Photovoltaic Processes of Singlet and Triplet Excited States in Organic Solar Cells

This article reports the respective photovoltaic processes of singlet and triplet photoexcited states in dissociation and charge reactions based on the studies of magnetic‐field effects of photocurrents. The magnetic‐field effects of photocurrents reveal that weak donor‐acceptor interactions lead to a two‐step photovoltaic process: dissociation in polaron‐pair states evolved from singlet excitonic states and exciton‐charge reactions occurred in triplet excitonic states in the generation of the photocurrent. However, strong donor‐acceptor interactions yield a one‐step photovoltaic process: direct dissociation of both singlet and triplet excitons in bulk‐heterojunction organic solar cells. In addition, the magnetic‐field effects of photocurrents indicate that the dissociated electrons and holes form charge‐transfer complexes with singlet and triplet spin configurations at donor‐acceptor intermolecular interfaces. As a result, the magnetic‐field effects of photocurrents can deliver a critical understanding of singlet and triplet photovoltaic processes to design advanced solar‐energy materials and devices.     

Synthesis and nonlinear optical properties of PMMA copolymers having novel benzoxazole chromophores attached with various electron-withdrawing groups

For improvements of thermal stability and nonlinear optical (NLO) activity of chromophores, we newly synthesized a series of NLO chromophores incorporating aromatic benzoxazole unit as a π-conjugated bridge with various electron-withdrawing groups, such as nitrophenyl, nitrothiophene, nitrofuran, dicyanovinylphenyl, and nitrophenylethenyl group. Polymethylmethacrylate copolymers (PMBz) containing these benzoxazole chromophores were synthesized and their properties were investigated by thermogravimetry and ultraviolet-visible spectroscopy. The PMBz copolymers exhibited better thermal and ultraviolet stabilities than the corresponding copolymer with general stilbene chromophores (PMSt). Moreover, temporal stability of nonlinear optical coefficient (d₃₃) of PMBz copolymer increased in comparison with that of PMSt. The copolymer with benzoxazole–nitrothiophene chromophores had the largest d₃₃ value of 153 pm/V (at 1.064 mm) and nonresonant d₃₃ calculated by the two-level model was 21.3 pm/V.     

基于分解技术的动态结构神经网络

本文提出了基于分解技术的动态结构神经网络算法，这种算法能通过分析网络输入输出了空间的维数，确定每一隐含层神经元数目，为了加快学习效率，采用变误差混学习算法，仿真结果验证了这种算法的有效性。     

Determination of molecular, atomic, electronic cross-sections and effective atomic number of some boron compounds and TSW

The transmission of gamma-rays of some boron compounds (H₃BO₃, Na₂B₄O₇) and the trommel sieve waste (TSW) have been measured by using an extremely narrow-collimated-beam transmission method in the energy range 15.74-40.93 keV. Molecular, atomic and electronic cross-sections and effective atomic numbers have been determinated on the basis of mixture rule and compared with the results obtained from theory.     

Interlayer-free nanostructured La0.58Sr0.4Co0.2 Fe0.8O3−δ cathode on scandium stabilized zirconia electrolyte for intermediate-temperature solid oxide fuel cells

LSCF powders with a specific surface area of 25.2 m² g⁻¹ and an average particle size of 89 nm are synthesized by the polymerizable complex method. The use of nanocrystalline LSCF powders allows the fabrication of an interlayer-free nanoporous cathode on top of an ScSZ electrolyte at a low temperature at which non-electrocatalytic secondary phases cannot form. The electrochemical performance of the interlayer-free cathode depends largely on the sintering temperature. A cathode sintered at below 750 °C lacks sufficient mechanical adhesion to the electrolyte, while the electrode surfaces are locally densified when sintered at above 800 °C. Impedance spectroscopy combined with microstructural evidence reveals that the optimum sintering temperature for LSCF is 750 °C. This avoids excess densification and grain growth, and results in the lowest polarization resistance (0.048 Ω cm² at 750 °C).     

Predictive Model of Hydrogen Sulfide Absorption by Chelate Solution in a Venturi Scrubber

In the present study, a simple model was used to predict the removal efficiency of a venturi scrubber for H₂S absorption into a ferric chelate solution. From momentum and mass balances in the scrubber, a set of first‐order, nonlinear ordinary differential equations relating predominantly the liquid velocity with the H₂S concentration in the liquid along the axial direction in the scrubber were formulated. These relationships were numerically solved to give performance profiles. The validity of the model was examined by comparing the results of the model with experimental data from the working laboratory scale. The results predicted from the model are in good agreement with the experimental data obtained in different sizes of the venturi scrubber and operating variables.     

Antifriction plastic greases based on intermediate products of oil refining and liquid crystalline compounds

The rheological and triboengineering properties are presented of hydrated calcium plastic greases based on intermediate products of oil refining (hydrofined vacuum gas oil and vacuum distillate). It is shown that application of liquid crystalline cholesterol compounds as an additional component of the dispersion medium of plastic greases permits significant reduction of the wear and losses for friction and boosts the load—bearing capacity of tribocouples.     

Effects of growth rate and temperature gradient on the microstructure parameters in the directionally solidified succinonitrile–7.5 wt.% carbon tetrabromide alloy

Succinonitrile (SCN)–7.5 wt.% carbon tetrabromide (CTB) alloy was unidirectionally solidified with a constant growth rate (V = 33 μm/s) at five different temperature gradients (G = 4.1–7.6 K/mm) and with a constant temperature gradient (G = 7.6 K/mm) at five different growth rates (V = 7.2–116.7 μm/s). The primary dendrite arm spacings, secondary dendrite arm spacings, dendrite tip radius and mushy zone depths were measured. Theoretical models for the microstructure parameters have been compared with the experimental observations, and a comparison of our results with the current theoretical models and previous experimental results have also been made.     

Synthesis of derivatives of Naphtol AS containing polar groups and modification used for C.I. Pigment Red 57

The synthesis of derivatives of Naphtol AS containing polar groups (–COOH, –SO₃H) and factors affecting the reaction have been studied. Four derivatives of Naphtol AS containing –COOH or –SO₃H groups in the 3- or 4- position of the phenyl ring were synthesized. Derivatives of Naphtol AS as the second coupling component were used in mixed coupling and the effect of its added amount on the colour strength, hue, flowability and dispersing extent (in water) of pigments was studied.