Fabrication of a P3HT-ZnO Nanowires Gas Sensor Detecting Ammonia Gas

Directory of Open Access Journals (Sweden)

Chin-Guo Kuo

2017-12-01

Full Text Available In this study, an organic-inorganic semiconductor gas sensor was fabricated to detect ammonia gas. An inorganic semiconductor was a zinc oxide (ZnO nanowire array produced by atomic layer deposition (ALD while an organic material was a p-type semiconductor, poly(3-hexylthiophene (P3HT. P3HT was suitable for the gas sensing application due to its high hole mobility, good stability, and good electrical conductivity. In this work, P3HT was coated on the zinc oxide nanowires by the spin coating to form an organic-inorganic heterogeneous interface of the gas sensor for detecting ammonia gas. The thicknesses of the P3HT were around 462 nm, 397 nm, and 277 nm when the speeds of the spin coating were 4000 rpm, 5000 rpm, and 6000 rpm, respectively. The electrical properties and sensing characteristics of the gas sensing device at room temperature were evaluated by Hall effect measurement and the sensitivity of detecting ammonia gas. The results of Hall effect measurement for the P3HT-ZnO nanowires semiconductor with 462 nm P3HT film showed that the carrier concentration and the mobility were 2.7 × 1019 cm−3 and 24.7 cm2∙V−1∙s−1 respectively. The gas sensing device prepared by the P3HT-ZnO nanowires semiconductor had better sensitivity than the device composed of the ZnO film and P3HT film. Additionally, this gas sensing device could reach a maximum sensitivity around 11.58 per ppm.

Effect of high energy ions on the electrical and morphological properties of Poly(3-Hexylthiophene) (P3HT) thin film

Science.gov (United States)

Sharma, Trupti; Singhal, R.; Vishnoi, R.; Sharma, G. D.; Biswas, S. K.

2018-05-01

The spin-coated thin films of Poly(3-Hexylthiophene) (P3HT) on the glass and Si (double side polished) substrates have been irradiated with 55 MeV Si+4 swift heavy ions (SHI) at fluences in the range from 1 × 1010 to 1 × 1012 ions/cm2. Structural modifications produced by energetic ions are observed by characterization of pristine and irradiated P3HT thin films. Different techniques like high-resolution X-ray diffraction (HR-XRD), micro-Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) were used to analyze the structural changes in the material. A significant increase in crystallinity and room temperature electrical conductivity of P3HT film has been detected on exposure to the heavy ions. The observed increase in the electrical conductivity with increased fluences is explained in the light of improved ordering of polymer chains after irradiation. Mott's variable range hopping model has been used to explain the conduction mechanism in the material in the temperature range of 230-350 K. The modification in surface properties also observed using AFM analysis and contact angle measurement. It is observed that nature of the P3HT thin films remains hydrophobic after irradiation.

Degree of phase separation effects on the charge transfer properties of P3HT:Graphene nanocomposites

International Nuclear Information System (INIS)

Bkakri, R.; Kusmartseva, O.E.; Kusmartsev, F.V.; Song, M.; Bouazizi, A.

2015-01-01

Graphene layers were introduced into the matrix of regioregular poly (3-hexylthiophene-2, 5-diyl) (RR-P3HT) via solution processing in the perspective of the development of organic nanocomposites with high P3HT/Graphene interfaces areas for efficient charge transfer process. P3HT and graphene act as electrons donor and electrons acceptor materials, respectively. Spatial Fourier Transforms (FFT) and power spectral density (PSD) analysis of the AFM images show that the phase separation decreases with increasing the graphene weight ratio in the P3HT matrix. The Raman spectra of the P3HT:Graphene nanocomposites shows that the G-band of graphene shifts to low frequencies with progressive addition of graphene which proves that there is an interaction between the nanowires of P3HT and the graphene layers. We suggest that the shift of the G-band is due to electrons transfer from P3HT to graphene. The quenching of the photoluminescence (PL) intensity of P3HT with addition of graphene proves also that an electrons transfer process occurred at the P3HT/Graphene interfaces. - Highlights: • Graphene layers are elaborated from expandable graphite oxide. • The effects of the graphene doping level on the charge transfer process were studied. • The phase separation process decreases with increasing the graphene content in the P3HT matrix. • Quenching of the PL intensity is due to electrons transfer from P3HT to graphene

Influences mass concentration of P3HT and PCBM to application of organic solar cells

International Nuclear Information System (INIS)

Supriyanto, A.; Maya; Iriani, Y.; Ramelan, A. H.; Nurosyid, F; Rosa, E. S.

2016-01-01

Poly (3-hexylthiophene) (P3HT) and [6, 6] -phenyl-C61-butyric acid methyl ester (PCBM) are used for the organic solar cell applications. P3HT and PCBM act as donors and acceptors, respectively. In this study the efficiency of the P3HT: PCBM organic solar cells as function of the mass concentration of the blend P3HT: PCBM with 1, 2, 8, 16 mg/ml. Deposition P3HT:PCBM film using spin coating with a rotary speed of 2500 rpm for 10 seconds. Optical properties of absorption spectra characteristic using a UV-Visible Spectrometer Lambda 25 and electrical properties of I-V characteristic using Keithley 2602 instrument. The results of absoption spectra for P3HT:PCBM within different mass concentration obtained 500-600 nm wavelengths. The Energy-gap obtained about 1.9eV. The organic solar cells device performance were investigated using I-V cahractyeristic. For mass concentration of 1, 2, 8 and 16 mg/ml P3HT:PCBM were obtained 0.5×10 -3 %, 2.2×10 -3 %, 5.9×10 -3 %, and 6.1×10 -3 % efficiency of organics solar cells respectively. (paper)

Suppression of slow capacitance relaxation phenomenon in Pt/Ba0.3Sr0.7TiO3/Pt thin film ferroelectric structures by annealing in oxygen atmosphere

KAUST Repository

Altynnikov, A. G.; Gagarin, A. G.; Gaidukov, M. M.; Tumarkin, A. V.; Petrov, P. K.; Alford, N.; Kozyrev, A. B.

2014-01-01

The impact of oxygen annealing on the switching time of ferroelectric thin film capacitor structures Pt/Ba0.3Sr0.7TiO3/Pt was investigated. The response of their capacitance on pulsed control voltages before and after annealing was experimentally

Interplay of Nanoscale, Hybrid P3HT/ZTO Interface on Optoelectronics and Photovoltaic Cells.

Science.gov (United States)

Lai, Jian-Jhong; Li, Yu-Hsun; Feng, Bo-Rui; Tang, Shiow-Jing; Jian, Wen-Bin; Fu, Chuan-Min; Chen, Jiun-Tai; Wang, Xu; Lee, Pooi See

2017-09-27

Photovoltaic effects in poly(3-hexylthiophene-2,5-diyl) (P3HT) have attracted much attention recently. Here, natively p-type doped P3HT nanofibers and n-type doped zinc tin oxide (ZTO) nanowires are used for making not only field-effect transistors (FETs) but also p-n nanoscale diodes. The hybrid P3HT/ZTO p-n heterojunction shows applications in many directions, and it also facilitates the investigation of photoelectrons and photovoltaic effects on the nanoscale. As for applications, the heterojunction device shows a simultaneously high on/off ratio of n- and p-type FETs, gatable p-n junction diodes, tristate buffer devices, gatable photodetectors, and gatable solar cells. On the other hand, P3HT nanofibers are taken as a photoactive layer and the role played by the p-n heterojunction in the photoelectric and photovoltaic effects is investigated. It is found that the hybrid P3HT/ZTO p-n heterojunction assists in increasing photocurrents and enhancing photovoltaic effects. Through the controllable gating of the heterojunction, we can discuss the background mechanisms of photocurrent generation and photovoltaic energy harvesting.

Novel star-like surfactant as dispersant for multi-walled carbon nanotubes in aqueous suspensions at high concentration

Science.gov (United States)

Qiao, Min; Ran, Qianping; Wu, Shishan

2018-03-01

A kind of novel surfactant with star-like molecular structure and terminated sulfonate was synthesized, and it was used as the dispersant for multi-walled carbon nanotubes (CNTs) in aqueous suspensions compared with a traditional single-chained surfactant. The star-like surfactant showed good dispersing ability for multi-walled CNTs in aqueous suspensions. Surface tension analysis, total organic carbon analysis, X-ray photoelectron spectroscopy, zeta potential, dynamic light scattering and transmission electron microscopy were performed to research the effect of star-like surfactant on the dispersion of multi-walled CNTs in aqueous suspensions. With the assistance of star-like surfactant, the CNTs could disperse well in aqueous suspension at high concentration of 50 g/L for more than 30 days, while the CNTs precipitated completely in aqueous suspension after 1 day without any dispersant or after 10 days with sodium 4-dodecylbenzenesulfonic acid as dispersant.

Formation of polystyrene/poly(methyl methacrylate) heteroarm star-like nanogels from complementarily reactive well-defined diblock copolymers

Energy Technology Data Exchange (ETDEWEB)

Amamoto, Y; Otsuka, H; Takahara, A, E-mail: otsuka@ms.ifoc.kyushu-u.ac.j [Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0385 (Japan)

2009-08-01

Formation of star-like nanogels with two different arms via cross-linking reaction of complementarily reactive diblock copolymers was successfully accomplished. The two types of diblock copolymers, consisting of poly(methyl methacrylate) (PMMA) or polystyrene (PSt) block and alkoxyamine-based cross-linkable block, were prepared by atom transfer radical polymerization (ATRP) methods. The cross-linking reactions were carried out by merely heating their mixture, and traced by gel permeation chromatography (GPC) and multi-angle light scattering (MALS) measurements. The diblock copolymers were reacted in complementarily reactive systems, showing that all star-like nanogels have necessarily two types of arms as PMMA and PSt chains.

Excitons dynamics of 1-chloronaphthalene added P3HT:PC{sub 61}BM solar cells

Energy Technology Data Exchange (ETDEWEB)

Fan, Xing [Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Beijing 100044 (China); Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044 (China); Zhao, Suling, E-mail: slzhao@bjtu.edu.cn [Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Beijing 100044 (China); Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044 (China); Huang, Qingyu; Yang, Qianqian; Gong, Wei; Xu, Zheng [Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Beijing 100044 (China); Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044 (China)

2014-08-01

The charge photogeneration and recombination are comprehensively investigated in blend films based on poly(3-hexylthiophene) (P3HT) as an electron donor and [6,6]-phenyl-C 61-butyric acid methyl ester (PC{sub 61}BM) as an electron accepter. Transient absorption spectroscopy (TAS) together with absorption, photoluminescence (PL) are used respectively to measure optical properties of these blend films. In this paper, we demonstrate that solvent additive 1-chloronaphthalene (CN) has a unique influence on improving the performance of P3HT:PC{sub 61}BM heterojunction solar cell. It is observed that the absorption of additive-added blends has a higher intensity and is red-shifted than that of the P3HT:PC{sub 61}BM blend. The PL intensity increases which suggest that the conjugation length increases or the domain size of P3HT increases. Large domains with serious phase separation influence the interface area between P3HT and PC{sub 61}BM. Excitons are generated in both the P3HT phase and the PC{sub 61}BM phase. In all the film blends with or without additive, strongly bound interfacial CT states are formed by a large fraction of the excitons indicating geminate recombination may occur. It is demonstrated that in the blend with CN added the enhanced fraction of CT states comes from the more crystalline P3HT phases and the slower CT states and mobile charges decay indicates reduced recombination losses from early time recombination. - Highlights: • 1-chloronaphthalene(CN) can enhance the efficiency of P3HT:PCBM Solar Cells from charge photogeneration and recombination. • The enhanced fraction of CT states with CN added comes from the more crystalline P3HT phases and the slower CT states. • Mobile charges decay of blend with CN added indicates reduced recombination losses from early time recombination.

Charge Carrier Transport and Photogeneration in P3HT:PCBM Photovoltaic Blends

KAUST Repository

Laquai, Frederic

2015-05-03

This article reviews the charge transport and photogeneration in bulk-heterojunction solar cells made from blend films of regioregular poly(3-hexylthiophene) (RR-P3HT) and methano­fullerene (PCBM). The charge transport, specifically the hole mobility in the RR-P3HT phase of the polymer:fullerene photovoltaic blend, is dramatically affected by thermal annealing. The hole mobility increases more than three orders of magnitude and reaches a value of up to 2 × 10−4 cm2 V−1 s−1 after the thermal annealing process as a result of an improved semi-crystallinity of the film. This significant increase of the hole mobility balances the electron and hole mobilities in a photovoltaic blend in turn reducing space-charge formation, and this is the most important factor for the strong enhancement of the photovoltaic efficiency compared to an as cast, that is, non-annealed device. In fact, the balanced charge carrier mobility in RR-P3HT:PCBM blends in combination with a field- and temperature-independent charge carrier generation and greatly reduced non-geminate recombination explains the large quantum efficiencies mea­sured in P3HT:PCBM photovoltaic devices.

Photoelectric Properties of Silicon Nanocrystals/P3HT Bulk-Heterojunction Ordered in Titanium Dioxide Nanotube Arrays

Directory of Open Access Journals (Sweden)

Švrček Vladimir

2009-01-01

Full Text Available Abstract A silicon nanocrystals (Si-ncs conjugated-polymer-based bulk-heterojunction represents a promising approach for low-cost hybrid solar cells. In this contribution, the bulk-heterojunction is based on Si-ncs prepared by electrochemical etching and poly(3-hexylthiophene (P3HT polymer. Photoelectric properties in parallel and vertical device-like configuration were investigated. Electronic interaction between the polymer and surfactant-free Si-ncs is achieved. Temperature-dependent photoluminescence and transport properties were studied and the ratio between the photo- and dark-conductivity of 1.7 was achieved at ambient conditions. Furthermore the porous titanium dioxide (TiO2 nanotubes’ template was used for vertical order of photosensitive Si-ncs/P3HT-based blend. The anodization of titanium foil in ethylene glycol-based electrolyte containing fluoride ions and subsequent thermal annealing were used to prepare anatase TiO2nanotube arrays. The arrays with nanotube inner diameter of 90 and 50 nm were used for vertical ordering of the Si-ncs/P3HT bulk-heterojunction.

Study of charge transport in composite blend of P3HT and PCBM

Science.gov (United States)

Kumar, Manoj; Kumar, Sunil; Upadhyaya, Aditi; Yadav, Anjali; Gupta, Saral K.; Singh, Amarjeet

2018-05-01

Poly (3-hexylthiophene-2,5diyl) (P3HT) as donor and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) as acceptor are mostly used as active medium in polymeric electronic device. In this paper we have prepare the P3HT - PCBM based bulk hetero junction thin films by spin coating technique. The charge transport properties of P3HT:PCBM blends are investigated by the current-voltage measurements using Ag as an electron injecting electrode and ITO as a hole injecting contact. The current density v/s voltage relationships are analyzed in the backdrop of Schottky and Space charge limited current model.

The PdBI Arcsecond Whirlpool Survey (PAWS): The Role of Spiral Arms in Cloud and Star Formation

Energy Technology Data Exchange (ETDEWEB)

Schinnerer, Eva; Meidt, Sharon E.; Querejeta, Miguel [MPI for Astronomy, Königstuhl 17, D-69117, Heidelberg (Germany); Colombo, Dario [MPI for Radioastronomy, Auf dem Hgel, Bonn (Germany); Chandar, Rupali [Department of Physics and Astronomy, The University of Toledo, RO 106, Toledo, OH 43606 (United States); Dobbs, Clare L. [School of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); García-Burillo, Santiago [Observatorio Astronómico Nacional—OAN, Observatorio de Madrid Alfonso XII, 3, E-28014, Madrid (Spain); Hughes, Annie [IRAP, 9, avenue du Colonel Roche, BP 44346-31028 Toulouse cedex 4 (France); Leroy, Adam K. [Department of Astronomy, The Ohio State University, 140 W. 18th Avenue, Columbus, OH 43210 (United States); Pety, Jérôme [Institut de Radioastronomie Millimétrique, 300 Rue de la Piscine, F-38406, Saint Martin d’Hères (France); Kramer, Carsten [Instituto Radioastronomía Milimétrica, Av. Divina Pastora 7, Nucleo Central, E-18012, Granada (Spain); Schuster, Karl F. [Observatoire de Paris, 61 Avenue de l’Observatoire, F-75014, Paris (France)

2017-02-10

The process that leads to the formation of the bright star-forming sites observed along prominent spiral arms remains elusive. We present results of a multi-wavelength study of a spiral arm segment in the nearby grand-design spiral galaxy M51 that belongs to a spiral density wave and exhibits nine gas spurs. The combined observations of the (ionized, atomic, molecular, dusty) interstellar medium with star formation tracers (H ii regions, young <10 Myr stellar clusters) suggest (1) no variation in giant molecular cloud (GMC) properties between arm and gas spurs, (2) gas spurs and extinction feathers arising from the same structure with a close spatial relation between gas spurs and ongoing/recent star formation (despite higher gas surface densities in the spiral arm), (3) no trend in star formation age either along the arm or along a spur, (4) evidence for strong star formation feedback in gas spurs, (5) tentative evidence for star formation triggered by stellar feedback for one spur, and (6) GMC associations being not special entities but the result of blending of gas arm/spur cross sections in lower resolution observations. We conclude that there is no evidence for a coherent star formation onset mechanism that can be solely associated with the presence of the spiral density wave. This suggests that other (more localized) mechanisms are important to delay star formation such that it occurs in spurs. The evidence of star formation proceeding over several million years within individual spurs implies that the mechanism that leads to star formation acts or is sustained over a longer timescale.

Charge carrier transport and photogeneration in P3HT:PCBM photovoltaic blends.

Science.gov (United States)

Laquai, Frédéric; Andrienko, Denis; Mauer, Ralf; Blom, Paul W M

2015-06-01

This article reviews the charge transport and photogeneration in bulk-heterojunction solar cells made from blend films of regioregular poly(3-hexylthiophene) (RR-P3HT) and methano-fullerene (PCBM). The charge transport, specifically the hole mobility in the RR-P3HT phase of the polymer:fullerene photovoltaic blend, is dramatically affected by thermal annealing. The hole mobility increases more than three orders of magnitude and reaches a value of up to 2 × 10(-4) cm(2) V(-1) s(-1) after the thermal annealing process as a result of an improved semi-crystallinity of the film. This significant increase of the hole mobility balances the electron and hole mobilities in a photovoltaic blend in turn reducing space-charge formation, and this is the most important factor for the strong enhancement of the photovoltaic efficiency compared to an as cast, that is, non-annealed device. In fact, the balanced charge carrier mobility in RR-P3HT:PCBM blends in combination with a field- and temperature-independent charge carrier generation and greatly reduced non-geminate recombination explains the large quantum efficiencies mea-sured in P3HT:PCBM photovoltaic devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

5HT(1A) and 5HT(1B) receptors of medial prefrontal cortex modulate anxiogenic-like behaviors in rats.

Science.gov (United States)

Solati, Jalal; Salari, Ali-Akbar; Bakhtiari, Amir

2011-10-31

Medial prefrontal cortex (MPFC) is one of the brain regions which play an important role in emotional behaviors. The purpose of the present study was to evaluate the role of 5HT(1A) and 5HT(1B) receptors of the MPFC in modulation of anxiety behaviors in rats. The elevated plus maze (EPM) which is a useful test to investigate the effects of anxiogenic or anxiolytic drugs in rodents, was used. Bilateral intra-MPFC administration of 5HT(1A) receptor agonist, 8-OH-DPAT (5, 10, and 50 ng/rat) decreased the percentages of open arm time (OAT%) and open arm entries (OAE%), indicating an anxiogenic response. Moreover, administration of 5HT(1A) receptor antagonist, NAN-190 (0.25, 0.5, and 1 μg/rat) significantly increased OAT% and OAE%. Pre-treatment administration of NAN-190 (0.5 μg/rat), which was injected into the MPFC, reversed the anxiogenic effects of 8-OH-DPAT (5, 10, and 50 ng/rat). Intra-MPFC microinjection of 5HT(1B) receptor agonist, CGS-12066A (0.25, 0.5, and 1 μg/rat) significantly decreased OAT% and OAE%, without any change in locomotor activity, indicating an anxiogenic effect. However, injection of 5HT(1B) receptor antagonist, SB-224289 (0.5, 1, and 2 μg/rat) into the MPFC showed no significant effect. In conclusion, these findings suggest that 5HT(1A) and 5HT(1B) receptors of the MPFC region modulate anxiogenic-like behaviors in rats. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

VOPcPhO:P3HT composite micro-structures with nano-porous surface morphology

Energy Technology Data Exchange (ETDEWEB)

Azmer, Mohamad Izzat [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ahmad, Zubair, E-mail: zubairtarar@qu.edu.qa [Center for Advanced Materials (CAM), Qatar University, P. O. Box 2713, Doha (Qatar); Sulaiman, Khaulah, E-mail: khaulah@um.edu.my [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Touati, Farid [Department of Electrical Engineering, College of Engineering, Qatar University, P. O. Box 2713, Doha (Qatar); Bawazeer, Tahani M. [Department of Chemistry, Faculty of Applied Science, Umm Al-Qura University, Makkah (Saudi Arabia); Alsoufi, Mohammad S. [Mechanical Engineering Department, College of Engineering and Islamic Architecture, Umm Al-Qura University, Makkah (Saudi Arabia)

2017-03-31

Highlights: • VOPcPhO:P3HT micro-structures with nano-porous surface morphology have been formed. • Multidimensional structures have been formed by electro-spraying technique. • The electro-sprayed films are very promising for the humidity sensors. - Abstract: In this paper, composite micro-structures of Vanadyl 2,9,16,23-tetraphenoxy-29H,31H-phthalocyanine) (VOPcPhO) and Poly (3-hexylthiophene-2,5-diyl) (P3HT) complex with nano-porous surface morphology have been developed by electro-spraying technique. The structural and morphological characteristics of the VOPcPhO:P3HT composite films have been studied by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The multidimensional VOPcPhO:P3HT micro-structures formed by electro-spraying with nano-porous surface morphology are very promising for the humidity sensors due to the pore sizes in the range of micro to nano-meters scale. The performance of the VOPcPhO:P3HT electro-sprayed sensor is superior in term of sensitivity, hysteresis and response/recovery times as compared to the spin-coated one. The electro-sprayed humidity sensor exhibits ∼3 times and 0.19 times lower hysteresis in capacitive and resistive mode, respectively, as compared to the spin-coated humidity sensor.

One-pot synthesis of star-shaped macromolecules containing polyglycidol and poly(ethylene oxide) arms.

Science.gov (United States)

Lapienis, Grzegorz; Penczek, Stanislaw

2005-01-01

Synthesis of fully hydrophilic star-shaped macromolecules with different kinds of arms (A(x)B(y)C(z)) based on polyglycidol (PGL, A(x)) and poly(ethylene oxide) (PEO, C(z)) arms and diepoxy compounds (diglycidyl ethers of ethylene glycol (DGEG) or neopentyl glycol (DGNG) in the core, B(y)) forming the core is described. Precursors of arms were prepared by polymerization of glycidol with protected -OH groups. The first-generation stars were formed in the series of consecutive-parallel reactions of arms A(x) with diepoxy compounds (B). These first-generation stars (A(x)B(y)), having approximately O-, Mt+ groups on the cores, were used as multianionic initiators for the second generation of arms (C(z)) built by polymerization of ethylene oxide. The products with M(n) up to 10(5) and having up to approximately 40 arms were obtained. The number of arms (f) was determined by direct measurements of M(n) of the first-generation stars (M(n) of arms A(x) is known), compared with f calculated from the branching index g, determined from R(g) measured with size-exclusion chromatography (SEC) triple detection with TriSEC software. The progress of the star formation was monitored by 1H NMR and SEC. These novel water-soluble stars, having a large number of hydroxyl groups, both at the ends of PEO arms as well as within the PGL arms, can be functionalized and further used for attaching compounds of interest. This approach opens, therefore, a new way of "multiPEGylation".

Growth and morphology of aluminium contacts on P3HT films

Energy Technology Data Exchange (ETDEWEB)

Kaune, Gunar [TU Muenchen, Physik-Department, Lehrstuhl fuer Funktionelle Materialien, James-Franck-Strasse 1, 85747 Garching (Germany); Martin-Luther-Universitaet Halle-Wittenberg, Institut fuer Physik, Fachgruppe Photovoltaik, Von-Danckelmann-Platz 3, 06120 Halle (Germany); Meier, Robert; Metwalli, Ezzeldin; Koerstgens, Volker; Mueller-Buschbaum, Peter [TU Muenchen, Physik-Department, Lehrstuhl fuer Funktionelle Materialien, James-Franck-Strasse 1, 85747 Garching (Germany); Schlage, Kai; Couet, Sebastien; Roth, Stephan V. [HASYLAB, DESY, Notkestrasse 85, 22603 Hamburg (Germany)

2011-07-01

The characteristics of organic electronic devices are strongly influenced by the type and structure of the metal electrodes needed to inject or extract charge carriers. Therefore understanding of the metal growth process and its relation to the interactions at the metal-organic interface are necessary. We investigate the growth of an aluminium layer on the surface of a P3HT thin film by in-situ application of grazing incidence small-angle X-ray scattering (GISAXS). By subsequent modelling of the scattering data the structural parameters of the growing film are extracted and a growth process is found, which proceeds two-dimensional by stacking single atomic layers on top each other. This process results in a homogeneous film with a large contact area to the polymer and is explained by a strong chemical interaction between aluminium and P3HT, which suppresses clustering of the metal on the polymer surface. The diffusion of single aluminium atoms into the P3HT and the formation of an intermixing layer is revealed by X-ray reflectivity measurements.

Enhancement in light harvesting ability of photoactive layer P3HT: PCBM using CuO nanoparticles

Science.gov (United States)

Tiwari, D. C.; Dwivedi, Shailendra Kumar; Dipak, Pukhrambam; Chandel, Tarun

2018-05-01

In this paper, we have synthesized CuO nanoparticles via precipitation method and incorporated CuO nanoparticles in the P3HT-poly (3-hexyl) thiophene: PCBM-[6, 6]-phenyl-C61-butyric acid methyl ester heterogeneous blend. The ratio of P3HT to CuO in the blend was varied, while maintaining the fixed ratio of PCBM. The UV-visible absorption spectra of P3HT: PCBM photoactive layer containing different weight percentages of CuO nanoparticles showed a clear enhancement in the photo absorption of the active layer. The absorption band starts from 310 nm to 750 nm for P3HT: CuO (NPs):PCBM (0.5:0.5:1). This shows that incorporation of CuO nanoparticles leads to larger absorption band. In addition, the X-ray diffraction (XRD) shows improvement in P3HT crystallinity and the better formation of CuO nanostructures.

Discovery of a point-like source and a third spiral arm in the transition disk around the Herbig Ae star MWC 758

Science.gov (United States)

Reggiani, M.; Christiaens, V.; Absil, O.; Mawet, D.; Huby, E.; Choquet, E.; Gomez Gonzalez, C. A.; Ruane, G.; Femenia, B.; Serabyn, E.; Matthews, K.; Barraza, M.; Carlomagno, B.; Defrère, D.; Delacroix, C.; Habraken, S.; Jolivet, A.; Karlsson, M.; Orban de Xivry, G.; Piron, P.; Surdej, J.; Vargas Catalan, E.; Wertz, O.

2018-03-01

Context. Transition disks offer the extraordinary opportunity to look for newly born planets and to investigate the early stages of planet formation. Aim. In this context we observed the Herbig A5 star MWC 758 with the L'-band vector vortex coronagraph installed in the near-infrared camera and spectrograph NIRC2 at the Keck II telescope, with the aim of unveiling the nature of the spiral structure by constraining the presence of planetary companions in the system. Methods: Our high-contrast imaging observations show a bright (ΔL' = 7.0 ± 0.3 mag) point-like emission south of MWC 758 at a deprojected separation of 20 au (r = 0.''111 ± 0.''004) from the central star. We also recover the two spiral arms (southeast and northwest), already imaged by previous studies in polarized light, and discover a third arm to the southwest of the star. No additional companions were detected in the system down to 5 Jupiter masses beyond 0.''6 from the star. Results: We propose that the bright L'-band emission could be caused by the presence of an embedded and accreting protoplanet, although the possibility of it being an asymmetric disk feature cannot be excluded. The spiral structure is probably not related to the protoplanet candidate, unless on an inclined and eccentric orbit, and it could be due to one (or more) yet undetected planetary companions at the edge of or outside the spiral pattern. Future observations and additional simulations will be needed to shed light on the true nature of the point-like source and its link with the spiral arms. The reduced images (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/611/A74

Effect of Microwave Radiation on the Synthesis of Poly(3-hexylthiophene and the Subsequent Photovoltaic Performance of CdS/P3HT Solar Cells

Directory of Open Access Journals (Sweden)

C. H. García-Escobar

2016-01-01

Full Text Available Poly(3-hexylthiophene (P3HT is a semiconductor polymer that has been proved to be a good electron donor in organic or hybrid solar cells. In this work, a detailed study of P3HT synthesis in CH2Cl2 solvent by oxidative method with and without MW assistance has been conducted. Effects of synthesis process parameters on the physical properties of P3HT products and their application in hybrid CdS/P3HT photovoltaic devices were studied. It is observed that the use of MW as well as the reaction time affected the reaction yield and properties of the polymer products. It was found that, by the traditional method (without MW, the maximum yield and the properties of the polymer products were similar after 2 h or 24 h of synthesis. The optimal reaction time with MW for P3HT polymerization in CH2Cl2 solvent was 1 h, and the obtained P3HT product showed similar or better properties than those P3HT polymers synthesized by the traditional method in the same solvent. The effect of using MW during the synthesis was to increase yield and crystal size of P3HT. Larger energy conversion efficiency of ITO/CdS/P3HT/CP-Au devices was obtained when the P3HT product had higher molecular weight and head/tail-head/tail (HT-HT triad contents.

Photo-response of a P3HT:PCBM blend in metal-insulator-semiconductor capacitors

Energy Technology Data Exchange (ETDEWEB)

Devynck, M.; Rostirolla, B.; Watson, C. P.; Taylor, D. M., E-mail: d.m.taylor@bangor.ac.uk [School of Electronic Engineering, Bangor University, Dean Street, Bangor, Gwynedd LL57 1UT (United Kingdom)

2014-11-03

Metal-insulator-semiconductor capacitors are investigated, in which the insulator is cross-linked polyvinylphenol and the active layer a blend of poly(3-hexylthiophene), P3HT, and the electron acceptor [6,6]-phenyl-C{sub 61}-butyric acid methyl ester (PCBM). Admittance spectra and capacitance-voltage measurements obtained in the dark both display similar behaviour to those previously observed in P3HT-only devices. However, the photo-capacitance response is significantly enhanced in the P3HT:PCBM case, where exciton dissociation leads to electron transfer into the PCBM component. The results are consistent with a network of PCBM aggregates that is continuous through the film but with no lateral interconnection between the aggregates at or near the blend/insulator interface.

New Insights into the Molecular Dynamics of P3HT:PCBM Bulk Heterojunction: A Time-of-Flight Quasi-Elastic Neutron Scattering Study.

Science.gov (United States)

Guilbert, Anne A Y; Zbiri, Mohamed; Jenart, Maud V C; Nielsen, Christian B; Nelson, Jenny

2016-06-16

The molecular dynamics of organic semiconductor blend layers are likely to affect the optoelectronic properties and the performance of devices such as solar cells. We study the dynamics (5-50 ps) of the poly(3-hexylthiophene) (P3HT): phenyl-C61-butyric acid methyl ester (PCBM) blend by time-of-flight quasi-elastic neutron scattering, at temperatures in the range 250-360 K, thus spanning the glass transition temperature region of the polymer and the operation temperature of an OPV device. The behavior of the QENS signal provides evidence for the vitrification of P3HT upon blending, especially above the glass transition temperature, and the plasticization of PCBM by P3HT, both dynamics occurring on the picosecond time scale.

Barrier Performance of CVD Graphene Films Using a Facile P3HT Thin Film Optical Transmission Test

Directory of Open Access Journals (Sweden)

Srinivasa Kartik Nemani

2018-01-01

Full Text Available The barrier performance of CVD graphene films was determined using a poly(3-hexylthiophene (P3HT thin film optical transmission test. P3HT is a semiconducting polymer that photo-oxidatively degrades upon exposure to oxygen and light. The polymer is stable under ambient conditions and indoor lighting, enabling P3HT films to be deposited and encapsulated in air. P3HT’s stability under ambient conditions makes it desirable for an initial evaluation of barrier materials as a complimentary screening method in combination with conventional barrier tests. The P3HT test was used to demonstrate improved barrier performance for polymer substrates after addition of CVD graphene films. A layer-by-layer transfer method was utilized to enhance the barrier performance of monolayer graphene. Another set of absorption measurements were conducted to demonstrate the barrier performance of graphene and the degradation mechanism of graphene/P3HT over multiple wavelengths from 400 to 800 nm. The absorption spectra for graphene/polymer composite were simulated by solving Fresnel equations. The simulation results were found to be in good agreement with the measured absorption spectra. The P3HT degradation results qualitatively indicate the potential of graphene films as a possible candidate for medium performance barriers.

Determination of the structure, morphology and complex refractive index in ZnO-nanopencils/P3HT hybrid structures

CSIR Research Space (South Africa)

Motaung, DE

2012-08-01

Full Text Available of the base of the flower-shapes. ZnO-NPs were incorporated into the nanomorphology of P3HT and two variations of P3HT:C60 and P3HT: PCBM blended films in order to facilitate charge separation and transport. Thermo-gravimetric analysis revealed that Zn...

Determination of P3HT Trap Site Energies by Thermally Stimulated Current

Science.gov (United States)

Souza, J. F. P.; Serbena, J. P. M.; Kowalski, E. L.; Akcelrud, L. C.

2018-02-01

The thermal, electrical and morphological characterization of poly(3-hexylthiophene-2,5diyl) (P3HT) is presented and discussed. Thermal analyses revealed high glass transition, melting and degradation temperatures, indicating high stability of the polymer to annealings in the range 25-200°C. Electrical measurements were performed in spin-coated devices constructed using indium tin oxide (ITO) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) in the sandwich structure ITO/PEDOT:PSS/P3HT/Al. The devices were thermally treated at 25°C, 100°C, 150°C, and 200°C prior to the measurements. Characteristic curves of current density versus voltage showed that the injection of charge carriers is governed by tunneling at high electric fields. Hole mobility was estimated by impedance spectroscopy, showing a maximum value of 8.6 × 10-5 cm2/Vs for annealed films at 150°C. A thermally stimulated current technique was used to analyze the trap density in the P3HT and its respective energies for all devices, presenting the lowest trap density for annealed films at 150°C. Morphological features observed by atomic force microscopy showed that the 150°C thermally treated film presents the best interface condition of the four investigated annealing temperatures.

Structure analysis of adsorbed star-like polymers with GISAS and SFM

CERN Document Server

Wolkenhauer, M; Wunnicke, O; Stamm, M; Roovers, J; Krosigk, G V; Cubitt, R

2002-01-01

The lateral structures of dried adsorbed binary mixtures of star polymers were investigated. Blends of protonated and deuterated polybutadiene stars were prepared from cyclohexane solutions and adsorbed onto silicon substrates. The number of arms and the molecular weight of the arms was varied. With grazing incidence small angle scattering techniques (GISAS) and scanning force microscopy (SFM), different dominant in-plane length scales were determined. The morphology of these structures is dominated by blob-like structures created from single stars or agglomerates of star polymers. (orig.)

Star distribution in the Orion spiral arm

International Nuclear Information System (INIS)

Basharina, T.S.; Pavlovskaya, E.D.; Filippova, A.A.

1985-01-01

The structure of the Orion spiral arm is studied by numerical experiments, assuming that in each direction considered the star distribution along the line of sight is a combination of two Gaussian laws. The corresponding parameters are evaluated for four Milky Way fields; the bimodal laws now fit the observations by the chi 2 criterion. In the Orion arm the line-of-sight star densities follow asymmetric curves, steeper at the outer edge of the arm

Molecular ordering of spin-coated and electrosprayed P3HT:PCBM thin films and their applications to photovoltaic cell

Energy Technology Data Exchange (ETDEWEB)

Fukuda, Takeshi, E-mail: fukuda@fms.saitama-u.ac.jp [Department of Functional Materials Science, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570 (Japan); Toda, Asuki; Takahira, Kazuya; Suzuki, Katsumi [Department of Functional Materials Science, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570 (Japan); Liao, Yingjie [CERMAV-CNRS, UPR5301 & Grenoble Alpes University, 601 rue de la Chimie, BP53, 38041 Grenoble Cedex 9 (France); Hirahara, Miru [Department of Functional Materials Science, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570 (Japan); Saito, Masahiko; Osaka, Itaru [Emergent Molecular Function Research Group, RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198 (Japan)

2016-08-01

Poly(3-hexylthiophene-2,5-diyl) (P3HT) is one of the most popular donor polymers for organic photovoltaic cells; however, annealing-induced molecular ordering is necessary for realizing high photoconversion efficiency. In this study, the ratio of ordered-disordered P3HT Raman signals was calculated as the crystallinity parameter, which can be evaluated as the molecular ordering of P3HT. In the case of spin-coated devices, the crystallinity parameter increases with increasing annealing temperature, and this agrees with the photovoltaic performance. Furthermore, the direct molecular ordering of P3HT during electrospray deposition is reported, detailing the relation between the solvent evaporation time and the crystallinity of P3HT, and is evaluated by Raman spectroscopy and grazing incidence X-ray diffraction. To observe the solvent evaporation phenomena of the electropsray process, in situ measurement of solvent evaporation time was also successfully realized for the first time by placing a CCD camera below the substrate in electrospray deposition. The solvent evaporation time was controlled from 0.036 to 2.8 s by changing the applied voltage and solvent. By investigating the relationship between the solvent evaporation time and the molecular ordering of P3HT, the long solvent evaporation time caused the high crystallinity of P3HT. In addition, the population of P3HT crystallinity with an edge-on orientation also increased with increasing solvent evaporation time by evaluating the grazing incidence X-ray diffraction pattern, in good agreement with the estimated crystallinity from Raman spectroscopy. Finally, a photoconversion efficiency of 2.0% was achieved by electrospray deposition without post thermal annealing. - Highlights: • An orientation of P3HT was controlled due to the solvent evaporation time. • A solvent evaporation time was evaluated for the electrospray deposition. • A crystallinity parameter was evaluated from the Raman spectroscopy. • X

P3HT:PCBM-based organic solar cells : Optimisation of active layer nanostructure and interface properties

Science.gov (United States)

Kadem, Burak Yahya

Organic solar cells (OSCs) have attracted a significant attention during the last decade due to their simple processability on a flexible substrate as well as scope for large-scale production using role to role technique. Improving the performance of the organic solar cells and their lifetime stability are one of the main challenges faced by researchers in this field. In this thesis, work has been carried out using a blend of Poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-Phenyl C[61] butyric acid methyl ester (PCBM) as an active layer in the ratio of (1:1) (P3HT:PCBM). The efficiency and stability of P3HT:PCBM-based solar cells have been examined using different methods and employing novel materials such as1-[N-(2-ethoxyethyl) pent-4-ynamide] -8 (11), 15 (18), 22 (25) -tris-{2-[2-(2-ethoxyethoxy) ethoxy]-1-[2-((2- ethoxyethoxy) - ethoxy) methyl] ethyloxy} phthalocyaninato zinc (II) (ZnPc) to construct a ternary hybrid as the active layer. Controlling the morphology and crystallinity of P3HT:PCBM active layer was carried out using different solvents including chloroform (CF), chlorobenzene (CB) and dichlorobenzene (DCB) and their co-solvents in the ratio of (1:1) to dissolve the P3HT:PCBM blend. Optimum morphology and crystallinity were achieved using a co-solvent made of CB:CF with the obtained solar cell exhibiting the highest performance with PCE reaching 2.73% among other devices prepared using different solvents. Further device performance improvement was observed through optimization of active layer thickness with studied thickness falling in range 65-266 nm. Measurements of the PV characteristics of the investigated OSC devices have revealed optimum performance when active layer thickness was 95 nm with PCE=3.846%. The stability of the P3HT:PCBM-based devices on optimisation of the active layer thickness has shown a decrease in PCE of about 71% over a period of 41 days. Furthermore, P3HT has been blended with different fullerene derivatives (PC[60]BM, PC

Multi-Scale Modeling of an Integrated 3D Braided Composite with Applications to Helicopter Arm

Science.gov (United States)

Zhang, Diantang; Chen, Li; Sun, Ying; Zhang, Yifan; Qian, Kun

2017-10-01

A study is conducted with the aim of developing multi-scale analytical method for designing the composite helicopter arm with three-dimensional (3D) five-directional braided structure. Based on the analysis of 3D braided microstructure, the multi-scale finite element modeling is developed. Finite element analysis on the load capacity of 3D five-directional braided composites helicopter arm is carried out using the software ABAQUS/Standard. The influences of the braiding angle and loading condition on the stress and strain distribution of the helicopter arm are simulated. The results show that the proposed multi-scale method is capable of accurately predicting the mechanical properties of 3D braided composites, validated by the comparison the stress-strain curves of meso-scale RVCs. Furthermore, it is found that the braiding angle is an important factor affecting the mechanical properties of 3D five-directional braided composite helicopter arm. Based on the optimized structure parameters, the nearly net-shaped composite helicopter arm is fabricated using a novel resin transfer mould (RTM) process.

Thermal annealing study on P3HT: PCBM based bulk heterojunction organic solar cells using impedance spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Gollu, Sankara Rao, E-mail: sankar.gollu@gmail.com [Plastic Electronics and Energy Lab (PEEL), Department of Metallurgical Engineering and Material Science, Indian Institute of Technology Bombay, Powai, Mumbai-400076 (India); Sharma, Ramakant, E-mail: diptig@iitb.ac.in; G, Srinivas, E-mail: diptig@iitb.ac.in; Gupta, Dipti, E-mail: diptig@iitb.ac.in [Plastic Electronics and Energy Lab (PEEL) Department of Metallurgical Engineering and Material Science, Indian Institute of Technology Bombay, Powai, Mumbai-400076 (India)

2014-10-15

Recently, Thermal annealing is an important process for bulk heterojunction organic solar cells (BHJ OSCs) to improve the device efficiency and performance of the organic solar cells. Here in, we have examined the changes in the efficiency and morphology of P3HT: PCBM film according to the thermal annealing temperature to find the changes during the annealing process by measuring the optical absorption, atomic force microscope and X-ray diffraction. We also investigated the effect of different annealing process conditions (without, pre- and post-annealing) on the device performance of the inverted bulk heterojunction organic solar cells consist the structure of ITO/ ZnO / P3HT: PCBM / MoO{sub 3}/ Al by measuring AC impedance characteristics. Particularly, the power conversion efficiency (PCE), crystalline nature of the polymer, light absorption and the surface smoothness of P3HT: PCBM films are significantly improved after the annealing process. These results indicated the improvement in terms of PCE, interface smoothness between the P3HT: PCBM and MoO{sub 3} layers of the post annealed device originated from the decrease of series resistance between P3HT: PCBM layer and Al electrodes, which could be due to decrease in the effective life time of charge carriers.

The Fabrication of Bulk Heterojunction P3HT: PCBM Organic Photovoltaics

Science.gov (United States)

Darwis, D.; Sesa, E.; Farhamza, D.; Iqbal

2018-05-01

Bulk heterojunction Organic photovoltaic (OPV) devices are gaining a lot of interest due to their potential for ease of processing and lower manufacturing cost sustainable energy generation. In consequence, the number of studies into the properties and characteristics of organic solar cell devices has been increased to improving their power conversion. A further advancement over past decade has shown that improved efficiency could be obtained by mixed of poly(3 - hexylthiophene) (P3HT) and [1] – phenyl - C61-butyric acid methyl ester (PCBM) as an active layer. A series of optimizations of this P3HT: PCBM blends, such as the mixture ratio variation, the annealing treatments, and solvent treatment, have been emerged to improve the efficiency of the OPV. As a result, significant improvements were achieved. Here, we report the fabrication heterojunction devices of 2.9 % efficiency. This result has been achieved using the configuration of a typical heterojunction solar cell modules consists of layered glass/ITO/PEDOT: PSS/active layer/cathode interlayer

Well-defined 4-arm stars with hydroxy-terminated polyethylene, polyethylene-b-polycaprolactone and polyethylene-b-(polymethyl methacrylate) 2 arms

KAUST Repository

Zhang, Zhen

2016-07-20

Bis-boron-thexyl-silaboracycle was prepared by hydroboration of 1,4-bis(methyldivinylsilyl)butane with thexylborane and used to initiate the polyhomologation of dimethylsulfoxonium methylide to afford well-defined hydroxy-terminated 4-arm polyethylene (PE) stars. The synthesized PE stars were transformed to (PE-b-PCL)4 starblock copolymers via the ring-opening polymerization of ϵ-caprolactone (CL) initiated by the hydroxyl end groups of (PE-OH)4 in the presence of P2-tBu phosphazene base. Esterification of the hydroxyl groups of the OH-terminated PE star with 2,2-dichloroacetyl chloride led to (PE-Cl2)4 which was used as initiator (eight initiating atom transfer radical polymerization, ATRP, sites) for the synthesis of (PE-b-PMMA2)4 dendrimer-like stars by the ATRP of methyl methacrylate (MMA). All intermediates and final products were characterized by high temperature gel permeation chromatography and proton nuclear magnetic resonance spectroscopy. © 2016 The Royal Society of Chemistry.

Effect of light illumination and temperature on P3HT films, n-type Si, and ITO

Energy Technology Data Exchange (ETDEWEB)

Scudiero, Louis, E-mail: scudiero@wsu.edu [Chemistry Department and Material Science and Engineering Program, Washington State University, Pullman, Washington 99164 (United States); Shen, Yang [Department of Electrical and Computer Engineering, University of Virginia, 351 McCormick Road, Charlottesville, Virginia 22904 (United States); Gupta, Mool C., E-mail: mgupta@virginia.edu [Department of Electrical and Computer Engineering, University of Virginia, 351 McCormick Road, Charlottesville, Virginia 22904 (United States)

2014-02-15

The secondary electron (SE) cutoff energy region spectra are recorded before (dark), during (light) and after laser exposure (dark) for P3HT, Si, and ITO. An SE cutoff energy shift is observed when the bare n-type doped Si substrate is exposed to 532 nm light. This is attributed to the presence of a thin native oxide layer (∼1.5 nm) on Si. No energy shift is detected on the Ar sputtered clean Si. Also, no shift was observed for ITO. When exposed to light, a net SE energy cutoff shift was measured for P3HT deposited on both Si and ITO substrates at room temperature. However, no significant valence band maximum (VBM) energy shifts were measured for P3HT that was spun cast on both substrates under dark and light illumination. Furthermore, light effect was investigated at three different temperatures; 25, 70, and 160{sup o}C and it is found that for P3HT, the magnitude of the SE cutoff energy change is not only substrate dependent but also depends on temperature.

Suppression of slow capacitance relaxation phenomenon in Pt/Ba0.3Sr0.7TiO3/Pt thin film ferroelectric structures by annealing in oxygen atmosphere

KAUST Repository

Altynnikov, A. G.

2014-01-27

The impact of oxygen annealing on the switching time of ferroelectric thin film capacitor structures Pt/Ba0.3Sr0.7TiO3/Pt was investigated. The response of their capacitance on pulsed control voltages before and after annealing was experimentally measured. It was demonstrated that the annealing results in suppression of the capacitance slow relaxation processes and increase of the threshold control voltages. These structures can therefore be attractive for fabrication of fast acting microwave devices. © 2014 Author(s).

Fabrication, electrical characterization and device simulation of vertical P3HT field-effect transistors

Directory of Open Access Journals (Sweden)

Bojian Xu

2017-12-01

Full Text Available Vertical organic field-effect transistors (VOFETs provide an advantage over lateral ones with respect to the possibility to conveniently reduce the channel length. This is beneficial for increasing both the cut-off frequency and current density in organic field-effect transistor devices. We prepared P3HT (poly[3-hexylthiophene-2,5-diyl] VOFETs with a surrounding gate electrode and gate dielectric around the vertical P3HT pillar junction. Measured output and transfer characteristics do not show a distinct gate effect, in contrast to device simulations. By introducing in the simulations an edge layer with a strongly reduced charge mobility, the gate effect is significantly reduced. We therefore propose that a damaged layer at the P3HT/dielectric interface could be the reason for the strong suppression of the gate effect. We also simulated how the gate effect depends on the device parameters. A smaller pillar diameter and a larger gate electrode-dielectric overlap both lead to better gate control. Our findings thus provide important design parameters for future VOFETs.

New Insights into the Mechanisms of Photodegradation/Stabilization of P3HT:PCBM Active Layers Using Poly(3-hexyl-d13-Thiophene)

DEFF Research Database (Denmark)

Tournebize, Aurelien; Bussiere, Pierre-Olivier; Rivaton, Agnes

2013-01-01

species involved in the chain radical oxidation of P3HT is a key characteristic in the underlying mechanism. The results obtained in this work advance the understanding of active layer stability and will help improve the design of long lifetime organic solar cells thanks to the use of cutoff filter......The photo-oxidation mechanism of thin-film blends based on poly(3-hexylthiophene):phenyl-C-61-butyric acid methyl ester (P3HT:PCBM) upon irradiation with ultraviolet-visible light (UV-Vis) was studied. The use of deuterated P3HT, i.e., poly(3-hexyl-d(13)-thiophene) (P3HdT), permitted discrimination...

Molecular design of new P3HT derivatives: Adjusting electronic energy levels for blends with PCBM

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Eliezer Fernando [UNESP – Univ Estadual Paulista, POSMAT – Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, Bauru, SP (Brazil); Lavarda, Francisco Carlos, E-mail: lavarda@fc.unesp.br [UNESP – Univ Estadual Paulista, POSMAT – Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, Bauru, SP (Brazil); Faculdade de Ciências, UNESP – Univ Estadual Paulista, Departamento de Física, Av. Eng. Luiz Edmundo Carrijo Coube, 14-01, 17033-360 Bauru, SP (Brazil)

2014-12-15

An intensive search is underway for new materials to make more efficient organic solar cells through improvements in thin film morphology, transport properties, and adjustments to the energy of frontier electronic levels. The use of chemical modifications capable of modifying the electronic properties of materials already known is an interesting approach, as it can, in principle, provide a more adequate adjustment of the frontier electronic levels while preserving properties such as solubility. Based on this idea, we performed a theoretical study of poly(3-hexylthiophene) (P3HT) and 13 new derivatives obtained by substitution with electron acceptor and donor groups, in order to understand how the energy levels of the frontier orbitals are modified. The results show that it is possible to deduce the modification of the electronic levels in accordance with the substituent's acceptor/donor character. We also evaluated how the substituents influence the open circuit voltage and the exciton binding energy. - Highlights: • Prediction of P3HT derivatives properties for bulk-heterojunction solar cells. • Correlating substituent properties with electronic levels of P3HT derivatives. • Fluorinated P3HT improves open circuit voltage and stability.

Characterisation of 5-HT3C, 5-HT3D and 5-HT3E receptor subunits: evolution, distribution and function.

Science.gov (United States)

Holbrook, Joanna D; Gill, Catherine H; Zebda, Noureddine; Spencer, Jon P; Leyland, Rebecca; Rance, Kim H; Trinh, Han; Balmer, Gemma; Kelly, Fiona M; Yusaf, Shahnaz P; Courtenay, Nicola; Luck, Jane; Rhodes, Andrew; Modha, Sundip; Moore, Stephen E; Sanger, Gareth J; Gunthorpe, Martin J

2009-01-01

The 5-HT(3) receptor is a member of the 'Cys-loop' family of ligand-gated ion channels that mediate fast excitatory and inhibitory transmission in the nervous system. Current evidence points towards native 5-HT(3) receptors originating from homomeric assemblies of 5-HT(3A) or heteromeric assembly of 5-HT(3A) and 5-HT(3B). Novel genes encoding 5-HT(3C), 5-HT(3D), and 5-HT(3E) have recently been described but the functional importance of these proteins is unknown. In the present study, in silico analysis (confirmed by partial cloning) indicated that 5-HT(3C), 5-HT(3D), and 5-HT(3E) are not human-specific as previously reported: they are conserved in multiple mammalian species but are absent in rodents. Expression profiles of the novel human genes indicated high levels in the gastrointestinal tract but also in the brain, Dorsal Root Ganglion (DRG) and other tissues. Following the demonstration that these subunits are expressed at the cell membrane, the functional properties of the recombinant human subunits were investigated using patch clamp electrophysiology. 5-HT(3C), 5-HT(3D), and 5-HT(3E) were all non-functional when expressed alone. Co-transfection studies to determine potential novel heteromeric receptor interactions with 5-HT(3A) demonstrated that the expression or function of the receptor was modified by 5-HT(3C) and 5-HT(3E), but not 5-HT(3D). The lack of distinct effects on current rectification, kinetics or pharmacology of 5-HT(3A) receptors does not however provide unequivocal evidence to support a direct contribution of 5-HT(3C) or 5-HT(3E) to the lining of the ion channel pore of novel heteromeric receptors. The functional and pharmacological contributions of these novel subunits to human biology and diseases such as irritable bowel syndrome for which 5-HT(3) receptor antagonists have major clinical usage, therefore remains to be fully determined.

Mobile Charge Generation Dynamics in P3HT:PCBM Observed by Time-Resolved Terahertz Spectroscopy

DEFF Research Database (Denmark)

Cooke, D. G.; Krebs, Frederik C; Jepsen, Peter Uhd

2012-01-01

Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale.......Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale....

Mobile charge generation dynamics in P3HT: PCBM observed by time-resolved terahertz spectroscopy

DEFF Research Database (Denmark)

Cooke, D. G.; Krebs, Frederik C; Jepsen, Peter Uhd

2012-01-01

Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale.......Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale....

Wide Band-Gap 3,4-Difluorothiophene-Based Polymer with 7% Solar Cell Efficiency: an Alternative to P3HT

KAUST Repository

Wolf, Jannic Sebastian; Cruciani, Federico; El Labban, Abdulrahman; Beaujuge, Pierre

2015-01-01

We report on a wide band-gap polymer donor composed of benzo[1,2-b:4,5-b']dithiophene (BDT) and 3,4-difluorothiophene ([2F]T) units (Eopt ~2.1 eV), and show that the fluorinated analog PBDT[2F]T performs significantly better than its non-fluorinated counterpart PBDT[2H]T in BHJ solar cells with PC71BM. While control P3HT- and PBDT[2H]T-based devices yield PCEs of ca. 4% and 3% (Max.) respectively, PBDT[2F]T-based devices reach PCEs of ca. 7%, combining a large Voc of ca. 0.9 V and short-circuit current values (ca. 10.7 mA/cm2) comparable to those of the best P3HT-based control devices.

Wide Band-Gap 3,4-Difluorothiophene-Based Polymer with 7% Solar Cell Efficiency: an Alternative to P3HT

KAUST Repository

Wolf, Jannic Sebastian

2015-05-27

We report on a wide band-gap polymer donor composed of benzo[1,2-b:4,5-b\\']dithiophene (BDT) and 3,4-difluorothiophene ([2F]T) units (Eopt ~2.1 eV), and show that the fluorinated analog PBDT[2F]T performs significantly better than its non-fluorinated counterpart PBDT[2H]T in BHJ solar cells with PC71BM. While control P3HT- and PBDT[2H]T-based devices yield PCEs of ca. 4% and 3% (Max.) respectively, PBDT[2F]T-based devices reach PCEs of ca. 7%, combining a large Voc of ca. 0.9 V and short-circuit current values (ca. 10.7 mA/cm2) comparable to those of the best P3HT-based control devices.

Synthesis of Mikto-Arm Star Peptide Conjugates.

Science.gov (United States)

Koo, Jin Mo; Su, Hao; Lin, Yi-An; Cui, Honggang

2018-01-01

Mikto-arm star peptide conjugates are an emerging class of self-assembling peptide-based structural units that contain three or more auxiliary segments of different chemical compositions and/or functionalities. This group of molecules exhibit interesting self-assembly behavior in solution due to their chemically asymmetric topology. Here we describe the detailed procedure for synthesis of an ABC Mikto-arm star peptide conjugate in which two immiscible entities (a saturated hydrocarbon and a hydrophobic and lipophobic fluorocarbon) are conjugated onto a short β-sheet forming peptide sequence, GNNQQNY, derived from the Sup35 prion, through a lysine junction. Automated and manual Fmoc-solid phase synthesis techniques are used to synthesize the Mikto-arm star peptide conjugates, followed by HPLC purification. We envision that this set of protocols can afford a versatile platform to synthesize a new class of peptidic building units for diverse applications.

CHARACTERIZING SPIRAL ARM AND INTERARM STAR FORMATION

Energy Technology Data Exchange (ETDEWEB)

Kreckel, K.; Schinnerer, E.; Meidt, S. [Max Planck Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Blanc, G. A. [Departamento de Astronomía, Universidad de Chile, Camino del Observatorio 1515, Las Condes, Santiago (Chile); Groves, B. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Adamo, A. [Department of Astronomy, The Oskar Klein Centre, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden); Hughes, A., E-mail: kreckel@mpia.de [CNRS, IRAP, 9 Av. du Colonel Roche, BP 44346, F-31028 Toulouse cedex 4 (France)

2016-08-20

Interarm star formation contributes significantly to a galaxy’s star formation budget and provides an opportunity to study stellar birthplaces unperturbed by spiral arm dynamics. Using optical integral field spectroscopy of the nearby galaxy NGC 628 with VLT/MUSE, we construct H α maps including detailed corrections for dust extinction and stellar absorption to identify 391 H ii regions at 35 pc resolution over 12 kpc{sup 2}. Using tracers sensitive to the underlying gravitational potential, we associate H ii regions with either arm (271) or interarm (120) environments. Using our full spectral coverage of each region, we find that most physical properties (luminosity, size, metallicity, ionization parameter) of H ii regions are independent of environment. We calculate the fraction of H α luminosity due to the background of diffuse ionized gas (DIG) contaminating each H ii region, and find the DIG surface brightness to be higher within H ii regions than in the surroundings, and slightly higher within arm H ii regions. Use of the temperature-sensitive [S ii]/H α line ratio instead of the H α surface brightness to identify the boundaries of H ii regions does not change this result. Using the dust attenuation as a tracer of the gas, we find depletion times consistent with previous work (2 × 10{sup 9} yr) with no differences between the arm and interarm, but this is very sensitive to the DIG correction. Unlike molecular clouds, which can be dynamically affected by the galactic environment, we see fairly consistent properties of H ii regions in both arm and interarm environments. This suggests either a difference in star formation and feedback in arms or a decoupling of dense star-forming clumps from the more extended surrounding molecular gas.

Entanglements in P3HT and their influence on thin-film mechanical properties: Insights from molecular dynamics simulations

KAUST Repository

Tummala, Naga Rajesh; Risko, Chad; Bruner, Christopher; Dauskardt, Reinhold H.; Bredas, Jean-Luc

2015-01-01

Due to their inherent mechanical flexibility and stretchability, organic-based electronic devices have garnered a great deal of academic and industrial interest. Here, molecular-dynamics simulations are used to examine the molecular-scale details that govern the relationships among molecular weight, chain entanglement, persistence length, and the elastic characteristics of the widely studied π-conjugated polymer poly-(3-hexyl thiophene), P3HT. Oligomers containing at least 50 monomer units are required in the simulations to observe elastic behavior in P3HT, while much longer chains are required to ensure description of appropriate levels of entanglement: only when the molecular weight is greater than 50 kDa, that is, oligomers with approximately 400 monomer units, is truly entangled behavior observed. Interestingly, results from primitive path analysis of amorphous P3HT matches well with the observed onsets of inter-chain excitonic coherence with increased molecular weight. The simulations also indicate that the P3HT modulus saturates at 1.6 GPa for chain lengths of 50–100 monomers, a result that compares well with experimental results. This work highlights the care that needs to be taken to accurately model P3HT morphologies in relation to experimental measurements. © 2015 The Authors. Journal of Polymer Science Part B: Polymer Physics Published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015

Entanglements in P3HT and their influence on thin-film mechanical properties: Insights from molecular dynamics simulations

KAUST Repository

Tummala, Naga Rajesh

2015-04-01

Due to their inherent mechanical flexibility and stretchability, organic-based electronic devices have garnered a great deal of academic and industrial interest. Here, molecular-dynamics simulations are used to examine the molecular-scale details that govern the relationships among molecular weight, chain entanglement, persistence length, and the elastic characteristics of the widely studied π-conjugated polymer poly-(3-hexyl thiophene), P3HT. Oligomers containing at least 50 monomer units are required in the simulations to observe elastic behavior in P3HT, while much longer chains are required to ensure description of appropriate levels of entanglement: only when the molecular weight is greater than 50 kDa, that is, oligomers with approximately 400 monomer units, is truly entangled behavior observed. Interestingly, results from primitive path analysis of amorphous P3HT matches well with the observed onsets of inter-chain excitonic coherence with increased molecular weight. The simulations also indicate that the P3HT modulus saturates at 1.6 GPa for chain lengths of 50–100 monomers, a result that compares well with experimental results. This work highlights the care that needs to be taken to accurately model P3HT morphologies in relation to experimental measurements. © 2015 The Authors. Journal of Polymer Science Part B: Polymer Physics Published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015

Interfacial molecular order of conjugated polymer in P3HT:ZnO bilayer photovoltaics and its impact on device performance

KAUST Repository

Wood, Sebastian

2013-01-01

Hybrid (organic-oxide) photovoltaic device performance is highly dependent on the nature and quality of the organic-oxide interface. This work investigates the details of interfacial morphology in terms of the molecular order of poly(3-hexylthiophene) (P3HT) at the planar interface with zinc oxide (ZnO) formed by pulsed laser deposition. Resonant Raman spectroscopy is employed as a powerful morphological probe for conjugated polymers to reveal that the interfacial P3HT is disrupted during the deposition process whereas the bulk polymer shows an increase in molecular order. External quantum efficiency measurements of P3HT:ZnO bilayer devices show that this disordered P3HT region is active in photocurrent generation. © 2013 AIP Publishing LLC.

High-efficiency synthesis of dendrimer-like poly(ethylene oxide) via “arm-first” approach

KAUST Repository

Zhu, Saisai

2017-04-14

In this study, a dendrimer-like polymer based on poly(ethylene oxide) (PEO) was synthesized through a combination of anionic ring-opening polymerization (AROP) and click reaction via arm-first method. Firstly, the polymeric arm, a linear PEO with one alkynyl group and two bromo groups, was synthesized by AROP of ethylene oxide followed by functionalization with propargyl bromide and esterified with 2-bromopropionic bromide. Second, a star PEO carrying three azide groups was synthesized though AROP of ethylene oxide used 1,1,1-tris(hydrosymethyl) ethane as initiator followed esterificated with 2-bromopropionic acid and azidation. By azide–alkyne click reactions between the azide-terminated PEO star polymer and linear PEO with functionalization alkynyl group, a three generation dendrimer-like PEO, G3-PEO-24Br, was successfully synthesized. The resulting polymers were observed to have precisely controlled molecular weights and compositions with narrow molecular weight distributions.

Manipulation of extinction spectra of P3HT/PMMA medium arrays on silicon substrate containing self-assembled gold nanoparticles

International Nuclear Information System (INIS)

Wu, Ming-Chung; Chen, Shih-Wen; Li, Jia-Han; Chou, Yi; Lin, Jhih-Fong; Chen, Yang-Fang; Su, Wei-Fang

2012-01-01

In this study, we report a simple novel approach to modulate the extinction spectra of P3HT/PMMA by manipulating the medium arrays on a substrate that is coated with self-assembled gold nanoparticles. The 20 nm gold nanoparticles were synthesized and then self-assembled on the APTMS/silicon substrate surface by immersing the substrate into the gold colloid suspension. A high-resolution P3HT/PMMA photoluminescent electron beam resist was used to fabricate various square hole arrays on the substrate containing gold nanoparticles. The P3HT/PMMA medium composition causes the blue shifts in the extinction peaks of up to 40.6 nm by decreasing the period from 500 nm to 200 nm for P3HT/PMMA square hole arrays with a diameter of 100 nm. The magnitude of blue shift is directly proportional to the product of the changes of medium refractive index and the array structure factor. These peak shifts and intensity of extinction spectra for various P3HT/PMMA medium arrays are well described by the finite-difference time-domain (FDTD) simulation results. Since this simple cost-effective technique can tune the extinction spectrum of medium and adding the gold nanoparticles can give more functionalities for sensing applications, such as surface-enhanced Raman scattering (SERS), that provides good opportunities for the design and fabrication of new optoelectronic devices and sensors. Highlights: ► We can tune the extinction spectra of P3HT/PMMA by manipulating the medium arrays. ► These optical behaviors of P3HT/PMMA medium arrays are well described by FDTD simulation results. ► Adding the Au nanoparticles can give more functionalities for sensing applications.

Manipulation of extinction spectra of P3HT/PMMA medium arrays on silicon substrate containing self-assembled gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Wu, Ming-Chung [Department of Chemical and Materials Engineering, Chang Gung University, Taoyuan 333-02, Taiwan (China); Chen, Shih-Wen; Li, Jia-Han [Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei 106-17, Taiwan (China); Chou, Yi; Lin, Jhih-Fong [Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan (China); Chen, Yang-Fang [Department of Physics, National Taiwan University, Taipei 106-17, Taiwan (China); Su, Wei-Fang, E-mail: suwf@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan (China)

2012-11-15

In this study, we report a simple novel approach to modulate the extinction spectra of P3HT/PMMA by manipulating the medium arrays on a substrate that is coated with self-assembled gold nanoparticles. The 20 nm gold nanoparticles were synthesized and then self-assembled on the APTMS/silicon substrate surface by immersing the substrate into the gold colloid suspension. A high-resolution P3HT/PMMA photoluminescent electron beam resist was used to fabricate various square hole arrays on the substrate containing gold nanoparticles. The P3HT/PMMA medium composition causes the blue shifts in the extinction peaks of up to 40.6 nm by decreasing the period from 500 nm to 200 nm for P3HT/PMMA square hole arrays with a diameter of 100 nm. The magnitude of blue shift is directly proportional to the product of the changes of medium refractive index and the array structure factor. These peak shifts and intensity of extinction spectra for various P3HT/PMMA medium arrays are well described by the finite-difference time-domain (FDTD) simulation results. Since this simple cost-effective technique can tune the extinction spectrum of medium and adding the gold nanoparticles can give more functionalities for sensing applications, such as surface-enhanced Raman scattering (SERS), that provides good opportunities for the design and fabrication of new optoelectronic devices and sensors. Highlights: Black-Right-Pointing-Pointer We can tune the extinction spectra of P3HT/PMMA by manipulating the medium arrays. Black-Right-Pointing-Pointer These optical behaviors of P3HT/PMMA medium arrays are well described by FDTD simulation results. Black-Right-Pointing-Pointer Adding the Au nanoparticles can give more functionalities for sensing applications.

Temperature-dependent structural properties of P3HT films

Energy Technology Data Exchange (ETDEWEB)

Grigorian, S; Joshi, S; Pietsch, U, E-mail: grigorian@physik.uni-siegen.de [Institute of Physics, University Siegen, Walter Flex Strasse 3, D-57068, Siegen (Germany)

2010-11-15

Structural investigations of spin coated and drop cast poly(3-hexylthiophene) P3HT films have been performed under x-ray grazing incidence geometry. Drop cast films revealed to be highly oriented and crystalline and only slightly modify with the temperature. In contrast, spin coated films provided random orientational distribution of nanocrystallites and undergo significant morphological and structural changes during annealing. Interestingly, spin coated films of low and high molecular weight fractions behavior differently as a function of temperature. Crystalline domains of the low molecular weight fractions have been decreased, and, in contrast, we found an improvement of crystallinity of high molecular weight fraction with increase of the temperature.

Temperature-dependent structural properties of P3HT films

International Nuclear Information System (INIS)

Grigorian, S; Joshi, S; Pietsch, U

2010-01-01

Structural investigations of spin coated and drop cast poly(3-hexylthiophene) P3HT films have been performed under x-ray grazing incidence geometry. Drop cast films revealed to be highly oriented and crystalline and only slightly modify with the temperature. In contrast, spin coated films provided random orientational distribution of nanocrystallites and undergo significant morphological and structural changes during annealing. Interestingly, spin coated films of low and high molecular weight fractions behavior differently as a function of temperature. Crystalline domains of the low molecular weight fractions have been decreased, and, in contrast, we found an improvement of crystallinity of high molecular weight fraction with increase of the temperature.

A Molecular-Scale Understanding of Cohesion and Fracture in P3HT:Fullerene Blends

KAUST Repository

Tummala, Naga Rajesh; Bruner, Christopher; Risko, Chad; Bredas, Jean-Luc; Dauskardt, Reinhold H.

2015-01-01

mechanical flexibility, reliability, and lifetime. Here, the molecular mechanism for the initiation of cohesive failure in bulk heterojunction (BHJ) OPV active layers derived from the semiconducting polymer poly-(3-hexylthiophene) [P3HT] and two mono

Enhanced performance of hybrid solar cells using longer arms of quantum cadmium selenide tetrapods

KAUST Repository

Lee, Kyu-Sung

2011-12-01

We demonstrate that enhanced device performance of hybrid solar cells based on tetrapod (TP)-shaped cadmium selenide (CdSe) nanoparticles and conjugated polymer of poly (3-hexylthiophene) (P3HT) can be obtained by using longer armed tetrapods which aids in better spatial connectivity, thus decreasing charge hopping events which lead to better charge transport. Longer tetrapods with 10 nm arm length lead to improved power conversion efficiency of 1.12% compared to 0.80% of device having 5 nm short-armed tetrapods:P3HT photoactive blends.

Enhanced performance of hybrid solar cells using longer arms of quantum cadmium selenide tetrapods

KAUST Repository

Lee, Kyu-Sung; Kim, Inho; Gullapalli, Sravani; Wong, Michael S.; Jabbour, Ghassan E.

2011-01-01

We demonstrate that enhanced device performance of hybrid solar cells based on tetrapod (TP)-shaped cadmium selenide (CdSe) nanoparticles and conjugated polymer of poly (3-hexylthiophene) (P3HT) can be obtained by using longer armed tetrapods which aids in better spatial connectivity, thus decreasing charge hopping events which lead to better charge transport. Longer tetrapods with 10 nm arm length lead to improved power conversion efficiency of 1.12% compared to 0.80% of device having 5 nm short-armed tetrapods:P3HT photoactive blends.

Charge Carrier Transport and Photogeneration in P3HT:PCBM Photovoltaic Blends

KAUST Repository

Laquai, Fré dé ric; Andrienko, Denis; Mauer, Ralf; Blom, Paul W. M.

2015-01-01

mobility in the RR-P3HT phase of the polymer:fullerene photovoltaic blend, is dramatically affected by thermal annealing. The hole mobility increases more than three orders of magnitude and reaches a value of up to 2 × 10−4 cm2 V−1 s−1 after the thermal

Understanding the phase separation evolution in efficient P3HT:IC70BA-based bulk-heterojunction polymer solar cells

International Nuclear Information System (INIS)

Fan Xi; Guo Shishang; Fang Guojia; Li Songzhan

2013-01-01

The effects of solvent and thermal annealing on the morphology of the active layers and the photovoltaic performance of bulk-heterojunction (BHJ) polymer solar cells (PSCs) are investigated systematically, for PSCs based on a blend of poly(3-hexylthiophene) (P3HT) as a donor and indene-C 70 bisadduct (IC 70 BA) as an acceptor. IC 70 BA crystallites are found reasonably well dispersed in the P3HT matrix after spin-coating. However, the IC 70 BA crystallites coarsen in size after annealing, which are clearly evidenced by transmission electron microscopy. Simultaneously, space charge limited current measurements demonstrate that solvent and thermal annealing can improve the hole and electron mobility, which reduces charge-carrier recombination and improves charge-carrier transport in the P3HT and IC 70 BA blend layers. The corresponding current-voltage curves are measured in quantity and we propose a model to show the variation of the ordered structure of P3HT domains and IC 70 BA crystallite characteristics in the phase separation process, expressing a viewpoint on the high performance of BHJ PSCs.

Photoelectrochemical solar energy conversion based on blend of poly(3-hexylthiophene (P3HT and 1-(3-methoxycarbonyl propyl-1-phenyl [6,6]C61 (PCBM

Directory of Open Access Journals (Sweden)

Teketel Yohannes

2012-08-01

Full Text Available A solid-state photoelectrochemical solar energy conversion device based on blend of poly(3-hexylthiophene (P3HT and 1-(3-methoxycarbonylpropyl-1-phenyl[6,6]C61 (PCBM, and an amorphous poly(ethylene oxide complexed with I3-/I- redox couple has been constructed and characterized. The photoelectrochemical performance parameters of the device were compared with pure P3HT and P3HT:C60 blend solid-state photoelectrochemical cell. The current density-voltage characteristics in the dark and under white light illumination and photocurrent spectra for front and backside illuminations have been studied. An open-circuit voltage of 140 mV and a short-circuit current density of 28.4 μA/cm2 at light intensity of 100 mW/cm2; IPCE% of 1.52% for front side illumination (ITO|PEDOT and IPCE% of 0.17% for backside illumination (ITO|P3HT:PCBM at a wavelength of 510 nm were obtained. The dependence of the short-circuit current density and an open-circuit voltage on the light intensity and time have also been studied.DOI: http://dx.doi.org/10.4314/bcse.v26i2.12

Octopus-inspired multi-arm robotic swimming.

Science.gov (United States)

Sfakiotakis, M; Kazakidi, A; Tsakiris, D P

2015-05-13

The outstanding locomotor and manipulation characteristics of the octopus have recently inspired the development, by our group, of multi-functional robotic swimmers, featuring both manipulation and locomotion capabilities, which could be of significant engineering interest in underwater applications. During its little-studied arm-swimming behavior, as opposed to the better known jetting via the siphon, the animal appears to generate considerable propulsive thrust and rapid acceleration, predominantly employing movements of its arms. In this work, we capture the fundamental characteristics of the corresponding complex pattern of arm motion by a sculling profile, involving a fast power stroke and a slow recovery stroke. We investigate the propulsive capabilities of a multi-arm robotic system under various swimming gaits, namely patterns of arm coordination, which achieve the generation of forward, as well as backward, propulsion and turning. A lumped-element model of the robotic swimmer, which considers arm compliance and the interaction with the aquatic environment, was used to study the characteristics of these gaits, the effect of various kinematic parameters on propulsion, and the generation of complex trajectories. This investigation focuses on relatively high-stiffness arms. Experiments employing a compliant-body robotic prototype swimmer with eight compliant arms, all made of polyurethane, inside a water tank, successfully demonstrated this novel mode of underwater propulsion. Speeds of up to 0.26 body lengths per second (approximately 100 mm s(-1)), and propulsive forces of up to 3.5 N were achieved, with a non-dimensional cost of transport of 1.42 with all eight arms and of 0.9 with only two active arms. The experiments confirmed the computational results and verified the multi-arm maneuverability and simultaneous object grasping capability of such systems.

Improved performance of P3HT:PCBM solar cells by both anode modification and short-wavelength energy utilization using Tb(aca)3phen

International Nuclear Information System (INIS)

Zhuo Zu-Liang; Wang Yong-Sheng; He Da-Wei; Fu Ming

2014-01-01

The performance of P3HT:PCBM solar cells was improved by anode modification using spin-coated Tb(aca) 3 phen ultrathin films. The modification of the Tb(aca) 3 phen ultrathin film between the indium tin oxide (ITO) anode and the PE-DOT:PSS layer resulted in a maximum power conversion efficiency (PCE) of 2.99% compared to 2.66% for the reference device, which was due to the increase in the short-circuit current density (J sc ). The PCE improvement could be attributed to the short-wavelength energy utilization and the optimized morphology of the active layers. Tb(aca) 3 phen with its strong down-conversion luminescence properties is suitable for the P3HT:PCBM blend active layer, and the absorption region of the ternary blend films is extended into the near ultraviolet region. Furthermore, the crystallization and the surface morphology of P3HT:PCBM films were improved with the Tb(aca) 3 phen ultrathin film. The ultraviolent—visible absorption spectra, atomic force microscope (AFM), and X-ray diffraction (XRD) of the films were investigated. Both anode modification and short-wavelength energy utilization using Tb(aca) 3 phen in P3HT:PCBM solar cells led to about a 12% PCE increase. (interdisciplinary physics and related areas of science and technology)

Electron transport limitation in P3HT:CdSe nanorods hybrid solar cells.

Science.gov (United States)

Lek, Jun Yan; Xing, Guichuan; Sum, Tze Chien; Lam, Yeng Ming

2014-01-22

Hybrid solar cells have the potential to be efficient solar-energy-harvesting devices that can combine the benefits of solution-processable organic materials and the extended absorption offered by inorganic materials. In this work, an understanding of the factors limiting the performance of hybrid solar cells is explored. Through photovoltaic-device characterization correlated with transient absorption spectroscopy measurements, it was found that the interfacial charge transfer between the organic (P3HT) and inorganic (CdSe nanorods) components is not the factor limiting the performance of these solar cells. The insulating original ligands retard the charge recombination between the charge-transfer states across the CdSe-P3HT interface, and this is actually beneficial for charge collection. These cells are, in fact, limited by the subsequent electron collection via CdSe nanoparticles to the electrodes. Hence, the design of a more continuous electron-transport pathway should greatly improve the performance of hybrid solar cells in the future.

Relaxation near Supermassive Black Holes Driven by Nuclear Spiral Arms: Anisotropic Hypervelocity Stars, S-stars, and Tidal Disruption Events

Energy Technology Data Exchange (ETDEWEB)

Hamers, Adrian S. [Institute for Advanced Study, School of Natural Sciences, Einstein Drive, Princeton, NJ 08540 (United States); Perets, Hagai B., E-mail: hamers@ias.edu [Technion—Israel Institute of Technology, Haifa 32000 (Israel)

2017-09-10

Nuclear spiral arms are small-scale transient spiral structures found in the centers of galaxies. Similarly to their galactic-scale counterparts, nuclear spiral arms can perturb the orbits of stars. In the case of the Galactic center (GC), these perturbations can affect the orbits of stars and binaries in a region extending to several hundred parsecs around the supermassive black hole (SMBH), causing diffusion in orbital energy and angular momentum. This diffusion process can drive stars and binaries to close approaches with the SMBH, disrupting single stars in tidal disruption events (TDEs), or disrupting binaries, leaving a star tightly bound to the SMBH and an unbound star escaping the galaxy, i.e., a hypervelocity star (HVS). Here, we consider diffusion by nuclear spiral arms in galactic nuclei, specifically the Milky Way GC. We determine nuclear-spiral-arm-driven diffusion rates using test-particle integrations and compute disruption rates. Our TDE rates are up to 20% higher compared to relaxation by single stars. For binaries, the enhancement is up to a factor of ∼100, and our rates are comparable to the observed numbers of HVSs and S-stars. Our scenario is complementary to relaxation driven by massive perturbers. In addition, our rates depend on the inclination of the binary with respect to the Galactic plane. Therefore, our scenario provides a novel potential source for the observed anisotropic distribution of HVSs. Nuclear spiral arms may also be important for accelerating the coalescence of binary SMBHs and for supplying nuclear star clusters with stars and gas.

Stably dispersible P3HT/ZnO nanocomposites with tunable luminescence by in-situ hydrolysis and copolymerization of zinc methacrylate

International Nuclear Information System (INIS)

Zhang Lin; Li Fan; Chen Yiwang; Peng Xiaoming; Zhou Weihua

2010-01-01

In this paper, the copolymer shell with the internal hydrophobic polymethacrylate layer and the external hydrophilic poly(ethylene glycol) methyl ether groups was successfully bonded on the surface of ZnO nanocrystals through a simple sol-gel method, i.e., radical polymerization of zinc methacrylate (Zn(MA) 2 ) and poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) and hydrolysis. The prepared ZnO-poly(methacrylate-co-poly(ethylene glycol) methyl ether methacrylate) (ZnO-PPEGMA) nanocrystals showed good dispersion and smaller particle size, due to the presence of copolymer shell. The optical properties of ZnO-PPEGMA nanocrystals were characterized by ultraviolet-visible (UV-vis) spectroscopy and photoluminescence (PL) spectroscopy. The results indicated that the absorption edge and PL emission in the UV region of ZnO-PPEGMA nanocrystals appeared obvious blue-shift, due to the smaller particle size. Incorporation of ZnO-PPEGMA nanocrystals into poly(3-hexylthiophene) (P3HT) matrix, the dispersion of P3HT/ZnO-PPEGMA nanocomposites was greatly improved and the nanocomposites possessed excellent photoluminescence stability. Meanwhile, it was observed that the PL emission of P3HT/ZnO-PPEGMA nanocomposites was enhanced significantly, due to the presence of copolymer shell and the improvement of compatibility of ZnO-PPEGMA in the P3HT matrix. The results showed that the P3HT/ZnO-PPEGMA nanocomposites could be potential candidates for optical applications.

Multi-armed spirals and multi-pairs antispirals in spatial rock–paper–scissors games

Energy Technology Data Exchange (ETDEWEB)

Jiang, Luo-Luo, E-mail: jiangluoluo@gmail.com [College of Physics and Electronic Information Engineering, Wenzhou University, Wenzhou 325035 (China); College of Physics and Technology, Guangxi Normal University, Guilin, Guangxi 541004 (China); Wang, Wen-Xu [School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ 85287 (United States); Department of Physics, Beijing Normal University, Beijing 100875 (China); Lai, Ying-Cheng [School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ 85287 (United States); Department of Physics, Arizona State University, Tempe, AZ 85287 (United States); Ni, Xuan [School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ 85287 (United States)

2012-07-09

We study the formation of multi-armed spirals and multi-pairs antispirals in spatial rock–paper–scissors games with mobile individuals. We discover a set of seed distributions of species, which is able to produce multi-armed spirals and multi-pairs antispirals with a finite number of arms and pairs based on stochastic processes. The joint spiral waves are also predicted by a theoretical model based on partial differential equations associated with specific initial conditions. The spatial entropy of patterns is introduced to differentiate the multi-armed spirals and multi-pairs antispirals. For the given mobility, the spatial entropy of multi-armed spirals is higher than that of single armed spirals. The stability of the waves is explored with respect to individual mobility. Particularly, we find that both two armed spirals and one pair antispirals transform to the single armed spirals. Furthermore, multi-armed spirals and multi-pairs antispirals are relatively stable for intermediate mobility. The joint spirals with lower numbers of arms and pairs are relatively more stable than those with higher numbers of arms and pairs. In addition, comparing to large amount of previous work, we employ the no flux boundary conditions which enables quantitative studies of pattern formation and stability in the system of stochastic interactions in the absence of excitable media. -- Highlights: ► Multi-armed spirals and multi-pairs antispirals are observed. ► Patterns are predicted by computer simulations and partial differential equations. ► The spatial entropy of patterns is introduced. ► Patterns are relatively stable for intermediate mobility. ► The joint spirals with lower numbers of arms and pairs are relatively more stable.

Multi-armed spirals and multi-pairs antispirals in spatial rock–paper–scissors games

International Nuclear Information System (INIS)

Jiang, Luo-Luo; Wang, Wen-Xu; Lai, Ying-Cheng; Ni, Xuan

2012-01-01

We study the formation of multi-armed spirals and multi-pairs antispirals in spatial rock–paper–scissors games with mobile individuals. We discover a set of seed distributions of species, which is able to produce multi-armed spirals and multi-pairs antispirals with a finite number of arms and pairs based on stochastic processes. The joint spiral waves are also predicted by a theoretical model based on partial differential equations associated with specific initial conditions. The spatial entropy of patterns is introduced to differentiate the multi-armed spirals and multi-pairs antispirals. For the given mobility, the spatial entropy of multi-armed spirals is higher than that of single armed spirals. The stability of the waves is explored with respect to individual mobility. Particularly, we find that both two armed spirals and one pair antispirals transform to the single armed spirals. Furthermore, multi-armed spirals and multi-pairs antispirals are relatively stable for intermediate mobility. The joint spirals with lower numbers of arms and pairs are relatively more stable than those with higher numbers of arms and pairs. In addition, comparing to large amount of previous work, we employ the no flux boundary conditions which enables quantitative studies of pattern formation and stability in the system of stochastic interactions in the absence of excitable media. -- Highlights: ► Multi-armed spirals and multi-pairs antispirals are observed. ► Patterns are predicted by computer simulations and partial differential equations. ► The spatial entropy of patterns is introduced. ► Patterns are relatively stable for intermediate mobility. ► The joint spirals with lower numbers of arms and pairs are relatively more stable.

Tail state-assisted charge injection and recombination at the electron-collecting interface of P3HT:PCBM bulk-heterojunction polymer solar cells

Energy Technology Data Exchange (ETDEWEB)

Wang, He [Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544 (United States); Department of Electrical Engineering, Princeton University, Princeton, NJ 08544 (United States); Shah, Manas [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Ganesan, Venkat [Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712 (United States); Chabinyc, Michael L. [Materials Department, University of California Santa Barbara, CA 93106 (United States); Loo, Yueh-Lin [Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544 (United States)

2012-12-15

The systematic insertion of thin films of P3HT and PCBM at the electron- and hole-collecting interfaces, respectively, in bulk-heterojunction polymer solar cells results in different extents of reduction in device characteristics, with the insertion of P3HT at the electron-collecting interface being less disruptive to the output currents compared to the insertion of PCBM at the hole-collecting interface. This asymmetry is attributed to differences in the tail state-assisted charge injection and recombination at the active layer-electrode interfaces. P3HT exhibits a higher density of tail states compared to PCBM; holes in these tail states can thus easily recombine with electrons at the electron-collection interface during device operation. This process is subsequently compensated by the injection of holes from the cathode into these tail states, which collectively enables net current flow through the polymer solar cell. The study presented herein thus provides a plausible explanation for why preferential segregation of P3HT to the cathode interface is inconsequential to device characteristics in P3HT:PCBM bulk-heterojunction solar cells. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Uniaxial orientation of P3HT film prepared by soft friction transfer method.

Science.gov (United States)

Imanishi, Masayoshi; Kajiya, Daisuke; Koganezawa, Tomoyuki; Saitow, Ken-Ichi

2017-07-11

The realization of room-temperature processes is an important factor in the development of flexible electronic devices composed of organic materials. In addition, a simple and cost-effective process is essential to produce stable working devices and to enhance the performance of a smart material for flexible, wearable, or stretchable-skin devices. Here, we present a soft friction transfer method for producing aligned polymer films; a glass substrate was mechanically brushed with a velvet fabric and poly(3-hexylthiophene) (P3HT) solution was then spin-coated on the substrate. A P3HT film with a uniaxial orientation was obtained in air at room temperature. The orientation factor was 17 times higher than that of a film prepared using a conventional friction transfer technique at a high temperature of 120 °C. In addition, an oriented film with a thickness of 40 nm was easily picked up and transferred to another substrate. The mechanism for orientation of the film was investigated using six experimental methods and theoretical calculation, and was thereby attributed to a chemical process, i.e., cellulose molecules attach to the substrate and act as a template for molecular alignment.

Development of the morphology during functional stack build-up of P3HT:PCBM bulk heterojunction solar cells with inverted geometry.

Science.gov (United States)

Wang, Weijia; Pröller, Stephan; Niedermeier, Martin A; Körstgens, Volker; Philipp, Martine; Su, Bo; Moseguí González, Daniel; Yu, Shun; Roth, Stephan V; Müller-Buschbaum, Peter

2015-01-14

Highly efficient poly(3-hexylthiophene-2,5-diyl) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction solar cells are achieved by using an inverted geometry. The development of the morphology is investigated as a function of the multilayer stack assembling during the inverted solar cell preparation. Atomic force microscopy is used to reveal the surface morphology of each stack, and the inner structure is probed with grazing incidence small-angle X-ray scattering. It is found that the smallest domain size of P3HT is introduced by replicating the fluorine-doped tin oxide structure underneath. The structure sizes of the P3HT:PCBM active layer are further optimized after thermal annealing. Compared to devices with standard geometry, the P3HT:PCBM layer in the inverted solar cells shows smaller domain sizes, which are much closer to the exciton diffusion length in the polymer. The decrease in domain sizes is identified as the main reason for the improvement of the device performance.

Enhancement of the photovoltaic performance in P3HT: PbS hybrid solar cells using small size PbS quantum dots

Energy Technology Data Exchange (ETDEWEB)

Firdaus, Yuliar; Van der Auweraer, Mark, E-mail: mark.vanderauweraer@chem.kuleuven.be [Laboratory of Photochemistry and Spectroscopy, Division of Molecular Imaging and Photonics, Chemistry Department, KULeuven, Celestijnenlaan 200F, 2404, B-3001 Leuven (Belgium); Vandenplas, Erwin; Gehlhaar, Robert; Cheyns, David [Imec vzw, Kapeldreef 75, B-3001 Leuven (Belgium); Justo, Yolanda; Hens, Zeger [Physical Chemistry Laboratory, Ghent University, Krijgslaan 281-S3, 9000 Gent (Belgium)

2014-09-07

Different approaches of surface modification of the quantum dots (QDs), namely, solution-phase (octylamine, octanethiol) and post-deposition (acetic acid, 1,4-benzenedithiol) ligand exchange were used in the fabrication of hybrid bulk heterojunction solar cell containing poly (3-hexylthiophene) (P3HT) and small (2.4 nm) PbS QDs. We show that replacing oleic acid by shorter chain ligands improves the figures of merit of the solar cells. This can possibly be attributed to a combination of a reduced thickness of the barrier for electron transfer and an optimized phase separation. The best results were obtained for post-deposition ligand exchange by 1,4-benzenedithiol, which improves the power conversion efficiency of solar cells based on a bulk heterojunction of lead sulfide (PbS) QDs and P3HT up to two orders of magnitude over previously reported hybrid cells based on a bulk heterojunction of P3HT:PbS QDs, where the QDs are capped by acetic acid ligands. The optimal performance was obtained for solar cells with 69 wt. % PbS QDs. Besides the ligand effects, the improvement was attributed to the formation of an energetically favorable bulk heterojunction with P3HT, when small size (2.4 nm) PbS QDs were used. Dark current density-voltage (J-V) measurements carried out on the device provided insight into the working mechanism: the comparison between the dark J-V characteristics of the bench mark system P3HT:PCBM and the P3HT:PbS blends allows us to conclude that a larger leakage current and a more efficient recombination are the major factors responsible for the larger losses in the hybrid system.

Enhancement of the photovoltaic performance in P3HT: PbS hybrid solar cells using small size PbS quantum dots

International Nuclear Information System (INIS)

Firdaus, Yuliar; Van der Auweraer, Mark; Vandenplas, Erwin; Gehlhaar, Robert; Cheyns, David; Justo, Yolanda; Hens, Zeger

2014-01-01

Different approaches of surface modification of the quantum dots (QDs), namely, solution-phase (octylamine, octanethiol) and post-deposition (acetic acid, 1,4-benzenedithiol) ligand exchange were used in the fabrication of hybrid bulk heterojunction solar cell containing poly (3-hexylthiophene) (P3HT) and small (2.4 nm) PbS QDs. We show that replacing oleic acid by shorter chain ligands improves the figures of merit of the solar cells. This can possibly be attributed to a combination of a reduced thickness of the barrier for electron transfer and an optimized phase separation. The best results were obtained for post-deposition ligand exchange by 1,4-benzenedithiol, which improves the power conversion efficiency of solar cells based on a bulk heterojunction of lead sulfide (PbS) QDs and P3HT up to two orders of magnitude over previously reported hybrid cells based on a bulk heterojunction of P3HT:PbS QDs, where the QDs are capped by acetic acid ligands. The optimal performance was obtained for solar cells with 69 wt. % PbS QDs. Besides the ligand effects, the improvement was attributed to the formation of an energetically favorable bulk heterojunction with P3HT, when small size (2.4 nm) PbS QDs were used. Dark current density-voltage (J-V) measurements carried out on the device provided insight into the working mechanism: the comparison between the dark J-V characteristics of the bench mark system P3HT:PCBM and the P3HT:PbS blends allows us to conclude that a larger leakage current and a more efficient recombination are the major factors responsible for the larger losses in the hybrid system

Star-Branched Polymers (Star Polymers)

KAUST Repository

Hirao, Akira

2015-09-01

The synthesis of well-defined regular and asymmetric mixed arm (hereinafter miktoarm) star-branched polymers by the living anionic polymerization is reviewed in this chapter. In particular, much attention is being devoted to the synthetic development of miktoarm star polymers since 2000. At the present time, the almost all types of multiarmed and multicomponent miktoarm star polymers have become feasible by using recently developed iterative strategy. For example, the following well-defined stars have been successfully synthesized: 3-arm ABC, 4-arm ABCD, 5-arm ABCDE, 6-arm ABCDEF, 7-arm ABCDEFG, 6-arm ABC, 9-arm ABC, 12-arm ABC, 13-arm ABCD, 9-arm AB, 17-arm AB, 33-arm AB, 7-arm ABC, 15-arm ABCD, and 31-arm ABCDE miktoarm star polymers, most of which are quite new and difficult to synthesize by the end of the 1990s. Several new specialty functional star polymers composed of vinyl polymer segments and rigid rodlike poly(acetylene) arms, helical polypeptide, or helical poly(hexyl isocyanate) arms are introduced.

Quantification of branching in model three-arm star polyethylene

KAUST Repository

Ramachandran, Ramnath; Beaucage, Gregory B.; Rai, Durgesh K.; Lohse, David J.; Sun, Thomas; Tsou, Andy; Norman, Alexander Iain; Hadjichristidis, Nikolaos

2012-01-01

The versatility of a novel scaling approach in quantifying the structure of model well-defined 3-arm star polyethylene molecules is presented. Many commercial polyethylenes have long side branches, and the nature and quantity of these branches varies widely among the various forms. For instance, low-density polyethylene (LDPE) is typically a highly branched structure with broad distributions in branch content, branch lengths and branch generation (in hyperbranched structures). This makes it difficult to accurately quantify the structure and the inherent structure-property relationships. To overcome this drawback, model well-defined hydrogenated polybutadiene (HPB) structures have been synthesized via anionic polymerization and hydrogenation to serve as model analogues to long-chain branched polyethylene. In this article, model 3-arm star polyethylene molecules are quantified using the scaling approach. Along with the long-chain branch content in polyethylene, the approach also provides unique measurements of long-chain branch length and hyperbranch content. Such detailed description facilitates better understanding of the effect of branching on the physical properties of polyethylene. © 2012 American Chemical Society.

Quantification of branching in model three-arm star polyethylene

KAUST Repository

Ramachandran, Ramnath

2012-01-24

The versatility of a novel scaling approach in quantifying the structure of model well-defined 3-arm star polyethylene molecules is presented. Many commercial polyethylenes have long side branches, and the nature and quantity of these branches varies widely among the various forms. For instance, low-density polyethylene (LDPE) is typically a highly branched structure with broad distributions in branch content, branch lengths and branch generation (in hyperbranched structures). This makes it difficult to accurately quantify the structure and the inherent structure-property relationships. To overcome this drawback, model well-defined hydrogenated polybutadiene (HPB) structures have been synthesized via anionic polymerization and hydrogenation to serve as model analogues to long-chain branched polyethylene. In this article, model 3-arm star polyethylene molecules are quantified using the scaling approach. Along with the long-chain branch content in polyethylene, the approach also provides unique measurements of long-chain branch length and hyperbranch content. Such detailed description facilitates better understanding of the effect of branching on the physical properties of polyethylene. © 2012 American Chemical Society.

Lithium Depletion in Solar-like Stars: Effect of Overshooting Based on Realistic Multi-dimensional Simulations

Science.gov (United States)

Baraffe, I.; Pratt, J.; Goffrey, T.; Constantino, T.; Folini, D.; Popov, M. V.; Walder, R.; Viallet, M.

2017-08-01

We study lithium depletion in low-mass and solar-like stars as a function of time, using a new diffusion coefficient describing extra-mixing taking place at the bottom of a convective envelope. This new form is motivated by multi-dimensional fully compressible, time-implicit hydrodynamic simulations performed with the MUSIC code. Intermittent convective mixing at the convective boundary in a star can be modeled using extreme value theory, a statistical analysis frequently used for finance, meteorology, and environmental science. In this Letter, we implement this statistical diffusion coefficient in a one-dimensional stellar evolution code, using parameters calibrated from multi-dimensional hydrodynamic simulations of a young low-mass star. We propose a new scenario that can explain observations of the surface abundance of lithium in the Sun and in clusters covering a wide range of ages, from ˜50 Myr to ˜4 Gyr. Because it relies on our physical model of convective penetration, this scenario has a limited number of assumptions. It can explain the observed trend between rotation and depletion, based on a single additional assumption, namely, that rotation affects the mixing efficiency at the convective boundary. We suggest the existence of a threshold in stellar rotation rate above which rotation strongly prevents the vertical penetration of plumes and below which rotation has small effects. In addition to providing a possible explanation for the long-standing problem of lithium depletion in pre-main-sequence and main-sequence stars, the strength of our scenario is that its basic assumptions can be tested by future hydrodynamic simulations.

Lithium Depletion in Solar-like Stars: Effect of Overshooting Based on Realistic Multi-dimensional Simulations

International Nuclear Information System (INIS)

Baraffe, I.; Pratt, J.; Goffrey, T.; Constantino, T.; Viallet, M.; Folini, D.; Popov, M. V.; Walder, R.

2017-01-01

We study lithium depletion in low-mass and solar-like stars as a function of time, using a new diffusion coefficient describing extra-mixing taking place at the bottom of a convective envelope. This new form is motivated by multi-dimensional fully compressible, time-implicit hydrodynamic simulations performed with the MUSIC code. Intermittent convective mixing at the convective boundary in a star can be modeled using extreme value theory, a statistical analysis frequently used for finance, meteorology, and environmental science. In this Letter, we implement this statistical diffusion coefficient in a one-dimensional stellar evolution code, using parameters calibrated from multi-dimensional hydrodynamic simulations of a young low-mass star. We propose a new scenario that can explain observations of the surface abundance of lithium in the Sun and in clusters covering a wide range of ages, from ∼50 Myr to ∼4 Gyr. Because it relies on our physical model of convective penetration, this scenario has a limited number of assumptions. It can explain the observed trend between rotation and depletion, based on a single additional assumption, namely, that rotation affects the mixing efficiency at the convective boundary. We suggest the existence of a threshold in stellar rotation rate above which rotation strongly prevents the vertical penetration of plumes and below which rotation has small effects. In addition to providing a possible explanation for the long-standing problem of lithium depletion in pre-main-sequence and main-sequence stars, the strength of our scenario is that its basic assumptions can be tested by future hydrodynamic simulations.

Lithium Depletion in Solar-like Stars: Effect of Overshooting Based on Realistic Multi-dimensional Simulations

Energy Technology Data Exchange (ETDEWEB)

Baraffe, I.; Pratt, J.; Goffrey, T.; Constantino, T.; Viallet, M. [Astrophysics Group, University of Exeter, Exeter EX4 4QL (United Kingdom); Folini, D.; Popov, M. V.; Walder, R., E-mail: i.baraffe@ex.ac.uk [Ecole Normale Supérieure de Lyon, CRAL, UMR CNRS 5574, F-69364 Lyon Cedex 07 (France)

2017-08-10

We study lithium depletion in low-mass and solar-like stars as a function of time, using a new diffusion coefficient describing extra-mixing taking place at the bottom of a convective envelope. This new form is motivated by multi-dimensional fully compressible, time-implicit hydrodynamic simulations performed with the MUSIC code. Intermittent convective mixing at the convective boundary in a star can be modeled using extreme value theory, a statistical analysis frequently used for finance, meteorology, and environmental science. In this Letter, we implement this statistical diffusion coefficient in a one-dimensional stellar evolution code, using parameters calibrated from multi-dimensional hydrodynamic simulations of a young low-mass star. We propose a new scenario that can explain observations of the surface abundance of lithium in the Sun and in clusters covering a wide range of ages, from ∼50 Myr to ∼4 Gyr. Because it relies on our physical model of convective penetration, this scenario has a limited number of assumptions. It can explain the observed trend between rotation and depletion, based on a single additional assumption, namely, that rotation affects the mixing efficiency at the convective boundary. We suggest the existence of a threshold in stellar rotation rate above which rotation strongly prevents the vertical penetration of plumes and below which rotation has small effects. In addition to providing a possible explanation for the long-standing problem of lithium depletion in pre-main-sequence and main-sequence stars, the strength of our scenario is that its basic assumptions can be tested by future hydrodynamic simulations.

The Enhanced Formaldehyde-Sensing Properties of P3HT-ZnO Hybrid Thin Film OTFT Sensor and Further Insight into Its Stability

Directory of Open Access Journals (Sweden)

Huiling Tai

2015-01-01

Full Text Available A thin-film transistor (TFT having an organic–inorganic hybrid thin film combines the advantage of TFT sensors and the enhanced sensing performance of hybrid materials. In this work, poly(3-hexylthiophene (P3HT-zinc oxide (ZnO nanoparticles’ hybrid thin film was fabricated by a spraying process as the active layer of TFT for the employment of a room temperature operated formaldehyde (HCHO gas sensor. The effects of ZnO nanoparticles on morphological and compositional features, electronic and HCHO-sensing properties of P3HT-ZnO thin film were systematically investigated. The results showed that P3HT-ZnO hybrid thin film sensor exhibited considerable improvement of sensing response (more than two times and reversibility compared to the pristine P3HT film sensor. An accumulation p-n heterojunction mechanism model was developed to understand the mechanism of enhanced sensing properties by incorporation of ZnO nanoparticles. X-ray photoelectron spectroscope (XPS and atomic force microscopy (AFM characterizations were used to investigate the stability of the sensor in-depth, which reveals the performance deterioration was due to the changes of element composition and the chemical state of hybrid thin film surface induced by light and oxygen. Our study demonstrated that P3HT-ZnO hybrid thin film TFT sensor is beneficial in the advancement of novel room temperature HCHO sensing technology.

Composition-dependent phase separation effects of organic solar cells using P3HT:PCBM as active layer and chromium oxide as hole transporting layer

International Nuclear Information System (INIS)

Qin Pingli; Fang Guojia; Sun Nanhai; Fan Xi; Zheng Qiao; Chen Fei; Wan Jiawei; Zhao Xingzhong

2011-01-01

Phase separation of the poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) active layer (ATL) was investigated by varying their relative ratio in the organic solar cells (OSCs). With the help of the UV/visible spectrophotometer, optical microscopy and scanning electron microscope, we found that the cluster of PCBM at the interface or surface was affected by Al cathode, the composition of the blends and thermal annealing. The disc-like shape crystals of PCBM substituted for the needle-like ones at higher PCBM compositions at the ATL/Al interface, which led to stronger contacts and bigger contact area. It could make short circuit current density increase, but may affect the blend morphology and result in parallel resistance and open circuit voltage decreased with the PCBM ratio increasing from 40 to 60%. The microstructure of the P3HT:PCBM ATL, determined by the composition dependent phase separation, supported the optimized performance of the OSCs with the composition of 40-50% PCBM.

Methods to Directly Image Exoplanets around Alpha Centauri and Other Multi-Star Systems

Science.gov (United States)

Belikov, R.; Sirbu, D.; Bendek, E.; Pluzhnik, E.

2017-12-01

The majority of FGK stars exist as multi-star star systems, and thus form a potentially rich target sample for direct imaging of exoplanets. A large fraction of these stars have starlight leakage from their companion that is brighter than rocky planets. This is in particular true of Alpha Centauri, which is 2.4x closer and about an order of magnitude brighter than any other FGK star, and thus may be the best target for any direct imaging mission, if the light of both stars can be suppressed. Thus, the ability to suppress starlight from two stars improves both the quantity and quality of Sun-like targets for missions such as WFIRST, LUVOIR, and HabEx. We present an analysis of starlight leak challenges in multi-star systems and techniques to solve those challenges, with an emphasis on imaging Alpha Centauri with WFIRST. For the case of internal coronagraphs, the fundamental problem appears to be independent wavefront control of multiple stars (at least if the companion is close enough or bright enough that it cannot simply be removed by longer exposure times or post-processing). We present a technique called Multi-Star Wavefront Control (MSWC) as a solution to this challenge and describe the results of our technology development program that advanced MSWC to TRL 3. Our program consisted of lab demonstrations of dark zones in two-star systems, validated simulations, as well as simulated predictions demonstrating that with this technology, contrasts needed for Earth-like planets are in principle achievable. We also demonstrate MSWC in Super-Nyquist mode, which allows suppression of multiple stars at separations greater than the spatial Nyquist limit of the deformable mirror.

Acupuncture Attenuates Anxiety-Like Behavior by Normalizing Amygdaloid Catecholamines during Ethanol Withdrawal in Rats

Directory of Open Access Journals (Sweden)

Zheng Lin Zhao

2011-01-01

Full Text Available Previously, we demonstrated acupuncture at acupoint HT7 (Shen-Men attenuated ethanol withdrawal syndrome by normalizing the dopamine release in nucleus accumbens shell. In the present study, we investigated the effect of acupuncture on anxiety-like behavior in rats and its relevant mechanism by studying neuro-endocrine parameters during ethanol withdrawal. Rats were treated with 3 g kg−1day−1 of ethanol (20%, w/v or saline by intraperitoneal injections for 28 days. The rats undergoing ethanol withdrawal exhibited anxiety-like behavior 72 h after the last dose of ethanol characterized by the decrease of time spent in the open arms of the elevated plus maze compared with the saline-treated rats (P < .05. Radioimmunoassay exhibited there were notably increased concentrations of plasma corticosterone in ethanol-withdrawn rats compared with saline-treated rats (P < .05. Additionally, high performance liquid chromatography analysis also showed the levels of norepinephrine and 3-methoxy-4-hydroxy-phenylglycol were markedly increased while the levels of dopamine and 3,4-dihydroxyphenylacetic acid were significantly decreased in the central nucleus of the amygdala of ethanol-withdrawn rats compared with saline-treated rats (P < .01. Acupuncture groups were treated with acupuncture at acupoint HT7 or PC6 (Nei-Guan. Acupuncture at HT7 but not PC6 greatly attenuated the anxiety-like behavior during ethanol withdrawal as evidenced by significant increases in the percentage of time spent in open arms (P < .05. In the meantime, acupuncture at HT7 also markedly inhibited the alterations of neuro-endocrine parameters induced by ethanol withdrawal (P < .05. These results suggest that acupuncture may attenuate anxiety-like behavior during ethanol withdrawal through regulation of neuro-endocrine system.

Theoretical Study on the Rational Design of Cyano-Substituted P3HT Materials for OSCs

DEFF Research Database (Denmark)

Qiu, Meng; Brandt, Rasmus Guldbæk; Niu, Yingli

2015-01-01

Calculations have been made regarding the strong electron-withdrawing cyano (-CN) group, which was introduced onto the backbone of poly(3-hexylthiophene) (P3HT), as an effective way to improve the parameters essential for the photovoltaic performance of organic solar cells (OSCs). The substitution...... useful information for better design strategy for OSCs....

A Multi-Armed Bandit Approach to Following a Markov Chain

Science.gov (United States)

2017-06-01

Introduction to online convex optimization ,” Foundations and Trends in Optimization , vol. 2, no. 3-4, pp. 157–325, 2016. [3] A. Mahajan and D. Teneketzis...stochastic optimization , machine learning, discrete time Markov chains, stochastic Multi-Armed Bandit, combinatorial Multi-Armed Bandit, online learning, and...fulfillment of the requirements for the degree of MASTER OF SCIENCE IN OPERATIONS RESEARCH from the NAVAL POSTGRADUATE SCHOOL June 2017 Approved by: Roberto

Frequency dependence of p-mode frequency shifts induced by magnetic activity in Kepler solar-like stars

Science.gov (United States)

Salabert, D.; Régulo, C.; Pérez Hernández, F.; García, R. A.

2018-04-01

The variations of the frequencies of the low-degree acoustic oscillations in the Sun induced by magnetic activity show a dependence on radial order. The frequency shifts are observed to increase towards higher-order modes to reach a maximum of about 0.8 μHz over the 11-yr solar cycle. A comparable frequency dependence is also measured in two other main sequence solar-like stars, the F-star HD 49933, and the young 1 Gyr-old solar analog KIC 10644253, although with different amplitudes of the shifts of about 2 μHz and 0.5 μHz, respectively. Our objective here is to extend this analysis to stars with different masses, metallicities, and evolutionary stages. From an initial set of 87 Kepler solar-like oscillating stars with known individual p-mode frequencies, we identify five stars showing frequency shifts that can be considered reliable using selection criteria based on Monte Carlo simulations and on the photospheric magnetic activity proxy Sph. The frequency dependence of the frequency shifts of four of these stars could be measured for the l = 0 and l = 1 modes individually. Given the quality of the data, the results could indicate that a physical source of perturbation different from that in the Sun is dominating in this sample of solar-like stars.

Morphology Effect of Silver Nanostructures on the Performance of a P3HT:Graphene:AgNs-Based Active Layer Obtained via Dip Coating

Directory of Open Access Journals (Sweden)

Alí Gómez-Acosta

2016-01-01

Full Text Available We report the effect of the use of different silver nanostructures (AgNs layers deposited via dip coating onto a poly(3-hexylthiophene (P3HT and solution processable functionalized graphene (SPFGraphene composite film intended to be used as active layer in BHJ devices. SPFGraphene was added to P3HT in a ratio of 1.5 wt%. The best results were achieved when a layer of silver nano-pseudospheres (AgNPSs obtained after 10 immersion cycles was used as coating; in this case the highest light trapping and efficiency percent (η=0.23% were achieved. This means an increase of ~11.3% in comparison with the efficiency of the noncoated P3HT:SPFGraphene composite. Results also indicate that graphene was successfully functionalized in order to obtain appropriate dispersion in P3HT and that such conjugated polymer remained unaltered after the addition of SPFGraphene. Finally, it can be concluded that the electrical properties of the as-synthesized films are dependent on the shape and concentration of the AgNs deposited via dip coating.

The short circuit current improvement in P3HT:PCBM based polymer solar cell by introducing PSBTBT as additional electron donor.

Science.gov (United States)

Sun, Lu; Shen, Liang; Mengd, Fanxu; Xu, Peng; Guo, Wenbin; Ruan, Shengping

2014-05-01

Here we demonstrate the influence of electron-donating polymer addition on the performance of poly(3-hexylthiophene) (P3HT):1 -(3-methoxycarbonyl)-propyl-1-phenyl-(6,6) C61 (PCBM) solar cells. Poly[(4,42-bis(2-ethylhexyl) dithieno [3,2-b:22,32-d] silole)-2,6-diylalt-(2,1,3-benzothiadiazole)-4,7-diyl] (PSBTBT) was chosen as the electron-donating polymer to improve the short circuit current (J(sc)) due to its distinct absorption in the near-IR range and similar HOMO level with that of P3HT. In the study, we found that J(sc) was improved for ternary blend (P3HT:PSBTBT:PCBM) solar cells. The dependence of device performance was investigated. J(sc) got decreased with increasing the ratio of PSBTBT. Result showed that J(sc) of ternary blend solar cells was improved greatly after thermal annealing at 150 degrees C, close to that of the binary blend (PSBTBT:PCBM) solar cells.

Fabrication of polymer/cadmium sulfide hybrid solar cells [P3HT:CdS and PCPDTBT:CdS] by spray deposition.

Science.gov (United States)

Kumar, Neetesh; Dutta, Viresh

2014-11-15

This paper investigates fabrication of surfactant free CdS nanoparticles (NPs) and application in the fabrication of P3HT:CdS and PCPDTBT:CdS bulk-heterojunction hybrid solar cells using high-throughput, large-area, low cost spray deposition technique. Both the hybrid active layers and hole transport layers are deposited by spray technique. The CdS/Poly(3-hexylthiophene-2,5-diyl) (P3HT) and CdS/Poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT) hybrid devices are fabricated by spray deposition process at optimized conditions (i.e. film thickness, spray solution volume, distance between sample and spray nozzle, substrate temperature, etc.). The power conversion efficiency of η=0.6% and 1.02% is obtained for P3HT:CdS and PCPDTBT:CdS hybrid devices, respectively. Spray coating holds significant promise as a technique capable of fabricating large-area, high performance hybrid solar cells. Copyright © 2014 Elsevier Inc. All rights reserved.

Synthesis and self-assembly of four-armed star copolymer based on poly(ethylene brassylate) hydrophobic block as potential drug carries

Energy Technology Data Exchange (ETDEWEB)

Chen, Jiucun, E-mail: chenjc@swu.edu.cn; Li, Junzhi; Liu, Jianhua; Weng, Bo; Xu, Liqun [Southwest University, Institute for Clean Energy & Advanced Materials (China)

2016-05-15

A novel well-defined four-armed star poly(ethylene brassylate)-b-poly(poly(ethylene glycol)methyl ether methacrylate) (s-PEB-b-P(PEGMA)) was synthesized and self-assembled via the combination of ring-opening polymerization and reversible addition-fragmentation chain transfer polymerization (RAFT) in this work. It proceeded firstly with the synthesis of hydrophobic four-armed star homopolymer of ethylene brassylate (EB) via ROP with organic catalyst, followed by the esterification reaction of s-PEB with chain transfer agent. Afterward, RAFT polymerization of PEGMA monomer was initialed using PEB-based macro-RAFT agent, resulting in the target amphiphilic four-armed star copolymer. The obtained s-PEB-b-P(PEGMA) can assemble into micelles with PEB segments as core and P(PEGMA) segments as shell in aqueous solution. The self-assembly behavior was studied by dynamic light scattering and transmission electron microscope. The micelles of s-PEB-b-P(PEGMA) exhibited higher loading capacity of the anticancer drug doxorubicin (DOX). The investigation of DOX release from the micelles demonstrated that the release rate of the hydrophobic drug could be effectively controlled.Graphical Abstract.

Relaxation and Conductivity in P3HT/PC71BM Blends As Revealed by Dielectric Spectroscopy

DEFF Research Database (Denmark)

Cui, Jing; Martinez-Tong, Daniel E.; Sanz, Alejandro

2016-01-01

The conduction mechanism and the molecular dynamics on the paradigmatic bulk heterojunction formed by poly(3-hexylthiophene) (P3HT) and phenyl-C-71-butyric acid methyl ester (PC71BM) blends have been characterized by dielectric spectroscopy. The results show that hexyl lateral chains of the polym...

Performance and stability of P3HT/PCBM bulk heterojunction organic solar cells

Energy Technology Data Exchange (ETDEWEB)

Yumnam, Nivedita; Bom, Sidhant; Wagner, Veit [School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen (Germany)

2011-07-01

Organic photovoltaic cells are promising candidates for large-area, low-cost production of solar cells. However, the low stability in conjunction with their medium performance is one of the major drawbacks in comparison to their inorganic counterparts. In this investigation environmental conditions for degradation of bulk heterojunction P3HT/PCBM solar cells are systematically analyzed over a period of one week. Devices were prepared by spin coating from different compositions of P3HT and PCBM in Chlorobenzene (C{sub 6}H{sub 5}Cl). Performance parameters, efficiency and I-V characteristics were determined in a N{sub 2} glove box showing optimized efficiency for a 1:1 ratio. Degradation behavior in N{sub 2} atmosphere, vacuum and solvent-enriched atmosphere (Chlorobenzene) showed best results for vacuum stored solar cells while for solvent-enriched atmosphere rapid degradation was observed. Remarkable degradation (open-circuit voltage and short-circuit current reduced to 90% and 60% after one week) was also found for N{sub 2} atmosphere of the glove box used for the solar cell production. Residual solvent vapor left dispersed in the atmosphere of the glovebox after the spin coating process is identified as an important parameter of this degradation.

Enhancement of Power Efficiency and Stability of P3HT-Based Organic Solar Cells under Elevated Operating-Temperatures by Using a Nanocomposite Photoactive Layer

Directory of Open Access Journals (Sweden)

Tran Thi Thao

2015-01-01

Full Text Available With the aim to find out an enhanced operating-temperature range for photovoltaic device parameters, two types of the photoactive layer were prepared: poly(3-hexylthiophene (P3HT and P3HT+nc-TiO2 (PTC thin films. The enhancement obtained for the photoelectrical conversion efficiency of the composite based OSCs is attributed to the presence of nanoheterojunctions of TiO2/P3HT. For the temperature range of 30–70°C, the decrease of the open-circuit potential was compensated by an increase of the fill factor; and the increase in the short-circuit current resulted in an overall increase of the energy conversion efficiency. At elevated temperatures of 60–80°C the efficiency of the P3HT- and PTC-based cells reached a maximum value of 1.6% and 2.1%, respectively. Over this temperature range the efficiency of P3HT-based OSC decreased strongly to zero, whereas for the PTC cells it maintained a value as large as 1.2% at the temperature range of 110–140°C. The improved thermal stability of the composite-based device was attributed to the lowered thermal expansion coefficient of the nanocomposite photoactive layer.

Chemical Compositions of Stars in the Globular Cluster NGC 3201: Tracers of Multi-Epoch Star Formation

Science.gov (United States)

Simmerer, Jennifer A.; Ivans, I. I.; Filler, D.

2012-01-01

The retrograde halo globular cluster NGC 3201 contains stars of substantially different iron abundance ([Fe/H]), a property that puts it at odds with the vast majority of the Galactic cluster system. Though its unusual orbit prompted speculation that NGC 3201 was the remnant of a captured object, much like the multi-metallicity globular cluster Omega Centauri, NGC 3201 is much less massive than Omega Centauri and all of the other halo globular clusters that have internal metallicity variations. We present the abundances of 21 elements in 24 red giant branch stars in NGC 3201 based on high-resolution (R 40,000), high signal-to-noise (S/N 70) spectra. We find that the detailed abundance pattern of NGC 3201 is unique amongst multi-metallicity halo clusters. Unlike M22, Omega Centauri, and NGC 1851, neither metal-poor nor metal-rich stars show any evidence of s-process enrichment (a product of the advanced evolution of low- and intermediate-mass stars). We find that while Na, O, and Al vary from star to star as is typical in globular clusters, there is no systematic difference between the abundance pattern in the metal-poor cluster stars and that of the metal-rich cluster stars. Furthermore, we find that the metallicity variations in NGC 3201 are independent of the well-known Na-O anticorrelation, which separates it from every other multi-metallicity cluster. In the context of a multi-episode star formation model, this implies that NGC 3201 began life with the [Fe/H] variations we measure now.

Retired A Stars and Their Companions. III. Comparing the Mass-Period Distributions of Planets Around A-Type Stars and Sun-Like Stars

Science.gov (United States)

Bowler, Brendan P.; Johnson, John Asher; Marcy, Geoffrey W.; Henry, Gregory W.; Peek, Kathryn M. G.; Fischer, Debra A.; Clubb, Kelsey I.; Liu, Michael C.; Reffert, Sabine; Schwab, Christian; Lowe, Thomas B.

2010-01-01

We present an analysis of ~5 years of Lick Observatory radial velocity measurements targeting a uniform sample of 31 intermediate-mass (IM) subgiants (1.5 lsim M */M sunlsim 2.0) with the goal of measuring the occurrence rate of Jovian planets around (evolved) A-type stars and comparing the distributions of their orbital and physical characteristics to those of planets around Sun-like stars. We provide updated orbital solutions incorporating new radial velocity measurements for five known planet-hosting stars in our sample; uncertainties in the fitted parameters are assessed using a Markov-Chain Monte Carlo method. The frequency of Jovian planets interior to 3 AU is 26+9 -8%, which is significantly higher than the 5%-10% frequency observed around solar-mass stars. The median detection threshold for our sample includes minimum masses down to {0.2, 0.3, 0.5, 0.6, 1.3} M Jup within {0.1, 0.3, 0.6, 1.0, 3.0} AU. To compare the properties of planets around IM stars to those around solar-mass stars we synthesize a population of planets based on the parametric relationship dN vprop M α P β dlnMdlnP, the observed planet frequency, and the detection limits we derived. We find that the values of α and β for planets around solar-type stars from Cumming et al. fail to reproduce the observed properties of planets in our sample at the 4σ level, even when accounting for the different planet occurrence rates. Thus, the properties of planets around A stars are markedly different than those around Sun-like stars, suggesting that only a small (~50%) increase in stellar mass has a large influence on the formation and orbital evolution of planets. Based on observations obtained at the Lick Observatory, which is operated by the University of California.

Initial results from NuSTAR observations of the Norma arm

DEFF Research Database (Denmark)

Bodaghee, Arash; Tomsick, John A.; Krivonos, Roman

2014-01-01

Results are presented for an initial survey of the Norma Arm gathered with the focusing hard X-ray telescope NuSTAR. The survey covers 0.2 deg2 of sky area in the 3-79 keV range with a minimum and maximum raw depth of 15 ks and 135 ks, respectively. Besides a bright black-hole X-ray binary...

Light-induced EPR study of charge transfer in P3HT/bis-PCBM bulk heterojunctions

Directory of Open Access Journals (Sweden)

Victor I. Krinichnyi

2011-06-01

Full Text Available Radical pairs, polarons and fullerene anion radicals photoinduced by photons with energy of 1.98 – 2.73 eV in bulk heterojunctions formed by poly(3-hexylthiophene (P3HT with bis(1-[3-(methoxycarbonylpropyl]-1-phenyl-[6.6]C62 (bis-PCBM fullerene derivative have been studied by direct light-induced EPR (LEPR method in a wide temperature range. A part of photoinduced polarons are pinned in trap sites which number and depth are governed by an ordering of the polymer/fullerene system and energy of initiating photons. It was shown that dynamics and recombination of mobile polarons and counter fullerene anion radicals are governed by their exchange- and multi-trap assisted diffusion. Relaxation and dynamics parameters of both the charge carriers were determined separately by the steady-state saturation method. These parameters are governed by structure and conformation of the carriers’ microenvironment as well as by the energy of irradiating photons. Longitudinal diffusion of polarons was shown to depend on lattice phonons of crystalline domains embedded into an amorphous polymer matrix. The energy barrier required for polaron interchain hopping is higher than that its intrachain diffusion. Pseudorotation of fullerene derivatives in a polymer matrix was shown to follow the activation Pike model.

Synthesis of naturally-derived macromolecules through simplified electrochemically mediated ATRP

Directory of Open Access Journals (Sweden)

Paweł Chmielarz

2017-11-01

Full Text Available The flavonoid-based macroinitiator was received for the first time by the transesterification reaction of quercetin with 2-bromoisobutyryl bromide. In accordance with the “grafting from” strategy, a naturally-occurring star-like polymer with a polar 3,3',4',5,6-pentahydroxyflavone core and hydrophobic poly(tert-butyl acrylate (PtBA side arms was synthesized via a simplified electrochemically mediated ATRP (seATRP, utilizing only 78 ppm by weight (wt of a catalytic CuII complex. To demonstrate the possibility of temporal control, seATRP was carried out utilizing a multiple-step potential electrolysis. The rate of the polymerizations was well-controlled by applying optimal potential values during preparative electrolysis to prevent the possibility of intermolecular coupling of the growing polymer arms. This appears to be the first report using on-demand seATRP for the synthesis of QC-(PtBA-Br5 pseudo-star polymers. The naturally-derived macromolecules showed narrow MWDs (Đ = 1.08–1.11. 1H NMR spectral results confirm the formation of quercetin-based polymers. These new flavonoid-based polymer materials may find applications as antifouling coatings and drug delivery systems.

Photoconductance of Bulk Heterojunctions with Tunable Nanomorphology Consisting of P3HT and Naphtalene Diimide Siloxane Oligomers

NARCIS (Netherlands)

Grzegorczyk, W.J.; Ganesan, P.; Savenije, T.J.; Bavel, van S.; Loos, J.; Sudhölter, E.J.R.; Siebbeles, L.D.A.; Zuilhof, H.

2009-01-01

The relation between the morphology, optical, and photoconductive properties of thin-film bulk heterojunctions of poly(3-hexylthiophene) (P3HT) with a series of electron-accepting siloxanes with a different number (x = 2, 4, 5) of pendant naphthalene diimide (NDIS) moieties is reported. All NDIS

Regional hyperthermia combined with radiotherapy for locally advanced non-small cell lung cancers. A multi-institutional prospective randomized trial of the International Atomic Energy Agency

International Nuclear Information System (INIS)

Mitsumori, Michihide; Hiraoka, Masahiro; Zeng Zhifan; Oliynychenko, P.; Park, Jeong-Ho; Choi, Ihl-Bohng; Tatsuzaki, Hideo; Tanaka, Yoshiaki

2007-01-01

An International Atomic Energy Agency (IAEA)-sponsored, multi-institutional prospective randomized trial was conducted to clarify whether the combination of hyperthermia and radiotherapy improves the local response rate of locally advanced non-small cell lung cancer (NSCLC) compared with that obtained by radiotherapy alone. Between October 1998 and April 2002, 80 patients with locally advanced NSCLC were randomized to receive either standard radiation therapy alone (RT) or radiation therapy combined with hyperthermia (RT+HT). The primary endpoint was the local response rate. The secondary endpoints were local progression-free survival and overall survival. The median follow-up period was 204 days for all patients and 450 days for surviving patients. There were no significant differences between the two arms with regard to local response rate (P=0.49) or overall survival rate (P=0.868). However, local progression-free survival was significantly better in the RT+HT arm (P=0.036). Toxicity was generally mild and no grade 3 late toxicity was observed in either arm. Although improvement of local progression-free survival was observed in the RT+HT arm, this prospective randomized study failed to show any substantial benefit from the addition of hyperthermia to radiotherapy in the treatment of locally advanced NSCLC. (author)

Synchrotron X-ray scattering characterization of the molecular structures of star polystyrenes with varying numbers of arms.

Science.gov (United States)

Jin, Sangwoo; Higashihara, Tomoya; Jin, Kyeong Sik; Yoon, Jinhwan; Rho, Yecheol; Ahn, Byungcheol; Kim, Jehan; Hirao, Akira; Ree, Moonhor

2010-05-20

We have synthesized well-defined multiarmed star polystyrenes, with 6, 9, 17, 33, and 57 arms, and studied their molecular shapes and structural characteristics in a good solvent (tetrahydrofuran at 25 degrees C) and in a theta (Theta) solvent (cyclohexane at 35 degrees C) by small-angle X-ray scattering (SAXS) using a synchrotron radiation source. Analysis of the SAXS data provided a detailed characterization of the molecular shapes, including the contributions of the blob morphology of the arms, the radius of gyration, the paired distance distribution, the radial electron density distribution, and the Zimm-Stockmayer and Roovers g-factor, for the multiarmed star polystyrenes. In particular, the molecular shapes of the star polystyrenes were found to change from a fuzzy ellipsoid, for the 6-armed polystyrene, to a fuzzy sphere, for the 57-armed polystyrene, with an increasing number of arms. The ellipsoidal character of the star polystyrenes with fewer arms may originate from the extended anisotropically branched architecture at the center of the molecule. The arms of the star polystyrenes were found to be more extended than those of the linear polystyrenes. Furthermore, the degree of chain extension in the arms increased with the number of arms.

Trigonometric parallaxes of star forming regions in the Scutum spiral arm

International Nuclear Information System (INIS)

Sato, M.; Wu, Y. W.; Immer, K.; Zhang, B.; Sanna, A.; Brunthaler, A.; Menten, K. M.; Reid, M. J.; Dame, T. M.

2014-01-01

We report measurements of trigonometric parallaxes for six high-mass star-forming regions in the Scutum spiral arm of the Milky Way as part of the BeSSeL Survey. Combining our measurements with 10 previous measurements from the BeSSeL Survey yields a total sample of 16 sources in the Scutum arm with trigonometric parallaxes in the Galactic longitude range from 5° to 32°. Assuming a logarithmic spiral model, we estimate a pitch angle of 19.°8 ± 3.°1 for the Scutum arm, which is larger than pitch angles reported for other spiral arms. The high pitch angle of the arm may be due to the arm's proximity to the Galactic bar. The Scutum arm sources show an average peculiar motion of 4 km s –1 slower than the Galactic rotation and 8 km s –1 toward the Galactic center. While the direction of this non-circular motion has the same sign as determined for sources in other spiral arms, the motion toward the Galactic center is greater for the Scutum arm sources.

Structural Studies of Three-Arm Star Block Copolymers Exposed to Extreme Stretch Suggests a Persistent Polymer Tube

Science.gov (United States)

Mortensen, Kell; Borger, Anine L.; Kirkensgaard, Jacob J. K.; Garvey, Christopher J.; Almdal, Kristoffer; Dorokhin, Andriy; Huang, Qian; Hassager, Ole

2018-05-01

We present structural small-angle neutron scattering studies of a three-armed polystyrene star polymer with short deuterated segments at the end of each arm. We show that the form factor of the three-armed star molecules in the relaxed state agrees with that of the random phase approximation of Gaussian chains. Upon exposure to large extensional flow conditions, the star polymers change conformation resulting in a highly stretched structure that mimics a fully extended three-armed tube model. All three arms are parallel to the flow, one arm being either in positive or negative stretching direction, while the two other arms are oriented parallel, right next to each other in the direction opposite to the first arm.

5HT-1A receptors and anxiety-like behaviours: studies in rats with constitutionally upregulated/downregulated serotonin transporter.

Science.gov (United States)

Bordukalo-Niksic, Tatjana; Mokrovic, Gordana; Stefulj, Jasminka; Zivin, Marko; Jernej, Branimir; Cicin-Sain, Lipa

2010-12-01

Altered activity of brain serotonergic (5HT) system has been implicated in a wide range of behaviours and behavioural disorders, including anxiety. Functioning of 5HT-1A receptor has been suggested as a modulator of emotional balance in both, normal and pathological forms of anxiety. Here, we studied serotonergic modulation of anxiety-like behaviour using a genetic rat model with constitutional differences in 5HT homeostasis, named Wistar-Zagreb 5HT (WZ-5HT) rats. The model, consisting of high-5HT and low-5HT sublines, was developed by selective breeding of animals for extreme activities of peripheral (platelet) 5HT transporter, but selection process had affected also central 5HT homeostasis, as evidenced from neurochemical and behavioural studies. Anxiety-like behaviour in WZ-5HT rats was evaluated by two commonly used paradigms: open field and elevated-plus maze. The involvement of 5HT-1A receptors in behavioural response was assessed by measuring mRNA expression in cell bodies (raphe nuclei) and projection regions (frontal cortex, hippocampus) by use of RT-PCR and in situ hybridization, and by measuring functionality of cortical 5HT-1A receptors by use of [(3)H]8-OH-DPAT radioligand binding. Animals from the high-5HT subline exhibit increased anxiety-like behaviour and decreased exploratory activity when exposed to novel environment. No measurable differences in constitutional (baseline) functionality or expression of 5HT-1A receptors between sublines were found. The results support contribution of increased serotonergic functioning to the anxiety-like behaviour. They also validate the high-5HT subline of WZ-5HT rats as a potential model to study mechanisms of anxiety, especially of its nonpathological form, while the low-5HT subline may be useful to model sensation seeking phenotype. Copyright (c) 2010 Elsevier B.V. All rights reserved.

A soluble star-shaped silsesquioxane-cored polymer-towards novel stabilization of pH-dependent high internal phase emulsions.

Science.gov (United States)

Xing, Yuxiu; Peng, Jun; Xu, Kai; Gao, Shuxi; Gui, Xuefeng; Liang, Shengyuan; Sun, Longfeng; Chen, Mingcai

2017-08-30

A well-defined pH-responsive star-shaped polymer containing poly(N,N-dimethylaminoethyl methacrylate) (PDMA) arms and a cage-like methacryloxypropyl silsesquioxane (CMSQ-T 10 ) core was used as an interfacial stabilizer for emulsions consisting of m-xylene and water. We explored the properties of the CMSQ/PDMA star-shaped polymer using the characteristic results of nuclear magnetic resonance (NMR) spectroscopy, size exclusion chromatography (SEC), dynamic light scattering (DLS), and zeta potential and conductivity measurements. The interfacial tension results showed that the CMSQ/PDMA star-shaped polymer reduced the interfacial tension between water and oil in a pH-dependent manner. Gelled high internal phase emulsions (HIPEs) including o/w and w/o types were formed in the pH ranges of 1.2-5.8 and 9.1-12.3 with the CMSQ/PDMA star-shaped polymer as a stabilizer, when the oil fractions were 80-90 vol% and 10-20 vol%, respectively. The soluble star-shaped polymer aggregated spontaneously to form a microgel that adsorbed to the two immiscible phases. Images of the fluorescently labeled polymers demonstrated that there was a star-shaped polymer in the continuous phase, and the non-Pickering stabilization based on the percolating network of the star-shaped polymer also contributed to the stabilization of the HIPE. This pH-dependent HIPE was prepared with a novel stabilization mechanism consisting of microgel adsorption and non-Pickering stabilization. Moreover, the preparation of HIPEs provided the possibility of their application in porous materials and responsive materials.

5-HT loss in rat brain following 3,4-methylenedioxymethamphetamine (MDMA), p-chloroamphetamine and fenfluramine administration and effects of chlormethiazole and dizocilpine.

Science.gov (United States)

Colado, M I; Murray, T K; Green, A R

1993-03-01

1. The present study has investigated whether the neurotoxic effects of the relatively selective 5-hydroxytryptamine (5-HT) neurotoxins, 3,4-methylenedioxymethamphetamine (MDMA or 'Ecstasy'), p-chloroamphetamine (PCA) and fenfluramine on hippocampal and cortical 5-HT terminals in rat brain could be prevented by administration of either chlormethiazole or dizocilpine. 2. Administration of MDMA (20 mg kg-1, i.p.) resulted in an approximate 30% loss of cortical and hippocampal 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) content 4 days later. Injection of chlormethiazole (50 mg kg-1) 5 min before and 55 min after the MDMA provided complete protection in both regions, while dizocilpine (1 mg kg-1, i.p.) protected only the hippocampus. 3. Administration of a single dose of chlormethiazole (100 mg kg-1) 20 min after the MDMA also provided complete protection to the hippocampus but not the cortex. This regime also attenuated the sustained hyperthermia (approx +2.5 degrees C) induced by the MDMA injection. 4. Injection of PCA (5 mg kg-1, i.p.) resulted in a 70% loss of 5-HT and 5-HIAA content in hippocampus and cortex 4 days later. Injection of chlormethiazole (100 mg kg-1, i.p.) or dizocilpine (1 mg kg-1, i.p.) 5 min before and 55 min after the PCA failed to protect against the neurotoxicity, nor was protection afforded by chlormethiazole when a lower dose of PCA (2.5 mg kg-1, i.p.) was given which produced only a 30% loss of 5-HT content. Chlormethiazole did prevent the hyperthermia induced by PCA (5 mg kg-1), while the lower dose of PCA (2.5 mg kg-1) did not produce a change in body temperature.5. Neither chlormethiazole nor dizocilpine prevented the neurotoxic loss of hippocampal or cortical 5-HT neurones measured 4 days following administration of fenfluramine (25 mg kg-1, i.p.).6. In general, chlormethiazole and dizocilpine were effective antagonists of the 5-HT-mediated behaviours of head weaving and forepaw treading which appeared following injection of all three

Core Cross-linked Star Polymers for Temperature/pH Controlled Delivery of 5-Fluorouracil

Directory of Open Access Journals (Sweden)

Elizabeth Sánchez-Bustos

2016-01-01

Full Text Available RAFT polymerization with cross-linking was used to prepare core cross-linked star polymers bearing temperature sensitive arms. The arms consisted of a diblock copolymer containing N-isopropylacrylamide (NIPAAm and 4-methacryloyloxy benzoic acid (4MBA in the temperature sensitive block and poly(hexyl acrylate forming the second hydrophobic block, while ethyleneglycol dimethacrylate was used to form the core. The acid comonomer provides pH sensitivity to the arms and also increases the transition temperature of polyNIPAAm to values in the range of 40 to 46°C. Light scattering and atomic force microscopy studies suggest that loose core star polymers were obtained. The star polymers were loaded with 5-fluorouracil (5-FU, an anticancer agent, in values of up to 30 w/w%. In vitro release experiments were performed at different temperatures and pH values, as well as with heating and cooling temperature cycles. Faster drug release was obtained at 42°C or pH 6, compared to normal physiological conditions (37°C, pH 7.4. The drug carriers prepared acted as nanopumps changing the release kinetics of 5-FU when temperatures cycles were applied, in contrast with release rates at a constant temperature. The prepared core cross-linked star polymers represent advanced drug delivery vehicles optimized for 5-FU with potential application in cancer treatment.

Hybrid solar cells with outstanding short-circuit currents based on a room temperature soft-chemical strategy: the case of P3HT:Ag2S.

Science.gov (United States)

Lei, Yan; Jia, Huimin; He, Weiwei; Zhang, Yange; Mi, Liwei; Hou, Hongwei; Zhu, Guangshan; Zheng, Zhi

2012-10-24

P3HT:Ag(2)S hybrid solar cells with broad absorption from the UV to NIR band were directly fabricated on ITO glass by using a room temperature, low energy consumption, and low-cost soft-chemical strategy. The resulting Ag(2)S nanosheet arrays facilitate the construction of a perfect percolation structure with organic P3HT to form ordered bulk heterojunctions (BHJ); without interface modification, the assembled P3HT:Ag(2)S device exhibits outstanding short-circuit current densities (J(sc)) around 20 mA cm(-2). At the current stage, the optimized device exhibited a power conversion efficiency of 2.04%.

RETIRED A STARS AND THEIR COMPANIONS. III. COMPARING THE MASS-PERIOD DISTRIBUTIONS OF PLANETS AROUND A-TYPE STARS AND SUN-LIKE STARS

International Nuclear Information System (INIS)

Bowler, Brendan P.; Johnson, John Asher; Liu, Michael C.; Marcy, Geoffrey W.; Peek, Kathryn M. G.; Henry, Gregory W.; Fischer, Debra A.; Clubb, Kelsey I.; Reffert, Sabine; Schwab, Christian; Lowe, Thomas B.

2010-01-01

We present an analysis of ∼5 years of Lick Observatory radial velocity measurements targeting a uniform sample of 31 intermediate-mass (IM) subgiants (1.5 ∼ * /M sun ∼ +9 -8 %, which is significantly higher than the 5%-10% frequency observed around solar-mass stars. The median detection threshold for our sample includes minimum masses down to {0.2, 0.3, 0.5, 0.6, 1.3} M Jup within {0.1, 0.3, 0.6, 1.0, 3.0} AU. To compare the properties of planets around IM stars to those around solar-mass stars we synthesize a population of planets based on the parametric relationship dN ∝ M α P β dlnMdlnP, the observed planet frequency, and the detection limits we derived. We find that the values of α and β for planets around solar-type stars from Cumming et al. fail to reproduce the observed properties of planets in our sample at the 4σ level, even when accounting for the different planet occurrence rates. Thus, the properties of planets around A stars are markedly different than those around Sun-like stars, suggesting that only a small (∼50%) increase in stellar mass has a large influence on the formation and orbital evolution of planets.

Structural studies of three-arm star block copolymers exposed to extreme stretch suggests persistent polymer tube

DEFF Research Database (Denmark)

Garvey, Christopher J.; Almdal, Kristoffer; Dorokhin, Andriy

2018-01-01

We present structural SANS-studies of a three-armed polystyrene star polymer with short deuterated segments at the end of each arm. We show that the form factor of the three-armed star molecules in the relaxed state agrees with that of the random phase approximation of Gaussian chains. Upon...

Arm retraction dynamics of entangled star polymers: A forward flux sampling method study

Science.gov (United States)

Zhu, Jian; Likhtman, Alexei E.; Wang, Zuowei

2017-07-01

The study of dynamics and rheology of well-entangled branched polymers remains a challenge for computer simulations due to the exponentially growing terminal relaxation times of these polymers with increasing molecular weights. We present an efficient simulation algorithm for studying the arm retraction dynamics of entangled star polymers by combining the coarse-grained slip-spring (SS) model with the forward flux sampling (FFS) method. This algorithm is first applied to simulate symmetric star polymers in the absence of constraint release (CR). The reaction coordinate for the FFS method is determined by finding good agreement of the simulation results on the terminal relaxation times of mildly entangled stars with those obtained from direct shooting SS model simulations with the relative difference between them less than 5%. The FFS simulations are then carried out for strongly entangled stars with arm lengths up to 16 entanglements that are far beyond the accessibility of brute force simulations in the non-CR condition. Apart from the terminal relaxation times, the same method can also be applied to generate the relaxation spectra of all entanglements along the arms which are desired for the development of quantitative theories of entangled branched polymers. Furthermore, we propose a numerical route to construct the experimentally measurable relaxation correlation functions by effectively linking the data stored at each interface during the FFS runs. The obtained star arm end-to-end vector relaxation functions Φ (t ) and the stress relaxation function G(t) are found to be in reasonably good agreement with standard SS simulation results in the terminal regime. Finally, we demonstrate that this simulation method can be conveniently extended to study the arm-retraction problem in entangled star polymer melts with CR by modifying the definition of the reaction coordinate, while the computational efficiency will depend on the particular slip-spring or slip

Structural and morphological changes in P3HT thin film transistors applying an electric field

Energy Technology Data Exchange (ETDEWEB)

Tiwari, Deepak Kumar; Grigorian, Souren; Pietsch, Ullrich [University of Siegen (Germany); Flesch, Heinz; Resel, Roland [University of Siegen (Germany); Graz University of Technology (Austria)

2010-07-01

We report on electric field dependent crystalline structure and morphological changes of drop casting and spin coated poly(3-hexylthiophene) (P3HT) thin films. In order to probe the morphological changes induced by an applied electric field the samples were covered with thin source/drain electrodes separated by a small channel of 2 mm width. A series of x-ray reflectivity, X-ray grazing incidence out-of-plane and in-plane scans have been performed as function of the applied electric voltage. The (100) peak shows a decrease in intensity with increase of the applied electric field. This might be caused by Joule heating and the creation of current induced defects in the P3HT film. On other hand the (020) peak intensity shows much stronger changes with applied field. Considering the *-* stacking direction the measured effect can be directly related to a change in the electric transport. The observed changes in structure are reversible and the current-voltage cycle can be repeated several times. For X-ray reflectivity major changes have been found close to critical angle of total external reflection indicating the film becomes less dense and increases in surface roughness with increase of the voltage. This change in surface behaviour could be confirmed by in-situ AFM measurements.

Admittance Control of a Multi-Finger Arm Based on Manipulability of Fingers

Directory of Open Access Journals (Sweden)

Jian Huang

2011-09-01

Full Text Available In the previous studies, admittance control and impedance control for a finger-arm robot using the manipulability of the finger were studied and methods of realizing the controls have been proposed. In this study, two 3-DOF fingers are attached to the end-effector of a 6-DOF arm to configure a multi-finger arm robot. Based on the previous methods, the authors have proposed an admittance control for a multi-finger arm robot using the manipulability of the fingers in this study. Algorithms of the averaging method and the mini-max method were introduced to establish a manipulability criterion of the two fingers in order to generate a cooperative movement of the arm. Comparison of the admittance controls combined with the top search method and local optimization method for the multi-finger arm robot was made and features of the control methods were also discussed. The stiffness control and damping control were experimentally evaluated to demonstrate the effectiveness of the proposed methods.

Gravitational Waves from Stellar Black Hole Binaries and the Impact on Nearby Sun-like Stars

Energy Technology Data Exchange (ETDEWEB)

Lopes, Ilídio [Centro Multidisciplinar de Astrofísica, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Silk, Joseph, E-mail: ilidio.lopes@tecnico.ulisboa.pt, E-mail: silk@astro.ox.ac.uk [Institut d’Astrophysique de Paris, UMR 7095 CNRS, Université Pierre et Marie Curie, 98 bis Boulevard Arago, Paris F-75014 (France)

2017-07-20

We investigate the impact of resonant gravitational waves on quadrupole acoustic modes of Sun-like stars located nearby stellar black hole binary systems (such as GW150914 and GW151226). We find that the stimulation of the low-overtone modes by gravitational radiation can lead to sizeable photometric amplitude variations, much larger than the predictions for amplitudes driven by turbulent convection, which in turn are consistent with the photometric amplitudes observed in most Sun-like stars. For accurate stellar evolution models, using up-to-date stellar physics, we predict photometric amplitude variations of 1–10{sup 3} ppm for a solar mass star located at a distance between 1 au and 10 au from the black hole binary and belonging to the same multi-star system. The observation of such a phenomenon will be within the reach of the Plato mission because the telescope will observe several portions of the Milky Way, many of which are regions of high stellar density with a substantial mixed population of Sun-like stars and black hole binaries.

Star Formation Activity Beyond the Outer Arm. I. WISE -selected Candidate Star-forming Regions

Energy Technology Data Exchange (ETDEWEB)

Izumi, Natsuko; Yasui, Chikako; Saito, Masao [National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo 181-8588 (Japan); Kobayashi, Naoto; Hamano, Satoshi, E-mail: natsuko.izumi@nao.ac.jp [Laboratory of Infrared High-resolution spectroscopy (LIH), Koyama Astronomical Observatory, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555 (Japan)

2017-10-01

The outer Galaxy beyond the Outer Arm provides a good opportunity to study star formation in an environment significantly different from that in the solar neighborhood. However, star-forming regions in the outer Galaxy have never been comprehensively studied or cataloged because of the difficulties in detecting them at such large distances. We studied 33 known young star-forming regions associated with 13 molecular clouds at R {sub G} ≥ 13.5 kpc in the outer Galaxy with data from the Wide-field Infrared Survey Explorer ( WISE ) mid-infrared all-sky survey. From their color distribution, we developed a simple identification criterion of star-forming regions in the outer Galaxy with the WISE color. We applied the criterion to all the WISE sources in the molecular clouds in the outer Galaxy at R {sub G} ≥ 13.5 kpc detected with the Five College Radio Astronomy Observatory (FCRAO) {sup 12}CO survey of the outer Galaxy, of which the survey region is 102.°49 ≤  l  ≤ 141.°54, −3.°03 ≤  b  ≤ 5.°41, and successfully identified 711 new candidate star-forming regions in 240 molecular clouds. The large number of samples enables us to perform the statistical study of star formation properties in the outer Galaxy for the first time. This study is crucial to investigate the fundamental star formation properties, including star formation rate, star formation efficiency, and initial mass function, in a primordial environment such as the early phase of the Galaxy formation.

The Effect of Ageing on Exciton Dynamics, Charge Separation, and Recombination in P3HT/PCBM Photovoltaic Blends

NARCIS (Netherlands)

Deschler, Felix; Sio, Antonietta De; von Hauff, Elizabeth; Kutka, Peter; Sauermann, Tobias; Egelhaaf, Hans-j; Hauch, Jens; Da Como, Enrico

2012-01-01

A study of how light-induced degradation influences the fundamental photophysical processes in the active layer of poly(3-hexylthiophene)/[6,6]-phenyl C61-butyric acid methyl ester (P3HT/PCBM) solar cells is presented. Non-encapsulated samples are systematically aged by exposure to AM 1.5

A New All-Solid-State Hyperbranched Star Polymer Electrolyte for Lithium Ion Batteries: Synthesis and Electrochemical Properties

International Nuclear Information System (INIS)

Wang, Ailian; Xu, Hao; Zhou, Qian; Liu, Xu; Li, Zhengyao; Gao, Rui; Wu, Na; Guo, Yuguo; Li, Huayi; Zhang, Liaoyun

2016-01-01

Highlights: • A new hyperbranched multi-arm star polymer was successfully synthesized. • The star polymer electrolyte has good thermal stability and forming-film property. • The ion conductivity electrolyte can reach 8.3 × 10"−"5 S cm"−"1 at room temperature. • The star polymer electrolyte has wide electrochemical windows of 4.7 V. - Abstract: A new hyperbranched multi-arm star polymer with hyperbranched polystyrene (HBPS) as core and polymethyl methacrylate-block-poly(ethylene glycol) methyl ether methacrylate(PMMA-b-PPEGMA) as arms was firstly synthesized by atom transfer radical polymerization. The obtained hyperbranched multi-arm star polymer (HBPS-(PMMA-b-PPEGMA)_x) exhibited good thermal stability with a thermal decomposition temperature of 372 °C. The transparent, free-standing, flexible polymer electrolyte film of the blending of HBPS-(PMMA-b-PPEGMA)_x and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) was successfully fabricated by a solution casting method. The ionic conductivity of the hyperbranched star polymer electrolyte with a molar ratio of [EO]/[Li] of 30 could reach 8.3 × 10"−"5 S cm"−"1 at 30 °C (with the content of PPEGMA of 83.7%), and 2.0 × 10"−"4 S cm"−"1 at 80 °C (with the content of PPEGMA of 51.6%). The effect of the concentration of lithium salts on ionic conductivity was also investigated. The obtained all-solid-state polymer electrolyte possessed a wide electrochemical stability window of 4.7 V (vs. Li"+/Li), and a lithium-ion transference number (t_L_i"+) up to 0.31. The interfacial impedance of the fabricated LiÔöépolymer electrolyteÔöéLi symmetric cell based on hyperbranched star multi-arm polymer electrolyte exhibited good interfacial compatibility between all-solid-state polymer electrolyte and electrodes. The excellent properties of the hyperbranched star polymer electrolyte made it attractive as solid-state polymer electrolyte for lithium-ion batteries.

Synthesis of Well-Defined Three-Arm Star-Branched Polystyrene through Arm-First Coupling Approach by Atom Transfer Radical Polymerization

Directory of Open Access Journals (Sweden)

Syed Shahabuddin

2015-01-01

Full Text Available Here we describe a simple route to synthesize three-arm star-branched polystyrene. Atom transfer radical polymerization technique has been utilized to yield branched polystyrene involving Williamson coupling strategy. Initially a linear polymeric chain of predetermined molecular weight has been synthesized which is further end-functionalized into a primary alkyl bromide moiety, a prime requisition for Williamson reaction. The end-functionalized polymer is then coupled using 1,1,1-tris(4-hydroxyphenylethane, a trifunctional core molecule, to give well-defined triple-arm star-branched polystyrene.

Enhanced performance of P3HT/(PCBM:ZnO:TiO{sub 2}) blend based hybrid organic solar cells

Energy Technology Data Exchange (ETDEWEB)

Ikram, M., E-mail: mianraj.1981@gmail.com [Solar Application Lab, Department of Physics, Government College University Lahore, 54000 Pakistan (Pakistan); Murray, R. [Department of Physics and Astronomy, University of Delaware, Delaware 19716 (United States); Imran, M. [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 29 Zhongguancun East Road, Haidian District, Beijing 100190 (China); Ali, S. [Solar Application Lab, Department of Physics, Government College University Lahore, 54000 Pakistan (Pakistan); Shah, S.Ismat [Department of Materials Science and Engineering, University of Delaware, Delaware 19716 (United States); Department of Physics and Astronomy, University of Delaware, Delaware 19716 (United States)

2016-03-15

Highlights: • We fabricated hybrid bulk heterojunction organic solar cells. • TiO{sub 2} and ZnO nanoparticles replace PCBM with fixed amount of P3HT in active layer • PCE was significantly improved by the introduction of TiO{sub 2} and ZnO. • A possible route toward low-cost OPV. • To the best of my knowledge, this work is the first time going to report. - Abstract: Quaternary blend hybrid organic solar cells enjoy both an increased light absorption range and an easy method to fabricate because of the simple structure. In this study effects of mixing inorganic metal oxides (ZnO and TiO{sub 2}) nanoparticles to the active layer of organic photovoltaics devices were investigated. The active layer primarily consists of various ratios of electron donor poly (3-hexylthiophene) (P3HT) and an electron acceptor [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) together with nanostructured ZnO and TiO{sub 2} dispersed in chlorobenzene (CB) and 1,2-dichlorobenzene (DCB). The ratio of PCBM to nanoparticles was varied keeping the ratio of P3HT to acceptor material constant. Mixing of nanoparticle plays a significant role in the resulting power conversion efficiency (PCE) of the devices. An increased PCE for ZnO/TiO{sub 2} doped devices can be attributed to increased absorption in the visible region and enhanced charge collection due to the percolation networks formed by metal oxides nanoparticles.

Prevalence of Earth-size planets orbiting Sun-like stars.

Science.gov (United States)

Petigura, Erik A; Howard, Andrew W; Marcy, Geoffrey W

2013-11-26

Determining whether Earth-like planets are common or rare looms as a touchstone in the question of life in the universe. We searched for Earth-size planets that cross in front of their host stars by examining the brightness measurements of 42,000 stars from National Aeronautics and Space Administration's Kepler mission. We found 603 planets, including 10 that are Earth size ( ) and receive comparable levels of stellar energy to that of Earth (1 - 2 R[Symbol: see text] ). We account for Kepler's imperfect detectability of such planets by injecting synthetic planet-caused dimmings into the Kepler brightness measurements and recording the fraction detected. We find that 11 ± 4% of Sun-like stars harbor an Earth-size planet receiving between one and four times the stellar intensity as Earth. We also find that the occurrence of Earth-size planets is constant with increasing orbital period (P), within equal intervals of logP up to ~200 d. Extrapolating, one finds 5.7(-2.2)(+1.7)% of Sun-like stars harbor an Earth-size planet with orbital periods of 200-400 d.

ITO electrode/photoactive layer interface engineering for efficient inverted polymer solar cells based on P3HT and PCBM using a solution-processed titanium chelate

International Nuclear Information System (INIS)

Zhang Wenqing; Zheng Hua; Tan Zhan'ao; Qian Deping; Li Liangjie; Xu Qi; Li Shusheng; Li Yongfang

2012-01-01

We report efficient inverted polymer solar cells (PSCs) based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) using alcohol-soluble titanium (diisopropoxide) bis (2,4-pentanedionate) (TIPD) as an electron selective layer between the indium tin oxide (ITO) electrode and the photoactive layer. The thermally annealed TIPD layer is highly transparent in the visible range and shows effective electron collection ability. By optimizing the electron-collecting layer, the photoactive layer and the hole-collecting layer, the power conversion efficiency (PCE) of the inverted device with the structure ITO/TIPD/P3HT : PCBM/MoO 3 /Ag reaches 4.10% under the illumination of AM1.5G, 100 mW cm -2 , which is among the highest values for inverted PSCs based on P3HT : PCBM. The PCE of the inverted device is improved in comparison with the conventional device (3.77%) under the same experimental conditions. (paper)

Optical properties of P3HT:tributylphosphine oxide-capped CdSe nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Benchaabane, A. [Faculte des Sciences d' Amiens, Laboratoire de Physique de la Matiere Condensee, Amiens (France); Universite Tunis El-Manar, Laboratoire de Materiaux avances et phenomenes quantiques, Faculte des Sciences de Tunis El Manar, Tunis (Tunisia); Universite Arabe des Sciences, Ecole Superieure d' Ingenieurs et des Etudes Technologiques, Tunis (Tunisia); Ben Hamed, Z.; Kouki, F.; Bouchriha, H. [Universite Tunis El-Manar, Laboratoire de Materiaux avances et phenomenes quantiques, Faculte des Sciences de Tunis El Manar, Tunis (Tunisia); Lahmar, A.; Zellama, K.; Zeinert, A. [Faculte des Sciences d' Amiens, Laboratoire de Physique de la Matiere Condensee, Amiens (France); Sanhoury, M.A. [Laboratoire de Chimie Organique Structurale, Synthese et Etudes Physicochimiques, Tunis (Tunisia)

2016-08-15

The optical properties of nanocomposite layers prepared by incorporation of tributylphosphine oxide (TBPO)-capped CdSe nanocrystals (NCs) in a P3HT polymer matrix are studied using different nanocrystal concentrations. Reflection spectra analyzed through Kim oscillator model lead to the determination of optical constants such as refractive index n, extinction coefficient k, dielectric permittivity ε and absorption coefficient α. Using the common Cauchy, Drude-Lorentz, Tauc and single-effective-oscillator theoretical models, we have determined the values of static refractive index n{sub s} and permittivity ε{sub s}, plasma frequency ω{sub p}, carrier density N, optical band gap E{sub g} and oscillator and dispersion energies E{sub 0} and E{sub d}, respectively. It is found that TBPO-capped CdSe NCs concentration affects the optoelectronic parameters of the nanocomposite thin films. Moreover, the disorder of this hybrid system is also studied by the determination of Urbach energy, which increases with TBPO-capped CdSe concentration. (orig.)

FARADAY ROTATION IN THE TAIL OF THE PLANETARY NEBULA DeHt 5

International Nuclear Information System (INIS)

Ransom, R. R.; Kothes, R.; Wolleben, M.; Landecker, T. L.

2010-01-01

We present 1420 MHz polarization images of a 5 0 x 5 0 region around the planetary nebula (PN) DeHt 5. The images reveal narrow Faraday-rotation structures on the visible disk of DeHt 5, as well as two wider, tail-like, structures 'behind' DeHt 5. Though DeHt 5 is an old PN known to be interacting with the interstellar medium (ISM), a tail has not previously been identified for this object. The innermost tail is ∼3 pc long and runs away from the northeast edge of DeHt 5 in a direction roughly opposite that of the sky-projected space velocity of the white dwarf central star, WD 2218+706. We believe this tail to be the signature of ionized material ram-pressure stripped and deposited downstream during a >74,000 yr interaction between DeHt 5 and the ISM. We estimate the rotation measure (RM) through the inner tail to be -15 ± 5 rad m -2 , and, using a realistic estimate for the line-of-sight component of the ISM magnetic field around DeHt 5, derive an electron density in the inner tail of n e = 3.6 ± 1.8 cm -3 . Assuming the material is fully ionized, we estimate a total mass in the inner tail of 0.68 ± 0.33 M sun and predict that 0.49 ± 0.33 M sun was added during the PN-ISM interaction. The outermost tail consists of a series of three roughly circular components, which have a collective length of ∼11.0 pc. This tail is less conspicuous than the inner tail and may be the signature of the earlier interaction between the WD 2218+706 asymptotic giant branch (AGB) progenitor and the ISM. The results for the inner and outer tails are consistent with hydrodynamic simulations and may have implications for the PN missing-mass problem as well as for models which describe the impact of the deaths of intermediate-mass stars on the ISM.

A deep near-infrared spectroscopic survey of the Scutum-Crux arm for Wolf-Rayet stars

Science.gov (United States)

Rosslowe, C. K.; Crowther, Paul A.

2018-01-01

We present a New Technology Telescope/Son-of-Isaac spectroscopic survey of infrared selected Wolf-Rayet (WR) candidates in the Scutum-Crux spiral arm (298° ≤ l ≤ 340°, |b| ≤ 0.5°. We obtained near-IR spectra of 127 candidates, revealing 17 WR stars - a ∼13 per cent success rate - of which 16 are newly identified here. The majority of the new WR stars are classified as narrow-lined WN5-7 stars, with two broad-lined WN4-6 stars and three WC6-8 stars. The new stars, with distances estimated from previous absolute magnitude calibrations, have no obvious association with the Scutum-Crux arm. Refined near-infrared (YHJK) classification criteria based on over a hundred Galactic and Magellanic Cloud WR stars, providing diagnostics for hydrogen in WN stars, plus the identification of WO stars and intermediate WN/C stars. Finally, we find that only a quarter of WR stars in the survey region are associated with star clusters and/or H II regions, with similar statistics found for luminous blue variables (LBVs) in the Milky Way. The relative isolation of evolved massive stars is discussed, together with the significance of the co-location of LBVs and WR stars in young star clusters.

Evolution of Gas Across Spiral Arms in the Whirlpool Galaxy

Science.gov (United States)

Louie, Melissa Nicole

To investigate the dynamic evolution of gas across spiral arms, we conducted a detailed study of the gas and star formation along the spiral arms in the Whirlpool Galaxy, M51. This nearby, face-on spiral galaxy provides a unique laboratory to study the relationship between gas dynamics and star formation. The textbook picture of interstellar medium (ISM) evolution is rapidly changing. Molecular gas was once believed to form along spiral arms from the diffuse atomic gas in the inter-arm regions. Star formation occurs within giant molecular clouds during spiral arm passage. Lastly, the molecular gas is photo-dissociated back into atomic gas by massive stars on the downstream side of the spiral arm. Recent evidence, however, is revealing a new picture of the interstellar medium and the process of star formation. We seek development of a new picture by studying the development and evolution of molecular gas and the role of large scale galactic dynamics in organizing the interstellar medium. This thesis begins by presenting work measuring the geometrical offsets between interstellar gas and recent star formation. Interstellar gas is traced by atomic hydrogen and carbon monoxide (CO). Star formation is traced by ionized hydrogen recombination lines and infrared emission from dust warmed by young bright stars. Measuring these offsets can help determine the underlying large scale galactic dynamics. Along the spiral arms in M51, offsets between CO and the star formation tracers suggest that gas is flowing through the spiral arms, but the offsets do not show the expected signature of a single pattern speed and imply a more complicated pattern. This thesis also examines the intermediate stages of gas evolution, by studying a denser component of the ISM closer to which stars will form. Only a small percent of the bulk molecular gas will become dense enough to form stars. HCN and HCO+ probe densities ˜104 cm-3, where as the bulk gas is 500 cm-3. This thesis looks at HCN and

A Molecular-Scale Understanding of Cohesion and Fracture in P3HT:Fullerene Blends

KAUST Repository

Tummala, Naga Rajesh

2015-04-21

Quantifying cohesion and understanding fracture phenomena in thin-film electronic devices are necessary for improved materials design and processing criteria. For organic photovoltaics (OPVs), the cohesion of the photoactive layer portends its mechanical flexibility, reliability, and lifetime. Here, the molecular mechanism for the initiation of cohesive failure in bulk heterojunction (BHJ) OPV active layers derived from the semiconducting polymer poly-(3-hexylthiophene) [P3HT] and two mono-substituted fullerenes is examined experimentally and through molecular-dynamics simulations. The results detail how, under identical conditions, cohesion significantly changes due to minor variations in the fullerene adduct functionality, an important materials consideration that needs to be taken into account across fields where soluble fullerene derivatives are used.

Effects of current stress and thermal storage on polymeric heterojunction P3HT:PCBM solar cell

DEFF Research Database (Denmark)

Rizzo, Antonio; Cester, Andrea; Torto, Lorenzo

2016-01-01

We subjected P3HT:PCBM solar cells to electrical constant current stress and thermal storage. We employed the impedance spectroscopy technique combined to conventional DC measurements for device characterization during all stresses. We identified and separated different contributions affecting...... the open circuit voltage and short circuit current. Several mechanisms are behind these changes during the stresses; in particular, we underlined the exciton recombination rate and the variation of the built-in voltage....

Ebselen has lithium-like effects on central 5-HT2A receptor function.

Science.gov (United States)

Antoniadou, I; Kouskou, M; Arsiwala, T; Singh, N; Vasudevan, S R; Fowler, T; Cadirci, E; Churchill, G C; Sharp, T

2018-02-27

Lithium's antidepressant action may be mediated by inhibition of inositol monophosphatase (IMPase), a key enzyme in G q protein coupled receptor signalling. Recently, the antioxidant agent ebselen was identified as an IMPase inhibitor. Here we investigated both ebselen and lithium in models of the 5-HT 2A receptor, a G q protein coupled receptor implicated in lithium's actions. 5-HT 2A receptor function was modelled in mice by measuring the behavioural (head-twitches) and cortical immediate early gene (IEG; Arc, c-fos and Erg2 mRNA) responses to 5-HT 2A receptor agonist administration. Ebselen and lithium were administered either acutely or chronically prior to assessment of 5-HT 2A receptor function. Given the SSRI augmenting action of lithium and 5-HT 2A antagonists, ebselen was also tested for this action by co-administration with the SSRI citalopram in microdialysis (extracellular 5-HT) experiments. Acute and repeated administration of ebselen inhibited behavioural and IEG responses to the 5-HT 2A receptor agonist DOI. Repeated lithium also inhibited DOI-evoked behavioural and IEG responses. In comparison, a selective IMPase inhibitor (L-690,330) attenuated the behavioural response to DOI whereas glycogen synthase kinase inhibitor (AR-A014418) did not. Finally, ebselen increased regional brain 5-HT synthesis and enhanced the increase in extracellular 5-HT induced by citalopram. The current data demonstrate lithium-mimetic effects of ebselen in different experimental models of 5-HT 2A receptor function, likely mediated by IMPase inhibition. This evidence of lithium-like neuropharmacological effects of ebselen adds further support for the clinical testing of ebselen in mood disorder, including as an antidepressant augmenting agent. This article is protected by copyright. All rights reserved.

Ultra-low p-doping of poly(3-hexylthiophene) and its impact on polymer aggregation and photovoltaic performance

KAUST Repository

Said, Marcel M.

2016-04-25

Poly(3-hexylthiophene) (P3HT) films and P3HT / fullerene photovoltaic cells have been p-doped with very low levels (< 1 wt. %) of molybdenum tris[1-(trifluoromethylcarbonyl)- 2-(trifluoromethyl)-ethane-1,2-dithiolene]. The dopants are inhomogenously distributed within doped P3HT films, both laterally and as a function of depth, and appear to aggregate in some instances. Doping also results in subtle changes in the local and long range order of the P3HT film. These effects likely contribute to the complexity of the observed evolutions in conductivity, mobility and work function with doping levels. They also negatively affect the open-circuit voltage and fill factor of solar cells in unexpected ways, indicating that dopant aggregation and non-uniform distribution can harm device performance.

Ultra-low p-doping of poly(3-hexylthiophene) and its impact on polymer aggregation and photovoltaic performance

KAUST Repository

Said, Marcel M.; Zhang, Yadong; Dasari, Raghunath R.; Anjum, Dalaver H.; Munir, Rahim; Hu, Hanlin; Amassian, Aram; Barlow, Stephen; Marder, Seth R.

2016-01-01

Poly(3-hexylthiophene) (P3HT) films and P3HT / fullerene photovoltaic cells have been p-doped with very low levels (< 1 wt. %) of molybdenum tris[1-(trifluoromethylcarbonyl)- 2-(trifluoromethyl)-ethane-1,2-dithiolene]. The dopants are inhomogenously distributed within doped P3HT films, both laterally and as a function of depth, and appear to aggregate in some instances. Doping also results in subtle changes in the local and long range order of the P3HT film. These effects likely contribute to the complexity of the observed evolutions in conductivity, mobility and work function with doping levels. They also negatively affect the open-circuit voltage and fill factor of solar cells in unexpected ways, indicating that dopant aggregation and non-uniform distribution can harm device performance.

Study on the crystallization of multiarm stars with a poly(ethyleneimine) core and poly(ϵ-caprolactone) arms of different length

Energy Technology Data Exchange (ETDEWEB)

Díaz, Angélica; Bacaicoa, Anna; Casas, Maria Teresa; Franco, Lourdes [Departament d’Enginyeria Química, Universitat Politècnica de Catalunya, Av. Diagonal 647, Barcelona E-08028 (Spain); Serra, Angels [Departament de Química Analítica i Química Orgànica, Universitat Rovira i Virgili. C. Marcel.lí Domingo, s/n. Campus Sescelades, Tarragona 43007 (Spain); Puiggalí, Jordi, E-mail: Jordi.Puiggali@upc.edu [Departament d’Enginyeria Química, Universitat Politècnica de Catalunya, Av. Diagonal 647, Barcelona E-08028 (Spain)

2015-05-10

Highlights: • Isothermal crystallization kinetics of multiarm stars. • Influence of the length of poly(ϵ-caprolactone) arms on crystallization kinetics. • Influence of the length of poly(ϵ-caprolactone) arms on secondary nucleation constant. • Crystallization of mixtures of stars having different arm lengths. - Abstract: Crystallization of multiarm star systems constituted by a core of poly(ethyleneimine) (PEI) and arms of poly(ϵ-caprolactone) (PCL) was studied by transmission electron microscopy, calorimetry and optical microscopy techniques. Three systems differing on the degree of polymerization of PCL were studied as well as binary mixtures constituted by systems differing on the length of PCL arms. Samples were able to crystallize from both diluted solutions and the melt state giving rise to well-formed lamellae and spherulites, respectively. Lamellae of samples with large PCL arms were highly regular and corresponded to elongated hexagonal crystals with an aspect ratio that decreased with the length of PCL arms. A significant decrease on equilibrium melting temperatures, degree of crystallinity and glass transition temperature was detected for samples having short PCL arms. Crystallization kinetics were also highly influenced by the length of PCL arms, being both nucleation density and secondary nucleation constant increased as the length of PCL arms decreased. Crystallization of star mixtures having different PCL lengths was determined by the larger arms since they initiated the process and subsequently shorter arms were progressively incorporated. A thermal nucleation was characteristic of multiarm star mixtures due to the different crystallization temperature ranges of samples with large and short PCL arms, whereas samples with a homogeneous arm length rendered an athermal nucleation.

The binding characteristics and orientation of a novel radioligand with distinct properties at 5-HT3A and 5-HT3AB receptors

NARCIS (Netherlands)

Thompson, Andrew J; Verheij, Mark H P; Verbeek, Joost; Windhorst, Albert D; de Esch, Iwan J P; Lummis, Sarah C R

2014-01-01

VUF10166 (2-chloro-3-(4-methyl piperazin-1-yl)quinoxaline) is a ligand that binds with high affinity to 5-HT3 receptors. Here we synthesise [(3)H]VUF10166 and characterise its binding properties at 5-HT3A and 5-HT3AB receptors. At 5-HT3A receptors [(3)H]VUF10166 displayed saturable binding with a Kd

A quantitative correlation between the mobility and crystallinity of photo-cross-linkable P3HT

KAUST Repository

Woo, Claire; Piliego, Claudia; Holcombe, Thomas W.; Toney, Michael F.; Frechet, Jean

2012-01-01

The performance of polymer field effect transistors (FETs) can vary by orders of magnitude by applying different processing conditions. Although it is generally believed that a higher degree of crystallinity results in a higher mobility, the correlation is not straightforward. In addition, the effect of cross-linking on polymer thin film microstructural order is relatively unknown. This study investigates the effect of thermal annealing and UV-initiated photo-cross-linking on the FET performance and microstructural order of a photo-cross-linkable P3HT derivative. Our results demonstrate that while cross-linking did not disrupt the overall crystallinity of the polymer thin film, the photo-cross-linking process likely induced doping in the semiconductor layer, leading to the absence of saturation behavior in the FET. Annealing after cross-linking slightly improved the FET performance but only minimally affected the microstructural order of the polymer film since the 3D morphology had been "locked in" during the first cross-linking step. Importantly, annealing and cross-linking simultaneously was a successful method to preserve polymer crystallinity while also achieving effective cross-linking. Using newly developed quantitative X-ray analysis techniques, our study established a quantitative correlation between FET charge mobility and thin film crystallinity. © 2012 American Chemical Society.

A quantitative correlation between the mobility and crystallinity of photo-cross-linkable P3HT

KAUST Repository

Woo, Claire

2012-04-10

The performance of polymer field effect transistors (FETs) can vary by orders of magnitude by applying different processing conditions. Although it is generally believed that a higher degree of crystallinity results in a higher mobility, the correlation is not straightforward. In addition, the effect of cross-linking on polymer thin film microstructural order is relatively unknown. This study investigates the effect of thermal annealing and UV-initiated photo-cross-linking on the FET performance and microstructural order of a photo-cross-linkable P3HT derivative. Our results demonstrate that while cross-linking did not disrupt the overall crystallinity of the polymer thin film, the photo-cross-linking process likely induced doping in the semiconductor layer, leading to the absence of saturation behavior in the FET. Annealing after cross-linking slightly improved the FET performance but only minimally affected the microstructural order of the polymer film since the 3D morphology had been "locked in" during the first cross-linking step. Importantly, annealing and cross-linking simultaneously was a successful method to preserve polymer crystallinity while also achieving effective cross-linking. Using newly developed quantitative X-ray analysis techniques, our study established a quantitative correlation between FET charge mobility and thin film crystallinity. © 2012 American Chemical Society.

Synthesis of Well-Defined Polyethylene-Based 3-Miktoarm Star Copolymers and Terpolymers

KAUST Repository

Zhang, Zhen

2016-03-25

Novel polyethylene (PE)-based 3-miktoarm star copolymers A2B, (AB)2B and terpolymers (AC)2(BC) [A: PE; B, C: polystyrene (PS) or poly(methyl methacrylate) (PMMA)] were synthesized by combining boron chemistry, polyhomologation, and atom transfer radical polymerization (ATRP). 1,4-Pentadiene-3-yl 2-bromo-2-methylpropanoate was first synthesized followed by hydroboration with thexylborane to afford B-thexylboracyclanes, a multi-heterofunctional initiator with two initiating sites for polyhomologation and one for ATRP. After polyhomologation of dimethylsulfoxonium methylide the α,ω-dihydroxyl polyethylene (PE-OH)2-Br produced served as macroinitiator for the ATRP of styrene to afford (PE-OH)2-(PS-Br). Both (PE-OH)2-Br and (PE-OH)2-(PS-Br) were transformed to two new trifunctional macroinitiators (PE-Br)2-Br and (PE-Br)2-(PS-Br) through esterification reactions and used for the synthesis of (AB)2B and (AC)2(BC) 3-miktoarm star co/terpolymers. All intermediates and final products were characterized by 1H NMR, high temperature gel permeation chromatography (HT-GPC), and differential scanning calorimetry (DSC). The synthetic method is a general one and can be used for the synthesis of complex PE-based architectures by combination with other living/living-controlled polymerization techniques. © 2016 American Chemical Society.

1,2,3,4-bis(p-methylbenzylidene sorbitol) accelerates crystallization and improves hole mobility of poly(3-hexylthiophene)

Science.gov (United States)

Yuan, Nana; Huo, Hong

2016-02-01

The addition of 1,2,3,4-bis(p-methylbenzylidene sorbitol) (MDBS) does not change the nucleation mechanism or the crystal form of poly(3-hexylthiophene) (P3HT), but its presence increases the crystallization temperature (T c) of P3HT, decreases the crystallization half-time (t 1/2) and accelerates P3HT crystallization, which indicates that MDBS is an effective nucleating agent for P3HT. An acceleration of P3HT crystallization by the addition of MDBS decreases the crystalline size and crystallinity of P3HT, and enhances the connectivity between ordered regions of P3HT, leading to the hole mobility rising from 1.99 × 10-6 to 7.57 × 10-5 cm2 V-1s-1 in P3HT:PCBM blend based hole-only devices with sandwich configurations. Our results suggest that accelerating P3HT crystallization by adding a nucleating agent might be an important factor to improve the hole mobility and balance the electron and hole mobility in a photovoltaic blend.

Force-induced desorption of 3-star polymers: a self-avoiding walk model

Science.gov (United States)

Janse van Rensburg, E. J.; Whittington, S. G.

2018-05-01

We consider a simple cubic lattice self-avoiding walk model of 3-star polymers adsorbed at a surface and then desorbed by pulling with an externally applied force. We determine rigorously the free energy of the model in terms of properties of a self-avoiding walk, and show that the phase diagram includes four phases, namely a ballistic phase where the extension normal to the surface is linear in the length, an adsorbed phase and a mixed phase, in addition to the free phase where the model is neither adsorbed nor ballistic. In the adsorbed phase all three branches or arms of the star are adsorbed at the surface. In the ballistic phase two arms of the star are pulled into a ballistic phase, while the remaining arm is in a free phase. In the mixed phase two arms in the star are adsorbed while the third arm is ballistic. The phase boundaries separating the ballistic and mixed phases, and the adsorbed and mixed phases, are both first order phase transitions. The presence of the mixed phase is interesting because it does not occur for pulled, adsorbed self-avoiding walks. In an atomic force microscopy experiment it would appear as an additional phase transition as a function of force.

Inhibition of human MCF-7 breast cancer cells and HT-29 colon cancer cells by rice-produced recombinant human insulin-like growth binding protein-3 (rhIGFBP-3.

Directory of Open Access Journals (Sweden)

Stanley C K Cheung

Full Text Available BACKGROUND: Insulin-like growth factor binding protein-3 (IGFBP-3 is a multifunctional molecule which is closely related to cell growth, apoptosis, angiogenesis, metabolism and senescence. It combines with insulin-like growth factor-I (IGF-I to form a complex (IGF-I/IGFBP-3 that can treat growth hormone insensitivity syndrome (GHIS and reduce insulin requirement in patients with diabetes. IGFBP-3 alone has been shown to have anti-proliferation effect on numerous cancer cells. METHODOLOGY/PRINCIPAL FINDINGS: We reported here an expression method to produce functional recombinant human IGFBP-3 (rhIGFBP-3 in transgenic rice grains. Protein sorting sequences, signal peptide and endoplasmic reticulum retention tetrapeptide (KDEL were included in constructs for enhancing rhIGFBP-3 expression. Western blot analysis showed that only the constructs with signal peptide were successfully expressed in transgenic rice grains. Both rhIGFBP-3 proteins, with or without KDEL sorting sequence inhibited the growth of MCF-7 human breast cancer cells (65.76 ± 1.72% vs 45.00 ± 0.86%, p < 0.05; 50.84 ± 1.97% vs 45.00 ± 0.86%, p < 0.01 respectively and HT-29 colon cancer cells (65.14 ± 3.84% vs 18.01 ± 13.81%, p < 0.05 and 54.7 ± 9.44% vs 18.01 ± 13.81%, p < 0.05 respectively when compared with wild type rice. CONCLUSION/SIGNIFICANCE: These findings demonstrated the feasibility of producing biological active rhIGFBP-3 in rice using a transgenic approach, which will definitely encourage more research on the therapeutic use of hIGFBP-3 in future.

NITROAROMATIC COMPOUND SENSING APPLICATION OF HEXA-ARMED DANSYL END-CAPPED POLY(epsilon-CAPROLACTONE STAR POLYMER WITH PHOSPHAZENE CORE

Directory of Open Access Journals (Sweden)

Merve DANDAN DOGANCI

2016-09-01

Full Text Available Hexa-armed dansyl end-capped poly(ε-caprolactone star polymer with phosphazene core (N3P3-(PCL-Dansyl6 was prepared in a two-step synthetic procedure including ring opening polymerization (ROP of ε-caprolactone (ε-CL and esterification reactions. The obtained fluorescence-active polymer was employed as a fluorescent probe towards certain nitroaromatic compounds (2,4,6-trinitrotoluene (TNT, 2,4-dinitrotoluene, 2,6-dinitrotoluene, 2-nitrotoluene, 3-nitrotoluene, 2,4,6-trinitrophenol (picric acid, 2,4-dinitrophenol, 4-nitrophenol, and 1,2-dinitrobenzene. Fluorescence intensity of N3P3-(PCL-Dansyl6 was decreased gradually upon the addition of nitroaromatic compounds and the highest quenching efficiency was found to be 100% with TNT. Besides, N3P3-(PCL-Dansyl6 gave exceptionally selective response toward nitroaromatic compounds, even in the presence of toxic metal cations such as Pb2+, Co2+, Hg2+, Mn2+, Cd2+ and Zn2+.

Up in arms: Immune and nervous system response to sea star wasting disease

Science.gov (United States)

Fuess, Lauren E; Eiselord, Morgan E.; Closek, Collin J.; Tracy, Allison M.; Mauntz, Ruth; Gignoux-Wolfsohn, Sarah; Moritsch, Monica M; Yoshioka, Reyn; Burge, Colleen A.; Harvell, Drew; Friedman, Carolyn S.; Hershberger, Paul K.; Roberts, Steven B.

2015-01-01

Echinoderms, positioned taxonomically at the base of deuterostomes, provide an important system for the study of the evolution of the immune system. However, there is little known about the cellular components and genes associated with echinoderm immunity. The 2013–2014 sea star wasting disease outbreak is an emergent, rapidly spreading disease, which has led to large population declines of asteroids in the North American Pacific. While evidence suggests that the signs of this disease, twisting arms and lesions, may be attributed to a viral infection, the host response to infection is still poorly understood. In order to examine transcriptional responses of the sea star Pycnopodia helianthoides to sea star wasting disease, we injected a viral sized fraction (0.2 μm) homogenate prepared from symptomatic P. helianthoides into apparently healthy stars. Nine days following injection, when all stars were displaying signs of the disease, specimens were sacrificed and coelomocytes were extracted for RNA-seq analyses. A number of immune genes, including those involved in Toll signaling pathways, complement cascade, melanization response, and arachidonic acid metabolism, were differentially expressed. Furthermore, genes involved in nervous system processes and tissue remodeling were also differentially expressed, pointing to transcriptional changes underlying the signs of sea star wasting disease. The genomic resources presented here not only increase understanding of host response to sea star wasting disease, but also provide greater insight into the mechanisms underlying immune function in echinoderms.

PARALLAXES FOR W49N AND G048.60+0.02: DISTANT STAR FORMING REGIONS IN THE PERSEUS SPIRAL ARM

Energy Technology Data Exchange (ETDEWEB)

Zhang, B.; Menten, K. M.; Brunthaler, A. [Max-Plank-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Reid, M. J.; Dame, T. M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Zheng, X. W. [Department of Astronomy, Nanjing University, Nanjing 210093 (China); Xu, Y. [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

2013-09-20

We report trigonometric parallax measurements of 22 GHz H{sub 2}O masers in two massive star-forming regions from Very Long Baseline Array observations as part of the Bar and Spiral Structure Legacy Survey. The distances of 11.11{sup +0.79}{sub -0.69} kpc to W49N (G043.16+0.01) and 10.75{sup +0.61}{sub -0.55} kpc to G048.60+0.02 locate them in a distant section of the Perseus arm near the solar circle in the first Galactic quadrant. This allows us to locate accurately the inner portion of the Perseus arm for the first time. Combining the present results with sources measured in the outer portion of the arm in the second and third quadrants yields a global pitch angle of 9.°5 ± 1.°3 for the Perseus arm. We have found almost no H{sub 2}O maser sources in the Perseus arm for 50° arm has little massive star formation activity.

Synthesis and luminescent properties of star-burst D-π-A compounds based on 1,3,5-triazine core and carbazole end-capped phenylene ethynylene arms

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zheng [Department of Applied Chemistry, Nanjing Tech University, Nanjing 210009 (China); Liu, Rui, E-mail: rui.liu@njtech.edu.cn [Department of Applied Chemistry, Nanjing Tech University, Nanjing 210009 (China); Zhu, Xiaolin [Department of Applied Chemistry, Nanjing Tech University, Nanjing 210009 (China); Li, Yuhao [Department of Chemistry, Fudan University, 220 Handan Road, Shanghai 200433 (China); Chang, Jin [Queensland University of Technology, 2 George St., Brisbane 4000 (Australia); Zhu, Hongjun, E-mail: zhuhjnjut@hotmail.com [Department of Applied Chemistry, Nanjing Tech University, Nanjing 210009 (China); Ma, Liangwei; Lv, Wangjie; Guo, Jun [Department of Applied Chemistry, Nanjing Tech University, Nanjing 210009 (China)

2014-12-15

Two new star-burst compounds based on 1,3,5-triazine core and carbazole end-capped phenylene ethynylene arms (1a and 1b) were synthesized and characterized. Their photophysical properties were investigated systematically via spectroscopic and theoretical methods. Both compounds exhibit strong {sup 1}π–π{sup ⁎} transitions in the UV region and intense {sup 1}π–π{sup ⁎}/intramolecular charge transfer ({sup 1}ICT) absorption bands in the UV–vis region. Introducing the carbazole end-capped phenylene ethynylene arm on the 1,3,5-triazine core causes a slight bathochromic shift and enhanced molar extinction coefficient of the {sup 1}π–π{sup ⁎}/{sup 1}ICT transition band. Both compounds are emissive in solution at room temperature and 77 K, which exhibit pronounced positive solvatochromic effect. The emitting state could be ascribed to {sup 1}ICT state in more polar solvent, and {sup 1}π–π{sup ⁎} state in low-polarity solvent. The high emission quantum yields (Φ{sub em}=0.90∼1.0) of 1a and 1b (in hexane and toluene) make them potential candidates as efficient light-emitting materials. The spectroscopic studies and theoretical calculations indicate that the photophysical properties of these compounds can be tuned by the carbazole end-capped phenylene ethynylene arm, which would also be useful for rational design of photofunctional materials. - Highlights: • Star-burst compounds based on 1,3,5-triazine core and carbazole end-capped phenylene ethynylene arms. • Photophysical properties of target compounds were investigated systematically via spectroscopic and theoretical methods. • The relatively high fluorescence quantum yields make them potential candidates as light-emitting materials.

THE CHEMISTRY OF THE TRAILING ARM OF THE SAGITTARIUS DWARF GALAXY

International Nuclear Information System (INIS)

Keller, Stefan C.; Yong, David; Da Costa, Gary S.

2010-01-01

We present abundances of C, O, Ti, and Fe for 11 M-giant stars in the trailing tidal arm of the Sagittarius dwarf (Sgr). The abundances were derived by comparing synthetic spectra with high-resolution infrared spectra obtained with the Phoenix spectrograph on the Gemini South telescope. The targeted stars are drawn from two regions of the Sgr trailing arm separated by 66 0 (five stars) and 132 0 (six stars) from the main body of Sgr. The trailing arm provides a more direct diagnostic of the chemical evolution of Sgr compared to the extensively phase-mixed leading arm. Within our restricted sample of ∼2-3 Gyr old stars, we find that the stream material exhibits a significant metallicity gradient of -(2.4 ± 0.3) x 10 -3 dex/degree (-(9.4 ± 1.1) x 10 -4 dex/kpc) away from the main body of Sgr. The tidal disruption of Sgr is a relatively recent event. We therefore interpret the presence of a metallicity gradient in the debris as indicative of a similar gradient in the progenitor. The fact that such a metallicity gradient survived for almost a Hubble time indicates that the efficiency of radial mixing was very low in the Sgr progenitor. No significant gradient is seen to exist in the [α/Fe] abundance ratio along the trailing arm. Our results may be accounted for by a radial decrease in star formation efficiency and/or radial increase in the efficiency of galactic wind-driven metal loss in the chemical evolution of the Sgr progenitor. The [Ti/Fe] and [O/Fe] abundance ratios observed within the stream are distinct from those of the Galactic halo. We conclude that the fraction of the intermediate to metal-rich halo population contributed by the recent dissolution (<3 Gyr) of Sgr-like dwarf galaxies cannot be substantial.

Dynamical effects of the spiral arms on the velocity distribution of disc stars

Science.gov (United States)

Hattori, Kohei; Gouda, Naoteru; Yano, Taihei; Sakai, Nobuyuki; Tagawa, Hiromichi

2018-04-01

Nearby disc stars in Gaia DR1 (TGAS) and RAVE DR5 show a bimodal velocity distribution in the metal-rich region (characterized by the Hercules stream) and mono-modal velocity distribution in the metal-poor region. We investigate the origin of this [Fe/H] dependence of the local velocity distribution by using 2D test particle simulations. We found that this [Fe/H] dependence can be well reproduced if we assume fast rotating bar models with Ωbar ~= 52 km s-1 kpc-1. A possible explanation for this result is that the metal-rich, relatively young stars are more likely to be affected by bar's outer Lindblad resonance due to their relatively cold kinematics. We also found that slowly rotating bar models with Ωbar ~= 39 km s-1 kpc-1 can not reproduce the observed data. Interestingly, when we additionally consider spiral arms, some models can reproduce the observed velocity distribution even when the bar is slowly rotating.

Delay-dependent working memory impairment in young-adult and aged 5-HT1BKO mice as assessed in a radial-arm water maze.

Science.gov (United States)

Wolff, Mathieu; Benhassine, Narimane; Costet, Pierre; Hen, Rene; Segu, Louis; Buhot, Marie-Christine

2003-01-01

Serotonin (5-HT) plays a modulatory role in mnemonic functions, especially by interacting with the cholinergic system. The 5-HT1B receptor is a key target of this interaction. The 5-HT1B receptor knockout mice were found previously to exhibit a facilitation in hippocampal-dependent spatial reference memory learning. In the present study, we submitted mice to a delayed spatial working memory task, allowing the introduction of various delays between an exposure trial and a test trial. The 5-HT1BKO and wild-type mice learned the task in a radial-arm water maze (returning to the most recent presented arm containing the escape platform), and exhibited a high level of performance at delays of 0 and 5 min. However, at the delay of 60 min, only 5-HT1BKO mice exhibited an impairment. At a delay of 90 min, all mice were impaired. Treatment by scopolamine (0.8 mg/kg) induced the same pattern of performance in wild type as did the mutation for short (5 min, no impairment) and long (60 min, impairment) delays. The 22-month-old wild-type and knockout mice exhibited an impairment at short delays (5 and 15 min). The effect of the mutation affected both young-adult and aged mice at delays of 15, 30, and 60 min. Neurobiological data show that stimulation of the 5-HT1B receptor inhibits the release of acetylcholine in the hippocampus, but stimulates this in the frontal cortex. This dual function might, at least in part, explain the opposite effect of the mutation on reference memory (facilitation) and delay-dependent working memory (impairment). These results support the idea that cholinergic-serotonergic interactions play an important role in memory processes.

5-HT3 and 5-HT4 antagonists inhibit peristaltic contractions in guinea-pig distal colon by mechanisms independent of endogenous 5-HT

Directory of Open Access Journals (Sweden)

Tiong Cheng Sia

2013-08-01

Full Text Available Recent studies have shown that endogenous serotonin is not required for colonic peristalsis in vitro, nor gastrointestinal (GI transit in vivo. However, antagonists of 5-Hydroxytryptamine (5-HT receptors can inhibit peristalsis and GI-transit in mammals, including humans. This raises the question of how these antagonists inhibit GI-motility and transit, if depletion of endogenous 5-HT does not cause any significant inhibitory changes to either GI-motility or transit ? We investigated the mechanism by which 5-HT3 and 5-HT4 antagonists inhibit distension-evoked peristaltic contractions in guinea-pig distal colon. In control animals, repetitive peristaltic contractions of the circular muscle were evoked in response to fixed fecal pellet distension. Distension-evoked peristaltic contractions were unaffected in animals with mucosa and submucosal plexus removed, that were also treated with reserpine (to deplete neuronal 5-HT. In control animals, peristaltic contractions were blocked temporarily by ondansetron (1-10µM and SDZ-205-557 (1-10µM in many animals. Interestingly, after this temporary blockade, and whilst in the continued presence of these antagonists, peristaltic contractions recovered, with characteristics no different from controls. Surprisingly, similar effects were seen in mucosa-free preparations, which had no detectable 5-HT, as detected by mass spectrometry. In summary, distension-evoked peristaltic reflex contractions of the circular muscle layer of the guinea-pig colon can be inhibited temporarily, or permanently, in the same preparation by selective 5-HT3 and 5-HT4 antagonists, depending on the concentration of the antagonists applied. These effects also occur in preparations that lack any detectable 5-HT. We suggest caution should be exercised when interpreting the effects of 5-HT3 and 5-HT4 antagonists; and the role of endogenous 5-HT, in the generation of distension-evoked colonic peristalsis.

Thermal-induced changes on the properties of spin-coated P3HT:C60 thin films for solar cell applications

CSIR Research Space (South Africa)

Motaung, DE

2009-09-01

Full Text Available on the properties of spin- coated P3HT:C60 thin films for solar cell applications David E. Motaung1, 2, Gerald F. Malgas1,*, Christopher J. Arendse1, Sipho E. Mavundla1, 3 Clive J. Oliphant 1, 2 and Dirk Knoesen2 1National Centre for Nano...-structured Materials, Council for Scientific Industrial Research, P. O. Box 395, Pretoria, 0001, South Africa 2Deparment of Physics, University of the Western Cape, Private Bag X17, Bellville, 7535, South Africa 3Deparment of Chemistry, University of the Western...

Analysis of the 5-HT receptor in rabbit saphenous vein exemplifies the problems of using exclusion criteria for receptor classification.

Science.gov (United States)

Martin, G R; MacLennan, S J

1990-08-01

5-Hydroxytryptamine (5-HT) contracts ring preparations of rabbit saphenous vein via direct and indirect components, the latter being compatible with a "tyramine-like" action at sympathetic nerve terminals. Here an attempt was made to establish the identity of the receptor mediating contraction directly, in terms of the currently accepted proposals (Bradley et al. 1986). Results with agonists suggested 5-HT1-like receptor activation: methylsergide behaved as a partial agonist with microcolar affinity and 5-HT effects were mimicked by 5-carboxamidotryptamine (5-CT) and GR43175. The agonist potency order was 5-CT greater than 5-HT greater than methysergide greater than or equal to GR43175, the same as that reported at the 5-HT1-like receptor in dog saphenous vein (Feniuk et al. 1985; Humphrey et al. 1988). Consistent with this, 5-HT effects were resistant to blockade by the selective 5-HT3 receptor antagonist MDL72222 (1.0 mumol/l). In contrast, methiothepin (0.01-0.3 mumol/l), ketanserin (0.3-30.0 mumol/l) and spiperone (0.3-30.0 mumol/l) each produced surmountable antagonism which, although competitive in nature only for methiothepin (pKB = 9.45 +/- 0.09, 17 d.f.), implied 5-HT2 receptor involvement. The possibility that these discrepancies resulted from mixed populations of 5-HT1-like and 5-HT2 receptors can be excluded because; 1). Ketanserin and spiperone blocked the actions of 5-HT and the selective 5-HT1-like receptor agonist GR43175 with equal facility and 2). Responses to all of the agonists studied were similarly antagonised by flesinoxan (pKB approximately 6.4), a simple competitive antagonist at the receptor in rabbit saphenous vein.(ABSTRACT TRUNCATED AT 250 WORDS)

Deposit heterogeneity and the dynamics of the organic semiconductors P3HT and PCBM solution under evaporation

Science.gov (United States)

Yu, H. P.; Luo, H.; Liu, T. T.; Jing, G. Y.

2015-04-01

The formation of organic semiconductor layer is the key procedure in the manufacture of organic photovoltaic solar cell, in which the natural evaporation of the solvent from the polymer solution plays the essential role for the conversion efficiency. Here, poly(3-hexylthiophene) (P3HT) and fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), as two types of semiconductor polymers, were selected as the active layer to form the deposit by drying the blend solution drops on the substrate. We explored the influences of droplet size and solute concentration on the homogeneity of the deposit. Additionally, the spatial distribution of molecular chains and grains and the instability of the droplet morphology during the drying were investigated. The results showed that the "coffee-ring" phenomenon occurred forming an annular deposit at the outermost edge and the width of the annular ring increased linearly with the concentration of the P3HT solution, until a saturation plateau is approached. On the other hand, the PCBM deposition presented a circular disk at low concentration, but displayed a sudden instability for an irregular perimeter at a critical concentration and there existed a second critical concentration above which the deposit exhibited the return of the stable circular shape. The results have an instructive impact on the performance of the device and the formation of fine structures during the process of printing, film preparation and painting.

Subnanosecond Charge Recombination Dynamics in P3HT/PC61BM Films

Directory of Open Access Journals (Sweden)

Jian-Ping Zhang

2012-11-01

Full Text Available Ultrafast near-infrared absorption spectroscopy was used to investigate the influence of film morphology and excitation photon energy on the charge recombination (CR dynamics in the initial nanosecond timescale in the P3HT/PC61BM blend films. With reference to the CS2-cast films, the solvent vapor annealed (SVA ones show 2–3-fold improvement in hole mobility and more than 5-fold reduction in the polymer-localized trap states of holes. At Dt = 70 ps, the hole mobility (mh and the bimolecular CR rate (gbi of the SVA films are mh = 8.7 × 10−4 cm2×s−1×V−1 and gbi = 4.5 × 10−10 cm3×s−1, whereas at Dt = 1 ns they drop to 8.7 × 10−5 cm2×s−1×V−1 and 4.6 × 10−11 cm3×s−1, respectively. In addition, upon increasing the hole concentration, the hole mobility increases substantially faster under the above-gap photoexcitation than it does under the band-gap photoexcitation, irrespective of the film morphologies. The results point to the importance of utilizing the photogenerated free charges in the early timescales.

Enhancement of cortical extracellular 5-HT by 5-HT1A and 5-HT2C receptor blockade restores the antidepressant-like effect of citalopram in non-responder mice.

Science.gov (United States)

Calcagno, Eleonora; Guzzetti, Sara; Canetta, Alessandro; Fracasso, Claudia; Caccia, Silvio; Cervo, Luigi; Invernizzi, Roberto W

2009-07-01

We recently found that the response of DBA/2 mice to SSRIs in the forced swim test (FST) was impaired and they also had a smaller basal and citalopram-stimulated increase in brain extracellular serotonin (5-HT) than 'responder' strains. We employed intracerebral microdialysis, FST and selective antagonists of 5-HT1A and 5-HT2C receptors to investigate whether enhancing the increase in extracellular 5-HT reinstated the anti-immobility effect of citalopram in the FST. WAY 100635 (0.3 mg/kg s.c.) or SB 242084 (1 mg/kg s.c.), respectively a selective 5-HT1A and 5-HT2C receptor antagonist, raised the effect of citalopram (5 mg/kg) on extracellular 5-HT in the medial prefrontal cortex of DBA/2N mice (citalopram alone 5.2+/-0.3 fmol/20 microl, WAY 100635+citalopram 9.9+/-2.1 fmol/20 microl, SB 242084+ citalopram 7.6+/-1.0 fmol/20 microl) to the level reached in 'responder' mice given citalopram alone. The 5-HT receptor antagonists had no effect on the citalopram-induced increase in extracellular 5-HT in the dorsal hippocampus. The combination of citalopram with WAY 100635 or SB 242084 significantly reduced immobility time in DBA/2N mice that otherwise did not respond to either drug singly. Brain levels of citalopram in mice given citalopram alone or with 5-HT antagonists did not significantly differ. The results confirm that impaired 5-HT transmission accounts for the lack of effect of citalopram in the FST and suggest that enhancing the effect of SSRIs on extracellular 5-HT, through selective blockade of 5-HT1A and 5-HT2C receptors, could be a useful strategy to restore the response in treatment-resistant depression.

WASP-12b AND HAT-P-8b are members of triple star systems

Energy Technology Data Exchange (ETDEWEB)

Bechter, Eric B.; Crepp, Justin R.; Matthews, Christopher T. [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Ngo, Henry; Knutson, Heather A.; Batygin, Konstantin; Johnson, John Asher [Department of Planetary Science, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Hinkley, Sasha; Muirhead, Philip S.; Montet, Benjamin T.; Morton, Timothy D. [Department of Astronomy, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Howard, Andrew W., E-mail: ebechter@nd.edu [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

2014-06-10

We present high spatial resolution images that demonstrate that WASP-12b and HAT-P-8b orbit the primary stars of hierarchical triple star systems. In each case, two distant companions with colors and brightnesses consistent with M dwarfs co-orbit the hot Jupiter planet host as well as one another. Our adaptive optics images spatially resolve the secondary around WASP-12, previously identified by Bergfors et al. and Crossfield et al. into two distinct sources separated by 84.3 ± 0.6 mas (21 ± 3 AU). We find that the secondary to HAT-P-8, also identified by Bergfors et al., is in fact composed of two stars separated by 65.3 ± 0.5 mas (15 ± 1 AU). Our follow-up observations demonstrate physical association through common proper motion. HAT-P-8 C has a particularly low mass, which we estimate to be 0.18 ± 0.02 M {sub ☉} using photometry. Due to their hierarchy, WASP-12 BC and HAT-P-8 BC will enable the first dynamical mass determination for hot Jupiter stellar companions. These previously well studied planet hosts now represent higher-order multi-star systems with potentially complex dynamics, underscoring the importance of diffraction-limited imaging and providing additional context for understanding the migrant population of transiting hot Jupiters.

WASP-12b and HAT-P-8b are Members of Triple Star Systems

Science.gov (United States)

Bechter, Eric B.; Crepp, Justin R.; Ngo, Henry; Knutson, Heather A.; Batygin, Konstantin; Hinkley, Sasha; Muirhead, Philip S.; Johnson, John Asher; Howard, Andrew W.; Montet, Benjamin T.; Matthews, Christopher T.; Morton, Timothy D.

2014-06-01

We present high spatial resolution images that demonstrate that WASP-12b and HAT-P-8b orbit the primary stars of hierarchical triple star systems. In each case, two distant companions with colors and brightnesses consistent with M dwarfs co-orbit the hot Jupiter planet host as well as one another. Our adaptive optics images spatially resolve the secondary around WASP-12, previously identified by Bergfors et al. and Crossfield et al. into two distinct sources separated by 84.3 ± 0.6 mas (21 ± 3 AU). We find that the secondary to HAT-P-8, also identified by Bergfors et al., is in fact composed of two stars separated by 65.3 ± 0.5 mas (15 ± 1 AU). Our follow-up observations demonstrate physical association through common proper motion. HAT-P-8 C has a particularly low mass, which we estimate to be 0.18 ± 0.02 M ⊙ using photometry. Due to their hierarchy, WASP-12 BC and HAT-P-8 BC will enable the first dynamical mass determination for hot Jupiter stellar companions. These previously well studied planet hosts now represent higher-order multi-star systems with potentially complex dynamics, underscoring the importance of diffraction-limited imaging and providing additional context for understanding the migrant population of transiting hot Jupiters.

WASP-12b AND HAT-P-8b are members of triple star systems

International Nuclear Information System (INIS)

Bechter, Eric B.; Crepp, Justin R.; Matthews, Christopher T.; Ngo, Henry; Knutson, Heather A.; Batygin, Konstantin; Johnson, John Asher; Hinkley, Sasha; Muirhead, Philip S.; Montet, Benjamin T.; Morton, Timothy D.; Howard, Andrew W.

2014-01-01

We present high spatial resolution images that demonstrate that WASP-12b and HAT-P-8b orbit the primary stars of hierarchical triple star systems. In each case, two distant companions with colors and brightnesses consistent with M dwarfs co-orbit the hot Jupiter planet host as well as one another. Our adaptive optics images spatially resolve the secondary around WASP-12, previously identified by Bergfors et al. and Crossfield et al. into two distinct sources separated by 84.3 ± 0.6 mas (21 ± 3 AU). We find that the secondary to HAT-P-8, also identified by Bergfors et al., is in fact composed of two stars separated by 65.3 ± 0.5 mas (15 ± 1 AU). Our follow-up observations demonstrate physical association through common proper motion. HAT-P-8 C has a particularly low mass, which we estimate to be 0.18 ± 0.02 M ☉ using photometry. Due to their hierarchy, WASP-12 BC and HAT-P-8 BC will enable the first dynamical mass determination for hot Jupiter stellar companions. These previously well studied planet hosts now represent higher-order multi-star systems with potentially complex dynamics, underscoring the importance of diffraction-limited imaging and providing additional context for understanding the migrant population of transiting hot Jupiters.

P3HT:PCBM Incorporated with Silicon Nanoparticles as Photoactive Layer in Efficient Organic Photovoltaic Devices

Directory of Open Access Journals (Sweden)

Shang-Chou Chang

2013-01-01

Full Text Available Silicon nanoparticles doped poly(3-hexylthiophene and [6,6]-phenyl C61-butyric acid methyl ester blends (P3HT:PCBM: Si NP have been produced as the photoactive layer of organic photovoltaic devices (OPVs. The silicon nanoparticles’ size is between 80 and 100 nm checked by transmission electron microscope (TEM. The 0.35 wt% Si NP doping OPVs exhibit higher power conversion efficiency (PCE than other OPVs. The PCE of the OPVs increases from 3.01% to 3.38% mainly due to increasing short-circuit current density from 8.38 to 9.48 mA/cm2, while the open-circuit voltage remains the same. The Si NP can provide extra exciton separation and electron pathways in hybrid solar cells.

The inhibition of cholera toxin-induced 5-HT release by the 5-HT3 receptor antagonist, granisetron, in the rat

Science.gov (United States)

Turvill, J L; Connor, P; Farthing, M J G

2000-01-01

The secretagogue 5-hydroxytryptamine (5-HT) is implicated in the pathophysiology of cholera. 5-HT released from enterochromaffin cells after cholera toxin exposure is thought to activate non-neuronally (5-HT2 dependent) and neuronally (5-HT3 dependent) mediated water and electrolyte secretion. CT-secretion can be reduced by preventing the release of 5-HT. Enterochromaffin cells possess numerous receptors that, under basal conditions, modulate 5-HT release. These include basolateral 5-HT3 receptors, the activation of which is known to enhance 5-HT release. Until now, 5-HT3 receptor antagonists (e.g. granisetron) have been thought to inhibit cholera toxin-induced fluid secretion by blockading 5-HT3 receptors on secretory enteric neurones. Instead we postulated that they act by inhibiting cholera toxin-induced enterochromaffin cell degranulation. Isolated intestinal segments in anaesthetized male Wistar rats, pre-treated with granisetron 75 μg kg−1, lidoocaine 6 mg kg−1 or saline, were instilled with a supramaximal dose of cholera toxin or saline. Net fluid movement was determined by small intestinal perfusion or gravimetry and small intestinal and luminal fluid 5-HT levels were determined by HPLC with fluorimetric detection. Intraluminal 5-HT release was proportional to the reduction in tissue 5-HT levels and to the onset of water and electrolyte secretion, suggesting that luminal 5-HT levels reflect enterochromaffin cell activity. Both lidocaine and granisetron inhibited fluid secretion. However, granisetron alone, and proportionately, reduced 5-HT release. The simultaneous inhibition of 5-HT release and fluid secretion by granisetron suggests that 5-HT release from enterochromaffin cells is potentiated by endogenous 5-HT3 receptors. The accentuated 5-HT release promotes cholera toxin-induced fluid secretion. PMID:10882387

New Low-Bandgap Materials with Good Stabilities and Efficiencies Comparable to P3HT in R2R-Coated Solar Cells

DEFF Research Database (Denmark)

Søndergaard, Roar; Manceau, Matthieu; Jørgensen, Mikkel

2012-01-01

Roll-to-roll coated organic solar cells of two new polymers processed in ambient conditions show good photochemical stabilities, and their efficiencies are comparable to similar roll-to-roll coated P3HT cells. Optimal blend compositions are achieved by the use of differentially pumped slot die...

Structure of the S6 spirel arm in the Andromeda galaxy

International Nuclear Information System (INIS)

Efremov, Yu.N.

1982-01-01

The distribution of stars across the spiral arm S6 in M 31 within Baade's Field 4 is investigated. It is found that the brightest stars are concentrated to the middle line of the arm where the maximal star density is also observed. The symmetry of the arm S6 may be explained by its position near the corotation radius that followed from the spiral pattern velocity Ωsub(P) approximately 10 km/s kpc determined by the age gradient in the arm S4. The similarity between the structure of the arm S6 and that of the spiral arms near the Sun is pointed out [ru

Chemical Composition of Young Stars in the Leading Arm of the Magellanic System

Energy Technology Data Exchange (ETDEWEB)

Zhang, Lan; Zhao, Gang [Key Lab. of Optical Astronomy, National Astronomical Observatories, CAS, 20A Datun Road, Chaoyang District, 100012 Beijing (China); Moni Bidin, Christian [Instituto de Astronomía, Universidad Católica del Norte, Av. Angomos 0610, Antofagasta (Chile); Casetti-Dinescu, Dana I. [Department of Physics, Southern Connecticut State University, 501 Crescent Street, New Haven, CT 06515 (United States); Méndez, Réne A. [Departamento de Astronomia Universidad de Chile, Camino El Observatorio #1515, Las Condes, Santiago (Chile); Girard, Terrence M. [14 Dunn Rd, Hamden, Connecticut, CT 06518 (United States); Korchagin, Vladimir I. [Institute of Physics, Southern Federal University, Stachki st/194, 344090, Rostov-on-Don (Russian Federation); Vieira, Katherine; Van Altena, William F. [Centro de Investigaciones de Astronomiá, Apartado Postal 264, Mérida 5101-A (Venezuela, Bolivarian Republic of)

2017-02-01

Chemical abundances of eight O- and B-type stars are determined from high-resolution spectra obtained with the MIKE instrument on the Magellan 6.5 m Clay telescope. The sample is selected from 42 candidates for membership in the Leading Arm (LA) of the Magellanic System. Stellar parameters are measured by two independent grids of model atmospheres and analysis procedures, confirming the consistency of the stellar parameter results. Abundances of seven elements (He, C, N, O, Mg, Si, and S) are determined for the stars, as are their radial velocities and estimates of distances and ages. Among the seven B-type stars analyzed, the five that have radial velocities compatible with membership of the LA have an average [Mg/H] of −0.42 ± 0.16, significantly lower than the average of the remaining two, [Mg/H] = −0.07±0.06, which are kinematical members of the Galactic disk. Among the five LA members, four have individual [Mg/H] abundance compatible with that in the LMC. Within errors, we cannot exclude the possibility that one of these stars has an [Mg/H] consistent with the more metal-poor, SMC-like material. The remaining fifth star has an [Mg/H] close to Milky Way values. Distances to the LA members indicate that they are at the edge of the Galactic disk, while ages are of the order of ∼50–70 Myr, lower than the dynamical age of the LA, suggesting a single star-forming episode in the LA. V {sub LSR} of the LA members decreases with decreasing Magellanic longitude, confirming the results of previous LA gas studies.

Evidence that the atypical 5-HT3 receptor ligand, [3H]-BRL46470, labels additional 5-HT3 binding sites compared to [3H]-granisetron.

Science.gov (United States)

Steward, L. J.; Ge, J.; Bentley, K. R.; Barber, P. C.; Hope, A. G.; Lambert, J. J.; Peters, J. A.; Blackburn, T. P.; Barnes, N. M.

1995-01-01

1. The radioligand binding characteristics of the 3H-derivative of the novel 5-HT3 receptor antagonist BRL46470 were investigated and directly compared to the well characterized 5-HT3 receptor radioligand [3H]-granisetron, in tissue homogenates prepared from rat cerebral cortex/hippocampus, rat ileum, NG108-15 cells, HEK-5-HT3As cells and human putamen. 2. In rat cerebral cortex/hippocampus, rat ileum, NG108-15 cell and HEK-5-HT3As cell homogenates, [3H]-BRL46470 bound with high affinity (Kd (nM): 1.57 +/- 0.18, 2.49 +/- 0.30, 1.84 +/- 0.27, 3.46 +/- 0.36, respectively; mean +/- s.e. mean, n = 3-4) to an apparently homogeneous saturable population of sites (Bmax (fmol mg-1 protein): 102 +/- 16, 44 +/- 4, 968 +/- 32 and 2055 +/- 105, respectively; mean +/- s.e. mean, n = 3-4) but failed to display specific binding in human putamen homogenates. 3. In the same homogenates of rat cerebral cortex/hippocampus, rat ileum, NG108-15 cells, HEK-5-HT3As cells and human putamen as used for the [3H]-BRL46470 studies, [3H]-granisetron also bound with high affinity (Kd (nM): 1.55 +/- 0.61, 2.31 +/- 0.44, 1.89 +/- 0.36, 2.03 +/- 0.42 and 6.46 +/- 2.58 respectively; mean +/- s.e. mean, n = 3-4) to an apparently homogeneous saturable population of sites (Bmax (fmol mg-1 protein): 39 +/- 4, 20 +/- 2, 521 +/- 47, 870 +/- 69 and 18 +/- 2, respectively; mean +/- s.e. mean, n = 3-4).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8528560

The antidepressant-like effect of 7-fluoro-1,3-diphenylisoquinoline-1-amine in the mouse forced swimming test is mediated by serotonergic and dopaminergic systems.

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Pesarico, Ana Paula; Sampaio, Tuane Bazanella; Stangherlin, Eluza Curte; Mantovani, Anderson C; Zeni, Gilson; Nogueira, Cristina Wayne

2014-10-03

The aim of the present study was to investigate the role of monoaminergic system in the antidepressant-like action of 7-fluoro-1,3-diphenylisoquinoline-1-amine (FDPI), a derivative of isoquinoline class, in Swiss mice. The antidepressant-like effect of FDPI was characterized in the modified forced swimming test (FST) and the possible mechanism of action was investigated by using serotonergic, dopaminergic and noradrenergic antagonists. Monoamine oxidase (MAO) activity and [(3)H]serotonin (5-HT) uptake were determined in prefrontal cortices of mice. The results showed that FDPI (1, 10 and 20mg/kg, i.g.) reduced the immobility time and increased the swimming time but did not alter climbing time in the modified FST. These effects were similar to those of paroxetine (8mg/kg, i.p.), a positive control. Pretreatments with p-chlorophenylalanine (100mg/kg, i.p., an inhibitor of 5-HT synthesis), WAY100635 (0.1mg/kg, s.c., 5-HT1A antagonist), ondansetron (1mg/kg, i.p., a 5-HT3 receptor antagonist), haloperidol (0.2mg/kg, i.p., a non-selective D2 receptor antagonist) and SCH23390 (0.05mg/kg, s.c., a D1 receptor antagonist) were effective to block the antidepressant-like effect of FDPI at a dose of 1mg/kg in the FST. Ritanserin (1mg/kg, i.p., a 5-HT2A/2C receptor antagonist), sulpiride (50mg/kg, i.p., a D2 and D3 receptor antagonist), prazosin (1mg/kg, i.p., an α1 receptor antagonist), yohimbine (1mg/kg, i.p., an α2 receptor antagonist) and propranolol (2mg/kg, i.p., a β receptor antagonist) did not modify the effect of FDPI in the FST. FDPI did not change synaptosomal [(3)H]5-HT uptake. At doses of 10 and 20mg/kg FDPI inhibited MAO-A and MAO-B activities. These results suggest that antidepressant-like effect of FDPI is mediated mostly by serotonergic and dopaminergic systems. Copyright © 2014 Elsevier Inc. All rights reserved.

Differential Rotation in Sun-like Stars from Surface Variability and Asteroseismology

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Nielsen, Martin Bo

2017-03-01

The Sun and other stars are known to oscillate. Through the study of small perturbations to the frequencies of these oscillations the rotation of the deep interior can be inferred. However, thus far the internal rotation of other Sun-like stars is unknown. The NASA Kepler mission has observed a multitude of Sun-like stars over a period of four years. This has provided high-quality photometric data that can be used to study the rotation of stars with two different techniques: asteroseismology and surface activity. Asteroseismology provides a means of measuring rotation in the stellar interior, while photometric variability from magnetically active regions are sensitive to rotation at the stellar surface. The combination of these two methods can be used to constrain the radial differential rotation in Sun-like stars. First, we developed an automated method for measuring the rotation of stars using surface variability. This method was initially applied to the entire Kepler catalog, out of which we detected signatures of rotation in 12,000 stars across the main sequence, providing robust estimates of the surface rotation rates and the associated errors. Second, we performed an asteroseismic analysis of six Sun-like stars, where we were able to measure the rotational splitting as a function of frequency in the p-mode envelope. This was done by dividing the oscillation spectrum into individual segments, and fitting a model independently to each segment. We found that the measured splittings were all consistent with a constant value, indicating little differential rotation. Third, we compared the asteroseismic rotation rates of five Sun-like stars to their surface rotation rates. We found that the values were in good agreement, again indicating little differential rotation between the regions where the two methods are most sensitive. Finally, we discuss how the surface rotation rates may be used as a prior on the seismic envelope rotation rate in a double-zone model

Fabrication of supramolecular star-shaped amphiphilic copolymers for ROS-triggered drug release.

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Zuo, Cai; Peng, Jinlei; Cong, Yong; Dai, Xianyin; Zhang, Xiaolong; Zhao, Sijie; Zhang, Xianshuo; Ma, Liwei; Wang, Baoyan; Wei, Hua

2018-03-15

Star-shaped copolymers with branched structures can form unimolecular micelles with better stability than the micelles self-assembled from conventional linear copolymers. However, the synthesis of star-shaped copolymers with precisely controlled degree of branching (DB) suffers from complicated sequential polymerizations and multi-step purification procedures, as well as repeated optimizations of polymer compositions. The use of a supramolecular host-guest pair as the block junction would significantly simplify the preparation. Moreover, the star-shaped copolymer-based unimolecular micelle provides an elegant solution to the tradeoff between extracellular stability and intracellular high therapeutic efficacy if the association/dissociation of the supramolecular host-guest joint can be triggered by the biologically relevant stimuli. For this purpose, in this study, a panel of supramolecular star-shaped amphiphilic block copolymers with 9, 12, and 18 arms were designed and fabricated by host-guest complexations between the ring-opening polymerization (ROP)-synthesized star-shaped poly(ε-caprolactone) (PCL) with 3, 4, and 6 arms end-capped with ferrocene (Fc) (PCL-Fc) and the atom transfer radical polymerization (ATRP)-produced 3-arm poly(oligo ethylene glycol) methacrylates (POEGMA) with different degrees of polymerization (DPs) of 24, 30, 47 initiated by β-cyclodextrin (β-CD) (3Br-β-CD-POEGMA). The effect of DB and polymer composition on the self-assembled properties of the five star-shaped copolymers was investigated by dynamic light scattering (DLS), transmission electron microscopy (TEM), and fluorescence spectrometery. Interestingly, the micelles self-assembled from 12-arm star-shaped copolymers exhibited greater stability than the 9- and 18-arm formulations. The potential of the resulting supramolecular star-shaped amphiphilic copolymers as drug carriers was evaluated by an in vitro drug release study, which confirmed the ROS-triggered accelerated drug

Risk-aware multi-armed bandit problem with application to portfolio selection.

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Huo, Xiaoguang; Fu, Feng

2017-11-01

Sequential portfolio selection has attracted increasing interest in the machine learning and quantitative finance communities in recent years. As a mathematical framework for reinforcement learning policies, the stochastic multi-armed bandit problem addresses the primary difficulty in sequential decision-making under uncertainty, namely the exploration versus exploitation dilemma, and therefore provides a natural connection to portfolio selection. In this paper, we incorporate risk awareness into the classic multi-armed bandit setting and introduce an algorithm to construct portfolio. Through filtering assets based on the topological structure of the financial market and combining the optimal multi-armed bandit policy with the minimization of a coherent risk measure, we achieve a balance between risk and return.

A quantitative analysis on the interfacial effect in the Pt/Ba0.5Sr0.5TiO3/La0.67Sr0.33MnO3 heterostructure

International Nuclear Information System (INIS)

Miao, J; Wang, Y; Tian, H Y; Zhou, X Y; Chan, H L W; Choy, C L; Cao, L X; Zhao, B R

2006-01-01

The heterostructure of Pt/Ba 0.5 Sr 0.5 TiO 3 /La 0.67 Sr 0.33 MnO 3 (Pt/BST/LSMO) with the BST thickness ranging from 120 to 550 nm was fabricated by pulsed laser deposition. The dielectric constant (ε) of the heterostructure was measured under different electrical fields (E) and frequency (f). A strong thickness dependence of the value of ε, the ε-E dependence and the ε-f dependence were observed, which can be well explained by the series-capacitor model, based on the assumption that the heterostructure electrically consists of a 'bulk' layer and an interfacial layer between the Pt and BST layers. The dielectric properties of the 'bulk' layer and the interface layer were obtained. At room temperature, the dielectric constant of the 'bulk' layer was 1204 (at 100 kHz) and had a power law dependence on frequency. The ratio of thickness over the dielectric constant (d i /ε i ) of the interface layer, which was used to characterize the property of the Pt/BST interface, was found to be around 0.08 nm at room temperature and to be independent of frequency

Synthesis and serotonergic activity of substituted 2, N-benzylcarboxamido-5-(2-ethyl-1-dioxoimidazolidinyl)-N, N-dimethyltryptamine derivatives: novel antagonists for the vascular 5-HT(1B)-like receptor.

Science.gov (United States)

Moloney, G P; Martin, G R; Mathews, N; Milne, A; Hobbs, H; Dodsworth, S; Sang, P Y; Knight, C; Williams, M; Maxwell, M; Glen, R C

1999-07-15

The synthesis and vascular 5-HT(1B)-like receptor activity of a novel series of substituted 2, N-benzylcarboxamido-5-(2-ethyl-1-dioxoimidazolidinyl)-N, N-dimethyltryptamine derivatives are described. Modifications to the 5-ethylene-linked heterocycle and to substituents on the 2-benzylamide side chain have been explored. Several compounds were identified which exhibited affinity at the vascular 5-HT(1B)-like receptor of pK(B) > 7.0, up to 100-fold selectivity over alpha(1)-adrenoceptor affinity and 5-HT(2A) receptor affinity, and which exhibited a favorable pharmacokinetic profile. N-Benzyl-3-[2-(dimethylamino)ethyl]-5-[2-(4,4-dimethyl-2, 5-dioxo-1-imidazolidinyl)ethyl]-1H-indole-2-carboxamide (23) was identified as a highly potent, silent (as judged by the inability of angiotensin II to unmask 5-HT(1B)-like receptor-mediated agonist activity in the rabbit femoral artery), and competitive vascular 5-HT(1B)-like receptor antagonist with a plasma elimination half-life of approximately 4 h in dog plasma and with good oral bioavailability. The selectivity of compounds from this series for the vascular 5-HT(1B)-like receptors over other receptor subtypes is discussed as well as a proposed mode of binding to the receptor pharmacophore. It has been proposed that the aromatic ring of the 2, N-benzylcarboxamide group can occupy an aromatic binding site rather than the indole ring. The resulting conformation allows an amine-binding site to be occupied by the ethylamine nitrogen and a hydrogen-bonding site to be occupied by one of the hydantoin carbonyls. The electronic nature of the 2,N-benzylcarboxamide aromatic group as well as the size of substituents on this aromatic group is crucial for producing potent and selective antagonists. The structural requirement on the 3-ethylamine side chain incorporating the protonatable nitrogen is achieved by the bulky 2, N-benzylcarboxamide group and its close proximity to the 3-side chain.

Efficient Annealing-Free P3HT:PC_6_1BM-Based Organic Solar Cells by Using a Novel Solvent Additive without a Halogen or Sulphur Atom

International Nuclear Information System (INIS)

Xiao Man-Jun; Zhu Wei-Guo; Shen Wen-Fei; Wang Jun-Yi; Han Liang-Liang; Chen Wei-Chao; Bao Xi-Chang; Yang Ren-Qiang

2015-01-01

The power conversion efficiency (PCE) of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PC_6_1BM) based organic solar cells (OSCs) is significantly improved by using benzyl acetate (BA), an organic compound without any halogen or sulphur atom, as a processing additive to control the blend morphology. The solar cells show PCE of 3.85% with a fill factor (FF) of 65.22%, which are higher than those of the common thermal annealing device (PCE 3.30%, FF 60.83%). The overall increased PCE depends upon the enhanced crystallinity of P3HT and good carriers transport, with a high balanced charge carrier mobility. (cross-disciplinary physics and related areas of science and technology)

In the search for a lead structure among series of potent and selective hydantoin 5-HT7 R agents: The drug-likeness in vitro study.

Science.gov (United States)

Latacz, Gniewomir; Lubelska, Annamaria; Jastrzębska-Więsek, Magdalena; Partyka, Anna; Sobiło, Andrzej; Olejarz, Agnieszka; Kucwaj-Brysz, Katarzyna; Satała, Grzegorz; Bojarski, Andrzej J; Wesołowska, Anna; Kieć-Kononowicz, Katarzyna; Handzlik, Jadwiga

2017-12-01

Since the year 1993, when 5-HT 7 receptor (5-HT 7 R) was discovered, there is no selective 5-HT 7 R ligand introduced to the pharmaceutical market. One out of the main reasons disqualifying the 5-HT 7 R ligands is weak drugability properties, including metabolic instability or low permeability. This study is focused on the search of a lead compound by "drug-likeness" estimation of the first series of selective and potent 5-HT 7 R ligands among 5-(4-fluorophenyl)-3-(2-hydroxy-3-(4-aryl-piperazin-1-yl)propyl)-5-methylimidazolidine-2,4-dione derivatives (11-16). The most important drugability parameters, i.e., permeability, metabolic stability, and safety, have been evaluated. The main metabolic pathways were determined. The forced swim test (FST) in mice was performed as a primary in vivo assay for compound 13 and the reference 2. The experiments showed promising drug-like properties for all ligands, with special attention to the benzhydryl (diphenylmethyl) derivative 13. The studies have also indicated in vivo activity of the compound 13 that was observed as a significant and specific antidepressant-like activity in the FST. Taking into account the beneficial properties of 13, i.e., good drug-like parameters, the significant antagonistic action, high selectivity to 5-HT 7 R, and its in vivo antidepressant-like activity, the compound should be considered as a new lead in the search for drugs acting on CNS via 5-HT 7 receptor. © 2017 John Wiley & Sons A/S.

Regulation of Hippocampal 5-HT Release by P2X7 Receptors in Response to Optogenetic Stimulation of Median Raphe Terminals of Mice

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Flóra Gölöncsér

2017-10-01

Full Text Available Serotonergic and glutamatergic neurons of median raphe region (MRR play a pivotal role in the modulation of affective and cognitive functions. These neurons synapse both onto themselves and remote cortical areas. P2X7 receptors (P2rx7 are ligand gated ion channels expressed by central presynaptic excitatory nerve terminals and involved in the regulation of neurotransmitter release. P2rx7s are implicated in various neuropsychiatric conditions such as schizophrenia and depression. Here we investigated whether 5-HT release released from the hippocampal terminals of MRR is subject to modulation by P2rx7s. To achieve this goal, an optogenetic approach was used to selectively activate subpopulation of serotonergic terminals derived from the MRR locally, and one of its target area, the hippocampus. Optogenetic activation of neurons in the MRR with 20 Hz was correlated with freezing and enhanced locomotor activity of freely moving mice and elevated extracellular levels of 5-HT, glutamate but not GABA in vivo. Similar optical stimulation (OS significantly increased [3H]5-HT and [3H]glutamate release in acute MRR and hippocampal slices. We examined spatial and temporal patterns of [3H]5-HT release and the interaction between the serotonin and glutamate systems. Whilst [3H]5-HT release from MRR neurons was [Ca2+]o-dependent and sensitive to TTX, CNQX and DL-AP-5, release from hippocampal terminals was not affected by the latter drugs. Hippocampal [3H]5-HT released by electrical but not OS was subject to modulation by 5- HT1B/D receptors agonist sumatriptan (1 μM, whereas the selective 5-HT1A agonist buspirone (0.1 μM was without effect. [3H]5-HT released by electrical and optical stimulation was decreased in mice genetically deficient in P2rx7s, and after perfusion with selective P2rx7 antagonists, JNJ-47965567 (0.1 μM, and AZ-10606120 (0.1 μM. Optical and electrical stimulation elevated the extracellular level of ATP. Our results demonstrate for the

Frequency Dependent Electrical and Dielectric Properties of Au/P3HT:PCBM:F4-TCNQ/n-Si Schottky Barrier Diode

Science.gov (United States)

Taşçıoğlu, İ.; Tüzün Özmen, Ö.; Şağban, H. M.; Yağlıoğlu, E.; Altındal, Ş.

2017-04-01

In this study, poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester: 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (P3HT:PCBM:F4-TCNQ) organic film was deposited on n-type silicon (n-Si) substrate by spin coating method. The electrical and dielectric analysis of Au/P3HT:PCBM:F4-TCNQ/n-Si Schottky barrier diode was conducted by means of capacitance-voltage ( C- V) and conductance-voltage ( G/ ω- V) measurements in the frequency range of 10 kHz-2 MHz. The C- V- f plots exhibit fairly large frequency dispersion due to excess capacitance caused by the presence of interface states ( N ss). The values of N ss located in semiconductor bandgap at the organic film/semiconductor interface were calculated by Hill-Coleman method. Experimental results show that dielectric constant ( ɛ') and dielectric loss ( ɛ″) decrease with increasing frequency, whereas loss tangent (tan δ) remains nearly the same. The decrease in ɛ' and ɛ″ was interpreted by the theory of dielectric relaxation due to interfacial polarization. It is also observed that ac electrical conductivity ( σ ac) and electric modulus ( M' and M″) increase with increasing frequency.

Transparent back contacts for P3HT:PCBM bulk heterojunction solar cells

International Nuclear Information System (INIS)

Sendova-Vassileva, M; Dikov, H; Popkirov, G; Lazarova, E; Vitanov, P; Gancheva, V; Grancharov, G; Tsocheva, D; Mokreva, P

2014-01-01

A new combination of layers functioning as a transparent contact is proposed and tested in real solar cells. The contacts consist of TiO 2 layers and thin metal layers (Ag, Cu) and are deposited by magnetron sputtering. The optical transmission and electrical conductivity of the transparent contact layers (TCL) are measured. The TCLs are applied as back contacts in bulk heterojunction polymer solar cells deposited on ITO covered glass and consisting of the following layers: ITO/PEDOT:PSS/P3HT:PCBM/back contact. The organic layers are deposited by spin-coating. For comparison, the same bulk heterojunction polymer solar cells are prepared with a sputtered Ag back contact. The first results show a dependence of the current-voltage parameters of the studied solar cells on the thickness of the different component layers of the transparent back contacts. There is a balance that has to be observed between the electrical characteristics of the contacts and their optical transparency. Future plans involve their inclusion as intermediate contacts in tandem organic solar cells.

Contribution of Hippocampal 5-HT3 Receptors in Hippocampal Autophagy and Extinction of Conditioned Fear Responses after a Single Prolonged Stress Exposure in Rats.

Science.gov (United States)

Wu, Zhong-Min; Yang, Li-Hua; Cui, Rong; Ni, Gui-Lian; Wu, Feng-Tian; Liang, Yong

2017-05-01

One of the hypotheses about the pathogenesis of posttraumatic stress disorder (PTSD) is the dysfunction of serotonin (5-HT) neurotransmission. While certain 5-HT receptor subtypes are likely critical for the symptoms of PTSD, few studies have examined the role of 5-HT 3 receptor in the development of PTSD, even though 5-HT 3 receptor is critical for contextual fear extinction and anxiety-like behavior. Therefore, we hypothesized that stimulation of 5-HT 3 receptor in the dorsal hippocampus (DH) could prevent hippocampal autophagy and the development of PTSD-like behavior in animals. To this end, we infused SR57227, selective 5-HT 3 agonist, into the DH after a single prolonged stress (SPS) treatment in rats. Three weeks later, we evaluated the effects of this pharmacological treatment on anxiety-related behaviors and extinction of contextual fear memory. We also accessed hippocampal autophagy and the expression of 5-HT 3A subunit, Beclin-1, LC3-I, and LC3-II in the DH. We found that SPS treatment did not alter anxiety-related behaviors but prolonged the extinction of contextual fear memory, and such a behavioral phenomenon was correlated with increased hippocampal autophagy, decreased 5-HT 3A expression, and increased expression of Beclin-1 and LC3-II/LC3-I ratio in the DH. Furthermore, intraDH infusions of SR57227 dose-dependently promoted the extinction of contextual fear memory, prevented hippocampal autophagy, and decreased expression of Beclin-1 and LC3-II/LC3-I ratio in the DH. These results indicated that 5-HT 3 receptor in the hippocampus may play a critical role in the pathogenesis of hippocampal autophagy, and is likely involved in the pathophysiology of PTSD.

Multi-wavelength investigations on feedback of massive star formation

Science.gov (United States)

Yuan, Jinghua

2014-05-01

In the course of massive star formation, outflows, ionizing radiation and intense stellar winds could heavily affect their adjacent environs and natal clouds. There are several outstanding open questions related to these processes: i) whether they can drive turbulence in molecular clouds; ii) whether they are able to trigger star formation; iii) whether they can destroy natal clouds to terminate star formation at low efficiencies. This thesis investigates feedback in different stages of massive star formation. Influence of such feedback to the ambient medium has been revealed. A new type of millimeter methanol maser is detected for the first time. An uncommon bipolar outflow prominent in the mid-infrared is discovered. And features of triggered star formation are found on the border of an infrared bubble and in the surroundings of a Herbig Be star. Extended green objects (EGOs) are massive outflow candidates showing prominent shocked features in the mid-infrared. We have carried out a high resolution study of the EGO G22.04+0.22 (hereafter, G22) based on archived SMA data. Continuum and molecular lines at 1.3 mm reveal that G22 is still at a hot molecular core stage. A very young multi-polar outflow system is detected, which is interacting with the adjacent dense gas. Anomalous emission features from CH3OH (8,-1,8 - 7,0,7) and CH3OH (4,2,2 - 3,1,2) are proven to be millimeter masers. It is the first time that maser emission of CH3OH (8,-1,8 - 7,0,7) at 218.440 GHz is detected in a massive star-forming region. Bipolar outflows have been revealed and investigated almost always in the microwave or radio domain. It's sort of rare that hourglass-shaped morphology be discovered in the mid-infrared. Based on GLIMPSE data, we have discovered a bipolar object resembling an hourglass at 8.0 um. It is found to be associated with IRAS 18114-1825. Analysis based on fitted SED, optical spectroscopy, and infrared color indices suggests IRAS 18114-1825 is an uncommon bipolar

Fundamental Study on the Effect of Spray Parameters on Characteristics of P3HT:PCBM Active Layers Made by Spray Coating

Directory of Open Access Journals (Sweden)

Yu Xie

2015-08-01

Full Text Available This paper is an attempt to elucidate the effects of the important spray characteristics on the surface morphology and light absorbance of spray-on P3HT:PCBM thin-films, used as an active layer in polymer solar cells (PSCs. Spray coating or deposition is a viable scalable technique for the large-scale, fast, and low-cost fabrication of solution-processed solar cells, and has been widely used for device fabrication, although the fundamental understanding of the underlying and controlling parameters, such as spray characteristics, droplet dynamics, and surface wettability, is still limited, making the results on device fabrication not reproducible and unreliable. In this paper, following the conventional PSC architecture, a PEDOT:PSS layer is first spin-coated on glass substrates, followed by the deposition of P3HT:PCBM using an automatic ultrasonic spray coating system, with a movable nozzle tip, to mimic an industrial manufacturing process. To gain insight, the effects of the spray carrier air pressure, the number of spray passes, the precursor flow rate, and precursor concentration are studied on the surface topography and light absorbance spectra of the spray-on films. Among the results, it is found that despite the high roughness of spray-on films, the light absorbance of the film is satisfactory. It is also found that the absorbance of spray-on films is a linear function of the number of spray passes or deposition layers, based on which an effective film thickness is defined for rough spray-on films. The effective thickness of a rough spray-on P3HT:PCBM film was found to be one-quarter of that of a flat film predicted by a simple mass balance.

THE OCCURRENCE RATE OF EARTH ANALOG PLANETS ORBITING SUN-LIKE STARS

International Nuclear Information System (INIS)

Catanzarite, Joseph; Shao, Michael

2011-01-01

Kepler is a space telescope that searches Sun-like stars for planets. Its major goal is to determine η Earth , the fraction of Sun-like stars that have planets like Earth. When a planet 'transits' or moves in front of a star, Kepler can measure the concomitant dimming of the starlight. From analysis of the first four months of those measurements for over 150,000 stars, Kepler's Science Team has determined sizes, surface temperatures, orbit sizes, and periods for over a thousand new planet candidates. In this paper, we characterize the period probability distribution function of the super-Earth and Neptune planet candidates with periods up to 132 days, and find three distinct period regimes. For candidates with periods below 3 days, the density increases sharply with increasing period; for periods between 3 and 30 days, the density rises more gradually with increasing period, and for periods longer than 30 days, the density drops gradually with increasing period. We estimate that 1%-3% of stars like the Sun are expected to have Earth analog planets, based on the Kepler data release of 2011 February. This estimate of η Earth is based on extrapolation from a fiducial subsample of the Kepler planet candidates that we chose to be nominally 'complete' (i.e., no missed detections) to the realm of the Earth-like planets, by means of simple power-law models. The accuracy of the extrapolation will improve as more data from the Kepler mission are folded in. Accurate knowledge of η Earth is essential for the planning of future missions that will image and take spectra of Earth-like planets. Our result that Earths are relatively scarce means that a substantial effort will be needed to identify suitable target stars prior to these future missions.

Descending serotonergic facilitation mediated by spinal 5-HT3 receptors engages spinal rapamycin-sensitive pathways in the rat

Science.gov (United States)

Asante, Curtis O.; Dickenson, Anthony H.

2010-01-01

We have recently reported the importance of spinal rapamycin-sensitive pathways in maintaining persistent pain-like states. A descending facilitatory drive mediated through spinal 5-HT3 receptors (5-HT3Rs) originating from superficial dorsal horn NK1-expressing neurons and that relays through the parabrachial nucleus and the rostroventral medial medulla to act on deep dorsal horn neurons is known be important in maintaining these pain-like states. To determine if spinal rapamycin-sensitive pathways are activated by a descending serotonergic drive, we investigated the effects of spinally administered rapamycin on responses of deep dorsal horn neurons that had been pre-treated with the selective 5-HT3R antagonist ondansetron. We also investigated the effects of spinally administered cell cycle inhibitor (CCI)-779 (a rapamycin ester analogue) on deep dorsal horn neurons from rats with carrageenan-induced inflammation of the hind paw. Unlike some other models of persistent pain, this model does not involve an altered 5-HT3R-mediated descending serotonergic drive. We found that the inhibitory effects of rapamycin were significantly reduced for neuronal responses to mechanical and thermal stimuli when the spinal cord was pre-treated with ondansetron. Furthermore, CCI-779 was found to be ineffective in attenuating spinal neuronal responses to peripheral stimuli in carrageenan-treated rats. Therefore, we conclude that 5-HT3R-mediated descending facilitation is one requirement for activation of rapamycin-sensitive pathways that contribute to persistent pain-like states. PMID:20709148

A comparison of the effects on central 5-HT function of sibutramine hydrochloride and other weight-modifying agents

Science.gov (United States)

Heal, D J; Cheetham, S C; Prow, M R; Martin, K F; Buckett, W R

1998-01-01

Effects on 5-HT function of sibutramine and its active metabolites, BTS 54 354 and BTS 54 505, were compared with fluoxetine, (+)-fenfluramine and (+)-amphetamine.In vitro sibutramine weakly inhibited [3H]-5-HT uptake into brain synaptosomes. BTS 54 354, BTS 54 505 and fluoxetine were powerful [3H]-5-HT uptake inhibitors, whereas (+)-fenfluramine and (+)-amphetamine were very much weaker. Conversely, whilst sibutramine, its metabolites and fluoxetine did not release [3H]-5-HT from brain slices at ⩽10−5M, (+)-fenfluramine and (+)-amphetamine concentration-dependently increased [3H]-5-HT release.Sibutramine and fluoxetine had no effect on 5-hydroxytryptophan (5-HTP) accumulation in either frontal cortex or hypothalamus at doses Sibutramine (10 mg kg−1 i.p.) and fluoxetine (10 mg kg−1 i.p.) produced slow, prolonged increases of extracellular 5-HT in the anterior hypothalamus. In contrast, (+)-fenfluramine (3 mg kg−1 i.p.) and (+)-amphetamine (4 mg kg−1 i.p.) induced rapid, short-lasting increases in extracellular 5-HT.Only (+)-fenfluramine (10 mg kg−1) altered 5-HT2A receptors in rat frontal cortex when given for 14 days, producing a 61% reduction in receptor number and a 18% decrease in radioligand affinity.These results show that sibutramine powerfully enhances central 5-HT function via its secondary and primary amine metabolites; this effect, like that of fluoxetine, is almost certainly mediated through 5-HT uptake inhibition. By contrast, (+)-fenfluramine enhances 5-HT function predominantly by increasing 5-HT release. (+)-Amphetamine, though weaker than (+)-fenfluramine, also enhances 5-HT function by release. PMID:9786502

Prospective, Multi-Centre, Single-Arm Study of Mechanical Thrombectomy using Solitaire FR in Acute Ischemic Stroke-STAR

Science.gov (United States)

Pereira, Vitor M; Gralla, Jan; Davalos, Antoni; Bonafé, Alain; Castaño, Carlos; Chapot, Rene; Liebeskind, David S; Nogueira, Raul G; Arnold, Marcel; Sztajzel, Roman; Liebig, Thomas; Goyal, Mayank; Besselmann, Michael; Moreno, Alfredo; Schroth, Gerhard

2013-01-01

Background and Purpose Mechanical thrombectomy using stent retriever devices have been advocated to increase revascularization in intracranial vessel occlusion. We present the results of a large prospective study on the use of the Solitaire FR in patients with acute ischemic stroke. Methods STAR was an international, multicenter, prospective, single-arm study of Solitaire FR thrombectomy in patients with large vessel anterior circulation strokes treated within 8 hours of symptom onset. Strict criteria for site selection were applied. The primary endpoint was the revascularization rate (3TICI 2b) of the occluded vessel as determined by an independent core lab. The secondary endpoint was the rate of good functional outcome (defined as 90-day modified Rankin scale (mRS) 0–2). Results A total of 202 patients were enrolled across 14 comprehensive stroke centers in Europe, Canada and Australia. The median age was 72 years, 60% were female patients. The median National Institute of Health Stroke Scale (NIHSS) was 17. Most proximal intracranial occlusion was the internal carotid artery in 18%, the middle cerebral artery in 82%. Successful revascularization was achieved in 79.2% of patients. Device and/or procedure related severe adverse events were found in 7.4%. Favorable neurological outcome was found in 57.9%. The mortality rate was 6.9%. Any intracranial hemorrhagic transformation was found in 18.8% of patients, 1.5% were symptomatic. Conclusions In this single arm study, treatment with the Solitaire™ FR device in intracranial anterior circulation occlusions results in high rates of revascularization, low risk of clinically relevant procedural complications, and good clinical outcomes in combination with low mortality at 90 days. Clinical Trial Registration This study is registered with ClinicalTrials.gov, number NCT01327989. PMID:23908066

Energy-Crossing and Its Effect on Lifetime of the 4s24p 2P3/2 Level for Highly Charged Ga-Like Ions

International Nuclear Information System (INIS)

Fan Jian-Zhong; Zhang Deng-Hong; Chang Zhi-Wei; Shi Ying-Long; Dong Chen-Zhong

2012-01-01

The multi-configuration Dirac—Fock method is employed to calculate the energy levels and transition probabilities for the electric dipole allowed (E1) and forbidden (M1, E2) lines for the 4s 2 4p, 4s4p 2 and 4s 2 4d configurations of highly charged Ga-like ions from Z = 68–95. The lifetimes of the 4s 2 4p 2 P 3/2 level of the ground configuration are also derived. Based on our calculations, it is found that the energy level of the 4s 2 4p 2 P 3/2 is higher than that of the 4s4p 2 4 P 1/2 for the high-Z Ga-like ions with Z ≥ 74, so as to generate an energy crossing at Z = 74. The effect of the energy crossing is important to the calculation of the 4s 2 4p 2 P 3/2 level lifetime for Ga-like ions with Z ≥ 74. (atomic and molecular physics)

Simultaneous, multi-wavelength flare observations of nearby low-mass stars

Science.gov (United States)

Thackeray, Beverly; Barclay, Thomas; Quintana, Elisa; Villadsen, Jacqueline; Wofford, Alia; Schlieder, Joshua; Boyd, Patricia

2018-01-01

Low-mass stars are the most common stars in the Galaxy and have been targeted in the tens-of-thousands by K2, the re-purposed Kepler mission, as they are prime targets to search for and characterize small, Earth-like planets. Understanding how these fully convective stars drive magnetic activity that manifests as stochastic, short-term brightenings, or flares, provides insight into the prospects of planetary habitability. High energy radiation and energetic particle emission associated with these stars can erode atmospheres, and impact habitability. An innovative campaign to study low mass stars through simultaneous multi-wavelength observations is currently underway with observations ongoing in the X-ray, UV, optical, and radio. I will present early results of our pilot study of the nearby M-Dwarf star Wolf 359 (CN Leo) using K2, SWIFT, and ground based radio observatories, forming a comprehensive picture of flare activity from an M-Dwarf, and discuss the potential impact of these results on exoplanets. "This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE1322106. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation."

Structural properties of star-like dendrimers in solution

International Nuclear Information System (INIS)

Rathgeber, S.; Gast, A.P.; Hedrick, J.L.

2002-01-01

We measured the form factor of star-like poly-ε-caprolactone dendrimers under good solvent conditions with small-angle neutron scattering (SANS). The parameters varied in the experiment were the dendrimer generation g=1,2,3 and the number of segments between the branching units n=5,10,15,20. The results are discussed in the frame work of the Beaucage model from which we cannot only derive the radius of gyration R g of the dendrimers but also their fractal dimensions. Decreasing the number of spacer units between the branching points results in a strong stretching of the dendrons. The fractal dimension increases monotonically with increasing generation and spacer number between the limit expected for a low-functionality star P∼5/3 (loose, polymeric structure) and that expected for a high-functionality star P∼3 (compact shape). (orig.)

Serotonin 5-HT3 and 5-HT4 ligands: an update of medicinal chemistry research in the last few years.

Science.gov (United States)

Modica, M N; Pittalà, V; Romeo, G; Salerno, L; Siracusa, M A

2010-01-01

The biogenic amine serotonin (5-hydroxytryptamine, 5-HT) is one of the most studied neurotransmitters in the central nervous system. It acts through the activation of at least fourteen 5-HT receptor subtypes. Over the last two decades, high attention was devoted to the 5-HT(3) and 5-HT(4) receptors due to their colocalization in the gastrointestinal tract and because their ligands are useful in the treatment of intestinal serotonergic system dysfunctions. The focus of this review is to discuss the literature concerning recent advances on 5-HT(3)R and 5-HT(4)R ligands and their structure-activity relationships from a medicinal chemistry perspective. During the last few years, new and significant progresses have been made in the field of novel potent and selective ligands, mixed ligands, agonists, partial agonists, and antagonists, and a number of patents have been filed. Furthermore several ligands targeting the 5-HT(3)R and 5-HT(4)R have been proposed for novel therapeutic indications such as the treatment of various psychiatric disorders.

Stellar complexes in spiral arms of galaxies

Science.gov (United States)

Efremov, Yu. N.

The history of the introduction and development of the star complexes conception is briefly described. These large groups of stars were picked out and named as such ones in our Galaxy with argumentation and evidence for their physical unity (using the Cepheid variables the distances and ages of which are easy determined from their periods); anyway earlier the complexes were noted along the spiral arms of the Andromeda galaxy, but were not recognized as a new kind of star group. The chains of complexes along the spiral arms are observed quite rarely; their origin is explained by magneto- gravitational or purely gravitational instability developing along the arm. It is not clear why these chains are quite a rare phenomenon - and more so why sometimes the regular chain of complexes are observed in one arm only. Probably intergalactic magnetic field participated in formation of such chains. Apart from the complexes located along the arms, there are isolated giant complexes known (up to 700 pc in diameter) which look like super-gigantic but rather rarefied globular clusters. Until now only two of these formations are studied, in NGC 6946 and M51.

Single-molecule imaging reveals topological isomer-dependent diffusion by 4-armed star and dicyclic 8-shaped polymers

KAUST Repository

Habuchi, Satoshi

2015-04-21

Diffusion dynamics of topological isomers of polymer molecules was investigated at the single-molecule level in a melt state by employing the fluorophore-incorporated 4-armed star and the corresponding doubly-cyclized, 8-shaped poly(THF) chains. While the single-molecule fluorescence imaging experiment revealed that the diffusion of the 4-armed star polymer was described by a single Gaussian distribution, the diffusion of the 8-shaped polymer exhibited a double Gaussian distribution behaviour. We reasoned that the two 8-shaped polymeric isomers have distinct diffusion modes in the melt state, although ensemble-averaged experimental methods cannot detect differences in overall conformational state of the isomers. The single-molecule experiments suggested that one of the 8-shaped polymeric isomer, having the horizontally oriented form, causes an efficient threading with the linear matrix chains which leads to the slower diffusion compared with the corresponding 4-armed star polymer, while the other 8-shaped polymeric isomer, having the vertically oriented form, displayed faster diffusion by the suppression of effective threading with the linear matrix chains due to its contracted chain conformation.

Constitutional Isomers of Dendrimer-like Star Polymers: Design, Synthesis and Conformational and Structural Properties; TOPICAL

International Nuclear Information System (INIS)

Pople, John A.

2001-01-01

The design, synthesis and solution properties of six constitutional isomers of dendrimer-like star polymers is described. Each of the polymers have comparable molecular weights ((approx) 80,000 g/mol), narrow polydispersities ( and lt; 1.19) and an identical number of branching junctures (45) and surface hydroxyl functionalities (48). The only difference in the six isomers is the placement of the branching junctures. The polymers are constructed from high molecular weight poly(e-caprolactone) with branching junctures derived from 2,2'-bis(hydroxylmethyl) propionic acid (bis-MPA) emanating from a central core. The use of various generations of dendritic initiators and dendrons coupled with the ring opening polymerization of e-caprolactones allowed a modular approach to the dendrimer-like star polymer isomers. The most pronounced effects on the physical properties/morphology and hydrodynamic volume was for those polymers in which the branching was distributed throughout the sample in a dendrimer-like fashion. The versatility of this approach has provided the possibility of understanding the relationship between architecture and physical properties. Dynamic light scattering and small angle X-ray scattering techniques were used to determine the hydrodynamic radius Rh and radius of gyration Rg respectively. The relationship between Rg and molecular weight was indicative of a compact star-like structure, and did not show advanced bias towards either the dense core or dense shell models. The radial density distribution of the isomers was therefore modeled according to a many arm star polymer, and good agreement was found with experimental measures of Rh/Rg

Electrical and optical modeling of poly(3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester P3HT-PCBM bulk heterojunction solar cells

Science.gov (United States)

Brioua, Fathi; Remram, Mohamed; Nechache, Riad; Bourouina, Hicham

2017-11-01

In this work, we investigate a two-dimensional theoretical model for the photon conversion through an integration of the optical and electrical part of multilayer system in a bulk heterojunction solar cell based on poly(3-hexylthiophene) (P3HT)/6,6-phenyl C61-butyric acid methyl ester (PCBM) blend. The optical properties of the studied structure ITO/PEDOT:PSS/P3HT:PCBM/Ca/Al, such as the exciton generation rate and the electrical field distribution, are predicted at vicinity of the active layer and have been used to solve Poisson and continuity, drift-diffusion equations of the electrical model which characterize the electrical behavior of semiconductor device using finite element method (FEM). The electrical parameters such as power conversion efficiency (PCE), open voltage circuit ( V oc), short-circuit current density ( J sc) and fill factor (FF) are extracted from the current-voltage (J-V) characteristics under illumination and in dark conditions. Highest external quantum efficiency (IPCE), up to 60%, is obtained around 520 nm, while a power conversion efficiency (PCE) value of 3.62% is found to be in good agreement with the literature results. Integration of such theoretical approach into technological applications dealing with optoelectrical material performance will rapidly provide to the user accurate data outputs required for efficient validation of proof-of-concepts.

Three Arm Star Homo- And Co-Polymers Via Atom Transfer Radical Polymerization

International Nuclear Information System (INIS)

Amin, A.; Sobh, R.A.; Ayoub, M.M.H.

2005-01-01

Star homo and co-polymers of some vinyl monomers such as methylmethacrylate, butylmethacrylate and styrene (MMA, BMA, St.) were prepared using N, N, N', N' tetramethylethylenediamine ligand/ CuBr catalytic system via atom transfer radical polymerization (ATRP). Three armed benzene based core was successfully used as initiator. Low polydispersities and regular molecular weight values were obtained in most cases especially at low conversions. MMA and BuMA showed comparable behavior where controlled and true ATRP was observed even at the high conversions. However, styrene monomer recorded irregular high polydispersities at high conversions in spite of the relatively low molecular weight values. 1HNMR confirmed the structures of the resulting polymers. Transmission Electron microscope (TEM) proved the nano-structure of the star polymers. The thermal behavior of the MMA star homo and copolymers was studied. The effect of the star shape on the thermal behavior was very clear with respect to the linear ones

Potential effect of CuInS2/ZnS core-shell quantum dots on P3HT/PEDOT:PSS heterostructure based solar cell

Science.gov (United States)

Jindal, Shikha; Giripunje, S. M.

2018-07-01

Nanostructured quantum dots (QDs) are quite promising in the solar cell application due to quantum confinement effect. QDs possess multiple exciton generation and large surface area. The environment friendly CuInS2/ZnS core-shell QDs were prepared by solvothermal method. Thus, the 3 nm average sized CuInS2/ZnS QDs were employed in the bulk heterojunction device and the active blend layer consisting of the P3HT and CuInS2/ZnS QDs was investigated. The energy level information of CuInS2/ZnS QDs as an electron acceptor was explored by ultra violet photoelectron spectroscopy. Bulk heterojunction hybrid device of ITO/PEDOT:PSS/P3HT: (CuInS2/ZnS QDs)/ZnO/Ag was designed by spin coating approach and its electrical characterization was investigated by solar simulator. Current density - voltage characteristics shows the enhancement in power conversion efficiency with increasing concentration of CuInS2/ZnS QDs in bulk heterojunction device.

Fabrication of Hybrid Polymer Solar Cells By Inverted Structure Based on P3HT:PCBM Active Layer

Directory of Open Access Journals (Sweden)

Shobih Shobih

2017-08-01

Full Text Available Hybrid polymer solar cell has privilege than its conventional structure, where it usually has structure of (ITO/PEDOT:PSS/Active Layer/Al. In humid environment the PEDOT:PSS will absorb water and hence can easily etch the ITO. Therefore it is necessary to use an alternative method to avoid this drawback and obtain more stable polymer solar cells, namely by using hybrid polymer solar cells structure with an inverted device architecture from the conventional, by reversing the nature of charge collection. In this paper we report the results of the fabrication of inverted bulk heterojunction polymer solar cells based on P3HT:PCBM as active layer, utilizing ZnO interlayer as buffer layer between the ITO and active layer with a stacked structure of ITO/ZnO/P3HT:PCBM/PEDOT:PSS/Ag. The ZnO interlayer is formed through short route, i.e. by dissolving ZnO nanoparticles powder in chloroform-methanol solvent blend rather than by sol-gel process. Based on the measurement results on electrical characteristics of inverted polymer solar cells under 500 W/m2 illumination and AM 1.5 direct filter at room temperature, cell with annealing process of active layer at 110 °C for 10 minutes results in higher cell performance than without annealing, with an open-circuit voltage of 0.21 volt, a short-circuit current density of 1.33 mA/cm2 , a fill factor of 43.1%, and a power conversion efficiency of 0.22%. The low cell’s performance is caused by very rough surface of ZnO interlayer.

Interstitial deletion of the short arm of chromosome 3. Fetal pathology and exclusion of the gene for beta-galactosidase-1 (GLB-1) from 3(p11----p14.2)

DEFF Research Database (Denmark)

Hertz, Jens Michael; Coerdt, W; Hahnemann, N

1988-01-01

A de novo interstitial deletion of the short arm of chromosome 3 was prenatally diagnosed in a male fetus, karyotype 46,XY,del(3)(pter----p14.2::p11----qter). The fetus had craniofacial dysmorphisms, a single transverse palmar crease, ulnar deviation in the wrists, cardiovascular anomalies...

Involvement of N-methyl-d-aspartate receptors in the antidepressant-like effect of 5-hydroxytryptamine 3 antagonists in mouse forced swimming test and tail suspension test.

Science.gov (United States)

Kordjazy, Nastaran; Haj-Mirzaian, Arya; Amiri, Shayan; Ostadhadi, Sattar; Amini-Khoei, Hossein; Dehpour, Ahmad Reza

2016-02-01

Recent evidence indicates that 5-hydroxytryptamine 3 (5-HT3) antagonists such as ondansetron and tropisetron exert positive behavioral effects in animal models of depression. Due to the ionotropic nature of 5-HT3 and N-methyl-d-aspartate (NMDA) receptors, plus their contribution to the pathophysiology of depression, we investigated the possible role of NMDA receptors in the antidepressant-like effect of 5-HT3 receptor antagonists in male mice. In order to evaluate the animals' behavior in response to different treatments, we performed open-field test (OFT), forced swimming test (FST), and tail-suspension test (TST), which are considered as valid tasks for measuring locomotor activity and depressive-like behaviors in mice. Our data revealed that intraperitoneal (i.p.) administration of tropisetron (5, 10, and 30mg/kg) and ondansetron (0.01, and 0.1μg/kg) significantly decreased the immobility time in FST and TST. Also, co-administration of subeffective doses of tropisetron (1mg/kg, i.p.) or ondansetron (0.001μg/kg, i.p.) with subeffective doses of NMDA receptor antagonists, ketamine (1mg/kg, i.p.), MK-801 (0.05mg/kg, i.p.) and magnesium sulfate (10mg/kg, i.p.) resulted in a reduced immobility time both in FST and TST. The subeffective dose of NMDA (NMDA receptor agonist, 75mg/kg, i.p.) abolished the effects of 5-HT3 antagonists in FST and TST, further supporting the presumed interaction between 5-HT3 and NMDA receptors. These treatments did not affect the locomotor behavior of animals in OFT. Finally, the results of our study suggest that the positive effects of 5-HT3 antagonists on the coping behavior of mice in FST and TST are at least partly mediated through NMDA receptors participation. Copyright © 2015 Elsevier Inc. All rights reserved.

Successful treatment with risperidone increases 5-HT 3A receptor gene expression in patients with paranoid schizophrenia - data from a prospective study.

Science.gov (United States)

Chen, Hongying; Fan, Yong; Zhao, Lei; Hao, Yong; Zhou, Xiajun; Guan, Yangtai; Li, Zezhi

2017-09-01

The relationship between peripheral 5-HT3A receptor mRNA level and risperidone efficiency in paranoid schizophrenia patients is still unknown. A total 52 first-episode and drug-naive paranoid schizophrenia patients who were treated with risperidone and 53 matched healthy controls were enrolled. Patients were naturalistically followed up for 8 weeks. Positive and Negative Syndrome Scale (PANSS) was applied to assess symptom severity of the patients at baseline and at the end of 8th week. There was no difference in 5-HT3A receptor mRNA level between paranoid schizophrenia patients and healthy controls at baseline ( p  = .24). Among 47 patients who completed 8-week naturalistic follow-up, 37 were responders to risperidone treatment. 5-HT3A receptor mRNA level of paranoid schizophrenia patients did not change in overall patients after 8-week treatment with risperidone ( p  = .29). However, 5-HT3A receptor mRNA level in responders increased significantly ( p  = .04), but not in nonresponders ( p  = .81). Successful treatment with risperidone increases 5-HT3A receptor gene expression in patients with paranoid schizophrenia, indicating that 5-HT3A receptor may be involved in the mechanism of risperidone effect.

Multi-Wavelength Polarimetry of Isolated Neutron Stars

Directory of Open Access Journals (Sweden)

Roberto P. Mignani

2018-03-01

Full Text Available Isolated neutron stars are known to be endowed with extreme magnetic fields, whose maximum intensity ranges from 10 12 – 10 15 G, which permeates their magnetospheres. Their surrounding environment is also strongly magnetized, especially in the compact nebulae powered by the relativistic wind from young neutron stars. The radiation from isolated neutron stars and their surrounding nebulae is, thus, supposed to bring a strong polarization signature. Measuring the neutron star polarization brings important information about the properties of their magnetosphere and of their highly magnetized environment. Being the most numerous class of isolated neutron stars, polarization measurements have been traditionally carried out for radio pulsars, hence in the radio band. In this review, I summarize multi-wavelength linear polarization measurements obtained at wavelengths other than radio both for pulsars and other types of isolated neutron stars and outline future perspectives with the upcoming observing facilities.

Super-Eddington accretion on to the neutron star NGC 7793 P13: Broad-band X-ray spectroscopy and ultraluminous X-ray sources

Science.gov (United States)

Walton, D. J.; Fürst, F.; Harrison, F. A.; Stern, D.; Bachetti, M.; Barret, D.; Brightman, M.; Fabian, A. C.; Middleton, M. J.; Ptak, A.; Tao, L.

2018-02-01

We present a detailed, broad-band X-ray spectral analysis of the ultraluminous X-ray source (ULX) pulsar NGC 7793 P13, a known super-Eddington source, utilizing data from the XMM-Newton, NuSTAR and Chandra observatories. The broad-band XMM-Newton+NuSTAR spectrum of P13 is qualitatively similar to the rest of the ULX sample with broad-band coverage, suggesting that additional ULXs in the known population may host neutron star accretors. Through time-averaged, phase-resolved and multi-epoch studies, we find that two non-pulsed thermal blackbody components with temperatures ∼0.5 and 1.5 keV are required to fit the data below 10 keV, in addition to a third continuum component which extends to higher energies and is associated with the pulsed emission from the accretion column. The characteristic radii of the thermal components appear to be comparable, and are too large to be associated with the neutron star itself, so the need for two components likely indicates the accretion flow outside the magnetosphere is complex. We suggest a scenario in which the thick inner disc expected for super-Eddington accretion begins to form, but is terminated by the neutron star's magnetic field soon after its onset, implying a limit of B ≲ 6 × 1012 G for the dipolar component of the central neutron star's magnetic field. Evidence of similar termination of the disc in other sources may offer a further means of identifying additional neutron star ULXs. Finally, we examine the spectrum exhibited by P13 during one of its unusual 'off' states. These data require both a hard power-law component, suggesting residual accretion on to the neutron star, and emission from a thermal plasma, which we argue is likely associated with the P13 system.

Impaired social behavior in 5-HT3A receptor knockout mice

Directory of Open Access Journals (Sweden)

Laura A Smit-Rigter

2010-11-01

Full Text Available The 5-HT3 receptor is a ligand-gated ion channel expressed on interneurons throughout the brain. So far, analysis of the 5-HT3A knockout mouse revealed changes in nociceptive processing and a reduction in anxiety related behavior. Recently, it was shown that the 5-HT3 receptor is also expressed on Cajal-Retzius cells which play a key role in cortical development and that knockout mice lacking this receptor showed aberrant growth of the dendritic tree of cortical layer II/III pyramidal neurons. Other mouse models in which serotonergic signaling was disrupted during development showed similar morphological changes in the cortex, and in addition, also deficits in social behavior. Here, we subjected male and female 5-HT3A knockout mice and their non-transgenic littermates to several tests of social behavior. We found that 5-HT3A knockout mice display impaired social communication in the social transmission of food preference task. Interestingly, we showed that in the social interaction test only female 5-HT3A knockout mice spent less time in reciprocal social interaction starting after 5 minutes of testing. Moreover, we observed differences in preference for social novelty for male and female 5-HT3A knockout mice during the social approach test. However, no changes in olfaction, exploratory activity and anxiety were detected. These results indicate that the 5-HT3A knockout mouse displays impaired social behavior with specific changes in males and females, reminiscent to other mouse models in which serotonergic signaling is disturbed in the developing brain.

Isoelectronic comparison of the Al-like 3s23p 2P-3s3p24P transitions in the ions P III-Mo XXX

International Nuclear Information System (INIS)

Jupen, C.; Curtis, L.J.

1996-01-01

New observations of the 3s 2 3p 2 P-3s3p 2 4 P intercombination transitions in Al-like ions have been made for Cl V from spark spectra recorded at Lund and for Kr XXIV and Mo XXX from spectra obtained at the JET tokamak. The new results have been combined with other identifications of these transitions along the sequence and empirically systematized and compared with theoretical calculations. A set of smoothed and interpolated values for the excitation energies of the 3s3p 2 4 P levels in P III-Mo XXX is presented. (orig.)

Phosphotidylinositol turnover in vascular, uterine, fundal, and tracheal smooth muscle: effect of serotonin (5HT)

International Nuclear Information System (INIS)

Cohen, M.L.; Wittenauer, L.A.

1986-01-01

In brain, platelets, and aorta, 5HT has been reported to increase phosphotidylinositol turnover, an effect linked to 5HT 2 receptors. The authors examined the effect of 5HT on 3 H-inositol-1-phosphate ( 3 H-I-P) in tissues possessing 5HT 2 receptors that mediate contraction to 5HT (rat jugular vein, aorta, uterus and guinea pig trachea) and in a tissue in which contraction to 5HT is not mediated by 5HT 2 receptors (rat stomach fundus). Tissues were incubated (37 0 C, 95% O 2 , 5% CO 2 ) with 3 H-inositol (90 min), washed, LiCl 2 (10 mM) and 5HT added for 90 min, extracted, and 3 H-I-P eluted from a Dowex-1 column. Basal 3 H-I-P was 10-fold higher in the uterus than in the other tissues. 5HT (10 -6 -10 -4 M) increased 3 H-I-P in the jugular vein, aorta, and uterus but not in the trachea or fundus. Maximum increase was greatest in the jugular vein (8-fold) with an ED 50 of 0.4 μM 5HT. The selective 5HT 2 receptor blocker, LY53857 (10 -8 M) antagonized the increase in 3 H-I-P by 5HT in the jugular vein, aorta and uterus. Pargyline (10 -5 M) added to the trachea and fundus did not unmask an effect of 5HT (10 -4 M). These data suggest that (1) the jugular vein produced the most sensitive response to 5HT-induced increases in 3 H-I-P, (2) increases in 3 H-I-P by 5HT in smooth muscle may be linked to 5HT 2 receptors and (3) activation of 5HT 2 receptors as occurred in the trachea will not always increase 3 H-I-P

Machine-learned Identification of RR Lyrae Stars from Sparse, Multi-band Data: The PS1 Sample

Science.gov (United States)

Sesar, Branimir; Hernitschek, Nina; Mitrović, Sandra; Ivezić, Željko; Rix, Hans-Walter; Cohen, Judith G.; Bernard, Edouard J.; Grebel, Eva K.; Martin, Nicolas F.; Schlafly, Edward F.; Burgett, William S.; Draper, Peter W.; Flewelling, Heather; Kaiser, Nick; Kudritzki, Rolf P.; Magnier, Eugene A.; Metcalfe, Nigel; Tonry, John L.; Waters, Christopher

2017-05-01

RR Lyrae stars may be the best practical tracers of Galactic halo (sub-)structure and kinematics. The PanSTARRS1 (PS1) 3π survey offers multi-band, multi-epoch, precise photometry across much of the sky, but a robust identification of RR Lyrae stars in this data set poses a challenge, given PS1's sparse, asynchronous multi-band light curves (≲ 12 epochs in each of five bands, taken over a 4.5 year period). We present a novel template fitting technique that uses well-defined and physically motivated multi-band light curves of RR Lyrae stars, and demonstrate that we get accurate period estimates, precise to 2 s in > 80 % of cases. We augment these light-curve fits with other features from photometric time-series and provide them to progressively more detailed machine-learned classification models. From these models, we are able to select the widest (three-fourths of the sky) and deepest (reaching 120 kpc) sample of RR Lyrae stars to date. The PS1 sample of ˜45,000 RRab stars is pure (90%) and complete (80% at 80 kpc) at high galactic latitudes. It also provides distances that are precise to 3%, measured with newly derived period-luminosity relations for optical/near-infrared PS1 bands. With the addition of proper motions from Gaia and radial velocity measurements from multi-object spectroscopic surveys, we expect the PS1 sample of RR Lyrae stars to become the premier source for studying the structure, kinematics, and the gravitational potential of the Galactic halo. The techniques presented in this study should translate well to other sparse, multi-band data sets, such as those produced by the Dark Energy Survey and the upcoming Large Synoptic Survey Telescope Galactic plane sub-survey.

Effect of oligonucleic acid (ONA) backbone features on assembly of ONA-star polymer conjugates: a coarse-grained molecular simulation study.

Science.gov (United States)

Condon, Joshua E; Jayaraman, Arthi

2017-10-04

Understanding the impact of incorporating new physical and chemical features in oligomeric DNA mimics, termed generally as "oligonucleic acids" (ONAs), on their structure and thermodynamics will be beneficial in designing novel materials for a variety of applications. In this work, we conduct coarse-grained molecular simulations of ONA-star polymer conjugates with varying ONA backbone flexibility, ONA backbone charge, and number of arms in the star polymer at a constant ONA strand volume fraction to elucidate the effect of these design parameters on the thermodynamics and assembly of multi-arm ONA-star polymer conjugates. We quantify the thermo-reversible behavior of the ONA-star polymer conjugates by quantifying the hybridization of the ONA strands in the system as a function of temperature (i.e. melting curve). Additionally, we characterize the assembly of the ONA-star polymer conjugates by tracking cluster formation and percolation as a function of temperature, as well as cluster size distribution at temperatures near the assembly transition region. The key results are as follows. The melting temperature (T m ) of the ONA strands decreases upon going from a neutral to a charged ONA backbone and upon increasing flexibility of the ONA backbone. Similar behavior is seen for the assembly transition temperature (T a ) with varying ONA backbone charge and flexibility. While the number of arms in the ONA-star polymer conjugate has a negligible effect on the ONA T m in these systems, as the number of ONA-star polymer arms increase, the assembly temperature T a increases and local ordering in the assembled state improves. By understanding how factors like ONA backbone charge, backbone flexibility, and ONA-star polymer conjugate architecture impact the behavior of ONA-star polymer conjugate systems, we can better inform how the selection of ONA chemistry will influence resulting ONA-star polymer assembly.

Abrogated Freud-1/Cc2d1a Repression of 5-HT1A Autoreceptors Induces Fluoxetine-Resistant Anxiety/Depression-Like Behavior.

Science.gov (United States)

Vahid-Ansari, Faranak; Daigle, Mireille; Manzini, M Chiara; Tanaka, Kenji F; Hen, René; Geddes, Sean D; Béïque, Jean-Claude; James, Jonathan; Merali, Zul; Albert, Paul R

2017-12-06

Freud-1/Cc2d1a represses the gene transcription of serotonin-1A (5-HT1A) autoreceptors, which negatively regulate 5-HT tone. To test the role of Freud-1 in vivo , we generated mice with adulthood conditional knock-out of Freud-1 in 5-HT neurons ( cF1ko ). In cF1ko mice, 5-HT1A autoreceptor protein, binding and hypothermia response were increased, with reduced 5-HT content and neuronal activity in the dorsal raphe. The cF1ko mice displayed increased anxiety- and depression-like behavior that was resistant to chronic antidepressant (fluoxetine) treatment. Using conditional Freud-1/5-HT1A double knock-out ( cF1/1A dko ) to disrupt both Freud-1 and 5-HT1A genes in 5-HT neurons, no increase in anxiety- or depression-like behavior was seen upon knock-out of Freud-1 on the 5-HT1A autoreceptor-negative background; rather, a reduction in depression-like behavior emerged. These studies implicate transcriptional dysregulation of 5-HT1A autoreceptors by the repressor Freud-1 in anxiety and depression and provide a clinically relevant genetic model of antidepressant resistance. Targeting specific transcription factors, such as Freud-1, to restore transcriptional balance may augment response to antidepressant treatment. SIGNIFICANCE STATEMENT Altered regulation of the 5-HT1A autoreceptor has been implicated in human anxiety, major depression, suicide, and resistance to antidepressants. This study uniquely identifies a single transcription factor, Freud-1, as crucial for 5-HT1A autoreceptor expression in vivo Disruption of Freud-1 in serotonin neurons in mice links upregulation of 5-HT1A autoreceptors to anxiety/depression-like behavior and provides a new model of antidepressant resistance. Treatment strategies to reestablish transcriptional regulation of 5-HT1A autoreceptors could provide a more robust and sustained antidepressant response. Copyright © 2017 the authors 0270-6474/17/3711967-12$15.00/0.

Molecular clouds in the Carina arm - the largest objects, associated regions of star formation, and the Carina arm in the Galaxy

International Nuclear Information System (INIS)

Grabelsky, D.A.; Cohen, R.S.; Bronfman, L.; Thaddeus, P.

1988-01-01

The Columbia CO survey of the southern Galactic plane is used to identify giant molecular clouds and cloud complexes in the Vela-Carina-Centaurus section of the Galaxy. Twenty-seven giant molecular clouds between l = 270 and 300 deg are catalogued and their heliocentric distances given. In addition, 16 clouds at l greater than 300 deg beyond the solar circle extend the catalog to include the very distant portion of the Carina arm. The most massive clouds in the catalog trace the Carina arm over 23 kpc in the plane of the Galaxy. The average mass of these objects is 1.4 x 10 to the 6th solar, and their average spacing along the arm is 700 pc. The composite distribution projected onto the Galactic plane of the largest molecular clouds in the Carina arm and of similarly massive clouds in the first and second quadrants strongly suggests that the Carina and Sagittarius arms form a single spiral arm about 40 kpc in length wrapping two-thirds of the way around the Galaxy. Descriptions of each cloud, including identification of associated star-forming regions, are presented in an appendix. 76 references

Fabrication and Optimization of Polymer Solar Cells Based on P3HT:PC70BM System

Directory of Open Access Journals (Sweden)

Huangzhong Yu

2016-01-01

Full Text Available Efficient bulk heterojunction (BHJ polymer solar cells (PSCs based on P3HT:PC70BM were fabricated by optimizing the processing parameters. The optimized thickness and annealing temperature have been found to be about 200 nm and 130°C. The effect of cathode interfacial layers on device performance is related to the formation of interfacial dipole. Furthermore, the effect of optimum ZnO interfacial thickness (~30 nm on device performance is attributed to good interfacial conductivity and its optical property. The metal electrode deposited in the slow rate has a better influence on device performance. Based on these optimal conditions, the best power conversion efficiency (PCE of 3.91% was obtained under AM 1.5G and 100 mW/cm2 illumination. This detailed investigation provides an important reference for the fabrication and optimization of polymer photovoltaic devices.

Characterization of the binding of 3H-norzimeldine, a 5-HT uptake inhibitor, to rat brain homogenates

International Nuclear Information System (INIS)

Hall, H.

1984-01-01

The binding of radiolabelled norzimeldine, a potent selective 5-HT reuptake inhibitor, to rat brain homogenates is described. 3 H-Norzimeldine binds to a site with high affinity (Ksub(D) = 10.5 nM) in a saturable manner (Bsub(max) = 15.4 pmol/g wet weight in the cerebral cortex). The number of binding sites in the various regions of the brain parallels the capacity of the 5-HT reuptake mechanism. Drugs that inhibit the reuptake of 5-HT are also potent inhibitors of the 3 H-norzimeldine binding, as are the tricyclic antidepressants, which are non-specific inhibitors of the noradrenaline and the 5-HT reuptake. Lesioning experiments using DSP4 (a NA neurotoxin) and p-chloroamphetamine (a 5-HT neurotoxin) suggest that the binding site is located on the presynaptic 5-HT nerve terminal, although a small component of the binding may be to noradrenergic uptake sites as well.(author)

Fabrication and characterization of inverted organic solar cells using shuttle cock-type metal phthalocyanine and PCBM:P3HT

Energy Technology Data Exchange (ETDEWEB)

Suzuki, Atsushi, E-mail: suzuki@mat.usp.ac.jp; Furukawa, Ryo, E-mail: suzuki@mat.usp.ac.jp; Akiyama, Tsuyoshi, E-mail: suzuki@mat.usp.ac.jp; Oku, Takeo, E-mail: suzuki@mat.usp.ac.jp [Department of Materials Science, The University of Shiga Prefecture 2500 Hassaka, Hikone, Shiga 522-8533 (Japan)

2015-02-27

Inverted organic solar cells using shuttle cock-type phthalocyanine, semiconducting polymer and fullerenes were fabricated and characterized. Photovoltaic and optical properties of the solar cells with inverted structures were investigated by optical absorption, current density-voltage characteristics. The photovoltaic properties of the tandem organic solar cell using titanyl phthalocyanine, vanadyl phthalocyanine, poly(3-hexylthiophene) (P3HT) and [6, 6]-phenyl C{sub 61}-butyric acid methyl ester (PCBM) were improved. Effect of annealing and solvent treatment on surface morphologies of the active layer was investigated. The photovoltaic mechanisms, energy levels and band gap of active layers were discussed for improvement of the photovoltaic performance.

Fabrication and characterization of inverted organic solar cells using shuttle cock-type metal phthalocyanine and PCBM:P3HT

International Nuclear Information System (INIS)

Suzuki, Atsushi; Furukawa, Ryo; Akiyama, Tsuyoshi; Oku, Takeo

2015-01-01

Inverted organic solar cells using shuttle cock-type phthalocyanine, semiconducting polymer and fullerenes were fabricated and characterized. Photovoltaic and optical properties of the solar cells with inverted structures were investigated by optical absorption, current density-voltage characteristics. The photovoltaic properties of the tandem organic solar cell using titanyl phthalocyanine, vanadyl phthalocyanine, poly(3-hexylthiophene) (P3HT) and [6, 6]-phenyl C 61 -butyric acid methyl ester (PCBM) were improved. Effect of annealing and solvent treatment on surface morphologies of the active layer was investigated. The photovoltaic mechanisms, energy levels and band gap of active layers were discussed for improvement of the photovoltaic performance

Human arm stiffness and equilibrium-point trajectory during multi-joint movement.

Science.gov (United States)

Gomi, H; Kawato, M

1997-03-01

By using a newly designed high-performance manipulandum and a new estimation algorithm, we measured human multi-joint arm stiffness parameters during multi-joint point-to-point movements on a horizontal plane. This manipulandum allows us to apply a sufficient perturbation to subject's arm within a brief period during movement. Arm stiffness parameters were reliably estimated using a new algorithm, in which all unknown structural parameters could be estimated independent of arm posture (i.e., constant values under any arm posture). Arm stiffness during transverse movement was considerably greater than that during corresponding posture, but not during a longitudinal movement. Although the ratios of elbow, shoulder, and double-joint stiffness were varied in time, the orientation of stiffness ellipses during the movement did not change much. Equilibrium-point trajectories that were predicted from measured stiffness parameters and actual trajectories were slightly sinusoidally curved in Cartesian space and their velocity profiles were quite different from the velocity profiles of actual hand trajectories. This result contradicts the hypothesis that the brain does not take the dynamics into account in movement control depending on the neuromuscular servo mechanism; rather, it implies that the brain needs to acquire some internal models of controlled objects.

Flail arm-like syndrome associated with HIV-1 infection

Directory of Open Access Journals (Sweden)

Nalini A

2009-01-01

Full Text Available During the last 20 years at least 23 cases of motor neuron disease have been reported in HIV-1 seropositive patients. In this report we describe the clinical picture of a young man with HIV-1 clade C infection and flail arm-like syndrome, who we were able to follow-up for a long period. We investigated and prospectively monitored a 34-year-old man with features of flail arm syndrome, who developed the weakness and wasting 1 year after being diagnosed with HIV-1 infection after a routine blood test. He presented in 2003 with progressive, symmetrical wasting and weakness of the proximal muscles of the upper limb of 2 years′ duration. He had severe wasting and weakness of the shoulder and arm muscles. There were no pyramidal signs. He has been on HAART for the last 4 years and the weakness or wasting has not worsened. At the last follow-up in July 2007, the patient had the same neurological deficit and no other symptoms or signs of HIV-1 infection. MRI of the spinal cord in 2007 showed characteristic T2 hyperintense signals in the central part of the spinal cord, corresponding to the central gray matter. Thus, our patient had HIV-1 clade C infection associated with a ′flail arm-like syndrome.′ The causal relationship between HIV-1 infection and amyotrophic lateral sclerosis (ALS-like syndrome is still uncertain. The syndrome usually manifests as a lower motor neuron syndrome, as was seen in our young patient. It is known that treatment with antiretroviral therapy (ART stabilizes/improves the condition. In our patient the weakness and atrophy remained stable over a period of 3.5 years after commencing HAART regimen.

Functional expression of 5-HT{sub 2A} receptor in osteoblastic MC3T3-E1 cells

Energy Technology Data Exchange (ETDEWEB)

Hirai, Takao; Kaneshige, Kota; Kurosaki, Teruko [Department of Molecular Pharmacology, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, 1 Gakuen-cho, Fukuyama, Hiroshima 729-0292 (Japan); Nishio, Hiroaki, E-mail: nishio@fupharm.fukuyama-u.ac.jp [Department of Molecular Pharmacology, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, 1 Gakuen-cho, Fukuyama, Hiroshima 729-0292 (Japan)

2010-05-28

In the previous study, we reported the gene expression for proteins related to the function of 5-hydroxytryptamine (5-HT, serotonin) and elucidated the expression patterns of 5-HT{sub 2} receptor subtypes in mouse osteoblasts. In the present study, we evaluated the possible involvement of 5-HT receptor subtypes and its inactivation system in MC3T3-E1 cells, an osteoblast cell line. DOI, a 5-HT{sub 2A} and 5-HT{sub 2C} receptor selective agonist, as well as 5-HT concentration-dependently increased proliferative activities of MC3T3-E1 cells in their premature period. This effect of 5-HT on cell proliferation were inhibited by ketanserin, a 5-HT{sub 2A} receptor specific antagonist. Moreover, both DOI-induced cell proliferation and phosphorylation of ERK1 and 2 proteins were inhibited by PD98059 and U0126, selective inhibitors of MEK in a concentration-dependent manner. Furthermore, treatment with fluoxetine, a 5-HT specific re-uptake inhibitor which inactivate the function of extracellular 5-HT, significantly increased the proliferative activities of MC3T3-E1 cells in a concentration-dependent manner. Our data indicate that 5-HT fill the role for proliferation of osteoblast cells in their premature period. Notably, 5-HT{sub 2A} receptor may be functionally expressed to regulate mechanisms underlying osteoblast cell proliferation, at least in part, through activation of ERK/MAPK pathways in MC3T3-E1 cells.

Hallucinogenic 5-HT2AR agonists LSD and DOI enhance dopamine D2R protomer recognition and signaling of D2-5-HT2A heteroreceptor complexes.

Science.gov (United States)

Borroto-Escuela, Dasiel O; Romero-Fernandez, Wilber; Narvaez, Manuel; Oflijan, Julia; Agnati, Luigi F; Fuxe, Kjell

2014-01-03

Dopamine D2LR-serotonin 5-HT2AR heteromers were demonstrated in HEK293 cells after cotransfection of the two receptors and shown to have bidirectional receptor-receptor interactions. In the current study the existence of D2L-5-HT2A heteroreceptor complexes was demonstrated also in discrete regions of the ventral and dorsal striatum with in situ proximity ligation assays (PLA). The hallucinogenic 5-HT2AR agonists LSD and DOI but not the standard 5-HT2AR agonist TCB2 and 5-HT significantly increased the density of D2like antagonist (3)H-raclopride binding sites and significantly reduced the pKiH values of the high affinity D2R agonist binding sites in (3)H-raclopride/DA competition experiments. Similar results were obtained in HEK293 cells and in ventral striatum. The effects of the hallucinogenic 5-HT2AR agonists on D2R density and affinity were blocked by the 5-HT2A antagonist ketanserin. In a forskolin-induced CRE-luciferase reporter gene assay using cotransfected but not D2R singly transfected HEK293 cells DOI and LSD but not TCB2 significantly enhanced the D2LR agonist quinpirole induced inhibition of CRE-luciferase activity. Haloperidol blocked the effects of both quinpirole alone and the enhancing actions of DOI and LSD while ketanserin only blocked the enhancing actions of DOI and LSD. The mechanism for the allosteric enhancement of the D2R protomer recognition and signalling observed is likely mediated by a biased agonist action of the hallucinogenic 5-HT2AR agonists at the orthosteric site of the 5-HT2AR protomer. This mechanism may contribute to the psychotic actions of LSD and DOI and the D2-5-HT2A heteroreceptor complex may thus be a target for the psychotic actions of hallunicogenic 5-HT2A agonists. Copyright © 2013 Elsevier Inc. All rights reserved.

The Role of 5-HT3 Receptors in Signaling from Taste Buds to Nerves.

Science.gov (United States)

Larson, Eric D; Vandenbeuch, Aurelie; Voigt, Anja; Meyerhof, Wolfgang; Kinnamon, Sue C; Finger, Thomas E

2015-12-02

Activation of taste buds triggers the release of several neurotransmitters, including ATP and serotonin (5-hydroxytryptamine; 5-HT). Type III taste cells release 5-HT directly in response to acidic (sour) stimuli and indirectly in response to bitter and sweet tasting stimuli. Although ATP is necessary for activation of nerve fibers for all taste stimuli, the role of 5-HT is unclear. We investigated whether gustatory afferents express functional 5-HT3 receptors and, if so, whether these receptors play a role in transmission of taste information from taste buds to nerves. In mice expressing GFP under the control of the 5-HT(3A) promoter, a subset of cells in the geniculate ganglion and nerve fibers in taste buds are GFP-positive. RT-PCR and in situ hybridization confirmed the presence of 5-HT(3A) mRNA in the geniculate ganglion. Functional studies show that only those geniculate ganglion cells expressing 5-HT3A-driven GFP respond to 10 μM 5-HT and this response is blocked by 1 μM ondansetron, a 5-HT3 antagonist, and mimicked by application of 10 μM m-chlorophenylbiguanide, a 5-HT3 agonist. Pharmacological blockade of 5-HT3 receptors in vivo or genetic deletion of the 5-HT3 receptors reduces taste nerve responses to acids and other taste stimuli compared with controls, but only when urethane was used as the anesthetic. We find that anesthetic levels of pentobarbital reduce taste nerve responses apparently by blocking the 5-HT3 receptors. Our results suggest that 5-HT released from type III cells activates gustatory nerve fibers via 5-HT3 receptors, accounting for a significant proportion of the neural taste response. Copyright © 2015 the authors 0270-6474/15/3515984-12$15.00/0.

Neuropeptide AF induces anxiety-like and antidepressant-like behavior in mice.

Science.gov (United States)

Palotai, Miklós; Telegdy, Gyula; Tanaka, Masaru; Bagosi, Zsolt; Jászberényi, Miklós

2014-11-01

Little is known about the action of neuropeptide AF (NPAF) on anxiety and depression. Only our previous study provides evidence that NPAF induces anxiety-like behavior in rats. Therefore, the aim of the present study was to investigate the action of NPAF on depression-like behavior and the underlying neurotransmissions in mice. In order to determine whether there are species differences between rats and mice, we have investigated the action of NPAF on anxiety-like behavior in mice as well. A modified forced swimming test (mFST) and an elevated plus maze test (EPMT) were used to investigate the depression and anxiety-related behaviors, respectively. Mice were treated with NPAF 30min prior to the tests. In the mFST, the animals were pretreated with a non-selective muscarinic acetylcholine receptor antagonist, atropine, a non-selective 5-HT2 serotonergic receptor antagonist, cyproheptadine, a mixed 5-HT1/5-HT2 serotonergic receptor antagonist, methysergide, a D2/D3/D4 dopamine receptor antagonist, haloperidol, a α1/α2β-adrenergic receptor antagonist, prazosin or a non-selective β-adrenergic receptor antagonist, propranolol 30min before the NPAF administration. In the mFST, NPAF decreased the immobility time and increased the climbing and swimming times. This action was reversed completely by methysergide and partially by atropine, whereas cyproheptadine, haloperidol, prazosin and propranolol were ineffective. In the EPMT, NPAF decreased the time spent in the arms (open/open+closed). Our results demonstrate that NPAF induces anti-depressant-like behavior in mice, which is mediated, at least in part, through 5HT2-serotonergic and muscarinic cholinergic neurotransmissions. In addition, the NPAF-induced anxiety is species-independent, since it develops also in mice. Copyright © 2014 Elsevier B.V. All rights reserved.

PEDOT: PSS: rGO nanocomposite as a hole transport layer (HTLs) for P3HT:PCBM based organic solar cells

Science.gov (United States)

Tiwari, D. C.; Dwivedi, Shailendra Kumar; Dipak, Pukhrambam; Chandel, Tarun

2018-05-01

This paper reports the fabrication process of organic solar cell (OSCs) having structure ITO/PEDOT:PSS:rGO/P3HT:PCBM/Al. In this cell, poly (3, 4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS) is ultrasonically mixed with thermally reduced graphene oxide (rGO), which was used as a hole transport layer (HTLs). In order to investigate structural, morphological and optical properties of nanocomposite, XRD, FE-SEM and UV-vis spectroscopy were carried out. We have observed, Jsc = 6.5mA/cm2, Voc = 212 mV, FF=0.31 and PCE of 0.43% from fabricated organic solar cell.

Effects of constant voltage and constant current stress in PCBM:P3HT solar cells

DEFF Research Database (Denmark)

Cester, Andrea; Rizzo, Aldo; Bazzega, A.

2015-01-01

The aimof this work is the investigation of forward and reverse bias stress effects, cell self-heating and annealing in roll coated organic solar cells with PCBM:P3HT active layer. In reverse bias stress cells show a constant degradation over time. In forward current stress cells alternate...... mechanisms: the decrease of the net generation rate (due to formation of exciton quenching centres or the reduction of exciton separation rate); the formation of small leaky paths between anode and cathode, which reduces the total current extracted from the cell. The stress-induced damage can be recovered...... degradation and annealing phases, which are explained through the high power dissipation during the current stress, and the consequent self-heating. The high temperature is able to recover the cell performances at least until a critical temperature is reached. The degradation can be explained by the following...

Is life most likely around Sun-like stars?

Science.gov (United States)

Lingam, Manasvi; Loeb, Abraham

2018-05-01

We consider the habitability of Earth-analogs around stars of different masses, which is regulated by the stellar lifetime, stellar wind-induced atmospheric erosion, and biologically active ultraviolet (UV) irradiance. By estimating the timescales associated with each of these processes, we show that they collectively impose limits on the habitability of Earth-analogs. We conclude that planets orbiting most M-dwarfs are not likely to host life, and that the highest probability of complex biospheres is for planets around K- and G-type stars. Our analysis suggests that the current existence of life near the Sun is slightly unusual, but not significantly anomalous.

Optimum Design of Multi-Function Robot Arm Gripper for Varying Shape Green Product

Directory of Open Access Journals (Sweden)

Razali Zol Bahri

2016-01-01

Full Text Available The project focuses on thorough experimentally studies of the optimum design of Multi-function Robot Arm Gripper for varying shape green product. The purpose of this project is to design a few of robot arm gripper for multi-functionally grip a green product with varying shape. The main character of the gripper is that it can automated adjust its finger to suit with the shape of the product. An optimum design of multi-function robot arm gripper is verified through experimental study. The expected result is a series of analytical results on the proposal of gripper design and material that will be selected for the gripper. The analysis of the gripper design proposal by using ANSYS and CATIA software is described in detail in this paper.

The NuSTAR Hard X-Ray Survey of the Norma Arm Region

DEFF Research Database (Denmark)

Fornasini, Francesca M.; Tomsick, John A.; Hong, JaeSub

2017-01-01

We present a catalog of hard X-ray sources in a square-degree region surveyed by the Nuclear Spectroscopic Telescope Array (NuSTAR) in the direction of the Norma spiral arm. This survey has a total exposure time of 1.7 Ms, and the typical and maximum exposure depths are 50 ks and 1 Ms, respectively...... model with kT ≈ 15 keV, as observed for the CV candidates....

Functional antagonistic properties of clozapine at the 5-HT3 receptor.

Science.gov (United States)

Hermann, B; Wetzel, C H; Pestel, E; Zieglgänsberger, W; Holsboer, F; Rupprecht, R

1996-08-23

The atypical neuroleptic clozapine is thought to exert its psychopharmacological actions through a variety of neurotransmitter receptors. It binds preferentially to D4 and 5-HT2 receptors; however, little is known on it's interaction with the 5-HT3 receptor. Using a cell line stably expressing the 5-HT3 receptor, whole-cell voltage-clamp analysis revealed functional antagonistic properties of clozapine at low nanomolar concentrations in view of a binding affinity in the upper nanomolar range. Because the concentration of clozapine required for an interaction with the 5-HT3 receptor can be achieved with therapeutical doses, functional antagonistic properties at this ligand-gated ion channel may contribute to its unique psychopharmacological profile.

Postnatal development of progeny after 5-HT and/or 32P treatment of mice on the first day of gestation

International Nuclear Information System (INIS)

Manowska, Jadwiga; Mazur, Lidia

1986-01-01

C57B mice were injected intraperitoneally with 5-HT (serotonin-creatinine sulphate) in a dose of 40 mg/kg body weight and/or radioactive P in the form of Na 2 H 32 PO 4 in a dose of 1 μCi/g body weight, on the first day of gestation. Litter size of newborns, and growth and mortality of progeny during the postnatal thirty days were determined. As compared with controls, the litter size of newborns was smaller in mice treated with 32 P or 5-HT; the smallest one was found among those injected with 5-HT and 32 P. The sex ratio of newborns was disturbed only in animals treated with 5-HT. The mortality of progeny occurred only in mice treated with 32 P. Body weight in relation to controls was lower in mice injected with both 5-HT and 32 P, and also in those receiving 32 P only but it was greater during lactation in those treated with 5-HT. Under these experimental conditions, 5-HT did not show a radioprotective role. (author)

Synthesis of Well-Defined Three-Arm Star-Branched Polystyrene through Arm-First Coupling Approach by Atom Transfer Radical Polymerization

OpenAIRE

Shahabuddin, Syed; Hamime Ismail, Fatem; Mohamad, Sharifah; Muhamad Sarih, Norazilawati

2015-01-01

Here we describe a simple route to synthesize three-arm star-branched polystyrene. Atom transfer radical polymerization technique has been utilized to yield branched polystyrene involving Williamson coupling strategy. Initially a linear polymeric chain of predetermined molecular weight has been synthesized which is further end-functionalized into a primary alkyl bromide moiety, a prime requisition for Williamson reaction. The end-functionalized polymer is then coupled using 1,1,1-tris(4-hydro...

Smooth-arm spiral galaxies: their properties and significance to cluster-galaxy evolution

International Nuclear Information System (INIS)

Wilkerson, M.S.

1979-01-01

In this dissertation a number of galaxies with optical appearances between those of normal, actively-star-forming spirals and SO galaxies have been examined. These so-called smooth-arm spiral galaxies exhibit spiral arms without any of the spiral tracers - H II regions, O-B star associations, dust - indicative of current star formation. Tests were made to find if, perhaps, these smooth-arm spirals could have, at one time, been normal, actively-star-forming spirals whose gas had been somehow removed; and that are currently transforming into SO galaxies. This scenario proceeds as (1) removal of gas, (2) gradual dying of disk density wave, (3) emergence of SO galaxy. If the dominant method of gas removal is ram-pressure stripping by a hot, intracluster medium, then smooth-arm spirals should occur primarily in x-ray clusters. Some major findings of this dissertation are as follows: (1) Smooth-arm spirals are redder than normal spirals of the same morphological type. Most smooth-arm spirals cannot be distinguished by color from SO galaxies. (2) A weak trend exists for smooth-arm spirals with stronger arms to be bluer than those with weaker arms; thus implying that the interval since gas removal has been shorter for the galaxies with stronger arms. (3) Smooth-arm spirals are deficient in neutral hydrogen - sometimes by an order of magnitude or, possibly, more

Anxiolytic-like effects of alverine citrate in experimental mouse models of anxiety.

Science.gov (United States)

Gupta, Deepali; Radhakrishnan, Mahesh; Kurhe, Yeshwant

2014-11-05

Anxiety disorders are widely spread psychiatric illnesses that are a cause of major concern. Despite a consistent increase in anxiolytics, the prevalence of anxiety is static; this necessitates the development of new compounds with potential activity and minimum unwanted effects. A serotonergic (5HT) system plays an important role in pathogenesis of anxiety and predominantly involves 5HT1A receptor action in mediating anxiety-like behavior; the antagonism of 5HT1A receptor has demonstrated to produce anxiolytic-like effects. Alverine citrate (AVC) is reported as a 5HT1A antagonist; however, its effects on anxiety-like behavior are not investigated. Thus, the present study, by utilizing a neurobehavioral approach, examined the anxiolytic-like effects of AVC in experimental mouse models of anxiety. Mice were acutely treated with AVC (5-20mg/kg, i.p.)/diazepam (DIA, 2mg/kg, i.p.) and subjected to four validated anxiety models viz. elevated plus-maze (EPM), light/dark (L/D), hole-board (HB) and marble burying (MB) tests. AVC (15-20mg/kg) and DIA significantly increased open arm activity in EPM, exploration in light chamber in L/D test, exploratory behavior in HB and reduced MB behavior in marble burying test. AVC (5mg/kg) had no effect on all behavioral tests, while AVC (10mg/kg) produced partial effects. It revealed anxiolytic-like effects of AVC. Furthermore, anxiolytic-like effects of AVC at higher doses (15-20mg/kg) were more pronounced than lower doses (10mg/kg) and were quite similar to the standard drug DIA. The present finding demonstrates, for the first time, the anxiolytic-like effects of AVC, which may be an alternative approach for management of anxiety-related disorders. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of the binding of /sup 3/H-norzimeldine, a 5-HT uptake inhibitor, to rat brain homogenates

Energy Technology Data Exchange (ETDEWEB)

Hall, H. (Department of Biochemical Neuropharmacology, Research and Development Laboratories, Astra Laekemedel, Soedertaelje, Sweden)

1984-01-01

The binding of radiolabelled norzimeldine, a potent selective 5-HT reuptake inhibitor, to rat brain homogenates is described. /sup 3/H-Norzimeldine binds to a site with high affinity (Ksub(D) = 10.5 nM) in a saturable manner (Bsub(max) = 15.4 pmol/g wet weight in the cerebral cortex). The number of binding sites in the various regions of the brain parallels the capacity of the 5-HT reuptake mechanism. Drugs that inhibit the reuptake of 5-HT are also potent inhibitors of the /sup 3/H-norzimeldine binding, as are the tricyclic antidepressants, which are non-specific inhibitors of the noradrenaline and the 5-HT reuptake. Lesioning experiments using DSP4 (a NA neurotoxin) and p-chloroamphetamine (a 5-HT neurotoxin) suggest that the binding site is located on the presynaptic 5-HT nerve terminal, although a small component of the binding may be to noradrenergic uptake sites as well.

Annealed star-branched polyelectrolytes in solution

NARCIS (Netherlands)

Klein Wolterink, J.; Male, van J.; Cohen Stuart, M.A.; Koopal, L.K.; Zhulina, E.B.; Borisov, O.V.

2002-01-01

Equilibrium conformations of annealed star-branched polyelectrolytes (polyacids) are calculated with a numerical self-consistent-field (SCF) model. From the calculations we obtain also the size and charge of annealed polyelectrolyte stars as a function of the number of arms, pH, and the ionic

Analysis of the Herschel DEBRIS Sun-like star sample

Science.gov (United States)

Sibthorpe, B.; Kennedy, G. M.; Wyatt, M. C.; Lestrade, J.-F.; Greaves, J. S.; Matthews, B. C.; Duchêne, G.

2018-04-01

This paper presents a study of circumstellar debris around Sun-like stars using data from the Herschel DEBRIS Key Programme. DEBRIS is an unbiased survey comprising the nearest ˜90 stars of each spectral type A-M. Analysis of the 275 F-K stars shows that excess emission from a debris disc was detected around 47 stars, giving a detection rate of 17.1^{+2.6}_{-2.3} per cent, with lower rates for later spectral types. For each target a blackbody spectrum was fitted to the dust emission to determine its fractional luminosity and temperature. The derived underlying distribution of fractional luminosity versus blackbody radius in the population showed that most detected discs are concentrated at f ˜ 10-5 and at temperatures corresponding to blackbody radii 7-40 au, which scales to ˜40 au for realistic dust properties (similar to the current Kuiper belt). Two outlying populations are also evident; five stars have exceptionally bright emission ( f > 5 × 10-5), and one has unusually hot dust <4 au. The excess emission distributions at all wavelengths were fitted with a steady-state evolution model, showing that these are compatible with all stars being born with a narrow belt that then undergoes collisional grinding. However, the model cannot explain the hot dust systems - likely originating in transient events - and bright emission systems - arising potentially from atypically massive discs or recent stirring. The emission from the present-day Kuiper belt is predicted to be close to the median of the population, suggesting that half of stars have either depleted their Kuiper belts (similar to the Solar system) or had a lower planetesimal formation efficiency.

Consequences of Anode Interfacial Layer Deletion. HCl-Treated ITO in P3HT:PCBM-Based Bulk-Heterojunction Organic Photovoltaic Devices

Science.gov (United States)

2010-01-01

followed by centrifugation. P3HT53was purchased from RiekeMetals, Inc., andwas further purified by sequential Soxhlet extractions with methanol and...19.8 nA (σ=31.1 nA, Figure 2c), and scanning under the same conditions on HCl-treated ITO yields Imean=9.11 nA (σ=12.5 nA, Figure 2d). As seen...0.01:1.0, and the respective combination ofHCl treatment and 10minUVOalso yields 0.23( 0.01:1.0, remarkably similar to an ITO surface treated with RIE

Determination of the interaction parameter and topological scaling features of symmetric star polymers in dilute solution

KAUST Repository

Rai, Durgesh K.; Beaucage, Gregory; Ratkanthwar, Kedar; Beaucage, Peter; Ramachandran, Ramnath; Hadjichristidis, Nikolaos

2015-01-01

Star polymers provide model architectures to understand the dynamic and rheological effects of chain confinement for a range of complex topological structures like branched polymers, colloids, and micelles. It is important to describe the structure of such macromolecular topologies using small-angle neutron and x-ray scattering to facilitate understanding of their structure-property relationships. Modeling of scattering from linear, Gaussian polymers, such as in the melt, has applied the random phase approximation using the Debye polymer scattering function. The Flory-Huggins interaction parameter can be obtained using neutron scattering by this method. Gaussian scaling no longer applies for more complicated chain topologies or when chains are in good solvents. For symmetric star polymers, chain scaling can differ from ν=0.5(df=2) due to excluded volume, steric interaction between arms, and enhanced density due to branching. Further, correlation between arms in a symmetric star leads to an interference term in the scattering function first described by Benoit for Gaussian chains. In this work, a scattering function is derived which accounts for interarm correlations in symmetric star polymers as well as the polymer-solvent interaction parameter for chains of arbitrary scaling dimension using a hybrid Unified scattering function. The approach is demonstrated for linear, four-arm and eight-arm polyisoprene stars in deuterated p-xylene.

Determination of the interaction parameter and topological scaling features of symmetric star polymers in dilute solution

KAUST Repository

Rai, Durgesh K.

2015-07-15

Star polymers provide model architectures to understand the dynamic and rheological effects of chain confinement for a range of complex topological structures like branched polymers, colloids, and micelles. It is important to describe the structure of such macromolecular topologies using small-angle neutron and x-ray scattering to facilitate understanding of their structure-property relationships. Modeling of scattering from linear, Gaussian polymers, such as in the melt, has applied the random phase approximation using the Debye polymer scattering function. The Flory-Huggins interaction parameter can be obtained using neutron scattering by this method. Gaussian scaling no longer applies for more complicated chain topologies or when chains are in good solvents. For symmetric star polymers, chain scaling can differ from ν=0.5(df=2) due to excluded volume, steric interaction between arms, and enhanced density due to branching. Further, correlation between arms in a symmetric star leads to an interference term in the scattering function first described by Benoit for Gaussian chains. In this work, a scattering function is derived which accounts for interarm correlations in symmetric star polymers as well as the polymer-solvent interaction parameter for chains of arbitrary scaling dimension using a hybrid Unified scattering function. The approach is demonstrated for linear, four-arm and eight-arm polyisoprene stars in deuterated p-xylene.

Selective labelling of 5-HT7 receptor recognition sites in rat brain using [3H]5-carboxamidotryptamine

International Nuclear Information System (INIS)

Stowe, R.L.; Barnes, N.M.

1998-01-01

The aim of the present study was to establish a radioligand binding assay to selectively label the native 5-HT 7 receptor expressed in rat brain. In rat whole brain (minus cerebellum and striatum) homogenate, (±)-pindolol (10 μM)-insensitive [ 3 H]5-CT ([ 3 H]5-carboxamidotryptamine; 0.5 nM) specific binding (defined by 5-HT, 10 μM) displayed a pharmacological profile similar to the recombinant 5-HT 7 receptor, although the Hill coefficients for competition curves generated by methiothepin, ritanserin, sumatriptan, clozapine and pimozide were significantly less than unity. In homogenates of rat hypothalamus, (±)-pindolol (10 μM)-insensitive [ 3 H]5-CT recognition sites also resembled, pharmacologically, the 5-HT 7 receptor, although pimozide still generated Hill coefficients significantly less than unity. Subsequent studies were performed in the additional presence of WAY100635 (100 nM) to prevent [ 3 H]5-CT binding to residual, possibly, 5-HT 1A sites. Competition for this [ 3 H]5-CT binding indicated the labelling in whole rat brain homogenate of a homogenous population of sites with the pharmacological profile of the 5-HT 7 receptor. Saturation studies also indicated that (±)-pindolol (10 μM)/WAY 100635 (100 nM)-insensitive [ 3 H]5-CT binding to homogenates of whole rat brain was saturable and to an apparently homogenous population of sites which were labelled with nanomolar affinity (B max =33.2±0.7 fmol mg -1 protein, pK d =8.78±0.05, mean±S.E.M., n=3). The development of this 5-HT 7 receptor binding assay will aid investigation of the rat native 5-HT 7 receptor. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

Closed-Loop Neuroprosthesis for Reach-to-Grasp Assistance: Combining Adaptive Multi-channel Neuromuscular Stimulation with a Multi-joint Arm Exoskeleton.

Science.gov (United States)

Grimm, Florian; Gharabaghi, Alireza

2016-01-01

Stroke patients with severe motor deficits cannot execute task-oriented rehabilitation exercises with their affected upper extremity. Advanced rehabilitation technology may support them in performing such reach-to-grasp movements. The challenge is, however, to provide assistance as needed, while maintaining the participants' commitment during the exercises. In this feasibility study, we introduced a closed-loop neuroprosthesis for reach-to-grasp assistance which combines adaptive multi-channel neuromuscular stimulation with a multi-joint arm exoskeleton. Eighteen severely affected chronic stroke patients were assisted by a gravity-compensating, seven-degree-of-freedom exoskeleton which was attached to the paretic arm for performing reach-to-grasp exercises resembling activities of daily living in a virtual environment. During the exercises, adaptive electrical stimulation was applied to seven different muscles of the upper extremity in a performance-dependent way to enhance the task-oriented movement trajectory. The stimulation intensity was individualized for each targeted muscle and remained subthreshold, i.e., induced no overt support. Closed-loop neuromuscular stimulation could be well integrated into the exoskeleton-based training, and increased the task-related range of motion (p = 0.0004) and movement velocity (p = 0.015), while preserving accuracy. The highest relative stimulation intensity was required to facilitate the grasping function. The facilitated range of motion correlated with the upper extremity Fugl-Meyer Assessment score of the patients (p = 0.028). Combining adaptive multi-channel neuromuscular stimulation with antigravity assistance amplifies the residual motor capabilities of severely affected stroke patients during rehabilitation exercises and may thus provide a customized training environment for patient-tailored support while preserving the participants' engagement.

Closed-Loop Neuroprosthesis for Reach-to-Grasp Assistance: Combining Adaptive Multi-channel Neuromuscular Stimulation with a Multi-joint Arm Exoskeleton

Science.gov (United States)

Grimm, Florian; Gharabaghi, Alireza

2016-01-01

Stroke patients with severe motor deficits cannot execute task-oriented rehabilitation exercises with their affected upper extremity. Advanced rehabilitation technology may support them in performing such reach-to-grasp movements. The challenge is, however, to provide assistance as needed, while maintaining the participants' commitment during the exercises. In this feasibility study, we introduced a closed-loop neuroprosthesis for reach-to-grasp assistance which combines adaptive multi-channel neuromuscular stimulation with a multi-joint arm exoskeleton. Eighteen severely affected chronic stroke patients were assisted by a gravity-compensating, seven-degree-of-freedom exoskeleton which was attached to the paretic arm for performing reach-to-grasp exercises resembling activities of daily living in a virtual environment. During the exercises, adaptive electrical stimulation was applied to seven different muscles of the upper extremity in a performance-dependent way to enhance the task-oriented movement trajectory. The stimulation intensity was individualized for each targeted muscle and remained subthreshold, i.e., induced no overt support. Closed-loop neuromuscular stimulation could be well integrated into the exoskeleton-based training, and increased the task-related range of motion (p = 0.0004) and movement velocity (p = 0.015), while preserving accuracy. The highest relative stimulation intensity was required to facilitate the grasping function. The facilitated range of motion correlated with the upper extremity Fugl-Meyer Assessment score of the patients (p = 0.028). Combining adaptive multi-channel neuromuscular stimulation with antigravity assistance amplifies the residual motor capabilities of severely affected stroke patients during rehabilitation exercises and may thus provide a customized training environment for patient-tailored support while preserving the participants' engagement. PMID:27445658

RECENT STAR FORMATION IN THE LEADING ARM OF THE MAGELLANIC STREAM

Energy Technology Data Exchange (ETDEWEB)

Casetti-Dinescu, Dana I. [Department of Physics, Southern Connecticut State University, 501 Crescent Street, New Haven, CT 06515 (United States); Bidin, Christian Moni [Instituto de Astronomía, Universidad Católica del Norte, Avenue Angamos 0610, Antofagasta (Chile); Girard, Terrence M.; Van Altena, William F. [Astronomy Department, Yale University, 260 Whitney Avenue, New Haven, CT 06511 (United States); Méndez, Réne A. [Departmento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile); Vieira, Katherine [Centro de Investigaciones de Astronomía, Apartado Postal 264, Mérida 5101-A (Venezuela, Bolivarian Republic of); Korchagin, Vladimir I., E-mail: casettid1@southernct.edu, E-mail: dana.casetti@yale.edu, E-mail: terry.girard@yale.edu, E-mail: william.vanaltena@yale.edu, E-mail: chr.moni.bidin@gmail.com, E-mail: ramendez.uchile@gmail.com, E-mail: kvieira@cida.ve, E-mail: vkorchagin@sfedu.ru [Institute of Physics, Southern Federal University, Stachki Street 124, 344090, Rostov-on-Don (Russian Federation)

2014-04-01

Strongly interacting galaxies undergo a short-lived but dramatic phase of evolution characterized by enhanced star formation, tidal tails, bridges, and other morphological peculiarities. The nearest example of a pair of interacting galaxies is the Magellanic Clouds, whose dynamical interaction produced the gaseous features known as the Magellanic Stream trailing the pair's orbit about the Galaxy, the bridge between the Clouds, and the leading arm (LA), a wide and irregular feature leading the orbit. Young, newly formed stars in the bridge are known to exist, giving witness to the recent interaction between the Clouds. However, the interaction of the Clouds with the Milky Way (MW) is less well understood. In particular, the LA must have a tidal origin; however, no purely gravitational model is able to reproduce its morphology and kinematics. A hydrodynamical interaction with the gaseous hot halo and disk of the Galaxy is plausible as suggested by some models and supporting neutral hydrogen (H I) observations. Here we show for the first time that young, recently formed stars exist in the LA, indicating that the interaction between the Clouds and our Galaxy is strong enough to trigger star formation in certain regions of the LA—regions in the outskirts of the MW disk (R ∼ 18 kpc), far away from the Clouds and the bridge.

RECENT STAR FORMATION IN THE LEADING ARM OF THE MAGELLANIC STREAM

International Nuclear Information System (INIS)

Casetti-Dinescu, Dana I.; Bidin, Christian Moni; Girard, Terrence M.; Van Altena, William F.; Méndez, Réne A.; Vieira, Katherine; Korchagin, Vladimir I.

2014-01-01

Strongly interacting galaxies undergo a short-lived but dramatic phase of evolution characterized by enhanced star formation, tidal tails, bridges, and other morphological peculiarities. The nearest example of a pair of interacting galaxies is the Magellanic Clouds, whose dynamical interaction produced the gaseous features known as the Magellanic Stream trailing the pair's orbit about the Galaxy, the bridge between the Clouds, and the leading arm (LA), a wide and irregular feature leading the orbit. Young, newly formed stars in the bridge are known to exist, giving witness to the recent interaction between the Clouds. However, the interaction of the Clouds with the Milky Way (MW) is less well understood. In particular, the LA must have a tidal origin; however, no purely gravitational model is able to reproduce its morphology and kinematics. A hydrodynamical interaction with the gaseous hot halo and disk of the Galaxy is plausible as suggested by some models and supporting neutral hydrogen (H I) observations. Here we show for the first time that young, recently formed stars exist in the LA, indicating that the interaction between the Clouds and our Galaxy is strong enough to trigger star formation in certain regions of the LA—regions in the outskirts of the MW disk (R ∼ 18 kpc), far away from the Clouds and the bridge

ARM Airborne Carbon Measurements (ARM-ACME) and ARM-ACME 2.5 Final Campaign Reports

Energy Technology Data Exchange (ETDEWEB)

Biraud, S. C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Tom, M. S. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sweeney, C. [NOAA Earth Systems Research Lab., Boulder, CO (United States)

2016-01-01

We report on a 5-year multi-institution and multi-agency airborne study of atmospheric composition and carbon cycling at the Atmospheric Radiation Measurement (ARM) Climate Research Facility’s Southern Great Plains (SGP) site, with scientific objectives that are central to the carbon-cycle and radiative-forcing goals of the U.S. Global Change Research Program and the North American Carbon Program (NACP). The goal of these measurements is to improve understanding of 1) the carbon exchange of the Atmospheric Radiation Measurement (ARM) SGP region; 2) how CO₂ and associated water and energy fluxes influence radiative-forcing, convective processes, and CO₂ concentrations over the ARM SGP region, and 3) how greenhouse gases are transported on continental scales.

The Resolved Stellar Population in 50 Regions of M83 from HST/WFC3 Early Release Science Observations

Science.gov (United States)

Kim, Hwihyun; Whitmore, Bradley C.; Chandar, Rupali; Saha, Abhijit; Kaleida, Catherine C.; Mutchler, Max; Cohen, Seth H.; Calzetti, Daniela; O’Connell, Robert W.; Windhorst, Rogier A.;

THE RESOLVED STELLAR POPULATION IN 50 REGIONS OF M83 FROM HST/WFC3 EARLY RELEASE SCIENCE OBSERVATIONS

Energy Technology Data Exchange (ETDEWEB)

Kim, Hwihyun; Cohen, Seth H.; Windhorst, Rogier A. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1404 (United States); Whitmore, Bradley C.; Mutchler, Max; Bond, Howard E. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Chandar, Rupali [Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States); Saha, Abhijit [National Optical Astronomy Observatories, Tucson, AZ 85726-6732 (United States); Kaleida, Catherine C. [Cerro Tololo Inter-American Observatory, La Serena (Chile); Calzetti, Daniela [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); O' Connell, Robert W. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States); Balick, Bruce [Department of Astronomy, University of Washington, Seattle, WA 98195-1580 (United States); Carollo, Marcella [Department of Physics, ETH-Zurich, Zurich 8093 (Switzerland); Disney, Michael J. [School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA (United Kingdom); Dopita, Michael A. [Mount Stromlo and Siding Spring Observatories, Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia); Frogel, Jay A. [Galaxies Unlimited, 1 Tremblant Court, Lutherville, MD 21093 (United States); Hall, Donald N. B. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Holtzman, Jon A. [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States); Kimble, Randy A. [NASA-Goddard Space Flight Center, Greenbelt, MD 20771 (United States); McCarthy, Patrick J., E-mail: hwihyun.kim@asu.edu [Observatories of the Carnegie Institution of Washington, Pasadena, CA 91101-1292 (United States); and others

2012-07-01

We present a multi-wavelength photometric study of {approx}15,000 resolved stars in the nearby spiral galaxy M83 (NGC 5236, D = 4.61 Mpc) based on Hubble Space Telescope Wide Field Camera 3 observations using four filters: F336W, F438W, F555W, and F814W. We select 50 regions (an average size of 260 pc by 280 pc) in the spiral arm and inter-arm areas of M83 and determine the age distribution of the luminous stellar populations in each region. This is accomplished by correcting for extinction toward each individual star by comparing its colors with predictions from stellar isochrones. We compare the resulting luminosity-weighted mean ages of the luminous stars in the 50 regions with those determined from several independent methods, including the number ratio of red-to-blue supergiants, morphological appearance of the regions, surface brightness fluctuations, and the ages of clusters in the regions. We find reasonably good agreement between these methods. We also find that young stars are much more likely to be found in concentrated aggregates along spiral arms, while older stars are more dispersed. These results are consistent with the scenario that star formation is associated with the spiral arms, and stars form primarily in star clusters and then disperse on short timescales to form the field population. The locations of Wolf-Rayet stars are found to correlate with the positions of many of the youngest regions, providing additional support for our ability to accurately estimate ages. We address the effects of spatial resolution on the measured colors, magnitudes, and age estimates. While individual stars can occasionally show measurable differences in the colors and magnitudes, the age estimates for entire regions are only slightly affected.

THE RESOLVED STELLAR POPULATION IN 50 REGIONS OF M83 FROM HST/WFC3 EARLY RELEASE SCIENCE OBSERVATIONS

International Nuclear Information System (INIS)

Kim, Hwihyun; Cohen, Seth H.; Windhorst, Rogier A.; Whitmore, Bradley C.; Mutchler, Max; Bond, Howard E.; Chandar, Rupali; Saha, Abhijit; Kaleida, Catherine C.; Calzetti, Daniela; O'Connell, Robert W.; Balick, Bruce; Carollo, Marcella; Disney, Michael J.; Dopita, Michael A.; Frogel, Jay A.; Hall, Donald N. B.; Holtzman, Jon A.; Kimble, Randy A.; McCarthy, Patrick J.

2012-01-01

We present a multi-wavelength photometric study of ∼15,000 resolved stars in the nearby spiral galaxy M83 (NGC 5236, D = 4.61 Mpc) based on Hubble Space Telescope Wide Field Camera 3 observations using four filters: F336W, F438W, F555W, and F814W. We select 50 regions (an average size of 260 pc by 280 pc) in the spiral arm and inter-arm areas of M83 and determine the age distribution of the luminous stellar populations in each region. This is accomplished by correcting for extinction toward each individual star by comparing its colors with predictions from stellar isochrones. We compare the resulting luminosity-weighted mean ages of the luminous stars in the 50 regions with those determined from several independent methods, including the number ratio of red-to-blue supergiants, morphological appearance of the regions, surface brightness fluctuations, and the ages of clusters in the regions. We find reasonably good agreement between these methods. We also find that young stars are much more likely to be found in concentrated aggregates along spiral arms, while older stars are more dispersed. These results are consistent with the scenario that star formation is associated with the spiral arms, and stars form primarily in star clusters and then disperse on short timescales to form the field population. The locations of Wolf-Rayet stars are found to correlate with the positions of many of the youngest regions, providing additional support for our ability to accurately estimate ages. We address the effects of spatial resolution on the measured colors, magnitudes, and age estimates. While individual stars can occasionally show measurable differences in the colors and magnitudes, the age estimates for entire regions are only slightly affected.

Extreme isolation of WN3/O3 stars and implications for their evolutionary origin as the elusive stripped binaries

Science.gov (United States)

Smith, Nathan; Götberg, Ylva; de Mink, Selma E.

2018-03-01

Recent surveys of the Magellanic Clouds have revealed a subtype of Wolf-Rayet (WR) star with peculiar properties. WN3/O3 spectra exhibit both WR-like emission and O3 V-like absorption - but at lower luminosity than O3 V or WN stars. We examine the projected spatial distribution of WN3/O3 stars in the Large Magellanic Cloud as compared to O-type stars. Surprisingly, WN3/O3 stars are among the most isolated of all classes of massive stars; they have a distribution similar to red supergiants dominated by initial masses of 10-15 M⊙, and are far more dispersed than classical WR stars or luminous blue variables. Their lack of association with clusters of O-type stars suggests strongly that WN3/O3 stars are not the descendants of single massive stars (30 M⊙ or above). Instead, they are likely products of interacting binaries at lower initial mass (10-18 M⊙). Comparison with binary models suggests a probable origin with primaries in this mass range that were stripped of their H envelopes through non-conservative mass transfer by a low-mass secondary. We show that model spectra and positions on the Hertzsprung-Russell diagram for binary-stripped stars are consistent with WN3/O3 stars. Monitoring radial velocities with high-resolution spectra can test for low-mass companions or runaway velocities. With lower initial mass and environments that avoid very massive stars, the WN3/O3 stars fit expectations for progenitors of Type Ib and possibly Type Ibn supernovae.

An electrostatic detector for dust measurement on HT-7 tokamak

International Nuclear Information System (INIS)

Ling, B.L.; Zhang, X.D.; Ti, A.; Gao, X.

2007-01-01

An electrostatic dust detector has been successfully developed to measure dust event in situ and in real time on the HT-7 tokamak. For measuring dust near the edge plasmas and preventing interference of electrons and ions, the shielding plates were designed and installed around the dust detector. The electric signal of dust has been successfully measured during LHCD discharges on HT-7 tokamak. The measured dust signal was in good agreement with bursts appeared on multi-channel H α radiation and on multi-channel ECE diagnostics. Diagnostics of the spectrum and the measurement of impurity emission during dust bursts were studied in detail. It is interesting that there is a delay between dust bursts and CIII line emission. It is observed that the delay time between dust signal and measured CIII line emission is about 0.3 ms in the HT-7 tokamak

New Linear and Star-Shaped Thermogelling Poly([R]-3-hydroxybutyrate) Copolymers.

Science.gov (United States)

Barouti, Ghislaine; Liow, Sing Shy; Dou, Qingqing; Ye, Hongye; Orione, Clément; Guillaume, Sophie M; Loh, Xian Jun

2016-07-18

The synthesis of multi-arm poly([R]-3-hydroxybutyrate) (PHB)-based triblock copolymers (poly([R]-3-hydroxybutyrate)-b-poly(N-isopropylacrylamide)-b-[[poly(methyl ether methacrylate)-g-poly(ethylene glycol)]-co-[poly(methacrylate)-g-poly(propylene glycol)

Design of a multi-arm randomized clinical trial with no control arm.

Science.gov (United States)

Magaret, Amalia; Angus, Derek C; Adhikari, Neill K J; Banura, Patrick; Kissoon, Niranjan; Lawler, James V; Jacob, Shevin T

2016-01-01

Clinical trial designs that include multiple treatments are currently limited to those that perform pairwise comparisons of each investigational treatment to a single control. However, there are settings, such as the recent Ebola outbreak, in which no treatment has been demonstrated to be effective; and therefore, no standard of care exists which would serve as an appropriate control. For illustrative purposes, we focused on the care of patients presenting in austere settings with critically ill 'sepsis-like' syndromes. Our approach involves a novel algorithm for comparing mortality among arms without requiring a single fixed control. The algorithm allows poorly-performing arms to be dropped during interim analyses. Consequently, the study may be completed earlier than planned. We used simulation to determine operating characteristics for the trial and to estimate the required sample size. We present a potential study design targeting a minimal effect size of a 23% relative reduction in mortality between any pair of arms. Using estimated power and spurious significance rates from the simulated scenarios, we show that such a trial would require 2550 participants. Over a range of scenarios, our study has 80 to 99% power to select the optimal treatment. Using a fixed control design, if the control arm is least efficacious, 640 subjects would be enrolled into the least efficacious arm, while our algorithm would enroll between 170 and 430. This simulation method can be easily extended to other settings or other binary outcomes. Early dropping of arms is efficient and ethical when conducting clinical trials with multiple arms. Copyright © 2015 Elsevier Inc. All rights reserved.

Envolvimento de receptores 5-HT2C do hipocampo ventral em comportamentos de defesa de ratos no labirinto em cruz elevado Involvement of ventral hippocampus 5-HT2C receptors on defensive behaviors of rats in the elevated plus-maze

Directory of Open Access Journals (Sweden)

Marília Greidinger Carvalho

2012-04-01

Full Text Available A ativação farmacológica dos receptores 5-HT2C induz comportamentos de defesa em modelos animais. O estudo busca investigar se o bloqueio seletivo de receptores 5-HT2C no hipocampo ventral (HV previne comportamentos defensivos induzidos por um agonista de receptor 5-HT2C administrado perifericamente em ratos expostos ao labirinto em cruz elevado (LCE. Quinze minutos após injeções intraperitoniais (IP, 1ml/kg do agonista 5-HT2C WAY-161503, ratos foram microinjetados bilateralmente no HV com o antagonista seletivo de receptores 5-HT2C SB-242084 (0, 0,1, 0,5 ou 1.5μg. Dez minutos após, cada animal foi exposto ao LCE para o registro de categorias de ansiedade. Injeções sistêmicas do WAY-161503 reduziram seletivamente as explorações nos braços abertos e aumentaram padrões de avaliação de risco. Esse efeito foi atenuado de maneira dose-dependente pela microinjeção de SB-242084 no HV, confirmando a ação ansiogênica de agonistas 5-HT2C e sugerindo que esse perfil comportamental seja mediado, pelo menos em parte, por receptores 5-HT2C do HV.Pharmacological 5-HT2C receptor activation induces defensive behaviors in several animal models of anxiety. The present study investigated whether the selective blockade of 5-HT2C receptors in the ventral hippocampus (VH prevents defensive behaviors induced by a 5-HT2C agonist administered systemically in rats exposed to the elevated plus-maze (EPM. Fifteen minutes after intraperitonial (IP, 1ml/kg injections of the selective 5-HT2C receptor agonist WAY-161503 (3 mg/kg, rats were bilaterally microinjected with the selective 5-HT2C antagonist SB-242084 (0, 0.1, 0.5 or 1.5μg into the VH. Ten minutes after, each animal was exposed to the EPM for measuring classical and ethological anxiety measures. IP WAY-161503 injections selectively decreased open-arm exploration while increasing risk-assessment. This anxiogenic-like action was dose-dependently attenuated by intra-VH SB-242084 microinjections

Single-molecule imaging reveals topological isomer-dependent diffusion by 4-armed star and dicyclic 8-shaped polymers

KAUST Repository

Habuchi, Satoshi; Fujiwara, Susumu; Yamamoto, Takuya; Tezuka, Yasuyuki

2015-01-01

Diffusion dynamics of topological isomers of polymer molecules was investigated at the single-molecule level in a melt state by employing the fluorophore-incorporated 4-armed star and the corresponding doubly-cyclized, 8-shaped poly(THF) chains

Surface modification with MK-2 organic dye in a ZnO/P3HT hybrid solar cell: Impact on device performance

Directory of Open Access Journals (Sweden)

Yu Jin Kim

2014-07-01

Full Text Available The photovoltaic performance of a hybrid ZnO/P3HT heterojunction was improved by modifying the device surface with the MK-2 dye. This organic dye enhanced the compatibility between the polymer and the metal oxide, increased the exciton separation efficiency, and improved the molecular ordering in the charge transport network. The resulting device displayed a substantial enhancement in the photocurrent, open circuit voltage, and fill factor, leading to a 12-fold increase in the power conversion efficiency relative to the unmodified device, from 0.13% to 1.53%.

Quantification of 5-HT{sub 1A} receptors in human brain using p-MPPF kinetic modelling and PET

Energy Technology Data Exchange (ETDEWEB)

Sanabria-Bohorquez, S.M.; Veraart, C. [Neural Rehabilitation Engineering Lab., Univ. Catholique de Louvain, Brussels (Belgium); Biver, F.; Damhaut, P.; Wikler, D.; Goldman, S. [PET/Biomedical Cyclotron Unit, Univ. Libre de Bruxelles (Belgium)

2002-01-01

Serotonin-1A (5-HT{sub 1A}) receptors are implicated in neurochemical mechanisms underlying anxiety and depression and their treatment. Animal studies have suggested that 4-(2'-methoxyphenyl)-1-[2'-[N-(2''-pyridinyl)-p-[{sup 18}F]fluorobenzamido] ethyl] piperazine (p-MPPF) may be a suitable positron emission tomography (PET) tracer of 5-HT{sub 1A} receptors. To test p-MPPF in humans, we performed 60-min dynamic PET scans in 13 healthy volunteers after single bolus injection. Metabolite quantification revealed a fast decrease in tracer plasma concentration, such that at 5 min post injection about 25% of the total radioactivity in plasma corresponded to p-MPPF. Radioactivity concentration was highest in hippocampus, intermediate in neocortex and lowest in basal ganglia and cerebellum. The interactions between p-MPPF and 5-HT{sub 1A} receptors were described using linear compartmental models with plasma input and reference tissue approaches. The two quantification methods provided similar results which are in agreement with previous reports on 5-HT{sub 1A} receptor brain distribution. In conclusion, our results show that p-MPPF is a suitable PET radioligand for 5-HT{sub 1A} receptor human studies. (orig.)

Spectroscopic abundance analyses of the 3He stars HD 185330 and 3 Cen A

Science.gov (United States)

Sadakane, Kozo; Nishimura, Masayoshi

2018-04-01

Abundances of 21 elements in two 3He stars, HD 185330 and 3 Cen A, have been analysed relative to the well-studied sharp-lined B3 V star ι Her. Six elements (P, Ti, Mn, Fe, Ni, and Br) are over-abundant in these two peculiar stars, while six elements (C, O, Mg, Al, S, and Cl) are under-abundant. Absorption lines of the two rarely observed heavy elements Br II and Kr II are detected in both stars and these elements are both over-abundant. The centroid wavelengths of the Ca II infrared triplet lines in these stars are redshifted relative to those lines in ι Her and the presence of heavy isotopes of Ca (mass number 44-46) in these two stars is confirmed. In spite of these similarities, there are several remarkable differences in abundance pattern between these two stars. N is under-abundant in HD 185330, as in many Hg-Mn stars, while it is significantly over-abundant in 3 Cen A. P and Ga are both over-abundant in 3 Cen A, while only P is over-abundant and no trace of absorption line of Ga II can be found in HD 185330. Large over-abundances of Kr and Xe are found in both stars, while the abundance ratio Kr/Xe is significantly different between them (-1.4 dex in HD 185330 and +1.2 dex in 3 Cen A). Some physical explanations are needed to account for these qualitative differences.

CALCULATING THE HABITABLE ZONE OF BINARY STAR SYSTEMS. II. P-TYPE BINARIES

International Nuclear Information System (INIS)

Haghighipour, Nader; Kaltenegger, Lisa

2013-01-01

We have developed a comprehensive methodology for calculating the circumbinary habitable zone (HZ) in planet-hosting P-type binary star systems. We present a general formalism for determining the contribution of each star of the binary to the total flux received at the top of the atmosphere of an Earth-like planet and use the Sun's HZ to calculate the inner and outer boundaries of the HZ around a binary star system. We apply our calculations to the Kepler's currently known circumbinary planetary systems and show the combined stellar flux that determines the boundaries of their HZs. We also show that the HZ in P-type systems is dynamic and, depending on the luminosity of the binary stars, their spectral types, and the binary eccentricity, its boundaries vary as the stars of the binary undergo their orbital motion. We present the details of our calculations and discuss the implications of the results

CALCULATING THE HABITABLE ZONE OF BINARY STAR SYSTEMS. II. P-TYPE BINARIES

Energy Technology Data Exchange (ETDEWEB)

Haghighipour, Nader [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Manoa, Honolulu, HI 96822 (United States); Kaltenegger, Lisa [MPIA, Koenigstuhl 17, Heidelberg, D-69117 (Germany)

2013-11-10

We have developed a comprehensive methodology for calculating the circumbinary habitable zone (HZ) in planet-hosting P-type binary star systems. We present a general formalism for determining the contribution of each star of the binary to the total flux received at the top of the atmosphere of an Earth-like planet and use the Sun's HZ to calculate the inner and outer boundaries of the HZ around a binary star system. We apply our calculations to the Kepler's currently known circumbinary planetary systems and show the combined stellar flux that determines the boundaries of their HZs. We also show that the HZ in P-type systems is dynamic and, depending on the luminosity of the binary stars, their spectral types, and the binary eccentricity, its boundaries vary as the stars of the binary undergo their orbital motion. We present the details of our calculations and discuss the implications of the results.

Impact of 5-HT(3) RA selection within triple antiemetic regimens on uncontrolled highly emetogenic chemotherapy-induced nausea/vomiting.

Science.gov (United States)

Schwartzberg, Lee; Jackson, James; Jain, Gagan; Balu, Sanjeev; Buchner, Deborah

2011-08-01

It is recommended that patients initiate triple antiemetic therapy with one of the 5-hydroxytryptamine receptor antagonists (5-HT(3) RAs), aprepitant (or its intravenous prodrug fosaprepitant) and dexamethasone prior to the start of highly emetogenic chemotherapy (HEC). However, the impact of 5-HT(3) RA selection within triple antiemetic regimens on the risk of uncontrolled chemotherapy-induced nausea and vomiting (CINV) with HEC has not been well studied. To assess the likelihood of an uncontrolled CINV event following antiemetic prophylaxis with the 5-HT(3) RA palonosetron + aprepitant/fosaprepitant + dexamethasone (palonosetron cohort) versus any of the other 5-HT(3) RAs + aprepitant/fosaprepitant + dexamethasone (other 5-HT(3) RA cohort) among single-day HEC cycles. Single-day HEC cycles (a gap of at least 5 days between two administrations) among patients with a cancer diagnosis and receiving antiemetic prophylaxis with the aforementioned regimens between 1/1/2006 and 6/30/2010 were identified from the IMS LifeLink claims database. Uncontrolled CINV events were identified through ICD-9-CM codes (nausea and vomiting), Current Procedural Terminology codes (hydration), rescue medications and/or use of antiemetic therapy from days 2-5 following HEC administration. Risks for an uncontrolled CINV event among all patients, and within breast cancer and multiple cancer subpopulations, were analyzed at cycle level using logistic multivariate regression models. A total of 8018 cycles for the palonosetron cohort and 1926 cycles for the other 5-HT(3) RA cohort (3574 and 978 patients, respectively) were analyzed. Single-day HEC cycles received by the palonosetron cohort had a significantly lower unadjusted risk of an uncontrolled CINV event (17.5 vs 20.7% for the other 5-HT(3) RA cohort; p = 0.0010), with a 17% lower adjusted risk for palonosetron-administered cycles (odds ratio: 0.83; 95% CI: 0.73-0.94; p = 0.0042). Results in the breast cancer and multiple cancer

A new star tracker concept for satellite attitude determination based on a multi-purpose panoramic camera

Science.gov (United States)

Opromolla, Roberto; Fasano, Giancarmine; Rufino, Giancarlo; Grassi, Michele; Pernechele, Claudio; Dionisio, Cesare

2017-11-01

This paper presents an innovative algorithm developed for attitude determination of a space platform. The algorithm exploits images taken from a multi-purpose panoramic camera equipped with hyper-hemispheric lens and used as star tracker. The sensor architecture is also original since state-of-the-art star trackers accurately image as many stars as possible within a narrow- or medium-size field-of-view, while the considered sensor observes an extremely large portion of the celestial sphere but its observation capabilities are limited by the features of the optical system. The proposed original approach combines algorithmic concepts, like template matching and point cloud registration, inherited from the computer vision and robotic research fields, to carry out star identification. The final aim is to provide a robust and reliable initial attitude solution (lost-in-space mode), with a satisfactory accuracy level in view of the multi-purpose functionality of the sensor and considering its limitations in terms of resolution and sensitivity. Performance evaluation is carried out within a simulation environment in which the panoramic camera operation is realistically reproduced, including perturbations in the imaged star pattern. Results show that the presented algorithm is able to estimate attitude with accuracy better than 1° with a success rate around 98% evaluated by densely covering the entire space of the parameters representing the camera pointing in the inertial space.

From Chemotherapy-Induced Emesis to Neuroprotection: Therapeutic Opportunities for 5-HT3 Receptor Antagonists.

Science.gov (United States)

Fakhfouri, Gohar; Mousavizadeh, Kazem; Mehr, Sharam Ejtemaei; Dehpour, Ahmad Reza; Zirak, Mohammad Reza; Ghia, Jean-Eric; Rahimian, Reza

2015-12-01

5-HT3 receptor antagonists are extensively used as efficacious agents in counteracting chemotherapy-induced emesis. Recent investigations have shed light on other potential effects (analgesic, anxiolytic, and anti-psychotic). Some studies have reported neuroprotective properties for the 5-HT3 receptor antagonists in vitro and in vivo. When administered to Aβ-challenged rat cortical neurons, 5-HT3 receptor antagonists substantially abated apoptosis, elevation of cytosolic Ca(2), glutamate release, reactive oxygen species (ROS) generation, and caspase-3 activity. In addition, in vivo studies show that 5-HT3 receptor antagonists possess, alongside their anti-emetic effects, notable immunomodulatory properties in CNS. We found that pretreatment with tropisetron significantly improved neurological deficits and diminished leukocyte transmigration into the brain, TNF-α level, and brain infarction in a murine model of embolic stroke. Our recent investigation revealed that tropisetron protects against Aβ-induced neurotoxicity in vivo through both 5-HT3 receptor-dependent and -independent pathways. Tropisetron, in vitro, was found to be an efficacious inhibitor of the signaling pathway leading to the activation of pro-inflammatory NF-κB, a transcription factor pivotal to the upregulation of several neuroinflammatory mediators in brain. This mini review summarizes novel evidence concerning effects of 5-HT3 antagonists and their possible mechanisms of action in ameliorating neurodegenerative diseases including Alzheimer, multiple sclerosis, and stroke. Further, we discuss some newly synthesized 5-HT3 receptor antagonists with dual properties of 5-HT3 receptor blockade/alpha-7 nicotinic receptor activator and their potential in management of memory impairment. Since 5-HT3 receptor antagonists possess a large therapeutic window, they can constitute a scaffold for design and synthesis of new neuroprotective medications.

The natural triterpene maslinic acid induces apoptosis in HT29 colon cancer cells by a JNK-p53-dependent mechanism

International Nuclear Information System (INIS)

Reyes-Zurita, Fernando J; Pachón-Peña, Gisela; Lizárraga, Daneida; Rufino-Palomares, Eva E; Cascante, Marta; Lupiáñez, José A

2011-01-01

Maslinic acid, a pentacyclic triterpene found in the protective wax-like coating of the leaves and fruit of Olea europaea L., is a promising agent for the prevention of colon cancer. We have shown elsewhere that maslinic acid inhibits cell proliferation to a significant extent and activates mitochondrial apoptosis in colon cancer cells. In our latest work we have investigated further this compound's apoptotic molecular mechanism. We used HT29 adenocarcinoma cells. Changes genotoxicity were analyzed by single-cell gel electrophoresis (comet assay). The cell cycle was determined by flow cytometry. Finally, changes in protein expression were examined by western blotting. Student's t-test was used for statistical comparison. HT29 cells treated with maslinic acid showed significant increases in genotoxicity and cell-cycle arrest during the G0/G1 phase after 72 hours' treatment and an apoptotic sub-G0/G1 peak after 96 hours. Nevertheless, the molecular mechanism for this cytotoxic effect of maslinic acid has never been properly explored. We show here that the anti-tumoral activity of maslinic acid might proceed via p53-mediated apoptosis by acting upon the main signaling components that lead to an increase in p53 activity and the induction of the rest of the factors that participate in the apoptotic pathway. We found that in HT29 cells maslinic acid activated the expression of c-Jun NH2-terminal kinase (JNK), thus inducing p53. Treatment of tumor cells with maslinic acid also resulted in an increase in the expression of Bid and Bax, repression of Bcl-2, release of cytochrome-c and an increase in the expression of caspases -9, -3, and -7. Moreover, maslinic acid produced belated caspase-8 activity, thus amplifying the initial mitochondrial apoptotic signaling. All these results suggest that maslinic acid induces apoptosis in human HT29 colon-cancer cells through the JNK-Bid-mediated mitochondrial apoptotic pathway via the activation of p53. Thus we propose

Tolerance to LSD and DOB induced shaking behaviour: differential adaptations of frontocortical 5-HT(2A) and glutamate receptor binding sites.

Science.gov (United States)

Buchborn, Tobias; Schröder, Helmut; Dieterich, Daniela C; Grecksch, Gisela; Höllt, Volker

2015-03-15

Serotonergic hallucinogens, such as lysergic acid diethylamide (LSD) and dimethoxy-bromoamphetamine (DOB), provoke stereotype-like shaking behaviour in rodents, which is hypothesised to engage frontocortical glutamate receptor activation secondary to serotonin2A (5-HT2A) related glutamate release. Challenging this hypothesis, we here investigate whether tolerance to LSD and DOB correlates with frontocortical adaptations of 5-HT2A and/or overall-glutamate binding sites. LSD and DOB (0.025 and 0.25 mg/kg, i.p.) induce a ketanserin-sensitive (0.5 mg/kg, i.p., 30-min pretreatment) increase in shaking behaviour (including head twitches and wet dog shakes), which with repeated application (7× in 4 ds) is undermined by tolerance. Tolerance to DOB, as indexed by DOB-sensitive [(3)H]spiroperidol and DOB induced [(35)S]GTP-gamma-S binding, is accompanied by a frontocortical decrease in 5-HT2A binding sites and 5-HT2 signalling, respectively; glutamate-sensitive [(3)H]glutamate binding sites, in contrast, remain unchanged. As to LSD, 5-HT2 signalling and 5-HT2A binding, respectively, are not or only marginally affected, yet [(3)H]glutamate binding is significantly decreased. Correlation analysis interrelates tolerance to DOB to the reduced 5-HT2A (r=.80) as well as the unchanged [(3)H]glutamate binding sites (r=.84); tolerance to LSD, as opposed, shares variance with the reduction in [(3)H]glutamate binding sites only (r=.86). Given that DOB and LSD both induce tolerance, one correlating with 5-HT2A, the other with glutamate receptor adaptations, it might be inferred that tolerance can arise at either level. That is, if a hallucinogen (like LSD in our study) fails to induce 5-HT2A (down-)regulation, glutamate receptors (activated postsynaptic to 5-HT2A related glutamate release) might instead adapt and thus prevent further overstimulation of the cortex. Copyright © 2014 Elsevier B.V. All rights reserved.

Impact of 5-HT3 receptor antagonists on chemotherapy-induced nausea and vomiting: a retrospective cohort study.

Science.gov (United States)

Lin, Swu-Jane; Hatoum, Hind T; Buchner, Deborah; Cox, David; Balu, Sanjeev

2012-07-23

1st generation 5-hydroxytryptamine receptor antagonists (5-HT3 RAs), and palonosetron, a 2nd generation 5-HT3 RA, are indicated for the prevention of chemotherapy (CT)-induced nausea and vomiting (CINV) associated with moderately (MEC) and highly emetogenic CT agents (HEC). This study explores the impact of step therapy policies requiring use of an older 5-HT3 RA before palonosetron on risk of CINV associated with hospital or emergency department (ED) admissions. Patients who received cyclophosphamide post breast cancer (BC) surgery or who were diagnosed with lung cancer on carboplatin (LC-carboplatin) or cisplatin (LC-cisplatin) were selected from PharMetrics' (IMS LifeLink) claims dataset (2005-2008). Patients were followed for 6 months from initial CT administration for CINV events identified through ICD-9-CM codes. Patients were grouped into those initiated with older, generic 5-HT3 RAs (ondansetron, granisetron, and dolasetron) and those initiated and maintained on palonosetron throughout study follow-up. CINV events and CINV days were analyzed using multivariate regressions controlling for demographic and clinical variables. Eligible patients numbered 3,606 in BC, 4,497 in LC-carboplatin and 1,154 in LC-cisplatin cohorts, with 52%, 40%, and 34% in the palonosetron group, respectively. There was no significant difference between the two 5-HT3 RA groups in age or Charlson Comorbidity Index among the two MEC cohorts (BC and LC-carboplatin). Among the LC-cisplatin cohort, palonosetron users were older with more males than the older 5-HT3 RA group (age: 60.1 vs. 61.3; males, 66.9% vs. 56.9%). Compared to the older 5-HT3 RAs, the palonosetron groups incurred 22%-51% fewer 5-HT3 RA pharmacy claims, had fewer patients with CINV events (3.5% vs. 5.5% in BC, 9.5% vs. 12.8% in LC-carboplatin, 16.4% vs. 21.7% in LC-cisplatin), and had lower risk for CINV events (odds ratios 0.62, 0.71, or 0.71, respectively; pRAs. Further studies on impact of step therapy policy are

The structural evolution of Milky-Way-like star-forming galaxies since z ∼ 1.3

International Nuclear Information System (INIS)

Patel, Shannon G.; Fumagalli, Mattia; Franx, Marijn; Labbé, Ivo; Muzzin, Adam; Van Dokkum, Pieter G.; Leja, Joel; Skelton, Rosalind E.; Momcheva, Ivelina; Nelson, Erica June; Van der Wel, Arjen; Rix, Hans-Walter; Brammer, Gabriel; Whitaker, Katherine E.; Lundgren, Britt; Wake, David A.; Quadri, Ryan F.

2013-01-01

We follow the structural evolution of star-forming galaxies (SFGs) like the Milky Way by selecting progenitors to z ∼ 1.3 based on the stellar mass growth inferred from the evolution of the star-forming sequence. We select our sample from the 3D-HST survey, which utilizes spectroscopy from the HST/WFC3 G141 near-IR grism and enables precise redshift measurements for our sample of SFGs. Structural properties are obtained from Sérsic profile fits to CANDELS WFC3 imaging. The progenitors of z = 0 SFGs with stellar mass M = 10 10.5 M ☉ are typically half as massive at z ∼ 1. This late-time stellar mass growth is consistent with recent studies that employ abundance matching techniques. The descendant SFGs at z ∼ 0 have grown in half-light radius by a factor of ∼1.4 since z ∼ 1. The half-light radius grows with stellar mass as r e ∝M 0.29 . While most of the stellar mass is clearly assembling at large radii, the mass surface density profiles reveal ongoing mass growth also in the central regions where bulges and pseudobulges are common features in present day late-type galaxies. Some portion of this growth in the central regions is due to star formation as recent observations of Hα maps for SFGs at z ∼ 1 are found to be extended but centrally peaked. Connecting our lookback study with galactic archeology, we find the stellar mass surface density at R = 8 kpc to have increased by a factor of ∼2 since z ∼ 1, in good agreement with measurements derived for the solar neighborhood of the Milky Way.

The NuSTAR Hard X-Ray Survey of the Norma Arm Region

Energy Technology Data Exchange (ETDEWEB)

Fornasini, Francesca M. [Astronomy Department, University of California, 601 Campbell Hall, Berkeley, CA 94720 (United States); Tomsick, John A.; Chiu, Jeng-Lun; Clavel, Maïca; Krivonos, Roman A.; Boggs, Steven E.; Craig, William W. [Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720 (United States); Hong, JaeSub [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Gotthelf, Eric V.; Hailey, Charles J.; Mori, Kaya [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Bauer, Franz; Corral-Santana, Jesús [Instituto de Astrofísica and Centro de Astroingeniería, Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22 (Chile); Rahoui, Farid [European Southern Observatory, K. Schwarzschild-Strasse 2, D-85748 Garching bei München (Germany); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Bodaghee, Arash [Georgia College, 231 W. Hancock Street, Milledgeville, GA 31061 (United States); Alexander, David M. [Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham, DH1 3LE (United Kingdom); Barret, Didier [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France); CNRS, Institut de Recherche en Astrophysique et Planétologie, 9 Av. colonel Roche, BP 44346, F-31028 Toulouse cedex 4 (France); Christensen, Finn E., E-mail: f.fornasini@berkeley.edu [DTU Space—National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); and others

2017-04-01

We present a catalog of hard X-ray sources in a square-degree region surveyed by the Nuclear Spectroscopic Telescope Array ( NuSTAR ) in the direction of the Norma spiral arm. This survey has a total exposure time of 1.7 Ms, and the typical and maximum exposure depths are 50 ks and 1 Ms, respectively. In the area of deepest coverage, sensitivity limits of 5 × 10{sup −14} and 4 × 10{sup −14} erg s{sup −1} cm{sup −2} in the 3–10 and 10–20 keV bands, respectively, are reached. Twenty-eight sources are firmly detected, and 10 are detected with low significance; 8 of the 38 sources are expected to be active galactic nuclei. The three brightest sources were previously identified as a low-mass X-ray binary, high-mass X-ray binary, and pulsar wind nebula. Based on their X-ray properties and multiwavelength counterparts, we identify the likely nature of the other sources as two colliding wind binaries, three pulsar wind nebulae, a black hole binary, and a plurality of cataclysmic variables (CVs). The CV candidates in the Norma region have plasma temperatures of ≈10–20 keV, consistent with the Galactic ridge X-ray emission spectrum but lower than the temperatures of CVs near the Galactic center. This temperature difference may indicate that the Norma region has a lower fraction of intermediate polars relative to other types of CVs compared to the Galactic center. The NuSTAR log N –log S distribution in the 10–20 keV band is consistent with the distribution measured by Chandra at 2–10 keV if the average source spectrum is assumed to be a thermal model with kT  ≈ 15 keV, as observed for the CV candidates.

Photovoltaic cells based on ternary P3HT:PCBM:polymethine dye active layer transparent in the visible range of light

Energy Technology Data Exchange (ETDEWEB)

Bliznyuk, Valery N., E-mail: vblizny@clemson.edu [Department of Materials Science and Engineering, Clemson University, Clemson, SC, 29634 (United States); Gasiorowski, Jacek [Semiconductor Physics, Technische Universität Chemnitz, D-09107 Chemnitz (Germany); Ishchenko, Alexander A.; Bulavko, Gennadiy V. [Institute of Organic Chemistry, National Academy of Sciences of Ukraine, 5 Murmanskaya str., Kiev 02660 (Ukraine); Rahaman, Mahfujur [Semiconductor Physics, Technische Universität Chemnitz, D-09107 Chemnitz (Germany); Hingerl, Kurt [Center for Interface and Nanoanalytics, Johannes Kepler University, Linz 4040 (Austria); Zahn, Dietrich R.T. [Semiconductor Physics, Technische Universität Chemnitz, D-09107 Chemnitz (Germany); Sariciftci, Niyazi S. [Linz Institute for Organic Solar Cells (LIOS), Physical Chemistry, Johannes Kepler University, Linz 4040 (Austria)

2016-12-15

Highlights: • Addition of a polymethine dye to P3HT:PCBM bulk-heterojunction (BHJ) films leads to a compositionally induced transparency in the system. • Variation of the complex refractive index in binary and ternary BHJ films has been studied with spectroscopic ellipsometry. • Power conversion efficiency of ternary BHJ solar cells is determined by the dye composition and photodoping. - Abstract: Optical and photovoltaic properties were studied for ternary photovoltaic cells containing a traditional donor-acceptor bulk-heterojunction (BHJ) active layer modified with polymethine dye molecules in a broad range of compositions and wavelengths. An effect of composition induced optical transparency, due to the strong modification of the density of states, was observed for symmetrical compositions with approximately equal amount of components. Based on our spectroscopic ellipsometry and atomic force microscopy (AFM) studies we can suggest that the variation of the refractive index, which is significantly reduced in the visible range for ternary systems, is involved in the physical mechanism of the phenomenon. Despite of an addition of the IR absorbing component (which allows broadening of the absorption band to up to 800 nm) no improvement in the power conversion efficiency (PCE) is observed in comparison to the binary BHJ system (P3HT:PCBM). Nevertheless, we believe that further advance of the efficiency will be possible if the energy levels will be chemically designed to avoid formation of charge traps at the BHJ interface during light excitation. Such fine adjustment of the system should become possible with a proper choice of polymer:dye composition due to a high versatility of the polymethine dyes demonstrated in previous studies.

High-contrast imaging in multi-star systems: progress in technology development and lab results

Science.gov (United States)

Belikov, Ruslan; Pluzhnik, Eugene; Bendek, Eduardo; Sirbu, Dan

2017-09-01

We present the continued progress and laboratory results advancing the technology readiness of Multi-Star Wavefront Control (MSWC), a method to directly image planets and disks in multi-star systems such as Alpha Centauri. This method works with almost any coronagraph (or external occulter with a DM) and requires little or no change to existing and mature hardware. In particular, it works with single-star coronagraphs and does not require the off-axis star(s) to be coronagraphically suppressed. Because of the ubiquity of multistar systems, this method increases the science yield of many missions and concepts such as WFIRST, Exo-C/S, HabEx, LUVOIR, and potentially enables the detection of Earthlike planets (if they exist) around our nearest neighbor star, Alpha Centauri, with a small and low-cost space telescope such as ACESat. Our lab demonstrations were conducted at the Ames Coronagraph Experiment (ACE) laboratory and show both the feasibility as well as the trade-offs involved in using MSWC. We show several simulations and laboratory tests at roughly TRL-3 corresponding to representative targets and missions, including Alpha Centauri with WFIRST. In particular, we demonstrate MSWC in Super-Nyquist mode, where the distance between the desired dark zone and the off-axis star is larger than the conventional (sub-Nyquist) control range of the DM. Our laboratory tests did not yet include a coronagraph, but did demonstrate significant speckle suppression from two independent light sources at sub- as well as super-Nyquist separations.

Synthesis, characterizations and biocompatibility of novel biodegradable star block copolymers based on poly[(R)-3-hydroxybutyrate] and poly(epsilon-caprolactone)

DEFF Research Database (Denmark)

Wu, Linping; Wang, Liang; Wang, Xiaojuan

2010-01-01

Star block copolymers based on poly[(R)-3-hydroxybutyrate] (PHB) and poly(epsilon-caprolactone) (PCL), termed SPHBCL, were successfully synthesized with structural variation on arm numbers and lengths via coupling reactions and ring opening polymerizations. Arm numbers 3, 4 and 6 of SPHBCL were...... weights of the SPHBCL due to the discrepancy of star copolymer structures. The melting temperature of SPHBCL decreased with increasing degree of branching. Thermal decomposition temperature was revealed to be lower than that of linear block copolymer LPHBCL counterparts based on PHB and PCL. Films made...... from various SPHBCL copolymers had different porous or networking surface morphology, and all possessed improved biocompatibility in terms of less blood clotting and more osteoblast cell growth compared with their corresponding homopolymers PHB and PCL. Among them, it was found, however, that the 4-arm...

Effects of the brain-penetrant and selective 5-HT6 receptor antagonist SB-399885 in animal models of anxiety and depression.

Science.gov (United States)

Wesołowska, Anna; Nikiforuk, Agnieszka

2007-04-01

The effects of a selective 5-HT(6) receptor antagonist, SB-399885 (N-[3,5-dichloro-2-(methoxy)phenyl]-4-(methoxy)-3-(1-piperazinyl)benzenesulfonamide), were evaluated in behavioural tests sensitive to clinically effective anxiolytic- and antidepressant-compounds using diazepam and imipramine as reference drugs. In the Vogel conflict drinking test in rats, SB-399885 (1-3mg/kg i.p.) caused an anxiolytic-like activity comparable to that of diazepam (2.5-5mg/kg i.p.). An anxiolytic-like effect was also seen in the elevated plus-maze test in rats, where SB-399885 (0.3-3mg/kg i.p.) was slightly weaker than diazepam (2.5-5mg/kg i.p.). In the four-plate test in mice, SB-399885 (3-20mg/kg i.p.) showed an anxiolytic-like effect which was weaker than that produced by diazepam (2.5-5mg/kg i.p.). In the forced swim test in rats, SB-399885 (10mg/kg i.p.) significantly shortened the immobility time and the effect was stronger than that of imipramine (30mg/kg i.p.). In the forced swim test in mice, SB-399885 (20-30mg/kg i.p.) had an anti-immobility action, comparable to imipramine (30mg/kg i.p.) and also in the tail suspension test in mice, SB-399885 (10-30mg/kg i.p.) had an antidepressant-like effect, though was weaker than imipramine (10-20mg/kg i.p.). The tested 5-HT(6) antagonist (3-20mg/kg i.p.) shortened the walking time of rats in the open field test and, at a dose of 30mg/kg i.p. reduced the locomotor activity of mice. SB-399885 (in doses up to 30mg/kg i.p.) did not affect motor coordination in mice and rats tested in the rota-rod test. Such data indicate that the selective 5-HT(6) receptor antagonist SB-399885had specific effects, indicative of this compound's anxiolytic and antidepressant potential.

Bioinspired Star-Shaped Poly(l-lysine) Polypeptides: Efficient Polymeric Nanocarriers for the Delivery of DNA to Mesenchymal Stem Cells.

Science.gov (United States)

Walsh, David P; Murphy, Robert D; Panarella, Angela; Raftery, Rosanne M; Cavanagh, Brenton; Simpson, Jeremy C; O'Brien, Fergal J; Heise, Andreas; Cryan, Sally-Ann

2018-05-07

The field of tissue engineering is increasingly recognizing that gene therapy can be employed for modulating in vivo cellular response thereby guiding tissue regeneration. However, the field lacks a versatile and biocompatible gene delivery platform capable of efficiently delivering transgenes to mesenchymal stem cells (MSCs), a cell type often refractory to transfection. Herein, we describe the extensive and systematic exploration of three architectural variations of star-shaped poly(l-lysine) polypeptide (star-PLL) with varying number and length of poly(l-lysine) arms as potential nonviral gene delivery vectors for MSCs. We demonstrate that star-PLL vectors are capable of self-assembling with pDNA to form stable, cationic nanomedicines. Utilizing high content screening, live cell imaging, and mechanistic uptake studies we confirm the intracellular delivery of pDNA by star-PLLs to MSCs is a rapid process, which likely proceeds via a clathrin-independent mechanism. We identify a star-PLL composition with 64 poly(l-lysine) arms and five l-lysine subunits per arm as a particularly efficient vector that is capable of delivering both reporter genes and the therapeutic transgenes bone morphogenetic protein-2 and vascular endothelial growth factor to MSCs. This composition facilitated a 1000-fold increase in transgene expression in MSCs compared to its linear analogue, linear poly(l-lysine). Furthermore, it demonstrated comparable transgene expression to the widely used vector polyethylenimine using a lower pDNA dose with significantly less cytotoxicity. Overall, this study illustrates the ability of the star-PLL vectors to facilitate efficient, nontoxic nucleic acid delivery to MSCs thereby functioning as an innovative nanomedicine platform for tissue engineering applications.

A multi-faceted tailored strategy to implement an electronic clinical decision support system for pressure ulcer prevention in nursing homes: a two-armed randomized controlled trial.

Science.gov (United States)

Beeckman, Dimitri; Clays, Els; Van Hecke, Ann; Vanderwee, Katrien; Schoonhoven, Lisette; Verhaeghe, Sofie

2013-04-01

Frail older people admitted to nursing homes are at risk of a range of adverse outcomes, including pressure ulcers. Clinical decision support systems are believed to have the potential to improve care and to change the behaviour of healthcare professionals. To determine whether a multi-faceted tailored strategy to implement an electronic clinical decision support system for pressure ulcer prevention improves adherence to recommendations for pressure ulcer prevention in nursing homes. Two-armed randomized controlled trial in a nursing home setting in Belgium. The trial consisted of a 16-week implementation intervention between February and June 2010, including one baseline, four intermediate, and one post-testing measurement. Primary outcome was the adherence to guideline-based care recommendations (in terms of allocating adequate pressure ulcer prevention in residents at risk). Secondary outcomes were the change in resident outcomes (pressure ulcer prevalence) and intermediate outcomes (knowledge and attitudes of healthcare professionals). Random sample of 11 wards (6 experimental; 5 control) in a convenience sample of 4 nursing homes in Belgium. In total, 464 nursing home residents and 118 healthcare professionals participated. The experimental arm was involved in a multi-faceted tailored implementation intervention of a clinical decision support system, including interactive education, reminders, monitoring, feedback and leadership. The control arm received a hard-copy of the pressure ulcer prevention protocol, supported by standardized 30 min group lecture. Patients in the intervention arm were significantly more likely to receive fully adequate pressure ulcer prevention when seated in a chair (F=16.4, P=0.003). No significant improvement was observed on pressure ulcer prevalence and knowledge of the professionals. While baseline attitude scores were comparable between both groups [exp. 74.3% vs. contr. 74.5% (P=0.92)], the mean score after the intervention was

Annealing-free P3HT:PCBM-based organic solar cells via two halohydrocarbons additives with similar boiling points

International Nuclear Information System (INIS)

Bao, Xichang; Wang, Ting; Yang, Ailing; Yang, Chunpeng; Dou, Xiaowei; Chen, Weichao; Wang, Ning; Yang, Renqiang

2014-01-01

Highlights: • Two halohydrocarbons were selected as additives for polymer solar cells. • The additives can improve the photocurrent of photovoltaic devices. • Extensive characterization of the blends was done to explore the mechanism. -- Abstract: Efficient annealing-free inverted bulk heterojunction (BHJ) organic solar cells based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C 61 -butyric acid methyl ester (PCBM) (1:1, w/w) have been obtained using two easily accessible halohydrocarbons (1,6-dibromohexane (DBH) and 1-bromodecane (BD)) with the same boiling points as solvent additives. The devices treated with 2.5 wt% additives removed the grain boundary of the large PCBM-rich phase, resulting in more-uniform film morphology on the nanoscale. The more-uniform film morphology greatly improved the short circuit current density of the devices. Finally, PCEs of the devices processed with DBH and BD reached 3.81% and 3.68%, respectively. Both additives with almost the same boiling points had a similar impact on device performance, despite of different chemical structures with different polarities and other physical properties

Initial evaluation of 123I-5-I-R91150, a selective 5-HT2Aligand for single-photon emission tomography, in healthy human subjects

International Nuclear Information System (INIS)

Busatto, G.F.; Pilowsky, L.S.; Costa, D.C.; Mertens, J.; Terriere, D.; Ell, P.J.; Mulligan, R.; Travis, M.J.; Leysen, J.E.; Lui, D.; Gacinovic, S.; Waddington, W.; Lingford-Hughes, A.; Kerwin, R.W.

1997-01-01

The mapping of 5-HT 2 receptors in the brain using functional imaging techniques has been limited by a relative lack of selective radioligands. Iodine-123 labelled 4-amino-N-[1-[3-(4-fluorophenoxy)propyl]-4-methyl-4-piperidinyl]-5-iodo-2-methox ybenzamide ( 123 I-5-I-R91150 or 123 I-R93274) is a new ligand for single-photon emission tomography (SPET), with high affinity and selectivity for 5-HT 2A receptors. This study reports on preliminary 123 I-5-I-R91150 SPET, whole-body and blood distribution findings in five healthy human volunteers. Maximal brain uptake was approximately 2% of total body counts at 180 min post injection (p.i.). Dynamic SPET sequences were acquired with the brain-dedicated, single-slice multi-detector system SME-810 over 200 min p.i. Early peak uptake (at 5 min p.i.) was seen in the cerebellum, a region free from 5HT 2A receptors. In contrast, radioligand binding in the frontal cortex increased steadily over time, up to a peak at approximately 100-120 min p.i. Frontal cortex-cerebellum activity ratios reached values of 1.4, and remained stable from approximately 100 min p.i. onwards. Multi-slice SPET sequences showed a pattern of regional variation of binding compatible with the autoradiographic data on the distribution of 5-HT 2A receptors in humans (cerebral cortex >striatum >cerebellum). These findings suggest that 123 I-5-I-R91150 may be used for the imaging of 5-HT 2A receptors in the living human brain with SPET. (orig.). With 4 figs., 2 tabs

Spectral line survey toward the spiral arm of M51 in the 3 and 2 mm bands

Energy Technology Data Exchange (ETDEWEB)

Watanabe, Yoshimasa; Sakai, Nami; Yamamoto, Satoshi [Department of Physics, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Sorai, Kazuo, E-mail: nabe@taurus.phys.s.u-tokyo.ac.jp [Department of Physics/Department of Cosmoscience, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810 (Japan)

2014-06-10

We have conducted a spectral line survey in the 3 and 2 mm bands toward two positions in a spiral arm of M51 (NGC 5194) with the Institut de Radioastronomie Millimétrique 30 m telescope. In this survey, we have identified 13 molecular species, including CN, CCH, N{sub 2}H{sup +}, HNCO, and CH{sub 3}OH. Furthermore, six isotopologues of the major species have been detected. On the other hand, SiO, HC{sub 3}N, CH{sub 3}CN, and deuterated species such as DCN and DCO{sup +} were not detected. The deuterium fractionation ratios are evaluated to be less than 0.8% and 1.2% for DCN/HCN and DCO{sup +}/HCO{sup +}, respectively. By comparing the results of the two positions with different star formation activities, we have found that the observed chemical compositions do not strongly depend on star formation activities. They seem to reflect a chemical composition averaged over the 1 kpc scale region including many giant molecular clouds. Among the detected molecules CN, CCH, and CH{sub 3}OH are found to be abundant. High abundances of CN and CCH are consistent with the above picture of a widespread distribution of molecules because they can be produced by photodissociation. On the other hand, it seems likely that CH{sub 3}OH is liberated in the gas phase by shocks associated with large-scale phenomena such as cloud-cloud collisions and/or by nonthermal desorption processes such as photoevaporation due to cosmic-ray-induced UV photons. The present result demonstrates a characteristic chemical composition of a giant molecular cloud complex in the spiral arm, which can be used as a standard reference for studying chemistry in active galactic nuclei and starbursts.

Selective labelling of 5-HT{sub 7} receptor recognition sites in rat brain using [{sup 3}H]5-carboxamidotryptamine

Energy Technology Data Exchange (ETDEWEB)

Stowe, R.L.; Barnes, N.M. [Department of Pharmacology, The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

1998-12-01

The aim of the present study was to establish a radioligand binding assay to selectively label the native 5-HT{sub 7} receptor expressed in rat brain. In rat whole brain (minus cerebellum and striatum) homogenate, ({+-})-pindolol (10 {mu}M)-insensitive [{sup 3}H]5-CT ([{sup 3}H]5-carboxamidotryptamine; 0.5 nM) specific binding (defined by 5-HT, 10 {mu}M) displayed a pharmacological profile similar to the recombinant 5-HT{sub 7} receptor, although the Hill coefficients for competition curves generated by methiothepin, ritanserin, sumatriptan, clozapine and pimozide were significantly less than unity. In homogenates of rat hypothalamus, ({+-})-pindolol (10 {mu}M)-insensitive [{sup 3}H]5-CT recognition sites also resembled, pharmacologically, the 5-HT{sub 7} receptor, although pimozide still generated Hill coefficients significantly less than unity. Subsequent studies were performed in the additional presence of WAY100635 (100 nM) to prevent [{sup 3}H]5-CT binding to residual, possibly, 5-HT{sub 1A} sites. Competition for this [{sup 3}H]5-CT binding indicated the labelling in whole rat brain homogenate of a homogenous population of sites with the pharmacological profile of the 5-HT{sub 7} receptor. Saturation studies also indicated that ({+-})-pindolol (10 {mu}M)/WAY 100635 (100 nM)-insensitive [{sup 3}H]5-CT binding to homogenates of whole rat brain was saturable and to an apparently homogenous population of sites which were labelled with nanomolar affinity (B{sub max}=33.2{+-}0.7 fmol mg{sup -1} protein, pK{sub d}=8.78{+-}0.05, mean{+-}S.E.M., n=3). The development of this 5-HT{sub 7} receptor binding assay will aid investigation of the rat native 5-HT{sub 7} receptor. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

The Influences of Arm Resist Motion on a CAR Crash Test Using Hybrid III Dummy with Human-Like Arm

Science.gov (United States)

Kim, Yongchul; Youm, Youngil; Bae, Hanil; Choi, Hyeonki

Safety of the occupant during the crash is very essential design element. Many researches have been investigated in reducing the fatal injury of occupant. They are focusing on the development of a dummy in order to obtain the real human-like motion. However, they have not considered the arm resist motion during the car accident. In this study, we would like to suggest the importance of the reactive force of the arm in a car crash. The influences of reactive force acting on the human upper extremity were investigated using the impedance experimental method with lumped mass model of hand system and a Hybrid III dummy with human-like arm. Impedance parameters (e.g. inertia, spring constant and damping coefficient) of the elbow joint in maximum activation level were measured by free oscillation test using single axis robot. The results showed that without seat belt, the reactive force of human arm reduced the head, chest, and femur injury, and the flexion moment of the neck is higher than that of the conventional dummy.

High-efficiency and air-stable P3HT-based polymer solar cells with a new non-fullerene acceptor

KAUST Repository

Holliday, Sarah

2016-06-09

Solution-processed organic photovoltaics (OPV) offer the attractive prospect of low-cost, light-weight and environmentally benign solar energy production. The highest efficiency OPV at present use low-bandgap donor polymers, many of which suffer from problems with stability and synthetic scalability. They also rely on fullerene-based acceptors, which themselves have issues with cost, stability and limited spectral absorption. Here we present a new non-fullerene acceptor that has been specifically designed to give improved performance alongside the wide bandgap donor poly(3-hexylthiophene), a polymer with significantly better prospects for commercial OPV due to its relative scalability and stability. Thanks to the well-matched optoelectronic and morphological properties of these materials, efficiencies of 6.4% are achieved which is the highest reported for fullerene-free P3HT devices. In addition, dramatically improved air stability is demonstrated relative to other high-efficiency OPV, showing the excellent potential of this new material combination for future technological applications.

Functionalized carbon nanotube doping of P3HT:PCBM photovoltaic devices for enhancing short circuit current and efficiency

Directory of Open Access Journals (Sweden)

Rohit Bhatia

2017-03-01

Full Text Available We have successfully functionalized multiwalled carbon nanotubes (MWCNTs using nitrene approach employing the two aryl azides as a precursor for nitrene generation. The dispersion of functionalized MWCNTs has been enhanced in various organic solvents. These functionalized MWCNTs have been successfully doped in various concentrations in the bulk heterojunction (BHJ organic photovoltaic (OPV cells with a poly (3-hexyl thiophene (P3HT and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM photoactive blended layer. The incorporation of MWCNTs with aryl functional groups, in active the layer, results in enhanced performance with respect to a reference cell. The maximum power conversion efficiency of 1.86% is achieved with adduct I while in the case of adduct II it gets double to 2.0% in comparison with a reference cell. This improvement in the device performance is attributed to enhanced exciton dissociation and improved charge transport properties due to the formation of a nanotube percolation network in the photoactive composite layer.

High-efficiency and air-stable P3HT-based polymer solar cells with a new non-fullerene acceptor

Science.gov (United States)

Holliday, Sarah; Ashraf, Raja Shahid; Wadsworth, Andrew; Baran, Derya; Yousaf, Syeda Amber; Nielsen, Christian B.; Tan, Ching-Hong; Dimitrov, Stoichko D.; Shang, Zhengrong; Gasparini, Nicola; Alamoudi, Maha; Laquai, Frédéric; Brabec, Christoph J.; Salleo, Alberto; Durrant, James R.; McCulloch, Iain

2016-01-01

Solution-processed organic photovoltaics (OPV) offer the attractive prospect of low-cost, light-weight and environmentally benign solar energy production. The highest efficiency OPV at present use low-bandgap donor polymers, many of which suffer from problems with stability and synthetic scalability. They also rely on fullerene-based acceptors, which themselves have issues with cost, stability and limited spectral absorption. Here we present a new non-fullerene acceptor that has been specifically designed to give improved performance alongside the wide bandgap donor poly(3-hexylthiophene), a polymer with significantly better prospects for commercial OPV due to its relative scalability and stability. Thanks to the well-matched optoelectronic and morphological properties of these materials, efficiencies of 6.4% are achieved which is the highest reported for fullerene-free P3HT devices. In addition, dramatically improved air stability is demonstrated relative to other high-efficiency OPV, showing the excellent potential of this new material combination for future technological applications. PMID:27279376

High-efficiency and air-stable P3HT-based polymer solar cells with a new non-fullerene acceptor

KAUST Repository

Holliday, Sarah; Ashraf, Raja Shahid; Wadsworth, Andrew; Baran, Derya; Yousaf, Syeda Amber; Nielsen, Christian B.; Tan, Ching-Hong; Dimitrov, Stoichko D.; Shang, Zhengrong; Gasparini, Nicola; Alamoudi, Maha; Laquai, Fré dé ric; Brabec, Christoph J.; Salleo, Alberto; Durrant, James R.; McCulloch, Iain

2016-01-01

Solution-processed organic photovoltaics (OPV) offer the attractive prospect of low-cost, light-weight and environmentally benign solar energy production. The highest efficiency OPV at present use low-bandgap donor polymers, many of which suffer from problems with stability and synthetic scalability. They also rely on fullerene-based acceptors, which themselves have issues with cost, stability and limited spectral absorption. Here we present a new non-fullerene acceptor that has been specifically designed to give improved performance alongside the wide bandgap donor poly(3-hexylthiophene), a polymer with significantly better prospects for commercial OPV due to its relative scalability and stability. Thanks to the well-matched optoelectronic and morphological properties of these materials, efficiencies of 6.4% are achieved which is the highest reported for fullerene-free P3HT devices. In addition, dramatically improved air stability is demonstrated relative to other high-efficiency OPV, showing the excellent potential of this new material combination for future technological applications.

5-HT3A -driven green fluorescent protein delineates gustatory fibers innervating sour-responsive taste cells: A labeled line for sour taste?

Science.gov (United States)

Stratford, J M; Larson, E D; Yang, R; Salcedo, E; Finger, T E

2017-07-01

Taste buds contain multiple cell types with each type expressing receptors and transduction components for a subset of taste qualities. The sour sensing cells, Type III cells, release serotonin (5-HT) in response to the presence of sour (acidic) tastants and this released 5-HT activates 5-HT 3 receptors on the gustatory nerves. We show here, using 5-HT 3A GFP mice, that 5-HT 3 -expressing nerve fibers preferentially contact and receive synaptic contact from Type III taste cells. Further, these 5-HT 3 -expressing nerve fibers terminate in a restricted central-lateral portion of the nucleus of the solitary tract (nTS)-the same area that shows increased c-Fos expression upon presentation of a sour tastant (30 mM citric acid). This acid stimulation also evokes c-Fos in the laterally adjacent mediodorsal spinal trigeminal nucleus (DMSp5), but this trigeminal activation is not associated with the presence of 5-HT 3 -expressing nerve fibers as it is in the nTS. Rather, the neuronal activation in the trigeminal complex likely is attributable to direct depolarization of acid-sensitive trigeminal nerve fibers, for example, polymodal nociceptors, rather than through taste buds. Taken together, these findings suggest that transmission of sour taste information involves communication between Type III taste cells and 5-HT 3 -expressing afferent nerve fibers that project to a restricted portion of the nTS consistent with a crude mapping of taste quality information in the primary gustatory nucleus. © 2017 Wiley Periodicals, Inc.

Chemical Compositions of Young Stars in the Leading Arm of the Magellanic System

Science.gov (United States)

Zhang, L.; Moni Bidin, C.; Casetti-Dinescu, D. I.; Mendez, R. A.; Girard, T. M.; Korchagin, V. I.; Vieira, K.; van Altena, W. F.; Zhao, G.

2017-07-01

Seven element abundances (He, C, N, O, Mg, Si, and S) and kinematics were determined for eight O-/B- type stars, based on high resolution spectra taken with the MIKE instrument on the Magellan 6.5m Clay telescope (program ID: CN2014A-057). The sample is selected from 42 candidates Casetti-Dinescu et al.(2014, ApJL, 784, L37) of membership in the Leading Arm (LA) of the Magellanic System. After investigating the relationship between abundances and kinematics parameters, we found that five stars have kinematics compatible with LA membership, i.e. RV>100kms-1. For the five possible LA member stars, Mg abundance is significantly lower than that of the remaining two that are kinematical members of the Galactic disk, and is more close to the LMC values. Distances to the LA members indicate that they are at the edge of the Galactic disk, while ages are of the order of ˜ 50-70 Myr, lower than the dynamical age of the LA, suggesting a single star-forming episode in the LA. VLSR of the LA members decreases with decreasing Magellanic longitude, confirming the results of previous LA gas studies (McClure-Griffiths et al.2008, ApJ, 673, L143). Our abundance and kinematic results for the LA member stars demonstrate that parts of the LA are hydrodynamically interacting with the gaseous Galactic disk, forming young stars that are chemically distinct from those in the Galactic disk. These results can provide constraints to future models for the Magellanic leading material.

Osmotic pressure and virial coefficients of star and comb polymer solutions: dissipative particle dynamics.

Science.gov (United States)

Wang, Tzu-Yu; Fang, Che-Ming; Sheng, Yu-Jane; Tsao, Heng-Kwong

2009-03-28

The effects of macromolecular architecture on the osmotic pressure pi and virial coefficients (B(2) and B(3)) of star and comb polymers in good solvents are studied by dissipative particle dynamics simulations for both dilute and semiconcentrated regimes. The dependence of the osmotic pressure on polymer concentration is directly calculated by considering two reservoirs separated by a semipermeable, fictitious membrane. Our simulation results show that the ratios A(n+1) identical with B(n+1)/R(g)(3n) are essentially constant and A(2) and A(3) are arm number (f) dependent, where R(g) is zero-density radius of gyration. The value of dimensionless virial ratio g = A(3)/A(2)(2) increases with arm number of stars whereas it is essentially arm number independent for comb polymers. In semiconcentrated regime the scaling relation between osmotic pressure and volume fraction, pi proportional to phi(lambda), still holds for both star and comb polymers. For comb polymers, the exponent lambda is close to lambda(*) (approximately = 2.73 for linear chains) and is independent of the arm number. However, for star polymers, the exponent lambda deviates from lambda(*) and actually grows with increasing the arm number. This may be attributed to the significant ternary interactions near the star core in the many-arm systems.

Seismology of rapidly rotating and solar-like stars

Science.gov (United States)

Reese, Daniel Roy

2018-05-01

A great deal of progress has been made in stellar physics thanks to asteroseismology, the study of pulsating stars. Indeed, asteroseismology is currently the only way to probe the internal structure of stars. The work presented here focuses on some of the theoretical aspects of this domain and addresses two broad categories of stars, namely solar-like pulsators (including red giants), and rapidly rotating pulsating stars. The work on solar-like pulsators focuses on setting up methods for efficiently characterising a large number of stars, in preparation for space missions like TESS and PLATO 2.0. In particular, the AIMS code applies an MCMC algorithm to find stellar properties and a sample of stellar models which fit a set of seismic and classic observational constraints. In order to reduce computation time, this code interpolates within a precalculated grid of models, using a Delaunay tessellation which allows a greater flexibility on the construction of the grid. Using interpolated models based on the outputs from this code or models from other forward modelling codes, it is possible to obtain refined estimates of various stellar properties such as the mean density thanks to inversion methods put together by me and G. Buldgen, my former PhD student. Finally, I show how inversion-type methods can also be used to test more qualitative information such as whether a decreasing rotation profile is compatible with a set of observed rotational splittings and a given reference model. In contrast to solar-like pulsators, the pulsation modes of rapidly rotating stars remain much more difficult to interpret due to the complexity of the numerical calculations needed to calculate such modes, the lack of simple frequency patterns, and the fact that it is difficult to predict mode amplitudes. The work described here therefore focuses on addressing the above difficulties one at a time in the hopes that it will one day be possible to carry out detailed asteroseismology in these

Conformational and Structural Properties of High Functionality Dendrimer-like Star Polymers Synthesized from Living Polymerization Techniques; TOPICAL

International Nuclear Information System (INIS)

Pople, John A.

2001-01-01

The design, synthesis and solution properties of dendritic-linear hybrid macromolecules is described. The synthetic strategy employs living ring-opening polymerization in combination with selective and quantitative organic transformations for the preparation of new molecular architectures similar to classical star polymers and dendrimers. The polymers were constructed from high molecular weight poly(e-caprolactone) initiated from the surface hydroxyl groups of dendrimers derived from bis(hydroxymethyl) propionic acid (bis-MPA) in the presence of stannous 2-ethyl hexanoate (Sn(Oct)2). In this way, star and hyperstar poly(e-caprolactones) were elaborated depending on the generation of dendrimer employed. The ROP from these hydroxy groups was found to be a facile process leading to controlled molecular weight, low dispersity products (Mw/Mn) and lt; 1.15. In addition to the use of dendrimers as building blocks to star polymers, functional dendrons derived from bis-MPA were attached to chain ends of the star polymers, yielding structures that closely resemble that of the most advanced dendrimers. Measurements of the solution properties (hydrodynamic volume vs. molecular weight) on the dendritic-linear hybrids show a deviation from linearity, with a lower than expected hydrodynamic volume, analogous to the solution properties of dendrimers of high generation number. The onset of the deviation begins with the polymers initiated from the second generation dendrimer of bis-MPA and becomes more exaggerated with the higher generations. It was found that polymerization amplifies the nonlinear solution behavior of dendrimers. Small angle neutron scattering (SANS) measurements revealed that the radius of gyration scaled with arm functionality (f) as f 2/3, in accordance with the Daoud-Cotton model for many arm star polymer

High-resolution imaging of brain 5-HT{sub 1B} receptors in the rhesus monkey using [{sup 11}C]P943

Energy Technology Data Exchange (ETDEWEB)

Nabulsi, Nabeel; Huang Yiyun; Weinzimmer, David; Ropchan, Jim; Frost, James J. [Yale PET Center, Department of Diagnostic Radiology and Psychiatry, Yale University School of Medicine, P.O. Box 208048, New Haven, CT 06520-8048 (United States); McCarthy, Timothy [Pfizer Global R and D, Groton, CT 06340 (United States); Carson, Richard E.; Ding Yushin [Yale PET Center, Department of Diagnostic Radiology and Psychiatry, Yale University School of Medicine, P.O. Box 208048, New Haven, CT 06520-8048 (United States)

2010-02-15

The serotonin 5-HT{sub 1B} receptors regulate the release of serotonin and are involved in various disease states, including depression and schizophrenia. The goal of the study was to evaluate a high affinity and high selectivity antagonist, [{sup 11}C]P943, as a positron emission tomography (PET) tracer for imaging the 5-HT{sub 1B} receptor. [{sup 11}C]P943 was synthesized via N-methylation of the precursor with [{sup 11}C]methyl iodide or [{sup 11}C]methyl triflate using automated modules. The average radiochemical yield was approx. 10% with radiochemical purity of >99% and specific activity of 8.8{+-}3.6 mCi/nmol at the end-of-synthesis (n=37). PET imaging was performed in non-human primates with a high-resolution research tomograph scanner with a bolus/infusion paradigm. Binding potential (BP{sub ND}) was calculated using the equilibrium ratios of regions to cerebellum. The tracer uptake was highest in the globus pallidus and occipital cortex, moderate in basal ganglia and thalamus, and lowest in the cerebellum, which is consistent with the known brain distribution of 5-HT{sub 1B} receptors. Infusion of tracer at different specific activities (by adding various amount of unlabeled P943) reduced BP{sub ND} values in a dose-dependent manner, demonstrating the saturability of the tracer binding. Blocking studies with GR127935 (2 mg/kg iv), a selective 5-HT{sub 1B}/5-HT{sub 1D} antagonist, resulted in reduction of BP{sub ND} values by 42-95% across regions; for an example, in occipital region from 0.71 to 0.03, indicating a complete blockade. These results demonstrate the saturability and specificity of [{sup 11}C]P943 for 5-HT{sub 1B} receptors, suggesting its suitability as a PET radiotracer for in vivo evaluations of the 5-HT{sub 1B} receptor system in humans.

The spiral arms of the Milky Way: The relative location of each different arm tracer within a typical spiral arm width

Energy Technology Data Exchange (ETDEWEB)

Vallée, Jacques P., E-mail: jacques.vallee@nrc-cnrc.gc.ca [National Research Council Canada, National Science Infrastructure portfolio, Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, B.C., V9E 2E7 (Canada)

2014-07-01

From the Sun's location in the Galactic disk, different arm tracers (CO, H I, hot dust, etc.) have been employed to locate a tangent to each spiral arm. Using all various and different observed spiral arm tracers (as published elsewhere), we embark on a new goal, namely the statistical analysis of these published data (data mining) to statistically compute the mean location of each spiral arm tracer. We show for a typical arm cross-cut, a separation of 400 pc between the mid-arm and the dust lane (at the inner edge of the arm, toward the Galactic center). Are some arms major and others minor? Separating arms into two sets, as suggested by some, we find the same arm widths between the two sets. Our interpretation is that we live in a multiple (four-arm) spiral (logarithmic) pattern (around a pitch angle of 12°) for the stars and gas in the Milky Way, with a sizable interarm separation (around 3 kpc) at the Sun's location and the same arm width for each arm (near 400 pc from mid-arm to dust lane).

The spiral arms of the Milky Way: The relative location of each different arm tracer within a typical spiral arm width

International Nuclear Information System (INIS)

Vallée, Jacques P.

2014-01-01

From the Sun's location in the Galactic disk, different arm tracers (CO, H I, hot dust, etc.) have been employed to locate a tangent to each spiral arm. Using all various and different observed spiral arm tracers (as published elsewhere), we embark on a new goal, namely the statistical analysis of these published data (data mining) to statistically compute the mean location of each spiral arm tracer. We show for a typical arm cross-cut, a separation of 400 pc between the mid-arm and the dust lane (at the inner edge of the arm, toward the Galactic center). Are some arms major and others minor? Separating arms into two sets, as suggested by some, we find the same arm widths between the two sets. Our interpretation is that we live in a multiple (four-arm) spiral (logarithmic) pattern (around a pitch angle of 12°) for the stars and gas in the Milky Way, with a sizable interarm separation (around 3 kpc) at the Sun's location and the same arm width for each arm (near 400 pc from mid-arm to dust lane).

Effects of a 5-HT3 agonist and antagonist on inter-male aggression in Mus musculus

Directory of Open Access Journals (Sweden)

Michael Kerchner

2006-01-01

Full Text Available Research has revealed an inverse relationship between serotonin (5-HT levels in the brain and aggressive behavior. However, effects on aggression at the level of the receptor have yet to be elucidated for many 5-HT receptor subtypes. This study examined the effects of the 5-HT3 receptor agonist m-chlorophenylbiguanide (mCPBG and antagonist ondansetron on inter-male aggression in mice. Using a resident-intruder paradigm designed to assess both offensive and defensive aggression, male C57BL/6J mice received 1 mg/kg i.p. injections of either mCPBG, ondansetron, or an inactive vehicle and were subsequently exposed to male AKR/J mice for a period of 10 minutes. Attack latency and the proportion of time engaged in a range of defensive behaviors were recorded. Subject C57BL/6J mice were then immediately run in an open field test for an additional 10 minutes to examine any anxiolytic or sedative effects of the drugs. Results show no significant differences between drug groups in either offensive or defensive behavior. No significant differences were observed between drug groups and open field activity; however, significant differences were seen between the offensive and defensive condition in the open field. In conclusion, this study fails to reveal any significant effects of the 5-HT3 agents on inter-male aggression, which may reflect a functional difference between the 5-HT3 receptor and the remaining G-protein coupled 5-HT receptor. However, this conclusion is limited by the large variance in behavior combined with small sample sizes, or the possibility of a drug dose insufficient for behavioral effects.

Fe3O4 nanoparticles modified by CD-containing star polymer for MRI and drug delivery.

Science.gov (United States)

Cha, Ruitao; Li, Juanjuan; Liu, Yang; Zhang, Yifan; Xie, Qian; Zhang, Mingming

2017-10-01

Fe 3 O 4 nanoparticles with ultrasmall sizes show good T 1 or T 1 +T 2 contrast abilities, and have attracted considerable interest in the field of magnetic resonance imaging (MRI) contrast agents. For effective biomedical applications, the colloidal stability and biocompatibility of the Fe 3 O 4 nanoparticles need to be improved without reducing MRI relaxivity. In this paper, star polymers were used as coating materials to modify Fe 3 O 4 nanoparticles in view of their dense molecular architecture with moderate flexibility. The star polymer was composed of a β-cyclodextrin (β-CD) core and poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA) arms. Meanwhile, reduced glutathione (GSH), as a model drug, was also associated with the star polymer. Thus, a new platform for simultaneous diagnosis and treatment was achieved. Compared to the Fe 3 O 4 nanoparticles coated with linear polymers, the Fe 3 O 4 nanoparticles coated with star polymers (Fe 3 O 4 @GCP) possessed higher GSH association capacity and better stability in serum-containing solution. GSH could be released from Fe 3 O 4 @GCP nanoparticles in response to pH value of the solution. Since the sulfhydryl group on GSH is able to combine free radicals, Fe 3 O 4 @GCP nanoparticles exhibited less cytotoxicity compared to the Fe 3 O 4 nanoparticles without including GSH. Furthermore, the nanoparticles could also serve as good T 1 MRI contrast agent, and the MRI relaxivity of Fe 3 O 4 @GCP nanoparticles did not decrease after coated with the star polymer. These results indicate that the precisely designed Fe 3 O 4 @GCP nanoparticles could be used as a versatile promising theranostic nano-platform. Copyright © 2017 Elsevier B.V. All rights reserved.

The Perseus arm in the anticenter direction

Science.gov (United States)

Monguió, M.; Grosbøl, P.; Figueras, F.

2015-05-01

The stellar overdensity due to the Perseus arm has been detected in the anticenter direction through individual field stars. For that purpose, a Str&{uml;o}mgren photometric survey covering 16° ^2 was developed with the Wide Field Camera at the Isaac Newton Telescope. This photometry allowed us to compute individual physical parameters for these stars using a new method based on atmospheric models and evolutionary tracks. The analysis of the surface density as a function of distance for intermediate young stars in this survey allowed us to detect an overdensity at 1.6±0.2 kpc from the Sun, that can be associated with the Perseus arm, with a surface density amplitude of ˜14%. The significance of the detection is above 4σ for all the cases. The fit for the radial scale length of the Galactic disk provided values in the range [2.9,3.5] kpc for the population of the B4-A1 stars. We also analyzed the interstellar visual absorption distribution, and its variation as a function of distance is coherent with a dust layer before the Perseus arm location.

MDMA self-administration fails to alter the behavioral response to 5-HT(1A) and 5-HT(1B) agonists.

Science.gov (United States)

Aronsen, Dane; Schenk, Susan

2016-04-01

Regular use of the street drug, ecstasy, produces a number of cognitive and behavioral deficits. One possible mechanism for these deficits is functional changes in serotonin (5-HT) receptors as a consequence of prolonged 3,4 methylenedioxymethamphetamine (MDMA)-produced 5-HT release. Of particular interest are the 5-HT(1A) and 5-HT(1B) receptor subtypes since they have been implicated in several of the behaviors that have been shown to be impacted in ecstasy users and in animals exposed to MDMA. This study aimed to determine the effect of extensive MDMA self-administration on behavioral responses to the 5-HT(1A) agonist, 8-hydroxy-2-(n-dipropylamino)tetralin (8-OH-DPAT), and the 5-HT(1B/1A) agonist, RU 24969. Male Sprague-Dawley rats self-administered a total of 350 mg/kg MDMA, or vehicle, over 20-58 daily self-administration sessions. Two days after the last self-administration session, the hyperactive response to 8-OH-DPAT (0.03-1.0 mg/kg) or the adipsic response to RU 24969 (0.3-3.0 mg/kg) were assessed. 8-OH-DPAT dose dependently increased horizontal activity, but this response was not altered by MDMA self-administration. The dose-response curve for RU 24969-produced adipsia was also not altered by MDMA self-administration. Cognitive and behavioral deficits produced by repeated exposure to MDMA self-administration are not likely due to alterations in 5-HT(1A) or 5-HT(1B) receptor mechanisms.

OBSERVATIONS OF INTENSITY FLUCTUATIONS ATTRIBUTED TO GRANULATION AND FACULAE ON SUN-LIKE STARS FROM THE KEPLER MISSION

Energy Technology Data Exchange (ETDEWEB)

Karoff, C. [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Campante, T. L. [Centro de Astrofisica and Faculdade de Ciencias, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Ballot, J. [CNRS, Institut de Recherche en Astrophysique et Planetologie, 14 avenue Edouard Belin, F-31400, Toulouse (France); Kallinger, T. [Instituut voor Sterrenkunde, K. U. Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Gruberbauer, M. [Institute for Computational Astrophysics, Department of Astronomy and Physics, Saint Mary' s University, B3H 3C3 Halifax (Canada); Garcia, R. A. [Laboratoire AIM, CEA/DSM-CNRS-Universit Paris Diderot, IRFU/SAp, Centre de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Caldwell, D. A.; Christiansen, J. L. [SETI Institute/NASA Ames Research Center, Moffett Field, CA 94035 (United States); Kinemuchi, K., E-mail: karoff@phys.au.dk [Bay Area Environmental Research Inst./NASA Ames Research Center, Moffett Field, CA 94035 (United States)

2013-04-10

Sun-like stars show intensity fluctuations on a number of timescales due to various physical phenomena on their surfaces. These phenomena can convincingly be studied in the frequency spectra of these stars-while the strongest signatures usually originate from spots, granulation, and p-mode oscillations, it has also been suggested that the frequency spectrum of the Sun contains a signature of faculae. We have analyzed three stars observed for 13 months in short cadence (58.84 s sampling) by the Kepler mission. The frequency spectra of all three stars, as for the Sun, contain signatures that we can attribute to granulation, faculae, and p-mode oscillations. The temporal variability of the signatures attributed to granulation, faculae, and p-mode oscillations was analyzed and the analysis indicates a periodic variability in the granulation and faculae signatures-comparable to what is seen in the Sun.

Glucose-dependent trafficking of 5-HT3 receptors in rat gastrointestinal vagal afferent neurons

Science.gov (United States)

Babic, Tanja; Troy, Amanda E; Fortna, Samuel R; Browning, Kirsteen N

2012-01-01

Background Intestinal glucose induces gastric relaxation via vagally mediated sensory-motor reflexes. Glucose can alter the activity of gastrointestinal (GI) vagal afferent (sensory) neurons directly, via closure of ATP-sensitive potassium channels, as well as indirectly, via the release of 5-hydroxytryptamine (5-HT) from mucosal enteroendocrine cells. We hypothesized that glucose may also be able to modulate the ability of GI vagal afferent neurons to respond to the released 5-HT, via regulation of neuronal 5-HT3 receptors. Methods Whole cell patch clamp recordings were made from acutely dissociated GI-projecting vagal afferent neurons exposed to equiosmolar Krebs’ solution containing different concentrations of D-glucose (1.25–20mM) and the response to picospritz application of 5-HT assessed. The distribution of 5-HT3 receptors in neurons exposed to different glucose concentrations was also assessed immunohistochemically. Key Results Increasing or decreasing extracellular D-glucose concentration increased or decreased, respectively, the 5-HT-induced inward current as well as the proportion of 5-HT3 receptors associated with the neuronal membrane. These responses were blocked by the Golgi-disrupting agent Brefeldin-A (5µM) suggesting involvement of a protein trafficking pathway. Furthermore, L-glucose did not mimic the response of D-glucose implying that metabolic events downstream of neuronal glucose uptake are required in order to observe the modulation of 5-HT3 receptor mediated responses. Conclusions & Inferences These results suggest that, in addition to inducing the release of 5-HT from enterochromaffin cells, glucose may also increase the ability of GI vagal sensory neurons to respond to the released 5-HT, providing a means by which the vagal afferent signal can be amplified or prolonged. PMID:22845622

Erinacine A-Enriched Hericium erinaceus Mycelium Produces Antidepressant-Like Effects through Modulating BDNF/PI3K/Akt/GSK-3β Signaling in Mice.

Science.gov (United States)

Chiu, Chun-Hung; Chyau, Charng-Cherng; Chen, Chin-Chu; Lee, Li-Ya; Chen, Wan-Ping; Liu, Jia-Ling; Lin, Wen-Hsin; Mong, Mei-Chin

2018-01-24

Antidepressant-like effects of ethanolic extract of Hericium erinaceus (HE) mycelium enriched in erinacine A on depressive mice challenged by repeated restraint stress (RS) were examined. HE at 100, 200 or 400 mg/kg body weight/day was orally given to mice for four weeks. After two weeks of HE administration, all mice except the control group went through with 14 days of RS protocol. Stressed mice exhibited various behavioral alterations, such as extending immobility time in the tail suspension test (TST) and forced swimming test (FST), and increasing the number of entries in open arm (POAE) and the time spent in the open arm (PTOA). Moreover, the levels of norepinephrine (NE), dopamine (DA) and serotonin (5-HT) were decreased in the stressed mice, while the levels of interleukin (IL)-6 and tumor necrosis factor (TNF)-α were increased. These changes were significantly inverted by the administration of HE, especially at the dose of 200 or 400 mg/kg body weight/day. Additionally, HE was shown to activate the BDNF/TrkB/PI3K/Akt/GSK-3β pathways and block the NF-κB signals in mice. Taken together, erinacine A-enriched HE mycelium could reverse the depressive-like behavior caused by RS and was accompanied by the modulation of monoamine neurotransmitters as well as pro-inflammatory cytokines, and regulation of BDNF pathways. Therefore, erinacine A-enriched HE mycelium could be an attractive agent for the treatment of depressive disorders.

Erinacine A-Enriched Hericium erinaceus Mycelium Produces Antidepressant-Like Effects through Modulating BDNF/PI3K/Akt/GSK-3β Signaling in Mice

Directory of Open Access Journals (Sweden)

Chun-Hung Chiu

2018-01-01

Full Text Available Antidepressant-like effects of ethanolic extract of Hericium erinaceus (HE mycelium enriched in erinacine A on depressive mice challenged by repeated restraint stress (RS were examined. HE at 100, 200 or 400 mg/kg body weight/day was orally given to mice for four weeks. After two weeks of HE administration, all mice except the control group went through with 14 days of RS protocol. Stressed mice exhibited various behavioral alterations, such as extending immobility time in the tail suspension test (TST and forced swimming test (FST, and increasing the number of entries in open arm (POAE and the time spent in the open arm (PTOA. Moreover, the levels of norepinephrine (NE, dopamine (DA and serotonin (5-HT were decreased in the stressed mice, while the levels of interleukin (IL-6 and tumor necrosis factor (TNF-α were increased. These changes were significantly inverted by the administration of HE, especially at the dose of 200 or 400 mg/kg body weight/day. Additionally, HE was shown to activate the BDNF/TrkB/PI3K/Akt/GSK-3β pathways and block the NF-κB signals in mice. Taken together, erinacine A-enriched HE mycelium could reverse the depressive-like behavior caused by RS and was accompanied by the modulation of monoamine neurotransmitters as well as pro-inflammatory cytokines, and regulation of BDNF pathways. Therefore, erinacine A-enriched HE mycelium could be an attractive agent for the treatment of depressive disorders.

Mechanosensory Signaling in Enterochromaffin Cells and 5-HT Release: Potential Implications for Gut Inflammation

Directory of Open Access Journals (Sweden)

Andromeda Linan Rico

2016-12-01

Full Text Available Enterochromaffin cells (EC synthesize 95% of the body 5-HT and release 5-HT in response to mechanical or chemical stimulation. EC cell 5-HT has physiological effects on gut motility, secretion and visceral sensation. Abnormal regulation of 5-HT occurs in gastrointestinal disorders and Inflammatory Bowel Diseases (IBD where 5-HT may represent a key player in the pathogenesis of intestinal inflammation. The focus of this review is on mechanism(s involved in EC cell ‘mechanosensation’ and critical gaps in our knowledge for future research. Much of our knowledge and concepts are from a human BON cell model of EC, although more recent work has included other cell lines, native EC cells from mouse and human and intact mucosa. EC cells are ‘mechanosensors’ that respond to physical forces generated during peristaltic activity by translating the mechanical stimulus (MS into an intracellular biochemical response leading to 5-HT and ATP release. The emerging picture of mechanosensation includes Piezo 2 channels, caveolin-rich microdomains and tight regulation of 5-HT release by purines. The ‘purinergic hypothesis’ is that MS releases purines to act in an autocrine / paracrine manner to activate excitatory (P2Y1, P2Y4, P2Y6, A2A/A2B or inhibitory (P2Y12, A1, A3 receptors to regulate 5-HT release. MS activates a P2Y1/Gαq/PLC/IP3-IP3R/SERCA Ca2+signaling pathway, an A2A/A2B–Gs/AC/cAMP-PKA signaling pathway, an ATP-gated P2X3 channel, and an inhibitory P2Y12 -Gi/o/AC-cAMP pathway. In human IBD, P2X3 is down regulated and A2B is up regulated in EC cells, but the pathophysiological consequences of abnormal mechanosensory or purinergic 5-HT signaling remain unknown. EC cell mechanosensation remains poorly understood.

The separation of vibrational coherence from ground- and excited-electronic states in P3HT film

KAUST Repository

Song, Yin

2015-06-07

© 2015 AIP Publishing LLC. Concurrence of the vibrational coherence and ultrafast electron transfer has been observed in polymer/fullerene blends. However, it is difficult to experimentally investigate the role that the excited-state vibrational coherence plays during the electron transfer process since vibrational coherence from the ground- and excited-electronic states is usually temporally and spectrally overlapped. Here, we performed 2-dimensional electronic spectroscopy (2D ES) measurements on poly(3-hexylthiophene) (P3HT) films. By Fourier transforming the whole 2D ES datasets (S (λ 1, T∼ 2, λ 3)) along the population time (T∼ 2) axis, we develop and propose a protocol capable of separating vibrational coherence from the ground- and excited-electronic states in 3D rephasing and nonrephasing beating maps (S (λ 1, ν∼ 2, λ 3)). We found that the vibrational coherence from pure excited electronic states appears at positive frequency (+ ν∼ 2) in the rephasing beating map and at negative frequency (- ν∼ 2) in the nonrephasing beating map. Furthermore, we also found that vibrational coherence from excited electronic state had a long dephasing time of 244 fs. The long-lived excited-state vibrational coherence indicates that coherence may be involved in the electron transfer process. Our findings not only shed light on the mechanism of ultrafast electron transfer in organic photovoltaics but also are beneficial for the study of the coherence effect on photoexcited dynamics in other systems.

The separation of vibrational coherence from ground- and excited-electronic states in P3HT film

International Nuclear Information System (INIS)

Song, Yin; Hellmann, Christoph; Stingelin, Natalie; Scholes, Gregory D.

2015-01-01

Concurrence of the vibrational coherence and ultrafast electron transfer has been observed in polymer/fullerene blends. However, it is difficult to experimentally investigate the role that the excited-state vibrational coherence plays during the electron transfer process since vibrational coherence from the ground- and excited-electronic states is usually temporally and spectrally overlapped. Here, we performed 2-dimensional electronic spectroscopy (2D ES) measurements on poly(3-hexylthiophene) (P3HT) films. By Fourier transforming the whole 2D ES datasets (S(λ 1 ,T ~ 2 ,λ 3 )) along the population time (T ~ 2 ) axis, we develop and propose a protocol capable of separating vibrational coherence from the ground- and excited-electronic states in 3D rephasing and nonrephasing beating maps (S(λ 1 ,ν ~ 2 ,λ 3 )). We found that the vibrational coherence from pure excited electronic states appears at positive frequency (+ν ~ 2 ) in the rephasing beating map and at negative frequency (−ν ~ 2 ) in the nonrephasing beating map. Furthermore, we also found that vibrational coherence from excited electronic state had a long dephasing time of 244 fs. The long-lived excited-state vibrational coherence indicates that coherence may be involved in the electron transfer process. Our findings not only shed light on the mechanism of ultrafast electron transfer in organic photovoltaics but also are beneficial for the study of the coherence effect on photoexcited dynamics in other systems

h5-HT(1B) receptor-mediated constitutive Galphai3-protein activation in stably transfected Chinese hamster ovary cells: an antibody capture assay reveals protean efficacy of 5-HT.

Science.gov (United States)

Newman-Tancredi, Adrian; Cussac, Didier; Marini, Laetitia; Touzard, Manuelle; Millan, Mark J

2003-03-01

1. Serotonin 5-HT(1B) receptors couple to G-proteins of the Gi/o family. However, their activation of specific G-protein subtypes is poorly characterised. Using an innovative antibody capture/guanosine-5'-0-(3-[(35)S]thio)-triphosphate ([(35)S]GTPgammaS) binding strategy, we characterised Galpha(i3) subunit activation by h5-HT(1B) receptors stably expressed in Chinese hamster ovary (CHO) cells. 2. The agonists, 5-HT, alniditan and BMS181,101, stimulated Galpha(i3), whereas methiothepin and SB224,289 behaved as inverse agonists. The selective 5-HT(1B) receptor ligand, S18127, modestly stimulated Galpha(i3) and reversed the actions of both 5-HT and methiothepin. S18127 (1 micro M) also produced parallel, dextral shifts of the 5-HT and methiothepin isotherms. 3. Isotopic dilution experiments ([(35)S]GTPgammaS versus GTPgammaS) revealed high-affinity [(35)S]GTPgammaS binding to Galpha(i3) subunits in the absence of receptor ligands indicating constitutive activity. High-affinity [(35)S]GTPgammaS binding was increased 2.8-fold by 5-HT with an increase in the affinity of GTPgammaS for Galpha(i3) subunits. In contrast, methiothepin halved the number of high-affinity binding sites and decreased their affinity. 4. h5-HT(1B) receptor-mediated Galpha(i3) subunit activation was dependent on the concentration of NaCl. At 300 mM, 5-HT stimulated [(35)S]GTPgammaS binding, basal Galpha(i3) activation was low and methiothepin was inactive. In contrast, at 10 mM NaCl, basal activity was enhanced and the inverse agonist activity of methiothepin was accentuated. Under these conditions, 5-HT decreased Galpha(i3) activation. 5. In conclusion, at h5-HT(1B) receptors expressed in CHO cells: (i) inverse agonist induced inhibition of Galpha(i3), and its reversal by S18127, reveals constitutive activation of this Galpha subunit; (ii) constitutive Galpha(i3) activation can be quantified by isotopic dilution [(35)S]GTPgammaS binding and (iii) decreasing NaCl concentrations enhances Galpha(i3

Huperzine A Alleviates Oxidative Glutamate Toxicity in Hippocampal HT22 Cells via Activating BDNF/TrkB-Dependent PI3K/Akt/mTOR Signaling Pathway.

Science.gov (United States)

Mao, Xiao-Yuan; Zhou, Hong-Hao; Li, Xi; Liu, Zhao-Qian

2016-08-01

Oxidative glutamate toxicity is involved in diverse neurological disorders including epilepsy and ischemic stroke. Our present work aimed to assess protective effects of huperzine A (HupA) against oxidative glutamate toxicity in a mouse-derived hippocampal HT22 cells and explore its potential mechanisms. Cell survival and cell injury were analyzed by MTT method and LDH release assay, respectively. The production of ROS was measured by detection kits. Protein expressions of BDNF, phosphor-TrkB (p-TrkB), TrkB, phosphor-Akt (p-Akt), Akt, phosphor-mTOR (p-mTOR), mTOR, phosphor-p70s6 (p-p70s6) kinase, p70s6 kinase, Bcl-2, Bax, and β-actin were assayed via Western blot analysis. Enzyme-linked immunosorbent assay was employed to measure the contents of nerve growth factor, brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4). Our findings illustrated 10 μM HupA for 24 h significantly protected HT22 from cellular damage and suppressed the generation of ROS. Additionally, after treating with LY294002 or wortmannin [the selective inhibitors of phosphatidylinositol 3 kinase (PI3K)], HupA dramatically prevented the down-regulations of p-Akt, p-mTOR, and p-p70s6 kinase in HT22 cells under oxidative toxicity. Furthermore, it was observed that the protein levels of BDNF and p-TrkB were evidently enhanced after co-treatment with HupA and glutamate in HT22 cells. The elevations of p-Akt and p-mTOR were abrogated under toxic conditions after blockade of TrkB by TrkB IgG. Cellular apoptosis was significantly suppressed (decreased caspase-3 activity and enhanced Bcl-2 protein level) after HupA treatment. It was concluded that HupA attenuated oxidative glutamate toxicity in murine hippocampal HT22 cells via activating BDNF/TrkB-dependent PI3K/Akt/mTOR signaling pathway.

A Multi-Site Campaign to Measure Solar-Like Oscillations in Procyon. II. Mode Frequencies

DEFF Research Database (Denmark)

Bedding, Timothy R.; Kjeldsen, Hans; Campante, Tiago L.

2010-01-01

  We have analyzed data from a multi-site campaign to observe oscillations in the F5 star Procyon. The data consist of high-precision velocities that we obtained over more than three weeks with 11 telescopes. A new method for adjusting the data weights allows us to suppress the sidelobes in the p...

Optimalization activity of ZnO NR/TiO2 NR-P3HT as an active layer based on hybrid bulk heterojunction on dye sensitized solar cell (DSSC)

International Nuclear Information System (INIS)

Saputri, Liya Nikmatul Maula Zulfa; Ramelan, Ari Handono; Hanif, Qonita Awliya; Hasanah, Yesi Ihdina Fityatal; Prajanira, Lau Bekti; Wahyuningsih, Sayekti

2016-01-01

Dye sensitized solar cell (DSSC) with metal inorganic and conjugated organic polymer mixture, ZnO NR/TiO 2 NR-P3HT as an active layer based on hybrid bulk heterojunction has been studied. The hybrid material was used to optimize DSSC performs for better efficiency than only TiO 2 as an electrode. Synthesis of TiO 2 nanorods (NR) was conducted by ball milling 1000 rpm for 4 hours and strong base reaction by hydrothermal process at 120 °C overnight. And the ZnO NR was synthesized from Zn(NO 3 ) 2 .4H 2 O precusor by hydrotermal process at 90 °C for 5 hours and calcined on various temperature s of 400, 600, and 800 °C. ZnO NR was coated into an Tndium Tin Oxide (TTO) glass to collecting electron s effectively, where TiO 2 NR were incorporated with poly(3 -hexylthiophene) (P3HT) on various concentration s of 5, 10, 15 mg/mL to obtain a larger surface area. Material characterization were performed by X -Ray Diffraction (XRD) and Uv-Vis spectrophotometer. For an application of DSSC were measured by T-V Keithley Multimeter and the efficiency of DSSC at various P3HT’s concentrations of 5, 10, 15 mg/mL were 7.44 × 10 −3 , 0.0114, 0.0104, respectively. The maximum efficiency of DSSC was showed when TiO 2 NR-P3HT’s concentration was 10 mg/mL.