Manipulation of the Open‐Circuit Voltage of Organic Solar Cells by Desymmetrization of the Structure of Acceptor–Donor–Acceptor Molecules

The synthesis of acceptor–donor–acceptor (A–D–A) molecules based on a septithiophene chain with terminal electron acceptor groups is reported. Using a dicyanovinyl‐ (DCV) substituted molecule as reference, another symmetrical A–D–A donor containing thiobarbituric (TB) groups is synthesized and these two acceptor groups are combined to produce the unsymmetrical A–D–A′ compound. The electronic properties of the donors are analyzed by cyclic voltammetry and UV‐Vis absorption spectroscopy and their photovoltaic properties are characterized on bilayer planar heterojunction cells that include spun‐cast donor films and vacuum‐deposited C₆₀ as acceptor. Optical and electrochemical data show that replacement of DCV by TB leads to a small increase of the HOMO level and to a larger decrease of the LUMO, which result in a reduced band‐gap. The desymmetrized compound presents the lowest oxidation potential in solution but the highest oxidation onset in the solid state, which leads to a significant increase of the open‐circuit voltage of the resulting solar cells.     

Finite field division based on recursive division algorithm andcomposite fields

A new division scheme for GF(2^m) is presented. This scheme is based on the recursive division algorithm and composite fields of the form GF(2²ⁿ) (m=2n). The new division scheme offers reduced time complexity of approximately O(2ⁿ) when compared to traditional bit-serial architectures with O(2²ⁿ). The scheme also offers lower hardware requirements when compared to bit-parallel architectures. The circuit architecture presented supports implementation in VLSI systems due to its regular and hardware efficient structures and is therefore suited to the implementation of Reed-Solomon codecs     

Trends and volatility in Japanese patenting in the USA: An analysis of the electronics and transport industries

This paper analyses trends and volatility in patenting in USA by Japan in the electronics/electrical and motor vehicle/transport epuiqment industries. The number of patents has increased steadily, with the two industries accounting in 1997 for one-half of Japanese patents in USA. The electronics/electrical industry has been a much stronger performer, with a share of 30% of US patents, compared with 20% for motor vehicle/transport epuiqment. Using monthly data for 1975-1997, the time-varying nature of the volatility of patents registered in the USA is examined. The asymmetric AR(1)-GJR(1,1) model is found to be suitable for motor vehicle/transport epuiqment, whereas the AR(1)-GARCH(1,1) and AR(1)-GJR(1,1) models provide interesting results for electronics/electrical.     

The UK experience: Scotland

Many in the UK are ignorant of the major differences between Scots Law and English Law, similar ignorance of the differing Scottish procedures exists. The abandonment of the separate trades system, which persisted for longer in Scotland, reduced the ability of the construction professionals to appreciate Une needs of the construction industry and to be involved in the organization and project management of the works, write H. A. Gow and F. P. Fenn of Dundee Institute of Technology.     

Electrochemical characterization of chemical species formed during the electrochemical treatment of chalcopyrite in sulfuric acid

The dissolution mechanism of chalcopyrite, and the potential range in which its passivation phenomenon takes place, were studied on carbon paste electrodes with chalcopyrite (99.46% purity, +300 mesh, 53 μm size) (CPE-CP) in 1.7 mol/dm³ H₂SO₄. A sequence of anodic potential pulses was applied to the CPE-CP to characterize its electrochemical behavior. Copper ions, dissolved by the potential pulses, were determined using a mercury film electrode (MFE) and the anodic stripping voltammetry (ASV) on a vitreous carbon disk. In addition, the modified surface of CPE-CP was characterized, before and after the potential pulses, by cyclic voltammetry (CV). The characterization of the final surface state of each electrochemically modified CPE-CP and the amount of dissolved copper showed five potential regions where the chalcopyrite dissolution mechanism changed. The initial dissolution occurs at 0.615 V ≤ E_anod < 1.015 V versus SHE forming a non-stoichiometric polysulfide (Cu_1−rFe_1−sS_2−t). The absence of copper ions in the solution indicates a passive sulfide. However, at 1.015 V ≤ E_anod < 1.085 V versus SHE, the passive product decomposes forming porous layers of non-stoichiometric polysulfide (Cu_1−xFe_1−yS_2−z) that allow the diffusional transport of charged species and the dissolution of the mineral. In the region of 1.085 V ≤ E_anod < 1.165 V versus SHE, formation covellite (CuS) was identified. At E > 1.165 V versus SHE, CuS is unstable and gives rise to complete dissolution of the chalcopyrite. Due to the experimental conditions, the mineral dissolution is inhibited by possible jarosite precipitation.     

Synthesis and antitumor molecular mechanism of agents based on amino 2-(3',4',5'-trimethoxybenzoyl)benzo[b]furan: inhibition of tubulin and induction of apoptosis

Induction of apoptosis is a promising strategy that could lead to the discovery of new molecules active in cancer chemotherapy. This property is generally observed when cells are treated with agents that target microtubules, dynamic structures that play a crucial role in cell division. Small molecules such as benzo[b]furans are attractive as inhibitors of tubulin polymerization. A new class of inhibitors of tubulin polymerization based on the 2-(3',4',5'-trimethoxybenzoyl)benzo[b]furan molecular skeleton, with the amino group placed at different positions on the benzene ring, were synthesized and evaluated for antiproliferative activity, inhibition of tubulin polymerization, and cell-cycle effects. The methoxy substitution pattern on the benzene portion of the benzo[b]furan moiety played an important role in affecting antiproliferative activity. In the series of 5-amino derivatives, the greatest inhibition of cell growth occurred if the methoxy substituent is placed at the C6 position, whereas C7 substitution decreases potency. The most promising compound in this series is 2-(3',4',5'-trimethoxybenzoyl)-3-methyl-5-amino-6-methoxybenzo[b]furan (3 h), which inhibits cancer cell growth at nanomolar concentrations (IC(50) =16-24 nM), and interacts strongly with tubulin by binding to the colchicine site. Sub-G(1) apoptotic cells in cultures of HL-60 and U937 cells were observed by flow cytometric analysis after treatment with 3 h in a concentration-dependent manner. We also show that compound 3 h induces apoptosis by activation of caspase-3, -8, and -9, and this is associated with cytochrome c release from mitochondria. The introduction of an α-bromoacryloyl group increased antiproliferative activity with respect to the parent amino derivatives.     

Photocatalytic properties of PMMA‐TiO2 class I and class II hybrid nanofibers obtained by electrospinning

The preparation, characterization, and photocatalytic activity evaluation of three hybrid fibrous materials composed mainly by poly(methyl methacrylate) (PMMA), methyl methacrylate (MMA): 3‐(trimethoxysilyl) propyl methacrylate (TMSPM): titanium butoxide (TBT), TiO₂ nanoparticles (NPTiO₂), and TiO₂ nanowires (NWTiO₂) is studied. Two types of fibe?s structures were prepared, single and core‐shell structures. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis showed both structures, single and core‐shell, as well as the inorganic phase were dispersed in the hybrid fibers. Infrared spectroscopic analysis (FT‐IR) and thermal analysis showed the organic and inorganic components, as well as the weight percentage of the inorganic phase present in hybrid fibers. The photocatalytic activity of the hybrid fibers class I and II showed that the best photodegradative efficiency for methylene blue in aqueous solution (2.9 × 10^?5 M) was 95%, provided by PMMA—10 wt % NPTiO₂. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44334.