A new mapping rule for RNA secondary structures with its applications

According to the characterization of RNA secondary structures, the RNA secondary structures are transformed into elementary sequences, namely characteristic sequences of RNA secondary structures, by representing A, U, G, C in A-U/ G-C pairs, as A′, U′, G′, C′. Based on the representation, three recurrences for mapping RNA secondary structures into 1-D graph, 2-D graph and 3-D graph are given, respectively. Furthermore, a frequency-based method for RNA secondary structures is given in terms of 1-D graph.     

Fabrication and characteristics of organic semiconductor nanoparticles of copper phthalocyanine oligomers

Nanoparticles of copper phthalocyanine oligomers (O-CuPc) with peripheral carboxylic acid groups have successfully been prepared by a simple method of liquid phase direct precipitation in the presence of different surfactants. X-ray diffraction patterns, transmission electron microscopy, and UV-visible spectra are employed to characterize the novel organic nanoparticles. The sizes and size distribution of the resulting O-CuPc nanoparticles show a noticeable dependence on surfactants. Nonionic surfactant is helpful in forming uniform nanoparticles. Also we observe a remarkable nanosize effect of the O-CuPc particles.     

A sensitive DNA biosensor based on the distance dependent quenching of Silica@Ru(bpy)32+-chitosan-GO electrochemiluminescence by Ferrocene@Gold nanoparticles

A sensitive electrochemiluminescence (ECL) biosensor for the specific DNA sequence of hepatitis C virus (HCV) was developed based on the efficient quenching effect of the ferrocene cluster functionalized gold nanoparticles (Fc@AuNPs) on the ECL of electrodeposited silica@Ru(bpy)₃²⁺-chitosan-graphene oxide nanocomposite (SiO₂@Ru−CS−GO). Graphene oxide (GO) can accelerate electron transfer rate, thus improving the ECL of Ru(bpy)₃²⁺ on electrode surface. The molecular beacons (MB) was fixed to SiO₂@Ru−CS−GO by glutaraldehyde (GA) using the Schiff reaction between amino groups of chitosan (CS) and MB. The ECL of SiO₂@Ru−CS−GO was depressed greatly by the Fc@AuNPs labelled at the end of MB, then, a stronger ECL was observed when the distance between Fc@AuNPs and SiO₂@Ru−CS−GO increased after the hybridization of target DNA with MB. Under optimum conditions, the restored ECL intensity increased linearly with the target DNA concentration in the range of 1.0×10⁻¹⁶∼1.0×10⁻¹⁰ mol ⋅ L⁻¹, and the limit of detection (LOD) is 1.4×10⁻¹⁷ mol ⋅ L⁻¹. The proposed method exhibits acceptable stability and reproducibility. In general, the constructed HCV biosensor can be used for the sensitive detection of HCV in human serum, suggesting potential application prospects in bioanalysis.     

Solid Interhalogen Compounds with Effective Br0 Fixing for Stable High-energy Zinc Batteries

Though massive efforts have been devoted to exploring Br-based batteries, the highly soluble Br₂/Br₃⁻ species causing rigorous “shuttle effect”, leads to severe self-discharge and low Coulombic efficiency. Conventionally, quaternary ammonium salts such as methyl ethyl morpholinium bromide (MEMBr) and tetrapropylammonium bromide (TPABr) are used to fix Br₂ and Br₃⁻, but they occupy the mass and volume of battery without capacity contribution. Here, we report an all-active solid interhalogen compound, IBr, as a cathode to address the above challenges, in which the oxidized Br⁰ is fixed by iodine (I), thoroughly eliminating cross-diffusing Br₂/Br₃⁻ species during the whole charging and discharging process. The Zn||IBr battery delivers remarkably high energy density of 385.8 Wh kg⁻¹, which is higher than those of I₂, MEMBr₃, and TPABr₃ cathodes. Our work provides new approaches to achieve active solid interhalogen chemistry for high-energy electrochemical energy storage devices.     

Low Bandgap 2D Perovskite Single Crystal with Anomalous-large Charges/ions Collection Ratio for Ultra-sensitive and Stable X-ray Detectors

The low-dimensional halide perovskites have attracted increasing attention due to their improved moisture stability, reduced defects, and suppressed ions migration in many optoelectronic devices such as solar cells, light-emitting diodes, X-ray detectors, and so on. However, they are still limited by their large band gap and short charge carriers’ diffusion length. Here, we demonstrate that the introduction of metal ions into organic interlayers of two-dimensional (2D) perovskite by cross-linking the copper paddle-wheel cluster-based lead bromide ([Cu(O₂C−(CH₂)₃−NH₃)₂]PbBr₄) perovskite single crystals with coordination bonds can not only significantly reduce the perovskite band gap to 0.96 eV to boost the X-ray induced charge carriers, but can also selectively improve the charge carriers’ transport along the out-of-plane direction and blocking the ions motion paths. The [Cu(O₂C−(CH₂)₃−NH₃)₂]PbBr₄ single-crystal device can reach a record charges/ions collection ratio of 1.69×10¹⁸±4.7 % μGy_air⁻¹ s, and exhibit a large sensitivity of 1.14×10⁵±7% μC Gy_air⁻¹ cm⁻² with the lowest detectable dose rate of 56 nGy_air s⁻¹ under 120 keV X-rays irradiation. In addition, [Cu(O₂C−(CH₂)₃−NH₃)₂]PbBr₄ single-crystal detector exposed to the air without any encapsulation shows excellent X-ray imaging capability with long-term operational stability without any attenuation of 120 days.     

Hydrogen peroxide biosensor based on electrodeposition of zinc oxide nanoflowers onto carbon nanotubes film electrode

A new amperometric biosensor for hydrogen peroxide was developed based on adsorption of horseradish peroxidase at the glassy carbon electrode modified with zinc oxide nanoflowers produced by electrodeposition onto multi-walled carbon nanotubes （MWNTs） film. The morphology of the MWNTs/nano-ZnO electrode has been investigated by scanning electron microscopy （SEM）, and the electrochemical performance of the electrode has also been studied by amperometric method. The resulting electrode offered an excellent detection for hydrogen peroxide at -0.11 V with a linear response range of 9.9×10^-7 to 2.9×10^-3 mol/L with a correlation coefficient of 0.991, and response time 〈5 s. The biosensor displays rapid response and expanded linear response range, and excellent stability.     

A pure blue light emitting binaphthyl derivative：Synthesis and properties

A binaphthyl derivative with pyrene on 3 and 3＇ positions was synthesized and characterized via Suzuki coupling reaction. Emission maximum in solution was located at 390 nm with a quantum efficiency of 68% by taking 9,10-diphenyl anthracene as reference,while it is shifted to 450 nm with FWHM of 104 nm resulting from aggregation state in solid film.Glass transition temperature（Tg）and decomposition temperature were measured to be 184 and 447℃,respectively,by DSC and TGA.Unlike its photoluminescence spectrum,electroluminescent spectrum peaked at about 460 nm and shows a FWHM of 69 nm corresponding to a pure blue emission.The turn-on voltage,luminance and efficiency maximum were 5 V,2953 cd/m^2 and 1.37cd/A with CIE color coordinate of（0.16,0.15）,in the device structure of ITO/NPB（40nm）/PY-BN-PY（15nm）/BPhen（40nm）/Mg：Ag.     

A new method for quantitatively characterizing atmospheric oxidation capacity

Based on atmospheric chemical kinetics, the rate constant of overall pseudo-first order oxidation re-moval of gaseous pollutants (Kpor,T) is proposed to characterize the atmospheric oxidation capacity in troposphere. Being a quantitative parameter, Kpor,T can be used to address the issues related to at-mospheric oxidation capacity. By applying this method, the regional oxidation capacity of the atmos-phere in Pearl River Delta (PRD) is numerically simulated based on CBM-IV chemical mechanism. Re-sults show the significant spatio-temporal variation of the atmospheric oxidation capacity in PRD. It is found that OH initiated oxidations, heterogeneous oxidation of SO2, and photolysis of aldehydes are the three most important oxidation processes influencing the atmospheric oxidation capacity in PRD.     

Theoretical studies on Ru(fppz)2(CO)L (L = N -heterocyclic ligand): Electronic structure, absorption, phosphorescence, and solvatochromism

A series of ruthenium(II) complexes Ru(fppz)₂(CO)L [fppz = 3-trifluoromethyl-5(2-pyridyl)pyrazole; L = pyridine (1), 4-dimethylaminopyridine (2), 4-cyanopyridine (3)] were designed and investigated theoretically to explore their electronic structures, absorption, and emissions as well as the solvatochromism. The singlet ground state and triplet excited state geometries were fully optimized at the B3LYP/LANL2DZ and CIS/LANL2DZ level, respectively. The HOMO of 1–3 is composed of d_yz(Ru) atom and π(fppz). The LUMO of 1 and 2 is dominantly contributed by π*(fppz) orbital, but that of 3 is contribute by π*(L). Absorption and phosphorescence in vacuo, C₆H₁₂, and CH₃CN media were calculated using the TD-DFT level of theory with the PCM model based on the optimized ground and excited state geometries, respectively. The lowest-lying absorption of 1 and 2 at 387 and 391 nm is attributed to {[d_yz(Ru) + π(fppz)] → [π*(fppz)]} transition, but that of 3 at 479 nm is assigned to {[d_yz(Ru) + π(fppz)] → [π*(L)]} transition. The phosphorescence of 1 and 2 at 436 and 438 nm originates from ³{[d_yz(Ru) + π(fppz)] [π*(fppz)]} excited state, while that of 3 at 606 nm is from ³{[d_yz(Ru) + π(fppz)] [π*(L)]} excited state. The calculation results showed that the absorption and emission transition character can be changed from MLCT/ILCT to MLCT/LLCT transition by altering the substituent on the L ligand. The phosphorescence of 1 and 2 does not have solvatochromism, but that of 3 at 606 nm (vacuo), 584 nm (C₆H₁₂), and 541 nm (CH₃CN) is strongly dependent on the solvent polarity, so introducing electron-withdrawing group on ligand L will induce remarkable solvatochromism. Supported by the National Natural Science Foundation of China (Grant Nos. 20573042, 20703015, and 20333050)     

Precipitation polymerization in acetic acid: synthesis of monodisperse cross-linked poly(divinylbenzene) microspheres

This paper reports two important results with cross-linked precipitation polymerization. (1) Acetonitrile, a substance harmful to human health, is the most commonly used solvent for the synthesis of cross-linked polymeric microspheres by precipitation polymerization. Here, the much safer acetic acid replaced acetonitrile as a solvent in the precipitation polymerization of monodisperse cross-linked poly(divinylbenzene) (PDVB-55) microspheres. Pumpkin-like particles and microspheres were obtained. XPS results displayed a significant amount of double bonds on the surface of the particles. The effect of monomer content, temperature, and initiator amount on the formed particles were studied. For a DVB loading below 1 vol % at 70 degrees C, monodisperse microspheres with smooth surfaces and narrow diameters were successfully obtained. With a DVB loading of 2 vol % and by observing the shapes of particles obtained with three different temperature(60, 70, and 80 degrees C), we found that more spherical particles were obtained at higher temperatures and pumpkin-like particles were obtained at lower temperatures. No significant differences in morphology or the coefficient of variation (CV) of the particles were obtained for different initiator loadings, whereas the particle diameters could be increased with increased initiator concentrations. (2) In order to obtain a better understanding of the formation mechanism of these particles, time-dependent experiments, for the first time, were conducted in a hydrophobic monomer system. By tracing the whole polymerization process, some important results were found. First, with the polymerization time at 70 degrees C, the particle diameters were found to increase from 800 nm to 3.0 microm, the CV displayed a decrease, and the amount of spheres and the spherical evenness of the particle surfaces improved. Second, by quantitatively calculating the particle number from the yields and diameters data, it is found that starting from 3.1% yield or two hours reaction time the total amount of particles in the system is almost a constant (about 9.6 x 10 (8)/L), which means that no homocoagulation occurred and no new particles were generated after nucleation, and there is a linear relation between cubic diameters and yields. These two results give us a distinct impression that particle growth almost comes from capturing of newly formed oligomers. Based on the above results, a scheme for the particle formation is proposed, which shows that that pumpkin-like particles are caused by a prolonged nucleation including the homocoagulation of primary nuclei. The growth of the particles includes two modes, an in situ surface polymerization of monomer and the adsorption of PDVB-55 oligomers. The differences between results in acetonitrile and in acetic acid (higher yields, smaller size, not spherical but pumpkin-like particles in acetic acid) were due to the lower solubilizability of acetic acid which is the so-called proton-containing solvent with the hydrogen bonding structure.