We examined sub-nanosecond timescale charge carrier dynamics in crystalline films of a functionalized anthradithiophene (ADT) donor (D) with three different acceptor (A) molecules. A four-fold enhancement in ultrafast charge carrier separation efficiency was observed in D/A blends with a fullerene acceptor added at 7-10 wt. % concentrations, whereas a gradual decrease in peak photocurrent amplitude with acceptor concentration was observed with functionalized pentacene and indenofluorene acceptors. The results were directly correlated with the ADT-tri(ethylsilyl)ethynyl-F donor crystallinity. In the bestperforming blends, the presence of crystalline acceptor domains was also established.

We report on the dependence of time-resolved photoluminescence (PL) and photocurrent in small-molecule bulk heterojunctions on the donor–acceptor (D/A) LUMO offset, D/A separation, and acceptor domain structure. We chose a high-performance functionalized fluorinated anthradithiophene (ADT) derivative, ADT-TES-F, as the donor and two other fluorinated ADT derivatives, ADT-R-F (where R is a variable side group), as well as two functionalized fluorinated pentacene (Pn) derivatives, Pn-R-F8, as acceptors. The choice of ADT and Pn acceptors enabled us to separate the effects of the D/A LUMO offset, which was approximately zero in the case of ADT acceptors and ∼0.55 eV in the case of Pn acceptors, from those of molecular packing on the optoelectronic properties. The acceptor side groups R were chosen based on (i) packing motifs in the solid state and (ii) size, to achieve different D/A separations at the D/A interface. Addition of an ADT-R-F acceptor to the ADT-TES-F donor introduced disorder, which resulted in increased PL emission, depending on the acceptor’s packing motif, and in reduced photocurrents. In ADT-TES-F/Pn-R-F8 films, charge transfer from ADT-TES-F to Pn-R-F8 was observed with an acceptor packing-dependent formation of an exciplex, which dissociated under applied electric field, contributing to charge carrier photogeneration. However, this contribution was not sufficient to compensate for a photocurrent reduction due to an increased disorder at Pn-R-F8 concentrations of 7 wt % and above, regardless of the acceptor’s R-groups and packing motifs.

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BackgroundFacebook, a popular social networking site, has been used by people of different ages and professions for various purposes. Its use in the field of medical education is increasing dramatically. At the same time, the pros and cons of facebook use among the health science students has attracted the attention of educators. The data regarding its use and the effect on the life of Nepalese health science students has not yet been documented. Therefore, this study is carried out to evaluate the effect of facebook use on social interactions, behaviour, academics, and the health of students in a medical college of Nepal.ResultsA cross-sectional descriptive study conducted among medical, dental, nursing and allied health science students using self-administered questionnaire. The study showed that 98.2 % of participants were facebook users. Among 452 respondents, 224 and 228 were male and female respectively, with a mean age of 20.2 ± 1.2 years. The main reason for using facebook was to remain in contact with family and friend (32 %), while its use for the academic purpose was only 5 %. However, 80.8 % of students acknowledged ease in acquiring academic materials from others, through facebook. One-fourth of the students acknowledged that they are using facebook late at night on a regular basis, while surprisingly 4.2 % of the students admitted accessing facebook during the classroom lectures. Almost two-third of the users, further admitted that facebook has had a negative impact on their studies. Burning eyes (21 %), disturbed sleep (19 %), and headache (16 %) were the most common adverse health effects reported by the facebook users. Many students (71.4 %) tried and most of them (68.7 %) succeeded, in reducing time spent on facebook, to allow for increased time devoted to their studies.ConclusionThe widespread use of facebook among the health science students, was found to have both positive and negative effects on their academics, social life, and health.

The newly developed regression equations are more accurate for prediction of width of unerupted permanent teeth in a Nepalese population. Further studies are required based on larger sample size, to confirm the applicability of the new regression equations proposed.

Polyfluorenes (PFs) represent a unique class of poly para-phenylene based blue-emitting polymers with intriguing structure-property relationships. Slight variations in the choice of functionalizing side chains result in dramatic differences in the inter-and intra-chain structures in PFs. We present photoluminescence (PL) and Raman scattering studies of bulk samples and thin films of dioctylsubstituted PF (PF8) under hydrostatic pressure. The bulk sample was further thermally annealed at 1.9 GPa. The PL vibronics of the as-is sample red-shift at an average rate of 26 meV/GPa.The thermally annealed sample is characterized by at least two phase transitions at 1.1 GPa and 4.2 GPa, each of which has a different pressure coefficient for PL vibronics. The Huang-Rhys factor, a measure of the electron-phonon interaction, is found to increase with increasing pressures signaling a higher geometric relaxation of the electronic states. The Raman peaks harden with increasing pressures; the intra-ring C-C stretch frequency at 1600 cm −1 has a pressure coefficient of 7.2 cm −1 /GPa and exhibits asymmetric line shapes at higher pressures, characteristic of a strong electron-phonon interaction. The optical properties of PF8 under high pressure are further contrasted with those of a branched side chain substituted PF.

Introduction:Newer anticonvulsants have a neuromodulatory effect on pain perception mechanisms in a hyperexcitable and damaged nervous system.Aim:This study was designed to study the analgesic effects of gabapentin alone and in combination with lamotrigine and topiramate in experimental pain models.Materials and Methods:Adult albino mice (n=490) weighing 20–30 g and rats (n=130) weighing 100–200 g were injected intraperitoneally with gabapentin, lamotrigine, and topiramate alone and in different dose combinations. The hot-plate method, tail-flick method, capsaicin-induced mechanical hyperalgesia, and formalin assay were used to assess the antinociceptive effects.Results:Of the three antiepileptic drugs, when given separately, gabapentin was more efficacious than either topiramate or lamotrigine in all the pain models. Combination of 25 mg/kg gabapentin with 25 mg/kg topiramate was more efficacious (P<.05) than 50 mg/kg gabapentin alone in the capsaicin-induced mechanical hyperalgesia test. Similarly, 50 mg/kg gabapentin with 50 mg/kg topiramate or 5 mg/kg lamotrigine was more efficacious (P<.05) than 50 or 100 mg/kg gabapentin alone in late-phase formalin-induced behaviors.Conclusions:Combination of gabapentin with either lamotrigine or topiramate produced better results than gabapentin alone in capsaicin-induced mechanical hyperalgesia test and in late-phase formalin-induced behaviors.

We explored relationships between photophysical processes and solar cell characteristics in solution-processable bulk heterojunctions (BHJs), in particular: (1) polymer donor:fullerene acceptor:small-molecule (SM) nonfullerene acceptor, (2) polymer donor:SM donor:SM nonfullerene acceptor, and (3) SM donor:SM nonfullerene or fullerene acceptor. Addition of a nonfullerene SM acceptor to "efficient" polymer:fullerene BHJs led to a reduction in power conversion efficiency (PCE), mostly due to decreased charge photogeneration efficiency and increased disorder. By contrast, addition of an SM donor to "inefficient" polymer:SM nonfullerene acceptor BHJs led to a factor of two to three improvement in the PCE, due to improved charge photogeneration efficiency and transport. In most blends, exciplex formation was observed and correlated with a reduced short-circuit current (J sc ) without negatively impacting the open-circuit voltage (V oc ). A factor of ∼5 higher PCE was observed in SM donor:fullerene acceptor BHJs as compared to SMBHJs with the same SM donor but nonfullerene acceptor, due to enhanced charge carrier photogeneration in the blend with fullerene. Our study revealed that the HOMO and LUMO energies of molecules comprising a blend are not reliable parameters for predicting V oc of the blend, and an understanding of the photophysics is necessary for interpreting solar cell characteristics and improving the molecular design of BHJs.