the absence of thrombin). We further conducted thrombin clotting time (TCT) measurements in plasma samples and found that MP-TBA(15)/TBA(29)-T(15)-Au NPs had greater anticoagulation activity relative to four commercial drugs (heparin, argatroban, hirudin, and warfarin). In addition, we demonstrated that thrombin induced the formation of aggregates from MP-TBA(15)-T(15)-Au NPs and MP-TBA(29)-T(15)-Au NPs, thereby allowing the colorimetric detection of thrombin at the nanomolar level in serum samples. Our result demonstrates that our simple molecularly imprinted approach can be applied for preparing various functional nanomaterials to control enzyme activity and targeting important proteins.     

等离子喷涂含钪氧化物阴极制备及发射特性研究

在三元碳酸盐中加入微量钪,利用大气等离子喷涂方法制备出含钪等离子喷涂氧化物阴极. 制备过程中,在三元碳酸盐原来配比基础上增加12%—22%(摩尔百分比)的碳酸钡进行混合, 并将该混合物进行造粒,在造粒过程中加入微量的钪.利用扫描电子显微镜分析了等离子喷涂材料的形态 和分布,表明符合等离子喷涂对粉末大小和形状的要求,并解决了等离子喷涂过程中钡的损失问题. 对这种新型氧化物阴极的分解排气过程进行详细分析,结果表明,排气时这种阴极比普通喷涂阴极出气少 且分解时间短.对发射性能及寿命进行测试,结果显示这种新型氧化物阴极的性能显著提高,阴极寿命延长.     

具有不同时延的多智能体系统一致性分析

针对有向加权且存在全局可达点的静态网络拓扑, 考虑了同时具有通信时延和输入时延的一阶、二阶智能体系统的运动一致性问题. 基于广义Nyquist准则与频域控制理论的方法, 分析并得到了网络中所有智能体渐进收敛到一致状态的充分条件. 通过该条件发现一致性的达到只与系统的耦合强度、智能体的输入时延以及各自的连接状态信息有关, 与通信时延无关. 但是, 通信时延的存在却要影响系统的动态特性. 仿真实验结果进一步验证了理论分析所得结论的正确性.