[en] Both the flow boiling heat transfer characteristics and its influence factors in narrow rectangular channel were studied experimentally. The applicability of the empirical correlations for calculating boiling heat transfer was evaluated against the experimental data. The results show that the effect of the mass flux appears to be primary, the heat transfer coefficients increase with the mass flux under the same void fraction. The correlations based on conventional channels are not suitable for mini-channels very much. The LEELEE correlation based on narrow channels give better agreement than the other evaluated. (authors)

[en] The reaction mechanism of SiF₂ radical with HNCO has been investigated by the B3LYP method of density functional theory(DFT), while the geometries and harmonic vibration frequencies of reactants, intermediates, transition states and products have been calculated at the B3LYP/6-311++G^** level. To obtain more precise energy result, stationary point energies were calculated at the CCSD(T)/6-311++G^**//B3LYP/6-311++G^** level. SiF₂+HNCO→IM3→TS5→IM4→TS6→OSiF₂CNH(P3) was the main channel with low potential energy, OSiF₂CNH was the main product. The analyses for the combining interaction between SiF₂ radical and HNCO with the atom-in-molecules theory (AIM) have been performed

[en] In order to take advantage of organic and inorganic materials, we chose the polymer MEH-PPV as the luminous layer and ZnS as the electron transporting layer to prepare hybrid organic-inorganic light-emitting diodes (HOILEDs): ITO/MEH-PPV(∼70 nm)/ZnS(20 nm)/Al by thermal evaporation and spin coating. Compared with the single-layer device ITO/MEH-PPV(∼70 nm)/Al, spectral broadening and a slightly red shift are observed. Compared with the pure organic device ITO/MEH-PPV(∼70 nm)/BCP (20 nm)/Al and combined with the energy level structure diagram, it is concluded that the spectral broadening and red shift are due to the exciplex luminescence at the interface between MEH-PPV and ZnS or BCP. In addition, the hybrid inorganic-organic device shows a lower turn-on voltage, but the current efficiency is lower than that of the pure organic device with the same structure

[en] We investigate the effects of (N,N'-diphenyl)-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB) buffer layers on charge collection in inverted ZnO/MEH-PPV hybrid devices. The insertion of a 3-nm NPB thin layer enhances the efficiency of charge collection by improving charge transport and reducing the interface energy barrier, resulting in better device performances. S-shaped light J—V curve appears when the thickness of the NPB layer reaches 25 nm, which is induced by the inefficient charge extraction from MEH-PPV to Ag. Capacitance—voltage measurements are performed to further investigate the influence of the NPB layer on charge collection from both simulations and experiments. (interdisciplinary physics and related areas of science and technology)

[en] 5, 7, 12, 14-pentacenetetrone (PT), polycyclic quinone derivatives, are rich in carbonyl, which were investigated as a novel organic electrode material for supercapacitors. PT with a π conjugated system, is a flat molecule, generating strong π–π interactions between molecules. PT molecules were uniformly fixed on conductive reduced graphene oxide (rGO) through π–π interaction by one-step solvothermal method, forming a three-dimensional cross-linked PT@rGO hydrogel. This composite structure was conducive to reducing the charge transfer resistance and promoting the Faraday reaction of electrode, which achieved the superposition of electric double-layer capacitance and pseudocapacitance. Appropriate organic molecular loading can effectively improve electrochemical performance. The optimal PT@rGO electrode material displayed the specific capacitance of 433.2 F g⁻¹ at 5 mV s⁻¹ with an excellent rate capability in 1 mol l⁻¹ H₂SO₄ electrolyte. Finally, the fully pseudocapacitive asymmetric supercapacitor has been assembled by using PT@rGO as positive electrode and benz[a]anthracene-7,12-quinone (BAQ) modified rGO(BAQ/rGO)as negative electrode, which exhibited the good energy storage performance in a cell voltage of 1.8 V. (paper)

[en] The reaction mechanism between Fe⁺ in the ground state and the excited state with CO and N₂ O has been studied using the density functional theory (DFT) at UB3LYP/6-311 + G (2d) level. The geometries for reactants, the transition states and the products were completely optimized. All the transition states were verified by the vibrational analysis and the intrinsic reaction coordinate calculations. For each stationary point, the single-point energy calculations were carried out by UB3LYP/6-311 + + G (3df, 3pd) method. The potential energy curve-crossing diagrams were investigated for the state correlation between quartet and sextet states in the reaction of Fe⁺ with CO and N₂O. The results showed that this reaction is a two-step reaction and the reaction mechanism is an insertion-elimination mechanism. There are two crossing points between the quartet and the sextet potential energy surfaces (PESs), which would effectively reduce the activation energy and play a significant and beneficial role in the kinetic and thermodynamic aspects of this catalytic reaction. (authors)

[en] The reaction mechanism of singlet and triplet CCl₂ with HNCO has been investigated by B3LYP method of density function theory. The geometries and harmonic of reactants, intermediates, transition states and products have been calculated at the B3LYP/6-311++G^** level. Intermediates and transition states were confirmed by the results of vibration analysis and the IRC calculation. The energies of stationary point were calculated at G3 level. The results indicate that the reaction of singlet CCl₂ with HNCO have O-atom abstraction channel, insert N-H channel, NH abstraction channel, and triplet CCl₂ with HNCO has H-atom abstraction channel, among which singlet reaction HNCO+CCl₂→IM₃→TS2→P2 (c₂Cl₂ONH) was the main pathway with the lowest activation energy. (authors)

[en] The properties of poly(3-hexylthiophene):(6,6)-phenyl C₆₁ butyric acid methyl ester (P3HT:PCBM) organic photovoltaic devices (OPVs) with an indium tin oxide (ITO) anode treated by a KMnO₄ solution are investigated. The optimized KMnO₄ solution has a concentration of 50 mg/L, and ITO is treated for 15 min. The modification of ITO anode results in an enhancement of the power conversion efficiency (PCE) of the device, which is responsible for the increase of the photocurrent. The performance enhancement is attributed to the work function modification of the ITO substrate through the strong oxygenation of KMnO₄, and then the charge collection efficiency is improved. (interdisciplinary physics and related areas of science and technology)

[en] We study the spatiotemporal Bloch states of a high-frequency driven two-component Bose–Einstein condensate (BEC) with spin–orbit coupling (SOC) in an optical lattice. By adopting the rotating-wave approximation (RWA) and applying an exact trial-solution to the corresponding quasistationary system, we establish a different method for tuning SOC via external field such that the existence conditions of the exact particular solutions are fitted. Several novel features related to the exact states are demonstrated; for example, SOC leads to spin–motion entanglement for the spatiotemporal Bloch states, SOC increases the population imbalance of the two-component BEC, and SOC can be applied to manipulate the stable atomic flow which is conducive to control quantum transport of the BEC for different application purposes. (paper)

[en] In this work, bathocuproine (BCP) and bathophenanthroline (Bphen), commonly used in small-molecule organic solar cells (OSCs), are adopted as the buffer layers to improve the performance of the polymer solar cells (PSCs) based on poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV): [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) bulk heterojunction. By inserting BCP or Bphen between the active layer and the top cathode, all the performance parameters are dramatically improved. The power conversion efficiency is increased by about 70% and 120% with 5-nm BCP and 12-nm Bphen layers, respectively, when compared with that of the devices without any buffer layer. The performance enhancement is attributed to BCP or Bphen (i) increasing the optical field, and hence the absorption in the active layer, (ii) effectively blocking the excitons generated in MEH-PPV from quenching at organic/aluminum (Al) interface due to the large band-gap of BCP or Bphen, which results in a significant reduction in series resistance (R_s), and (iii) preventing damage to the active layer during the metal deposition. Compared with the traditional device using LiF as the buffer layer, the BCP-based devices show a comparable efficiency, while the Bphen-based devices show a much larger efficiency. This is due to the higher electron mobility in Bphen than that in BCP, which facilitates the electron transport and extraction through the buffer layer to the cathode. (interdisciplinary physics and related areas of science and technology)