用转移电导计算BJT放大电路的电压放大倍数及对该问题的思考

BJT放大电路在静态电流较小时可以用转移电导计算其电压放大倍数。文中通过理论分析给出几种基本组态的BJT放大电路用转移电导计算电压放大倍数的公式,并通过实验实测出的电压放大倍数与理论计算出的电压放大倍数完全一致。因此可以引出在一定条件下把BJT也能看成是电压控制器件的结论。

伪广义哈密顿理论及其在多机电力系统非线性励磁控制中的应用

传统的电力系统广义哈密顿(Hamilton)实现方法难以考虑转移电导的影响,提出伪广义哈密顿系统理论,在广义哈密顿实现方法的基础上通过构造新的李亚普诺夫(Lyapunov)函数,实现了一类非线性系统的直接镇定控制。推导出可保证系统渐近稳定的条件和判据,将考虑转移电导情况下的多机电力系统模型表示成为伪广义耗散哈密顿形式,采用阻尼注入和能量补偿的思想进行励磁控制器的设计,物理意义更为明确,并结合电力系统的运行特点,给出判断系统渐近稳定性的近似方法。3机电力系统的仿真结果验证了所提出方法的正确性和控制策略的有效性。

基于伪广义Hamilton理论的电力系统时滞反馈励磁控制

广域测量信号的使用已使得电力系统成为时滞系统,反馈控制信号的时滞性对系统稳定性具有重要影响。为此,利用Pade近似方法,将反馈控制的时滞环节转换成微分方程,将显含的时滞环节隐含在系统的动态微分模型中,研究计及反馈时滞和转移电导的多机电力系统,将其表示成伪广义耗散Hamilton系统形式。利用伪广义耗散Hamilton系统理论和控制方法,结合电力系统的实际运行特点,得到计及广域反馈信号传输时滞的电力系统励磁控制律。IEEE 9节点系统的仿真结果表明,在计及时滞影响下所设计的发电机励磁控制器具有良好的控制效果。

Effect of linear carboxylic ester on low temperature performance of LiMn_2O_4-graphite cells

To improve the low-temperature performances of Li-ion cells, three types of linear carboxylic ester-based electrolyte, such as EC/EMC/EA（1：1：2, mass ratio）, EC/EMC/EP（1：1：2, mass ratio） and EC/EMC/EB（1：1：2, mass ratio）, were prepared to substitute for industrial electrolyte（EC/EMC/DMC）. Then, 18650-type Li Mn2O4-graphite cells（nominal capacity of 1150 mA ·h） were assembled and studied. Results show that the cells containing three types of electrolyte are able to undertake 5C discharging current with above 93% capacity retention at-20 °C. Electrochemical impedance spectra show that the discharge capacity fading of Li-ion cells at low temperature is mainly ascribed to the charge transfer resistance increasing with temperature decreasing. In comparison, the cells containing electrolyte of 1.0 mol/L LiPF6 in EC/EMC/EA（1：1：2, mass ratio） have the highest capacity retention of 90% at-40 °C and 44.41% at-60 °C, due to its lowest charge-transfer resistance.

Fluorescence Enhancement of Polyamine Derivatives of 1,8-Naphthalimide with Transition Metal Ions

A series of fluorescent chemosensors 1-3 were synthesized to detect transition metal ions. At the room temperature, fluorescence intensities of these chemosensors in acetonitrile without transition metal ions were found to be very weak, due to the process of the efficient intramolecular photoinduced electron transfer （PET）. However, after addition of the transition metal ions, the chemoscnsor 1-3 exhibits obvious fluorescence enhancement. Moreover, the intensity of the fluorescence emission of chemosensors increases significantly in the presence of Zn^2＋ and Cd^2＋. The fluorescent chemosensors with different polyamine as receptors show diverse affinity abilities to the transition metal ions and signal the receptor-metal ion interaction by the intensity change of fluorescence emission.

Photoinduced Electron Transfer in Dumbbell-type Fullerene Dyad

1,3-Dipolar cycloaddition of DTE-azomethine ylides （DTE： dithienyl-ethene） to C60 in refluxed toluene was used to synthesize novel dumbbell-type fullerene dimer 1. For the sake of comparison, the monoadduct 2 were also synthesized. The molecular geometries of these two compounds were determined by theoretical calculations with HF-3/21G method. UV-Vis and fluorescence experiments were carried out in solvents with different polarity at the room temperature. All the results indicated the existence of a photoinduced intramolecular electron transfer process between the donor and acceptor moieties.

Photoinduced Electron Transfer Between Mono-6-p-nitrobenzoyl-β- cyclodextrin and Adamantanamine-Cn-Co/Ni-porphyrins

Two series monot ailed porphyrins, Cobalt-5- {4- [ω- （1-adamant aneamino） alkyloxy] phenyl }- 10,15,20-triphenyl porphyrinate （CoPCnA, n=4,5,6） and Nickel-5-{4-[ω-（1-adamantaneamino）alkyloxy]phenyl}-10,15.20- triphenyl porphyrinate （NiPCnA, n=4,5,6）, were synthesized, in which the porphyrin moiety was connected to l-adamantanamine via a flexible hydrocarbon chain. The fluorescence quenching between these donor substrates and mono-6-p-nitrobenzoyl-β-cyclodextrin （NBCD） was studied in detail. Distinct fluorescence quenching occured in these supramolecular systems. This quenching was attributed to the photoinduced electron transfer （PET） inside the supramolecular assembly between the porphyrin donors and cyclodextrin acceptors. Detailed Stern-Volmer constants were measured and they were partitioned into dynamic Stern- Volmer quenching constants and static binding constants. It was demonstrated that the PET interaction between the porphyrin subunits and NBCD is indeed effective.

Synthesis of Porphyrin-Appended Pyridine as a Fluorescent Chemosensor for Cd（Ⅱ） and Hg（Ⅱ）

In this research, specific molecular sensors are classified according to the type of receptor-cation interaction, that is ligand-metal interactions. Receptors are based on a multidentate protoporphyrin-appended pyridine platform, which leaves at least a vacant coordination site for the incoming metal ions. A protoporphyrin-appended pyridine, 2,5-pyridine dicarboxyamidyl-8,13-bis（vinyl）-3,7,18,17-tetramethyl-21 H, 23 H-porphyrin（P-PTP）, was designed and synthesized. Its application as potential fluoroionophore for recognition of cadmium and mercury ions is reported. P-PTP shows chelation-enhanced fluorescence effect with Cd（Ⅱ） and Hg（Ⅱ） via the interruption of photoinduced electron transfer （PET） process, which has been utilized as the basis of the fabrication of the metal ions-sensitive fluorescent chemosensor. The analytical performance characteristics of the proposed Cd（Ⅱ）- and Hg（Ⅱ）- sensitive chemosensors were investigated. It shows a linear response toward Cd（Ⅱ） and Hg（Ⅱ） in the concentration range of 1.0×10-3 to 1.0×10-7 M with a limit of detection of 1.0×10-7 M and 0.5×10-7M for Cd（Ⅱ） and Hg（Ⅱ）, respectively. The chemosensor shows good selectivity for Cd（Ⅱ） over a large number of other transition metal ions, i.e., Cu（Ⅱ）, Zn（Ⅱ） and mixed metal ions.

Construction of Type I Aggregation-Induced Emission Photosensitizers for Photodynamic Therapy via Photoinduced Electron Transfer Mechanism

Photodynamic therapy(PDT)as a non-invasive anticancer modality has received increasing attention due to its advantages of noninvasiveness,high temporospatial selectivity,simple and controllable operation,etc.PDT mainly relies on the generation of toxic reactive oxygen species(ROS)by photosensitizers(PSs)under the light irradiation to cause cancer cell apoptosis and death.However,solid tumors usually exhibit an inherent hypoxic microenvironment,which greatly limits the PDT efficacy of these high oxygen-dependent conventional type II PSs.Therefore,it is of great importance to design and develop efficient type I PSs that are less oxygen-dependent for the treatment of hypoxic tumors.Herein,a new strategy for the preparation of efficient type I PSs by introducing the photoinduced electron transfer(PET)mechanism is reported.DR-NO_(2) is obtained by introducing 4-nitrobenzyl to(Z)-2-(5-(4-(diethylamino)-2-hydroxybenzylidene)-4-oxo-3-phenylthiazolidin-2-ylidene)malononitrile(DR-OH)with aggregation-induced emission(AIE)feature.The AIE feature ensures their high ROS generation efficiency in aggregate,and the PET process leads to fluorescence quenching of DR-NO_(2) to promote triplet state formation,which also promotes intramolecular charge separation and electron transfer that is conducive for type I ROS particularly superoxide radicals generation.In addition,DR-NO_(2) nanoparticles are prepared by nanoprecipitation to possess nanoscaled sizes,high cancer cell uptake,and excellent type I ROS generation ability,which results in an excellent performance in PDT ablation of MCF-7 cancer cells.This PET strategy for the development of type I PSs possesses great potential for PDT applications against hypoxic tumors.

Molecular-based conducting magnet

Molecular-based conducting magnet or magnetic conductor, is an overlap of organic conductor and molecular magnet. Due to the existence of ferromagnetism, antiferromagnetism and quantum magnetism in insulated charge-transfer salt, it becomes a common sense that magnetism is not good for conductivity. After the discovery of first molecular-based metallic ferromagnet, molecular-based conducting magnet with n-unit from organic conductor and magnetism from coordination counterion became a hot area. The metallic ferromagnet, semiconductor room-temperature ferrimagnet, metallic weak ferromagnet and supercon- ducting antiferromagnet have been discovered. The new molecular-based conducting magnet with higher conductivity and higher magnetic ordering temperature is expected.

Selective DNA detection at Zeptomole level based on coulometric measurement of gold nanoparticle-mediated electron transfer across a self-assembled monolayer

A selective DNA sensing with zeptomole detection level is developed based on coulometric measurement of gold nanoparticle （AuNPs）-mediated electron transfer （ET） across a self-assembled monolayer on the gold electrode. After immobilization of a thiolated hairpin-structured DNA probe, an alkanethiol monolayer was self-assembled on the resultant electrode to block [Fe（CN）6]3-/4 in a solution from accessing the electrode. In the presence of DNA target, hybridization between the DNA probe and the DNA target breaks the stem duplex of DNA probe. Consequently, stem moiety at the 3＇-end of the DNA probes was removed from the electrode surface and made available for hybridization with the reporter DNA-AuNPs conjugates （reporter DNA-AuNPs）. The thiolated reporter DNA matches the stem moiety at the 3＇-end of the DNA probe. AuNPs were then en- larged by immersing the electrode in a growth solution containing HAuCI4 and H202 after the reporter DNA-AuNPs bound onto the electrode surface. The enlarged AuNPs on the electrode restored the ET between the electrode and the [Fe（CN）6]3 -/4-, as a result, amplified signals were achieved for DNA target detection using the coulometric measurement of Fe（CN）63- elec- tro-reduction by prolonging the electrolysis time. The quantities of ET on the DNA sensor increased with the increase in DNA target concentration through a linear range of 3.0 fM to 1.0 pM when electrolysis time was set to 300 s, and the detection limit was 1.0 fM. Correspondingly, thousands of DNA （zeptomole） copies were detected in 10-μL samples. Furthermore, the DNA sensor showed excellent differentiation ability for single-base mismatch.

Large work function shift of organic semiconductors inducing enhanced interracial electron transfer in organic optoelectronics enabled by porphyrin aggregated nanostructures

We report on large work function shifts induced by the coverage of several organic semiconducting （OSC） films commonly used in organic light emitting diodes （OLEDs） and organic photovoltaics （OPVs） with a porphyrin aggregated layer. The insertion between the organic film and the aluminum cathode of an aggregated layer based on the meso-tetrakis（1-methylpyridinium-4-yl） porphyrin chloride （porphyrin 1）, with its molecules adopting a face-to-face orientation parallel to the organic substrate, results in a significant shift of the OSC work function towards lower values due to the formation of a large interfacial dipole and induces large enhancement of either the OLED or OPV device efficiency. OLEDs based on poly[（9,9-dioctylfluorenyl-2,7-diyl）-co-（1,4-benzo-2,1＇,3-thiadiazole）J （F8BT） and incorporating the porphyrin 1 at the cathode interface exhibited current efficiency values up to 13.8 cd/A, an almost three-fold improvement over the efficiency of 4.5 cd/A of the reference device. Accordingly, OPVs based on poly（3- hexylthiophene） （P3HT）, [6,6]-phenyl-C61 butyric acid methyl ester （PC61BM） and porphyrin 1 increased their external quantum efficiencies to 4.4% relative to 2.7% for the reference device without the porphyrin layer. The incorporation of a layer based on the zinc meso-tetrakis （1-methylpyridinium-4-yl）porphyrin chloride （porphyrin 2）, with its molecules adopting an edge-to-edge orientation, also introduced improvements, albeit more modest in all cases, highlighting the impact of molecular orientation.

A chain-type diamine strategy towards strongly anisotropic triiodide of DMEDA·I6

Linearly bonded triiodide chains with fairly small distance between the adjacent iodine ions feature a facile electron transfer and highly anisotropic properties.Here,we demonstrate a novel strategy towards a new one-dimensional linear triiodide DMEDA·I6,using chain-type N,N'-dimethylethanediamine(DMEDA)cation to coordinate triiodine ions.This triiodide has the shortest distance between adjacent I3^- and good linearity.An estimated electronic band gap of1.36 e V indicates its semiconducting properties.100 fold differences both in polarization-sensitive absorption and effective mass were achieved by simulation,with directions parallel and perpendicular to the a-axis of DMEDA·I6.The DMEDA·I6 single crystal-based photodetectors show a good switching characteristic and a distinct polarization-sensitive photoresponse with linear dichroic photodetection ratio of about 1.9.Strongly anisotropic features and semiconducting properties of DMEDA·I6 make this triiodide system an interesting candidate for polarization related applications.

Theoretical investigation of the non-Condon effect on electron transfer:Application to organic semiconductor

The non-Condon effect plays an important role in the process of electron transfer (ET). Several theoretical models have been proposed to investigate its effect on ET rates. In this paper,we overview a theoretical method for the calculations of the non-Condon ET rate constants proposed by us,and its applications to organic semiconductors. First,full quantum expressions of the non-Condon ET rates are presented with the electronic couplings having exponential,Gaussian and linear dependences in terms of the nuclear coordinates,respectively. The proposed formulas have closed forms in time domain and they thus can be easily applied in multi-mode systems. Then,the driving force dependences of the ET rates involving the non-Condon effect are calculated with the use of full quantum mechanical formulas. It is found that these dependences show very different prop-erties from the Marcus one. As an example of applications,the approaches are used to investigate the non-Condon effect on the mobility of the organic semiconductor dithiophene-tetrathiafulvalene (DT-TTF). The results manifest that the non-Condon ef-fect enhances ET rates compared with the Condon approximation,and static fluctuations of electronic coupling dominate the ET rate in the DT-TTF,which has been confirmed by the molecular dynamics simulation.